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LOW-EMISSIONS AND ECONOMICAL BONDING
The demands of both consumers and legislators can be met by adhesives formulated with waterborne Dispercoll® dispersions from Bayer MaterialScience. Bond quality matches the high level of solventborne systems. The conversion to waterborne adhesives in industry does not have to mean less economical bonding processes, either. “One-component adhesives based on waterborne polychloroprene (CR) dispersions from the Dispercoll® C range have proven themselves in the foam bonding industry, for example, and are increasingly used with great success in the manufacture of upholstered furniture and mattresses,” reports Dr. Mathias Matner, an expert for polychloroprene adhesive raw materials at Bayer MaterialScience. But the construction, automobile and shoe industries also appreciate environment-friendly adhesives containing Dispercoll® C for their long contact adhesion times, good adhesion and the resistance of the bond to moisture, greases and oils. The high green strength of waterborne adhesives formulated with Dispercoll® C can be significantly increased using Dispercoll® S silica gel dispersions. Such adhesives represent an economic advantage for industrial users because they allow them to quickly begin further processing of their products after joining. The use of Dispercoll® S also results in significantly improved heat stability, especially in adhesives formulated with CR products with a high hydroxyl content such as Dispercoll® C XP 2325. A pleasant side effect of the 10 to 55 nanometer particles of Dispercoll® S is the ability to adjust the rheology of the adhesive over a wide range. Bayer MaterialScience has also developed environment-friendly alternatives to solventborne, heat-activated adhesives. “The waterborne polyurethane dispersions in our Dispercoll® line of products can be used to formulate adhesives which will allow the shoe industry, for example, to meet the future requirements of the VOC directives,” says Wolfgang Arndt, an expert on polyurethane adhesives at Bayer MaterialScience. In the shoe industry – which throughout the world still uses primarily solventborne CR and polyurethane adhesives – the conversion to waterborne systems is especially desirable from an ecological standpoint, as solvent recovery is often impossible and optimal extraction of the volatile organic compounds from work areas is not always possible. Comprehensive comparison tests of polyurethane dispersion adhesives and their solventborne equivalents show that the waterborne systems based on Dispercoll® S meet or even exceed today’s high quality standard for the bonding of shoe soles, for example. Tests in which typical shoe sole materials such as rubber, PVC and ethylene vinyl acetate were bonded to various types of leather revealed no differences. In each case, the material failed, not the bond. Furthermore, detailed profitability studies show that the costs of waterborne systems are on the same scale as those of solventborne adhesives if one correctly compares the cost of adhesive per pair of shoes and not the cost per kilogram. http://www.bayermaterialscience.com
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