Polymerization initiators unsaturated monomer and a curing agent for unsaturated polyester resin composition

摘要

PURPOSE:To provide the subject radical reaction initiator composed of a specific monoperoxycycloalkyl ketal, having high chemical stability and excellent decomposition characteristics at low temperature, causing little hydrogen abstraction reaction and giving a polymer having narrow molecular weight distribution. CONSTITUTION:The objective radical reaction initiator composed of a cyclic monoperoxy ketal of formula III can be produced by dripping a mixture of (A) a cyclohexanone dialkyl acetal of formula I (R1-R3 are H or 1-3C alkyl; R4 is 1-5C alkyl) and (B) an alkyl hydroperoxide of formula II (R5 is 1-3C alkyl; R6 is 1-3C alkyl; R7 is 1-8C alkyl, cycloalkyl, aryl, etc.) to (C) a mixture of dimethyl sulfoxide and p-toluenesulfonic acid, adding petroleum ether to the reaction mixture, washing with water, alkali, etc., and distilling out the solvent under reduced pressure.