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POLYURETHANE RAW MATERIALS FOR DIVERSE TEXTILE COATING AND COAGULATION APPLICATIONS
Coatings formulated with these products are characterized by, among other things, high abrasion resistance, flexibility, low-temperature flexibility and even water vapor permeability, if desired. Products which are lightfast and particularly resistant to hydrolysis can also be obtained. The product line for textile coatings comprises aliphatic and aromatic, one- and two-component polyurethane resins in the form of aqueous dispersions, solutions, high solids and granules. The two-component products may be crosslinked with resins or isocyanates, depending on their grade. Nearly all of the aqueous dispersions are completely solvent-free. Polyurethane solutions contain between 25 and 50 percent solids, whereas high solids systems are available with a solids content of up to 100 percent. Polyurethane leather is also in trend as a substitute for natural leather. It is used primarily as an upper material for shoes, bags and luggage, for automotive interiors and as a coating for ball surfaces, for example. The systems are suitable for use as a finish, topcoat, intermediate coat and an adhesion coat on textile substrates. The success of polyurethane leather is due in part to its economical production, but above all to its property profile which is nearly the equal of, and in some aspects superior to, that of natural leather. “Although it is now nearly impossible to distinguish the two materials, polyurethane leather has distinct advantages with respect to durability,” says Rolf Irnich, an expert for textile coating and coagulation at Bayer MaterialScience. Furthermore, individual properties can be specifically modified to suit the respective application, e.g. more comfortable automobile seats or good abrasion resistance in the case of the Roteiro™ soccer ball from adidas, the official match ball of the 2004 European Soccer Championship in Portugal. Its surface material is a high solids polyurethane coating formulated with products from Bayer MaterialScience’s Impranil® line of products and is characterized by very low water absorption. Beneath that is an elastic layer of Impranil®, a syntactic polyurethane foam with low-temperature flexibility which ensures good ball feel. Bayer MaterialScience offers raw materials for primarily three different polyurethane leather production processes. With the coagulation process, even, porous coating s are obtained by the precipitation of the polyurethane from solution. Primary applications here include shoe uppers, automotive interiors and specialty applications such as ball surfaces. In another manufacturing process, a high solids polyurethane system is applied, which then cures to form a foam layer. The solids content can be set very high – up to 100 percent. Solvent-free waterborne formulations based on the dispersion Impranil® VP LS 2384 yield foam layers that are insensitive to water and many organic solvents and also exhibit high lightfastness. These are ideally suited for the manufacture of furniture with synthetic leather coverings, for example. http://www.bayermaterialscience.com
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