WO2024090318A1

WO2024090318A1 - Gas barrier laminate and packaging

Info

Publication number: WO2024090318A1
Application number: PCT/JP2023/037800
Authority: WO
Inventors: 僚神田
Original assignee: Dic株式会社
Priority date: 2022-10-27
Filing date: 2023-10-19
Publication date: 2024-05-02

Abstract

Provided is a gas barrier laminate obtained by laminating: (A) a layer comprising a base material having an inorganic layer formed on at least one surface thereof; (B) a layer provided so as to be in contact with the surface of the base material on which the inorganic layer is formed, the layer (B) containing, with respect to the total solids content, 50 mass% or more of an organic metal compound having a group 4 element as a metallic species; and (C) a layer provided so as to be in contact with the resin layer (B), the layer (C) containing a water-soluble polymer, as well as a metal alkoxide and/or a hydrolysis product thereof. Also provided is packaging obtained using the aforementioned gas barrier laminate. The inorganic layer in the layer (A) is preferably formed through either one of a vapor deposition treatment or a sputtering treatment.

Description

Gas barrier laminate and packaging material

The present invention relates to a gas barrier laminate and a packaging material obtained using the gas barrier laminate.

Packaging materials used for packaging food, daily necessities, medicines, etc. are required to have functions such as strength, resistance to cracking, and gas barrier properties in order to protect the contents from shocks received during distribution, deterioration due to oxygen and moisture, etc. As a laminated film with gas barrier properties, for example, a gas barrier laminated film is known in which a vapor deposition layer made of an inorganic compound such as aluminum oxide is used as the first layer, and a coating agent mainly composed of a water-soluble polymer and an aqueous solution containing at least one of (a) one or more alkoxides and/or their hydrolysates or (b) tin chloride, or a water/alcohol mixed solution, is applied, and a gas barrier coating formed by heating and drying is laminated as the second layer. (See, for example, Patent Document 1). However, since it is difficult to satisfy the required functions with one type of material, a laminate in which different types of polymer materials are bonded together is widely used as a packaging material. In order to provide all the functions of a packaging material for distribution, the gas barrier film disclosed in Patent Document 1 is often used as a packaging material by, for example, laminating a heat-sealable thermoplastic resin layer or a printed layer on the gas barrier coating layer or on the substrate 2, or by laminating multiple resins via adhesive layers. (See Patent Document 1, paragraph 0029.)

In recent years, however, there has been a demand for packaging materials that are not only functional, but also recyclable. There are voices saying that laminated films made of different resins that are made solely with functionality in mind will lower the quality of recycled plastics, and so there are hopes that laminated films made of the same resin type, for example packaging materials made only of olefin-based resins, will be recyclable packaging materials.

As a gas barrier film composed only of an olefin-based resin, for example, a gas barrier film is disclosed which comprises a polyolefin film layer of a first substrate, a polyolefin film layer of a second substrate, and a polyolefin film sealant layer in this order, and the polyolefin film of the first substrate layer or the second substrate layer has an inorganic oxide layer on at least one surface, and exhibits a specific heat shrinkage rate, so that even if the main component is a polyolefin-based film, when it is made into a packaging bag, a laminate capable of high-temperature retort treatment is obtained (see, for example, Patent Document 2). Here, Patent Document 2 describes that it is preferable to provide an anchor coating agent such as a polyester-based polyurethane resin or a polyether-based polyurethane resin between the polyolefin film and the inorganic oxide layer in order to improve the adhesion of the olefin-based resin, which has poor adhesion (see paragraphs 0022 to 0023 of Patent Document 2).
However, this method requires a step of applying an anchor coating agent before providing an inorganic oxide layer on the polyolefin film, and is therefore not suitable for obtaining a recyclable packaging material having gas barrier properties by combining, for example, a general-purpose plastic film such as an olefin film having an inorganic oxide layer.

Japanese Patent No. 2790054 JP 2021-20391 A

The object of the present invention is to provide a gas barrier laminate and packaging material that maintain good adhesion and gas barrier properties even when combined with a plastic film such as an olefin film having a general-purpose inorganic oxide layer, and that is suitable for obtaining a packaging material that is also recyclable.

The inventors have found that the above-mentioned problems can be solved by a gas barrier laminate comprising (A) a general-purpose layer made of a substrate having an inorganic layer formed on at least one surface thereof, (B) a layer containing 50 mass% or more of an organometallic compound having a metal species of a Group 4 element, which is provided so as to be in contact with the surface of the substrate on which the inorganic layer is formed, and (C) a layer containing a water-soluble polymer and a metal alkoxide and/or a hydrolyzate thereof, which is provided so as to be in contact with the resin layer (B).

(A) The layer consisting of a substrate having an inorganic layer formed on at least one surface thereof is not particularly limited, and a commercially available product may be used, or a substrate having an inorganic layer such as a vapor deposition layer formed by a general-purpose method may be used. Even if these substrates are olefin-based resins, (B) the layer used in this application is provided so as to contact the surface of the substrate on which the inorganic layer is formed, and contains 50 mass % or more of an organometallic compound having a metal species of a Group 4 element, thereby providing excellent adhesion to (C) a layer containing a water-soluble polymer and a metal alkoxide and/or a hydrolyzate thereof that exhibits gas barrier properties and is provided thereon.

That is, the present invention is a gas barrier laminate,
(A) a layer made of a substrate having an inorganic layer formed on at least one surface thereof;
(B) a layer provided in contact with the surface of the base material on which the inorganic layer is formed, the layer having an organometallic compound having a Group 4 element as a metal species in an amount of 50 mass% or more based on the total solid content; (C) a layer provided in contact with the resin layer (B), the layer comprising a water-soluble polymer and a metal alkoxide and/or a hydrolysate thereof;
The present invention provides a gas barrier laminate comprising:

The present invention also provides a packaging material using the gas barrier laminate described above.

The present invention makes it possible to provide a gas barrier laminate that maintains good adhesion and gas barrier properties even when combined with a plastic film such as an olefin film having a general-purpose inorganic oxide layer, and is also suitable for producing recyclable packaging materials.

((A) Layer consisting of a substrate having an inorganic layer formed on at least one surface)
The gas barrier laminate of the present invention has (A) a layer made of a substrate having an inorganic layer formed on at least one surface thereof (hereinafter, sometimes referred to as layer (A)).
Here, the substrate used in the (A) layer is not particularly limited in terms of its material, manufacturing method, or shape within the scope in which the effects of the present invention can be obtained, but in most cases, a film shape (sometimes called a sheet, but in the present invention, called a film) is used. Materials for these substrates include, for example, olefin-based resins such as polyethylene (PE), polypropylene (PP), cyclic olefin polymer (COP), and cyclic olefin copolymer (COC), polyester, acrylic, polycarbonate, cellulose ester, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), nylon (NY), and materials containing biomass-derived components. In particular, any film made of a thermoplastic resin mainly composed of an olefin-based resin can be used without any particular limitation. Specific examples of the olefin resin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear (linear) low-density polyethylene, polypropylene (PP), ethylene-propylene copolymers, α-olefin polymers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, cyclic olefin resins, ionomer resins, and polymethylpentene; and modified olefin resins obtained by modifying olefin resins with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids.
Among these, since the effects of the present invention can be significantly obtained, it is preferable to use olefin-based resins such as polyethylene (PE), polypropylene (PP), cyclic olefin polymer (COP), and cyclic olefin copolymer (COC), and polyethylene (PE) and polypropylene (PP) are most preferable.

The substrate used in the (A) layer is not particularly limited, and may be a substrate having a thickness that is generally used for packaging foods, daily necessities, medicines, etc. From the viewpoint of formability and transparency, a film having a thickness in the range of 1 μm to 500 μm is sufficient, preferably 1 μm to 300 μm, and more preferably 1 μm to 100 μm. If the thickness is less than 1 μm, the strength is insufficient, and if it exceeds 500 μm, the rigidity becomes too high, which may make processing difficult.
The method for producing these substrates is not particularly limited, and they can be produced by various film-forming methods such as melt extrusion molding, solution casting molding, and calendar molding, and these may be further subjected to biaxial or uniaxial stretching treatment. Furthermore, films that have been subjected to various surface treatments as necessary may be used.

The (A) layer is a layer having a substrate layer with an inorganic layer formed on at least one side, and the inorganic layer is formed on a part or the entire surface of at least one side of the substrate. The inorganic substances forming these inorganic layers are not particularly limited as long as the effects of the present invention can be obtained, but it is preferable to use one or more selected from metals and metal oxides such as aluminum oxide, silicon oxide, aluminum, zinc oxide, magnesium oxide, calcium oxide, and zirconium oxide, and it is particularly preferable to use one or more selected from aluminum oxide, silicon oxide, aluminum, zinc oxide, and magnesium oxide, as these exhibit good barrier properties.

In the (A) layer of the present invention, the method for forming the inorganic layer is not particularly limited as long as the effects of the present invention can be obtained, but it can be formed by deposition processing, sputtering processing, CVD processing, and coating processing, and it is particularly preferable to use deposition processing and sputtering processing because they can form the inorganic layer uniformly.

((B) A layer having 50% by mass or more of an organometallic compound having a Group 4 element as a metal species, the layer being provided so as to be in contact with the surface of the base material on which the inorganic layer is formed)
The gas barrier laminate of the present invention comprises a layer (B) that is provided so as to be in contact with the surface of the base material on which the inorganic layer is formed and that contains 50 mass % or more of an organometallic compound having a metal species of a Group 4 element (hereinafter, sometimes referred to as layer (B)). Here, layer (B) may be laminated so that at least a part of it is in direct contact with the inorganic layer provided on layer (A).

In the organometallic compound used in the present invention, which contains a Group 4 element as the metal species, specific examples of the Group 4 element metal species include titanium, zirconium, hafnium, and rutherfordium. Among these, titanium or zirconium is preferable.

Organometallic compounds containing these Group 4 elements as metal species include metal alkoxides and/or their oligomers and/or their hydrolysates, metal acylates, metal complexes, coupling agents, etc. These organometallic compounds may be used alone or in combination of two or more.

The metal alkoxide and/or its oligomer and/or its hydrolysate _may be one or more compounds selected from _{metal alkoxides} and their hydrolysates in which the hydroxyl group of the hydroxide of the metal species is substituted with an alkoxyl group represented by _-OC3H7 , _-OC4H9 , _-OCH2CH ( _C2H5 ₎ _C4H9 , -OCH( _CH3 ) ₂ , _-OCnH2n _+1, etc. Examples of the metal alkoxide and its hydrolysate used in the present invention include tetraisopropyl titanate, tetra _- n-butyl titanate, butyl titanate dimer, tetraoctyl titanate, butyl titanate oligomer, tetraisopropyl zirconate, tetra-n-butyl zirconate, etc.
Particularly preferred is one or more metal alkoxides selected from tetra-n-butyl titanate and tetra-n-butyl zirconate and/or hydrolysates thereof.

Specific examples of metal acylates that can be used include titanium isostearate, zirconium isoctylate, and zirconium stearate.

Metal complexes are sometimes called chelating agents. Specific examples include titanium tetraalkylates such as titanium tetrapropylate and titanium tetrabutylate, titanium alkylacetoacetates such as titanium bis(acetylacetate)dipropylate, and zirconium tetraalkylates such as zirconium tetrabutylate.

Coupling agents include titanium coupling agents such as isopropyl triisostearoyl titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, and bis(dioctyl pyrophosphate)ethylene titanate. Zirconium coupling agents include zirconium acetate, ammonium zirconium carbonate, and zirconium fluoride.

In the present invention, the preferred lower limit of the content of the organometallic compound having a Group 4 element as the metal species relative to the total solid content of the (B) layer is 50 mass%, 55 mass%, or 60 mass%. The preferred upper limit of the content is 100% relative to the total solid content.

Layer (B) can be obtained, for example, by a coating method. There are no particular limitations on the coating method, and any known, commonly used coating method can be used. Examples include spraying, spin coating, dip coating, roll coating, blade coating, doctor roll, doctor blade, curtain coating, slit coating, screen printing, inkjet, and dispensing methods.

When layer (B) is obtained by a coating method, a solvent can be used to improve the suitability for coating. The solvent is preferably an organic solvent, and examples of the solvent include alcohol-based organic solvents such as ethanol, n-propanol, isopropyl alcohol, and butanol; ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; aliphatic hydrocarbon-based organic solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon-based organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. One or more of these can be used in combination.

The coating amount of the organometallic compound having a Group 4 element as a metal species is not particularly limited as long as the effects of the present invention can be obtained, but it is preferably coated in an amount of 0.001 to 0.5 g/ ^m2 calculated as solid content, and particularly preferably 0.003 to ^0.2 g/m2 in order to obtain good barrier properties.

It is preferable to provide a drying process for the (B) layer after coating. The drying process may be at room temperature, or may involve forced drying such as heating in an oven, reducing pressure, or blowing air.

As described above, Layer (B) in the present invention contains 50% by mass or more of an organometallic compound having a Group 4 element as the metal species relative to the total solid content, but additives such as stabilizers, resins that serve as binder components, coupling agents, plasticizers, dispersants, surfactants, stabilizers, thickeners, defoamers, wetting agents, hardeners, antiblocking agents, lubricants, preservatives, and inorganic fillers may also be blended within the range in which the effects of the present invention can be obtained.

In particular, when a metal alkoxide and/or an oligomer thereof and/or a hydrolysate thereof is used as the organometallic compound to obtain layer (B) by a coating method, it is preferred that the layer (B) contains a stabilizer.
As the stabilizer, acetylacetone, dehydroacetic acid, benzoylacetone, ethyl acetoacetate, diacetyl and other diketones, carboxylic acids such as acetic acid, hydroxycarboxylic acids such as citric acid, malic acid, tartaric acid, mandelic acid, lactic acid, glycolic acid, hydroxyisobutyric acid, hydroxyacetone, hydroxycarbonyls such as acetoin, cellosolves such as methoxyethanol, dimethoxyethane, glycols such as ethylene glycol, substituted glycol, pentaethylene glycol, hydrazones such as acetolhydrazone, acetoinhydrazone, imines such as diethanolamine, monoketones such as acetone, and the like can be used, and among them, it is preferable to select from acetylacetone, benzoylacetone, citric acid, malic acid, mandelic acid, and acetone.In addition, acetone also functions as a solvent as mentioned above.

In addition, the inclusion of a resin that serves as a binder component can improve suitability for coating. Examples of binder resins include polyvinyl butyral resin, polyvinyl acetal resins such as polyvinyl acetal resin, acrylic resin, polyester resin, styrene resin, styrene-maleic acid resin, maleic acid resin, polyamide resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyvinyl chloride resin, chlorinated polypropylene resin, cellulose-based resin, epoxy resin, alkyd resin, rosin-based resin, rosin-modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, and petroleum resin.

The coupling agent may be any of the known and commonly used ones, such as silane coupling agents, titanium coupling agents, zirconium coupling agents, aluminum coupling agents, etc.

　Any known silane coupling agent may be used, such as epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acryloyl group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane.

Aluminum coupling agents include acetoalkoxyaluminum diisopropylate, aluminum diisopropoxymonoethyl acetoacetate, aluminum trisethyl acetoacetate, aluminum trisacetylacetonate, etc.

Silane compounds include alkoxysilanes, silazanes, siloxanes, etc. Alkoxysilanes include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, 1,6-bis(trimethoxysilyl)hexane, trifluoropropyltrimethoxysilane, etc. Silazanes include hexamethyldisilazane, etc. Siloxanes include hydrolyzable group-containing siloxanes, etc.

((C) A layer comprising a water-soluble polymer and a metal alkoxide and/or a hydrolyzate thereof, provided in contact with the resin layer (B)
The gas barrier laminate of the present invention has a layer (C) that is provided so as to be in contact with the layer (B) and contains a water-soluble polymer and a metal alkoxide and/or a hydrolysate thereof (hereinafter, sometimes referred to as layer (C)). Here, it is sufficient that layer (C) is laminated so that at least a part of layer (C) is in direct contact with layer (B).

The water-soluble polymer used in the gas barrier laminate of the present invention is not particularly limited as long as the effects of the present invention can be obtained, and one or more water-soluble polymers selected from vinyl alcohol polymers such as polyvinyl alcohol, ethylene-vinyl alcohol polymers, vinylpyrrolidone polymers, acrylic acid polymers, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. can be used. Since suitable gas barrier properties can be obtained, it is preferable to use one or more selected from vinyl alcohol polymers, ethylene-vinyl alcohol polymers, vinylpyrrolidone polymers, and acrylic acid polymers.

The metal alkoxide and/or hydrolysate thereof used in the gas barrier laminate of the present invention is not particularly limited as long as the effects of the present invention can be obtained, but metal alkoxides and/or hydrolysates thereof having one or more metal species selected from silicon, aluminum, titanium, and zirconia as the metal species are preferred, and it is more preferred to have one or more metal species selected from silicon and aluminum as the metal species, as this will result in good gas barrier properties.

These metal alkoxides and/or hydrolysates thereof may be one or more _compounds selected from metal alkoxides in which the hydroxyl group of the hydroxide of the above-mentioned metal species is substituted with an alkoxyl group represented by _-OCH3 _, _-OC2H5 , _-OC3H7 , _-OCnH2n _+1, etc., and hydrolysates thereof. Alkoxysilanes such as tetraethoxysilane (TEOS), tetramethoxysilane, tetraproxisilane, tetrabutoxysilane, etc. can be used as the metal alkoxides and/or hydrolysates thereof used in the present invention, and one or more metal alkoxides and/or hydrolysates thereof selected from tetraethoxysilane and tetramethoxysilane are particularly preferred because they provide good gas barrier properties.

In the present invention, it is preferable to prepare a sol by mixing a water-soluble polymer, a metal alkoxide and/or a hydrolysate thereof, water, and one or more organic solvents selected from the group consisting of water-soluble organic solvents such as methanol, ethanol, isopropanol, and 1-propanol, and to coat the obtained sol on layer (B) and dry it to gel and solidify it, thereby forming layer (C) containing a water-soluble polymer and a metal alkoxide and/or a hydrolysate thereof.

In the (C) layer of the present invention, the method for applying the mixed sol is not particularly limited, and any known and commonly used application method can be used. Examples include spraying, spin coating, dip coating, roll coating, blade coating, doctor roll, doctor blade, curtain coating, slit coating, screen printing, inkjet, and dispensing methods. In particular, application by the roll coating method using a gravure coater is preferred because it forms a good coating film.

The amount of the mixed sol to be applied is not particularly limited as long as the effects of the present invention can be obtained, but it is preferable to apply the sol in an amount of 0.1 to 0.5 g/ ^m2 , and it is particularly preferable to apply the sol in an amount of 0.2 to 0.4 g/ ^m2 because this forms a good coating film.

It is preferable to provide a drying process for the (C) layer after coating. The drying process may be room temperature drying, or forced drying such as heating using an oven, reducing pressure, or blowing air.

The (C) layer in the present invention may contain a wetting agent such as a silane coupling agent or a surfactant, as long as the effects of the present invention are achieved.

In the present invention, the (B) layer and the (C) layer may be combined in such a way that they form a strong film through a polycondensation reaction using the sol-gel method. If necessary, various catalysts and solvents may be added, and heating and drying may also be performed.

The method for providing the (C) layer so that it is in contact with the (B) layer is not particularly limited, but may be a general-purpose method, such as a method in which the (B) layer is formed on the (A) layer by coating, and then the (C) layer is continuously formed by coating, or a method in which the (B) layer is formed on the (A) layer by coating, and then wound up, and then unwound, and then the (C) layer is formed on the (B) layer by coating, etc.

(Other layers)
[0043] In the gas barrier laminate of the present invention, in addition to the (A) layer, (B) layer, and (C) layer, various combinations of a resin layer which is a base material used in the (A) layer but has no inorganic layer formed thereon, a layer (second base material) made of a material other than the above, a printed layer, a functional coating layer, an adhesive layer, etc. may be used.

(Second Substrate)
In the present invention, the resin layer which is the base material used in the layer (A) but does not have an inorganic layer formed thereon, as described in the layer (A), may be, for example, an olefin resin such as polyethylene (PE), polypropylene (PP), cyclic olefin polymer (COP), cyclic olefin copolymer (COC), polyester, acrylic, polycarbonate, cellulose ester, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), nylon (NY), or a material containing a biomass-derived component. In particular, any film made of a thermoplastic resin mainly composed of an olefin resin may be used without any particular limitation. Specific examples of the olefin resin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene, polypropylene, ethylene-propylene copolymers, α-olefin polymers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, cyclic olefin resins, ionomer resins, and polymethylpentene; and modified olefin resins obtained by modifying olefin resins with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids. Among these, it is preferable to use olefin resins such as polyethylene (PE), polypropylene (PP), cyclic olefin polymers (COP), and cyclic olefin copolymers (COC), because the effects of the present invention are significantly obtained, and polyethylene (PE) and polypropylene (PP) are the most preferable.

Furthermore, the substrate may be, for example, wood, metal, metal oxide, a resin film other than the resin shown in the layer (A), paper, silicon or modified silicon, or a substrate obtained by bonding different materials. There is no particular restriction on the shape of the substrate, and the substrate may be any shape according to the purpose, such as a flat plate, a sheet, or a three-dimensional shape having a curvature over the entire surface or part thereof. There is also no restriction on the hardness, thickness, etc. of the substrate. Furthermore, when the laminate according to the present invention is used as a packaging material, paper, plastic, metal, metal oxide, etc. may be used as the substrate.

(Printing layer)
From the viewpoint of recycling, it is preferable that the layer structure is as simple as possible, but from the viewpoint of distribution of the packaging material, printing is often required to display the contents of the packaging material or the description or name of the product. Liquid inks such as gravure printing inks and flexographic printing inks are often used as printing inks for this purpose.

The printed layer is a layer on which characters, figures, symbols, and other desired patterns are printed using liquid ink or the like. The laminate may be provided at any position. In this specification, liquid ink is a general term for solvent-based inks used in gravure printing or flexographic printing. It may contain resin, colorant, and solvent as essential components, or it may be a so-called clear ink that contains resin and solvent but does not substantially contain colorant.

The resins used in the liquid ink are not particularly limited, and examples include acrylic resin, polyester resin, styrene resin, styrene-maleic acid resin, maleic acid resin, polyamide resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyvinyl chloride resin, chlorinated polypropylene resin, cellulose-based resin, epoxy resin, alkyd resin, rosin-based resin, rosin-modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, petroleum resin, etc., and one or more of these can be used in combination. Preferably, at least one or two or more selected from polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, and cellulose-based resin are used.

Colorants used in liquid inks include inorganic pigments such as titanium oxide, red iron oxide, antimony red, cadmium red, cadmium yellow, cobalt blue, Prussian blue, ultramarine, carbon black, and graphite; organic pigments such as soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments; and extender pigments such as calcium carbonate, kaolin clay, barium sulfate, aluminum hydroxide, and talc.

The organic solvent used in the liquid ink preferably does not contain aromatic hydrocarbon organic solvents. More specifically, examples of the organic solvents include alcohol organic solvents such as methanol, ethanol, n-propanol, isopropyl alcohol, and butanol; ketone organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; aliphatic hydrocarbon organic solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. These can be used alone or in combination of two or more.

(Functional Coating Layer)
Examples of functional coating layers include coating agents containing various additives. Examples of additives include modifiers, coupling agents, silane compounds, phosphate compounds, organic fillers, inorganic fillers, stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, crystal nucleating agents, oxygen scavengers (compounds having oxygen scavenging function), tackifiers, etc. These various additives may be used alone or in combination of two or more.

　The modifier may be any known or commonly used compound, such as a diol, an amine compound, a carbodiimide, or an isocyanate.

Coupling agents include those that are well known and commonly used, such as silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents.

Titanium coupling agents include, for example, isopropyl triisostearoyl titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, and bis(dioctyl pyrophosphate)ethylene titanate.

Examples of zirconium coupling agents include zirconium acetate, ammonium zirconium carbonate, and zirconium fluoride.

Among the additives, inorganic fillers include inorganic substances such as metals, metal oxides, resins, and minerals, as well as composites of these. Specific examples of inorganic fillers include silica, alumina, titanium, zirconia, copper, iron, silver, mica, talc, aluminum flakes, glass flakes, and clay minerals.

Examples of compounds with oxygen scavenging capabilities include low molecular weight organic compounds that react with oxygen, such as hindered phenol compounds, vitamin C, vitamin E, organic phosphorus compounds, gallic acid, and pyrogallol, as well as transition metal compounds such as cobalt, manganese, nickel, iron, and copper.

Tackifiers include xylene resin, terpene resin, phenol resin, rosin resin, etc. Adding a tackifier can improve adhesion to various substrates immediately after application. The amount of tackifier added is preferably 0.01 to 5 parts by mass per 100 parts by mass of the total resin composition.

(Adhesive Layer)
As the adhesive layer, an adhesive that can be used in a general-purpose lamination method can be used for the purpose of laminating the gas barrier laminate of the present invention, particularly with a second substrate, etc. Examples of the lamination method include dry lamination, wet lamination, non-solvent lamination, and extrusion lamination.
The adhesive used in the dry lamination may be, for example, a one-component or two-component curing or non-curing type vinyl, (meth)acrylic, polyamide, polyester, polyether, polyurethane, epoxy, rubber, or other solvent, water-based, or emulsion type adhesive. A two-component curing adhesive of polyol and isocyanate compound may be used as a two-component curing adhesive. The lamination adhesive may be applied by, for example, a direct gravure roll coating method, a gravure offset roll coating method, a kiss coating method, a reverse roll coating method, a Fountain method, a transfer roll coating method, or other methods.

Various types of adhesives can also be used, with pressure-sensitive adhesives being preferred. Examples of pressure-sensitive adhesives include rubber-based adhesives obtained by dissolving polyisobutylene rubber, butyl rubber, or mixtures of these in organic solvents such as benzene, toluene, xylene, or hexane, or these rubber-based adhesives mixed with tackifiers such as abiethylene acid rosin ester, terpene-phenol copolymer, or terpene-indene copolymer, or acrylic-based adhesives obtained by dissolving acrylic copolymers with a glass transition point of -20°C or less, such as 2-ethylhexyl acrylate-n-butyl acrylate copolymer or 2-ethylhexyl acrylate-ethyl acrylate-methyl methacrylate copolymer, in an organic solvent.

(Types of gas components that can be blocked from permeating)
The gas that the gas barrier laminate of the present invention can block is mainly oxygen, but other examples include inert gases such as carbon dioxide, nitrogen, and argon, alcohol components such as methanol, ethanol, and propanol, phenols such as phenol and cresol, and aroma components made of low molecular weight compounds, for example, the smells of soy sauce, sauce, miso, limonene, menthol, methyl salicylate, coffee, cocoa, etc.

(Packaging materials)
The gas barrier laminate of the present invention can be used as a multi-layer packaging material for protecting foods, medicines, etc. When used as a multi-layer packaging material, the layer structure can be changed depending on the contents, the environment of use, and the form of use. In addition, the package of the present invention may be appropriately provided with an easy-opening treatment or a resealing means.

Contents to be filled into the packaging material of the present invention include, for example, foods such as rice crackers, bean snacks, nuts, biscuits and cookies, wafer snacks, marshmallows, pies, semi-dried cakes, candies, snack foods, and other confectioneries; bread, snack noodles, instant noodles, dried noodles, pasta, aseptically packaged cooked rice, porridge, porridge, packaged rice cakes, and cereal foods, as well as other staple foods; pickles, boiled beans, natto, miso, frozen tofu, tofu, nametake mushrooms, konjac, wild vegetable products, jams, peanut cream, salads, frozen vegetables, and processed potato products, as well as processed livestock products such as ham, bacon, sausages, processed chicken products, and corned beef, These include fish ham and sausages, fish paste products, fishery products such as kamaboko, nori seaweed, tsukudani (food boiled in soy sauce), dried bonito flakes, shiokara (salted fish), smoked salmon, and spicy cod roe; fruit pulp such as peaches, mandarin oranges, pineapples, apples, pears, and cherries; vegetables such as corn, asparagus, mushrooms, onions, carrots, radishes, and potatoes; prepared foods such as frozen and chilled prepared foods, including hamburger steaks, meatballs, seafood fries, gyoza dumplings, and croquettes; dairy products such as butter, margarine, cheese, cream, instant creamy powder, and infant formula; liquid seasonings, retort curry, and pet food.

In addition, it can also be used as a packaging material for a variety of non-food items, including tobacco, disposable hand warmers, medicines such as infusion packs, liquid laundry detergent, liquid kitchen detergent, liquid bath detergent, liquid bath soap, liquid shampoo, liquid conditioner, cosmetics such as lotion and milky lotion, vacuum insulation materials, batteries, etc.

The present invention will be described in more detail below with reference to specific synthesis examples and working examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" respectively represent "parts by mass" and "% by mass" unless otherwise specified.

(Preparation of Layer (A))
An anchor coating solution obtained by mixing an acrylic coating agent (GAC-013S, DIC Corporation) and a polyisocyanate curing agent (KR-90, DIC Corporation) in a mixing ratio of 5:1 was applied onto a biaxially stretched polypropylene film (OPP film FOR, Futamura Chemical Co., Ltd., thickness 20 μm) by a gravure coating method so that the dry film thickness was about 0.05 μm, and dried to obtain an anchor coat layer. Thereafter, in a vacuum deposition apparatus using an electron beam heating method, metallic aluminum was deposited and oxygen gas was introduced, forming an (A) layer having an anchor coat layer on the OPP film and an aluminum oxide deposition layer having a thickness of 20 nm thereon.

(Preparation of Coating Solution (b-1) for (B) Layer)
Tetra-normal butyl titanate (TA-21, Matsumoto Fine Chemical Co., Ltd.) was added to isopropyl alcohol (IPA) and stirred to obtain a coating liquid (b-1). The number of parts is shown in Table 1. At this time, the solid content of tetra-normal butyl titanate relative to the total solid content is 100 mass%.

(Preparation of Coating Solution (c) for (C Layer))
Polyvinyl alcohol (PVA) with a degree of polymerization of 2400 (PVA60-98, Kuraray Co., Ltd., fully saponified PVA) was dissolved in a mixed solvent of water/isopropyl alcohol (IPA) = 98/2 (mass ratio) so that the solid content concentration was 5%, to prepare a PVA solution. Next, 0.1N hydrochloric acid was added to tetraethoxysilane (Si (OC2H5)4, hereinafter referred to as "TEOS"; KBE-04, Shin-Etsu Chemical Co., Ltd.), and the mixture was stirred for 30 minutes to hydrolyze the mixture, to prepare a TEOS hydrolyzed solution with a solid content of 3% (SiO2 equivalent). The PVA solution and the TEOS hydrolyzed solution were mixed so that the solid content mass ratio of PVA/TEOS (SiO2 equivalent) was 30/70, to prepare a coating liquid (c).

(Preparation of Gas Barrier Laminate)
A coating agent (b-1) was applied onto the prepared (A) layer using bar coater #2, and the dilution solvent was evaporated using a dryer set at a temperature of 50° C. to obtain a (B-1) layer. Thereafter, a coating liquid (c) was applied using bar coater #3, and dried for 1 minute in a hot air dryer set at 80° C. to form a (C) layer, which was a gas barrier laminate.

(Preparation of packaging materials)
Dick Dry LX-830 and KW-75 (both from DIC Corporation) were mixed in a mixing ratio of 10/1.5, and ethyl acetate was added so that the non-volatile content was 25% to obtain an adhesive. The adhesive was then applied onto the (C) layer of the prepared gas barrier laminate using a bar coater #8, and the dilution solvent was evaporated using a dryer set at a temperature of 50°C, after which it was laminated with a non-oriented polypropylene film (CPP film, Toyobo Co., Ltd., P1128). Aging was performed for 3 days at 40°C to obtain a packaging material [(A) layer (substrate is OPP film)/(B) layer/(C) layer/adhesive/CPP film].

(Example)
The same procedure as in Example 1 was carried out except that the composition of the coating liquid (b-1) in Example 1 was changed as shown in Tables 1 to 3, to obtain gas barrier laminates and packaging materials of Examples 2 to 22, respectively. The raw materials used in Tables 1 to 3 are as follows.
Butyl titanate dimer (TA-23, Matsumoto Fine Chemical Co., Ltd.)
Normal butyl zirconate (ZA-65, Matsumoto Fine Chemical Co., Ltd.)
Titanium acetylacetonate (TC-100, Matsumoto Fine Chemical Co., Ltd.)
Titanium tetraacetylacetonate (TC-401, Matsumoto Fine Chemical Co., Ltd.)
Zirconium monoacetylacetonate (ZC-540, Matsumoto Fine Chemical Co., Ltd.)
Citric acid (Citric acid, Kanto Chemical Co., Ltd.)
Malic acid (Malic acid, Kanto Chemical Co., Ltd.)
Mandelic acid (Mandelic acid, Kanto Chemical Co., Ltd.)
Acetone (Acetone, Kanto Chemical Co., Ltd.)
Polyvinyl butyral (BL-1, Sekisui Chemical Co., Ltd.)
3-Glycidoxypropyltrimethoxysilane (KBM-403, Shin-Etsu Chemical Co., Ltd.)

(Comparative Example 1)
A gas barrier laminate and a packaging material of Comparative Example 1 were obtained in the same manner as in Example 1, except that the layer (B) of Example 1 was not provided and the layer (C) was formed on the layer (A).

(Comparative Examples 2 to 6)
The same procedure as in Example 1 was carried out except that the composition of the coating liquid (b-1) in Example 1 was changed as shown in Table 4, to obtain gas barrier laminates and packaging materials of Comparative Examples 2 to 6, respectively.

(Evaluation item 1: Adhesion)
A piece of Cellotape (registered trademark) (Nichiban, 12 mm width) was applied onto layer (C) of the prepared gas barrier laminate, and the appearance of the coating film when it was quickly peeled off was visually judged according to the following three stages.
(Evaluation criteria)
A: 70% or more of the printed film remained on the film.
Δ: 30% to less than 70% of the printed film remained on the film.
x: Less than 30% of the printed film remained.

(Evaluation item 2: Laminate strength)
The prepared packaging material was cut into 15 mm widths in a direction parallel to the direction in which the adhesive was applied. Then, the end of the long axis of the packaging material (the end cut into 15 mm width) was peeled between the OPP film and the CPP film. The two peeled layers were fixed to an "Autograph AGS-X" manufactured by Shimadzu Corporation, and peeled by a T-type peeling method with an atmospheric temperature of 25°C and a peeling speed of 300 mm/min to measure the tensile strength. The tensile strength measured here was taken as the laminate strength of the laminate of each Example and Comparative Example. The unit of adhesive strength is N/15 mm.

(Evaluation item 3: Gas barrier properties (oxygen permeability))
The oxygen permeability was measured in accordance with JIS-K7126-2:2006 "Plastic films and sheets - Gas permeability test method - Part 2: Constant pressure method" using an oxygen permeability measuring device OX-TRAN2/21 manufactured by Mocon Co., Ltd., under an atmosphere of temperature 23°C and humidity 0% RH, and an atmosphere of temperature 23°C and humidity 90% RH. RH stands for relative humidity. The unit of oxygen permeability is cc/day·atm· ^m2 .

The results are shown in Tables 5 to 8.

In Examples 1 to 22, gas barrier laminates with good adhesion, laminate strength, and gas barrier properties were produced. On the other hand, in Comparative Example 1, which did not have a (B) layer, and Comparative Examples 2 to 6, which did not use 50 mass% or more of an organometallic compound containing a Group 4 element as the metal species as defined in the present invention as the (B) layer, sufficient adhesion, laminate strength, and gas barrier properties were not obtained. Since each Example and Comparative Example has a common configuration of a CPP film, it is believed that the differences in adhesion, laminate strength, and gas barrier properties confirmed between the Examples and Comparative Examples are due to differences in the configurations of the laminate and packaging material.
From the above results, it was confirmed that the gas barrier laminate and packaging material having the configuration of the present invention have good adhesion, lamination strength, and gas barrier properties.

Claims

A gas barrier laminate comprising:
(A) a layer made of a substrate having an inorganic layer formed on at least one surface thereof;
(B) a layer provided in contact with the surface of the base material on which the inorganic layer is formed, the layer having an organometallic compound having a Group 4 element as a metal species in an amount of 50 mass% or more based on the total solid content;
(C) a layer comprising a water-soluble polymer and a metal alkoxide and/or a hydrolyzate thereof, the layer being provided in contact with the resin layer (B);
A gas barrier laminate comprising:
The gas barrier laminate according to claim 1, wherein the inorganic layer in layer (A) is formed by either a vapor deposition process or a sputtering process.
The gas barrier laminate according to claim 1, wherein the inorganic layer in layer (A) is formed from one or more inorganic substances selected from the group consisting of aluminum oxide, silicon oxide, aluminum, zinc oxide, and magnesium oxide.
The gas barrier laminate according to claim 1, wherein the Group 4 element is titanium or zirconium.
The gas barrier laminate according to claim 1, wherein the water-soluble polymer is one or more water-soluble polymers selected from vinyl alcohol polymers, ethylene-vinyl alcohol polymers, vinylpyrrolidone polymers, and acrylamide polymers.
The gas barrier laminate according to claim 1, wherein the metal alkoxide and/or its hydrolysate is a compound having at least one metal selected from silicon and aluminum.
A packaging material comprising the gas barrier laminate according to any one of claims 1 to 6.
The packaging material according to claim 7, which is obtained by laminating the gas barrier laminate according to any one of claims 1 to 6 and a second substrate with an adhesive.