JP7365131B2 - Manufacturing method of barrier film - Google Patents

Description

The present invention relates to a method for producing a barrier film, a barrier film, and a barrier package.

As a barrier film, a barrier film in which an inorganic layer and a polyvinylidene chloride resin layer are provided on the surface of a base film layer is known.
Techniques related to such barrier films include, for example, those described in Patent Document 1.

Patent Document 1 discloses that a vapor deposited film (B) of an inorganic material is formed on at least one side of a polymer film base material (A), and a coating film (B) of polyvinylidene chloride is further formed on the vapor deposited film (B). A composite vapor-deposited film characterized in that C) is laminated is described.
Patent Document 1 describes that such a composite vapor-deposited film has excellent gas barrier properties and bending fatigue resistance.

Japanese Patent Application Publication No. 08-39718

As mentioned above, a technique using vinylidene chloride as a barrier film has been proposed. However, for example, in the field of food packaging, there is a demand for longer expiration dates for the contents. Therefore, there is a need for further improvement in barrier properties against water vapor and oxygen.
The present invention has been made in view of these circumstances. The present invention aims to provide a method for producing a barrier film that can produce a barrier film that has especially excellent water vapor barrier properties.

According to the present invention, the following method for manufacturing a barrier film and the like are provided.

1.
A method for producing a barrier film comprising at least a base film layer and a polyvinylidene chloride resin layer, the method comprising:
A dissolving step of dissolving polyvinylidene chloride resin in an organic solvent to obtain a resin solution;
a precipitation step of aging the resin solution to obtain a precipitate-containing liquid in which at least a portion of the polyvinylidene chloride resin has precipitated;
a coating step of forming a polyvinylidene chloride resin layer by coating the precipitate-containing liquid on the base film and drying the organic solvent;
A method for producing a barrier film, comprising:
2.
1. A method for producing a barrier film according to
A method for producing a barrier film, wherein the precipitate-containing liquid has an absorbance of 0.5 or more at a wavelength of 660 nm, as measured using a spectrophotometer with an optical path length of 1 cm.
3.
1. or 2. A method for producing a barrier film according to
In the dissolving step, (i) the polyvinylidene chloride resin is dissolved in an organic solvent consisting of a mixture of a good solvent and a poor solvent, or (ii) the polyvinylidene chloride resin is dissolved in a good solvent. A method for producing a barrier film, in which a poor solvent is added after that.
4.
1. ~3. A method for producing a barrier film according to any one of
The base film includes an inorganic layer containing one or more selected from the group consisting of silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, and aluminum,
In the coating step, the precipitate-containing liquid is coated on the inorganic layer.
5.
1. ~4. A method for producing a barrier film according to any one of
A method for producing a barrier film, wherein a polyurethane adhesive layer is formed between the base film layer and the polyvinylidene chloride resin layer.
6.
1. ~5. A method for producing a barrier film according to any one of
The polyvinylidene chloride resin layer contains one or more selected from the group consisting of isocyanate compounds, silane coupling agents, urethane resins, urea resins, melamine resins, epoxy resins, and alkyd resins. A method for producing a barrier film containing an adhesive component.
7.
1. ~6. A barrier film obtained by the method for producing a barrier film according to any one of the above.
8.
7. A barrier packaging body comprising a barrier film.

By producing a barrier film using the production method of the present invention, a barrier film with excellent water vapor barrier properties is provided.

1 is a cross-sectional view schematically showing an example of the structure of a barrier film. 2 is a cross-sectional view schematically showing an example of the structure of a barrier film different from that in FIG. 1. FIG. It is a diagram for supplementing the outline of an absorption spectrum obtained by measuring infrared absorption of a barrier film and how to read it. It is a graph showing the relationship between the absorbance (wavelength 660 nm) of the coating liquid and the water vapor permeability in Examples and Comparative Examples.

Embodiments of the present invention will be described below with reference to the drawings.
In all the drawings, similar components are denoted by the same reference numerals, and description thereof will be omitted as appropriate. Moreover, the drawings are only schematic diagrams. The dimensional ratios in the drawings do not necessarily match the actual dimensional ratios.
Unless otherwise specified, "~" between numbers in a sentence represents the following from the above. For example, "1 to 5% by mass" means "1 to 5% by mass".

<Production method of barrier film, barrier film, barrier package>
FIG. 1 is a cross-sectional view schematically showing an example of the structure of a barrier film 100 manufactured by the method for manufacturing a barrier film of this embodiment.
The barrier film 100 includes a base film layer 103 and a polyvinylidene chloride resin layer 101 on at least one side thereof.

In this embodiment, the barrier film 100 can be manufactured through at least the following three steps (1) to (3).
(1) A dissolving step in which polyvinylidene chloride resin is dissolved in an organic solvent to form a resin solution.
(2) A precipitation step of aging the resin solution of (1) above to obtain a precipitate-containing liquid in which at least a portion of the polyvinylidene chloride resin has precipitated.
(3) A coating step of forming the polyvinylidene chloride resin layer 101 by coating the precipitate-containing liquid of (2) above on at least one side of the base film layer 103 and drying the organic solvent.

When forming a resin film by a coating method, it is generally considered preferable that the coating solution be a "uniform solution" from the viewpoint of uniform and smooth coating.
However, the present inventor intentionally used a coating solution in which at least a portion of the polyvinylidene chloride resin was precipitated in an organic solvent when coating a coating solution containing a polyvinylidene chloride resin, thereby creating a barrier film. It has been found that the performance of 100 can be improved.

Although some aspects of the mechanism of performance improvement are unclear, it is presumed that the precipitated resin forms plate-shaped lamellae, and when applied onto the base film, the resin becomes plate-shaped crystals. It is assumed that these plate-like crystals increase the crystallinity of the entire barrier film and are arranged parallel to the surface of the base film, creating a so-called "maze effect" in the gas permeation mechanism, improving barrier performance. .

Hereinafter, the method for manufacturing the barrier film of this embodiment will be explained in more detail.

(melting process)
In the dissolution step, polyvinylidene chloride resin is dissolved in an organic solvent to form a resin solution. The melting temperature depends on the resin composition, but for example, the polyvinylidene chloride resin is dissolved (preferably completely dissolved) in an organic solvent under conditions of 40°C or higher, preferably 40 to 60°C, more preferably 45 to 55°C. ).

In the dissolution step, the amount of polyvinylidene chloride resin and other components (for example, adhesive components described below) to be used in the organic solvent is not particularly limited as long as the polyvinylidene chloride resin is precipitated in the precipitation step described below. From the viewpoint of obtaining a sufficient amount of precipitation in the precipitation process, ease of application in the coating process, and forming a polyvinylidene chloride resin layer with an appropriate thickness, the nonvolatile component concentration of the resin solution is, for example, 1 to 15% by mass. %, preferably 3 to 12% by weight.

The organic solvent for dissolving the polyvinylidene chloride resin may be appropriately selected depending on the type of polyvinylidene chloride resin used, and is not particularly limited.
For example, ketones such as acetone, methyl ethyl ketone (also referred to as MEK), and cyclohexanone; ethers such as dioxane, diethyl ether, and tetrahydrofuran (also referred to as THF); aromatic hydrocarbons such as benzene, toluene, and xylene; ethyl acetate, acetic acid Examples include esters such as butyl; amides such as dimethylformamide; mixed solvents thereof; and the like.

In the dissolution step, (i) the polyvinylidene chloride resin is dissolved in an organic solvent consisting of a mixture of a good solvent and a poor solvent, or (ii) after the polyvinylidene chloride resin is dissolved in a good solvent, Preferably, a poor solvent is added. By doing so, the time until precipitation can be appropriately shortened, and the crystalline state of the precipitates can be controlled to further enhance barrier properties.
In this embodiment, a good solvent is one that can dissolve 5 g or more of polyvinylidene chloride resin per 100 g of solvent at 50°C. In addition, a poor solvent refers to a solvent that is not a good solvent, that is, one that can dissolve less than 5 g of polyvinylidene chloride resin per 100 g of solvent at 50°C.

The organic solvent consisting of the mixture of (i) above preferably contains a mixture of at least two selected from aromatic solvents, ketone solvents, and ether solvents, and among them, a mixed solvent of tetrahydrofuran and toluene, a mixed solvent of methyl ethyl ketone, A mixed solvent with toluene or a mixed solvent with tetrahydrofuran, toluene, and methyl ethyl ketone is preferred. In particular, it is preferable to use tetrahydrofuran as a good solvent.

In the above embodiment (ii) in which a poor solvent is added after dissolving with a good solvent, it is preferable to use, for example, tetrahydrofuran as the good solvent, and toluene, MEK, or ethyl acetate as the poor solvent.

The polyvinylidene chloride resin to be dissolved in the organic solvent is not particularly limited as long as it contains a structural unit derived from a vinylidene chloride monomer as a structural unit. Polyvinylidene chloride (PVDC) containing 100% by mass of vinylidene chloride may be used. Alternatively, it may be a copolymer of vinylidene chloride and a monomer copolymerizable with vinylidene chloride.

The copolymer has a content of vinylidene chloride of 60% by mass or more and less than 100% by mass, and a content of a monomer copolymerizable with vinylidene chloride of more than 0% by mass and 40% by mass or less. Copolymers can be exemplified.
Examples of monomers copolymerizable with vinylidene chloride include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and (meth)acrylate. Isobutyl acid, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, cyclohexyl (meth)acrylate, n-octyl (meth)acrylate, (meth)acrylate C1-18 alkyl ester or cycloalkyl ester of (meth)acrylic acid such as lauryl acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, methoxybutyl (meth)acrylate, (meth)acrylic acid (Meth)acrylic acid esters such as alkoxyalkyl esters having 2 to 18 carbon atoms of (meth)acrylic acid such as methoxyethyl acid and ethoxybutyl (meth)acrylate; (meth)acrylic acid, crotonic acid, itaconic acid, Ethylenically based α,β-unsaturated carboxylic acids and salts thereof having a carboxyl group such as itaconic anhydride, maleic acid, maleic anhydride, fumaric acid, citraconic acid; unsaturated amide compounds such as (meth)acrylamide, diacetone acrylamide, etc. ; Nitrile group-containing monomers such as acrylonitrile and methacrylonitrile; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and ) Hydroxyalkyl esters having 2 to 8 carbon atoms of acrylic acid or (meth)acrylic acid such as hydroxybutyl acrylate; polyoxyethylene monoacrylate, polyoxyethylene monomethacrylate, N-methylol (meth)acrylamide, allyl alcohol, etc. Hydroxyl group-containing monomer; selected from other polymerizable unsaturated monomers such as styrene, α-methylstyrene, vinyl chloride, butadiene, vinyltoluene, vinyl acetate, itaconic acid alkyl ester, ethylene, propylene, isobutylene, etc. One or more types can be mentioned.

As the polyvinylidene chloride resin, commercially available products may be used. As a commercially available product, Saran (trademark) resin series manufactured by Asahi Kasei Co., Ltd., etc. can be preferably used.

The proportion of polyvinylidene chloride resin in the nonvolatile components (components other than the organic solvent) of the resin solution is usually 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably It is 80% by weight or more, particularly preferably 90% by weight or more, particularly preferably 100% by weight. By increasing the proportion of polyvinylidene chloride resin in the nonvolatile components of the resin solution, it is possible to increase the proportion of polyvinylidene chloride resin in the film obtained by coating. Thereby, the performance balance of blocking resistance and barrier properties can be improved.

In addition to the polyvinylidene chloride resin, the resin solution may contain additional components for various purposes.
For example, the resin solution may further contain an adhesive component from the viewpoint of improving the adhesiveness between the polyvinylidene chloride resin layer and other layers. By using a resin solution obtained by dissolving the adhesive component together with the polyvinylidene chloride resin in an organic solvent, a polyvinylidene chloride resin layer containing the adhesive component can be provided.

Examples of the adhesive component include one or more selected from the group consisting of isocyanate compounds; silane coupling agents; adhesive resins such as urethane resins, urea resins, melamine resins, epoxy resins, and alkyd resins; Two or more types can be preferably mentioned.

Examples of the isocyanate compound include polyvalent isocyanates, which are included as components for forming the adhesive layer described below. Commercially available products may be used as the isocyanate compound. Commercially available products include Mitsui Chemicals' "Takenate" series.

Examples of the silane coupling agent include halogen-containing silane coupling agents such as 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-chloropropyltrimethoxysilane, and 3-chloropropyltriethoxysilane; 2 -(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, 2-glycidyloxyethyltri Epoxy group-containing silane coupling agents such as methoxysilane, 2-glycidyloxyethyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane; 2-aminoethyltrimethoxysilane, 3-amino Propyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-[N-(2-aminoethyl)amino]ethyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, 3 -(2-aminoethyl)aminopropyltriethoxysilane, 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane and other amino group-containing silane coupling agents; 2-mercaptoethyltrimethoxysilane, 3- Mercapto group-containing silane coupling agents such as mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane; 2-methacryloyloxyethyltrimethoxysilane , 2-methacryloyloxyethyltriethoxysilane, 2-acryloyloxyethyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, etc. (meth) Examples include acryloyl group-containing silane coupling agents.
When using a silane coupling agent, one type may be used alone, or two or more types may be used in combination.

(Precipitation process)
In the precipitation step, the resin solution prepared in the dissolution step is allowed to age to form a precipitate-containing liquid in which at least a portion of the polyvinylidene chloride resin has precipitated.
For example, in the dissolution process, a resin solution that has been heated to completely dissolve polyvinylidene chloride resin can be stored (specifically, left standing) at a temperature below the complete dissolution temperature to prevent precipitates from forming. It can be made into a liquid.
The temperature during storage can be, for example, around room temperature (20 to 30°C, preferably 20 to 25°C).
The storage time can be generally 24 to 336 hours (14 days), preferably 72 to 168 hours (7 days).

The precipitate-containing liquid is usually cloudy. If the degree of cloudiness is appropriate, the barrier properties of the produced barrier film can be further improved.
The degree of cloudiness can be quantified, for example, by absorbance. Specifically, the absorbance of the precipitate-containing liquid at a wavelength of 660 nm, measured using a spectrophotometer with an optical path length of 1 cm, is typically 0.2 or more, preferably 0.3 or more, and more preferably 0. .5 or more, more preferably 1.0 or more, particularly preferably 3.0 or more (the wavelength "660 nm" is selected from the viewpoint that absorption by organic solvents such as THF, toluene, and MEK is small). A moderately high absorbance is considered to correspond to sufficient crystallization of the resin in the precipitate-containing liquid, and is therefore preferable.
Further, the absorbance is preferably 5.0 or less, more preferably 4.0 or less.

The total solids concentration (nonvolatile component concentration) of the precipitate-containing liquid is, for example, 1 to 15% by mass, preferably 5 to 15% by mass, and more preferably 5 to 10% by mass, from the viewpoint of ease of application. Note that the "total solids concentration" here refers to the combined concentration of both "precipitates" and "components that remain dissolved without being precipitated" in the precipitate-containing liquid.

(Coating process)
In the coating step, the precipitate-containing liquid obtained in the precipitation step is applied onto the base film and the organic solvent is dried to form a polyvinylidene chloride resin layer.

The base film (base film layer 103) preferably contains a thermoplastic resin, and is more preferably formed of a sheet-like or film-like base material made of a thermoplastic resin. As the thermoplastic resin, a known thermoplastic resin can be used. For example, polyolefins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; Examples include one or more selected from polyamides such as meta-xylene adipamide; polyvinyl chloride; polyimide; ethylene/vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomer; and the like.
Among these, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polyamide are preferred from the viewpoint of good stretchability and transparency.

The base film formed of a thermoplastic resin may be a non-stretched film or a stretched film.
An inorganic layer described below or other layers may be provided on one or both sides of the base film. Further, in order to improve the adhesiveness with the polyvinylidene chloride resin layer, surface activation treatment such as corona treatment, flame treatment, plasma treatment, primer coating treatment, etc. may be performed.
The thickness of the base film is usually 1 to 200 μm, preferably 5 to 150 μm.

The specific method of coating is not particularly limited, and any known method can be applied. For example, a coating method using a known coating machine such as an air knife coater, a kiss roll coater, a metering bar coater, a gravure roll coater, a reverse roll coater, a dip coater, or a die coater can be mentioned.

The specific method of drying after coating is not particularly limited, and any known method can be applied. For example, a method of drying 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 mentioned.
The drying temperature varies depending on the heat resistance of the base film, but is usually 50 to 200°C, preferably 70 to 150°C, and more preferably 100 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.

The coating amount of the precipitate-containing liquid and the thickness of the polyvinylidene chloride resin layer 101 are not particularly limited, and may be adjusted as appropriate based on desired barrier properties and the like. From the viewpoint of the balance of barrier properties, transparency, handleability, etc., the final thickness of the polyvinylidene chloride resin layer 101 (after drying) is preferably 0.05 to 20 μm, more preferably 0.1 to 20 μm. The thickness is 15 μm, more preferably 0.3 to 10 μm, particularly preferably 0.5 to 5 μm, particularly preferably 0.5 to 3 μm.

(Aging treatment)
After the coating step, an aging treatment may be further performed. It is thought that the aging treatment improves the degree of crystallinity of the polyvinylidene chloride resin after application, further enhancing the barrier performance.
For example, it is possible to perform aging treatment by leaving the dried film obtained in the coating step at room temperature, but preferably the aging treatment is performed in an oven or the like.
From the viewpoint of shortening the processing time and preventing damage to the film due to heating, the temperature of the aging treatment may be set in consideration of the heat resistance and melting point of the film base material. For example, in the case of stretched polypropylene, the temperature is preferably 30 to 80°C, more preferably 35 to 60°C, and still more preferably 35 to 50°C.
The aging treatment time varies depending on temperature conditions, but is preferably 6 to 168 hours, more preferably 12 to 120 hours, even more preferably 24 to 96 hours, and particularly preferably 48 to 72 hours.

(Variation of layer structure)
Up to this point, the method for producing a barrier film with a "two-layer structure" has been mainly described, in which the polyvinylidene chloride resin layer 101 is provided on at least one side of the base film layer 103 by applying a precipitate-containing liquid. On the other hand, in this embodiment, the barrier film may include layers other than the polyvinylidene chloride resin layer 101 and the base film layer 103.

- Embodiment with an inorganic layer FIG. 2 is a diagram schematically showing an embodiment in which an inorganic layer 105 is further laminated between the polyvinylidene chloride resin layer 101 and the base film layer 103 in the barrier film 100. It is.
The inorganic layer 105 can further improve barrier performance such as oxygen barrier property and water vapor barrier property while maintaining good blocking resistance.

Examples of the inorganic material constituting the inorganic material layer 105 include metals, metal oxides, and the like that can form a thin film having barrier properties. Specifically, periodic table group 2A elements such as beryllium, magnesium, calcium, strontium, and barium; periodic table transition elements such as titanium, zirconium, ruthenium, hafnium, and tantalum; periodic table group 2B elements such as zinc; aluminum, and gallium. , indium, thallium, etc.; Periodic Table 4A group elements such as silicon, germanium, tin, etc.; Periodic Table 6A group elements such as selenium, tellurium, etc. One or two selected from simple substances or oxides, etc. The above can be mentioned (in the above, group names in the periodic table are shown in the old CAS format).

Among the above-mentioned inorganic substances, one or more inorganic substances selected from the group consisting of silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, and aluminum are preferred because they have an excellent balance of barrier properties, cost, etc. .
Silicon oxide may contain silicon monoxide and silicon suboxide in addition to silicon dioxide.

The inorganic layer 105 may be composed of a single inorganic layer, or may be composed of a plurality of inorganic layers. Furthermore, when the inorganic layer 105 is composed of a plurality of inorganic layers, it may be composed of the same type of inorganic layer or different types of inorganic layers.

The thickness of the inorganic layer 105 is preferably 1 to 500 nm, more preferably 2 to 300 nm, and even more preferably 5 to 150 nm, from the viewpoint of balance among barrier properties, adhesion, handling properties, and the like. The thickness of the inorganic layer 105 can be determined from an image observed using a transmission electron microscope or a scanning electron microscope.

The method for forming the inorganic layer 105 is not particularly limited. For example, the inorganic layer 105 can be formed on one or both sides of the base film layer 103 by a vacuum process such as a vacuum evaporation method, a sputtering method, or a plasma vapor deposition method (CVD method), a sol-gel process, or the like.
A barrier film is manufactured by applying a precipitate-containing liquid to the surface of the inorganic layer 105 of the base film layer 103 provided with the inorganic layer 105 as described above (coating step). be able to.

・A mode including two or more barrier resin layers (polyvinylidene chloride resin-containing layer) In the mode as explained in FIG. 1 or the mode as provided with an inorganic layer as explained in FIG. 2, additional A barrier resin layer (specifically, an additional polyvinylidene chloride resin-containing layer) may be provided. That is, the barrier film may have a four-layer structure in which a base layer, an inorganic layer, a polyvinylidene chloride resin-containing layer, and an additional polyvinylidene chloride resin-containing layer are laminated in this order.

The additional polyvinylidene chloride resin-containing layer is preferably a layer formed of latex containing fine particles of polyvinylidene chloride resin. This layer can be provided, for example, by applying latex containing fine particles of polyvinylidene chloride resin and drying it.

- Embodiment with an adhesive layer For the purpose of improving interlayer peel strength, an adhesive layer may be provided between the base film layer and the polyvinylidene chloride resin-containing layer.

The adhesive layer is preferably a polyurethane adhesive layer. The polyurethane adhesive layer is preferably formed from, for example, a polyester polyol and a curing agent such as a polyvalent isocyanate.
A polyester polyol is a polyester obtained by the reaction of a polycarboxylic acid and a polyol. The polyol used as a raw material is a compound having at least two or more hydroxyl groups in the molecule, and includes, for example, a low molecular weight polyol and a high molecular weight polyol.

Examples of low molecular weight polyols include ethylene glycol, propanediol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,6-hexanediol, neopentyl glycol, alkanes (C7- C22) Diol, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexanedimethanol, alkane-1,2-diol (C17-C20), bisphenol A, hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, 2 , 6-dimethyl-1-octene-3,8-diol, bishydroxyethoxybenzene, xylene glycol, bishydroxyethylene terephthalate, and other low molecular weight diols; glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol , 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, 1,1,1-tris(hydroxymethyl)propane, 2,2-bis(hydroxymethyl)-3-butanol, and Examples include low molecular weight triols such as other aliphatic triols (C8 to C24); low molecular weight polyols having four or more hydroxyl groups such as tetramethylolmethane, D-sorbitol, xylitol, D-mannitol, and D-mannitol.

Examples of high molecular weight polyols include polyether polyols, polyester polyols, polycarbonate polyols, acrylic polyols, epoxy polyols, natural oil polyols, silicone polyols, fluorine polyols, polyolefin polyols, and the like.

Examples of the polyester polyol include one or more of the above-mentioned low molecular weight polyols, or one or more of the high molecular weight polyols, such as oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, Adipic acid, 1,1-dimethyl-1,3-dicarboxypropane, 3-methyl-3-ethylglutaric acid, azelaic acid, sebacic acid, other aliphatic dicarboxylic acids (C11 to C13), hydrogenated dimer acid , maleic acid, fumaric acid, itaconic acid, orthophthalic acid, isophthalic acid, terephthalic acid, toluene dicarboxylic acid, dimer acid, het acid, and other carboxylic acids, and acid anhydrides derived from these carboxylic acids; acids, succinic anhydride, maleic anhydride, phthalic anhydride, 2-alkyl (C12-C18) succinic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, and acid halides derived from these carboxylic acids, etc. Examples include polyester polyols obtained by reaction with oxalic acid dichloride, adipic acid dichloride, sebacic acid dichloride, and the like.

The polyvalent isocyanate which is a curing agent for forming the polyurethane adhesive layer is preferably a compound having at least two or more isocyanate groups in the molecule. Specific examples include aromatic polyisocyanates, araliphatic polyisocyanates, alicyclic polyisocyanates, aliphatic polyisocyanates, and the like.

Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 2,4- or Aromatic diisocyanates such as 2,6-tolylene diisocyanate (TDI) or mixtures thereof, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate; triphenylmethane-4,4',4''-triisocyanate , 1,3,5-triisocyanate benzene, 2,4,6-triisocyanate toluene and other aromatic triisocyanates; 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate and other aromatic triisocyanates. Examples include tetraisocyanate.

Examples of the araliphatic polyisocyanate include 1,3- or 1,4-xylylene diisocyanate (XDI) or a mixture thereof, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4 Examples include aromatic aliphatic diisocyanates such as -bis(1-isocyanate-1-methylethyl)benzene (TMXDI) or mixtures thereof; and aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatemethylbenzene.

Examples of the alicyclic polyisocyanate include 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), 4,4'-methylenebis(cyclohexyl isocyanate) (H12MDI), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI) Alicyclic diisocyanates such as or mixtures thereof; 1,3,5-triisocyanatecyclohexane, 1,3,5-trimethylisocyanatecyclohexane, 2-(3-isocyanatepropyl)-2,5-di(isocyanatemethyl)-bicyclo (2.2.1) Heptane, 2-(3-isocyanatepropyl)-2,6-di(isocyanatemethyl)-bicyclo(2.2.1)heptane, 3-(3-isocyanatepropyl)-2,5 -di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanateethyl)-2-isocyanatemethyl-3-(3-isocyanatepropyl)-bicyclo(2.2.1)heptane, 6-(2-Isocyanatoethyl)-2-Isocyanatomethyl-3-(3-Isocyanatopropyl)-bicyclo(2.2.1)heptane, 5-(2-Isocyanatoethyl)-2-Isocyanatemethyl-2-( 3-Isocyanatepropyl)-bicyclo(2.2.1)-heptane, 6-(2-isocyanateethyl)-2-isocyanatemethyl-2-(3-isocyanatepropyl)-bicyclo(2.2.1)heptane, etc. Examples include alicyclic triisocyanates.

Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1 , 3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, aliphatic diisocyanates such as 2,6-diisocyanate methyl caproate; lysine ester triisocyanate, 1,4,8- Triisocyanate octane, 1,6,11-triisocyanate undecane, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-triisocyanate hexane, 2,5,7-trimethyl-1,8-diisocyanate- Examples include aliphatic triisocyanates such as 5-isocyanate methyloctane.

These polyisocyanates may be used alone or in combination of two or more. Preferred are aromatic, araliphatic, alicyclic and aliphatic diisocyanates.

A commercially available product may be used as the adhesive forming the adhesive layer. For example, a mixture of the "Takelac" series and the "Takenate" series manufactured by Mitsui Chemicals, Inc. can be used.

- Embodiment with a heat sealing layer In order to impart heat sealability, a heat sealing layer may be provided on at least one side of the barrier film.
Basically, the heat sealing layer can be provided by appropriately applying a known material. For example, homopolymers or copolymers of α-olefins such as ethylene, propylene, butene-1, hexene-1, 4-methyl-pentene-1, octene-1, high-pressure low density polyethylene, linear low density polyethylene (so-called LLDPE), high-density polyethylene, polypropylene, polypropylene random copolymer, low-crystalline or amorphous ethylene/propylene random copolymer, ethylene/butene-1 random copolymer, propylene/butene-1 random copolymer A layer formed from a resin composition containing one or more polyolefins selected from polymers, a layer formed from a resin composition containing ethylene/vinyl acetate copolymer (EVA), and a layer formed from a resin composition containing EVA and polyolefin. Examples include a layer formed from a resin composition containing.

-Other layers The barrier film may be provided with various coating layers and laminate layers, such as a slippery layer and an antistatic layer.

(Applications, barrier performance)
The barrier film of this embodiment (barrier film obtained by a specific manufacturing method) can be used, for example, as a packaging film that requires barrier performance. Specifically, it is suitable as a packaging film for packaging foods, medicines, daily miscellaneous goods, etc.; a film for vacuum insulation panels; a sealing film for sealing electroluminescent elements, solar cells, etc. can be used.
Moreover, the barrier film of this embodiment can also be suitably used as a barrier film constituting a barrier package. The barrier packaging body is, for example, a barrier packaging bag itself made of the barrier film of this embodiment that is used for the purpose of filling contents, or a packaging bag filled with contents. be. Further, depending on the use, a barrier film may be used for a part of the barrier packaging bag, or a barrier film may be used for the entire barrier packaging bag.

The barrier film of this embodiment has excellent water vapor barrier properties. Specifically, the water vapor permeability of the barrier film 100 measured at a temperature of 40° C. and a humidity of 90% RH is preferably 10 g/m ² ·day or less, more preferably 5 g/m ² ·day or less , particularly preferably 3 g/m ² ·day or less. Water vapor permeability is determined by making a barrier film into a bag, putting calcium chloride in it, heat sealing it, and storing it in an environment with a temperature of 40°C and a humidity of 90% RH, as described in the examples below. (calculated from the change in mass before and after storage and the inner surface area of the bag).
The water vapor permeability can be appropriately adjusted by adjusting the thickness of the polyvinylidene chloride resin layer, adding an inorganic layer and adjusting the thickness, controlling the crystallinity of the polyvinylidene chloride resin layer, and the like.

The barrier film of this embodiment preferably has excellent oxygen barrier properties. Specifically, in accordance with JIS K 7126-2:2006, the oxygen permeability measured at a temperature of 20°C and a humidity of 90% RH is preferably 2.0 ml/ ^m2・day・MPa or less. Preferably it is 1.5 ml/m ² ·day · MPa or less, more preferably 1.0 ml/m ² ·day · MPa or less, particularly preferably 0.5 ml/m ² ·day · MPa or less.

(About crystallinity of polyvinylidene chloride resin in barrier film)
As described above, in this embodiment, by applying the precipitate-containing liquid in which at least a portion of the polyvinylidene chloride resin has precipitated, it is considered that a portion of the polyvinylidene chloride resin is in a crystalline state.

According to various findings, infrared spectroscopy (IR) is useful for investigating this "crystalline state." In particular, it is useful to measure the surface of the polyvinylidene chloride resin layer 101 by an Attenuated Total Reflection method (ATR method) and analyze its spectrum.

Specifically ^, the absorption peak height (maximum value) is A(1070), and the absorption peak height (maximum value) at a wave number near 1046 cm ^-1 is A(1046), then the peak ratio ( (also simply referred to as “peak ratio”) is an index of the degree of crystallinity of the polyvinylidene chloride resin layer 101.

In the infrared spectrum, A(1070) is a value indicating an amorphous region, and the larger the amorphous region, the larger the value. On the other hand, A(1046) is a value indicating a crystal region, and the larger the crystal region, the larger the value. Therefore, the larger the peak ratio, the higher the crystallinity, and the smaller the peak ratio, the lower the crystallinity.

This peak ratio is preferably 2.10 or more. A peak ratio of 2.10 or more corresponds to a sufficiently high degree of crystallinity of the polyvinylidene chloride resin. This allows the barrier film 100 to have good water vapor barrier properties. The peak ratio is more preferably 2.20 or more, still more preferably 2.30 or more. The upper limit of the peak ratio is not particularly limited, but is preferably 8.0 or less, or 6.0 or less, for example.

The peak ratio can be determined, for example, by cutting out a 1 cm x 3 cm measurement sample from the barrier film 100 and obtaining an infrared absorption spectrum of its surface (polyvinylidene chloride resin layer 101) using the ATR method.
Infrared spectrum measurement (ATR method) is carried out using, for example, an FT-IR350 device manufactured by JASCO Corporation, equipped with a KRS-5 (Thallium Bromide-Iodide) crystal, at an incident angle of 45°, at room temperature, with a resolution of 4 cm ^-1 , and an integration. It can be performed under the conditions of 150 times.

In the absorption spectrum, the minimum point of absorbance near 1060 cm ⁻¹ and the point of absorbance at 1010 cm ⁻¹ are connected with a straight line. This straight line is defined as the baseline _L1 for determining the value of A(1046). Then, draw a straight line directly below from the maximum absorption point at a wave number near 1046 cm ^-1 , and let A be the length until it intersects with the baseline.
Further, in the absorption spectrum, the minimum point of absorbance near 1080 cm ⁻¹ and the minimum point of absorbance near 1060 cm ⁻¹ are connected by a straight line. This straight line is defined as the baseline _L2 for determining the value of A(1070). Then, draw a straight line directly below from the maximum point of absorption at a wave number near 1070 cm ^-1 , and let the length to intersect with the baseline be B.
Then, the value of A/B can be taken as the peak ratio.

For reference, Figure 3 shows the outline of the infrared spectrum chart obtained by measuring the barrier film of this embodiment using the ATR method, and supplements on how to read it (how to draw the baseline, lengths of A and B). are doing.

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above may also be adopted.

Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. The invention is not limited to the examples.

<Measurement/evaluation method>
First, measurement and evaluation methods in Examples and Comparative Examples will be explained.

(Measurement of absorbance of coating liquid)
Using a spectrophotometer "V-670" manufactured by JASCO Corporation, fixed wavelength measurement (wavelength 660 nm, photometry mode Abs, response Medium) was performed after auto-zero. A two-sided glass transparent cell manufactured by SANSYO (optical path length 10 mm x width 10 mm x height 45 mm, plate thickness 1.25 mm) was used as the cell.

(Measurement of peak ratio (A(1046)/A(1070)))
Cut out a 1 cm x 3 cm measurement sample from the barrier film obtained in the Examples and Comparative Examples, and obtain the infrared absorption spectrum of its surface (polyvinylidene chloride resin layer) by infrared total reflection measurement (ATR method). The peak ratio (A(1046)/A(1070)) was determined.
The infrared spectrum was measured (infrared total reflection measurement: ATR method) using an FT-IR350 device manufactured by JASCO Corporation, equipped with a KRS-5 (Thallium Bromide-Iodide) crystal, at an incident angle of 45 degrees, at room temperature, and with a resolution of 4 cm ^-1. The test was carried out under the condition that the number of integrations was 150.

(Measurement of water vapor permeability)
The produced film was made into a bag with the polyvinylidene chloride resin layer side facing the inner surface so that the inner surface area was 0.01 m ² . 10 g of calcium chloride was placed in the resulting bag, and the entrance of the bag was heat-sealed.
Next, the obtained bag was stored for 72 hours (3 days) in an environment with a temperature of 40° C. and a humidity of 90% RH.
The water vapor permeability was calculated from the difference in mass before and after storage (that is, the amount of moisture absorbed), the inner surface area of the bag, and the time (unit: g/(m ² ·d)).

<Preparation of resin solution>
(Preparation of liquid A)
Polyvinylidene chloride resin (Saran (trademark) Resin R204) manufactured by Asahi Kasei Corporation was dissolved in tetrahydrofuran heated to 50°C. Then toluene was added. Thereby, a 5% by mass polyvinylidene chloride solution was prepared using tetrahydrofuran:toluene=1:2 (mass ratio) as a solvent. This solution will be referred to as Solution A.

(Preparation of liquid B)
Polyvinylidene chloride resin (Saran (trademark) Resin R204) manufactured by Asahi Kasei Corporation was dissolved in tetrahydrofuran heated to 50°C. Then toluene was added. As a result, a 5% by mass polyvinylidene chloride solution was prepared using tetrahydrofuran:toluene=2:1 (mass ratio) as a solvent. This solution will be referred to as Solution B.

<Resin precipitation and coating>
In all Examples and Comparative Examples, the absorbance of the coating liquid was measured immediately before the coating liquid was applied.
Moreover, when using a mixture of A liquid and B liquid, after each liquid was produced, they were mixed immediately and left at room temperature.

[Example 1]
As a base film, biaxially oriented polyethylene terephthalate (manufactured by Unitika, trade name: Enplet PET #12) with a thickness of 12 μm was prepared.
Solution A, which was prepared as a coating solution and left at room temperature for 168 hours to precipitate at least a portion of the polyvinylidene chloride resin, was applied to the corona-treated surface of this using a Mayer bar. Thereafter, it was dried at 100° C. for 30 seconds using a hot air dryer. Thereby, a polyvinylidene chloride laminate film having a coating amount of 1.2 g/m ² (solid content) was obtained. Thereafter, it was aged in an oven at 40°C for 3 days.
The IR peak ratio and water vapor permeability of the sample obtained as described above were measured.

[Example 2]
As the coating liquid, a liquid was used in which liquid A and liquid B were mixed (liquid A: liquid B = 75:25 (mass ratio)) and left at room temperature for 168 hours to precipitate at least a portion of the polyvinylidene chloride resin. A sample was prepared in the same manner as in Example 1 except for the following. Then, the IR peak ratio and water vapor permeability were measured.

[Example 3]
Except that a coating liquid was used in which liquid A and liquid B were mixed (liquid A: liquid B = 50:50 (mass ratio)) and left at room temperature for 168 hours to precipitate at least a portion of the polyvinylidene chloride resin. A sample was prepared in the same manner as in Example 1. Then, the IR peak ratio and water vapor permeability were measured.

[Example 4]
A sample was produced in the same manner as in Example 1, except that Solution A was used as a coating solution that was left at room temperature for 24 hours after production to precipitate at least a portion of the polyvinylidene chloride resin. Then, the IR peak ratio and water vapor permeability were measured.

[Comparative example 1]
A sample was produced in the same manner as in Example 1, except that 100% B solution, which was left at room temperature for 168 hours after production, was used as the coating solution. Then, the IR peak ratio and water vapor permeability were measured.

[Comparative example 2]
A sample was prepared in the same manner as in Example 1, except that 100% of liquid A immediately after preparation was used as the coating liquid. Then, the IR peak ratio and water vapor permeability were measured.

[Comparative example 3]
A sample was prepared in the same manner as in Example 1, except that the liquid immediately after mixing the A liquid and the B liquid (A liquid: B liquid = 75:25 (mass ratio)) was used as the coating liquid. Then, the IR peak ratio and water vapor permeability were measured.

[Comparative example 4]
A sample was prepared in the same manner as in Example 1, except that the liquid immediately after mixing A liquid and B liquid (A liquid: B liquid = 50:50 (mass ratio)) was used. Then, the IR peak ratio and water vapor permeability were measured.

[Comparative example 5]
A sample was prepared in the same manner as in Example 1, except that a mixture of liquid A and liquid B (liquid A: liquid B = 50:50 (mass ratio)) and a liquid that was left to stand for 24 hours was used. Then, the IR peak ratio and water vapor permeability were measured.

The results of each example and comparative example are summarized in Table 1. For reference, FIG. 4 shows a plot of the relationship between the absorbance (wavelength: 660 nm) of the coating liquid and the water vapor permeability in all Examples and Comparative Examples.

The water vapor permeability of the barrier films of Examples 1 to 4 was 6.5 g/m ² ·day or less, indicating excellent water vapor barrier properties. On the other hand, in Comparative Examples 1 to 5, the water vapor permeability was higher than that in Examples 1 to 4, and the barrier properties were clearly inferior.
From the comparison between Examples and Comparative Examples, it is understood that forming a polyvinylidene chloride resin layer by applying a coating liquid in which at least a portion of polyvinylidene chloride resin has precipitated is important for improving water vapor barrier properties. be done.

In addition, from FIG. 4, by forming a polyvinylidene chloride resin layer using a coating liquid with sufficiently large absorbance (wavelength 660 nm) (that is, a coating liquid in which polyvinylidene chloride resin has precipitated), water vapor It can be seen that a barrier film with good barrier properties was obtained.

Further, when the IR peak ratio was 2.1 or more, the water vapor permeability was low, and when the IR peak ratio was less than 2.1, the water vapor permeability was high. It can be seen that the IR peak ratio is related to the crystallinity (and thus the water vapor barrier property) of the polyvinylidene chloride resin layer.

[Example 5]
Example 1 was carried out in the same manner as in Example 1, except that the isocyanate adhesive Takenate A-50 (manufactured by Mitsui Chemicals) was added in an amount of 3% by mass based on the resin content of polyvinylidene chloride. A barrier film was produced.
The water vapor permeability of this film was almost the same as that of Example 1. That is, a barrier film with good water vapor barrier properties could be obtained.

[Example 6]
In Example 1, Takelac A-310 (manufactured by Mitsui Chemicals, Inc.) and Takenate A-3 (manufactured by Mitsui Chemicals, Inc.) were blended as polyurethane adhesives at a ratio of 5:1 (mass ratio) on the corona-treated surface of the base film. Then, an adhesive diluted with ethyl acetate was applied using a Mayer bar, and then dried using a hot air dryer at 70° C. for 30 seconds to form an adhesive layer with a thickness of 0.1 μm. Thereafter, Liquid A was similarly applied to the surface of the adhesive layer to produce a barrier film.
The water vapor permeability of this film was almost the same as that of Example 1. That is, a barrier film with good water vapor barrier properties could be obtained.

100 Barrier film 101 Polyvinylidene chloride resin layer 103 Base film layer 105 Inorganic layer

Claims (5)

A method for producing a barrier film comprising at least a base film layer and a polyvinylidene chloride resin layer, the method comprising:
A dissolving step of dissolving polyvinylidene chloride resin in an organic solvent to obtain a resin solution;
a precipitation step of aging the resin solution to obtain a precipitate-containing liquid in which at least a portion of the polyvinylidene chloride resin has precipitated;
A method for producing a barrier film, comprising a coating step of coating the precipitate-containing liquid on a base film and drying the organic solvent to form a polyvinylidene chloride resin layer,
A method for producing a barrier film, wherein the precipitate-containing liquid has an absorbance of 0.5 or more at a wavelength of 660 nm, as measured using a spectrophotometer with an optical path length of 1 cm. A method for producing a barrier film according to claim 1, comprising:
In the dissolving step, (i) the polyvinylidene chloride resin is dissolved in an organic solvent consisting of a mixture of a good solvent and a poor solvent, or (ii) the polyvinylidene chloride resin is dissolved in a good solvent. A method for producing a barrier film, in which a poor solvent is added after that. A method for producing a barrier film according to claim 1 or 2, comprising:
The base film includes an inorganic layer containing one or more selected from the group consisting of silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, and aluminum,
In the coating step, the precipitate-containing liquid is coated on the inorganic layer. A method for producing a barrier film according to any one of claims 1 to 3, comprising:
A method for producing a barrier film, wherein a polyurethane adhesive layer is formed between the base film layer and the polyvinylidene chloride resin layer. A method for producing a barrier film according to any one of claims 1 to 4, comprising:
The polyvinylidene chloride resin layer contains one or more selected from the group consisting of isocyanate compounds, silane coupling agents, urethane resins, urea resins, melamine resins, epoxy resins, and alkyd resins. A method for producing a barrier film containing an adhesive component.

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