Multi-layer barrier film

Abstract

The film comprises, in order, acrylic layer 12, first polyester layer 14, first barrier layer 16, polyolefin layer 18, second barrier layer 20 and second polyester layer 22. The barrier layers have lo

Description

Field This invention relates to a multi-layer barrier film for PSA packaging. Background Barrier films for packaging gas or moisture sensitive items such as food or medical devices have specific barrier properties with designated gas and moisture transmission rates, which helps to extend item shelf-life. It is known to package such items using barrier films coupled by pressure-sensitive adhesive (PSA). In one example, a first barrier film has an item receiving zone surrounded by a region of first PSA. Once an item has been placed on the item receiving zone, a second barrier film is applied to the first barrier firm with the item between them. The second barrier film is provided with a corresponding region of second PSA that adheres to the first PSA to enclose the item between the barrier films. The present inventors have devised a new type of barrier film that can enable PSA packaging of gas or moisture sensitive items at high line speeds and / or with improved barrier properties. Summary In accordance with a first aspect of the present invention, there is provided a multilayer barrier film comprising: a first Polyester layer; a second Polyester layer; a Polyolefin layer between the first and second Polyester layers; a first barrier layer between the first Polyester layer and the Polyolefin layer; a second barrier layer between the second Polyester layer and the Polyolefin layer; and a first acrylic layer on an opposite side of the first Polyester layer with respect to the Polyolefin layer, 16 1224 wherein each barrier layer has a gas and / or moisture transmission rate which is less than the gas and / or moisture transmission rate of the Polyester and / or Polyolefin layers. The film of the present invention may be suitable for use in packaging using a pressure sensitive adhesive (PSA). The present inventors have found that the presence of the acrylic layer can lead to PSA packaging having improved gas and / or moisture transmission rate i.e. improved barrier properties in comparison to known PSA packaging because the acrylic layer, which can be considered to be a primer layer, enables a lower coat weight of PSA to be used to join the film to a corresponding film, thereby decreasing the thickness of a PSA adhesive region joining the films. The inventors have also found that the acrylic layer can result in more consistent peel performance, where the PSA remains on only one of the two films when the packaging is opened to access an item within the packaging. A film according to embodiments of the invention can for example enable 50% or less PSA to be used while maintaining or improving adhesive performance and while improving barrier and peel characteristics. The multi-layer barrier film can further comprise a third Polyester layer and a third barrier layer between a first one of the first and second Polyester layers and the Polyolefin layer. The multi-layer barrier film can further comprise a fourth Polyester layer and a fourth barrier layer between a second one of the first and second Polyester layers, distinct from the first one, and the Polyolefin layer. The multi-layer barrier film can further comprise a second acrylic layer on an opposite side of the second Polyester layer with respect to the Polyolefin layer. The second acrylic layer can comprise a coating applied to a surface of the second Polyester layer. The first acrylic layer comprises a coating applied to a surface of the first Polyester layer. Each barrier layer can comprise a coating applied to respective surface one of the Polyester layers or the Polyolefin layer. 16 1224 The multi-layer barrier film can be arranged such that the first barrier layer is applied to a surface of the first Polyester layer between the first Polyester layer and the third Polyester layer to form a first web, the third barrier layer is applied to the third Polyester layer, optionally between the first Polyester layer and the third Polyester layer, to form a second web, the second barrier layer is applied to the second Polyester layer, optionally between the second Polyester layer and the forth Polyester layer, to form a third web and the fourth barrier layer is applied to the fourth Polyester layer, optionally between the second Polyester layer and the forth Polyester layer, to form a fourth web. The multi-layer barrier film can further comprise a fifth barrier layer applied to the third Polyester layer, optionally between the third Polyester layer and the Polyolefin layer, forming part of the second web. The multi-layer barrier film can further comprise a sixth barrier layer applied to the fourth Polyester layer, optionally between the fourth Polyester layer and the Polyolefin layer, forming part of the fourth web. The multi-layer barrier film can further comprise a seventh barrier layer, optionally applied to the Polyolefin layer between the Polyolefin layer and the third Polyester layer, or the fourth Polyester layer, to form a fifth web. Each web can be joined to one or both adjacent webs by adhesive. One or more, or each, barrier layer can comprise metal such as, but not limited to Aluminium (Al). One or more, or each, barrier layer can comprise a barrier coating. The barrier coating can comprise a metal or a non-metal or combinations thereof. The barrier coatings could consist of materials such as, but not limited to: Polyvinyl Alcohol (PVOH), Polyvinylidene dichloride (PVDC), Aluminium (Al), Aluminium Oxide (AIOx), Silicon Oxide (SiOx), Silicon Nitride (SixNx) or Indium Tin Oxide (ITO). One or more, or each of the barrier layers can be applied by a metallisation technique known within the field. This includes but is not limited to techniques such as: Chemical Vapour Deposition (CVD), Plasma Enhanced Chemical Vapour Deposition (PECVD), Physical Vapour Deposition (PVD), Thermal evaporation, Sputter coating or Atomic Layer Deposition. 16 1224 One or more, or each of the barrier coatings may be applied by other coating techniques. These could include but are not limited to techniques such as: Roll coating, Gravure coating, Spray coating or Dip Coating. One or more, or each, barrier layer can comprise a metallised coating applied to a layer of cured acylate applied to the respective Polyester or Polyolefin layer. The, or each, Polyester layer can comprise Polyethylene Terephthalate (PET) and / or the Polyolefin layer can comprise Polypropylene such as Orientated Polypropylene (OPP). This can lead to PSA packaging having improved gas and / or moisture transmission rate i.e. improved barrier properties. Brief Description of the Drawings By way of example only, certain embodiments of the invention will now be described by reference to the accompanying drawings, in which: Fig. la is a diagram illustrating layers of a multi-layer barrier film according to an embodiment of the invention; Fig. lb is a diagram illustrating the assembled a multi-layer barrier film of Fig. la; Fig. 2a is a diagram illustrating assembly of PSA packaging using films according to an embodiment of the invention; Fig. 2b is a diagram illustrating the assembled PSA packaging of Fig. 2a; and Fig. 3 is a diagram illustrating layers of a multi-layer barrier film according to another embodiment of the invention. Detailed Description Fig. la shows a multi-layer barrier film according to an embodiment of the invention is shown generally at 10. The barrier film 10 is configured to be used in pressuresensitive adhesive (PSA) packing. 16 1224 The film 10 is formed from a first polyethylene terephthalate (PET) layer 14, a second PET layer 22, an oriented polypropylene (OPP) layer 18 between the first and second PET layers 14, 22, a first barrier layer 16 between the first PET layer 14 and the OPP layer 18, a second barrier layer 20 between the second PET layer 22 and the OPP layer 18 and a first acrylic layer 12 on an opposite side 14a of the first PET layer 14 with respect to the OPP layer 18. The film 10 is shown in constructed form in Fig. lb. The OPP can be monoaxial or biaxial (stretched in a transverse or longitudinal direction, or in both). Each barrier layer 16, 20 has a gas and / or moisture transmission rate which is less than the gas and / or moisture transmission rate of the PET and / or OPP layers 14, 18, 22. The barrier layers 16, 20 can be formed from metal such as Aluminium (Al) or can be formed from Aluminium Oxide (AIOx), Silicone Oxide (SiOx) or Silicon Nitride (SixNx) for example. It is preferred that the barrier layers 16, 20 are coatings that are each applied to one of the PET and / or OPP layers 14, 18, 22. This can result in each barrier layer 16, 20 having a respective thickness T3, T5 typically between about 2 and about 100 nm and more preferably between about 5 and about 50 nm. The barrier layers can be applied using a process such as those described in EP2951850B1 or EP2168691B1. Likewise, it is preferred that the first acrylic layer 12 is a coating applied to an outer major surface (e.g., 14a) of one or both of the PET layers 14, 22. The first acrylic layer 12 can for example have a thickness T1 of about 10-3000 nm, preferably about 20-2000 nm and more preferably about 20-1000 nm. The PET layers 14, 22 can each have a respective thickness T2, T6 of about 5 pm to about 100 pm, preferably about 6-50 pm more preferably about 9-25 pm. In one specific example the thickness can be about 12 pm. The OPP layer 18 can have a thickness T4 of about 5-100 pm, preferably about 6-50 pm and more preferably about 9-40 pm. In one specific example the thickness can be about 12.5 pm. 16 1224 Thus, the total thickness TF of the film 10 can be about 20-300 pm, preferably about 30-200 pm and more preferably about 40-100 pm. In one specific example the thickness can be about 72 pm. In the illustrated embodiment, the first barrier layer 16 is a coating applied to the inward facing major surface 14b of first PET layer 14, the second barrier layer 20 is a coating applied to the inward facing major surface 22a of second PET layer 22 and the first acrylic layer 12 is a coating applied to the outer major surface 14a of the first PET layer 14. Thus, the six-layer film 10 can be formed from three webs W1-W3, the first web W1 being formed the acrylic layer 12, first PET layer 14 and the first barrier layer 16, the second web W2 being formed from the OPP layer and the third web W3 being formed from the second barrier layer 20 and the second PET layer 22. In order to construct the barrier film 10, the three webs W1-W3 can be laminated together; in one example, the webs W1-W3 can be joined by adhesive. It is preferred that a low gas adhesive is used to reduce the likelihood of gas bubbles forming in the film, which could affect the gas and / or moisture transmission rate of the film 10. In one example, the adhesive can be a two-part aliphatic isocyanate based polyester adhesive, although any suitable adhesive can be used. Due to the configuration of the layers, the film 10 is flexible and capable of being used in a high-speed packaging process. In some examples, the film can be moved at lines speeds of about 5 - 1000 m / min. Due to the configuration of the layers, the film 10 can have gas and / or moisture transmission rate no greater than about 0.05 g / m2 / day (tested at 38°C, 90% relative humidity (rh)). This can be particularly advantageous when the film 10 is used for packaging of oxygen or moisture sensitive materials, including medical devices such as test kit components for example. In one specific example, the film 10 can have gas and / or moisture transmission rate no greater than about 0.02 g / m2 / day (tested at 38 °C, 90% rh). Example barrier coatings can be, but are not limited to: • Aluminium (Al) = <1 cc / m2 / day OTR and <1 g / m2 / day MVTR • An Oxide of Aluminium (AIOx) = <5 cc / m2 / day OTR and <5 g / m2 / day MVTR 16 1224 • A hybrid coating of Acrylate and Aluminium and / or Aluminium Oxide applied as described in EP2168691B1 = <0.2 cc / m2 / day OTR and <0.2 g / m2 / day MVTR Above values all for the coating on a 12u PET. For comparison, typical values for uncoated 12u PET are 130-150 cc / m2 / day OTR and 30-50 g / m2 / day MVTR. ASTM Test methods can for example be: . OTR - D3985 • MVTR - F1240 During testing, rh can be controlled by commonly available machines that are known to the skilled person. Any suitable test method can be used; for example, for moisture vapor transmission rate (MVTR) testing, a Mocon Permatran can be used which tests according to ASTM F1249. Referring additionally to Figs. 2a and 2b, as noted above, the barrier film 10 is configured to be used in PSA packaging. In one example, a first barrier film 10a has an item receiving zone IZ surrounded by a region RI of first PSA. Once an item I has been placed on the item receiving zone IZ, a second barrier film 10b is applied to the first barrier firm 10a with the item I between them. The second barrier film 10b is provided with a corresponding item receiving zone IZ and corresponding region R2 of second PSA that adheres to the first PSA to enclose the item I between the barrier films 10a, 10b, as illustrated in Fig. 2b. The films 10a, 10b are each according to embodiments of the invention, such as the film 10 of Figs.la and lb. The films 10a, 10b are arranged to have the PSA regions RI, R2 applied to the acrylic coating layer 12 of the barrier film. The present inventors have found that the presence of the acrylic layer 12 can lead to PSA packaging having improved gas and / or moisture transmission rate in comparison to known PSA packaging because it enables a lower coat weight of PSA to be used to join the films 10a, 10b, thereby decreasing the adhesive region thickness TA illustrated in Fig. 2b. The inventors have also found that the acrylic layer 12 can result in more consistent peel performance, where the PSA remains on only one of the two films 10a, 10b when the packaging is opened to access the item I. 16 1224 Referring now to Fig. 3, a multi-layer barrier film according to a further embodiment of the invention is shown generally at 50. The film 50 is similar to the film 10 of Figs, la and lb and for brevity the following description will focus on the differences. The film 50 of this embodiment is made up of five webs W1A-W5A arranged to be laminated to one another by adhesive. The first web W1A is formed of a first PET layer 54 with a barrier layer 56 on a lower face and an acrylic layer 52 on an upper face. The second web W2A is formed of a second PET layer 60 with a barrier layer 58 on an upper face and a barrier layer 62 on a lower face. The third web W3A is formed of an OPP layer 66 with a barrier layer 64 on an upper face, or alternatively on a lower face or on both faces. The fourth web W4A is formed of a third PET layer 70 with a barrier layer 68 on an upper face and a barrier layer 72 on a lower face. The fifth web W5A is formed of a fourth PET layer 76 with a barrier layer 74 on an upper face and an acrylic layer 78 on a lower face. The present inventors have found that the fourteen-layer film of this embodiment has barrier properties which are suitable for applications such as PSA packaging of medical test strips and the like, which can be particularly sensitive to gas and moisture ingress through the packaging. Moreover, both upper and lower faces of the film 50 are provided with acrylic layers 52, 78, making the film suitable for application of PSA on either or both sides. In this embodiment, each barrier layer is a metallised aluminium layer, with layers 62 and 68 being applied using a process as described in EP2951850B1 or EP2168691B1, whereby a radiation curable material such as acrylate is condensed on the PET surface and then metallised. In other embodiments each barrier layers can be formed in this manner and in other embodiments none can be formed in this manner. While two specific films 10, 50 have been described, embodiments of the invention can take any suitable form with a multi-layer barrier film comprising: a first PET layer; a second PET layer; an OPP layer between the first and second PET layers; a first barrier layer between the first PET layer and the OPP layer; a second barrier layer between the second PET layer and the OPP layer; and a first acrylic layer on an opposite side of the first PET layer with respect to the OPP layer. Any suitable barrier layers can be provided. In any embodiment, PET layers can be substituted for another Polyester such as Polyethylene Naphthalate (PEN). Likewise, the OPP layer can be substituted for any type of Polyolefin such as Cast Polypropylene (CPP) or Polyethylene (PE). Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications can be made without departing from the scope of the invention as defined in the appended claims. The word "comprising" can mean "including" or "consisting of" and therefore does not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A multi-layer barrier film comprising:a first Polyester layer;a second Polyester layer;a Polyolefin layer between the first and second Polyester layers;a first barrier layer between the first Polyester layer and the Polyolefin layer;a second barrier layer between the second Polyester layer and the Polyolefin layer; anda first acrylic layer on an opposite side of the first Polyester layer with respect to the Polyolefin layer,wherein each barrier layer has a gas and / or moisture transmission rate which is less than the gas and / or moisture transmission rate of the Polyester and / or Polyolefin layerswherein the first acrylic layer is a coating applied to a surface of the first Polyester layer.LDCM 2. The multi-layer barrier film of claim 1, further comprising a third Polyester layer and a third barrier layer between the first Polyester layer and the Polyolefin layer.

3. The multi-layer barrier film of claim 2, further comprising a fourth Polyester layer and a fourth barrier layer between the second Polyester layer, distinct from the first one, and the Polyolefin layer.

4. The multi-layer barrier film of any preceding claim, further comprising a second acrylic layer on an opposite side of the second Polyester layer with respect to the Polyolefin layer.

5. The multi-layer barrier film of claim 4, wherein the second acrylic layer is a coating applied to a surface of the second Polyester layer.

6. The multi-layer barrier film of any preceding claim, wherein each barrier layer is a coating applied to a respective surface of one of the Polyester layers or the Polyolefin layer.

7. The multi-layer barrier film of claim 6 when dependent on claim 3, wherein the first barrier layer is applied to a surface of the first Polyester layer between the firstPolyester layer and the third Polyester layer to form a first web, the third barrier layer is applied to the third Polyester layer between the first Polyester layer and the third Polyester layer to form a second web, the second barrier layer is applied to the second Polyester layer between the second Polyester layer and the fourth Polyester layer to form a third web and the fourth barrier layer is applied to the fourth Polyester layer between the second Polyester layer and the fourth Polyester layer to form a fourth web.

8. The multi-layer barrier film of claim 7, further comprising a fifth barrier layer applied to the third Polyester layer between the third Polyester layer and the Polyolefin layer forming part of the second web.

9. The multi-layer barrier film of claim 7 or claim 8, further comprising a sixth barrier layer applied to the fourth Polyester layer between the fourth Polyester layer and the Polyolefin layer forming part of the fourth web.LD 10. The multi-layer barrier film of any of claims 7 to 9, further comprising a C\J seventh barrier layer applied to the Polyolefin layer between the Polyolefin layer and the third Polyester layer or the fourth Polyester layer to form a fifth web.

11. The multi-layer barrier film of any of claims 7 to 10, wherein each web is joined to one or both adjacent webs by adhesive.

12. The multi-layer barrier film of any preceding claim, wherein one or more of the barrier layers comprises metal, optionally wherein all barrier layers comprise metal.

13. The multi-layer barrier film of any preceding claim, wherein one or more of the barrier layers comprises a metallised coating, optionally wherein all barrier layers comprise a metallised coating.

14. The multi-layer barrier film of any preceding claim, wherein one or more of the barrier layers comprises a metallised coating applied to a layer of cured acylate applied to the respective Polyester or Polyolefin layer, optionally wherein all barrier layers comprise a metallised coating applied to a layer of cured acylate applied to the respective Polyester or Polyolefin layer.

15. The multi-layer barrier film of any preceding claim, wherein one or each Polyester layer comprises PET and / or wherein the Polyolefin layer comprises OPP.

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