JP2019151025A - Gas barrier laminate - Google Patents

Abstract

To provide a gas barrier laminate which exhibits excellent gas barrier property even in hot water treatment at lower temperatures or in shorter time.SOLUTION: A laminate contains at least a protective layer (III), a plastic base material (I) and a gas barrier layer (II) in this order, in which (1) the plastic base material (I) contains a resin component and a metal compound and a content of the metal compound is 0.1-20 mass%, (2) the gas barrier layer (II) contains a polycarboxylic acid or its anhydride and is laminated on one surface of the plastic base material (I), and (3) the protective layer (III) contains a resin component having a glass transition temperature of 60°C or higher and is laminated on the other surface of the plastic base material (I).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas barrier laminate that exhibits excellent gas barrier properties.

  Plastic films such as polyamide films are excellent in strength, transparency and moldability, and are therefore used in a wide range of applications as packaging materials. However, these plastic films have a relatively high permeability to oxygen and other gases, so when used for packaging general foods, retort-treated foods, cosmetics, medical supplies, agricultural chemicals, etc., they will pass through the film during long-term storage. The contents may be altered by the gas such as oxygen that has penetrated. For this reason, the plastic film used for these packaging applications is required to have a gas barrier property, and in the packaging of food containing moisture, the gas barrier property under high humidity is also required.

  As a method for imparting a gas barrier property to a plastic film, there is a method of laminating a gas barrier layer on a film, and a method using such a gas barrier layer composed of a polycarboxylic acid polymer and a metal compound is known. Yes. For example, a gas barrier laminate in which a gas barrier layer (II) is laminated on a plastic substrate (I), wherein the plastic substrate (I) is a single layer film, and a metal compound is contained in the film layer. Gas barrier laminate comprising 0.1 to 70% by mass, gas barrier layer (II) containing polycarboxylic acid, and polycarboxylic acid being an olefin-maleic acid copolymer (Patent Document 1) In addition, various gas barrier laminates have been proposed.

Japanese Patent No. 5843988

  However, the conventional gas barrier laminate exhibits a desired gas barrier property only after hydrothermal treatment under relatively severe conditions, for example, 95 ° C. × 30 minutes. If hot water treatment can be performed under milder conditions, it will lead to expanded applications. That is, a material that exhibits a desired gas barrier property under a condition where the hydrothermal treatment temperature is lower and the hydrothermal treatment time is shorter is eagerly desired, but such a material has not yet been developed.

  Accordingly, a main object of the present invention is to provide a gas barrier laminate that exhibits excellent gas barrier properties even at a lower temperature or in a shorter time of hot water treatment.

  As a result of intensive studies in view of the problems of the prior art, the present inventor has found that a laminate formed using a specific material can achieve the above object, and has completed the present invention.

That is, the present invention relates to the following gas barrier laminate.
1. A laminate comprising at least a protective layer (III), a plastic substrate (I) and a gas barrier layer (II) in order,
(1) The plastic substrate (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid or an anhydride thereof and is laminated on one surface of the plastic substrate (I).
(3) The protective layer (III) contains a resin component having a glass transition temperature of 60 ° C. or higher, and is laminated on the other surface of the plastic substrate (I).
A gas barrier laminate characterized by that.
2. Item 2. The gas barrier laminate according to Item 1, wherein the plastic substrate (I) is a polyamide film.
3. Item 3. The gas barrier laminate according to Item 1 or 2, wherein the gas barrier layer (II) further contains a polyalcohol.
4). Item 4. The gas barrier laminate according to any one of Items 1 to 3, wherein the protective layer (III) contains a polyalcohol.
5. Item 5. The gas barrier laminate according to any one of Items 1 to 4, wherein the protective layer (III) has a thickness of 1 µm or less.
6). In an oxygen permeability under an atmosphere of a temperature of 20 ° C. and a relative humidity of 90%, the oxygen permeability after hydrothermal treatment at 80 ° C. × 30 minutes is 100 ml / (m ² · day · MPa) or less, and the temperature is 120 ° C. × Item 6. The gas barrier laminate according to any one of Items 1 to 5, wherein the oxygen permeability after 30 minutes of hot water treatment is 100 ml / (m ² · day · MPa) or less.
7). Item 6. The gas barrier laminate according to any one of Items 1 to 5, which is used for hot water treatment with hot water at a temperature of 30 to 130 ° C.
8). A packaging material comprising the gas barrier laminate according to any one of Items 1 to 7.
9. Item 9. The packaging material according to Item 8, which is used for sealing the contents.

  ADVANTAGE OF THE INVENTION According to this invention, the gas-barrier laminated body which expresses the outstanding gas-barrier property also by a low temperature or a short time hot-water process can be provided.

  In particular, in the present invention, a gas barrier layer (II) containing polycarboxylic acids is laminated on one side of a plastic substrate (I) containing 0.1 to 20% by mass of a metal compound, and the other side is specified. By laminating a protective layer (III) containing a resin having a glass transition temperature of 5%, it is possible to reduce the amount of metal compound eluted into the water from the plastic substrate (I) during the hydrothermal treatment, and the gas barrier layer (II ) And the metal compound (reaction efficiency) can be improved. As a result, the gas barrier layer (II) and the metal compound can proceed with sufficient ion cross-linking reaction even under relatively mild hot water conditions. It becomes possible to express gas barrier properties. In other words, since a sufficient amount of the metal compound can be reacted with the gas barrier layer (II) without performing hydrothermal treatment at a high temperature and for a long time as in the prior art, excellent gas barrier properties can be obtained. .

  Such a gas barrier laminate of the present invention expresses an excellent gas barrier property by low-temperature or short-time hot water treatment, and therefore has a wide range of uses as packaging materials for foods, pharmaceuticals and the like that require hot water treatment. Can be used. In particular, it is suitable for packaging products that are easily altered or deteriorated by high-temperature or long-time hot water treatment. Moreover, since the gas barrier property which the gas-barrier laminated body of this invention expresses is excellent also in high humidity, it is suitable also for the long-term storage in a comparatively severe environment.

It is a schematic diagram which shows the basic layer structure of the gas-barrier laminated body of this invention.

1. Gas barrier laminate The gas barrier laminate (present laminate) of the present invention is a laminate comprising at least a protective layer (III), a plastic substrate (I) and a gas barrier layer (II) in this order.
(1) The plastic substrate (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid or an anhydride thereof and is laminated on one surface of the plastic substrate (I).
(3) The protective layer (III) contains a resin component having a glass transition temperature of 60 ° C. or higher, and is laminated on the other surface of the plastic substrate (I).
It is characterized by that.

  A basic configuration of the laminate of the present invention is shown in FIG. In the laminate 10 of the present invention, a gas barrier layer 12 is laminated on one surface of a plastic substrate 11, and a protective layer 13 is laminated on the other surface. Thus, the laminate 10 of the present invention has “protective layer 13 / plastic base material 11 / gas barrier layer 12” as a basic configuration. Each of these layers may be laminated so as to be in direct contact with each other, or may be laminated via another layer (for example, an adhesive layer) as necessary. In particular, in the present invention, the gas barrier layer 12 is preferably laminated so as to be in direct contact with the plastic substrate 11.

  The laminate of the present invention has a layer structure including “protective layer 13 / plastic base material 11 / gas barrier layer 12”, and other layers are laminated on the surface of protective layer 13 and / or gas barrier layer 12 as necessary. May be. Examples of other layers include a printing layer, an adhesive layer, a heat seal layer, and a metal foil layer. Hereinafter, each layer which comprises this invention laminated body is demonstrated.

(1) Plastic substrate (I)
The plastic substrate (I) contains a resin component (hereinafter also referred to as “resin component A”) and a metal compound, and contains 0.1 to 20% by mass of the metal compound. In particular, in the present invention, a molded body (such as a sheet) formed by molding a mixture (particularly a melt-kneaded product) containing the resin component A and the metal compound can be suitably used as the plastic substrate (I).

  As the resin component A, either a thermoplastic resin or a thermosetting resin can be used. In the present invention, a thermoplastic resin can be particularly preferably used. The thermoplastic resin is not particularly limited. For example, a) polyolefin resin such as polyethylene and polypropylene, b) polyamide resin such as nylon 6, nylon 66, nylon 46, nylon MXD6 and nylon 9T, c) polyethylene terephthalate, polyethylene iso Phthalate, polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polyester resin such as polylactic acid, d) Other resins (vinyl chloride resin, polystyrene resin, polycarbonate resin, poly Arylate resin, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, etc.), e) mixtures of a) to d), and the like.

  In the present invention, among thermoplastic resins, polyamide resin is preferable, and nylon 6 is particularly preferable. When using the polyamide resin, when the laminate of the present invention is subjected to wet heat treatment or hydrothermal treatment, the gas barrier property can be further strengthened by the reaction of the metal compound in the plastic substrate (I) and the gas barrier layer (II), When a packaging material (particularly a packaging bag) is constituted by the laminate of the present invention, it is possible to obtain superior piercing strength, impact resistance, and the like. A polyamide resin can be used by 1 type, or 2 or more types of mixtures.

  The content of the resin component A in the plastic substrate (I) can be appropriately set according to the type of the resin component to be used, etc., but is usually about 70 to 100% by mass, particularly 80 to 99% by mass. preferable. Moreover, when using a polyamide resin as the resin component A, the content rate of the polyamide resin in the resin component A is generally 80 to 100% by mass, and particularly preferably 90 to 99% by mass.

  The metal constituting the metal compound is not particularly limited, and examples thereof include monovalent metals such as lithium, sodium, potassium, rubidium, and cesium, magnesium, calcium, zirconium, zinc, copper, cobalt, iron, nickel, aluminum, and the like. A bivalent or higher metal is mentioned. The type of metal is not limited to one, and may be two or more.

  Among these, a metal having a high ionization tendency is preferable in that it easily reacts with polycarboxylic acids. From the viewpoint of gas barrier properties, monovalent or divalent metals are preferred. Accordingly, for example, at least one of lithium, sodium, potassium, magnesium, calcium and zinc is preferable, and at least one of magnesium, calcium and zinc is particularly preferable.

  In the present invention, the metal compound is not particularly limited as long as it is a compound containing the above metal. For example, oxides, hydroxides, halides, inorganic acid salts (carbonates, hydrogen carbonates, phosphates, sulfates, etc.), organic acid salts (carboxylates (acetates, formates, stearates, Citrate, malate, maleate), sulfonate, etc.). In the present invention, oxides or carbonates are particularly preferable in terms of exhibiting excellent gas barrier properties.

  Among the above metal compounds, preferred examples include lithium carbonate, sodium hydrogen carbonate, magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium oxide, calcium carbonate, calcium hydroxide, calcium chloride, calcium phosphate, calcium sulfate, acetic acid. There may be mentioned at least one of calcium, zinc acetate, zinc oxide, zinc carbonate and the like.

  From the viewpoint of gas barrier properties, a divalent metal compound is preferable, and at least one of a magnesium compound, a calcium compound, and a zinc compound is particularly preferable. Therefore, for example, at least one of magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium acetate, calcium oxide, calcium carbonate, calcium acetate, zinc oxide and zinc acetate can be suitably used. Further, from the viewpoint of the transparency of the plastic substrate (I), at least one of a monovalent metal compound and a divalent metal compound is preferable, and at least one of an alkali metal compound and an alkaline earth metal compound is more preferable. Therefore, for example, at least one of lithium carbonate, sodium hydrogen carbonate, magnesium oxide, magnesium carbonate, and magnesium hydroxide can be suitably used.

  Although the form (property) of a metal compound is not limited, it is usually preferable that it is a powder form. That is, it is preferable to adopt a configuration in which metal compound particles are dispersed in the plastic substrate (I). More specifically, a structure in which metal compound particles (powder) are dispersed in a matrix containing the resin component A is preferable.

  The average particle size in this case is not particularly limited, but it may be usually about 0.001 to 10 μm, particularly preferably 0.005 to 5 μm, more preferably 0.01 to 2 μm, Among these, it is most preferable to set it as 0.05-1 micrometer. From the standpoint that the haze of the plastic substrate (I) can be reduced, it is preferable that the average particle size is smaller. However, when the average particle size is less than 0.001 μm, the surface area is large, so that the particles easily aggregate. When coarse aggregates are scattered in the film, the mechanical properties of the substrate may be lowered. The plastic base material (I) containing a metal compound having an average particle size exceeding 10.0 μm has a high frequency of breakage during film formation, and there is a concern that productivity may be reduced.

  The metal compound can be subjected to surface treatment (surface film formation treatment) as necessary. Thereby, dispersibility, weather resistance, wettability with a thermoplastic resin, heat resistance, transparency and the like can be improved. As the surface treatment, a known inorganic treatment or organic treatment can be adopted. Examples of the inorganic treatment include a treatment of forming alumina, silica, titania, zirconia, tin oxide, antimony oxide, zinc oxide or the like on the particle surface of the metal compound. Examples of the organic treatment include fatty acid compounds, polyol compounds such as pentaerythritol and trimethylolpropane, amine compounds such as triethanolamine and trimethylolamine, silicone compounds such as silicone resins and alkylchlorosilanes on the surface of metal compound particles. The process to form is mentioned.

  The content of the metal compound in the plastic substrate (I) is usually 0.1 to 20% by mass, particularly preferably 0.1 to 15% by mass, and further 0.2 to 10% by mass. Of these, 0.2 to 5% by mass is most preferable. From the viewpoint of haze, it is preferably 5% by mass or less. When the content of the metal compound in the plastic substrate (I) is 0.1 to 20% by mass, excellent gas barrier properties can be obtained. On the other hand, when the content of the metal compound in the plastic substrate (I) is less than 0.1% by mass, the number of ion-crosslinked structures formed by reacting with the polycarboxylic acids in the gas barrier layer (II) decreases. The desired gas barrier property cannot be obtained. On the other hand, the plastic substrate (I) having the content of more than 20% by mass has a high frequency of breaking in stretching during film formation, and the productivity tends to be lowered, and the mechanical properties are also likely to be lowered.

  In the plastic substrate (I) (especially thermoplastic resin), in the range that does not adversely affect the performance of the plastic substrate (I), for example, heat stabilizer, antioxidant, reinforcing material, pigment, deterioration inhibitor, You may add 1 type, or 2 or more types of various additives, such as a weathering agent, a flame retardant, a plasticizer, antiseptic | preservative, a ultraviolet absorber, an antistatic agent, and an antiblocking agent, as needed. In addition, an inorganic or organic lubricant other than the metal compound may be added for the purpose of improving the slip property of the plastic substrate (I). For example, silica can be suitably added as a lubricant. These additives may be added to the mixture (especially melt-kneaded product) as well as the metal compound.

  The thickness of the plastic substrate (I) is not particularly limited, and can be appropriately selected according to, for example, the mechanical strength required for the obtained gas barrier laminate. In particular, the thickness of the plastic substrate (I) is preferably preferably 5 to 100 μm, more preferably 10 to 30 μm, for reasons such as securing mechanical strength and ease of handling. When the thickness of the plastic substrate (I) is less than 5 μm, sufficient mechanical strength cannot be obtained, and the puncture strength may be reduced.

(2) Gas barrier layer (II)
The gas barrier layer (II) contains a polycarboxylic acid or an anhydride thereof (in the present invention, both are collectively referred to as “polycarboxylic acids”) and on one surface of the plastic substrate (I). Are stacked.

  The polycarboxylic acids contained in the gas barrier layer (II) play a role of developing gas barrier properties by reacting with the metal compound in the plastic substrate (I).

  Polycarboxylic acids are compounds having two or more carboxyl groups in the molecule or their anhydrides. In the case of an anhydride, all the carboxyl groups may have an anhydride structure [—CO—O—CO—], or a part of the carboxyl groups may have an anhydride structure. Further, the polycarboxylic acids may be in any form of a monomer or a polymer.

  Specific examples of polycarboxylic acids include a) monomer compounds such as 1,2,3,4-butanetetracarboxylic acid, b) polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymer, acrylic (Meth) acrylic acid homopolymer or copolymer such as acid-maleic acid copolymer, acrylic acid-maleic anhydride copolymer, d) polymaleic acid, ethylene-maleic acid copolymer, ethylene-maleic anhydride Examples thereof include olefin-maleic acid copolymers such as copolymers, e) polysaccharides having a carboxyl group in the side chain such as alginic acid, and f) polyamides or polyesters having a carboxyl group. These polycarboxylic acids can be used alone or in combination of two or more. The “(meth) acrylic acid” is a generic term for acrylic acid or methacrylic acid (the same applies hereinafter).

  When the polycarboxylic acid is a polymer, its weight average molecular weight is not particularly limited, but is generally preferably 1,000 to 1,000,000, particularly 10,000 to 150,000. Is more preferable, and it is most preferable that it is 15,000-110,000 among them. If the weight average molecular weight of the polycarboxylic acid is too low, the resulting gas barrier layer (II) becomes fragile. On the other hand, if the molecular weight is too high, handling properties are impaired, and in some cases, a gas barrier layer (II) described later is formed. Therefore, the gas barrier properties of the resulting gas barrier layer (II) may be impaired.

  In the present invention, it is preferable to use an olefin-maleic acid copolymer as the polycarboxylic acid, and it is more preferable to use an ethylene-maleic acid copolymer (hereinafter also referred to as “EMA”). By using EMA, more excellent gas barrier properties can be obtained. As the EMA itself, a known or commercially available EMA can be used. Moreover, what was obtained by the well-known manufacturing method can also be used. Therefore, for example, a copolymer obtained by polymerization using maleic anhydride and ethylene by a method such as solution radical polymerization can also be used.

  The maleic acid unit in EMA is preferably 5 mol% or more, more preferably 20 mol% or more, further preferably 30 mol% or more, and most preferably 35 mol% or more. . In addition, the maleic acid unit in the olefin-maleic acid copolymer is likely to have a maleic anhydride structure in which the adjacent carboxyl group is dehydration-cyclized in a dry state, and is ring-opened into a maleic acid structure when wet or in an aqueous solution. . Therefore, in the present invention, unless otherwise specified, maleic acid units and maleic anhydride units are collectively referred to as “maleic acid units”.

  The weight average molecular weight of EMA may be usually about 1,000 to 1,000,000, preferably 3,000 to 500,000, more preferably 7,000 to 300,000, Most preferably, it is 10,000 to 200,000.

  The content of the polycarboxylic acid in the gas barrier layer (II) is not particularly limited and can be appropriately set according to the type of the polycarboxylic acid to be used, but is usually 40 to 90 from the viewpoint of obtaining higher gas barrier properties. It is preferable to set it as about mass%, and it is more preferable to set it as 50-80 mass% especially.

  In addition to polycarboxylic acids, the gas barrier layer (II) in the laminate of the present invention may contain other components (particularly components that react with polycarboxylic acids to crosslink polycarboxylic acids). For example, the laminate of the present invention preferably contains polyalcohol or the like.

  By incorporating a polyalcohol in the gas barrier layer (II), higher gas barrier properties can be obtained. That is, the polycarboxylic acids in the gas barrier layer (II) can undergo an ester crosslinking reaction with a polyalcohol in addition to an ionic crosslinking reaction with the metal compound (metal ion) in the plastic substrate (I). Can be further improved.

  The polyalcohol is a compound having two or more hydroxyl groups in the molecule, and as long as it is a low molecular compound or a polymer compound (polymer). Examples include sugar alcohols such as glycerin and pentaerythritol, monosaccharides such as glucose, disaccharides such as maltose, and oligosaccharides such as galactooligosaccharide. Examples of the polymer compound include polysaccharides such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and starch. The above polyalcohols can be used alone or in combination of two or more.

  The degree of saponification when the polyalcohol is polyvinyl alcohol, an ethylene-vinyl alcohol copolymer or the like is not limited, but is usually preferably 95 mol% or more, more preferably 98 mol% or more. Is preferable. The average degree of polymerization is preferably 50 to 2,000, and more preferably 200 to 1,000. Thereby, more excellent gas barrier properties can be obtained.

  The content of the polyalcohol is not limited, but in particular, there are two OH groups contained in the polyalcohol and two COOH groups contained in the polycarboxylic acid (in the case of anhydride, [—CO—O—CO—]). The molar ratio (OH group / COOH group) with respect to COOH group in the above formula may be set to 0.01 to 20, but preferably 0.01 to 10. Furthermore, it is more preferable to set it as 0.02-5, and it is most preferable to set it as 0.04-2 among them. As a result, the gas barrier property can be further enhanced.

  In the gas barrier layer (II), for example, a heat stabilizer, an antioxidant, a reinforcing material, a pigment, a deterioration inhibitor, a weathering agent, Additives such as flame retardants, plasticizers, mold release agents, lubricants, preservatives, antifoaming agents, wetting agents, viscosity modifiers may be added.

  Examples of heat stabilizers, antioxidants, and deterioration inhibitors include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like. Also good.

  Examples of the reinforcing material include clay, talc, wollastonite, silica, alumina, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, zeolite, montmorillonite, hydrotalcite, fluoromica, metal Examples thereof include fibers, metal whiskers, ceramic whiskers, potassium titanate whiskers, boron nitride, graphite, glass fibers, carbon fibers, fullerenes (C60, C70, etc.), carbon nanotubes, and the like.

  The thickness of the gas barrier layer (II) is preferably 0.05 μm or more in order to more reliably obtain the gas barrier property of the gas barrier laminate. The upper limit of the thickness is not particularly limited, but is preferably about 5 μm from the standpoint of economy.

(3) Protective layer (III)
The protective layer (III) contains a resin component having a glass transition temperature (Tg) of 60 ° C. or higher, and is laminated on the other surface of the plastic substrate (I). As shown in FIG. 1, the protective layer (III) is preferably laminated on the entire opposite surface of the plastic substrate (I) on which the gas barrier layer (II) is laminated. By forming the protective layer (III), elution of the metal compound in the plastic substrate (I) to the outside of the gas barrier laminate can be effectively suppressed during the hydrothermal treatment. As a result, the reactivity between the metal compound and the gas barrier layer (II) is increased, and excellent gas barrier properties can be stably obtained even in hot water treatment at a lower temperature and for a shorter time.

  The protective layer (III) contains a resin component having a glass transition temperature of 60 ° C. or higher (hereinafter also referred to as “resin component B”), and the glass transition temperature of the resin component B is preferably 80 ° C. or higher. In particular, the temperature is more preferably 100 ° C. or higher. When the glass transition temperature of the resin component B is less than 60 ° C., the elution suppression effect of the metal compound in the plastic substrate (I) is small, and a desired gas barrier property can be obtained by hydrothermal treatment at a relatively low temperature and in a short time. May be difficult. The upper limit of the glass transition temperature is, for example, about 150 ° C. and can be about 130 ° C., but is not limited thereto.

  The content of the resin component B in the protective layer (III) is not limited, but is usually preferably 20% by mass or more, and more preferably 30% by mass or more. When the content of the resin component B is less than 20% by mass, the above effects may not be obtained. The upper limit of the content of the resin component B is not limited, but is usually about 100% by mass, preferably 95% by mass. Therefore, it can be set to, for example, 25 to 100% by mass, or, for example, 90 to 100% by mass.

  Examples of the resin component B include various resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, urethane resin, polyester resin, acrylic resin, epoxy resin, alkyd resin, melamine resin, amino resin, and olefin resin. Of these, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are preferable from the viewpoint of barrier properties. In addition, a urethane resin is preferable from the viewpoint of water resistance, solvent resistance, heat resistance, and curing temperature, and among them, a urethane resin having self-crosslinking property is preferable. The above resin components can be used alone or in combination of two or more.

  The protective layer (III) preferably contains polyvinyl alcohol. By containing polyvinyl alcohol, gas barrier properties are imparted to the protective layer (III), so that the gas barrier properties of the gas barrier laminate are further improved.

  Any type of polyvinyl alcohol can be used, and in particular, those having the following physical properties can be preferably used. That is, the saponification degree of polyvinyl alcohol is preferably 95 mol% or more, and more preferably 98 mol% or more. The average degree of polymerization is usually preferably 50 to 2,000, and more preferably 200 to 1,000. As such polyvinyl alcohol itself, a known or commercially available product can be used.

  In addition to the resin component B, the protective layer (III) can contain other additives as required. Examples of the additive include the same additive as in the gas barrier layer (II).

  In addition, a compound that acts as a crosslinking agent may be added as an additive. Thereby, the water resistance, solvent resistance, heat resistance, etc. of the protective layer (III) can be further enhanced. Examples of such compounds include isocyanate compounds, melamine compounds, urea compounds, epoxy compounds, carbodiimide compounds, zirconium salt compounds such as ammonium zirconium carbonate, and metal alkoxides. These compounds can be used alone or in combination of two or more. In particular, when polyvinyl alcohol is contained as the resin component B, it is preferable to mix a compound having a plurality of hydroxyl groups (preferably about 500 to 10,000) in the molecule with a hydroxyl group and an ester crosslinking reaction as a crosslinking agent. When the crosslinking agent is used, the content thereof is not limited, but in general, it may be appropriately set within a range of about 1 to 500 parts by mass with respect to 100 parts by mass of the resin component B.

  In the present invention, the thickness of the protective layer (III) is preferably 0.05 to 5 μm, more preferably 0.1 to 3 μm, more preferably 0 to 3 μm from the viewpoint of enhancing the elution suppression effect of the metal compound. Most preferably, the thickness is 2 to 2 μm.

(4) Other layers In the laminate of the present invention, a structure including a protective layer, a plastic substrate, and a gas barrier layer is a basic structure, but other layers are provided on the surface of the protective layer and / or the gas barrier layer as necessary. One layer or two or more layers may be laminated. Examples of other layers include a printing layer, an adhesive layer, a heat seal layer, a metal foil layer, a primer layer, an anchor coat layer, and a metal vapor deposition layer.

2. Physical Properties of Gas Barrier Laminate The laminate of the present invention is basically provided in the form of a sheet. Although the total thickness can be appropriately set according to the application, etc., it can usually be appropriately set within a range of 5 to 50 μm, and preferably 10 to 35 μm.

  The laminate of the present invention is a metal compound that can be eluted from the plastic substrate (I) particularly when the laminate of the present invention is subjected to hydrothermal treatment since the protective layer is formed on the surface of the plastic substrate. The amount can be suppressed. More specifically, the amount of the metal compound eluted when the laminate of the present invention (preferably one that has not been immersed in water yet) is subjected to hydrothermal treatment at 120 ° C. for 30 minutes (before hydrothermal treatment). The rate of decrease with respect to is usually preferably 20% by mass or less, more preferably 15% by mass or less, and most preferably 10% by mass or less. When the amount of the eluted metal compound exceeds 20% by mass, the reactivity between the metal compound and the gas barrier layer (II) is lowered, and the desired gas barrier property is not exhibited in the hot water treatment at a lower temperature and in a shorter time. The lower limit of the reduction rate is most preferably 0% by mass, but may be, for example, about 1% by mass or about 5% by mass.

The laminate of the present invention (preferably one that has not yet been immersed in water) has an oxygen permeability of 80 ° C. × 30 minutes after hydrothermal treatment at an oxygen permeability of 20 ° C. and a relative humidity of 90%. The oxygen permeability after hydrothermal treatment at 120 ° C. for 30 minutes is 100 ml / (m ² · day · MPa) or less, and in particular, both oxygen permeability is 50 ml / (m ² · day · MPa) or less. More preferably, it is more preferably 20 ml / (m ² · day · MPa) or less, and most preferably 10 ml / (m ² · day · MPa) or less. Both oxygen permeability may be the same as each other, or may be different from each other. In addition, the lower limit value of both oxygen permeability is not limited, but may be usually about 0.01 ml / (m ² · day · MPa).

  The laminate of the present invention preferably has a tensile strength of 150 MPa or more, more preferably 180 MPa or more. If the tensile strength is less than 150 MPa, the mechanical strength is not sufficient, and the piercing strength tends to decrease. Further, the tensile elongation is preferably 60% or more, more preferably 80% or more, from the same viewpoint as the tensile strength.

  The pinhole resistance of the laminate of the present invention is preferably 100 or less, and more preferably 20 or less, in the number of occurrences of pinholes in a 500 times repeated bending fatigue test at 5 ° C .. Specifically, the pinhole resistance is Fed. Shown in MIL-B-131F. Test Method Std. In accordance with Method 2017 of 101C, a sample of 12 inches × 8 inches is gripped in a cylindrical shape with a diameter of 3.5 inches, with an initial gripping distance of 7 inches and a gripping distance of 1 inch at maximum bending, a so-called gel bot tester (manufactured by Rigaku Corporation) The number of occurrences of pinholes after bending 500 times under the condition of 5 ° C. was measured and evaluated.

  Regarding the transparency of the laminate of the present invention, the haze is preferably 70% or less, particularly preferably 50% or less, more preferably 30% or less, and particularly preferably 15% or less. Most preferably, it is 10% or less. However, this is not the case because transparency may not be required depending on the application.

3. Production of Gas Barrier Laminate The production method of the inventive laminate is not particularly limited. For example, a) a method in which a sheet is laminated by forming a mixture containing components that can constitute each layer, and b) each layer. It can be suitably carried out by any one of a method of laminating a coating film with a coating liquid containing components that can be constituted, c) a method of combining a) and b), and the like.

  In particular, in the present invention, an unstretched film containing a resin component A and a metal compound (powder) is used as a precursor for a plastic substrate (I), and a gas barrier layer (II) forming coating solution is formed on one side of the unstretched film. A method comprising a step of forming a coating film by the step of forming a coating film by the coating liquid for forming the protective layer (III) on the other surface, and a step of stretching an unstretched film after the coating film has been formed Can be adopted.

  In this case, as a method for stretching the unstretched film, either uniaxial stretching or biaxial stretching can be employed. In the case of biaxial stretching, either simultaneous biaxial stretching or sequential biaxial stretching can be employed.

  Although the draw ratio in the case of extending | stretching is not specifically limited, It can set as follows. In the case of uniaxial stretching, it is preferably 1.5 times or more, more preferably 2 to 6 times. In the case of biaxial stretching, it is preferably 1.5 times or more in the vertical and horizontal directions, more preferably 2 to 4 times. In addition, the area magnification is usually preferably 3 times or more, more preferably 6 to 20 times, and most preferably 6.5 to 13 times. By setting the draw ratio within the above range, it is possible to obtain a gas barrier laminate that can exhibit more excellent mechanical properties.

  In this invention, when employ | adopting biaxial stretching, the following methods can be used suitably by either simultaneous biaxial stretching or sequential biaxial stretching.

  The first method (in the case of simultaneous biaxial stretching) is a method for producing a gas barrier laminate, and (1) for forming a gas barrier layer (II) on one side of an unstretched film containing a resin component A and a metal compound. Step of applying coating liquid (gas barrier layer (II) forming step), (2) Step of applying protective layer (III) forming coating liquid on the other surface of the unstretched film (protective layer (III) formation) (Step), (3) The laminate of the present invention can be suitably produced by a method including a step (stretching step) of simultaneously biaxially stretching an unstretched film coated with at least one of the two coating liquids. .

  The second method (in the case of sequential biaxial stretching) is a method for producing a gas barrier laminate, and (1) a step of stretching an unstretched film containing a resin component A and a metal compound in the machine direction (MD). (First stretching step), (2) A gas barrier layer (II) forming coating solution is applied to one side of a film stretched in the longitudinal direction, and a protective layer (III) forming coating solution is applied to the other side. The present invention laminate can be suitably produced by a method comprising a step (coating film forming step) and (4) a step (second stretching step) of stretching the film coated with both coating solutions in the transverse direction. it can.

  In particular, in the present invention, it is preferable to employ the first method (simultaneous biaxial stretching). The simultaneous biaxial stretching method can generally have practical characteristics such as mechanical characteristics, optical characteristics, thermal dimensional stability, and pinhole resistance. On the other hand, in the sequential biaxial stretching method in which the transverse stretching is performed after the longitudinal stretching, the orientation crystallization of the film proceeds during the longitudinal stretching and the stretchability of the thermoplastic resin during the transverse stretching decreases, thereby When the blending amount is large, the breaking frequency of the film tends to increase. For this reason, in this invention, it is preferable to take the simultaneous biaxial stretching method. Therefore, in the following, the first method will be described more specifically as a representative example of the method for producing the laminate of the present invention.

(1) Gas barrier layer (II) formation process In a gas barrier layer (II) formation process, the coating liquid for gas barrier layer (II) formation is apply | coated to the single side | surface of the unstretched film containing the resin component A and a metal compound.

  The unstretched film used at this process is not specifically limited, For example, it can manufacture by shape | molding the mixture containing a resin component (thermoplastic resin) and a metal compound in a sheet form or a film form.

  The method for preparing the mixture is not particularly limited. For example, a) a method of adding a metal compound when synthesizing (polymerizing) a resin component (especially a thermoplastic resin), b) a method of kneading the resin component and the metal compound with an extruder, c) a high metal compound Examples include a method (master batch method) in which a master batch blended by kneading to a concentration is produced, and this is added to a thermoplastic resin and diluted. In the present invention, the masterbatch method is preferably employed in terms of easy adjustment of the content of the metal compound and excellent operability.

  The molding method is not particularly limited, and a known molding method such as press molding, extrusion molding, injection molding, or the like can be employed. For example, a mixture containing a resin component (thermoplastic resin) and a metal compound is heated and melted with an extruder and extruded into a film form from a T die, and rotated by a known casting method such as an air knife casting method or an electrostatic application casting method. An unstretched film can be obtained by cooling and solidifying on a cooling drum. If the unstretched film is oriented, the stretchability may be lowered in the subsequent step. Therefore, the unstretched film is preferably in an amorphous and non-oriented state.

  In addition, what is necessary is just to make it the same as the content shown by said "1. gas-barrier laminated body", a kind, content, etc. of a thermoplastic resin, a metal compound, and another additive.

  Here, when a polyamide resin is used as the thermoplastic resin, the obtained unstretched film is transferred to a water tank temperature-controlled so as not to exceed 80 ° C., and subjected to a water immersion treatment within 5 minutes, 0.5 to 15 % Moisture absorption treatment is preferred.

  In this step, the gas barrier layer (II) forming coating solution is applied to the unstretched film as described above so as to come into contact with the surface of the unstretched film.

  The coating liquid for forming the gas barrier layer (II) can be prepared by dissolving or dispersing the components constituting the gas barrier layer (II) in a solvent.

  As the solvent, various organic solvents can be used in addition to water. Examples of the organic solvent include hydrocarbon solvents such as cyclohexane, normal hexane, and benzene, alcohol solvents such as methanol, ethanol, propanol, isopropyl alcohol, and isobutyl alcohol, ketone solvents such as acetone, ketone, and methyl ethyl ketone, methyl acetate, Examples thereof include ester solvents such as ethyl acetate, isopropyl acetate, isobutyl acetate and isopentyl acetate, and ether solvents such as ethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate and ethylene glycol monomethyl ether. Among these, at least one of water and a water-soluble organic solvent is preferable, and water is particularly preferable. When water is used, the coating solution is preferably in the form of an aqueous solution or an aqueous dispersion (that is, an aqueous coating solution), and particularly at least a polycarboxylic acid (or at least one polyalcohol and a polycarboxylic acid). More preferably, it is in the form of an aqueous solution dissolved in water.

  Moreover, when preparing the coating liquid for gas barrier layer (II) formation, it is preferable to add 0.1-20 equivalent% alkali compound with respect to the carboxyl group of polycarboxylic acids. Polycarboxylic acids have high hydrophilicity when the carboxyl group content is high, so they can be made into an aqueous solution without adding an alkali compound, but the gas barrier properties obtained by adding an appropriate amount of an alkali compound can be obtained. The gas barrier property of the laminate can be significantly improved. In this case, the alkali compound only needs to be capable of neutralizing the carboxyl group of the polycarboxylic acid, and examples thereof include sodium hydroxide. Moreover, it is preferable to set the addition amount of an alkali compound so that it may become 0.1-20 mol% with respect to the carboxyl group of polycarboxylic acids.

  The coating liquid for forming the gas barrier layer (II) can be prepared by a known method using, for example, a dissolution vessel equipped with a stirrer. For example, a method in which polycarboxylic acids and polyalcohol are separately made into aqueous solutions and mixed before coating is preferable. At this time, if the alkali compound is added to an aqueous solution of polycarboxylic acids, the stability of the aqueous solution can be improved.

  The method for applying the gas barrier layer (II) forming coating solution is not particularly limited. For example, an air knife coater, a kiss roll coater, a metering bar coater, a gravure roll coater, a reverse roll coater, a dip coater, a die coater, or the like, or a method combining any of these can be used.

  After applying the gas barrier layer (II) forming coating solution, it may be naturally dried, if necessary, and may be dried by heating. The drying method by heating is not particularly limited, and examples thereof include a method of forming a gas barrier layer (II) as a dry film by evaporating moisture or the like by blowing hot air with a dryer or the like, or infrared irradiation.

  Although the drying temperature in the case of heat-drying can be suitably set, for example by the presence or absence of an additional component, its content, etc., Usually, it is about 50-200 degreeC, It is preferable that it is especially 80-150 degreeC, Furthermore, 100-120 More preferably, it is ° C. If the drying temperature is too low, the formation time of the dry film becomes long and the productivity decreases. On the other hand, if the drying temperature is too high, the plastic substrate (I), the gas barrier layer (II) and the like may become brittle. In addition, heat drying can be implemented in the temperature range lower than the temperature of the heat processing (heat setting) of a extending process, for example.

  Moreover, when apply | coating the coating liquid for gas barrier layer (II) formation, high energy beam irradiation, such as an ultraviolet-ray, an X-ray, an electron beam, may be given before and after the drying as needed. In such a case, the component which bridge | crosslinks or superposes | polymerizes by high energy ray irradiation may be mix | blended.

(2) Protective layer (III) forming step In the protective layer (III) forming step, a protective layer (III) forming coating solution is applied to the other surface of the unstretched film.

  The coating liquid for forming the protective layer (III) can be prepared by dissolving or dispersing the components constituting the protective layer (III) in a solvent.

  As the solvent, various organic solvents can be used in addition to water. Examples of the organic solvent include hydrocarbon solvents such as cyclohexane, normal hexane, and benzene, alcohol solvents such as methanol, ethanol, propanol, isopropyl alcohol, and isobutyl alcohol, ketone solvents such as acetone, ketone, and methyl ethyl ketone, methyl acetate, Examples thereof include ester solvents such as ethyl acetate, isopropyl acetate, isobutyl acetate and isopentyl acetate, and ether solvents such as ethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate and ethylene glycol monomethyl ether. Among these, at least one of water and a water-soluble organic solvent is preferable, and water is particularly preferable. When water is used, the coating liquid is preferably in the form of an aqueous solution or an aqueous dispersion (that is, an aqueous coating liquid), and more preferably in the form of an aqueous solution in which at least the resin component B is dissolved in water. .

  The coating solution for forming the protective layer (III) can be prepared by a known method using, for example, a dissolution vessel equipped with a stirrer. Although the density | concentration of the resin component B in the coating liquid in this case is not specifically limited, For example, it can set suitably in 5-30 mass%.

  The method for applying the protective layer (III) forming coating solution is not particularly limited. For example, an air knife coater, a kiss roll coater, a metering bar coater, a gravure roll coater, a reverse roll coater, a dip coater, a die coater, or the like, or a method combining any of these can be used.

  After applying the coating liquid for forming the protective layer (III), it may be naturally dried as necessary, but drying by heating can also be carried out. The drying method by heating is not particularly limited, and examples thereof include a method of forming a gas barrier layer (II) as a dry film by evaporating moisture or the like by blowing hot air with a dryer or the like, or infrared irradiation.

  Although the drying temperature in the case of heat-drying can be suitably set, for example by the presence or absence of an additional component, its content, etc., Usually, it is about 50-200 degreeC, It is preferable that it is especially 80-150 degreeC, Furthermore, 100-120 More preferably, it is ° C. If the drying temperature is too low, the formation time of the dry film becomes long and the productivity decreases. On the other hand, if the drying temperature is too high, the plastic substrate (I), the gas barrier layer (II) and the like may become brittle. In addition, heat drying can be implemented in the temperature range lower than the temperature of the heat processing (heat setting) of a extending process, for example.

  Moreover, when apply | coating the coating liquid for protective layer (III) formation, high energy beam irradiation, such as an ultraviolet-ray, an X-ray, an electron beam, may be given before and after the drying as needed. In such a case, the component which bridge | crosslinks or superposes | polymerizes by high energy ray irradiation may be mix | blended.

(3) Stretching step In the stretching step, the unstretched film coated with the two coating liquids is stretched. That is, the laminate of the present invention can be more suitably obtained by a so-called in-line coating method. By using the in-line coating method, the heat treatment necessary for stretching and heat setting of the film and the heat treatment to the gas barrier layer (II) and protective layer (III) can be performed simultaneously and at a relatively high temperature. Efficiency can be increased. On the other hand, when the gas barrier layer (II) and protective layer (III) are applied to the stretched film and subjected to heat treatment (in the case of the so-called off-line coating method), after further application to the stretched film that has been subjected to the heat treatment in the stretching step Therefore, the plastic base material (I) becomes brittle due to excessive heat, and the strength and elongation of the plastic substrate may decrease.

  In the present invention, the stretching may be either uniaxial stretching or biaxial stretching, but biaxial stretching is particularly preferable. In the case of biaxial stretching, either sequential biaxial stretching or simultaneous biaxial stretching may be used. For example, an unstretched film coated with both coating solutions was simultaneously biaxially stretched by simultaneously biaxially stretching in the machine direction (MD) and the transverse direction (TD) with a tenter simultaneous biaxial stretcher. A gas barrier laminate can be obtained. Also, for example, after stretching an unstretched film coated with both coating solutions in the machine direction (MD), the gas barrier layer (II) and the protective layer (III) are formed by the method described above, and then the transverse direction (TD) By extending | stretching to, the gas-barrier laminated body by which biaxial stretching was carried out sequentially can be obtained. In particular, in the first method, simultaneous biaxial stretching can be suitably employed as described above.

  Further, the draw ratio of the unstretched film is preferably 1.5 times or more in the machine direction (MD) and the transverse direction (TD), and more preferably 2 to 4 times. The area magnification is usually preferably 3 times or more, more preferably 6 to 20 times, and most preferably 6.5 to 13 times. By setting the draw ratio within the above range, a gas barrier laminate having more excellent mechanical properties can be obtained.

  As for the temperature condition in the stretching step, for example, when performing the above-mentioned simultaneous biaxial stretching, it is usually preferable to stretch in a temperature range of 100 to 250 ° C (preferably 150 to 200 ° C). By controlling in such a temperature range, the film of the present invention can be produced more reliably. These temperatures and the like can be set and controlled while preheating, for example, with a preheating roll, a preheating zone or the like of a stretching apparatus.

  The film that has undergone the stretching process is generally heat-set at a temperature of 100 to 300 ° C. (especially 150 to 300 ° C.) in the tenter where the stretching treatment has been performed, and 0 to 10%, preferably 2 to 6%, as necessary. In the range, the longitudinal and / or lateral relaxation treatment is performed. In order to reduce the heat shrinkage rate, it is desirable not only to optimize the temperature and time of the heat setting time, but also to perform the heat relaxation process at a temperature lower than the maximum temperature of the heat setting process.

  In the in-line coating method suitable for the present invention, the heat treatment in the heat setting of the film is mainly the heat treatment to the gas barrier layer (II). Therefore, by adopting the following heat treatment conditions as the heat treatment conditions in the heat setting, the heat treatment for the gas barrier layer (II) can be performed simultaneously with the stretching treatment. As a result, the total amount of heat received by the laminate during the manufacturing process can be reduced, so that thermal degradation is suppressed and the physical properties (such as mechanical properties) inherent to the laminate (especially plastic substrates) are effectively expressed. Can be made.

  Here, the heat treatment temperature for the gas barrier layer (II) can be set as appropriate depending on, for example, the presence or absence of an additive component and the content thereof, but is usually about 100 to 300 ° C., particularly 120 to 250 ° C. Preferably, it is more preferable that it is 140-240 degreeC, and it is most preferable that it is 160-220 degreeC among these. If the heat treatment temperature is too low, for example, the ester cross-linking reaction between polycarboxylic acids and polyalcohols cannot proceed sufficiently, so that ions with the metal compound of the plastic substrate (I) by subsequent hydrothermal treatment The cross-linking reaction cannot proceed sufficiently, and it may be difficult to obtain a laminate having sufficient gas barrier properties. On the other hand, if the heat treatment temperature is too high, the laminate may become brittle.

  The heat treatment time is usually 5 minutes or less, preferably 1 second to 5 minutes, more preferably 3 seconds to 2 minutes, and most preferably 5 seconds to 1 minute. If the heat treatment time is too short, the crosslinking reaction cannot proceed sufficiently, and it becomes difficult to obtain a laminate having gas barrier properties. On the other hand, if the heat treatment time is too long, productivity decreases.

  The gas barrier laminate of the present invention may be subjected to a surface treatment such as a corona discharge treatment as necessary as long as the effects of the present invention are not hindered.

  The gas barrier laminate of the present invention can be made into various laminated films by laminating a sealant or the like as necessary as long as the effects of the present invention are not hindered.

  Examples of the resin used as the sealant include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polyethylene / polypropylene copolymer, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic. Examples include acid / methacrylic acid copolymers, ethylene-acrylic acid / methacrylic acid ester copolymers, polyvinyl acetate resins, and the like, and polyethylene, polypropylene, and polyethylene / polypropylene copolymers that have high heat seal strength and high material strength. Polyolefin resins such as are preferred. These resins may be used alone, or may be used by being melt mixed with other resins. These resins may be subjected to a modification treatment such as acid modification.

  Examples of a method for forming a sealant layer on a gas barrier laminate include a method of laminating a film or sheet made of a sealant resin on a gas barrier laminate through an adhesive, a method of extrusion laminating a sealant resin on a gas barrier laminate, and the like. Can be mentioned. In the former method, the film or sheet made of the sealant resin may be in an unstretched state or may be in a stretched state at a low magnification, but it is preferably practically in an unstretched state.

  Although the thickness of a sealant layer is not specifically limited, Usually, it is preferable that it is 20-100 micrometers, and it is more preferable that it is especially 40-70 micrometers.

4). Use of Gas Barrier Laminate The laminate of the present invention can be used for various applications, and in particular, it can be suitably used as a packaging material taking advantage of its gas barrier properties. In particular, it can be used as a material (packaging bag) for constituting a bag. More specifically, it can be preferably used as a material for constituting a packaging bag for sealing the contents. Furthermore, like a retort pouch, it can be suitably used as a hermetic packaging bag for hot water treatment (for example, hermetic packaging bag immersed in hot water with the contents sealed). . Here, the conditions for the hot water treatment are not particularly limited, and can be set within a range in which a desired oxygen permeability (gas barrier property) can be exhibited. For example, the temperature of the hot water treatment (water temperature) is about 30 to 130 ° C. (under pressure in the case of 100 ° C. or higher), preferably 60 to 125 ° C., and most preferably 70 to 121 ° C. preferable. Therefore, for example, hydrothermal treatment at less than 100 ° C. (for example, 60 to 90 ° C.) in the atmosphere can be performed. Moreover, the time of a hot water process can be suitably set according to process temperature etc. in the range of 10 second-100 hours generally.

  The form of the bag body is not particularly limited. For example, a two-sided bag, a three-sided bag, a three-sided bag with a chuck, a jointed bag, a gusset bag, a bottom gusset bag, a stand bag, a stand chuck bag, a two-sided bag, a four-sided pillar flat bottom gusset bag. It can be applied to any of side seal bags, bottom seal bags and the like.

  Such packaging bags include, for example, foods and drinks, fruits, juices, drinking water, liquor, cooked foods, marine products, frozen foods, meat products, boiled foods, rice cakes, liquid soups, seasonings, etc. Various contents such as various foods and drinks, liquid detergents, cosmetics, and chemical products can be filled and packaged.

  The features of the present invention will be described more specifically with reference to the following examples and comparative examples. However, the scope of the present invention is not limited to the examples.

A. About the raw materials used The raw materials used in each Example and Comparative Example are as follows.

(1) Thermoplastic resin for constitution of plastic substrate (I) a) PA6: nylon 6 resin (“A1030BRF” manufactured by Unitika Ltd., relative viscosity 3.0 (25 ° C.))
(2) Metal compound for constituting plastic substrate (I) a) MgO: Magnesium oxide (“PUREMAG FNM-G” manufactured by Tateho Chemical Industries, average particle size 0.4 μm)
b) CaCO ₃ : calcium carbonate (“VIgot15” manufactured by Shiroishi Kogyo Co., Ltd., average particle size 0.5 μm)
c) ZnO: Zinc oxide (“FINEX-50” manufactured by Sakai Chemical Industry Co., Ltd., average particle size: 0.02 μm)
(3) Polycarboxylic acid component of gas barrier layer (II) forming coating solution a) EMA aqueous solution:
EMA (weight average molecular weight 60,000) and sodium hydroxide were added to water, dissolved by heating, and cooled to room temperature. 10 mol% of EMA carboxyl groups were neutralized with sodium hydroxide, solids EMA aqueous solution of 15% by mass. (Indicated as “EMA” in Table 1)
b) PAA aqueous solution:
10 mol% of the carboxyl group of polyacrylic acid prepared using polyacrylic acid ("A10H" manufactured by Toagosei Co., Ltd., weight average molecular weight 200,000, 25 wt% aqueous solution) and sodium hydroxide is sodium hydroxide An aqueous polyacrylic acid (PAA) solution having a solid content of 15% by mass, neutralized by the following. (Indicated as “PAA” in Table 1)
(4) Other resin components of coating liquid for forming gas barrier layer (II) a) PVA aqueous solution:
Polyvinyl alcohol ("Poval 105" manufactured by Kuraray Co., Ltd., saponification degree 98-99%, average polymerization degree about 500) was added to water, dissolved by heating, and then cooled to room temperature. Alcohol (PVA) aqueous solution. (Indicated as “PVA” in Table 1)
b) EVOH aqueous solution:
An ethylene-vinyl alcohol copolymer (EVOH) aqueous solution having a solid content of 10% by mass, in which an ethylene-vinyl alcohol copolymer (“Exeval AQ-4105” manufactured by Kuraray Co., Ltd.) is dissolved. (Indicated as “EVOH” in Table 1)
(5) Coating liquid for forming protective layer (III) a) Polyurethane resin 1
An aqueous polyurethane resin (“Takelac WS-4022” manufactured by Mitsui Chemicals, solid content: 30% by mass, Tg: 115 ° C.) was prepared to prepare a coating liquid having a solid content of 10% by mass. (Indicated as “WS-4022” in Table 1)
b) Polyurethane resin 2
An aqueous polyurethane resin (“Takelac WS-5984” manufactured by Mitsui Chemicals, solid content: 40 mass%, Tg: 70 ° C.) was prepared to prepare a coating liquid having a solid content of 10 mass%. (Indicated in Table 1 as “WS-5984”)
c) Polyurethane resin 3
An aqueous polyurethane resin (“Hydran AP-40F” manufactured by DIC, solid content 22.5 mass%, Tg: 55 ° C.) was prepared to prepare a coating liquid having a solid content of 10 mass%. (Indicated as “AP-40F” in Table 1)
d) Polyurethane resin 4
An aqueous polyurethane resin (“Hydran AP-201” manufactured by DIC, 23 mass% solid content, Tg: 10 ° C.) was prepared to prepare a coating liquid having a solid content of 10 mass%. (Indicated as “AP-201” in Table 1)
e) Polyester resin 1
An aqueous polyester resin (“Elitel KZA-1734” manufactured by Unitika Ltd., solid content: 30% by mass, Tg: 66 ° C.) was prepared to prepare a coating solution having a solid content of 10% by mass. (Indicated in Table 1 as “KZA-1734”)
f) PVA aqueous solution:
Solid content prepared by adding polyvinyl alcohol ("Poval 105" manufactured by Kuraray Co., Ltd., saponification degree of 98 to 99%, average polymerization degree of about 500, Tg: 85 ° C) to water, dissolving by heating and then cooling to room temperature. 10 mass% polyvinyl alcohol (PVA) aqueous solution. (Indicated as “PVA” in Table 1)
(6) Protective layer (III) Other resin components for forming coating liquid a) Melamine resin Methylol melamine resin (“Amidia APM” manufactured by DIC, solid content 80% by mass) (indicated as “APM” in Table 1) )
b) Isocyanate resin Polyisocyanate resin ("HW-100" manufactured by BASF, solid content: 100% by mass) (indicated as "HW-100" in Table 1)
c) Polycarboxylic acid aqueous solution EMA (weight average molecular weight 60,000) and sodium hydroxide were added to water, dissolved by heating, and then cooled to room temperature. A neutralized EMA aqueous solution having a solid content of 15% by mass. (Indicated as “EMA” in Table 1)

B. About Examples and Comparative Examples
Example 1
Nylon 6 resin and master chip were mixed so that the content of magnesium oxide was 0.1% by mass. This mixture was charged into an extruder and melted in a 270 ° C. cylinder. The melt was extruded into a sheet form from a T-die orifice, brought into close contact with a rotating drum cooled to 10 ° C., and rapidly cooled to obtain an unstretched film having a thickness of 150 μm. The obtained unstretched film was sent to a 50 ° C. hot water tank and subjected to a water immersion treatment for 2 minutes.
Next, an EMA aqueous solution and a PVA aqueous solution are mixed so that the mass ratio (solid content) of EMA and PVA is 70/30, and a coating solution for forming a gas barrier layer (II) having a solid content of 10% by mass is obtained. Obtained. This coating solution was applied to one side of an unstretched film that had been subjected to a water immersion treatment by an air knife coating method, and was subjected to a drying treatment for 30 seconds using an infrared irradiator at a temperature of 110 ° C.
In the unstretched film coated with the gas barrier layer (II) forming coating solution, the protective layer (III) forming coating solution is applied to the opposite surface to which the gas barrier layer (II) forming coating solution is applied. A coating liquid made of polyurethane resin 1 was applied by an air knife coating method, and dried for 30 seconds using an infrared irradiator at a temperature of 110 ° C.
The ends of the film in which the coating liquid for forming the gas barrier layer (II) and the coating liquid for forming the protective layer (III) are laminated on both surfaces of the unstretched film are held by the clips of the tenter simultaneous biaxial stretching machine, Each film was stretched 3.3 times in MD and TD at 180 ° C. Thereafter, the relaxation rate of TD was set to 5%, heat treatment was performed at 210 ° C. for 4 seconds, and the mixture was gradually cooled to room temperature. In this way, a laminate was obtained in which a gas barrier layer (II) having a thickness of 0.3 μm and a protective layer (III) having a thickness of 0.5 μm were formed on a plastic substrate (I) having a thickness of 15 μm.

Examples 2 to 16 and Comparative Examples 1 to 6
Examples described in Table 1 except that the type and content of the metal compound in the thermoplastic composition resin film (I), the composition of the gas barrier layer (II) and the protective layer (III) and the coating thickness were changed. 1 to obtain a laminate.

Test example 1
About the sample (laminated body) obtained by each Example and the comparative example, it measured according to each measuring method about the following physical properties. The results are shown in Table 1.

(1) Thickness of each layer The obtained gas barrier laminate is allowed to stand for 2 hours or more in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH, and then a cross section of the film is observed with a scanning electron microscope (SEM). The thickness of was measured.

(2) Oxygen Permeability The obtained gas barrier laminate was hydrothermally treated under conditions of 80 ° C. × 30 minutes or 120 ° C. × 30 minutes, and after adhering water droplets were wiped off, the temperature was 23 ° C. and the relative humidity was 90% RH. Then, the oxygen transmission rate was measured in an atmosphere of a temperature of 20 ° C. and a relative humidity of 90% using an oxygen barrier measuring device (OX-TRAN 2/20) manufactured by Mocon. The unit is ml / (m ² · day · MPa).

(3) Measurement of metal content and reduction in film After heating the gas barrier laminate before and after hydrothermal treatment at 120 ° C. for 30 minutes in a mixed acid of nitric acid and sulfuric acid, the insoluble portion is made of perchloric acid and hydrofluoric acid. Heat in mixed acid to dissolve completely. The metal concentration in the solution was measured with a plasma atomic emission spectrometer (iCAP6500Duo) manufactured by Thermo Fisher Scientific, and the metal content in the film was calculated. The reduction rate of the metal content was calculated based on the following formula. did.
Metal content reduction rate (%) = (MA-MB) / MA × 100
MA: Metal content in film before hydrothermal treatment MB: Metal content in film after hydrothermal treatment at 120 ° C. for 30 minutes

As is clear from the results in Table 1, in Examples 1 to 16, a gas barrier layer containing a polycarboxylic acid on one surface of a plastic substrate (I) containing 0.1 to 20% by mass of a metal compound ( II) is laminated, and the protective layer (III) containing a resin component having a glass transition temperature of 60 ° C. or higher is laminated on the other surface, so that even in hot water treatment at a relatively low temperature and in a short time It can be seen that good gas barrier properties can be obtained. In particular, in Examples 3 and 4 and the like, it can be seen that a high gas barrier property of ^{2 to} 10 ml / (m ² · day · MPa) can be exhibited even after the hot water treatment at 80 ° C. for 30 minutes.

  On the other hand, Comparative Example 1 does not have a protective layer (III), so that the amount of metal outflow during hydrothermal treatment is large, and the oxygen permeability is high in hydrothermal treatment at a relatively low temperature and in a short time. It can be seen that high gas barrier properties cannot be obtained. In Comparative Examples 2 and 3, since the glass transition temperature of the protective layer (III) is lower than the range specified in the present invention, the amount of metal flowing out by the hydrothermal treatment is large, and after the hydrothermal treatment at a relatively low temperature and a short time. The oxygen permeability is high. In Comparative Example 4, since the amount of the metal compound contained in the plastic substrate (I) is less than the range defined in the present invention, the oxygen permeability after the hot water treatment is high. Since the gas barrier layer (II) does not contain polycarboxylic acid in Comparative Example 5, it can be confirmed that the oxygen permeability after the hot water treatment is high. In Comparative Example 6, since the gas barrier layer (II) was not formed, the obtained laminate had high oxygen permeability after the hot water treatment.

Claims (9)

A laminate comprising at least a protective layer (III), a plastic substrate (I) and a gas barrier layer (II) in order,
(1) The plastic substrate (I) contains a resin component and a metal compound, and the content of the metal compound is 0.1 to 20% by mass,
(2) The gas barrier layer (II) contains polycarboxylic acid or an anhydride thereof and is laminated on one surface of the plastic substrate (I).
(3) The protective layer (III) contains a resin component having a glass transition temperature of 60 ° C. or higher, and is laminated on the other surface of the plastic substrate (I).
A gas barrier laminate characterized by that. The gas barrier laminate according to claim 1, wherein the plastic substrate (I) is a polyamide-based film. The gas barrier laminate according to claim 1 or 2, wherein the gas barrier layer (II) further contains a polyalcohol. The gas barrier laminate according to any one of claims 1 to 3, wherein the protective layer (III) contains a polyalcohol. The gas barrier laminate according to any one of claims 1 to 4, wherein the thickness of the protective layer (III) is 1 µm or less. In an oxygen permeability under an atmosphere of a temperature of 20 ° C. and a relative humidity of 90%, the oxygen permeability after hydrothermal treatment at 80 ° C. × 30 minutes is 100 ml / (m ² · day · MPa) or less, and the temperature is 120 ° C. × The gas barrier laminate according to any one of claims 1 to 5, wherein the oxygen permeability after 30 minutes of hot water treatment is 100 ml / (m ² · day · MPa) or less. The gas barrier laminate according to any one of claims 1 to 5, which is used for hot water treatment with hot water at a temperature of 30 to 130 ° C. The packaging material containing the gas barrier laminated body in any one of Claims 1-7. The packaging material according to claim 8, which is used for sealing the contents.