1. Field of the Invention
This invention relates to polyurethane ureas, to a process for their production and to a process for the reactive coating of substrates, particularly sheet-form materials of fabric or leather, using the polyurethane ureas.
2. Description of the Prior Art
The reactive coating of substrates with polyurethanes is known per se; the starting products, optionally dissolved in a suitable solvent, are applied to the substrate, preferably by means of a spray gun.
In the prior art, prepolymers containing isocyanate groups and selected polyamines, for example reactive, aromatic or sterically hindered polyamines, are intensively mixed. The resulting mixture is either directly sprayed onto the substrate to be coated or, preferably, onto a temporary support and the substrate to be coated, for example leather, paper, nonwovens or fabrics in web form, is subsequently laminated on. The coated material is transported through a drying tunnel for further reaction of the coating. The substantially reacted material is then removed from the temporary support. This prior art is represented, for example, by DE-OS No. 1,570,524 (U.S. Pat. No. 3,475,266), DE-AS No. 2,637,115 (U.S. Pat. No. 4,108,842) and DE-OS No. 2,826,232 and by the literature cited therein.