A modified vinyl alcohol polymer powder having a structural unit derived from a derivative of an ethylenically unsaturated dicarboxylic acid, and containing a reduced amount of methanol, and a trace amount of a component that does not dissolve in water. The present invention relates to a modified vinyl alcohol polymer powder containing a structural unit derived from a derivative (A) of an ethylenically unsaturated dicarboxylic acid in a content (X) of 0.05 mol % or more and 10 mol % or less, and having a degree of saponification of 80.0 mol % or more and 99.9 mol % or less, the modified vinyl alcohol polymer powder has a methanol content of 0.01 weight % or more and less than 3.0 weight %, the modified vinyl alcohol polymer powder contains 0.1 ppm or more and less than 2,000 ppm of a component that is insoluble in a 90 C., 5 weight % aqueous solution.

Ethylene-vinyl alcohol copolymer pellets comprise an ethylene-vinyl alcohol copolymer and water, and have a water content of not higher than 0.5 wt. %, wherein the ratio (Y/Z) of a lactone ring content (Y) to the sum (Z) of a carboxylic acid content (X) and the lactone ring content (Y) in terminal structures of the ethylene-vinyl alcohol copolymer is not less than 60 mol %. The pellets are excellent in high-temperature thermal decomposition-suppressing effect and thermal stability, and are free from odor emanation and coloration even if being processed at a higher temperature.

Ethylene-vinyl alcohol copolymer pellets comprise an ethylene-vinyl alcohol copolymer and water, and have a water content of not higher than 0.5 wt. %, wherein the ratio (Y/Z) of a lactone ring content (Y) to the sum (Z) of a carboxylic acid content (X) and the lactone ring content (Y) in terminal structures of the ethylene-vinyl alcohol copolymer is not less than 60 mol %. The pellets are excellent in high-temperature thermal decomposition-suppressing effect and thermal stability, and are free from odor emanation and coloration even if being processed at a higher temperature.

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 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 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.

Copolymers of a polyvinyl butyral backbone with polylactic acid grafts and their compounds are disclosed, which can be used to produce clear, flexible and ductile bio-based films. The copolymers are amorphous and have been shown to maintain clarity, flexibility, and ductility after continuous exposure to thermal aging at 80 C. for one week.