Gas barrier resin composition and gas barrier film

Abstract

To provide a gas barrier resin composition having excellent oxygen barrier properties and water vapor barrier properties even under high humidity conditions and a gas barrier film including the same.SOLUTION: A gas barrier resin composition is primarily composed of an acid group-containing polyurethane resin (A), a swellable inorganic laminar compound (B) and a crosslinker (C). The crosslinker (C) includes one or both of an oxazoline group-containing compound or a carbodiimide group-containing compound. Relative to 100 pts.wt. of the acid group-containing polyurethane resin (A), the swellable inorganic laminar compound (B) is 1-100 pts.wt. and the crosslinker (C) is 1-10 pts.wt..SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Gas barrier films that block oxygen and water vapor are widely used as packaging materials for foods, beverages, pharmaceuticals, electronic materials, precision components, and other items to suppress or prevent deterioration of the contents.

[0003] Films coated with polyvinyl chloride copolymer (PVDC) are known to have high gas barrier properties, but PVDC produces harmful gases when burned, and when incinerated at low temperatures it produces highly carcinogenic organic chlorine compounds, so its use tends to be avoided.

[0004] Films in which non-chlorine-based polyvinyl alcohol (PVA) or ethylene-vinyl alcohol copolymer (EVOH) is coated on a base film are also known, but because PVA and EVOH are highly hydrophilic, there is a problem in that their moisture barrier properties are significantly reduced in high-humidity environments.

[0005] To solve these problems, a gas-barrier aqueous resin composition containing a polyurethane resin having a total urethane group and urea group concentration of 25 to 60 wt % and containing acid groups, a swellable inorganic layered compound, and a polyamine compound has been proposed (see Patent Document 1). A film has also been proposed in which at least one gas-barrier layer containing a water-dispersible resin consisting solely of a polyurethane resin and water-swellable inorganic plate-like particles is formed on one or both sides of a thermoplastic resin substrate (see Patent Document 2). Furthermore, a gas-barrier film has been proposed in which a water-based coating agent is formed on one or both sides of a substrate film, in which the solids content ratio of the aqueous polyurethane resin, water-soluble polymer, and inorganic layered mineral is specified within a specific range relative to the total solids content (see Patent Document 3).

[0006] Although these films have less humidity dependency than PVA- or EVOH-coated films and have improved gas barrier properties under high-humidity conditions, the results are not fully satisfactory. In particular, when used to package foods with a high moisture content, it is difficult to fully demonstrate gas barrier properties. Furthermore, in recent years, from the perspective of reducing environmental impact, there has been a demand for further improvements in the water vapor barrier properties of coating agents in order to reduce the thickness of polypropylene in the base film and thereby the amount of polypropylene used. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-139436 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-047209 [Patent Document 3] Japanese Patent Application Publication No. 2014-214232 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above points, and provides a gas barrier resin composition that has good oxygen barrier properties and water vapor barrier properties even under high humidity conditions, and a gas barrier film using the same. [Means for solving the problem]

[0009] That is, the first invention is a gas barrier resin composition comprising, as main components, an acid group-containing polyurethane resin (A), a swellable inorganic layer compound (B), and a crosslinking agent (C), wherein the crosslinking agent (C) contains either or both of an oxazoline group-containing compound and a carbodiimide group-containing compound, and the amount of the swellable inorganic layer compound (B) and the amount of the crosslinking agent (C) are 1 to 100 parts by weight and 1 to 10 parts by weight, respectively, per 100 parts by weight of the acid group-containing polyurethane resin (A). 0.05 to 1.5 parts by weight of the amino group-containing silane coupling agent (D),The present invention relates to a gas barrier resin composition comprising:

[0011] No. 2 The invention is 1 of The invention relates to a gas barrier resin composition in which the acid group-containing polyurethane resin (A) has an acid value of 5 to 60 mgKOH / g.

[0012] No. 3 The present invention provides a first film on at least one surface of a base film. or 2 The present invention relates to a gas barrier film having a gas barrier layer (X) formed of any one of the gas barrier resin compositions of the present invention laminated thereon.

[0013] No. 4 The invention is 3 The invention relates to a gas barrier film in which a diffraction peak is observed within a diffraction angle 2θ range of 4° to 7° in the X-ray diffraction spectrum of the gas barrier layer (X) obtained by X-ray diffraction using CuKα rays under a condition of 25°C. [Effects of the Invention]

[0014] According to a first aspect of the present invention, the gas barrier resin composition is a gas barrier resin composition whose main components are an acid group-containing polyurethane resin (A), a swellable inorganic layered compound (B), and a crosslinking agent (C), and the crosslinking agent (C) contains either or both of an oxazoline group-containing compound and a carbodiimide group-containing compound, and the amount of the swellable inorganic layered compound (B) and the amount of the crosslinking agent (C) are 1 to 100 parts by weight and 1 to 10 parts by weight, respectively, per 100 parts by weight of the acid group-containing polyurethane resin (A). 0.05 to 1.5 parts by weight of the amino group-containing silane coupling agent (D), Since the resin composition contains In addition, when the resin composition is coated on a substrate film, the adhesion to the substrate film is improved, making it possible to omit an anchor layer and improve lamination strength.

[0016] No. 2 According to the gas barrier resin composition of the present invention, 1 ofIn the present invention, since the acid value of the acid group-containing polyurethane resin (A) is 5 to 60 mgKOH / g, it is possible to obtain a resin composition having better oxygen barrier properties and water vapor barrier properties even under high humidity conditions.

[0017] No. 3 According to the gas barrier film of the present invention, the first or 2 Since the gas barrier layer (X) made of any one of the gas barrier resin compositions of the present invention is laminated on the film, the film can have good gas barrier properties.

[0018] No. 4 According to the gas barrier film of the present invention, 3 In the invention, in the X-ray diffraction spectrum of the gas barrier layer (X) obtained by X-ray diffraction using CuKα rays under conditions of 25°C, a diffraction peak is observed within the diffraction angle 2θ range of 4° to 7°, and therefore the film can have good gas barrier properties. DETAILED DESCRIPTION OF THE INVENTION

[0019] The gas barrier resin composition of the present invention is a resin composition that is applied to the surface of a substrate such as a film to form a gas barrier layer, and that imparts oxygen barrier properties and water vapor barrier properties to the substrate such as a film. The gas barrier resin composition of the present invention is composed mainly of components (A), (B), and (C), and optionally contains an amino group-containing silane coupling agent (D) as an additive.

[0020] Component (A) is an acid group-containing polyurethane resin. The acid group-containing polyurethane resin is preferably prepared by a known method, and a polyurethane resin dispersion dispersed in water is preferably used. For example, a polyisocyanate component is reacted with a polyol component (or a diamine component) to form an isocyanate group-terminated prepolymer, which is then neutralized with a primary neutralizer and dissolved or dispersed in an aqueous medium to obtain an isocyanate group-terminated prepolymer. A chain extender component is then added as appropriate to react the prepolymer, and the organic solvent is removed to prepare the acid group-containing polyurethane resin (A).

[0021] Examples of the polyisocyanate component include aromatic diisocyanates, aliphatic diisocyanates, araliphatic diisocyanates, and alicyclic diisocyanates, and any of these may be used. In particular, it is preferable to use xylylene diisocyanate or hydrogenated xylylene diisocyanate.

[0022] The polyol component preferably contains a diol having 2 to 6 carbon atoms and an active hydrogen group-containing compound containing an anionic group. Examples of diols having 2 to 6 carbon atoms include ethylene glycol, propylene glycol, butanediol, and pentanediol. Examples of active hydrogen group-containing compounds containing anionic groups include organic compounds having both an anionic group such as a carboxylic acid and two or more active hydrogen groups such as hydroxyl groups or amino groups. Examples include dimethylolpropionic acid, dimethylolbutanoic acid, and 2,2-dimethylolhexanoic acid, with dimethylolpropionic acid being preferred. The acid value of the acid group-containing polyurethane resin (A) can be adjusted by the amount of the active hydrogen group-containing compound containing an anionic group used.

[0023] The acid value of the acid group-containing polyurethane resin (A) is 5 to 100 mgKOH / g, preferably 5 to 60 mgKOH / g. If the acid value of the acid group-containing polyurethane resin (A) is less than 5 mgKOH / g, the water solubility or water dispersibility of the acid group-containing polyurethane resin (A) may be insufficient, potentially resulting in reduced uniform dispersion with other materials and reduced dispersion stability of coating agents made from the gas barrier resin composition. If the acid value of the acid group-containing polyurethane resin exceeds 100 mgKOH / g, the water resistance and gas barrier properties of the coating film formed from the coating agent may be reduced. By adjusting the acid value of the acid group-containing polyurethane resin (A) to 5 to 60 mgKOH / g, the crosslinking reaction with the crosslinking agent (C) occurs more appropriately, allowing the coating film formed from the gas barrier resin composition to exhibit excellent gas barrier properties even in a high-humidity atmosphere. The acid value of the acid group-containing polyurethane resin is measured in accordance with JIS K 0070 (1992).

[0024] The acid groups of the acid group-containing polyurethane resin (A) are neutralized with a neutralizing agent or a base. Examples of the neutralizing agent include conventional bases, such as organic bases, inorganic bases, and alkali metal carbonates. Examples of the organic base include tertiary amines (trimethylamine, triethylamine, etc.), and the like. 1-4 Examples of inorganic bases include alkanolamines such as alkylamines, dimethylethanolamine, methyldiethanolamine, triethanolamine, and triisopropanolamine, and heterocyclic amines such as morpholine. Examples of inorganic bases include ammonia and alkali metal hydroxides (lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.). Examples of alkali metal carbonates include sodium carbonate and potassium carbonate. These bases can be used alone or in combination of two or more. From the viewpoint of gas barrier properties, volatile bases, for example, tri-C such as triethylamine, are preferred. 1-3 Alkylamines, alkanolamines such as dimethylethanolamine, and ammonia are preferably used.

[0025] The chain extender is a nitrogen-containing compound having an active hydrogen atom, particularly at least one selected from diamines, hydrazines, and hydrazine derivatives. Examples of diamine components used as chain extenders include aliphatic amines, aromatic amines, and alicyclic amines. Examples of aliphatic amines include C amines such as ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, and octamethylenediamine. 2-10 Examples of the aromatic amines include m- or p-phenylenediamine, 1,3- or 1,4-xylylenediamine, or a mixture thereof. Examples of the alicyclic amines include hydrogenated xylylenediamine, bis(4-aminocyclohexyl)methane, isophoronediamine, bis(4-amino-3-methylcyclohexyl)methane, etc., hydroxyl group-containing diamines [2-[(2'-aminoethyl)amino]ethanol, 2-aminoethylaminopropanol, 2-(3'-aminopropyl)aminoethanol (3-(2'-hydroxyethyl)aminopropylamine), etc.], and amino C amines such as hydroxyl group-containing diamines [2-[(2'-aminoethyl)amino]ethanol, 2-aminoethylaminopropanol, 2-(3'-aminopropyl)aminoethanol (3-(2'-hydroxyethyl)aminopropylamine], etc.]. 2-6 Alkylamino C 2-3 Alkyl alcohols and the like.

[0026] Hydrazine and hydrazine derivatives include hydrazine and hydroxyl group-containing hydrazines (hydrazino C such as 2-hydrazinoethanol). 2-3 Alkyl alcohols, etc.), dicarboxylic acid hydrazides (aliphatic dicarboxylic acid hydrazides (succinic acid dihydrazide, adipic acid dihydrazide, glutaric acid dihydrazide, dodecanedioic acid dihydrazide, etc. C 4-20 Alkane-dicarboxylic acid dihydrazides), aromatic dicarboxylic acid hydrazides (C such as isophthalic acid dihydrazide) 6-10 arene-dicarboxylic acid hydrazide, etc. These chain extender components can be used alone or in combination of two or more.

[0027] Among these chain extenders, those having 8 or less carbon atoms (C 2-8, especially C 2-6 ) low molecular weight chain extenders, for example, diamines (e.g., ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, etc.) 2-6 Examples of the chain extender include alkylenediamines, 2-aminoethylaminoethanol, xylylenediamine, hydrazine, and hydrazine derivatives (e.g., 2-hydrazinoethanol, adipic acid dihydrazide, etc.). If necessary, a trifunctional or higher polyamine component (e.g., polyamine, polyhydrazide, etc.) can be used in combination with the chain extender.

[0028] Component (B) is a swellable inorganic layered compound. Swellable inorganic layered compounds are clay minerals composed of extremely thin unit crystals and capable of coordinating or absorbing solvents between the unit crystal layers, resulting in swelling. Examples of swellable inorganic layered compounds include hydrous silicates (phyllosilicate minerals, etc.), kaolinite-group clay minerals (halloysite, kaolinite, endelite, dickite, nacrite, etc.), antigorite-group clay minerals (antigorite, chrysotile, etc.), smectite-group clay minerals (montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, stevensite, etc.), vermiculite-group clay minerals (vermiculite, etc.), and mica or mica-group clay minerals (muscovite, phlogopite, and other micas, margarite, tetrasilylic mica, taeniolite, etc.). These clay minerals may be natural or synthetic. The swellable inorganic layered compounds can be used alone or in combination of two or more. Among these inorganic layered compounds, smectite clay minerals (such as montmorillonite) and mica clay minerals (such as water-swellable mica) are particularly preferred.

[0029] The swellable inorganic layered compound usually has an average particle size of 20 μm or less, preferably about 100 nm to 10 μm, and may have an aspect ratio of, for example, about 50 to 5,000, preferably about 100 to 3,000, and more preferably about 200 to 2,000.

[0030] The swellable inorganic layered compound (B) is contained in an amount of 1 to 100 parts by weight per 100 parts by weight of the acid group-containing polyurethane resin (A). The amount is preferably 3 to 50 parts by weight, and more preferably 5 to 40 parts by weight. Although increasing the mixing ratio of the water-swellable swellable inorganic layered compound (B) improves gas barrier properties, even if the amount of the swellable inorganic layered compound (B) is 100 parts by weight or more per 100 parts by weight of the acid group-containing polyurethane resin (A), no improvement in gas barrier properties under high humidity conditions is observed. Furthermore, flexibility decreases when processed into a film, making the film difficult to handle. Therefore, taking into consideration gas barrier properties and convenience of the film, the amount of the swellable inorganic layered compound (B) contained is preferably 1 to 100 parts by weight per 100 parts by weight of the acid group-containing polyurethane resin (A).

[0031] Component (C) is a crosslinking agent. The crosslinking agent includes either an oxazoline group-containing compound or a carbodiimide group-containing compound, or both. The oxazoline group-containing compound is a compound having one or more oxazoline groups as crosslinkable functional groups in one molecule. Examples of the oxazoline group-containing compound include 2,2'-bis-(2-oxazoline), 2,2'-methylene-bis-(2-oxazoline), 2,2'-ethylene-bis-(2-oxazoline), 2,2'-trimethylene-bis-(2-oxazoline), 2,2'-tetramethylene-bis-(2-oxazoline), 2,2'-hexamethylene-bis-(2-oxazoline), 2,2'-octamethylene-bis-(2-oxazoline), and the like. Examples include oxazoline group-containing polymers such as dioxazolines such as 2,2'-ethylene-bis-(4,4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis-(2-oxazoline), 2,2'-m-phenylene-bis-(4,4'-dimethyl-2-oxazoline), bis-(2-oxazolinylcyclohexane) sulfide, and bis-(2-oxazolinylnorbornane) sulfide. These oxazoline group-containing compounds can be used alone or in combination of two or more.

[0032] A carbodiimide group-containing compound is a compound having one or more carbodiimide groups per molecule. A polycarbodiimide compound can be obtained, for example, by subjecting a polyisocyanate to a decarboxylation condensation reaction in the presence of a known carbodiimide catalyst. Examples of polyisocyanates constituting carbodiimides include the polyisocyanates exemplified above as polyisocyanate components. Specific examples include the aromatic polyisocyanates, araliphatic polyisocyanates (including xylylene diisocyanate), aliphatic polyisocyanates, alicyclic polyisocyanates (including hydrogenated xylylene diisocyanate), and derivatives thereof. The carbodiimide catalyst is not particularly limited, and examples include known catalysts such as phospholene and phospholene oxide. The decarboxylation condensation reaction of polyisocyanate using a carbodiimide catalyst may be a solvent-free reaction or may be a reaction in the presence of a solvent.

[0033] More specifically, examples of carbodiimides include tetramethylxylylene diisocyanate-based carbodiimides and 4,4'-methylenebis(cyclohexyl isocyanate)-based carbodiimides. Examples include carbodiimides, pentamethylene diisocyanate-based carbodiimides, etc. These carbodiimides and carbodiimide group-containing compounds can be used alone or in combination of two or more.

[0034] These crosslinking agents may be oxazoline group-containing compounds or carbodiimide group-containing compounds, and may be used alone or in combination of two or more. The crosslinking agent (C) is contained in an amount of 1 to 10 parts by weight per 100 parts by weight of the acid group-containing polyurethane resin (A). Preferably, it is contained in an amount of 2 to 10 parts by weight, and more preferably, about 3 to 10 parts by weight. By keeping the content of crosslinking agent (C) within this range, when the resin composition is coated on a substrate film, adhesion to the substrate film is improved and gas barrier properties can also be improved.

[0035] The combination of the acid group-containing polyurethane resin (A), the swellable inorganic layered compound (B), and the crosslinking agent (C) exhibits high gas barrier properties even under high humidity conditions. While the mechanism by which the resin composition of the present invention exhibits gas barrier properties is unclear, in a solvent (coating) such as water, the solvent is coordinated between the unit crystal layers, absorbed, and swelled, and cleavage occurs between the layers through dispersion treatment. When the cleaved swellable inorganic layered compound (B) is mixed with the acid group-containing polyurethane resin (A) and the crosslinking agent (C) in the presence of a solvent, the acid group-containing polyurethane resin (A) and the crosslinking agent (C) are present between the randomly dispersed unit crystal layers of the swellable inorganic layered compound (B). The crosslinking agent (C) is inserted between the layers, expanding the spaces between the layers of the swellable inorganic layered compound (B), thereby promoting interlayer cleavage. A coating containing the resin composition in this state is applied to a substrate (substrate film). In the subsequent drying step, the swellable inorganic layered compound (B) sandwiches the acid group-containing polyurethane resin (A) and the crosslinking agent (C) between its unit crystal layers, causing their crystal faces to overlap in a complex manner. If cleavage between the layers is promoted, the layers will overlap in a more complex manner, improving the labyrinth effect and presumably making it easier to restrict gas permeation.

[0036] Furthermore, the crosslinking agent (C) can bond with the acid groups of the acid group-containing polyurethane resin (A) to form a crosslinked structure. This is thought to enhance the cohesive strength between the acid group-containing polyurethane resin (A) and the crosslinking agent (C), and between the acid group-containing polyurethane resin (A), the crosslinking agent (C), and the swellable inorganic layered compound (B). This is thought to effectively suppress the permeation of gas molecules such as oxygen and water vapor. Therefore, in compositions that do not contain the swellable inorganic layered compound (B) and the crosslinking agent (C), no improvement in gas barrier properties can be expected.

[0037] An amino group-containing silane coupling agent (D) may also be added as appropriate. Examples of the amino group-containing silane coupling agent (D) that can be used include N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and 3-aminopropyltrimethoxysilane. The amino group-containing silane coupling agent is effective in improving the adhesion of the gas barrier resin composition to the substrate film. These amino group-containing silane coupling agents (D) may be used alone or in combination of two or more.

[0038] The amino group-containing silane coupling agent (D) is preferably contained in an amount of 0.05 to 1.5 parts by weight per 100 parts by weight of the acid group-containing polyurethane resin (A). It is preferably contained in an amount of about 0.1 to 1.0 part by weight. If the amount of amino group-containing silane coupling agent (D) is too large, the viscosity of the resin composition increases, gelation occurs, and the gas barrier properties also decrease. Therefore, from the viewpoint of improving adhesion to the substrate, it is preferable to add the amino group-containing silane coupling agent (D) in an amount within the above range.

[0039] The gas barrier resin composition may contain various additives other than the amino group-containing silane coupling agent (D) as needed, provided that the gas barrier properties are not impaired. Examples of such additives include stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, fillers, and crystal nucleating agents.

[0040] The method for preparing the dispersion of the gas barrier resin composition is not particularly limited, and the gas barrier resin composition can be prepared, for example, by mixing a dispersion in which the swellable inorganic layered compound (B) is uniformly dispersed in a solvent with a dispersion or aqueous solution of the acid group-containing polyurethane resin (A) and the crosslinking agent (C). The crosslinking agent (C) can be added at any stage, and may be added to the dispersion of the swellable inorganic layered compound (B) or the dispersion containing the acid group-containing polyurethane resin (A), or may be added to a mixture of these dispersions.

[0041] To improve gas barrier properties, it is preferable that the acid group-containing polyurethane resin (A) and the swellable inorganic layered compound (B) are dispersed extremely uniformly in the dispersion of the gas barrier resin composition. In particular, the swellable inorganic layered compound (B) may undergo secondary aggregation in the dispersion of the gas barrier resin composition. For this reason, it is preferable to disperse or mix the swellable inorganic layered compound (B) in a solvent and then use a mechanical forced dispersion treatment that applies shear force or shear stress, such as a known dispersion treatment using a homomixer, colloid mill, jet mill, kneader, sand mill, ball mill, three-roll mill, ultrasonic disperser, etc., to uniformly disperse the swellable inorganic layered compound (B).

[0042] The gas barrier film includes a substrate film and a gas barrier layer made of a gas barrier resin composition laminated on at least one surface of the substrate film. The gas barrier layer is formed by coating the gas barrier resin composition on the surface of the substrate film.

[0043] As the substrate film, a film made of a thermoplastic resin is usually used. Examples of thermoplastic resins include polyolefin resins (e.g., polyethylene, polypropylene, propylene-ethylene copolymer, etc.), polyester resins (e.g., polyethylene terephthalate, etc.), polyamide resins (e.g., nylon 6, nylon 66, etc.), vinyl resins (e.g., polyvinyl alcohol, ethylene-vinyl alcohol copolymer, etc.), cellophane, etc. These resins can be used alone or in combination of two or more. Preferred substrate films include polypropylene resin films, polyethylene terephthalate resin films, and polyamide resin films.

[0044] The substrate film may be a monolayer film or a monolayer or laminate film using multiple resins. The substrate film may also be a laminated substrate film of another substrate (metal such as aluminum, paper, etc.) and a thermoplastic resin, or a resin film vapor-deposited with a metal such as aluminum or a metal oxide such as silica. Furthermore, the substrate film may be an unstretched film or a uniaxially or biaxially oriented film, and may be subjected to a surface activation treatment such as corona treatment, flame treatment, plasma treatment, anchor coating treatment, or primer coating treatment from the viewpoint of adhesion to the gas barrier coating film. The thickness of the substrate film varies depending on the application, but is preferably 3 to 200 μm, preferably 5 to 120 μm, and more preferably 9 to 100 μm.

[0045] The method for applying the gas barrier resin composition to a substrate film or the like is not particularly limited, and known coating methods can be used, such as gravure coating, reverse coating, roll coating, bar coating, spray coating, air knife coating, comma coating, dipping, etc. After the gas barrier resin composition is applied or laminated on the substrate film by the above-mentioned coating method, the solvent is removed in a drying step to form a film, thereby forming a gas barrier layer and obtaining a gas barrier film.

[0046] The mass per unit area of ​​the gas barrier layer is 0.1 to 10 g / m 2 is preferable, and 0.2 to 5 g / m 2 More preferably, 0.3 to 2 g / m 2 Within this range, the gas barrier properties and appearance are improved. The thickness of the gas barrier layer is preferably 0.2 to 5 μm, and more preferably 0.3 to 2 μm. Within this range, the gas barrier properties and appearance are improved.

[0047] The drying method in the drying step is not particularly limited, but examples thereof include hot air drying, infrared heating, microwave heating, hot roll heating, and heating with superheated steam. These drying methods may be used alone or in combination. The drying temperature is not particularly limited, but when water or a mixed solvent of water and an organic solvent is used as the solvent, it is usually preferable to set the drying temperature to 50 to 160°C.

[0048] X-ray diffraction is a phenomenon observed as a result of the interference of scattered X-rays from each atom in a material, and is a method for analyzing the regular structural arrangement of atoms in crystals and other structures. In X-ray diffraction, when X-rays with a wavelength similar to the spacing between atoms (0.5 Å to 3 Å) are incident, the X-rays scattered by each atom interfere in a specific direction, generating strong X-rays. When the wavelength (λ) of the incident X-rays is an integer (n) multiple, the wave phases coincide (interfere), resulting in strong diffracted X-rays (satisfying the condition in equation (i) below). θ is the Bragg angle, and 2θ (the angle between the direction of the incident X-rays and the direction of the diffracted X-rays) is called the diffraction angle. 2dsinθ=nλ (i)

[0049] The crystal is irradiated with monochromatic X-rays of a fixed wavelength λ, and θ is observed. The interplanar spacing (the spacing between crystal lattice planes) d can be calculated from the measured θ and the above formula (1). In the above formula (i), n represents the phase difference between the interfering waves. In the examples of the present invention, a first-order diffraction beam (n=1) is usually used. In the present invention, a diffraction peak is observed within a diffraction angle 2θ range of 4° to 7° in the X-ray diffraction spectrum of the gas barrier layer (Y) obtained by X-ray diffraction using CuKα rays at 25°C. In the examples, the gas barrier film used was left at room temperature (20°C, 50% RH) for 24 hours.

[0050] Under these conditions, for example, if a dispersion of a typical water-swellable inorganic layered compound in which sodium ions are interposed between the layers of the swellable inorganic layered compound is applied to a substrate or the like and the X-ray diffraction spectrum of the coating film is measured after sufficient heat drying, a spectrum is observed around 2θ = 9.1°. If a monohydrate layer is formed between the crystalline layers, a spectrum is observed around 2θ = 7.5°. In particular, if the heat drying is insufficient or the particle size of the swellable inorganic layered compound is large, the monohydrate layer between the crystalline layers is likely to remain even after heat drying, and two peaks around 2θ = 9.1° and 7.5° tend to be observed.

[0051] The heat-drying conditions for the dispersion of the water-swellable inorganic layered compound are preferably, for example, drying at a drying temperature of 70°C to 100°C for 10 hours or more using a hot air oven or the like. If heat-drying is insufficient, a higher drying temperature or a longer drying time may be used. In the gas barrier layer formed from the gas barrier resin composition of the present invention, as described above, the swellable inorganic layered compound in the gas barrier layer is thought to have its crystal faces intertwined and overlapping with each other, with the acid group-containing polyurethane resin and crosslinking agent component sandwiched between its unit crystal layers. The infiltration of the crosslinking agent between the layers expands the gap between the inorganic layered compound layers, promoting interlayer cleavage and increasing the interlayer distance. Therefore, in the X-ray diffraction spectrum of the gas barrier layer (Y), a diffraction peak is observed within the diffraction angle 2θ range of 4° to 7°. [Example]

[0052] [Materials used] The inventors used the following materials to prepare a gas barrier resin composition.

[0053] <Component (A)> Acid group-containing polyurethane resin (a1): "Takelac (registered trademark) WPB-341A" manufactured by Mitsui Chemicals, Inc., solid content concentration 30%, acid value 27 mg KOH / g

[0054] <(B) component> Swellable inorganic layered compound (b1): "Somasif (registered trademark) MEB-3" manufactured by Katakura Co-op Agri Co., Ltd., solid content concentration 8%, average particle size 2.2 μm Swellable inorganic layered compound (b2): Katakura Co-op Agri Co., Ltd., "Somasif (registered trademark) ME200B-4T", solid content concentration 8%, average particle size 7.4 μm Swellable inorganic layered compound (B2): Katakura Co-op Agri Co., Ltd., "Somasif (registered trademark) ME300B-4T", solid content 7.9%, average particle size 16.5 μm

[0055] <(C) component> Crosslinking agent (c1): Nippon Shokubai Co., Ltd., "Oxazoline group-containing compound WS-700", solid content 25% Crosslinking agent (c2): Nippon Shokubai Co., Ltd., "Oxazoline group-containing compound WS-300", solid content 10% Crosslinking agent (c3): Nisshinbo Chemical Inc.'s "Carbodiimide group-containing compound V-02-L2", solid content 40% Crosslinking agent (c4): Nisshinbo Chemical Inc.'s "Carbodiimide group-containing compound V-02," solid content 40%

[0056] <(D) component> Amino group-containing silane coupling agent (d1): Shin-Etsu Chemical Co., Ltd., "KBM-903," solid content 100% When adding to the prototype, 0.5 g of the amino group-containing silane coupling agent was added to 99.5 g of water, and the mixture was stirred with a stirrer for 1 hour to prepare a solution with a concentration of 0.5%.

[0057] [Preparation of Gas Barrier Resin Composition] <Prototype example 1> To 43.48 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to 4 wt %, 1.04 g of crosslinker (c1) and 55.48 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 53.76 g of this aqueous dispersion of swellable inorganic layered compound (b1) and crosslinker (c1), 15.58 g of a dispersion of acid group-containing polyurethane resin (a1) and 30.66 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 1.

[0058] <Prototype example 2> To 38.46 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to 4 wt%, 1.85 g of crosslinker (c1) and 59.69 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 59.33 g of this aqueous dispersion of swellable inorganic layered compound (b1) and crosslinker (c1), 15.21 g of a dispersion of acid group-containing polyurethane resin (a1) and 25.46 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 2.

[0059] <Prototype example 3> To 38.46 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to 4 wt%, 1.15 g of crosslinker (c3) and 60.38 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 59.33 g of this aqueous dispersion of swellable inorganic layered compound (b1) and crosslinker (c3), 15.21 g of a dispersion of acid group-containing polyurethane resin (a1) and 25.46 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 3.

[0060] <Prototype example 4> To 55.80 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to 4 wt%, 0.67 g of crosslinker (c3) and 43.53 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2.5%). To 82.56 g of this aqueous dispersion of swellable inorganic layered compound (b1) and crosslinker (c3), 12.29 g of a dispersion of acid group-containing polyurethane resin (a1) and 5.15 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 4.

[0061] <Prototype 5> To 38.46 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to 4 wt%, 0.92 g of crosslinking agent (c1), 0.58 g of (c3), and 60.04 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 59.33 g of this aqueous dispersion of swellable inorganic layered compound (b1) and crosslinking agents (c1) and (c3), 15.21 g of a dispersion of acid group-containing polyurethane resin (a1) and 25.46 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 5.

[0062] <Prototype Example 6> To 41.67 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to 4 wt%, 1.00 g of crosslinking agent (c1), 0.83 g of (c2), and 56.50 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 55.65 g of this aqueous dispersion of swellable inorganic layered compound (b1) and crosslinking agents (c1) and (c2), 15.46 g of a dispersion of acid group-containing polyurethane resin (a1) and 28.90 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 6.

[0063] <Prototype Example 7> To 42.55 g of a 4 wt% aqueous dispersion of swellable inorganic layered compound (b1), 1.02 g of crosslinker (c1), 8.51 g of a solution of amino-group-containing silane coupling agent (d1), and 47.91 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 54.71 g of this aqueous dispersion of swellable inorganic layered compound (b1), crosslinker (c1), and amino-group-containing silane coupling agent, 15.52 g of a dispersion of acid-group-containing polyurethane resin (a1) and 29.77 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 7.

[0064] <Prototype example 8> To 37.74 g of a 4 wt% aqueous dispersion of swellable inorganic layered compound (b1), 1.13 g of crosslinker (c3), 7.55 g of a solution of amino-group-containing silane coupling agent (d1), and 53.58 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 60.23 g of this aqueous dispersion of swellable inorganic layered compound (b1), crosslinker (c3), and amino-group-containing silane coupling agent, 15.15 g of a dispersion of acid-group-containing polyurethane resin (a1) and 24.62 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 8.

[0065] <Prototype Example 9> To 37.74 g of a 4 wt% aqueous dispersion of swellable inorganic layered compound (b2), 1.13 g of crosslinker (c3), 7.55 g of a solution of amino-group-containing silane coupling agent (d1), and 53.58 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 60.23 g of this aqueous dispersion of swellable inorganic layered compound (b2), crosslinker (c3), and amino-group-containing silane coupling agent, 15.15 g of a dispersion of acid-group-containing polyurethane resin (a1) and 24.62 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 9.

[0066] <Prototype example 10> To 40.82 g of a 4 wt% aqueous dispersion of swellable inorganic layered compound (b2), 0.33 g of crosslinker (c1), 0.61 g of (c3), 8.16 g of a solution of amino-group-containing silane coupling agent (d1), and 50.41 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 56.58 g of this aqueous dispersion of swellable inorganic layered compound (b1), crosslinker (c1), (c3), and amino-group-containing silane coupling agent, 15.39 g of a dispersion of acid-group-containing polyurethane resin (a1) and 28.03 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Prototype Example 10.

[0067] <Prototype Example 11> To 34.48 g of an aqueous dispersion of swellable inorganic layered compound (b3) adjusted to 4 wt%, 0.83 g of crosslinker (c1), 1.03 g of (c3), and 63.66 g of water were added and stirred for 1 hour using a Homo Disper (total solids concentration 2%). To 64.63 g of this aqueous dispersion of swellable inorganic layered compound (b3) and crosslinkers (c1) and (c3), 14.86 g of a dispersion of acid group-containing polyurethane resin (a1) and 20.51 g of water were added and stirred for 30 minutes using a Homo Disper to obtain the gas barrier resin composition of Prototype Example 11.

[0068] <Comparative Example 1> To 13.07 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to a concentration of 4 wt %, 17.42 g of a dispersion of acid group-containing polyurethane resin (a1) and 69.51 g of water were added, and the mixture was stirred for 30 minutes using a homodisper to obtain a gas barrier resin composition of Comparative Example 1.

[0069] <Comparative Example 2> To 23.96 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to a concentration of 4 wt %, 15.97 g of a dispersion of acid group-containing polyurethane resin (a1) and 60.07 g of water were added, and the mixture was stirred for 30 minutes using a homodisper to obtain a gas barrier resin composition of Comparative Example 2.

[0070] <Comparative Example 3> To 33.17 g of an aqueous dispersion of swellable inorganic layered compound (b1) adjusted to a concentration of 4 wt %, 14.74 g of a dispersion of acid group-containing polyurethane resin (a1) and 52.08 g of water were added, and the mixture was stirred for 30 minutes using a homodisper to obtain a gas barrier resin composition of Comparative Example 3.

[0071] <Comparative Example 4> To 48.78 g of a 4 wt% aqueous dispersion of swellable inorganic layered compound (b1), 9.76 g of a solution of amino group-containing silane coupling agent (d1) and 41.46 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 48.91 g of this aqueous dispersion, 15.91 g of a dispersion of acid group-containing polyurethane resin (a1) and 35.18 g of water were added and stirred for 30 minutes using a homodisper to obtain a gas barrier resin composition of Comparative Example 4.

[0072] <Comparative Example 5> To 45.45 g of a 4 wt% aqueous dispersion of swellable inorganic layered compound (b1), 36.36 g of a solution of amino group-containing silane coupling agent (d1) and 18.18 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 51.84 g of this aqueous dispersion, 15.71 g of a dispersion of acid group-containing polyurethane resin (a1) and 32.45 g of water were added and stirred for 30 minutes using a homodisper to obtain a gas barrier resin composition of Comparative Example 5.

[0073] <Comparative Example 6> 18.61 g of the dispersion of acid group-containing polyurethane resin (a1), 0.67 g of crosslinking agent (c1), and 80.72 g of water were added and stirred for 30 minutes using a homodisper to obtain a gas barrier resin composition of Comparative Example 6.

[0074] <Comparative Example 7> 18.08 g of the dispersion of acid group-containing polyurethane resin (a1), 0.81 g of crosslinking agent (c3), and 81.10 g of water were added and stirred for 30 minutes using a homodisper to obtain a gas barrier resin composition of Comparative Example 7.

[0075] <Comparative Example 8> To 30.30 g of a 4 wt% aqueous dispersion of swellable inorganic layered compound (b1), 0.73 g of crosslinking agent (c1), 1.52 g of (c3), and 67.45 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 71.33 g of this aqueous dispersion, 14.41 g of a dispersion of acid group-containing polyurethane resin (a1) and 14.25 g of water were added and stirred for 30 minutes using a homodisper to obtain the gas barrier resin composition of Comparative Example 8.

[0076] <Comparative Example 9> To 27.03 g of a 4 wt% aqueous dispersion of swellable inorganic layered compound (b1), 1.08 g of crosslinking agent (c1), 1.62 g of (c3), and 70.27 g of water were added and stirred for 1 hour using a homodisper (total solids concentration 2%). To 77.65 g of this aqueous dispersion, 13.99 g of a dispersion of acid group-containing polyurethane resin (a1) and 8.36 g of water were added and stirred for 30 minutes using a homodisper to obtain a gas barrier resin composition of Comparative Example 9.

[0077] [Creating gas barrier film] Next, a biaxially stretched polypropylene film (manufactured by Futamura Chemical Co., Ltd., "CKC", thickness 25 μm) was used as the base film to prepare gas barrier films corresponding to each prototype and comparative example. The gas barrier resin composition was applied to the corona-treated surface of the base film using a wire bar until the weight (coating amount) after drying was 0.5 g / m 2 The coated surfaces were then dried in an oven at 90°C for 30 seconds, and the same gas barrier resin composition was then coated on each coated surface and dried in the same manner until the total weight (coating amount) after drying was 1.0 g / m 2 A gas barrier film having the following properties was prepared. Note that the gas barrier resin composition of Comparative Example 5 generated a large number of aggregates and could not be applied to the substrate film, so the measurements described below could not be performed.

[0078] In addition, for the gas barrier resin composition of Prototype Example 11, a gas barrier film was also produced using a biaxially oriented polypropylene film (manufactured by Futamura Chemical Co., Ltd., "CKC", thickness 20 μm) as the base film, and this was used as the gas barrier film of Prototype Example 12.

[0079] Tables 1 and 2 show the types of components (A), (B), (C), and (D) used in the gas barrier resin compositions of Prototype Examples 1 to 11 and Comparative Examples 1 to 9, as well as the amounts (parts by weight) of components (B), (C), and (D) added per 100 parts by weight of component (A).

[0080] [Table 1]

[0081] [Table 2]

[0082] [Evaluation of gas barrier film performance] The oxygen permeability and water vapor permeability were measured to evaluate the gas barrier performance of the gas barrier films of Prototype Examples 1 to 12 and Comparative Examples 1 to 9. The oxygen permeability and water vapor permeability were also measured for the biaxially oriented polypropylene film (manufactured by Futamura Chemical Co., Ltd., "CKC", thickness 25 μm) used as the base film as Reference Example 1, and for the biaxially oriented polypropylene film (manufactured by Futamura Chemical Co., Ltd., "CKC", thickness 20 μm) as Reference Example 2. The results are summarized in Tables 3 and 4.

[0083] <Oxygen permeability measurement> Oxygen permeability (cm 3 / m 2 The oxygen permeability (atm·day) was measured in accordance with JIS K 7126 (2006) using an oxygen permeability measuring device ("OX-TRAN (registered trademark) 2 / 20 MH" manufactured by Mocon Co., Ltd.) under conditions of a temperature of 20°C and a relative humidity of 80% (80% RH) and a temperature of 20°C and a relative humidity of 90% (90% RH).

[0084] <Measurement of water vapor permeability> Water vapor permeability (g / m 2 ·day) was measured in accordance with JIS K 7129 (2008) using a water vapor transmission rate measuring device (manufactured by Mocon, "PERMATRAN-W (registered trademark) 3 / 33") under conditions of a temperature of 40°C and a relative humidity of 90% (90% RH).

[0085] [X-ray diffraction measurement] X-ray diffraction measurements were also performed on the gas barrier films of Prototype Examples 1 to 12 and Comparative Examples 1 to 9, and the 2θ (°) and interplanar spacing (Å) were measured as the X-ray diffraction spectrum of the gas barrier film on the side where the gas barrier layer was laminated. The gas barrier films of each prototype and comparative example were left at room temperature (20°C, 50% RH) for 24 hours before use. The X-ray diffraction spectra of the gas barrier films were measured at 25°C using an X-ray diffractometer (Rigaku Corporation, "RINT-2000"; X-ray source: CuKα, λ=1.5405Å, voltage: 40 kV, current: 20 mA, receiving slit: 1 / 2°, scattering slit: 1 / 2°, scan speed: 2° / min). When no diffraction peaks were observed, the result was marked "-".

[0086] [Table 3]

[0087] [Table 4]

[0088] [Results and Discussion] As shown in Tables 3 and 4, good results were obtained for both oxygen permeability and water vapor permeability in Prototypes 1 to 11. Furthermore, in the X-ray diffraction spectrum, diffraction peaks were observed within the diffraction angle 2θ range of 4 to 7°. Prototype 12 exhibited an oxygen permeability equivalent to that of Prototype 11, and a water vapor permeability equivalent to that of Reference Example 1 (biaxially oriented polypropylene film (thickness 25 μm)). This demonstrates that by using the gas barrier resin composition of the present invention, it is possible to reduce the amount of polypropylene used by an amount equivalent to 5 μm of the thickness of the base film.

[0089] When Prototype Examples 1 to 3, 5, and 6 were compared with Comparative Example 2, which did not contain the crosslinking agent (C) and contained the same type and amount of swellable inorganic layered compound (B), it was found that Prototype Examples 1 to 3, 5, and 6 exhibited better oxygen barrier properties and water vapor barrier properties. When Prototype Examples 7 to 9 were compared with Comparative Example 4, which did not contain the crosslinking agent (C) and contained the same amount of amino group-containing silane coupling agent (D) as an additive, it was found that Prototype Examples 7 to 9 exhibited better oxygen barrier properties and water vapor barrier properties. Furthermore, when Prototype Examples 1 to 3, 5, and 6 were compared with Comparative Examples 8 and 9, which contained a higher amount of crosslinking agent (C), Prototype Examples 1 to 3, 5, and 6 exhibited better oxygen barrier properties and water vapor barrier properties. From the above, it was understood that adding a crosslinking agent (C) improved the gas barrier properties of the gas barrier layer, but that adding more than a certain amount of crosslinking agent (C) actually impaired the gas barrier properties.

[0090] Furthermore, when Prototypes 1 and 3 were compared with Comparative Examples 6 and 7, which did not contain the swellable inorganic layered compound (B), Prototypes 1 and 3 exhibited good gas barrier properties, confirming the improvement in gas barrier properties due to the inclusion of the swellable inorganic layered compound (B). Furthermore, when Prototypes 3 and 4, which differ in the content of the swellable inorganic layered compound (B), were compared, the gas barrier properties remained the same even when the content of the swellable inorganic layered compound (B) was increased. Therefore, excessively increasing the content of the swellable inorganic layered compound (B) not only failed to achieve the expected effect, but also may have a negative impact on the processability of the film. In Comparative Example 5, a large number of aggregates were generated, preventing the formation of a uniform coating film.

[0091] As shown above, it was confirmed that Prototypes 1 to 12 have improved not only oxygen barrier properties but also water vapor barrier properties under high humidity conditions. This not only makes them suitable for packaging foods with high moisture content, but also allows for thinner films used as substrates, such as oriented polypropylene films, thereby reducing the amount of polypropylene used and the environmental impact. [Industrial Applicability]

[0092] The gas barrier resin composition of the present invention can be applied to a substrate film to form a gas barrier layer, thereby obtaining a gas barrier film, which has good oxygen barrier properties and water vapor barrier properties even under high humidity conditions. In other words, the gas barrier resin composition of the present invention can impart excellent gas barrier properties to a substrate film without undergoing complicated processes.

Claims

1. A gas barrier resin composition comprising, as main components, an acid group-containing polyurethane resin (A), a swellable inorganic layered compound (B), and a crosslinking agent (C), The crosslinking agent (C) contains either or both of an oxazoline group-containing compound and a carbodiimide group-containing compound, For 100 parts by weight of the acid group-containing polyurethane resin (A), 1 to 100 parts by weight of the swellable inorganic layered compound (B); 1 to 10 parts by weight of the crosslinking agent (C), and 0.05 to 1.5 parts by weight of an amino group-containing silane coupling agent (D). A gas barrier resin composition comprising:

2. 2. The gas barrier resin composition according to claim 1, wherein the acid group-containing polyurethane resin (A) has an acid value of 5 to 60 mgKOH / g.

3. A gas barrier film comprising a substrate film and a gas barrier layer (X) made of the gas barrier resin composition according to claim 1 or 2 laminated on at least one surface of the substrate film.

4. 4. The gas barrier film according to claim 3, wherein a diffraction peak is observed within a diffraction angle 2θ range of 4° to 7° in an X-ray diffraction spectrum of the gas barrier layer (X) obtained by X-ray diffraction using CuKα rays under a condition of 25°C.

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