Patent Application
20250153925
This disclosure is related to flexible microwavable packages that are dimensionally stable and heat, puncture, or stain resistant. The flexible microwavable packages may be recyclable.
Flexible microwavable packages generally include stand-up pouches, quad-seal bags, pillow packs or pouches, or sachets. The packages contain products that are microwavable, such as food products that are fresh or frozen foods, or non-food products, such as pharmaceuticals. The packages are often made from laminated films that include an oriented polyester film (OPET) or an oriented polypropylene film (OPP) laminated to a sealant film that is polyethylene (PE)- or polypropylene (PP)-based. The oriented films provide stiffness, printing quality and heat resistance to the laminated films. Many countries do not have the necessary recycling systems to recycle these mixed polymer laminates.
The push towards recyclability has led to the development of monopolymer-based films and packages. Monopolymer-based films are recyclable as all layers are made of the same type of polymer, which makes sorting easier and leads to cleaner recycling streams. The monopolymer-based film is often made from polyethylene or polyethylene-based polymers.
Flexible, polyethylene or polyethylene-based microwavable packages (i.e., monopolymer-based films) are susceptible to being exposed to high temperatures when the package contents are heated by microwaves.
Flexible microwavable packages can be used to contain a wide variety of products including food and non-food products. Uneven heating may occur when microwave cooking food products that may be attributed to product(s) size, product composition, product density, or product fat content, among other things, that can cause the flexible packaging material to become extremely warm or hot in localized areas. The hot product temperatures may cause the flexible packaging material to warp or distort. Package failure (e.g., film weakness, formation of holes, film tearing, etc.) may further occur that may allow product to leak from the package.
Polyethylene or polyethylene-based packaging films may be recycled. However, polyethylene or polyethylene-based packaging films may not resist the warping, distortion or failure that can result from cooking products with microwaves in a package made from these films. For example, package contents that include food products having a fat content, when cooked in the microwave according to the manufacturer's instructions, frequently reach temperatures that are higher than the glass transition temperature or the melting point of the polyethylene or polyethylene-based film that forms the package.
Flexible packaging materials that include heat-resistant polymers, such as polyamide or polypropylene, may resist warping, distortion, and failure. However, the above-mentioned polymers, among others, may not be recyclable in a monopolymer recycling stream, such as a polyethylene-based recycling stream.
This disclosure relates to flexible microwave packages that can resist warping, distortion and failure and further may be recycled in a polyethylene-based recycling stream.
In an embodiment, a microwavable package may include a sidewall including a film including a first surface and a second surface. The package may include a patch including a film including a first surface and a second surface. The package includes a seal that connects the sidewall to itself. The package includes a top portion and a bottom portion. The sidewall film is a monopolymer-based film. The first surface of the sidewall is an exposed surface of the sidewall. The second surface of the sidewall is a sealant surface of the sidewall. The patch is a heat-resistant polymer-based film. The patch is positioned in the bottom portion of the package. The patch may include a thermal conductivity value from 0.11 Watts/meter·degree Kelvin (W/m·K) to 0.44 W/m·K at 25° C. (77° F.) when measured according to ASTM 1530-11.
In another embodiment, a microwavable package may include a first sidewall including a first sidewall film including a first exposed surface and a first sealant surface. The package may include a second sidewall including a second sidewall film including a second exposed surface and a second sealant surface. The package may include a patch including a film including a first surface and a second surface. The package may include a seal that connects the first sidewall to the second sidewall. The package includes a top portion and a bottom portion. The first sidewall film is a first monopolymer-based film. The second sidewall film is a second monopolymer-based film. The patch is a heat-resistant polymer-based film. The patch is positioned in the bottom portion of the package. The patch is attached to the first sidewall, the second sidewall or a combination thereof. The patch includes a thermal conductivity value from 0.11 Watts/meter·degree Kelvin (W/m·K) to 0.44 W/m·K at 25° C. (77° F.) when measured according to ASTM 1530-11.
Other features that may be used individually or in combination with respect to the embodiments are as follows.
The patch first surface may be connected to the second surface of the sidewall.
The patch second surface may be connected to the second surface of the sidewall.
The package may include a food product. Further, the food product may be a frozen food product.
The food product may include a fat content from 0.3% to 7%.
The monopolymer-based film may be a polyethylene-based film.
The heat-resistant polymer-based film may include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polypropylene (PP), polyester (PET), polyamide (PA), or combinations thereof.
The heat-resistant polymer-based film may include high density polyethylene, polypropylene, polyamide, or combinations thereof.
The patch may be positioned independently of the seal.
The package may include a vent.
The patch may be positioned independently of the vent.
The package may be suitable for recycling.
The total composition of the package may include between 90% and 99% polyethylene-based polymer, by weight.
The package may include an additional patch positioned in the bottom of the package.
In another embodiment, a packaged product may include a sidewall that includes a film including a first surface and a second surface. The packaged product may include a patch including a film including a first surface and a second surface, a seal, and a product. The seal connects the sidewall forming a package. The package includes a package body. The sidewall film is a monopolymer-based film. The first surface of the sidewall is an exposed surface of the sidewall. The second surface of the sidewall is a sealant surface of the sidewall. The patch is a heat-resistant polymer-based film. The product is contained in the package body. The product may include a fat content from 0.3% to 7%. The product is positioned in a portion of the package that comprises the patch when the package is in an upright position. The patch may include a thermal conductivity value from 0.11 Watts/meter·degree Kelvin (W/m·K) to 0.44 W/m·K at 25° C. (77° F.) when measured according to ASTM 1530-11.
Other features that may be used individually or in combination with respect to the embodiment are as follows.
The patch first surface may be connected to the second surface of the sidewall.
The patch second surface may be connected to the second surface of the sidewall.
The package may include a food product. Further, the food product may be a frozen food product.
The food product may include a fat content from 0.3% to 7%.
The monopolymer-based film may be a polyethylene-based film.
The heat-resistant polymer-based film may include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polypropylene (PP), polyester (PET), polyamide (PA), or combinations thereof.
The heat-resistant polymer-based film may include high density polyethylene, polypropylene, polyamide, or combinations thereof.
The patch may be positioned independently of the seal.
The package may include a vent.
The patch may be positioned independently of the vent.
The package may be suitable for recycling.
The total composition of the package may include between 90% and 99% polyethylene-based polymer, by weight.
The package may include an additional patch positioned in the bottom of the package.
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:
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.
Described herein are flexible microwavable packages that are dimensionally stable and that may be heat, puncture, or stain resistant. The flexible microwavable packages may also be recyclable. The microwavable package includes a sidewall that is formed from a monopolymer-based flexible film. The microwavable packages include a patch that provides dimensional stability to the package.
Suitable products that may be contained in the flexible microwavable packages may include, but are not limited to, fresh food, refrigerated foods, frozen foods, shelf-stable foods, pharmaceuticals, nutraceuticals, medical products, consumer goods, cosmetics, and chemicals. Many products, such as food products, may include a fat content from 0% to 100% by weight of the product per a single portion (e.g., serving) of the food product. The term “fat content”, as used herein, refers to the weight of total fat contained in each portion of product and is expressed as a percentage of the product weight. Total fat refers to the sum of saturated fat, trans fat, monounsaturated fat, and polyunsaturated fat in a single portion of the product. For example, nutritional labels found on packaged food products in the United States include a total fat content represented in grams per serving. Total fat information in grams per serving may be used to determine the fat content, as used herein, as a percentage of a single portion of the product by weight. A fat content of 0% indicates that the product is completely devoid of fat and a fat content of 100% indicates that the product is completely composed of fat. In an embodiment, the fat content of a product may be from 0% to 100% or any percentage therebetween, by weight, of a given portion of the product. In other embodiments where the product is a food product, the fat content may be from 0.1% to 30%, 0.2% to 20%, 0.3% to 10%, or any percentage therebetween, by weight, of a given portion of the food product. In other embodiments, the fat content may be from 0.3% to 7% or any percentage therebetween, by weight, of a given portion of the product.
Food products may include fresh foods such as dairy (e.g., milk, cheese, etc.), vegetables, and proteins, such as beef, pork, poultry, fish, or seafood, or frozen foods such as dairy, vegetables and proteins. In some instances, frozen food products may be a combination of food products. Non-limiting examples of frozen food products include frozen dairy and vegetables (e.g., frozen broccoli and cheese sauce) and frozen protein and vegetables (e.g., frozen entrée of beef, mixed vegetables, and gravy/sauce).
A “monopolymer-based film”, as used in this application, refers to a film that is comprised predominantly of a single polymer classification (i.e., monopolymer). Examples of a monopolymer would be polyethylene, polypropylene, polyamide, etc. Monopolymer does not necessarily refer to the number of layers included in the monopolymer-based film. The monopolymer-based film can be produced with mono- or co-extrusion or via lamination of multiple films that include the same single polymer classification. The term “monopolymer-based” as used herein, refers to an article (i.e., a package, a film, a layer, etc.) that includes high levels of a monopolymer. In some cases, a monopolymer-based article includes at least 50% monopolymer. In some other cases, a monopolymer-based article includes at least 50% polyethylene-based polymers.
In some embodiments, the monopolymer-based film may include a single polymer, which may be suitable for single polymer recycling streams. In such embodiments, the overall amount of the single polymer shall be at a high level and any additives used should be kept to a minimum. Any non-single polymers present should be minimized. In these embodiments, the total composition of the monopolymer-based films may include between 90% and 100% of a single polymer by weight, including any range or combination of ranges therein. In some embodiments, the total composition of the monopolymer-based films is greater than 90%, or greater than 95% of a single polymer by weight. In an embodiment, the single polymer is present in an amount from 95% to 100% of the monopolymer-based film by weight.
As used herein, the term “polyethylene-based” refers to an article (i.e., a package, a film, a layer, etc.) that includes high levels of polyethylene-based polymers. In some cases, a polyethylene-based article has at least 50% polyethylene-based polymers, by weight. A polyethylene-based article may have at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or any range or combination of ranges therein of polyethylene-based polymers, by weight. In some cases, a polyethylene-based article consists of polyethylene-based polymers. The article may be accompanied by other minor components such as slip, antiblock, processing aid, nucleation additives, or hydrocarbon additives, for example.
As used herein, the term “polyethylene-based polymer” refers to a polymer that possesses ethylene linkages and maintains a glass transition temperature below 50° C. The polymer may be a homopolymer of ethylene or a copolymer of ethylene and other monomers. Examples of polyethylene-based polymers include but are not limited to low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLPDE), metallocene-catalyzed linear-low density polyethylene (mLLDPE), ethylene-vinyl acetate copolymer (EVA), cyclic olefin copolymers (COC), and maleic anhydride grafted polyethylene (MAH-PE). As used herein, “polyethylene-based polymer” does not encompass ethylene vinyl alcohol copolymers (i.e., EVOH, saponified or hydrolyzed ethylene vinyl acetate copolymer or vinyl alcohol copolymer having an ethylene comonomer). For example, EVOH may be used to increase gas barrier properties if desired for the particular package application. EVOH is not considered to be a polyethylene-based polymer as described herein, as it can cause issues in a polyethylene-based recycling stream. In an embodiment, the total composition of the monopolymer-based film may include between 0% and 5% ethylene vinyl alcohol copolymer, by weight. In another embodiment, the total composition of the monopolymer-based film may include between 0% and 10% ethylene vinyl alcohol copolymer, by weight.
In some cases, the monopolymer-based article includes polyethylene-rich articles. The term “polyethylene-rich”, as used herein, refers to an article (i.e., a package, a film, a layer, etc.) that includes very high levels of polyethylene-based polymers. In some cases, a polyethylene-rich article has at least 90% polyethylene-based polymers, by weight. For example, the polyethylene-rich article may have at least 92%, at least 94%, at least 96%, at least 98%, 100%, or any range or combination of ranges therein of polyethylene-based polymers, by weight. In some cases, a polyethylene-rich article consists of polyethylene-based polymers.
The monopolymer-based film may be a monolayer or a multilayer film. As used herein, the term “film” is a monolayer or multilayer web that has an insignificant z-direction dimension (thickness) as compared to the x- and y-direction dimensions (length and width). Films are generally regarded as having two major surfaces, opposite each other, expanding in the length and width directions. The surface of the film that is not connected to another layer or film is an exposed surface of the film. Films may be built from an unlimited number of films or layers, the films or layers being bonded together to form a multilayer film. With reference to
With reference to
Referring to
The second film may be a sealant film. A “sealant film” has at least one exposed sealant surface that is sealable (e.g., seals, connects, adheres, attaches, etc.) to itself or another film to form a seal. That is, the exposed sealant surface softens when exposed to heat and returns to its original condition when cooled to room temperature. In some cases, the seal is hermetic. For example, second surface 19 of the second film 14 may include a sealant surface
The term “layer”, as used herein, refers to a building block of films that is a structure of a single polymer or a homogeneous blend of materials. A layer may contain other non-polymeric materials and may have additives. Layers may be continuous or discontinuous (i.e., patterned) with the length and width of the film. In a monolayer film, “film”, “sheet” and “layer” are synonymous.
In some embodiments, the first film may be an oriented film, for example a film of oriented polyethylene. The term “oriented”, as used herein, refers to a film, sheet, web, etc. that has been elongated in at least one of the machine direction or the transverse direction. Such elongation is accomplished by procedures known in the art. Non-limiting examples of such procedures include a single bubble blown film extrusion process and a slot cast sheet extrusion process with subsequent stretching, for example, by tentering, to provide orientation. Machine direction orientation may be accomplished by the use of nip rolls rotating at different speeds, pulling or drawing the film tube in the machine direction. In some embodiments, the first film is oriented for aesthetics, rigidity, or abuse resistance of a package resulting from the monopolymer-based film.
The first film 12 and the second film 14 are each shown as monolayer films in
In some embodiments, the first film, the second film or both of the first film and the second film are a blown film. The term “blown film”, as used herein refers to a film produced by the blown coextrusion process. In the blown coextrusion process, streams of melt-plastified polymers are forced through an annular die having a central mandrel to form a tubular extrudate. The tubular extrudate may be expanded to a desired wall thickness by a volume of fluid (e.g., air or other gas) entering the hollow interior of the extrudate via the mandrel, and then rapidly cooled or quenched by any of various methods known to those of skill in the art.
In some other embodiments, at least one additional layer may be positioned between the first film and the second film. With reference to
In other embodiments, the first additional layer may be positioned on the first surface of the first film of the monopolymer-based film. With reference to
In an embodiment, the monopolymer-based film may include multiple additional layers in addition to the first additional layer. That is, a second additional layer, a third additional layer and so on. The additional layers may be continuous or discontinuous. The additional layers may differ in composition. The additional layers may be positioned between the first film and the second film and/or exterior to the first surface of the first film. As many additional layers as desired may be utilized in the final film structure as long as the spirit of embodiments disclosed herein is met, namely, a package that includes a monopolymer-based film and a patch that provides dimensional stability and integrity.
The first film may have a thickness from 10 microns to 100 microns, preferably from 20 microns to 50 microns. The second film may have a thickness from 10 microns to 100 microns, preferably from 20 microns to 50 microns. The monopolymer-based film may have a thickness from 20 microns to 200 microns, preferably from 40 microns to 100 microns.
In other embodiments, the monopolymer-based film may be a multilayer, coextruded film. Referring to
The tie layer 46 may provide adhesion between the first layer 42 and the second layer 44 (i.e., adhesive or tie materials). The terms “tie material”, “polymeric adhesive layer”, “adhesive layer”, or “tie layer”, as used herein, refer to a polymeric material serving a primary purpose or function of adhering two surfaces to one another, typically the planar surfaces of two film layers. A tie material adheres one film layer surface to another film layer surface. The tie material may comprise any polymer, copolymer or blend of polymers having a polar group or any other polymer, homopolymer, copolymer or blend of polymers, including modified and unmodified polymers (such as grafted copolymers), which provide sufficient interlayer adhesion to adjacent layers comprising otherwise non-adhering polymers. In some embodiments, a lamination layer is not included. The second layer may be a sealing layer. In other embodiments, the monopolymer-based films may be coextruded to include supplemental layers that are polyethylene-based. In other embodiments, the monopolymer-based films may include additional layers such as printing, ink, coatings, etc. The coextruded, multilayer, monopolymer-based film may have a thickness from 10 microns to 100 microns, preferably from 20 microns to 50 microns.
A heat-resistant polymer-based film may be a monolayer or multilayer film. The heat-resistant polymer-based film may include a laminated film, a coextruded film, or combinations thereof. In some embodiments, the heat-resistant polymer-based film may be monopolymer-based. In other embodiments, the heat-resistant polymer-based film is a polyethylene-based film and in some other embodiments, a polyethylene-rich film. In some embodiments, the heat-resistant polymer-based film includes HDPE, LDPE, LLDPE, polypropylene (PP), polyesters (poly-ethylene terephthalate, PET), polyamides (e.g., PA6, PA6,6, PA12, etc.), or combinations thereof. In an embodiment, the heat-resistant polymer-based film includes HDPE, polyamides, PP, or combinations thereof.
As used throughout this application, the terms “polypropylene” or “PP” refer to a plastomer, homopolymer or copolymer having at least one propylene monomer linkage within the repeating backbone of the polymer. The propylene linkage may be represented by the general formula: [CH2CH(CH3)]n. Such polypropylene may be a polypropylene impact copolymer, a polypropylene random copolymer, or a polypropylene homopolymer, may be syndiotactic or isotactic, or may or may not be clarified.
As used herein, the term “polyester” refers to homopolymers and copolymers having recurring ester linkages which may be formed by any method known in the art. Recurring ester linkages may be formed by the reaction of one or more diols with one or more diacids. Non-limiting examples of suitable diols include ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, resorcinol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and polyoxytetramethylene glycol. Non-limiting examples of suitable diacids include terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 2,5-furandicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, trimellitic anhydride, succinic acid, adipic acid, and azelaic acid.
Non-limiting examples of suitable polyesters include poly(ethylene terephthalate) (PET), poly(ethylene terephthalate-co-cyclohexanedimethanol terephthalate) (PETG), poly(butylene terephthalate) (PBT), poly(ethylene naphthalate) (PEN), poly(ethylene furanoate) (PEF), poly(propylene furanoate) (PPF), and poly(butylene adipate-co-terephthalate) (PBAT).
Suitable polyesters may also be formed by the ring-opening polymerization of suitable cyclic monomers like lactides to form, for example, poly(lactic acid) (PLA), glycolides to form, for example, poly(glycolic acid) (PGA), and lactones to form, for example, poly(caprolactone) and poly(butyrolactone).
Suitable polyesters may also be formed by the direct condensation reaction of alpha hydroxy acids. For example, PGA may be formed by the condensation reaction of glycolic acid.
Suitable polyesters may also be synthesized by microorganisms. Examples of suitable polyesters include various poly(hydroxy alkanoates) like poly(hydroxy butyrate) (PHB) and poly(hydroxy valerate) (PHV).
As used throughout this application, the terms “polyamide” or “PA” or “nylon” refer to a homopolymer or copolymer having an amide linkage between monomer units and formed by any method known in the art. Recurring amide linkages may be formed by the reaction of one or more diamines and one or more diacids. Non-limiting examples of suitable diamines include 1,4-diamino butane, hexamethylene diamine, decamethylene diamine, metaxylylene diamine and isophorone diamine. Non-limiting examples of suitable diacids include terephthalic acid, isophthalic acid, 2,5-furandicarboxylic acid, succinic acid, adipic acid, azelaic acid, capric acid and lauric acid.
Polyamides may also be formed by the ring-opening polymerization of suitable cyclic lactams like ε-caprolactam, ω-undecanolactam and ω-dodecalactam.
Non-limiting examples of suitable polyamides include poly(ε-caprolactam) (nylon 6), poly(ω-undecanolactam) (nylon 11), poly(ω-dodecalactam) (nylon 12), poly(hexamethylene adipamide) (nylon 6,6), poly(hexamethylene adipamide-co-caprolactam) (nylon 66/6), poly(caprolactam-co-hexamethylene adipamide) (nylon 6/66), poly(caprolactam-co-hexamethylene azelamide) (nylon 6/69), poly(m-xylylene adipamide) (MXD6) and poly(hexamethylene terephthalamide-co-hexamethylene isophthalamide) (nylon 6I/6T).
The heat-resistant polymer-based film is resistant to the effects of heat. The heat-resistant polymer-based film is dimensionally stable; that is, the film does not shrink or otherwise distort (e.g., wrinkle, blister, form holes, stretch, etc.) when exposed to temperatures found in microwave cooking conditions. Microwave cooking conditions may include, for example, temperatures in excess of 93° C. (200° F.), 107° C. (225° F.), 121° C. (250° F.), 135° C. (275° F.), 149° C. (300° F.), 177° C. (350° F.), 204° C. (400° F.), or any temperature therebetween.
Dimensional stability can be characterized and quantified by analyzing the stretch of a film at elevated temperatures. During the development of the flexible microwavable packages disclosed herein, the inventors found that the dimensional stability of films can be characterized by a property defined as “thermal strain value”. The thermal strain value is a useful measurement for predicting the heat resistance of heat-resistant polymer-based films that may be used for the dimensionally stable flexible microwavable packages.
The thermal strain value of the heat-resistant polymer-based films may be below 0.5% at temperatures below 120° C. The difference of the thermal strain value between the heat-resistant polymer-based film and the monopolymer-based film at 80° C. may be between 0% and 1.0%, at 100° C. may be between 0% and 2.0%, and at 120° C. may be between 0% and 4.0%.
The heat-resistant polymer-based film further includes a thermal conductivity value that is a material property that describes ability to conduct heat. As used throughout this application, the term “thermal conductivity” refers to the quantity of heat transmitted through a unit thickness of the heat-resistant polymer-based film in a direction normal to a surface of unit area due to a unit temperature gradient under steady state conditions. In other words, the thermal conductivity is a measure of heat flow through a material and is representative of the resistance of materials to thermal transmission. Thermal conductivity values are directly proportional to the insulative behavior of the material. That is, relatively high thermal conductivity values are representative of conducting heat very well and having little to no insulative behavior, where relatively low thermal conductivity values are representative of not conducting heat well and having insulative behavior. The term “non-insulative”, as used in this application, refers to thermal conductivity values representative of conducting heat well with low to no insulative behavior.
The heat-resistant polymer-based films of the present disclosure include a thermal conductivity value from 0.11 Watts/meter·degree Kelvin (W/m·K) to 0.44 W/m·K at 25° C. (77° F.) when measured according to ASTM 1530-11. The thermal conductivity values may be from 0.11 W/m·K to 0.44 W/m·K, 0.22 W/m·K 0.33 W/m·K, 0.44 W/m·K, or any range or combination of ranges therein. Heat-resistant polymer-based films including thermal conductivity values in this range transfer heat such that they are non-insulative. In an embodiment, heat-resistant polymer-based films including polyamide may include a thermal conductivity value of 0.25 W/m·K. In another embodiment, heat-resistant polymer-based films including high density polyethylene may include a thermal conductivity value from 0.42 W/m·K to 0.44 W/m·K. In a further embodiment, heat-resistant polymer-based films including low density polyethylene may include a thermal conductivity value of 0.33 W/m·K. In another embodiment, heat-resistant polymer-based films including polypropylene may include a thermal conductivity value from 0.11 W/m·K to 0.22 W/m·K.
For comparison, thermal insulating materials may include a thermal conductivity value from 0.08 W/m·K or less. A common thermal insulating material that has a plurality of air-filled cavities disposed between thermoplastic sheets or films (i.e., bubble wrap) includes thermal conductivity values from 0.027 W/m·K or less. The thermal conductivity values of thermal insulating material, in some cases, is notably at least one order of magnitude different from the thermal conductivity values of the heat-resistant polymer-based films of the present disclosure. The heat-resistant polymer-based film of the present disclosure is not insulative. Further, the heat-resistant polymer-based film of the present disclosure does not include air-filled cavities disposed between films or within a film (i.e., foamed film).
Additionally, the heat-resistant polymer-based film is transparent to microwave energy. That is, the heat-resistant polymer-based film does not react (i.e., absorb or reflect) to microwave energy, such as a susceptor that is known in the art of microwavable packages.
Flexible microwave packages may warp, distort or fail when exposed to temperatures above the glass transition temperature or the melting point of the monopolymer-based film (e.g., polyethylene or polyethylene-based film) that forms the package sidewall. The warping, distortion, or failure of the packaging film (e.g., stretching, blistering, wrinkling, holes, weakness, etc.) may affect package integrity such that package stability is negatively affected. The package may not stand or lie as intended or may present difficulty for an end user to grab or hold the package (e.g., package tips over or collapses onto itself, formation of holes in the package, etc.). Further, the warping or distortion of the packaging film may affect package appearance that includes graphics, printing, or usage instructions such that they are misshapen, unreadable, or aesthetically not pleasing. Additionally, holes may allow product leakage that can pose potential burn hazards to a consumer or cause consumer frustration from creating a mess in the microwave. Flexible microwave packages may include a heat-resistant polymer-based film patch that may aid the package in resisting warping, distortion, or failure.
Packages of the present disclosure are not limited to the formats of stand-up pouches, quad-seal bags, pillow packs or pouches, or sachets. The packages include a sidewall of the monopolymer-based film and a patch of the heat-resistant polymer-based film. The sidewall includes the properties of the monopolymer-based film and the patch includes the properties of the heat-resistant polymer-based film as previously described. The sidewall is sealed by a seal to form a package body that can contain a product that may be any type of consumer or industrial item, medical product, pharmaceutical item, food item, or non-food item.
The package includes a top portion, a bottom portion, a height, and a width. The bottom portion of the package opposes the top portion of the package and corresponds to a portion of the package that rests on a shelf or surface when the package is in an upright manner (e.g., upright position). For example, the bottom portion includes the portion of the package at the bottom as the package typically sits on a table or surface in normal use of the package (e.g., product rests at bottom of package due to gravity, package graphics or instructions (if included) are shown as intended in a readable manner). The package includes a horizontal centerline that is parallel to the surface upon which the package may rest when placed in an upright manner. The horizonal centerline is positioned at half of the height of the package. The horizontal centerline bisects the package into the top portion and the bottom portion such that the top portion includes 50% of the package above the horizontal centerline and the bottom portion includes 50% of the package below the horizontal centerline.
The packages may include a ventilation feature that allows for air movement from within the package body to the environment exterior to the package. The ventilation feature can be useful when cooking a product that is contained in the package, for example, to allow steam to vent from the package. The ventilation feature may include, for example, perforations, micro-perforations, slits, or small holes in the panels, or tortuous paths formed in the seals.
The packages may be produced with additional features or components such as tear lines, tear notches and mechanical closures (e.g., hook and loop, press and close, zipper). These features may facilitate easy opening and reclosing of the package after the initial opening.
The patch is positioned in the bottom portion of the package. The patch may include from 20% to 100% of the bottom portion or any range or combination of ranges therein. The patch includes a first surface and a second surface that correspond to the previously described heat-resistant polymer-based film first surface and second surface. The patch first surface or the patch second surface may be attached (e.g., connected) to the sidewall that includes the monopolymer-based film. In some embodiments, the patch may be positioned on the sidewall that includes the first surface (exposed surface) of the monopolymer-based film. In other embodiments, the patch may be positioned on the sidewall that includes the second surface (sealant surface) of the monopolymer-based film. In some embodiments, the first surface of the patch that includes the heat-resistant polymer-based film may be attached to the sidewall that includes the second surface of the monopolymer-based film. In some other embodiments, the second surface of the patch that includes the heat-resistant polymer-based film may be attached to the sidewall that includes the second surface of the monopolymer-based film. The patch may be positioned independently of the seal that forms (e.g., closes) the package. The patch is positioned independently of any ventilation feature. The patch may be attached to the monopolymer-based film by means of adhesive, for example, a cut and placed film lamination or a die cut label, or any other means known by one of skill in the art.
Packages may include additional patches. For example, a first additional patch, a second additional patch, and so on. For packages that include multiple patches, the combination of the patches includes that the patches include heat-resistant polymer-based films, the patches are positioned in the bottom portion of the package and all the other requirements of a single patch as previously described.
In one non-limiting embodiment that is shown in
In another non-limiting embodiment that is shown in
The patch may provide heat resistance to the package. For example, polyethylene-based sidewall packages without a patch that contain products including a fat content may become very warm or hot when exposed to microwave energy that allows the fat to migrate into the sidewall film causing warping, distortion, or failure of the film. Polyethylene-based sidewall packages that include a patch and contain products including a fat content may also become very warm or hot when exposed to microwave energy. However the patch may prevent the fat from migrating into the sidewall film and thus provides heat resistance that prevents or minimizes warping, distortion, or failure of the sidewall film. The patch may also provide puncture or stain resistance to the package.
As previously described, the patch is not insulative. For example, the portion of the package that includes the patch may exceed a temperature of 60° C. (140° F.). Temperatures above 60° C. may cause irreversible human epidermal injury (i.e., human skin) at contact times of 5 seconds or greater according to ASTM C1055-20 (“Standard Guide for Heated System Surface Conditions that Produce Contact Burn Injuries”). In other words, a package including a patch, when exposed to microwave energy, may reach a temperature in a portion of the package that includes the patch, that exceeds a reversible injury level. Temperatures exceeding the reversible injury threshold may be reached when the package contains product with low fat levels, such as 7% or lower, and is exposed to microwave energy.
The packages disclosed herein may be suitable for recycling. As used herein, the terms “suitable for recycling” and “recyclable” refer to treatment of or processes applied to used materials to make the materials suitable for reuse. In some instances, recyclable is intended to reflect that the material can be easily processed in a recycling process that accepts “all-polyethylene” articles or “all-polyolefin” articles. In other instances, recyclable is intended to reflect that the material meets recycled content standards established by organizations (e.g., The Association of Plastic Recycling or Recycled Material Standard). Typically, these recycling processes can accept low levels of some contaminant material. As such, recyclable further reflects the packaging film having very high levels of polyethylene and low levels of acceptable contaminates. The total composition defined by weight of materials defines the recyclability of the packaging film. As described herein, the “total composition” of the package refers to all components and materials, including the sidewall, patch, zipper, and any other additional components. The total composition of the package may include between 90% and 99% polyethylene-based polymer, by weight. In some embodiments, the total composition of the package is greater than 90%, or greater than 95% polyethylene-based polymer, by weight. In some other embodiments, the packages may include a total composition including at least 95% polyethylene-based polymer, by weight.
In some embodiments where the heat-resistant polymer-based film that forms the patch does not include greater than 90% polyethylene-based polymer, by weight, the patch may be removed from the package (e.g., peeled off if applied as an adhesive label or cut away) and the patch and the sidewall material may be placed in the respective waste and recycling streams.
Microwave Cooking: Packages were prepared and filled with 284 g (10 ounces) of frozen broccoli with a frozen cheese sauce puck. The fat content of the frozen broccoli and cheese product was approximately 2% per a 106 g serving. The filled packages were exposed to microwave energy for 7 minutes in a 1,000 watt microwave oven. Immediately after cooking, the temperature of the exterior of the bottom of the package was taken with a non-contact infrared (IR) temperature meter. The packages were observed for distortion, warping and failure. Sample size equaled 5 packages.
Thermomechanical analysis-thermal strain value measurement: A Thermomechanical Analysis (TMA) procedure utilizing Dynamic Mechanical Analysis (DMA)/TMA test equipment was used for the procedure, such as TA Instruments Q800 DMA with DMA Controlled Force Module. The film deformation was measured under a controlled tension force (non-oscillating) over a temperature range. A 6.3 mm wide by at least 25.0 mm long film sample was cut and loaded into the film tension clamp. The clamp was tightened to a clamp force recommended by the manufacturer to hold the sample without slippage. An approximate distance of 12 mm was between the clamps. The film was cut and clamped such that the force was applied in the machine direction of the film. A preload (static) force of 0.504 N was applied to the sample and the initial distance was recorded. The equipment was then equilibrated to 35° C. The testing was executed using a constant force temperature ramp where the temperature was ramped at a speed of 10° C./minute from 35° C. to 130° C., while a constant force of 0.504 N was applied. During the test, the displacement of the clamps (i.e., the stretching or shrinking of the film) was measured. The thermal strain value (%) was then calculated and reported as a function of temperature, resulting in a thermal strain value curve. The thermal strain value (%) is the displacement distance divided by the initial distance. Normalized data can be collected by remeasuring the sample at equilibrium temperature. Sample size equaled 10 samples of each film.
Pillow Pouch: Packages in the format of pillow pouches were prepared with sidewalls formed from polyethylene-based film (oriented polyethylene, OPE) and a patch. The sidewall film structure was a lamination of 90 ga OPE/ink/adhesive/2.0 mil white linear low density PE (LLDPE). The sidewall film thickness was 73.7 microns (2.9 mil). The patch was a die cut label and included a polypropylene structure. The patch structure was 65 ga PP/adhesive/polyvinylidene chloride (PVDC)/2.0 mil PP with an acrylic-based adhesive coating applied at 13.8 lbs/rm onto the 65 ga PP surface. The patch was adhered on the sealant surface of the sidewall. The patch occupied 100% of the bottom portion of the package and was independent of the package seal. The patch included a thermal conductivity value of approximately 0.22 W/m·K. The patch thickness was 73.7 microns (2.9 mil). Package dimensions were 20.32 cm by 22.54 cm (8.000 inches by 8.875 inches). The packages included 67, 400 microns laser perforations in the top portion of the package.
Comparative Pillow Pouch: Packages in the format of pillow pouches were prepared with sidewalls having the following laminated film structure: 90 ga OPE/ink/adhesive/2.0 mil white LLDPE. The sidewall film thickness was 73.7 microns. Package dimensions were 20.32 cm by 22.54 cm. The packages included 67, 400 microns laser perforations in the top portion of the package
Form-Fill-Seal Pouch: Packages in the format of stand-up form-fill seal pouch pouches were prepared with a sidewall having the following laminated film structure, 90 ga OPE/ink/adhesive/2.0 mil white LLDPE and a patch. The patch was a die cut label and included a polypropylene structure. The patch structure was 65 ga PP/adhesive/polyvinylidene chloride (PVDC)/2.0 mil PP with an acrylic-based adhesive coating applied at 13.8 lbs/rm onto the 65 ga PP surface. The patch was adhered on the sealant surface of the sidewall. The patch occupied 100% of the bottom portion of the package and was independent of the package seal. The patch included a thermal conductivity value of approximately 0.22 W/m·K. The sidewall film thickness was 73.7 microns. The patch thickness was 73.7 microns. Package dimensions were 18.73 cm (h) by 20.32 cm (w) (7.375 inches by 8.000 inches). The packages included a 3.81 cm (1.50 inch) wide gusset. The packages included 67, 400 micron laser perforations in the top portion of the package.
Comparative Form-Fill-Seal Pouch: Packages in the format of stand-up form-fill seal pouch pouches were prepared with a sidewall having the following laminated film structure: 90 ga OPE/ink/adhesive/2.0 mil white LLDPE. The sidewall film thickness was 73.7 microns. Package dimensions were 20.32 cm by 22.54 cm. The packages included a 3.81 cm (1.50 inch) wide gusset. The packages included 67, 400 micron laser perforations in the top portion of the package.
Exterior Package Temperature Results: the temperature of the exterior of the bottom for all packages exceeded 62.8° C. (145° F.).
Distortion, Warping and Failure Results: the rating scale shown in TABLE 1 was used to assess defects in the microwaved packages. The entire package was observed for defects, particularly where product contacted the package sidewall. Four main defects reported included holes, wrinkles, blistering, and stretching. The rating scale indicates the severity of the defects on a scale from 0 to 5 where 0 indicated no defects observed and 5 indicated that there were severe defects and/or a high number of defects.
TABLE 2 includes the rating results from the pillow pouch packages.
TABLE 3 includes an explanation of the defects observed for the pillow pouch package samples.
Pillow pouch package results indicate that the samples that include a patch have significantly lower defect average ratings than the comparative samples, which are further supported by the observations noted in TABLE 3.
TABLE 4 includes the rating results from the form-fill-seal pouch packages.
TABLE 5 includes an explanation of the defects observed for the pillow pouch package samples.
Form-fill-seal pouch package results indicate that the samples that include a patch have significantly lower defect average ratings than the comparative samples, which are further supported by the observations noted in TABLE 5.
TABLE 6 includes the average among the sample group of the defect average rating. The average of the average defect ratings for pillow pouch packages including a patch (Samples 1-5) was 1.75. The average of the average defect ratings for pillow pouch packages without a patch (Comparative Samples 1-2) was 3.75. The average of the average defect ratings for form-fill-seal pouch packages including a patch (Samples 1-5) was 1.45. The average of the average defect ratings for form-fill-seal pouch packages without a patch (Comparative Samples 1-2) was 3.125.
The overall comparative sample (packages without a patch) average defect rating was 3.44. The overall package sample (packages including a patch) average defect rating was 1.6. The defect rating was reduced by 50% when a patch is present in the package.
Thermal Strain Value: Thermal strain value curves of the sidewall film (monopolymer-based film) and the patch (heat-resistant polymer-based film) used to make the previously described pillow pouch and form-fill-seal pouch package examples are shown in
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/018763 | 3/3/2022 | WO |
