PRE-STRETCHED MULTI-LAYER STRETCH FILM

• US 20090269566A1
• Filed: 04/22/2009
• Published: 10/29/2009
• Est. Priority Date: 04/23/2008
• Status: Abandoned Application

• Current Assignee: Berry Plastics Corporation (Berry Global Group Inc.)
• Original Assignee: Berry Plastics Corporation (Berry Global Group Inc.)
• Inventors: Eichbauer, George N., Tukachinsky, Alexander
• Application Number:
  US12/428,345
• Publication Number:
  US 20090269566A1
• Time in Patent Office: Days
• US Class Current: 428/220
• CPC Class Codes: B32B 2270/00 Resin or rubber layer containing a blend of at least two different polymers
• CPC Class Codes: B32B 2307/50 having particular mechanical properties
• CPC Class Codes: B32B 2307/514 Oriented
• CPC Class Codes: B32B 2307/54 Yield strength; Tensile strength
• CPC Class Codes: B32B 2307/5825 Tear resistant
• CPC Class Codes: B32B 2307/704 Crystalline
• CPC Class Codes: B32B 2307/72 Density
• CPC Class Codes: B32B 2553/00 Packaging equipment or accessories not otherwise provided for
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/16 specially treated, e.g. irradiated
• CPC Class Codes: B32B 27/18 characterised by the use of special additives
• CPC Class Codes: B32B 27/308 comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/327 comprising polyolefins obtained by a metallocene or single-site catalyst
• CPC Class Codes: B32B 7/03 with respect to the orientation of features direction of fibres or filaments B32B5/12
• CPC Class Codes: B32B 7/035 using arrangements of stretched films, e.g. of mono-axially stretched films arranged alternately
• CPC Class Codes: Y10T 428/31913 Monoolefin polymer

Abstract

A multi-layer stretch film includes multiple layers of polyolefins. A multi-layer stretch film may include two or more layers including a cling layer, a non-cling layer, or a core layer. A multi-layer stretch film includes a pre-stretched multi-layer stretch film having two or more layers.

Claims

1. A pre-stretched multi-layer stretch film comprising

a cling layer, a non-cling layer, and a core layer interposed between the cling layer and the non-cling layer, wherein, the pre-stretched multi-layer stretch film has a gauge normalized puncture resistance greater than about two times the gauge normalized puncture resistance of an input film from which the pre-stretched multi-layer stretch film was derived.

2. The pre-stretched multi-layer stretch film of claim 1, wherein the core layer comprises a composition that resists row-nucleated microcrystalline orientation via rapid molecular relaxation.

3. The pre-stretched multi-layer stretch film of claim 1, wherein the core layer comprises a blend of LLDPE having a first MI of less than or about equal to 2.

4. The pre-stretched multi-layer stretch film of claim 3, wherein the blend of LLDPE includes about 80% to about 100% LLDPE having a second MI of less than or about equal to 1 and about 0% to about 20% LLDPE having a third MI of less than or about equal to 2.5.

5. The pre-stretched multi-layer stretch film of claim 3, wherein the blend of LLDPE includes about 90% LLDPE having a second MI of less than or about equal to 1 and about 10% LLDPE having a third MI of less than or about equal to 2.5.

6. The pre-stretched multi-layer stretch film of claim 5, wherein the non-cling layer comprises about 35% LDPE.

7. The pre-stretched multi-layer stretch film of claim 3, wherein the non-cling layer comprises from about 10% to about 50% LDPE, wherein the LDPE has a fourth MI of about 4 to about 8.

8. The pre-stretched multi-layer stretch film of claim 7, wherein the cling layer comprises an EMA copolymer.

9. The pre-stretched multi-layer stretch film of claim 7, wherein the cling layer comprises a blend LLDPE with a tackifier selected from an elastomer and a plastomer.

10. The pre-stretched multi-layer stretch film of claim 1, wherein the core layer is substantially free of a strain hardened polymer.

11. The pre-stretched multi-layer stretch film of claim 10, wherein the non-cling layer comprises from about 10% to about 50% of the strain hardened polymer.

12. The pre-stretched multi-layer stretch film of claim 1, wherein the core layer is substantially free of LDPE.

13. The pre-stretched multi-layer stretch film of claim 1, wherein the pre-stretched multi-layer stretch film has a gauge normalized puncture resistance of greater than or about 450 g/mil as determined by ASTM D-1709.

14. A pre-stretched multi-layer stretch film comprising a first exterior layer, a second exterior layer, and a core layer interposed between the first exterior layer and the second exterior layer, wherein, the first exterior layer has a first microcrystalline orientation and the core layer has a second microcrystalline orientation.

15. The pre-stretched multi-layer stretch film of claim 14, wherein the first microcrystalline orientation includes a row-nucleated microcrystalline orientation and the second microcrystalline orientation includes a microcrystalline orientation selected from a group consisting of spherulite-like or elongated spherulite-like.

16. The pre-stretched multi-layer stretch film of claim 15, wherein the first exterior layer comprises from about 10% to about 50% of a strain hardened polymer.

17. The pre-stretched multi-layer stretch film of claim 15, wherein the first exterior layer comprises a blend of LDPE and LLDPE.

18. The pre-stretched multi-layer stretch film of claim 17, wherein the blend of LDPE and LLDPE comprises about 35% LDPE and about 65% LLDPE by weight.

19. The pre-stretched multi-layer stretch film of claim 17, wherein the core layer is substantially free of LDPE.

20. The pre-stretched multi-layer stretch film of claim 14, wherein the pro-stretched multi-layer stretch film has a gauge normalized puncture resistance of greater than or about 450 g/mil as determined by ASTM D-1709.

21. A pre-stretched multi-layer stretch film comprising a first layer having a spherulite-like microcrystalline orientation and a second layer having a row-nucleated microcrystalline orientation, wherein the pre-stretched multi-layer stretch film has a gauge normalized puncture resistance greater than about 450 g/mil as determined by ASTM D-1709.

22. A pre-stretched multi-layer stretch film of claim 21, wherein the pre-stretched multi-layer stretch film includes about 80 to about 93% LLDPE, about 5 to about 8% LDPE, and about 2 to about 15% a cling promoting polymer.

23. The pre-stretched multi-layer stretch film of claim 22, wherein the cling promoting polymer is selected from a group consisting of an elastomer, a plastomer, and an EMA copolymer.

24. The pre-stretched multi-layer stretch film of claim 22, wherein the pre-stretched multi-layer stretch film is from about 0.10 mil to about 0.80 mil in thickness.

25. The pre-stretched multi-layer stretch film of claim 21, wherein the first layer includes less than 1% of a strain hardened polymer.

26. The pre-stretched multi-layer stretch film of claim 25, wherein the second layer includes about 10 to about 50% of the strain hardened polymer.

27. The pre-stretched multi-layer stretch film of claim 21, wherein the pre-stretched multi-layer stretch film is a pre-stretched machine-wrap film having an initial modulus and a later modulus after being stretched by about 50 to about 200%, wherein the later modulus is 50% greater than the initial modulus.

28. The pre-stretched multi-layer stretch film of claim 21, wherein the pre-stretched multi-layer stretch film is a pre-stretched band-wrap film having an initial modulus and a later modulus after being stretched by about 25 to about 50%, wherein the later modulus is 50% greater than the initial modulus.