Patent ID: 7241915

Claim:
A process for inhibition of polymerization of a (meth)acrylate ester where (meth)acrylic acid is used as a raw material, and in which: an N-oxyl compound and at least one member selected from the group consisting of manganese salt compounds, copper salt compounds, 2,2,6,6-tetramethylpiperidine compounds, and nitroso compounds are used together as polymerization inhibitors, and further at least one acid selected from the group consisting off a carboxylic acid and a carboxylic anhydride is added to any place of all the steps of the production process for the (meth)acrylate ester, wherein the carboxylic acid or carboxylic anhydride is at least one member selected from the group consisting of oxalic acid, oxalic anhydride, malonic acid, succinic acid, succinic anhydride, fumaric acid, maleic acid, maleic anhydride, octanoic acid, adipic acid, sebacic acid, tetradecanedicarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,3,6-hexanetricarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-pentanetetracarboxylic acid, 1,6,7,12 -dodecanetetracarboxylic acid, benzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, pyromellitic acid, pyromellitic anhydride, 1,2,4-benzenetricarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 1,3,5,7-naphthalenetetracarboxylic acid, salicylic acid, and acetic acid.