JP2020163649A - Gas barrier film - Google Patents

Abstract

To provide a gas barrier film which can be used as a packaging material even in the form of a composite film constituted of a water-soluble polymer, an aqueous polyurethane resin, and an inorganic laminar mineral, in direct contact with a moisture-containing content.SOLUTION: A gas barrier film 1 includes a resin substrate 3 and a film 5 positioned so as to be in contact with at least one surface of the resin substrate 3. The film 5 is formed of a coating agent including a water-soluble polymer (A), an inorganic laminar mineral (B), an aqueous polyurethane resin (C), and a hardening agent (D). Potassium permanganate consumption of a test liquid which is obtained by bringing the film 5 into contact with distilled water of 2 mL per surface area of 1 cm2 of the film 5 and retaining it at 60°C for 30 minutes, is 10.0 μg/mL or less, and its degree of oxygen permeation at 30°C and with relative humidity of 60% is 2.0 cm3/(m2.day.atm) or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas barrier film.

Packaging materials used for packaging foods, pharmaceuticals, etc. contain gases (water vapor, oxygen, etc.) that alter the contents in order to suppress deterioration and putrefaction of the contents and maintain their functions and properties. The property of blocking entry (gas barrier property) is required. In addition, the packaging material is required to exhibit high gas barrier properties regardless of the storage environment.

As the packaging material having a gas barrier property, a material having a gas barrier layer is generally used. The gas barrier layer includes a metal foil made of a metal such as aluminum, a metal vapor deposition film, a water-soluble polymer such as polyvinyl alcohol or an ethylene-vinyl alcohol copolymer, a resin film made of a resin such as polyvinylidene chloride, and the above-mentioned highly water-soluble layer. A composite film of a molecule and an inorganic layered mineral or the like is used (Patent Documents 1 to 5).

The composite film of the water-soluble polymer and the inorganic layered mineral is superior in oxygen barrier property in a high humidity atmosphere as compared with the resin film made of the water-soluble polymer. However, a composite film of a water-soluble polymer and an inorganic layered mineral generally has a problem of low adhesion to a base material.

In Patent Document 6, as a gas barrier film having excellent adhesion to a base material while exhibiting good gas barrier properties, a water-soluble polymer and a water-soluble or water-dispersible film are formed on at least one surface of a thermoplastic resin base material. A gas barrier film has been proposed in which a film is formed mainly composed of a polyester-based urethane resin of the above and an inorganic layered mineral having an average particle size of 5 μm or less and a thickness of 500 nm or less. Further, Patent Document 6 proposes that the film contains 0.01 to 10% by mass of a cross-linking agent in order to maintain adhesion under high humidity.

Japanese Unexamined Patent Publication No. 2001-287294 JP-A-11-165369A JP-A-6-93133 JP-A-9-150484 Japanese Patent No. 3764109 Japanese Patent No. 3351208

However, according to the study by the present inventors, the composite film of the water-soluble polymer, the water-based polyurethane resin, and the inorganic layered mineral contains an organic substance that easily elutes with water. This organic substance elutes even when the composite membrane contains a cross-linking agent (curing agent). Therefore, the gas barrier film having this composite membrane cannot be used as a packaging material in a form in which the composite membrane comes into direct contact with a water-containing content such as food, and another layer is formed between the composite membrane and the content. It is necessary to take measures such as intervening.

An object of the present invention is to provide a gas barrier film that can be used as a packaging material even in a form in which a composite film of a water-soluble polymer, an aqueous polyurethane resin, and an inorganic layered mineral comes into direct contact with a content containing water. ..

The present invention has the following aspects.
[1] A resin base material and a film located in contact with at least one surface of the resin base material are provided.
The film is formed of a coating agent containing a water-soluble polymer (A), an inorganic layered mineral (B), an aqueous polyurethane resin (C), and a curing agent (D).
The potassium permanganate consumption of the test solution obtained by bringing 2 mL of distilled water per 1 cm ² of the surface area of the film into contact with the film and holding it at 60 ° C. for 30 minutes is 10.0 μg / mL or less.
Gas barrier film 30 ° C., the oxygen permeability under a relative humidity of ^60%, and wherein the at ^{2.0cm 3 / (m 2 · day} · atm) or less.
[2] The gas barrier film of the above [1], wherein the total mass of the water-soluble polymer (A) and the aqueous polyurethane resin (C) per unit area of the film is 0.47 g / m ² or less.
[3] The water-soluble polymer (A) is 25 to 80% by mass, the inorganic layered mineral (B) is 8 to 20% by mass, and the aqueous polyurethane resin (C) ratio is 5 with respect to the total mass of the film. The gas barrier film of the above [1] or [2], wherein the curing agent (D) is 5 to 20% by mass in an amount of about 60% by mass.
[4] The gas barrier film according to any one of [1] to [3], wherein the film has a thickness of 0.32 to 0.55 μm.
[5] Of the above [1] to [4], the mass ratio ((D) / (A) ratio) of the curing agent (D) to the water-soluble polymer (A) is 10/90 to 30/70. Either gas barrier film.
[6] The gas barrier film according to any one of [1] to [5] above, wherein the resin base material is a polyolefin-based resin film, a polyester-based resin film, or a polyamide-based resin film.

In the gas barrier film of the present invention, the elution of organic substances that easily elute into water in the composite film of the water-soluble polymer, the aqueous polyurethane resin, and the inorganic layered mineral is suppressed. In addition, the gas barrier property is sufficiently excellent. Therefore, it can be used as a packaging material even in a form in which the composite film comes into direct contact with the contents containing water.

It is a schematic cross-sectional view which shows an example of the gas barrier film which concerns on embodiment. It is a schematic cross-sectional view which shows the other example of the gas barrier film which concerns on embodiment.

An embodiment of the gas barrier film of the present invention will be described. It should be noted that the present embodiment is specifically described in order to better understand the gist of the invention, and is not limited to the present invention unless otherwise specified.
The dimensional ratios in FIGS. 1 and 2 are different from the actual ones for convenience of explanation.

The gas barrier film according to the embodiment of the present invention includes a resin base material and a film located in contact with at least one surface of the resin base material.

FIG. 1 is a schematic cross-sectional view showing an example of a gas barrier film according to the present embodiment.
The gas barrier film 1 of this example has a resin base material 3 and a film 5 located in contact with one surface of the resin base material 3.

FIG. 2 is a schematic cross-sectional view showing another example of the gas barrier film according to the present embodiment.
The gas barrier film 2 of this example has a resin base material 3 and a film 5 located in contact with one surface of the resin base material 3 and each of the other surfaces.

Oxygen permeability of the gas barrier film according to the present ^{embodiment, 2.0cm 3 / (m 2 ·} day · atm) or ^{less, 1.0cm 3 / (m 2 ·} day · atm) or less. When the oxygen permeability is not more than the above upper limit value, it is useful as a packaging material.
The oxygen permeability is a value measured under the conditions of 30 ° C. and 60% relative humidity.
The oxygen permeability of the gas barrier film can be adjusted by the composition of the coating agent forming the film and the thickness of the film.

(Resin base material)
The resin base material contains a resin. Examples of the resin constituting the resin base material include polyolefin-based resin, polyester-based resin, polyamide-based resin, vinyl-based resin, acrylic-based resin, cellophane, engineering plastic, and the like. Examples of the polyolefin resin include homopolymers and copolymers of olefins having 2 to 10 carbon atoms, and specific examples thereof include polyethylene, polypropylene, poly (1-butene), ethylene-propylene copolymer, and ethylene-. 1-butene copolymer, ethylene-propylene-1-butene copolymer, ethylene-acrylic acid copolymer, ionomer obtained by cross-linking ethylene-acrylic acid copolymer with metal ions, propylene-1-butene copolymer, Examples thereof include a propylene-pentene copolymer. Examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyamide resin include aliphatic polyamides such as nylon 6 and nylon 66, and aromatic polyamides such as polymethoxylylen adipamide. Examples of the vinyl resin include polystyrene, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, ethylene-vinyl alcohol copolymer and the like. Examples of the acrylic resin include homopolymers and copolymers of (meth) acrylic monomers such as (meth) acrylate and (meth) acrylonitrile, and specific examples thereof include polymethylmethacrylate and polyacrylonitrile. Can be mentioned. (Meta) acrylic is a general term for acrylic and methacrylic, and the same applies to (meth) acrylate and (meth) acrylonitrile. Examples of engineering plastics include polycarbonate and polyimide. One of these resins may be used alone, or two or more of these resins may be used in combination.

Resin substrates include fillers, anti-blocking agents (hereinafter, also referred to as "AB agents"), antistatic agents, plasticizers, lubricants, slip agents, heat-resistant stabilizers, weather-resistant stabilizers, antioxidants, antifogging agents, etc. It may contain additives such as an ultraviolet absorber, a nucleating agent, a pigment, and a dye. Any one of these additives may be used alone, or two or more thereof may be used in combination.

The AB agent causes irregularities on the surface of the resin base material and the surface of the gas barrier layer formed on the surface to enhance the blocking resistance of the gas barrier film, facilitate the winding of the gas barrier film, and process the gas barrier film. Improve the characteristics. Therefore, the resin base material preferably contains an AB agent.
When the resin base material contains the AB agent, the AB agent is dispersed in the resin base material, and a plurality of protrusions derived from the AB agent are locally present on one surface or the other surface of the resin base material. .. On one surface and the other surface, the AB agent may be exposed or may be covered with a resin.

The AB agent is solid particles, and examples thereof include organic particles and inorganic particles. Examples of the organic particles include acrylic resin particles such as polymethylmethacrylate particles, polystyrene particles, and polyamide particles. These organic particles can be obtained by, for example, emulsion polymerization or suspension polymerization. Examples of the inorganic particles include silica particles, zeolite, talc, kaolinite, and feldspar. Any one of these AB agents may be used alone, or two or more thereof may be used in combination.

The average particle size of the AB agent is preferably 0.1 to 4 μm in consideration of, for example, the appearance and transparency of the gas barrier film, the possibility of the AB agent falling off, and the anti-blocking performance.
The average particle size of the AB agent is the weight average diameter measured by the Coulter method.
If the average particle size of the AB agent is too large, large protrusions are formed on the surface of the resin base material, and when the film is formed, defects that serve as gas permeation paths are likely to occur in the film, and the oxygen barrier property is lowered. There is a risk of

When the resin base material contains an AB agent, the content of the AB agent is preferably 0.1 to 0.5 parts by mass with respect to 100 parts by mass of the resin constituting the resin base material, for example. When the content of the AB agent is at least the above lower limit value, it is easy to improve the processing characteristics of the resin base material and the film used as the raw material thereof. When the content of the AB agent is not more than the above upper limit value, it is easy to suppress the deterioration of the oxygen barrier property of the gas barrier film.

The resin base material may be a single layer or two or more layers. The resin base material includes a single-layer film composed of a single resin, a single-layer or laminated film composed of a plurality of resins, a resin layer and another base material (metal, wood, paper, ceramics, etc.). Examples thereof include laminated laminated films.
As an example of a laminated film composed of a plurality of resins, from one surface side, a first surface layer containing a resin and an AB agent, a base layer containing a resin and not containing an AB agent, and a second surface layer containing a resin and an AB agent. However, a film laminated in this order can be mentioned.

As the resin base material, a polyolefin-based resin film (particularly, polypropylene film, etc.), a polyester-based resin film (particularly, a polyethylene terephthalate-based resin film), or a polyamide-based resin film (particularly, a polypropylene-based resin film) or a polyamide-based resin film (particularly, a polypropylene film) or a polyamide-based resin film (particularly, a polyethylene terephthalate-based resin film), or a polyamide-based resin film (particularly, a polypropylene film, etc.) In particular, a nylon film) is preferable, and a polyolefin resin film is particularly preferable.

The resin base material may be an unstretched film or a uniaxial or biaxially stretched oriented film.
As the resin base material, a biaxially stretched polypropylene film (OPP) is particularly preferable from the viewpoint of excellent water vapor barrier property. The OPP may be a film of at least one polymer selected from homopolymers, random copolymers and block copolymers. Homopolymers are polypropylenes consisting of elemental propylene alone. The random copolymer is polypropylene in which propylene, which is the main monomer, and a small amount of comonomer different from propylene are randomly copolymerized to form a homogeneous phase. The block copolymer is polypropylene in which propylene, which is the main monomer, and the above-mentioned comonomer are copolymerized in a block-like manner or polymerized in a rubber-like manner to form a heterogeneous phase. When the resin base material is OPP, the OPP may be one layer or two or more layers.

In the resin base material, chemical treatment, solvent treatment, corona treatment, and low temperature plasma are used to improve the wettability to the coating agent and the adhesive strength to the film on the surface on which the film is laminated, that is, the surface to which the coating agent is applied. Surface treatment such as treatment and ozone treatment may be applied.
In the resin base material, the surface on which the film is laminated may be subjected to an anchor coating or an undercoat treatment.

The thickness of the resin base material is not particularly limited, and is appropriately selected according to the price and application while considering the suitability as a packaging material and the suitability for laminating other films, but practically 3 It is ~ 200 μm, preferably 5 to 120 μm, and more preferably 10 to 100 μm.
The thickness of the resin base material is measured by observing a cross section of the resin base material or the gas barrier film cut in the thickness direction with a scanning electron microscope (SEM). When the resin base material contains the AB agent, the thickness of the resin base material is the thickness in the flat portion where the protrusions derived from the AB agent do not exist.

(Film)
The film is formed of a coating agent containing a water-soluble polymer (A), an inorganic layered mineral (B), an aqueous polyurethane resin (C), and a curing agent (D), that is, a water-soluble polymer and an aqueous film. It is a composite film of polyurethane resin and inorganic layered mineral. The gas barrier film provided with such a film exhibits excellent oxygen barrier properties even in a high humidity atmosphere, has sufficient adhesion strength to other materials as a packaging material and film aggregation strength, and is transparent not found in metal foils and metal vapor deposition films. It has advantages such as having a stretch resistance and no risk of generating harmful substances such as dioxin.
The film is obtained by forming a coating film made of a coating agent on at least one surface of the resin base material by a wet coating method and drying the coating film. The coating film is a wet film, and the film is a dry film. The coating agent will be described in detail later.

The film has a potassium permanganate consumption of 10.0 μg / mL or less, which is obtained by bringing 2 mL of distilled water per 1 cm ² of the surface area of the film into contact with the film and holding it at 60 ° C. for 30 minutes. Potassium permanganate consumption is an index of the amount of organic matter that easily elutes into water in the film. When the consumption of potassium permanganate is 10.0 μg / mL or less, the gas barrier film can be used as a packaging material even in a form in which the film comes into direct contact with the content containing water.
The smaller the consumption of potassium permanganate, the more preferable, and the lower limit is not particularly limited.

The potassium permanganate consumption in the present specification is calculated by the following measuring method. This measuring method is based on the potassium permanganate consumption test method described in Notification No. 370 of the Ministry of Health and Welfare, "Standards for Foods, Additives, etc."
"Measurement method of potassium permanganate consumption"
(1) Heat ² mL of distilled water per 1 cm ² of the surface area of the sample (gas barrier film) film to 60 ° C., bring the sample film into contact with this water, leave it at 60 ° C for 30 minutes, and then water. To collect. 400 mL of this water is prepared for each sample and used as a test solution.
(2) Put 100 mL of distilled water, 5 mL of 30 mass% sulfuric acid and 5 mL of 0.002 mol / L potassium permanganate solution in an Erlenmeyer flask, boil for 5 minutes, then discard the solution and wash with distilled water. Take 100 mL of the test solution into the washed Erlenmeyer flask, add 5 mL of diluted sulfuric acid (three-fold diluted sulfuric acid (JIS special grade)), add 10 mL of 0.002 mol / L potassium permanganate solution, and heat for 5 minutes. Boil. Then, the heating was stopped, and immediately 10 mL of 0.005 mol / L sodium oxalate solution was added to decolorize the mixture, and then titrated with a 0.002 mol / L potassium permanganate solution until the slight red color remained, and the titration amount a. (ML) is used as the titration amount of 0.002 mol / L potassium permanganate solution in this test.
(3) Perform the same operation as in (2) above except that 100 mL of distilled water is taken in place of the test solution in the washed Erlenmeyer flask, and the titration amount b (mL) is 0.002 mol / L in the blank test. Titrate the potassium permanganate solution.
(4) The amount of potassium permanganate consumed is calculated by the following formula.
Potassium permanganate consumption (μg / mL) = ((ab) x 0.316 x f x 1000) / 100
Here, f indicates the concentration factor of the potassium permanganate solution.

The consumption of potassium permanganate is the total mass (g / m ² ) of the water-soluble polymer (A) and the aqueous polyurethane resin (C) per unit area of the film, and the curing agent for the water-soluble polymer (A) ( It can be adjusted by the mass ratio of D) and the thickness of the film.
The mass of each component in the film is the mass in terms of solid content.

The content of the water-soluble polymer (A) in the film is preferably 25 to 80% by mass, more preferably 35 to 70% by mass, based on the total mass of the film. When the content of the water-soluble polymer (A) is at least the above lower limit value, the inorganic layered mineral (B) is likely to be dispersed. When the content of the water-soluble polymer (A) is not more than the above upper limit value, a large amount of the water-based polyurethane resin (C) can be easily blended.

The content of the inorganic layered mineral (B) in the film is preferably 8 to 20% by mass, more preferably 8 to 15% by mass, based on the total mass of the film. When the content of the inorganic layered mineral (B) is at least the above lower limit value, the oxygen barrier property in a high humidity environment is likely to be effectively exhibited. When the content of the inorganic layered mineral (B) is not more than the above upper limit value, it is easy to maintain the cohesive strength of the film.

The content of the aqueous polyurethane resin (C) in the film is preferably 5 to 60% by mass, more preferably 10 to 40% by mass, based on the total mass of the film. When the content of the aqueous polyurethane resin (C) is at least the above lower limit value, the adhesion strength of the film to the resin base material is more excellent. When the content of the aqueous polyurethane resin (C) is not more than the above upper limit value, the water dispersion stability of the coating agent tends to be improved.

The mass ratio ((C) / (A) ratio) of the aqueous polyurethane resin (C) to the water-soluble polymer (A) is preferably 85/15 to 5/95, more preferably 75/25 to 10/90. 70/30 to 15/85 is more preferable. When the content of the aqueous polyurethane resin (C) is smaller than the ratio of (C) / (A) to 85/15, it is easy to suppress the occurrence of unevenness during coating. When the content of the aqueous polyurethane resin (C) is higher than the ratio of (C) / (A) to 5/95, the wettability to the resin base material is good, and unevenness due to repelling during coating occurs. Easy to suppress. Since unevenness during coating leads to deterioration of appearance and deterioration of oxygen barrier property, it is easy to suppress deterioration of appearance and deterioration of oxygen barrier property by suppressing the occurrence of unevenness during coating. Therefore, when the (C) / (A) ratio is within the above range, the coating agent can be applied evenly, and it is easy to form a film having a good appearance and oxygen barrier property.

The content of the curing agent (D) in the film is preferably 5 to 20% by mass, more preferably 5 to 15% by mass, based on the total mass of the film. When the content of the curing agent (D) is at least the above lower limit value, the consumption of potassium permanganate is likely to be 10.0 μg / mL or less. Further, when the content of the curing agent (D) is within the above range, the cohesive force of the film and the adhesion strength to the resin base material can be sufficiently enhanced while maintaining good wettability to the resin base material. ..

The mass ratio ((D) / (A) ratio) of the curing agent (D) to the water-soluble polymer (A) is preferably 10/90 to 30/70, more preferably 15/85 to 25/75. When the content of the curing agent (D) is larger than the ratio of (D) / (A) to 10/90, the consumption of potassium permanganate is likely to be 10.0 μg / mL or less. When the content of the curing agent (D) is smaller than the ratio of (D) / (A) to 30/70, the cohesive strength of the film and the resin base material are maintained while maintaining good wettability to the resin base material. The adhesion strength of the plastic can be sufficiently increased.

The total content of the water-soluble polymer (A), the inorganic layered mineral (B), the aqueous polyurethane resin (C), and the curing agent (D) is preferably 85% by mass or more with respect to the total mass of the film. 90% by mass or more is more preferable, and 95% by mass or more is further preferable. The upper limit of the total content is not particularly limited and may be 100% by mass.

The thickness of the film, that is, the thickness of the coating film made of the coating agent after drying may be, for example, 0.1 μm to 3 μm.
The thickness of the film is preferably 0.32 to 0.55 μm, more preferably 0.35 to 0.55 μm. When the thickness of the film is at least the above lower limit value, it is easy to form a uniform coating film surface, and it is easy to obtain a sufficient oxygen barrier property. When the thickness of the film is not more than the above upper limit value, the consumption of potassium permanganate is likely to be 10.0 μg / mL or less.

The total mass of the water-soluble polymer (A) and the water-based polyurethane resin (C) per unit area of the film is preferably 0.47 g / m ² or less. When the total mass of the water-soluble polymer (A) and the aqueous polyurethane resin (C) is 0.47 g / m ² or less, the consumption of potassium permanganate is likely to be 10.0 μg / mL or less.

(Coating agent)
The coating agent according to the present embodiment contains a water-soluble polymer (A), an inorganic layered mineral (B), an aqueous polyurethane resin (C), and a curing agent (D) as main constituents.
The coating agent contains components (other components) other than the water-soluble polymer (A), inorganic layered mineral (B), aqueous polyurethane resin (C), and curing agent (D) as long as the effects of the present invention are not impaired. It may be contained.

The coating agent typically comprises an aqueous medium in which each of the above components is dissolved or dispersed.
Examples of the aqueous medium include water, a water-soluble or hydrophilic organic solvent, or a mixed solvent thereof. As the aqueous medium, water or a mixed solvent containing water as a main component is preferable.
The content of water in the aqueous medium is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.
Examples of the water-soluble or hydrophilic organic solvent include alcohols such as ethanol and isopropanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; cellosolves; carbitols; nitriles such as acetonitrile. Be done.

<Water-soluble polymer (A)>
"Water-soluble polymer" refers to a polymer that is soluble in water. The term "dissolution" as used herein refers to a state in which a polymer as a solute is dispersed in water as a solvent at the molecular chain level to form a uniform system. More specifically, it refers to a state in which the intermolecular force with water molecules is stronger than the intermolecular force between molecular chains of a polymer chain, the entanglement of the polymer chains is disentangled, and the polymer chains are uniformly dispersed in water.
In the present specification, the polymer means a compound having a mass average molecular weight of 10,000 or more. The mass average molecular weight can be measured by gel permeation chromatography (GPC) and determined using polystyrene as a standard substance.

Specific examples of the water-soluble polymer (A) include polyvinyl alcohol resins (polyvinyl alcohol-based polymers and derivatives thereof, etc.), other vinyl-based polymers (polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, and esters thereof, etc.). Salts thereof and their copolymers, polyhydroxyethyl methacrylate and its copolymers, etc.), cellulose derivatives (carboxymethyl cellulose, hydroxyethyl cellulose, etc.), starches (oxidized starch, etherified starch, dextrin, etc.), polar groups Copolymerized polyester (polypoly containing a sulfoisophthalic acid structure, etc.), urethane-based polymer (excluding aqueous polyurethane resin described later), or functional group-modified weight in which the carboxyl group of these various polymers is modified. Coalescence and the like can be mentioned. The water-soluble polymer (A) preferably has a degree of polymerization of 300 or more in consideration of the film cohesive strength.
The water-soluble polymer (A) contained in the coating agent may be one kind or two or more kinds.

The water-soluble polymer (A) preferably contains at least a polyvinyl alcohol resin, and more preferably contains a polyvinyl alcohol resin having a saponification degree of 95% or more and a degree of polymerization of 300 or more. The degree of polymerization of the polyvinyl alcohol resin is preferably 300 to 2400, more preferably 450 to 2000. The higher the degree of saponification and the degree of polymerization of the polyvinyl alcohol resin, the lower the hygroscopic swelling property. When the saponification degree of the polyvinyl alcohol resin is 95% or more, sufficient gas barrier properties can be easily obtained. When the degree of polymerization is 2400 or less, the viscosity of the coating agent is sufficiently low, it is easy to mix it uniformly with other components, and problems such as deterioration of gas barrier property and adhesion strength are unlikely to occur.
The degree of saponification and the degree of polymerization of the polyvinyl alcohol resin can be measured by the method described in JIS K 6726.

<Inorganic layered mineral (B)>
The "inorganic layered mineral" refers to an inorganic compound in which ultrathin (for example, 10 to 500 nm thick) unit crystal layers are overlapped to form one layered particle. Since the film contains the inorganic layered mineral (B), it exerts a maze effect of lengthening the path through which the gas permeates, and it is easy to obtain a good oxygen barrier property even in a high humidity atmosphere.
As the inorganic layered mineral (B), a compound having both or one of the properties of swelling and cleavage in water is preferable, and a clay compound having swelling property in water is particularly preferable. More specifically, the inorganic layered mineral (B) is preferably a clay compound in which water is coordinated between ultrathin unit crystal layers and has both absorption and swelling properties. In general, such clay compounds include a layer in which Si ⁴⁺ coordinates with respect to O ^2- to form a tetrahedral structure, and Al ³⁺ , Mg ²⁺ , Fe ²⁺ , Fe ^{3+ and the} like are O ^2- and OH ^−. It is a compound in which layers that are coordinated with each other to form an octahedral structure are bonded one-to-one or 2: 1 and are stacked to form a layered structure. This clay compound may be a natural compound or a synthesized compound.

Typical examples of the inorganic layered mineral (B) include hydrous silicates such as phyllosilicate minerals, and for example, kaolinite clay minerals such as halloysite, kaolinite, enderite, dikite, and nacrite; anti Anti-Golite clay minerals such as golite and chrysotile; Smectite clay minerals such as montmorillonite, biderite, nontronite, saponite, hectolite, soconite and stebunsite; vermiculite clay minerals such as vermiculite; white mica, gold mica, Mica or mica clay minerals such as margarite, tetrasilic mica, teniolite; etc. may be mentioned. These inorganic layered minerals (B) are used alone or in combination of two or more. Among these inorganic layered minerals (B), smectite group clay minerals such as montmorillonite and mica group clay minerals such as water-swellable mica are particularly preferable.

The size of the inorganic layered mineral (B) is preferably such that the average particle size is 10 μm or less and the thickness is 500 nm or less. When the average particle size and the thickness are each equal to or less than the above upper limit values, the inorganic layered mineral (B) can be easily aligned uniformly in the film formed from the coating agent, and the gas barrier property and the film cohesive strength are high. Become. The average particle size of the inorganic layered mineral (B) can be measured by a laser diffraction type particle size distribution meter. The thickness of the inorganic layered mineral (B) can be measured by an atomic force microscope (AFM).

The inorganic layered mineral (B) preferably contains at least a water-swellable synthetic mica.
The water-swellable synthetic mica has high compatibility with the water-soluble polymer (A) and the water-based polyurethane resin (C), and has less impurities than the natural mica. Therefore, when water-swellable synthetic mica is used as the inorganic layered mineral (B), it is easy to suppress a decrease in oxygen barrier property and a decrease in film cohesive force due to impurities. Further, since the water-swellable synthetic mica has a fluorine atom in the crystal structure, it also contributes to suppressing the humidity dependence of the oxygen barrier property of the film formed from the coating agent to be low. In addition, the water-swellable synthetic mica has a higher aspect ratio than other water-swellable inorganic layered minerals, so that the maze effect works more effectively and the oxygen barrier of the film formed from the coating agent. Contributes to the particularly high expression of sex.

The average particle size of the water-swellable synthetic mica is preferably 1 to 10 μm, more preferably 3 to 8 μm, for example. When the average particle size of the water-swellable synthetic mica is equal to or higher than the above lower limit, the oxygen barrier property is likely to be improved. When the average particle size of the water-swellable synthetic mica is not more than the above upper limit, it is easy to align uniformly in the film.
The thickness of the water-swellable synthetic mica is, for example, preferably 10 to 100 nm, more preferably 10 to 80 nm. When the thickness of the water-swellable synthetic mica is at least the above lower limit, the oxygen barrier property is likely to be improved. When the thickness of the water-swellable synthetic mica is not more than the above upper limit value, it is easy to align uniformly in the film.
The content of the water-swellable synthetic mica is, for example, preferably 50% by mass or more, more preferably 70% by mass or more, and may be 100% by mass with respect to the total mass of the inorganic layered mineral (B).

<Aqueous polyurethane resin (C)>
The aqueous polyurethane resin (C) is used to impart flexibility and gas barrier properties, particularly oxygen barrier properties, to the film. Further, since the coating agent contains the aqueous polyurethane resin (C), the wettability of the coating agent to the resin base material and the adhesive strength of the film formed from the coating agent to the resin base material are likely to be excellent.

The aqueous polyurethane resin (C) preferably contains an acid group-containing polyurethane resin (hereinafter, also referred to as “acid group-containing polyurethane resin”) and a polyamine compound. Since the aqueous polyurethane resin (C) contains the acid group-containing polyurethane resin and the polyamine compound, good oxygen barrier properties are likely to be exhibited even in a high humidity atmosphere.
In an aqueous polyurethane resin containing an acid group-containing polyurethane resin and a polyamine compound, gas barrier properties are exhibited by binding the acid group of the acid group-containing polyurethane resin and the polyamine compound as a cross-linking agent. The bond between the acid group of the acid group-containing polyurethane resin and the polyamine compound may be an ionic bond (for example, an ionic bond between a carboxyl group and a tertiary amino group) or a covalent bond (for example, an amide bond). It may be.

Since the acid group-containing polyurethane resin constituting the aqueous polyurethane resin (C) has an acid group, it has anionic and self-emulsifying properties, and is also referred to as an anionic self-emulsifying polyurethane resin. Examples of the acid group include a carboxyl group and a sulfonic acid group. The acid group may be located at the end or side chain of the polyurethane resin, but is preferably located at least in the side chain. This acid group can usually be neutralized with a neutralizing agent (base), and may form a salt with the base. The acid group can be bonded to the amino group (imino group or tertiary nitrogen atom) of the polyamine compound constituting the aqueous polyurethane resin (C).

The acid value of the acid group-containing polyurethane resin can be selected within a range in which water solubility or water dispersibility can be imparted. The acid value of the acid group-containing polyurethane resin is preferably 5 to 100 mgKOH / g, more preferably 10 to 70 mgKOH / g, still more preferably 15 to 60 mgKOH / g. When the acid value of the acid group-containing polyurethane resin is at least the above lower limit value, it is easy to improve the uniform dispersibility between the aqueous polyurethane resin (C) and other materials and the dispersion stability of the coating agent. When the acid value of the acid group-containing polyurethane resin is not more than the above upper limit value, it is easy to suppress a decrease in water resistance of the film and a decrease in oxygen barrier property. The acid value of the acid group-containing polyurethane resin can be measured by the method described in JIS K 0070.

The total (total concentration) of the urethane group concentration and the urea group (urea group) concentration of the acid group-containing polyurethane resin is preferably 15% by mass or more, more preferably 20 to 60% by mass, from the viewpoint of oxygen barrier properties. When the total concentration is equal to or higher than the above lower limit value, the oxygen barrier property can be more easily improved. When the total concentration is not more than the above upper limit value, it is easy to prevent the film from becoming rigid and brittle.
The urethane group concentration means the ratio of the molecular weight (59 g / equivalent) of the urethane group to the molecular weight of the repeating constituent unit of the polyurethane resin. The urea group concentration means the ratio of the molecular weight of the urea group (primary amino group (amino group): 58 g / equivalent, secondary amino group (imino group): 57 g / equivalent) to the molecular weight of the repeating constituent unit of the polyurethane resin. To do.
When two or more kinds of mixtures are used as the polyurethane resin, the urethane group concentration and the urea group concentration can be calculated based on the preparation base of the reaction component, that is, the usage ratio of each component.

The acid group-containing polyurethane resin preferably has at least a rigid unit (a unit composed of a hydrocarbon ring) and a short chain unit (for example, a unit composed of a hydrocarbon chain). That is, the repeating constituent unit of the acid group-containing polyurethane resin is derived from a polyisocyanate component, a polyhydroxyic acid component, a polyol component and a chain extender component (particularly, at least a polyisocyanate component), and is a hydrocarbon ring (aromatic and non-aromatic). It preferably contains at least one of the aromatic hydrocarbon rings).
The ratio of the unit composed of the hydrocarbon ring to the repeating constituent unit of the acid group-containing polyurethane resin is preferably 10 to 70% by mass, more preferably 15 to 65% by mass, still more preferably 20 to 60% by mass. When the ratio of the unit composed of the hydrocarbon ring is at least the above lower limit value, it is easy to suppress the decrease in oxygen barrier property. When the ratio of the unit composed of the hydrocarbon ring is not more than the above upper limit value, it is easy to prevent the film from becoming rigid and brittle.

The number average molecular weight of the acid group-containing polyurethane resin can be appropriately selected, but is preferably 800 to 1,000,000, more preferably 800 to 200,000, still more preferably 800 to 100,000. When the number average molecular weight of the acid group-containing polyurethane resin is at least the above lower limit value, it is easy to suppress a decrease in oxygen barrier property. When the number average molecular weight of the acid group-containing polyurethane resin is not more than the above upper limit value, it is easy to suppress an increase in the viscosity of the coating agent.
The number average molecular weight of the acid group-containing polyurethane resin is a standard polystyrene-equivalent value measured by gel permeation chromatography (GPC).

The acid group-containing polyurethane resin may be crystalline in order to enhance the oxygen barrier property. The glass transition temperature of the acid group-containing polyurethane resin is preferably 100 to 200 ° C., more preferably 110 to 180 ° C., and even more preferably 120 to 150 ° C. When the glass transition temperature of the acid group-containing polyurethane resin is at least the above lower limit value, it is easy to suppress a decrease in oxygen barrier property. The glass transition temperature of the acid group-containing polyurethane resin is typically not more than or equal to the above upper limit.
The glass transition temperature of the acid group-containing polyurethane resin can be measured by differential scanning calorimetry (DSC).

The aqueous polyurethane resin (C) preferably contains a neutralizing agent and is formed in a state in which the acid group-containing polyurethane resin is dissolved or dispersed in an aqueous medium.
The aqueous medium is as described above.
The aqueous polyurethane resin (C) may be in the form of an aqueous solution in which an acid group-containing polyurethane resin is dissolved in an aqueous medium, or may be in the form of an aqueous dispersion in which an acid group-containing polyurethane resin is dispersed in an aqueous medium.

In the aqueous dispersion, the average particle size of the dispersed particles (polyurethane resin particles) is not particularly limited, and is preferably 20 to 500 nm, more preferably 25 to 300 nm, and even more preferably 30 to 200 nm. When the average particle size of the dispersed particles is at least the above lower limit value, the oxygen barrier property is likely to be improved. When the average particle size of the dispersed particles is not more than the above upper limit value, it is easy to suppress the decrease in uniform dispersibility between the dispersed particles and other materials and the dispersion stability of the coating agent, and it is easy to suppress the decrease in oxygen barrier property.
The average particle size of the dispersed particles is measured with a concentrated particle size analyzer (FPAR-10 manufactured by Otsuka Electronics Co., Ltd.) with a solid content concentration of 0.03 to 0.3% by mass (diluted with water). The value.

The polyamine compound constituting the aqueous polyurethane resin (C) is not particularly limited as long as it can bond with an acid group and improve the oxygen barrier property, and various polyamine compounds having two or more basic nitrogen atoms are used. Compounds are used. The basic nitrogen atom is a nitrogen atom that can be bonded to an acid group of an acid group-containing polyurethane resin. For example, a nitrogen atom in an amino group such as a primary amino group, a secondary amino group, or a tertiary amino group is used. Can be mentioned.
As the polyamine compound, a polyamine compound having at least one amino group selected from the group consisting of a primary amino group, a secondary amino group and a tertiary amino group is preferable.

Specific examples of the polyamine compound include alkylenediamines, polyalkylene polyamines, and silicon compounds having a plurality of basic nitrogen atoms. Examples of alkylenediamines include alkylenediamines having 2 to 10 carbon atoms such as ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butanediamine, and 1,6-hexamethylenediamine. Be done. Examples of polyalkylene polyamines include tetraalkylene polyamines. Examples of the silicon compound having a plurality of basic nitrogen atoms (including nitrogen atoms such as amino groups) include 2- [N- (2-aminoethyl) amino] ethyltrimethoxysilane and 3- [N- (2- (2-). Examples thereof include a silane coupling agent having a plurality of basic nitrogen atoms such as aminoethyl) amino] propyltriethoxysilane.

The amine value of the polyamine compound is preferably 100 to 1900 mgKOH / g, more preferably 150 to 1900 mgKOH / g, further preferably 200 to 1900 mgKOH / g, particularly preferably 200 to 1700 mgKOH / g, and most preferably 300 to 1500 mgKOH / g. .. When the amine value of the polyamine compound is at least the above lower limit value, the oxygen barrier property can be more easily improved. When the amine value of the polyamine compound is not more than the above upper limit value, the aqueous dispersion stability of the aqueous polyurethane resin (C) is excellent.

The amine value of the polyamine compound can be measured by the following method.
Weigh 0.5 to 2 g of the sample (sample amount Sg). Add 30 g of ethanol to the precisely weighed sample and dissolve. Bromophenol blue is added to the obtained solution as an indicator, and titration is performed with a 0.2 mol / L ethanolic hydrochloric acid solution (titer f). With the point where the color of the solution changes from green to yellow as the end point, the titration amount (AmL) at this time is measured, and the amine titer is calculated using the following formula 1.
Calculation formula 1: Amine value = A × f × 0.2 × 56.108 / S [mgKOH / g]

In the aqueous polyurethane resin (C), the content of the polyamine compound is such that the molar ratio (acid group / basic nitrogen atom) of the acid group of the acid group-containing polyurethane resin to the basic nitrogen atom of the polyamine compound is 10/1 to 1 to 1. The amount to be 0.1 / 1 is preferable, and the amount to be 5/1 to 0.2 / 1 is more preferable. When the acid group / basic nitrogen atom is within the above numerical range, the cross-linking reaction between the acid group of the acid group-containing polyurethane and the polyamine compound occurs appropriately, and a good oxygen barrier property is exhibited in the film even in a high humidity atmosphere. Cheap.

As the aqueous polyurethane resin (C), a commercially available one may be used, or one manufactured by a known production method may be used. The method for producing the aqueous polyurethane resin (C) is not particularly limited, and ordinary polyurethane resin aqueous techniques such as an acetone method and a prepolymer method are used. In the urethanization reaction, a urethanization catalyst such as an amine-based catalyst, a tin-based catalyst, or a lead-based catalyst may be used, if necessary.
For example, in an inert organic solvent such as ketones such as acetone, ethers such as tetrahydrofuran, and nitriles such as acetonitrile, a polyisocyanate compound, a polyhydroxyic acid, and, if necessary, a polyol component and a chain extender component. An aqueous polyurethane resin (C) can be prepared by reacting with at least one of them. More specifically, a pre-isocyanate compound having an isocyanate group at the terminal is reacted by reacting a polyisocyanate compound, a polyhydroxy acid, and a polyol component in an inert organic solvent (particularly, a hydrophilic or water-soluble organic solvent). A polymer is produced, neutralized with a neutralizing agent, dissolved or dispersed in an aqueous medium, and then a chain extender component is added and reacted to remove an organic solvent to remove an aqueous solution or water of an acid group-containing polyurethane resin. Dispersions can be prepared. An aqueous polyurethane resin (C) in the form of an aqueous solution or an aqueous dispersion is prepared by adding a polyamine compound to the aqueous solution or aqueous dispersion of the acid group-containing polyurethane resin thus obtained and heating as necessary. it can. When heating, the heating temperature is preferably 30 to 60 ° C.

<Curing agent (D)>
The curing agent (D) has reactivity with components in the coating agent (water-soluble polymer (A), inorganic layered mineral (B), aqueous polyurethane resin (C), etc.). When the coating agent contains the curing agent (D), it is possible to suppress the elution of organic substances that easily elute into water in the film and reduce the consumption of potassium permanganate. In addition, the adhesion between the film and the resin base material can be further strengthened.

The curing agent (D) is not particularly limited as long as it has reactivity with the components in the coating agent, but an isocyanate compound, a silane coupling agent, or an epoxy compound is preferable. Of these, isocyanate compounds are preferable in terms of adhesion to the resin substrate.

As the isocyanate compound, any compound having an isocyanate group (-NCO) can be used without particular limitation. The isocyanate group reacts with the hydroxyl group of the water-soluble polymer (A) or the aqueous polyurethane resin (C) to form a strong bond. Therefore, when the coating agent contains an isocyanate compound, it is possible to increase the cohesive strength of the film, improve the adhesion to the resin base material and other base materials, and increase the practical strength as a packaging material.

The isocyanate compound is preferably a polyisocyanate compound having at least two isocyanate groups in the molecule, for example, phenylenediocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated. Examples thereof include organic polyisocyanate compounds such as diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hydrogenated toluene diisocyanate or tetramethylene xylylene diisocyanate, and derivatives of these organic polyisocyanate compounds.

As the isocyanate compound, an isocyanate compound having dispersibility in water (water-dispersible isocyanate compound) is preferable. Examples of the water-dispersible isocyanate compound include (1) an isocyanate obtained by modifying some of the isocyanate groups of the organic polyisocyanate compound with a hydrophilic group such as a polyethylene oxide, a carboxy group or a sulfonic acid group to form a self-emulsifying type. Compounds, (2) isocyanate compounds obtained by forcibly emulsifying the organic polyisocyanate compound with a surfactant or the like to make it water-dispersible, (3) various prepolymers derived from the organic polyisocyanate compound, (4) the above. Examples include compounds in which some of the isocyanate groups in the organic polyisocyanate are blocked with a blocking agent such as alcohols, phenols, oximes, mercaptans, amides, imides or lactams, so-called blocked polyisocyanate compounds. Be done.
Any one of these isocyanate compounds may be used alone, or two or more thereof may be used in combination.

As the silane coupling agent, commonly used ones can be used, and examples thereof include compounds having an alkoxy group bonded to a silicon atom and an organic reactive group. The alkoxy group of the silane coupling agent is hydrolyzed to generate a silanol group, and exerts an interaction effect such as reaction with an inorganic compound and adsorption. In the coating agent, the cohesive strength of the film is improved by the interaction between the inorganic layered mineral (B) and the silane coupling agent. Further, when the organic reactive group of the silane coupling agent reacts with an organic component such as a water-soluble polymer (A) and an aqueous polyurethane resin (C), the adhesion strength of the film to the resin base material is improved. Therefore, when the coating agent contains a silane coupling agent, the cohesive strength of the film can be increased, the adhesion to the resin base material and other base materials can be improved, and the practical strength as a packaging material can be increased.

Examples of the silane coupling agent include compounds represented by RSiX ₃ (where R is an organic reactive group and X is an alkoxy group). As the organic reactive group, those having reactivity with the components in the coating agent are preferable, and for example, a group having an amino group, a (meth) acryloyl group, an epoxy group, a vinyl group, a mercapto group, an isocyanate group or an isocyanurate group is preferable. Can be mentioned. The (meth) acryloyl group represents both an acryloyl group and a meta-acryloyl group. Examples of the alkoxy group include a methoxy group and an ethoxy group.

Examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-2 (aminoethyl) -3-aminopropyltrimethoxysilane as silane coupling agents having an amino group. , N-2 (aminoethyl) -3-aminopropylmethyldimethoxysilane and the like. Examples of the silane coupling agent having a (meth) acryloyl group include 3-acryloxypropyltrimethoxysilane. As a silane coupling agent having an epoxy group, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxy Examples thereof include propylmethyldimethoxysilane and 3-glycidoxypropylethyldiethoxysilane. Examples of the silane coupling agent having a vinyl group include vinyltrimethoxysilane and vinyltriethoxysilane. Examples of the silane coupling agent having a mercapto group include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropylmethyldimethoxysilane. Examples of the silane coupling agent having an isocyanate group include 3-isocyanatepropyltriethoxysilane. Examples of the silane coupling agent having an isocyanurate group include tris (trimethoxysilylpropyl) isocyanurate and the like. Any one of these silane coupling agents may be used alone, or two or more thereof may be used in combination.
The silane coupling agent preferably has an epoxy group. The epoxy group has good reactivity with the hydroxyl groups of the water-soluble polymer (A) and the aqueous polyurethane resin (C). The epoxy group reacts with the hydroxyl groups of the water-soluble polymer (A) and the aqueous polyurethane resin (C) to form a strong bond, so that the adhesion strength of the film to the resin substrate is particularly strong.

As the epoxy compound, any compound having an epoxy group can be used without particular limitation. As described above, the epoxy group reacts with the hydroxyl group of the water-soluble polymer (A) or the aqueous polyurethane resin (C) to form a strong bond. Therefore, when the coating agent contains an epoxy compound, it is possible to increase the cohesive strength of the film, improve the adhesion to the resin base material and other base materials, and increase the practical strength as a packaging material. Further, since the reaction rate is within an appropriate region, the usable period of the coating agent after the addition of the curing agent (D) is long.

The epoxy compound may be a monofunctional epoxy compound having one epoxy group, or a polyfunctional epoxy compound having two or more epoxy groups. Moreover, you may use these in combination.
Examples of the monofunctional epoxy compound include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropyl. Examples thereof include silane coupling agents having an epoxy group such as methyldimethoxysilane and 3-glycidoxypropylethyldiethoxysilane. Examples of the monofunctional epoxy compound other than the silane coupling agent having an epoxy group include phenylglycidyl ether, 2-ethylhexyl glycidyl ether, ethyldiethylene glycol glycidyl ether, dicyclopentadiene glycidyl ether, 2-hydroxyethyl glycidyl ether and the like. Any one of these monofunctional epoxy compounds may be used alone, or two or more thereof may be used in combination.

Examples of the polyfunctional epoxy compound include hydroquinone diglycidyl ether, resorcinol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, cyclohexenediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, and dicyclopentadienediol diglycidyl. Examples thereof include ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylpropan triglycidyl ether, pentaerythritol tetraglycidyl ether, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and epoxidized polybutadiene. Any one of these polyfunctional epoxy compounds may be used alone, or two or more thereof may be used in combination.

As the epoxy compound, a silane coupling agent having an epoxy group or a polyfunctional epoxy compound is preferable from the viewpoint of being able to form a complicated and strong crosslinked structure. As the polyfunctional epoxy compound, a trifunctional or higher functional epoxy compound is preferable from the viewpoint that a more complicated crosslinked structure can be formed.

Examples of other components include additives such as antioxidants, weather resistant agents, heat stabilizers, lubricants, crystal nucleating agents, ultraviolet absorbers, plasticizers, antistatic agents, colorants, fillers, and surfactants. Be done.

The preferred range of the solid content of each of the water-soluble polymer (A), inorganic layered mineral (B), aqueous polyurethane resin (C), and curing agent (D) with respect to the mass of the solid content of the coating agent is the film. It is the same as the preferable range of the content of each component with respect to the total mass.
The preferable range of the mass ratio of the aqueous polyurethane resin (C) to the water-soluble polymer (A) in the coating agent in terms of solid content is the same as the above-mentioned preferable range of the ratio (C) / (A).
The preferred range of the mass ratio of the curing agent (D) to the water-soluble polymer (A) in the coating agent in terms of solid content is the same as the preferred range of the (D) / (A) ratio described above.
The preferable range of the total content of the water-soluble polymer (A), the inorganic layered mineral (B), the aqueous polyurethane resin (C) and the curing agent (D) with respect to the mass of the solid content of the coating agent is the total amount of the film. It is the same as the preferable range of the total content of the water-soluble polymer (A), the inorganic layered mineral (B), the aqueous polyurethane resin (C), and the curing agent (D) with respect to the mass.

The viscosity of the coating agent at 23 ° C. is preferably 10 to 80 mPa · s, more preferably 10 to 50 mPa · s.
The viscosity of the coating agent is a value measured by an E-type viscometer.

The coating agent of the present embodiment requires a water-soluble polymer (A), an inorganic layered mineral (B), an aqueous polyurethane resin (C), a curing agent (D), and if necessary, other components. It can be prepared by mixing an additional aqueous medium or the like according to the above. The mixing order of each component is not particularly limited. The curing agent may be mixed with other components or added immediately before coating on the resin substrate.

(Manufacturing method of gas barrier film)
The gas barrier film of the present embodiment can be produced, for example, by forming a film on at least one surface of a resin base material.
As the resin base material, a commercially available product may be used, or a product manufactured by a known method may be used.
As described above, the film is obtained by forming a coating film made of a coating agent on at least one surface of the resin base material by the wet coating method and drying the coating film.
As the wet coating method, known wet coating methods such as a roll coating method, a gravure coating method, a reverse coating method, a die coating method, a screen printing method, and a spray coating method can be used.
As a method for drying the coating film made of the coating agent, known drying methods such as hot air drying, hot roll drying, and infrared irradiation can be used. The drying temperature of the coating film is preferably, for example, 50 to 200 ° C. The drying time varies depending on the thickness of the coating film, the drying temperature, and the like, but is preferably 1 second to 5 minutes, for example.

(Action effect)
The gas barrier film according to the present embodiment is a film formed from a coating agent containing a water-soluble polymer (A), an inorganic layered mineral (B), an aqueous polyurethane resin (C), and a cured product (D). Therefore, it exhibits excellent oxygen barrier properties even in a high humidity atmosphere. In addition, the adhesion between the resin base material and the film is excellent. Furthermore, since the consumption of potassium permanganate measured by the above-mentioned measuring method is 10.0 μg / mL or less, the elution of organic substances that easily elute into water in the film is suppressed. Therefore, it can be used as a packaging material even in a form in which the film comes into direct contact with a content containing water (food, etc.).

Although the present invention has been described above with reference to embodiments, the present invention is not limited to the above-described embodiments. Each configuration and a combination thereof in the above-described embodiment are examples, and the configuration can be added, omitted, replaced, or otherwise changed without departing from the spirit of the present invention.

The gas barrier film of the present invention further has a printing layer, an anchor coat layer, an overcoat layer, a light-shielding layer, an adhesive layer, a heat-sealing heat-sealing layer, and other functional layers, if necessary. You may.
Since the gas barrier film has a heat-sealing layer, the gas barrier film can be sealed by a heat seal. When the gas barrier film has a heat-sealing heat-sealing layer, the heat-sealing layer is preferably located on at least one outermost surface of the gas barrier film.
The heat-sealing layer is formed by, for example, a known dry laminating method using a known adhesive such as polyurethane, polyester, or polyether on a laminate in which a film is provided on at least one surface of a resin base material. It can be laminated by an extrusion laminating method or the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

(Material used)
<Resin base material>
Biaxially stretched polypropylene film (trade name: VPH2011, thickness 20 μm, AB agent average particle size 2 μm, AB agent content 0.2% by mass, manufactured by AJ Plast).

<Water-soluble polymer (A)>
(A1): Polyvinyl alcohol having a degree of saponification of 98 to 99% and a degree of polymerization of 500 (Poval PVA-105, manufactured by Kuraray Co., Ltd.).
(A2): Polyvinyl alcohol having a degree of saponification of 98 to 99% and a degree of polymerization of 1000 (Poval PVA-110, manufactured by Kuraray).

<Inorganic layered mineral (B)>
(B1): Water-swellable synthetic mica (Somasif (registered trademark) MEB-3, manufactured by CO-OP CHEMICAL CO., LTD.).
(B2): Purified montmorillonite (Kunipia-F, manufactured by Kunimine Industries, Ltd.).

<Aqueous polyurethane resin (C)>
(C1): An aqueous polyurethane resin containing an acid group-containing polyurethane resin and a polyamine compound (Takelac WPB-341, an aqueous polyurethane dispersion "Takelac (registered trademark) WPB-341" manufactured by Mitsui Chemicals, Inc.).

<Curing agent (D)>
(D1): Water-soluble polyisocyanate (Takenate WD-725, manufactured by Mitsui Chemicals, Inc.).

(Examples 1 to 10, Comparative Examples 1 to 4)
The component (A), the component (B) and the component (C) are blended in the solid content mixing ratio shown in Table 1, heated at 80 ° C., mixed, and then cooled to room temperature, and 10% by mass in the solvent is added. Isopropanol was diluted with ion-exchanged water and isopropanol so that the final solid content concentration was 9%, and the component (D) was added at the solid content ratio shown in Table 1 immediately before coating to prepare a coating agent. ..

The above coating agent is applied to one surface of the resin base material using a gravure coater, passed through an oven at 90 ° C. for 10 seconds to dry, and a film having the thickness shown in Table 1 is formed to form a gas barrier. I got a sex film.

(Oxygen permeability)
For the gas barrier film of each example, oxygen permeability (cc / (m2.)) Was used in an atmosphere of 30 ° C. and 60% RH using an oxygen permeability measuring device (trade name: OXTRAN-2 / 20, manufactured by MOCON). day · atm))) was measured. The measurement results are shown in Table 1.

(Potassium permanganate consumption)
For the gas barrier film of each example, the potassium permanganate consumption was measured four times by the above-mentioned measuring method, and the average value was taken as the potassium permanganate consumption. The measurement results are shown in Table 1.

The gas barrier films of Examples 1 to 10 had a potassium permanganate consumption of 10.0 μg / mL or less, and the elution of organic substances was suppressed. In addition, the value of oxygen permeability under a 30 ° C. and 60% RH atmosphere was as low as 2.0 cm ³ / (m ² · day · atm) or less, and the oxygen barrier property was also excellent.
On the other hand, the gas barrier films of Comparative Examples 1 to 4 had a potassium permanganate consumption of more than 10.0 μg / mL, or an oxygen permeability value of 2.0 cccm ³ / (m ²⁾ under a 30 ° C. and 60% RH atmosphere.・ Day ・ atm) was exceeded, and it was not possible to combine low elution of organic substances with excellent oxygen barrier properties.

The gas barrier film of the present invention has various contents such as foods that dislike moisture and oxygen (dried foods, confectionery, bread, delicacies, etc.), disposable body warmers, pharmaceuticals (tablets, powdered medicines, poultices, patches, etc.). Can be used as a packaging material for.
The gas barrier film of the present invention is useful as a packaging material for contents containing water (for example, vegetables and fruits).

1 Gas barrier film, 2 Gas barrier film, 3 Resin base material, 5 film

Claims (6)

A resin base material and a film located in contact with at least one surface of the resin base material are provided.
The film is formed of a coating agent containing a water-soluble polymer (A), an inorganic layered mineral (B), an aqueous polyurethane resin (C), and a curing agent (D).
The potassium permanganate consumption of the test solution obtained by bringing 2 mL of distilled water per 1 cm ² of the surface area of the film into contact with the film and holding it at 60 ° C. for 30 minutes is 10.0 μg / mL or less.
Gas barrier film 30 ° C., the oxygen permeability under a relative humidity of ^60%, and wherein the at ^{2.0cm 3 / (m 2 · day} · atm) or less. The gas barrier film according to claim 1, wherein the total mass of the water-soluble polymer (A) and the water-based polyurethane resin (C) per unit area of the film is 0.47 g / m ² or less. The water-soluble polymer (A) is 25 to 80% by mass, the inorganic layered mineral (B) is 8 to 20% by mass, and the aqueous polyurethane resin (C) is 5 to 60% by mass with respect to the total mass of the film. The gas barrier film according to claim 1 or 2, wherein the curing agent (D) is 5 to 20% by mass. The gas barrier film according to any one of claims 1 to 3, wherein the film has a thickness of 0.32 to 0.55 μm. The invention according to any one of claims 1 to 4, wherein the mass ratio ((D) / (A) ratio) of the curing agent (D) to the water-soluble polymer (A) is 10/90 to 30/70. Gas barrier film. The gas barrier film according to any one of claims 1 to 5, wherein the resin base material is a polyolefin-based resin film, a polyester-based resin film, or a polyamide-based resin film.

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