United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/SR-95/160 February 1996
4>EPA Project Summary
Research and Product
Development of Low-VOC Wood
Coatings
Eddy W. Huang
This project was cofunded by the
South Coast Air Quality Management
District (SCAQMD) and the U.S. Envi-
ronmental Protection Agency (EPA) to
develop a new low-volatile organic com-
pound (VOC) wood coating. Traditional
wood furniture coating technologies
contain organic solvents that become
air pollutants as the coating cures; miti-
gation by add-on control devices would
be energy intensive. Air emissions can
be reduced through the pollution pre-
vention approach of shifting to low-
VOC coatings, avoiding the energy
penalty.
In this project, a new low-VOC wood
coating technology (a two-component
water-based epoxy) was evaluated by
determining its performance character-
istics, conducting application and emis-
sions testing, and assessing the cost
benefits for energy conservation and
air pollution reduction. The composi-
tion of the basic epoxy polymer was
varied with several curing agents.
The resulting top coat was as good
as or better than other low-VOC water-
borne wood furniture top coats for ad-
hesion, gloss value, dry time, hardness,
level of solvents, and chemical and
stain resistance. The VOC content of
the clear and the white pigmented top
coats was less than 10 g/l. Cost of this
low-VOC wood coating is comparable
to that of low-VOC coatings. Improved
dry times were identified as being criti-
cal for product improvement. A mar-
keting plan was developed. At least one
major coatings manufacturer expressed
interest in participating in a product
feasibility study.
This Project Summary was developed
by EPA's National Risk Assessment
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
The annual U.S. market for wood coat-
ings is approximately 240,000 m3 (63 mil-
lion gal). Assuming an average VOC
content of 600 g/l (5 Ib/gal), 146 kg (315
million Ib) of volatile organic compounds
(VOCs) are emitted into the air each year
from presently used waterborne and
solventborne systems for coating wood.
The use of "VOC-free" formulations would
reduce such air pollution.
The worldwide coatings market is esti-
mated to be in excess of $34 billion annu-
ally. The U.S. market is about $14 billion
segmented in three main categories: (1)
Architectural Coatings (AC); (2) Product
Coatings used by original equipment
manufacturers (PC-OEM); and (3) Special
Purpose Coatings (SPC). In most mar-
kets, customers' needs are being satisfied
by a relatively small number of coatings
companies, many with sales approaching
$1 billion. A significant number of coat-
ings operations are part of large chemical
groups such as AKZO, Ashahi, BASF,
DuPont, ICI, Mitsubishi, and PPG Indus-
tries. The industry also includes a number
of very large independents, like Beckers,
Jotun, Kansai, Lilly, Nippon Oil & Fats,
Nippon Paint, Reliance, Sadolin, Sherwin
Williams, and Valspar. The profile of the
-------
coatings industry and the markets it serves
has undergone dramatic change in the
last decade. The strongest thrusts have
been forced by such things as huge busi-
ness realignments, consolidations and re-
ductions in the number of coatings
companies, and the impact of environ-
mental compliance.
The wood coatings industry can be
separated into two categories having dif-
ferent requirements with respect to appli-
cation technique: flat stock coating and
the coating of three dimensional objects.
Flat stock is usually coated on a continu-
ous coating line of some type, while more
complicated three dimensional objects,
such as furniture, usually require spray
application and batch drying. The kitchen
cabinet industry uses nitrocellulose (N/C)
for the high end products and conversion
varnish/conversion lacquer for the bulk of
its finishing needs. Conversion varnishes
and lacquers contain up to 50% of urea or
melamine formaldehyde resins which are
only partially cured at the low tempera-
tures allowable for wood surfaces; thus
there is a significant level of free formal-
dehyde emanating from the coating
throughout its use life. Formaldehyde has
been designated by the EPA and Califor-
nia Air Resources Board as a suspected
carcinogen. The N/C must be replaced to
meet VOC regulations and the uncured
urea/melamine formaldehyde containing
coatings replaced to meet the very low
concentration of "free formaldehyde" re-
quirements.
Water based products have been intro-
duced to much of the lumber industry to
replace the high VOC materials previously
used on plywood, hardboard, particle
board, and regenerated wood-finger jointed
wood products. These products, however,
exhibit lowered performance properties
such as hardness, toughness, adhesion,
and solvent and stain resistance. Their
second weakness is in energy consump-
tion (i.e., they require long time/tempera-
ture exposure for cure). They may or may
not meet the free formaldehyde require-
ments, which become more exacting each
year.
The purpose of this study was to evalu-
ate a new low-VOC wood coating technol-
ogy by determining its performance
characteristics, conducting application and
emissions testing, and assessing the cost
benefits for energy conservation and air
pollution reduction. The low-VOC wood
top coat selected for this demonstration
project was a two-component, water-based
epoxy coating developed by Adhesive
Coatings Co. (ADCO), San Mateo, Cali-
fornia. The composition of the basic ep-
oxy polymer was varied in combination
with each of several curing agents.
The resulting top coat showed excellent
performance characteristics in terms of
adhesion, gloss value, dry time, hardness,
level of solvents, and chemical and stain
resistance. The VOC contents of both the
clear top coat and the white pigmented
top coat were less than 10 g/l. The coat-
ing performance characteristics and prop-
erties in finished material were compared
with those of other low-VOC waterborne
wood coatings. Finally, the cost benefits
of this low-VOC wood coating, critical ar-
eas for product improvement, the market
development plan, and future research
work are addressed in this report.
This new low-VOC coating's high gloss
and excellent chemical resistance are ideal
for the wood manufacturing industry for
flat stock, for particle, chip, and wood
flower products; spray primers for door
skins; and finishing systems for interior
wood products such as furniture and
kitchen cabinets. This material can be
manufactured using readily available raw
materials and standard resin manufactur-
ing equipment without polluting the atmo-
sphere.
Several large companies that manufac-
ture and supply products used in the wood
coatings industry have been contacted.
The product marketing discussions have
centered on how best to commercialize
specific ultra-low VOC finished coating
applications. Discussions are underway
with two major corporations, both of which
are worldwide suppliers of industrial prod-
ucts and services to the coatings, adhe-
sives, and polymer industry and recognized
as leaders in providing coatings and ancil-
lary products for the wood industry.
Project Description/Results
This new wood coating system consists
of an epoxy component (Part A) and an
amine curing component (Part B). It has
the following performance properties:
(a) Less than 10 g/l (0.1 Ib/gal) VOCs,
(b) Liquid with rapid initial drying char-
acteristics upon application,
(c) Hardness,
(d) Flexibility, and
(e) Chemical resistance.
Four variations of EnviroPolymer—A-1
(EP 180-60), A-2 (EP 200-60), A-3 (EP
510-60), and A-4 (EP H-60)—were used
in this project. Four proprietary curing
agents—B-1 (80-70), B-2 (65-71), B-3 (65-
99), and B-4 (81-93)—were identified as
being the most likely to yield promising
results. Formulations A-1/B-2 and A-2/B-1
were judged to be the most likely to yield
promising test results when applied to a
substrate for further determination of the
coatings performance characteristics (dry
time, gloss, parallel groove adhesion, and
scrape/mar, chemical, and stain resis-
tance).
The final, low-VOC coatings showed
excellent performance characteristics in
terms of adhesion, dry time, gloss, and
scrape/mar resistance, as measured by
standard ASTM methods. The VOC con-
tent of the final formulations was below
the detection limit (10 g/l) of test method
ASTM D 2369.
Several wood furniture manufacturers
and coating suppliers were contacted to
identify wood coating concerns, current
application methods, costs, and critical ar-
eas for product improvements. Marketing
information related to the wood coatings
market was collected. This information was
reviewed to establish what specific data
still need to be collected and how they
should be used in structuring the planned
market survey of wood coating suppliers.
The product marketing discussions have
centered on how to commercialize spe-
cific low/no-VOC finished coating applica-
tions resulting from this wood coating
project.
Based on contacts to date with these
marketing entities, at least one coatings
manufacturer has expressed interest in
participating in joint product feasibility stud-
ies. Upon development of priority high-
value-added products for potential sale
and use in the U.S. wood products market
as contemplated at the conclusion of this
project, ADCO is prepared to enter into
either joint venture agreements or licens-
ing arrangements for commercialization of
low-VOC wood products worldwide.
-------
Eddy W. Huang is with AeroVironment, Inc., Monrovia, California 91016.
Robert C. McCrillis is the EPA Project Officer (see below).
The complete report, entitled "Research and Product Development of Low-VOC
Wood Coatings,"(Order No. PB96-121520; Cost: $19.50, subjectto change) will
be available only from
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
National Risk Management
Research Laboratory (G-72)
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use
$300
EPA/600/SR-95/160
------- |