(METH) ACRYLIC ACID-BASED COPOLYMER, METHOD FOR PRODUCING THE SAME AND DETERGENT COMPOSITION USING THE SAME

The present invention provides a (meth)acrylic acid-based copolymer useful to a detergent which is excellent in efficient removal capability of soil of clothes (in particular, hydrophobic soil such as collar dirt or greasy dirt), and prevention capability of soil redeposition, not to re-adhere the soil to laundries, even in carrying out washing with small amount of water. The present invention provides a (meth)acrylic acid-based copolymer comprising, as repeating units: a repeating unit (a) derived from a (meth)acrylic acid-based monomer (A) represented by the formula (1); and a repeating unit (b) derived from an alkyl(meth)acrylate-based monomer (B) represented by the formula (2) or a repeating unit (c) derived from a vinyl aromatic-based monomer (C); and 1 or, 2 or more kinds of repeating units (d) selected from the group consisting of a repeating unit (d-1) derived from an unsaturated monomer (D-1) represented by the formula (3), a repeating unit (d-2) derived from an unsaturated monomer (D-2) represented by the formula (4) a repeating unit (d-3) derived from a hydroxyalkyl(meth)acrylate-based monomer (D-3) represented by the formula (5), and a repeating unit (d-4) derived from a sulfonic acid group containing monomer (D-4) represented by the formula (6). Furthermore, the present invention provides a method for producing said (meth)acrylic acid-based copolymer.