Patent ID: 7638563

Claim:
A polycarboxylic acid concrete admixture comprising a polycarboxylic acid polymer containing a polyalkylene glycol in the side chain, wherein said polycarboxylic acid polymer is formed by polymerizing monomer components comprising 22 to 55 mole % of at least one alkyl (meth)acrylate monomer selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate and butyl (meth)acrylate, 15 to 40 mole % of a polyalkylene glycol unsaturated monomer represented by the following formula (1); wherein R 1 , R 2 and R 3 may be the same or different and each represents a hydrogen atom or a methyl group; R 4 represents a hydrogen atom or a C1 to C20 saturated alkyl group or a C1 to C20 unsaturated alkyl group; R a may be the same or different and represents an alkylene group containing 2 to 18 carbon atoms; n represents an average molar number of addition of the oxyalkylene group represented by R a O and is a number of 2 to 25; X represents a divalent alkylene group containing 1 to 5 carbon atoms or represents that the carbon atom and oxygen atom bonded to X are directly bonded to each other in case of the group represented by R 1 R 3 C═CR 2 X— is a vinyl group, and X may be a —CO— bond, and 19 to 65 mole % of an unsaturated carboxylic acid (salt) monomer, and has a weight average molecular weight of 18000 or less.