JP7815801B2 - Laminated Film - Google Patents

Description

The present invention relates to a laminated film.

When packaging metallic contents such as medical devices, industrial materials, and electronic components, the contents must be dried before packaging to prevent rust and other problems from forming on the contents. If the contents are not completely dry, they must be dried after packaging, but to do this, the film used to package the contents must be moisture-permeable.

Highly moisture-permeable base films have been known in the past (for example, Patent Document 1). However, these conventional highly moisture-permeable base films cannot ensure gas barrier properties, and there is a risk of the contents deteriorating due to oxidation. Furthermore, to prevent the contents from deteriorating, it is necessary to seal in an inert gas such as carbon dioxide or nitrogen. However, conventional highly moisture-permeable base films also allow inert gases to pass through, making it impossible to seal in the inert gas, and making it difficult to prevent the packaged contents from deteriorating.

Furthermore, if the film has low water resistance, there is a risk that the film will melt and contaminate the contents if the contents contain water or if hot moisture is attached to the film, or that the film's gas barrier properties will be reduced. Furthermore, if water gets on the outside of the packaging, the film may melt and its gas barrier properties may be reduced.

Japanese Patent Application Laid-Open No. 2019-163357

The present invention was made in consideration of the above circumstances, and aims to provide a laminated film that has excellent moisture permeability and gas barrier properties, as well as excellent water resistance.

To achieve the above objectives, the present invention adopts the following configuration.

[1] A laminate film comprising a base layer and a coating layer provided on one surface of the base layer, wherein the water vapor transmission rate of the laminate film measured by the cup method specified in JIS Z 0208 at 30°C and 97% RH is 4000 g/ ^m2 ·day or more, and the air resistance of the laminate film measured by the Oken method specified in JIS P 8117:2009 at 23°C and 50% RH is 5000 seconds or more, the water vapor transmission rate of the laminate film after a hot water treatment in which the laminate film is immersed in hot water at 95°C for 18 hours and dried at 100°C is 75 to 125% of the water vapor transmission rate of the laminate film before the hot water treatment, and the mass of the coating layer after the hot water treatment is 55 to 100% of the mass of the coating layer before the hot water treatment.
[2] The laminate film according to [1], wherein the mass of the coating layer after a water treatment in which the laminate film is immersed in water at 25°C for 18 hours and dried at 100°C is 90 to 100% of the mass of the coating layer before the water treatment.
[3] The laminated film according to [1] or [2], wherein the thickness of the coating layer is 0.1 μm or more and 5.0 μm or less.
[4] The laminated film according to any one of [1] to [3], wherein the coating layer has a crosslinked structure.
[5] The laminate film according to [4], wherein the coating layer comprises a single layer containing a crosslinked resin in which at least one selected from the group consisting of saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, polyether, and polyurethane is crosslinked.

The laminated film of the present invention is a laminated film comprising a substrate layer and a coating layer provided on one surface of the substrate layer, wherein the water vapor permeation amount of the laminated film measured by the cup method specified in JIS Z 0208 under conditions of 30°C and 97% RH is 4000 g/ ^m2 ·day or more, and the water vapor permeation amount of the laminated film measured by the cup method specified in JIS P The laminated film has an air resistance of 5,000 seconds or more at 23°C and 50% RH, as measured by the Oken method specified in JIS K 8117:2009; the laminated film has a water vapor permeation rate of 75 to 125% of the water vapor permeation rate of the laminated film before the hot water treatment, in which the laminated film is immersed in hot water at 95°C for 18 hours and then dried at 100°C; and the mass of the coating layer after the hot water treatment is 55 to 100% of the mass of the coating layer before the hot water treatment. Therefore, the laminated film has excellent moisture permeability and gas barrier properties, as well as excellent water resistance.

1 is a cross-sectional view showing the configuration of a laminated film according to one embodiment of the present invention.

<<Laminated film>>
The laminate film of the present embodiment is a laminate film including a base layer and a coating layer provided on one surface of the base layer, and has excellent moisture permeability because the water vapor transmission rate of the laminate film measured by the cup method specified in JIS Z 0208 at 30°C and 97% RH is 4000 g/ ^m2 ·day or more.
Furthermore, the laminate film of the present embodiment has an air permeability resistance of 5000 seconds or more at 23°C and 50% RH, measured by the Oken method specified in JIS P 8117:2009, and therefore has excellent gas barrier properties.

Furthermore, the laminate film of this embodiment has excellent water resistance because the water vapor permeability of the laminate film after hot water treatment, in which the film is immersed in hot water at 95°C for 18 hours and then dried at 100°C, is 75 to 125% of the water vapor permeability of the laminate film before the hot water treatment, and the mass of the coating layer after the hot water treatment is 55 to 100% of the mass of the coating layer before the hot water treatment.

Furthermore, in the laminate film of this embodiment, it is preferable that the mass of the coating layer after water treatment, in which the laminate film is immersed in water at 25°C for 18 hours and then dried at 100°C, is 90 to 100% of the mass of the coating layer before the water treatment, as this further improves water resistance.

The laminate film of this embodiment has excellent moisture permeability, so even if the contents are packaged without being completely dried, they can be dried after packaging. Furthermore, because the laminate film of this embodiment has excellent gas barrier properties, deterioration of the contents can be prevented by sealing in an inert gas after packaging. Therefore, for example, metal items such as medical devices, industrial materials, and electronic components can be packaged without being dried, and by sealing in an inert gas after packaging, they can be dried after packaging, allowing packaging to be completed in a short time and preventing deterioration due to rust and other factors. Furthermore, because the laminate film of this embodiment has excellent water resistance, even if the contents contain water, the film can be prevented from dissolving and contaminating the contents, and the gas barrier properties of the film can be prevented from being reduced.

First, the overall structure of the laminated film of the present invention will be described.
Fig. 1 is a cross-sectional view schematically illustrating one embodiment of the laminated film of the present invention. In the drawings used in the following description, for the sake of convenience, essential parts may be shown enlarged in order to make the features of the present invention easier to understand, and the dimensional ratios of the respective components may not necessarily be the same as those in reality.

The laminated film 1 of this embodiment is generally composed of a substrate layer 3 and a coating layer 2 provided on one side of the substrate layer 3. The laminated film 1 of this embodiment can be used as a packaging film, particularly for packaging metal items such as medical devices, industrial materials, and electronic components.

<Base material layer>
The substrate layer (also referred to as core layer) 3 can impart flexibility to the laminate film 1. Resins that can be used for the substrate layer 3 are not particularly limited as long as they are capable of imparting the above-mentioned functions and have moisture permeability, and examples thereof include polyolefin resins, polyester resins, nylon resins, ethylene-vinyl acetate copolymers, olefin elastomers, etc. The substrate layer may or may not be porous as long as it has moisture permeability.

Examples of polyolefin resins include polyethylene copolymers, polypropylene copolymers, and butene copolymers, and among these, polyethylene copolymers and polypropylene copolymers are preferred.
From the viewpoint of improving adhesiveness, the copolymer may be in the form of a random copolymer, a graft copolymer, a block copolymer or a graft copolymer, with a random copolymer being particularly preferred.

The polyolefin resin is an olefin copolymer.
The polyethylene copolymer is a copolymer of ethylene and a monomer other than ethylene.
The polypropylene copolymer is a copolymer of propylene and a monomer other than propylene.
The butene copolymer is a copolymer of butene and a monomer other than butene.

Polyethylene copolymers include, but are not limited to, copolymers of ethylene and vinyl group-containing monomers.

Examples of copolymers of ethylene and vinyl group-containing monomers include maleic anhydride-grafted linear low-density polyethylene (hereinafter referred to as "LLDPE-g-MAH"), ethylene-vinyl acetate copolymer (hereinafter referred to as "EVA resin"), ethylene-methyl methacrylate copolymer (hereinafter referred to as "EMMA resin"), ethylene-ethyl acrylate copolymer (hereinafter referred to as "EEA resin"), ethylene-methyl acrylate copolymer (hereinafter referred to as "EMA resin"), ethylene-ethyl acrylate-maleic anhydride copolymer (hereinafter referred to as "E-EA-MAH resin"), ethylene-acrylic acid copolymer (hereinafter referred to as "EAA resin"), ethylene-methacrylic acid copolymer (hereinafter referred to as "EMAA resin"), ionomer (hereinafter referred to as "ION resin"), and ethylene-based thermoplastic elastomer. In this specification, ION resin refers to a copolymer of ethylene and a small amount of acrylic acid or methacrylic acid, which has an ionically crosslinked structure formed by salt formation between the acid moiety and metal ions.

Specific examples of polyester resins include polyethylene terephthalate resin, polytrimethylene terephthalate resin, polytetramethylene terephthalate resin, and polyhexamethylene terephthalate resin.

Examples of nylon resins include 4-nylon, 6-nylon, 7-nylon, 11-nylon, 12-nylon, 46-nylon, 66-nylon, 69-nylon, 610-nylon, 611-nylon, 612-nylon, 6T-nylon, 6I-nylon, copolymer of 6-nylon and 66-nylon (nylon 6/66), copolymer of 6-nylon and 610-nylon, copolymer of 6-nylon and 611-nylon, copolymer of 6-nylon and 12-nylon (nylon 6/12), copolymer of 6-nylon and 612-nylon, 6-nylon Examples of such nylon include copolymers of nylon and 6T-nylon, copolymers of nylon 6 and 6I-nylon, copolymers of nylon 6, 66-nylon and 610-nylon, copolymers of nylon 6, 66-nylon and 12-nylon (nylon 6/66/12), copolymers of nylon 6, 66-nylon and 612-nylon, copolymers of nylon 66 and 6T-nylon, copolymers of nylon 66 and 6I-nylon, copolymers of nylon 6T-nylon and 6I-nylon, copolymers of nylon 66, 6T-nylon and 6I-nylon, and amorphous nylon. Among these, from the standpoints of heat resistance, mechanical strength, and ease of availability, 6-nylon, 12-nylon, 66-nylon, nylon 6/66, nylon 6/12, and nylon 6/66/12 are preferred, with 6-nylon being more preferred.

The base material layer 3 may consist of a single layer, or two or more layers. For example, by making the base material layer 3 out of multiple layers made of different materials, it is possible to adjust the properties of the base material layer 3, such as its hardness and moisture permeability.

The thickness ratio of the base layer 3 to the total thickness of the laminate film 1 is preferably 75 to 99.9%, more preferably 90 to 99.9%, even more preferably 95 to 99.9%, and particularly preferably 97 to 99.5%. When this thickness ratio is equal to or greater than the lower limit, flexibility can be imparted to the laminate film 1. When this thickness ratio is equal to or less than the upper limit, a decrease in moisture permeability when a resin film is laminated is suppressed.

The thickness of the substrate layer 3 is preferably 10 to 100 μm, and more preferably 15 to 50 μm. If the thickness is at or above the lower limit of the preferred range, the decrease in moisture permeability when a resin film is laminated is suppressed, and if the thickness is at or below the upper limit, flexibility is achieved.

The water vapor permeability of the substrate layer 3 at 30°C and 97% RH, measured by the cup method specified in JIS Z 0208, is preferably 4000 g/ ^m2 ·day or more, more preferably 5000 g/ ^m2 ·day or more, and even more preferably 6000 g/ ^m2 ·day or more, and may be, for example, 7000 g/ ^m2 ·day or more. The water vapor permeability can be adjusted by the type, thickness, porosity, pore size, etc. of the substrate layer 3.
Furthermore, the water vapor transmission rate of the base layer 3 at 30°C and 97% RH, measured by the cup method specified in JIS Z 0208, is preferably 20,000 g/ ^m2 ·day or less, and more preferably 15,000 g/ ^m2 ·day or less. When the water vapor transmission rate is equal to or less than the upper limit, it is possible to prevent external moisture (humidity) from penetrating the base layer 3 and affecting the inside of the laminate film when the outside of the laminate film is highly humid.

<Coating layer>
The coating layer is a resin layer that suppresses gas permeation and is provided to impart gas barrier properties to the base layer. The type of gas is not particularly limited as long as it does not affect the contents packaged in the laminated film, and examples thereof include carbon dioxide and nitrogen.

[Gas barrier resin]
The coating layer contains a gas barrier resin.
The gas barrier resin is a resin that suppresses gas permeation and imparts gas barrier properties to the base layer. The type of gas is not particularly limited as long as it does not affect the contents packaged in the laminate film described below, and examples thereof include carbon dioxide and nitrogen.

The coating layer preferably has a crosslinked structure to impart water resistance. That is, the coating layer preferably contains a resin with a crosslinked structure (sometimes referred to herein as a "crosslinked gas barrier resin") as the gas barrier resin. The crosslinked structure (crosslinked gas barrier resin) can be formed by reacting a gas barrier resin without a crosslinked structure (sometimes referred to herein as an "uncrosslinked gas barrier resin") with a crosslinking agent.

(Uncrosslinked gas barrier resin)
The uncrosslinked gas barrier resin is preferably one that can impart gas barrier properties to the base layer and prevent a decrease in the moisture permeability of the base layer. Specific examples include saponified ethylene vinyl acetate copolymer, polyvinyl alcohol, modified polyvinyl alcohol in which polyvinyl alcohol is partially modified, hydroxyethyl cellulose, polyether, polyurethane, polyamide, cellophane, cellulose, polysaccharides such as starch, and polyhydroxyethyl (meth)acrylate.

Examples of modified polyvinyl alcohol include cationically modified polyvinyl alcohol, anionically modified polyvinyl alcohol, nonionically modified polyvinyl alcohol, and vinyl alcohol polymers. Modified polyvinyl alcohols also include vinyl acetate resins (e.g., "Exceval" manufactured by Kuraray Co., Ltd.), polyvinyl acetal resins obtained by reacting polyvinyl alcohol with aldehyde (e.g., "S-LEC" manufactured by Sekisui Chemical Co., Ltd.), silanol-modified polyvinyl alcohols containing silanol groups (e.g., "R-1130" manufactured by Kuraray Co., Ltd.), and modified polyvinyl alcohol resins containing acetoacetyl groups in the molecule (e.g., "GOHSEFIMER® Z/WR series" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

Examples of anion-modified polyvinyl alcohol include polyvinyl alcohol with anionic groups, such as those described in JP-A-1-206088, copolymers of vinyl alcohol and vinyl compounds with water-soluble groups, such as those described in JP-A-61-237681 and JP-A-63-307979, and modified polyvinyl alcohol with water-soluble groups, such as those described in JP-A-7-285265.

Other examples of nonion-modified polyvinyl alcohol include polyvinyl alcohol derivatives in which polyalkylene oxide groups are added to a portion of vinyl alcohol, as described in JP-A-7-9758 (e.g., "GOHSENEX (registered trademark) WO" manufactured by Mitsubishi Chemical Corporation), block copolymers of vinyl alcohol and a vinyl compound having a hydrophobic group, as described in JP-A-8-25795, silanol-modified polyvinyl alcohol having a silanol group, and reactive group-modified polyvinyl alcohol having a reactive group such as an acetoacetyl group, a carbonyl group, or a carboxy group (e.g., "D Polymer" manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., which is a reactive group-modified polyvinyl alcohol having a carbonyl group).

Cation-modified polyvinyl alcohols include, for example, polyvinyl alcohols having primary, secondary, or tertiary amino groups or quaternary ammonium groups in the main chain or side chain of the polyvinyl alcohol, as described in JP-A-61-10483, which are obtained by saponifying a copolymer of vinyl acetate and an ethylenically unsaturated monomer having a cationic group.

Examples of vinyl alcohol polymers include Exeval (mentioned above) and Nichigo G Polymer (product name: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

Examples of polyethers include polyoxymethylene, chlorinated polyethers, glycol condensates (polyethylene glycol (polyethylene oxide), polypropylene glycol, and copolymer compositions thereof, etc.), and polyethers containing aromatic rings (polyphenylene oxide, polysulfone, etc.).
Among these, glycol condensates are preferred because of their effect of increasing moisture permeability. Examples of components that form glycol condensates include ethylene glycol (the number of carbon atoms between ether bonds in the polymer chain is 2), propylene glycol (the number of carbon atoms between ether bonds in the polymer chain is 3), butylene glycol (the number of carbon atoms between ether bonds in the polymer chain is 4), and derivatives thereof. To achieve high moisture permeability, the number of carbon atoms is preferably 4 or less, more preferably 3 or less, and particularly preferably 2.2 or less. To suppress the moisture absorption of the gas barrier film after film formation and to achieve excellent shape retention, the number of carbon atoms between ether bonds in the polymer chain is preferably 2.01 or more, more preferably 2.05 or more. Here, the number of carbon atoms between ether bonds in the polymer chain refers to an average value calculated from the number of carbon atoms in each repeating unit that forms the polymer and the number of repeating units.
Examples of polyethers include Alcox (trade name: manufactured by Meisei Chemical Industry Co., Ltd.).

Examples of polyurethanes include polyester-based, polycarbonate-based, and polyether-based polyurethanes. In this specification, "polyester-based polyurethane" means "polyurethane having a polyester segment.""Polycarbonate-basedpolyurethane" means "polyurethane having a polycarbonate segment.""Polyether-basedpolyurethane" means "polyurethane having a polyether segment."
In terms of the effect of increasing moisture permeability, polyether polyurethanes having highly hydrophilic polyether segments in the molecular chain are preferred. Specifically, those having polyether segments such as polyoxyethylene glycol or a block copolymer of polyoxyethylene and polyoxypropylene, and having a long length between urethane bonds, are preferred. In addition, to improve moisture permeability, the Tg of the polyurethane is preferably 25°C or less, more preferably -20°C or less, and particularly preferably -50°C or less.
Alternatively, a varnish in which polyurethane is dispersed may be used as the polyurethane. Examples of varnishes include organic solvent solution types and water dispersion types. The use of water dispersion types is preferred in terms of not damaging the environment and being effective in suppressing penetration and erosion of the substrate and anchor coat layer. Examples of varnishes in which polyurethane is dispersed include Hydran (trade name: manufactured by DIC Corporation).

Among these, uncrosslinked gas barrier resins, particularly saponified ethylene vinyl acetate copolymers, resins containing hydrophilic groups such as polyvinyl alcohol, modified polyvinyl alcohol, and hydroxyethyl cellulose, as well as polyethers and polyurethanes, are preferred because they are highly effective in preventing a decrease in the moisture permeability of the base layer.

The moisture permeability and gas barrier properties of polyvinyl alcohol or modified polyvinyl alcohol can be adjusted by adjusting the molecular weight and degree of saponification. The degree of saponification of polyvinyl alcohol or modified polyvinyl alcohol is preferably 70 to 99 mol%, more preferably 85 to 99 mol% or more, and even more preferably 97 to 99 mol% or more. If the degree of saponification is equal to or higher than the lower limit, the coating layer has increased water resistance and is less likely to dissolve even when in contact with water. Furthermore, if the degree of saponification is equal to or lower than the upper limit, water solubility is maintained at an appropriate level, making it possible to prepare a solution with good coatability.
The viscosity of a 4% by mass solution of polyvinyl alcohol or modified polyvinyl alcohol is preferably 3 mPa s or more, more preferably 8.0 mPa s or more, and even more preferably 20 mPa s or more. When the 4% by mass solution of polyvinyl alcohol or modified polyvinyl alcohol has the above viscosity, the coating layer has high water vapor permeability, increased strength, and low moisture absorption.
From the viewpoint of the coatability of the solution, the viscosity of a 4% by mass solution is preferably 1000 mPa·s or less.

The resin film may contain only one type of uncrosslinked gas barrier resin, or two or more types. If two or more types are used, the combination and ratio of these resins can be selected as desired depending on the purpose.

The coating layer may contain an uncrosslinked gas barrier resin.

The resin film may contain only one type of uncrosslinked gas barrier resin, or two or more types. If two or more types are used, the combination and ratio of these resins can be selected as desired depending on the purpose.

(Crosslinking agent)
Examples of crosslinking agents include titanium compounds, metal chelate compounds, boron compounds, isocyanate compounds, organic acids, acid-modified polymers, hydrazide compounds, alkylamines, and azo compounds. Examples of titanium compounds include alkoxide titanium compounds and acylate titanium compounds. Examples of hydrazide compounds include adipic acid dihydrazide, sebacic acid dihydrazide, dodecanediohydrazide, isophthalic acid dihydrazide, and salicylic acid hydrazide. Examples of metal chelate compounds include zirconium compounds (e.g., "Zircosol AC-7" and "Zircosol ZC-20" manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.). Examples of organic acids include polycarboxylic acids such as malic acid, maleic acid, citric acid, and succinic acid. For example, when the gas barrier resin has a hydroxyl group, the crosslinking agent is preferably a titanium compound, a metal chelate compound, etc., and when the gas barrier resin has a carbonyl group, the crosslinking agent is preferably a compound that forms an amide bond with the carbonyl group, such as a hydrazide compound, an alkylamine, an azo compound, etc. Specific examples of the crosslinking agent include titanium lactate (e.g., "Orgatix TC310" manufactured by Matsumoto Fine Chemical Co., Ltd.), titanium triethanolaminate (e.g., "Orgatix TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.), etc.

The crosslinking agent to be reacted with the uncrosslinked gas barrier resin may be one type only, or two or more types. If two or more types are used, the combination and ratio of these can be selected as desired depending on the purpose.

Examples of cross-linked gas barrier resins include reaction products of at least one uncross-linked gas barrier resin and at least one of the above-mentioned cross-linking agents.

(Cross-linked gas barrier resin)
The resin film may contain only one type of crosslinked gas barrier resin, or two or more types. When two or more types are used, the combination and ratio thereof can be selected arbitrarily depending on the purpose.

When forming a crosslinked gas barrier resin, it is preferable to use, for example, a polyvinyl alcohol resin as the uncrosslinked gas barrier resin, and a titanium-based crosslinking agent or a hydrazide compound as the crosslinking agent. The amount of crosslinking agent added is preferably 5 to 70% by weight relative to the resin. For example, when a polyvinyl alcohol resin is used as the uncrosslinked gas barrier resin and a titanium-based crosslinking agent is used as the crosslinking agent, the amount of crosslinking agent added is preferably 10 to 70% by weight, and more preferably 30 to 70% by weight. When a modified polyvinyl alcohol is used as the uncrosslinked gas barrier resin and a hydrazide compound is used as the crosslinking agent, the amount of crosslinking agent added is preferably 5 to 20% by weight.

When a crosslinked gas barrier resin is formed by reaction between an uncrosslinked gas barrier resin and a crosslinking agent, the reaction temperature is preferably 70 to 120°C, and more preferably 90 to 110°C.
The reaction time is preferably 0.1 minutes to 2 hours, more preferably 0.2 minutes to 10 minutes, and even more preferably 0.3 minutes to 3 minutes.

It is preferable to use a solvent when reacting the uncrosslinked gas barrier resin with the crosslinking agent.
Examples of the solvent used in the reaction include water, ethanol, 2-propanol, and ethyl acetate.
The solvent used in the reaction may be one kind or two or more kinds. When two or more kinds are used, the combination and ratio thereof can be selected arbitrarily depending on the purpose.
The cross-linkable gas barrier resin after the reaction is preferably dried to remove the solvent. The drying temperature is preferably 90 to 120°C, and the drying time is preferably 0.2 to 10 minutes, and more preferably 1 to 3 minutes.

Preferred examples of crosslinked gas barrier resins include crosslinked resins in which at least one selected from the group consisting of saponified ethylene vinyl acetate copolymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, polyether, polyurethane, polyamide, cellophane, cellulose, starch, and polyhydroxyethyl (meth)acrylate is crosslinked.
More preferred crosslinked gas barrier resins include, for example, crosslinked resins in which at least one selected from the group consisting of saponified ethylene vinyl acetate copolymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, polyether, and polyurethane is crosslinked.

The coating layer may contain only the gas barrier resin (in other words, only cross-linked gas barrier resin, or only cross-linked gas barrier resin and uncross-linked gas barrier resin) (i.e., it may consist of a gas barrier resin), or it may contain other components that do not fall under the category of gas barrier resin (i.e., it may consist of the gas barrier resin and the other components).

(Other ingredients)
Examples of the other components include additives known in the art.
In addition to the crosslinking agent, the additives include, for example, antifogging agents, antiblocking agents, antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, organic particles, inorganic fibers, organic fibers, viscosity reducers, thickeners, heat stabilizers, lubricants, infrared absorbers, and ultraviolet absorbers. Antifogging agents are preferably used because they can improve moisture permeability by making the resin film surface more compatible with water. Examples of antifogging agents include glycerin laurate, diglycerin laurate, decaglycerin laurate, glycerin monostearate, and sorbitan stearate. Inorganic and organic fibers can improve the film strength and water resistance. Examples of organic fibers include cellulose, and cellulose nanofibers (CNF) are preferably used.

The coating layer may contain only one type of other component, or two or more types. If there are two or more types, the combination and ratio of these components can be selected as desired depending on the purpose.

In the coating layer, the content ratio of the gas barrier resin to the total mass of the coating layer may be set to a different range in addition to the above-mentioned range, depending on the application of the laminate film.

The coating layer may consist of one layer (single layer), or two or more layers. When the coating layer consists of multiple layers, these layers may be the same or different, and there are no particular restrictions on the combination of these layers as long as it does not impair the effects of the present invention.

The thickness of the coating layer is not particularly limited, but is preferably 0.1 μm or more and 5.0 μm or less, more preferably 0.3 μm or more and 4.0 μm or less, and may be any of 0.4 μm or more and 3.0 μm or less, and 0.4 μm or more and 2.0 μm or less. When the thickness of the coating layer is equal to or more than the lower limit, the effect of imparting gas barrier properties to the substrate layer is improved. When the thickness of the coating layer is equal to or less than the upper limit, the decrease in moisture permeability of the substrate layer can be further suppressed.
Here, the "thickness of the coating layer" means the thickness of the entire coating layer, and for example, the thickness of a coating layer consisting of multiple layers means the total thickness of all layers that make up the coating layer.

The water vapor permeation rate of the laminated film measured by the cup method specified in JIS Z 0208 under conditions of 30°C and 97% RH is 4000 g/ ^m2 ·day or more, preferably 4500 g/ ^m2 ·day or more, more preferably 5000 g/ ^m2 ·day or more, and may be, for example, 6000 g/ ^m2 ·day or more. The water vapor permeation rate can be adjusted by the type, thickness, porosity, pore size, etc. of the substrate layer, or the type or content of a component contained in the coating layer, or the thickness of the coating layer.
Furthermore, the water vapor transmission rate of the laminated film at 30°C and 97% RH, measured by the cup method specified in JIS Z 0208, is preferably 20,000 g/ ^m2 ·day or less, and more preferably 15,000 g/ ^m2 ·day or less. When the water vapor transmission rate is equal to or less than the upper limit, it is possible to prevent external moisture (humidity) from penetrating the film and affecting the inside of the film when the outside of the film is highly humid.

The air permeability resistance of the laminated film measured by the Oken method specified in JIS P 8117:2009 under conditions of 23°C and 50% RH is 5,000 seconds or more, preferably 10,000 seconds or more, more preferably 50,000 seconds or more, and may be any of 100,000 seconds or more and 1,000,000 seconds or more. The air permeability resistance can be adjusted by the type or thickness of the substrate, the type or content of components contained in the coating layer, or the thickness of the coating layer.
The laminated film preferably has an air resistance of 10,000,000 seconds or less at 23°C and 50% RH, as measured by the Oken method specified in JIS P 8117: 2009. When the air resistance is equal to or less than the upper limit, measurement can be performed within the limits of measurement by a measuring device.

The water vapor permeability of the laminate film after hot water treatment, in which the laminate film is immersed in hot water at 95°C for 18 hours and dried at 100°C, is 75 to 125%, preferably 80 to 120%, and more preferably 85 to 115%, of the water vapor permeability of the laminate film before hot water treatment. For example, it may be any of 75 to 120%, 75 to 115%, 80 to 125%, 80 to 115%, 85 to 125%, 85 to 120%, 90 to 125%, 90 to 120%, 90 to 115%, 90 to 110%, 90 to 105%, or 90 to 100%. The ratio (%) of the water vapor permeability of the laminate film after hot water treatment, in which the laminate film is immersed in hot water at 95°C for 18 hours and then dried at 100°C, to the water vapor permeability of the laminate film before hot water treatment, can be adjusted by adjusting the type or content of components contained in the coating layer, or the thickness of the coating layer.

The mass of the coating layer after hot water treatment, in which the laminate film is immersed in hot water at 95°C for 18 hours and dried at 100°C, is 55 to 100%, preferably 60 to 100%, more preferably 65 to 100%, even more preferably 70 to 100%, and particularly preferably 75 to 100%, and may be, for example, 80 to 100% or 90 to 100%. The ratio (%) of the mass of the laminate film after hot water treatment, in which the laminate film is immersed in hot water at 95°C for 18 hours and dried at 100°C, to the mass of the laminate film before hot water treatment, can be adjusted depending on the type or content of components contained in the coating layer, or the thickness of the coating layer.

Furthermore, the mass of the coating layer after the water treatment in which the laminate film is immersed in water at 25°C for 18 hours and dried at 100°C is preferably 90 to 100%, and more preferably 95 to 100%, of the mass of the coating layer before the water treatment. The ratio (%) of the mass of the coating layer after the water treatment in which the laminate film is immersed in water at 25°C for 18 hours and dried at 100°C to the mass of the coating layer before the water treatment can be adjusted depending on the type or content of components contained in the coating layer, or the thickness of the coating layer.

<Method of manufacturing laminated film>
Next, a method for producing the laminated film 1 will be described.
The method for producing the laminated film 1 of this embodiment is not particularly limited, but it can be produced, for example, by applying a coating layer onto one surface of a base layer and laminating the coating layer.

For example, a resin composition containing the gas barrier resin and, if necessary, the other components can be applied to one side of a substrate layer and dried as necessary, thereby forming (laminated) a coating layer on the substrate layer.

The resin composition may contain a solvent in order to improve its applicability for coating.
Examples of the solvent include water, 2-propanol (IPA), ethanol, methanol, methyl ethyl ketone (MEK), ethyl acetate, toluene, and acetone.

The resin composition may contain only one type of solvent, or two or more types. If two or more types are used, the combination and ratio of these solvents can be selected as desired depending on the purpose.

This method of producing the laminated film by coating it with a resin composition is particularly effective when the desired laminated film contains components that decompose, ignite, or vaporize at relatively low temperatures. Examples of such components that are unsuitable for handling at high temperatures include potassium sorbate and sodium lactate.

The resin composition can be applied using a known method. For example, the resin composition can be applied using various coaters.

There are no particular restrictions on the drying conditions for the resin composition, but if the resin composition contains a solvent, as described below, it is preferable to heat-dry it. In this case, it is preferable to dry it at a temperature of, for example, 40 to 120°C.

<<Packaging body and manufacturing method thereof>>
A package can be produced by using the laminated film so that the coating layer is positioned on the packaging object side and packaging the packaging object.
The packaging body includes the laminated film, which allows the contents in the packaging body to be dried after packaging, and by sealing an inert gas in the packaging body, deterioration of the contents can be prevented. Furthermore, even if the contents contain water, the coating layer can be prevented from dissolving and contaminating the contents, and the gas barrier properties of the coating layer can be prevented from being lost or reduced. Therefore, deterioration due to rust, etc., can be prevented for metal articles such as medical devices, industrial materials, and electronic components.

During packaging, for example, the object to be packaged is wrapped in one sheet of the laminate film, and the remaining portion of the laminate film (the portion not wrapping the object to be packaged) is overlapped with another portion of the laminate film and sealed, thereby packaging the object to be packaged. At this time, the coating layer in the laminate film may be overlapped, or the coating layer and the base layer may be overlapped.
In addition, during packaging, for example, the object to be packaged can be sandwiched between two sheets of the laminate film, and these laminate films can be overlapped and sealed to package the object to be packaged. At this time, the coating layers of the laminate films can be overlapped, or the coating layer and the base layer can be overlapped.
Furthermore, the object to be packaged can be packaged by placing the object on a tray and sealing the coating layer in the laminated film with the periphery of the tray.

The effects of the present invention will be explained in detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]
<<Laminated film manufacturing>>
Modified polyvinyl alcohol ("Exceval RS-2117" manufactured by Kuraray Co., Ltd.) (solids concentration: 100% by mass, 4% by mass aqueous solution viscosity at 20°C: 26.5 mPa·s, saponification degree: 97.5-99 mol%) was diluted with a solvent (a 9:1 mixed solvent of water and 2-propanol) to a solids concentration of 2% by mass, and 30 phr (30 parts by mass of Orgatix TC310 per 100 parts by mass of modified polyvinyl alcohol) of a titanium-based crosslinking agent ("Orgatix TC310" manufactured by Matsumoto Fine Chemical Co., Ltd.) (44% titanium lactate, 40% water, 16% isopropanol) of the dilution was mixed. The resulting resin solution was applied to one side of a substrate film ("Microporous Film" manufactured by 3M Co., Ltd., thickness: 30 μm) and dried at 100°C for 2 hours to form a coating layer (thickness: 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Example 2]
<<Laminated film manufacturing>>
A resin solution obtained by mixing a modified polyvinyl alcohol ("Exceval RS-2117" manufactured by Kuraray Co., Ltd.) (solid content: 100% by mass, 4% by mass aqueous solution viscosity at 20°C: 26.5 mPa·s, degree of saponification: 97.5-99 mol%) diluted with a solvent (a 9:1 mixed solvent of water and 2-propanol) to a solid content of 2% by mass, with 30 phr (30 parts by mass of Orgatix TC400 per 100 parts by mass of modified polyvinyl alcohol) of a titanium-based crosslinking agent ("Orgatix TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) (80% titanium triethanolamine, 20% isopropanol) was applied to one side of a substrate film ("Microporous Film" manufactured by 3M Co., Ltd., thickness: 30 μm) and dried at 100°C for 2 minutes to form a coating layer (thickness: 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Example 3]
<<Laminated film manufacturing>>
A resin solution obtained by mixing a modified polyvinyl alcohol ("GOHSENEX WO320N" manufactured by Mitsubishi Chemical Corporation) (solid content: 100% by mass, viscosity of a 4% by mass aqueous solution at 20°C: 6.5 to 8.5 mPa·s, degree of saponification: 97.5 to 99 mol%) diluted with a solvent (water) to a solid content of 2% by mass with 30 phr of a titanium-based crosslinking agent ("ORGATIX TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) (30 parts by mass of ORGATIX TC400 per 100 parts by mass of the modified polyvinyl alcohol) was applied to one side of a substrate film ("Microporous Film" manufactured by 3M Co., Ltd., thickness: 30 μm) and dried at 100°C for 2 minutes to form a coating layer (thickness: 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Example 4]
<<Laminated film manufacturing>>
A coating layer (thickness 1 μm) was formed on a substrate film in the same manner as in Example 3, except that 50 phr of a titanium-based crosslinking agent ("Orgatix TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) was used.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Example 5]
<<Laminated film manufacturing>>
A coating layer (thickness 1 μm) was formed on a substrate film in the same manner as in Example 3, except that 60 phr of a titanium-based crosslinking agent ("Orgatix TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) was used.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Example 6]
<<Laminated film manufacturing>>
A coating layer (thickness 1 μm) was formed on a substrate film in the same manner as in Example 3, except that 70 phr of a titanium-based crosslinking agent ("Orgatix TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) was used.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Example 7]
<<Laminated film manufacturing>>
A coating layer (thickness: 1 μm) was formed on a substrate film in the same manner as in Example 3, except that 30 phr of a titanium-based crosslinking agent ("Orgatix TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) was replaced with 30 phr (30 parts by mass of Orgatix TC400 per 100 parts by mass of modified polyvinyl alcohol) of a titanium-based crosslinking agent ("Orgatix TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) and 20 phr of an organic fiber, cellulose nanofiber ("AuroVisco" manufactured by Oji Holdings Co., Ltd.) as a crosslinking aid (20 parts by mass of AuroVisco per 100 parts by mass of modified polyvinyl alcohol).
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Example 8]
<<Laminated film manufacturing>>
A mixture of 75% by mass of modified polyvinyl alcohol ("GOHSENEX WO320N" manufactured by Mitsubishi Chemical Corporation) (solid content: 2% by mass, viscosity of 4% by mass aqueous solution at 20°C: 6.5 to 8.5 mPa·s, degree of saponification: 97.5 to 99 mol%) and 25% by mass of hydroxyethyl cellulose ("HEC AG-15F" manufactured by Sumitomo Seika Chemicals Co., Ltd.) (solid content: 100% by mass, viscosity of 2% by mass aqueous solution at 20°C: 200 to 300 mPa·s) diluted with a solvent (water) to a solid content of 2% by mass, and 60 phr (100 parts by mass of modified polyvinyl alcohol per 100 parts by mass of modified polyvinyl alcohol) of a titanium-based crosslinking agent ("ORGATIX TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) was used. The resin solution obtained by mixing the above-mentioned acrylic resin and acrylic resin (60 parts by mass) was applied to one side of a substrate film ("Microporous Film" manufactured by 3M, thickness 30 μm) and dried at 100°C for 2 minutes to form a coating layer (thickness 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Example 9]
<<Laminated film manufacturing>>
A mixture of 75% by mass of modified polyvinyl alcohol ("GOHSENEX WO320N" manufactured by Mitsubishi Chemical Corporation) (solid content: 2% by mass, viscosity of 4% by mass aqueous solution at 20°C: 6.5 to 8.5 mPa·s, degree of saponification: 97.5 to 99 mol%) and 25% by mass of hydroxyethyl cellulose ("HEC AV-15F" manufactured by Sumitomo Seika Chemicals Co., Ltd.) (solid content: 100% by mass, viscosity of 2% by mass aqueous solution at 20°C: 3000 to 6000 mPa·s) diluted with a solvent (water) to a solid content of 2% by mass, and 60 phr (100 parts by mass of modified polyvinyl alcohol per 100 parts by mass of modified polyvinyl alcohol) of a titanium-based crosslinking agent ("ORGATIX TC400" manufactured by Matsumoto Fine Chemical Co., Ltd.) was used. The resin solution obtained by mixing the above-mentioned acrylic resin and acrylic resin (60 parts by mass) was applied to one side of a substrate film ("Microporous Film" manufactured by 3M, thickness 30 μm) and dried at 100°C for 2 minutes to form a coating layer (thickness 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Comparative Example 1]
<<Laminated film manufacturing>>
Modified polyvinyl alcohol ("Exceval RS-2117" manufactured by Kuraray Co., Ltd.) (solid content: 100% by mass, viscosity of 4% by mass aqueous solution at 20°C: 26.5 mPa s, degree of saponification: 97.5-99 mol%) was applied to one side of a substrate film ("Microporous Film" manufactured by 3M Co., Ltd., thickness: 30 μm) and dried at 100°C for 2 minutes to form a coating layer (thickness: 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Comparative Example 2]
<<Laminated film manufacturing>>
Modified polyvinyl alcohol ("Gohsenex WO320N" manufactured by Mitsubishi Chemical Corporation) (solid content: 2% by mass, viscosity of 4% by mass aqueous solution at 20°C: 6.5 to 8.5 mPa s, degree of saponification: 97.5 to 99 mol%) was applied to one side of a substrate film ("Microporous Film" manufactured by 3M Corporation, thickness: 30 μm), and dried at 100°C for 2 minutes to form a coating layer (thickness: 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Comparative Example 3]
<<Laminated film manufacturing>>
Modified polyvinyl alcohol ("D Polymer DF-20" manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.) (solid content: 100% by mass, 4% by mass aqueous solution viscosity at 20°C: 28.5±3 mPa·s, saponification degree: 98-99 mol%) was diluted with a solvent (water) to a solid content of 2% by mass. A resin solution was obtained by mixing this with 10 phr of adipic acid dihydrazide ("ADH" manufactured by Tokyo Ohka Kogyo Co., Ltd.). The resin solution was applied to one side of a substrate film ("Microporous Film" manufactured by 3M Co., Ltd., thickness 30 μm) and dried at 100°C for 2 minutes to form a coating layer (thickness 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Comparative Example 4]
<<Laminated film manufacturing>>
Modified polyvinyl alcohol (Kuraray Co., Ltd.'s "Kuraray Poval 44-88") (solid content: 100% by mass, 4% by mass aqueous solution viscosity at 20°C: 40 to 48.0 mPa·s, saponification degree: 87.0 to 89 mol%) was applied to one side of a substrate film (3M Co., Ltd.'s "Microporous Film", thickness: 30 μm) and dried at 100°C for 2 minutes to form a coating layer (thickness: 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

[Comparative Example 5]
<<Laminated film manufacturing>>
Modified polyvinyl alcohol (Kuraray Co., Ltd.'s "Kuraray Poval 5-98") (solid content: 100% by mass, viscosity of 4% by mass aqueous solution at 20°C: 5.2 to 6.0 mPa s, degree of saponification: 98 to 99 mol%) was applied to one side of a substrate film (3M Co., Ltd.'s "Microporous Film", thickness: 30 μm), and dried at 100°C for 2 minutes to form a coating layer (thickness: 1 μm) on the substrate film.
In this way, a laminated film was obtained in which the coating layer was laminated on the substrate film.

<<Measurement of water vapor permeation rate of laminated film>>
The water vapor transmission rate of each of the laminate films of Examples 1 to 9 and Comparative Examples 1 to 5 obtained above was measured at 30°C and 97% RH using the cup method specified in JIS Z 0208. The measurement was carried out using a container with a transmission area of 5 ^cm2 containing 20 g of dried calcium chloride, and the water vapor transmission rate was calculated from the amount of moisture absorbed up to 3 hours after the start of the evaluation. The results are shown in Table 1.

<<Measurement of Air Resistance of Resin Film>>
The air permeability resistance of the laminated films of Examples 1 to 9 and Comparative Examples 1 to 5 obtained above was measured at 23°C and 50% humidity by the Oken method specified in JIS P 8117: 2009. The results are shown in Table 1.

<<Evaluation of the Deterioration Prevention Effect of Laminated Film>>
A 0.2 cm (iron plate) piece measuring 5 cm x 5 cm was immersed in water for 10 minutes, and then placed in a bag made by laminating a 12 cm x 12 cm laminated film or films one on top of the other and welding them at a temperature of 1900°C, which was produced in each of the above examples and comparative examples, and carbon dioxide was sealed inside to form a package.
After storing the package under normal pressure at 23° C. for 5 days, the iron pieces in storage were taken out of the package as test pieces, and the occurrence of rust on the surface of the iron pieces was visually confirmed.
<Evaluation criteria>
A: No rust was observed on the surface of the metal piece.
B: Rust is present on part of the metal surface.
C: Rust is present on the entire metal piece.

<<Water resistance evaluation>>
<Measurement of change in water vapor permeation rate of coating layer due to hot water treatment>
The laminate films of Examples 1 to 9 and Comparative Examples 1 to 5 obtained above were immersed in hot water at 95°C for 18 hours and then dried at 100°C for 60 minutes. The water vapor permeation rates of the laminate films before and after the hot water treatment were measured as described above, and the percentages (%) of the water vapor permeation rates of the laminate films before and after the hot water treatment were measured. The results are shown in Table 1.

<Measurement of mass change of coating layer due to hot water treatment>
The resin compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 5 were poured into aluminum cups and dried for 120 minutes to produce resin films with a thickness of 50 μm. These resin films were immersed in hot water at 95°C for 18 hours and then dried at 100°C for 60 minutes. The masses of the resin films before and after the hot water treatment were measured, and the ratio (%) of the mass to the mass of the resin film before the hot water treatment was measured. The results are shown in Table 1.

<Measurement of mass change of coating layer due to water treatment>
The resin compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 5 were poured into aluminum cups and dried for 120 minutes to produce resin films with a thickness of 50 μm. These resin films were immersed in water at 25°C for 18 hours and then dried at 100°C for 60 minutes. The masses of the resin films before and after the water treatment were measured, and the ratio (%) of the mass to the mass of the resin film before the water treatment was measured. The results are shown in Table 1.

As is clear from the above results, the laminate films of Examples 1 to 9 had water vapor permeation rates of 4000 g/ ^m² ·day or more, air permeability resistances of 5000 seconds or more, and rusting of metal pieces was suppressed. Furthermore, the ratio of the water vapor permeation rate of the laminate film after hot water treatment to the water vapor permeation rate before hot water treatment was 86 to 112%, the ratio of the mass of the laminate film after hot water treatment to the mass before hot water treatment was 75 to 100%, and the ratio of the mass of the laminate film after water treatment to the mass before water treatment was 93 to 99%, thereby suppressing dissolution of the coating layer in water. Furthermore, the laminate films of Examples 1 to 9 also had good anti-degradation effects.
In contrast, for the laminate films of Comparative Examples 1 to 5, the ratio of the water vapor permeation rate of the laminate film after hot water treatment to the water vapor permeation rate before hot water treatment exceeded 125%, and the ratio of the mass of the laminate film after hot water treatment to the mass before hot water treatment was 0 to 10%, indicating that all or most of the coating layer was dissolved in hot water. For the laminate film of Comparative Example 4, the ratio of the mass of the laminate film after water treatment to the mass before water treatment was 0%, indicating that the entire coating layer was dissolved in water. For the laminate film of Comparative Example 5, the ratio of the mass of the laminate film after water treatment to the mass before water treatment was 80%, indicating that the coating layer had high solubility in water. Furthermore, the laminate films of Comparative Examples 4 and 5 had poor anti-degradation effects.

This invention can be used to package metal items such as medical equipment, industrial materials, and electronic components.

1...Laminated film 2...Coating layer 3...Base material layer

Claims (4)

A laminated film comprising a substrate layer and a coating layer provided on one surface of the substrate layer,
the water vapor permeation amount of the laminated film measured by the cup method specified in JIS Z 0208 under conditions of 30°C and 97% RH is 4000 g/ ^m2 ·day or more ;
The air permeability resistance of the laminated film is 5000 seconds or more at 23°C and 50% RH , as measured by the Oken method specified in JIS P 8117:2009;
the water vapor permeation amount of the laminate film after a hot water treatment in which the laminate film is immersed in hot water at 95°C for 18 hours and dried at 100°C is 75 to 125% of the water vapor permeation amount of the laminate film before the hot water treatment,
the mass of the coating layer after the hot water treatment is 55 to 100% of the mass of the coating layer before the hot water treatment,
the coating layer contains a crosslinked gas barrier resin,
The crosslinked gas barrier resin can be formed by reacting an uncrosslinked gas barrier resin with a crosslinking agent,
The crosslinked gas barrier resin is a crosslinked resin obtained by crosslinking at least one selected from the group consisting of saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, polyether, polyurethane, polyamide, cellophane, cellulose, starch, and polyhydroxyethyl (meth)acrylate . The laminate film according to claim 1, wherein the mass of the coating layer after water treatment, in which the laminate film is immersed in water at 25°C for 18 hours and dried at 100°C, is 90 to 100% of the mass of the coating layer before the water treatment. The laminated film according to claim 1 or 2, wherein the thickness of the coating layer is 0.1 μm or more and 5.0 μm or less. 2. The laminate film according to claim 1, wherein the coating layer comprises a single layer containing a crosslinked resin obtained by crosslinking at least one selected from the group consisting of saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, polyether, and polyurethane.