Barrier film composition

Patent metadata

Field	Value
Publication number	US-11401392-B2
Application number	US-201916682015-A
Country	US
Kind code	B2
Filing date	Nov 13, 2019
Priority date	Nov 16, 2018
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

Barrier films are prepared from a composition comprising 1) a blend of two high density polyethylene HDPE blend components, 2) zinc glycerolate and 3) a dispersion aid/synergist. The two high density polyethylene blend components have substantially different melt indices. It is difficult to properly mix the zinc glycerolate into this HDPE blend. The use of the dispersion aid/synergist improves the water vapor transmission rate (WVTR) of polyethylene film (in comparison to barrier films made with zinc glycerolate, in the absence of the dispersion aid/synergist). The resulting barrier films are suitable for the preparation of packaging for dry foods such as crackers and breakfast cereals.

First claim

We claim:

1. A barrier film comprising at least one extruded polyethylene layer, wherein said at least one extruded polyethylene layer comprises:
I) zinc glycerolate;
II) a high density polyethylene blend composition comprising:
II-i) from 5 to 60 weight % of at least one high density polyethylene blend component a) having a high melt index, I 2 ; and
II-ii) from 95 to 40 weight % of at least one high density polyethylene blend component b) having a low melt index, I 2 ′, wherein I 2 ′ is less than I 2 , wherein:
a) said zinc glycerolate is present at about 200 to 2000 parts per million based on the weight of said high density polyethylene blend composition;
b) each of said blend component a) and blend component b) has a density of from 0.950 to 0.975 g/cc;
c) the melt index, I 2 , of said high density polyethylene blend composition is from 0.5 to 10 grams/10 minutes; and
d) the I 2 ratio, obtained by dividing the I 2 value of said blend component a) by the I 2 ′ value of said blend component b), is greater than 10/1; and

III) a synergist, wherein said synergist comprises zinc stearate, calcium stearate, or a mixture of zinc stearate and calcium stearate; and wherein said synergist is present at about 30 to about 55 weight % of the weight of said zinc glycerolate.

2. The barrier film of claim 1 wherein said high density polyethylene blend composition comprises from 10 to 40 weight % of said component a) and from 90 to 60 weight % of said component b).

3. The barrier film of claim 1 wherein said high density polyethylene blend composition comprises from 20 to 40 weight % of said component a) and from 80 to 60 weight % of said component b).

4. The barrier film of claim 1 wherein said blend component a) is further characterized by having a molecular weight distribution, Mw/Mn, of from 2 to 4.

5. The barrier film of claim 1 wherein said high density polyethylene blend composition has a density from 0.955 to 0.965 g/cc.

6. The barrier film of claim 1 wherein said high density polyethylene blend composition has a melt index, I 2 , of from 0.8 to 8 grams/10 minutes.

7. The barrier film of claim 1 wherein said high density blend composition has a molecular weight distribution, Mw/Mn, of from 6 to 12.

8. A process to prepare a barrier film for food packaging, said process comprising the film extrusion of a composition comprising:
I) zinc glycerolate;
II) a high density polyethylene blend composition comprising:
II-i) from 5 to 60 weight % of at least one high density polyethylene blend component a) having a high melt index, I 2 ; and
II-ii) from 95 to 40 weight % of at least one high density polyethylene blend component b) having a low melt index, I 2 ′, wherein I 2 ′ is less than I 2 , wherein:
a) said zinc glycerolate is added at about 200 to 2000 parts per million based on the weight of said high density polyethylene blend composition;
b) each of said blend component a) and blend component b) has a density of from 0.950 to 0.975 g/cc;
c) the melt index, I 2 , of said high density polyethylene blend composition is from 0.5 to 10 grams/10 minutes; and
d) the I 2 ratio, obtained by dividing the I 2 value of said blend component a) by the I 2 ′ value of said blend component b), is greater than 10/1; and

III) a synergist, wherein said synergist comprises zinc stearate, calcium stearate, or a mixture of zinc stearate and calcium stearate; and wherein said synergist is present at about 30 to about 55 weight % of the weight of said zinc glycerolate.

9. The process of claim 8 wherein said high density polyethylene blend composition comprises from 10 to 40 weight % of said component a) and from 90 to 60 weight % of said component b).

10. The process of claim 8 wherein said blend component a) is further characterized by having a molecular weight distribution, Mw/Mn, of from 2 to 4.

11. The process of claim 8 wherein conducted at a blow up ratio of from 1.5/1 to 4/1.

12. The process of claim 8 wherein said barrier film has a water vapor transmission rate that is from 15 to 40% lower than the water vapor transmission rate of a control film that is prepared in the absence of said synergist.

Assignees

• Nova Chem Int Sa

Inventors

• Wasylenko Derek
• Lightbody Owen
• Tikuisis Tony
• Chisholm P Scott

Classifications

• C08L23/04 Primary

  Homopolymers or copolymers of ethene · CPC title

• B65D81/24

  Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants (with thermal insulation B65D81/38) · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• C08L2203/16

  used for films · CPC title