JP2023048882A - Laminate, packaging material, and packaging container - Google Patents

Abstract

To improve a content ratio of polyethylene in a laminate having a stretchable polyethylene base material and a polyethylene layer as a sealant layer.SOLUTION: A laminate has a stretchable polyethylene base material and a sealant layer, wherein the stretchable polyethylene base material contains polyethylene as a main component, the sealant layer contains polyethylene as a main component, and the laminate has an extrusion resin layer containing polyethylene as a main component between the stretchable base material and the sealant layer.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to laminates, packaging materials and packaging containers.

Film products are manufactured by laminating films of different materials (for example, a polyester film as a substrate and a polyethylene film as a sealant layer) in order to exhibit various functions (for example, Patent Document 1 reference). Packaging containers are produced from such film products.

JP 2013-095454 A

In recent years, efforts to address environmental problems such as marine plastic pollution and global warming have been emphasized. Therefore, packaging materials and the like are required to have high recyclability. However, it is generally difficult to separate film products manufactured by laminating films made of different materials together, and there is a problem that it is difficult to recycle the films. In order to solve this problem, a technique called mono-materialization is being studied, in which film products are manufactured by laminating polyethylene films of the same kind of material to improve recyclability.

A monomaterial made of polyethylene can be realized by bonding polyethylene films having different characteristics, for example, by bonding a stretched polyethylene film as a substrate and a polyethylene film as a sealant layer. However, when a conventional non-polyethylene adhesive is used to bond polyethylene films together, the content of polyethylene decreases, which may cause deterioration in the physical properties of the material after recycling.

One problem to be solved by the present disclosure is to improve the content of polyethylene in a laminate including an oriented polyethylene base material and a polyethylene layer as a sealant layer.

A first laminate of the present disclosure includes a stretched polyethylene substrate and a sealant layer, the stretched polyethylene substrate contains polyethylene as a main component, the sealant layer contains polyethylene as a main component, and the laminate is provided with an extruded resin layer containing polyethylene as a main component between the stretched polyethylene substrate and the sealant layer.
The second laminate of the present disclosure comprises an extruded polyethylene base material and a sealant layer, the extruded polyethylene base material containing polyethylene as a main component, and the sealant layer containing polyethylene as a main component. is.

According to the present disclosure, it is possible to improve the content of polyethylene in a laminate including an oriented polyethylene base material and a polyethylene layer as a sealant layer.

FIG. 1 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. FIG. 2 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. FIG. 3 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. Figure 4 is a perspective view of one embodiment of a standing pouch. Figure 5 is a perspective view of one embodiment of a standing pouch.

Hereinafter, embodiments of the present disclosure will be described in detail. This disclosure may be embodied in many different forms and should not be construed as limited to the description of the illustrative embodiments below. In order to make the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each layer compared to the embodiment, but this is only an example and does not limit the interpretation of the present disclosure. . In this specification and each figure, elements similar to those already described with respect to previous figures may be denoted by the same reference numerals, and detailed description thereof may be omitted as appropriate.

[Laminate]
A first laminate of the present disclosure comprises an oriented polyethylene substrate and a polyethylene layer as a sealant layer. A first laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component between an oriented polyethylene base material and a sealant layer.

A second laminate of the present disclosure comprises an oriented polyethylene substrate and a polyethylene layer as a sealant layer. In the second laminate of the present disclosure, the sealant layer (polyethylene layer) is an extruded resin layer containing polyethylene as a main component.
The first laminate and the second laminate of the present disclosure are also collectively referred to as "the laminate of the present disclosure".

In one embodiment of the laminate of the present disclosure, the stretched polyethylene base material and the sealant layer each contain polyethylene, which is the same type of resin material, as a main component. By using a laminate having such a configuration, for example, a packaging container with excellent recyclability can be produced.

In the present disclosure, “AAA contains polyethylene as the main component”, “AAA containing polyethylene as the main component”, or similar descriptions mean that the content of polyethylene in the AAA is more than 50% by mass. However, it is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

For example, polyethylene includes high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene, and these are classified into the same type of resin material. On the other hand, for example, polyethylene and polyester are not classified as the same type of resin material.

In the present disclosure, polyethylene refers to a polymer containing 50 mol % or more of ethylene-derived structural units in all repeating structural units. In this polymer, the content of ethylene-derived structural units is preferably 70 mol % or more, more preferably 80 mol % or more, still more preferably 90 mol % or more, and particularly preferably 95 mol % or more. The content ratio can be measured by the NMR method.

In the present disclosure, polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and an ethylenically unsaturated monomer other than ethylene. Examples of ethylenically unsaturated monomers other than ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene. , 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene and 6-methyl-1-heptene, α-olefins having 3 to 20 carbon atoms; vinyls such as vinyl acetate and vinyl propionate monomers; and (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate.

In the present disclosure, polyethylene includes, for example, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene and ultra low density polyethylene.

In the present disclosure, the density of the polyethylene is as follows.
The density of high density polyethylene is preferably 0.945 g/cm ³ or higher. The upper density limit of high-density polyethylene is, for example, 0.965 g/cm ³ . The density of medium density polyethylene is preferably 0.925 g/cm ³ or more and less than 0.945 g/cm ³ . The density of the low-density polyethylene is preferably 0.900 g/cm ³ or more and less than 0.925 g/cm ³ . The linear low-density polyethylene preferably has a density of 0.900 g/cm ³ or more and less than 0.925 g/cm ³ . The density of ultra-low density polyethylene is preferably less than 0.900 g/ ^cm3 . The lower limit of the density of ultra-low density polyethylene is, for example, 0.860 g/cm ³ . The density of polyethylene is measured according to JIS K7112, particularly D method (density gradient tube method, 23°C).

Low-density polyethylene is usually polyethylene obtained by polymerizing ethylene by a high-pressure polymerization method. Linear low-density polyethylene is usually polyethylene obtained by polymerizing ethylene and a small amount of α-olefin by a low-pressure polymerization method (eg, a polymerization method using a Ziegler-Natta catalyst or a metallocene catalyst).

Polyethylenes with different densities or branches can be obtained by appropriately selecting the 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, one-stage polymerization is performed by any of gas phase polymerization, slurry polymerization, solution polymerization and high-pressure ion polymerization. Alternatively, it is preferable to carry out the polymerization in two or more stages.

A 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 structure of active sites than a multi-site catalyst, and is therefore preferable because a polymer having a high molecular weight and a highly uniform structure can be obtained.

A metallocene catalyst is preferred as the single-site 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 co-catalyst, optionally an organometallic compound, and optionally a carrier.

Examples of transition metals in transition metal compounds include zirconium, titanium and hafnium, with zirconium and hafnium being preferred.

The cyclopentadienyl skeleton in the transition metal compound is a cyclopentadienyl group or a substituted cyclopentadienyl group. Substituted cyclopentadienyl groups include, for example, 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, and haloalkyl groups. , and halosilyl groups. A substituted cyclopentadienyl group has one or more substituents, and the substituents are bonded to each other to form a ring, an indenyl ring, a fluorenyl ring, an azulenyl ring, or a hydrogenation product thereof. may be formed. A ring formed by combining substituents with each other may further have a substituent.

A transition metal compound usually has two ligands having a cyclopentadienyl skeleton. Each ligand having a cyclopentadienyl skeleton is preferably linked to each other by a bridging group. Examples of the cross-linking group include an alkylene group having 1 to 4 carbon atoms, a silylene group, a substituted silylene group such as a dialkylsilylene group and a diarylsilylene group, and a substituted germylene group such as a dialkylgermylene group and a diarylgermylene group. . Among these, substituted silylene groups are preferred.

A co-catalyst is a component that allows a transition metal compound of group IV of the periodic table to function effectively as a polymerization catalyst, or a component that balances ionic charges in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes, benzene-insoluble organoaluminumoxy compounds, ion-exchange layered silicates, boron compounds, and ions composed of cations containing or not containing active hydrogen groups and non-coordinating anions. lanthanide salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing fluoro groups.

Optional organometallic compounds include, for example, organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Among these, organoaluminum compounds are preferred.

The transition metal compound may be supported on an inorganic or organic compound carrier before use. As the carrier, porous oxides _of inorganic or organic compounds are preferred, and specific examples include ion-exchange layered silicates such as montmorillonite, _SiO2 , _Al2O3 , MgO, _ZrO2 , _TiO2 , and _B2O . ₃ , CaO, ZnO, BaO, _ThO2 , or mixtures thereof.

In the present disclosure, polyethylene derived from biomass (hereinafter also referred to as “biomass polyethylene”) may be used as polyethylene. That is, as a raw material for obtaining polyethylene, ethylene derived from biomass may be used instead of ethylene derived from fossil fuel. Since biomass polyethylene is a carbon-neutral material, it can reduce the environmental impact of laminates or packaging materials. Biomass polyethylene can be produced, for example, by the method described in JP-A-2013-177531. Commercially available biomass polyethylene may be used.

Biomass-derived ethylene, which is a raw material for biomass polyethylene, can be obtained by a conventionally known method. An example of a method for producing biomass-derived ethylene will be described below.

Biomass-derived ethylene can be produced, for example, using biomass-derived ethanol as a raw material. In particular, it is preferable to use biomass-derived fermented ethanol obtained from plant raw materials. Conventionally known plants such as corn, sugar cane, beet and manioc can be used as the plant raw material.

Biomass-derived fermented ethanol refers to ethanol produced by contacting a culture solution containing a carbon source obtained from a plant material with a microorganism that produces ethanol or a product derived from a crushed product thereof, and then refining the ethanol. Conventionally known methods such as distillation, membrane separation and extraction can be applied to purify ethanol from the culture medium. For example, a method of adding benzene, cyclohexane or the like to cause azeotropy, or removing water by membrane separation or the like can be mentioned. In order to obtain the above ethylene, at this stage, advanced purification such as reducing the total amount of impurities in ethanol to 1 ppm or less may be further performed.

A catalyst is usually used to obtain ethylene by the dehydration reaction of ethanol. A conventionally known catalyst can be used as the catalyst. A reaction form that is advantageous in terms of process is a fixed bed flow reaction that facilitates separation of the catalyst and the product. For example, γ-alumina is preferred.

Since this dehydration reaction is an endothermic reaction, it is usually carried out under heating conditions. Although the heating temperature is not limited as long as the reaction proceeds at a commercially useful reaction rate, a temperature of preferably 100° C. or higher, more preferably 250° C. or higher, and even more preferably 300° C. or higher is suitable. Although the upper limit is not particularly limited, it is preferably 500° C. or less, more preferably 400° C. or less from the viewpoint of energy balance and equipment.

In the dehydration reaction of ethanol, the yield of the reaction depends on the amount of water contained in ethanol supplied as a raw material. In general, when a dehydration reaction is performed, it is preferable that there is no water in consideration of water removal efficiency. However, in the case of ethanol dehydration using a solid catalyst, the absence of water tends to increase the amount of other olefins, especially butenes. It is presumed that ethylene dimerization after dehydration cannot be suppressed unless a small amount of water is present. The content of water is, for example, 0.1% by mass or more, preferably 0.5% by mass or more. The content of water is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, from the viewpoint of material balance and heat balance.

By carrying out the dehydration reaction of ethanol in this way, a mixture of ethylene, water and a small amount of unreacted ethanol is obtained. Since ethylene is a gas at room temperature of about 5 MPa or less, ethylene can be obtained by removing water and ethanol from the mixture by gas-liquid separation. This may be done by a known method.

Ethylene obtained by gas-liquid separation is further distilled, and the distillation method, operating temperature, residence time, etc. are not particularly limited except that the operating pressure at this time is normal pressure or higher.

When the raw material is biomass-derived ethanol, the resulting ethylene contains carbonyl compounds such as ketones, aldehydes, and esters that are impurities mixed in the ethanol fermentation process, carbon dioxide that is their decomposition products, and enzymatic decomposition products and contaminants. Nitrogen-containing compounds such as amines and amino acids, which are substances, and ammonia, etc., which are decomposition products thereof, are contained in extremely small amounts. Depending on the use of ethylene, these trace amounts of impurities may pose a problem, so they may be removed by refining. Purification can be performed by a conventionally known method. Suitable purification operations include, for example, adsorption purification methods. As the adsorbent to be used, a conventionally known adsorbent can be used. For example, a material with a high surface area is preferable, and the type of adsorbent is selected according to the type and amount of impurities in ethylene obtained by the dehydration reaction of biomass-derived ethanol.

As a method for purifying impurities in ethylene, caustic water treatment may be used in combination. When caustic water treatment is performed, it is desirable to perform it before adsorption purification. In that case, after the caustic treatment, it is necessary to apply moisture removal treatment before adsorption purification.

Biomass polyethylene is polyethylene obtained by polymerizing a monomer containing biomass-derived ethylene. As the biomass-derived ethylene, it is preferable to use ethylene obtained by the above production method. Since biomass-derived ethylene is used as a raw material monomer, the polymerized polyethylene is biomass-derived.

Raw material monomers for biomass polyethylene may not contain 100% by mass of biomass-derived ethylene. Raw material monomers for biomass polyethylene may further contain ethylene derived from fossil fuels in addition to ethylene derived from biomass.

Since carbon dioxide in the atmosphere contains a certain proportion of C14 (105.5 pMC), the C14 content in plants that grow by taking in carbon dioxide in the atmosphere, such as corn, is also about 105.5 pMC. It is known. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the ratio of C14 contained in all carbon atoms, the ratio of biomass-derived carbon can be calculated. In the present disclosure, “biomass degree” indicates the weight ratio of biomass-derived components. Take polyethylene terephthalate, for example. Polyethylene terephthalate is a polymer obtained by polymerizing ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms in a molar ratio of 1:1. When only biomass-derived ethylene glycol is used, the weight ratio of the biomass-derived component in the polyester is 31.25%. Therefore, the theoretical value of biomass degree is 31.25%. Specifically, the mass of polyethylene terephthalate is 192, of which the mass derived from biomass-derived ethylene glycol is 60. Therefore, 60÷192×100=31.25. The weight ratio of the biomass-derived component in the fossil fuel-derived polyester produced using fossil fuel-derived ethylene glycol and fossil fuel-derived dicarboxylic acid is 0%, and the biomass degree of the fossil fuel-derived polyester is 0%. is. Hereinafter, unless otherwise specified, the “biomass degree” indicates the weight ratio of biomass-derived components.

Theoretically, if all biomass-derived ethylene is used as the raw material for polyethylene, the biomass-derived ethylene concentration is 100%, and the biomass degree of biomass polyethylene is 100%. The concentration of biomass-derived ethylene in fossil fuel polyethylene produced only from fossil fuel-derived raw materials is 0%, and the biomass degree of fossil fuel polyethylene is 0%.

Specific examples of biomass polyethylene include biomass high-density polyethylene, biomass medium-density polyethylene, biomass low-density polyethylene, biomass linear low-density polyethylene, and biomass ultra-low density polyethylene. The biomass degree of biomass polyethylene is 80% or more, 85% or more, 90% or more, or 95% or more in one embodiment.
Biomass polyethylene is preferably plant-derived polyethylene.

In the present disclosure, biomass polyethylene and biomass-derived resin layers do not need to have a biomass degree of 100%. This is because if a biomass-derived raw material is used for even a part of the laminate, it is in line with the idea of reducing the amount of fossil fuel used compared to the past.

The biomass degree of the laminate of the present disclosure may be, for example, 5% or more and 70% or less, 8% or more and 40% or less, or 10% or more and 30% or less. This makes it possible, for example, to reduce the environmental impact of the laminate or packaging material.

As polyethylene, polyethylene recycled by mechanical recycling or chemical recycling may be used. As a result, the environmental impact of the laminate or packaging material can be reduced. Mechanical recycling generally involves pulverizing collected polyethylene film, washing with alkali to remove dirt and foreign matter from the surface of the film, and then drying it for a certain period of time under high temperature and reduced pressure until it remains inside the film. This is a method of decontaminating by diffusing contaminants, removing dirt from the film, and returning it to polyethylene again. Chemical recycling is generally a method of decomposing a recovered polyethylene film or the like down to the level of monomers and polymerizing the monomers again to obtain polyethylene.
The description of polyethylene above is applicable to polyethylene in the description below.

The content of polyethylene in the entire laminate of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. In the present disclosure, as described later, an extruded resin layer containing polyethylene as a main component is used as an adhesive layer or a sealant layer, so the content of polyethylene can be increased. Since such a laminate uses polyethylene, which is a resin material of the same kind, it can be classified as a so-called mono-material material, and can be suitably used, for example, for producing a mono-material packaging container.

1 and 2 show an embodiment of the first laminate of the present disclosure. The laminate 1 of FIG. 1 includes an oriented polyethylene substrate 10, an extruded resin layer 20, and a sealant layer 30 in this order in the thickness direction. The laminate 1 of FIG. 2 further includes an anchor coat layer 22 between the stretched polyethylene base material 10 and the extruded resin layer 20 . The extruded resin layer 20 is in contact with the anchor coat layer 22 .

FIG. 3 shows one embodiment of the second laminate of the present disclosure. The laminate 1 of FIG. 3 includes an oriented polyethylene base material 10, an anchor coat layer 22, and an extruded resin layer 20 as a sealant layer in this order in the thickness direction. The extruded resin layer 20 is in contact with the anchor coat layer 22 .

In one embodiment, the laminate 1 further comprises a printed layer (not shown) on the stretched polyethylene substrate 10 . The printed layer is formed, for example, on the extruded resin layer 20 side surface of the stretched polyethylene base material 10 . The printed layer is positioned, for example, between the stretched polyethylene base material 10 and the extruded resin layer 20 (the anchor coat layer 22 when the anchor coat layer 22 is provided).

<Stretched polyethylene base material>
The stretched polyethylene base material contains polyethylene as a main component. The resin material constituting the stretched polyethylene base material is polyethylene, which is the same resin material as the resin material constituting the sealant layer. It can be suitably used as a laminate.

Details of the polyethylene are as described above. From the viewpoint of the strength and heat resistance of the stretched polyethylene substrate, high-density polyethylene and medium-density polyethylene are preferred, and from the viewpoint of stretchability, medium-density polyethylene is preferred.

The melt flow rate (MFR) of the polyethylene constituting the stretched polyethylene substrate is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably It is 0.2 g/10 min or more and 30 g/10 min or less, more preferably 0.2 g/10 min or more and 10 g/10 min or less, and particularly preferably 0.2 g/10 min or more and 5.0 g/10 min or less. The MFR of polyethylene is measured by A method in accordance with JIS K7210 under conditions of a temperature of 190° C. and a load of 2.16 kg.

For example, when a stretched polyethylene base material is produced by the T-die method, the MFR of the polyethylene constituting the stretched polyethylene base material is preferably 3.0 g/10 min or more and 20 g/10 min or less from the viewpoint of film formability and processability. is.

For example, when a stretched polyethylene base material is produced by an inflation method, the MFR of the polyethylene constituting the stretched polyethylene base material is preferably 0.2 g/10 min or more and 5.0 g/10 min from the viewpoint of film formability and processability. It is below.

From the viewpoint of heat resistance, the melting point (Tm) of the polyethylene constituting the stretched polyethylene substrate is preferably 100° C. or higher and 140° C. or lower, more preferably 110° C. or higher and 140° C. or lower, and still more preferably 120° C. or higher and 140° C. or lower. be. Tm is obtained by differential scanning calorimetry (DSC) according to JIS K7121.

The stretched polyethylene substrate can contain one or more polyethylenes.
The content of polyethylene in the stretched polyethylene substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, the recyclability of the laminate can be improved.

When the stretched polyethylene substrate has a multilayer structure, the content of polyethylene in each layer constituting the substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass. That's it. With such a configuration, for example, the recyclability of the laminate can be improved.

The stretched polyethylene substrate may contain one or more resin materials other than polyethylene. Examples of the resin material include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. When the stretched polyethylene substrate has a multilayer structure, each layer constituting the substrate can independently contain the resin material.

The stretched polyethylene substrate may contain one or more additives. Examples of additives include cross-linking agents, anti-blocking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes and modifying resins. is mentioned. When the stretched polyethylene base material has a multilayer structure, each layer constituting the base material can independently contain the above additives.

A stretched polyethylene base material is a polyethylene base material that has been stretched. The stretching treatment can improve, for example, the heat resistance and strength of the polyethylene base material. Such a stretched polyethylene base material can satisfy the physical properties required, for example, as an outer layer of a packaging material.

The stretching may be uniaxial stretching or biaxial stretching. In one embodiment, the draw ratio in the longitudinal direction (MD) of the stretched polyethylene substrate is preferably 2 times or more and 10 times or less, more preferably 3 times or more and 7 times or less. In one embodiment, the draw ratio in the transverse direction (TD) of the stretched polyethylene substrate is preferably 2 times or more and 10 times or less, more preferably 3 times or more and 7 times or less.

When the draw ratio is 2 times or more, for example, the rigidity, strength and heat resistance of the substrate can be improved, the printability of the substrate can be improved, and the transparency of the substrate can be improved. If the draw ratio is 10 times or less, for example, the film can be stretched satisfactorily without causing breakage or the like.

The oriented polyethylene substrate, in one embodiment, is a uniaxially oriented film, more specifically a uniaxially oriented film that has been stretched in the machine direction (MD).

The stretched polyethylene substrate may have a single layer structure or a multilayer structure. Hereinafter, a stretched polyethylene base material having a multilayer structure is also referred to as a "stretched multilayer base material". A stretched multilayer base material is preferable from the viewpoint of being able to improve its strength, heat resistance and stretchability.

A stretched multilayer substrate has a multilayer structure of two or more layers. In one embodiment, the number of layers of the stretched multilayer substrate is 2 or more and 7 or less, for example, 3 or more and 7 or less, or 3 or more and 5 or less. The number of layers of the stretched multilayer substrate is preferably an odd number, such as 3, 5 or 7 layers. When the stretched multilayer base material has a multilayer structure, the balance of rigidity, strength, heat resistance, printability and stretchability of the base material can be improved. Each layer of the stretched multilayer substrate also preferably contains polyethylene as a main component.

Several examples of embodiments of the stretched multilayer substrate are described below. Hereinafter, a layer having a high density polyethylene content of 80% by mass or more is referred to as a "high density polyethylene layer", and a layer having a medium density polyethylene content of 80% by mass or more is referred to as a "medium density polyethylene layer". A layer having a low-density polyethylene content of 80% by mass or more is referred to as a “low-density polyethylene layer”, and a layer having a linear low-density polyethylene content of 80% by mass or more is referred to as a “linear low-density polyethylene layer”. A layer containing 80% by mass or more of ultra-low-density polyethylene is referred to as an "ultra-low-density polyethylene layer".

The stretched multilayer base material of the first embodiment comprises a high-density polyethylene layer and a medium-density polyethylene layer in this order in the thickness direction. By using a high-density polyethylene layer as the surface resin layer of the substrate, for example, the strength and heat resistance of the substrate can be improved. By including the medium-density polyethylene layer in the base material, for example, the stretching aptitude of the pre-stretching laminate can be improved.

The stretched multilayer base material of the second embodiment includes a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer in this order in the thickness direction. With such a configuration, for example, the strength and heat resistance of the base material can be improved, the occurrence of curling in the base material can be suppressed, and the stretching aptitude of the unstretched laminate can be improved.

In the stretched multilayer substrates of the first and second embodiments, the thickness of the high-density polyethylene layer is preferably equal to or less 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 (high-density polyethylene layer/medium-density polyethylene layer) is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less. is.

The stretched multilayer substrate of the third embodiment includes 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 (for simplicity of description, these The three layers are collectively described as "a low-density polyethylene layer, etc."), a medium-density polyethylene layer, and a high-density polyethylene layer are provided in this order in the thickness direction. With such a configuration, for example, the stretching aptitude of the laminate before stretching can be improved, the strength and heat resistance of the substrate can be improved, and the occurrence of curling in the substrate can be suppressed.

In the stretched multilayer base material of the third embodiment, the thickness of the high-density polyethylene layer is preferably equal to or less 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 (high-density polyethylene layer/medium-density polyethylene layer) is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less. is.

In the stretched multilayer base material of the third embodiment, the thickness of the high-density polyethylene layer is preferably equal to or greater than the thickness of the low-density polyethylene layer or the like. The ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer (high-density polyethylene layer/low-density polyethylene layer, etc.) is preferably 1 or more and 4 or less, more preferably 1 or more and 2 or less.

As a stretched multi-layer substrate of another embodiment, a high density polyethylene layer, a high density polyethylene layer, a blend layer of medium density polyethylene and high density polyethylene, a high density polyethylene layer, and a high density polyethylene layer are formed to a thickness of A substrate provided in this order in the direction; a medium density polyethylene layer, a high density polyethylene layer, a linear low density polyethylene layer, a high density polyethylene layer, and a medium density polyethylene layer in this order in the thickness direction. Materials are also included.

In addition, a high-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, a low-density polyethylene layer, etc., a blend layer of high-density polyethylene and medium-density polyethylene, and a high-density polyethylene layer are arranged in the thickness direction. Substrates provided in this order are also included.

The stretched multilayer substrate of the fourth embodiment includes a medium density polyethylene layer, a high density polyethylene layer, a blend layer of medium density polyethylene and high density polyethylene, a high density polyethylene layer, and a medium density polyethylene layer. Prepare in this order in the vertical direction. With such a configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretching laminate can be improved.

In the blend layer of medium density polyethylene and high density polyethylene, the mass ratio of medium density polyethylene to high density polyethylene (medium density polyethylene/high density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4. 2.4 or less.

The stretched multilayer base material of the fifth embodiment includes a medium density polyethylene layer, a medium density polyethylene layer, a blend layer of medium density polyethylene and linear low density polyethylene, a medium density polyethylene layer, and a medium density polyethylene layer. are provided in this order in the thickness direction. With such a configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretching laminate can be improved.

In the blend layer of medium density polyethylene and linear low density polyethylene, the mass ratio of medium density polyethylene to linear low density polyethylene (medium density polyethylene/linear low density polyethylene) is preferably 0.25 or more. 4 or less, more preferably 0.4 or more and 2.4 or less.

The stretched multilayer substrate of the sixth embodiment includes a blend layer of medium density polyethylene and high density polyethylene, a blend layer of medium density polyethylene and linear low density polyethylene, a linear low density polyethylene layer, and a medium density A blend layer of polyethylene and linear low density polyethylene and a blend layer of medium density polyethylene and high density polyethylene are provided in this order in the thickness direction. With such a configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretching laminate can be improved.

In the blend layer of medium density polyethylene and high density polyethylene, the mass ratio of medium density polyethylene to high density polyethylene (medium density polyethylene/high density polyethylene) is independently preferably 0.25 or more and 4 or less, more preferably is 0.4 or more and 2.4 or less.

In the blend layer of medium density polyethylene and linear low density polyethylene, the mass ratio of medium density polyethylene to linear low density polyethylene (medium density polyethylene/linear low density polyethylene) is preferably 0.25 or more. 4 or less, more preferably 0.4 or more and 2.4 or less.

The stretched multilayer substrate of the seventh embodiment includes a blend layer of high-density polyethylene and medium-density polyethylene, a medium-density polyethylene layer, a blend layer of linear low-density polyethylene and medium-density polyethylene, and a medium-density polyethylene layer. , a blend layer of high density polyethylene and medium density polyethylene in this order in the thickness direction. With such a configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretching laminate can be improved.

The mass ratio of medium density polyethylene to high density polyethylene (medium density polyethylene/high density polyethylene) in the blend layer of high density polyethylene and medium density polyethylene is independently preferably 0.25 or more and 4 or less, more preferably is 0.4 or more and 2.4 or less.

The mass ratio of linear low density polyethylene to medium density polyethylene (linear low density polyethylene/medium density polyethylene) in the blend layer of linear low density polyethylene and medium density polyethylene is preferably 0.25 or more. Below, it is more preferably 0.4 or more and 2.4 or less.

The stretched multilayer substrate of the eighth embodiment comprises a first layer containing medium density polyethylene and high density polyethylene, a second layer containing high density polyethylene, and a second layer containing linear low density polyethylene. 3 layers, a fourth layer containing high density polyethylene, and a fifth layer containing medium density polyethylene and high density polyethylene are provided in this order in the thickness direction.

The mass ratio of medium density polyethylene to high density polyethylene (medium density polyethylene/high density polyethylene) in the first layer and the fifth layer is preferably 1.1 or more and 5 or less, more preferably 1. 0.5 or more and 3 or less. This can further improve the balance between ink adhesion and heat resistance.

The total content of medium-density polyethylene and high-density polyethylene in the first layer and the fifth layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. is. This can further improve the ink adhesion and heat resistance of the substrate.

The second layer and the fourth layer may each independently further contain low density polyethylene. As a result, the balance of heat resistance, rigidity and workability of the base material can be further improved.

The mass ratio of high-density polyethylene to low-density polyethylene (high-density polyethylene/low-density polyethylene) in the second layer and the fourth layer is preferably 1 or more and 4 or less, more preferably 1.5. 3 or less. As a result, the balance of heat resistance, rigidity and workability of the base material can be further improved.

The content of high-density polyethylene in the second layer and the fourth layer is preferably more than 50% by mass, more preferably 55% by mass or more, and still more preferably 60% by mass or more. Thereby, the heat resistance of the substrate can be further improved.

The total content of high-density polyethylene and low-density polyethylene in the second layer and the fourth layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. is. As a result, the balance of heat resistance, rigidity and workability of the base material can be further improved.

The thickness of each of the second layer and the fourth layer is preferably 0.5 μm or more and 15 μm or less, more preferably 1 μm or more and 10 μm or less, and still more preferably 1 μm or more and 8 μm or less. Thereby, the heat resistance of the substrate can be further improved.

The third layer may further contain low density polyethylene.

The content of linear low-density polyethylene in the third layer is preferably more than 50% by mass, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, 90% by mass % or more, or 95% by mass or more. This can further improve the balance between heat resistance, rigidity and stretchability.

When the third layer contains low-density polyethylene, the content of low-density polyethylene is preferably less than 50% by mass, more preferably 5% to 40% by mass, and still more preferably 10% to 30% by mass. It is below.

The thickness of the third layer is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 40 μm or less, and still more preferably 5 μm or more and 30 μm or less. This can further improve the balance between heat resistance, rigidity and stretchability.

The ratio of the total thickness of the second layer and the fourth layer to the thickness of the third layer (total thickness of the second layer and the fourth layer/thickness of the third layer) is preferably 0.1 or more and 10 or less, more preferably 0.2 or more and 5 or less, and still more preferably 0.5 or more and 2 or less. Thereby, the rigidity, strength and heat resistance of the substrate can be further improved.

In the stretched multilayer substrates of the fourth to eighth embodiments, the thickness of each of the two surface resin layers is preferably 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 8 μm or less, and even more preferably is 1 μm or more and 5 μm or less. Thereby, for example, the heat resistance and printability of the substrate can be further improved.

In the stretched multilayer substrates of the fourth to eighth embodiments, the thickness of each of the two surface resin layers is preferably smaller than the total thickness of the inner three layers (multilayer intermediate layer). The ratio of the thickness of each of the two surface resin layers to the total thickness of the multilayer intermediate layer (surface resin layer/multilayer intermediate layer) is preferably from 0.05 to 0.8, more preferably from 0.1 to 0. 0.7 or less, more preferably 0.1 or more and 0.4 or less. Thereby, for example, the rigidity, strength and heat resistance of the substrate can be further improved.

In the present disclosure, at least one layer constituting the stretched multilayer substrate of the above embodiments may contain biomass polyethylene.

In the stretched multilayer base material, the density of polyethylene constituting each layer may be the same or different. For example, a stretched multi-layer substrate may have a gradient in the density of each layer (density gradient). By providing a density gradient in the stretched multilayer base material, for example, its strength, heat resistance and stretchability can be improved.

In a stretched multilayer substrate having a density gradient, the absolute value of the density difference between any two adjacent layers is preferably small. The absolute value of the density difference is preferably 0.040 g/cm ³ or less, more preferably 0.030 g/cm ³ or less, still more preferably 0.020 g/cm ³ or less. With such a configuration, for example, it is possible to effectively suppress the occurrence of delamination at the interface of each layer.

In the present disclosure, the density of each layer may be measured according to JIS K7112 above, or calculated from the density of the components constituting the layer. For example, if one layer contains a plurality of components (e.g., polyethylene) with different densities (n types; n is an integer of 2 or more), the average density D _av calculated according to the following formula (f1) is It may be the density of the layer.

D _av =ΣW _i ×D _i (f1)
In formula (f1), Σ means taking the sum of W _i ×D _i from 1 to n for i, n is an integer of 2 or more, and W _i is the mass fraction of the i-th component. and D _i indicates the density (g/cm ³ ) of the i-th component.

The haze value of the stretched polyethylene substrate is preferably 25% or less, more preferably 15% or less, and still more preferably 12% or less. A smaller haze value is more preferable, but in one embodiment, the lower limit may be 0.1% or 1%. The haze value of the substrate is measured according to JIS K7136.

The thickness of the stretched polyethylene substrate is preferably 10 μm or more and 60 μm or less, more preferably 15 μm or more and 50 μm or less. When the thickness of the substrate is 10 μm or more, the rigidity and strength of the laminate can be improved. When the thickness of the substrate is 60 μm or less, the workability of the laminate can be improved.

The stretched polyethylene base material may be surface-treated. Thereby, for example, the adhesion between the substrate and the layer laminated on the substrate can be improved. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using gases such as oxygen gas and nitrogen gas, glow discharge treatment; and oxidation treatment using chemicals. Chemical treatment can be mentioned. An anchor coat layer may be formed on the surface of the stretched polyethylene substrate using a conventionally known anchor coat agent.

The stretched polyethylene base material can be produced, for example, by forming a film of polyethylene or a polyethylene resin composition by an inflation method or a T-die method and stretching the film. The stretched multilayer base material can be produced, for example, by film-forming a plurality of polyethylenes or polyethylene resin compositions by an inflation method or a T-die method to form a laminate, and stretching the obtained laminate. The stretching treatment can improve the transparency, rigidity, strength and heat resistance of the polyethylene base material, and the base material can be suitably used as, for example, a base material for packaging materials. Stretching can also be performed in an inflation film forming machine.

In one embodiment, the stretched polyethylene substrate having a multilayer structure is a coextruded resin film, and each layer constituting the substrate is a coextruded resin layer. A co-extruded resin film can be produced, for example, by forming a film using an inflation method, a T-die method, or the like.

In one embodiment, the stretched multilayer substrate is obtained by stretching a laminate (precursor) having a multilayer structure. Specifically, the resin materials constituting each layer can be co-extruded into a tubular shape to form a film, thereby producing a laminate. Alternatively, a laminate can be produced by co-extrusion of the resin materials constituting each layer into a tubular shape, and then pressing the opposing layers together with a rubber roll or the like. By manufacturing a laminate by such a method, the number of defective products can be significantly reduced, and production efficiency can be improved.

The oriented polyethylene substrate, in one embodiment, contains biomass polyethylene. The biomass degree of the stretched polyethylene substrate in this case may be, for example, 10% or more, 10% or more and 65% or less, 20% or more and 55% or less, or 25% or more and 50% or less.

When the stretched polyethylene base material has a multilayer structure, that is, when the stretched polyethylene base material has two or more resin layers containing polyethylene as a main component, at least one of the resin layers may contain biomass polyethylene.

For example, a first resin layer containing high-density polyethylene as a main component, a second resin layer containing medium-density polyethylene as a main component, and a third resin layer containing high-density polyethylene as a main component are combined. The stretched polyethylene base material provided in this order in the thickness direction will be described. In this case, at least one selected from high-density polyethylene in the first resin layer, medium-density polyethylene in the second resin layer, and high-density polyethylene in the third resin layer may be biomass polyethylene.

<Deposited film>
In one embodiment, the laminate of the present disclosure may include a deposited film formed on the surface of the stretched polyethylene substrate on the sealant layer side. Thereby, for example, the oxygen barrier property and water vapor barrier property of the laminate can be improved.

Deposited films include, for example, metals such as aluminum, chromium, tin, nickel, copper, silver, gold, and platinum; or aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, and hafnium oxide. , barium oxide and silicon carbide oxide (carbon-containing silicon oxide). Among these, an aluminum vapor deposition film, an aluminum oxide (alumina) vapor deposition film, a silicon oxide (silica) vapor deposition film, or a carbon-containing silicon oxide vapor deposition film is preferable.

The carbon-containing silicon oxide deposited film contains silicon, oxygen and carbon.
In one embodiment of the carbon-containing silicon oxide deposited film, the proportion C of carbon is preferably 3% or more and 50% or less, more preferably 5% or more and 40% with respect to the total 100% of the three elements of silicon, oxygen and carbon. % or less, more preferably 10% or more and 35% or less. By setting the ratio C of carbon within the above range, for example, deterioration of the gas barrier property can be suppressed even when the laminate is bent.
In this specification, the ratio of each element is on a molar basis.

In one embodiment of the carbon-containing silicon oxide deposited film, the ratio Si of silicon is preferably 1% or more and 45% or less, more preferably 3% or more and 38% with respect to a total of 100% of the three elements of silicon, oxygen and carbon. % or less, more preferably 8% or more and 33% or less. The oxygen ratio O is preferably 10% or more and 70% or less, more preferably 20% or more and 65% or less, and still more preferably 25% or more and 60% or less with respect to 100% in total of the three elements of silicon, oxygen, and carbon. is. By setting the ratio Si of silicon and the ratio O of oxygen within the above ranges, for example, deterioration of gas barrier properties can be further suppressed even when the laminate is bent.

In one embodiment of the carbon-containing silicon oxide deposited film, the oxygen proportion O is preferably higher than the carbon proportion C, and the silicon proportion Si is preferably lower than the carbon proportion C. The proportion O of oxygen is preferably higher than the proportion Si of silicon, ie the respective proportions preferably decrease in the order of proportion O, proportion C and proportion Si. As a result, for example, even if the laminate is bent, deterioration of the gas barrier properties can be further suppressed.

The proportion C, the proportion Si and the proportion O in the carbon-containing silicon oxide deposited film can be measured by narrow scan analysis under the following measurement conditions by X-ray photoelectron spectroscopy (XPS).

(Measurement condition)
Equipment used: "ESCA-3400" (manufactured by Kratos)
[1] Spectrum collection conditions Incident X-ray: MgKα (monochromatic X-ray, hν = 1253.6 eV)
X-ray output: 150W (10kV/15mA)
X-ray scanning area (measurement area): about 6mmφ
Photoelectron capture angle: 90 degrees [2] Ion sputtering conditions Ion species: Ar ⁺
Acceleration voltage: 0.2 (kV)
Emission current: 20 (mA)
Etching range: 10mmφ
Ion sputtering time: 30 seconds, spectrum collected

The thickness of the deposited film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and still more preferably 10 nm or more and 40 nm or less. By setting the thickness of the deposited film to 1 nm or more, for example, the oxygen barrier property and water vapor barrier property of the laminate can be further improved. By setting the thickness of the deposited film to 150 nm or less, for example, it is possible to suppress the occurrence of cracks in the deposited film and improve the recyclability of the laminate.

Examples of methods for forming a deposited film include physical vapor deposition (PVD) such as vacuum deposition, sputtering and ion plating; plasma chemical vapor deposition, thermal chemical vapor deposition and photochemical vapor deposition. A chemical vapor deposition method (CVD method) such as a phase growth method can be used. The deposited film may be a composite film including two or more layers of deposited films of different kinds of inorganic oxides, which is formed using both physical vapor deposition and chemical vapor deposition.

The degree of vacuum in the vapor deposition chamber is preferably about 10 ^-2 to 10 ^-8 mbar before introducing oxygen, and about 10 ^-1 to 10 ^-6 mbar after introducing oxygen. The amount of oxygen to be introduced varies depending on the size of the vapor deposition machine. Inert gases such as argon gas, helium gas and nitrogen gas may be used as a carrier gas for oxygen to be introduced as long as there is no problem. The conveying speed of the target film on which the vapor deposition film is formed is, for example, 10 m/min or more and 800 m/min or less.

The surface of the deposited film may be subjected to the surface treatment described above. Thereby, for example, the adhesion between the deposited film and the layer adjacent to the deposited film can be improved.

<Barrier coat layer>
For example, when the deposited film is composed of inorganic oxides such as aluminum oxide and silicon oxide, a barrier coat layer may be provided on the surface of the deposited film. With such a configuration, for example, the gas barrier properties of the laminate can be improved, and the occurrence of cracks in the deposited film can be effectively suppressed.

In one embodiment, the barrier coat layer contains a gas barrier resin as a main component. Examples of gas barrier resins include ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyethylene terephthalate, polyesters such as polybutylene terephthalate and polyethylene naphthalate, nylon 6, nylon 6,6 and polymetaxylylene adipamide. Polyamides such as polyurethanes, and (meth)acrylic resins.

The content of the gas barrier resin in the barrier coat layer is preferably more than 50% by mass, more preferably 60% by mass or more, and even more preferably 70% by mass or more. With such a configuration, for example, the gas barrier properties of the barrier coat layer can be improved.

The thickness of the barrier coat layer is preferably 0.01 μm or more and 10.0 μm or less, more preferably 0.1 μm or more and 5.0 μm or less. By setting the thickness of the barrier coat layer to 0.01 μm or more, for example, gas barrier properties can be further improved.

The barrier coat layer can be formed by, for example, dissolving or dispersing a material such as a gas barrier resin in water or a suitable organic solvent, applying the obtained coating liquid, and drying. The barrier coat layer can also be formed by applying and drying a commercially available barrier coat agent.

In another embodiment, the barrier coat layer is a gas barrier obtained by mixing a metal alkoxide, a water-soluble polymer, and optionally a silane coupling agent, and adding water, an organic solvent, and a sol-gel catalyst. It is a gas-barrier coating layer formed by coating a vapor-deposited film with a gas-barrier composition and drying it. The gas barrier coating layer contains a hydrolyzed polycondensate obtained by hydrolyzing and polycondensing a metal alkoxide or the like by a sol-gel method. By providing such a barrier coat layer on the vapor deposition film, it is possible to effectively suppress the occurrence of cracks in the vapor deposition film. Each of the above components can be used alone or in combination of two or more.

A metal alkoxide is represented by Formula (1), for example.
^{R1nM (} _OR2 ) _m (1)
In formula (1), R ¹ and R ² each independently represent an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, and m is an integer of 1 or more. and n+m represents the valence of M.

Examples of organic groups for R ¹ and R ² include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, n-hexyl group and Examples thereof include alkyl groups having 1 to 8 carbon atoms such as n-octyl group.
Metal atoms M are, for example, silicon, zirconium, titanium or aluminum.

Examples of metal alkoxides include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

Examples of water-soluble polymers include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Either one of polyvinyl alcohol and ethylene-vinyl alcohol copolymer may be used, or both may be used in combination, depending on desired physical properties such as oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance. Alternatively, a gas barrier coating layer obtained using polyvinyl alcohol and a gas barrier coating layer obtained using an ethylene-vinyl alcohol copolymer may be laminated. The amount of the water-soluble polymer used is preferably 5 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the metal alkoxide.

As the silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used, and organoalkoxysilanes having an epoxy group are preferred, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Propylmethyldiethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are included. The amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the metal alkoxide.

The gas barrier composition may contain water in a proportion of preferably 0.1 mol or more and 100 mol or less, more preferably 0.5 mol or more and 60 mol or less, relative to 1 mol of the metal alkoxide. By making the water content equal to or higher than the lower limit, for example, the oxygen barrier properties and water vapor barrier properties of the laminate can be improved. By making the water content equal to or less than the upper limit, for example, the hydrolysis reaction can be carried out quickly.

Examples of organic solvents used for preparing gas barrier compositions include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol and n-butyl alcohol.

As the sol-gel process catalyst, an acid or amine compound is preferable.
Acids include, for example, mineral acids such as sulfuric acid, hydrochloric acid and nitric acid; and organic acids such as acetic acid and tartaric acid. The amount of the acid to be used is preferably 0.001 mol or more and 0.05 mol or less per 1 mol of the total molar amount of the alkoxide portion (for example, silicate portion) of the metal alkoxide and the silane coupling agent.

Amine compounds include, for example, N,N-dimethylbenzylamine, tripropylamine, tributylamine and tripentylamine. The amount of the amine compound used is preferably 0.01 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the total amount of the metal alkoxide and the silane coupling agent.

Examples of the method of applying the gas barrier composition include application means such as roll coating such as gravure roll coater, spray coating, spin coating, dipping, brush, bar coating and applicator.

An embodiment of the method for forming the gas barrier coating layer will be described below.
A gas barrier 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. A polycondensation reaction proceeds gradually in the composition. The above composition is applied onto the deposited film by a conventional method and dried. This drying further promotes polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains a silane coupling agent) to form a composite polymer layer. The above operation may be repeated to laminate a plurality of composite polymer layers. For example, the applied composition is heated at a temperature of preferably 20° C. to 150° C., more preferably 50° C. to 120° C., still more preferably 50° C. to 100° C. for 1 second to 10 minutes. Thereby, a gas barrier coating layer can be formed.

The thickness of the gas barrier coating layer is preferably 0.01 μm or more and 10.0 μm or less, more preferably 0.1 μm or more and 5.0 μm or less, and still more preferably 0.1 μm or more and 2.0 μm or less. Thereby, for example, the gas barrier property can be improved, and the occurrence of cracks in the deposited film can be suppressed.

<Print layer>
The laminate of the present disclosure, in one embodiment, may further comprise a printed layer formed on the stretched polyethylene substrate described above. In one embodiment, the laminate of the present disclosure preferably includes a printed layer on the sealant layer side surface of the stretched polyethylene base material, since deterioration of the image over time can be suppressed. When the laminate has a vapor deposition film or a barrier coat layer on the substrate, for example, a print layer may be provided on the sealant layer side of the vapor deposition film or barrier coat layer.

The print layer contains, for example, an image. Images include, for example, characters, graphics, symbols, and combinations thereof. Examples of methods for forming the printed layer include gravure printing, offset printing, and flexographic printing. In one embodiment, the flexographic printing method is preferred from the viewpoint of reducing environmental impact. Moreover, from the viewpoint of reducing the environmental burden, a printed layer may be formed on the surface of the base material or the like using biomass-derived ink.

The thickness of the printed layer is preferably 0.1 μm or more and 10.0 μm or less, more preferably 0.2 μm or more and 5.0 μm or less, and still more preferably 0.3 μm or more and 3.0 μm or less.

<Anchor coat layer>
In one embodiment, the laminate of the present disclosure may further include an anchor coat layer between the stretched polyethylene substrate and the extruded resin layer. Thereby, for example, the adhesion between layers in the laminate can be improved. The anchor coat layer is formed with an anchor coat agent. In this embodiment, the extruded resin layer is in contact with the anchor coat layer.

Examples of the anchor coating agent include polyurethane-based, polyolefin-based, and epoxy resin-based anchor coating agents. In one embodiment, the anchor coating agent is a two-pack curing resin, and is composed of, for example, polyol as a main agent and polyisocyanate as a curing agent.

Polyols include, for example, polyether polyols, polyester polyols and (meth)acrylic polyols. Polyisocyanates include, for example, aromatic polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate and polymethylene polyphenylene polyisocyanate, and aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate.

The anchor coat layer consists in one embodiment of a polyurethane obtained by reacting a polyol with a polyisocyanate. Polyurethanes specifically include polyether polyurethanes, polyester polyurethanes and poly(meth)acrylic polyurethanes.

The anchor coat layer can be formed, for example, by applying an anchor coating agent to the stretched polyethylene base material or the printed layer forming surface of the stretched polyethylene base material. The anchor coating agent can be applied, for example, by a coating method such as a roll coating method, a gravure roll coating method and a kiss coating method, or a printing method.

The thickness of the anchor coat layer is, for example, 0.05 μm or more and 3.0 μm or less, preferably 0.1 μm or more and 2.0 μm or less, more preferably 0.2 μm or more and 1.0 μm or less.

<Extruded resin layer>
A first laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component between an oriented polyethylene base material and a sealant layer. The extruded resin layer functions as an adhesive layer between the stretched polyethylene substrate and the sealant layer, or as an adhesive layer between the laminate comprising the stretched polyethylene substrate and the sealant layer. A laminate comprising an oriented polyethylene substrate, for example, comprises an oriented polyethylene substrate and other layers such as a printing layer and an anchor coat layer.

The first laminate of the present disclosure is provided with an extruded resin layer containing polyethylene as a main component as an adhesive layer between the stretched polyethylene base material or the laminate and the sealant layer, so that the conventional non-polyethylene adhesive ( For example, compared with the case of using a two-liquid curing type polyurethane adhesive), the content of polyethylene in the laminate can be increased. Thereby, the recyclability of the laminate can be improved.

The second laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component as a sealant layer. The second laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component as a surface layer on one side. Thereby, the content ratio of polyethylene in the laminate can be increased, and, for example, the recyclability of the laminate can be improved.

The extruded resin layer contains polyethylene as a main component. Details of the polyethylene are as described above. The polyethylene in the extruded resin layer and the polyethylene in the stretched polyethylene substrate may be the same or different.

In the first laminate of the present disclosure, the polyethylene constituting the extruded resin layer is preferably at least one selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene from the viewpoint of adhesiveness. , low density polyethylene or linear low density polyethylene are more preferred. Biomass polyethylene, or mechanically or chemically recycled polyethylene may be used.

In the second laminate of the present disclosure, the polyethylene constituting the extruded resin layer (sealant layer) is selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene from the viewpoint of low-temperature sealability. At least one type is preferred, low density polyethylene or linear low density polyethylene is more preferred, and linear low density polyethylene is particularly preferred. Biomass polyethylene, or mechanically or chemically recycled polyethylene may be used.

The melt flow rate (MFR) of the polyethylene that constitutes the extruded resin layer is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0, from the viewpoint of film-forming properties, processability of the laminate, and the like. 2 g/10 minutes or more and 30 g/10 minutes or less, more preferably 3.0 g/10 minutes or more and 20 g/10 minutes or less.

In the first laminate of the present disclosure, the melting point (Tm) of polyethylene constituting the extruded resin layer is preferably 100° C. or higher and 140° C. or lower, more preferably 100° C. or higher, from the viewpoint of the balance between heat resistance and adhesiveness. It is 130° C. or lower, more preferably 100° C. or higher and 120° C. or lower.

In the second laminate of the present disclosure, the melting point (Tm) of polyethylene constituting the extruded resin layer (sealant layer) is preferably 80° C. or higher and 130° C. or lower, more preferably 80° C. or higher, from the viewpoint of low-temperature sealing properties. It is 120° C. or lower, more preferably 90° C. or higher and 110° C. or lower. Further, in the second laminate of the present disclosure, the density of polyethylene constituting the extruded resin layer (sealant layer) is particularly preferably 0.900 g/cm ³ or more and 0.915 g/cm ³ or less.

The extruded resin layer can contain one or more polyethylenes.
The content of polyethylene in the extruded resin layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, the recyclability of the laminate can be improved.

The extruded resin layer contains biomass polyethylene in one embodiment. The biomass degree of the extruded resin layer in this case may be, for example, 30% or more, 50% or more, or 70% or more. Although the upper limit of the biomass degree is not particularly limited, it may be, for example, 99% or 98%.

In the first laminate of the present disclosure, the thickness of the extruded resin layer as the adhesive layer is preferably 5 μm or more and 40 μm or less, more preferably 10 μm or more and 30 μm or less. This can improve adhesion and recyclability, for example.

In the second laminate of the present disclosure, the thickness of the extruded resin layer as the sealant layer is preferably 15 μm or more and 60 μm or less, more preferably 20 μm or more and 50 μm or less. Thereby, for example, recyclability can be improved.

The extruded resin layer can be formed, for example, by melting polyethylene or a polyethylene resin composition and extruding it onto an oriented polyethylene substrate or a laminate comprising the substrate. The melting temperature at this time is, for example, 280° C. or higher and 340° C. or lower, preferably 290° C. or higher and 335° C. or lower.

In one embodiment of the present disclosure, as a method of bonding a stretched polyethylene base material or a laminate comprising the base material and a polyethylene film as a sealant layer, melt extrusion using a molten resin containing polyethylene as a main component is performed. A lamination method, in particular a sand lamination method, is used. Thereby, the polyethylene content ratio of the laminate can be increased. In addition, in the present disclosure, compared to laminating the stretched polyethylene base material or the laminate and the sealant layer, for example, by dry lamination, the time required for the drying process and the aging process can be reduced, thus improving the production efficiency of the laminate. can.

<Sealant layer>
A first laminate of the present disclosure comprises a polyethylene layer as a sealant layer.
A polyethylene layer contains polyethylene as a main component.
A polyethylene layer as a sealant layer is an unstretched layer (unstretched polyethylene layer) in one embodiment. An unstretched layer is a layer that has not been stretched, for example, an extruded film that has not been stretched. The details of the stretching process are as described above in the description of the base material.

Details of the polyethylene are as described above. The polyethylene in the sealant layer and the polyethylene in the oriented polyethylene substrate or the polyethylene in the extruded resin layer may be the same or different.

From the viewpoint of heat sealability, the polyethylene constituting the sealant layer is preferably at least one selected from low density polyethylene, linear low density polyethylene and ultra-low density polyethylene, more preferably linear low density polyethylene. . Biomass polyethylene, or mechanically or chemically recycled polyethylene may be used.

The melt flow rate (MFR) of the polyethylene constituting the sealant layer is preferably 0.1 g/10 minutes or more and 50 g/10 minutes or less, more preferably 0.1 g/10 minutes or more and 50 g/10 minutes or less, more preferably 0.1 g/10 minutes or more and 50 g/10 minutes or less, more preferably 0.1 g/10 minutes or more and 50 g/10 minutes or less. 2 g/10 minutes or more and 30 g/10 minutes or less, more preferably 0.3 g/10 minutes or more and 20 g/10 minutes or less.

The melting point (Tm) of polyethylene constituting the sealant layer is preferably 90° C. or higher and 140° C. or lower, more preferably 90° C. or higher and 130° C. or lower, still more preferably 90° C. or higher, from the viewpoint of the balance between heat resistance and heat sealability. 120° C. or less.

The sealant layer can contain one or more polyethylenes.
The content of polyethylene in the sealant layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, it is possible to improve the recyclability of the packaging material comprising the laminate of the present disclosure.

The sealant layer may contain one or more resin materials other than polyethylene. Examples of the resin material include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. When the sealant layer has a multilayer structure, each layer constituting the sealant layer can independently contain the resin material.

The sealant layer may contain one or more additives. Examples of additives include cross-linking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes and modifying resins. When the sealant layer has a multi-layer structure, each layer constituting the sealant layer can independently contain the above additives.

The sealant layer may have a single layer structure or a multilayer structure.
In one embodiment, the number of layers of the sealant layer having a multilayer structure is 2 or more and 7 or less, for example, 3 or more and 7 or less, or 3 or more and 5 or less. The number of layers of the sealant layer is preferably odd, for example 3, 5 or 7 layers. With such a configuration, for example, the symmetry of the lamination structure of the sealant layer is enhanced, and the occurrence of curling in the sealant layer can be suppressed.

In one embodiment, the sealant layer having a multilayer structure is a coextruded resin film, and each layer constituting the sealant layer is a coextruded resin layer. A co-extruded resin film can be produced by forming a film using, for example, an inflation method or a T-die method.

A sealant layer having a multilayer structure, in one embodiment, comprises a resin layer (1) and a resin layer (2). The resin layer (1) constitutes the surface layer of the sealant layer on the side opposite to the stretched polyethylene substrate side, and contains polyethylene as a main component. The resin layer (2) constitutes the surface layer of the sealant layer on the stretched polyethylene substrate side, and contains polyethylene as a main component. The sealant layer may further include an intermediate layer containing polyethylene as a main component between the resin layer (1) and the resin layer (2).

The polyethylene constituting the resin layer (1) is preferably at least one selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene from the viewpoint of heat sealability, and linear low-density polyethylene. is more preferred. Biomass polyethylene, or mechanically or chemically recycled polyethylene may be used.

The content of polyethylene in the resin layer (1) is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, the recyclability of the laminate can be improved.

The density of the resin layer (1) is preferably 0.920 g/cm ³ or less, more preferably 0.860 g/cm ³ or more and 0.920 g/cm ³ or less, and still more preferably 0.900 g/cm ³ or more and 0.918 g. / cm ³ or less.

The ratio of the thickness of the resin layer (1) to the total thickness of the sealant layer having a multilayer structure is preferably 2% or more and 40% or less, more preferably 5% or more and 35% or less, and still more preferably 10% or more and 30%. It is below.

In one embodiment, when a packaging container is produced using the packaging material comprising the laminate of the present disclosure, the resin layer (1) is a layer facing the content contained in the packaging container. Since the resin layer (1) has a density of 0.920 g/cm ³ or less, sufficient heat sealing strength can be obtained even when heat sealing is performed at a low temperature (for example, about 140° C.).

As polyethylene constituting the resin layer (2), at least one selected from low density polyethylene, linear low density polyethylene and ultra-low density polyethylene is preferable. Biomass polyethylene, or mechanically or chemically recycled polyethylene may be used.

The content of polyethylene in the resin layer (2) is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, the recyclability of the laminate can be improved.

The density of the resin layer (2) is preferably more than 0.900 g/cm ³ and less than 0.930 g/cm ³ , more preferably 0.905 g/cm ³ or more and less than 0.928 g/cm ³ , still more preferably 0 .910 g/cm ³ or more and less than 0.925 g/cm ³ . With such a configuration, for example, the symmetry of the density in the layer direction in the sealant layer having a multilayer structure can be increased, and the occurrence of curling in the sealant layer can be suppressed.

The ratio of the thickness of the resin layer (2) to the total thickness of the sealant layer having a multilayer structure is preferably 2% or more and 40% or less, more preferably 5% or more and 35% or less, and still more preferably 10% or more and 30%. It is below.

In the sealant layer having a multilayer structure, the difference (D2-D1) between the density D2 of the resin layer (2) and the density D1 of the resin layer (1) is preferably 0.020 g/cm ³ or less, more preferably 0. 0.015 g/cm ³ or less, more preferably 0.010 g/cm ³ or less. With such a configuration, the symmetry of the lamination structure of the sealant layer is enhanced, and for example, the occurrence of curling in the sealant layer can be suppressed.

The sealant layer having a multilayer structure may further include an intermediate layer containing polyethylene as a main component between the resin layer (1) and the resin layer (2). The number of layers of the intermediate layer may be one layer, two layers or more, and may be, for example, three layers or more and five layers or less.

At least one selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene is preferable as the polyethylene constituting the intermediate layer. Biomass polyethylene, or mechanically or chemically recycled polyethylene may be used.

The content of polyethylene in the intermediate layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. With such a configuration, for example, the recyclability of the laminate can be improved.

The ratio of the thickness of the intermediate layer to the total thickness of the sealant layer having a multilayer structure is preferably 20% or more and 96% or less, more preferably 30% or more and 90% or less, and still more preferably 40% or more and 80% or less. .

The total thickness of the sealant layer is preferably 10 μm to 300 μm, more preferably 15 μm to 250 μm, and in one embodiment 20 μm to 60 μm, or 40 μm to 200 μm. From the viewpoint of the strength and workability of the sealant layer, it is preferable to change the total thickness of the sealant layer as appropriate according to the mass of the contents contained in the packaging container described later.

For example, when the packaging container is a sachet, the total thickness of the sealant layer is preferably 20 µm or more and 60 µm or less. In this case, for example, 1 g or more and 200 g or less of contents can be well accommodated in the small bag. When the sealant layer is thin, if the oriented polyethylene base material and the sealant film are bonded together using a conventional non-polyethylene adhesive, the content of polyethylene in the entire laminate is greatly reduced. In the present disclosure, in one embodiment, the stretched polyethylene base material and the sealant film are bonded together by an extruded resin layer containing polyethylene as a main component, so the content of polyethylene can be increased.

For example, when the packaging container is a standing pouch, the total thickness of the sealant layer is preferably 40 μm or more and 200 μm or less, more preferably 60 μm or more and 150 μm or less. In this case, for example, contents of 50 g or more and 2000 g or less can be well accommodated in the standing pouch.

The sealant layer, in one embodiment, contains biomass polyethylene. In this case, the biomass degree of the sealant layer may be, for example, 10% or more, 10% or more and 80% or less, 20% or more and 75% or less, or 30% or more and 70% or less.

When the sealant layer has a multilayer structure, that is, when the sealant layer includes two or more resin layers containing polyethylene as a main component, at least one of the resin layers may contain biomass polyethylene.

For example, in the case of the sealant layer having the resin layer (1), the intermediate layer and the resin layer (2) in this order in the thickness direction, the resin layer (1), the intermediate layer and the resin layer (2) are selected. At least one layer may contain biomass polyethylene.

The laminate of the present disclosure may include a vapor deposition film formed on the stretched polyethylene substrate side surface of the sealant layer. Thereby, for example, the oxygen barrier property and water vapor barrier property of the laminate can be improved.

The details of the deposited film are as described above.
The surface of the deposited film may be subjected to the surface treatment described above. Thereby, for example, the adhesion between the deposited film and the layer adjacent to the deposited film can be improved.

[Use]
The laminate of the present disclosure can be suitably used for packaging material applications.
Packaging materials are used to make packaging containers. A packaging material comprises the laminate of the present disclosure. A packaging container can be produced by using at least a packaging material comprising the laminate of the present disclosure.

A packaging container comprises the laminate of the present disclosure. Packaging containers include, for example, packaging bags, tube containers, and containers with lids. A lidded container includes a container body having an accommodating portion, and a lid member joined (heat-sealed) to the container body so as to seal the accommodating portion.

Methods of heat sealing include, for example, bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing and ultrasonic sealing.

As packaging bags, for example, standing pouch type, side seal type, two side seal type, three side seal type, four side seal type, envelope pasted seal type, palm pasted seal type (pillow seal type), plaited seal type, flat bottom seal. There are various types of packaging bags such as type, square bottom seal type and gusset type.

The packaging bag may be provided with an easy-to-open portion. The easy-to-open portion includes, for example, a notch portion serving as a starting point for tearing the packaging bag, and a half-cut line formed by laser processing, a cutter, or the like as a path for tearing the packaging bag.

In one embodiment, the laminated body of the present disclosure is folded in half so that the stretched polyethylene base material is positioned outside and the sealant layer is positioned inside, and the ends and the like are heat-sealed to form a packaging bag. can be made. In another embodiment, a packaging bag can be produced by stacking a plurality of laminates of the present disclosure so that the sealant layers face each other and heat-sealing the edges and the like. The entire packaging bag may be composed of the laminate, or part of the packaging bag may be composed of the laminate.

In one embodiment, the laminate of the present disclosure is used as a lid material in a lidded container.

Contents contained in packaging containers include, for example, liquids, solids, powders, and gels. The contents may be food or drink, or may be non-food or drink such as chemicals, cosmetics, and pharmaceuticals. After containing the contents in the packaging container, the packaging container can be sealed by heat-sealing the opening of the packaging container.

As specific examples of packaging bags, small bags and standing pouches will be described below.
A sachet is a small packaging bag, and is used to contain, for example, 1 g or more and 200 g or less of contents. Contents contained in the sachet include, for example, sauces, soy sauce, dressings, ketchup, syrups, cooking liquors, other liquid or viscous seasonings; liquid soups, powdered soups, fruit juices; spices; Beverages, jellied beverages, ready-to-eat foods, and other food and drink.

Standing pouches are used, for example, to contain contents of 50 g or more and 2000 g or less. Contents contained in the standing pouch include, for example, shampoo, rinse, conditioner, hand soap, body soap, fragrance, deodorant, deodorant, insect repellent, detergent; dressing, edible oil, mayonnaise, and others. Liquid or viscous seasonings; liquid beverages, jelly-like beverages, instant foods, other foods and drinks; and creams.

FIG. 4 is a diagram simply showing an example of the configuration of a standing pouch. In the figure, the hatched portion represents the heat-sealed portion. As shown in FIG. 4, the standing pouch 40 in one embodiment comprises a body (side sheet) 41 and a bottom (bottom sheet) 42 . The side sheet 41 and the bottom sheet 42 may be composed of the same member or may be composed of different members. Since the bottom sheet retains the shape of the side sheets, the pouch can be made self-supporting and can be a standing pouch. A storage space for storing contents is formed in a region surrounded by the side sheet and the bottom sheet.

In the standing pouch, only the body may be composed of the laminate of the present disclosure, only the bottom may be composed of the laminate of the present disclosure, or both the body and the bottom may be composed of the laminate of the present disclosure. may

In one embodiment, the side sheets can be formed by preparing two laminates of the present disclosure, stacking them so that the sealant layers face each other, and heat-sealing the side edges on both sides to form a bag. .

In another embodiment, the side sheets are prepared by preparing two laminates of the present disclosure, overlapping them with the sealant layers facing each other, and separating the laminates at the side edges on both sides of the overlapped laminate. , two laminates folded in a V shape with the sealant layer on the outside are inserted and heat-sealed. Such a manufacturing method results in a standing pouch 40 having a body 41 with side gussets 43 as shown in FIG.

In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the bottoms of the bag-made side sheets and heat sealing. More specifically, the bottom sheet can be formed by inserting a laminate folded in a V-shape so that the sealant layer is on the outside between the lower parts of the bag-made side sheets, and heat-sealing.

In one embodiment, two laminates are prepared, these are superimposed so that the sealant layers face each other, and then another laminate is folded in a V shape so that the sealant layer is on the outside. , is sandwiched between the lower portions of the laminates facing each other and heat-sealed to form a bottom portion. The body is then formed by heat sealing the two sides adjacent to the bottom. In this manner, an embodiment standing pouch can be formed.

The present disclosure relates to, for example, the following [1] to [12].
[1] A laminate comprising a stretched polyethylene substrate and a sealant layer, wherein the stretched polyethylene substrate contains polyethylene as a main component, the sealant layer contains polyethylene as a main component, and the laminate comprises A laminate comprising an extruded resin layer containing polyethylene as a main component between an oriented polyethylene substrate and a sealant layer.
[2] The laminate according to [1] above, wherein the extruded resin layer contains at least one selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene as a main component.
[3] A laminate comprising a stretched polyethylene substrate and a sealant layer, wherein the stretched polyethylene substrate contains polyethylene as a main component, and the sealant layer is an extruded resin layer containing polyethylene as a main component. , laminate.
[4] The laminate according to [3] above, wherein the extruded resin layer contains linear low-density polyethylene as a main component.
[5] Any of the above [1] to [4], wherein the laminate further comprises an anchor coat layer between the stretched polyethylene substrate and the extruded resin layer, and the extruded resin layer is in contact with the anchor coat layer. The laminate according to any one of the above.
[6] The laminate according to any one of [1] to [5] above, wherein the oriented polyethylene base material is a uniaxially or biaxially oriented polyethylene base material.
[7] The laminate according to any one of [1] to [6] above, further comprising a printed layer on the sealant layer side surface of the stretched polyethylene base material.
[8] The laminate according to any one of [1] to [7] above, wherein the sealant layer has a thickness of 20 μm or more and 60 μm or less.
[9] The laminate according to any one of [1] to [8], wherein the polyethylene content is 90% by mass or more in 100% by mass of the laminate.
[10] The laminate according to any one of [1] to [9] above, which is used as a packaging material.
[11] A packaging material composed of the laminate according to any one of [1] to [10] above.
[12] A packaging container comprising the laminate according to any one of [1] to [10] above.

The laminate of the present disclosure will be described in more detail based on examples, but the laminate of the present disclosure is not limited by the examples.

In the following description, polyethylene film is also referred to as "PE film", high density polyethylene as "HDPE", medium density polyethylene as "MDPE", low density polyethylene as "LDPE", and linear low density polyethylene as "LLDPE". .
An anchor coating agent is also described as an “AC agent”.
An extruded resin layer of polyethylene is also referred to as "EC-PE."
An extruded resin layer of biomass polyethylene is also referred to as "EC-PEb".
Polyurethane adhesives are also described as "PU adhesives".

[Preparation of stretched PE substrate (base film)]
<Preparation of uniaxially stretched PE film (A)>
MDPE (density: 0.941 g/cm ³ , melting point: 129° C., MFR: 1.3 g/10 min, Dowchemical, trade name: Elite 5538G) was formed by an inflation molding method to obtain a PE film with a thickness of 125 μm. rice field. This PE film was stretched in the longitudinal direction (MD) at a draw ratio of 5 times to obtain a stretched PE film with a thickness of 25 μm. One side of this stretched PE film was subjected to corona treatment to adjust the wetting index to 52 dyn. The substrate thus obtained is also referred to as "uniaxially stretched PE film (A)". When the haze value of the uniaxially stretched PE film (A) was measured according to JIS K7136, it was 6.5%.

<Preparation of uniaxially stretched PE film (B)>
HDPE (density: 0.961 g/cm ³ , melting point: 135°C, MFR: 0.7 g/10 min, ExxonMobil, trade name: HTA108) and MDPE (density: 0.941 g/cm ³ , melting point: 129°C, MFR: 1.3 g/10 min, Dowchemical Co., trade name: Elite 5538G) was co-extruded into a film by an inflation molding method to obtain a PE film with a thickness of 125 μm consisting of an HDPE layer, an MDPE layer and an HDPE layer in that order. . The thickness of the HDPE layers was 25 μm each and the thickness of the MDPE layers was 75 μm. This PE film was stretched in the longitudinal direction (MD) at a draw ratio of 5 times to obtain a stretched PE film with a thickness of 25 µm. One side of this stretched PE film was subjected to corona treatment to adjust the wetting index to 52 dyn. The substrate thus obtained is also referred to as "uniaxially stretched PE film (B)". The haze value of the uniaxially stretched PE film (B) was 8.9%.

<Preparation of uniaxially stretched PE film (C)>
HDPE (density: 0.952 g/cm ³ , MFR: 2.0 g/10 minutes, biomass degree: 96%, Braskem, trade name: SGE7252) and MDPE (density: 0.941 g/cm ³ , melting point: 129°C , MFR: 1.3 g/10 min, Dowchemical Co., product name: Elite 5538G) was co-extruded into a film by an inflation molding method to obtain a PE film with a thickness of 125 μm consisting of an HDPE layer, an MDPE layer and an HDPE layer in that order. rice field. The thickness of the HDPE layers was 25 μm each and the thickness of the MDPE layers was 75 μm. This PE film was stretched in the longitudinal direction (MD) at a draw ratio of 5 times to obtain a stretched PE film with a thickness of 25 μm. One side of this stretched PE film was subjected to corona treatment to adjust the wetting index to 52 dyn. The substrate thus obtained is also referred to as "uniaxially stretched PE film (C)". The uniaxially stretched PE film (C) had a haze value of 10.9% and a biomass degree of 38%.

[Preparation of sealant film]
<Production of PE film (A)>
LDPE (density: 0.924 g/cm ³ , melting point: 111° C., MFR: 2.0 g/10 min, Ube Maruzen Polyethylene Co., Ltd., trade name: F224N) and plant-derived LDPE (density: 0.923 g/cm ³ , MFR: 2.7 g/10 minutes, biomass degree: 95%, Braskem, trade name: SEB853) and LLDPE (density: 0.916 g/cm ³ , melting point: 116°C, MFR: 2.3 g/10 Co., Ltd., Prime Polymer Co., Ltd., trade name: SP2020) is co-extruded into a film by an inflation molding method, and a 30 μm thick sealant film (hereinafter “PE Film (A)” was obtained. The thickness of each layer was LDPE layer: 6 μm, plant-derived LDPE layer: 18 μm, and LLDPE layer: 6 μm. The biomass degree was 57%.

[Example 1-1]
A uniaxially stretched PE film (A) and an unstretched LLDPE film (Mitsui Chemicals Tocello, TUX-TCS) having a thickness of 30 μm were prepared. The corona-treated surface of the uniaxially stretched PE film (A) was subjected to flexographic printing using an aqueous flexographic ink (Toyo Ink Co., Ltd., trade name: Aquariona) to form a 1 μm-thick printed layer. As an anchor coat agent, a two-liquid curable polyurethane adhesive (Mitsui Chemicals, Inc., A-3210/A-3075) was applied to the print layer forming surface to form an anchor coat layer having a thickness of 0.3 μm. Thus, a laminate consisting of the uniaxially stretched PE film (A), the printed layer and the anchor coat layer was obtained. LDPE (density: 0.918 g/cm ³ , melting point: 106° C., MFR: 7.0 g/10 min, Japan Polyethylene Co., Ltd., trade name: Novatec LC600A) was added to the anchor coat layer of the laminate as an extruded resin layer. The laminate and the unstretched LLDPE film were sand-laminated while melt extruding to a thickness of 15 μm. Thus, a laminate was obtained.

[Example 1-2]
A laminate was obtained in the same manner as in Example 1-1, except that the uniaxially stretched PE film (B) was used instead of the uniaxially stretched PE film (A).

[Example 1-3]
A laminate was obtained in the same manner as in Example 1-1 except that a 25 μm thick biaxially stretched PE film (JINDAL, trade name: 25HD-200) was used instead of the uniaxially stretched PE film (A). rice field.

[Example 1-4]
A uniaxially stretched PE film (B) was prepared. The corona-treated surface of the uniaxially stretched PE film (B) was subjected to flexographic printing using an aqueous flexographic ink (Toyo Ink Co., Ltd., trade name: Aquariona) to form a 1 μm-thick printed layer. As an anchor coat agent, a two-liquid curable polyurethane adhesive (Mitsui Chemicals, Inc., A-3210/A-3075) was applied to the print layer forming surface to form an anchor coat layer having a thickness of 0.3 μm. Thus, a laminate consisting of the uniaxially stretched PE film (B), the printed layer and the anchor coat layer was obtained. LLDPE (density: 0.906 g/cm ³ , melting point: 102° C., MFR: 10.5 g/10 min, Japan Polyethylene Co., Ltd., trade name: Kernel KC570S) was added to the anchor coat layer of the laminate as an extruded resin layer. The laminate was melt extruded to a thickness of 30 μm to obtain a laminate.

[Comparative Example 1-1]
A uniaxially stretched PE film (A) and an unstretched LLDPE film (Mitsui Chemicals Tocello, TUX-TCS) having a thickness of 30 μm were prepared. The corona-treated surface of the uniaxially stretched PE film (A) was subjected to flexographic printing using an aqueous flexographic ink (Toyo Ink Co., Ltd., trade name: Aquariona) to form a 1 μm-thick printed layer. Thus, a laminate consisting of the uniaxially stretched PE film (A) and the printed layer was obtained. An adhesive layer having a thickness of 4 μm made of a two-component curable polyurethane adhesive (RU-77T/H-7, manufactured by ROCK PAINT Co., Ltd.) was applied to the printed layer forming surface of the laminate and the corona-treated surface of the unstretched LLDPE film. A laminated body was obtained by laminating them together with each other.

[Comparative Example 1-2]
A laminate was obtained in the same manner as in Comparative Example 1-1, except that the uniaxially stretched PE film (B) was used instead of the uniaxially stretched PE film (A).

[Comparative Example 1-3]
A laminate was obtained in the same manner as in Comparative Example 1-1 except that a 25 μm thick biaxially stretched PE film (JINDAL, trade name: 25HD-200) was used instead of the uniaxially stretched PE film (A). rice field.

[Example 2-1]
Laminate in the same manner as in Example 1-1 except that the uniaxially stretched PE film (B) was used instead of the uniaxially stretched PE film (A) and the PE film (A) was used instead of the unstretched LLDPE film. got The PE film (A) was arranged so that its LLDPE layer was the outermost layer of the laminate. The biomass degree of the laminate was 24%.

[Example 2-2]
A uniaxially stretched PE film (B) is used instead of the uniaxially stretched PE film (A), and plant-derived LDPE (density: 0.918 g/cm ³ , MFR A laminate was obtained in the same manner as in Example 1-1, except that SBC818 (product name: 8.3 g/10 min, biomass degree: 95%, Braskem Co., Ltd.) was used. The biomass degree of the laminate was 20%.

[Example 2-3]
A laminate was obtained in the same manner as in Example 1-1, except that the uniaxially stretched PE film (C) was used instead of the uniaxially stretched PE film (A). The biomass degree of the laminate was 13.3%.

[Example 2-4]
Using the uniaxially stretched PE film (C) instead of the uniaxially stretched PE film (A), using the plant-derived LDPE (SBC818) instead of the LDPE (Novatec LC600A) as the forming resin for the extruded resin layer, and using the unstretched LLDPE film A laminate was obtained in the same manner as in Example 1-1, except that the PE film (A) was used instead. The PE film (A) was arranged so that its LLDPE layer was the outermost layer of the laminate. The biomass degree of the laminate was 57.3%.

[Comparative Example 2-1]
A uniaxially stretched PE film (B) and a PE film (A) were prepared. The corona-treated surface of the uniaxially stretched PE film (B) was subjected to flexographic printing using an aqueous flexographic ink (Toyo Ink Co., Ltd., trade name: Aquariona) to form a 1 μm-thick printed layer. Thus, a laminate consisting of the uniaxially stretched PE film (B) and the printed layer was obtained. The LDPE layer surface of the PE film (A) was subjected to corona treatment. The print layer forming surface of the laminate and the corona-treated surface of the PE film (A) were coated with an adhesive layer having a thickness of 4 μm made of a two-liquid curing polyurethane adhesive (RU-77T/H-7 manufactured by ROCK PAINT Co., Ltd.). A laminate was obtained by laminating together through. The biomass degree of the laminate was 28.5%.

[Comparative Example 2-2]
A laminate was obtained in the same manner as in Comparative Example 2-1 except that the uniaxially stretched PE film (C) was used instead of the uniaxially stretched PE film (B). The biomass degree of the laminate was 44.3%.

[Method for measuring seal strength]
Using two sheets of each of the laminates produced in Examples and Comparative Examples, the sealant layers of the laminate were heat-sealed under conditions of a temperature of 140° C., a pressure of 1 kgf/cm ² and a time of 1 second to form a sealed portion. Subsequently, a portion including the seal portion was cut out to prepare a test piece having a width of 15 mm and a length of 100 mm for measuring the seal strength. The length of the seal portion is 15 mm. The seal strength was measured at a test speed of 300 mm/min in accordance with JIS K7127:1999. As a measuring instrument, a tensile tester SA-1150 manufactured by Orientec Co., Ltd. was used.

1: Laminate 10: Stretched polyethylene base material 20: Extruded resin layer 22: Anchor coat layer 30: Sealant layer 40: Standing pouch 41: Body (side sheet)
42: Bottom (bottom sheet)
43: side gussets

Claims (12)

A laminate comprising an oriented polyethylene base material and a sealant layer,
The stretched polyethylene base material contains polyethylene as a main component,
The sealant layer contains polyethylene as a main component,
The laminate comprises an extruded resin layer containing polyethylene as a main component between the stretched polyethylene base material and the sealant layer,
laminate. 2. The laminate according to claim 1, wherein the extruded resin layer contains at least one selected from low density polyethylene, linear low density polyethylene and ultra-low density polyethylene as a main component. A laminate comprising an oriented polyethylene base material and a sealant layer,
The stretched polyethylene base material contains polyethylene as a main component,
The sealant layer is an extruded resin layer containing polyethylene as a main component,
laminate. The laminate according to claim 3, wherein the extruded resin layer contains linear low-density polyethylene as a main component. 5. The laminate further comprises an anchor coat layer between the stretched polyethylene base material and the extruded resin layer, and the extruded resin layer is in contact with the anchor coat layer. 1. Laminate according to item 1. The laminate according to any one of claims 1 to 5, wherein the oriented polyethylene base material is a uniaxially or biaxially oriented polyethylene base material. The laminate according to any one of claims 1 to 6, further comprising a printed layer on the surface of the stretched polyethylene substrate on the sealant layer side. The laminate according to any one of claims 1 to 7, wherein the sealant layer has a thickness of 20 µm or more and 60 µm or less. The laminate according to any one of claims 1 to 8, wherein the polyethylene content is 90% by mass or more in 100% by mass of the laminate. The laminate according to any one of claims 1 to 9, which is used as a packaging material. A packaging material composed of the laminate according to any one of claims 1 to 10. A packaging container comprising the laminate according to any one of claims 1 to 10.

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