Ethylene-vinyl alcohol copolymer composition pellets, and production method for ethylene-vinyl alcohol copolymer composition pellets

Patent metadata

Field	Value
Publication number	US-11015029-B2
Application number	US-201916451581-A
Country	US
Kind code	B2
Filing date	Jun 25, 2019
Priority date	Dec 28, 2016
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

Ethylene-vinyl alcohol copolymer composition pellets comprise: an ethylene-vinyl alcohol copolymer, a conjugated polyene, and a predetermined amount of at least one fisheye-suppressing component; wherein pellet surface portions of the ethylene-vinyl alcohol copolymer composition pellets have a conjugated polyene content of not lower than 30 ppb based on the weight of the pellets. Such ethylene-vinyl alcohol copolymer composition pellets are capable of reliably suppressing occurrence of minute fisheyes having a diameter of 200 μm or smaller.

First claim

The invention claimed is:

1. Ethylene-vinyl alcohol copolymer composition pellets comprising:
an ethylene-vinyl alcohol copolymer;
a conjugated polyene; and
at least one component selected from the group consisting of:
(A) 10 to 400 ppm of a lubricant based on a weight of the ethylene-vinyl alcohol copolymer composition pellets;
(B) 10 to 250 ppm of a boron compound based on the weight of the ethylene-vinyl alcohol copolymer composition pellets; and
(C) 1 to 500 ppm of an alkali metal based on the weight of the ethylene-vinyl alcohol copolymer composition pellets;
wherein pellet surface portions of the ethylene-vinyl alcohol copolymer composition pellets have a conjugated polyene content of not lower than 30 ppb based on the weight of the ethylene-vinyl alcohol copolymer composition pellets; and
wherein a weight-based content ratio (surface conjugated polyene content/overall conjugated polyene content) between the conjugated polyene content of the pellet surface portions of the ethylene-vinyl alcohol copolymer composition pellets and the overall conjugated polyene content of the ethylene-vinyl alcohol copolymer composition pellets is not lower than 1.5×10 −4 .

2. The ethylene-vinyl alcohol copolymer composition pellets according to claim 1 , wherein the conjugated polyene content of the pellet surface portions is determined by dissolving 20 g of the ethylene-vinyl alcohol copolymer composition pellets in 30 mL of a mixed solvent having a water/methanol volume ratio of 1/1 with stirring for 10 minutes, and dividing the conjugated polyene amount contained in a resulting solution by the weight of the ethylene-vinyl alcohol copolymer composition pellets.

3. The ethylene-vinyl alcohol copolymer composition pellets according to claim 1 , which have an overall conjugated polyene content of 0.1 to 10,000 ppm based on the weight of the pellets.

4. The ethylene-vinyl alcohol copolymer composition pellets according to claim 1 ,
wherein the conjugated polyene is at least one selected from the group consisting of sorbic acid, a sorbic acid ester, and a sorbic acid salt.

5. A method for producing the ethylene-vinyl alcohol copolymer composition pellets according to claim 1 , comprising:
bringing pellets of an ethylene-vinyl alcohol copolymer into contact with a treatment liquid containing a conjugated polyene; and
bringing the ethylene-vinyl alcohol copolymer pellets into contact with at least one component selected from the group consisting of a lubricant, a boron compound, and an alkali metal.

6. The ethylene-vinyl alcohol copolymer composition pellet production method according to claim 5 , wherein the ethylene-vinyl alcohol copolymer pellets are prepared by solidifying and pelletizing an alcohol solution or a water/alcohol mixed solution of the ethylene-vinyl alcohol copolymer.

7. The ethylene-vinyl alcohol copolymer composition pellet production method according to claim 5 , wherein the ethylene-vinyl alcohol copolymer pellets are porous ethylene-vinyl alcohol copolymer pellets.

8. The ethylene-vinyl alcohol copolymer composition pellet production method according to claim 5 ,
further comprising adding the conjugated polyene as a polymerization inhibitor to an ethylene-vinyl ester copolymer and then saponifying the ethylene-vinyl ester copolymer to prepare the ethylene-vinyl alcohol copolymer.

Assignees

• Mitsubishi Chem Corp

Inventors

• SENO Ryuta
• Hatanaka Makoto

Classifications

• B29B2009/163

  Coating, i.e. applying a layer of liquid or solid material on the granule · CPC title

• B29B2009/161

  Absorbing, i.e. introducing a gas, a liquid or a solid material into the granules · CPC title

• B29B9/16

  Auxiliary treatment of granules · CPC title

• C08K3/38

  Boron-containing compounds · CPC title

• C08K13/02

  Organic and inorganic ingredients · CPC title