(Meth) acrylic copolymer and its production process

摘要

There are disclosed a (meth)acrylic copolymer and its production process, wherein the (meth)acrylic copolymer has the good chelating ability and dispersibility and is excellent both in the calcium-ion-binding ability and the gelation resistance in combination, and further, the deterioration of these various performances is inhibited even in the water system of high salt concentration. The (meth)acrylic copolymer comprises a constitutional unit (a) derivative from a specific (meth)acrylic monomer (A) and a constitutional unit (b1) derivative from a specific (meth)allyl-etheric monomer (B1) and has a phosphorus atom in the main chain; with the (meth)acrylic copolymer being characterized by having: a mutual ratio between the constitutional unit (a) and the constitutional unit (b1) in the specific range; a low molecular weight; and a content of phosphorus, as bonded to the copolymer, in the predetermined range; and further a gelation resistance of not more than 0.02 and a calcium-ion-binding ability of not less than 150 mgCaCO3/g.