Ethylene-vinyl alcohol copolymer particles, method for producing same and use of same

Patent metadata

Field	Value
Publication number	US-11518902-B2
Application number	US-201816756243-A
Country	US
Kind code	B2
Filing date	Oct 16, 2018
Priority date	Oct 17, 2017
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

The present invention relates to ethylene-vinyl alcohol copolymer particles, comprising an ethylene-vinyl alcohol copolymer having an ethylene unit content of 1 mol % or more and less than 20 mol %, a viscosity-average polymerization degree of 200 to 5000, and a saponification degree of 80 to 99.99 mol %, wherein a crystallinity in water Cw (30° C.) at 30° C. and a crystallinity in water Cw (70° C.) at 70° C. as determined by pulse NMR satisfy formula (I). There is thus provided ethylene-vinyl alcohol copolymer particles having excellent solubility in water and excellent gas barrier performance.

First claim

The invention claimed is:

1. Ethylene-vinyl alcohol copolymer particles, comprising:
an ethylene-vinyl alcohol copolymer having an ethylene unit content of 1 mol % or more and less than 20 mol %, a viscosity-average polymerization degree of 200 to 5000, and a saponification degree of 80 to 99.99 mol %,
wherein a crystallinity in water Cw (30° C.) at 30° C. and a crystallinity in water Cw (70° C.) at 70° C. as determined by pulse NMR satisfy formula (I):

2. The ethylene-vinyl alcohol copolymer particles according to claim 1 , wherein the saponification degree is 85 mol % or more.

3. The ethylene-vinyl alcohol copolymer particles according to claim 1 , wherein a content of particles passing through a sieve with a mesh size of 2.5 mm is 80% by mass or more, and
a content of particles passing through a sieve with a mesh size of 0.15 mm is 20% by mass or less.

4. A method for producing the ethylene-vinyl alcohol copolymer particles according to claim 1 , the method comprising:
copolymerizing ethylene and a vinyl ester to give an ethylene-vinyl ester copolymer;
saponifying the ethylene-vinyl ester copolymer to give a solid block comprising an ethylene-vinyl alcohol copolymer and a solvent;
pulverizing the solid block to give wet particles;
deliquoring the wet particles by mechanically removing some of the solvent from the wet particles to give deliquored particles; and
drying the deliquored particles to remove remaining solvent from the deliquored particles by heating to give dry particles,
wherein
the deliquored particles contain from 40 to 65% by mass of the solvent; and
in the deliquored particles, a content of particles passing through a sieve with a mesh size of 5.6 mm is 80% by mass or more, and a content of particles passing through a sieve with a mesh size of 1.0 mm is less than 2% by mass.

5. The production method according to claim 4 , wherein the pulverizing comprises pulverizing the solid block with the pulverizer,
a Rockwell hardness of a cutting blade of the pulverizer is 40 to 70, and
a rotation speed of the cutting blade is 200 to 550 rpm.

6. The production method according to claim 4 , wherein the deliquoring comprising deliquoring the wet particles with a centrifugal deliquoring machine.

7. The production method according to claim 4 , further comprising an additional pulverizing step after the drying.

8. A method for preparing an aqueous solution, comprising:
dissolving the ethylene-vinyl alcohol copolymer particles according to claim 1 in water.

9. A coating method, comprising:
applying an aqueous solution prepared by the method according to claim 8 to a substrate, to form a coating film.

10. The coating method according to claim 9 , wherein the coating film is a gas barrier coating film.

11. A coating agent comprising the ethylene-vinyl alcohol copolymer particles according to claim 1 .

12. The coating agent according to claim 11 , further comprising at least one selected from the group consisting of an inorganic lamellar compound, a crosslinking agent, a surfactant, a leveling agent, an antifungal agent, and a preservative.

13. A film made of the coating agent according to claim 11 .

14. A laminate wherein the coating agent according to claim 11 is applied to a substrate.

15. The laminate according to claim 14 , wherein the substrate is a paper.

16. The laminate according to claim 14 , wherein an adhesive component layer is inserted between a coating layer made of the coating agent and the substrate.

Assignees

• Kuraray Co

Inventors

• Tanida Tatsuya
• Morikawa Keisuke
• Nakamae Masato
• Inada Seisuke

Classifications

• C08F8/12

  Hydrolysis · CPC title

• C08F216/06 Primary

  Polyvinyl alcohol {; Vinyl alcohol} · CPC title

• C08F2800/10

  as molar percentages · CPC title

• C08F218/08

  Vinyl acetate · CPC title

• C08J7/043

  Improving the adhesiveness of the coatings per se, e.g. forming primers (adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50) · CPC title