Thermal stability barrier film structure

Abstract

The present disclosure relates to a barrier packaging film comprising a polyolefin substrate layer having a thickness in the range of 10 μm to 100 μm, an inorganic coating layer, and a polymeric buffer layer positioned between the polyolefin substrate and the inorganic coating layer, the polymeric buffer layer being in direct contact with the inorganic coating layer, the inorganic coating layer comprising a wave structure characterized by an average amplitude in the range of 0.25 μm to 1.0 μm and a wavelength in the range of 2 μm to 5 μm. Also disclosed is a package (e.g., a hermetically sealed package) formed from the barrier packaging film.

Description

Technical Field

[0001] The present invention relates to a heat-stable multilayer barrier film structure. Embodiments of the present invention are directed to flexible multilayer films for packaging applications.

Background Art

[0002] A typical packaging application involving exposure of a multilayer barrier structure to thermal stress is retort packaging. In retort packaging, the packaged product undergoes a long-term heat and pressure treatment process. Similarly, the package or the packaged product may undergo a pasteurization process at about 80°C. In yet another application, the multilayer barrier structure can be used as a heat shrink wrap foil at temperatures below 80°C.

[0003] Examples of multilayer heat-shrinkable films for use as wrapping foils are disclosed in U.S. Patent Documents US2006 / 222793 and US6627274.

[0004] Food products are increasingly being packaged in flexible retort packages as an alternative to metal cans and glass bottles. Packaging materials for flexible retort packages typically include an encapsulated barrier layer, an outer polymer layer adhered to one side of the barrier layer and forming the outer surface of the package, and a heat-sealable inner polymer film layer adhered to the other side of the gas barrier layer and forming the inner surface of the package. This combination of layers is thought to be able to withstand the retort process without melting or substantially decomposing (i.e., leaking, delaminating). Generally, retort processing consists of heating the packaging container to a temperature in the range of 100 to 135°C, at an overpressure in the range of 0.5 to 1.1 bar, for a period in the range of 15 to 100 minutes.

[0005] Examples of laminates for retort packaging are disclosed in US4,310,578(A), US4,311,742(A), US4,308,084(A), US4,309,466(A), US4,402,172(A), US4,903,841(A), US5,273,797(A), US5,731,090(A), EP1466725(A1), JPH09267868(A), JP2002 / 096864(A), JP2015 / 066721(A), JP2018 / 053180(A), JP2017 / 144648(A), JPS62279944(A), JPS6328642, and JPH10244641(A).

[0006] Conventional flexible retort pouches are made of layers of different materials to achieve oxygen, water, bacteria, and flavor barrier properties. One typical option for designing an elastic retort packaging multilayer barrier film is the use of an aluminum barrier layer having a thickness of at least 5 μm, preferably exceeding 12 μm. Nevertheless, aluminum is expensive, has a high density, is prone to pinholes when the thickness is low after bending, and has the drawback of opacity. Aluminum is also known to cause problems when reheating the packaged food in a microwave oven. Furthermore, the presence of a metal layer is generally undesirable from the perspectives of recyclability and metal detection within the packaging process.

[0007] Typical examples of multilayer barrier film structures for standard retort pouches include a polyethylene terephthalate outer layer, a barrier layer, and an inner seal layer. The outer layer includes a printing layer, the barrier layer includes one or more of a metal foil, a metallized film, or a transparent barrier polymer film, and the inner layer is a heat-sealable polyolefin layer. The packaging material may also include additional polymer film layers such as a polyamide layer or the like.

[0008] In addition to the recycling problem, the presence of an integral aluminum foil poses additional challenges for making the polymer layers that make up the multilayer barrier film structure recyclable.

[0009] There is a need for a recyclable thermally stable multilayer barrier film structure for packaging without countering the associated advantages of state-of-the-art systems, where the barrier layer remains substantially crack-free during heat treatment, thereby limiting loss of the film's oxygen and water vapor barrier properties. SUMMARY OF THE INVENTION

[0010] Embodiments of the present invention advantageously provide a thermoelastic barrier film structure for packaging. In some embodiments, the thermoelastic barrier film structure is heat-treated, for example, during pasteurization or retort processing. In some embodiments, the thermoelastic barrier film structure comprises an inorganic barrier layer that remains substantially crack-free during and after heat treatment, thereby limiting an increase in the film's oxygen and water vapor transmission rates.

[0011] In one or more embodiments, the barrier film structure includes one or more inorganic coating layers in contact with at least one buffer layer within a multilayer laminate. In some embodiments, the presence of the buffer layer allows for the formation of waves in the inorganic coating layer, thereby avoiding crack formation when the substrate layer shrinks under thermal stress. The normal loss of oxygen and water vapor transmission rates in a typical barrier film structure may be reduced by the presence of the buffer layer, and the transmission rates of the flexible multilayer films described herein may remain acceptable even after heat treatment.

[0012] Additional embodiments of the present invention advantageously provide a more sustainable transparent multilayer barrier film exhibiting excellent oxygen transmission rates (low transmission, high barrier), where the oxygen transmission rates remain substantially unchanged after heat treatment, and the thermoelastic barrier film structure is relatively easier to recycle than typical high-barrier packaging structures.

[0013] Some embodiments of the barrier packaging film include a polyolefin substrate that includes free shrinkage in the range of 0.5% to 10% at 95 °C in at least one of the longitudinal and transverse directions according to ASTM D2732, an inorganic coating layer having a thickness in the range of 0.005 microns to 0.1 microns, a polymer buffer layer positioned between the polyolefin substrate and the inorganic coating layer and in direct contact with each of them, the polymer buffer layer including a thickness in the range of 0.5 microns to 12 microns, and a polyolefin seal layer. The ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating layer is in the range of 20 to 500, and the polymer buffer layer includes a Young's modulus in the range of 0.1 MPa to 100 MPa calculated from the measured values collected at 95 °C according to ASTM E2546-15 having Appendix X.4.

[0014] Some embodiments of the barrier packaging film further include an adhesive layer. In addition, the polyolefin substrate is a first outer layer, the polyolefin seal layer is a second outer layer, and the adhesive layer is positioned between the polyolefin seal layer and the inorganic coating layer. These embodiments may further include a printed label layer positioned between the polyolefin seal layer and the inorganic coating layer.

[0015] Some embodiments of the barrier packaging film further include a printed label layer and an adhesive layer. In addition, the printed label layer is a first outer layer, the polyolefin seal layer is a second outer layer, and the adhesive layer is positioned between the polyolefin seal layer and the inorganic coating layer.

[0016] In some embodiments of the barrier packaging film, the polyolefin substrate is an oriented polypropylene film and the polyolefin seal layer is a polypropylene seal layer. The oriented polypropylene film may include homopolymer polypropylene.

[0017] In some embodiments of the barrier packaging film, the polyolefin substrate is an oriented polypropylene film, and the polyolefin seal layer is a polypropylene seal layer.

[0018] Some embodiments of the barrier packaging film further comprise an oriented polyolefin outer layer and an adhesive layer. In addition, the polyolefin seal layer is a sublayer of the polyolefin substrate, and the adhesive layer is located between the oriented polyolefin outer layer and the inorganic coating layer. The barrier packaging film may also further comprise a printed indicia layer located between the oriented polyolefin outer layer and the inorganic coating layer.

[0019] In some embodiments, the barrier packaging film has a total composition comprising 80 wt% or more polyolefin, 90 wt% or more polyolefin, or 95 wt% or more polyolefin.

[0020] In some embodiments of the barrier packaging film, the polyolefin substrate comprises a thickness in the range of 10 microns to 100 microns.

[0021] In some embodiments of the barrier packaging film, the polymer buffer layer comprises a thickness in the range of 1 μm to 5 μm.

[0022] In some embodiments of the barrier packaging film, the inorganic coating layer comprises a metal layer or an oxide coating layer, and the thickness of the inorganic coating layer is in the range of 0.005 μm to 0.06 μm.

[0023] In some embodiments of the barrier packaging film, the ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating layer is in the range of 30 to 120.

[0024] In some embodiments of the barrier packaging film, the polymer substrate comprises a free shrinkage in the range of 1% to 6% at 95 °C in accordance with ASTM D2732.

[0025] In some embodiments of the barrier packaging film, the polymer buffer layer comprises a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

[0026] The barrier packaging film may further comprise a second polymer buffer layer that is in direct contact with the inorganic coating layer.

[0027] Some embodiments of the barrier packaging film include a polyolefin substrate, an inorganic coating layer, and a polymer buffer layer positioned between the polyolefin substrate and the inorganic coating layer, the polymer buffer layer being in direct contact with the inorganic coating layer, and a polyolefin seal layer. Additionally, the inorganic coating layer has a wave structure characterized by an average amplitude in the range of 0.25 μm to 1.0 μm and a wavelength in the range of 2 μm to 5 μm, and the polymer buffer layer includes a thickness in the range of 1.1 to 20 times the average amplitude of the wave structure.

[0028] The barrier packaging film including the wave structure may further comprise an adhesive layer. Additionally, the polyolefin substrate is a first outer layer, the polyolefin seal layer is a second outer layer, and the adhesive layer is positioned between the polyolefin seal layer and the inorganic coating layer. The film may further comprise a printed mark layer positioned between the polyolefin seal layer and the inorganic coating layer.

[0029] The barrier packaging film including the wave structure may further comprise a printed mark layer and an adhesive layer. Additionally, the printed mark layer is a first outer layer, the polyolefin seal layer is a second outer layer, and the adhesive layer is positioned between the polyolefin seal layer and the inorganic coating layer.

[0030] In some barrier packaging films including the wave structure, the polyolefin substrate is an oriented polypropylene film and the polyolefin seal layer is a polypropylene seal layer. The oriented polypropylene film may include homopolymer polypropylene.

[0031] In some embodiments of the barrier packaging film including a wave structure, the polyolefin substrate is an oriented polyethylene film, and the polyolefin seal layer is a polyethylene seal layer.

[0032] Some embodiments of the barrier packaging film including a wave structure further include an oriented polyolefin outer layer and an adhesive layer. Further, the polyolefin seal layer is a sub-layer of the polyolefin substrate, and the adhesive layer is located between the polyolefin outer layer and the inorganic coating layer. In addition, the barrier packaging film may further include a printed indicia layer located between the polyolefin outer layer and the inorganic coating layer.

[0033] Some embodiments of the barrier packaging film including a wave structure have a total composition comprising 80 wt% or more polyolefin, 90 wt% or more polyolefin, or 95 wt% or more polyolefin.

[0034] In some embodiments of the barrier packaging film including a wave structure, the polyolefin substrate includes a thickness in the range of 10 microns to 100 microns.

[0035] In some embodiments of the barrier packaging film including a wave structure, the polymer buffer layer includes a thickness in the range of 1 to 5 μm.

[0036] In some embodiments of the barrier packaging film including a wave structure, the inorganic coating layer includes a metal layer or an oxide coating layer, and the thickness of the inorganic coating layer is in the range of 0.005 μm to 0.06 μm.

[0037] In some embodiments of the barrier packaging film including a wave structure, the ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating layer is in the range of 30 to 120.

[0038] In some embodiments of the barrier packaging film including a wave structure, the wave structure of the inorganic layer is characterized by the ratio of the wavelength to the average amplitude, and the ratio is in the range of 2 to 20.

[0039] In some embodiments of the barrier packaging film including a wave structure, the polymer buffer layer includes a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

[0040] Some embodiments of the barrier packaging film including a wave structure further include a second polymer buffer layer in direct contact with the inorganic coating layer.

[0041] Also contemplated herein is a sealed package comprising a barrier packaging film according to any embodiment.

Brief Description of the Drawings

[0042] The present disclosure may be more fully understood in consideration of the following detailed description of various embodiments of the present disclosure in connection with the accompanying drawings.

[0043]

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DETAILED DESCRIPTION OF THE INVENTION

[0044] The drawings show some embodiments, but not all. The elements depicted in the drawings are illustrative and not necessarily to scale, and the same (or similar) reference numerals indicate the same (or similar) features throughout the drawings.

[0045] The barrier packaging film structure according to the present invention includes at least one heat-shrinkable polyolefin substrate layer, at least one inorganic coating layer, and at least one polymer buffer layer. The polymer buffer layer is in direct contact with the inorganic coating layer and is positioned between the polyolefin substrate layer and the inorganic coating layer. During exposure to a temperature high enough to shrink the packaging film, the buffer layer is configured to be a malleable interface between the shrinkable substrate layer and the rigid non-shrinking inorganic coating layer, and it is allowed to form a continuous wave structure within the inorganic coating layer on the surface of at least one polymer buffer layer. In some embodiments, the formation of the continuous wave structure substantially reduces the number of cracks in the inorganic coating layer. In some embodiments, the formation of the continuous wave structure, more specifically the shrinkable substrate layer, reduces the loss of oxygen and water vapor barrier.

[0046] In some embodiments, the wave structure forming effect of the inorganic layer on the buffer layer is obtained by a delicate balance between 1) the thickness of the polymer buffer layer, 2) the elastic modulus of the polymer buffer material at the heat treatment temperature, and 3) the thickness of the inorganic layer. Above the temperature at which the substrate layer begins to shrink (i.e., the heat treatment temperature), the buffer layer needs to have a coefficient such that it can change its shape. The shape change is a result of the shrinkage surface area on the side of the buffer layer closest to the shrinkable substrate layer and the non-shrinking surface area on the side of the buffer layer adjacent to the inorganic coating layer. Due to its low coefficient, the surface of the buffer layer adjacent to the substrate layer can move and adjust with respect to the shrinkage force. The buffer layer adjacent to the inorganic layer conforms to the wave structure so as to correspond to the unchanged surface area of the inorganic coating layer. The wave structure of the inorganic coating can be formed in one or more patterns including, but not limited to, regular (i.e., stripes), helical ribbon, and random (i.e., labyrinth). The formation of the wave structure allows the inorganic coating layer to bend, retain its original surface area, remain intact (or with few cracks) without cracks, and reduce or eliminate the deterioration of the barrier properties of the inorganic coating layer that can occur due to the shrinkage of the substrate layer.

[0047] Without limiting the present invention, the model used to explain the theoretical formation of waves in various systems can be found in Huang, ZY, Hong, W, Suo Z 2005, "Nonlinear Analysis of Wrinkles in a Film Bonded to a Compliant Substrate", Journal of the Mechanics and Physics of Solids, 53, 2101 - 2118.

[0048] Embodiments of the present invention advantageously explain the formation of wave structures and the retention of barrier properties when developing polyolefin - based packaging structures. The packaging industry is thought to be moving towards more sustainable options, including the rationalization into a narrow category of materials used. For example, one option is to design packaging structures with a high polyolefin content in order to classify the film as recyclable. Excluding non - olefinic polymers from the packaging structure often presents deficiencies in the overall performance of the packaging structure. In the case of packaging intended for heat - treatment applications such as retort or pasteurization at low temperature, polyolefin polymers are more sensitive to the application temperature. Specifically, at high temperatures, polyolefin materials may shrink more than other polymer materials and may become inappropriate as a structural component of the inorganic coating layer. Introducing the concept of the buffer layer described herein into the packaging film can reduce the adverse effects by utilizing a set of more recyclable polymer materials. As a result, the barrier packaging film described herein is more easily recyclable due to its high polyolefin content while retaining high - performance properties such as oxygen and moisture - proof barriers.

[0049] As used herein, a "polymer buffer layer" is a layer within a barrier packaging film that is directly adjacent to and in contact with an inorganic coating layer and has the function of allowing the inorganic coating layer to bend from a relatively flat cross-sectional geometry to a wave structure. The polymer buffer layer is formulated such that the material or mixture of materials is malleable in the temperature range in which the barrier packaging film slightly shrinks due to thermal exposure (e.g., 95 °C), as further described herein. The formulation of the polymer buffer layer can be directed towards achieving an elastic modulus in a suitable temperature range that allows the material to be flexible.

[0050] As used herein, layers or films that are "in direct contact" with each other or are "directly adjacent" to each other do not have any material intervening between them.

[0051] As used herein, an "inorganic coating layer" refers to a layer that includes a metal layer or an oxide coating layer. The inorganic coating layer acts as a barrier layer. The inorganic coating layer can be directly vacuum deposited (i.e., vacuum coated, vapor coated, vacuum metallized) onto the surface of the buffer layer. Alternatively, the inorganic coating layer can be deposited by a wet chemical method such as solution coating.

[0052] As described herein, the polyolefin substrate layer can be oriented. The orientation can be the result of stretching the barrier packaging film in a uniaxial orientation (longitudinal or transverse direction), or a biaxial orientation (longitudinal and transverse directions), increasing the dimensions in the longitudinal and / or transverse directions and then being able to reduce the thickness of the material. The biaxial orientation can be applied to the film simultaneously or continuously. In some embodiments, the film is stretched in one or both directions at a temperature slightly below the melting temperature of the polymer in the film. In this way, the stretching "orients" the polymer chains and changes the physical properties of the film. At the same time, the stretching thins the film. The resulting oriented film can be thinner and have significant changes in mechanical properties such as toughness, heat resistance, rigidity, tear strength, and barrier. The orientation is typically achieved by a double or triple bubble process, a tenter frame process, or an MDO process using heated rolls. A typical blown film process imparts some stretching to the film but is not considered sufficient to be oriented as described herein. The oriented film can be heat set (i.e., annealed) after orientation so that the film is relatively dimensionally stable under the high temperature conditions that can be experienced during the conversion of the retort film laminate (i.e., printing or laminating) or during the use of the laminate (i.e., heat sealing or retort sterilization). As used herein, the terms "unoriented" and "not oriented" refer to single-layer or multi-layer films, sheets, or webs that are substantially free of orientation after extrusion.

[0053] As used herein, the term "polyolefin" generally includes polypropylene and polyethylene polymers.

[0054] As used throughout this application, the term "copolymer" refers to a polymer product obtained by the polymerization reaction or copolymerization of at least two monomer species. The term "copolymer" also encompasses polymerization reactions of three or more monomer species having reaction products referred to as terpolymers, quaterpolymers, etc.

[0055] When used throughout this application, the term "polypropylene" or "PP" refers to a propylene homopolymer or copolymer, unless otherwise indicated. Such copolymers of propylene include copolymers of propylene and at least one alpha olefin, and copolymers of propylene and other units or groups. The term "polypropylene" or "PP" is used regardless of the presence or absence of substituted branched groups or other modifiers. Polypropylene includes, but is not limited to, homopolymer polypropylene, polypropylene impact copolymer, polypropylene random copolymer, propylene ethylene copolymer, ethylene propylene copolymer, maleic anhydride grafted polypropylene, and blends thereof. Various polypropylene polymers can be recycled as recycled polypropylene or recycled polyolefin.

[0056] When used throughout this application, the term "polyethylene" or "PE" refers to an ethylene homopolymer or copolymer, unless otherwise indicated. Such copolymers of ethylene include copolymers of ethylene and at least one alpha olefin, and copolymers of ethylene and other units or groups such as vinyl acetate, acid groups, acrylate groups, or others. The term "polyethylene" or "PE" is used regardless of the presence or absence of substituted branched groups. Polyethylene includes, but is not limited to, medium density polyethylene, high density polyethylene, low density polyethylene, linear low density polyethylene, ultra low density polyethylene, ethylene alpha olefin copolymer, ethylene vinyl acetate, ethylene acid copolymer, ethylene acrylate copolymer, neutralized ethylene copolymers such as ionomers, maleic anhydride grafted polyethylene, and blends thereof. Various polyethylene polymers can be recycled as recycled polyethylene or recycled polyolefin.

[0057] When used throughout this application, the term "polyester" or "PET" refers to a homopolymer or copolymer having ester linkages between monomer units. The ester linkage may be represented by the general formula [O-R-OC(O)-R’-C(O)] n wherein R and R’ are the same or different alkyl (or aryl) groups and may generally be formed from the polymerization of dicarboxylic acid and diol monomers.

[0058] As used herein, the term "polyamide" refers to amide linkages (-CONH-) occurring along the molecular chain nrefers to high molecular weight polymers, including "nylon" resins, which are well-known polymers having numerous uses including utility as packaging films. Examples of nylon polymer resins for use in food packaging and processing include nylon 66, nylon 610, nylon 66 / 610, nylon 6 / 66, nylon 11, nylon 6, nylon 66T, nylon 612, nylon 12, nylon 6 / 12, nylon 6 / 69, nylon 46, nylon 6-3-T, nylon MXD-6, nylon MXDI, nylon 12T, and nylon 6I / 6T. Examples of polyamides include nylon 4,6 (poly(tetramethylene adipamide)), nylon 6 (polycaprolactam), nylon 6,6 (poly(hexamethylene adipamide)), nylon 6,9 (poly(hexamethylene nonanediamide)), nylon 6,10 (poly(hexamethylene sebacamide)), nylon 6,12 (poly(hexamethylene dodecanediamide)), nylon 6 / 12 (poly(caprolactam cododecanediamide)), nylon 6,6 / 6 (poly(hexamethylene adipamide copolycaprolactam)), nylon 66 / 610 (produced, for example, by condensation of a mixture of nylon 66 salt and nylon 610 salt), nylon 6 / 69 resin (produced, for example, by condensation of epsilon caprolactam, hexamethylenediamine, and azelaic acid), nylon 11 (polyundecanolactam), nylon 12 (polylauryl lactam), and other nylon homopolymers and copolymers, and copolymers or mixtures thereof. Polyamides are used in films for food packaging and other applications due to their unique physical and chemical properties. Polyamides are selected as materials to improve temperature resistance, abrasion resistance, puncture strength, and / or the barrier of the film. The properties of polyamide-containing films can be modified by selecting a wide range of variables including the choice of copolymer and the conversion method (e.g., coextrusion, orientation, lamination, and coating).

[0059] As used herein, polyurethane generally refers to polymers having organic units joined by urethane linkages (-NH-(C=O)-O-).

[0060] As used herein, "polylactic acid" is a polymer made from lactic acid and having a backbone of [-C(CH3)HC(=O)O-] n

[0061] As used throughout this application, the term "vinyl alcohol copolymer" refers to a film-forming copolymer of vinyl alcohol (CH2CHOH). Examples include, but are not limited to, ethylene vinyl alcohol copolymer (EVOH), butanediol vinyl alcohol copolymer (BVOH), and polyvinyl alcohol (PVOH).

[0062] As used throughout this application, the terms "ethylene vinyl alcohol copolymer", "EVOH copolymer", or "EVOH" refer to a copolymer consisting of repeating units of ethylene and vinyl alcohol. The ethylene vinyl alcohol copolymer can be represented by the following general formula: [(CH2-CH2) n -(CH2-CH(OH))] n . The ethylene vinyl alcohol copolymer can include saponified or hydrolyzed ethylene vinyl acetate copolymer. EVOH refers to a vinyl alcohol copolymer having an ethylene comonomer and is prepared, for example, by hydrolysis of a vinyl acetate copolymer or a chemical reaction with vinyl alcohol. The ethylene vinyl alcohol copolymer can contain from 28 mole percent (or less) to 48 mole percent (or more) of ethylene.

[0063] ​As used herein, the term "layer" refers to a building block of a film that is a structure of a single material type or a homogeneous blend of materials. A layer can be a single polymer, a blend of materials within a single polymer type, or a blend of various polymers, can contain metallic materials, and can have additives. A layer can be continuous with the film or can be discontinuous or patterned. A layer has a thickness in the z-direction that is small compared to its length and width in the x-y direction, and is thus defined as having two major surfaces, the area of which is defined by the length and width of the layer. An outer layer is a layer that is connected to another layer at only one of its major surfaces. In other words, one of the major surfaces of the outer layer is exposed. An inner layer is a layer that is connected to another layer at both of its major surfaces. In other words, the inner layer is between two other layers. A layer can have sub-layers.

[0064] Similarly, as used herein, the term "film" refers to a web constructed of layers and / or films, all of which are directly adjacent to and connected to each other. A film can be described as having a thickness that is small compared to the length and width of the film. A film has two major surfaces, the area of which is defined by the length and width of the film.

[0065] As used herein, the term "outer" is used to describe a film or layer that is located on one of the major surfaces of the film in which it is provided. As used herein, the term "inner" is used to describe a film or layer that is not located on the surface of the film in which it is constructed. An inner film or layer is adjacent to another film or layer on both sides.

[0066] As used herein, the term "wave structure" refers to the cross-sectional geometry of the surface of an inorganic coating layer and an adjacent polymeric buffer layer. Similar to any wave, the wave structure has a wavelength measurable in the x-y direction and an amplitude measurable in the z direction.

[0067] The wavelength of the wave structure can be determined using a top surface microscopy technique including, but not limited to, optical microscopy, laser scanning microscopy, electron microscopy, or atomic force microscopy. The resolution of the microscope needs to be sufficient to distinguish features of the wave such as the peaks and valleys of the wave. An example of a representative top surface microscope is shown in FIG. 11. As shown in this figure, the waves take various patterns and are organized into regions or sections where the waves are regularly arranged. The wave regions intersect at corners or edges, forming irregular creases or intersections. The measurement of the waves can be performed in the wave regions, and an example thereof is shown by overlapping ellipses. Variations in the wave measurement values can occur at the intersections, and an example thereof is shown by overlapping circles because the colliding waves interfere with the regular pattern. The regions including the intersections of the waves are not used for wave measurement.

[0068] The wavelength is the distance from peak to peak or from valley to valley in a region of the wave without distortion (i.e., the wave region). The average wavelength is calculated by taking the average of at least five individual wavelength measurements.

[0069] Other techniques for determining the wavelength are possible. For example, the wavelength can be measured using a cross-sectional view of the wave structure. Another option is to use the wavelength as a grating and measure it in an optical setup. The wavelength can be determined using the spectrum of the resulting light shining through the film.

[0070] The amplitude of the wave structure (i.e., the distance from the valley to the peak of the wave) can be evaluated on the film using a z-direction information-sensitive microscope. For example, the microscope can be a laser scanning microscope or an atomic force microscope. In some embodiments, the z-direction resolution may be at least as small as in the range of several tens of nanometers.

[0071] In some embodiments of the film, the amplitude can be determined on a cut cross-section (i.e., cut with a microtome, embedded in an epoxy resin and polished, or other routes) with a microscope having appropriate resolution and contrast. The shrinkage of a laminate including many layers is generally smaller than the shrinkage of a film including only a polyolefin substrate, a polymer buffer layer, and an inorganic coating layer, so the amplitude can be lower in the above film.

[0072] As used herein, "average amplitude" is determined by measuring the amplitudes of at least five individual waves over one or more positions across a film sample in a region free of strain (i.e., the wavelength region) and calculating the average of these five measurements.

[0073] As used herein, "barrier" or "barrier film" or "barrier layer" or "barrier material" refers to providing a reduction in permeation to gases such as oxygen (i.e., containing an oxygen barrier material). The barrier material can provide a reduction in permeation to moisture (i.e., including a moisture barrier material). The barrier properties can be provided by one or more barrier materials, or a blend of multiple barrier materials. The barrier layer can provide a specific barrier necessary to store the product within the package over an extended shelf life of several months or even more than one year.

[0074] The barrier can reduce the influx of oxygen through the barrier packaging film during the shelf life of the packaged product (i.e., while the package is sealed). The oxygen transmission rate (OTR) of the barrier packaging film is an indicator of the barrier provided and can be measured in accordance with ASTM F1927 using conditions of 1 atmosphere, 23 °C, and 50% RH.

[0075] As used herein, "barrier packaging film" or "sealed package" or "retort stable package" is a film, or a package made from a film, that maintains a high oxygen or moisture barrier level with little degradation after exposure to a heat treatment temperature, at a heat treatment temperature, or after exposure above a heat treatment temperature. The package may be filled with product, sealed, and remain sealed, and thus maintain excellent barrier properties.

[0076] As used herein, "Young's modulus" or "elastic modulus" or "modulus" is a measure of the ability of a material to change dimensions under a tensile or compressive force, in units of force per unit area. Materials with a high Young's modulus may be relatively hard, and materials with a low Young's modulus may be relatively soft and flexible (i.e., elastic). Young's modulus can be calculated from a force-displacement dataset derived from a nanoindentation test procedure.

[0077] As used herein, "free shrinkage" is the unconstrained linear shrinkage that a film or layer undergoes upon exposure to a high temperature. The shrinkage is irreversible and relatively rapid (i.e., evident within seconds or minutes). Free shrinkage is expressed as a percentage of the original dimension (i.e., 100×(dimension before shrinkage - dimension after shrinkage) / (dimension before shrinkage)). Free shrinkage can be measured using ASTM D2732. Alternatively, free shrinkage can be measured by modifying the test method described in ASTM D2732 to use hot air as the heat source instead of a thermal fluid bath. When using the hot air method, an unconstrained sample is placed in an oven set to a specified temperature for at least 1 minute, allowing sufficient time for the interior of the oven and the sample to reach thermal equilibrium.

[0078] As used herein, "ASTM E2546-15 Appendix X.4" refers to an instrumented indentation test procedure according to a documented standard using an apparatus that includes a silicon tip attached to a silicon cantilever having a defined tip radius of 30 nm.

[0079] The barrier packaging film described herein may be useful as a retort or pasteurized packaging film. As used herein, "retort packaging film" or "retort packaging" refers to a film that, after being exposed to a typical retort sterilization process, is filled with a product, sealed, and remains sealed, or a package made from the film. Typical retort sterilization is a batch process that uses temperatures in the range of about 100°C to about 150°C and overpressure up to about 70 psi (483 kPa), and may have a duration of several minutes to several hours. General retort processes used for products packaged in flexible films include immersion in steam or water. Foods or other products packaged in retort packaging films and retort sterilized can be stored for long periods under ambient conditions (i.e., have storage stability) and maintain sterility. The retort process requires very special flexible packaging films to be designed to withstand the retort process, as it can decompose the film or the package made from the film.

[0080] Surprisingly, it has been found that the film structure can be developed such that the formation of a wave structure is incorporated into the inorganic coating layer upon heating of the film structure. Even upon heating, the film structure maintained the performance properties necessary for using these films for packaging applications and other similar uses. For example, the layers required for wave formation included the necessary bonding with adjacent layers, had appropriate flexibility and clarity, and were able to provide durability through other environmental conditions beyond thermal exposure (i.e., bending, puncturing, humidity, etc.).

[0081] As used herein, the term "adhesive layer" refers to a layer having the primary function of joining two adjacent layers together. The adhesive layer is positioned between two layers of a multilayer film to maintain the two layers in a predetermined position relative to each other and prevent unwanted delamination. Unless otherwise indicated, the adhesive layer can have any suitable composition that provides a desired level of adhesion to one or more surfaces in contact with the adhesive layer material.

[0082] As used herein, the term "seal layer" refers to a layer of film, sheet, etc. that is involved in sealing a film, sheet, etc., by itself and / or another layer of the same or a different film, sheet, etc. As used herein, terms such as "heat seal", "heat sealed", "heat sealing", "heat sealable", etc. refer to both a film layer that is heat sealable to itself or to another thermoplastic film layer, and the formation of a fused bond between two polymer surfaces by conventional indirect heating means. It will be understood that conventional indirect heating generates sufficient heat on at least one film contact surface for conduction to a continuous film contact surface such that the formation of a bonding interface therebetween is achieved without loss of film integrity.

[0083] As used herein, the term "printed indicia layer" refers to a layer or series of sub - layers printed on a film. The layer or sub - layers can include a pigment - containing material (i.e., colored ink), a protective layer (i.e., over - lacquer), and an ink - receptive primer. The over - lacquer can protect the printed pigment layer and can improve the appearance of the surface of the film. Each of the printed indicia layers can be continuous independently of the other layers of the film or can be discontinuous (i.e., patterned) independently. Specifically, the printed indicia layer can include one or more continuous sub - layers of white pigment printing and one or more patterned sub - layers containing other colors, whereby a visible graphic for a packaging film is produced. The printing of the printed indicia layer can be performed by any known printing method including, but not limited to, flexographic printing, gravure printing, gravure coating, and digital printing methods. The sub - layers within the printed indicia layer can be applied by the same process or using different types of processes.

[0084] As described above, the printed indicia layer can include one or more sub-layers including white pigment printing. Typically, the white pigment of the printing ink includes titanium dioxide (TiO2) particles. When the TiO2 particles are located near the inorganic oxide coating, disturbances may occur in the formation of the wave structure. Embodiments of the barrier packaging film can include one or more layers between the inorganic oxide coating layer and the printed indicia layer containing TiO2 particles. There can be other printed indicia layer sub-layers (e.g., non-white sub-layers, primer sub-layers) between the sub-layer containing TiO2 particles and the inorganic oxide coating layer. There can be an adhesive layer between the layer containing TiO2 and the inorganic oxide coating layer, such as the embodiments illustrated in FIGS. 1B and 5B. In any of the embodiments, the one or more layers between the TiO2 particle-containing layer and the inorganic oxide coating should have a combined thickness greater than or equal to the average amplitude of the wave formation.

[0085] Next, move on to specific details of embodiments of the structure of the barrier packaging film. FIG. 1A shows a cross-sectional view of a barrier packaging film 10. The barrier packaging film 10 includes a polyolefin substrate 12, an inorganic coating layer 13, and a polymer buffer layer 14 positioned between the polyolefin substrate 12 and the inorganic coating layer 13. The polymer buffer layer 14 is in direct contact with the inorganic coating layer 13. The polymer buffer layer 14 can be in direct contact with the polyolefin substrate 12 as shown in FIG. 1A, or there can be one or more additional layers between the polymer buffer layer 14 and the polyolefin substrate 12. In some embodiments, the barrier packaging film 10 also includes a polyolefin seal layer 11, a printed indicia layer 16, and an adhesive layer 15. The polyolefin substrate 12 forms the outer layer of the barrier packaging film 10, and the polyolefin seal layer 11 forms the outer layer on the opposite side of the barrier packaging film 10.

[0086] Embodiments of a barrier packaging film that include a printed indicia layer that is directly adjacent to an inorganic coating layer may include a sublayer within the printed indicia layer. The primer sublayer may be directly adjacent to the inorganic coating layer, followed by one or more pigment-containing sublayers. The primer containing the sublayer may be a continuous layer. The primer containing the sublayer may act as a second buffer layer, as discussed below.

[0087] In a further alternative embodiment, FIG. 1B shows a cross-sectional view of a similar barrier packaging film 10. Here, the locations of the printed indicia layer 16 and the adhesive layer 15 are reversed. The embodiment illustrated in FIG. 1B shows that it is possible to print the combination of the polyolefin substrate 12 / polymer buffer layer 14 / inorganic coating layer 13, or to print the polyolefin seal layer 11 prior to the lamination step. In yet another embodiment (not shown), both sections can be printed prior to lamination.

[0088] Figure 2 illustrates a cross-sectional view of a particular embodiment of the barrier packaging film 20. In FIG. 2, the barrier packaging film 20 includes a polyolefin substrate 22, an inorganic coating layer 23, and a polymer buffer layer 24 positioned between the polyolefin substrate 22 and the inorganic coating layer 23. The polymer buffer layer 24 is in direct contact with the inorganic coating layer 23. The polymer buffer layer 24 may be in direct contact with the polyolefin substrate 22 as shown in FIG. 2, or there may be one or more additional layers between the polymer buffer layer 24 and the polyolefin substrate 22. In some embodiments, the barrier packaging film 20 also includes a polyolefin seal layer 21, a printed indicia layer 26, and an adhesive layer 25. The printed indicia layer 26 forms the outer layer of the barrier packaging film 20, and the polyolefin seal layer 21 forms the outer layer on the opposite side of the barrier packaging film 20. At this location, the printed indicia layer 26 may include a heat-resistant overcoat sublayer for the purpose of protecting the pigment layer from scratches and exposure to heat sources. The advantage obtained in this embodiment is that it is possible to mass-produce unprinted (non-printed) film laminates, and then print specific graphics for each packaging application on small portions of the film. This can avoid a large amount of scrap material during the packaging film production process.

[0089] Figure 3 illustrates a cross-sectional view of another embodiment of the barrier packaging film 30. In this embodiment, the barrier packaging film 30 includes a polyolefin substrate 32, an inorganic coating layer 33, and a polymer buffer layer 34 positioned between the polyolefin substrate 32 and the inorganic coating layer 33. The polymer buffer layer 34 is in direct contact with the inorganic coating layer 33. The polymer buffer layer 34 may be in direct contact with the polyolefin substrate 32 as shown in Figure 3, or there may be one or more additional layers between the polymer buffer layer 34 and the polyolefin substrate 32. In some embodiments, the barrier packaging film 30 also includes a polyolefin seal layer 31, an oriented outer layer 37, a printed indicia layer 36, and an adhesive layer 35. In some embodiments, the polyolefin seal layer 31 is part of the polyolefin substrate 32 (i.e., its sublayer). The oriented outer layer 37 is formed from polyolefin and forms the outer layer of the barrier packaging film 30. The polyolefin seal layer 31 forms the outer layer on the opposite side of the barrier packaging film 30.

[0090] The example of the barrier packaging film 30 represented by Figure 3 includes BOPP(37) / printed indicia(36) / adhesive(35) / SiO x (33) / PU buffer(34) / multilayer MDOPP(32), and the MDOPP(32) film includes an outer layer(31) containing a polypropylene material suitable for heat sealing.

[0091] Figure 4 illustrates a cross-sectional view of another embodiment of the barrier packaging film 40. In Figure 4, the barrier packaging film 40 includes a polyolefin substrate 42, an inorganic coating layer 43, and a polymer buffer layer 44 positioned between the polyolefin substrate 42 and the inorganic coating layer 43. The polymer buffer layer 44 is in direct contact with the inorganic coating layer 43. In some embodiments, the polymer buffer layer 44 may be in direct contact with the polyolefin substrate 42, as shown in Figure 4, or there may be one or more additional layers between the polymer buffer layer 44 and the polyolefin substrate 42. In some embodiments, the barrier packaging film 40 also includes a polyolefin seal layer 41, a printed indicia layer 46, an adhesive layer 45, and a second polymer buffer layer 48. The polyolefin substrate 42 forms the outer layer of the barrier packaging film 40, and the polyolefin seal layer 41 forms the outer layer on the opposite side of the barrier packaging film 40. In some embodiments, the second polymer buffer layer 48 is in direct contact with the inorganic coating layer 43 on the opposite side of the first polymer buffer layer 44. In some embodiments, the second polymer buffer layer 48 has the same properties as the first polymer buffer layer 44 with respect to content, thickness, and physical properties. In some embodiments, the second polymer buffer layer 48 has different properties compared to the first polymer buffer layer 44. The extra buffer layer is important in a structure where both the polyolefin substrate and the polyolefin seal layer exhibit shrinkage properties at high temperatures.

[0092] In some embodiments, the polyolefin substrate has a free shrinkage value greater than zero in at least one of the longitudinal or transverse directions at 95°C. The free shrinkage of the polyolefin substrate at 95°C, or another high processing temperature to which the barrier packaging film is exposed, causes a reduction in the surface area of the polyolefin substrate. Any layer adjacent to or near the shrinkage polyolefin substrate is considered to experience a shrinkage force in the x-y direction due to the reduction in surface area.

[0093] The free shrinkage of the polyolefin substrate at 95 °C can be in the range of 0.5% to 10%, in the range of 0.5% to 8%, in the range of 1% to 10%, or in the range of 1% to 6%. The free shrinkage of the polyolefin substrate can be measured on the polyolefin substrate only (including any sub-layers that may be present). Alternatively, the free shrinkage of the polyolefin substrate can be measured together on a combination of the polyolefin substrate and the polymer buffer layer, and any intervening layer. The free shrinkage of the polyolefin substrate can be measured when the polyolefin substrate is connected to an inorganic coating layer including the polymer buffer layer and any other intervening layer.

[0094] The polyolefin substrate includes, but is not limited to, any polymer including polyethylene, polypropylene, or blends of these polymers. The polyolefin substrate can include any number of sub-layers. The sub-layers of the polyolefin substrate can include polymers within the same polymer class (i.e., all layers are various types of polypropylene polymers), or the sub-layers can be of different polymer classes. The polyolefin substrate may or may not be oriented. The polyolefin substrate can be relatively transparent, translucent, or opaque. The polyolefin substrate can have printed indicia deposited on any of its major surfaces.

[0095] The polyolefin substrate can be a film, and the film can be made by any known process, such as a blown film or a cast film. The polyolefin substrate can be a uniaxially oriented polypropylene film (MDOPP), a biaxially oriented polypropylene film (BOPP), a uniaxially oriented polyethylene film (MDOPE), or a biaxially oriented polyethylene film (BOPE). The polyolefin substrate can be made using a specific polymer and can be oriented using specific conditions to optimize the heat resistance of the film.

[0096] The polyolefin substrate can have a thickness (before shrinkage) in the range of 6 μm to 100 μm. In some embodiments, the polyolefin substrate can have a thickness in the range of 10 μm to 50 μm, or in the range of 10 μm to 30 μm.

[0097] The inorganic coating layer of the barrier packaging film can be a metal or inorganic oxide applied by a vacuum deposition process such as chemical vapor deposition or physical vapor deposition. Alternatively, the inorganic coating layer can be applied using wet chemical techniques. The inorganic coating layer is deposited on the surface of the polymer buffer layer. The inorganic coating layer is directly adjacent to and in direct contact with the polymer buffer layer.

[0098] The inorganic coating layer provides a significant contribution to the oxygen barrier (OTR reduction) for the barrier packaging film. The inorganic coating layer can be a transparent oxide coating such as AlO x (i.e., aluminum oxide) or SiO x (i.e., silicon oxide). The oxide coating can be made by a vacuum deposition process.

[0099] The inorganic coating layer can include a metal layer such as aluminum or a blend of aluminum and another metal. The metal layer can be made by a vacuum deposition process.

[0100] Referring again to FIGS. 1A, 1B, 2, 3, and 4, the inorganic coating layers 13, 23, 33, 43 have thicknesses 13A, 23A, 33A, 43A measured in the z direction. The inorganic coating layers 13, 23, 33, 43 have thicknesses 13A, 23A, 33A, 43A in the range of 0.005 μm to 0.1 μm, in the range of 0.005 μm to 0.06 μm, in the range of 0.01 μm to 0.1 μm, or in the range of 0.01 μm to 0.06 μm. An inorganic coating layer having a thickness greater than these ranges can result in a layer that cannot bend within the wave structure to accommodate changes in surface area without cracking or otherwise failing.

[0101] In some embodiments, the polymer buffer layer of the barrier packaging film is located between the polyolefin substrate and the inorganic coating layer. In some embodiments, the polymer buffer layer is in direct contact with the inorganic coating layer. The polymer buffer layer may be in direct contact with the polyolefin substrate. The polymer buffer layer may be a sublayer within the film that also includes the polyolefin substrate. In some embodiments of the barrier packaging film, an intervening layer may be present between the polymer buffer layer and the polyolefin substrate.

[0102] Without limitation, embodiments of the polymer buffer layer may include polymers such as vinyl alcohol copolymers, polyurethane-based polymers, polypropylene-based polymers, polylactic acid-based polymers, blends of these polymers, or blends of these materials with other materials. Again, without limitation, the polymer buffer layer may be made by coating, extrusion, coextrusion, or lamination. The buffer layer may have intrinsic barrier properties (oxygen or moisture barrier) that can contribute to the overall barrier properties of the barrier packaging film.

[0103] Referring again to FIGS. 1A, 1B, 2, 3, and 4, the polymer buffer layers 14, 24, 34, 44 have thicknesses 14A, 24A, 34A, 44A measured in the z-direction. The polymer buffer layers 14, 24, 34, 44 have thicknesses 14A, 24A, 34A, 44A in the range of 0.5 μm to 12 μm, in the range of 1 μm to 5 μm, or in the range of 1 μm to 2.5 μm.

[0104] The ratio of the thickness of the polymer buffer layer of the barrier packaging film to the thickness of the inorganic coating layer of the barrier packaging film is in the range of 20 to 500, or in the range of 30 to 120. The thickness ratio within this range is one of the combinations of factors that allow the formation of a wave structure within the inorganic coating layer during the shrinkage of the polyolefin substrate.

[0105] The polymer buffer layer has a Young's modulus in the range of 0.1 MPa to 100 MPa at a high temperature such as 95°C. This property of the polymer buffer layer, in conjunction with the location and thickness of the polymer buffer layer in particular among the details of the film structure, advantageously allows the formation of a wave structure in the inorganic coating layer as the polyolefin substrate shrinks, preventing cracks and losses in the barrier properties.

[0106] The polyolefin seal layer may contain a polyolefin material. The seal layer may contain a formulation of polymers designed to lower the heat seal initiation temperature and complement the heat resistance of the opposite outer layer. Even though the seal layer may have a fairly low temperature softening point, the seal layer may have sufficient integrity to withstand the high temperatures of the retort sterilization process in addition to other abuses that the package can withstand during distribution and use.

[0107] In some embodiments, the seal layer of the barrier packaging film has a composition that allows the formation of a heat seal, and thus a sealed package is formed. As used herein, the terms "heat seal" or "heat sealed" refer to two or more surfaces joined together by the application of both short-term heat and pressure or by an ultrasonic energy sealing process. Heat sealing and ultrasonic sealing are well-known and commonly used processes for creating packages and are well known to those skilled in the art.

[0108] The seal layer is necessarily on the surface of the barrier packaging film to facilitate the function of the seal. During use of the barrier packaging film within the package, the seal layer can be heat sealed to itself or to another packaging component. During heat sealing, the seal layer softens and allows the formation of a heat seal bond at a seal temperature lower than the temperature resistance of the outer layer on the opposite side of the barrier packaging film. The seal layer softens at a seal temperature lower than the heat resistance of the opposite outer layer. The seal layer is thought to soften and form a heat seal under seal conditions (time, temperature, and pressure) that do not cause excessive shrinkage or damage on the outer surface of the barrier packaging film.

[0109] The barrier packaging film is targeted to contain a large amount of polyolefin, particularly polypropylene or polyethylene, so that the barrier packaging film can be tolerated in the recycling process. Polyolefins have relatively low heat resistance compared to the materials conventionally used in packaging films (i.e., polyester, aluminum foil, polyamide). As a result of the lower heat resistance, the package is formed using a lower temperature heat seal process to avoid shrinkage or melting. The problem that the barrier packaging film disclosed herein addresses is to incorporate a seal layer having a low heat seal initiation temperature (HSIT) and high seal strength and seal toughness in order to withstand both retort or pasteurization treatment and normal distribution and handling (i.e., drop strength and burst strength). In some embodiments, the seal layer also contains materials approved for food contact during retort conditions, as directed by government agencies regarding food safety.

[0110] The seal layer may contain a material having a low heat seal initiation temperature (HSIT). In some embodiments of the retort packaging film, the seal layer contains a polypropylene copolymer having a melting temperature of 135°C or less.

[0111] The barrier packaging film may have an overall thickness of from about 63.5 μm to about 254 μm, or from about 76.2 μm to about 152.4 μm.

[0112] The structure of the barrier packaging film and any package made therefrom includes several different elements (such as a seal layer, a polyolefin substrate, an inorganic coating layer, a buffer layer, etc.), but the total composition of the film or package should have a high level of a single material type (polyolefin or especially polypropylene or polyethylene) to facilitate recycling. As used herein, the term "total composition" is used to describe the entire film structure or package. Any material, layer, or component connected to each other in any way is part of the total composition of the article. The barrier packaging film can have a high level of polyolefin-based polymer. The packaging film can have a high level of polypropylene-based polymer. The packaging film can have a high level of polyethylene-based polymer. The packaging films described herein, and any package made therefrom, can be recyclable in a polypropylene recycling process when the article contains a large amount of polypropylene-based polymer. The packaging films described herein, and any package made therefrom, can be recyclable in a polyethylene recycling process when the article contains a large amount of polyethylene-based polymer. The mixed polyolefin recycling process can also accept the relatively high level of polyolefin present in the packaging films described herein, and any package made therefrom.

[0113] The barrier packaging films described herein can have a total composition containing at least 80 wt%, at least 85 wt% or at least 90 wt% of a polyolefin-based polymer, which promotes the recyclability of the films and / or packages in which it is used. Materials that are not polyolefin-based polymers are minimized. For example, the inorganic coating layer of the barrier packaging film is a material that is not a polyolefin-based material and is therefore provided in the thinnest layer possible to function properly as a barrier. The film can also have other non-polyolefin materials, such as those located within the adhesive layer and the printed label layer.

[0114] In certain embodiments of the barrier packaging film, the film has a total composition containing at least 80 wt%, at least 85 wt%, or at least 90 wt% of a polypropylene-based polymer. In certain embodiments of the barrier packaging film, the film has a total composition containing at least 80 wt%, at least 85 wt%, or at least 90 wt% of a polyethylene-based polymer.

[0115] As described herein, combinations of film structure design elements can be used to achieve a more heat-resistant barrier packaging film. Due to the high polyolefin content, the film may be suitable for recycling in polyolefin-based recycling processes. The film may contain low levels (i.e., ≤ 5 wt%) or may essentially not contain materials such as polyester, polyamide, chlorine-containing polymers, and aluminum foil. The film may contain non-polyolefin-based polymers such as those used in adhesive layers or ink layers, but the amount of non-polyolefin-based polymers is minimized and generally includes less than 10 wt% or less than 5 wt% of the total composition. The film may contain non-polymeric materials such as barrier materials, but the amount of non-polymeric materials is minimized and generally includes less than 10 wt% or less than 5 wt% of the total composition.

[0116] As previously described herein, an increase in ambient temperature can cause the polyolefin substrate to shrink slightly in one or more directions. As the temperature rises, the polymer material softens and the tension that may have been embedded in the layer during fabrication is released. The release of tension can result in the movement and reconfiguration of polymer chains and a final change (increase or decrease) in the dimensions of the layer. A common result of the temperature increase of the polyolefin substrate is a slight decrease (i.e., shrinkage) of the substrate in at least one direction parallel to the x-y plane of the layer.

[0117] When the polyolefin substrate contracts, compressive forces are applied to other layers within the barrier packaging film, with the greatest force being applied to the adjacent layer. Other layers may also tend to contract at elevated temperatures, and the free contraction of each layer is likely to vary slightly. The greatest difference in free contraction is likely to occur when comparing the inorganic coating layer of the barrier packaging film to any polymer layer. Most inorganic coatings do not contract at the temperature at which the polyolefin substrate contracts (e.g., 95 °C or other temperature). In addition, inorganic coatings also have a very high coefficient (high rigidity) at these elevated temperatures.

[0118] Using the defined structure of one or more embodiments of the barrier packaging film described herein, at elevated temperatures, the polyolefin substrate and, optionally, other layers of the structure begin to contract. In some embodiments, closely positioned polymer buffer layers having a low coefficient at elevated temperatures experience compressive forces in the x-y direction and readily conform to the stress. As the surface area (x-y direction) of the polyolefin substrate decreases and the material polymer buffer layer is compressed, the surface of the polymer buffer layer may become slightly denser or the polymer buffer layer may become slightly thicker (z direction). However, the inorganic coating layer is not flexible (i.e., has a high coefficient and high rigidity). As a result of the compressive forces in the x-y direction from the contracting polyolefin substrate and the low coefficient of the underlying (i.e., directly adjacent) polymer buffer layer, the inorganic coating layer may tend to bend into a wave pattern, with the amplitude of the wave being formed in the z direction. The formation of the wave structure preserves the surface area of the inorganic coating layer and prevents typical cracking that would normally form under the contraction forces in the absence of a suitable polymer buffer layer.

[0119] The cross-sectional view shown in FIG. 5A illustrates a barrier packaging film 50 that is identical to that shown in FIG. 1A except that the inorganic coating layer has formed waves here. In other words, the barrier packaging film 10 of FIG. 1A has been exposed to high temperatures, inducing shrinkage of the polyolefin substrate. The barrier packaging film 50 includes a polyolefin substrate 52, an inorganic coating layer 53, and a polymer buffer layer 54 positioned between the polyolefin substrate 52 and the inorganic coating layer 53. In some embodiments, the polymer buffer layer 54 is in direct contact with the inorganic coating layer 53. The polymer buffer layer 54 can be in direct contact with the polyolefin substrate 52 as shown in FIG. 5A, or there can be one or more additional layers between the polymer buffer layer 54 and the polyolefin substrate 52. In some embodiments, the barrier packaging film 50 also includes a polyolefin seal layer 51, a printed indicia layer 56, and an adhesive layer 55. In some embodiments, the polyolefin substrate 52 forms the outer layer of the barrier packaging film 50, and the polyolefin seal layer 51 forms the outer layer on the opposite side of the barrier packaging film 50.

[0120] The cross-sectional view shown in FIG. 5B illustrates a barrier packaging film 50 that is identical to that shown in FIG. 1B except that the inorganic coating layer has formed waves here. In other words, the barrier packaging film 10 of FIG. 1B has been exposed to high temperatures, inducing shrinkage of the polyolefin substrate. Compared with FIG. 5A, the locations of the printed indicia layer 56 and the adhesive layer 55 have been exchanged.

[0121] The cross-sectional view shown in FIG. 6 illustrates a barrier packaging film 60 that is identical to that shown in FIG. 2, except that the inorganic coating layer has been corrugated here. In other words, the barrier packaging film 20 of FIG. 2 has been exposed to high temperatures, inducing shrinkage of the polyolefin substrate. In FIG. 6, the barrier packaging film 60 includes a polyolefin substrate 62, an inorganic coating layer 63, and a polymer buffer layer 64 positioned between the polyolefin substrate 62 and the inorganic coating layer 63. In some embodiments, the polymer buffer layer 64 is in direct contact with the inorganic coating layer 63. The polymer buffer layer 64 may be in direct contact with the polyolefin substrate 62 as shown in FIG. 6, or there may be one or more additional layers between the polymer buffer layer 64 and the polyolefin substrate 62. In some embodiments, the barrier packaging film 60 also includes a polyolefin seal layer 61, a printed indicia layer 66, and an adhesive layer 65. In some embodiments, the printed indicia layer 66 forms the outer layer of the barrier packaging film 60, and the polyolefin seal layer 61 forms the outer layer on the opposite side of the barrier packaging film 60.

[0122] The cross-sectional view shown in FIG. 7 illustrates a barrier packaging film 70 that is identical to that shown in FIG. 3, except that the inorganic coating layer has been corrugated here. In other words, the barrier packaging film 30 of FIG. 3 has been exposed to high temperatures, inducing shrinkage of the polyolefin substrate. In this embodiment, the barrier packaging film 70 includes a polyolefin substrate 72, an inorganic coating layer 73, and a polymer buffer layer 74 positioned between the polyolefin substrate 72 and the inorganic coating layer 73. In some embodiments, the polymer buffer layer 34 is in direct contact with the inorganic coating layer 73. The polymer buffer layer 74 can be in direct contact with the polyolefin substrate 72, as shown in FIG. 7, or there can be one or more additional layers between the polymer buffer layer 74 and the polyolefin substrate 72. In some embodiments, the barrier packaging film 70 also includes a polyolefin seal layer 71, an oriented outer layer 77, a printed indicia layer 76, and an adhesive layer 75. In some embodiments, the polyolefin seal layer 71 is part of the polyolefin substrate 72 (i.e., its sublayer). In some embodiments, the oriented outer layer 77 is formed from polyolefin and forms the outer layer of the barrier packaging film 70. In some embodiments, the polyolefin seal layer 71 forms the outer layer on the opposite side of the barrier packaging film 70.

[0123] The cross-sectional view shown in FIG. 8 illustrates a barrier packaging film 80 that is identical to that shown in FIG. 4, except that the inorganic coating layer has been corrugated here. In other words, the barrier packaging film 40 of FIG. 4 has been exposed to high temperatures, inducing shrinkage of the polyolefin substrate. In FIG. 8, the barrier packaging film 80 includes a polyolefin substrate 82, an inorganic coating layer 83, and a polymer buffer layer 84 positioned between the polyolefin substrate 82 and the inorganic coating layer 83. In some embodiments, the polymer buffer layer 84 is in direct contact with the inorganic coating layer 83. The polymer buffer layer 84 may be in direct contact with the polyolefin substrate 82 as shown in FIG. 8, or there may be one or more additional layers between the polymer buffer layer 84 and the polyolefin substrate 82. In some embodiments, the barrier packaging film 80 also includes a polyolefin seal layer 81, a printed indicia layer 86, an adhesive layer 85, and a second polymer buffer layer 88. In some embodiments, the polyolefin substrate 82 forms the outer layer of the barrier packaging film 80, and the polyolefin seal layer 81 forms the outer layer on the opposite side of the barrier packaging film 80. In some embodiments, the second polymer buffer layer 88 is in direct contact with the inorganic coating layer 83 on the opposite side of the first polymer buffer layer 84. In some embodiments, the second polymer buffer layer 88 has the same properties as the first polymer buffer layer 84 with respect to content, thickness, and physical properties.

[0124] The wave structures shown in FIGS. 5A, 5B, 6, 7, and 8 are characterized by wavelengths 53C, 63C, 73C, 83C and amplitudes 53B, 63B, 73B, 83B.

[0125] In some embodiments of the barrier packaging film with the wave structure formed, the average amplitude of the wave structure can be in the range of 0.25 μm to 1.0 μm or in the range of 0.4 μm to 1.0 μm. The wavelength of the wave structure can be in the range of 2 μm to 5 μm. The wave structure can also be characterized by the ratio of the wavelength to the average amplitude, and the ratio is in the range of 2 to 20, or in the range of 4 to 10.

[0126] In embodiments of the barrier packaging film including a wave structure formed in the inorganic coating layer, the thickness of the polymer buffer layer can be in the range of 1.1 to 20 times the average amplitude of the wave structure. In some embodiments, the thickness of the polymer buffer layer can be in the range of 1.5 to 5 times the average amplitude of the wave structure.

[0127] When the barrier packaging film includes a wave structure formed within the inorganic coating layer, the thickness of the polymer buffer layer varies along the length of the wave. In this case, the thickness of the polymer buffer layer is measured at the center point (i.e., in the wave between the peak and the trough of the wave).

[0128] In some embodiments, before exposure to high temperature conditions, the barrier packaging film can have an average oxygen transmission rate (OTR) value of 2 cm 3 / m 2 / day or less, 1 cm 3 / m 2 / day or less, 0.5 cm 3 / m 2 / day or less, or 0.1 cm 3 / m 2 / day or less (measured in accordance with ASTM F1927 using conditions of 1 atm, 23 °C, and 50% RH). In some embodiments, after exposure to a typical retort sterilization process, the barrier packaging film has an average OTR value of 2 cm 3 / m 2 / day or less, 1 cm 3 / m 2 / day or less, 0.5 cm 3 / m 2 / day or less, or 0.1 cm 3 / m 2 / day or less. The average OTR value can be close to, at, or below the minimum detectable level of the test device. A typical retort sterilization process is completed by cutting a DIN A4-sized portion of the packaging film and exposing it to a steam sterilization process at 128 °C and 2.5 bar overpressure for 60 minutes, followed by water shower cooling.

[0129] The wave structure can be formed when the barrier packaging film is exposed to a temperature exceeding 95°C. The wave structure can be formed by any type of process. For example, during or after the conversion of the barrier packaging film, the film can be heated by rollers or an oven. The rollers should be heated to a temperature having the ability to raise the temperature of the film and cause the formation of waves. Then, this film can be used for packaging applications or other uses. Alternatively, the barrier packaging film can be exposed to high temperatures during or after the material is formed within the package, the product is filled, and it is sealed. The high temperature can be part of a retort process or another type of pasteurization.

[0130] The barrier packaging film can be formed on the package regardless of the presence or absence of other packaging components. For example, the barrier packaging film 210 can be formed on the flexible stand-up pouch 200 as shown in FIG. 10. In another embodiment of the sealed package 100, the barrier packaging film 95 can be a lid material sealed to a thermoformed tray or cup as shown in FIG. 9.

[0131] The barrier packaging film disclosed herein maintains excellent barrier properties and appearance even after the film is formed on the package, filled, sealed, and subjected to a retort sterilization process.

[0132] Here, the present disclosure will be described with reference to the following examples.

[0133] Examples and Data As summarized in Table 1 below, several film structures were fabricated.

Table 1

[0134] The film structure of Example 1 was prepared by applying an aqueous polyurethane (PU) dispersion to the surface of an 18-μm biaxially oriented polypropylene film and drying the dispersion to achieve a 1.7-μm coating. A silicon oxide coating (SiO x ) was applied to the surface of the PU coating by vapor deposition. Next, a 60-μm polypropylene seal layer was adhesively laminated to the silicon oxide coating.

[0135] The film structure of Example 2 was prepared by applying an aqueous polyurethane (PU) dispersion to the surface of an 18-μm biaxially oriented polypropylene film and drying the dispersion to achieve a 1.7-μm coating. An aluminum coating was applied to the surface of the PU coating by vapor deposition. Next, a 60-μm polypropylene seal layer was adhesively laminated to the aluminum coating.

[0136] The film structures of Example 3 and Comparative Example 4 were prepared by first depositing a silicon oxide coating layer on the heat-sealing surface of a 19-μm heat-sealable biaxially oriented polypropylene (BOPP having HS). The heat-sealing layer of the BOPP film is approximately 0.7 μm thick and is a material suitable for a buffer layer. Next, a 60-μm polypropylene seal layer was adhesively laminated to the silicon oxide coating.

[0137] The film structure of Example 5 was prepared by applying an aqueous polyurethane (PU) dispersion to the surface of an 18-μm biaxially oriented polypropylene film and drying the dispersion to achieve a 1.7-μm coating. A silicon oxide coating (SiO x ) was applied to the surface of the PU coating by vapor deposition. Next, an additional layer of aqueous PU dispersion was applied to the surface of the silicon oxide coating. Next, a 60-μm polypropylene seal layer was adhesively laminated to the exposed PU buffer coating.

[0138] The film structure of Example 6 was prepared by applying an aqueous polyurethane (PU) dispersion to the surface of a 25-μm thermally stabilized biaxially oriented polypropylene film and drying the dispersion to achieve a 1.7-μm coating. A silicon oxide coating (SiO x ) was applied to the surface of the PU coating by vapor deposition. Next, a 60-μm polypropylene seal layer was adhesively laminated to the silicon oxide coating.

[0139] For each of the structures of the examples listed in Table 1 and the structures of the comparative examples, Table 2 lists the polyolefin substrate layer of the structure (or its equivalent for the comparative examples) and the free shrinkage of this layer at 95°C. In addition, Table 2 lists the polymer buffer layer of the structure at 95°C (or its equivalent for the comparative examples) and the Young's modulus of the buffer layer material.

Table 2

[0140] The Young's modulus data shown in Table 3 were collected using an atomic force microscopy (AFM) technique utilizing the PinPoint™ mode on a Park Systems NX10 AFM. To determine the mechanical Young's modulus of the polymer buffer layer, a sample of the polyolefin substrate / polymer buffer layer was mounted on a heating stage. The stage was heated to the appropriate test temperature. A silicon tip mounted on a silicon cantilever with a defined tip radius of 30 nm (SD-R30-FM, available from NanoAndMore GmbH) was used for force spectroscopy. The Young's modulus was calculated from the resulting force-displacement curve.

[0141] For each of the structures of the examples listed in Table 1 and the structures of the comparative examples, Table 3 includes the layer thickness ratio of the polymer buffer layer and the inorganic coating layer.

Table 3

[0142] Table 4 includes an overview of the waveform formation for the structures of the examples and comparative examples. The structure was heated to a temperature exceeding 95°C and then inspected for waves.

Table 4

[0143] Top microscopic photographs of some film structures are shown in FIGS. 12A, 12B, and 12C, respectively. The film shown in FIG. 12A has a structure of 18 μm BOPP / 1.7 μm PU / 0.04 μm SiO x . The film shown in FIG. 12B has a structure of 18 μm BOPP / 1.7 μm PU / 0.05 μm SiOx. The film shown in FIG. 12C has a structure of 60 μm PP / 3.5 μm adhesive layer / 18 μm BOPP / 1.7 μm PU / 0.04 μm SiO x . The polyurethane dispersion used in the structure shown in FIG. 12B has a very high Young's modulus (exceeding 900 MPa) at 95°C and thus does not meet the conditions required for waveform formation. It should be noted that the three microscopic photographs illustrated in FIGS. 12A, 12B, and 12C were not taken at the same magnification and do not show relative wave characteristics. Rather, the microscopic photographs show clear wave formation of various patterns (FIGS. 12A and 12C) and an example without wave formation including clear cracks in the inorganic coating layer (FIG. 12B).

[0144] The results of waveform formation on the barrier performance of the film structure are clear from the data in Tables 5a and 5b. Films designed to allow waveform formation during heating and shrinkage of the film have significantly less oxygen barrier loss (less increase in OTR).

Table 5a

Table 5b

[0145] Embodiments Embodiment 1: A barrier packaging film comprising a polyolefin substrate that includes free shrinkage in the range of 0.5% to 10% at 95 °C in at least one of the longitudinal and transverse directions according to ASTM D2732, an inorganic coating layer having a thickness in the range of 0.005 microns to 0.1 microns, a polymer buffer layer positioned between the polyolefin substrate and the inorganic coating layer and in direct contact with each of them, the polymer buffer layer having a thickness in the range of 0.5 microns to 12 microns, and a polyolefin seal layer, wherein the ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating layer is in the range of 20 to 500, and the polymer buffer layer includes a Young's modulus in the range of 0.1 MPa to 100 MPa calculated from the measured values collected at 95 °C according to ASTM E2546-15 having Appendix X.4.

[0146] Embodiment 2: The barrier packaging film according to Embodiment 1, further comprising an adhesive layer, wherein the polyolefin substrate is the first outer layer, the polyolefin seal layer is the second outer layer, and the adhesive layer is positioned between the polyolefin seal layer and the inorganic coating layer.

[0147] Embodiment 3: The barrier packaging film according to Embodiment 2, further comprising a printed mark layer positioned between the polyolefin seal layer and the inorganic coating layer.

[0148] Embodiment 4: The barrier packaging film according to Embodiment 1, further comprising a printed mark layer and an adhesive layer, wherein the printed mark layer is the first outer layer, the polyolefin seal layer is the second outer layer, and the adhesive layer is positioned between the polyolefin seal layer and the inorganic coating layer.

[0149] Embodiment 5: A barrier packaging film according to any one of the preceding embodiments, wherein the polyolefin base material is an oriented polypropylene film and the polyolefin seal layer is a polypropylene seal layer.

[0150] Embodiment 6: A barrier packaging film according to Embodiment 5, wherein the oriented polypropylene film contains a homopolymer polypropylene.

[0151] Embodiment 7: A barrier packaging film according to any one of Embodiments 1 to 4, wherein the polyolefin base material is an oriented polyethylene film and the polyolefin seal layer is a polyethylene seal layer.

[0152] Embodiment 8: A barrier packaging film according to Embodiment 1, further comprising an oriented polyolefin outer layer and an adhesive layer, wherein the polyolefin seal layer is a sub-layer of the polyolefin base material and the adhesive layer is located between the oriented polyolefin outer layer and the inorganic coating layer.

[0153] Embodiment 9: A barrier packaging film according to Embodiment 8, further comprising a printed indicia layer located between the oriented polyolefin outer layer and the inorganic coating layer.

[0154] Embodiment 10: A barrier packaging film according to any one of the preceding embodiments, wherein the barrier packaging film has a total composition containing 80 wt% or more of polyolefin.

[0155] Embodiment 11: A barrier packaging film according to any one of the preceding embodiments, wherein the polyolefin base material has a thickness in the range of 10 microns to 100 microns.

[0156] Embodiment 12: A barrier packaging film according to any one of the preceding embodiments, wherein the polymer buffer layer has a thickness in the range of 1 μm to 5 μm.

[0157] Embodiment 13: A barrier packaging film according to any one of the preceding embodiments, wherein the inorganic coating layer includes a metal layer or an oxide coating layer, and the thickness of the inorganic coating layer is in the range of 0.005 μm to 0.06 μm.

[0158] Embodiment 14: A barrier packaging film according to any one of the preceding embodiments, wherein the ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating layer is in the range of 30 to 120.

[0159] Embodiment 15: A barrier packaging film according to any one of the preceding embodiments, wherein the polymer substrate includes free shrinkage in the range of 1% to 6% at 95°C in accordance with ASTM D2732.

[0160] Embodiment 16: A barrier packaging film according to any one of the preceding embodiments, wherein the polymer buffer layer includes a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

[0161] Embodiment 17: A barrier packaging film according to any one of the preceding embodiments, further comprising a second polymer buffer layer in direct contact with the inorganic coating layer.

[0162] Embodiment 18: A barrier packaging film comprising a polyolefin substrate, an inorganic coating layer, a polymer buffer layer positioned between the polyolefin substrate and the inorganic coating layer and in direct contact with the inorganic coating layer, and a polyolefin seal layer, wherein the inorganic coating layer has a wave structure characterized by an average amplitude in the range of 0.25 μm to 1.0 μm and a wavelength in the range of 2 μm to 5 μm, and the polymer buffer layer includes a thickness in the range of 1.1 to 20 times the average amplitude of the wave structure.

[0163] Embodiment 19: A barrier packaging film according to Embodiment 18, further comprising an adhesive layer, wherein the polyolefin base material is the first outer layer, the polyolefin seal layer is the second outer layer, and the adhesive layer is located between the polyolefin seal layer and the inorganic coating layer.

[0164] Embodiment 20: A barrier packaging film according to Embodiment 19, further comprising a printed mark layer located between the polyolefin seal layer and the inorganic coating layer.

[0165] Embodiment 21: A barrier packaging film according to Embodiment 18, further comprising a printed mark layer and an adhesive layer, wherein the printed mark layer is the first outer layer, the polyolefin seal layer is the second outer layer, and the adhesive layer is located between the polyolefin seal layer and the inorganic coating layer.

[0166] Embodiment 22: A barrier packaging film according to any one of Embodiments 18 to 21, wherein the polyolefin base material is an oriented polypropylene film and the polyolefin seal layer is a polypropylene seal layer.

[0167] Embodiment 23: A barrier packaging film according to Embodiment 22, wherein the oriented polypropylene film contains homopolymer polypropylene.

[0168] Embodiment 24: A barrier packaging film according to any one of Embodiments 18 to 21, wherein the polyolefin base material is an oriented polyethylene film and the polyolefin seal layer is a polyethylene seal layer.

[0169] Embodiment 25: A barrier packaging film according to Embodiment 18, further comprising an oriented polyolefin outer layer and an adhesive layer, wherein the polyolefin seal layer is a sub-layer of the polyolefin base material and the adhesive layer is located between the oriented polyolefin outer layer and the inorganic coating layer.

[0170] Embodiment 26: The barrier packaging film according to Embodiment 25, further comprising a printed mark layer located between the polyolefin outer layer and the inorganic coating layer.

[0171] Embodiment 27: The barrier packaging film according to any one of Embodiments 18 to 26, wherein the barrier packaging film has a total composition containing 80% by weight or more of polyolefin.

[0172] Embodiment 28: The barrier packaging film according to any one of Embodiments 18 to 27, wherein the polyolefin base material has a thickness in the range of 10 to 100 microns.

[0173] Embodiment 29: The barrier packaging film according to any one of Embodiments 18 to 28, wherein the polymer buffer layer has a thickness in the range of 1 to 5 μm.

[0174] Embodiment 30: The barrier packaging film according to any one of Embodiments 18 to 29, wherein the inorganic coating layer includes a metal layer or an oxide coating layer, and the thickness of the inorganic coating layer is in the range of 0.005 μm to 0.06 μm.

[0175] Embodiment 31: The barrier packaging film according to any one of Embodiments 18 to 30, wherein the ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating layer is in the range of 30 to 120.

[0176] Embodiment 32: The barrier packaging film according to any one of Embodiments 18 to 31, wherein the wave structure of the inorganic layer is characterized by the ratio of the wavelength to the average amplitude, and the ratio is in the range of 2 to 20.

[0177] Embodiment 33: The barrier packaging film according to any one of Embodiments 18 to 32, wherein the polymer buffer layer includes a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

[0178] Embodiment 34: A barrier packaging film according to any one of Embodiments 18 to 33, further comprising a second polymer buffer layer in direct contact with the inorganic coating layer.

[0179] Embodiment 35: A sealed package comprising a barrier packaging film according to any one of Embodiments 1 to 34.

[0180] Embodiment 36: A barrier packaging film according to any one of the embodiments of the aforementioned barrier packaging film, comprising a printed mark layer and an inorganic coating layer including a wave structure, wherein the printed mark layer includes a sublayer containing TiO2 particles, there is at least one layer located between the sublayer containing TiO2 particles and the inorganic coating layer, and the at least one layer located between the sublayer containing TiO2 particles and the inorganic coating layer has a combined thickness equal to or greater than the average amplitude of the wave formation.

Claims

1. A barrier packaging film, comprising: a polyolefin substrate that includes free shrinkage in the range of 0.5% to 10% at 95° C. in at least one of the longitudinal and transverse directions in accordance with ASTM D2732; an inorganic coating layer having a thickness in the range of 0.005 microns to 0.1 microns; a polymer buffer layer positioned between and in direct contact with each of the polyolefin substrate and the inorganic coating layer, the polymer buffer layer including a thickness in the range of 0.5 microns to 12 microns; a polyolefin seal layer; and a ratio value of the thickness of the polymer buffer layer divided by the thickness of the inorganic coating layer is in the range of 20 to 500; the polymer buffer layer includes a Young's modulus in the range of 0.1 MPa to 100 MPa as calculated from measured values collected at 95° C. in accordance with ASTM E2546-15 having Appendix X.4; the barrier packaging film has an overall composition that includes 80 wt % or more polyolefin; A barrier packaging film.

2. Further comprising an adhesive layer, wherein the polyolefin substrate is a first outer layer, the polyolefin seal layer is a second outer layer, and the adhesive layer is positioned between the polyolefin seal layer and the inorganic coating layer. The barrier packaging film according to claim 1.

3. The barrier packaging film according to claim 2, further comprising a printed indicia layer positioned between the polyolefin seal layer and the inorganic coating layer.

4. Further comprising a printed indicia layer and an adhesive layer, wherein the printed indicia layer is a first outer layer, the polyolefin seal layer is a second outer layer, and the adhesive layer is positioned between the polyolefin seal layer and the inorganic coating layer. The barrier packaging film according to claim 1.

5. The barrier packaging film according to claim 1, wherein the polyolefin substrate is an oriented polypropylene film and the polyolefin seal layer is a polypropylene seal layer.

6. The barrier packaging film according to claim 5, wherein the oriented polypropylene film includes homopolymer polypropylene.

7. The barrier packaging film according to claim 1, wherein the polyolefin substrate is an oriented polyethylene film and the polyolefin seal layer is a polyethylene seal layer.

8. Further comprising an oriented polyolefin outer layer and an adhesive layer, wherein the polyolefin seal layer is a sub-layer of the polyolefin substrate, and the adhesive layer is located between the oriented polyolefin outer layer and the inorganic coating layer. The barrier packaging film according to claim 1.

9. The barrier packaging film according to claim 8, further comprising a printed indicia layer located between the oriented polyolefin outer layer and the inorganic coating layer.

10. The barrier packaging film according to claim 1, wherein the barrier packaging film has a total composition comprising 90 wt% or more of polyolefin.

11. The barrier packaging film according to claim 1, wherein the polyolefin substrate has a thickness in the range of 10 microns to 100 microns.

12. The barrier packaging film according to claim 1, wherein the polymer buffer layer has a thickness in the range of 1 μm to 5 μm.

13. The barrier packaging film according to claim 1, wherein the inorganic coating layer comprises a metal layer or an oxide coating layer, and the thickness of the inorganic coating layer is in the range of 0.005 μm to 0.06 μm.

14. The barrier packaging film according to claim 1, wherein the ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating layer is in the range of 30 to 120.

15. The barrier packaging film according to claim 1, wherein the polyolefin substrate comprises free shrinkage in the range of 1% to 6% at 95 °C in accordance with ASTM D2732.

16. The barrier packaging film according to claim 1, wherein the polymer buffer layer comprises a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

17. The barrier packaging film according to claim 1, further comprising a second polymer buffer layer in direct contact with the inorganic coating layer.

18. A barrier packaging film, comprising: a polyolefin substrate; an inorganic coating layer; a polymer buffer layer positioned between the polyolefin substrate and the inorganic coating layer and in direct contact with the inorganic coating layer; and a polyolefin seal layer. The inorganic coating layer has a wave structure characterized by an average amplitude in the range of 0.25 μm to 1.0 μm and a wavelength in the range of 2 μm to 5 μm. The polymer buffer layer includes an average thickness in the range of 1.1 to 20 times the average amplitude of the wave structure, The barrier packaging film has a total composition containing 80% by weight or more of polyolefin, The value of the ratio obtained by dividing the average thickness of the polymer buffer layer by the thickness of the inorganic coating layer is in the range of 30 to 120, Barrier packaging film.

19. Further comprising an adhesive layer, The polyolefin base material is a first outer layer, The polyolefin seal layer is a second outer layer, The barrier packaging film according to claim 18, wherein the adhesive layer is located between the polyolefin seal layer and the inorganic coating layer.

20. The barrier packaging film according to claim 19, further comprising a printed mark layer located between the polyolefin seal layer and the inorganic coating layer.

21. Further comprising a printed mark layer and an adhesive layer, The printed mark layer is a first outer layer, The polyolefin seal layer is a second outer layer, The barrier packaging film according to claim 18, wherein the adhesive layer is located between the polyolefin seal layer and the inorganic coating layer.

22. The barrier packaging film according to claim 18, wherein the polyolefin base material is an oriented polypropylene film and the polyolefin seal layer is a polypropylene seal layer.

23. The barrier packaging film according to claim 22, wherein the oriented polypropylene film contains homopolymer polypropylene.

24. The barrier packaging film according to claim 18, wherein the polyolefin base material is an oriented polyethylene film and the polyolefin seal layer is a polyethylene seal layer.

25. Further comprising an oriented polyolefin outer layer and an adhesive layer, The polyolefin seal layer is a sublayer of the polyolefin base material, The barrier packaging film according to claim 18, wherein the adhesive layer is located between the oriented polyolefin outer layer and the inorganic coating layer.

26. The barrier packaging film according to claim 25, further comprising a printed mark layer located between the oriented polyolefin outer layer and the inorganic coating layer.

27. The barrier packaging film according to claim 18, wherein the barrier packaging film has a total composition containing 90% by weight or more of polyolefin.

28. The barrier packaging film according to claim 18, wherein the polyolefin substrate has a thickness in the range of 10 to 100 microns.

29. The barrier packaging film according to claim 18, wherein the polymer buffer layer has an average thickness in the range of 1 to 5 μm.

30. The barrier packaging film according to claim 18, wherein the inorganic coating layer includes a metal layer or an oxide coating layer, and the thickness of the inorganic coating layer is in the range of 0.005 μm to 0.06 μm.

31. The barrier packaging film according to claim 18, wherein the wave structure of the inorganic coating layer is characterized by a ratio of the wavelength to the average amplitude, and the ratio is in the range of 2 to 20.

32. The barrier packaging film according to claim 18, wherein the polymer buffer layer includes a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

33. The barrier packaging film according to claim 18, further comprising a second polymer buffer layer in direct contact with the inorganic coating layer.

34. A sealed package comprising the barrier packaging film according to claim 18.

Images