Chemical & Engineering News,
September 25, 1995

Copyright © 1995 by the American Chemical Society.

EPA, industry sector agree on VOC limits for wood furniture coatings

In an instance of industry and government working together, the Environmental Protection Agency and the furniture industry have agreed on volatile organic compound (VOC)-emission standards for wood furniture coatings.

Unlike the huge architectural and industrial maintenance categories, (for which government and industry cannot agree on standards) wood furniture coatings account for only about 4% by volume of all coatings sold. Wood furniture makers are largely concentrated in North Carolina and in the Grand Rapids, Mich., area. With fewer paint manufacturers and users than those that fall into the architectural and industrial maintenance categories - which account for 65% of all coatings sold by volume - this industry more easily could agree on standards.

The industry ultimately decided on a VOC standard based on two major categories: waterborne top coats, and solvent-borne base and top coats. And because paint users often mix in additional solvents to thin coatings for spray applications at furniture painting facilities, the industry agreed to measure VOCs and hazardous air pollutants (HAPs) expressed in pounds for every pound of solid material applied to the furniture surface.

None of the coatings in these categories may emit more than 2.3 lb VOC per lb of solids. The industry also agreed to limit HAP emissions to 1.0 lb volatile HAP per lb of solids for most categories of coatings applied at existing furniture coating facilities. These standards represent a 30 to 40% reduction in VOCs and HAPs compared with coatings now in use.

Gerry M. Currier, vice president of Akzo Nobel's wood business unit in High Point, N.C., attributes the success of negotiations to the diversity of negotiators. "Anyone who would sue anyone else was at the negotiating table" to determine VOC limits for wood furniture coatings. The negotiators included wood furniture manufacturers and their associations, the National Paint & Coatings Association, material suppliers, and environmental groups, as well as state and federal EPA regulators.

(lb per lb
Waterborne top coats 0.8
Higher solids sealers and top coats
Sealers 1.9
Top coats 1.8
Acid-cured alkyd amino vinyl sealers 2.3
Acid-cured alkyd amino conversion varnishes 2.0

The new regulations allow furniture coating makers and users a large degree of latitude in formulations, says Currier. Users may switch to waterborne technology, high-solids low-solvent coatings, or radiation-curable coatings. They can also install afterburners to consume VOC and HAP emissions, or they can use exempt solvents, such as acetone, to meet the new regulations. "We have to examine the patient before we can prescribe any one of several different remedies," he says. "There is," he cautions, "no one right answer. Furniture coating users will have to choose their suppliers carefully because they will have to pay a $25,000-per-day maximum fine for not complying with regulations," when the regulations go into effect beginning in 1997.

Two material suppliers, Bayer and Rohm and Haas, have worked together to produce a waterborne polyurethane coating for wood furniture with VOC and HAP emissions of less than 0.1 lb per lb of solids. Bayer developed a water-reducible polyisocyanate, Bayhydur XP-7063, while Rohm and Haas developed a hydroxy-functional acrylic, emulsion E-3275. "Flow additives in the two-part system are the only source of VOCs," says Michael J. Dvorchak, wood coating manager of technology for Bayer.

A potential drawback to the ultra-low-VOC/HAP system the two firms have developed is the cost a user must absorb to switch steel spray lines and spray guns to stainless steel. If customers decide to make the switch, they will have a system that allows them to build the hand-rubbed finish often desired on wood furniture because the system can be sanded and polished, says Dvorchak.

Also under development, says Dvorchak, are urethane systems that contain 80 to 90% solids. Although not yet available commercially, this new solvent-borne system will have viscosity comparable with the industry standard, nitrocellulose lacquer (formulated at 16% solids). VOC levels should satisfy the standards.

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