A crosslinking material, the crosslinking material comprising the reaction product of a reaction mixture comprising: (ii) ≥70% by weight of a cyclic unsaturated acid anhydride and/or diacid derivative thereof by total solid weight of the monomers from which the crosslinking material is formed; (ii) optionally, an ethylenically unsaturated monomer; and (iii) optionally, an alcohol, amine, thiol and/or water, wherein at least a portion of the cyclic unsaturated acid anhydride and/or diacid derivative thereof is reacted with the alcohol, amine, thiol and/or water, when present; and wherein the crosslinking material has an acid number of at least 100 mg KOH/g.

A crosslinking material, the crosslinking material comprising the reaction product of a reaction mixture comprising: (ii) ≥70% by weight of a cyclic unsaturated acid anhydride and/or diacid derivative thereof by total solid weight of the monomers from which the crosslinking material is formed; (ii) optionally, an ethylenically unsaturated monomer; and (iii) optionally, an alcohol, amine, thiol and/or water, wherein at least a portion of the cyclic unsaturated acid anhydride and/or diacid derivative thereof is reacted with the alcohol, amine, thiol and/or water, when present; and wherein the crosslinking material has an acid number of at least 100 mg KOH/g.

A water-soluble film includes a polyvinyl alcohol resin (A) as a main component, wherein the ratio (X.sub.TD/X.sub.MD) of a degree of elongation (X.sub.TD) in the transverse direction (TD) of the water-soluble film to a degree of elongation (X.sub.MD) in the machine direction (MD) thereof when the water-soluble film is floated on the surface of water at 20° C. for 60 seconds is from 1.05 to 1.5. The water-soluble film exhibits reduced curling, exhibits reduced positional shift, and shows satisfactory sealability while forming a package.

A water-soluble film includes a polyvinyl alcohol resin (A) as a main component, wherein the ratio (X.sub.TD/X.sub.MD) of a degree of elongation (X.sub.TD) in the transverse direction (TD) of the water-soluble film to a degree of elongation (X.sub.MD) in the machine direction (MD) thereof when the water-soluble film is floated on the surface of water at 20° C. for 60 seconds is from 1.05 to 1.5. The water-soluble film exhibits reduced curling, exhibits reduced positional shift, and shows satisfactory sealability while forming a package.

A nitrile group-containing copolymer rubber including 10 to 60 wt % of an α,β-ethylenically unsaturated nitrile monomer unit and 1 to 60 wt % of an α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit, and having an iodine value of 120 or less, wherein a processability index Ipro (Ipro=CC×SA) is 0.0030 or less, where the processability index Ipro is the product of the carboxyl group content CC, which is the number of moles of carboxyl groups per 100 g of nitrile group-containing copolymer rubber, and the absorbance area SA of a carboxylic anhydride group determined by infrared spectroscopy.

A nitrile group-containing copolymer rubber including 10 to 60 wt % of an α,β-ethylenically unsaturated nitrile monomer unit and 1 to 60 wt % of an α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit, and having an iodine value of 120 or less, wherein a processability index Ipro (Ipro=CC×SA) is 0.0030 or less, where the processability index Ipro is the product of the carboxyl group content CC, which is the number of moles of carboxyl groups per 100 g of nitrile group-containing copolymer rubber, and the absorbance area SA of a carboxylic anhydride group determined by infrared spectroscopy.

The present invention aims to provide an acrylic copolymer capable of maintaining excellent storage stability in the uncrosslinked state even after long-term exposure to high temperatures, and a crosslinked acrylic rubber product produced from the acrylic copolymer which maintains good normal-state properties and good water resistance. The present invention is based on the finding that an acrylic copolymer produced by polymerizing a liquid mixture of an alkoxyalkyl (meth)acrylate containing an alkoxyalkyl group and a crosslinkable monomer containing a carboxy group has excellent storage stability and that a crosslinked product produced from the acrylic copolymer has good normal-state properties and good water resistance.

The present invention aims to provide an acrylic copolymer capable of maintaining excellent storage stability in the uncrosslinked state even after long-term exposure to high temperatures, and a crosslinked acrylic rubber product produced from the acrylic copolymer which maintains good normal-state properties and good water resistance. The present invention is based on the finding that an acrylic copolymer produced by polymerizing a liquid mixture of an alkoxyalkyl (meth)acrylate containing an alkoxyalkyl group and a crosslinkable monomer containing a carboxy group has excellent storage stability and that a crosslinked product produced from the acrylic copolymer has good normal-state properties and good water resistance.

The present invention aims to provide an acrylic copolymer capable of maintaining excellent storage stability in the uncrosslinked state even after long-term exposure to high temperatures, and a crosslinked acrylic rubber product produced from the acrylic copolymer which maintains good normal-state properties and good water resistance. The present invention is based on the finding that an acrylic copolymer produced by polymerizing a liquid mixture of an alkoxyalkyl (meth)acrylate containing an alkoxyalkyl group and a crosslinkable monomer containing a carboxy group has excellent storage stability and that a crosslinked product produced from the acrylic copolymer has good normal-state properties and good water resistance.

The present invention relates to a vinyl chloride-based polymer containing an unsaturated fatty acid ester at a specific ratio, a method for preparing the same, a thermoplastic resin composition containing the same, and a thermoplastic resin molded article produced from the composition. The vinyl chloride-based polymer may have good processability, and thus, the thermoplastic resin molded article produced from the thermoplastic resin composition containing the vinyl chloride-based polymer may have high impact strength and improved appearance characteristics.