| 摘要 |
PROBLEM TO BE SOLVED: To provide the inhibitor which is capable of continuously and efficiently inhibiting calcium oxalate scale from being formed in a paper pulp production process and has good biodegradability by preparing an inhibitor containing as an active ingredient, a polyepoxysuccinic acid derivative obtained by reacting a hydroxycarboxylic acid with epoxysuccinic acid in a prescribed molar ratio of the hydroxycarboxylic acid to epoxysuccinic acid. SOLUTION: This inhibitor for inhibiting formation of calcium oxalate scale in a paper pulp production process, contains as an active ingredient, a polyepoxysuccinic acid derivative obtained by reacting a hydroxycarboxylic acid with epoxysuccinic acid in a molar ratio of the hydroxycarboxylic acid to epoxysuccinic acid of 1:3 to 1:30. As this hydroxycarboxylic acid used as one of the raw materials for preparation of the polyepoxysuccinic acid derivative, tartaric acid, malic acid, citric acid, lactic acid, gluconic acid, or the like, can be used. Epoxysuccinic acid used as the other raw material for preparation of the polyepoxysuccinic acid derivative, is prepared by a well-known method. In the preparation of such a polyepoxysuccinic acid derivative, when the molar ratio of epoxysuccinic acid is lower than the above range, the scale inhibitory effect of the resulting polyepoxysuccinic acid derivative is drastically reduced and when the molar ratio of epoxysuccinic acid is higher than the above range, and also if a calcium compound is used as a catalyst, separation of an insoluble calcium precipitate is sometimes caused.
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