To obtain improved thermoplastic polyurethane elastomers by mixing an isocyanate, a compound having Zerewitinoff active hydrogen atoms and a chain extender at a specific shear rate and then, reacting the mixture at a specific shear rate.
(A) An isocyanate, (B1) 0-85 equivalent % [based on (A)] compound having, on average, 1.8-3 Zerewitinoff active hydrogen atoms and a number average molecular weight of 400-10,000, (B2) 15-100 equivalent % chain extender having an average of 1.8-3 Zerewitinoff active hydrogen atoms and a molecular weight of 62-400, and (C) a practical amount of at most 20% auxiliary additive are charged in a first static mixer and uniformly mixed at a temp. of 50-250°C at a shear rate of 500-50,000 sec-1 to prepare an unreacted mixture. Then, this mixture is reacted in a second statistic mixer at a temp. of 50-250°C at a shear rate of 1-100 sec-1 to produce a thermoplastic polyurethane elastomer. By this method polyurethane elastomers uniform in improved properties can be obtained.
HANSUUPEETAA MIYURAA
MARUTEIN URURIHI
URURIHI RIIZENFUERUDAA
