WO2025174365A1

WO2025174365A1 - Heat resistant recycle-ready retort packaging with limited retort shock

Info

Publication number: WO2025174365A1
Application number: PCT/US2024/015769
Authority: WO
Inventors: Florian Chapalain; Bert De Schoenmaker; Robert J. Massey
Original assignee: Amcor Flexibles North America Inc
Current assignee: Amcor Flexibles North America Inc
Priority date: 2024-02-14
Filing date: 2024-02-14
Publication date: 2025-08-21
Anticipated expiration: 2026-08-14

Abstract

A laminated recyclable polypropylene-based film suitable for retort packaging having an oriented exterior film, a barrier layer, and a sealing layer. The retort packaging film has a total composition including high levels of polyolefin-based polymers and polypropylene-based polymers such that the material can be processed efficiently in a polypropylene recycling process. Advantageously, the film retains the properties required to suitably withstand the retort process and produce a high-quality retort package for forming shelf-stable packaged product.

Description

HEAT RESISTANT RECYCLE-READY RETORT PACKAGING WITH LIMITED

RETORT SHOCK

TECHNICAL FIELD

[001] This disclosure is related to film structures, specifically retortable packaging films and the packaged products made therefrom. The packaging films described herein may be recyclable in a polyolefin-based recycling process with the structure specifically designed to provide a comparative alternative to higher cost structures utilizing an oxide or metal based barrier layer.

BACKGROUND

[002] Retort operations are used for the sterilization and thermal processing of food or other products contained within hermetically sealed packaging components. Food or other products are packed and sealed in a retortable package, such as a pouch, and transferred to an autoclave unit where it is subjected to temperatures generally exceeding the boiling point of water for an extended period. The autoclave process also uses over-pressure to complete the sterilization step.

[003] Specialized flexible packaging films are used for applications which use an autoclave sterilization process to create a shelf-stable or sterilized product. Commercially available shelf-stable products such as pre-cooked rice, moist pet foods, or tuna are available in flexible packaging formats such as stand-up pouches, lidded trays or flow-wrap. The packaged products can be stored at ambient conditions for several months or years, depending on the barrier of the packaging films.

[004] Flexible packaging films used for in-package sterilization often have many different layers with each layer contributing one or more important attributes necessary for the high demand application. For example, the packaging films may require high stiffness and high heat resistance to work well in a high-speed packaging process. The packaging film must be able to withstand the high temperatures and pressure changes of the sterilization process without losing seal integrity or becoming unappealing in appearance.

[005] A typical flexible packaging film intended for a sterilized product application may include a combination of materials such as polyester or polyamide, providing excellent heat resistance, dimensional stability, and stiffness; aluminum foil and/or silicon or aluminum oxides, providing high barrier and stiffness; and/or polyolefins providing suitable sealing characteristics.

[006] More recent packaging film structures have been designed to be specifically recyclable in a polyolefin-based recycling stream. A typical recyclable structure for retort application utilizes at least 80% by weight of polyolefin-based polymers, such as polypropylene, and includes a barrier of a metal layer or an inorganic oxide layer. Although these recyclable structures are useful and effective for certain products that require high barrier capabilities, these structures can be cost prohibitive for products not requiring as high a barrier resulting in a lessened incentive to use recyclable materials. [007] Compared to barriers of metal or inorganic oxides, ethylene-vinyl alcohol ("EVOH") copolymers are well-known for their oxygen gas barrier properties, and may be less expensive. Effectiveness of an EVOH oxygen barrier is highly dependent on relative humidity. That is, exposure to humidity results in reduced capacity of the EVOH to provide a gas barrier, which can be measured as an oxygen transmission rate (OTR). As an oxygen gas barrier, lower OTRs are desired. In coextruded films, in addition to its oxygen barrier properties, EVOH has excellent durability and good appearance, which are desired features in retortable containers that are recycle-ready.

[008] Existing non-recyclable films for retort may utilize a protective high moisture barrier outer layer on an EVOH-containing film. Even so, an increase in OTR during exposure of retortable containers to retort conditions is expected due to exposure of the container to wet-heat conditions. This temporary increase in OTR is referred to as retort-shock. The loss in oxygen barrier/increase in OTR is, for the most part, reversible and the oxygen barrier recovers as the material dries out. Some EVOH-containing retortable containers in the state of the art can experience long retort-shock recovery times in that only after a longer period of time (days/weeks) does the oxygen barrier become fully established again. In addition to the presence of moisture at an outer layer exterior to the package during the retort process, retort products are often wet products which provide a very humid environment within the package interior.

[009] Despite this retork-shock effect, there remains an on-going need within the market to provide EVOH-containing films for packaging that provide improved retort-shock recovery and a lower oxygen transmission rate when packing wet products, a long shelf-life, and a high barrier to oxygen in a recycle-ready structure.

SUMMARY

[010] Described herein is a flexible laminated packaging film that can be used in retorted product applications having the important advantage of being recyclable in a polyolefin recycling stream, but not having the higher material costs associated with the construction of a metalized or inorganic barrier layer. Despite having a composition with a high polyolefin content, the retort packaging film retains the characteristics that allow it to function well in high-speed packaging operations and survive the sterilization cycle while retaining good appearance, good barrier properties, and hermetic integrity.

[Oil] The retort packaging films described herein have an exterior polypropylene-based multilayer film with an embedded barrier layer comprising ethylene-vinyl alcohol ("EVOH") copolymers and a polypropylene-based sealing layer. Accordingly, the retort packaging film has a total composition including at least 80% polyolefin-based polymers, by weight. More specifically, the retort packaging film has a total composition including at least 80% polypropylene- based polymers, by weight.

[012] In some embodiments, the retort packaging film has a pair of thin barrier layers of EVOH positioned as an interior-most layer of the polypropylene-based multilayer film. Within this multilayer structure intervening tie layers are utilized to promote adhesion and compatibility amongst the layers of the multilayer structure.

[013] Preferred embodiments of the retort packaging film have a barrier layer containing EVOH deposited on an interior surface of the exterior multilayer polypropylene-based film with the film being a machine direction oriented polypropylene-based film.

[014] In certain embodiments, the sealing layer of the retort packaging film is comprised of a retort stable polypropylene based sealant structure having a low sealing initiation temperature (SIT). The sealing layer can be heat sealed to itself at a sealing temperature of 130°C when sealed for a dwell time of 1 second and at a pressure of 440 N / 15 cm². In some cases, this sealing performance is achieved when the sealing layer contains a polypropylene copolymer having a melt temperature less than or equal to 135°C. Ideally, the exterior polypropylene- based film and the sealing layer are essentially free from polymers other than polyolefins, and more specifically only contain polypropylene based polymers.

[015] A retort package can be formed from one or more of the retort packaging films.

[016] From the perspective of a retort package, it is made from a retort packaging film having a total composition having at least 80% polyolefin-based materials. The retort packaging film has a barrier layer providing a stabilized oxygen transmission rate (OTR) after retort of less than 8.0 cm³/m²/day, preferably less than 6.0 cm³/m²/day, preferably less than 4.0 cm³/m²/day, or preferably less than 2.0 cm³/m²/day. The term stabilized OTR being defined as the point of time, typically in a number of hours, at which the measured OTR difference between two successive data points is less than 0.5cc/m²/24hrs.

[017] Also disclosed herein are shelf-stable packaged products. The shelf-stable packaged product includes a retort packaging film having at least 80% polypropylene-based polymers and a product hermetically sealed within the retort packaging film.

BRIEF DESCRIPTION OF THE DRAWINGS

[018] The disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings, in which:

[019] FIG. 1 is a schematic side view of an embodiment of a retort packaging film;

[020] FIG. 2 is a schematic side view of an embodiment of a retort packaging film;

[021] FIG. 3 is a plan view of an embodiment of a retort package; and

[022] FIG. 4 is a chart showing retort recovery curves for comparative examples and multilayer barrier film examples.

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

DETAILED DESCRIPTION [024] The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the invention. The embodiments may be combined, other embodiments may be utilized, or structural, and logical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. Before the present invention is described in such detail, however, it is to be understood that this invention is not limited to particular variations set forth and may, of course, vary.

[025] Various changes may be made to the invention described and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s), to the objective(s), spirit or scope of the present invention. All such modifications are intended to be within the scope of the disclosure made herein.

[026] Unless otherwise indicated, the words and phrases presented in this document have their ordinary meanings to one of skill in the art. Such ordinary meanings can be obtained by reference to their use in the art and by reference to general and scientific dictionaries.

[027] References in the specification to “one embodiment” indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment.

[028] Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[029] The following explanations of certain terms are meant to be illustrative rather than exhaustive. These terms have their ordinary meanings given by usage in the art and in addition include the following explanations.

[030] As used herein, the term “and/or” refers to any one of the items, any combination of the items, or all of the items with which this term is associated.

[031] As used herein, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise.

[032] As used herein, the terms “include,” “for example,” “such as,” and the like are used illustratively and are not intended to limit the present invention.

[033] As used herein, the terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances.

[034] Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention. [035] As used herein, a “layer” is a homogeneous building block of films. Layers may be continuous or discontinuous (i.e. patterned) with the length and width of the film. As used herein the term “film” is a mono-layer or multi-layer web that has an insignificant z-direction dimension (thickness) as compared to the x- and y-direction dimensions (length and width), not unlike a piece of paper. Films are generally regarded as having two major surfaces, opposite each other, expanding in the length and width directions. Films may be built from an unlimited number of films and/or layers, the films and/or layers being bonded together to form a composite article. A portion of a packaging film may be referred to as a layer or a film.

[036] As used herein, layers or films that are “adjacent” are connected to one another with or without an intervening layer or film. Layers or films that are “directly adjacent” are connected to one another without an intervening layer or film.

[037] As used herein, the term "tie layer," "adhesive", "adhesive layer," or "adhesive coating," refers to a material placed on one or more layers, partially or entirely, to promote the adhesion of that layer to another surface. A “tie layer” refers to a polymeric based material that is coextruded with other layers for the purpose of providing adhesion between two other layers. The tie layers may also contain materials for other functionality such as moisture barrier. In some embodiments, the tie layer(s) in the film contains an ethylene-based or propylene-based polymer that has maleic anhydride grafted functionality.

“Adhesive”, “adhesive layers” or “adhesive coatings” are positioned between two films or layers to maintain the two materials in position relative to each other and prevent undesirable delamination. Unless otherwise indicated, an adhesive layer or a coating can have any suitable composition that provides a desired level of adhesion with the one or more surfaces in contact with the adhesive layer material. Adhesives used in flexible films used for retort applications are typically of a type specifically designed to withstand the uniquely abusive process.

[038] As used herein, a “polyolefin-based polymer” refers to a homopolymer or copolymer having at least one alkene monomer linkage within the repeating backbone of the polymer. Primary examples of polyolefin-based polymers are polyethylene homopolymers and copolymers and polypropylene homopolymers and copolymers. Other examples of polyolefin-based polymers are ethylene vinyl alcohol copolymer and cyclic olefin copolymer.

[039] As used herein, a “polypropylene-based polymer” refers to a homopolymer or copolymer having at least one propylene monomer linkage within the repeating backbone of the polymer. The propylene linkage can be represented by the general formula: [CH2-OH(CH3)]n. Such polypropylene may be a polypropylene impact copolymer, a polypropylene random copolymer or a polypropylene homopolymer, may be syndiotactic or isotactic and/or may or may not be nucleated. A polypropylene-based polymer may be a propylene alphaolefin copolymer.

[040] As used herein, the term “exterior” is used to describe a film or layer that is located on one of the major surfaces of the film in which it is comprised. As used herein, the term “interior” is used to describe a film or layer that is not located on the surface of the film in which it is comprised. An interior film or layer is adjacent to another film or layer on both sides.

[041] Reference to "oxygen transmission rate" (OTR) is the ability of a polymeric film to transmit oxygen therethrough as measured in accordance with ASTM- 1927-14 entitled "Standard Test Method for Determination of Oxygen Gas Transmission Rate, Permeability and Permeance at Controlled Relative Humidity Through Barrier Materials Using a Coulometric Detector." Conditions for measurement include: 1 atm pressure, 23°C, and 50% relative humidity on exterior side and 90% relative humidity on an interior of the package (sealant side being a second exterior side), unless otherwise stated.

[042] As used herein, the term “total composition” is used to describe the entire film structure or package. Any materials, layers or components that are connected to one another in any way are part of the total composition of that article. The packaging films may have high levels of polypropylene-based polymers. The packaging films described herein, and any retort packages made therefrom, may be recyclable in a polypropylene recycling process when the article contains high amounts of polypropylene-based polymers. A mixed polyolefin recycling process can also accept relatively high levels of polyolefins that are not polypropylene, so the articles may also contain high levels of polyolefins that are not polypropylene and still be suitable for recycling.

[043] The films disclosed herein include a sealing layer that allows the film to be bonded to itself or other packaging components, forming a package. The sealing layer may form a bond under the influence of pressure or heat or a combination of these conditions. The sealing layer may form a bond under other influence such as ultrasonic energy. A sealing layer may be in the form of a film (i.e. a single layer film or part of a multilayer film) or a coated layer and may be continuous or discontinuous (i.e. patterned). Sealing layers may be monolayer or multilayer and may be produced by any known processes. Ideally, the sealing layer has not been oriented and has no embedded stress (i.e. the sealant film has zero or near zero free shrink). The sealing layer may be contained within a non-oriented multilayer film.

[044] As used herein, a “retort packaging film” or “retort packaging” is a film, or package made from the film, that can be filled with a product, sealed, and remain hermetically sealed after being exposed to a typical retort sterilization process. Typical retort sterilization is a batch process that uses temperatures from about 100°C to about 150°C, over-pressure up to about 70psi (483 kPa), and may have a duration from a few minutes up to several hours. Common retort processes used for products packaged in flexible films include steam or water immersion.

Food or other products packaged in retort packaging film and retort sterilized can be stored at ambient conditions for extended periods of time (i.e. are shelfstable), retaining sterility. Because the retort process is incredibly abusive, very specialized flexible packaging films have been designed to survive the process.

[045] Current flexible retort packaging films that are not intended for recycling contain a multitude of different materials, designed to provide high performance in demanding applications. The structures commonly contain layers that include polyester, polyamide, polyethylene, polypropylene, metal and/or ethylene vinyl alcohol copolymer. Each layer of the structure is designed to offer properties such as barrier, stiffness, heat resistance, dimensional stability, puncture resistance, seal strength, and visual appeal, to name a few.

[046] To combat the issue of recycling due to the disparate nature of the typical materials used in retort packaging films, recyclable retort packaging films have been developed to provide both high barrier capabilities in combination with a film structure that comprises at least 80% polyolefin content to enable recycling in a polyolefin-based recycling stream. An existing recyclable structure of this type utilizes a barrier material of a metal or inorganic coating such as aluminum oxide (AIOx) or silicon oxide (SiOx). While these barrier coatings are useful and provide an excellent barrier, they may be considered too expensive and therefore undesirable for certain uses requiring less robust of a barrier.

[047] As disclosed herein, a retort packaging film structure has been designed comprising high levels of polyolefin-based materials, specifically, high levels of polypropylene-based materials in combination with a barrier layer of ethylene vinyl alcohol copolymer (“EVOH”). Despite the elimination of many of the materials commonly used in traditional retort packaging, the disclosed structure retains all the required attributes of barrier, heat resistance, appearance and seal integrity. Advantageously, the structure is suitable for easy recycling in a polyolefin-based waste stream and provides excellent retort-shock recovery. Retort-shock being generally defined as the dip in oxygen barrier typically exhibited by films containing EVOH just after the retort process. The presently disclosed recyclable retort packaging film structure displays a quickly recovering oxygen transmission rate (OTR) and a lower OTR at equilibrium for wet product after exposure to retort conditions through its specific layered composition. OTR at equilibrium generally being defined as stabilized wherein the initial time at which the measured OTR difference between two successive data points is less than 0.5cc/m²/24hrs.

[048] The retort packaging film structures described herein use this specific layered composition to both protect the EVOH and move the EVOH positionally away from the wet product to allow the EVOH layer(s) to dry out quickly and regain oxygen barrier effectiveness. Additionally, the portion of the high barrier film structure that contains the EVOH layer(s) is machine direction oriented (“MDO”), providing for the opportunity to 1 ) introduce a buried print layer, 2) add stiffness without adding bulk to the structure and 3) minimize the EVOH and other functional materials to a level that will allow the film to be recycled more easily. This MDO outer film provides certain property improvements including increased stiffness, increased clarity and dimensional stability. The dimensional stability of such a film enables this portion of the film structure to be printed by means typical for flexible packaging converting (i.e. flexographic or rotogravure printing). Printability of this material eliminates the need for added labels, further eliminating additional materials and minimizing the environmental footprint of the package. Good clarity of the outer film gives an optimal view of any buried print layers.

[049] Excellent retort shock recovery for the retort packaging film structure and associated retort packages is provided through the use of a relatively thin layer of a material, such as polypropylene, that provides a limited moisture barrier during and just after the retort process at an exterior layer in conjunction with a layer or layers of EVOH. The exterior layer provides some protection to the EVOH to prevent blistering and when polypropylene is utilized it increases the overall polypropylene content which is helpful and useful for optical sorting in a polypropylene based recycling stream along with offering better protection against humidity when the retort package is conditioned in a moist environment after experiencing retort shock. When a pair of EVOH containing layers is utilized, the first EVOH layer can protect the second EVOH layer and act to allow the two EVOH layers to work independently. Despite the advantages of using a pair of EVOH layers, a single thicker layer of EVOH within the disclosed structure also displays similar shock recovery capabilities.

[050] Using the retort packaging film structure design elements as described herein, a recyclable retort packaging film and product can be achieved. The films and associated package are suitable to be recycled in a polyolefin-based recycling process because of the high polyolefin content. The films are also suitable to be recycled in a polypropylene-based recycling process because of the high polypropylene content. Specifically, the films may have low levels of, or may be free from, materials such as polyester, polyamide, chlorine containing polymers and aluminum foil. The films may contain non-polyolefin-based polymers such as those used in adhesive layers or ink layers, but these are minimized and generally less than 10% of the overall composition, by weight.

The films may contain non-polymeric materials such as barrier materials, but these are minimized and generally less than 10% of the overall composition, by weight. Accordingly, the overall composition of the retort packaging film and associated package contains at least 80% by weight of polyolefin and more specifically at least 80% by weight of polypropylene.

RETORT PACKAGING FILM

[051] Described herein are retort packaging films and laminated polypropylene- based films suitable for retort packaging as well as retort packages and shelfstable packaged products made therefrom.

[052] Various types of packaging materials can be used in retort sterilization processes, including cans, jars and flexible polymeric-based packaging, such as the retort packaging films and laminated polypropylene-based films described herein. The advantages of using flexible packaging for retort applications include weight reduction and a reduction in the energy required to get the contents of the package to the conditions at which the sterilization occurs. A retort packaging film may have a thickness from about 2.5 mil (63.5 micron) to about 10 mil (254 micron), or from about 3 mil (76.2 micron) to about 6 mil (152.4 micron).

[053] Referring now to FIG. 1 , an embodiment of the retort packaging film 10 includes a coextruded exterior machine direction oriented multilayer polypropylene-based film 20 comprising a first polypropylene layer 21 , an EVOH barrier layer 22, and a second polypropylene layer 23, wherein the EVOH barrier layer 22 is positioned as a buried layer between the first polypropylene layer 21 and a second polypropylene layer 23. The barrier layer 22 provides the specific barrier required to preserve a product within a retorted package 60 throughout an extended shelf-life which may be several months or even more than one year. A tie layer 50 is placed between the EVOH barrier layer 22 and first propylene layer 21 and second polypropylene layer 23 to promote adhesion amongst the layers during extrusion. The polypropylene-based film 20 is positioned adjacent to a polypropylene-based sealing layer 30 through the use of an adhesive 40 in a lamination to form the retort packaging film 10.

[054] In a more detailed description of the specific position and composition of the layered structure of the retort packaging film 10, the first polypropylene layer 21 has a first surface 211 and a second surface 212 opposed the first surface 211 , the first surface 211 being the exterior-most layer of the packaging film 10 and the retort package 60 constructed from the film 10 with the second surface 212 being interior and adjacent to the barrier layer 22. A first tie layer 51 is positioned directly adjacent the second surface 212 and the barrier layer 22 and a second tie layer 52 is positioned directly adjacent the barrier layer 22 and a first side 231 of the second polypropylene layer 23, wherein the barrier layer 22 is positioned between the first polypropylene layer 21 and the second polypropylene layer 23. The polypropylene sealing layer 30 has a first surface 301 and a second surface 302 opposed the first surface, the second surface 302 being an exterior surface of the film 10, but an interior surface of the retort package 60 formed from the film 10. The polypropylene sealing layer 30 first surface 301 is positioned adjacent to a second side 232 of the second polypropylene layer 23 with the adhesive 40 positioned between the second side 232 and the first side 301 of the respective second polypropylene layer 23 and 1 polypropylene sealing film 30. The second side 232 may include a print layer

233, wherein the print layer 233 is reverse printed and visible through a position at the exterior of the first surface 211.

[055] Referring now to FIG. 2, in a second embodiment of the retort packaging film 10, a coextruded exterior machine direction oriented multilayer polypropylene-based film 20’ includes the EVOH barrier layer 22 in the form of a pair of distinct layers, wherein the construction includes the EVOH barrier layer

22 and a second EVOH barrier layer 22’. In this embodiment, the pair of EVOH barrier layers 22, 22’ provide improved retort-shock recovery as discussed above. The second polypropylene layer 23 is positioned adjacent to the second EVOH barrier layer 22’ wherein both of the EVOH barrier layers 22, 22’ are positioned as buried layers between the first polypropylene layer 21 and the second polypropylene layer 23. A tie layer 50 is placed between the EVOH barrier layers 22, 22’ and first propylene layer 21 and second polypropylene layer

23 to promote adhesion amongst the layers during extrusion. The polypropylene- based film 20’ is positioned adjacent to the polypropylene-based sealing layer 30 through the use of an adhesive 40 in a lamination to form the second embodiment of the retort packaging film 10.

[056] In a more detailed description of the specific position and composition of the layered structure of the second embodiment of the retort packaging film 10 using the machine direction oriented multilayer polypropylene-based film 20’, the first polypropylene layer 21 has the first surface 211 and the second surface 212 opposed the first surface 211 , the first surface 211 being the exterior-most layer of the packaging film 10 and the retort package 60 that is constructed from the film 10. The second surface 212 of the first polypropylene layer 21 is aligned with the interior of the structure and adjacent to the barrier layer 22. The first tie layer 51 is positioned directly adjacent the second surface 212 and the barrier layer 22 and the second tie layer 52 is positioned directly adjacent the barrier layer 22 and the second barrier layer 22’. In this assembly, a third tie layer 53 is placed between the first side 231 of the second polypropylene layer 23 and the second barrier layer 22’, wherein both of the barrier layers 22, 22’ are positioned as buried layers between the first polypropylene layer 21 and the second polypropylene layer 23. The polypropylene sealing layer 30 first surface 301 is positioned adjacent to the second side 232 of the second polypropylene layer 23 with the adhesive 40 positioned between the second side 232 and the first side 301 of the respective second polypropylene layer 23 and polypropylene sealing layer 30. The polypropylene sealing layer 30 second surface 302 is an exterior surface of the film 10, but an interior surface of the retort package 60 formed from the film 10. The second side 232 may include a print layer 233, wherein the print layer 233 is reverse printed and visible through the exterior of the first surface 211.

[057] The exterior polypropylene-based films 20, 20’ are oriented. As used herein, the term “oriented” indicates that the film has been heated to a temperature lower than the melting point of the material and stretched at least 2X. The amount of orientation imparted on the oriented exterior film can affect the properties thereof. It has been found that in the case of a machine direction oriented exterior film, stretching of at least 2X (2 times) leads to optimal film properties, such as stiffness. However, in some embodiments the oriented exterior film may be stretched to a level less than 2X. In other embodiments the oriented outer film may be machine direction stretched more than 2X, at least 2.5X, 3.0X, 3.5X, 4X, 5X, 6X, any value in between these, or more. In other words, the dimension of the film is increased 2 times the original length, increased 2.5 times the original length, etc.

[058] Also important to the properties of the oriented exterior film is the annealing process. After orientation and subsequent cooling, the films have an embedded stress. Upon heating the film, this stress may be released, causing the films to shrink back to their original, pre-orientation, dimension. This may be problematic when applying heat to the oriented exterior film during the process of heat sealing the retort packaging film 10 in a packaging application. Shrinking of the oriented exterior film at this point will result in a poor appearance in the heat seal area of the package 60. Additionally, a film that exhibits shrink under heat conditions will be very difficult to apply printed indicia to, as this process generally uses high temperatures. The process of annealing can help alleviate the embedded stress caused by orientation and the film will be “heat set” such that shrinkage is minimized at critical operating temperatures. It has been found that annealing the film using annealing rollers, results in an oriented outer film that can be converted easily (printed/laminated/etc.) and is capable of being part of a retort packaging film that can be heat sealed to other packaging components without detrimental visual or functional effects (i.e. without shrinking significantly, delaminating, having print repeat variability, or low seal strength).

[059] The oriented exterior film may be oriented and annealed in line. The oriented exterior film may be coextruded on a flat die system with machine direction orientation and annealing in-line. The oriented exterior film may be coextruded on a flat die system and biaxially oriented, i.e. machine direction stretched followed by transverse direction stretched (i.e. tenter frame sequential orientation process) or simultaneously stretched (i.e. tenter frame simultaneous orientation process) or using a double bubble orientation process and annealed in-line. Alternatively, the processes of orientation and annealing may be done in separate processes. Annealing is typically accomplished in-line through high diameter rollers set up at temperatures a few degrees lower than the melting point of the polymer or blend of polymers present in the film. However, annealing can be done by any known means including hot air or infrared heating.

[060] The oriented exterior film 20, 20’ may be produced using specific polymers and may be oriented using specific conditions which optimize the heat resistance of the film. The oriented polypropylene film may have one or more layers and may have specialized coatings, such as matte lacquer. Any of the layers of the oriented polypropylene film may contain a pigment, such as titanium dioxide, to make the film opaque to visible light. The oriented polypropylene film may be clear to visible light. In some embodiments, the exterior polypropylene- based film is a machine direction oriented polypropylene film that essentially comprises polypropylene. The exterior polypropylene-based film may have, but is not limited to, a thickness of about 25 micron, or of about 30 micron, or of about

35 micron.

[061] The retort packaging film 10 contains at least one polypropylene-based film. As used herein, a “polypropylene-based film” has a composition including at least 80%, or at least 90% polypropylene-based polymer, by weight. In some cases, the polypropylene-based film may be essentially 100% polypropylene- based polymer.

[062] Specifically, the retort packaging film structure 10 has a design such that the heat seal initiation temperature of the sealing layer 30 is low. Even though the sealing layer 30 has a rather low temperature softening point, the sealing layer 30 still has enough integrity to survive the high temperatures of the retort sterilization process along with other abuses a package may endure during distribution and use. The retort packaging film 10 can be formed into retort packages, such as, but not limited to the retort package 60, at lower sealing temperatures, retaining excellent visual appearance. Additionally, the packaging structure maintains excellent barrier properties and visual appearance, even after the film has been formed into a package, filled, hermetically sealed and undergone the retort sterilization process.

[063] The sealing film 30 may contain a material that has a low heat seal initiation temperature (HSIT). In some embodiments of the retort packaging film, the sealing layer contains a polypropylene copolymer having a melt temperature equal to or less than 135°C. [064] The sealing film 30 can be heat sealed to itself (sealing layer-to-sealing layer) at a sealing temperature of less than 130°C using a pressure of 440 N 1 15 cm² and dwell of 1 second. In other words, when heat sealed to itself at these conditions, the sealing layers of the sealing film 30 have formed a strong seal that is more than just tacky. A strong seal can be determined by measuring the force to separate the materials, wherein the average seal strength is at least 4 N/15mm, using ASTM F88 (grip separation at 100 mm/min). In some embodiments, the heat seal strength of the sealing film 30 when heat sealed to itself is greater than 10 N/15mm, 20 N/15mm, or greater than 30 N/15mm.

[065] The retort packaging film 10 is targeted to contain high amounts of polyolefin, specifically polypropylene, such that it may be acceptable for a recycling process. Polyolefins have relatively low heat resistance as compared to materials traditionally used for retort packaging films (i.e. polyester, aluminum foil, polyamide). As a result of the lower heat resistance, the retort packages will be formed using a heat-sealing process with lower temperatures to avoid any shrinking or burn through. The challenge met by the retort packaging films disclosed herein is to incorporate a sealing layer that has a low heat-seal initiation temperature (HSIT) and a high seal strength and seal toughness to survive both retort processing and normal distribution and handling (i.e. drop strength and burst strength). The sealing layer 30 must also contain materials that are approved for food contact during retort conditions, as dictated by governmental agencies for food safety. [066] The retort packaging films described herein contain at least 80% polyolefin-based polymers by weight, and at least 80% polypropylene-based polymers, by weight. Materials that are not polyolefin-based polymers are minimized. The exterior of the packaging film has a heat-resistant polypropylene- based film or alternately the packaging film exterior includes a thin heat resistant lacquer having either a glossy or matte appearance. The interior of the packaging film has a sealing layer that is a polypropylene-based blend of polymers.

[067] Using the packaging film structure design elements as described herein, a recyclable packaging film can be achieved. The film 10 is suitable to be recycled in a polyolefin-based recycling process because of the high polyolefin content. The film 10 is also suitable to be recycled in a polypropylene-based recycling process because of the high polypropylene content. Specifically, the film 10 may have low levels of, or may be essentially free from, materials such as polyester, polyamide, chlorine containing polymers and aluminum foil.

[068] The retort packaging film 10 may have a total composition including at least 80% polyolefin-based polymers, by weight. In other words, considering all materials (polymeric and non-polymeric) within the entire retort packaging film, at least 80% by weight are polyolefin-based polymers. The retort packaging film may have a total composition including a minimum polyolefin-based polymer content of 80%, 82%, 84%, 86%, 88% or 90%, by weight. The retort packaging film may have a total composition including a maximum polyolefin-based polymer content of 100%, 99%, 98%, 97%, 96% or 95%, by weight. For example, the retort packaging film may have a total composition having from 90% to 99% polyolefin-based polymer or the retort packaging film may have a total composition having from 82% to 100% polyolefin-based polymer, by weight.

[069] The retort packaging film 10 may have a total composition including at least 80% polypropylene-based polymers, by weight. In other words, considering all of the materials (polymeric and non-polymeric) within the entire retort packaging film, at least 80% by weight are polypropylene-based polymers. The retort packaging film may have a total composition including a minimum polypropylene-based polymer content of 80%, 85%, 86%, 88% or 90%, by weight. The retort packaging film may have a total composition including a maximum polypropylene-based polymer content of 100%, 99%, 98%, 97%, 96% or 95%, by weight. For example, the retort packaging film may have a total composition having from 80% to 98% polypropylene-based polymer or the retort packaging film may have a total composition having from 80% to 100% polypropylene-based polymer, by weight.

[070] In some embodiments, the retort packaging film 10 has a total composition that includes less than 10% polymers other than polyolefin-based polymers, by weight. In addition to having high polyolefin and polypropylene content, the retort packaging film may have low levels of non-polyolefin polymers, with respect to the total composition. Non-polyolefin polymers that may be included in the retort packaging film include polyamides, polyacrylates and polyurethanes. These polymers may be present in an extruded layer or within a printed ink or adhesive layer. The retort packaging film may have a total composition that includes less than 9%, 8%, 7%, 6% or 5% polymers other than polyolefin-based polymers, by weight.

[071] In some embodiments, the retort packaging film is essentially free from polymers other than polyolefin-based polymers. In other words, any nonpolyolefin polymers that may be present in the retort packaging film do not affect the basic and material properties of the film.

[072] The print layer 233, if present, may take any format, in that it may be a continuous layer or may be pattern applied. The print layer, if present, may be of any type of material typically used for flexible packaging. The print layer may be applied by any suitable process including, but not limited to, digital printing, flexographic printing or rotogravure print. The materials used in the print layer should be chosen to be of the type durable for use in the conditions of retort processing. The print layer 233 may be applied to the second surface 232 of the second polypropylene layer 23, as shown in FIG. 1-2, but other embodiments may have a print layer on the first surface 211 of the first polypropylene layer 21 or any other position of the film 10. Ideally, the print layer 233 is interior to the retort packaging film 10 (i.e. between layers) such that it is protected from scuffing.

[073] The barrier layer 22, 22’of the retort packaging film 10 is generally coextensive with the multilayer polypropylene-based films 20, 20’ and contains the barrier material of EVOH. The barrier layer provides for reduced transmission to gases such as oxygen (i.e. containing an oxygen barrier material). The barrier layer is an interior layer of the retort packaging film 10 to protect the integrity of this important layer. The barrier layer may be multi-layer and contain different layers of barrier materials. The barrier layer may be a blend of multiple barrier materials.

[074] The barrier layer reduces the influx of oxygen through the retort packaging film during the shelf-life of the packaged product (i.e. while the package is hermetically sealed). In some embodiments, before being exposed to a retort sterilization process, the retort packaging film has an average oxygen transmission rate (OTR) value that is less than 8 cm³/m²/day, less than 6 cm³/m²/day, less than 4 cm³/m²/day, less than 2 cm³/m²/day, less than 1 cm³/m²/day, less than 0.5 cm³/m²/day, or less than 0.1 cm³/m²/day (measured according to ASTM F1927 using conditions of 1 atmosphere, 23°C and 50%//90% (inside//outside of the pack) relative humidity (RH)). In some embodiments, after being exposed to a representative retort sterilization process, the retort packaging film has an average stabilized OTR value (initial time at which the measured OTR difference between two successive data points is less than 0.5cc/m²/24hrs) that is less than 8 cm³/m²/day, less than 6 cm³/m²/day, less than 4 cm³/m²/day, less than 2 cm³/m²/day, less than 1 cm³/m²/day, less than 0.5 cm³/m²/day, or less than 0.1 cm³/m²/day. The average OTR value may be near, at or below the minimum detection level of a testing device. The representative retort sterilization process is completed by cutting a DIN A4 sized portion of the retort packaging film and exposing it to a steam sterilization process for 60 minutes at 128°C.

RETORT PACKAGE

T1 [075] Described herein are retort packaging films and laminated polypropylene- based films suitable for retort packaging as well as the retort packages and shelfstable packaged products made therefrom indicated herein as the retort package

60.

[076] Examples of retort package formats include, but are not limited to, a pouch or bag, a stand-up pouch (as shown in FIG. 3), a tray, cup or bowl-and-lid or a flow-wrap. A retort package may be made entirely of one or more retort packaging films as described herein. A retort package may be made of various components, including at least one retort packaging film as described herein. Any components of the retort package that are not of the retort packaging films described herein may also have high levels of polypropylene polymer. In some embodiments of the retort package, the package is made from at least one film as described herein and at least one other component, the other component having at least 90% polypropylene-based polymer, by weight, such that the entire package is recyclable in the polypropylene recycling process.

[077] The retort package includes at least one heat seal to allow for connection of packaging components, formation of the package and hermetic closure of the package. An example of the retort package 60 that includes a retort packaging film 10 and a heat seal 110 is shown as a stand-up pouch in FIG. 3. In this embodiment, the retort package 60 is made entirely of retort packaging films described herein, using heat seals to form and close the package.

[078] In some embodiments of retort packages formed from a retort packaging film, the package has at least 90% polyolefin-based materials or at least 80% polyolefin-based materials, by weight. In some embodiments of retort packages formed from a retort packaging film, the package has at least 90% polypropylene-based materials or at least 80% polypropylene-based materials, by weight. In some embodiments of retort packages formed from a retort packaging film, the package has at least 90% polyolefin-based materials and at least 80% polypropylene-based materials, by weight.

SHELF-STABLE PACKAGED PRODUCT

[079] Described herein are retort packaging films and laminated polypropylene- based films suitable for retort packaging as well as the retort packages and shelfstable packaged products made therefrom, as shown in FIG. 3. Retort packaging film 10 is used to form the retort package 60 containing a product 111 to result in a shelf-stable packaged product after being exposed to retort conditions. As discussed previously, heat seals 110 are used to form the retort package and hermetically seal the shelf-stable packaged product.

[080] In some embodiments of the shelf-stable packaged product, the product in the retort package is a product that would be perishable were it not for the sterilization process it has undergone while being hermetically sealed within the retort packaging film. As used herein, the product may be a perishable food product, wherein the sterilization process (i.e. retort) enables the storage and preservation of the product at ambient conditions for many months or years. The product undergoes a sterilization process while being hermetically sealed within a package formed from a retort packaging film. Once sterilized, the retort package prevents the influx of oxygen (i.e. has high oxygen barrier properties) to help extend the shelf-life of the product.

[081] In some embodiments of the shelf-stable packaged product, the product in the retort package is a product that maintains sterility due to being sterilized while hermetically sealed inside the package.

EXAMPLES & DATA

[082] The properties and advantages of the retort packaging films disclosed herein are further demonstrated by the following examples and data.

[083] Several film structures that represent various embodiments of the multilayer barrier film are given in the non-exhaustive list below:

MDOPP I EVOH I PP// adh // PP sealant

MDOPP I tie I EVOH I tie / PP // adh // PP sealant

MDOPP / tie / EVOH / tie / EVOH / tie I PP // adh // PP sealant

[084] Hand laminates were made of three innovative films, each having in general the structure of: PP I EVOH / PP // adh // PP with the difference between the samples being multiple layers of EVOH for Example 2 or EVOH thickness for Example X. The exact structure and material details are outlined in Table 1 . Comparative Film Example 3 and 5 were constructed of alternate materials and reasonable substation of materials to evaluate the retort-shock recovery capabilities of the films and are used as a comparative example structures.

[085] Four example retort packaging films were assembled for testing. Details of Examples 1 through 3, 5, and X can be found in Table 1 below. [086] Each of Examples 1 through 3, 5, and X were hand laminates and included an interior polypropylene-based sealing film with a low seal-initiation temperature sealing layer(s), a barrier layer of EVOH, and multilayer propylene- based films with various orientations and layers positioned as exterior films, wherein the structures are constructed to primarily utilize 100% polypropylene- based materials.

[087] The films of Examples 1 through 3, 5 and X were bonded together using adhesive lamination. The adhesive used for these examples was a solvent based two-component polyurethane based system with aliphatic hardener, available from Henkel AG & Co. Examples 1 -2, 5 films were laminated so that the EVOH containing layers were in the interior structure of the outer film. Example 3 was constructed with the EVOH containing layer being embedded within the interior polypropylene-based sealing film.

[088] For each layer of the films of Examples 1 through 3, 5 and X, the amount of polyolefin-based material and/or polypropylene-based material is reported in Table 1 . The adhesives and inks were based on other polymers, thus containing 0% polyolefin and 0% polypropylene-based materials. The total composition of Examples 1 through 3, 5 and X, as it relates to polypropylene-based materials (PP), as a percentage by weight is reported in Table 1 .

[089] The stabilized oxygen transmission rate (OTR) is reported for each of

Examples 1 through 3, 5 and X along with the time to reach stabilization. The laminated films of Examples 1 through 3, 5 and X, were retorted within an autoclave at a temperature of 128°C for a period of 60 minutes. The retorted film samples were then quickly loaded onto a testing apparatus to monitor the oxygen transmission rate over time (during testing, if a sample was unable to be measured by the test equipment due to too high of an OTR, the sample was conditioned until a measurement was obtained). The test was run according to ASTM 1927-14, using conditions of 50% relative humidity on the “exterior” and 90% humidity on the “interior” and a temperature of 73°F (i.e. “exterior // interior” for abbreviation). Exterior and interior as described is related to testing positioning relative to the package, wherein the exterior is the exterior layer of polypropylene and interior is the polypropylene-based sealing film. Results of that testing are shown in FIG. 4. The data indicates that the films containing a machine direction oriented outer film (Film Examples 1 ,2 and X) reach a stabilized oxygen transmission rate quicker and generally have a lower stabilized oxygen barrier (lower oxygen transmission) after the film has recovered from retort shock than the comparative films. (Comparative Film Example 3, 5).

[090]

Table 1

MDOPP = machine direction oriented polypropylene film

⁺BOPP = Biaxially oriented polypropylene film

RETORT PACKAGING FILM EMBODIMENTS

(i) A recyclable retort packaging film comprising: an oriented exterior layer comprising a barrier layer, a sealing layer, wherein the retort packaging film has a total composition comprising at least 80% polyolefin-based polymers by weight, and wherein an oxygen transmission rate (OTR) of the retort packaging film is stabilized within 50 hours post retort conditions (128 °C, 60 min at 23°C/50-90%RH).

(ii) The retort packaging film according to any other embodiment wherein the exterior layer comprises a machine direction oriented multi-layer film.

(iii) The retort packaging film according to any other embodiment wherein the barrier layer is a buried layer within the exterior layer. (iv) The retort packaging film according to embodiment (iii) wherein the barrier layer is comprises ethylene vinyl alcohol copolymer.

(v) The retort packaging film according to embodiment (iv), wherein the barrier layer comprises at least two layers of ethylene vinyl alcohol copolymer.

(vi) The retort packaging film according to any other embodiment, wherein the sealing layer is a non-oriented polypropylene-based film.

(vii) A laminated recyclable polypropylene-based retort packaging film comprising: a first layer, the first layer being oriented and including a barrier, the first layer being an exterior layer, a second layer, the second layer being a sealing layer comprising a multilayer film, and wherein the laminated recyclable polypropylene-based retort packaging film comprises at least 88 % polypropylene-based polymers by weight, and wherein an oxygen transmission rate (OTR) of the retort packaging film is stabilized within 50 hours post retort conditions (128 °C, 60 min).

(viii) The retort packaging film according to embodiment (vii) wherein the first layer includes a first barrier layer and a second barrier layer.

(ix)The retort packaging film according to previous embodiments, wherein an adhesive layer is positioned between the first layer and the second layer. (x) The retort packaging film according to embodiment (viii) wherein the first layer is a multilayer film including a first tie layer positioned between the barrier layer and the oriented polypropylene-based layer.

(xi) The retort packaging film according to embodiment (x) wherein the first layer multilayer film includes a second tie layer positioned between the barrier layer and a second polypropylene layer.

(xii) The retort packaging film according to any other embodiment wherein the barrier layer is ethylene vinyl alcohol copolymer.

RETORT PACKAGE EMBODIMENTS

(I) A retort package formed from one or more of the retort packaging films according to any retort packaging film embodiment.

(II) A retort package comprising a retort packaging film wherein the oxygen transmission rate (OTR) of the recyclable retort packaging film post retort (128 °C, 60 min) conditions is stabilized within 50 hours to between a range of about 2.0 and 8.0 cm3/m2d at 23 °C, out//in 50/90 %RH according to ASTM-1927-14. Stated another way the stabilized OTR or recyclable film post retort has a stabilized OTR that is less than about 8.0 cm3/m2d at 23 °C, out/in 50/90 %RH according to ASTM-1927-14, preferably less than about 6.0 cm3/m2d at 23 °C, out/in 50/90 %RH according to ASTM-1927-14, preferably less than about 4.0 cm3/m2d at 23 °C, out/in 50/90 %RH according to ASTM-1927-14, or preferably less than about 2.0 cm3/m2d at 23 °C, out/in 50/90 %RH according to ASTM- 1927-14.

(Ill) The retort package formed from a retort packaging film the retort package including a polypropylene-based multilayer film comprising an exterior layer, the exterior layer being a coextruded multilayered oriented film having a first exterior layer of polypropylene, an interior barrier layer of ethylene vinyl alcohol copolymer, and a second layer of polypropylene, wherein the interior barrier layer is between the first exterior layer of the polypropylene and the second layer of polypropylene, an adhesive layer, an unoriented polypropylene based sealing layer positioned as an interior layer of the retort package, and wherein the oxygen transmission rate (OTR) of the polypropylene-based multilayer film post retort (128 °C, 60 min) conditions is stabilized within 50 hours to between a or recyclable film post retort has a stabilized OTR that is less than about 8.0 cm3/m2d at 23 °C, out/in 50/90 %RH according to ASTM-1927-14, preferably less than about 6.0 cm3/m2d at 23 °C, out/in 50/90 %RH according to ASTM-1927-14, preferably less than about 4.0 cm3/m2d at 23 °C, out/in 50/90 %RH according to ASTM-1927-14, or preferably less than about 2.0 cm3/m2d at 23 °C, out/in 50/90 %RH according to ASTM- 1927-14.

(IV) The retort package according to embodiment (III) wherein the exterior layer barrier layer comprises a pair of barrier layers, each barrier layer of the pair of barrier layers comprising ethylene vinyl alcohol copolymer.

(V) The retort package according to embodiment (III) or (IV) wherein the exterior layer comprises a tie layer positioned between the barrier layer or barrier layers and the exterior layer and the second layer of polypropylene. (VI) The retort package according to any previous retort package embodiment including a print layer, the print layer positioned on a second side of the second polypropylene and visible from an exterior of the package and through the exterior layer.

(VII) The retort package according to any previous retort package embodiment wherein the polypropylene-based multilayer film comprises at least 88 % polypropylene-based polymers by weight.

Claims

What is claimed:

1 . A recyclable packaging film for use in a retort process, the recyclable packaging film being a retort packaging film comprising: an oriented exterior layer comprising a barrier layer; a sealing layer; wherein the retort packaging film has a total composition comprising at least 80 % polypropylene-based polymers by weight; and wherein an oxygen transmission rate (OTR) of the retort packaging film is stabilized within 50 hours post retort conditions (128 °C, 60 min).

2. The retort packaging film according to claim 1 , wherein the exterior layer comprises a machine direction oriented multi-layer film.

3. The retort packaging film according to claim 1 , wherein the barrier layer is a buried layer within the exterior layer.

4. The retort packaging film according to claim 3, wherein the barrier layer comprises ethylene vinyl alcohol copolymer.

5. The retort packaging film according to claim 4, wherein the barrier layer comprises at least two layers of ethylene vinyl alcohol copolymer.

6. The retort packaging film according to claim 1 , wherein the sealing layer comprises a non-oriented polypropylene-based film.

7. A recyclable retort package formed of one or more of the retort packaging films according to claims 1 -6.

8. The recyclable retort package according to claim 7, wherein the oxygen transmission rate (OTR) of the recyclable retort packaging film post retort (128 °C, 60 min) conditions is stabilized within 50 hours to a range between of about 2.0 and 8.0 cm³/m²/day at 23°C, out/in 50/90 %RH according to ASTM-1927-14.

9. A laminated recyclable polypropylene-based film suitable for retort packaging, the laminated recyclable polypropylene-based film being a retort packaging film comprising: a first layer, the first layer being oriented and including a barrier, the first layer being an exterior layer; a second layer, the second layer being a sealing layer comprising a multilayer film, and wherein the laminated recyclable polypropylene-based retort packaging film comprises at least 88 % polypropylene-based polymers by weight; and wherein an oxygen transmission rate (OTR) of the retort packaging film is stabilized within 50 hours post retort conditions (128 °C, 60 min).

10. The laminated recyclable polypropylene-based retort packaging film as in claim 9, wherein the first layer includes a first barrier layer and a second barrier layer.

1 1 . The laminated recyclable polypropylene-based retort packaging film as in claim 9, wherein an adhesive layer is positioned between the first layer and the second layer.

12. The laminated recyclable polypropylene-based retort packaging film as in claim 11 , wherein the first layer is a multilayer film including a first tie layer positioned between the barrier layer an oriented polypropylene-based layer.

13. The laminated recyclable polypropylene-based retort packaging film as in claim 12, wherein the first layer multilayer film includes a second tie layer positioned between the barrier layer and a second polypropylene layer.

14. The laminated recyclable polypropylene-based retort packaging film as in claim 9, wherein the barrier layer comprises ethylene vinyl alcohol copolymer.

15. The laminated recyclable polypropylene-based retort packaging film as in claim 10, wherein the first and second barrier layer comprises ethylene vinyl alcohol copolymer.

16. A polypropylene-based recyclable retort package comprising a retort packaging film, the retort package comprising: a polypropylene-based multilayer film comprising: an exterior layer, the exterior layer being a coextruded multilayered oriented film having a first exterior layer of polypropylene, an interior barrier layer of ethylene vinyl alcohol copolymer, and a second layer of polypropylene, wherein the interior barrier layer is between the first exterior layer of the polypropylene and the second layer of polypropylene; an adhesive layer; an unoriented polypropylene based sealing layer positioned as an interior layer of the retort package; and wherein the oxygen transmission rate (OTR) of the polypropylene-based multilayer film post retort (128 °C, 60 min) conditions is stabilized within 50 hours to an OTR range between of about between 2.0 and 8.0 cm3/m²/day at 23 °C, out/in 50/90 %RH according to ASTM-1927-14.

17. The polypropylene-based recyclable retort package comprising the retort packaging film of claim 16, wherein the exterior layer barrier layer comprises a pair of barrier layers, each barrier layer of the pair of barrier layers comprising ethylene vinyl alcohol copolymer.

18. The polypropylene-based recyclable retort package comprising the retort packaging film of claims 16 and 17, wherein the exterior layer comprises a tie layer positioned between the barrier layer or barrier layers and the exterior layer and the second layer of polypropylene.

19. The polypropylene-based recyclable retort package of any of claims 16-18 comprising a print layer, the print layer positioned on a second side of the second polypropylene and visible from an exterior of the package and through the exterior layer.

20. The polypropylene-based recyclable retort package of any of claims 16-18, wherein the polypropylene-based multilayer film comprises at least 88 % polypropylene-based polymers by weight.