JP7149080B2 - Laminated films, packaging materials, packaging bags and packages - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminated film, packaging material, packaging bag and package. In particular, it relates to a laminated film, a packaging material, a packaging bag and a package having controlled water vapor permeability.

Various developments have been made on barrier films (films with low gas permeability) intended for packaging articles such as foods, pharmaceuticals, and electronic parts that are subject to deterioration over time and storage stability.
For example, in Patent Document 1, a film ( A three-layer film of a polymeric film substrate, an aluminum vapor-deposited layer and a polyvinylidene chloride layer) is described.

JP-A-8-39718

As described above, various studies have been made on barrier films.
However, as a result of examination by the present inventors, it was found that the barrier film described in Patent Document 1 does not necessarily have sufficient water vapor barrier properties. Specifically, it was found that when the barrier film was used for a relatively long period of time, the water vapor barrier properties tended to deteriorate over time.

The present invention has been made in view of such circumstances. That is, one of the objects of the present invention is to provide a laminated film in which deterioration of water vapor barrier properties over time is suppressed.

As a result of intensive studies, the inventors have made the following inventions and found that the above objects can be achieved.

The present invention is as follows.
1.
A substrate film layer, an inorganic layer containing metal atoms, a buffer layer made of a material other than polyvinylidene chloride resin, and a polyvinylidene chloride layer containing polyvinylidene chloride resin are laminated in this order,
When the infrared absorption spectrum was measured after the buffer layer was left under conditions of 40 ± 3 ° C. and 7% RH or less for 72 hours, the peak area between 2500 and 3700 cm ^-1 , the peak area between 1000 and 1600 cm ^-1 Let A be the peak area ratio obtained by dividing by
When the infrared absorption spectrum was measured after the buffer layer was left at 40 ± 3 ° C. and 90 ± 5% RH for 72 hours, the peak area between 2500 and ³⁷⁰⁰ cm ^-1 When the peak area ratio obtained by dividing by the area is B,
A laminated film having a B/A of 1.40 or less.
2.
1. A laminated film according to
The laminated film, wherein the buffer layer contains at least one selected from the group consisting of a thermoplastic resin, a thermosetting resin, a reaction product of a silane coupling agent, a metal atom-containing compound, and a cured product of an active energy ray-curable resin. .
3.
2. A laminated film according to
The buffer layer contains a thermoplastic resin,
A laminated film, wherein the thermoplastic resin contains at least one selected from the group consisting of polyester resins, polyurethane resins, ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers and acrylic resins.
4.
2. A laminated film according to
The buffer layer contains a thermosetting resin,
A laminated film, wherein the thermosetting resin contains at least one selected from the group consisting of phenol resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, polyurethane resins and thermosetting polyimide resins.
5.
2. A laminated film according to
The buffer layer contains a cured product of an active energy ray-curable resin,
A laminated film, wherein the active energy ray-curable resin contains at least one selected from the group consisting of urethane acrylate, epoxy acrylate, polyester acrylate and polyether acrylate.
6.
2. A laminated film according to
The buffer layer contains a metal atom-containing compound,
A laminate film, wherein the metal atom-containing compound contains at least one selected from the group consisting of aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, and zirconium oxide.
7.
1. ~6. The laminated film according to any one of
The laminated film, wherein the buffer layer is a vapor-deposited metal layer having a thickness of 1 nm or more and containing at least one of aluminum oxide, silicon oxide, silicon nitride and silicon oxynitride.
8.
1. ~6. The laminated film according to any one of
A laminated film in which the buffer layer is formed of a layer other than a metal deposition layer and having a thickness of 0.1 μm or more.
9.
1. ~8. The laminated film according to any one of
The laminated film, wherein the inorganic layer containing metal atoms contains at least one selected from the group consisting of aluminum, aluminum oxide, silicon oxide, silicon oxynitride and silicon nitride.
10.
1. ~ 9. The laminated film according to any one of
A laminated film in which the base film layer contains a thermoplastic resin.
11.
1. ~ 10. A packaging material using the laminated film according to any one of.
12.
11. A package in which an article is packaged using the packaging material according to 1.
13.
1. ~ 10. A packaging bag made of the laminated film according to any one of
Water vapor permeability from the outer surface side to the inner surface side of the packaging bag when calcium chloride is put in the packaging bag, sealed, and placed in an environment with a temperature of 40 ± 2 ° C and a humidity of 90 ± 5% RH for 168 hours. is 0.65 [g/m ² day] or less,
A food with a water activity of 0.90 is put in the packaging bag, sealed, and placed in an environment with a temperature of 40 ± 2 ° C and a humidity of 7 ± 3% RH for 168 hours, from the inner surface side to the outer surface of the packaging bag. A packaging bag having a water vapor permeability to the side of 1.0 [g/m ² ·day] or less.

ADVANTAGE OF THE INVENTION According to this invention, the laminated|multilayer film whose barrier property of water vapor|steam was suppressed with time is provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for demonstrating the layer structure of the laminated|multilayer film (laminated film 1) of this embodiment. 1 is a diagram for explaining a package 20 composed of a packaging bag 21 made using a laminated film 1 and articles 22 accommodated inside the packaging bag 21. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings, the same constituent elements are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.
In order to avoid complication, (i) when there are a plurality of the same components in the same drawing, only one of them is given a reference numeral and not all of them, and (ii) in particular the figure 2 onward, the same constituent elements as those in FIG. 1 may not be denoted by reference numerals.
All drawings are for illustration purposes only. The shape and dimensional ratio of each member in the drawings do not necessarily correspond to the actual article.

In this specification, the notation "a to b" in the description of numerical ranges means from a to b, unless otherwise specified.
In the description of a group (atomic group) in the present specification, a description without indicating whether it is substituted or unsubstituted includes both those having no substituent and those having a substituent. For example, the term “alkyl group” includes not only alkyl groups without substituents (unsubstituted alkyl groups) but also alkyl groups with substituents (substituted alkyl groups).
The notation "(meth)acryl" used herein represents a concept that includes both acryl and methacryl. The same applies to similar notations such as "(meth)acrylate".

<Laminated film>
FIG. 1 is a diagram showing the layer structure of a laminated film 1 of this embodiment.
The laminated film 1 includes a base film layer 11, an inorganic layer 12 containing metal atoms, a buffer layer 13 made of a material other than polyvinylidene chloride resin, and a polyvinylidene chloride layer 14 containing polyvinylidene chloride resin. They are laminated in this order.
Here, when the infrared absorption spectrum is measured after the buffer layer 13 is left under conditions of 40±3° C. and 7% RH or less for 72 hours, the peak area between 2500 and ^{3700 cm −1 is} Let A be the peak area ratio obtained by dividing by the peak area of
When the infrared absorption spectrum was measured after the buffer layer 13 was left under the conditions of 40±3° C. and 90±5% RH for 72 hours, the peak area between 2500 and 3700 cm ⁻¹ and the peak area between 1000 and 1600 cm ⁻¹ were measured. When the peak area ratio obtained by dividing by the area is B,
B/A is 1.40 or less.

In the following description, the inorganic layer 12 containing metal atoms is the "inorganic layer 12", the buffer layer 13 made of a material other than polyvinylidene chloride resin is the "buffer layer 13", and the polyvinylidene chloride resin containing the polyvinylidene chloride resin is "buffer layer 13". The vinylidene layer 14 is also described as "polyvinylidene chloride layer 14".

The present inventor designed the laminated film 1 of the present embodiment based on various studies. Specifically, between the polyvinylidene chloride layer 14 and the inorganic layer 12, a buffer layer 13 having particularly low water absorption (hygroscopicity) was interposed. It is believed that this suppresses deterioration of the water vapor barrier property over time.

In the present embodiment, measurement data of the infrared absorption spectrum of the buffer layer 13 is used as a measure of water absorbency (hygroscopicity) (specifically, B/A described above). Let me explain this.
According to the findings of the present inventors, when the film is allowed to stand still for a certain period of time in a high-humidity environment and the film absorbs moisture, it is thought that the vibration of the water molecules absorbed by the resin causes a temperature difference around 2500 to 3700 cm ⁻¹ . Absorption increases. On the other hand, the absorption around 1000 to 1600 cm ⁻¹ hardly changes (mainly only the absorption peculiar to the film material is observed). Therefore, the value obtained by dividing the former absorption peak area by the latter absorption peak area can be used as an index for the water vapor transmission rate of the film.

In this embodiment,
・When the infrared absorption spectrum was measured after the buffer layer 13 was left under the conditions of 40±3° C. and 7% RH or less for 72 hours, the peak area between 2500 and 3700 cm ⁻¹ and the peak between 1000 and 1600 cm ⁻¹ The peak area ratio obtained by dividing by the area is A,
・When the infrared absorption spectrum was measured after the buffer layer 13 was left under the conditions of 40 ± 3 ° C. and 90 ± 5% RH for 72 hours, the peak area between 2500 and ^{3700 cm -1 was} B, the peak area ratio obtained by dividing by the peak area
, a buffer layer 13 having a B/A of 1.40 or less is provided between the inorganic layer 12 and the polyvinylidene chloride layer 14 . B/A is an index of water vapor permeability, and the larger the B/A, the more water molecules are absorbed by the resin. It is presumed that the water vapor permeability is low because there are few water molecules.
Therefore, the closer B/A is to 1, the better. Specifically, it is more preferably 1.35 or less, further preferably 1.2 or less, and particularly preferably 1.1 or less.

The material, thickness and other properties of each layer of the laminated film 1 will be described.

・Base film layer 11
The material constituting the base film layer 11 is not particularly limited, but typically contains a thermoplastic resin. That is, the base film layer 11 is preferably composed of a sheet-like or film-like base material formed of a material containing a thermoplastic resin.
The base film layer 11 is expected to play a role of making the strength of the laminated film 1 sufficient and allowing the inorganic layer 12 to exist stably.

Specific examples of the thermoplastic resin that the base film layer 11 can contain include polyolefins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyethylene terephthalate (PET); polyesters such as polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon-6, nylon-66 and polymetaxylene adipamide; polyvinyl chloride; polyimide; ethylene/vinyl acetate copolymer; ionomer; and the like.
The thermoplastic resin of the base film layer 11 is preferably polyester such as polyethylene terephthalate (PET), polybutylene terephthalate, or polyethylene naphthalate, and more preferably polyethylene terephthalate.

The base film layer 11 may contain components other than the thermoplastic resin. For example, additives such as anti-fogging agents and anti-blocking agents, adhesive resins such as urethane resins, urea resins, melamine resins, epoxy resins, alkyd resins, and silane coupling agents are included. good too.

The thickness of the base film layer 11 is preferably 5-50 μm, more preferably 8-30 μm. With this thickness, it is possible to obtain the laminated film 1 with good handleability (not bulky) while obtaining sufficient strength.

・Inorganic layer 12
The inorganic substance forming the inorganic layer 12 is not particularly limited as long as it contains a metal atom, and examples thereof include metals and metal oxides. More specifically, periodic table 2A group elements such as beryllium, magnesium, calcium, strontium, and barium; periodic table transition elements such as titanium, zirconium, ruthenium, hafnium, and tantalum; periodic table 2B group elements such as zinc; Periodic table 3B group elements such as gallium, indium and thallium; periodic table 4B group elements such as silicon, germanium and tin; periodic table 6B group elements such as selenium and tellurium. Or two or more types can be mentioned.

Among the inorganic substances, one or more inorganic substances selected from the group consisting of silicon oxide, silicon oxynitride, aluminum oxide, and aluminum are preferable from the viewpoint of barrier properties, cost, and the like. In particular, from the viewpoint of water vapor barrier properties, an aspect containing aluminum atoms such as aluminum and aluminum oxide is preferred, and from the viewpoint of ensuring the transparency of the film, aluminum oxide is preferred.
Silicon oxide may contain silicon monoxide and silicon suboxide in addition to silicon dioxide. Similarly, aluminum oxide includes, in addition to aluminum (III) oxide represented by the chemical formula of Al ₂ O ₃ , aluminum (II) oxide represented by the chemical formula of AlO and oxide represented by the chemical formula of Al ₂ O Aluminum (I) may be included.
The inorganic layer 12 contributes to water vapor barrier properties due to its dense (small gaps) microstructure peculiar to inorganic materials.

The inorganic layer 12 is preferably made of at least one of the above inorganic substances. The inorganic layer 12 may be composed of a single inorganic layer, or may be composed of a plurality of inorganic layers. Further, when the inorganic layer 12 is composed of a plurality of inorganic layers, it may be composed of the same type of inorganic layers, or may be composed of different types of inorganic layers.

A method for forming the inorganic layer 12 is not particularly limited. For example, the inorganic layer 12 can be formed on the surface of the base film layer 11 by a vacuum process such as a vacuum deposition method, a sputtering method, a plasma vapor deposition method (CVD method), a sol-gel process, or the like.

The thickness of the inorganic layer 12 is preferably 1 nm to 500 nm, more preferably 5 nm to 300 nm or less, and more preferably 7 nm to 150 nm. By setting this thickness, it is possible to optimize the balance among sufficient water vapor barrier performance, handling (not bulky), adhesion to other layers, and the like.
In addition, this thickness can be obtained from an image observed by a transmission electron microscope or a scanning electron microscope, for example.

・Buffer layer 13
The buffer layer 13 is not particularly limited as long as it is made of a material other than a polyvinylidene chloride resin (in other words, it does not substantially contain a polyvinylidene chloride resin). Here, "substantially free" means, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 1% by mass or less, and particularly It preferably means that it does not contain at all.
As described above, the provision of the buffer layer 13 can prevent deterioration of the water vapor barrier property of the polyvinylidene chloride layer 14 .

The buffer layer 13 preferably contains at least one selected from the group consisting of a thermoplastic resin, a thermosetting resin, a reaction product of a silane coupling agent, a metal atom-containing compound, and a cured product of an active energy ray-curable resin. . These will be specifically described below.

Specific examples of thermoplastic resins that can be contained in the buffer layer 13 include polyolefin resins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyethylene terephthalate (PET); polyester resins such as butylene terephthalate and polyethylene naphthalate; polyamide resins such as nylon-6, nylon-66 and polymetaxylene adipamide; polyvinyl chloride resins; polyimide resins; polyurethane resins; alcohol copolymer; polyacrylonitrile resin; polycarbonate resin; polystyrene resin;

In particular, the buffer layer 13 may contain, as a thermoplastic resin, at least one resin selected from the group consisting of polyester resins, polyurethane resins, ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, and acrylic resins. preferable. By including these thermoplastic resins in the buffer layer 13, the hygroscopicity of the buffer layer 13 can be easily lowered, and the B/A value described above can be easily designed to be small. In other words, it is considered that when the buffer layer 13 contains these resins, the effect of further improving the vapor barrier property of the laminated film 1 can be obtained.
The buffer layer 13 may contain only one kind of thermoplastic resin, or may contain two or more kinds thereof.

The thermosetting resin that can be included in the buffer layer 13 is at least one selected from the group consisting of phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, polyurethane resin and thermosetting polyimide resin. preferable. These thermosetting resins are considered to be less likely to absorb moisture due to their dense/rigid molecular structure, and are easy to design with a small B/A value. In other words, by designing the buffer layer 13 using these resins, it is believed that the effect of further improving the water vapor barrier property of the laminated film 1 can be obtained.
The buffer layer 13 may contain only one type of thermosetting resin, or may contain two or more types.

The active energy ray-curable resin constituting the buffer layer 13 is not particularly limited, but preferably at least one selected from the group consisting of urethane acrylate, epoxy acrylate, polyester acrylate and polyether acrylate.

The active energy ray-curable resin is usually used in combination with a compound (usually called an initiator) that generates cations, radicals, etc. by irradiation with an active energy ray (typically ultraviolet rays).

Among initiators, photoradical initiators that generate radicals upon irradiation with light include, for example, acetophenone, p-tert-butyltrichloroacetophenone, chloroacetophenone, 2,2-diethoxyacetophenone, hydroxyacetophenone, 2,2- Acetophenones such as dimethoxy-2′-phenylacetophenone, 2-aminoacetophenone, dialkylaminoacetophenone; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy- Benzoins such as 2-methyl-1-phenyl-2-methylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one; benzophenone, benzoylbenzoic acid, benzoyl Benzophenones such as methyl benzoate, methyl-o-benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, hydroxypropylbenzophenone, acrylbenzophenone, 4,4′-bis(dimethylamino)benzophenone; thioxanthone, 2-chlorothioxanthone, 2 - Thioxanthones such as methylthioxanthone, diethylthioxanthone, and dimethylthioxanthone; fluorine-based peroxides such as perfluoro(tert-butyl peroxide) and perfluorobenzoyl peroxide; α-acyloxime ester, benzyl-(o-ethoxycarbonyl)-α-monoxime , acylphosphine oxide, glyoxyester, 3-ketocoumarin, 2-ethylanthraquinone, camphorquinone, tetramethylthiuram sulfide, azobisisobutyronitrile, benzoyl peroxide, dialkyl peroxide, tert-butyl peroxypivalate, etc. can be done. These mainly generate radicals in the UV region with light wavelengths of 200 to 400 nm.

Among the initiators, the photocationic initiator that generates cations upon irradiation with light is not particularly limited as long as it is a compound that initiates the cationic polymerization of the ring-opening polymerizable compounds capable of cationically polymerizing upon irradiation with light. Preferred are compounds that photoreact to release a Lewis acid, such as onium salts of "onium cation-its counteranion". These often exhibit their functions mainly in the UV region where the wavelength of light is 200 to 400 nm or less.
Onium cations include, for example, diphenyliodonium, 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(dodecylphenyl)iodonium, triphenylsulfonium, diphenyl-4 -thiophenoxyphenylsulfonium, bis[4-(diphenylsulfonio)-phenyl]sulfide, bis[4-(di(4-(2-hydroxyethyl)phenyl)sulfonio)-phenyl]sulfide, η5-2,4 -(Cyclopentagenyl)[1,2,3,4,5,6-η-(methylethyl)benzene]-iron(1+) and the like. In addition to onium cations, perchlorate ions, trifluoromethanesulfonate ions, toluenesulfonate ions, trinitrotoluenesulfonate ions, and the like can be used.
On the other hand, counter anions include, for example, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate, tetra(fluorophenyl)borate, tetra(difluorophenyl)borate, tetra(trifluorophenyl ) borate, tetra(tetrafluorophenyl)borate, tetra(pentafluorophenyl)borate, tetra(perfluorophenyl)borate, tetra(trifluoromethylphenyl)borate, tetra(di(trifluoromethyl)phenyl)borate, etc. can be done.

Metal oxides such as aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, and zirconium oxide are preferable examples of the metal atom-containing compound that the buffer layer 13 can contain. In this specification, silicon (Si) is treated as a metal element.
The metal atom-containing compound that the buffer layer 13 can contain is typically amorphous. In addition, when the buffer layer 13 contains a compound such as a metal oxide, its oxidation state is not particularly limited as long as it is stable under the normal use conditions of the packaging bag 21, and a chemical compound whose composition is theoretically stable. It does not have to follow a stoichiometric ratio (e.g. aluminum oxide does not have to be perfect Al ₂ O ₃ ).
The buffer layer 13 may contain only one kind of metal atom-containing compound, or may contain two or more kinds thereof.

When the buffer layer 13 contains a metal atom-containing compound, the method of providing the buffer layer 13 is not particularly limited, but a preferred example is a sol-gel method. The sol-gel method is expected to have advantages such as simpler steps and easier control of the properties of the buffer layer 13 than other methods (gas phase process, etc.).
Specifically, the metal alkoxide represented by the formula: M (OR) _n (M represents Si, Ti, Ai or Zr, R represents an alkyl group having 1 to 3 carbon atoms, n is 3 or 4 It is conceivable to provide the buffer layer 13 by performing dehydration condensation or the like by a known sol-gel technique using an appropriate raw material liquid containing the sol-gel method.
Moreover, the buffer layer 13 may be formed of a metal deposition layer containing at least one of aluminum oxide, silicon oxide, silicon nitride, and silicon oxynitride.

When the buffer layer 13 contains a compound containing a metal atom, the layer containing the metal atom is continuous together with the inorganic layer 12 . Although this embodiment does not exclude the aspect in which the inorganic layer 12 and the buffer layer 13 have the same composition, it is preferable that the inorganic layer 12 and the buffer layer 13 have different compositions from the viewpoint of the effect.

Examples of silane coupling agents that can be used as raw materials for the buffer layer 13 include aminosilane, epoxysilane, acrylsilane, mercaptosilane, vinylsilane, ureidosilane, and sulfidesilane.

Examples of aminosilanes include bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-amino propylmethyldimethoxysilane, N-β (aminoethyl)γ-aminopropyltrimethoxysilane, N-β (aminoethyl)γ-aminopropyltriethoxysilane, N-β (aminoethyl)γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldiethoxysilane, N-phenyl-γ-amino-propyltrimethoxysilane, and the like.
Examples of epoxysilanes include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and γ-glycidylpropyltrimethoxysilane. Silane etc. are mentioned.
Examples of acrylic silanes include γ-(methacryloxypropyl)trimethoxysilane, γ-(methacryloxypropyl)methyldimethoxysilane, γ-(methacryloxypropyl)methyldiethoxysilane, and the like.
Mercaptosilanes include, for example, 3-mercaptopropyltrimethoxysilane.
Vinylsilanes include, for example, vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, and the like.
Ureidosilanes include, for example, 3-ureidopropyltriethoxysilane.
Examples of sulfide silanes include bis(3-(triethoxysilyl)propyl)disulfide and bis(3-(triethoxysilyl)propyl)tetrasulfide.

In addition, the silane coupling agent is a buffer layer between the inorganic layer 12 and the polyvinylidene chloride layer 14 from the point that it is known as its property "to be interposed between an organic substance and an inorganic substance to increase adhesion". 13, the adhesion between layers is improved, and effects such as improved durability of the laminated film and further improved water vapor barrier performance are considered to be obtained.

Although the lower limit of the thickness of the buffer layer 13 is not particularly limited, it is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. It is considered that the effect of the buffer layer 13 can thus be sufficiently obtained. In particular, as one aspect, it is preferable that the buffer layer consists of a layer other than the metal vapor deposition layer having a thickness of 0.1 μm or more.
The upper limit of the thickness of the buffer layer 13 is also not particularly limited, but it is preferably 5.0 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less. This makes it possible to obtain the laminated film 1 with good handleability (not bulky).
Furthermore, when the buffer layer 13 is formed of a vapor-deposited metal layer containing at least one of aluminum oxide, silicon oxide, silicon nitride, and silicon oxynitride, the upper and lower limits of its thickness are not particularly limited. From the viewpoint of ensuring sufficient properties, the thickness is, for example, 1 nm or more, preferably 1 to 50 nm, more preferably 5 to 30 nm, and still more preferably 7 to 15 nm.

・Polyvinylidene chloride layer 14
Polyvinylidene chloride is known as a resin having a considerably low water vapor permeability among general-purpose synthetic resins when made into a film. In other words, the polyvinylidene chloride layer 14 is considered to play an important role in developing water vapor barrier properties in combination with other layers (such as the inorganic layer 12).
The polyvinylidene chloride layer 14 is not particularly limited as long as it contains a polyvinylidene chloride resin. Here, the "polyvinylidene chloride resin" is not particularly limited as long as it contains a structural unit corresponding to a vinylidene chloride monomer, and may be polyvinylidene chloride (PVDC), vinylidene chloride, and vinylidene chloride. It may be a copolymer with another monomer copolymerizable with.
The polyvinylidene chloride layer 14 preferably contains 80% by mass or more of the polyvinylidene chloride resin, more preferably 90% by mass or more.

As the copolymer, the content ratio of vinylidene chloride is 60% by mass or more and 99% by mass or less, and the content ratio of a monomer copolymerizable with vinylidene chloride is 1% by mass or more and 40% by mass or less. You can raise the coalescence. Examples of monomers copolymerizable with vinylidene chloride include vinyl chloride, (meth)acrylonitrile, (meth)acrylic acid, (meth)acrylic acid alkyl ester (alkyl group having 1 to 18 carbon atoms), and maleic anhydride. , itaconic acid, itaconic acid alkyl ester, vinyl acetate, ethylene, propylene, isobutylene, butadiene, and the like.
The polyvinylidene chloride-based resin may be obtained by producing it by a known method, or various commercially available products may be used. Commercially available products include Saran resin series manufactured by Asahi Kasei Corporation.

As an example, the form of polyvinylidene chloride resin is preferably in the form of latex (aqueous emulsion) containing fine particles of polyvinylidene chloride resin. As a result, an effect such as an antistatic effect (suppression of static electricity) of the laminated film 1 can be expected.
In this case, from the viewpoint of stabilizing the water vapor barrier performance, a polyvinylidene chloride resin dissolved in an organic solvent is coated between the inorganic layer 12 and a latex layer containing fine particles of polyvinylidene chloride resin. It is preferable to provide a layer containing a vinylidene chloride resin.
This latex may be produced by a conventionally known method, or various commercial products may be used. Commercially available products include Saran latex series manufactured by Asahi Kasei Corporation.

The polyvinylidene chloride layer 14 may contain components other than the polyvinylidene chloride resin. For example, additives similar to those of the base film layer 11, adhesive resins, and components that improve film-forming properties (eg, silane coupling agents, surfactants, antifoaming agents, leveling agents, etc.) may be included. .

The method of forming the polyvinylidene chloride layer 14 using the polyvinylidene chloride resin as a raw material is not particularly limited.
For example, the polyvinylidene chloride layer 14 can be formed by dissolving a polyvinylidene chloride resin in an organic solvent, applying the solution to the surface of the buffer layer 13, and drying it. The organic solvent that can be used at this time is not particularly limited because it is appropriately selected according to the type of polyvinylidene chloride resin to be used. For example, ketones such as acetone, methyl ethyl ketone and cyclohexanone; ethers such as dioxane, diethyl ether and tetrahydrofuran; aromatic hydrocarbons such as benzene, toluene and xylene; esters such as ethyl acetate and butyl acetate; amides; mixed solvents thereof; and the like. Among these, a mixed solvent of tetrahydrofuran and toluene, a mixed solvent of methyl ethyl ketone and toluene, and a mixed solvent of tetrahydrofuran, toluene and methyl ethyl ketone are preferable. Polyvinylidene chloride layer 14 can be formed using polyvinylidene chloride dissolved in an organic solvent as described above.
Alternatively, the polyvinylidene chloride layer 14 may be formed by applying a latex containing fine particles of a polyvinylidene chloride resin to the surface of the buffer layer 13 and drying it.

Furthermore, as described above, the polyvinylidene chloride layer 14 is formed on the surface of the buffer layer 13 by using polyvinylidene chloride dissolved in an organic solvent, and the polyvinylidene chloride layer is formed by latex containing fine particles of polyvinylidene chloride resin. 14 may be both formed to form a two-layer polyvinylidene chloride layer 14 .
Particularly in this case, it is preferable to form the layer on the buffer layer 13 side of the two layers using an organic solvent. This is because (1) the adhesion to other layers can be enhanced by forming layers using an organic solvent, and (2) polyvinylidene chloride in latex form is generally inexpensive, and surfactants are not required. The reason for this is that it is excellent in antistatic property in the manufacturing process and the adhesion of dust is suppressed by including it.

The thickness of the polyvinylidene chloride layer 14 is preferably 0.05-20 μm, more preferably 0.1-10 μm, and still more preferably 0.2-5 μm. It should be noted that when the polyvinylidene chloride layer 14 includes multiple layers (for example, when the layers are formed using both the organic solvent-based and the latex-based layers described above), the total thickness of the multiple layers is the thickness shown here. Preferably.
With this thickness, it is possible to obtain the laminated film 1 that has sufficient water vapor barrier properties and is easy to handle (not bulky).

- Other Layers The laminated film 1 may further have layers other than the four layers described above. For example, it may have a heat-sealing layer for enhancing heat-sealing properties, a protective layer for protecting the laminated film 1 from external force and contact with contents, a lubricating layer, an antistatic layer, and the like. Moreover, these layers may be provided by coating or may be provided by lamination.

As an example, from the viewpoint of imparting heat-sealing properties, homopolymers or copolymers of α-olefins such as ethylene, propylene, butene-1, hexene-1, 4-methyl-1-pentene, and octene-1, high-density polyethylene, medium Polyethylene such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, homopolypropylene, random copolymer of propylene and α-olefin having 2 or 4 to 10 carbon atoms, low crystallinity or amorphous A layer formed of a resin composition containing one or more polyolefins selected from ethylene/propylene random copolymers, etc., a layer formed of a resin composition containing an ethylene/vinyl acetate copolymer (EVA) , a layer formed of a resin composition containing EVA and polyolefin, and the like can be additionally provided. Among these, α-olefin homopolymers or copolymers are preferred.

- Manufacturing method of laminated film 1 Although the manufacturing method has been appropriately described in the description of each component, it will be described again.
The production method may be any method, but the production can preferably be carried out according to the following procedure.

(1) Prepare a substrate constituting the substrate film layer 11, for example, a film containing a thermoplastic resin such as a PET film.
This film may be subjected to a surface treatment such as corona treatment, plasma treatment, undercoat treatment, primer coat treatment, flame treatment, etc., in order to increase the adhesiveness with the inorganic layer 12 .

(2) forming the inorganic layer 12;
Examples of the formation method include a method of forming on the surface of the base film layer 11 by a vacuum process such as a vacuum deposition method, a sputtering method, a plasma vapor deposition method (CVD method), and a formation method by a so-called sol-gel method. be done.

(3) forming a buffer layer 13;
For example, one or more of the above-mentioned thermoplastic resins, thermosetting resins, silane coupling agents, metal atom-containing compounds, etc. are dissolved in a solvent and coated on the inorganic layer 12, After that, the solvent is volatilized, and the buffer layer 13 can be formed by, for example, heating as necessary (depending on the material used, the chemical reaction proceeds by heating).
In addition, the buffer layer 13 is formed by coating the inorganic layer 12 with the active energy ray-curable resin dissolved in a solvent, then volatilizing the solvent, and irradiating the active energy ray. You can also At this time, ultraviolet rays (UV) are preferable as active energy rays. The amount of active energy ray irradiation (accumulated amount of light) is, for example, about 10 to 1000 mJ/cm ² .
Alternatively, the buffer layer 13 may be formed by a sol-gel method or the like. Specifically, a buffer layer 13 is formed by applying an appropriate raw material liquid containing a metal alkoxide (such as one represented by the above formula: M(OR) _n ) and subjecting it to dehydration condensation or the like by a known method. may
Alternatively, the buffer layer 13 may be formed by a known lamination method or the like. That is, a single-layer film, which is the base of the buffer layer 13, may be attached to the surface of the inorganic layer 12 by a lamination method such as a heat lamination method or a dry lamination method.

(4) A polyvinylidene chloride resin dissolved in an organic solvent and/or a latex containing fine particles of polyvinylidene chloride resin is applied to the surface of the buffer layer 13 to form a polyvinylidene chloride layer 14. .
The polyvinylidene chloride-based resin material (dissolved in an organic solvent or latex) that can be used here is as described above.

When a polyvinylidene chloride resin dissolved in an organic solvent is applied, the coating amount is usually 0.05 to 5.0 g/m ² , preferably 0.07 to 2.0 g/m ² , more preferably 0.1 to 0.5 g/m ² . Moreover, the thickness (thickness after drying) is usually 0.02 to 3.1 μm, preferably 0.05 to 1.3 μm. These are determined from the viewpoint of the balance of barrier properties, transparency, amount of residual solvent, adhesion, handleability, and the like.

When a latex containing fine particles of a polyvinylidene chloride resin is applied, the coating amount is usually 0.2 to 10.0 g/m ² , preferably 0.5 to 5.0 g/m ² , more preferably 0.5 to 5.0 g/m 2 . 8 to 3.0 g/m ² . The thickness (thickness after drying) is usually 0.1 to 6.2 μm, preferably 0.2 to 1.8 μm. These are determined from the viewpoint of the balance of barrier properties, transparency, amount of residual solvent, adhesion, handleability, and the like.

The coating method and apparatus described above are not particularly limited. For example, the above steps can be carried out using known coating machines such as air knife coaters, kiss roll coaters, metering bar coaters, gravure roll coaters, reverse roll coaters, dip coaters and die coaters.

Moreover, the drying method after coating is not particularly limited. For example, a drying method using a known dryer such as an arch dryer, a straight bath dryer, a tower dryer, a drum dryer, or a floating dryer can be used. The drying temperature is usually 50 to 200°C, preferably 70 to 150°C, more preferably 90 to 130°C. The drying time is usually 5 seconds to 10 minutes, preferably 5 seconds to 3 minutes, more preferably 5 seconds to 1 minute.

After the above drying, it is preferable to perform an aging treatment in an oven or the like, if necessary. For example, the dried film is preferably aged in an oven at 35 to 60° C., more preferably 40 to 50° C. for 24 hours or longer, more preferably 48 to 72 hours. This aging treatment promotes the crystallization of the polyvinylidene chloride resin, thereby further improving the barrier performance.

- Water vapor permeability The laminated film 1 preferably has a water vapor permeability of 0.65 g/m ² ·day or less measured under conditions of 40 ± 2°C and 90 ± 5% RH. When the water vapor transmission rate is less than this value, the effect of preventing the articles packaged with the laminated film 1 from absorbing moisture in the air or suppressing the drying of the articles packed with the laminated film 1 becomes more remarkable. . The water vapor permeability can be measured according to JIS K 7129 using a water vapor permeability measuring device manufactured by MOCON.

In addition, as a measurement under conditions closer to the actual environment (environment in which the laminated film 1 is put into practical use), a packaging bag made of the laminated film 1 (for example, a packaging bag 21 described later) was filled with calcium chloride or water activity. is 0.90, sealed and allowed to stand for a certain period of time, and the water vapor transmission rate can be calculated from the amount of increase/decrease in the mass of the contents and the inner surface area of the packaging bag at this time.
Specifically, calcium chloride was placed in a packaging bag made of the laminated film 1, sealed, and placed in an environment with a temperature of 40 ± 2 ° C and a humidity of 90 ± 5% RH for 168 hours. The water vapor permeability from the surface side to the inner surface side is preferably 0.65 [g/m ² ·day] or less, more preferably 0.55 [g/m ² ·day] or less, and still more preferably 0.50. [g/m ² ·day] or less.
In addition, a food with a water activity of 0.90 is put in a packaging bag made of the laminated film 1, sealed, and placed in an environment with a temperature of 40 ± 2 ° C and a humidity of 7 ± 3% RH for 168 hours. The water vapor transmission rate from the inner surface side to the outer surface side of the bag is preferably 1.0 [g/m ² ·day] or less, more preferably 0.70 [g/m ² ·day] or less, still more preferably It is 0.50 [g/m ² ·day] or less.
By measuring the water vapor transmission rate by leaving the packaging bag in the environment of 40° C. for a long time of 168 hours, it is possible to quantitatively evaluate the degree of “decrease in water vapor barrier properties over time”.

<Packaging bags, packaging materials>
FIG. 2 illustrates a package 20 composed of a packaging bag 21 made using the laminated film 1 and articles 22 housed inside the packaging bag 21. As shown in FIG.
In the packaging body 20, the packaging bag 21 preferably has its opening (right side in FIG. 2) sealed by a suitable means (for example, heat sealing method).

The packaging bag 21 is not particularly limited as long as it is made using the laminated film 1 described above. However, as the knowledge of the present inventor, preferably, which of the base film layer 11 and the polyvinylidene chloride layer 14 of the laminated film 1 is the inner surface side of the packaging bag 21 and which is the outer surface side is appropriately determined. By examining and selecting, it is possible to further suppress the deterioration of the water vapor barrier performance over time.

Specifically, when aiming to suppress moisture absorption (preventing dryness) of the article 22 due to moisture in the air, it is preferable to place the base film layer 11 on the outer surface side and the polyvinylidene chloride layer 14 on the inner surface side. . On the other hand, for the purpose of suppressing drying (moisturizing) of the article 22, it is preferable to place the base film layer 11 on the inner surface side and the polyvinylidene chloride layer 14 on the outer surface side.

The article 22 is not particularly limited, and may be food, medicine, semiconductor elements, electronic parts such as organic EL, and the like. The packaging bag 21 can preferably seal any article for which moisture absorption or drying can be a problem.
If the article 22 is a dry article (an article whose moisture absorption may be a problem), examples of foods include baked goods (cookies, biscuits, etc.), rice crackers, rice crackers, hail, rice crackers such as popped confectionery, vegetable chips, Examples include snacks, furikake, grain powders (wheat flour, rice flour, etc.). Examples of pharmaceuticals include powders, granules, capsules, and tablets.
If the article 22 is an article containing a relatively large amount of moisture (an article that may cause a problem of drying), examples of foods include cakes, bread, cooked rice, and jam. Examples of non-food items include clay (eg clays for handicrafts and crafts), wet wipes (eg wet wipes and makeup remover sheets), wet towels, and the like.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can be adopted. Moreover, the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.

Embodiments of the present invention will be described in detail based on examples and comparative examples. In addition, the present invention is not limited to the examples.

<Example 1: Preparation of laminated film>
(1) Formation of an inorganic layer on a film constituting a base film layer First, as a film constituting a base film layer, a 12 μm-thick biaxially stretched polyethylene terephthalate film (manufactured by Unitika Ltd., trade name: Emblet PET12) ) was prepared. On the corona-treated surface of this film, aluminum was heated and evaporated by a high-frequency induction heating method, oxygen was further introduced, and aluminum oxide was vapor-deposited on the substrate film to a thickness of 7 nm to form an inorganic layer.

(2) Formation of buffer layer
A polyurethane-based coating material was applied onto the inorganic layer (aluminum oxide layer having a thickness of 7 nm) formed in (1) above and dried to form a buffer layer.
Specifically, first, a polyurethane-based coating material (trade name: Takelac WPB341, 30% concentration aqueous solution) manufactured by Mitsui Chemicals, Inc. was diluted with water to 20%. This was applied using an applicator in an amount of 0.3 g/m ² in terms of solid content (that is, applied so that the weight after drying was 0.3 g/m ² ). After the coating, it was dried for 30 seconds using a dryer. A buffer layer was formed as described above.

(3) Formation of polyvinylidene chloride layer A polyvinylidene chloride coating material manufactured by Asahi Kasei Corporation (Saran latex L536B, concentration 50%) was diluted with water to 25% and neutralized with 10% aqueous ammonia. . This was applied onto the buffer layer formed in (2) above. A Meyer bar was used for coating, and the coating amount was adjusted to 1.0 g/m ² (solid content). After coating, it was dried in an oven at 100° C. for 60 seconds. Thus, a polyvinylidene chloride layer was formed.

(4) Formation of heat seal layer and aging treatment A non-stretched polypropylene film (trade name: GLC#40) manufactured by Mitsui Chemicals Tohcello Co., Ltd. was used as an adhesive for the samples prepared in (1) to (3) above. Laminated with a polyvinylidene chloride layer.
As the adhesive, a Mitsui Chemicals urethane-based adhesive (trade name: a mixture of Takelac A-310 and Takenate A-3 at a ratio of 12:1 and diluted with ethyl acetate) was applied to the surface of the unstretched polypropylene film. It was applied with a bar so as to be 3.0 g/m ² (solid content), dried and used.
After lamination, aging was performed in an oven at 40°C for 2 days.
As described above, a film for evaluation was obtained.

<Example 2: Preparation of laminated film>
A laminate film for evaluation was obtained in the same manner as in Example 1, except that the step (2) of Example 1 was changed as follows.
First, a polyester resin (trade name: Elitel UE9800) manufactured by Unitika was dissolved in a 1:1 mixed solvent of ethyl acetate and methyl ethyl ketone to prepare a 5% solution. Then, in the same manner as in Example 1, this solution was applied onto the inorganic layer formed in (1) and dried to form a buffer layer.

<Example 3: Preparation of laminated film>
A laminate film for evaluation was obtained in the same manner as in Example 1, except that the step (2) of Example 1 was changed as follows.
First, an ethylene vinyl alcohol resin (product name: Soarnol 16DX) manufactured by Nippon Gosei Co., Ltd. was dissolved in a 1:1:1 mixed solvent of water, isopropyl alcohol and normal propyl alcohol to prepare an 8% solution. Then, in the same manner as in Example 1, this solution was applied onto the inorganic layer formed in (1) and dried to form a buffer layer.

<Example 4: Preparation of laminated film>
A laminate film for evaluation was obtained in the same manner as in Example 1, except that the step (2) of Example 1 was changed as follows.
First, a UV-curable acrylic resin (product name: Orester RA3050) manufactured by Mitsui Chemicals, Inc. was diluted with ethyl acetate to 7.3%. To this, Irgacure 184 (manufactured by BASF) was added as a photoinitiator in an amount of 8% based on the resin content. Then, this solution was applied onto the inorganic layer formed in (1) in the same manner as in Example 1, and dried.
After that, using a UV irradiation device (EYE GRANDAGE model ECS 301G1 manufactured by Eyegraphic Co., Ltd.), ultraviolet rays were irradiated under the conditions of UV intensity: 210 mW/m ² and integrated light amount: 330 mJ/cm ² . Thereby, the components in the film were polymerized to form a buffer layer.

<Comparative Example 1: Preparation of laminated film>
A laminate film for evaluation was obtained in the same manner as in Example 1, except that the step (2) of Example 1 was changed as follows.
A polyvinyl alcohol resin (trade name: PVA105) manufactured by Kuraray Co., Ltd. was dissolved in water to prepare a 10% aqueous solution. This solution was applied onto the inorganic layer formed in (1) in the same manner as in Example 1 and dried to form a buffer layer.

<Comparative Example 2: Preparation of laminated film>
A laminate film for evaluation was obtained in the same manner as in Example 1, except that the step (2) of Example 1 was changed as follows.
A polyvinylidene chloride resin (trade name: Saran Resin F216) manufactured by Asahi Kasei Corporation was heated and dissolved at 70° C. in a 2:1 mixed solvent of methyl ethyl ketone and toluene to prepare a 5% solution. This solution was applied onto the inorganic layer formed in (1) in the same manner as in Example 1 and dried to form a buffer layer.
That is, two polyvinylidene chloride layers were provided without providing a buffer layer.

<Preparation of packaging bag for evaluation>
The laminated film for evaluation obtained above was made into a bag having an inner surface area of 0.01 m ² (100 cm ² ) to obtain a packaging bag. At this time, the surface of the unstretched polypropylene film laminated by the dry lamination method was made to face the inner surface of the bag.

<Measurement of infrared absorption spectrum of buffer layer>
The infrared absorption spectrum of the buffer layer was measured by the infrared total reflection measurement method (ATR method) to obtain the aforementioned A, B and B/A. These numerical values are listed in Table 1.
Specifically, it was measured as follows.

-Preparation of samples for measurement Two samples for spectrum measurement were prepared by slantingly cutting the laminated film of each example and comparative example with a blade to expose the buffer layer.
One of the samples was placed in an oven set at 40° C. and left at 40±3° C. and 7% RH or less for 72 hours. Another sample was left under the conditions of 40±3° C. and 90±5% RH for 72 hours.
・ IR measurement and analysis Using an IRT-5200 device manufactured by JASCO Corporation, a PKM-GE-S (Germanium) crystal was attached, and the measurement was performed under the conditions of an incident angle of 45 °, room temperature, resolution of 4 cm ^-1 , and 100 integration times. .
When the infrared absorption spectrum was measured after the buffer layer was left under conditions of 40 ± 3 ° C. and 7% RH or less for 72 hours, the peak area between 2500 and 3700 cm ^-1 was the peak area between 1000 and 1600 cm ^-1 . Let A be the peak area ratio obtained by dividing,
When the infrared absorption spectrum was measured after the buffer layer was left for 72 hours under the conditions of 40 ± 3 ° C. and 90 ± 5% RH, the peak area between 2500 and 3700 cm ^-1 and the peak area between 1000 and 1600 cm ^-1 B/A was obtained, where B is the peak area ratio obtained by dividing by .
Regarding the calculation of the peak area, the area above the baseline was calculated using the analysis software attached to the device.

<Performance evaluation>
・Measurement of water vapor permeability Part 1 (sealed with calcium chloride)
8 g of calcium chloride was put into each of the prepared packaging bags, and the opening of the bag was heat-sealed to obtain a package. The initial mass (g) of the package was measured, and then left in an environment with a temperature of 40±2° C. and a humidity of 90±5% RH for 168 hours. Then, the mass (g) of the package was measured again to obtain the mass difference. This mass difference is divided by the inner surface area of the bag (0.01 m ² ) and the standing time ((168/24) days), and the water vapor permeability from the outer surface side to the inner surface side of the packaging bag (g/m ² · day) was obtained. This value is listed in Table 1.

・Measurement of water vapor permeability Part 2 (sealed sponge cake with a water activity of 0.9)
5 g of sponge cake having a water activity Aw of 0.9 was placed in each of the prepared packaging bags, and the opening of the bag was heat-sealed to obtain a package. The initial mass (g) of the package was measured, and then left in an environment with a temperature of 40±2° C. and a humidity of 7±3% RH for 168 hours. Then, the mass (g) of the package was measured again to obtain the absolute value of the mass difference. The absolute value of this mass difference is divided by the inner surface area of the bag (0.01 m ² ) and the standing time ((168/24) days), and the water vapor permeability from the inner surface side to the outer surface side of the packaging bag (g/ m ² ·day) was obtained. Table 1 shows the absolute values of the obtained numerical values.

From Table 1, it can be seen that the packaging bags (Examples 1 to 4) using a laminated film having specific four layers have significantly low water vapor permeation even after a high temperature and long-term evaluation at 40 ° C. for 168 hours. Recognize.
In particular, in Examples 1 to 4, permeation of water vapor was suppressed both when the content was calcium chloride and when the content was sponge cake. This indicates that the laminated film of the present embodiment (having four specific layers) can be preferably applied to both suppression of moisture absorption (anti-drinking) and suppression of dryness (moisture retention) of articles. In terms of numerical values, it is particularly preferable to apply the laminated film of the present embodiment to the suppression of moisture absorption (prevention of dryness) of articles.
On the other hand, from Comparative Example 1, when the B/A of the buffer layer exceeds 1.4 (high water absorption of the buffer layer), both performances of suppressing moisture absorption (preventing dryness) and suppressing dryness (moisture retention) are significantly worse. I know it will be. Moreover, from Comparative Example 2, it can be seen that when the buffer layer is not provided, the performance of drying suppression (moisture retention) is particularly poor.

1 laminated film 11 base film layer 12 inorganic layer (inorganic layer containing metal atoms)
13 buffer layer (buffer layer made of material other than polyvinylidene chloride resin)
14 polyvinylidene chloride layer (polyvinylidene chloride layer containing polyvinylidene chloride resin)
20 packaging body 21 packaging bag 22 article

Claims (6)

A substrate film layer, an inorganic layer containing metal atoms, a buffer layer made of a material other than polyvinylidene chloride resin, and a polyvinylidene chloride layer containing polyvinylidene chloride resin are laminated in this order,
When the infrared absorption spectrum was measured after the buffer layer was left under conditions of 40 ± 3 ° C. and 7% RH or less for 72 hours, the peak area between 2500 and 3700 cm ^-1 , the peak area between 1000 and 1600 cm ^-1 Let A be the peak area ratio obtained by dividing by
When the infrared absorption spectrum was measured after the buffer layer was left at 40 ± 3 ° C. and 90 ± 5% RH for 72 hours, the peak area between 2500 and ³⁷⁰⁰ cm ^-1 When the peak area ratio obtained by dividing by the area is B,
A laminated film having a B/A of 1.40 or less,
The buffer layer contains at least one thermoplastic resin selected from the group consisting of polyester resins, polyurethane resins, and ethylene-vinyl alcohol copolymers, or a cured UV-curable acrylic resin ,
The base film layer contains at least one selected from the group consisting of polyolefin, polyester, polyvinyl chloride, polyimide, ethylene-vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene and ionomer,
A laminated film containing only one inorganic layer. The laminated film according to claim 1 ,
The laminated film, wherein the inorganic layer containing metal atoms contains at least one selected from the group consisting of aluminum, aluminum oxide, silicon oxide, silicon oxynitride and silicon nitride. The laminated film according to claim 1 or 2 ,
A laminated film in which the base film layer contains a thermoplastic resin. A packaging material using the laminated film according to any one of claims 1 to 3 . A package in which an article is packaged using the packaging material according to claim 4 . A packaging bag made of the laminated film according to any one of claims 1 to 3 ,
Water vapor permeability from the outer surface side to the inner surface side of the packaging bag when calcium chloride is put in the packaging bag, sealed, and placed in an environment with a temperature of 40 ± 2 ° C and a humidity of 90 ± 5% RH for 168 hours. is 0.65 [g/m ² day] or less,
A food with a water activity of 0.90 is put in the packaging bag, sealed, and placed in an environment with a temperature of 40 ± 2 ° C and a humidity of 7 ± 3% RH for 168 hours, from the inner surface side to the outer surface of the packaging bag. A packaging bag having a water vapor permeability to the side of 1.0 [g/m ² ·day] or less.

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