JP7014283B2 - Laminate - Google Patents

Description

The present invention relates to a laminated film used in the packaging field of foods, pharmaceuticals, industrial products and the like. More specifically, the present invention relates to a laminated film capable of enhancing the interlayer adhesion of the inorganic thin film layer and exhibiting good gas barrier property, adhesion, and bending resistance when the gas barrier laminated film provided with the inorganic thin film layer is prepared.

Packaging materials used in foods, pharmaceuticals, etc. must have the property of blocking gases such as oxygen and water vapor, that is, gas barrier properties, in order to suppress the oxidation of proteins and fats, maintain the taste and freshness, and maintain the efficacy of pharmaceuticals. It has been demanded. Further, gas barrier materials used for electronic devices such as solar cells and organic ELs and electronic parts require higher gas barrier properties than packaging materials such as foods.

Conventionally, in food applications that require blocking of various gases such as water vapor and oxygen, the surface of a base film made of plastic is made of a metal thin film made of aluminum or the like and an inorganic oxide such as silicon oxide or aluminum oxide. A gas barrier laminate having an inorganic thin film formed is generally used. Among them, those having a thin film (inorganic thin film layer) of an inorganic oxide such as silicon oxide, aluminum oxide, and a mixture thereof are widely used because they are transparent and the contents can be confirmed.

However, in the above gas barrier laminate, the gas barrier property deteriorates due to physical damage to the inorganic thin film layer due to bending load in the post-processing process of packaging materials such as printing, laminating, and bag making, as well as in the transportation and distribution processes. I have a problem. Once the inorganic thin film layer is damaged in the processing process, there is a concern that the gas barrier property will be significantly deteriorated by the subsequent wet heat treatment such as boiling and retort treatment. Further, the film having poor interlayer adhesiveness between the thin-film vapor deposition layer and the resin in contact with the film has a problem that peeling occurs due to a bending load, the barrier property is deteriorated, and the contents leak out.

On the other hand, as a method for improving the deterioration of the gas barrier laminate on which the inorganic thin film is formed, various aqueous polyurethane resins, polyester resins, or between the polyester base film and the inorganic thin film layer formed by, for example, the vapor deposition method, or A method of providing a coating layer composed of a mixture of polyurethane and polyester has been proposed (for example, Patent Document 1). Further, it has been reported that a coating layer made of an oxazoline group-containing water-soluble polymer is provided in order to improve the water resistance of the coating layer under moist heat (see, for example, Patent Document 2). Providing the coating layer between the base film and the inorganic thin film can be continuously performed during the film formation of the base material, and a greater cost reduction can be expected than forming a protective layer on the inorganic thin film. However, in the case of the above configuration, the coating layer itself does not have a gas barrier property, and the contribution to the gas barrier property is largely due to only the inorganic thin film layer, so that there is a problem that the gas barrier property is not sufficient.

To solve the above problems, attempts have been made to provide a protective layer having a gas barrier property on the inorganic thin film. For example, a water-soluble polymer, an inorganic layered compound, and a metal alkoxide or a hydrolyzate thereof are coated on an inorganic thin film, and a composite of the inorganic substance containing the inorganic layered compound and the water-soluble polymer on the inorganic thin film by the sol-gel method is used. Methods of forming the body have been proposed. According to this method, excellent properties are exhibited even after wet heat treatment, but the stability of the liquid to be applied to the coating is low, so that even when the coating is started and ended (for example, an industrially distributed roll film is used). For example, there are problems that the characteristics differ between the outer peripheral part and the inner peripheral part of the roll, the characteristics differ due to a slight difference in the temperature of drying and heat treatment in the film width direction, and the quality differs greatly depending on the manufacturing environment. Was there. Furthermore, since the film coated by the sol-gel method has poor flexibility, it has been pointed out that when the film is bent or impacted, pinholes and defects are likely to occur and the gas barrier property is deteriorated.

Against this background, it is desired to improve the ability to form a resin layer on an inorganic thin film layer by a coating method that does not involve a sol-gel reaction, that is, a coating method that mainly uses a resin and involves a cross-linking reaction at the time of coating. rice field. Examples of the gas barrier laminate with such improvements include a gas barrier laminate in which a resin layer containing an inorganic layered compound having a specific particle size and aspect ratio is coated on the inorganic thin film, and silane coupling on the inorganic thin film. Examples thereof include a gas barrier laminate coated with a barrier resin containing an agent, and a laminate coated with a metaxylylene group-containing polyurethane on an inorganic thin film (see, for example, Patent Document 3).

However, any of the above-mentioned methods is a gas barrier film that is excellent in production stability and economy during manufacturing, can maintain good barrier properties and adhesiveness even after harsh wet heat treatment, and has appropriate bending resistance. Was not obtained at present.

Japanese Unexamined Patent Publication No. 2-50837 Japanese Patent No. 5560708 Japanese Patent No. 4524463 Japanese Unexamined Patent Publication No. 11-179836

In the above-mentioned Patent Document 2, since the aim is to maintain the retort-resistant barrier performance in particular, improvement of the gas barrier property before the treatment has not been studied. Further, in Patent Document 3, the humidity dependence of oxygen permeability has been investigated, and each of them showed good values. However, regarding gas barrier property, adhesiveness, and bending resistance after harsh wet heat treatment such as retort boil. Was not considered.

The present invention has been made against the background of the problems of the prior art, and when a gas barrier laminated film having an inorganic thin film layer is formed, the gas barrier property of oxygen and water vapor is obtained even after normal and wet heat treatment. Further, it has been set as an issue to provide a laminated film having excellent adhesiveness between layers, having appropriate bending resistance, easy to manufacture, and excellent in economy.

The present inventors have improved the gas barrier performance before treatment and severe moisture by forming a laminated film in which the inorganic thin film layer is sandwiched between a specific coating layer having excellent flexibility and adhesiveness and a specific barrier protective layer. We have found that the barrier properties and adhesiveness can be maintained even after heat treatment, and completed the present invention.

That is, the present invention has the following configuration.
(1) A coating layer is provided on one side of a polyester base film, and the coating layer comprises a resin composition for a coating layer containing a resin having an oxazoline group as a constituent component, and has an inorganic thin film layer on the coating layer. At the same time, a protective layer having a urethane resin and an adhesion amount of 0.15 to 0.60 g / m ² is provided on the inorganic thin film layer, and the total reflection infrared absorption spectrum on the coating layer surface side of the laminated film is 1530 ±. The ratio (P1 / P2) of the peak intensity (P1) having the absorption maximum in the region of 10 cm ^-1 and the peak intensity (P2) having the absorption maximum in the region of 1410 ± 10 cm ^-1 is in the range of 1.5 to 3.5. The heat-sealable resin layer is laminated on the laminated film which is inside and has an oxygen permeability of 5 ml / m ² · d · MPa or less under the condition of 23 ° C. × 65% RH. Laminated body.
(2) The laminate according to (1), which is used as a packaging material.

According to the present invention, when a gas barrier laminated film provided with an inorganic thin film layer is formed, it exhibits excellent gas barrier properties not only under normal conditions but also after undergoing harsh wet heat treatment such as retort treatment. Further, it is possible to provide a laminated film that exhibits good laminating strength (adhesion) without delamination. Moreover, since the laminated film of the present invention can be easily manufactured with few processing steps, it is excellent in both economic efficiency and production stability, and it is possible to provide a gas barrier film having uniform characteristics.

The laminated film of the present invention is obtained by providing a coating layer, an inorganic thin film layer, and a protective layer on at least one surface of a polyester base film. First, the polyester base film will be described, and then the coating layer, the inorganic thin film layer, and other layers to be laminated on the polyester base film will be described.

[Polyester base film]
As the polyester base film (hereinafter sometimes referred to as “base film”) used in the present invention, for example, polyester is melt-extruded and, if necessary, stretched, cooled, and heat-fixed in the longitudinal direction and / or the width direction. Can be used. As the polyester, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate and the like are preferable in terms of heat resistance, step stability and transparency, and in particular, polyethylene terephthalate and polyethylene terephthalate are copolymerized with other components. Polymers are preferred.

As the base film, a film having an arbitrary film thickness can be used according to a desired purpose and application such as mechanical strength and transparency, and the film thickness is not particularly limited, but is usually 5 to 250 μm. Is recommended, and when used as a packaging material, it is preferably 10 to 60 μm.
The transparency of the base film is not particularly limited, but when it is used as a packaging material that requires transparency, it is desirable that the base film has a light transmittance of 50% or more.

The base film may be a single-layer film made of one kind of polyester, or may be a laminated film in which two or more kinds of polyester films are laminated. The type of laminated body, the number of laminated bodies, the laminating method, and the like in the case of forming a laminated film are not particularly limited, and can be arbitrarily selected from known methods according to the purpose.
Further, the base film may be subjected to surface treatment such as corona discharge treatment, glow discharge, flame treatment, and surface roughening treatment as long as the object of the present invention is not impaired, and a known anchor coat may be applied. Processing, printing, decoration, etc. may be applied.

[Coating layer]
The coating layer in the present invention contains a resin having an oxazoline group. In particular, it is preferable that an unreacted oxazoline group is present in the coating layer. The oxazoline group has a high affinity with inorganic thin films such as metal oxides, and can react with oxygen-deficient portions of inorganic oxides and metal hydroxides generated when the inorganic thin film layer is formed, so that it has strong adhesion to the inorganic thin film layer. Is shown. Further, the unreacted oxazoline group present in the coating layer can react with the carboxylic acid terminal generated by the hydrolysis of the base film and the coating layer to form a crosslink, and the water resistance of the coating layer can be maintained. ..

Further, by coexisting the unreacted oxazoline group portion and the reacted crosslinked portion in the coating layer, a film having water resistance and flexibility is obtained. Therefore, when a load such as bending is applied, the stress on the inorganic thin film layer can be relaxed, and as a result, the deterioration of the gas barrier property can be suppressed.

A coating layer made of only a resin having an oxazoline group can exhibit moisture heat treatment resistance, but the coating layer itself has a slightly insufficient cohesive force in a harsh wet heat treatment for a longer period of time and at a high temperature. Damage to the inorganic thin film layer due to its own deformation may be unavoidable. Therefore, in the present invention, it is preferable to further contain an acrylic resin so that the coating layer can sufficiently withstand even more severe wet heat treatment treatment. By containing the acrylic resin, the cohesive force of the coating layer itself is improved, and as a result, the water resistance is enhanced.

In the present invention, the coating layer resin composition is further mixed with a urethane resin, particularly a urethane resin having a carboxylic acid group, so that the moisture resistance and heat treatment resistance of the coating layer can be further enhanced. That is, by reacting the carboxylic acid group and the oxazoline group in the urethane resin, the coating layer becomes a layer having the flexibility of the urethane resin while being partially crosslinked, and stress relaxation of the inorganic thin film is performed at a higher level. It can be carried out.

By providing the above coating layer, the laminated film of the present invention is a laminated body provided with an inorganic thin film layer, but according to the above aspect, the gas barrier property and interlayer adhesiveness of the inorganic thin film layer are maintained even after a wet heat treatment such as retort pouch. At the same time, it also has an appropriate bending resistance.

Next, the constituent components of the resin composition for the coating layer forming the coating layer will be described in detail.
(Resin (A) having an oxazoline group)
The coating layer of the present invention contains a resin having an oxazoline group. As the resin having an oxazoline group, for example, a polymerizable unsaturated monomer having an oxazoline group is used together with other polymerizable unsaturated monomers by a conventionally known method (for example, solution polymerization, emulsion polymerization, etc.). Examples thereof include a polymer having an oxazoline group obtained by copolymerizing.

Examples of the polymerizable unsaturated monomer having an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-. Examples thereof include isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like. These may be used alone or in combination of two or more.

Examples of other polymerizable unsaturated monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth). Alkyl or cycloalkyl ester of (meth) acrylic acid having 1 to 24 carbon atoms such as acrylate, lauryl (meth) acrylate and isobornyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and the like. Hydroxyalkyl esters of (meth) acrylic acid with 2 to 8 carbon atoms; vinyl aromatic compounds such as styrene and vinyltoluene; (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, Additives of glycidyl (meth) acrylate and amines; polyethylene glycol (meth) acrylate; N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, (meth) acrylonitrile and the like. These may be used alone or in combination of two or more.

The resin having an oxazoline group used in the present invention is preferably a water-dispersible resin from the viewpoint of improving compatibility with other resins, wettability, cross-linking reaction efficiency, transparency of the coating layer, and the like. In order to make the resin having an oxazoline group a water-dispersible resin, it is preferable to contain a hydrophilic monomer as the other polymerizable unsaturated monomer.

Examples of the hydrophilic monomer include 2-hydroxyethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, a monomer having a polyethylene glycol chain such as a monoester compound of (meth) acrylic acid and polyethylene glycol, and 2-. Examples thereof include aminoethyl (meth) acrylate and salts thereof, (meth) acrylamide, N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, (meth) acrylonitrile, sodium styrene sulfonate and the like. Among these, monomers having polyethylene glycol chains such as methoxypolyethylene glycol (meth) acrylate, which is highly soluble in water, and monoester compounds of (meth) acrylic acid and polyethylene glycol (the molecular weight of the polyethylene glycol chain to be introduced is It is preferably 150 to 700, particularly 150 to 200 from the viewpoint of water resistance, and 300 to 700 from the viewpoint of compatibility with other resins and transparency of the coating layer).

In a copolymer composed of a polymerizable unsaturated monomer having an oxazoline group and another polymerizable unsaturated monomer, the composition molar ratio occupied by the polymerizable unsaturated monomer having an oxazoline group is 30 to 70 mol. %, More preferably 40-65 mol%.

The resin having an oxazoline group preferably has an oxazoline group content of 5.1 to 9.0 mmol / g. More preferably, it is in the range of 6.0 to 8.0 mmol / g. Conventionally, regarding the use of a resin having an oxazoline group for a coating layer, an example of using a resin having an oxazoline group of about 5.0 mmol / g has been reported (see, for example, Patent Document 4), but in the present invention, a relatively oxazoline group is used. Use a large amount of resin. By using a resin having a large amount of oxazoline groups, a crosslinked structure can be formed in the coating layer, and at the same time, oxazoline groups can be left in the coating layer. It can contribute to the improvement of flexibility. Such an oxazoline group-containing resin is commercially available from Nippon Shokubai Co., Ltd. as the "Epocross (registered trademark)" series.

The content ratio of the resin having an oxazoline group is preferably 20 to 60% by mass, more preferably 25 to 55% by mass, and further preferably 30 in 100% by mass of the total resin component in the resin composition for a coating layer. It is preferably up to 50% by mass. If the content of the resin having an oxazoline group is less than 20% by mass, the effect of improving the water adhesion by the oxazoline group tends not to be sufficiently exhibited, while if it exceeds 60% by mass, unreacted oxazoline groups tend to be exhibited. If the amount is too large, the cohesive force of the coating layer becomes insufficient, and the water resistance may decrease.

(Acrylic resin (B))
The resin composition for a coating layer may contain an acrylic resin in order to improve the water resistance and solvent resistance of the coating layer. As the acrylic resin, an acrylic resin containing an alkyl acrylate and / or an alkyl methacrylate (hereinafter, collectively referred to as “alkyl (meth) acrylate”) as a main component is used. Specifically, the acrylic resin usually contains an alkyl (meth) acrylate component in a content ratio of 40 to 95 mol%, and if necessary, a vinyl monomer component that is copolymerizable and has a functional group. Examples thereof include water-soluble or water-dispersible resins contained in a content ratio of 5 to 60 mol%. By setting the content ratio of the alkyl (meth) acrylate in the acrylic resin to 40 mol% or more, the coatability, the strength of the coating film, and the blocking resistance are particularly good. On the other hand, by setting the content ratio of the alkyl (meth) acrylate to 95 mol% or less and introducing a compound having a specific functional group as a copolymerization component into the acrylic resin in an amount of 5 mol% or more, water solubility or water dispersion is facilitated. As a result, the adhesiveness between the coating layer and the base film, the strength of the coating layer due to the reaction in the coating layer, water resistance, solvent resistance, etc. can be stabilized for a long period of time. Can be improved. The preferred range of the content of the alkyl (meth) acrylate is 50 to 90 mol%, more preferably 60 to 85%.

Examples of the alkyl group in the alkyl (meth) acrylate include a methyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a 2-ethylhexyl group, a lauryl group, a stearyl group, a cyclohexyl group and the like.
Examples of the functional group in the copolymerizable and functional vinyl monomer include a carboxyl group, an acid anhydride group, a sulfonic acid group or a salt thereof, an amide group or an alkylolated amide group, and an amino group ( (Including a substituted amino group), an alkylolated amino group or a salt thereof, a hydroxyl group, an epoxy group and the like, and a carboxyl group, an acid anhydride group and an epoxy group are particularly preferable. These functional groups may be only one kind or two or more kinds.

Examples of the compound having a carboxyl group or an acid anhydride group that can be used as a vinyl monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid and the like, as well as alkali metal salts and alkaline earth metals thereof. Examples thereof include salts and ammonium salts, and further include maleic anhydride and the like.
Examples of the compound having a sulfonic acid group or a salt thereof that can be used as a vinyl monomer include vinyl sulfonic acid, styrene sulfonic acid, metal salts (sodium and the like) and ammonium salts of these sulfonic acids.

Compounds having an amide group or an alkyrylated amide group that can be used as a vinyl monomer include, for example, acrylamide, methacrylamide, N-methylmethacrylamide, methylolated acrylamide, methylolated methacrylamide, and ureidovinyl ether. , Β-Ureidoisobutylvinyl ether, ureidoethylacrylate and the like.
Compounds having an amino group, an alkylolated amino group or salts thereof that can be used as a vinyl monomer include, for example, diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, 2-. Examples thereof include aminobutylvinyl ethers, dimethylaminoethylmethacrylates, dimethylaminoethylvinyl ethers, methylolized ones of these amino groups, and quaternized ones with alkyl halides, dimethyl sulfate, salton and the like.

Examples of the compound having a hydroxyl group that can be used as a vinyl monomer include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, β-hydroxyvinyl ether, and 5-. Examples thereof include hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate and the like.

Examples of the compound having an epoxy group that can be used as a vinyl monomer include glycidyl acrylate and glycidyl methacrylate.

Aqueous acrylic resins include, for example, acrylonitrile, styrenes, butyl vinyl ethers, maleic acid mono or dialkyl esters, fumaric acid mono or dialkyl, in addition to the above-mentioned functional group compounds as alkyl (meth) acrylates and vinyl monomers. Esters, itaconic acid mono or dialkyl esters, methyl vinyl ketones, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl pyridine, vinyl pyrrolidone, vinyl trimethoxysilane and the like can also be contained in combination.

The acrylic resin has a carboxyl group, and its acid value is preferably 10 mgKOH / g or less. It is more preferably 8 mgKOH / g, still more preferably 5 mgKOH / g or less. When the acid value is 10 mgKOH / g or less, the resin itself has excellent water resistance, so that the cohesive force of the coating layer can be improved without cross-linking. When the acid value exceeds 10 mgKOH / g, the strength of the coating layer is improved by crosslinking, but the flexibility of the coating layer is lowered, and the stress on the inorganic thin film layer during the retort treatment may increase.

The content ratio of the acrylic resin in the resin composition for the coating layer constituting the coating layer is 100% by mass of all the resin components in the composition (for example, the total of the resin having an oxazoline group, the acrylic resin and the urethane resin described later). It is preferably 10 to 60% by mass, more preferably 15 to 55% by mass, and even more preferably 20 to 50% by mass. If the content of the acrylic resin is less than 10% by mass, the effect of improving water resistance and solvent resistance may not be sufficiently exhibited, while if it exceeds 60% by mass, the coating layer becomes too hard and therefore moist. The stress load on the inorganic thin film layer during heat treatment tends to increase.

(Urethane resin (C))
The resin composition constituting the coating layer preferably contains a urethane resin.
As the urethane resin, for example, a water-soluble or water-dispersible resin obtained by reacting a polyhydroxy compound (polyol component) with a polyisocyanate compound according to a conventional method can be used. In particular, the aqueous polyurethane resin preferably contains a carboxyl group or a salt thereof in order to enhance the affinity with the aqueous medium. The constituent components of these urethane resins can be identified by nuclear magnetic resonance analysis or the like.

Examples of the polyhydroxy compound that is a constituent of the urethane resin include polyethylene glycol, polypropylene glycol, polyethylene / propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, and triethylene. Glycol, neopentyl glycol, polycaprolactone, polyhexamethylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, glycerin and the like can be mentioned.

Examples of the polyisocyanate compound which is a constituent of the urethane resin include toluylene diisocyanate (2,4- or 2,6-tolylene diisocyanate or a mixture thereof) (TDI) and diphenylmethane diisocyanate (4,4'-, 2, Aromatic diisocyanates such as 4'-or 2,2'-diphenylmethane diisocyanate or a mixture thereof) (MDI), aromatic aliphatic diisocyanates such as xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), 4,4- Alicyclic diisocyanates such as dicyclohexylmethane diisocyanate and 1,3-bis (isocyanatemethyl) cyclohexane, aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate (HDI) and 2,2,4-trimethylhexamethylene diisocyanate, Alternatively, polyisocyanates obtained by preliminarily adding these compounds to trimethylol propane or the like in a single or a plurality thereof can be mentioned.

In order to introduce a carboxyl group or a salt thereof into a urethane resin, for example, a polyol compound having a carboxyl group such as dimethylolpropionic acid or dimethylolbutanoic acid is used as a polyol component (polyhydroxy compound) as a copolymerization component. It may be introduced and neutralized with a salt forming agent. Specific examples of the salt forming agent include trialkylamines such as ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine and tri-n-butylamine, and N such as N-methylmorpholine and N-ethylmorpholine. -Alkylmorpholines, N-dialkylalkanolamines such as N-dimethylethanolamine, N-diethylethanolamine and the like can be mentioned. These may be used alone or in combination of two or more.

The urethane resin has a carboxyl group, and its acid value is preferably in the range of 10 to 40 mgKOH / g. As a result, the above-mentioned oxazoline group and the carboxyl group react with each other, and the coating layer can maintain flexibility while being partially crosslinked, and further improvement of cohesive force and stress relaxation of the inorganic thin film can be achieved at the same time. It is more preferably in the range of 15 to 35 mgKOH / g, and even more preferably in the range of 20 to 30 mgKOH / g.

When the coating layer contains a urethane resin, the content ratio of the urethane resin in the resin composition constituting the coating layer is the total resin component in the composition (for example, the resin having an oxazoline group, the acrylic resin and the urethane described later). The total amount of the resin) is preferably 10 to 60% by mass, more preferably 15 to 55% by mass, and even more preferably 20 to 50% by mass in 100% by mass. By containing the urethane resin in the above range, improvement in water resistance can be expected.

In the resin composition for a coating layer, the carboxyl group amount [mmol] with respect to the oxazoline group amount [mmol] in the composition is preferably 20 mmol% or less, more preferably 15 mmol% or less. be. If the amount of the carboxyl group exceeds 20 mmol%, the cross-linking reaction proceeds too much at the time of forming the coating layer, so that a large amount of oxazoline groups are consumed, and the adhesion to the inorganic thin film layer and the flexibility of the coating layer are lowered. As a result, the gas barrier property and adhesion after the wet heat treatment may be impaired.

In the present invention, the adhesion amount of the coating layer is preferably 0.010 to 0.200 g / m ² . As a result, the coating layer can be uniformly controlled, and as a result, the inorganic thin film layer can be densely deposited. In addition, the cohesive force of the coating layer itself is improved, and the adhesion between the layers of the inorganic thin film layer-coating layer-base film is increased, so that the water resistance of the coating layer can be improved. The adhesion amount of the coating layer is preferably 0.015 g / m ² or more, more preferably 0.020 g / m ² or more, still more preferably 0.025 g / m ² or more, and preferably 0.190 g / m ² or less. , More preferably 0.180 g / m ² or less, still more preferably 0.170 g / m ² or less. If the adhesion amount of the coating layer exceeds 0.200 g / m ² , the cohesive force inside the coating layer becomes insufficient and the uniformity of the coating layer also deteriorates, so that defects occur in the inorganic thin film layer, and the wet heat treatment is performed. It may not be possible to fully develop the gas barrier properties before and after. Moreover, not only the gas barrier property is lowered, but also the manufacturing cost is high, which is economically disadvantageous. On the other hand, if the film thickness of the coating layer is less than 0.010 g / m ² , sufficient gas barrier properties and interlayer adhesion may not be obtained.

The resin composition for the coating layer contains various known inorganic and organic additives such as an antistatic agent, a slip agent, and an anti-blocking agent, if necessary, as long as the present invention is not impaired. May be good.

The method for forming the coating layer is not particularly limited, and a conventionally known method such as a coating method can be adopted. Among the coating methods, the offline coating method and the inline coating method can be mentioned as preferable methods. For example, in the case of the in-line coating method performed in the process of manufacturing a base film, the conditions of drying and heat treatment at the time of coating depend on the coating thickness and the conditions of the apparatus, but immediately after coating, they are sent to the stretching process in the perpendicular direction and stretched. It is preferable to dry in the preheating zone or the stretching zone of the step, and in such a case, the temperature is usually preferably about 50 to 250 ° C.

[Inorganic thin film layer]
The laminated film of the present invention has an inorganic thin film layer on the coating layer.

The inorganic thin film layer is a thin film made of a metal or an inorganic oxide. The material for forming the inorganic thin film layer is not particularly limited as long as it can be made into a thin film, but from the viewpoint of gas barrier properties, inorganic oxidation such as silicon oxide (silica), aluminum oxide (alumina), and a mixture of silicon oxide and aluminum oxide. Things are preferred. In particular, a composite oxide of silicon oxide and aluminum oxide is preferable from the viewpoint of achieving both flexibility and denseness of the thin film layer. In this composite oxide, the mixing ratio of silicon oxide and aluminum oxide is preferably in the range of 20 to 70% for Al in terms of the mass ratio of the metal content. If the Al concentration is less than 20%, the water vapor barrier property may be lowered. On the other hand, if it exceeds 70%, the inorganic thin film layer tends to be hard, and the film may be destroyed during secondary processing such as printing or laminating, and the barrier property may be deteriorated. The silicon oxide referred to here is various silicon oxides such as SiO and SiO ₂ or a mixture thereof, and aluminum oxide is various aluminum oxides such as AlO and Al ₂ O ₃ or a mixture thereof.

The film thickness of the inorganic thin film layer is usually 1 to 100 nm, preferably 5 to 50 nm. If the film thickness of the inorganic thin film layer is less than 1 nm, it may be difficult to obtain a satisfactory gas barrier property. On the other hand, even if the thickness exceeds 100 nm, the corresponding improvement effect of the gas barrier property can be obtained. However, it is disadvantageous in terms of bending resistance and manufacturing cost.

The method for forming the inorganic thin film layer is not particularly limited, and is known, for example, a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, or an ion plating method, or a chemical vapor deposition method (CVD method). The method may be adopted as appropriate. Hereinafter, a typical method for forming an inorganic thin film layer will be described using a silicon oxide / aluminum oxide thin film as an example. For example, when the vacuum vapor deposition method is adopted, a mixture of SiO ₂ and Al ₂ O ₃ or a mixture of SiO ₂ and Al is preferably used as the vapor deposition raw material. Particles are usually used as these vapor deposition raw materials, but at that time, it is desirable that the size of each particle is such that the pressure at the time of vapor deposition does not change, and the preferable particle diameter is 1 mm to 5 mm. For heating, methods such as resistance heating, high frequency induction heating, electron beam heating, and laser heating can be adopted. Further, it is also possible to introduce oxygen, nitrogen, hydrogen, argon, carbon dioxide gas, water vapor or the like as the reaction gas, or to adopt reactive vapor deposition using means such as ozone addition and ion assist. Further, the film forming conditions can be arbitrarily changed, such as applying a bias to the material to be vapor-deposited (laminated film to be subjected to thin-film deposition) or heating or cooling the material to be vapor-deposited. Such vapor deposition material, reaction gas, bias of the vapor-film-deposited body, heating / cooling, and the like can be similarly changed when the sputtering method or the CVD method is adopted.

[Protective layer]
In the present invention, the protective layer is provided on the inorganic thin film layer. The metal oxide layer is not a completely dense film, but is dotted with minute defects. By applying a specific protective layer resin composition to be described later on the metal oxide layer to form the protective layer, the resin in the protective layer resin composition permeates the defective portion of the metal oxide layer. As a result, the effect of stabilizing the gas barrier property can be obtained. In addition, by using a material having a gas barrier property for the protective layer itself, the gas barrier performance of the laminated film is greatly improved.
In the present invention, the peak intensity (P1) having an absorption maximum in the region of 1530 ± 10 cm ^-1 and the peak intensity (P2) having an absorption maximum in the region of 1410 ± 10 cm ^-1 in the total reflection infrared absorption spectrum of the protective layer. It is necessary to contain a urethane resin having a ratio (P1 / P2) in the range of 1.5 to 3.5. It is preferably in the range of 1.7 to 3.2, and more preferably in the range of 2.0 to 3.5. The peak of 1530 ± 10 cm ^-1 is the peak of NH variable angular vibration derived from the urethane group, and is an index indicating the amount of urethane or urea bonded in the protective layer. Further, the peak of 1410 ± 10 cm ^-1 is a peak derived from the polyester base film, and is used as a reference peak when quantifying the strength. When this bond is within the above range, the cohesive force of the protective layer is improved by the sufficient hydrogen bond force between the urethane or urea bonds, and the gas barrier property is exhibited. If P1 / P2 is less than 1.5, the amount of urethane or urea group is small and it may be difficult to obtain a satisfactory gas barrier property, while if it exceeds 3.5, the gas barrier property is improved but the film is formed. Becomes brittle, which is disadvantageous in terms of bending resistance and adhesiveness.

In the present invention, the amount of the protective layer adhered is preferably 0.15 to 0.60 g / m ² . As a result, the protective layer can be uniformly controlled during coating, resulting in a film having less coating unevenness and defects. Further, the cohesive force of the protective layer itself is improved, the adhesion between the inorganic thin film layer and the protective layer is strengthened, and the water resistance can be enhanced. The amount of the protective layer adhered is preferably 0.17 g / m ² or more, more preferably 0.20 g / m ² or more, still more preferably 0.23 g / m ² or more, and preferably 0.57 g / m ² or less. , More preferably 0.54 g / m ² or less, still more preferably 0.51 g / m ² or less. When the amount of adhesion of the protective layer exceeds 0.600 g / m ² , the gas barrier property is improved, but the cohesive force inside the protective layer is insufficient, and the uniformity of the protective layer is also lowered, so that the appearance of the coat becomes uneven. Defects may occur, or the gas barrier property and adhesiveness after wet heat treatment may not be sufficiently exhibited. On the other hand, if the film thickness of the protective layer is less than 0.15 g / m ² , sufficient gas barrier properties and interlayer adhesion may not be obtained.

(Urethane resin (D))
The urethane resin (D) can be obtained by reacting the following polyisocyanate component (E) with the following polyol component (F) by a usual method. Further, the chain is extended by reacting a low molecular weight compound having two or more active hydrogens such as a diol compound (for example, 1,6-hexanediol) and a diamine compound (for example, hexamethylenediamine) as a chain extender. Is also possible.

(F) Polyisocyanate component The polyisocyanate component (F) that can be used for the synthesis of the urethane resin (D) includes aromatic polyisocyanate, alicyclic polyisocyanate, aliphatic polyisocyanate and the like. As the polyisocyanate compound, a diisocyanate compound is usually used.

Examples of the aromatic diisocyanate include tolylene diisocyanate (2,4- or 2,6-toluene diisocyanate or a mixture thereof) (TDI), phenylenedi isocyanate (m-, p-phenylenedi isocyanate or a mixture thereof), 4,4. '-Diphenylsiisocyanate, 1,5-naphthalenediocyanate (NDI), diphenylmethane diisocyanate (4,4'-, 2,4'-or 2,2'-diphenylmethane diisocyanate or a mixture thereof) (MDI) , 4,4'-toluene diisocyanate (TODI), 4,4'-diphenyl ether siisocyanate and the like can be exemplified. Examples of the aromatic aliphatic diisocyanate include xylylene diisocyanate (1,3- or 1,4-xylylene diisocyanate or a mixture thereof) (XDI) and tetramethylxylylene diisocyanate (1,3- or 1,4-tetramethyl). Examples thereof include xylylene diisocyanate or a mixture thereof) (TMXDI), ω, ω'-diisocyanate-1,4-diisocyanate and the like.

Examples of the alicyclic diisocyanate include 1,3-cyclopentenediisocyanate, cyclohexanediisocyanate (1,4-cyclohexanediisocyanate, 1,3-cyclohexanediisocyanate), and 3-isocyanatemethyl-3,5,5-trimethylcyclohexylisocyanate (iso). Holodiisocyanate, IPDI), methylenebis (cyclohexylisocyanate) (4,4'-, 2,4'-or 2,2'-methylenebis (cyclohexylisocyanate)) (hydrogenated MDI), methylcyclohexanediisocyanate (methyl-2,4- Cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate), bis (isocyanatemethyl) cyclohexane (1,3- or 1,4-bis (isocyanatemethyl) cyclohexane or a mixture thereof) (hydrogenated XDI) and the like can be mentioned.

Examples of the aliphatic diisocyanis include trimethylene diisocyanis, 1,2-propylene diisocyanate, butyrenized isocyanate (tetramethylene diisocyanate, 1,2-butyrenized isocyanate, 2,3-butyrenized isocyanate, 1,3-butyrenis diisocyanate) and hexamethylene. Diisocyanate, pendamethylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisamethylene methylcaffeite and the like can be mentioned.

(G) Glycol component As the polyol component (particularly the diol component), low molecular weight glycols to oligomers can be used, but from the viewpoint of gas barrier properties, alkylene glycols (for example, ethylene glycol, propylene glycol, trimethylene glycol) are usually used. , 1,3-Butanediol, 1,4-Butanediol, Pentandiol, Hexadiol, Neopentyl glycol, Heptanediol, Octanediol and other linear or branched C _2-10 alkylene glycols), (Poly) Low molecular weight glycols such as Oxy-C _2-4 alkylene glycol (diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, etc.) are used. Preferred glycol components are C _2-8 polyol components [eg, C _2-6 alkylene glycols (particularly ethylene glycol, 1,2- or 1,3-propylene glycol, 1,4-butanediol, 1,6-hexane). Diol, 3-methyl-1,5-pentanediol), etc.], di or trioxy C _2-3 alkylene glycol (diethylene glycol, triethylene glycol, dipropylene glycol, etc.), and a particularly preferable diol component is C _2-8 alkylene. Glycol (particularly C _2-6 alkylene glycol).

These diol components can be used alone or in combination of two or more. Further, if necessary, aromatic diols (eg, bisphenol A, bishydroxyethyl terephthalate, catechol, resorcin, hydroquinone, 1,3- or 1,4-xylylene diol or a mixture thereof, etc.), alicyclic diols (eg, bisphenol A, bishydroxyethyl terephthalate, catechol, resorcin, hydroquinone, etc.), alicyclic diols ( For example, a low molecular weight diol component such as hydrogenated bisphenol A, xylylene diol, cyclohexanediol, cyclohexanedimethanol, etc. may be used in combination. Further, if necessary, a trifunctional or higher functional polyol component, for example, a polyol component such as glycerin, trimethylolethane, or trimethylolpropane can be used in combination. The polyol component preferably contains at least a C _2-8 polyol component (particularly, C _2-6 alkylene glycol). The ratio of the C _2-8 polyol component (particularly, C _2-6 alkylene glycol) in 100% by mass of the polyol component can be selected from the range of about 50 to 100% by mass, and usually 70% by mass or more and 100% by mass or less. It is preferable, more preferably 80% by mass or more and 100% by mass or less, and further preferably 90% by mass or more and 100% by mass or less.

In the present invention, it is more preferable to use a urethane resin containing an aromatic or aromatic aliphatic diisocyanate component as a main component from the viewpoint of improving the gas barrier property. Among them, it is particularly preferable to contain a metaxylylene diisocyanate component. By using the above resin, the cohesive force of the urethane bond can be further enhanced by the stacking effect between the aromatic rings, and as a result, a good gas barrier property can be obtained. In addition, the polar group of the urethane bond interacts with the inorganic thin film layer, and the urethane resin also has flexibility due to the presence of the amorphous portion, so that damage to the inorganic thin film layer is suppressed even when a bending load is applied. Can be done.

In the present invention, the proportion of aromatic or aromatic aliphatic diisocyanate in the urethane resin is preferably in the range of 50 mol% or more (50 to 100 mol%) in 100 mol% of the polyisocyanate component (F). The ratio of the total amount of the aromatic or aromatic aliphatic diisocyanate is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, still more preferably 80 to 100 mol%. As such a resin, the "Takelac (registered trademark) WPB" series commercially available from Mitsui Chemicals, Inc. can be suitably used. If the proportion of the total amount of aromatic or aromatic aliphatic diisocyanates is less than 50 mol%, good gas barrier properties may not be obtained.

The urethane resin preferably has a carboxylic acid group (carboxyl group) from the viewpoint of improving the affinity with the inorganic thin film layer. In order to introduce a carboxylic acid (salt) group into the urethane resin, for example, a polyol compound having a carboxylic acid group such as dimethylolpropionic acid and dimethylolbutanoic acid may be introduced as a copolymerization component as a polyol component. Further, if the carboxylic acid group-containing urethane resin is synthesized and then neutralized with a salt-forming agent, an aqueous dispersion urethane resin can be obtained. Specific examples of the salt forming agent include trialkylamines such as ammonia, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine and tri-n-butylamine, and N such as N-methylmorpholine and N-ethylmorpholine. -Examples include N-dialkylalkanolamines such as alkylmorpholines, N-dimethylethanolamine and N-diethylethanolamine. These may be used alone or in combination of two or more.

(Characteristics of urethane resin)
The acid value of the urethane resin is preferably in the range of 10 to 60 mgKOH / g. It is more preferably in the range of 15 to 55 mgKOH / g, and even more preferably in the range of 20 to 50 mgKOH / g. When the acid value of the urethane resin is within the above range, the liquid stability is improved when it is made into an aqueous dispersion, and the protective layer can be uniformly deposited on the highly polar inorganic thin film, so that the coat appearance is good. Will be.

The urethane resin of the present invention preferably has a glass transition temperature (Tg) of 80 ° C. or higher, more preferably 90 ° C. or higher. By setting the Tg to 80 ° C. or higher, the swelling of the protective layer due to molecular motion in the wet heat treatment process (heating to heat retention to temperature lowering) can be reduced.

The laminated film of the present invention has an oxygen permeability of 5 ml / m ² · d · MPa or less under the condition of 23 ° C. × 65% RH, and exhibits good gas barrier properties. Further, by controlling the above-mentioned protective layer component / adhesion amount, it can be preferably 4 ml / m ² · d · MPa or less, more preferably 3 ml / m ² · d · MPa or less. When the oxygen permeability is 5 ml / m ² · d · MPa or more, it becomes difficult to cope with applications requiring high gas barrier properties.

From the above, the laminated film of the present invention is a gas barrier laminated film (laminated body) having excellent oxygen barrier properties after wet heat treatment, high interlayer adhesion, and appropriate bending resistance.

[Other layers]
In addition to the above-mentioned base film, coating layer, inorganic thin film layer, and protective layer, the gas barrier laminated film provided with the inorganic thin film layer using the laminated film of the present invention includes a known gas barrier laminated film, if necessary. Various layers provided by the film can be provided.
For example, when a gas barrier laminated film provided with an inorganic thin thin film layer is used as a packaging material, it is preferable to form a heat-sealing resin layer called a sealant. The heat-sealing resin layer is usually provided on the inorganic thin film layer, but may be provided on the outside of the base film (the surface opposite to the coating layer forming surface). The heat-sealing resin layer is usually formed by an extrusion laminating method or a dry laminating method. The thermoplastic polymer that forms the heat-sealable resin layer may be any as long as it can sufficiently exhibit sealant adhesiveness, and polyethylene resins such as HDPE, LDPE, and LLDPE, and polypropylene resins. Ethylene-vinyl acetate copolymer, ethylene-α-olefin random copolymer, ionomer resin and the like can be used.

Further, the gas barrier laminated film provided with the inorganic thin thin film layer includes a printed layer or other plastic base material and / or a paper base between or outside the inorganic thin film layer or the base film and the heat-sealing resin layer. At least one layer or more of the material may be laminated.

As the printing ink forming the printing layer, water-based and solvent-based resin-containing printing inks can be preferably used. Examples of the resin used for the printing ink include an acrylic resin, a urethane resin, a polyester resin, a vinyl chloride resin, a vinyl acetate copolymer resin, and a mixture thereof. Known printing inks include antistatic agents, light blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoaming agents, cross-linking agents, blocking agents, antioxidants and the like. Additives may be included. The printing method for providing the print layer is not particularly limited, and known printing methods such as an offset printing method, a gravure printing method, and a screen printing method can be used. For drying the solvent after printing, known drying methods such as hot air drying, hot roll drying, and infrared drying can be used.

On the other hand, as the other plastic base material or paper base material, paper, polyester resin, polyamide resin, biodegradable resin and the like are preferably used from the viewpoint of obtaining sufficient rigidity and strength of the laminated body. Further, in order to obtain a film having excellent mechanical strength, a stretched film such as a biaxially stretched polyester film and a biaxially stretched nylon film is preferable.

In particular, when a gas barrier laminated film provided with an inorganic thin film layer is used as a packaging material, nylon is used to improve mechanical properties such as pinhole property and piercing strength between the inorganic thin film layer and the heat-sealing resin layer. It is preferable to stack the films. Here, as the type of nylon, nylon 6, nylon 66, metaxylene adipamide and the like are usually used. The thickness of the nylon film is usually 10 to 30 μm, preferably 15 to 25 μm. If the nylon film is thinner than 10 μm, the strength may be insufficient, while if it exceeds 30 μm, the nylon film may be too stiff and unsuitable for processing. As the nylon film, a biaxially stretched film having a stretching ratio in each of the vertical and horizontal directions of usually 2 times or more, preferably about 2.5 to 4 times is preferable.

The laminated film of the present invention also includes an embodiment having each of the above-mentioned layers other than the coating layer and the inorganic thin film layer.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples, and is appropriately modified and carried out to the extent that it can meet the purposes of the preceding and the following. It is also possible, all of which are within the technical scope of the invention. Unless otherwise specified, "%" means "% by mass" and "part" means "part by mass".

The evaluation method and the physical property measurement method used in each Example and Comparative Example are as follows.

(1) Preparation of Laminate Laminate for Evaluation On the inorganic thin film layer of each laminated film obtained in Examples and Comparative Examples, a urethane-based two-component curable adhesive (Takelac (registered trademark) A525S manufactured by Mitsui Kagaku Co., Ltd.) And "Takenate (registered trademark) A50" in a ratio of 13.5: 1 (mass ratio)) as a heat-sealable resin layer, a 70 μm-thick unstretched polypropylene film (P1147 manufactured by Toyobo Co., Ltd.). ") Are laminated by a dry laminating method and aged at 40 ° C. for 4 days to obtain a laminated gas barrier laminate for evaluation (hereinafter, also referred to as" laminated laminate "). The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was about 4 μm.

(2) Oxygen permeability evaluation method For the obtained laminated film alone, an oxygen permeability measuring device (MOCON's "OX-TRAN") according to the electrolytic sensor method of JIS-K7126-2 (Appendix A). 2/20 ”) was used to measure the oxygen permeability under normal conditions in an atmosphere of a temperature of 23 ° C. and a relative humidity of 65%. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side on which the coating layer / protective layer is not laminated to the coating layer / protective layer side.

On the other hand, the laminated laminate prepared in (1) above was subjected to a wet heat treatment for holding it in hot water at 130 ° C. for 30 minutes, dried at 40 ° C. for 1 day (24 hours), and after the obtained wet heat treatment. Oxygen permeability (after retort) was measured in the same manner as above for the laminated laminate of.

(3) Evaluation method of laminate strength The laminated laminate prepared in (1) above is subjected to a wet heat treatment for 30 minutes in hot water at 130 ° C., and is 15 mm wide and 15 mm long in an undried state. Cut out to 200 mm and use as a test piece, and under the conditions of temperature 23 ° C and relative humidity 65%, use a Tencilon universal material tester (“Tencilon UMT-II-500 type” manufactured by Toyo Baldwin) to make a laminate strength (retort). Later) was measured. The laminating strength was defined as the strength when the tensile speed was 200 mm / min, water was applied between the laminated film and the heat-sealing resin layer, and the film was peeled off at a peeling angle of 90 degrees.

(4) Evaluation method of bending barrier resistance The laminated laminate prepared in (1) above was used as a sample piece of 112 inches × 8 inches, and a gelboflex tester (MIL-B131H manufactured by Rigaku Kogyo Co., Ltd.) was used with a diameter of 3 (1). / 2) Inch is mounted in a cylindrical shape, both ends are held, the initial grip interval is 7 inches, and a twist of 400 degrees is added at 3 (1/2) inches of stroke, and the reciprocating motion of this operation is 50. The test was performed 50 times at a rate of times / min under the conditions of 23 ° C. and a relative humidity of 65%. The oxygen permeability (after the bending treatment) of the obtained laminated laminate after the bending test was measured in the same manner as above.

(5) Method for Measuring Total Internal Reflection Infrared Absorption Spectrum of Protective Layer In each Example and Comparative Example, the surface of the coating layer of each laminated film obtained is subjected to total internal reflection infrared absorption by total internal reflection absorption infrared spectroscopy. The spectrum was measured to determine the peak intensity (P1) having an absorption maximum in the region of 1530 ± 10 cm ^-1 and the peak intensity (P2) having an absorption maximum in the region of 1410 ± 10 cm ^-1 , and the intensity ratio (P1 / P2). ) Was calculated. The calculation of each peak intensity was performed from the baseline of zero absorbance and the peak height connecting each peak top vertically.

(Measurement condition)
Equipment: "ALPHA ECO-ATR" manufactured by Bruker Optics Co., Ltd.
Optical crystal: Ge
Incident angle: 45 °
Resolution: 8 cm ^-1
Accumulation number: 64 times

(5) Method for Measuring Adhesion Amount of Protective Layer In each Example and Comparative Example, each laminated film obtained at the stage of laminating the protective layer on the base film was used as a sample, and a 100 mm × 100 mm test piece was used from this sample. After cutting out, the protective layer was wiped with 1-methoxy-2-propanol or dimethylformamide, and the amount of adhesion was calculated from the change in the mass of the film before and after wiping.

(6) Amount of oxazoline group in resin having oxazoline group The resin containing oxazoline is freeze-dried, and ¹ H-NMR spectrum is measured using a nuclear magnetic resonance spectrometer (NMR) Gemini-200 manufactured by Varian, and the oxazoline group is measured. The absorption peak intensity derived from the above and the absorption peak intensity derived from other monomers were determined, and the oxazoline group amount (mmol / g) was calculated from those peak intensities.

(7) Method for Quantifying Isocyanate Component in Urethane Resin The sample is dried under reduced pressure, ¹ H-NMR spectrum is measured using a nuclear magnetic resonance spectrometer (NMR) Gemini-200 manufactured by Varian, and it is derived from each isocyanate component. The molar% ratio of the isocyanate component was determined from the integrated ratio of the peak intensities.

Each material used for forming the covering layer and the protective layer in each Example and Comparative Example was prepared as follows.

<Preparation of each material used for forming the coating layer or protective layer>
[Resin (A) having an oxazoline group]
As a resin having an oxazoline group, a commercially available water-soluble oxazoline group-containing acrylate (“Epocross (registered trademark) WS-300” manufactured by Nippon Shokubai Co., Ltd .; solid content 10%) was prepared. The amount of oxazoline groups in this resin was 7.7 mmol / g.

[Acrylic resin (B)]
As an acrylic resin, a 25% by mass emulsion of a commercially available acrylic acid ester copolymer (“Mobile (registered trademark) 7980” manufactured by Nichigo Mobile Co., Ltd.” was prepared. The acid value (theoretical value) of this acrylic resin (B). ) Was 4 mgKOH / g.

[Urethane resin (C)]
As the urethane resin, a commercially available polyester urethane resin dispersion (“Takelac (registered trademark) W605” manufactured by Mitsui Chemicals, Inc .; solid content 30%) was prepared. The acid value of this urethane resin was 25 mgKOH / g, and the glass transition temperature (Tg) measured by DSC was 100 ° C. .. The ratio of aromatic or aromatic aliphatic diisocyanate to the total polyisocyanate component measured by ¹ H-NMR was 55 mol%.
[Urethane resin (D)]
As the urethane resin, a commercially available dispersion of a urethane resin containing a metaxylylene group (“Takelac (registered trademark) WPB341” manufactured by Mitsui Chemicals, Inc .; solid content 30%) was prepared. The acid value of this urethane resin was 25 mgKOH / g, and the glass transition temperature (Tg) measured by DSC was 130 ° C. The ratio of aromatic or aromatic aliphatic diisocyanate to the total polyisocyanate component measured by ¹ H-NMR was 85 mol%.
[Gas barrier vinyl alcohol resin (E)]
As a vinyl alcohol-based resin having gas barrier properties, a commercially available water-soluble vinyl alcohol resin (“Nichigo G-Polymer (registered trademark) OKS-8049”; powder) manufactured by Nippon Synthetic Chemical Co., Ltd. is dissolved in water and has a solid content of 5%. An aqueous solution was prepared.

Example 1
(1) Adjustment of Coating Liquid 1 Used for Coating Layer Each material was mixed at the following blending ratio to prepare a coating liquid (resin composition for coating layer). The mass ratios of the resin (A), the acrylic resin (B), and the urethane resin (C) having an oxazoline group in the obtained coating liquid in terms of solid content are as shown in Table 1.
Water 54.40%
Isopropanol 25.00%
Oxazoline group-containing resin (A) 15.00%
Acrylic resin (B) 3.60%
Urethane resin (C) 2.00%

(2) Preparation of coating liquid 2 used for coating the protective layer The following coating agents were mixed to prepare a coating liquid 2. Here, the mass ratio of the urethane resin (D) in terms of solid content is as shown in Table 1.
Water 60.00%
Isopropanol 30.00%
Urethane resin (D) 10.00%

(3) Production of polyester base film and coating of coating liquid 1 (lamination of coating layer)
A polyethylene terephthalate resin having an ultimate viscosity of 0.62 dl / g (30 ° C., phenol / tetrachloroethane = 60/40) is pre-crystallized, then dried, and extruded at 280 ° C. using an extruder equipped with a T-die to have a surface temperature. It was rapidly cooled and solidified on a drum at 40 ° C. to obtain an amorphous sheet. Next, the obtained sheet was stretched 4.0 times at 100 ° C. in the longitudinal direction between the heating roll and the cooling roll. Then, the coating liquid 1 was coated on one side of the obtained uniaxially stretched film by the fountain bar coating method. Guided to a tenter while drying, preheated at 100 ° C, stretched 4.0 times laterally at 120 ° C, heat treated at 225 ° C with 6% lateral relaxation, biaxially stretched polyester with a thickness of 12 μm. A laminated film having a 0.020 g / m2 coating layer formed on the film was obtained.

(4) Formation of inorganic thin film layer (deposited film)
Next, a composite inorganic oxide layer of silicon dioxide and aluminum oxide was formed as an inorganic thin film layer on the coating layer surface of the laminated film obtained in (2) above by an electron beam vapor deposition method. As the vapor deposition source, particulate SiO ₂ (purity 99.9%) and A1 ₂ O ₃ (purity 99.9%) having a purity of about 3 mm to 5 mm were used. Here, the composition of the composite oxide layer was SiO ₂ / A1 ₂ O ₃ (mass ratio) = 60/40. The film thickness of the inorganic thin film layer (SiO ₂ / A1 ₂ O ₃ composite oxide layer) was 13 nm.
(5) Coating of coating liquid 2 on thin-film vapor deposition film (lamination of protective layer)
The coating liquid 2 was applied onto the inorganic thin film layer of the vapor-filmed film obtained in (4) by the wire bar coating method, and dried at 200 ° C. for 15 seconds to obtain a protective layer. The coating amount after drying was 0.190 g / m2 (Dry).
As described above, a laminated film having a coating layer / metal oxide layer / protective layer on the base film was produced. As described above, the oxygen permeability and the laminating strength of the obtained laminated film were evaluated. The results are shown in Table 2.

(Examples 2 to 4, Comparative Examples 1 to 6)
In preparing the coating liquid for forming the coating layer, each material has a mass ratio in terms of solid content of the oxazoline group-containing resin (A), the acrylic resin (B) and the urethane resin (C) as shown in Table 1. (At this time, the ratio of isopropanol to the total amount of the coating liquid was 25.00% by mass as in Example 1), or when preparing the coating liquid for forming the protective layer, the resin was used. Examples except that the amount and type of adhesion were changed to be as shown in Table 1 (at this time, the ratio of isopropanol to the total amount of the coating liquid was 30.00% by mass as in Example 1). A laminated film was prepared in the same manner as in No. 1, and the oxygen permeability and the laminated strength were evaluated. The results are shown in Table 2.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a gas barrier laminated film having an inorganic thin film layer, which is excellent in gas barrier property and adhesiveness at the same time even after being subjected to a wet heat treatment as well as in a normal state. The gas barrier laminated film has the advantages of being easy to manufacture, excellent in economy and production stability, and easy to obtain uniform characteristics. Therefore, the gas barrier laminated film is used for food packaging for wet heat treatment. In addition to packaging applications for various foods, pharmaceuticals, industrial products, etc., it can also be widely used for industrial applications such as solar cells, electronic papers, organic EL elements, and semiconductor elements.

Claims (2)

The coating layer has a coating layer on one side of the polyester base film, and the coating layer comprises a resin composition for a coating layer containing a resin having an oxazoline group as a constituent component. A protective layer made of urethane resin having an adhesion amount of 0.15 to 0.60 g / m ² is provided on the inorganic thin film layer, and the total reflection infrared absorption spectrum on the protective layer surface side of the laminated film is 1530 ± 10 cm ^-1 . The ratio (P1 / P2) of the peak intensity (P1) having the absorption maximum in the region of 1410 ± 10 cm ^-1 and the peak intensity (P2) having the absorption maximum in the region of 1410 ± 10 cm -1 is in the range of 1.5 to 3.5. In addition, the heat-sealable resin layer is laminated on the laminated film characterized in that the oxygen permeability of the laminated film under the condition of 23 ° C. × 65% RH is 5 ml / m ² · d · MPa or less. body. The laminate according to claim 1, wherein the laminate is used as a packaging material.