Process for the production of matte, non-blocking, thin-walled molded articles from linear thermoplastic polyurethane elasotomers containing polyadducts and their use

Claim 1

A process for the production of a matte, non-blocking, thin-walled molded article, film or tube from a polyurethane elastomer based on (A) a dispersion comprising (Ab) a relatively high molecular weight, high melting polyisocyanate polyaddition product dispersed in (Aa) a relatively high molecular weight, polyfunctional compound containing isocyanate reactive groups with Zerewitinoff-active hydrogen atoms and having a molecular weight of 400 to about 10,000 and a melting point below 60° C., (B) a chain lengthening agent with a molecular weight of 18 to 399 containing two Zerewitinoff-active hydrogen atoms and (C) a diisocyanate, wherein (I) said polyurethane elastomer is thermoplastically processible, has a substantially linear structure and is prepared at a molar ratio of isocyanate groups to the sum of all of the groups containing Zerewitinoff-active hydrogen atoms of about 0.95 to 1.05, (II) component (Ab) comprises a high melting polyisocyanate polyaddition product based on (α) a low molecular compound having a molecular weight of 18 to 399 and containing at least two Zerewitinoff-active hydrogen atoms and (β) an organic di- and/or polyisocyanate in a molar ratio of isocyanate groups to isocyanate reactive groups having Zerewitinoff-active hydrogen atoms of about 0.8:1 to 1.3:1, contained in the relatively high molecular weight, bifunctional compound (Aa) in the form of a finely divided dispersion having an average particle size of about 0.01 to 25 μm, the dispersed polyaddition product (Ab) having a melting point above about 220° C., and its dispersion in component (Aa) being stable and remaining finely divided up to a temperature at least 15 degrees Centigrade higher than the processing temperature of the polyurethane elastomer without decomposing or dissolving, the polyadduct (Ab) being used in a quantity of about 0.66 to 15% by weight, based on the polyurethane elastomer containing the polyadduct, and (III) converting said polyurethane elastomer by an extrusion, film blowing or calendering process at a processing temperature above about 110° C. into a thin-walled, matte, molded article, film or tube having a wall thickness below about 2 mm, in which the polyadduct (Ab) is finely divided and homogeneously distributed within the thin-walled molded article.