JP2023062051A - Polyethylene laminate for packaging material and packaging material composed of laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyethylene laminate for packaging material having high recycling suitability, printability and strength.

SOLUTION: A polyethylene laminate for packaging material at least contains a stretched polyethylene film, and a heat-sealable polyethylene layer. On at least one side of the stretched polyethylene film, an image is formed.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a polyethylene laminate for packaging materials and a packaging material comprising the laminate.

BACKGROUND ART Polyethylene films have appropriate flexibility, are excellent in transparency, moisture resistance, chemical resistance, etc., and are inexpensive, and are therefore used for various packaging materials. In particular, since the melting point of polyethylene is generally about 100 to 140° C., although it varies somewhat depending on the type, it is generally used as a heat-sealable film in the field of packaging materials.

On the other hand, polyethylene films are inferior in rigidity to other thermoplastic resin films, and thus have poor printability and cannot form clear images on their surfaces. In addition, the polyethylene film does not have high strength and cannot satisfy the durability required as the exterior of the packaging material. Therefore, a laminate is formed by laminating a resin film with excellent rigidity and strength such as a polyester film or nylon film and a polyethylene film, and the edges of the laminate are heat-sealed so that the polyethylene film side of this laminate is on the inside. A packaging material is manufactured by doing so (for example, Japanese Unexamined Patent Application Publication No. 2005-104525).

By the way, in recent years, along with the increasing demand for building a recycling-oriented society, attempts have been made to recycle and use packaging materials. However, when different types of resin films are laminated together as described above, it is difficult to separate the resin films from each other, and thus the resin films are not suitable for recycling.

JP-A-2005-104525

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a polyethylene laminate for packaging materials having high recyclability, printability and strength. .

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

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

In one embodiment, the draw ratio of the stretched polyethylene film in the machine direction (MD) is 2 times or more and 10 times or less.

In one embodiment, the stretched polyethylene film has a thickness of 9 μm or more and 50 μm or less.

In one embodiment, the oriented polyethylene film has a configuration of high density polyethylene layer/medium density polyethylene layer/high density polyethylene layer.

In one embodiment, the oriented polyethylene film is produced by a blown film method.

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.

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

A packaging material of the present invention is characterized by comprising the laminate described above.

ADVANTAGE OF THE INVENTION According to this invention, the polyethylene laminated body for packaging materials which has high recyclability, printability, and strength can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic which shows one Embodiment of the polyethylene laminated body for packaging materials by this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic which shows one Embodiment of the polyethylene laminated body for packaging materials by this invention.

<Polyethylene laminate for packaging materials>
A polyethylene laminate for packaging material according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, a polyethylene laminate 10 for packaging materials includes at least a stretched polyethylene film 20 and a heat-sealable polyethylene layer 30. As shown in FIG.
Also, in one embodiment, a polyethylene layer 40 comprising a deposited film is provided between the oriented polyethylene film 20 and the heat-sealable polyethylene layer 30 .
Each layer included in the polyethylene laminate for packaging materials will be described below.

<Stretched polyethylene film>
The stretched polyethylene film may be uniaxially stretched or biaxially stretched, but from the viewpoint of strength, biaxially stretched is preferred.

The stretching ratio in the longitudinal direction (MD) of the stretched polyethylene film is preferably 2 times or more and 10 times or less, and preferably 3 times or more and 7 times or less. This can further improve the printability and strength of the polyethylene laminate. Moreover, this can improve the transparency of the stretched polyethylene film.
The draw ratio in the transverse direction (TD) is preferably 2 times or more and 10 times or less, and preferably 3 times or more and 7 times or less. Thereby, the printability and strength of the polyethylene laminate can be further improved, and the transparency of the stretched polyethylene film can be improved.

The polyethylene contained in the oriented polyethylene film includes high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). Moreover, the stretched polyethylene film can contain two or more of these.
Among these, high-density polyethylene (HDPE) and medium-density polyethylene (MDPE) are preferable from the viewpoint of printability, strength and heat resistance of the polyethylene laminate, and medium-density polyethylene is more preferable from the viewpoint of stretching suitability.
In the present invention, high-density polyethylene has a density of 0.945 g/cm ³ or more, medium-density polyethylene has a density of 0.925 to 0.944 g/cm ³ , and low-density polyethylene has a density of 0. Less than .925 g/cm ³ .

Polyethylenes having different densities and branches as described above can be obtained by appropriately selecting a polymerization method. For example, using a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as a polymerization catalyst, by any method of gas phase polymerization, slurry polymerization, solution polymerization, and high pressure ion polymerization, It is preferable to carry out in one stage or in multiple stages of two or more stages.

The above-mentioned single-site catalyst is a catalyst capable of forming uniform active species, and is usually prepared by contacting a metallocene-based transition metal compound or a non-metallocene-based transition metal compound with an activating cocatalyst. . A single-site catalyst has a more uniform active site structure than a multi-site catalyst, and is therefore preferable because it can polymerize a polymer having a high molecular weight and a highly uniform structure. As the single-site catalyst, it is particularly preferable to use a metallocene-based catalyst. The metallocene catalyst is a catalyst containing a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a cocatalyst, an organometallic compound if necessary, and each catalyst component of a carrier. be.

In the 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. . Substituted cyclopentadienyl groups include hydrocarbon groups having 1 to 30 carbon atoms, silyl groups, silyl-substituted alkyl groups, silyl-substituted aryl groups, cyano groups, cyanoalkyl groups, cyanoaryl groups, halogen groups, haloalkyl groups and halosilyl groups. It has at least one substituent selected from groups and the like. The substituted cyclopentadienyl group may have two or more substituents, and the substituents are bonded to each other to form a ring such as an indenyl ring, a fluorenyl ring, an azulenyl ring, hydrogenated forms thereof, and the like. may be formed. A ring formed by combining substituents with each other may further have a substituent with each other.

In the transition metal compound of group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, examples of the transition metal include zirconium, titanium, hafnium and the like, with zirconium and hafnium being particularly preferred. The transition metal compound usually has two ligands having a cyclopentadienyl skeleton, and each ligand having a cyclopentadienyl skeleton is preferably bonded to each other by a bridging group. The bridging group includes an alkylene group having 1 to 4 carbon atoms, a silylene group, a dialkylsilylene group, a substituted silylene group such as a diarylsilylene group, and a substituted germylene group such as a dialkylgermylene group and a diarylgermylene group. A substituted silylene group is preferred. One or a mixture of two or more of the transition metal compounds of Group IV of the periodic table containing the ligand having a cyclopentadienyl skeleton can be used as a catalyst component.

The co-catalyst is one that can make the above Group IV transition metal compound of the periodic table effective as a polymerization catalyst, or one that can balance the ionic charges in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes of organoaluminumoxy compounds, benzene-insoluble organoaluminumoxy compounds, ion-exchange layered silicates, boron compounds, cations containing or not containing active hydrogen groups, and non-coordinating anions. ionic compounds, lanthanide salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing a fluoro group.

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 compound carrier before use. As the carrier, porous oxides of inorganic or organic compounds are preferable, and specifically, ion-exchange layered silicates such as montmorillonite, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ and B ₂ O. ₃ , CaO, ZnO, BaO, _ThO2 , etc. or mixtures thereof. Examples of organometallic compounds that may be used if necessary include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these, organic aluminum is preferably used.

Copolymers of ethylene and other monomers can also be used as long as the properties of the present invention are not impaired. Ethylene copolymers include copolymers composed of ethylene and α-olefins having 3 to 20 carbon atoms, and 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, 6-methyl- 1-heptene and the like can be mentioned. Moreover, it may be a copolymer with vinyl acetate, acrylic acid ester, or the like, as long as it does not impair the object of the present invention.

Further, in the present invention, biomass-derived ethylene may be used instead of ethylene obtained from fossil fuels as a raw material for obtaining the high-density polyethylene or the like. Since such biomass-derived polyethylene is a carbon-neutral material, it can be used as a packaging material with even less environmental impact. Such biomass-derived polyethylene can be produced, for example, by a method as described in JP-A-2013-177531. Also, commercially available biomass-derived polyethylene (eg, Green PE, commercially available from Braskem, etc.) may be used.

The content of polyethylene in the stretched polyethylene film is preferably 50% by mass or more, more preferably 70% by mass or more.

The stretched polyethylene film may contain additives within a range that does not impair the characteristics of the present invention, such as cross-linking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, Examples include pigments and modifying resins.

In one embodiment, the oriented polyethylene film has a multilayer structure. Preferably, it comprises a layer comprising high density polyethylene (HDPE) and a layer comprising medium density polyethylene (MDPE).
For example, it has a configuration consisting of a high-density polyethylene layer/medium-density polyethylene layer/high-density polyethylene layer. With such a configuration, the printability and strength of the polyethylene laminate can be further improved. At this time, the thickness ratio between the high-density polyethylene layer and the medium-density polyethylene layer is preferably 1/10 or more and 1/1 or less, more preferably 1/5 or more and 1/2 or less. preferable.

The thickness of the stretched polyethylene film is preferably 9 μm or more and 50 μm or less, 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.

The oriented polyethylene film has images such as characters, patterns, and symbols formed on at least one surface thereof. It is preferable that the image is formed on the side of the stretched polyethylene film on which the heat-sealable polyethylene layer is to be laminated, since this can prevent deterioration of the image over time.
The image forming method is not particularly limited, and conventionally known printing methods such as gravure printing, offset printing, and flexographic printing can be used. Among these, the flexographic printing method is preferable from the viewpoint of environmental load.

When an image is formed on the side of the stretched polyethylene film on which 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. The visibility of the image formed by this can be improved. The haze value of the stretched polyethylene film can be adjusted by changing the stretch ratio. Incidentally, in the present invention, the haze value can be measured according to JIS K-7105.

In one embodiment, the stretched polyethylene film has 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, and barium oxide on one surface. a deposited film containing a substance. Thereby, the gas barrier properties of the polyethylene laminate according to the present invention can be improved.
As a vapor deposition method, a conventionally known method can be employed, for example, a physical vapor deposition method (physical vapor deposition method, PVD method) such as a vacuum deposition method, a sputtering method, an ion plating method, or a plasma chemical vapor deposition method. , a thermal chemical vapor deposition method, a chemical vapor deposition method (Chemical Vapor Deposition method, CVD method) such as a photochemical vapor deposition method, and the like.

Moreover, the film thickness of the 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 setting the thickness of the vapor deposition film within the above numerical range, it is possible to prevent cracks and the like from occurring in the vapor deposition film while maintaining gas barrier properties.

Further, for example, both physical vapor deposition and chemical vapor deposition may be used in combination to form a composite film composed of two or more layers of deposited films of different inorganic oxides. The degree of vacuum in the deposition chamber is preferably about 10-2 to 10-8 mbar, particularly preferably about 10-3 to 10-7 mbar, before introducing oxygen, and about 10-1 to 10-6 mbar after introducing oxygen. , particularly about 10-2 to 10-5 mbar. The amount of oxygen to be introduced and the like differ depending on the size of the vapor deposition machine and the like. As the oxygen to be introduced, an inert gas such as argon gas, helium gas, nitrogen gas, or the like may be used as a carrier gas as long as there is no problem. The transport speed of the film is preferably about 10 to 800 m/min, more preferably about 50 to 600 m/min.

A stretched polyethylene film can be obtained by melting a resin material containing polyethylene, forming a film by a melt extrusion molding method such as an inflation molding method or a T-die molding method, and then stretching the film. The film is preferably produced by the inflation molding method because the stretching process can be performed more easily. A stretched polyethylene film having a multilayer structure can be produced by melt-coextrusion of a plurality of resin materials.

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

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

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

The heat-sealable polyethylene layer may contain additives as long as they do not impair the properties of the present invention. agents, pigments, modifying resins, and the like.

The thickness of the heat-sealable polyethylene layer is preferably 20 µm or more and 200 µm or less, 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.

The heat-sealable polyethylene layer is produced by forming a polyethylene film from a resin material containing polyethylene by a melt extrusion molding method such as inflation molding or T-die molding, and then applying an adhesive to the stretched polyethylene film. Alternatively, it can be formed by lamination on a polyethylene layer provided with a vapor-deposited film.
The adhesive may be a non-solvent type adhesive or a solvent type adhesive, but a non-solvent type adhesive is preferable from the viewpoint of environmental load.
Examples of adhesives include polyvinyl acetate adhesives, polyacrylate adhesives, cyanoacrylate adhesives, ethylene copolymer adhesives, cellulose adhesives, polyester adhesives, polyamide adhesives, Examples include polyimide adhesives, amino resin adhesives, phenol resin adhesives, epoxy adhesives, urethane adhesives, rubber adhesives, silicone adhesives, and the like.

A heat-sealable polyethylene layer can also be formed by extruding a resin material containing polyethylene onto a stretched polyethylene film or a polyethylene layer provided with a vapor-deposited film, followed by drying.

<Polyethylene layer with deposited film>
In one embodiment, the polyethylene laminate according to the invention comprises a polyethylene layer comprising a deposited film between the stretched polyethylene film and the heat-sealable polyethylene layer.
Thereby, the gas barrier properties of the polyethylene laminate according to the present invention can be improved.

The polyethylene layer provided with the deposited film may be composed of a stretched film or an unstretched film, but from the viewpoint of printability, strength and heat resistance of the polyethylene laminate, It is preferably stretched. In addition, it may be uniaxially stretched or biaxially stretched, but from the viewpoint of strength, biaxially stretched is preferred.

The polyethylene layer with the vapor deposited film can be made of high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE) and linear low density polyethylene (LLDPE), copolymers of ethylene and other monomers. including at least one. Among these, from the viewpoint 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 load, these polyethylenes are preferably derived from biomass.

The content of polyethylene in the polyethylene layer provided with the vapor-deposited film is preferably 50% by mass or more, more preferably 70% by mass or more.

The polyethylene layer provided with the deposited film may contain additives within the range that does not impair the characteristics of the present invention. Examples include inhibitors, pigments, and modifying resins.

From the viewpoint of productivity and economy, the thickness of the polyethylene layer provided with the 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.
Moreover, the thickness of the 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 setting the thickness of the vapor deposition film within the above numerical range, it is possible to prevent cracks and the like from occurring in the vapor deposition film while maintaining gas barrier properties.

The polyethylene layer with the vapor deposited film may have an image formed on its surface. The image forming method is as described above.

The polyethylene layer provided with a vapor-deposited film is produced by forming a polyethylene film from a resin material containing polyethylene by a melt extrusion molding method such as inflation molding or T-die molding, and the above-described film is formed on at least one surface of the polyethylene film. After forming a vapor deposition film by the above method, it can be formed by laminating it on a stretched polyethylene film via an adhesive. In this case, the polyethylene film may be stretched before vapor deposition and before lamination.
A polyethylene layer having a deposited film can also be formed by extruding a resin material containing polyethylene onto a stretched polyethylene film, drying it, and then forming a deposited film.

<Packaging material>
In one embodiment, the packaging material according to the present invention can be produced by folding the polyethylene laminate in two so that the heat-sealable polyethylene layer of the polyethylene laminate is on the inside, and heat-sealing the edges. can.
Alternatively, two polyethylene laminates can be produced by stacking two polyethylene laminates so that the heat-sealable polyethylene layers face each other and heat-sealing the edges.
Depending on the sealing method, for example, side seal type, two side seal type, three side seal type, four side seal type, envelope seal type, palm joint seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type Various forms of packaging material can be produced by heat-sealing by heat-sealing forms such as molds, gussets, and the like.
In addition, for example, a self-supporting packaging bag (standing pouch) or the like is also possible. As the heat sealing method, known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing can be used.

The polyethylene laminate according to the present invention, even if it is a laminate made of only one type of resin (that is, polyethylene), satisfies the strength and printability required as an outer film of a packaging material by an oriented polyethylene film, and has a heat-sealable polyethylene layer. enables packaging. Therefore, it is extremely suitable as a material constituting a packaging material that requires recyclability.

EXAMPLES The present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

<Example 1>
Medium-density polyethylene (density: 0.941 g/cm ³ , melting point: 129° C., MFR: 1.3 g/10 min, manufactured by Dowchemical, trade name: Elite 5538G) was formed by an inflation molding method to form a polyethylene film having a thickness of 100 μm. got
This polyethylene film was stretched in the longitudinal direction (MD) at a draw ratio of 5 times to obtain a stretched polyethylene film with a thickness of 20 μm. JIS for the haze value of stretched polyethylene film
When measured according to K-7105, it was 6.5%.

The stretched polyethylene film and an unstretched linear low-density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., trade name: L6100) with a thickness of 40 μm are combined with a two-component curable urethane adhesive (Rock Paint ( Co., Ltd., trade name: RU-77T/H-7) to obtain a polyethylene laminate.

<Example 2>
High-density polyethylene (density: 0.961 g/cm ³ , melting point: 135°C, MFR: 0.7 g/10 min, manufactured by ExxonMobil, trade name: HTA108) and medium-density polyethylene (density: 0.941 g/cm ³ , melting point: 129° C., MFR: 1.3 g/10 min, manufactured by Dowchemical, trade name: Elite 5538G) is formed by an inflation molding method to form a polyethylene film consisting of a high-density polyethylene layer/medium-density polyethylene layer/high-density polyethylene layer. made. The thickness of the high-density polyethylene layers was 20 μm each, and the thickness of the medium-density polyethylene layers was 60 μm.
This polyethylene film was stretched in the longitudinal direction (MD) at a draw ratio of 5 times to obtain a stretched polyethylene film with a thickness of 20 μm. The stretched polyethylene film had a haze value of 8.9%.

The stretched polyethylene film and an unstretched linear low-density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., trade name: L6100) with a thickness of 40 μm are combined with a two-component curable urethane adhesive (Rock Paint ( Co., Ltd., trade name: RU-77T/H-7) to obtain a polyethylene laminate.

<Example 3>
Medium-density polyethylene (density: 0.941 g/cm ³ , melting point: 129° C., MFR: 1.3 g/10 min, manufactured by Dowchemical, trade name: Elite 5538G) was formed by an inflation molding method to form a polyethylene film having a thickness of 100 μm. got
This polyethylene film was stretched in the machine direction (MD) and the width direction (TD) at a draw ratio of 2.24 times to obtain a stretched polyethylene film with a thickness of 20 μm. The haze value of the stretched polyethylene film was measured according to JIS K-7105 and found to be 5.1%.
The stretched polyethylene film and an unstretched linear low-density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., trade name: L6100) with a thickness of 40 μm are combined with a two-component curable urethane adhesive (Rock Paint ( Co., Ltd., trade name: RU-77T/H-7) to obtain a polyethylene laminate.

<Comparative Example 1>
Medium-density polyethylene (density: 0.941 g/cm ³ , melting point: 129° C., MFR: 1.3 g/10 min, manufactured by Dowchemical, trade name: Elite 5538G) was formed by an inflation molding method to form a 20 μm thick polyethylene film. got The haze value of the polyethylene film was measured according to JIS K-7105 and found to be 23.5%.

The above polyethylene film and a 40 μm thick unstretched linear low density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., trade name: L6100) are combined with a two-component curable urethane adhesive (Rock Paint Co., Ltd. ), trade name: RU-77T/H-7) to obtain a polyethylene laminate.

<Comparative Example 2>
High-density polyethylene (density: 0.961 g/cm ³ , melting point: 135°C, MFR: 0.7 g/10 min, manufactured by ExxonMobil, trade name: HTA108) and medium-density polyethylene (density: 0.941 g/cm ³ , melting point: 129° C., MFR: 1.3 g/10 min, manufactured by Dowchemical, trade name: Elite 5538G) is formed by an inflation molding method to form a polyethylene film consisting of a high-density polyethylene layer/medium-density polyethylene layer/high-density polyethylene layer. made. The thickness of the high-density polyethylene layers was 4 μm, and the thickness of the medium-density polyethylene layers was 12 μm. The haze value of the polyethylene film was measured according to JIS K-7105 and found to be 28.8%.

The above polyethylene film and a 40 μm thick unstretched linear low density polyethylene (LLDPE) film (manufactured by Toyobo Co., Ltd., trade name: L6100) are combined with a two-component curable urethane adhesive (Rock Paint Co., Ltd. ), trade name: RU-77T/H-7) to obtain a polyethylene laminate.

<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 oriented polyethylene film and the polyethylene film was evaluated based on the following evaluation criteria. The evaluation results are summarized in Table 1.
(Evaluation criteria)
◯: Dimensional stability during printing was good, and a good image free from rubbing, blurring, etc. could be formed.
x: Expansion and contraction of the film occurred during printing, and rubbing and blurring occurred in the formed image.

<Rigidity evaluation>
The stretched polyethylene films and polyethylene films produced in the above Examples and Comparative Examples were used as test pieces having a width of 15 mm, and the stiffness was measured using a loop stiffness measurement tester (manufactured by Toyo Seiki Seisakusho, trade name: Loop Stiffness Tester). In addition, the length of the loop was set to 60 mm. Table 1 summarizes the measurement results.

<Strength evaluation>
The stretched polyethylene films and polyethylene films produced in the above examples and comparative examples were used as dumbbell-shaped test pieces with a width of 10 mm. The tensile strength of this test piece in the MD direction was measured using a tensile tester (RTC-1310A manufactured by Orientec). The chuck-to-chuck distance was 10 mm, and the pulling speed was 300 mm/min. Table 1 summarizes the measurement results.

10: Polyethylene laminate for packaging material 20: Stretched polyethylene film 30: Heat-sealable polyethylene layer 40: Polyethylene layer provided with vapor deposition film

Claims (8)

At least a stretched polyethylene film layer printed on at least one surface and a heat-sealable polyethylene layer,
The stretched polyethylene film layer has a thickness of 9 μm or more and 50 μm or less,
The haze value of the stretched polyethylene film layer measured according to JIS K-7105 is 20% or less.
A polyethylene laminate for packaging materials, characterized by: 2. The polyethylene laminate for packaging material according to claim 1, wherein said oriented polyethylene film layer comprises at least one of high density polyethylene (HDPE) and medium density polyethylene (MDPE). The polyethylene laminate for packaging material according to claim 1 or 2, wherein the draw ratio in the longitudinal direction (MD) of the stretched polyethylene film layer is 2 times or more and 10 times or less. The polyethylene laminate for packaging material according to any one of claims 1 to 3, wherein the stretched polyethylene film layer has a structure of high-density polyethylene layer/medium-density polyethylene layer/high-density polyethylene layer. The polyethylene laminate for packaging material according to any one of claims 1 to 4, wherein the stretched polyethylene film layer is produced by an inflation molding method. The polyethylene laminate for packaging material according to any one of claims 1 to 5, wherein a print is formed on the heat-sealable polyethylene layer side of the stretched polyethylene film layer. Polyethylene laminate for packaging materials according to any one of the preceding claims, wherein said heat-sealable polyethylene layer comprises at least one of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). body. A packaging material composed of the laminate according to any one of claims 1 to 7.

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