PREPOLYMERS OF POLYVINYL ALCOHOL, POLYMERS OBTAINED BY PHOTOCROSSLINKING SAID PREPOLYMERS, PROCESSES FOR PREPARING SAID POLYMERS FROM SAID PREPOLYMERS AND MOULDINGS THEREOF

摘要

A prepolymer which is a derivative of a polyvinyl alcohol having a molecular weight of at least 2000 that, based on the number of hydroxy groups of the polyvinyl alcohol, comprises from 0.5 to 80% of units of the formula wherein R is lower alkylene, R1 is hydrogen or lower alkyl, p is zero or one, q is zero or one, R3 is an olefinically unsaturated coplymerisable radical having from 2 to 8 carbon atoms and R4 and R5 are each independently lower alkylene having from 2 to 8 carbon atoms, arylene having from 6 to 12 carbon atoms, a saturated divalent cycloaliphatic group having from 6 to 10 carbon atoms, arylenealkylene or alkylenearylene having from 7 to 14 carbon atoms or arylenealkylenearylene having from 13 to 16 carbon atoms. 134 כ" ד באדר התשס" א - March 19, 2001