| 摘要 |
<p>1481574 Transfer coating with polyurethanes BAYER AG 22 Jan 1975 [22 Jan 1974] 2777/ 75 Heading B2E [Also in Divisions B5 and C3] A process for coating a textile sheet with a polyurethane by a transfer coating process in which, in a first stage, a solution of a polyurethane which is substantially free from reactive end groups is applied as top coat to a release substrate and the top coat is dried and, in a second stage, a bonding coat solution is applied to the top coat, the textile sheet is backed onto it, the solvent on the bonding coat is evaporated off on a second drying operation and the coated textile is then lifted from the release substrate, in which process the top coat is used as a polyurethane which has been prepared by reacting (a) at least one dihydroxy compound e.g. a dihydroxypolyether or a dihydroxypolyester, with a molecular weight of between 600 and 4000, (b) at least one diisocyanate and (c) a mixture of two diols each with a molecular weight between 62 and 450, at least two of which diols are each present in a quantity of more than 5 mole %, based on the mixture of diols, the molar ratio of the compounds (a) and (c) being between 1:1 and 1:5. Many suitable reactants for forming the polyurethane are listed. The bonding coat may be identical with the top coat; alternatively, a polyurethane made with the aid of a single diol or a two-component polyurethane system may be used. The release material may be a release paper.</p> |
