Laminates, packaging materials, and packaging containers

Abstract

The objective is to improve the polyethylene content in a laminate comprising a stretchable substrate having a polyethylene substrate layer and a functional resin layer, and a polyethylene layer as a sealant layer. [Solution] A laminate comprising a stretched substrate and a sealant layer, wherein the stretched substrate comprises a substrate layer mainly containing polyethylene and a functional resin layer, the sealant layer mainly containing polyethylene, and the laminate comprises an extruded resin layer mainly containing polyethylene between the stretched substrate and the sealant layer.

Description

[Technical Field]

[0001] This disclosure relates to laminates, packaging materials, and packaging containers. [Background technology]

[0002] Film products are manufactured by laminating films of different materials together (for example, a polyester film as a base material and a polyethylene film as a sealant layer) to exhibit various functions (see, for example, Patent Document 1). Packaging containers are made from such film products. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2013-095454 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, addressing environmental issues such as plastic pollution in the oceans and global warming has become increasingly important. Therefore, packaging materials and other similar products require high recyclability. However, film products manufactured by laminating films of different materials are generally difficult to separate into their individual components, posing a challenge for recycling. To address this problem, a technology called monomaterialization is being explored, which involves manufacturing film products by laminating polyethylene films of the same material to improve recyclability.

[0005] The mono-materialization with polyethylene can be achieved by laminating polyethylene films with different properties, for example, by laminating a stretched polyethylene film as a base material and a polyethylene film as a sealant layer. However, when using a conventional non-polyethylene-based adhesive when laminating polyethylene films, the content ratio of polyethylene may decrease, which may cause a decrease in the physical properties of the recycled material. In addition, when a functional resin layer for imparting functions such as gas barrier properties is provided in the stretched polyethylene film, the content ratio of polyethylene further decreases.

[0006] One problem to be solved by the present disclosure is to improve the content ratio of polyethylene in a laminate including a stretched base material having a polyethylene base material layer and a functional resin layer, and a polyethylene layer as a sealant layer.

Means for Solving the Problem

[0007] The laminate of the present disclosure includes a stretched base material and a sealant layer, the stretched base material includes a base material layer containing polyethylene as a main component and a functional resin layer, the sealant layer contains polyethylene as a main component, and the laminate includes an extruded resin layer containing polyethylene as a main component between the stretched base material and the sealant layer.

Effect of the Invention

[0008] According to the present disclosure, the content ratio of polyethylene in a laminate including a stretched base material having a polyethylene base material layer and a functional resin layer, and a polyethylene layer as a sealant layer can be improved. Since the laminate of the present disclosure includes an extruded resin layer containing polyethylene as a main component between the stretched base material and the sealant layer, for example, while using a stretched base material having a functional resin layer, the content ratio of polyethylene can be increased.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of an embodiment of the laminate of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. [Figure 3] Figure 3 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. [Figure 4] Figure 4 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. [Figure 5] Figure 5 is a schematic cross-sectional view of one embodiment of the laminate of the present disclosure. [Figure 6] Figure 6 is a perspective view of one embodiment of a standing pouch. [Figure 7] Figure 7 is a perspective view of one embodiment of a standing pouch. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below. This disclosure can be implemented in many different forms and is not construed as being limited to the embodiments described below. The drawings may schematically represent the width, thickness, and shape of each layer, etc., compared to the embodiments, in order to clarify the explanation, but these are merely examples and do not limit the interpretation of this disclosure. In this specification and in each figure, elements similar to those already described in the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0011] [Laminated structure] The laminate of the present disclosure comprises a stretched substrate having a base layer and a functional resin layer, and a polyethylene layer as a sealant layer. The laminate of the present disclosure comprises an extruded resin layer mainly containing polyethylene between the stretched substrate and the sealant layer.

[0012] In one embodiment of the laminate of this disclosure, the base material layer and the sealant layer in the stretched base material 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 manufactured.

[0013] In this disclosure, the phrase "AAA contains polyethylene as its main component," "AAA containing polyethylene as its main component," or similar statements mean that the polyethylene content in the AAA is more than 50% by mass, preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0014] For example, polyethylene includes high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene, all of which are classified as the same type of resin material. On the other hand, polyethylene and polyester, for example, are not classified as the same type of resin material.

[0015] In this disclosure, polyethylene refers to a polymer in which the content of ethylene-derived structural units is 50 mol% or more of the total 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, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. The above content can be measured by NMR spectroscopy.

[0016] In this 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 α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene; vinyl monomers such as vinyl acetate and vinyl propionate; and (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate.

[0017] In the present disclosure, examples of the polyethylene include high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, and ultra-low density polyethylene.

[0018] In the present disclosure, the density of the above polyethylene is as follows. The density of high density polyethylene is preferably 0.945 g / cm 3 or more. The upper limit of the density of high density polyethylene is, for example, 0.965 g / cm 3 or less. 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 low density polyethylene is preferably 0.900 g / cm 3 or more and less than 0.925 g / cm 3 The density of linear low density polyethylene is preferably 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 / cm 3 The lower limit of the density of ultra-low density polyethylene is, for example, 0.860 g / cm 3 or more. The density of polyethylene is measured in accordance with JIS K7112, particularly the D method (density gradient column method, 23 °C).

[0019] 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 (for example, a polymerization method using a Ziegler-Natta catalyst or a metallocene catalyst).

[0020] Polyethylenes having different densities or degrees of branching can be obtained by appropriately selecting the polymerization method. For example, as the polymerization catalyst, a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst is used, and polymerization is preferably carried out in one or two or more stages by any of gas phase polymerization, slurry polymerization, solution polymerization, and high pressure ionic polymerization methods.

[0021] A single-site catalyst is a catalyst capable of forming a uniform active species, and is usually prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activation co-catalyst. Compared to multi-site catalysts, single-site catalysts are preferred because they have a more uniform active site structure, allowing for the production of polymers with high molecular weight and high uniformity.

[0022] As a single-site catalyst, a metallocene catalyst is preferred. The metallocene catalyst is a catalyst comprising a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a co-catalyst, an organometallic compound if necessary, and a support if necessary.

[0023] Examples of transition metals in transition metal compounds include zirconium, titanium, and hafnium, with zirconium and hafnium being preferred.

[0024] In transition metal compounds, the cyclopentadienyl skeleton is a cyclopentadienyl group or a substituted cyclopentadienyl group. A substituted cyclopentadienyl group has at least one substituent selected from, for example, a hydrocarbon group having 1 to 30 carbon atoms, a silyl group, a silyl-substituted alkyl group, a silyl-substituted aryl group, a cyano group, a cyanoalkyl group, a cyanoaryl group, a halogen group, a haloalkyl group, and a halosilyl group. A substituted cyclopentadienyl group has one or more substituents, and the substituents may bond to each other to form a ring, which may form an indenyl ring, a fluorenyl ring, an azlenyl ring, or a hydrogenated version thereof. The ring formed by the bonding of substituents may further have substituents.

[0025] Transition metal compounds typically have two ligands having a cyclopentadienyl skeleton. Preferably, each ligand having a cyclopentadienyl skeleton is bonded to one another by a bridging group. Examples of bridging groups include alkylene groups having 1 to 4 carbon atoms, silylene groups, substituted silylene groups such as dialkylsilylene groups and diarylsilylene groups, and substituted germylene groups such as dialkylgermylene groups and diarylgermylene groups. Among these, substituted silylene groups are preferred.

[0026] A co-catalyst is a component that can effectively enable transition metal compounds of Group IV of the periodic table to function as polymerization catalysts, or a component that can balance the ionic charge in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes or benzene-insoluble organoaluminum oxy compounds, ion-exchangeable layered silicates, boron compounds, ionic compounds consisting 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.

[0027] Examples of organometallic compounds that may be used as needed include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Among these, organoaluminum compounds are preferred.

[0028] Transition metal compounds may be used supported on an inorganic or organic compound. Preferred supports are porous oxides of inorganic or organic compounds, specifically ion-exchangeable layered silicates such as montmorillonite, SiO2, Al2O3, MgO, ZrO2, TiO2, B2O3, CaO, ZnO, BaO, ThO2, or mixtures thereof.

[0029] In this disclosure, polyethylene derived from biomass (hereinafter also referred to as "biomass polyethylene") may be used as polyethylene. That is, instead of ethylene obtained from fossil fuels, biomass-derived ethylene may be used as a raw material for obtaining polyethylene. Since biomass polyethylene is a carbon-neutral material, it can reduce the environmental burden of laminates or packaging materials. Biomass polyethylene can be produced, for example, by the method described in Japanese Patent Application Publication No. 2013-177531. Commercially available biomass polyethylene may also be used.

[0030] Biomass-derived ethylene, which is a raw material for biomass polyethylene, can be obtained by conventionally known methods. An example of a method for producing biomass-derived ethylene is described below.

[0031] 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 materials. Conventional known plants can be used as plant materials, such as corn, sugarcane, beet, and manioc.

[0032] Biomass-derived fermented ethanol refers to ethanol produced by contacting a culture medium containing a carbon source obtained from plant raw materials with microorganisms that produce ethanol or products derived from their crushed material, and then purifying the ethanol. Conventional methods known as distillation, membrane separation, and extraction can be applied to purify the ethanol from the culture medium. For example, methods include adding benzene, cyclohexane, etc., and azeotropic distillation, or removing water by membrane separation, etc. To obtain the above-mentioned ethylene, further advanced purification may be performed at this stage, such as reducing the total amount of impurities in the ethanol to 1 ppm or less.

[0033] A catalyst is usually used when obtaining ethylene by the dehydration reaction of ethanol. Conventionally known catalysts can be used. A reaction mode that is advantageous from a process perspective is a fixed-bed flow reaction, which allows for easy separation of the catalyst and the product. For example, γ-alumina is preferred.

[0034] Since this dehydration reaction is an endothermic reaction, it is usually carried out under heating conditions. The heating temperature is not limited as long as the reaction proceeds at a commercially useful rate, but a temperature of 100°C or higher is preferable, more preferably 250°C or higher, and even more preferably 300°C or higher. There is no particular upper limit, but from the viewpoint of energy balance and equipment, it is preferable to have a temperature of 500°C or lower, more preferably 400°C or lower.

[0035] In the dehydration reaction of ethanol, the yield of the reaction depends on the amount of water contained in the ethanol supplied as a raw material. Generally, when performing a dehydration reaction, it is preferable to have no water present in order to improve the efficiency of water removal. However, in the case of the dehydration reaction of ethanol using a solid catalyst, the amount of other olefins, especially butene, tends to increase when water is absent. This is presumably because the dimerization of ethylene after dehydration cannot be suppressed without a small amount of water. The water content is, for example, 0.1% by mass or more, preferably 0.5% by mass or more. From the viewpoint of mass balance and heat balance, the water content is, for example, 50% by mass or less, preferably 30% by mass or less, and more preferably 20% by mass or less.

[0036] By carrying out the dehydration reaction of ethanol in this manner, a mixture of ethylene, water, and a small amount of unreacted ethanol is obtained. Since ethylene is a gas at room temperature and below approximately 5 MPa, water and ethanol can be removed from this mixture by gas-liquid separation to obtain ethylene. This can be done by known methods.

[0037] The ethylene obtained by gas-liquid separation is further distilled, and there are no particular restrictions on the distillation method, operating temperature, residence time, etc., except that the operating pressure at this time is above atmospheric pressure.

[0038] When the raw material is biomass-derived ethanol, the resulting ethylene contains trace amounts of impurities introduced during the ethanol fermentation process, such as carbonyl compounds like ketones, aldehydes, and esters, as well as their decomposition products like carbon dioxide, and nitrogen-containing compounds like amines and amino acids, as well as their decomposition products like ammonia. Depending on the intended use of the ethylene, these trace amounts of impurities may be problematic and may be removed by purification. Purification can be carried out by conventionally known methods. A suitable purification method is, for example, adsorption purification. Conventionally known adsorbents can be used as the adsorbent. For example, materials with a high surface area are preferred, and the type of adsorbent is selected according to the type and amount of impurities in the ethylene obtained by the dehydration reaction of biomass-derived ethanol.

[0039] As a method for purifying impurities in ethylene, caustic water treatment may be used in combination. If caustic water treatment is used, it is desirable to perform it before adsorption purification. In that case, it is necessary to perform a water removal treatment after the caustic treatment and before adsorption purification.

[0040] Biomass polyethylene is polyethylene obtained by polymerizing monomers containing ethylene derived from biomass. Preferably, the ethylene obtained by the above manufacturing method is used as the biomass-derived ethylene. Since biomass-derived ethylene is used as the raw material monomer, the polymerized polyethylene is biomass-derived.

[0041] The raw material monomers for biomass polyethylene do not necessarily have to contain 100% by mass of biomass-derived ethylene. The raw material monomers for biomass polyethylene may also contain ethylene derived from fossil fuels in addition to biomass-derived ethylene.

[0042] Atmospheric carbon dioxide contains a certain proportion (105.5 pMC) of C14, and it is known that the C14 content of plants that grow by taking in atmospheric carbon dioxide, such as corn, is also around 105.5 pMC. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the proportion of C14 contained in the total number of carbon atoms, the proportion of carbon derived from biomass can be calculated. In this disclosure, "biomass degree" refers to the weight ratio of biomass-derived components. For example, let's take polyethylene terephthalate as an 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 biomass-derived components in the polyester is 31.25%. Therefore, the theoretical value of the biomass degree is 31.25%. Specifically, the mass of polyethylene terephthalate is 192, of which 60 is derived from biomass-derived ethylene glycol. Therefore, 60 ÷ 192 × 100 = 31.25. The weight ratio of biomass-derived components in fossil fuel-derived polyester produced using fossil fuel-derived ethylene glycol and fossil fuel-derived dicarboxylic acid is 0%, and the biomass content of fossil fuel-derived polyester is 0%. Hereafter, unless otherwise specified, "biomass content" refers to the weight ratio of biomass-derived components.

[0043] Theoretically, if all ethylene is derived from biomass as the raw material for polyethylene, the biomass-derived ethylene concentration will be 100%, and the biomass content of biomass polyethylene will be 100%. In fossil fuel polyethylene, which is produced using only fossil fuel-derived raw materials, the biomass-derived ethylene concentration is 0%, and the biomass content of fossil fuel polyethylene is 0%.

[0044] Examples of biomass polyethylene include, for example, biomass high-density polyethylene, biomass medium-density polyethylene, biomass low-density polyethylene, biomass linear low-density polyethylene, and biomass ultra-low-density polyethylene. In one embodiment, the biomass content of the biomass polyethylene is 80% or more, 85% or more, 90% or more, or 95% or more. As for biomass polyethylene, plant-derived polyethylene is preferred.

[0045] In this disclosure, the biomass polyethylene and biomass-derived resin layers do not need to be 100% biomass. This is because if even a portion of the laminate is made from biomass-derived raw materials, it is in line with the purpose of reducing the amount of fossil fuels used compared to conventional methods.

[0046] The biomass content of the laminate in this disclosure may be, for example, 5% to 70%, 8% to 40%, or 10% to 30%. This can reduce the environmental burden caused by the laminate or packaging material, for example.

[0047] As polyethylene, polyethylene recycled by mechanical recycling or chemical recycling may be used. This reduces the environmental burden of laminates or packaging materials. Mechanical recycling generally involves crushing collected polyethylene film, washing it with alkali to remove dirt and foreign matter from the film surface, drying it at high temperature and reduced pressure for a certain period of time to disperse contaminants remaining inside the film and decontaminate it, removing the dirt from the film and returning it to polyethylene. Chemical recycling generally involves decomposing collected polyethylene film down to the monomer level and then repolymerizing the monomers to obtain polyethylene. The above description of polyethylene applies to the polyethylene described below.

[0048] The polyethylene content in the entire laminate of this disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. In this disclosure, as will be described later, an extruded resin layer containing polyethylene as the main component is used as the adhesive layer, so the polyethylene content can be increased. Since such a laminate uses polyethylene, which is the same type of resin material, it can be classified as a so-called monomaterial material and can be suitably used, for example, in the manufacture of monomaterial packaging containers.

[0049] Figures 1 and 2 show one embodiment of the laminate of the present disclosure. The laminate 1 in Figure 1 comprises a stretched substrate 10 having a base layer 12, an adhesive resin layer 14, and a functional resin layer 16, an extruded resin layer 20, and a sealant layer 30 in this order in the thickness direction. The laminate 1 in Figure 2 further comprises an anchor coat layer 22 between the stretched substrate 10 and the extruded resin layer 20. The extruded resin layer 20 is in contact with the anchor coat layer 22.

[0050] Figures 3, 4, and 5 show one embodiment of the laminate of the present disclosure. The laminate 1 in Figure 3 further comprises a vapor-deposited film 18 between the stretched substrate 10 and the extruded resin layer 20. The laminate 1 in Figure 4 further comprises a vapor-deposited film 18 between the stretched substrate 10 and the anchor coat layer 22. The vapor-deposited film 18 is formed on the surface of the functional resin layer 16 of the stretched substrate 10. The laminate 1 in Figure 5 further comprises a barrier coat layer 19 between the vapor-deposited film 18 and the anchor coat layer 22.

[0051] Figures 1 to 5 show an embodiment in which the stretched substrate 10 comprises a substrate layer 12, an adhesive resin layer 14, and a functional resin layer 16. However, an embodiment in which the adhesive resin layer 14 is not provided is also possible.

[0052] If the functional resin layer is a heat-resistant resin layer, such as a polyamide resin layer, the stretched substrate may be arranged such that the functional resin layer is the outermost layer of the laminate (for example, as in the embodiments of Figures 1 and 2, when no vapor-deposited film is provided on the surface of the stretched substrate). For example, in the case of Figure 1, the laminate 1 may have a functional resin layer 16, an adhesive resin layer 14, a substrate layer 12, an extruded resin layer 20, and a sealant layer 30 arranged in this order in the thickness direction. Therefore, in one embodiment, the heat-resistant resin layer may constitute the surface layer of the laminate of this disclosure.

[0053] In one embodiment, the laminate 1 further comprises a printed layer (not shown) on the stretched substrate 10. The printed layer is formed, for example, on the surface of the stretched substrate 10 that faces the sealant layer 30. The printed layer is located, for example, between the stretched substrate 10 (or the vapor-deposited film 18 or barrier coat layer 19 if one is provided) and the extruded resin layer 20 (or the anchor coat layer 22 if one is provided).

[0054] <Stretched base material> The stretched substrate is A base layer containing polyethylene as the main component, If necessary, an adhesive resin layer and Functional resin layer and These are arranged in this order in the thickness direction.

[0055] The stretched substrate is obtained by stretching. Stretching improves the transparency, rigidity, strength, and heat resistance of the substrate, making it suitable for use as a base material for packaging materials, for example. Stretching can also be performed in conjunction with an inflation film-forming machine.

[0056] The stretching of the stretched substrate may be uniaxial or biaxial. In one embodiment, the stretching ratio in the longitudinal direction (MD) of the stretched substrate is preferably 2 to 10 times, more preferably 3 to 7 times. In one embodiment, the stretching ratio in the transverse direction (TD) of the stretched substrate is preferably 2 to 10 times, more preferably 3 to 7 times.

[0057] If the stretching 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 stretching ratio is 10 times or less, for example, good stretching can be performed without causing the film to break.

[0058] In one embodiment, the stretched substrate is a uniaxially oriented film, and more specifically, a uniaxially oriented film that has been stretched in the longitudinal direction (MD).

[0059] The haze value of the stretched substrate is preferably 25% or less, more preferably 15% or less, and even more preferably 12% or less. A smaller haze value is preferable, but in one embodiment, the lower limit may be 0.1% or 1%. The haze value of the substrate is measured in accordance with JIS K7136.

[0060] The thickness of the stretched substrate is preferably 10 μm to 60 μm, more preferably 15 μm to 50 μm. A substrate thickness of 10 μm or more improves the rigidity and strength of the laminate. A substrate thickness of 60 μm or less improves the processability of the laminate.

[0061] The stretched substrate may be surface-treated. This can improve, for example, the adhesion between the substrate and the layer laminated on it. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using gases such as oxygen and nitrogen, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals. An anchor coat layer may be formed on the surface of the stretched substrate using a conventionally known anchor coat agent.

[0062] In one embodiment, the stretched substrate is a co-extruded resin film, and each layer constituting the stretched substrate is a co-extruded resin layer. The co-extruded resin film can be produced, for example, by forming the materials constituting each layer using an inflation method or a T-die method, and then stretching the film. This allows for the formation of, for example, a thin functional resin layer. In one embodiment, the stretched substrate is obtained by stretching a resin film obtained by co-extruding the materials constituting the substrate layer, the materials constituting the adhesive resin layer if the stretched substrate includes an adhesive resin layer, and the materials constituting the functional resin layer using a conventionally known method such as a T-die method or an inflation method.

[0063] In the laminate of this disclosure, the polyethylene content in the stretched substrate is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 90% by mass or less. With such a configuration, for example, the recyclability of the laminate can be improved.

[0064] (base material layer) The base layer contains polyethylene as its main component. Because the resin material constituting the base layer is polyethylene, which is the same type of resin material as the resin material constituting the sealant layer, a laminate having such a configuration can be suitably used as a laminate for manufacturing monomaterial packaging containers.

[0065] From the viewpoint of the strength and heat resistance of the stretchable substrate, high-density polyethylene and medium-density polyethylene are preferred, and from the viewpoint of stretchability, medium-density polyethylene is preferred.

[0066] The melt flow rate (MFR) of the polyethylene constituting the base layer is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, even more preferably 0.2 g / 10 min to 10 g / 10 min, and particularly preferably 0.2 g / 10 min to 5.0 g / 10 min, from the viewpoint of film-forming properties and the processability of the laminate. The MFR of polyethylene is measured by Method A in accordance with JIS K7210, under conditions of a temperature of 190°C and a load of 2.16 kg.

[0067] For example, when manufacturing a stretched substrate by the T-die method, the MFR of the polyethylene constituting the substrate layer is preferably 3.0 g / 10 min or more and 20 g / 10 min or less, from the viewpoint of film-forming properties and processability.

[0068] For example, when manufacturing a stretched substrate by the inflation method, the MFR of the polyethylene constituting the substrate layer is preferably 0.2 g / 10 min or more and 5.0 g / 10 min or less, from the viewpoint of film-forming properties and processability.

[0069] The melting point (Tm) of the polyethylene constituting the base layer is preferably 100°C to 140°C, more preferably 110°C to 140°C, and even more preferably 120°C to 140°C, from the viewpoint of heat resistance. Tm is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0070] The base layer may contain one or more types of polyethylene. The polyethylene content in the base layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. This configuration can improve, for example, the recyclability of the laminate.

[0071] When the base layer has a multilayer structure, the polyethylene content in each layer constituting the base layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, independently of each other. With such a configuration, for example, the recyclability of the laminate can be improved.

[0072] The base layer may contain one or more resin materials other than polyethylene. Examples of such resin materials include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. If the base layer has a multilayer structure, each layer constituting the base layer may independently contain one of the above resin materials.

[0073] The base layer may contain one or more additives. Examples of additives include crosslinking agents, antiblocking agents, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins. If the base layer has a multilayer structure, each layer constituting the base layer may independently contain the above additives.

[0074] The base layer is a stretched polyethylene layer. Stretching can improve, for example, the heat resistance and strength of the polyethylene layer. Such a base layer can satisfy the physical properties required for, for example, an outer layer of a packaging material. In one embodiment, the substrate layer constitutes the surface layer of the laminate of the present disclosure.

[0075] The base material layer may have a single-layer structure or a multi-layer structure. Hereinafter, a base material layer having a multi-layer structure will also be referred to as a "stretched multi-layer base material." Stretched multi-layer base materials are preferred from the viewpoint of improving their strength, heat resistance, and stretchability.

[0076] The 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 two to seven, for example, three to seven, or three to five. The number of layers of the stretched multilayer substrate is preferably an odd number, for example, three, five, or seven. The stretched multilayer substrate has a multilayer structure, which improves the balance of the substrate's rigidity, strength, heat resistance, printability, and stretchability. It is also preferable that each layer of the stretched multilayer substrate contains polyethylene as its main component.

[0077] Below, several examples of embodiments of the stretched multilayer substrate will be described. Hereinafter, a layer with a high-density polyethylene content of 80% by mass or more will be referred to as the "high-density polyethylene layer," a layer with a medium-density polyethylene content of 80% by mass or more will be referred to as the "medium-density polyethylene layer," a layer with a low-density polyethylene content of 80% by mass or more will be referred to as the "low-density polyethylene layer," a layer with a linear low-density polyethylene content of 80% by mass or more will be referred to as the "linear low-density polyethylene layer," and a layer with an ultra-low-density polyethylene content of 80% by mass or more will be referred to as the "ultra-low-density polyethylene layer."

[0078] The stretched multilayer substrate of the first embodiment comprises a high-density polyethylene layer and a medium-density polyethylene layer in this order in the thickness direction. Having a high-density polyethylene layer as the surface resin layer of the substrate improves, for example, the strength and heat resistance of the substrate. Having a medium-density polyethylene layer in the substrate improves, for example, the stretchability of the pre-stretched laminate.

[0079] The stretched multilayer substrate of the second embodiment comprises a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer in this order in the thickness direction. With this configuration, for example, the strength and heat resistance of the substrate can be improved, the occurrence of curl in the substrate can be suppressed, and the stretchability of the pre-stretched laminate can be improved.

[0080] In the stretched multilayer substrates of the first and second embodiments, the thickness of the high-density polyethylene layer is preferably less than or equal to 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.

[0081] The stretched multilayer substrate of the third embodiment comprises 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 the sake of simplicity, these three layers are collectively referred to as "low-density polyethylene layer, etc."), a medium-density polyethylene layer, and a high-density polyethylene layer, in this order in the thickness direction. By having such a configuration, for example, the stretchability of the pre-stretched laminate can be improved, the strength and heat resistance of the substrate can be improved, and the occurrence of curl in the substrate can be suppressed.

[0082] In the stretched multilayer substrate of the third embodiment, the thickness of the high-density polyethylene layer is preferably less than or equal to 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.

[0083] In the stretched multilayer substrate 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, etc. The ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer, etc. (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.

[0084] Other embodiments of stretched multilayer substrates include a substrate comprising 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 in this order in the thickness direction; and a substrate comprising 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.

[0085] Another example is a substrate comprising a high-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, a low-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, and a high-density polyethylene layer, in this order in the thickness direction.

[0086] The stretched multilayer substrate of the fourth embodiment comprises a medium-density polyethylene layer, a high-density polyethylene layer, a blended layer of medium-density polyethylene and high-density polyethylene, a high-density polyethylene layer, and a medium-density polyethylene layer, in this order in the thickness direction. With this 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-stretched laminate can be improved.

[0087] In the above-mentioned 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 or more and 2.4 or less.

[0088] The stretched multilayer substrate of the fifth embodiment comprises, in the thickness direction, 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. With this 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-stretched laminate can be improved.

[0089] In the above-mentioned 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 and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0090] The stretched multilayer substrate of the sixth embodiment comprises, in the thickness direction, 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, a blend layer of medium-density polyethylene and linear low-density polyethylene, and a blend layer of medium-density polyethylene and high-density polyethylene. With this 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-stretched laminate can be improved.

[0091] In the above-mentioned 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, and more preferably 0.4 or more and 2.4 or less, for each.

[0092] In the above-mentioned 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 and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0093] The stretched multilayer substrate of the seventh embodiment comprises, in the thickness direction, 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, a medium-density polyethylene layer, and a blend layer of high-density polyethylene and medium-density polyethylene. With this 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-stretched laminate can be improved.

[0094] In the above-mentioned blend layer of high-density polyethylene and medium-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 or more and 2.4 or less, for each individual.

[0095] In the blend layer of linear low-density polyethylene and medium-density polyethylene, the mass ratio of linear low-density polyethylene to medium-density polyethylene (linear low-density polyethylene / medium-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0096] The stretched multilayer substrate of the eighth embodiment comprises, in the thickness direction, a first layer containing medium-density polyethylene and high-density polyethylene, a second layer containing high-density polyethylene, a third layer containing linear low-density polyethylene, a fourth layer containing high-density polyethylene, and a fifth layer containing medium-density polyethylene and high-density polyethylene, in this order.

[0097] The mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) in the first and fifth layers is preferably 1.1 to 5, and more preferably 1.5 to 3, independently of each other. This further improves the balance between ink adhesion and heat resistance.

[0098] The total content of medium-density polyethylene and high-density polyethylene in the first and fifth layers is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, respectively. This further improves the ink adhesion and heat resistance of the substrate.

[0099] The second and fourth layers may each independently further contain low-density polyethylene. This can further improve the balance of heat resistance, rigidity, and processability of the substrate.

[0100] The mass ratio of high-density polyethylene to low-density polyethylene (high-density polyethylene / low-density polyethylene) in the second and fourth layers is preferably 1 to 4, and more preferably 1.5 to 3, independently of each other. This further improves the balance of heat resistance, rigidity, and processability of the base material.

[0101] The content of high-density polyethylene in the second and fourth layers is preferably more than 50% by mass, more preferably 55% by mass or more, and even more preferably 60% by mass or more, independently of each other. This further improves the heat resistance of the substrate.

[0102] The total content of high-density polyethylene and low-density polyethylene in the second and fourth layers is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, respectively. This further improves the balance of heat resistance, rigidity, and processability of the base material.

[0103] The thickness of the second and fourth layers is preferably 0.5 μm to 15 μm, more preferably 1 μm to 10 μm, and even more preferably 1 μm to 8 μm, respectively. This further improves the heat resistance of the substrate.

[0104] The third layer may further contain low-density polyethylene.

[0105] 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, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, 90% by mass or more, or 95% by mass or more. This allows for a further improvement in the balance of heat resistance, rigidity, and stretchability.

[0106] 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 even more preferably 10% to 30% by mass.

[0107] The thickness of the third layer is preferably 1 μm to 50 μm, more preferably 2 μm to 40 μm, and even more preferably 5 μm to 30 μm. This allows for a further improvement in the balance of heat resistance, rigidity, and stretchability.

[0108] The ratio of the total thickness of the second and fourth layers to the thickness of the third layer (total thickness of the second and fourth layers / thickness of the third layer) is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.5 to 2. This further improves the rigidity, strength, and heat resistance of the substrate.

[0109] 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 to 10 μm, more preferably 1 μm to 8 μm, and even more preferably 1 μm to 5 μm, independently of each other. This allows for further improvement of, for example, the heat resistance and printability of the substrate.

[0110] In the stretched multilayer substrates of the fourth to eighth embodiments, it is preferable that the thickness of each of the two surface resin layers is smaller than the total thickness of the three inner layers (multilayer intermediate layers). The ratio of the thickness of each of the two surface resin layers to the total thickness of the multilayer intermediate layers (surface resin layer / multilayer intermediate layer) is preferably 0.05 or more and 0.8 or less, more preferably 0.1 or more and 0.7 or less, and even more preferably 0.1 or more and 0.4 or less. This allows for further improvement of the rigidity, strength, and heat resistance of the substrate, for example.

[0111] In a stretched multilayer substrate, the density of the polyethylene constituting each layer may be the same or different. For example, the stretched multilayer substrate may have a density gradient in each layer. By providing a density gradient in the stretched multilayer substrate, its strength, heat resistance, and stretchability can be improved, for example.

[0112] In a stretched multilayer substrate having a density gradient, it is preferable that the absolute value of the density difference between any two adjacent layers is small. The absolute value of the above density difference is preferably 0.040 g / cm³. 3 More preferably, 0.030 g / cm³ 3 More preferably, 0.020 g / cm³ 3 The following is the result. With this configuration, for example, the occurrence of delamination at the interface of each layer can be effectively suppressed.

[0113] In this disclosure, the density of each layer may be measured in accordance with the above JIS K7112, or it may be calculated from the density of the components constituting the layer. For example, if a single layer contains multiple types (n types; n is an integer of 2 or more) of components with different densities (e.g., polyethylene), the average density D is calculated according to the following formula (f1). av This may be used as the density of the layer.

[0114] D av = ΣW i ×D i …(f1) In equation (f1), Σ represents W from 1 to n for i. i ×D i This means taking the sum of n, where n is an integer greater than or equal to 2, and W i This indicates the mass fraction of the i-th component, and D i This is the density of the i-th component (g / cm³). 3 ) indicates.

[0115] In one embodiment, the base layer contains biomass polyethylene. In this case, the biomass content of the base layer may be, for example, 10% or more, 10% to 65%, 20% to 55%, or 25% to 50%.

[0116] If the base layer has a multilayer structure, that is, if the base layer comprises two or more resin layers mainly composed of polyethylene, at least one of the resin layers may contain biomass polyethylene.

[0117] For example, a base layer comprising a first resin layer mainly containing high-density polyethylene, a second resin layer mainly containing medium-density polyethylene, and a third resin layer mainly containing high-density polyethylene, in this order in the thickness direction, will be described. In this case, at least one selected from the high-density polyethylene in the first resin layer, the medium-density polyethylene in the second resin layer, and the high-density polyethylene in the third resin layer may be biomass polyethylene.

[0118] The thickness of the base layer is preferably 5 μm to 55 μm, more preferably 10 μm to 45 μm. If the thickness is above the lower limit, for example, the rigidity and strength of the laminate can be improved. If the thickness is below the upper limit, for example, the processability of the laminate can be improved.

[0119] (adhesive resin layer) The stretched substrate may include an adhesive resin layer between the substrate layer and the functional resin layer. This can improve, for example, the adhesion between the substrate layer and the functional resin layer.

[0120] The adhesive resin layer contains one or more resin materials. Examples of resin materials include polyolefins, modified polyolefins, vinyl resins, polyethers, polyesters, polyamides, polyurethanes, silicone resins, epoxy resins, and phenolic resins. Among these, polyolefins and modified polyolefins are preferred from the viewpoint of recyclability and adhesion, and modified polyolefins such as acid-modified polyolefins are more preferred.

[0121] Examples of modified polyolefins include polyolefins modified with unsaturated carboxylic acids such as maleic acid and fumaric acid, or their acid anhydrides, esters, or metal salts, particularly graft-modified polyolefins. Among resin materials, modified polyolefins are preferred from the viewpoint of obtaining a structure suitable for monomaterial packaging materials.

[0122] The melt flow rate (MFR) of modified polyolefins is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.3 g / 10 min to 30 g / 10 min, even more preferably 0.5 g / 10 min to 10 g / 10 min, and particularly preferably 0.5 g / 10 min to 5.0 g / 10 min, from the viewpoint of film-forming properties and processability. The MFR of modified polyolefins is measured in accordance with ASTM D1238 under conditions of a temperature of 190°C and a load of 2.16 kg, but the measurement temperature may be changed according to the melting point of the modified polyolefin.

[0123] The adhesive resin layer may contain one or more of the above-mentioned additives.

[0124] The thickness of the adhesive resin layer is preferably 0.5 μm to 10 μm, more preferably 1.0 μm to 7.0 μm. If the thickness is above the lower limit, for example, the adhesion can be improved. If the thickness is below the upper limit, for example, the recyclability of the laminate can be improved.

[0125] (Functional resin layer) The stretched substrate is equipped with a functional resin layer. This allows for improvements in properties such as the gas barrier properties and heat resistance of the stretched substrate. In one embodiment, the functional resin layer is a gas barrier resin layer. This can improve, for example, the gas barrier properties (specifically, oxygen barrier properties and / or water vapor barrier properties) of the laminate. Furthermore, by forming a vapor-deposited film on the gas barrier resin layer, the adhesion of the vapor-deposited film can be improved, for example.

[0126] The gas barrier resin layer contains one or more gas barrier resins. Examples of gas barrier resins include polyamide, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyester, polyurethane, and (meth)acrylic resin. Among these, polyamide and ethylene-vinyl alcohol copolymer are preferred from the viewpoint of oxygen barrier properties and / or water vapor barrier properties.

[0127] Examples of polyamides include aliphatic polyamides and semi-aromatic polyamides. Aliphatic polyamides are preferred, and crystalline aliphatic polyamides are more preferred.

[0128] Examples of aliphatic polyamides include aliphatic homopolyamides and aliphatic copolymer polyamides. In the following examples, polyamide will also be referred to as "PA".

[0129] Aliphatic homopolyamides include, specifically, polycaprolactam (PA6), polyenanthractam (PA7), polyundecanelactam (PA11), polylauryllactam (PA12), polyhexamethyleneadipamide (PA66), polytetramethylenedodecamid (PA412), polypentamethyleneazeramid (PA59), polypentamethylenesebamide (PA510), polypentamethylenedodecamid (PA512), polyhexamethyleneazeramid (PA69), polyhexamethylenesebamide (PA610), polyhexamethylenedodecamid (PA612), and poly Examples include nonamethylene adipamide (PA96), polynonamethylene azeramide (PA99), polynonamethylene sevacamide (PA910), polynonamethylene dodecamide (PA912), polydecamethylene adipamide (PA106), polydecamethylene azeramide (PA109), polydecamethylene decamido (PA1010), polydecamethylene dodecamide (PA1012), polidodecamethylene adipamide (PA126), polidodecamethylene azeramide (PA129), polidodecamethylene sevacamide (PA1210), and polidodecamethylene dodecamide (PA1212).

[0130] Specifically, aliphatic copolymer polyamides include caprolactam / hexamethylenediaminoadipic acid copolymer (PA6 / 66), caprolactam / hexamethylenediaminoazelaic acid copolymer (PA6 / 69), caprolactam / hexamethylenediaminosebacic acid copolymer (PA6 / 610), caprolactam / hexamethylenediaminoundecanoic acid copolymer (PA6 / 611), caprolactam / hexamethylenediaminododecanoic acid copolymer (PA6 / 612), and caprolactam / amino Examples include undecanoic acid copolymer (PA6 / 11), caprolactam / lauryl lactam copolymer (PA6 / 12), caprolactam / hexamethylenediaminoadipic acid / lauryl lactam copolymer (PA6 / 66 / 12), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminosebacic acid copolymer (PA6 / 66 / 610), and caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminododecanedicarboxylic acid copolymer (PA6 / 66 / 612).

[0131] The relative viscosity of the aliphatic polyamide is preferably 1.5 to 5.0, more preferably 2.0 to 5.0, and even more preferably 2.5 to 4.5. The relative viscosity of the aliphatic polyamide is measured in accordance with JIS K6920 by dissolving 1 g of polyamide in 100 mL of 96% concentrated sulfuric acid and measuring at 25°C.

[0132] Semi-aromatic polyamides are polyamides having structural units derived from aromatic diamines and structural units derived from aliphatic dicarboxylic acids, or polyamides having structural units derived from aliphatic diamines and structural units derived from aromatic dicarboxylic acids. Examples include polyamides composed of aromatic diamines and aliphatic dicarboxylic acids, and polyamides composed of aliphatic diamines and aromatic dicarboxylic acids.

[0133] Specifically, the semi-aromatic polyamides include polyhexamethylene terephthalamide (PA6T), polyhexamethylene isophthalamide (PA6I), polynonamethylene terephthalamide (PA9T), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (PA66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (PA66 / 6I), polyhexamethylene terephthalamide / polycaproamide copolymer (PA6T / 6), polyhexamethylene isophthalamide / polycaproamide copolymer (PA6I / 6), and polyhexamethylene terephthalamide / poly Examples include lidodecamid copolymer (PA6T / 12), polyhexamethylene isophthalamide / polyhexamethylene terephthalamide copolymer (PA6I / 6T), polyhexamethylene terephthalamide / poly(2-methylpentamethylene terephthalamide) copolymer (PA6T / M5T), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (PA66 / 6T / 6I), polyhexamethylene adipamide / polycaproamide / polyhexamethylene isophthalamide copolymer (PA66 / 6 / 6I), and polymetaxylylene adipamide (PAMXD6).

[0134] The melt volume rate (MVR) of the semi-aromatic polyamide is preferably 5 cm². 3 / 10 minutes or more 200cm 3 / 10 minutes or less, or more preferably 10 cm 3 / 100cm for more than 10 minutes 3 The time is less than 10 minutes. MVR is measured in accordance with ISO 1133 at a temperature of 275°C and a load of 5 kg.

[0135] In one embodiment, the gas barrier resin layer contains a crystalline aliphatic polyamide. Examples of crystalline aliphatic polyamides include PA6, PA11, PA12, PA66, PA610, PA612, PA6 / 66, and PA6 / 66 / 12.

[0136] The melting point (Tm) of the crystalline aliphatic polyamide is preferably 180°C to 300°C, more preferably 180°C to 250°C, and even more preferably 180°C to 230°C. In this disclosure, Tm is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0137] In ethylene-vinyl alcohol copolymers (EVOH), the content of ethylene-derived constituent units (ethylene content) is preferably 20 mol% to 60 mol%, more preferably 25 mol% to 50 mol%. If the ethylene content is above the lower limit, for example, the processability of the laminate can be improved. If the ethylene content is below the upper limit, for example, the oxygen barrier properties and / or water vapor barrier properties of the laminate can be improved. The ethylene content is measured by NMR spectroscopy.

[0138] The melting point (Tm) of EVOH is preferably 130°C to 200°C, more preferably 140°C to 195°C, and even more preferably 150°C to 190°C.

[0139] The melt flow rate (MFR) of EVOH is preferably 0.1 g / 10 min to 30 g / 10 min, more preferably 0.3 g / 10 min to 20 g / 10 min, and even more preferably 0.5 g / 10 min to 10 g / 10 min, from the viewpoint of film-forming properties and processability. The MFR of EVOH is measured in accordance with ASTM D1238 under conditions of a temperature of 190°C and a load of 2.16 kg, although the measurement temperature may be 210°C depending on the melting point of EVOH.

[0140] The gas barrier resin content in the gas barrier resin layer is preferably 50% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, 85% by mass or more, or 90% by mass or more. This can improve, for example, the oxygen barrier properties and / or water vapor barrier properties of the laminate.

[0141] In one embodiment, the functional resin layer is a heat-resistant resin layer. This can improve the heat resistance of the laminate, for example, and broaden the temperature range during heat sealing.

[0142] In one embodiment, the heat-resistant resin layer contains one or more resins having a melting point of 180°C or higher (hereinafter also referred to as "high-melting-point resins"). Examples of high-melting-point resins include polyamides, polyimides, polyesters, polyolefins, vinyl resins, (meth)acrylic resins, cellulose resins, and ionomer resins, all of which have a melting point of 180°C or higher.

[0143] The melting point of the high-melting-point resin is 180°C or higher, preferably 185°C or higher. A melting point above the lower limit can, for example, further improve the heat resistance of the stretched substrate and, moreover, improve the adhesion of the vapor-deposited film. The melting point of the high-melting-point resin is preferably 250°C or lower, more preferably 230°C or lower. This can, for example, improve the film-forming properties of the functional resin layer.

[0144] As the high-melting-point resin, a resin having polar groups is preferred. A polar group refers to a group containing one or more heteroatoms, and examples include ester groups, epoxy groups, hydroxyl groups, amino groups, amide groups, urethane groups, carboxyl groups, carbonyl groups, carboxylic acid anhydride groups, sulfo groups, thiol groups, and halogen groups. Among these, from the viewpoint of gas barrier properties and laminate strength of the packaging container, hydroxyl groups, ester groups, amino groups, amide groups, carboxyl groups, and carbonyl groups are preferred, with amide groups being more preferred. By forming a vapor-deposited film on a heat-resistant resin layer made of such a resin, for example, the adhesion of the vapor-deposited film can be improved.

[0145] Examples of high-melting-point resins having polar groups include polyamides, polyesters, ethylene-vinyl alcohol copolymers, and polyvinyl alcohols, with a melting point of 180°C or higher, and polyamides are preferred. By providing a heat-resistant resin layer made of polyamide, in addition to gas barrier properties and heat resistance, the pinhole resistance and abrasion resistance of the laminate can be improved, for example.

[0146] The content of high-melting-point resin in the heat-resistant resin layer is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, 85% by mass or more, or 90% by mass or more. This can improve the heat resistance of the laminate, for example.

[0147] The difference between the melting point of the resin contained in the functional resin layer and the melting point of the polyethylene contained in the base layer is preferably 90°C or less, more preferably 80°C or less, and even more preferably 70°C or less. When the above difference is below the upper limit, for example, the film-forming properties of the stretched base material can be improved.

[0148] The functional resin layer may contain one or more additives. Examples of additives include crosslinking agents, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, compatibilizers, and pigments.

[0149] The thickness of the functional resin layer is preferably 0.5 μm to 10 μm, more preferably 1.0 μm to 7.0 μm. If the thickness is above the lower limit, for example, the effects of the functional resin layer can be improved. If the thickness is below the upper limit, for example, the recyclability of the laminate can be improved.

[0150] In one embodiment, the thickness of the functional resin layer is preferably smaller than the thickness of the base layer. This can improve, for example, the recyclability of the laminate. The thickness of the functional resin layer is preferably 5 μm or more smaller than the thickness of the base layer, and more preferably 10 μm or more smaller.

[0151] <Vaporized film> In one embodiment, the laminate of this disclosure may include a vapor-deposited film formed on the sealant layer side surface of the stretched substrate. This can improve, for example, the oxygen barrier properties and water vapor barrier properties of the laminate. In one embodiment, the vapor-deposited film is provided on the surface of the functional resin layer of the stretched substrate.

[0152] Examples of vapor-deposited films include metals such as aluminum, chromium, tin, nickel, copper, silver, gold, and platinum; or inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, and silicon carbide oxide (carbon-containing silicon oxide). Among these, aluminum vapor-deposited films, aluminum oxide (alumina) vapor-deposited films, silicon oxide (silica) vapor-deposited films, or carbon-containing silicon oxide vapor-deposited films are preferred.

[0153] The carbon-containing silicon oxide vapor-deposited film contains silicon, oxygen, and carbon. In one embodiment of a carbon-containing silicon oxide vapor-deposited film, the carbon content C is preferably 3% to 50%, more preferably 5% to 40%, and even more preferably 10% to 35%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. By setting the carbon content C within the above range, for example, a decrease in gas barrier properties can be suppressed even when the laminate is bent. In this specification, the proportions of each element are expressed on a molar basis.

[0154] In one embodiment of a carbon-containing silicon oxide vapor-deposited film, the silicon content (Si) is preferably 1% to 45%, more preferably 3% to 38%, and even more preferably 8% to 33%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. The oxygen content (O) is preferably 10% to 70%, more preferably 20% to 65%, and even more preferably 25% to 60%, relative to 100% of the total of the three elements silicon, oxygen, and carbon. By setting the silicon content (Si) and oxygen content (O) within the above ranges, for example, the decrease in gas barrier properties can be further suppressed even when the laminate is bent.

[0155] In one embodiment of a carbon-containing silicon oxide vapor-deposited film, the proportion of oxygen (O) is preferably higher than the proportion of carbon (C), and the proportion of silicon (Si) is preferably lower than the proportion of carbon (C). The proportion of oxygen (O) is preferably higher than the proportion of silicon (Si), meaning that the proportions are preferably decreasing in the order of O, C, and Si. This allows for a more suppression of the decrease in gas barrier properties, for example, even when the laminate is bent.

[0156] The proportions of C, Si, and O in a carbon-containing silicon oxide vapor-deposited film can be measured by X-ray photoelectron spectroscopy (XPS) using narrow-scan analysis under the following measurement conditions.

[0157] (Measurement conditions) Equipment used: "ESCA-3400" (manufactured by Kratos) [1] Spectrum acquisition conditions Incident X-ray: MgKα (monochromatic X-ray, hν=1253.6eV) X-ray output: 150W (10kV 15mA) X-ray scanning area (measurement area): Approximately 6 mmφ Photoelectron capture angle: 90 degrees [2] Ion sputtering conditions Ionic species: Ar + Acceleration voltage: 0.2 (kV) Emission current: 20 (mA) Etching area: 10mmφ Ion sputtering was performed for 30 seconds, and the spectrum was collected.

[0158] The thickness of the deposited film is preferably 1 nm to 150 nm, more preferably 5 nm to 60 nm, and even more preferably 10 nm to 40 nm. By setting the thickness of the deposited film to 1 nm or more, for example, the oxygen barrier and water vapor barrier properties of the laminate can be further improved. By setting the thickness of the deposited film to 150 nm or less, for example, the occurrence of cracks in the deposited film can be suppressed, and the recyclability of the laminate can be improved.

[0159] Examples of methods for forming a vapor-deposited film include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating; and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition. The vapor-deposited film may be a composite film containing two or more vapor-deposited films of different inorganic oxides, formed by using both physical vapor deposition and chemical vapor deposition methods in combination.

[0160] The vacuum level of the deposition chamber before oxygen introduction was 10 -2 ~10 -8 A bar of approximately mbar is preferred, and after oxygen introduction, 10 -1 ~10 -6 A pressure of approximately mbar is preferred. The amount of oxygen introduced will vary depending on the size of the deposition machine. Inert gases such as argon, helium, and nitrogen may be used as carrier gases for the oxygen introduced, within reasonable limits. The transport speed of the film to which the deposited film is formed is, for example, 10 m / min to 800 m / min.

[0161] The surface of the deposited film may be subjected to the surface treatment described above. This can improve, for example, the adhesion between the deposited film and the layer adjacent to it.

[0162] <Barrier Coat Layer> For example, if the vapor-deposited film is composed of inorganic oxides such as aluminum oxide, silicon oxide, and silicon carbide oxide, a barrier coating layer may be provided on the surface of the vapor-deposited film. By adopting such a configuration, for example, the gas barrier properties of the laminate can be improved, and the occurrence of cracks in the vapor-deposited film can be effectively suppressed.

[0163] In one embodiment, the barrier coating layer contains a gas barrier resin as its main component. Examples of gas barrier resins include polyesters such as ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamides such as nylon 6, nylon 6,6, and polymethoxyylene adipamide, polyurethanes, and (meth)acrylic resins.

[0164] The gas barrier resin content 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 this configuration, for example, the gas barrier properties of the barrier coat layer can be improved.

[0165] The thickness of the barrier coating layer is preferably 0.01 μm to 10.0 μm, and more preferably 0.1 μm to 5.0 μm. By making the barrier coating layer thickness 0.01 μm or more, for example, the gas barrier properties can be further improved.

[0166] A barrier coating layer can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or a suitable organic solvent, and then applying and drying the resulting coating solution. Alternatively, a barrier coating layer can be formed by applying and drying a commercially available barrier coating agent.

[0167] In another embodiment, the barrier coat layer is a gas barrier coating layer formed by mixing a metal alkoxide, a water-soluble polymer, and optionally a silane coupling agent, adding water, an organic solvent, and a sol-gel catalyst to obtain a gas barrier composition, applying it to a vapor-deposited film, and drying it. The gas barrier coating layer contains hydrolyzed polycondensates obtained by hydrolysis and polycondensation of the metal alkoxide, etc., by the sol-gel method. By providing such a barrier coat layer on the vapor-deposited film, the occurrence of cracks in the vapor-deposited film can be effectively suppressed. Each of the above components can be used individually or in combination of two or more.

[0168] Metal alkoxides are represented, for example, by formula (1). R 1 n M(OR 2 ) m (1) In formula (1), R 1 and R 2 Each of these independently represents an organic group with 1 to 8 carbon atoms, M represents a metal atom, n represents an integer greater than or equal to 0, m represents an integer greater than or equal to 1, and n+m represents the valence of M.

[0169] R 1 and R 2 Examples of organic groups in this context include alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-hexyl, and n-octyl groups. The metal atom M is, for example, silicon, zirconium, titanium, or aluminum.

[0170] Examples of metal alkoxides include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0171] Examples of water-soluble polymers include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Depending on the desired physical properties such as oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance, either polyvinyl alcohol or ethylene-vinyl alcohol copolymer may be used, or both may be used in combination. Alternatively, a gas barrier coating layer obtained using polyvinyl alcohol and a gas barrier coating layer obtained using ethylene-vinyl alcohol copolymer may be laminated. The amount of water-soluble polymer used is preferably 5 parts by mass or more and 500 parts by mass or less per 100 parts by mass of metal alkoxide.

[0172] As the silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used, and organoalkoxysilanes having an epoxy group are preferred, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The amount of silane coupling agent used is preferably 1 to 20 parts by mass per 100 parts by mass of metal alkoxide.

[0173] The gas barrier composition may contain water in a ratio of preferably 0.1 moles to 100 moles, more preferably 0.5 moles to 60 moles, per mole of metal alkoxide. By setting the water content above the lower limit, for example, the oxygen barrier and water vapor barrier properties of the laminate can be improved. By setting the water content below the upper limit, for example, hydrolysis reactions can be carried out rapidly.

[0174] Examples of organic solvents used in the preparation of gas barrier compositions include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, and n-butyl alcohol.

[0175] Acids or amine compounds are preferred as catalysts for the sol-gel method. Examples of acids include mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid; and organic acids such as acetic acid and tartaric acid. The amount of acid used is preferably 0.001 moles or more and 0.05 moles or less per mole of the total molar amount of the alkoxide portion (e.g., silicate portion) of the metal alkoxide and the silane coupling agent.

[0176] Examples of amine compounds include N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. The amount of amine compound used is preferably 0.01 parts by mass or more and 1.0 part by mass or less, based on 100 parts by mass of the total amount of the metal alkoxide and silane coupling agent.

[0177] Methods for applying the gas barrier composition include, for example, roll coating such as gravure roll coaters, spray coating, spin coating, dipping, brushing, bar coating, and application methods such as applicators.

[0178] The following describes one embodiment of a method for forming a gas barrier coating layer. 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 gradually proceeds within the composition. The composition is applied to a vapor-deposited film by a conventional method and dried. This drying further promotes the polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains one), forming a composite polymer layer. Multiple composite polymer layers may be laminated by repeating the above operation. For example, the applied composition is heated at a temperature preferably between 20°C and 150°C, more preferably between 50°C and 120°C, and even more preferably between 50°C and 100°C for 1 second to 10 minutes. This forms a gas barrier coating layer.

[0179] The thickness of the gas barrier coating layer is preferably 0.01 μm to 10.0 μm, more preferably 0.1 μm to 5.0 μm, and even more preferably 0.1 μm to 2.0 μm. This allows for improved gas barrier properties and suppression of crack formation in the vapor-deposited film.

[0180] <Print layer> In one embodiment, the laminate of the present disclosure may further comprise a printed layer formed on the stretched substrate described above. In one embodiment, it is preferable that the printed layer be provided on the sealant layer side of the stretched substrate so as to suppress image degradation over time. If the laminate comprises a vapor-deposited film or a barrier coat layer on the stretched substrate, for example, the printed layer may be provided on the sealant layer side of the vapor-deposited film or barrier coat layer.

[0181] The printed layer includes, for example, an image. Examples of images include characters, figures, symbols, and combinations thereof. Examples of methods for forming the printed layer include gravure printing, offset printing, and flexographic printing. In one embodiment, flexographic printing is preferred from the viewpoint of reducing environmental impact. Also, from the viewpoint of reducing environmental impact, the printed layer may be formed on the surface of a substrate or the like using biomass-derived ink.

[0182] The thickness of the printed layer is preferably 0.1 μm to 10.0 μm, more preferably 0.2 μm to 5.0 μm, and even more preferably 0.3 μm to 3.0 μm.

[0183] <Anchor Coat Layer> In one embodiment, the laminate of the present disclosure may further include an anchor coat layer between the stretched substrate and the extruded resin layer. This can improve, for example, the interlayer adhesion in the laminate. The anchor coat layer is formed of an anchor coat agent. In this embodiment, the extruded resin layer is in contact with the anchor coat layer.

[0184] Examples of anchor coating agents include polyurethane-based, polyolefin-based, or epoxy resin-based anchor coating agents. In one embodiment, the anchor coating agent is a two-component curing resin, for example, consisting of a polyol as the main component and a polyisocyanate as the curing agent.

[0185] Examples of polyols include polyether polyols, polyester polyols, and (meth)acrylic polyols. Examples of polyisocyanates include aromatic polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenylene polyisocyanate, as well as aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate.

[0186] In one embodiment, the anchor coat layer is made of polyurethane obtained by the reaction of a polyol and a polyisocyanate. Specific examples of polyurethane include polyether polyurethane, polyester polyurethane, and poly(meth)acrylic polyurethane.

[0187] The anchor coat layer can be formed, for example, by applying an anchor coat agent to a stretched substrate or the printed layer-forming surface of a stretched substrate. The anchor coat agent can be applied by coating methods such as the roll coating method, gravure roll coating method, and kiss coating method, or by printing methods.

[0188] 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, and more preferably 0.2 μm or more and 1.0 μm or less.

[0189] <Extruded resin layer> The laminate of this disclosure comprises an extruded resin layer mainly composed of polyethylene between a stretched substrate and a sealant layer. The extruded resin layer functions as an adhesive layer between the stretched substrate and the sealant layer, or as an adhesive layer between the laminate comprising the stretched substrate and the sealant layer. The laminate comprising the stretched substrate comprises, for example, a stretched substrate and other layers such as a vapor-deposited film, a barrier coat layer, a printed layer, and an anchor coat layer.

[0190] The laminate of this disclosure includes an extruded resin layer containing polyethylene as the main component as an adhesive layer between the stretched substrate or the laminate and the sealant layer. This allows for a higher polyethylene content in the laminate compared to when conventional non-polyethylene adhesives (e.g., two-component curing polyurethane adhesives) are used. This improves the recyclability of the laminate.

[0191] The extruded resin layer contains polyethylene as its main component. Details of the polyethylene are as described above. The polyethylene in the extruded resin layer and the polyethylene in the base layer of the stretched base material may be the same or different.

[0192] From the viewpoint of adhesion, at least one polyethylene selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene is preferred as the polyethylene constituting the extruded resin layer, with low-density polyethylene or linear low-density polyethylene being more preferred. Biomass polyethylene or mechanically or chemically recycled polyethylene may also be used.

[0193] The melt flow rate (MFR) of the polyethylene constituting the extruded resin layer is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, and even more preferably 3.0 g / 10 min to 20 g / 10 min, from the viewpoint of film-forming properties and the processability of the laminate.

[0194] The melting point (Tm) of the polyethylene constituting the extruded resin layer is preferably 100°C to 140°C, more preferably 100°C to 130°C, and even more preferably 100°C to 120°C, from the viewpoint of balancing heat resistance and adhesiveness.

[0195] The extruded resin layer may contain one or more types of polyethylene. The polyethylene content in the extruded resin layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. This configuration can improve, for example, the recyclability of the laminate.

[0196] In one embodiment, the extruded resin layer contains biomass polyethylene. In this case, the biomass content of the extruded resin layer may be, for example, 30% or more, 50% or more, or 70% or more. The upper limit of the biomass content is not particularly limited, but may be, for example, 99% or 98%.

[0197] In the laminate of this disclosure, the thickness of the extruded resin layer as the adhesive layer is preferably 5 μm to 40 μm, more preferably 10 μm to 30 μm. This improves, for example, adhesion and recyclability.

[0198] The extruded resin layer can be formed, for example, by melting polyethylene or a polyethylene resin composition and extruding it onto a stretched substrate or a laminate comprising the stretched substrate. The melting temperature at this time is, for example, 280°C to 340°C, preferably 290°C to 335°C.

[0199] In one embodiment, this disclosure uses a melt extrusion lamination method, particularly a sand lamination method, using a molten resin mainly containing polyethylene as a component, to bond a stretched substrate or a laminate comprising the stretched substrate to a polyethylene film as a sealant layer. This makes it possible to increase the polyethylene content of the laminate. Furthermore, in this disclosure, the time required for the drying and aging processes can be reduced compared to laminating the stretched substrate or the laminate with the sealant layer by, for example, dry lamination, and therefore the production efficiency of the laminate can be improved.

[0200] <Sealant layer> The laminate of this disclosure comprises a polyethylene layer as a sealant layer. The polyethylene layer contains polyethylene as its main component. In one embodiment, the polyethylene layer serving as the sealant layer is an unstretched layer (unstretched polyethylene layer). An unstretched layer is a layer that has not undergone stretching treatment, for example, an extruded film that has not undergone stretching treatment. Details of the stretching treatment are as described above in the description of the substrate.

[0201] The details of polyethylene are as described above. The polyethylene in the sealant layer, the polyethylene in the base layer of the stretched substrate, or the polyethylene in the extruded resin layer may be the same or different.

[0202] The melt flow rate (MFR) of the polyethylene constituting the sealant layer is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.2 g / 10 min to 30 g / 10 min, and even more preferably 0.3 g / 10 min to 20 g / 10 min, from the viewpoint of film-forming properties and the processability of the laminate.

[0203] The melting point (Tm) of the polyethylene constituting the sealant layer is preferably 90°C to 140°C, more preferably 90°C to 130°C, and even more preferably 90°C to 120°C, from the viewpoint of balancing heat resistance and heat sealability.

[0204] From the viewpoint of heat-sealability, at least one polyethylene selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene is preferred for the polyethylene constituting the sealant layer, with linear low-density polyethylene being more preferred. Biomass polyethylene, or mechanically or chemically recycled polyethylene may also be used.

[0205] The sealant layer may contain one or more types of polyethylene. The polyethylene content in the sealant layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. With such a configuration, for example, the recyclability of the packaging material made of the laminate of this disclosure can be improved.

[0206] The sealant layer may contain one or more resin materials other than polyethylene. Examples of such resin materials include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins.

[0207] The sealant layer may contain one or more additives. Examples of additives include crosslinking agents, lubricants, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins.

[0208] The sealant layer may have a single-layer structure or a multi-layer structure. In one embodiment, the number of layers in the multilayer sealant layer is between 2 and 7, for example, between 3 and 7, or between 3 and 5. The number of layers in the sealant layer is preferably an odd number, for example, 3, 5, or 7. With such a configuration, for example, the symmetry of the laminated structure of the sealant layer is increased, and the occurrence of curling in the sealant layer can be suppressed.

[0209] In one embodiment, the multilayer sealant layer is a co-extruded resin film, and each layer constituting the sealant layer is a co-extruded resin layer. The co-extruded resin film can be manufactured, for example, by forming a film using the inflation method or the T-die method.

[0210] 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. The total thickness of the sealant layer is preferably changed as appropriate depending on the mass of the contents contained in the packaging container described later, from the viewpoint of the strength and processability of the sealant layer.

[0211] For example, if the packaging container is a small bag, the total thickness of the sealant layer is preferably 20 μm to 60 μm. In this case, for example, contents weighing 1 g to 200 g can be well contained within the small bag. If the sealant layer is thin, when the stretched substrate and the sealant film are bonded together using a conventional non-polyethylene adhesive, the polyethylene content in the entire laminate decreases significantly. In one embodiment of this disclosure, the stretched substrate and the sealant film are bonded together with an extruded resin layer mainly containing polyethylene, which allows for a higher polyethylene content.

[0212] For example, if the packaging container is a standing pouch, the total thickness of the sealant layer is preferably 40 μm to 200 μm, more preferably 60 μm to 150 μm. In this case, for example, contents weighing 50 g to 2000 g can be well contained within the standing pouch.

[0213] In one embodiment, the sealant layer contains biomass polyethylene. In this case, the biomass content of the sealant layer may be, for example, 10% or more, 10% to 80%, 20% to 75%, or 30% to 70%.

[0214] If the sealant layer has a multilayer structure, that is, if the sealant layer comprises two or more resin layers mainly composed of polyethylene, at least one of the resin layers may contain biomass polyethylene.

[0215] The laminate of this disclosure may include a vapor-deposited film formed on the stretched substrate side surface of the sealant layer. This can improve, for example, the oxygen barrier properties and water vapor barrier properties of the laminate.

[0216] 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. This can improve, for example, the adhesion between the deposited film and the layer adjacent to it.

[0217] [Application] The laminates of this disclosure can be suitably used for packaging material applications. The packaging material is used to manufacture a packaging container. The packaging material comprises the laminate of the present disclosure. A packaging container can be manufactured by using at least the packaging material comprising the laminate of the present disclosure.

[0218] The packaging container comprises the laminate of the present disclosure. Examples of packaging containers include packaging bags, tube containers, and containers with lids. A container with a lid comprises a container body having a storage compartment and a lid material joined (heat-sealed) to the container body to seal the storage compartment.

[0219] Examples of heat sealing methods include bar seals, rotary roll seals, belt seals, impulse seals, high-frequency seals, and ultrasonic seals.

[0220] Examples of packaging bags include various types such as standing pouch type, side seal type, two-side seal type, three-side seal type, four-side seal type, envelope seal type, gusset seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, and gusset type.

[0221] The packaging bag may be equipped with an easy-open section. Examples of easy-open sections include a notch that serves as the starting point for tearing the packaging bag, and a half-cut line formed by laser processing or a cutter as a path when tearing the packaging bag.

[0222] In one embodiment, a packaging bag can be made by folding the laminate of the present disclosure in half so that the stretched base material is on the outside and the sealant layer is on the inside, overlapping the two halves, and then heat-sealing the edges. In another embodiment, a packaging bag can be made by overlapping multiple laminates of the present disclosure so that the sealant layers face each other, and then heat-sealing the edges. The entire packaging bag may be made of the above laminate, or only a part of the packaging bag may be made of the above laminate.

[0223] In one embodiment, the laminate of the present disclosure is used as a lid material for a container with a lid.

[0224] Examples of contents that can be contained in the packaging container include liquids, solids, powders, and gels. The contents may be food or beverages, or non-food items such as chemicals, cosmetics, and pharmaceuticals. After the contents are placed in the packaging container, the container can be sealed by heat-sealing the opening.

[0225] As specific examples of packaging bags, small bags and standing pouches will be described below. A small pouch is a small packaging bag used to contain contents weighing, for example, 1g to 200g. Examples of contents that can be contained in a small pouch include sauces, soy sauce, dressings, ketchup, syrups, cooking alcoholic beverages, other liquid or viscous seasonings; liquid soups, powdered soups, fruit juices; spices; liquid beverages, jelly beverages, instant foods, and other food and beverages.

[0226] Standing pouches are used to contain contents ranging from 50g to 2000g. Examples of contents that can be contained in standing pouches include shampoo, rinse, conditioner, hand soap, body soap, fragrances, deodorizers, insect repellents, detergents; dressings, cooking oils, mayonnaise, and other liquid or viscous condiments; liquid beverages, jelly beverages, instant foods, and other food and beverages; and creams.

[0227] Figure 6 is a simplified diagram showing an example of the configuration of a standing pouch. In the figure, the shaded area represents the heat-sealed portion. As shown in Figure 6, in one embodiment, the standing pouch 40 comprises a body (side sheet) 41 and a bottom (bottom sheet) 42. The side sheet 41 and the bottom sheet 42 may be made of the same material or of different materials. By the bottom sheet maintaining the shape of the side sheet, the pouch is given self-supporting ability and can be made into a standing type pouch. A storage space for containing contents is formed within the area enclosed by the side sheet and the bottom sheet.

[0228] In a standing pouch, the body may be made only of the laminate of the Disclosure, the bottom may be made only of the laminate of the Disclosure, or both the body and the bottom may be made of the laminate of the Disclosure.

[0229] In one embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them so that the sealant layers face each other, and heat-sealing the side edges on both sides to form a bag.

[0230] In another embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them so that the sealant layers face each other, inserting two V-shaped folded laminates between the laminates at the side edges on both sides of the overlapped laminates so that the sealant layers face outwards, and then heat sealing them. According to this manufacturing method, a standing pouch 40 having a body portion 41 with side gussets 43 as shown in Figure 7 can be obtained.

[0231] In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the lower parts of the bag-formed side sheets and heat-sealing it. More specifically, the bottom sheet can be formed by inserting a laminate folded in a V-shape with the sealant layer facing outwards between the lower parts of the bag-formed side sheets and heat-sealing it.

[0232] In one embodiment, two of the above-mentioned laminates are prepared and stacked so that the sealant layers face each other. Then, the other laminate is folded into a V-shape so that the sealant layer faces outwards, and this is sandwiched between the bottoms of the two stacked laminates and heat-sealed to form the bottom. Next, the two sides adjacent to the bottom are heat-sealed to form the body. In this way, a standing pouch of one embodiment can be formed.

[0233] This disclosure relates, for example, to the following [1] to

[12] . [1] A laminate comprising a stretched substrate and a sealant layer, wherein the stretched substrate comprises a substrate layer mainly containing polyethylene and a functional resin layer, the sealant layer mainly containing polyethylene, and the laminate comprises an extruded resin layer mainly containing polyethylene between the stretched substrate and the sealant layer. [2] The laminate according to [1] above, wherein the functional resin layer is a gas barrier resin layer or a heat-resistant resin layer. [3] The laminate according to [1] or [2] above, wherein the stretched substrate further comprises an adhesive resin layer between the substrate layer and the functional resin layer. [4] The laminate according to any one of [1] to [3] above, wherein the stretched substrate is a substrate that has undergone uniaxial stretching or biaxial stretching. [5] The laminate according to any one of [1] to [4] above, further comprising a vapor-deposited film formed on the surface of the sealant layer side of the stretched substrate. [6] The laminate according to any one of [1] to [5] above, further comprising a printed layer on the sealant layer side of the stretched substrate. [7] The laminate according to any one of [1] to [6] above, wherein the laminate further comprises an anchor coat layer between the stretched substrate and the extruded resin layer, and the extruded resin layer is in contact with the anchor coat layer. [8] A laminate according to any of [1] to [7] above, wherein the thickness of the sealant layer is 20 μm or more and 60 μm or less. [9] A laminate according to any of [1] to [8] above, wherein the polyethylene content is 90% by mass or more of 100% by mass of the laminate.

[10] A laminate according to any of the above [1] to [9], used for packaging material applications.

[11] Packaging material comprising a laminate as described in any of [1] to

[10] above.

[12] A packaging container comprising the laminate described in any of [1] to

[10] above. [Examples]

[0234] The laminates of this disclosure will be described in more detail based on examples, but the laminates of this disclosure are not limited in any way by the examples.

[0235] In the following descriptions, medium-density polyethylene will also be referred to as "MDPE," low-density polyethylene as "LDPE," and linear low-density polyethylene as "LLDPE." Anchor coating agents are also referred to as "AC agents." The polyethylene extruded resin layer is also referred to as "EC-PE". Polyurethane adhesive is also sometimes referred to as "PU adhesive."

[0236] [Preparation of stretched substrates (substrate films)] <Preparation of uniaxially oriented film (A)> MDPE (density: 0.940g / cm 3 (Melting point: 128℃, MFR: 0.25g / 10min, ExxonMobil, product name: Enable4002) and adhesive resin (density: 0.890g / cm³) 3 (Melting point: 128℃, MFR: 2.6g / 10min, Mitsui Chemicals, Inc., Product name: Admer AT1955E) and gas barrier resin (density: 1.14g / cm³) 3A film was co-extruded using Kraray's EVALE171B (melting point: 165°C, MFR: 1.7g / 10min) by inflation molding to obtain a 125 μm thick film consisting of an MDPE layer, an adhesive resin layer, and a gas barrier resin layer in that order. The MDPE layer was 100 μm thick, the adhesive resin layer was 12.5 μm thick, and the gas barrier resin layer was 12.5 μm thick. This film was stretched longitudinally (MD) at a stretching ratio of 5 times to obtain a stretched film with a thickness of 25 μm. The gas barrier resin layer surface of this stretched film was subjected to corona treatment to adjust the wettability index to 52 dyn. The substrate thus obtained is also referred to as "uniaxially oriented film (A)". The haze value of uniaxially oriented film (A) was measured in accordance with JIS K7136 and was 10.3%.

[0237] <Preparation of uniaxially oriented film (B)> MDPE (density: 0.940g / cm 3 (Melting point: 128℃, MFR: 0.25g / 10min, ExxonMobil, product name: Enable4002) and adhesive resin (density: 0.890g / cm³) 3 (Melting point: 128℃, MFR: 2.6g / 10min, Mitsui Chemicals, Inc., Product name: Admer AT1955E) and heat-resistant resin (density: 1.12g / cm³) 3 A film was co-extruded using an inflation molding method with BASF's Ultramid C40LN (melting point: 189°C) to obtain a 125 μm thick film consisting of an MDPE layer, an adhesive resin layer, and a heat-resistant resin layer in that order. The MDPE layer was 100 μm thick, the adhesive resin layer was 12.5 μm thick, and the heat-resistant resin layer was 12.5 μm thick. This film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain a stretched film with a thickness of 25 μm. The heat-resistant resin layer surface of this stretched film was subjected to corona treatment to adjust the wettability index to 52 dyn. The substrate obtained in this way is also referred to as "uniaxially oriented film (B)". The haze value of uniaxially oriented film (B) was 10.7%.

[0238] [Preparation of barrier coating agent] 385 g of water, 67 g of isopropyl alcohol, and 9.1 g of 0.5 N hydrochloric acid were mixed to obtain a solution with a pH of 2.2. To this solution, 175 g of tetraethoxysilane as a metal alkoxide and 9.2 g of glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed while cooling to 10°C to obtain Solution A. 14.7 g of polyvinyl alcohol with a saponification degree of 99% or more and a polymerization degree of 2400 as a water-soluble polymer, 324 g of water, and 17 g of isopropyl alcohol were mixed to obtain Solution B. Solution A and Solution B were mixed so as to be 6.5:3.5 on a mass basis (Solution A:Solution B) to obtain a barrier coating agent.

[0239] [Example 1-1] A uniaxially stretched film (A) and an unstretched LLDPE film with a thickness of 50 μm (Mitsui Chemicals Tohcello, Inc., TUX-TCS) were prepared. Flexographic printing was performed on the corona-treated surface of the uniaxially stretched film (A) using an aqueous flexographic ink (Toyobo Co., Ltd., trade name: Aquario) to form a printing layer with a thickness of 1 μm. A two-component curable polyurethane adhesive (Mitsui Chemicals, Inc., A-3210 / A-3075) as an anchor coating agent was applied to the surface where the printing layer was formed to form an anchor coating layer with a thickness of 0.3 μm. In this way, a laminate composed of the uniaxially stretched film (A), the printing layer, and the anchor coating layer was obtained. On the anchor coating layer of the laminate, LDPE (density: 0.918 g / cm 3 , melting point: 106°C, MFR: 7.0 g / 10 min, Japan Polyethylene Corporation, trade name: Novatec LC600A) was melt-extruded while the thickness of the extruded resin layer was 15 μm, and the laminate and the unstretched LLDPE film were sand laminated. In this way, a laminate was obtained.

[0240] [Examples 1-2] A laminate was obtained in the same manner as in Example 1-1 except that the uniaxially stretched film (A) was replaced with a uniaxially stretched film (B).

[0241] [Comparative Example 1-1] An uniaxially stretched film (A) and an unstretched LLDPE film with a thickness of 50 μm (Mitsui Chemicals Toatsu Chemicals, Inc., TUX-TCS) were prepared. Flexographic printing was performed on the corona-treated surface of the uniaxially stretched film (A) using an aqueous flexographic ink (Toyobo Co., Ltd., trade name: Aquario) to form a printing layer with a thickness of 1 μm. In this way, a laminate composed of the uniaxially stretched film (A) and the printing layer was obtained. The printing layer formation surface of the laminate and the corona-treated surface of the unstretched LLDPE film were laminated through an adhesive layer with a thickness of 4 μm composed of a two-component curable polyurethane adhesive (Rock Paint Co., Ltd., RU-77T / H-7) to obtain a laminate.

[0242] [Comparative Example 1-2] A laminate was obtained in the same manner as in Comparative Example 1-1, except that the uniaxially stretched film (B) was used instead of the uniaxially stretched film (A).

[0243] [Example 2-1] An uniaxially stretched film (B) and an unstretched LLDPE film with a thickness of 30 μm (Mitsui Chemicals Toatsu Chemicals, Inc., TUX-TCS) were prepared. An aluminum vapor deposition film with a thickness of 20 nm was formed on the corona-treated surface of the uniaxially stretched film (B) by the PVD method. Flexographic printing was performed on the aluminum vapor deposition film using an aqueous flexographic ink (Toyobo Co., Ltd., trade name: Aquario) to form a printing layer with a thickness of 1 μm. A two-component curable polyurethane adhesive (Mitsui Chemicals, Inc., A-3210 / A-3075) was applied as an anchor coat agent to the printing layer formation surface to form an anchor coat layer with a thickness of 0.3 μm. In this way, a laminate composed of the uniaxially stretched film (B), the vapor deposition film, the printing 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 melt-extruded while the thickness of the extruded resin layer was 15 μm, and the laminate and the unstretched LLDPE film were sand-laminated. In this way, a laminate was obtained.

[0244] [Example 2-2] A uniaxially oriented film (B) and an unstretched LLDPE film with a thickness of 40 μm (Mitsui Chemicals Tohcello Co., Ltd., TUX-TCS) were prepared. A 20 nm thick carbon-containing silicon oxide vapor-deposited film was formed on the corona-treated surface of the uniaxially oriented film (B) by CVD. The prepared barrier coating agent was applied to the vapor-deposited film to form a 300 nm thick barrier coating layer. A 1 μm thick printed layer was formed by flexographic printing on the barrier coating layer using an aqueous flexographic ink (Toyo Ink Co., Ltd., product name: Aquariona). A two-component curable polyurethane adhesive (Mitsui Chemicals, Inc., A-3210 / A-3075) was applied to the printed layer formation surface as an anchor coating agent to form a 0.3 μm thick anchor coating layer. In this way, a laminate consisting of the uniaxially oriented film (B), the vapor-deposited film, the barrier coating layer, the printed layer, and the anchor coating layer was obtained. The anchor coat layer of the laminate is made of LDPE (density: 0.918 g / cm³). 3 A laminate was obtained by melt-extruding (melting point: 106°C, MFR: 7.0 g / 10 min, manufactured by Nippon Polyethylene Co., Ltd., product name: Novatec LC600A) to an extruded resin layer thickness of 15 μm, while sand-laminating the laminate with an unstretched LLDPE film.

[0245] [Examples 2-3] A laminate was obtained in the same manner as in Example 2-2, except that a 20 nm thick alumina vapor-deposited film was formed by PVD instead of a 20 nm thick carbon-containing silicon oxide vapor-deposited film by CVD.

[0246] [Comparative Example 2-1] A uniaxially oriented film (B) and an unstretched LLDPE film with a thickness of 30 μm (Mitsui Chemicals Tohcello Co., Ltd., TUX-TCS) were prepared. A 20 nm thick aluminum vapor-deposited film was formed on the corona-treated surface of the uniaxially oriented film (B) by PVD. A 1 μm thick printed layer was formed on the aluminum vapor-deposited film by flexographic printing using an aqueous flexographic ink (Toyo Ink Co., Ltd., product name: Aquariona). In this way, a laminate consisting of the uniaxially oriented film (B), the vapor-deposited film, and the printed layer was obtained. The printed layer surface of the laminate and the corona-treated surface of the unstretched LLDPE film were bonded together via a 4 μm thick adhesive layer made of a two-component curing polyurethane adhesive (Rock Paint Co., Ltd., RU-77T / H-7) to obtain a laminate.

[0247] [Comparative Example 2-2] A uniaxially oriented film (B) and an unstretched LLDPE film with a thickness of 40 μm (Mitsui Chemicals Tohcello Co., Ltd., TUX-TCS) were prepared. A carbon-containing silicon oxide vapor-deposited film with a thickness of 20 nm was formed on the corona-treated surface of the uniaxially oriented film (B) by CVD. The prepared barrier coating agent was applied to the vapor-deposited film to form a barrier coating layer with a thickness of 300 nm. A printed layer with a thickness of 1 μm was formed by flexographic printing on the barrier coating layer using an aqueous flexographic ink (Toyo Ink Co., Ltd., product name: Aquariona). In this way, a laminate consisting of the uniaxially oriented film (B), the vapor-deposited film, the barrier coating layer, and the printed layer was obtained. The printed layer surface of the laminate and the corona-treated surface of the unstretched LLDPE film were bonded together via a 4 μm thick adhesive layer made of a two-component curing polyurethane adhesive (Rock Paint Co., Ltd., RU-77T / H-7) to obtain a laminate.

[0248] [Comparative Example 2-3] A laminate was obtained in the same manner as in Comparative Example 2-2, except that a 20 nm thick alumina vapor-deposited film was formed by PVD instead of a 20 nm thick carbon-containing silicon oxide vapor-deposited film by CVD.

[0249] [Method for measuring seal strength] Using two of each laminate produced in the examples and comparative examples, the sealant layers of the laminates were heat-sealed under the conditions of a temperature of 140°C and a pressure of 1 kgf / cm 2 for 1 second to form a seal portion. Subsequently, a portion including the seal portion was cut out to prepare a test piece with a width of 15 mm and a length of 100 mm for measuring the seal strength. The length of the seal portion was 15 mm. The seal strength was measured in accordance with JIS K7127:1999 under the condition of a test speed of 300 mm / min. As the measuring instrument, a tensile tester: SA-1150 manufactured by Orientec was used.

[0250] [Methods for measuring oxygen permeability and water vapor permeability] The laminate obtained above was cut out to obtain a test piece. Using this test piece, the oxygen permeability (cc / m 2 ·day·atm) and the water vapor permeability (g / m 2 ·day) were measured by the following method.

[0251] Using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON), the test piece was set so that the stretched substrate side of the test piece was the oxygen supply side, and the oxygen permeability under the environment of a temperature of 23°C and a relative humidity of 65%RH was measured in accordance with JIS K7126-2.

[0252] Using a water vapor permeability measuring device (PERMATRAN-w 3 / 33 manufactured by MOCON), the test piece was set so that the stretched substrate side of the test piece was the water vapor supply side, and the water vapor permeability under the environment of a temperature of 40°C and a relative humidity of 90%RH was measured in accordance with JIS K7129.

[0253] [Table 1]

[0254] [Table 2] [Explanation of Symbols]

[0255] 1: Laminate 10: Stretched base material 12: Base material layer 14: Adhesive resin layer 16: Functional resin layer 18: Vapor-deposited film 19: Barrier Coat Layer 20: Extruded resin layer 22: Anchor coat layer 30: Sealant layer 40: Standing Pouch 41: Torso (side sheet) 42: Bottom (bottom sheet) 43: Side gusset

Claims

1. A laminate comprising a stretched substrate and a sealant layer, The stretched substrate is A base layer containing polyethylene as the main component, Functional resin layer and Equipped with, The sealant layer contains polyethylene as its main component, The laminate comprises an extruded resin layer containing polyethylene as the main component between the stretched substrate and the sealant layer. Laminated structure.

2. The laminate according to claim 1, wherein the functional resin layer is a gas barrier resin layer or a heat-resistant resin layer.

3. The laminate according to claim 1 or 2, wherein the stretched substrate further comprises an adhesive resin layer between the substrate layer and the functional resin layer.

4. The laminate according to any one of claims 1 to 3, wherein the stretched substrate is a substrate that has undergone uniaxial stretching or biaxial stretching.

5. The laminate according to any one of claims 1 to 4, further comprising a vapor-deposited film formed on the surface of the sealant layer side of the stretched substrate.

6. The laminate according to any one of claims 1 to 5, further comprising a printed layer on the surface of the stretched substrate that is on the sealant layer side.

7. The laminate according to any one of claims 1 to 6, wherein the laminate further comprises an anchor coat layer between the stretched substrate and the extruded resin layer, and the extruded resin layer is in contact with the anchor coat layer.

8. The laminate according to any one of claims 1 to 7, wherein the thickness of the sealant layer is 20 μm or more and 60 μm or less.

9. The laminate according to any one of claims 1 to 8, wherein the polyethylene content is 90% by mass or more of 100% by mass of the laminate.

10. A laminate according to any one of claims 1 to 9, used for packaging material applications.

11. A packaging material comprising a laminate according to any one of claims 1 to 10.

12. A packaging container comprising a laminate according to any one of claims 1 to 10.

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