Ethylene-vinyl alcohol copolymer, method of producing ethylene-vinyl alcohol copolymer, resin composition, and multilayer structure

Patent metadata

Field	Value
Publication number	US-11401355-B2
Application number	US-201815913069-A
Country	US
Kind code	B2
Filing date	Mar 6, 2018
Priority date	Sep 15, 2015
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

An ethylene-vinyl alcohol copolymer has an ethylene content of 20 to 60 mol % and includes a carboxylic acid group and a lactone ring group present at terminals thereof, wherein the molar concentration (Y/Z) of a lactone ring molar content (Y) to a sum (Z) of a carboxylic acid molar content (X) and the lactone ring molar content (Y) is not less than 58 mol %. The ethylene-vinyl alcohol copolymer is excellent in high-temperature thermal stability substantially without thermal decomposition, and is free from odor emanation and coloration even if being processed at a higher temperature.

First claim

The invention claimed is:

1. A method of producing an ethylene-vinyl alcohol copolymer comprising
an ethylene unit and a vinyl alcohol unit as monomer units, and
a carboxylic acid group and a lactone ring group present at terminals thereof,
wherein a molar concentration (Y/Z) of a lactone ring molar content (Y) to a sum (Z) of a carboxylic acid molar content (X) and the lactone ring molar content (Y) is not less than 63 mol %,
the method comprising:
[I] saponifying an ethylene-vinyl ester copolymer to provide an ethylene-vinyl alcohol copolymer intermediate product;
[II] chemically treating the ethylene-vinyl alcohol copolymer intermediate product with a chemical treatment liquid; and
[III] drying the chemically treated ethylene-vinyl alcohol copolymer intermediate product;
wherein a monovalent carboxylic acid concentration of the chemical treatment liquid is 1 to 50000 ppm in the chemical treatment [II];
wherein a weight-based ratio of the monovalent carboxylic acid concentration to a metal ion concentration (monovalent carboxylic acid concentration/metal ion concentration) is 13 to 100 in the chemical treatment liquid in the chemical treatment [II]; and
wherein the metal ion in the chemical treatment liquid is a metal ion of carboxylic acid metal salt.

2. The ethylene-vinyl alcohol copolymer production method according to claim 1 , wherein the chemical treatment [II] of chemically treating the ethylene-vinyl alcohol copolymer intermediate product with the chemical treatment liquid includes preparing a plurality of chemical treatment liquids having different carboxylic acid concentrations, and chemically treating the ethylene-vinyl alcohol copolymer intermediate product with the respective chemical treatment liquids on multiple stages, wherein the weight-based ratio of the monovalent carboxylic acid concentration to the metal ion concentration (monovalent carboxylic acid concentration/metal ion concentration) is 13 to 100 in a chemical treatment liquid having the highest monovalent carboxylic acid concentration among the plurality of chemical treatment liquids.

3. The ethylene-vinyl alcohol copolymer production method according to claim 1 , wherein the drying [III] is performed at a drying temperature of 80° C. to 150° C.

4. An ethylene-vinyl alcohol copolymer comprising
an ethylene unit and a vinyl alcohol unit as monomer units, and
a carboxylic acid group and a lactone ring group present at terminals thereof,
wherein a molar concentration (Y/Z) of a lactone ring molar content (Y) to a sum (Z) of a carboxylic acid molar content (X) and the lactone ring molar content (Y) is not less than 63 mol %, and
wherein the ethylene-vinyl alcohol copolymer does not comprise a 1,2-diol structure at a side chain thereof.

5. The ethylene-vinyl alcohol copolymer production method according to claim 1 , wherein the ethylene-vinyl alcohol copolymer does not comprise a 1,2-diol structure at a side chain thereof.

6. The ethylene-vinyl alcohol copolymer according to claim 4 , wherein the sum (Z) of the carboxylic acid molar content (X) and the lactone ring molar content (Y) is 0.01 to 0.3 mol % based on a total amount of the monomer units of the ethylene-vinyl alcohol copolymer.

7. The ethylene-vinyl alcohol copolymer according to claim 4 , wherein the lactone ring molar content (Y) is 0.01 to 0.3 mol % based on a total amount of the monomer units of the ethylene-vinyl alcohol copolymer.

8. The ethylene-vinyl alcohol copolymer according to claim 4 , wherein the carboxylic acid molar content (X) is 0.01 to 0.3 mol % based on a total amount of the monomer units of the ethylene-vinyl alcohol copolymer.

9. A resin composition comprising the ethylene-vinyl alcohol copolymer according to claim 4 .

10. A multilayer structure comprising at least one layer comprising the ethylene-vinyl alcohol copolymer according to claim 4 .

11. A multilayer structure comprising at least one layer comprising the resin composition according to claim 9 .

Assignees

• Nippon Synthetic Chem Ind Co Ltd
• Mitsubishi Chem Corp

Inventors

• Yoshida Tomonori
• Sato Nobuaki
• Taniguchi Masahiko

Classifications

• B32B2250/24

  All layers being polymeric · CPC title

• B32B2307/7242

  Non-permeable · CPC title

• C08F8/16 Primary

  Lactonisation · CPC title

• C08F2810/40

  taking place solely at one end or both ends of the polymer backbone, i.e. not in the side or lateral chains · CPC title

• B32B2250/03

  3 layers · CPC title