JP7806411B2 - Vapor-deposited films, laminates, packaging materials and packaging containers - Google Patents

Description

This disclosure relates to vapor-deposited films, laminates, packaging materials, and packaging containers.

Films made of polyesters such as polyethylene terephthalate (hereinafter also referred to as "polyester films") have excellent mechanical properties, chemical stability, heat resistance, and transparency, and are inexpensive. For this reason, polyester films have traditionally been used as the substrate for laminates used in the production of packaging containers.

Depending on the contents filled into the packaging container, the packaging container may be required to have gas barrier properties such as oxygen barrier and water vapor barrier properties. To meet this requirement, a vapor-deposited film is formed on the surface of polyester film (Patent Document 1).

In recent years, research has been conducted into the use of resin substrates to replace polyester films as substrates for forming vapor-deposited films. From the perspective of recyclability, the use of polyolefin films, particularly polyethylene films, as such substrates has been considered.

Japanese Patent Application Laid-Open No. 2005-053223

The present inventors investigated the use of a polyolefin film as a resin substrate on which a vapor-deposited film is formed, instead of a conventional polyester film. As a result of their investigation, the present inventors discovered that gas barrier properties can be improved by forming a vapor-deposited film on the polyamide resin layer of a resin substrate comprising a polyolefin resin layer and a polyamide resin layer. The present inventors then investigated whether gas barrier properties could be further improved by adjusting the composition of the polyamide resin layer.

One problem that the present disclosure aims to solve is to provide a vapor-deposited film that has a resin substrate containing a polyolefin resin layer and a polyamide resin layer, and a vapor-deposited film, and that has excellent gas barrier properties.

The vapor-deposited film of the present disclosure comprises a resin substrate and a vapor-deposited film, the resin substrate comprising a polyolefin resin layer and a polyamide resin layer, the vapor-deposited film being provided on the polyamide resin layer, and the polyamide resin layer containing an aliphatic polyamide and a semi-aromatic polyamide.

The present disclosure provides a vapor-deposited film that has a resin substrate containing a polyolefin resin layer and a polyamide resin layer, and a vapor-deposited film, and that has excellent gas barrier properties.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the vapor-deposited film of the present disclosure. FIG. 2 is a schematic cross-sectional view showing one embodiment of the vapor-deposited film of the present disclosure. FIG. 3 is a schematic cross-sectional view showing one embodiment of the laminate of the present disclosure. FIG. 4 is a schematic cross-sectional view showing one embodiment of a laminate according to the present disclosure. FIG. 5 is a schematic cross-sectional view showing one embodiment of a laminate according to the present disclosure. FIG. 6 is a schematic top view showing a cut portion in a stretched film.

[Vapor-deposited film]
The vapor-deposited film of the present disclosure includes a resin substrate and a vapor-deposited film. The resin substrate includes a polyolefin resin layer and a polyamide resin layer. The vapor-deposited film is provided on the polyamide resin layer. In one embodiment, the resin substrate further includes an adhesive resin layer between the polyolefin resin layer and the polyamide resin layer.

In this disclosure, the term "film" is not intended to be particularly distinguished from "sheet."

Figure 1 shows one embodiment of a vapor-deposited film according to the present disclosure. The vapor-deposited film 1 shown in Figure 1 comprises a resin substrate 10 and a vapor-deposited film 20. The resin substrate 10 comprises a polyolefin resin layer 12 and a polyamide resin layer 14, in this order in the thickness direction. The vapor-deposited film 1 in Figure 1 comprises a polyolefin resin layer 12, a polyamide resin layer 14, and a vapor-deposited film 20, in this order in the thickness direction.

Figure 2 shows one embodiment of the vapor-deposited film of the present disclosure. The vapor-deposited film 1 shown in Figure 2 is similar to that shown in Figure 1, except that the resin substrate 10 further comprises an adhesive resin layer 13 between the polyolefin resin layer 12 and the polyamide resin layer 14. The vapor-deposited film 1 in Figure 2 comprises, in this order in the thickness direction, the polyolefin resin layer 12, the adhesive resin layer 13, the polyamide resin layer 14, and the vapor-deposited film 20.

In the embodiment of Figures 1 and 2, the vapor-deposited film 1 may further include a printed layer (not shown). The printed layer may be provided, for example, on the surface of the polyolefin resin layer 12 opposite to the surface facing the vapor-deposited film 20. The printed layer may be provided, for example, on the surface of the vapor-deposited film 20 opposite to the surface facing the polyolefin resin layer 12. In this case, a barrier coat layer (described below) may be provided between the vapor-deposited film 20 and the printed layer.

<Polyolefin resin layer>
The resin substrate includes a polyolefin resin layer.
The polyolefin resin layer contains a polyolefin. Examples of polyolefins include polyethylene, polypropylene, and polymethylpentene. Among these, polyethylene and polypropylene are preferred, and polyethylene is more preferred. That is, the polyolefin resin layer is preferably a polyethylene resin layer or a polypropylene resin layer, and more preferably a polyethylene resin layer.

In this disclosure, polyethylene refers to a polymer in which the content of ethylene-derived structural units among all repeating structural units is 50 mol% or more. 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.

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 2 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.

Specific examples of polyethylene include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene. Of these, high-density polyethylene and medium-density polyethylene are preferred from the viewpoint of the strength and heat resistance of the resin substrate, and medium-density polyethylene is more preferred from the viewpoint of stretchability.

The density of high-density polyethylene is preferably greater than 0.945 g/cm ^3. The upper limit of the density of high-density polyethylene is, for example, 0.965 g/cm ^3. The density of medium-density polyethylene is preferably greater than 0.925 g/cm ³ and not greater than 0.945 g/cm ^3. The density of low-density polyethylene is preferably greater than 0.900 g/cm ³ and not greater than 0.925 g/cm ^3. Low-density polyethylene is typically polyethylene obtained by polymerizing ethylene using a high-pressure polymerization method. The density of linear low-density polyethylene is preferably greater than 0.900 g/cm ³ and not greater than 0.925 g/cm ^3. Linear low-density polyethylene is typically polyethylene obtained by polymerizing ethylene and a small amount of α-olefin using a low-pressure polymerization method (e.g., a polymerization method using a Ziegler-Natta catalyst or a metallocene catalyst). The density of very low-density polyethylene is preferably 0.900 g/cm ³ or less. The lower limit of the density of the very low density polyethylene is, for example, 0.860 g/cm ^3. The density of polyethylene is measured in accordance with JIS K7112 (1999), particularly Method D (density gradient tube method, 23° C.).

From the viewpoint of film-forming properties and processability, the melt flow rate (MFR) of the polyethylene is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.3 g/10 min or more and 30 g/10 min or less, even more preferably 0.5 g/10 min or more and 10 g/10 min or less, and particularly preferably 0.5 g/10 min or more and 5.0 g/10 min or less. In this disclosure, the MFR of polyethylene is measured in accordance with ASTM D1238 at a temperature of 190°C and a load of 2.16 kg.

The melting point (Tm) of the polyethylene is preferably 100°C or higher and 140°C or lower, more preferably 110°C or higher and 138°C or lower, and even more preferably 120°C or higher and 135°C or lower. In this disclosure, Tm is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

The polypropylene may be a propylene homopolymer, a propylene random copolymer, or a propylene block copolymer. A propylene homopolymer is a polymer of propylene alone. A propylene random copolymer is a random copolymer of propylene and an ethylenically unsaturated monomer other than propylene (e.g., the above-mentioned α-olefins such as ethylene, 1-butene, and 4-methyl-1-pentene). A propylene block copolymer is a copolymer having a polymer block of propylene and a polymer block of an ethylenically unsaturated monomer other than propylene (e.g., the above-mentioned α-olefins such as ethylene, 1-butene, and 4-methyl-1-pentene). For example, it is preferable to use a homopolymer when the rigidity and heat resistance of the resin substrate are important, and a random copolymer when the impact resistance of the resin substrate is important.

In this disclosure, polypropylene refers to a polymer in which the content of propylene-derived structural units among all repeating structural units is 50 mol% or more. In this polymer, the content of propylene-derived structural units is preferably 70 mol% or more, and more preferably 80 mol% or more. The above content can be measured by NMR.

From the viewpoint of film-forming properties and processability, the MFR of polypropylene is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.3 g/10 min or more and 30 g/10 min or less. In this disclosure, the MFR of polypropylene is measured in accordance with ASTM D1238 at a temperature of 230°C and a load of 2.16 kg.

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

A single-site catalyst 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 activating cocatalyst. Compared to multi-site catalysts, single-site catalysts have a uniform active site structure, making them preferable because they can produce polymers with high molecular weights and highly uniform structures.

A metallocene catalyst is preferred as a single-site catalyst. A metallocene catalyst is a catalyst containing a transition metal compound of Group IV of the periodic table that contains a ligand having a cyclopentadienyl skeleton, a cocatalyst, optionally an organometallic compound, and optionally a support.

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

The cyclopentadienyl skeleton in the transition metal compound is a cyclopentadienyl group or a substituted cyclopentadienyl group. The substituted cyclopentadienyl group has at least one substituent selected from, for example, a hydrocarbon group having from 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. The substituted cyclopentadienyl group has one or more substituents, and the substituents may be bonded to each other to form a ring, such as an indenyl ring, a fluorenyl ring, an azulenyl ring, or a hydrogenated version thereof. The ring formed by bonding the substituents to each other may further have a substituent.

Transition metal compounds typically have two ligands having a cyclopentadienyl skeleton. The ligands having each cyclopentadienyl skeleton are preferably bonded to each other via a bridging group. Examples of bridging groups include alkylene groups having from 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.

A co-catalyst is a component that enables a transition metal compound of Group IV of the periodic table to function effectively as a polymerization catalyst, or a component that balances 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 a cation with or without an active hydrogen group and a non-coordinating anion, lanthanoid salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing a fluoro group.

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

The transition metal compound may be used by being supported on an inorganic or organic carrier, preferably an inorganic or organic porous oxide, such as montmorillonite or another ion-exchange layered silicate, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO ₂ , or a mixture thereof.

Biomass-derived polyolefins may be used as polyolefins. That is, biomass-derived olefins may be used as raw materials for obtaining polyolefins instead of olefins obtained from fossil fuels. Because biomass-derived polyolefins are carbon-neutral materials, they can reduce the environmental impact of packaging materials. Biomass-derived polyolefins (e.g., polyethylene) can be produced, for example, by the method described in JP 2013-177531 A. Commercially available biomass-derived polyolefins (e.g., Green PE, available from Braskem) may also be used.

Polyolefins recycled by mechanical or chemical recycling may be used as the polyolefin. This reduces the environmental impact of packaging materials. Mechanical recycling generally involves crushing recovered polyolefin films, washing them with alkali to remove dirt and foreign matter from the film surface, and then drying them at high temperature and reduced pressure for a certain period of time to diffuse contaminants remaining inside the film, thereby decontaminating the film and removing the dirt from the film, and returning it to polyolefin. Chemical recycling generally involves decomposing recovered polyolefin films to the monomer level and repolymerizing the monomers to obtain polyolefin.
The above description of polyolefins is applicable to the polyolefins in the following description.

The polyolefin resin layer can contain one or more types of polyolefins.
The polyolefin content in the polyolefin resin layer, for example, the polyethylene content or the polypropylene content, is 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, which can improve the recyclability of the resin substrate, for example.

The polyolefin resin layer may contain one or more additives. Examples of additives include crosslinking agents, antiblocking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins.

The polyolefin resin layer may have a single-layer structure or a multi-layer structure of two or more layers. In one embodiment, the number of polyolefin resin layers is two to seven, or three to five, specifically three, five, or seven. Having a multi-layer structure for the polyolefin resin layer can improve the balance between rigidity, strength, and heat resistance of the resin substrate, for example.

In one embodiment, each layer constituting the polyolefin resin layer having a multilayer structure is also composed of a polyolefin. That is, the polyolefin content in each layer, for example, the polyethylene content or polypropylene content, is 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. This can, for example, improve the recyclability of the resin substrate.

The thickness of the polyolefin resin layer before stretching is preferably 20 μm or more and 200 μm or less, more preferably 30 μm or more and 150 μm or less, and even more preferably 40 μm or more and 120 μm or less. The thickness of the polyolefin resin layer after stretching is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and even more preferably 10 μm or more and 30 μm or less. If the thickness of the polyolefin resin layer before or after stretching is equal to or greater than the lower limit, for example, the rigidity and strength of the resin substrate can be improved. If the thickness of the polyolefin resin layer before or after stretching is equal to or less than the upper limit, for example, the processability of the resin substrate can be improved.

<Polyamide resin layer>
The resin substrate includes a polyamide resin layer. By forming a vapor-deposited film on the polyamide resin layer, gas barrier properties can be improved compared to forming a vapor-deposited film on a polyolefin resin layer. The reason for this is unclear, but the present inventors speculate as follows: Polyamide has a polar structure called an amide bond. The main chains of adjacent polyamides attract each other through hydrogen bonds or the like, restricting the mobility of the polar structure. Therefore, gas barrier properties are improved. Note that the above explanation is merely speculation and does not limit the present disclosure in any way.

In one embodiment, the polyamide resin layer constitutes a surface resin layer (outermost layer) on one side of the resin substrate. This configuration can improve, for example, the processability and heat resistance of the resin substrate in addition to the gas barrier properties described above.

The polyamide resin layer contains an aliphatic polyamide and a semi-aromatic polyamide.
The polyamide resin layer may contain one or more aliphatic polyamides.
The polyamide resin layer may contain one or more semi-aromatic polyamides.

The content of polyamides, including aliphatic polyamides and semi-aromatic polyamides, in the polyamide resin layer is preferably greater than 50% by mass, more preferably at least 60% by mass, even more preferably at least 70% by mass, and particularly preferably at least 80% by mass, 85% by mass, 90% by mass, or 95% by mass.

Below, we will explain the raw material monomers from which the structural units contained in polyamides can be derived, and then we will explain specific polyamides. Raw material monomers include, for example, lactams, aminocarboxylic acids, diamines, and dicarboxylic acids. Polyamides can be obtained, for example, by ring-opening polymerization of lactams, polycondensation of aminocarboxylic acids, polycondensation of diamines and dicarboxylic acids, or combinations of these.

Examples of lactams include γ-butyrolactam, δ-valerolactam, ε-caprolactam, enantholactam, undecanelactam, and dodecanelactam. Of these, ε-caprolactam, enantholactam, undecanelactam, and dodecanelactam are preferred. The lactam has, for example, 4 to 12 carbon atoms.

Examples of aminocarboxylic acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Of these, 6-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid are preferred. The number of carbon atoms in the aminocarboxylic acid is, for example, 6 to 12.

Examples of diamines include aliphatic diamines such as aliphatic chain diamines and alicyclic diamines, as well as aromatic diamines. The aliphatic diamines have, for example, 2 to 20 carbon atoms, preferably 4 to 12 carbon atoms.

Examples of aliphatic chain diamines include aliphatic linear diamines and aliphatic branched diamines, such as ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,5-pentanediamine, 2-methyl-1,8-octanediamine, and 2,2,4-/2,4,4-trimethylhexamethylenediamine.

Examples of alicyclic diamines include 1,3-/1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, bis(4-aminocyclohexyl)propane, bis(3-methyl-4-aminocyclohexyl)methane, (3-methyl-4-aminocyclohexyl)propane, 1,3-/1,4-bis(aminomethyl)cyclohexane, 5-amino-2,2,4-trimethyl-1-cyclopentanemethylamine, 5-amino-1,3,3-trimethylcyclohexanemethylamine, norbornanedimethyleneamine, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane.

Among aliphatic diamines, aliphatic chain diamines are preferred, aliphatic linear diamines are more preferred, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, and dodecamethylenediamine are even more preferred, and hexamethylenediamine is particularly preferred.

Examples of aromatic diamines include phenylenediamines such as p-phenylenediamine and m-phenylenediamine; xylylenediamines such as p-xylylenediamine and m-xylylenediamine; tolylenediamines such as 2,4-tolylenediamine and 2,6-tolylenediamine; diaminonaphthalenes such as 1,4-diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene, and 2,6-diaminonaphthalene; 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, and 4,4'-diamino-3,3',5,5'-tetramethyl Diaminodiphenylmethane compounds such as diphenylmethane, 4,4'-diamino-3,3',5,5'-tetraethyldiphenylmethane, and 4,4'-diamino-3,3'-dimethyl-5,5'-diethyldiphenylmethane; and bis(aminophenyl)propane compounds such as 2,2'-bis(3-aminophenyl)propane, 2,2'-bis(4-aminophenyl)propane, 2,2'-bis(4-amino-3-methylphenyl)propane, 2,2'-bis(4-amino-3-ethylphenyl)propane, 2,2'-bis(4-amino-3,5-dimethylphenyl)propane, 2,2'-bis(4-amino-3,5-diethylphenyl)propane, and 2,2'-bis(4-amino-3-methyl-5-ethylphenyl)propane.

Among aromatic diamines, xylylenediamine is preferred, p-xylylenediamine and m-xylylenediamine are more preferred, and m-xylylenediamine is even more preferred.

Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as aliphatic chain dicarboxylic acids and alicyclic dicarboxylic acids, as well as aromatic dicarboxylic acids. The aliphatic dicarboxylic acids have, for example, 2 to 20 carbon atoms, preferably 6 to 12 carbon atoms.

Examples of aliphatic chain dicarboxylic acids include aliphatic linear dicarboxylic acids and aliphatic branched dicarboxylic acids, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and eicosanedioic acid.

Examples of alicyclic dicarboxylic acids include 1,3-/1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, and norbornanedicarboxylic acid.

Among aliphatic dicarboxylic acids, aliphatic chain dicarboxylic acids are preferred, aliphatic linear dicarboxylic acids are more preferred, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid are even more preferred, and adipic acid is particularly preferred.

Examples of aromatic dicarboxylic acids include phthalic acid compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid; naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; and diphenylmethanedicarboxylic acids such as diphenylmethane-2,4-dicarboxylic acid, diphenylmethane-3,3'-dicarboxylic acid, diphenylmethane-3,4'-dicarboxylic acid, and diphenylmethane-4,4'-dicarboxylic acid.

Among aromatic dicarboxylic acids, phthalic acid compounds are preferred, with isophthalic acid and terephthalic acid being more preferred.

Examples of polyamides include aliphatic polyamides and semi-aromatic polyamides.

Examples of aliphatic polyamides include aliphatic homopolyamides and aliphatic copolyamides. Aliphatic homopolyamides may be polyamides composed of one lactam or one aminocarboxylic acid, or polyamides composed of a combination of one aliphatic diamine and one aliphatic dicarboxylic acid. In this disclosure, the latter are also classified as homopolyamides. Aliphatic copolyamides may be polyamides composed of two or more monomers selected from lactams and aminocarboxylic acids, polyamides composed of a combination of lactams and/or aminocarboxylic acids with aliphatic diamines and aliphatic dicarboxylic acids, or polyamides composed of a combination of one or more aliphatic diamines with one or more aliphatic dicarboxylic acids (excluding the combination of one aliphatic diamine and one aliphatic dicarboxylic acid).

In the following examples, polyamide is also referred to as "PA."
Specific examples of aliphatic homopolyamides include polycaprolactam (PA6), polyenantholactam (PA7), polyundecane lactam (PA11), polylauryllactam (PA12), polyhexamethylene adipamide (PA66), polytetramethylene dodecamide (PA412), polypentamethylene azelamide (PA59), polypentamethylene sebacamide (PA510), polypentamethylene dodecamide (PA512), polyhexamethylene azelamide (PA69), polyhexamethylene sebacamide (PA610), polyhexamethylene dodecamide (PA612), poly Examples include nonamethylene adipamide (PA96), polynonameethylene azelamide (PA99), polynonameethylene sebacamide (PA910), polynonameethylene dodecamide (PA912), polydecamethylene adipamide (PA106), polydecamethylene azelamide (PA109), polydecamethylene decamide (PA1010), polydecamethylene dodecamide (PA1012), polydodecamethylene adipamide (PA126), polydodecamethylene azelamide (PA129), polydodecamethylene sebacamide (PA1210), and polydodecamethylene dodecamide (PA1212).

Specific examples of 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), caprolactam/amino Examples include undecanoic acid copolymer (PA6/11), caprolactam/lauryllactam copolymer (PA6/12), caprolactam/hexamethylenediaminoadipic acid/lauryllactam copolymer (PA6/66/12), caprolactam/hexamethylenediaminoadipic acid/hexamethylenediaminosebacic acid copolymer (PA6/66/610), and caprolactam/hexamethylenediaminoadipic acid/hexamethylenediaminododecanedicarboxylic acid copolymer (PA6/66/612).

The relative viscosity of the aliphatic polyamide is preferably 1.5 or more and 5.0 or less, more preferably 2.0 or more and 5.0 or less, and even more preferably 2.5 or more and 4.5 or less. 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 at 25°C.

As aliphatic polyamides, crystalline aliphatic polyamides such as PA6, PA11, PA12, PA66, PA610, PA612, PA6/66, and PA6/66/12 are preferred from the perspective of improving physical properties such as abrasion resistance, cold resistance, impact resistance, and oil resistance.

The melting point (Tm) of the crystalline aliphatic polyamide is preferably 170°C or higher and 300°C or lower, more preferably 170°C or higher and 250°C or lower, even more preferably 170°C or higher and 230°C or lower, and particularly preferably 170°C or higher and 220°C or lower, 180°C or higher and 215°C or lower, or 180°C or higher and 210°C or lower. In this disclosure, Tm is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121. If the Tm is low, for example, when polyethylene and polyamide are co-extruded to form a co-extruded resin film, the difference in melting points between the polyethylene and polyamide is small, thereby improving moldability.

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.

In polyamides composed of aromatic diamines and aliphatic dicarboxylic acids, the diamines do not all need to be aromatic diamines, and they may further contain structural units derived from aliphatic diamines. In polyamides composed of aliphatic diamines and aromatic dicarboxylic acids, the dicarboxylic acids do not all need to be aromatic dicarboxylic acids, and they may further contain structural units derived from aliphatic dicarboxylic acids. These polyamides may further contain structural units derived from lactams and/or aminocarboxylic acids.

Specific examples of 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), polyhexamethylene terephthalamide/polycaproamide copolymer (PA6I/6), and polyhexamethylene terephthalamide/polycaproamide copolymer (PA6T/6). Examples include lydodecaamide 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). Of these, PA6I/6T and PAMXD6 are preferred, with PA6I/6T being more preferred.

The melt volume rate (MVR) of the semi-aromatic polyamide is preferably 5 ^cm3 /10 min to 200 ^cm3 /10 min, more preferably 10 ^cm3 /10 min to 100 ^cm3 /10 min, and from the viewpoint of film formability, even more preferably 10 ^cm3 /10 min to 50 ^cm3 /10 min. MVR is measured in accordance with ISO 1133 at a temperature of 275°C and a load of 5 kg.

Semi-aromatic polyamides are preferred as gas barrier resins.
The semi-aromatic polyamide may be an amorphous semi-aromatic polyamide such as PA6I/6T, or a crystalline semi-aromatic polyamide such as PA6T, PA9T, PA6I, PAMXD6, etc. Among these, amorphous semi-aromatic polyamides are preferred from the viewpoints of gas barrier properties and transparency.

Amorphous polyamide refers to a polyamide that does not have a clear melting point. Specifically, this refers to a polyamide whose crystalline melting enthalpy ΔHm is 5 J/g or less, preferably 3 J/g or less, and more preferably 1 J/g or less. The crystalline melting enthalpy is determined by differential scanning calorimetry (DSC) in accordance with JIS K7121 and JIS K7122.

As the amorphous semi-aromatic polyamide, a semi-aromatic polyamide having two or more structural units derived from aromatic dicarboxylic acids is preferred, and a polyamide having structural units derived from isophthalic acid and terephthalic acid as dicarboxylic acid components and structural units derived from aliphatic diamines as diamine components (hereinafter also referred to as "polyamide (a)") is more preferred.

In polyamide (a), the proportion of structural units derived from isophthalic acid, out of 100 mol% of structural units derived from dicarboxylic acids, is preferably 40 mol% to 98 mol%, more preferably 50 mol% to 80 mol%, and the proportion of structural units derived from terephthalic acid is preferably 2 mol% to 60 mol%, more preferably 20 mol% to 50 mol%. The above proportions can be measured by NMR.

In polyamide (a), the total proportion of isophthalic acid-derived structural units and terephthalic acid-derived structural units, based on 100 mol% of dicarboxylic acid-derived structural units, is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more, 95 mol% or more, or 98 mol% or more. Polyamide (a) may optionally contain structural units derived from dicarboxylic acids other than isophthalic acid and terephthalic acid (e.g., adipic acid).

The polyamide (a) preferably has a structural unit derived from hexamethylenediamine as a diamine component. In the polyamide (a), the proportion of the structural unit derived from hexamethylenediamine in 100 mol% of the structural units derived from diamine is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, 95 mol% or more, or 98 mol% or more. The polyamide (a) may have a structural unit derived from a diamine other than hexamethylenediamine, as necessary.
The polyamide (a) is preferably PA6I/6T.

The glass transition temperature (Tg) of the amorphous semi-aromatic polyamide is, for example, 90°C or higher and 180°C or lower, preferably 95°C or higher and 160°C or lower, and more preferably 100°C or higher and 150°C or lower. Tg is determined by differential scanning calorimetry (DSC) in accordance with JIS K7121.

The polyamide resin layer contains an aliphatic polyamide as the polyamide. The aliphatic polyamide content in the polyamide resin layer is preferably greater than 50% by mass, more preferably at least 60% by mass, and even more preferably at least 70% by mass. The upper limit of the aliphatic polyamide content is, for example, 99%, 95%, or 90% by mass.

The polyamide resin layer contains an aliphatic polyamide and a semi-aromatic polyamide as a barrier modifier. This configuration can improve, for example, the gas barrier properties of the vapor-deposited film, specifically the oxygen barrier properties and water vapor barrier properties. While the reason for this is unclear, the present inventors speculate as follows: Polyamides contain amide bonds and are typically hydrophilic, which means they are humidity-dependent. For example, high humidity can reduce the gas barrier properties of polyamides. Semi-aromatic polyamides contain aromatic rings in addition to amide bonds. The stacking effect of the aromatic rings can narrow the intermolecular gap. Therefore, the addition of semi-aromatic polyamides improves gas barrier properties. Note that the above explanation is speculation and does not limit the present disclosure in any way.

The content of semi-aromatic polyamide in the polyamide resin layer is preferably 1 part by mass to 100 parts by mass, more preferably 5 parts by mass to 60 parts by mass, even more preferably 10 parts by mass to 50 parts by mass, and particularly preferably 15 parts by mass to 40 parts by mass, per 100 parts by mass of aliphatic polyamide. This configuration can improve, for example, gas barrier properties.

In one embodiment, the polyamide resin layer contains a crystalline aliphatic polyamide and an amorphous semi-aromatic polyamide. This configuration can improve, for example, the stretchability of the resin substrate, the surface smoothness of the resin substrate before and after stretching, the curl suppression of the stretched film (described below), and the gas barrier properties and gloss of the vapor-deposited film, as described below.

Adding an amorphous semi-aromatic polyamide to a polyamide resin layer can improve the stretchability of the resin substrate, for example. While the reason for this is unclear, the present inventors speculate as follows: In one embodiment, stretching is performed at a temperature at which the polyolefin resin layer (particularly the polyethylene resin layer) softens. The molecular chains of amorphous semi-aromatic polyamides are more mobile than those of crystalline aliphatic polyamides. In one embodiment, the glass transition temperature of amorphous semi-aromatic polyamides is close to the melting point region of polyethylene. Therefore, during stretching, the polyamide resin layer containing amorphous semi-aromatic polyamide easily conforms to the polyolefin resin layer. This improves stretchability. Note that the above explanation is speculation and does not limit the present disclosure in any way.

By adding an amorphous semi-aromatic polyamide to the polyamide resin layer, for example, the surface smoothness of the polyamide resin layer before stretching can be improved, and this surface smoothness can be further improved by stretching. As the surface smoothness improves, for example, the gloss of the vapor-deposited film can also be improved and reflective haze can be reduced.

The surface roughness (Ra) of the polyamide resin layer in the stretched film is preferably 12 nm or less, more preferably 1.0 nm to 10 nm, and even more preferably 2.0 nm to 8.0 nm or 2.0 nm to 7.5 nm. The surface roughness (Ra) is the arithmetic mean surface roughness (Ra) measured in accordance with JIS B0601:2013.

The 20° gloss of the vapor-deposited film is preferably 1660 GU or more, more preferably 1680 GU or more, and even more preferably 1690 GU or more. There is no particular upper limit to the 20° gloss, but it may be, for example, 1950 GU. 20° gloss is measured in accordance with JIS Z8741, with the center of the light-receiving angle set at 20° and the light-receiving angle width set at 0.9°. Gloss indicates the intensity of specularly reflected light from the surface of an object; a higher value indicates higher gloss.

The specular reflection peak (Rspec) of the vapor-deposited film is preferably 1430 GU or higher, more preferably 1450 GU or higher, and even more preferably 1470 GU or higher. The upper limit of the specular reflection peak is 2000 GU. The center of the light-receiving angle is 20°, and the light-receiving angle width is 0.2°. The specular reflection peak indicates glossiness over a narrower range than the glossiness mentioned above, and therefore makes it possible to capture the surface condition locally. The larger the specular reflection peak, the higher the glossiness.

The reflective haze of the vapor-deposited film is preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less. The lower limit of the reflective haze is preferably as low as possible, but may be, for example, 1, 3, 5, or 7. The reflective haze is measured at an incident angle of 20°±1.8° in accordance with ASTM E430, and is calculated as the ratio of the amount of specularly reflected light (20°±1.8°) to the amount of dispersed light at angles of 18.1°±1.8° and 21.9°±1.8°, which cause haze. The reflective haze indicates the degree of cloudiness of the surface condition.
Details of the conditions for measuring the above physical properties are described in the Examples section.

When a resin substrate has a polyamide resin layer as a surface resin layer on one side, the symmetry of the resin substrate in the thickness direction is reduced, which can cause curling in the stretched film. Here, adding an amorphous semi-aromatic polyamide to a polyamide resin layer containing a crystalline aliphatic polyamide can effectively suppress curling in the stretched film. While the reason for this is unclear, the present inventors speculate as follows: Because crystalline polyamide is a crystalline polymer, it undergoes significant volumetric shrinkage upon solidification. By blending a crystalline aliphatic polyamide with an amorphous semi-aromatic polyamide, this volumetric shrinkage can be suppressed. Furthermore, by blending a crystalline aliphatic polyamide with an amorphous semi-aromatic polyamide, the crystallinity and crystallization rate of the crystalline aliphatic polyamide can be adjusted. This is thought to lead to suppression of curling and improved smoothness and gloss. Note that the above explanation is merely speculation and does not limit the present disclosure in any way.

The content of amorphous semi-aromatic polyamide in the polyamide resin layer is preferably 1 part by mass to 100 parts by mass, more preferably 5 parts by mass to 60 parts by mass, even more preferably 10 parts by mass to 50 parts by mass, and particularly preferably 15 parts by mass to 40 parts by mass, per 100 parts by mass of crystalline aliphatic polyamide. This configuration can improve, for example, the physical properties described above.

In one embodiment, the polyolefin resin layer is a polyethylene resin layer containing polyethylene, and the polyamide resin layer contains a crystalline aliphatic polyamide. In the resin substrate, the difference (Tm1 - Tm2) between the melting point (Tm1) of the crystalline aliphatic polyamide contained in the polyamide resin layer and the melting point (Tm2) of the polyethylene contained in the polyethylene resin layer is preferably 90°C or less, more preferably 80°C or less, and even more preferably 75°C or less. This embodiment can improve the film-forming suitability, for example, when the resin substrate is produced by co-extrusion. The lower limit of this difference is, for example, 30°C, 40°C, or 50°C.

The polyamide resin layer may contain one or more additives. Examples of additives include crosslinking agents, antiblocking agents, slip agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins.

Examples of lubricants include hydrocarbon-based lubricants, fatty acid-based lubricants, fatty acid amide-based lubricants, ester-based lubricants, and metal soaps. Lubricants may be liquid or solid.

Examples of hydrocarbon-based lubricants include liquid paraffin, natural paraffin, polyethylene wax, and microcrystalline wax. Examples of fatty acid-based lubricants include stearic acid and lauric acid. Examples of fatty acid amide-based lubricants include stearic acid amide, palmitic acid amide, N-oleyl palmitic acid amide, behenic acid amide, erucic acid amide, arachidic acid amide, oleic acid amide, methylene bisstearamide, and ethylene bisstearamide. Examples of ester-based lubricants include butyl stearate, hydrogenated castor oil, ethylene glycol monostearate, and stearate monoglyceride. Examples of metal soaps include zinc stearate and calcium stearate.

The thickness of the polyamide resin layer before stretching is preferably 3 μm to 50 μm, more preferably 4 μm to 30 μm, and even more preferably 5 μm to 20 μm. The thickness of the polyamide resin layer after stretching is preferably 0.5 μm to 20 μm, more preferably 0.8 μm to 15 μm, and even more preferably 1.2 μm to 10 μm. When the thickness of the polyamide resin layer before or after stretching is equal to or greater than the lower limit, for example, the adhesion of the vapor-deposited film and the gas barrier properties of the vapor-deposited film can be improved, and the rigidity and strength of the resin substrate can be improved. When the thickness of the polyamide resin layer before or after stretching is equal to or less than the upper limit, for example, the processability of the resin substrate can be improved.

The ratio of the thickness of the polyamide resin layer to the total thickness of the resin substrate is preferably 1% or more and 25% or less, more preferably 3% or more and 20% or less, and even more preferably 5% or more and 15% or less. This configuration can improve, for example, the adhesion of the vapor-deposited film and the gas barrier properties of the vapor-deposited film, and can also improve the recyclability of mono-material packaging materials produced using the resin substrate.

<Adhesive resin layer>
In one embodiment, the resin substrate includes an adhesive resin layer between the polyolefin resin layer and the polyamide resin layer, which can improve adhesion between the polyolefin resin layer and the polyamide resin layer, for example.

The adhesive resin layer is composed of, for example, an adhesive resin. Examples of adhesive resins include polyolefins, modified polyolefins, vinyl resins, polyethers, polyesters, polyurethanes, silicone resins, epoxy resins, and phenolic resins. Modified polyolefins include modified polyolefins, particularly acid-modified polyolefins. Modified polyolefins include, for example, graft-modified polyolefins with unsaturated carboxylic acids such as maleic acid and fumaric acid, or their acid anhydrides, esters, or metal salts. Among adhesive resins, modified polyolefins are preferred, with modified polyethylene and modified polypropylene being more preferred, from the viewpoint of obtaining a composition suitable for monomaterial packaging materials.

From the viewpoint of film-forming properties and processability, the melt flow rate (MFR) of the modified polyolefin is preferably 0.1 g/10 min or more and 50 g/10 min or less, more preferably 0.3 g/10 min or more and 30 g/10 min or less, even more preferably 0.5 g/10 min or more and 10 g/10 min or less, and particularly preferably 0.5 g/10 min or more and 5.0 g/10 min or less.

The adhesive resin layer can contain one or more adhesive resins.
The adhesive resin layer has a thickness of, for example, 1 μm or more and 15 μm or less.

The ratio of the thickness of the adhesive resin layer to the total thickness of the resin substrate is preferably 1% or more and 25% or less, more preferably 3% or more and 20% or less, and even more preferably 5% or more and 15% or less. This configuration can improve the recyclability of mono-material packaging materials produced using the resin substrate, for example.

<Resin substrate>
In one embodiment, the resin substrate is a coextruded resin film, and each layer constituting the resin substrate is a coextruded resin layer. The resin substrate can be produced by film formation using, for example, an inflation method or a T-die method.

The total thickness of the resin substrate before stretching is preferably 30 μm or more and 300 μm or less, more preferably 40 μm or more and 250 μm or less, and even more preferably 50 μm or more and 200 μm or less. The total thickness of the resin substrate after stretching is preferably 6 μm or more and 80 μm or less, more preferably 10 μm or more and 60 μm or less, and even more preferably 12 μm or more and 50 μm or less.

In the present disclosure, before the vapor-deposited film is formed, the resin substrate comprising a polyolefin resin layer, and optionally an adhesive resin layer and a polyamide resin layer is preferably subjected to a stretching treatment. A resin substrate that has been stretched is also referred to as a "stretched film." Stretching the polyamide resin layer on which the vapor-deposited film is formed can improve, for example, the surface smoothness of the polyamide resin layer, and therefore the gloss of the vapor-deposited film.

Stretching can improve the heat resistance and strength of the resin substrate. Stretching may be uniaxial or biaxial, and in one embodiment, it is uniaxial. In one embodiment, the stretched film is a uniaxially stretched film, more specifically, a uniaxially stretched film that has been stretched in the machine direction (MD).

In one embodiment, the stretching ratio in the longitudinal direction (MD) of the stretched film 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 film is preferably 2 to 10 times, more preferably 3 to 7 times.

When the stretching ratio is 2x or more, for example, the rigidity, strength, and heat resistance of the resin substrate can be improved, and the transparency of the resin substrate can also be improved. When the stretching ratio is 10x or less, for example, good stretching can be carried out without causing breakage of the film.

Stretched films can be produced, for example, by forming a laminate from multiple resin materials or resin compositions using the inflation method or T-die method, and then stretching the resulting laminate. Stretching can improve the transparency, rigidity, strength, and heat resistance of the resin substrate. The inflation film-making machine can also stretch the laminate. This allows for the production of stretched films, thereby improving production efficiency.

In one embodiment, the stretched film is obtained by stretching a laminate (precursor) comprising a polyolefin resin layer, and optionally an adhesive resin layer and a polyamide resin layer. Specifically, the layers are co-extruded into a tubular shape to produce a laminate. By producing laminates using this method, the number of defective products can be reduced and production efficiency can be improved.

For example, when the polyolefin resin layer is a polyethylene resin layer and the resin substrate is produced by the T-die method, the melt flow rate (MFR) of the polyethylene constituting the polyethylene resin layer is preferably 3.0 g/10 min or more and 20 g/10 min or less, from the viewpoints of film-forming properties and processability.

For example, when the polyolefin resin layer is a polyethylene resin layer and the resin substrate is produced by an inflation method, the MFR of the polyethylene constituting the polyethylene resin layer is preferably 0.5 g/10 min or more and 5.0 g/10 min or less, from the viewpoints of film-forming properties and processability.

In one embodiment, the haze value of the stretched film is 20% or less, preferably 15% or less, and more preferably 13% or less. A smaller haze value is preferable, but in one embodiment, the lower limit may be 0.1%, 1%, or 3%. The haze value of the stretched film is measured in accordance with JIS K7136.

<Vapor-deposited film>
The vapor-deposited film of the present disclosure includes a vapor-deposited film on a polyamide resin layer, specifically on the surface of the polyamide resin layer opposite to the surface on which the polyolefin resin layer is provided, which can improve, for example, the gas barrier property, specifically the oxygen barrier property and water vapor barrier property, of the vapor-deposited film.

The vapor-deposited film may be composed of 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, and barium oxide. Among these, metal vapor-deposited films such as aluminum (Al) vapor-deposited films, and inorganic oxide vapor-deposited films such as aluminum oxide (alumina) vapor-deposited films and silicon oxide (silica) vapor-deposited films are preferred.

The thickness of the vapor-deposited film is preferably 1 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and even more preferably 10 nm or more and 40 nm or less. By making the thickness of the vapor-deposited film equal to or greater than the lower limit, for example, the oxygen barrier property and water vapor barrier property of the vapor-deposited film can be further improved. By making the thickness of the vapor-deposited film equal to or less than the upper limit, for example, the occurrence of cracks in the vapor-deposited film can be suppressed and the recyclability of the laminate can be improved.

Methods for forming vapor-deposited films include, for example, physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating; and chemical vapor deposition (CVD) methods such as plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. Vapor-deposited films may also be composite films containing two or more layers of vapor-deposited films of different inorganic oxides, formed using both physical vapor deposition and chemical vapor deposition.

The degree of vacuum in the deposition chamber is preferably about 10 ^-2 to 10 ^-8 mbar before oxygen is introduced, and about 10 ^-1 to 10 ^-6 mbar after oxygen is introduced. The amount of oxygen introduced varies depending on the size of the deposition machine, etc. Inert gases such as argon gas, helium gas, and nitrogen gas may be used as a carrier gas for the oxygen introduced, provided that this does not cause any problems. The conveying speed of the resin substrate on which the deposited film is formed is, for example, 10 m/min or more and 800 m/min or less.

The surface of the vapor-deposited film may be subjected to a surface treatment. This can improve adhesion between the vapor-deposited film and the layer adjacent to it, for example. Surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using gases such as oxygen gas and nitrogen gas, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals.

A barrier coating layer may be provided on the surface of the vapor-deposited film. With this configuration, for example, when the vapor-deposited film is composed of inorganic oxides such as aluminum oxide and silicon oxide, the gas barrier properties and printability of the vapor-deposited film can be effectively improved, and the occurrence of cracks in the vapor-deposited film can be effectively suppressed. In one embodiment, the vapor-deposited film of the present disclosure comprises, in this order in the thickness direction, a polyolefin resin layer, an adhesive resin layer (if necessary), a polyamide resin layer, a vapor-deposited film, and a barrier coating layer.

In one embodiment, the barrier coat layer is composed of a gas barrier resin. Examples of gas barrier resins include ethylene-vinyl alcohol copolymers; polyvinyl alcohol; polyacrylonitrile; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide; polyurethane; and polyvinylidene chloride.

The gas barrier resin content in the barrier coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. This configuration can, for example, improve the gas barrier properties of the barrier coat layer.

The thickness of the barrier coat layer is preferably 0.01 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less. By making the thickness of the barrier coat layer 0.01 μm or more, for example, the gas barrier properties can be further improved.

The barrier coat layer can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent, applying the resulting coating liquid, and drying it.

In another embodiment, the barrier coat layer is a gas barrier coating layer formed by mixing an alkoxide, a water-soluble polymer, and, if necessary, a silane coupling agent, and then adding water, an organic solvent, and a sol-gel catalyst to obtain a gas barrier composition, which is then applied to a vapor-deposited film and dried. The gas barrier coating layer contains a hydrolysis polycondensate obtained by hydrolyzing and polycondensing the alkoxide or the like by the sol-gel method. One or more of each of the above components can be used.

The alkoxide is represented by, for example, formula (1).
R ¹ _n M (OR ² ) _m (1)
In formula (1), ^R1 and ^R2 each independently represent an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the atomic valence of M.

Examples of the organic group in ^R1 and ^R2 include alkyl groups having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, an n-hexyl group, and an n-octyl group.
The metal atom M is, for example, silicon, zirconium, titanium or aluminum.

Examples of alkoxides represented by formula (1) include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

Examples of water-soluble polymers include water-soluble polymers having hydroxyl groups, such as 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 copolymers 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 together. The amount of water-soluble polymer used is preferably 5 to 500 parts by mass per 100 parts by mass of the alkoxide represented by formula (1).

The silane coupling agent can be a known organoalkoxysilane containing an organic reactive group, with organoalkoxysilanes containing an epoxy group being preferred, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The amount of silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the alkoxide represented by formula (1).

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

The sol-gel catalyst is preferably an acid or an amine compound.
Examples of the acid 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 the acid used is preferably 0.001 mol or more and 0.05 mol or less per 1 mol of the total molar amount of the alkoxide represented by formula (1) and the silane coupling agent.

Examples of amine compounds include N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. The amount of the amine compound used is preferably 0.01 to 1.0 parts by mass per 100 parts by mass of the alkoxide represented by formula (1) and the silane coupling agent combined.

Examples of methods for applying the gas barrier composition include roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, and applicator coating.

Hereinafter, one embodiment of the method for forming the gas barrier coating layer will be described.
A gas barrier composition is prepared by mixing an alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and, if necessary, a silane coupling agent. A polycondensation reaction gradually progresses within the composition. The composition is applied to a vapor-deposited film by a conventional method and dried. This drying further promotes polycondensation of the alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains one) to form a composite polymer layer. The above procedure may be repeated to laminate multiple composite polymer layers. The composition is heated at a temperature of preferably 20°C to 250°C, more preferably 50°C to 220°C, for example, 50°C to 120°C, for 1 second to 10 minutes. This allows the formation of a gas barrier coating layer.

The thickness of the gas barrier coating layer formed from a gas barrier composition using an alkoxide is preferably 0.01 μm or more and 100 μm or less, and more preferably 0.1 μm or more and 50 μm or less. This can improve gas barrier properties and suppress the occurrence of cracks in the vapor-deposited film, for example.

<Print layer>
In one embodiment, the vapor-deposited film of the present disclosure may include a printed layer.
The printed layer may be provided, for example, on the surface of the polyolefin resin layer opposite to the surface on the vapor-deposited film side. The printed layer may be provided, for example, on the surface of the vapor-deposited film opposite to the surface on the polyolefin resin layer side.

The printed layer includes, for example, an image. Examples of images include letters, figures, symbols, and combinations thereof. Methods for forming the printed layer include, for example, gravure printing, offset printing, and flexographic printing. In one embodiment, from the perspective of reducing the environmental impact, flexographic printing is preferred. Furthermore, from the perspective of reducing the environmental impact, the printed layer may be formed using ink derived from biomass.

[Laminate]
A laminate according to the present disclosure includes the vapor-deposited film according to the present disclosure and a heat-seal layer made of polyolefin. In one embodiment, the laminate according to the present disclosure further includes a substrate made of polyolefin on the side of the vapor-deposited film facing the heat-seal layer or on the side opposite to the side facing the heat-seal layer. In one embodiment, the heat-seal layer is a surface layer on one side of the laminate.

In this disclosure, the term "AAA composed of polyolefin" means that the main component of the AAA is polyolefin, but it is not limited to a configuration in which the AAA is composed solely of polyolefin. The AAA may contain components other than polyolefin. Specifically, the polyolefin content of the AAA 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, the term "AAA composed of polyethylene" means that the main component of the AAA is polyethylene, but it is not limited to a configuration in which the AAA is composed solely of polyethylene. The AAA may contain components other than polyethylene. Specifically, the polyethylene content of the AAA is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more.

For example, examples of polyethylene include high-density polyethylene and linear low-density polyethylene, 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.

The polyolefin content, for example, the polyethylene content or polypropylene content, in the entire laminate of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. Because such laminates use polyolefins, such as polyethylene or polypropylene, which are the same type of resin material, they can be classified as monomaterial materials and are suitable for use, for example, in the production of monomaterial packaging containers.

Figure 3 shows one embodiment of a laminate according to the present disclosure. The laminate 2 shown in Figure 3 comprises, in this order in the thickness direction, a vapor-deposited film 1 (resin substrate 10/vapor-deposited film 20), an adhesive layer 40, and a heat-seal layer 50 made of polyolefin. In this embodiment, the vapor-deposited film 1 may further comprise a printed layer (not shown). The printed layer may be provided, for example, on the polyolefin resin layer 12 of the vapor-deposited film 1. The printed layer may be provided, for example, on the vapor-deposited film 20 of the vapor-deposited film 1 (between the vapor-deposited film 20 and the adhesive layer 40), in which case the vapor-deposited film 20 is a transparent vapor-deposited film.

Figure 4 shows one embodiment of a laminate according to the present disclosure. The laminate 2 shown in Figure 4 comprises, in this order in the thickness direction, a substrate 30 made of polyolefin, an adhesive layer 40, a vapor-deposited film 1 (vapor-deposited film 20/resin substrate 10), an adhesive layer 40, and a heat-seal layer 50 made of polyolefin. The vapor-deposited film 20 of the vapor-deposited film 1 faces the substrate 30.

Figure 5 shows one embodiment of a laminate according to the present disclosure. The laminate 2 shown in Figure 5 comprises, in this order in the thickness direction, a vapor-deposited film 1 (resin substrate 10/vapor-deposited film 20), an adhesive layer 40, a substrate 30 made of polyolefin, an adhesive layer 40, and a heat-seal layer 50 made of polyolefin. The vapor-deposited film 20 of the vapor-deposited film 1 faces the substrate 30.

In one embodiment shown in Figures 4 and 5, the laminate 2 may further include a printed layer (not shown) on the substrate 30. The printed layer is formed, for example, on the surface of the substrate 30 facing the vapor-deposited film 1.

<Heat seal layer>
The laminate of the present disclosure comprises a heat seal layer.

The heat seal layer is composed of polyolefin, a resin material that can be fused to each other by heat. Examples of polyolefins include polyethylene, polypropylene, polybutene, and polymethylpentene. Specific examples include ethylene-α-olefin copolymers such as very low density polyethylene, low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-methyl(meth)acrylate copolymer, and ethylene-ethyl(meth)acrylate copolymer.

In one embodiment, the resin material constituting the heat seal layer is a polyolefin, which is the same type of resin material as the resin material constituting the polyolefin resin layer in the vapor-deposited film. A laminate having such a configuration can be suitably used as a laminate for producing a mono-material packaging container.
The heat seal layer may contain one or more polyolefins.

From the standpoint of heat sealability and recyclability, the heat seal layer is preferably composed of polyethylene or polypropylene, more preferably polyethylene, and examples of the polyethylene include ultra-low density polyethylene, low density polyethylene, and linear low density polyethylene. Details of polyolefins such as polyethylene and polypropylene are as explained in the section on the polyolefin resin layer, and will not be described here.

The polyethylene content in the heat seal 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, for example, improve the recyclability of the laminate.

From the standpoint of heat-sealability, the heat-seal layer is preferably an unstretched film. An unstretched film is a film that has not been stretched, such as an extruded film that has not been stretched. Details of the stretching process are as described above.

The heat seal layer may contain one or more of the above additives.
The heat seal layer may have a single layer structure or a multi-layer structure. In one embodiment, the number of layers of the heat seal layer is 2 to 7, for example, 3 to 7, or 3 to 5. In one embodiment, the number of layers of the heat seal layer is an odd number, for example, 3, 5, or 7.

The thickness of the heat seal layer is preferably 10 μm or more and 300 μm or less, more preferably 15 μm or more and 250 μm or less. From the standpoint of strength and processability, it is preferable to change the thickness of the heat seal layer appropriately depending on, for example, the mass of the contents to be placed in the packaging container.

<Base material>
The substrate is made of a polyolefin.
In one embodiment, the resin material constituting the substrate is a polyolefin, which is the same type of resin material as the resin material constituting the heat seal layer or the resin material constituting the polyolefin resin layer in the vapor-deposited film. A laminate having such a configuration can be suitably used as a laminate for producing a mono-material packaging container.

From the viewpoint of the recyclability of the packaging container, the substrate is preferably composed of polyethylene or polypropylene, more preferably polyethylene. Details of polyolefins such as polyethylene and polypropylene are as explained in the section on the polyolefin resin layer, and therefore will not be described here.
The substrate made of polyethylene will be specifically described below.

Examples of polyethylene include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene. From the viewpoint of the strength and heat resistance of the substrate, high-density polyethylene and medium-density polyethylene are preferred, and from the viewpoint of stretchability, medium-density polyethylene is preferred.

The substrate may contain one or more polyethylenes.
The content of polyethylene in the substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. Such a configuration can improve, for example, the recyclability of the laminate.

When the substrate has a multilayer structure, the polyethylene content in each layer constituting the substrate is independently 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, for example, improve the recyclability of the laminate.

The substrate 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. From the viewpoint of recyclability, it is particularly preferable that the substrate does not contain any resin materials other than polyethylene.
The substrate may contain one or more of the above additives.

The haze value of the substrate is preferably 25% or less, more preferably 15% or less, and even more preferably 10% 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.

The thickness of the substrate is preferably 10 μm or more and 60 μm or less, more preferably 15 μm or more and 50 μm or less. If the thickness of the substrate is 10 μm or more, for example, the rigidity and strength of the laminate can be improved. If the thickness of the substrate is 60 μm or less, for example, the processability of the laminate can be improved.

The substrate may have a single-layer structure or a multi-layer structure. Hereinafter, a substrate having a multi-layer structure will also be referred to as a "multi-layer substrate." Multi-layer substrates are preferred from the viewpoint of improving their strength, heat resistance, and stretchability.

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

In a multilayer substrate having a density gradient, the absolute value of the density difference between any two adjacent layers is preferably small. The absolute value of the density difference is preferably 0.040 g/cm ^or less, more preferably 0.030 g/cm ^or less, and even more preferably 0.020 g/cm ^or less. This configuration can effectively prevent, for example, delamination at the interface between the layers.

In the present disclosure, the density of each layer may be measured in accordance with JIS K7112 or calculated from the density of the components constituting the layer. For example, when a layer contains multiple components (e.g., polyethylene) with different densities (n types; n is an integer of 2 or more) the average density _Dav calculated according to the following formula (f1) may be used as the density of the layer.

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

The substrate is preferably subjected to a stretching treatment, and hereinafter such a substrate will also be referred to as a "stretched substrate." The substrate is more preferably a multilayer substrate that has been stretched. hereinafter such a substrate will also be referred to as a "stretched multilayer substrate." Stretching can improve the heat resistance and strength of the substrate, for example. Such stretched substrates, particularly stretched multilayer substrates, can satisfy the physical properties required for, for example, the outer layer of packaging materials.

Stretching 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.

When the stretching ratio is 2x 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. When the stretching ratio is 10x or less, for example, good stretching can be carried out without causing breakage of the film.

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

The stretched multilayer substrate has a multilayer structure of two or more layers. In one embodiment, the number of layers in the stretched multilayer substrate is from two to seven, for example, from three to seven, or from three to five. The number of layers in the stretched multilayer substrate is preferably an odd number, for example, three, five, or seven. The multilayer structure of the stretched multilayer substrate can improve the balance of the substrate's rigidity, strength, heat resistance, printability, and stretchability. Each layer of the stretched multilayer substrate is preferably composed of polyethylene.

The substrate, such as a stretched multilayer substrate, may be subjected to the surface treatment described above. This can, for example, improve adhesion between the substrate and the layer laminated thereon. An anchor coating layer may be formed on the surface of a substrate, such as a stretched multilayer substrate, using a conventional anchor coating agent.

Stretched multilayer substrates can be produced, for example, by forming a laminate from multiple resin materials or resin compositions using the inflation method or T-die method, and then stretching the resulting laminate. Stretching improves the transparency, rigidity, strength, and heat resistance of the substrate, making it suitable for use as a substrate for packaging materials, for example.

In one embodiment, the stretched multilayer substrate is obtained by stretching a laminate (precursor) having a multilayer structure. Specifically, the resin materials that make up each layer are co-extruded into a tubular shape to form a film, thereby producing a laminate. Alternatively, the resin materials that make up each layer are co-extruded into a tubular shape, and then the opposing layers are pressed together using a rubber roll or the like to produce a laminate. By producing laminates using this method, the number of defective products can be significantly reduced, and production efficiency can be improved.

For example, when the stretched multi-layer substrate is made of polyethylene and is manufactured using the T-die method, the melt flow rate (MFR) of the polyethylene constituting each layer of the multi-layer substrate is preferably 3 g/10 min or more and 20 g/10 min or less, from the viewpoints of film-forming properties and the processability of the multi-layer substrate.

For example, when the stretched multi-layer substrate is made of polyethylene and is manufactured by the inflation method, the MFR of the polyethylene constituting each layer of the multi-layer substrate is preferably 0.5 g/10 min or more and 5 g/10 min or less, from the viewpoints of film-forming properties and the processability of the multi-layer substrate.

A stretched multilayer substrate can be obtained, for example, by stretching the laminate described above. The preferred stretching ratio is as described above. Note that the laminate can also be stretched in an inflation film-making machine. This allows for the production of a stretched multilayer substrate, further improving production efficiency.

Below, several examples of embodiments of stretched multilayer substrates are described. Hereinafter, a layer containing 80% or more by weight of polyethylene will be referred to as a "polyethylene layer." For example, a layer containing 80% or more by weight of high-density polyethylene will be referred to as a "high-density polyethylene layer."

The stretched multilayer substrate of the first embodiment comprises, in this order in the thickness direction, a medium-density polyethylene layer, a high-density polyethylene layer, a blend layer of medium-density polyethylene and high-density polyethylene, a high-density polyethylene layer, and a medium-density polyethylene layer. This configuration can improve, for example, the printability of the substrate, its strength and heat resistance, and the stretchability of the pre-stretched laminate.

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

The stretched multilayer substrate of the second embodiment comprises, in this order 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 another medium-density polyethylene layer. This configuration can improve, for example, the printability of the substrate, its strength and heat resistance, and the stretchability of the pre-stretched laminate.

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

The stretched multilayer substrate of the third 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, in this order. This configuration can improve, for example, the printability of the substrate, its strength and heat resistance, and the stretchability of the pre-stretched laminate.

In the blend layers 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.

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

The stretched multilayer substrate of the fourth 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. This configuration can improve, for example, the printability of the substrate, its strength and heat resistance, and the stretchability of the pre-stretched laminate.

In the blend layers 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.

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.

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

In the stretched multilayer substrates of the first to fourth embodiments, the thickness of each of the two surface resin layers is preferably smaller than the total thickness of the three inner layers (multilayer intermediate layer). The ratio of the thickness of each of the two surface resin layers to the total thickness of the multilayer intermediate layer (surface resin layer/multilayer intermediate layer) is preferably 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 can further improve, for example, the rigidity, strength, and heat resistance of the substrate.

The stretched multilayer substrate of the fifth embodiment comprises a high-density polyethylene layer and a medium-density polyethylene layer in this order in the thickness direction. Having the surface resin layer of the substrate be a high-density polyethylene layer can improve, for example, the strength and heat resistance of the substrate. Having the substrate comprise a medium-density polyethylene layer can improve, for example, the stretchability of the pre-stretch laminate.

The stretched multilayer substrate of the sixth embodiment comprises a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer, in that order in the thickness direction. This configuration can, for example, improve the strength and heat resistance of the substrate, suppress curling in the substrate, and improve the stretchability of the pre-stretched laminate.

In the stretched multilayer substrates of the fifth and sixth embodiments, the thickness of the high-density polyethylene layer is preferably equal to or less than the thickness of the medium-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less.

The stretched multilayer substrate of the seventh embodiment comprises, in this order in the thickness direction, a high-density polyethylene layer, a medium-density polyethylene layer, a low-density polyethylene layer, a linear low-density polyethylene layer or an ultra-low-density polyethylene layer (for simplicity, these three layers are collectively referred to as the "low-density polyethylene layer, etc."), a medium-density polyethylene layer, and a high-density polyethylene layer. This configuration can, for example, improve the stretchability of the laminate before stretching, improve the strength and heat resistance of the substrate, and suppress curling in the substrate.

In the seventh embodiment of the stretched multilayer substrate, the thickness of the high-density polyethylene layer is preferably equal to or less than the thickness of the medium-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less.

In the stretched multilayer substrate of the seventh 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. is preferably 1 or more and 4 or less, more preferably 1 or more and 2 or less.

Other embodiments of the stretched multilayer substrate include a substrate comprising, in the thickness direction, 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 that order; and a substrate comprising, in the thickness direction, a medium-density polyethylene layer, a high-density polyethylene layer, a linear low-density polyethylene layer, a high-density polyethylene layer, and a medium-density polyethylene layer, in that order.

Another example is a substrate having, in the thickness direction, 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.

<Print layer>
In one embodiment, the laminate of the present disclosure further includes a printed layer formed on the above-described substrate. In one embodiment, the laminate of the present disclosure preferably includes a printed layer on the surface of the substrate facing the heat seal layer, because this can suppress deterioration of the image over time.

The printed layer includes, for example, an image. Examples of images include letters, figures, symbols, and combinations thereof. Methods for forming the printed layer include, for example, gravure printing, offset printing, and flexographic printing. In one embodiment, from the perspective of reducing the environmental impact, flexographic printing is preferred. Furthermore, from the perspective of reducing the environmental impact, the printed layer may be formed on the surface of the substrate using ink derived from biomass.

<Adhesive layer>
In one embodiment, the laminate of the present disclosure includes an adhesive layer between any layers, such as between the substrate and the vapor-deposited film, or between the substrate or the vapor-deposited film and the heat-sealing layer, thereby improving the adhesion between the substrate and the vapor-deposited film and between other layers.

The adhesive layer contains one or more types of adhesive. Examples of adhesives include one-component curing adhesives, two-component curing adhesives, and non-curing adhesives.

The adhesive may be a solvent-free adhesive or a solvent-based adhesive, and examples of the adhesive include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, urethane adhesives, rubber adhesives, vinyl adhesives, phenol adhesives, and olefin adhesives.
The adhesive layer may contain one or more of the above additives.

The thickness of the adhesive layer is preferably 0.5 μm or more and 10 μm or less, more preferably 0.8 μm or more and 8 μm or less, and even more preferably 1 μm or more and 6 μm or less. If the thickness of the adhesive layer is equal to or greater than the lower limit, for example, the adhesion between layers can be improved. If the thickness of the adhesive layer is equal to or less than the upper limit, for example, the recyclability of the packaging container can be improved.

The adhesive layer can be formed by applying an adhesive to the target using methods such as direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine coating, and transfer roll coating, and then drying as necessary.

[Application]
The vapor-deposited film or laminate of the present disclosure can be suitably used for packaging material applications. The packaging material is used to produce a packaging container. The packaging material comprises the laminate of the present disclosure. The packaging container can be produced by using at least a packaging material comprising the laminate of the present disclosure.

A packaging container comprises the vapor-deposited film or laminate of the present disclosure. Examples of packaging containers include packaging bags, tube containers, and containers with lids. A container with lid comprises a container body having a storage section and a lid material joined (heat sealed) to the container body so as to seal the storage section.

Heat sealing methods include, for example, bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, and ultrasonic sealing.

Packaging bags include various types, such as standing pouch, side seal, two-sided seal, three-sided seal, four-sided seal, envelope seal, palm seal (pillow seal), pleated seal, flat bottom seal, square bottom seal, and gusset seal.

The packaging bag may have an easy-to-open portion. Examples of easy-to-open portions include a notch portion 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 for tearing the packaging bag.

In one embodiment, a packaging bag can be produced by folding the laminate of the present disclosure in half and overlapping it so that the heat seal layer is located on the inside, and then heat-sealing the edges, etc. In another embodiment, a packaging bag can be produced by overlapping multiple laminates of the present disclosure so that the heat seal layers face each other, and then heat-sealing the edges, etc. The entire packaging bag may be made of the above-mentioned laminate, or only a portion of the packaging bag may be made of the above-mentioned laminate.

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

Contents that can be placed in a packaging container include, for example, liquids, solids, powders, and gels. The contents can be food or beverages, or non-food or beverages such as chemicals, cosmetics, and pharmaceuticals. The contents can be frozen foods or retort foods. After the contents are placed in the packaging container, the packaging container can be hermetically sealed by heat-sealing the opening of the packaging container.

The present disclosure relates to, for example, the following [1] to [15].
[1] A vapor-deposited film comprising a resin substrate and a vapor-deposited film, wherein the resin substrate comprises a polyolefin resin layer and a polyamide resin layer, the vapor-deposited film is provided on the polyamide resin layer, and the polyamide resin layer contains an aliphatic polyamide and a semi-aromatic polyamide.
[2] The vapor-deposited film according to the above [1], wherein the polyolefin resin layer is a polyethylene resin layer or a polypropylene resin layer.
[3] The vapor-deposited film according to the above [1] or [2], wherein the content of the aliphatic polyamide in the polyamide resin layer is more than 50% by mass and not more than 99% by mass.
[4] The vapor-deposited film according to any one of [1] to [3] above, wherein the content of the semi-aromatic polyamide in the polyamide resin layer is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the aliphatic polyamide.
[5] The vapor-deposited film according to any one of the above [1] to [4], wherein the aliphatic polyamide is a crystalline aliphatic polyamide having a melting point of 170°C or higher and 230°C or lower.
[6] The vapor-deposited film according to the above-mentioned [5], wherein the polyolefin resin layer is a polyethylene resin layer containing polyethylene, and the difference (Tm1 - Tm2) between the melting point (Tm1) of the crystalline aliphatic polyamide contained in the polyamide resin layer and the melting point (Tm2) of the polyethylene contained in the polyethylene resin layer is 90°C or less.
[7] The vapor-deposited film according to any one of the above [1] to [6], wherein the resin substrate further comprises an adhesive resin layer between the polyolefin resin layer and the polyamide resin layer.
[8] The vapor-deposited film according to any one of the above [1] to [7], wherein the resin substrate is a co-extruded resin film, and the vapor-deposited film is provided on a polyamide resin layer of the co-extruded resin film.
[9] The vapor-deposited film according to any one of the above [1] to [8], wherein the resin substrate is a stretched film, and the vapor-deposited film is provided on a polyamide resin layer of the stretched film.
[10] A laminate comprising the vapor-deposited film according to any one of [1] to [9] above and a heat-sealable layer made of polyolefin.
[11] The laminate according to the above [10], further comprising a substrate made of polyolefin on the surface of the vapor-deposited film on the side of the heat seal layer or on the surface opposite to the side of the heat seal layer.
[12] The laminate according to the above [11], wherein the polyolefin constituting the heat seal layer is polyethylene or polypropylene, and the polyolefin constituting the substrate is polyethylene or polypropylene.
[13] The laminate according to the above [11] or [12], further comprising a printed layer on a substrate made of polyolefin.
[14] A packaging material comprising the laminate according to any one of [10] to [13] above.
[15] A packaging container comprising the vapor-deposited film according to any one of [1] to [9] above, or the laminate according to any one of [10] to [13] above.

The vapor-deposited film of the present disclosure will be explained in more detail based on examples, but the vapor-deposited film of the present disclosure is not limited to these examples. Hereinafter, "parts by mass" will simply be referred to as "parts."

[Resin material]
The following resin materials were used:
Polyethylene A: ELITE 5538G, manufactured by Dow Chemical Company
Medium density polyethylene (MDPE), density: 0.941 g/cm ³ ,
Melting point: 129°C, MFR: 1.3g/10min. Nylon 6/66A: 5033B, manufactured by Ube Industries, Ltd.
Density: 1.14 g/cm ³ , melting point: 196°C,
Viscosity number: 249, relative viscosity: 4.05
Nylon 6/66B: Ultramid C40LN manufactured by BASF Corporation
Density: 1.12 g/cm ³ , melting point: 189°C,
Viscosity number: 250, relative viscosity: 4.0
Nylon 6/66C: Ultramid C33 manufactured by BASF Corporation
Density: 1.12 g/cm ³ , melting point: 196°C,
Viscosity number: 195, relative viscosity: 3.3
Barrier modifier A: manufactured by EMS
Grivory G21, an amorphous semi-aromatic polyamide;
Density: 1.18 g/cm ³ , glass transition temperature: 125°C,
MVR: 20 cm ³ /10 minutes / Adhesive resin A: Mitsui Chemicals, ADMER AT1955E,
Density: 0.89g/cm ³ , MFR: 2.6g/10min

[Example 1]
A five-layer coextrusion film was produced by inflation molding using a mixture of 80 parts nylon 6/66A and 20 parts barrier modifier A, adhesive resin A, polyethylene A, polyethylene A, and polyethylene A. The resulting film consisted of a 10 μm-thick polyamide resin layer (first resin layer, PA resin layer), a 10 μm-thick adhesive resin layer (second resin layer), and three 80 μm-thick polyethylene resin layers (third to fifth resin layers, PE resin layers). The film was stretched four times in the longitudinal direction (MD) to obtain a 25 μm-thick stretched film. The stretched film consisted of a 2.5 μm-thick polyamide resin layer, a 2.5 μm-thick adhesive resin layer, and three 20 μm-thick polyethylene resin layers.

A 30 nm thick Al vapor-deposited film was formed on the surface of the polyamide resin layer of the stretched film using the PVD method, resulting in a vapor-deposited film. The optical density (OD value) of the vapor-deposited film was measured and found to be 3.0.

[Examples 2 to 3 and Reference Examples 1 to 3]
Films, stretched films, and vapor-deposited films were obtained in the same manner as in Example 1, except that the blending composition of the polyamide resin layer, the thickness of each layer, and the stretching ratio were changed as shown in Table 1.

[Comparative Example 1]
A five-layer coextrusion film was formed using polyethylene A by inflation molding to obtain a 125 μm thick film consisting of five polyethylene resin layers (first to fifth resin layers). The film was stretched five times in the machine direction (MD) to obtain a 25 μm thick stretched film.

A 30 nm thick Al vapor-deposited film was formed on the polyethylene resin layer of the stretched film using the PVD method, resulting in a vapor-deposited film. The optical density (OD value) of the vapor-deposited film was measured and found to be 3.0.

[Evaluation method]
<Optical density>
The optical density (OD value) of the vapor-deposited film was determined as follows. Using a haze meter HM-150 (Murakami Color Research Laboratory), the total light transmittance (Tt) was determined at an entrance opening of φ20 mm and a light beam of φ14 mm. The total light transmittance conforms to JIS K7361. The calculated total light transmittance was substituted into the following equation to calculate the optical density. The measurement results are shown in Table 1.
Optical density (OD value) = -log ₁₀ (total light transmittance/100)

<Transparency>
The haze (H) of the stretched film was measured using a haze meter HM-150 (Murakami Color Research Laboratory) with an inlet opening of φ20 mm and a light beam of φ14 mm. The haze was measured in accordance with JIS K7136. The measurement results are shown in Table 1.

<Surface roughness (Ra)>
The arithmetic mean surface roughness (Ra) of the polyamide resin layer (polyethylene resin layer in Comparative Example 1) in the stretched film was measured in an area of 15 μm × 15 μm using an atomic force microscope (Atomic Force Microscopy, manufactured by Bruker). The measurement results are shown in Table 1.

<Evaluation of curling of stretched film>
The stretched film was cut into a 10 cm square with the curled side facing up. The stretched film was then cut along two diagonals so that 2 cm remained at each of the four corners (see Figure 6). The resulting test piece was used to evaluate curl at four measurement positions. The evaluation criteria were as follows. The evaluation results are shown in Table 1.

(Evaluation criteria)
AA: There's no curl at all.
BB: The tip of the diagonally cut stretched film is slightly warped.
CC: The tip of the diagonally cut stretched film is warped.
DD: Curly.

<Gas barrier property evaluation>
The oxygen permeability (cc/ ^m² ·day·atm) and water vapor permeability (g/ ^m² ·day) of the vapor-deposited films obtained in the Examples, Reference Examples, and Comparative Examples were measured by the following methods. The measurement results are shown in Table 1.

Using an oxygen permeability measuring device (MOCON, OX-TRAN2/20), the vapor-deposited film was set so that the fifth resin layer surface faced the oxygen supply side, and the oxygen permeability was measured in accordance with JIS K7126 at 23°C and a relative humidity of 65%.

Using a water vapor permeability measuring device (MOCON, PERMATRAN-w 3/33), the vapor-deposited film was set so that the fifth resin layer surface faced the water vapor supply side, and the water vapor permeability was measured in accordance with JIS K7129 at 40°C and a relative humidity of 90%.

<Appearance quality characteristics>
A transparent adhesive sheet (LUCIACS CS9862UAS, manufactured by Nitto Denko Corporation) was used. The transparent adhesive sheet had a first main surface and a second main surface. The fifth resin layer surface of the vapor-deposited film was bonded to the first main surface of the transparent adhesive sheet, and the second main surface of the transparent adhesive sheet was bonded to a glass plate (Eagle XG, cut glass, manufactured by Tokyo Tokushu Glass Co., Ltd.). In this way, a test specimen was obtained. Black paper was placed under the glass plate of the test specimen. The stretching direction of the stretched film in the vapor-deposited film and the light source direction of the gloss meter (Rhopoint IQ-S, manufactured by Konica Minolta Inc.) were both set so that they were parallel to each other. The vapor-deposited film was measured for 20° gloss (based on JIS Z8741), reflective haze (based on ASTM E430), image clarity (based on ASTM D5767), and specular reflection peak value (Rspec). The measurement results are shown in Table 1.

1: Vapor-deposited film 2: Laminate 10: Resin substrate 12: Polyolefin resin layer 13: Adhesive resin layer 14: Polyamide resin layer 20: Vapor-deposited film 30: Substrate 40: Adhesive layer 50: Heat seal layer

Claims (13)

A vapor-deposited film used in a laminate for packaging materials, comprising at least a vapor-deposited film and a heat-sealable layer made of polyethylene,
The vapor-deposited film comprises a resin substrate and a vapor-deposited film,
the resin substrate comprises a polyethylene resin layer and a polyamide resin layer,
the vapor-deposited film is provided on the polyamide resin layer,
The polyamide resin layer contains an aliphatic polyamide and an amorphous semi-aromatic polyamide.
Vapor deposition film. The vapor-deposited film according to claim 1 , wherein the content of the aliphatic polyamide in the polyamide resin layer is more than 50% by mass and not more than 99% by mass. 3. The vapor-deposited film according to claim 1, wherein the content of the amorphous semi-aromatic polyamide in the polyamide resin layer is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the aliphatic polyamide. 4. The vapor-deposited film according to claim 1 , wherein the aliphatic polyamide is a crystalline aliphatic polyamide having a melting point of 170°C or higher and 230°C or lower. 5. The vapor-deposited film according to claim 4, wherein the difference (Tm1-Tm2) between the melting point (Tm1) of the crystalline aliphatic polyamide contained in the polyamide resin layer and the melting point (Tm2) of the polyethylene contained in the polyethylene resin layer is 90 °C or less. The vapor-deposited film according to any one of claims 1 to 5 , wherein the resin substrate further comprises an adhesive resin layer between the polyethylene resin layer and the polyamide resin layer. The vapor-deposited film according to any one of claims 1 to 6 , wherein the resin substrate is a co-extruded resin film, and the vapor-deposited film is provided on the polyamide resin layer of the co-extruded resin film. The vapor-deposited film according to any one of claims 1 to 7 , wherein the resin substrate is a stretched film, and the vapor-deposited film is provided on the polyamide resin layer of the stretched film. The vapor-deposited film according to any one of claims 1 to 8 ;
and a heat seal layer composed of polyethylene . The laminate according to claim 9 , further comprising a substrate made of polyethylene on a surface of the vapor-deposited film facing the heat-sealable layer or on a surface opposite to the surface facing the heat-sealable layer. The laminate of claim 10 , further comprising a printed layer on the substrate composed of polyethylene . A packaging material comprising the laminate according to any one of claims 9 to 11 . A packaging container comprising the vapor-deposited film according to any one of claims 1 to 8 or the laminate according to any one of claims 9 to 11 .