Patent Application
20250196426
The subject matter disclosed herein relates to a food packaging article and method of manufacturing a food packaging article.
Fiber based trays provide a more sustainable alternative to polystyrene-based trays. Fiber based trays are susceptible to damage from moisture. As moisture from food product seeps into the fiber-based tray the moisture causes the tray to become soft. This can result in tears, leaks or a lack of integrity. Thus, the use of fiber-based trays for packaging food articles that will survive the packaging process and maintain integrity throughout the shelf life of the food product provides a challenge.
Fluff pulp and fiber made from a dry airlaid process are used to produce absorbent materials. Both are readily available. However, the absorbent properties of fiber materials are a hinderance to a food packaging article since the absorbing material would allow moisture to seep into the food packaging, thereby compromise the integrity of the package.
Other fiber-based solutions have been used for short term use of food products. For example take out containers and fiber-based plates and bowls. However, these solutions typically only maintain their integrity of the package for a short time once a moisture containing food product comes in contact. These solutions are not suitable for food packaging applications.
Food packaging processes, such as with the use of overwrap and shrink film, creates forces on the tray. The force can be strong enough to deform a fiber-based tray resulting in damage to the package integrity and unsightly appearance.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
A fiber based moisture resistant packaging article and a method of manufacturing a packaging article. The packaging article being thermoformed from a multi-layer web. The multi-layer web having an upper film portion that is a multi-layer film; a lower film portion; and a compressed fiber core disposed between the upper film portion and the lower film portion. The total film content of the thermoformed food packaging article is less than 15 wt % as compared to the total weight of thermoformed food packaging article.
An advantage that may be realized in the practice of some disclosed embodiments of the packaging article is a packaging article with sufficient moisture barrier and rigidity to be suitable to package food products, including food products having moisture content. The packaging article can survive the food packaging process, shipping and retail display throughout the shelf life of the food product.
In one exemplary embodiment, a thermoformed food packaging article is disclosed. The thermoformed food packaging article comprises a multi-layer web. The multi-layer web having an upper film portion that is a multi-layer film; a lower film portion; and a compressed fiber core disposed between the upper film portion and the lower film portion. The total film content of the thermoformed food packaging article is less than 15 wt % as compared to the total weight of thermoformed food packaging article.
In another exemplary embodiment, a food packaging article is disclosed. The food packaging article having a tray. The tray being made from a multi-layer web having an upper film portion that is a multi-layer film; a lower film portion; and a compressed fiber core disposed between the upper film portion and the lower film portion. The total film content of the tray is less than 15 wt % as compared to the total weight of tray. The food packaging article further including a food product situated on the upper film portion. A polymeric film is situated over the food product and in contact with the upper periphery of the tray, sealing the food product within.
In yet another exemplary embodiment, a method of making a food packaging article is disclosed. The method comprises the steps of: providing a compressed fiber web, the compressed fiber web having a first surface and a second surface; applying an upper film to the first surface of the compressed fiber web, the upper film being a multi-layer film; applying a lower film to the second surface of the compressed fiber web; thermoforming the compressed fiber web, upper film and lower film into a three-dimensional thermoformed food packaging article. The total film content of the thermoformed food packaging article is less than 15 wt % as compared to the total weight of thermoformed food packaging article.
This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.
So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which:
A packaging article formed by thermoforming a multi-layer web. The multi-layer web being a combination of an unwoven fiber web and films disposed on either side. Heat and pressure are applied to the multi-layer web in tooling to form a packaging article. Packaging articles, include but are not limited to trays.
Airlaying, also sometimes referred to as air forming is a method of forming a web by mixing fibers with air to fluff the fibers. The air fiber mixture is then deposited on a moving web such as a paper membrane, thin film, belt, wire, or screen. In some cases the air fluff mixture has sufficient inter-fiber strength to be transported without the need for a moving support web. Pressure differences and vacuums may be utilized to help the moving web keep its shape. The fibers in the airlaying process or transported and formed in their dry state, without the need for excess moisture or water. This is a distinction from typical wetlaid processes. Airlaying is often used to make absorbent fluff pulp, the type often used in absorbent materials such as diapers.
Fibers are readily available, repulpable and compostable, making their use desirable for sustainability. The unwoven fiber web is a sustainable product. Unwoven fibers, such as natural fibers are provided from fluff pulp or formed into web or sheets via a dry air laid process. Fluff pulp is commercially available from a number of supplies and is well known. Typically fluff pulp and dry airlaid fibers have a moisture content of 5-10%. The low moisture content eliminates the need for additional drying processes. An advantage of the dry air laid process is that materials can start with standard pulp fibers in bulk or in roll form. The pulp fibers are hammermilled and vacuum conveyed through a forming head to create a non-woven web. The hammermill can be designed to defiberizer the fluff pulp while limiting destruction of the fibers. For example, if the fluff pulp has a fiber length of about 2.8 mm the fiber exiting the hammermill will also have a fiber length of about 2.8 mm.
Fibers include, but are not limited to, virgin cellulose-based fibers, recycled fibers, such as paper fibers, craft paper, textiles, wood-based fibers, cotton, linen, hemp, sugar cane or grains. Fibers may be untreated or treated with additional materials to enhance properties of the web.
The compressed fiber core is made from a fiber based material. The fiber based material can be provided as a roll or sheet of fluff pulp material or may be made from an airlaid process. Fluff pulp is commercially and readily available. The first step of the airlaid process is the fiberization process where pulp material, such as fluff pulp is fiberized before the actual air laid process. Pulp material may be provided in a bale, sheet or a roll. The pulp material is fed into a defibrator such as a hammermill, which fiberizes the pulp material into loose fibers by small hammers that rotate at high speed to separate the pulp into loose fibers.
The loose fibers are then then transported to a web forming system. In certain processes the loose fibers are sifted through a coarse screen and deposited with the aid of a vacuum onto a forming wire or substrate below. In other processes, the loose fibers pass through a series of holes or slots in a large cylinder that spans the width of the forming wire. In both options, the sheet of loose fibers is kept in place by a vacuum system that can be located below the forming wire to form an unwoven fiber web. Binders and other additives can be used to further aid in forming.
In embodiments a supporting layer is included on the top, the bottom or both the top and bottom of the unwoven fiber web. The supporting layer(s) aid in the handling of the web. In an embodiment the supporting layer(s) are a fiber based tissue.
The loose fibers may be blown, or vacuum pulled onto a first supporting layer. A second supporting layer creates a three-layer structure that is compacted to form an airlaid web. Techniques for generating an airlaid web are known to those skilled in the art. For example, web formation through rotating forming drums and needle rollers. The description herein is one such method. Variations of forming an airlaid web will be understood to those skilled in the art to form the compressed fiber core.
In embodiments the compressed fiber core has a basis weight of between any of the following ranges, 300 to 1100 grams per square meter (gsm), 350 to 900 gsm, 400 to 700 gsm, 450 to 500 gsm measured in accordance with ASTM D-3776 with the sample size being adjusted to a 7 cm by 7 cm square. In embodiments the compressed fiber core has a basis weight of less than any of 1100 gsm, 1000, gsm, 900 gsm, 800, gsm, 700 gsm, 600 gsm, or 500 gsm measured in accordance with ASTM D-3776 with the sample size being adjusted to a 7 cm by 7 cm square.
In embodiments in which the fiber is made from an airlaid web, binders may be applied. Suitable binders include but are not limited to starch, spray binder polymers, dispersions, sol-gel, natural wax (aqueous or 100% solid), polymer latex, polyvinyl acetate, hot melt adhesive coatings, starch-wax emulsions, and blends thereof. Typically, binders are applied in an amount of 20 wt % or less.
Turning now to
Turning now to
Any, some, or all of the heated nips may be heated. Sufficient heat and pressure can improve the adhesion of the films to the compressed fiber web. Since the structure will later be thermoformed, the adhesion need not be permanent or overly strong, as the thermoforming process will result in better adhesion. In embodiments, at least one of the heated nips is heated to a temperature of between 80-120° C. In embodiments, the multi-layer web 375 instead of being wound up, is instead advanced to a thermoforming process.
While the upper and lower films are depicted in
The upper film is disposed onto the top surface of the compressed fiber web. The upper film being a multi-layer structure. The upper film provides water, moisture, grease, oil, or oxygen resistance properties to the compressed fiber web. Without such properties, the compressed fiber web would not be suitable for food packaging applications.
The upper multi-layer film described herein includes at least one food contact layer, at least one barrier layer and at least one fiber bonding layer allowing the film to be bonded to the compressed fiber web. The films further include at least one barrier layer to restrict fluid from permeating through the film. The films may further include additional layers, for example to add bulk, provide functionality, abuse resistance, printing capability or to act as a tie layer.
As used herein, the term “film” is inclusive of plastic web, regardless of whether it is film or sheet. The film can have a thickness of 0.25 mm or less, or a thickness of from 0.5 to 30 mils, or from 0.5 to 15 mils, or from 1 to 10 mils, or from 1 to 8 mils, or from 1.1 to 7 mils, or from 1.2 to 6 mils, or from 1.3 to 5 mils, or from 1.5 to 4 mils, or from 1.6 to 3.5 mils, or from 1.8 to 3.3 mils, or from 2 to 3 mils, or from 1.5 to 4 mils, or from 0.5 to 1.5 mils, or from 1 to 1.5 mils, or from 0.7 to 1.3 mils, or from 0.8 to 1.2 mils, or from 0.9 to 1.1 mils.
The multi-layer films described herein may comprise at least, and/or at most, any of the following numbers of layers: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15. As used herein, the term “layer” refers to a discrete film component which is substantially coextensive with the film and has a substantially uniform composition. Where two or more directly adjacent layers have essentially the same composition, then these two or more adjacent layers may be considered a single layer for the purposes of this application. In an embodiment, the multi-layer film utilizes microlayers. A microlayer section may include between 10 and 1,000 microlayers in each microlayer section.
Below are some examples of combinations in which the alphabetical symbols designate the film layers. Where the multi-layer film representation below includes the same letter more than once, each occurrence of the letter may represent the same composition or a different composition within the class that performs a similar function.
All compositional percentages used herein are presented on a “by weight” basis, unless designated otherwise.
The food contact layer of the upper multi-layer film functions as the food contact layer and in embodiments as the seal layer in which another film, such as a lidding film, can be sealed thereto. As used herein, the phrases “seal layer”, “sealing layer”, “heat seal layer”, and “sealant layer”, refer to an outer layer, or layers, involved in the sealing of the multi-layer film to, another film, and/or another article which is not a film.
Heat seal layers include thermoplastic polymers such as thermoplastic polyolefins and ionomers. In embodiments, polymers for the sealant layer include homogeneous ethylene/alpha-olefin copolymer, heterogeneous ethylene/alpha-olefin copolymer, ethylene homopolymer, ionomer and ethylene/vinyl acetate copolymer. In some embodiments, the heat seal layer can comprise a polyolefin, particularly an ethylene/alpha-olefin copolymer. For example, a polyolefin having a density of from 0.88 g/cc to 0.917 g/cc, or from 0.90 g/cc to 0.917 g/cc, or less than 0.92 g/cc. More particularly, the seal layer can comprise at least one member selected from the group consisting of high density polyethylene, linear low density polyethylene, medium density polyethylene, low density polyethylene, very low density polyethylene, homogeneous ethylene/alpha-olefin copolymer, and polypropylene. “Polymer” herein refers to homopolymer, copolymer, terpolymer, etc. “Copolymer” herein includes copolymer, terpolymer, etc.
As used herein, the term “copolymer” refers to polymers formed by the polymerization of reaction of at least two different monomers. For example, the term “copolymer” includes the co-polymerization reaction product of ethylene and an-olefin, such as 1-octene. The term “copolymer” is also inclusive of, for example, the co-polymerization of a mixture of ethylene, propylene, 1-propene, 1-butene, 1-hexene, and 1-octene. As used herein, a copolymer identified in terms of a plurality of monomers, e.g., “propylene/ethylene copolymer,” refers to a copolymer in which either a monomer may copolymerize in a higher weight or molar percent than the other monomer or monomers. However, the first listed monomer generally polymerizes in a higher weight percent than the second listed monomer.
As used herein, the term “polyolefin” refers to olefin polymers and copolymers, especially ethylene and propylene polymers and copolymers, and to polymeric materials having at least one olefinic comonomer. Polyolefins can be linear, branched, cyclic, aliphatic, aromatic, substituted, or unsubstituted. Included in the term polyolefin are homopolymers of olefin, copolymers of olefin, copolymers of an olefin and a non-olefinic comonomer copolymerizable with the olefin, such as vinyl monomers, modified polymers of the foregoing, and the like. Modified polyolefins include modified polymers prepared by copolymerizing the homopolymer of the olefin or copolymer thereof with an unsaturated carboxylic acid, e.g., maleic acid, fumaric acid or the like, or a derivative thereof such as the anhydride, ester metal salt or the like. It could also be obtained by incorporating into the olefin homopolymer or copolymer, an unsaturated carboxylic acid, e.g., maleic acid, fumaric acid or the like, or a derivative thereof such as the anhydride, ester metal salt or the like. In an embodiment, the heat seal layer is mainly composed of polyolefin. In an embodiment, the heat seal layer has a total polyolefin content of from 90 to 99 wt % based on the total composition of the heat seal layer.
Ethylene homopolymer or copolymer refers to ethylene homopolymer such as low density polyethylene; ethylene/alpha olefin copolymer such as those defined hereinbelow; and other ethylene copolymers such as ethylene/vinyl acetate copolymer; ethylene/alkyl acrylate copolymer; or ethylene/(meth) acrylic acid copolymer. Ethylene/alpha-olefin copolymer herein refers to copolymers of ethylene with one or more comonomers selected from C4 to C10 alpha-olefins such as butene-1, hexene-1, octene-1, etc. in which the molecules of the copolymers comprise long polymer chains with relatively few side chain branches arising from the alpha-olefin which was reacted with ethylene. This molecular structure is to be contrasted with conventional high pressure low or medium density polyethylenes which are highly branched with respect to ethylene/alpha-olefin copolymers and which high pressure polyethylenes contain both long chain and short chain branches. Ethylene/alpha-olefin copolymers include one or more of the following: 1) high density polyethylene, for example having a density greater than 0.94 g/cm3, 2) medium density polyethylene, for example having a density of from 0.93 to 0.94 g/cm3, 3) linear medium density polyethylene, for example having a density of from 0.926 to 0.94 g g/cm3, 4) low density polyethylene, for example having a density of from 0.915 to 0.939 g/cm3, 5) linear low density polyethylene, for example having a density of from 0.915 to 0.935 g/cm3, 6) very-low or ultra-low density polyethylene, for example having density below 0.915 g/cm3, and homogeneous ethylene/alpha-olefin copolymers. Homogeneous ethylene/alpha-olefin copolymers include those having a density of less than about any of the following: 0.925, 0.922, 0.92, 0.917, 0.915, 0.912, 0.91, 0.907, 0.905, 0.903, 0.90, and 0.86 g/cm3. Unless otherwise indicated, all densities herein are measured according to ASTM D1505.
As used herein, the phrase “modified polymer,” as well as more specific phrases such as “modified ethylene vinyl acetate copolymer,” and “modified polyolefin” refer to such polymers having an anhydride functionality, as defined immediately above, grafted thereon and/or copolymerized therewith and/or blended therewith. Preferably, such modified polymers have the anhydride functionality grafted on or polymerized therewith, as opposed to merely blended therewith.
In general, the ethylene/alpha-olefin copolymer comprises a copolymer resulting from the copolymerization of from about 80 to 99 weight percent ethylene and from 1 to 20 weight percent alpha-olefin. Preferably, the ethylene alpha-olefin copolymer comprises a copolymer resulting from the copolymerization of from about 85 to 95 weight percent ethylene and from 5 to 15 weight percent alpha-olefin.
As used herein, the phrase “heterogeneous polymer” refers to polymerization reaction products of relatively wide variation in molecular weight and relatively wide variation in composition distribution, i.e., typical polymers prepared, for example, using conventional Ziegler-Natta catalysts. Heterogeneous copolymers typically contain a relatively wide variety of chain lengths and comonomer percentages. Heterogeneous copolymers have a molecular weight distribution (Mw/Mn) of greater than 3.0.
As used herein, the phrase “homogeneous polymer” refers to polymerization reaction products of relatively narrow molecular weight distribution and relatively narrow composition distribution. Homogeneous polymers are useful in various layers of the multi-layer film. Homogeneous polymers are structurally different from heterogeneous polymers, in that homogeneous polymers exhibit a relatively even sequencing of comonomers within a chain, a mirroring of sequence distribution in all chains, and a similarity of length of all chains, i.e., a narrower molecular weight distribution. Furthermore, homogeneous polymers are typically prepared using metallocene, or other single-site type catalysis, rather than using Ziegler Natta catalysts. Homogeneous polymers have a molecular weight distribution (Mw/Mn) of less than 3.0 More particularly, homogeneous ethylene/alpha-olefin copolymers may be characterized by one or more methods known to those of skill in the art, such as molecular weight distribution (Mw/Mn), composition distribution breadth index (CDBI), narrow melting point range, and single melt point behavior. The molecular weight distribution (Mw/Mn), also known as “polydispersity,” may be determined by gel permeation chromatography. In some embodiments, the homogeneous ethylene/alpha-olefin copolymers have an Mw/Mn of less than 2.7; in another embodiment from about 1.9 to 2.5; and it yet another embodiment, from about 1.9 to 2.3. The composition distribution breadth index (CDBI) of such homogeneous ethylene/alpha-olefin copolymers will generally be greater than about 70 percent. The CDBI is defined as the weight percent of the copolymer molecules having a comonomer content within 50 percent (i.e., plus or minus 50%) of the median total molar comonomer content. The CDBI of linear polyethylene, which does not contain a comonomer, is defined to be 100%. The Composition Distribution Breadth Index (CDBI) is determined via the technique of Temperature Rising Elution Fractionation (TREF). CDBI determination clearly distinguishes homogeneous copolymers (i.e., narrow composition distribution as assessed by CDBI values generally above 70%) from VLDPEs available commercially which generally have a broad composition distribution as assessed by CDBI values generally less than 55%. TREF data and calculations therefrom for determination of CDBI of a copolymer is readily calculated from data obtained from techniques known in the art, such as, for example, temperature rising elution fractionation as described, for example, in Wild et. al., J. Poly. Sci. Poly. Phys. Ed., Vol. 20, p.441 (1982). In some embodiments, homogeneous ethylene/alpha-olefin copolymers have a CDBI greater than about 70%, i.e., a CDBI of from about 70% to 99%. In general, homogeneous ethylene/alpha-olefin copolymers useful in the present invention also exhibit a relatively narrow melting point range, in comparison with “heterogeneous copolymers”, i.e., polymers having a CDBI of less than 55%. In an embodiment, the homogeneous ethylene/alpha-olefin copolymers exhibit an essentially singular melting point characteristic, with a peak melting point (Tm), as determined by Differential Scanning Colorimetry (DSC), of from about 60° C. to 105° C. In an embodiment, the homogeneous copolymer has a DSC peak Tm of from about 80° C. to 100° C. As used herein, the phrase “essentially single melting point” means that at least about 80%, by weight, of the material corresponds to a single Tm peak at a temperature within the range of from about 60° C. to 105° C., and essentially no substantial fraction of the material has a peak melting point in excess of about 115° C., as determined by DSC analysis. DSC measurements are made on a Perkin Elmer System 7 Thermal Analysis System. Melting information reported are second melting data, i.e., the sample is heated at a programmed rate of 10° C./min to a temperature below its critical range. The sample is then reheated (2nd melting) at a programmed rate of 10° C./min.
A homogeneous ethylene/alpha-olefin copolymer can, in general, be prepared by the copolymerization of ethylene and any one or more alpha-olefin. In certain embodiments, the alpha-olefin is a C3-C20 alpha-monoolefin, a C4-C12 alpha-monoolefin, a C4-C8 alpha-monoolefin. In an embodiment, the alpha-olefin copolymer comprises at least one member selected from the group consisting of butene-1, hexene-1, and octene-1, i.e., 1-butene, 1-hexene, and 1-octene, respectively. In an embodiment, the alpha-olefin copolymer comprises octene-1, and/or a blend of hexene-1 and butene-1. In another embodiment, the alpha-olefin copolymer comprises a blend of at least two of octene-1, hexene-1 and butene-1.
The thickness of the food contact layer as a percentage of the total thickness of the upper multi-layer film may be less that any of the following values: 50%, 40%, 30%, 25%, 20%, 15%, 10%, and 5%; and may range between any of the forgoing values (e.g., from 10% to 30%).
In an embodiment, the upper multi-layer film comprises a barrier layer. As used herein, the term “barrier”, and the phrase “barrier layer”, as applied to films and/or film layers, are used with reference to the ability of a film or film layer to serve as a barrier to one or more gases. Oxygen transmission rate is one method to quantify the effect of a barrier layer. As used herein, the term “oxygen transmission rate” refers to the oxygen transmitted through a film in accordance with ASTM D3985 “Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor,” which is hereby incorporated, in its entirety, by reference thereto.
The barrier layers include at least 50, 60, 70, 80, 90, or 95% weight of the layer of barrier polymers chosen from ethylene-vinyl alcohol copolymer, polyvinyl alcohol copolymer, polyvinylidene chloride, polyamides or blends thereof. In an embodiment the barrier layers are substantially all barrier polymers. The ethylene content of the ethylene-vinyl alcohol copolymer has an effect on the processability of multi-layer films and also has an effect on oxygen transmission rate. Generally, lower ethylene content results in a film that has a lower orientability, and may not be processable at certain orientation ratios. A higher ethylene content generally raises the oxygen transmission rate properties.
In other embodiments, ethylene-vinyl alcohol copolymers may have an ethylene content of about 38 mole %, or at least about any of the following values: 20%, 25%, 30%, 38%, 44% and 48% all mole percent. In embodiments, ethylene-vinyl alcohol copolymers may have an ethylene content of at most about any of the following values: 50%, 48%, 44%, 40%, and 38% all mole percent. In embodiments, the ethylene-vinyl alcohol copolymer or blend of ethylene-vinyl alcohol copolymers resulting in an ethylene content of between 27-48 mol %. Ethylene-vinyl alcohol copolymers may include saponified or hydrolyzed ethylene/vinyl acetate copolymers, such as those having a degree of hydrolysis of at least about any of the following values: 50%, 85%, 95%, 95%. Ethylene-vinyl alcohol copolymers may have an ethylene content ranging from about 20 mole percent to about 50 mole percent. Exemplary ethylene-vinyl alcohol copolymers include those having ethylene contents of 27, 29, 32, 35, 38, 44, 48 and 50 mole % and blends thereof.
“Polyamide” herein refers to polymers having amide linkages along the molecular chain, and preferably to synthetic polyamides such as nylons. Furthermore, such term encompasses both polymers comprising repeating units derived from monomers, such as caprolactam, which polymerize to form a polyamide, as well as polymers of diamines and diacids, and copolymers of two or more amide monomers, including nylon terpolymers, sometimes referred to in the art as “copolyamides”. Useful polyamides include those of the type that may be formed by the polycondensation of one or more diamines with one or more diacids and/or of the type that may be formed by the polycondensation of one or more amino acids. Useful polyamides include aliphatic polyamides and aliphatic/aromatic polyamides.
Representative aliphatic diamines for making polyamides include those having the formula:
H2N(CH2)nNH2
Representative diacids for making polyamides include dicarboxylic acids, which may be represented by the general formula:
HOOC—Z—COOH
The polycondensation reaction product of one or more or the above diamines with one or more of the above diacids may form useful polyamides. Representative polyamides of the type that may be formed by the polycondensation of one or more diamines with one or more diacids include aliphatic polyamides such as poly(hexamethylene adipamide) (“nylon-6,6”), poly(hexamethylene sebacamide) (“nylon-6,10”), poly(heptamethylene pimelamide) (“nylon-7,7”), poly(octamethylene suberamide) (“nylon-8,8”), poly(hexamethylene azelamide) (“nylon-6,9”), poly(nonamethylene azelamide) (“nylon-9,9”), poly(decamethylene azelamide) (“nylon-10,9”), poly(tetramethylenediamine-co-oxalic acid) (“nylon-4,2”), the polyamide of n-dodecanedioic acid and hexamethylenediamine (“nylon-6,12”), the polyamide of dodecamethylenediamine and n-dodecanedioic acid (“nylon-12,12”).
Representative aliphatic/aromatic polyamides include poly(tetramethylenediamine-co-isophthalic acid) (“nylon-4,I”), polyhexamethylene isophthalamide (“nylon-6,I”), poly(2,2,2-trimethyl hexamethylene terephthalamide), poly(m-xylylene adipamide) (“nylon-MXD,6”), poly(p-xylylene adipamide), poly(hexamethylene terephthalamide), poly(dodecamethylene terephthalamide), and polyamide-MXD,I.
Representative polyamides of the type that may be formed by the polycondensation of one or more amino acids include poly(4-aminobutyric acid) (“nylon-4”), poly(6-aminohexanoic acid) (“nylon-6” or “poly(caprolactam)”), poly(7-aminoheptanoic acid) (“nylon-7”), poly(8-aminooctanoic acid) (“nylon-8”), poly(9-aminononanoic acid) (“nylon-9”), poly(10-aminodecanoic acid) (“nylon-10”), poly(11-aminoundecanoic acid) (“nylon-11”), and poly(12-aminododecanoic acid) (“nylon-12”).
Representative copolyamides include copolymers based on a combination of the monomers used to make any of the foregoing polyamides, such as, nylon-4/6, nylon-6/9,caprolactam/hexamethylene adipamide copolymer (“nylon-6,6/6”), hexamethylene adipamide/caprolactam copolymer (“nylon-6/6,6”), trimethylene adipamide/hexamethylene azelaiamide copolymer (“nylon-trimethyl 6,2/6,2”), hexamethylene adipamide-hexamethylene-azelaiamide caprolactam copolymer (“nylon-6,6/6,9/6”), hexamethylene adipamide/hexamethylene-isophthalamide (“nylon-6,6/6,I”), hexamethylene adipamide/hexamethyleneterephthalamide (“nylon-6,6/6,T”), nylon-6,T/6,I, nylon-6/MXD,T/MXD,I, nylon-6,6/6,10, and nylon-6,1/6,T.
Polyamides also include modifications and blends of those discussed above. “Polyamide” further includes amorphous, crystalline or partially crystalline, aromatic or partially aromatic polyamides.
In embodiments the barrier layer is less than 15 wt % of the upper multi-layer film. In other embodiments, the barrier layer is less than 10 wt % of the multi-layer film. In yet other embodiments, the barrier layer is less than 5 wt % of the multi-layer film.
The upper multi-layer film may include a fiber bonding layer. The primary function of the fiber bonding layer being to bond the multi-layer film to the compressed fiber web. The bonding layer including materials to that function to seal as discussed above in regards to heat seal layers. In embodiments, the fiber bonding layer includes materials with a low seal initiation temperature. In embodiments, the fiber bonding layer includes materials having a seal initiation temperature of less than 120° C., 110° C., 100° C., 90° C. or 80° C. In embodiments, the fiber bonding layer includes ethylene/vinyl acetate copolymers, ionomers or blends thereof.
The thickness of the fiber bonding layer as a percentage of the total thickness of the upper multi-layer film may be less that any of the following values: 50%, 40%, 30%, 25%, 20%, 15%, 10%, and 5%; and may range between any of the forgoing values (e.g., from 10% to 30%).
The upper multi-layer film may comprise one or more intermediate layers, such as a tie layer. In addition to a first intermediate layer, the film may comprise a second intermediate layer. “Intermediate” herein refers to a layer of a multi-layer film which is between an outer layer and an inner layer of the film. “Inner layer” herein refers to a layer which is not an outer or surface layer, and has both of its principal surfaces directly adhered to another layer of the film. “Outer layer” herein refers to any film layer of film having less than two of its principal surfaces directly adhered to another layer of the film. All multi-layer films have two, and only two, outer layers, each of which has a principal surface adhered to only one other layer of the multi-layer film. In monolayer films, there is only one layer, which, of course, is an outer layer in that neither of its two principal surfaces are adhered to another layer of the film. “Outer layer” also is used with reference to the outermost layer of a plurality of concentrically arranged layers of a seamless tubing, or the outermost layer of a seamed film tubing.
In embodiments with multiple intermediate layers, the composition, thickness, and other characteristics of a second intermediate layer may be substantially the same as any of those of a first intermediate layer, or may differ from any of those of the first intermediate layer.
An intermediate layer may be, for example, between the food contact layer and the barrier layer. An intermediate layer may be directly adjacent the food contact layer, so that there is no intervening layer between the intermediate and heat seal layers. An intermediate layer may be directly adjacent the barrier layer, so that there is no intervening layer between the intermediate and barrier layers. An intermediate layer may be directly adjacent both the food contact layer and the barrier layer. An intermediate layer may be, for example, between the fiber bonding layer and the barrier layer. An intermediate layer may be directly adjacent the fiber bonding layer, so that there is no intervening layer between the intermediate and fiber bonding layers. An intermediate layer may be directly adjacent the barrier layer, so that there is no intervening layer between the intermediate layer and barrier layers. An intermediate layer may be directly adjacent both the fiber bonding layer and the barrier layer.
The thickness of the intermediate layer as a percentage of the total thickness of the upper multi-layer film may be at least about, and/or at most about, any of the following: 1%, 3%, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%.
An intermediate layer may comprise one or more of any of the tie polymers described herein in at least about, and/or at most about, any of the following amounts: 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 90%, 95%, and 99.5%, by weight of the layer.
A tie layer refers to an internal film layer that adheres two layers to one another. Useful tie polymers include thermoplastic polymers that may be compatible both with the polymer of one directly adjacent layer and the polymer of the other directly adjacent layer. Such dual compatibility enhances the adhesion of the tied layers to each other. Tie layers can be made from polyolefins such as modified polyolefin, ethylene/vinyl acetate copolymer, modified ethylene/vinyl acetate copolymer, and homogeneous ethylene/alpha-olefin copolymer. Typical tie layer polyolefins include anhydride modified grafted linear low density polyethylene, anhydride grafted (i.e., anhydride modified) low density polyethylene, anhydride grafted very low density polyethylene, anhydride grafted polypropylene, anhydride grafted methyl acrylate copolymer, anhydride grafted butyl acrylate copolymer, homogeneous ethylene/alpha-olefin copolymer, and anhydride grafted ethylene/vinyl acetate copolymer.
The upper multi-layer film may comprise one or more other layers such as a bulk layer. Bulk layers are often a layer or layers of a film that can increase the abuse resistance, toughness, or modulus of a film. In some embodiments the film comprises a bulk layer that functions to increase the abuse resistance, toughness, and/or modulus of the film. Bulk layers generally comprise polymers that are inexpensive relative to other polymers in the film that provide some specific purpose unrelated to abuse-resistance, modulus, etc. In an embodiment, the bulk layer comprises at least one member selected from the group consisting of: ethylene/alpha-olefin copolymer, ethylene homopolymer, propylene/alpha-olefin copolymer, propylene homopolymer, and combinations thereof.
The thickness of the bulk layer as a percentage of the total thickness of the upper multi-layer film may be at least about, and/or at most about, any of the following: 1, 3, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45, and 50 percent.
In embodiments the upper multi-layer film includes at least five discrete layers. In embodiments the upper multi-layer film includes a food contact layer, a barrier layer, a fiber bonding layer, a first tie layer disposed between the food contact layer and the barrier layer and a second tie layer disposed between the barrier layer and the fiber bonding layer. In an embodiment, the upper multi-layer film has five layers with the first tie layer being in direct contact with the food contact layer and the barrier layer. The second tie layer being in direct contact with the barrier layer and the fiber bonding layer.
In a first aspect, the upper multi-layer film includes at least five discrete layers. The first layer being a food contact layer has at least any of 50 wt %, 60 wt %, 70 wt %, 80 wt %, 90 wt % or 95 wt % in relation to the food contact layer of an ethylene homopolymer or copolymer. In embodiments the ethylene homopolymer or copolymer is selected from high density polyethylene, medium density polyethylene, linear medium density polyethylene, low density polyethylene, linear low density polyethylene, ultra-low density polyethylene, homogeneous ethylene/alpha-olefin copolymers and blends thereof.
In the first aspect the upper multi-layer film further includes a barrier layer having at least any of 50 wt %, 60 wt %, 70 wt %, 80 wt %, 90 wt % or 95 wt % of ethylene-vinyl alcohol copolymer, polyvinyl alcohol copolymer, polyamides or blends thereof. The first aspect includes a first and second tie layer, each of which is predominantly anhydride modified grafted linear low density polyethylene, anhydride grafted low density polyethylene, anhydride grafted very low density polyethylene, anhydride grafted methyl acrylate copolymer, anhydride grafted ethylene/vinyl acetate copolymer, or blends thereof.
The first aspect further includes a fiber bonding layer, the fiber bonding layer has at least any of 50 wt %, 60 wt %, 70 wt %, 80 wt %, 90 wt % or 95 wt % in relation to the fiber bonding layer of an ethylene/vinyl acetate copolymer, ethylene homopolymer or copolymer, or blends thereof. In an embodiment, the fiber bonding layer is predominantly ethylene/vinyl acetate copolymer. In other embodiments the fiber bonding layer is predominantly is an ethylene homopolymer or copolymer is selected from high density polyethylene, medium density polyethylene, linear medium density polyethylene, low density polyethylene, linear low density polyethylene, ultra-low density polyethylene, homogeneous ethylene/alpha-olefin copolymers and blends thereof.
The lower film is disposed onto the bottom surface of the compressed fiber web (the surface opposite that of the upper film). The lower film provides moisture resistance properties to the compressed fiber web. Without such properties, the compressed fiber web would not be suitable for food packaging applications. The lower film further seals to the compressed fiber web.
In one embodiment the lower film is a multi-layer film. Various layers of multi-layer films are discussed herein and are suitable for the lower film. In another embodiment the lower film is a monolayer film.
In embodiments, the lower film is primarily made from polyolefins. In some embodiments the lower film includes materials selected from homogeneous ethylene/alpha-olefin copolymer, heterogeneous ethylene/alpha-olefin copolymer, ethylene homopolymer, ionomer, ethylene/vinyl acetate copolymer, polypropylene, biopolymers, and blends thereof. In embodiments, the lower film primarily ethylene homopolymer or copolymer. In other embodiments, the lower film is primarily a biodegradable aliphatic polyester such as polybutylene succinate.
To aid in recyclability, repulpability, compostability or sustainability, the total film content is kept low. In embodiments, the weight of film (such as the sum of the upper and lower films) in the multi-layer web, as compared to the total weight of the multi-layer web is less 15%, or 10%. In embodiments, the low weight of the film results in the total film thickness being less than any of 60 microns, 55 microns, 50 microns, 45 microns or 40 microns.
In some embodiments a binder is deposited onto the fiber material prior to application of the film(s). In embodiments, the binder has moisture resistance properties. Exemplary binders include, but are not limited to sol-gel, natural wax (aqueous or 100% solid), polymer latex, hot melt adhesive coatings, starch-wax emulsions. In embodiments, the coatings are applied to the non-woven web or supporting layer. In embodiments, the coating deposition is applied at any of between 2 and 25 g/m2, between 3 and 20 g/m2, between 4 and 15 g/m2, less than 20 g/m2 or less than 15 g/m2.
Exemplary binders include but are not limited to repulpable hot melt coating available from Henkel, Munzing WU 2800, Munzing WU1512, Solenis PC350, Sun Sys 3007, Fluteshield Sonoco, Naiosol TPW, SX5PW702 Sun Chemical, SYSPW005 Sun Chemical, Epotal Sp 106D, Epotal S 440, Ulterion 535 OPV, Ecoshield, VAP2200R, PK265D, MC95, TopScreen SP200, TopScreen PC350, Cartseal HFU, Jonycryl HPB 1702, Caruba wax.
In embodiments, the tray is repulpable. As used herein, the term “repulpable” means a sample has a fiber yield from the repulpability test as described in the Aug. 16, 2013, revision of the “Voluntary Standard For Repulping and Recycling Corrugated Fiberboard Treated to Improve Its Performance in the Presence of Water and Water Vapor” provided by the Fibre Box Association of Elk Grove Village, Ill which is at least 80% based on the total weight, or 85% based on the bone dry fiber charge to the pulper.
Measuring for repulpability is done in accordance with the requirements of the Aug. 16, 2013, revision of the “Voluntary Standard For Repulping and Recycling Corrugated Fiberboard Treated to Improve Its Performance in the Presence of Water and Water Vapor” provided by the Fibre Box Association of Elk Grove Village, Ill. which is hereby incorporated in its entirety. In this regard, the disclosed food packaging tray can be recyclable in accordance with the requirements of the Aug. 16, 2013, revision of the “Voluntary Standard For Repulping and Recycling Corrugated Fiberboard Treated to Improve Its Performance in the Presence of Water and Water Vapor” provided by the Fibre Box Association of Elk Grove Village, Ill. The tray can be recycled as a single processing stream without requiring separation of materials.
Turning now to
The flat sheet 364 is advanced to the forming section 380. An embodiment of a forming section is shown in more detail in
Turning back now to
The thermoformed packaging article includes an upper film, a lower film and a compressed fiber core. The total thickness of the films being less than any of 60 microns, 55 microns, 50 microns, 45 microns or 40 microns. The total film content of the thermoformed packaging article is less than 15 wt % as compared to the total weight of thermoformed packaging article. The compressed fiber core has a basis weight of between any of the following ranges, 300 to 1100 grams per square meter (gsm), 350 to 900 gsm, 400 to 700 gsm, 450 to 600 gsm measured in accordance with ASTM D-3776 with the sample size being adjusted to a 7 cm by 7 cm square. In embodiments the compressed fiber core has a basis weight of less than any of 1100 gsm, 1000, gsm, 900 gsm, 800, gsm, 700 gsm, 600 gsm, or 500 gsm measured in accordance with ASTM D-3776 with the sample size being adjusted to a 7 cm by 7 cm square.
Once the multi-layer web is formed, the web is then thermoformed into a packaging article. A thermoforming machine utilizes pressure and temperature which provides for hydrogen bonding to create a packaging article. Packaging articles, include but are not limited to trays as shown in
Once the packaging article is formed, a food product is placed in the packaging article. In embodiments, the food product is a moisture containing food product. Moisture containing food products include, but are not limited to meat, fish and certain fruits and vegetables. The moisture containing food products often leave some moisture in the packaging.
In embodiments, the packaging article and food product are overwrapped with a film. The term “overwrap” as used herein refers to a material formed from a film or material that can cover the external surface of all or part of a package. In some embodiments, the overwrap can be provided around a single package, be a sealed lidding film, or be part of a modified atmosphere package. In embodiments, the overwrap is a heat shrinkable film.
In embodiments, package can optionally comprise barrier overwrap that completely or partially covers the package and adheres or clings to itself or to the package. See, for example, U.S. Pat. No. 6,408,598 to Stockley; U.S. Pat. No. 5,663,002 to Schirmer; U.S. Pat. No. 4,759,444 to Barmore; U.S. Pat. No. 5,018,623 to Hrenyo; and U.S Pat. No. 4,818,548 to Cheng, the entire disclosures of which are incorporated herein by reference.
In embodiments, the overwrap film has a free shrink of at least 10%, 20%, 30%, 40% and 50% at 85° C. measured in accordance with ASTM D2732. As used herein, the phrase “free shrink” refers to the percent dimensional change in a 10 cm×10 cm specimen of film, when shrunk at 185° F., with the quantitative determination being carried out according to ASTM D2732 “Standard Test Method for Unrestrained Linear Thermal Shrinkage of Plastic Film and Sheeting.” Unless otherwise indicated, all free shrink values disclosed herein are, of course, “total” free shrink values, which represent a sum of (a) the percent free shrink in the longitudinal (i.e., “machine”) direction dimension and (b) the percent free shrink in transverse direction.
Residual force of the overwrap film generally allows the package to remain taught and gives good presentation of a product therein through the shelf life of the product. In embodiments, the residual force of the overwrap film is at least any of 75, 100, 125, 150, 175 or 200 gram force in either the machine or traverse directions as measured in accordance with residual force test stated herein. In embodiments, the residual force of the overwrap film is at least any of 75, 100, 125, 150, 175 or 200 gram force in both the machine and traverse directions as measured in accordance with residual force test recited herein. In embodiments the overwrap film also exhibits between 10-50 kg/cm2 of shrink tension in either of the machine or traverse directions as measured in accordance with ASTM D2838. In embodiments the overwrap film also exhibits between 10-50 kg/cm2 of shrink tension both the machine and traverse directions as measured in accordance with ASTM D2838. The packaging article being capable of maintaining its shape under these forces and tensions.
Turning now to
The packaging article has a moisture barrier sufficient such that the packaging article maintains its integrity throughout the self-life of the food product. In embodiments, the shelf life being at least 5, 10, 15, 20, 25, 30, 35, 40 or 45 days. The food product will often have moisture and liquid which purges from the food product. The moisture barrier layer protects the fiber material allowing for the packaging article to be suitable for package food products, including moisture containing food products.
All references to (and incorporations by reference of) ASTM protocols are to the most-recently published ASTM procedure as of the priority (i.e., original) filing date of this patent application in the United States Patent Office unless stated otherwise.
This written description uses examples to disclose the invention and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
This application claims priority to U.S. Patent Application Ser. No. 63/323,119, filed Mar. 24, 2022 and entitled “Dry Laid Moisture Resistant Packaging Article And Method Of Manufacture,” the entirety of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2023/016178 | 3/24/2023 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63323119 | Mar 2022 | US |
