To obtain a scale preventive agent capable of preventing adhesion of scale by effectively suppressing deposition of scale crystals such as calcium salt in water and the crystal growth, especially capable of preventing deposition and adhesion of scale of a high concentration of calcium ions which can not effectively be prevented by conventional polymaleic acid only.
The scale preventive agent contains 0.0001-5 pts.wt. of an alkali metal salt of a 1, 2-dicarboxylic acid based on 100 pts.wt. of the polymaleic acid. Preferably, the scale preventive agent contains 0.0001-5 pts.wt. of a polymer alkali metal salt containing a 1, 2-dicarboxylic acid unit in its structural unit based on 100 pts.wt. of the polymaleic acid. Furthermore, in the scale preventive agent, the polymaleic acid is obtained by heating a mixture comprising maleic anhydride, an aromatic solvent, and a polymerization initiator to obtain a polymer, and hydrolyzing the polymer.
TASHIRO TETSUO
IMAEDA TAKASHI
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