A modified PVA that enables formation of a film superior in cold water solubility, mechanical strength, and chemical resistance is provided. The modified PVA comprises a monomer unit represented by formula (I), and a structural unit represented by formula (II): ##STR00001##
wherein: a content of the monomer unit (I) is from 0.05 mol % to 10 mol %, and a content of the structural unit (II) is from 0.001 mol % to 0.5 mol % with respect to the total monomer units in the modified PVA; a viscosity average degree of polymerization is from 300 to 3,000; and a degree of saponification is from 82 mol % to 99.5 mol %. In the formula (I): R.sup.1 represents a hydrogen atom, or a methyl group; and R.sup.2 represents R.sup.3SO.sub.3.sup.X.sup.+, R.sup.3N.sup.+(R.sup.4).sub.3Cl.sup., or a hydrogen atom, R.sup.3 representing an alkanediyl group, X.sup.+ representing a hydrogen atom, a metal atom, or an ammonium group, and R.sup.4 representing an alkyl group.

A modified PVA that enables formation of a film superior in cold water solubility, mechanical strength, and chemical resistance is provided. The modified PVA comprises a monomer unit represented by formula (I), and a structural unit represented by formula (II): ##STR00001##
wherein: a content of the monomer unit (I) is from 0.05 mol % to 10 mol %, and a content of the structural unit (II) is from 0.001 mol % to 0.5 mol % with respect to the total monomer units in the modified PVA; a viscosity average degree of polymerization is from 300 to 3,000; and a degree of saponification is from 82 mol % to 99.5 mol %. In the formula (I): R.sup.1 represents a hydrogen atom, or a methyl group; and R.sup.2 represents R.sup.3SO.sub.3.sup.X.sup.+, R.sup.3N.sup.+(R.sup.4).sub.3Cl.sup., or a hydrogen atom, R.sup.3 representing an alkanediyl group, X.sup.+ representing a hydrogen atom, a metal atom, or an ammonium group, and R.sup.4 representing an alkyl group.

An object of the present invention is to provide a dispersion stabilizer for suspension polymerization which satisfies various performance requirements for suspension polymerization of a vinyl-based compound such as vinyl chloride. The present invention relates a modified vinyl alcohol-based polymer having at least one monomer unit represented by a following general formula (I) and a modification rate of from 0.01 mol % to 10 mol %:

general formula (1):

##STR00001##

in which BO represents an oxybutylene unit; EO represents an oxyethylene unit; and each of m and n is a number of repeating unit of the respective oxyalkylene units; 1m10; and 1n60.

A modified PVA that enables formation of a film superior in cold water solubility, mechanical strength, and chemical resistance is provided. The modified PVA comprises a monomer unit represented by formula (I), and a structural unit represented by formula (II): ##STR00001##
wherein: a content of the monomer unit (I) is from 0.05 mol % to 10 mol %, and a content of the structural unit (II) is from 0.001 mol % to 0.5 mol % with respect to the total monomer units in the modified PVA; a viscosity average degree of polymerization is from 300 to 3,000; and a degree of saponification is from 82 mol % to 99.5 mol %. In the formula (I): R.sup.1 represents a hydrogen atom, or a methyl group; and R.sup.2 represents R.sup.3SO.sub.3.sup.X.sup.+, R.sup.3N.sup.+(R.sup.4).sub.3Cl.sup., or a hydrogen atom, R.sup.3 representing an alkanediyl group, X.sup.+ representing a hydrogen atom, a metal atom, or an ammonium group, and R.sup.4 representing an alkyl group.

A modified PVA that enables formation of a film superior in cold water solubility, mechanical strength, and chemical resistance is provided. The modified PVA comprises a monomer unit represented by formula (I), and a structural unit represented by formula (II): ##STR00001##
wherein: a content of the monomer unit (I) is from 0.05 mol % to 10 mol %, and a content of the structural unit (II) is from 0.001 mol % to 0.5 mol % with respect to the total monomer units in the modified PVA; a viscosity average degree of polymerization is from 300 to 3,000; and a degree of saponification is from 82 mol % to 99.5 mol %. In the formula (I): R.sup.1 represents a hydrogen atom, or a methyl group; and R.sup.2 represents R.sup.3SO.sub.3.sup.X.sup.+, R.sup.3N.sup.+(R.sup.4).sub.3Cl.sup., or a hydrogen atom, R.sup.3 representing an alkanediyl group, X.sup.+ representing a hydrogen atom, a metal atom, or an ammonium group, and R.sup.4 representing an alkyl group.

A dental cement hardened by a cement reaction involving the specific polymerizable polyacidic polymer and optionally additional crosslinkable groups, has reduced shrinkage and improved mechanical properties, in particular with regard to flexural strength and fracture toughness. Moreover, the specific polymerizable polyacidic polymer of the present invention contains a high number of acidic groups which is not reduced by the presence of polymerizable moieties, whereby water solubility of the uncured polymer is not impaired by the presence of the polymerizable moieties.

A dental cement hardened by a cement reaction involving the specific polymerizable polyacidic polymer and optionally additional crosslinkable groups, has reduced shrinkage and improved mechanical properties, in particular with regard to flexural strength and fracture toughness. Moreover, the specific polymerizable polyacidic polymer of the present invention contains a high number of acidic groups which is not reduced by the presence of polymerizable moieties, whereby water solubility of the uncured polymer is not impaired by the presence of the polymerizable moieties.

A modified PVA that enables formation of a film superior in cold water solubility, mechanical strength, and chemical resistance is provided. The modified PVA comprises a monomer unit represented by formula (I), and a structural unit represented by formula (II):

##STR00001##

wherein: a content of the monomer unit (I) is from 0.05 mol % to 10 mol %, and a content of the structural unit (II) is from 0.001 mol % to 0.5 mol % with respect to the total monomer units in the modified PVA; a viscosity average degree of polymerization is from 300 to 3,000; and a degree of saponification is from 82 mol % to 99.5 mol %. In the formula (I): R.sup.1 represents a hydrogen atom, or a methyl group; and R.sup.2 represents R.sup.3SO.sub.3.sup.X.sup.+, R.sup.3N.sup.+(R.sup.4).sub.3Cl.sup., or a hydrogen atom, R.sup.3 representing an alkanediyl group, X.sup.+ representing a hydrogen atom, a metal atom, or an ammonium group, and R.sup.4 representing an alkyl group.

A modified PVA that enables formation of a film superior in cold water solubility, mechanical strength, and chemical resistance is provided. The modified PVA comprises a monomer unit represented by formula (I), and a structural unit represented by formula (II):

##STR00001##

wherein: a content of the monomer unit (I) is from 0.05 mol % to 10 mol %, and a content of the structural unit (II) is from 0.001 mol % to 0.5 mol % with respect to the total monomer units in the modified PVA; a viscosity average degree of polymerization is from 300 to 3,000; and a degree of saponification is from 82 mol % to 99.5 mol %. In the formula (I): R.sup.1 represents a hydrogen atom, or a methyl group; and R.sup.2 represents R.sup.3SO.sub.3.sup.X.sup.+, R.sup.3N.sup.+(R.sup.4).sub.3Cl.sup., or a hydrogen atom, R.sup.3 representing an alkanediyl group, X.sup.+ representing a hydrogen atom, a metal atom, or an ammonium group, and R.sup.4 representing an alkyl group.

Disclosed pressure sensitive adhesive compositions, having enhanced heat resistance, obtained by the emulsion polymerization of (a) one or more acrylic acid ester or (meth)acrylate acid ester(s), (b) one or more hydroxyl functional (meth)acrylic monomer and (c) one or more ureido substituted (meth)acrylate monomers(s).