Alternative Manufacturing Processes
Coating and Laminating Applications
Formaldehyde is used as a wet strength resin in paper coating for architectural finish applications, and a fiber relaxer in fabric coating applications.
- Substitute paper coating resins can be made from polyamide, polyamine, epichlorohydrin and acrylic, as well as polyurethane dispersions. Some of these alternatives pose health concerns. Additional research is needed.
- Formaldehyde resins have been used to improve the wrinkle resistance of garments. However, due to the formaldehyde off-gassing and emission issues, replacements are being investigated. Alternatives that are showing some efficacy include phosphinocarboxylic acid, maleic acid and sodium hypophosphite. Other possible alternatives include glyoxal resins, butane tetracarboxylic acid, and polymeric carboxylic acid/citric acid.
Manufacture of Phenolic Resins
Alternative methods for manufacturing phenolic resins include enzymatic water-based polymerization processes (based on horseradish peroxidase and soy peroxidase) and pyrolysis of biomass.
- TURI has funded research into the control of hydrogen peroxide (an enzymatic inhibitor) in the horseradish peroxidase process.
- The soy peroxidase enzyme can be used to manufacture a variety of phenolic resins. These systems can result in decreased processing time and increased yield.
- The National Renewable Energy Laboratory of the U.S. Department of Energy has researched the use of pyrolysis (rapid heating in the absence of oxygen) of agricultural and forestry wastes to produce phenolic resins. This process is predicted to cost half as much as the current process.
Printed Wiring Boards
In the manufacture of printed wiring boards, it is necessary to make through-holes conductive. The most common process to accomplish this is the formaldehyde-containing electroless copper process. Formaldehyde acts as a reducing agent in the process.
- The U.S. EPA, through its Design for the Environment Printed Wiring Board Project, has evaluated the technical, environmental and financial performance of alternatives to the formaldehyde-containing electroless copper process. Carbon, graphite, organic-palladium, tin-palladium, electroless copper using sodium hypophosphite as the reducing agent, and conductive polymer technologies have been evaluated.
- Other potential alternatives include electroless nickel, conducting polymers like polypyrrole and non-formaldehyde-based electroless copper.
- Two formaldehyde-free electroless copper systems exist: the first of which uses hypophosphite as an alternative reducing agent to formaldehyde; the second is a catalytic process that uses a boron compound as an alternative reducing agent to formaldehyde
In many surface coating applications, alternatives to the formaldehyde-containing resins have been developed in an effort to comply with the Clean Air Act Amendments. These include water-based, ultraviolet-cured and electron beam-cured systems.
Sanitary Storage in Barbering/Cosmetology
The Massachusetts Board of Cosmetology currently requires that “dry sanitizer” be used in drawers where hair brushes are kept. This dry sanitizer is para-formaldehyde, a solid form of formaldehyde. The TURA program has been working with the Board to amend its regulations to eliminate this requirement.
Embalming and Tissue Preservation
Embalming is a mortuary custom of temporarily preserving bodies after death, generally by the use of chemical substances and most often in the U.S. and Canada by the use of solutions containing formaldehyde. Formaldehyde is also used to preserve biological specimens in middle and high school and university teaching and research laboratories.
- Respecting personal choice and religious custom, embalming may not be necessary depending on the funeral arrangements.
- Concern for mortuary workers’ exposures to formaldehyde has prompted research into alternative embalming chemicals. Ethyl alcohol/polyethylene glycol, glutaraldehyde and phenoxyethanol are alternatives to formaldehyde, although these may pose other worker health and safety concerns.
- One study funded by the U.S. EPA in the Burlington, Mass. public school system found that formaldehyde in science laboratories may have routinely exceeded permissible exposure limits and that the laboratories lacked sufficient ventilation. Less toxic alternatives are readily available from scientific supply vendors. Alternatives to formaldehyde preservation of specimens that best replicate the technical specifications of formaldehyde-preserved specimens for educational purposes include various formaldehyde-free solutions (e.g., propylene glycol, diazolidinyl urea and glutaraldehyde) and video/virtual dissection. Again, some of these alternatives have health and safety concerns, in particular glutaraldehyde, which is an asthmagen.
Traditionally, formaldehyde has been a component of the resins used in many building materials. As far back as the 1970s, the off-gassing of formaldehyde from these products, particularly foam insulation and medium density fiberboard, caused concern. During the last 30 years manufacturers have developed many “formaldehyde-free” and “low formaldehyde” products.
Building materials of interest include hardwood plywood (used for exterior building panels, and high-end interior applications such as bathroom and kitchen cabinetry) and structural panels.
- In 2009 TURI funded research into alternative resin systems as replacements for the formaldehyde-based phenolic resins commonly used in building products. This research investigated the use of epoxidized vegetable (soy, linseed and castor) oils as alternative feedstocks. Additional research and development would be necessary to create a viable alternative for specific building products.
- Pressed wood adhesive alternatives include those labeled “formaldehyde-free” or “low-emitting” or those made from phenol-formaldehyde (such as oriented strand board, softwood plywood or exterior grade plywood) generally emit lower levels of formaldehyde.
- Hardwood plywood and softwood plywood or oriented strand board can be manufactured using alternative adhesives, such as the soy-based resin developed for wood panel applications by Columbia Forest Products. Note that one of the resin feedstocks is epichlorohydrin, which is a probable human carcinogen that can result in negative impacts on respiratory and hematological systems.
- Composites of wood fiber and polypropylene thermoplastics are used extensively as substitutes for wood lumber, and are being developed for use in wood panel applications.
- Soybean protein modified with sodium dodecyl sulfate can also be used as an alternative resin for wood fiber medium density fiberboard preparation.
- Alternative building materials include those made from non-wood sources (e.g., recycled paper, wood fiber-Portland cement blend, rammed earth, metal, stone and brick) or solid wood. Agricultural fiber alternatives can come from crops grown specifically for fiber (e.g., kenaf and bagasse) and residues of crops grown for other purposes (e.g., corn stalks/cobs and cotton stalks).
- Global Insight. (2007). Socio-Economic Benefits of Formaldehyde to the European Union (EU 25) and Norway. Available at http://www.formaldehyde-europe.org/fileadmin/formaldehyde/PDF/Socio-Economic-Benefits-Study.pdf;
- Patent Storm, Non-formaldehyde Durable Press Finishing for Cellulosic Textiles with Phosphinocarboxylic Acid. Available at http://www.patentstorm.us/patents/5496477/fulltext.html;
- Yang, C. Q., and Chen, D. 233rd ACS National Meeting, Chicago, IL, United States, March 25-29, 2007;
- Alpert, A (2004), “Milady’s Standard: Cosmetology”, Milady Publishing Company, Clifton Park, NY;
- National Safety Council Environmental Health Center, “Formaldehyde,” (Washington, D. C.: National Safety Council: http://www.nsc.org/EHC/indoor/formald.htm; U.S. EPA, 1998, “Alternative Technologies for Making Holes Conductive: Cleaner Technologies for Printed Wiring Board Manufacturers,” EPA/744-R-98- 002, (Washington, D.C.: U.S. EPA: http://www.epa.gov/oppt/dfe/pubs/ pwb/pdf/ctsawire.pdf);
- Printed Wiring Board Resource Center “Electroless Copper Alternatives” accessed at www.pwbrc.org/bmr/ecalt.htm;
- Massachusetts Toxics Use Reduction Institute (MA TURI), “Formaldehyde Use Reduction in Mortuaries,” 1994, (Lowell, MA: TURI);
- U.S. EPA, “A Case Study of Environmental, Health and Safety Issues Involving the Burlington, Massachusetts Public School System: Formaldehyde,” (Washington, D.C.: U.S. EPA – see webpage: http://www.epa.gov/ region07/kids/;
- Institute for Local Self- Reliance, 1992, “The Carbohydrate Economy,” (Washington, D.C.: Institute for Local Self-Reliance; JER Envirotech Ltd – see webpage: http://www.jerenvirotech.com/032006/ files/en/asp/products/wpc.asp;
- Wei, Weishu and Charles Yang, 2000 “Polymeric Carboxylic Acid and Citric Acid as a Nonformaldehyde DP Finish,” Textile Chemist and Colorist, (Research Triangle Park, NC: American Association of Textile Chemists and Colorists) Vol. 32, No. 2, February 2000.
- University Research in Sustainable Technologies program of the Toxic Use Reduction Institute – see webpage: http://www.turi.org/ industry/research/ university_research_in_sustainable_technologies to learn more;
- Toxics Use Reduction Institute “Five Chemicals Alternatives Assessment Study” 2006 – see webpage: http://www.turi.org/industry/ research/five_chemicals_study;
- Li,Xin et al (2009). “Mechanical and water soaking properties of medium density fiberboard with wood finer and soybean protein adhesive” Bioresource Technology, 100:3556-3562.