WO2019222433A1

WO2019222433A1 - Layered film structures, article made therefrom, and methods for making the same

Info

Publication number: WO2019222433A1
Application number: PCT/US2019/032535
Authority: WO
Inventors: Dan Xu
Original assignee: Exxonmobil Chemical Patents Inc.
Priority date: 2018-05-16
Filing date: 2019-05-15
Publication date: 2019-11-21

Abstract

A layered film structure including, in order: a thermoplastic sealing layer; a tie layer including an ethylene acrylic acid copolymer (EAA) having an acrylic acid content of about 5.5 wt% to about 6.5 wt%, based upon the total weight of the copolymer, a melt index (ASTM D1238-16 at l90°C and 2.16 kg) of about 8.0 g/10 min to about 8.4 g/10 min, and an average long-chain branching factor (LCBf/lOOOTC) as measured by gel permeation chromatography with viscometry (GPC- viscometer) of about 1.0 to about 2.0; and a barrier layer, is provided.

Description

LAYERED FILM STRUCTURES, ARTICLES MADE THEREFROM, AND

METHODS FOR MAKING THE SAME

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit to Serial No. 62/672,337, filed May 16, 2018, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF INVENTION

[0002] This invention relates to a layered film structure including a tie layer comprising an ethylene acrylic acid copolymer (EAA) that, in extrusion coating, can be down gauged while still providing exceptional adhesion performance to the adjacent layers. The invention further relates to a method for manufacturing the layered film structure and use thereof in articles, for example, in aseptic packaging.

BACKGROUND OF THE INVENTION

[0003] Paper-based, single-use, disposable packaging containers for containing liquid foods can be produced from layered film structures. The layered film structure is shaped, filled with liquid foods, and sealed. In one example, a packaging container for milk, juice, or other liquid food is produced by first forming the layered film structure into a tube shape by a longitudinal seal of a longitudinal direction. The liquid food is packed in the packaging material formed by the tube shape. Then, the tube-like packaging material is transversally sealed in the transversal direction of the packaging material and cut at that transverse seal with sufficient sealed portions remaining for each resultant packaging container to be folded into the final packaging container shape.

[0004] The layered film structure typically includes (i) an outer, liquid-tight layer, (ii) a core layer of paper or paperboard that provides structure for the container, (iii) a light- and gas- tight layer (also referred to as a barrier layer), typically, aluminum foil, and (iv) an inner thermoplastic sealing layer with (v) tie layers, as needed, between the foregoing layers to provide good adhesion between the layers. Most often, tie layers are included between the core layer and aluminum foil and between the aluminum foil and the inner thermoplastic sealing layer. Examples of layered film structures include, from outside to inside, low-density polyethylene (LDPE)/paperboard/LDPE/aluminum foil/LDPE(s)/LDPE and LDPE/paperboard/LDPE/aluminum foil/EAA/LDPE. Each LDPE composition in the foregoing examples is typically different. Additionally, the paperboard and/or the outermost layer can be printed on to provide the package labeling.

[0005] Producing the layered film structure typically involves extrusion laminating (A) a first layered film structure comprising the outer, liquid-tight layer and the core layer to (B) a second layered film structure comprising the barrier layer, the corresponding tie layer(s), and the inner thermoplastic sealing layer. The first and second layered film structures are produced on different production lines and then extrusion laminated together with an adhesive like LDPE, which becomes a tie layer between the core layer and the barrier layer.

[0006] The second layered film structure may then be produced by coextruding the corresponding tie layer(s) with the inner thermoplastic sealing layer onto the barrier layer.

[0007] The tie layer(s) between the barrier layer and the inner thermoplastic sealing layer have historically been LDPE. However, a multi-layer LDPE tie layer is often needed to achieve good adhesion between the LDPE inner thermoplastic sealing layer and the aluminum foil layer, so some LDPE layers adhere more effectively to aluminum and others adhere more effectively to the LDPE inner thermoplastic sealing layer. See, for example, U.S. Patent No. 8,007,882. However, the need for tie layers complicates production and increases cost.

[0008] In contrast to LDPE, EAA exhibits better adhesion in a single tie layer than LDPE for adhering an aluminum foil layer to an LDPE inner thermoplastic sealing layer. However, an EAA tie layer is thicker than individual LDPE tie layer(s) due to the extrusion properties of EAA. When too thin of an EAA tie layer is applied, the EAA tie layer breaks and portions of the LDPE inner thermoplastic sealing layer and aluminum foil layer are not adhered. Therefore, an EAA tie layer must be applied at greater thicknesses than an LDPE tie layer. This, combined with the higher cost of EAA, means that the use of EAA does not necessarily reduce the cost of producing the layered film structure.

[0009] Thus, there is a need for reducing the EAA tie layer thicknesses while providing an intact tie layer that maintains the EAA’s superior adhesion performance between adjacent layers.

SUMMARY OF THE INVENTION

[0010] In a class of embodiments, a layered film structure may comprise, in order: a thermoplastic sealing layer; a tie layer comprising an ethylene acrylic acid copolymer (EAA) having an acrylic acid content of about 5.5 wt% to about 6.5 wt%, based upon the total weight of the copolymer; a melt index (ASTM D1238-16 at l90°C and 2.16 kg) of about 8.0 g/lO min to about 8.4 g/lO min; and an average long-chain branching factor (LCBf/lOOOTC) as measured by gel permeation chromatography with viscometry (GPC-viscometer) of about 1.0 to about 2.0; and a barrier layer.

[0011] Optionally, the layered composition may further comprise, in order: a thermoplastic tie layer adjacent the barrier layer; a core layer; and an outer thermoplastic layer. [0012] In another class of embodiments, a packaging laminate may comprise the layered film structure as described above optionally with the additionally described layers.

[0013] In yet another class of embodiments, a container for a liquid food is made, at least in part, of the layered film structure as described above optionally with the additionally described layers.

[0014] In another class of embodiments, a method of producing the layered film structure as described above may comprise: coextruding an EAA melt and a thermoplastic sealing polymer melt onto the barrier layer with the EAA melt between the barrier layer and the thermoplastic sealing polymer melt.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following figures are included to illustrate certain aspects of the embodiments, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure.

[0016] FIG. 1 is an illustration of a layered film structure comprising, in order, a thermoplastic sealing layer, an EAA tie layer, and a barrier layer.

[0017] FIG. 2 is an illustration of a layered film structure comprising, in order, a thermoplastic sealing layer, an EAA tie layer, a barrier layer, a thermoplastic tie layer, a core layer, and an outer thermoplastic layer.

[0018] FIG. 3 is a plot of the total polyethylene and EAA coating weight measured at points about equidistant across the produced films (perpendicular the machine direction) for the total target coating weights was 25 grams per square meter (gsm).

[0019] FIG. 4 is a plot of the total polyethylene and EAA coating weight measured at points about equidistant across the produced films (perpendicular the machine direction) for the total target coating weights was 27 gsm.

[0020] FIG. 5 is a plot of the adhesion (N/15 cm) between the aluminum foil and the EAA layer measured at points about equidistant across the produced films (perpendicular the machine direction) for the 25 gsm coatings.

[0021] FIG. 6 is a plot of the adhesion (N/15 cm) between the aluminum foil and the EAA layer measured at points about equidistant across the produced films (perpendicular the machine direction) for the 27 gsm coatings.

DETAILED DESCRIPTION

[0022] Before the present compounds, components, compositions, and/or methods are disclosed and described, it is to be understood that unless otherwise indicated this invention is not limited to specific compounds, components, compositions, reactants, reaction conditions, ligands, metallocene structures, catalyst structures, or the like, as such may vary, unless otherwise specified.

[0023] In several classes of embodiments of the invention, the present disclosure is directed to a layered film structure that comprise a thermoplastic sealing layer, an EAA tie layer, and a barrier layer, where the EAA tie layer preferably comprises an EAA having an acrylic acid content of about 5.5 wt% to about 6.5 wt%, a melt index of about 8.0 g/lO min to about 8.4 g/lO min (ASTM D1238-16 at l90°C and 2.16 kg), and an average long-chain branching factor (LCBf/lOOOTC) as measured by gel permeation chromatography with viscometry (GPC- viscometer) of about 1.0 to about 2.0. Optionally, other layers can be included. In another class of embodiments, the present disclosure is directed to a method of coextruding the thermoplastic sealing layer and the EAA tie layer onto the barrier layer. Such layered compositions are useful in producing a packaging laminate, and more specifically, an aseptic food packaging.

Definitions

[0024] As used herein, the term“copolymer” is meant to include polymers having two or more monomers. The term“polymer” as used herein includes, but is not limited to, homopolymers, copolymers, terpolymers, etc., and alloys and blends thereof. The term “terpolymer” as used herein refers to a polymer synthesized from three different monomers. Terpolymers, in some embodiments, may be produced (1) by mixing all three monomers at the same time or (2) by sequential introduction of the different comonomers. The mixing of comonomers may be done in one, two, or possible three different reactors in series and/or in parallel. The term“polymer” as used herein also includes impact, block, graft, random, and alternating copolymers. The term“polymer” shall further include all possible geometrical configurations unless otherwise specifically stated. Such configurations may include isotactic, syndiotactic, and random (/._<?., atactic) symmetries.

[0025] The term“blend” or“polymer blend” as used herein refers to a mixture of two or more polymers. Blends may be produced by, for example, solution blending, melt mixing, or compounding in a shear mixer. Solution blending is common for making adhesive formulations comprising baled butyl rubber, tackifier, and oil. Then, the solution blend is coated on a fabric substrate, and the solvent evaporated to leave the adhesive.

[0026] The term“monomer” or“comonomer,” as used herein, can refer to the monomer used to form the polymer, /._<?., the unreacted chemical compound in the form prior to polymerization, and can also refer to the monomer after it has been incorporated into the polymer, also referred to herein as a“[monomer] -derived unit”. Different monomers are discussed herein, including propylene monomers, ethylene monomers, and diene monomers.

[0027] As used herein, the term“linear” relative to a polymer means a polymer having no detectable branching (quantitatively or qualitatively), preferably a long-chain branching factor of 1.0 (+/-0.02).

[0028] As used herein, the average long-chain branching factor (LCBf/lOOOTC) or (long chain branching factor per 1,000 total carbons) refers to the average number of branches per chain of polymer and, unless otherwise specified, is measured by GPC-viscometer.

[0029] As used herein, polydispersity index (PDI) refers to the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (i.e., Mw/Mn) where Mw and Mn are determined using GPC-viscometer.

[0030] As used herein, drawdown is measured as the average laminator speed (m/min) at which melt failure or melt break occurs at a constant line speed acceleration of 10 m/min each second, a fixed screw speed of 35 rpm (which is a fixed output of about 40kg/h), 280°C, and 35 rpm.

[0031] As used herein, melt index is measured by ASTM D1238-16 at l90°C and 2.16 kg.

[0032] As used herein, density is measured by ASTM 1505-10.

[0033] As used herein, the term“coextrusion” refers to an extrusion process where at least two molten polymer compositions are extruded and bonded together in a molten condition in the die exit.

[0034] As used herein, the term“extrusion lamination” refers to an extrusion process where at least one molten polymer composition is extruded between two substrates (e.g., films or film layers) to bond the two substrates together.

Layered Film Structures

[0035] FIG. 1 is an illustration of a layered film structure 100 comprising, in order, a thermoplastic sealing layer 102, an EAA tie layer 104, and a barrier layer 106. In other words, the EAA tie layer 104 is sandwiched between the thermoplastic sealing layer 102 and the barrier layer 106. More specifically, the thermoplastic sealing layer 102 has a first face 108 opposing a second face 110, the EAA tie layer 104 has a first face 112 opposing a second face 114, and the barrier layer 106 has a first face 116 opposing a second face 118. In the illustrated layered film structure 100, the first face 108 of the thermoplastic sealing layer 102 is exposed and not adjacent another layer, the second face 110 thermoplastic sealing layer 102 is adjacent the first face 112 of the EAA tie layer 104, the second face 114 of the EAA tie layer 104 is adjacent the first face 116 of the barrier layer 106, and the second face 118 of barrier layer 106 is exposed and not adjacent another layer.

[0036] The EAA tie layer comprises an EAA having an acrylic acid content of about 5.5 wt% to about 6.5 wt %, preferably about 5.7 wt% to about 6.2 wt%, or more preferably about 6.0 wt%.

[0037] The EAA tie layer comprises an EAA having a melt index (ASTM D1238-16 at l90°C and 2.16 kg) of about 8.0 g/lO min to about 8.4 g/lO min, preferably about 8.1 g/lO min to about 8.3 g/lO min, or more preferably about 8.2 g/lO min.

[0038] The EAA tie layer comprises an EAA having an average long-chain branching factor of about 1.0 to about 2.0, preferably about 1.3 to about 1.9, or more preferably about 1.5 to about 1.7.

[0039] The EAA tie layer comprises an EAA having a drawdown of about 180 m/min to about 200 m/min, preferably about 190 m/min to about 210 m/min, or more preferably about 195 m/min to about 205 m/min.

[0040] In any embodiment, the EAA of the EAA tie layer can have a PDI of about 16 to about 20, or preferably about 17 to about 18.

[0041] In any embodiment, the EAA of the EAA tie layer can have a Mw of about 100,000 g/mol to about 125,000 g/mol, or preferably about 110,000 g/mol to about 120,000 g/mol.

[0042] In any embodiment, the EAA of the EAA tie layer can have a density (ASTM 1505- 10) of about 0.925 g/cm³ to about 0.940 g/cm³, or preferably about 0.930 g/cm³ to about 0.935 g/cm³.

[0043] In any embodiment, the EAA of the EAA tie layer can have a melting temperature of about l00°C to about l05°C.

[0044] The EAA of the EAA tie layer can have the foregoing acrylic acid content; melt index, and average long-chain branching factor in combination with one or more of the foregoing PDI, Mw, drawdown, or density.

[0045] An example of a commercially available EAA suitable for use in the EAA tie layer is ESCOR™ 6000 (ethylene acrylic acid copolymer, available from ExxonMobil Chemical Company).

[0046] The EAA tie layer can have a thickness of about 3 microns to about 10 microns, preferably about 3 microns to about 7 microns, and more preferably about 3 microns to about 5 microns.

[0047] Examples of thermoplastic polymers suitable for use in the thermoplastic sealing layer include, but are not limited to, low density polyethylenes (LDPE), linear LDPE (LLDPE) (e.g., metallocene LLDPE), polyethylene-a-olefin copolymers, polypropylene, and blends thereof.

[0048] For a polyethylene-a-olefin copolymer, the preferred a-olefin comonomer content is below about 30 weight percent (wt%), preferably below about 20 wt%, and more preferably from about 1 wt% to about 15 wt%. Preferred a-olefin comonomers include, but are not limited to, propylene, l-butene, l-pentene, l-hexene, 3-methyl- l-pentene, 4-methyl- l-pentene, 1- octene, l-decene, and l-dodecene.

[0049] Examples of commercially available thermoplastic polymers include, but are not limited to, AFFINITY™ GA (a polyolefin elastomer, available from Dow Chemical Co.), AFFINITY™ GP (a polyolefin elastomer, available from Dow Chemical Co.), ENGAGE™ (a polyolefin elastomer, available from Dow Chemical Co.), DOWLEX™ (a polyethylene resin, available from Dow Chemical Co.), DOW™ LDPE (low density polyethylene, available from Dow Chemical Co.) (e.g., DOW™ LDPE 722), ELITE™ (a high a-olefin polyethylene resin, available from Dow Chemical Co.) (e.g., ELITE™ 5815, a metallocene LLDPE), EVOLUE™ (metallocene LLDPE, available from Mitsui Chemicals, Inc.), EXCEED™ (a polyethylene or polyethylene copolymer resin, available from ExxonMobil Chemical Company) (e.g., EXCEED™ 0019XC, ethylene l-hexene copolymers), EXCEED™ XP (a polyethylene or polyethylene copolymer resin, available from ExxonMobil Chemical Company), ENABLE™ (a polyethylene or polyethylene copolymer resin, available from ExxonMobil Chemical Company), and blends thereof.

[0050] The thermoplastic sealing layer can have a thickness of about 3 microns to about 50 microns, preferably about 10 microns to about 40 microns, and more preferably about 15 microns to about 30 microns.

[0051] The barrier layer is comprised of practically any suitable barrier material that is adapted to substantially prevent the transmission of oxygen or oxygen and water. Examples of barrier layers include, but are not limited to, aluminum foil, a metal/inorganic oxide thin film, polyethylene terephthalate, glycol-modified polyethylene terephthalate, acid-modified polyethylene terephthalate, ethylene vinyl alcohol copolymer (EVOH), nylon, polymers of meta-xylylenediamine (MXD6), polyvinylidene chloride (PVDC), polyethylene naphthalate (PEN), or polymer blends thereof. A preferred barrier layer for paper-based, single-use, disposable packaging containers is aluminum foil.

[0052] The metal/inorganic oxide thin film can be a vapor deposited film of inorganic oxide

(e.g., about 10 nm to about 500 nm thick) on a resin film (including the foregoing resins) (10 microns to about 30 microns thick). Example inorganic oxides include, but are not limited to, silicon oxide, tin oxide, zinc oxide, indium oxide, titanium oxide, aluminum oxide, and combinations thereof. Vapor deposition may be by any known method including, but not limited to, vacuum deposition, sputtering, chemical vacuum deposition, and plasma-chemistry vapor deposit (PCVD).

[0053] Optionally, one or both faces of the barrier layer can be treated to enhance adhesion to the adjacent layers. Example treatments include, but are not limited to, corona treatment, plasma treatment, ozonation treatment, and combinations thereof.

[0054] The barrier layer 102 can have a thickness of about 5 microns to about 50 microns, preferably about 5 microns to about 25 microns, and more preferably about 5 microns to about 15 microns.

[0055] FIG. 2 is an illustration of a layered film structure 200 comprising, in order, a thermoplastic sealing layer 202, an EAA tie layer 204, a barrier layer 206, a thermoplastic tie layer 220, a core layer 222, and an outer thermoplastic layer 224. More specifically, the thermoplastic sealing layer 202 has a first face 208 opposing a second face 210, the EAA tie layer 204 has a first face 212 opposing a second face 214, the barrier layer 206 has a first face 216 opposing a second face 218, the thermoplastic tie layer 220 has a first face 226 opposing a second face 228, the core layer 222 has a first face 230 opposing a second face 232, and the outer thermoplastic layer 224 has a first face 234 opposing a second face 236. In the illustrated layered film structure 200, the first face 208 of the thermoplastic sealing layer 202 is exposed and not adjacent another layer, the second face 210 thermoplastic sealing layer 202 is adjacent the first face 212 of the EAA tie layer 204, the second face 214 of the EAA tie layer 204 is adjacent the first face 216 of the barrier layer 206, the second face 218 of barrier layer 206 is adjacent the first face 226 of the thermoplastic tie layer 220, the second face 228 of thermoplastic tie layer 220 is adjacent the first face 230 of the core layer 222, the second face 232 of the core layer 222 is adjacent the first face 234 of the outer thermoplastic layer 224, and the second face 236 of the outer thermoplastic layer 224 is exposed and not adjacent another layer.

[0056] When the layered film structure 200 is used in paper-based, single-use, disposable packaging containers, the first face 208 of the thermoplastic sealing layer 202 is exposed to the liquid foods and the second face 236 of the outer thermoplastic layer 224 is exposed to the surroundings of the packaging container.

[0057] It should be noted that the second face 232 of the core layer 222, the first face 234 of the outer thermoplastic layer 224, and/or the second face 236 of the outer thermoplastic layer 224 may have ink or other dye/colorant thereon that is not considered an independent layer but rather a portion of the layer in which the ink or other dye/colorant has been applied. The ink is useful in creating labels for paper-based, single-use, disposable packaging containers.

[0058] Examples of thermoplastic polymers suitable for use in the thermoplastic tie layer include, but are not limited to, LDPE, linear LDPE (e.g., metallocene LLDPE), polyethylene- a-olefin copolymers, polypropylenes, ethylene vinyl acetate copolymers (EVA), ionomers, and blends thereof. Examples of commercially available thermoplastic polymers include, but are not limited to, the commercially available thermoplastic polymers described herein relative to the thermoplastic sealing layer.

[0059] The thermoplastic tie layer can have a thickness of about 3 microns to about 50 microns, preferably about 3 microns to about 25 microns, and more preferably about 3 microns to about 15 microns.

[0060] Examples of core layers include, but are not limited to, synthetic paper, cellulose fiber paper, and a polymer (e.g., a polyester). Preferably, the core layer comprises cellulose fiber paper. Optionally, one or more faces of the core layer may be treated. Examples of treatments include, but are not limited to, flame treatment, corona treatment, plasma treatment, and combinations thereof.

[0061] The core layer can have a thickness of about 100 microns to about 250 microns, preferably about 115 microns to about 225 microns, and more preferably about 125 microns to about 200 microns.

[0062] Preferably, the outer thermoplastic layer is also heat sealable. Examples of thermoplastic polymers suitable for use in the outer thermoplastic layer include, but are not limited to, LDPE, linear LDPE, medium density polyethylenes (MDPE), polyethylene- a-olefin copolymers, polypropylene, and blends thereof. Preferably, the outer thermoplastic layer comprises LDPE. Examples of commercially available thermoplastic polymers include, but are not limited to, the commercially available thermoplastic polymers described herein relative to the thermoplastic sealing layer.

[0063] The outer thermoplastic layer can have a thickness of about 3 microns to about 50 microns, preferably about 10 microns to about 40 microns, and more preferably about 15 microns to about 30 microns.

[0064] Referring again to FIG. 2, an example of a layered film structure comprises, in order, a thermoplastic sealing layer 202 (e.g., comprising polyethylene), an EAA tie layer 204 (e.g., having acrylic acid content, melt index, and average long-chain branching factor described herein, optionally in combination with one or more of the foregoing PDI, Mw, drawdown, or density), a barrier layer 206 (e.g., comprising aluminum foil), a thermoplastic tie layer 220 (e.g., comprising LDPE), a core layer 222 (e.g., comprising cellulose fiber paper), and an outer thermoplastic layer 224 (e.g., comprising LDPE).

[0065] Alternative layered film structures are also contemplated such that layered film structure includes an EAA tie layer sandwiched between a thermoplastic sealing layer and a barrier layer. For example, a layered film structure similar to FIG. 2 is contemplated with additional layers.

Making Layered Film Structures

[0066] Layered films (e.g., layered film 100 of FIG. 1) can be extruded by cast extrusion or blown film extrusion. The invention is concerned with blown film extrusion and especially coextrusion. A blown film coextrusion process can comprise: separately melting the EAA and thermoplastic sealing polymer, extruding the corresponding melts onto the barrier layer with the EAA extruded melt in contact with and separating the barrier layer and the thermoplastic sealing polymer extruded melt, and cooling the layers to produce the layered film structure.

[0067] Extrusion and coextrusion equipment and methods typically use grams per square meter (gsm) to describe a target thickness or final thickness of the film or film layer. The actual thickness in microns depends on the density of the composition in the film or film layer. For example, the EAA melt can be extruded with target thickness of about 2.7 gsm to about 9.5 gsm to achieve EAA tie layer thickness of about 3 microns to about 10 microns, or preferably about 2.7 gsm to about 6.6 gsm to achieve EAA tie layer thickness of about 3 microns to about 7 microns. In another example where the thermoplastic sealing polymer is a LDPE with a density of about 0.91 g/cm³ to about 0.94 g/cm³, the thermoplastic sealing polymer melt can be extruded with target thickness of about 2.7 gsm to about 47 gsm to achieve thermoplastic sealing polymer layer thickness of about 3 microns to about 50 microns, or preferably about 4.5 gsm to about 14.1 gsm to achieve thermoplastic sealing polymer layer thickness of about 5 microns to about 15 microns.

[0068] Variables that can affect the resultant layer thickness include, but not limited to, the die gap, melt temperature, the line speed, the melt pressure, and the screw speed (which relates to how fast the polymer is extruded from the die). Further, there can be variation in the degree each variable effects the resultant layer thickness between different pieces of equipment.

[0069] The melt temperature for either the EAA melt or the thermoplastic sealing polymer melt can be about 250°C to about 300°C, preferably about 260°C to about 290°C, or more preferably about 270°C to about 285°C. [0070] The melt pressure is the melt pressure at the die and can for either the EAA melt or the thermoplastic sealing polymer melt can be about 150 bar to about 250 bar, or preferably about 160 bar to about 200 bar.

[0071] Typical coextrusion line speeds for industrial manufacturing of layered film structures can be about 450 m/min or greater. The line speed for producing the layered film structures described herein can be slower if desired (e.g., down to about 200 m/min), preferably about 300 to about 600 m/min, preferably about 400 m/min to about 550 m/min, or more preferably about 450 m/min to about 500 m/min. As illustrated in the examples below, the EAA compositions of the EAA tie layer described herein advantageously can produce thinner films at industrial manufacturing speeds where other EAA compositions fail to produce a continuous film.

[0072] Layered films (e.g., layered film 200 of FIG. 2) can be manufactured by extrusion lamination to adhere two layered structures together with a thermoplastic tie layer. For example, the first layered structure can be a thermoplastic sealing layer/EAA tie layer/barrier layer structure, and the second layered structure can be a core layer/outer thermoplastic layer structure where the thermoplastic tie layer adheres the barrier layer to the core layer to produce a layered film like that illustrated in FIG. 2. Such layered films and similar layered films can then be shaped, filled with liquid foods, and sealed to produce paper-based, single-use, disposable packaging containers.

[0073] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term“about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the embodiments of the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0074] One or more illustrative embodiments incorporating the invention embodiments disclosed herein are presented herein. Not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment incorporating the embodiments of the present invention, numerous implementation-specific decisions must be made to achieve the developer's goals, such as compliance with system-related, business-related, government- related and other constraints, which vary by implementation and from time to time. While a developer's efforts might be time-consuming, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in the art and having benefit of this disclosure.

[0075] While compositions and methods are described herein in terms of“comprising” various components or steps, the compositions and methods, can also“consist essentially of’ or“consist of’ the various components and steps.

[0076] To facilitate a better understanding of the embodiments of the present invention, the following examples of preferred or representative embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the invention.

EXAMPLES

havered Film Preparation

[0077] Polyethylene (a blend of 70 wt% ELITE™ 5815 and 30 wt% DOW™ LDPE 722) was coextruded with two ESCOR™ grades of EAA (ESCOR™ 5020 and ESCOR™ 6000, see properties in Table 1) onto aluminum foil at a line speed of 450 m/min on a laminating extruder that is commercially available from Egan Davis Standard. The polyethylene extrusion conditions were kept constant and set for a 20 gsm coating

[0078] The EAA extrusion parameters were varied per Table 2 and correspond to a 5 gsm coating weight or a 7 gsm coating weight. Therefore, the total target coating weights were 25 gsm and 27 gsm. The torque (or energy required to mix the polymer) is similar for both ESCOR™ grades that extruded to a proper film/layer. Therefore, the processability of both is similar, so the resultant extruded film/layer comparison relate to how each polymer extrudes with minimal effects from processing.

Table 1. Properties of ESCOR™ Grades

Table 2. Production Parameters for Test Layered Films

[0079] FIG. 3 and FIG. 4 are plots of the total polyethylene and EAA coating weight measured at points about equidistant across the produced films (perpendicular the machine direction) for the total target coating weights were 25 gsm and 27 gsm, respectively. The film widths can vary and edge effects are known, so analysis is based on the central sections 3-8 of the film.

[0080] For the target coating weight of 25 gsm (FIG. 3), the ESCOR™ 5020 tie layer was about 30 gsm across the film while the ESCOR™ 6000 was about 25 gsm to about 27 gsm. Therefore, the ESCOR™ 6000 tie layer (which is within the EAA composition tie layer of the present invention) more closely achieved the desired thickness.

[0081] For the target coating weight of 27 gsm (FIG. 4), the ESCOR™ 5020 tie layer was about 27 gsm to about 30 gsm across the film while the ESCOR™ 6000 was less than about 25 gsm. Therefore, the ESCOR™ 6000 tie layer had a lower thickness by at least 2 gsm (or about 7% relative to the target). Further, the ESCOR™ 6000 tie layer was about 17% thinner than the ESCOR™ 5020 tie layer.

[0082] FIGS. 5 and 6 are plots of the adhesion (N/15 cm) between the aluminum foil and the EAA layers measured at points about equidistant across the produced films (perpendicular the machine direction) for the 25 gsm and 27 gsm coatings, respectively. The industry- accepted adhesion requirement is 300 N/15 cm. The film widths can vary and edge effects are known, so analysis is based on the central sections 3-8 of the film.

[0083] For the target coating weight of 25 gsm (FIG. 5), the two EAA materials performed comparable at about 350 N/15 cm to about 375 N/15 cm.

[0084] For the target coating weight of 27 gsm (FIG. 6) where the ESCOR™ 6000 had a significantly thinner layer, the ESCOR™ 6000 had lower adhesion at about 325 N/15 cm to about 360 N/15 cm while the ESCOR™ 5020 tie layer adhered to the aluminum foil at about 375 N/15 cm to about 400 N/15 cm. However, the thinner, and consequently less expensive, ESCOR™ 6000 tie layer is well within the industry-accepted adhesion requirements.

[0085] This example illustrates that at least a 17% decrease in EAA raw material costs with acceptable adhesion can be achieved when producing layered film structures like paper-based, single-use, disposable packaging containers.

[0086] Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present invention. The invention illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of“comprising,”“containing,” or“including” various components or steps, the compositions and methods can also“consist essentially of’ or“consist of’ the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form,“from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles“a” or“an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces.

Claims

CLAIMS What is claimed is:

1. A layered film structure comprising, in order:

a thermoplastic sealing layer;

an tie layer comprising an ethylene acrylic acid copolymer (EAA) having an acrylic acid content of about 5.5 wt% to about 6.5 wt%, based upon the total weight of the copolymer, a melt index (ASTM D1238-16 at l90°C and 2.16 kg) of about 8.0 g/lO min to about 8.4 g/lO min, an average long-chain branching factor (LCBf/lOOOTC) as measured by gel permeation chromatography with viscometry (GPC- viscometer) of about 1.0 to about 2.0, and a drawdown of about 180 m/min to about 210 m/min; and

a barrier layer.

2. The layered film structure of claim 1, wherein the EAA has the acrylic acid content of about 5.7 wt% to about 6.2 wt%, based upon the total weight of the copolymer, the melt index of about 8.1 g/ 10 min to about 8.3 g/ 10 min, the average long-chain branching factor of about 1.5 to about 1.7, and the drawdown of about 190 m/min to about 210 m/min.

3. The layered film structure of any one of the preceding claims, wherein the EAA has the acrylic acid content of about 6.0 wt%, based upon the total weight of the copolymer, the melt index of about 8.2 g/lO min, the average long-chain branching factor of about 1.5 to about 1.7, and the drawdown of about 195 m/min to about 205 m/min.

4. The layered film structure of any one of the preceding claims, wherein the EAA has a density of about 0.925 g/cm³ to about 0.940 g/cm³.

5. The layered film structure of any one of the preceding claims, wherein the EAA has a melting temperature of about l00°C to about 105 °C.

6. The layered film structure of any one of the preceding claims, wherein the EAA has a polydispersity index as measure by GPC-viscometer of about 16 to about 20.

7. The layered film structure of any one of the preceding claims, wherein the EAA has a weight average molecular weight (M_w) as measure by GPC-viscometer of about 100,000 to about 125,000 g/mol.

8. The layered film structure of any one of the preceding claims, wherein the EAA tie layer has a thickness of about 3 microns to about 10 microns.

9. The layered film structure of any one of the preceding claims, wherein the EAA tie layer has a thickness of about 3 microns to about 7 microns.

10. The layered film structure of any one of the preceding claims, wherein the thermoplastic sealing layer comprises at least one selected from the group consisting of a low density polyethylene (LDPE), a linear LDPE, a polyethylene-a-olefin copolymer, a polypropylene, and blends thereof.

11. The layered film structure of any one of the preceding claims, wherein the thermoplastic sealing layer has a thickness of about 3 microns to about 50 microns.

12. The layered film structure of any one of the preceding claims, wherein the thermoplastic sealing layer has a thickness of about 5 microns to about 15 microns.

13. The layered film structure of any one of the preceding claims, wherein the barrier layer comprises at least one selected from the group consisting of aluminum foil, a metal/inorganic oxide thin film, polyethylene terephthalate, glycol-modified polyethylene terephthalate, acid- modified polyethylene terephthalate, ethylene vinyl alcohol copolymer (EVOH), nylon, polymers of meta-xylylenediamine (MXD6), polyvinylidene chloride (PVDC), polyethylene naphthalate (PEN), or blends thereof.

14. The layered film structure of any one of the preceding claims, wherein the barrier layer has a thickness of about 5 microns to about 50 microns.

15. The layered film structure of any one of the preceding claims further comprising, in order:

a thermoplastic tie layer adjacent the barrier layer; a core layer; and

an outer thermoplastic layer.

16. The layered film structure of claim 15, wherein the core layer and/or the outer thermoplastic layer comprises ink, dye, and/or colorant.

17. The layered film structure of claim 15 or 16, wherein the thermoplastic tie layer comprises at least one selected from the group consisting of a LDPE, a linear LDPE, a polyethylene- a-olefin copolymer, a polypropylene, an ethylene vinyl acetate copolymer (EVA), an ionomer, and blends thereof.

18. The layered film structure of one of claims 15-17, wherein the core layer comprises at least one selected from the group consisting of synthetic paper, cellulose fiber paper, and a polyester.

19. The layered film structure of one of claims 15-18, wherein the outer thermoplastic layer comprises at least one selected from the group consisting of a LDPE, a linear LDPE, a medium density polyethylene (MDPE), a polyethylene- a-olefin copolymer, a polypropylene, and blends thereof.

20. The layered film structure of one of claims 15-19, wherein the thermoplastic sealing layer comprises polyethylene, the barrier layer comprises aluminum foil, the thermoplastic tie layer comprises LDPE, the core layer comprises cellulose fiber paper, and the outer thermoplastic layer comprise LDPE.

21. A packaging laminate comprising the layered film structure of any one of the preceding claims.

22. A container for a liquid food made, at least in part, of the layered film structure of one of claims 1-20.

23. A method of producing the layered film structure of one of claims 1-14, the method comprising: coextruding an EAA melt and a thermoplastic sealing polymer melt onto the barrier layer with the EAA melt between the barrier layer and the thermoplastic sealing polymer melt.

24. The method of claim 23, wherein coextruding is at a line speed of about 450 meters per minute (mpm) or greater.