WO2007095667A1

WO2007095667A1 - Improved product packaging

Info

Publication number: WO2007095667A1
Application number: PCT/AU2007/000128
Authority: WO
Inventors: Mladen Marco Smolcic; Pat Albert O'brien; Steward Geoffrey Gunn; Grant Thomas Harpur
Original assignee: Huhtamaki New Zealand Limited
Priority date: 2006-02-20
Filing date: 2007-02-12
Publication date: 2007-08-30
Also published as: AU2007219037A1; WO2007095667A8

Abstract

The present invention relates to a film (10), having advantageous puncture resistance. The film (10) includes at least one layer having relatively favourable puncture resistance (12); at least one barrier layer having favourable gas egress and ingress resistance (18); and at least one seal layer (30) having favourable sealing properties and a lower density relative to the at least one puncture resistant layer having favourable puncture resistance (12) wherein the at least one seal iayer (30) is at least of a similar thickness to the at least one puncture resistant layer having favourable puncture resistance (12).

Description

IMPROVED PRODUCT PACKAGING FIELD OF INVENTION

The present invention relates to the field of plastic films and packaging components. In one form, the invention relates to the packaging of meat and other food products and provides a method of manufacturing plastic films.

It will be convenient to hereinafter describe the invention in relation to meat packaging and the meat packing industry, however, it should be appreciated that the present invention is not to be seen as being limited to any one particular field of application. For example the invention may find application in the packaging of computer components and medical devices.

Furthermore in a film two layers are to be understood as, and are herein defined as, embracing a single layer performing the equivalent function of two similar layers. BACKGROUND ART

The discussion throughout this specification comes about due to the realisation of the inventors and/or the identification of certain prior art problems by the inventors. , ^'

Films for packaging are sometimes formed from polymeric material and are accordingly referred to as polymeric films. These films are often characterised in terms of their heat sealing and/or puncture resistance properties.

Both heat sealing and puncture resistance are particularly important properties when using packaging products for food products such as meat, poultry and cheese. With meat packaging in particular it is known that some conventional packaging arrangements currently used on the market do not sufficiently prevent the sharp edges of bones from puncturing the packaging. The problem is exacerbated by external abrasion between adjacent packages that occurs during transport as the products jostle and vibrate against one another.

Once a package is punctured the product is subject to subsequent damage and/or spoiling.

There is a continued need, at least in the meat packaging industry, for improved packaging and sealing products and methods. It would accordingly be advantageous if preferred arrangements of the invention could be provided for use in the packaging industry, in general, or at least provide the public with a useful choice. ■

Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms a part of the prior art base or the common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure, inclusive of the claims. SUMMARY OF INVENTION According to a first aspect of the invention there is provided a film comprising at least one puncture resistant layer having favourable puncture resistance; at least one barrier layer having favourable gas egress and ingress resistance; and at least one seal layer having favourable sealing properties and a lower density relative to the at least one puncture resistant layer wherein the at least one sea! layer is substantially thicker that the at least one puncture resistant layer having favourable puncture resistance.

The at least one puncture resistant layer may be selected from a group consisting of very low density PE (VLDPE), higher olefin copolymers of linear low density polyethylene (LLDPE) single-site catalysed linear low density polyethylenes (i.e. mLLDPE), ethylene vinyl acetate (EVA), ionomer, polyolefin plastomers (POP), or blends thereof and Nylon homopolymers or copolymers including Nylon 6, Nylon 6,6, Nylon 6/6,6, Nylon 4,6, Nylon 10, Nylon 12, amorphous Nylon. Most preferably the at least one puncture resistant layer is selected from the group consisting of very low density PE (VLDPE), higher olefin copolymers of linear low density polyethylene (LLDPE) single-site catalysed linear low density polyethylenes (i.e. mLLDPE), ethylene vinyl acetate (EVA), ionomer, polyolefin plastomers (POP).

Preferably the at least one seal layer is selected from a group consisting of very low density PE (VLDPE), copolymers of linear low density polyethylene (LLDPE) multiple- or single-site catalysed linear low density polyethylenes (i.e. mLLDPE), ethylene vinyl acetate (EVA), ionomer, polyolefin plastomers (POP), or blends thereof. The at least one barrier layer having favourable gas egress and ingress resistance may be selected from a group consisting of medium barrier materials consisting of Nylon homopolymers or copolymers including Nylon 6, Nylon 6,6, Nylon. 6/6,6, Nylon 4,6, Nylon 10, Nylon 12, and amorphous Nylon, and Nylon- clay nanocomposites and high barrier materiafs including polyvinylidene chloride (PVdC), polyvinyl alcoho! (PVOH) and ethylene vinyl alcohol copolymer (EVOH).

The film may include at least one tie layer. The at least one tie layer may be selected from a group consisting of ionomers, modified ethylene vinyl acetates, acid copolymers, grafted polyolefines, or blends thereof with compatible materials from the all above mentioned materials. Preferably the at least one tie layer is a nylon and polyethylene bonding layer.

According to a second aspect of the invention there is provided a film comprising: a barrier layer having favourable gas egress and ingress resistance two first layers respectively disposed on opposite sides of the barrier layer, each having favourable puncture resistance; and a low density polythene layer of a thickness substantially greater than at . least one of the first layers, the or each of the at least one of the two first layers being provided for the purpose of providing a relatively increased portion of puncture resistance reinforcement at regions of varying direction.

Preferably first layers each comprise a polyamide or nylon layer and the regions of varying direction comprise comers formed by the film. The low density polyethlyne layer may be disposed on the same side of the barrier layer as the polyamide layer relative to which the low density polyethelne layer has a substantially greater thickness. Preferably a first one of the poiyamide layers has a greater thickness than the other one of the polyamide layers and is disposed on the opposite side of the barrier layer, relative to the low density polyethylene layer.

The low density polythene layer may be of a thickness at least three times greater than the or each at least one of the two polyamide layers. The low density polythene fayer may be of a thickness at least four times greater than the or each at least one of the two polyamide layers. The low density polythene layer may be of a thickness at least five times greater than the or each at least one of the two polyamide layers. The low density polythene layer may be of a thickness at least 10 times greater than the or each at least one of the two polyamide layers.

Preferably a first one of the polyamide layers has a greater thickness than the other one of the polyamide layers. The first one of the polyamide layers may be at least three times thicker than the other one of the polyamide layers. The first one of the polyamide layers may be at least five times thicker than the other one of the polyamide layers. The first one of the polyamide layers may be at least ten times thicker than the other one of the polyamide layers. The film may be more than 150 gauge. The film may be more than 380 gauge. The film may be more than 520 gauge.

The applicant has provided a detailed description of several examples that are considered to fall within the scope of the present invention. Reference is to be made to /the examples in considering preferred gauge thicknesses, layer positions, and layer properties. Relative thicknesses and properties are also to be considered. Other aspects and preferred aspects are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention.

Furthermore the film may include active/intelligent/smart/responsive materials including antimicrobial materials, oxygen scavenging materials, moisture scavenging materials, and ethylene scavenging materials. The film may include any of a number of additives for product protection and appearance.

These include UV light protection, antifog, antistatic, antioxidants, freshness indicators, temperature indicators, slip and antiblock, cross linking, nucleating agents, and mould release. The film may also be coloured by any organic or inorganic colorants that are suitable for contact with food (in food related applications) and are added to a polymeric layer or an adhesive used for lamination of two films

Preferably the barrier material comprises EVOH. and the at least one polyethylene layer includes a copolymer of ethylene and octane. Advantageously the copolymers such as the preferred copolymer of ethylene and octane provides high puncture resistance and excellent seal properties. These seal properties include a low seal initiation temperature, a broad sealing window, and excellent sealing through contamination. It has been realised that the use in the film of the copolymer of ethylene and octane is advantageous

The polyamide may be provided as a blend or single resin. A blend of copolymer of PA6 and PA66, or Amorphous PA is particularly preferred due to its high chemical resistance, high impact strength, high toughness and heat resistance.

Preferably the at least one tie resin layer comprises a LLDPE based resin.

LLDPE has higher tensile strength and higher impact and puncture resistance than LDPE. It has better stress cracking properties than LDPE, is flexible and elongates under stress. LLDPE also has better environmental stress cracking resistance. The tie resin is used to bond incompatible polymeric materials.

Preferably the at least one EVOH layer comprises about 38 mol% ethylene content to ensure low oxygen permeability and good thermo-formability. Desirably, the EVOH layer is used as a core layer and is shielded on either side thereof by layers of polymeric material.

Preferably slip and anti-block additives are used in the film. When used for packing perishables, preferably each of the materials is approved for direct or indirect contact therewith.

Preferably the seal layer facilitates lock or controlled peel seal. In arrangements mono or multilayers of polymeric or composite material may be used. Polymeric material may be selected from the following group comprising; low density polyethylene; linear low density polyethylene copolymers made by using catalysts such as metallocene or others; high density polyethylene; polyolefin plastomer; ethylene vinyl acetate copolymers; ethylene acrylic acid copolymers; ionomers; polypropylenes; polyamide copolymers; amorphous polyamides; tie resins; oxygen barrier materials such as polyamides,

EVOH, PVdC and metallised coatings; and poiybutene-1. Other forms of polymeric and/or composite material may be used.

In preferred arrangements of the present invention there is advantageously provided a high performance packaging film that is able to replace, at least to some degree, expensive and complex packaging arrangements which traditionally combine two or more packaging materials. According to other aspects of the invention there are provided methods manufacturing and using packaging fiim.

As .would be apparent the film, in arrangements, provides an advantageous package for products that protects the products against damage and loss of their physical properties form both internal and external sources. The physical properties of the film preferably provide for high integrity that results in reduced product contamination, spoilage and loss.

Particularly preferred arrangements of the present invention may have the following packaging applications including packaging: meat with sharp protruding bones and other meat products; fish and seafood with sharp protruding bones or shells; dairy products; bakery products; fresh produce; vegetables; fruit; pet food; chemicals; industrial products; electronics; various forms of products that are typically, packed by vacuum skin packaging; medical devices; and liquid substances. As such, the present invention is expected to find application in a wide range of areas including those in which the packaging is required to protect against damage and loss of the physical properties of the packed product from both internal and external sources.

The particular multilayer film is able to provide a number of advantageous features including high puncture resistance on both the flat sheet and comer areas at folds of the film. Furthermore, arrangements have the ability to exhibit high tear and impact resistance on both the flat sheet and corner areas. The tensile strength is able to have advantageous yield • strength and elongation, advantageous ultimate break strength and elongation, and advantageous break energy. There is a high toughness while at the same time providing a barrier against oxygen ingress, and exhaust, carbon dioxide ingress and exhaust, nitrogen ingress and- exhaust, moisture ingress and exhaust and external taint

, factors.

In addition, particular forms have advantageous flavour retention, high oil resistance and retain freshness of the packed product. The film also performs very well when in the form of a pouch or tray.

The method may include deep draw forming and given that the advantageous properties of the film are sufficiently retained after the process there is provided an advantageous result. The method may include subjecting the film to sub zero conditions. The properties of the film are advantageous in that the film is able to largely retain its properties whilst subject to these conditions.

The method may include controlling the film orientation in the machine and transverse directions for low resistance to forming.

Other aspects and preferred aspects are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention wiil become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

Further disclosure, objects, advantages and aspects of the present application may be better understood by those skilled in the relevant art by reference to the following description of preferred embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and in which:

Figure 1 is a cross sectional illustration of a film according to a first preferred embodiment of the invention;

Figure 2 is a cross sectional illustration of a film according to a second preferred embodiment of the invention; Figure 3 is a cross sectional illustration showing relative proportions of the first and second preferred embodiments shown Figures 1 and 2;

Figure 4 is a cross sectional illustration of a thermoformed pack according to a third embodiment of the invention, the pack using the films of the first and second embodiments; Figure 5 is a side view illustrating a lamination process used in the manufacture of the second embodiment;

Figure 6 is a perspective view of the thermoformed pack shown in Figure 4; Figure 7 shows a plurality of preferred embodiments of the invention; Figure 8 is an illustration of a method of manufacture according to yet another embodiment of the invention;

Figure 9 is an illustration of a step in the method of manufacture illustrated in Figure 8 and

Figure 10 is a cross sectional illustration of a two embodiments of the invention forming a pack according to yet another preferred embodiment of the invention;

Figure 11 is a similar view to Figure 10 showing a further pack according to an embodiment of the invention; and

Figure 12 is a similar view to Figure 10 showing a cross sectional illustration of a yet a further pack according to an embodiment of the invention. DETAILED DESCRIPTION

Referring to Figure 1 there is shown a web 10 according to a first embodiment of the present invention. The web 10 includes seven primary layers and has superior puncture resistance properties in comparison to other arrangements.

In the web 10 the first four layers form a layer 12. The layer 12 comprises a nylon layer 14, a nylon layer 16, an EVOH layer 18 and a nylon layer 20. The nylon layer 20 is joined to a layer 24 by a tie layer 22. The layer 24 comprises a ^' first layer 26 a second layer 28

The layer 12 provides a barrier layer 12 that has a favourable resistance to gases including oxygen, nitrogen and carbon dioxide. The layer 24 provides a sealing layer 30 that has favourabfe sealing properties. Both the first layer 26 and the second layer 28are formed from LLDPE

The barrier layer 12 and the sealing layer 30 both provide advantageous puncture resistance properties.

The nyfon layers 14, 16, and 20 have favourable puncture resistance properties while the EVOH layer 18 has favourable resistance to the above mentioned and other gases. The nylon layer 14 provides a slip/antiblock function and is disposed on the top side of the web 10.

With this embodiment the nylon layers 14 and 16 each have a gauge of 20 and together provide for about 25% of the web 10. The resin used is Novamid 2030 [PA6.66 (Mitsubishi)]. The resin density is 1.13. The slip/antiblock used is CMB 7361 [EMS Grivory]. In each of the layers 14, 16 the slip antiblock forms 3% of the layer.

The EVOH layer 18 provides about 10% of the web 10 and has a layer gauge of 16. The resin used is Soarnol ET3803 [EVOH(Nippon Gohsei)] and the resin density is 1.17. As a result the layer has favourable resistance to oxygen ingress and exhaust, carbon dioxide ingress and exhaust, nitrogen ingress and exhaust, moisture ingress and exhaust and external taint. The layer 18 provides high flavour retention, high oil resistance, and retains the freshness of the packaged product.

The nylon layer 20 is formed form the same material as nylon layers 14, 16 with the same gauge of 20..

The tie layer 22 is disposed below the nylon layer 20 with a gauge of 16 with a resin density of 0.92. The resin used comprises Modic M533 [Grafted polyolefin (Mitsubishi Chem.)]

The layers 26, 28 in layer 24 form about 43% the web 10. The resin used comprises Elite 5220 [LLDPE (DOW Chemical)]. The layer gauge of the layers

26, 28 is about 88 and the resin density is 0.915. Resin 100157[Slip/antiblock

(Ampacet)] forms about 1 % of the layer and 10477 [Antiblock (Ampacet)] forms about 2% of the layer.

The form of the web 10 is summarized below for convenience.

A variation of the first embodiment is detailed below in tabular form.

In the variation the size of the EVOH layer 18 been increased by about

62%. Also if the nylon layer 14 had been increased by the same ratio the gauge of the nylon layer 14 would have been about 32. In the present case the gauge of the layer 14 has however only been about 25%. Reference is to be made to the relative proportions of each of the layers in the first and second variations.

Overall the variation has more LLDPE in outer layers, and consequently there is provided more puncture resistance and increased distance between what could be the bone of product and the EVOH layer 18. Referring to Figure 2 there is shown a web 32 according to a second embodiment of the invention. The web 32 can be viewed either from the top or from the bottom. The web 32 has similarities with the web 10 when viewed from the bottom. For ease of explanation the web 32 will be considered from the top.

Similarly to layer 24 of the web 10 the web 32 includes a first layer 34having favourable seal properties. The layer 34, hereinafter referred to as seal layer 34, comprises a first layer of LLDPE 36, a second layer of LLDPE 38 and a third layer of VLPDE 40. The first and second layers 36, 38 form a layer 42 of LLDPE similar to layer 24 in constituency. The layer 42 comprises Elite 5220 [LLDPE (DOW Chemical)] resin having a resin density of 0.915. Resin 100157[Slip/antiblock (Ampacet)] forms about 1% of the layer and resin 10477[Antiblock (Ampacet)] forms about 2% of the layer. The layer gauge is however 75 as opposed to 88. Layer 42 provides 50% of layer 34., The remaining 50% is provided by layer 40 formed from Attane 4404 [VLDPE (DOW Chemical)]. The resin density is 0.904. Again resin 100157[S!ip/antiblock (Ampacet)] forms about 1% of the layer and 10477[Antiblock {Ampacet)] forms about 2% of the layer.

The first layer 34 forms an upper web 44 that is adhesively bonded to a lower web 46. An adhesive layer 48 is used in the bonding process. Similarly to web 10 the lower web 46 includes a barrier layer 50 having favourable resistance to gases including oxygen, nitrogen and carbon dioxide. As with web 10 the barrier layer 50 comprises a layer 52 of EVOH formed from Soarnol ET3803 [EVOH(Nippon Gohsei)] resin having a resin density of 1.17. The resin gauge is however 33 and the layer provides 16.6% of the lower web 46.

Above layer 52 there is disposed a layer of nylon 54 comprising resin

Novamid 2030 [PA6, 66 Mitsubishi] having a gauge of 38 and a resin density of 1.13.. The layer provides about 8% of the lower web 46. A further layer of nylon

56 is disposed below the layer 52 the layer comprises resin Novamid 2030

[PA6,66 (Mitsubishi)] having a density of 1.13 and a layer gauge of 76.

Above the layer of nylon 54 there is disposed a layer of LLDPE 58 comprising Elite 5220 [LLDPE (DOW Chemical)]. The layer provides about 19 % of the lower web 46 and has a layer gauge of 47.5 with a resin density of 0.915. The layer is formed on top of the layer 54 with the use of a tie layer 60. In a similar fashion_. a tie layer 62 is used to fix a layer 64 to nylon layer 56. Again the tie layer 60 comprises Modic M533 [Grafted polyolefin (Mitsubishi Chem.)] having a resin density of 0.92. The tie layer 60 has a layer gauge of 10,5 The form of web 46 is summarized below for ready reference.

Thus is will be seen that the web 10 is accordingly provided in the form of nylon + slip/antiblock, nylon, EVOH, nylon, Tie, LLDPE, LLDPE + slip/antiblock. Nylon/nylon/EVOH/nylon are ail barrier layers while Nylon is also a puncture resistant layer. The LLDPE/LLDPE are seal and puncture resistant layers.

As shown in Figure 3, the EVOH barrier layer 18 will be spaced at least about 124 microns away from any sharp bones. The 104 microns comprises 88 gauge LLPDE from the seal layer 24, 6 gauge from the tie layer 22 and 20 gauge from the nylon layer 20. The nylon layer 20 and the seal layer 24 combine to space the EVOH layer 18 relatively far from the bones with favourable puncture resistance properties provided. In the embodiment the EVOH barrier layer 18 provides good gas transfer resistance whilst at the same time being protected by the exterior nylon layer 14 of 60 gauge. The nylon layer 14 and the nylon layer 20 accordingly protect EVOH barrier 18 between two tough and puncture resistant layers. This occurs even if the meat contact layers are damaged due to abrasion, or scratching. As a consequence, the barrier 18 will remain intact and provide for long shelf life. The thick puncture resistant layers will be the layers in contact with any sharp bones.

Similarly the web 32 is provided in the form of LLDPE + slip/antiblock,

LLDPE, VLDPE₁ Adhesive, LLDPE (Elite) / Tie(Modic) / Nylon (Novamid) / EVOH

/ Nylon (Novarnid) / Tie (Modic) / LLDPE(Efite). The layer depths and form in this embodiment are advantageous. Other advantageous layer depths and form are also described.

Figure 4 shows a thermoformed pack 66 comprising the web 10 as a top web 10 and the web 32 as a bottom web 32. In the thermoformed pack 66 the corners 68are the weakest and thinnest locations due to the manufacturing process. Returning now to Figure^' 3 it is clear that the seal layer 34 in combination with the layer of LLDPE 58 and the layer of nylon 54 protect the EVOH layer 52 in the bottom web 32. In the arrangement, the seal layer 34 in combination with the layer 58 is sufficiently thick to provide puncture resistance on its own, without support of the additional tough and puncture resistant Nylon layer. Nevertheless the presence of the nylon layers in the arrangement is advantageous in that the nylon layers provide additional relative toughness and puncture resistance in corners 68 of the deep drawn bottom web 32 in the pack 66.

Accordingly the nylon layers serve two primary functions. They provide additional toughness and puncture resistance in corners of deep drawn bottom web 32 and also provide protection for the EVOH layer 52.

The combination of the sea! layer 34 in the form of upper web 44 with the lower web 46 provides an improved and advantageous arrangement The combination of favourable puncture resistance provided by the upper web 44 with favourable barrier properties for shelf life and corner reinforcement from the lower web 46 is a distinct improvement over current systems. The webs 44 and 46 are combined to offer barrier and puncture resistance in a single film, With the first embodiment similar advantages appiy

The polyethylene resin of layer 26, layer 28, layer 36, layer 38, layer 58, and layer 64 is a linear low density ethylene-octane copolymer, manufactured by DOW Chemicals having an advantageous and specific combination of puncture resistance, stiffness, toughness and sealability characteristics. The layer 40 also has advantageous and specific characteristics with regard to puncture resistance, strength, stiffness, toughness, optical properties and sealability. The polymer is a very low density ethylene-octane copolymer, manufactured by DOW Chemicals. Preferred alternatives include: very low density metaliocene linear low density ethylene-alpha olefin copolymers from Mitsui Chemicals; and other single site catalysed linear low density ethyiene-alpha olefin copolymers from Dow Chemicals, Exxon Chemical and Nova Chemical.

The selection of Nylon is based upon parameters including high strength and toughness, high flex-crack resistance, high puncture resistance, barrier to gases, high resistance to oils and greases, and easy thermoformability. The Nylon layers in the web consist of single resin: Nylon copolymer 6,66 or a blend of Nylon copolymer 6,66 + amorphous Nylon. The preferred material is Nylon 6,66 copolymer Novamid from Mitsubishi Engineering Plastics. It offers balanced combination of properties for deep draw applications. Amorphous Nylon in the blend provides additional strength for deep draw applications and is particularly advantageous at the corners of the pack 66. Alternative Nylons can be chosen from the group consisting of Nylon homopolymers or copolymers {i.e. Nylon 6, Nylon 6,6, Nylon 6/6,6, Nylon 4,6, Nylon 10, Nylon 12, amorphous Nylon), Nylon- clay nanocomposites from Mitsubishi -Engineering Plastics, DSM Engineering Plastics and Bayer Plastics. In the embodiment the EVOH barriers 18 and 52 are of a type from Nippon

Gσhsei having 38 mo!% ethylene content EVOH. Generally the barriers 18 and 52 will be selected from the group consisting of medium barrier materials such as Nylon homopolymers or copolymers (i.e. Nylon 6, Nylon 6,6, Nylon 6/6,6, Nylon 4,6, Nylon 10, Nylon 12, amorphous Nylon), Nylon-clay nanocomposites and high barrier materials such as polyvinylidene chloride (PVdC), polyvinyl alcohol (PVOH) and ethylene vinyl alcohol copolymer. Preferred alternatives would be other grades of EVOH from Nippon Ghosei arid EVOH grades from Eval Company.

The Ampacet slip additives are used to reduce each web's resistance to sliding over itself or parts of converting and packaging equipment. Antibiock additives are used to prevent blocking of two adjacent layers of film.

The tie layers are selected for an advantageous bond. The tie layers are provided for the bonding of incompatible polymers, Le. Nylon and polyethylene and will typically be selected from a group consisting of ionomers, modified ethylene vinyl acetates, acid copolymers, grafted polyolefines, or blends thereof with compatible materials from all above mentioned materials.

Most importantly each of the food contact materials used must be approved for direct contact with food in the relevant jurisdictions.

A notable advantage of the embodiment is that paper sack/polymeric film packaging may be replaced in applications requiring high puncture resistance and a high barrier. One example would be the bulk packaging of milk powder.

In this embodiment the top web 10 is manufactured as a single multilayer film. This can be achieved using standard film coextrusion equipment. The bottom web 32 is manufactured as a laminate of two single multilayer films. The process involves adhering the upper web 44 to the lower web 46 with the adhesive 48. Referring to Figure 5 it is shown that the upper web 44 is laminated from the roll on the left with the lower web 46 at lamination point 69. In the embodiment a solvent based lamination process is used. In other embodiments a water based lamination process or a polymeric based lamination process may be used instead.

Various forms of manufacture fall within the scope of the present invention.

At least cast film monolayer extrusion, cast film multilayer co-extrusion, blow film monolayer extrusion, blow film multilayer co-extrusion, multilayer extrusion coating, monolayer extrusion coating, multilayer extrusion lamination, and monolayer extrusion lamination methods are not to be excluded. The Huhtamaki cast film monolayer process is the preferred process as it yields better puncture resistance in comparison to other processes when resins of similar characteristics are used. This improvement is thought to be the result of lower crystallinity of the cast film due to inherently faster cooling of the film in comparison to other processes.

The thermoformed pack 66 is shown in Figure 6. The thermoformed bottom portion 70 of the pack 66 is formed by a deep draw forming method. The bottom web or film 32 provides for an advantageous puncture resistance both as a fiat sheet and in the form of the deep draw formed pack 66. As a flat sheet the film 32 is able to achieve at least 11 J total puncture energy at maximum puncture force..

When thermoformed into a thermoformed pack having a corner thickness of not less than 65um the film 32 exhibits a puncture resistance of at least 2 J total puncture energy at maximum puncture force. The tear resistance is also beneficial in that as a flat sheet the tear resistance is at least 25 N in machine direction and 25 N in transverse direction. Although high the impact resistance, is at yet not determined, as it is difficult to measure with standard testing equipment designed for impact forces less than 1 kg. The yield load is however at least 180 N/25mm in machine direction and the max load is at least 380 N/25mm in machine direction. The tensile strength is at least 40 MPa in machine direction, and further, the break elongation is at least 520% in machine. The break energy is at least 60 J in machine direction.

As an oxygen transmission barrier in flat sheet form the film 32 provides a transmission barrier of at least 0.5 cm³ /m² -24hrs-atm. As a pack 66, the film 32 provides a transmission barrier of at least 2 cm³ /m² -24hrs-atm at the corner of the thermoformed pack in which the thinnest section is not fess than 65um.

As a moisture transmission barrier the film 32, as a flat sheet, provides a barrier of at least 2 g/m² ~24hrs-atm. At the corner of the thermoformed pack previously described, in which the thinnest section is not less than 65um - of the pack, the film 57 acts as a moisture transmission barrier providing a barrier of at least 8 g /m² -24hrs-atm.

Turning to Figure 7 the film 32 is reverse printed and formed into a number of final products 72. These include a flat sheet 74, a pouch 76 and a tray 78. As would be apparent the final products 72 can be formed by any one of drape forming with a male mould, drape forming with a female mould, pressure forming, free forming, matched-mould forming, trapped-sheet pressure forming, and so on. The present invention is not to be seen as being limited to any one of these forming methods.

Advantageously the film 32 is suitable for deep draw forming in that afterwards the physical protective properties of the film 32 are sufficiently retained for working purposes. Furthermore, the film 32 sufficiently retains its physical properties in subzero conditions. In arrangements it is preferred that the tray 78 has the additional step of being either plug assisted vacuum formed, plug assisted pressure formed, slip . ring formed, vacuum snap-back formed, billow snap back formed and so on. The final product 72 and may be provided as a fiim for vertical form fill seal applications or as a film for horizontal form fill seal applications, pouch 76 or The top web 10 is preferably used as a lidding film 80 for the bottom portion 70 or is used as pouch 76. Both the lidding film 80 and the bottom portion 70 have advantageous characteristics of strength, toughness, puncture resistance and high barrier properties as respectively provided by the first and second embodiments. Furthermore, the fiim orientation in the machine and transverse direction have advantageous properties in that that the film 32 has a low resistance to forming. This occurs along with uniformity of wall thickness without excessive thinning as may otherwise be the case with conventional materials with a pouch or tray. In addition there are improved flex-crack resistance and fatigue properties along with high rigidity. Additionally, the excellent film flatness and surface properties allow for excellent processing of the package when in a packing line.

It will be apparent that the embodiments provides a high barrier and high puncture resistant multilayer polymeric packaging films suitable for applications that require ultra high protection for packaged products against damage and loss of physical properties from both internal and external sources. The films provide an excellent combination of strength, toughness, puncture resistance and barrier properties. Additionally embodiments may provide a substitute for traditional packaging materials that combine two or more packaging elements such as paper sack with inner polymeric films.

A method of manufacturing the tray 78 is show in Figure 8. At block A 1. the bottom web 32 is thermoformed into the bottom 70 of pack 66. At block B the product is put in the pack 66, At block C the top web 10 is sealed on the bottom web 32. At block D the pack is cut ready for freezing. As previously noted the tray 78 sufficiently retains its properties for working purposes when frozen.

The difference between the tray and bottom web is in terminology ... Both top web 10 and bottom web 32 are supplied in the reel form and are unwound on the packing line. Multiple trays in a single row can be formed and cutting is performed to form individual packs. After cutting the edges are trimmed to provide the finished pack. The trays are to be seen as being in existence when preformed in a row or when cut into individual products.

Figure 9 shows a block 86 used with four sources 82. The width 84 of the film is also illustrated. The Figure shows block with three colours representing three materials. In any respect, the block in the present embodiment takes four materials. In the block four materials are coded W X₁ Y and Z. They flow through the block in different combinations to give 7 layers of the finished (film. In the case of top web 10 four materials are contained in four extruders. The first extruder is a nylon extruder. The second extruder is a LLDPE extruder. The third extruder is a tie extruder and the fourth . extruder is an EVOH extruder. Configuration of channels in the block is WWZWYXX so W flows through 3 channels, Y through 1, Z through 1 and X through 2. The final result is accordingly Nylon/Nyion/EVOH/Nylonπϊe/LLDPE/LLDPE Another example is the seven layer bottom web 32. The extruders are respectively nylon, LLDPE, Tie, and EVOH. Configuration of channels in the block is XYWZWYX so W flows through 2 channels, Y through 2, Z through 1 and X through 2. The final result is accordingly LLDPE / Tie / Nylon / EVOH / Nylon / Tie / LLDPE. Other combinations can be achieved such as. XXYZYWW. The seal layer 24 has three layers. A similar system is used but the block has three channels and two materials W and X. In this particular case the configuration of the block is XXW. The first extruder, is vLLDPE and the second extruder is LLDPE. Figure 9 shows the width 84 of the web. Each of the materials meets at one point and flow together through the bottom of the block. Following this they spread in the wide die to form thin wide film.

In a further embodiment employing the variation of the top web 10 each of the webs 10, 44, 46 comprise the following structure. Top Web (10)

Bottom Web (46)

In another embodiment the top web is 280um, the bottom web 1 is 280um and bottom web 2 is 280um. Furthermore the layer proportions are changed to give longer shelf life as required. There is more EVOH and LLDPE is replaced with very iow density mLLDPE.

Top Web (10)

Bottom Web (46)

In another embodiment the gauge of the top web 10 is 180um, the gauge of the bottom web 44 is 200um; and the bottom web 46 is replaced with the top web 180um, with more EVOH, to avoid loss of barrier properties in the comers, and present a nylon layer on the outside. As a result, the bottom web 32 is now a laminate of bottom web 34 and top web 10. As a consequence all the outer surfaces comprise nyions when provided in the form of a pack and sealed This is advantageous because there is provided high resistance to chemicals, oils, and greases and not only with respect to the surface of the top web. ^' The structure looking from the top of the top web comprises: NYLON/NYLON/EVOH/NYLONATie/LLDPE/LLDPE/PRODUCTCMEATVLLDPE/LL DPEA/LLDPE/Adhesive/LLDPE/LLDPE/Tie/NYLON/EVOH/NYLON/NYLON. This embodiment is particularly advantageous for particular conditions. In a similar structure to before there is provided: Top Web (10)

Top Web

In other preferred embodiments of the invention there are provided advantageous oxygen scavenging and antimicrobial layers. In one variations there an mLLDPE Evolue SP1540 and oxygen scavenging material is added to the lower web 46 and a mLLDPE layer is added to the top web 10. Based on actual layers variation comprises:

Top Web (10)

In another alternative, materials in the seal layers 30 of the top web 10 are changed to mLLDPE Evolue SP0540 and an antimicrobial additive is added to seal layers. The structure comprises:

Top Web (10)

Bottom Web (46)

In yet another embodiment nanocomposite nylon having improved barrier properties in comparison to standard nylons is used as a replacement to provide opportunity to optimize barrier performance and eliminate unnecessary ("over engineered" and expensive) high barrier EVOH. Barrier properties will be lower

(than with EVOH) but this is acceptable if the required shelf life is shortened. This may be advantageous for the domestic market. In general if EVOH is replaced with standard nylon (Novamid 2030) sufficient barrier might be achieved for shorter shelf life applications. The embodiment comprises the follow actual structure:

Top Web

Bottom Web 2

Thus it will be seen that film (10) has advantageous puncture resistance and includes at least one layer having relatively favourable puncture resistance (12), at feast one barrier layer having favourable gas egress resistance (18), and at least one seal layer (30) having favourable sealing properties and a lower density relative to the at least one puncture resistant layer having favourable puncture resistance (12) wherein the at least one seal layer (30) is at least of a similar thickness to the at feast one puncture resistant layer having favourable puncture resistance (12). While this invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification(s). This application is intended to cover any variations uses or adaptations of the invention following in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth.

As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention as defined in the appended claims. Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention and appended claims. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be. practiced. In the following claims, means-plus-function clauses are intended to cover structures as performing the defined function and not only structural equivalents, but also equivalent structures. For example, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface to secure wooden parts together, in the environment of fastening wooden parts, a nail and a ^' screw are equivalent structures.

"Comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof." Thus, unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to";

Table of Numerals web 10 corners 68 layer 12 lamination point 69 barrier layer 12 bottom portion 70 nyion layer 14 final products 72 nylon layer 16 flat sheet 74

EVOH layer 18 pouch 76 nylon layer.20 tray 78 tie layer 22 lidding film 80 layer 24 four sources 821 first layer 26 width 84 second layer 28 .block 86 sealing layer 30 bottom web 32 sea! layer 34 first layer of LLDPE 36 second layer of LLDPE 38 third layer of VLPDE 40 layer 42 upper web 44 lower web 46 adhesive layer 48 barrier layer 50 layer 52 nylon 54 nyion 56 layer of LLDPE 58 tie layer 60 tie layer 62 layer 66 thermoformed pack 66

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A film comprising: at least one puncture resistant layer having favourable puncture resistance; at least one barrier layer having favourable gas egress and ingress resistance; and at least one seal layer having favourable sealing properties and a lower density relative to the at least one puncture resistant layer wherein the at least one seal layer is at least of a similar thickness to the at least one puncture resistant layer.

2. A film as claimed in claim 1 wherein the at least one seal layer is substantially thicker than the at least one puncture resistant layer.

3. A film as claimed in claim 1 or 2 wherein the at least one seal layer comprises two linear low density polyethylene layers.

4. A film as claimed in any one of claims 1 to 3 wherein the at least one barrier layer comprises an EVOH layer and two nylon layers, the EVOH layer being disposed between the two nylon layers.

5. A film as claimed in claim 4 wherein a thicker one of the two nylon layers, thicker relative to the other one of the two nylon layers, comprises a first and a second nylon layer.

6. A film as claimed in any one of claims 1 to 5 wherein the at least one barrier layer is disposed within the at least one puncture resistant layer.

7. A film as claimed in claim 6 wherein the thicker one of the two nylon layers has a free surface not adjoining any layer of the film, the thicker one of the two nylon layers thereby constituting an surface layer.

8. A film as claimed in any one of claims 1 to 7 wherein the at least one seal layer is arranged to space the at least barrier layer from sharp objects.

9. A film as claimed in claim 8 wherein the at least one seal layer comprises at ieast two layers of linear low density polyethylene arranged to space the at least one barrier layer away from sharp objects.

10. A film as claimed in claim 9 wherein the at least one seal layer comprises a first layer of LLDPE and a second layer of VLLDPE.

11. A provided a film comprising: a barrier layer having favourable gas egress and ingress resistance two first layers respectively disposed on opposite sides of the barrier layer, each having favourable puncture resistance; and a linear low density polythene layer of a thickness substantially greater than at least one of the first layers, the or each of the at least one of the two first layers being provided for the purpose of providing effective puncture resistance reinforcement at regions of varying direction,

12. A film as claimed in claim 11 wherein the first layers each comprise a nylon layer and the regions of varying direction comprise corners formed by the film

13. A film as claimed in claim 11 or 12, wherein the linear low density polyethylene layer is disposed on the same side of the barrier layer as the polyamide layer relative to which the linear low density polyethylene layer has a substantially greater thickness than the at least one of the first layers.

14. A film comprising: at least one puncture resistant layer having favourable puncture resistance; at least one barrier layer having favourable gas egress resistance; and at least one seal layer of at least of a similar thickness to the at least one puncture resistant layer having favourable puncture resistance.

15. A film as claimed in claim 14 including at least one element of the group comprising antimicrobial materials, oxygen scavenging materials, moisture scavenging materials, and ethylene scavenging materials.

16. A film as claimed in claim 14 or 15 having at least one of the group of properties comprising UV light protection, antifog, antistatic, antioxidants, freshness indicators, temperature indicators, slip and antiblock, cross linking, nucleating agents, and mould release.

17. A film substantially as herein described with reference to the accompanying drawings

18. A pack substantially as herein described with reference to the accompanying drawings.