Laminate and packaging material composed of the laminate

Abstract

To provide a laminate having printability and strength, with less environmental load.SOLUTION: A laminate at least includes a substrate and a heat seal layer of a heat sealable polyethylene layer. The substrate and the heat seal layer are configured with a same material. The substrate has received a drawing process. The same material is polyethylene. The substrate and the heat seal layer contain a biomass-derived polyethylene.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate and a packaging material comprising the laminate. [Background technology]

[0002] Polyethylene film is used in various packaging materials because it has moderate flexibility, excellent transparency, moisture resistance, chemical resistance, etc., and is inexpensive. In particular, polyethylene has a melting point of approximately 100 to 140°C, although this varies slightly depending on the type, so it is commonly used as a heat-sealable film in the packaging material field.

[0003] On the other hand, compared to other thermoplastic resin films, polyethylene film has poor rigidity, making it less suitable for printing and making it impossible to form clear images on its surface. Furthermore, polyethylene film does not have high strength and does not meet the durability required for the exterior packaging of packaging materials. Therefore, packaging materials are produced by laminating a resin film with excellent rigidity and strength, such as a polyester film or a nylon film, with a polyethylene film to form a laminate, and then heat-sealing the edges of the laminate so that the polyethylene film side of the laminate is on the inside (for example, JP 2005-104525 A).

[0004] In recent years, along with the growing demand for the creation of a recycling-oriented society, attempts have been made to recycle and reuse packaging materials. However, when different types of resin films are bonded together as described above, it is difficult to separate the resin films from each other, making them unsuitable for recycling. Therefore, there has been a demand for packaging materials that impose less burden on the environment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-104525 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to provide a laminate that has printability and strength and that has a low environmental impact. [Means for solving the problem]

[0007] The laminate of the present invention comprises at least a substrate and a heat-sealable polyethylene layer, the substrate and the heat-seal layer being made of the same material, the substrate being stretched, the same material being polyethylene, and the substrate and the heat-seal layer containing polyethylene derived from biomass.

[0008] In one embodiment, the content of biomass-derived polyethylene in the substrate and the heat seal layer is 50% by mass or more and 80% by mass or less.

[0009] In one embodiment, the stretching ratio in the machine direction (MD) of the substrate is 2 times or more and 10 times or less.

[0010] In one embodiment, the thickness of the substrate is 9 μm or more and 50 μm or less.

[0011] In one embodiment, the substrate has an image formed on at least one side.

[0012] In one embodiment, the substrate is made by a blown film molding process.

[0013] In one embodiment, the heat seal layer comprises at least one of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

[0014] The packaging material of the present invention is characterized by being composed of the above laminate. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a laminate that has printability and strength and that places little burden on the environment. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional schematic view showing one embodiment of a laminate according to the present invention. [Figure 2] 1 is a cross-sectional schematic view showing one embodiment of a laminate according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Laminate> The laminate according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the laminate 10 includes at least a substrate 20 and a heat seal layer 30 . In one embodiment, a polyethylene layer 40 comprising a vapor-deposited film is provided between the substrate 20 and the heat-sealable layer 30 . Each layer of the laminate will be described below.

[0018] <Base material> The substrate is stretched, and may be uniaxially stretched or biaxially stretched, but from the viewpoint of strength, biaxially stretched is preferred.

[0019] The stretching ratio in the machine direction (MD) of the substrate is preferably 2 to 10 times, and more preferably 3 to 7 times. This can further improve the printability and strength of the laminate. This can also improve the transparency of the substrate. The stretching ratio in the transverse direction (TD) is preferably 2 to 10 times, and more preferably 3 to 7 times. This can further improve the printability and strength of the laminate. This can also improve the transparency of the substrate.

[0020] The substrate is made of polyethylene, and includes polyethylene derived from biomass. The biomass-derived polyethylene contained in the substrate includes homopolymers of plant-derived ethylene derived from bioethanol obtained from plant raw materials, and copolymers of the plant-derived ethylene with other monomers.

[0021] Examples of homopolymer polyethylene include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). The substrate may contain two or more of these. Among these, high density polyethylene (HDPE) and medium density polyethylene (MDPE) are preferred from the viewpoint of printability, strength and heat resistance of the laminate, and medium density polyethylene is more preferred from the viewpoint of suitability for stretching. In the present invention, the high density polyethylene has a density of 0.945 g / cm 3 The above-mentioned medium-density polyethylene has a density of 0.925 to 0.944 g / cm 3 Low density polyethylene has a density of 0.900g / cm 3 More than 0.925g / cm 3 Ultra-low density polyethylene has a density of less than 0.900 g / cm 3 It refers to something less than.

[0022] Other monomers include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene.

[0023] The content of biomass-derived polyethylene in the substrate is preferably 50% by mass or more and 80% by mass or less, and more preferably 55% by mass or more and 70% by mass or less, which allows for a high biomass content and further reduces the environmental impact.

[0024] Plant-derived ethylene can be obtained by fermenting sugar liquid or starch obtained from plants such as sugarcane, corn, and sweet potato using microorganisms such as yeast to produce bioethanol, and then heating this in the presence of a catalyst.

[0025] Polyethylenes with different densities and branching levels as described above can be obtained by appropriately selecting a polymerization method. For example, it is preferable to use a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as the polymerization catalyst, and to carry out the polymerization in one stage or in two or more stages by any of gas phase polymerization, slurry polymerization, solution polymerization, and high-pressure ionic polymerization.

[0026] The single-site catalyst is a catalyst capable of forming a uniform active species, and is usually prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activating co-catalyst. Single-site catalysts are preferred because they have a more uniform active site structure than multi-site catalysts, making it possible to polymerize polymers with high molecular weights and highly uniform structures. Metallocene catalysts are particularly preferred as single-site catalysts. Metallocene catalysts are catalysts containing the following catalytic components: a transition metal compound of Group IV of the periodic table containing a ligand with a cyclopentadienyl skeleton, a co-catalyst, and optionally an organometallic compound and a carrier.

[0027] In the above-mentioned transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, the cyclopentadienyl skeleton is a cyclopentadienyl group, a substituted cyclopentadienyl group, or the like. The substituted cyclopentadienyl group has at least one substituent selected from a hydrocarbon group having 1 to 30 carbon atoms, a silyl group, a silyl-substituted alkyl group, a silyl-substituted aryl group, a cyano group, a cyanoalkyl group, a cyanoaryl group, a halogen group, a haloalkyl group, a halosilyl group, and the like. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may be bonded to each other to form a ring, such as an indenyl ring, a fluorenyl ring, an azulenyl ring, or a hydrogenated product thereof. The rings formed by bonding the substituents to each other may further have substituents.

[0028] In the transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, the transition metal can be zirconium, titanium, hafnium, etc., with zirconium and hafnium being particularly preferred. The transition metal compound typically contains two ligands having a cyclopentadienyl skeleton, and the ligands having the cyclopentadienyl skeleton are preferably bonded to each other via a bridging group. Examples of the bridging group include alkylene groups having 1 to 4 carbon atoms, silylene groups, substituted silylene groups such as dialkylsilylene groups and diarylsilylene groups, and substituted germylene groups such as dialkylgermylene groups and diarylgermylene groups. Substituted silylene groups are preferred. The above-mentioned transition metal compounds of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton can be used as a catalyst component, either singly or in combination.

[0029] The co-catalyst refers to a catalyst that can effectively use the above-mentioned transition metal compound of Group IV of the periodic table as a polymerization catalyst or that can balance the ionic charge in a catalytically activated state. Examples of the co-catalyst include benzene-soluble aluminoxanes of organoaluminum oxy compounds and benzene-insoluble organoaluminum oxy compounds, ion-exchangeable layered silicates, boron compounds, ionic compounds consisting of a cation with or without an active hydrogen group and a non-coordinating anion, lanthanoid salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing a fluoro group.

[0030] The transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton may be supported on an inorganic or organic support. The support is preferably a porous oxide of an inorganic or organic compound, and specific examples include ion-exchange layered silicates such as montmorillonite, SiO2, Al2O3, MgO, ZrO2, TiO2, BO3, CaO, ZnO, BaO, ThO2, and mixtures thereof. Furthermore, examples of organometallic compounds that may be used if necessary include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these, organoaluminum compounds are preferred.

[0031] Furthermore, commercially available biomass-derived polyethylene (for example, Green PE available from Braskem) may be used.

[0032] The substrate may contain polyethylene derived from a non-biomass source, provided that the properties of the present invention are not impaired. The substrate may also contain additives, such as crosslinkers, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0033] In one embodiment, the substrate has a multi-layer structure. In one embodiment, the substrate may have a structure including a layer made of high-density polyethylene (hereinafter referred to as high-density polyethylene layer) and a layer made of medium-density polyethylene (hereinafter referred to as medium-density polyethylene layer). By providing a high-density polyethylene layer on the outer side of the substrate, the strength and heat resistance of the laminate of the present invention can be further improved, and by providing a medium-density polyethylene layer, the stretchability of the substrate can be further improved.

[0034] For example, it has a structure consisting of a co-extruded film of a high density polyethylene layer and a medium density polyethylene layer from the outside. By adopting such a constitution, the stretchability of the film can be improved, and the strength and heat resistance of the laminate of the present invention can be improved. In this case, the thickness of the high density polyethylene layer is preferably thinner than the thickness of the medium density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 1 / 10 or more and 1 / 1 or less, and more preferably 1 / 5 or more and 1 / 2 or less. By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to be 1 / 10 or more, the strength and heat resistance of the laminate of the present invention can be further improved. Also, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to be 1 / 1 or less, the stretchability of the substrate can be further improved.

[0035] Alternatively, for example, the film may be constructed from a three-layer co-extruded film of a high density polyethylene layer, a medium density polyethylene layer and a high density polyethylene layer from the outside. By adopting such a configuration, the stretchability of the substrate can be further improved, the strength and heat resistance of the laminate of the present invention can be further improved, and the occurrence of curling in the substrate can be prevented. In this case, the thickness of the high density polyethylene layer is preferably thinner than the thickness of the medium density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 1 / 10 or more and 1 / 1 or less, and more preferably 1 / 5 or more and 1 / 2 or less. By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to be 1 / 10 or more, the strength and heat resistance of the laminate of the present invention can be further improved. Also, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to be 1 / 1 or less, the stretchability of the substrate can be further improved.

[0036] For example, the film may be configured as a five-layer co-extruded film consisting of, from the outside, a high-density polyethylene layer, a medium-density polyethylene layer, a low-density polyethylene layer, a linear low-density polyethylene layer or an ultra-low-density polyethylene layer (in this paragraph, for the sake of simplicity, these will be collectively referred to as low-density polyethylene layers), a medium-density polyethylene layer and a high-density polyethylene layer. By adopting such a configuration, the stretchability of the substrate can be improved, the strength and heat resistance of the laminate of the present invention can be improved, and the occurrence of curling in the substrate can be prevented. Furthermore, the production efficiency of the substrate can be improved as described below. In this case, the thickness of the high density polyethylene layer is preferably thinner than the thickness of the medium density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 1 / 10 or more and 1 / 1 or less, and more preferably 1 / 5 or more and 1 / 2 or less. By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to be 1 / 10 or more, the strength and heat resistance of the laminate of the present invention can be improved, and by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to be 1 / 1 or less, the stretchability of the substrate can be improved. The thickness of the high-density polyethylene layer is preferably the same as or greater than the thickness of the low-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer is preferably 1 / 0.25 or more and 1 / 2 or less, and more preferably 1 / 0.5 or more and 1 / 1 or less. By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer to 1 / 0.25 or more, heat resistance can be improved, and by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer to 1 / 1 or less, adhesion between the medium-density polyethylene layers can be improved. The thickness of each high-density polyethylene layer is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 10 μm or less. By making the thickness of the high-density polyethylene layer 1 μm or more, the strength and heat resistance of the laminate of the present invention can be further improved. Furthermore, by making the thickness of the high-density polyethylene layer 20 μm or less, the processability of the laminate of the present invention can be further improved. The thickness of the medium-density polyethylene layer is preferably 1 μm or more and 30 μm or less, and more preferably 5 μm or more and 20 μm or less. By making the thickness of the medium-density polyethylene layer 1 μm or more, the stretchability of the substrate can be further improved. Furthermore, by making the thickness of the medium-density polyethylene layer 30 μm or less, the processability of the laminate of the present invention can be further improved. The thickness of the low-density polyethylene layer is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 5 μm or less. By making the thickness of the low-density polyethylene layer 1 μm or more, the adhesion between the high-density polyethylene layer and the medium-density polyethylene layer can be further improved, and by making the thickness of the low-density polyethylene layer 5 μm or less, the processability of the laminate of the present invention can be further improved. In one embodiment, a substrate having such a configuration can be produced by, for example, an inflation method. Specifically, the film can be produced by co-extruding a high-density polyethylene layer, a medium-density polyethylene layer, and a low-density polyethylene layer, a linear low-density polyethylene layer, or an ultra-low-density polyethylene layer from the outside into a tubular shape, and then pressing the opposing low-density polyethylene layers, linear low-density polyethylene layers, or ultra-low-density polyethylene layers together using a rubber roll or the like. By using such a method, the number of defective products in the manufacturing process can be significantly reduced, and ultimately production efficiency can be improved. Furthermore, stretching can also be carried out in the inflation film-forming machine, which can further improve production efficiency.

[0037] In one embodiment, the film may be configured as a seven-layer co-extruded film consisting of, from the outside, a high-density polyethylene layer, a blend resin layer of high-density polyethylene and medium-density polyethylene, a medium-density polyethylene layer, a low-density polyethylene layer, a linear low-density polyethylene layer or an ultra-low-density polyethylene layer (in this paragraph, for simplicity, these are collectively referred to as low-density polyethylene layers), a medium-density polyethylene layer, a blend resin layer of high-density polyethylene and medium-density polyethylene, and a high-density polyethylene layer. This structure can improve the adhesion between the high-density polyethylene layer and the medium-density polyethylene layer, and can also improve the processability of the laminate of the present invention. The thickness of each high-density polyethylene layer is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 10 μm or less. By making the thickness of the high-density polyethylene layer 1 μm or more, the strength and heat resistance of the laminate of the present invention can be further improved. Furthermore, by making the thickness of the high-density polyethylene layer 20 μm or less, the processability of the laminate of the present invention can be further improved. The thickness of each blend resin layer of high-density polyethylene and medium-density polyethylene is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 10 μm or less. This improves adhesion between the high-density polyethylene layer and the medium-density polyethylene layer. It also improves the processability of the laminate of the present invention. The blend ratio of high-density polyethylene to medium-density polyethylene in the blend resin layer is preferably 1:9 to 9:1, more preferably 3:7 to 7:3, by mass, which can improve adhesion between the high-density polyethylene layer and the medium-density polyethylene layer and can also improve the processability of the laminate of the present invention. The thickness of the medium-density polyethylene layer is preferably 1 μm or more and 30 μm or less, and more preferably 5 μm or more and 20 μm or less. By making the thickness of the medium-density polyethylene layer 1 μm or more, the stretchability of the substrate can be further improved. Furthermore, by making the thickness of the medium-density polyethylene layer 30 μm or less, the processability of the laminate of the present invention can be further improved. The thickness of the low-density polyethylene layer is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 5 μm or less. By making the thickness of the low-density polyethylene layer 1 μm or more, the adhesion between the high-density polyethylene layer and the medium-density polyethylene layer can be further improved. Furthermore, by making the thickness of the low-density polyethylene layer 5 μm or less, the processability of the laminate of the present invention can be further improved. In one embodiment, the substrate having such a configuration can be produced by the inflation method described above. By using such a method, the number of defective products in the manufacturing process can be significantly reduced, and ultimately production efficiency can be improved. Furthermore, stretching can also be carried out in the inflation film-forming machine, which can further improve production efficiency.

[0038] The thickness of the substrate is preferably 9 μm or more and 50 μm or less, and more preferably 12 μm or more and 30 μm or less. By setting the thickness of the substrate within the above numerical range, the printability, strength, and heat resistance of the laminate can be further improved.

[0039] In one embodiment, the substrate has, on one surface thereof, a vapor-deposited film containing a metal such as aluminum or an inorganic oxide such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, or barium oxide, thereby improving the gas barrier properties of the laminate according to the present invention. As the vapor deposition method, a conventionally known method can be used, for example, physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, or chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0040] The thickness of the vapor-deposited film is preferably 0.002 μm or more and 0.4 μm or less, and more preferably 0.005 μm or more and 0.1 μm or less. By keeping the thickness of the vapor-deposited film within the above numerical range, it is possible to prevent the occurrence of cracks in the vapor-deposited film while maintaining gas barrier properties.

[0041] Alternatively, for example, a composite film consisting of two or more vapor-deposited layers of different inorganic oxides can be formed and used by combining physical vapor deposition and chemical vapor deposition. The vacuum level in the deposition chamber is preferably about 10-2 to 10-8 mbar, particularly about 10-3 to 10-7 mbar, before oxygen is introduced, and about 10-1 to 10-6 mbar, particularly about 10-2 to 10-5 mbar, after oxygen is introduced. The amount of oxygen introduced varies depending on the size of the deposition machine. An inert gas such as argon, helium, or nitrogen may be used as a carrier gas for the introduced oxygen, provided that no adverse effects occur. The film transport speed is preferably about 10 to 800 m / min, particularly about 50 to 600 m / min.

[0042] The substrate may have an image such as a letter, a pattern, a symbol, etc. formed on its surface. It is preferable to form the image on the side of the substrate where the heat seal layer is laminated, since this can prevent the image from deteriorating over time. The method for forming the image is not particularly limited, and examples thereof include conventionally known printing methods such as gravure printing, offset printing, flexographic printing, etc. Among these, flexographic printing is preferred from the viewpoint of environmental load.

[0043] The substrate can be obtained by melting a resin material containing polyethylene, forming it into a film by a melt extrusion molding method such as inflation molding or T-die molding, and then stretching it. Inflation molding is preferred because it allows for easier stretching. A substrate having a multilayer structure can be produced by melt co-extruding multiple resin materials.

[0044] The melt flow rate (MFR) of the resin material is preferably 0.5 g / 10 min or more and 20 g / 10 min or less, and more preferably 0.8 g / 10 min or more and 5 g / 10 min or less. By setting the MFR of the resin material within the above numerical range, the stretching process can be carried out more easily.

[0045] In one embodiment, the substrate may be provided with a barrier coat layer, which may improve oxygen and water vapor barrier properties. When the substrate has a vapor-deposited film, the barrier coat layer may be provided on or under the vapor-deposited film.

[0046] In one embodiment, the barrier coat layer contains a gas barrier resin such as ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyacrylonitrile, polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide (MXD6), polyester, polyurethane, and (meth)acrylic resin. Among these, polyvinyl alcohol is preferred from the viewpoint of oxygen barrier property and water vapor barrier property. Furthermore, when the substrate has a vapor-deposited film made of an inorganic oxide, the occurrence of cracks in the vapor-deposited film can be effectively prevented by including polyvinyl alcohol in the barrier coat layer.

[0047] The content of the gas barrier resin in the barrier coat layer is preferably 50% by mass or more and 95% by mass or less, and more preferably 75% by mass or more and 90% by mass or less. By making the content of the gas barrier resin in the barrier coat layer 50% by mass or more, it is possible to further improve the oxygen barrier property and water vapor barrier property.

[0048] The barrier coat layer may contain additives within the range that does not impair the characteristics of the present invention.

[0049] The thickness of the barrier coat layer is preferably 0.01 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less. By making the thickness of the barrier coat layer 0.01 μm or more, the oxygen barrier property and water vapor barrier property can be further improved, and by making the thickness of the barrier coat layer 10 μm or less, recyclability can be maintained.

[0050] The barrier coat layer can be formed by dissolving or dispersing the above-mentioned material in water or an appropriate solvent, applying the solution, and drying. Alternatively, the barrier coat layer can be formed by applying a commercially available barrier coating agent and drying it.

[0051] In another embodiment, the barrier coat layer is a gas barrier coating film containing at least one resin composition such as a hydrolyzate of a metal alkoxide or a hydrolyzed condensate of a metal alkoxide obtained by polycondensing a mixture of a metal alkoxide and a water-soluble polymer by a sol-gel method in the presence of a sol-gel catalyst, water, an organic solvent, etc. When the substrate has a vapor-deposited film made of an inorganic oxide, by providing a barrier coat layer of this type adjacent to the vapor-deposited film, it is possible to effectively prevent cracks from occurring in the vapor-deposited film.

[0052] In one embodiment, the metal alkoxide is represented by the following general formula: R 1 n M(OR 2 ) m (wherein, R 1 , R 2 each represents an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the valence of M.

[0053] As the metal atom M, for example, silicon, zirconium, titanium, aluminum, etc. can be used. Also, R 1 and R 2 Examples of the organic group represented by the formula (I) include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and an i-butyl group.

[0054] Examples of metal alkoxides that satisfy the above general formula include tetramethoxysilane (Si(OCH3)4), tetraethoxysilane (mass %) Si(OC2H5)4), tetrapropoxysilane (Si(OC3H7)4), and tetrabutoxysilane (Si(OC4H9)4).

[0055] It is also preferable to use a silane coupling agent together with the metal alkoxide. As the silane coupling agent, known organoalkoxysilanes containing organic reactive groups can be used, but organoalkoxysilanes having epoxy groups are particularly preferred. Examples of organoalkoxysilanes having epoxy groups include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0056] Two or more of the above silane coupling agents may be used, and the silane coupling agent is preferably used in an amount of about 1 to 20 parts by mass per 100 parts by mass of the total amount of the alkoxides.

[0057] As the water-soluble polymer, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are preferred, and from the viewpoints of oxygen barrier property, water vapor barrier property, water resistance and weather resistance, it is preferred to use these in combination.

[0058] The content of the water-soluble polymer in the gas barrier coating film is preferably 5 parts by mass or more and 500 parts by mass or less per 100 parts by mass of the metal alkoxide. By adjusting the content of the water-soluble polymer in the gas barrier coating film to 5 parts by mass or more per 100 parts by mass of the metal alkoxide, the oxygen barrier property and water vapor barrier property of the substrate can be further improved. Also, by adjusting the content of the water-soluble polymer in the gas barrier coating film to 500 parts by mass or less per 100 parts by mass of the metal alkoxide, the film formability of the gas barrier coating film can be improved.

[0059] The thickness of the gas barrier coating film is preferably from 0.01 μm to 100 μm, and more preferably from 0.1 μm to 50 μm, which allows for improved oxygen barrier properties and water vapor barrier properties while maintaining recyclability. By making the thickness of the gas barrier coating film 0.01 μm or more, the oxygen barrier property and water vapor barrier property of the substrate can be improved, and when the gas barrier coating film is provided adjacent to a vapor-deposited film made of an inorganic oxide, the occurrence of cracks in the vapor-deposited film can be prevented.

[0060] The gas barrier coating film can be formed by applying a composition containing the above-mentioned materials by a conventionally known means such as roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, or applicator coating, and then polycondensing the composition by a sol-gel method. The sol-gel catalyst is preferably an acid or an amine compound. As the amine compound, a tertiary amine that is substantially insoluble in water and soluble in an organic solvent is preferred, such as N,N-dimethylbenzylamine, tripropylamine, tributylamine, tripentylamine, etc. Among these, N,N-dimethylbenzylamine is preferred. The sol-gel catalyst is preferably used in the range of 0.01 to 1.0 part by mass, more preferably 0.03 to 0.3 part by mass, per 100 parts by mass of the metal alkoxide. By using a sol-gel catalyst in an amount of 0.01 part by mass or more per 100 parts by mass of metal alkoxide, the catalytic effect can be improved, and by using a sol-gel catalyst in an amount of 1.0 part by mass or less per 100 parts by mass of metal alkoxide, the thickness of the gas barrier coating film formed can be made uniform.

[0061] The composition may further contain an acid, which is used as a catalyst in the sol-gel process, mainly for the hydrolysis of alkoxides, silane coupling agents, and the like. The acid may be a mineral acid such as sulfuric acid, hydrochloric acid, or nitric acid, or an organic acid such as acetic acid or tartaric acid. The amount of the acid used is preferably 0.001 mol or more and 0.05 mol or less based on the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent. The catalytic effect can be improved by using an acid in an amount of 0.001 mole or more relative to the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent. Also, the thickness of the gas barrier coating film formed can be made uniform by using an acid in an amount of 0.05 mole or less relative to the total molar amount of the alkoxide and the alkoxide portion (e.g., silicate portion) of the silane coupling agent.

[0062] The composition preferably contains water in an amount of 0.1 to 100 moles, more preferably 0.8 to 2 moles, per mole of the total molar amount of the alkoxides. By adjusting the water content to 0.1 moles or more per mole of the total alkoxide amount, the oxygen barrier property and water vapor barrier property can be improved, and by adjusting the water content to 100 moles or more per mole of the total alkoxide amount, the hydrolysis reaction can be carried out quickly.

[0063] The composition may also contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butanol.

[0064] An embodiment of the method for forming a gas barrier coating film will be described below. First, a composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and optionally a silane coupling agent, etc. A polycondensation reaction gradually proceeds in the composition. The composition is then applied and dried by the conventional method described above, which further promotes the polycondensation reaction of the alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains one) to form a composite polymer layer. Finally, the composition is heated at a temperature of 20 to 250°C, preferably 50 to 220°C, for 1 second to 10 minutes to form a gas barrier coating film.

[0065] The barrier coat layer may have an image formed on its surface, and the method for forming the image is as described above.

[0066] <Heat seal layer> The heat seal layer is made of the same material as the base material, i.e., polyethylene, which can improve the recyclability of the laminate. The heat seal layer contains a biomass-derived polyethylene. Among the biomass-derived polyethylenes, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) are preferred from the viewpoint of heat sealability.

[0067] The content of biomass-derived polyethylene in the heat seal layer is preferably 50% by mass or more and 80% by mass or less, and more preferably 55% by mass or more and 70% by mass or less, which allows for a high biomass content, further reducing the environmental load, and preventing bleed-out onto the film surface.

[0068] The heat seal layer may contain polyethylene derived from a non-biomass material as long as the properties of the present invention are not impaired. It may also contain additives, such as crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0069] The thickness of the heat seal layer is preferably 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 150 μm or less. By setting the thickness of the heat seal layer within the above numerical range, the heat sealability can be improved.

[0070] The heat seal layer can be formed by producing a polyethylene film by forming a resin material containing polyethylene into a film using a melt extrusion molding method such as inflation molding or T-die molding, and then laminating this onto a polyethylene layer having a substrate or a vapor-deposited film via an adhesive layer. The adhesive layer comprises an adhesive, the adhesive comprising: The adhesive may be a one-component curing type, a two-component curing type, or a non-curing type. The adhesive may be a solvent-free adhesive or a solvent-based adhesive, but from the viewpoint of environmental load, a solvent-free adhesive is preferably used. Examples of solvent-free adhesives include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, and urethane adhesives, and among these, two-component curing urethane adhesives can be preferably used. Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and olefin-based adhesives.

[0071] Furthermore, when the substrate has an aluminum vapor-deposited film and an adhesive layer is provided adjacent to this vapor-deposited film, it is preferable that the adhesive layer be composed of a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound. When a laminate with a vapor-deposited film is used as a packaging material, a bending load is applied to the laminate by a molding machine or the like, which may cause cracks in the aluminum vapor-deposited film. By using the specific adhesive as described above, it is possible to suppress a decrease in the oxygen barrier property and water vapor barrier property even if cracks occur in the aluminum vapor-deposited film.

[0072] The polyester polyol has two or more hydroxyl groups as functional groups in one molecule. The isocyanate compound has two or more isocyanate groups as functional groups in one molecule. The polyester polyol has, for example, a polyester structure or a polyester polyurethane structure as the main skeleton.

[0073] As a specific example of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound, the PASLIM series sold by DIC Corporation can be used.

[0074] The resin composition may further contain a plate-like inorganic compound, a coupling agent, cyclodextrin and / or a derivative thereof, and the like.

[0075] As polyester polyols having two or more hydroxyl groups in one molecule as functional groups, for example, the following [Example 1] to [Example 3] can be used. [Example 1] Polyester polyol obtained by polycondensation of ortho-oriented polycarboxylic acid or its anhydride with polyhydric alcohol [Example 2] Polyester polyol with a glycerol skeleton [Example 3] Polyester polyol with isocyanuric ring Each polyester polyol will be described below.

[0076] The polyester polyol according to the first example is a polycondensate obtained by polycondensing a polycarboxylic acid component containing at least one or more of orthophthalic acid and its anhydride, and a polyhydric alcohol component containing at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol. In particular, polyester polyols in which the content of orthophthalic acid and its anhydride relative to the total polycarboxylic acid components is 70 to 100 mass % are preferred.

[0077] The polyester polyol according to the first example essentially contains orthophthalic acid and its anhydride as polycarboxylic acid components, but other polycarboxylic acid components may be copolymerized within a range that does not impair the effects of this embodiment. Specific examples include aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; unsaturated bond-containing polycarboxylic acids such as maleic anhydride, maleic acid, and fumaric acid; alicyclic polycarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, anhydrides of these dicarboxylic acids, and ester-forming derivatives of these dicarboxylic acids; and polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids. Among these, succinic acid, 1,3-cyclopentanedicarboxylic acid, and isophthalic acid are preferred. Two or more of the above other polycarboxylic acids may be used.

[0078] As a polyester polyol according to a second example, a polyester polyol having a glycerol skeleton represented by general formula (1) can be mentioned. [ka] In general formula (1), R1, R2, and R3 are each independently H (hydrogen atom) or a group represented by the following general formula (2). [ka]

[0079] In formula (2), n represents an integer of 1 to 5, X represents an arylene group selected from the group consisting of 1,2-phenylene groups, 1,2-naphthylene groups, 2,3-naphthylene groups, 2,3-anthraquinonediyl groups, and 2,3-anthracenediyl groups, which may have a substituent, and Y represents an alkylene group having 2 to 6 carbon atoms. However, at least one of R1, R2, and R3 represents a group represented by general formula (2).

[0080] In general formula (1), at least one of R1, R2, and R3 must be a group represented by general formula (2). In particular, it is preferable that all of R1, R2, and R3 are groups represented by general formula (2).

[0081] In addition, the compound may be a mixture of two or more of the following compounds: a compound in which any one of R1, R2, and R3 is a group represented by general formula (2); a compound in which any two of R1, R2, and R3 are groups represented by general formula (2); and a compound in which all of R1, R2, and R3 are groups represented by general formula (2).

[0082] X represents an optionally substituted arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group. When X is substituted with a substituent, it may be substituted with one or more substituents, and the substituent is bonded to any carbon atom on X that is different from the free radical. The substituent includes a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.

[0083] In general formula (2), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, a propylene group, a butylene group, a neopentylene group, a 1,5-pentylene group, a 3-methyl-1,5-pentylene group, a 1,6-hexylene group, a methylpentylene group, or a dimethylbutylene group. Of these, a propylene group or an ethylene group is preferred, and an ethylene group is most preferred.

[0084] The polyester resin compound having a glycerol skeleton represented by general formula (1) can be synthesized by reacting glycerol, an aromatic polycarboxylic acid or its anhydride in which a carboxylic acid is substituted at the ortho position, and a polyhydric alcohol component as essential components.

[0085] Examples of aromatic polycarboxylic acids or anhydrides in which a carboxylic acid is substituted at the ortho position include orthophthalic acid or anhydride, naphthalene 2,3-dicarboxylic acid or anhydride, naphthalene 1,2-dicarboxylic acid or anhydride, anthraquinone 2,3-dicarboxylic acid or anhydride, and 2,3-anthracenecarboxylic acid or anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring, such as a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, or a naphthyl group.

[0086] Examples of polyhydric alcohol components include alkylene diols having 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol.

[0087] The polyester polyol according to the third example is a polyester polyol having an isocyanuric ring represented by the following general formula (3). [ka] In the general formula (3), R1, R2, and R3 each independently represent "-(CH2) n1 -OH (where n1 represents an integer of 2 to 4)" or a structure of general formula (4). [ka]

[0088] In general formula (4), n2 represents an integer of 2 to 4, n3 represents an integer of 1 to 5, X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have a substituent, and Y represents an alkylene group having 2 to 6 carbon atoms. However, at least one of R1, R2, and R3 is a group represented by general formula (4).

[0089] In the general formula (3), -(CH2) n1 The alkylene group represented by - may be linear or branched. Among these, n1 is preferably 2 or 3, and most preferably 2.

[0090] In the general formula (4), n2 represents an integer of 2 to 4, and n3 represents an integer of 1 to 5. X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have a substituent.

[0091] When X is substituted with a substituent, it may be substituted with one or more substituents, and the substituent is bonded to any carbon atom on X that is different from the free radical. The substituent includes a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group. The substituent for X is preferably a hydroxyl group, a cyano group, a nitro group, an amino group, a phthalimido group, a carbamoyl group, an N-ethylcarbamoyl group, or a phenyl group, and most preferably a hydroxyl group, a phenoxy group, a cyano group, a nitro group, a phthalimido group, or a phenyl group.

[0092] In general formula (4), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, a propylene group, a butylene group, a neopentylene group, a 1,5-pentylene group, a 3-methyl-1,5-pentylene group, a 1,6-hexylene group, a methylpentylene group, or a dimethylbutylene group. Of these, a propylene group or an ethylene group is preferred, and an ethylene group is most preferred.

[0093] In general formula (3), at least one of R1, R2, and R3 is a group represented by general formula (4). In particular, it is preferable that all of R1, R2, and R3 are groups represented by general formula (4).

[0094] In addition, the compound may be a mixture of two or more of the following compounds: a compound in which any one of R1, R2, and R3 is a group represented by general formula (4); a compound in which any two of R1, R2, and R3 are groups represented by general formula (4); and a compound in which all of R1, R2, and R3 are groups represented by general formula (4).

[0095] The polyester polyol having an isocyanuric ring represented by general formula (3) can be synthesized by reacting a triol having an isocyanuric ring, an aromatic polycarboxylic acid or its anhydride in which a carboxylic acid is substituted at the ortho position, and a polyhydric alcohol component as essential components.

[0096] Examples of triols having an isocyanuric ring include alkylene oxide adducts of isocyanuric acid such as 1,3,5-tris(2-hydroxyethyl)isocyanuric acid and 1,3,5-tris(2-hydroxypropyl)isocyanuric acid.

[0097] Examples of aromatic polycarboxylic acids or anhydrides in which a carboxylic acid is substituted at the ortho position include orthophthalic acid or anhydride, naphthalene 2,3-dicarboxylic acid or anhydride, naphthalene 1,2-dicarboxylic acid or anhydride, anthraquinone 2,3-dicarboxylic acid or anhydride, and 2,3-anthracene carboxylic acid or anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring.

[0098] Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimido group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group.

[0099] The polyhydric alcohol component may be an alkylene diol having 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, or dimethylbutanediol. Among these, polyester polyol compounds having an isocyanuric ring, which use 1,3,5-tris(2-hydroxyethyl)isocyanuric acid or 1,3,5-tris(2-hydroxypropyl)isocyanuric acid as the triol compound having an isocyanuric ring, orthophthalic anhydride as the aromatic polycarboxylic acid or its anhydride in which the carboxylic acid is substituted at the ortho position, and ethylene glycol as the polyhydric alcohol, are particularly preferred because of their excellent oxygen barrier properties and adhesiveness.

[0100] The isocyanuric ring is highly polar and trifunctional, and can increase the polarity of the entire system and the crosslink density. From these perspectives, it is preferable that the adhesive resin contains 5% by mass or more of the isocyanuric ring based on the total solid content of the adhesive resin.

[0101] The isocyanate compound has two or more isocyanate groups in the molecule. The isocyanate compound may be either aromatic or aliphatic, and may be either a low molecular weight compound or a high molecular weight compound. Furthermore, the isocyanate compound may be a blocked isocyanate compound obtained by addition reaction using a known isocyanate blocking agent by a known, conventional appropriate method. Among these, from the viewpoints of adhesiveness and retort resistance, polyisocyanate compounds having three or more isocyanate groups are preferred, and from the viewpoints of oxygen barrier property and water vapor barrier property, aromatic compounds are preferred.

[0102] Specific examples of the isocyanate compound include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, metaxylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds, as well as adducts, biurets, and allophanates obtained by reacting these isocyanate compounds with low-molecular-weight active hydrogen compounds or alkylene oxide adducts thereof, or high-molecular-weight active hydrogen compounds. Examples of low molecular weight active hydrogen compounds include ethylene glycol, propylene glycol, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, and metaxylylenediamine. Examples of high molecular weight active hydrogen compounds include polymeric active hydrogen compounds of various polyester resins, polyether polyols, and polyamides.

[0103] The phosphoric acid-modified compound is, for example, a compound represented by the following general formula (5) or (6). [ka] In general formula (5), R1, R2, and R3 are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, a phenyl group which may have a substituent, and an alkyl group having 1 to 4 carbon atoms which has a (meth)acryloyloxy group, at least one of which is a hydrogen atom, and n is an integer of 1 to 4. [ka] In the formula, R4 and R5 are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, a phenyl group which may have a substituent, and an alkyl group having 1 to 4 carbon atoms and having a (meth)acryloyloxy group, n is an integer of 1 to 4, x is an integer of 0 to 30, and y is an integer of 0 to 30, except when both x and y are 0.

[0104] More specific examples include phosphoric acid, pyrophosphoric acid, triphosphoric acid, methyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, dibutyl phosphate, 2-ethylhexyl acid phosphate, bis(2-ethylhexyl) phosphate, isododecyl acid phosphate, butoxyethyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, and polyoxyethylene alkyl ether phosphate, and one or more of these can be used.

[0105] The content of the phosphoric acid-modified compound in the resin composition is preferably 0.005% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 1% by mass or less. By adjusting the content of the phosphate-modified compound to 0.005% by mass or more, the oxygen barrier property and water vapor barrier property of the laminate of the present invention can be improved, and by adjusting the content of the phosphate-modified compound to 10% by mass or less, the adhesiveness of the adhesive layer can be improved.

[0106] The resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound may contain a plate-like inorganic compound, which can improve the adhesiveness of the adhesive layer and the flex load resistance of the laminate of the present invention. Examples of the plate-like inorganic compounds include kaolinite-serpentine group clay minerals (halloysite, kaolinite, endelite, dickite, nacrite, antigorite, chrysotile, etc.) and pyrophyllite-talc group (pyrophyllite, talc, keroli, etc.).

[0107] Examples of coupling agents include silane-based coupling agents, titanium-based coupling agents, and aluminum-based coupling agents represented by the following general formula (7). These coupling agents may be used alone or in combination of two or more. [ka]

[0108] Examples of silane coupling agents include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxytrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β( N-beta(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-beta(aminoethyl)γ-aminopropyltrimethoxysilane, N-beta(aminoethyl)γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethylbutylidene).

[0109] Examples of titanium-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraoctyl bis(didodecyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, bis(dioctyl pyrophosphate)ethylene titanate, isopropyl trioctainol titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, diisostearoyl ethylene titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumyl phenyl titanate, and dicumyl phenyl oxyacetate titanate.

[0110] Specific examples of aluminum-based coupling agents include acetoalkoxyaluminum diisopropylate, diisopropoxyaluminum ethyl acetoacetate, diisopropoxyaluminum monomethacrylate, isopropoxyaluminum alkyl acetoacetate mono(dioctyl phosphate), aluminum-2-ethylhexanoate oxide trimer, aluminum stearate oxide trimer, and alkyl acetoacetate aluminum oxide trimer.

[0111] The resin composition may contain cyclodextrin and / or a derivative thereof, which can improve the adhesiveness of the adhesive layer and further improve the flex load resistance of the laminate of the present invention. Specifically, for example, cyclodextrin, alkylated cyclodextrin, acetylated cyclodextrin, hydroxyalkylated cyclodextrin, and the like, in which the hydrogen atoms of the hydroxyl groups of the glucose units of cyclodextrin are substituted with other functional groups, can be used. Branched cyclic dextrins can also be used. Furthermore, the cyclodextrin skeleton in cyclodextrin and cyclodextrin derivatives may be any of α-cyclodextrin consisting of six glucose units, β-cyclodextrin consisting of seven glucose units, and γ-cyclodextrin consisting of eight glucose units. These compounds may be used alone or in combination of two or more. These cyclodextrins and / or their derivatives may hereinafter be collectively referred to as dextrin compounds.

[0112] From the viewpoint of compatibility and dispersibility in the resin composition, it is preferable to use a cyclodextrin derivative as the cyclodextrin compound.

[0113] Examples of alkylated cyclodextrins include methyl-α-cyclodextrin, methyl-β-cyclodextrin, and methyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

[0114] Examples of acetylated cyclodextrins include monoacetyl-α-cyclodextrin, monoacetyl-β-cyclodextrin, and monoacetyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

[0115] Examples of hydroxyalkylated cyclodextrins include hydroxypropyl-α-cyclodextrin, hydroxypropyl-β-cyclodextrin, and hydroxypropyl-γ-cyclodextrin. These compounds may be used alone or in combination of two or more.

[0116] The thickness of the adhesive layer is preferably 0.5 μm or more and 6 μm or less, more preferably 0.8 μm or more and 5 μm or less, and even more preferably 1 μm or more and 4.5 μm or less. By making the thickness of the adhesive layer 0.5 μm or more, the adhesiveness of the adhesive layer can be improved. Furthermore, when an adhesive layer made of a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphoric acid-modified compound is provided adjacent to an aluminum vapor-deposited film, the bending load resistance of the laminate can be improved. By setting the thickness of the adhesive layer to 6 μm or less, the processability of the laminate can be improved.

[0117] Alternatively, the heat seal layer can be formed by extruding a resin material containing polyethylene onto a substrate or a polyethylene layer having a vapor-deposited film, and then drying the extruded resin material.

[0118] <Polyethylene layer with vapor deposition film> In one embodiment, the laminate according to the present invention comprises a polyethylene layer having a vapor-deposited film between the substrate and the heat seal layer, thereby improving the gas barrier properties of the laminate according to the present invention.

[0119] The polyethylene layer having the vapor-deposited film may be composed of a stretched film or an unstretched film, but is preferably a stretched film from the viewpoints of printability, strength, and heat resistance of the laminate. Also, it may be uniaxially stretched or biaxially stretched, but is preferably a biaxially stretched film from the viewpoint of strength.

[0120] The polyethylene layer having the vapor-deposited film contains biomass-derived polyethylene. Among biomass-derived polyethylenes, high-density polyethylene (HDPE) and medium-density polyethylene (MDPE) are preferred from the viewpoints of printability, strength, and heat resistance, and medium-density polyethylene is more preferred from the viewpoint of suitability for stretching.

[0121] The content of biomass-derived polyethylene in the polyethylene layer comprising the vapor-deposited film is preferably 50% by mass or more and 80% by mass or less, and more preferably 55% by mass or more and 70% by mass or less, which allows for a high biomass content, further reducing the environmental load, and preventing bleed-out onto the film surface.

[0122] The polyethylene layer comprising the vapor-deposited film may contain polyethylene derived from a source other than biomass, provided that the properties of the present invention are not impaired. It may also contain additives, such as crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

[0123] From the viewpoint of productivity and economy, the thickness of the polyethylene layer having the vapor-deposited film is preferably 9 μm or more and 50 μm or less, and more preferably 12 μm or more and 30 μm or less. The thickness of the vapor-deposited film is preferably 0.002 μm or more and 0.4 μm or less, and more preferably 0.005 μm or more and 0.1 μm or less. By keeping the thickness of the vapor-deposited film within the above numerical range, it is possible to prevent cracks and the like from occurring in the vapor-deposited film while maintaining gas barrier properties.

[0124] The polyethylene layer having the vapor-deposited film may have an image formed on its surface by the image forming method described above.

[0125] The polyethylene layer having a vapor-deposited film can be formed by producing a polyethylene film by melt extrusion molding such as inflation molding or T-die molding from a resin material containing polyethylene, forming a vapor-deposited film on at least one surface of the polyethylene film by the above-mentioned method, and then laminating the film on a substrate via an adhesive. In this case, the polyethylene film may be subjected to a stretching treatment before vapor deposition or lamination. Alternatively, a polyethylene layer having a vapor-deposited film can be formed by extruding a resin material containing polyethylene onto a substrate, drying it, and then forming a vapor-deposited film.

[0126] <Packaging materials> In one embodiment, the packaging material according to the present invention can be produced by folding the laminate in half, overlapping it so that the heat seal layer of the laminate is on the inside, and heat sealing the edges. Alternatively, the laminate can be produced by overlapping two laminates with their heat seal layers facing each other and heat sealing the edges. Depending on the sealing method, various types of packaging materials can be produced by heat sealing using heat sealing forms such as side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, palm seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, gusset type, and others. Other examples include self-standing packaging bags (standing pouches), etc. Heat sealing can be performed by known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

[0127] The laminate of the present invention, even if it is made of only one type of resin (i.e., polyethylene), has a base material that satisfies the strength and printability required for an outer film of a packaging material, and the heat seal layer enables packaging, making it extremely suitable as a material for constituting packaging materials that require recyclability. [Example]

[0128] The present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

[0129] Example 1 Biomass-derived linear low-density polyethylene (density: 0.916 g / cm 3The polyethylene film (MFR: 1.3 g / 10 min, biomass content: 87%, manufactured by Braskem, trade name: SLL118) was formed into films by inflation molding to obtain polyethylene films with thicknesses of 100 μm and 40 μm. A polyethylene film having a thickness of 100 μm was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a substrate having a thickness of 20 μm.

[0130] After stretching, the substrate and the polyethylene film were laminated together with a two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., trade name: RU-77T / H-7) interposed therebetween to obtain a laminate.

[0131] <Example 2> Biomass-derived linear low-density polyethylene (density: 0.916 g / cm3, MFR: 1.3 g / 10 min, biomass content: 87%, manufactured by Braskem, product name: SLL118) was formed into films by inflation molding to obtain polyethylene films with thicknesses of 100 μm and 40 μm. A polyethylene film having a thickness of 100 μm was stretched in the machine direction (MD) at a stretching ratio of 2.24 times and in the transverse direction (TD) at a stretching ratio of 2.24 times to obtain a substrate having a thickness of 20 μm.

[0132] After stretching, the substrate and the polyethylene film were laminated together with a two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., trade name: RU-77T / H-7) interposed therebetween to obtain a laminate.

[0133] <Comparative Example 1> Biomass-derived linear low-density polyethylene (density: 0.916 g / cm 3 A polyethylene film having a thickness of 20 μm and 40 μm was formed from a polyethylene terephthalate (MFR: 1.3 g / 10 min, biomass content: 87%, manufactured by Braskem, trade name: SLL118) by inflation molding.

[0134] Two polyethylene films were laminated together with a two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., trade name: RU-77T / H-7) interposed therebetween to obtain a laminate.

[0135] <Printability evaluation> An image was formed on one side of the substrate and polyethylene film prepared in the above Examples and Comparative Examples by flexographic printing using a water-based flexographic ink (manufactured by Toyo Ink Co., Ltd., trade name: Aquariona). The formed image was visually observed, and the printability of the substrate and polyethylene film was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1. (Evaluation criteria) ◯: The dimensional stability during printing was good, and a good image was formed without rubbing, bleeding, or the like. ×: The film expanded and contracted during printing, causing rubbing and bleeding in the formed image.

[0136] <Rigidity evaluation> The substrates and polyethylene films prepared in the above Examples and Comparative Examples were cut into 15 mm wide test pieces, and their stiffness was measured using a loop stiffness tester (manufactured by Toyo Seiki Seisakusho, product name: Loop Stiffness Tester). The loop length was 60 mm. The measurement results are summarized in Table 1.

[0137] <Strength evaluation> The substrates and polyethylene films prepared in the above Examples and Comparative Examples were cut into 10 mm wide dumbbell-shaped test pieces. The tensile strength of these test pieces in the MD direction was measured using a tensile tester (Orientec Co., Ltd., RTC-1310A). The chuck distance was 10 mm, and the pulling speed was 300 mm / min. The measurement results are summarized in Table 1.

[0138] [Table 1] [Explanation of symbols]

[0139] 10: Laminate 20: Base material 30: Heat seal layer 40: Polyethylene layer with vapor deposition film

Claims

1. The film includes at least a substrate and a heat seal layer, the substrate is made of polyethylene, the heat seal layer is made of polyethylene, The substrate has been subjected to a stretching treatment, The heat seal layer is unstretched, the substrate includes at least a layer containing high-density polyethylene and a layer containing medium-density polyethylene; A laminate, wherein the substrate and the heat seal layer contain polyethylene derived from biomass.

2. The laminate according to claim 1 , wherein the content of the biomass-derived polyethylene in the substrate and the heat seal layer is 50% by mass or more and 80% by mass or less.

3. The laminate according to claim 1 or 2, wherein the stretching ratio in the machine direction (MD) of the substrate is 2 times or more and 10 times or less.

4. The laminate according to any one of claims 1 to 3, wherein the substrate has a thickness of 9 µm or more and 50 µm or less.

5. The laminate according to any one of claims 1 to 4, wherein an image is formed on at least one surface of the substrate.

6. The laminate according to any one of claims 1 to 5, wherein the substrate is produced by an inflation molding method.

7. The laminate of any one of claims 1 to 6, wherein the heat seal layer comprises at least one of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

8. A packaging material comprising the laminate according to any one of claims 1 to 7.

Images