Method for producing polycarboxylic acid copolymer and copolymer composition for cement admixture

摘要

The present application relates to a production method for a polycarboxylic acid-based copolymer including a structural unit (I) derived from an unsaturated polyalkylene glycol ether-based monomer (a) and a structural unit (II) derived from an unsaturated carboxylic acid-based monomer (b), in which monomer components including the monomer (a) and the monomer (b) are polymerized using a peroxide and a reductant as polymerization initiators in combination while the pH during polymerization is controlled to 3 or less in the presence of a pH adjustor. The present application also relates to a polycarboxylic acid-based copolymer for a high-performance cement admixture including a structural unit (I) derived from an unsaturated polyalkylene glycol ether-based monomer (a) and a structural unit (II) derived from an unsaturated carboxylic acid-based monomer (b), and a nonpolymerizable organic sulfonic acid having a molecular weight of 300 or less and/or a salt thereof.

主权项

1. A production method for a polycarboxylic acid-based copolymer comprising:
polymerizing monomer components including an unsaturated polyalkene glycol ether based monomer (a) and an unsaturated monocarboxylic acid-based monomer (b) using a peroxide and a reductant as polymerization initiators in combination while a pH during polymerization is controlled to 3 or less in a presence of a pH adjustor; monomer (a) being represented by the general formula (1): [Chem 1]
YO(TO)m(R1O)nR2  (1) where: Y represents a 3-methyl-3-butenyl group; T represents an alkylene group having 1 to 5 carbon atoms or an aryl group having 6 to 9 carbon atoms; R1O represents one kind or two or more kinds of oxyalkylene groups having 2 to 18 carbon atoms; m represents 0 or 1; n represents an average addition mole number of the oxyalkylene groups and n represents 1 to 500;and R2 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and monomer (b) represented by the general formula (2): where: R3, R4, and R5 are identical to or different from each other and each represent a hydrogen atom, or a methyl group; and M represents a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group, or an organic amine group wherein the carboxylic acid-based copolymer comprises a structural unit (I) derived from monomer (a) and a structural unit (II) derived from monomer (b); and wherein the polycarboxylic acid-based copolymer does not include a structural unit derived from an unsaturated dicarboxylic acid-based monomer.