Resin composition, film and multilayer structure

Abstract

To provide a resin composition that is excellent in gas barrier properties under high humidity conditions, especially oxygen barrier properties under high humidity conditions.SOLUTION: A resin composition contains a hydrophilic resin and a metallic compound, where the metallic compound satisfies the general formula (1) defined by Ma(OH)bAn-(2a-b) / n. (In the formula, M represents a metal species; A represents an anionic ligand other than a hydroxy ligand with a valence of n-, provided that A is not O (oxo ligand); n is an integer greater than or equal to 1; and a and b are numbers greater than 0 and satisfy a / b=0.1 to 10.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, and more particularly to a resin composition from which a film having high gas barrier properties can be obtained under high humidity conditions. [Background technology]

[0002] Hydrophilic resins such as polyvinyl alcohol-based resins are excellent in strength, transparency, gas barrier properties, etc., and are therefore formed into films and widely used as various packaging materials, particularly as packaging materials for foods, medicines, and other items that require prevention of deterioration due to oxygen. However, hydrophilic resins are susceptible to the influence of humidity because they have many hydroxyl groups, and gas barrier properties are significantly reduced in high humidity environments.

[0003] As an example of a film with improved gas barrier properties, Patent Document 1 discloses a gas barrier film material that contains poorly water-soluble inorganic fine particles having an average particle size of 500 nm or less and a water-soluble or water-dispersible polymer compound, in which the poorly water-soluble inorganic fine particles are ionic crystals synthesized by reacting an inorganic compound containing one or more essential components selected from aluminum, silicon, zinc, zirconium, silver, and tin, or a salt thereof, with one or more compounds selected from organic acids, inorganic acids, and salts thereof.

[0004] In addition, Patent Document 2 discloses a method for producing a water-soluble polymer, at least one of a metal alkoxide, a hydrolyzate thereof, and tin chloride, and a compound represented by the general formula (R 1 Si(OR 2 )3)n(However, R 1 is an organic functional group, R 2 and a compound represented by the formula (I) CH3, C2H5, or C2H4OCH3).

[0005] Furthermore, Patent Document 3 discloses a method for producing a gas barrier laminate, which includes the steps of forming a coating film containing zinc ions, at least one of a metal alkoxide and a hydrolyzate thereof, and a water-soluble polymer on the surface of a substrate film or a laminate containing the same, and forming a gas barrier layer on the surface. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-338821 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-221864 [Patent Document 3] Japanese Patent Application Publication No. 2018-089567 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] However, the gas barrier films disclosed in the above Patent Documents 1 to 3 do not have sufficient gas barrier properties under high humidity conditions, and further improvement is required.

[0008] Under these circumstances, an object of the present invention is to provide a resin composition that has excellent gas barrier properties under high humidity, particularly excellent oxygen barrier properties under high humidity. [Means for solving the problem]

[0009] However, the present inventors have found that by further incorporating a specific metal compound into a resin composition containing a hydrophilic resin, the resin composition can have excellent gas barrier properties under high humidity conditions.

[0010] That is, a first gist of the present invention is a resin composition containing a hydrophilic resin and a metal compound, wherein the metal compound satisfies the following general formula (1). M a (OH) bA n- (2a-b) / n ···(1) (The above M represents a metal species, and A represents an anionic ligand other than a hydroxy ligand having a valence of n. However, A does not include O (oxo ligand). n is an integer of 1 or more, and a and b are numbers greater than 0, satisfying a / b=0.1 to 10.) The second aspect of the present invention is a film containing the resin composition according to the first aspect, and the third aspect is a multilayer structure having at least one layer made of the film according to the second aspect. [Effects of the Invention]

[0011] The resin composition of the present invention contains a hydrophilic resin and a metal compound, and the metal compound satisfies the general formula (1). When hydrophilic resin molecules and water molecules are present around the metal compound that satisfies the general formula (1), layers of the metal compound peel off from each other, and these fine layered structural units interact with the hydrophilic resin at the molecular level. As a result, it is presumed that a film containing this resin composition will have excellent gas barrier properties, particularly oxygen barrier properties, under high humidity conditions. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments for carrying out the present invention will be specifically described, but the present invention is not limited to these.

[0013] The resin composition of the present invention contains a hydrophilic resin and a metal compound, and the metal compound satisfies the following general formula (1). M a (OH) b A n- (2a-b) / n ···(1) (The above M represents a metal species, and A represents an anionic ligand other than a hydroxy ligand having a valence of n. However, A does not include O (oxo ligand). n is an integer of 1 or more, and a and b are numbers greater than 0, satisfying a / b=0.1 to 10.) Each component will be described below.

[0014] [Hydrophilic resin] Specific examples of the hydrophilic resin used in the present invention include water-soluble resins such as vinyl alcohol resins, polysaccharides, acrylic resins, polyether resins, etc. The above hydrophilic resins may be used alone or in combination of two or more.

[0015] Furthermore, the hydrophilic resin preferably has the following properties when formed into a film. That is, it is preferable that a film having a thickness of 30 μm is prepared using the above hydrophilic resin and the area change rate when the film is immersed in water at 25° C. for 2 hours is 105% or more. The area change rate can be calculated by the following formula. Area change rate (%) = film area after immersion / film area before immersion × 100 Specific hydrophilic resins will be described in detail below.

[0016] [Vinyl alcohol resin] The vinyl alcohol resins mentioned above exclude resins generally known as ethylene-vinyl alcohol copolymer resins (ethylene content: 20 to 60 mol%), and examples thereof include polyvinyl alcohol (hereinafter referred to as "PVA") resins.

[0017] The PVA resin is usually preferably an unmodified PVA resin, but a modified PVA resin may also be used.

[0018] The unmodified PVA resin can usually be produced by polymerizing a vinyl ester monomer and then saponifying the polymer. The modified PVA resin can be produced by saponifying a polymer of a vinyl ester monomer and another unsaturated monomer, or by post-modifying an unmodified PVA resin.

[0019] Examples of the vinyl ester monomer include aliphatic vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, and vinyl trifluoroacetate, and aromatic vinyl esters such as vinyl benzoate. Among these, aliphatic vinyl esters having 3 to 20 carbon atoms are preferred, more preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms, with vinyl acetate being particularly preferred. These are usually used alone, but multiple types may be used simultaneously as necessary.

[0020] Examples of the other unsaturated monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid, or their salts or mono- or di-alkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallylsulfonic acid, or their salts; alkyl vinyl ethers; N-acrylamidomethyltrimethylammonium chloride, allyl trimethylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, polyisoprene, and the like. Examples of suitable alkoxy groups include polyoxyalkylene (meth)allyl ethers such as polyoxyethylene (meth)allyl ether and polyoxypropylene (meth)allyl ether, polyoxyalkylene (meth)acrylates such as polyoxyethylene (meth)acrylate and polyoxypropylene (meth)acrylate, polyoxyalkylene (meth)acrylamides such as polyoxyethylene (meth)acrylamide and polyoxypropylene (meth)acrylamide, polyoxyethylene (1-(meth)acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, and polyoxypropylene vinylamine. These may be used alone or in combination of two or more. The term "(meth)allyl" as used above means allyl or methallyl, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acrylic" means acrylic or methacrylic, respectively.

[0021] The PVA resin can be obtained by any known polymerization method, saponification method, or post-modification method.

[0022] The amount of the other unsaturated monomer introduced and the amount of modification by post-modification are appropriately set depending on the type of monomer, but are usually 15 mol % or less, particularly 10 mol % or less. If the amount introduced or the amount of modification is too high, the crystallinity of the PVA resin tends to decrease, and the gas barrier properties of the PVA resin when made into a film tend to decrease.

[0023] The average saponification degree of the PVA resin is usually 70 to 100 mol%, preferably 80 to 100 mol%, particularly preferably 85 to 100 mol%, and even more preferably 90 to 99.99 mol%. If the average saponification degree is less than 70 mol%, the oxygen permeability tends to increase under high humidity conditions. The average saponification degree is measured in accordance with JIS K 6726.

[0024] The average degree of polymerization of the PVA resin is usually 100 to 4,000, preferably 200 to 3,000, and particularly preferably 250 to 2,500. If the average degree of polymerization is too low, mechanical properties such as film strength tend to decrease, while if it is too high, handling tends to become difficult, for example, it becomes difficult to make an aqueous solution. The average degree of polymerization is measured in accordance with JIS K 6726.

[0025] Furthermore, two or more PVA-based resins differing in the type of modification, the amount of modification, the average degree of saponification, the average degree of polymerization, etc. may be used in combination.

[0026] [Polysaccharide] Examples of the polysaccharides include starch and cellulose. Examples of the starch include natural starches such as corn starch and potato starch, and modified starches such as etherified starch, esterified starch, cross-linked starch, grafted starch, roasted dextrin, enzyme-modified dextrin, pregelatinized starch, and oxidized starch. Examples of the cellulose include carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl cellulose, nitrocellulose, cationized cellulose, and metal salts thereof such as sodium salts.

[0027] [Acrylic resin] Examples of the acrylic resin include polyacrylamide, polyacrylic acid, and metal salts thereof such as sodium salts.

[0028] [Polyether resin] Examples of the polyether resin include polyethylene glycol and polypropylene glycol.

[0029] Among the above hydrophilic resins, vinyl alcohol resins and polysaccharides are preferred because they have excellent oxygen barrier properties under high humidity conditions, PVA resins, modified starch (particularly soluble starch), and hydroxypropyl methylcellulose are more preferred, and unmodified PVA resins are most preferred.

[0030] The hydrophilic resin is preferably the main component of the resin composition of the present invention, and the content of the hydrophilic resin in the entire resin composition is usually 80% by weight or more, preferably 90% by weight or more, and particularly preferably 95% by weight or more, with the upper limit usually being 99.99% by weight.

[0031] [Metal compound] The metal compound used in the present invention has a structure in which specific structural units are arranged in layers with specific interplanar spacing.

[0032] The structural unit contains a metal, a hydroxy ligand, and an anionic ligand other than a hydroxy ligand, and is represented by the following chemical formula (1). M a (OH) b A n- (2a-b) / n···(1) (The above M represents a metal species, and A represents an anionic ligand other than a hydroxy ligand having a valence of n. However, A does not include O (oxo ligand). n is an integer of 1 or more, and a and b are numbers greater than 0, satisfying a / b=0.1 to 10.)

[0033] In the above chemical formula (1), examples of M include Na, K, Ca, Mg, Si, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, and Zn. These metal species may be contained alone or in combination with two or more. Among them, Al, Si, Mg, Ni, Co, and Zn are preferred, Ni, Co, and Zn are particularly preferred, and Zn is particularly preferred, from the viewpoint of excellent oxygen barrier properties under high humidity conditions.

[0034] In the above chemical formula (1), examples of A include RO (alkoxy ligand), ROCO (carboxylic acid ligand), CO3, NO3, SO3, PO4, BO3, F, Br, Cl, etc. (R is an alkyl chain, and C m H 2m+1 It is generally represented by a chemical formula in which m=1 to 20. However, the alkyl chain may have a functional group such as an OH group as long as it does not impair the effects of the present invention. However, O (oxo ligand) is excluded as A. These anionic ligands may be contained alone or in combination of two or more. Among them, from the viewpoint of interaction with the hydrophilic resin, NO3, Cl, RO, and ROCO are preferred, ROCO is particularly preferred, and among them, CHOCO is particularly preferred.

[0035] The metal compound used in the present invention may contain water molecules.

[0036] Specific examples of the metal compound include layered compounds containing Zn as a metal species, and among these, a Zn-containing layered compound represented by the chemical formula [Zn(OH)(CHCO) 2·2H0] is preferred because of its excellent oxygen barrier properties under high humidity conditions.

[0037] The metal compound can be obtained, for example, by reacting a metal-containing compound under specific conditions.

[0038] Examples of the metal-containing compound include organic acid metal salts and inorganic metal salts.

[0039] Examples of organic acids constituting the organic acid metal salts include monocarboxylic acids such as acetic acid, dicarboxylic acids such as succinic acid, oxalic acid, and tartaric acid, and tricarboxylic or higher carboxylic acids such as citric acid and ethylenediaminetetraacetic acid. These may be used alone or in combination of two or more. The organic acid metal salts may be hydrates or anhydrides. As the organic acid metal salt, a monovalent carboxylic acid metal salt is preferred from the viewpoint of excellent oxygen barrier properties under high humidity conditions, a metal acetate is particularly preferred, and zinc acetate or a hydrate thereof is particularly preferred.

[0040] Examples of the inorganic metal salt include metal fluorides, chlorides, bromides, iodides, and oxoacids. These may be used alone or in combination of two or more. The inorganic metal salt may be a hydrate or an anhydride. As the inorganic metal salt, metal chlorides and oxoacids are preferred from the viewpoint of excellent oxygen barrier properties under high humidity conditions, and zinc chloride, zinc nitrate, or hydrates thereof are particularly preferred.

[0041] The metal compound used in the present invention can be obtained using the above-mentioned metal-containing compound, for example, by (I) a method of reacting a metal-containing compound in the presence of a base, or (II) a method of reacting a metal-containing compound by heating. Each method will be described in detail below.

[0042] [Method (I)] The above method (I) is a method in which a metal-containing compound is reacted in the presence of a base.

[0043] Examples of the base used in the above method (I) include hydroxides of alkali metals or alkaline earth metals. Among them, hydroxides of alkali metals are preferred, and sodium hydroxide is particularly preferred, because they have excellent reactivity with metal-containing compounds.

[0044] In the reaction between the metal-containing compound and the base, the metal-containing compound and the base are usually mixed in a solution and then reacted. The method for mixing the metal-containing compound and the base is not particularly limited, and examples thereof include a method of mixing a solution in which a metal-containing compound is dissolved with a solution in which a base is dissolved, and a method of mixing a slurry liquid in which a metal-containing compound is dispersed with a solution in which a base is dissolved. Among these, from the viewpoint of reaction efficiency, a method of mixing a solution in which a metal-containing compound is dissolved with a solution in which a base is dissolved is preferred. Furthermore, when an organic acid metal salt is used as the metal-containing compound, a method of adding a solution in which an organic acid metal salt is dissolved to a solution in which a base is dissolved and mixing them is preferred, and when an inorganic metal salt is used, a method of adding a solution in which a base is dissolved to a solution in which an inorganic metal salt is dissolved and mixing them is preferred.

[0045] The solvent for dissolving the metal-containing compound and the base is not particularly limited as long as it can dissolve the metal-containing compound and the base, and examples thereof include water and lower alcohols having 1 to 5 carbon atoms, such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol. These may be used alone or in combination of two or more. Among these, water is preferred from the viewpoint of ease of post-treatment.

[0046] The concentration of the metal-containing compound in the solution in which the metal-containing compound is dissolved is usually 0.5 to 3 mol / L, and preferably 1 to 2 mol / L. The concentration of the base in the solution obtained by dissolving the base in the solvent is usually 0.01 to 100 mol / L, preferably 0.1 to 30 mol / L, and particularly preferably 1 to 10 mol / L. If the concentrations of the metal-containing compound and the base are lower than the above ranges, the reaction tends to proceed insufficiently, whereas if the concentrations of the metal-containing compound and the base are higher than the above ranges, side reactions tend to occur.

[0047] The molar ratio of the metal-containing compound to the base (metal-containing compound:base) is usually 0.5:2 to 2:0.5, preferably 0.8:1.5 to 1.5:0.8, and particularly preferably 0.9:1.2 to 1: 1. If the molar ratio is outside the above range, the reaction tends not to proceed sufficiently.

[0048] The pH when reacting the metal-containing compound with the base is usually 4 to 9, preferably 5 to 8. If the pH is too low below the above range, the reaction tends not to proceed sufficiently. If the pH is too high above the above range, the generated metal compound tends to decompose. The pH is adjusted by adjusting the amounts of the solution in which the metal-containing compound is dissolved and the solution in which the base is dissolved.

[0049] The reaction temperature in the above reaction is usually 15 to 60° C., preferably 20 to 40° C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, whereas if the reaction temperature is too high, the metal-containing compound tends to be decomposed by heat, making it difficult to obtain the desired metal compound. The reaction time is usually 0.5 to 5 hours, preferably 1 to 3 hours, and the reaction may be carried out under normal pressure.

[0050] After the reaction, the metal compound is obtained as a precipitate. The obtained metal compound may be used as it is, but it is preferable to purify the metal compound by washing, pulverization, etc. before use.

[0051] [Method (II)] The above method (II) is a method in which a metal-containing compound is heated to cause a reaction.

[0052] The above method (II) is usually carried out by heating a solution in which a metal-containing compound is dissolved while stirring.

[0053] As the solvent for dissolving the metal-containing compound, the solvents listed in the above method (I) can be used. Among them, water and alcohols are preferred, and a mixed solvent of water and 1-propanol is particularly preferred.

[0054] As for the heating conditions, the solution may be heated to a temperature of usually 20 to 100° C., preferably 50 to 95° C., and particularly preferably 70 to 90° C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, whereas if the reaction temperature is too high, the metal-containing compound tends to be decomposed by heat, making it difficult to obtain the desired metal compound. The reaction time is usually 0.1 to 100 hours, preferably 0.5 to 30 hours, and particularly preferably 1 to 10 hours, and the reaction may be carried out under normal pressure.

[0055] After the reaction, the metal compound is obtained as a precipitate. The obtained metal compound may be used as it is, or may be purified by washing, pulverization, or the like before use.

[0056] Generally, a metal compound refers to, for example, a metal salt, a metal oxide, a metal complex, a simple metal, or an alloy, but the metal compounds obtained by each of the above methods are, as described above, metal layer compounds having a structure in which the layered structural units represented by the chemical formula (1) are layered at a specific interplanar spacing. Therefore, when hydrophilic resin molecules or water molecules are present around the metal compound, the layers of the metal compound are peeled off, and these peeled fine layered structural units interact with the hydrophilic resin at the molecular level, resulting in presumably excellent oxygen barrier properties.

[0057] In order to provide excellent gas barrier properties, particularly oxygen barrier properties, under high humidity conditions, the metal compound used in the present invention preferably has a main X-ray diffraction peak at 2θ=2 to 15°, more preferably at 2θ=2 to 9°, and particularly preferably at 2θ=3 to 8°, when measured by wide-angle X-ray diffraction using CuKα radiation. When the main X-ray diffraction peak falls within the above range, the metal compound and the hydrophilic resin interact to increase the polarity of the hydrophilic resin, resulting in excellent oxygen barrier properties under high humidity conditions.

[0058] The interlayer distance (distance between layers) of the metal compound is preferably 0.01 to 50 nm, more preferably 0.1 to 30 nm, from the viewpoint of interaction with the hydrophilic resin molecules and water molecules. The interlayer distance of the metal compound can be calculated from the Bragg equation based on the diffraction position of the strongest peak in the 2θ range of 2 to 15° when analyzed by X-ray diffraction.

[0059] The molecular weight of the layered structural unit peeled off from the metal compound is preferably 100 to 10,000, particularly preferably 200 to 2,000, in order to enable interaction with the hydrophilic resin at the molecular level.

[0060] The layered structural unit is preferably hydrophilic in view of interaction with the molecules of the hydrophilic resin. Furthermore, it is preferable that the layered structural unit does not decompose even when left standing in an environment of 20°C and 90% RH for 1,000 hours.

[0061] The content of the metal compound in the resin composition of the present invention in terms of metal is usually 0.01 to 10 parts by weight, preferably 0.1 to 8 parts by weight, and particularly preferably 0.2 to 4 parts by weight, relative to 100 parts by weight of the hydrophilic resin. If the content of the metal compound is too low, the oxygen barrier property under high humidity conditions tends to decrease, while if the content of the metal compound is too high, whitening and reduced transparency tend to occur when the composition is made into a film or the like. When the resin composition contains a plurality of metal compounds of different metal species, the total amount of all the metal compounds contained in the resin composition is defined as the content. The content of the metal compounds can be determined by the standard addition method using ICP-MS.

[0062] [Other ingredients] The resin composition of the present invention may contain additives generally added to resin compositions, such as heat stabilizers, antioxidants, antistatic agents, colorants, ultraviolet absorbers, lubricants, plasticizers, light stabilizers, surfactants, antibacterial agents, desiccants, antiblocking agents, flame retardants, crosslinking agents, curing agents, foaming agents, crystal nucleating agents, antifogging agents, biodegradable additives, silane coupling agents, oxygen absorbers, etc. These may be used alone or in combination of two or more.

[0063] The resin composition of the present invention can be obtained by mixing a hydrophilic resin, a metal compound, and, if necessary, other components.

[0064] <Resin composition> The resin composition of the present invention contains the hydrophilic resin and a metal compound satisfying the following general formula (1): M a (OH) b A n- (2a-b) / n ···(1) (The above M represents a metal species, and A represents an anionic ligand other than a hydroxy ligand having a valence of n. However, A does not include O (oxo ligand). n is an integer of 1 or more, and a and b are numbers greater than 0, satisfying a / b=0.1 to 10.)

[0065] It is presumed that the layered structure of the metal compound satisfying the general formula (1) interacts with the hydrophilic resin, increasing the polarity of the hydrophilic resin, resulting in the effect of excellent oxygen barrier properties under high humidity conditions.

[0066] Furthermore, in the present invention, in order to achieve excellent gas barrier properties, particularly oxygen barrier properties, under high humidity conditions, the film preferably has a main X-ray diffraction peak at 2θ=2 to 15°, more preferably at 2θ=2 to 9°, and particularly preferably at 2θ=3 to 8°, when measured by wide-angle X-ray diffraction using CuKα radiation.

[0067] When measured by wide-angle X-ray diffraction using the CuKα ray, the main X-ray diffraction peak observed at 2θ=2 to 15° is preferably a peak derived from a metal compound satisfying the general formula (1) above.

[0068] The wide-angle X-ray diffraction is measured under the following conditions. [Measurement conditions] Equipment used: D8 DISCOVER (manufactured by Bruker Japan) Detector: 2D detector VANTEC-500 (manufactured by Bruker Japan) Voltage: 50kV ·Current: 100mA Camera length: 100mm ·Measurement method: Reflection method Accumulation time: 30 minutes Wavelength: CuKα line (Kα1 and Kα2 are not separated) Detector position: 2θ=10° ·X-ray incident angle: θ=0.3° ·Conditions for one-dimensionalization in the 2θ direction: 2θ = 0 to 35°, azimuth angle (chi) = -95 to -85° ·One-dimensionalization in the azimuth angle direction: azimuth angle (chi) = -180 to 0° When linearizing in the azimuthal direction, linearization is performed in the azimuthal direction in a range of 1.0° so that the peak with the strongest diffraction intensity is included in the 2θ=2 to 15° range. In this case, if a peak is observed in the azimuthal angle range of -180 to 0°, it is determined that a diffraction peak is observed in the 2θ=2 to 15° range. For example, if a diffraction peak is observed at 2θ=6.8°, when linearizing in the azimuthal direction in the 2θ=6.0 to 7.0° range, if a peak is observed in the azimuthal angle range of -180 to 0°, it can be determined that a diffraction peak is observed in the 2θ=2 to 15° range.

[0069] As a sample to be used for the wide-angle X-ray diffraction, a resin composition in the form of a film, which will be described later, can be used as is. Furthermore, when the film of the resin composition is laminated with another substrate, if the resin composition layer can be peeled off, the resin composition layer is peeled off and measurement is performed. If peeling is not possible, the resin composition layer can be measured while still laminated with the other substrate. During measurement, the thickness of the resin composition layer (film) is preferably 30 μm or more, and if the film is not thick enough, a film may be laminated.

[0070] <Film containing resin composition> The film containing the resin composition of the present invention is obtained by forming a film from a composition containing the resin composition, and preferably from the resin composition.

[0071] Examples of methods for producing the film include a method using a solution (coating liquid) of a composition containing a resin composition, and a method of melt-molding a pellet-shaped composition containing the resin composition of the present invention using an extruder. Among these, a method using a solution (coating liquid) of a composition containing a resin composition is preferred. When using the coating liquid, the solid content is usually 0.5 to 30% by weight, preferably 5 to 20% by weight.

[0072] The coating liquid can be prepared, for example, by adding all components to a solvent at once and mixing them, or by dissolving some components in a solvent and adding other components to the solution and mixing them. Among these, from the viewpoint of workability, the method of adding other components to a solution in which a hydrophilic resin is dissolved in a solvent and mixing them is preferred. In addition, in the method for obtaining the metal compound described above, it is also preferable to dissolve a hydrophilic resin in a solvent when reacting the metal-containing compound, which is particularly preferable in terms of workability when obtaining the metal compound by the method (II) described above. As the solvent, the solvents exemplified for the metal compounds can be used.

[0073] As the film-forming method, known methods can be used, such as a melt extrusion method, an endless belt method, a drum method, a casting method such as a coating method, etc. Among these, the casting method is preferred, and the coating method is particularly preferred.

[0074] Examples of the coating method include known methods such as bar coating, roll coating, die coating, gravure coating, comma coating, and screen printing.

[0075] After coating, a film made of the resin composition can be obtained by drying, for example, by heat treatment at 60 to 105° C. for 0.5 to 10 minutes. Furthermore, the film may be subjected to a stretching operation such as uniaxial stretching or biaxial stretching, if necessary.

[0076] The film may be a single-layer film or a multilayer structure. The multilayer structure preferably has at least one layer made of the film. The multilayer structure may be formed by laminating the film or by laminating another base resin.

[0077] The thickness of the film is usually 1 to 200 μm, preferably 1 to 100 μm, and particularly preferably 1 to 50 μm. When the formed film has a multilayer structure, the total thickness of the film is defined as the total thickness of all films made of the resin composition.

[0078] Examples of the base resin include polyethylene-based resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene-based resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin-based resins such as polybutene, polypentene, and polycyclic olefin-based resins (polymers having a cyclic olefin structure in at least one of the main chain and side chain); and polyolefins obtained by dissolving these polyolefins in an unsaturated carboxylic acid or Examples of the base resin include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins graft-modified with esters of the base resin; ionomers; ethylene-vinyl acetate copolymers; ethylene-acrylic acid copolymers; ethylene-acrylic acid ester copolymers; polyester resins; polyamide resins (including copolymerized polyamides); polyvinyl chloride; polyvinylidene chloride; acrylic resins; polystyrene; vinyl ester resins; polyester elastomers; polyurethane elastomers; polystyrene elastomers; halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene; and aromatic or aliphatic polyketones. These may be used alone or in combination of two or more. These base resins may also be subjected to surface treatments such as corona treatment.

[0079] A film containing the resin composition of the present invention has excellent gas barrier properties under high humidity conditions, and is preferably left standing under high humidity conditions to obtain a film with even more excellent gas barrier properties, particularly oxygen barrier properties, under high humidity conditions. The mechanism by which this effect is obtained is unclear, but it is presumed that the leaving under high humidity conditions plasticizes the hydrophilic resin molecules, and the metal compounds dispersed in the film interact with the hydrophilic resin or localize on the surface of the film.

[0080] In the present invention, "under high humidity" means 20±5°C and 90±10% RH. The standing time is usually 70 hours or more, preferably 100 hours or more, and more preferably 150 hours or more, and the upper limit of the standing time is usually 1,000 hours.

[0081] The oxygen permeability of the film made of the resin composition is 80cc·3μm / m 2 ·day·atm or less is preferable, and 70cc·3μm / m 2 ·day·atm or less is more preferable, and 55cc·3μm / m 2 ·day·atm or less is more preferable, and 40cc·3μm / m 2 ·day·atm or less is more preferable, and 35cc·3μm / m 2 ·day·atm or less is more preferable, and 30cc·3μm / m 2 ·day·atm or less is more preferable, and 25cc·3μm / m 2 It is particularly preferable that the oxygen permeability is 0 cc·day·atm or less. The oxygen permeability is measured in an environment of 23°C and 80% RH, and the lower limit of the oxygen permeability is usually 0 cc·3 μm / m 2 ·day·atm. The oxygen permeability can be determined by an oxygen permeability measuring device.

[0082] Films containing the resin composition of the present invention have extremely excellent transparency, far superior to films containing inorganic layered compounds or fillers. Specifically, films containing the resin composition of the present invention preferably have a haze of 1% or less, more preferably 0.6% or less, even more preferably 0.3% or less, and particularly preferably 0.2% or less. The haze is a haze value measured in accordance with JIS K7361-1. For example, ten 50 mm x 50 mm test pieces are cut from the film and measured using a haze meter (NDH-4000 manufactured by Nippon Denshoku Industries Co., Ltd.), and the average value of the ten pieces is taken as the haze (%).

[0083] The resin composition of the present invention and the film made of the resin composition are useful as packaging materials, and can be particularly preferably used as packaging materials for foods, pharmaceuticals, and the like.

Examples

[0084] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following, "parts" means on a weight basis.

[0085] Prior to the examples, the following hydrophilic resins were prepared.

[0086] 〔Hydrophilic resin〕 [PVA-based resin] ·PVA (unmodified PVA resin, average degree of polymerization 300, average saponification degree 99 mol%)

[0087] Also, the synthesis of the metal compound was carried out according to the following procedure.

[0088] <Synthesis of Zn-containing layered compound> The synthesis of the Zn-containing layered compound was carried out according to the method described in Inorg. Chem. 2013, 52, 95 - 102. Specifically, while stirring 900 parts of a 1.5 mol / L aqueous sodium hydroxide solution at 27°C, 900 parts of a 1.5 mol / L aqueous solution of zinc acetate dihydrate (manufactured by Fujifilm Wako Pure Chemical Corporation) was added thereto, and the mixture was stirred at 27°C for 2 hours to react. After the reaction, the precipitated white precipitate was filtered off by vacuum filtration. Then, the obtained white solid and 750 parts of water were stirred and filtered again to wash the white solid. This washing operation was carried out a total of 3 times while replacing the water. Finally, the white solid obtained by filtration was dried at 60°C overnight (10 hours) under normal pressure to obtain a Zn-containing layered compound.

[0089] <Identification of the synthesized Zn-containing layered compound> The above Zn-containing layered compound was measured by solid NMR and wide-angle X-ray diffraction to identify the Zn-containing layered compound.

[0090] [Solid state NMR ( 13 C-CP / MS) measurement〕 The Zn-containing layered compound was packed into a zirconia rotor with a diameter of 4 mm, and sealed with a polyethylene drive tip to prepare a measurement sample. 1 H:400MHz, 13 Measurements were carried out using a CP / MAS probe (C: 100 MHz, manufactured by Bruker Japan). The measurement conditions were rotation at 5000 Hz, 90° pulse width 45 μs, contact time 2 ms, number of integrations 485, acquisition time 50 ms, and delay time 5 seconds.

[0091] [Wide-angle X-ray diffraction (XRD) measurement] The Zn-containing layered compound was subjected to wide-angle X-ray diffraction (XRD) measurement under the following conditions. [Measurement conditions] Equipment used: D8 DISCOVER (manufactured by Bruker Japan) Voltage: 50kV Current: 100mA Camera length: 150mm Measurement method: Reflection method Accumulation time: 20 minutes As a result of the measurement, peaks were mainly detected at 2θ=6.8°, 13.5°, and 20.2°.

[0092] The solid-state NMR and wide-angle X-ray diffraction measurements showed that the obtained Zn-containing layered compound was identical to that described in Inorg. Chem. 2013, 52, 95-102, and therefore the obtained Zn-containing layered compound was identified as [Zn5(OH)8(CH3CO2)2·2H2O].

[0093] Furthermore, when the Zn-containing layered compound [Zn5(OH)8(CH3CO2)2·2H2O] was measured by wide-angle X-ray diffraction, the interlayer distance was calculated using the Brag equation based on the diffraction position at 2θ=6.8°, where the strongest peak intensity was found. As a result, the Zn-containing layered compound [Zn5(OH)8(CH3CO2)2·2H2O] was found to be a layered compound with an interlayer distance of 1.3 nm.

[0094] Example 1 100 parts of PVA was added to 900 parts of water, and the mixture was heated and stirred at 90°C for 1 hour to completely dissolve the PVA. This solution was allowed to cool to 60°C, and 0.5 parts of the Zn-containing layered compound obtained above, calculated as a metal, was added to 100 parts of PVA. The mixture was stirred at 60°C for 1 hour to prepare a resin composition (coating solution). The resulting coating solution was applied to the corona-treated surface of a 38 μm-thick PET substrate using a wire bar #18 and dried at 80°C for 5 minutes, yielding a two-layer film in which a 3 μm-thick film layer was laminated on the PET substrate. The resulting film was left to stand for 200 hours under humidity conditions of 23°C and 80% RH.

[0095] <Example 2> A film was prepared in the same manner as in Example 1 under the same humidity conditions, except that the amount of Zn-containing layered compound added was changed to 1 part in terms of metal per 100 parts of PVA.

[0096] Example 3 A film was prepared in the same manner as in Example 1 under the same humidity conditions, except that the amount of Zn-containing layered compound added was changed to 3 parts in terms of metal per 100 parts of PVA.

[0097] Example 4 A film was prepared in the same manner as in Example 1 under the same humidity conditions, except that the amount of Zn-containing layered compound added was changed to 5 parts in terms of metal per 100 parts of PVA.

[0098] <Comparative Example 1> A film was prepared in the same manner as in Example 1, except that the Zn-containing layered compound was not added, and the film was prepared under the same humidity conditioning conditions.

[0099] <Comparative Example 2> A film was prepared in the same manner as in Example 1 and prepared under the same humidity control conditions, except that in Example 1, zinc oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added in an amount of 1 part in terms of metal per 100 parts of PVA instead of the Zn-containing layered compound.

[0100] <Comparative Example 3> A film was prepared in the same manner as in Example 1 and under the same humidity control conditions, except that in Example 1, 1 part of zinc chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added in metal equivalent to 100 parts of PVA instead of the Zn-containing layered compound.

[0101] The wide-angle X-ray diffraction and oxygen barrier properties were measured under the following conditions using the films obtained above in Examples 1 to 4 and Comparative Examples 1 to 3. The results are shown in Table 1 below.

[0102] [Wide-angle X-ray diffraction (XRD) measurement of film] The resin composition film obtained above was peeled off from the PET film and laminated to a thickness of 30 μm or more to prepare a sample. Wide-angle X-ray diffraction measurement of this sample was carried out under the following conditions. [Measurement conditions] Equipment used: D8 DISCOVER (manufactured by Bruker Japan) Detector: 2D detector VANTEC-500 (manufactured by Bruker Japan) Voltage: 50kV Current: 100mA Camera length: 100mm Measurement method: Reflection method Accumulation time: 30 minutes Wavelength: CuKα line (Kα1 and Kα2 are not separated) Detector position: 2θ=10° X-ray incident angle: θ=0.3° Conditions for linearization in the 2θ direction: 2θ = 0 to 35°, azimuth angle (chi) = -95 to -85°. Linearization in the azimuth angle direction: 2θ = 6.0 to 7.0°, azimuth angle (chi) = -180 to 0°. After X-ray diffraction measurement, the obtained diffraction image was linearized in the azimuth angle direction in the range of -180 to 0° in the range of 2θ = 6.0 to 7.0° to confirm the azimuth angle dependence of the diffraction intensity. If a diffraction peak was observed at an azimuth angle of -90°, it was determined that the resin composition had a diffraction peak in the range of 2θ = 6.0 to 7.0°.

[0103] [Oxygen barrier properties] The oxygen permeability of the obtained resin composition film was measured under conditions of 23°C and 80% RH using an oxygen permeability measuring device (OX-TRAN100A, manufactured by MOCON).

[0104] [Table 1]

[0105] As can be seen from Table 1 above, Examples 1 to 4, which contain a hydrophilic resin and a metal compound satisfying general formula (1), were excellent in oxygen barrier properties under high humidity conditions. On the other hand, Comparative Examples 1 to 3, which did not contain a metal compound satisfying the general formula (1), all had poor oxygen barrier properties. [Industrial Applicability]

[0106] The resin composition of the present invention is useful as a packaging material, particularly as a packaging material for foods, medicines, etc., because it has excellent gas barrier properties, particularly oxygen barrier properties, under high humidity conditions.

Claims

1. A resin composition comprising a hydrophilic resin and a metal compound, wherein the metal compound satisfies the following general formula (1), the hydrophilic resin is a polyvinyl alcohol-based resin, the metal compound is a metal layer compound, and the metal species is at least one selected from the group consisting of Ni, Co, and Zn: M a (OH) b A n- (2a-b) / n ・・・(1) (The above M represents a metal species, and A represents an anionic ligand other than a hydroxy ligand having an n-valence. However, O (oxo ligand) is excluded as A. n is an integer of 1 or more, a and b are numbers greater than 0, and a / b=0.1 to 10 is satisfied.

2. 2. The resin composition according to claim 1, wherein the content of said metal compound in terms of metal is 0.01 to 10 parts by weight per 100 parts by weight of the hydrophilic resin.

3. A film comprising the resin composition according to claim 1 or 2.

4. The oxygen permeability of the film under the conditions of 23°C and 80% RH is 80cc.3µm / m 2 4. The film according to claim 3, wherein the film has a viscosity of 0.5 sq. day atm or less.

5. A multilayer structure comprising at least one layer made of the film according to claim 3 or 4.

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