film

Abstract

The present invention provides a polymeric film comprising a random distribution of inclusions that are incompatible with the polymeric material of the polymeric film, wherein the inclusions are present in an average number between about 0.4 and 120 inclusions per cm2 film.

Description

[0001] FILM

[0002] The present invention concerns a polymeric film, an article comprising said film and methods of identifying said film. This invention is particularly, but not exclusively, concerned with said film comprising inclusions derived from recycled material.

[0003] Polymeric films for plastic packaging films are used in a wide variety of applications, for example labelling materials, flexible packaging for consumer articles and other applications where print and / or decoration is applied to the film.

[0004] However, there has been growing concern over the environmental impact of plastic materials over the past few years and governments have embarked on regulatory programmes to promote the use of recycled content in the creation of plastic articles. For example, current measures in the EU include the EU Packaging and Packaging Waste Directive (PPWD) that has implemented targets for recycling packaging waste for 2025 and 2030, including the introduction of Plastics Packaging tax in the UK.

[0005] It is known and widely accepted that plastic that has already been used and discarded by consumers (i.e. post-consumer waste - PCW) poses a big threat to the environment. Accordingly, the demand for reusing PCW has significantly increased. For example, the incorporation of PCW materials into product packaging has increased due to consumer demand, regulatory requirements, and environmental benefits.

[0006] Films comprising recycled content are known in the art. For example, WO2021173771 describes a multi-layer film having at least 25% scrap material content, a compatibilizer and antioxidant, which is useful for the packaging of food products, wherein the scrap material includes a blend of polymers reclaimed from streams of waste and recycling.

[0007] Furthermore, WO2021151797 describes a sustainable article for packaging comprising a multilayer post-consumer resin having an inner layer and an outer layer wherein at least 50% of the inner layer comprises post-consumer resin of coloured plastic waste and wherein the outer and / or inner layer comprises a NIR detectable colourant masterbatch.

[0008] However, there is no consideration provided in any of these documents of how to verify the amount of reclaimed or recycled content in the film, or how to identify individual films. As a result of the increase in demand for film producers to incorporate recycled material into their plastic films, in combination with the introduction of stringent standards from governments worldwide (for example the introduction of taxes applied to packaging comprising less than a minimum amount of recycled plastics), there is a growing need to provide a film that can easily be identified, as well as means to verify the recycled content of plastic films, as the film passes through multiple different supply chains.

[0009] It is known in the art to mark a film as a means for identifying a film, which can be used to verify the film's content, detect counterfeits and / or detect whether a film has been tampered with. For example, EP2536638 describes a method of deliberately marking a code onto a film and imaging the precise disposition of the code with the underlying goods such that subsequent tampering of the packaged goods is identifiable. Additionally, EP2674365 describes a marking technique which deploys a laser assembly to randomly mark a film.

[0010] However, these methods are concerned solely with the addition of codes or marking on a film to provide identification, verification and anti-counterfeit measures. This requires an additional manufacturing step, thereby increasing the time and cost of manufacture.

[0011] In an attempt to mitigate against this problem, a common approach has been to include additional marking in the film, for example Zoe O. G. Schyns et al., "Recycled Plastic Content Quantified through Aggregation-Induced Emission", ACS Sustainable Chemistry & Engineering 202210 (38), 12659-12669 (DOI: 10.1021 / acssuschemeng.2c03389) describes a fluorescence-based analytical technique to determine recycled content in plastic and single use packaging. Zoe O. G. Schyns et al. further describes that alternative methods proposed for PCW content quantification rely on inconsistent comparisons of molecular weights (MWs) or molecular weight distributions of plastics before and after recycling.

[0012] There are various known methods in the art for creating voids in polymeric films, for a variety of different purposes.

[0013] For example, WQ2021 / 069690 discloses porous polypropylene films for breathable, sterilizable film applications. The formation of voids is as a result of selected p-crystall isation and the small pores with a complicated pore structure are used to ensure moisture and vapour permeability without allowing microbes to penetrate the films. CA2961692 discloses a mono-axially oriented film comprising a plurality of voids formed by a voiding agent. Voiding agents include polybutylene terephthalate, nylon, polycarbonate, polystyrene, or polymethlymethacrylate, which are used to create numerous small pores that can inhibit tear propagation.

[0014] EP3321085 discloses a cavity-containing polyester film which contains sufficient cavities to produce a white film, even when collected material is used. The film further includes the use of a polypropylene resin as a cavity generating agent and the addition of a cavity generating agent to supplement the generation of cavities, in particular for the production of a sufficiently white film.

[0015] In some instances, the number of voids is kept as low as possible. For example, JP4867556 discloses a polypropylene film which comprises a substantially filler-free polypropylene resin, in which the number of voids is kept to below 24 voids per 25cm2, preferably less than 12 voids per 25cm2.

[0016] Therefore, there remains a need for the provision of a polymeric film with a verification and / or identification means that does not require additional markings, whilst providing a film with improved environmental benefits compared to films of the art.

[0017] According to a first aspect of the present invention, there is provided a polymeric film comprising a random distribution of inclusions that are incompatible with the polymeric material of the polymeric film, wherein the inclusions are present in an average number between about 0.4 and 120 inclusions per cm2film.

[0018] The average number of inclusions may be taken over an entire width of the film, preferably at a specific point along the length of the film. Alternatively, the average may be taken over a portion of the film, for example over at least 50% of a width of the film. The number of inclusions may be over an average of at least 55%, of at least 60%, or of at least 70% of a width of the polymeric film. Measurements may be taken at a number of points on the film and the average calculated from said measurements.

[0019] In this context, the term "inclusion" is to be understood as describing an optical obscuration, i.e., something that creates an optical effect. For example, an optical obscuration may include, but is not limited to, a particle with a surrounding void that it has caused, a particle (i.e., where no void is present), a void with no visible particle or a void with partially dispersed material. The term "optical obscuration" may be understood as the visual interaction of the inclusion with the film i.e., a presence of something that creates any optical effect. Thus, the inclusion can be of any type that creates an optical effect.

[0020] The presence of inclusions has surprisingly been found to improve the traceability of the film as the inclusions create discrete areas of optical obscuration amongst the continuous polymer phase of a polymeric film. This, in turn, provides means to easily identify the film and for example, the film's recycled content.

[0021] The optical obscuration may be detectable with the naked eye or with the aid of magnification, for example with a stereo microscope. The optical obscuration may be emphasised for analysis by image analysis software. The appearance of the inclusion may vary between and amongst type of optical obscuration. The type of inclusion present in the polymeric film may be varied depending on the source of incompatible material and sorting parameters of the incompatible material prior to inclusion in the polymeric film. Sorting parameters may for example include filtration and the use of different filter sizes.

[0022] It has been found that filtration increases the dispersion of the inclusions within the polymeric film, as well as reducing the inclusion size. Therefore, use of different filter sizes may have a different effect on the inclusion dispersion and inclusion size. For example, a finer filter may lead to the additional separation of inclusions, thereby increasing the number of inclusions present in the polymeric film.

[0023] The presence of a random distribution of inclusions has surprisingly been found to improve the traceability of the film, as the random distribution of inclusions generates measurable parameters, for example a unique map or fingerprint, that allows a user or manufacturer to identify a film. This allows the unique identification of the film when it is subsequently used in any future application. This identification of the film can advantageously be used in a broad range of applications, examples of which include, but are not limited to, verifying original goods at the point of sale or at any point upstream or downstream, verifying the content of the film (e.g. the recycled content) and / or tracking the distribution and / or use of the film. This improves the security of the film because the task of copying the arrangement of the randomly distributed inclusions would be burdensome, if not impossible. The inclusions and the polymeric film form a phase segregated structure wherein a random distribution of inclusions are dispersed within the polymeric film. The inventors have advantageously found that inclusions that are incompatible with the material of the polymeric film at the manufacturing conditions can promote void formation on stretching of the film. The void formation increases the visibility of the inclusion, thereby ensuring the particles are easily identifiable. Accordingly, the inclusion may comprise particles with a surrounding void that it has caused.

[0024] The combination of a random distribution of inclusions, wherein the number of inclusions is between about 0.4 and 120 per cm2, has been found to have benefits for film identification. This can be used to either identify the goods within the film, or to identify the film itself, particularly where recognisable international standards have to be met with regards to recycled film content.

[0025] The inclusions may be present in a number between about 0.5 and 110 between about 1 and 100, between about 1.5 and 90 per cm2. The inclusions may be present in a number below 120 per cm2, preferably below 110 per cm2, more preferably below 100 per cm2and more preferably below 90 per cm2. The inclusions may be present in a number above 0.4 per cm2, preferably above 0.5 per cm2, more preferably above 1 per cm2and more preferably above 1.5 per cm2.

[0026] Several factors may affect the number of inclusions present and / or the percentage area of optical obscuration in the film. The factors may include, but are not limited to, the percentage of recycled material present, the filtration and filter size used during the filtration process, the presence of contaminants (if any) during the process, the refractive index of the resulting inclusion (i.e., if the refractive index of the inclusion is too close to the polymeric film, the inclusion may be optically invisible and therefore not identifiable) and the nature of the extrusion process when manufacturing the polymeric film (e.g., the degree of filtration of the molten extrudate, the temperature of the extruder, the viscosity of the polymers, and / or the strain velocities in both machine and / or transverse direction as the film is stretched). The thickness of the film will also affect the number of inclusions per cm2, as the thicker the film, the more likely inclusions are to overlap and therefore to appear as a single inclusion.

[0027] The number of inclusions present may increase as the percentage of recycled content in the film increases. There may be a linear relationship between inclusion number and increasing recycled content. Inclusions being present in such an amount has been found to be particularly advantageous for providing measurable parameters that may be used as a means of identification, as it is high enough to ensure a unique distribution in a measurement area but also means that each inclusion is distinct from one another. A density of inclusions greater than 120 inclusions per cm2would result in a contiguous arrangement of inclusions, whereby differentiation between inclusions would be extremely difficult and therefore unfavourable. This would affect the films ability to act as an identification means. A density of inclusions lower than 0.4 inclusions per cm2would result in a sparce distribution of inclusions and so the inclusions would not be able to provide a reliable means of film identification. The density of the inclusions may also be such that they do not interfere with reading another identifying feature underneath the film.

[0028] It should be noted that it is known in the art that cavitated films may have a white appearance. In particular, the presence of a high density of cavitating agents or particles results in a film with a white appearance as a result of the scattering of light. Particles used for this sort of cavitation typically have a small particle size in the range of between about 0.25 and 5 microns. Accordingly, voids or cavities that are created by the small particle sizes on average typically have a length of less than 20 microns, with over 50% of the voids being less than 20 microns, often over 80% of the voids being less than 20 microns. Additionally, the particles are present at such a high density and are so small that individual cavities are not visible to the naked eye and instead, the film appears white. Each cavity does therefore not in itself create an identifiable optical effect and so cannot be considered an inclusion.

[0029] The presence of cavitation to provide a white appearance would not be viable as an identification means, as the cavities are so small and are present at such high density. This is therefore different to the inclusions of the present invention, wherein the density of inclusions is between about 0.4 and 120 per cm2, such that the film has a unique identification means.

[0030] The percentage area of optical obscuration may be between about 0.1% and 15%, between about 0.1% and 12%, or between about 0.2% and 10% of the total film area. The percentage area of optical obscuration may be lower than 15%, lower than 12%, or lower than 10%. The percentage area of optical obscuration may be greater than 0.1%, or greater than 0.2%. The percentage area of optical obscuration in this range has found to be advantageous for providing measurable parameters, such that the inclusions are not in convergence with one another and thus may be used as a reliable means of identification, while also allowing features under the film to be read. The percentage area of optical obscuration can be calculated as an average from a number of different sample points on the film. If the number of inclusions increases over the optimal amount, the inclusion number seen may decrease but the total area of obscuration may be unaffected due to the convergence of inclusions with one another, which is undesirable.

[0031] The inclusions may be formed from a recycled material. The particles, where present, may be formed from a recycled material. The recycled material may be post consumer waste (PCW) or post industrial waste (PIW).

[0032] The term recycled material in accordance with the present invention is to be understood as a material from a source other than the film manufacturing process, that would otherwise be classed as waste. For example, recycled material in accordance with the invention is to be construed as a material that comprises at least a portion of material that is distinct from the material used to produce the polymeric film. For example, the recycled material may be provided from a different manufacturing location or source.

[0033] It is therefore to be understood that recycled material in accordance with the present invention is different to a material that is reclaimed from the process of preparing the polymeric film, i.e., waste film or film that has been cut off during the film preparation process (i.e., from film edges) and subsequently recovered. This recovered film may be reused in the process and is referred to as "reclaim film". Reclaim film is therefore film that has the same properties as the polymeric film that it has been taken from and so is distinct from recycled material, as defined by the present invention.

[0034] The recycled material may comprise a wide range of materials with different melting points. At least a portion of the recycled material may have a melting point higher than the melting point of at least one of the polymeric materials of the polymeric film. The melting point of at least a portion of the recycled material may be higher than the melting point of the main polymer in the polymeric film, or the main polymer in the layer of the polymeric film that contains the recycled material (i.e. the polymer present at the greatest amount). Additionally or alternatively, at least a portion of the recycled material may not melt. The inventors have advantageously found that this promotes the presence of inclusions in the resulting polymeric film as it ensures that the recycled material remains incompatible with the polymer of the film throughout the recycling process. Additionally, or alternatively, at least a portion of the recycled material may partially or wholly decompose during the film making process, particularly during the extrusion process. In such embodiments, the resulting region of the polymeric film where the recycled material has partially or wholly decomposed may change colour, for example the colour of the region may darken. This has been found to offer an increased optical contrast, thereby improving readability and thus, traceability of the film.

[0035] In some embodiments, at least a portion of the recycled material may have a decomposition temperature lower than the melting point of the main polymeric material of the polymeric film.

[0036] In some embodiments, at least a portion of the recycled material may have a melting point higher than the temperature of the extrusion process for making the polymeric film.

[0037] In embodiments where a portion of the recycled material does not have a higher melting point than the polymeric material of the polymeric film, at least a portion of the recycled material may be of a different class of material to at least one of the polymeric materials of the polymeric film. At least a portion of the recycled material may be of a different class to the main polymer in the polymeric film, or the main polymer in the layer of the polymeric film that contains the recycled material. For example, at least a portion of the recycled material may have chemical incompatibility with a polymeric material of the polymeric film, such that the recycled material has a phase that is distinct from the polymeric material. If the recycled material has a melting point equal to or lower than the melting point of the polymeric material, and does not have chemical incompatibility, the material would not be suitable for creating inclusions in the present invention.

[0038] Utilising recycled material, for example post consumer waste, in the film according to the invention provides a more environmentally friendly alternative film than films of the prior art. The film of the invention therefore advantageously resources material which would otherwise be disregarded as waste to instead provide a useful identification means within the film itself.

[0039] Post consumer waste may be defined as material generated by households or commercial, industrial and institutional facilities where end users of the product can no longer use the product for its intended purpose. Additionally, PCW materials include returns of material from the distribution chain. PCW may be collected and sorted into various streams, for example, coloured pigmented waste, white waste and clear waste prior to incorporation into the film. PCW can further be sorted into different polyolefin materials, for example polyethylene terephthalate may be separated from polyamides and other polymer types. PCW is preferably cleaned before incorporation into the film.

[0040] PCW is known to be uncontrolled and complex, containing different types of polymers, pigments, additives and contaminants and complete separation and cleaning is typically not possible. However, some cleaning and separation before creating the film is preferable. The film of the present invention may be manufactured by extruding molten virgin polymer and PCW through a die and then winding the flat sheet onto reels. The PCW may also contribute to the polymeric content of the film, in addition to creating the incompatible inclusions. The PCW may therefore contain the same polymers as that in the film.

[0041] Optionally, the resulting films may be stretched using a bubble process, on a LISI M machine or on a stenter frame to achieve enhanced mechanical properties. The inventors have found that the more vigorous the shear forces in the extruder apparatus, the better dispersed the incompatible inclusions are.

[0042] The inclusions may comprise particles that are thermodynamically incompatible with the polymer of the film, such as inorganic particles and / or particles formed from incompatible polymers. Additionally or alternatively, the inclusions may comprise bubbles or voids formed by the presence of such materials during the stretching of the film.

[0043] In particular, the inclusions may include incompatible particles that do not form a homogenous melt with the polymeric material of the film and so a void may form around any particles present. Stretching the film increases the size of the void around the particles. Both the voids and the incompatible materials themselves can be counted as an inclusion of the present invention.

[0044] The incompatible material may be selected from at least one of polyethylene terephthalate, polybutylene terephthalate, TiOj, nylon, polypropylene, polyethylene, high density polyethylene, polyether ether ketone, acrylic, co-polymers, ethylene vinyl alcohol, polyvinyl alcohol, polyurethane, nitrocellulose, cellulose, cellulose fibres, cellulose nanofibers, polystyrene, polyvinylidene chloride, polyvinyl chloride, polycarbonate, barium sulphate, silica, aluminium, aluminium oxide, metal flakes, silicates, silicone, a polar material, CaCOs or combinations thereof. In this context, the term incompatible material is to be understood as a material that is not fully molten or compatible with the polymeric film at the manufacturing conditions. For example, where the polymeric film is polypropylene, the incompatible material may not be fully molten at 250°C or 260°C. In cases where the materials are all molten at the processing temperature, compatibility is defined by the presence of a single continuous phase and incompatibility by the presence of one or more dispersed phase within the continuous phase.

[0045] In some embodiments, the inclusions may coalesce to form a pattern, such as a stripe. For example, silicone particles can form stripes on the film. Additionally or alternatively, pigment particles such as titanium dioxide can nucleate around a polar material within the film.

[0046] The film may be a multi-layer film comprising at least one core layer and at least one skin layer. Accordingly, in some embodiments the film may comprise a core layer and two skin layers, for example an inner skin layer, an outer skin layer and at least one core layer. The film may further comprise one or more intermediate layers between the core layer and a skin layer.

[0047] The film may optionally comprise functional materials for other purposes in at least one of the layers, for example, relating to the functional or aesthetic characteristics of the film.

[0048] Antiblock particles may be present in the polymeric film. At least one of the skin layers may comprise antiblock. The antiblock may be selected from any suitable material but is preferably selected from one or more of amorphous silica and clay. The presence of antiblock in a layer of the film, preferably a skin layer, does not lead to the formation of voids. Further, antiblock particles are too small to be visible, as they have a particle size of less than 8 microns, typically less than 4 microns. Accordingly, the antiblock does not contribute to the parameter of the incompatible particles that is measured for identification. Preferably, there is no antiblock in the core layer.

[0049] However, the inclusions may be present in a core layer. The presence of inclusions in the core layer has surprisingly been found to the improve the identification of the film. The inventors found that if inclusions are too close to the surface of the film, the parameter of the inclusions in the film is more difficult to measure, thereby reducing the effectiveness of the film's identification. Thus, the presence of inclusions in the core layer improves the ease of the identification. The inclusions may include a particle with a surrounding void that it has caused. The length of the void, when present, may be between about 2 to 11 times the length of the particle causing it. On average, the length of the void, when present, may be between about 3 to 10 times, 4 to 9 times, 5 to 7 times the length of the inclusion causing it. The inclusion may or may not be visible.

[0050] The voids, when present, may have an length of between about 0.02mm to 2.2mm, between about 0.05 mm to 2mm, or between about 0.06 mm to 1.8mm. The particles may have a length of between 0.01mm to 0.8mm, preferably between 0.01mm and 0.5mm.

[0051] At least 40%, at least 50%, or at least 60% of the inclusions present may have a length smaller than 0.5mm. The smallest inclusion present in the film may have a length of about 0.005mm. The largest inclusion present may have a length of about 2.5mm. The inclusion length is a measure of the maximum dimension of the inclusion.

[0052] The inclusions may have an average diameter of between about 0.005mm to 0.7mm, or between about 0.1mm to 0.6mm, or between about 0.15mm to 0.5mm. The inclusions may have an average diameter of greater than 0.005mm, greater than 0.1mm or greater than 0.15mm. The inclusions may have an average diameter of less than 0.7mm, less than 0.6mm, or less than 0.5mm. The average diameter of inclusion may be measured according to the Feret diameter method. The inventors have found that an average inclusion size of between about 0.1mm to 0.7mm advantageously provides clear measurable parameters, such as inclusions size, colour, shape, location or particle size distribution. Some inclusions may be visible to the naked eye.

[0053] The area of film measured may comprise at least 50%, at least 60%, or at least 70% of inclusions with a size of less than 0.08mm2. The smallest area covered by an inclusion may be about 0.005 mm2. The largest area covered by an inclusion may be about 0.4mm2.

[0054] The inclusions may have an average area of between about 0.01mm2to 0.2mm2, or between about 0.02mm2to 0.16mm2, or between about 0.03mm2to 0.14mm2. The inclusions may cover an average area of greater than 0.01mm2, greater than 0.02mm2or greater than 0.03mm2. The inclusions may cover an average area of less than 0.2mm2, less than 0.16mm2, or less than 0.14mm2.

[0055] The film may comprise at least 30wt%, preferably at least 40wt% and more preferably at least 50wt% of recycled material based on the total weight of the film. The incorporation of at least 30wt% of recycled material has been found to significantly reduce the environmental impact of the film, whilst still maintaining the film's desired properties.

[0056] The number of inclusions generally increases with increasing PCW content. The number of inclusions may decrease with increasing thickness, due to overlapping inclusions.

[0057] The film may comprise a combination of virgin and recycled polymer. Thus, the PCW may contribute to both the polymeric material and the incompatible particles within the film.

[0058] One or more layers of the film are formed from a polyolefin material. For example, the film may comprise at least one layer of polypropylene, preferably biaxially orientated polypropylene. The polyolefin may be a monomeric material, a copolymer or a terpolymer.

[0059] The film may be made by any process in the art, including, but not limited to, cast sheet, cast film, or blown film.

[0060] The film may be transparent, translucent or opaque, and may be uncoloured, coloured or pigmented (usually white). The film may be either glossy or matt.

[0061] The film of the present invention can be of a variety of thicknesses depending on the application requirements. For example, the thickness of the film may be from about 5 to about 240pm thick, preferably from about 12 to 100pm thick, and most preferably from about 20 to about 80pm thick.

[0062] In particular, the inventors have found that the combination of the size and density of inclusions is important to achieve the necessary parameters to identify or verify the polymeric film based on said inclusions.

[0063] The inclusions in the film may be visible to the naked eye. Accordingly, the inclusions may be visibly distinct from the polymer film. Optionally, the inclusions may be coloured. The use of visible inclusions can impart information to the user to indicate the presence of PCW in the polymer film. The inclusions in the film may be of different shapes and different colours.

[0064] In some embodiments, the film may comprise inclusions that are not visible to the naked eye. These inclusions may readily be identified using a lens, microscope, IR spectroscopy or Raman spectroscopy. Therefore, the inclusions may be detected and identified in a highly accurate manner, and / or in a manner that is less obvious to potential counterfeiters and is more difficult to replicate.

[0065] In some embodiments, the film may not be a clear film, for example the film may be a coloured or opaque film. In this embodiment, the inclusions may be readily identifiable using IR or Raman spectroscopy, even though they are not optically visible.

[0066] According to a second aspect of the present invention, there is provided an article wrapped in the film discussed herein.

[0067] The article may be easily identifiable, which can allow verification of the film content, authentication of the article wrapped in the film and detection of tampering with the article or the film.

[0068] According to a third aspect of the present invention, there is provided a banknote comprising the film discussed herein.

[0069] The banknote may comprise additional means for identification and / or other security features, for example impressions in the film. The impressions may be created by a press or the like. This may involve the embossing or debossing of the film to impart a code thereon. Other measures may include print techniques, UV inks and / or laser imprints. This arrangement adds an extra level of verification means, such that counterfeit notes can be detected easily and fraudulent activity can be minimised.

[0070] The banknote may comprise a transparent window, wherein the inclusions are present within the transparent window.

[0071] According to a fourth aspect of the invention, there is provided a packaging comprising the film discussed herein.

[0072] The packaging may be used to wrap one or more articles. The film discussed herein may therefore be a collation film. The collation film may be used in packaging tobacco products, such as cigarette packs. The collation film may be a naked collation film, which is used to package cigarette packs that are themselves individually wrapped with another film. The packaging film may be transparent, such that the articles within the packaging can be viewed. This can also allow other identifying features, such as barcodes, on the articles in the packaging to be accurately read.

[0073] The packaging according to the invention allows the items within the packaging to be authenticated, tracked or identified.

[0074] According to a fifth aspect of the invention, there is provided use of the film discussed herein for packaging.

[0075] The film may be heat sealable in order to create a packaging. The packaging may be an identifiable packaging, in that a feature of the inclusions may be recorded and used to identify the packaging.

[0076] In some embodiments the packaging may be formed entirely or substantially by the film encasing a product. The packaging may also comprise additional components, such as trays or rigid parts. In other embodiments, the film may be part of the product itself. The packaging may be substantially rigid or substantially flexible. The method is versatile in its suitability for different types of packaging.

[0077] The packaging may be food packaging or cigarette pack packaging.

[0078] According to a sixth aspect, there is provided a method creating a film identifier for a film discussed herein, comprising recording a parameter of the inclusions in the film and allocating said recorded parameter to said film. The recorded parameter thereby creates a film identifier, such that said film can be identified from a number of films by measuring said parameter.

[0079] The recorded parameter may be communicated to a central database which holds information on the film to which the recorded parameter is allocated. The recorded parameter may be used for identification / verification purposes, for example verifying recycled content, verifying goods at the point of use or verifying the lack of tampering.

[0080] The film may have a unique fingerprint associated with the random distribution of inclusions present. Verification of the recycled content of the film may therefore be achieved by comparing a measured parameter with the film records from the central database held by a film manufacturer, for example. In this way, it is possible to track the film and verify the film's properties, for example by establishing that the film contains a minimum percentage of recycled material. This, in turn, provides accountability for the film manufacturers and helps to prevent fraud. Accordingly, the method of identifying a film according to the present invention provides a certification means for identifying films according to the invention and verifying recycled content.

[0081] The method according to the invention is reliable, consistent and difficult to counterfeit, thereby providing certainty that the film being used comprises at least the minimum amount of recycled material required.

[0082] The parameter of the inclusions in an area of the film may be recorded. The area may be a specific portion of the film reel, or may be otherwise defined on the film or on the packaging or banknote made from the film. The area may be a substantial part of the film, or may be a small area.

[0083] The person wanting to identify the film may not have access to large areas of the film, depending at the stage at which the person is wanting to verify the film, and so measuring a parameter of only a portion of the film has wider applications. This may also reduce the data to be stored and may make taking the measurement easier.

[0084] The parameter of the inclusions over all the film may be recorded. In other words, the parameter may be measured over the entirety of the film, preferably during its manufacture.

[0085] This provides a unique overview of the film's properties and inclusion distribution, thereby providing a more accurate measurement.

[0086] The parameter may be based on some or all of the inclusions in the film. The parameter may be measured only of inclusions at a particular position in the recorded area, for example at a particular position on the reel or on the defined area to be recorded. Additionally or alternatively, the parameter may be measured only of a certain type of inclusion, for example an inclusion with a particle size, shape or colour.

[0087] The measured parameter may be an image of the film, which can be used as a unique fingerprint. Alternatively, an inclusion distribution of some or all of the inclusions can be measured. A property of some or all of the inclusions may also be measured, such as the colour, size and / or shape of some of the inclusions. The component materials of the inclusions could also be measured.

[0088] The measured parameter may also be a meta-data parameter, such as the inclusion size distribution of the inclusions. A parameter concerning patterns of the inclusions, such as stripes formed from coalescence of the inclusions or nucleation of inclusions around another material, may also be measured. For example, the width of the stripes or the distance between them could be measured, as could the degree of nucleation. This is particularly beneficial if a parameter of the entire film is measured.

[0089] The measured parameter can be measured using a lens, microscope, IR spectroscopy or Raman spectroscopy. The use of spectroscopy means that the measured parameter is not visible to the naked eye, improving the security of said feature.

[0090] Identification of the film may be used in authentication of the film or the goods packaged within the film, tracking the transport / distribution of the film itself or the goods packaged within the film, identifying the presence of recycled material, or confirming the amount of recycled content in the film.

[0091] The measured parameter may be used in combination with other security features to identify the film. This is particularly the case in applications such as banknotes.

[0092] In this way, it is possible to track the film through the supply chain, establish that the film or the article packaged by the film is genuine or that the film comprises the intended amount of material, for example recycled content. Therefore, the invention provides a method that is consistently accurate and easy to use, as well as being difficult to counterfeit.

[0093] According to a seventh aspect, there is provided a method of identifying a film comprising the method above and further comprising the step of measuring the parameter of one or more films and using an allocated recorded parameter to identify a particular film. Thus, a parameter of a number of films can be measured and cross-referenced with the allocated recorded parameters in order to identify the individual films. This identification can be used to verify the amount of recycled material in the film, or any other property associated with said film. According to a eighth aspect, there is provided a method of identifying whether a packaging comprising the film discussed herein has been opened, wherein the packaging comprises a seal between the film and a surface, the method comprising recording a parameter of the inclusions in one region of the film that is aligned with a reference region on the surface, allocating said recorded parameter to said packaging and measuring whether the parameter has changed to identify whether the package has been opened, wherein a change in the parameter indicates that the package has been opened.

[0094] The surface may be another region of the film itself, or it may be a different component of the packaging, such as a more rigid component. The surface may also be part of the article being packaged. The reference region is a defined region of the surface, the border of which may be denoted by ink or any other means. The film may be directly in contact with and sealed to the surface containing the reference region. Alternatively, there may be intermediate components of the packaging to which the film is sealed, such that it is aligned with the reference region.

[0095] If the package has been opened and subsequently resealed, the film will have been moved relative to the surface. It is nearly impossible to re-seal the film in exactly the same position after opening, and so the region of the film aligned with the reference region will have changed. Thus, the measured parameter (such as the inclusion distribution pattern) will also have changed. This is particularly beneficial for resealable films, although can be applied to sealable films.

[0096] The recorded parameter may be any of the recorded parameters discussed above.

[0097] The method therefore provides means for protecting the film against tampering and anti-counterfeit to a genuine film, thereby preventing fraud. Therefore, it will be easy to identify if packaging has been tampered with.

[0098] Any feature discussed in reference to one of the aspects of the present invention applies equally to all of the other aspects discussed herein.

[0099] The invention will now be more particularly described with reference to the following examples and figures, which are not intended to be limiting to the scope of protection and in which; Figure 1 shows a digital photograph of a polymeric film according to an embodiment of the invention (left) and an image where the optical obscuration of the polymeric film is emphasised (right); and

[0100] Figure 2 shows a stereo micrograph of a control polymeric film (top) and polymeric films (middle and bottom) according to embodiments of the invention.

[0101] Figure 1 (left) illustrates a digital photograph of a 50 micron thick polypropylene film comprising 30% recycled content. The polypropylene film was prepared with polymers filtered with a 600 / 400 filter pack. The recycled content in this embodiment was filtered to 50 micron prior to its introduction into the polymeric film. A digital photograph of a 25cm2area of the resulting polymeric film was imaged. The digital photograph (left) was analysed with image analysis software to highlight the optical obscuration of the inclusions present (right) so that they are easily identifiable.

[0102] The image shows multiple inclusions 1 present in the polymeric film. As can be seen by Figure 1, the inclusions are randomly distributed and distinct from one another and thus are easily identifiable.

[0103] Figure 2 shows stereomicrographs of polymeric films. The images were taken at Zoom 2 with transmitted light.

[0104] The top image is a control 30 micron film where no PCW is present and therefore no inclusions are seen. The middle two images are of a 30 micron polypropylene film comprising 30% of recycled content and the lower two images are of a 50 micron polypropylene film comprising 30% of recycled content. The recycled content in this embodiment was filtered to 50 micron prior to its introduction into the polymeric film.

[0105] The PCW in the polypropylene film creates a random distribution of inclusions that are incompatible with the polymeric film. The middle and bottom images show inclusions 2 that are randomly distributed and distinct from one another and thus are easily identifiable. Additionally, as can be seen by the images, a number of the inclusions 2 include a particle 2a with a surrounding void 2b that said particle has caused.

[0106] Various parameters of these inclusions in the film can be recorded and used to subsequently identify the film. For example, the location of the inclusions can be recorded as a fingerprint for the film. Alternatively, a feature of the inclusions themselves can be recorded, such as their size, size distribution, colour and the like.

Claims

CLAIMS1. A polymeric film comprising a random distribution of inclusions that are incompatible with the polymeric material of the polymeric film, wherein the inclusions are present in an average number between about 0.4 and 120 inclusions per cm2film.

2. The polymeric film according to Claim 1 wherein the inclusions are formed from a recycled material.

3. The polymeric film according to Claim 2 wherein the recycled material is post consumer waste.

4. The polymeric film according to any one of Claims 1 to 3 wherein at least a portion of the recycled material has a melting point higher than the melting point of the main polymeric material of the polymeric film and / or higher than the temperature of the extrusion process for making the polymeric film.

5. The polymeric film according to any one of Claims 1 to 4 wherein at least a portion of the recycled material has a decomposition temperature lower than the melting point of the main polymeric material of the polymeric film and / or lower than the temperature of the extrusion process for making the polymeric film.

6. The polymeric film according to any one of Claims 1 to 5 wherein the percentage area of optical obscuration may be between about 0.1% and 15%, between about 0.1% and 12%, or between about 0.2% and 10% total film obscuration.

7. The polymeric film according to any one of Claims 1 to 6 wherein the inclusions are present in a number between 0.5 and 110, between about 1 and 100, between about 1.5 and 90 per cm2.

8. The polymeric film according to any one of Claims 1 to 7 wherein the inclusions have an average diameter of between about 0.005mm to 0.7mm, or between about 0.1mm to 0.6mm, or between about 0.15mm to 0.5mm.

9. The polymeric film according to any one of Claims 1 to 8 wherein the inclusions have an average area of between about 0.01mm2to 0.2mm2, or between about 0.02mm2to 0.16mm2, or between about 0.03mm2to 0.14mm2.

10. The polymeric film according to any one of Claims 1 to 9 wherein the inclusions are thermodynamically incompatible with the polymer of the film such as inorganic particles and / or particles formed from incompatible polymers, and / or wherein the inclusions are bubbles formed by the presence of such materials during the stretching of the film.

11. The polymeric film according to any one of Claims 1 to 10 wherein the incompatible material is selected from at least one of polyethylene terephthalate, polybutylene terephthalate, TiOj, nylon, polypropylene, polyethylene, high density polyethylene, polyether ether ketone, acrylic, co-polymers, ethylene vinyl alcohol, polyvinyl alcohol, polyurethane, nitrocellulose, cellulose, cellulose fibres, cellulose nanofibers, polystyrene, polyvinylidene chloride, polyvinyl chloride, polycarbonate, barium sulphate, silica, aluminium, aluminium oxide, metal flakes, silicates, silicone, a polar material, CaCOs, or combinations thereof.

12. The polymeric film according to any one of Claims 1 to 11 wherein the film is a multi-layer film comprising at least one core layer and at least one skin layer.

13. The polymeric film according to Claim 12 wherein the inclusions are present in the core layer.

14. The polymeric film according to any one of Claims 1 to 13 wherein the film comprises at least 30wt% of recycled material based on the total weight of the film.

15. The polymeric film according to any one of Claims 1 to 14 wherein the film comprises polypropylene, preferably biaxially orientated polypropylene.

16. The polymeric film according to any one of Claims 1 to 15 wherein the inclusions in the film are visible to the naked eye.

17. An article wrapped in the film according to any one of Claims 1 to 16.

18. A banknote comprising a film according to any one of Claims 1 to 16.

19. A packaging comprising a film according to any one of Claims 1 to 16.

20. Use of the film according to any one of Claims 1 to 16 for packaging.

21. The use of Claim 20 wherein the packaging is food packaging.

22. A method of creating a film identifier for a film according to any one of Claims 1 to 16, comprising recording a parameter of the inclusions in the film and allocating said recorded inclusion to said film, such that said film can be identified from a number of films by measuring said parameter.

23. The method of Claim 22, wherein a parameter of the inclusions in an area of the film is recorded.

24. The method of Claim 22, wherein a parameter of the inclusions over all of the film is recorded.

25. The method of any one of Claims 22 to 24, wherein the parameter is based on some of the inclusions in the film, optionally wherein the parameter is measured only of inclusions at a particular position in the recorded area and / or wherein the parameter is measured only of a certain type of inclusion.

26. The method of any one of Claims 22 to 24, wherein the parameter is based on all of the inclusions in the film.

27. The method of any one of Claims 22 to 25, wherein the parameter is an image of the film, an inclusion distribution of some or all of the inclusions, a property of some or all of the inclusions, or a meta-data parameter, such the inclusion size distribution of the inclusions.

28. The method of Claims 22 to 27, wherein the identification of the film is used in authentication, tracking or to confirm the amount of recycled content in the film.

29. A method of identifying a film comprising the method of any one of Claims 22 to 28 and further comprising the step of measuring the parameter of one or more films and using an allocated recorded parameter to identify a particular film.

30. A method of identifying whether a packaging comprising the film of Claims 1 to 16 has been opened, wherein the packaging comprises a seal between the film and a surface, the method comprising recording a parameter of the inclusions in one region of the film that is alignedwith a reference region on the surface, allocating said recorded parameter to said packaging and measuring whether the parameter has changed to identify whether the package has been opened, wherein a change in the parameter indicates that the package has been opened.

Images