| 摘要 |
1276447 Polyurethanes FARBENFABRIKEN BAYER AG 10 April 1970 [11 April 1969] 17121/70 Headings C3P and C3R [Also in Division C2] A linear segmented polyurethane elastomer is obtained by the reaction between an isocyanate pre-adduct containing 1À0 to 6À0% by weight of free isocyanate groups, and a chain lengthening agent of the formula H 2 NNHCONH-R-OCONHNH 2 , such that the elastomer contains at least 55 mol. per cent (based on the total amount of chainlengthening segments) of a chain-lengthening segment of the structure where R is a C 2-4 alkylene radical or a divalent cycloaliphatic, aromatic, araliphatic or alaromatic radical. The elastomer may also contain up to 45% of intralinear segments which are formed by reaction of the isocyanate groups with other chain lengtheners, e.g. water, aminoalcohols or compounds having two terminal -NH 2 groups, such as compounds of the formula H 2 N-Z-NH 2 , Z being a direct bond or a divalent organic radical without substituents which react with isocyanates. In the production of the isocyanate preadducts, high molecular weight polyhydroxy compounds may be used optionally together with small quantities of lower molecular weight dehydroxy compounds. Examples illustrate the use of chain-lengthening agents in which R is an ethylene, propylene or tolylene radical. |
