Laminate, oil-resistant sheet, gas barrier sheet, packaging material, and method for producing laminate

Abstract

Provided are a laminate and the like which have high water vapor barrier properties and oxygen barrier properties, and are designed in consideration of recyclability. The laminate has a substrate, a resin layer (1), and a resin layer (2), the resin layer (1) containing a resin with water vapor barrier properties, and the resin layer (2) containing a vinyl alcohol polymer and a urethane polymer. The content of the vinyl alcohol polymer in the resin layer (2) is 25 mass% or more.

Description

Laminate, oil-resistant sheet, gas barrier sheet, packaging material, and method for manufacturing laminate

[0001] The present invention relates to a laminate, an oil-resistant sheet, a gas barrier sheet, a packaging material, and a method for producing a laminate.

[0002] Packaging materials based on paper or the like have conventionally been used as packaging materials for foods, medical products, electronic components, etc. As such packaging materials, Patent Document 1 describes a barrier laminate having a barrier layer containing hydroxy polyurethane, a swellable layered silicate, and a cationic resin on at least one surface of a paper substrate.

[0003] International Publication No. 2023 / 176794

[0004] It is important for packaging materials to have high water vapor barrier properties and oxygen barrier properties. In addition, from the viewpoint of environmental issues, it is desirable for packaging materials to be easily recyclable.

[0005] The present invention aims to provide a laminate, an oil-resistant sheet, a gas barrier sheet, a packaging material, and a method for producing the laminate, which have high water vapor barrier properties and oxygen barrier properties and are designed with recyclability in mind.

[0006] The above-mentioned problem is solved by the following: [1] A laminate having a substrate, a resin layer (1), and a resin layer (2), wherein the resin layer (1) contains a water vapor barrier resin, the resin layer (2) contains a vinyl alcohol-based polymer and a urethane-based polymer, and the content of the vinyl alcohol-based polymer in the resin layer (2) is 25% by mass or more; [2] The laminate of [1], wherein the resin layer (1) and the resin layer (2) are adjacent to each other; [3] The laminate of [1] or [2], wherein the substrate, the resin layer (2), and the resin layer (1) are arranged in this order; [4] Any of the laminates of [1] to [3], wherein the content of the urethane-based polymer in the resin layer (2) is 75 parts by mass or less relative to 100 parts by mass of the vinyl alcohol-based polymer; [5] Any of the laminates of [1] to [4], further comprising a filling layer, wherein the filling layer is adjacent to the substrate; [6] The laminate of [5], wherein the filling layer contains a vinyl alcohol-based polymer; [7] The laminate of any of [1] to [6], wherein the resin layer (2) contains an ethylene-modified vinyl alcohol polymer as the vinyl alcohol polymer; [8] The laminate of any of [1] to [7], wherein the resin layer (1) is a layer formed by coating; [9] The laminate of any of [1] to [8], wherein the water vapor barrier resin is a water-dispersible polymer;

[10] The laminate of [9], wherein the water-dispersible polymer is at least one selected from the group consisting of an olefin-based polymer and a styrene-based polymer;

[11] The laminate of [9] or

[10] , wherein the resin layer (1) further contains a wax;

[12] The laminate of

[11] , wherein the content of the wax in the resin layer (1) is 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the water-dispersible polymer;

[13] The laminate of

[11] or

[12] , wherein the wax is at least one selected from the group consisting of paraffin wax, microcrystalline wax, and carnauba wax;

[14] The laminate of any one of [1] to [8], wherein the water vapor barrier resin is a polyolefin;

[15] The laminate of any one of [1] to

[14] , wherein the resin layer (1) is the outermost layer;

[16] The laminate of any one of [1] to

[15] , wherein the resin layer (2) contains a layered inorganic material;

[17] The laminate of any one of [1] to

[16] , wherein the resin layer (1) is substantially free of a layered inorganic material;

[18] The laminate of any one of [1] to

[17] , wherein the substrate is paper;

[19] An oil-resistant sheet comprising the laminate of any one of [1] to

[18] ;

[20] A gas barrier sheet comprising the laminate of any one of [1] to

[18] ;

[21] A packaging material comprising the laminate of any one of [1] to

[18] ;

[22] A method for producing a laminate of any one of [9] to

[13] and

[15] to

[18] , comprising the steps of applying a coating liquid containing the vinyl alcohol polymer and the urethane polymer and drying at 60 to 140°C for 1 to 30 minutes to provide a resin layer (2), and applying a coating liquid containing the water-dispersible polymer and drying at 60 to 140°C for 1 to 30 minutes to provide a resin layer (1);

[0007] According to the present invention, it is possible to provide a laminate, an oil-resistant sheet, a gas barrier sheet, a packaging material, and a method for producing the laminate, which have high water vapor barrier properties and oxygen barrier properties and are designed with recyclability in mind.

[0008] <Laminate> A laminate according to one embodiment of the present invention has a substrate, a resin layer (1) and a resin layer (2), the resin layer (1) contains a water vapor barrier resin, the resin layer (2) contains a vinyl alcohol polymer and a urethane polymer, and the content of the vinyl alcohol polymer in the resin layer (2) is 25% by mass or more.

[0009] A laminate according to one embodiment of the present invention has high water vapor barrier properties and oxygen barrier properties, and is designed with recyclability in mind. The reasons for this are as follows. This laminate includes both a resin layer (1) containing a water vapor barrier resin and a resin layer (2) containing a vinyl alcohol-based polymer and a urethane-based polymer. By setting the content of the vinyl alcohol-based polymer in the resin layer (2) within a specific range, it is presumed that high water vapor barrier properties and oxygen barrier properties are achieved through the effects of both resin layers. In particular, it is thought that the barrier properties would be reduced if a layer consisting solely of a vinyl alcohol-based polymer, which typically has excellent barrier properties, contained a urethane-based polymer, which is generally considered to have lower barrier properties than the vinyl alcohol-based polymer, as another resin. However, in a laminate according to one embodiment of the present invention, the barrier properties are enhanced by providing a resin layer (2) containing a urethane-based polymer in addition to the vinyl alcohol-based polymer. This is thought to be due to, for example, the formation of a high barrier state due to interactions between the vinyl alcohol-based polymer and the urethane-based polymer in the resin layer (2). Furthermore, in a preferred embodiment where the resin layer (1) and the resin layer (2) are adjacent to each other, it is believed that the water vapor barrier resin in the resin layer (1) and the urethane-based polymer in the resin layer (2) can interact with each other, thereby further enhancing the barrier properties. This phenomenon is particularly pronounced when the water vapor barrier resin in the resin layer (1) is a water-dispersible polymer. Furthermore, since the resin layer (2) in the laminate contains 25% by mass or more of a vinyl alcohol-based polymer, the resin layer (2) is easily dissolved in liquids such as water during the recycling process of the laminate. In other words, in the laminate, the resin layer (2) is easily removed during recycling, facilitating the recycling of other materials (such as the substrate and the resin layer (1)), and it is believed that the laminate can have excellent recyclability. When the water vapor barrier resin in the resin layer (1) is a water-dispersible polymer, it is easy to reduce the thickness of the resin layer (1), which has a significant impact on recyclability, and thus the recyclability is even better.

[0010] In this specification, "recyclability" means a property that allows easy recycling. However, when recycling, it is not necessary for the entire material (for example, the entire laminate) to be recyclable; it is sufficient if at least a portion of the material can be recycled. Furthermore, "repulpability" means a property that allows the pulp in a paper substrate to be dispersed and reused in paper. In the present invention, "adjacent" means being in direct contact or being directly laminated without any other layer in between.

[0011] Each layer will be described in detail below.

[0012] (Substrate) The substrate may be the outermost layer on one side of the laminate. That is, no other layer may be laminated on one side of the substrate. Other layers may be laminated on both sides of the substrate. The substrate may be printed or the like.

[0013] In this specification, the outermost layer refers to a layer having one exposed surface. The term "outermost layer" does not distinguish between the inner surface and the outer surface of the laminate. That is, the laminate has two outermost layers. For example, when the laminate is formed into a bag shape, both the innermost layer and the outermost layer are outermost layers.

[0014] The material of the substrate is not particularly limited, and substrates made of various materials can be used. Examples of substrates that can be used include resin films such as thermoplastic resin films and thermosetting resin films, fiber aggregates such as paper and fabric, and metal foils. The resin film may be a stretched film or a non-stretched film. Among these, the substrate is preferably a fiber aggregate, and more preferably paper. When the substrate is paper, the processability of the laminate can be improved. Furthermore, when the substrate is paper, the laminate can have excellent repulpability.

[0015] The substrate may be a single layer or a multilayer substrate, in which each layer may be made of a different material, such as a multilayer substrate made of paper laminated with a resin film.

[0016] The base paper can be a general paper whose main component is plant-derived pulp. In this specification, the term "main component" refers to the component with the highest content by mass. The base paper is also referred to as a paper base material. In addition to pulp, the paper base material may contain sizing agents, fillers, paper strength agents, retention aids, pH adjusters, drainage aids, waterproofing agents, softeners, antistatic agents, antifoaming agents, slime control agents, dyes, pigments, etc.

[0017] Examples of paper substrates include kraft paper, bleached kraft paper, fine paper, medium-quality paper, alkaline paper, paperboard, glassine paper, semi-glassine paper, and parchment paper, with kraft paper or bleached kraft paper being preferred.

[0018] The basis weight (mass per unit area) of the paper base material is 20 g / m ２ More than 500g / m ２ Preferably, 30 g / m or less ２ More than 300g / m ２ More preferably, 40 g / m or less ２ More than 200g / m ２ More preferably, 50 g / m or less ２ More than 100g / m ２ Even more preferred are the following:

[0019] The density of the paper base material is 0.5 g / cm ３ 1.2g / cm or more ３ Preferably, 0.6 g / cm or less ３ 1.0g / cm or more ３ The following is more preferred:

[0020] The paper substrate can be produced by a conventionally known method, and commercially available paper substrates can also be used.

[0021] The average thickness of the substrate (paper substrate and other substrate) may be, for example, in the range of 1 μm to 1000 μm, in the range of 3 μm to 400 μm, in the range of 5 μm to 100 μm, or in the range of 7 μm to 50 μm.

[0022] (Resin Layer (1)) The resin layer (1) contains a water vapor barrier resin. The resin layer (1) may be a layer in which the content of the water vapor barrier resin is 50% by mass or more and 100% by mass or less. The resin layer (1) may be a layer (coated layer) formed by coating a coating liquid containing a water vapor barrier resin, or a layer (thermal laminate layer) formed by thermal lamination of a film containing a water vapor barrier resin, but is preferably a coated layer. The resin layer (1) contains a water vapor barrier resin, and is therefore a layer that mainly exhibits water vapor barrier properties.

[0023] In this specification, the term "water vapor barrier resin" refers to a resin that can impart water vapor barrier properties. Water vapor barrier resins are classified into water-dispersible polymers and non-water-dispersible polymers.

[0024] (Water-Dispersible Polymer) The resin layer (1) can exhibit good water vapor barrier properties by containing a water-dispersible polymer, for example. The water-dispersible polymer may be, for example, a polymer having structural units derived from a hydrocarbon-based monomer, or a copolymer having structural units derived from a hydrocarbon-based monomer and other structural units. Examples of hydrocarbon-based monomers include olefins and styrene-based compounds, which will be described later. The proportion of structural units derived from hydrocarbon-based monomers to all structural units in the water-dispersible polymer may be, for example, 40 mol% to 100 mol%, 50 mol% to 99 mol%, or 60 mol% to 95 mol%. In this specification, the term "water-dispersible polymer" refers to a polymer that is dispersible in water. The water-dispersible polymer may be a polymer that is substantially insoluble in water but dispersible in water, or a polymer that does not exhibit phase separation at a concentration of 10 wt% in water at a temperature of 25°C. The solubility of the water-dispersible polymer in water at 20°C may be, for example, 1 g / 100 g or less, 0.1 g / 100 g or less, or 0.01 g / 100 g or less. Examples of the water-dispersible polymer include olefin-based polymers, styrene-based polymers, and polyester-based polymers. The water-dispersible polymer may be the main component of the resin layer (1). One or more types of water-dispersible polymers may be used.

[0025] (Olefin-Based Polymer) The olefin-based polymer is a polymer containing an olefin as a monomer. The olefin-based polymer may be a polyolefin, which is a polymer of one or more olefins, or a copolymer of one or more olefins with one or more other monomers other than olefins.

[0026] Examples of the olefin include α-olefins such as ethylene, propylene, n-butene, and isobutylene.

[0027] Examples of the monomer other than the olefin that constitutes the olefin polymer include an unsaturated carboxylic acid compound, a diene compound, a vinyl ester, a vinyl ether, a vinyl halide, a vinylidene halide, and an allyl compound. An unsaturated carboxylic acid compound or a vinyl ester is preferred, and an unsaturated carboxylic acid compound is more preferred.

[0028] The unsaturated carboxylic acid compound refers to an unsaturated carboxylic acid or a compound in which the hydrogen atom of the carboxy group constituting the unsaturated carboxylic acid is substituted with another atom or another group. That is, the unsaturated carboxylic acid compound includes not only unsaturated carboxylic acid but also unsaturated carboxylic acid esters, unsaturated carboxylic acid salts, etc. The unsaturated carboxylic acid compound is preferably a monomer having a carboxy group or a salt thereof.

[0029] Examples of unsaturated carboxylic acid compounds include unsaturated carboxylic acids such as (meth)acrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, and butenetricarboxylic acid; unsaturated carboxylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, itaconic acid monoethyl ester, and fumaric acid monobutyl ester; and unsaturated carboxylic acid salts such as sodium (meth)acrylate. Note that "(meth)acrylic acid" means acrylic acid and methacrylic acid.

[0030] Examples of vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, etc. Of these, vinyl acetate is preferred.

[0031] The olefin polymer is preferably a polyolefin, an olefin-vinyl ester copolymer, or an olefin-unsaturated carboxylic acid copolymer, and more preferably an olefin-unsaturated carboxylic acid copolymer. The olefin-vinyl ester copolymer refers to a copolymer of one or more olefins and one or more vinyl esters. The olefin-unsaturated carboxylic acid copolymer refers to a copolymer of one or more olefins and one or more unsaturated carboxylic acid compounds.

[0032] Examples of the olefin-vinyl ester copolymer include ethylene-vinyl formate copolymer, ethylene-vinyl acetate copolymer, and ethylene-vinyl propionate copolymer, among which ethylene-vinyl acetate copolymer is preferred. These copolymers may further be copolymerized with other monomers copolymerizable with the olefin and vinyl ester.

[0033] Examples of olefin-unsaturated carboxylic acid copolymers include ethylene-(meth)acrylic acid copolymer, ethylene-methyl(meth)acrylate copolymer, ethylene-ethyl(meth)acrylate copolymer, ethylene-butyl(meth)acrylate copolymer, and ethylene-maleic acid copolymer. The olefin-unsaturated carboxylic acid copolymer is preferably an olefin-unsaturated carboxylic acid copolymer, which is a copolymer of one or more olefins and one or more unsaturated carboxylic acids (e.g., ethylene-(meth)acrylic acid copolymer, ethylene-maleic acid copolymer, etc.). The olefin-unsaturated carboxylic acid copolymer is also preferably a copolymer of ethylene and an unsaturated carboxylic acid compound. A particularly preferred example of the olefin-unsaturated carboxylic acid copolymer is ethylene-(meth)acrylic acid copolymer. These copolymers may further be copolymerized with other monomers copolymerizable with the olefin and the unsaturated carboxylic acid compound.

[0034] (Styrene-based polymer) A styrene-based polymer is a polymer containing a styrene-based compound as a monomer. The styrene-based compound refers to styrene and a compound in which the hydrogen atoms of styrene are substituted with other atoms or other groups. Examples of the styrene-based compound include styrene, α-methylstyrene, vinyltoluene, and chlorostyrene, with styrene being preferred.

[0035] Examples of the styrene polymer include polystyrene, styrene-acrylic copolymers, and styrene-butadiene copolymers.

[0036] A styrene-acrylic copolymer is a copolymer of the above-mentioned styrene compound and an acrylic compound. The acrylic compound refers to (meth)acrylic acid and a compound in which the hydrogen atom of the carboxy group constituting (meth)acrylic acid is substituted with another atom or another group. Examples of the acrylic compound include (meth)acrylic acid, (meth)acrylic acid esters, and (meth)acrylic acid salts. Examples of the (meth)acrylic acid esters include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate and ethyl (meth)acrylate. Examples of the (meth)acrylic acid salts include sodium (meth)acrylate.

[0037] Examples of styrene-acrylic copolymers include styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid ester copolymers, styrene-(meth)acrylate copolymers, etc. The styrene-acrylic copolymers may be further copolymerized with other monomers.

[0038] The styrene-butadiene copolymer is a copolymer of the above-mentioned styrene compound and a butadiene compound. The butadiene compound refers to butadiene and compounds in which the hydrogen atoms of butadiene have been substituted with other atoms or other groups. Examples of the butadiene compound include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, with 1,3-butadiene being preferred.

[0039] The styrene-butadiene copolymer is preferably a styrene-butadiene copolymer, which may be further copolymerized with other monomers.

[0040] As the styrene polymer, a styrene-acrylic copolymer and a styrene-butadiene copolymer are preferred, and a styrene-acrylic copolymer is more preferred.

[0041] (Polyester-based polymer) A polyester-based polymer is a polymer in which one or more types of monomers are polymerized via an ester bond. Examples of the polyester-based polymer include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polyglycolic acid, and aromatic liquid crystal polyester.

[0042] From the viewpoint of water vapor barrier properties, the water-dispersible polymer is preferably at least one selected from the group consisting of olefin-based polymers and styrene-based polymers, and more preferably a styrene-based polymer.

[0043] The lower limit of the content of the water-dispersible polymer in the resin layer (1) is preferably 50% by mass, more preferably 60% by mass, and may be 70%, 80%, 90%, 95%, or 99% by mass. By setting the content of the water-dispersible polymer in the resin layer (1) to be equal to or greater than the lower limit, it is possible to further improve the water vapor barrier properties of the laminate. The content of the water-dispersible polymer in the resin layer (1) may be substantially 100% by mass. On the other hand, the upper limit of this content is preferably 99.9% by mass, more preferably 99% by mass, and may be 98%, 96%, 94%, 90%, or 80% by mass.

[0044] (Non-Water-Dispersible Polymer) Examples of non-water-dispersible polymers include polyolefins. Specific examples of polyolefins include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer (EVA), olefin-unsaturated carboxylic acid copolymer ionomers, ethylene-propylene copolymers, ethylene-acrylic acid ester copolymers, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers, polybutene, polypentene, and other olefin homo- or copolymers, graft-modified versions of these olefin homo- or copolymers with unsaturated carboxylic acids or their esters, and blends thereof. Among these, at least one selected from the group consisting of low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and polypropylene is preferred, with linear low-density polyethylene being more preferred.

[0045] The content of the non-dispersible polymer in the resin layer (1) may be 90% by mass or more, 95% by mass or more, 99% by mass or more, or substantially 100% by mass.

[0046] (Wax) In a preferred embodiment of the present invention, the resin layer (1) contains a wax. When the resin layer (1) contains a wax, the water vapor barrier resin contained in the resin layer (1) is preferably a water-dispersible polymer. The wax may be, for example, an organic substance having an alkyl group that is solid or semi-solid at room temperature (e.g., 20°C) and melts in a temperature range from room temperature to 100°C (i.e., a melting point of 20°C or higher and 100°C or lower). The melting point of the wax may be 40°C or higher and 90°C or lower, or 50°C or higher and 80°C or lower. The wax may be an ester of a fatty acid and an alcohol.

[0047] Examples of waxes include natural waxes such as animal- or plant-derived waxes (e.g., beeswax, carnauba wax, etc.), mineral waxes (e.g., microcrystalline wax, etc.), and petroleum wax; and synthetic waxes such as polyethylene wax, paraffin wax, and polyester wax. The wax is preferably at least one selected from the group consisting of paraffin wax, microcrystalline wax, and carnauba wax. Use of such waxes can further enhance the water vapor barrier properties of the laminate. One or more waxes can be used.

[0048] Commercially available waxes can be used. Commercially available carnauba waxes include "Cellosol 524" manufactured by Chukyo Yushi Co., Ltd. and "ML160RPH" manufactured by Michelman Co., Ltd. Commercially available paraffin waxes include "Hydrin L-700" manufactured by Chukyo Yushi Co., Ltd. and "Paraffin WAX-155" manufactured by Nippon Seiro Co., Ltd. Commercially available dispersions containing a water-dispersible polymer and a wax may also be used to form the resin layer (1). Commercially available dispersions of this type include "XP-8829" manufactured by Seiko PMC Corporation and "Joncryl (registered trademark) 4130" manufactured by BASF SE. In one embodiment, the resin layer (1) may not contain wax. Examples of commercially available dispersions of water-dispersible polymers that do not contain wax include "Joncryl (registered trademark) 4110" manufactured by BASF SE and "Zaixen (registered trademark) AC" manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0049] The lower limit of the wax content in the resin layer (1) is preferably 0.1 parts by mass, and may be 0.5 parts by mass, 1 part by mass, 2 parts by mass, 3 parts by mass, 5 parts by mass, 7 parts by mass, or 10 parts by mass, relative to 100 parts by mass of the water vapor barrier resin (preferably a water-dispersible polymer). By setting the wax content to be equal to or greater than the lower limit, it is possible to further improve the water vapor barrier properties of the laminate. On the other hand, the upper limit of the content is preferably 20 parts by mass, and may be 15 parts by mass, 10 parts by mass, 8 parts by mass, 6 parts by mass, or 5 parts by mass. By setting the wax content to be equal to or less than the upper limit, it is possible to ensure that the laminate fully exhibits water vapor barrier properties while improving the heat sealability when the resin layer (1) is the outermost layer, the adhesion to other layers when other layers are laminated on the surface of the resin layer (1), and the printability when printing is performed on the surface of the resin layer (1).

[0050] (Other Components, etc.) The resin layer (1) may further contain components other than the water vapor barrier polymer and wax. Examples of the other components include resins other than the water vapor barrier polymer, layered inorganic materials, dispersants, surfactants, antifoaming agents, dyes, thickeners, etc.

[0051] In one embodiment, the resin layer (1) may contain a layered inorganic material. As the layered inorganic material, materials described below are preferably used. The upper limit of the content of the layered inorganic material in the resin layer (1) is preferably 10% by mass, more preferably 3% by mass, and even more preferably 1% by mass, and may be 0.5% by mass, 0.1% by mass, or 0.01% by mass. The lower limit of the content of the layered inorganic material in the resin layer (1) may be 0% by mass. In one embodiment, it is preferable that the resin layer (1) does not substantially contain a layered inorganic material. The resin layer (1) may not contain a layered inorganic material. When the content of the layered inorganic material in the resin layer (1) is equal to or less than the upper limit or when the resin layer (1) does not contain a layered inorganic material, a decrease in water vapor barrier property due to cracking of the layered inorganic material in the resin layer (1) when the laminate is folded can be suppressed. Furthermore, when the resin layer (1) is the outermost layer, a decrease in heat sealability due to the presence of the layered inorganic material in the resin layer (1) can be suppressed. When the resin layer (1) contains a layered inorganic material, the water vapor barrier resin contained in the resin layer (1) is preferably a water-dispersible polymer.

[0052] The total content of the water vapor barrier polymer and the wax, which is an optional component, in the resin layer (1) may be 90% by mass or more, 95% by mass or more, 99% by mass or more, or substantially 100% by mass.

[0053] The lower limit of the mass per unit area of ​​one resin layer (1) is 1 g / m ２ is preferred, and 3 g / m ２ More preferably, 5 g / m ２ More preferably, 7 g / m ２ Even more preferably, 10 g / m ２ When the mass per unit area of ​​one resin layer (1) is equal to or greater than the lower limit, the water vapor barrier properties of the laminate can be further improved. Furthermore, when the resin layer (1) is the outermost layer, when the mass per unit area of ​​one resin layer (1) is equal to or greater than the lower limit, the resin layer (1) can function as a sufficiently good sealant layer. The upper limit of the mass per unit area of ​​one resin layer (1) is 100 g / m ２ is preferred, and 40 g / m ２More preferably, 20 g / m ２ More preferably, 15 g / m ２ When the mass per unit area of ​​one resin layer (1) is equal to or less than the upper limit, it is possible to reduce the thickness of the laminate.

[0054] The thickness of the resin layer (1) is preferably 0.1 μm or more and 200 μm or less, and more preferably 1 μm or more and 100 μm or less.

[0055] (Resin layer (2)) The resin layer (2) contains a vinyl alcohol polymer and a urethane polymer. The resin layer (2) may be a layer having a resin content of 50% by mass or more and 100% by mass or less. The resin layer (2) may be a layer formed by coating (coated layer). The resin layer (2) is a layer that mainly exhibits oxygen barrier properties. However, as described above, by containing a urethane polymer in addition to a vinyl alcohol polymer in the resin layer (2), the water vapor barrier properties of the laminate can be greatly improved.

[0056] (Vinyl alcohol polymer) The vinyl alcohol polymer is a polymer having a vinyl alcohol unit (—CH ２ Vinyl alcohol polymers are generally obtained by saponifying vinyl ester polymers. One or more vinyl alcohol polymers can be used.

[0057] The viscosity-average degree of polymerization of the vinyl alcohol-based polymer is preferably 200 or more and 5,000 or less. The lower limit of the viscosity-average degree of polymerization may be 300, 400, 500, or 800. On the other hand, the upper limit of the viscosity-average degree of polymerization may be 3,000, 2,500, 2,000, 1,200, 1,000, 700, or 500. When the viscosity-average degree of polymerization of the vinyl alcohol-based polymer is within the above range, the water vapor barrier property, oxygen barrier property, etc. of the laminate can be improved, and the coatability and strength of the formed layer, etc. can also be optimized.

[0058] The viscosity-average degree of polymerization of a vinyl alcohol polymer is measured in accordance with JIS K 6726:1994. Specifically, the intrinsic viscosity [η] (liters / g) of the vinyl alcohol polymer is measured in water at 30°C, and the viscosity-average degree of polymerization P is calculated using the value of the intrinsic viscosity [η] according to the following formula. When the saponification degree of the vinyl alcohol polymer is less than 99.5 mol%, the polymer is saponified to a saponification degree of 99.5 mol% or more, and then the intrinsic viscosity [η] is measured. P = ([η] x 10 ４ / 8.29) （１／０．６２）

[0059] The lower limit of the saponification degree of the vinyl alcohol polymer is preferably 70 mol%, more preferably 80 mol%, more preferably 90 mol%, even more preferably 95 mol%, and may be 96 mol%, 97 mol%, or 98 mol%. Having a saponification degree equal to or greater than the lower limit can improve the water vapor barrier property, oxygen barrier property, etc. of the laminate. On the other hand, the upper limit of the saponification degree may be 100 mol% or 99.9 mol%. The saponification degree of the vinyl alcohol polymer is measured in accordance with JIS K 6726:1994.

[0060] The vinyl alcohol polymer may have a monomer unit derived from a monomer other than the vinyl alcohol unit and the vinyl ester unit. Examples of such other monomers include α-olefins such as ethylene, propylene, n-butene, and isobutylene; (meth)acrylic acid and its salts; (meth)acrylic acid esters; (meth)acrylamide; (meth)acrylamide derivatives such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, diacetone(meth)acrylamide, (meth)acrylamidopropanesulfonic acid and its salts, (meth)acrylamidopropyldimethylamine and its salts or quaternary salts thereof, and N-methylol(meth)acrylamide and its derivatives; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, and i-propyl vinyl ether. Examples of suitable vinyl ethers include vinyl ethers such as vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; unsaturated dicarboxylic acids and salts or esters thereof such as maleic acid, itaconic acid, and fumaric acid; vinyl silyl compounds such as vinyltrimethoxysilane; isopropenyl acetate; 1,4-diacetoxybutene; 3,4-diacetoxy-1-butene; vinylformamide; and vinylpyrrolidone. In this specification, a vinyl alcohol polymer that is substantially free of other monomer units than vinyl alcohol units and vinyl ester units is also referred to as polyvinyl alcohol.

[0061] As the other monomer, an α-olefin is preferred, and ethylene is more preferred. That is, the vinyl alcohol polymer may be an α-olefin-vinyl alcohol copolymer or an ethylene-vinyl alcohol copolymer. The use of such a vinyl alcohol polymer can further improve the water vapor barrier property of the laminate. In this specification, a vinyl alcohol polymer having a monomer unit derived from an α-olefin (α-olefin unit) is also referred to as an α-olefin-modified vinyl alcohol polymer, and a vinyl alcohol polymer having a monomer unit derived from ethylene (ethylene unit) is also referred to as an ethylene-modified vinyl alcohol polymer. Furthermore, a vinyl alcohol polymer that is substantially free of other monomer units other than vinyl alcohol units, vinyl ester units, and α-olefin units is also referred to as an α-olefin-modified polyvinyl alcohol, and a vinyl alcohol polymer that is substantially free of other monomer units other than vinyl alcohol units, vinyl ester units, and ethylene units is also referred to as an ethylene-modified polyvinyl alcohol.

[0062] The lower limit of the content of α-olefin units relative to all monomer units in the α-olefin-vinyl alcohol copolymer (α-olefin-modified vinyl alcohol polymer or α-olefin-modified polyvinyl alcohol) is preferably 0.1 mol%, more preferably 0.5 mol%, even more preferably 1 mol%, and may be 2 mol%, 3 mol%, 4 mol%, or 5 mol%. On the other hand, the upper limit of this content is preferably 20 mol%, more preferably 15 mol%, even more preferably 13 mol%, and may be 10 mol%, 8 mol%, 6 mol%, or 5 mol%.

[0063] The lower limit of the content of ethylene units relative to all monomer units in an ethylene-vinyl alcohol copolymer (ethylene-modified vinyl alcohol polymer or ethylene-modified polyvinyl alcohol) (hereinafter, sometimes referred to as the ethylene modification amount) is preferably 0.1 mol%, more preferably 0.5 mol%, even more preferably 1 mol%, and may be 2 mol%, 3 mol%, 4 mol%, or 5 mol%. On the other hand, the upper limit of this content is preferably 20 mol%, more preferably 15 mol%, even more preferably 13 mol%, and may be 10 mol%, 8 mol%, 6 mol%, or 5 mol%. In one embodiment, the ethylene modification amount of the ethylene-modified vinyl alcohol polymer or ethylene-modified polyvinyl alcohol is preferably 0.1 mol% or more and 20 mol% or less, more preferably 2 mol% or more and 10 mol% or less, and even more preferably 4 mol% or more and 8 mol% or less.

[0064] The total content of vinyl alcohol units, vinyl ester units, and any α-olefin units relative to all monomer units in the vinyl alcohol polymer is preferably 95 mol% or more, more preferably 99 mol% or more, and may be 100 mol%.

[0065] The lower limit of the content of the vinyl alcohol-based polymer in the resin layer (2) is 25% by mass, preferably 40% by mass, more preferably 50% by mass, even more preferably 60% by mass, even more preferably 70% by mass, and may be 75%, 80%, 85%, 90%, 91%, 92%, 93%, or 94% by mass. On the other hand, the upper limit of the content of the vinyl alcohol-based polymer in the resin layer (2) is preferably 99% by mass, and may be 98% by mass, or may be 96%, 94%, 92%, or 90% by mass. By setting the content of the vinyl alcohol-based polymer in the resin layer (2) within the above range, the water vapor barrier property, oxygen barrier property, etc. of the laminate can be further improved. Furthermore, by setting the content of the vinyl alcohol-based polymer in the resin layer (2) to be equal to or greater than the above lower limit, the solubility of the resin layer (2) in water, etc. is increased, and the recyclability of the laminate is improved.

[0066] The resin layer (2) preferably contains an ethylene-modified vinyl alcohol polymer as the vinyl alcohol polymer. When the resin layer (2) contains an ethylene-modified vinyl alcohol polymer, the lower limit of the content of the ethylene-modified vinyl alcohol polymer in the resin layer (2) is preferably 25% by mass, more preferably 40% by mass, even more preferably 50% by mass, even more preferably 60% by mass, and may be 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, or 94% by mass. On the other hand, the upper limit of the content of the ethylene-modified vinyl alcohol polymer in the resin layer (2) is preferably 99% by mass, and may be 98%, 96%, 94%, 92%, or 90% by mass.

[0067] (Urethane-based polymer) The urethane-based polymer is a polymer having a urethane bond. The urethane-based polymer may be polyurethane. The urethane-based polymer is typically a polymer obtained by reacting a polyisocyanate with a polyol. The urethane-based polymer preferably contains at least one of a metaxylylene diisocyanate-derived monomer unit and a hydrogenated metaxylylene diisocyanate-derived monomer unit. In the urethane-based polymer, the total content of the metaxylylene diisocyanate-derived monomer unit and the hydrogenated metaxylylene diisocyanate-derived monomer unit relative to the total amount of the polyisocyanate-derived monomer units is preferably 50 mol% or more. Such a urethane-based polymer exhibits high cohesive strength due to hydrogen bonds and the stacking effect between xylylene groups, and therefore has excellent oxygen barrier properties. The content is １ The identification can be performed using known analytical techniques such as H-NMR.

[0068] The urethane polymer can be synthesized by a known method. For example, the urethane polymer described in WO 2015 / 016069 can be used.

[0069] The urethane polymer may be a commercially available product, such as "Takelac (registered trademark) W," "Takelac (registered trademark) WPB," or "Takelac (registered trademark) WS" manufactured by Mitsui Chemicals, Inc., or "NeoRez (registered trademark) R670XP" manufactured by Covestro AG, and more specifically, "NeoRez (registered trademark) R670XP" can be used.

[0070] The upper limit of the content of the urethane polymer in the resin layer (2) is preferably 75 parts by mass, more preferably 50 parts by mass, even more preferably 30 parts by mass, even more preferably 20 parts by mass, and particularly preferably 15 parts by mass, per 100 parts by mass of the vinyl alcohol polymer. The upper limit of the content of the urethane polymer in the resin layer (2) may be 12 parts by mass, 10 parts by mass, or 8 parts by mass per 100 parts by mass of the vinyl alcohol polymer. The lower limit of the content of the urethane polymer in the resin layer (2) is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 3 parts by mass, per 100 parts by mass of the vinyl alcohol polymer. In one embodiment, the content of the urethane polymer in the resin layer (2) is preferably 0.5 parts by mass or more and 75 parts by mass or less, more preferably 0.5 parts by mass or more and 50 parts by mass or less, and even more preferably 0.5 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of the vinyl alcohol polymer. When the content of the urethane polymer is within the above range, the water vapor barrier property and oxygen barrier property can be further improved.

[0071] The lower limit of the total content of the vinyl alcohol polymer and the urethane polymer in the resin layer (2) is preferably 50% by mass, more preferably 60% by mass, even more preferably 70% by mass, and may be 80%, 90%, 95%, or 99% by mass. The upper limit of the total content of the vinyl alcohol polymer and the urethane polymer in the resin layer (2) may be 100%, 99%, 90%, or 80% by mass. When the total content of the vinyl alcohol polymer and the urethane polymer in the resin layer (2) is within the above range, the water vapor barrier property and oxygen barrier property of the laminate tend to be further improved. Furthermore, the ratio of the total of the vinyl alcohol polymer and the urethane polymer to the resin components in the resin layer (2) is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more. When the ratio of the total of the vinyl alcohol polymer and the urethane polymer to the resin components in the resin layer (2) is equal to or greater than the above lower limit, the water vapor barrier property and oxygen barrier property of the laminate tend to be further improved.

[0072] (Other Components, etc.) The resin layer (2) may further contain components other than the vinyl alcohol polymer and the urethane polymer. Examples of the other components include resins other than the vinyl alcohol polymer and the urethane polymer, layered inorganic materials, dispersants, surfactants, antifoaming agents, dyes, preservatives, fillers, interlayer adhesives, thickeners, etc.

[0073] The resin layer (2) preferably further contains a layered inorganic material, which can further enhance the oxygen barrier properties of the laminate.

[0074] According to the findings of the present inventors, a laminate having good water vapor barrier properties and gas barrier properties can be obtained even when a layer containing polyethyleneimine or the like is provided as the resin layer (2) instead of a urethane-based polymer. However, even if a layered inorganic material is added to the resin layer (2) in order to further enhance the oxygen barrier properties of such a laminate, forming such a resin layer (2) becomes difficult. That is, when a coating liquid containing a vinyl alcohol-based polymer, polyethyleneimine, and a layered inorganic material and using water as a solvent or dispersion medium is prepared, gelation of the coating liquid occurs, making coating difficult. In contrast, a coating liquid containing a vinyl alcohol-based polymer, a urethane-based polymer, and a layered inorganic material and using water as a solvent or dispersion medium is less likely to gel and is easy to coat. Therefore, a resin layer (2) containing a vinyl alcohol-based polymer, a urethane-based polymer, and a layered inorganic material has the advantages of high barrier properties and ease of formation.

[0075] The content of the layered inorganic material in the resin layer (2) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of the vinyl alcohol-based polymer. The content is preferably less than 50 parts by mass, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less. By setting the content of the layered inorganic material in the resin layer (2) within the above range, it is possible to further improve the oxygen barrier property, etc. From the viewpoint of coatability, 30 parts by mass or less, 25 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less may be preferred.

[0076] Examples of layered inorganic materials include micas, mica, talc, montmorillonite, kaolinite, vermiculite, smectite, hectorite, taeniolite, and acid clay, with mica being preferred. The layered inorganic materials may be natural or synthetic. One or more types of layered inorganic materials may be used.

[0077] The average particle size of the layered inorganic material is preferably from 1 μm to 50 μm, more preferably from 4 μm to 30 μm. The average particle size is the average value of the particle sizes (longest diameter) of 20 randomly selected particles in a magnified image obtained by atomic force microscopy.

[0078] The aspect ratio of the layered inorganic material can be, for example, 20 or more, 100 or more, or 300 or more, but is preferably 500 or more, more preferably 700 or more, and even more preferably 900 or more. The aspect ratio may be, for example, 10,000 or less, 7,000 or less, 3,000 or less, or 2,000 or less. The aspect ratio refers to the average major diameter relative to the average thickness of flat particles. The average thickness and average major diameter are the average values ​​of the thickness and major diameter (longest diameter) of any 20 particles in an enlarged image obtained by atomic force microscopy.

[0079] The lower limit of the total content of the vinyl alcohol polymer, the urethane polymer, and the optional layered inorganic material in the resin layer (2) is preferably 80% by mass, more preferably 90% by mass, and even more preferably 95% by mass, and may be 97%, 98%, 99%, or 99.9% by mass. The upper limit of the total content of the vinyl alcohol polymer, the urethane polymer, and the optional layered inorganic material in the resin layer (2) may be 100%, 99%, 90%, or 80% by mass.

[0080] The lower limit of the mass per unit area of ​​one resin layer (2) is 0.3 g / m ２ is preferred, and 0.5 g / m ２ More preferably, 1 g / m ２ More preferably, 1.5 g / m ２ or 2 g / m ２ When the mass per unit area of ​​one resin layer (2) is equal to or greater than the lower limit, the water vapor barrier property, oxygen barrier property, etc. can be improved. The upper limit of the mass per unit area of ​​one resin layer (2) is 15 g / m ２ is preferred, and 10 g / m ２ More preferably, 6 g / m ２ More preferably, 4 g / m ２When the mass per unit area of ​​one resin layer (2) is equal to or less than the upper limit, the thickness of the laminate can be reduced.

[0081] (Other Layers) The laminate according to one embodiment of the present invention may further include layers other than the substrate, the resin layer (1), and the resin layer (2). Examples of the other layers include other resin layers, vapor-deposited layers, and metal foil layers.

[0082] The laminate according to one embodiment of the present invention preferably has a filler layer as another layer. Usually, the filler layer is a layer that is directly laminated on the substrate. The filler layer may be a layer adjacent to the substrate. The filler layer may be a layer formed by coating (a coating layer), or may be a layer containing a resin as a main component. The filler layer may be called an undercoat layer, a precoat layer, or the like.

[0083] Examples of resins used in the filling layer include olefin polymers, styrene polymers, polyester polymers, urethane polymers, and vinyl alcohol polymers. Examples of the olefin polymers, styrene polymers, and polyester polymers include those exemplified as the water-dispersible polymers contained in the resin layer (1). Examples of the vinyl alcohol polymers include those exemplified as the vinyl alcohol polymers contained in the resin layer (2). In the filling layer, a cationic resin can also be used in combination with such a resin.

[0084] Among these, vinyl alcohol polymers are preferred as the resin used in the filling layer. By using a vinyl alcohol polymer in the filling layer, good filling properties can be exhibited and the recyclability of the laminate can also be improved. The preferred form of the vinyl alcohol polymer as the resin used in the filling layer is the same as the preferred form of the vinyl alcohol polymer contained in the resin layer (2). For example, the vinyl alcohol polymer used in the filling layer is preferably an α-olefin-vinyl alcohol copolymer (α-olefin-modified polyvinyl alcohol), and more preferably an ethylene-vinyl alcohol copolymer (ethylene-modified polyvinyl alcohol).

[0085] When the filling layer contains a vinyl alcohol-based polymer, the filling layer may or may not further contain a urethane-based polymer, as in the resin layer (2). In one embodiment, it is preferable that the filling layer does not substantially contain a urethane-based polymer. When the filling layer contains a vinyl alcohol-based polymer, the content of the urethane-based polymer in the filling layer relative to 100 parts by mass of the vinyl alcohol-based polymer in the filling layer may be, for example, less than 1 part by mass, less than 0.5 parts by mass, or less than 0.1 parts by mass.

[0086] The lower limit of the resin content in the filling layer is preferably 50% by mass, more preferably 60% by mass, and may be 70%, 80%, or 90% by mass, while the upper limit of this content may be 100%, 99%, 95%, 90%, or 80% by mass.

[0087] The lower limit of the content of the vinyl alcohol polymer in the filling layer is preferably 50% by mass, more preferably 60% by mass, and may be 70%, 80%, or 90% by mass, while the upper limit of this content may be 100%, 99%, 95%, 90%, or 80% by mass.

[0088] The filling layer may further contain a layered inorganic material. On the other hand, the filling layer may not contain a layered inorganic material. The upper limit of the content of the layered inorganic material in the filling layer can be, for example, 40 mass%, and may be 30 mass%, 20 mass%, 10 mass%, 3 mass%, 1 mass%, 0.5 mass%, 0.1 mass%, or 0.01 mass%. The lower limit of the content of the layered inorganic material in the filling layer may be 0 mass% or 1 mass%.

[0089] The filling layer may further contain components other than the resin and the layered inorganic material, such as a dispersant, a surfactant, an antifoaming agent, a dye, and a thickener.

[0090] The lower limit of the mass per unit area of ​​one filling layer is 0.1 g / m ２is preferred, and 0.3 g / m ２ More preferably, 0.5 g / m ２ When the mass per unit area of ​​one filling layer is equal to or greater than the lower limit, the water vapor barrier property and the like can be further improved. The upper limit of the mass per unit area of ​​one filling layer is 10 g / m ２ is preferred, and 5 g / m ２ More preferably, 2 g / m ２ When the mass per unit area of ​​one filling layer is equal to or less than the upper limit, it is possible to reduce the thickness of the laminate.

[0091] The laminate according to one embodiment of the present invention may have a sealant layer other than the resin layer (1). When the resin layer (1) is the outermost layer, the resin layer (1) may function as a sealant layer. The sealant layer may be referred to as a heat seal layer or the like. The sealant layer is usually the outermost layer of the laminate. The outermost layer on one side of the laminate may be a sealant layer, or the outermost layers on both sides may both be sealant layers. The sealant layer may be a layer formed by coating (coating layer).

[0092] The sealant layer is usually composed mainly of a polymer. The polymer used in the sealant layer may be at least one selected from the group consisting of olefin-based polymers and styrene-based polymers. The sealant layer may further contain other components in addition to the polymer. Examples of other components include dispersants, surfactants, antifoaming agents, dyes, and thickeners.

[0093] When the laminate according to one embodiment of the present invention has a vapor-deposited layer, it can exhibit excellent water vapor barrier properties, oxygen barrier properties, etc. The vapor-deposited layer is a layer formed by vapor deposition, and is preferably a layer formed by vapor deposition of an inorganic substance (inorganic vapor-deposited layer).

[0094] Examples of materials constituting the vapor-deposited layer include inorganic materials such as metals (e.g., aluminum), metal oxides (e.g., silicon oxide, aluminum oxide, magnesium oxide), metal nitrides (e.g., silicon nitride), metal nitride oxides (e.g., silicon oxynitride), and metal carbonitrides (e.g., silicon carbonitride). Among the examples of inorganic materials listed above, silicon is considered to be included in the metals. The vapor-deposited layer may be composed of an organic material, or may be composed of both an organic material and an inorganic material. From the viewpoints of barrier properties, industrial productivity, and the like, the material constituting the vapor-deposited layer is preferably aluminum, aluminum oxide, silicon oxide, magnesium oxide, or silicon nitride, more preferably aluminum or aluminum oxide, and even more preferably aluminum.

[0095] The lower limit of the average thickness of one vapor-deposited layer is preferably 5 nm, more preferably 10 nm, even more preferably 20 nm, and even more preferably 30 nm. By setting the average thickness of the vapor-deposited layer to the above lower limit or more, it is possible to improve the barrier properties, etc. On the other hand, the upper limit of the average thickness of one vapor-deposited layer is preferably 200 nm, more preferably 150 nm, even more preferably 100 nm, and may be 80 nm or 60 nm. By setting the average thickness of the vapor-deposited layer to the above upper limit or less, cracking of the vapor-deposited layer during bending, etc., can be suppressed, and deterioration of the water vapor barrier properties and oxygen barrier properties after bending can be reduced. The average thickness of the vapor-deposited layer is the average value of the thicknesses at any 10 points on the cross section of the vapor-deposited layer measured using an electron microscope.

[0096] In one embodiment of the present invention, the laminate may not have any layers other than the substrate, the resin layer (1), the resin layer (2), and any filler layer. For example, the laminate may not have a vapor-deposited layer. Furthermore, the laminate may use a substrate provided with a filler layer as the substrate. Examples of such substrates include coated paper.

[0097] (Layer structure, etc.) In a laminate according to one embodiment of the present invention, the resin layer (1) and the resin layer (2) are preferably adjacent to each other. By having the resin layer (1) and the resin layer (2) adjacent to each other, the water vapor barrier resin contained in the resin layer (1) interacts with the vinyl alcohol polymer and the urethane polymer contained in the resin layer (2), resulting in a laminate that is particularly excellent in water vapor barrier property and oxygen barrier property.

[0098] In the laminate according to one embodiment of the present invention, the resin layer (1) is preferably the outermost layer. When the resin layer (1) is the outermost layer, the water vapor barrier resin in the resin layer (1) can be sufficiently present on the outermost surface of the laminate, thereby exhibiting particularly excellent water vapor barrier properties. Furthermore, when the resin layer (1) is the outermost layer, this resin layer (1) can function as a sealant layer.

[0099] In the laminate according to one embodiment of the present invention, the substrate may be paper, and this substrate may be the outermost layer. In such a case, the paper substrate is particularly likely to be dispersed into a pulp state by a liquid such as water during recycling, and has higher repulpability.

[0100] The laminate preferably has a substrate, a resin layer (2), and a resin layer (1) in this order. In this case, another layer may or may not be interposed between the substrate and the resin layer (2). Also, another layer may or may not be interposed between the resin layer (2) and the resin layer (1). In the laminate, it is more preferable that the substrate, the resin layer (2), and the resin layer (1) are directly laminated in this order, or that the substrate, the sealing layer, the resin layer (2), and the resin layer (1) are directly laminated in this order. In this way, in the case of a layer structure in which the resin layer (2) is located between the substrate and the resin layer (1), when the laminate is recycled, the resin layer (2) dissolves in a liquid such as water, which enables easy separation of the substrate and the resin layer (1), thereby improving recyclability.

[0101] In a laminate according to one embodiment of the present invention, the substrate, the resin layer (1), and the resin layer (2) may each be only one layer or two or more layers. In a laminate according to one embodiment of the present invention, the substrate, the resin layer (1), and the resin layer (2) are each preferably only one layer. When there are two or more layers of the substrate, the resin layer (1), and the resin layer (2), their compositions, thicknesses, etc. may be the same or different. Furthermore, when there are two or more layers of either the resin layer (1) or the resin layer (2), there may be a resin layer (1) or a resin layer (2) that is not adjacent to the other of the resin layer (1) and the resin layer (2). It is preferable that at least one pair of the resin layer (1) and the resin layer (2) exists adjacent to each other.

[0102] Examples of the layer structure of the laminate according to one embodiment of the present invention are as follows: 1 represents the resin layer (1), 2 represents the resin layer (2), A represents the filling layer, B represents the sealant layer, and X represents another layer (e.g., a vapor-deposited layer or a metal foil). Substrate / 1 / 2 Substrate / 2 / 1 Substrate / A / 1 / 2 Substrate / A / 2 / 1 Substrate / A / 1 / 2 / B 2 / 1 / Substrate / 1 / 2 1 / 2 / Substrate / 2 / 1 1 / 2 / A / Substrate / A / 2 / 1 B / Substrate / 2 / 1 B / Substrate / A / 2 / 1 B / A / Substrate / A / 2 / 1 Substrate / 1 / 2 / X Substrate / 2 / X / 1 Substrate / A / 1 / 2 / X / B

[0103] The laminate according to one embodiment of the present invention can be suitably used as an oil-resistant sheet, a gas barrier sheet, a flavor barrier sheet, a packaging material, etc. When the outermost layer of the laminate is the resin layer (1) or another sealant layer, the laminate can be used in a state where it is formed into a predetermined shape (for example, a bag shape) by heat-sealing the outermost layers together. The heat-sealing method is not particularly limited, and known methods can be used, such as a hot plate heat sealer, an impulse sealer, an ultrasonic sealer, a frictional heat sealer, a dielectric heating sealer, etc.

[0104] <Method for manufacturing laminate> The method for manufacturing a laminate according to one embodiment of the present invention is not particularly limited, but it can typically be manufactured by providing a resin layer (1) and a resin layer (2) on a substrate by coating. The order of coating for providing the resin layer (1) and the resin layer (2) is not particularly limited, but it is preferable to provide the resin layer (2) and the resin layer (1) on the substrate in this order by coating. In the case of a laminate having a filling layer, the filling layer can also be provided by coating. For example, it is preferable to provide the filling layer, the resin layer (2), and the resin layer (1) on the substrate in this order by coating.

[0105] For example, resin layer (1), resin layer (2), etc. can be provided by applying a coating liquid for forming each layer and drying it. Drying does not need to be performed after each coating liquid, and a simultaneous multi-layer coating method may be employed. Each coating liquid can be applied by a conventionally known method. Coating can be performed using, for example, a blade coater, flexo coater, comma coater, metering rod size press, two-roll size press, shim sizer, bar coater, air knife coater, slit die coater, gravure coater, reverse gravure coater, microgravure coater, gate roll coater, curtain coater, etc.

[0106] The method for drying the applied coating liquid is not particularly limited, and can be carried out using, for example, a hot air dryer, an infrared dryer, a gas burner, a hot plate, or the like.

[0107] The temperature for drying the applied coating liquid is not particularly limited, but in the case of coating both the resin layer (1) and the resin layer (2), it is preferably 60 to 140°C, more preferably 70 to 130°C, and even more preferably 80 to 120°C. The time for drying the applied coating liquid is not particularly limited, but in the case of coating both the resin layer (1) and the resin layer (2), it is preferably 1 to 30 minutes, more preferably 2 to 20 minutes, and even more preferably 3 to 10 minutes. The drying temperature and drying time when coating the resin layer (1) and when coating the resin layer (2) may be the same or different.

[0108] The solvent or dispersion medium for the coating liquid for forming each layer is not particularly limited, and water or an organic solvent (ethanol, isopropyl alcohol, methyl ethyl ketone, toluene, etc.) can be used, with water being preferred.

[0109] A preferred embodiment of the method for producing a laminate according to one embodiment of the present invention is a production method comprising the steps of applying a coating liquid containing the vinyl alcohol polymer and the urethane polymer and drying the coating liquid at 60 to 140°C for 1 to 30 minutes to provide a resin layer (2), and applying a coating liquid containing the water-dispersible polymer and drying the coating liquid at 60 to 140°C for 1 to 30 minutes to provide a resin layer (1). This production method may also comprise the steps of applying a coating liquid containing the vinyl alcohol polymer and the urethane polymer onto a substrate directly or via another layer (for example, a filling layer) and drying the coating liquid at 60 to 140°C for 1 to 30 minutes to provide a resin layer (2), and applying a coating liquid containing the water-dispersible polymer directly onto the resin layer (2) and drying the coating liquid at 60 to 140°C for 1 to 30 minutes to provide a resin layer (1). These manufacturing methods have good productivity, and can sufficiently reduce the amount of the remaining solvent or dispersion medium derived from the coating liquid contained in the resin layer (1) and the resin layer (2), thereby producing a laminate with superior oxygen barrier property and water vapor barrier property.

[0110] In the laminate according to one embodiment of the present invention, the resin layer (1) may be bonded by thermal lamination. Specifically, the laminate can be produced by coating a base material with an optional filling layer, then coating the resin layer (2), and thermally laminating a film containing a water vapor barrier resin onto the resin layer (2). This production method is suitable when the water vapor barrier resin contained in the resin layer (2) is a non-water-dispersible polymer.

[0111] <Oil-resistant sheet> An oil-resistant sheet including a laminate according to one embodiment of the present invention is also a suitable embodiment of the present invention. The oil-resistant sheet according to one embodiment of the present invention includes a laminate according to one embodiment of the present invention, and the oil-resistant sheet may consist solely of a laminate according to one embodiment of the present invention. The oil-resistant sheet may be oil-resistant paper using paper as the substrate.

[0112] The oil-resistant sheet has excellent water vapor barrier properties and oxygen barrier properties and can be highly recyclable. The oil-resistant sheet is suitable for use as packaging for oily foods such as French fries and fried chicken, packaging for wrapping butter, and cooking paper for baking bread and cakes.

[0113] The oil resistance (KIT value) of the oil-resistant sheet is preferably at least grade 5, and more preferably at least grade 6 or at least grade 7. This oil resistance is a value measured on the surface by a kit test based on TAPPI No. T559cm-02.

[0114] <Gas barrier sheet> A gas barrier sheet comprising a laminate according to one embodiment of the present invention is also a suitable embodiment of the present invention. The gas barrier sheet according to one embodiment of the present invention comprises a laminate according to one embodiment of the present invention, and the gas barrier sheet may consist solely of the laminate according to one embodiment of the present invention. The gas barrier sheet may be gas barrier paper in which paper is used as the substrate.

[0115] The gas barrier sheet has excellent water vapor barrier properties and oxygen barrier properties, and can be highly recyclable. The gas barrier sheet is suitable for use as packaging for food, agricultural chemicals, pharmaceuticals, cosmetics, medical products, electronic components, clothing, and the like.

[0116] The oxygen permeability of the gas barrier sheet is 100 cc / atm / m ２ / day or less is preferable, and 30cc / atm / m ２ / day or less is more preferable, and 10cc / atm / m ２ / day or less is more preferable, and 3 cc / atm / m ２ The oxygen permeability is a value measured under conditions of 20°C and 65% RH.

[0117] <Packaging Material> A packaging material including the laminate according to one embodiment of the present invention is also a suitable embodiment of the present invention. The packaging material according to one embodiment of the present invention may include the laminate according to one embodiment of the present invention, the oil-resistant sheet according to one embodiment of the present invention, or the gas barrier sheet according to one embodiment of the present invention.

[0118] The packaging material has excellent water vapor barrier properties and oxygen barrier properties and can be highly recyclable. The packaging material is suitable for use as packaging for, for example, food, agricultural chemicals, pharmaceuticals, cosmetics, medical supplies, electronic components, clothing, and the like.

[0119] For example, a preferred embodiment of the present invention is a laminate having a substrate, a resin layer (1) and a resin layer (2), in which the resin layer (1) contains a water vapor barrier polymer, the resin layer (2) contains a vinyl alcohol-based polymer and a urethane-based polymer, the content of the vinyl alcohol-based polymer in the resin layer (2) is 25% by mass or more (preferably 40% by mass or more, 60% by mass or more, 80% by mass or more, or 90% by mass or more), the resin layer (1) and the resin layer (2) are adjacent to each other, and the laminate has the substrate, the resin layer (2) and the resin layer (1) in this order.

[0120] Furthermore, for example, a preferred embodiment of the present invention is a laminate having a substrate, a resin layer (1) and a resin layer (2), wherein the resin layer (1) contains a water vapor barrier polymer, the resin layer (2) contains a vinyl alcohol-based polymer and a urethane-based polymer, the content of the vinyl alcohol-based polymer in the resin layer (2) is 25% by mass or more (preferably 40% by mass or more, 60% by mass or more, 80% by mass or more, or 90% by mass or more), the resin layer (1) and the resin layer (2) are adjacent to each other, and further comprising a filling layer, wherein the laminate has a substrate, a filling layer, the resin layer (2) and the resin layer (1) in this order, the filling layer is adjacent to the substrate, and the filling layer contains a vinyl alcohol-based polymer.

[0121] Furthermore, for example, one preferred embodiment of the present invention is a laminate having a substrate, a resin layer (1) and a resin layer (2), wherein the resin layer (1) contains a water-dispersible polymer, the resin layer (2) contains a vinyl alcohol-based polymer and a urethane-based polymer, the content of the vinyl alcohol-based polymer in the resin layer (2) is 25% by mass or more (preferably 40% by mass or more, 60% by mass or more, 80% by mass or more, or 90% by mass or more), the resin layer (1) and the resin layer (2) are adjacent to each other, and the substrate, the resin layer (2) and the resin layer (1) are arranged in this order, and the resin layer (2) contains a layered inorganic material.

[0122] Furthermore, for example, one preferred embodiment of the present invention is a laminate having a substrate, a resin layer (1) and a resin layer (2), wherein the resin layer (1) contains a water-dispersible polymer, the resin layer (2) contains a vinyl alcohol-based polymer and a urethane-based polymer, the content of the vinyl alcohol-based polymer in the resin layer (2) is 25% by mass or more (preferably 40% by mass or more, 60% by mass or more, 80% by mass or more, or 90% by mass or more), the resin layer (1) and the resin layer (2) are adjacent to each other, and further comprising a filling layer, the laminate having a substrate, the filling layer, the resin layer (2) and the resin layer (1) in this order, the filling layer is adjacent to the substrate, the filling layer contains a vinyl alcohol-based polymer, the resin layer (2) contains a layered inorganic material, the resin layer (1) is the outermost layer, and the substrate is paper.

[0123] The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples in any way.

[0124] (Evaluation of Water Vapor Barrier Property) The water vapor transmission rate (WVTR) of the laminate was measured by the cup method in accordance with JIS Z 2080 under conditions of a temperature of 40° C. and a relative humidity of 90%, with the coated surface facing inward.

[0125] (Evaluation of oxygen barrier property) The oxygen transmission rate (OTR) of the laminate was measured at 23°C and 50% RH using an oxygen transmission rate measuring device (OX-TRAN2 / 20, manufactured by MOCON Corporation). The oxygen transmission rate (OTR) was also measured at 23°C and 85% RH using the same device.

[0126] The materials used in producing the laminates of the Examples and Comparative Examples are as follows: (Vinyl alcohol-based polymers) PVOH-1: ethylene-modified polyvinyl alcohol having a viscosity-average degree of polymerization of 1,120, a degree of saponification of 98.8 mol%, and an ethylene-modified amount of 6.5 mol% PVOH-2: polyvinyl alcohol having a viscosity-average degree of polymerization of 930 and a degree of saponification of 98.2 mol% PVOH-3: ethylene-modified polyvinyl alcohol having a viscosity-average degree of polymerization of 1,590, a degree of saponification of 97.7 mol%, and an ethylene-modified amount of 4.5 mol% PVOH-4: vinyl alcohol-based polymer ("BVE8049Q" manufactured by Mitsubishi Chemical Corporation)

[0127] (Dispersions containing water-dispersible polymers) St-Acryl Em-1: Dispersion of styrene-acrylic copolymer containing wax ("Joncryl 4130" manufactured by BASF SE, "Joncryl" is a registered trademark) St-Acryl Em-2: Dispersion of styrene-acrylic copolymer containing wax ("XP-8829" manufactured by Seiko PMC Corporation)

[0128] (Urethane polymers, etc.) PU: Urethane polymer ("NeoRez R670XP" manufactured by Covestro AG, "NeoRez" is a registered trademark) PEI: Polyethyleneimine with a number average molecular weight of 70,000 ("Epomin P-1000" manufactured by Nippon Shokubai)

[0129] (Layered inorganic material) Mica: "NTS-10NC" manufactured by Topy Industries, Ltd. (aspect ratio 1,000)

[0130] (Polyethylene) LLDPE film: "LS-76OC" Idemitsu Unitech Co., Ltd. (50 μm)

[0131] Example 1 St-Acryl Em-1 (a dispersion of a styrene-acrylic copolymer containing wax) was prepared as a coating liquid (1) for forming a resin layer (1). A coating liquid (2) for forming a resin layer (2) was prepared by mixing a urethane polymer PU with an aqueous solution of a vinyl alcohol polymer PVOH-1. The content of the urethane polymer in the coating liquid (2) was 5 parts by mass per 100 parts by mass of the vinyl alcohol polymer.

[0132] Basis weight as base material: 80 g / m ２ The coating weight after drying was 3 g / m on bleached kraft paper. ２ The coating solution (2) was applied using a reverse gravure coater so that the coating amount after drying was 13 g / m. ２ The coating liquid (1) was applied using a wire bar so that the thickness of the resin layer (1) was 100° C. and the applied coating liquid (1) was dried at 100° C. for 5 minutes to provide a resin layer (1). In this way, a laminate (substrate / resin layer (2) / resin layer (1)) of Example 1 was obtained.

[0133] The water vapor barrier property (WVTR) of the obtained laminate of Example 1 was 6.4 cc / m ２ / day, oxygen barrier (OTR) at 23°C is 6.4cc / m at 50% humidity. ２ / day, 77.4cc / m at 85% humidity ２ / day.

[0134] Example 2 An aqueous solution of PVOH-1, a vinyl alcohol polymer, was prepared as a coating liquid for forming a filling layer. St-Acryl Em-1 (a dispersion of a styrene-acrylic copolymer containing wax) was prepared as a coating liquid (1) for forming a resin layer (1). A coating liquid (2) for forming a resin layer (2) was prepared by mixing PU, a urethane polymer, with an aqueous solution of PVOH-1, a vinyl alcohol polymer. The content of the urethane polymer in coating liquid (2) was 5 parts by mass per 100 parts by mass of the vinyl alcohol polymer.

[0135] Basis weight as base material: 80 g / m ２ The coating amount after drying was 1 g / m on bleached kraft paper. ２ The coating solution for forming the filler layer was applied using a reverse gravure coater so that the coating amount after drying was 3 g / m. ２ The coating solution (2) was applied using a reverse gravure coater so that the coating amount after drying was 13 g / m. ２ The coating liquid (1) was applied using a wire bar so that the thickness of the resin layer (1) was 100° C. and dried for 5 minutes at 100° C., thereby providing a resin layer (1). In this way, a laminate (substrate / filler layer / resin layer (2) / resin layer (1)) of Example 2 was obtained.

[0136] The water vapor barrier property (WVTR) of the obtained laminate of Example 2 was 7.2 cc / m ２ / day, oxygen barrier (OTR) at 23°C is 1.6cc / m at 50% humidity. ２ / day, 48.2cc / m at 85% humidity ２ / day.

[0137] [Examples 3 to 7, Comparative Example 1] Each laminate (substrate / filler layer / resin layer (2) / resin layer (1)) of Examples 3 to 7 and Comparative Example 1 was obtained in the same manner as in Example 2, except that the type of coating liquid (1) (dispersion containing a water-dispersible polymer), the type of vinyl alcohol-based polymer in coating liquid (2), and the content of the urethane-based polymer (content relative to 100 parts by mass of the vinyl alcohol-based polymer) were changed as shown in Table 1. The water vapor barrier property (WVTR) and oxygen barrier property (OTR) of each obtained laminate were evaluated. The evaluation results are shown in Table 1.

[0138] Example 8 An aqueous solution of PVOH-1, a vinyl alcohol polymer, was prepared as a coating liquid for forming a filling layer. St-Acryl Em-1 (a dispersion of a styrene-acrylic copolymer containing wax) was prepared as coating liquid (1) for forming resin layer (1). PU, a urethane polymer, and mica, an inorganic substance, were mixed with an aqueous solution of PVOH-1, a vinyl alcohol polymer, to prepare coating liquid (2) for forming resin layer (2). The content of the urethane polymer in coating liquid (2) was 5 parts by mass per 100 parts by mass of the vinyl alcohol polymer. The content of the inorganic substance in coating liquid (2) was 10 parts by mass per 100 parts by mass of the vinyl alcohol polymer.

[0139] Basis weight as base material: 80 g / m ２ The coating amount after drying was 1 g / m on bleached kraft paper. ２ The coating solution for forming the filler layer was applied using a reverse gravure coater so that the coating amount after drying was 3 g / m. ２ The coating solution (2) was applied using a reverse gravure coater so that the coating amount after drying was 13 g / m. ２ The coating liquid (1) was applied using a wire bar so that the thickness of the resin layer (1) was 100° C. and dried for 5 minutes at 100° C., thereby providing a resin layer (1). In this way, a laminate (substrate / filler layer / resin layer (2) / resin layer (1)) of Example 8 was obtained.

[0140] The water vapor barrier property (WVTR) of the obtained laminate of Example 8 was 4.3 cc / m ２ / day, oxygen barrier (OTR) at 23°C is 1cc / m at 50% humidity ２ / day or less, 9.8cc / m at 85% humidity ２ / day.

[0141] [Examples 9 to 12] Each laminate (substrate / filler layer / resin layer (2) / resin layer (1)) of Examples 9 to 12 was obtained in the same manner as in Example 8, except that the type of coating liquid (1) (dispersion containing a water-dispersible polymer) and the content of the inorganic substance in coating liquid (2) (content relative to 100 parts by mass of the vinyl alcohol-based polymer) were changed as shown in Table 1. The water vapor barrier property (WVTR) and oxygen barrier property (OTR) of each obtained laminate were evaluated. The evaluation results are shown in Table 1.

[0142] [Example 13] A laminate having a filler layer and a resin layer (2) provided on a substrate was obtained in the same manner as in Example 2. An LLDPE film was placed on the resin layer (2) of the laminate and bonded by thermal lamination to provide a resin layer (1). In this way, a laminate of Example 13 (substrate / filler layer / resin layer (2) / resin layer (1)) was obtained.

[0143] [Comparative Example 2] An attempt was made to produce a laminate of Comparative Example 2 in the same manner as in Example 8, except that the urethane polymer (PU) in the coating liquid (2) was changed to polyethyleneimine (PEI). However, the coating liquid (2) gelled, making it difficult to provide the resin layer (2) by coating, and therefore the production and evaluation of the laminate of Comparative Example 2 were discontinued.

[0144]

[0145] The laminates of Examples 1 to 13, in which the resin layer (1) contained a water vapor barrier resin and the resin layer (2) contained a vinyl alcohol-based polymer and a urethane-based polymer, exhibited high water vapor barrier properties and oxygen barrier properties. Furthermore, in the laminates of these Examples, the resin layer (2) contained 25% by mass or more of a vinyl alcohol-based polymer, which made the resin layer (2) easily soluble in liquids such as water during recycling, and the laminates were designed with recyclability in mind. On the other hand, when the resin layer (2) did not contain a urethane-based polymer, as in Comparative Example 1, the water vapor barrier properties were poor. Furthermore, when the coating liquid (2) contained polyethyleneimine and a layered inorganic material in addition to the vinyl alcohol-based polymer, as in Comparative Example 2, it was difficult to form the resin layer (2).

[0146] The laminate of the present invention can be suitably used as a packaging material such as an oil-resistant sheet, a gas barrier sheet, or a flavor barrier sheet.

Claims

1. A laminate having a substrate, a resin layer (1) and a resin layer (2), wherein the resin layer (1) contains a water vapor barrier resin, the resin layer (2) contains a vinyl alcohol polymer and a urethane polymer, and the content of the vinyl alcohol polymer in the resin layer (2) is 25 mass% or more.

2. The laminate according to claim 1, wherein the resin layer (1) and the resin layer (2) are adjacent to each other.

3. The laminate according to claim 1, comprising the substrate, the resin layer (2) and the resin layer (1) in this order.

4. The laminate according to claim 1, wherein the content of the urethane polymer in the resin layer (2) is 75 parts by mass or less per 100 parts by mass of the vinyl alcohol polymer.

5. The laminate according to claim 1, further comprising a filling layer, said filling layer being adjacent to said substrate.

6. The laminate according to claim 5, wherein the sealing layer contains a vinyl alcohol polymer.

7. The laminate according to claim 1, wherein the resin layer (2) contains an ethylene-modified vinyl alcohol polymer as the vinyl alcohol polymer.

8. The laminate according to claim 1, wherein the resin layer (1) is a layer formed by coating.

9. The laminate according to claim 1, wherein the water vapor barrier resin is a water-dispersible polymer.

10. The laminate according to claim 9, wherein the water-dispersible polymer is at least one selected from the group consisting of olefin-based polymers and styrene-based polymers.

11. The laminate according to claim 9, wherein the resin layer (1) further contains a wax.

12. The laminate according to claim 11, wherein the content of the wax in the resin layer (1) is 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the water-dispersible polymer.

13. The laminate according to claim 11, wherein the wax is at least one selected from the group consisting of paraffin wax, microcrystalline wax, and carnauba wax.

14. The laminate according to claim 1, wherein the water vapor barrier resin is a polyolefin.

15. The laminate according to claim 1, wherein the resin layer (1) is the outermost layer.

16. The laminate according to claim 1, wherein the resin layer (2) contains a layered inorganic material.

17. The laminate according to claim 1, wherein the resin layer (1) is substantially free of layered inorganic materials.

18. The laminate of claim 1, wherein the substrate is paper.

19. An oil-resistant sheet comprising the laminate according to any one of claims 1 to 18.

20. A gas barrier sheet comprising the laminate according to any one of claims 1 to 18.

21. A packaging material comprising the laminate according to any one of claims 1 to 18.

22. A method for producing a laminate according to any one of claims 9 to 13 and 15 to 18, comprising the steps of: applying a coating liquid containing the vinyl alcohol polymer and the urethane polymer, and drying the coating liquid at 60 to 140°C for 1 to 30 minutes to form a resin layer (2); and applying a coating liquid containing the water-dispersible polymer, and drying the coating liquid at 60 to 140°C for 1 to 30 minutes to form a resin layer (1).

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