Gas barrier laminate, packaging body and packaged article

Abstract

To provide a gas barrier laminate capable of maintaining high oxygen barrier property after moist heat treatment, and suppressed in reduction of oxygen barrier property caused by infiltration of sulfur due to moist heat treatment even in the case that a content contains sulfur.SOLUTION: A gas barrier laminate comprises a base material, an inorganic oxide-containing inorganic vapor-deposited layer, and a coating layer in this order. The gas barrier laminate is such that: the coating layer comprises a single layer of a plurality of layers; the coating layer contains a carboxyl group-containing polymer, and at least one kind of polyvalent metal-containing particles; the total value of fluorescent X-ray intensity of metal elements contained in the polyvalent metal-containing particles is 3.0 kcps or more and 8.0 kcps or less; and an absorbance X of the gas barrier laminate after hot water treatment for 30 minutes at 130°C using 0.3 mass% of an L-cysteine aqueous solution, calculated by subtracting an absorbance X2 of a wavelength of 500 nm from an absorbance X1 of a wavelength of 350 nm measured by using an ultraviolet visible spectrophotometer satisfies formula: X=X1-X2≥0.02(abs).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas barrier laminate, a package, and a packaged article. [Background technology]

[0002] Packaging materials used for packaging foods, pharmaceuticals, cosmetics, pesticides, industrial products, and the like are required to prevent deterioration of the contents. For example, food packaging materials are required to have a deterioration prevention function that suppresses oxidation and deterioration of proteins, oils, and fats, and furthermore, preserves flavor and freshness. Such deterioration of the contents is caused by oxygen and water vapor that permeate the packaging material, or other gases that react with the contents. For this reason, packaging materials that are impermeable to gases such as oxygen and water vapor (gas barrier properties) have been developed.

[0003] For example, Patent Documents 1 to 3 disclose laminates that have a coating layer containing a carboxylic acid polymer and a polyvalent metal compound, and that have gas barrier properties imparted by crosslinking at least a portion of the -COO- groups contained in the carboxylic acid polymer with polyvalent metal ions. Such gas barrier laminates have excellent gas barrier properties even in high-humidity atmospheres, and can therefore also be used in packaging applications that undergo moist heat treatments such as boiling and retorting. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5278802 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-193509 [Patent Document 3] International Publication No. 2016-158444 Summary of the Invention [Problem to be solved by the invention]

[0005] When a package is filled with food or other contents and subjected to a moist heat treatment such as retort treatment or boiling treatment, substances generated from the contents may permeate the packaging material and adversely affect the gas barrier properties. For example, if the contents filled in the package contain sulfur, sulfur components are generated from the contents by the moist heat treatment. This sulfur permeates the packaging material, causing a problem of particularly deteriorating the oxygen barrier properties.

[0006] The present invention aims to provide a gas barrier laminate that can maintain high oxygen barrier properties after moist heat treatment such as retort treatment and boiling treatment, and that, even when the contents contain sulfur, is inhibited from decreasing in oxygen barrier properties due to penetration of sulfur by moist heat treatment, as well as a package and packaged article that include the same. [Means for solving the problem]

[0007] It has been found that the problem of the deterioration of oxygen barrier property described above is caused by sulfur generated from the contents during moist heat treatment such as retort treatment reacting with and bonding to polyvalent metal ions of a polyvalent metal compound bonded to a carboxy group-containing polymer, resulting in the destruction of the crosslinked structure. An embodiment of the present invention prevents sulfur generated from the contents by moist heat treatment from bonding to polyvalent metal ions of a polyvalent metal compound bonded to a carboxy group-containing polymer, thereby suppressing the destruction of the crosslinked structure by sulfur and maintaining high oxygen barrier property.

[0008] That is, according to a first aspect of the present invention, there is provided a gas barrier laminate comprising, in this order, a base material, an inorganic vapor deposition layer containing an inorganic oxide, and a coating layer, the coating layer consisting of a single layer or multiple layers, the coating layer containing a carboxy group-containing polymer and at least one type of polyvalent metal-containing particle, the total fluorescent X-ray intensity of the metal elements contained in the polyvalent metal-containing particles being 3.0 kcps or more and 8.0 kcps or less, and the gas barrier laminate after hot water treatment with a 0.3 mass % L-cysteine ​​aqueous solution at 130°C for 30 minutes has an absorbance X, obtained by subtracting the absorbance X2 at a wavelength of 500 nm from the absorbance X1 at a wavelength of 350 nm, as measured using an ultraviolet-visible spectrophotometer, satisfying the following formula (1): X = X1 - X2 ≥ 0.02(abs) (1)

[0009] According to a second aspect of the present invention, there is provided a package including the laminate according to the first aspect.

[0010] According to a third aspect of the present invention, there is provided a packaged article including the package according to the second aspect and contents contained therein. [Effects of the Invention]

[0011] According to the present invention, there are provided a gas barrier laminate that can maintain high oxygen barrier properties after moist heat treatment such as retort treatment and boiling treatment, and further, that is inhibited from experiencing a decrease in oxygen barrier properties due to penetration of sulfur by moist heat treatment, even when the contents contain sulfur, as well as a package and a packaged article that include the same. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a laminate according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a laminate according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are more specific embodiments of any of the above aspects. In this disclosure, the expression "AA on BB" is used regardless of the direction of gravity. The state specified by the expression "AA on BB" includes a state in which AA is in contact with BB. The expression "AA on BB" does not exclude the presence of one or more other components between AA and BB.

[0014] <Gas barrier laminate> FIG. 1 is a cross-sectional view that schematically shows a gas barrier laminate according to one embodiment of the present invention. The gas barrier laminate 10 shown in Fig. 1 comprises, in this order, a substrate 1, an inorganic vapor deposition layer 2 containing an inorganic oxide, and a coating layer 3. The coating layer 3 is a single layer or a laminate unit consisting of multiple layers (not shown), and contains a carboxyl group-containing polymer (a) and at least one type of polyvalent metal-containing particle (b).

[0015] In the gas barrier laminate 10, the total fluorescent X-ray intensity of the metal elements contained in the polyvalent metal-containing particles (b) contained in the coating layer 3 is 3.0 kcps or more and 8.0 kcps or less, and after hot water treatment using a 0.3 mass % L-cysteine ​​aqueous solution at 130°C for 30 minutes, the absorbance X obtained by subtracting the absorbance X2 at a wavelength of 500 nm from the absorbance X1 at a wavelength of 350 nm measured using an ultraviolet-visible spectrophotometer satisfies the following formula (1): X = X1 - X2 ≥ 0.02(abs) (1)

[0016] Polyvalent metal ions generated from the polyvalent metal-containing particles contained in the coating layer 3 react with the carboxyl group-containing polymer (a). In this case, a crosslinked structure is formed in which the carboxyl group-containing polymers (a) are ionically crosslinked to one another via the polyvalent metal ions. This improves the oxygen barrier property of the coating layer 3, allowing the gas barrier laminate 10 to exhibit excellent oxygen barrier property. Here, if sulfur generated from the contents by moist heat treatment such as retort treatment or boiling treatment permeates the packaging material, the polyvalent metal ions constituting the crosslinked structure of the coating layer 3 react with sulfur ions. In this case, the crosslinked structure is destroyed in conventional gas barrier laminates, resulting in a problem of reduced oxygen barrier property.

[0017] In contrast, in the gas barrier laminate 10 according to this embodiment, as described above, the total fluorescent X-ray intensity of the metal elements of the polyvalent metal-containing particles (b) contained in the coating layer 3 is 3.0 kcps or more and 8.0 kcps or less, and the absorbance X measured after the hot water treatment is 0.02 abs or more. When all of these conditions are met, a crosslinked structure of the carboxyl group-containing polymer (a) is formed in the coating layer 3 via the polyvalent metal ions during the wet heat treatment, and excess polyvalent metal ions not involved in the crosslinked structure are present.

[0018] Here, the term "excessive amount of polyvalent metal ions" refers to an amount of polyvalent metal ions in excess of the amount of polyvalent metal ions required to form a crosslinked structure with the carboxy group-containing polymer (a). Therefore, if sulfur generated from the contents permeates the gas barrier laminate, which is a packaging material, during the moist heat treatment, the excess polyvalent metal ions present in the coating layer 3 will chemically react with the sulfur. As a result, it is possible to prevent sulfur from destroying the crosslinked structure.

[0019] Thus, even when the contents contain sulfur, the gas barrier laminate 10 according to this embodiment can suppress the adverse effects of sulfur penetrating into the laminate during moist heat treatment, which destroys the cross-linked structure. Therefore, by using the gas barrier laminate 10 according to this embodiment as a packaging material, high oxygen barrier properties can be maintained after moist heat treatment such as retort treatment and boiling treatment, even when the contents contained in the package contain sulfur, such as sulfur-containing amino acids.

[0020] Here, absorbance X is ultraviolet absorbance (UV absorbance) measured using an ultraviolet-visible spectrophotometer, and corresponds to the value (abs) obtained by subtracting absorbance X2 at a wavelength of 500 nm from absorbance X1 at a wavelength of 350 nm measured for the gas barrier laminate after hot water treatment. The hot water treatment conditions were a 0.3% by mass L-cysteine ​​aqueous solution, retort treatment at 130°C for 30 minutes using a hot water storage method.

[0021] Furthermore, sulfur generated from the contents during moist heat treatment such as retort treatment is accompanied by an unpleasant odor known as retort odor. However, the sulfur chemically reacts with excess polyvalent metal ions present in the coating layer 3 and is retained within the gas barrier laminate, thereby preventing the retort odor from permeating the package.

[0022] Each layer contained in the gas barrier laminate 10 according to this embodiment will be described below. <Coating layer> The coating layer 3 contains a carboxyl group-containing polymer (a) and polyvalent metal-containing particles (b), which will be described in detail below. The coating layer 3 may further contain a surfactant, a silicon-containing compound, and the like.

[0023] As described above, in the gas barrier laminate 10 according to this embodiment, the total fluorescent X-ray intensity of the metal elements of the polyvalent metal-containing particles (b) contained in the coating layer 3 is 3.0 kcps or more and 8.0 kcps or less, and the absorbance X measured after hot water treatment is 0.02 abs or more. When these conditions are met, a crosslinked structure of the carboxyl group-containing polymer (a) is formed in the coating layer 3 via the polyvalent metal ions during the wet heat treatment, and excess polyvalent metal ions that are not involved in this crosslinked structure are present.

[0024] Each element can be quantitatively analyzed by measuring the fluorescent X-ray intensity of each element contained in the coating layer 3. In this embodiment, when the total fluorescent X-ray intensity of the metal elements derived from the polyvalent metal-containing particles contained in the coating layer 3 is 3.0 kcps or more, excellent oxygen barrier properties are exhibited due to the ionic crosslinking structure of the carboxy group-containing polymer (a) formed via the polyvalent metal ions.

[0025] On the other hand, if the total fluorescent X-ray intensity of the metal elements contained in the coating layer 3 exceeds 8.0 kcp, the film strength will be weakened, resulting in a decrease in oxygen barrier properties. When the coating layer 3 contains only one type of polyvalent metal-containing particle (b), the total fluorescent X-ray intensity refers to the fluorescent X-ray intensity of that single particle. When the coating layer 3 contains only one type of zinc compound as the polyvalent metal-containing particle (b), the fluorescent X-ray intensity is preferably 4.0 kcps or more.

[0026] In the gas barrier laminate 10, the more polyvalent metal-containing particles (b) that are not bonded to the carboxyl group-containing polymer (a) there are, the higher the UV absorbance tends to be. In this embodiment, when the absorbance X is 0.02 or higher, excess polyvalent metal ions that are not bonded to the carboxyl group-containing polymer (a) may be present in the coating layer 3. As described above, when sulfur generated from the contents penetrates into the coating layer 3 by the moist heat treatment, the sulfur chemically reacts with the excess polyvalent metal ions. As a result, destruction of the crosslinked structure by sulfur is suppressed, and high oxygen barrier properties can be maintained.

[0027] In this embodiment, the absorbance X of the gas barrier laminate 10 is 0.02 or more. On the other hand, the upper limit of the absorbance X of the gas barrier laminate 10 is not particularly limited, as long as it is lower than the absorbance before the hot water treatment. In one example, the upper limit of the absorbance X can be appropriately set from the perspective of the crosslinking rate of -COO- groups contained in the carboxy group-containing polymer (a), and may be, for example, 0.4 or less.

[0028] The coating layer 3 may be a single layer or a laminate unit consisting of multiple layers. When the coating layer 3 consists of multiple layers, the carboxy group-containing polymer (a) and the polyvalent metal-containing particles (b) may be contained in the same layer or in different layers.

[0029] An example of a case where the coating layer 3 is composed of multiple layers is one in which the coating layer 3 includes a laminate unit in which a first coating layer containing a carboxyl group-containing polymer (a) and a second coating layer containing polyvalent metal-containing particles (b) are adjacent to each other. According to one example, it is preferable that the first coating layer and the second coating layer are laminated in this order from the inorganic vapor deposition layer 2 side.

[0030] In this case, at least a portion of the polyvalent metal ions generated from the polyvalent metal-containing particles (b) contained in the second coating layer diffuse into the first coating layer during the moist heat treatment. If the contents contain sulfur, some of the sulfur generated from the contents during the moist heat treatment chemically reacts with the polyvalent metal-containing particles (b) in the second coating layer, but the remaining sulfur may reach the first coating layer. The gas barrier laminate 10 according to this embodiment satisfies all of the above-mentioned conditions regarding UV absorbance X and fluorescent X-ray intensity. Therefore, of the polyvalent metal ions that diffuse into the first coating layer during the moist heat treatment, a necessary amount of polyvalent metal ions form a crosslinked structure, and excess polyvalent metal ions chemically react with sulfur that reaches the first coating layer, preventing sulfur from destroying the crosslinked structure.

[0031] The first coating layer may further contain polyvalent metal-containing particles (b). In this case, the polyvalent metal-containing particles (b) contained in the first coating layer may be the same as or different from the polyvalent metal-containing particles (b) contained in the second coating layer. Specific examples of the polyvalent metal-containing particles (b) contained in the first coating layer and the second coating layer can be appropriately selected from the specific examples described below. Examples include zinc compounds and calcium compounds.

[0032] [Carboxy group-containing polymer (a)] The carboxyl group-containing polymer (a) contained in the coating layer 3 is a polymer having two or more carboxyl groups in its molecule, and may be referred to below as a "polycarboxylic acid polymer." As described above, the carboxyl group-containing polymer (a) forms ionic crosslinks with metal ions derived from the polyvalent metal-containing particles (b) described below in the coating layer 3, thereby exhibiting excellent gas barrier properties. Representative examples of the carboxyl group-containing polymer (a) include a homopolymer of a carboxyl group-containing unsaturated monomer, a copolymer of two or more types of carboxyl group-containing unsaturated monomers, a copolymer of a carboxyl group-containing unsaturated monomer and another polymerizable monomer, and a polysaccharide containing a carboxyl group in its molecule (also referred to as a "carboxyl group-containing polysaccharide" or "acidic polysaccharide").

[0033] The carboxy group includes not only a free carboxy group but also an acid anhydride group (specifically, a dicarboxylic acid anhydride group). The acid anhydride group may be partially ring-opened to form a carboxy group. A portion of the carboxy group may be neutralized with an alkali. In this case, the degree of neutralization is preferably 20% or less.

[0034] Here, the "degree of neutralization" is a value obtained by the following method. That is, the carboxyl groups can be partially neutralized by adding an alkali (ft) to the carboxyl group-containing polymer (a). In this case, the ratio of the number of moles (ft) of the alkali (f) to the number of moles (at) of the carboxyl groups contained in the carboxyl group-containing polymer (a) is the degree of neutralization.

[0035] In addition, a graft polymer obtained by graft polymerizing a carboxyl-containing unsaturated monomer onto a polymer not containing a carboxyl group, such as a polyolefin, can also be used as the carboxyl-containing polymer (a). A polymer obtained by hydrolyzing a polymer having a hydrolyzable ester group such as an alkoxycarbonyl group (e.g., a methoxycarbonyl group) to convert it into a carboxyl group can also be used.

[0036] The carboxyl group-containing unsaturated monomer is preferably an α,β-monoethylenically unsaturated carboxylic acid. Therefore, the carboxyl group-containing polymer (a) includes a homopolymer of an α,β-monoethylenically unsaturated carboxylic acid, a copolymer of two or more α,β-monoethylenically unsaturated carboxylic acids, and a copolymer of an α,β-monoethylenically unsaturated carboxylic acid with another polymerizable monomer. A typical example of the other polymerizable monomer is an ethylenically unsaturated monomer.

[0037] Examples of α,β-monoethylenically unsaturated carboxylic acids include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; unsaturated dicarboxylic anhydrides such as maleic anhydride and itaconic anhydride; and mixtures of two or more of these. Among these, at least one α,β-monoethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid is preferred, and at least one α,β-monoethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, and maleic acid is more preferred.

[0038] Other polymerizable monomers copolymerizable with α,β-monoethylenically unsaturated carboxylic acids, particularly ethylenically unsaturated monomers, include, for example, ethylene; α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene; saturated carboxylic acid vinyl esters such as vinyl acetate; acrylic acid alkyl esters such as methyl acrylate and ethyl acrylate; methacrylic acid alkyl esters such as methyl methacrylate and ethyl methacrylate; chlorine-containing vinyl monomers such as vinyl chloride and vinylidene chloride; fluorine-containing vinyl monomers such as vinyl fluoride and vinylidene fluoride; unsaturated nitriles such as acrylonitrile and methacrylonitrile; aromatic vinyl monomers such as styrene and α-methylstyrene; and itaconic acid alkyl esters. These ethylenically unsaturated monomers can be used alone or in combination of two or more. Furthermore, when the carboxy group-containing polymer is a copolymer of an α,β-monoethylenically unsaturated carboxylic acid and a saturated carboxylic acid vinyl ester such as vinyl acetate, a copolymer obtained by saponifying this copolymer to convert the saturated carboxylic acid vinyl ester units into vinyl alcohol units can also be used.

[0039] Examples of carboxyl group-containing polysaccharides include acidic polysaccharides having a carboxyl group in the molecule, such as alginic acid, carboxymethylcellulose, and pectin. These acidic polysaccharides can be used alone or in combination of two or more. Acidic polysaccharides can also be used in combination with (co)polymers of α,β-monoethylenically unsaturated carboxylic acids.

[0040] When the carboxy group-containing polymer (a) is a copolymer of an α,β-monoethylenically unsaturated carboxylic acid and another ethylenically unsaturated monomer, from the viewpoint of the gas barrier property, hot water resistance, and water vapor resistance of the resulting film, the proportion of the number of moles of the α,β-monoethylenically unsaturated carboxylic acid monomer to the total number of moles of those monomers in the copolymer is preferably 60 mol % or more, more preferably 80 mol % or more, and particularly preferably 90 mol % or more.

[0041] The carboxyl group-containing polymer (a) is preferably a homopolymer or copolymer obtained by polymerization of only α,β-monoethylenically unsaturated carboxylic acid, since it is easy to obtain a film that has excellent gas barrier properties, moisture resistance, water resistance, hot water resistance, and water vapor resistance, and that also has excellent gas barrier properties under high humidity conditions. When the carboxyl group-containing polymer (a) is a (co)polymer consisting of only α,β-monoethylenically unsaturated carboxylic acid, preferred examples include homopolymers, copolymers, and mixtures of two or more thereof obtained by polymerization of at least one α,β-monoethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. Among these, homopolymers and copolymers of at least one α,β-monoethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, and maleic acid are more preferred.

[0042] As the carboxyl group-containing polymer (a), polyacrylic acid, polymethacrylic acid, polymaleic acid, and a mixture of two or more thereof are particularly preferred. As the acidic polysaccharide, alginic acid is preferred. Among these, polyacrylic acid is particularly preferred because it is relatively easy to obtain and a film with excellent physical properties can be easily obtained.

[0043] The number average molecular weight of the carboxy group-containing polymer (a) is not particularly limited, but from the viewpoint of film formability and film physical properties, the number average molecular weight is preferably in the range of 2,000 to 10,000,000, more preferably in the range of 5,000 to 1,000,000, and even more preferably in the range of 10,000 to 500,000.

[0044] Here, the "number average molecular weight" is a value obtained by measurement using gel permeation chromatography (GPC). In GPC measurement, the number average molecular weight of a polymer is generally measured in terms of standard polystyrene.

[0045] [Polyvalent metal-containing particles (b)] The polyvalent metal-containing particles (b) contained in the coating layer 3 are preferably particles containing one or more polyvalent metals whose metal ions have a valence of 2 or more. The polyvalent metal-containing particles (b) may be particles made of a polyvalent metal whose metal ions have a valence of 2 or more, particles made of a compound of a polyvalent metal whose metal ions have a valence of 2 or more, or a mixture thereof.

[0046] Specific examples of polyvalent metals include, but are not limited to, metals in Group 2A of the short periodic table, such as beryllium, magnesium, and calcium; transition metals, such as titanium, zirconium, chromium, manganese, iron, cobalt, nickel, copper, and zinc; and aluminum.

[0047] The polyvalent metal is preferably a divalent metal, and the polyvalent metal preferably forms a compound.

[0048] Specific examples of polyvalent metal compounds include, but are not limited to, oxides, hydroxides, carbonates, organic acid salts, and inorganic acid salts of polyvalent metals. Examples of organic acid salts include, but are not limited to, acetates, oxalates, citrates, lactates, phosphates, phosphites, hypophosphites, stearates, and monoethylenically unsaturated carboxylates. Examples of inorganic acid salts include, but are not limited to, chlorides, sulfates, and nitrates. Alkyl alkoxides of polyvalent metals can also be used as polyvalent metal compounds. These polyvalent metal compounds can be used alone or in combination of two or more.

[0049] Among polyvalent metal compounds, from the viewpoint of the gas barrier properties of the gas barrier laminate 10, compounds of beryllium, magnesium, calcium, copper, cobalt, nickel, zinc, aluminum, and zirconium are preferred, and compounds of divalent metals such as beryllium, magnesium, calcium, copper, zinc, cobalt, and nickel are more preferred.

[0050] Preferred divalent metal compounds include, but are not limited to, oxides such as zinc oxide, magnesium oxide, copper oxide, nickel oxide, and cobalt oxide; carbonates such as calcium carbonate; organic acid salts such as calcium lactate, zinc lactate, and calcium acrylate; and alkoxides such as magnesium methoxide. For example, the coating layer 3 preferably contains at least one of a zinc compound and a calcium compound.

[0051] The polyvalent metal or polyvalent metal compound is used as particles. As the polyvalent metal-containing particles (b), those having an average particle diameter in the coating liquid of 10 nm to 10 μm (or 10,000 nm) are preferably used from the viewpoints of dispersion stability of the coating liquid (hereinafter referred to as the "coating liquid for forming a coating layer" or simply the "coating liquid") used to form the coating layer 3, which will be described later, and the gas barrier properties of the gas barrier laminate 10. The average particle diameter of the polyvalent metal-containing particles (b) in the coating liquid is more preferably in the range of 12 nm to 1 μm (or 1,000 nm), even more preferably in the range of 15 nm to 500 nm, and particularly preferably in the range of 15 nm to 50 nm.

[0052] If the average particle size of the polyvalent metal-containing particles (b) is too large, the coating layer 3 tends to have insufficient uniformity in thickness, surface flatness, and ionic crosslinking reactivity with the carboxyl group-containing polymer (a). If the average particle size of the polyvalent metal-containing particles (b) is too small, the ionic crosslinking reaction with the carboxyl group-containing polymer (a) may proceed prematurely. Furthermore, if the average particle size of the polyvalent metal-containing particles (b) is too small, it may be difficult to uniformly disperse the particles in the coating liquid.

[0053] The average particle size of the polyvalent metal-containing particles (b) can be measured by measuring and counting using a scanning electron microscope or a transmission electron microscope when the sample is a dry solid. The average particle size of the polyvalent metal-containing particles (b) in the coating liquid can be measured by a light scattering method (Reference: "Fine Particle Engineering System", Vol. I, pp. 362-365, Fuji Techno System (2001)).

[0054] The polyvalent metal-containing particles in the coating liquid exist as primary particles, secondary particles, or a mixture thereof, but in most cases, it is presumed that they exist as secondary particles in view of the average particle diameter.

[0055] [Surfactant (c)] The coating layer 3 contains a surfactant (c) to enhance the dispersibility of the polyvalent metal-containing particles (b). A surfactant is a compound having both a hydrophilic group and a lipophilic group in its molecule. Surfactants include anionic, cationic, and amphoteric ionic surfactants, as well as nonionic surfactants. Any surfactant may be used in the coating layer 3.

[0056] Anionic surfactants include, for example, carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type. Examples of carboxylic acid type anionic surfactants include aliphatic monocarboxylates, polyoxyethylene alkyl ether carboxylates, N-acylsarcosinates, and N-acylglutamates. Examples of sulfonic acid type anionic surfactants include dialkyl sulfosuccinates, alkanesulfonates, alphaolefin sulfonates, linear alkylbenzene sulfonates, alkyl (branched)benzene sulfonates, naphthalene sulfonate-formaldehyde condensates, alkylnaphthalene sulfonates, and N-methyl-N-acyltaurates. Examples of sulfate ester type anionic surfactants include alkyl sulfates, polyoxyethylene alkyl ether sulfates, and fat sulfate esters. Examples of phosphate ester type anionic surfactants include alkyl phosphates, polyoxyethylene alkyl ether phosphates, and polyoxyethylene alkylphenyl ether phosphates.

[0057] Examples of the cationic surfactant (c) include alkylamine salts and quaternary ammonium salts. Examples of alkylamine salt cationic surfactants include monoalkylamine salts, dialkylamine salts, and trialkylamine salts. Examples of quaternary ammonium salt cationic surfactants include alkyltrimethylammonium halide (chloride, bromide, or iodide) salts and alkylbenzalkonium chloride.

[0058] Examples of amphoteric surfactants include carboxybetaine type, 2-alkylimidazoline derivative type, glycine type, and amine oxide type. Examples of carboxybetaine type amphoteric surfactants include alkylbetaine and fatty acid amidopropyl betaine. Examples of 2-alkylimidazoline derivative type amphoteric surfactants include 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine. Examples of glycine type amphoteric surfactants include alkyl or dialkyldiethylenetriaminoacetic acid. Examples of amine oxide type amphoteric surfactants include alkylamine oxide.

[0059] Nonionic surfactants include, for example, ester type, ether type, ester ether type, and alkanolamide type. Ester type nonionic surfactants include, for example, glycerin fatty acid ester, sorbitan fatty acid ester, and sucrose fatty acid ester. Ether type nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and polyoxyethylene polyoxypropylene glycol. Ester ether type nonionic surfactants include, for example, fatty acid polyethylene glycol and fatty acid polyoxyethylene sorbitan. Alkanolamide type nonionic surfactants include, for example, fatty acid alkanolamide.

[0060] Surfactants having a polymer backbone, such as styrene-acrylic acid copolymers, can also be used.

[0061] Among these surfactants, anionic surfactants such as phosphate esters and surfactants having a polymer skeleton such as styrene-acrylic acid copolymers are preferred.

[0062] [Silicon-containing compounds (d)] To enhance peel strength, the coating layer 3 preferably contains a silicon-containing compound (d). The silicon-containing compound (d) is at least one compound selected from the group consisting of a silane coupling agent represented by the following general formula (1), a silane coupling agent represented by the following general formula (2), their hydrolysates, and their condensates. Si(OR1)3Z1…(1) Si(R2)(OR3)2Z2…(2) In general formula (1), R1 may be the same or different and are alkyl groups having 1 to 6 carbon atoms, and Z1 is an organic group containing an epoxy group or an amino group. In general formula (2), R2 is a methyl group, R3 may be the same or different and are alkyl groups having 1 to 6 carbon atoms, and Z2 is an organic group containing an epoxy group or an amino group.

[0063] Silane coupling agents readily undergo hydrolysis and readily undergo condensation reactions in the presence of acid or alkali. Therefore, in the coating layer 3, the silicon-containing compound (d) rarely exists solely in the form of the silane coupling agent represented by general formula (1) or (2), solely in the form of its hydrolysate, or solely in the form of its condensate. That is, in the coating layer 3, the silicon-containing compound (d) is usually present as a mixture of at least one of the silane coupling agent represented by general formula (1) and the silane coupling agent represented by general formula (2), its hydrolysate, and its condensate.

[0064] In general formulas (1) and (2), R1 and R3 may each be an alkyl group having 1 to 6 carbon atoms, and are preferably a methyl group or an ethyl group. Z1 and Z2 may be, for example, an organic group having a glycidyloxy group or an aminoalkyl group.

[0065] Specific examples of the silane coupling agent represented by general formula (1) or (2) include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, aminopropyltrimethoxysilane, and aminopropyltriethoxysilane, with 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropyltrimethoxysilane being preferred. As the silane coupling agent, one type may be used, or two or more types may be used.

[0066] The hydrolysate of the silane coupling agent represented by general formula (1) or (2) may be a partial hydrolysate, a complete hydrolysate, or a mixture thereof.

[0067] The condensates that the coating layer 3 may contain as at least a portion of the silicon-containing compound (d) are two or more of the following: a hydrolysis condensate of a silane coupling agent represented by general formula (1), a hydrolysis condensate of a silane coupling agent represented by general formula (2), and a condensate of a hydrolysis condensate of a silane coupling agent represented by general formula (1) and a hydrolysis condensate of a silane coupling agent represented by general formula (2). These hydrolysis condensates are produced by the following reaction: First, the silane coupling agent is hydrolyzed. As a result, one or more alkoxy groups contained in the silane coupling agent molecule are replaced with hydroxyl groups, resulting in a hydrolysis product. Subsequently, these hydrolysis products are condensed to form a compound in which a silicon atom (Si) is bonded via oxygen. This condensation is repeated to obtain a hydrolysis condensate.

[0068] 〔composition〕 The following describes the composition of the coating layer 3. When the coating layer 3 is a laminate unit made up of multiple layers, the composition of the coating layer 3 referred to here means the composition of the laminate unit.

[0069] The coating layer 3 preferably contains the carboxyl group-containing polymer (a) and the polyvalent metal-containing particles (b) in the following blending ratio. In an embodiment of the present invention, the number of moles of carboxy groups contained in the carboxy group-containing polymer (a) (a t ) the product of the number of moles of the polyvalent metal contained in the polyvalent metal-containing particles (b) and the valence (b t ) ratio ((b t ) / (a t )) (hereinafter also referred to as the equivalent ratio) is preferably 0.4 or more. This ratio is more preferably 0.8 or more, and particularly preferably 1.0 or more. The upper limit of this ratio is usually 15.0 or less. When the coating layer 3 is a single layer, the equivalent ratio (b t ) / (a t ) is preferably 10.0 or less, and more preferably 2.0 or less. If this ratio is too small, the properties of the gas barrier laminate 10, such as gas barrier properties, hot water resistance, and water vapor resistance, tend to decrease.

[0070] The above equivalent ratio can be determined, for example, as follows: An example will be described in which the carboxyl group-containing polymer (a) is polyacrylic acid and the polyvalent metal compound particles (b) are magnesium oxide.

[0071] Polyacrylic acid has a molecular weight of 72 per monomer unit and one carboxy group per monomer molecule. Therefore, the amount of carboxy groups in 100 g of polyacrylic acid is 1.39 moles. An equivalent ratio of 1.0 in a coating solution containing 100 g of polyacrylic acid means that the coating layer 3 contains magnesium oxide in an amount sufficient to neutralize 1.39 moles of carboxy groups. Therefore, to achieve an equivalent ratio of 0.6 in a coating layer 3 containing 100 g of polyacrylic acid, magnesium oxide must be added to the coating layer 3 in an amount sufficient to neutralize 0.834 moles of carboxy groups. The magnesium valence is divalent, and the molecular weight of magnesium oxide is 40. Therefore, to achieve an equivalent ratio of 0.6 in a coating layer 3 containing 100 g of polyacrylic acid, 16.68 g (0.417 moles) of magnesium oxide must be added to the coating layer 3.

[0072] The surfactant (c) is used in an amount sufficient to stably disperse the polyvalent metal-containing particles in the coating liquid, and therefore, the amount of surfactant (c) in the coating liquid is usually 0.0001 to 70% by mass, preferably 0.001 to 60% by mass, and more preferably 0.1 to 50% by mass, in terms of its concentration in the coating liquid for forming a coating layer.

[0073] If surfactant (c) is not added, it becomes difficult to disperse the polyvalent metal-containing particles (b) in the coating solution so that their average particle diameter becomes sufficiently small. As a result, it becomes difficult to obtain a coating solution in which the polyvalent metal-containing particles (b) are uniformly dispersed. In this case, it becomes difficult to obtain a coating layer 3 having a uniform thickness when the coating solution is applied to the inorganic vapor deposition layer 2 and dried.

[0074] From the viewpoint of achieving both high gas barrier properties and transparency in the gas barrier laminate 10, the coating layer 3 preferably contains the silicon-containing compound (d) in an amount such that the molar ratio (dt) / (at) of the number of moles (dt) of the silicon-containing compound (d) to the number of moles (at) of carboxy groups contained in the carboxy group-containing polymer (a) is 0.15% or more and 6.10% or less. Here, (dt) in the molar ratio (dt) / (at) is the number of moles of the silicon-containing compound (d) converted into a silane coupling agent.

[0075] If the amount of silicon-containing compound (d) added is too small, and the molar ratio (dt) / (at) is lower than 0.15%, the peel strength of the gas barrier laminate 10 tends to decrease, which requires careful handling to prevent delamination, leading to reduced productivity.

[0076] From the above viewpoints, the molar ratio (dt) / (at) of the number of moles (dt) of the silicon-containing compound (d) to the number of moles (at) of the carboxyl groups contained in the carboxyl group-containing polymer (a) is preferably 0.3% or more, more preferably 0.46% or more, and particularly preferably 0.61% or more.

[0077] On the other hand, if the amount of silicon-containing compound (d) added is too large and the molar ratio (dt) / (at) exceeds 6.10%, the transparency of the gas barrier laminate 10 tends to decrease. Furthermore, the silicon-containing compound (d) does not have gas barrier properties. Therefore, if the molar ratio (dt) / (at) exceeds 6.10%, not only does the transparency of the laminate decrease, but the gas barrier properties also tend to decrease.

[0078] From the above viewpoints, the molar ratio (dt) / (at) of the number of moles (dt) of the silicon-containing compound (d) to the number of moles (at) of the carboxyl groups contained in the carboxyl group-containing polymer (a) is preferably 4.57% or less, more preferably 3.66% or less, and particularly preferably 2.13% or less.

[0079] From the viewpoint of achieving both transparency and gas barrier properties, the thickness of the coating layer 3 is preferably 230 nm or more and 600 nm or less. Specifically, the thickness of the coating layer 3 here is the thickness measured by the method for measuring the thickness of a coating layer described below. Furthermore, when the coating layer 3 is made up of multiple layers, the thickness of the coating layer 3 referred to here means the total thickness. The thickness of the coating layer 3 is more preferably 250 nm or more and 500 nm or less, and even more preferably 300 nm or more and 450 nm or less.

[0080] <Inorganic vapor deposition layer> The gas barrier laminate 10 according to this embodiment includes an inorganic vapor deposition layer 2 between the substrate 1 and the coating layer 3. This further enhances the gas barrier properties of the gas barrier laminate 10 including the coating layer 3, making it possible to achieve both transparency and high gas barrier properties.

[0081] The inorganic vapor deposition layer 2 contains an inorganic oxide. Examples of inorganic oxides include aluminum oxide, silicon oxide, magnesium oxide, and tin oxide. Among these, aluminum oxide, silicon oxide, magnesium oxide, or a mixture of two or more of these is preferred from the viewpoint of achieving both transparency and gas barrier properties.

[0082] The thickness of the inorganic vapor deposition layer 2 may be, for example, in the range of 5 to 100 nm, or may be in the range of 10 to 50 nm. A thickness of 5 nm or more is preferable from the viewpoint of forming a uniform thin film. A uniform thin film serving as a gas barrier material can adequately perform the functions required of a gas barrier material. A thickness of 100 nm or less is preferable from the viewpoint of the flexibility of the thin film. If the gas barrier material has poor flexibility, cracks may occur due to external factors such as bending or pulling.

[0083] <Base material> There are no particular limitations on the substrate 1 included in the gas barrier laminate 10 according to this embodiment, and various types can be used. There are no particular limitations on the material that constitutes the substrate 1, and various types can be used, such as plastic or paper.

[0084] The substrate 1 may be a single layer made of a single material, or may be a multi-layer made of multiple materials. An example of a multi-layer substrate is one in which a plastic film is laminated onto paper.

[0085] Of the above materials, plastic is preferred as the material for the substrate 1, since it can be molded into various shapes and can be given gas barrier properties, which further broadens the range of uses.

[0086] Examples of plastics include, but are not limited to, polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, and copolymers thereof; polyamide resins such as nylon-6, nylon-66, nylon-12, metaxylylene adipamide, and copolymers thereof; styrene resins such as polystyrene, styrene-butadiene copolymer, and styrene-butadiene-acrylonitrile copolymer; poly(meth)acrylic acid ester; polyacrylonitrile; polyvinyl acetate; ethylene-vinyl acetate copolymer; ethylene-vinyl alcohol copolymer; polycarbonate; polyarylate; regenerated cellulose; polyimide; polyetherimide; polysulfone; polyethersulfone; polyetherketone; and ionomer resins.

[0087] When the gas barrier laminate is used as a food packaging material, the substrate 1 is preferably made of polyethylene, polypropylene, polyethylene terephthalate, nylon-6 or nylon-66.

[0088] As the plastic constituting the substrate 1, one type may be used alone, or two or more types may be blended and used.

[0089] The plastic may contain additives. The additives may be appropriately selected from known additives such as pigments, antioxidants, antistatic agents, ultraviolet absorbers, and lubricants depending on the intended use. One type of additive may be used alone, or two or more types may be used in combination.

[0090] The form of the substrate 1 is not particularly limited, and examples thereof include a film, a sheet, a cup, a tray, a tube, and a bottle. Among these, a film is preferred.

[0091] When the substrate 1 is a film, the film may be a stretched film or an unstretched film.

[0092] There are no particular restrictions on the thickness of the film, but from the viewpoint of the mechanical strength and processability of the resulting gas barrier laminate, it is preferably in the range of 1 to 200 μm, more preferably in the range of 5 to 100 μm.

[0093] The surface of the substrate 1 may be subjected to plasma treatment, corona treatment, ozone treatment, flame treatment, or radical activation treatment using ultraviolet (UV) or electron beams, etc., so that the coating liquid can be applied without being repelled by the substrate. The treatment method is appropriately selected depending on the type of substrate.

[0094] [Other layers] The gas barrier laminate according to this embodiment may further include one or more layers other than the substrate 1, the inorganic vapor deposition layer 2, and the coating layer 3, as necessary.

[0095] For example, the gas barrier laminate according to this embodiment may have only the coating layer 3 described above as the gas barrier coating layer, or may further include one or more other layers in addition to the coating layer 3. For example, a layer made of an inorganic compound such as aluminum oxide, silicon oxide, or aluminum may be formed on the surface of the substrate by sputtering, ion plating, or the like.

[0096] The gas barrier laminate according to this embodiment may further include an anchor coat layer between the substrate 1 and the inorganic vapor deposition layer 2, or between the inorganic vapor deposition layer 2 and the coating layer 3, for the purposes of increasing adhesion between layers or enabling the coating liquid for forming the coating layer to be applied without being repelled by the inorganic vapor deposition layer.

[0097] Fig. 2 is a cross-sectional view schematically showing a gas barrier laminate according to a second embodiment of the present invention. The gas barrier laminate 20 shown in Fig. 2 further comprises an anchor coat layer 4 between the substrate 1 and the inorganic vapor deposition layer 2, in addition to the gas barrier laminate 10 according to the first embodiment.

[0098] The anchor coat layer 4 can be formed by a conventional method using a known anchor coat liquid, such as a polyurethane resin, an acrylic resin, a melamine resin, a polyester resin, a phenol resin, an amino resin, or a fluororesin.

[0099] In addition to the resin, the anchor coating liquid may further contain an isocyanate compound for the purpose of improving adhesion and hot water resistance. The isocyanate compound may be any compound having one or more isocyanate groups in the molecule, and examples thereof include hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and tolylene diisocyanate. The anchor coating liquid may further contain a liquid medium for dissolving or dispersing the resin and the isocyanate compound.

[0100] The thickness of the anchor coat layer 4 is not particularly limited. The thickness of the anchor coat layer 4 may be, for example, in the range of 0.01 to 2 μm, or may be in the range of 0.05 to 1 μm. If the thickness is less than 0.01 μm, the layer is so thin that it may not fully exhibit its performance as an anchor coat layer. On the other hand, a thickness of 2 μm or less is preferable from the viewpoint of flexibility. If the flexibility is reduced, external factors may cause cracks to form in the anchor coat layer.

[0101] The gas barrier laminate according to this embodiment may further include another layer laminated onto the coating layer 3, or onto the surface of the substrate 1 or the inorganic vapor deposition layer 2, via an adhesive, as required, or may further include another layer formed by extrusion lamination of an adhesive resin.

[0102] The other laminated layers can be appropriately selected depending on the purpose, such as imparting strength, sealing properties, easy opening when sealed, design, light blocking properties, moisture resistance, etc., and are not particularly limited, and examples thereof include those made of the same material as the plastics described above for the substrate. In addition, paper, aluminum foil, etc. may also be used.

[0103] The thickness of the other layer to be laminated is preferably in the range of 1 to 1000 μm, more preferably in the range of 5 to 500 μm, even more preferably in the range of 5 to 200 μm, and particularly preferably in the range of 5 to 150 μm. The number of other layers to be laminated may be one or more.

[0104] The gas barrier laminate according to this embodiment may further include a printed layer, if necessary. The printed layer may be formed on a coating layer provided on the substrate, or may be formed on the surface of the substrate on which no coating layer is provided. Furthermore, when another layer is laminated, the printed layer may be formed on the other layer to be laminated.

[0105] [Method for producing gas barrier laminate] The gas barrier laminate according to this embodiment can be produced by a production method including the steps of forming an inorganic vapor deposition layer and forming a coating layer using the coating liquid for forming a coating layer described below. This production method may further include the steps of forming other layers such as an anchor coat layer and / or forming a printing layer, as necessary.

[0106] As an example of a method for producing the gas barrier laminate according to this embodiment, a method for producing the gas barrier laminate 20 shown in Fig. 2 will be described below. In the production method described here, the coating layer 3 consists of a single layer.

[0107] In the method for producing the gas barrier laminate 20, the anchor coat layer 4 is formed on the substrate 1. The anchor coat layer 4 can be formed by applying the anchor coat liquid described above to the substrate 1 and drying the formed coating film. There are no particular limitations on the method for applying the anchor coat liquid, and it can be carried out using well-known printing methods such as offset printing, gravure printing, and silk screen printing, or well-known coating methods such as roll coating, knife edge coating, and gravure coating. By drying the formed coating film, the solvent is removed and hardening proceeds, forming the anchor coat layer 4.

[0108] In the method for producing the gas barrier laminate 20, the inorganic vapor deposition layer 2 is formed on the anchor coat layer 4. Various methods are known for forming the inorganic vapor deposition layer 2, such as vacuum deposition, sputtering, ion plating, and chemical vapor deposition (CVD), and any of these methods may be used, but it is common to form the inorganic vapor deposition layer by vacuum deposition. The heating means of the vacuum deposition apparatus used in the vacuum deposition method may be an electron beam heating method, a resistance heating method, an induction heating method, or the like, and any of these may be used. Furthermore, in order to improve the adhesion of the inorganic vapor deposition layer 2 to the anchor coat layer 4 and the density of the inorganic vapor deposition layer 2, a plasma assist method or an ion beam assist method can also be used. In order to increase the transparency of the inorganic vapor deposition layer 2, reactive vapor deposition may be performed by blowing oxygen gas or the like during vapor deposition.

[0109] In the method for producing the gas barrier laminate 20, the coating layer 3 is formed on the inorganic vapor deposition layer 2. The coating layer 3 can be formed by applying a coating liquid for forming a coating layer, which is prepared by the method described below, onto the inorganic vapor deposition layer 2 and drying the resulting coating film.

[0110] -Method for preparing coating solution for forming coating layer The coating liquid for forming a coating layer uses an organic solvent (e) as a solvent or dispersion medium. That is, this coating liquid contains a carboxyl group-containing polymer (a), polyvalent metal-containing particles (b), a surfactant (c), and an organic solvent, and is a dispersion liquid in which the polyvalent metal-containing particles (b) are dispersed. In one embodiment, the coating liquid for forming a coating layer preferably further contains a silicon-containing compound (d). Below, a preparation method when the coating for forming a coating layer contains the optional silicon-containing compound (d) is described.

[0111] The organic solvent (e) is used in an amount sufficient to uniformly dissolve the carboxyl group-containing polymer (a) and uniformly disperse the polyvalent metal-containing particles. Therefore, the organic solvent used should be one that dissolves the carboxyl group-containing polymer but does not substantially dissolve the polyvalent metal compound, and can disperse it in the form of particles.

[0112] In addition, as the organic solvent (e), a polar organic solvent that dissolves the carboxy group-containing polymer (a) is generally used, but an organic solvent that does not have a polar group (heteroatom or atomic group having a heteroatom) may be used in combination with the polar organic solvent.

[0113] Examples of the organic solvent (e) that can be preferably used include alcohols such as methanol, ethanol, isopropanol, n-propanol, and n-butanol; and polar organic solvents such as dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, tetramethylurea, hexamethylphosphoric triamide, and γ-butyrolactone.

[0114] In addition to the polar organic solvents described above, the organic solvent (e) may suitably be hydrocarbons such as benzene, toluene, xylene, hexane, heptane, and octane; ketones such as acetone and methyl ethyl ketone; halogenated hydrocarbons such as dichloromethane; esters such as methyl acetate; and ethers such as diethyl ether. Hydrocarbons such as benzene that do not have a polar group are generally used in combination with a polar organic solvent.

[0115] The coating liquid may contain only the organic solvent (e) as a solvent or dispersion medium, or may further contain water. The inclusion of water improves the solubility of the carboxyl group-containing polymer (a) and improves the coatability and workability of the coating liquid. The water content of the coating liquid may be, in mass fraction, 100 ppm or more, 1,000 ppm or more, 1,500 ppm or more, or 2,000 ppm or more.

[0116] The water content of this coating liquid is preferably 50,000 ppm or less, more preferably 10,000 ppm or less, and even more preferably 5,000 ppm or less, in terms of mass fraction.

[0117] To prepare the coating liquid for forming the covering layer, first, the carboxyl group-containing polymer (a) is uniformly dissolved in the organic solvent (e), and then the silicon-containing compound (d) is added thereto to prepare a carboxyl group-containing polymer solution.

[0118] On the other hand, polyvalent metal-containing particles (b), surfactant (c), and organic solvent (e) are mixed and, if necessary, subjected to a dispersion treatment to prepare a dispersion liquid. The dispersion treatment is performed so that the average particle diameter of the polyvalent metal-containing particles (b) reaches a predetermined value. If the average particle diameter of the polyvalent metal-containing particles (b) in the mixed liquid before the dispersion treatment is 10 μm or less, the dispersion treatment is not necessary; however, even in this case, the dispersion treatment is preferably performed. The dispersion treatment disaggregates the polyvalent metal-containing particles (b), stabilizing the coating liquid and improving the transparency of the gas barrier laminate obtained by applying the coating liquid. Furthermore, when the coating liquid is applied and the coating is dried, crosslinking between the carboxyl group-containing polymer (a) and the polyvalent metal ions derived from the polyvalent metal-containing particles (b) is facilitated, making it easier to obtain a gas barrier laminate with good gas barrier properties.

[0119] Dispersion methods include those using a high-speed stirrer, homogenizer, ball mill, or bead mill. Dispersion using a ball mill or bead mill can achieve high dispersion efficiency, and therefore a coating liquid with a stable dispersion state can be obtained in a relatively short time. In this case, the diameter of the balls or beads should be small, preferably 0.1 to 1 mm.

[0120] The coating liquid can be prepared by mixing the carboxyl group-containing polymer solution prepared as above with the dispersion of polyvalent metal-containing particles (b).In the above-mentioned preparation method, the silicon-containing compound (d) is added to the carboxyl group-containing polymer solution in advance, but the silicon-containing compound (d) may not be added to the carboxyl group-containing polymer solution, and may be added, for example, when mixing the carboxyl group-containing polymer solution with the dispersion of polyvalent metal-containing particles (b).

[0121] In the above coating liquid, the total concentration of components other than the organic solvent (e) is preferably within the range of 0.1 to 60 mass %, more preferably 0.5 to 25 mass %, and particularly preferably 1 to 20 mass %, in order to obtain a coating film or covering layer of a desired thickness with high workability.

[0122] The coating liquid may contain various additives, such as other polymers, thickeners, stabilizers, ultraviolet absorbers, antiblocking agents, softeners, inorganic layered compounds (e.g., montmorillonite), and colorants (dyes, pigments), as needed.

[0123] The method for applying the coating liquid is not particularly limited, but examples include methods using an air knife coater, a direct gravure coater, a gravure offset coater, an arc gravure coater, a reverse roll coater such as a top feed reverse coater, a bottom feed reverse coater, or a nozzle feed reverse coater, a five-roll coater, a lip coater, a bar coater, a bar reverse coater, or a die coater.

[0124] The method for drying the coating film is not particularly limited, but examples thereof include natural drying, drying in an oven set at a predetermined temperature, and using a dryer attached to a coater, such as an arch dryer, floating dryer, drum dryer, or infrared dryer.

[0125] Drying conditions can be appropriately selected depending on the drying method, etc. For example, in a method of drying in an oven, the drying temperature is preferably in the range of 40 to 150°C, more preferably in the range of 45 to 150°C, and particularly preferably in the range of 50 to 140°C. The drying time varies depending on the drying temperature, but is preferably in the range of 0.5 seconds to 10 minutes, more preferably in the range of 1 second to 5 minutes, and particularly preferably in the range of 1 second to 1 minute.

[0126] It is believed that during or after drying, the carboxyl group-containing polymer (a) and the polyvalent metal-containing particles (b) contained in the coating film react with each other to introduce an ionic crosslinking structure. To allow the ionic crosslinking reaction to proceed sufficiently, the dried film is preferably aged in an atmosphere with a relative humidity of preferably 20% or more, more preferably 40 to 100%, at a temperature of preferably 5 to 200°C, more preferably 20 to 150°C, for about 1 second to 10 days.

[0127] The gas barrier laminate obtained in this manner is ionically crosslinked, and therefore has excellent moisture resistance, water resistance, hot water resistance, and water vapor resistance. This gas barrier laminate also has excellent gas barrier properties under high humidity conditions, as well as low humidity conditions. The gas barrier laminate preferably has an oxygen permeability of 10 cm3 / (m2·day·MPa) or less, measured at a temperature of 30°C and a relative humidity of 70% according to JIS K-7126 Method B (constant pressure method) and ASTM D3985.

[0128] <Packaging and packaging items> The packaging material according to this embodiment includes the gas barrier laminate described above. This packaging material is used, for example, to produce a package for packaging an article.

[0129] The packaging body according to this embodiment includes the packaging material described above. This package may be made of the above-mentioned packaging material, or may include the above-mentioned packaging material and other components. In the former case, the package is, for example, the above-mentioned packaging material formed into a bag. In the latter case, the package is, for example, a container including the above-mentioned packaging material as a lid and a cylindrical container body with a bottom.

[0130] In this package, the packaging material may be a molded article. As described above, this molded article may be a container such as a bag, or a part of a container such as a lid. Specific examples of the package or a part thereof include a bag, a pouch with a spout, a laminated tube, an infusion bag, a container lid, and a paper container.

[0131] There is no particular limitation on the application of this packaging material, and this packaging material can be used to package a variety of items. The packaged article according to this embodiment includes the above-described package and contents contained therein.

[0132] As described above, the gas barrier laminate has excellent gas barrier properties and transparency. Therefore, packaging materials and packages containing this gas barrier laminate are preferably used as packaging materials and packages for items that are susceptible to deterioration due to the influence of oxygen, water vapor, etc., particularly as packaging materials and packages for food containing sulfur. These packaging materials and packages are also preferably used as packaging materials and packages for packaging chemicals such as pesticides and medicines, medical devices, machine parts, and industrial materials such as precision materials.

[0133] The gas barrier laminate does not deteriorate in gas barrier properties or interlayer adhesion when subjected to heat sterilization treatment such as boiling or retort treatment, and in fact tends to improve the gas barrier properties and interlayer adhesion. Therefore, the packaging material and packaging body may be a packaging material for heat sterilization and a packaging body for heat sterilization, respectively.

[0134] The packaging material for heat sterilization and the package for heat sterilization are used to package articles that are to be subjected to heat sterilization treatment after packaging. Examples of products that are heat sterilized after packaging include foods such as curry, stew, soup, sauce, and processed meat products.

[0135] Examples of heat sterilization treatment include boiling treatment and retort treatment, which are as described above. [Example]

[0136] The following describes tests carried out in connection with the present invention. <Preparation of coating solution for forming coating layer> A coating solution for forming a covering layer was prepared in the following manner. (Coating liquid 1) Polyacrylic acid (PAA) (Jurymer (registered trademark) AC-10LP, number average molecular weight 50,000, manufactured by Toagosei Co., Ltd.) was dissolved in 2-propanol with heating to prepare a PAA solution 1 with a concentration of 10% by mass.

[0137] 1.8 g of polyether phosphate ester (Disparlon® DA-375, manufactured by Kusumoto Chemical Industries, Ltd., solid content 100% by mass) was dissolved in 26.2 g of 2-propanol. Next, 12 g of zinc oxide (FINEX®-30, manufactured by Sakai Chemical Industry Co., Ltd.) with an average primary particle diameter of 35 nm was added to the solution and stirred. The resulting solution was dispersed for 1 hour using a planetary ball mill (P-7, manufactured by Fritsch). Zirconia beads with a diameter of 0.2 mm were used for this dispersion treatment. The beads were then sieved out of the solution to obtain ZnO dispersion 1 containing zinc oxide at a concentration of 30% by mass.

[0138] Next, 56 g of PAA solution 1, 15 g of ZnO dispersion 1, 0.1 g of 3-glycidoxypropyltrimethoxysilane (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent (SC agent), and 57.9 g of 2-propanol were mixed to prepare coating solution 1.

[0139] (Coating liquid 2) Coating liquid 2 was prepared in the same manner as in the preparation of coating liquid 1 above, except that the amount of PAA solution 1 was changed to 38 g and the amount of ZnO dispersion liquid 1 was changed to 20 g.

[0140] (Coating liquid 3-1) A PAA solution 2 was prepared by dissolving 20 g of a polyacrylic acid (PAA) aqueous solution (Aron (registered trademark) A-10H, manufactured by Toagosei Co., Ltd., number average molecular weight 200,000, solid content 25% by mass) in 58.9 g of distilled water. To this was added 0.44 g of aminopropyltrimethoxysilane (manufactured by Sigma-Aldrich Japan LLC), and the mixture was stirred uniformly to prepare coating solution 3-1.

[0141] (Coating liquid 3-2) Coating solution 3-2 was prepared by mixing 100 g of an aqueous dispersion of zinc oxide particles ("Z-143" manufactured by Sumitomo Osaka Cement Co., Ltd., solid content 30% by mass) and 1 g of a curing agent ("Liofol HAERTER UR 5889-21" manufactured by Henkel).

[0142] (Coating liquid 4-1) A PAA solution 2 was prepared by dissolving 20 g of a polyacrylic acid (PAA) aqueous solution (Aron (registered trademark) A-10H, manufactured by Toagosei Co., Ltd., number average molecular weight 200,000, solid content 25% by mass) in 20 g of distilled water.

[0143] ZnO dispersion liquid 2 was prepared by adding 0.6 g of zinc oxide (FINEX (registered trademark)-30 manufactured by Sakai Chemical Industry Co., Ltd.) to 7 g of distilled water. The entire amount of ZnO dispersion 2 prepared above was added to the entire amount of PAA solution 2 prepared above and dissolved, and then 57.12 g of distilled water and 38.1 g of 2-propanol were added to dilute the mixture. Next, 0.44 g of aminopropyltrimethoxysilane (Sigma-Aldrich Japan LLC) was added and stirred uniformly to obtain coating solution 4-1.

[0144] (Coating liquid 4-2) 1 g of sodium polyacrylate (Aqualic YS-100, manufactured by Nippon Shokubai) and 15 g of calcium carbonate (Hakuenka PZ, manufactured by Shiraishi Calcium) were added to 35 g of distilled water and dispersed for 1 hour in a planetary ball mill (P-7, manufactured by Fritsch). Zirconia beads with a diameter of 0.2 mm were used for this dispersion process. The beads were then sieved from the solution and diluted with distilled water to obtain a dispersion containing 1% by mass of sodium polyacrylate and 15% by mass of calcium carbonate. 1.65 g of a curing agent (BASF's "Basonat HW1000") was mixed with the total amount (100 g) of the obtained dispersion to obtain coating liquid 4-2.

[0145] (Coating liquid C1) Coating liquid C2 was prepared in the same manner as in the preparation of coating liquid 1 above, except that the amount of PAA solution 1 was changed to 36 g and the amount of ZnO dispersion liquid 1 was changed to 24 g.

[0146] (Coating liquid C2) Coating liquid C1 was prepared in the same manner as in the preparation of coating liquid 1 above, except that the amount of PAA solution 1 was changed to 50 g and the amount of ZnO dispersion liquid 1 was changed to 12 g.

[0147] <Preparation of anchor coat layer> In a dilution solvent (ethyl acetate), 1 part by mass of γ-isocyanatopropyltrimethoxysilane and 5 parts by mass of acrylic polyol were mixed and stirred. Next, tolylene diisocyanate (TDI) was added as an isocyanate compound so that the number of NCO groups was equal to the number of OH groups in the acrylic polyol. The resulting mixed solution was diluted with the dilution solvent to a concentration of 2% by mass to obtain anchor coating solution 1. GS-5756 manufactured by Mitsubishi Rayon Co., Ltd. was used as the acrylic polyol.

[0148] <Production of Gas Barrier Laminate> [Example 1] Anchor coating solution 1 was applied to one side of a biaxially stretched polypropylene film (manufactured by Mitsui Chemicals Tohcello Inc., product name: ME-1, thickness 20 μm) using a bar coater so that the thickness after drying would be 0.2 μm, and an anchor coating layer was formed by drying at 150° C. for 1 minute. An alumina vapor deposition layer 20 nm thick was formed on this anchor coating layer using a vacuum deposition device. Coating liquid 1 was applied onto this alumina vapor deposition layer using a bar coater. The coating film was dried in an oven at 50°C for 1 minute to form a coating layer with a thickness of 400 nm. In this way, laminate 1 was obtained.

[0149] [Example 2] Laminate 2 was produced in the same manner as in Example 1, except that coating liquid 2 was used instead of coating liquid 1 to form the coating layer.

[0150] [Example 3] Laminate 3 was produced in the same manner as in Example 2, except that Coating Liquid 2 was applied so that the coating layer had a thickness of 250 nm after drying.

[0151] [Example 4] Laminate 4 was produced in the same manner as in Example 1, except that Coating Liquid 1 was applied so that the coating layer had a thickness of 550 nm after drying.

[0152] [Example 5] The same method as in Example 1 was used up to the formation of the alumina vapor deposition layer, and a laminate consisting of a substrate layer / anchor coat layer / alumina vapor deposition layer was obtained. Next, Coating Liquid 3-1 was applied to the alumina vapor deposition layer using a bar coater so that the film thickness after drying would be 200 nm, forming a first coating layer. Next, after aging at 50°C for 48 hours, Coating Liquid 3-2 was applied to the first coating layer using a bar coater and dried in an oven at 50°C for 1 minute, forming a second coating layer with a film thickness of 200 nm. In this way, Laminate 5 was obtained.

[0153] [Example 6] Laminate 6 was produced in the same manner as in Example 5, except that Coating Liquid 3-1 was changed to Coating Liquid 4-1 and Coating Liquid 3-2 was changed to Coating Liquid 4-2.

[0154] [Comparative Example 1] For Example 1, a laminate 1C was produced in the same manner as in Example 1, except that the coating liquid 1 used for forming the coating layer was changed to coating liquid C1.

[0155] [Comparative Example 2] For Example 1, a laminate 2C was produced in the same manner as in Example 1, except that the coating liquid 1 used for forming the coating layer was changed to coating liquid C2.

[0156] [Measurement of film thickness] The cross-section of each laminate was observed with a transmission electron microscope, and the film thickness of the coating layer was measured.

[0157] [Measurement of fluorescence X-ray intensity] Using a fluorescence X-ray analyzer (manufactured by Rigaku Corporation, wavelength-dispersive small fluorescence X-ray analyzer "Supermini"), the fluorescence X-ray intensity (kcps) of polyvalent metal-containing particles (ZnO or CaCO3) in the coating layer, which is the surface layer of each laminate, was measured. Regarding zinc oxide (ZnO), as standard samples (PET with ZnO vapor-deposited), ZnO vapor-deposited films with film thicknesses of 0.25 nm, 0.18 nm, and 0.15 nm were prepared. The fluorescence X-ray (Kα line) intensity of Zn was measured for these standard samples, and a calibration curve was drawn as 4.8 kcps, 2.1 kcps, and 1.2 kcps in order. Based on the obtained calibration curve, the fluorescence X-ray (Kα line) intensity per unit area of the coating layer was determined.

[0158] Detection spectrum: Zn-Kα X-ray inter-excitation conditions: target Pb, tube voltage 50 kV, tube current 4.00 mA Spectrometer crystal: LiF Detector: SC (scintillation counter)

[0159] Similarly, a calibration curve was created for calcium carbonate (CaCO3), and the fluorescence X-ray intensity per unit area of the coating layer was determined.

[0160] [Measurement of UV absorbance] A 60 μm thick, non-oriented polypropylene (CPP) film was laminated onto the coating layer of each laminate using a two-component urethane adhesive. This was then folded with the CPP film facing inward, and three sides were heat-sealed to create a bag. Each bag was filled with water or an L-cysteine ​​(L-cys) aqueous solution (0.3% by mass) as the content, and the remaining side was heat-sealed to create a four-sided sealed bag filled with the content. Samples filled with water were retorted at 130°C for 60 minutes. Samples filled with an L-cysteine ​​(L-cys) aqueous solution (0.3% by mass) were retorted at 130°C for 30 minutes. After retorting, the four-sided sealed bags were opened and used as samples for UV absorbance measurement.

[0161] For each sample, UV absorbance X (abs) was measured using a UV-visible spectrophotometer (Shimadzu Corporation, UV-2450 UV-visible spectrophotometer). The measurement range was set to a wavelength of 300 nm to 550 nm. The absorbance X was determined by subtracting the absorbance X2 of the measurement sample at a wavelength of 500 nm from the absorbance X1 of the measurement sample at a wavelength of 350 nm. The results are shown in Table 1.

[0162] <Oxygen Transmission Rate (OTR)> A non-oriented polypropylene (CPP) film (60 μm thick) was laminated onto the coating layer of each laminate using a two-component urethane adhesive. This was folded with the CPP film facing inward, and three sides were heat-sealed to form a bag. Each resulting bag was filled with water or an L-cys aqueous solution (0.3% by mass) as the contents, and the remaining side was sealed by heat sealing to form a four-sided sealed bag filled with the contents. Samples filled with water were retorted at 130°C for 60 minutes. Samples filled with an L-cys aqueous solution (0.3% by mass) were retorted at 130°C for 30 minutes.

[0163] The oxygen transmission rate (OTR) of each sample after this retort treatment was measured at a temperature of 30°C and a relative humidity of 70% using an oxygen transmission rate measuring device, OX-TRAN (registered trademark), manufactured by MOCON Corp. The measurement method was in accordance with JIS K-7126 Method B (constant pressure method) and ASTM D3985, and the measurement value is expressed in units of cc / m. 2 The results are shown in Table 1.

[0164] [Table 1]

[0165] From Table 1, it can be seen that the gas barrier laminates of Examples 1 to 6 can maintain high oxygen barrier properties after moist heat treatment, and furthermore, even when the contents contain sulfur, the decrease in oxygen barrier properties due to the penetration of sulfur by moist heat treatment is suppressed, and the gas barrier laminates of Examples 1 to 6 have excellent oxygen barrier properties.

[0166] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention. [Explanation of symbols]

[0167] 1... substrate, 2... inorganic vapor deposition layer, 3... coating layer, 4... anchor coat layer, 10, 20... gas barrier laminate The inventions described in the original claims of this application are set forth below. [1] A gas barrier laminate comprising a substrate, an inorganic vapor deposition layer containing an inorganic oxide, and a coating layer in this order, the coating layer being composed of a single layer or multiple layers, the coating layer contains a carboxyl group-containing polymer and at least one type of polyvalent metal-containing particle, The total fluorescent X-ray intensity of the metal elements contained in the polyvalent metal-containing particles is 3.0 kcps or more and 8.0 kcps or less, and The absorbance X at a wavelength of 350 nm of the gas barrier laminate measured using an ultraviolet-visible spectrophotometer after hot water treatment at 130°C for 30 minutes using a 0.3 mass% aqueous solution of L-cysteine 1 absorbance at wavelength 500 nm X 2 The absorbance X obtained by subtracting the above satisfies the following formula (1): A gas barrier laminate. X=X 1 -X 2 ≧0.02(abs) (1) [2] The gas barrier laminate according to appendix [1], wherein the coating layer is a single layer. [3] The gas barrier laminate according to appendix [1], wherein the coating layer comprises a laminate unit in which a first coating layer containing the carboxyl group-containing polymer and a second coating layer containing the polyvalent metal-containing particles are adjacent to each other. [4] The gas barrier laminate according to appendix [3], wherein the first coating layer further contains polyvalent metal-containing particles different from the polyvalent metal-containing particles contained in the second coating layer. [5] The gas barrier laminate according to any one of appendices [1] to [4], wherein the polyvalent metal contained in the polyvalent metal-containing particles is a divalent metal. [6] The gas barrier laminate according to any one of appendices [1] to [5], wherein the coating layer contains at least one of a zinc compound and a calcium compound as the polyvalent metal-containing particles. [7] The gas barrier laminate according to any one of appendices [1] to [6], wherein the carboxyl group-containing polymer contains a structural unit derived from at least one α,β-monoethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. [8] The gas barrier laminate according to any one of appendices [1] to [7], wherein the coating layer has a thickness of 230 nm or more and 600 nm or less. [9] A package containing the gas barrier laminate according to any one of appendices [1] to [8].

[10] A packaged article comprising the package described in Appendix [9] and the contents contained therein.

Claims

1. A gas barrier laminate comprising a substrate, an inorganic vapor deposition layer containing an inorganic oxide, and a coating layer in this order, wherein the coating layer is a single layer, the coating layer contains a carboxyl group-containing polymer and at least one type of polyvalent metal-containing particle, the total fluorescent X-ray intensity of the metal elements contained in the polyvalent metal-containing particles is 3.0 kcps or more and 8.0 kcps or less, and The absorbance X of the gas barrier laminate at a wavelength of 350 nm measured using an ultraviolet-visible spectrophotometer after hot water treatment at 130° C. for 30 minutes using a 0.3% by mass aqueous solution of L-cysteine １ absorbance X at a wavelength of 500 nm ２ The absorbance X obtained by subtracting the above satisfies the following formula (1): A gas barrier laminate. X=X １ -X ２ ≧0.02(abs) (1)

2. 2. The gas barrier laminate according to claim 1, wherein the coating layer comprises a laminate unit in which a first coating layer containing the carboxyl group-containing polymer and a second coating layer containing the polyvalent metal-containing particles are adjacent to each other.

3. 3. The gas barrier laminate according to claim 2, wherein the first coating layer further contains polyvalent metal-containing particles that are different from the polyvalent metal-containing particles contained in the second coating layer.

4. 4. The gas barrier laminate according to claim 1, wherein the polyvalent metal contained in the polyvalent metal-containing particles is a divalent metal.

5. 5. The gas barrier laminate according to claim 1, wherein the coating layer contains at least one of a zinc compound and a calcium compound as the polyvalent metal-containing particles.

6. 6. The gas barrier laminate according to claim 1, wherein the carboxy group-containing polymer contains a structural unit derived from at least one α,β-monoethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid.

7. 7. The gas barrier laminate according to claim 1, wherein the coating layer has a thickness of 230 nm or more and 600 nm or less.

8. A package comprising the gas barrier laminate according to any one of claims 1 to 7.

9. A packaged article comprising the package of claim 8 and contents contained therein.

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