Recyclable membranes and packaging

Abstract

The recyclable film comprises a base film and a sealant. The base film has at least one layer containing a polar polymer and at least one layer containing a polar polymer compatibilizer. Furthermore, the base film is oriented and annealed so that it exhibits less than 10% free shrinkage in both the longitudinal and transverse directions when exposed to heat at 90°C. This film offers advantages over existing recyclable films in terms of efficient film manufacturing, high-quality packaging production, and superior packaging performance.

Description

[0001] This application is a divisional application of Chinese patent application No. 201880083296.4, filed on September 27, 2018, entitled "Recyclable Film and Packaging". Technical Field

[0002] This application relates to films that can be easily recycled. More specifically, a high-performance packaging film that can be recycled in a polyethylene recycling stream is disclosed. Background Technology

[0003] Today, many products, such as consumer goods, food, beverages, pharmaceuticals, industrial chemicals, cleaning agents, cosmetics, and other sensitive items, are packaged in high-performance packaging. This type of packaging offers advantages such as high barrier properties and hermetically sealed openings to help protect and extend the shelf life of the packaged product. Packaging may also include features for consumer usability, such as openable or reclosable features. The materials used to manufacture these packages must withstand the packaging formation process, the filling conditions, and environmental stresses from storage, transportation, and distribution. These requirements are often met through multi-layered packaging that incorporates several different high-performance materials.

[0004] In many cases, high-performance packaging designs incorporate outer layers such as OPET (biaxially oriented polyethylene terephthalate) or BON (biaxially oriented nylon), which offer high stiffness, dimensional stability, and heat resistance. High-performance packaging may also include barrier materials such as aluminum foil, PVdC (polyvinylidene chloride), or EVOH (ethylene vinyl alcohol copolymer). These materials are added to the structure, which also includes polymers specifically designed for sealing, polymers designed to bond the structures together, printing inks, and adhesives, to name just a few. This combination of various materials results in films that are difficult to recycle in available recycling streams. As a result, these packaging films are typically considered "waste" after the packaging is emptied.

[0005] All types of polyethylene structures have been developed for several packaging applications to facilitate recyclability. Processing techniques such as orientation have been added to the functionality of these materials to improve technical performance. However, the performance of these films and packaging continues to suffer. Typically, the packaging has a poor appearance due to a lack of heat resistance and low durability. These types of structures are also inefficient in film conversion, thus driving higher manufacturing costs.

[0006] In some cases, compatibilizers are added to the various layers of the packaging film to facilitate the incorporation of multiple materials into a single material recycling stream. Membrane structures continue to lack properties that match the non-recyclable, high-performance packaging materials currently on the market. Improvements are needed to achieve high-performance packaging film materials that 1) can be efficiently converted, 2) have a cost comparable to current films, 3) can be used on existing packaging equipment, 4) have an acceptable appearance, and 5) can be efficiently recycled into the polyethylene recycling stream. Summary of the Invention

[0007] High-performance flexible packaging design delivers speed, performance, and cost-effectiveness in both the manufacturing of packaging materials and the production of finished packaging. High-performance packaging also provides internal product protection while maintaining an impressive appearance. Typically, high-performance packaging materials are designed with a combination of materials to achieve these requirements. Unfortunately, such a combination of materials often makes it difficult or impossible to recycle the packaging materials into standard reprocessing or recycling flows. This paper describes a recyclable film with properties that enable its use in high-performance packaging applications without the drawbacks often encountered by currently available recyclable films.

[0008] The recyclable membrane may have a base film having a) a first polar layer containing a polar polymer, and b) a compatibilizer layer containing a polar polymer compatibilizer. The recyclable membrane also has a sealant, and optionally printed markings located between the base film and the sealant. The base film of the recyclable membrane is oriented and annealed such that, when tested according to ASTM D2732 using a bath temperature of 90°C, the base film has a free shrinkage value of less than 10% in both the longitudinal and transverse directions.

[0009] In some cases, the polar polymer of the base membrane is a polyamide or a ethylene vinyl alcohol copolymer. The first polar layer can be the outer layer of the base membrane. Alternatively, the first polar layer can be the outer layer of a recyclable membrane.

[0010] Some embodiments of recyclable membranes have a base membrane that, when tested according to ASTM D2732 using a bath temperature of 90°C, exhibits less than 5% free shrinkage in both the longitudinal and transverse directions. The sealant for the recyclable membrane may be a membrane exhibiting less than 1% free shrinkage in both the longitudinal and transverse directions.

[0011] In some embodiments of the recyclable membrane, the base membrane has a) a first polar layer containing a first polar polymer, b) a second polar layer containing a second polar polymer, and c) a compatibilizer layer located between the first and second polar layers, the compatibilizer layer containing a polar polymer compatibilizer. The recyclable membrane also has a sealant and may have printed markings between the base membrane and the sealant.

[0012] In some recyclable membranes, the base film is oriented and annealed such that, as tested according to ASTM D2732 using a bath temperature of 90°C, the base film exhibits a free shrinkage value of less than 10% in both the longitudinal and transverse directions. The base film can be oriented such that the longitudinal elongation at break is less than 100%.

[0013] In some specific embodiments, the recyclable membrane has a base membrane having a) a first outer layer containing polyamide, b) a compatibilizer layer, c) a first adhesive layer located between the first outer layer and the compatibilizer layer, d) a second outer layer containing polyamide, and e) a second adhesive layer located between the compatibilizer layer and the second outer layer. The compatibilizer may contain low molecular weight anhydride or carboxylic acid-functionalized polyethylene and polyethylene, polyethylene copolymers, or blends thereof. The polyethylene in the compatibilizer layer may be LLDPE. The recyclable membrane may further have a sealant.

[0014] The base film of the recyclable membrane can be oriented and annealed so that when tested with a bath temperature of 90°C according to ASTM D2732, the base film has a free shrinkage value of less than 10% in both the longitudinal and transverse directions.

[0015] Some recyclable membrane embodiments further include a barrier material between the base membrane and the sealant. Some recyclable membrane embodiments further include a second sealant such that the base membrane is located between the sealants.

[0016] This document also discloses packaging using the recyclable film described herein, as well as optionally attached packaging components. The recyclable film can be heat-sealed to itself or to an attached packaging component, and the heat-sealing strength is between 200 g / in and 2,500 g / in when tested according to ASTM F88. In some embodiments of the packaging, the recyclable film is configured to be separable from any other packaging components that may be present. In some embodiments, the packaging is configured to be opened to completely remove the product. Attached Figure Description

[0017] This disclosure can be more fully understood by considering the following detailed description of various embodiments of the disclosure in conjunction with the accompanying drawings, in which:

[0018] Figure 1 This is a cross-sectional view of a first embodiment of a base membrane for a recyclable membrane;

[0019] Figure 2 This is a cross-sectional view of a second embodiment of a base membrane used in a recyclable membrane;

[0020] Figure 3 This is a cross-sectional view of a third embodiment of a base membrane for a recyclable membrane;

[0021] Figure 4 This is a cross-sectional view of a first embodiment of the recyclable membrane;

[0022] Figure 5 This is a cross-sectional view of a second embodiment of the recyclable membrane;

[0023] Figure 6 This is a cross-sectional view of a third embodiment of the recyclable membrane; and

[0024] Figure 7a and 7b This is a schematic diagram of an embodiment of packaging that uses a recyclable film as a lid.

[0025] The accompanying drawings illustrate some, but not all, embodiments. The elements depicted in the drawings are illustrative and are not necessarily drawn to scale, and throughout the drawings, the same (or similar) reference numerals denote the same (or similar) features. Detailed Implementation

[0026] High-performance flexible packaging design delivers speed, performance, and cost-effectiveness in both the manufacturing of packaging materials and the production of finished packaging. High-performance packaging also provides internal product protection while maintaining an impressive appearance. Typically, high-performance packaging materials are designed using a combination of materials to achieve these requirements. Unfortunately, this combination of materials often makes the packaging materials difficult to recycle into standard reprocessing or recycling flows.

[0027] In recent years, recycling has been considered in the development of packaging materials. However, these materials often fail to meet the standard requirements of providing product protection, a good appearance, and low cost. The recyclable film described herein uses an oriented and annealed film combining polar polymers and compatibilizers as a base film, combined with a sealant, to design a high-performance packaging film that meets both recycling and performance standards. The packaging described herein is made from a recyclable film designed to have high barrier properties, excellent appearance (transparency), good heat resistance (low shrinkage), high-quality graphics, and good durability. The recyclable film described herein has superior performance compared to recyclable films currently available on the market.

[0028] Recyclable films, and packaging and / or containers comprising such films, preferably possess sealing strength, thermal stability, and heat resistance properties, allowing them to withstand heat-sealing conditions without loss of desired functionality and visual characteristics. Compared to other recyclable films, recyclable films containing a base film with polar polymers that has been oriented and annealed exhibit improved properties in terms of heat resistance, appearance, and overall performance.

[0029] The recyclable membranes described herein utilize a base membrane having a combination of various layers (including, but not limited to, polar layers and compatibilizer layers). The base membrane is then oriented and annealed. The materials in the base membrane and the processing techniques used to manufacture it are combined to produce a cost-effective and high-performance membrane with good heat resistance, low shrinkage, and dimensional stability.

[0030] The base film contains at least one polar layer comprising a polar polymer. As used herein, the term "layer" refers to a structural unit of the film, 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 may be continuous with the film or may be discontinuous or patterned. As used herein, the term "polar polymer" is used to refer to a polymer formed from at least one monomer containing at least one heteroatom such as oxygen (O), nitrogen (N), phosphorus (P), or sulfur (S). A non-limiting example of a polar polymer typically used in packaging applications is a copolymer of polyamide and ethylene vinyl alcohol. The polar layer may contain more than one polar polymer. In addition to the polar polymer, the polar layer may also contain other materials, such as other polymers or additives, such as slip agents or anti-caking agents. Preferably, the polar layer is made of at least 50% polar polymer, or more preferably greater than 70%, greater than 80%, greater than 90%, or greater than 95% polar polymer.

[0031] In some embodiments, the polar polymer in the polar layer may be a polyamide. The term "polyamide" refers to a polymer having amide bonds (--CONH--) along its molecular chain. n The term refers to high molecular weight polymers, including "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(hexamethylene adipamide)), nylon 6 (polycaprolactam), nylon 6,6 (poly(hexamethylene adipamide)), nylon 6,9 (poly(hexamethylene azelaate)), nylon 6,10 (poly(hexamethylene sebacate)), nylon 6,12 (poly(hexamethylene dodecanoate)), nylon 6 / 12 (poly(caprolactam-co-dodecanoate)), nylon 6,6 / 6 (poly(hexamethylene adipamide-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 (polyundecylbridged lactam), nylon 12 (polylaurolactam) and copolymers or mixtures thereof.

[0032] 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).

[0033] In some embodiments, the polar polymer in the polar layer is an ethylene-vinyl alcohol copolymer (EVOH). As used herein, "EVOH" refers to an ethylene-vinyl alcohol copolymer. EVOH is also referred to as a saponified or hydrolyzed ethylene-vinyl acetate copolymer and refers to an ethylene alcohol copolymer having ethylene comonomers. EVOH is prepared by hydrolysis (or saponification) of the ethylene-vinyl acetate copolymer. The degree of hydrolysis is preferably from about 50 mol% to 100 mol%, more preferably from about 85 mol% to 100 mol%, and most preferably at least 97%. It is well known that in order to be an efficient oxygen barrier layer, the hydrolysis-saponification must be almost complete, i.e., to a degree of at least 97%. EVOH is commercially available in resin forms with various percentages of ethylene. Higher ethylene content is expected to promote processability and orientation; however, permeability, especially to oxygen, may become unsuitably high for certain packaging applications that are sensitive to microbial growth in the presence of oxygen. Conversely, lower ethylene content may result in lower gas permeability, but processability and orientation may be more difficult. In some embodiments, the ethylene-vinyl alcohol copolymer comprises from about 27 mol% to 48 mol% ethylene, 27 mol% to 44 mol% ethylene, or even 27 mol% to 29 mol% ethylene. EVOH can be further optimized by blending, special copolymerization, or crosslinking to improve heat resistance or enhance other properties.

[0034] In some embodiments of the recyclable membrane, the base membrane has at least two polar layers. The base membrane may have one, two, or more polar layers. As will be described, the polar layers may be separated by a compatibilizer layer, an adhesive layer, or other layers. Where the base membrane does contain more than one polar layer, the polar layers may have the same composition or different compositions. For example, the base membrane may have one polar layer containing polyamide and a second polar layer containing EVOH. In some embodiments, the base membrane contains two polar layers, each containing polyamide.

[0035] Due to the nature of their chemical composition, many polar polymers typically used in membrane fabrication generally possess different properties compared to nonpolar polymers (i.e., those polymers containing only carbon atoms in their polymer backbone). Polar polymers can offer better oxygen barrier properties, increased stiffness, or increased heat resistance. Furthermore, these properties can be enhanced upon orientation, as will be discussed below.

[0036] It has been unexpectedly discovered that a base film containing two polyamide layers separated by a compatibilizer layer, and longitudinally oriented and annealed, can be used to manufacture packaging films with similar machinability and packaging line efficiency to current packaging structures using BON or OPET. The addition of the compatibilizer layer unexpectedly has no negative impact on the performance of the oriented base film. Advantageously, films using two polyamide layers can be manufactured at a lower cost. Adding a polar polymer compatibilizer to the layer separating the two polyamide layers increases the film's recyclability, yielding significant advantages without compromising its physical properties.

[0037] Advantageously, one or both outer layers of the base membrane may be polar layers. As used herein, the term "outer layer" refers to a membrane layer on either major surface of the membrane, i.e., a layer not between two other layers of the membrane. In some embodiments, both outer layers of the base membrane are polar layers. In some embodiments, both outer layers of the base membrane are polar layers containing polyamide.

[0038] In some embodiments, the outer layer of the base membrane is also the outer layer of the recyclable membrane. In other words, the base membrane is the outer membrane of the recyclable membrane, and no other membrane or layer is applied to the outer layer of the base membrane. In some embodiments, both the outer layer of the base membrane and the outer layer of the recyclable membrane are polar layers. Ideally, both the outer layer of the base membrane and the outer layer of the recyclable membrane are polyamide.

[0039] The polar layer can have any thickness. Typically, the polar layer represents at least 2% of the total base film thickness before orientation.

[0040] The compatibilizer layer of the base film contains a material called a "compatibility agent" that facilitates the incorporation of polar materials into the reprocessing or recycling flow of nonpolar polymers. Compatibilizers typically increase miscibility by providing sites that allow the two materials (polar and nonpolar) to interact, thereby increasing the stability of the dispersed polar materials. The use of compatibilizers in blends of polar and nonpolar materials generally produces more homogeneous blends, avoiding gelation and other problems that cause visual or mechanical property quality issues.

[0041] An example of a compatibilizer that can be used in the compatibilizer layer is Retain 3000, available from Dow Chemical Company. Details of this material and its use as a compatibilizer for polar materials are outlined in patent document WO 16109023 (i.e., '023) by Parkinson et al., which is incorporated herein by reference. However, the films disclosed in '023 do not include any form of oriented film, and therefore lack the dimensional stability and stiffness required for many high-performance packaging applications.

[0042] In some embodiments of the base film, the compatibilizer layer is a blend of polyethylene and low molecular weight anhydride or carboxylic acid-functionalized polyethylene.

[0043] While examples and descriptions of polar polymers herein include polyamides and EVOH, the polar layer of a recyclable membrane is not limited to these materials. While examples and descriptions of compatibilizers include materials that compatibilize polyamides and EVOH into a nonpolar polymer recycle stream, compatibilizers for recyclable membranes are not limited to these materials. Another polar polymer may be used with a functional compatibilizer suitable for that polar polymer, and it remains within the spirit of this disclosure.

[0044] Polyethylene has a basic structure consisting of chains -(CH2-CH2-). n "Polyethylene" is the name of the polymer characterized by its properties. As used herein, the term "polyethylene" includes homopolymers and copolymers of ethylene. Polyethylene homopolymers are generally described as solids with a partially amorphous phase and a partially crystalline phase, having a density between 0.900 and 0.970 g / cm³. The relative crystallinity of polyethylene is known to affect its physical properties. The amorphous phase imparts flexibility and high impact strength, while the crystalline phase imparts a high softening temperature and hardness.

[0045] There are several broad categories of polymers and copolymers collectively referred to as "polyethylene." The inclusion of a specific polymer within one of these categories of polyethylene is often based on the density of the polyethylene, and often additionally on its preparation method, as this method frequently determines the degree of branching, crystallinity, and density. Typically, the nomenclature used is not specific to the compound, but rather refers to a range of compositions. This range often includes homopolymers and copolymers.

[0046] "High-density polyethylene" (HDPE) in this art generally refers to (a) homopolymers with a density between about 0.960 and 0.970 g / cm³ and (b) copolymers of ethylene and α-olefins (typically 1-butene or 1-hexene) having a density between 0.940 and 0.958 g / cm³. HDPE includes polymers prepared using Ziegler or Phillips catalysts and is also said to include high molecular weight polyethylene.

[0047] Medium-density polyethylene (MDPE) typically has a density ranging from 0.928 to 0.940 g / cm³. MDPE includes linear medium-density polyethylene (LMDPE).

[0048] Another group of polyethylene is “low-density polyethylene” (LDPE). LDPE is used to name branched homopolymers with densities between 0.915 and 0.930 g / cm³. LDPE typically contains long branches on the main chain (often called the “backbone”) with alkyl substituents having 2 to 8 carbon atoms.

[0049] Linear low-density polyethylene (LLDPE) is a copolymer of ethylene and α-olefins having a density from 0.915 to 0.940 g / cm³. The α-olefin used is typically 1-butene, 1-hexene, or 1-octene, and a Zieglar-type catalyst is usually employed (although Phillips catalysts are also used to produce LLDPE with densities at the higher end of this range, metallocene complexes and other types of catalysts are also used to produce other well-known LLDPE variants). LLDPE produced using metallocene complexes or catalysts with defined geometries is often referred to as “mLLDPE”. In some specific embodiments, the compatibilizer layer of the base film may have a blend of LLDPE and a compatibilizer.

[0050] Other examples of polyethylene copolymers include, but are not limited to, ethylene vinyl acetate copolymer (EVA), ethylene methyl methacrylate copolymer (EMMA), ethylene-methacrylic acid (EMAA), and ethylene acrylic acid (EAA).

[0051] The base membrane may also have one or more layers for adhesion functions, such as adhesive layers or bonding layers. The terms "adhesive layer," "adhesive," "bonding layer," or "adhesive coating" refer to a material that is partially or entirely placed on one or more layers to promote adhesion between that layer and another surface. An "adhesive layer" refers to a polymer-based material co-extruded with other layers to provide adhesion between two other layers. In the base membrane of a recyclable membrane, the adhesive layer may be positioned between a polar layer and a compatibilizer layer. The adhesive layer can also be used to provide adhesion for any other layers that may be present in the base membrane. The adhesive layer may also contain materials for other functions such as moisture barrier. In some embodiments, one or more adhesive layers in the base membrane contain a vinyl polymer with maleic anhydride-grafted functional groups.

[0052] An "adhesive," "adhesive layer," or "adhesive coating" is positioned between two films or layers to hold the two materials in their relative positions and prevent undesirable delamination. Unless otherwise specified, an adhesive layer or coating may have any suitable composition to provide the desired level of adhesion to one or more surfaces in contact with the adhesive layer material.

[0053] The base membrane of a recyclable membrane may contain other functional layers, such as a host layer, a coloring layer, or a barrier layer, as long as the amount of these layers does not impair the overall recyclability of the membrane. Specifically, the base membrane layers may contain recycled contents, such as post-consumer or post-industrial recycled materials. Specifically, the base membrane layers may contain reprocessing waste, such as scraps, from the production of the base membrane or the recyclable membrane itself (i.e., closed-loop industrial recycling).

[0054] Non-limiting embodiments of the base film are shown in Figure 1 , 2 and 3 in. exist Figure 1 In this embodiment, the base film 20 has a polar layer 22 and a compatibilizer layer 24. In this embodiment, the polar layer 22 is directly adjacent to the compatibilizer layer 24, but other embodiments may include an intermediate layer. Additionally, the polar layer 22 and the compatibilizer layer 24 are each shown as outer layers of the base film. In other embodiments, the polar layer and / or the compatibilizer layer are not outer layers.

[0055] Figure 2 An embodiment of a base film 20' comprising two polar layers is shown. A first polar layer 22 is shown as the first outer layer of the base film, and a second polar layer 26 is shown as the second outer layer of the base film. A compatibilizer layer 24 is shown at a preferred location between the first and second polar layers. As discussed above, the first and second polar layers may have the same or different compositions.

[0056] Figure 3 An embodiment of a base film 20” is shown, which includes a first adhesive layer 23 between a first polar layer 22 and a compatibilizer layer 24, and a second adhesive layer 25 between a second polar layer 26 and a compatibilizer layer 24. The compositions of the first and second polar layers may be the same or different. The compositions of the first and second adhesive layers may be the same or different. In some embodiments, the compositions of the first and second polar layers are the same, the compositions of the first and second adhesive layers are the same, and the layer thicknesses are such that the base film is palindromic.

[0057] Figure 1 , 2 Figures 3 and 4 show a preferred embodiment of a base film having a polar layer 22 as an outer layer of the base film 20. However, this is not limiting, and other layers may be present on any one or both outer layers as outer layers of the base film 20.

[0058] like Figure 1 , 2 As shown in Figure 3, a compatibilizer layer (or multiple compatibilizer layers) is closely adjacent to the polar layer. Incorporating the compatibilizer into the recyclable membrane structure allows for efficient use of the compatibilizer because the amount of compatibilizer can be precisely matched to the amount of polar polymer in the structure. Ideally, the compatibilizer layer should be within the same base membrane structure as the polar layer. The compatibilizer layer should be close to the polar layer; ideally, only the adhesive layer is between the two layers. This allows the compatibilizer to be readily available to the polar polymer during recycling and reprocessing. The compatibilizer is used most effectively when it is close to the polar polymer (i.e., the optimal minimum amount of compatibilizer is necessary). Positioning the compatibilizer layer close to (near) the polar polymer is one configuration of the base membrane that allows the recyclable membrane to be recycled in a polyethylene recycle stream without the need for additional compatibilizer. Positioning the compatibilizer layer between the first and second polar layers is an example of a base membrane configuration that allows the recyclable membrane to be recycled in a polyethylene recycle stream without the need for additional compatibilizer.

[0059] Advantageously, the polar layers of the base film are separated from each other by polyethylene-based layers such as adhesive layers or compatibilizer layers. This type of structure affects the stiffness of the film, especially after the base film is oriented. The orientation of this type of structure and the annealing of the base film (such as...) Figure 2 A / B / A or Figure 3 The structures shown in A / C / B / C / A have stiffness comparable to oriented films typically used in “non-recyclable” high-performance packaging such as oriented polyester (OPET) or biaxially oriented nylon (BON). While maintaining stiffness compared to OPET or BON, some embodiments of the base film of the recyclable film additionally offer the advantage of recyclability in the polyethylene reprocessing stream and are often less expensive.

[0060] The base film can have any thickness.

[0061] The production of the base film requires at least extrusion, orientation, and annealing conversion processes. These processes, combined with raw material selection, can impart key properties such as thermal stability and durability. Furthermore, this film is more cost-effective than unoriented or oriented materials made from a single polymer.

[0062] The layers of the base film can be combined (co-extruded) or extruded separately. If done separately, the layers can be combined using known lamination methods, including adhesive lamination or extrusion lamination. Alternatively, the layers of the base film can be added using extrusion coating, solution coating, or any other known conversion method. A combination of extrusion and lamination methods can be used to manufacture the base film. The base film or any specific layer of the base film can be extruded using either a flat die or a ring die method.

[0063] After all layers of the base film have been assembled, the film is oriented. Orientation can be unidirectional (longitudinal or transverse) or bidirectional stretching, thereby increasing the longitudinal and / or transverse dimensions and subsequently reducing the thickness of the material. Bidirectional orientation can be imparted to the film simultaneously or sequentially. The film is then subjected to stretching in either or both directions in the solid phase at a temperature just below the melting temperature of the polymer in the film. In this way, stretching "orients" the polymer chains, thereby altering the physical properties of the film. Simultaneously, stretching thins the film. The resulting film is thinner and can exhibit significant variations in mechanical properties such as toughness, heat resistance, stiffness, tear strength, and barrier properties.

[0064] The orientation of the base film can affect its properties. It has been found that, in the case of longitudinally oriented base films, stretching by at least 2X (twice) results in optimal film properties such as stiffness and appearance. However, in some embodiments, the base film can be stretched to less than 2X. In other embodiments, the base film can be stretched longitudinally by at least 2.5X, 3.0X, 3.5X, 4X, 5X, 6X, or any value in between or more. In other words, the film size increases the original length by a factor of 2, increases the original length by a factor of 2.5, and so on. Biaxially oriented base films can be stretched to similar levels as uniaxially oriented films using a tenter frame method (flat die) or a foaming method (tubular die).

[0065] The annealing method is also important for the properties of the base film. After orientation, the film has embedding stress. Heating the film can release this stress, causing the film to shrink back to its original pre-oriented dimensions. This can be problematic when heat is applied to the base film during the heat-sealing process of recyclable film in packaging applications. The shrinkage of the base film at this time will result in an unsightly appearance of the heat-sealed area of ​​the packaging. Additionally, a film exhibiting shrinkage under heat conditions will be difficult to print markings on, as the process typically uses high temperatures. The annealing process helps to alleviate the embedding stress caused by orientation, and the film will be "heat-set," preventing it from shrinking back to its original size at lower operating temperatures. It has been found that annealing the film at a temperature of approximately 120°C using annealing rollers results in a base film that is easily convertible (printing / lamination / etc.) and can be used as part of a recyclable film that can be heat-sealed to other packaging components without detrimental visual effects.

[0066] The base film can be oriented and annealed online. Known methods such as triple foaming can be used to biaxially oriented and anneal online. The base film can be co-extruded on a flat die system with longitudinal orientation and online annealing. The base film can be co-extruded on a flat die system, stretched longitudinally, then stretched transversely (i.e., tenter frame orientation method), and annealed online. Alternatively, the orientation and annealing processes can be performed separately. Annealing is typically performed online using high-diameter rollers set at a temperature a few degrees lower than the melting point of the polymer or polymer blend present in the film. Annealing can then be performed by any known method, including hot air or IR heating.

[0067] The recyclable films disclosed herein also include sealants. As used herein, a “sealant” is a material, layer, or film that allows the recyclable film to bond to itself or other packaging components to form a package. Sealants can form a bond under the influence of pressure or heat, or a combination of these conditions. Sealants can be in the form of a film or coating and can be continuous or discontinuous (patterned). Alternatively, a base film can perform the function of a sealant. Embodiments of recyclable films may include any known sealants, such as, but not limited to, adhesives, hot melts, cold-sealing materials, heat-sealing films, and heat-sealing coatings.

[0068] The sealant can be a material used as a heat-sealing coating. Heat-sealing coatings are typically thin and can be patterned. Due to the small amount of sealant material required, many different types of heat-sealing coatings can be used without compromising the recyclability of the membrane. Heat-sealing coatings can be, but are not limited to, polyester-based formulations, vinyl / acrylic copolymer-based formulations, or polypropylene-based formulations. Heat-sealing coatings may contain components with low melting temperatures, such as waxes. Heat-sealing coatings containing wax components may have a heat-sealing initiation temperature of 60°C or even lower. Sealants on recyclable membranes can have heat-sealing initiation temperatures of less than 60°C, 85°C, 100°C, or less than 121°C.

[0069] A heat-sealable coating can be applied to a recyclable membrane using any known method. The heat-sealable coating or any other type of sealant can be applied directly to the outer layer of the base membrane. The heat-sealable coating can be applied directly to the outer polar layer of the base membrane. Alternatively, an intermediate material, such as but not limited to printed markings, barrier materials, primers, or adhesives, can be present between the base membrane and the sealant. Figure 4 An embodiment of a recyclable film 10 having a base film 20 and a sealant 40 is shown. Between the base film and the sealant is an optional layer of printed markings 32 and an adhesive 34. This embodiment represents an optimal arrangement of materials for high-performance packaging films, allowing for optimal positioning of the abuse-resistant base film (on the outside), the printed markings (visible through the base film but unaffected by environmental conditions), and the sealant material (allowing for a seal as an outer layer of the film).

[0070] The sealant for a recyclable membrane can be a polymer-based film manufactured in a separate process and subsequently adhered to a base film. Alternatively, the sealant film can be extruded and simultaneously attached to the base film in an extrusion coating operation. The sealant film can be single-layer or multi-layered and can be produced by any known method. Ideally, the sealant film is unoriented and has no embedding stress (i.e., the sealant film has zero or near-zero free shrinkage). Alternatively, the sealant can be oriented and fully or partially annealed.

[0071] Sealant films can contain any type of material that will allow bonding during packaging production operations. The choice of sealing material depends on the method to be sealed and the material / component the recyclable film will be sealed to. Typical materials for heat sealing include linear low-density polyethylene, ionomers, and ethylene-vinyl acetate copolymers, but a wide variety of known sealant materials can be selected.

[0072] Some embodiments of recyclable membranes include multilayer sealant membranes incorporating other layers such as barrier layers, host layers, mechanical strength layers, coloring layers, etc. In practice, sealant membranes may even include additional polar layers and additional compatibilizer layers.

[0073] Figure 5 A preferred embodiment of the recyclable film 10' is shown. The base film 20 has two outer polar layers 22, 26 and a compatibilizer layer 24 between them. The outer polar layer 26 has printed markings 32 applied thereto, followed by a sealant 40. This arrangement provides excellent heat resistance and appearance in high-performance recyclable packaging films. Again, the printed markings are optional, and other layers, such as adhesives, barrier layers, or primers, may be present between the base film and the sealant.

[0074] The sealant in recyclable membranes can be designed for other functions. Sealants often contain additives such as slip agents or anti-caking agents. Sealants may also have anti-fogging properties, tear-resistant properties, high opacity, pigments, anti-scaling properties, or high barrier properties, including but not limited to oxygen or moisture barriers. For example, recyclable membranes may contain titanium dioxide (TiO2) to increase opacity and stiffness for flow packaging applications.

[0075] Sealants can also be formulated to provide a peelable seal. As used herein, a “peelable seal” is a seal that can be separated manually (i.e., by hand, without tools). Seal strength can be tested using ASTM F88, and peelable seals can generate forces between 200 and 2,500 g / in. Peelable seals are often designed for consumer convenience. In the case of recyclable films used as packaging components, peelable seals are highly desirable, allowing the recyclable film to be easily separated from the rest of the packaging component, thus facilitating easy recycling. In some cases, other packaging components may be available for recycling in the same stream, in different streams, designed for disposal (waste stream), or designed for reuse without recycling.

[0076] In some embodiments, the recyclable membrane may be incorporated into a first sealant and a second sealant, such as Figure 6 As shown. Here, the recyclable film 10” has a base film 20 with optional printed markings 32 and an adhesive 34. A first sealant 40 and a second sealant 50 are present, positioned as the outer layer of the recyclable film 10”. In this way, the recyclable film can be sealed on both sides, thereby allowing for overlap sealing (sealing one side of the film to the other) or attaching packaging components (such as accessories) to both sides of the recyclable film.

[0077] Recyclable membranes may also include barrier materials to reduce the rate at which gases or other vapors pass through the membrane structure. Many high-performance packaging structures include barrier materials such as EVOH, foil, metallized films, PVdC, polyamide, or oxide-coated films to achieve the low transit rates required to extend the shelf life of packaged products. Many packaged foods and pharmaceuticals (and other products) are environmentally sensitive and require very limited transit rates through the packaging components. Typically, barrier materials or barrier layers are tuned to low oxygen or moisture transit rates. Barrier materials can be incorporated into the recyclable membrane at any location.

[0078] A barrier layer may be present within the base film of the recyclable membrane. A non-limiting example is a base film having at least one polar layer containing EVOH. EVOH exhibits excellent oxygen barrier properties, which are enhanced upon orientation. The EVOH in the base film provides improved barrier properties, good heat resistance, good thermal stability, printability, and appearance. Furthermore, placing the EVOH in the base film immediately adjacent to a polar polymer compatibilizer creates a material that can be effectively recycled without the need for additional compatibilizers.

[0079] In some embodiments, a barrier layer may be present within the sealant of the recyclable film. Conventional non-recyclable high-performance packaging materials often use extrudable barrier materials such as EVOH or polyamide in multilayer sealant films. This type of sealant film structure can also be incorporated into recyclable films if sufficient compatibilizer is present in the recyclable film to allow the film to be recycled in a polyethylene recycling stream without additional compatibilizer. Typically, if a polar polymer barrier material is incorporated into the sealant, the compatibilizer should also be incorporated into the sealant.

[0080] In some embodiments of recyclable membranes, a barrier layer may be present between the base film and the sealant. An oriented base film provides excellent opportunities for coating application because it possesses suitable heat resistance, low shrinkage, and thermal stability to withstand the processes required for barrier application. For example, an oriented and annealed base film may undergo a metallization process that deposits a thin layer of aluminum onto the outer layer. In some embodiments, the outer layer of the base film may have applied printed markings, followed by the barrier coating. Alternatively, the outer layer of the base film may have a barrier layer applied first, followed by optional printed markings. The barrier coating can be any known chemical substance, such as crosslinked acrylates or partially neutralized acrylic polymers. Thin layers of deposits or coatings can be used in recyclable membranes because the amount of material used can be readily incorporated into the recycling stream without the need for compatibilizers.

[0081] As previously noted, recyclable films can incorporate printed markings. Markings can be incorporated into recyclable films using any known method. High-performance packaging typically transitions to high-speed processes such as rotary gravure printing, flexographic printing, or digital printing. For many applications, printed markings applied to the film exhibit tight repeatability tolerances (i.e., the mark size must be nearly identical for each print). The thermal stability of the oriented and annealed base film described herein can be utilized in these types of printing processes. The base film can have high-quality printing applied to one or both outer layers. Figure 4 , 5 As shown in Figure 6, the printed markings can be located between the base film and the sealant, thereby protecting the markings from external abuse such as scratches.

[0082] Prior to printing, the base film may have an applied primer or another treatment (i.e., corona treatment) to promote good ink wetting and adhesion. Printed markings applied to the outer layer of the base film (i.e., the outer layer of the recyclable film, opposite the side to which the sealant is attached) may also include a protective layer or another layer to create a visual or tactile effect. Printed markings may be incorporated as a continuous layer or applied as a pattern or illustration (an image created by dots). Printed markings may be continuous with the recyclable film or cover only a small portion of the film. Printed markings may be visible from either side or both sides of the recyclable film.

[0083] While the proposed recyclable membrane aims to produce materials suitable for high-performance packaging applications, the membrane can also contain recycled materials. Recycled materials, such as previously used packaging (post-consumer recyclables) or membrane conversion scraps (post-industrial recyclables), can be incorporated into any part of the recyclable membrane. This material may or may not require a compatibilizer, or a compatibilizer may be added during incorporation.

[0084] The base film, sealant, or any other component of a recyclable membrane may incorporate any other additives known for use in packaging films. These additives may include, but are not limited to, nucleating agents, processing aids, pigments, slip agents, or anti-caking agents. Additives may also be "active" in nature, intended to interact with the environment. An example of an active additive is an oxygen absorber.

[0085] Recyclable films can have any total thickness required for the application to which they will be used. Recyclable films for packaging applications can have thicknesses from 1 mil (25.4 micrometers) to 20 mils (508 micrometers). The thickness of recyclable films can be from 1.5 mils (38.1 micrometers) to 10 mils (254 micrometers), or from 2 mils (51.7 micrometers) to 5 mils (127 micrometers).

[0086] The stiffness of the base film and the recyclable film is an important property of the recyclable film described herein. Oriented base films offer improved stiffness compared to previously described recyclable packaging rolls. Some embodiments of base films incorporating two polar layers separated by a non-polar layer (i.e., a compatibilizer layer) exhibit particularly good stiffness characteristics. Surprisingly, the stiffness of the base films described herein has been found to mimic or, in some cases, improve upon the stiffness found in current non-recyclable packaging structures incorporating OPET or BON. The stiffness of the recyclable film can be critical for successful film conversion on currently used packaging equipment. In this way, recyclable films can be adopted in current packaging applications without higher costs or processing inefficiencies. Furthermore, the stiffness of the film used for packaging provides a higher quality feel and is valued by consumers. The stiffness of the recyclable film or base film can be measured using a ring stiffness test.

[0087] The recyclable film described herein possesses heat resistance for use as a high-performance packaging film. The base film is configured to withstand the high temperatures that the packaging film may encounter, such as, but not limited to, heat from film conversion, high-temperature heat-sealing units, high-temperature processing such as heat filling or retorting, or high-temperature consumer use such as microwave heating. Among other properties, the heat resistance is demonstrated by low shrinkage. When subjected to high-temperature environments, the recyclable film should not shrink or otherwise deform. For example, heat-sealed areas on high-performance packaging should be smooth and clean, without damage or any signs of shrinkage or wrinkling.

[0088] The recyclable film disclosed herein is superior to previously developed recyclable films. Films using only polyethylene materials are prone to abrasion and durability issues. Films using polar materials such as polyamides offer increased heat resistance and durability, but may still fall short of currently available non-recyclable films. However, the recyclable film described herein possesses heat resistance and durability that mimics non-recyclable films with a BON or OPET outer layer. Examples employing oriented and annealed base films with a polar material outer layer are particularly advantageous for obtaining recyclable films suitable for high-performance packaging that can be converted and dispensed while maintaining a very good appearance.

[0089] The material selection and processing conditions disclosed herein are crucial for obtaining low-shrinkage, heat-resistant materials. The use of polar polymers such as polyamides in the base film, combined with orientation and annealing under appropriate conditions, produces films exhibiting low shrinkage and good thermal stability under target conditions. The analytical method for testing the suitability of materials for high-performance packaging applications is the free shrinkage method described herein. When subjected to heat less than or equal to 90°C, the base film may have a longitudinal shrinkage rate of 10% or less; or less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, or less than 1%. When subjected to heat less than or equal to 90°C, the base film may have a transverse shrinkage rate of 10% or less; or less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, or less than 1%. Preferably, when exposed to heat less than or equal to 90°C, the base film has a longitudinal shrinkage rate of less than 7% and a transverse shrinkage rate of less than 1%. Preferably, when exposed to heat of 90°C or less, the base film has a longitudinal shrinkage rate of less than 5% and a transverse shrinkage rate of less than 5%. When exposed to heat of 90°C, the base film may have a longitudinal shrinkage rate of less than 2% and a transverse shrinkage rate of 0%. When exposed to heat of 90°C, the base film may have a longitudinal shrinkage rate of less than 1% and a transverse shrinkage rate of 0%.

[0090] Similarly, when subjected to heat of 90°C or less, the recyclable membrane may have a longitudinal shrinkage rate of 10% or less; or less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%. When subjected to heat of 90°C or less, the recyclable membrane may have a transverse shrinkage rate of 10% or less; or less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%. Preferably, when exposed to heat of 90°C or less, the recyclable membrane has a longitudinal shrinkage rate of less than 7% and a transverse shrinkage rate of less than 1%. Preferably, when exposed to heat of 90°C or less, the recyclable membrane has a longitudinal shrinkage rate of less than 5% and a transverse shrinkage rate of less than 5%. When exposed to heat of 90°C, the recyclable membrane may have a longitudinal shrinkage rate of less than 2% and a transverse shrinkage rate of 0%. When exposed to heat at 90°C, the recyclable membrane can have a shrinkage rate of less than 1% in the longitudinal direction and 0% in the transverse direction.

[0091] As already discussed, recyclable films may contain barrier layers or barrier materials. Recyclable films can exhibit the high oxygen or moisture barrier properties that packaging applications may require. The barrier layer can also protect the outer film / layer from migration from the packaging contents (e.g., oil, etc.). When tested according to ASTM F1927 at 0% RH and 23°C, recyclable films can have a thickness of less than 1,000 cm⁻¹. 3 / m 2 / 24-hour oxygen delivery level. Recyclable membranes can have a value of less than 100, less than 10, less than 5, or less than 1 cm. 3 / m 2 / 24-hour oxygen transport level. When tested according to ASTM F1249 at 90% RH and 23°C, the recyclable membrane can achieve less than 100 g / m³. 2 / 24-hour moisture transfer level. Recyclable membranes can have a moisture transfer level of less than 10, less than 5, or less than 1 g / m³. 2 / 24-hour moisture transport level.

[0092] For high-performance packaging applications, recyclable films can have near 100% visible light blocking (light-opaque), or at least 50% visible light blocking. This type of recyclable film is suitable for packaging applications where it is not desirable to see the product or where light is detrimental to the product's shelf life.

[0093] Alternatively, recyclable films can have high light transmittance and transparency, as this is often desirable for packaging applications where the product is to be viewed through the packaging material. The base film can have a transparency greater than 80%, 85%, or 90%. Ideally, when measured according to the instructions and teachings of ASTM D-1003, the base film should have a transparency of at least 95%, at least 95.5%, at least 96%, at least 96.5%, at least 97%, at least 97.5%, at least 98%, at least 98.5%, at least 99%, at least 99.5%, or 100%, and all values ​​in between. Transparency is defined as the percentage of transmitted light that deviates from the incident light by less than 2.5 degrees. As is known in the art, the transparency of the base film can be affected by material selection and orientation conditions.

[0094] As already discussed, the appearance of packaging materials is a key performance criterion for many high-performance packaging applications. In addition to high transparency and high-quality printed markings, a high-gloss appearance is often desired. Base films can have gloss levels greater than 50, 60, 70, or even 80 (45° gloss, unit, ASTM D2457), comparable to other packaging materials such as BON. This type of gloss is superior to recyclable packaging films containing only polyethylene base materials.

[0095] The recyclable films containing a base film and a sealant described herein can be recycled after their initial use. Generally, the term recyclable means that the product is suitable for reuse. An example of a specific context for recyclability is the second reuse of plastic grocery bags to hold other items. The plastic bags have already been reused and recycled. In a slightly different context, recyclable means that a product is suitable for reuse after being transformed into a new product. As used herein, the term "recyclable" means that the film can be transformed into a new, useful item through reprocessing in the polyethylene waste stream. Reprocessing may require washing, separation, melting, and shaping, among many other steps. Typically, when reprocessing plastic packaging, the material is mechanically cut into small pieces and then melted to reformate into a new product. If multiple incompatible materials are present in the packaging, they interact during reprocessing, resulting in gels, brittle materials, poor appearance, and products that are generally unusable or of poor quality. The use of the term "recyclable" indicates that these drawbacks are generally not present. Qualification as a recyclable material is not regulated by any specific body, but rather can be obtained from specific groups such as the Association of Plastic Recyclers (APR) and How2Recycle. TM The recyclable membranes disclosed herein are applicable to “physical store recycling” recycling streams. These streams accept the following: 100% polyethylene bags, wrappers, and membranes; very close to 100% polyethylene bags, wrappers, and How2Recycle-approved polyethylene-based carrier packaging with or without compatibilizer technology. Introducing the recyclable membrane into any of these recycling pathways via reprocessing should not require additional compatibilizers.

[0096] When used as a packaging film, the recyclable film can be sealed to itself, or to a similar film or one or more other packaging components. Other packaging components may include, but are not limited to, zippers, fittings, cups, or trays. The packaging may also include other components such as patches, liners, sleeves, or labels. The packaging may be formed from one, two, three, or more different packaging components.

[0097] Recyclable films are sealed or attached to themselves or other packaging components to create airtight packaging. Sealing can be achieved through adhesives, heat sealing, ultrasonic sealing, cold sealing, RF welding, or any other known combination method. Airtight packaging is critical for a wide range of products, including food, beverages, pharmaceuticals, consumer goods, and other sensitive products. Airtight packaging helps prevent damage to the product. For many products, achieving a good heat seal to produce consistent airtight packaging is crucial. The advantages of the recyclable films disclosed herein are their superior heat resistance, and therefore, the ability to form airtight packaging on a more reliable basis. The combination of the high heat resistance of the base film and the sealant layer providing a superior seal is a key advantage of the films presented herein.

[0098] The advantages of some embodiments of the recyclable films disclosed herein also lie in their provision of a sealant that achieves a peelable seal when heat-sealed to other packaging components. Consumers can open the packaging in a variety of ways, including manual peel-opening. Peelable seals are those that can be peeled open by hand by the consumer without the use of other tools. Consumers can grasp both parts of the packaging and pull the packaging open at the heat seal. Peelable seals allow consumers easy access to the product inside the packaging. In some cases, peelable seals can also be manually reclosed and resealed. Additionally, recyclable films can have peelable heat seals to allow for easy separation of packaging components. This advantageously allows the packaging components to be properly disposed of into other recycling or waste streams. Packaging components included in hermetically sealed packaging can be recycled in the same stream as the recyclable film, recycled in a different stream, or not recycled at all.

[0099] Recyclable films can be used in any type of airtight packaging, including but not limited to pouches, bags, flow packaging, trays / lids, chubs, bulk bags, and blister packs. Recyclable films can be used to package any type of product, including but not limited to dry foods, liquids, meat, cheese, fresh foods, frozen foods, beverages, pharmaceuticals, health foods, cosmetics, perishable products, cleaning agents, chemicals, wet wipes, medical products, electronic devices, pet food / snacks, and bulk products.

[0100] Some embodiments of packaging using the recyclable film disclosed herein are in the form of pouches, bags, or sachets. In this form, the recyclable film serves as at least one sidewall of the packaging, or in some cases, as all sidewalls. Pouches or bags may be sealed with fin-lock or overlap-lock constructions. Sachets may have side seals and end seals. Fittings or other closures may be sealed to any portion of the recyclable film.

[0101] Ideally, the packaging is configured so that after emptying the contents, the package can be fully opened and the package components can be separated as needed to achieve optimal emptying (product removal), rinsing, and recycling. Product removal means that there is no significant amount of product in the package that would contaminate the recycling process. Complete product removal can be determined by visual inspection. Complete product removal can be achieved by rinsing the opened package components with water until most or all of the product is removed.

[0102] Separation of packaging components can be facilitated by the aforementioned peelable seals or by any other means such as weakened threads or tearable perforations. In some cases, recyclable films and other packaging components are designed to be easily torn or cut to facilitate opening. In some embodiments, the packaging components remain attached to the recyclable film and are capable of being recycled in the same recycling flow.

[0103] Some embodiments of recyclable films can be used in chub-style packaging. These films may have sealants (such as...) on both main surfaces of the recyclable film. Figure 6 (As shown), to accommodate overlap sealing. Recyclable films can have very little longitudinal and / or transverse shrinkage, such as 5%, which is optimal for certain cylindrical packaging applications.

[0104] The size of the packaging using recyclable film is not limited. The packaging can be very small (a few square inches) or very large, like a bulk container liner. The bulk liner can be made of recyclable film, and in some embodiments, the bulk liner can be made of several layers of recyclable film. The bulk liner may have fittings attached to any surface.

[0105] In some embodiments, the recyclable membrane is in the form of a lid attached to a tray or cup. The tray or cup can be flexible, semi-rigid, or rigid, and can be made of any material, including but not limited to polyester, polyethylene, polystyrene, polypropylene, paper, metal, glass, or ceramic. This embodiment... Figure 7a and 7b As shown in the diagram, package 60 has a lid 62 that is connected to tray 64 by a heat seal 66. Figure 7a It is an airtight, sealed package, number 60. Figure 7b The image shows package 60 after the lid 62 has been manually removed from tray 64. The lid 62, tray 64, or both the lid and tray can be recyclable film.

[0106] The recyclable membrane described in this article can also be used in applications unrelated to packaging.

[0107] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All disclosures and patents specifically mentioned herein are incorporated herein by reference for all purposes.

[0108] The following examples are provided for illustrative purposes only and are not intended to limit the scope of the invention in any way. In fact, various modifications of the invention will become apparent to those skilled in the art from the foregoing description and the following examples, in addition to those shown and described herein, and fall within the scope of the appended claims.

[0109] Example membrane

[0110] Example A: Co-extruded film production on a blown film line with online longitudinal orientation. The film structure is polyamide / bond / PE / bond / polyamide. The polyamide used is 5034FDX40 (PA6 / 66 copolyamide available from UBE Industries, Ltd.). The intermediate PE layer uses a blend of mLLDPE (available from ExxonMobil). TM The obtained materials are 2705HH and 1018HA. The materials are oriented longitudinally inline by 3 times and annealed at approximately 121°C using two high-diameter annealing rollers.

[0111] Example B: Co-extruded film production on a blown film line with online longitudinal orientation. The film structure is polyamide / bond / PE / bond / polyamide. The polyamide used is 5034FDX40 (PA6 / 66 copolyamide available from UBE Industries, Ltd.). The middle PE layer uses HDPE (available from ExxonMobil). TM The obtained HTA 108). The material was oriented longitudinally inline by 3 times and annealed at approximately 121°C using two high-diameter annealing rollers.

[0112] Example C: Production of a co-extruded film with a polyamide / bond / LLDPE / bond / polyamide structure on a flat die. The polyamide used is Nylon 6 (H135), available from AdvanSix. H135. The LLDPE is Dowlex 2036G, available from Dow Chemical Company. The layer distribution is 15% / 10% / 50% / 10% / 15%. The material is co-extruded inline with a longitudinal orientation of 3 times and annealed at approximately 121°C using two high-diameter annealing rolls.

[0113] Comparative Example 1: Data collection on a standard 48ga OPET.

[0114] Comparative Example 2: Data collection on a standard 60ga BON.

[0115] Comparative Example 3: All polyethylene films were run on a blown film line and oriented longitudinally online. The final film thickness was 0.8 mils.

[0116] Comparative Example 4: 4-mil membrane produced using blown film co-extrusion. The structure is polyamide / bond / polyamide / EVOH / polyamide / bond / polyethylene. This structure is unoriented.

[0117] Tests and data

[0118] Ring stiffness was tested using a tensile testing unit equipped with appropriate load cells and a bending device. The bending device typically consists of the upper breaker plate and the support. Membrane samples were cut into 4-inch x 4-inch specimens, noting the longitudinal direction of the membrane. Ten membrane samples were tested, five each in the longitudinal and transverse directions. The test was run at a crosshead speed of 5 inches per minute. The membrane was inserted into the support with the outer edge of the material facing upwards. For longitudinal data, the sample was mounted with the longitudinal direction perpendicular to the length of the support. For transverse data, the sample was mounted with the transverse direction perpendicular to the length of the support. The test was started with the upper crosshead lowered so that the bottom edge of the breaker plate was slightly above the top of the ring of the specimen. The device should be set to stop after 0.5 inches. Individual readings of stiffness (gram force) were recorded, and the average value was reported. Ring stiffness data are reported in Table 1. The data indicate that the base membrane disclosed herein has stiffness similar to that of BON and OPET films.

[0119] Table 1: Ring Stiffness Data

[0120] membrane samples Ring stiffness (Crystal) MD / TD Example A 1.4 / 2.0 Example B 1.2 / 1.6 Example C 1.6 / 1.5 Comparison Example 1 1.3 / 1.4 Comparison Example 2 1.4 / 1.5

[0121] The tensile properties of a film play a crucial role in processing and packaging performance during film conversion. As previously mentioned, a base film with low elongation properties can be useful when printing during standard high-performance packaging printing operations. The tensile properties of the films were characterized using ASTM D882, and the elongation at break is recorded in Table 2. The data show that the longitudinal elongation of the example films is comparable to that of BON and OPET films. In contrast, the oriented film without a polar layer (Comparative Example 3) exhibits a significantly higher longitudinal elongation at break. Additionally, the unoriented film containing a polar layer (Comparative Example 4) exhibits a significantly higher longitudinal elongation at break. For the film to be converted into high-performance packaging, the longitudinal elongation at break must be less than 100%.

[0122] Table 2: Elongation at Break

[0123] membrane samples Elongation at break (MD / TD) Example A 70 / 417 Example B 45 / 439 Example C 31 / 198 Comparison Example 1 91 / 78 Comparison Example 2 69 / 71 Comparison Example 3 127 / 604 Comparison Example 4 391 / 408

[0124] "Free shrinkage" is defined as the value obtained by measuring unconstrained shrinkage for five seconds at 90°C. Five samples were cut into 10cm longitudinally and 10cm transversely. Each sample was fully immersed in a 90°C water bath for at least 5 seconds. The distance between the ends of the shrunken sample was measured. The difference between the shrunken sample and the initial 10cm measurement distance was multiplied by 10 to obtain the percentage shrinkage of the sample in each direction. For a given longitudinal shrinkage value of a membrane sample, the longitudinal shrinkage of the five samples was averaged, and for a transverse shrinkage value, the transverse shrinkage of the five samples was averaged. Table 3 shows the free shrinkage data.

[0125] Table 3: Free Contraction

[0126] Vertical (%) Horizontal (%) Example A 10 2 Example B 5 1 Example C 6 0 Comparison Example 1 0 0 Comparison Example 2 1 2

[0127] Optical transparency was measured using the transparency port of the BYK Gardner HazeGard, according to its instructions and the teachings of ASTM D-1003-13. Transparency is defined as the percentage of transmitted light that deviates from the incident light by less than 2.5 degrees. Table 4 presents the transparency data (average of four measurements).

[0128] Table 4: Transparency

[0129] Optical transparency (%) Example A 99.1 Example B 96.9 Example C 89.6 Comparison Example 1 97.2 Comparison Example 2 98.6

[0130] The degree of orientation imparted to polymeric and transparent films is measured using the following test method. A lightbox (e.g., the Porta Trace Light Box from Gagne, Inc.) is set up with polarizing films on its surface. The first polarizing film is installed with its polarization direction oriented at a 45-degree angle to the side edge of the lightbox. A second polarizing film should be installed 4 to 10 inches above the first polarizing film, with its polarization direction oriented at a 90-degree angle to the first polarizing film. The film sample to be tested should be placed between the polarizing films, with the film longitudinally aligned with the side of the lightbox. The color of the film can be determined by observing the sample passing through the second polarizing film after the lightbox is turned on. The degree of orientation can be assessed by the color observed. Films with little or no orientation appear black, gray, or white (or possibly a mixture of these colors). As orientation increases, other colors will appear, starting with yellow and gradually progressing to orange, blue, and purple. The colors are often mixed or varied.

[0131] Various membrane structures were co-extruded and their orientation tested. Orientation was also performed on some membrane samples. The results are shown in Table 5. The test results demonstrate how this test can be used to verify membrane orientation.

[0132] Table 5

[0133]

[0134]

[0135] Throughout this specification, references to "one embodiment," "some embodiments," "one or more embodiments," or simply "embodiment" mean that a feature, structure, material, or characteristic described in connection with that embodiment is included in at least one possible embodiment. Therefore, phrases such as "in one or more embodiments," "in some embodiments," "in one embodiment," or "in an embodiment" appearing in various places throughout this specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, features, structures, materials, or characteristics may be combined in any suitable manner.

[0136] Unless otherwise stated, all figures used in this application to indicate dimensions, quantities, ranges, limits, and physical and other properties should in all cases be understood to follow the term "about". Therefore, unless expressly stated to the contrary, the numerical parameters presented in this application are approximations that can vary according to the desired properties sought by a person skilled in the art using the teachings disclosed herein without excessive experimentation.

[0137] The disclosed descriptions, examples, embodiments, and drawings are illustrative only and should not be construed as limiting. This invention includes, but is not limited to, the disclosed descriptions, examples, embodiments, and drawings; however, it is not limited to the device descriptions, examples, embodiments, or drawings. As briefly described above, the reader should assume that features of one disclosed embodiment can also be applied to all other disclosed embodiments unless explicitly indicated to the contrary. Modifications and other embodiments will be apparent to those skilled in the art of packaging, and all such modifications and other embodiments are intended and are considered to be within the scope of this invention.

[0138] Exemplary embodiments

[0139] A recyclable membrane comprising:

[0140] a) A base membrane, said base membrane comprising:

[0141] i) A first polar layer containing a polar polymer, and

[0142] ii) A compatibilizer layer containing a polar polymer compatibilizer,

[0143] b) Sealant, and

[0144] c) Optionally, a printed mark is positioned between the base film and the sealant.

[0145] The base film is oriented and annealed such that when tested according to ASTM D2732 using a bath temperature of 90°C, the base film has a free shrinkage value of less than 10% in both the longitudinal and transverse directions.

[0146] B. A recyclable membrane comprising:

[0147] a) A base membrane, said base membrane comprising:

[0148] i) A first polar layer containing a first polar polymer,

[0149] ii) A second polar layer containing a second polar polymer, and

[0150] iii) A compatibilizer layer located between the first polar layer and the second polar layer, the compatibilizer layer comprising a polar polymer compatibilizer; and

[0151] b) Sealant

[0152] C. A recyclable membrane comprising a base membrane, said base membrane comprising:

[0153] a) A first outer layer containing polyamide;

[0154] b) A compatibilizer layer, the compatibilizer layer comprising:

[0155] i) polyethylene, polyethylene copolymers or blends thereof, and

[0156] ii) Compatibilizers containing low molecular weight anhydrides or carboxylic acid-functionalized polyethylene;

[0157] c) A first adhesive layer located between the first outer layer and the compatibilizer layer;

[0158] d) A second outer layer containing polyamide; and

[0159] e) A second adhesive layer located between the compatibilizer layer and the second outer layer.

[0160] D is a recyclable membrane according to Example C, which further includes a sealant.

[0161] E. A recyclable membrane according to any other embodiment, wherein the polar polymer is a polyamide or a ethylene vinyl alcohol copolymer.

[0162] F is a recyclable membrane according to any other embodiment, wherein the first polar layer is the outer layer of the base membrane.

[0163] G is a recyclable membrane according to any other embodiment, wherein the first polar layer is the outer layer of the recyclable membrane.

[0164] H is a recyclable membrane according to any other embodiment, wherein the base film is oriented and annealed such that when tested according to ASTM D2732 using a bath temperature of 90°C, the base film has a free shrinkage value of less than 10% in both the longitudinal and transverse directions.

[0165] I. A recyclable membrane according to any other embodiment, wherein the base membrane has a free shrinkage value of less than 5% in both the longitudinal and transverse directions when tested according to ASTM D2732 using a bath temperature of 90°C.

[0166] J is a recyclable membrane according to any other embodiment, wherein the sealant is a membrane that, when tested according to ASTM D2732 using a bath temperature of 90°C, has a free shrinkage of less than 1% in the longitudinal direction and less than 1% in the transverse direction.

[0167] K, according to embodiment B or D, is a recyclable membrane that further includes printed markings between the base film and the sealant.

[0168] L is a recyclable membrane according to any other embodiment, wherein the base membrane is oriented such that the longitudinal elongation at break of the base membrane is less than 100%.

[0169] M is a recyclable membrane according to Example C, wherein the polyethylene in the compatibility layer is LLDPE.

[0170] N, according to any other embodiment, a recyclable membrane further includes a barrier material between the base membrane and the sealant.

[0171] According to any other embodiment, the recyclable membrane further includes a second sealant such that the base membrane is located between the sealants.

[0172] P. A package comprising a recyclable film according to any of the foregoing embodiments and optionally additional packaging components.

[0173] Q is the packaging according to Example P, wherein the recyclable film is heat-sealed to itself or the additional packaging assembly, and the heat seal strength is between 200 g / in and 2,500 g / in when tested according to ASTM F88.

[0174] R is the packaging according to embodiment P or Q, wherein the recyclable film is configured to be separate from any other packaging components that may be present.

[0175] S is a package according to embodiment P, Q, or R, wherein the package is configured to be opened to completely remove the product.

Claims

1. A recyclable membrane, comprising: a) A base membrane, said base membrane comprising: i) Contains a first outer layer of polyamide. ii) Compatibilizer layer, iii) A first adhesive layer located between the first outer layer and the compatibilizer layer. iv) A second outer layer containing polyamide, and v) A second adhesive layer located between the compatibilizer layer and the second outer layer. The compatibilizer layer comprises 1) low molecular weight anhydride or carboxylic acid functionalized polyethylene, and 2) polyethylene, polyethylene copolymers, or blends thereof; and b) Sealant; This involves orienting and annealing the base film.

2. The recyclable membrane according to claim 1, further comprising printed markings between the base film and the sealant.

3. The recyclable membrane according to claim 1, wherein the base film is oriented and annealed such that when tested according to ASTM D2732 using a bath temperature of 90°C, the base film has a free shrinkage value of less than 10% in both the longitudinal and transverse directions.

4. The recyclable membrane according to claim 1, wherein the base membrane is oriented such that the longitudinal elongation at break of the base membrane is less than 100%.

5. The recyclable membrane according to claim 1, further comprising a barrier material between the base membrane and the sealant.

6. The recyclable membrane of claim 1, further comprising a second sealant such that the base membrane is located between the sealants.

7. A package comprising a recyclable film according to any one of the preceding claims and optionally additional packaging components.

8. The packaging according to claim 7, wherein, The recyclable film is heat-sealed to itself or the additional packaging assembly, and the heat seal strength is between 200 g / in and 2,500 g / in when tested according to ASTM F88.

9. The packaging according to claim 7, wherein, The recyclable membrane is configured to be separate from any other packaging components that may be present.

10. The packaging according to claim 7, wherein, The packaging is configured to be opened to completely remove the product.

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