JP2020163857A - Protective film, film laminate using the same and method for producing the same - Google Patents

Abstract

To provide a new protective film having an inorganic layer provided on one surface side of a base material film, which can obtain higher gas barrier property and a method for producing the same, and a film laminate using the protective film.SOLUTION: A protective film has such a structure that an inorganic layer and a crosslinked resin layer are layered in this order on one surface side of a base material film (1), in which the crosslinked resin layer contains alkali earth metal ions or alkali metal ions.SELECTED DRAWING: None

Description

The present invention relates to a protective film having excellent gas barrier properties, a film laminate using the protective film, and a method for producing the same.

Conventionally, a gas barrier film having a structure in which a plastic film is used as a base material and a layer (referred to as "inorganic material layer") mainly made of an inorganic substance such as an inorganic oxide vapor deposition layer is formed on the surface of the base material has been used for water vapor or oxygen. It is widely used for packaging of articles that require blocking of various gases such as, for example, packaging for preventing deterioration of foods, industrial products, pharmaceuticals, and the like.
In addition to packaging applications, new applications such as liquid crystal display elements, solar cells, electromagnetic wave shields, touch panels, EL substrates, and color filters have also been attracting attention in recent years.

Various improvements have been studied for gas barrier films having such an inorganic layer.
For example, from the viewpoint of providing transparency and gas barrier properties, as well as boil resistance and retort resistance that do not cause deposition, etc., a functional group-containing silane coupling agent or silane coupling agent is applied to at least one surface of the plastic base material. A vapor-deposited film is disclosed in which a primer layer composed of a composite of a hydrolyzate, a polyol and an isocyanate compound, and an inorganic oxide thin film layer having a thickness of 5 to 300 nm are sequentially laminated (Patent Document 1).

Further, from the viewpoint of excellent gas barrier properties and adhesion strength between the constituent layers, it is composed of a base film / inorganic thin film layer / anchor layer / inorganic thin film layer, and the thickness of the anchor layer is 0.1 to 10 nm. The film is disclosed (Patent Document 2).

Further, in a barrier film formed by laminating a silicon oxide film (SiOx) as a barrier layer on one side or both sides of a plastic base material, the barrier layer is composed of at least two or more silicon oxide films, and the silicon oxide The film thickness per film layer is 10 nm or more and 50 nm or less, the film thickness of the barrier layer composed of the two or more silicon oxide films is 20 nm or more and 200 nm or less, and the ratio of carbon atoms in the barrier layer. Is 10 at. A gas barrier film having a value of% or less is disclosed (Patent Document 3).

Japanese Unexamined Patent Publication No. 2000-238172 International Publication No. 2007-034773 Pamphlet JP-A-2009-101548

An object of the present invention is to provide a protective film having an inorganic layer on one side of a base film, a new protective film capable of obtaining higher gas barrier properties, a method for producing the same, and a film using the protective film. The purpose is to provide a laminate.

The present invention is a protective film having a structure in which an inorganic material layer and a crosslinked resin layer are laminated in this order on one side of the base film (1), and the crosslinked resin layer is an alkaline earth metal ion or an alkali. We propose a protective film containing metal ions.

The present invention also relates to a water-soluble or water-dispersible binder resin, a water-soluble alkaline earth metal compound, or a method for producing a protective film in which an inorganic material layer and a crosslinked resin layer are sequentially formed on one side of the base film (1). We propose a method for producing a protective film, which comprises applying and cross-linking a cross-linkable resin composition containing a water-soluble alkali metal compound to form a cross-linked resin layer.

The present invention further proposes a film laminate having a structure in which a base film (2) is bonded to the surface of a crosslinked resin layer of the protective film via an adhesive layer.
Further, a film having a structure in which the crosslinked resin layer of the protective film provided with the base film (2) and the crosslinked resin layer is bonded to the surface of the crosslinked resin layer of the protective film via an adhesive layer. We propose a laminate.

In the protective film proposed by the present invention, higher gas barrier properties can be obtained when the crosslinked resin layer contains alkaline earth metal ions or alkali metal ions. Therefore, the protective film and the film laminate using the protective film proposed by the present invention prevent deterioration of, for example, packaging of articles that require blocking of various gases such as water vapor and oxygen, such as foods, industrial products, and pharmaceuticals. It can be widely used as a packaging material for. 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 examples of embodiments. However, the present invention is not limited to the embodiments described below.

<< This protective film >>
The protective film (referred to as the "protective film") according to an example of the embodiment of the present invention has an anchor layer, an inorganic material layer and a crosslinked film on one side of the base film (1) (referred to as the "base film"). The resin layers are laminated in this order, and the crosslinked resin layer is a protective film containing alkaline earth metal ions or alkali metal ions. However, the anchor layer may be omitted.

In this protective film, higher gas barrier properties can be obtained by containing alkaline earth metal ions or alkali metal ions in the crosslinked resin layer. Presuming this mechanism, alkaline earth metal ions or alkali metal ions are present in the gaps in the inorganic layer, for example, the gaps between the inorganic particles constituting the inorganic layer, the grain boundaries of the inorganic material, and defects. , It can be estimated that the gas barrier property is enhanced.
Further, when the alkaline earth metal ion or the alkali metal ion is present in the crosslinked resin layer, the alkaline earth metal ion or the alkali metal ion diffuses and permeates into the adjacent inorganic layer, and as described above, in the inorganic layer. It can be presumed that the gas barrier property is enhanced because alkaline earth metal ions or alkali metal ions invade the gaps and exist.
Therefore, when the crosslinked resin layer contains alkaline earth metal ions or alkali metal ions, higher gas barrier properties can be obtained.

<This base film>
The material and composition of the base film constituting the protective film are not limited as long as they are transparent and have the necessary and sufficient rigidity as the protective film.

The base film may have a single-layer structure or a multi-layer structure.
When the base film has a multi-layer structure, it may have a two-layer or three-layer structure, or may have a four-layer or more multi-layer structure.

Regardless of whether the base film has a single-layer structure or a multi-layer structure, it is preferable that the main component resin of each layer is polyester.
At this time, the "main component resin" means the resin having the highest content ratio among the resins constituting each layer, for example, 50% by mass or more, particularly 70% by mass or more, particularly 80% by mass of the resins constituting each layer. It is a resin that occupies% or more (including 100% by mass).
Each layer of the base film may contain a resin other than polyester or a component other than the resin as long as it contains polyester as the main component resin.

The polyester may be a homopolyester or a copolymerized polyester. When it is made of homopolyester, it is preferably obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid. Examples of the aliphatic glycol include ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol and the like. As a typical polyester, polyethylene terephthalate and the like can be exemplified.

On the other hand, examples of the dicarboxylic acid component of the copolymerized polyester include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, sebacic acid and the like, and ethylene as the glycol component. One or more of glycol, diethylene glycol, propylene glycol, butanediol, 4-cyclohexanedimethanol, neopentyl glycol and the like can be mentioned.

Specific examples of polyester as the main component resin of the base film include polyethylene terephthalate (PET), polyethylene terephthalate (PEN), polybutylene terephthalate (PBT), polybutylene terephthalate (PBN), polyallylates, and the like. Examples thereof include polyether sulphon, polycarbonate, polyether ketone, polysulphon, polyphenylene terephide, polyester-based liquid crystal polymer, triacetyl cellulose, cellulose derivative, polypropylene, polyamides, polyimide, polycycloolefins, and the like. Among these, a film containing PET, PEN or the like as a main component resin is particularly preferable in terms of handleability.

The base film may contain particles for the purpose of roughening the surface of the film to impart slipperiness and for the main purpose of preventing scratches in each step.
The type of the particles is not particularly limited as long as it is a particle capable of imparting slipperiness. For example, inorganic particles such as silica calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, titanium oxide, acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, benzoguanamine resin. Organic particles such as, etc. can be mentioned. These may be used alone or in combination of two or more of them.
Further, during the polyester manufacturing process, precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed can also be used.
The shape of the particles is not particularly limited. For example, it may be spherical, lumpy, rod-shaped, flat-shaped or the like.
Further, the hardness, specific gravity, color and the like of the particles are not particularly limited. Two or more kinds 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 μm or less, and more preferably 0.5 μm or more or 2.5 μm or less. When the average particle size of the particles is 5 μm or less, the surface roughness of the base film does not become too rough. Therefore, in that respect, when the anchor layer or the inorganic layer is formed on the surface of the base film. Problems can be reduced.

The particle content is preferably 5% by mass or less of the present base film, particularly 0.0003% by mass or more or 3% by mass or less, and among them, 0.01% by mass or more or 2% by mass or less. More preferred. By setting the particle content within the above range, it is possible to achieve both slipperiness and transparency of the film, which is preferable.

The method of adding the particles to the base film is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage in the production of polyester. It is preferable to add the ester after the esterification or transesterification reaction is completed.

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

The thickness of the base film is not particularly limited as long as it can be formed as a film, and is preferably 9 μm to 100 μm, particularly 12 μm or more or 75 μm or less, and 15 μm or more or 60 μm or less. It is more preferable to have it.

The base film can be formed, for example, by forming a resin composition into a film shape by a melt film forming method or a solution film forming method. In the case of a multi-layer structure, co-extrusion may be performed.
Further, it may be uniaxially stretched or biaxially stretched, and is preferably a biaxially stretched film from the viewpoint of rigidity.

<This anchor layer>
The anchor layer (referred to as "the anchor layer") constituting the protective film is a layer for enhancing the adhesiveness between the base film and the inorganic layer, and the adhesion between the base film and the inorganic layer. The composition is arbitrary as long as it can enhance the sex.

The anchor layer can be formed from, for example, an anchor coating agent.
Examples of the anchor coating agent include solvent-based or water-based polyester, urethane resin, acrylic resin, vinyl alcohol resin, ethylene vinyl alcohol resin, vinyl modified resin, oxazoline group-containing resin, carbodiimide group-containing resin, epoxy group-containing resin, and isocyanate group. Examples thereof include a containing resin, an alkoxyl group-containing resin, a modified styrene resin, a modified silicone resin, and the like, and these can be used alone or in combination of two or more. Among them, at least one selected from polyester, urethane resin, acrylic resin, oxazoline group-containing resin, carbodiimide group-containing resin, epoxy group-containing resin, isocyanate-containing resin and copolymers thereof from the viewpoint of adhesion and heat resistance. It is preferable to use it alone or in combination of two or more, and among them, one or more of polyester, urethane resin, and acrylic resin, and oxazoline group-containing resin, carbodiimide group-containing resin, epoxy group-containing resin, and isocyanate group-containing resin. It is preferable to use at least one selected type alone or in combination with two or more types.

If the thickness of the anchor layer is 5 μm or less, the slipperiness is good, there is almost no peeling from the base film due to the internal stress of the anchor layer itself, and if the thickness is 0.005 μm or more. , It is preferable because it can maintain a uniform thickness.
From this point of view, the thickness of the anchor layer is preferably 0.005 to 5 μm, more preferably 0.01 μm or more or 1 μm or less, and more preferably 0.02 μm or more or 0.5 μm or less.

<Genuine inorganic layer>
The inorganic layer (referred to as "the present inorganic layer") constituting the present protective film is a layer containing an inorganic substance, particularly an inorganic oxide as a main material.
The "main material" means a material that occupies 50% by mass or more, particularly 70% by mass or more, particularly 80% by mass or more, and 90% by mass or more (including 100% by mass) of the present inorganic material layer.

This inorganic layer is a layer capable of enhancing the property of suppressing gas permeation (also referred to as "gas barrier property"), particularly the water vapor barrier property. Further, in the case of this inorganic layer, higher gas barrier properties can be obtained by containing alkaline earth metal ions or alkali metal ions. Inferring this mechanism, as described above, gaps in the inorganic layer, for example, gaps between the inorganic particles constituting the inorganic layer, inorganic crystal grain boundaries, defects, for example, voids in the silica crystal structure in the silica vapor deposition film, etc. It can be presumed that the passage of gas can be blocked and the gas barrier property is enhanced by invading the alkaline earth metal ion or the alkali metal ion to fill the gap.

In order for the inorganic layer to contain an alkaline earth metal ion or an alkali metal ion, the crosslinked resin layer is formed so that the adjacent crosslinked resin layer contains the alkaline earth metal ion or the alkali metal ion. Also, the inorganic layer can be made to contain alkaline earth metal ions or alkali metal ions. That is, if the adjacent crosslinked resin layer contains an alkaline earth metal ion or an alkali metal ion, it is not necessary for the present inorganic layer to contain the alkaline earth metal ion or the alkali metal ion from the beginning.
The method for making the present inorganic layer contain alkaline earth metal ions or alkali metal ions is not limited to these methods.

As the alkali metal ion, either or both of sodium ion and potassium ion can be exemplified. However, it is not limited to these.
The alkali metal ion in the present inorganic oxide may exist in the state of an ion or may exist in the state of an alkali metal compound.
Examples of the alkali metal compound include at least one selected from water-soluble alkali metals such as sodium hydroxide, sodium chloride, potassium hydroxide and potassium chloride.

Further, as the alkaline earth metal ion, either or both of magnesium ion and calcium ion can be exemplified. However, it is not limited to these.
The alkaline earth metal ion in the present inorganic oxide may exist in the state of an ion or may exist in the state of an alkaline earth metal compound.
Examples of the alkaline earth metal compound include at least one selected from water-soluble alkaline earth metal compounds such as magnesium chloride and calcium hydroxide.
From the viewpoint of improving the gas barrier property, it is more preferable to contain an alkali metal compound.

Examples of the inorganic substance as the main material constituting the inorganic substance layer include a group consisting of silicon oxide, silicon nitride, silicon nitride nitride, silicon carbide, silicon oxide nitride, aluminum oxide, aluminum nitride, aluminum nitride and aluminum oxide. One or more inorganic compounds selected from the above can be mentioned.

Examples of the inorganic layer 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 CVD inorganic substance formed by a chemical vapor deposition (CVD) method. A layer, a coated inorganic layer formed by a method in which inorganic particles are dispersed in an organic polymer and applied is preferable.
Here, a PVD inorganic layer, a plasma-assisted vapor-deposited inorganic layer, and a CVD inorganic layer will be described as typical examples of the present inorganic layer.

(PVD inorganic layer)
It is preferable that the present inorganic layer includes at least one PVD inorganic layer formed by the physical vapor deposition method (PVD) in that higher gas barrier properties can be exhibited.

As an example of the PVD inorganic layer, a layer composed of a silicon oxide represented by SiOx (1.0 <x ≦ 2.0) can be mentioned. At this time, if the x value (lower limit value) of SiOx becomes smaller, the gas permeability becomes smaller and the gas barrier property of the present inorganic layer can be enhanced, while the silicon oxide film itself becomes yellowish and transparent. It tends to be less sexual. From this point of view, x in the SiOx is more preferably 1.2 ≦ x ≦ 2.0, and more preferably 1.4 ≦ x ≦ 2.0.
The composition can be confirmed by XPS analysis or the like.

The preferable pressure at the time of forming the PVD inorganic layer is preferably 1 × 10 ^-7 Pa to 1 Pa, particularly 1 × 10 ^-6 Pa, from the viewpoint of gas barrier property, vacuum exhaust capacity, and degree of oxidation of the SiOx layer to be formed. It is more preferably 1 × 10 ^-1 Pa or less, and more preferably 1 × 10 ^-4 Pa or more or 1 × 10 ⁻² Pa or less.
The partial pressure at the time of introducing oxygen is preferably in the range of 10 to 90% with respect to the total pressure, and more preferably 20% or more or 80% or less.

As described above, the present inorganic layer preferably includes at least one PVD inorganic layer. At this time, the present inorganic layer may have a single-layer structure composed of a PVD inorganic layer, or may have the same or different composition as the CVD inorganic layer described later on the PVD inorganic layer in order to secure higher gas barrier properties. It may be a multi-layer (two or more layers) structure in which PVD inorganic layers are laminated. For example, a PVD inorganic layer and a CVD inorganic layer may be alternately formed (for example, a three-layer structure consisting of a PVD inorganic layer, a CVD inorganic layer, and a PVD inorganic layer). Further, by forming the CVD inorganic material layer on the PVD inorganic material layer, defects and the like generated in the PVD inorganic material layer are sealed, and the gas barrier property and the adhesion between layers tend to be improved.

(Plasma assisted vapor deposition inorganic material layer)
If the present inorganic layer is composed of the plasma-assisted vapor-deposited inorganic layer, the transparency can be improved without lowering the gas barrier property.
The "plasma-assisted thin-film deposition method" refers to a method of vapor-depositing a vapor-deposited material while ionizing it with plasma during vacuum-film deposition, or irradiating gas ions from a separately provided ion source.
If the present inorganic layer is formed by the plasma-assisted thin-film deposition method, oxygen can be efficiently taken into the present inorganic layer, and as described above, the transparency can be improved without lowering the gas barrier property.
A thin film produced by ordinary vacuum deposition has less energy than the thin film produced by sputtering or the like, and is not advantageous in terms of film strength and density. On the other hand, according to the plasma-assisted thin-film deposition method, since the vapor-deposited substance obtains energy, a thin film having high strength and density can be formed even in vacuum-film deposition. Further, since the excited species in the plasma are highly reactive, it is possible to form a thin film in which the evaporation source is arbitrarily oxidized, nitrided, or carbonized by introducing a gas such as oxygen, nitrogen, or acetylene. By providing the present inorganic layer by this method, there is also an advantage that a film can be formed faster than the sputtering or plasma CVD method.

As an example of the plasma-assisted vapor-deposited inorganic material layer, a layer composed of a silicon oxide represented by SiOx (1.0 <x ≦ 2.0) can be mentioned. As described above, if oxygen gas is introduced into the inorganic layer by the plasma-assisted vapor deposition method, the oxygen molar ratio of silicon oxide can be increased, so x in the SiOx is set to 1.2 ≦ x ≦ 2.0. Further, since 1.4 ≦ x ≦ 2.0 can be set, the transparency can be further improved. In addition, when the oxygen molar ratio (x) becomes large, the gas barrier property usually decreases, but the excellent gas barrier property can be maintained for this protective film.

(CVD Inorganic Layer)
When the present inorganic layer includes at least one CVD inorganic layer, the CVD inorganic layer is composed of a thin film formed by chemically vapor deposition of at least one selected from a metal, a metal oxide, a metal nitride and a silicon compound. Is preferable.
As the metal oxide or metal nitride, it is preferable to use the metal oxide, nitride or a mixture thereof from the viewpoint of gas barrier property and adhesion. Further, it may be a metal oxide or a metal nitride obtained by plasma-decomposing an organic compound.
Further, from the viewpoint of gas barrier property and adhesion, it is also preferable to use a metal or compound such as silicon or aluminum.

As a preferable example of the present inorganic layer, a composition composed of a silicon compound such as silicon oxide, silicon oxide, silicon oxide, silicon oxide, silicon nitride, and silicon nitride, and a thin film formed by chemically vapor deposition of at least one selected from aluminum oxide. Can be mentioned.
Examples of the silicon compound include silane, tetramethoxysilane, tetraethoxysilane, tetra n-propoxysilane, tetraisopropoxysilane, tetra n-butoxysilane, tetrat-butoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, and diethyldimethoxy. Silane, diphenyldimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, phenyltriethoxysilane, (3,3,3-trifluoropropyl) trimethoxysilane, hexamethyldisiloxane, bis (dimethylamino) dimethylsilane, bis (Dimethylamino) methylvinylsilane, bis (ethylamino) dimethylsilane, N, O-bis (trimethylsilyl) acetamide, bis (trimethylsilyl) carbodiimide, diethylaminotrimethylsilane, dimethylaminodimethylsilane, hexamethyldisilazane, hexamethylcyclotrisilazane , Heptamethyldisilazane, nonamethyltrisilazane, octamethylcyclotetrasilazane, tetrakisdimethylaminosilane, tetraisosianatosilane, tetramethyldisilazane, tris (dimethylamino) silane, triethoxyfluorosilane, allyldimethylsilane, allyltrimethylsilane , Benzyltrimethylsilane, bis (trimethylsilyl) acetylene, 1,4-bistrimethylsilyl-1,3-butadiine, di-t-butylsilane, 1,3-disilabtan, bis (trimethylsilyl) methane, cyclopentadienyltrimethylsilane, phenyl Dimethylsilane, phenyltrimethylsilane, propargyltrimethylsilane, tetramethylsilane, trimethylsilylacetylene, 1- (trimethylsilyl) -1-propine, tris (trimethylsilyl) methane, tris (trimethylsilyl) silane, vinyltrimethylsilane, hexamethyldisilane, octamethyl Cyclotetrasiloxane, tetramethylcyclotetrasiloxane, hexamethyldisiloxane, hexamethylcyclotetrasiloxane, M silicate 51 and the like can be mentioned.

The CVD inorganic layer preferably contains carbon. At that time, the carbon content of the CVD inorganic layer was 0.5 at. % Or more, preferably 1 at. % Or more, more preferably 2 at. It should be% or more.
Since the CVD inorganic layer contains a small amount of carbon, stress relaxation can be efficiently performed and curling of the barrier film itself can be reduced. On the other hand, from the viewpoint of gas barrier property, the carbon content in the CVD inorganic layer is 20 at. It is preferably less than%, and above all, 10 at. It is more preferably less than%, and among them, 5 at. Most preferably, it is% or less.
By setting the carbon content in the above range, the surface energy of the inorganic layers is increased, and the adhesion between the inorganic layers is improved, so that the bending resistance and peeling resistance of the barrier film are improved.
In addition, "at.%" Indicates an atomic composition percentage (atomic%).
In addition, the composition can be confirmed by XPS analysis or the like.

The CVD inorganic layer can be formed, for example, by the method described in JP2013-226829.
For example, when a layer made of silicon oxide is formed by a chemical vapor deposition (CVD) method, a silicon compound can be used as a raw material in any state of gas, liquid, or solid under normal temperature and pressure. be able to. In the case of gas, it can be introduced into the discharge space as it is. In the case of a liquid or solid, it is preferable to vaporize it by means such as heating, bubbling, depressurization, and ultrasonic irradiation. Alternatively, it may be used after being diluted with a solvent. As the solvent, an organic solvent such as methanol, ethanol, n-hexane or a mixed solvent thereof can be used.

When performing the chemical vapor deposition (CVD) method, the chemical vapor deposition (CVD) is carried out while transporting the base film, particularly the base film provided with the anchor layer, at a speed of 100 m / min or more in a reduced pressure environment of 10 Pa or less. ) It is preferable to carry out the method.
The pressure when forming a thin film by the chemical vapor deposition method (CVD) is preferably performed under reduced pressure in order to form a dense thin film, and is preferably 10 Pa or less from the viewpoint of film forming speed and barrier property. Of these, 1 × 10 ⁻² Pa or more or 10 Pa or less, and among them, 1 × 10 ^-1 Pa or more or 1 Pa or less is more preferable.

The CVD inorganic layer may be subjected to a cross-linking treatment by electron beam irradiation, if necessary, in order to improve water resistance and durability.

(Layer composition of this inorganic layer)
The inorganic layer may have a single layer structure or a multi-layer structure having two or more layers.
For example, as an example of a multi-layer structure having two or more layers, one layer thereof is an inorganic substance, for example, an inorganic substance layer composed of only an inorganic oxide, and the other layer is an inorganic / organic mixed layer composed of an inorganic substance, for example, an inorganic oxide and an organic substance. For example,
By forming the present inorganic layer by mixing the organic substance with the inorganic substance, the present inorganic layer can be made into a relatively flexible layer. Therefore, by providing such a flexible layer, the gas barrier property can be enhanced. In some cases. That is, the coarse protrusions of the base film are the starting points, and minute defects called pinholes are generated on the surface of the inorganic layer, or the raw material is lumped and adheres to the surface of the inorganic layer during heat deposition. Minor defects may occur, and the gas barrier property may decrease as the gas passes through the voids due to these defects. Therefore, by laminating and laminating the above-mentioned flexible layer on the surface, the defect can be filled and the gas barrier property may be enhanced.
The term "flexible layer" as used herein includes the meaning of a layer that relaxes the stress of the inorganic layer so that it can be used for applications that require flexibility, such as flexible applications.

As described above, in order to form a flexible layer, an organic substance may be mixed with the inorganic substance to form a layer, and the organic substance at that time includes, for example, an organic substance such as a polyester resin, an acrylic resin, a urethane resin, or a PVA. In addition, organic fillers can be mentioned.

(thickness)
The thickness of the inorganic layer (the total thickness of the inorganic layer when the inorganic layer has a multi-layer structure) is preferably 0.1 nm to 500 nm, particularly 1 nm or more or 300 nm or less, and 5 nm or more or 100 nm or less. It is more preferable to have it.
When the thickness of the inorganic material layer is within the above range, it is possible to secure the desired gas barrier property.

<This crosslinked resin layer>
The crosslinked resin layer (referred to as "the present crosslinked resin layer") constituting the present protective film may be a layer containing a crosslinked resin formed by cross-linking the resin, and is preferably a layer having the crosslinked resin as a basic skeleton. ..

Since the crosslinked resin layer is more flexible than the inorganic layer, it can absorb the surface irregularities of the inorganic layer, thereby improving the gas barrier property. It is also possible to suppress yellowing or yellowish browning caused by the present inorganic layer.
When the crosslinked resin layer contains alkaline earth metal ions or alkali metal ions as described above, higher gas barrier properties can be obtained.
The crosslinked resin layer may also have a role of supplying alkaline earth metal ions or alkali metal ions to the inorganic layer. That is, when the crosslinked resin layer contains an alkaline earth metal ion or an alkali metal ion, it diffuses and moves into the present inorganic layer in contact with the present crosslinked resin layer, so that the alkaline earth metal ion or alkali is transferred to the present inorganic layer. Metal ions can be supplied.

The crosslinked resin layer preferably contains alkaline earth metal ions or alkali metal ions, if necessary. That is, it is preferable to contain an alkaline earth metal compound that produces alkaline earth metal ions or an alkali metal compound that produces alkali metal ions.
When the present inorganic layer does not contain an alkaline earth metal ion or an alkali metal ion, it preferably contains an alkaline earth metal ion or an alkali metal ion. However, even when the present inorganic layer contains alkaline earth metal ions or alkali metal ions, the crosslinked resin layer may contain alkaline earth metal ions or alkali metal ions.
As described above, if the crosslinked resin layer contains an alkaline earth metal ion or an alkali metal ion, the alkaline earth metal ion or the alkali metal ion in the crosslinked resin layer diffuses and permeates into the inorganic material layer. The inorganic layer can contain alkaline earth metal ions or alkali metal ions.

As the alkali metal ion, either or both of sodium ion and potassium ion can be exemplified. However, it is not limited to these.
The alkali metal ion may exist in the state of an ion or may exist in the state of an alkali metal compound.
Examples of the alkali metal compound include at least one selected from water-soluble alkali metals such as sodium hydroxide, sodium chloride, potassium hydroxide and potassium chloride.

Further, as the alkaline earth metal ion, either or both of magnesium ion and calcium ion can be exemplified. However, it is not limited to these.
The alkaline earth metal ion in the present inorganic oxide may exist in the state of an ion or may exist in the state of an alkaline earth metal compound.
Examples of the alkaline earth metal compound include at least one selected from water-soluble alkaline earth metal compounds such as magnesium chloride and calcium hydroxide.
From the viewpoint of improving the gas barrier property, it is more preferable to contain an alkali metal compound.

(Composition of this crosslinked resin layer)
The crosslinked resin layer is a layer having a crosslinked resin structure formed by crosslinking and curing a crosslinkable resin composition containing a binder resin as a main component resin and other components such as a curing agent or a crosslinking initiator. Is preferable.
At this time, the "main component resin" means the resin having the highest content (mass%) among the resins constituting the main crosslinked resin layer. The content ratio of the crosslinked resin layer is preferably 50% by mass or more, particularly 70% by mass or more, particularly 80% by mass or more, and particularly preferably 90% by mass or more (including 100% by mass).

When the crosslinked resin layer contains an alkaline earth metal ion or an alkali metal ion, the binder resin as the main component resin contains a water-soluble or water-dispersible binder resin, and further contains an alkaline earth metal ion. A crosslinkable resin composition containing a water-soluble alkaline earth metal compound or a water-soluble alkali metal compound that produces an alkali metal ion, a solvent as required, and a curing agent or a cross-linking initiator as required is crosslinked. It is preferable that the layer is made of a crosslinked resin structure.
When forming the present crosslinked resin layer, for example, a water-soluble or water-dispersible binder resin, a water-soluble alkaline earth metal ion or a water-soluble alkali metal compound, and, if necessary, a curing agent or a cross-linking initiator. It is preferable that the crosslinkable resin composition containing an aqueous solvent is applied onto the present inorganic layer and crosslinked to form the present crosslinked resin layer. At this time, as the crosslinking method, either thermal crosslinking or optical crosslinking can be adopted.

(Binder resin)
Examples of the water-soluble or water-dispersible binder resin include water-soluble epoxy resins, water-dispersible polyurethane resins, and water-dispersible urethane acrylates, which will be described below.

[Water-soluble epoxy resin]
As the water-soluble epoxy resin, it is preferable to use a water-soluble epoxy resin which is a prepolymer having an epoxy group at the terminal.
Of these, those having an aromatic prepolymer chain are preferable. Specific examples include an epoxy resin having a glycidylamine moiety derived from metaxylylene diamine, an epoxy resin having a glycidylamine moiety derived from 1,3-bis (aminomethyl) cyclohexane, and glycidyl derived from diaminodiphenylmethane. Epoxy resin with amine moiety, glycidyl amine moiety and / or glycidyl ether moiety derived from paraaminophenol, epoxy resin with glycidyl ether moiety derived from bisphenol A, glycidyl ether moiety derived from bisphenol F Examples thereof include an epoxy resin having a glycidyl ether moiety derived from phenol novolac, an epoxy resin having a glycidyl ether moiety derived from phenol novolac, and an epoxy resin having a glycidyl ether moiety derived from resorcinol. Among these, an epoxy resin having a glycidylamine moiety derived from metaxylylenediamine is particularly preferable.

[Water-dispersible polyurethane resin]
As the water-dispersible polyurethane resin, a polyurethane compound obtained by reacting a polyol compound containing no carboxyl group in the molecule with a polyisocyanate compound is forcibly emulsified in water by using surface activity to obtain water dispersibility. Polyurethane resin can be mentioned. However, it is not limited to this.

[Water-dispersed urethane acrylate]
The aqueous dispersion type urethane acrylate is obtained by mixing a urethane acrylate raw material, an emulsifier such as an anionic and / or nonionic reactive emulsifier, and an oil-soluble polymerization initiator, and using an emulsifier such as a homomixer or super. Examples thereof include urethane acrylate, which is an aqueous dispersion obtained by emulsion polymerization in a manner of dispersing while heat-treating with a sonic disperser or the like. However, it is not limited to this.

As the urethane acrylate raw material, a radically polymerizable oligomer having two or more acryloyl groups or methacryloyl groups in one molecule can be used.
Examples of commercially available urethane acrylate products include Beam Set 505A-6 (manufactured by Arakawa Chemical Industry Co., Ltd.), Ebeclyl270 (manufactured by Daicel Industries, Ltd.), UA-160TM, UA-7100, (Shin Nakamura Chemical Industry Co., Ltd.), and the like. To.

The emulsifier is not particularly limited as long as it can be used for emulsion polymerization.
As the anionic reactive emulsifier, commercially available products such as Aqualon series: KH-05, KH-10, AR-10, AR-20 (trade name: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Antox-MS-60, etc. Antox-MS-2N (manufactured by Japan Emulsifier Co., Ltd.), Adecaria soap series: SE-10N, SE-20N, SR-10 (manufactured by ADEKA) can be mentioned. Among them, those made of sulfonate are preferable.
Examples of the nonionic reactive emulsifier include commercially available products such as Adecaria Soap Series: NE-10, NE-20, NE-30, ER-10, ER-20, ER-30, ER-40 (manufactured by ADEKA). , Latemul series: PD-420, PD-430, PD-450 (Kao) and the like.

Examples of the oil-soluble polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2-methylpropanenitrile), and 2,2'-azobis- (2,4-dimethyl). Pentannitrile), 2,2'-azobis- (2-methylbutanenitrile), 1,1'-azobis- (cyclohexanecarbonitrile), 2,2'-azobis- (2,4-dimethyl-4-methoxyvalero) Azo (azobis nitrile) type initiators such as nitrile), 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobis- (2-amidinopropane) hydrochloride, peroxide, peroxide Benzoyl, cumenehydroperoxide, hydrogen peroxide, acetyl peroxide, lauroyl peroxide, persulfate (eg ammonium persulfate), peracid ester (eg t-butylperoctate, α-cumylperoxypivalate and t-butyl) Peroxide-type initiators such as peroctate) can be exemplified.

(Water-soluble alkaline earth metal compound or water-soluble alkali metal compound)
The water-soluble alkali metal compound may be any compound capable of supplying alkali metal ions, for example, sodium ions (Na ⁺ ) and potassium ions (K ⁺ ). Specifically, for example, sodium chloride, sodium hydroxide, potassium hydroxide, potassium chloride and the like can be mentioned.

The water-soluble alkaline earth metal compound may be any compound capable of supplying alkaline earth metal ions such as magnesium ion (Mg ²⁺ ) and calcium ion (Ca ²⁺ ). Specifically, for example, magnesium chloride, magnesium hydroxide, calcium hydroxide, calcium chloride and the like can be mentioned.

The amount of the water-soluble alkaline earth metal compound or the water-soluble alkali metal compound added is preferably 0.0001 parts by mass to 5.0 parts by mass based on the total mass (100 parts by mass) of the binder resin. It is preferably 0.001 part by mass to 5.0 part by mass, and more preferably 0.01 part by mass to 5.0 part by mass.

(Curing agent or cross-linking initiator)
The curing agent or the cross-linking initiator is preferably used as appropriate depending on whether a cross-linking method of thermal cross-linking or photo-crosslinking is selected, and what is used as the binder resin.
For example, when a water-soluble epoxy resin is used as the binder resin, it is preferable to use an amine compound as a curing agent, and among them, aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone are preferable.

When the crosslinkable resin composition is photocrosslinked, it is preferable to add a photopolymerization initiator.
The photopolymerization initiator is not particularly limited, and examples thereof include a ketone-based photopolymerization initiator and an amine-based photopolymerization initiator.

(solvent)
As the aqueous solvent, water or an alcohol solvent can be used as the main solvent.
Specific examples of the alcohol solvent include methanol, ethanol, isopropyl alcohol, butanol and the like. However, it is not limited to these.
If necessary, an organic solvent such as ethyl acetate or toluene may be used as long as the gist of the present invention is not impaired.

(Other ingredients)
The crosslinked resin layer may contain other components or materials in addition to the above-mentioned materials.
Examples of the "other component or material" include an inorganic filler, an oxygen scavenger, a coupling agent, a curing accelerator and the like.

The inorganic filler contains inorganic fillers such as silica, alumina, mica, talc, aluminum flakes, and glass flakes in order to improve various performances such as gas barrier property, impact resistance, and heat resistance of the crosslinked resin layer. You may be doing it. Further, when considering the transparency of the top coat layer, it is preferable that the inorganic filler is in the form of a flat plate.

The oxygen scavenger may be any compound having an oxygen scavenging function. For example, low molecular weight organic compounds that react with oxygen such as hindered pheno, vitamin C, vitamin E, organic phosphorus compounds, gallic acid, and pyrogallol, and transition metal compounds such as cobalt, manganese, nickel, iron, and copper can be mentioned. Can be done.

The coupling agent can be contained in the crosslinked resin layer as needed from the viewpoint of improving the adhesion between the crosslinked resin layer and the inorganic material layer or improving the gas barrier property.
As the coupling agent, a coupling agent such as a silane coupling agent or a titanium coupling agent may be added.
A commercially available product can be used as the coupling agent. Specifically, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, which can be obtained from Chisso Co., Ltd., Toray Dow Corning Co., Ltd., Shinetsu Chemical Industry Co., Ltd., etc. 2-Aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N, N'-bis [3-trimethoxysilyl] propyl] Amino-based such as ethylenediamine Silane coupling agent, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, etc. Epoxy-based silane coupling agent, methacryloxy-based silane coupling agent such as 3-methacryloxypropyltrimethoxysilane, mercapto-based silane coupling agent such as 3-mercaptopropyltrimethoxysilane, 3-isocyanoxidetriethoxysilane and the like. Silane-based silane coupling agents, aminosilane-based coupling agents such as SH-6026 and Z-6050 manufactured by Toray Dow Corning Co., Ltd., amino groups such as KP-390 and KC-223 manufactured by Shin-Etsu Chemical Industry Co., Ltd. Examples include the contained alkoxysilane.
Among them, those having an organic functional group that reacts with the binder resin composition of the crosslinked resin layer are desirable.
The amount of the coupling agent added is preferably in the range of 0.01% by mass to 5.0% by mass based on the total mass of the binder resin composition.

The curing accelerator is a curing accelerator such as N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, and benzyl alcohol so that the crosslinkable resin composition can be crosslinked at a low temperature. Organic solvents such as zinc phosphate, iron phosphate, calcium molybdate, vanadium oxide, water-dispersed silica, rust-preventive additives such as fumed silica, phthalocyanine-based organic pigments, condensed polycyclic organic pigments and other organic pigments, It is also possible to add each component such as an inorganic pigment such as titanium oxide, zinc oxide, calcium carbonate, barium sulfate, alumina, and carbon black in a required ratio amount.

(Amount of each component)
The ratio of the binder resin to the total solid component (100 parts by mass) in the crosslinkable resin composition is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and 90 parts by mass or less. It is preferably 80 parts by mass or less, and more preferably 80 parts by mass or less. When two or more kinds of binder resins are used in combination, the ratio of the total amount thereof is preferably within the above range. When two or more kinds of binder resins are used in combination, the ratio of the total amount thereof is preferably within the above range.

The ratio of the curing agent or the crosslink initiator to the total solid component (100 parts by mass) in the crosslinkable resin composition is preferably 5 parts by mass or more, particularly 10 parts by mass or more, and particularly 20 parts by mass or more. It is even more preferable to have it. On the other hand, the upper limit is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and particularly preferably 60 parts by mass or less.

The ratio of the binder resin and the solid components other than the curing agent or the cross-linking initiator to the total solid components (100 parts by mass) in the crosslinkable resin composition is preferably 0.01 parts by mass or more and 10 parts by mass or less, and 0 .1 part by mass or more or 10 parts by mass or less, and more preferably 1 part by mass or more or 10 parts by mass or less.

(Thickness of this crosslinked resin layer)
The thickness of the crosslinked resin layer is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 4 μm or more, and further preferably 6 μm or more, from the viewpoint of ensuring the adhesion to the inorganic material layer. Is particularly preferable. On the other hand, from the viewpoint of suppressing the invasion of water and oxygen from the surface of the crosslinked resin layer, it is preferably 35 μm or less, more preferably 20 μm or less, and particularly preferably 10 μm or less.

(Method of forming this crosslinked resin layer)
As a method for forming the present crosslinked resin layer, the above-mentioned crosslinkable resin composition may be applied to the surface of the present inorganic layer and crosslinked.

At this time, as a coating method of the crosslinkable resin composition, a conventionally known coating method can be adopted. For example, any method such as a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, a bar coater, and a coating method using a spray can be adopted. It is not limited to these methods.

As a cross-linking method, heating may be performed in the case of thermal cross-linking, and light rays such as ultraviolet rays may be irradiated in the case of photocross-linking. Further, in order to improve water resistance and durability, if necessary, cross-linking by active energy beam irradiation such as electron beam irradiation can be performed.

<Laminated structure of this protective film>
Since the protective film may have a structure in which an inorganic layer and a crosslinked resin layer are laminated in this order on one side (referred to as "front side") of the base film, the back side of the base film or , An "other layer" may be provided between the base film and the inorganic layer, or on the surface side of the crosslinked resin layer.
For example, as in the above embodiment, an anchor layer may be interposed between the base film and the inorganic layer.

<Thickness of this protective film>
By adjusting the overall thickness of the protective film, it is possible to suppress the occurrence of wrinkles while ensuring light transmission. From this point of view, the total thickness of the protective film is preferably 20 μm or more, particularly preferably 23 μm or more or 500 μm or less, particularly 23 μm or more or 250 μm or less, and particularly preferably 23 μm or more or 125 μm or less.

<Characteristics of this protective film>
The protective film can have a water vapor transmittance (WvTR) of 0.060 g / m ² / day or less at a temperature of 40 ° C. and a relative humidity of 90%, preferably 0.040 g / m ² / day or less, among which. Particularly preferably, it can be 0.020 g / m ² / day or less.
As the method for measuring the water vapor transmittance (WvTR), the measuring method performed in the examples described later may be adopted.

In this protective film, the ratio of the water vapor transmission rate on the front side to the water vapor transmission rate on the back side can be further set to less than 0.5.
In this protective film, the "front side" is a protective film having a structure in which an inorganic material layer and a crosslinked resin layer are laminated in this order on one side of the base film (1), and the crosslinked resin layer side. The "back side" means the base film (1) side.
Some of the protective films that have been used conventionally have a difference of more than twice the water vapor transmittance depending on whether the measurement surface is the front side or the back side, and the direction of the film surface to which the protective film is attached is always limited. It was inconvenient because it was sometimes done.
On the other hand, as described above, if the ratio of the water vapor transmittance on the front side / the water vapor transmittance on the back side is less than 0.5, the direction of the film surface to which the protective film is attached does not matter, that is, the front and back sides. It can be preferably used regardless of the direction of.

<Manufacturing method of this protective film>
As an example of the method for producing the protective film, an anchor layer is formed on one side of the base film as needed, the inorganic layer is formed on the surface of the anchor layer, and then the surface of the inorganic layer is water-soluble. Alternatively, a method of applying and cross-linking a cross-linking resin composition containing a water-dispersible binder resin, a water-soluble alkaline earth metal compound or a water-soluble alkali metal compound, and a curing agent or a cross-linking initiator to form a cross-linked resin layer. Can be mentioned. However, the method is not limited to this method.

The anchor layer can be formed by applying the above-mentioned anchor coating agent to one side of the base film and drying it if necessary.
As described above, the inorganic layer is formed by, for example, a physical vapor deposition (PVD) method, a plasma-assisted vapor deposition method, a chemical vapor deposition (CVD) method, or a method in which inorganic particles are dispersed in an organic polymer and applied. Can be formed by

Then, a crosslinkable resin composition containing a water-soluble or water-dispersible binder resin, a water-soluble alkaline earth metal compound or a water-soluble alkali metal compound, a curing agent or a cross-linking initiator, and a solvent on the surface of the formed inorganic material layer. May be applied and crosslinked to form a crosslinked resin layer.
By forming the main crosslinked resin layer in this way, alkaline earth metal ions or alkali metal ions can be present in the main crosslinked resin layer. Then, the alkali metal ion or the alkali metal ion in the crosslinked resin layer can diffuse and permeate into the adjacent present inorganic layer, and the alkaline earth metal ion or the alkali metal ion can be present in the present inorganic layer.

<< This film laminate >>
Next, as an example of the embodiment using the present protective film, a film laminate using the present protective film (referred to as “the present film laminate”) will be described.

As an example of the present film laminate, on the surface of the present crosslinked resin layer of the laminated film having a structure in which the present inorganic layer and the present crosslinked resin layer are sequentially laminated on at least one side of the present protective film, that is, the base film (1). , A film laminate having a structure in which a base film (2) is bonded to each other via an adhesive layer can be mentioned.

Further, as another example of the present film laminate, a film laminate having a structure in which the laminated film (1) is bonded to the surface of the main crosslinked resin layer of the present protective film via an adhesive layer is formed. Can be done.

At this time, as an example of the laminated film (1), a laminated film having a crosslinked resin layer on one side of the base film (2) can be mentioned.
Further, as another example of the laminated film (1), a laminated film having a structure in which an inorganic material layer and a crosslinked tree species layer are laminated in this order on one side of the base film (2) can be mentioned.
Further, as a further example of the laminated film (1), a laminated film having a structure in which an anchor layer, an inorganic substance layer, and a crosslinked tree species layer are laminated in this order on one side of the base film (2) can be mentioned. ..

The base film (2), anchor layer, inorganic layer and crosslinked tree species layer of the laminated film (1) are all the same as the base film (1), anchor layer, inorganic layer and crosslinked tree species layer of the present protective film. It is preferable to have it.

Further, the adhesive layer of the present film laminate can be formed by using a known adhesive composition. From the viewpoint of achieving both adhesiveness and barrier property, it is preferable to use an adhesive composition containing a binder resin and a curing agent or a cross-linking initiator. As the binder resin, for example, a water-soluble epoxy resin or a water-dispersible polyurethane resin is used. , Water-dispersed urethane acrylate oligomer or the like is preferably used.

<Thickness of this film laminate>
By adjusting the overall thickness of the film laminate, it is possible to suppress the occurrence of wrinkles while ensuring light transmission. From this point of view, the total thickness of the present film laminate is preferably 40 μm or more, particularly preferably 50 μm or more or 500 μm or less, and particularly preferably 50 μm or more or 250 μm or less, particularly 50 μm or more or 125 μm or less.

<Characteristics of this film laminate>
This form laminates temperature 40 ° C., water vapor permeability at 90% relative humidity the (WVTR) can be less 0.060g ^/ m 2 ^/ day, preferably not more than 0.040g ^/ m 2 ^/ day, the Above all, it is particularly preferable that the temperature is 0.0202 g / m ² / day or less.
As the method for measuring the water vapor transmittance (WvTR), the measuring method performed in the examples described later may be adopted.

<< Applications of this protective film and this film laminate >>
The protective film and the film laminate are used for applications that require blocking of various gases such as water vapor and oxygen, for example, for packaging materials that require blocking of various gases, for example, for preventing deterioration of foods, industrial products, pharmaceuticals, and the like. It can be widely used as a packaging material. In addition to packaging applications, it is suitable for various members such as liquid crystal display elements, solar cells, electromagnetic wave shields, touch panels, EL substrates, and color filters.

<< Explanation of words >>
In the present invention, the term "film" shall include the "sheet", and the term "sheet" shall include the "film".
Further, when the term "panel" is used, such as an image display panel, a protective panel, etc., it includes a plate body, a sheet, and a film.

In the present invention, when "X to Y" (X, Y are arbitrary numbers) is described, it means "X or more and Y or less" and "preferably larger than X" or "preferably Y", unless otherwise specified. It also includes the meaning of "smaller".
Further, when "X or more" (X is an arbitrary number) is described, it includes the meaning of "preferably larger than X" and is described as "Y or less" (Y is an arbitrary number) unless otherwise specified. In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the following examples.
The measurement method and evaluation method used in the present invention are as follows.

(1) Film thickness of the inorganic layer formed by the vacuum vapor deposition method (PVD) The film thickness of the inorganic layer was measured by 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. The number (amount) of atoms is known by measuring the emitted fluorescent X-ray intensity. Can be done. Specifically, thin films of two known thicknesses were formed on the film, specific fluorescent X-ray intensities emitted from each were measured, and a calibration curve was created from this information. Then, the fluorescence X-ray intensity of the measurement sample was measured in the same manner, and the film thickness was measured from the calibration curve.

(2) Water vapor permeability (WvTR)
Urethane adhesive [AD900 and CAT-RT85 manufactured by Toyo Morton Co., Ltd. mixed at a ratio of D900: CAT-RT85 = 10: 1.5 (weight ratio)] on the surface of a PET film with a thickness of 50 μm] Was then dried and dried to form an adhesive layer with a thickness of about 3 μm.
On this adhesive layer, the inorganic thin film layer side of the protective film (sample) is laminated so as to be adjacent to the adhesive layer, and (front side) PET film / adhesive layer / crosslinked resin layer / PVD inorganic material layer / anchor coat layer. / A sample film for evaluating water vapor permeability, which has a structure of a base film (back side), was obtained.
The sample film is cut into 10.0 cm x 10.0 cm squares, placed in a constant temperature and humidity device with a temperature of 40 ° C and a relative humidity of 90%, and at intervals of 48 hours or more, up to 14 days as a guideline for the weight increase to become almost constant. The mass was measured (in units of 0.1 mg), and the water vapor permeability on the front side and the back side was calculated from the following formulas, respectively. The front side indicates the side surface of the PET film in the sample film for evaluating the water vapor transmittance, and the back side indicates the side surface of the base film.
Then, if the measured water vapor transmittance (WvTR) is 0.060 g / m ² / day or less, it is evaluated as “○ (good)”, and if it is higher than 0.060 g / m ² / day, it is “x (poor)”. ) ”.

Water vapor permeability [g / m ² / day] = (m / s) / t
m; Increased mass (g) of the last two weighing intervals during the test period
s; Moisture permeability area (m ² )
t; Time (h) / 24 (h) of the last two weighing intervals during the test period

<Example 1>
Anchor layer composition prepared as follows on a biaxially stretched polyethylene terephthalate film F1 (“Diafoil T602E type” manufactured by Mitsubishi Chemical Corporation, thickness 23 μm, referred to as “polyester film F1”) as a base film. The material was applied so that the coating amount (after drying) was 0.025 g / m ² , and dried to form an anchor layer.

(Preparation of anchor coating agent composition)
An isocyanate compound (“Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.) and saturated polyester (“Byron 300” manufactured by Toyo Spinning Co., Ltd., number average molecular weight 23,000) are blended in a 1: 1 mass ratio to form an anchor coating agent. Was prepared.

(PVD inorganic layer formation)
Then, using a vacuum evaporation apparatus, SiO (purity 99.9% or higher) was evaporated in a heating system, by introducing oxygen, an oxygen partial pressure of ^{3.5 × 10 -3 Pa, 5 ×} 10 - ^A PVD inorganic layer (also referred to as “inorganic layer”) made of silicon oxide having a thickness of 40 nm was formed on the anchor layer under a vacuum of ³ Pa.
At this time, in the process of forming the PVD inorganic layer, oxygen gas was introduced into the inorganic layer by using the plasma assist method in combination.

(Formation of Crosslinked Resin Layer 1)
Next, the crosslinkable resin composition 1 prepared as described below is applied to the surface of the inorganic layer by a bar coat method, and then dried with hot air at 80 ° C. for 60 seconds to a thickness (after drying) of 3 g / m. The crosslinked resin layer 1 of No. ² was formed to obtain a protective film (sample) composed of the polyester film F1 / anchor layer / PVD inorganic layer / crosslinked resin layer 1.

(Preparation of Crosslinkable Resin Composition 1)
Binder resin: Modified polyurethane resin
(LIS-7390 manufactured by Toyo Morton Co., Ltd.) 15 parts by mass
Hardener: Bisphenol A type liquid epoxy resin
(LCR-1901 manufactured by Toyo Morton Co., Ltd.) 1 part by mass
Additive: Sodium chloride (water-soluble alkali metal compound)
Solvent: (3% by mass concentration sodium chloride aqueous solution): Isopropyl alcohol
= 3: 97 (mass%) 47.7 parts by mass The concentration was adjusted to 13% by mass by the above formulation.

<Example 2> to <Example 11>
As described in the table, a protective film (sample) was obtained by producing in the same manner as in Example 1 except that the type of the crosslinkable resin composition 1 was changed.
The crosslinkable resin compositions 2, 3, 5 and 6 are the same as those of the crosslinkable resin composition 1 except that the type of the additive (water-soluble alkali metal compound or water-soluble alkaline earth metal compound) is changed. It is prepared. As long as the types of additives (water-soluble alkali metal compounds) were the same, the crosslinkable resin composition having the same name was used even if the amounts of the additives were different.
The crosslinkable resin composition 4 was prepared in the same manner as the crosslinkable resin composition 1 except that no additive was added.

<Comparative example 1>
Manufactured in the same manner as in Example 1 except that the crosslinkable resin layer 1 is not provided and the surface of the PVD inorganic layer surface is not pretreated with an aqueous sodium chloride solution, and is protected by a polyester film F1 / anchor layer / PVD inorganic layer. A film (sample) was prepared.

<Comparative example 2>
A protective film (sample) was obtained in the same manner as in Example 1 except that the crosslinkable resin composition 1 was changed to the crosslinkable resin composition 4 in Example 1.
The crosslinkable resin composition 4 was prepared in the same manner as the crosslinkable resin composition 1 except that no additive (water-soluble alkali metal compound) was added.

<Evaluation result>
The characteristics of each protective film obtained in the above Examples and Comparative Examples are shown in Table 1 below.

In Table 1, PVA: polyvinyl alcohol, EMAA: ethylene methacrylate copolymer, and AAPH: 2,2'-azobis (2-amidinopropane) dihydrochloride are shown.

<Discussion>
It was found that the protective films of Comparative Examples 1 and 2 did not reach the desired level of gas barrier property (water vapor permeability).
Further, as in Comparative Example 2, when the crosslinked resin layer does not contain an additive, it exists while absorbing moisture under high humidity, so that the moisture permeates the inorganic layer and exists in the inorganic layer. It is highly probable that the gas barrier performance deteriorated as a result of water entering the voids of the crystal structure.
Further, the protective film (Comparative Example 1) in which the inorganic layer formed by additionally introducing oxygen gas is exposed (without the crosslinked resin layer) does not reach the desired level of gas barrier property (water vapor permeability). I also understood.

On the other hand, it was found that the protective films of Examples 1 to 11 can reach a desired level of gas barrier property (water vapor permeability). The protective films of Examples 1 to 11 are provided with an inorganic material layer and a crosslinked resin layer on one side of the base film, and the crosslinked resin layer three-dimensionally constructs a crosslinked network structure to allow moisture to enter. Can be prevented and stable gas barrier properties can be exhibited.

Further, in the protective films of Examples 1 to 11, a crosslinked resin composition containing a water-soluble alkali metal compound or a water-soluble alkali metal compound is crosslinked to form a crosslinked resin layer, and the crosslinked resin layer is made of alkaline soil. It was found that the gas barrier property can be further enhanced by containing a similar metal ion or an alkali metal ion.
From the results of such examples and the test results conducted by the present inventor so far, it was found that the presence of alkaline earth metal ions or alkali metal ions in the crosslinked resin layer improves the gas barrier performance. It was. This is because when an alkaline earth metal ion or an alkali metal ion is present in the crosslinked resin layer, the alkaline earth metal ion or the alkali metal ion diffuses and permeates into the adjacent inorganic layer, and the crystal structure exists in the inorganic layer. It can be presumed that the gas barrier property is enhanced as a result of invading gaps such as voids, cracks, and defects. Therefore, it was found that the gas barrier property can be enhanced if the crosslinked resin layer contains alkaline earth metal ions or alkali metal ions.
In particular, it was found that the alkali metal ion had a better result as a gas barrier effect.

The protective film and film laminate of the present invention can be widely used for packaging articles that require blocking of various gases such as water vapor and oxygen, for example, as a packaging material for preventing deterioration of foods, industrial products, pharmaceuticals, and the like. it can. In addition to packaging applications, it can also be suitably used for various members such as liquid crystal display elements, solar cells, electromagnetic wave shields, touch panels, EL substrates, and color filters.

Claims (17)

A protective film having a structure in which an inorganic material layer and a crosslinked resin layer are laminated in this order on one side of the base film (1), and the crosslinked resin layer contains an alkaline earth metal ion or an alkali metal ion. Protective film. The protective film according to claim 1, wherein the water vapor transmittance (WvTR) at a temperature of 40 ° C. and a relative humidity of 90% is 0.060 g / m ² / day or less. The protective film according to claim 1 or 2, wherein the base film (1) is a polyester film. The protective film according to any one of claims 1 to 3, wherein the crosslinked resin layer has a thickness of 1 μm to 35 μm. The crosslinked resin layer is any of claims 1 to 4, wherein the crosslinked resin layer is a layer having a crosslinked resin structure in which a crosslinkable resin composition containing an alkaline earth metal ion or an alkali metal ion, a water-soluble or water-dispersible binder resin is crosslinked. Protective film described in Crab. The protective film according to any one of claims 1 to 5, wherein the alkali metal ion is sodium ion and / or potassium ion, or the alkaline earth metal ion is magnesium ion and / or calcium ion. The protection according to any one of claims 1 to 6, wherein the alkali metal ion is an ion derived from a water-soluble alkali metal compound, or the alkaline earth metal ion is an ion derived from a water-soluble alkaline earth metal compound. the film. The crosslinkable resin composition contains 0.0001 parts by mass to 5.0 parts by mass of a water-soluble alkaline earth metal compound or a water-soluble alkali metal compound with respect to 100 parts by mass of the binder resin, claims 5 to 7. The protective film described in any of. The water-soluble alkali metal compound is at least one selected from sodium hydroxide, sodium chloride, potassium hydroxide and potassium chloride, or the water-soluble alkaline earth metal compound is magnesium chloride and water. The protective film according to claim 7 or 8, wherein the protective film is at least one selected from calcium oxide. In the method for producing a protective film in which an inorganic material layer and a crosslinked resin layer are sequentially formed on one side of the base film (1).
A protective film for forming a crosslinked resin layer by applying and crosslinking a crosslinkable resin composition containing a water-soluble or water-dispersible binder resin, a water-soluble alkaline earth metal compound or a water-soluble alkali metal compound. Production method. The method for producing a protective film according to claim 10, wherein the crosslinkable resin composition contains water and / or alcohol as a main solvent. Claim 10 or 11 that the crosslinkable resin composition contains 0.0001 parts by mass to 5.0 parts by mass of a water-soluble alkaline earth metal compound or a water-soluble alkali metal compound with respect to 100 parts by mass of a binder resin. The method for producing a protective film according to. The method for producing a protective film according to any one of claims 10 to 12, wherein oxygen gas is introduced into the inorganic layer by a plasma-assisted thin-film deposition method. A film laminate having a structure in which a base film (2) is bonded to the surface of a crosslinked resin layer of the protective film according to any one of claims 1 to 9 via an adhesive layer. The crosslinked resin layer of the protective film provided with the base film (2) and the crosslinked resin layer is bonded to the surface of the crosslinked resin layer of the protective film according to any one of claims 1 to 9 via an adhesive layer. A film laminate with a structure consisting of 15. The protective film provided with the base film (2) and the crosslinked resin layer has a structure in which the base film (2), the inorganic material layer and the crosslinked tree species layer are laminated in this order. The film laminate according to the description. The film laminate according to any one of claims 14 to 16, wherein the base film (2) is a polyester film.