Stabilized polyethylene

Patent metadata

Field	Value
Publication number	US-9951212-B2
Application number	US-201615098601-A
Country	US
Kind code	B2
Filing date	Apr 14, 2016
Priority date	Apr 24, 2012
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

Polyethylene is often stabilized with the combination of a primary antioxidant (such as a hindered phenol, a hydroxylamine or a lactone) and a secondary antioxidant (such as a phosphonite, a monophosphite, or a diphosphite). The diphosphite additives are not completely compatible with “linear” polyethylene. This results in “blooming” of the diphosphite to the surface of the finished polyethylene part or polyethylene film. The use of a preblend of ethylene vinyl alcohol (EVOH) and diphosphite mitigates this problem.

First claim

The invention claimed is:

1. A stabilized polyethylene composition comprising:
A) a linear polyethylene copolymer that is characterized by having:
i. a melt index, I 2 , of from 0.1 to 20 grams per 10 minutes; and
ii. a density of from 0.890 to 0.955 g/cc; and

B) an EVOH/diphosphite preblend comprising:
a. from 30 to 90 weight % of a thermoplastic ethylene vinyl alcohol copolymer; and
b. from 10 to 70 weight % of a diphosphite antioxidant,
each based on the weight of said EVOH/Diphosphate preblend

wherein said EVOH/diphosphite preblend is:
1) dispersed within said polyethylene composition and
2) present in an amount that is sufficient to provide from 200 to 2,000 parts per million by weight of said diphosphite, based on the total weight of said polyethylene composition.

2. The composition of claim 1 where said linear polyethylene has a melt index, I 2 , of from 0.3 to 10 grams per 10 minutes.

3. The composition of claim 1 wherein said thermoplastic ethylene vinyl alcohol copolymer contains from 25 to 50 mole % ethylene.

4. The composition of claim 1 wherein said EVOH/diphosphite preblend comprises from 60 to 90 weight % of a thermoplastic ethylene vinyl alcohol copolymer, based on the weight of said EVOH/diphosphate preblend.

5. The composition of claim 1 wherein said diphosphite is selected from the group consisting of bis(2,4 di-tert-butylphenyl) pentaerythritol diphosphite; bis(2,6-di-tert-butyl-4-methylpenyl) pentaerythritol diphosphite; and bis(2,4-dicumylphenyl) pentaerythritol diphosphite.

Assignees

• Nova Chem Int Sa

Inventors

• Tikuisis Tony
• Ho Kam Wah
• Borse Nitin

Classifications

• C08J2429/04

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

• C08J2323/04

  Homopolymers or copolymers of ethene · CPC title

• C08L29/06

  Copolymers of allyl alcohol · CPC title

• C08L29/04

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

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title