Polyvinyl alcohol-based crosslinked copolymer

Patent metadata

Field	Value
Publication number	US-12240928-B2
Application number	US-201917418132-A
Country	US
Kind code	B2
Filing date	Dec 26, 2019
Priority date	Dec 28, 2018
Publication date	Mar 4, 2025
Grant date	Mar 4, 2025

Abstract

A polyvinyl alcohol-based crosslinked copolymer may include an unsaturated monocarboxylic acid-based structural unit, wherein an amount of carboxylate-forming structural units in the crosslinked copolymer is 1% by mole or more and 35% by mole or less with respect to all structural units constituting the crosslinked copolymer, and a solubility of the crosslinked copolymer in water is 90% or less.

First claim

The invention claimed is:

1. A polyvinyl alcohol-based crosslinked copolymer, comprising:
an unsaturated monocarboxylic acid-based structural unit,
vinyl alcohol units, and
acetal crosslinking structures formed with a polyfunctional aldehyde having 2-20 carbon atoms,
wherein
an amount of carboxylate-forming structural units in the crosslinked copolymer is in a range of from 1.5 to 15 mol. %, based on total structural units in the crosslinked copolymer,
an amount of vinyl alcohol units in the polyvinyl alcohol-based crosslinked copolymer is in a range of from 20 to 98.5 mol. %, based on the total structural units in the crosslinked copolymer,
an amount of acetalized vinyl alcohol units of the crosslinked copolymer is from 0.01% to 50% by mole of the total of vinyl alcohol units,
and
a solubility of the crosslinked copolymer in water is 5% or more and 90% or less.

2. The copolymer of claim 1 , comprising a potassium ion as a counter cation of the carboxylate.

3. The copolymer of claim 1 , wherein an amount of water that can be absorbed by a plant per 1 g of the polyvinyl alcohol-based crosslinked copolymer is in a range of from 10 to 100 g.

4. The copolymer of claim 1 , wherein the polyfunctional aldehyde is at least one selected from the group consisting of glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, adipaldehyde, malealdehyde, fumaraldehyde, tartaraldehyde, citraldehyde, terephthalaldehyde, isophthalaldehyde, phthalaldehyde, 1,9-nonanedial, and ethylenediamine tetraacetaldehyde.

5. The copolymer of claim 1 , wherein the unsaturated monocarboxylic acid-based structural unit is derived from acrylic acid or a derivative thereof, or methacrylic acid or a derivative thereof.

6. A method of producing a polyvinyl alcohol-based crosslinked copolymer, the method comprising:
reacting a polyvinyl alcohol-based copolymer containing an unsaturated monocarboxylic acid-based structural unit with a polyfunctional aldehyde having 2-20 carbon atoms,
wherein an amount of carboxylate-forming structural units in the crosslinked copolymer is in a range of from 1.5 to 15 mol. %, based on total structural units in the crosslinked copolymer,
an amount of vinyl alcohol units in the polyvinyl alcohol-based crosslinked copolymer is in a range of from 20 to 98.5 mol. %, based on the total structural units in the crosslinked copolymer,
an amount of acetalized vinyl alcohol units of the crosslinked copolymer is from 0.01% to 50% by mole of the total of vinyl alcohol units,
and a solubility of the crosslinked copolymer in water is 5% or more and 90% or less.

7. The method of claim 6 , further comprising, in the presence of a solvent capable of swelling the polyvinyl alcohol-based copolymer:
reacting particles of the polyvinyl alcohol-based copolymer swollen with the solvent with the crosslinking agent.

8. A water-retaining material, comprising:
the copolymer of claim 1 .

9. An agricultural water retaining material, comprising the water-retaining material of claim 8 .

Assignees

• Kuraray Co

Inventors

• Saegusa Yusuke
• Baba Masahiro
• Kato Toshinori

Classifications

• C08F220/14

  Methyl esters {, e.g. methyl (meth)acrylate} · CPC title

• C08K5/07

  Aldehydes; Ketones · CPC title

• C08F220/06

  Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof · CPC title

• A01G24/35 Primary

  containing water-absorbing polymers · CPC title

• C08L29/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title