Water-soluble polymer sensitive to salt

Abstract

A water-soluble polymer which is soluble in tap water, but insoluble in an aqueous solution containing 0.5% or more of a neutral inorganic salt, which is a copolymer of: (A) 30 to 75% by weight of acrylic acid, (B) 5 to 30% by weight of a vinyl monomer represented by the following general formula [1]: CH.sub.2 .dbd.C(R)COOR.sup.1 [1] wherein R represents a hydrogen atom or a methyl group; and R.sup.1 represents an alkyl group having 8 to 12 carbon atoms, and (C) 20 to 40% by weight of a vinyl monomer represented by the following general formula [2]: CH.sub.2 .dbd.C(R.sup.2)COOR.sup.3 [2] wherein R.sup.2 represents a hydrogen atom or a methyl group; and R.sup.3 represents an alkyl group having 2 to 4 carbon atoms and in which not more than 50 molar % of the repeating units of derived from the acrylic acid is in the form of a salt. When the polymer is used as a binder for a non-woven fabric or paper, it exhibits satisfactory strength and permeability to a body fluid when the resultant product is wet with body fluid.

Dependencies are inferred from the claim text.