Patent Number: 6,310,156

Title: (Meth) acrylic acid polymer and manufacturing method thereof

Abstract: A (meth)acrylic acid polymer is obtained by conducting a polymerization reaction using 60 mol % or more of a hydrophilic monomer containing (meth)acrylic acid and a combination of at least one kind of persulfate salts and at least one kind of bisulfite salts as an initiator series under conditions that a pH is smaller than 5 and a degree of neutralization is smaller than 40 mol %, in such a manner that a solid concentration when the polymerization reaction ends is 40% or higher. The resulting polymer has a weight average molecular weight ranging from 3,000 to 15,000, a sulfonic acid group at an end terminal, and an anti-gelling ability Q-value smaller than 2.0, where the anti-gelling ability Q-value is defined as: ##EQU1## Consequently, it has become possible to provide a low-molecular-weight (meth)acrylic acid polymer having not only excellent dispersing ability and chleating ability, but also high resistance to gelling, and an efficient manufacturing method of such a polymer.

Inventors: Maeda; Yoshihiro (Ibaraki, JP), Ishida; Tamao (Osaka, JP), Yamaguchi; Shigeru (Yao, JP)

Assignee: Nippon Shokubai Co., Ltd.

International Classification: C08F 20/00 (20060101); C08F 20/06 (20060101); C11D 3/37 (20060101); C08F 002/00 ()

Expiration Date: 10/30/2018