Cooking packaging film

Abstract

A retortable packaging film is disclosed. The retortable packaging film comprises a laminate, and the laminate comprises a BOPP (Biaxially-oriented Polypropylene) film and an MDOPP (Modified Dioctyl-Oriented Polypropylene) film. The retortable packaging film further includes a sealing layer disposed on the laminate. The sealing layer includes a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. The sealing layer has a melt flow index in the range of from 5 g / 10 minutes to 25 g / 10 minutes according to ASTM D1238 Program A condition 230 DEG C / 2.16 kg. The retortable packaging film further includes a total composition including at least 80% by weight of polypropylene.

Description

Technical Field

[0001] The present application generally relates to a retort packaging film, a hermetically sealed packaged food product including the retort packaging film, and a method of producing the retort packaging film. Background Art

[0002] Retortable packaging such as stand-up pouches are often made from multi-polymer laminates such as PET / OPA / PP (polyester / oriented polyamide / polypropylene) and PET / ALU / PP (polyester / aluminum / polypropylene). However, due to the presence of materials such as PET, ALU and OPA, such multi-polymer laminates may not meet certain recycling guidelines (e.g., CEFLEX).

[0003] In order to comply with recycling guidelines, single polymer laminates (e.g., PE or PP based laminates) can be used to prepare retortable packaging. However, preparing retortable packaging from single polymer laminates may present several challenges. For example, the retortable packaging may need to have high seal strength and be robust enough for retort processing while exhibiting straight tear properties in one direction to facilitate opening of the retortable packaging.

[0004] Conventionally, straight tear properties are usually imparted to multi-polymer laminates by a scoring process (e.g., laser scoring). However, the scores made by such scoring processes may be visible features that may adversely affect the aesthetic appearance of a retortable package made from the multi-polymer laminate. Scoring may also not be feasible for a single polymer laminate. Additionally, a single polymer laminate may need to be heat sealed at a relatively low temperature (e.g., 120° C. to 140° C.) so that the single polymer laminate is not damaged (e.g., melted, warped, or destroyed).

[0005] Therefore, there is a need for a retort packaging film that includes high levels of polyolefin (i.e., greater than 80 wt. % or 90 wt. %) to meet recycling guidelines, has high seal strength and is robust enough for retort processing, and exhibits straight tear properties in one direction to facilitate opening of the retort package without the need for visible features (e.g., scores) that may detract from the aesthetic appearance of the retort package. Summary of the invention

[0006] Retortable packaging films have been developed. The retortable packaging films include a single polymer laminate and can therefore comply with certain recycling guidelines. In addition, the single polymer laminate can provide the retortable packaging films with sufficient robustness to withstand retorting and other high temperature sterilization processes.

[0007] The retortable packaging film further comprises a sealing layer disposed on the monopolymer laminate. The sealing layer can provide high sealing strength at a low sealing initiation temperature. In other words, the retortable packaging film can be sealed at a relatively low temperature (e.g., 120° C. to 140° C.) and provide a high sealing strength (e.g., greater than 10 N / 15 mm) that may be necessary for a retort process. The monopolymer laminate can be elastic and will not be damaged by heat sealing by having a low sealing initiation temperature.

[0008] The sealant layer may be suitable for extrusion coating onto the monopolymer laminate and may not be suitable for blown film extrusion and cast film extrusion. Specifically, the sealant layer may be designed for and may be suitable for extrusion coating. The sealant layer may not be ideal for blown film extrusion and cast film extrusion. The melt flow index of the sealant layer designed for and may be suitable for blown film extrusion is generally less than 5 g / 10 min and is not suitable for the sealant layer of the present invention. The melt flow index of the sealant layer designed for and may be suitable for cast film extrusion is generally less than 10 g / 10 min or less than 7 g / 10 min and is not suitable for the sealant layer of the present invention.

[0009] The retortable packaging film can exhibit straight tear properties (e.g., along the machine direction). The straight tear properties can be provided by the orientation of one or more films of the monopolymer laminate. As a result, the retortable packaging film can exhibit the straight tear properties without using notches or any visible features. Therefore, any graphics or other appearance features that can be printed on the retortable packaging made from the retortable packaging film can be unaffected by such notches or visible features. This can improve the aesthetic appearance of the retortable packaging.

[0010] The straight tear property may facilitate the opening of the retort packaging made from the retort packaging film. Advantageously, the sealing layer may not adversely affect the straight tear property of the retort packaging film while having a low sealing initiation temperature.

[0011] The retort packaging film may comply with recycling guidelines, may have high seal strength, and may be robust enough for retort processing, and may exhibit straight tear properties in one direction (eg, machine direction) to facilitate opening of a retort package made from the retort packaging film.

[0012] One embodiment of the present disclosure is a retortable packaging film. The retortable packaging film comprises a laminate, the laminate comprising a biaxially oriented polypropylene (BOPP) film and a machine direction oriented polypropylene (MDOPP) film. The retortable packaging film further comprises a sealing layer, the sealing layer being disposed on the laminate. The sealing layer comprises a blend, the blend comprising a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of a low density polyethylene (LDPE) and a medium density polyethylene (MDPE). According to ASTM D1238 procedure A condition 230°C / 2.16kg, the melt flow index of the sealing layer is in the range of 5 g / 10 min to 25 g / 10 min. The retortable packaging film further comprises a total composition, the total composition comprising at least 80 wt% of polypropylene.

[0013] The sealing layer may provide high sealing strength at a low sealing initiation temperature. In other words, the retortable packaging film may be sealed at a relatively low temperature (e.g., 120° C. to 140° C.) and provide high sealing strength (e.g., greater than 10 N / 15 mm) that may be necessary for a retort process. The laminate including the BOPP film and the MDOPP film may not be damaged by heat sealing at the relatively low temperature.

[0014] The sealing layer may be suitable for extrusion coating and may not be suitable for blown film extrusion and cast film extrusion. Specifically, the melt flow index of the sealing layer (i.e., between 5 g / 10 min and 25 g / 10 min at 230°C / 2.16 kg) may make the sealing layer suitable for extrusion coating. The sealing layer may not be ideal for blown film extrusion and cast film extrusion. The melt flow index of the sealing layer designed for and suitable for blown film extrusion is generally less than 5 g / 10 min and is not suitable for the sealing layer of the present invention. The melt flow index of the sealing layer designed for and suitable for cast film extrusion is generally less than 10 g / 10 min or less than 7 g / 10 min and is not suitable for the sealing layer of the present invention.

[0015] The retort packaging film may exhibit straight tear properties (e.g., along the machine direction). The straight tear properties may be provided by the MDOPP film of the laminate. Advantageously, the retort packaging film may exhibit the straight tear properties without the use of notches or any visible features. Thus, any graphics or other appearance features that may be printed on a retort package made from the retort packaging film may not be disrupted by such notches or visible features. This may improve the aesthetic appearance of the retort package.

[0016] The straight tear property may facilitate the opening of the retort packaging made from the retort packaging film. Advantageously, the sealing layer may not adversely affect the straight tear property of the retort packaging film while having a low sealing initiation temperature.

[0017] The retortable packaging film can meet the recycling guidelines because the total composition of the retortable packaging film comprises at least 80% by weight of polypropylene. Further, the retortable packaging film can be robust enough for retorting. Due to the sealing layer, the retortable packaging film can have high sealing strength. Advantageously, the sealing layer can provide the high sealing strength at a low sealing starting temperature so that the laminate can not melt, warp or be damaged. Further, the retortable packaging film can show straight tear properties in one direction (e.g., machine direction) to promote the opening of the retortable packaging made of the retortable packaging film.

[0018] In some embodiments, the blend of the sealant layer comprises 4 wt% to 50 wt% of the long chain branched polyethylene and 50 wt% to 90 wt% of the polypropylene terpolymer.

[0019] In some embodiments, the polypropylene terpolymer has a melting temperature above 130°C.

[0020] In some embodiments, the seal initiation temperature of the seal layer is less than 140°C as measured using ASTM F88 Technique A.

[0021] In some embodiments, the melt flow index of the sealant layer is between 5 g / 10 min and 15 g / 10 min according to ASTM D1238, Procedure A, Condition 230° C. / 2.16 kg.

[0022] In some embodiments, the sealing layer is non-oriented. The non-oriented sealing layer may allow the sealing layer to have a low sealing initiation temperature.

[0023] In some embodiments, the sealant layer is extrusion coated onto the laminate. The melt flow index of the sealant layer may make the sealant layer suitable for extrusion coating. The melt flow index of the sealant layer may make the sealant layer unsuitable for blown film extrusion and cast film extrusion.

[0024] In some embodiments, the laminate further comprises a barrier layer attached to the BOPP film or the MDOPP film. The barrier layer can impart various barrier properties, such as moisture barrier properties, gas barrier properties and / or odor barrier properties, to the retortable packaging film.

[0025] In some embodiments, the barrier layer includes one of a metal layer or an oxide coating deposited on a surface of the BOPP film or the MDOPP film.

[0026] In some embodiments, the barrier layer comprises a polymeric barrier material.

[0027] In some embodiments, the total composition includes at least 90 wt% polypropylene.

[0028] In some embodiments, the total composition includes less than 20 weight percent non-polyolefin materials.

[0029] In some embodiments, the total composition includes less than 10 weight percent non-polyolefin material.

[0030] In some embodiments, the MDOPP film is located on an outer surface of the retortable packaging film.

[0031] In some embodiments, the BOPP film is located on the outer surface of the retortable packaging film.

[0032] Another embodiment of the present disclosure is an airtight packaged food product. The airtight packaged food product includes the retort packaging film. The airtight packaged food product can be recycling compatible and can have the straight tear property of the retort packaging film. As a result, the airtight packaged food product can be easily opened when needed.

[0033] Another embodiment of the present disclosure is a method of producing a retortable packaging film. The method includes laminating a BOPP film to an MDOPP film to form a pre-laminate. The method further includes extrusion coating a sealant layer onto the pre-laminate. The sealant layer includes a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. The melt flow index of the sealant layer is between 5 g / 10 min and 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg.

[0034] Another embodiment of the present disclosure is a method of producing a retortable packaging film. The method includes extruding a film and orienting the film in a machine direction to produce an MDOPP film. The method further includes extrusion coating a sealant layer onto the MDOPP film. The method further includes applying a barrier coating to a BOPP film. The method further includes adhesive laminating the MDOPP film and the BOPP film. The sealant layer includes a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. The melt flow index of the sealant layer is between 5 g / 10 min and 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16kg.

[0035] Several aspects of the subject matter can be embodied individually or together. These aspects can be used alone or in combination with other aspects of the subject matter described herein, and the description of these aspects together is not intended to exclude the use of these aspects alone or to require such aspects alone or in different combinations. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present disclosure may be more fully understood by considering the following detailed description of various embodiments of the present disclosure in conjunction with the accompanying drawings, in which:

[0037] Figure 1 is a schematic cross-sectional view of a retortable packaging film according to an embodiment of the present disclosure;

[0038] Figure 2 is a schematic cross-sectional view of a retortable packaging film according to another embodiment of the present disclosure;

[0039] Figure 3 is a schematic cross-sectional view of a retortable packaging film according to another embodiment of the present disclosure;

[0040] Figure 4 is a schematic cross-sectional view of a retortable packaging film according to another embodiment of the present disclosure;

[0041] Figure 5 is a schematic cross-sectional view of a retortable packaging film according to another embodiment of the present disclosure;

[0042] Figure 6 is a schematic front view of a hermetically sealed packaged food product according to an embodiment of the present disclosure;

[0043] Figure 7 is a flow chart depicting various steps of a method for producing a retortable packaging film according to an embodiment of the present disclosure; and

[0044] Figure 8is a flow chart depicting various steps of a method of producing a retortable packaging film according to another embodiment of the present disclosure.

[0045] The drawings are not necessarily drawn to scale. The same numbers used in the drawings refer to the same components. However, it should be understood that the use of a number to refer to a component in a given figure is not intended to limit the component labeled with the same number in another figure. DETAILED DESCRIPTION

[0046] A retortable packaging film has been developed. The retortable packaging film comprises a laminate comprising a BOPP film and an MDOPP film. The retortable packaging film further comprises a sealing layer disposed on the laminate. The sealing layer comprises a blend comprising a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. The melt flow index of the sealing layer is between 5 g / 10 min and 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16kg. The retortable packaging film further comprises a total composition comprising at least 80 wt% polypropylene.

[0047] The sealing layer can provide high sealing strength at a low sealing initiation temperature. In other words, the retortable packaging film can be sealed at a relatively low temperature (e.g., 120° C. to 140° C.) and provide a high sealing strength (e.g., greater than 10N / 15mm) that may be necessary for a retort process. The laminate including the BOPP film and the MDOPP film may not be damaged by heat sealing at a relatively low temperature. The laminate may be elastic and not damaged by heat sealing because the heat seal has a sealing layer with a low sealing initiation temperature.

[0048] The sealing layer may be suitable for extrusion coating and may not be suitable for blown film extrusion and cast film extrusion. Specifically, the melt flow index of the sealing layer (i.e., between 5 g / 10 min and 25 g / 10 min at 230°C / 2.16kg) may make the sealing layer suitable for extrusion coating and may make the sealing layer unsuitable for blown film extrusion processing. The melt flow index of the sealing layer may further make the sealing layer unsuitable for cast film extrusion processing. In other words, the sealing layer may not be ideal for blown film extrusion and cast film extrusion. The melt flow index of the sealing layer designed for and suitable for blown film extrusion is generally less than 5 g / 10 min and is not suitable for the sealing layer of the present invention. The melt flow index of the sealing layer designed for and suitable for cast film extrusion is generally less than 10 g / 10 min or less than 7 g / 10 min and is not suitable for the sealing layer of the present invention.

[0049] The retort packaging film may exhibit straight tear properties (e.g., along the machine direction). The straight tear properties may be provided by the MDOPP film of the laminate. Advantageously, the retort packaging film may exhibit the straight tear properties without including notches or any other visible features. Thus, any graphics or other appearance features that may be printed on a retort package made from the retort packaging film may not be damaged by such notches or visible features. This may improve the aesthetic appearance of the retort package.

[0050] The straight tear property may facilitate the opening of a retort package made from the retort packaging film. Advantageously, the sealing layer may not adversely affect the straight tear property of the retort packaging film while having a low sealing initiation temperature.

[0051] The retortable packaging film can meet the recycling guidelines because the total composition of the retortable packaging film comprises at least 80% by weight of polypropylene. Further, the retortable packaging film can be robust enough for retorting. Due to the sealing layer, the retortable packaging film can have high sealing strength. Advantageously, the sealing layer can provide the high sealing strength at a low sealing starting temperature so that the laminate can not melt, warp or be damaged. Further, the retortable packaging film can show straight tear properties in one direction (e.g., machine direction) to promote the opening of the retortable packaging made of the retortable packaging film.

[0052] As used herein, the terms "first" and "second" are used as identifiers. Therefore, such terms should not be interpreted as limitations on the present disclosure. When used in conjunction with features or elements, the terms "first" and "second" can be interchangeable in embodiments of the present disclosure.

[0053] As used herein, the term "film" is a material with a very high ratio of length or width to thickness. The film has two main surfaces defined by length and width. The film generally has good flexibility and can be used for various applications. The film can also have a suitable thickness and / or material composition so that it is flexible, semi-rigid or rigid. The film can be described as a single layer or a multilayer.

[0054] As used herein, the terms "inner" and "outer" refer to the major surfaces of a film or layer.

[0055] As used herein, the term "retort process" refers to a process in which food, medical or other items packaged in a flexible package can be heated to a high temperature (e.g., 104° C. to 149° C. or 120° C. to 135° C.) under high pressure (e.g., in the presence of water, steam or pressurized steam) for an extended period of time, such as 10 to 60 minutes. The term "retort process" may also include other high temperature sterilization processes, such as hot filling.

[0056] As used herein, the term "retort package" refers to a package that is hermetically sealed and capable of maintaining its hermetically sealed state during the retort process. For example, the retort package can maintain its hermetically sealed state during the cooking of the food composition hermetically sealed in the retort package. The term "retort package film" refers to a film that can be used to form a retort package.

[0057] As used herein, the term "laminate" refers to a product made by bonding two or more films or other materials together. Laminates can be prepared by any lamination process. For example, lamination can be achieved by bonding films together using an adhesive, bonding using heat and pressure, and even by diffusion coating and extrusion coating. The term "laminate" also includes coextruded multilayer films that include one or more adhesive layers.

[0058] As used herein, the term "pre-laminate" refers to a laminate to which one or more polymeric layers may be coated, adhered or otherwise attached.

[0059] As used herein, the term "BOPP film" refers to a biaxially oriented polypropylene film. A BOPP film is a polypropylene film that has been subjected to a stretching process in the machine direction and the transverse direction.

[0060] As used herein, the term "MDOPP film" is a machine direction oriented polypropylene film. MDOPP film is a polypropylene film that has been subjected to a stretching process in the machine direction.

[0061] As used herein, the term "sealing layer" refers to a layer of a film, sheet, etc. that is involved in sealing the film, sheet, etc. to itself and / or another layer of the same or another film, sheet, etc.

[0062] As used herein, the term "terpolymer" refers to a copolymer produced by three different monomers. The term "polypropylene terpolymer" refers to a polypropylene molecular chain modified with two additional comonomers during the polymerization process. Examples of the two additional comonomers may include ethylene and / or C4-C16 α-olefins, ethylene and / or C4-C8 α-olefins, and ethylene and butene.

[0063] As used herein, the term "low density polyethylene" or "LDPE" refers to polyethylene having a density typically between 0.910 g / cm 3 and 0.930g / cm 3 Branched homopolymers between 1,2-dimethyl-1,4-dimethoxy ...

[0064] As used herein, the term "medium density polyethylene" or "MDPE" refers to polyethylene having a density generally between 0.928 g / cm 3 and 0.940g / cm 3 Medium density polyethylene includes linear medium density polyethylene (LMDPE).

[0065] As used herein, the term "melt flow index" or "MFI" refers to a measure of the ease with which a melt of a polymer flows. The melt flow index means the amount of resin in grams that can be forced through a plastometer or rheometer (as defined in ASTM D1238) in ten minutes at a given temperature and pressure.

[0066] As used herein, the term "melting temperature" or "Tm" refers to the temperature at which solid and liquid phases of a material can coexist in equilibrium.

[0067] As used herein, the term "seal initiation temperature" refers to a sealing temperature at which a seal strength of about 5 N / 15 mm is achieved. The seal initiation temperature may be evaluated using ASTM F88.

[0068] As used herein, the term "oriented" refers to films, sheets, webs, etc. that are elongated in at least one of the machine direction and the transverse direction. The term "non-oriented" or "unoriented" refers to films, sheets, webs, etc. that are substantially free of orientation after formation.

[0069] As used herein, the term "extrusion coating" refers to a process whereby a coating material in a melt state is applied to at least a portion of a substrate, optionally under pressure and / or at elevated temperature.

[0070] As used herein, the term "barrier layer" refers to a layer of a film including any material that controls the permeable elements of the film. The barrier layer may provide, for example, an oxygen barrier, a moisture barrier, a chemical barrier, a thermal barrier, and / or an odor barrier.

[0071] As used herein, the term "adhesive layer" refers to a layer having the primary function of bonding two adjacent layers together. The adhesive layer can be positioned between two layers of a multilayer film, with the two layers maintained in a position relative to each other and preventing undesirable delamination. Unless otherwise indicated, the adhesive layer can have any suitable composition, which provides the bonding of one or more surfaces in contact with the adhesive layer material of the desired level. The adhesive layer can alternatively be referred to as a "bonding layer".

[0072] As used herein, the term "polyethylene" refers to a homopolymer or copolymer having at least one ethylene monomer bond within the repeating backbone of the polymer. The ethylene bond can be represented by the general formula: [CH2—CH2] nThe polyethylene may be formed by any method known to those skilled in the art.

[0073] As used herein, the term "polyolefin" refers to a polyolefin having the general formula (CH2CHR) n The term "non-polyolefin material" or "non-olefin material" refers to any material that is not a polyolefin. For example, the non-polyolefin material may include polyamide, polyester, styrene, polyurethane, etc.

[0074] As used herein, the term "monopolymer laminate" refers to a laminate comprising an overall composition comprising a substantial amount of a single polymer type (eg, greater than 80%, 90% or 95% by total weight of the laminate).

[0075] As used herein, the term "straight tear property" refers to a property of a film, sheet, roll, etc. that allows the film, sheet, roll, etc. to be easily torn in a substantially straight line.

[0076] Figure 1 A schematic cross-sectional view of a retort packaging film 10 according to an embodiment of the present disclosure is shown.

[0077] The retortable packaging film 10 includes a laminate 110. The laminate 110 includes an MDOPP film 112 and a BOPP film 114. The laminate 110 may be formed by any suitable lamination method, such as coextrusion, adhesive lamination, and the like.

[0078] exist Figure 1 In the illustrated embodiment, the laminate 110 further includes an adhesive layer 115 disposed between the MDOPP film 112 and the BOPP film 114. The adhesive layer 115 can bond the BOPP film 114 to the MDOPP film 112. The adhesive layer 115 can include any suitable adhesive, such as a water-soluble adhesive, a radiation-cured or heat-cured adhesive, a hot melt adhesive, and a pressure-sensitive adhesive. Examples of these aforementioned adhesive materials include polyacrylates, acrylic emulsions, polyurethanes, polyamides, reaction products of polyamides with vegetable oil acids, epoxy resins, ethyleneamines, polysiloxanes, silicone rubbers, polyalkylene glycols, polyesters, sulfopolyesters, and the like. It should be noted that the adhesive layer 115 is optional and can be omitted from the laminate 110, for example, if the laminate 110 is formed using a lamination method that does not utilize an adhesive.

[0079] The retortable packaging film 10 further comprises a sealing layer 120 disposed on the laminate 110. The sealing layer 120 comprises a blend comprising a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. In some embodiments, the blend of the sealing layer 120 comprises 4 wt % to 50 wt % of the long chain branched polyethylene and 50 wt % to 90 wt % of the polypropylene terpolymer. In some embodiments, the melting temperature of the polypropylene terpolymer is higher than 130°C.

[0080] The melt flow index of the sealing layer 120 is in the range of 5 g / 10 min to 25 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg. In some embodiments, the melt flow index of the sealing layer 120 is in the range of 5 g / 10 min to 15 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg. In some embodiments, the melt flow index of the sealing layer 120 is in the range of 7 g / 10 min to 25 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg. In some embodiments, the melt flow index of the sealing layer 120 is in the range of 10 g / 10 min to 25 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg. In some embodiments, the melt flow index of the sealing layer 120 is in the range of 7 g / 10 min to 15 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg. In some embodiments, the melt flow index of the sealing layer 120 is in the range of 10 g / 10 min to 15 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg.

[0081] The melt flow index of the sealant layer 120 may make it suitable for some processes and may make it unsuitable for other processes. Table 1 provides the melt flow index range of typical polyethylene grades by process. The melt flow index ranges in Table 1 are taken from "The Science and Technology of Flexible Packaging: Multilayer Films from Resin and Process to End Use" by Barry A. Morrison.

[0082] Table 1: Melt flow index ranges for typical polyethylene grades by process

[0083]

[0084] As depicted in Table 1, the melt flow index of the sealing layer 120 (between 5 g / 10 min and 25 g / 10 min at 230° C. / 2.16 kg) can make the sealing layer 120 suitable for extrusion coating onto the laminate 110. Therefore, in some embodiments, the sealing layer 120 is extrusion coated onto the laminate 110. Further, such a melt flow index of the sealing layer 120 can make the sealing layer 120 unsuitable for blown film extrusion and cast film extrusion. The melt flow index of the sealing layer designed and suitable for blown film extrusion is generally lower than 5 g / 10 min and is not suitable for use as the sealing layer 120. The melt flow index of the sealing layer designed and suitable for cast film extrusion is generally lower than 10 g / 10 min or lower than 7 g / 10 min and is not suitable for use as the sealing layer 120.

[0085] The sealing layer 120 can provide a high seal strength (e.g., a seal strength greater than 5 Newtons / 15 millimeters or greater), which may be important for retort applications. In addition, the sealing layer 120 can have a low seal initiation temperature. For example, the seal initiation temperature of the sealing layer 120 can be in the range of 100°C to 140°C or in the range of 120°C to 140°C. In some embodiments, the seal initiation temperature of the sealing layer 120 is less than 140°C, as measured using ASTM F88 technique A. In some embodiments, the sealing layer 120 is unoriented. The unoriented sealing layer 120 can allow the sealing layer 120 to have a low seal initiation temperature.

[0086] The BOPP film 114 may provide sufficient rigidity to the retortable packaging film 10 for packaging applications. However, the laminate 110 including the MDOPP film 112 and the BOPP film 114 may not have high heat resistance. Therefore, the laminate 110 may be prone to defects when subjected to high temperatures during heat sealing.

[0087] The sealing layer 120 may enable the retort packaging film 10 to be heat-sealed at low temperatures (eg, at 125° C.) so that the laminate 110 may not melt, warp, or break.

[0088] The retortable packaging film 10 can show a straight tearing property (e.g., along the machine direction). The straight tearing property can be provided by the MDOPP film 112 of the laminate 110. Therefore, the retortable packaging formed by the retortable packaging film 10 can also show a straight tearing property to facilitate the opening of the retortable packaging. Advantageously, the retortable packaging film 10 can show a straight tearing property without using a notch or any visible feature. Therefore, any graphics or other appearance features that can be printed on the retortable packaging can be free from the destruction of such notches or visible features. This can improve the aesthetic appearance of the retortable packaging.

[0089] The retortable packaging film 10 comprises a total composition comprising at least 80% by weight of polypropylene. Therefore, in some embodiments, the total composition comprises less than 20% by weight of non-polyolefin materials. In some embodiments, the total composition comprises at least 90% by weight of polypropylene. Therefore, in some embodiments, the total composition comprises less than 10% by weight of non-polyolefin materials.

[0090] exist Figure 1 In the illustrated embodiment, the BOPP film 114 is located on the outer surface 11 of the retortable packaging film 10. In other words, the BOPP film 114 defines the outer surface 11 of the retortable packaging film 10. The outer surface 11 may be opposite to the sealing layer 120. The outer surface 11 may form the outer surface of a package formed using the retortable packaging film 10. In addition, Figure 1 In the illustrated embodiment, the sealing layer 120 is disposed on the MDOPP film 112. The sealing layer 120 may be extrusion coated on the MDOPP film 112.

[0091] Figure 2 FIG. 2 shows a schematic cross-sectional view of a retort packaging film 20 according to another embodiment of the present disclosure. The retort packaging film 20 is similar to Figure 1 The retort packaging film 10 of the present invention is shown in FIG. 1 , wherein similar elements are represented by similar reference characters. However, compared with the retort packaging film 10, the retort packaging film 20 has a different configuration of the laminate 110.

[0092] Specifically, in Figure 2 In the illustrated embodiment, the MDOPP film 112 is located on the outer surface 21 of the retortable packaging film 20. In other words, the MDOPP film 112 defines the outer surface 21 of the retortable packaging film 20. The outer surface 21 may be opposite to the sealing layer 120. The outer surface 21 may form the outer surface of a package formed using the retortable packaging film 20. In addition, Figure 2 In the illustrated embodiment, the sealant layer 120 is disposed on the BOPP film 114. The sealant layer 120 may be extrusion coated on the BOPP film 114.

[0093] Figure 3 FIG. 2 shows a schematic cross-sectional view of a retort packaging film 30 according to another embodiment of the present disclosure. The retort packaging film 30 is similar to Figure 1 The retort packaging film 10 of the present invention is shown in FIG. 1 , wherein similar elements are represented by similar reference characters. However, compared with the retort packaging film 10, the retort packaging film 30 has a different configuration of the laminate 110.

[0094] In some embodiments, the laminate 110 further includes a barrier layer 116 attached to the MDOPP film 112 or the BOPP film 114. It should be noted that the barrier layer 116 is optional and can be omitted from the laminate 110 based on the desired application properties. Figure 3 In the illustrated embodiment, the barrier layer 116 is attached to the BOPP film 114 .

[0095] The barrier layer 116 may provide desired barrier properties to the retort packaging film 30. For example, the barrier layer 116 may provide the retort packaging film 30 with gas (eg, oxygen) barrier properties, moisture barrier properties, and / or odor barrier properties.

[0096] In some embodiments, the barrier layer 116 includes a metal layer or an oxide coating deposited on the surface of the MDOPP film 112 or the BOPP film 114. Figure 3 In the illustrated embodiment, a metal layer or oxide coating is deposited on the surface of the BOPP film 114. The metal layer of the barrier layer 116 may include, for example, a foil (e.g., an aluminum foil). The oxide coating of the barrier layer 116 may include, for example, aluminum oxide, silicon oxide, metallized polyethylene terephthalate, and the like.

[0097] In some embodiments, barrier layer 116 includes a polymeric barrier material. The polymeric barrier material may include, but is not limited to, ethylene-vinyl alcohol (EVOH) copolymers; polyvinyl alcohol (PVOH) copolymers; poly(vinyl chloride); polyvinylidene polymers and copolymers including polyvinylidene chloride; polyamides including amorphous polyamides; acrylonitrile polymers including acrylonitrile-methyl acrylate copolymers; polyurethane engineered plastics; poly(methylpentene) resins; ethylene-carbon monoxide copolymers; liquid crystal polymers; polyesters such as polyethylene terephthalate; polyimides including polyetherimides and polyacrylimides; and other such polymeric materials known to have relatively low gas transmission rates. Blends and grafts of these aforementioned materials, such as combinations of polyimides and crystalline polymers such as liquid crystal polymers, polyamides and polyethylene terephthalate, and combinations of polyamides and styrenes may also be suitable for use as polymeric barrier materials.

[0098] exist Figure 3 In the illustrated embodiment of the present invention, the BOPP film 114 is located on the outer surface 31 of the retortable packaging film 30. In other words, the BOPP film 114 defines the outer surface 31 of the retortable packaging film 30. The outer surface 31 may be opposite to the sealing layer 120. The outer surface 31 may form the outer surface of a package formed using the retortable packaging film 30.

[0099] exist Figure 3In the illustrated embodiment, the adhesive layer 115 is disposed between the MDOPP film 112 and the barrier layer 116. Figure 3 In the illustrated embodiment, the sealing layer 120 is disposed on the MDOPP film 112. The sealing layer 120 may be extrusion coated on the MDOPP film 112.

[0100] Figure 4 FIG. 4 is a schematic cross-sectional view of a retort packaging film 40 according to another embodiment of the present disclosure. Figure 3 The retort packaging film 30 of the present invention is shown in FIG. 1 , wherein similar elements are represented by similar reference characters. However, compared with the retort packaging film 30, the retort packaging film 40 has a different configuration of the laminate 110.

[0101] Specifically, in Figure 4 In the illustrated embodiment, the MDOPP film 112 is located on the outer surface 41 of the retortable packaging film 40. In other words, the MDOPP film 112 defines the outer surface 41 of the retortable packaging film 40. The outer surface 41 may be opposite to the sealing layer 120. The outer surface 41 may form the outer surface of a package formed using the retortable packaging film 40. In addition, Figure 4 In the illustrated embodiment, the barrier layer 116 is attached to the MDOPP film 112 .

[0102] exist Figure 4 In the illustrated embodiment, the adhesive layer 115 is disposed between the BOPP film 114 and the barrier layer 116. Figure 4 In the illustrated embodiment, the sealant layer 120 is disposed on the BOPP film 114. The sealant layer 120 may be extrusion coated on the BOPP film 114.

[0103] Figure 5 FIG. 4 shows a schematic cross-sectional view of a retort packaging film 50 according to another embodiment of the present disclosure. Figure 4 The retort packaging film 40 of the present invention is shown in FIG. 1 , wherein similar elements are represented by similar reference characters. However, compared with the retort packaging film 40, the retort packaging film 50 has a different configuration of the laminate 110.

[0104] Specifically, in Figure 5 In the illustrated embodiment, the barrier layer 116 is disposed on the BOPP film 114 opposite the sealing layer 120. Figure 5 In the illustrated embodiment, adhesive layer 115 is disposed between MDOPP film 112 and barrier layer 116 .

[0105] exist Figure 5In the illustrated embodiment, the MDOPP film 112 is located on the outer surface 51 of the retort packaging film 50. In other words, the MDOPP film 112 defines the outer surface 51 of the retort packaging film 50. The outer surface 51 may be opposite to the sealing layer 120. The outer surface 51 may form the outer surface of a package formed using the retort packaging film 50.

[0106] Figure 6 A schematic front view of a hermetically sealed packaged food product 200 is shown in accordance with an embodiment of the present disclosure.

[0107] The hermetically sealed packaged food product 200 may include a retort package 210 and a food product (not shown) packaged within the retort package 210. Figure 6 In the illustrated embodiment, the retortable package 210 is a stand-up pouch. However, it should be noted that the retortable package 210 may be any suitable type of flexible package.

[0108] exist Figure 6 In the illustrated embodiment, the hermetically sealed packaged food product 200 comprises Figure 1 Specifically, the retort packaging 210 may include the retort packaging film 10. In other words, the retort packaging 210 may be made of the retort packaging film 10. In some other embodiments, the hermetically sealed packaged food product 200 may include Figure 2 Retort packaging film 20, Figure 3 Retort packaging film 30, Figure 3 Retort packaging film 30, Figure 4 Retort packaging film 40 or Figure 5 The retortable packaging film 50.

[0109] refer to Figure 1 and 6 , the retort packaging film 10 can be hermetically heat sealed to form the retort packaging 210. As a result, the retort packaging 210 can be suitable for undergoing a retort process. Advantageously, the retort packaging 210 can exhibit a straight tear property along an opening direction 220. The opening direction 220 can correspond to the machine direction of the MDOPP film 112 of the retort packaging film 10. As a result, the retort packaging 210 can be easily torn along the opening direction 220 to access the food product packaged therein. Advantageously, an implement such as a pair of scissors may not be required to open the retort packaging 210.

[0110] Figure 7 A flowchart depicting the various steps of a method 300 for producing a retortable packaging film according to an embodiment of the present disclosure is shown. For example, the method 300 can be used to produce Figure 1 Retort packaging film 10, Figure 2Retort packaging film 20, Figure 3 Retort packaging film 30, Figure 4 Retort packaging film 40 or Figure 5 The retortable packaging film 50.

[0111] At step 310, method 300 includes laminating a BOPP film to an MDOPP film to form a pre-laminate. Figure 1 and 7 For example, method 300 may include laminating MDOPP film 112 to BOPP film 114 to form laminate 110. The pre-laminate may have any suitable configuration, as described above with reference to Figure 1-5 The configuration of laminate 110 is described.

[0112] At step 320, method 300 further includes extrusion coating a sealing layer onto the pre-laminate. The sealing layer includes a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. The melt flow index of the sealing layer is between 5 g / 10 min and 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg. Reference Figure 1 and 7 For example, the method 300 may include extrusion coating the sealing layer 120 onto the laminate 110. The sealing layer 120 may include a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. Further, the melt flow index of the sealing layer 120 may be between 5 g / 10 min and 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg.

[0113] The method 300 may allow for the production of a retortable packaging film in a simple and economical manner.

[0114] Figure 8 A flowchart depicting the various steps of a method 400 for producing a retortable packaging film according to an embodiment of the present disclosure is shown. For example, the method 400 can be used to produce Figure 3 The retortable packaging film 30.

[0115] At step 410, method 400 includes extruding a film and orienting the film in a machine direction to produce an MDOPP film. Figure 3 and 8 For example, the method 400 may include extruding a film and machine direction orienting the film to produce the MDOPP film 112 .

[0116] At step 420, method 400 further includes extrusion coating a sealing layer onto the MDOPP film. Figure 3 and 8 For example, the method 400 may include extrusion coating the sealing layer 120 onto the MDOPP film 112 .

[0117] At step 430, method 400 further includes applying a barrier coating to the BOPP film. Figure 3 and 8 For example, method 400 may include applying barrier layer 116 to BOPP film 114 .

[0118] At step 440, method 400 further includes adhesive laminating the MDOPP film and the BOPP film. Figure 3 and 8 , for example, the method 400 may include adhesive laminating the MDOPP film 112 and the BOPP film 114 .

[0119] The sealing layer comprises a blend comprising a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. The melt flow index of the sealing layer is between 5 g / 10 min and 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg. Figure 3 and 8 For example, the sealing layer 120 may include a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE. Further, the melt flow index of the sealing layer 120 may be between 5 g / 10 min and 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg.

[0120] The method 400 may allow for the production of retortable packaging films in a simple and economical manner.

[0121] Examples

[0122] In the following examples, the following test scenario was used.

[0123] • Melt Flow Index—Units: grams / 10 minutes, ASTM D1238, tested at 230°C using 2.16 kg, unless otherwise stated. Melt Flow Index (MFI) may be interchangeably referred to as Melt Flow Rate (MFR).

[0124] ●Seal strength ASTM F88-using heated sealing rods on both sides, 0.5 seconds, 400N / cm 2 Pressure, sealed to itself, peeled in machine direction, peeled on stretching unit at 300 mm / min, 15 mm width.

[0125] • The seal initiation temperature refers to the sealing temperature at which a seal strength of about 5 N / 15 mm is achieved.

[0126] • Tear strength, Trouser tear test, machine direction, ASTM D 1938. This test can provide further indication of the straight tear properties of the film.

[0127] Comparative Examples

[0128] Two sample films were produced to demonstrate that the orientation of the seal layer may have an adverse effect on the seal initiation temperature. A three-layer film was prepared by cast coextrusion, the seal layer having a blend of 67% polypropylene terpolymer (Tm = 131°C, MFR = 6.0 g / 10 min), 25% thermoplastic polyolefin copolymer (Tm = 142°C, MFR = 0.6 g / 10 min), 5% homopolymer polypropylene and 3% anti-blocking masterbatch. The film was laminated to two BOPP films to produce a first three-layer laminate structure. When the film was heat sealed, it was found that the seal initiation temperature of the laminate was about 121°C and the seal strength was 16.9 N / 15 mm when sealed at 130°C. These sealing properties are very desirable for boil-in packaging. The tear strength (trouser tear) of the film was about 1.6 N, which is acceptable. However, this laminate structure has very poor straight tear properties.

[0129] The second laminate was produced by first machine direction orientation (3: 1 stretch) of the three-layer cast coextruded film described above, and then laminating the MDO film to two BOPP films to form a second three-layer laminate structure. When the film was heat sealed, the seal initiation temperature of the laminate was found to be about 134°C and the seal strength at 130°C was less than 1N / 15mm. This shows that although the orientation of the sealing film can contribute to the tearing property performance, the damage to the heat sealing initiation temperature is unacceptable. The stretch ratio of the film is 3: 1. The tearing properties of the film can be improved by increasing the stretch ratio (i.e., 5: 1). However, due to the orientation of the sealing layer, this change will have a further adverse effect on the sealing performance.

[0130] Examples of the present invention

[0131] The film laminate was produced with the structure of [BOPP / adhesive / MDOPP / extrusion coated sealant]. The MDO film consisted of random PP stretched to a 5:1 ratio with a final thickness of 30 microns. 2The sealant was applied by weight. The sealant was 65% (by weight) polypropylene terpolymer (Tm = 131°C, MFR = 6.0 g / 10 min), 20% LDPE with long chain branches (MFR = 3.8 g / 10 min, Tm = 108°C at 190°C), 10% homopolymer polypropylene (MFR = 25 g / 10 min ISO 1133) and 5% random copolymer polypropylene (density = 0.88 g / cm 3 , MFR = 6 g / 10 min, at 230 ℃ / 2.16 kg). The measured MFR of the sealant blend was 7.7 g / 10 min. When the film was heat sealed, the seal initiation temperature was found to be about 125 ℃. The laminate exhibited a straight tear and a trouser tear value of 2.05N. The film has a total composition including 3.5% polyethylene, 94.2% polypropylene, 97.7% polyolefin and 2.3% non-olefin material (adhesive). It should be noted that if the MDOPP film is further optimized for sealing (such as the MDOPP film used in the comparative example above), even lower trouser tear values ​​can be achieved.

[0132] Film laminates were produced to demonstrate the effectiveness of incorporating MDOPP films into laminates and using extrusion coating to apply a sealant layer. The final laminate structure was BOPP / adhesive / MDOPP / sealant. The MDOPP film was a three-layer coextruded film that was stretched 5X in the machine direction to a final thickness of 30 microns. The MDOPP film had a core layer containing 100% homopolymer polypropylene, and surface layers of 80% heterophasic polypropylene block copolymer and 20% random copolymer polypropylene (density = 0.88 g / cm 3 , MFR = 6 g / 10 min at 230°C / 2.16 kg). The coating was extruded to obtain 24 g / m 2 The sealant was applied by weight. The sealant is a blend of about 50% polypropylene terpolymer (Tm=131°C, MFR=9 g / 10 min), about 25% random copolymer polypropylene, about 20.5% polypropylene and about 4.5% long chain branched LDPE. The melt flow rate of the sealant blend was calculated to be about 12.2 g / 10 min (at 230°C / 2.16 kg). When heat sealing the film, it was found that the seal initiation temperature of the laminate was about 123°C and the seal strength at 130°C was 13.7 N / 15 mm. The laminate also has favorable machine direction tear properties, clean straight tear and 1.2 N in the trouser tear test. The film has a total composition including 3.2% polyethylene, 94.5% polypropylene, 97.7% polyolefin and 2.3% non-olefin material (adhesive). This shows that the optimized MDOPP and extrusion coated sealant provide the desired combination of cook-appropriate seals and good machine direction tearing.

[0133] Unless expressly excluded or otherwise limited, each document cited in this application, including any cross-referenced documents, is incorporated by reference into this application in its entirety. The citation of any document does not admit that it is prior art with respect to any embodiment disclosed in this application, or that it teaches, indicates or discloses any such embodiment alone or in combination with any other reference document or multiple reference documents. Further, in the event that any meaning or definition of a term in this application conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to the term in this application shall prevail.

[0134] Unless otherwise indicated, all numbers expressing dimensions, amounts, ranges, limits, and physical and other properties used in this application are to be understood as being preceded in all instances by the term "about." Therefore, unless expressly indicated to the contrary, the numerical parameters set forth in this application are approximations that can vary depending on the desired properties sought to be obtained by one of ordinary skill in the art utilizing the teachings disclosed herein without undue experimentation.

[0135] As used in this application, the singular forms "a", "an", and "the" encompass embodiments having plural referents, unless the context clearly dictates otherwise. As used in this application, the term "or" is generally used in its sense, including "and / or", "unless" the context clearly dictates otherwise.

[0136] If used in this application, spatially relative terms, including but not limited to "lower," "upper," "beneath," "below," "above," "bottom," and "top," are used for ease of description to describe the spatial relationship of an element to another element. Such spatially relative terms encompass different orientations of the device in use or operation in addition to the specific orientations depicted in the figures and described in this application. For example, if an object depicted in a drawing is inverted or turned over, elements previously described as being below or beneath other elements would be above those other elements.

[0137] The accompanying drawings show some but not all embodiments. The elements depicted in the drawings are illustrative and are not necessarily drawn to scale, and the same (or similar) reference numerals represent the same (or similar) features throughout the drawings.

[0138] The disclosed descriptions, examples, embodiments, and figures are illustrative only and should not be construed as limiting. The present invention includes the disclosed descriptions, examples, embodiments, and figures; but is not limited to such descriptions, examples, embodiments, or figures. As briefly described above, the reader should assume that the features of one disclosed embodiment may also apply to all other disclosed embodiments unless expressly indicated to the contrary. Modifications and other embodiments will be apparent to those of ordinary skill in the packaging arts, and all such modifications and other embodiments are intended and considered to be within the scope of the present invention.

[0139] Retort packaging film embodiment

[0140] A. A retortable packaging film comprising:

[0141] A laminate comprising:

[0142] BOPP film, and

[0143] MDOPP membrane, and

[0144] a sealant layer disposed on the laminate and comprising a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE, the sealant layer having a melt flow index in the range of 5 g / 10 min to 25 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg, and

[0145] The total composition comprises at least 80 wt% polypropylene.

[0146] B. The retort packaging film according to any other retort packaging film embodiment, wherein the blend of the seal layer comprises 4 wt% to 50 wt% of the long chain branched polyethylene and 50 wt% to 90 wt% of the polypropylene terpolymer.

[0147] C. The retort packaging film according to any other retort packaging film embodiment, wherein the melting temperature of the polypropylene terpolymer is above 130°C.

[0148] D. The retort packaging film according to any other retort packaging film embodiment, wherein the seal initiation temperature of the seal layer is less than 140°C as measured using ASTM F88 Technique A.

[0149] E. The retort packaging film according to any other retort packaging film embodiment, wherein the melt flow index of the sealing layer is in the range of 5 g / 10 min to 15 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg.

[0150] F. The retort packaging film according to any other retort packaging film embodiment, wherein the seal layer is non-oriented.

[0151] G. The retort packaging film according to any other retort packaging film embodiment, wherein the seal layer is extrusion coated onto the laminate.

[0152] H. The retort packaging film according to any other retort packaging film embodiment, wherein the laminate further comprises a barrier layer attached to the BOPP film or the MDOPP film.

[0153] I. The retortable packaging film according to embodiment H, wherein the barrier layer comprises a metal layer or an oxide coating, and the metal layer or the oxide coating is deposited on the surface of the BOPP film or the MDOPP film.

[0154] J. The retortable packaging film according to embodiment H, wherein the barrier layer comprises a polymeric barrier material.

[0155] K. The retort packaging film according to any other retort packaging film embodiment, wherein the total composition comprises at least 90 wt% polypropylene.

[0156] L. The retort packaging film according to any other retort packaging film embodiment, wherein the total composition comprises less than 20 wt% of non-polyolefin materials.

[0157] M. The retort packaging film according to any other retort packaging film embodiment, wherein the total composition comprises less than 10 wt% of non-polyolefin materials.

[0158] N. The retort packaging film of any one of embodiments A to M, wherein the MDOPP film is located on an outer surface of the retort packaging film.

[0159] O. The retort packaging film according to any one of embodiments A to M, wherein the BOPP film is located on the outer surface of the retort packaging film.

[0160] Hermetically Sealed Packaged Food Product Embodiments

[0161] P. A hermetically sealed packaged food product comprising the retortable packaging film according to any one of embodiments A to O.

[0162] Method Embodiment

[0163] Q. A method for producing a retortable packaging film, the method comprising:

[0164] laminating a BOPP film to an MDOPP film to form a pre-laminate, and

[0165] extrusion coating a sealant layer onto the prelaminate,

[0166] The sealing layer comprises a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE, and the melt flow index of the sealing layer is in the range of 5 g / 10 min to 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg.

[0167] R. A method for producing a retortable packaging film, the method comprising:

[0168] extruding a film and orienting the film in a machine direction to produce an MDOPP film;

[0169] Extrusion coating a sealing layer onto the MDOPP film;

[0170] applying a barrier coating to the BOPP film; and

[0171] Adhesive lamination of the MDOPP film and the BOPP film;

[0172] The sealing layer comprises a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE, and the melt flow index of the sealing layer is in the range of 5 g / 10 min to 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg.

Claims

1. A retortable packaging film, comprising: A laminate comprising: BOPP film, and MDOPP membrane, and a sealant layer disposed on the laminate and comprising a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE, the sealant layer having a melt flow index in the range of 5 g / 10 min to 25 g / 10 min according to ASTM D1238 Procedure A Condition 230°C / 2.16 kg, and The total composition comprises at least 80 wt% polypropylene.

2. The retortable packaging film according to claim 1, wherein the blend of the sealant layer comprises 4 to 50 wt% of the long chain branched polyethylene and 50 to 90 wt% of the polypropylene terpolymer.

3. The retortable packaging film according to claim 1, wherein the melting temperature of the polypropylene terpolymer is higher than 130°C.

4. The retortable packaging film of claim 1, wherein the seal initiation temperature of the seal layer is less than 140°C as measured using ASTM F88 Technique A. 5 . The retortable packaging film according to claim 1 , wherein the melt flow index of the sealing layer is in the range of 5 g / 10 min to 15 g / 10 min according to ASTM D1238 Procedure A Condition 230° C. / 2.16 kg. The retortable packaging film according to claim 1 , wherein the sealing layer is non-oriented.

7. The retortable packaging film of claim 1, wherein the sealant layer is extrusion coated onto the laminate. 8 . The retortable packaging film of claim 1 , wherein the laminate further comprises a barrier layer attached to the BOPP film or the MDOPP film. 9 . The retortable packaging film according to claim 8 , wherein the barrier layer comprises a metal layer or an oxide coating layer deposited on a surface of the BOPP film or the MDOPP film.

10. The retortable packaging film of claim 8, wherein the barrier layer comprises a polymeric barrier material.

11. The retortable packaging film of claim 1, wherein the total composition comprises at least 90 wt% polypropylene.

12. The retortable packaging film of claim 1, wherein the total composition comprises less than 20 wt% of non-polyolefin materials.

13. The retortable packaging film of claim 1, wherein the total composition comprises less than 10 wt% of non-polyolefin materials.

14. The retort packaging film of claim 1, wherein the MDOPP film is located on an outer surface of the retort packaging film.

15. The retort packaging film according to claim 1, wherein the BOPP film is located on an outer surface of the retort packaging film.

16. A hermetically sealed packaged food product comprising the retortable packaging film according to claim 1.

17. A method for producing a retortable packaging film, the method comprising: laminating a BOPP film to an MDOPP film to form a pre-laminate, and extrusion coating a sealant layer onto the prelaminate, The sealing layer comprises a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE, and the melt flow index of the sealing layer is in the range of 5 g / 10 min to 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg.

18. A method for producing a retortable packaging film, the method comprising: extruding a film and orienting the film in a machine direction to produce an MDOPP film; Extrusion coating a sealing layer onto the MDOPP film; Applying a barrier coating to a BOPP film; as well as Adhesive lamination of the MDOPP film and the BOPP film; The sealing layer comprises a blend including a polypropylene terpolymer and a long chain branched polyethylene selected from the group consisting of LDPE and MDPE, and the melt flow index of the sealing layer is in the range of 5 g / 10 min to 25 g / 10 min according to ASTM D1238 procedure A condition 230°C / 2.16 kg.

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