| 摘要 |
PROBLEM TO BE SOLVED: To provide a copolymer for an excellent cement additive exhibiting high water-reducing performance. SOLUTION: This copolymer (A) consists of a polyalkylene glycol 3-methyl-3- butenyl ether monomer (I) having a number average mol.wt. of 1,800 to <2,800 (expressed in terms of polyethylene glycol) by gel permeation chromatography, a maleic acid type monomer (II) and another monomer (III) copolymerizable with the monomers (I) and (II) and has a 65-90 mgKOH/g carboxylic acid value and a 18-26 mgKOH/g hydroxyl value. The copolymer (A) is used for a cement additive.
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