| 摘要 |
The present invention relates to a sizing agent which exerts excellent sizing efficiency even under severe conditions, namely, at an elevated temperature in the papermaking step, or at high conditions with a limited aluminum sulfate addition. The sizing agent for paper of the present invention is derived from i) dehydration condensation of an alkenylsuccinic anhydride and an organic carboxylic acid with a polyalkylene polyamine and ii) saponification of the remaining carboxyl groups with alkali following the dehydration condensation. More particularly, the present invention relates to a water-soluble sizing agent which is obtained by mixing an alkenylsuccinic anhydride with 1 to 20 times by molar equivalent, based on said alkenylsuccinic anhydride, as much as an organic carboxylic acid, adding 0.1 to 2.0 times by molar equivalent, based on said alkenylsuccinic anhydride, as much as a polyalkylene polyamine thereto so as to perform dehydration condensation. An then, to make the reacted material soluble to water, the remaining carboxyl groups are saponified with an alkali in an amount almost corresponding to the saponification equivalent.
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