A first object of the present invention is to provide a method for producing a carboxyl group-containing water-soluble polymer capable of giving neutralized viscous solutions excellent in thickening effect even when the aqueous solutions of the carboxyl group-containing water-soluble polymer have a low concentration. A second object of the invention is to provide a method for producing a carboxyl group-containing water-soluble polymer capable of giving neutralized viscous solutions excellent in thickening effect at low concentration levels and, at the same time, capable of being dispersed and dissolved in water at high concentrations with ease.
The prevent invention is a method for producing a carboxyl group-containing water-soluble polymer by reacting an α,β-unsaturated carboxylic acid and a compound having two or more ethylenically unsaturated groups in the presence of a radical polymerization initiator, which method is characterized in that the reaction is carried out in the presence of a (meth)acrylic acid derivative represented by the general formula (1):
(in the formula, R
1
and R
2
each independently represents a hydrogen atom or a methyl group and n represents 1 or 2).
本发明的第一目的是提供一种生产含羧基
水溶性聚合物的方法,即使羧基
水溶性聚合物的
水溶液浓度较低,也能产生优良的增稠效果。本发明的第二目的是提供一种生产含羧基
水溶性聚合物的方法,该方法能够在低浓度下产生优良的增稠效果,并且同时能够在高浓度下轻松分散和溶解于
水中。
该方法是通过在自由基聚合
引发剂存在下,使α,β-不饱和
羧酸和具有两个或更多
乙烯基不饱和基团的化合物反应而生产含羧基
水溶性聚合物的方法。该方法的特征在于,在一般式(1)所表示的(甲)
丙烯酸衍
生物的存在下进行反应:
(在该式中,R1和R2分别独立表示氢原子或甲基,n表示1或2)。