Increasing concern about the impact of formaldehyde and other VOCs on human health has prompted development of low- and no-VOC adhesives. This technological advancement especially is important given the ubiquity of adhesives in our lives. According to estimates from the European Union, a typical home contains 185 gallons (700 L) of adhesives, either as pure adhesives or as part of other products. As newly formulated green products enter the marketplace, questions arise about their performance and long-term durability. New research and strong testing and performance standards demonstrate that these environmentally friendly products meet today’s c onstruction requirements.
ADHESIVES MARKET
An adhesive is any substance capable of holding two objects together in a functional manner through non-mechanical means. Adhesives are capable of producing a strong, lightweight bond at a relatively low cost when compared to screws, bolts or welds. According to the Bethesda, Md.-based Adhesives and Sealants Council, the North American adhesive industry is forecast to achieve $15.9 billion in revenue and produce 8 million dry pounds (3.6 million dry kg) in 2008.
There are essentially three types of low-VOC adhesive formulas: water-based, which includes latex and acrylics; reactive, which includes silicone and polyurethane; and exempt solvent-based, which includes VOC-compliant solvents. Water-based adhesives are formulated from natural polymers or soluble synthetic polymers. Natural polymers typically are derived from vegetable sources, such as dextrins and starches; protein sources, including casein, blood, fish, soybean and milk albumen; and other animal sources, such as hides and bones. Switching to water-based adhesives from traditional solvent-based adhesives allows manufacturers, contractors and others to significantly reduce VOC emissions during use.
To be accepted in the marketplace, any new, low-VOC adhesive must meet performance standards established by ASTM International, West Conshohocken, Pa. Specifically, ASTM Technical Committee D14 on Adhesives develops standards for adhesives; materials used in compounding adhesives; research on adhesives; and adhesion, including clarification of the nature of adhesion. The committee, which has a membership of approximately 150, currently has jurisdiction of 132 standards. For example, ASTM D905-03, “Standard Test Method for Strength Properties of Adhesive Bonds in Shear by Compression Loading,” covers the determination of the comparative shear strengths of adhesive bonds used for bonding wood and other similar materials.
FORMALDEHYDE AND OTHER VOC CONCERNS
Although soy-based and other natural adhesives have been used to manufacture plywood and other common wood products for the past 70 years, urea- and phenol-formaldehyde products offered better water resistance and lower cost to manufacturers. Concern about formaldehyde offgassing, however, led researchers to re-explore alternative products. In 1985, the U.S. Department of Housing and Urban Development, Washington, D.C., set a maximum allowable VOC concentration of 0.3 parts per million for products used in manufactured homes. In 2004, the Lyon, France-based International Agency for Research on Cancer, part of the Geneva-based World Health Organization, reclassified formaldehyde from “probable human carcinogen” to “known human carcinogen,” elevating the level of public concern.
Then, in April 2007, the Sacramento-based California Air Resources Board, or CARB, approved regulations that will, over time, dramatically reduce the levels of formaldehyde that can be emitted from interior panel products, such as hardwood plywood, medium-density fiberboard and particleboard. Once fully implemented by 2012, CARB officials estimate that its formaldehyde-emission limits will be the most stringent in the world. The rest of the country is expected to follow California’s lead. Within the Washington-based U.S. Green Building Council’s LEED rating system, Environmental Quality credit 4.1: Low-Emitting Materials: Adhesives & Sealants aims to reduce the quantity of indoor air contaminants that are “odorous, irritating and/or harmful to the comfort and wellbeing of installers and occupants.” To receive this LEED point, all adhesives and sealants used on the interior of the building must comply with the South Coast Air Quality Management District Rule 1168, which specifies VOC limits by product type. For example, wood-flooring adhesives must not exceed 100 grams per liter of VOCs. Although products meeting maximum VOC levels established by regulatory agencies—200 g/L—often are labeled as VOC compliant, some manufacturers are able to reduce VOC levels to as little as 3 g/L or less. This competition has set the stage for an evolution in construction adhesives.
PRODUCT ADVANCEMENTS
Concern about IAQ, coupled with the rising costs of petrochemical-based resins and the surplus of soy waste products, have increased attention on developing soy-based products for the woodadhesives industry. The Chesterfield, Mo.-based United Soybean Board has extensively funded wood-adhesives research.
For composite wood panels, soy flour can be converted to a soy hydrolyzate, which reacts with a phenolic resin. Low-cost soy flour can be substituted for up to 40 percent of the more expensive phenol component for use in softwood plywood, oriented strand board and engineered wood products. Researchers also used soy flour in foamed-glue extruded systems for laminating plywood veneers to reduce resin usage. Some of the most exciting research has been in using soy in formaldehyde-free glues for use in interior hardwood plywood. In 2005, Professor Kaichang Li of Oregon State University, Corvallis; Columbia Forest Products, Portland, Ore.; and Hercules Inc., Wilmington, Del., developed an alternate adhesive made from soy flour. Li and his colleagues developed the adhesive to mimic the strong, water-resistant proteins used by ocean mussels to cling to rocks. The soy-based adhesive is stronger than and cost-competitive with conventional adhesives. During 2006 alone, the new soy-based adhesive replaced more than 47 million pounds (21.3 million kg) of conventional formaldehyde-based adhesives, and the team received the 2007 Presidential Green Chemistry Challenge Award from the Washingtonbased U.S. Environmental Protection Agency for its work.
CHOOSING THE RIGHT PRODUCT
Whether selecting a low-VOC or traditional product, architects, specifiers and construction professionals should choose an adhesive that meets the needs of the task. Improper product selection can lead to failure and serious consequences. To ensure products meet projectspecific requirements, specify low- or no-VOC materials in construction documents and ensure that VOC limits are clearly stated in each section of the specifications where adhesives are addressed.
JEFF STEPHENS is principal of Oakland, Calif.-based Planet Relations, a public-relations consultancy for Earth-minded businesses. He can be reached at [email protected] or (510) 663-4462.
STICK TO GOING GREEN
THE FOLLOWING IS A SAMPLING OF MANUFACTURERS THAT OFFER GREEN ADHESIVE AND/OR SEALANT PRODUCTS.
3M
3M Center
St. Paul, MN 55144
www.3m.com
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Columbia Forest Products
222 SW Columbia St.
Portland, OR 97201
www.columbiaforestproducts.com
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Dow Chemical
Dow Center
Midland, MI 48674
www.dow.com
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DuPont
1007 Market St.
Wilmington, DE 19898
www.dupont.com
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Geocel Corp.
P.O. Box 398
Elkhart, IN 46515
www.geocelusa.com
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HB Fuller
1200 Willow Lake Blvd.
Vadnais Heights, MN 55110
www.hbfuller.com
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Henkel Corp.
32150 Just Imagine Drive
Avon, OH 44011
www.greenseries.com
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iLevel by Weyerhaeuser
33663 Weyerhaeuser Way
South Federal Way, WA 98003
www.ilevel.com
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Interlock Industries Inc.
1209 Cleveland Highway
Dalton, GA 30721
(706) 517-8989
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ITW Plexus
30 Endicott St.
Danvers, MA 01923
www.itwplexus.com
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ITW TACC
56 Air Station Industrial Park
Rockland, MA 02370
www.itwtacc.com
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Laticrete International Inc.
One Laticrete Park N.
91 Amity Road
Bethany, CT 06524
www.laticrete.com
nora systems Inc.
94 Glenn St.
Lawrence, MA 01843
www.norarubber.com
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NorthStar Chemicals Inc.
91 Smiley Ingram Road
Cartersville, GA 30120
www.northstarchemicals.com
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OMG Roofing
Products Group
153 Bowles Road
Agawam, MA 01001
www.olyfast.com
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Premier Building Systems
4609 70th Ave. E.
Fife, WA 98424
www.pbssips.com
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SIMALFA
15 Lincoln St.
Hawthorne, NJ 07506
www.simalfa.com
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Sinak Corp.
1949 W. Walnut Ave.
San Diego, CA 92101
www.sinakcorp.com
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Tarkett Inc.
2728 Summer St.
Houston, TX 77007
www.tarkett.com
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W.F. Taylor
11545 Pacific Ave.
Fontana, CA 92337
www.wftaylor.com
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White Lightning Products
101 Prospect Ave.
Cleveland, OH 44115
www.wlcaulk.com
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Wilsonart Adhesives
2400 Wilson Place
Temple, TX 76503
www.wilsonartadhesives.com
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XL Brands
4284 S. Dixie Highway
Resaca, GA 30735
www.xlbrands.com
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Ze-VO Products Group
1290 Worcester Road, Suite 3E
Framingham, MA 01702
www.zevoproductsgroup.com
