Process for the production of elastomeric polyurethane ureas

Abstract

Abstract 1508317 Elastomeric polyurethane ureas BAYER AG 13 May 1975 [16 May 1974] 20082/75 Heading C3R Elastomeric polyurethane ureas are prepared by reacting a diisocyanate a polyhydroxyl compound of M.W. from 500 to 10,000 and an aliphatic, cycloaliphatic and/or araliphatic primary and/or secondary diamine or hydrazine or acid hydrazide in a self-cleaning two-shaft screw extruder with both the shafts rotating in the same sense at a temperature of 110‹ to 280‹ C. and at a viscosity range during the reaction in the extruder of 0À1 to 3000 poises, such that, when the reaction mixture is very sticky and has a viscosity of 100 to 1000 poises, is is passed through a zone of the screw which is situated near to the inlet zone for the reaction mixture and which contains vigorously mixing kneading elements with kneading frequencies of 1 to 20 Hertz and in which there is a velocity gradient in the radial clearance between the screw comb and housing wall of more than 2000 sec.<-1>. It is preferred to form a prepolymer from the diisocyanate and polyhydroxy compound and to feed this prepolymer and the diamine separately to the extruder. The kneading elements preferably comprise a series of prismatic discs of various geometrical shapes. After the critical kneading step, the reaction mixture may be subjected to further kneading steps before forming thereof. In a typical example, a linear polyester is reacted with 1- isocyanato - 3 - isocyanatomethyl - 3,5,5 - trimethyl cyclohexane to form a prepolymer which is reacted in an extruder with 1-amino-3- aminomethyl-3,5,5-trimethyl cyclohexane.

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