JP6524781B2 - Coating agent and gas barrier film - Google Patents

Description

  The present invention relates to a coating agent and a gas barrier film.

Packaging materials used for packaging food, medicines, etc. contain ingress of gas that alters water vapor, oxygen, and other contents in order to suppress deterioration and decay of the contents, etc., and retain their functions and properties. Is required to have the property of blocking
Therefore, those having a gas barrier layer are conventionally used for these packaging materials.

Heretofore, the gas barrier layer has been provided on a substrate such as a film or paper by a sputtering method, a vapor deposition method, a wet coating method, a printing method or the like.
Further, as the gas barrier layer, metal foil or metal vapor deposition film made of metal such as aluminum, water-soluble polymer such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer, resin film made of resin such as polyvinylidene chloride A composite film of an organic polymer and an inorganic layered mineral is used (see, for example, Patent Documents 1 to 6).

However, although metal foils and metal deposition films are excellent in gas barrier properties, they are opaque and can not confirm the contents, and because they are poor in stretchability, cracks occur at a few percent elongation, and the gas barrier properties deteriorate. There were various problems, such as the need to treat as incombustible material at the time of later disposal.
A resin film made of a water-soluble polymer such as polyvinyl alcohol or ethylene-vinyl alcohol copolymer exhibits high gas barrier properties under a low humidity atmosphere. However, the gas barrier properties are dependent on humidity, and the gas barrier properties decrease with the increase in humidity, and the gas barrier properties are lost under high humidity atmosphere, for example, at a humidity of 70% RH or more. was there.
A resin film made of polyvinylidene chloride has low humidity dependency and exhibits excellent gas barrier properties, but since it contains chlorine, it may be a source of generation of harmful substances such as dioxin at the time of waste treatment and the like.
A composite film of a water-soluble polymer and an inorganic layered mineral is superior in gas barrier properties under a high humidity atmosphere as compared to a resin film made of a water-soluble polymer. Moreover, it is excellent in transparency compared with metal foil and metal vapor deposition film. However, its transparency is inferior to that of resin films such as polyvinylidene chloride.

Japanese Patent Laid-Open No. 2002-321301 JP 2001-287294 A Unexamined-Japanese-Patent No. 11-165369 gazette JP-A-6-93133 JP-A-9-150484 Patent No. 3780741

  The present invention has been made in view of the above circumstances, and provides a coating agent which exhibits high gas barrier properties even in a high humidity atmosphere and can form a gas barrier layer excellent in transparency, and a gas barrier film using the same. The purpose is to

The present invention has the following aspects.
<1> An aqueous dispersion in which an aqueous polyurethane resin (A) containing an acid group-containing polyurethane resin and a polyamine compound is dispersed in an aqueous medium, a water-soluble polymer (B), and an inorganic layered mineral (C) ,
A coating agent characterized in that the average particle diameter of the aqueous polyurethane resin (A) is 100 nm or less.
The ratio of the aqueous polyurethane resin (A) to the total solid content is 5 to 60% by mass, and the ratio of the water-soluble polymer (B) is 25 to 80% by mass, based on the inorganic layered mineral (C) The coating agent as described in <1> whose ratio is 8-20 mass%.
<3> base film made of plastic material,
A gas barrier layer formed of the coating agent according to <1> or <2>, laminated on at least one surface of the base film;
A gas barrier film characterized by comprising:

  According to the present invention, it is possible to provide a coating agent which exhibits high gas barrier properties even in a high humidity atmosphere and can form a gas barrier layer excellent in transparency, and a gas barrier film using the same.

  Hereinafter, embodiments of the coating agent and the gas barrier film of the present invention will be described. The present embodiment is specifically described for better understanding of the spirit of the invention, and does not limit the present invention unless otherwise specified.

<Coating agent>
The coating agent of the present invention comprises an aqueous dispersion in which an aqueous polyurethane resin (A) is dispersed in an aqueous medium, a water-soluble polymer (B), and an inorganic layered mineral (C).

"Aqueous dispersion of aqueous polyurethane resin (A)"
The aqueous polyurethane resin (A) contains a polyurethane resin having an acid group (hereinafter, also referred to as "acid group-containing polyurethane resin") and a polyamine compound.
The aqueous polyurethane resin (A) does not dissolve in an aqueous medium, but has water dispersibility dispersed in an aqueous medium. In the aqueous dispersion, particles of the aqueous polyurethane resin (A) are dispersed.

  An aqueous polyurethane resin (A) containing an acid group-containing polyurethane resin and a polyamine compound differs from a general polyurethane resin by combining a polyamine compound as a crosslinking agent with an acid group of the acid group-containing polyurethane resin It forms a rigid molecular skeleton and exhibits gas barrier properties. The dried film of the aqueous polyurethane resin (A) containing an acid group-containing polyurethane resin and a polyamine compound is insoluble in water, as with general polyurethane resins. Therefore, the gas barrier properties of the gas barrier layer formed from the coating agent of the present invention containing the aqueous polyurethane resin (A) have low humidity dependency.

The acid group of the acid group-containing polyurethane resin (anionic self-emulsifying polyurethane resin) constituting the aqueous polyurethane resin (A) is the amino group (primary amino group, first of the polyamine compounds constituting the aqueous polyurethane resin (A) It is possible to bind to a secondary amino group, a tertiary amino group etc.).
As an acid group, a carboxyl group, a sulfonic acid group, etc. are mentioned. The acid group is usually neutralized by a neutralizing agent (base), and may form a salt with the base.
The acid group may be located at the end of the acid group-containing polyurethane resin or in the side chain, but is preferably located at least in the side chain.

The acid value of the acid group-containing polyurethane resin can be selected in the range that can impart water dispersibility, but is usually 5 to 100 mg KOH / g, preferably 10 to 70 mg KOH / g, and 15 to 60 mg KOH / g. It is more preferable that it is g. When the acid value of the acid group-containing polyurethane resin is less than the lower limit of the above range, the water solubility or water dispersibility of the acid group-containing polyurethane resin becomes insufficient, and the uniform dispersion of the aqueous polyurethane resin with other materials and coating The dispersion stability of the agent may be reduced. If the acid value of the acid group-containing polyurethane resin is above the upper limit of the above range, the water resistance and gas barrier properties of the gas barrier layer formed from the coating agent may be lowered. When the acid value of the acid group-containing polyurethane resin is in the above range, it is possible to avoid the decrease in the dispersion stability and the decrease in the water resistance and the gas barrier property.
The acid value of the acid group-containing polyurethane resin is measured by a method according to JIS K 0070.

The total 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, and more preferably 20 to 60% by mass from the viewpoint of gas barrier properties. If the sum of the urethane group concentration and the urea group concentration is less than the lower limit value of the above range, the gas barrier properties of the gas barrier layer formed from the coating agent may be insufficient. If the sum of the urethane group concentration and the urea group concentration is above the upper limit value of the above range, the gas barrier layer formed from the coating agent may be rigid and fragile.
The urethane group concentration and the urea group concentration refer to the molecular weight of the urethane group (59 g / equivalent) or the molecular weight of the urea group (primary amino group (amino group): 58 g / equivalent, secondary amino acid with respect to the molecular weight of the repeating structural unit of the polyurethane resin. It means the ratio of group (imino group): 57 g / equivalent). In addition, when using 2 or more types of mixtures as an acidic radical containing polyurethane resin, a urethane group density | concentration and a urea group density | concentration can be calculated based on the preparation base of a reaction component, ie, the use ratio of each component.

The acid group-containing polyurethane resin usually 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 usually derived from a polyisocyanate component, a polyhydroxy acid component, a polyol component and a chain extender component (in particular, at least a polyisocyanate component) to form a hydrocarbon ring (aromatic compound). And at least one of non-aromatic hydrocarbon rings).
The proportion of units composed of hydrocarbon rings in repeating constituent units of the acid group-containing polyurethane resin is usually 10 to 70% by mass, preferably 15 to 65% by mass, and more preferably 20 to 60% by mass It is. If the proportion of units composed of hydrocarbon rings in the repeating constituent units of the acid group-containing polyurethane resin is less than the lower limit of the above range, the gas barrier properties of the gas barrier layer formed of the coating agent may be insufficient. . If the proportion of units composed of hydrocarbon rings in the repeating constituent units of the acid group-containing polyurethane resin is above the upper limit of the above range, the gas barrier layer formed from the coating agent may be rigid and fragile.

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, and 800 to 100,000. Is more preferred. If the number average molecular weight of the acid group-containing polyurethane resin is above the upper limit value of the above range, the viscosity of the coating agent is undesirably increased. If the number average molecular weight of the acid group-containing polyurethane resin is less than the lower limit value of the above range, the gas barrier properties of the gas barrier layer formed from the coating agent may be insufficient.
The number average molecular weight of the acid group-containing polyurethane resin is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC).

The acid group-containing polyurethane resin may be crystalline in order to enhance the gas barrier properties.
The glass transition temperature of the acid group-containing polyurethane resin is preferably 100 ° C. or more, more preferably 110 ° C. or more, and still more preferably 120 ° C. or more. If the glass transition point of the acid group-containing polyurethane resin is less than 100 ° C., the gas barrier properties of the gas barrier layer formed of the coating agent may be insufficient.
The upper limit of the glass transition point of the acid group-containing polyurethane resin is typically about 200 ° C. or less, further about 180 ° C. or less, and further about 150 ° C. or less. It is practically unlikely that the glass transition point of the acid group-containing polyurethane resin satisfying the preferable range of each of the above items becomes higher than the above upper limit value.
Therefore, 100-200 degreeC is preferable, as for the glass transition point of an acidic radical containing polyurethane resin, 110-180 degreeC is more preferable, and 120-150 degreeC is still more preferable.
The glass transition point of the acid group-containing polyurethane resin is measured by differential scanning calorimetry (DSC).

In the aqueous polyurethane resin (A), the gas barrier property is expressed by bonding the acid group of the acid group-containing polyurethane resin and the polyamine compound as the crosslinking agent.
The polyamine compound constituting the aqueous polyurethane resin (A) is not particularly limited as long as it binds to an acid group and can improve the gas barrier property, and various 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 the acid group of the acid group-containing polyurethane resin, and for example, the nitrogen atom in an amino group such as a primary amino group, a secondary amino group, or a tertiary amino group is It can be mentioned.
The bond between the polyamine compound and the acid group of the polyurethane resin may be an ionic bond (for example, an ionic bond between a tertiary amino group and a carboxyl group) or a covalent bond (for example, an amide bond) It is also good.
The polyamine compound is preferably 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.

  As a specific example of a polyamine compound, alkylene diamines, polyalkylene polyamines, etc. are mentioned, for example. Examples of the alkylene diamines include C2-10 alkylene diamines such as ethylene diamine, 1,2-propylene diamine, 1,3-propylene diamine, 1,4-butane diamine and 1,6-hexamethylene diamine. Examples of polyalkylene polyamines include tetraalkylene polyamines and silicon compounds (silane coupling agents etc.) having a plurality of basic nitrogen atoms (including nitrogen atoms such as amino groups). Examples of the silicon compound include 2- [N- (2-aminoethyl) amino] ethyltrimethoxysilane, 3- [N- (2-aminoethyl) amino] propyltriethoxysilane and the like.

The amine value of the polyamine compound is preferably 100 to 1900 mg KOH / g, more preferably 150 to 1900 mg KOH / g, still more preferably 200 to 1900 mg KOH / g, particularly preferably 200 to 1700 mg KOH / g, and most preferably 300 to 1500 mg KOH / g. . If the amine value of a polyamine compound is more than the lower limit of the said range, it is excellent in the gas barrier property of aqueous polyurethane resin (A). If the amine value of a polyamine compound is below the upper limit of the said range, it is excellent in the water dispersion stability of aqueous polyurethane resin.
The amine value of the polyamine compound is measured by the following method.
[Method of measuring amine value]
The sample is precisely weighed from 0.5 to 2 g (sample amount Sg). 30 g of neutral ethanol (BDG neutral) is added to the precisely weighed sample to dissolve it. Bromophenol blue is added to the obtained solution as an indicator, and titration is performed with 0.2 mol / L ethanolic hydrochloric acid solution (titer f). The end point is the point at which the color of the solution changes from green to yellow, and using this titration volume (AmL), the following formula 1 is used to determine the amine value.
Formula 1:
Amine value = A × f × 0.2 × 56.108 / S [mg KOH / g]

  In the aqueous polyurethane resin (A), the content of the polyamine compound is such that the molar ratio of the acid group of the acid group-containing polyurethane resin to the basic nitrogen atom of the polyamine compound (acid group / basic nitrogen atom) is 10/1 to An amount of 0.1 / 1 is preferable, and an amount of 5/1 to 0.2 / 1 is more preferable. If the acid group / basic nitrogen atom is in the above range, the crosslinking reaction between the acid group of the acid group-containing polyurethane and the polyamine compound appropriately occurs, and the film formed from the coating agent has excellent oxygen barrier properties even under high humidity atmosphere Express.

The aqueous medium in which the aqueous polyurethane resin (A) is dispersed includes water, a water-soluble or hydrophilic organic solvent, or a mixture thereof. The aqueous medium usually contains water or water as a main component. 70 mass% or more is preferable, and, as for content of the water in an aqueous medium, 80 mass% or more is more preferable.
Examples of water-soluble or hydrophilic organic solvents include alcohols such as methanol, ethanol and isopropanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; cellosolves; carbitols; nitriles such as acetonitrile and the like It can be mentioned.
The aqueous medium may or may not contain a neutralizing agent (base) that neutralizes the acid group. Usually a neutralizing agent is included.

In the aqueous dispersion, the average particle diameter of the dispersed particles, that is, the aqueous polyurethane resin (A) is 100 nm or less, preferably 80 nm or less, and more preferably 50 nm or less. If the average particle diameter of the aqueous polyurethane resin (A) is 100 nm or less, a highly transparent gas barrier layer can be obtained. This is considered to be due to the high smoothness of the surface of the coating film formed when the coating agent is applied to the substrate film and the high smoothness of the surface of the gas barrier layer.
The lower limit of the average particle size of the aqueous polyurethane resin (A) is not particularly limited from the viewpoint of transparency, but is 10 nm or more in terms of gas barrier properties of the gas barrier layer formed from the coating agent and easiness of production or acquisition preferable.
The average particle size of the aqueous polyurethane resin (A) is a concentrated particle size analyzer (FPAR-10 manufactured by Otsuka Electronics Co., Ltd.) in a solid content concentration of 0.03 to 0.3% by mass (diluted with water) Is the value to be measured.

A commercially available thing may be used for the aqueous dispersion of aqueous polyurethane resin (A), and what was manufactured by the well-known manufacturing method may be used for it.
The method for producing the aqueous dispersion of the aqueous polyurethane resin (A) is not particularly limited, and conventional aqueous polyurethane resin technology such as acetone method and prepolymer method may be used. In the urethanization reaction, if necessary, a urethanization catalyst such as an amine catalyst, a tin catalyst, or a lead catalyst may be used.
For example, in an inert organic solvent such as ketones such as acetone, ethers such as tetrahydrofuran, nitriles such as acetonitrile, and the like, a polyisocyanate compound and a polyhydroxy acid, if necessary, a polyol component and a chain extender component An acid group-containing polyurethane resin can be prepared by reacting at least one of the following: More specifically, a polyisocyanate compound, a polyhydroxy acid and a polyol component are reacted in an inert organic solvent (in particular, a hydrophilic or water-soluble organic solvent) to obtain an isocyanate group at the end. A polymer is formed, neutralized with a neutralizing agent and dispersed in an aqueous medium, and then a chain extender component is added and reacted, and an organic solvent is removed to obtain an aqueous dispersion of an acid group-containing polyurethane resin. It can be prepared.
The aqueous dispersion of the aqueous polyurethane resin (A) can be prepared by adding a polyamine compound to the aqueous dispersion of the acid group-containing polyurethane resin thus obtained and heating it as required. When heating, 30-60 degreeC of heating temperature is preferable.

"Water-soluble polymer (B)"
"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 homogeneous system. More specifically, it refers to a state in which the intermolecular force with water molecules is stronger than the intermolecular force between the molecular chains of the polymer chain, the entanglement of the polymer chains is broken, and the polymer is uniformly dispersed in water.

The water-soluble polymer (B) is not particularly limited as long as it is a compound capable of penetrating into unit crystal layers of the later-described inorganic layered mineral (C) to be coordinated (intercalated).
Specific examples of the water-soluble polymer (B) include, for example, polyvinyl alcohol resins such as polyvinyl alcohol and derivatives thereof; polyvinyl pyrrolidone, polyacrylic acid, polymethacrylic acid or esters thereof, salts and copolymers thereof, polyhydroxyl Vinyl polymers such as ethyl methacrylate and copolymers thereof; Cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; starches such as oxidized starch, etherified starch and dextrin; copolyesters containing polar groups such as sulfoisophthalic acid A urethane type polymer, or a functional group-modified polymer in which the carboxyl group of these various polymers is modified, and the like.
The water-soluble polymer (B) preferably has a degree of polymerization of 200 or more in consideration of the film cohesive strength.

The water-soluble polymer (B) contained in the coating agent may be one type or two or more types.
The water-soluble polymer (B) preferably contains at least one polyvinyl alcohol resin selected from the group consisting of polyvinyl alcohol polymers and derivatives thereof, and has a saponification degree of 95% or more and a polymerization degree of 300 or more. It is particularly preferable to include a polyvinyl alcohol resin of 300-2400 are preferable and, as for the polymerization degree of polyvinyl alcohol resin, 450-2000 are especially preferable.
The higher the degree of saponification and the degree of polymerization, the lower the hygroscopic swelling property of the polyvinyl alcohol resin. If the degree of saponification of the polyvinyl alcohol resin is less than 95% or the degree of polymerization is less than 300, sufficient gas barrier properties may not be obtained. On the other hand, when the degree of polymerization exceeds 2000, the viscosity of the coating agent is increased, and it is difficult to uniformly mix it with other components, which may lead to problems such as a decrease in gas barrier properties and adhesion strength.

"Inorganic layered mineral (C)"
"Inorganic layered mineral" refers to an inorganic compound in which ultra-thin unit crystal layers overlap to form one layered particle.
As the inorganic layered mineral (C), compounds which swell and / or cleave in water are preferable, and among these, clay compounds having a water-swelling property are particularly preferable. More specifically, the inorganic layered mineral (C) is preferably a clay compound having a property of coordinating water between very thin unit crystal layers and absorbing and / or swelling. In general, such a clay compound is a layer in which Si ⁴⁺ coordinates to O ²⁻ to form a tetrahedral structure, Al ³⁺ , Mg ²⁺ , Fe ²⁺ , Fe ^{3+ and the} like, O ²⁻ and OH ⁻ And a layer forming an octahedral structure by being coordinated with each other are bonded in a one-to-one or two-to-one relationship to form a layered structure by stacking. This clay compound may be a natural compound or a synthesized compound.

Representative examples of the inorganic layered mineral (C) include hydrous silicates such as phyllosilicate minerals, for example, kaolinite clay minerals such as halloysite, kaolinite, enderite, dickite and nacrite; Antigorite clay minerals such as gorite and chrysotile; Smectite clay minerals such as montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite and stevensite; vermiculite clay minerals such as vermiculite; muscovite, phlogopite, Examples of mica or mica group clay minerals such as margarite, tetrasilylic mica, teniolite and the like are listed. These inorganic layered minerals (C) are used singly or in combination of two or more.
Among these inorganic layered minerals (C), smectite clay minerals such as montmorillonite, and mica clay minerals such as water-swellable mica are particularly preferable.

The size of the inorganic layered mineral (C) is preferably 10 μm or less in average particle size and 500 nm or less in thickness. If the average particle size and thickness are each equal to or less than the above upper limit, the inorganic layered mineral (C) is easily aligned uniformly in the gas barrier layer formed from the coating agent, and the gas barrier property and the film cohesive strength are high It becomes.
The inorganic layered mineral (C) particularly preferably contains at least a water-swellable synthetic mica having an average particle diameter of 1 to 10 μm and a thickness of 10 to 100 nm. The water-swellable synthetic mica is highly compatible with the aqueous polyurethane resin (A) and the water-soluble polymer (B), and contains fewer impurities than natural mica. Therefore, when water-swellable synthetic mica is used as the inorganic layered mineral (C), it is difficult to cause a decrease in gas barrier properties and a decrease in film cohesion due to impurities. In addition, since water-swellable synthetic mica has a fluorine atom in the crystal structure, it also contributes to suppress the humidity dependency of the gas barrier properties of the gas barrier layer formed from the coating agent to a low level. In addition, since water-swellable synthetic mica has a high aspect ratio compared to other water-swellable inorganic layered minerals, the maze effect works more effectively, and the gas barrier layer of the gas barrier layer formed from the coating agent Sex contributes especially to high expression.

The coating agent of the present invention may further contain various additives as needed, as long as the gas barrier properties and the strength as a packaging material are not impaired.
Additives include, for example, reactive curing agents such as polyisocyanates, carbodiimides, epoxy compounds, oxazolidone compounds, aziridine compounds, etc., antioxidants, weathering agents, heat stabilizers, lubricants, crystal nucleating agents, UV absorbers, plastics Agents, antistatic agents, colorants, fillers, surfactants, silane coupling agents and the like.

  The coating agent of the present invention may further contain an aqueous medium in addition to the aqueous medium contained in the aqueous dispersion of the aqueous polyurethane resin (A) to adjust the solid content concentration and the like. Examples of the aqueous medium include the same as described above.

"Content ratio of each component"
In the coating agent of the present invention, the ratio of the aqueous polyurethane resin (A) to the total solid content is preferably 5 to 60% by mass, more preferably 5 to 55% by mass, and still more preferably 5 to 50% by mass. 5 to 45% by mass is particularly preferred.
When the proportion of the aqueous polyurethane resin (A) is less than the lower limit of the above range, the wettability of the coating agent to the base film and the adhesion of the gas barrier layer formed from the coating agent to the base film are insufficient May be If the ratio of the aqueous polyurethane resin (A) exceeds the upper limit of the above range, the gas barrier layer formed of the coating agent may have a decrease in film cohesive strength and deterioration in haze with the passage of time. When the film cohesive strength is reduced, the laminate strength is reduced when another substrate is laminated on the gas barrier layer.

The ratio of the water-soluble polymer (B) to the total solid content is preferably 25 to 80% by mass, more preferably 30 to 80% by mass, still more preferably 30 to 75% by mass, and 35 to 75% by mass Particularly preferred.
If the ratio of the water-soluble polymer (B) is equal to or more than the lower limit value of the above range, a gas barrier film with little deterioration in laminate strength with time and a low haze can be obtained. It is considered that this is because the ratio of coordination (intercalation) of the inorganic layered mineral (C) to the unit crystal layer can be increased by increasing the ratio of the water-soluble polymer (B).
On the other hand, if the ratio of the water-soluble polymer (B) is less than the lower limit value of the above range, the gas barrier layer formed of the coating agent may be deteriorated in film cohesive strength or deterioration of haze with time. is there. In addition, when the ratio of the water-soluble polymer (B) exceeds the upper limit of the above range, the wettability of the coating agent to the base film, and the adhesion of the gas barrier layer formed from the coating agent to the base film It may be insufficient.

The ratio of the inorganic layered mineral (C) to the total solid content is preferably 8 to 20% by mass, more preferably 8 to 18% by mass, still more preferably 10 to 18% by mass, and particularly preferably 10 to 15% by mass preferable.
If the ratio of the inorganic layered mineral (C) is less than the lower limit value of the above range, the gas barrier properties of the gas barrier layer formed from the coating agent may be insufficient. When the ratio of the inorganic layered mineral (C) is above the upper limit value of the above range, the transparency of the gas barrier layer formed from the coating agent may be insufficient.

  The total content (solid content) of the aqueous polyurethane resin (A), the water-soluble polymer (B) and the inorganic layered mineral (C) in the coating agent is 85 mass with respect to the total solid content in the coating agent % Or more is preferable, and 90% by mass or more is more preferable. If the total content is at least the lower limit value, the effect of the present invention is more excellent. The upper limit is not particularly limited, and may be 100% by mass.

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

The coating agent of the present invention mixes the aqueous dispersion of the aqueous polyurethane resin (A), the water-soluble polymer (B), the inorganic layered mineral (C), and as necessary, the additive, the additional aqueous medium, etc. It can be prepared by The order of mixing of the components is not particularly limited.
When it contains a reactive curing agent as an additive, it is preferable to add the reactive curing agent just before applying to a substrate film.

"Operation effect"
In the coating agent of the present invention, an aqueous dispersion of an aqueous polyurethane resin (A) containing a polyurethane resin having an acid group and a polyamine compound, a water-soluble polymer (B), and an inorganic layered mineral (C) And since the average particle diameter of the aqueous polyurethane resin (A) is 100 nm or less, it exhibits excellent gas barrier properties even under a high humidity atmosphere, and can form a highly gas barrier layer.

According to the coating agent of the present invention, it is possible to obtain a gas barrier film having a haze of, for example, 10% or less (further, 5% or less) because the transparency of the formed gas barrier layer is high. If the haze is 10% or less, recognition of the contents is sufficiently possible when this is used as a packaging material.
The haze is a value determined by the following equation, and JIS K 7361 "Test method of total light transmittance of plastic-transparent material-first part single beam method / compensation method", JIS K 7136 "Haze of plastic-transparent material" It measures according to "how to obtain".
Haze (cloudiness) = scattered light / total light transmitted light × 100 (%)

<Gas barrier film>
The gas barrier film of the present invention comprises a base film made of a plastic material, and a gas barrier layer formed of the coating agent of the present invention laminated on at least one surface of the base film. Do.

  As a plastic material which comprises a base film, For example, Olefin-based resins, such as poly C2-10 olefins, such as polyethylene, a polypropylene, a propylene ethylene copolymer, Polyester-based resins, such as a polyethylene terephthalate and a polybutylene terephthalate; Nylon 6 Aliphatic polyamides of nylon 66, polyamide-based resins such as aromatic polyamides such as polymethaxylylene adipamide; polystyrene, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, ethylene-vinyl alcohol copolymer Etc .; acrylic resins such as homopolymers or copolymers of (meth) acrylic monomers such as polymethyl methacrylate and polyacrylonitrile; cellophane and the like. These resins may be used alone or in combination of two or more.

As a base film, the single layer film comprised with single resin, the single layer or laminated film using several resin, etc. are mentioned. Moreover, you may use the lamination | stacking base material which laminated | stacked said resin on other base materials (a metal, wood, paper, ceramics etc.).
As a base film, polyolefin resin film (especially, polypropylene film etc.), polyester resin film (especially, polyethylene terephthalate resin film), polyamide resin film (especially, nylon film) etc. are preferable.

The base film may be an unstretched film, or may be a uniaxially or biaxially oriented film.
The substrate film is corona treated, low temperature plasma, in order to improve the wettability to the coating agent and the adhesion strength to the coating on the surface on which the coating formed from the coating is laminated (the surface to which the coating agent is applied). Surface treatment such as treatment may be applied.
The base film may be subjected to anchor coating or undercoat treatment on the surface on which the film formed from the coating agent is to be laminated.

  The thickness of the substrate film is not particularly limited, and is appropriately selected depending on the price and application while taking into consideration the suitability as a packaging material and the lamination suitability of other films, but practically 3 μm to 200 μm And preferably 5 μm to 120 μm, more preferably 10 μm to 100 μm.

The gas barrier layer comprising the coating agent of the present invention is obtained by applying the coating agent of the present invention on one side (one side) or both sides of the substrate film to form a coating film comprising the coating agent, and drying the coating film It can be formed by (removing the aqueous medium).
As a method of applying the coating agent, a known wet coating method can be used. The wet coating method includes roll coating, gravure coating, reverse coating, die coating, screen printing, spray coating and the like.
As a method of drying the coating film made of the coating agent, known drying methods such as hot air drying, heat roll drying, infrared irradiation and the like can be used.

  The thickness of the gas barrier layer formed from the coating agent of the present invention is set according to the required gas barrier properties, but is preferably 0.1 μm to 5 μm, and more preferably 0.2 μm to 2 μm. Preferably, 0.3 μm to 1 μm is more preferable. If the thickness of the gas barrier layer is equal to or more than the lower limit value of the above range, sufficient gas barrier properties are easily obtained. If the thickness of the gas barrier layer is equal to or less than the upper limit value of the above range, it is easy to form a uniform coating film surface, and the drying load and the manufacturing cost can be suppressed.

The gas barrier film of the present invention further comprises, if necessary, a printing layer, an anchor coat layer, an overcoat layer, a light shielding layer, an adhesive layer, a heat sealable heat sealing layer, and other functional layers. May be
When the gas barrier film of the present invention has a heat sealable heat sealable layer, this heat seal layer is disposed on the outermost layer of at least one of the gas barrier films. When the gas barrier film has a heat fusion layer, the gas barrier film can be sealed by heat sealing.
For example, the heat-sealable layer may be a known adhesive such as polyurethane, polyester or polyether based on a laminate obtained by forming a film with the coating agent of the present invention on one side or both sides of a substrate film. It can be laminated by a known dry lamination method, extrusion lamination method or the like.

"Operation effect"
In the gas barrier film of the present invention, the gas barrier layer formed of the coating agent of the present invention is laminated on at least one side of a substrate film made of a plastic material. As described above, this gas barrier layer exhibits excellent gas barrier properties even in a high humidity atmosphere, and has high transparency.
Therefore, the gas barrier film of the present invention is excellent in gas barrier properties under a high humidity atmosphere. In addition, because the transparency of the gas barrier layer is high, when the base film is transparent, the gas barrier film may have sufficient transparency as a packaging material, for example, 10% or less as a haze value. Moreover, the base film and the layer (for example, printing layer) provided between the base film and the gas barrier layer can be visually recognized through the gas barrier layer.

Therefore, by using the gas barrier film of the present invention as a packaging material, the quality retention of the contents can be enhanced.
The gas barrier film of the present invention can be used as various packaging materials, for example, foods which are averse to moisture and oxygen such as dried foods, confections, breads and delicacies, and disposable cautery, tablets, powders or poultices・ It is useful as packaging material of medicines such as patch.
In addition, the gas barrier film of the present invention can be used in the packaging field where high gas barrier properties and transparency enabling recognition of the contents are required.

Hereinafter, the present invention will be more specifically described by way of examples and comparative examples. However, the present invention is not limited to the following examples.
The materials used in each of the following examples are shown below.

<Material used>
"Aqueous dispersion of aqueous polyurethane resin (A) containing polyurethane resin having an acid group and a polyamine compound"
(A1): aqueous dispersion obtained in Production Example 1 described later (average particle diameter of dispersed particles: 56 nm).
(A2-1) to (A2-3): Lots 1 to 3 (average particle size of dispersed particles: different in average particle size of aqueous polyurethane dispersion "Takelac (registered trademark) WPB-363" manufactured by Mitsui Chemicals, Inc .: Lot 1 72 nm, Lot 2 48 nm, Lot 3 108 nm).
(A3-1) to (A3-3): Lots 1 to 3 of the aqueous polyurethane dispersion "Takelac WPB-341" manufactured by Mitsui Chemicals, Inc., having different average particle sizes (average particle size of dispersed particles: Lot 1 is 81 nm , Lot 2 35 nm, lot 3 121 nm).

The average particle size of dispersed particles (aqueous polyurethane resin particles) in each aqueous dispersion was measured by the following procedure.
(Average particle size)
The aqueous dispersion was diluted 100 times to 1000 times with water, and the average particle size (nm) was measured using a concentrated particle size analyzer (FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.).

"Water-soluble polymer (B)"
(B1): polyvinyl alcohol having a degree of saponification of 98 to 99% and a degree of polymerization of 500 (trade name: POVAL PVA-105, manufactured by Kuraray Co., Ltd.).
(B2): polyvinyl alcohol having a degree of saponification of 98 to 99% and a degree of polymerization of 1700 (trade name: POVAL PVA-117, manufactured by Kuraray Co., Ltd.).

"Inorganic layered mineral (C)"
(C1): Water-swellable synthetic mica (trade name: Somasifu (registered trademark) MEB-3, manufactured by Coop Chemical Co., Ltd.).
(C2): Montmorillonite (trade name: Kunipia (registered trademark) -F, manufactured by Kunimin Kogyo Co., Ltd.).

"Hardener"
(D1): Isocyanate-based curing agent (trade name: Takenate (registered trademark) WD-725, manufactured by Mitsui Chemicals, Inc.).

"Base film"
OPP: A 20 μm-thick biaxially stretched surfactant-added polypropylene film (U-1 manufactured by Higashi Cello Co., Ltd.) having a corona discharge treatment on one side.
PET: 12 μm thick biaxially stretched polyethylene terephthalate film (P-60 manufactured by Toray Industries, Inc.), one side of which has been subjected to corona discharge treatment.

<Production Example 1>
45.5 g of metaxylylene diisocyanate (hereinafter sometimes referred to as "mXDI"), and 1,3-bis (isocyanatomethyl) cyclohexane (hereinafter sometimes referred to as "hydrogenated XDI"). 93.9 g, 24.8 g of ethylene glycol, 13.4 g of dimethylol propionic acid and 80.2 g of methyl ethyl ketone as a solvent are mixed and reacted at 70 ° C. for 5 hours in a nitrogen atmosphere to prepare a carboxyl group-containing urethane prepolymer solution did.
Next, this carboxyl group-containing urethane prepolymer solution was neutralized at 40 ° C. with 9.6 g of triethylamine.
The neutralized carboxyl group-containing urethane prepolymer solution is dispersed in 624.8 g of water by homodispersion, and a chain elongation reaction is performed with 21.1 g of 2-[(2-aminoethyl) amino] ethanol to remove methyl ethyl ketone By removing, an aqueous dispersion of polyurethane resin having an acid group and having a solid content of 25% by mass, an average particle diameter of 56 nm, and an acid value of 26.9 mg KOH / g was obtained.
Subsequently, the molar ratio of an acid group and a basic nitrogen atom, and an aqueous dispersion of a polyurethane resin having an acid group and γ- (2-aminoethyl) aminopropylmethyldimethoxysilane (amine value 544 mg KOH / g) as a polyamine compound Were mixed at a ratio of 1/1 to obtain an aqueous dispersion of the aqueous polyurethane resin of Production Example 1.

Examples 1 to 24 and Comparative Examples 1 to 15
First, the aqueous dispersion of the aqueous polyurethane resin (A), the water-soluble polymer (B), and the inorganic layered mineral (C) are blended according to the type and blending ratio (mass%) shown in Tables 1 to 4, After heating and mixing, the mixture was cooled to room temperature, and diluted with deionized water and isopropanol so that 10% by mass of all aqueous medium solvents was isopropanol, and the final solid concentration was 9% by mass. A curing agent was added to the obtained diluted product at a blending ratio (% by mass) shown in Tables 1 to 4 to prepare a coating agent. Here, the blending ratio is the ratio of the solid content of each component to the total solid content. The addition of the curing agent took place immediately before the subsequent application of the coating to the substrate film.

  The obtained coating agent is coated on the corona-treated surface of the base film by a gravure coating method so that the film thickness after drying becomes 0.6 μm, and dried by passing through an oven at 90 ° C. for 10 seconds. The layer was formed and the gas-barrier film of Examples 1-24 and Comparative Examples 1-15 was obtained. The base film used in each example is shown in Tables 1-4.

<Comparative Examples 16 to 17>
OPP of a base film and PET were respectively made into the gas-barrier film of Comparative Examples 16-17 as it was.

<Evaluation>
(Oxygen permeability)
With respect to the gas barrier films of Examples 1 to 24 and Comparative Examples 1 to 17, the oxygen permeability is measured in an atmosphere at 20 ° C. and 80% relative humidity using an oxygen permeability measuring device (OXTRAN-2 / 20 manufactured by MOCON) (Cm ³ / (m ² · day · MPa)) was measured. The results are shown in Tables 1 to 4.

(Haze)
The haze (%) of the gas barrier films of Examples 1 to 24 and Comparative Examples 1 to 17 was measured using a haze measuring device (NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd.). The results are shown in Tables 1 to 4.

From the results described in Tables 1 to 4, the gas barrier films of Examples 1 to 24 have an oxygen permeability of 80 cm ³ / (m ² · day · MPa) in an atmosphere at 20 ° C and a relative humidity of 80% RH. The following good gas barrier properties were obtained. This value was significantly lower than the oxygen permeability of the base film (Comparative Examples 16 and 17). Moreover, the gas-barrier films of Examples 1 to 24 had a low haze value of 10% or less, and were excellent in transparency.
On the other hand, in Comparative Examples 1 to 4 in which the average particle diameter of the aqueous polyurethane resin (A) is larger than 100 nm, the value of oxygen permeability is good, but the haze is 10% or more, and the gas barrier film Transparency was low.
In Comparative Examples 5 to 7 in which the average particle diameter of the aqueous polyurethane resin (A) is larger than 100 nm and the coating agent containing no water-soluble polymer (B) and no inorganic layered mineral (C), the haze is 10% or less Although there was an oxygen permeability value of 200 cm ³ / (m ² · day · MPa) or more, good gas barrier properties under high humidity could not be obtained.
In Comparative Examples 8 to 9 using a coating agent having an average particle diameter of the aqueous polyurethane resin (A) larger than 100 nm and not containing the water-soluble polymer (B), although the value of oxygen permeability was good, 10% or more, and the transparency of the gas barrier film was low.
In Comparative Examples 10 to 11 in which the coating agent does not contain the aqueous polyurethane resin (A) and the compounding ratio of the water-soluble polymer (B) is 85%, the haze is 10% or less. Good gas barrier properties under high humidity could not be obtained.
In Comparative Example 12 in which the compounding ratio of the water-soluble polymer (B) was lower than in Comparative Example 11 and the compounding ratio of the inorganic layered mineral (C) was increased, the value of oxygen permeability was good, but the haze was 10 %, And the transparency of the gas barrier film was low.
In Comparative Example 13 using a coating agent in which the average particle diameter of the aqueous polyurethane resin (A) is larger than 100 nm and the compounding ratio of the inorganic layered mineral (C) is 5%, the haze is 10% or less. It was not possible to obtain good gas barrier properties under humidity.
Comparative example using a coating agent in which the average particle diameter of the aqueous polyurethane resin (A) is larger than 100 nm, the blending ratio of the inorganic layered mineral (C) is 25%, or the blending ratio of the water-soluble polymer (B) is 20% In 14-15, although the value of the oxygen permeability was good, the haze was 10% or more, and the transparency of the gas barrier film was low.

Claims (4)

An aqueous dispersion in which an aqueous polyurethane resin (A) containing an acid group-containing polyurethane resin and a polyamine compound is dispersed in an aqueous medium, a water-soluble polymer (B), and an inorganic layered mineral (C),
The average particle diameter of the aqueous polyurethane resin (A) is Ri der less 81 nm,
Coating said water-soluble polymer (B) is, the degree of saponification of 95% or more and a polymerization degree is characterized polyvinyl alcohol resin der Rukoto of 300 to 2000.   The ratio of the aqueous polyurethane resin (A) to the total solid content is 5 to 60% by mass, the ratio of the water-soluble polymer (B) is 25 to 80% by mass, and the ratio of the inorganic layered mineral (C) is 8 The coating agent of Claim 1 which is -20 mass%. A base film made of a plastic material,
A gas barrier layer formed of the coating agent according to claim 1 or 2, laminated on at least one surface of the base film.
A gas barrier film characterized by comprising:   The gas barrier film according to claim 3, having a haze of 10% or less.