Thermally stable barrier film structure

Abstract

This disclosure relates to a barrier packaging film comprising: a polyolefin substrate layer with a thickness ranging from 10 μm to 100 μm; an inorganic coating; and a polymer buffer layer positioned between the polyolefin substrate and the inorganic coating, the polymer buffer layer being in direct contact with the inorganic coating, wherein the inorganic coating comprises a waveform structure characterized by an average amplitude ranging from 0.25 μm to 1.0 μm and a wavelength ranging from 2 μm to 5 μm. Packaging (e.g., an airtight package) formed from the barrier packaging film is also disclosed.

Description

Technical Field

[0001] This invention relates to thermally stable multilayer barrier film structures. Embodiments of this invention relate to flexible multilayer films for packaging applications. Background Technology

[0002] A typical packaging application involving the exposure of multi-layer barrier structures to thermal stress is retort packaging. In retort packaging, the packaged product undergoes a prolonged heat and pressure treatment process. Similarly, packaging or packaged products may undergo pasteurization at approximately 80°C. In yet another application, the multi-layer barrier structure may be used as a heat-shrink wrapping foil at 80°C or lower.

[0003] Examples of multilayer heat-shrinkable films for use as wrapping foils are disclosed in US patent documents US2006222793 and US6627274.

[0004] Food products are increasingly being packaged in flex retort pouches as an alternative to metal cans and glass jars. Packaging materials used in flex retort pouches typically include an embedded 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 believed to withstand the retort process without melting or significant degradation (i.e., leakage, delamination). Typically, retort involves heating the packaging container to a temperature ranging from 100 to 135°C under an overpressure ranging from 0.5 to 1.1 bar for a duration ranging from 15 to 100 minutes.

[0005] US 4,310,578 A, US 4,311,742 A, US 4,308,084 A, US 4,309,466 A, US 4,402,172 A, US 4,903,841 A, US 5,273,797 A, US 5,731,090 A, EP 1 466 725 A1, JPH 09 267868 A, JP 2002 096 864 A, JP 2015 066 721 A, JP 2018 053 ​​180 A, JP 2017 144 648A, JPS 62 279 944 A, JPS 6 328 642 and JPH 10 244 641 Examples of laminates used in retort packaging are disclosed in A.

[0006] Conventional flexible retort pouches are manufactured using layers of different materials to achieve barriers against oxygen, water, bacteria, and flavor. A typical option for designing multi-layered barrier films for flexible retort packaging is to use an aluminum barrier layer with a thickness of at least 5 μm, preferably greater than 12 μm. However, aluminum is expensive, dense, prone to pinholes at lower thicknesses after flexing, and opaque. It is also known that aluminum can cause problems when reheating packaged food products in a microwave oven. Furthermore, the presence of a metal layer is generally undesirable in terms of recycling potential and metal detection during the packaging process.

[0007] A typical example of a multilayer barrier film structure used in standard retort pouches includes a polyethylene terephthalate outer layer, a barrier layer, and an inner sealing layer, wherein the outer layer includes a printed 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. Packaging materials may also contain additional polymer film layers such as polyamide layers.

[0008] In addition to recycling issues, the presence of integrated aluminum foil leads to an additional challenge in making these multilayer barrier membrane structures recyclable due to the diversity of polymer layers that constitute them.

[0009] Without questioning the relevant advantages of existing technology systems, there is a need for a recyclable, thermally stable multilayer barrier membrane structure for packaging, in which the barrier layers remain substantially crack-free during heat treatment, thereby limiting the loss of the membrane's oxygen and water vapor barrier properties. Summary of the Invention

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

[0011] In one or more embodiments, the barrier membrane structure includes one or more inorganic coatings in contact with at least one buffer layer in the multilayer composite. In some embodiments, the presence of the buffer layer allows for the formation of waveforms within the inorganic coating, thereby preventing cracking when the substrate layer shrinks under thermal stress. Due to the presence of the buffer layer, the loss of oxygen and water vapor permeability, common in typical barrier membrane structures, can be reduced, and the permeability of the flexible multilayer membranes described herein remains acceptable even after heat treatment.

[0012] Another embodiment of the invention advantageously provides a more sustainable transparent multilayer barrier membrane exhibiting outstanding oxygen permeability (low permeability, high barrier), which remains substantially unchanged after heat treatment. This resilient thermal barrier membrane structure is relatively easier to recycle than typical high-barrier packaging structures.

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

[0014] Some embodiments of the barrier packaging film also include an adhesive layer. Additionally, a polyolefin substrate forms a first outer layer, a polyolefin sealing layer forms a second outer layer, and the adhesive layer is located between the polyolefin sealing layer and the inorganic coating. These embodiments may also include a printed marking layer located between the polyolefin sealing layer and the inorganic coating.

[0015] Some embodiments of the barrier packaging film also include a printed marking layer and an adhesive layer. Additionally, the printed marking layer is a first outer layer, the polyolefin sealing layer is a second outer layer, and the adhesive layer is located between the polyolefin sealing layer and the inorganic coating.

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

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

[0018] Some embodiments of the barrier packaging film also include an oriented polyolefin outer layer and an adhesive layer. Additionally, the polyolefin sealing layer is a sublayer of the polyolefin substrate, and the adhesive layer is located between the oriented polyolefin outer layer and the inorganic coating. The barrier packaging film may also include a printed marking layer located between the oriented polyolefin outer layer and the inorganic coating.

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

[0020] In some embodiments of the barrier packaging film, the polyolefin substrate has a thickness ranging from 10 micrometers to 100 micrometers.

[0021] In some embodiments of the barrier packaging film, the polymer buffer layer has a thickness ranging from 1µm to 5µm.

[0022] In some embodiments of the barrier packaging film, the inorganic coating includes a metal layer or an oxide coating and the thickness of the inorganic coating 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 is in the range of 30 to 120.

[0024] In some embodiments of the barrier packaging film, the polymer substrate has a free shrinkage range of 1% to 6% at 95°C according to 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 also include a second polymer buffer layer that is in direct contact with the inorganic coating.

[0027] Some embodiments of the barrier packaging film include: a polyolefin substrate, an inorganic coating, a polymer buffer layer positioned between the polyolefin substrate and the inorganic coating, a polymer buffer layer in direct contact with the inorganic coating, and a polyolefin sealing layer. Additionally, the inorganic coating includes a waveform 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 has a thickness in the range of 1.1 to 20 times the average amplitude of said waveform structure.

[0028] The barrier packaging film, including its corrugated structure, may also include an adhesive layer. Additionally, a polyolefin substrate forms a first outer layer, a polyolefin sealing layer forms a second outer layer, and the adhesive layer is located between the polyolefin sealing layer and the inorganic coating. The film may also include a printed marking layer located between the polyolefin sealing layer and the inorganic coating.

[0029] The barrier packaging film, including the corrugated structure, may also include a printed marking layer and an adhesive layer. Furthermore, the printed marking layer is the first outer layer, the polyolefin sealing layer is the second outer layer, and the adhesive layer is located between the polyolefin sealing layer and the inorganic coating.

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

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

[0032] Some embodiments of the barrier packaging film, including the corrugated structure, also include an oriented polyolefin outer layer and an adhesive layer. Furthermore, the polyolefin sealing layer is a sublayer of the polyolefin substrate, and the adhesive layer is located between the polyolefin outer layer and the inorganic coating. Additionally, the barrier packaging film may also include a printed marking layer located between the polyolefin outer layer and the inorganic coating.

[0033] Some embodiments of barrier packaging films, including those with a wave-like structure, have a total composition comprising 80% or more, 90% or more, or 95% or more polyolefin by weight.

[0034] In some embodiments of barrier packaging films including those with a corrugated structure, the polyolefin substrate has a thickness ranging from 10 micrometers to 100 micrometers.

[0035] In some embodiments of barrier packaging films that include a wave-shaped structure, the polymer buffer layer has a thickness in the range of 1 to 5 µm.

[0036] In some embodiments of barrier packaging films including wave-shaped structures, the inorganic coating comprises a metal layer or an oxide coating and the thickness of the inorganic coating is in the range of 0.005 μm to 0.06 μm.

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

[0038] In some embodiments of barrier packaging films that include waveform structures, the waveform structure of the inorganic layer is characterized by a ratio of wavelength to average amplitude, said ratio being in the range of 2 to 20.

[0039] In some embodiments of barrier packaging films that include a wave-shaped structure, the polymer buffer layer comprises a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

[0040] Some embodiments of barrier packaging films, including those with a wave-like structure, also include a second polymer buffer layer in direct contact with the inorganic coating.

[0041] This article also discusses airtight packaging including barrier packaging films according to any implementation scheme. Attached Figure Description

[0042] This disclosure will be more fully understood by considering the following detailed description of various embodiments thereof, taken in conjunction with the accompanying drawings, in which: Figure 1A , 1B Figures 2, 3, 4, 5A, 5B, 6, 7, and 8 are cross-sectional views of different embodiments of the barrier packaging film; Figure 9 and 10 A perspective view of an embodiment of an airtight, sealed package including a barrier packaging film; Figure 11 A top view at a certain magnification of the waveform structure formed in one or more embodiments of the barrier packaging film; and Figure 12A , 12B Enlarged micrographs of top views of the films that form waveforms (12A and 12C) and the comparative film that does not form waveforms (12B). Figure 12A , 12B The photomicrograph shown in 12C is not at the same magnification.

[0043] The accompanying drawings illustrate some, but not all, of the embodiments. The elements depicted in the drawings are illustrative and not necessarily drawn to scale, and throughout the drawings, the same (or similar) reference numerals denote the same (or similar) features. Detailed Implementation

[0044] The barrier packaging film structure according to the invention comprises at least one heat-shrinkable polyolefin substrate layer, at least one inorganic coating, and at least one polymer buffer layer, the polymer buffer layer being in direct contact with the inorganic coating and positioned between the polyolefin substrate layer and the inorganic coating. During exposure to temperatures sufficiently high to cause shrinkage of the packaging film, the buffer layer is configured as a stretchable interface between the shrinkable substrate layer and the rigid, non-shrinkable inorganic coating, thereby allowing the formation of a continuous wave-like structure within the inorganic coating at the surface of the at least one polymer buffer layer. In some embodiments, the formation of the continuous wave-like structure significantly reduces the number of cracks within the inorganic coating. In some embodiments, the formation of the continuous wave-like structure and, more particularly, the shrinkable substrate layer mitigates the loss of oxygen and water vapor barriers.

[0045] In some implementations, the waveform structure formation effect of the inorganic layer on the buffer layer is achieved through 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. At or above the temperature at which the substrate layer begins to shrink (i.e., the heat treatment temperature), the buffer layer must have a modulus that allows it to change shape. This shape change is a result of the shrinking surface area on the side of the buffer layer closest to the shrinking substrate layer and the non-shrinking surface area on the side of the buffer layer adjacent to the inorganic coating. Due to its low modulus, the surface of the buffer layer adjacent to the substrate layer can move and adjust in response to shrinkage forces. The buffer layer adjacent to the inorganic layer conforms to the waveform structure to accommodate the constant surface area of ​​the inorganic coating. The waveform structure of the inorganic coating can form one or more patterns, including but not limited to regular (i.e., stripes), herringbone, and random (i.e., intricate). The formation of the waveform structure allows the inorganic coating to flex, retain its original surface area and remain intact, without cracks (or with fewer cracks), and reduces or eliminates the potential degradation of the barrier properties of the inorganic coating due to the shrinkage of the substrate layer.

[0046] Without limiting the invention, models for the theoretical formation of waveforms in various systems can be found in Huang, ZY, Hong, W, Suo Z 2005, 'Nonlinear Analysis of Wrinkles in a FilmBonded to a Compliant Substrate'. Journal of the Mechanics and Physics of Solids, 53, 2101-2118.

[0047] Embodiments of the present invention advantageously describe the formation of a corrugated structure and the retention of barrier properties when developing polyolefin-based packaging structures. The packaging industry is believed to be moving toward more sustainable options, including streamlining the materials used to a narrower category. For example, one option is to design packaging structures with high polyolefin content to classify the film as recyclable. Eliminating non-olefin polymers from packaging structures often results in deficiencies in the overall performance of the packaging structure. In the case of packaging intended for heat-treated applications such as retorting or pasteurization, polyolefin polymers are more sensitive to the application temperature. Specifically, at high temperatures, polyolefin materials can shrink more than other polymer materials and may become unsuitable as structural components of inorganic coatings. Introducing the buffer layer concept, as described herein, into packaging films can mitigate the negative impacts of using a more recyclable set of polymer materials. Therefore, the barrier packaging films described herein are easier to recycle due to their high polyolefin content, while still retaining high-performance properties such as oxygen and moisture barrier properties.

[0048] As used herein, a “polymer buffer layer” is a layer within a barrier packaging film that is directly adjacent to and in contact with the inorganic coating, and which allows the inorganic coating to flex from a relatively flat cross-sectional geometry into a wave-like structure. The polymer buffer layer is formulated such that the material or blend of materials becomes stretchable within a temperature range in which the barrier packaging film undergoes slight shrinkage due to heat exposure (e.g., 95°C), as further described herein. The formulation of the polymer buffer layer can be designed to achieve an elastic modulus that allows the material to remain flexible within a suitable temperature range.

[0049] As used in this article, layers or films that are “in direct contact” or “directly adjacent” to each other have no intermediate material between them.

[0050] As used herein, "inorganic coating" refers to a layer comprising a metallic layer or an oxide coating. Inorganic coatings act as barrier layers. Inorganic coatings can be directly vacuum deposited (i.e., vacuum coating, vapor phase coating, vacuum metallization) onto the surface of a buffer layer. Alternatively, inorganic coatings can be deposited using wet chemical methods, such as solution coating.

[0051] As described herein, the polyolefin substrate layer can be oriented. Orientation can be the result of uniaxial (longitudinal or transverse) or biaxial (longitudinal and transverse) stretching of the barrier packaging film, thereby increasing the longitudinal and / or transverse dimensions and subsequently reducing the thickness of the material. Biaxial orientation can be imparted to the film simultaneously or sequentially. In some embodiments, the film is stretched in one or both directions at a temperature just below the melt temperature of the polymer within the film. In this manner, stretching causes the polymer chains to "orient," thereby altering the physical properties of the film. Simultaneously, stretching thins the film. The resulting oriented film is thinner, and mechanical properties such as toughness, heat resistance, stiffness, tear strength, and barrier properties may change significantly. Orientation is typically achieved via double-bubble or triple-bubble methods, via tenter frame methods, or via MDO methods using heated rollers. Typical blown film methods do impart some stretch to the film, but not enough to be considered oriented as described herein. Oriented films can be heat-set (i.e., annealed) after orientation, so that the film is relatively dimensionally stable under elevated temperature conditions that may be experienced during the conversion of the film laminate (i.e., printing or lamination) or during the use of the laminate (i.e., heat sealing or sterilization). As used herein, the terms “unoriented” and “non-oriented” refer to single-layer or multi-layer films, sheets or webs that are substantially not oriented after extrusion.

[0052] As used herein, the term "polyolefin" generally includes polymers of polypropylene and polyethylene.

[0053] As used throughout this application, the term "copolymer" refers to a polymer product obtained by polymerization or copolymerization of at least two monomer species. The term "copolymer" also includes polymerization reactions of three, four, or more monomer species having reaction products called ternary copolymers, quaternary copolymers, etc.

[0054] As used throughout this application, unless otherwise stated, the term "polypropylene" or "PP" refers to a propylene homopolymer or copolymer. Such propylene copolymers include copolymers of propylene with at least one α-olefin and copolymers of propylene with other units or groups. The use of the term "polypropylene" or "PP" does not take into account the presence or absence of substituents, branched groups, or other modifiers. Polypropylene includes, but is not limited to, homopolymer polypropylene, polypropylene impact copolymers, polypropylene random copolymers, propylene-ethylene copolymers, ethylene-propylene copolymers, maleic anhydride-grafted polypropylene, and blends thereof. Various polypropylene polymers can be recycled as recycled polypropylene or recycled polyolefins.

[0055] As used throughout this application, unless otherwise stated, the term "polyethylene" or "PE" refers to ethylene homopolymers or copolymers. Such ethylene copolymers include copolymers of ethylene with at least one α-olefin and copolymers of ethylene with other units or groups such as vinyl acetate, acid groups, acrylate groups, etc. The use of the term "polyethylene" or "PE" does not take into account the presence or absence of substituent 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 α-olefin copolymers, ethylene vinyl acetate, ethylene-acrylic acid copolymers, ethylene-acrylate copolymers, neutralized ethylene copolymers such as ionomers, maleic anhydride-grafted polyethylene, and blends thereof. Various polyethylene polymers can be recycled as recycled polyethylene or recycled polyolefins.

[0056] As used throughout this application, the terms "polyester" or "PET" refer to homopolymers or copolymers in which ester bonds exist between monomer units. Ester bonds can be formed by the general formula [OR-OC(O)-R′-C(O)]. n This indicates that R and R′ are the same or different alkyl (or aryl) groups and can usually be formed by the polymerization of dicarboxylic acid and diol monomers.

[0057] As used herein, the term "polyamide" refers to a high molecular weight polymer having amide bonds (--CONH--)n present along the molecular chain and includes "nylon" resins, which are well-known polymers with a wide range of uses, including as packaging films. Examples of nylon polymer resins used 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 homopolymers and copolymers such as nylon 4,6 (poly(tetramethylene hexamethylene)), nylon 6 (polycaprolactam), nylon 6,6 (poly(hexamethylene hexamethylene)), nylon 6,9 (poly(hexamethylene azelamide)), nylon 6,10 (poly(hexamethylene decanamide)), nylon 6,12 (poly(hexamethylene dodecanediamide)), nylon 6 / 12 (poly(caprolactam-co-dodecanediamide)), nylon 6,6 / 6 (poly(hexamethylene hexamethylene-co-caprolactam)), nylon 66 / 610 (e.g., manufactured by condensation of a mixture of nylon 66 salt and nylon 610 salt), nylon 6 / 69 resin (e.g., manufactured by condensation of ε-caprolactam, hexamethylenediamine and azelaic acid), nylon 11 (polyundecanolactam), nylon 12 (polylauryl lactam), 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 chosen as materials to improve the temperature resistance, abrasion resistance, puncture strength, and / or barrier properties of films. The properties of polyamide-containing films can be modified by selecting a variety of variables, including copolymer selection and conversion methods (e.g., co-extrusion, orientation, lamination, and coating).

[0058] As used herein, “polyurethane” generally refers to a polymer having organic units linked by urethane bonds (-NH-(C=O)-O-).

[0059] As used in this article, "polylactic acid" refers to a substance made from lactic acid and possessing the properties [–C(CH3)HC(=O)O–]. n Polymers with a main chain.

[0060] As used throughout this application, the term "ethylene alcohol copolymer" refers to a film-forming copolymer of ethylene alcohol (CH2CHOH). Examples include, but are not limited to, ethylene-ethylene alcohol copolymer (EVOH), butanediol-ethylene alcohol copolymer (BVOH), and polyvinyl alcohol (PVOH).

[0061] As used throughout this application, the terms "ethylene-vinyl alcohol copolymer," "EVOH copolymer," or "EVOH" refer to a copolymer composed of repeating units of ethylene and vinyl alcohol. An ethylene-vinyl alcohol copolymer can be represented by the following general formula: [(CH2-CH2)] n -(CH2-CH(OH))] n Ethylene-vinyl alcohol copolymers may include saponified or hydrolyzed ethylene-vinyl acetate copolymers. EVOH refers to an ethylene alcohol copolymer having ethylene comonomers and prepared by, for example, the hydrolysis of a vinyl acetate copolymer or by a chemical reaction with ethylene alcohol. Ethylene-vinyl alcohol copolymers may contain 28 mol% (or less) to 48 mol% (or more) of ethylene.

[0062] As used herein, the term "layer" refers to a building block of a membrane, which 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, may contain metallic materials, and may have additives. Layers can be continuous with the membrane or can be discontinuous or patterned. A layer has a negligible thickness (z-direction) compared to its length and width (xy-direction) and is therefore defined as having two principal surfaces whose area is defined by the length and width of the layer. An outer layer is a layer that connects to another layer at only one principal surface. In other words, one principal surface of the outer layer is exposed. An inner layer is a layer that connects to another layer at two principal surfaces. In other words, the inner layer lies between two other layers. A layer may have sublayers.

[0063] Similarly, as used herein, the term "membrane" refers to a web composed of layers and / or membranes, all of which are directly adjacent to and connected to each other. A membrane can be described as having a thickness that is insignificant compared to its length and width. A membrane has two main surfaces whose areas are defined by its length and width.

[0064] As used herein, the term "outer" describes a membrane or layer located on one of the main surfaces of the membrane that includes it. As used herein, the term "inner" describes a membrane or layer located on a surface of the membrane that does not include it. An inner membrane or layer is adjacent to another membrane or layer on both sides.

[0065] As used herein, “waveform structure” refers to the cross-sectional geometry of the surface of the inorganic coating and one or more adjacent polymer buffer layers. Like any wave, a waveform structure has a wavelength that can be measured in the xy direction and an amplitude that can be measured in the z direction.

[0066] The wavelength of a waveform structure can be determined using top-view microscopy techniques, including but not limited to optical microscopy, laser scanning microscopy, electron microscopy, or atomic force microscopy. The microscope's resolution needs to be sufficient to identify features on the waveform, such as peaks and troughs. Figure 11 The diagram illustrates an example of a representative top-view microscopy method. As shown in the view, waveforms exhibit various patterns and are organized into wave domains or regular, ordered portions of the waveform. Wave domains intersect at corners or edges, forming irregular folds or intersections. Waveform measurements can be performed within these wave domains, instances of which are indicated by superimposed ellipses. Variations in waveform measurements may occur at intersections, instances of which are indicated by superimposed circles, as colliding waveforms will interfere with the regular pattern. The region including the intersections of waveforms is not used for waveform measurements.

[0067] Wavelength is the distance between peaks or troughs in the distortion-free region (i.e., the wave domain) of a waveform. The average wavelength is calculated by averaging at least five individual wavelength measurements.

[0068] Other techniques for determining wavelength are possible. For example, wavelength can be measured using a cross-sectional view of a waveform structure. Another option is to measure wavelength in an optical device that uses the waveform as a grating. Wavelength can be determined using the spectrum obtained by irradiating the film.

[0069] The amplitude of waveform structures (i.e., the distance from trough to crest) can be evaluated on a membrane using a z-axis information-sensitive microscope. For example, the microscope could be a laser scanning microscope or an atomic force microscope. In some implementations, the resolution in the z-axis can be as small as tens of nanometers.

[0070] In some embodiments of the membrane, the amplitude can be determined under a microscope at appropriate resolution and contrast on a cut cross-section (i.e., sliced, embedded in epoxy resin and polished, or otherwise). Since the shrinkage in laminates containing many layers is generally less than that in membranes containing only a polyolefin substrate, a polymer buffer layer, and an inorganic coating, the amplitude in the membrane may be lower.

[0071] As used in this paper, the “average amplitude” is determined by measuring the amplitude of at least five individual waveforms at one or more locations in the distortion-free region (i.e., the wave domain) using a transmembrane sample and calculating the average of these five measurements.

[0072] As used herein, "barrier," "barrier film," "barrier layer," or "barrier material" refers to providing reduced permeability to gases such as oxygen (i.e., oxygen-containing barrier materials). Barrier materials can provide reduced permeability to moisture (i.e., moisture-containing barrier materials). Barrier properties can be provided by one or more barrier materials or blends of multiple barrier materials. Barrier layers can provide the specific barriers required to preserve the product within the package for an extended shelf life (potentially several months or even more than a year).

[0073] Barriers reduce the inflow of oxygen through the barrier packaging film during the shelf life of the packaged product (i.e., when the packaging is hermetically sealed). The oxygen permeability (OTR) of the barrier packaging film is an indication of the barrier provided and can be measured according to ASTM F1927 using conditions of 1 atmosphere, 23°C, and 50% RH.

[0074] As used herein, “barrier packaging film” or “airtight sealing packaging” or “retort-stabilized packaging” refers to a film or packaging made of a film that maintains a high level of oxygen or moisture barrier without degradation after exposure to heat treatment temperatures, at or above heat treatment temperatures. The packaging can be filled with product, sealed, and kept airtight, thus maintaining excellent barrier properties.

[0075] As used herein, "Young's modulus," "elastic modulus," or simply "modulus" is a measure of a material's ability to change size under tensile or compressive forces, expressed as force per unit area. Materials with a higher Young's modulus are relatively hard, while materials with a lower Young's modulus are relatively soft and flexible (i.e., elastic). Young's modulus can be calculated from a force-displacement dataset derived from a nanoindentation testing procedure.

[0076] As used herein, “free shrinkage” refers to the unconstrained linear shrinkage of a film or layer due to exposure to elevated temperatures. The shrinkage is irreversible and relatively rapid (i.e., noticeable within seconds or minutes). Free shrinkage is expressed as a percentage of the original size (i.e., 100 × (size before shrinkage - size after shrinkage) / (size before shrinkage)). Free shrinkage can be measured using ASTM D2732. Alternatively, free shrinkage can be measured using the test method described in ASTM D2732, modified to use hot air as the heating source instead of a hot fluid bath. If the hot air method is used, the unconstrained sample is placed in an oven set at a specified temperature for a time span of at least 1 minute, allowing sufficient time for the oven interior and the sample to reach thermal equilibrium.

[0077] As used herein, “ASTM E2546-15 Appendix X.4” refers to an instrumented indentation test procedure performed according to a documented standard using a device comprising a silicon tip mounted on a silicon cantilever having a defined tip radius of 30 nm.

[0078] The barrier packaging films described herein can be used as retort or pasteurization packaging films. As used herein, "retort packaging film" or "retort packaging" refers to a film or packaging made of film that can be filled with product, sealed, and remain airtight after exposure to a typical retort sterilization process. Typical retort sterilization is a batch process using temperatures ranging from about 100°C to about 150°C, overpressures up to about 70 psi (483 kPa), and durations from several minutes to several hours. Common retort processes for products packaged in flexible films include steam or water immersion. Food or other products packaged in retort packaging films and retorted can be stored for extended periods under ambient conditions (i.e., shelf-stable) while remaining sterile. Because the retort process degrades the film or packaging made of film, highly specialized flexible packaging films have been designed to withstand the retort process.

[0079] Surprisingly, it has been found that a membrane structure can be developed to incorporate the formation of a wave-like structure within an inorganic coating when the membrane structure is heated. Upon heating, the membrane structure retains the performance characteristics required for these membranes in packaging applications and other similar uses. For example, the layers required for wave formation can also include the necessary adhesion to adjacent layers, possess appropriate flexibility and transparency, and provide durability under environmental conditions other than thermal exposure (i.e., flexure, puncture, humidity, etc.).

[0080] As used herein, the term "adhesive layer" refers to a layer that has the primary function of bonding two adjacent layers together. An adhesive layer may be positioned between two layers of a multilayer film to hold the two layers in place relative to each other and prevent undesirable delamination. Unless otherwise stated, the adhesive layer may have any suitable composition that provides the desired level of adhesion to one or more surfaces in contact with the adhesive layer material.

[0081] As used herein, the term "sealing layer" refers to a layer of film, sheet, etc., relating to a seal that seals the film, sheet, etc., to itself and / or to another layer of the same film, sheet, etc., or another film, sheet, etc. As used herein, the terms "heat-sealed," "heat-sealed," "heat-sealable," etc., refer to a film layer that can be heat-sealed to itself or other thermoplastic film layers, and to the formation of a fusion bond between two polymer surfaces by conventional indirect heating. It should be understood that conventional indirect heating generates sufficient heat on at least one film contact surface to conduct to adjacent film contact surfaces, thereby achieving the formation of an interfacial bonding interface without compromising film integrity.

[0082] As used herein, the term "printed marking layer" refers to a layer or series of sublayers that have been printed onto a film. The layer or sublayers may include a pigment-containing material (i.e., colored ink), a protective layer (i.e., a topcoat), and an ink-absorbing primer. The topcoat protects the printed pigment layer and can improve the appearance of the film surface. Each of one or more printed marking layers may be independent of the other layers of the film, either continuous or independent of the other layers (i.e., patterned). Specifically, a printed marking layer may include one or more continuous sublayers of white pigment printing and one or more patterned sublayers including other colors, thereby producing a visible graphic on the packaging film. Printing of the printed marking layer can be accomplished by any known printing method, including but not limited to flexographic gravure printing, rotary gravure printing, gravure coating, and digital printing methods. Sublayers within a printed marking layer may be applied using the same process or by using different types of processes.

[0083] As mentioned, the printed marking layer may include one or more sublayers containing white pigment printing. Typically, the white pigment in the printing ink comprises titanium dioxide (TiO2) particles. If the TiO2 particles are located near the inorganic oxide coating, they may cause disruption to the formation of the waveform structure. Embodiments of the barrier packaging film may include one or more layers between the inorganic oxide coating and the printed marking layer containing TiO2 particles. Other printed marking layer sublayers (e.g., non-white sublayers, primer sublayers) may exist between the TiO2-containing sublayer and the inorganic oxide coating. An adhesive layer, such as..., may exist between the TiO2-containing layer and the inorganic oxide coating. Figure 1B and 5B The illustrated embodiment. In any embodiment, 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 waveform formation.

[0084] We now turn to the specific details of the implementation scheme for the barrier packaging film structure. Figure 1A A cross-sectional view of a barrier packaging film 10 is shown. The barrier packaging film 10 includes a polyolefin substrate 12, an inorganic coating 13, and a polymer buffer layer 14 positioned between the polyolefin substrate 12 and the inorganic coating 13. The polymer buffer layer 14 is in direct contact with the inorganic coating 13. The polymer buffer layer 14 can be in direct contact with the polyolefin substrate 12, such as... Figure 1A As shown, one or more additional layers may exist between the polymer buffer layer 14 and the polyolefin substrate 12. In some embodiments, the barrier packaging film 10 further includes a polyolefin sealing layer 11, a printed marking layer 16, and an adhesive layer 15. The polyolefin substrate 12 forms the outer layer of the barrier packaging film 10, and the polyolefin sealing layer 11 forms the opposite outer layer of the barrier packaging film 10.

[0085] An embodiment of a barrier packaging film including a printed marking layer directly adjacent to an inorganic coating may include sublayers within the printed marking layer. A primer sublayer may be directly adjacent to the inorganic coating, followed by one or more pigment-containing sublayers. The primer-containing sublayer may be a continuous layer. The primer-containing sublayer may act as a second buffer layer, as will be discussed below.

[0086] In yet another alternative implementation scheme, Figure 1B A cross-sectional view of a similar barrier packaging film 10 is shown. Here, the positions of the printed marking layer 16 and the adhesive layer 15 have been interchanged. Figure 1B The illustrated embodiment shows that a combination of polyolefin substrate 12 / polymer buffer layer 14 / inorganic coating 13 or a polyolefin sealing layer 11 can be printed prior to the lamination step. In another embodiment (not shown), both components can be printed prior to lamination.

[0087] Figure 2 A cross-sectional view illustrating a specific embodiment of the barrier packaging film 20 is shown. Figure 2 In this process, the barrier packaging film 20 includes a polyolefin substrate 22, an inorganic coating 23, and a polymer buffer layer 24 positioned between the polyolefin substrate 22 and the inorganic coating 23. The polymer buffer layer 24 is in direct contact with the inorganic coating 23. The polymer buffer layer 24 can also be in direct contact with the polyolefin substrate 22, such as... Figure 2 As shown, one or more additional layers may exist between the polymer buffer layer 24 and the polyolefin substrate 22. In some embodiments, the barrier packaging film 20 further includes a polyolefin sealing layer 21, a printed marking layer 26, and an adhesive layer 25. The printed marking layer 26 forms the outer layer of the barrier packaging film 20, and the polyolefin sealing layer 21 forms the opposite outer layer of the barrier packaging film 20. In this location, the printed marking layer 26 may include a heat-resistant topcoat layer for the purpose of protecting the pigment layer from scratches and exposure to heat sources. The advantage obtained in this embodiment is that monochrome (unprinted) film laminates can be mass-produced, and then specific graphics can be printed on a small portion of the film for each packaging application. This avoids the generation of large amounts of waste during the packaging film production process.

[0088] Figure 3 A cross-sectional view of another embodiment of the barrier packaging film 30 is illustrated. In this embodiment, the barrier packaging film 30 includes a polyolefin substrate 32, an inorganic coating 33, and a polymer buffer layer 34 positioned between the polyolefin substrate 32 and the inorganic coating 33. The polymer buffer layer 34 is in direct contact with the inorganic coating 33. The polymer buffer layer 34 can be in direct contact with the polyolefin substrate 32, such as... Figure 3As shown, one or more additional layers may exist between the polymer buffer layer 34 and the polyolefin substrate 32. In some embodiments, the barrier packaging film 30 further includes a polyolefin sealing layer 31, an oriented outer layer 37, a printed marking layer 36, and an adhesive layer 35. In some embodiments, the polyolefin sealing layer 31 is part of the polyolefin substrate 32 (i.e., a sublayer of the polyolefin substrate). The oriented outer layer 37 is formed of polyolefin and forms the outer layer of the barrier packaging film 30. The polyolefin sealing layer 31 forms the opposite outer layer of the barrier packaging film 30.

[0089] Depend on Figure 3 An example of the barrier packaging film 30 represented includes BOPP (37) / printed markings (36) / adhesive (35) / SiOx (33) / PU buffer (34) / multilayer MDOPP (32), wherein the MDOPP (32) film contains an outer layer (31) containing a polypropylene material suitable for heat sealing.

[0090] Figure 4 A cross-sectional view of another embodiment of the barrier packaging film 40 is shown. Figure 4 In this process, the barrier packaging film 40 includes a polyolefin substrate 42, an inorganic coating 43, and a polymer buffer layer 44 positioned between the polyolefin substrate 42 and the inorganic coating 43. The polymer buffer layer 44 is in direct contact with the inorganic coating 43. In some embodiments, the polymer buffer layer 44 may be in direct contact with the polyolefin substrate 42, such as... Figure 4 As shown, one or more additional layers may exist between the polymer buffer layer 44 and the polyolefin substrate 42. In some embodiments, the barrier packaging film 40 further includes a polyolefin sealing layer 41, a printed marking 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 sealing layer 41 forms the opposite outer layer of the barrier packaging film 40. In some embodiments, the second polymer buffer layer 48 is in direct contact with the inorganic coating 43, opposite to 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 in terms of 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. This additional buffer layer is important in structures in which both the polyolefin substrate and the polyolefin sealing layer exhibit shrinkage properties at elevated temperatures.

[0091] 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. Free shrinkage of the polyolefin substrate at 95°C or another elevated processing temperature to which the barrier packaging film is exposed results in a reduction in the surface area of ​​the polyolefin substrate. It is believed that due to the reduction in surface area, any layer adjacent to or near the shrinking polyolefin substrate experiences shrinkage forces in the xy direction.

[0092] The free shrinkage of the polyolefin substrate at 95°C can range from 0.5% to 10%, from 0.5% to 8%, from 1% to 10%, or from 1% to 6%. The free shrinkage of the polyolefin substrate can be measured alone on the polyolefin substrate (including any sublayers that may be present). Alternatively, the free shrinkage of the polyolefin substrate can be measured in a combination of the polyolefin substrate and a polymer buffer layer plus any intermediate layer. The free shrinkage of the polyolefin substrate can also be measured when it is attached to an inorganic coating (including a polymer buffer layer and any other intermediate layer).

[0093] The polyolefin substrate comprises any polymer, including but not limited to polyethylene, polypropylene, or blends of these polymers. The polyolefin substrate may include any number of sublayers. Sublayers of the polyolefin substrate may include polymers within the same polymer class (i.e., all layers are various types of polypropylene polymers), or sublayers may be from different polymer classes. The polyolefin substrate may be oriented or non-oriented. The polyolefin substrate may be relatively transparent, translucent, or opaque. The polyolefin substrate may have printed markings deposited on either of its main surfaces.

[0094] The polyolefin substrate can be a film, and this film can be produced by any known process, such as blown film or 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 produced using specific polymers and can be oriented under specific conditions to optimize the film's heat resistance.

[0095] The polyolefin substrate can have a thickness ranging from 6 μm to 100 μm (before shrinkage). In some embodiments, the polyolefin substrate can have a thickness ranging from 10 μm to 50 μm, or from 10 μm to 30 μm.

[0096] The inorganic coating of the barrier packaging film can be a metal or inorganic oxide applied via a vacuum deposition process such as chemical vapor deposition or physical vapor deposition. Alternatively, the inorganic coating can be applied using wet chemical techniques. The inorganic coating is deposited on the surface of the polymer buffer layer. The inorganic coating is directly adjacent to and in direct contact with the polymer buffer layer.

[0097] Inorganic coatings significantly contribute to the reduction of the oxygen barrier (OTR) in barrier packaging films. Inorganic coatings can be transparent oxide coatings such as AlOx (i.e., aluminum oxide) or SiOx (i.e., silicon oxide). Oxide coatings can be produced through a vacuum deposition process.

[0098] Inorganic coatings can include metallic layers such as aluminum or blends of aluminum with another metal. Metallic layers can be produced through a vacuum deposition process.

[0099] Refer again Figure 1A , 1B Inorganic coatings 13, 23, 33, and 43 have thicknesses 13A, 23A, 33A, and 43A measured in the z-direction, respectively. The inorganic coatings 13, 23, 33, and 43 have thicknesses 13A, 23A, 33A, and 43A within the ranges of 0.005 μm to 0.1 μm, 0.005 μm to 0.06 μm, 0.01 μm to 0.1 μm, or 0.01 μm to 0.06 μm. Inorganic coatings with thicknesses greater than these ranges may cause the layer to be unable to flex into a corrugated structure to accommodate changes in surface area without cracking or otherwise failing.

[0100] In some embodiments, the polymer buffer layer of the barrier packaging film is located between the polyolefin substrate and the inorganic coating. In some embodiments, the polymer buffer layer is in direct contact with the inorganic coating. The polymer buffer layer may be in direct contact with the polyolefin substrate. The polymer buffer layer may be a sublayer within a film that also contains a polyolefin substrate. In some embodiments of the barrier packaging film, an intermediate layer may be present between the polymer buffer layer and the polyolefin substrate.

[0101] Non-limiting 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. Similarly, non-limiting embodiments of the polymer buffer layer may be produced by coating, extrusion, co-extrusion, or lamination. The buffer layer may have inherent barrier properties (oxygen or moisture barrier), which can contribute to the overall barrier properties of the barrier packaging film.

[0102] Refer again Figure 1A , 1B Polymer buffer layers 14, 24, 34, and 44 have thicknesses 14A, 24A, 34A, and 44A measured in the z-direction. The polymer buffer layers 14, 24, 34, and 44 have thicknesses 14A, 24A, 34A, and 44A in the ranges of 0.5 μm to 12 μm, 1 μm to 5 μm, or 1 μm to 2.5 μm.

[0103] The ratio of the thickness of the polymer buffer layer of the barrier packaging film to the thickness of the inorganic coating of the barrier packaging film is in the range of 20 to 500 or in the range of 30 to 120. This thickness ratio within this range is one of the factors that allow the formation of a wavy structure in the inorganic coating when the polyolefin substrate shrinks.

[0104] The polymer buffer layer exhibits a Young's modulus ranging from 0.1 MPa to 100 MPa at elevated temperatures such as 95°C. This property of the polymer buffer layer, combined with its location and thickness, as well as other details of the film structure, advantageously allows for the formation of a wave-like structure in the inorganic coating during the shrinkage of the polyolefin substrate, thereby preventing cracking and loss of barrier properties.

[0105] The polyolefin seal layer may contain polyolefin materials. The seal layer may contain polymer formulations designed to lower the heat-sealing initiation temperature to complement the heat resistance of the relative outer layer. Although the seal layer may have a fairly low temperature softening point, it may possess sufficient integrity to withstand the high temperatures of retort sterilization processes and other abuse the packaging may experience during distribution and use.

[0106] In some embodiments, the sealing layer of the barrier packaging film has components that allow for the formation of a heat seal, thereby creating an airtight package. As used herein, the terms "heat-sealed" or "heat-sealed" refer to two or more surfaces bonded together by applying both heat and pressure for a short period of time or by an ultrasonic energy sealing process. Heat sealing and ultrasonic sealing are well-known and commonly used methods for producing packaging and are familiar to those skilled in the art.

[0107] The sealing layer must be on the surface of the barrier packaging film to facilitate its sealing function. During the use of the barrier packaging film in the packaging, the sealing layer can be heat-sealed to itself or another packaging component. During heat sealing, the sealing layer softens at a sealing temperature lower than the temperature resistance of the opposite outer layer of the barrier packaging film, thereby allowing the formation of a heat-sealed bond. It is believed that the sealing layer softens and forms a heat seal under sealing conditions (time, temperature, and pressure) that do not cause excessive shrinkage or damage to the outer surface of the barrier packaging film.

[0108] The goal of barrier packaging films is to contain a significant amount of polyolefins, particularly polypropylene or polyethylene, so that the barrier packaging film is acceptable for recycling processes. Polyolefins have relatively low heat resistance compared to materials traditionally used in packaging films (i.e., polyester, aluminum foil, polyamide). Due to this lower heat resistance, the packaging will be formed using a lower-temperature heat-sealing process to avoid any shrinkage or burn-through. The challenge of the barrier packaging films disclosed herein is incorporating a sealing layer with a low heat seal initiation temperature (HSIT) and high seal strength and toughness to withstand retort or pasteurization treatments, as well as normal distribution and handling (i.e., drop strength and burst strength). In some embodiments, the sealing layer also contains materials approved for contact with food during retort conditions, as specified by government food safety agencies.

[0109] The sealing layer may contain a material with a low heat seal initiation temperature (HSIT). In some embodiments of retort packaging films, the sealing layer contains a polypropylene copolymer with a melt temperature equal to or below 135°C.

[0110] The barrier packaging film may have an overall thickness of about 63.5 μm to about 254 μm, or about 76.2 μm to about 152.4 μm.

[0111] Although the structure of barrier packaging films and any packaging made therefrom contains several different elements (sealing layers, polyolefin substrates, inorganic coatings, cushioning layers, etc.), the overall composition of the film or packaging should have a high level of a single material type (polyolefin or specifically polypropylene or polyethylene) to facilitate recycling. As used herein, the term "overall composition" is used to describe the entire film structure or packaging. Any material, layer, or component connected to each other in any way is part of the overall composition of the article. Barrier packaging films may have a high level of polyolefin-based polymers. Packaging films may have a high level of polypropylene-based polymers. Packaging films may have a high level of polyethylene-based polymers. When an article contains a significant amount of polypropylene-based polymers, the packaging films described herein and any packaging made therefrom can be recycled in a polypropylene recycling process. When an article contains a significant amount of polyethylene-based polymers, the packaging films described herein and any packaging made therefrom can be recycled in a polyethylene recycling process. Mixed polyolefin recycling processes may also accept relatively high levels of polyolefins present in the packaging films described herein and any packaging made therefrom.

[0112] The barrier packaging film described herein may have a total composition containing at least 80% by weight, at least 85% by weight, or at least 90% by weight of a polyolefin-based polymer, thereby facilitating the recyclability of the film and / or the packaging in which the film is used. Materials that are not based on polyolefins are minimized. For example, the inorganic coating of the barrier packaging film is made of a material that is not based on polyolefins and is therefore provided as a layer as thin as possible to properly function as a barrier. The film may also contain other non-polyolefin materials, such as those located in the adhesive layer and the printed marking layer.

[0113] In a specific embodiment of the barrier packaging film, the film has a total composition containing at least 80% by weight, at least 85% by weight, or at least 90% by weight of a polypropylene-based polymer. In another specific embodiment of the barrier packaging film, the film has a total composition containing at least 80% by weight, at least 85% by weight, or at least 90% by weight of a polyethylene-based polymer.

[0114] By using a combination of membrane structure design elements as described herein, more heat-resistant barrier packaging films can be achieved. Due to the high polyolefin content, the films are suitable for recycling in polyolefin-based recycling processes. The films may have low levels (i.e., ≤5% by weight) of materials such as polyester, polyamide, chlorinated polymers, and aluminum foil, or may be substantially free of materials such as polyester, polyamide, chlorinated polymers, and aluminum foil. The films may contain non-polyolefin-based polymers, such as those used in adhesive or ink layers, but the amount of non-polyolefin-based polymers is minimized and typically constitutes less than 10% by weight or less than 5% by weight of the total composition. The films may contain non-polymer materials such as barrier materials, but the amount of non-polymer materials is minimized and typically constitutes less than 10% by weight or less than 5% by weight of the total composition.

[0115] As previously described herein, increased ambient temperature can cause polyolefin substrates to shrink slightly in one or more directions. As temperature rises, the polymer material softens, thereby releasing tension that may have been embedded in the layers during production. This tension release can lead to the movement and rearrangement of polymer chains and ultimately, changes in the dimensions of the layers (increase or decrease). A common result of increased temperature on polyolefin substrates is a slight reduction (i.e., shrinkage) of the substrate in at least one direction parallel to the xy-plane of the layer.

[0116] When the polyolefin substrate shrinks, compressive forces are applied to other layers within the barrier packaging film, with the greatest force applied to adjacent layers. These other layers may also tend to shrink at elevated temperatures, and the free shrinkage of each layer is likely to differ slightly. The greatest difference in free shrinkage is likely to be found when comparing any polymer layer to the inorganic coating of the barrier packaging film. Most inorganic coatings do not experience shrinkage at temperatures where the polyolefin substrate would shrink (e.g., 95°C or some other temperature). Furthermore, inorganic coatings also exhibit very high modulus (high stiffness) at these elevated temperatures.

[0117] Using the defined structure of one or more embodiments of the barrier packaging film described herein, the polyolefin substrate and possibly other layers of the structure will begin to shrink upon exposure to elevated temperatures. In some embodiments, the tightly bonded polymer buffer layer with a low modulus will experience compressive forces in the xy direction at elevated temperatures and readily conforms to this stress. As the surface area of ​​the polyolefin substrate (xy direction) decreases and the 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 is not flexible (i.e., it has a high modulus and high stiffness). Due to the xy-direction compressive forces from the shrinking polyolefin substrate and the low modulus of the underlying (i.e., directly adjacent) polymer buffer layer, the inorganic coating may have a tendency to bend into a wavy pattern, with the amplitude of the wave forming in the z direction. The formation of the wavy structure will preserve the surface area of ​​the inorganic coating, thereby preventing typical cracks that would normally form under shrinkage forces in the absence of a suitable polymer buffer layer.

[0118] Figure 5A The cross-sectional view shown illustrates the barrier packaging film 50, which, along with... Figure 1A The barrier packaging film shown is the same, except that the inorganic coating now presents a wavy form. In other words, Figure 1A The barrier packaging film 10 has been exposed to elevated temperatures, causing shrinkage of the polyolefin substrate. The barrier packaging film 50 includes a polyolefin substrate 52, an inorganic coating 53, and a polymer buffer layer 54 positioned between the polyolefin substrate 52 and the inorganic coating 53. In some embodiments, the polymer buffer layer 54 is in direct contact with the inorganic coating 53. The polymer buffer layer 54 may be in direct contact with the polyolefin substrate 52, such as... Figure 5A As shown, one or more additional layers may be present between the polymer buffer layer 54 and the polyolefin substrate 52. In some embodiments, the barrier packaging film 50 further includes a polyolefin sealing layer 51, a printed marking 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 sealing layer 51 forms the opposite outer layer of the barrier packaging film 50.

[0119] Figure 5B The cross-sectional view shown illustrates the barrier packaging film 50, which, along with... Figure 1B The barrier packaging film shown is the same, except that the inorganic coating now presents a wavy form. In other words, Figure 1B The barrier packaging film 10 has been exposed to elevated temperatures, causing shrinkage of the polyolefin substrate. (The last sentence appears to be incomplete and possibly contains errors.) Figure 5A In contrast, the positions of the printed marking layer 56 and the adhesive layer 55 have been swapped.

[0120] Figure 6 The cross-sectional view shown illustrates the barrier packaging film 60, which, along with... Figure 2 The barrier packaging film shown is the same, except that the inorganic coating now presents a wavy form. In other words, Figure 2 The barrier packaging film 20 has been exposed to elevated temperatures, causing shrinkage of the polyolefin substrate. Figure 6 In this process, the barrier packaging film 60 includes a polyolefin substrate 62, an inorganic coating 63, and a polymer buffer layer 64 positioned between the polyolefin substrate 62 and the inorganic coating 63. In some embodiments, the polymer buffer layer 64 is in direct contact with the inorganic coating 63. The polymer buffer layer 64 may be in direct contact with the polyolefin substrate 62, such as... Figure 6 As shown, one or more additional layers may be present between the polymer buffer layer 64 and the polyolefin substrate 62. In some embodiments, the barrier packaging film 60 further includes a polyolefin sealing layer 61, a printed marking layer 66, and an adhesive layer 65. In some embodiments, the printed marking layer 66 forms the outer layer of the barrier packaging film 60, and the polyolefin sealing layer 61 forms the opposite outer layer of the barrier packaging film 60.

[0121] Figure 7 The cross-sectional view shown illustrates the barrier packaging film 70, which, along with... Figure 3 The barrier packaging film shown is the same, except that the inorganic coating now presents a wavy form. In other words, Figure 3 The barrier packaging film 70 has been exposed to elevated temperatures, causing shrinkage of the polyolefin substrate. In this embodiment, the barrier packaging film 70 includes a polyolefin substrate 72, an inorganic coating 73, and a polymer buffer layer 74 positioned between the polyolefin substrate 72 and the inorganic coating 73. In some embodiments, the polymer buffer layer 74 is in direct contact with the inorganic coating 73. The polymer buffer layer 74 may be in direct contact with the polyolefin substrate 72, such as... Figure 7As shown, one or more additional layers may exist between the polymer buffer layer 74 and the polyolefin substrate 72. In some embodiments, the barrier packaging film 70 further includes a polyolefin sealing layer 71, an oriented outer layer 77, a printed marking layer 76, and an adhesive layer 75. In some embodiments, the polyolefin sealing layer 71 is part of the polyolefin substrate 72 (i.e., a sublayer of the polyolefin substrate). In some embodiments, the oriented outer layer 77 is formed of polyolefin and forms the outer layer of the barrier packaging film 70. In some embodiments, the polyolefin sealing layer 71 forms the opposite outer layer of the barrier packaging film 70.

[0122] Figure 8 The cross-sectional view shown illustrates the barrier packaging film 80, which, along with... Figure 4 The barrier packaging film shown is the same, except that the inorganic coating now presents a wavy form. In other words, Figure 4 The barrier packaging film 40 has been exposed to elevated temperatures, causing shrinkage of the polyolefin substrate. Figure 8 In this process, the barrier packaging film 80 includes a polyolefin substrate 82, an inorganic coating 83, and a polymer buffer layer 84 positioned between the polyolefin substrate 82 and the inorganic coating 83. In some embodiments, the polymer buffer layer 84 is in direct contact with the inorganic coating 83. The polymer buffer layer 84 may be in direct contact with the polyolefin substrate 82, such as... Figure 8 As shown, one or more additional layers may exist between the polymer buffer layer 84 and the polyolefin substrate 82. In some embodiments, the barrier packaging film 80 further includes a polyolefin sealing layer 81, a printed marking 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 sealing layer 81 forms the opposite outer layer of the barrier packaging film 80. In some embodiments, the second polymer buffer layer 88 is in direct contact with the inorganic coating 83 and is opposite to 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 in terms of content, thickness, and physical properties.

[0123] Figure 5A , 5B The waveform structures shown in 6, 7 and 8 are characterized by wavelengths of 53C, 63C, 73C, and 83C and amplitudes of 53B, 63B, 73B, and 83B.

[0124] In some embodiments of the barrier packaging film in which a waveform structure has been formed, the average amplitude of the waveform 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 waveform structure can be in the range of 2 μm to 5 μm. The waveform structure can also be characterized by the ratio of wavelength to average amplitude, which is in the range of 2 to 20 or in the range of 4 to 10.

[0125] In embodiments of barrier packaging films comprising a waveform structure formed in an inorganic coating, the thickness of the polymer buffer layer can range from 1.1 to 20 times the average amplitude of the waveform structure. In some embodiments, the thickness of the polymer buffer layer can range from 1.5 to 5 times the average amplitude of the waveform structure.

[0126] When the barrier packaging film includes a wave-like structure formed in an inorganic coating, 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 of the wave, i.e., between the peak and trough.

[0127] In some implementations, the barrier packaging film may have a thickness of less than or equal to 2 cm before exposure to elevated heat conditions. 3 / m 2 / day, less than or equal to 1cm 3 / m 2 / day, less than or equal to 0.5cm 3 / m 2 / day, or less than or equal to 0.1cm 3 / m 2 The average oxygen permeability (OTR) value per day (measured according to ASTM F1927 under conditions of 1 atmosphere, 23°C, and 50% RH). In some embodiments, the barrier packaging film has a thickness of less than or equal to 2 cm² after exposure to a representative retort sterilization process. 3 / m 2 / day, less than or equal to 1cm 3 / m 2 / day, less than or equal to 0.5cm 3 / m 2 / day, or less than or equal to 0.1cm 3 / m 2 The average OTR value per day. The average OTR value may be close to, at, or below the minimum detection level of the test device. A representative retort sterilization process is completed by cutting a DIN A4 size portion of the packaging film and exposing it to steam sterilization at 128°C and 2.5 bar overpressure for 60 minutes, followed by water spray cooling.

[0128] When barrier packaging films are exposed to temperatures above 95°C, a corrugated structure can be formed. This corrugated structure can be formed in 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 sufficient to raise the film's temperature, thus causing the corrugation to occur. The film can then be used in packaging applications or for another purpose. Alternatively, the barrier packaging film can be exposed to elevated temperatures during or after forming the material into packaging, filling the product, and sealing it hermetically. This elevated temperature can be part of a retort process or another type of pasteurization.

[0129] Barrier packaging films can be formed into packages with or without other packaging components. For example, barrier packaging film 210 can be formed into a flexible stand-up pouch 200, such as... Figure 10 As shown in the diagram. In another embodiment of the hermetic sealed packaging 100, the barrier packaging film 110 may be a lid material that seals to a thermoformed tray or cup, such as... Figure 9 As shown in the image.

[0130] The barrier packaging film disclosed herein maintains excellent barrier properties and visual appearance even after the film has been formed into packaging, filled, airtight sealed and subjected to a cooking sterilization process.

[0131] This disclosure will now be described with reference to the following embodiments.

[0132] Examples and Data Several membrane structures are generated as outlined in Table 1 below.

[0133] Table 1: Membrane structures of examples and comparative examples

[0134] The membrane structure of Example 1 was prepared as follows: an aqueous polyurethane (PU) dispersion was applied to the surface of an 18 μm biaxially oriented polypropylene membrane to obtain a 1.7 μm coating after drying the dispersion. A silicon oxide coating (SiOx) was then applied to the surface of the PU coating by vapor deposition. A 60 μm polypropylene sealing layer was then laminated onto the silicon oxide coating by adhesive bonding.

[0135] The membrane structure of Example 2 was prepared as follows: an aqueous polyurethane (PU) dispersion was applied to the surface of an 18 μm biaxially oriented polypropylene membrane to obtain a 1.7 μm coating after drying the dispersion. An aluminum coating was then applied to the surface of the PU coating by vapor deposition. A 60 μm polypropylene sealing layer was then laminated onto the aluminum coating by adhesive bonding.

[0136] The membrane structures of Examples 3 and 4 were prepared as follows: First, a silicon oxide coating was deposited on the heat-sealable surface of a 19 μm heat-sealable biaxially oriented polypropylene (BOPP with HS). The heat-sealable layer of the BOPP membrane was approximately 0.7 μm thick and was a suitable material for a buffer layer. Next, a 60 μm polypropylene sealing layer was laminated onto the silicon oxide coating in an adhesive manner.

[0137] The membrane structure of Example 5 was prepared as follows: An aqueous polyurethane (PU) dispersion was applied to the surface of an 18 μm biaxially oriented polypropylene membrane to obtain a 1.7 μm coating after drying the dispersion. A silicon oxide coating (SiOx) was then applied to the surface of the PU coating by vapor deposition. Next, another layer of aqueous PU dispersion was applied to the surface of the silicon oxide coating. A 60 μm polypropylene sealing layer was then bonded to the exposed PU buffer coating.

[0138] The membrane structure of Example 6 was prepared as follows: an aqueous polyurethane (PU) dispersion was applied to the surface of a 25 μm thermally stable biaxially oriented polypropylene membrane to obtain a 1.7 μm coating after drying the dispersion. A silicon oxide coating (SiOx) was then applied to the surface of the PU coating by vapor deposition. A 60 μm polypropylene sealing layer was then laminated onto the silicon oxide coating by adhesive bonding.

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

[0140] Table 2: Free shrinkage of polyolefin substrate layer and Young's modulus of polymer buffer layer at elevated temperatures

[0141] The Young's modulus data shown in Table 3 were collected using atomic force microscopy (AFM) on a Park Systems NX10 AFM in PinPoint™ mode. 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 heated stage. The stage was heated to a suitable test temperature. Force spectroscopy measurements were performed using a silicon tip (SD-R30-FM, available from NanoAndMore GmbH) with a defined tip radius of 30 nm, mounted on a silicon cantilever. The Young's modulus was calculated from the resulting force-displacement curves.

[0142] For each of the embodiment and comparative example structures listed in Table 1, Table 3 contains the layer thickness ratio of the polymer buffer layer to the inorganic coating.

[0143] Table 3: Ratio of polymer buffer layer thickness to inorganic coating thickness

[0144] Table 4 summarizes the waveform formation of the structures in the examples and comparative examples. The structures were heated to a temperature above 95°C and the waveforms were subsequently examined.

[0145] Table 4: Waveform Formation in Examples and Comparative Examples

[0146] Figure 12A , 12B Several top-view micrographs of membrane structures are shown in 12C and 12C, respectively. Figure 12A The membrane shown has a structure of 18 μm BOPP / 1.7 μm PU / 0.04 μm SiOx. Figure 12B The membrane shown has a structure of 18 μm BOPP / 1.7 μm PU / 0.05 μm SiOx. Figure 12C The membrane shown has a structure of 60 μm PP / 3.5 μm adh / 18 μm BOPP / 1.7 μm PU / 0.04 μm SiOx. Figure 12B The polyurethane dispersion used in the structure shown has a very high Young's modulus (over 900 MPa) at 95°C and therefore does not meet the necessary conditions for waveform formation. It should be noted that... Figure 12A , 12B The three photomicrographs illustrated in Figure 12C were not taken at the same magnification and do not show relative waveform characteristics. Instead, these photomicrographs show clear waveform formation of various patterns. Figure 12A and 12C ) and instances of no waveform formation, including clear cracks in inorganic coatings ( Figure 12B ).

[0147] The data in Tables 5a and 5b clearly demonstrate the impact of waveform formation on the barrier performance of the membrane structure. Membranes designed to allow waveform formation during heating and shrinkage exhibit significantly less oxygen barrier loss (smaller OTR increase).

[0148] Table 5a: Average oxygen permeability data for the structures of the examples and comparative examples

[0149] OTR is measured in cm. 3 / (m 2 24h (bar), measured using 23°C and 50% rh according to ASTM 3985-2005.

[0150] Table 5b: Moisture permeability data of the structures in the examples and comparative examples

[0151] WVTR is measured in g / (m³). 2 24h (bar), measured using 38℃ and 90% rh according to ASTM F 1249-90.

[0152] Implementation Plan Implementation Scheme 1: A barrier packaging film comprising: a polyolefin substrate having free shrinkage in the range of 0.5% to 10% in at least one of the longitudinal and transverse directions at 95°C according to ASTM D2732; an inorganic coating with a thickness in the range of 0.005 μm to 0.1 μm; a polymeric buffer layer positioned between the polyolefin substrate and the inorganic coating and in direct contact with each of the polyolefin substrate and the inorganic coating, the polymeric buffer layer having a thickness in the range of 0.5 μm to 12 μm; and a polyolefin sealing layer wherein there is a ratio of the thickness of the polymeric buffer layer to the thickness of the inorganic coating in the range of 20 to 500, and wherein the polymeric buffer layer has a Young's modulus in the range of 0.1 MPa to 100 MPa, calculated from measurements collected at 95°C according to Appendix X.4 of ASTM E2546-15.

[0153] Implementation Scheme 2: The barrier packaging film according to Implementation Scheme 1 further includes an adhesive layer, wherein: the polyolefin substrate is the first outer layer, the polyolefin sealing layer is the second outer layer, and the adhesive layer is located between the polyolefin sealing layer and the inorganic coating.

[0154] Implementation Scheme 3: The barrier packaging film according to Implementation Scheme 2 further includes a printed marking layer located between the polyolefin sealing layer and the inorganic coating.

[0155] Implementation Scheme 4: The barrier packaging film according to Implementation Scheme 1 further includes a printed marking layer and an adhesive layer, wherein: the printed marking layer is a first outer layer, the polyolefin sealing layer is a second outer layer, and the adhesive layer is located between the polyolefin sealing layer and the inorganic coating.

[0156] Implementation Scheme 5: A barrier packaging film according to any of the foregoing implementation schemes, wherein the polyolefin substrate is an oriented polypropylene film and the polyolefin sealing layer is a polypropylene sealing layer.

[0157] Implementation Scheme 6: The barrier packaging film according to Implementation Scheme 5, wherein the oriented polypropylene film comprises homopolymer polypropylene.

[0158] Implementation Scheme 7: A barrier packaging film according to one of Implementation Schemes 1 to 4, wherein the polyolefin substrate is an oriented polyethylene film and the polyolefin sealing layer is a polyethylene sealing layer.

[0159] Implementation Scheme 8: The barrier packaging film according to Implementation Scheme 1 further includes an oriented polyolefin outer layer and an adhesive layer, wherein: the polyolefin sealing layer is a sublayer of the polyolefin substrate, and the adhesive layer is located between the oriented polyolefin outer layer and the inorganic coating.

[0160] Implementation Scheme 9: The barrier packaging film according to Implementation Scheme 8 further includes a printed marking layer located between the oriented polyolefin outer layer and the inorganic coating.

[0161] Implementation Scheme 10: A barrier packaging film according to any of the foregoing implementation schemes, wherein the barrier packaging film has a total composition comprising more than or equal to 80% by weight of polyolefin.

[0162] Implementation Scheme 11: A barrier packaging film according to any of the foregoing implementation schemes, wherein the polyolefin substrate has a thickness in the range of 10 micrometers to 100 micrometers.

[0163] Implementation Scheme 12: A barrier packaging film according to any of the foregoing implementation schemes, wherein the polymer buffer layer has a thickness in the range of 1µm to 5µm.

[0164] Implementation Scheme 13: A barrier packaging film according to any of the foregoing implementation schemes, wherein the inorganic coating comprises a metal layer or an oxide coating and the thickness of the inorganic coating is in the range of 0.005 μm to 0.06 μm.

[0165] Implementation Scheme 14: A barrier packaging film according to any of the foregoing implementation schemes, wherein the ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating is in the range of 30 to 120.

[0166] Implementation Scheme 15: A barrier packaging film according to any of the foregoing implementation schemes, wherein the polymer substrate has a free shrinkage in the range of 1% to 6% at 95°C according to ASTM D2732.

[0167] Implementation Scheme 16: A barrier packaging film according to any of the foregoing implementation schemes, wherein the polymer buffer layer comprises a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

[0168] Implementation Scheme 17: The barrier packaging film according to any of the foregoing implementation schemes further includes a second polymer buffer layer in direct contact with the inorganic coating.

[0169] Implementation Scheme 18: A barrier packaging film comprising: a polyolefin substrate; an inorganic coating; a polymer buffer layer positioned between the polyolefin substrate and the inorganic coating, the polymer buffer layer being in direct contact with the inorganic coating; and a polyolefin sealing layer, wherein the inorganic coating comprises a waveform 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 has a thickness in the range of 1.1 to 20 times the average amplitude of the waveform structure.

[0170] Implementation Scheme 19: The barrier packaging film according to Implementation Scheme 18 further includes an adhesive layer, wherein: the polyolefin substrate is the first outer layer, the polyolefin sealing layer is the second outer layer, and the adhesive layer is located between the polyolefin sealing layer and the inorganic coating.

[0171] Implementation Scheme 20: The barrier packaging film according to Implementation Scheme 19 further includes a printed marking layer located between the polyolefin sealing layer and the inorganic coating.

[0172] Implementation Scheme 21: The barrier packaging film according to Implementation Scheme 18 further includes a printed marking layer and an adhesive layer, wherein: the printed marking layer is a first outer layer, the polyolefin sealing layer is a second outer layer, and the adhesive layer is located between the polyolefin sealing layer and the inorganic coating.

[0173] Implementation Scheme 22: A barrier packaging film according to any one of Implementation Schemes 18 to 21, wherein the polyolefin substrate is an oriented polypropylene film and the polyolefin sealing layer is a polypropylene sealing layer.

[0174] Implementation Scheme 23: The barrier packaging film according to Implementation Scheme 22, wherein the oriented polypropylene film comprises homopolymer polypropylene.

[0175] Implementation Scheme 24: A barrier packaging film according to any one of Implementation Schemes 18 to 21, wherein the polyolefin substrate is an oriented polyethylene film and the polyolefin sealing layer is a polyethylene sealing layer.

[0176] Implementation Scheme 25: The barrier packaging film according to Implementation Scheme 18 further includes an oriented polyolefin outer layer and an adhesive layer, wherein: the polyolefin sealing layer is a sublayer of the polyolefin substrate, and the adhesive layer is located between the polyolefin outer layer and the inorganic coating.

[0177] Implementation Scheme 26: The barrier packaging film according to Implementation Scheme 25 further includes a printed marking layer located between the polyolefin outer layer and the inorganic coating.

[0178] Implementation Scheme 27: A barrier packaging film according to any one of Implementation Schemes 18 to 26, wherein the barrier packaging film has a total composition comprising greater than or equal to 80% by weight of polyolefin.

[0179] Implementation Scheme 28: A barrier packaging film according to any one of Implementation Schemes 18 to 27, wherein the polyolefin substrate has a thickness in the range of 10 micrometers to 100 micrometers.

[0180] Implementation Scheme 29: A barrier packaging film according to any one of Implementation Schemes 18 to 28, wherein the polymer buffer layer has a thickness in the range of 1µm to 5µm.

[0181] Implementation Scheme 30: A barrier packaging film according to any one of Implementation Schemes 18 to 29, wherein the inorganic coating comprises a metal layer or an oxide coating and the thickness of the inorganic coating is in the range of 0.005 μm to 0.06 μm.

[0182] Implementation Scheme 31: A barrier packaging film according to any one of Implementation Schemes 18 to 30, wherein the ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating is in the range of 30 to 120.

[0183] Implementation Scheme 32: A barrier packaging film according to any one of Implementation Schemes 18 to 31, wherein the waveform structure of the inorganic layer is characterized by a ratio of wavelength to average amplitude, said ratio being in the range of 2 to 20.

[0184] Implementation Scheme 33: A barrier packaging film according to any one of Implementation Schemes 18 to 32, wherein the polymer buffer layer comprises a vinyl alcohol copolymer, a polypropylene-based polymer, a polyurethane-based polymer, or polylactic acid.

[0185] Implementation Scheme 34: The barrier packaging film according to any one of Implementation Schemes 18 to 33 further includes a second polymer buffer layer in direct contact with the inorganic coating.

[0186] Implementation Scheme 35: An airtight sealed package comprising a barrier packaging film according to any one of Implementation Schemes 1 to 34.

[0187] Implementation Scheme 36: A barrier packaging film according to any of the foregoing barrier packaging film implementation schemes, comprising a printed marking layer and an inorganic coating comprising a waveform structure, wherein the printed marking layer comprises a sublayer containing TiO2 particles, and wherein there is at least one layer located between the sublayer containing TiO2 particles and the inorganic coating, and the at least one layer located between the sublayer containing TiO2 particles and the inorganic coating has a combined thickness greater than or equal to the average amplitude of the waveform formation.

Claims

1. A barrier packaging film, the barrier packaging film comprising: A polyolefin substrate, wherein the polyolefin substrate, according to ASTM D2732, has free shrinkage in at least one of the longitudinal and transverse directions at 95°C in the range of 0.5% to 10%. An inorganic coating having a thickness in the range of 0.005 micrometers to 0.1 micrometers. A polymer buffer layer is positioned between the polyolefin substrate and the inorganic coating and in direct contact with each of the polyolefin substrate and the inorganic coating, the polymer buffer layer having a thickness in the range of 0.5 micrometers to 12 micrometers. Polyolefin sealing layer, The ratio of the thickness of the polymer buffer layer to the thickness of the inorganic coating exists, and this ratio is in the range of 20 to 500; and The polymer buffer layer described herein has a Young's modulus in the range of 0.1 MPa to 100 MPa, calculated from measurements collected at 95°C according to Appendix X.4 of ASTM E2546-15.

2. The barrier packaging film according to claim 1, wherein the barrier packaging film further comprises an adhesive layer, wherein: The polyolefin substrate is the first outer layer. The polyolefin sealing layer is the second outer layer, and The adhesive layer is located between the polyolefin sealing layer and the inorganic coating.

3. The barrier packaging film according to claim 2, wherein the barrier packaging film further comprises a printed marking layer located between the polyolefin sealing layer and the inorganic coating.

4. The barrier packaging film according to claim 1, wherein the barrier packaging film further comprises a printed marking layer and an adhesive layer, wherein: The printed marking layer is the first outer layer. The polyolefin sealing layer is the second outer layer, and The adhesive layer is located between the polyolefin sealing layer and the inorganic coating.

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

6. The barrier packaging film of claim 5, wherein the oriented polypropylene film comprises homopolymer polypropylene.

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

8. The barrier packaging film according to claim 1, wherein the barrier packaging film further comprises an oriented polyolefin outer layer and an adhesive layer, wherein: The polyolefin sealing layer is a sublayer of the polyolefin substrate, and The adhesive layer is located between the oriented polyolefin outer layer and the inorganic coating.

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

10. The barrier packaging film of claim 1, wherein the barrier packaging film has a total composition comprising more than or equal to 80% by weight of polyolefin.

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

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

13. The barrier packaging film of claim 1, wherein the inorganic coating comprises a metal layer or an oxide coating and the thickness of the inorganic coating 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 is in the range of 30 to 120.

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

16. The barrier packaging film of 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, wherein the barrier packaging film further comprises a second polymer buffer layer in direct contact with the inorganic coating.

18. An airtight sealed package, the airtight sealed package comprising the barrier packaging film according to claim 1.

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