Patent ID: 7232873

Claim:
A polycarboxylic acid cement dispersant which provides a cement composition having a penetrating resistance value exponent of 55 MPa or more and a slump retention exponent of 80% or more, wherein the polycarboxylic acid cement dispersant comprises a polycarboxylic acid polymer having a polyoxyalkylene ester constituent unit (I) represented by the following general formula (1): wherein R 1 O may be the sane or different and each represents an oxyalkylene group containing 2 to 18 carbon atoms; m 1 represents the average molar number of addition of to oxyalkylene groups and is a number of 100 to 200; and R 2 represents a hydrogen atom or a hydrocarbon group containing 1 to 3 atoms, and a carboxylic acid constituent unit (II) represented byte following general formula (2): wherein R 3 represents a hydrogen atom, a methyl group or —COOM 2 ; and M 1 and M 2 may be to same or different and each represents a hydrogen atom, a monovalent metal, a divalent metal, ammonium or organic ammonium, wherein the polycarboxylic acid cement dispersant is obtained by copolymerizing the monomer components further comprising a sulfonic acid group-containing monomer represented by the following general formula (5): wherein R 12 and R 13 may be the same or different and each represents a hydrogen atom or a methyl group; Y and Z represent a hydroxyl group or —SO 3 M 9 , wherein in the case when Y represents a hydroxyl group, Z represents —SO 3 M 9 , while in the case when Y represents —SO 3 M 9 , Z represents a hydroxyl group; R 14 represents an alkylene group containing 2 to 4 carbon atoms; and M 6 , 7 , M 8 and M 9 may be the same or different and each represents a hydrogen atom, a monovalent metal, a divalent metal, ammonium or organic ammonium.