Laminate with excellent barrier properties and method for preparing the same

Abstract

A laminate, an article including the laminate, and a method for preparing the laminate are provided. The present disclosure relates to a laminate comprising a first substrate including a metallized polyethylene-based (PE-based) film, a second substrate including a polyethylene terephthalate-based film or a polypropylene-based film, and an adhesive layer for adhering the first substrate to the second substrate, the adhesive layer being derived from a two-component solvent-based polyurethane adhesive composition, the concentration of fatty acid or fatty acid derivative in the metallized PE-based film being less than 300 ppm based on the total weight of the metallized PE-based film, the two-component solvent-based polyurethane adhesive composition comprising a polyester polyol component and a polyisocyanate component, the polyester polyol component having about 40% by weight to 60% by weight of aromatic rings in the main chain based on the total weight of the polyester polyol, a molecular weight (Mw) of 5000 to 50000, and a weight ratio of the polyester polyol component to the polyisocyanate component being 100:5 to 100:30.

Description

[Technical Field]

[0001] This disclosure relates to laminates, articles containing laminates, and methods for preparing laminates. The laminates exhibit excellent barrier properties. [Background technology]

[0002] Today, market trends such as consumer demand, food safety, and e-commerce are increasing the demand for functional packaging, which requires higher-performance packaging structures that extend shelf life and / or improve packaging integrity. Therefore, these changes are driving the rapid growth of the market for high-barrier films, which provide crucial protection for contents from the external environment to ensure a longer shelf life.

[0003] In the flexible packaging industry, polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) are typical materials for base films that provide desired mechanical and barrier properties. PET or PP films, possessing high rigidity, good optical properties, and heat resistance, are widely used as printing substrates and as skin layers for laminate films. PE films, on the other hand, typically have better toughness and heat-seal properties than PET or PP and are very common as inner heat-seal layers in laminated films. However, based on their polymer properties, PET, PP, and PE films typically cannot provide the desired high oxygen barrier, which is crucial for protecting delicate contents such as certain meats, candies, snacks, or cookies. Therefore, while various approaches exist in the industry to achieve barrier performance, such as incorporating polymer barrier resins by co-extrusion, vacuum metallization onto film substrates, or coating of barrier materials onto film surfaces, achieving high barrier performance in laminates with respect to oxygen permeability (OTR) remains a challenge in the packaging industry.

[0004] For the reasons stated above, the packaging industry still needs to develop packaging materials with superior barrier properties. [Overview of the Initiative]

[0005] This disclosure provides a unique laminate exhibiting excellent barrier performance, an article containing the laminate, and a method for preparing the laminate.

[0006] In the first aspect, the present disclosure relates to a laminate, A first substrate containing a metallized polyethylene (PE) film, A second substrate comprising a polyethylene terephthalate (PET) film or a polypropylene (PP) film, An adhesive layer for bonding a first substrate to a second substrate, comprising an adhesive layer derived from a two-component solvent-based polyurethane adhesive composition, The concentration of fatty acids or fatty acid derivatives in the metallized PE film is less than 300 ppm based on the total weight of the metallized PE film. A two-component solvent-based polyurethane adhesive composition comprises a polyester polyol component and a polyisocyanate component. The polyester polyol component has approximately 40% to 60% by weight of aromatic rings in its main chain, based on the total weight of the polyester polyol, and its molecular weight (Mw) is 5,000 to 50,000. The present invention provides a laminate in which the weight ratio of polyester polyol component to polyisocyanate component is 100:5 to 100:30.

[0007] In a second aspect, the Disclosure provides an article comprising a laminate of the Disclosure.

[0008] In a third aspect, the present disclosure is a method for preparing a laminate of the present disclosure, 1) To provide a first substrate containing a metallized PE film and a second substrate containing a PET film or a PP film, 2) The method includes bonding a first substrate to a second substrate by using a two-component solvent-based polyurethane adhesive composition. The concentration of fatty acids or fatty acid derivatives in the metallized PE film is less than 300 ppm based on the total weight of the metallized PE film. A two-component solvent-based polyurethane adhesive composition comprises a polyester polyol component and a polyisocyanate component. The polyester polyol component has 40% to 60% by weight of aromatic rings in the main chain, based on the total weight of the polyester polyol, and has an Mw of 5,000 to 50,000. The present invention provides a method in which the weight ratio of the polyester polyol component to the polyisocyanate component is 100:5 to 100:30. [Modes for carrying out the invention]

[0009] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art in which the present invention pertains. Furthermore, all publications, patent applications, patents, and other references referenced herein are incorporated by reference.

[0010] As disclosed herein, all extents include endpoints unless otherwise indicated.

[0011] According to one embodiment of the present disclosure, the adhesive composition is a "two-component" or "two-part" composition comprising a polyester polyol component and a polyisocyanate component. According to another embodiment, the polyester polyol component and the polyisocyanate component are packaged, transported, and stored separately and combined immediately before or just before use for the manufacture of a laminate.

[0012] "Polyethylene polymer," "polyethylene-based polymer," "PE-based polymer," "polyethylene," or "ethylene-based polymer" means a polymer containing the majority of units derived from ethylene monomers (>50 mol%, or >60 mol%, or >70 mol%, or >80 mol%, or >90 mol%, or >95 mol%, or >97 mol%). This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of polyethylene known in the art include, but are not limited to, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (ULDPE), very low-density polyethylene (VLDPE), single-site catalyst linear low-density polyethylene (m-LLDPE) including both linear low-density resins and substantially linear low-density resins, medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). These polyethylene materials are generally well known in the art. However, the following description may be helpful in understanding the differences between some of these different polyethylene resins.

[0013] The term “LDPE” may also be referred to as “high-pressure ethylene polymer” or “highly branched polyethylene,” but is defined to mean that the polymer is partially or completely homopolymerized or copolymerized in an autoclave or tubular reactor at a pressure exceeding 14,500 psi (100 MPa) using a free radical initiator such as a peroxide (see, for example, U.S. Patent No. 4,599,392, incorporated herein by reference). LDPE resins typically have a density in the range of 0.916 to 0.935 g / cm³.

[0014] The term "LLDPE" includes both resins made using single-site catalysts including, but not limited to, traditional Ziegler-Natta catalyst systems and chromium-based catalysts, as well as bis-metallocene catalysts (sometimes referred to as "m-LLDPE") and constrained geometry catalysts, and includes linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains fewer long-chain branches than LDPE, and includes substantially linear ethylene polymers as further defined in U.S. Patent Nos. 5,272,236, 5,278,272, 5,582,923, and 5,733,155; homogeneously branched linear ethylene polymer compositions such as those of U.S. Patent No. 3,645,992, heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent No. 4,076,698, and / or blends thereof (such as those disclosed in U.S. Patent No. 3,914,342 or 5,854,045). LLDPE can be made via gas phase, solution phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0015] The term "MDPE" refers to polyethylene having a density of from 0.926 to 0.935 g / cm3. "MDPE" is typically made using chromium or Ziegler-Natta catalysts, or single-site catalysts including, but not limited to, bis-metallocene catalysts and constrained geometry catalysts, and typically has a molecular weight distribution ("MWD") greater than 2.5.

[0016] The term "HDPE" generally refers to polyethylene having a density greater than about 0.935 g / cm3 up to about 0.970 g / cm3, prepared using single-site catalysts including, but not limited to, Ziegler-Natta catalysts, chromium catalysts, or bis-metallocene catalysts and constrained geometry catalysts.

[0017] The term "ULDPE" generally refers to polyethylene having a density of 0.880 to 0.912 g / cm3 prepared with a single-site catalyst, including but not limited to Ziegler-Natta catalysts, chromium catalysts, or bis-metallocene catalysts and constrained geometry catalysts.

[0018] "Polypropylene-based polymer", "PP-based polymer", or "polypropylene-based polymer" shall mean a polymer comprising a majority (>50 mol%, or >60 mol%, or >70 mol%, or >80 mol%, or >90 mol%, or >95 mol%) of units derived from propylene monomers.

[0019] "Polyethylene terephthalate-based polymer" or "PET-based polymer" shall mean a polymer comprising a majority (>50 wt%, or >60 wt%, or >70 wt%, or >80 wt%, or >90 wt%, or >95 wt%) of ethylene terephthalate.

[0020] A "polyolefin plastomer" may be a polyethylene plastomer or a polypropylene plastomer. Polyolefin plastomers include, for example, polymers produced using single-site catalysts such as metallocene and constrained geometry catalysts. Polyolefin plastomers have a density of 0.885 to 0.915 g / cm 3 3. All individual values and subranges from 0.885 g / cm 3 3 to 0.915 g / cm 3 3 are included herein and disclosed herein. For example, the density of the plastomer can be from an upper limit of 0.895, 0.900, or 0.905 g / cm 3 3 to a lower limit of 0.905, 0.910, or 0.915 g / cm 3 3. In some embodiments, the polyolefin elastomer has a density of 0.890 to 0.910 g / cm 3 3.

[0021] The "polyolefin elastomer" may be a polyethylene elastomer or a polypropylene elastomer. The polyolefin elastomer has a density of 0.857 to 0.885 g / cm 3 . All individual values and subranges from 0.857 g / cm 3 to 0.885 g / cm 3 are included herein and disclosed herein. For example, the density of the low-density polyethylene can be from a lower limit of 0.857, 0.860, 0.865, 0.870, or 0.875 g / cm 3 to an upper limit of 0.870, 0.875, 0.880, or 0.885 g / cm 3 . In some embodiments, the polyolefin elastomer has a density of 0.860 to 0.880 g / cm 3 .

[0022] "Polyethylene-based film" or "PE-based film" refers to a film comprising at least 90 weight percent polyethylene, at least 95 weight percent polyethylene, or at least 97 weight percent polyethylene, based on the total weight of the film.

[0023] "Polypropylene-based film" or "PP-based film" refers to a film comprising at least 90 weight percent polypropylene, at least 95 weight percent polypropylene, or at least 97 weight percent polypropylene, based on the total weight of the film.

[0024] "Polyethylene terephthalate-based film" or "PET-based film" refers to a film comprising at least 90 weight percent polyethylene terephthalate, at least 95 weight percent polyethylene terephthalate, or at least 97 weight percent polyethylene terephthalate, based on the total weight of the film.

[0025] First substrate The first substrate comprises a metallized PE-based film. The metallized PE-based film comprises a PE-based film and a metal layer.

[0026] The PE film in the metallized PE film has at least one layer containing polyethylene. One layer containing polyethylene may be provided. Alternatively, two or more layers containing polyethylene may be provided. These two or more layers can be extruded together to form a PE film. Three (or more) layers containing polyethylene may be provided. When three (or more) layers containing polyethylene are provided, the layer adjacent to the metal layer is referred to herein as the skin layer, the layer on the outer side of the PE film opposite the metal layer is referred to as the sealant layer, and one or more layers between the skin layer and the sealant layer are one or more core layers. If only one layer containing polyethylene is provided, any of the polyethylene compositions described herein as the skin layer, core layer, or sealant layer may be used. If only two layers containing polyethylene are provided, any combination of the skin layer and core layer, the skin layer and sealant layer, or the core layer and sealant layer may be used. When two or more polyethylene-containing layers are provided, each polyethylene-containing layer may be directly adjacent to at least one other polyethylene-containing layer, or an adhesive layer or other intermediate layer may be used between the two or more polyethylene-containing layers. In one embodiment, the PE film in the metallized PE film includes a sealant layer. In one embodiment, the PE film in the metallized PE film includes a skin layer, a core layer, and a sealant layer.

[0027] The PE film in the metallized PE film may include linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), and combinations of two or more of the aforementioned. Preferably, the PE film in the metallized PE film may include a Ziegler-Natta catalyst, a single-site catalyst (not limited to metallocenes), or a chromium catalyst linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), autoclavable or tubular low-density polyethylene (LDPE), and combinations of two or more of the aforementioned.

[0028] The PE film in the metallized PE film may further include at least one of the following: ultra-low density polyethylene, polyolefin plastomer, polyolefin elastomer, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene vinyl alcohol, and any polymer containing at least 50% ethylene monomer, as well as combinations thereof.

[0029] The skin layer may include linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), and combinations of two or more of the above, preferably linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or combinations thereof. This LLDPE may be single-site catalyzed polyethylene (such as m-LLDPE, but not limited thereto). The skin layer may further contain additives such as antioxidants, UV stabilizers, heat stabilizers, lubricants, anti-tack agents, pigments or colorants, processing aids, crosslinking catalysts, flame retardants, fillers, and foaming agents. When used in combination with a core layer or sealant layer, the skin layer is metallized and, in that case, advantageously does not contain lubricants, but may contain anti-tack agents (e.g., talc, silicon dioxide, etc.), antioxidants, and processing aids. In one embodiment, additives such as lubricants and anti-tack agents are typically not used in the skin layer.

[0030] The core layer may include linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), and combinations of two or more of the aforementioned. Preferably, the core layer may include medium-density polyethylene (MDPE), high-density polyethylene (HDPE), or a combination thereof. The core layer may also contain additives as described for the skin layer. Preferably, additives such as lubricants and anti-tacks are not typically used in the core layer. This layer may be adjacent to the skin layer, on the opposite side from the metal layer in the skin layer.

[0031] The sealant layer may include linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyolefin elastomers or plastomers, and two or more combinations thereof. Preferably, the sealant layer may include a Ziegler-Natta catalyst, a single-site catalyst (containing metallocene), or a chromium catalyst linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), autoclaved or tubular low-density polyethylene (LDPE), and two or more combinations thereof, preferably linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or a combination thereof. LLDPE may be single-site catalyzed polyethylene (such as mLLDPE). This may be the outer layer of the film. The sealant layer may also advantageously contain an anti-tack agent. For example, an anti-tack agent may be present in the sealant layer in an amount of at least about 200 ppm, at least about 1000 ppm, or at least about 1500 ppm, preferably about 6000 ppm or less, or about 5000 ppm or less. Furthermore, a lubricant (e.g., erucamide) may be useful. For example, the lubricant may be present in the sealant layer in an amount of less than 500 ppm, or less than 300 ppm, or less than 200 ppm, less than 100 ppm, preferably less than 50 ppm, or equal to 0 ppm, based on the total weight of the sealant layer.

[0032] The PE film in the metallized PE film may be a blown film, a cast film, a longitudinally oriented film, or a biaxially oriented film. The PE film for the metallized PE film layer can be manufactured by blowing, casting, water cooling, double bubble, or other techniques known to those skilled in the art, as described in Film Processing Advances, Toshitaka Kanai and Gregory A. Campbell (eds.), Chapter 7 (Biaxial Oriented Film Technology), pp. 194-229. In some embodiments, after manufacturing, the film may be subjected to a longitudinally oriented (MDO) or biaxially oriented process to provide a longitudinally oriented film or a biaxially oriented film, respectively.

[0033] The PE film in the metallized PE film layer can be metallized by any known method for metallizing polyethylene film. For example, the metal layer can be applied using vacuum metallization. This may involve providing a metal source and evaporating it in a vacuum environment to condense it on the surface of the film. The metal is deposited on the skin layer of the PE film.

[0034] Suitable metals include Al, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, or their oxides. In some embodiments, the metal layer can be formed from aluminum or aluminum oxide (Al2O3).

[0035] After metallization, the metallized PE film can be easily stored in roll form. In this process, the metallized surface layer is in contact with the polyethylene layer on the opposite side of the film.

[0036] The overall thickness of the metallized film may be at least 10 microns, at least 20 microns, or at least 30 microns. The total thickness of the metallized film according to a particular embodiment may be 200 microns or less, 150 microns or less, 120 microns or less, 100 microns or less, 80 microns or less, 70 microns or less, or 60 microns or less.

[0037] Metallized PE films can have an optical density (OD) of at least 1.5, or at least 1.8, and 4.0 or less, 3.5 or less, or 3.0 or less. In some embodiments, the OD is 2.0. The optical density of a metallized PE film (for example, a multilayer structure comprising a polyethylene film on which a metal layer is deposited) can be measured using an optical densimeter (model number LS177, manufactured by Shenzhen Linshang Technology).

[0038] The metallized PE film can retain a surface energy of at least 34 dynes / cm, at least 38 dynes / cm, at least 40 dynes / cm, at least 42 dynes / cm, or at least 46 dynes / cm on the metallized surface for at least one week or at least two weeks after metallization.

[0039] Metallized PE films can be characterized by the absence (0 ppm) or substantial absence of fatty acids or their derivatives. Such fatty acids or their derivatives that are absent or substantially absent include saturated fatty acids having an even number of carbon atoms from 4 to 28, such as stearic acid (18 carbon atoms) and palmitic acid (16 carbon atoms), as well as metal salts of each fatty acid, such as calcium stearate, zinc stearate, and calcium palmitate. Specifically, the concentration of fatty acids or their derivatives in a metallized PE film can be equal to 300 ppm or less, 250 ppm or less, 200 ppm or less, 100 ppm or less, or 50 ppm or less, or 0 ppm, based on the total weight of the metallized PE film.

[0040] The concentration of antioxidants in the metallized PE film layer is less than 3000 ppm, less than 2000 ppm, less than 1500 ppm, or less than 1300 ppm, based on the total weight of the metallized PE film.

[0041] additives Antioxidants are compounds included in polymer films to stabilize the polymer(s) or to prevent oxidative degradation of the polymer(s). Antioxidants are well known to those skilled in the art.

[0042] Anti-tack agents are compounds that minimize or prevent adhesion (i.e., bonding) between two adjacent layers of a film. Adhesion can cause problems, for example, during the unwinding of a film roll. The use of anti-tack agents is well known to those skilled in the art. Examples of suitable anti-tack agents include, but are not limited to, silica, talc, calcium carbonate, and combinations thereof.

[0043] Lubricants are compounds added to films to reduce friction between films and / or between films and equipment. Typical lubricants include migratory and non-migratory lubricants, which are well known to those skilled in the art.

[0044] adhesive layer The adhesive layer is derived from a two-component solvent-based polyurethane adhesive composition, which contains a polyester polyol component and a polyisocyanate component.

[0045] A. Polyester polyol component Polyester polyols are typically obtained by reacting a polyfunctional alcohol having 2 to 12 carbon atoms, preferably 2 to 10 carbon atoms, with a polyfunctional carboxylic acid having 2 to 12 carbon atoms, preferably 2 to 10 carbon atoms, or its anhydride / ester. Typical polyfunctional alcohols for preparing polyester polyols are preferably diols, triols, and tetraols, and may include ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, glycerol, erythritol, pentaerythritol, trimethylolbenzene, and any combination thereof. Typical polyfunctional carboxylic acids for preparing polyester polyols can be aliphatic, alicyclic, aromaticaliphatic, aromatic, or heterocyclic, and may be substituted with halogen atoms, for example, and / or saturated or unsaturated. Preferably, the polyfunctional carboxylic acid is selected from the group consisting of adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid, itaconic acid, malonic acid, 2-methylsuccinic acid, 3,3-diethylglutaric acid, 2,2-dimethylsuccinic acid, trimellitic acid, their anhydrides, and any combination thereof. Adipic acid or a mixture of adipic acid and isophthalic acid is preferred. In another embodiment, the polyester polyol has an OH value of 2 to 30 mg KOH / g, preferably 5 to 25 mg KOH / g, more preferably 8 to 20 mg KOH / g.

[0046] According to one embodiment of the present disclosure, the polyester polyol has a hydroxyl functional value within a numerical range obtained by combining any two of the above endpoints, or at least 1.8, or at least 1.9, or at least 2.0, or at least 2.1, or at least 2.2, or up to 2.3, or up to 2.4, or up to 2.5, or up to 2.6, or up to 2.7, or up to 2.8, or up to 2.9, or up to 3.0. The polyester polyol may have a molecular weight within a numerical range obtained by combining any two of the above endpoints, or 5,000 to 50,000 g / mol, or 5,500 to 30,000 g / mol, or 6,000 to 25,000 g / mol, or 10,000 to 15,000 g / mol. The above description of the origin, method of production, category, molecular structure, and various parameters of polyester polyols also applies to this second polyester polyol.

[0047] According to one embodiment of the present disclosure, the polyester polyol has an aromatic ring content of about 40% to about 60% by weight, or about 45% to about 55% by weight, or about 47% to about 55% by weight, based on the dry weight of the polyester polyol.

[0048] For example, in one exemplary embodiment, the polyester polyol content may be 40% to 85% by weight, or 50% to 80% by weight, or 60% to 77% by weight, or 65% to 75% by weight, based on the total weight of the polyurethane composition.

[0049] The solid content of the polyester polyol component can be 40-85% by weight, preferably 50-80% by weight, and more preferably 55-75% by weight. The solvent used for the polyester polyol may be ethyl acetate or MEK, or a combination thereof, preferably ethyl acetate.

[0050] B. Polyisocyanate components Polyisocyanates may contain any molecule having two or more isocyanate groups or mixtures thereof. Such polyisocyanates may be aliphatic, alicyclic, aromatic, or mixtures thereof. Polyisocyanates may have an average functionality of >2 or 2.5-10. A suitable example of a polyisocyanate is C2-C 12 Aliphatic diisocyanates, and their dimers and trimers, such as C2-C8 alkylene diisocyanates including tetramethylene diisocyanate and hexamethylene diisocyanate (HDI), 1,12-dodecane diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate, and 2-methyl-1,5-pentamethylene diisocyanate; C6-C 15 Alicyclic diisocyanates, and their dimers and trimers, for example, isophorone diisocyanate (IPDI) and dicyclohexyl methane diisocyanate (HMDI), 1,4-cyclohexane diisocyanate, and 1,3-bis-(isocyanatomethyl)cyclohexane; C6-C 12 Aromatic diisocyanates, and their dimers and trimers, e.g., toluene diisocyanate (TDI) and diphenyl methane diisocyanate (MDI); C7-C 15 Examples include aromatic aliphatic diisocyanates, as well as their dimers and trimers.

[0051] Preferably, the polyisocyanate includes aliphatic or aromatic polyisocyanates. More preferably, the polyisocyanate is a hexamethylene diisocyanate homopolymer, a hexamethylene diisocyanate adduct, an isophorone diisocyanate homopolymer, an isophorone diisocyanate adduct, toluene diisocyanate (TDI), a toluene diisocyanate (TDI) adduct, a diphenylmethane diisocyanate (MDI), a diphenylmethane diisocyanate (MDI) adduct, or a mixture thereof. Trimers (or isocyanurates) in polyisocyanates can be prepared by methods known in the art, for example, as disclosed in U.S. Patent Publication No. 2006 / 0155095(A1), by trimerizing an alicyclic diisocyanate (e.g., isophorone diisocyanate) in the presence of one or more trimerizing catalysts, such as tertiary amines or phosphines, or heterogeneous catalysts, and optionally in the presence of a solvent and / or auxiliary agents, such as a co-catalyst, preferably at high temperature, until a desired NCO content is reached, and then inactivating the catalyst using inorganic and organic acids, corresponding acid halides and alkylating agents, preferably by heating. Similarly, isocyanurate compositions containing isocyanurates from aliphatic diisocyanates can be formed by cyclizing an aliphatic diisocyanate in the presence of one or more trimerizing catalysts, and then inactivating the catalyst. Any isocyanurates can be further modified by conventional methods to contain urethane, urea, imino-s-triazine, uretonimine, or carbodiimide moieties. Preferably, polyisocyanates useful in the present invention are selected from the group consisting of aromatic diisocyanates, their dimers and trimers, or mixtures thereof.

[0052] A polyisocyanate useful in the present invention may comprise one or more polyisocyanate prepolymers, which can be formed by reaction with a monol, diol, diamine, or monoamine, and then modified by reaction with an additional isocyanate to form an allophanate or biuret-modified prepolymer. Such a prepolymer may further comprise a polyalkoxy or polyether chain. Alternatively, such a prepolymer may then be mixed with a trimerizing catalyst to obtain an allophanate or biuret-modified polyisocyanate composition. The preparation of such allophanate or biuret prepolymers and subsequent trimerization are known in the art; see, for example, U.S. Patents 5,663,272 and 6,028,158. Furthermore, suitable polyisocyanates may be modified with ionic compounds such as aminosulfonic acids.

[0053] Examples of commercially available polyisocyanates include Desmodur L75, N3300, N3600, and N3900 polyisocyanates, as well as Bayhydur XP 2655, 401-60, and 401-70 polyisocyanates (Covestro); Tolonate HDT, HDT-LV, and HDT-LV2, and Easyaqua L 600 polyisocyanate (Vencorex Chemicals); DURANATE TLA-100 and TMA-100 polyisocyanates (AsahiKASEI); and Aquolin 268, 269, and 270 polyisocyanates (Wanhua Chemicals).

[0054] The polyisocyanates useful in the present invention can be used alone before being mixed with the polyol component, or they can be diluted with one or more solvents to form a polyisocyanate solution. Such solvents (also called "diluting solvents") can reduce the viscosity of the polyisocyanate and are non-reactive with it. The solvent can be used in amounts of 5% to 150% by weight, 15% to 130% by weight, 20% to 120% by weight, or 30% to 100% by weight, based on the weight of the polyisocyanate. Suitable diluting solvents include, for example, ethyl acetate, butyl acetate, MEK, or mixtures thereof. The solid content of the polyisocyanate component can be 40 to 100% by weight, preferably 50 to 90% by weight, and more preferably 55 to 80%. The polyurethane adhesive composition of the present invention may contain several different polyisocyanates, and the equivalent ratio of the total number of isocyanate group equivalents in the polyisocyanate to the total number of hydroxyl group equivalents in the polyester polyol component may be in the range of, for example, 1:1 to 2.0:1, or 1:1 to 1.8:1, or 1:1 to 1.5:1, or 1:1 to 1.2:1. According to a preferred embodiment of the present disclosure, the amount of the polyisocyanate compound is appropriately selected such that the isocyanate groups are present in a stoichiometric molar amount relative to the total molar amount of hydroxyl groups contained in the polyester polyol component.

[0055] The polyurethane adhesive composition of the present invention may further contain conventional additives such as, for example, a catalyst for curing, a pigment, a light stabilizer, an ultraviolet (UV) absorbing compound, a leveling agent, a wetting agent, a dispersant, a neutralizing agent, an antifoaming agent, or a rheology modifier, or a mixture thereof. These additives may be present in amounts of 0 to 20% by weight or 1 to 10% by weight, based on the weight of the polyurethane composition.

[0056] According to one embodiment of the present disclosure, the weight ratio of the polyester polyol component to the polyisocyanate component is about 100:5 to about 100:30, preferably about 100:8 to about 100:25, and more preferably about 100:10 to about 100:20.

[0057] Polyurethane adhesives can be prepared by mixing a polyester polyol component and a polyisocyanate component, ensuring uniform mixing, and then adding a certain amount of solvent to achieve the desired solid content.

[0058] Second substrate The second substrate includes polyethylene terephthalate (PET) film or polypropylene (PP) film.

[0059] There are three common types of PP polymers: homopolymers, random copolymers, and block copolymers. Comonomers are typically used with ethylene or butylene. Sinopec Chemicals is a suitable supplier / product for PP.

[0060] The PP-based film may contain 50% to 100% by weight of PP components. Preferably, the PP-based film contains 70% to 99% by weight, preferably 80% to 95% by weight, or 90% to 98% by weight of PP components. The PP components consist of at least one PP polymer, and optionally two or more PP polymers (i.e., different grades of PP).

[0061] Preferably, the PP-based film contains 50% to 100% by weight of PP components, either homopolymer PP, random copolymer PP, or a combination thereof. Preferably, the PP-based film contains 100% by weight of PP components, either homopolymer PP or PP random copolymer.

[0062] An example of a PP grade is homopolymer PP. Preferably, homopolymer PP has a melt flow rate (230℃ / 2.16Kg) ("MFR") of 2.6 to 3.0 g / 10 min, preferably 2.7 to 2.9 g / 10 min, and more preferably about 2.8 g / 10 min. Preferably, homopolymer PP has a yield point tensile strength of 26 to 36 MPa, preferably 28 to 35 MPa, and more preferably about 30 MPa or more. Preferably, homopolymer PP has an isotactic index of 93% or more, more preferably 94% or more, even more preferably 95% or more, or 98% or less.

[0063] An example of a PP grade is random copolymer PP (RCPP). Preferably, RCPP has a melt flow rate (230℃ / 2.16Kg) ("MFR") of 2.6 to 3.0 g / 10 min, preferably 2.7 to 2.9 g / 10 min, and more preferably 2.8 g / 10 min. Preferably, random copolymer PP has a yield point tensile strength of 27 to 37 MPa, preferably 29 to 36 MPa, and more preferably 31 MPa or higher. Preferably, random copolymer PP contains an isotactic index of 96% or higher, more preferably 97% or higher, and even more preferably 98% or higher.

[0064] The PP-based film in the second substrate may be a blown film, a cast film, a longitudinally oriented film, or a biaxially oriented film. The PP-based film in the second substrate can be manufactured by blowing, casting, water cooling, double bubble, or other techniques known to those skilled in the art, as described in Film Processing Advances, Toshitaka Kanai and Gregory A. Campbell (eds.), Chapter 7 (Biaxial Oriented Film Technology), pp. 194-229. In some embodiments, after manufacturing, the film may be subjected to a longitudinally oriented (MDO) or biaxially oriented process to provide a longitudinally oriented film or a biaxially oriented film, respectively.

[0065] PET refers to polyethylene terephthalate. Polyethylene terephthalate can be obtained by conventional known methods of polycondensation of a diol component (i.e., ethylene glycol) and a dicarboxylic acid component (i.e., terephthalic acid). Specifically, it can be produced by a general melt polymerization method in which the diol component and the dicarboxylic acid component are esterified and / or transesterified, followed by polycondensation under reduced pressure, or by known solution heating dehydration condensation using an organic solvent.

[0066] The manufacturing process for PET may include longitudinally oriented film or biaxially oriented film.

[0067] The amount of diol component used in the production of PET is substantially equimolar to 100 moles of dicarboxylic acid or its derivative, but due to distillation that occurs during esterification and / or transesterification and / or polycondensation, it is usually in excess of 0.1 mol% to 20 mol%.

[0068] Furthermore, polycondensation is preferably carried out in the presence of a polymerization catalyst. The timing of the addition of the polymerization catalyst is not particularly limited as long as it is before polycondensation; it may be added when the raw materials are filled or when the reduced pressure is started.

[0069] The PET-based film or PP-based film in the second substrate may consist of 1 to 10 layers, 1 to 8 layers, or 1 to 5 layers.

[0070] Laminate The laminate is 1) A step of providing a first substrate containing a metallized PE film (as described above) and a second substrate containing a polyethylene terephthalate film or a polypropylene film (as described above), 2) A method comprising bonding a first substrate to a second substrate by using a two-component solvent-based polyurethane adhesive composition, The concentration of fatty acids or fatty acid derivatives in the metallized PE film is less than 300 ppm based on the total weight of the metallized PE film. A two-component solvent-based polyurethane adhesive composition comprises a polyester polyol component and a polyisocyanate component. The polyester polyol component has 40% to 60% by weight of aromatic rings in the main chain, based on the total weight of the polyester polyol, and has an Mw of 5,000 to 50,000. It can be prepared by a method in which the weight ratio of the polyester polyol component to the polyisocyanate component is 100:5 to 100:30.

[0071] The laminate of this disclosure, when measured using the test method described herein, yielded a yield of 2.3 cc / m² over 24 hours under conditions of 23°C and 0% relative humidity. 2 If the OTR is less than 2.0 cc / m³ in 24 hours, measured using the test method described herein. 2 Less than 1.9 cc / m³ in 24 hours 2 Less than 1.8 cc / m³ in 24 hours 2 It has the following OTR.

[0072] Laminates can be used to form articles such as packaging materials. Examples of packaging materials that can be formed from the laminates of the present invention may include flexible packaging, pouches, self-standing pouches, and ready-made packaging materials or pouches. The laminates of the present invention can be used for food packaging materials. Examples of foods that may be contained in such packaging materials include meat, cheese, cereals, nuts, juices, sauces, and the like. Such packaging materials can be formed using techniques known to those skilled in the art, based on the teachings herein and on the specific use of the packaging material (e.g., type of food, amount of food, etc.). [Examples]

[0073] Herein, some embodiments of the present invention will be described in the following examples. However, the scope of this disclosure is naturally not limited to the formulations shown in these examples. Rather, the examples are simply relating to the invention of this disclosure.

[0074] The raw materials used in the examples are listed in Table 1 below.

[0075] [Table 1]

[0076] * IPA stands for isophthalic acid, PA stands for phthalic acid, AdA stands for adipic acid, EG stands for ethylene glycol, DEG stands for diethylene glycol, SA stands for sebacic acid, and NPG stands for neopentyl glycol.

[0077] All PE-based films were manufactured by a blown process. The formulations are listed in Table 2. Film-1 and Film-2 had a thickness of 50 μm. Vacuum metallization was performed using an industrial metallization machine (Machine type K5 EXPERT, BOBST Company) with an OD of 2.0. MET-1 and MET-2 are symbols indicating metallized film-1 and film-2, respectively. Before adhesive lamination, the manufactured vacuum-deposited films were stored in film roll form for two weeks at 23°C and 50% humidity. The surface energy of the metal layer of metallized film-1 (MET-1) decreased to less than 34 dynes, while the surface energy of the metal layer of metallized film-2 (MET-2) remained above 46 dynes / cm. Subsequently, adhesive lamination was performed using a Nordmeccanica Labo-Combi 400 machine.

[0078] [Table 2]

[0079] Prior to adhesive lamination, the manufactured VMPE films were stored in film roll form for two weeks at 23°C and 50% humidity. The surface energy of the MET-1 metal layer decreased to less than 34 dynes, while the surface energy of the MET-2 metal layer remained above 46 dynes / cm. Subsequently, all VMPE films were laminated with PET film (thickness = 12 μm, product type: PET flat film, Anhui Guofeng Plastic Industry Co., Ltd.) or BOPP film (thickness = 18 μm, product type: PP, Guangdong Weifu Packaging Material Co., Ltd.) using the adhesives described in Tables 3 and 4. In addition, a three-layer laminated structure containing VMPET (thickness = 12 μm, product type: P11, Jiaxing Pengxiang Packaging Materials CO.) was prepared as shown in Table 3 for comparison.

[0080] As shown in Tables 3 and 4, all samples of the present invention have a lower OTR than the comparative samples. The results demonstrate a good synergistic effect between the adhesive having the chemical composition of the present invention and the VMPE film of the present invention, which has good surface energy for the metal layer, in terms of enhancing the oxygen barrier of the laminated structure.

[0081] Example 1

[0082] [Table 3] The total coating weight is 3.0 gsm.

[0083] Examples 1-1, 1-2, 1-3, and 1-4 used the two-component SB (solvent-based) PU adhesive and the metallized PE film (MET-2) of the present invention, and these showed good OTR results.

[0084] Examples 1-1, 1-2, and 1-4 used the same metallized PE film (MET-2) of the present invention, but they used a two-component SB PU adhesive which is polyester polyol-based but has either a lower aromatic ring main chain or an excessively high Mw, and are therefore outside the scope of the present invention. These examples showed inferior OTR compared to the examples of the present invention.

[0085] Comparative Examples 1-3 also used the same metallized PE film (MET-2) of the present invention, but used a two-component SB PU adhesive with a polyether polyol main chain instead of a polyester polyol main chain, and their OTR was not as good as that of the examples of the present invention.

[0086] Comparative Examples 1-5 were pure PET films without adhesive lamination and showed very high OTR results compared to the examples of the present invention, indicating that both metallization and adhesives are important for achieving good OTR.

[0087] Comparative Examples 1-6 were pure metallized PE films without lamination using adhesives, and showed very high OTR results compared to the examples of the present invention, indicating that adhesives are important for achieving good OTR.

[0088] Comparative Examples 1-7 were PE films without adhesive lamination and showed extremely high OTR results compared to the examples of the present invention, indicating that both metallization and adhesives are important for achieving good OTR.

[0089] Example 2

[0090] [Table 4] The total coating weight is 3.0 gsm.

[0091] Examples 2-1 and 2-2 used the two-component SB (solvent-based) PU adhesive and the metallized PE film (MET-2) of the present invention, respectively, and showed good OTR results.

[0092] Comparative Examples 2-1 and 2-2 used the adhesive of the present invention, but they used a different metallized PE film (MET-1) and showed inferior OTR results.

[0093] Comparative Examples 2-3 also used the same metallized PE film (MET-2) of the present invention, but used a two-component SB PU adhesive with a polyether polyol main chain instead of a polyester polyol main chain, and their OTR was not as good as that of the examples of the present invention.

[0094] Comparative Examples 2-4 also used the same metallized PE film (MET-2) of the present invention, but instead of the adhesive of the present invention, they used a polyacrylic WB adhesive, and these showed inferior OTR results.

[0095] Comparative Examples 2-5 used OPP / / VMPET / / PE and polyacrylic-based WB adhesives, which showed inferior OTR results.

[0096] Comparative Examples 2-6 used PET / / VMPET / / PE and polyacrylic WB adhesives, which showed inferior OTR results.

[0097] Comparative Example 2-7 was a PET film without lamination using adhesive, and showed a very high OTR result compared to the examples of the present invention.

[0098] Comparative Example 2-8 was an OPP film without lamination using adhesive, and showed a very high OTR result compared to the examples of the present invention.

[0099] Comparative Example 2-9 was a pure metallized PE film (MET-1) without lamination by adhesive, and showed a very high OTR result compared to the examples of the present invention.

[0100] Comparative Example 2-10 was a pure metallized PE film (MET-2) without lamination by adhesive, and showed a very high OTR result compared to the examples of the present invention.

[0101] Comparative Example 2-11 was a PE film without lamination using adhesive, and showed a very high OTR result compared to the examples of the present invention.

[0102] Standard process for preparing the polyester of the embodiment of the present invention (IE-PES) and the polyester of the comparative example (CE-PES): All raw materials (IPA, AdA, EG, and DEG, etc.) are placed in the reactor and heated to 100°C, held at this temperature for 30 minutes, then heated to 175°C and held for a further 45 minutes, then the temperature is increased to 225°C and held until the acid value is less than 25 mg KOH / g. Next, a vacuum (approximately 500 mmHg) is applied and held for 15-30 minutes. Then, the temperature is maintained and the vacuum is gradually reduced to approximately 200 mmHg. If the acid value is less than 10 KOH / g, the vacuum is reduced to approximately 50 mmHg, and if the acid value is less than 2 KOH / g, the vacuum is reduced to approximately 10 mmHg. Then, cooling is started to 160°C, the vacuum is broken with N2, and if the temperature is below 160°C, ethyl acetate is then added to achieve the desired solid content, and cooling is continued to 70°C for filling.

[0103] Preparation of polyurethane adhesive compositions Solvent-based (SB) adhesives were prepared according to the following procedure: A fixed amount of polyester polyol and co-reactant F were weighed, mixed together according to the designed mixing ratio, and then stirring was initiated. A calculated amount of ethyl acetate was added to achieve a 30% solids content, and stirring was continued to ensure that the adhesive was homogeneous. The prepared SB adhesives were subjected to a lamination process using a Nordmeccanica Labo-Combi 400 machine, and the dry coating weight was confirmed to be 3.0–3.5 gsm.

[0104] Solvent-free (SL) adhesive: A certain amount of NCO prepolymer and polyol coreactate is weighed and mixed together to obtain a homogeneous adhesive. The adhesive is then poured onto a coating roller on a Labo-Combi 400 machine from Nordmeccanica and laminated, ensuring that the dry coating weight is 1.8-2.0 gsm.

[0105] Water-based (WB) adhesive: The WB adhesive was directly laminated on a Labo-Combi 400 machine from Nordmeccanica to ensure a dry coating weight of 2.0–2.5 gsm.

[0106] Test method Oxygen transmission rate (OTR) Oxygen permeability was measured according to ASTM D-3985, using purified oxygen, at a temperature of 23°C and 0% relative humidity, using a MOCON OX-TRAN Model 2 / 21 measuring device. The sample barrier data was 200 cc / m³. 2 If the test is for more than one day, the test area should be 50 cm 2 5cm 2 To reduce the noise, a mask was applied, and data was obtained over a wider test range.

[0107] Optical Density (OD) Test The OD test was performed using a spectrophotometer (Type LS117, Shenzhen Linshang Technology Co., Ltd). The metallized film was placed between the photo-emitter and the receptor so that the metallized surface faced the emitter. The OD was read and recorded.

[0108] Surface energy test The test was based on the use of an ACCU DYNE TEST® marker pen with a valve tip applicator. The principle was to keep the test portion of the pen separate from the fluid reservoir portion of the pen.

[0109] The procedure for testing the dyne level using a pen was as follows:

[0110] Place the metallized film sample on a flat glass plate.

[0111] Record the ambient temperature and relative humidity. If the sample temperature differs from the ambient temperature, stabilize it.

[0112] At least three points across the entire sample; test points at 1 / 4, 1 / 2, and 3 / 4 of the way across the film section.

[0113] Wetness determination 1. Select a marker pen with a dyne level that appears to be slightly lower than the dyne level of the test sample.

[0114] 2. Press the tip of the applicator firmly onto the material until the tip is saturated with ink.

[0115] 3. With a light touch, draw the pen across the test sample in two or three parallel passes. Disregard the first pass. Evaluate only the last pass to wash away any contaminants from the tip and ensure that the test fluid layer is thin enough for accurate measurement.

[0116] 4. If the last ink swath (strip-shaped section) remains wet on the test sample for more than 3 seconds, repeat steps 2 and 3 using the next higher dyne level marker. If the last ink swath becomes spherical, tears apart, or shrinks into a fine wire within 1 second, repeat steps 2 and 3 using the next lower dyne level marker.

[0117] 5. If the ink swast is held for 1-3 seconds before it loses its integrity, the marker's dyne level will closely match the sample's dyne level. The corresponding pen value is then recorded.

[0118] Determination of fatty acid content The fatty acid content was analyzed by extracting additives from the film using CH2CI2, followed by filtration and analysis by LC-MS (liquid chromatography-mass spectrometry). Standard solutions were prepared with fatty acids in appropriate concentration ranges.

[0119] Determination of anti-tack agent content The anti-tack agent was analyzed by thermogravimetric (TGA) analysis. TGA was performed on a TA Q500 instrument. Film samples were tested in an N2 environment. The test protocol was as follows: Heat from 25°C to 800°C at a rate of -10°C / min. -800°C for 3 minutes (isothermal heating)

[0120] The weight of the residue was recorded as the amount of anti-sticking additive.

[0121] Determination of lubricant content and antioxidant content The content of lubricants and antioxidants was analyzed by the total dissolution method. Film samples were dissolved in 0.075% triethyl phosphite in o-xylene at 130°C. The solution was cooled, methanol was added, and then the mixture was stirred. After the solid settled, the solution was injected into a liquid chromatography (LC) autosampler for antioxidant analysis and a gas chromatography (GC) for lubricant analysis. This application also relates to the following aspects. (1) It is a laminate, A first substrate containing a metallized polyethylene (PE) film, A second base comprising polyethylene terephthalate film or polypropylene film Materials and, An adhesive layer for bonding the first substrate to the second substrate, comprising an adhesive layer derived from a two-component solvent-based polyurethane adhesive composition, The concentration of fatty acids or fatty acid derivatives in the metallized PE film is less than 300 ppm based on the total weight of the metallized PE film. The aforementioned two-component solvent-based polyurethane adhesive composition comprises a polyester polyol component and a polyisocyanate component. The polyester polyol component has approximately 40% to 60% by weight of aromatic rings in its main chain, based on the total weight of the polyester polyol, and has a molecular weight (Mw) of 5,000 to 50,000. A laminate in which the weight ratio of the polyester polyol component to the polyisocyanate component is 100:5 to 100:30. (2) The laminate according to (1), wherein the weight ratio of the polyester polyol component to the polyisocyanate component is 100:10 to 100:20. (3) The laminate according to (1), wherein the metallized PE film comprises a PE film and a metal layer. (4) The laminate according to (1), wherein the PE film in the metallized PE film includes a skin layer, a core layer, and a sealant layer. (5) The laminate according to (4), wherein the anti-tack agent is present in the sealant layer in an amount of at least 200 ppm based on the total weight of the sealant layer. (6) The laminate according to (4), wherein the lubricant is present in the sealant layer in an amount of less than 500 ppm based on the total weight of the sealant layer. (7) The laminate according to (1), wherein the metallized PE film has an optical density (OD) of at least 1.5 and 4.0 or less. (8) The laminate according to (1), wherein the concentration of the antioxidant in the metallized PE film layer is less than 3000 ppm based on the total weight of the metallized PE film. (9) The laminate according to (1), wherein the PE film in the metallized PE film layer is a blown film, a cast film, a longitudinally oriented film, or a biaxially oriented film. (10) The laminate according to (3), wherein the metal layer comprises Al, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, or an oxide thereof. (11) The laminate according to (1), wherein the PP-based film contains 50% to 100% by weight of PP components. (12) An article comprising a laminate as described in any of (1) to (11) above. (13) A method for preparing a laminate according to any of (1) to (11) above, 1) To provide a first substrate containing a metallized PE film and a second substrate containing a PET film or a PP film, 2) The first substrate is bonded to the second substrate by using a two-component solvent-based polyurethane adhesive composition. The concentration of fatty acids or fatty acid derivatives in the metallized PE film is less than 300 ppm based on the total weight of the metallized PE film, and the two-component solvent-based polyurethane adhesive composition comprises a polyester polyol component and a polyisocyanate component. The polyester polyol component has 40% to 60% by weight of aromatic rings in its main chain, based on the total weight of the polyester polyol, and its Mw is 5,000 to 50,000. A method wherein the weight ratio of the polyester polyol component to the polyisocyanate component is 100:5 to 100:30.

Claims

1. It is a laminate, A first substrate containing a metallized polyethylene (PE) film, A second substrate comprising a polyethylene terephthalate film or a polypropylene film, An adhesive layer for bonding the first substrate to the second substrate, comprising an adhesive layer derived from a two-component solvent-based polyurethane adhesive composition, The concentration of fatty acids or fatty acid derivatives in the metallized PE film is less than 300 ppm based on the total weight of the metallized PE film. The aforementioned two-component solvent-based polyurethane adhesive composition comprises a polyester polyol component and a polyisocyanate component. The polyester polyol component has 40% to 60% by weight of monomers having aromatic rings in its main chain, based on the total weight of the raw materials for the polyester polyol, and has a molecular weight (Mw) of 10,000 to 15,000. A laminate in which the weight ratio of the polyester polyol component to the polyisocyanate component is 100:10 to 100:

30.

2. The laminate according to claim 1, wherein the weight ratio of the polyester polyol component to the polyisocyanate component is 100:10 to 100:

20.

3. The laminate according to claim 1, wherein the metallized PE film comprises a PE film and a metal layer.

4. The laminate according to claim 1, wherein the PE film in the metallized PE film includes a skin layer, a core layer, and a sealant layer.

5. The laminate according to claim 4, wherein an anti-tack agent is present in the sealant layer in an amount of at least 200 ppm based on the total weight of the sealant layer.

6. The laminate according to claim 4, wherein the lubricant is present in the sealant layer in an amount of less than 500 ppm based on the total weight of the sealant layer.

7. The laminate according to claim 1, wherein the metallized PE film has an optical density (OD) of at least 1.5 and 4.0 or less.

8. The laminate according to claim 1, wherein the concentration of the antioxidant in the metallized PE film layer is less than 3000 ppm based on the total weight of the metallized PE film.

9. The laminate according to claim 1, wherein the PE film in the metallized PE film layer is a blown film, a cast film, a longitudinally stretched film, or a biaxially stretched film.

10. The laminate according to claim 3, wherein the metal layer comprises Al, Zn, Au, Ag, Cu, Ni, Cr, Ge, Se, Ti, Sn, or an oxide thereof.

11. The laminate according to claim 1, wherein the PP-based film contains 50% to 100% by weight of PP components.

12. An article comprising a laminate according to any one of claims 1 to 11.

13. A method for preparing a laminate according to any one of claims 1 to 11, 1) To provide a first substrate containing a metallized PE film and a second substrate containing a PET film or a PP film, 2) The first substrate is bonded to the second substrate by using a two-component solvent-based polyurethane adhesive composition. The concentration of fatty acids or fatty acid derivatives in the metallized PE film is less than 300 ppm based on the total weight of the metallized PE film. The aforementioned two-component solvent-based polyurethane adhesive composition comprises a polyester polyol component and a polyisocyanate component. The polyester polyol component has 40% to 60% by weight of monomers having aromatic rings in its main chain, based on the total weight of the raw materials for the polyester polyol, and its Mw is 10,000 to 15,000. A method wherein the weight ratio of the polyester polyol component to the polyisocyanate component is 100:10 to 100:30.

Images