PROCESS FOR THE PREPARATION OF LIGHT AND EXHAUST GAS RESISTANT PUH ELASTOMER FIBRES AND FILMS AND THE ELASTOMER FIBRES WITH THE CORRESPONDING COMPOSITION

The invention relates to a process for the production of polyurethaneurea elastomer filaments and films which are resistant to light and to polluting gases and are based on segmented polyurethaneureas, based on diisocyanate mixtures of 30 to 85 mol % trans-1,4-cylcohexylene diisocyanate and 17 to 15 mol % of further aliphatic or cycloaliphatic diisocyanates. The diisocyanates are reacted with relatively high molecular weight dihydroxy compounds and optionally low molecular weight diols, initially to give an NCO prepolymer, and then with aliphatic diamines or diamine mixtures, preferably ethylenediamine, in highly polar solvents, optionally in the presence of salt-like solvents, such as lithium salts, and preferably with the concomitant use of aliphatic chain terminators, in particular those having a cycloaliphatic structure, to give elastomer solutions which are stable to processing. These solutions are spun in a conventional manner and dried to give films or coagulated to give sheets. The invention also relates to the segmented polyurethaneurea elastomers, in particular filaments, obtained by the novel process.