AU646144B2 - High abuse ionomer bag - Google Patents

Description

'144 646144

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): W. R. Grace Co.-Conn.

ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

INVENTION TITLE: High abuse ionomer bag S The following statement is a full description of this S invention, including the best method of performing it known to me/us:ee ee I 1 Page 1 The present invention relates to improvements in and/or relating to multilayer heat shrinkable plastic films, containers (eg bags) or packages using same and to related means and methods.

Multilayer heat shrinkable films have been used for some time for the shrink wrapping of various food products including meat products which will require refrigeration or freezing. Desirable characteristics in such films are their degree of shrinkage under moderate heat and their resistance to abuse.

Currently available in New Zeeland are several films useful in the wrapping of products such as meats. These include ionomer based materials, employed in ionomer bags of Trigon Packaging Systems (NZ) Limited of Corner Avalon Drive and Foreman Road, Hamilton, New Zeeland and the EVA (ethylenevinyl acetate copolymer) based materials of WR Grace (NZ) Limited of Prosser Street, Elsdon, Porirua, which are known as their SL3 and SB3 bags.

The abuse resistance of the films if improved would make such containers more useful in the packaging of products having a greater tendency to penetrate or puncture the packaging, such as meat cuts in which bones are retained. It is also desirable for films to have good resistance to external abuse.

It is also desirable for such films to be "high shrink" as this is important with respect to both presentation and consumer appeal.

S: In this regard, New Zeeland Patent Application No. 226 983 of WR Grace (NZ) Limited relates to multilyer films having both good resistance to abuse and heat shrinkability.

These films comprise at least three layers: two outside S layers, each comprising VLDPE (very low density polythylene) :or a blend of VLDPE/EVA, and an internal layer which is EVA or primarily EVA.

The present invention is related to films, containers, packages and methods of producing films, which will go some S. way towards meeting, at least in part, the above mentioned aims of good abuse resistance and heat shrinkability by choice.

As used herein, the term "VLDPE" refers to very low density polyethylene; "EVA" refers to an ethylene-vinyl acetate copolymer; "EMAA" refers to ethylene methacrylic acid copolymer, "EAA" to ethylene acrylic acid copolymer, "PVDC" to vinylidene chloride/vinyl chloride copolymer, and "MA" to vinylidene chloride methyl acrylate copolymer.

Page 2 Accordingly, in a first aspect the present invention may broadly be said to comprise a heat-shrinkable mul+4layer film having -t -aef resistance to abuse, comprisinc at least three layers, including: a) a first outside layer selected from the group comprising EVA, VLDPE and blends of VLDPE and EVA, b) a core or internal layer, comprising an ionomer or a blend thereof with EVA, EMAA or EAA, and c) a second outside layer selected from the group comprising EMAA, EAA and ionomers.

The core or internal layer b) preferably comprises either 1) sodium ionomer polymer alone, or 2) a blend of sodium ionomer polymer with EVA, comprising up to about 40% EVA, or 3) a blend of sodium ionomer polymer with EMAA or EAA, comprising up to about 25% of the EMAA or EAA.

For example, a blend of about 93% sodium ionomer polymer (specific gravity 0.94) with about 7% EVA (specific gravity 0.96), or a blend of about 95% sodium ionomer polymer with about 5% EMAA or EAA (specific gravity 0.93)/50% VLDPE (specific gravity 0.91).

The sencond outside layer is preferably a sealing layer, which in use will contact a product to be packaged by the film, and comprises either EMAA, EAA or sodium ionomer polymer.

The films of the present invention may also comprise an oxygen barrier layer, such as vinylidene chloride vinyl chloride copolymer, vinylidene chloride methyl acrylate copolymer, ethylene vinyl alcohol copolymer or polyamide, located between the first outside layer a) and the internal layer In addition, polymeric adhesive layers (eg EMAA) may S be included, between the first outside layer and the internal layer, or, if a barrier layer is included, between the barrier layer and the first outside layer and/or between the barrier layer and the internal layer b).

In a further aspect the present invention comprises a multilayer film having s ease! e=d resistance to abuse, comprising at least two layers, including: a) a first outside layer selected from the group comprising VLDPE, EVA and blends of VLDPE and EVA; and c) a second outside layer comprising EMAA.

I 1 1 Page 3 Preferably a core or internal layer b) is also included, which is preferably as hereinbefore described. Alternatively the core layer may comprise cross-linked EVA.

Preferably the first outside layer is as hereinbefore described.

Barrier and/or adhesive layers as hereinbefore described may also be included in this form of the present invention.

In a further aspect the present invention comprises a process of making a heat-shrinkable multilayer film, comprising: co-extruding as a multilayer film precursor laminate, at least three layers, including: a) a first outside layer selected from the group comprising EVA, VLDPE and blends of VLDPE and EVA, b) a core or internal layer, comprising an ionomer or a blend thereof with EVA, EMAA or EAA, and c) a second outside layer selected from the group comprising EMAA, EAA and ionomers; and (ii) subsequently treating the precursor to provide the multilayer film.

Preferably said precursor laminate is stretched by racking and/or blowing to a desired film thickness to thereby provide the heat shrinkable film.

Preferably said precursor laminate is stretched by first heating it to softening point, then expanding it by blowing a vertical bubble to stretch the laminate, cooling the laminate S into thin film, and collapsing the bubble onto converging rollers, then winding the film under tension into roll form.

Preferably said stretching is to about 5 to 9 times the S surface area of the film precursor.

o Preferably said precursor laminate has a total thickness of from about 400 microns to about 820 microns. Preferably said second outside layer c) of said precursor laminate has a thickness of about 75 to about 155 microns.

Preferably said core or internal layer b) of said precursor laminate has a thickness of from about 200 to about 410 microns.

o• Preferably said first outside layer a) of said precursor laminate has a thickness of from about 125 to about 255 microns.

I 1 1 Page 4 Preferably said multilayer film has a resultant total thickness of about 60 to about 120 microns.

In a further aspect the present invention comprises a process of making a mult 4 layer film, comprising: co-extruding as a multilayer film precursor laminate at least two layers, including: a) a first outside layer selected from the group comprising VLDPE, EVA and blends of VLLDPE and

EVA.

c) a second outside layer comprising EMAA; and (ii) subsequently treating the precursor to provide the multilayer film.

Preferably a core layer b) is also co-extruded with layers a) and c).

Preferably said multilayer film is as herein described.

The present invention will now be described in more detail, with reference to the accompanying drawings.

Figure 1 shows a three layer multilayer heat shrinkable film such as can be produced by extrusion, for convenience all film thicknesses being shown substantially identical. It will be appreciated that it is not essential that the film of the present invention has three layers from two to four or more layers may be used.

*Figure 2 is a diagrammatic view of a three-layer film.

In one preferred form of the present invention the multilayer film has three layers. Layer a) is preferably the so-called outside layer, which in use (when the film is used as a wrapping, or to define a container or package) will be that surface which does not contact the product. Layer c) is preferably the inner sealing layer, which in use will be that surface likely to contact the foodstuff. Layer b) is the core or internal layer.

Layer the inner sealing layer, may comprise EMAA, EAA, or an ionomer. EMAA is especially preferred, since use of EMAA copolymer provides the film with very good sealability properties, important when there may be contamination of the material, for example by particulates, and/or pleats or folds in the material. A layer c) of an ionomer also confers reasonably good sealability properties on the film, although a non-ionised form of EMAA is preferred in this respect.

Page Layer the core or internal layer, may comprise either an ionomer (preferably sodium ionomer polymer) or a blend thereof with EVA, EMAA or EAA. For example, the internal layer could comprise a blend of sodium ionomer polymer with up to about 10% EVA, more preferably up to 20% EVA, or a blend of sodium ionomer polymer with up to about 25% EAA or EMAA, more preferably from about 1% to about 10% by weight of EMAA or EAA. The ionomer provides the film with high shrink and high clarity properties. It is also possible for this layer to comprise some other heat-shrinkable material, such as crosslinked EVA. Layers c) and b) also give the film good resistance to internal puncturing.

Layer a) (the "outside layer"), in one preferred form of the invention, may be a blend of about 50% VLDPE with about of EVA copolymer, although blends of VLDPE and EVA containing up to about 70% EVA, or even EVA alone, may also be used. This layer provides the film with good external abuse resistance properties, while at the same time having a glossy appearance when shrunk, and a smooth printable surface finish.

It is also possible for there to be an additional layer, for example an oxygen barrier layer, to ensure that the film is substantially impermeable to gas transmission (mainly oxygen). The barrier layer could comprise any of the well known resins useful in enhancing oxygen barrier properties in a film or bag. These include vinylidene chloride vinylchloride copolymer, vinylidene chloride methyl arylate copolymer, ethylene vinyl alcohol copolymer and polyamide.

Adhesive layers may be used either to adhere the outside VLDPE/EVA layer to the core (preferably ionomer) layer, and/or S to adhere an oxygen barrier layer, such as PVDC or MA, to the other layers. Appropriate materials for adhesive layers which may be used include EVA, EMAA, EAA or ionomer. Possible structures which include the use of adhesive layers (with or without a barrier layer) may be: e a 6-layer structure:

VLDPE/EMAA/PVDC/EMAA/IONOMER/EMAA

a b c d e f a outside layer d adhesive layer S* b adhesive layer e internal layer c barrier layer f inner sealing layer or a 4-layer structure:

VLDPE/EMAA/IONOMER/EMAA

a b c d a outside layer b adhesive layer Sc internal layer d inner sealing layer In these structures, EAA may be used instead of EMAA.

I1

I

Page 6 Table 1 shows the structures of 3 different multilayer (three-layer) films made in accordance with the present invention.

TABLE 1: THE PACKAGING STRUCTURES STRUCTURE NO. 1 2 3 LAYER c) (inside) Resin (see below) A C C Thickness (micron) 90 90 Tolerance LAYER b) (core or internal) Resin (see below) A A D Thickness (micron) 235 235 235 Tolerance LAYER a) (outside) Resin (see below) B B B Thickness (micron) 145 145 145 Tolerance TOTAL THICKNESS OF PRECURSOR LAMINATE: (micron) 470 470 470 470 S Tolerance BLOW UP RATIO: 6.76 6.76 6.76 S RESULTANT FILM THICKNESS (micron): 80 80 Tolerance

RESINS:

A SODIUM IONOMER POLYMER, specific gravity (sg) 0.94 B Blend of 50% by weight of Very Low Density Polyethylene (VLDPE), sg 0.91, with 50% of Ethylene Vinyl Acetate (EVA) Copolymer, sg 0.93.

C Ethylene Methacrylic Acid Copolymer (EMAA), sg 0.94.

D Blend of 93% of Sodium lonomer Polymer, sg 0.94, with 7% of EVA copolymer, sg 0.96.

'i Page 7 are: The general properties of the final packaging structure a. Percent Shrink at LD (longitudinal direction) 35 to TD (transverse direction) 50 to b. Tensile Strengh in kg/sq cm: LD 400 to 550 TD 400 to 600 c. Percent Elongation: LD 120 to 180 TD 150 to 250 The packaging performance characteristics of each layer in each structure are dependent on the resins being used.

These characteristics may be generalised as follows: STRUCTURE 1: Layers c) and b) Layer a) STRUCTURE 2: a a a 6 oo o* Easy sealability through contamination and pleats.

High clarity and high shrink.

Good resistance to internal puncturing.

Glossy appearance when shrunk.

Good resistance to external abuse puncturing.

Smooth printable surface finish.

Easy sealability at low temperature through contamination and pleats.

High clearity.

Good resistance to internal puncturing.

High clarity and high shrink.

Good resistance to internal puncturing.

Same as Structure 1.

Layer c) Layer b) Layer a) STRUCTURE 3: Layer c) Layer b) Layer a) Same as Structure 2.

Same as Structure 2.

Same as Structure 1.

I 'I Page 8 Table 2 shows examples of alternative structures of multi-layer films in accordance with the present invention, in which layer a) (outside layer) comprises EVA copolymer alone.

In these structures, layer c) (the inside sealing layer) comprises EMAA or EAA (specific gravity 0.94); layer b) (the core layer) comprises sodium ionomer blended with EMAA or EAA at a ratio of 5% by weight of EMAA or EAA (ionomer specific gravity 0.94); and layer a) (the outside layer) comprises EVA copolymer (specific gravity 0.96).

Table 2: Further Packaging Structures Structure No. 4 5 6 7 Layer c) (inside) Resin (see below) C C D D Thickness (micron) 90 90 90 Tolerance Layer b) (core) Resin (see below) E G E G Thickness (micron) 200 200 200 200 Tolerance Layer a) (outside) Resin (see below) F F F F Thickness (micron) 180 180 180 180 Tolerance S Total thickness S of precursor laminate (micron) 470 470 470 470 S: Tolerance Blow Up Ratio 6.76 6.76 6.76 6.76 Resultant film thickness (micron) 80 80 80 Tolerance

RESINS:

C Ethylene Methacrylic Acid Copolymer (EMAA), sg. 0.94 D Ethylene Acrylic Acid Copolymer (EAA), sg. 0.94 E Blend of 95% sodium ionomer polymer with 5% EMAA copolymer (ionomer sg. 0.94) F EVA copolymer G Blend of 95% sodium ionomer polymer with 5% EAA copolymer, sg. 0.94 Page 9 The precursor laminates may be made by using a three layer coextrusion process examples of the resins and peferrz'd layer thicknesses are specified in Tables 1 and 2.

The thicknesses of the various layers are chosen so as to provide an overall multilayer film thickness that is desired.

The total thickness of the precursor laminate is preferably in the range of about 400 to 820 microns.

After the precursor laminate has been formed, it is oriented by first heating it to softening point, then expanding it by blowing a vertical bubble. This stretches the laminate into a thin film which is cooled. The bubble is collapsed by converging rollers then wound under tension into roll form. In this regard, Figure 2 shows how the precursor laminate is to be blown down to film, Alternatively, tenter frame stretching may be used to stretch the precursor laminate.

The stretching process orientates the polymer molecules into longitudinal and transverse directions (LD and TD). The amount of stretch is the Blow Up Ratio which is specified in Table 1. The preferred Blow Up Ratio is about 6.76. The total thickness of the final film (after coextrusion and orientation) is preferably from about 60 to 120 microns.

o: Other processes known in the art such as extrusion coating, and conventional lamination, may also be used to make •the precursor laminates.

Optionally, when the inner sealing layer comprises EMAA or EAA, and the core layer is not a ionomer (eg when the core layer comprises EVA) the sealing layer, the core layer, and any additional layers located between the core and sealing layers, may be cross-linked, using, for example, irridation.

It is believed that a multilayer film in accordance wit.).

the present invention will provide a multilayer film having good abuse resistance properties, both to internal and external puncturing (due to the presence of a layer comprising a blend of VLDPE/EVA or EVA), while at the same time having good heat shrinkability, high clarity and good sealability.

Percentages used throughout the description and claims are percentages by weight.

Claims (54)

1. A heat-shrinkable multilayer film having a=meatme=f resistance to abuse, comprising at least three layers, including: a) a first outside layer selected from the group comprising EVA, VLDPE and blends of VLDPE and EVA, b) a core or internal layer, comprising an ionomer or a blend thereof with EVA, EMAA or EAA, and c) a second outside layer selected from the group comprising EMAA, EAA and ionomers.

2. A multilayer film as claimed in claim 1 wherein the core or internal layer b) comprises a blend of sodium ionomer polymer with EMAA copolymer, and wherein the blend comprises from about 0% to 25% EMAA copolymer.

3. A multilayer film as claimed in claim 1 or 2, wherein the core or internal layer b) comprises a blend of about sodium ionomer polymer with about 5% EMAA copolymer.

4. A multilayer film as claimed in claim 1, wherein the core or internal layer b) comprises a blend of a sodium S. ionomer polymer with EAA copolymer, and wherein the blend comprises from about 0% to 25% EAA copolymer.

5. A multilayer film as claimed in claim 1 or 4 wherein the core or internal layer b) comprises a blend of about sodium ionomer polymer with about 5% EAA copolymer.

6. A multilayer film as claimed in claim 1, wherein the core or internal layer b) comprises a blend of a sodium ionomer polymer with EVA, and wherein the blend comprises from about 0% to 40% EVA. S

7. A multilayer film as claimed in claim 1 or 6, wherein the core or internal layer b) comprises a blend of about 93% sodium ionomer polymer with about 7% EVA copolymer.

8. A multilayer film as claimed in claim 1, wherein the core or internal layer b) comprises sodium ionomer polymer alone.

9. A multilayer film as claimed in any one of the claims 2 to 8 wherein said sodium ionomer polymer has a specific gravity of about 0.94, and said EVA has a specific gravity of about 0.96. A multilayer film as claimed in any preceding claim wherein the first outside layer a) comprises a blend of VLDPE and EVA, and wherein said blend comprises from AigA about 0% to 70% EVA. Page 11

11. A multilayer film as claimed in claim 10 wherein the first outside layer a) comprises a blend of about 50% by weight VLDPE and about 50% by weight of EVA.

12. A multilayer film as claimed in any one of claims 1 to 9 wherein the first outside layer a) comprises EVA alone.

13. A multilayer film as claimed in any one of claims 1 to 11 wherein said VLDPE has a specific gravity of about 0.91.

14. A multilayer film as claimed in any one of claims 1 to 13 wherein said EVA of said first outside layer has a specific gravity of about 0.93. A multilayer film as claimed in any one of the preceding claims wherein the second outside layer c) is a sealing layer which in use will contact a product to be packaged by the film.

16. A multilayer film as claimed in claim 15 wherein the sealing layer c) comprises EMAA.

17. A multilayer film as claimed in claim 15 wherein the sealing layer c) comprises EAA.

18. A multilayer film as claimed in any one of the preceding claims wherein the EMAA or EAA has a specific gravity of about 0.94. S: 19. A multilayer film as claimed in claim 15 wherein the sealing layer comprises a sodium ionomer polymer.

20. A multilayer film as claimed in any preceding claim which further includes an oxygen barrier layer located between the first outside layer a) and the internal layer b).

21. A multilayer film as claimed in claim 20 wherein the %00' barrier layer comprises PVDC or MA.

22. A multilayer film as claimed in any one of the claims 1 to 19 which further includes an adhesive layer between the first outside layer a) and the internal layer b).

23. A multilayer film as claimed in claim 20 or 21 which further includes one or more adhesive layers between the barrier layer and the first outside layer and/or between the barrier layer and the internal layer b).

24. A multilayer film having f resistance to abuse, comprising at least two layers, including: a) a first outside layer selected from the group comprising VLDPE, EVA and blends of VLDPE and EVA; and S1 Page 12 b) a second outside layer comprising EMAA. A multilayer film as claimed in claim 24, further including a c.re or internal layer b).

26. A multilayer film as claimed in claim 25, wherein the core or internal layer b) comprises a blend of a sodium ionomer polymer with EMAA copolymer, and wherein the blend comprises from about 0% to 25% EMAA copolymer.

27. A multilayer film as claimed in claim 25 or 26, wherein the core or internal layer b) comprises a blend of about sodium ionomer polymer with about 5% EMAA copolymer.

28. A multilayer film as claimed in claim 25, wherein the core or internal layer b) comprises a blend of a sodium ionomer polymer with EAA copolymer, and wherein the blend comprises from about 0% to 25% EAA copolymer.

29. A multilayer film as claimed in claim 25 or 28, wherein the core or internal layer b) comprises a blend of about sodium ionomer polymer with about 5% EMAA copolymer. A multilayer film as claimed in claim 25, wherein the core or internal layer b) comprises a blend of a sodium ionomer polymer with EVA, and wherein the blend comprises from about 0% to 40% EVA.

31. A multilayer film as claimed in claim 25 or 30, wherein the core or internal layer b) comprises a blend of about 93% sodium ionomer polymer with about 7% EVA copolymer.

32. A multilayer film as claimed in claim 25, wherein the core or internal layer b) comprises sodium ionomer polymer alone. I* 33. A multilayer film as claimed in any one of claims 26 to S: 32, wherein said sodium ionomer polymer has a specific S.:gravity of about 0.94, and said EVA has a specific gravity of about 0.96.

34. A multilayer film as claimed in claim 25, wherein said internal layer b) comprises cross-linked EVA. i 35. A multilayer film as claimed in claim 25, wherein the first outside layer a) comprises a blend of VLDPE and EVA, and wherein said blend comprises from about 0% to EVA.

36. A multilayer film as claimed in claim 35, wherein the first outside layer a) comprises a blend of about 50% by weight VLDPE and about 50% by weight EVA.

37. A multilayer film as claimed in any one of claims 25 to 34 wherein the first outside layer a) comprises EVA alone. Page 13

38. A multilayer film as claimed in any one of claims 25 to 36 wherein said VLDPE has a specific gravity of about 0.91.

39. A multilayer film as claimed in any one of claims 25 to 38 wherein said EVA of said first outside layer has a specific gravity of about 0.93. A multilayer film as claimed in any one of claims 24 to 39, wherein the second outside layer c) is a sealing layer, wich in use will contact a product to be packaged by said film.

41. A multilayer film as claimed in any one of claims 24 to wherein said EMAA has a specific gravity of about 0.94.

42. A multilayer film as claimed in any one of claims 25 to 41 which further includes an oxygen barrier layer located between the first outside layer a) and the internal layer b).

43. A multilayer film as claimed in claim 42 wherein the barrier layer comprises PVDC or MA.

44. A multilayer film as claimed in any one of claims 25 to 41 which further includes an adhesive layer between the first outside layer a) and the internal layer b).

45. A multilayer film as claimed in claim 42 or 43 which further includes one or more adhesive layers between the barrier layer and the first outside layer and/or •between the barrier layer and the internal layer b).

46. A process of making a heat-shrinkable multilayer film, o comprising: co-extruding as a multilayer film precursor laminate, at least three layers, including: a) a first outside layer selected from the group comprising EVA, VLDPE and blends of VLDPE and EVA, b) a core or internal layer, comprising an ionomer or a blend thereof with EVA, EMAA or EAA, and S" c) a second outside layer selected from the group comprising EMAA, EAA, and ionomers, and (ii) subsequently treating the precursor to provide the multilayer film.

47. A process as claimed in claim 46 wherein said precursor laminate is stretched by racking and/or blowing to a desired film thickness to thereby provide the multilayer film. '1 11 Page 14

48. A process as claimed in claim 47 wherein said stretching is to about 5 to 9 times the surface area of the film precursor.

49. A process as claimed in any one of claims 46 to 48 wherein said precursor laminate has a total thickness of from about 400 to about 820 microns. A process as claimed in any one of claims 46 to 49 wherein said layer c) of said precursor laminate has a thickness of about 75 to about 155 microns.

51. A process as claimed in any one of claims 46 to whereir. said layer b) of said precursor laminate has a thickness of about 200 to about 410 microns.

52. A process as claimed in any one of claims 46 to 51 wherein said layer a) of said precursor laminate has a thickness of about 125 to about 255 microns.

53. A process as claimed in any one of claims 46 to 52 wherein said multilayer film has a resultant total thickness of about 60 to about 120 microns.

54. A multilayer film as claimed in any one of claims 1 to 23 when produced by a process as claimed in any one of claims 46 to 53. A process of making a multilayer film comprising: co-extruding as a multilayer film precursor laminate at least two layers, including: a) a first outside layer selected from the group comprising VLDPE, EVA and blends of VLDPE and EVA, c) a second outside layer comprising EMAA; and (ii) subsequently treating the precursor to provide the multilayer film.

56. A process as claimed in claim 55 wherein a core or internal layer b) is co-extruded with layers a) and c) to form the multilayer film precursor laminate, said layer b) comprising either cross-linked EVA or an ionomer or a blend thereof with EVA, EMAA or EAA.

57. A process as cla4-ed in claim 55 or 56 wherein said precursor laminate is stretched by racking and/or blowing to a desired film thickness to thereby provide the heat- shrinkable film.

58. A process as claimed in any one of claims 55 to 57 wherein said stretching is to about 5 to 9 times the surface area of the film precursor. I I ij Page

59. A process as claimed in any one of claims 56 to 58 wherein said precursor laminate has a total thickness of from about 400 to about 820 microns. A process as claimed in any one of claims 56 to 59 wherein said layer c) of said precursor laminate has a thickness of from about 75 to about 155 microns.

61. A process as claimed in any one of claims 56 to wherein said layer b) of said precursor laminate has a thickness of about 200 to about 410 microns.

62. A process as claimed in any one of claims 56 to 61 wherein said layer a) of said precursor laminate has a thickness of about 125 to about 255 microns.

63. A process as claimed in any one of claims 55 to 62 wherein said multilayer film has a resultant total thickness of about 60 to about 120 microns.

64. A multilayer film as claimed in any one of claims 24 to when produced by a process as claimed in any one of claims 55 to 63. A multilayer film substantially as herein described with S. reference to the examples and/or the accompanying drawings.

66. A process of making a multilayer film substantially as o herein described with reference to the examples and/or the accompanying drawings. herein or referred to or indicate i ication and/or claims of ion, individually or R and any and all combinations of any two or DATED this TWENTY THIRD day of APRIL 1992 W. R. Grace Co. -Conn. by DAVIES COLLISON CAVE Patent Attorneys for the applicant(s) Page 16 ABSTRACT A heat-shrinkable multilayer film having a measure of resistance to abuse, comprising at least three layers, including: a) a first outside layer selected from the group comprising EVA, VLDPE and blends of VLDPE and EVA, b) a core or internal layer, comprising an ionomer or a blend thereof with EVA, EMAA or EAA, and c) a second outside layer selected from the group comprising EMAA, EAA, and ionomers. *4* 0# oC C at