WO2019018023A1

WO2019018023A1 - Laminate material and process of making the same

Info

Publication number: WO2019018023A1
Application number: PCT/US2018/027055
Authority: WO
Inventors: Linda M. Van Den Bossche; Nilesh C. SHAH; Joe J. THOPPIL; Kiran C. VIBHANDIK; Devika Singh
Original assignee: Exxonmobil Chemical Patents Inc.
Priority date: 2017-07-21
Filing date: 2018-04-11
Publication date: 2019-01-24

Abstract

The present invention provides a laminate material including a substrate layer, a tie layer, and a sealing layer. The tie layer and the sealing layer are co-extrusion coated onto the substrate layer. The tie layer includes a first polyethylene polymer that can contain a low density polyethylene. The sealing layer includes a second polyethylene polymer that can contain a linear low density polyethylene having a melt index of from about 15 to about 35 g/cm3.

Description

Title: LAMINATE MATERIAL AND PROCESS OF MAKING THE SAME Inventors: Linda M. Van den Bossche; Nilesh C. Shah; Joe J. Thoppil; Kiran C. Vibhandik; Devika Singh PRIORITY CLAIM

[0001] This application claims the benefit of Serial No. 62/535,475, filed July 21, 2017 and is incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to laminate material, in particular, to lamination film structures, that comprises a co-extrusion coated tie layer and sealing layer comprising a low density polyethylene (LDPE) and a linear low density polyethylene (LLDPE).

BACKGROUND OF THE INVENTION

[0003] Polyethylene or polypropylene polymers are often used in making blown or cast films. Such films can be further used in formation of lamination structures as a sealant layer. In preparation of lamination film structures, pre-made polyethylene and polypropylene films can be bonded with a substrate layer comprising, for example, polyethylene terephthalate (PET), aluminum foil, and biaxially oriented polypropylene (BOPP), by way of an adhesive lamination process or extrusion lamination process. The polyethylene can comprise low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), metallocene polyethylene (mPE), ethylene vinyl acetate (EVA), and ethylene acrylic acid (EAA) polymers depending on various desired applications.

[0004] Typical laminate film structures made from an adhesive lamination process comprise a substrate layer, such as PET layer, a blown or cast film comprising LDPE and/or LLDPE and/or mPE, and an adhesive layer bonding the substrate layer and the film layer.

[0005] However, an extrusion or adhesive lamination process requires pre-making of blown or cast films, which involves the production cost for making film with managing raw material inventory, logistics and time required, and the conventional adhesive lamination process may require a certain film thickness, for example, greater than 25 μιη. Also, the adhesive lamination process usually requires the use of a solvent-based or water-based solvent, which also involves processing cost and time required to cure.

[0006] Alternative processes for making lamination structures comprise an extrusion coating process. In the extrusion coating process, polymers are melted under heat and pressure in an extruder and the molten polymers are extruded through a slit die as a thin web. This web, at high temperature, is drawn down and coated onto a moving substrate. [0007] U.S. Patent Application No. 2010/0221528A1 describes an extrusion coated article and process to extrusion coat a substrate. A blend of LDPE having MI2 greater than 5 dg/min and m-LLDPE having a MI2 less than 5 dg/min and by differential scanning Calorimetry, at least two melting points is used.

[0008] U.S. Patent No. 8,889,794 discloses a composition of matter suitable for use in extrusion coating applications. The composition comprises a blend of particular LLDPE with particular LDPE. The LLDPE has the following properties: a density in the range of from 0.89 g/cc to 0.97 g/cc, an MWD less than 2.8, a melt index (I₂) in the range of 4.0 to 25 g/10 min, a Comonomer Distribution Constant in the range of from greater than from 45 to 400, and a vinyl unsaturation of less than 0.12 vinyls per one thousand carbon atoms present in the backbone of the ethylene-based polymer composition. The LDPE has a melt index (I₂) in the range of 0.1 to 15 g/10 min and has a particular melt strength.

[0009] WO 99/09097 discloses an improved extrusion coating comprising at least two polyethylene homopolymers, one component being a low melt index medium density polyethylene homopolymer, and another component being a high melt index low density polyethylene homopolymer. Superior heat seal strength is said to have achieved with such blend.

[0010] WO 99/09097 discloses an extrusion coated substrate having a coating comprising a polyethylene produced by polymerization catalyzed by a single site catalyst and comprising as comonomers to ethylene at least two C4-12 alpha olefins.

[0011] Other Polymer compositions that are said to be suitable for extrusion coating can be found in WO 2012/170526, WO 2013/178242, WO 2013/006409, WO 95/01250, and EP 2077296.

[0012] However, there is still a need for a process for extrusion coating a substrate to replace the adhesion limitation and to achieve improved properties or a balance thereof, such as high seal strength, low sealing imitation temperature, low neck-in, low thickness, high draw down, broad hot-tack plateau, low dynamic coefficient of friction, cost saving, and other properties.

SUMMARY OF THE INVENTION

[0013] In various embodiments, the invention relates to a laminate material comprising a substrate layer, and a tie layer and a sealing layer, both are co-extrusion coated onto the substrate, the tie layer comprises a first polyethylene polymer having a density of 0.911 to 0.935 g/cm³, a branching index g'_Vi_S of 0.05 to 0.85, and a melt index of from 0.01 to 15 g/10 min; and the sealing layer comprises a second polyethylene polymer and optionally the first polyethylene polymer, the second polyethylene polymer being a copolymer derived from ethylene and one or more C3 to C20 a-olefin comonomers and having a density of 0.905 to 0.926 g/cm³, a melt index of 15.0 to 35.0 g/10 min, a branch index g'_Vi_S of greater than 0.85, a compositional distribution breadth index of 60% to 85%, and a molecular weight distribution of 1.5 to 4.0.

[0014] In some embodiments when the sealing layer comprises the first polyethylene polymer, the sealing layer comprises from 5 to 70 wt%, preferably from 5 to 30 wt% of the first polyethylene polymer and from 30 to 95 wt%, preferably from 70 to 95 wt% of the second polyethylene polymer.

[0015] In various embodiments, the invention relates to a process for co-extrusion coating the tie layer and the sealing layer onto a substrate to form a laminate material.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0016] Various specific embodiments, versions and examples of the invention will now be described, including preferred embodiments and definitions that are adopted herein for purposes of understanding the claimed invention. While the following detailed description gives specific embodiments, those skilled in the art will appreciate that these embodiments are exemplary only, and that the invention can be practiced in other ways.

[0017] For purposes of determining infringement, the scope of the invention will refer to any one or more of the appended claims, including their equivalents, and elements or limitations that are equivalent to those that are recited. Any reference to the "invention" may refer to one or more, but not necessarily all, of the inventions defined by the claims.

[0018] It must also be noted that, as used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless otherwise specified.

[0019] That said, described herein are improved laminate materials comprising a substrate layer, and a tie layer and a sealing layer, which are co-extrusion coated onto the substrate layer. The present laminate materials have one or more advantages and properties of (a) a broad hot tack plateau, (b) a low seal initiation temperature, (c) a high seal strength, and (d) a low dynamic coefficient of friction, and (e) cost saving compared to other technologies, such as adhesive coating.

Definitions

[0020] For the purposes of this disclosure, the following definitions will apply, unless otherwise stated: molecular weight distribution ("MWD") is equivalent to the expression M_w/M_n. The expression M_w/M_n is the ratio of the weight average molecular weight (M_w) to the number average molecular weight (M_n). The weight average molecular weight is given by:

∑n,M,

the number average molecular weight is given by:

the z- average molecular weight is given by:

M ,

∑n,M, ² ,

i

where m in the foregoing equations is the number fraction of molecules of molecular weight Mi. Measurements of M_w, M_z, and M_n are determined by Gel Permeation Chromatography. The measurements proceed as follows. Gel Permeation Chromatography (Agilent PL- 220), equipped with three in-line detectors, a differential refractive index detector (DRI), a light scattering (LS) detector, and a viscometer is used. Experimental details, including detector calibration, are described in: T. Sun, P. Brant, R. R. Chance, and W. W. Graessley, Macromolecules, Volume 34, Number 19, pp. 6812-6820, (2001). Three Agilent PLgel ΙΟμιη Mixed-B LS columns are used. The nominal flow rate is 0.5 niL/min, and the nominal injection volume is 300 μί. The various transfer lines, columns, viscometer and differential refractometer (the DRI detector) are contained in an oven maintained at 145°C. Solvent for the experiment is prepared by dissolving 6 grams of butylated hydroxytoluene as an antioxidant in 4 liters of Aldrich reagent grade 1 ,2,4-trichlorobenzene (TCB). The TCB mixture is then filtered through a 0.1 μιη Teflon filter. The TCB is then degassed with an online degasser before entering the GPC-3D. Polymer solutions are prepared by placing dry polymer in a glass container, adding the desired amount of TCB, then heating the mixture at 160°C with continuous shaking for about 2 hours. All quantities are measured gravimetrically. The TCB densities used to express the polymer concentration in mass/volume units are 1.463 g/ml at about 21 °C and 1.284 g/ml at 145°C. The injection concentration is from 0.5 to 2.0 mg/ml, with lower concentrations being used for higher molecular weight samples. Prior to running each sample, the DRI detector and the viscometer are purged. The flow rate in the apparatus is then increased to 0.5 ml/minute, and the DRI is allowed to stabilize for 8 hours before injecting the first sample. The LS laser is turned on at least 1 to 1.5 hours before running the samples. The concentration, c, at each point in the chromatogram is calculated from the baseline-subtracted DRI signal, ¾ I, using the following equation:

c = ^KDRl^lDRl l(^dn/dc)'

where K_DRI is a constant determined by calibrating the DRI, and (dn dc) is the refractive index increment for the system. The refractive index, n = 1.500 for TCB at 145 °C and λ = 690 nm. Units on parameters throughout this description of the GPC-3D method are such that concentration is expressed in g/cm³, molecular weight is expressed in g/mole, and intrinsic viscosity is expressed in dL/g.

[0021] The LS detector is a Wyatt Technology High Temperature DAWN HELEOS. The molecular weight, M, at each point in the chromatogram is determined by analyzing the LS output using the Zimm model for static light scattering (M.B. Huglin, LIGHT SCATTERING FROM POLYMER SOLUTIONS, Academic Press, 1971):

i _ _{+ 2A c}

AR(e) ΜΡ(Θ) ²

here, AR(9) is the measured excess Rayleigh scattering intensity at scattering angle Θ, c is the polymer concentration determined from the DRI analysis, A₂ is the second virial coefficient.

Ρ(θ) is the form factor for a monodisperse random coil, and K₀ is the optical constant for the system:

where is Avogadro's number, and (dn dc) is the refractive index increment for the system, which take the same value as the one obtained from DRI method. The refractive index, n = 1.500 for TCB at 145°C and λ = 657 nm.

[0022] A high temperature Viscotek Corporation viscometer, which has four capillaries arranged in a Wheatstone bridge configuration with two pressure transducers, is used to determine specific viscosity. One transducer measures the total pressure drop across the detector, and the other, positioned between the two sides of the bridge, measures a differential pressure. The specific viscosity, η₈, for the solution flowing through the viscometer is calculated from their outputs. The intrinsic viscosity, [η], at each point in the chromatogram is calculated from the following equation:

η₈ = ο[η] + 0.3(ο[η])2.

where c is concentration and was determined from the DRI output.

[0023] The branching index (g'_vi_s) is calculated using the output of the GPC-DRI-LS-VIS method as follows. The average intrinsic viscosity, [T|]_avg, of the sample is calculated by:

∑c, hl

[η] avg

∑<=,

where the summations are over the chromatographic slices, i, between the integration limits.

[0024] The branching index g'_vjs is defined as:

M_v is the viscosity-average molecular weight based on molecular weights determined by LS analysis. Z average branching index (g'zave) is calculated using Ci = polymer concentration in the slice i in the polymer peak times the mass of the slice squared, Mi². All molecular weights are weight average unless otherwise noted. All molecular weights are reported in g/mol unless otherwise noted. This method is the preferred method of measurement and used in the examples and throughout the disclosures unless otherwise specified. See also, for background, Macromolecules, Vol. 34, No. 19, Effect of Short Chain Branching on the Coil Dimensions of Polyolefins in Dilute Solution, Sun et al , pg. 6812-6820 (2001).

[0025] A "polymer" has two or more of the same or different mer units. A "homopolymer" is a polymer having mer units that are the same. A "copolymer" is a polymer having two or more mer units that are different from each other. A "terpolymer" is a polymer having three mer units that are different from each other.

[0026] Likewise, the definition of polymer, as used herein, includes copolymers, and the like. Thus, as used herein, the terms "polyethylene," "polyethylene polymer," "ethylene copolymer," and "ethylene based polymer" means a polymer or copolymer comprising at least 50.0 mol% ethylene units (preferably at least 70.0 mol% ethylene units, more preferably at least 80.0 mol% ethylene units, even more preferably at least 90.0 mol% ethylene units, even more preferably at least 95.0 mol% ethylene units or 100.0 mol% ethylene units (in the case of a homopolymer)). Furthermore, the term "polyethylene composition" means a blend containing one or more polyethylene components. [0027] To facilitate discussion of different structures of laminate material of the invention, adjacent layers are separated by a slash (/). Using this notation, a three-layer laminate material would be denoted as substrate/tie layer/ sealing layer.

First Polyethylene polymer

[0028] The first polyethylene polymer can comprise a low density polyethylene and has one or more of the following properties (determined according to the techniques described above, unless stated otherwise):

(a) a density of about 0.910 to about 0.935 g/cm³, or about 0.910 to about 0.930 g/cm³, or about 0.910 to about 0.925 g/cm³;

(b) a g'_vis as described herein of about 0.05 to about 0.85, particularly about 0.05 to about 0.80, about 0.05 to about 0.75, about 0.05 to about 0.70, about 0.05 to about 0.65, about 00.5 to about 0.60, or about 0.05 to about 0.55;

(c) a Melt Index ("MI") of less than about 15 g/10 min, for example from 0.05 to 15 g/10 min, or from about 0.1 to about 12 g/10 min, or from about 0.1 to about 10 g/10 min;

(d) a melting point of about 90°C or more, as measured by industry acceptable thermal methods, such as Differential Scanning Calorimetry (DSC), for example, from about 90°C to about 130.0°C; from about 95.0°C to about 120.0°C; from about 95.0°C to about 110.0°C;

(d) a Molecular Weight ("M_w" measured by Malls+Ri) of about 630,000 to about 1,400,000 g/mol;

(e) a Number Average Molecular Weight ("M_n" measured by viscometry+Ri) of about 16,500 to about 24,500 g/mol;

(f) a G' (storage modulus at G" of 500 Pa at 170°C) of about 100 to about 140 Pa; and

(g) a Molecular Weight Distribution ("MWD" Mw (Malls)/Mn (universal)) of about 25 to about 70.

[0029] The first polyethylene polymer may be homopolymers or copolymers of ethylene and comonomers. In some embodiments, the first polyethylene polymer can be a copolymer of ethylene and one or more C3 to C20 comonomers. Typically, the copolymers include about 99.0 to about 80.0 wt%, about 99.0 to about 85.0 wt%, about 99.0 to about 87.5 wt%, about 95.0 to about 90.0 wt%, of polymer units derived from ethylene and about 1.0 to about 20.0 wt%, about 1.0 to about 15.0 wt%, about 1.0 to about 12.5 wt%, or about 5.0 to about 10.0 wt% of polymer units derived from one or more comonomers. In some embodiments, the comonomers can be polar and comprise vinyl acetate, methyl acetate, butyl acetate, acrylic acid, ionomer, and terpolymer.

[0030] In some embodiments, the first polyethylene polymer can include about 0.1 wt% to about 10.0 wt% units derived from one or more modifiers, based on the total weight of the first polyethylene polymer. The amount of the modifier(s) can range from a low of about 0.1 wt%, about 0.3 wt%, or about 0.8 wt% to a high of about 3.0 wt%, about 6.0 wt%, or about 10.0 wt%, based on the total weight of the first polyethylene polymer. Suitable modifiers, also called chain transfer agents, are described in Advances in Polymer Science, Vol. 7, pp. 386-448 (1970). Particular modifiers are C2 to C12 unsaturated modifiers containing at least one unsaturation, but they can also contain multiple conjugated or non-conjugated unsaturations. In case of multiple unsaturations, it is preferred that they are non-conjugated. In certain embodiments, the unsaturation of the C2 to C12 unsaturated modifier can be di- substituted with one or more alkyl groups in the beta position. Preferred C2 to C12 unsaturated modifiers include propylene, isobutylene, or a combination thereof.

[0031] The first polyethylene polymer can further contain one or more additives. Suitable additives can include, but are not limited to: stabilization agents such as antioxidants or other heat or light stabilizers; anti-static agents; crosslink agents or co-agents; crosslink promotors; release agents; adhesion promotors; plasticizers; or any other additive and derivatives known in the art. Suitable additives can further include one or more anti- agglomeration agents, such as oleamide, stearamide, erucamide, or other derivatives with the same activity as known to the person skilled in the art. Preferably, the HPPE resin contains less than about 0.15 wt% of such additives, based on the total weight of the first polyethylene polymer. When present, the amount of the additives can also range from a low of about 0.01 wt%, about 0.02 wt%, about 0.03 wt%, or about 0.05 wt% to a high of about 0.06 wt%, about 0.08 wt%, about 0.11 wt%, or about 0.15 wt%.

[0032] The first polyethylene polymer described herein is not limited by any particular method of preparation and may be formed using any process known in the art. For example, the LDPE may be formed by high pressure autoclave or tubular reactor processes.

[0033] The first polyethylene polymer that are useful in this invention can include those commercially available under the trade designation ExxonMobil™ LDPE from ExxonMobil Chemical Company in Houston, Texas, including but not limited to those available under the grade names: LD250, LD259, LD258, LD251, LD252, LD650 LD653, LD200.48, LD201.48 and LD202.48, and LDPE available from Reliance Industries in India under grade name of 1070LA17. Second Polyethylene polymer

[0034] The second polyethylene polymer comprises a linear low density polyethylene comprising a copolymer derived from ethylene and one or more C3 to C20 a-olefin comonomers. In various embodiments, the second polyethylene polymer has one or more of the following properties:

(a) a density (ASTM D4703/D1505) of about 0.905 to about 0.926 g/cm³, or about 0.915 to about 0.925 g/cm³, or about 0.915 to about 0.920 g/cm³, or about 0.916 to about 0.920 g/cm³;

(b) a Compositional Distribution Breadth Index ("CDBI") of about 60% to about 85%, or about 65% to about 85%. "CDBI" means the weight percent of the copolymer molecules having a comonomer content within 50% of the median total molar comonomer content. The CDBI of a copolymer may be determined using well known techniques for isolating individual fractions of a sample of the copolymer. One such technique is Temperature Rising Elution Fraction (TREF), as described in Wild, et al, J. Poly. Scl, Poly. Phys. Ed., vol. 20, p. 441 (1982), which is incorporated herein by reference for this purpose;

(c) a weight average molecular weight (Mw) of the second polyethylene polymer may be from about 15,000 to about 400,000 g/mol, from about 20,000 to about 250,000 g/mol, from about 20,000 to about 200,000 g/mol, from about 25,000 to about 150,000 g/mol, from about 150,000 to about 400,000 g/mol, from about 200,000 to about 400,000 g/mol, or from about 250,000 to about 350,000 g/mol;

(d) a Molecular Weight Distribution ("MWD," "Mw/Mn") of about 1.5 to about 4.0, or about 2.0 to about 3.5. Techniques for determining the molecular weight ("Mw" and "Mn") and molecular weight distribution ("MWD," "Mw/Mn") can be found in U. S. Patent No. 4,540,753 to Cozewith et al. and references cited therein, and in VerStrate et al, Macromolecules, vol. 21, pg. 3360 (1988) and references cited therein, which are incorporated herein by reference for this purpose;

(e) a Melt Index ("MI," ASTM D-1238, 2.16 kg, 190°C) of about 12 to about 35 g/10 min, about 15 to about 35 g/10 min, or about 15 to about 25 g/10 min, or about 17 to about 25 g/10 min, or about 18 to about 20 g/10 min; and

(f) a branching index (as defined herein) g'_Vi_S of greater than about 0.85, or greater than about 0.9, or greater than about 0.95, or greater than about 0.97, or greater than about 0.98, indicating a substantially linear structure of the molecular chain.

[0035] In a class of embodiments, the second polyethylene polymer may have one or more of the following properties: a melt index (MI) (190°C/2.16 kg) of from about 18 g/10 min to about 20 g/10 min; a M_w of from about 20,000 to about 200,000 g/mol; a M_w Mn of from about 2.0 to about 4.5; and a density of from about 0.918 to about 0.920 g/cm³.

[0036] The second polyethylene polymer comprises from about 70.0 wt% to about 100.0 wt% of units derived from ethylene. The lower limit on the range of ethylene content may be from about 70.0 wt%, about 75.0 wt%, about 80.0 wt%, about 85.0 wt%, about 90.0 wt%, about 92.0 wt%, about 94.0 wt%, about 95.0 wt%, about 96.0 wt%, about 97.0 wt%, about 98.0 wt%, or about 99.0 wt%. The second polyethylene polymer may have an upper limit on the range of ethylene content of about 80.0 wt%, about 85.0 wt%, about 90.0 wt%, about 92.0 wt%, about 94.0 wt%, about 95.0 wt%, about 96.0 wt%, about 97.0 wt%, about 98.0 wt%, about 99.0 wt%, about 99.5 wt%, or about 100.0 wt%. Accordingly the second polyethylene polymer may have less than 30.0 wt% of polymer units derived from a C₃- C₂o olefin, preferably, an alpha-olefin, e.g., hexene or octene. The lower limit on the range of C₃-C₂o olefin content may be about 25.0 wt%, about 20.0 wt%, about 15.0 wt%, about 10.0 wt%, about 8.0 wt%, about 6.0 wt%, about 5.0 wt%, about 4.0 wt%, about 3.0 wt%, about 2.0 wt%, about 1.0 wt%, or about 0.5 wt%. The upper limit on the range of C₃-C₂o olefin content may be about 20.0 wt%, about 15.0 wt%, about 10.0 wt%, about 8.0 wt%, about 6.0 wt%, about 5.0 wt%, about 4.0 wt%, about 3.0 wt%, about 2.0 wt%, or about 1.0 wt%. Any of the lower limits may be combined with any of the upper limits to form a range. Comonomer content is based on the total content of all monomers in the first polyethylene polymer.

[0037] The C₃ to C20 a-olefin comonomer may be linear or branched, and two or more comonomers may be used, if desired. Examples of suitable a-olefin comonomers include propylene, butene, 1 -pentene; 1 -pentene with one or more methyl, ethyl, or propyl substituents; 1-hexene; 1-hexene with one or more methyl, ethyl, or propyl substituents; 1- heptene; 1-heptene with one or more methyl, ethyl, or propyl substituents; 1-octene; 1-octene with one or more methyl, ethyl, or propyl substituents; 1-nonene; 1-nonene with one or more methyl, ethyl, or propyl substituents; ethyl, methyl, or dimethyl-substituted 1-decene; 1- dodecene, and styrene. Preferred a-olefins can comprise pentene, hexene, heptene, octene, or combinations thereof.

[0038] In various embodiments, the second polyethylene polymer is polymerized in the presence of a single-site catalyst. In a particular embodiment, the single-site catalyst is a metallocene. For example, the second polyethylene polymer may comprise a metallocene- catalyzed linear low density polyethylene (m-LLDPE). Useful metallocene catalysts, resins and methods of manufacture are described in U. S. Patent No. 6,932,592 entitled "Metallocene-Produced Very Low Density Polyethylenes" (Farley et al), which is hereby incorporated by reference for this purpose.

[0039] The second polyethylene polymers described herein are not limited by any particular method of preparation. In various embodiments, the ethylene-derived resin is produced by a gas-phase polymerization supported catalyst with a bridged bis(alkyl- substituted dicyclopentadienyl) zirconium dichloride transition metal component and methyl alumoxane cocatalyst.

[0040] In addition to those discussed above, second polyethylene polymers that are useful in this invention include copolymers commercially available from ExxonMobil Chemical Company in Houston, Texas, such as those sold under the trade designation EXCEED™, including but not limited to those available under grade name 0019XC.

Additional Components

[0041] In addition to the first and second polyethylene polymers, it will be understood that the tie layer and sealing layers described herein may comprise one or more additional polymeric components (e.g., a component comprising polyethylene, polypropylene and the like).

[0042] Polymer blends are also contemplated. For example, the tie layer or the sealing layer may comprise one or more additional LDPE resins, one or more additional resins other than LPDE, such as LLDPE, copolymer of vinyl acetate, methyl acetate, butyl acetate, acrylic acid and ionomer and terpolymer (such as those commercially available from ExxonMobil Chemical Company in Houston, Texas under the trade designation Escorene™ Ultra EVA, Optema™ EMA, ExxonMobil™ EnBA, Escor™ EAA, Iotek™ Ionomer), metallocene- catalyzed LLDPE, and polypropylene (such as those commercially available from ExxonMobil Chemical Company in Houston, Texas under the trade designation Vistamaxx™).

[0043] In various embodiments, one or more additives (i.e., additive package) may be included in the tie layer and/or the sealing layer. Such additives include for example, fillers, anti-blocking agents, slip additives, primary and secondary antioxidants (e.g., hindered phenolics such as IRGANOX™ 1010 or IRGANOX™ 1076 available from Ciba-Geigy), anti-cling additives, UV stabilizers, heat stabilizers, plasticizers, release agents, anti-static agents, pigments, colorants, dyes, waxes, silica, talc, processing aids and the like. The additive can be added through masterbatch of the additive and a polyethylene, for example LDPE or LLDPE. Laminate Material

[0044] In various embodiments, the present laminate material comprises a substrate layer, a tie layer and a sealing layer. The tie layer is placed in between the substrate layer and the sealing layer. Both the tie layer and the sealing layer are co-extrusion coated onto the substrate layer.

[0045] The substrate layer can comprise paper, wood, fabric, plastic layer and metal foil, for example, paperboard, polyolefin films, such as, PET layer, PE film, BOPP film, aluminum foil etc.

[0046] The substrate layer can be chemically treated. Any known technology applicable for chemical treatment of substrates, such as fibers, can be used in the present disclosure.

[0047] A primer can optionally be applied to the substrate. With the term "primer" in this disclosure is meant a polymeric material which contained oxygen and/or nitrogen atom containing moieties and is applied at low dry application weight of less than 1 g/m2 in a removable diluent. The primer increases the potential for reactive bonding of the tie layer and provides a clean contaminant free surface to assist the wetting out of the molten extruded tie layer and improve bonding at the chill roll. Chemical primers may be applied at lower dry application weights, e.g., 0.005 g/m². Primers can be solvent based, water-based, or solvent free, and can include polyurethanes, polyethylene-imine, polyesters, organo-functional amines and polyamides.

[0048] The tie layer, co-extrusion coated with the sealing layer onto the substrate layer, comprises the first polyethylene polymer. In various embodiments, the tie layer may comprise from about 70 to about 100 wt%, or from about 80 to about 100 wt%, or from about 90 to about 100 wt%, or about 100 wt% of the first polyethylene polymer based on the weight of the tie layer. Additives as aforementioned can be included in the tie layer in amount of less than about 10 wt%, or less than about 5 wt% based on the weight of the tie layer.

[0049] The sealing layer may comprise the second polyethylene polymer, and optionally the first polyethylene polymer. When the first polyethylene polymer is present, the sealing layer may comprise from about 5 to about 70 wt%, or from about 5 to about 50 wt%, or from about 5 to about 30 wt% of the first polyethylene polymer, and accordingly can comprise from about 30 to about 95 wt%, or from about 50 to about 95 wt%, or from about 70 to about 95 wt% of the second polyethylene polymer.

[0050] Additives can be added in each of the tie layer and sealing layer. In various embodiments, the amount of total additives present in each of the tie layer and the sealing layer is less than about 10 wt%, for example less than about 5 wt%, less than about 3 wt% based upon the weight of the tie layer or the sealing layer.

Composition Formation

[0051] The compositions of the layers described herein are not limited by any particular method of preparation, and may be formed using conventional or hereinafter devised equipment and methods, such as by dry compositioning the individual components and subsequently melt- mixing in a mixer, or by mixing the components directly together in a mixer (e.g., a Banbury mixer, a Haake mixer, a Brabender mixer, and/or dry mixer), or a single or twin-screw extruder, which may include a compounding extruder and/or a side-arm extruder used directly downstream of a polymerization process or on-line blending at the converter operation.

Co-Extrusion Coating Process

[0052] Any known extrusion coating process can be utilized to the present invention. In a typical extrusion coating process, resin is melted under heat and pressure in an extruder and the molten polymer is extruded through a slit die as a thin web. This web, at high temperature, is drawn down and coated onto a substrate in a nip-roll assembly formed by a water-cooled chill roll and a rubber-covered pressure roll. The combination is rapidly cooled by the chill roll and is taken up by a wind-up mechanism.

[0053] Co-extrusion is often used in combination with extrusion coating/lamination. In co-extrusion coating process, two or more layers of different polymers are extruded simultaneously through a single die. One benefit of co-extrusion is that separate laminating steps required to produce a complex multilayer laminate in for example adhesive lamination process can be combined into one step.

[0054] Co-extrusion dies are not particularly limited. In some embodiments, a feedblock die can be used. With this type of die, several melt streams fed from separate extruders can join within the die and be extruded as one web, and therefore more than two different polymers can be extruded simultaneously. In other embodiments, a dual slit die can be used.

With this type of die, two extruders feed through two separate channels in the die block and the two extruded webs meet at a nip where they are pressed onto the substrates.

[0055] Co-extrusion offers the possibilities of extruding a thin layer of a tie layer functioning as adhesion promoting in combination with a sealing layer.

Product Properties

[0056] In accordance with various embodiments, the laminate material formed in the present invention has one or more of the following properties (as determined by the procedures described herein):

(a) a hot tack plateau of greater than about 1.0 N/15 mm, or greater than about 1.8 N/15 mm, or greater than about 2.5 N/15 mm, or greater than about 3.0 N/15 mm, or greater than about 4.0 N/15 mm, or greater than about 5.0 N/15 mm;

(b) a seal initiation temperature (N/30 mm) of less than about 115°C, or less than about 110°C, or less than about 105°C;

(c) a seal strength of greater than about 4.0 N/15 mm, or greater than about 10.0 N/15 mm, or greater than about 15.0 N/15 mm, or greater than about 20.0 N/15 mm, or greater than about 30.0 N/15 mm, at a temperature of from about 115°C to about 160°C, or from about 120°C to about 150°C; and

(d) a coefficient of friction of less than about 0.50, or less than about 0.40, or less than about 0.30, or less than about 0.20.

[0057] In various embodiments, the products exhibit excellent adhesion between layers and/or good moisture blocking.

Examples

[0058] The advantages of the laminate materials described herein will now be further illustrated with reference to the following non-limiting examples.

Materials and Methods

[0059] The properties cited below were determined in accordance with the following test procedures. Where any of these properties is referenced in the appended claims, it is to be measured in accordance with the specified test procedure.

[0060] Hot Tack was determined by the method based on ASTM F- 1921.

[0061] Neck-In is the reduction of layer width, and was measured on an extruded polymer web and is equal to W0-W1, where W0 = width of the extrusion die and Wl = width of the polymer web actually coated on the substrate.

[0062] Seal Strength was determined by the method based on ASTM F-2029.

[0063] Adhesion strength was determined by a method based on ASTM D 1876.

[0064] Dynamic coefficient of friction was determined by a method based on ASTM D

1894.

[0065] Tensile strength at break, elongation at break, and 1% secant modulus were determined by a method based on ASTM D-882.

[0066] Puncture properties for Fmax and Energy to break were determined by a method based on ASTM D 5748.

[0067] Table 1 lists the components used in Examples 1 to 6. Table 1 : Materials used in Examples

Example 1

[0068] Corona- treated PET substrate was coated with primer- 1 and then extrusion coated through a Extrusion Coating Co-Extrusion line having two extruders for 2 coating layers - an inner tie layer (layer 1) and an outer sealing layer (layer 2) forming a three-layer laminate structure: 8 μιη PET (Corona treated, Primer- 1) / 7 gsm tie layer/ 8 gsm sealing layer. Co- extrusion coating configuration and compositions of the tie layer and the sealing layer are as follows:

Extruder maximum output: 100 Kg/hr

Die gap: 0.65 mm to 0.70 mm

Used die width: 1250 mm

Tie layer: 100 wt% PE2

Sealing Layer: 78 wt% PE1 + 17% PE2 + 5% SMB-1. Examples 2 - 3

[0069] Laminate structures in examples 2 and 3 were made using the same process as example 1, except that the following thickness and the compositions of the tie layer and sealing layer and the co-extrusion coating configuration were applied. [0070] Configuration of coating equipment of Examples 2 to 3 included:

Co-extrusion 2 layers

Maximum Line Speed: 200 m/min

Die gap: 0.65 mm to 0.70 mm

Max. die width: 1450 mm

Used die width: 1120 mm

Air gap: 165 mm.

[0071] Structure and Material of Example 2 were:

Structure: bare PET (Corona, Primer-2, 12 μιη) / tie layer (10 gsm) / sealing layer (10 gsm)

Tie layer: 86 wt% LDPE + 14 wt% WMB

Sealing layer: 66 wt% PE-1 + 20 wt% PE-3 + 10 wt% WMB + 4 wt%

SABMB-1.

[0072] Structure and Material of Example 3 were:

Structure: Reverse printed BOPP (Corona, Primer-2, 12 μιη) / tie layer (9 gsm) / sealing layer (9 gsm)

Tie layer: 86 wt% PE-3 + 14 wt% WMB

Sealing layer: 66 wt% PE-1 + 20 wt% PE-3 + 10 wt% WMB + 4% SABMB- 1.

Examples 4 - 7

[0073] Laminate structures in examples 4 to 7 were made using the same process as example 1, except that the following thickness and the compositions of the laminate material and co-extrusion coating configuration were applied.

[0074] Configurations of coating equipment of Examples 4, 5, and 6 included:

Co-extrusion: 2 layers

Used die width: 1400 mm

Max laminator speed: 450 meter/min

PET substrate: Corona treated.

[0075] Structure and Material of Example 4 were:

Structure: Reverse printed PET (12 μιη)/ ex-lam (8 gsm) / 8 μ met

PET (Corona, Primer- 3, 8 μιη) / tie layer (10 μιη) / sealing layer (8 μιη)

Tie layer: 100 wt% PE-3 Sealing layer: 80 wt% PE-1 + 14.5 wt% PE-3 + 4.5 wt% SMB-2 + 1%

ABMB-1.

[0076] Structure and Material of Example 5 were:

Structure: Reverse printed PET (Corona- oxidized by high voltage,

Primer-3, 12 μιη) / tie layer (10 μιη) / sealing layer (9 gsm)

Tie layer: 86 wt% PE-3 + 14 wt% WMB

Sealing layer: 70.5% PE-1 + 10 wt% PE-3 + 14 wt% WMB + 4.5 wt%

SMB-2 + 1 wt% ABMB-1.

[0077] Structure and Material of Example 6 were:

Structure: PET (12 μιη) / ex-lam (8 gsm) / met PET / (Corona,

Primer-3, 12 μιη) / tie layer (20 μιη) / sealing layer (20 μιη)

Tie layer: 100 wt% PE-3

Sealing layer: 80 wt% PE-1 + 15 wt% PE-3 + 3.5 wt% SMB-2 + 1.5 wt% ABMB-1.

Example 7

[0078] Example 7 was an adhesive lamination material having a structure of: plain PET (12 μιη) / adhesive-lamination (2.5 gsm) / met PET (Corona, Primer-3, 12 μιη) / sealing layer (20 μιη, PE blown film), which is typically used in the industry.

[0079] Various properties were measured according to the methods described herein and the results are shown in below Table 2 to 5.

Table 2: Processing conditions

NA: Not measured. Table 3: Sealing Strength, f_max (N/15 mm)

NA: Not measured.

Table 4: Properties

NA: Not measured. Table 5: Hot tack, f_max (N/15 mm)

NA: Not measured.

[0080] It can be seen from Table 2 that the processing parameters, of Examples 1 to 6 such as neck-in, melt temperature, were satisfactory for industrial application, and no surface defect during or after processing over the substrate was observed. In particular, the present invention, as demonstrated in Examples 1 to 6, showed a low neck-in values, which is particularly advantageous during extrusion coating because low thickness of the tie layer can be achieved due to good drawability, comparing to Example 7 (comparative), which has a polyethylene blow film thickness of 25 microns.

[0081] It can be seen from Table 5 that the present invention, as demonstrated by Examples 1 to 6, offers a low sealing initiation temperature while providing good hot tack and seal strength. That satisfies requirements regarding packet integrity for flexible packaging applications without producing blown or cast films first, as well as eliminating the adhesive lamination operation to have a sustainable solution while utilizing existing coating equipment.

[0082] It can also be seen from Tables 4 to 5 that the laminate material made by the present invention, as demonstrated in Examples 1 to 6, showed comparable properties as Example 7 that was prepared by adhesive lamination, such as tensile strength at break, elongation at break, 1% secant modulus, puncture properties, gloss, and hot tack force, which are useful for packaging performance. [0083] In particular, it can be seen from Table 4 that chemically treated substrates, as shown by Examples 1, and 4 to 6, have better adhesion compared to chemically untreated substrates, as shown by Examples 2 and 3; and that the addition of both slip additive and anti- block additives resulted in lower coefficient of friction (COF) values for Examples 4, 5, and 6 compared to Examples 1, 2, and 3.

[0084] The embodiments and tables set forth herein are presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and use the invention. However, those skilled in the art will recognize that the foregoing descriptions and tables have been presented for the purpose of illustration and example only. The description set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching without departing from the spirit and scope of the claims.

Claims

CLAIMS What is claimed is:

1. A laminate material, comprising:

a) a substrate layer;

b) a tie layer comprising a first polyethylene polymer having:

i) a density of about 0.911 to about 0.935 g/cm³;

ii) a branching index g'_Vi_S of about 0.05 to about 0.85;

iii) a melt index of from about 0.01 to about 15 g/10 min;

c) a sealing layer comprising a second polyethylene polymer and optionally the first polyethylene polymer, the second polyethylene polymer being a copolymer derived from ethylene and one or more C3 to C20 a-olefin comonomers and having:

i) a density of about 0.905 to about 0.926 g/cm³;

ii) a melt index of about 12 to about 35 g/ 10 min;

iii) a branching index g'_Vi_S of greater than about 0.85;

iv) a compositional distribution breadth index of about 60% to about 85%;

v) a molecular weight distribution of about 1.5 to about 4.0; and

wherein the tie layer and the sealing layer are co-extrusion coated onto the substrate layer.

2. The laminate material of claim 1, wherein the sealing layer comprises from about 5 to about 70 wt% of the first polyethylene polymer and from about 30 to about 95 wt% of the second polyethylene polymer, based on the total weight of the sealing layer.

3. The laminate material of claim 1 or 2, wherein the sealing layer comprises from about 5 to about 30 wt% of the first polyethylene polymer and from about 70 to about 95 wt% of the second polyethylene polymer, based on the total weight of the sealing layer.

4. The laminate material of any one of claims 1 to 3, wherein the first polyethylene polymer has a melt index of from about 0.05 to about 12 g/10 min.

5. The laminate material of any one of claims 1 to 4, wherein the first polyethylene polymer is a low density polyethylene polymer produced by a high pressure process.

6. The laminate material of any one of claims 1 to 5, wherein the second polyethylene polymer has a density of about 0.915 to about 0.920 g/cm³.

7. The laminate material of any one of claims 1 to 6, wherein the second polyethylene polymer is a metallocene catalyzed linear low density polyethylene.

8. The laminate material of any one of claims 1 to 7, wherein the second polyethylene polymer has the melt index of from about 15 to about 25 g/10 min.

9. The laminate material of any one of claims 1 to 8 wherein the a-olefin is selected from a group consisting of pentene, hexene, heptene, octene, or combinations thereof.

10. The laminate material of any one of claims 1 to 9, wherein the sealing layer further comprises less than about 5.0 wt% of a slip additive and/or antiblock additive based on the total weight of sealing layer.

11. The laminate material of any one of claims 1 to 10, wherein the substrate layer is selected from a group consisting of paper, wood, fabric, plastic layer, metal foil, and combinations thereof.

12. The laminate material of any one of claims 1 to 11, wherein the substrate layer is chemically treated.

13. The laminate material of any one of claims 1 to 12, wherein the substrate layer is a PET, polyethylene film, or polypropylene film.

14. The laminate material of any one of claims 1 to 13, wherein the material has a seal initiation temperature, as measured based on method ASTM F-2029, of less than about 110°C.

15. The laminate material of any one of claim 1 to 14, wherein the material has a seal strength, as measured based on the method ASTM F-2029, of greater than about 4.0 N/15 mm at a temperature of from about 115°C to about 160°C.

16. The laminate material of any one of claim 1 to 14, wherein the material has a seal strength, as measured based on the method ASTM F-2029, of greater than about 10.0 N/15 mm at a temperature of from about 115°C to about 160°C.

17. The laminate material of any one of claims 1 to 15, wherein the material has at a hot tack plateau, as measured based on the method ASTM F-1921, of greater than about 1.0 N/15 mm at a seal temperature of from about 100°C to about 150°C.

18. The laminate material of any one of claims 1 to 17, wherein the material has a dynamic coefficient of friction, as measured based on method ASTM D-1894, of less than about 0.5.

19. A process for making a laminate material, comprising the steps of:

(a) providing a substrate layer;

(b) co-extrusion coating a tie layer and a sealing layer onto the substrate layer to form the laminate material;

wherein the tie layer comprises a first polyethylene polymer having:

i) a density of about 0.911 to about 0.935 g/cm³;

ii) a branching index g'_Vi_S of about 0.05 to about 0.85;

iii) a melt index of from about 0.01 to about 15 g/10 min;

wherein the sealing layer comprises a second polyethylene polymer, and optionally the first polyethylene polymer, the second polyethylene polymer being a copolymer derived from ethylene and one or more C3 to C20 a-olefin comonomers and having:

i) a density of about 0.905 to about 0.926 g/cm³;

ii) a melt index of about 12 to about 35 g/10 min;

iii) a branching index g'_Vi_S of greater than about 0.85;

iv) a compositional distribution breadth index of about 60% to about 85%;

v) a molecular weight distribution of about 1.5 to about 4.0.

20. The process of claim 19, wherein the sealing layer comprises from about 5 to about 30 wt% of the first polyethylene polymer and from about 70 to about 95 wt% of the second polyethylene polymer, based on the total weight of the sealing layer.

21. The process of claim 19 or 20, wherein the first polyethylene polymer is a low density polyethylene polymer produced by a high pressure process.

22. The process of any one of claims 19 to 21, wherein the second polyethylene polymer is a metallocene catalyzed linear low density polyethylene.

23. The process of any one of claims 19 to 22, wherein the sealing layer further comprises less than about 5.0 wt% of a slip additive and/or antiblock additive based on the total weight of sealing layer.

24. The process of any one of claims 19 to 23, wherein the substrate is a chemically treated PET, polyethylene film, or polypropylene film.

25. The process of any one of claims 19 to 24, wherein the processing temperature for the tie layer during extrusion is higher than that of the sealing layer.