JP2023096393A - Laminated film and package - Google Patents

Abstract

To provide a laminated film capable of maintaining adhesion with an inorganic layer even under a heating condition such as retort treatment, and exhibiting a high gas barrier property even under a high humidity condition.SOLUTION: There is provided a laminated film that has a structure in which an intermediate resin layer (A) and an inorganic layer (B) are sequentially laminated on at least one side of a base film. The base film contains a polyester resin containing furandi-carboxylic acid as a dicarboxylic acid component and ethylene glycol as a diol component.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a laminated film and a package comprising a polyester resin film as a base film.

BACKGROUND ART Laminated films are widely used as packaging films for packaging foodstuffs, medical products, industrial parts, etc., because they prevent corrosion and putrefaction of contents and enable long-term storage. Therefore, this type of laminated film is required to have water vapor barrier properties and oxygen barrier properties.
In addition, for food packaging, adhesiveness that can maintain adhesion even when exposed to severe conditions such as retort treatment is required.

Conventionally, a plastic film is used as a base material, and a layer (referred to as an "inorganic layer") mainly composed of an inorganic substance such as an inorganic oxide deposition layer is formed on the surface of the base material to provide gas barrier properties. BACKGROUND ART Laminated films are widely used as packaging materials for articles that require blocking of various gases such as water vapor and oxygen in fields such as deterioration-preventive packaging for foods, industrial goods, pharmaceuticals, and the like.
In addition to packaging applications, such gas-barrier laminated films have recently begun to be used for new applications such as liquid crystal display elements, solar cells, electromagnetic wave shields, touch panels, EL substrates, and color filters.

Various improvements have been studied for gas barrier laminated films having an inorganic layer.
For example, in Patent Document 1, at least one surface of a substrate film is sequentially coated with an anchor coat layer, an inorganic layer such as silicon oxide, and a coating layer containing a silane coupling agent and a barrier resin. is disclosed.
Further, Patent Document 2 discloses a laminated film having a structure in which an anchor layer and an inorganic layer are laminated in this order on at least one side of a base film, and the storage elastic modulus of the anchor layer at 120° C. (E ') is 10 MPa or more, and the thickness of the anchor layer is 0.02 to 5.00 μm.
Furthermore, in Patent Document 3, a laminated film having a configuration in which an anchor layer and an inorganic layer are sequentially laminated on at least one side of a base film, and an average line of 105 to 120 ° C. in thermomechanical analysis (TMA) A laminated film roll having an expansion coefficient of −7×10 ⁻⁴ to 0/° C. in the longitudinal direction and −1×10 ⁻³ to 0/° C. in the width direction is disclosed.

In recent years, biodegradable resins and resins using raw materials derived from biomass have been attracting attention as environmentally friendly or environmentally sustainable materials. To this end, many studies have been conducted. Among them, a polyester-based resin using furandicarboxylic acid (FDCA) as a dicarboxylic acid component (also referred to as a "furan-based polyester resin") can be produced from biomass-derived raw materials, and furthermore, polyethylene terephthalate (PET) and the like can be produced. Since they have common properties, they are materials to be particularly noted in the future (see Patent Document 4).

As a laminated film using a furan-based polyester resin, for example, Patent Document 5 discloses a laminated polyester film comprising a polyester film and a coating layer, wherein the polyester film contains a dicarboxylic acid component containing furandicarboxylic acid as a main component. and a glycol component containing ethylene glycol as a main component is biaxially oriented, wherein the coating layer is provided on at least one side of the polyester film, and the laminated polyester film is plane-oriented. A laminated polyester film is disclosed which has a coefficient ΔP of 0.005 or more and 0.200 or less and a thickness of 1 μm or more and 300 μm or less.

JP-A-10-76593 JP 2021-138066 A JP 2021-169163 A U.S. Pat. No. 2,551,731 WO2017/115737

Regarding the gas barrier laminated film having an inorganic layer on at least one side of the base film, when the above furan-based polyester resin was used as the material of the base film, the furan-based polyester resin did not shrink when heated. Due to its relatively large size, it has been found that the inorganic layer is easily peeled off from the substrate film when exposed to severe conditions such as retort treatment.

Therefore, the object of the present invention is to provide a laminated film having an inorganic layer on at least one side of the front and back sides of a base film using a furan-based polyester resin, maintaining adhesion with the inorganic layer even under heating conditions such as retort processing. The object of the present invention is to provide a laminated film capable of exhibiting high gas barrier properties even under high humidity.

[1] The present invention comprises a structure in which an intermediate resin layer (A) and an inorganic layer (B) are sequentially laminated on at least one of the front and back sides of a base film, and the base film comprises furandicarboxylic acid and dicarboxylic acid. A laminated film is proposed, which is a film containing a polyester resin containing ethylene glycol as a diol component and containing ethylene glycol as an acid component.

[2] The present invention also provides the laminated film according to [1], wherein the intermediate resin layer (A) contains one or more resins selected from the group consisting of polyester-based resins, urethane-based resins and acrylic-based resins. Suggest.
[3] The present invention also proposes the laminated film according to [2], wherein the intermediate resin layer (A) further contains an isocyanate compound.

[4] The present invention also provides any one of [1] to [3], wherein the inorganic layer (B) contains one or more inorganic materials selected from the group consisting of silicon oxide, silicon nitride and aluminum oxide. We propose a laminated film as described in .

[5] The present invention also proposes the laminated film according to any one of [1] to [4], wherein the base film has a thickness of 5 μm or more and 1000 μm or less.
[6] The present invention also proposes the laminated film according to any one of [1] to [5], wherein the intermediate resin layer (A) has a thickness of 5 nm or more and 5000 nm or less.
[7] The present invention also proposes the laminated film according to any one of [1] to [6], wherein the inorganic layer (B) has a thickness of 5 nm or more and 200 nm or less.

[8] The present invention also proposes the laminated film according to any one of [1] to [7], further comprising a surface resin layer (C) on the surface of the inorganic layer (B).

[9] The present invention also provides a water vapor transmission rate of 3.0 g/m ² /day or less at a temperature of 40° C. and a relative humidity of 90% measured according to JIS Z0208 (1976) [1] to [8]. ] is proposed.
[10] The present invention also provides that the oxygen transmission rate is 2.7 cc/m ² /day/atm or less under conditions of 25° C. and 80% relative humidity measured according to JIS K7126-2 (2006). 1] to [9], the laminated film is proposed.

[11] The present invention also proposes a package using the laminated film according to any one of [1] to [10].

In the laminated film proposed by the present invention, a polyester resin containing furandicarboxylic acid as a dicarboxylic acid component and ethylene glycol as a diol component is used as a base film, and an intermediate resin layer is provided on at least one side of the base film. By sequentially forming (A) and the inorganic layer (B), it is possible to maintain the adhesion with the inorganic layer (B) even under heating conditions such as retort treatment, and even under high humidity Gas barrier properties can be expressed.
Therefore, the laminated film proposed by the present invention is suitable as a packaging material for articles that require blocking of various gases such as water vapor and oxygen, particularly as a packaging material that may be subjected to heating conditions such as retort treatment. For example, it can be suitably used as a packaging material for foods, industrial goods, pharmaceuticals, and the like. In addition to packaging applications, it can be suitably used for various members such as liquid crystal display elements, solar cells, electromagnetic wave shields, touch panels, EL substrates, and color filters.

Next, the present invention will be described based on embodiments. However, the present invention is not limited to the embodiments described below.

<<Laminated film>>
A laminated film according to an example of the embodiment of the present invention (hereinafter also referred to as "laminated film of the present invention") includes an intermediate resin layer ( A) and an inorganic layer (B) are laminated in order.

<This base film>
The base film is a film containing a polyester resin (hereinafter also referred to as "PEF-based resin") containing furandicarboxylic acid as a dicarboxylic acid component and ethylene glycol as a diol component.
By including PEF-based resin in the base film, the furandicarboxylic acid is derived from biomass, and the furan ring included in the structure is compared with the benzene ring included in the structure of polyethylene terephthalate-based resin (PET-based resin). Due to its low motility, it is possible to increase the biomass-derived degree while exhibiting higher barrier properties than PET-based resins.

The base film preferably contains a PEF-based resin as a main component resin.
In addition, the above-mentioned "main component resin" means a resin that occupies the largest mass% of the resin components contained in the base film, and the total mass of the resin components contained in the base film is 100% by mass. When the mass ratio of the resin is 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more, A case of 100% by mass can be assumed.

(PEF resin)
The PEF-based resin used in the base film may be a polyester resin containing furandicarboxylic acid as a dicarboxylic acid component and ethylene glycol as a diol component. A polyester resin containing glycol as a main diol component is preferred.
In this case, the "main component" means the component with the largest mol% of the dicarboxylic acid component or the diol component. When the ratio of is 50 mol% or more, it can be assumed that it is 60 mol% or more.

The content of the furandicarboxylic acid is preferably 80 mol% or more, particularly 90 mol% or more, based on 100 mol% of the total dicarboxylic acid component constituting the PEF-based resin, from the viewpoint of gas barrier properties. is more preferred, and 95 mol % or more is particularly preferred.

The PEF-based resin may be copolymerized with a dicarboxylic acid component other than furandicarboxylic acid as the dicarboxylic acid component.
Other dicarboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, 4,4′-dicarboxybiphenyl, 5-sodiumsulfoisophthalic acid, and 1,4-cyclohexane. Alicyclic dicarboxylic acids such as dicarboxylic acids, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid and tetrahydrophthalic acid, oxalic acid, malonic acid, succinic acid and adipic acid , azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, octadecanedioic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, dimer acid and the like.
However, from the viewpoint of gas barrier properties, the copolymerization amount of the other dicarboxylic acid component is preferably 20 mol % or less with respect to 100 mol % of the total dicarboxylic acid component constituting the PEF resin. % or less, and particularly preferably 5 mol % or less.

The content of ethylene glycol is preferably 80 mol% or more, more preferably 90 mol% or more, based on 100 mol% of all diol components constituting the PEF resin, from the viewpoint of film stretchability. is more preferable, and among them, 95 mol % or more is particularly preferable.

The PEF-based resin may be copolymerized with a diol component other than ethylene glycol as the diol component.
Other glycol components include, for example, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1, 3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 1,10-decanediol, dimethyloltricyclodecane, diethylene glycol, Aliphatic glycols such as triethylene glycol, bisphenol A, bisphenol S, bisphenol C, bisphenol Z, bisphenol AP, ethylene oxide or propylene oxide adducts of 4,4'-biphenol, 1,2-cyclohexanedimethanol, 1 , 3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and other alicyclic glycols, polyethylene glycol and polypropylene glycol.
However, from the viewpoint of stretchability of the film, the copolymerization amount of the other glycol component is preferably 20 mol % or less, and 10 mol %, relative to 100 mol % of all the diol components constituting the PEF resin. % or less, and particularly preferably 5 mol % or less.

Examples of the polymerization method of the PEF resin include a direct polymerization method in which furandicarboxylic acid and ethylene glycol, and optionally other dicarboxylic acid components and diol components are directly reacted, and a dimethyl ester of furandicarboxylic acid (if necessary An arbitrary production method such as a transesterification method in which ethylene glycol (including other dicarboxylic acid methyl esters as necessary) and ethylene glycol (including other diol components as necessary) are transesterified can be used.

(other resin)
The base film may contain resin components other than PEF resins, such as polyamide resins, polystyrene resins, polyolefin resins, and polyester resins other than PEF resins.
However, in terms of mechanical properties and heat resistance, the content of other resins is preferably 30% by mass or less, more preferably 20% by mass or less, relative to the total resin components of the base film. , is particularly preferably 10% by mass or less, more preferably 5% by mass or less, and most preferably, the entire resin component of the polyester film is substantially a PEF resin.

(other ingredients)
The present base film may contain particles for the main purposes of roughening the film surface to impart lubricity and preventing the occurrence of scratches in each step.

The type of the particles is not particularly limited as long as they are particles capable of imparting lubricity. For example, silica calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, inorganic particles such as titanium oxide, acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, benzoguanamine resin organic particles such as These may be used individually by 1 type, or may be used in combination of 2 or more types among these.
The shape of the particles is not particularly limited. For example, it may be spherical, blocky, rod-shaped, or flat.
Further, the hardness, specific gravity, color, etc. of the particles are not particularly limited. Two or more types of these series of particles may be used in combination, if necessary.

The average particle size of the particles is preferably 5 μm or less, more preferably 0.01 μm or more or 3.0 μm or less, and more preferably 0.5 μm or more or 2.5 μm or less. If the average particle diameter of the particles is 5 μm or less, the surface roughness of the present base film does not become too rough. Problems in forming B) can be reduced.

The particle content is preferably 5% by mass or less based on 100% by mass of the base film, especially 0.0003% by mass or more or 3% by mass or less, especially 0.01% by mass or more or It is more preferably 2% by mass or less. By setting the particle content within the above range, it is possible to achieve both smoothness and transparency of the film, which is preferable.

The present base film can also contain conventionally known antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, ultraviolet absorbers, and the like, if necessary.

(Structure of base film)
The base film may be a single-layer film consisting only of a layer or film containing the PEF-based resin, or may be a multi-layer film containing one or more other layers. However, it is preferable that the layer or film containing the PEF resin is the main layer.
Here, the "main layer" means the layer having the largest layer thickness among the layers constituting the base film.
Moreover, when the present base film is a multilayer film, it can be made into a multilayer film by a general molding method such as co-extrusion or dry lamination.

(Thickness of base film)
The thickness of the base film can be appropriately selected depending on the application. It is preferable to wind the film into a roll form from the viewpoint of processing suitability.

(Physical properties of base film)
The present base film preferably has the following physical properties.

The storage modulus (E′) at 130° C. in the dynamic viscoelasticity measurement of the base film is preferably 10 to 1000 MPa from the viewpoint of gas barrier properties, especially 30 MPa or more or 700 MPa or less, among which 50 MPa or more or It is more preferably 500 MPa or less.

Furthermore, from the viewpoint of gas barrier properties, the peak temperature of the loss tangent (tan δ) in the dynamic viscoelasticity measurement of the base film is preferably 50 to 150 ° C., especially 60 ° C. or higher or 140 ° C. or lower. More preferably, the temperature is 70°C or higher or 130°C or lower.

(Manufacturing method of base film)
The base film can be formed by melt-extruding a resin composition containing a PEF-based resin by a general molding method such as melt-extrusion molding or hot pressing to form a film. However, it is not limited to this method.

The base film may or may not be stretched. In the case of a stretched film, a stretched film can be obtained by uniaxially or biaxially stretching according to a known method. Biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching.
Since the PEF-based resin contributes not only to gas barrier properties but also to stretchability, the film can be easily stretched. The thickness and the like of the film may be appropriately determined depending on the application.

<Intermediate resin layer (A)>
The laminated film of the present invention has a structure in which an intermediate resin layer (A) and an inorganic layer (B) are sequentially laminated on at least one side of the substrate film.
In the laminated film of the present invention, the intermediate resin layer (A) is a layer useful for improving the adhesion between the base film and the inorganic layer (B). It is also a useful layer for relieving stress generated in the inorganic layer (B) and improving barrier properties.

The intermediate resin layer (A) preferably contains a thermoplastic resin or a curable resin. Above all, from the viewpoint of gas barrier properties, it is a layer containing one or more resins (also referred to as "intermediate layer base resin") selected from the group consisting of thermoplastic resins such as polyester resins, urethane resins and acrylic resins. is preferred.

The polyester-based resin can be obtained by reacting a polyhydric carboxylic acid component and a polyhydric alcohol component.
Examples of the polyvalent carboxylic acid component include terephthalic acid, isophthalic acid, adipic acid, sebacic acid, azelaic acid and orthophthalic acid.
Examples of the polyhydric alcohol component include ethylene-glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, diethylene-glycol, neopentyl glycol, dipropylene glycol and 1,6-hexane. A diol etc. can be illustrated.

The urethane-based resin is a water-soluble or water-dispersible resin produced by reacting a polyhydroxy compound and a polyisocyanate compound according to a conventional method.
Examples of the polyhydroxy compound include polyethylene glycol, polypropylene glycol, polyethylene/propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaprolactone, poly Hexamethylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, glycerin and the like can be mentioned.

Examples of the polyisocyanate compound include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, an adduct of tolylene diisocyanate and trimethylolpropane, and an adduct of hexamethylene diisocyanate and trimethylolethane.

The acrylic resin is not particularly limited, and one obtained by polymerizing a polymerizable unsaturated monomer using a conventionally known polymerization method can be used.
Examples of polymerizable unsaturated monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (Meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate and other (meth)acrylic acid esters, and from the viewpoint of crosslinking with a crosslinkable compound after forming an acrylic resin, hydroxy Ethyl (meth) acrylate, hydroxypropyl (meth) acrylate, caprolactone-modified hydroxy (meth) acrylate, and polyester diol mono (meth) acrylate obtained from phthalic acid and propylene glycol, etc. (meth) acrylic monomers having hydroxyl groups, amino Examples include (meth)acrylic monomers having groups and other crosslinkable functional groups such as carboxyl groups, and (meth)acrylic monomers having acidic functional groups such as (meth)acrylic acid.

When the intermediate resin layer (A) is 100% by mass, it may contain 50% by mass or more of one or more resins selected from the group consisting of polyester-based resins, urethane-based resins and acrylic-based resins, that is, intermediate layer base resins. More preferably, it contains 60% by mass or more, and more preferably contains 70% by mass or more, 80% by mass or more, or 90% by mass or more (including 100% by mass).

Preferably, the intermediate resin layer (A) further contains a curing agent such as an isocyanate compound.

(Isocyanate compound)
Since the isocyanate-based compound functions as a curing agent, the inclusion of the isocyanate-based compound in the intermediate resin layer (A) can introduce a crosslinked structure into the intermediate resin layer (A). Furthermore, the intermediate resin layer (A) can be given appropriate rigidity and flexibility, and the gas barrier properties of the inorganic layer (B) can be enhanced by relaxing the stress remaining in the inorganic layer (B). Moreover, it becomes easy to improve the adhesiveness of a base film and an inorganic layer (B). Therefore, the intermediate resin layer (A) preferably contains an isocyanate compound.

Examples of isocyanate compounds include aliphatic polyisocyanates such as hexamethylene diisocyanate and dicyclohexylmethane diisocyanate, and aromatic polyisocyanates such as xylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenylene diisocyanate, tolidine diisocyanate and naphthalene diisocyanate. can be mentioned. Polyisocyanates having two or more isocyanate groups are preferred, and polyisocyanates having three or more isocyanate groups are more preferred from the viewpoint of gas barrier properties and adhesion to the base film and the inorganic layer.

By adjusting the content of the isocyanate-based compound, it is possible to introduce appropriate cross-linking into the intermediate resin layer (A), adjust the hardness and softness of the intermediate resin layer (A), and improve stress relaxation. properties and adhesiveness can be adjusted. From this point of view, the content of the isocyanate compound in the intermediate resin layer (A) is preferably 0.1 parts by mass or more, particularly 0.5 parts by mass or more, with respect to 100 parts by mass of the intermediate layer base resin. , 0.8 parts by mass or more, preferably 1.0 parts by mass or more. On the other hand, it is preferably 400 parts by mass or less, more preferably 200 parts by mass or less, more preferably 150 parts by mass or less, most preferably 100 parts by mass or less.

(Physical properties of intermediate resin layer (B))
The base film preferably has the following physical properties.

Regarding the storage elastic modulus (E′) at 130° C. in dynamic viscoelasticity measurement, the difference between the intermediate resin layer (B) and the base film is preferably 1000 MPa or less, especially 700 MPa or less, especially 500 MPa. More preferably:
In this case, the storage elastic modulus (E') of the intermediate resin layer (B) at 130°C is preferably the same as or lower than that of the base film.

Regarding the peak temperature of the loss tangent (tan δ) in dynamic viscoelasticity measurement, the difference between the intermediate resin layer (B) and the base film is preferably 100°C or less, especially 90°C or less, especially 80°C. °C or less is more preferable.
At this time, the peak temperature of the loss tangent (tan δ) of the intermediate resin layer (B) is preferably the same as or lower than that of the base film.

If the elastic modulus or tan δ of the intermediate resin layer (B) is within the above range compared to the PEF-based resin that is the main component resin of the base film, the heat shrinkage of the base film can be relaxed, for example. Since it is possible to suppress the influence thereof from reaching the inorganic layer, it is possible to maintain adhesion and gas barrier properties.
In addition, in order to impart the above viscoelasticity to the intermediate resin layer (A), for example, a method of adjusting the blending amount of the curing agent in the intermediate resin layer (A) can be mentioned. However, it is not limited to this method.

(thickness)
From the viewpoint of gas barrier properties, the thickness of the intermediate resin layer (A) is preferably 5 nm or more and 5000 nm or less, more preferably 10 nm or more and 2000 nm or less, and more preferably 20 nm or more and 1000 nm or less.

From the viewpoint of gas barrier properties and optical properties, the thickness of the intermediate resin layer (A) is preferably 5 to 1500% of the thickness of the inorganic layer (B), especially 10% or more or 1000% or less, especially 20%. More preferably, it is 500% or more.

(Method for forming intermediate resin layer (A))
As a method for forming the intermediate resin layer (A), one or more resins selected from the group consisting of polyester-based resins, urethane-based resins and acrylic-based resins, and other predetermined materials are mixed with a solvent to form a coating liquid. The intermediate resin layer (A) can be formed by applying the coating liquid onto the base film, drying it and, if necessary, curing it.

Other predetermined materials include, for example, photopolymerization initiators, cross-linking agents, particles, cross-linking catalysts, carbodiimide compounds, surfactants, polyalkylene oxides, quaternary ammonium salts of dialkylamino alcohols, hydroxyalkylsulfonates, and other hydrophilic materials. A monomer etc. can be mentioned.

Examples of the solvent include ketone solvents such as methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, diacetone alcohol and acetone; alcohol solvents such as pentanol, hexanol, heptanol and octanol; Ether solvents such as ethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate; methyl acetate, ethyl acetate, butyl acetate, methoxybutyl acetate, amyl acetate, propyl acetate, ethyl lactate, methyl lactate , ester solvents such as butyl lactate; organic solvents such as hydrocarbon solvents such as toluene, xylene, solvent naphtha, hexane, cyclohexane, ethylcyclohexane, methylcyclohexane, heptane, octane, and decane. These organic solvents may be used alone or in combination of two or more.
The composition for forming the intermediate resin layer (A) may contain water as a solvent, or may use a mixture of an organic solvent and water as a solvent. When the composition contains a solvent, the solid component is diluted with the solvent, resulting in good coatability.
The solvent may be added to the composition so that the solid concentration is about 0.1 to 50% by mass, for example.

As the coating method, for example, any coating method using a reverse roll coater, gravure coater, rod coater, air doctor coater, bar coater, spray, or the like can be employed.
After coating, the solvent can be evaporated using a known drying method such as hot air drying at a temperature of about 60 to 200° C., heat drying such as hot roll drying, or infrared drying.
The curing method may be either photocuring by irradiating ultraviolet rays or heat curing by heating. For example, when an isocyanate-based compound is blended, it is preferable to heat to 80° C. or higher for thermal curing.

<Inorganic layer (B)>
The laminated film of the present invention has a structure in which an intermediate resin layer (A) and an inorganic layer (B) are sequentially laminated on at least one side of the substrate film.
By forming the inorganic layer (B), permeation of gases such as water vapor and oxygen gas can be suppressed, and gas barrier properties can be exhibited.

The inorganic layer (B) is preferably a layer containing an inorganic substance, particularly an inorganic oxide, an inorganic nitride, or an inorganic oxynitride as a main component.
The "main material" means a material that accounts for 50% by mass or more, especially 70% by mass or more, especially 80% by mass or more, especially 90% by mass or more (including 100% by mass) of the inorganic layer (B). .

The inorganic substance as the main material constituting the inorganic layer (B) is selected from silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon oxycarbonitride, aluminum oxide, aluminum nitride, aluminum oxynitride and aluminum oxycarbide. At least one or two or more inorganic compounds can be mentioned.
Among these, one or more inorganic materials selected from the group consisting of silicon oxide, silicon nitride, and aluminum oxide are preferably included.

Examples of the inorganic layer (B) include a PVD inorganic layer formed by a physical vapor deposition (PVD) method, a plasma-assisted vapor deposition inorganic layer formed by a plasma-assisted vapor deposition method, and a chemical vapor deposition (CVD) method. It is preferably a CVD inorganic layer, a coated inorganic layer formed by a method of dispersing inorganic particles in an organic polymer and applying the layer, or the like.

When the inorganic layer (B) is 100% by mass, the inorganic substance preferably accounts for 70% by mass or more, more preferably 80% by mass or more, and more preferably 90% by mass or more.

The inorganic layer (B) may contain alkali metal ions or alkaline earth metal ions to improve gas barrier properties.

The inorganic layer (B) may contain organic substances in addition to inorganic substances.
By mixing an inorganic substance with an organic substance to form the inorganic layer (B), the inorganic layer (B) can be made a relatively flexible layer. By providing such a flexible layer, it may be possible to improve gas barrier properties. That is, when the surface of the present base film has a coarse protrusion or the like, this serves as a starting point to cause a minute defect called a pinhole on the surface of the inorganic layer (B), or the raw material to clump during thermal vapor deposition. The particles may fly and adhere to the surface of the inorganic layer (B), causing minute defects on the surface of the inorganic layer (B), and gas passing through voids caused by these defects may reduce the gas barrier properties. In such a case, the gas barrier property can be maintained by providing a flexible layer.
Examples of the organic substance include organic substances such as polyester resin, acrylic resin, urethane resin, and PVA, as well as organic fillers.

(Layer structure of inorganic layer (B))
The inorganic layer (B) may have a single-layer structure or a multi-layer structure of two or more layers.
For example, as an example of a multilayer structure of two or more layers, one layer thereof is an inorganic layer (B) consisting only of an inorganic substance such as an inorganic oxide, and the other layer is a layer containing an inorganic oxide and an organic substance. An example can be given.
Since the layer containing the inorganic oxide and the organic substance can be a flexible layer as described above, lamination of this layer can fill the defects and improve the gas barrier properties. There is
The term "flexible layer" as used herein includes the meaning of a layer that relaxes the stress of the inorganic layer (B) so as to correspond to applications that require flexibility, such as flexible applications.

(thickness)
The thickness of the inorganic layer (B) is preferably 5 nm or more and 200 nm or less, more preferably 10 nm or more or 150 nm or less, from the viewpoint of layer formability while maintaining transparency while ensuring desired gas barrier properties. More preferably, it is more preferably 15 nm or more or 100 nm or less. When there are multiple inorganic layers (B), it is the total thickness of them.
The layer thickness of the inorganic layer can be measured by preparing an ultra-thin section of the laminated film and observing it with a transmission electron microscope or the like.

(Method for forming inorganic layer (B))
Formation (film formation) of the inorganic layer (B) is performed by, for example, a vacuum heating deposition method, an electron beam method, a sputtering method, a physical vapor deposition (PVD) method such as an ion plating method, or a chemical vapor deposition (CVD) method. A known method such as can be used. Plasma assist may be combined with the PVD method and the CVD method. When the inorganic layer is a plurality of layers, a plurality of inorganic layer deposition methods may be used.
From the viewpoint of gas barrier properties, the PVD method is preferable, and for example, it is preferable to form an inorganic layer made of silicon oxide represented by SiOx (1.0<x≦2.0). If the value of x in SiOx is small, the gas barrier property is improved, and if the value of x is large, the colorless transparency is improved.
The composition of SiOx can be controlled by the composition of raw materials used, the type of reaction gas, the degree of vacuum, and the deposition rate, and the composition of SiOx can be analyzed by X-ray photoelectron spectroscopy (XPS) or the like.

When the PVD method is combined with plasma assist, it is preferable to deposit while ionizing the deposition material by plasma during vacuum deposition, or to irradiate gas ions from an ion source provided separately. Oxygen atoms can be efficiently incorporated into the inorganic layer by plasma assist, so that the transparency can be improved without lowering the gas barrier properties of the inorganic layer. In addition, since energy can be applied to the deposition material by plasma assist, a dense inorganic layer can be formed. In addition, since the excited species in the plasma are highly reactive, it is possible to easily control the oxidation, nitridation, carbonization, etc. of the evaporated material by introducing a gas such as oxygen, nitrogen, or acetylene.
Therefore, in the case of inorganic oxides such as SiOx and AlOx, even if the value of x is the same, a dense film structure can be obtained by combining plasma assist, compared to an inorganic layer obtained by PVD alone, and gas barrier properties can be improved.

<Surface resin layer (C)>
In the laminated film of the present invention, a surface resin layer (C) may be provided on the surface of the inorganic layer (B) for the purpose of protecting the inorganic layer (B) and improving gas barrier properties.

Main component resins of the surface resin layer (C) include, for example, polyvinyl alcohol-based resins, ethylene vinyl alcohol-based resins, polyurethane-based resins, polyester-based resins, polyolefin-based resins, acrylic-based resins, polyvinylidene chloride resins, and polyvinylpyrrolidone resins. resins such as ethyleneimine, isocyanate compounds, carbodiimide compounds, epoxy compounds, oxazoline compounds, and alkoxysilanes.
In addition, the above-mentioned "main component resin" means a resin that accounts for the largest mass % of the resin components contained in the surface resin layer (C), and the total mass of the resin components contained in the surface resin layer (C) is When 100% by mass, the mass ratio of the resin is 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. In some cases, it can be assumed that it is 100% by mass.

(thickness)
Although the thickness of the surface resin layer (C) is not particularly limited, it is preferably 10 to 1000 nm, more preferably 50 nm or more or 500 nm or less.

(Method for forming surface resin layer (C))
For forming the surface resin layer (C), known coating methods such as gravure coating, gravure reverse coating, kiss reverse gravure coating, spin coating, bar coating, and die coating can be used.
As for the drying method, for example, one or a combination of two or more methods of applying heat such as hot air drying, radiant heat drying, hot roll drying, high frequency irradiation, infrared irradiation and UV irradiation can be used.

<Physical properties of the laminated film of the present invention)
The laminated film of the present invention can have the following physical properties.

(Interlayer adhesion)
The laminated film of the present invention can maintain adhesion between the base film and the inorganic layer (B) through the specific intermediate resin layer (A).
In the laminated film of the present invention, the evaluation of the interlayer adhesion between the base film and the inorganic layer (B) is performed by the inorganic layer (B) of the laminated film of the present invention (when the surface resin layer (C) is provided, the surface resin layer The (C)) surface and the corona-treated surface of the unstretched polypropylene film were opposed to each other, and a test film was dry-laminated via a urethane-based adhesive for dry lamination. Using a machine, the peel strength was tested under the conditions of a test speed of 300 mm / min and a peel angle of 180 degrees. It can be evaluated by the peel strength of a peel test conducted under the same conditions.
The peel strength can be evaluated by whether it is 50 g/15 mm or more under any test conditions. 100 g/15 mm or more is more preferable, and 200 g/15 mm or more is even more preferable.

(Water vapor barrier property)
The laminated film of the present invention preferably has a water vapor transmission rate (WVTR) of 3.0 g/m ² /day or less at a temperature of 40° C. and a relative humidity of 90% measured according to JIS Z0208 (1976). 5 g/m ² /day or less is more preferable, 1.8 g/m ² /day or less is more preferable, and 1.5 g/m ² /day or less is particularly preferable.

(Oxygen barrier property)
The laminated film of the present invention has an oxygen transmission rate (OTR) of 2.7 cc/m ² /day/atm or less under conditions of 25° C. and 80% relative humidity measured according to JIS K7126-2 (2006). is preferred, 2.6 cc/m ² /day/atm or less is more preferred, and 2.5 cc/m ² /day/atm or less is even more preferred.

<< package >>
The laminated film of the present invention can be laminated with another film to produce a package.
Examples of the other films include polyolefin films, polyamide films, polyester films, acrylic films, and the like, which can be laminated by a known method such as dry lamination.

The form of the package is not particularly limited, but includes bags, tubes, lids, bottoms, etc., and can be used for packaging containing foods, pharmaceuticals, electronic parts, industrial parts, etc. Since permeation of oxygen gas and the like can be suppressed, it is possible to prevent corrosion and putrefaction of the contents and enable long-term storage.

<Explanation of terms>
In the present invention, the term "film" encompasses thick sheets to thin films.
In addition, when described as “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, “X or more and Y or less”, “preferably larger than X” and “preferably smaller than Y” ” is included.
Furthermore, when "X or more" (X is an arbitrary number) is described, unless otherwise specified, it includes the meaning of "preferably greater than X", and is described as "Y or less" (Y is an arbitrary number). If so, it also includes the meaning of "preferably smaller than Y" unless otherwise specified.

EXAMPLES The present invention will be described below using Examples, but the present invention is not limited to these.

<Raw materials>
Using the following raw materials, laminated films of Examples and Comparative Examples were produced.

(Base film)
85.7 parts by weight of 2,5-furandicarboxylic acid and 68.2 parts by weight of ethylene glycol were charged as raw materials into a reaction vessel equipped with a stirring device, a nitrogen inlet, a heating device, a thermometer and a pressure reduction port. The inside was made into a nitrogen atmosphere.
Next, the reaction vessel was put into an oil bath, stirring was started, the temperature was raised to 210° C., reaction was performed at 210° C. for 1 hour, and the distillate was recovered. When the reaction liquid became transparent, 0.71 parts by weight of an ethylene glycol solution in which 5% by weight of tetrabutyl titanate was previously dissolved was added.
Subsequently, the temperature was raised to 260° C. over 1 hour and 30 minutes, and the pressure was gradually reduced to about 130 Pa. After 3 hours from the start of depressurization, stirring was stopped and the pressure was restored to complete the polycondensation reaction and obtain a PEF resin.

(Preparation of base film thickness 23 μm)
The obtained PEF-based resin was supplied to an extruder as a raw material, heated and melted at 280° C., extruded onto a cooling roll set at 45° C., cooled and solidified to obtain an unstretched sheet. Next, after stretching 5.0 times in the longitudinal direction at a film temperature of 100 ° C. using the roll peripheral speed difference, it is guided to a tenter, stretched 4.5 times in the horizontal direction at 120 ° C., and heat-treated at 200 ° C. for 10 seconds. After that, it was relaxed 3% in the transverse direction to obtain a PEF base film with a thickness of 23 μm.
The storage modulus (E') at 130°C in the dynamic viscoelasticity measurement of the obtained PEF base film was 230 MPa, and the peak temperature of the loss tangent (tan δ) in the dynamic viscoelasticity measurement was 112°C. .

(Preparation of base film thickness 50 μm)
The obtained PEF-based resin was supplied to an extruder as a raw material, heated and melted at 280° C., extruded onto a cooling roll set at 45° C., cooled and solidified to obtain an unstretched sheet. Next, after stretching 4.5 times in the longitudinal direction at a film temperature of 100 ° C. using the roll peripheral speed difference, it is guided to a tenter, stretched 4.3 times in the horizontal direction at 120 ° C., and heat-treated at 200 ° C. for 10 seconds. After that, it was relaxed 3% in the transverse direction to obtain a PEF base film with a thickness of 50 μm.
The storage modulus (E') at 130°C in the dynamic viscoelasticity measurement of the obtained PEF base film was 180 MPa, and the peak temperature of the loss tangent (tan δ) in the dynamic viscoelasticity measurement was 108°C. .

(Raw material for intermediate resin layer (A))
An isocyanate compound ("Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd.) and a saturated polyester ("Vylon 300" manufactured by Toyobo Co., Ltd.) were blended at a 1:1 mass ratio to obtain a coating liquid used for the intermediate resin layer (A). .

(Inorganic layer (B) raw material)
SiO (manufactured by Canon Optron Co., Ltd.) was used as a raw material for the inorganic layer (B).

(raw material for surface resin layer (C))
An aqueous dispersion of polyurethane resin (C) was prepared as follows. 439.1 g of hydrogenated XDI (1,4-bis(isocyanatomethyl)cyclohexane), 35.4 g of dimethylolpropionic acid, 61.5 g of ethylene glycol, and 140 g of acetonitrile as a solvent were mixed, and the mixture was heated at 70° C. for 3 hours under a nitrogen atmosphere. The reaction was carried out to obtain a carboxyl group-containing polyurethane prepolymer solution. Then, this carboxyl group-containing polyurethane prepolymer solution was neutralized at 50° C. with 24.0 g of triethylamine. 267.9 g of this polyurethane prepolymer solution was dispersed in 750 g of water using a homodisper, chain extension reaction was performed with 35.7 g of 2-[(2-aminoethyl)amino]ethanol, and acetonitrile was distilled off. A polyurethane-based resin having a solid content of 25% by mass was used to obtain a coating liquid to be used for the surface resin layer (C).

<Example 1>
A substrate film having a thickness of 23 μm was corona-treated on one side, and the wetting index of the corona-treated side was adjusted to 40 or more. A coating liquid for the intermediate resin layer (A) was applied to the corona-treated surface by a bar coating method and dried at 80° C. for 1 minute to form an intermediate resin layer (A) having a thickness of 0.03 μm after drying. Next, using a vacuum heating vapor deposition apparatus, a 30 nm thick inorganic layer (B) made of silicon oxide SiOx (x=1.5) is formed under the condition of a degree of vacuum of 2×10 ⁻³ Pa to form a laminate film. (sample film) was obtained.

<Example 2>
A laminate film (sample film) was obtained in the same manner as in Example 1, except that a base film having a thickness of 50 μm was used.

<Example 3>
On the inorganic layer (B) of the laminated film formed in Example 2, the coating liquid for the surface resin layer (C) was further applied by a bar coating method and dried at 80° C. for 1 minute. A laminated film (sample film) was obtained by forming a surface resin layer (C) of 5 μm.

<Comparative Example 1>
A base film having a thickness of 23 μm was used as a sample film of Comparative Example 1 as it was.

<Comparative Example 2>
A base film having a thickness of 50 μm was used as a sample film of Comparative Example 2 as it was.

<Comparative Example 3>
A laminated film (sample film) was prepared in the same manner as in Example 2, except that the inorganic layer (B) was formed on the corona-treated surface of the base film without forming the intermediate resin layer (A). Obtained.

<Evaluation>
The sample films obtained in Examples and Comparative Examples were evaluated as follows, and the results are shown in Table 1.

(Thickness of intermediate resin layer (A))
The surface of the intermediate resin layer (A) was dyed with RuO ₄ and embedded in epoxy resin. After that, the section prepared by the ultra-thin section method is again stained with RuO ₄ , and the intermediate resin layer (A) cross section is measured using TEM ("H-7650" manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100 kV). The thickness of layer (A) was measured.

(Thickness of inorganic layer (B))
The thickness of the inorganic layer (B) was measured using fluorescent X-rays. This method utilizes the phenomenon that when an atom is irradiated with X-rays, it emits fluorescent X-rays peculiar to that atom. can be done. Specifically, thin films with two known thicknesses were formed on the film, the intensity of specific fluorescent X-rays emitted from each was measured, and a calibration curve was created from this information. Then, the fluorescent X-ray intensity was similarly measured for the measurement sample, and the film thickness was measured from the calibration curve.

(dynamic viscoelasticity measurement)
A sheet having a thickness of 200 μm was produced from the PEF resin, which is the main component resin of the base film. Also, the coating liquid used for forming the inorganic layer (B) was dried at 80° C. to prepare a sheet having a thickness of 200 μm.
The viscoelasticity of the sheet is measured using a dynamic viscoelasticity measuring device "DVA-200" manufactured by IT Keisoku Co., Ltd. under the conditions of a frequency of 1 Hz, a temperature increase rate of 3 ° C./min, and a measurement temperature of -50 to 200 ° C. was carried out to determine the peak temperature of storage modulus and loss tangent (tan δ) at 120°C.

(Water vapor barrier property: water vapor transmission rate)
According to JIS Z0208 (1976), using a water vapor transmission rate measuring device (DELTAPERM manufactured by Technolox), the sample films obtained in Examples and Comparative Examples were measured for water vapor transmission rate ( It was evaluated by measuring WVTR (unit: g/m ² /day).
If the water vapor transmission rate is 3.0 g/m ² /day or less, it can be judged that ^the water vapor barrier property is good. evaluated.

(Oxygen barrier property: oxygen permeability)
According to JIS K7126-2 (2006), using an oxygen permeability measuring device (OX-TRAN2/21 type manufactured by MOCON), the sample films obtained in Examples and Comparative Examples were measured at 25 ° C. and 80% relative humidity. It was evaluated by measuring the oxygen transmission rate (OTR, unit: cc/m ² /day/atm) under the following conditions.
If the oxygen permeability is 2.7 cc/m ² /day/atm or less, it can be judged that the oxygen barrier property is good, so it is evaluated as “◯” and exceeds 2.7 cc/m ² /day/atm. In the case, it was evaluated as "x".

(Interlayer strength between base film and inorganic layer (B): peel strength)
The sample films obtained in Examples and Comparative Examples are cut into strips with a width of 15 mm, one end is partially peeled off, and the sample film and unstretched polypropylene film are subjected to a tensile tester (STA-1150 manufactured by Orientec). and peeled off under the conditions of a test speed of 300 mm/min and a peel angle of 180 degrees, and the peel strength (unit: g/15 mm) was measured.
Similarly, the obtained sample film was cut into strips with a width of 15 mm, retort treatment (temperature: 125 ° C., time: 30 minutes) was performed, and then the same operation as above was performed, and retort treatment (125 ° C. hot water The peel strength (unit: g/15 mm) after immersion in the water for 30 minutes) was measured.
If it is 50 g / 15 mm or more under any test condition and is less than 200 g / 15 mm under any one test condition, it is evaluated as "○", and if it is 200 g / 15 mm or more under any test condition, it is evaluated as "◎". If it was less than 50 g/15 mm under any test condition, it was evaluated as "x".

(Discussion)
From the results of the above Examples and Comparative Examples and the results of the tests conducted by the present inventors, it was found that in a laminated film having an inorganic layer on at least one side of the front and back sides of a base film using a furan-based polyester resin, , when the base film is a film containing a polyester resin containing furandicarboxylic acid as a dicarboxylic acid component and ethylene glycol as a diol component, an intermediate resin layer is provided between the base film and the inorganic layer (B) It was found that by providing (A), the adhesion to the inorganic layer can be maintained even under heating conditions such as retort processing, and high gas barrier properties can be exhibited even under high humidity. .

Claims (11)

An intermediate resin layer (A) and an inorganic layer (B) are sequentially laminated on at least one side of the base film,
The laminated film, wherein the base film is a film containing a polyester resin containing furandicarboxylic acid as a dicarboxylic acid component and ethylene glycol as a diol component. The laminated film according to claim 1, wherein the intermediate resin layer (A) contains one or more resins selected from the group consisting of polyester resins, urethane resins and acrylic resins. The laminated film according to claim 2, wherein the intermediate resin layer (A) further contains an isocyanate compound. The laminated film according to any one of claims 1 to 3, wherein the inorganic layer (B) contains one or more inorganic materials selected from the group consisting of silicon oxide, silicon nitride and aluminum oxide. The laminated film according to any one of claims 1 to 4, wherein the base film has a thickness of 5 µm or more and 1000 µm or less. The laminated film according to any one of claims 1 to 5, wherein the intermediate resin layer (A) has a thickness of 5 nm or more and 5000 nm or less. The laminated film according to any one of claims 1 to 6, wherein the inorganic layer (B) has a thickness of 5 nm or more and 200 nm or less. The laminated film according to any one of claims 1 to 7, further comprising a surface resin layer (C) on the surface of the inorganic layer (B). The laminate according to any one of claims 1 to 8, which has a water vapor transmission rate of 3.0 g/m ² /day or less at a temperature of 40°C and a relative humidity of 90% measured according to JIS Z0208 (1976). the film. Any one of claims 1 to 9, wherein the oxygen transmission rate is 2.7 cc/m ² /day/atm or less under conditions of 25°C and 80% relative humidity measured according to JIS K7126-2 (2006). The laminated film according to the item. A package using the laminated film according to any one of claims 1 to 10.