| abstract |
The invention relates to a process for the production of highly concentrated and, surprisingly, viscosity-stable solutions of segmented polyurethane urea elastomers in highly polar solvents, such as dimethyl formamide and dimethyl acetamide, having little or no tendency to turn to paste, characterized by the use of certain primary and secondary cycloaliphatic monoamines or cycloaliphatic monisocyanates as chain-extending agents/blocking agents in the reaction of NCO prepolymers based on relatively high molecular weight dihydroxy compounds and (preferably aromatic) diisocyanates with aliphatic and and/or cycloaliphatic diamine chain-extending agents. The chain terminators according to the invention also show unexpected iprovements in the color of the elastomer solution and also in the stability of the end products, preferably filaments, to light and noxious gases. The invention also relates to elastomers of corresponding composition containing special terminators, preferably in the form of filaments, films or coatings showing improved stability to light and waste gases. |