Modified vinyl alcohol polymer powder having reduced methanol content and production method therefor, and water-soluble film and packaging material

Patent metadata

Field	Value
Publication number	US-10988606-B2
Application number	US-201716337224-A
Country	US
Kind code	B2
Filing date	Apr 13, 2017
Priority date	Sep 28, 2016
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

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.

First claim

The invention claimed is:

1. A modified vinyl alcohol polymer powder, comprising:
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,
wherein the modified vinyl alcohol polymer powder has a methanol content of 0.01 weight % or more and less than 3.0 weight % as measured by headspace gas chromatography of 500 mg of the polymer powder,
the modified vinyl alcohol polymer powder comprises 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, and
at least 95 weight % of all particles of the modified vinyl alcohol polymer powder pass through a sieve with 1.00 mm openings.

2. The modified vinyl alcohol polymer powder according to claim 1 , wherein the derivative (A) of an ethylenically unsaturated dicarboxylic acid is a monoester, a diester, or an anhydride of an ethylenically unsaturated dicarboxylic acid.

3. The modified vinyl alcohol polymer powder according to claim 1 , wherein the derivative (A) of an ethylenically unsaturated dicarboxylic acid comprises a maleic acid monoalkyl ester, a maleic acid dialkyl ester, maleic anhydride, a fumaric acid monoalkyl ester, or a fumaric acid dialkyl ester.

4. The modified vinyl alcohol polymer powder according to claim 1 , wherein at least a part of the structural unit derived from the derivative (A) of an ethylenically unsaturated dicarboxylic acid is a structural unit represented by formula (I):

wherein R 1 is a hydrogen atom, or a linear or branched alkyl group of 1 to 8 carbon atoms, and
R 2 is a metal atom, a hydrogen atom, or a linear or branched alkyl group of 1 to 8 carbon atoms, and
the modified vinyl alcohol polymer powder satisfies formula (Q):
0.05≤ Y/X< 0.98  (Q),

wherein X is the content of the structural unit derived from the derivative (A) of an ethylenically unsaturated dicarboxylic acid, and
Y is the content of the structural unit represented by formula (I).

5. The modified vinyl alcohol polymer powder according to claim 1 , wherein at least 30 weight % of all particles of the modified vinyl alcohol polymer powder pass through a sieve with 500 μm-openings.

6. A method for producing the modified vinyl alcohol polymer powder of claim 1 , the method comprising:
obtaining a vinyl ester copolymer (C) through copolymerization of the derivative (A) of an ethylenically unsaturated dicarboxylic acid with a vinyl ester monomer (B);
saponifying the vinyl ester copolymer (C) with an alkali catalyst in a methanol solvent; and
impregnating the saponified polymer with a washing solution comprising 45 volume % or more of methyl acetate.

7. The method according to claim 6 , wherein a solution prepared to comprise more than 20 weight % of the vinyl ester copolymer (C) is mixed with the alkali catalyst in the saponifying, and a resulting semi-solid or solid product is pulverized with a pulverizer.

8. The method according to claim 6 , wherein the saponifying does not involve neutralization with an acid.

9. A method for producing the modified vinyl alcohol polymer powder of claim 1 , the method comprising:
obtaining a vinyl ester copolymer (C) through copolymerization of the derivative (A) of an ethylenically unsaturated dicarboxylic acid with a vinyl ester monomer (B); and
saponifying the vinyl ester copolymer (C) with an alkali catalyst in a methanol solvent,
the vinyl ester copolymer (C) having a concentration of less than 10 weight % in the methanol solvent in the saponifying.

10. A water-soluble film, comprising the modified vinyl alcohol polymer powder of claim 1 .

11. The water-soluble film of claim 10 , wherein the water-soluble film further comprises a plasticizer.

12. The water-soluble film of claim 10 , wherein the water-soluble film further comprises a surfactant.

13. A packaging material, comprising a chemical packed in the water-soluble film of claim 10 .

14. The packaging material of claim 13 , wherein the chemical is an agrichemical or a detergent.

Assignees

• Kuraray Co

Inventors

• Nii Shinsuke
• Kumaki Yosuke
• Horiguchi Junpei
• Fukuhara Tadahito
• Tanida Tatsuya

Classifications

• C08F8/12 Primary

  Hydrolysis · CPC title

• C08F222/00

  Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof · CPC title

• C08F218/08

  Vinyl acetate · CPC title

• C08F222/10

  Esters · CPC title

• C08J5/18

  Manufacture of films or sheets · CPC title