iPA/453/R-94/066/F
Office of Air Quality
Protection Planning and Standards
Research Triangle Park, NC 27711
STUDY OF
RGANIC COMPOUND EMISSIONS
FROM
AND COMMERCIAL PRODUCTS
ducts and Packaging Systetns
-------
REPORT TO CONGRESS
VOLATILE ORGANIC COMPOUND EMISSIONS
FROM
CONSUMER AND COMMERCIAL PRODUCTS
VOLUME 6
AEROSOL PRODUCTS AND PACKAGING SYSTEMS
Emission Standards Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
September 1994
-------
ACKNOWLEDGEMENT
The Report to Congress on VOC Emissions from Consumer and Commercial
Products was completed with a great degree of cooperation and assistance from the Chemical
Specialties Manufacturers Association, the Cosmetic, Toiletry, and Fragrance Association,
the Soap and Detergent Association, the Automotive Chemical Manufacturers Council, the
Adhesive and Sealant Council, and the National Aerosol Association.
The lead engineer for the consumer and commercial products study and report to
Congress was Bruce Moore of the Emission Standards Division, Office of Air Quality
Planning and Standards. Extensive clerical support was provided by Mary Hinson also of the
Emission Standards Division.
11
-------
TABLE OF CONTENTS
Section Page
1.0 INTRODUCTION 1-1
1.1 The Problem 1-1
1.1.1 Ozone Nonattainment and Small Sources of VOC Emissions .... 1-1
1.1.2 VOC's or NOX - Which Should We Control? 1-1
1.2 Congressional Response - The Clean Air Act of 1990 1-2
1.2.1 Requirements under §183(e) - Consumer and Commercial Products 1-2
1.2.2 Scope of Consumer and Commercial Products under §183(e) .... 1-3
1.2.3 The Report to Congress ~ Purpose and Structure . 1-3
1.3 Introduction to Aerosol Products and Packaging Systems 1-5
1.3.1 Definition of Aerosol Product 1-5
1.3.2 Aerosol Products as Sources of VOC Emissions 1-6
1.4 References 1-7
2.0 AEROSOL SYSTEM COMPONENTS 2-1
2.1 Introduction 2-1
2.2 Formulation 2-1
2.3 Propellants 2-4
2.3.1 Hydrocarbon Aerosol Propellants 2-7
2.3.2 Non-VOC Compressed Gases 2-12
2.3.3 Fluorocarbons 2-14
2.3.4 Propellant Blends 2-15
2.3.5 Summary of Propellant Selection Considerations 2-19
2.4 Aerosol Valve Assembly 2-19
2.4.1 Vertical Action Valves 2-20
2.4.2 Tilt Valves 2-25
2.4.3 Female Valves 2-28
2.4.4 Total Release Valve Systems 2-28
iii
-------
TABLE OF CONTENTS
(CONTINUED)
Section Page
2.4.5 Summary of Valve Selection Considerations 2-28
2.5 Aerosol Containers 2-29
2.5.1 Regulatory Concerns 2-29
2.5.2 Metal Can Construction 2-31
2.5.3 Glass Container Construction 2-36
2.5.4 Plastic Container Construction 2-38
2.6 References 2-40
3.0 CHARACTERIZATION OF THE AEROSOL INDUSTRY 3-1
3.1 Industry History and Development 3-1
3.2 Structure of the Industry 3-2
3.2.1 Marketers 3-3
3.2.2 Fillers 3-4
3.2.3 Formulators 3-9
3.2.4 Propellant Suppliers 3-9
3.2.5 Raw Material Vendors 3-10
3.2.6 Container Manufacturers 3-13
3.2.7 Valve Suppliers 3-16
3.2.8 Cover Cap Manufacturers 3-18
3.3 References 3-18
4.0 ALTERNATIVE DISPENSING TECHNOLOGIES 4-1
4.1 Introduction 4-1
4.2 The "Bag-in-Can" System 4-1
4.3 Piston Cans 4-5
4.4 The Enviro-Spray® System 4-7
4.5 Pump Sprays 4-9
iv
-------
TABLE OF CONTENTS
(CONTINUED)
Section Page
4.6 Dispensing Closures (Squeeze Bottles) 4-12
4.7 Twist-N-Mist It* 4-14
4.8 The Exxel® System 4-16
4.9 The Mistlon Eco-Logical® System 4-17
4.10 The Airspraf System 4-18
4.11 The Selvac® System 4-18
4.12 The Werding Nature Spraf System 4-19
4.13 Vaporizers 4-19
4.14 Stick and Roll-on Applicators 4-19
4.15 Additional Considerations of Delivery System Selection 4-20
4.16 References 4-24
5.0 CHARACTERISTICS OF SELECTED AEROSOL PRODUCTS 5-1
5.1 Introduction 5-1
5.2 Personal Care Products 5-1
5.2.1 Hair Sprays 5-1
5.2.2 Shaving Creams 5-2
5.2.3 Underarm Antiperspirants 5-2
5.2.4 Underarm Deodorants 5-3
5.2.5 Medicinal Products 5-3
5.2.6 Hair Lusterizers 5-3
5.2.7 Hair Mousse 5-4
5.2.8 Colognes and Perfumes 5-4
5.2.9 Other Personal Products 5-4
V
-------
TABLE OF CONTENTS
(CONTINUED)
Section Page
5.3 Household Products 5-5
5.3.1 Room Deodorants and Disinfectants 5-5
5.3.2 Window Cleaners 5-6
5.3.3 Oven Cleaners 5-6
5.3.4 Hard Surface Cleaners 5-7
5.3.5 Carpet and Rug Cleaners 5-8
5.3.6 Spray Starch Laundry Products 5-8
5.3.7 Fabric Finish Laundry Products 5-9
5.3.8 Pre-wash Laundry Products 5-9
5.3.9 Furniture Waxes and Polishes 5-10
5.3.10 Furniture Cleaners 5-10
5.3.11 Other Household Products 5-10
5.4 Automotive/Industrial Products 5-11
5.4.1 Lubricants and Silicones 5-11
5.4.2 Carburetor and Choke Cleaners 5-12
5.4.3 Engine Starting Fluids 5-12
5.4.4 Tire Inflators and Sealants 5-13
5.4.5 Cleaners 5-13
5.4.6 Brake Cleaners 5-14
5.4.7 Engine Degreasers 5-14
5.4.8 Spray Undercoating 5-15
5.4.9 Windshield and Lock Deicer 5-15
5.4.10 Other Automotive/Industrial Products 5-15
5.5 Paints, Primers, and Varnishes 5-16
5.6 Insect Sprays 5-16
5.6.1 Space Insecticides 5-17
5.6.2 Residual Insecticides 5-18
5.6.3 Insect Repellents 5-19
5.7 Food Products 5-19
5.8 Animal Products 5-20
VI
-------
TABLE OF CONTENTS
(CONTINUED)
5.9 Miscellaneous Products 5-20
5.10 References 5-20
6.0 CONCLUSIONS 6-1
vii
-------
LIST OF FIGURES
Figure
2-1 Typical Critical Path for Development of an Aerosol Insecticide 2-5
2-2 Components of the Precision Vertical Valve 2-21
2-3 Operation of the Precision Vertical Valve 2-22
2-4 Cross Section of Typical Flat Cup and Conical Cup Valves 2-24
2-5 Cross Section of a Typical Tilt Valve 2-26
2-6 Typical Female Valve 2-27
2-7 Cross Section of a Typical "Snap-lock" Dome Top 2-32
4-1 The Sepro Can9 4-2
4-2 American National Can Company's Mira-Flo® Piston Can 4-6
4-3 Various Stages in the Operation of an Enviro-Spray^ Product 4-8
4-4 Dispensing Closures Made by Seaquist Closures Division 4-13
4-5 Tmst-N-Mist II® by CIDCO Group, Inc. 4-15
Vlll
-------
LIST OF TABLES
Table Page
1-1 U. S. Aerosol Products Filled in 1989 1-4
1-2 Total VOC Content of U. S. Aerosol Products in 1989 1-6
2-1 Physical Properties of Hydrocarbon Propellants 2-8
2-2 Typical Hydrocarbon Propellant Pressures and Market Shares 2-11
2-3 Physical Properties of Fluorocarbons 2-16
2-4 DOT Requirements for Metal Aerosol Containers 2-30
2-5 Can Sizes Marketed by U. S. Can Company 2-35
3-1 U. S. Aerosol Product Fillers 3-5
3-2 U. S. Aerosol Propellant Suppliers 3-11
3-3 Raw Materials Used in Aerosol Formulations 3-12
3-4 U. S. Aerosol Container Manufacturers 3-14
3-5 U. S. Aerosol Valve Manufacturers 3-17
3-6 Aerosol Container Cover Cap Manufacturers 3-19
4-1 Bag-in-Can Dispenser Systems 4-4
4-2 Pump Sprayer Systems and Suppliers 4-10
4-3 Materials Used in Alternative Dispensing Systems 4-21
4-4 Alternative Dispensing Systems and Their Applications 4-23
IX
-------
1.0 INTRODUCTION
1.1 THE PROBLEM
1.1.1 Ozone Nonattainment and Small Sources of VQC Emissions
National air quality monitoring data from 1986 through 1988 indicate that
there are approximately 100 geographic areas which failed to attain the national ambient air
quality standards (NAAQS) for ozone. Ozone is a major component of smog which poses
major health and environmental concerns when present hi high concentrations at ground
level. It is a photochemical oxidant which is formed in the atmosphere through a series of
complex chemical reactions between precursor emissions of volatile organic compounds
(VOC's) and oxides of nitrogen (NOx) in the presence of sunlight.
While most of the large, stationary sources of VOC emissions are covered by
existing regulations, an examination of emissions data completed in 1989 by the Office of
Technology Assessment (OTA) indicates that individually small, dispersed sources of VOC's
(area sources) contribute significantly to the continuing ozone nonattainment problem.
According to the OTA report, Catching Our Breath - Next Steps for Reducing Urban
Ozone , one area source of VOC emissions is the use of a wide range of consumer and
commercial products.
1.1.2 VOC's or NOx - Which Should We Control?
Ground-level (tropospheric) ozone is formed through a series of complex
chemical reactions involving VOC's and NOx in the presence of sunlight. Reductions in the
amount of ozone formed can be obtained through reducing the concentrations of VOC and/or
NOx available for reaction. A recent report, Rethinking the Ozone Problem in Urban and
Regional Air Pollution , published by the National Academy of Science explains that a key
factor in reducing ozone formation is the ratio of VOC to NOx in the ambient air. When the
VOC to NOx ratio is greater than 10:1, VOC reductions have little effect because of the
1-1
-------
excess concentration of VOC's available for reaction. In such "NOx-limited" scenarios,
NOx controls may be much more effective than VOC controls alone in reducing ozone
formation. Conversely, in airsheds which are not NOx-limited, VOC controls can be
effective in reducing ozone formation.
Although VOC controls alone may offer little reduction in ozone formation
under some conditions, there are many instances in which the VOC to NOx ratio favors
VOC controls. The U.S. Environmental Protection Agency (EPA) does not anticipate
abandonment of efforts to reduce ozone formation through reduction in VOC emissions,
especially in the case of area sources such as consumer and commercial products. However,
this new way of thinking could affect future strategies for stationary and mobile sources for
which NOx and VOC controls could be tailored to specific conditions.
1.2 CONGRESSIONAL RESPONSE: THE CLEAN AIR ACT OF 1990
1.2.1 Requirements Under §183(6) — Consumer and Commercial Products
Although control of one small source of VOC emissions may contribute little
to overall ambient air quality, VOC reductions obtained through regulation of multiple small
sources could have a beneficial additive effect. Section 183(e) of the Clean Air Act (CAA)
as amended in 1990 requires the EPA to conduct a study of emissions of VOC's into the
ambient air from consumer and commercial products. The objectives of the study are (1) to
determine the potential of consumer and commercial product VOC emissions to contribute to
ozone levels which violate the NAAQS for ozone; and (2) to establish criteria for regulating
consumer and commercial products or classes or categories of products under the authority of
§183(e) of the CAA. In establishing criteria for regulating consumer and commercial
products, the EPA must take into consideration (1) the uses, benefits, and commercial
demand of consumer and commercial products; (2) any health or safety functions served by
the products; (3) those consumer and commercial products that emit highly reactive VOC's
into the ambient air; (4) those products that are subject to the most cost-effective controls;
and (5) the availability of any alternatives to such consumer and commercial products that are
of comparable costs, considering health, safety, and environmental impacts. On completion
1-2
-------
of the study, the EPA must submit a report to Congress that documents the results of the
study.
Upon completion of the report, the EPA must list those categories of products
which are determined, based on the study, to account for at least 80 percent of the total VOC
emissions, on a reactivity-adjusted basis, from consumer and commercial products in areas
which violate the NAAQS for ozone. The EPA must divide the list into 4 groups by
priority. Pursuant to this requirement, the EPA will publish the prioritized category list in
the Federal Register following submittal of the report to Congress. Beginning no later than 2
years following publication of the list, the EPA must regulate one group every two years
until all 4 groups are regulated.
1.2.2 Scope of Consumer and Commercial Products under §183(e)
According to the definition in §183(e), "the term 'consumer or commercial
product' means any substance, product (including paints, coatings, and solvents), or article
(including any container or packaging) held by any person, the use, consumption, storage,
disposal, destruction, or decomposition of which may result in the release of volatile organic
compounds. The term does not include fuels or fuel additives regulated under section 211,
or motor vehicles, non-road vehicles, and non-road engines as defined under section 216."
The EPA has determined that the statutory definition of consumer or
commercial product is much broader than just the "traditional" consumer products (e.g.,
personal care products, household cleaning products, household pesticides, etc.). Instead,
consumer and commercial products include virtually all VOC-emitting products used in the
home, by businesses, by institutions, and in industrial manufacturing operations. Among
these products are a wide range of surface coatings, metal cleaning solvents, graphic arts
inks, industrial adhesives, agricultural pesticides, asphalt paving materials, and many other
products used in industrial manufacturing processes, many of which have been previously
regulated by the EPA and/or by the States.
1-3
-------
1.2.3 The Report to Congress — Purpose and Structure
The primary purpose of the study and report to Congress is to educate the
EPA and Congress on consumer and commercial products as contributors to ozone
nonattainment and to identify opportunities for reduction of VOC emissions from the use of
these products. In addition, some information obtained from the EPA studies was used to
establish criteria for regulation of consumer and commercial products and utilized during the
process of exercising the criteria to develop the regulatory agenda.
In order to prepare the report, the EPA conducted several individual studies.
Some of these studies pertain to specific categories of products for which the EPA has little
or no existing information; other "generic" studies focus on topics which do not relate to any
particular category of products.
Generic Studies
Inventory of VOC Emissions from Consumer and Commercial Products
Fate of Consumer and Commercial Product VOC's in Wastewater
Fate of Consumer and Commercial Product VOC's in Landfills
Aerosol Products and Packaging Systems
Economic Incentive Regulatory Strategies
Product Category Studies
Underarm Antiperspirants and Deodorants
Hair Care Products
Aerosol Spray Paints
Adhesives and Sealants
Household Cleaners
Nonagricultural Pesticides (including Antimicrobials)
Automotive Ajtermarket Products
Room Deodorants
Architectural and Industrial Maintenance Coatings
1-4
-------
The core elements of each product category report are (1) a product category
description, which includes the scope of products in the category, typical formulations, key
terminology, and other characteristics of the category; (2) an industry profile which discusses
the history and development of the industry and the types, number, and functions of
companies which comprise the industry; (3) a discussion of possible control measures or
opportunities for reduction of VOC emissions from the category, including reformulation,
substitution, labeling, directions for use, etc.; and (4) a limited analysis of impacts of
possible control measures, including emission reductions, effects on product efficacy, etc.
There generally is no information presented on cost-effectiveness of control measures.
1.3 AEROSOL PRODUCTS AND PACKAGING SYSTEMS
1.3.1 Definition of Aerosol Product
The term "aerosol product" is defined by the Chemical Specialties
Manufacturers Association (CSMA) as "a sealed container pressurized with liquified or
compressed gases so that the product is self-dispensing." The Department of Transportation
(DOT) defines an aerosol as "a sealed package containing base product ingredients, in which
one or more propellants are dissolved or dispersed, and fitted with a dispensing valve."
According to these definitions, products such as trigger sprays or pump action dispensers are
not considered aerosol products.
The concept of the aerosol product as a system is emphasized throughout this
report. The term "system" has been defined as "a group of interrelated, interacting, or
interdependent constituents forming a complex whole. There are 4 primary components
that comprise the aerosol system: the product, the propellant, the valve, and the container.
The product and propellant collectively are referred to as the formulation. Ideally, the
system is designed such that each component operates in conceit with the others.
Consequently, as in any system of interrelated components, modification of one or more
system components must be carried out judiciously in order to preserve the functionality of
the system. The individual components of the aerosol packaging system and their interactions
are discussed in detail in Section 2.0, Aerosol System Components.
1-5
-------
1.3.2 Aerosol Consumer Products as Sources of VOC Emissions
In today's aerosol industry, nearly all aerosol consumer products employ
hydrocarbon (HC) propellants. These propellants (primarily propane, normal butane, and
isobutane) are VOC's. The HC propellants were substituted for chlorofluorocarbons (CFC's)
which were determined to contribute to the depletion of stratospheric ozone. The conversion
to HC propellants was initiated by the industry in 1975 and was virtually complete by 1978,
when the EPA banned the use of CFC's in most aerosol products. A discussion of this shift
in propellants and its effect on the aerosol industry is presented in Section 3.1, Industry
History and Development.
The CSMA publishes an annual Aerosol Pressurized Products Survey that
reports information on aerosol containers filled in the United States. The 1989 CSMA
n
survey reports that approximately 2.9 billion units were filled in the United States in 1989.
Table 1-1 presents data from the 1989 survey for several categories and subcategories of
products. As the table shows, personal care products comprise the largest category followed
by household products, automotive/industrial products, paints and finishes, insect sprays, and
others, respectively. Hair sprays alone account for almost 18 percent of the number of all
aerosol products filled in the United States. The next highest volume category includes
paints, primers, and varnishes.
The total amount of VOC's contained in aerosol products in 1989 was
estimated to be about 650,000 tons.4'^ Table 1-2 presents the various categories of aerosol
products and the estimated total amount of VOC's contained in each category.
1-6
-------
1.4 REFERENCES
1. U.S. Congress, Office of Technology Assessment, Catching our Breath: Next Steps
for Reducing Urban Ozone, OTA-O-412, Government Printing Office, Washington,
D.C., July 1989.
2. National Research Council, Committee on Tropospheric Ozone Formation and
Measurement, Rethinking the Ozone Problem, in Urban and Regional Air Pollution,
Washington, D.C., 1991.
3. Webster's II — New Riverside University Dictionary. Riverside Publishing
Company, 1984.
4. Chemical Specialties Manufacturers Association, Aerosol Pressurized Products
Survey - United States 1989, published 1990.
5. Radian Corporation. Control Technology Overview Report: Volatile Organic
and Chlorofluorocarbon Use in Aerosol Products. U. S. Environmental
Protection Agency, Air and Energy Engineering Research Laboratory. July
1990.
1-7
-------
TABLE 1-1
U. S. AEROSOL PRODUCTS FILLED IN 1989 4
Major Category
Personal Care
Products
Household Products
Automotive/
Industrial
Paints and Finishes
Insect Sprays
Food Products
Animal Products
Miscellaneous
TOTAL
Subcategory
Hair Sprays
Shaving Creams
Antiperspirants/Deodorants
Medicinals/Pharmaceuticals
Other Hair Products
Other Personal Products
Colognes/Perfumes
Subtotal
Room Deodorants/Disinfectants
Cleaners
Laundry Products
Waxes/Polishes
Other Household Products
Subtotal
Lubricants
Refrigerants
Carburetor/Choke Cleaner
Engine Starting Fluid
Tire Inflator/Sealant
Cleaners
Brake Cleaner
Engine Degreaser
Other Automotive/Industrial
Spray Undercoating
Windshield/Lock De-icer
Subtotal
Paints, Primers, Varnishes
Other Related Products
Subtotal
Space Insecticides
Residual Insecticides and Repellants
Subtotal
All Types
Veterinarian and Pet Products
Other Products
Units Filled
Number
516,193,000
232,476,000
221,751,000
30,845,000
9,356,000
3,050,000
1,338,000
1,013,660,000
220,660,000
173,838,000
144,850,000
94,951,000
45,800,000
680,000,000
114,932,000
101,141,000
49,603,000
42,726,000
35,728,000
33,292,000
31,008,000
27,665,000
23,622,000
9,446,000
5,828,000
475,000,000
331,436,000
18,564,000
350,000,000
124,538,000
72,462,000
197,000,000
175,000,000
8,000,000
12,000,000
2,910,660,000
Category
(%)
50.9
22.9
21.8
3.0
0.9
0.3
0.1
100.0
32.5
25.6
21.3
13.9
6.7
100.0
24.2
21.3
10.4
9.0
7.5
7.0
6.5
5.8
5.0
2.0
1.2
100.0
94.7
53
100.0
63.2
36.8
100.0
100.0
100.0
100.0
Total
(%)
17.7
8.0
7.6
1.1
0.3
0.1
0.0
34.9
7.6
6.0
5.0
3.3
1.6
23.4
3.9
3.5
1.7
1.5
1.2
1.1
1.1
1.0
0.8
0.3
0.2
16.3
11.4
0.6
12.0
4.3
2.5
6.8
6.0
0.3
0.4
100.0
1-8
-------
TABLE 1-2
TOTAL VOC CONTENT OF U. S. AEROSOL PRODUCTS IN 19892'3
Major Category
Personal Care
Products
Household
Products
Automotive/
Industrial
Paints and Finishes
Insect Sprays
Food Products
Animal Products
Miscellaneous
TOTAL
Subcategory
Hair Sprays
Shaving Creams
Antiperspirants/Deodorants
Medicinals/Pharmaceuticals
Other Hair Products
Other Personal Products
Colognes/Perfumes
Subtotal
Room Deodorants/Disinfectants
Cleaners
Laundry Products
Waxes/Polishes
Other Household Products
Subtotal
Lubricants
Refrigerants
Carburetor/Choke Cleaner
Engine Starting Fluid
Tire Inflator/Sealant
Cleaners
Brake Cleaner
Engine Degreaser
Other Automotive/Industrial
Spray Undercoating
Windshield/Lock De-icer
Subtotal
Paints, Primers, Varnishes
Other Related Products
Subtotal
Space Insecticides
Residual Insecticides and Repellants
Subtotal
All Types
Veterinarian and Pet Products
All Other Products
Volatile Organic Compounds
Amount Used
(Tons)
131,085
12,070
21,265
845
12,635
425
950
179,275
40,095
9,125
31,640
22,870
7.050
110,780
47,895
0
18,600
10,870
12,280
2,135
17,540
11,740
5,835
1,770
2,110
130,775
117,890
6,605
124,495
34,290
28,300
62,590
42,415
1,755
2,350
654,435
Category
(%)
73.1
6.7
11.9
0.5
7.0
0.2
0.6
100.0
36.2
8.2
28.6
20.6
6.4
100.0
36.6
0.0
14.2
8.3
9.4
1.6
13.4
9.0
4.5
1.4
1.6
100.0
94.7
5.3
100.0
54.8
45.2
100.0
100.0
100.0
100.0
Total
(%)
20.1
1.9
3.2
0.1
1.9
0.0
0.1
27.3
6.2
1.4
4.8
3.5
1.1
17.0
7.4
0.0
2.8
1.7
1.9
0.3
2.7
1.8
0.9
0.2
0.3
20.0
18.1
1.1
19.2
5.2
4.3
9.5
6.5
0.2
0.3
100.0
1-9
-------
-------
SECTION 2.0
AEROSOL SYSTEM COMPONENTS
2.1 INTRODUCTION
The purpose of this section is to describe the components of the aerosol system, to
discuss the issues that are considered critical when designing a product, and to explain
how these issues can affect VOC emissions. There are 4 primary components that
comprise the aerosol system: the product, the propellant, the valve, and the container.
Each of these components must be designed so that the product will meet the needs of the
consumer. The formulation (product and propellant) is the most important part in that it
must perform as designed, while being chemically compatible with the can and valve
materials. The propellant must provide enough pressure so that the entire contents of the
can will be expelled, yet not so much pressure that the product becomes dangerous or the
spray pattern deteriorates. The valve design must achieve the desired spray pattern and
delivery rate. The container must be designed for safety, cost effectiveness, and
attractiveness.
2.2 FORMULATION
Almost all products that are available as aerosols are also available in other
packaging forms such as creams, gels, or liquids. A product is packaged as an aerosol
because of benefits to the consumer. To benefit the consumer, the product must be
efficacious, i.e., it must perform the function for which it is designed. The product
should be convenient, safe, and aesthetically pleasing (i.e., it should have little or no
offensive odor, not be messy, and be attractively packaged). The success of the marketed
product depends on how well the system meets each of these criteria.
An aerosol formulation is made up of 3 major components: the active ingredients,
the solvent, and the propellant. The active ingredients are the materials essential for the
2-1
-------
specific application for which the aerosol was designed. For example, the active
ingredient in a paint is the suspended solids, and the active ingredient in an insecticide is
the toxin. Solvents are usually present to act as diluents or to bring the active ingredients
into solution with the propellant. Typical solvents include ethanol, odorless mineral
spirits, and in some cases, water. The propellant is the third part of an aerosol and is
discussed in more detail in Section 2.3, Propellants.
The active ingredients are designed for a specific purpose such as odorizing
(perfumes or deodorizers) or killing insects (insecticides). The chemicals that make up
the active ingredients are almost as diverse as the number of products that are available.
Because of this diversity, it is difficult to make generalizations about formulations. Any
detailed discussion on formulations must take into consideration specific applications.
Therefore, more information on formulations for specific applications is included in
Section 5.0, Characteristics of Selected Aerosol Products.
While solvents perform a number of functions in aerosol products, their primary
purpose is to mix the active ingredients with the propellant. Solvents are also added to
control the particle size of the spray. For example, if the formulation consists of
chemicals that rapidly evaporate after discharge, a solvent may be added to retard the rate
of evaporation, resulting in a larger droplet size. In some cases, solvents are also added
to reduce the vapor pressure of the propellant system so that the aerosol product will
comply with Department of Transportation (DOT) regulations.
To successfully market a product, the manufacturer (marketer) must, go through a
series of steps. First, the product must be developed. The active ingredients, inactive
ingredients, and the propellant system must be selected. The next step is to determine if
the formulation is compatible with the packaging system and if it is chemically stable. It
is important to ensure that the formulation will not corrode the can or dissolve the valve.
It is equally important that the formulation remain stable throughout the lifetime of the
product. Next, the marketer must test the product to ensure that it is safe. This entails
flammability testing and lexicological studies. Once it is determined that the product is
2-2
-------
safe, the product must be tested for performance in the field to ensure that the product
performs as expected in the hands of the consumer. The next step is consumer testing, in
order to determine whether the product is likely to be accepted by the consumer. The
marketer is then ready to initiate the purchase of equipment or the negotiation of
contracts to produce the product, etc.
Concurrently with the last 3 phases, the marketer usually obtains the necessary
governmental approval. For example, insecticides, insect repellents, disinfectants,
disinfectant cleaners, fungicidal sprays, and herbicides are regulated by the EPA under
the Federal Insecticide and Fungicide and Rodenticide Act (FIFRA). The regulations
require all products subject to the Act to be registered with the FJ>A before interstate
shipment can occur. The regulations also contain labeling requirements for the products
that are affected.
The Food and Drug Administration (FDA) regulates foods, drugs, cosmetics, and
medical devices. The FDA must approve all ingredients in food products. Food
additives, including propellants, must be on the FDA's "Generally Recognized as Safe"
list. The FDA must also approve all drugs. An extensive new drug approval (NDA)
process is required of each new pharmaceutical product. Although non-prescription, or
"over-the-counter" (OTC), drugs do not require such pre-market approval, they must
meet the criteria of an existing drug monograph. Any drug product that deviates from an
existing drug monograph is subject to the more extensive NDA process. Personal care
products that affect bodily functions (e.g., antiperspirants, sunscreens, eye drops, etc.)
are regulated by the FDA as drugs. Although the FDA does not require pre-market
approval of cosmetics, it has authority to regulate cosmetic products. It can ban or
restrict ingredients for safety reasons, mandate warning labels, inspect manufacturing
facilities, issue regulatory letters, seize illegal products, and engage in nationwide
recalls.
In general, it takes 2 to 5 years to get an aerosol product to the market. This time
frame depends on the degree of product development, the extent of the required testing,
2-3
-------
regulatory requirements, and production needs. Figure 2-1 shows the critical path for the
development, approval, and marketing of an aerosol insecticide. In this case, the Federal
registration would take approximately 5 years.
2.3 PROPELLANTS
An aerosol propellant is defined as "a fluid capable of exerting a pressure when
T
held in a sealed container at room temperature."'' There are 3 major classes of
propellants: fluorocarbons, hydrocarbons (HC's), and compressed gases. The
fluorocarbons can be further divided into chlorofluorocarbons (CFC's),
hydrochlorofluorocarbons (HCFC's), and hydrofluorocarbons (HFC's). The VOC's
include HC's (propane, normal butane, and isobutane) and dimethyl ether. The non-VOC
compressed gases that are typically used as aerosol propellants are carbon dioxide (CC>2),
nitrous oxide (N2O), nitrogen (N2), and compressed air.
The first significant aerosol product was an insecticide produced in 1943 for use by
U. S. combat troops. This product and subsequent aerosol products used CFC's as
propellants primarily because they are nontoxic and nonflammable. The HC propellants
did not enter the market until about 1954. Studies conducted in the 1970's implicated the
CFC propellants as contributing to the depletion of stratospheric ozone. Therefore, in
1975, the aerosol industry began substituting HC's and compressed gases in those aerosol
products being manufactured that used CFC's. In 1975, approximately 50 percent of all
aerosols were filled with HC propellants. This conversion was costly to the aerosol
industry because many existing plants were not designed to handle flammable propellants.
By 1978, when CFC's were banned by the FJPA for use in most aerosol products, the
o
conversion from CFC's to HC's was virtually complete.
A propellant functions by exerting pressure inside the container and forcing the
product through the dip tube and into the rest of the valve assembly. When the valve is
opened, the product is forced out of the container by this pressure. Liquified gas
propellants (e.g., fluorocarbons or HC's) are used because they will maintain a relatively
2-4
-------
faS
§
7
B
G
CO
4
^"w I
s
a
£
•c
u
a.
£
SI
^
§
-------
constant pressure as the contents of the can are expended. A constant pressure is main-
tained because the liquid propellant is constantly vaporizing into the head space of the
container. As the liquid level of the container drops, more liquid-phase propellant
vaporizes until equilibrium is established. The liquid serves as a reservoir to maintain the
total pressure as the product level drops. This mechanism is contrasted with the
compressed gases that lose pressure as the head space inside the container increases.
Consequently, when a compressed gas is used, the container must be initially "over-
charged" so that there will be sufficient pressure to expel the entire contents.
The physical properties that affect how a propellant functions in a specific
application are the propellant's vapor pressure, solubility, and viscosity. The vapor
pressure determines how much pressure is exerted on the liquid inside the container
which, in turn, will affect the spray characteristics of the product. The solubility affects
the manner in which the product must be used by the consumer. If the propellant is not
soluble in the formulation, it is a two-phase formulation, and the container must be
shaken in order to mix the propellant and product. If the propellant is soluble in the
product, then it is a single-phase formulation, and no agitation is necessary. This is
important because some products, such as wall dispenser air fresheners, cannot be
shaken. Therefore, they must be single-phase formulations. The solvent properties of
the propellant in relation to the valve components, such as gaskets and dip tubes, can also
be important. If the propellant dissolves the valve components, the container may leak or
the valve may not function correctly. Furthermore, the propellants must be pure.
Impurities can result in problems such as inoperable valves or container corrosion. The
propellant must be chemically stable in the formulation so that the propellant and product
or solvent do not react to form undesirable compounds. The spray characteristics are
affected by the viscosity. A high viscosity formulation may be discharged as a stream
and not a spray. The propellant also influences whether the product is discharged as a
foam, stream, or spray.
In addition to the propellant's physical properties, the formulator must consider its
flammability, toxicity, odor, and cost. If the propellant is flammable, precautions must
2-6
-------
be taken during storage and the filling process to minimize the possibility of explosion.
If the propellant is toxic, specific procedures must be implemented to protect employees,
and the propellant is unsuitable for some applications such as food or personal care
products. If the propellant has an undesirable odor, the consumer is less likely to use the
product. If the propellant is very expensive, the cost of the product may affect consumer
acceptance. When selecting a propellant for a product, the marketer must be aware of
the ramifications of each of these issues.
The following sections discuss the characteristics of the 3 major classes of
propellants and their respective advantages and disadvantages. For each specific
application, these characteristics must be considered before a decision can be made to use
a specific propellant.
2.3.1 Hydrocarbon Aerosol Propellants
Propane, n-butane, and isobutane are the principal VOC propellants used in today1 s
aerosols. An additional VOC propellant, dimethyl ether (DME), is gaining more
acceptance in the aerosol consumer product market. Table 2-1 presents some of the
physical properties of these VOC propellants.
The HC propellants are used because they have several very attractive properties.
They are nontoxic, noncarcinogenic, noncorrosive, abundant, and cost effective (currently
$.19 per pound, plus freight). These liquified gas propellants provide a consistent
pressure over the life of the product, and they can be blended to achieve a wide range of
vapor pressures. They are easy to transport, store, and handle. The major disadvantages
are that they are flammable and that they are photochemically reactive in the atmosphere
(i.e, they contribute to the formation of tropospheric ozone).
Isobutane is the most prevalent of the HC propellants. It has a vapor pressure
between that of n-butane and propane. A disadvantage is that it is the most
2-7
-------
TABLE 2-1
PHYSICAL PROPERTIES OF HC PROPELLANTS4
Property
Formula
Molecular
Weight
Vapor Pressure
(psig at 70°F)
Freezing Point
(°F at 1 atm)
Boiling Point
(°F at 1 atm)
Propane Isobutane
c3Hg £4^10
44.1 58.1
108 31.1
-305.9 -255.3
-43.7 10.9
n-Butane
C4Hio
48.1
16.9
-216.9
31.1
Dimethyl Ether
CH3-O-CH3
46.1
63.0
-217.3
-12.7
Solubility in
Water 0.000
(wt % at 70°F)
Flammability in
Air 2.2 - 9.5
(Vol %)
Ozone Depletion 0
Potential
Greenhouse Potential
(relative to 0
CFC-12 at 1.0)
Photochemical
Reactivity* 0.23
(g 03/g VOC)
0.008
0.008
1.8-8.4 1.9-8.5
0
0.57
0.42
34.17
3.4- 18
Insignificant
Pending
As of December 1991, the EPA had not determined that a suitable relative reactivity scale was
available.
2-8
-------
photochemically reactive of the HC propellants. Isobutane is typically used in products
such as antiperspirants, window cleaners, starches, and hair sprays.
Propane is used whenever a propellant is needed with a pressure greater than that
of isobutane (31 psig at 70°F). With a vapor pressure of 108 psig at 70°F, it provides
the highest pressure of the HC propellants. At 130°F, propane has a vapor pressure of
about 255 psig and, when used alone as a pure propellant, does not satisfy the DOT
requirements for normal can pressure. Therefore, it is usually employed in a blend
rather than as the sole propellant. Propellant blends are further discussed below.
Products that generally use propane as a propellant include heavy oils, greases, and
undercoatings, because these products are very viscous and require higher pressures for
product delivery.
The third HC propellant, n-butane, is rarely used alone because it has such a low
vapor pressure (17 psig at 70°F). It is used primarily in a blend with propane so that the
resulting propellant will have an acceptable vapor pressure.
Other HC's that have been used as propellants include ethane, n-pentane, and
isopentane. The pentanes are not usually employed as propellants because they develop
no positive gauge pressure at room temperatures. Their normal boiling points range from
82 to 97°F. Ethane, on the other hand, is a gaseous vapor under typical aerosol
temperatures and pressures. It could be more correctly classified as a compressed gas.
Because of ethane's very high pressure (543 psig at 70°F), it has no significant use in the
a
aerosol industry.
Although not a true hydrocarbon, dimethyl ether (DME) is also used as a HC
propellant. Its major advantage is that it is soluble in water (see Table 2-1).
Accordingly, it is the only liquified gas propellant that can be combined with a product
containing a significant amount of water to yield a single-phase formulation. By using
DME, formulators may be able to reformulate some products to reduce their total VOC
content. Its major disadvantage is that it is more expensive ($0.38 per pound, plus
2-9
-------
freight) than the true HC propellants. Examples of products that can be propelled by
DME are colognes, hair sprays, room deodorizers, insecticides, and waterborne coatings.
Blends of HC and DME can be used for hair sprays, household cleaners, and adhesives.
To achieve desirable spray characteristics, the formulator may require a propellant
that has a pressure different from the vapor pressures of any of the pure compounds.
This can be achieved by blending two propellants. The most common mixture is a
propane/isobutane blend. For example, a mixture of 41.9 percent (by weight) propane
and 58.1 percent isobutane results in a propellant with a pressure of 70 psig at 70°F. A
significant problem associated with a HC blend is that the more volatile component of the
mixture vaporizes into the headspace more quickly than the lower volatility component.
As the product is expelled (and the higher volatility component is expended more rapidly
than the lower volatility component), the lower volatility component accounts for an
increasing percentage of the liquid propellant mixture. Consequently, the total pressure
of the mixture decreases with product usage. This problem is exacerbated with the use of
vapor tap valves because the higher volatility component is lost not only to the headspace
but through the valve as well.
To be able to distinguish among the different mixtures, the industry has
established a convention for identifying HC propellants and blends. The name begins
with an "A" (indicating aerosol grade) and is followed by a number which indicates the
pressure of the propellant in psig at 70°F. For example, A-70 is a mixture of
41.9 percent propane and 58.1 percent isobutane and has a total pressure of 70 psig at
70°F. Although Phillips Petroleum Company copyrighted the "A" designations for
blends during the 1950's, today this terminology is used genetically by the industry. The
o
HC blends account for almost half of the HC propellant market. The most common
blends are A-70 and A-46, which are propane and isobutane mixtures. Table 2-2 shows
T
the most common HC propellant blends and their market shares.
In conclusion, HC propellants are used in aerosol products because they have the
properties that allow the manufacturer to achieve a wide variety of results. They can be
2-10
-------
TABLE 2-2
TYPICAL HC PROPELLANT PRESSURES AND MARKET SHARES3
Propellant
Isobutane
(A-31)
Propane/Isobutane
(A-46)
Propane/Isobutane/
n-Butane (PIN-46)
DME
(A-63)
Propane/Isobutane
(A-70)
Propane/Isobutane/
n-Butane (PIN-70)
Propane
(A- 108)
Blend
(mol %)
100
19/81
27/29/44
100
50/50
55/18/27
100
Pressure Market
(psig @ 70°F) Share (%)
31 5-10
46 5-10
46 *
63 2-3
70 5-10
70 *
108 10-15
PIN-46 and PIN-70 together account for approximately 2/3 of the market
2-11
-------
used alone or as blends to provide specific pressures. They can be used with foods and
personal care products because they are nontoxic and odorless. With a price range from
$0.19 to $0.38 per pound, plus freight, they are very cost effective. When a water
soluble propellant is desired, DME can be used. In general, the HC propellants are the
most versatile propellants and enable the marketer to deliver the most efficacious and
cost-effective products. Their primary disadvantage is that they are VOC's and
contribute, to some degree, to formation of tropospheric ozone.
2.3.2 Non-VOC Compressed Gases
Compressed gases (e.g., CC>2, N2O, N2, and air) are used as propellants for
some aerosol products. One company is experimenting with using hydrogen as a
compressed gas. These gases are not VOC's and are not considered photochemically
reactive. It may appear advantageous, with respect to air quality concerns, to replace HC
propellants with non-VOC compressed gas propellants. However, in a typical direct
replacement formula, the compressed gas is present in small amounts (2 to 4 percent),
and the remainder of the formula must include additional VOC's which may have a
o
higher ozone formation potential than the original HC propellant. This is because the
HC propellant is an integral part of the product formulation and generally functions both
as a propellant and a solvent. Consequently, removal of the HC propellant must be
accompanied by addition of a solvent.
Compressed gases are defined as "high-pressure propellants that must be injected
sj
into the aerosol container in gaseous form instead of as a liquid under pressure. "L A
compressed gas differs from a liquid HC propellant in that the vapor pressure of the HC
propellant remains constant (at a given temperature) as long as there is liquid propellant
in the container. When a compressed gas is used, the can pressure decreases as the
contents of the can are expelled. As the volume of head space in the can becomes larger,
the pressure decreases. Since the pressure decreases as the product is used, the filler
must "over-charge" the can to ensure that the system will provide sufficient pressure to
expel the entire contents.
2-12
-------
Although compressed gases cost substantially less than HC propellants ($0.03 to
$0.10 per pound versus $0.19 to $0.38 per pound, plus freight), their use results in no
cost advantage over HC propellants. In most cases, replacing the HC propellant with a
less costly compressed gas would not reduce total product cost. For example, in a
formula which uses a 3 percent CC»2 fill to replace a 25 percent HC propellant fill, the
remaining 22 percent volume must be replaced with a solvent to achieve desired spray
characteristics. The cost of the solvent would be greater than that of the HC propellant.
Several concerns must be addressed when considering switching from a HC
propellant to a compressed gas. Some concerns are related to the pressure characteristics
of compressed gas propellants, while other problems arise because of the properties of the
compressed gases themselves.
One concern is directly related to product performance. As the product is
expended and the internal pressure decreases, the spray pattern can deteriorate. This may
be a significant issue because many aerosols are marketed by their spray pattern charac-
teristics. For example, wasp and hornet spray products must be capable of delivering a
stream of insecticide at a range of 16 to 20 feet. If a compressed gas were to be used,
the pressure may not be consistent enough to provide the required stream of insecticide
over the life of the product. To overcome this problem, the can would have to be
pressurized enough to be able to deliver the product at these distances when nearly
empty; however, with this degree of over-charge, the higher pressure would cause the
stream from a full can to break up and extend to only 6 or 7 feet.
Another problem is that compressed gases are not compatible with all products
because of their varying solubility. Both CO2 and N2O are soluble in water. Water and
CC>2 can react to form carbonic acid which will severely corrode a metal container. This
kind of problem makes the use of compressed gases unsuitable for water-based
formulations such as paints, hard surface cleaners, and other products.
2-13
-------
Another limitation of compressed gases is that, because the can must be initially
more highly pressurized than when using a HC propellant, a thicker-walled and more
expensive can must be used to satisfy DOT requirements. This increased container cost
results in a less cost-effective product.
Another disadvantage of compressed gases is that aerosol products propelled by
compressed gases generally cannot be used in an inverted position. Actuation of the
valve with the can inverted so that the end of the dip tube is in the head space would
result in the compressed gas escaping, leaving no propellant to expel the remaining
contents of the can. This would severely affect the performance of products such as
insect repellants, carpet cleaners, and hard surface cleaners which are discharged
routinely in an inverted position. Although valves do exist that will allow for inverted
operation, they are substantially more complicated and more expensive than the
conventional valves now in general use.
It is apparent that manufacturers cannot switch to compressed gas propellants for
all applications. Each category of consumer products must be evaluated individually to
determine whether compressed gas technology would be suitable for specific products.
Currently, only 7 to 8 percent of the aerosol market uses compressed gases. This
percentage could only be increased to 12 to 18 percent with existing technology.
2.3.3 Fluorocarbons
Fluorocarbons, specifically CFC's, have been used as aerosol propellants for
many years. These chemicals are nontoxic and nonflammable, which makes them
attractive for use in aerosol consumer products. However, the use of these compounds in
most aerosol propellant applications was banned in the United States in 1978 because of
their potential to deplete the stratospheric ozone kyer. The "Montreal Protocol on
Substances that Deplete the Ozone Layer," a protocol to the "Vienna Convention for the
Protection of the Ozone Layer," has been ratified by 65 countries and calls for a
2-14
-------
reduction in the production and consumption of CFC's. The Clean Air Act Amendments
of 1990 (CAAA) require a phaseout of most CFC production by the year 2000.
Since CFC's are being phased out of production, HCFC's are being used as
substitutes in some cases. Currently, the HCFC's in use are HCFC-22 and HCFC-142b.
Three other HCFC's, HCFC-123, HCFC-124, and HCFC-1416 are under development.
Because these compounds still contain chlorine, the principal culprit in destroying ozone,
the Montreal Protocol limits their production to 1986 production levels. Furthermore,
the CAAA will prohibit the use of HCFC's in virtually all applications beginning in
2015, with a complete phaseout of HCFC production by 2030. Therefore, for all
practical purposes, CFC's and HCFC's are not viable long-term alternatives to HC
propellants.
Another class of fluorocarbons, the HCFC's, can be used as propellants for
aerosol consumer products. These compounds contain no chlorine; therefore, they have
no potential for stratospheric ozone depletion. Currently, the only HFC commercially
available is HFC-152a. Two additional HFC's that are being developed are HFC-143a
and HFC-125. Table 2-3 presents the properties of the HCFC's and the HFC that are
currently available.7'° The primary disadvantage of HCFC's and HFC's is that their
cost is as much as 20 times that of HC propellants.
2.3.4 Propellant Blends
While HC propellants (Section 2.3.1) are mixed to meet specific pressure
requirements, other propellant blends have been formulated to maximize the desirable
characteristics and minimize the drawbacks of particular propellants. For example, a
blend of a flammable propellant with a nonflammable propellant may result in a
nonflammable blend. Or, a blend of a costly propellant having the required physical
properties can be mixed with a less costly propellant resulting in a more cost-effective
formulation.
2-15
-------
TABLE 2-3
PHYSICAL PROPERTIES OF FLUOROCARBONS7'8
HCFC-22
HCFC-142b
HFC-152a
Formula
Molecular Weight
Vapor Pressure
(psig @ 70°F)
Solubility in Water
(wt % @ 70°F)
Boiling Point
(°F @ 1 atm)
Freezing Point
(°F @ 1 atm)
Flammability Limits
in Air (vol %)
Ozone Depletion
Potential
Greenhouse Potential
(relative to CFC-12
at 1.0)
Photochemical
Reactivity*
CHC1F2
86.5
121
30
-41.1
-256
nonflammable
0.05
0.10
0.0
CH3CC1F2
100.5
29
0.5
15.1
-204
6.3 - 14.8
0.06
0.02
0.0
CH3CHF2
66.1
62
1.7
-11.2
-179
3.9- 16.9
0.0
0.01
0.0
As of December 1991, the EPA had not determined that a suitable relative reactivity
scale was available.
2-16
-------
Propellant blends can be divided into two classes: azeotropic and nonazeotropic.
Nonazeotropic blends are usually less desirable because their properties change as the
propellant is dispensed, in contrast to pure propellants or azeotropic propellant blends.
For example, when a binary (two-component) nonazeotropic blend is discharged, the
more volatile component is depleted first, and the pressure decreases with product usage.
Ultimately, this fractionation process continues until eventually the remaining propellant
consists largely of the less volatile component. This may be a problem if the propellant
blend is designed to be nonflammable but becomes flammable when the can is almost
empty and only the lower-pressure (and flammable) propellant remains. About
20 percent of aerosol products use a valve system with a vapor tap. A vapor tap is a
small hole in the dispensing valve in the vapor space of the aerosol container. This tap
allows vapor to be discharged with the product to give added aerosol dispersion. The use
of vapor tap valves with nonazeotropic blends may cause problems in some cases and the
pressure drop may be more severe.
Despite the potential problems, various formulations using nonazeotropic
propellant/solvent blends have been used. These blends are listed below.
• HCFC-22/HCFC-142b (40/60) - This blend is especially suited for
aerosols in glass bottles because of the moderate pressure of the mixture
(37 psig at 70°F). The other advantages of the blend are that it is soluble
with ethanol, it has a faint odor that does not interfere with fragrances, and
it has a high solvent power. This blend would provide reduced
flammability compared to propellants such as isobutane or DME. As
formulated, the 22/142b blend is nonflammable, but once 70 percent of the
9
blend is discharged as vapor, the remaining blend is flammable.
• HCFC-22/HC - Mixtures of HFC-22 and HC's could possibly provide a
less flammable alternative to HC blends. '* The high vapor pressure of
HCFC-22 results in a relatively rapid fractionation of the nonazeotropic
blend.
2-17
-------
DME/HC — This blend is less expensive but marginally more flammable
than the DME/HFC-152a blend.10'12
• HFC-152a/HC — This blend provides unique foam properties (improved
cell structure) in products such as hair mousses. In addition, its low
flammability characteristics have been valuable in indoor insect foggers.
• HFC-22/Methyl Chloroform — This nonflammable system is used with the
newer insecticides and insect repellents. °
• DME/Water ~ New technology has been developed for water-based insec-
ticides.10 This low-cost nonazeotrope could be used for other water-based
formulations.
CFC-12/113/114/HC - This blend has been used in tire inflators.
10
There are several azeotropic propellant blends reported that avoid potential
problems with fractionation and changing composition. These propellant blends offer the
possibility of tailoring the properties of solvency, pressure, and flammability. Azeotropic
propellants can utilize vapor tap valves that allow inverted use and improve droplet
breakup.
• HFC-152a/DME C30/70) - This blend is flammable. It has a wide range
11
of applications due to its range of solubility in water.10
• HCFC-22/DME - Nonflammable and flammable blends exist. The blend
must have 12 percent or less DME to be nonflammable.
• HCFC-22/Propane (68/32) - This is a flammable blend and a high-boiling
point azeotrope (higher vapor pressure than HCFC-22 alone).
2-18
-------
• CFC-12/DME -- The 90/10 blend is nonflammable and is used in foam
insulation and caulking. ^'*4
• CFC-12/HFC-152a (known as "R500") (73.8/26.2) -- This blend is
nonflammable and has a relatively high vapor pressure.
• HFC-152a/Isobutane (75/25) ~ This blend is flammable and has a vapor
pressure of 72 psig at 70°F.15
2.3.5 Summary of Propellant Selection Considerations
Any change in the propellant used for a specific product must be carefully
considered. The pressure of the propellant must be matched to the desired spray
characteristics. The flammability of the propellant must be considered. The role of the
propellant in the formulation must be matched with the attributes of the propellant, and
water solubility must be considered. With all these variables, it is critical that the effects
of any changes be understood so that the final product will be safe and marketable.
2.4 AEROSOL VALVE ASSEMBLY
This section describes the various valve components and the general types of
valves. Most aerosol valve assemblies consist of 7 components: actuator, mounting cup,
stem, stem gasket, spring, body (or housing), and dip tube. Figures 2-2 and 2-3 are
diagrams of a vertical action valve. In general, the valve opens when a downward force
is applied to the actuator, and it closes when the force is released. There are several
different kinds of valves: vertical valves, tilt valves, female valves, "total release" valve
systems and other special application valves. Valves must be designed to perform
specific functions. Many aerosol products must deliver a fine spray. For these products
the valve must be designed to break the liquid up into small particles. Products that are
to be sprayed on a surface, whether it be a hard surface (paint) or the body (underarm
deodorant), must have a valve that optimizes transfer efficiency. Some other types of
2-19
-------
valves include metering valves (dose inhalants), inverted use valves (compressed gases)
and total release valve systems (indoor foggers), female valves (paints), and tilt valves
(starches). In addition to the different valve types, there are over 300 varieties of valve
bodies, a wide variety of stem gasket materials, 6 different sizes of valve springs, 5
variations of dip tubes, 2 materials for valve cups, and several types of valve gaskets.
Each combination is designed to fulfill a set of specific functions.
2.4.1 Vertical Action Valve
With a vertical action valve, the product is dispensed when the consumer pushes
down on the actuator which, in turn, presses down on the valve stem (see Figure 2-3).
The stem gasket covers the hole in the narrow portion of the valve stem. Figure 2-2
shows the hole in the valve stem. The outside edge of the stem gasket is trapped between
the body (housing) and the mounting cup (see Figure 2-3). When the stem is forced
down, the inside edge of the stem gasket is bent, and the hole in the stem is opened to
the product reservoir in the body. The product is then free to flow into the stem through
the actuator and out of the can.
2.4.1.1 Actuator
The actuator is designed to operate the valve and regulate the spray rate, spray
pattern, and particle size. Some actuators provide a direct flow path for the product.
Other actuators have a mechanical breakup (MBU) system, consisting of swirl chambers
and bends in the flow path, to mechanically enhance the breakup provided by the
propellant. Some products, such as starches and other high-water-content products, could
not be marketed as aerosols without an MBU to break up the solid stream of liquid.
Various MBU's are available, and by selecting the correct MBU, the manufacturer or
marketer can choose the desired spray characteristics for the specific product.
2-20
-------
ACTUATOR
MOUNTING CUP
DIP TUBE
STEM
Hole in Valve Stem
STEM GASKET
SPRING
BODY
Figure 2-2 Components of the Precision Vertical Valve
2-21
-------
(flUJX —> IQ
, , , ~>-UI_
I
s
'€
o
-------
2A. 1.2 Mounting Cup
The outside edge of the stem gasket is clamped between the mounting cup and the
valve body, keeping the stem gasket in one place. The mounting cup also serves as the
hermetic seal to the 1-inch hole in the aerosol can. Mounting cups are available in
conical and flat cup shapes (see Figure 2-4). The conical profile is used to elevate the
actuator to allow a wide-angle spray to clear the edge of the mounting cup and to increase
the strength of the mounting cup. The underside of the mounting cup may be lined to
protect the metal from the product.
2.4.1.3 Valve Stem
The valve stem serves as the product flow regulator. The product passes through
the orifice in the neck of the valve stem, through the large opening at the top of the stem,
and then finally into the actuator. The orifice size can range from 0.01 to 0.05 inches.
Smaller orifices are prone to plugging. Larger orifices weaken the valve stem, and the
risk of breaking the stem increases. Stems are also marketed in different lengths so that
the height of the actuator above the mounting cup can be regulated.
2.4.1.4 Stem Gasket
The stem gasket is designed to fit around the neck of the stem and seal the stem
orifice so that the product is contained while the actuator is not depressed. The stem
gasket is made of a flexible material so that, when the actuator is depressed, the gasket is
bent and the orifice is exposed to the product. The manufacturer or marketer has to
make sure that the material of the stem gasket is compatible with the product formulation.
If the gasket deteriorates or swells, the product may leak out of the container.
2-23
-------
FLAT CUP
CONICAL CUP
Valve Body
T I
Figure 2-4 Cross Section of Typical Flat Cup and Conical Cup Valves
2-24
-------
2.4.1.5 Valve Body
The primary purpose of the valve body, or housing, is to provide an enclosure for
the spring to force the stem up against the stem gasket when the actuator is released.
The bottom portion of the body has an extension that fits into the dip tube. Product
flows from the dip tube into the reservoir, then is forced through the stem orifice when
the actuator is depressed. Some valve bodies have a vapor tap, a hole that is exposed to
the head space in the can (see Figure 2-2), to allow propellant vapor into the liquid
stream to produce greater breakup and a lower delivery rate.
2.4.1.6 Dip Tube
The dip tube serves to transfer the product to the valve body and to act as a flow
metering device. The larger the diameter of the dip tube, the more product is delivered
to the valve body. Other factors affecting dip tube selection include can size, curvature,
and tube material.
2.4.2 Tilt Valves
Tilt valves (Figure 2-5) differ from the vertical valve in that the consumer applies
a lateral force to bend the stem gasket so that the orifice is opened and the product can
flow. The force required to activate the flow of the product is generally less than the
force needed to activate the vertical valve assembly. This type of valve is desirable
where misdirection of the spray could be a problem. The spray will go in the direction
that the valve is pushed. The main problem with this type of valve is that the gasket has
more contact with the product than with a vertical valve; therefore, the gasket material
must be compatible with the product formulation so that the gasket does not swell or
deteriorate.
2-25
-------
ACTUATO*
SPUING CUP
(STEM SEAT)
MOUNTING CUP
GASKET
BODY
STEM
/ MOUNTING CUP
STEM GASKET
STEM OKIfICES
SPRING
\-DIP TUBE
STEM
OWICES
CLOSED
OPEN
Figure 2-5 Cross Section of a Typical Tilt Valve
2-26
-------
-ACTUATOR
MOUNTING CUP
GASKET (INTERNAL)
-SEAT
-SPRING
-BODY
-DIP TUBE
Figure 2-6 Typical Female Valve
2-27
-------
2.4.3 Female Valves
Female valves (Figure 2-6) differ from the typical male valve in that the valve
stem is part of the actuator. The actuator stem is inserted into the mounting cup hole.
To activate the valve, the actuator is depressed vertically as in a normal male vertical
valve. The primary use of the female valve is for products that will dry out or clog the
orifice in the valve stem. The valve stem of a female valve is an integral part of the
actuator and can be removed for cleaning. This is especially useful for aerosol paints and
other coatings.
2.4.4 Total Release Valve Systems
A total release valve system is designed to stay open until the entire contents of
the can are released. The actuator is fitted with a locking device that ensures that all of
the product is expelled. The principal application for this type of valve is for insect
foggers.
2.4.5 Summary of Valve Selection Considerations
Many different variables must be considered when deciding which valve is best
suited for a specific application. The formulation must be tested to determine if it is
compatible with the stem gasket, dip tube, valve body, and mounting cup. The
manufacturer must also know what specific spray characteristics are desired so that a
choice of MBU, orifice size, and dip tube diameter can be made. If the product is prone
to clogging, a female valve may be the best choice for the product. There are hundreds
of different permutations of valve components, and the marketer and manufacturer must
select a combination that will ensure that the specific product performs optimally.
2-28
-------
2.5 AEROSOL CONTAINERS
The container is a critical component of an aerosol consumer product because it
must withstand the pressure of the product formulation and propellant without bursting or
leaking. It is also the portion of the product that the consumer sees when making a
decision to buy a particular product. Therefore, it must be attractive and cost effective.
Aerosol product marketers must consider each of these aspects of can design in order to
choose a can that will be best suited to a specific application.
2.5.1 Regulatory Concerns
The DOT is responsible for regulating the transportation of hazardous materials.
Almost all aerosol products are classified as materials presenting a limited hazard during
transport due to their form, quantity, or packaging. The Code of Federal Regulations,
Title 49, Part 173.306 (49 CFR Part 173.306) governs the shipment of most aerosol
products. These regulations dictate the type of packaging that can be used (transported)
based on the pressure of the product.
The pressure rating for metal cans is based partly on the thickness of the ends of
the can because these are the pieces most likely to fail. The 3 principal types of metal
aerosol cans are "nonspecification" (2N), 2P, and 2Q. Table 2-4 presents the DOT
requirements for metal thickness, pressure resistance without burst, and product pressure
for each of these containers. The last column gives the maximum product
pressure (at 130°F) allowed by DOT for each type of can. This upper limit is well
below the minimum burst pressure. Each successive can type, 2N, 2P, and 2Q,
respectively, can withstand higher product pressures before a failure occurs.
If the product has a pressure greater than 180 psig, the regulation allows for the
use of a "specification 39" metal container. It does not have specific pressure or burst
limitations. Instead, it is designed using a stress formula to determine the safe internal
pressure for a given wall thickness. This allows for a wide range of product pressures
2-29
-------
TABLE 2-4
DOT REQUIREMENTS FOR METAL AEROSOL CONTAINERS5
Minimum Pressure
Minimum Resistance Maximum Product
DOT Metal Thickness Without Burst Pressure
Specification (inches) (microns) (psig) (psig at 130°F)
"Non-spec" none none 210 140
(2N)
2P 0.007 178 240 160
2Q 0.008 203 270 180
39 variable variable * *
Burst pressure and maximum product pressure are determined by stress formula.
2-30
-------
and diverse applications ranging from hair sprays to cruise missile containers. A general
DOT exemption applies to containers of not more than 4 fluid ounces in overflow
capacity. Bottles larger than this may be shipped interstate if pressures do not exceed
40 psia at 70°F, 104 psia at 130°F, or 40 psia at 100°F for flammable products. This
regulation effectively eliminates from interstate shipment (without a special exemption)
glass aerosols containing HC's and having more than a 4-ounce capacity. The DOT
regulations also do not distinguish between coated and uncoated containers (see Section
2.5.3).
2.5.2 Metal Can Construction
Design considerations for aerosol containers must include strength of the material,
compatibility with the product, cost effectiveness, and attractiveness to the consumer. To
satisfy these criteria, the aerosol consumer product industry uses three-piece tinplate cans
for most products. The three-piece can consists of a bottom endpiece, a top endpiece or
dome, and the main body. Each of these components is designed to fulfill a specific
purpose. The bottom endpiece is designed as a concave disk to withstand the internal
pressure of the propellant. The purpose of the dome (shown in Figure 2-7) is threefold.
It has a conical shape to withstand high pressures, a 1-inch hole in the top to hold the
valve, and a vertical section to hold the cover cap in place. The main body is cylindrical
in shape. The primary consideration when designing the main body is the desired
package size and geometry. These characteristics should be consistent with the intended
use of the product. For example, a small can (small main body) will hold less volume
and, in turn, can be used for fewer product applications. A larger container can contain
more of the formulation (i.e., more applications) but the larger size makes the aerosol
can more difficult to handle.
The first step in manufacturing tinplate (or tin-free) containers is making the steel.
The raw materials needed for the steel manufacturing are: iron ore, coke, and Limestone.
About 25 percent of the iron is obtained from recycled scrap material. These materials
are combined in a basic oxygen furnace and molded into either continuous slabs or
2-31
-------
r hole for valve
Vertical section for
cover cap
Figure 2-7 Cross Section of a Typical "Snap-Lock" Dome Top
2-32
-------
ingots. The steel is then tempered for hardness and then annealed for stress reduction.
The next step is to roll the steel to the desired thickness and to coat or line the steel. The
steel has to meet specifications for strength, surface treatment (e.g., tinning, lubrication,
etc.), and corrosion potential. Usually, surface characteristics and corrosion potential are
adjusted by lining the tinplate or tin-free steel can. This protects the metal from damage
by the product formulation. Linings include epoxy materials, vinyls, and vinyl
organisols. There are at least 9 specific lining types used for aerosol cans. The type of
lining used for a specific product depends on how the can material or the lining will react
with the specific formulation. Products that have a high water content need a lining that
retards rust. Products that are relatively inert may not need a can lining. The
development of a lining includes laboratory testing of the material, plant trials to
determine how the lining will act during the can manufacturing process, and, finally,
commercialization of the lining. Lining development requires 18 months to 2 years from
initial development to commercialization. This time delay can be important, especially
since new formulation requirements, such as a water-based formulation, may require the
development of a new lining to protect the can.
Can manufacturers receive sheets of tinplate or tin-free steel already lithographed
with the can design and with a protective lining if required. After the metal sheets are
received, they are cut into individual can sizes. In order to produce high quality cans at
high speeds, the pieces must be cut within 1/1000 of an inch of the desired size. These
individual rectangles are then fed into a machine that rolls the can into the cylindrical
shape and welds the two endpieces together. The diameter of the main body is usually
the critical dimension when designing a can manufacturing operation. Changing the
diameter of a can requires either a separate machine or modification of existing
equipment. Therefore, manufacturers have standardized the can sizes available for
aerosol consumer products.
The can size is identified by both the diameter and the height of the can. The
diameter is measured across the bottom of the can, and the height is measured from the
base to the top of the top double seam where the dome cap meets the main body of the
2-33
-------
can. The dimensions are reported as a 3-digit number. The first digit is the number of
inches and the last two digits are the number of sixteenths of an inch. A 211 x 908 is a
can with a diameter of 2 11/16 inches and a height of 9 8/16 inches. Table 2-5 shows
the dimensions of some of the cans marketed by United States Can Company. °
The next step after rolling and welding is to pass the can cylinders through a
flanger. This device bends (or flanges) the top and bottom of the cylinder so that the
endpieces can be fastened on in the crimping step. After the flanging step, the cans are
top seamed and tested for leakage by pressurizing the cans with water.
Separate machines press the endpieces (tops and bottoms). Depending on the
shape of the endpiece, the pressing is done in several stages. For bottom endpieces, the
pressing is done in one or two stages. For dome tops that have a more complex shape,
the pressing is done in six stages. This shape includes a 1-inch hole for insertion of the
valve piece (see Figure 2-4). The next step in can manufacturing is to double seam the
endpieces onto the can body. The seaming process presses the lips from the endpieces to
the flange on the main body to form a tight seal. This step is important because an
incorrect seam will cause a can to fail when it is filled. A loose seam may cause the end
piece to separate from the can body due to the nigh internal pressure of the product. An
excessively tight seam may cause the metal to fail, again resulting in separation of the
endpiece from the body when pressurized.
Can manufacturers may conduct over 80 different checks on the cans during and
after the manufacturing process to ensure that all specifications are met. The checks can
be as simple as a visual inspection or as complicated as high-pressure tests in which
water is forced into the cylinder of the main body which is then checked for leaks and/or
buckling. Another check consists of a statistical sampling of cans from the manufacturing
line to inspect the top and bottom crimps. The crimps are observed under high-powered
microscopes to determine if they are too loose or too tight. If any of the numerous
checks show that the cans being produced are inferior or will not meet specifications, the
lines are shut down and the problem identified and corrected.
2-34
-------
TABLE 2-5
CAN SIZES MARKETED BY UNITED STATES CAN COMPANY18
Size
202 x 214
202 x 314
202 x 406
202 x 509
202 x 700
202 x 708
207.5 x 605
207.5 x 701
207.5 x 708
211 x413
211 x604
211 x612
211 x713
211 x908
300 x 709
Brim Full Capacity
5.0 oz
6.8 oz
7.8oz
9.9 oz
12.5 oz
13.4 oz
15.3 oz
17.1 oz
18.2 oz
13.9 oz
18.0 oz
19.5 oz
22.6 oz
27.4 oz
26.9 oz
2-35
-------
After all the final checks are done and it is determined that a can meets the
required specifications, it is packaged and shipped to the product filler. The
manufacturer/ marketer determined the size of can, the lining, and the lithography when
the order was placed. The last step of filling the can and getting the final product to the
marketplace is performed by either the marketer or a contract filler.
2.5.3 Glass Container Construction
Glass aerosol bottles are used primarily for fragrance products and
Pharmaceuticals. Glass containers account for only approximately 0.5 percent of aerosol
consumer product production. The primary differences between aerosol and other types
of glass packaging, such as pump sprays, is that the containers are restricted! to smaller
bottle sizes and less complicated shapes due to the high internal pressure of aerosols. A
major concern in glass aerosol packaging is that of safety. Even though most glass
bottles can withstand internal pressures well in excess of those needed for aerosol
products, pressures are kept substantially lower, typically around 20 psig at 70°F. This
reduces the risk of injury to the consumer. As added protection, more than 60 percent of
all glass aerosols are plastic coated. This coating prevents personal injury from glass
fragments if the bottle should rupture, and helps prevent injury due to ignition of the HC
propellant by containing the bottle contents when ruptured.
The design of glass aerosol bottles must therefore consider geometries that have
high impact resistance and pressure tolerances, and shapes that allow good glass
distribution and strain elimination. For glass aerosol bottles produced in the United
States, there is essentially one standard neck finish, tapered with a lip where the valve
will be crimped into place. The neck has been standardized so that standard aerosol
valves can be used. The bottle itself may have a flat wall surface or added surface
features such as swirls or ribs.
The manufacture of glass aerosol bottles begins with blow-molding of molten glass
into the desired shape of the container. The glass cools immediately, inducing stresses in
2-36
-------
the outer layers. These stresses must be alleviated to prevent the production of a
defective bottle unable to withstand the internal pressures required. This is done through
an annealing process.
The bottle might also be subjected to a surface toughening process known as "hot
and cold end" treatment. This produces a skin of metallic dioxide that is substantially
harder and tougher than the underlying glass. For best results, the oxide film is sprayed
with a lubricant as the bottle leaves the cold end of the annealing lehr. The
oxide/lubricant film helps prevent scratching and reduces environmental changes of the
glass surface. One adverse effect of this treatment is that it may cause loss of adhesion
between paper labels and siliconized glass bottles.
One purpose of the plastic coating is to provide protection from ultraviolet light.
Coatings also protect the bottle from rough handling by increasing impact resistance.
Plastic coatings also improve product aesthetics, provide special surface effects (high or
low gloss, variegated colors, etc.), and allow safe utilization of pressures over 20 psig at
70°F and larger sizes up to 4 ounces for flammable compressed gases. The plastic
coatings are applied by dipping the glass container into a bath of polyvinyl chloride. This
dipping process is then repeated to form a soft covering high in tensile strength and with
good impact absorption. The dipping and fusing cycles must be carefully controlled to
produce optimum thicknesses and physical properties.
The finished bottles are then sent to the filling lines where the product is
introduced into the bottles, and excess air is removed. As much air as possible must be
removed to prevent an increase in the pressure and possible reactions with the product.
The filled, purged bottles are then hand-fitted with a valve that is crimped onto the neck,
creating a hermetic seal. Because coating thickness and bottle neck diameters vary, the
optimum crimp diameter must be determined for each lot of glassware. This reduces the
chance of obtaining a bad valve seal resulting in a leak. The bottles are then gassed and
checked for leaks. Finally, glass aerosol bottles may be given a variety of finishes.
They can be coated to provide a sheen, iridescence, and metallic or colored finish. They
2-37
-------
can be silk-screened, decorated by hot stamping, or paper or foil labels applied to the
bottles. Composite containers, in which the glass bottle is inserted into an aluminum tube
for example, can also be used.
The typical glass manufacturer follows a quality assurance program consisting of
visual inspection, statistical inspection and attribute inspection. Visual inspections occur
throughout the manufacturing process to detect defective or damaged bottles. There are 5
types of statistical inspections and 4 different attribute inspections performed throughout
the process. As a result, glass aerosol containers have a safety record better than that of
metal aerosol containers.
2.5.4 Plastic Container Construction
Plastic aerosol containers do not yet appear to be a viable alternative to the other
two aerosol container types. There are many factors that must be considered when
selecting the plastic to be used. These include high mechanical strength without
brittleness; excellent chemical, creep, and permeation resistance; adaptability to
production technology (injection molding, ultrasonic welding, etc.); design flexibility; and
cost. It is difficult to find a single plastic that can meet all of these requirements. There
are, however, 2 plastics being used on a much smaller scale than metal or glass aerosol
packaging.
The design of plastic aerosol containers lends itself to a variety of shapes and
sizes. For the most economical packages, the following attributes are recommended:
cylindrical shapes, curved side walls, and embossed effects less than 0.010 inches deep.
The most efficient shape would be a perfect sphere. Deviations from the sphere require
more material to be used to compensate for increased stresses in the plastic.
Plastics also give added flexibility with respect to the type of neck opening. Any
of the standard neck openings can be molded or post-machined on the containers. Valves
2-38
-------
are typically attached by ultrasonic welding that eliminates any contact between metal or
rubber parts and the product.
The base design of the plastic container is the most critical because this area is the
least resistant to impact. Recommended features include a wall tapered into the base,
inverted truncated and conical-shaped base, and the use of extra material. Separate snap-
on base sections can also be used to reduce the effect of impact. In general, the impact
resistance of plastics far exceeds that of glass aerosols and most plastic-coated glass
aerosols.
Safety concerns associated with plastic aerosols are minimal. Plastic does not
shatter as does glass but usually breaks into two or three parts or develops a split. If the
plastic does break, the pieces will fly outward due to the pressure release, but they do not
present a large hazard because they are lightweight and are not sharply pointed. Plastics
involved in a fire will melt and allow the pressurized product to be released gradually
rather than explode. The low thermal conductivity of plastics prevents the build-up of
extremely high internal pressure before softening can occur.
There are several problems with plastic aerosols not prevalent in metal or glass
packaging. Many of the aerosol formulations contain darkly colored materials and will
stain plastic containers. Internal linings or colored bottles can be used for these
formulations. Storage of many scented products in unlined plastic containers results in
odor stability problems. Another problem lies in the fact that all plastics can be
permeated. Permeation is a function of the material, wall thickness, surface area, and
temperature. Pressures involved in aerosol packaging have little effect. Many plastics
are highly permeable to the HC's used as aerosol propellants. Finally, plastics are
susceptible to adverse affects by organic solvents, and strong acids and bases. Plastics
can be weakened or even dissolved by prolonged contact with many of these types of
chemicals. Therefore, special compatibility tests on new formulations must be conducted
for plastic aerosols. However, the time commitment for these studies is probably not any
greater than similar development studies for the other packaging types.
2-39
-------
2.6 REFERENCES
1. Letter from J. Graf, Cosmetic, Toiletry, and Fragrance Association, to B.
Moore, U.S. EPA, October 17, 1991.
2. Johnsen, M., The Aerosol Handbook, 2nd Edition, The Wayne Borland
Company, Mendham, New Jersey, 1982.
3. Meeting of National Aerosol Association and U.S. EPA, Office of Air
Quality Planning and Standards. Durham, North Carolina. May 7, 1991.
4.
5. Meeting Summary, National Aerosol Association participation in EPA's
Aerosol Products Study, U.S. EPA, Office of Air Quality Planning and
Standards, Durham, North Carolina, July 2, 1990.
6. Teleconference between B. Broberg, Radian Corporation, and M. Johnsen.
September 10, 1990.
7. Montford Johnsen. "The Fluorocarbons - Old Problems and New
Opportunities." Aerosol Age, January 1991.
®
8. DuPont DYMEL Aerosol Propellant Systems Technical Manual.
9. Strobach, D.R., "Update on the Fluorocarbons (Part JJ), CFC Propellants
Today." Aerosol Age, July 1988.
10. Daly, J.J., "Emerging New Propellant Blends." Aerosol Age, October
1986.
11. Dunn, D.P., "New Propellants Respond to Regulatory Developments."
Aerosol Age, January 1988.
12. "DuPont Talks About Its DME Propellant (Part I)." Aerosol Age, June
1982.
13. Sterling, J.D., "Fluorocarbon and Dimethyl Ether Aerosol Propellants."
Aerosol Age, December 1982.
14. Bohnenn, L.J.M., "An Innovative Azeotropic Propellant Blend." Aerosol
Age, November 1987.
15. "DuPont's Sterling Updates Propellant 152a." Aerosol Age, July 1981.
2-40
-------
16. Chemical Specialties Manufacturers Association, Aerosol Products
Workshop Conducted for U. S. Environmental Protection Agency.
October 24, 1990, Research Triangle Park, North Carolina.
17. "Aerosol Product Innovation Fueled by Public Attitudes, Regulations."
Chemical & Engineering News, April 23, 1990.
18. United States Can Company, marketing literature.
2-41
-------
SECTION 3.0
CHARACTERIZATION OF THE AEROSOL PRODUCTS INDUSTRY
3.1 INDUSTRY HISTORY AND DEVELOPMENT
Aerosol products existed as early as the 1860's, with the first known aerosols
being milk products and other beverages which were dispensed hi aerated form through
the use of carbon dioxide as a propellant. About 1910, cans and glass tubes of ethyl
chloride were sold as topical anesthetics that chilled the skin prior to minor surgery. The
most significant early work in aerosol product development was done in 1922, when Eric
Rotheim of Norway developed an aerosol package comprised of a heavy brass shell and a
primitive, threaded valve. Propellants for these early systems included isobutane, vinyl
chloride, carbon dioxide, methyl chloride, and dimethyl ether. No further development
of the aerosol packaging concept occurred until 1943, when U. S. Department of
Agriculture researchers (Lyle Goodhue and William Sullivan) developed an insecticide
"bomb" for use by U. S. troops in the South Pacific islands. Over 30 million of these
units were produced from 1943 to 1947. These products utilized CFC propellants which
were developed during the 1930's by Thomas Midgley of DuPont. Hydrocarbon
propellants came into limited use in 1954, when Phillips Chemical Company introduced
essentially odorless "Pure Grade" propane and butanes, and Risdon Manufacturing
Company developed the first reliable mechanical breakup valve.
The aerosol industry continued to use CFC's as the propellants of choice for most
applications through the mid-1970's. With the advent of the Rowland and Molina ozone
depletion theory which was published hi 1974, the industry began converting to HC
propellants. In 1975, approximately 50 percent of all aerosols were filled with HC
propellants. By 1978, when CFC's were banned by the EPA and the FDA for use in
most aerosol products, the conversion from CFC's to HC's was virtually complete. This
conversion was costly to the aerosol industry because many existing plants were not
designed to handle flammable propellants. To convert from CFC propellants to HC
3-1
-------
propellants, the aerosol industry incurred over $200 million in capital expenditures.
Furthermore, the growth of the aerosol industry was hindered because of consumers'
perceptions about the adverse environmental effects of CFC's, even though nearly all
post-ban aerosol products were propelled by HC's instead of CFC's. The number of
aerosol units filled dropped from 2.9 billion units in 1973 to approximately 1.5 billion
units annually between 1976 and 1980. The aerosol industry has gradually recovered and
has reported growth in the number of units filled each year since 1982, with nearly 3
-7
billion aerosol units being filled in the United States in 1989. Currently, approximately
80 percent of all aerosols are HC-propelled. The few remaining CFC-propelled aerosols
(approximately 2 percent of the market) are those permitted by exclusion or exemption
(e.g., specific pharmaceutical, military, and aviation products) or those that are not
regulated. The overall growth of the industry is attributed to new product introduction
in the household products area, as well as continued growth in the use of aerosol
automotive and industrial products.-*
A significant activity of today's aerosol industry is consumer education. Many
consumers continue to believe that most aerosol products are propelled by CFC's and,
therefore, contribute to stratospheric ozone depletion. One industry organization, the
Consumer Aerosol Products Council (CAPCO), has produced an educational video, "The
Aerosol Adventure — How Tech Makes It Tick," that explains aerosol technology to a
target audience of sixth to ninth grade students.
3.2 STRUCTURE OF THE INDUSTRY
The aerosol industry cannot be defined by a single, uniform structure. Some
companies perform multiple functions such as research and development, product
formulation, can and valve design, propellant refining, container filling, and marketing.
Other companies may perform only one or two of these functions. The aerosol consumer
products industry presently employs approximately 20,000 persons directly, with an
additional 80,000 persons being employed indirectly. The following sections describe
3-2
-------
the primary elements of the aerosol industry: marketers, fillers, formulators, propellant
and raw material vendors, container manufacturers, valve suppliers, and cover cap
manufacturers.
3.2.1 Marketers
Aerosol product marketers promote and sell thousands of different products to
consumers. Marketing strategies are affected by research, manufacturing development,
packaging requirements, and economic factors. Marketers develop specifications for
products based on consumer preferences, feasibility, and costs. Once a new product is
developed, actual production can either be contracted out, performed in-house, or both.
For instance, a marketer may produce formulations and perform the filling in-house, but
contract out the container and valve manufacturing processes. When the work is
contracted out, the filler, valve and container manufacturers, and propellant supplier
provide the services required to produce each specific product. There are reportedly 500
marketers currently in the United States. Approximately half of these companies employ
contractors to do their filling. About 25 percent of the marketers do their own filling,
5 percent fill their own cans as well as those of others, and 20 percent both fill their own
and contract out the filling operation. '-* While most of the decisions concerning the
valve, the container, and the formulation (propellant and product) are made by the
marketer, these choices are ultimately influenced by the consumer. Consequently, most
companies in the aerosol industry simply produce the products according to the
i -^
marketer's specifications. '
Marketers have various perspectives on product introduction and improvement.
Some are interested in marketing high-volume, routinely used products, while others hope
to capture specialty markets. Other firms may command a small share of a major market
such as hair sprays. These diverse goals require that fillers and valve and container
manufacturers be prepared to deliver a wide range of goods and services tailored to
individual marketers' unique specifications.
3-3
-------
Most aerosols are sold in supermarkets, mass merchandiser outlets, drug stores,
and hardware stores. The major market categories are personal care products, household
products, automotive/ industrial products, paints and finishes, insect sprays, food
*j
products, and animal products.' In addition to traditional consumer products, a segment
of the aerosol market is comprised of commercial and institutional products. This market
sector represents a diverse spectrum of industries that rely on aerosol products to perform
specific (and sometimes critical) functions. Consequently, these specialty aerosol
products, which are typically not sold in normal consumer outlets, must be considered
individually or as subsets of specific product categories.
3.2.2
Aerosol fillers perform the task of injecting the product formulation (product and
propellant) into the aerosol container and sealing the pressurized container. Aerosol
containers are either filled in-house by the marketer of the product (captive filling), or the
filling operation is contracted out to another company (contract filling). There are
approximately 100 fillers in the United States (Table 3-1). About half these fillers are
contract fillers that fill exclusively for the trade, while the other half fill for themselves as
c Q
well as for marketers. '° The product formulation is usually blended at the same facility
as the filling. Therefore, most fillers are also formulation blenders.
Because some companies fill exclusively for the trade and others fill for
themselves as well as for other companies, it is hard to define a clear relationship
between the fillers and other members of the aerosol industry. It is known, however,
that many contract fillers form one-on-one relationships with formulators aind marketers.
9 0
These relationships create a dependence on the formulator and marketer for business/>?
3-4
-------
TABLE 3-1
U.S. AEROSOL PRODUCT FILLERS8
F Accra-Pac Incorporated
F Accu-Pac
F Advance Aerosol & Chemical Specialties
F Aerofil Technology
F Aerosol Research Laboratories Incorporated
F Aerosol Services Company Incorporated
F Aerosol Specialties Corporation
F Aerosol Systems Incorporated
F Aerosol West
F Aerotech Industries
F,M Aervoe Pacific Company Incorporated
F,M Airsol Company Incorporated
F,M Alberto-Culver Company
F,M Altawood Incorporated
F,M American Gas & Chemical
F,M American Grease Stick
F American Jet Way
F,M Amrep Incorporated
F,M Amway Corporation
F,M Animal Repellents
F Apollo Industries
F Armstrong Laboratories Incorporated
F Barr Company, Division of Pittway Corporation
F Beatrice Cheese Incorporated
F,M Berryman Products
F Bissel Penn Champ Incorporated
F,M Boyle-Midway, Division of American Home Products
F,M Broughton Foods Company
F Carroll Company
F,M Carter-Wallace Incorporated
F Case-Mason Filling Incorporated
F,M Cello Corporation
F Cessco Incorporated
F Chase Products Company
F Chem Force America Incorporated
F,M Chem-Tech Incorporated
F Chem-Tech Limited
F Chemi-Coatings Incorporated
F Chemical Packaging Corporation
F Chemical Packaging Services Incorporated
F Chemical Products
F Chem-Pak Incorporated
F,M Chemscope Corporation
F Chemsico Incorporated
F Chemspray Incorporated
F,M Chesebrough-Pond's Incorporated
F,M Claire Manufacturing Company
Continued
3-5
-------
TABLE 3-1 (CONTINUED)
U.S. AEROSOL PRODUCT FILLERS8
F,M Clairol Incorporated
F J.L. Clark Company
F,M Cline-Buckner Incorporated
F,M Colgate-Palmolive Company
F Contact Industries Incorporated
F,M Cosmair Incorporated
F,M CRC Chemicals
F,M Creative Products Corporation
F,M Crown Industrial Products Company
F CSA Limited Incorporated
F Custom-Pak Products Incorporated
F,M Dana Parfums Corporation
F,M DAP Incorporated
F,M DeMert & Dougherty/Aeropak Division
F,M DeSoto Incorporated, Chemical Coatings Division
F,M Dow Brands
F,M Dupli Color/Sprayon Products Company Incorporated
F,M Dymon Incorporated
F Dynamatch
F E. Davis & Company
F,M Enterprise Sales Company
F Eveready Products Corporation
F Fasse Paint Company Incorporated
F,M Faultless Starch/Bon Ami Company
F Fluid Packaging Company Incorporated
F,M Follmer Development
F Forrest Paint Company
F Frank Orlandi Incorporated
F,M Fre-Kote Incorporated
F,M Fuller Brush Company
F,M Fulton Chemical Company
F,M Gabriel Manufacturing Company
F Guardsman Products
F G.C. Thorsen
F Gainor Manufacturer Company
F GEM Incorporated
F Gemini Lacquers
F,M General Paint
F,M Gillette Company
F,M Grow Group
F Holt Lloyd Corporation
F,M Huntington Laboratories
F,M Hydrosol Incorporated
F Hysan Corporation
F IKI Manufacturing Company Incorporated
Continued
3-6
-------
TABLE 3-1 (CONTINUED)
U. S. AEROSOL PRODUCT FILLERS8
F,M Illinois Bronze Paint Company
F Jerome Laboratories Incorporated
F JL Manufacturers
F J.M. Products
F,M Knight Oil Corporation
F Lighthouse for the Blind
F Marcy Laboratories Incorporated
F Major Paint, Aerosol Packaging Division
F,M Midco Products Incorporated
F Minnesota Mining and Manufacturing (3M)
F,M Mobile Paint
F,M Mohawk Finishing Products Incorporated
F,M Mohawk Laboratories Incorporated
F,M Morton Pharmaceuticals Incorporated
F,M National Aerosol Products
F,M New England Aerosol and Packaging Corporation
F,M Noxell Corporation
F Orb Industries Incorporated
F Pel Associates Incorporated
F,M Pennwalt Corporation
F,M Petro Chemical Products
F,M Percy Harms Corporation
F Peterson/Puritan Incorporated
F Pharmasol Corporation
F Piedmont Laboratories Incorporated
F,M Plasti-Kote Company
F,M Plaze Incorporated
F Precise Packaging
F Premier Dye
F Presto Foods
F,M Pyroil Company
F Quest Chemical
F,M Raabe Corporation
F,M Radiator Specialties Company
F Randolph Products Company
F Rawn Company Incorporated
F Regency Chemical
F Rempak Industries
F,M Rite Off Incorporated
F Riverside Metal Products Incorporated
F RSI Incorporated
F Rudd Paint & Varnish Company
F,M Rustoleum Corporation
F Safety Plus Incorporated
F,M S.C. Johnson & Son Incorporated
F,M Schering-Plough Incorporated
F,M Scott's Liquid Gold
Continued
3-7
-------
TABLE 3-1 (CONCLUDED)
U. S. AEROSOL PRODUCT FILLERS8
F Security Equipment Corporation
F,M Seymour of Sycamore Incorporated
F Shaefer Paint Company
F Shield Packaging Company
F Shield Packaging of California Incorporated
F,M Shirlo Incorporated
F,M Shulton Incorporated
F Southern Coatings & Chemical Company
F,M Speer Products Incorporated
F Spray Can Specialties Corporation
F,M Spray-on Products/Division of Sherwin-Williams
F Spray Products Corporation
F Standard Management Incorporated
F Stanhome Incorporated
F,M Star Chemical Company Incorporated
F,M Stoner Incorporated
F Strobel Products Company Incorporated
F Sun Laboratories Incorporated
F Sun Laboratories of Atlanta
F Sunrise Packaging
F,M TDP Industries Incorporated
F,M Tech Spray
F Technical Chemical Company
F Testor Corporation
F Tradco
F Ultramotive Corporation
F Unipak Incorporated
F Unsmoke International
F U.S. Aviex Company
F,M U.S. Packaging Corporation
F Valvoline
F Virbac
F Warner Enterprises Incorporated
F,M Whitmire Research Laboratories
F,M Zep Manufacturing Company
F Zoe Chemical Company
F Designates contract fillers. These companies fill aerosol containers for trade but do not market
their own products.
F,M Designates captive fillers. These companies fill and market their own products.
3-8
-------
3.2.2.1 Aerosol Filling Lines
The basic pieces of equipment that comprise the filling operation are can
cleaners, can coders, powder or liquid fillers, valve inserters and crimpers, propellant
gassers, and capping operations. The total cost of establishing a new filling line can
exceed $2 million. Two key considerations in filling line design are the type of
products to be filled and the anticipated annual production volume. Many fillers have
several lines, each one made as versatile as possible yet compatible with the others in
order to maximize product adaptability. The diversity of aerosol formulations and
packaging forms that must be handled by filling lines is illustrated by the wide array of
aerosol products on the market. Some examples of specialized filling lines are aerosol
pharmaceutical lines, aerosol food lines, paint and lacquer lines, compartmented can
lines, and lines for highly viscous products. Aerosol lines are usually categorized
according to speed ratings in terms of number of units filled per minute. They can be
classified as slow, moderate, high, or very high, with production rates ranging from 10 to
500 units per minute.
3.2.3 Formulators
Aerosol formulations for individual products are specified by the marketer.
Generally, the formulation is blended at the same facility where the can is filled (either a
captive or contract filler). In a few cases, usually involving proprietary formulations, the
formulation is blended at a separate facility and is shipped to the filler.
3.2.4 Propellant Suppliers
The types of aerosol propellants currently in use and the domestic companies that
supply them are presented hi Table 3-2. Currently, about 81 percent of U. S. aerosol
products are pressurized with HC propellants. Another 7 percent use CO?, and the
remaining 12 percent use N2O, CFC's, DME, N2, HFC-152a, and HCFC's (listed in
approximately descending order).4
3-9
-------
Hydrocarbon propellants are derived from petroleum raw materials generally
referred to as liquified petroleum gas (LPG). In the United States, about 70 percent of
the LPG produced is extracted from natural gas, and 30 percent is refined from crude oil.
The initial refining is carried out by large petrochemical companies. Aerosol propellant
companies further refine these materials to produce purified, aerosol-grade propane, n-
butane, and isobutane. Isobutane accounts for 70 to 75 percent of the HC's used in
aerosols. Propane accounts for 15 to 20 percent of the market share, and n-butane has
around a 10 to 15 percent share. In 1989, approximately 65 million gallons of LPG were
consumed to produce HC propellants used in approximately 3 billion aerosol units. This
amount accounts for about 0.2 percent of total annual U. S. LPG production.
Seven companies in the United States supply aerosol-grade HC's. Currently, 3
companies (Aeropres Corporation, Diversified CPC International, and Phillips 66
Company) produce over 80 percent of the HC propellants used in the United States. >
For some of these companies, the production of aerosol propellants comprises virtually
100 percent of their business (i.e., aerosol products are the only use for the propellants
they manufacture). For example, Aeropres Corporation is almost totally dependent on
the aerosol industry, because their primary activity is the production of aerosol
propellants. Although they market small quantities of highly purified gases for
instrument calibration purposes and some unpurified fuel gases, these markets represent
only a small fraction of Aeropres's overall business. For more diversified companies
such as Phillips 66 Company, the production of aerosol propellants may represent a much
smaller segment of their overall business.
3.2.5 Raw Material Vendors
Within the major categories of consumer aerosol products are thousands of
specific products with formulations containing a vast number of chemicals. Table 3-3
lists the major types of raw materials used to produce aerosol formulations. The various
raw materials are supplied by hundreds of different companies in the United States.
3-10
-------
TABLE 3-2
U. S. AEROSOL PROPELLANT SUPPLIERS5'11'12
Hydrocarbons
Aeropres Corporation1
Copia Associates Incorporated
Demert & Dougherty/Aeropak Division
Diversified Chemicals and Propellants*
Petrolane Transport
Phillips 66a
Technical Propellants
Carbon Dioxide
Liquid Carbonic Corporation
Nitrogen and Nitrous Oxide
Puritan-Bennett Corporation
Fluorocarbons
Aeropres Corporation
Copia Associates Incorporated
Diversified Chemicals and Propellants
DuPont
Atochem Corporation
Technical Propellants
Kaiser LaRoche
Allied Signal Incorporated
Dimethyl Ether
Aeropres Corporation
Copia Associates Incorporated
Diversified Chemicals and Propellants
DuPont
Technical Propellants
Hvdrofluorocarbons and Hydrochlorofluorocarbons
Allied Signal Incorporated
DuPont
ICI
These three companies account for over 80 percent of U. S. hydrocarbon propellant production.
3-11
-------
TABLE 3-3
RAW MATERIALS USED IN AEROSOL FORMULATIONS8
Alcohol
Antioxidants, Bacteriostats
Antiperspirant Raw Materials
Antistatics
Deodorants
Emollients
Emulsifiers
Gellants
Hair Spray Resins
Insect Repellents
Lanolin & Derivatives
Odor Neutralizers
Paint, Concentrates & Pigments
Perfuming Materials
Pesticide Materials-Toxicants & Synergists
Preservatives
Quaternary Ammonium Compounds
Silicones
Solvents
Stabilizers
Sunscreens
Surfactants
Vapor & Flame Suppressors
3-12
-------
3.2.6 Container Manufacturers
Approximately 25 container manufacturers supply tinplate, aluminum, glass, and
plastic cans for the aerosol industry. Table 3-4 presents a list of container manufacturers
in the United States. Although many of these companies also produce nonaerosol
containers or other products, some depend on the aerosol industry for most of their
O 1/1
business. ' When making a decision about what type of can to use for a specific
product, the marketer must consider the size of the can, whether the formulation may
react with the can, what the pressure rating of the can should be, the aesthetics of the
can, and product safety. The following sections provide brief discussions of the primary
types of aerosol containers and the part they play in the market.
3.2.6.1 Tinplate Cans
In the United States, the 3-piece tinplate aerosol can is the predominant
packaging medium for most aerosol products, with over 87 percent of all aerosol products
being packaged in tinplate cans. Tinplate cans are generally the least expensive of the
various types of aerosol cans. The cost varies with can size and pressure rating. An
average tinplate aerosol can costs about $0.25, although cans with higher pressure ratings
19
may cost up to about $0.85. Although tinplate cans are relatively versatile, they are
often not used with formulations of high water or saline content because of corrosion
problems. They also may not be desirable for products that require aesthetic appeal, such
as perfume.
Four companies (United States Can Company, American National Can Company,
Heekin Can Incorporated, and Crown Cork and Seal Company) produce over 95 percent
of the tinplate aerosol cans used in the United States today. •*'*" One of these
companies, United States Can Company, is very dependent on the aerosol industry.
While it also makes some nonaerosol paint cans, this company has over 70 percent of its
business dedicated to aerosol can sales. Conversely, the other 3 major aerosol can
suppliers are less dependent on the aerosol industry, because their principal products are
3-13
-------
TABLE 3-4
U. S. AEROSOL CONTAINER MANUFACTURERS5'8'13'14
Tinplate Containers
American National Can Company* Heekin Can Incorporateda
CMB Enterprises Incorporated Ring Can Company
Crown, Cork and Seal Company Incorporated4 Sexton Can Company
Davies Can Company Specialty Packaging Products, Inc.
Garrett-Hewitt International United States Can Company*
Jumbo Size Metal Containers
Advanced Monobloc Complete Cosmetic Service
CMB Enterprises Incorporated United States Can Company
Aluminum Containers
Advanced Monobloc Lako Associates Inc.
American National Can Company Lechner U.S.A
Anomatic Corporation 3M Company
Complete Cosmetic Service Parker-Hannifin Corporation
Connecticut Metal Peerless Tube Company*1
Emson Research Incorporated Riverside Metal Products
Lablabo/BLM Associates Specialty Packaging Products Inc.
Coated Glass Containers
3M Company Wheaton Aerosol Company
Uncoated Glass Containers
Garrett-Hewitt International TJ. Holmes Company
Riverside Metal Products Wheaton Glass Company
Plastic Containers
Wheaton Aerosol Company
Barrier Pack Containers
Advanced Monobloc Exxel Container L.P.
CMB Enterprises Incorporated Lechner U.S.A.
Confer United States Can Company
Crown Cork and Seal Company
a These 4 companies supply over 95 percent of the tinplate aerosol containers in the U. S.
These 2 companies supply over 80 percent of the aluminum aerosol containers in the U. S.
3-14
-------
food and beverage containers. An estimated 4,000 to 6,000 persons are directly
dependent on the tinplate aerosol can industry in the United States.
3.2.6.2 Aluminum Cans
Aluminum aerosol cans comprise about 12 percent of the aerosol container
market in the United States.1*' 1' Aluminum cans generally cost 15 to 30 percent more
to produce than equivalent tinplate cans because raw material and manufacturing costs are
higher for aluminum, even though approximately 30 percent of the aluminum cans are
made from recycled material. Because aluminum aerosol cans are produced by impact
extrusion, they have no welded side-seam (as used in the 3-piece tinplate can).
Accordingly, they appear smooth and sleek, and for that reason may be desirable for use
with some personal care products. Aluminum cans are also often used instead of tinplate
cans to contain formulations corrosive to tinplate (such as those high in water
content).13'14
Two companies (Peerless Tube Company and Advanced Monobloc) produce over
80 percent of the aluminum aerosol cans in the United States. These two companies are
almost totally dependent on the aerosol industry. While they both make other types of
aluminum tubes, these companies primarily produce aerosol cans.10,14,18 Aluminum
aerosol can production is a small percentage (less than 0.1 percent) of the overall
aluminum container market.
3.2.6.3 Glass Containers
The use of glass containers for formulated aerosol products began about 1950,
although one product, a topical anesthetic spray consisting of ethyl chloride, was
marketed about 1910. The glass aerosol market, which consists primarily of fragrance
products and Pharmaceuticals, grew steadily until the mid-1970's when the switch from
CFC's to HC propellants caused a sharp decline. As marketers became less reluctant to
utilize HC propellants in fragrance products, the market recovered to some degree over
3-15
-------
the years. Today, glass aerosols account for approximately 0.5 percent of the aerosol
container market. *•
3.2.6.4 Plastic Containers
Plastic aerosol containers currently account for a negligible share of the aerosol
market. Many types of plastic containers have been examined by the industry, but none
has proved favorable enough to capture a significant market share. Only one company
(Wheaton Plastics Company) currently produces plastic aerosol containers, and these
comprise a very small segment of Wheaton's business. The few plastic aerosol
containers manufactured are typically made of polyethylene terephthalate (PET).1^
3.2.7 Valve Suppliers
The valve is an essential element of every aerosol dispenser. When actuated, it
releases the product from the container and produces a spray pattern appropriate for the
specific application. In the United States, 9 firms supply virtually all aerosol valves.
Table 3-5 presents a list of these valve producers. Three companies (Precision Valve
Corporation, Seaquist Valve Company, and Summit Packaging Systems) supply over
90 percent of the aerosol valves used in the United States. Each of these companies,
while also involved to varying degrees in the production of pump spray valves, depends
on the production of aerosol valves for pressurized containers as a major portion of their
business.2^
Although some valve manufacturers list suggested specific valve combinations for
various standard aerosol products, the companies usually manufacture valves to the
marketers' specifications. One U. S. valve manufacturer reportedly has over 10,000
specific aerosol valve designs from which to choose.10 While many marketers have their
own unique ideas concerning what constitutes an acceptable spray pattern, a large degree
of supplier interchangeability can be obtained by maintaining the same orifices, gaskets,
3-16
-------
TABLE 3-5
U. S. AEROSOL VALVE MANUFACTURERS5'8'10
General Purpose Valves
Bespak Incorporated
Emson Research Incorporated
Newman-Green Incorporated
Precision Valve Corporation1
Seaquist Valve Company3
Summit Packaging Systems4
Valves for Use with Foam. Food, and Viscous Products
Bespak Incorporated
Clayton Corporation
Precision Valve Corporation
Risdon Corporation
Seaquist Valve Company
Summit Packaging Systems
Valves for Use with Paint Products
Newman-Green Incorporated
Precision Valve Corporation
Seaquist Valve Company
Summit Packaging Systems
Sprayon Products
Valves for Use with Glass/Plastic Bottles
Bespak Incorporated
Precision Valve Corporation
Risdon Corporation
Valves for Use with Carbon Dioxide Propellants
Bespak Incorporated
Newman-Green Incorporated
Precision Valve Corporation
Seaquist Valve Company
Summit Packaging Systems
Metered Valves
3M Company
Bespak Incorporated
Emson Research Incorporated
Risdon Corporation
Minnesota Mining and Manufacturing (3M)
These three companies produce over 90 percent of the aerosol valves used in the United States.
3-17
-------
and other attributes during the development of alternative or secondary source valve
specifications. *•
Research conducted by valve manufacturers includes development of new valves
that reduce flammability and provide better spray characteristics. Innovations in valve
design have also allowed greater use of CO2-propelled products, thereby reducing the use
of CFC and HC propellants.
3.2.8 Cover Cap Manufacturers
Aerosol cover caps are necessary to protect the spray head from damage, prevent
the actuator from discharging the contents during storage, prevent accumulation of dust or
dirt on the valve, and enhance the general appearance of the container. Table 3-6 lists
the 11 cover cap manufacturers in the United States. Two of these companies (Berry
Plastics and Knight Plastics) produce over 90 percent of the aerosol caps used in the
United States.10
3.3 REFERENCES
1. Johnsen, M., The Aerosol Handbook, 2nd Edition. Wayne Dorland
Company, Mendham, New Jersey, 1982.
2. Meeting Summary, National Aerosol Association (NAA) Participation in
EPA Study on Volatile Organic Compounds (VOC's) in Consumer Aerosol
Products. U. S. Environmental Protection Agency, Research Triangle
Park, NC. July 2, 1990.
3. J-^tter from H. McCain, Aeropres Corporation, to B. Teague, U.S.
Environmental Protection Agency, May 9, 1990 (Includes a 1989 Update
of Information Contained in: Brock, G., Hydrocarbons - A Viable
Alternative Aerosol Propellant. 1977).
4. Radian Corporation. Aerosol Industry Success in Reducing CFC Propellant
Usage. Prepared for U.S. EPA, Air and Energy Engineering Research
Laboratory, EPA-600/2-89-062. November 1989.
3-18
-------
TABLE 3-6
AEROSOL CONTAINER COVER CAP MANUFACTURERS1'6'19
Anomatic Corporation
Berry Plastics a
Clayton Corporation
Knight Plastics a
Pacific States Plastics
Paragon Plastics Incorporated
Precision Valve Corporation
Risdon Corporation
Shellvick Industries Incorporated
Trans Container Corporation
West Perm Manufacturing & Supply
These 2 companies produce over 90 percent of the cover caps used in the U. S.
3-19
-------
5. Chemical Specialties Manufacturers Association. Aerosol Pressurized
Products Survey - United States 1989.
6. Conversation between B. Moore, U.S. EPA, and D. Minogue, Precision
Valve Corporation, October 23, 1991.
7. U. S. Environmental Protection Agency. Symposium on Regulatory
Approaches for Reducing VOC Emissions from the Use of Consumer
Products. Office of Air Quality Planning and Standards, Research
Triangle Park, NC, EPA-450/3-90-008. January 1990.
8. 1989-1990 Buyer's Guide. Aerosol Age. Vol. 34, No. 10. October 1989.
9. Radian Corporation. Control Technology Overview Report: Volatile
Organic and Chlorqfluorocarbon Use in Aerosol Products. Prepared for
U.S. Environmental Protection Agency, Air and Energy Engineering
Research Laboratory. EPA Contract No. 68-02-4286. 1989.
10. Teleconference between B. Broberg, Radian Corporation, and M. Johnsen,
Montford Johnsen Associates. September 10, 1990.
11. Teleconference between L. Davis, Radian Corporation, and H. McCain,
Aeropres Corporation. September 11, 1990.
12. Draft Trip Report - Site Visit: Claire Manufacturing Company. Submitted
to EPA by B. Broberg, Radian Corporation. July 24, 1990.
13. Teleconference between L. Davis, Radian Corporation, and T. Maloney,
American National Can Company. September 11, 1990.
14. Teleconference between L. Davis, Radian Corporation, and R. Jacobsen,
U. S. Can Company, September 13, 1990.
15. Daly, J.J., "Emerging New Propellant Blends." Aerosol Age, October
1986.
16. Dunn, D.P., "New Propellants Respond to Regulatory Developments."
Aerosol Age, January 1988.
17. Sterling, J.D., "Fluorocarbon and Dimethyl Ether Aerosol Propellants"
Aerosol Age, December 1982.
18. Teleconference between L. Davis, Radian Corporation, and D. Drake,
Advanced Monobloc. September 10, 1990.
3-20
-------
19. Teleconference between L. Davis, Radian Corporation, and W. Hoyle,
Wheaton Plastics, Inc. Sept. 10, 1990.
20. Teleconference between L. Davis, Radian Corporation, and A. Welch,
Precision Valve Company, September 14, 1990.
3-21
-------
SECTION 4.0
ALTERNATIVE DISPENSING TECHNOLOGIES
4.1 INTRODUCTION
One option that has been suggested as a means of reducing VOC emissions from
aerosol consumer products is to switch from conventional aerosol packaging systems to
alternative technologies that reduce the amount of HC propellant required to expel the
product. While this is a reasonable and effective approach for many applications, each
individual conversion must be considered carefully with regard to the net environmental
benefit that will be achieved. This section describes the advantages and limitations of
several alternative packaging technologies that have been or may be used for consumer
products.
4.2 THE "BAG-IN-CAN" SYSTEM
One alternative dispensing system for aerosol products is the bag-in-can system.
This container (aluminum or tinplate) houses an inner bag containing the product
concentrate and the exo-space propellant. The bag can be made of one of several
different materials to ensure that the product and the propellant are kept separate. Under
normal use, the system is designed to permit gas-free dispensing; however, upon
disposal, the propellant would likely be released to the environment. The top of the can
is fitted with a valve and an actuator. As the actuator is depressed, the inner bag begins
to collapse due to the pressure of the exo-space propellant, and the product is dispensed.
®
Figure 4-1 shows the Sepro Can , which was the first bag-in-can unit introduced for
aerosol products.
The bag-in-can technology can be used to dispense viscous products with a
positive yield point, i.e., the product retains its shape. The primary use is for post-
foaming, gel-type shave creams (although these are now marketed in piston cans). Other
4-1
-------
The S«(iro oat a dejigiwa
10 co i la B" m * ipucitic
w«v «ai.n nmt tnt valve
11 op«n«o. Thti action
m»iimii« product u*a«n
betttr man anv oiner
aerosol ran.
Figure 4-1 The Sepro Can
®
4-2
-------
products include toothpaste, depilatories, caulking compounds, catsup, mustard, insulating
gel, honey, jelly, vegetable oils, artist's pigments, petrolatum, cake icing, cleaners,
disinfectants, medicines, dental gels, gum cements, and hair coloring pastes. Some bag-
in-can systems have been used as the power units for nail dispensers.
There are many limitations to this type of packaging system, some of which are
listed below:
• Products with high viscosities - result in slow transport through valve
• Products that are highly lubricating - result in a loss of seal for rubber
components
• Products that are acidic - tend to attack certain types of bag materials
• Products with long shelf lives before use - the propellant permeates the bag
and enters the product
• Products containing strong solvents - result in bag degradation or
dissolution
• Products that must be hot-filled - results in flammability hazard and/or bag
distortion
Most bag-in-can systems use HC propellants such as n-butane, isobutane, propane,
and their blends. The use of compressed gases is severely limited because there is no
reserve against slow leakage, and the propellant may be unable to dispense the entire
contents of the can. It should be noted that the Alucompack and Micro-Compack systems
can use compressed gases because the exo-space is greater than that of the inner tube or
bag. Therefore, the pressure will not decrease substantially during tube collapse. The
HC-propelled bag-in-can requires a propellant content of about 0.5 percent by weight.
The post-foaming gel-type shave creams contain approximately 2 percent by weight
VOC's in the product to cause the gel to foam when the product comes in contact with
the skin. This can be compared with 3 percent VOC content that is typical of regular
4-3
-------
H
en
en
i
en
en
5
§
U
6
M
.1
00
•c
1
00
a
09
^
|
S
00
E
UH
1
i
to
co
§
c
DO
n
Horizontal "V"
shaped pleats
o
Conalloy plai
Nylon
Lamicon
00
*«
CO
OS
00
09
i
8 E
U o
, <^* ^J
« 0
cca
° o £j
.S *cn
s '> <«
asp
®c
U
2
Q.
C^
€ a
Fits can body w
longitudinal bul
§
oo
_c
en
CS
00
u
03
09
T3
-J
00
'eb
CO
^
,2
09
S
u
§
u
S
u
*j o
C3 n-t
1|
Aluminum
a. I
V J
i?
D £
•
-------
aerosol shaving creams. Hair sprays, which typically uses 20 to 35 percent HC propellant,
require only about 2 percent propellant if packaged in a Sepro Can . However, the spray
characteristics of the hair spray deteriorates, and the total quantity of VOC's emitted may
actually increase due to increased solvent requirements.
Several different versions of the bag-in-can dispenser are currently used in the
marketplace. Table 4-1 lists the various suppliers of these systems as well as the various bag
types and filling methods. The Sepro Can dispenses between 94 and 97 percent of the
product. Most of the other systems dispense closer to 98 percent of the product.
4.3 PISTON CANS
A second type of alternative aerosol dispensing system is the piston can. This unit
consists of an aluminum or tinplate can and a free-floating polyethylene piston that separates
the propellant from the formulation. Figure 4-2 presents a cross section of a piston can.
The propellant is injected through the base of the can below the piston. Hydrocarbons are
the most common propellant type for the piston cans. Compressed gases cannot be used
because they do not maintain a constant pressure as the contents are expelled.
These systems can be used for creams, gels, pastes, lotions, and other low to medium
viscosity products such as shave creams, chocolate syrups, margarine, air fresheners,
cheeses, cake toppings, and silicone-based tub and tile sealants. Piston cans typically
dispense 95 to 98 percent of their contents. Limitations of piston cans include:
• Products with low viscosity will distort the piston
• Piston bypass and permeation will result in propellant reduction and foam
generation in the product
• Incompatibility of the product with the can or piston
4-5
-------
, SPOUT
^-ACTUATOR
SAFETY CAP
PRODUCT
GAS
GAS PLUG
-VALVE
•ALUMINUM
CAN BODY
—•POLYETHYLENE
PISTON
xDOUBLE-SEAMED
ALUMINUM CAN END
<8
Figure 4-2 American National Can Company's Mira-Flo Piston Can
4-6
-------
Suppliers of piston can dispensing systems include American National Can Company,
Advanced Monobloc, Ltd., United States Can Company, Boxal/Alusuisse, and Rocep
Pressure Packs, Ltd. Most of the units marketed by these companies are standard piston
systems, except for the Rocep® cans and the Boxal* pump dispenser. The principal
difference in the Rocep® can is that it uses a double piston to prevent contamination of the
product by the propellant. It should be noted that currently the Rocep® can employs an
HCFC propellant primarily because Rocep does not possess a suitable facility for the safe
handling of flammable gases. The Boxal® pump dispenser is a propellantless version of the
piston can that operates on a vacuum suction principle. This unit consists of an aluminum
can with an inner piston, perforated bottom, and an actuating spout that meters product flow.
Depression of the actuator creates a low vacuum and causes the piston to move upwards,
causing expulsion of the product. This package dispenses approximately 95 to 97 percent of
the material.
Piston cans are similar to the bag-in-can systems in that only a small amount of
propellant is needed to dispense the contents. Typically, the piston can requires about
0.5 percent propellant. This can be compared to 3 percent used with traditional viscous
aerosol products.
4.4 ENVIRO-SPRAY® SYSTEM
The Enviro-Spray® system is the opposite of the bag-in-can system in that the product
occupies the exo-space, and the propellant is inside the bag. The propellant bag consists of a
large pouch containing a 50-percent citric acid solution in water, and four smaller pouches
containing sodium bicarbonate. The smaller pouches are ruptured as the contents are
expelled and thebag expands, pressurizing the container. Mixing of the citric acid and
sodium bicarbonate produces sodium citrate salts and CO2 gas that maintains the pressure in
4-7
-------
&
B.
Ed
.o
***
2
£
o
*-
js
on
.2
I
4
2!
oo
-------
the unit at the original level. The product can be dispensed as acoarse spray, gel, paste, or
post-foaming gel. The citric acid pouches in this unit are laminates that have a core layer of
aluminum or polyester. The reservoir of sodium bicarbonate for the first pressurization step
is contained in a special water-soluble polyvinyl alcohol bag. This system does not require
any VOC propellants. Figure 4-3 shows the various stages in the operation of an Enviro-
Spray dispensing system.
Enviro-Spray dispensers are used for various insecticides, leaf shines, shave creams,
colognes, rubefacient creams, catsup, mustard, and plant nutrient sprays. This dispensing
system is currently marketed in the United States and Europe by ECOM (a division of CCL
Industries, Ltd.) Toronto, Canada. Some limitations of this dispensing system include:
• Product incompatibility with the can
• Product incompatibility/permeation of the pouch
• Variations in delivery rate due to pressure fluctuations
4.5 PUMP SPRAYS
There are two basic types of pump dispensers, the aspirator type and the standard
mechanical type. The aspirator type consists of a jar containing a dip tube, which aspirates
the product into an orifice and out of the dispenser as a spray. Aspirator pumps have been
used primarily for space spray insecticides; however, smaller versions of this type have been
used for perfumes and colognes. The primary limitation of these units is that the product
must have low viscosity so that it can be dispensed as a spray.
Several aspirator-type sprayers are currently available. The "Pre-Val" unit (made by
Precision Valve Corporation) consists of a glass or plastic jar (product reservoir) and a dip
tube extending through a bag holding liquid propellant. When the valve button is depressed,
propellant is discharged, creating a vacuum that causes the concentrate to be
4-9
-------
TABLE 4-2
PUMP SPRAYER SYSTEMS AND SUPPLIERS
Product
Type
Supplier
Pre-Val Unit
Aspirator
Precision Valve Corporation
FLIT" Gun
Aspirator
Penola Oil & Chemical Corp.
Esso Oil Company
Humble Oil & Refining Co.
Exxon, Inc.
Finger-Pump
Sprayer
(Standard)
Finger-pump
Calmar Corporation
Bakan Products Co.
Risdon Manufacturing Co.
Emson Research Company
Seaquist Closures,
Division of Pittway, Inc.
Kingswood Laboratories, Inc.
United Industries Corporation
Trigger
Sprayer
(Standard)
Trigger-pump
Afa Corporation
4-10
-------
entrained and discharged. Because the propellant does not reside in the same container as
the formulation, any liquid propellant can be used. A compressed gas cannot be used
because the entire contents of the propellant container would be discharged soon after the
valve is opened (unless a gas cylinder with very high pressures is used).
The aspirator-type pump sprayer consists of a cylinder and piston arrangement connected
to a reservoir from which the product is aspirated through the dip tube, through a jet orifice,
and propelled by a stream of air. An example of this type dispenser is the old "FLIT" gun.
These have been used mainly for insecticides and were sold by companies such as Exxon and
Gulf. Today, only a very limited number of these units are sold. These units do not use any
kind of propellant.
The standard-type pump sprayers commonly in use today exist in two forms, the finger-
pump sprayer and the trigger-action sprayer. The operating principles of the two systems are
the same. The actuator/valve assembly usually has a threaded connection that fits into a
glass or plastic container. As the actuator is depressed, the valve stem is forced downward
into the body chamber that is normally filled with product. The product forces the chamber
to expand outward, allowing product to flow past the piston into the orifices of the stem.
The liquid then moves up the stem, through the adapter and button, and out the actuator as a
stream or spray. When the button is released a partial vacuum is'created in the chamber
allowing product to refill the body chamber. The principal differences between the finger-
and trigger-pump sprayers are the amount of product dispensed per actuation and the
mechanical advantage of the pinioned trigger that provides higher internal pressure in the
chamber.
The standard pump sprayers are best suited for surface applications and are used to
dispense hair sprays and moisturizers, residual insecticides, herbicides, pet sprays, colognes
and perfumes, curl activators, lens cleaners, spot cleaners, window cleaners, cookware
lubricants, topical sprays, chrome polishes, stainless steel cleaners, and etc. Pump sprayers
can be modified into extruders by replacing the actuator with a spout. These extruder
4-11
-------
systems can be used to dispense Pharmaceuticals, skin dewrinklers, perfumed lotions,
dishwashing detergents, fabric softeners, and other lotions and gels. The valves in these
pump systems make them sensitive to a number of product types, including:
• Volatile flammables
• Viscous liquids - results in coarse spray or stream
• Strong solvents
• Sterile liquids - sterility is lost at first actuation
• Acidic liquids - acetal valve components dissolve at low pH
• Moisture-sensitive liquids - moisture enters by return air and permeation
• Suspensoid fluids - results in valve plugging
• Foam-type emulsions
• Polyethylene-warping liquids;
• Staining liquids - because of dribble;
• Air- or light-sensitive liquids;
• Two-phase liquids - phases can separate in the valve chamber and be resistant to
reconstitution by shaking;
• High-odor liquids - permeates plastic bottles; and
• Thixotropic viscous products.
Despite all these limitations, finger-pump sprayers are the major competitor to aerosols in
certain product categories. Table 4-2 lists the types and suppliers of the various pump
sprayer dispensing systems.
4.6 DISPENSING CLOSURES (SQUEEZE BOTTLES)
Another aerosol alternative is the screw-threaded closure or cap with a dispensing hole
which is plugged shut by various cap features when the product is not in use. Three of these
designs are shown in Figure 4-4. A metal can or flexible plastic container is
4-12
-------
SWOM
OfOI OAMIC*
U»T TA«
SRAP TOP
STRAP
lOWf • MIMOI
SKMT
ACTUATOM
PINGtM SECTION
DECK
BODY TUiE
OMIPICI
•OOV
•OOVTU1E
ACTUATOB
DECK
800Y
TOGGLE
CAP
Figure 4-4 Dispensing Closures Made by Seaquist Closures Division
4-13
-------
inverted and squeezed to dispense the product. This type dispenser is very efficient, because
only the amount of product that adheres to the inside walls of the container will not be
dispensed. These units are used for liquids, thin gels, soft creams, and lotions. Some
examples are charcoal lighters, cosmetics, toiletries, other personal care products, paint
thinners and strippers, furniture polishes, margarine, catsup, mustard, lubricants, carburetor
and choke cleaners, silicone shoe and boot dressings, etc. The primary limitation is that the
product dispensed in these units must be able to flow freely. Consequently, many of these
products may require addition of solvent in order to achieve acceptable performance.
4.7 TWIST-N-MIST H®
The Twist-N-Mist IH (shown in Figure 4-5) is a pressurized packaging system that
dispenses the product using energy supplied by manually rotating the full-diameter screwcap
and integral piston. This is a propellantless dispenser. Accordingly, the only VOC's will be
those associated with the product itself. By twisting the threaded cap several revolutions, the
piston is raised, creating a vacuum in the reservoir below. This causes the product to rise
through the dip tube, past the stainless steel ball check valve, and into the cavity. The cap is
then twisted an equal number of turns in the opposite direction, moving the piston
downward, pressurizing the reservoir, and forcing the product into a Buna-N rubber bladder.
The "memory" of the elastomer causes the bladder to return to its original shape as the
product is dispensed through an aerosol-type valve. This unit dispenses about 95 percent of
the product.
This system is currently used for some hair spray products, and the supplier recommends
that it be used for personal care, household, industrial, and automotive products. The Twist-
N-Mist was developed and patented by CIDCO Group, Inc. Molds for the hair spray
products were produced by Avedon Engineering.
4-14
-------
Figure 4-5 Twist-N-Mist II"" by CIDCO Group, Inc.
4-15
-------
Currently existing drawbacks and limitations of this system include:
• Persistent stress cracking problem
• Inconvenience in that it can require many turns to expel the product
• Products cannot include foams
• Products cannot contain solvents incompatible with the Buna-N bladder
• Product incompatibility with the bladder results in product discoloration or odors.
4.8 THE EXXEL® SYSTEM
Another alternative dispenser is the Exxel system by Exxel Company, which consists of
a thick, elastomeric rubber sleeve whose open end is fitted with a valve and atctuator. The
product is compressed into an inner PET sleeve and, because of the elasticity of the outer
sleeve, is under pressure. Products currently dispensed in the Exxel unit include welding
®
flux spray, sun oil spray, muscle relaxant, sterile food products, Betadine topical antiseptic
solution, fragrances, hair gel, shampoo and conditioner, and hand and body cream. Skin
care, hair care, and pharmaceutical products of the post-foaming gel type are in the
developmental stages.
types and/or conditions:
developmental stages. The limitations of the Exxel® system include the following product
Solvents such as terpenes and ketones
Products with pH values over 10.0
Products containing more than 5 percent isopropanol
Products containing more than 60 percent ethanol
Prolonged exposures to temperatures over 113°F
High surface tension products
Resins capable of drying and clogging actuators
Products that require in-package mixing
4-16
-------
These product incompatibilities come into play when the product contacts various parts of
the unit, including the PET bottle, Nylon 66 valve housing, natural polypropylene/high
density polyethylene (HDPE) button, and 302-SS or 316-SS spring. 7^5 system also
experiences loss of pressure due to loss of elasticity of the sleeve. The pressure loss is
smaller for the smaller units (4 fluid ounces) that dispense 92 to 95 percent of the product.
The larger units (1 fluid ounces) dispense 92 to 94.7 percent of the product. However, these
ranges may be reduced to 90 to 93 percent for viscous products with positive yield points.
4.9 THE MISTLON ECOLOGICAL® SYSTEM
The Mistlon Eco-Logical® Spray Bottle is a propellantless system in which the product is
poured into a bottle fitted with a screw-threaded closure with an aerosol valve and actuator
and a polypropylene cap. The base section of the unit contains a hollow cylinder with a one-
way compound valve, which functions as a piston within a cylinder protruding into the
container, also ending in a one-way valve. To pressurize the air in the container, the base
section is pumped a number of times. The maximum pressure achieved is about 100 psig.
By pressing a soft diaphragm in the center of the base, excess air pressure within the hollow
cylinder is removed. The spray is very coarse. However, the unit can be equipped with a
MBU unit to produce a more acceptable spray.
The Mistlon Eco-Logical® system cannot be used for all products. It should not be used
for highly flammable formulations or formulations that deform polypropylene or attack
polyvinyl acetate. Additionally, its applications are limited in that it cannot be used for
direct foam products or highly viscous fluids. This unit is supplied by the MONDEX Trade
& Development Corporation in Toronto, Canada.
4-17
-------
4.10 AIRSPRAY® SYSTEM
This propellantless system is similar to the Mistlon Eco-Logical® system in that it uses a
pumping action to compress air into a pressure-resistant container. This unit is distributed
with a refillable screw top or with a disposable crimp-on. The containers can be made of
plastic, metal, or glass. When pressurized to the maximum pressure of 55 psig, this unit
will dispense up to 100 ml of product before it requires repumping.
The limitations of the Airspray system are similar to those of the Mistlon
Eco-Logical system. It is not compatible with highly flammable formulations and
formulations that deform polypropylene or attack polyvinyl acetate. It should not be used for
products that are highly viscous or are direct foams. This unit is marketed by the American
National Can Company and Airspray International, Inc. in the United States and by W.
Braun & Company in Canada.
4.11 THE SELV AC® SYSTEM
The Selvac system is a self-pressurized dispensing system. It consists of an aerosol
valve, an inner membrane made of butyl rubber to hold the product, and an outer energy
storage structure. The outer structure expands when the unit is filled under pressure with the
product. When the actuator is depressed, the outer energy structure exerts pressure on the
inner membrane and causes the product to be dispensed through the actuator. This system
can be used for liquids, pastes, gels, lotions, and creams. Typical products include bath
gels, body lotions, deodorants, hair products, shampoo, toothpastes, air fresheners,
disinfectants, insect sprays, plant sprays, stain removers, antiseptic sprays, nasal sprays,
dental products, topical creams, and flea and tick sprays. The Selvac® system is marketed
by the Selvac Corporation.
4-18
-------
4.12 THE WEEDING NATURE SPRAY® SYSTEM
The Werding system consists of various actuators and nozzles, depending on the product
to be dispensed. The Werding 'R' Actuator can be designed to provide a constant delivery
rate, regardless of the internal pressure of the unit, thereby making it most useful for
products pressurized with compressed gases. The thrust regulator controls flow into the
nozzle, where the multistaged, interconnected venturi system results in a higher mechanical
breakup effect than conventional actuators. The system also includes two stainless steel
accelerator discs, a plastic expansion chamber, and a regulation disc. The design of the
regulation disc and the nozzle are responsible for the regulation of the product flow. Under
high pressures, the metal disc compresses, and the orifice size increases. This causes an
increase in turbulence and a resistance to product flow through the thrust regulator. This
ability to accommodate pressure fluctuations results in a constant dispensing rate of the
product.
4.13 VAPORIZERS
Vaporizers provide mists or condensation nuclei of the product in the air. Electrically
operated vaporizers consist of a wafer containing the concentrate and a small heater that is
connected to an electrical wall outlet. As the wafer is warmed, the product is vaporized and
released into the air. These units are used primarily for insecticides and air fresheners and
are limited to products with appreciable vapor pressures. The wafers are marketed by S. C.
Johnson & Son, Inc.; Refinacoes de Milho, Brasil, Ltd.; Bayer, GmbH; and Reckett &
Coleman, Ltd.
4.14 STICK AND ROLL-ON APPLICATORS
The stick-in-canister units consist of an outer canister of polyethylene and polypropylene,
with a bottom-entering plastic screw that is used to elevate the product in solid form. Roll-
on applicators are comprised of a container, a ball, and a screw-on cap. When the cap is in
4-19
-------
place, the ball fits against a ring seal and depresses a perforated diaphragm beneath it. When
the cap is removed, the diaphragm is released, lifting the ball from the sealing ring, and
allowing the ball to turn freely. Product is dispensed when the ball is rolled against the skin.
These products include antiperspirants and deodorants, insect repellents, spot cleaners,
and analgesics. Sticks and roll-ons are very popular in certain product categories. For
instance, in the underarm products area, sticks and roll-ons command a market share of
approximately 74 percent, whereas aerosols account for only 23 percent.
4.15 ADDITIONAL CONSIDERATIONS OF DELIVERY SYSTEM SELECTION
This chapter has presented a number of alternative dispensing technologies that could
potentially reduce VOC emissions by reducing propellant usage. However, it must be noted
that the removal of propellant, which functions as a co-solvent in many products, may
require the addition of other solvents to dilute the product concentrate. This may offset any
VOC emission reductions achieved through the removal of the propellant. Therefore, each
product type must be evaluated to determine whether one or more of these alternative
technologies would be suitable for that specific application.
Another factor that needs to be considered when determining the feasibility of various
alternative technologies is the potential for emissions or other waste problems from the
manufacture or disposal of the containers themselves. Table 4-3 shows the types of materials
associated with each system. Materials such as glass and metal are easily recyclable, which
reduces the amount of waste generated. Other products such as butyl rubber and plastics are
more difficult to recycle. These issues should be considered when evaluating the suitability
of the alternative technologies.
4-20
-------
•4
s
H
C/3
w
H
C/2
t/3
05
*jr
RNATIVE DISP]
W
H
H-
Q
W
Cfl
3
<3
I-H
^
MATE]
Other
omponents
U
5 '§
Co *-*
U|
ll
!> "^
60
c
•a E
c
W
e
0
5.S
43 «
u 5
ss
43 J3
cx "3)
S3 .5
42 3
u £
__ o
5 '5
^ 43
S S
PS
o -o
S 4J C/3
•^.1^
2^°
CX «J M
^^•ij
fifig
c«
U -°
I §g
|| s
fell
S2g
u
42
">>
£
«
^,
"o
OH
cx
E
W)
1
<5
_
H
(ft
O
0
be
'i/j
-------
^
«
(CONCLU1
3
^
f^
^*
S
«
03
^
W3
O
S
02
1
PH
W2
KH
o
•4
w
H
«
«<
s
s
w
g«
D
^
>J
•<
I.H
Qi
^•^
Lu
(XI
H^
c
g
l|
6 1
u
*c3
i'S
03 -w>
°s
"c3
g -c
^ «
^ 3
>S
60
•1 s
c u
ci£
.i*^
Q
1
s
o
**"J
w-
nS rtl
QJ QJ
•S &
O QJ
3 .
1 1
S a ! 3 gl & 'S 3 a
g 5s|p?l 1 £|S
60
'C 2
ex g
eo 4«
Si ^^* MA
=« ex ^
1 ils'l -I
on >>;o Q vj JS
on Z PH S on CU
@g
a -2
® tn
p— i ^
® on*
*-> e VJ
fa C -
•^5 CU *•
5 •» o „
^J en -. @
*r £? wa ?^
5? ^ a g
tn 13 ^ &
•r x D 2
£ x .fi -s
H (3 P <
I
X)
(U
>.
^4-^
m
CD
g
O
c«
13
C/2
1 I
60 V3
S >,
•g e
m
03
g
O
fc S
Cu 3
fi^
c £
£ ^
^ S-
•s s
-------
I
P
U
>
1
w
E
!
^^
g
H
O3
03
O
Q
03
P*
O3
Q
H
§
C^
H
<
*t
T
Ed
P5
<
H
u
tfl
£
CO
•o g
a.
06 U)
OJ
< 3C
nimal
oducts
< u
o.
— U)
C u
O 3
« -D
CU L.
Q. Q.
2 «
louseho
Product
4~i {/)
0 >
C1J CD
C Q
w c>
• - g
"° 2
» "o
C/)
e
CU
4^
«
X
to
X
Deliver
XXXXXX X^-XXX X X
XXXXXX X X
e*- €»• e^. c^- x X x x x <>• p- x
XXX P" X C*. p"
XXXXXX XXXXX X X
XXX C*- XX XXC^'XX X XX
XXX P"P~XX X XX
* O"NQ Q OO OO*-*Q Q O Q Q*
O O"OZ Z OO ZC^*OZ Z Z Z ZO
O O CU OO O CU O
O->4-' «.«. -4-* O
»OO OO OO
O O 41 OO OIU O
o in ~> o o t\i — . o
o-o -- -o o
-Kit- oo rot-
cv Q. O O «- Q. O
in ^ o oo ^ «-
ro
A
•X « >•
2 E en © co
» 1 i ®- S "
5 x aSZ®" §
c, c'^Q-S wSc •*-•
€> >5[-£3 O) •— 4J o _ (0 w
c ^aso. c z « — © z,, t-
(D °- t/5 Q. >*- i X . ©CJ
u__ i c_ Mzcn^ai O)«r»4
©© Ot-OJ Ci ..— t_ CE"-W
O CL — ' t. (IJO) (U-M— *Z Q- ••— (U I- -^
l_ 4) (TJ '^- Ol Dl Q. U5 (U UJ "O-MOO
Q.UX > C'-- W)-»- X OJ L. i-tf) Q..^-
Q> OO C •— (- —X XJZ-— (UXflJ^-1
C/) CK CD UJ U. t— Q ^ UJ H* < 3(.0>(/)
1
u
0)
Q.
X
CU
V)
01
ra
CA
C
CJ C
Ul 0
ra •—
cu ^
U — ' U
T3 CD -;
0,^8:
— - (0 (0
o "^
Considerat
No data a\
Potential
a
* z r--
-------
In general, most alternative dispensing technologies currently do not enjoy a large
market share. This is primarily because of high cost, lack of consumer acceptance, or
narrow product applications. Without changing consumer market demands, these
technologies are likely to continue to represent only a small portion of the consumer product
9
industry. Table 4-4 lists the various alternative technologies, identifies the product share
for each, and indicates which consumer products could reasonably utilize the technology.
4.16 REFERENCES
1. Radian Corporation. Report to Congress - Volatile Organic Compound
Emissions from Consumer and Commercial Products - Underarm Deodorants
and Antiperspirants. Draft Report, December 1991.
2. Meeting of the National Aerosol Association and U. S. Environmental
Protection Agency, Office of Air Quality Planning and Standards. Durham,
North Carolina. May 7, 1991.
4-24
-------
SECTION 5.0
CHARACTERISTICS OF SELECTED AEROSOL PRODUCTS
5.1 INTRODUCTION
Many different consumer products are dispensed via aerosol delivery systems.
Each product is packaged in an aerosol form for a specific reason. This chapter
summarizes the attributes of the aerosol packaging form for selected consumer products.
The feasibility of using alternative dispensing technologies and non-HC propellants is also
discussed.
5.2 PERSONAL CARE PRODUCTS
5.2.1 Hair Sprays
Aerosol hair spray formulations are single-phase (the propellant is in solution with
the product). The solvent content (typically ethanol) of hair sprays is 60 to 70 percent.
The ethanol is used to solubilize the film-former resin and allows the spray to dry
rapidly.
Hair sprays are available in mechanical pumps and in other propellantless
containers such as the Exxel container. Only one comparison has been made of the
effect on emissions of switching from aerosol hair sprays to mechanical pumps or Exxel
containers (a California Air Resources Board [CARB] report by American Research and
Testing).* For adult users, more emissions resulted from aerosol products than for the
mechanical pumps. However, this was not true of teenage users. Teenagers using the
pump sprays tended to use more product per application, resulting in more emissions than
the aerosol package. The mechanical pumps are also less popular because of wet spray,
finger fatigue during use, and occasional plugging of the meter spray valve. Hair sprays
have been converted to water-based formulations using DME, thus decreasing the amount
5-1
-------
of ethanol required. In general, compressed gases cannot be used because the propellant
also serves as a solvent in the product.
5.2.2 Shaving Creams
Aerosols are the packaging of choice for shaving cream. Aerosol products make
up about 90 percent of the shaving cream market. These products are valued for their
performance. Simply pushing a button generates a foam lather that improves the razor
shave and reduces the number of nicks and cuts. The newer gels also use a HC
propellant, but the propellant is injected under a piston in the container and does not
come in contact with the product. Shaving creams are water-based formulations;
therefore the VOC content of the product is very low. Dimethyl ether is not used as a
propellant because it does not produce a foam.
Alternatives include tubes and mugs. These products are mixed with water and
applied to the skin with a brush. These products require more preparation than the
aerosol products. Compressed gases are not used because they produce a very satiny
foam that has not proven to be marketable.
5.2.3 Underarm Antiperspirants
Aerosol antiperspirants are popular with consumers because they produce a dry
spray and household members can hygienically share the dispenser. The a.erosol
antiperspirant accounts for approximately 18 percent of the underarm product market
share.
Antiperspirants are also available in semisolid stick, liquid roll-ons. and saturated
pads. All of these alternative forms have lower VOC contents than the aerosol form.
Compressed gases cannot be used in these products because the HC propellants are
5-2
-------
critical to the distribution of the product on the skin surface. If compressed gases were
used, the formulas would drip and run down the body.
5.2.4 Underarm Deodorants
Aerosol deodorants are popular with the consumer because the spray has a dry
feel and the user can share the dispenser with other household members. Aerosol
deodorants account for approximately 4 percent of all underarm products. Deodorants
are also available in both semisolid stick and liquid roll-ons. Both of these products have
fewer VOC's than the aerosol alternative. Compressed gases cannot be used for this
product for the same reasons identified for underarm antiperspirant. Some products are
available as water-based formulations that use DME as a propellant.
5.2.5 Medicinal Products
This category consists of a wide variety of products and makes up only
1.1 percent of the aerosol market. Examples of pharmaceutical products include metered
dose inhalants, such as steroids and adrenergic bronchodilators, hair restorers, skin
chillers, and medical solvents. Because of the variety of products, it is difficult to make
general statements about why these products are packaged in aerosol sprays. Some
medicinal products can use CFC propellants because they are exempt from the 1978 ban
on CFC's for aerosol products. These products are often ingested or inhaled, therefore
toxicity of the propellant is very important. Another option may be the use of
compressed gases, such as CO2 or compressed air. Nitrous oxide, also known as
"laughing gas," cannot be used because of the physiological effects of the N20.
5.2.6 Hair Lusterizers
Hair lusterizers are used especially by persons with very curly hair. These
products do not contain the film-forming resin found in hair spray, but they contain
5-3
-------
silicone fluid or mineral spirits to convey a sheen or a look of healthy hair. No data are
available on alternative dispensing technologies or on the possible use of compressed
gases. These products are also available as water-based products using DME as a
propellant.
5.2.7 Hair Mousse
Hair mousse is a relatively new product designed to provide both hair setting and
conditioning qualities. Hair mousse (French word for "foam") is a water-based
formulation that employs a specialty polymer to achieve this goal. An aerosol dispenser
is needed to generate the foam structure. No data are available on alternative dispensing
technologies. Compressed gases cannot be used because they will not produce a quality
foam.
5.2.8 Colognes and Perfumes
Aerosol colognes and perfumes are used for convenience. The aerosol dispenser
can produce a consistently fine spray pattern, with good directional control. Alternatives
to aerosol colognes and perfumes include air-aspirated sprays and dab-on liquid
concentrates. Compressed gases could be used as an alternate propellant. However,
spray patterns would be adversely affected and higher pressures may preclude the use of
glass containers which are generally preferred by consumers.
5.2.9 Other Personal Products
This is another category that also contains a wide variety of products and
represents only 0.1 percent of the aerosol market. Some examples include suntan lotions,
body mousses, and depilatories. Because of the variety of products, it is difficult to make
general statements about why these products are packaged in aerosol sprays or about
alternative dispensing technologies. These products can be propelled with HC's, DME,
5-4
-------
or compressed gases. Alternative packaging forms, such as lotion, liquids, etc., could
also be used. However, these decisions must be made for each specific product.
5.3 HOUSEHOLD PRODUCTS
5.3.1. Room Deodorants and Disinfectants
Room deodorants and air fresheners are packaged in an aerosol form because the
aerosol spray results in small particles, which remain airborne longer. The aerosol
product can be dispersed in a large room very quickly with rapid results. In the case of
disinfectants, the aerosol spray allows the consumer to apply the product in concentrated
form into wastebaskets, trash cans, and other surfaces.
Room deodorizers could be marketed in containers such as Exxel® and mechanical
pumps. The primary consideration is whether the dispenser can produce small particles
that will stay suspended. Solid room deodorizers are also very popular products, second
only to the aerosol form in market share. There are also liquid deodorizers, such as
"Air-wick ." No comparisons have been made to quantify the difference in VOC
emissions from these alternate technologies.
Disinfectants are also available in liquid form, usually as part of a cleaning
solution. The effectiveness of a disinfectant product depends on the amount of active
disinfectant in the formulation. The purpose of the aerosol package is to make the
product more effective, efficient, and easy to use. Therefore, whether to use the product
as an aerosol or in the liquid form is a matter of application requirements. However, the
aerosol packaging form may result in less product waste, thereby decreasing the total
VOC's emitted.
Most current deodorizing and disinfectant sprays are propelled by compressed gas.
However, formulation data shows that the HC-propelled products have lower VOC
5-5
-------
contents for the same product weight.2 Additionally, the spray from the compressed gas
products may not be as uniform as the two-phase HC propellant products. Another
alternative for reducing VOC emissions from these products is reformulating them as
water-based formulations. One of the more popular air fresheners is already using a
water-based formulation.
5.3.2 Window Cleaners
Window cleaners are typically water-based formulations with 5 to 15 percent
VOC (alcohol) and a small amount of detergent. Aerosol window cleaners are
convenient products for those who do not want to use a trigger pump or finger pump
dispenser. Aerosol glass cleaners usually dispense a foam that does not drip or run as
quickly as the mechanical pump products, thereby making the product more efficient.
Window cleaners that use the finger or trigger pump dispenser are more popular than the
aerosol product, because they are usually less expensive than the aerosol versions.
No comparisons have been made to evaluate the effect on VOC emissions of
switching from mechanical pumps to aerosol sprays. These products could be propelled
with compressed gases. However, the compressed gases will not produce a foam, which
is a major selling point for the HC-propelled product. Dimethyl ether propellants are not
used because the formulation is already a water-based formulation.
5.3.3 Oven Cleaners
Aerosol oven cleaners are convenient products for cleaning a dirty oven.
Cleaning an oven with an aerosol product takes less time than with liquid abrasive
compounds. Furthermore, many of the newer oven surfaces are not made to withstand
cleaning with abrasives. Oven cleaners are often formulated with very caustic, anhydrous
chemicals. Therefore, the aerosol product has the further advantage of minimizing the
contact of the consumer with the chemicals. Most aerosol oven cleaners do not contain
5-6
-------
large concentrations of VOC's (only 5 to 6 percent HC propellant) because of the
flammability potential when exposed to an oven pilot light.
The most popular alternative to the aerosol oven cleaner is the self-cleaning oven.
This does not require the use of chemicals. Baked-on grease and food on the inside of
the oven is baked off at high temperatures. One possible drawback of this alternative is
that VOC's are be emitted when the grease and food is volatilized. Other alternatives
include oven cleaner pads and brush-on oven cleaners. However, unlike these
alternatives, the aerosol oven cleaner allows the consumer to apply a uniform coating of
foam to the entire interior of the oven. There are no data to determine the applicability
of alternate dispensing technologies.
5.3.4 Hard-Surface Cleaners
The aerosol hard-surface cleaner is used in various cleaning duties, such as
bathroom and kitchen cleaning. Often the aerosol product is dispensed as a foam. These
products are convenient to use because they require no mixing or dilution and can be
used immediately. The aerosol package allows the consumer to apply a uniform coating
of cleaner to the entire surface. Also, the aerosol-generated foam does not drip or run as
fast as the liquid products. Hard-surface cleaners are all water-based formulations and
contain 10 to 25 percent of VOC's.
Alternative dispensing technologies include liquids, powders, and mechanical
pump sprays. Aerosol products have a mid-level market share compared with these other
dispensing technologies. These alternative package forms may be more difficult to use
because it is more difficult to apply a uniform coating of the cleaner. However, no
specific comparisons have been made to evaluate the different level of emissions resulting
from using the aerosol products versus the other packaging forms.
5-7
-------
5.3.5 Carpet and Rug Cleaners
Aerosol carpet and rug cleaner is used for both small and large carpet cleaning.
For example, some consumers may use these products to clean a spill on a small area of
carpet, and some may use them to clean the entire carpet. These products are convenient
to use since the cleaning materials are already premixed in the correct proportions.
When the products are used according to directions, they are capable of providing results
better than vacuuming alone, but probably not as good as professional cleaners. Another
advantage is that the aerosol package allows the consumer to apply the cleaner at any
time. Immediate treatment may prevent the stain from setting, which might otherwise
require professional cleaning. These products are already water-based formulations and
contain only 5 to 10 percent HC propellants.
Alternatives include mechanical pump sprayers, liquid and dry spot removers,
rented cleaning equipment, and professional rug and cleaning services. The mechanical
pumps will not produce a foam, which is an important feature of the aerosol package.
The latter options are typically more expensive than using aerosol products. No
comparisons have been made to evaluate the effect on emissions from switching from the
aerosol package to the mechanical pump. Compressed gases are not used because the can
must be inverted when applying the product to the carpet.
5.3.6 Spray Starch Laundry Products
Spray starch is applied to clothes before they are ironed to keep clothes neat and
crisp. The aerosol spray starch is the most popular form of starch application, mainly
because it is always ready to use. Another advantage of the aerosol package is that it is
better suited to maintain sterile conditions that are needed to prevent the growth of
microorganisms. The starches are water-based formulations, therefore, the only VOC
emissions are associated with the propellant (some products contain 5 to 9 percent HC
propellant). Other spray starches use compressed gas as a propellant.
5-8
-------
Alternatives to the aerosol form include mechanical pumps, bulk starches, and
professional laundering services. The mechanical pump technology is easy to use but it
does not produce as fine a spray as the aerosol product. The bulk or powder starches
require extensive preparation. Laundering services are more expensive than self
application. None of these alternatives will result in VOC emissions.
One evaluation of aerosol versus nonaerosol starch products has been made for the
CARB. This study showed that the aerosol products were the easiest to use. Nonaerosol
pumps were the next easiest. The bulk starches were found to be the most efficacious
per unit cost, but consumer acceptance was very low because of the inconvenience.
5.3.7 Fabric Finish Laundry Products
Aerosol fabric finish is used to obtain the same crisp feel of starch with less
stiffness. These products were originally developed especially for synthetic (polyester)
blends, but they can also be used with straight cotton or high-cotton blends. No data are
available on alternatives to the aerosol fabric finish. However, these products could
possibly be adapted to mechanical pump dispensers.
5.3.8 Pre-Wash Laundry Products
Aerosol pre-wash products are used to remove stains or to pretreat excess dirt.
These products contain a mild detergent or a solvent (paraffinic HC) for stain removal.
An aerosol pre-wash may contain up to 30 percent water in the formulation.
Alternative dispensers include mechanical pumps sprays and semisolids (sticks).
Only one comparison has been made of the efficacy of aerosol, pump, and direct-delivery
laundry pre-wash products. Again, American Research and Testing performed the study
for CARB. The study showed that stain-removal efficacy was dependent on the stain and
the fabric. The aerosol formulation had improved performance on oily stains.
5-9
-------
Nonaerosol products were more effective in removing tea and grass stains. There are no
data to evaluate the use of compressed gas.
5.3.9 Furniture Waxes and Polishes
Aerosol furniture wax and polish are the most popular forms of these products.
They are convenient, allowing the user to spray a uniform amount of wax over the entire
surface. The furniture polishes are water-based formulations that contain silicone
emulsions.
Alternatives include mechanical pumps and semisolids (paste wax). No
comparisons have been made of the effect on emissions from the aerosol form versus
emissions from the mechanical pumps. The primary drawback to paste wax is the
difficulty of application and removal. Compressed gases may be an option, but there
may be problems because the containers need to be used at all angles.
5.3.10 Furniture Cleaners
Aerosol furniture cleaners are used for cleaning cabinets, paneling, and other
surfaces that have relatively thin varnished or lacquered surfaces. These products are
anhydrous because the water can penetrate the wood and deteriorate the finish.
Alternatives to HC-propelled cleaners include mechanical pumps, liquid forms, and
compressed gas propellants. Because all of these alternatives probably consist of similar
formulations, possibly little or no reduction in VOC emissions would occur.
5.3.11 Other Household Products
Other household products include shoe polishes, dyes, leather dressings, antistatic
sprays, and caulking and sealing compounds. These products are so diverse that no
general statements can be made as to what specific alternatives would be applicable.
5-10
-------
There may be some alternate dispensing technologies that are applicable, such as
mechanical pumps for antistatic sprays and dyes. Almost all of these products are also
available in other package forms such as creams and lotions. There are no data to
determine whether compressed gases could be used, nor is there any information
concerning water-based formulations.
5.4 AUTOMOTIVE/INDUSTRIAL PRODUCTS AND HOUSEHOLD LUBRICANTS
A segment of the aerosol industry supplies products to the industrial sector. These
products are consumed during the manufacture of other products and are not sold in
ordinary consumer outlets. While generally priced higher than normal aerosol products,
these aerosols provide a safe, effective solution to many industrial needs. The alternative
to these aerosols would be products of equal or similar VOC content which may not be as
safe or efficient as aerosols.
5.4.1 Lubricants and Silicones
This category includes penetrating oils, demoisturizers, rust proofing, and mold
releases. Penetrating oils are a major product category. These products (such as WD-
40 ) contain mineral or silicone oils, additives, and a small amount of propellant. One of
the features of the aerosol package form is that an extension tube can be attached to the
actuator to direct the spray into otherwise inaccessible areas. The other products in this
category have uses outside the consumer product area.
The oil can is the most common alternate dispensing technology for the heavier
and more-viscous products. However, the lighter and less-viscous oils cannot be
dispensed with an oil can. No data are available to determine if non-HC propellants can
be used with these products.
5-11
-------
5.4.2 Carburetor and Choke Cleaners
Carburetor and choke cleaners consist of approximately 60 percent toluene or
xylene, 30 percent acetone or alcohol, and 10 percent HC propellant. The active
ingredients are flammable solvents, so the aerosol package can provide desirable safety
qualities. The performance and efficiency of the aerosol package is good, because the
valve can be fitted with an extension tube to allow the consumer to spray otherwise
inaccessible areas, with little overspray.
These products are also marketed as liquids and gas tank additives. The liquids
are essentially the same solvents as the aerosol version. However, because it must be
brushed on, more waste may result from spillage during application. The gas tank
additives cannot replace the aerosol product because it will only clean the internal parts of
the carburetor. They will not free sticking linkages on the outside. Professional
carburetor cleaning is also an option. It often involves complete disassembly and
replacement of gaskets and seals. Also, auto mechanics generally use a solvent degreaser
(cold cleaner) for parts cleaning. This alternative is more expensive than the aerosol
product and may emit VOC's as well. The carburetor cleaners could not be reformulated
as water-based products because the efficacy of the product depends on how well the
formulation dissolves grease and shellac buildup. Water will not act as a solvent for
these compounds. Additionally, it is undesirable to contaminate a carburetor with water.
These products may be able to be propelled with compressed gases.
5.4.3 Engine Starting Fluid
Aerosol engine starting fluid consists of diethyl ether (90 percent), plus CO2
propellant. This product is used to help start gasoline and diesel engines, especially hi
cold weather. The aerosol package is an essential part of the safety of the product,
because the ether is highly flammable. In a liquid form there is a danger of spillage or
using too much liquid, which could cause an explosion or a fire in the carburetor. In
5-12
-------
addition, much of the liquid product would be lost to evaporation, resulting in VOC
emissions.
5.4.4 Tire Inflator and Sealants
A tire inflator consists of a water dispersion of resin, ethylene glycol, a trace of
surfactant, and approximately 25 percent propellant. These products allow the consumer
to seal and reinflate a flat tire, thus avoiding a costly and time-consuming tow truck call.
The tire can then be removed from the car at a later, more convenient, time. This
product is only available as an aerosol. The only alternative to HC propellants is a
fluorocarbon propellant. Some of the higher-pressure HCFC's could be used.
5.4.5 Cleaners
This category consists of automotive upholstery cleaner, leather and vinyl cleaner,
whitewall tire cleaner, and tire dressing. These aerosol cleaning products may dispense
in the form of a foam or a mist. The foaming action (upholstery cleaner) is intended to
improve the product efficacy by decreasing the tendency for the product to run or drip on
vertical surfaces. The foam is then scrubbed into the surface and rinsed away. The
whitewall tire cleaner may contain deodorized kerosene, so the aerosol package allows a
safe method for handling the flammable material. The tire cleaners may also contain
dangerous ingredients (caustic material), which make the aerosol dispenser an ideal
package because it will limit the contact a consumer has with the dangerous chemicals.
Most of these products are also sold in mechanical pump packages. Some leather
cleaners are sold in cream or lotion forms. No information is available for determining
the effect on emissions of switching from HC-propelled products to mechanical pumps,
creams, or lotions. Some whitewall tire cleaners may be propelled by
5-13
-------
5.4.6 Brake Cleaners
Aerosol brake cleaner consists of either alcohol (methanol or ethanol) or
chlorinated solvents and an HC or compressed gas propellant. It is used to clean parts
on hydraulic brake systems. The aerosol package is an essential part of the product
efficacy, since the solvent is sprayed quickly and forcefully from the can. The aerosol
also has safety advantages, since the solvents may be toxic. An alternative is to brush on
a solvent. Because the solvent content of the aerosol and liquid product is similar,
differences in VOC emissions would depend on possible spillage and waste during
cleanup.
5.4.7 Engine Degreasers
These products consist mostly of deodorized kerosene, xylenes, and a small
amount of surfactant. The aerosol form allows the consumer to uniformly spray the
degreaser over the engine. After the solvents have had time to dissolve the deposits, the
consumer simply hoses off the engine with running water.
Alternatives to the aerosol form of degreasers are steam cleaning and self-service
cleaners (coin-operated car washes). Both of these options are less convenient, because
the consumer has to either pay for the engine to be cleaned professionally, or has to drive
to an establishment that offers self-service cleaning facilities. An alternative to HC-
propelled degreasers are CO2-propelled products, which may be preferred over HC
propellants in that flammability may be reduced. The formulation of the engine
degreaser is designed to act as a surfactant that will allow grease to be soluble when
washed. Therefore, a water-based formulation may not work as effectively.
5-14
-------
5.4.8 Spray Undercoating
Spray undercoating is used by consumers to add a sound-deadening or corrosion-
resistant layer to the automobile underside. This aerosol product is a substitute for
professional undercoating and costs much less. The undercoating consists of
approximately 50 percent pigments and solids and 50 percent solvent/propellant.
Alternatives to the aerosol product include brush-applied and commercially applied
undercoatings. The brush-applied alternative would reduce product efficacy because of
the difficulty in reaching all areas underneath the automobile. Because the undercoating
is only effective if it covers all exposed surfaces, brush application might allow corrosion
to occur. Also, the brush-applied method may require a substantial amount of solvent to
be used for cleanup. Professionally applied undercoatings are more expensive than the
consumer-oriented aerosol product. No data are available on non-HC (compressed gas or
DME) propellants used with the products currently on the market.
5.4.9 Windshield and Lock De-icers
De-icers typically contain methanol as the primary active ingredient. The aerosol
package allows the consumer to safely use the toxic material. Also, the sealed can
ensures that the volatile methanol does not evaporate. At least one windshield de-icer
formulation is propelled with CO2- Compressed-gas propellants are well suited for use in
cold conditions because the inside can pressure is not as affected by low temperatures.
The vapor pressure of liquified gas propellants is suppressed by low temperatures. As
with all products that use compressed gas propellants, the consumer must be careful to
always operate the can in the upright position. Because the product is used in cold
weather, water-based formulation would have problems, such as freezing.
5-15
-------
5.4.10 Other Automotive and Industrial Products
This category consists of a wide variety of products that make up a very small
portion of the aerosol market. Because of the variety of products, it is difficult to make
general statements about why they are packaged in aerosol sprays or about alternative
dispensing technologies.
5.5 PAINTS, PRIMERS, AND VARNISHES
Aerosol spray paints are marketed as being more convenient, less messy, and
faster to use than brush-on paint. For many applications, aerosol paints result in a
higher-quality finish than brush application. Also, aerosols do not require; an expensive
air compressor and spray gun to apply a high-quality paint finish. Aerosol spray paint is
especially useful when painting irregular surfaces.
Brush-on paint is available for many types of finishes. Conventional spray
equipment (air compressors and spray guns) are used by professionals. Preliminary tests
by the aerosol paint industry show that despite the high VOC content of aerosol spray
paints, VOC emissions may be less than with other methods of application if emissions
from cleanup solvent emissions are considered.
The formulation of an aerosol paint is single-phased and contains a HC propellant.
That is, the propellant is dissolved in the formulation and acts as a solvent. Therefore,
compressed gas is not an alternative. An alternative may be to use DME, which may
allow reformulation to lower-solvent-content paints.
5.6 INSECT SPRAYS
All insecticides, such as total release foggers, crack and crevice residual
insecticides, and wasp and hornet sprays, etc., are registered with the federal
government. Any change in content will require testing and extensive administrative time
5-16
-------
and effort to accomplish the new registration. Toxicity and efficacy studies require EPA
registration and approval under the Federal Insecticide, Fungicide, and Rodenticide Act.
Any changes would be very costly (> $100,000), and this cost would be passed on to the
consumer.
5.6.1 Space Insecticides
Space insecticides include flying insect killer, house and garden spray, total
release room fogger, patio fogger, and wasp and hornet spray. These products are
packaged in aerosol form because of the unique spray characteristics. In the case of a
flying insect killer or a house and garden spray, a fine particle size and good dispersion
is needed so that the chemical remains airborne long enough to come into contact with
the insects. Foggers are only possible because of the aerosol package because a very fine
particle size is needed to penetrate all areas of a room. Wasp and hornet sprays must
have a powerful, consistent propellant to produce a stream of insecticide that will contact
the insect up to 20 feet away. A further advantage of the aerosol package is that the
sealed, premixed aerosol package eliminates the need for the consumer to handle the
toxic ingredients.
Before the development of aerosol insecticides, the hand-operated "FLIT" gun was
used to disperse the insecticide. A more recent product was the "No-pest" strip that is
essentially a controlled release package. Both of these technologies have been abandoned
in favor of the aerosol package because of the efficiency and ease of use of the aerosol
product. Another alternative available to the consumer is a professional exterminator.
The exterminator is much more expensive than an aerosol product, and is usually only
used for severe insect problems.
In the past, space insecticides were propelled by CFC's. Currently, with few
exceptions, they are propelled by HC propellants. Some of the wasp and hornet sprays
are pressurized with compressed gases. Expanded use of compressed gases is hampered
5-17
-------
by the problem of the degrading spray pattern resulting from the decreased pressure as
the product is used up. This could be especially critical with wasp and hornet spray,
since it is important that the product deliver a full force all the time.
Historically, insect sprays have employed solvent-based formulations. Recently,
with the increased use of DME as a propellant, manufacturers have started marketing
more water-based products. In some instances, however, safety concerns regarding
electrical applications may need to be addressed (e.g., the use of wasp and hornet sprays
in proximity to high voltage electrical apparatus). This trend should help reduce the
amount of VOC's emitted from space insecticides. Dispensing technologies that could be
used include "FLIT" guns and insecticide strips. However, presently no data are
available to evaluate the effect of these alternative dispensers on reducing VOC
emissions.
5.6.2 Residual Insecticides
Residual insecticides include ant and roach killer and premise sprays (carpet,
bedding, furniture, etc.), and wasp and hornet sprays. Ant and roach killers require a
fine spray to penetrate cracks and crevices where the insects live. Dispensing
technologies other than aerosol sprays are available. Ant and roach killers are available
in dry poisons and bait traps. These residual insecticide products are a also available in
mechanical pump dispensing containers. Other dispensing technologies that could be used
include Airspray and Werding Nature Spray .
With few exceptions, residual insecticides are propelled by HC propellants.
Dimethyl ether could possibly be used so that the products could be reformulated as
water-based products. Compressed gases are not used because of limitations on operation
at some angles or inverted positions. Also, a consistent and fine spray pattern is needed
throughout the life of the product, and compressed gas propellants are characterized by
degrading spray pattern as the product expended.
5-18
-------
5.6.2 Insect Repellents
Insect repellents are products that are sprayed on the body. Some of these
products are packaged in the aerosol form, mainly because of convenience. Personal
insect repellents require a fine spray to apply the action chemical uniformly to the desired
surface. Personal repellents are available in sticks and lotions, which can be an attractive
option because the transfer efficiency of a lotion is virtually 100 percent, whereas the
transfer efficiency of sprays is only about 65 percent. No data are available to determine
the effect of these alternative dispensing technologies on reducing VOC emissions.
5.7 FOOD PRODUCTS
These products include pan sprays, whipped cream, cheese topping, and cake
decoration. They are packaged in the aerosol container mainly for convenience. The
major product in this category is pan and flavoring sprays that consist of com oil,
alcohol, lecithin, and HC propellant. The HC propellant is essential to the product
because it lowers the viscosity of the mixture. The pan spray is valued for its health
benefits (low fat, no cholesterol) and is a popular substitute for butter or margarine.
Whipped cream is the next most popular aerosol food product.
Conventional bottled vegetable oil is a substitute for the pan sprays. Synthetic
whipped toppings are available in plastic tubs. Cheese toppings and cake icing are also
available in pre-prepared nonaerosol packaging. Besides these pre-prepared products, all
of these products can be made in the kitchen.
Whipped cream is propelled by N2O. The minor products (cheese topping and
cake icing) are packaged in piston cans that may be adaptable to compressed gas
propellants. It may not be feasible to replace HC propellants in the pan and flavoring
sprays with compressed gases because these alternative propellants will expel the products
in a solid stream unusable by the consumer.
5-19
-------
5.8 ANIMAL PRODUCTS
This category includes flea and tick killer, veterinary products, and shampoos.
Flea and tick killer sprays are similar to other insect sprays. These products are
desirable for their ease of use and ability to uniformly cover the pet's entire body. No
data are available on veterinary products.
Flea and tick killers are available in liquid form, mechanical pumps, powders, and
treated collars. The powders are less desirable from a consumer's point of view because
uniform coverage of the pet is difficult to achieve. The mechanical pumps can be
difficult to use on larger animals because of finger fatigue. No data are available to
estimate the effect on emissions of switching from aerosol flea and tick spray to a
mechanical pump spray. Also, because the container may have to be inverted to spray
some areas of the pet, a compressed gas propellant is not an attractive option.
5.9 MISCELLANEOUS PRODUCTS
This category covers products that do not fit into other categories. Examples
include skin chillers and cleaners, boat/air horns, computer tape developer, electronic
diagnostic chillers, herbicides, and fungicides. Propellants for these products include
CFC's (exempted for these applications) and VOC's. This category is so diverse it is
difficult to make general statements concerning alternatives. Options might include
compressed gases, water-based formulations, mechanical pumps and alternate packages.
5.10 REFERENCES
1. "1989-1990 Buyer's Guide," Aerosol Age. Vol. 34, No. 10. October
1989.
2. Radian Corporation. Control Technology Overview Report: Volatile
Organic and Chlorofluorocarbon Use in Aerosol Products. U.S. EPA, Air
and Energy Engineering Research Laboratory. 1989.
5-20
-------
3. Meeting Summary. National Aerosol Association participation in EPA
study of VOC's in consumer aerosol products. July 2, 1990.
4. Meeting of National Aerosol Association and U.S. EPA, Office of Air
Quality Planning and Standards. Durham, North Carolina. May 7, 1991.
5-21
-------
SECTION 6.0
CONCLUSIONS
This study of aerosol products and packaging systems was undertaken in order to
present information on (1) the functions, attributes, and applications of aerosol consumer
and commercial products; (2) the technology associated with aerosol delivery systems and
the functions and interactions of the system components; and (3) possible opportunities
for reduction of emissions of VOC's from these products, primarily through reduction in
their VOC content. Based on the information available at the time of the study, the
following conclusions were reached:
1. Consumer products are dispensed in aerosol form for specific reasons that relate to
each product. Some of the reasons include controlled application, consumer
health and safety, and consumer convenience.
2. Aerosol products function as systems comprised of the product, the propellant, the
valve, and the container. The product and propellant comprise the formulation.
As in any system of interrelated components, modification of one or more system
components must be carried out judiciously in order to preserve the functionality
of the system. Consequently, seemingly expeditious measures to reduce the VOC
content of aerosol products (e.g., changing from an aerosol to a mechanical pump
spray, switching to non-VOC compressed gas propellants, changing to water-based
formulations, etc.) may not achieve the desired results in many cases.
3. Alternative dispensing technologies are available to reduce the VOC content (and
emissions) of various products while allowing the products to be delivered as a
spray or mist. However, each of these technologies has limitations, sometimes
including increased VOC levels, and none of these technologies can be applied to
all products.
6-1
-------
4. A widely held misconception is that most aerosol products employ CFC's as
propellants and contribute to stratospheric ozone depletion. While a very small
number of aerosol products are propelled by CFC's (e.g., Pharmaceuticals,
military specification products, aviation products, etc.), these uses are exempt
from the 1978 ban on the use of CFC's in aerosol products. The vast majority of
aerosol products currently employ hydrocarbons (propane, n-butane, and
isobutane) and dimethyl ether as propellants.
5. Considering the complexity of the interactions among the components of aerosol
packaging systems, the variety of specific functions that aerosol products fulfill in
individual product categories, and the difficulty in achieving across-the-board
VOC reductions from aerosol products, it may be inappropriate to consider
aerosol products a discrete category of products for regulatory purposes. The
most realistic and manageable approach may be to consider the aerosol delivery
system as one of several packaging forms available in each separate category of
consumer and commercial products regulated. Using this approach, opportunities
for VOC reductions through reformulation, change in delivery method, use of
alternative technologies, etc. could be evaluated on a product by product basis.
6-2
------- |