Low-emission PU hotmelt adhesive reduces hazards for workers

By Liz White, UT staffDüsseldorf, Germany-German adhesives major Henkel KgaA has developed a new polyurethane hot-melt adhesive-Purmelt MicroEmission-that releases up to 90 percent less isocyanate vapour than previous types. Henkel has applied for five patents for this new range, which it claims "represents a major step forward for the health and safety of employees that work with hotmelt adhesives." Independent testing has resulted in the adhesive range being recommended by the German statutory insurance body for the printing and paper processing industry, said a Henkel statement. Hotmelt adhesives are heated to 170°C during bonding, which, in existing polyurethane types, result in emission of monomeric isocyanate vapours. Workers must wear personal protective equipment and work under vapour extraction units to stop them breathing the fumes. Since use of Purmelt MicroEmission cuts isocyanate-containing vapour by up to 90 per cent, under EU law it does not require a hazard label, Henkel said. Polyurethane hotmelts have many advantages over other adhesives systems," according Henkel's polyurethane expert Dr. Michael Krebs, quoted in the statement. These include freedom from solvents, instantaneous adhesion, high structural strength and excellent resistance to ageing. When we started developing this new generation of polyurethane hotmelts, we asked if we took a fresh approach in this field."The Fraunhofer Institute for Manufacturing Technology and Applied Materials Research in Bremen (IFAM), and the statutory accident insurance institution for the printing and paper processing industry in Germany have closely examined Henkel's results. Specifically they measured emissions, using a bookbinding machine, from a point right at the glue applicator. They were unable to measure any isocyanates down to the method's limit-less than a tenth of the permitted workplace limit of 0.05 mg/cu.m. Hotmelt adhesives-widely used in, for example, building the walls of mobile homes, making furniture profiles, and brochure binding-are subject to hazard labelling under EU law, but the reduced isocyanate vapours mean Purmelt products do not need such labelling. An Italian furniture manufacturer is among the many users that have switched to the low-isocyanate Henkel product. This move indicates its long-term commitment to occupational health and environmental protection to its key account, a leading Scandinavian furniture store chain. …our customer is not only improving working conditions for his own employees, but has also gained a major competitive edge in his bid to serve this major customer," said Volker Mansfeld, marketing manager in Henkel's general industry unit. "