A Cooperative
Project between
the U.S. Environmental
Protection Agency and
the Garment and
Textile Care
Industry
FOR
THE
EPA 744-F-99-002, May 1999
US.
Garment and Textile
Care Program
DISCLAIMER: This case
study has been reviewed by the
U.S. Environmental Protection
Agency (EPA) and approved
for publication. It is based on
experiences gained from projects
conducted by EPA's Design for
the Environment Program in
collaboration with partners from
industry, public interest groups,
and research/educational institu-
tions. The information contained
in this document does not consti-
tute EPA policy. Further, mention
of trade names or commercial
products does not imply endorse-
ment or recommendation for use.
All product performance informa-
tion was supplied by the manufac-
turer^) and has not been indepen-
dently corroborated by EPA.
Case Study:
Liquid Carbon Dioxide
(CO2) Surfactant System
For Garment Care
As part of a cooperative effort
between the U.S. Environmental
Protection Agency (EPA) and the
garment and textile care industry, the EPA
Design for the Environment (DfE) Program
recognizes the liquid carbon dioxide (COi)
cleaning process as one example of an envi-
ronmentally-preferable technology that can
effectively clean garments.
Currently, most of the Nation's 34,000
commercial drycleaners use perchloroethyl-
ene (PCE or perc) as a solvent to clean
garments. Since 1992, in response to grow-
ing health and environmental concerns about
perc, EPA has been working in a voluntary
partnership with the drycleaning industry
to reduce exposures to perc. EPAs DfE
Garment and Textile Care Program (GTCP)
encourages professional clothes cleaners
to explore environmentally-preferable
technologies capable of cleaning garments
labeled "dryclean only." Several companies
in the garment and textile care industry have
begun using liquid CO cleaning technolo-
gies for cleaning all types of fabrics. One
company, Micell Technologies, Inc., has
developed a process that utilizes liquid COi
in conjunction with cleaning agents (i.e.,
surfactants). This new technology, named
the Micare™ System, effectively cleans
clothes and is now in commercial use.
Company Background
••••••••••••«•••••
Founded in 1995, Micell Technologies
set out to develop a drycleaning process
that would eliminate hazardous waste
generation, use cleaning agents that do
not pose the environmental and human
health risks associated with perc, lower
energy consumption, save money, improve
cleaning performance, and reduce environ-
mental regulatory burdens. With these
criteria in mind, Micell explored the poten-
tial applications and capabilities of liquid
COi technology. Micell is funded by private
and corporate investors and has raised over
$20 million in equity financing. The head-
quarters of Micell Technologies is located
in Raleigh, North Carolina.
-------
U.S.EFA
Tfte Micell Technologies Production Facility in Midland, Michigan
Micell works closely with the North Carolina State
University (NCSU) College of Engineering and the College
of Textiles. The company's research in the area of liquid
COi cleaning technology has resulted in the issuance of
new patents to Micell. In addition, Micell has licensed
patented cleaning agent components from the University of
North Carolina at Chapel Hill and from Pacific Northwest
National Laboratories. These cleaning agent developments
have been extended by Micell's team of scientists and engi-
neers, resulting in the high performance and cost effective
liquid COi cleaning solution used in the Micare™ system's
MICOi™ machine.
The first drycleaning facility to offer the Micare™ system
is Hangers™ Cleaners located in Wilmington, North
Carolina. Hangers™ is owned and operated by the Williams
family who have been in the drycleaning business since
1941. The Williams family's Hangers™ Cleaners has been
cleaning customers' garments using the COi-based
Micare™ system since late 1998. Micell plans to have
approximately 60 machines in the mid-Atlantic, New
England, and mid-West marketplaces by the end of 1999.
How the Liquid CO* Process Works
Traditional drycleaning systems use perc or petroleum-
based chemicals as the primary cleaning solvent—with
additives and detergents. Wetcleaning utilizes water as its
primary solvent. The liquid CO process employs liquid
CO as the primary solvent, with recyclable cleaning agents.
Carbon dioxide is a naturally occurring and generally
benign substance. At room temperature, CO can exist in
the form of a gas and is therefore used to carbonate soft
drinks and other beverages. In solid form, carbon dioxide
is known as dry ice. At room temperature, CO can also
exist as a liquid if kept in a closed system at an elevated
pressure. Liquid CO has a gas-like consistency and a low
surface tension allowing it to function as a very effective
cleaning medium when combined with detergents.
The Micare™ system uses a large conventional rotating
basket with a detergent system. The system utilizes a spe-
cially designed, 60-pound capacity MICO™ machine
that houses liquid CO. It is similar to today's front-load,
mechanical action machines and features gentle wash
and extract cycles.
A detergent system (containing patented cleaning agents)
enhances the cleaning ability of the liquid CO, allowing it
to remove soils from the garments. After the cleaning cycle,
the machine pulls the mixture of liquid CO and cleaning
agents (i.e., the wash fluid) away from the clothes and then
cleans and reuses the solution. The Micare™ process does
not require heating of the clothes and is therefore gentle
to fabric.
Specifically, the Micare™ System works in the following
stepwise fashion:
• Approximately 60 pounds of garments are
placed inside a large rotating basket in the MICO™
machine and the door is closed, sealing the system.
Vacuum is applied to remove the majority of the air
in the system and CO gas is added to pressurize
the wash tank.
• Liquid CO is then added from the storage tank
along with the Micare™ detergent system in order
to form the wash fluid. The clothes are agitated
for a pre-set time period and with a selected degree
of agitation depending on the nature of the garments
(e.g., delicate, normal, and heavy cycles). Similar
to perc drycleaning machines, the wash fluid is
circulated out of the wash tank through a lint filter
to capture loose fibers and vestige lint. It then passes
through a carbon filter and returns to the wash tank.
At this point, the wash cycle is complete.
• The liquid CO and detergent mixture (i.e., the
wash fluid) is pumped out of the wash tank to
the storage tank. The excess wash fluid (that fluid
left clinging to the garments) is further removed
by a spin extract cycle. A portion of the wash fluid
is then cleaned via a distillation process that removes
excess dirt and detergent. The residue from the distil-
lation process is automatically eliminated from the
machine and collected for shipment back to Micell
for recycling. Carbon dioxide gas is removed from the
wash tank using a compressor and the gas is sent back
to the storage tank for reuse. The Micare™
system is able to efficiently convert CO from a gas
to a liquid, thereby permitting 98 percent of the CO
to be recycled. A nominal amount (10 Ibs) of CO
gas is then vented to the atmosphere.
• After a cycle time of 35 to 45 minutes, the cleaned
garments are removed from the wash tank.
Performance
No independent performance testing has been conducted
to date. The performance information that is presented in
this case study was provided by representatives of Micell
Technologies.
Cleaning
Micell Technologies asserts that the Micare™ system
offers excellent cleaning performance across most garment
components and a wide range of stains and soils. Also,
since liquid CO technology operates at room temperature,
any stains that may remain on a garment after the wash
cycle are not heat-set as can occur with traditional
drycleaning systems. Because stains are not heat-set,
post-spotting is very effective. In addition, the company
has developed effective pre-treatments to further facilitate
cleaning performance.
The Micare^SystemMICO-^Machine
Service Counter at a Hangers™ Cleaners Store
-------
U.S.EFVX
Diagram of the Micare System Cleaning Process
Micell Technologies recently conducted a study of how
well the Micare™ system performed in an actual commer-
cial setting. The study addressed the performance of the
Micare™ system in cleaning approximately 3,000 pounds
of garments that were brought by customers during a one
and a half week period in January 1999 to the Williams
Hangers™ Cleaners in Wilmington, North Carolina. The
key results of the study are as follows:
• The average wash load weight was 42 pounds (not
machine capacity-limited) and the average number
of garments per pound was 1.13.
• Of the 3,000 pounds of garments, 61 percent or
1,830 pounds were dark-colored (with 58 percent or
1,061 pounds of the dark-colored garments having
visible soil) and 39 percent or 1,170 pounds were
light-colored (with 28 percent or 328 pounds of the
light-colored garments having visible soil).
• Overall, 39 percent or 1,170 pounds of the total 3,000
pounds of garments had visible soil.
• Subsequent to cleaning, 12 percent or 360 pounds
of the total 3,000 pounds of garments required
post-spotting treatment.
Color Fastness
One of the most important attributes of any cleaning
system is color fastness. According to Micell Technologies,
the Micare™ cleaning system has color retention perfor-
mance characteristics that equal or exceed those for perc
dry cleaning for a wide variety of colored fabric combina-
tions. Scientists from the College of Textiles at North
Carolina State University, working with Micell scientists,
have compared Micare™ system color fastness with that
of perc dry cleaning for three pairs of black 100 percent
cotton men's chino pants, and three red sweater vests
composed of 90 percent silk and 10 percent cotton. One
of each was drycleaned 20 times in perc, one of each was
cleaned 20 times in the Micare™ liquid COi system, and
one of each was used as a standard control sample and thus
was not cleaned. The color changes in the cleaned garments
were measured using a high-resolution color reflectometer
and the changes were compared to the non-cleaned identi-
cal garment. The black pants and red vest cleaned 20
times in the liquid COi Micare™ System were virtually
indistinguishable from the identical garments that were not
cleaned. However, the red vest and black pants cleaned 20
times in perc resulted in noticeable color loss and fading.
Micell has observed similar trends for many other colors.
The garments that appear to have less than ideal perfor-
mance in the Micare™ System are garments that are pri-
marily composed of triacetate and some acetate fabrics with
specific dispersive dyes (yellow in particular). No abnormal
shrinkage has been observed for acetate garments cleaned
in the Micare™ liquid COi system. Some shrinkage has
been observed for triacetate-based garments only.
Fortunately, triacetate garments are rare and are found in
less than 0.5 percent of the garments that customers brought
to the Hangers™ Cleaners store in Wilmington, North
Carolina. Micell recommends that triacetate garments be
wetcleaned and that the operator use the gentle Micare™
short cycle for the cleaning of acetate garments that contain
the yellow dye.
Relative to traditional drycleaning solvents, fewer dye-
bleeding situations have been observed with use of the
Micare™ system. Micell reports that if a garment is poorly
dyed at the manufacturers facility, there is some chance
that it will bleed, although experience to date shows that
such bleeding is much less likely with the Micare™ system
than with conventional solvents. According to Micell, in the
few observed cases where a garment has bled even slightly,
dye transfer to other garments in the load did not occur.
One example was a red dress with white cuffs. The dress
was processed with a load of light khakis, and no color was
transferred to other garments in the load. However, the red
dye bled onto the cuffs of the dress, imparting a pink tint.
The cuffs on the dress were restored by hand and the gar-
ment was returned to the customer in good condition.
While most leather goods are compatible with the Micare™
process and can be cleaned in the MICOi™ machine, quali-
ty leather care typically requires more than just cleaning the
garment. Leather goods incorporate a variety of dyes, soft-
eners and paints. In many instances, to restore a leather gar-
ment to near original condition, re-dyeing or re-painting is
necessary. The Micare™ cleaning process can be employed
to clean such garments in preparation for further restora-
tion, but cannot substitute for the dyeing and painting tech-
niques offered by specialized leather processors. Finally,
further testing is necessary in order to determine how
broadly the Micare™ process can be applied to cleaning
delicate fur items.
Environmental, Safety,
and Health Impacts
••••••••••••••••
Carbon dioxide is a naturally occurring and generally
benign substance that is routinely ingested in food
products such as soft drinks. The use of liquid COi
technology allows consumers and machine operators
to avoid exposure to traditional drycleaning solvents.
A company named "NuCoi" supplies liquid COi to Micell's
professional clothes cleaning customers. The Micare™
system uses the same beverage-grade bulk COi that NuCoi
delivers to more than 50,000 restaurants and other fountain
beverage dispensers located across the nation.
Environmental stewardship is one of the hallmarks
of the Micare™ system. The residue generated by the
Micare™ system distillation process (i.e., the liquid
COi cleaning and reuse process) is returned to Micell
Technologies for recycling or recovery. Even though COi
and the Micare™ system chemistry are environmentally
benign, the MICOi™ cleaning machine has multiple safe-
guards and process controls that minimize the potential
for leaks and spills. The Micare™ system produces no
hazardous waste, eliminates exposures to traditional
drycleaning solvents, and does not use ozone-depleting
compounds.
Because the Micare™ system liquid COi is stored under
pressure, the MICOi™ machine is designed and constructed
in accordance with the American Society of Mechanical
Engineers (ASME) code for pressurized vessels and sys-
tems. In addition, Micell has considered all applicable
National Fire Protection Association (NFPA) and
Occupational Safety and Health Administration (OSHA)
guidelines.
-------
handling and preferred pick-up location. The marketing
and advertising package includes name, logo, packaging,
uniforms, and point-of-sale, direct mail, print, radio, out-
door, and television advertising.
Other Information
Another company, Global Technologies, Inc., has
developed a liquid COi clothes cleaning system termed
Dry Wash. EPA plans to develop a case study on the
Dry Wash system when commercial performance
information becomes available.
Further, both Micell and Global are exploring other
applications of liquid COi cleaning such as textile
processing and metal cleaning and degreasing.
What is Design for the Environment?
• •••••••• •» ••••••••••••••••••
EPA's Design for the Environment (DfE) Program is a
voluntary initiative that forges cooperative partnerships
among government, industry, academia and environmental
groups. One of the primary objectives is to incorporate
environmental concerns into the design and redesign of
products, processes, and technical management systems.
One of the goals of the DfE Garment and Textile Care
Program (GTCP) is to provide cleaners with information
that can help them run their facilities in a way that is safer
for workers, more environmentally sound, and more cost
effective. To accomplish this goal, the program utilizes EPA
expertise and leadership to evaluate the environmental and
human health risks, performance, and cost tradeoffs among
clothes cleaning technologies. DfE disseminates informa-
tion to all interested parties and assists businesses in
implementing cleaner technologies.
The GTCP is preparing several documents addressing
environmentally-preferable and commercially viable
clothes cleaning technologies. In the near future, these
and other case studies will be available on the GTCP
website and in hardcopy and include:
• Case Study: Water-Based Cleaning System for Suede
and Leather (EPA 744-K-98-017)
• Case Study: Wetcleaning Systems for Garment Care
(EPA 744-K-98-016)
For More Information
• For more information about Micell Technologies,
Inc., contact:
Dr. Joseph M. DeSimone
Co-founder and Chairman
Micell Technologies, Inc.
7516 Precision Drive
Raleigh, North Carolina 27613
Telephone: (919) 313-2102
Fax:(919)313-2101
Visit Micell's web site: www.micell.com
• Contact the EPA Pollution Prevention Information
Clearinghouse (PPIC) to receive an information pack-
et about EPA's DfE Program or the Garment and
Textile Care Program, or to request single copies of
DfE documents, or a revised DfE Publications List:
Pollution Prevention Information Clearinghouse
(PPIC)
U.S. Environmental Protection Agency
401 M Street, SW (7407)
Washington, DC 20460
Telephone: (202) 260-1023
Fax: (202) 260-4659
E-mail: ppic@epa.gov
• Visit the EPA DfE Garment and
Textile Care Program web site:
http://www.epa.gov/dfe/garment/garment.html
• Visit the DfE Program web site:
http://www.epa.gov/dfe
------- |