Mitsubishi Kasei Corporation

Arakawa Kagaku Kogyo Kabushiki Kaisha

Masato Nakajima

Shigeru Sawayama

Atsushi Ikeda

Kenji Yokotani

The present invention relates to a method for sizing of paper by using a particular vinylamine polymer as a size-fixing aid. By the use of the vinylamine polymer as a size-fixing aid, it has become possible to obtain a paper having superior sizing properties by papermaking at a pH around neutrality using a hitherto known acidic sizing agents without using a neutral sizing agent. The method of the present invention further has effects that operating efficiency of papermaking is greatly improved since contaminations of a papermaking machine due to a neutral agent can be avoided, and therefore, the prices of paper can be greatly lowered. The present method has further advantages when it is applied under acidic papermaking condition of a pH of less than 5.5. In such a condition, the addition amount of alum can be decreased and the life of a papermaking machine can be prolonged. In spite of a small amount of alum added, a considerably good sizing effect can be obtained by the present method.

Method for sizing of paper

A method for making papers which comprises: using a paper sizing agent comprising as an effective component an .alpha.-hydroxycarboxylic acid having the formula (I): ##STR1## wherein R.sup.1 is an alkyl group having 8 to 30 carbon atoms, an alkenyl group having 8 to 30 carbon atoms, ##STR2## and R.sup.2 is hydrogen atom, or an alkyl or alkenyl group having 1 to 30 carbon atoms, or a salt thereof. The paper sizing agent used in the method can exhibit the excellent sizing effect in paper making under the condition of the wide pH-range from pH 3 to pH 9, and has an excellent storage stability. Further the method is excellent in workability and high in industrial value.

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Hirakata, Japan

Masato Nakajima