Biaxially-oriented polyethylene multilayer film with a matte surface

Patent metadata

Field	Value
Publication number	US-11376830-B2
Application number	US-201917252955-A
Country	US
Kind code	B2
Filing date	May 17, 2019
Priority date	Jun 29, 2018
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

A biaxially-oriented polyethylene (BOPE) multilayer film comprises a skin layer with a matte surface and a core, the skin layer with a matte surface comprising, in weight percent (wt %) based upon the weight of the skin layer: (1) from 20 to 80 wt % of an ethylene-based polymer, and (2) from 80 to 20 wt % of a propylene-based polymer; each of the ethylene-based polymer and the propylene-based polymer having a storage modulus, with a difference between the storage modulus of the ethylene-based polymer and the propylene-based polymer of greater than 40 megaPascals (MPa) at 110° C., and greater than 18 MPa at 120° C.

First claim

What is claimed is:

1. A biaxially-oriented polyethylene (BOPE) multilayer film comprising a skin layer with a matte surface and a core, the core comprising one or more layers, the film characterized by the following:
(A) the skin layer with a matte surface comprising, in weight percent (wt %) based upon the weight of the skin layer:
(1) from 20 to 80 wt % of an ethylene-based polymer, the ethylene-based polymer in the skin layer is an ethylene/C 4 -C 8 α-olefin copolymer with a density from 0.910 g/cc to 0.930 g/cc, and
(2) from 80 to 20 wt % of a propylene-based polymer;
each of the ethylene-based polymer and the propylene-based polymer having a storage modulus, with a difference between the storage modulus of the ethylene-based polymer and the propylene-based polymer of greater than 40 MPa at 110° C., and greater than 18 MPa at 120° C.;

(B) the matte surface of the skin layer has a gloss of less than 50% as measured by ASTM D2457 at an angle of 45°;
(C) the core comprising at least 50 wt % of an ethylene-based polymer based on the weight of all of the core layers;
(D) the film having a thickness, and the core comprising at least 50% of the film thickness; and
(E) the film is oriented in the machine direction at a draw ratio from 2:1 to 6:1, and in the cross direction from 2:1 to 11:1.

2. The BOPE multilayer film of claim 1 in which the difference between the storage modulus of the ethylene-based polymer and the propylene-based polymer is greater than 50 MPa at 110° C., and greater than 50 MPa at 120° C.

3. The BOPE multilayer film of claim 1 in which the ethylene-based polymer of the skin layer with a matte surface is a linear low density polyethylene (LLDPE).

4. The BOPE multilayer film of claim 1 in which the propylene-based polymer of the skin layer with a matte surface is one or more of a propylene random copolymer and a propylene-ethylene-butene terpolymer.

5. The BOPE multilayer film of claim 1 comprising two skin layers, one of which has a matte surface with a gloss of less than 50%, and the other of which has a gloss of 50% or greater.

6. The BOPE multilayer film of claim 1 in which the matte surface of the skin layer has a haze of greater than 50% as measured by ASTM D1003.

7. The BOPE multilayer film of claim 1 wherein the core comprises a plurality of layers comprising more than one core layer.

8. The BOPE multilayer film of claim 1 wherein the core comprises at least 3 layers comprising at least 3 core layers.

9. The BOPE multilayer film of claim 1 wherein the skin layer with a matte surface directly contacts the core; and
the core comprises from 50 wt % to 100 wt % of the ethylene-based polymer, based on the weight of all of the core layers.

10. The BOPE multilayer film of claim 1 wherein the skin layer with a matte surface comprises
an ethylene/C 4 -C 8 α-olefin copolymer;
a propylene/ethylene copolymer, having a difference in storage modulus from 100 MPa to 130 MPa at 110° C., and from 70 MPa to 80 MPa at 120° C.; and
the matte surface of the skin layer has (i) a gloss from 3% to 15% and (ii) a haze from 70% to 90%.

11. The BOPE multilayer film of claim 1 wherein the skin layer with a matte surface comprises
an ethylene/C 4 -C 8 α-olefin copolymer;
a propylene/ethylene/butene terpolymer, having a difference in storage modulus from greater than 40 MPa to 50 MPa, and from greater than 18 MPa to 20 MPa at 120° C.; and
the matte surface of the skin layer has (i) a gloss from 15% to 19% and (ii) a haze from greater than 50% to 55%.

12. The BOPE multilayer film of claim 1 comprising at least two core layers, each core layer composed of the same ethylene-based polymer.

13. The BOPE multilayer film of claim 12 wherein the ethylene-based polymer in the skin layer with a matte surface and the ethylene-based polymer in each core layer is the same ethylene-based polymer.

14. A package comprising the BOPE multilayer film of claim 1 .

15. The BOPE multilayer film of claim 1 wherein the skin layer is composed of a single ethylene-based polymer and a single propylene-based polymer.

16. The BOPE multilayer film of claim 7 wherein the ethylene-based polymer in each core layer is an ethylene/C 4 -C 8 α-olefin copolymer with a density from 0.910 g/cc to 0.930 g/cc.

17. The BOPE multilayer film of claim 16 wherein each layer of the core is composed of a single ethylene-based polymer.

18. The BOPE multilayer film of claim 17 wherein (A) the skin layer consists of
(i) from 20 wt % to 80 wt % of a single ethylene-based polymer,
(ii) from 80 wt % to 20 wt % of a single propylene-based polymer, and
(iii) optional additives.

Assignees

• Dow Global Technologies Llc

Inventors

• Wang Gang
• Yun Xiaobing
• Pan Jianping
• Xu Jingyi

Classifications

• B32B2307/406

  Bright, glossy, shiny surface · CPC title

• B32B2439/70

  Food packaging · CPC title

• B32B2307/408

  Matt, dull surface · CPC title

• B32B2250/03

  3 layers · CPC title

• B32B27/08

  of synthetic resin · CPC title