JP7828563B2 - Laminates, packaging materials, packaging bags and stand-up pouches - Google Patents

Description

This invention relates to a laminate, a packaging material composed of the laminate, a packaging bag, and a stand-up pouch.

Traditionally, packaging materials have been manufactured using resin films made from resin materials. For example, resin films made from polyethylene are widely used in packaging materials because they possess moderate flexibility, transparency, and excellent heat-sealability.

Typically, resin films made from polyethylene are inferior in terms of strength and heat resistance, and therefore cannot be used as a base material. Instead, they are used in combination with resin films made from polyester, polyamide, etc. For this reason, typical packaging materials consist of laminated films where the base material and the heat-seal layer are made of different resin materials (for example, Patent Document 1).

In recent years, with the growing demand for a circular economy, there has been a need for packaging materials with high recyclability. However, conventional packaging materials, as mentioned above, are composed of different types of resin materials, making it difficult to separate them individually, and therefore, they are not currently recycled.

Japanese Patent Publication No. 2009-202519

The inventors have found that polyethylene, which was conventionally used as a heat-seal layer, can be used as a base material by making it into a stretched film, and that by laminating this base material with a heat-seal layer made of polyethylene, it is possible to produce packaging materials that have sufficient strength and heat resistance and are also recyclable.
Furthermore, we have found that by further providing a vapor-deposited film in the laminate of the present invention, it is possible to produce packaging materials and the like that have excellent barrier properties, particularly oxygen barrier properties and water vapor barrier properties, while maintaining their recyclability.

This invention has been made in view of the above findings, and the problem it aims to solve is to provide a laminate that can realize a packaging material that has sufficient strength, heat resistance and barrier properties suitable for use as a packaging material, and is also excellent in terms of recyclability.
Furthermore, the problem that the present invention aims to solve is to provide a packaging material composed of the laminate.
Furthermore, the problem that the present invention aims to solve is to provide a packaging bag made from the laminate.
Furthermore, the problem that the present invention aims to solve is to provide a stand pouch made from the laminate.

In the first embodiment of the present invention, the laminate comprises a substrate, an adhesive layer, and a heat seal layer.
The base material and heat seal layer are made of polyethylene.
A vapor-deposited film is provided between the substrate and the adhesive layer, and between the heat seal layer and the adhesive layer,
The base material is characterized by being a stretched film made of polyethylene.

In a second embodiment of the present invention, the laminate comprises a substrate, a first adhesive layer, an intermediate layer, a second adhesive layer, and a heat seal layer.
The base material, intermediate layer, and heat seal layer are made of polyethylene.
A vapor-deposited film is provided between the substrate and the first adhesive layer, between the first adhesive layer and the intermediate layer, and between the heat seal layer and the second adhesive layer.
The material is characterized in that the base material and intermediate layer consist of a stretched film made of polyethylene.

In one embodiment of the present invention, the vapor-deposited film is an aluminum vapor-deposited film.
The vapor-deposited film and the adjacent adhesive layer are composed of a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphate-modified compound.

In one embodiment of the present invention, the substrate comprises a medium-density polyethylene layer.

In one embodiment of the present invention, the substrate has a structure consisting of a three-layer co-extruded film comprising a high-density polyethylene layer, a medium-density polyethylene layer, and another high-density polyethylene layer.

In one embodiment of the present invention, the polyethylene content in the entire laminate is 90% by mass or more.

In one embodiment of the present invention, the laminate is used for packaging material applications.

The packaging material of the present invention is characterized by being manufactured using the above-described laminate.

The packaging bag of the present invention is made using the above laminate,
The thickness of the heat seal layer is between 20 μm and 60 μm.

The stand pouch of the present invention is manufactured using the above laminate,
The thickness of the heat seal layer is between 50 μm and 200 μm.

According to the present invention, it is possible to provide a laminate that has strength, heat resistance, and barrier properties as a packaging material, and also exhibits excellent recyclability.

This is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. This is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. This is a schematic cross-sectional view showing one embodiment of the laminate of the present invention. This is a perspective view showing one embodiment of a packaging material made using the laminate of the present invention. This is a perspective view showing one embodiment of a packaging material made using the laminate of the present invention.

<Laminated structure>
The laminate according to the present invention will be described with reference to the drawings.
In a first embodiment of the present invention, as shown in Figures 1 and 2, the laminate 10 comprises a base material 11, an adhesive layer 12, and a heat-seal layer 13, and a vapor-deposited film 14 is provided between the base material 11 and the adhesive layer 12, and between the heat-seal layer 13 and the adhesive layer 12.

Furthermore, in a second embodiment of the present invention, as shown in Figure 2, the laminate 10 comprises a base material 11, an adhesive layer 12, an intermediate layer 15, a second adhesive layer 16, and a heat-seal layer 13, with a vapor-deposited film 14 provided at least in one of the following locations: between the base material 11 and the adhesive layer 12, between the adhesive layer 12 and the intermediate layer 15, and between the heat-seal layer 13 and the second adhesive layer 16.

In the laminate of the present invention, the polyethylene content is preferably 90% by mass or more.
By setting the polyethylene content in the entire laminate of the present invention to 90% by mass or more, the recyclability of the laminate of the present invention can be improved.
Furthermore, the polyethylene content in a laminate refers to the ratio of the polyethylene content to the sum of the resin material content in each layer constituting the laminate.

The following describes each layer constituting the laminate of the present invention.

<Base material>
The base material of the laminate of the present invention is made of polyethylene, and the heat-seal layer described below is also made of polyethylene. This configuration improves the recyclability of the laminate.

The substrate uses a stretched film made of polyethylene, which improves the heat resistance and strength of the laminate. It also improves the printability of the substrate.
The stretched film may be either a uniaxially oriented film or a biaxially oriented film.

The stretching ratio in the longitudinal direction (MD) of the stretched film is preferably 2 times or more and 10 times or less, and preferably 3 times or more and 7 times or less.
By setting the stretching ratio in the longitudinal direction (MD) of the stretched film to 2 times or more, the strength and heat resistance of the laminate of the present invention can be improved. Furthermore, the printability of the substrate can be improved. In addition, the transparency of the substrate can be improved, so when an image is formed on the heat-seal layer side surface of the substrate, its visibility can be improved. On the other hand, there is no particular upper limit to the stretching ratio in the longitudinal direction (MD) of the stretched film, but from the viewpoint of the breaking limit of the stretched film, it is preferable to set it to 10 times or less.

Furthermore, the stretching ratio in the transverse direction (TD) of the stretched film is preferably 2 times or more and 10 times or less, and preferably 3 times or more and 7 times or less.
By setting the stretching ratio in the transverse direction (TD) of the stretched film to 2 times or more, the strength and heat resistance of the laminate of the present invention can be improved. Furthermore, the printability of the substrate can be improved. In addition, the transparency of the substrate can be improved, so when an image is formed on the heat-seal layer side surface of the substrate, its visibility can be improved. On the other hand, there is no particular upper limit to the stretching ratio in the transverse direction (TD) of the stretched film, but from the viewpoint of the breaking limit of the stretched film, it is preferable to set it to 10 times or less.

The haze value of the stretched film is preferably 30% or less, and more preferably 20% or less. This improves the transparency of the stretched film.
In this invention, the haze value of the stretched film is measured in accordance with JIS K 7105.

The substrate may have an image formed on its surface.
It is preferable that an image be formed on the side where the heat seal layer described below is provided, as this prevents contact with the outside air and prevents deterioration over time.
The resulting images are not particularly limited and may represent letters, patterns, symbols, or combinations thereof.
Image formation on the substrate is preferably carried out using biomass-derived ink, which makes it possible to produce packaging materials with less environmental impact using the laminate of the present invention.
The method of image formation is not particularly limited and can include conventionally known printing methods such as gravure printing, offset printing, and flexographic printing. Among these, flexographic printing is preferred from the viewpoint of environmental impact.

The polyethylene used in the base material can be high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or very low-density polyethylene (VLDPE).
Here, high-density polyethylene can be polyethylene with a density of 0.945 g/ ^cm³ or higher, medium-density polyethylene can be polyethylene with a density of 0.925 g/ ^cm³ or higher and less than 0.945 g/ ^cm³ , low-density polyethylene can be polyethylene with a density of 0.900 g/ ^cm³ or higher and less than 0.925 g/ ^cm³ , linear low-density polyethylene can be polyethylene with a density of 0.900 g/ ^cm³ or higher and less than 0.925 g/ ^cm³ , and ultra-low-density polyethylene can be polyethylene with a density of less than 0.900 g/ ^cm³ .
Among these, high-density polyethylene and medium-density polyethylene are preferred from the viewpoint of printability, strength, and heat resistance of the laminate of the present invention, as well as stretchability of the film, and medium-density polyethylene is more preferred from the viewpoint of stretchability.

In one embodiment, a substrate can be configured to include a layer made of high-density polyethylene (hereinafter referred to as the high-density polyethylene layer) and a layer made of medium-density polyethylene (hereinafter referred to as the medium-density polyethylene layer).
By providing a high-density polyethylene layer on the outside of the base material, the strength and heat resistance of the laminate of the present invention can be further improved. Furthermore, by providing a medium-density polyethylene layer, the stretchability of the resin film constituting the base material can be further improved.

For example, it has a structure consisting of a co-extruded film of a high-density polyethylene layer and a medium-density polyethylene layer from the outside.
This configuration improves the stretchability of the film. Furthermore, it improves the strength and heat resistance of the laminate according to the present invention.
In this case, it is preferable that the thickness of the high-density polyethylene layer is thinner than the thickness of the medium-density polyethylene layer.
The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 1/10 or more and 1/1 or less, and more preferably 1/5 or more and 1/2 or less.
By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1/10 or more, the strength and heat resistance of the laminate of the present invention can be further improved. Furthermore, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1/1 or less, the stretchability of the resin film can be further improved.

Furthermore, for example, the structure can consist of a three-layer co-extruded film made of a high-density polyethylene layer, a medium-density polyethylene layer, and another high-density polyethylene layer from the outside inward.
This configuration improves the stretchability of the resin film. Furthermore, it improves the strength and heat resistance of the laminate of the present invention. Additionally, it prevents curling in the substrate.
In this case, it is preferable that the thickness of the high-density polyethylene layer is thinner than the thickness of the medium-density polyethylene layer.
The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 1/10 or more and 1/1 or less, and more preferably 1/5 or more and 1/2 or less.
By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1/10 or more, the strength and heat resistance of the laminate of the present invention can be further improved. Furthermore, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1/1 or less, the stretchability of the resin film can be further improved.

Furthermore, for example, the structure can also be a five-layer co-extruded film consisting of 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 (collectively referred to as a low-density polyethylene layer in this paragraph for simplification), a medium-density polyethylene layer, and a high-density polyethylene layer, from the outside in.
This configuration improves the stretchability of the film. Furthermore, it improves the strength and heat resistance of the laminate of the present invention. Additionally, it prevents curling in the substrate.
Furthermore, the production efficiency of the film can be improved as described below.
In this case, it is preferable that the thickness of the high-density polyethylene layer is thinner than the thickness of the medium-density polyethylene layer.
The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 1/10 or more and 1/1 or less, and more preferably 1/5 or more and 1/2 or less.
By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1/10 or more, the strength and heat resistance of the laminate of the present invention can be improved. Furthermore, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer to 1/1 or less, the stretchability of the film can be improved.
Furthermore, it is preferable that the thickness of the high-density polyethylene layer is the same as or greater than the thickness of the low-density polyethylene layer.
The ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer is preferably 1/0.25 or more and 1/2 or less, and more preferably 1/0.5 or more and 1/1 or less.
By setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer to 1/0.25 or more, heat resistance can be improved. Furthermore, by setting the ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer to 1/1 or less, the adhesion between the medium-density polyethylene layers can be improved.
In one embodiment, a substrate with such a configuration can be produced, for example, by an inflation method.
Specifically, it can be manufactured by co-extruding a high-density polyethylene layer, a medium-density polyethylene layer, and a low-density polyethylene layer, a linear low-density polyethylene layer, or an ultra-low-density polyethylene layer into a tube shape from the outside, and then pressing the opposing low-density polyethylene layers, linear low-density polyethylene layers, or ultra-low-density polyethylene layers together using a rubber roll or the like.
By manufacturing in this manner, the number of defective products in production can be significantly reduced, ultimately improving production efficiency.
Furthermore, the inflation film-forming machine can also perform stretching, which further improves production efficiency.

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

The single-site catalyst described above is a catalyst capable of forming a uniform active species, and is typically prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activation co-catalyst. Single-site catalysts are preferred over multi-site catalysts because their active site structure is more uniform, allowing for the polymerization of polymers with high molecular weight and high uniformity. Metallocene catalysts are particularly preferred as single-site catalysts. A metallocene catalyst is a catalyst comprising a transition metal compound of Group IV of the periodic table containing a ligand with a cyclopentadienyl skeleton, a co-catalyst, an organometallic compound as needed, and the catalyst components of a support.

In the transition metal compounds of Group IV of the periodic table containing the ligand having the cyclopentadienyl skeleton described above, the cyclopentadienyl skeleton is a cyclopentadienyl group, a substituted cyclopentadienyl group, etc. The substituted cyclopentadienyl group has at least one substituent selected from hydrocarbon groups having 1 to 30 carbon atoms, silyl groups, silyl-substituted alkyl groups, silyl-substituted aryl groups, cyano groups, cyanoalkyl groups, cyanoaryl groups, halogen groups, haloalkyl groups, halosilyl groups, etc. The substituted cyclopentadienyl group may have two or more substituents, and the substituents may bond to each other to form a ring, forming an indenyl ring, a fluorenyl ring, an azlenyl ring, or its hydrogenated form. The ring formed by the bonding of substituents may further have substituents on each other.

In a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, examples of the transition metal include zirconium, titanium, and hafnium, with zirconium and hafnium being particularly preferred. The transition metal compound typically has two ligands having a cyclopentadienyl skeleton, and it is preferable that each ligand is bonded to the others 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. A substituted silylene group is preferred. The above-described transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton can be used as a catalyst component, either individually or as a mixture of two or more.

As co-catalysts, we refer to those that can effectively utilize the transition metal compounds of Group IV of the periodic table as polymerization catalysts, or that can balance the ionic charge in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes and 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.

Transition metal compounds of Group IV of the periodic table containing ligands having a cyclopentadienyl skeleton may be used by being supported on an inorganic or organic compound. Preferred supports are porous oxides of inorganic or organic compounds, specifically including _ion -exchange layered silicates such as montmorillonite, _SiO₂ , _Al₂O₃ , MgO, _ZrO₂ , _TiO₂ , _B₂O₃ , CaO, ZnO, BaO, _ThO₂ , or mixtures thereof. Further organometallic compounds that may be used as needed include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Of these _, organoaluminum compounds are preferred.

Furthermore, copolymers of ethylene and other monomers can be used, as long as they do not impair the properties of the present invention. Examples of ethylene copolymers include copolymers consisting of ethylene and α-olefins having 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene. Also, copolymers with vinyl acetate or acrylic acid esters may be used, as long as they do not impair the objectives of the present invention.

Furthermore, in this invention, instead of ethylene obtained from fossil fuels, biomass-derived ethylene may be used as a raw material for obtaining the high-density polyethylene mentioned above. Since such biomass-derived polyethylene is a carbon-neutral material, it can be used as a packaging material with an even lower environmental impact. Such biomass-derived polyethylene can be manufactured, for example, by a method described in Japanese Patent Application Publication No. 2013-177531. Alternatively, commercially available biomass-derived polyethylene (for example, Green PE, commercially available from Braschem) may be used.

Furthermore, recycled polyethylene obtained through mechanical recycling can also be used. Mechanical recycling generally involves crushing collected polyethylene film, performing alkaline washing to remove dirt and foreign matter from the film surface, then drying it under high temperature and reduced pressure for a certain period to disperse any contaminants remaining inside the film, thereby decontaminating it and returning the polyethylene film to its original state.

The base material may contain additives to the extent that they do not impair the properties of the present invention. Examples include crosslinking agents, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins.

Furthermore, it is preferable that the substrate is surface-treated. This improves adhesion with adjacent layers.
The surface treatment method is not particularly limited and includes physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and/or nitrogen gas, glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals.
Alternatively, an anchor coat layer may be formed on the substrate surface using a conventionally known anchor coat agent.

The thickness of the substrate is preferably 10 μm or more and 50 μm or less, and more preferably 12 μm or more and 30 μm or less.
By making the substrate thickness 10 μm or more, the strength of the laminate of the present invention can be improved. Furthermore, by making the substrate thickness 50 μm or less, the processability of the laminate of the present invention can be improved.

The base material can be produced by forming a film from polyethylene using methods such as the T-die method or the inflation method, and then stretching the film.

When preparing a substrate using the T-die method, the polyethylene MFR is preferably 3 g/10 min or more and 20 g/10 min or less.
By setting the polyethylene MFR to 3 g/10 min or more, the processability of the laminate of the present invention can be improved. Furthermore, by setting the polyethylene MFR to 20 g/10 min or less, it is possible to prevent the resin film from rupturing.

When preparing a substrate by the inflation method, the MFR of polyethylene is preferably 0.5 g/10 min or more and 5 g/10 min or less.
By setting the polyethylene MFR to 0.5 g/10 min or more, the processability of the laminate of the present invention can be improved. Furthermore, by setting the polyethylene MFR to 5 g/10 min or less, the film-forming properties can be improved.

Furthermore, the base material is not limited to that prepared by the above method; commercially available materials may also be used.

<Adhesive layer>
In the first embodiment, the laminate of the present invention includes an adhesive layer between the substrate and the heat-seal layer or vapor-deposited film, and in the second embodiment, an adhesive layer is provided between the substrate and the intermediate layer, thereby improving the adhesion between these layers.
In the second embodiment, a second adhesive layer is provided between the intermediate layer and the heat-seal layer, and this can have the same configuration as the adhesive layer.

The adhesive layer contains at least one type of adhesive, which may be a one-component curing type, a two-component curing type, or a non-curing type adhesive. The adhesive may be a solvent-free type or a solvent-based type, but from the viewpoint of environmental impact, a solvent-free type adhesive is preferably used.
Examples of solvent-free adhesives include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, and urethane-based adhesives. Among these, two-component curing urethane-based adhesives are preferably used.
Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and olefin-based adhesives.

Furthermore, when an adhesive layer is provided adjacent to a vapor-deposited film, which is an aluminum vapor-deposited film, it is preferable that the adhesive layer be composed of a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphate-modified compound.
By configuring the adhesive layer in this way, the oxygen barrier and water vapor barrier properties of the laminate of the present invention can be further improved.
Furthermore, when applying laminates with vapor-deposited films to packaging materials, bending loads are applied to the laminate by molding machines, etc., which may cause cracks in the aluminum vapor-deposited film. By using the specific adhesives described above, even if cracks occur in the aluminum vapor-deposited film, the decrease in oxygen barrier properties and water vapor barrier properties can be suppressed.

Polyester polyols have two or more hydroxyl groups as functional groups in one molecule. Similarly, isocyanate compounds have two or more isocyanate groups as functional groups in one molecule.
Polyester polyols have, for example, a polyester structure or a polyester polyurethane structure as their main backbone.

As a specific example of a resin composition containing polyester polyol, isocyanate compound, and phosphate-modified compound, the PASLIM series sold by DIC Corporation can be used.

The resin composition may further contain plate-like inorganic compounds, coupling agents, cyclodextrins and/or their derivatives.

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

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

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

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

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

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

Furthermore, the compound may be a mixture of two or more compounds, including a compound in which one of R1, R2, or R3 is a group represented by general formula (2), a compound in which two of R1, R2, or R3 are groups represented by general formula (2), and a compound in which all of R1, R2, and R3 are groups represented by general formula (2).

X represents an arylene group selected from the group consisting of a 1,2-phenylene group, a 1,2-naphthylene group, a 2,3-naphthylene group, a 2,3-anthraquinonediyl group, and a 2,3-anthracenediyl group, which may have substituents.
If X is substituted by a substituent, it may be substituted by one or more substituents, and the substituent is bonded to any carbon atom on X that is different from the free radical. Examples of such substituents include chloro group, bromo group, methyl group, ethyl group, i-propyl group, hydroxyl group, methoxy group, ethoxy group, phenoxy group, methylthio group, phenylthio group, cyano group, nitro group, amino group, phthalimide group, carboxyl group, carbamoyl group, N-ethylcarbamoyl group, phenyl group, and naphthyl group.

In general formula (2), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, propylene group, butylene group, neopentylene group, 1,5-pentylene group, 3-methyl-1,5-pentylene group, 1,6-hexylene group, methylpentylene group, and dimethylbutylene group. Among these, propylene and ethylene groups are preferred, with ethylene being the most preferred.

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

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

Furthermore, examples of polyhydric alcohol components include alkylenediols with 2 to 6 carbon atoms. Examples include diols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol.

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

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

In general formula (3), the alkylene group represented by -(CH2)n1- may be linear or branched. n1 is preferably 2 or 3, with 2 being the most preferred.

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

If X is substituted by a substituent, it may be substituted by one or more substituents, and the substituent is bonded to any carbon atom on X that is different from the free radical. Examples of such substituents include chloro group, bromo group, methyl group, ethyl group, i-propyl group, hydroxyl group, methoxy group, ethoxy group, phenoxy group, methylthio group, phenylthio group, cyano group, nitro group, amino group, phthalimide group, carboxyl group, carbamoyl group, N-ethylcarbamoyl group, phenyl group, and naphthyl group.
The substituents of X are preferably a hydroxyl group, cyano group, nitro group, amino group, phthalimide group, carbamoyl group, N-ethylcarbamoyl group, and phenyl group, with the most preferred being a hydroxyl group, phenoxy group, cyano group, nitro group, phthalimide group, and phenyl group.

In general formula (4), Y represents an alkylene group having 2 to 6 carbon atoms, such as an ethylene group, propylene group, butylene group, neopentylene group, 1,5-pentylene group, 3-methyl-1,5-pentylene group, 1,6-hexylene group, methylpentylene group, and dimethylbutylene group. Among these, propylene and ethylene groups are preferred, with ethylene being the most preferred.

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

Furthermore, the mixture may consist of two or more compounds, including a compound in which one of R1, R2, or R3 is a group represented by general formula (4), a compound in which two of R1, R2, or R3 are groups represented by general formula (4), and a compound in which all of R1, R2, and R3 are groups represented by general formula (4).

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

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

Furthermore, examples of aromatic polycarboxylic acids or their anhydrides in which the carboxylic acid is substituted at the ortho position include orthophthalic acid or its anhydride, naphthalene 2,3-dicarboxylic acid or its anhydride, naphthalene 1,2-dicarboxylic acid or its anhydride, anthraquinone 2,3-dicarboxylic acid or its anhydride, and 2,3-anthracenecarboxylic acid or its anhydride. These compounds may have substituents on any carbon atom of the aromatic ring.

Examples of substituents include chloro group, bromo group, methyl group, ethyl group, i-propyl group, hydroxyl group, methoxy group, ethoxy group, phenoxy group, methylthio group, phenylthio group, cyano group, nitro group, amino group, phthalimide group, carboxyl group, carbamoyl group, N-ethylcarbamoyl group, phenyl group, and naphthyl group.

Furthermore, examples of polyhydric alcohol components include alkylenediols having 2 to 6 carbon atoms. Examples include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, and dimethylbutanediol.
In particular, polyester polyol compounds having an isocyanuric ring are preferred when 1,3,5-tris(2-hydroxyethyl)isocyanuric acid or 1,3,5-tris(2-hydroxypropyl)isocyanuric acid is used as the triol compound having an isocyanuric ring, an aromatic polycarboxylic acid in which the carboxylic acid is substituted at the ortho position or orthophthalic anhydride is used as the anhydride, and ethylene glycol is used as the polyhydric alcohol, as these compounds exhibit particularly excellent oxygen barrier properties and adhesion.

The isocyanuric ring is highly polar and trifunctional, and can increase the overall polarity of the system and increase the crosslinking density. From this perspective, it is preferable to contain 5% by mass or more of the isocyanuric ring relative to the total solid content of the adhesive resin.

Isocyanate compounds have two or more isocyanate groups in their molecule.
Furthermore, the isocyanate compound may be aromatic or aliphatic, and may be a low-molecular-weight compound or a high-molecular-weight compound.
Furthermore, the isocyanate compound may be a blocked isocyanate compound obtained by an addition reaction using a known isocyanate blocking agent by a known and conventional method.
In particular, polyisocyanate compounds having three or more isocyanate groups are preferred from the viewpoint of adhesion and retort resistance, and aromatic compounds are preferred from the viewpoint of oxygen barrier properties and water vapor barrier properties.

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

Phosphate-modified compounds are, for example, compounds represented by the following general formulas (5) or (6).
In general formula (5), R1, R2, and R3 are selected from a hydrogen atom, a C1-C30 alkyl group, a (meth)acryloyl group, an optionally substituted phenyl group, and a C1-C4 alkyl group having a (meth)acryloyloxy group, but at least one is a hydrogen atom, and n represents an integer from 1 to 4.
In the formula, R4 and R5 are groups selected from a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a (meth)acryloyl group, an optionally substituted phenyl group, and an alkyl group having 1 to 4 carbon atoms with a (meth)acryloyloxy group, where n is an integer from 1 to 4, x is an integer from 0 to 30, and y is an integer from 0 to 30, except when both x and y are 0.

More specifically, examples include phosphoric acid, pyrophosphate, triphosphate, methyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, dibutyl phosphate, 2-ethylhexyl acid phosphate, bis(2-ethylhexyl) phosphate, isododecyl acid phosphate, butoxyethyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, and polyoxyethylene alkyl ether phosphate. One or more of these can be used.

The content of the phosphate-modified compound in the resin composition is preferably 0.005% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 1% by mass or less.
By setting the content of the phosphate-modified compound to 0.005% by mass or more, the oxygen barrier properties and water vapor barrier properties of the laminate of the present invention can be improved. Furthermore, by setting the content of the phosphate-modified compound to 10% by mass or less, the adhesion of the adhesive layer can be improved.

The resin composition containing polyester polyol, isocyanate compound, and phosphate-modified compound may also contain plate-like inorganic compound, which can improve the adhesion of the adhesive layer. Furthermore, it can improve the bending load resistance of the laminate of the present invention.
Examples of plate-like inorganic compounds include kaolinite-serpentine clay minerals (haloysite, kaolinite, endelite, dickite, nacrite, antigorite, chrysotile, etc.) and pyrophyllite-talc group minerals (pyrophyllite, talc, kerolite, etc.).

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

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

Examples of titanium-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraoctyl bis(didodecyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) ethylene titanate, isopropyl trioctainol titanate, isopropyl dimethacrylate isostearoyl titanate, isopropyl isostearoyl diacrylic titanate, diisostearoylethylene titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumylphenyl titanate, and dicumylphenyl oxyacetate titanate.

Furthermore, specific examples of aluminum-based coupling agents include, for example, acetalkoxyaluminum diisopropylate, diisopropoxyaluminum ethyl acetacetate, diisopropoxyaluminum monomethacrylate, isopropoxyaluminum alkyl acetacetate mono(dioctyl phosphate), aluminum-2-ethylhexanoate oxide trimer, aluminum stearate oxide trimer, and alkyl acetacetate aluminum oxide trimer.

The resin composition may contain cyclodextrin and/or its derivatives, thereby improving the adhesion of the adhesive layer. Furthermore, the bending load resistance of the laminate of the present invention can be further improved.
Specifically, for example, cyclodextrins such as alkylated cyclodextrins, acetylated cyclodextrins, and hydroxyalkylated cyclodextrins, in which the hydrogen atom of the hydroxyl group of the glucose unit of a cyclodextrin is substituted with another functional group, can be used. Branched cyclic dextrins can also be used.
Furthermore, the cyclodextrin skeleton in cyclodextrins and cyclodextrin derivatives may be any of the following: α-cyclodextrin consisting of 6 glucose units, β-cyclodextrin consisting of 7 glucose units, or γ-cyclodextrin consisting of 8 glucose units.
These compounds may be used individually or in combination of two or more. Furthermore, these cyclodextrins and/or their derivatives may collectively be referred to as dextrin compounds from now on.

From the viewpoint of compatibility and dispersibility with resin compositions, it is preferable to use cyclodextrin derivatives as the cyclodextrin compound.

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

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

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

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

The adhesive layer can be formed by applying and drying it onto a substrate or other surface using conventionally known methods, such as the direct gravure roll coating method, gravure roll coating method, kiss coating method, reverse roll coating method, fontein method, and transfer roll coating method.

<Heat seal layer>
The heat-seal layer of the laminate of the present invention is characterized by being made of polyethylene, similar to the base material described above. This configuration makes it possible to produce packaging materials that have sufficient strength and heat resistance, and are also recyclable.
However, the intermediate layer is formed from an unstretched polyethylene resin film or from melt extrusion of polyethylene.

From the viewpoint of heat-sealability, the polyethylene constituting the heat-seal layer is preferably low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or very high-density polyethylene (VLDPE).
Copolymers of ethylene and other monomers can be used as long as they do not impair the properties of the present invention.
Furthermore, from an environmental perspective, it is preferable that the polyethylene be derived from biomass or recycled polyethylene.

The heat seal layer may contain the above-mentioned additives to the extent that it does not impair the properties of the present invention.

In one embodiment, the heat seal layer has a multilayer structure and includes an intermediate layer comprising at least one of medium-density polyethylene and high-density polyethylene.
Specifically, the structure can consist of a layer containing at least one of low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene; a layer containing at least one of medium-density polyethylene and high-density polyethylene; and a layer containing at least one of low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene.
By adopting this configuration, it is possible to further improve the suitability for bag making and strength of the laminate of the present invention while maintaining heat sealability.

The thickness of the heat-seal layer is preferably adjusted as appropriate according to the weight of the contents to be filled into the packaging material made from the laminate of the present invention.
For example, when preparing a packaging bag 20 as shown in Figure 4, which is filled with contents of 1 g or more and 200 g or less, the thickness of the heat seal layer is preferably 20 μm or more and 60 μm or less.
By making the heat seal layer 20 μm or thicker, it is possible to prevent the filled contents from leaking due to damage to the heat seal layer. Furthermore, by making the heat seal layer 60 μm or less, the processability of the laminate of the present invention can be improved.

Furthermore, for example, when manufacturing a stand pouch 30 as shown in Figure 5, which is filled with contents of 50 g or more and 2000 g or less, the thickness of the heat seal layer is preferably 50 μm or more and 200 μm or less.
By making the heat seal layer 50 μm or thicker, it is possible to prevent the filled contents from leaking due to damage to the heat seal layer. Furthermore, by making the heat seal layer 200 μm or less thick, the processability of the laminate of the present invention can be improved.
The shaded areas in Figures 4 and 5 represent the heat-sealed sections.

<Vaporized film>
In the first embodiment, the laminate of the present invention includes a vapor-deposited film between the substrate and the adhesive layer, and between the heat-seal layer and the adhesive layer, at least one of these. This improves the gas barrier properties of the laminate, specifically the oxygen barrier properties and the water vapor barrier properties.

Examples of vapor-deposited films include those composed of metals such as aluminum, as well as inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide.

Furthermore, 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 vapor-deposited film to 1 nm or more, the oxygen barrier and water vapor barrier properties of the laminate of the present invention can be further improved. Furthermore, by setting the thickness of the vapor-deposited film to 150 nm or less, the occurrence of cracks in the vapor-deposited film can be prevented, and the recyclability of the laminate of the present invention can be improved.

For the vapor-deposited film to be an aluminum vapor-deposited film, its OD value is preferably between 2 and 3.5. This allows for improved oxygen barrier and water vapor barrier properties while maintaining the productivity of the laminate of the present invention. In this invention, the OD value can be measured in accordance with JIS-K-7361.

Deposited films can be formed using conventionally known methods, such as physical vapor deposition (PVD) methods including vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods including plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition.

Furthermore, for example, a composite film consisting of two or more deposited films of different inorganic oxides can be formed and used by combining physical vapor deposition and chemical vapor deposition methods. The vacuum level of the deposition chamber is preferably about ^10⁻² to ^10⁻⁸ mbar before oxygen introduction, and preferably about ^10⁻¹ to ^10⁻⁶ mbar after oxygen introduction. The amount of oxygen introduced will vary depending on the size of the deposition machine. For the oxygen introduced, inert gases such as argon, helium, and nitrogen may be used as carrier gases within a range that does not cause problems. The film transport speed can be about 10 to 800 m/min.

The surface of the deposited film is preferably subjected to the above-mentioned surface treatment. This improves adhesion with adjacent layers.

<Middle class>
In a second embodiment of the present invention, the laminate comprises an intermediate layer, the intermediate layer being made of polyethylene, similar to the base material and heat-seal layer described above. This configuration improves the strength and heat resistance of the packaging material and makes it a recyclable packaging material.

The intermediate layer uses a stretched polyethylene film to further improve the strength and heat resistance of the packaging material. The stretched film may be either uniaxially oriented or biaxially oriented.

The stretching ratio in the longitudinal direction (MD) of the stretched film is preferably 2 times or more and 10 times or less, and preferably 3 times or more and 7 times or less.
By setting the stretching ratio in the longitudinal direction (MD) of the stretched film to 2 times or more, the strength and heat resistance of the laminate of the present invention can be improved. On the other hand, there is no particular upper limit to the stretching ratio in the longitudinal direction (MD) of the stretched film, but from the viewpoint of the breaking limit of the stretched film, it is preferable to set it to 10 times or less.

Furthermore, the stretching ratio in the transverse direction (TD) of the stretched film is preferably 2 times or more and 10 times or less, and preferably 3 times or more and 7 times or less.
By setting the stretching ratio in the transverse direction (TD) of the stretched film to 2 times or more, the strength and heat resistance of the laminate of the present invention can be improved. On the other hand, there is no particular upper limit to the stretching ratio in the transverse direction (TD) of the stretched film, but from the viewpoint of the breaking limit of the stretched film, it is preferable to set it to 10 times or less.

Among the polyethylenes mentioned above, high-density polyethylene and medium-density polyethylene are preferred as the polyethylene included in the intermediate layer from the viewpoint of strength, heat resistance, and suitability for stretching the film, and medium-density polyethylene is more preferred from the viewpoint of suitability for stretching.
Furthermore, the intermediate layer may also consist of the multilayer structure described above, similar to the base material.

The intermediate layer may contain the above-mentioned additives, to the extent that it does not impair the properties of the present invention.

The thickness of the intermediate layer is preferably 9 μm or more and 50 μm or less, and more preferably 12 μm or more and 30 μm or less.
By making the thickness of the intermediate layer 9 μm or more, the strength and heat resistance of the laminate of the present invention can be further improved. Furthermore, by making the thickness of the intermediate layer 50 μm or less, the processability of the laminate of the present invention can be improved.

The intermediate layer may be made using the T-die method or inflation method described above, or it may be a commercially available intermediate layer.

<Application>
The laminate of the present invention can be used particularly suitably for packaging material applications.
The packaging material is not particularly limited and may be a packaging bag 20 as shown in Figure 4, or a stand pouch 30 having a body 31 and a bottom 32 as shown in Figure 5. In the case of a stand pouch, only the body may be formed from the laminate, only the bottom may be formed from the laminate, or both the body and the bottom may be formed from the laminate.

The packaging bag can be manufactured by folding the laminated material in half and overlapping the two halves so that the heat-sealed layer faces inward, and then heat-sealing the edges.
Alternatively, the packaging bag can also be manufactured by overlapping two laminated materials so that the heat-seal layers face each other, and then heat-sealing the edges.

A stand-up pouch can be manufactured by first forming the body of the laminated material by heat-sealing it in a cylindrical shape with the heat-seal layer facing inward, and then folding the laminated material into a V-shape with the heat-seal layer facing inward, sandwiching it from one end of the body, and heat-sealing it to form the bottom.

The heat sealing method is not particularly limited and can be carried out using known methods such as bar seals, rotary roll seals, belt seals, impulse seals, high-frequency seals, and ultrasonic seals.

The contents to be filled into the packaging material are not particularly limited and may be liquids, powders, or gels. They may also be food products or non-food products.
After filling with contents, the opening can be heat-sealed to create a package.

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

<Example 1-1>
The above medium-density polyethylene was used to produce a film by inflation molding to obtain a polyethylene film with a thickness of 100 μm.
This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain a substrate A with a thickness of 20 μm. The haze value of substrate A was measured and found to be 6.5%.

An image was formed on one side of substrate A using the above-mentioned aqueous flexographic ink by flexographic printing.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared, and a 20 nm thick aluminum vapor-deposited film was formed on one side of it by PVD (Photovoltaic Damping).

The image-forming surface of substrate A and the vapor-deposited surface of the heat-seal layer were laminated together via the above-mentioned two-component curable urethane adhesive to obtain the laminate of the present invention.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 94% by mass.

<Example 1-2>
The above-mentioned high-density polyethylene and medium-density polyethylene were used to produce polyethylene films consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer. The thickness of the high-density polyethylene layer was 20 μm, and the thickness of the medium-density polyethylene layer was 60 μm.
This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times, and a base material B with a total thickness of 20 μm was obtained, with a high-density polyethylene layer thickness of 4 μm and a medium-density polyethylene layer thickness of 12 μm. The haze value of base material B was measured and found to be 8.9%.

An image was formed on one side of substrate B using the above-mentioned aqueous flexographic ink by flexographic printing.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared, and a 20 nm thick aluminum vapor-deposited film was formed on one side of it by PVD (Photovoltaic Damping).

The image-forming surface of substrate B and the vapor-deposited surface of the heat-seal layer were laminated together via the above-mentioned two-component curable urethane adhesive to obtain the laminate of the present invention.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 94% by mass.

<Examples 1 and 3>
The above-mentioned medium-density polyethylene was used to produce a film by inflation molding to obtain a polyethylene film with a thickness of 100 μm.
This polyethylene film was stretched in the longitudinal (MD) and widthwise (TD) directions at a stretching ratio of 2.24 times to obtain a substrate C with a thickness of 20 μm. The haze value of substrate C was measured and found to be 5.1%.

An image was formed on one surface of substrate C using the above-mentioned aqueous flexographic ink by flexographic printing.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared, and a 20 nm thick aluminum vapor-deposited film was formed on one side of it by PVD (Photovoltaic Damping).

The image-forming surface of the substrate C and the vapor-deposited film of the heat-seal layer were laminated together via the above-mentioned two-component curable urethane adhesive to obtain the laminate of the present invention.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 94% by mass.

<Example 1-4>
In Example 1-1, the laminate of the present invention was fabricated in the same manner as in Example 1-1, except that the image-forming surface of the substrate C and the vapor-deposited surface of the heat-seal layer were bonded using a two-component curing adhesive containing an isocyanate compound and a phosphate-modified compound (PASLIM VM001/VM102CP, manufactured by DIC Corporation).

<Comparative Example 1-1>
The above medium-density polyethylene was used to form a film by inflation molding to obtain a substrate e with a thickness of 20 μm. The haze value of substrate a was measured and found to be 23.5%.

An image was formed on one side of substrate a using the above-mentioned aqueous flexographic ink by flexographic printing.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared, and a 20 nm thick aluminum vapor-deposited film was formed on one side of it by PVD (Photovoltaic Damping).

The image-forming surface of substrate a and the vapor-deposited surface of the heat-seal layer were laminated together via the two-component curing urethane adhesive to obtain a laminate.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 94% by mass.

<Comparative Example 1-2>
The above-mentioned high-density polyethylene and medium-density polyethylene were formed into films by inflation molding to create a substrate b consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer. The thickness of each high-density polyethylene layer was 4 μm, and the thickness of the medium-density polyethylene layer was 12 μm. The haze value of substrate b was measured and found to be 28.8%.

An image was formed on one surface of substrate b using the above-mentioned aqueous flexographic ink by flexographic printing.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared, and a 20 nm thick aluminum vapor-deposited film was formed on one side of it by PVD (Photovoltaic Damping).

The image-forming surface of substrate b and the vapor-deposited surface of the heat-seal layer were laminated together via the two-component curing urethane adhesive to obtain a laminate.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 97% by mass.

<Comparative Example 1-3>
A laminate was obtained in the same manner as in Example 1-1, except that the base material A was a biaxially oriented polyester film with a thickness of 12 μm (Toyobo Co., Ltd., product name: E5100). The proportion of polyethylene in the laminate obtained in this manner was 71% by mass.

<Example 2-1>
The above-mentioned medium-density polyethylene was used to produce a film by inflation molding to obtain a polyethylene film with a thickness of 100 μm.
This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 to obtain a substrate D with a thickness of 20 μm. The haze value of substrate D was measured and found to be 6.5%.

An image was formed on one surface of substrate D using the above-mentioned aqueous flexographic ink by flexographic printing.

The above-mentioned medium-density polyethylene was fabricated using an inflation molding method to obtain a polyethylene film with a thickness of 100 μm. This film was then stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain an intermediate layer A with a thickness of 20 μm. Next, an aluminum vapor-deposited film with a thickness of 20 nm was formed on one side of the intermediate layer A by the PVD method.

The image-forming surface of substrate D was laminated onto the vapor-deposited surface of intermediate layer A via the two-component curing urethane adhesive. The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared and laminated to the non-deposited surface of intermediate layer A via the two-component curable urethane adhesive to obtain the laminate of the present invention.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 92% by mass.

<Example 2-2>
The above-mentioned high-density polyethylene and medium-density polyethylene were used to produce polyethylene films consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer. The thickness of the high-density polyethylene layer was 20 μm, and the thickness of the medium-density polyethylene layer was 60 μm.
This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times, and a substrate E with a total thickness of 20 μm was obtained, with a high-density polyethylene layer thickness of 4 μm and a medium-density polyethylene layer thickness of 12 μm. The haze value of substrate E was measured and found to be 8.9%.

An image was formed on one side of substrate E using the above-mentioned aqueous flexographic ink by flexographic printing.

The above-mentioned high-density polyethylene and medium-density polyethylene were used to produce polyethylene films consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer. The thickness of the high-density polyethylene layer was 20 μm, and the thickness of the medium-density polyethylene layer was 60 μm.
This polyethylene film was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times, and an intermediate layer B with a total thickness of 20 μm was obtained, with a high-density polyethylene layer thickness of 4 μm and a medium-density polyethylene layer thickness of 12 μm. Next, an aluminum vapor-deposited film with a thickness of 20 nm was formed on one side of intermediate layer B by the PVD method.

The image-forming surface of substrate E was laminated to the vapor-deposited surface of intermediate layer B via the two-component curing urethane adhesive. The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared and laminated to the non-deposited surface of the intermediate layer B via the two-component curable urethane adhesive to obtain the laminate of the present invention.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 92% by mass.

<Example 2-3>
The above medium-density polyethylene was used to produce a film by inflation molding to obtain a polyethylene film with a thickness of 100 μm.
This polyethylene film was stretched in the longitudinal (MD) and widthwise (TD) directions at a stretching ratio of 2.24 times to obtain a substrate F with a thickness of 20 μm. The haze value of the substrate F was measured and found to be 5.1%.

An image was formed on one surface of substrate F using the above-mentioned aqueous flexographic ink by flexographic printing.

The above medium-density polyethylene was used to produce a film by inflation molding to obtain a polyethylene film with a thickness of 100 μm.
This polyethylene film was stretched in the longitudinal (MD) and widthwise (TD) directions at a stretching ratio of 2.24 times to obtain an intermediate layer C with a thickness of 20 μm. Next, an aluminum vapor-deposited film with a thickness of 20 nm was formed on one side of the intermediate layer C by the PVD method.

The image-forming surface of substrate F was laminated onto the vapor-deposited surface of intermediate layer C via the two-component curing urethane adhesive. The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared and laminated to the non-deposited surface of the intermediate layer C via the two-component curable urethane adhesive to obtain the laminate of the present invention.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 92% by mass.

<Example 2-4>
In Example 2-1, the laminate of the present invention was fabricated in the same manner as in Example 4-1, except that the image-forming surface of the substrate D and the vapor-deposited surface of the intermediate layer A were bonded using a two-component curing adhesive containing an isocyanate compound and a phosphate-modified compound (PASLIM VM001/VM102CP, manufactured by DIC Corporation).

<Comparative Example 4-1>
The above medium-density polyethylene was used to form a film by inflation molding to obtain a substrate c with a thickness of 20 μm. The haze value of the substrate c was measured and found to be 23.5%.

An image was formed on one surface of substrate c using the above-mentioned aqueous flexographic ink by flexographic printing.

The above-mentioned medium-density polyethylene was fabricated using an inflation molding method to obtain an intermediate layer a with a thickness of 20 μm. Next, an aluminum vapor-deposited film with a thickness of 20 nm was formed on one surface of the intermediate layer a by the PVD method.

The image-forming surface of substrate c was laminated onto the vapor-deposited surface of intermediate layer a via the two-component curing urethane adhesive. The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared and laminated to the non-deposited surface of the intermediate layer a via the two-component curable urethane adhesive to obtain a laminate.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 92% by mass.

<Comparative Example 2-2>
The above-mentioned high-density polyethylene and medium-density polyethylene were formed into films by inflation molding to create a substrate d consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer. The thickness of each high-density polyethylene layer was 4 μm, and the thickness of the medium-density polyethylene layer was 12 μm. The haze value of the substrate d was measured and found to be 23.5%.

An image was formed on one surface of substrate d using the above-mentioned aqueous flexographic ink by flexographic printing.

The above-mentioned high-density polyethylene and medium-density polyethylene were formed into films by inflation molding to create an intermediate layer b consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer. The thickness of each high-density polyethylene layer was 4 μm, and the thickness of the medium-density polyethylene layer was 12 μm.
Next, an aluminum vapor-deposited film with a thickness of 20 nm was formed on one surface of the intermediate layer b by the PVD method.

The image-forming surface of substrate d was laminated to the vapor-deposited surface of intermediate layer b via the two-component curing urethane adhesive. The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.

As a heat-seal layer, an unstretched linear low-density polyethylene film with a thickness of 40 μm was prepared and laminated to the non-deposited surface of the intermediate layer b via the two-component curable urethane adhesive to obtain a laminate.
The thickness of the adhesive layer formed by the two-component curing urethane adhesive was 3.0 μm.
Furthermore, the proportion of polyethylene in the laminate obtained in this manner was 92% by mass.

<Comparative Example 2-3>
A laminate was obtained in the same manner as in Example 2-1, except that the base material and intermediate layer were changed to a 12 μm thick biaxially oriented polyester film (Toyobo Co., Ltd., product name: E5100). The proportion of polyethylene in the laminate obtained in this manner was 56% by mass.

<Recyclability Assessment>
The recyclability of the laminates obtained in the above examples and comparative examples was evaluated based on the following evaluation criteria. The evaluation results are summarized in Tables 1 and 2.
(Evaluation criteria)
○: The polyethylene content in the laminate was 90% by mass or more.
×: The polyethylene content in the laminate was less than 90% by mass.

<Heat resistance evaluation>
Two test pieces measuring 80 mm in length and 80 mm in width were prepared from the laminates obtained in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-2, as well as in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3.
Two test pieces were placed on top of each other with the heat-seal layers facing each other, and the three sides were heat-sealed at 140°C to create a packaging bag.
The prepared packaging materials were visually inspected and evaluated based on the following evaluation criteria. The evaluation results are summarized in Tables 1 and 2.
(Evaluation criteria)
○: No wrinkles or other defects were observed on the surface of the packaging material, and no adhesion to the heat seal bar was observed.
×: Wrinkles and other defects were present on the surface of the packaging material, and it was also found to be adhering to the heat seal bar, making it impossible to form bags.

<Printability Evaluation>
The images formed on the substrates of the laminates prepared in the above examples and comparative examples were visually observed and evaluated based on the following evaluation criteria. The evaluation results are summarized in Tables 1 and 2.
(Evaluation criteria)
○: The dimensional stability during printing was good, and a good image was formed without smudging or bleeding.
×: The film expanded and contracted during printing, resulting in smudging and blurring of the resulting image.

<Rigidity Evaluation>
The laminates prepared in the above examples and comparative examples were prepared as 10 mm wide test specimens, and their rigidity was measured using a loop stiffness tester (manufactured by Toyo Seiki Seisakusho, product name: Loop Stiffness Tester). The loop length was set to 60 mm. The measurement results are summarized in Tables 1 and 2.

<Strength Test>
The laminates prepared in the above examples and comparative examples were tested for their strength when pierced with a 0.5 mm diameter needle using a tensile testing machine (Orientec Co., Ltd., product name: RTC-1310A). The piercing speed was set to 50 mm/min. The measurement results are summarized in Tables 1 and 2.

<Flexural load resistance test>
First, the oxygen permeability and water vapor permeability of the laminates obtained in the above examples and comparative examples were measured.
For measuring oxygen permeability, a MOCON OXTRAN2/20 was used under conditions of 23°C and 90% RH. For measuring water vapor permeability, a MOCON PERMATRAN3/31 was used under conditions of 40°C and 90% RH.
Furthermore, the laminates obtained in the above examples and comparative examples were subjected to a bending load (stroke: 155 mm, bending motion: 440°) five times using a Gelboflex tester (manufactured by Tester Industries Co., Ltd., product name: BE1006BE) in accordance with ASTM F 392.
After bending, the oxygen and water vapor permeability of the laminate was measured.
Tables 1 and 2 show the oxygen and water vapor permeability of the laminate before and after the bending load test.

10: Laminate, 11: Substrate, 12: Adhesive layer, 13: Heat seal layer, 14: Vapor-deposited film, 15: Intermediate layer, 16: Second adhesive layer, 20: Packaging bag, 30: Stand-up pouch, 31: Body, 32: Bottom

Claims (7)

A laminate comprising at least a substrate, an adhesive layer, and a heat-seal layer,
The base material and the heat seal layer are made of polyethylene.
The polyethylene content in the entire laminate is 90% by mass or more.
A vapor-deposited film is provided between the heat seal layer and the adhesive layer.
The aforementioned substrate has a multilayer structure comprising a layer containing medium- density polyethylene , and consists of a stretched film with a haze value of 20% or less .
The stretching ratio of the stretched film in the longitudinal direction (MD) and/or transverse direction (TD) is 2 times or more and 7 times or less, respectively.
Printing is applied to at least one surface of the substrate.
The printed layer on the substrate contains medium- density polyethylene .
A laminate characterized in that the heat-seal layer comprises at least one selected from low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene. The aforementioned vapor-deposited film is an aluminum vapor-deposited film.
The laminate according to claim 1, wherein the adhesive layer adjacent to the vapor-deposited film is composed of a cured product of a resin composition containing a polyester polyol, an isocyanate compound, and a phosphate-modified compound. The laminate according to claim 1 or 2 , wherein the substrate is a three-layer co-pressed stretched film consisting of a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer. A laminate according to any one of claims 1 to 3 , used for packaging material applications. A packaging material made using a laminate according to any one of claims 1 to 4 . It is a packaging bag,
Made using the laminate described in any one of claims 1 to 4 ,
A packaging bag characterized in that the thickness of the heat-seal layer is 20 μm or more and 60 μm or less. It is a stand-up pouch,
Made using the laminate described in any one of claims 1 to 4 ,
A stand-up pouch characterized in that the thickness of the heat-seal layer is 50 μm or more and 200 μm or less.