WO2009049418A1

WO2009049418A1 - Abrasion resistant thermoplastic film

Info

Publication number: WO2009049418A1
Application number: PCT/CA2008/001834
Authority: WO
Inventors: Julien Lefebvre; Ludovic Capt; Jose Garrocho; Roger Tambay
Original assignee: Marko I.R.D.C. Inc.
Priority date: 2007-10-15
Filing date: 2008-10-15
Publication date: 2009-04-23

Abstract

The present invention provides an abrasion resistant thermoplastic film that is elastomeric. The film of the present invention comprises two or more layers, wherein at least one of the layers is elastomeric and at least one of the layers is non-elastomeric. Preferably, abrasion resistance is further improved by incorporating an anti-skid agent in one or more layers of the film. The film is useful for industrial packaging, for example, with automatic wrapping machines, but can be used to wrap any product for shipping or storage. The present invention also provides methods of manufacturing the abrasion resistant thermoplastic films.

Description

ABRASION RESISTANT THERMOPLASTIC FILM

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority from U.S. provisional patent application No. 60/980,035, filed October 15, 2007, the content of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention pertains to the field of thermoplastic films and, more particularly, to the field of abrasion resistant elastømeric thermoplastic.

BACKGROUND

Stretch plastic film has gained substantial acceptance for use in the lumber industry and in warehouse packaging applications where plastic film is stretched around containers, lumber, palletized loads, or irregular loads, with the built-in elastic recovery properties of the film constraining the surrounded item(s). Automatic wrapping machines are often employed with such films. A number of polymeric materials, such as polyvinyl chloride (PVC), linear low- density polyethylene (LLDPE), low density polyethylene (LDPE), and ethylene vinyl acetate copolymers (EVA), low density polyethylene (LDPE), polyolefin plastomers (POP) are used to produce stretch film for commercial use. Such films can comprise multiple layers.

When employing thermoplastic films in wrapping applications, it has been found that abrasions in the films can be caused by, for example, excessive friction from watershield curtains, lift truck forks, and strapping used to secure wrapped loads during transportation. There remains a need for an elastomeric thermoplastic film that is abrasion resistant. This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present application. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present application.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an abrasion resistant thermoplastic film In accordance with an aspect of the present invention, there is provided an abrasion resistant, elastomeric film comprising two or more layers, wherein at least the outer layer of the film is non-elastomeric. In accordance with another aspect of the present invention, there is provided an elastomeric film comprising: an outer layer that is non-elastomeric and provides increased abrasion resistance in said elastomeric film as compared to the abrasion resistance of an elastomeric film that does not include the non-elastomeric layer; and at least one elastomeric layer. In accordance with another aspect of the present invention, there is provided a method of manufacturing an elastomeric film with improved abrasion resistance comprising: combining a noπ-elastomeric layer with at least one elastomeric layer such that the non- elastomeric layer becomes the outer layer of the elastomeric film, wherein the abrasion resistance of said elastomeric film is improved in comparison to an elastomeric film that does not include a non-elastomeric outer layer.

In accordance with another aspect of the present invention, there is provided a method of improving the abrasion resistance of an elastomeric film comprising; adding about 0.1 % - about 20% by weight of an anti-skid additive to a mixture used to prepare a layer of said elastomeric film, wherein said weight percent is based on the total weight of said mixture. In accordance with another aspect of the present invention, there is provided a use of an anti-skid agent to improve the abrasion resistance of an elastomeric film. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 graphically depicts the comparative results of slip testing of two anti-skid containing films under dry conditions.

Figure 2 graphically depicts the comparative results of slip testing of two anti-skid containing films under wet conditions.

Figure 3 graphically depicts the film/wood coefficients of friction determined for various films under wet and dry conditions.

DETAILED DESCRIPTION OF THE INVENTION

Following experimentation with thermoplastic films, it has surprisingly been found that if at least one of the polymer layers of a bilayer or multi-layer film is made of an elastomeric material, and at least one outer layer is made of a non-elastomeric material, the resulting film has improved abrasion resistance in comparison to standard stretch films, and exhibits an elasticity only marginally less than that of films comprised entirely of elastomeric layers. Optionally, the film of the present invention is transparent (or clear) or semi- transparent.

Furthermore, it has also been surprisingly found that the incorporation of anti-skid additive to a layer of an elastomeric film, preferably at least the outer layer, improves the abrasion resistance of the film in comparison to elastomeric films that do not include antiskid additive. This finding has been observed in elastomeric films that do not contain non- elastomeric layers and those that do contain non-elastomeric layers.

The thermoplastic film of the present invention comprises two or more polymer layers. At least one layer of the film is elastomeric and at least the outer layer is non- elastomeric. The purpose of the non-elastomeric layer is to impart improved abrasion and, optionally, heat resistance to the film without unduly compromising the elastic properties of the film as a whole. As used herein, "abrasion resistant" films are those that exhibit improved abrasion resistance in comparison to standard stretch films (i.e., elastomeric films) that do not contain a non-elastomeric layer and/or an anti-skid additive. In a specific embodiment of the present invention, the film comprises three layers. The three layers are referred to herein as Layer A₅ the outside or outer layer, Layer B, the middle layer, and Layer C, the inside layer intended to be closest to the material to be wrapped. The film is manufactured with Layer A and Layer C as non-elastomeric layers, and Layer B as an elastomeric layer.

In another specific embodiment of the present invention, the film comprises two layers. The two layers are referred to herein as Layer A, the outside or outer layer, and Layer C, the inside layer intended to be closest to the material to be wrapped. The film is manufactured with Layer A as a non-elastomeric layer, and Layer C as an elastomeric layer. Components of the Film

Resins

The compositions from which the layers of the film of the present invention are manufactured comprise one or more resin components selected from, for example: a linear low density polyethylene (LLDPE); a polyolefin plastomer (POP); a medium density polyethylene (MDPE), an ethylene- vinyl acetate (EVA), low density polyethylene (LDPE), high density polyethylene (HDPE), and low density polypropylene (LDPP). The selection of the appropriate resins or resin mixture is made based on the desired elastomeric or non- elastomeric properties of the layers, as well as the ultimate application of the film.

In accordance with the present invention, the resins are chosen such that one or more layers is elastomeric, and one or more layers is non-elastomeric.

As used herein with reference to the elastomeric properties of the film or film layers, the term "non-elastomeric" is used to refer to a film, or film layer, in which the density of the resin or resin blend is 0.925 g/cm³ or higher. As used herein with reference to the elastomeric properties of the film or film layers, the term "elastomeric" is used to refer to a film, or film layer, in which the density of the resin or resin blend is less than 0.925 g/cm³ and is preferably 0.918 g/cm³ or less. The density of the resin or resin blend is determined excluding any contribution from additives. Since the film of the present invention is elastomeric, the combined density of the resin blends used to prepare the component layers is less than 0.925 g/cm³, or preferably 0.918 g/cm³ or less. Resins useful in forming non-elastomeric film layers have a density of 0.925 g/cm³ Of higher. Specific examples of suitable resins include, but are not limited to, metallocene based medium density polyethylene (e.g., Total M3490 (density = 0.934, melt index = 0.9), advanced zeigler-natta catalyzed LLDPE (e.g., Westlake Hifor™ SC-74350X (density = 0.926, melt index = 0.6), medium or high density polyethylene (e.g., DOW XUS 59000.82 (density = 0.940)) and combinations thereof.

Resins useful in forming elastomeric film layers have a density of less than 0.925 g/cm³, or, more preferably, 0.918 g/cm^J or less. Specific examples of suitable resins include, but are not limited to, mixed catalyzed LLDPE (e.g., Nova FP-112 (density = 0.912, melt index= 0.8), advanced zeigler-natta catalyzed LLDPE (e.g., Westlake Mxsten™(density = 0.905, melt index = 0.6) or Dow Attane™ 4201 (density - 0.905, MI=I .0)), metallocene catalyzed LLDPE (e.g., Dow Affinity™ PL188O (density = 0.902, melt index = LO)), metallocene catalyzed PP (e.g., Dow Versify™ 3400 (density = 0,902, melt index = 1.0)), EVA (e.g., Exxon Elvax™ ) and combinations thereof

Anti-skid Additives

In accordance with a specific embodiment of the present invention, one or more layers of the film includes an anti-skid additive. As used herein, the term "anti-skid additive" refers to an additive that has a particle size between 50 and 1000 microns and that either does not melt under film processing conditions or melts under film processing conditions but does not mix with the remaining film components such that upon cooling anti-skid particles are formed or reformed. The material from which the anti-skid additive is prepared is not critical, provided that the additive is capable of appropriate dispersion within the film. An anti-skid additive that exhibits appropriate dispersion within the film is one that exhibits good mixing properties and does not spontaneously agglomerate under film processing conditions. Preferably, the anti-skid additive has a particle size of between 50 and 700 microns, and more preferably, the anti-skid additive has a particle size of between 50 and 500 microns. In this most preferred range, it has been observed that the formation of micro-perforations in the film is minimized or avoided altogether.

Examples of suitable anti-skid additives include, but are not limited to, sand, clay, silica, cross-linked polyethylene, ultra high molecular weight polyethylene (UHMWPE) or other polymers. Within this class of anti-skid additives a sub-class of suitable anti-skid additive has a relatively narrow particle size distribution, which is advantageously between 60 and 250 microns, or more specifically, between 60 and 180 microns, and a high molecular weight (usually with a melt index below 0.1 g/10 min). In one embodiment of the present invention the anti-skid additive consists of an ultra high molecular weight polyethylene (UHMWPE) powder having a melt point of at least 500 ⁰F and a particle size ranging from 50 to 500 microns. The UHMWPE is optionally produced using a cross-linking process. Specific examples of suitable, commercially available antiskid additives of this type include Ampacet™ 10820, Spartech™ ASl 8411, Spartech™ 2490 and A. Schulman™ MAS-25.

In use, the anti-skid additive is usually provided in a high content masterbatch, comprising 25 - 85% anti-skid additive by weight Advantageously, the anti-skid masterbatch comprises greater than 50% anti-skid additive by weight; typically between 50 - 70%.

When an anti-skid masterbatch is employed, the composition used to manufacture one or more layers of the film contains between 1 and 30% of anti-skid masterbatch such that the final concentration of anti-skid additive is 0.1 to 20% by weight in the one or more layers.

In an alternative embodiment, when an anti-skid additive is used in pure form rather than in a masterbatch, the anti-skid additive is provided at a final concentration of 0.1 to 20% by weight in one or more layers of the film. Preferably, the final concentration of anti-skid additive is in the range of about 0.3 to about 10% by weight in one or more layers. It is in this range that the an improved abrasion resistance is most notable; although it is also observed at the lower and higher concentrations.

Jn accordance with one aspect of the present invention there is provided a method of using an anti-skid additive to modify an elastomeric film's surface to improve the film's abrasion resistance. The method comprises the step of adding an anti-skid additive, as defined herein, to the mixture used to prepare one or more layers of an elastomeric film. Advantageously, the anti-skid additive is present in the outer layer of the film. The method optionally includes the step of adding an anti-skid additive to the mixture used to prepare the inner layer of an elastomeric film. In this embodiment, the film additionally includes at least one middle layer that does not include an anti-skid additive. The elastomeric film manufacture by this method may or may not contain include a non-elastomeric layer.

In one embodiment of this invention, the manufactured film includes an elastomeric outer layer A comprising anti-skid additive and an elastomeric inner layer C comprising anti- skid additive. In this embodiment, the abrasion resistance properties of the film are improved by the presence of the anti-skid additive in both the outer and inner layers of the film. It has been surprisingly found that stacked bundles of lumber wrapped in a film having this configuration exhibit improved abrasion resistance with increasing amounts of anti-skid additive. In particular, movement of the stacked bundles using forklifts resulted in less abrasion related damage to the films having the higher anti-skid additive levels.

Other Additives

One or more layers of the film of the present invention can include one or more additives useful in packaging films, such as, but not limited to, a pigment, a slip agent, an anti-static agent, an anti-fog agent, an antioxidant, a heat stabilizer, a filler, a radiation stabilizer (e.g., a UV stabilizer (inhibitor)) and/or an anti-blocking agent. Such additives, and their effective amounts, are known in the art, however, typical additive master batch loading amounts are in the range of 0.1% to 5% by weight based on the layer of the film containing the additive.

In accordance with a specific embodiment of the present invention, one or more layers of the film includes a hindered amine light stabilizer as a UV inhibitor.

In accordance with another embodiment of the present invention, one or more layers of the film includes an anti-blocking agent that is calcium carbonate, talc or silica. In accordance with a specific example of the present invention, one or more layers of the film comprises 10 % calcium carbonate, In accordance with another embodiment of the present invention, one or more layers of the film includes an anti-static agent that is ethoxylated amine or dodecanamide.

In accordance with another embodiment of the present invention, one or more layers of the film includes an anti-skid agent that is a polymeric or an inorganic cluster material. In accordance with another embodiment of the present invention, one or more layers of the film includes a slip agent that is oleamide, erucamide or stereamide.

Fn accordance with another embodiment of the present invention, one or more layers of the film includes a anti-fog agent. In accordance with one embodiment of the present invention, a mineral filler agent such a caJcium carbonate, calcium sulfate, talc, wollastonite, silica, glass fibre and the like is added to a pigmented film in order to decrease the appearance of stretch marks by minimizing the discolouration of the film when stretched (see for example PCT/CA2007/001211, which is incorporated herein by reference). In accordance with another embodiment of the present invention, pigments and other opaque additives, including mineral filler agents, are not included in any layer of the film so that the film is transparent.

Manufacture of Film

The film of the present invention can be manufactured by a variety of processes known in the art. For example, the film can be a blown film, a cast film, or can be prepared by adhering one or more flat film to another flat film (where the films are made by blowing or casting). These processes are well-known to those of skill in the art.

The film can be oriented in the machine direction or alternatively it can be biaxially oriented by methods that are well-known to those of skill in the art. For example, the film can be oriented in the machine direction by employing heated rollers. The film can be biaxially oriented by making a thick cast film which is then further processed by either the tenter frame (see, for example, U.S. Patent No. 5,429,785) or double bubble method (see, for example, U.S. Patent No. 5,298,202).

As the film is produced it can be wound onto a windup roll for storage. The roll of film can be pre-folded in accordance with the type of package wrapping for which the film will be used and, if applicable, the type of machine used to wrap the film around the package(s). For instance, the film can be pre-folded as described and depicted in International PCT Publication No WO O1/64514₅ which is incorporated herein by reference. WO 01/64514 discloses at least two configurations that can be applied to the film of the present invention. In one configuration the film is used to form bags that may be used in five- face wrapping and in a second configuration the film is used to form tubes that may be used in four-face wrapping. In each case the configuration can be varied depending on the method by which the film is used to wrap a bundle (e.g. pallet) and the machine that is used to perform the wrapping.

In accordance with one embodiment of the present invention, the film is provided in a pre-folded film tube.

The film can be folded to form a U-film, where the opposed film panels formed by the fold are of equal size, or a J-film in which the opposed film panels are of different sizes. In the case of a U-film or a J-film, the closed edge of the film can alternatively be folded, for example by a gusset former, inwardly to form a gusset.

In accordance with another embodiment of the present invention, the film can be provided with microperforations, which allow condensation that has formed on the inner surface of the film to escape to the external environment. The microperforations also allow air to pass through the film, which promotes evaporation and escape of trapped moisture. The microperforations are provided as one or more bands that are continuous over the length of the film. The band is positioned on the film such that when an object is wrapped by the film, the microperforations are low on the sides, rather than on the top, of the wrapped bundle.

The microperforations are preferably made by puncturing the film with cold needles, but can alternatively be made by puncturing the film with hot needles. The average diameter of the microperforations should preferably be in the range of 5 to 50 microns. The density of the microperforations should preferably be in the range of 25-75 perforations per square inch, and most preferably should be 50 perforations per square inch- In a specific embodiment of the present invention, the microperforations of this embodiment are continuous over the length of the film in an approximately 3 inch wide band starting approximately 4 inches from the bottom edge of a U-folded film.

To gain a better understanding of the invention described herein, the following examples are set forth. It should be understood that these examples are for illustrative purposes only. Therefore, they should not limit the scope of this invention in any way. EXAMPLES

EXAMPLE 1: Clear 3-Iaver EIastomeric Film with Two Abrasion Resistant Layers

This Example provides a three layer abrasion resistant elastotneric film in which both the outer and inner layers are non-elastomeric and the middle layer is elastomeric. The components of the layers are as follows:

Layer A:

92% Total M3490 (metalϊocene based medium density polyethylene, density = 0.934, melt index = 0.9);

3% Antiblock (Spartech™ 2490) (anti-skid additive); - 2% Process aid; and

3% UV inhibitor (Chimasorb™ 944).

Layer B:

97% Nova FP-112 (mixed catalyzed LLDPE, density = 0,912, melt index= 0.8) or 100% Westlake Mxsten™ (advanced zeigler-natta catalyzed LLDPE, density = 0.905, MI = 0.6) or 100% Dow Attane™ 4201 (advanced ZN

LLDPE, density = 0.905, MI=LO) or Dow Affinity™ PLl 880 (metallocene catalyzed LLDPE, density = 0.902, melt index = 1.0) or 100% Dow Versify™ 3400 (metallocene catalyzed PP, density = 0.902, melt index = 1.0), or 100% 18% EVA such as Exxon Elvax™ or a combination thereof; and - 3% UV Inhibitor such as Chimasorb™ 944.

Layer C:

92% Westlake Hifor™ SC-7435OX (advanced zeigler-natta catalyzed LLDPE, density = 0.926, melt index = 0,6); 3% Antiblock Spartech™ 2490 (anti-skid additive); - 2% Process aid; and

3% UV inhibitor (Chimasoib™ 944).

Further examples of films having the above configuration and exhibiting abrasion resistance are described below: Example IA

A film as described above, except Layer A contains 1 % anti-skid agent, and the amount of resin is correspondingly reduced.

Example IB

A film as described above, except both Layers A and Layer C contain 1 % anti-skid agent, and the amount of resin in these layers is correspondingly reduced.

Example 1C

A film as described above, except Layer C contains 5% anti-fog agent, and the amount of resin is correspondingly reduced, Example ID

A film as described above, except Layer B contains 10% Calcium carbonate, and the amount of resin is correspondingly reduced.

Example IE

A film as described above, except Layer A contains 1% anti-skid agent, Layer C contains 10% calcium carbonate, and Layer B contains 5% anti-fog agent, with the amount of resin in these layers correspondingly reduced.

Example IF

A film as described above (including Examples 1 A-F)_f in which the film has a continuous approximately 3 inch wide band of microperforations starting approximately 4 inches from the bottom edge of a U-folded film. The microperforations have an average diameter of approximately 30 microns and a hole density of approximately 50 per square inch. EXAMPLE JZ; Opaqiiie 3-Layer Elastomerfc Vύm with Two Abrasion Resistant Layers

This Example provides a three layer, opaque, abrasion resistant elastomeric film in which both the outer and inner layers are non-elastomeric and the middle layer is elastomeric. The components of the layers are as follows:

Layer A:

- 87% Total M3490 (metallocene based medium density polyethylene, density = 0,934, melt index = 0,9);

3% Antiblock (Spartech™ 2490);

- 2% Process aid; - 5% White concentrate (70% loading of TiO₂); and

3 % UV inhibitor (Chimasorb™ 944).

Layer B:

87% Nova FP-112 (mixed catalyzed LLDPE, density = 0.912, melt index= 0.8) or 100% Westlake Mxsten™ (advanced zeigler-natta catalyzed LLDPE, density = 0.905, MI = 0.6) or 100% Dow Attane™ 4201 (advanced ZN

LLDPE, density = 0.905, MI=I .0) or Dow Affinity™ PLl 880 (metallocene catalyzed LLDPE₅ density = 0.902, melt index = 1,0) or 100% Dow Versify™ 3400 (metallocene catalyzed PP, density = 0.902, melt index = 1.0), or 100% 18% EVA such as Exxon Elvax™ or a combination thereof; - 3% UV inhibitor such as Chimasorb™ 944; and

10% White concentrate (70% loading of TiO₂).

Layer C:

87% Westlake Hifor™ SC-7435QX (advanced zeigler-natta catalyzed LLDPE, density ~ 0.926, melt index = 0.6); - 3% Antiblock Spartech™ 2490;

2% Process aid; 3% UV inhibitor (Chimasorb™ 944); and

- 5% Black concentrate (50% carbon black).

Further examples of films having the above configuration and exhibiting abrasion resistance are described below: Example 2 A

A film as described above, except Layer A contains 1 % anti-skid agent, with the amount of resin correspondingly reduced.

Example 2B A film as described above, except Layer A and Layer C contain 1 % anti-skid agent, with the amount of resin in these layers correspondingly reduced.

Example 2C

A film as described above, except Layer C contains 5% anti-fog agent, and the amount of resin is correspondingly reduced. Example 2D

A film as described above (including Examples 2A-D), where the film has a continuous approximately 3 inch wide band of microperforations starting approximately 4 inches from the bottom edge of a U-folded film. The microperforations have an average diameter of approximately 30 microns and a hole density of approximately 50 per square inch.

EXAMfLE 3: Two-Layer EIastomeric FUm with One Abrasion Resistant Lavfef

This Example provides a two-layer, abrasion resistant elastomeric film in which both the outer layer is non-elastomeric and the inner layer is elastomeric. The components of the layers are as follows: Layer A:

- 92% Total M3490 (metallocene based medium density polyethylene, density =

0.934, melt index = 0.9);

3% Antiblock Spartech™ 2490 (anti-skid additive);

2% Process aid; and - 3% UV inhibitor (Chimasorb™ 944). Layer C:

97% Nova FP-112 (mixed catalyzed LLDPE, density = 0.912, melt index= 0.8) or 100% Westlake Mxsten™ (advanced zeigler-natta catalyzed LLDPE, density = 0.905, Ml = 0.6) or 100% Dow Attane™ 4201 (advanced ZN LLDPE, density = 0.905, MI=LO) or Dow Affinity™ PLl 880 (metallocene catalyzed LLDPE, density = 0.902, melt index = 1.0) or 100% Dow Versify™ 3400 (metallocene catalyzed PP, density = 0.902, melt index = 1.0), or 100% 18% EVA such as Exxon Elvax™ or a combination thereof; and 3% TJV Inhibitor such as Chimasorb™ 944. Further examples of films having the above configuration and exhibiting abrasion resistance are described below:

Example 3 A

A film as described above, except Layer A contains 1% anti-skid agent, with the amount of resin correspondingly reduced.

Example 3B

A film as described above, except Layer A and Layer C contain 1% anti-skid agent, with the amount of resin in these layers correspondingly reduced.

Example 3C

A film as described above, except Layer C contains 5% anti-fog agent, and the amount of resin is correspondingly reduced.

Example 3D

A film as described above, except Layer A contains 1% anti-skid agent, Layer C contains 10% calcium carbonate and 5% anti-fog agent, and the amount of resin in Layer A and Layer C is correspondingly reduced.

Example 3E

A film as described above (including Examples 3 A-D), where the film has a continuous approximately 3 inch wide band of microperforations starting approximately 4 inches from the bottom edge of a U-folded film. The microperforations have an average diameter of approximately 30 microns and a hole density of approximately 50 per square inch.

The films described in this Example, including Examples 3A-E, are all clear films. By 5 changing the compositions such that Layer A contains 10% of a 70% white TiOj concentrate, and Layer C contains 5% of a 50% carbon black concentrate, with the amount of resin in Layer A and Layer C correspondingly reduced, opaque, two-layered abrasion resistant films are formed.

EXAMPLE 4: Three-laver Elastomeric Film with One Abrasion Resistant Layer

] 0 This Example provides a three-layer, abrasion resistant elastomeric film in which both the outer layer is non-elastomeric and the middle and inner layers are elastomeric. The components of the layers are as follows:

Layer A:

92% Total M3490 (metallocene based medium density polyethylene, density = 15 0.934, melt index = 0.9);

3% Antiblock Spartech™ 2490 (anti-skid additive);

- 2% Process aid; and

3% UV inhibitor (Chimasorb™ 944).

Layer C:

20 - 92% Nova FP-116 (mixed catalyzed LLDPE, density = 0.916, melt index =

0.8) or equivalent; 3% Antiblock Spartech™ 2490 (anti-skid additive);

- 2% Process aid; and

3% UV inhibitor (Chimasorb™ 944)

25 Layer B:

97% Nova FP-112 (mixed catalyzed LLDPE, density = 0.912, melt index= 0.8) or 100% Westlake Mxsten™ (advanced zeigler-natta catalyzed LLDPE, density = 0.905, MI = 0.6) or 100% Dow Attane™ 4201 (advanced ZN LLDPE, density = 0.905, Ml=LO) or Dow Affinity™ PL188O (metallocene catalyzed LLDPE, density = 0.902, melt index = 1.0) or 100% Dow Versify 3400 (metallocene catalyzed PP, density = 0.902, melt index = 1.0), or 100% 18% EVA such as Exxon Elvax™ or a combination thereof. 3% UV Inhibitor such as Chimasorb™ 944. Example 4 A

Example 4B

Example 4C

Example 4D A film as described above (including Examples 4A-D), where the film has a continuous approximately 3 inch wide band of microperftirations starting approximately 4 inches from the bottom edge of a U-folded film. The microperforations have an average diameter of approximately 30 microns and a hole density of approximately 50 per square inch. The films described in this Example, including Examples 4A-D₁ are all clear films. By changing the compositions such that Layer A contains 3.5% TiCb (active), Layer B contains 7% ΗO2 (active), and Layer C contains 2.5% carbon black (active), with the amount of resin in Layer A, Layer B, and Layer C correspondingly reduced opaque films having abrasion resistance are produced. EXAMPLE 5 - Demonstration of Abrasion Resistance in Elastomeric Films Having a Non-Elastomeric Outer Layer

This example is provided to illustrate the surprising result that if at least one of the polymer layers of a multi-layer film is made of an elastomeric material, and at least one layer is made of a non-elastomeric material, the resulting film has improved abrasion resistance in comparison to films comprised of entirely elastomeric layers. Films exhibiting such improved abrasion resistance are referred to as "abrasion resistant" and exhibit an elasticity only marginally less than that of films comprised entirely of elastomeric layers.

Film 1 and Film 2 set out below, are two non-limiting examples of 3-layer films that comprise two elastomeric layers and one non-elastomeric layer, according to two specific embodiments of the present invention. Films 1 and 2 were compared with a control film in which all of the layers are elastomeric.

Film l

C (15% of total film thickness): LLDPE (0.916 g/cm³)

B (70% of total film thickness): 70% POP (0.905 g/cm³) + 30% LLDPE (0.916 g/cm³) + 15% CaCO_? masterbatch

A (15% of total film thickness): LLDPE (0.926 g/cm³)

C (15% of total film thickness): LLDPE (0.916 g/cm³)

B (70% of total film thickness): 70% POP (0.905 g/cm³) + 30% LLDPE (0,916 g/cm³) + 15% CaCO₃ raasterbatch

A (15% of total film thickness): MDPE (0.934 g/ cm³) Control C (15% of total film thickness): LLDPE (0.916 g/cm³) B (70% of total film thickness): 30% POP (0.905 g/cm³) + 70% LLDPE (0.916 g/cm) + 15% CaCO₃ masterbatch A ( 15% of total film thickness) LLDPE (0.916 g/cm³) Layer C and Layer B of Film 1 and Film 2 are elastomeric, while Layer A is non- elastomeric. As stated above, all of the layers of the control film are elastomeric. The table below presents results of tests that were carried out on the three films described above.

The above tests demonstrate that Film 1 and Film 2 exhibit an overall gain in rigidity and retention force as compared to the control at a minimum cost of puncture and tear resistance decrease, and stretchability decrease.

In addition, field testing of films having the composition of Film 1 and Film 2 with an automatic packaging machine indicates that the films are satisfactorily stretchable and exhibit enhanced abrasion resistance in comparison to films consisting of only elastomeric layers.

EXAMPLE 6 - Effect of Anti-skid Additive on Abrasion Resistance

This Example demonstrates that incorporation of anti-skid additive in one or more layers of an elastomeric film improves the abrasion resistance of the film, in comparison to films that do not contain any anti-skid additive. Elastomeric films containing an anti-skid additive in the outer layer were prepared according to the teaching of Canadian Patent No. 2,474,143 (designated RWP 2004 and RWP 2005). The prepared films did not include a non-elastomeric layer.

The films were subsequently tested for abrasion resistance. First, a bundle was wrapped with the film to be tested and placed on a surface. The surfaces used in this study were wood (as used in pallets), rubber, gypsum and antislip material and were used in dry and in wet conditions. One end of the surface was then raised such that the surface was inclined from horizontal. The bundle was monitored for onset of motion down the inclined surface and the angle at which onset of motion was recorded.

The results of these studies are provided in Figures 1 and 2, which show that under both dry and wet conditions, a larger onset of morion angle was obtained on the wood, rubber and gypsum surfaces, using the anti-skid containing films in comparison to the elastomeric film that did not contain anti-skid. The larger angle at which onset of motion was observed was indicative of the anti-skid effect of the anti-skid additive.

The films were subsequently inspected for damage due to abrasion caused by slipping down the inclined surface. The films including the anti-skid additive exhibited abrasion resistance in that little or no damage due to abrasion was observed. This is in contrast to the damage observed in the elastomeric film that did not contain the anti-skid.

Further, the coefficients of friction (COFs) between various films and wood were determined using standard techniques. The elastomeric films containing an outer layer comprising an anti-skid additive (designated RWP 1, RWP 2, RWP 3 - clear and RWP 3 - B/W) were found to have a higher COF than the elastomeric film that did not contain the anti-skid additive. Nonetheless, these films also demonstrated an improved abrasion resistance in comparison to the elastomeric film that did not contain the anti-skid additive.

All publications, patents and patent applications mentioned in this Specification are indicative of the level of skill of those skilled in the art to which this invention pertains and are herein incorporated by reference to the same extent as if each individual publication, patent, or patent applications was specifically and individually indicated to be incorporated by reference.

The invention being thus described, it will be obvious that the same may be varied in many ways, Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An elastømeric film comprising:

(a) an outer layer that is non-elastomeric and provides increased abrasion resistance in said elastomeric film as compared to the abrasion resistance of an elastomeric film that does not include the non-elastomeric layer; and

(b) at least one elastomeric layer.

2. The elastomeric film according to claim 1 , which includes an inner nqn-elastomeric layer and a middle elastomeric layer.

3. The elastomeric film according to claim 1, which includes an inner elastomeric layer and a middle elastomeric layer.

4. The elastomeric film according to any one of claims 1 - 3, wherein each elastomeric layer comprises a resin or blend of resins having an overall density of 0.918 g/cm³ or less.

5. The elastomeric film according to any one of claims 1 - 4, wherein at least one layer of the film includes about 0.1% - about 20% by weight, based on the total weight of said at least one layer, of an anti-skid additive.

6. The elastomeric film according to claim 5, wherein the anti-skid containing layer comprises about 0.3% - about 10% by weight of the anti-skid additive.

7. The elastomeric film according to claim 5 or 6, wherein the anti-skid additive is present in the outer layer of the film.

S. The elastomeric film according to claim 5 or 6, wherein the anti-skid additive is present in the outer layer of the film and the inner layer of the film.

9. The elastomeric film according to any one of claims 1 - 8, wherein at least one layer of the fϋbm comprises one or more film additive, which film additive is a pigment, a slip agent, an anti-static agent, an anti-fog agent, an antioxidant, a heat stabilizer, a filler, a radiation stabilizer or an anti-blocking agent,

10. The elastomeric film according to any one of claims 1 - 9, wherein the noπ- elastømeric layer also provides improved heat resistance in said elastomeric film as compared to the heat resistance of said elastomeric film that does mot include the non- elastomeric layer.

IL A method of manufacturing an elastomeric film with improved abrasion resistance comprising: combining a non-elastomeric layer with at least one elastomeric layer such that the non-elastomeric layer becomes the outer layer of the elastomeric film, wherein the abrasion resistance of said elastomeric film is improved in comparison to an elastomeric film that does not include a non-elastomeric outer layer.

12. The method according to claim 11, wherein said elastomeric film is prepared using a blown film process.

13. The method according to claim 11 , wherein said elastomeric film is prepared using a cast film process.

14. The method according to claim 11, wherein said step of combining includes adhering the non-elastomeric layer to one of the at least one elastomeric layers.

15. A method of improving the abrasion resistance of an elastomeric film comprising: adding about 0.1% - about 20% by weight of an anti-skid additive to a mixture used to prepare a layer of said elastomeric film_} wherein said weight percent is based on the total weight of said mixture.

16. The method according to claim 15, wherein the anti-skid additive is added in an amount of about 0.3% - about 10% by weight.

17. The method according to claim 15 or 16, wherein the anti-skid additive is added to the mixture used to prepare the outer layer of said elastomeric film.

18. The method according to claim 15, which comprises the additional step of adding about 0.1% - about 20% by weight of the anti-skid additive to a second mixture used to prepare a second layer of said elastomeric film, wherein said weight percent is based on the total weight of said second mixture.

19. The method according to claim 18, wherein the anti-skid additive is added to said second mixture in an amount of about 0.3% - about 10% by weight.

20. The method according to claim 15 or 16, wherein the anti-skid additive is added to the mixture used to prepare the outer layer of said elastomeric film and to the second mixture, which is used to prepare the inner layer of said elastomeric film.

21. The method according to any one of claims 15 - 20, wherein the elastomeric film includes a non-elastomeric outer layer.

22. The method according to any one of claims 15 - 20, wherein the elastomeric film does not include a non-elastomeric layer.

23. Use of an anti-skid agent to improve the abrasion resistance of an elastomeric film.