Gas barrier film

Abstract

To provide a gas barrier film high in resistance to hot water treatment and having a suppressed environmental load.SOLUTION: A gas barrier film 100 includes a substrate 10 mainly composed of polypropylene and an oxygen barrier film 15 formed on a side of a first surface 10a of the substrate. In the infrared spectroscopic measurement of the first surface, a ratio of peak intensity I1 present at 1360 to 1390 cm-1 to peak intensity I2 present at 1440 to 1480 cm-1 satisfies a formula (1): I1 / I2≤1.55. On the first surface, microparticles made of materials other than polypropylene protrude, with the number of microparticles being no more than 100 in a region of 257 μm×259 μm (area 0.067 mm2), and average protrusion height of the microparticles is 2.5 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas barrier film. [Background technology]

[0002] Packaging materials used for packaging foods, pharmaceuticals, etc. are required to have gas barrier properties, i.e., the ability to prevent the intrusion of gases (water vapor, oxygen, etc.) that denature the contents, in order to prevent deterioration and spoilage of the contents and maintain their functionality and quality. For this reason, film materials with gas barrier properties (gas barrier films) are used for these packaging materials.

[0003] Known gas barrier films include those in which a gas barrier layer made of a material having gas barrier properties is provided on the surface of a resin substrate. Examples of gas barrier layers include metal foils, metal vapor deposition films, and films formed by wet coating. Examples of such films that exhibit oxygen barrier properties include resin films formed from coating agents containing water-soluble polymers and resins such as polyvinylidene chloride, and inorganic layered mineral composite resin films formed from coating agents containing water-soluble polymers and inorganic layered minerals (see, for example, Patent Document 1).

[0004] Further proposed gas barrier layers include a vapor-deposited thin film layer made of an inorganic oxide (see, for example, Patent Document 2), a gas barrier layer in which a gas barrier composite coating containing an aqueous polymer, an inorganic layered compound, and a metal alkoxide is laminated in this order (see, for example, Patent Document 3), and a gas barrier layer containing a polyvalent metal salt of a carboxylic acid, which is a reaction product between a carboxy group of a polycarboxylic acid polymer and a polyvalent metal compound (see, for example, Patent Document 4).

[0005] These gas barrier films have transparency and oxygen blocking properties. As the base film, those made of polyethylene terephthalate (PET) are often used. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6176239 [Patent Document 2] Japanese Unexamined Patent Publication No. 60-49934 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-254994 [Patent Document 4] Patent No. 4373797 Summary of the Invention [Problem to be solved by the invention]

[0007] However, gas barrier films in which a coating is formed on the surface of a resin substrate by a wet coating method, a vapor deposition method, or a sputtering method sometimes have unstable oxygen barrier properties depending on the production lot. Specifically, the oxygen barrier properties of the gas barrier film are sometimes inferior to the inherent oxygen barrier properties, i.e., the oxygen barrier properties expected from the material constituting the coating and the thickness of the coating. In particular, such problems tend to occur more easily when the coating thickness is thin.

[0008] Furthermore, in recent years, there has been an increasing demand for gas barrier films that use base films made of polypropylene (PP) or polyethylene (PE) in order to reduce the burden on the environment. However, the inventors' investigations have revealed that gas barrier films that simply have a barrier layer formed on a PP base film do not actually have sufficient resistance to hot water treatments such as boiling and retorting.

[0009] In light of the above circumstances, an object of the present invention is to provide a gas barrier film that can fully exhibit its inherent oxygen barrier properties even when the thickness of the coating for imparting oxygen barrier properties is thin, that has high resistance to hot water treatment, and that also reduces the environmental impact. [Means for solving the problem]

[0010] The present invention provides a gas barrier film comprising a substrate containing polypropylene as a main component and an oxygen barrier coating on a first surface of the substrate, wherein infrared spectroscopy of the first surface shows an oxygen barrier property of 1360 to 1390 cm -1 The peak intensity I1 present at 1440-1480 cm -1 When the ratio of the peak intensity I2 present in the peak intensity I3 to the peak intensity I4 present in the peak intensity I5 satisfies the following formula (1), a gas barrier film can be provided which has sufficient hot water resistance with an adhesion strength of 1.0 N / 15 mm or more after hot water treatment and which also has a reduced environmental impact. I1 / I2≦1.65 …(1)

[0011] Furthermore, if the number of microparticles added to prevent blocking of the resin substrate is 100 or less per area of ​​250 μm on a side, and the average protrusion height is 2.5 μm or less, defects in the oxygen barrier coating that serve as paths for gas permeation are minimized, making it possible to provide a gas barrier film with high oxygen barrier properties.

[0012] The present invention is based on the above findings and has the following aspects. [1] A base material mainly composed of polypropylene, an oxygen barrier coating (excluding those containing an inorganic layered compound) on the first surface side of the substrate; a base layer, or both a base layer and an inorganic oxide layer, is provided between the resin substrate and the oxygen barrier coating; In infrared spectroscopy of the first surface, -1 The peak intensity I1 present at 1440-1480 cm -1 The ratio of the peak intensity I2 present in the I1 / I2≦1.55 …(1) the first surface has protruding particles made of a material other than polypropylene; The number of particles is determined by the number of particles in an area of ​​257 μm × 259 μm (area 0.067 mm 2 ) or less, A gas barrier film, wherein the average protrusion height of the fine particles is 2.5 μm or less. [2] The substrate is The resin layer has two or more resin layers including a base layer and a surface layer that constitutes the first surface, The value of the formula (1) in infrared spectroscopy measurement of the resin layer on the second surface opposite to the first surface is The gas barrier film according to [1], wherein the value of the formula (1) on the first surface is larger than that on the first surface. [3] The gas barrier film according to [1] or [2], wherein the thickness of the underlayer is 0.01 to 1 μm. [4] The underlayer contains an organic polymer as a main component, The gas barrier film according to any one of [1] to [3], wherein the organic polymer comprises at least one of a polyacrylic resin, a polyol resin, a polyurethane resin, a polyamide resin, or a reaction product of these organic polymers. [5] The gas barrier film according to any one of [1] to [4], wherein the inorganic oxide layer has a thickness of 1 to 200 nm. [6] The gas barrier film according to any one of [1] to [5], wherein the inorganic oxide layer is aluminum oxide or silicon oxide. [7] The gas barrier film according to any one of [1] to [6], wherein the oxygen barrier coating has a thickness of 0.05 to 1 μm. [8] The gas barrier film according to any one of [1] to [7], wherein the oxygen barrier coating is a coating containing at least one of a metal alkoxide, a hydrolyzate thereof, or a reaction product thereof, and a water-soluble polymer. [9] The gas barrier film according to [8], wherein the oxygen barrier coating further contains at least one of a silane coupling agent, a hydrolyzate thereof, or a reaction product thereof.

[10] The gas barrier film according to any one of [1] to [7], wherein the oxygen barrier coating contains a polyvalent metal salt of a carboxylic acid, which is a reaction product between a carboxy group of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B).

[11] The gas barrier film according to any one of [1] to

[10] , wherein the substrate further comprises a heat-sealable sealant layer, and the sealant layer is bonded to the oxygen barrier coating by an adhesive layer.

[12] After hot water treatment at 120 ° C for 30 minutes, Oxygen permeability is 5.0cc / m 2 ·day or less, The gas barrier film according to any one of [1] to

[11] , wherein the peel strength between the substrate and the sealant layer is 1.0 N / 15 mm or more. [Effects of the Invention]

[0013] According to the present invention, a gas barrier film having high resistance to hot water treatment and reduced environmental impact can be provided. Furthermore, even if the thickness of the coating for imparting oxygen barrier properties is thin, the inherent oxygen barrier properties can be fully exhibited, and the film has excellent oxygen barrier properties. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view of a gas barrier film according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The gas barrier film of the present invention will be described with reference to an embodiment.

[0016] Fig. 1 is a schematic cross-sectional view of a gas barrier film 100 according to an embodiment of the present invention. For the sake of convenience, the dimensional ratios in Fig. 1 are different from the actual ratios.

[0017] The gas barrier film 100 comprises a resin substrate 10, an underlayer 13, an inorganic oxide layer 14, and an oxygen barrier coating 15. The inorganic oxide layer 14 may be omitted.

[0018] The substrate 10 has two or more resin layers, and includes at least a surface layer 11 and a base layer 12 , and the surface layer 11 has fine particles 16 .

[0019] The underlayer 13 is located in contact with the first surface 10a of the resin substrate 10, and the inorganic oxide layer 14 or the oxygen barrier film 15 is located in contact with the opposite surface.

[0020] The gas barrier film 100 has a sealant layer 18 , which is positioned in contact with an adhesive layer 17 , and the adhesive layer 17 is positioned in contact with an oxygen barrier coating 15 .

[0021] The substrate 10 has two or more resin layers whose main component is polypropylene. The substrate of this embodiment has two resin layers: a base layer 12 and a surface layer 11 laminated on the base layer 12.

[0022] The substrate 10 having two or more resin layers can be formed, for example, by coextrusion. The total thickness of the substrate 10, which is the sum of the thicknesses of the base layer 12 and the surface layer 11, can be, for example, 3 to 200 μm, and preferably 15 to 60 μm.

[0023] The resin used to make each layer of the substrate 10 is primarily polypropylene, due to its ease of availability, water vapor barrier properties, and environmental impact. Polypropylene may be a homopolymer, random copolymer, block copolymer, or terpolymer. A homopolymer is a polypropylene composed solely of propylene. A random copolymer is a polypropylene in which the main monomer, propylene, is randomly copolymerized with a different comonomer to form a homogeneous phase. A block copolymer is a polypropylene in which the main monomer, propylene, and the comonomer are copolymerized in a block or rubber-like manner to form a heterogeneous phase. A terpolymer is a polypropylene in which the main monomer, propylene, is copolymerized with two different comonomers. These polyolefin resins may be used alone or in a blend of two or more. The base layer 12 is preferably made of a homopolymer, random copolymer, or block copolymer. The surface layer 11 is preferably made of a random copolymer, block copolymer, or terpolymer.

[0024] The base layer 12 may contain additives. The additives can be appropriately selected from various known additives. Examples of additives include antiblocking agents (AB agents), heat stabilizers, weather stabilizers, UV absorbers, lubricants, slip agents, nucleating agents, antistatic agents, antifogging agents, pigments, and dyes. Any one of these additives may be used alone, or two or more may be used in combination. Of the above, lubricants and slip agents are preferred from the viewpoint of processability. The content of additives in the base layer 12 can be appropriately adjusted within a range that does not impair the effects of the present invention. The base layer 12 typically does not contain an AB agent.

[0025] The base layer 12 may have a single layer structure or a multi-layer structure. The thickness of the base layer 12 may be, for example, 3 to 200 μm, or 6 to 30 μm.

[0026] The raw material of the surface layer 11 is preferably any one of a random copolymer, a block copolymer, and a terpolymer.

[0027] The surface layer 11 contains fine particles, typically an AB agent. If the number of fine particles is 100 or less per 250 μm-side region and the average protrusion height is 5 μm or less, the occurrence of defects that could become paths for gas permeation can be suppressed during the formation of the oxygen barrier coating 15, and excellent oxygen barrier properties can be achieved.

[0028] The surface layer 11 may contain additives other than the AB agent. The additives can be appropriately selected from various known additives. Examples of additives include heat stabilizers, weather stabilizers, UV absorbers, lubricants, slipping agents, nucleating agents, antistatic agents, anti-fogging agents, pigments, and dyes. Any one of these additives may be used alone, or two or more may be used in combination. Of the above, lubricants and slipping agents are preferred from the viewpoint of processability. The content of the additives in the surface layer 11 can be appropriately adjusted within a range that does not impair the effects of the present invention.

[0029] The thickness of the surface layer 11 may be, for example, 0.1 to 10 μm, or may be 0.5 to 5.0 μm.

[0030] The microparticles 16 are typically AB agents, and are solid particles, and examples thereof include organic particles and inorganic particles. Examples of organic particles include polymethyl methacrylate particles, polystyrene particles, and polyamide particles. These organic particles are obtained, for example, by emulsion polymerization or suspension polymerization. Examples of inorganic particles include silica particles, zeolite, talc, kaolinite, and feldspar. These AB agents may be used alone or in combination of two or more. As the microparticles 16, polymethyl methacrylate particles are preferred among organic particles, and silica particles are preferred among inorganic particles.

[0031] The average particle size of the fine particles 16 is preferably 0.1 μm or more and 5 μm or less, taking into consideration the appearance of the first surface 10a, the transparency of the substrate 10, the possibility of the fine particles 16 falling off, and anti-blocking performance.

[0032] The amount of the fine particles 16 added to the surface layer 11 is, for example, 0.1 to 0.4 mass % with respect to the total mass of the surface layer 11. The amount of the fine particles 16 added to the surface layer 11 is specifically calculated by the following formula. Amount of fine particles added [mass%] = {(i) / 100} × {(ii) / 100} × 100 In the formula, (i) represents the concentration (mass%) of fine particles in masterbatch resin chips obtained by adding fine particles to a resin, stirring the mixture, feeding the mixture into an extruder, kneading the mixture, and melt-extruding the mixture into pellets; (ii) indicates the concentration (mass %) of masterbatch resin chips containing fine particles relative to the total mass of resin pellets constituting the surface layer 11 when the masterbatch resin chips containing fine particles are blended with a resin not containing fine particles.

[0033] The fine particles 16 may be contained on the second surface 10b of the substrate 10, and are preferably contained therein in consideration of anti-blocking performance.

[0034] The resin substrate 10 is preferably a coextruded film in which the layers including the surface layer 11 and the base layer 12 are laminated by coextrusion. The resin substrate 10 may be a stretched film or an unstretched film.

[0035] The resin substrate 10 preferably has a biaxially oriented polypropylene film. Biaxially oriented polypropylene film has particularly excellent water vapor barrier properties, so by including a biaxially oriented polypropylene film, the gas barrier film 100 has excellent water vapor barrier properties. The biaxially oriented polypropylene film may be at least one of a homopolymer, a random copolymer, a block copolymer, etc. processed into a film shape. The biaxially oriented polypropylene film is preferably a coextruded film.

[0036] The thickness of the resin substrate 10 can be adjusted depending on the application, desired properties, etc., and is not particularly limited, but may be, for example, 3 to 200 μm, or may further be 6 to 30 μm. The thickness of the resin substrate 10 is the thickness of a portion where no protrusions resulting from the fine particles 16 exist.

[0037] The surfaces (first surface 10a, second surface 10b) of the resin substrate 10 may be subjected to at least one treatment selected from the group consisting of chemical treatment, solvent treatment, corona treatment, plasma treatment, and ozone treatment.

[0038] (base layer) The underlayer 13 is provided between the resin substrate 10 and the inorganic oxide layer 14 or the oxygen barrier film 15 .

[0039] The underlayer 13 is a layer containing an organic polymer as a main component and is sometimes called a primer layer. The provision of the underlayer 13 can improve the film-forming properties and adhesion strength of the inorganic oxide layer 14 or the oxygen barrier coating 15.

[0040] The content of the organic polymer in the underlayer 13 may be, for example, 70% by mass or more, or 80% by mass or more. Examples of the organic polymer include polyacrylic resin, polyester resin, polycarbonate resin, polyurethane resin, polyamide resin, polyolefin resin, polyimide resin, melamine resin, and phenolic resin. In consideration of the hot water resistance of the adhesive strength between the resin substrate 10 and the inorganic oxide layer 14 or the oxygen barrier coating 15, the underlayer 13 preferably contains at least one of a polyacrylic resin, a polyol resin, a polyurethane resin, a polyamide resin, or a reaction product of these organic polymers. The underlayer 13 may also contain a silane coupling agent, an organic titanate, or a modified silicone oil.

[0041] More preferred examples of the organic polymer include organic polymers having a urethane bond formed by the reaction of a polyol having two or more hydroxyl groups at the polymer terminal with an isocyanate compound, and / or organic polymers containing a reaction product of a polyol having two or more hydroxyl groups at the polymer terminal with an organic silane compound such as a silane coupling agent or a hydrolyzate thereof.

[0042] Examples of polyols include at least one selected from acrylic polyol, polyvinyl acetal, polystyrene polyol, and polyurethane polyol. The acrylic polyol may be obtained by polymerizing an acrylic acid derivative monomer, or may be obtained by copolymerizing an acrylic acid derivative monomer with another monomer. Examples of the acrylic acid derivative monomer include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of the monomer copolymerized with the acrylic acid derivative monomer include styrene.

[0043] The isocyanate compound reacts with the polyol to form a urethane bond, thereby enhancing the adhesion between the resin substrate 10 and the inorganic oxide layer 14 or the oxygen barrier coating 15. In other words, the isocyanate compound functions as a crosslinking agent or curing agent. Examples of isocyanate compounds include aromatic monomers such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic monomers such as xylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), and isophorone diisocyanate (IPDI), as well as polymers and derivatives thereof. The above-mentioned isocyanate compounds may be used alone or in combination.

[0044] Examples of silane coupling agents include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. The organic silane compound may be a hydrolyzate of these silane coupling agents. The organic silane compound may contain one of the above-mentioned silane coupling agents and their hydrolyzates, or two or more of them in combination.

[0045] The underlayer 13 can be formed by preparing a mixed solution by blending the above-mentioned components in an organic solvent in any ratio, and using the prepared mixed solution on the first surface 10a of the resin substrate 10. The mixed solution may contain, for example, a curing accelerator such as a tertiary amine, an imidazole derivative, a metal salt compound of a carboxylic acid, a quaternary ammonium salt, or a quaternary phosphonium salt; an antioxidant such as a phenol-based, sulfur-based, or phosphite-based antioxidant; a leveling agent; a flow adjuster; a catalyst; a crosslinking reaction accelerator; a filler; etc.

[0046] The mixed liquid can be coated onto the resin substrate 10 using a known printing method such as offset printing, gravure printing, or silk screen printing, or a known application method such as roll coating, knife edge coating, or gravure coating. After coating, the mixture can be heated to, for example, 50 to 200°C, and dried and / or cured to form the underlayer 13.

[0047] The thickness of the underlayer 13 is not particularly limited and may be, for example, 0.005 to 5 μm. The thickness may be adjusted depending on the application or desired properties. The thickness of the underlayer 13 is preferably 0.01 to 1 μm, and more preferably 0.01 to 0.5 μm. If the thickness of the underlayer 13 is 0.01 μm or more, sufficient adhesion strength between the resin substrate 10 and the inorganic oxide layer 14 or the oxygen barrier film 15 is obtained, and the oxygen barrier properties are also good. If the thickness of the underlayer 27 is 1 μm or less, it is easy to form a uniform coated surface, and drying load and production costs can be reduced.

[0048] (inorganic oxide layer) Examples of materials for the inorganic oxide layer 14 include aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, tin oxide, zinc oxide, and indium oxide. Aluminum oxide or silicon oxide is particularly preferred because of its excellent productivity and excellent oxygen and water vapor barrier properties in heat and moist heat resistance. The inorganic oxide layer 14 may contain one of these materials alone or a combination of two or more. The thickness of the inorganic oxide layer 14 is preferably 1 to 200 nm. A thickness of 1 nm or more provides excellent oxygen and water vapor barrier properties. A thickness of 200 nm or less reduces manufacturing costs and reduces cracking due to external forces such as bending or pulling, thereby suppressing deterioration of barrier properties. The inorganic oxide layer 14 can be formed by known film formation methods, such as vacuum deposition, sputtering, ion plating, or plasma vapor deposition (CVD).

[0049] (Oxygen barrier film) The oxygen barrier film 15 may be a known oxygen barrier film formed by a wet coating method. The oxygen barrier film 15 is obtained by forming a coating film made of a coating agent on the underlayer 13 or the inorganic oxide layer 14 by a wet coating method, and then drying the coating film. The coating film is a wet film, and the film is a dry film.

[0050] The oxygen barrier film 15 is preferably a film containing a water-soluble polymer and at least one of a metal alkoxide, its hydrolysate, or its reaction product (organic-inorganic composite film), and more preferably a film further containing at least one of a silane coupling agent and its hydrolysate.

[0051] Examples of metal alkoxides and their hydrolysates contained in the organic-inorganic composite film include those represented by the general formula M(OR), such as tetraethoxysilane [Si(OC2H5)4] and triisopropoxyaluminum [Al(OC3H7)3]. n and hydrolysates thereof. One of these may be contained alone, or two or more may be contained in combination.

[0052] The total content of at least one of the metal alkoxide, its hydrolysate, and / or its reaction product in the organic-inorganic composite membrane is, for example, 40 to 70 mass%. From the viewpoint of further reducing oxygen permeability, the lower limit of the total content of at least one of the metal alkoxide, its hydrolysate, and / or its reaction product in the organic-inorganic composite membrane may be 50 mass%. From the same viewpoint, the upper limit of the total content of at least one of the metal alkoxide, its hydrolysate, and / or its reaction product in the organic-inorganic composite membrane may be 65 mass%.

[0053] The water-soluble polymer contained in the organic-inorganic composite film is not particularly limited, and examples thereof include polyvinyl alcohol-based polymers, polysaccharides such as starch, methyl cellulose, and carboxymethyl cellulose, and acrylic polyol-based polymers. From the viewpoint of further improving the oxygen gas barrier property, the water-soluble polymer preferably contains a polyvinyl alcohol-based polymer. The number-average molecular weight of the water-soluble polymer is, for example, 40,000 to 180,000.

[0054] A water-soluble polymer such as polyvinyl alcohol can be obtained by, for example, saponifying (including partial saponification) polyvinyl acetate. This water-soluble polymer may have several tens of percent or only a few percent of acetate groups remaining.

[0055] The content of the water-soluble polymer in the organic-inorganic composite membrane is, for example, 15 to 50 mass%. The lower limit of the content of the water-soluble polymer in the organic-inorganic composite membrane may be 20 mass% from the viewpoint of further reducing oxygen permeability. The upper limit of the content of the water-soluble polymer in the organic-inorganic composite membrane may be 45 mass% from the viewpoint of further reducing oxygen permeability.

[0056] Silane coupling agents and their hydrolysates contained in the organic-inorganic composite film include silane coupling agents having organic functional groups. Examples of such silane coupling agents and their hydrolysates include ethyltrimethoxysilane, vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and their hydrolysates. One of these may be contained alone, or two or more may be contained in combination.

[0057] At least one of the silane coupling agent and its hydrolysate preferably has an epoxy group as the organic functional group. Examples of silane coupling agents having an epoxy group include γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The silane coupling agent having an epoxy group and its hydrolysate may have an organic functional group other than the epoxy group, such as a vinyl group, an amino group, a methacryl group, or a ureyl group.

[0058] The silane coupling agent having an organic functional group and its hydrolysate can further improve the oxygen barrier properties of the oxygen barrier coating 15 and the adhesion to the underlayer 13 or the inorganic oxide layer 14 through the interaction between the organic functional group and the hydroxyl group of the water-soluble polymer. In particular, the epoxy groups of the silane coupling agent and its hydrolysate can interact with the hydroxyl groups of polyvinyl alcohol to form an oxygen barrier coating 15 that is particularly excellent in oxygen barrier properties and adhesion to the underlayer 13 or the inorganic oxide layer 14.

[0059] The total content of at least one of the silane coupling agent and its hydrolysate and / or reaction product thereof in the organic-inorganic composite film is, for example, 1 to 15 mass%. From the viewpoint of further reducing oxygen permeability, the lower limit of the total content of at least one of the silane coupling agent and its hydrolysate and / or reaction product thereof in the organic-inorganic composite film may be 2 mass%. From the same viewpoint, the upper limit of the total content of at least one of the silane coupling agent and its hydrolysate and / or reaction product thereof in the organic-inorganic composite film may be 12 mass%.

[0060] The organic-inorganic composite film may contain a crystalline inorganic layered compound having a layered structure. Examples of the inorganic layered compound include clay minerals such as kaolinite, smectite, and mica. One of these may be used alone, or two or more may be used in combination. The particle size of the inorganic layered compound is, for example, 0.1 to 10 μm. The aspect ratio of the inorganic layered compound is, for example, 50 to 5,000.

[0061] As the inorganic layered compound, a smectite clay mineral is preferred because it can form a film with excellent oxygen barrier properties and adhesive strength by allowing a water-soluble polymer to penetrate between the layers of the layered structure (intercalation).Specific examples of smectite clay minerals include montmorillonite, hectorite, saponite, and water-swellable synthetic mica.

[0062] Another preferred example of the oxygen barrier film 15 is a film containing a polyvalent metal salt of carboxylic acid, which is a reaction product between a carboxy group of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B) (a polyvalent metal salt of polycarboxylic acid film). In this case, the film may be a polyvalent metal salt of polycarboxylic acid film formed by applying a coating agent containing a mixture of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B) and drying the mixture under heat, or a polyvalent metal salt of polycarboxylic acid film formed by applying a coating agent containing a polycarboxylic acid polymer (A) as the main component and drying it to form a film A, applying a coating agent containing a polyvalent metal compound (B) as the main component thereon, and drying the coating agent to form a film B, and then allowing a crosslinking reaction between the A and B layers.

[0063] [Polycarboxylic acid polymer (A)] A polycarboxylic acid polymer is a polymer having two or more carboxy groups in its molecule. Examples of polycarboxylic acid polymers include (co)polymers of ethylenically unsaturated carboxylic acids; copolymers of ethylenically unsaturated carboxylic acids with other ethylenically unsaturated monomers; and acidic polysaccharides having a carboxyl group in their molecules, such as alginic acid, carboxymethyl cellulose, and pectin. Examples of the ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of ethylenically unsaturated monomers copolymerizable with the ethylenically unsaturated carboxylic acids include saturated carboxylic acid vinyl esters such as ethylene, propylene, and vinyl acetate, alkyl acrylates, alkyl methacrylates, alkyl itaconates, vinyl chloride, vinylidene chloride, styrene, acrylamide, and acrylonitrile. These polycarboxylic acid polymers may be used alone or in combination of two or more.

[0064] Among the above, from the viewpoint of the gas barrier properties of the resulting gas barrier film, preferred components are polymers containing a structural unit derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, itaconic acid, fumaric acid, and crotonic acid, and particularly preferred are polymers containing a structural unit derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, and itaconic acid.

[0065] In the polymer, the proportion of structural units derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, and itaconic acid is preferably 80 mol% or more, and more preferably 90 mol% or more (where the total of all structural units constituting the polymer is 100 mol%). The polymer may be a homopolymer or a copolymer. When the polymer is a copolymer containing structural units other than the above structural units, examples of the other structural units include structural units derived from the above-mentioned ethylenically unsaturated monomers copolymerizable with the ethylenically unsaturated carboxylic acid.

[0066] The number-average molecular weight of the polycarboxylic acid polymer is preferably in the range of 2,000 to 10,000,000, and more preferably 5,000 to 1,000,000. If the number-average molecular weight is less than 2,000, the resulting gas barrier film will not achieve sufficient water resistance, and moisture may deteriorate the gas barrier properties and transparency, or whitening may occur. On the other hand, if the number-average molecular weight exceeds 10,000,000, the viscosity of the coating agent used to form the oxygen barrier film 15 may increase, impairing coatability. The number-average molecular weight is the polystyrene-equivalent number-average molecular weight determined by gel permeation chromatography (GPC).

[0067] When a coating agent containing a polycarboxylic acid polymer (A) as a main component is applied and dried to form a coating A, and then the coating B is formed, some of the carboxy groups of the polycarboxylic acid polymer may be neutralized in advance with a basic compound. By neutralizing some of the carboxy groups of the polycarboxylic acid polymer in advance, the water resistance and heat resistance of the coating A can be further improved. The basic compound is preferably at least one basic compound selected from the group consisting of polyvalent metal compounds, monovalent metal compounds, and ammonia. As the polyvalent metal compound, compounds exemplified in the description of the polyvalent metal compound (B) below can be used. Examples of monovalent metal compounds include sodium hydroxide and potassium hydroxide.

[0068] Various additives can be added to the coating agent containing the polycarboxylic acid polymer (A) as the main component, and examples of such additives include crosslinking agents, curing agents, leveling agents, antifoaming agents, antiblocking agents, antistatic agents, dispersants, surfactants, softeners, stabilizers, film-forming agents, and thickeners, provided that the barrier performance is not impaired.

[0069] The solvent used in the coating agent containing polycarboxylic acid polymer (A) as the main component is preferably an aqueous medium. Examples of the aqueous medium include water, water-soluble or hydrophilic organic solvents, and mixtures thereof. The aqueous medium usually contains water or water as the main component. The water content in the aqueous medium is preferably 70% by mass or more, more preferably 80% by mass or more. Examples of the water-soluble or hydrophilic organic solvent include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran, cellosolves, carbitols, and nitriles such as acetonitrile.

[0070] [Polyvalent metal compounds (B)] The polyvalent metal compound is not particularly limited as long as it is a compound that reacts with the carboxyl groups of the polycarboxylic acid polymer to form a polyvalent metal salt of polycarboxylic acid, and examples thereof include zinc oxide particles, magnesium oxide particles, magnesium methoxide, copper oxide, calcium carbonate, etc. These may be used alone or in combination. Zinc oxide is preferred from the viewpoint of the oxygen barrier properties of the oxygen barrier coating.

[0071] Zinc oxide is an inorganic material capable of absorbing ultraviolet light. The average particle size of the zinc oxide particles is not particularly limited, but from the viewpoints of gas barrier properties, transparency, and coating suitability, the average particle size is preferably 5 μm or less, more preferably 1 μm or less, and particularly preferably 0.1 μm or less.

[0072] When a coating agent containing a polyvalent metal compound (B) as a main component is applied and dried to form a B film, various additives may be added in addition to zinc oxide particles as needed, provided that the effects of the present invention are not impaired. Such additives may include a resin soluble or dispersible in the solvent used in the coating agent, a dispersant soluble or dispersible in the solvent, a surfactant, a softener, a stabilizer, a film-forming agent, a thickener, etc.

[0073] Among the above, it is preferable to contain a resin that is soluble or dispersible in the solvent used in the coating agent. This improves the coatability and film-forming properties of the coating agent. Examples of such resins include alkyd resins, melamine resins, acrylic resins, urethane resins, polyester resins, phenolic resins, amino resins, fluororesins, epoxy resins, and isocyanate resins.

[0074] It is also preferable to include a dispersant that is soluble or dispersible in the solvent used in the coating agent. This improves the dispersibility of the polyvalent metal compound. Anionic surfactants or nonionic surfactants can be used as the dispersant. Examples of such surfactants include (poly)carboxylates, alkyl sulfates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, aromatic phosphate esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, alkyl allyl sulfates, polyoxyethylene alkyl phosphate esters, sorbitan alkyl esters, glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene sorbitan alkyl esters, polyoxyethylene alkyl allyl ethers, polyoxyethylene derivatives, polyoxyethylene sorbitol fatty acid esters, polyoxy fatty acid esters, and polyoxyethylene alkylamines. These surfactants may be used alone or in combination.

[0075] When an additive is contained in a coating agent containing a polyvalent metal compound (B) as a main component, the mass ratio of the polyvalent metal compound to the additive (polyvalent metal compound:additive) is preferably within a range of 30:70 to 99:1, and more preferably within a range of 50:50 to 98:2.

[0076] Examples of solvents used in coating agents containing a polyvalent metal compound (B) as a main component include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used alone or in combination of two or more. Among these, from the viewpoint of coatability, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred. Furthermore, from the viewpoint of manufacturability, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred.

[0077] When a coating agent containing a polycarboxylic acid polymer (A) and a polyvalent metal compound (B) is applied and dried to form a polycarboxylic acid polyvalent metal salt film, the polycarboxylic acid polyvalent metal salt film can be formed by mixing the polycarboxylic acid polymer (A), the polyvalent metal compound (B), a resin or dispersant soluble or dispersible in water or an alcohol as a solvent, and additives as needed, and applying and drying the resulting coating agent by a known coating method. Examples of coating methods include casting, dipping, roll coating, gravure coating, screen printing, reverse coating, spray coating, kit coating, die coating, metaling bar coating, chamber doctor combined coating, and curtain coating.

[0078] The thickness of the oxygen barrier film 15 is set depending on the required oxygen barrier properties and may be, for example, 0.05 to 5 μm. The thickness of the oxygen barrier film 15 is preferably 0.05 to 1 μm, and more preferably 0.1 to 0.5 μm. If the thickness of the oxygen barrier film 15 is 0.05 μm or more, sufficient oxygen barrier properties are likely to be obtained. If the thickness of the oxygen barrier film 15 is 1 μm or less, the presence or absence of protrusions derived from the AB agent on the first surface 10a has a significant effect on the oxygen barrier properties, making the present invention highly useful. Furthermore, if the thickness of the oxygen barrier film 15 is 1 μm or less, it is easy to form a uniform coated surface, and drying load and production costs can be reduced.

[0079] Gas barrier films having the organic-inorganic composite film or the polyvalent metal salt film of polycarboxylic acid as a gas barrier film exhibit excellent oxygen barrier properties even when subjected to boiling or retort sterilization, and when laminated with a sealant film, have sufficient adhesion strength and seal strength as packaging materials for boiling or retort treatment.Furthermore, they have advantages such as transparency not found in metal foils or metal vapor-deposited films, excellent flex resistance and stretch resistance, and no risk of generating harmful substances such as dioxins.

[0080] The sealant layer 18 is a layer that is bonded by heat sealing when the gas barrier film 100 is used to form a bag-shaped package or the like. Examples of materials for the sealant layer 18 include resin materials such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, and metal cross-linked products thereof. The thickness of the sealant layer 60 is determined depending on the purpose, but can be, for example, in the range of 15 to 200 μm.

[0081] The adhesive layer 17 bonds the sealant layer 18 and the oxygen barrier coating 15. By using the adhesive layer 17, the resin film that will become the sealant layer 18 and the substrate 10 on which the oxygen barrier coating 15 has been formed can be bonded together by dry lamination. An example of a material for the adhesive layer 17 is a two-component curing polyurethane adhesive.

[0082] A packaging material can be prepared by laminating a printed layer, an intervening film, a sealant layer, etc. on the oxygen barrier film 15. When laminating, an extrusion lamination method may be used in which a sealant is formed directly on the coating layer 30 without an adhesive.

[0083] The first surface 10a of the substrate 10 has a wavelength of 1370 to 1380 cm in infrared spectroscopy. -1 The peak intensity (I1) present at 1450-1460 cm -1 The intensity ratio between I1 and the peak intensity (I2) present at I1 is within the range of formula (1). That is, I1 is 1.65 times or less than I2. In this embodiment, this intensity ratio is achieved by the material properties of surface layer 11 that constitutes first surface 10a. I1 / I2≦1.65 …(1)

[0084] The value of the above formula (1) indicates the proportion of polypropylene in the resin components at the measurement point. I1 indicates the amount of polypropylene, and I2 indicates the sum of polyethylene and polypropylene. Therefore, the value of formula (1) is larger for homopolymers than for copolymers and terpolymers, and in copolymers and terpolymers, the value of formula (1) decreases as the amount of components other than polypropylene increases.

[0085] The inventors conducted extensive research into constructing a gas barrier film using a base material primarily composed of polypropylene. As a result, they found that, on the first surface 10a on which the oxygen barrier coating 15 is formed, the lower the proportion of polypropylene as a primary component, the better the adhesive strength of the gas barrier layer. The value of formula (1) on the first surface 10a is preferably 1.55 or less, and more preferably 1.50 or less.

[0086] As described above, the gas barrier film 100 of this embodiment is configured so that the gas barrier layer, which exhibits suitable gas barrier properties, is well bonded to the substrate and does not easily peel off, while maintaining a mono-material structure with polypropylene as the main component and reducing the environmental impact.

[0087] As a result of further investigation, the inventors found that the overall properties of the substrate 10 can be further improved by adding a base layer 12 having a larger value of formula (1) to the surface layer 11 including the first surface having the above-mentioned properties. By laminating a layer having a larger value of formula (1), i.e., a layer having a higher proportion of polypropylene than the layer including the first surface, the heat resistance of the substrate 10 as a whole is improved. As a result, sufficient heat can be applied to the substrate 10 when forming the oxygen barrier coating 15, thereby improving the barrier performance of the oxygen barrier coating 15. Furthermore, when the manufactured gas barrier film is subjected to a hot water treatment such as a retort treatment or a boiling treatment, the base layer 12 suppresses shrinkage of the surface layer 11, thereby effectively suppressing the occurrence of cracks or the like in the oxygen barrier coating 15, which would reduce the gas barrier function due to shrinkage, and the tendency of the oxygen barrier coating 15 to peel off from the substrate 10.

[0088] From this point of view, the value of the above formula (1) on the second surface 10b formed by the base layer 12 is preferably larger than the value on the first surface 10a, and more preferably 1.65 or more.

[0089] (Method for producing gas barrier film) The gas barrier film 100 can be produced by forming an underlayer 13, or both the underlayer 13 and the inorganic oxide layer 14, on the first surface 10a of the resin substrate 10, and then forming an oxygen barrier coating 15 on the underlayer 13 or the inorganic oxide layer 14.

[0090] The resin substrate 10 may be a commercially available product or may be manufactured by a known method.

[0091] As described above, the underlayer 13 is obtained by forming a coating film made of a coating agent on the first surface 10a of the resin substrate 10 by a wet coating method and drying this coating film. Examples of wet coating methods that can be used include known wet coating methods such as roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating. Methods for drying the coating film made of a coating agent include known drying methods such as hot air drying, hot roll drying, and infrared irradiation. Drying conditions include, for example, 90°C for 10 seconds.

[0092] The inorganic oxide layer 14 is obtained by forming a film on the underlayer 13 by the above-mentioned vacuum deposition method, sputtering method, ion plating method, plasma vapor deposition (CVD) method, or the like.

[0093] The oxygen barrier film 15 is obtained by forming a coating film made of the coating agent on the underlayer 13 or the inorganic oxide layer 14 by a wet coating method, followed by drying. Examples of wet coating methods that can be used include known wet coating methods such as roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating. Methods for drying the coating film made of the coating agent include known drying methods such as hot air drying, hot roll drying, and infrared irradiation. Drying conditions include, for example, 90°C for 10 seconds. The oxygen barrier film 15 may be formed by a single coating and drying process, or by multiple coatings and drying processes using the same or different coating agents.

[0094] (Action and effect) The gas barrier film 100 described above comprises a resin substrate 10 having at least a surface layer 11 and a base layer 12, an undercoat layer 13, or both the undercoat layer 13 and the inorganic oxide layer 14, on a first surface 10a of the resin substrate 10, and an oxygen barrier coating 15. The number of microparticles 16 contained in the surface layer 11 is 100 or less per 250 μm-by-250 μm area, and the average protruding height of the microparticles 16 is 2.5 μm or less, thereby enabling the inherent oxygen barrier properties to be fully exhibited and providing excellent oxygen barrier properties. Furthermore, because the thickness of the oxygen barrier coating 15 can be reduced, the gas barrier film 100 can be provided at low cost.

[0095] The reason why the oxygen barrier film 15 can sufficiently exhibit its inherent oxygen barrier properties even when it is thin is thought to be as follows.

[0096] Generally, resin substrates contain fine particles 16 of an AB agent to prevent blocking, and the AB agent creates convex portions on both sides (first and second sides) of the resin substrate. When a coating agent is applied to this resin substrate using a wet coating method, particularly if the amount of coating is small, the coating film does not form locally at the convex portions, resulting in defects. These defects become paths for gas permeation, and the oxygen barrier properties are not fully realized.

[0097] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above-described embodiments. The configurations and combinations thereof in the above-described embodiments are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible within the scope of the present invention.

[0098] The gas barrier film may further have a printing layer, an anchor coat layer, an overcoat layer, a light-shielding layer, an oxygen absorbing layer, an adhesive layer, a heat-sealable heat-fusible layer, or other functional layers, as necessary.

[0099] When the gas barrier film has a heat-sealable sealant layer 18, this sealant layer 18 is disposed on at least one outermost surface of the gas barrier film. By having the sealant layer 18, the gas barrier film becomes sealable by heat sealing. The sealant layer 18 can be laminated by a known method such as dry lamination or extrusion lamination using a known adhesive such as a polyurethane-based, polyester-based, or polyether-based adhesive. [Example]

[0100] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0101] [Materials used] <Resin substrate> α1: Biaxially oriented polypropylene film (product name: M-1, thickness 20 μm, one-sided corona treatment, manufactured by Mitsui Chemicals Tohcello Co., Ltd.). α2: Biaxially oriented polypropylene film (product name: ME-1, thickness 20 μm, one-sided corona treatment, manufactured by Mitsui Chemicals Tohcello Co., Ltd.). α3: Biaxially oriented polypropylene film (product name: P2111, thickness 20 μm, one side corona treated, manufactured by Toyobo Co., Ltd.). α4: Biaxially oriented polypropylene film (product name: P2102, thickness 20 μm, one-sided corona treatment, manufactured by Toyobo Co., Ltd.). α5: Biaxially oriented polypropylene film (product name: VPH2011, thickness 20 μm, one side corona treated, average particle size of AB agent on the corona treated side 2 μm, manufactured by AJPlast). α6: Biaxially oriented polypropylene film (product name: PB210J, thickness 20 μm, one side corona treated, manufactured by Futamura Chemical Co., Ltd.). α7: Biaxially oriented polypropylene film (product name: U-1, thickness 20 μm, one-sided corona treatment, manufactured by Mitsui Chemicals Tohcello Co., Ltd.). α8: Biaxially oriented polypropylene film (product name: P2171, thickness 20 μm, one-sided corona treatment, manufactured by Toyobo Co., Ltd.). α9: Biaxially oriented polypropylene film (product name: P2161, thickness 20 μm, one-sided corona treatment, manufactured by Toyobo Co., Ltd.). α10: Biaxially oriented polypropylene film (product name: VPH2011, thickness 20 μm, one side corona treated, average particle size of AB agent on the corona treated side 4 μm, manufactured by AJPlast).

[0102] <Production Example 1> Using Acrydic CL-1000 (DIC Corporation) as the acrylic polyol and TDI type curing agent Coronate 2030 (Tosoh Corporation) as the isocyanate compound, the acrylic polyol and isocyanate compound were mixed in a solids weight ratio of 6:4, and a dilution solvent (ethyl acetate) was used to prepare a mixed liquid (solids content: 2% by mass) for forming the undercoat layer.

[0103] <Production Example 2> An aqueous solution of polyvinyl alcohol resin (PVA, trade name: Poval PVA-105, manufactured by Kuraray Co., Ltd., polyvinyl alcohol with a saponification degree of 98-99% and a polymerization degree of 500) was dissolved, and an aqueous solution of tetraethoxysilane (TEOS) and γ-glycidoxypropyltrimethoxysilane (GPTMS, trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were each hydrolyzed with 0.02 mol / L hydrochloric acid. The aqueous solutions were mixed so that the weight ratio of PVA:TEOS:GPTMS was 40:50:10 before hydrolysis. A dilution solvent was then added to the mixed solution so that the weight ratio of the solvent components was 90:10 (water:isopropyl alcohol), to prepare a coating agent (5% by mass) for forming an organic-inorganic composite film.

[0104] [Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-4] The corona-treated surface of the resin substrate listed in Table 1 was coated with the mixture for forming the undercoat layer prepared in Production Example 1 using a gravure printer to form a coating film, and the coating was then dried in a 100°C oven for 10 seconds to form a 0.1 μm-thick undercoat layer. Next, a mixed material containing two or more of metallic silicon, silicon monoxide, and silicon dioxide was evaporated using an electron beam heating vacuum deposition device to form a 30 nm-thick inorganic oxide layer composed of silicon oxide on the undercoat layer. The organic-inorganic composite coating agent prepared in Production Example 2 was then coated on the inorganic oxide layer using a gravure printer to form a coating film, and the coating was then dried in a 100°C oven for 10 seconds to form a 0.3 μm-thick oxygen barrier coating composed of an organic-inorganic composite coating, resulting in the gas barrier films of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-4.

[0105] The evaluation items and measurement methods in each of the examples and comparative examples are shown below. <Infrared spectroscopic measurement of the first and second surfaces> Using a Fourier transform infrared spectrophotometer FT / IR-4000 (manufactured by JASCO Corporation), measurements were carried out on both sides of each substrate in the thickness direction before the gas barrier film was produced. The measurement conditions were as follows. Measurement conditions: ATR method Prism: Ge Resolution: 4cm -1 Accumulation count: 64

[0106] <Number of particles and average protruding height> The surface of the first surface 10a was observed using a laser microscope LEXT OLS-4000 (manufactured by Olympus Corporation), and the number of microparticles per unit area and the protruding height were measured. The observation magnification was 50 times. The number per unit area was measured in a randomly selected area of ​​257 μm × 259 μm (area 0.067 mm 2 ) and two adjacent areas of the same size to the right of it, and the arithmetic mean value of the three areas was used. The protrusion height was the arithmetic mean value of all the particles counted in the three areas.

[0107] <Oxygen barrier properties after hot water treatment> Each gas barrier film was bonded to a CPP (polypropylene film) using an adhesive to produce a gas barrier laminate film for retort processing, consisting of gas barrier film / adhesive / CPP. The adhesive was a two-component curing adhesive, Takelac® A620 (base) / Takenate® A65 (curing agent), manufactured by Mitsui Chemicals Polyurethanes. The CPP was a polypropylene film, Torayfan ZK93KM (60 μm), manufactured by Toray Advanced Films. The films were dry-laminated using a HIRANO TECSEED multi-coater TM-MC and aged at 40°C for 3 days. The oxygen barrier coating of the gas barrier film was positioned so that it faced the adhesive.

[0108] An A5-sized four-side sealed pouch was made from the obtained gas barrier laminate film, filled with 150 ml of tap water, and subjected to heat sterilization treatment (retort treatment) in hot water at 120°C for 30 minutes.

[0109] The gas barrier laminate film after the hot water treatment was measured for oxygen permeability (cm) under an atmosphere of 30°C and 70% RH using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON). 3 / (m 2 ·day·atm) was measured.

[0110] <Adhesion strength after hot water treatment> Immediately after production and after hot water treatment of the pouches of each example produced by the above procedure, test pieces were cut out from the part of each pouch that had been in contact with the contents in accordance with JIS Z1707, and the peel strength of the gas barrier layer 20 was measured as an index of adhesion using an Orientec Tensilon universal testing machine RTC-1250. Measurements were performed using two types of peel tests, T-peel and 180° peel, both in the normal state (Dry) and with the measurement site wet (Wet).

[0111] Table 1 shows the measurement results for Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-4.

[0112] [Table 1]

[0113] From the results shown in Table 1, the gas barrier films of Examples 1-1 to 1-6 had a value of 1.65 or less for the formula (1) on the first surface, and all of them maintained high adhesion between the substrate 10 and the sealant layer 18 after the hot water treatment. In addition, the oxygen permeability was 5.0 cc / m 2 It showed good gas barrier performance with a gas permeability of 1000 kJ / day atm or less.

[0114] On the other hand, the gas barrier films of Comparative Examples 1-1 to 1-3 had a value of formula (1) of more than 1.65 on the first surface, and had poor adhesion after hot water treatment. The gas barrier film of Comparative Example 1-4 had an average protrusion height of the fine particles 16 of more than 2.5 μm, and an oxygen permeability of 5.0 cc / m 2 ·day·atm and good gas barrier performance was not obtained.

[0115] <Production Example 3> 20 parts by mass of an aqueous solution of polyacrylic acid (Toagosei Aron A-10H, solids concentration 25% by mass) with a number average molecular weight of 200,000 was diluted with 58.9 parts by mass of distilled water, followed by the addition of 0.44 parts by mass of aminopropyltrimethoxysilane (APTMS, manufactured by Aldrich) and stirring to form a uniform solution, thereby preparing a coating agent whose main component is a polycarboxylic acid polymer.

[0116] <Production Example 4> A coating agent containing a polyvalent metal compound as the main component was prepared by mixing 100 parts by mass of an aqueous dispersion of zinc oxide particles (ZE143 manufactured by Sumitomo Osaka Cement) and 2 parts by mass of a curing agent Liofol HAERTER UR 5889-21 (manufactured by Henkel).

[0117] [Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-4] The corona-treated surface of the resin substrate listed in Table 2 was coated with the mixture for forming the undercoat layer prepared in Production Example 1 using a gravure printer to form a coating film, and then dried in a 100 ° C. oven for 10 seconds to form a 0.1 μm thick undercoat layer. Next, the coating agent mainly composed of the polycarboxylic acid polymer prepared in Production Example 3 was coated to form a coating film, and then dried in a 100 ° C. oven for 10 seconds to form a 0.2 μm thick polycarboxylic acid polymer film. Further, the coating agent mainly composed of the polyvalent metal compound prepared in Production Example 4 was coated on the polycarboxylic acid polymer film using a gravure printer to form a coating film, and then dried in a 100 ° C. oven for 10 seconds to form a 0.2 μm thick polyvalent metal compound film, forming an oxygen barrier film consisting of a polyvalent metal salt of polycarboxylic acid film, and the gas barrier films of Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-4 were obtained.

[0118] [Examples 2-7 to 2-10 and Comparative Examples 2-5 to 2-6] The mixed solution for forming the underlayer prepared in Production Example 1 was applied to the corona-treated surface of the resin substrate listed in Table 2 using a gravure printing machine to form a coating, and the coating was then dried in an oven at 100°C for 10 seconds to form an underlayer with a thickness of 0.1 μm. Next, a mixed material containing two or more of metallic silicon, silicon monoxide, and silicon dioxide was evaporated using a vacuum deposition device using an electron beam heating system to form an inorganic oxide layer made of silicon oxide with a thickness of 30 nm on the underlayer. Next, a coating agent mainly composed of the polycarboxylic acid polymer prepared in Production Example 3 was applied onto the formed inorganic oxide layer using a gravure printing machine to form a coating film, and the film was dried in a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Further, a coating agent mainly composed of the polyvalent metal compound prepared in Production Example 4 was applied onto the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and the film was dried in a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm. Thus, an oxygen barrier film consisting of a polyvalent metal salt of polycarboxylic acid was formed, and the gas barrier films of Examples 2-7 to 2-10 and Comparative Examples 2-5 to 2-6 were obtained.

[0119] [Examples 2-11 to 2-14 and Comparative Examples 2-7 to 2-8] The mixed solution for forming the underlayer prepared in Production Example 1 was applied to the corona-treated surface of the resin substrate listed in Table 2 using a gravure printing machine to form a coating, and the coating was dried in an oven at 100°C for 10 seconds to form an underlayer with a thickness of 0.1 μm. Next, metallic aluminum was evaporated using a vacuum deposition device using an electron beam heating system, and oxygen gas was introduced thereto to form an inorganic oxide layer made of aluminum oxide with a thickness of 20 nm on the underlayer. Next, a coating agent mainly composed of the polycarboxylic acid polymer prepared in Production Example 3 was applied onto the formed inorganic oxide layer using a gravure printing machine to form a coating film, and the film was dried in a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Further, a coating agent mainly composed of the polyvalent metal compound prepared in Production Example 4 was applied onto the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and the film was dried in a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm. Thus, an oxygen barrier film consisting of a polyvalent metal salt of polycarboxylic acid was formed, and the gas barrier films of Examples 2-11 to 2-14 and Comparative Examples 2-7 and 2-8 were obtained.

[0120] [Table 2]

[0121] From the results shown in Table 2, the gas barrier films of Examples 2-1 to 2-14 had a value of 1.65 or less for the formula (1) on the first surface, and all of them maintained high adhesion between the substrate 10 and the sealant layer 18 after the hot water treatment. In addition, the oxygen permeability was 5.0 cc / m 2 It showed good gas barrier performance with a gas permeability of 1000 kJ / day atm or less.

[0122] On the other hand, the gas barrier films of Comparative Examples 2-1 to 2-3 and 2-5 to 2-8 had a value of formula (1) of more than 1.65 on the first surface, and had poor adhesion after hot water treatment. The gas barrier film of Comparative Example 2-4 had an average protruding height of the fine particles 16 of more than 2.5 μm and an oxygen permeability of 5.0 cc / m 2 ·day·atm and good gas barrier performance was not obtained.

[0123] The above describes one embodiment of the present invention and examples, but the specific configuration is not limited to this embodiment, and includes modifications and combinations of configurations within the scope that does not deviate from the gist of the present invention.

[0124] The gas barrier film of the present invention may also have a printed layer provided at an appropriate position. An intervening film may also be attached to the coating layer to impart desired physical properties to the gas barrier film, such as pinhole resistance, cold resistance, heat resistance, bag drop resistance, and tear resistance.

[0125] Furthermore, the gas barrier film of the present invention does not necessarily require an adhesive layer or a sealant layer, and the adhesive layer or the sealant layer may be provided as needed, taking into consideration the specific use of the gas barrier film. [Industrial Applicability]

[0126] The gas barrier film of the present invention exhibits excellent adhesive strength and gas barrier properties even after hot water treatment. Furthermore, the quality can be stabilized even when the oxygen barrier coating is made thin, making it possible to reduce raw material costs.

[0127] The gas barrier film of the present invention can be suitably used, for example, as a packaging material, and can also be suitably used as a packaging material for boiling treatment and retort treatment. By using the gas barrier film of the present invention as a packaging material, the quality retention of the contents can be improved.

[0128] The gas barrier film of the present invention can also be used for applications other than packaging materials, such as electronic device-related films, solar cell films, various functional films for fuel cells, and substrate films. [Explanation of symbols]

[0129] 100 Gas barrier film 10 Resin substrate 11 Resin base material surface layer 12 Resin base material base layer 13 Base layer 14 Inorganic oxide layer 15 Oxygen barrier coating 16 Fine particles 17 Adhesive layer 18 Sealant Layer

Claims

1. A base material mainly composed of polypropylene, an oxygen barrier coating (excluding those containing an inorganic layered compound) on the first surface side of the substrate; a base layer, or both a base layer and an inorganic oxide layer, is provided between the substrate and the oxygen barrier coating; In infrared spectroscopy of the first surface, 1360 to 1390 cm -１ The peak intensity I1 present at 1440 to 1480 cm -１ The ratio of the peak intensity I2 present in the peak intensity I2 satisfies the following formula (1), I1 / I2≦1.55…(1) the first surface has protruding particles made of a material other than polypropylene; The number of the fine particles is 257 μm × 259 μm (area 0.067 mm ２ ) or less than 100 particles per A gas barrier film, wherein the average protrusion height of the fine particles is 2.5 μm or less.

2. The substrate is The resin layer has two or more resin layers including a base layer and a surface layer that constitutes the first surface, The value of I1 / I2 in infrared spectroscopy measurement of the resin layer on the second surface opposite to the first surface is The gas barrier film according to claim 1 , wherein the I1 / I2 value is greater than the I1 / I2 value on the first surface.

3. 3. The gas barrier film according to claim 1, wherein the thickness of the underlayer is 0.01 to 1 μm.

4. the underlayer contains an organic polymer as a main component, The gas barrier film according to any one of claims 1 to 3, wherein the organic polymer comprises at least one of a polyacrylic resin, a polyol resin, a polyurethane resin, a polyamide resin, or a reaction product of these organic polymers.

5. the underlayer and the inorganic oxide layer are both provided between the substrate and the oxygen barrier coating; 5. The gas barrier film according to claim 1, wherein the inorganic oxide layer has a thickness of 1 to 200 nm.

6. the underlayer and the inorganic oxide layer are both provided between the substrate and the oxygen barrier coating; 6. The gas barrier film according to claim 1, wherein the inorganic oxide layer is aluminum oxide or silicon oxide.

7. 7. The gas barrier film according to claim 1, wherein the oxygen barrier coating has a thickness of 0.05 to 1 μm.

8. 8. The gas barrier film according to claim 1, wherein the oxygen barrier coating is a coating containing at least one of a metal alkoxide, a hydrolyzate thereof, or a reaction product thereof, and a water-soluble polymer.

9. The gas barrier film according to claim 8 , wherein the oxygen barrier coating further comprises at least one of a silane coupling agent, a hydrolyzate thereof, and a reaction product thereof.

10. The gas barrier film according to any one of claims 1 to 7, wherein the oxygen barrier coating contains a polyvalent metal salt of a carboxylic acid that is a reaction product of a carboxy group of the polycarboxylic acid polymer (A) and a polyvalent metal compound (B).

11. The gas barrier film according to any one of claims 1 to 10, wherein the substrate further comprises a heat-sealable sealant layer, and the sealant layer is bonded to the oxygen barrier coating by an adhesive layer.

12. After hot water treatment at 120°C for 30 minutes, Oxygen permeability is 5.0 cc / m ２ ・day or less, The gas barrier film according to claim 11, wherein the peel strength between the substrate and the sealant layer is 1.0 N / 15 mm or more.

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