Abstract: The invention relates to a process for the production of low-gel spinning solutions-surprisingly stable in their solution viscosity-of segmented polyurethane urea elastomers in highly polar solvents, such as dimethyl formamide or dimethyl acetamide, characterized by the use of multistage jet reactor, and to a multistage jet reactor.

Abstract: This invention relates to a process for the production of light resistant and exhaust gas resistant PUH elastomer threads and films based on segmented polyurethane ureas which are based on diisocyanate mixtures of from 30 to 85 mol% of trans-1,4-cyclohexylene diisocyanate and from 70 to 15 mol% of other aliphatic or cycloaliphatic diisocyanates. The diisocyanates are first reacted with relatively high molecular weight dihydroxy compounds and optionally low molecular weight diols to form an isocyanate prepolymer which is then reacted with aliphatic diamines or diamine mixtures, preferably ethylene diamine, in highly polar solvents, optionally in the presence of salt type solubilizing agents such as lithium salts and preferably with the aid of aliphatic chain terminators, in particular those having a cycloaliphatic structure, to produce elastomer solutions which are stable under processing conditions.

Abstract: A process for the production of highly elastic elastane fibers (spandex fibers) based on segmented polyurethane (urea) elastomers having high elasticity and, at the same time, high strength values, balanced elastic properties and excellent thermal and hydrothermal behavior, wherein relatively high molecular weight, carbonate-linked, block-like polyester of polyester etherdiols having molecular weight of 3,300 to 7,000 are reacted with macrodiols with diisocyanates in a molecular ratio of 1:2.5 to 1:4.5 to obtain NCO prepolymers which have NCO contents of 2.10 to 4.0% NCO, then the NCO prepolymer is chain-extended with (cyclo)-aliphatic diamines to fom polyurethane (urea) elastomers.

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.