Films

Patent metadata

Field	Value
Publication number	US-10328678-B2
Application number	US-201415037470-A
Country	US
Kind code	B2
Filing date	Nov 19, 2014
Priority date	Nov 21, 2013
Publication date	Jun 25, 2019
Grant date	Jun 25, 2019

Abstract

A multilayer machine direction oriented film comprising at least an (A) layer and (B) layer, at least one of said (A) layer or (B) layer comprising at least 50 wt % of a multimodal linear low density polyethylene (LLDPE) having a density of 905 to 940 kg/m 3 and an MFR 2 of 0.01 to 20 g/10 min and comprising a lower molecular weight (LMW) component and a higher molecular weight (HMW) component; wherein said LMW component is an ethylene homopolymer and said HMW component is an ethylene polymer of ethylene with at least two C4-12 alpha olefins; wherein said film is a stretched film which is uniaxially oriented in the machine direction (MD) in a draw ratio of at least 1:3 and has a film thickness of at least 40 microns (after stretching) and wherein said film does not comprise a layer in which more than 50 wt % of said layer comprises a polymer component having a melting point (Tm) of 100° C. or less.

First claim

The invention claimed is:

1. A multilayer machine direction oriented film comprising at least an (A) layer and (B) layer,
wherein layer (A) layer comprises at least 50 wt % of a multimodal linear low density polyethylene (LLDPE) having a density of 905 to 935 kg/m 3 and an MFR 2 of 0.01 to 20 g/10 min which comprises a lower molecular weight (LMW) component and a higher molecular weight (HMW) component;
wherein said LMW component is an ethylene homopolymer and said HMW component is an ethylene polymer of ethylene with at least two C4-12 alpha olefins;
wherein layer (B) comprises (i) at least 50 wt % of a multimodal LLDPE copolymer with one comonomer and (ii) a plastomer having a density of less than 905 kg/m 3 ,
wherein the multimodal LLDPE copolymer and the plastomer are separate components; and
wherein said film is a stretched film which is uniaxially oriented in the machine direction (MD) in a draw ratio of at least 1:3 and has a film thickness of at least 40 microns after stretching and wherein said film does not comprise a layer in which more than 50 wt % of said layer comprises a polymer component having a melting point (Tm) of 100° C. or less.

2. A film as claimed in claim 1 wherein said HMW component is a terpolymer of ethylene, butene and hexene.

3. A film as claimed in claim 1 wherein layer (A) consists essentially of said multimodal LLDPE.

4. A film as claimed in claim 1 , wherein the film is not blocked.

5. A film as claimed in claim 1 , wherein the film is asymmetric.

6. A film as claimed in claim 1 , wherein the film has a thickness of 40 to 80 microns.

7. A film as claimed in claim 6 , wherein the film has an elmendorf tear resistance in the machine direction of at least 2.5 N.

8. A film as claimed in claim 6 , wherein the film has a dart drop of at least 450 g.

9. A film as claimed in claim 1 consisting of three layers.

10. A film as claimed in claim 1 consisting of layers (A), (B), and (C), wherein layer (C) comprises a multimodal LLDPE copolymer with one comonomer.

11. A process for the formation of a multilayer film as claimed in claim 1 comprising obtaining
a first polymeric component comprising a multimodal linear low density polyethylene (LLDPE) having a density of 905 to 935 kg/m 3 and an MFR 2 of 0.01 to 20 g/10 min which comprises a lower molecular weight (LMW) component and a higher molecular weight (HMW) component; wherein said LMW component is an ethylene homopolymer and said HMW component is an ethylene polymer of ethylene with at least two C4-12 alpha olefins; and
a second polymeric component comprising (i) at least 50 wt % of a multimodal LLDPE copolymer with one comonomer and (ii) a plastomer having a density of less than 905 kg/m 3 ,
wherein the multimodal LLDPE copolymer and the plastomer are separate components; and
extruding the first polymeric component and the second polymeric component to form a multilayer film, said film as a whole having a thickness of 240 microns or more wherein said film is not blocked;
uniaxially stretching said film in the machine direction (MD) in a draw ratio of at least 1:3 so as to form a film of at least 40 microns in thickness.

12. An article packaged using the film of claim 1 .

13. A film as claimed in claim 1 , wherein the plastomer has a density of less than 902 kg/m 3 .

14. A film as claimed in claim 1 , wherein the plastomer is from 10 wt % to 45 wt % of layer (B).

Assignees

• Borealis Ag

Inventors

• Nummila-Pakarinen Auli
• Niedersuess Peter

Classifications

• B32B2307/558

  Impact strength, toughness · CPC title

• B32B2439/70

  Food packaging · CPC title

• B32B2250/242

  All polymers belonging to those covered by group B32B27/32 · CPC title

• B32B27/32 Primary

  comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)} · CPC title

• B32B27/327

  comprising polyolefins obtained by a metallocene or single-site catalyst · CPC title