PURPOSE: To exhibit sufficient polymerization inhibiting effect in a small amount even in steps in which a (meth)acrylic acid ester is readily polymerizable by combinedly using a p-phenylene-diamine compound, a phenol compound and phenothiazine.
CONSTITUTION: This polymerization inhibitor composition is obtained by combining a p-phenylenediamine compound of the formula (R1 and R2 are each a 1-8C alkyl, phenyl or a 1-4C alkyl groupsubstituted phenyl), a phenol compound and a phenothiazine. N,N-Diphenyl-p-phenylenediamine, etc., is preferably used as the p-phenylenediamine compound. Hydroquinone, metoquinone, etc., is preferably used as the phenol compound. A blend weight ratio of these three compounds is preferably 1:(0.3 to 3):(0.3-3). The distillation is carried out in the presence of the polymerization inhibitor composition and oxygen when (meth)acrylic acid is distilled to inhibit polymerization of (meth)acrylic acid ester.
KAMIMURA MASAHIRO
TAKEDA TAKAHIRO
KAMIOKA MASATOSHI
