JP7359235B2 - laminate laminate - Google Patents

Description

The present invention relates to a laminate used in the field of packaging foods, pharmaceuticals, industrial products, etc. Specifically, the present invention relates to a laminate that can improve the interlayer adhesion of the inorganic thin film layers and exhibit good gas barrier properties and adhesion when formed into a gas barrier laminate including an inorganic thin film layer.

Packaging materials used for foods, pharmaceuticals, etc. must have gas barrier properties, which block gases such as oxygen and water vapor, in order to suppress the oxidation of proteins and oils, preserve taste and freshness, and maintain the efficacy of pharmaceuticals. It has been demanded. Furthermore, gas barrier materials used in electronic devices and electronic components such as solar cells and organic EL require higher gas barrier properties than packaging materials for foods and the like.

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 coated with a thin metal film made of aluminum or an inorganic oxide such as silicon oxide or aluminum oxide. Gas barrier laminates formed with inorganic thin films are commonly used. Among these, those formed with a thin film (inorganic thin film layer) of an inorganic oxide such as silicon oxide, aluminum oxide, or a mixture thereof are widely used because they are transparent and the contents can be confirmed. Furthermore, since inorganic thin film layers made of inorganic oxides can be heated in a microwave oven, demand is increasing, especially for microwaveable retort pouches.

Microwavable retort pouches require water resistance, heat resistance, and toughness (breakage resistance and pinhole resistance) at the same time. It is common to have a structure of at least three layers in which heat-sealable resin is dry-laminated on the contents side) via an adhesive.

In the above-mentioned retort pouch structure, the gas barrier layer is generally laminated on the polyester film located on the outside of the bag from the viewpoint of productivity and quality stability, and its barrier performance is also very good. (For example, Patent Document 1). However, when a polyamide film and a heat-sealable resin are bonded together to form a three-layer structure, at least two or more adhesive layers and, in some cases, a printed layer are present inside the gas barrier layer, and polyester Since a barrier layer with excellent gas barrier properties is present on the film side, there has been a problem in that residual solvent in the adhesive or ink tends to migrate in one direction to the content side.

On the other hand, there is a conventional technique in which a gas barrier layer is laminated on a polyamide film as an intermediate layer (for example, Patent Document 2), but a gas barrier laminated film based on a polyamide film has weak moisture and heat resistant adhesive properties due to the characteristics of the polyamide film. Physical damage to the barrier layer due to expansion/contraction and wrinkles due to moisture absorption of the sheath and base material may result in insufficient barrier properties compared to when laminated on a polyester film. In addition, polyamide films are inferior to polyester films in terms of heat resistance, and there are also problems in processing, such as the tendency for heat shrinkage wrinkles to form during coating and drying. As described above, there is currently no gas barrier film that has excellent production stability and economic efficiency during manufacturing, and that maintains excellent barrier properties and adhesive properties even when subjected to severe moist heat treatment such as retort processing. Met.

International publication WO2016/136768 Patent No. 4857482

Although the above-mentioned Patent Document 1 examines the retort barrier performance, it does not consider the optimal film configuration or concerns about migration of residual solvent to the contents. Further, in Patent Document 2, retort barrier resistance was also studied, but moisture and heat resistant adhesiveness was not studied. Furthermore, the transferability of residual solvent to the contents was not considered.

The present invention was made against the background of such problems in the prior art, and when a laminate including a gas-barrier laminated polyamide film with an inorganic thin film layer is made, it is subjected to severe moist heat treatment such as normal and retort treatment. The objective of the present invention is to provide a laminate that has excellent gas barrier properties and adhesion between layers even after drying, has little residual solvent migration to the contents, is easy to manufacture, and is economical.

The gas barrier laminate of the present invention that solves the above problems has the following aspects.

(1) A laminate laminate in which a polyester film, a polyamide base film, and a heat-sealable resin are laminated, wherein at least one side of the polyamide base film has a coating layer, an inorganic thin film layer, and a protective layer. A laminated film formed by laminating in this order with or without intervening layers, characterized in that the covering layer contains a polyester resin, and the protective layer contains a urethane resin containing metaxylylene groups. laminate laminate.

(2) The laminate according to (1) above, wherein the protective layer contains at least one of a silicon-based crosslinking agent and a carbodiimide.

(3) The laminate according to any one of (1) or (2) above, wherein the polyester resin contained in the coating layer is an acrylic graft polyester resin.

(4) The laminate according to any one of (1) to (3) above, wherein the inorganic thin film layer is a layer made of a composite oxide of silicon oxide and aluminum oxide.

According to the present invention, when a gas barrier laminate comprising a coating layer, an inorganic thin film layer, and a protective layer is formed, it has excellent water-resistant adhesion, and therefore does not peel off even when subjected to severe moist heat treatment such as retort treatment. There is no problem of deterioration of barrier properties or leakage of contents. In addition, a barrier layer is provided as an intermediate layer that has gas permeability that is more appropriate than that of aluminum foil, so that residual solvent is less likely to transfer to the contents. Moreover, since the laminated film of the present invention can be manufactured easily with fewer processing steps, it is excellent in both economical efficiency and production stability, and can provide a gas barrier film with uniform characteristics.

The laminate of the present invention has a structure of at least three layers, in which a polyamide base laminated film is used as an intermediate layer, a polyester film is laminated on one side, and a heat-sealable resin layer is laminated on the other side. Further, a coating layer, an inorganic thin film layer, and a protective layer are provided on at least one side of the polyamide base film. This laminated film is referred to as a polyamide base laminated film. Hereinafter, the base film and each layer laminated thereon will be explained in order.

[Polyester film]
The polyester film used in the present invention is, for example, a film obtained by melt-extruding plastic polyester and subjecting it to stretching, cooling, and heat setting in the longitudinal direction and/or width direction (uniaxially stretched film or biaxially stretched film). ) can be used. Examples of the plastic polyester include polyesters represented by polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, and polylactic acid. Among these, polyethylene terephthalate or a copolymer obtained by copolymerizing polyethylene terephthalate with other components is preferred in terms of heat resistance, dimensional stability, and transparency, and biaxially oriented polyethylene terephthalate is particularly preferred.

As the polyester film, any film thickness can be used depending on the desired purpose and use such as mechanical strength and transparency, and the film thickness is not particularly limited, but it is usually 5 to 250 μm. The recommended thickness is 10 to 60 μm when used as a packaging material.
The transparency of the polyester film is not particularly limited, but when used as a packaging material that requires transparency, it is desirable to have a light transmittance of 50% or more.

The polyester film may be a single-layer film made of one type of polyester, or a laminated film made of two or more types of polyester films laminated. In the case of forming a laminate film, the type of laminate, the number of layers, the method of lamination, etc. are not particularly limited, and can be arbitrarily selected from known methods depending on the purpose.
In addition, the polyester film may be subjected to surface treatments such as corona discharge treatment, glow discharge treatment, flame treatment, surface roughening treatment, etc., as long as the object of the present invention is not impaired. , printing, decoration, etc. may be applied.

[Polyamide base film]
In the present invention, a polyamide film typified by nylon 4/6, nylon 6, nylon 6/6, nylon 12, etc. is used as the base material of the gas barrier layer (hereinafter sometimes referred to as base film). Polyamide base films are superior to other resin base films in terms of bag tear resistance and pinhole resistance. As the polyamide resin used for the polyamide base film in the present invention, for example, nylon 6 whose main raw material is ε-caprolactam can be mentioned. Examples of other polyamide resins include polyamide resins obtained by polycondensation of lactams with three or more membered rings, ω-amino acids, dibasic acids, and diamines. Specifically, in addition to the above-mentioned ε-caprolactam, lactams include enantlactam, capryllactam, and lauryllactam, and ω-amino acids include 6-aminocaproic acid, 7-aminoheptanoic acid, and 9-aminoheptanoic acid. Examples include aminononanoic acid and 1,1-aminoundecanoic acid. In addition, dibasic acids include adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadionic acid, hexadecadionic acid, eicosandioic acid, eicosadienedionic acid, , 2,4-trimethyladipic acid, terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, and xylylene dicarboxylic acid. Furthermore, as diamines, ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, pentamethylenediamine, undecamethylenediamine, 2,2,4 (or 2,4,4)-trimethylhexamethylenediamine, cyclohexane Examples include diamine, bis-(4,4'-aminocyclohexyl)methane, and metaxylylene diamine. Polymers obtained by polycondensing these or copolymers thereof, such as nylon 6, 7, 11, 12, 6.6, 6.9, 6.11, 6.12, 6T, 6I, MXD6 (metaxylene dipanamide 6), 6/6.6, 6/12, 6/6 T, 6/6I, 6/MXD6, etc. can be used. In addition, when manufacturing the polyamide resin laminated film roll before vapor deposition of the present invention, the above-mentioned polyamide resins can be used alone or in combination of two or more.

As the base film, any film thickness can be used depending on the desired purpose and application such as mechanical strength and transparency, and the film thickness is not particularly limited, but it is usually 5 to 100 μm. is recommended, and when used as a packaging material, it is preferably 8 to 60 μm. The transparency of the base film is not particularly limited, but when used as a packaging material requiring transparency, it is desirable to have a light transmittance of 50% or more.

From the viewpoint of imparting mechanical strength, the polyamide base film is preferably a stretched film stretched in at least one direction, the longitudinal direction or the transverse direction, and a biaxially stretched film stretched in two directions, the longitudinal direction and the transverse direction. More preferably, it is a stretched film. Any stretching method such as simultaneous biaxial stretching or sequential biaxial stretching can be used as the stretching method for the biaxially stretched film. As a preferred embodiment of the stretching method in sequential biaxial stretching, an unstretched film is stretched in the longitudinal direction at a stretching ratio of 3.0 to 4.5 times using a roll-type stretching machine at a temperature of 70° C. to 90° C. The method includes stretching, then stretching with a tenter-type stretching machine at a temperature of 110°C to 140°C at a stretching ratio of 3.5 to 5.5 times, and then heat-treating at a temperature of 180°C to 230°C after stretching. be able to. In addition, when an in-line coating method is adopted as the step of forming the coating layer described below, the coating layer is coated on the stretched film in the longitudinal direction in the step of the sequential biaxial stretching described above, and then continuously The film can be introduced into a tenter-type stretching machine to be subjected to transverse stretching and heat treatment.

The base film may be a single-layer film made of polyamide resin, or a laminated film in which a polyamide resin layer and other plastic films (two or more types may be used) are laminated. . The type of laminate in the case of forming a laminate film is not particularly limited in terms of the number of layers, the method of lamination, etc., and can be arbitrarily selected from known methods depending on the purpose, as long as there is a polyamide resin layer.

Further, in the present invention, in order to improve the interlayer adhesion between the inorganic thin film layer and the polyamide base material, a desired surface treatment layer can be provided in advance, if necessary.
In the present invention, the above-mentioned surface treatment layer includes, for example, corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, etc. For example, a corona treatment layer, an ozone treatment layer, a plasma treatment layer, an oxidation treatment layer, and the like can be formed by optionally performing pretreatments such as the following. The above surface pretreatment is carried out as a method to improve the close adhesion between various resin films and metal oxide vapor deposited films. For example, a primer coating agent layer, an undercoating agent layer, an anchor coating agent layer, an adhesive layer, a vapor-deposited anchor coating agent layer, etc. are optionally formed on the surface of various resin films in advance, and then the coating is performed. It can also be a layer.

[Coating layer of polyamide base laminated film]
In order to improve the adhesion strength between the base material layer and the inorganic thin film layer by forming the coating layer, it is preferable to use polyester resin from the viewpoint of cost and hygiene. The copolymerized polyester resin used in the present invention is essentially a water-insoluble resin that does not disperse or dissolve in water by itself, preferably has a molecular weight of 5,000 to 50,000, and has a preferable polymer composition in which all acid components are 60 to 99.5 mol% of aromatic dicarboxylic acid, 0 to 40 mol% of aliphatic dicarboxylic acid and/or alicyclic dicarboxylic acid, and 0.5 to 10 mol% of dicarboxylic acid containing a polymerizable unsaturated double bond. It is mole%. Further, it is preferable to use an acrylic graft polyester resin obtained by graft copolymerizing an acrylic monomer as the polyester resin, since the film can be cured and the cohesive force can be improved. This will be explained in detail below.

Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, biphenyldicarboxylic acid, and a small amount of 5-sodium sulfoisophthalic acid may be used as long as it does not impair water resistance. be able to. Examples of aliphatic dicarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimer acid, and examples of alicyclic dicarboxylic acids include 1,4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and its acid anhydride, etc. are used. The content of the aliphatic dicarboxylic acid and/or alicyclic dicarboxylic acid is more preferably 70 to 98 mol%, and more preferably 0 to 30 mol%. When the aromatic dicarboxylic acid content is less than 60 mol %, the processability of the coating film tends to decrease.

Examples of dicarboxylic acids containing polymerizable unsaturated double bonds include fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, and alicyclic acids containing unsaturated double bonds as α,β-unsaturated dicarboxylic acids. Examples of the group dicarboxylic acids include 2,5-norbornenedicarboxylic anhydride and tetrahydrophthalic anhydride. Among these, the most preferred are fumaric acid, maleic acid and 2,5-norbornenedicarboxylic acid (endo-bicyclo-(2,2,1)-5-heptene-2,3-dicarboxylic acid). The amount of dicarboxylic acid containing a polymerizable unsaturated double bond is 2 to 7 mol % based on the total acid components. If the amount of dicarboxylic acid containing a polymerizable unsaturated double bond is 2 mol% or less, efficient grafting of the radically polymerizable monomer to the polyester resin is difficult, and the dispersed particle size in the aqueous medium becomes large. There is a tendency that dispersion stability tends to decrease. If the amount of the dicarboxylic acid containing a polymerizable unsaturated double bond exceeds 7 mol %, the viscosity increases too much in the latter stage of the grafting reaction, which is undesirable because it hinders the uniform progress of the reaction.

0 to 5 mol% of trifunctional or more functional polycarboxylic acid and/or polyol can be copolymerized into the copolymerized polyester resin used in the present invention, but as the trifunctional or more functional polycarboxylic acid ( (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) benzophenonetetracarboxylic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), etc. are used. On the other hand, as trifunctional or higher functional polyols, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc. are used. Trifunctional or higher functional polycarboxylic acids and/or polyols are copolymerized in an amount of 0 to 5 mol% based on the total acid component or total glycol component, and 0 to 3 mol% considering processability. is preferred.

The radically polymerizable monomers to be graft-polymerized to the copolymerized polyester resin include radically polymerizable monomers that have a hydrophilic group or have a group that can be later converted into a hydrophilic group, and other radically polymerizable monomers. It is a sexual monomer. Examples of hydrophilic groups include carboxyl groups, hydroxyl groups, phosphoric acid groups, phosphorous acid groups, sulfonic acid groups, amide groups, quaternary ammonium salts, etc. Groups that can be converted into hydrophilic groups include can include an acid anhydride group, a glycidyl group, a chloro group, etc. Among these hydrophilic groups, a carboxyl group is preferred because water dispersibility can be easily controlled by changing the acid value, and radically polymerizable monomers having a carboxyl group or a group that generates a carboxyl group are preferred.

In addition to acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, etc., carboxyl group-containing radically polymerizable monomers that can be graft-polymerized to copolyester resin and change the acid value include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, etc. Examples include maleic anhydride, itaconic anhydride, and methacrylic anhydride, which easily generate carboxylic acid when in contact with an aqueous alkaline medium, and one or more of these can be selected and used. The most preferred carboxyl group-containing radically polymerizable monomers are acrylic acid, methacrylic acid and maleic anhydride.

In the copolymerized polyester resin aqueous dispersion used in the present invention, in addition to these carboxyl group-containing radically polymerizable monomers, a radically polymerizable monomer that does not contain a carboxyl group is usually used in combination. A wide range of radically polymerizable monomers can be mentioned as these radically polymerizable monomers that do not contain a carboxyl group. That is, esters of acrylic acid and methacrylic acid include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, Methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxylpropyl methacrylate, etc. Well-known monomers include acrylonitrile, methacrylonitrile, acrylamide, N-methylolacrylamide, diacetone acrylamide, vinyl acetate, vinyl ethers, N-vinylpyrrolidone, styrene, α-methylstyrene, and t-butylstyrene. , vinyltoluene, etc., and one or more types can be selected and used from these.

The copolymerized polyester resin-based graft polymer can be efficiently obtained by graft polymerizing a radically polymerizable monomer to the polymerizable unsaturated double bonds in the copolymerized polyester resin. The grafting reaction temperature is desirably carried out in the range of 50°C to 120°C.
When carrying out the grafting reaction of a radically polymerizable monomer to a copolymerized polyester resin, a radically polymerizable monomer mixture and a radical initiator are simultaneously added to the copolymerized polyester resin dissolved in a solvent under heating. The reaction may be carried out by adding them, or by dropping them separately over a certain period of time, and then continuing heating with stirring for a certain period of time to advance the reaction. Alternatively, one type of monomer is added all at once, then another type of monomer and initiator are added dropwise separately over a certain period of time, and then the reaction is continued by continuing to heat with stirring for a certain period of time. Advancement is also performed as necessary.

The weight ratio of the copolymerized polyester resin and the radically polymerizable monomer that meets the purpose of the present invention is preferably in the range of polyester/radically polymerizable monomer = 40/60 to 95/5, more preferably 55/45. ~93/7, most preferably from 60/40 to 90/10. When the weight ratio of the copolymerized polyester resin is 40% by weight or less, the excellent performance of polyester, that is, high processability, excellent water resistance, and excellent adhesion to various films, cannot be fully demonstrated. On the contrary, it adds to the undesirable properties of acrylic resins, such as low processability, gloss, and water resistance. When the weight ratio of the polyester is 95% by weight or more, the amount of carboxyl groups in the radically polymerizable monomer graft chain responsible for making it hydrophilic is insufficient, making it impossible to obtain a good aqueous dispersion.

Desirable grafting reaction solvents suitable for the purposes of the present invention preferably consist of water-soluble organic solvents having a boiling point of 50 to 250°C. Here, the water-soluble organic solvent refers to one having a solubility in water at 20° C. of at least 10 g/L or more, preferably 20 g/L or more. Those with a boiling point exceeding 250°C are unsuitable because their evaporation rate is too slow and they cannot be removed sufficiently even by high-temperature baking of the coating film. Further, if the boiling point is 50°C or lower, when carrying out the grafting reaction using it as a solvent, an initiator that decomposes into radicals at a temperature of 50°C or lower must be used, which increases handling risks, which is undesirable. The first group of water-soluble organic solvents that can dissolve the copolymerized polyester resin well and relatively well dissolve the polymer of polymerizable monomers containing carboxyl group-containing polymerizable monomers include esters, such as acetic acid. ethyl, ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclic ethers such as tetrahydrofuran, dioxane, 1,3-dioxolane, glycol ethers such as ethylene glycol dimethyl ether, propylene glycol methyl ether, Propylene glycol propyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, carbitols such as methyl carbitol, ethyl carbitol, butyl carbitol, lower esters of glycols or glycol ethers Examples include ethylene glycol diacetate, ethylene glycol ethyl ether acetate, ketone alcohols such as diacetone alcohol, and further N-substituted amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc. .

On the other hand, water, alcohol, Among them, alcohols having 1 to 8 carbon atoms and polyhydric alcohols are particularly preferred as suitable for the purpose of the present invention. When the grafting reaction is carried out using a single solvent, only one type of water-soluble organic solvent of the first group can be selected. When using a mixed solvent, there are cases where multiple types are selected only from the first group of water-soluble organic solvents, and cases where at least one type of water-soluble organic solvent of the first group is selected and at least one type of water-soluble organic solvent of the second group is added. There is. Graft polymerization can be achieved both when the graft polymerization reaction solvent is a single solvent from the water-soluble organic solvents of the first group, and when it is a mixed solvent consisting of each of the water-soluble organic solvents of the first group and the second group. Polymerization reactions can be carried out. However, there are differences in the progress behavior of the grafting reaction, the appearance and properties of the grafting reaction product and the aqueous dispersion derived therefrom, and the mixture of water-soluble organic solvents of the first group and the second group, each consisting of one type of water-soluble organic solvent, is found to be different. Preferably, a solvent is used.

In other words, tetrahydrofuran, which belongs to the first group of water-soluble organic solvents and exhibits the strongest dissolving power for polyester resins, monomer mixtures containing carboxyl group-containing polymerizable monomers, and polymers derived therefrom, is used as a single solvent. In this case, the grafting reaction proceeds with a transparent appearance throughout. The viscosity of the system gradually increases, and in the latter stages of the grafting reaction, the viscosity increases significantly and the reaction may not be able to continue. In such cases, the reaction product remains transparent and rubbery, indicating the formation of a gel that is insoluble even in strong solvents. To avoid this, it is necessary to significantly reduce the resin concentration, which is not a rational method for manufacturing. On the other hand, a mixed solvent obtained by selecting methyl ethyl ketone from the first group of water-soluble organic solvents, selecting isopropyl alcohol from the second group of water-soluble organic solvents, and mixing both at a weight ratio of 75/25. When the solubility of the copolymerized polyester is adjusted using a system, the same polyester resin, the same radical polymerizable monomer composition ratio, the same polyester/radical polymerizable monomer ratio, Even when the reaction is carried out with the same resin solid content, neither thickening nor gelation of the system is observed as the grafting reaction progresses. Furthermore, the subsequent conversion into an aqueous system provides a good aqueous dispersion. This shows that the use of a mixed solvent system is a rational process that can increase the resin solid content concentration during production and reduce the amount of organic solvent used during production.

In the first group of solvents, the molecular chains of the copolymerized polyester resin are in an extended state with a large spread, whereas in the mixed solvent of the first group/second group, they are in a state of being entangled in a thread-like state with a small spread. was confirmed by measuring the viscosity of the copolyester resin in these solutions. Adjusting the dissolution state of the copolymerized polyester resin to make intermolecular crosslinking less likely to occur is effective in preventing gelation. Both highly efficient grafting and gelation suppression are achieved in the latter mixed solvent system. The weight ratio of the first group/second group solvent mixture is more preferably in the range of 95/5 to 10/90, still more preferably 90/10 to 20/80, and most preferably 85/15 to 30/70. The optimum mixing ratio is determined depending on the solubility of the polyester resin used.

The desired grafting reaction product that meets the purpose of the present invention is preferably neutralized with a basic compound, and by neutralization, it can be easily water-dispersed into fine particles having an average particle diameter of 500 nm or less. The basic compound is preferably a compound that volatilizes during coating film formation or during baking curing by adding a hardening agent, and ammonia, organic amines, etc. are preferable. Examples of desirable compounds include triethylamine, N,N-diethylethanolamine, N,N-dimethylethanolamine, aminoethanolamine, N-methyl-N,N-diethanolamine, isopropylamine, iminobispropylamine, ethylamine, Diethylamine, 3-ethoxypropylamine, 3-diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, dimethylaminopropylamine, methyliminobispropylamine, 3-methoxypropylamine, monoethanolamine, diethanolamine, triethanolamine Examples include ethanolamine. Depending on the carboxyl group content contained in the grafting reaction product, the basic compound can be at least partially neutralized or completely neutralized so that the pH value of the aqueous dispersion ranges from 5.0 to 9.0. It is desirable to use it as follows.

When carrying out water dispersion, the solvent contained in the grafting reaction product is removed in advance using an extruder under reduced pressure, and the grafting reaction product in the form of a melt or solid (pellet, powder, etc.) is converted into a base. It is also possible to create an aqueous dispersion by pouring it into water containing a basic compound and stirring under heat, but most preferably, water containing a basic compound is poured immediately after the grafting reaction is completed, Furthermore, it is desirable to continue heating and stirring to obtain an aqueous dispersion (one-pot method). Further, when the boiling point of the solvent is 100° C. or lower, part or all of the solvent used in the grafting reaction can be easily removed by distillation. The dispersion medium of the aqueous dispersion is water or a mixture with a water-soluble organic medium, and examples of this organic solvent include the above-mentioned graft polymerization solvents, preferably methyl ethyl ketone and isopropanol. The solid content concentration of the aqueous dispersion produced according to the present invention is 20 to 60% by weight, and it can be diluted by adding water if necessary.

For an aqueous dispersion suitable for the purpose of the present invention, it is preferable to use a copolyester having a weight average molecular weight of 5,000 to 50,000 as a raw material. If the weight average molecular weight is 5,000 or less, resin physical properties such as post-processability of the dried coating film tend to deteriorate. Furthermore, if the weight average molecular weight is even lower, the copolyester itself tends to be easily water-soluble, and a copolyester having a weight average molecular weight of 50,000 or more tends to be difficult to water-disperse.

In the present invention, it is preferable that the amount of the coating layer adhered is 0.010 to 0.200 g/m ² . This allows the coating layer to be uniformly controlled, and as a result, it becomes possible to deposit the inorganic thin film layer densely. In addition, the cohesive force within the coating layer is improved, and the adhesion between the base film, the coating layer, and the inorganic thin film layer is also increased, so that the water-resistant adhesion of the coating layer can be improved. The amount of adhesion of the coating layer is preferably 0.015 g/m 2 or more, more preferably 0.020 g/m ² or more, even more preferably 0.025 g/m ² or more, and preferably 0.190 g/m ² or less, More preferably it is 0.180 g/m ² or less, still more preferably 0.170 g/m ² or less. When the amount of the coating layer adhered exceeds 0.200 g/m ² , the cohesive force inside the coating layer becomes insufficient, and good adhesion may not be exhibited. Moreover, since the uniformity of the coating layer is also reduced, defects may occur in the inorganic thin film layer and gas barrier properties may be reduced. Moreover, the manufacturing cost becomes high, which is economically disadvantageous. On the other hand, if the thickness of the coating layer is less than 0.010 g/m ² , the base material cannot be sufficiently covered, and there is a possibility that sufficient gas barrier properties and interlayer adhesion may not be obtained.

In addition, the resin composition for the coating layer may contain various known inorganic and organic additives such as antistatic agents, slip agents, and anti-blocking agents, if necessary, to the extent that they do not impair the present invention. Good too.

The method for forming the coating layer is not particularly limited, and a conventionally known method such as a coating method can be employed, for example. Among the coating methods, preferable methods include an offline coating method and an inline coating method. For example, in the case of the in-line coating method carried out in the process of manufacturing the base film, the drying and heat treatment conditions during coating will depend on the coating thickness and equipment conditions, but after coating, it is immediately sent to the stretching process in the right angle direction. It is preferable to dry the film in the preheating zone or stretching zone of the process, and in such a case, the temperature is usually about 50 to 250°C.

[Inorganic thin film layer of polyamide base laminated film]
In the laminated film of the present invention, an inorganic thin film layer is laminated above the coating layer. The inorganic thin film layer is a thin film made of an inorganic oxide. The material 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, silicon oxide (silica), aluminum oxide (alumina), a mixture of silicon oxide and aluminum oxide (composite oxide) ) and the like are preferably mentioned. In particular, a composite oxide of silicon oxide and aluminum oxide is preferred from the standpoint 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 such that Al is in the range of 20 to 70% by mass of the metal component. If the Al concentration is less than 20%, the barrier properties may decrease, while if it exceeds 70%, the inorganic thin film layer tends to become hard, and the film may be destroyed during secondary processing such as printing or lamination. There is a risk that the barrier properties will deteriorate. Note that silicon oxide herein refers to various silicon oxides such as SiO and SiO ₂ or mixtures thereof, and aluminum oxide refers to various aluminum oxides such as AlO and Al ₂ O ₃ or mixtures thereof.

The thickness of the inorganic thin film layer is usually 1 to 100 nm, preferably 5 to 50 nm. If the thickness of the inorganic thin film layer is less than 1 nm, it may be difficult to obtain satisfactory gas barrier properties; on the other hand, even if the inorganic thin film layer is excessively thick, exceeding 100 nm, a corresponding improvement in gas barrier properties cannot be obtained. This is rather disadvantageous in terms of bending resistance and manufacturing cost.

There are no particular limitations on the method for forming the inorganic thin film layer, and known vapor deposition methods such as vacuum evaporation, sputtering, physical vapor deposition (PVD) such as ion plating, or chemical vapor deposition (CVD) may be used. Laws may be adopted as appropriate. Hereinafter, a typical method for forming an inorganic thin film layer will be explained using a silicon oxide/aluminum oxide thin film as an example. For example, when a vacuum evaporation method is employed, a mixture of SiO ₂ and Al ₂ O ₃ or a mixture of SiO ₂ and Al is preferably used as the evaporation raw material. Particles are usually used as these vapor deposition raw materials, and in this case, the size of each particle is preferably such that the pressure during vapor deposition does not change, and the preferable particle size is 1 mm to 5 mm. For heating, methods such as resistance heating, high frequency induction heating, electron beam heating, laser heating, etc. can be adopted. It is also possible to introduce oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor, etc. as a reactive gas, or to adopt reactive vapor deposition using means such as ozone addition or ion assist. Furthermore, the film forming conditions can also be changed arbitrarily, such as by applying a bias to the object to be deposited (the laminated film to be subjected to vapor deposition), heating or cooling the object to be deposited. The evaporation material, reaction gas, bias of the evaporation target, heating/cooling, etc. can be changed in the same way when sputtering or CVD is employed.

[Protective layer of polyamide base laminated film]
In the present invention, a protective layer is provided on the inorganic thin film layer. The inorganic thin film layer laminated on the plastic film is not a completely dense film, but is dotted with minute defects. By coating the specific protective layer resin composition described below on the inorganic thin film layer to form a protective layer, the resin in the protective layer resin composition permeates into the defective parts of the inorganic thin film layer, resulting in The effect of stabilizing gas barrier properties can be obtained. In addition, by using a material with gas barrier properties for the protective layer itself, the gas barrier performance of the laminated film can be greatly improved.

In the present invention, the amount of the protective layer deposited is preferably 0.10 to 0.60 g/m ² . This allows the protective layer to be uniformly controlled during coating, resulting in a film with less coating unevenness and defects. Furthermore, the cohesive force of the protective layer itself is improved, and the adhesion between the inorganic thin film layer and the protective layer is also strengthened. The amount of adhesion of the protective layer is preferably 0.13 g/m ² or more, more preferably 0.16 g/m ² or more, even more preferably 0.19 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. If the coating weight of the protective layer exceeds 0.600 g/ ^m2 , the gas barrier properties will improve, but the cohesive force inside the protective layer will be insufficient, and the uniformity of the protective layer will also decrease, resulting in uneven coating appearance. Defects may occur or gas barrier properties and adhesive properties may not be sufficiently developed. On the other hand, if the thickness of the protective layer is less than 0.10 g/m ² , sufficient gas barrier properties and interlayer adhesion may not be obtained.

In the present invention, urethane resin is used for the protective layer. The urethane resin has good adhesion to the inorganic thin film layer due to the presence of a polar urethane bonding part, and the resin easily penetrates into the defective part. Furthermore, since there is a crystal part with high cohesive force due to hydrogen bonds between urethane bonds, stable gas barrier performance can be obtained. Furthermore, since highly flexible amorphous parts also exist, the softness of the surface can be optimized by controlling the ratio of amorphous parts to crystalline parts. The urethane resin is preferably a water-dispersed one that has high polarity and good wettability to the inorganic thin film layer. Further, as the hardening type of resin, a thermosetting resin is preferable from the viewpoint of production stability.

(Urethane resin (A))
The urethane resin (A) can be obtained by reacting the following polyisocyanate component (B) with the following polyol component (C) by a conventional method. Furthermore, chain extension can be achieved by reacting a low-molecular compound having two or more active hydrogens, such as a diol compound (for example, 1,6-hexanediol, etc.) or a diamine compound (for example, hexamethylene diamine, etc.), as a chain extender. is also possible.

(B) Polyisocyanate component The polyisocyanate component (B) that can be used in the synthesis of the urethane resin (A) includes aromatic polyisocyanates, alicyclic polyisocyanates, aliphatic polyisocyanates, 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-tolylene diisocyanate or a mixture thereof) (TDI), phenylene diisocyanate (m-, p-phenylene diisocyanate or a mixture thereof), 4,4 '-Diphenylcyisocyanate, 1,5-naphthalene diisocyanate (NDI), diphenylmethane diisocyanate (4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate or mixtures thereof) (MDI) , 4,4'-toluidine diisocyanate (TODI), and 4,4'-diphenyl ether diisocyanate. Examples of the araliphatic diisocyanate include xylylene diisocyanate (1,3- or 1,4-xylylene diisocyanate or a mixture thereof) (XDI), tetramethylxylylene diisocyanate (1,3- or 1,4-tetramethyl Examples include xylylene diisocyanate (or a mixture thereof) (TMXDI), ω,ω'-diisocyanate-1,4-diethylbenzene, and the like.

Examples of the alicyclic diisocyanate include 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isocyanate), holodiisocyanate, IPDI), methylene bis(cyclohexyl isocyanate) (4,4'-, 2,4'- or 2,2'-methylene bis(cyclohexyl isocyanate)) (hydrogenated MDI), methylcyclohexane diisocyanate (methyl-2,4- Examples include cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), bis(isocyanatemethyl)cyclohexane (1,3- or 1,4-bis(isocyanatemethyl)cyclohexane or a mixture thereof) (hydrogenated XDI), and the like.

Examples of aliphatic diisocyanates include trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), hexamethylene Diisocyanate, pendamethylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methylcaffeate, etc. can be mentioned.

(C) Polyol component As the polyol component (especially diol component), anything from low molecular weight glycols to oligomers can be used, but from the viewpoint of gas barrier properties, alkylene glycols (e.g. ethylene glycol, propylene glycol, trimethylene glycol) are usually used. , (poly)oxy Low molecular weight glycols such as C2-4 alkylene glycols (diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, etc.) are used. Preferred glycol components include C2-8 polyol components [for example, C2-6 alkylene glycols (especially ethylene glycol, 1,2- or 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol), di- or trioxyC2-3 alkylene glycols (diethylene glycol, triethylene glycol, dipropylene glycol, etc.), and particularly preferred diol components are C2-8 alkylene glycols (especially C2 -6 alkylene glycol).

These diol components can be used alone or in combination of two or more. Furthermore, if necessary, aromatic diols (e.g., bisphenol A, bishydroxyethyl terephthalate, catechol, resorcinol, hydroquinone, 1,3- or 1,4-xylylene diol or mixtures thereof, 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. Furthermore, if necessary, a trifunctional or higher functional polyol component, for example, a polyol component such as glycerin, trimethylolethane, trimethylolpropane, etc. can be used in combination. The polyol component preferably contains at least a C2-8 polyol component (particularly a C2-6 alkylene glycol). The proportion of the C2-8 polyol component (particularly C2-6 alkylene glycol) in 100% by mass of the polyol component can be selected from a range of about 50 to 100% by mass, and is usually preferably 70% by mass or more and 100% by mass or less, More preferably, it is 80% by mass or more and 100% by mass or less, and even more 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 araliphatic diisocyanate component as a main component from the viewpoint of improving gas barrier properties and cohesive strength. Among these, it is particularly preferable to contain a metaxylylene diisocyanate component. By using the above resin, the cohesive force of urethane bonds can be further increased due to the stacking effect of aromatic rings, and as a result, good gas barrier properties and adhesion can be obtained.

The urethane resin preferably has a carboxylic acid group (carboxyl group) from the viewpoint of improving 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 or dimethylolbutanoic acid may be introduced as a copolymerization component as a polyol component. Moreover, if a carboxylic acid group-containing urethane resin is synthesized and then neutralized with a salt forming agent, an aqueous dispersion of the urethane resin can be obtained. Specific examples of salt forming agents include ammonia, trialkylamines such as trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, and tri-n-butylamine; -alkylmorpholines, N-dialkylalkanolamines such as N-dimethylethanolamine, N-diethylethanolamine, and the like. 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 within the range of 10 to 60 mgKOH/g. It is more preferably within the range of 15 to 55 mgKOH/g, and even more preferably within the range of 20 to 50 mgKOH/g. If the acid value of the urethane resin is within the above range, the liquid stability will be improved when it is made into an aqueous dispersion, and the protective layer can be deposited uniformly on the highly polar inorganic thin film layer, so the coat appearance will be improved. Becomes good.

The urethane resin of the present invention preferably has a glass transition temperature (Tg) of 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher. By setting Tg to 100° C. or higher, the cohesive force of the resin is improved, and the adhesiveness is excellent in a wet state where water is present.

The urethane resin of the present invention may contain various crosslinking agents for the purpose of improving the cohesive force and water-resistant adhesion of the film, as long as the gas barrier properties are not impaired. Examples of the crosslinking agent include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, and epoxy compounds. Among these, silicon-based crosslinking agents or carbodiimide compounds are particularly preferred from the viewpoint of improving water-resistant adhesion to the inorganic thin film layer.

As the silicon-based crosslinking agent, a silane coupling agent is preferable from the viewpoint of crosslinking between an inorganic substance and an organic substance. As the silane coupling agent, hydrolyzable alkoxysilane compounds such as halogen-containing alkoxysilanes (2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, chloroC2-4 alkyltriC1-4 alkoxysilane such as ethoxysilane), alkoxysilanes having epoxy groups [2-glycidyloxyethyltrimethoxysilane, 2-glycidyloxyethyltriethoxysilane, 3-glycidyloxypropyltrimethoxy Silane, glycidyloxyC2-4alkyltriC1-4alkoxysilane such as 3-glycidyloxypropyltriethoxysilane, glycidyloxydiC2- such as 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, etc. 4-alkyl diC1-4 alkoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyltri (Epoxycycloalkyl) C2-4 alkyltriC1-4 alkoxysilane such as methoxysilane], alkoxysilane having an amino group [2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, etc.] AminoC2-4alkyltriC1-4alkoxysilane such as ethoxysilane, aminodiC2-4alkyldiC1-4alkoxysilane such as 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 2-[N-( (2-aminoethyl)amino]ethyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltriethoxysilane, etc. 2-AminoC2-4alkyl)aminoC2-4alkyltriC1-4alkoxysilane, 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane, 3-[N-(2-aminoethyl)amino ] (amino diC2-4 alkyl diC2-4 alkyldiC1-4 alkoxysilane such as propylmethyldiethoxysilane), alkoxysilane having a mercapto group (2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane) , mercapto C2-4 alkyltriC1-4 alkoxysilane such as 3-mercaptopropyltriethoxysilane, mercapto diC2-4 alkyldiC1-4 alkoxysilane such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc. etc.), alkoxysilanes having a vinyl group (vinyltriC1-4 alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.), alkoxysilanes having an ethylenically unsaturated bond group [2-(meth)acryloxyethyltri (Meth)acryloxyC2-4alkyltriC1 such as methoxysilane, 2-(meth)acryloxyethyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, etc. Examples include (meth)acryloxydiC2-4alkyldiC1-4alkoxysilanes such as -4 alkoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane. . These silane coupling agents can be used alone or in combination of two or more. Among these silane coupling agents, silane coupling agents having an amino group are preferred.

The silane coupling agent is preferably added in the protective layer in an amount of 0.25 to 3.00% by mass, more preferably 0.5 to 2.75% by mass, and still more preferably 0.75 to 2.50% by mass. It is. If the amount added exceeds 3.00% by mass, the film will be cured and the cohesive force will be improved, but some unreacted portions will also be produced, which may reduce the adhesion between the layers. On the other hand, if the amount added is less than 0.25% by mass, sufficient cohesive force may not be obtained.

Examples of carbodiimide compounds include monocarbodiimide compounds and polycarbodiimide compounds. Examples of monocarbodiimide compounds include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, di-β-naphthylcarbodiimide, and the like. I can .

As the polycarbodiimide compound, those produced by conventionally known methods can be used. For example, it can be produced by synthesizing isocyanate-terminated polycarbodiimide through a condensation reaction of diisocyanate with removal of carbon dioxide.

Examples of diisocyanates that are raw materials for synthesizing polycarbodiimide compounds include isomers of toluylene diisocyanate, aromatic diisocyanates such as 4,4-diphenylmethane diisocyanate, aromatic aliphatic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate, and 4,4-diphenylmethane diisocyanate. , 4-dicyclohexylmethane diisocyanate, alicyclic diisocyanates such as 1,3-bis(isocyanatemethyl)cyclohexane, hexamethylene diisocyanate, and aliphatic diisocyanates such as 2,2,4-trimethylhexamethylene diisocyanate. From the viewpoint of yellowing, aromatic aliphatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanates are preferred.

Further, the above-mentioned diisocyanate may be used after controlling the molecule to an appropriate degree of polymerization using a compound that reacts with the terminal isocyanate such as monoisocyanate. Examples of the monoisocyanate for controlling the degree of polymerization by blocking the terminals of polycarbodiimide include phenyl isocyanate, tolylene isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate, and the like. In addition, compounds having an OH group, NH2 group, COOH group, or SO3H group can be used as the terminal capping agent.

The condensation reaction of diisocyanate with decarbonization proceeds in the presence of a carbodiimidization catalyst. Examples of the catalyst include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 3-methyl-1-phenyl-2 -phospholene-1-oxide and phospholene oxides such as 3-phospholene isomers thereof, and 3-methyl-1-phenyl-2-phospholene-1-oxide is preferred from the viewpoint of reactivity. Note that the amount of the catalyst used can be a catalytic amount.

It is desirable that the above-mentioned mono- or polycarbodiimide compounds be kept in a uniformly dispersed state when blended into water-based paints. It is preferable to add a hydrophilic segment to the molecular structure of the compound and blend it into the paint in the form of a self-emulsion or self-dissolution.

The degree of polymerization (n) of the polycarbodiimide compound is preferably 2 to 10, more preferably 3 to 7. If the degree of polymerization is low, the crosslinking reaction rate will be poor and the adhesion with the functional layer will be reduced, and if it is high, the compatibility with the resin will be poor and the haze may increase.

The carbodiimide compound used in the present invention may be water-dispersible or water-soluble. Water-soluble resins are preferred because they have good compatibility with other water-soluble resins and improve the transparency and crosslinking reaction efficiency of the coating layer.

In order to make a carbodiimide compound water-soluble, it is necessary to synthesize isocyanate-terminated polycarbodiimide by a condensation reaction involving removal of carbon dioxide from isocyanate, and then add a hydrophilic moiety having a functional group that is reactive with an isocyanate group. It can be manufactured by

Hydrophilic moieties include (1) quaternary ammonium salts of dialkylamino alcohols and quaternary ammonium salts of dialkylaminoalkylamines, (2) alkyl sulfonates having at least one reactive hydroxyl group, and (3) Examples include poly(ethylene oxide) end-capped with an alkoxy group, poly(propylene oxide), and a mixture of poly(ethylene oxide) and poly(propylene oxide). The number of repeating units of ethylene oxide and/or propylene oxide is preferably 3 to 50, more preferably 5 to 35. If the repeating unit is small, the compatibility with the resin will be poor and the haze will increase, and if the repeating unit is large, the water-resistant adhesiveness may be reduced. When the above hydrophilic moiety is introduced into the carbodiimide compound, it becomes (1) cationic, (2) anionic, and (3) nonionic. Among these, nonionic resins that are compatible with other water-soluble resins are preferred, regardless of their ionicity. In addition, in order to improve water resistance, nonionic properties are preferred since it is not necessary to introduce ionic hydrophilic groups.

The carbodiimide compound is preferably contained in the protective layer in an amount of 5% by mass or more and 30% by mass or less. More preferably, the content is 10% by mass or more and 25% by mass or less, and even more preferably 15% by mass or more and 20% by mass or less. If the content of the carbodiimide compound is less than 5% by mass, the cohesive force and water-resistant adhesiveness of the protective layer may not be sufficiently improved. On the other hand, if the content is 30% by mass or more, the gas barrier properties may deteriorate.

When forming a protective layer using a resin composition for a protective layer, a coating liquid (coating liquid) consisting of the polyurethane resin, ion-exchanged water, and a water-soluble organic solvent may be prepared, applied to a base film, and dried. As the water-soluble organic solvent, single or mixed solvents selected from alcohols such as ethanol and isopropyl alcohol (IPA), and ketones such as acetone and methyl ethyl ketone can be used. is preferably IPA.

The coating method of the resin composition for the protective layer is not particularly limited as long as it is a method of coating the film surface to form a layer. For example, conventional coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be employed.

When forming the protective layer, it is preferable to apply the resin composition for the protective layer and then heat dry it, and the drying temperature at that time is preferably 110 to 190°C, more preferably 130 to 190°C, even more preferably is 150-190°C. If the drying temperature is less than 110° C., the protective layer may be insufficiently dried, or the film formation of the protective layer may not proceed, resulting in a decrease in cohesive force and water-resistant adhesion, resulting in a decrease in hand tearability. On the other hand, if the drying temperature exceeds 190° C., too much heat is applied to the film, which may cause the film to become brittle or shrink, resulting in poor workability. In particular, by drying at 150°C or higher, preferably 160°C or higher, the formation of the protective layer will proceed effectively, and the adhesive area between the resin of the protective layer and the inorganic thin film layer will become larger, thereby improving water-resistant adhesion. can do. In addition to drying, additional heat treatment (for example, at 150 to 190° C.) is also more effective in promoting the formation of the protective layer.

[Lamination with heat-sealable resin layer]
When the laminated film of the present invention is used as a packaging material, it is necessary to include a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on the inorganic thin film layer side, that is, the protective layer surface, but it may also be provided on the outside of the base film (the surface opposite to the surface on which the coating layer is formed). The heat-sealable resin layer is usually formed by extrusion lamination or dry lamination. The thermoplastic polymer forming the heat-sealable resin layer may be one that can sufficiently exhibit sealant adhesive properties, such as polyethylene resins such as HDPE, LDPE, and LLDPE, polypropylene resins, and ethylene-vinyl acetate copolymers. , ethylene-α-olefin random copolymer, ionomer resin, etc. can be used. The thickness of the heat-sealable resin layer is preferably 20 μm or more, more preferably 25 μm or more, even more preferably 30 μm or more, and preferably 80 μm or less, more preferably 75 μm or less, and still more preferably 70 μm or less. If the thickness is less than 20 μm, productivity will be poor. On the other hand, if it is 80 μm or more, the cost will increase and the transparency will also deteriorate.

[Other layers]
The laminated film of the present invention may have at least one printed layer, another plastic base material, and/or paper base material laminated between the polyester film and the polyamide base film.

[Adhesive layer]
As the adhesive layer used in the present invention, a general-purpose laminating adhesive can be used. For example, poly(ester) urethane type, polyester type, polyamide type, epoxy type, poly(meth)acrylic type, polyethyleneimine type, ethylene-(meth)acrylic acid type, polyvinyl acetate type, (modified) polyolefin type, polybutadiene type. Solvent-based, water-based, or hot-melt type adhesives whose main component is a wax-based adhesive, a wax-based adhesive, a casein-based adhesive, or the like can be used. Among these, urethane-based or polyester-based materials are preferable in consideration of heat-and-moisture resistance that can withstand retort treatment and flexibility that can follow dimensional changes of each base material. Examples of laminating methods for the adhesive layer include direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fontaine coating, and others. The coating amount after drying is preferably 1 to 8 g/m ² in order to develop sufficient adhesion after retorting. More preferably 2 to 7 g/m ² , still more preferably 3 to 6 g/m ² . If the coating amount is less than 1 g/m ² , it becomes difficult to bond the entire surface, and the adhesive strength decreases. On the other hand, if it exceeds 8 g/m ² or more, it takes time for the film to completely cure, unreacted substances tend to remain, and the adhesive strength decreases.

As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks can be preferably used. Examples of resins used in the printing ink include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. Printing inks contain known antistatic agents, light blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, antifoaming agents, crosslinking agents, anti-blocking agents, antioxidants, etc. It may also contain additives. The printing method for providing the printed layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing 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 other plastic base materials and paper base materials, paper, polyester resin, biodegradable resin, etc. are preferably used from the viewpoint of obtaining sufficient rigidity and strength of the laminate. Further, in order to obtain a film with excellent mechanical strength, a stretched film such as a biaxially stretched polyester film is preferable.

The laminate of the present invention preferably has an oxygen permeability of 5 ml/ ^m2・d・MPa or less both before and after retort treatment under conditions of 23°C x 65% RH in order to exhibit good gas barrier properties. . Furthermore, by controlling the above-mentioned protective layer components and the amount of adhesion, it is possible to make it preferably 4 ml/m ² ·d · MPa or less, more preferably 3 ml/m ² ·d · MPa or less. When the oxygen permeability exceeds 5 ml/m ² ·d·MPa, it becomes difficult to support applications requiring high gas barrier properties. On the other hand, if the oxygen permeability before and after retort treatment is less than 1 ml/ ^m2・d・MPa, the barrier performance is excellent, but it becomes difficult for the residual solvent to permeate to the outside of the bag, making it relatively difficult to penetrate the contents. This is not preferable since the amount of migration may increase. A preferable lower limit of the oxygen permeability is 1 ml/m ² ·d·MPa or more.

The laminated body of the present invention preferably has a wet laminate strength of 1.5 N/15 mm or more, more preferably 2.0 N/15 mm or more, under 23°C x 65% RH conditions before and after retort treatment. Preferably it is 2.5N/15mm or more. If the laminate strength is 1.5 N/15 mm or less, peeling may occur due to bending load or liquid contents, and there is a risk that the barrier properties may deteriorate or the contents may leak out. Furthermore, there is also a possibility that the ease of cutting by hand may deteriorate.

Next, the present invention will be explained in detail using Examples and Comparative Examples, but the present invention is of course not limited to the following Examples. In addition, unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."
The evaluation method used in the present invention is as follows.

(1) Preparation of laminates for evaluation Apply a urethane-based two-component curing adhesive ("Takelac" manufactured by Mitsui Chemicals, Inc.) to the surface opposite to the protective layer surface of the gas barrier layer laminate film obtained in the Examples and Comparative Examples. A 12 μm thick polyester film (Toyobo Co., Ltd.'s "E5100") was dried using a mixture of "Takenate (registered trademark) A525S" and "Takenate (registered trademark) A50" at a ratio of 13.5:1 (mass ratio). A 70 μm thick unstretched polypropylene film (“P1147” manufactured by Toyobo Co., Ltd.) was bonded to the protective layer surface of the laminated film as a heat-sealable resin layer using the same adhesive using a dry lamination method. A laminate gas barrier laminate for evaluation (hereinafter sometimes referred to as "laminate laminate A") was obtained by aging at 40° C. for 4 days. Note that the thickness of the adhesive layer formed of the urethane-based two-component curing adhesive after drying was about 4 μm in all cases.

(2) Oxygen permeability evaluation method Regarding the laminate A produced in the above (1), an oxygen permeability measuring device ("OX-TRAN (registered trademark) 1/ 50''), the normal oxygen permeability was measured under an atmosphere of a temperature of 23° C. and a humidity of 65% RH. The oxygen permeability was measured in the direction in which oxygen permeated from the base film side of the laminate to the heat-sealable resin layer side. On the other hand, the laminate produced in (1) above was subjected to moist heat treatment by holding it in hot water at 120°C for 30 minutes, dried at 40°C for 2 days (48 hours), and the resulting wet heat treatment The oxygen permeability (after retort) of the laminate was measured in the same manner as above.

(3) Evaluation method of laminate strength
The laminate laminate A produced above was cut into a test piece with a width of 15 mm and a length of 200 mm, and was tested using a Tensilon universal material testing machine (manufactured by Toyo Baldwin Co., Ltd., "Tensilon UMT- The laminate strength (normal state) was measured using a test tube (Model II-500). The laminate strength was measured by applying water between the metal oxide layer (laminated film layer) and the nylon film layer of each laminated film obtained in Examples and Comparative Examples at a tensile speed of 200 mm/min. The strength was measured when peeled at a peel angle of 90 degrees.
On the other hand, the laminate laminate A produced above was subjected to a retort treatment for 30 minutes in which it was kept in pressurized hot water at a temperature of 120°C, and then the above-mentioned laminate was immediately removed from the obtained laminate laminate after the retort treatment. A test piece was cut out in the same manner, and the laminate strength (after retort treatment) was measured in the same manner as above.

(4) Method for evaluating residual solvent migration properties Using a test sealer (manufactured by Seibu Kikai Co., Ltd.) on all sides of the laminate laminate A produced in (1) above, seal a 10 mm wide sheet at 180°C x 2 kg x 2 seconds. Seal was performed to create a bag with inner dimensions of 52 mm x 115 mm. After storing the above-mentioned bag at 40℃ for 7 days, immediately after opening the bag, insert an odor sensor (XP-329IIIR manufactured by Shin Cosmos Electric Co., Ltd.) into the bag, measure the value after 1 minute, and check the solvent migration. The presence or absence of sex was determined as follows.

Value 800 or less: Migration ○
Value 800 or more: Migration ×

Each material used for forming the coating 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>
[Polyester resin (A)]
As the polyester resin, "AGN201" (solid content 25%) manufactured by Takemoto Yushi Co., Ltd., which is a water-dispersible acrylic graft polyester resin containing self-crosslinking maleic anhydride as a graft chain, was prepared.

[Urethane resin (B)]
As the urethane resin, a commercially available metaxylylene group-containing urethane resin dispersion ("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. Further, the ratio of aromatic or araliphatic diisocyanate to the entire polyisocyanate component measured by 1H-NMR was 85 mol%.

[Silane coupling agent (C)]
As a silane coupling agent, a commercially available "(registered trademark) KBM603" manufactured by Shin-Etsu Chemical Co., Ltd. (solid content 100%) was prepared.

[Urethane resin (D)]
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. Further, the ratio of aromatic or araliphatic diisocyanate to the entire polyisocyanate component measured by 1H-NMR was 55 mol%.

[Gas barrier ethylene-vinyl alcohol resin composition coating liquid (E)]
<Preparation of ethylene-vinyl alcohol copolymer solution>
Ethylene-vinyl alcohol copolymer (trade name: Soarnol (registered trademark) V2603, manufactured by Nippon Gosei Kagaku Co., Ltd., ethylene-vinyl acetate copolymer) was added to a mixed solvent of 20.996 parts of purified water and 51 parts of n-propyl alcohol (NPA). Add 15 parts of the polymer obtained by saponifying the polymer, ethylene ratio 26 mol%, saponification degree of vinyl acetate component approximately 100%, hereinafter abbreviated as EVOH), and hydrogen peroxide solution with a concentration of 30%. 13 parts and 0.004 parts of FeSO4 were added, heated to 80° C. with stirring, and reacted for about 2 hours. Thereafter, the mixture was cooled, catalase was added to 3000 ppm, residual hydrogen peroxide was removed, and a nearly transparent ethylene-vinyl alcohol copolymer solution (EVOH solution) with a solid content of 15% was obtained.
<Preparation of inorganic layered compound dispersion>
4 parts of montmorillonite (trade name: Kunipia (registered trademark) F, manufactured by Kunimine Kogyo Co., Ltd.), which is an inorganic layered compound, was added to 96 parts of purified water with stirring, and the mixture was sufficiently stirred using a high-pressure dispersion device at a pressure of 50 MPa. Dispersed. Thereafter, the mixture was kept at 40° C. for one day to obtain an inorganic layered compound dispersion having a solid content of 4%.
<Additives>
Zirconium chloride (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd., trade name: Zircosol (registered trademark) ZC-20, solid content 20%)
<Preparation of coating liquid (E)>
31.75 parts of EVOH solution was added to 62.30 parts of mixed solvent A (a solvent consisting of 40% purified water and 60% n-propyl alcohol), and the mixture was thoroughly stirred and mixed. Furthermore, 5.95 parts of an inorganic layered compound dispersion liquid was added to this solution while stirring at high speed. To 100 parts of this mixed solution, 3 parts of cation exchange resin was added and stirred for 1 hour at a stirring speed that did not crush the ion exchange resin to remove cations. Only the resin was filtered off using a strainer. The mixed solution obtained from the above operation was further dispersed in a high-pressure dispersion device at a pressure of 50 MPa, and then 0.75 part of zirconium chloride oxide and 2.0 parts of mixed solvent A2. 25 parts were mixed and stirred, and the mixture was filtered through a 255 mesh filter to obtain a protective layer coating liquid 3 having a solid content of 5%.

[Carbodiimide crosslinking agent (F)]
As a carbodiimide crosslinking agent, commercially available "Carbodilite (registered trademark) SV-02" manufactured by Nisshinbo (solid content: 40%) was prepared.

[Gas barrier protective layer solution (G)]
A solution obtained by hydrolyzing tetraethoxysilane with 0.02 mol/L hydrochloric acid was added to a 5% by weight aqueous solution of polyvinyl alcohol resin (PVA) with a degree of saponification of 99% and a degree of polymerization of 2400, with a weight ratio of SiO2/PVA = 60/40. A gas barrier protective layer solution (G) was obtained.

Example 1
(1) Preparation of coating liquid 1 used for coating layer Coating liquid 1 was prepared by mixing the following coating materials. Here, the mass ratio of the polyester resin (A) in terms of solid content is as shown in Table 1.

Water 33%
Isopropanol 7%
Polyester resin (A) 60%

(2) Preparation of coating liquid 2 used for protective layer Coating liquid 2 was prepared by mixing the following coating materials. Here, the mass ratio of the urethane resin (B) in terms of solid content is as shown in Table 1.

water 30%
Isopropanol 30%
Urethane resin (B) 40%

(3) Production of polyamide base film and coating with coating liquid 1 (lamination of coating layer)
Polycaproamide was heated and melted at 260°C with a screw extruder, extruded into a sheet from a T-die, and then this unstretched sheet was longitudinally stretched 3.3 times at 80°C between a heating roll and a cooling roll. . Then, the above coating liquid 1 was applied to one side of the obtained uniaxially stretched film by the fountain bar coating method. Next, the film was introduced into a tenter, stretched 4.0 times in the transverse direction at 120°C, and then heat-set at 215°C to form a coating layer of 0.075 g/m ² on the biaxially stretched polyamide film with a thickness of 15 μm. A laminated film was obtained.

(4) Formation of inorganic thin film layer A composite oxide layer of silicon dioxide and aluminum oxide was formed as an inorganic thin film layer on the coating layer forming surface of the film obtained in (3) above by electron beam evaporation. As the vapor deposition source, SiO ₂ (purity 99.9%) and Al ₂ O ₃ (purity 99.9%) in the form of particles of about 3 mm to 5 mm were used. Here, the composition of the composite oxide layer was SiO ₂ /Al ₂ O ₃ (mass ratio) = 70/30. Further, the film thickness of the inorganic thin film layer (SiO ₂ /Al ₂ O ₃ composite oxide layer) in the film thus obtained (inorganic thin film layer/coating layer-containing film) was 13 nm. In this way, a vapor-deposited film including a coating layer and an inorganic thin film layer was obtained.

(5) Coating coating liquid 2 on vapor deposited film (lamination of protective layer)
Coating liquid 2 prepared in the above (2) was applied by gravure roll coating onto the inorganic thin film layer of the vapor-deposited film obtained in (4) and dried at 190°C to obtain a protective layer. The coating amount after drying was 0.27 g/m ² (Dry).
In the manner described above, a polyamide base laminate film having a coating layer/inorganic thin film layer/protective layer on the base film was produced. Regarding the obtained laminate film, a laminate laminate was prepared as described above, and oxygen permeability, laminate strength, and solvent transferability were evaluated. The results are shown in Table 1.

(Examples 2 to 7, Comparative Examples 2 to 5)
In preparing the coating solution for forming the protective layer, lamination was carried out in the same manner as in Example 1, except that the type of base material, the amount of resin blended, the amount of adhesion, and the type were changed as shown in Table 1. Films and laminates were produced and evaluated for oxygen permeability, laminate strength, tear strength, and solvent migration. The results are shown in Table 1.

According to the present invention, when a gas barrier laminate comprising a coating layer, an inorganic thin film layer, and a protective layer is formed, it has excellent water-resistant adhesion, so no peeling occurs even when subjected to severe moist heat treatment such as retort treatment. It was found that there were no problems with the barrier properties deteriorating or the contents leaking out. It was also found that because a barrier layer is provided as an intermediate layer and is more permeable than a polyester-based barrier film, residual solvent is less likely to transfer to the contents in a one-way manner. Moreover, since the laminated film of the present invention can be manufactured easily with fewer processing steps, it is excellent in both economical efficiency and production stability, and can provide a gas barrier laminate with uniform characteristics.

Claims (4)

A laminate laminate formed by laminating a polyester film, a polyamide base laminate film, and a heat-sealable resin, wherein the polyamide base laminate film has a coating layer and an inorganic thin film layer on at least one side of the polyamide base film. and a protective layer are laminated in this order with or without other layers, the inorganic thin film layer being formed of aluminum oxide or a composite oxide of silicon oxide and aluminum oxide. , the coating layer contains a polyester resin, the protective layer contains a urethane resin containing metaxylylene groups, the urethane resin has an acid value in the range of 10 to 60 mgKOH/g, and a glass transition temperature of 100° C. or higher. A laminate laminate, characterized in that the laminate laminate has an oxygen permeability of 5 ml/m ² ·d·MPa or less before and after retort treatment . The laminate according to claim 1, wherein the protective layer contains at least one of a silicon-based crosslinking agent and a carbodiimide. 3. The laminate according to claim 1, wherein the polyester resin contained in the coating layer is a maleic anhydride grafted polyester resin. The laminate according to any one of claims 1 to 3, wherein the inorganic thin film layer is a layer made of a composite oxide of silicon oxide and aluminum oxide.