Patent ID: 7030177

Claim:
A method of dispersing a hydraulic composition, said method comprising adding a powdery dispersant to the hydraulic composition; wherein said powdery dispersant comprises at least one copolymer as a powder, wherein said copolymer is made by polymerizing at least one vinyl monomer (a) represented by the formula (1): wherein R 1 and R 2 represent a hydrogen atom or a methyl group, R 3 represents a hydrogen atom or —COO(AO) n X, m is a number of 0 to 2, p is a number of 0 or 1, AO represents a C 2-4 oxyalkylene group or an oxystyrene group, n is the average mole number of AO groups and is a number of 2 to 300, and X represents a hydrogen atom or a C 1-18 alkyl group; with at least one vinyl monomer (b) represented by the formula (2): wherein R 4 , R 5 and R 6 are the same as or different from one another and each represent a hydrogen atom, a methyl group or —(CH 2 ) m1 COOM 2 wherein —(CH 2 ) m1 COOM 2 is optionally combined with —COOM 1 or another —(CH 2 ) m1 COOM 2 to produce an anhydride so that M 1 and M 2 of these groups are not present, each of M 1 and M 2 represents a hydrogen atom or a monovalent metal, and m 1 is a number of 0 to 2, wherein the average mole number of C 2-4 oxyalkylene groups or oxystyrene groups of said copolymer is 50 to 150; (a)/[(a)+(b)]×100 ranges from 15 to 45 (mole %); at least part of the copolymer is a monovalent metal salt; and a degree of neutralization of 50% to 90%.