Polyethylene laminate for packaging material and packaging material comprising the same

Abstract

To provide a polyethylene laminate for a packaging material having high recycling properties, printability and strength.SOLUTION: The polyethylene laminate for the packaging material includes at least a stretched polyethylene film and a heat-sealable polyethylene layer, and an image is formed on at least one surface of the stretched polyethylene film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polyethylene laminate for use as a packaging material and a packaging material comprising said 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 polyethylene laminate for packaging materials that has high recyclability, printability and strength. [Means for solving the problem]

[0007] The polyethylene laminate for packaging material of the present invention is characterized by comprising at least a stretched polyethylene film and a heat-sealable polyethylene layer, with an image formed on at least one surface of the stretched polyethylene film.

[0008] In one embodiment, the oriented polyethylene film comprises at least one of high density polyethylene (HDPE) and medium density polyethylene (MDPE).

[0009] In one embodiment, the stretched polyethylene film is stretched at a stretch ratio in the machine direction (MD) of 2 times or more and 10 times or less.

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

[0011] In one embodiment, the stretched polyethylene film has a configuration consisting of a high density polyethylene layer / a medium density polyethylene layer / a high density polyethylene layer.

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

[0013] In one embodiment, the image is formed on the heat-sealable polyethylene layer side of the stretched polyethylene film, and the haze value of the stretched polyethylene film is 20% or less.

[0014] In one embodiment, the heat-sealable polyethylene layer comprises at least one of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE).

[0015] The packaging material of the present invention is characterized by being composed of the above laminate. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a polyethylene laminate for packaging materials that has high recyclability, printability and strength. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional schematic view showing one embodiment of a polyethylene laminate for packaging materials according to the present invention. [Figure 2] 1 is a cross-sectional schematic view showing one embodiment of a polyethylene laminate for packaging materials according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] <Polyethylene laminate for packaging materials> The polyethylene laminate for packaging material according to the present invention will be described with reference to the drawings. As shown in FIG. 1, the polyethylene laminate for packaging materials 10 comprises at least a stretched polyethylene film 20 and a heat-sealable polyethylene layer 30 . In one embodiment, a polyethylene layer 40 comprising a vapor-deposited film is provided between the stretched polyethylene film 20 and the heat-sealable polyethylene layer 30 . Each layer of the polyethylene laminate for packaging materials will be described below.

[0019] <Stretched polyethylene film> The stretched polyethylene film may be uniaxially stretched or biaxially stretched, but from the viewpoint of strength, biaxially stretched films are preferred.

[0020] The stretching ratio in the machine direction (MD) of the stretched polyethylene film is preferably 2 to 10 times, and more preferably 3 to 7 times. This can further improve the printability and strength of the polyethylene laminate. It can also improve the transparency of the stretched polyethylene film. The stretching ratio in the transverse direction (TD) is preferably 2 to 10 times, and more preferably 3 to 7 times, which can further improve the printability and strength of the polyethylene laminate and can also improve the transparency of the stretched polyethylene film.

[0021] Examples of polyethylene contained in the oriented polyethylene film include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). The oriented polyethylene film 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 polyethylene 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 0.925g / cm 3 It refers to something less than.

[0022] The polyethylenes having different densities and branches 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 a 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.

[0023] 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.

[0024] 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.

[0025] 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 cyclopentadienyl skeleton ligands 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.

[0026] 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.

[0027] 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.

[0028] Copolymers of ethylene and other monomers can also be used as long as the properties of the present invention are not impaired. Examples of ethylene copolymers include copolymers of ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms 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. Copolymers with vinyl acetate, acrylic esters, and the like can also be used as long as the objects of the present invention are not impaired.

[0029] Furthermore, in the present invention, biomass-derived ethylene may be used as a raw material for obtaining the high-density polyethylene, etc., instead of ethylene obtained from fossil fuels. Such biomass-derived polyethylene is a carbon-neutral material, and therefore can be used as a packaging material with even less environmental impact. Such biomass-derived polyethylene can be produced, for example, by a method such as that described in JP 2013-177531 A. Alternatively, commercially available biomass-derived polyethylene (e.g., Green PE commercially available from Braskem) may be used.

[0030] The polyethylene content in the stretched polyethylene film is preferably 50% by mass or more, and more preferably 70% by mass or more.

[0031] The stretched polyethylene film may contain additives within the range that does not impair the properties of the present invention, such as crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, etc.

[0032] In one embodiment, the oriented polyethylene film has a multi-layer structure, preferably comprising a layer comprising high density polyethylene (HDPE) and a layer comprising medium density polyethylene (MDPE). For example, it has a structure of high-density polyethylene layer / medium-density polyethylene layer / high-density polyethylene layer. This structure can further improve the printability and strength of the polyethylene laminate. In this case, the ratio of the thickness of the high-density polyethylene layer to 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.

[0033] The thickness of the stretched polyethylene film 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 stretched polyethylene film within the above numerical range, the printability, strength, and heat resistance of the polyethylene laminate can be further improved.

[0034] The stretched polyethylene film has an image such as a letter, a pattern, a symbol, etc. formed on at least one surface thereof. In order to prevent deterioration of the image over time, it is preferable that the image be formed on the side of the stretched polyethylene film where the heat-sealable polyethylene layer is laminated. 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.

[0035] When an image is formed on the side of the stretched polyethylene film where the heat-sealable polyethylene layer is laminated, the haze value of the stretched polyethylene film is preferably 20% or less, more preferably 10% or less. This improves the visibility of the formed image. The haze value of the stretched polyethylene film can be adjusted by changing the stretching ratio, etc. In the present invention, the haze value can be measured in accordance with JIS K-7105.

[0036] In one embodiment, the stretched polyethylene film 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 polyethylene 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.

[0037] 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.

[0038] Also, for example, a composite film consisting of two or more layers of vapor-deposited films of different inorganic oxides can be formed and used by combining physical vapor deposition and chemical vapor deposition. The degree of vacuum in the deposition chamber is 10 -2 ~10 -8 mbar, especially 10 -3 ~10 -7 After oxygen is introduced, the pressure is preferably about 10 -1 ~10 -6 mbar, especially 10 -2 ~10 -5 A pressure of about mbar is preferred. The amount of oxygen introduced varies depending on the size of the deposition machine. An inert gas such as argon gas, helium gas, or nitrogen gas may be used as a carrier gas for the oxygen introduced, provided that this does not cause any problems. The film transport speed is preferably about 10 to 800 m / min, and particularly about 50 to 600 m / min.

[0039] A stretched polyethylene film can be obtained by melting a resin material containing polyethylene, forming the melt into a film by a melt extrusion molding method such as inflation molding or T-die molding, and then stretching the film. The inflation molding method is preferred because it allows for easier stretching. A stretched polyethylene film having a multilayer structure can be produced by melt co-extruding multiple resin materials.

[0040] 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.

[0041] <Heat-sealable polyethylene layer> The heat-sealable polyethylene layer contains at least one of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and copolymers of ethylene and other monomers. Among these, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) are preferred from the viewpoint of heat-sealability. From the viewpoint of environmental impact, these polyethylenes are preferably derived from biomass.

[0042] The content of polyethylene in the heat-sealable polyethylene layer is preferably 50% by mass or more, and more preferably 70% by mass or more.

[0043] The heat-sealable polyethylene layer may contain additives within the range that does not impair the properties of the present invention, such as crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, etc.

[0044] The thickness of the heat-sealable polyethylene 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-sealable polyethylene layer within the above numerical range, the heat-sealability can be improved.

[0045] The heat-sealable polyethylene 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 comprising a stretched polyethylene film or a vapor-deposited film via an adhesive. The adhesive may be either a solvent-free adhesive or a solvent-based adhesive, but from the viewpoint of environmental load, a solvent-free adhesive is preferred. Examples of adhesives include polyvinyl acetate adhesives, polyacrylic ester adhesives, cyanoacrylate adhesives, ethylene copolymer adhesives, cellulose adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, amino resin adhesives, phenol resin adhesives, epoxy adhesives, urethane adhesives, rubber adhesives, and silicone adhesives.

[0046] Alternatively, a heat-sealable polyethylene layer can be formed by extruding a resin material containing polyethylene onto a polyethylene layer comprising a stretched polyethylene film or a vapor-deposited film, and then drying the extrusion.

[0047] <Polyethylene layer with vapor deposition film> In one embodiment, the polyethylene laminate according to the present invention comprises a polyethylene layer comprising a vapor-deposited film between the stretched polyethylene film and the heat-sealable polyethylene layer, thereby improving the gas barrier properties of the polyethylene laminate according to the present invention.

[0048] 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 polyethylene laminate. Also, it may be uniaxially stretched or biaxially stretched, but is preferably a biaxially stretched film from the viewpoint of strength.

[0049] The polyethylene layer comprising the vapor-deposited film contains at least one of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and copolymers of ethylene and other monomers. Among these, from the viewpoints of printability, strength, and heat resistance, high-density polyethylene (HDPE) and medium-density polyethylene (MDPE) are preferred, and high-density polyethylene (HDPE) is more preferred. From the viewpoint of environmental impact, these polyethylenes are preferably derived from biomass.

[0050] The polyethylene content in the polyethylene layer comprising the vapor-deposited film is preferably 50% by mass or more, and more preferably 70% by mass or more.

[0051] The polyethylene layer comprising the vapor-deposited film may contain additives within the range that does not impair the properties of the present invention, such as crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, etc.

[0052] 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.

[0053] The polyethylene layer having the vapor-deposited film may have an image formed on its surface by the image forming method described above.

[0054] 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 stretched polyethylene film via an adhesive. In this case, the polyethylene film may be subjected to a stretching treatment before vapor deposition or before lamination. Alternatively, a polyethylene layer having a vapor-deposited film can be formed by extruding a resin material containing polyethylene onto a stretched polyethylene film, drying the extruded resin material, and then forming a vapor-deposited film.

[0055] <Packaging materials> In one embodiment, the packaging material according to the present invention can be produced by folding the polyethylene laminate in half, overlapping it so that the heat-sealable polyethylene layer is on the inside, and heat-sealing the edges. Alternatively, it can be produced by overlapping two polyethylene laminates with the heat-sealable polyethylene 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.

[0056] Although the polyethylene laminate of the present invention is a laminate made of only one type of resin (i.e., polyethylene), the oriented polyethylene film satisfies the strength and printability required for an outer film of a packaging material, and the heat-sealable polyethylene layer enables packaging, making it extremely suitable as a material for constituting packaging materials that require recyclability. [Example]

[0057] The present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

[0058] Example 1 Medium density polyethylene (density: 0.941 g / cm 3 A polyethylene film having a thickness of 100 μm was formed from a polyethylene glycol terephthalate (e.g., melting point 129° C., MFR: 1.3 g / 10 min, manufactured by Dow Chemical Co., trade name: Elite 5538G) by inflation molding. This polyethylene film was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a stretched polyethylene film with a thickness of 20 μm. The haze value of the stretched polyethylene film was measured in accordance with JIS K-7105 and was found to be 6.5%.

[0059] The above stretched polyethylene film and a 40 μm thick unstretched linear low-density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., product name: L6100) were laminated together with a two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-77T / H-7) to obtain a polyethylene laminate.

[0060] <Example 2> High density polyethylene (density: 0.961 g / cm 3 , melting point 135°C, MFR: 0.7g / 10min, ExxonMobil, trade name: HTA108) and medium density polyethylene (density: 0.941g / cm 3A polyethylene film consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer was produced by inflation molding using a polyethylene terephthalate (Elite 5538G, melting point 129°C, MFR: 1.3 g / 10 min, manufactured by Dow Chemical). The high-density polyethylene layers were each 20 μm thick, and the medium-density polyethylene layer was 60 μm thick. This polyethylene film was stretched in the machine direction (MD) at a stretching ratio of 5 times to obtain a stretched polyethylene film with a thickness of 20 μm. The haze value of the stretched polyethylene film was 8.9%.

[0061] The above stretched polyethylene film and a 40 μm thick unstretched linear low-density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., product name: L6100) were laminated together with a two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-77T / H-7) to obtain a polyethylene laminate.

[0062] Example 3 Medium density polyethylene (density: 0.941 g / cm 3 A polyethylene film having a thickness of 100 μm was formed from a polyethylene glycol terephthalate (e.g., melting point 129° C., MFR: 1.3 g / 10 min, manufactured by Dow Chemical Co., trade name: Elite 5538G) by inflation molding. This polyethylene film was stretched in the machine direction (MD) and the transverse direction (TD) at a stretching ratio of 2.24 to obtain a stretched polyethylene film with a thickness of 20 μm. The haze value of the stretched polyethylene film was measured in accordance with JIS K-7105 and was found to be 5.1%. The above stretched polyethylene film and a 40 μm thick unstretched linear low-density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., product name: L6100) were laminated together with a two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-77T / H-7) to obtain a polyethylene laminate.

[0063] <Comparative Example 1> Medium density polyethylene (density: 0.941 g / cm 3A polyethylene film having a thickness of 20 μm was formed from a polyethylene terephthalate (Elite 5538G, melting point 129°C, MFR 1.3 g / 10 min, manufactured by Dow Chemical Co.) by inflation molding. The haze value of the polyethylene film was measured in accordance with JIS K-7105 and was found to be 23.5%.

[0064] The polyethylene film was laminated with a 40 μm-thick unstretched linear low-density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., product name: L6100) via a two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-77T / H-7) to obtain a polyethylene laminate.

[0065] <Comparative Example 2> High density polyethylene (density: 0.961 g / cm 3 A polyethylene film consisting of a high-density polyethylene layer / medium-density polyethylene layer / high-density polyethylene layer was produced by inflation molding using a polyethylene polyethylene (density: 0.941 g / cm3, melting point: 135°C, MFR: 0.7 g / 10 min, ExxonMobil, trade name: HTA108) and a medium-density polyethylene (density: 0.941 g / cm3, melting point: 129°C, MFR: 1.3 g / 10 min, Dow Chemical, trade name: Elite5538G). The high-density polyethylene layer was 4 μm thick, and the medium-density polyethylene layer was 12 μm thick. The haze value of the polyethylene film was measured in accordance with JIS K-7105 and was found to be 28.8%.

[0066] The polyethylene film was laminated with a 40 μm-thick unstretched linear low-density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., product name: L6100) via a two-component curing urethane adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-77T / H-7) to obtain a polyethylene laminate.

[0067] <Printability evaluation> An image was formed on one side of the stretched polyethylene film and polyethylene film produced 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 stretched polyethylene film 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.

[0068] <Rigidity evaluation> The stretched polyethylene films and polyethylene films produced 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.

[0069] <Strength evaluation> The stretched polyethylene films 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.

[0070] [Table 1] [Explanation of symbols]

[0071] 10: Polyethylene laminate for packaging materials 20: Stretched polyethylene film 30: Heat-sealable polyethylene layer 40: Polyethylene layer with vapor deposition film

Claims

1. The film comprises at least a stretched polyethylene film and a heat-sealable polyethylene layer, A polyethylene laminate for packaging material, characterized in that an image is formed on at least one surface of the stretched polyethylene film.

2. 2. The polyethylene laminate for packaging materials according to claim 1, wherein the oriented polyethylene film comprises at least one of high density polyethylene (HDPE) and medium density polyethylene (MDPE).

3. 3. The polyethylene laminate for packaging materials according to claim 1, wherein the stretched polyethylene film has a stretching ratio in the machine direction (MD) of 2 times or more and 10 times or less.

4. The polyethylene laminate for packaging materials according to any one of claims 1 to 3, wherein the thickness of the stretched polyethylene film is 9 µm or more and 50 µm or less.

5. The polyethylene laminate for packaging materials according to any one of claims 1 to 4, wherein the stretched polyethylene film has a configuration consisting of a high-density polyethylene layer / a medium-density polyethylene layer / a high-density polyethylene layer.

6. 6. The polyethylene laminate for packaging materials according to claim 1, wherein the stretched polyethylene film is produced by inflation molding.

7. the image is formed on the heat-sealable polyethylene layer side of the stretched polyethylene film, The polyethylene laminate for packaging materials according to any one of claims 1 to 6, wherein the haze value of the stretched polyethylene film is 20% or less.

8. 8. The polyethylene laminate for packaging materials according to claim 1, wherein the heat-sealable polyethylene layer comprises at least one of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE).

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

Images