JPH10725A - Gas-barrier laminate for packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminate for packaging, which is excellent in transparency and has high gas-barrier properties by a method wherein a printed layer, a thin film, which is made of inorganic oxide and has the thickness of 5-300nm are laminated in the order named at least on one side of a base material made of transparent plastic material. SOLUTION: Four color printing is applied by a gravure coat process with urethane-based inks as a printed layer 2 on one side of a base material made of a biaxially oriented polyethylene terephthalate film having the thickness of 12μm. Next, as a transparent primer layer 3, the resin having the following composition: resin: polyester/isocyanate-based, compound ratio: OH group (polyester): NOC group (isocyanate)=1/8 (equivalent ratio), thickness: 0.2μm, solvent: toluence/methyl ethyl keton=5/5, is formed by the gravure coat process. Further, a thin inorganic oxide film layer 4 is formed by vacuum evaporating silicon oxide by the thickness of about 40nm with a resistant-heating system vacuum evaporating device. Thus, a laminate for packaging excellent in interfacial adhesion and smotthness is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging laminate used in the field of packaging foods, non-foodstuffs, pharmaceuticals, etc., and more particularly to the field of packaging containing printing of characters and pictures. .

[0002]

2. Description of the Related Art In recent years, packaging materials used for packaging foods, non-foodstuffs, pharmaceuticals, etc., include oxygen and water vapor that pass through the packaging materials in order to suppress deterioration of contents and maintain their functions and properties. In addition, it is necessary to prevent the influence of a gas that alters the contents, and it is required to have a gas barrier property for blocking these gases. Therefore, conventionally, a packaging material using a metal foil made of a metal such as aluminum, which is less affected by temperature, humidity, and the like, as a gas barrier layer has been generally used.

[0003] However, a packaging material using a metal foil made of a metal such as aluminum has excellent gas barrier properties, but the contents cannot be checked through the packaging material. However, there is a problem in that the metal detector has to be disposed of, and a metal detector cannot be used.

[0004] Further, when a printing layer such as a character or a picture is provided, there has been a problem that the process becomes complicated since printing is performed on a different base material because the printing layer is opaque.

Therefore, as a packaging material which overcomes these drawbacks, for example, US Pat.
A film formed by depositing an inorganic oxide such as silicon oxide, aluminum oxide, and tin oxide on a polymer film by a forming means such as a vacuum evaporation method or a sputtering method as described in -28017 and the like. Is being developed. These films are known to have transparency and gas barrier properties against oxygen, water vapor and the like, and are considered suitable as packaging materials having both transparency and gas barrier properties that cannot be obtained with metal foils and the like. .

[0006]

However, when characters, pictures, and the like are printed on the vapor deposition surface of the vapor deposition film described above, defects such as cracks and the like occur in the vapor deposition film due to contraction of the printing ink in a drying process after the printing, and a gas barrier. There is a problem that the properties are deteriorated.

[0007] Further, if printing is first performed on a substrate before vapor deposition and then vapor deposition is performed, a smooth coating film cannot be obtained by printing, so that the gas barrier property of the vapor deposited film is poor. Since the adhesion of the layer is weak, when the contents are filled and stored, there is a problem that peeling occurs from the interface and delamination or the like occurs.

[0008] That is, the conditions for use as a packaging material include transparency enough to allow the contents to be directly seen through, high gas barrier properties for blocking gases that affect the contents, and printing. There is a demand for a material that does not deteriorate the gas barrier properties and adhesion and that requires less labor in processing, but at present, no packaging material that satisfies all of these has been found.

Therefore, the present invention provides a highly practical packaging laminate which is excellent in transparency, has high gas barrier properties, does not deteriorate in gas barrier properties and adhesion even when printing, and requires little processing. The purpose is to provide.

[0010]

Means for Solving the Problems The present invention has been achieved to achieve the above-mentioned object, and the invention described in claim 1 is to provide a substrate made of a transparent plastic material on at least one side of a printing layer, a transparent primer layer, A gas barrier laminate for packaging, characterized by sequentially laminating thin film layers made of an inorganic oxide having a thickness of 5 to 300 nm.

According to a second aspect of the present invention, based on the first aspect, a water-soluble polymer is further provided on the thin film layer made of the inorganic oxide as a gas barrier film layer, and (a) one or more metal alkoxides. And a hydrolyzate thereof or (b) tin chloride, coated with a coating agent having an aqueous solution or a water / alcohol mixture as a main component, and laminated by heating and drying. It is a gas barrier laminate.

According to a third aspect of the present invention, based on the first and second aspects, the transparent primer layer is a polyester resin or a mixture of the resin and a mixed resin, and the mixed resin is (a) an isocyanate. 1 selected from the group consisting of an epoxy resin, (b) an epoxy resin, and (c) a melamine resin.
A gas barrier laminate for packaging characterized by being a mixture of at least two or more kinds.

According to a fourth aspect of the present invention, based on the first to third aspects, the mixed resin is an isocyanate-based resin, and the mixing ratio of the polyester resin and the isocyanate-based resin is equivalent ratio (OH group of the polyester). ): (NCO group of isocyanate) 1: 0.5 to 1:20, which is a gas barrier laminate for packaging.

According to a fifth aspect of the present invention, based on the first to fourth aspects, the transparent primer layer has a thickness of 0.1%.
A gas barrier laminate for packaging, wherein the thickness is in the range of 1.0 μm to 1.0 μm.

According to a sixth aspect of the present invention, based on the first to fifth aspects, the inorganic oxide is aluminum oxide,
A packaging gas barrier laminate characterized by being silicon oxide or a mixture thereof.

A seventh aspect of the present invention is the packaging gas barrier laminate according to the second aspect, wherein the water-soluble polymer is polyvinyl alcohol.

According to an eighth aspect of the present invention, based on the second and seventh aspects, the metal alkoxide is tetraethoxysilane, triisopropoxyaluminum, or a mixture thereof. It is.

The laminate of the present invention is a thin film comprising an inorganic oxide having excellent gas barrier properties after forming a transparent primer layer having excellent adhesion and smoothness on a printing layer provided on a transparent plastic substrate. Because it has a configuration in which layers are laminated, it is excellent in transparency and adhesion, gas barrier properties even after printing,
It is a highly practical packaging laminate that can be processed on the same base material.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view illustrating a gas barrier laminate for packaging according to the present invention.

First, the packaging gas barrier laminate of the present invention shown in FIG. 1 will be described. A substrate 1 in FIG. 1 is a film made of a transparent plastic material, on which a printing layer 2, a transparent primer layer 3, and a thin film layer 4 made of an inorganic oxide are sequentially formed. Further, a gas barrier coating layer 5 is formed on the inorganic oxide thin film layer 4 in order to obtain a more advanced gas barrier packaging material.
May be formed.

The above-mentioned substrate 1 is a transparent plastic material, and is preferably a transparent film in order to make use of the transparency of the thin film layer 4 made of an inorganic oxide. For example, polyethylene terephthalate (PET), polyester films such as polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, polystyrene films, polyamide films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, polyimide films, and the like are used. Either stretched or unstretched may be used, and those having mechanical strength and dimensional stability are preferred. These are processed into a film and used. Particularly, polyethylene terephthalate arbitrarily stretched in the biaxial direction is preferably used. This substrate 1
Various known additives and stabilizers, for example, antistatic agents, UV inhibitors, plasticizers, lubricants, etc. may be used on the surface of the surface, and in order to improve the adhesion to the thin film, Corona treatment, low-temperature plasma treatment, ion bombardment treatment, or chemical treatment, solvent treatment, or the like may be performed.

Although the thickness of the substrate 1 is not particularly limited, it is suitable as a packaging material, other layers may be laminated, the printing layer 2, the transparent primer layer 3, and the inorganic oxide thin film. Considering the processability when forming the layer 4 and the gas barrier coating layer 5, it can be said that practically, the thickness is preferably in the range of 3 to 200 μm and 6 to 30 μm depending on the application.

Further, in consideration of mass productivity, it is desirable to use a long film so that each layer can be formed continuously.

The printed layer 2 formed on the substrate 1 is provided for the purpose of forming characters, pictures, etc. in order to practically use the laminate of the present invention as a packaging bag.

In order to achieve the above object, the printing layer 2 can be formed of a known ink binder resin such as urethane, acrylic, nitrocellulose, rubber and vinyl chloride. Printing inks and the like, to which various pigments, extenders, and additives such as plasticizers, drying agents, and stabilizers are added.

As a method of forming the print layer 2, for example, a known printing method such as an offset printing method, a gravure printing method, a silk screen printing method, or a known coating method such as a roll coat, a knife edge coat, or a gravure coat is used. Can be used. The thickness varies depending on the type of the packaging material and the required quality and is not particularly limited, but is generally 0.1 to 4.0 μm.
m.

In this case, the printing layer 2 may be provided on the entire surface, but may be provided partially on the design. At this time, it is preferable that the printing layer is provided on the entire surface in order to uniformly shrink the ink. However, even when the printing layer 2 is partially provided, the thin film layer 4 and the printing layer 2 are in direct contact with each other. Therefore, deterioration is not easily caused.

The transparent primer layer 3 of the present invention is provided on the printing layer 2 to improve the adhesion between the printing layer 2 and the thin film layer 4 made of an inorganic oxide, and to smooth the unevenness of the printing layer to make it uniform. The purpose is to obtain a thin film layer 4 made of an inorganic oxide.

In order to achieve the above object, the primer resin can be used as a single polyester resin or a mixture of the polyester resin and one or more kinds of mixed resins selected from isocyanate resins, epoxy resins and melamine resins. Must be a mixture of

The above polyester resins are terephthalic acid, isophthalic acid, phthalic acid, methylphthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, succinic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid , Hexahydrophthalic acid and acid raw materials such as reactive derivatives thereof, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol,
1,4-cyclohexanedimethanol, neopentyl glycol, isopentyl glycol, bishydroxyethyl terephthalate, hydrogenated bisphenol A, alkylene oxide adduct of hydrogenated bisphenol A, trimethylolethane, trimethylolpropane, glycerin,
Those produced by known methods from alcohol raw materials such as pentaerythritol and 2,2,4-trimethylpentane-1,3-diol can be used, but are not particularly limited thereto.

The mixed resin added to the polyester resin is added in order to further enhance the adhesion, and mainly functions as a crosslinking agent or a curing agent. In order to achieve this, as a mixed resin, isocyanate resins such as tolylene diisocyanate (TDI), xylene diisocyanate (XDI), and hexadiisocyanate (MDI), bisphenol A diglycine ether type epoxy and hydrogenated bisphenol type epoxy Epoxy resins, melamine resins, and mixtures of one or more of these. Among them, isocyanate resin (particularly, TDI) is preferred because it has the best adhesion.

The mixing ratio of the polyester resin and the mixed resin may be such that the isocyanate group, the epoxy group, the amino group and the like are contained in an equivalent amount or more with respect to the OH group and the COOH group of the polyester resin. For example, when an isocyanate-based resin alone is used as the mixed resin, the mixing ratio of the polyester resin and the isocyanate-based resin is equivalent ratio of (OH group of polyester) :( NCO group of isocyanate) and is 1:
It is desirable to be in the range of 0.5 to 1:20. If it is less than the equivalent, poor curing and insufficient cross-linking will result in a problem in adhesion. However, adding too much is not preferable because the added resin does not react and adversely affects the remaining film. A well-known method can be used for the mixing method and is not particularly limited.

The organic solvent for dissolving the primer resin is not particularly limited as long as it can dissolve the resin, and examples thereof include esters such as ethyl acetate and butyl acetate, and methyl ethyl ketone and methyl isobutyl ketone. Aromatic hydrocarbons such as ketones, toluene and xylene may be used alone or arbitrarily blended.
Preferably, a mixture of toluene and methyl ethyl ketone is preferable from the viewpoint of coating film processing and odor.

Various additives such as 3
Curing accelerators such as quaternary amines, imidazole derivatives, carboxylic acid metal salt compounds, quaternary ammonium salts, and quaternary borophonium salts; antioxidants such as phenol-based, sulfur-based, and phosphite-based agents, leveling agents, and flow regulators , A catalyst, a crosslinking reaction accelerator, a filler and the like can be added.

The thickness of the transparent primer layer 3 is not particularly limited as long as a uniform coating film can be formed, but is generally preferably in the range of 0.01 μm to 1.0 μm. If the thickness is less than 0.01 μm, it is difficult to obtain a uniform coating film, so that the smoothness is poor and the adhesion may be reduced. If the thickness exceeds 1.0 μm, the coating film cannot maintain flexibility because of the thickness,
It is not preferable because the coating film may be cracked by external factors. Particularly preferred is a range of 0.1 to 1.0 μm.

The method for forming the transparent primer layer 3 is as follows.
For example, a known printing method such as an offset printing method, a gravure printing method, or a silk screen printing method, or a known coating method such as a roll coat, a knife edge coat, or a gravure coat can be used. The drying conditions may be those generally used. In some cases, coating may be performed using the last unit in the printing press.

The thin film layer 4 made of an inorganic oxide is made of a deposited film of an inorganic oxide such as aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof.
Any material may be used as long as it has transparency and gas barrier properties such as oxygen and water vapor. Among them, aluminum oxide and silicon oxide are particularly preferable. However, the thin film layer 4 of the present invention
Is not limited to the inorganic oxides described above, and any material that meets the above conditions can be used.

The optimum condition of the thickness of the thin film layer 4 depends on the type and constitution of the inorganic compound used.
It is desirable to be within the range of -300 nm, and the value is appropriately selected. However, if the film thickness is less than 5 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. When the thickness exceeds 300 nm, the thin film cannot maintain flexibility,
There is a possibility that the thin film may be cracked by external factors such as bending and pulling after film formation. Preferably, 10-1
It is in the range of 50 nm.

There are various methods for forming the thin film layer 4 made of an inorganic oxide on the transparent primer layer 3, which can be formed by an ordinary vacuum deposition method. A plating method, a plasma vapor deposition method (CVD), or the like can also be used. However, in consideration of productivity, the vacuum deposition method is currently the most excellent. The heating means of the vacuum evaporation apparatus by the vacuum evaporation method is preferably an electron beam heating method, a resistance heating method, or an induction heating method. It is also possible to use a method or an ion beam assist method. In addition, in order to increase the transparency of the deposited film, reactive deposition in which oxygen gas or the like is blown in the deposition may be used.

The gas barrier coating layer 5 is provided on the inorganic oxide thin film layer 4 and is provided when a high gas barrier property is required depending on the required quality. It is composed of an aqueous solution or a water / alcohol mixed solution containing at least one of at least one of metal alkoxides and hydrolysates or (b) tin chloride. Mineralize a solution in which a water-soluble polymer and tin chloride are dissolved in an aqueous (water or water / alcohol mixture) solvent, or a solution in which a solution obtained by directly or beforehand hydrolyzing a metal alkoxide is mixed. It is formed by coating and heating and drying the thin film layer 4 made of an oxide. Each component contained in the coating agent will be described in more detail.

The water-soluble polymer used for the coating agent in the present invention includes polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like. In particular, when polyvinyl alcohol (hereinafter, referred to as PVA) is used as a coating agent for the laminate of the present invention, the gas barrier properties are most excellent. The PVA referred to here is generally obtained by saponifying polyvinyl acetate, and includes a range from so-called partially saponified PVA in which acetic acid groups remain to several tens% to complete PVA in which only a few% of acetic acid groups remain. However, there is no particular limitation.

Tin chloride is stannous chloride (SnCl ₂ ),
Stannic chloride (SnCl ₄ ) or a mixture thereof may be used, and either anhydrous or hydrated can be used.

Further, the metal alkoxide is tetraethoxy.
Silane [Si (OC_Two H_Five )_Four ], Triisopropoxy
Aluminum [Al (O-2'-C_Three H₇ )_Three ]
General formula, M (OR)_n(M: Si, Ti, Al, Zr, etc.
Metal, R: CH_Three , C_Two H _Five Such as an alkyl group)
Things. Among them, tetraethoxysilane, triiso
After propoxyaluminum is hydrolyzed, it is dissolved in aqueous solvent.
Is relatively stable in this case.

Each of the above-mentioned components can be added to the coating agent alone or in combination of several components. Further, as long as the gas barrier properties of the coating agent are not impaired, isocyanate compounds, silane coupling agents, dispersants, and stabilizers Known additives such as a viscosity modifier and a coloring agent can be added.

For example, an isocyanate compound added to a coating agent has two or more isocyanate groups (NCO groups) in its molecule. For example, tolylene diisocyanate (TDI), triphenylmethane triisocyanate (TTI) ), Tetramethylxylene diisocyanate (hereinafter, TMXDI), and polymers and derivatives thereof.

As a method of applying the coating agent, conventionally known means such as a commonly used dipping method, roll coating method, screen printing method, spray method and the like can be used. The thickness of the coating varies depending on the type of coating agent and processing conditions, but the thickness after drying is 0.01μ.
It is sufficient that the thickness is at least m, but if the thickness is at least 50 μm, cracks are likely to occur in the film, so that the thickness is preferably in the range of 0.01 to 50 μm.

Further, another layer can be laminated on the gas barrier coating layer 5. For example, it is a heat seal layer. The heat seal layer is used for an adhesive portion when forming a bag-like package or the like, for example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester Resins such as copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, and metal crosslinked products thereof are used. The thickness is determined according to the purpose, but is generally in the range of 15 to 200 μm. As a forming method, a method of laminating a film-like material made of the above resin by a dry laminating method of bonding using an adhesive such as a two-component curable urethane resin or a non-solvent laminating method of bonding by using a non-solvent adhesive is used. Any of known methods such as an extrusion lamination method in which the above resin is heated and melted and extruded into a curtain shape and pasted together can be used.

[0048]

EXAMPLES The gas barrier laminate for packaging according to the present invention will be further described with reference to specific examples.

<Example 1> As the substrate 1, a thickness of 12 μm
On one side of the biaxially stretched polyethylene terephthalate (PET) film, four colors (red, yellow, black, and white) were printed by a gravure coating method using a urethane-based ink as the printing layer 2. Next, a resin having the following composition was formed as a transparent primer layer 3 by a gravure coating method. Resin: polyester / isocyanate compounding ratio: OH group (polyester) / NCO group (isocyanate) = 1/8 (equivalent ratio) Thickness: 0.2 μm Solvent: toluene / methyl ethyl ketone = 5/5 Further transparent primer layer 3 Silicon oxide was deposited to a thickness of about 40 nm by a vacuum deposition apparatus using a resistance heating method (not shown) to form an inorganic oxide thin film layer 4, thereby obtaining a packaging gas barrier laminate of the present invention.

<Example 2> The procedure of Example 1 was repeated, except that a coating agent having the following composition was formed on the inorganic oxide thin film layer 4 as the gas barrier coating layer 5 by a gravure coating method to a thickness of 0.3 μm. A packaging gas barrier laminate of the present invention was obtained. (Composition of coating agent) Mixing ratio of liquid and liquid (wt
%) And hydrochloric acid (0.1N) 89.6 g was added to 10.4 g of tetraethoxysilane,
Solid content 3 wt% (SiO 2
3w hydrolysis solution of polyvinyl alcohol ₂ equivalent)
t% water / isopropyl alcohol solution (water: isopropyl alcohol weight ratio 90:10))

<Example 3> In Example 1, metal aluminum was evaporated as the inorganic oxide thin film layer 4 by a vacuum evaporation apparatus using an electron beam heating method (not shown), and an oxygen gas was introduced thereinto to oxidize to a thickness of 20 nm. A packaging gas barrier laminate of the present invention was obtained in the same manner except that an aluminum thin film layer was formed.

Example 4 A gas barrier laminate for packaging according to the present invention was obtained in the same manner as in Example 1, except that the following resin was used as the transparent primer layer 3. Resin: polyester / isocyanate compounding ratio: OH group (polyester) / NCO group (isocyanate) = 1/4 (equivalent ratio) Thickness: 0.5 μm Solvent: toluene / methyl ethyl ketone = 5/5

Comparative Example 1 A laminate was obtained in the same manner as in Example 1, except that the transparent primer layer 3 was not provided.

<Comparative Example 2> In Example 1, the printing layer 2
Was obtained on the inorganic oxide thin film layer 3 in the same manner as above.

<Test 1> For the examples and comparative examples,
The oxygen transmission rate (cc / m ² / day) of the laminate was measured. Table 1 shows the results.

<Test 2> For the examples and comparative examples,
A 30 μm-thick polypropylene film was laminated by a dry lamination method via a two-component curable urethane-based adhesive, and then a four-sided pouch was prepared and filled with 30 g of toothpaste as the content. For evaluation of adhesion, the pouch was stored in an atmosphere of 40 ° C.-90% RH, and the occurrence of delamination was confirmed. Table 1 shows the results.

[0057]

[Table 1]

Compared to the examples, the comparative example has a poor oxygen permeability and causes delamination due to insufficient adhesion, whereas the examples have excellent oxygen permeability and no delamination or the like.

[0059]

As described above, according to the present invention, since the transparent primer layer having excellent adhesion and smoothness is provided between the printing layer and the inorganic oxide thin film layer, the interface at the interface is excellent. In addition, since it is excellent in smoothness affecting gas barrier development, it is a highly practical packaging laminate excellent in gas barrier properties even after vapor deposition of an inorganic oxide thin film layer.

[0060]

[Brief description of the drawings]

FIG. 1 is a cutaway sectional view of a packaging gas barrier laminate of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent plastic base material 2 Printing layer 3 Transparent primer layer 4 Inorganic oxide thin film layer 5 Gas barrier coating layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C08L 61/20 LNP C08L 61/20 LNP 67/00 LPK 67/00 LPK 75/02 NGJ 75/02 NGJ

Claims (8)

[Claims] (1) a printing layer, a transparent primer layer, a thickness of 5 to 30 on at least one side of a substrate made of a transparent plastic material;
A gas barrier laminate for packaging, characterized by sequentially laminating thin film layers made of 0 nm inorganic oxide. 2. The method according to claim 1, further comprising, as a gas barrier film layer, a water-soluble polymer on the thin film layer comprising an inorganic oxide;
(A) one or more metal alkoxides and hydrolysates thereof, or (b) tin chloride, a coating agent containing an aqueous solution or a water / alcohol mixture as a main component, and drying by heating. The gas barrier laminate for packaging according to claim 1, wherein the laminate is laminated. 3. The transparent primer layer is a polyester resin or a mixture of the resin and a mixed resin, wherein the mixed resin comprises (a) an isocyanate resin, (b) an epoxy resin, and (c) a melamine resin. The gas barrier laminate for packaging according to claim 1, wherein the laminate is at least one mixture selected from the group consisting of: 4. The mixed resin is an isocyanate resin, and the mixing ratio of the polyester resin and the isocyanate resin is equivalent to (OH group of polyester) :( NCO group of isocyanate) in the range of 1: 0.5-1. : 20. The gas barrier laminate for packaging according to any one of claims 1 to 3, wherein: 5. The transparent primer layer having a thickness of 0.1 to 0.1.
The gas barrier laminate for packaging according to any one of claims 1 to 4, wherein the thickness is in a range of 1.0 µm. 6. The packaging gas barrier laminate according to claim 1, wherein the inorganic oxide is aluminum oxide, silicon oxide, or a mixture thereof. 7. The package according to claim 2, wherein the water-soluble polymer is polyvinyl alcohol. 8. The method according to claim 2, wherein the metal alkoxide is tetraethoxysilane or triisopropoxyaluminum, or a mixture thereof.
The tightly adhered gas barrier laminate for packaging according to the above.