JP7614560B2 - Gas barrier laminate film - Google Patents

Description

The present invention relates to a gas barrier laminate film that is transparent and has excellent gas barrier properties against water vapor, oxygen, etc., and is suitable for applications requiring high moisture resistance, such as confectionery, household goods, electronic components, and pharmaceuticals.

Conventionally, a gas barrier film has been known in which a thin metal film such as aluminum or a thin inorganic oxide film such as silicon oxide or aluminum oxide is laminated on the surface of a plastic film. In particular, a film laminated with a thin inorganic oxide film such as silicon oxide, aluminum oxide, or a mixture thereof is widely used for packaging food, daily necessities, electronic parts, medicines, etc., because it is transparent and allows the contents to be confirmed (see, for example, Patent Document 1).
These inorganic thin films are prone to pinholes and cracks during the thin film formation process, and furthermore, the inorganic thin film layer breaks down and cracks occur during processing, so that the expected sufficient gas barrier properties are not obtained.

Many gas barrier films have also been proposed by coating the surface of a plastic film with a resin composition. In particular, polyvinyl alcohol (hereinafter referred to as PVA) and ethylene-vinyl alcohol copolymer (hereinafter referred to as EVOH) have high oxygen barrier properties themselves and have been put to practical use as gas barrier coating agents, and are widely known as known technology (see, for example, Patent Document 2), but gas barrier properties have not been achieved.

Therefore, a technique is also widely known in which a vinyl alcohol resin, particularly a barrier resin such as PVA, is combined and laminated on an inorganic thin film layer in order to compensate for the lack of barrier properties of the vapor deposition film with a gas barrier resin. A technique is also widely known in which an inorganic layered compound is added to a resin such as PVA to further improve the oxygen barrier properties. Since the inorganic layered compound acts as a barrier against gas permeation, increasing the amount added also increases the barrier accordingly, so that the oxygen gas barrier properties tend to improve. However, as the amount added increases, the coating liquid becomes more viscous, making coating difficult. In addition, the coating film becomes more cloudy and the adhesion when laminated decreases. Although the above problems are avoided by reducing the amount of inorganic layered compound added, sufficient oxygen gas barrier properties are not obtained.

Patent No. 2929609 Japanese Patent Application Publication No. 7-80986

Molecular Materials Research Institute Hideki Kurita Toagosei Research Annual Report TREND 2003 No. 6, p.49.

The present invention was made against the background of such problems of the conventional technology. That is, the object of the present invention is to provide a gas barrier laminate film and a gas barrier packaging bag that exhibit high oxygen barrier properties not obtained with conventional vapor deposition films, while also achieving good appearance and adhesion of the film, and that can be used for packaging applications that require high oxygen gas barrier properties, such as confectionery, daily necessities, electronic components, and pharmaceuticals.

As a result of intensive investigations, the present inventors have confirmed that the oxygen gas barrier properties of coatings containing an inorganic layered compound according to the prior art are significantly different from the theoretical oxygen gas barrier properties shown in Non-Patent Document 1. It has been found that the reason for this is insufficient peeling and dispersion of the inorganic layered compound. The reason for insufficient dispersion is believed to be that the coating liquid is not subjected to sufficient shear. In response to this, it has been found that the peeling and dispersion of the inorganic layered compound are improved by applying high shear to the coating liquid with a rotation ratio of the reverse roll in the range of 1.1 to 2.0 in the reverse gravure coating method, thereby achieving high oxygen gas barrier properties of 55% or more relative to the theoretical oxygen gas barrier properties, while also achieving good appearance and adhesion of the film.
That is, the present invention comprises the following configuration.

1. A gas barrier laminate film comprising an inorganic thin film layer and a gas barrier resin composition layer laminated on at least one surface of a base film, the gas barrier resin composition layer containing a polyvinyl alcohol copolymer resin (component A) having a structural unit represented by the following chemical formula 1 in the molecule, a polyvinyl alcohol (co)polymer resin (component B) having a carbonyl group in the molecule, a hydrazine crosslinking agent (component C), and an inorganic layered compound (component D), and exhibiting a performance of 55% or more of the theoretical value (d2) of oxygen gas barrier property calculated by the following formula 1 from the oxygen gas barrier property (d1) of the polymer used alone and the thickness (W), length (L), and volume fraction (Vf) of the inorganic layered compound added.

（ただし、R_１およびR_２はそれぞれ独立して炭素数１～３の炭化水素基である。）

(wherein _R1 and _R2 are each independently a hydrocarbon group having 1 to 3 carbon atoms.)

d2=d1+d1・L・Vf/2W... Formula 1

2. The gas barrier laminate film according to 1., wherein the gas barrier resin composition layer satisfies the following conditions 1 to 3:
Condition 1: When the mass of component A contained in the barrier coating agent which forms the gas barrier resin composition layer is taken as WA and the mass of component B contained in the barrier coating agent is taken as WB, WA/WB is 20/80 to 70/30.
Condition 2: When the mass of the component B is WB and the mass of the component C is WC, WB/WC is 95/5 to 70/30.
Condition 3: When the mass of the component D contained in the barrier coating agent is WD, the ratio (WA+WB)/WD is 95/5 to 70/30.

3. The gas barrier laminate film according to 1. or 2., wherein the component A is a saponified copolymer of radical polymerizable monomers including a radical polymerizable monomer represented by the following chemical formula 2 and a vinyl ester monomer:

（Ｒ_１及びＲ_２はそれぞれ独立して炭素数１～３の炭化水素基であり、Ｒ_３及びＲ_４は、それぞれ独立して水素原子または－CO－Ｒ_５基（式中、Ｒ_５は、好ましくはメチル基、プロピル基、ブチル基、ヘキシル基またはオクチル基であり、かかるアルキル基は必要に応じて、ハロゲン基、水酸基、エステル基、カルボン酸基、スルホン酸基等の置換基を有していてもよい。）

( _R1 and _R2 are each independently a hydrocarbon group having 1 to 3 carbon atoms, and _R3 and _R4 are each independently a hydrogen atom or a -CO- _R5 group (wherein _R5 is preferably a methyl group, a propyl group, a butyl group, a hexyl group, or an octyl group, and such an alkyl group may have a substituent such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, or a sulfonic acid group, as necessary.)

4. A gas barrier laminate film according to any one of 1. to 3., in which component A is a polyvinyl alcohol copolymer resin represented by the following chemical formula 3:

（ただし、R_１およびR_２は前記と同じ定義、Ｘは共重合成分として用いられたラジカル重合性モノマーの分子構造に由来し、他の二つの構造単位に該当しない構造単位を表わす。）
ｌ、ｍ、ｎは、一分子あたりのそれぞれの構造単位の平均数を表し、ｌ＋ｍ＋ｎ＝３００～４０００、ｌ／（ｌ＋ｍ＋ｎ）＝０．００１～０．２、ｍ／（ｌ＋ｍ＋ｎ）＝０．８～０．９９、ｎ／（ｌ＋ｍ＋ｎ）＝０～０．１の関係を満足する。）

(wherein _R1 and _R2 are defined as above, and X is derived from the molecular structure of the radical polymerizable monomer used as a copolymerization component and represents a structural unit that does not fall under the other two structural units.)
l, m, and n represent the average number of each structural unit per molecule, and satisfy the relationships: l+m+n=300 to 4000, l/(l+m+n)=0.001 to 0.2, m/(l+m+n)=0.8 to 0.99, and n/(l+m+n)=0 to 0.1.

5. The gas barrier laminate film according to any one of 1. to 4., wherein the component B is a vinyl alcohol-based (co)polymer resin that satisfies the following condition 4 and/or condition 5:
Condition 4: A saponification product of a copolymer of radical polymerizable monomers including a vinyl ester monomer and a carbonyl group-containing radical polymerizable monomer.
Condition 5: An acetoacetylated product of a saponified (co)polymer of a radical polymerizable monomer containing a vinyl ester monomer.
6. The gas barrier laminate film according to any one of 1. to 5., wherein the component B is a polyvinyl alcohol-based (co)polymer resin containing, in the molecule, a structural unit represented by the following chemical formula 4 and/or a structural unit represented by the following chemical formula 5:

（ただし、Ｒ_６は水素またはメチル基である。）

(wherein _R6 is hydrogen or a methyl group.)

7. The gas barrier laminate film according to any one of claims 1 to 6, wherein component B is a polyvinyl alcohol-based (co)polymer resin represented by the following chemical formula 6:

（ただし、R_６は水素またはメチル基である。また、Ｙは共重合成分として用いられたラジカル重合性モノマーの分子構造に由来し、他の三つの構造単位に該当しない構造単位を表わす。
ｏ＋ｐ＋ｑ＋ｒは３００～４０００であって、（ｏ＋ｐ）／（ｏ＋ｐ＋ｑ＋ｒ）＝０．００１～０．２５、ｑ／（ｏ＋ｐ＋ｑ＋ｒ）＝０．７５～０．９９９、ｒ／（ｏ＋ｐ＋ｑ＋ｒ）＝０～０．２の関係を満足する。）

(wherein _R6 is hydrogen or a methyl group. Also, Y is derived from the molecular structure of the radically polymerizable monomer used as a copolymerization component and represents a structural unit that does not fall into the other three structural units.
o+p+q+r is 300 to 4000, and the relationships (o+p)/(o+p+q+r)=0.001 to 0.25, q/(o+p+q+r)=0.75 to 0.999, and r/(o+p+q+r)=0 to 0.2 are satisfied.)

8. The gas barrier laminate film according to any one of 1. to 7., wherein the inorganic thin film layer contains at least one type of inorganic oxide including silicon oxide and/or aluminum oxide.
9. A gas barrier packaging bag using the gas barrier laminate film according to any one of 1 to 8 above, the gas barrier packaging bag being arranged in the order of a base film layer, an inorganic thin film layer, and a gas barrier resin composition layer from the outside of the bag.

The present invention makes it possible to provide a gas barrier laminate film and a gas barrier packaging bag that have higher gas barrier properties against oxygen than conventional ones, and also have good appearance and adhesion.

The present invention is a gas barrier laminate film comprising an inorganic thin film layer and a gas barrier resin composition layer laminated on at least one surface of a base film, the gas barrier resin composition containing a vinyl alcohol copolymer resin (component A), a vinyl alcohol polymer resin having a carbonyl group in the molecule (component B), a hydrazine crosslinking agent (component C), an inorganic layered compound (component D) and an aqueous medium (component E). Each of the components is described in detail below.

1. Substrate Film The substrate film used in the present invention is made of an organic polymer, and is a film that has been melt-extruded, and then stretched in the longitudinal direction and/or the transverse direction, cooled, and heat-set as necessary. Examples of the organic polymer include polyamides such as nylon 4.6, nylon 6, nylon 6.6, and nylon 12; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate; polyolefins such as polyethylene, polypropylene, and polybutene; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, wholly aromatic polyamide, polyamideimide, polyimide, polyetherimide, polysulfone, polystyrene, and polylactic acid. Among these, polyester or polyamide is preferred, and polyester is more preferred.
The substrate film in the present invention may be a laminated film. When the substrate film is a laminated film, the type of each layer, the number of layers, the lamination method, etc. are not particularly limited, and can be arbitrarily selected from known methods depending on the purpose.
The substrate film may be copolymerized or blended with a small amount of other organic polymers. The substrate film may be produced by any of the existing methods, such as coextrusion and casting.

Among these, specific examples of preferred polyamides include polycaproamide (nylon 6), poly-ε-aminoheptanoic acid (nylon 7), poly-ε-aminononanoic acid (nylon 9), polyundecaneamide (nylon 11), polylaurinlactam (nylon 12), polyethylenediamineadipamide (nylon 2.6), polytetramethyleneadipamide (nylon 4.6), polyhexamethyleneadipamide (nylon 6.6), polyhexamethylenesebacamide (nylon 6.10), polyhexamethylenedodecamamide (nylon 6.12), polyoctamethylenedodecamamide (nylon 6.12), polyoctamethyleneadipamide (nylon 8.6), polydecamethyleneadipamide (nylon 10.6), polydecamethylenesebacamide (nylon 11.1), polytetramethyleneadipamide (nylon 11.1), polyhexamethylenesebac ... Examples of the polyamide include poly(Nylon 10-10), poly(dodecamethylene dodecamide) (Nylon 12-12), and metaxylenediamine-6 nylon (MXD6), and may be copolymers having these as main components, and examples thereof include caprolactam/laurinlactam copolymer, caprolactam/hexamethylenediammonium adipate copolymer, laurinlactam/hexamethylenediammonium adipate copolymer, hexamethylenediammonium adipate/hexamethylenediammonium sebacate copolymer, ethylenediammonium adipate/hexamethylenediammonium adipate copolymer, and caprolactam/hexamethylenediammonium adipate/hexamethylenediammonium sebacate copolymer. It is also effective to blend plasticizers such as aromatic sulfonamides, p-hydroxybenzoic acid, and esters, elastomer components with low elasticity, and lactams as film flexibility improving components with these polyamides. Of these, polycaproamide (nylon 6) is preferred.

Specific examples of preferred polyesters include polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, among which polyethylene terephthalate is preferred. Copolymers containing these as the main component may also be used, and when a polyester copolymer is used, the main component of the dicarboxylic acid component may be an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, phthalic acid, or 2,6-naphthalenedicarboxylic acid, a polyfunctional carboxylic acid such as trimellitic acid and pyromellitic acid, or an aliphatic dicarboxylic acid such as adipic acid or sebacic acid.
In addition, although ethylene glycol or 1,4-butanediol is used as the main component of the glycol component, other aliphatic glycols such as diethylene glycol, propylene glycol, and neopentyl glycol, aromatic glycols such as p-xylylene glycol, alicyclic glycols such as 1,4-cyclohexanedimethanol, and polyethylene glycols having an average molecular weight of 150 to 20,000 can also be used.
The preferred ratio of the copolymerization component in the polyester is 2% or less. If the copolymerization component exceeds 20%, the film strength, transparency, heat resistance, etc. may be deteriorated.

Furthermore, the above organic polymer may contain known additives, such as ultraviolet absorbers, antistatic agents, plasticizers, lubricants, colorants, etc., and the transparency of the base film is not particularly limited, but when used as a transparent packaging material laminate, it is desirable for the film to have a transmittance of 50% or more.
The base film in the present invention may be subjected to a surface treatment such as corona discharge treatment, glow discharge treatment, flame treatment, surface roughening treatment, etc., prior to laminating the thin film layer, as long as the object of the present invention is not impaired. The base film may also be subjected to a known anchor coat treatment, printing, decoration, etc. The thickness of the plastic film in the present invention is preferably in the range of 1 to 500 μm, more preferably in the range of 2 to 300 μm, and most preferably in the range of 3 to 100 μm.
From the viewpoint of imparting mechanical strength, the base film is preferably a stretched film stretched in at least one of the longitudinal and transverse directions, and is preferably a biaxially stretched film stretched in two directions, the longitudinal and transverse directions. The stretching method for the biaxially stretched film can be any method such as simultaneous biaxial stretching or sequential biaxial stretching.

2. Inorganic thin film layer The inorganic thin film layer in the present invention is preferably an inorganic oxide thin film. For example, there is no particular limitation as long as it can be made into a thin film, such as silicon oxide, aluminum oxide, magnesium oxide, etc., but the thin film layer preferably contains at least one type of inorganic oxide including silicon oxide and/or aluminum oxide.
The thin film layer containing at least one type of inorganic oxide including silicon oxide and/or aluminum oxide is a thin film formed from an inorganic oxide by a known method.
Silicon oxide here refers to a mixture of various silicon oxides such as Si, SiO, and _SiO2 , and aluminum oxide refers to a mixture of various aluminum oxides such as AlO and _Al2O3 , and the amount of oxygen bonded in each _oxide varies depending on the production conditions.

When the specific gravity of a binary inorganic oxide thin film consisting of silicon oxide and aluminum oxide is expressed by the relationship between the specific gravity of the thin film and the aluminum oxide content (mass %) in the thin film, D = 0.01A + b (D: specific gravity of the thin film, A: aluminum oxide content in the thin film), the b value is preferably 1.2 to 2.2, and more preferably 1.7 to 2.1.

Furthermore, when the relationship between the specific gravity value of a binary inorganic oxide thin film and the content (mass %) of aluminum oxide in the inorganic oxide thin film is expressed as D = 0.01A + b (D: specific gravity of the thin film, A: mass % of aluminum oxide in the thin film), when the b value is in the range smaller than 1.6, the structure of the silicon oxide/aluminum oxide thin film becomes coarse, and when the b value is in the range larger than 2.2, the silicon oxide/aluminum oxide thin film tends to become hard.

The content of aluminum oxide in the binary inorganic oxide thin film is preferably 20 to 99% by weight, and more preferably 20 to 75% by weight.
If the content of aluminum oxide in the binary inorganic oxide thin film is less than 20 mass %, the gas barrier properties are not necessarily sufficient, whereas if the amount of aluminum oxide in the binary inorganic oxide thin film exceeds 99 mass %, the flexibility of the vapor-deposited film decreases, making the gas barrier laminate relatively weak against bending and dimensional changes, and problems may arise in which the effect of using the two in combination is reduced.

In the present invention, the thickness of the inorganic thin film layer is usually 1 to 50 nm, preferably 5 to 30 nm. If the thickness is less than 1 nm, it is difficult to obtain satisfactory gas barrier properties, and even if the thickness is made excessively thicker than 50 nm, the corresponding improvement in gas barrier properties cannot be obtained, and it is actually disadvantageous in terms of bending resistance and manufacturing costs.

A typical method for forming an inorganic thin film layer will be explained by forming an inorganic oxide-based thin film containing silicon oxide and/or aluminum oxide. As a thin film formation method by vapor deposition, physical vapor deposition methods such as vacuum heating vapor deposition, sputtering, and ion plating, or CVD (chemical vapor deposition) are appropriately used. For example, when the vacuum vapor deposition method is adopted, Al or a mixture of SiO ₂ and Al ₂ O ₃ , or a mixture of SiO ₂ and Al, is used as a vapor deposition raw material. For heating, resistance heating, high-frequency induction heating, electron beam heating, etc. can be adopted, and it is also possible to introduce oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor, etc. as a reactive gas, or to adopt reactive vapor deposition using means such as ozone addition and ion assist. Furthermore, the film formation conditions can be arbitrarily changed, such as applying a bias to the plastic film, or heating or cooling the plastic film. The above-mentioned vapor deposition materials, reactive gases, substrate bias, heating/cooling, etc. can be changed in the same way when the sputtering method or CVD method is adopted.

3. Gas Barrier Resin Composition Layer The gas barrier resin composition layer in the present invention preferably contains a vinyl alcohol copolymer resin (component A), a vinyl alcohol polymer resin having a carbonyl group in the molecule (component B), a hydrazine crosslinking agent (component C), and an inorganic layered compound (component D). The gas barrier coating agent for forming the gas barrier resin composition layer will be described later.

<Gas barrier resin, crosslinking agent>
Conventionally, vinyl alcohol resins such as PVA have been known to have high oxygen gas barrier properties and have been widely used as oxygen barrier resins. It has also been found that the addition of an inorganic layered compound can provide further barrier properties. However, the actual oxygen gas barrier properties of these resins deviate from the theoretical values of barrier properties when inorganic substances are added, as shown in Non-Patent Document 1.
The phenomenon of gas molecules permeating a polymer film is explained by the solution-diffusion theory, where the permeability coefficient (P) is expressed as the product of the solubility coefficient (S) and the diffusion coefficient (D), that is, P = D S. Here, the diffusion coefficient (D) is considered to be determined by the gas path length.
Since inorganic layered compounds act as a barrier to gas permeation, if they are sufficiently dispersed, a maze effect will occur in which gas will bypass the inorganic layered compounds and permeate, resulting in a gas permeation path (gas path length) that is longer than the thickness of the resin, resulting in high oxygen gas barrier properties. However, in conventional products, the inorganic layered compounds are not sufficiently dispersed, so it is thought that they do not exhibit ideal oxygen gas barrier properties.
Thus, the inventors have found that by applying high shear to the coating solution during coating, a coating film in which the inorganic layered compound is sufficiently dispersed is formed, and high oxygen gas barrier properties of 55% or more are achieved relative to the theoretical value of oxygen gas barrier properties when inorganic substances are added as shown in Non-Patent Document 1.

The theoretical value of the oxygen gas barrier property referred to here was calculated by the following formula 1 shown in Non-Patent Document 1. d1: gas path length of the polymer alone, d2: gas path length of the polymer-inorganic layered compound hybrid, W: thickness of the inorganic layered compound, L: length of the inorganic layered compound, Vf: volume fraction of the inorganic layered compound.
(Oxygen gas barrier property theoretical value calculation formula)
d2=d1+d1・L・Vf/2W... Formula 1

In addition, oxygen gas barrier property means oxygen transmission rate (OTR). In this invention, the OTR evaluation of the film produced was carried out under the conditions of 23°C and 65% RH.

4. Gas Barrier Coating Agent The gas barrier coating agent for forming the gas barrier resin composition layer of the present invention contains a modified vinyl alcohol (co)polymer resin (Component A, Component B), a hydrazine crosslinking agent (Component C), an inorganic layered compound (Component D) and a solvent (sometimes referred to as Component E).

<Modified vinyl alcohol (co)polymer resin>
The vinyl alcohol copolymer resin (component A) contained in the gas barrier coating agent of the present invention and having in its molecule a structural unit represented by the following chemical formula 1 will now be described.

（R_１およびR_２はそれぞれ独立して炭素数１～３の炭化水素基である。）

( _R1 and _R2 are each independently a hydrocarbon group having 1 to 3 carbon atoms.)

Details of the materials, synthesis methods, saponification methods, etc. for synthesizing Component A are disclosed in JP 2006-176589 A. The polyvinyl alcohol copolymer resin obtained using the materials, synthesis methods, saponification methods, etc. described as particularly suitable in the same publication can also be suitably used as Component A of the gas barrier coating agent of the present invention.
Here, as a method for introducing the structural unit represented by the above chemical formula 1 into the molecule of component A, a method of copolymerizing a vinyl ester monomer with a radical polymerizable monomer represented by the following chemical formula 2 can be used, and the obtained copolymer is saponified to form a polyvinyl alcohol copolymer resin.

In the above chemical formula 2, _R1 and _R2 are each independently a hydrocarbon group having 1 to 3 carbon atoms, and _R3 and _R4 are each independently a hydrogen atom or a -CO- _R5 group (wherein _R5 is preferably a methyl group, a propyl group, a butyl group, a hexyl group, or an octyl group, and such an alkyl group may have a substituent such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, or a sulfonic acid group, as necessary.

Examples of the radical polymerizable monomer represented by the chemical formula 2 include 1,4-dihydroxy-2-butene, 1,4-diacyloxy-2-butene, 1-hydroxy-4-acyloxy-2-butene, 1,4-diacyloxy-1-methyl-2-butene, 1,5-diacyloxy-2-pentene, 1,6-diacyloxy-2-hexene, and 1,6-diacyloxy-3-hexene. Among these, 1,4-diacyloxy-2-butene in which R1 and R2 are methylene groups, R3 and R4 are -CO-R5, and R5 is an alkyl group is preferred in terms of excellent copolymerization reactivity and industrial handling, and among these, 1,4-diacetoxy-2-butene in which R3 is a methyl group is particularly preferred.
The polyvinyl alcohol copolymer resin obtained by the above copolymerization components and production method can be simply represented by the following chemical formula 3.

Here, _R1 and _R2 are defined as in formula 1. X is derived from the molecular structure of the radical polymerizable monomer used as a copolymerization component and represents a structural unit that does not fall under the other two structural units, specifically, the site where at least one of _R3 or _R4 is a -CO- _R5 group even after the radical polymerizable monomer represented by formula 2 is copolymerized and saponified, the site that is not saponified after the vinyl ester monomer is copolymerized, and the site where other radical polymerizable monomers used as necessary are copolymerized. Note that formula 3 simply shows the form of a block copolymer of three structural units, but there is no particular restriction on the arrangement of the three structural units, and it also includes a random copolymer.
Each of l, m, and n represents the average number of each structural unit per molecule, and satisfies the relationships: l+m+n=300 to 4000, l/(l+m+n)=0.001 to 0.2, m/(l+m+n)=0.8 to 0.99, and n/(l+m+n)=0 to 0.1.
Examples of commercially available products of such component A include OKS-1109 and OKS-8049 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

The gas barrier coating agent for forming the gas barrier resin composition layer of the present invention contains a vinyl alcohol-based (co)polymer resin having a carbonyl group in the molecule (hereinafter, sometimes referred to as component B). The term "(co)polymerization" includes both homopolymerization using one type of radically polymerizable monomer and copolymerization using two or more types of radically polymerizable monomer, and the term "(co)polymer resin" includes both homopolymer resin obtained by homopolymerizing one type of radically polymerizable monomer and copolymer resin obtained by copolymerizing two or more types of radically polymerizable monomer.
First, as a method for introducing a carbonyl group into the molecule of component B, there can be used (1) a method for copolymerizing a vinyl ester monomer with a carbonyl group-containing monomer having a carbonyl group in the molecule and the carbonyl group is not removed from the molecule of the polyvinyl alcohol copolymer by saponification, and (2) a method for polymerizing a polymerization component containing a vinyl ester monomer, generating a hydroxyl group by saponification, and further acetylating the hydroxyl group, and the like.

Specifically, the vinyl ester monomer (1) may be any of those listed above. Examples of the carbonyl group-containing monomer include vinyl ketones and diacetone (meth)acrylamide, with diacetone (meth)acrylamide being preferred.
As a method for copolymerizing the vinyl ester monomer, the carbonyl group-containing monomer, and, if necessary, other radical polymerizable monomers within a range that does not impair the effects of the present invention, known methods such as ordinary solution polymerization, bulk polymerization, emulsion polymerization, etc. can be used without particular limitation. According to this method, for example, when diacetone (meth)acrylamide is used as a copolymerization component, a structural unit represented by the following chemical formula 4 can be introduced as component B into the molecule of a polyvinyl alcohol copolymer resin.

（ただし、Ｒ_６は水素またはメチル基である）

(wherein _R6 is hydrogen or a methyl group).

Furthermore, a method can also be used in which a polyvinyl alcohol (co)polymer resin is first synthesized, and then a carbonyl group is introduced by acetoacetylation of the hydroxyl group in the molecule.
Specifically, the polyvinyl alcohol-based (co)polymer resin can be produced by reacting diketene directly with gaseous or liquid diketene, by previously adsorbing and occluding an organic acid such as acetic acid, and then reacting the same with gaseous or liquid diketene in an inert gas atmosphere, or by spraying a mixture of an organic acid and diketene and reacting them (reaction generation step), followed by washing and removing unreacted diketene with an alcohol having 1 to 3 carbon atoms (washing step), and then drying under predetermined conditions (drying step).
According to this method, a structural unit represented by the following chemical formula 5 can be introduced as component B into the molecule of the polyvinyl alcohol-based (co)polymer resin.

The polyvinyl alcohol polymer resin obtained from the above copolymer components and manufacturing method can be simply represented by the following chemical formula 6.

_R6 is hydrogen or a methyl group. Y is derived from the molecular structure of the radical polymerizable monomer used as a copolymerization component and represents a structural unit that does not fall under the other three structural units, specifically, the portion that is not saponified after the vinyl ester monomer is copolymerized, and the portion that is copolymerized with other radical polymerizable monomers used as necessary. Although chemical formula 6 simply shows the form of a block copolymer of four structural units, there is no particular restriction on the arrangement of the four structural units, and it also includes random copolymers.
o+p+q+r is 300 to 4000, and the relationships (o+p)/(o+p+q+r) = 0.001 to 0.25, q/(o+p+q+r) = 0.75 to 0.999, and r/(o+p+q+r) = 0 to 0.2 are satisfied.

<Hydrazine-based crosslinking agent>
The hydrazine-based crosslinking agent (component C) contained in the gas barrier coating agent of the present invention is a compound having two or more hydrazine residues in the molecule, and preferably includes alkylene dihydrazines represented by the following chemical formula 7, or dihydrazide compounds of saturated aliphatic dibasic acids or unsaturated dibasic acids.

式中、Ｚは１～８個の炭素を有するアルキレン基、あるいは１～１０個の炭素を有する飽和または不飽和二塩基酸の残基を表す。

In the formula, Z represents an alkylene group having 1 to 8 carbons, or the residue of a saturated or unsaturated dibasic acid having 1 to 10 carbons.

Specific examples of alkylene dihydrazines include methylene dihydrazine, ethylene dihydrazine, propylene dihydrazine, butylene dihydrazine, etc. Examples of dihydrazide compounds of saturated aliphatic dibasic acids include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, and sebacic acid dihydrazide, and examples of dihydrazide compounds of unsaturated dibasic acids include phthalic acid dihydrazide, fumaric acid dihydrazide, and itaconic acid dihydrazide.

<Inorganic Layered Compound>
The inorganic layered compound (component D) contained in the gas barrier coating agent of the present invention has cationic metal atoms or inorganic atomic groups between layers, and utilizes the property that the metal atoms or inorganic atomic groups are ionized and eluted into the solvent, either by the solvent described below or by a separate solvent used during the swelling/cleavage treatment, thereby cleaving.
Component D has a structure in which many thin-film layers with a thickness of about 0.5 to 3 nm and a width of about 100 nm to several μm are laminated, and even a single layer has high gas barrier ability. Therefore, even if the content of component D in the gas barrier coating agent is the same, the gas barrier properties of the coating film formed in a system with a more advanced degree of cleavage are higher. Furthermore, when the coating film is subjected to stress due to elongation or peeling, a system with a more advanced degree of cleavage can suppress a decrease in fracture strength caused by interlayer peeling at uncleaved parts of the inorganic layered compound. In this way, component D is extremely suitable as a material that achieves the effects of the present invention, since it can be easily cleaved to a single layer by ionizing cationic metal atoms, etc., present between the layers with water or the like and dissolving them in a solvent. As these inorganic layered compounds, clay minerals having swelling properties are preferable, and specifically, they are classified into a type having a two-layer structure in which an octahedral layer with aluminum, magnesium, etc. as a central metal is placed on top of a tetrahedral layer of silica, and a type having a three-layer structure in which a tetrahedral layer of silica sandwiches an octahedral layer with aluminum, magnesium, etc. as a central metal on both sides. Examples of the former include the kaolinite group and the antigorite group belonging to the jamonite group, and examples of the latter include the smectite group, vermiculite group, mica group, etc. depending on the number of interlayer cations.
Specifically, kaolinite, nacrite, dickite, halloysite, hydrated halloysite, antigorite, chrysotile, pyrophyllite, montmorillonite, beidellite, saponite, hectorite, sauconite, stevensite, tetrasilylic mica, sodium taeniolite, muscovite, margarite, talc, vermiculite, phlogopite, xanthophyllite, chlorite, etc. may be mentioned, and these may be natural products or synthetic products. In addition, scaly silica, etc. may also be used. These may be used alone or in combination of two or more kinds.
Among these, montmorillonite is preferred because it has excellent gas barrier properties and coating suitability when used as a coating agent.

<Solvent>
The solvent contained in the gas barrier coating agent of the present invention may be either an aqueous or non-aqueous solvent capable of dissolving the polyvinyl alcohol-based (co)polymer resin. The aqueous solvent may be mainly composed of water, and may be used in combination with a water-soluble organic solvent as required. Examples of the water-soluble organic solvent that may be used in combination include lower alcohols such as methanol, ethanol, and isopropanol, polyhydric alcohols such as ethylene glycol and propylene glycol, and derivatives thereof, ethyl acetate, and methyl ethyl ketone. The use of such organic solvents can improve the solubility of component A and component B, and can adjust the drying property of the gas barrier coating agent and its wettability to the substrate film.
If necessary, a non-aqueous solvent can be prepared by using an organic solvent that dissolves components A and B. In this case, a dispersion treatment is separately performed in which cationic metal atoms or the like present between the layers of component D are ionized and dissolved in water, and the mixture is swelled and cleaved, and then the water is replaced with another organic solvent, thereby realizing a completely non-aqueous solvent system as a gas barrier coating agent. In a non-aqueous solvent system, even organic solvents with low solubility in water can be used, so that the drying property of the gas barrier coating agent and the wettability to the substrate film can be adjusted more widely, and there is also the possibility of increasing the number of additives and substrate films that can be applied.
Examples of organic solvents that can be used in the non-aqueous solvent system include the organic solvents listed above, as well as slower drying acetate ester solvents such as propyl acetate and butyl acetate.

<Additives>
To the gas barrier coating agent of the present invention, leveling agents, antifoaming agents, antiblocking agents such as wax and silica, release agents such as metal soaps and amides, ultraviolet absorbers, antistatic agents, etc. may be added as necessary.

<Content ratio>
Of these materials used in the gas barrier coating agent of the present invention, from the viewpoint of having excellent gas barrier properties and being able to maintain high film cohesive strength, it is preferable that the content ratio of component A to component B is WA/WB=20/80 to 70/30, where WA is the mass of component A contained in the barrier coating agent and WB is the mass of component B contained in the barrier coating agent.
Here, if the WA content is higher than the range of WA/WB = 20/80 to 70/30, the concentration of carbonyl groups crosslinked with component C will be lower, which may reduce the cohesive strength of the coating obtained by coating with the gas barrier coating agent and the adhesion to the plastic film substrate. Also, when used in a laminate composite film, sufficient laminate strength may not be obtained. On the other hand, if the WA content is low, it may not be possible to obtain good gas barrier properties, especially good water vapor barrier properties, in the thin film.

The content ratio of component C is preferably WB/WC=95/5 to 70/30.
Here, if the WB content is higher than the range of WB/WC = 95/5 to 70/30, the cohesive strength of the coating obtained by coating the gas barrier coating agent and the adhesion to the plastic film substrate may decrease. In addition, when used in a laminate composite film, sufficient laminate strength may not be obtained. On the other hand, a low WB content means that the content of component C is greatly excessive, and it may not be possible to obtain good gas barrier properties, especially good water vapor barrier properties, in the thin film.
The content ratio of component D is expressed as the mass of component D contained in the barrier coating agent W
When D is used, it is preferable that (WA+WB)/WD=95/5 to 70/30.
If the (WA+WB) content ratio is higher than the range of (WA+WB)/WD = 95/5 to 70/30, it may not be possible to obtain good gas barrier properties in the thin film.On the other hand, if the (WA+WB) content ratio is low, the cohesive strength of the film obtained by applying the gas barrier coating agent decreases, and the adhesion to the plastic film substrate decreases, so that sufficient laminate strength may not be obtained when used in a laminate composite film.

<Method of stirring coating liquid>
A general propeller type stirrer can be used as a method for stirring the coating liquid. Specifically, the above-mentioned solvent and each material of the gas barrier resin composition are placed in a liquid preparation tank, and the materials are thoroughly stirred using a propeller type stirrer to dissolve and disperse each material of the gas barrier resin composition in the solvent.

(2) Lamination method Methods for laminating a gas barrier resin composition layer on an inorganic thin film layer include a method of coating a coating liquid prepared by dissolving/dispersing each material of the gas barrier resin composition in a solvent onto the inorganic thin film layer of a film having an inorganic thin film layer, a method of melting the gas barrier resin composition and extruding it onto the inorganic thin film layer of a film having an inorganic thin film layer to laminate it, and a method of separately preparing a film of the gas barrier resin composition and attaching it to the inorganic thin film layer of a film having an inorganic thin film layer with an adhesive, etc. Among these, the coating method is preferred from the standpoint of simplicity, productivity, etc.

Hereinafter, as a preferred lamination method, a method in which a coating liquid prepared by dissolving or dispersing each material of the gas barrier resin composition in a solvent is applied onto the inorganic thin film layer of a film having an inorganic thin film layer will be described.
As the solvent for the gas barrier resin composition, either an aqueous or non-aqueous solvent capable of dissolving the vinyl alcohol polymer resin can be used, but it is preferable to use water or a mixed solvent of water and isopropyl alcohol. The coating method is not particularly limited as long as it is a coating method that can apply high shear to the coating liquid during coating, but coating with a reverse gravure coater with a gear ratio of the reverse roll in the range of 1.1 to 2.0 is preferable. If the gear ratio is less than 1.1, the supply of the coating liquid becomes unstable, coating unevenness occurs, and the coating film becomes unstable, so that high barrier properties cannot be expressed. In addition, if the gear ratio exceeds 2.0, the inorganic vapor deposition layer of the vapor deposition film to be coated is scratched, the barrier properties of the vapor deposition layer are impaired, and high barrier properties cannot be expressed.

(3) Thickness of the Gas Barrier Resin Composition Layer The thickness (μm) of the gas barrier resin composition layer is preferably 0.01 to 0.70 μm, more preferably 0.05 to 0.50 μm, and particularly preferably 0.08 to 0.50 μm. If it is less than 0.01 μm, the gas barrier properties will decrease, and if it exceeds 0.70 μm, there is a risk that insufficient drying will occur during coating, causing problems such as blocking with the roll used to form the layer, or that the gas barrier resin composition layer will become brittle, resulting in a decrease in laminate strength.

(4) Drying Conditions for the Gas Barrier Resin Composition Layer The drying temperature after coating with the coating liquid of the gas barrier resin composition is preferably 100 to 200° C., more preferably 130 to 200° C., and even more preferably 150 to 200° C. If the temperature is less than 100° C., the coating layer will not dry sufficiently, causing problems such as blocking when the layer is used as a roll. In addition, the gas barrier resin composition layer will become brittle, decreasing the laminate strength.
On the other hand, if the temperature exceeds 200° C., the film will be too hot, making the base film brittle and shrinking, resulting in poor processability.

(5) Stacking order of gas barrier laminate film In order to realize moisture proofing of the gas barrier laminate film, it is necessary to arrange the layers in the order of base film layer, inorganic thin film layer, and gas barrier resin composition layer from the high humidity side. By arranging the inorganic thin film layer on the high humidity side of the gas barrier resin composition layer, which is highly humidity dependent, it is possible to prevent the gas barrier resin composition layer from being exposed to high humidity and thus preventing a decrease in the barrier property.

The gas barrier property was measured in the following manner.
(6) Water vapor permeability The gas barrier laminate film having the inorganic thin film layer and the gas barrier resin composition layer laminated thereon was placed in a water vapor permeability measuring device (PERMATRAN-W3/33MG manufactured by MOCON) so that the surface of the substrate film of the gas barrier laminate film was the side through which the humidity-control gas of the measuring device flowed, and the water vapor permeability was measured in an atmosphere of a temperature of 40°C and a humidity of 90% RH according to JIS K7126 method B. The humidity control of the gas barrier laminate film was performed for 4 hours in the direction in which water vapor permeated from the film substrate side to the gas barrier resin composition layer side.

The gas barrier laminate film of the present invention can be used for various applications including food packaging, and can be laminated with other materials such as a heat seal layer, a printed layer, other resin films, an adhesive layer for bonding these layers, etc. When laminating, known means can be used, such as a method of directly melt extrusion laminating on the gas barrier laminate film of the present invention, a coating method, or a method of laminating films together directly or via an adhesive.
In addition, when high gas barrier properties are required, two or more gas barrier laminate films of the present invention may be laminated. In addition, an inorganic deposition layer may be provided on a gas barrier resin composition layer, and a gas barrier resin composition layer may be provided on the inorganic deposition layer, and the like, so that they may be laminated alternately. Furthermore, an inorganic deposition layer, a gas barrier resin composition layer, and an anchor layer, etc., if necessary, may be provided on both sides of a substrate film.
For example, when used as a lid material or packaging bag for confectionery, daily necessities, electronic parts, medicines, etc. that require moisture resistance, it is preferable to provide a heat seal layer such as polyethylene or polypropylene on the gas barrier resin composition layer. In addition, another resin film may be laminated between the gas barrier resin layer and the heat seal layer. As the other resin film, the resin films listed as the substrate film can be used. When laminating these, they can be laminated via an adhesive.
In particular, a preferred form of use is to place a moisture-absorbing material such as a desiccant inside the container or packaging bag.

The gas barrier laminate film of the present invention is particularly effective for use in packaging bags that protect the contents from external moisture, in the order of the outside where humidity is high, that is, a base film, an inorganic thin film layer, and a gas barrier resin composition layer.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass." The methods for evaluating physical properties in the following examples and comparative examples are as follows.

(1) Evaluation of Actual Value with Respect to Theoretical Value of Oxygen Gas Barrier Property Based on the gas barrier resin composition layer used and the amount and size of the inorganic layered compound added, the theoretical value of oxygen gas barrier property was calculated using the following formula 1.
d2=d1+d1・L・Vf/2W... Formula 1

For example, in the case of Example 1, the OTR of the polymer alone is 4.94 mL/ ^m2 ·d·MPa, so this is the gas path length of the polymer alone, d1=4.94, the average thickness of the added inorganic layered compound is 1.2 nm, so W=1.2, the average particle size is 560 nm, so L=560, and the volume fraction of the inorganic layered compound to the polymer is 0.071, so Vf=0.071. By inserting the values into the above formula 1, d1 is calculated as d2=86.7. The theoretical value of the gas path length when the inorganic layered compound is added is 86.7, which is 17.55 times longer than the gas path length of the polymer alone. Since the gas permeation path length is 17.55 times longer, the OTR is 1/17.55, so the value obtained by dividing the OTR of the polymer alone, 4.94 mL/ ^m2 ·d·MPa, by 17.55, is the theoretical value of the OTR. Here, the theoretical OTR value was calculated to be 0.3 mL/ ^m2 ·d·MPa.
Next, the actual value of the oxygen gas barrier was measured by the method described below. The measured value was 0.40 mL/ ^m2 ·d·MPa. Based on these values, the actual value with respect to the theoretical value of the oxygen gas barrier (theoretical gas barrier value/actual gas barrier value×100) was calculated to be 75%. Examples 2 to 7 and Comparative Examples 1 to 6 and 8 to 13 were also evaluated by the same method. Note that, since no inorganic layered compound was added to Comparative Example 7, the theoretical value was not calculated. Note that the actual value (%) with respect to the theoretical value of the oxygen gas barrier described above was calculated as an integer value (%) by rounding off the value to one decimal place.

(2) Water Vapor Permeability of Gas Barrier Laminate Film The gas barrier laminate films obtained in the Examples and Comparative Examples were placed in a water vapor permeability measuring device (PERMATRAN-W3/33, manufactured by MG MOCON) so that the surface of the substrate film of the gas barrier laminate film was on the side where the humidity-conditioning gas of the measuring device flowed, and the water vapor permeability was measured in an atmosphere of a temperature of 40° C. and a humidity of 90% RH in accordance with JIS K7126 Method B. The humidity conditioning of the gas barrier laminate film was performed for 4 hours in the direction in which water vapor permeated from the film substrate layer side to the gas barrier resin composition layer side.

(3) Oxygen transmission rate (OTR) of gas barrier laminate film
The gas barrier laminate films obtained in the Examples and Comparative Examples were placed in an oxygen permeability measuring device (OX-TRAN 2/20, manufactured by MOCON) so that the surface of the substrate film of the gas barrier laminate film was the oxygen gas flowing side of the measuring device, and the oxygen permeability was measured in an atmosphere of a temperature of 23° C. and a humidity of 65% RH in accordance with JIS K7126-2. The humidity of the gas barrier laminate film was adjusted to 65% RH on both the gas barrier coating layer side and the film substrate side for 4 hours.

(Preparation of Coating Solution for Forming Gas Barrier Resin Composition Layer)
The preparation of a coating solution for forming a gas barrier resin composition layer used in the examples and comparative examples will be described below.

<Mixed solution (hereinafter abbreviated as mixed solution) of a vinyl alcohol copolymer resin having the structural unit of the above formula 1 in the molecule (component A, hereinafter abbreviated as component A), a vinyl alcohol polymer resin having a carbonyl group in the molecule (component B, hereinafter abbreviated as component B), and an inorganic layered compound (hereinafter abbreviated as component D)>
Component A, Component B, and Component D were mixed into an aqueous mixed solvent mainly composed of purified water and IPA (isopropanol) to prepare a solids concentration of 4.2% by mass.

The mixed solutions used in the examples are described below.
Component A represents a polyvinyl alcohol-based copolymer resin having a structural unit represented by formula 1 in the molecule, component B represents a polyvinyl alcohol-based (co)polymer resin represented by formula 6, and component D represents montmorillonite.
<Mixed solution 1>
The solid content of the mixed solution was adjusted to a composition ratio of component A/component B/component D = 34/51/15, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 2>
The solid content of the mixed solution was mixed in a ratio of component A/component B/component D = 17/68/15, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 3>
The solid content of the mixed solution was mixed in a ratio of component A/component B/component D = 25.5/59.5/15, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 4>
The solid content of the mixed solution was mixed in a ratio of component A/component B/component D = 42.5/42.5/15, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 5>
The solid content of the mixed solution was mixed in a ratio of component A/component B/component D = 59.5/25.5/15, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 6>
The solid content of the mixed solution was adjusted to a composition ratio of component A/component B/component D = 0/85/15, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 7>
The solid content of the mixed solution was adjusted to a composition ratio of component A/component B/component D = 40/60/0, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 8>
The solid content of the mixed solution was adjusted to a composition ratio of component A/component B/component D = 38/57/5, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 9>
The solid content of the mixed solution was adjusted to a composition ratio of component A/component B/component D = 28/42/30, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 10>
The solid content of the mixed solution was adjusted to a composition ratio of component A/component B/component D = 24/36/40, and the solid content concentration was adjusted to 6.5 mass %.
<Mixed solution 11>
The solid content of the mixed solution was mixed in a ratio of component A/component B/component D = 68/17/15, and the solid content concentration was adjusted to 6.5 mass %.

<Crosslinking Agent>
Hydrazine-based crosslinking agent (component C) (Sakata Inx Corporation, product name Eco Stage Crosslinking Agent S, solid content approximately 5%)

<Mixed Solvent A>
Purified water and IPA were mixed in a 1:1 ratio.

<Preparation of Coating Fluids for Forming Gas Barrier Resin Composition Layers in Examples 1 to 3 and Comparative Examples 1 to 5>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 1 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain coating solutions for forming gas barrier resin composition layers of Examples 1 to 3 and Comparative Examples 1 to 3, each having a solid content of about 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Example 4>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 2 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Example 4 with a solid content of approximately 4.2%.

<Preparation of Coating Solution for Forming Gas Barrier Resin Composition Layer of Example 5>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 3 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Example 5 with a solid content of approximately 4.2%.

<Preparation of Coating Solution for Forming Gas Barrier Resin Composition Layer of Example 6>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 4 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Example 6 with a solid content of approximately 4.2%.

<Preparation of Coating Solution for Forming Gas Barrier Resin Composition Layer of Example 7>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 5 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Example 7 with a solids content of approximately 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Comparative Example 6>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 6 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Comparative Example 6 with a solid content of approximately 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Comparative Example 7>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 7 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Comparative Example 7 with a solid content of approximately 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Comparative Example 8>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 8 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Comparative Example 8 with a solid content of approximately 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Comparative Example 9>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 9 was added, and the mixture was thoroughly stirred and mixed. Then, 4.0 parts by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Comparative Example 9 with a solid content of approximately 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Comparative Example 10>
To 34.5 parts by mass of the mixed solvent A, 61.5 parts by mass of the mixed solution 10 was added and thoroughly stirred and mixed, after which 4.0 parts by mass of Ecostage crosslinking agent was added and stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Comparative Example 10 with a solid content of approximately 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Comparative Example 11>
To 35.0 parts by mass of the mixed solvent A, 63.4 parts by mass of the mixed solution 1 was added and thoroughly stirred and mixed, after which 1.6 parts by mass of Ecostage crosslinking agent was added and stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Comparative Example 11 having a solid content of approximately 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Comparative Example 12>
To 31.5 parts by mass of the mixed solution A, 51.5 parts by mass of the mixed solution 1 was added and thoroughly stirred and mixed, after which 17.0 parts by mass of Ecostage crosslinking agent was added and stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Comparative Example 10 with a solid content of approximately 4.2%.

<Preparation of Coating Fluid for Forming Gas Barrier Resin Composition Layer of Comparative Example 13>
To 35.2 parts by mass of the mixed solvent A, 63.8 parts by mass of the mixed solution 11 was added, and the mixture was thoroughly stirred and mixed. Then, 1.0 part by mass of Ecostage crosslinking agent was added, and the mixture was stirred and mixed for about 15 minutes to obtain a coating solution for forming a gas barrier resin composition layer of Comparative Example 10 having a solid content of approximately 4.2%.

(Gas barrier laminate film of Example 1)
The above-mentioned gas barrier resin composition layer-forming coating liquid was applied by reverse gravure coating onto the inorganic thin film layer of a 12 μm-thick biaxially stretched polyester film on which a 10 nm-thick inorganic thin film layer of aluminum oxide had been formed, and the coating liquid was dried at 120° C. to form a gas barrier resin layer, thereby producing a gas barrier laminate film.
The rotation ratio of the reverse roll during reverse gravure coating was 1.1.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Example 2)
A gas barrier laminate film was prepared in the same manner as in Example 1, except that the rotation ratio of the reverse roll during reverse gravure coating was set to 1.5.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Example 3)
A gas barrier laminate film was prepared in the same manner as in Example 1, except that the rotation ratio of the reverse roll during reverse gravure coating was set to 2.0.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Example 4)
A gas barrier laminate film was produced in the same manner as in Example 1, except that the coating liquid for forming the gas barrier resin composition layer of Example 4 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Example 5)
A gas barrier laminate film was produced in the same manner as in Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Example 5 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Example 6)
A gas barrier laminate film was produced in the same manner as in Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Example 6 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Example 7)
A gas barrier laminate film was produced in the same manner as in Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Example 7 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 1)
A gas barrier laminate film was prepared in the same manner as in Example 1, except that the coating method for the gas barrier resin composition layer-forming coating solution was changed to a direct gravure coating method.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 2)
A gas barrier laminate film was prepared in the same manner as in Comparative Example 1, except that the stirring time of the coating liquid for forming the gas barrier resin composition layer was extended by an additional 45 minutes.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 3)
A gas barrier laminate film was produced in the same manner as in Example 1, except that the coating method for the gas barrier resin composition layer-forming coating liquid was changed to a bar coating method, and the coating liquid before coating was obtained by high-speed stirring with a homogenizer.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 4)
A gas barrier laminate film was prepared in the same manner as in Example 1, except that the rotation ratio of the reverse roll during reverse gravure coating was set to 0.5.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 5)
A gas barrier laminate film was prepared in the same manner as in Example 1, except that the rotation ratio of the reverse roll during reverse gravure coating was set to 2.5.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 6)
A gas barrier laminate film was produced in the same manner as in Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Comparative Example 6 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 7)
A gas barrier laminate film was produced in the same manner as in Comparative Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Comparative Example 7 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 8)
A gas barrier laminate film was produced in the same manner as in Comparative Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Comparative Example 8 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 9)
A gas barrier laminate film was produced in the same manner as in Comparative Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Comparative Example 9 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 10)
A gas barrier laminate film was produced in the same manner as in Comparative Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Comparative Example 10 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 11)
A gas barrier laminate film was produced in the same manner as in Comparative Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Comparative Example 11 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 12)
A gas barrier laminate film was produced in the same manner as in Comparative Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Comparative Example 12 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

(Gas barrier laminate film of Comparative Example 13)
A gas barrier laminate film was produced in the same manner as in Comparative Example 1, except that the coating liquid for forming a gas barrier resin composition layer of Comparative Example 13 was used as the coating liquid.
The thickness of the gas barrier resin layer after drying was about 0.3 μm.

The above results are shown in Tables 1 and 2.

From the above results, the actual gas barrier property evaluation of the OTR theoretical value for Examples 1 to 7, in which the coating method was changed to reverse gravure coating, and Comparative Example 6, was all 55% or more. It is believed that the high shear applied to the coating liquid during coating caused the inorganic layered compound to disperse sufficiently, resulting in the ideal maze effect. Comparative Example 6 was insufficient in terms of WVTR. This is believed to be because the resin component of the coating liquid used did not contain any component A, which contributes to water vapor barrier properties.

The actual value evaluation of the OTR gas barrier property theoretical value for Comparative Examples 1 to 5 and 8 to 10 was less than 30%. The reason for this is believed to be that in Comparative Examples 1 to 3 and 8 to 10, the coating method was not reverse gravure but direct gravure or bar coating, and high shear was not applied to the coating liquid during coating, resulting in insufficient dispersion of the inorganic layered compound. In Comparative Example 4, the rotation ratio of the reverse roll was too low, which resulted in unstable supply of the coating liquid, causing coating unevenness and an unstable coating film. In Comparative Example 5, the rotation ratio of the reverse roll was too high, which resulted in scratches in the deposition layer of the deposition film to be coated. In Comparative Example 7, both the OTR and WVTR were insufficient. This is believed to be because there was no absence of component D, which contributes to barrier properties. In Comparative Example 10, deterioration of the film appearance and deterioration of adhesion were confirmed. It is believed that the addition of too much component D caused the coating liquid to thicken and become unstable, making coating difficult and causing the film to become cloudy. It is also believed that the decrease in adhesion was caused by a decrease in the cohesive force of the film. A decrease in adhesion was confirmed in Comparative Example 11. This is believed to be due to the amount of component C, the crosslinking agent, being small relative to component B, the crosslinked portion, leaving uncrosslinked portions. In Comparative Example 12, both the OTR and WVTR were insufficient. This is believed to be due to the presence of an excessive amount of component C, the crosslinking agent, which reduced the amounts of components A and B, which contribute to barrier properties. A decrease in adhesion was confirmed in Comparative Example 13. This is believed to be due to the amount of component B, the crosslinked portion, being small, which reduced the number of crosslinked portions.

The present invention can provide a gas barrier laminate film and a gas barrier packaging bag that have higher gas barrier properties against oxygen than conventional ones. The gas barrier film of the present invention can be widely used for packaging applications that require high oxygen barrier properties, such as confectionery, household goods, electronic components, and pharmaceuticals, as well as industrial applications such as vacuum insulation materials.

Claims (8)

A gas barrier laminate film comprising an inorganic oxide thin film layer and a gas barrier resin composition layer laminated on at least one surface of a base film, the gas barrier resin composition layer containing a polyvinyl alcohol copolymer resin (component A) having a structural unit represented by the following chemical formula 1 in the molecule, a polyvinyl alcohol (co)polymer resin (component B) having a carbonyl group in the molecule, a hydrazine crosslinking agent (component C), and an inorganic layered compound (component D), and exhibiting a performance of 55% or more of the theoretical value (d2) of oxygen gas barrier property calculated by the following formula 1 from the oxygen gas barrier property (d1) of the polymer alone used and the thickness (W), length (L), and volume fraction (Vf) of the inorganic layered compound added, and the gas barrier resin composition layer satisfying the following conditions 1 to 3 .
Condition 1: When the mass of component A contained in the barrier coating agent which forms the gas barrier resin composition layer is taken as WA and the mass of component B contained in the barrier coating agent is taken as WB, WA/WB is 20/80 to 70/30.
Condition 2: When the mass of the component B is WB and the mass of the component C is WC, WB/WC is 95/5 to 70/30.
Condition 3: When the mass of the component D contained in the barrier coating agent is defined as WD, the ratio (WA+WB)/WD is 95/5 to 70/30.


(wherein _R1 and _R2 are each independently a hydrocarbon group having 1 to 3 carbon atoms.)

d2=d1+d1・L・Vf/2W... Formula 1 2. The gas barrier laminate film according to claim 1, wherein the component A is a saponification product of a copolymer of radical polymerizable monomers, the copolymer comprising a radical polymerizable monomer represented by the following chemical formula 2 and a vinyl ester monomer:

( _R1 and _R2 are each independently a hydrocarbon group having 1 to 3 carbon atoms, and _R3 and _R4 are each independently a hydrogen atom or a -CO- _R5 group (wherein _R5 is preferably a methyl group, a propyl group, a butyl group, a hexyl group, or an octyl group, and such an alkyl group may have a substituent such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, or a sulfonic acid group, as necessary.) 3. The gas barrier laminate film according to claim 1, wherein the component A is a polyvinyl alcohol copolymer resin represented by the following chemical formula 3:

(wherein _R1 and _R2 are defined as above, and X is derived from the molecular structure of the radical polymerizable monomer used as a copolymerization component and represents a structural unit that does not fall under the other two structural units.)
l, m, and n represent the average number of each structural unit per molecule, and satisfy the relationships: l+m+n=300 to 4000, l/(l+m+n)=0.001 to 0.2, m/(l+m+n)=0.8 to 0.99, and n/(l+m+n)=0 to 0.1. 4. The gas barrier laminate film according to claim 1 , wherein the component B is a vinyl alcohol-based (co)polymer resin which satisfies the following condition 4 and/or condition 5:
Condition 4: A saponification product of a copolymer of radical polymerizable monomers including a vinyl ester monomer and a carbonyl group-containing radical polymerizable monomer.
Condition 5: The polymer is an acetoacetylated product of a saponified (co)polymer of a radical polymerizable monomer containing a vinyl ester monomer. The gas barrier laminate film according to any one of claims 1 to 4 , wherein the component B is a polyvinyl alcohol-based (co)polymer resin containing, in the molecule, a structural unit represented by the following chemical formula 4 and/or a structural unit represented by the following chemical formula 5:

(wherein _R6 is hydrogen or a methyl group.)
6. The gas barrier laminate film according to claim 1, wherein the component B is a polyvinyl alcohol-based (co)polymer resin represented by the following chemical formula 6:

(wherein _R6 is hydrogen or a methyl group. Also, Y is derived from the molecular structure of the radically polymerizable monomer used as a copolymerization component and represents a structural unit that does not fall into the other three structural units.
o+p+q+r is 300 to 4000, and the following relationships are satisfied: (o+p)/(o+p+q+r)=0.001 to 0.25, q/(o+p+q+r)=0.75 to 0.999, r/(o+p+q+r)=0 to 0.2.) 7. The gas barrier laminate film according to claim 1, wherein the inorganic oxide thin film layer contains at least one type of inorganic oxide including silicon oxide and/or aluminum oxide. A gas barrier packaging bag using the gas barrier laminate film according to any one of claims 1 to 7 , the gas barrier packaging bag being arranged in the following order from the outside of the bag: a base film layer, an inorganic oxide thin film layer, and a gas barrier resin composition layer.