JP7141603B2 - barrier film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a barrier film, and more particularly, a second deposited inorganic oxide layer, a barrier coat layer, a first deposited inorganic oxide layer, a substrate film, and a third deposited inorganic oxide. and layers in this order.

Conventionally, inorganic oxides such as silicon oxide and aluminum oxide have been formed on film substrates as barrier materials against oxygen, water vapor, etc. by vacuum deposition, sputtering, ion plating, chemical vapor deposition, and the like. A transparent gas barrier film is attracting attention. As a barrier film, a barrier film comprising a metal foil such as aluminum foil has also been used due to its excellent gas barrier properties, but it cannot be used for microwave ovens and is opaque, making it difficult to see the contents. There was a problem of inferiority.

In recent years, paper containers for liquids with excellent gas barrier properties have been developed for filling and packaging liquids such as liquor, juice, mineral water, liquid seasonings and other foods and drinks, and chemical products. Examples of such paper containers for liquids include those formed by forming a laminated paper container material having an outermost layer, a paper base layer, an adhesive layer, a barrier layer and an innermost layer. Here, as the barrier layer, for example, a barrier film or the like in which an inorganic oxide deposited film is provided on one surface of a base film such as a resin film is used (Patent Document 1).

JP-A-2002-154524

However, vapor deposition films of inorganic oxides are inflexible thin films, so cracks and the like are easily generated by heat and pressure applied from the outside during processing such as lamination or box making, impairing gas barrier properties. There was a problem. On the other hand, it has been studied to prevent the occurrence of cracks and the like by providing a gas barrier coating film on the deposited film of inorganic oxide.

In addition, the paper base material used in the laminated material for paper containers is required to have a certain thickness in order to obtain the self-supporting property and strength of the container. However, when a paper base material having a sufficient thickness is laminated with another base material through an adhesive layer, sufficient interlayer adhesion strength is not obtained, and delamination tends to occur. In particular, when a paper substrate is laminated with a gas barrier coating film of a barrier film, sufficient interlaminar adhesive strength cannot be obtained. In the embossing, there is a problem that peeling occurs between the barrier film and the paper substrate in the laminated material, or the resin layer resulting therefrom. In addition, in a system for in-line carton making from a roll-shaped laminated material for paper containers, there was a similar problem of peeling in the processes such as folding, embossing, and cutting. Furthermore, there is a problem that sufficient gas barrier properties are not exhibited thereby.

The present invention has been made in view of the background art described above, and an object thereof is to provide a barrier film having excellent interlayer adhesion and gas barrier properties.

In order to solve the above problems, the present inventors have made intensive studies and found that, in the barrier film, the second inorganic oxide vapor deposition layer, the specific barrier coat layer, the specific first inorganic oxide vapor deposition layer, the base material It has been found that the above problem can be solved by laminating the film and the third inorganic oxide deposition layer in this order. The present invention has been completed based on such findings.

That is, according to one aspect of the present invention,
A barrier film comprising a second vapor deposited inorganic oxide layer, a barrier coat layer, a first vapor deposited inorganic oxide layer, a substrate film, and a third vapor deposited inorganic oxide layer in this order. hand,
The barrier coat layer is a cured film of a hydrolysis product of a metal alkoxide and a water-soluble polymer,
The first inorganic oxide vapor deposition layer is an aluminum oxide vapor deposition film,
A barrier film is provided in which the second vapor deposited inorganic oxide layer and the third vapor deposited inorganic oxide layer are positioned on the outermost surface of the barrier film.

In the above aspect of the present invention, it is preferable that the aluminum oxide deposited film of the first inorganic oxide deposited layer has a thickness of 5 to 15 nm.

In the above aspect of the present invention, the second vapor deposited inorganic oxide layer is preferably a vapor deposited aluminum oxide film.

In the above aspect of the present invention, it is preferable that the third inorganic oxide vapor deposition layer is an aluminum oxide vapor deposition film.

In the above aspect of the present invention, the barrier film is preferably for paper containers.

According to another aspect of the invention,
A paper container lamination comprising an outermost layer, a paper base layer, a first heat-fusible resin layer, a barrier layer, a second heat-fusible resin layer, and an innermost layer in this order. material,
A laminated material for a paper container is provided, wherein the barrier layer comprises the above barrier film.

In another aspect of the present invention, the heat-fusible resin constituting the heat-fusible resin layer is preferably an ethylene polymer having a carboxyl group or an acid anhydride group in its molecule.

In another aspect of the present invention, the second vapor-deposited inorganic oxide layer of the barrier film is in contact with the first heat-fusible resin layer, and the third vapor-deposited inorganic oxide layer of the barrier film is: It is preferably in contact with the second heat-fusible resin layer.

In another aspect of the present invention, a resin layer is provided between the paper base layer and the first heat-fusible resin layer and/or between the second heat-fusible resin layer and the innermost layer. is preferably further provided.

According to yet another aspect of the invention,
A paper container is provided which is formed by box-making the laminated material for a paper container.

ADVANTAGE OF THE INVENTION According to this invention, the barrier film excellent in interlayer adhesion and gas-barrier property can be provided. Moreover, it is possible to provide a laminated material for a paper container using such a barrier film. Furthermore, it is possible to provide a paper container for liquid formed by box-making such a laminated material for a paper container.

1 is a schematic cross-sectional view showing one embodiment of a barrier film of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing one embodiment of the laminated material for paper containers of the present invention;

<Barrier film>
The barrier film according to the present invention comprises a second vapor deposition layer of inorganic oxide, a barrier coat layer, a first vapor deposition layer of inorganic oxide, a substrate film, and a third vapor deposition layer of inorganic oxide in this order. It becomes A barrier film having such a layer structure has excellent interlayer adhesion and gas barrier properties. Such a barrier film can be suitably used as a barrier layer for various containers and the like that require gas barrier properties and strong adhesion. For example, it can be suitably used as a barrier layer for laminated materials for paper containers. .

The barrier film preferably has an oxygen permeability of 2.5 cc/m ² ·day or less, more preferably 1.0 cc/m ² ·day or less, measured in an environment of temperature 23°C and humidity 90 RH%. and more preferably 0.5 cc/m ² ·day or less. If the oxygen permeability of the barrier film satisfies the above numerical range, it has suitable oxygen barrier properties, so that when used as a barrier layer for a paper container, adverse effects on the contents of the paper container can be suppressed. .

The barrier film preferably has a water vapor permeability of 3.0 g/m ² ·day or less, more preferably 1.0 g/m ² ·day or less, still more preferably 0, as measured in accordance with JIS K7129. .5 g/m ² ·day or less. If the water vapor transmission rate of the barrier film satisfies the above numerical range, it has suitable water vapor barrier properties, so that when used as a barrier layer for a paper container, adverse effects on the contents of the paper container can be suppressed. .

The layer structure of the barrier film of the present invention will be described with reference to the drawings. The barrier film 10 shown in FIG. 1 includes a first vapor deposited inorganic oxide layer 13 on one surface of a base film 11, a barrier coat layer 15 on the first vapor deposited inorganic oxide layer 13, and further A second inorganic oxide deposition layer 12 is provided on the barrier coat layer 15 . Also, the third inorganic oxide deposition layer 14 is provided on the other surface of the base film 11 . Each layer constituting the barrier film of the present invention will be described below.

(Base film)
The base film used in the barrier film of the present invention is not particularly limited. A film of resin that can hold well without damaging the film can be used. Specifically, for example, polyolefin resins such as polyethylene resins or polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), poly(meth)acrylic resins, polycarbonate resins, polyvinyl alcohol resins, saponified ethylene-vinyl ester copolymers, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, and polyamide resins such as various nylons. , polyurethane-based resins, acetal-based resins, and cellulose-based resins. In the present invention, among the above resin films, it is particularly preferable to use films of polyester resin, polyolefin resin, or polyamide resin. The substrate film may be an unstretched film of the above resin, or a film of a resin stretched uniaxially or biaxially.

In the present invention, as the film of the above various resins, for example, one or more of the above various resins are used, and the extrusion method, the cast molding method, the T-die method, the cutting method, the inflation method, etc. Using a film-forming method, a method of forming a film from the above-mentioned various resins alone, or a method of forming a multilayer co-extrusion film using two or more of various resins, Films of various resins are produced by methods such as using resins and mixing them before film formation, and further, if necessary, for example, tenter method, tubular method, etc. are used. Various resin films which are uniaxially or biaxially stretched can be used.

In the present invention, the film thickness of various resin films is preferably about 6 to 2000 μm, more preferably about 9 to 100 μm.

One or more of the various resins described above are used, and when the film is formed, for example, the workability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, and separation properties of the film. Various plastic compounding agents and additives can be added for the purpose of improving and modifying formability, flame retardancy, antifungal properties, electrical properties, strength, etc., and the amount to be added is extremely It can be added arbitrarily depending on the purpose, from a trace amount to several tens of percent.

In the above, as general additives, for example, lubricants, cross-linking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, etc. can be used, and further A modifying resin or the like can also be used.

In the present invention, the substrate film may be surface-treated in advance before forming the inorganic oxide deposition film on the substrate film. This can improve the adhesiveness with the inorganic oxide deposition film. Similarly, the deposition layer may be surface-treated to improve adhesion with the gas-barrier coating film. Such surface treatments include corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, and pretreatment such as oxidation treatment using chemicals.

Moreover, a primer coat agent, an undercoat agent, or a vapor deposition anchor coat agent can be arbitrarily applied for surface treatment. Examples of the coating agent include polyester-based resins, polyamide-based resins, polyurethane-based resins, epoxy-based resins, phenol-based resins, (meth)acrylic-based resins, polyvinyl acetate-based resins, and polyolefin-based resins such as polyethylene and polypropylene. A resin composition containing a resin, a copolymer thereof, a modified resin, a cellulose resin, or the like as a main component of the vehicle can be used.

Among such surface treatments, corona treatment and plasma treatment are particularly preferred. For example, as plasma treatment, there is plasma treatment in which surface modification is performed using plasma gas generated by ionizing gas by arc discharge. Inorganic gases such as oxygen gas, nitrogen gas, argon gas, and helium gas can be used as the plasma gas in addition to the above. For example, by performing plasma treatment in-line, it is possible to remove moisture, dust, etc. from the surface of the substrate film and to perform surface treatments such as smoothing and activation of the surface. In addition, plasma treatment can be performed after vapor deposition to improve adhesiveness. In the present invention, plasma discharge treatment is preferably performed in consideration of plasma output, type of plasma gas, supply amount of plasma gas, treatment time, and other conditions. As a method for generating plasma, devices such as DC glow discharge, high frequency discharge, and microwave discharge can be used. Plasma treatment can also be performed by an atmospheric pressure plasma treatment method.

(Inorganic oxide deposition layer)
The deposited layer constituting the barrier film according to the present invention is a deposited film formed by a chemical vapor deposition method (CVD method) or a physical vapor deposition method (PVD method). The barrier film comprises first to third vapor deposition layers of inorganic oxide, the first vapor deposition layer of inorganic oxide mainly exerting a barrier function as a barrier film, and the second and third vapor deposition layers located on both sides of the barrier film. The inorganic oxide deposition layer 3 plays a role of improving the adhesiveness with the heat-fusible resin layer when forming the following laminated material while exhibiting a barrier function.

In the present invention, the first inorganic oxide deposition layer is an aluminum oxide deposition film. In addition, the second and third inorganic oxide deposition layers are not particularly limited, but oxides of silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, yttrium, etc. can be used. In particular, the second and third inorganic oxide deposited layers are preferably deposited films of aluminum oxide or silicon oxide, and more preferably deposited films of aluminum oxide. The compositions of the first to third inorganic oxide deposited layers may be the same or different.

Inorganic oxides are represented by MO _x (wherein M represents an inorganic element, and the value of X varies depending on the inorganic element), such as AlO _x and SiO _X . be. In the present invention, from the viewpoint of interlayer adhesive strength and transparency, when M is aluminum (Al), the value of X is preferably 0.5 to 2.0, and when M is silicon (Si), X is preferably 1-2.

As the first vapor deposition layer of inorganic oxide, it is preferable to form an aluminum oxide vapor deposition film by a physical vapor deposition method because it is easy to handle as a vapor deposition material. An aluminum oxide deposition film formed by physical vapor deposition has excellent adhesion to the surface of a gas barrier coating film.

Physical vapor deposition methods include, for example, physical vapor deposition methods (physical vapor deposition methods, PVD methods) such as a vacuum deposition method, a sputtering method, an ion plating method, and an ion cluster beam method.

Specifically, a vacuum deposition method in which aluminum or its oxide is used as a raw material, heated and vaporized, and deposited on one of the substrate films, for example, aluminum or its oxide is used as a raw material. , an oxidation reaction deposition method in which oxygen is introduced and oxidized to deposit on one of the base films, and a plasma-assisted oxidation reaction deposition method in which the oxidation reaction is further assisted by plasma, etc. to form a deposited film. can be done. As a method for heating the vapor deposition material, for example, a resistance heating method, a high-frequency induction heating method, an electron beam heating method (EB), or the like can be used.

In the present invention, the film thickness of the aluminum oxide deposited film of the first inorganic oxide deposited layer is preferably 5 to 15 nm, more preferably 7 to 12 nm. If the film thickness of the vapor-deposited aluminum oxide film of the first vapor-deposited inorganic oxide layer is within the above range, it is easy to prevent cracks from occurring due to bending during box-making while providing suitable gas barrier properties.

When the second and third inorganic oxide vapor deposition layers are aluminum oxide vapor deposition films, they can be provided in the same manner as the first inorganic oxide vapor deposition layer described above.

When the second and third inorganic oxide vapor deposition layers are silicon oxide vapor deposition films, the silicon oxide vapor deposition films are preferably formed by chemical vapor deposition from the viewpoint of bending resistance and gas barrier properties. Chemical vapor deposition methods include, for example, plasma chemical vapor deposition methods, low-temperature plasma chemical vapor deposition methods, thermal chemical vapor deposition methods, chemical vapor deposition methods such as photochemical vapor deposition methods (Chemical Vapor Deposition methods, CVD method), etc. Specifically, on one side of the base film, a monomer gas for vapor deposition such as an organic silicon compound is used as a raw material, an inert gas such as argon gas or helium gas is used as a carrier gas, and an oxygen supply gas is used. Alternatively, a low-temperature plasma chemical vapor deposition method using oxygen gas or the like and using a low-temperature plasma generator or the like can be used to form a silicon oxide deposition film. As the low-temperature plasma generator, for example, a generator for high-frequency plasma, pulse wave plasma, microwave plasma, or the like can be used. It is preferable to use a high-frequency plasma type generator in that highly active and stable plasma can be obtained.

In the present invention, the vapor deposition monomer gas for the organosilicon compound for forming the silicon oxide vapor deposition film includes, for example, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, vinyltrimethylsilane, methyltrimethylsilane, Hexamethyldisilane, methylsilane, dimethylsilane, trimethylsilane, diethylsilane, propylsilane, phenylsilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, octa Methylcyclotetrasiloxane and the like can be used. Among these, it is particularly preferable to use 1,1,3,3-tetramethyldisiloxane or hexamethyldisiloxane as the raw material from the viewpoints of handleability, characteristics of the formed continuous film, and the like. In addition, in the above, as inert gas, argon gas, helium gas, etc. can be used, for example.

In the present invention, the vapor-deposited film of silicon oxide is mainly composed of silicon oxide, and furthermore, at least one kind of compound composed of one or more elements of carbon, hydrogen, silicon or oxygen is chemically bonded. It may be contained by, for example. For example, in the case of a compound having a C—H bond, a compound having an Si—H bond, or a carbon unit having a graphitic, diamond-like, fullerene-like, etc., an organosilicon compound or a derivative thereof as a raw material is added. It may be contained by chemical bonding or the like. Examples thereof include hydrocarbons having a CH ₃ moiety, hydrosilica such as SiH ₃ silyl and SiH ₂ silylene, and hydroxyl group derivatives such as SiH ₂ OH silanol. In addition to the above, it is possible to change the type, amount, etc. of the compound contained in the silicon oxide deposited film by changing the conditions of the deposition process.

In the present invention, the film thickness of the second and third inorganic oxide deposition layers is preferably 1 to 50 nm, more preferably 5 to 20 nm. If the film thickness of the second and third inorganic oxide deposition layers is within the above range, the barrier film of the present invention is excellent in adhesiveness to the heat-sealable resin described below while providing suitable gas barrier properties. The laminated material provided has excellent interlayer adhesion.

(Barrier coat layer)
The barrier coat layer is a layer having gas barrier properties, and is preferably a coating film. Furthermore, the barrier coat layer is preferably a cured film of a hydrolysis product of metal alkoxide and a water-soluble polymer. The barrier coat layer can be formed of, for example, the following gas barrier coating film. The gas barrier coating film is a coating film that maintains gas barrier properties in a hot and humid environment, and has the general formula R ¹ _n M (OR ² ) _m (wherein R ¹ and R ² have 1 to 1 carbon atoms). 8 represents an organic group, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the valence of M.) A gas barrier composition containing at least one metal alkoxide and a water-soluble polymer, and further polycondensed by a sol-gel method in the presence of a sol-gel catalyst, acid, water, and an organic solvent. It is a coating film.

In the general formula R ¹ _n M(OR ² ) _m , R ¹ is an optionally branched alkyl group having 1 to 8 carbon atoms, preferably 1 to 5 carbon atoms, more preferably 1 to 4 carbon atoms. , for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-hexyl group, n-octyl group, etc. can be mentioned.

In the general formula R ¹ _n M(OR ² ) _m , R ² is an optionally branched alkyl group having 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms, particularly preferably 1 to 4 carbon atoms. Examples include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group and the like. When multiple (OR ² ) are present in the same molecule, the (OR ² ) may be the same or different.

Examples of metal atoms represented by M in the general formula R ¹ _n M(OR ² ) _m include silicon, zirconium, titanium, and aluminum.

As the alkoxide represented by the general formula R ¹ _n M(OR ² ) _m , at least one kind of partial hydrolyzate of alkoxide and hydrolytic condensate of alkoxide can be used. The partial hydrolyzate is not limited to those in which all of the alkoxy groups are hydrolyzed, and may be those in which one or more of the alkoxy groups are hydrolyzed, or mixtures thereof, and condensates of hydrolysis. As the partially hydrolyzed alkoxide, a dimer or higher, specifically a dimer to a hexamer may be used.

In the present invention, alkoxysilanes in which M is Si can be preferably used as the alkoxide represented by the general formula R ¹ _n M(OR ² ) _m . Suitable alkoxysilanes include, for example, tetramethoxysilane Si( _OCH3 ) ₄ , tetraethoxysilane Si _{( OC2H5} ) ₄ , tetrapropoxysilane Si( _OC3H7 ) ₄ , tetrabutoxysilane Si _{( OC4} H ₉ ) ₄ , methyltrimethoxysilane CH ₃ Si(OCH ₃ ) ₃ , methyltriethoxysilane CH ₃ Si(OC ₂ H ₅ ) ₃ , dimethyldimethoxysilane (CH ₃ ) ₂ Si(OCH ₃ ) ₂ , dimethyldimethoxysilane (CH 3 ) 2 Si(OCH 3 ) 2 ethoxysilane (CH ₃ ) ₂ Si(OC ₂ H ₅ ) ₂ and the like. Condensation products of these alkoxysilanes can also be used in the present invention. Specifically, for example, polytetramethoxysilane, polytetraemethoxysilane, and the like can be used.

In the present invention, a zirconium alkoxide in which M is Zr can also be suitably used as the alkoxide represented by the general formula R ¹ _n M(OR ² ) _m . Suitable zirconium alkoxides include, for example, tetramethoxyzirconium Zr(OCH3) ₄ , tetraethoxyzirconium Zr _{( OC2H5} ) ₄ , tetra-i- _{propoxyzirconium} Zr(iso- _OC3H7 ) ₄ , tetra-n- _{butoxyzirconium} Zr _{(OC4H9)4 etc. can} be illustrated.

As the alkoxide represented by the general formula R ¹ _n M(OR ² ) _m , titanium alkoxide in which M is Ti can also be suitably used. Suitable titanium alkoxides include, for example, tetramethoxytitanium Ti(OCH3) ₄ , tetraethoxytitanium Ti _{( OC2H5} ) ₄ , tetraisopropoxytitanium Ti(iso _{-OC3H7)4 , tetra} - _{nbutoxytitanium} Ti _{(OC4H9)4 etc. can} be illustrated.

As the alkoxide represented by the general formula R ¹ _n M(OR ² ) _m , an aluminum alkoxide in which M is Al can also be preferably used. Suitable aluminum alkoxides include, for example, tetramethoxyaluminum Al(OCH ₃ ) ₄ , tetraethoxyaluminum Al(OC ₂ H ₅ ) ₄ , tetraisopropoxyaluminum Al(iso-OC ₃ H ₇ ) ₄ , tetra-n-butoxyaluminum Al _{(OC4H9)4 etc. can} be illustrated.

In the present invention, the above alkoxides may be used in combination of two or more. For example, when alkoxysilane and zirconium alkoxide are mixed and used, the toughness, heat resistance, etc. of the resulting barrier film can be improved. Further, when alkoxysilane and titanium alkoxide are mixed and used, the thermal conductivity of the resulting gas-barrier coating film is lowered and the heat resistance is remarkably improved.

The water-soluble polymer used in the present invention may be a polyvinyl alcohol resin or an ethylene/vinyl alcohol copolymer alone, or may be a polyvinyl alcohol resin and an ethylene/vinyl alcohol copolymer. Combines can be used in combination. In the present invention, physical properties such as gas barrier properties, water resistance, weather resistance, etc. can be remarkably improved by using a polyvinyl alcohol resin and/or an ethylene/vinyl alcohol copolymer.

As polyvinyl alcohol-based resins, those obtained by saponifying polyvinyl acetate can generally be used. The polyvinyl alcohol resin may be a partially saponified polyvinyl alcohol resin in which several tens of percent of acetic acid groups remain, a fully saponified polyvinyl alcohol in which no acetic acid groups remain, or a modified polyvinyl alcohol resin in which OH groups have been modified. Well, not particularly limited.

As the ethylene/vinyl alcohol copolymer, a saponified copolymer of ethylene and vinyl acetate, that is, a product obtained by saponifying an ethylene-vinyl acetate random copolymer can be used. Examples include partially saponified products in which several tens of mol % of acetic acid groups remain, to complete saponified products in which only several mol % of acetic acid groups or no acetic acid groups remain, and are not particularly limited. However, from the viewpoint of gas barrier properties, it is preferable to use those having a degree of saponification of 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more. The content of repeating units derived from ethylene in the ethylene/vinyl alcohol copolymer (hereinafter also referred to as "ethylene content") is usually 0 to 50 mol%, preferably 20 to 45 mol%. is preferred.

Also, a silane coupling agent may be added to the barrier coat layer. For example, silane coupling agents having reactive groups such as alkoxy groups such as methoxy groups and ethoxy groups, acetoxy groups, amino groups and epoxy groups can be used.

Furthermore, as the organic solvent used in the gas barrier composition, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butanol and the like can be used. The polyvinyl alcohol-based resin and/or the ethylene/vinyl alcohol copolymer is preferably handled in a dissolved state in a coating solution containing the alkoxide, silane coupling agent, or the like. It can be selected as appropriate. For example, when a polyvinyl alcohol resin and an ethylene-vinyl alcohol copolymer are used in combination, it is preferable to use n-butanol.

A barrier coat layer can be manufactured by the following method. First, the above metal alkoxide and, if necessary, a silane coupling agent, a water-soluble polymer, a sol-gel process catalyst, an acid, water, an organic solvent, etc. are mixed to prepare a gas barrier composition (barrier coating liquid).

Next, the gas-barrier composition is applied onto the first vapor-deposited inorganic oxide layer. The method of applying the gas barrier composition includes, for example, coating means such as roll coating such as a gravure roll coater, spray coating, spin coating, dipping, brush, bar code, and applicator, and can be applied once or multiple times. A coating film having a dry film thickness of 0.01 to 30 μm, preferably 0.1 to 10 μm can be formed.

Then, the film coated with the gas barrier composition is heated and dried at a temperature of 20° C. to 200° C. and a temperature not higher than the melting point of the deposited film, preferably a temperature in the range of 50° C. to 180° C., for 10 seconds to 10 minutes. . By this, polycondensation is performed and a barrier coat layer can be formed. In addition, the gas barrier composition is coated on the first vapor deposition layer of inorganic oxide to form two or more coating layers, and the temperature is 20° C. to 200° C. and the melting point of the resin base material or less. A composite polymer layer in which two or more gas barrier coating films are laminated may be formed by heating and drying at a temperature for 10 seconds to 10 minutes. As described above, one to two or more barrier coat layers can be formed from the gas barrier composition.

<Laminated material>
The laminated material of the present invention comprises an outermost layer, a paper base layer, a first heat-fusible resin layer, a barrier layer made of the barrier film, a second heat-fusible resin layer, and an innermost layer. and in this order. Since the laminated material of the present invention has such a layer structure, it has excellent interlayer adhesion between the first heat-fusible resin layer and the barrier layer and between the barrier layer and the second heat-fusible resin layer. and excellent gas barrier properties. Therefore, the laminated material of the present invention can be suitably used as a laminated material for various containers that require gas barrier properties and strong adhesiveness, and can be suitably used as a laminated material for paper containers, for example.

The adhesive strength required between the barrier film and the heat-sealable resin in the laminated material for paper containers is 1.5 N/15 mm or more, preferably 2.0 N/15 mm or more on the paper substrate side, and on the content side. is 3.0 N/15 mm or more, preferably 3.5 N/15 mm or more. With this adhesive strength, it is possible to punch out the laminated material for paper containers on a blank plate, emboss for molding ruled lines for folding, peel off the barrier film and paper base material or resin layer in the laminated material, or roll paper. It is possible to reduce peeling in processes such as folding, embossing, and cutting in a system for in-line carton making from laminated container materials.

The layer structure of the laminated paper container material of the present invention will be described with reference to the drawings. The laminate material 20 for a paper container shown in FIG. , a second heat-fusible resin layer 25, a resin layer 26, and an innermost layer 27 in this order. The second vapor-deposited inorganic oxide layer 12 of the barrier film 10 is in contact with the first heat-fusible resin layer 24, and the third vapor-deposited inorganic oxide layer 14 of the barrier film 10 is the second heat-fusible resin. Alternatively, the second inorganic oxide deposition layer 12 of the barrier film 10 may be in contact with the second heat-sealable resin layer 25 and the third inorganic oxide deposition layer of the barrier film 10 may be in contact with the layer 25 . The layer 14 may be configured to be in contact with the first heat-fusible resin layer 24 . Each layer constituting the laminated material for a paper container of the present invention will be described below.

(outermost layer)
In the laminated material for a paper container of the present invention, a thermoplastic resin can be used as the outermost layer. Specifically, for example, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymer polymerized using a metallocene catalyst, polypropylene, ethylene - vinyl acetate copolymers, ionomer resins, ethylene-acrylic acid copolymers, ethylene-ethyl acrylate copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-propylene copolymers , Methylpentene polymer, polybutene polymer, polyolefin resin such as polyethylene or polypropylene modified with unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid Acid-modified polyolefin resin, poly Resins such as vinyl acetate-based resins, poly(meth)acrylic-based resins, and polyvinyl chloride-based resins can be used.

In the present invention, one or more of the above thermoplastic resins are melt-extruded onto the paper substrate layer, optionally through an anchor coat layer or the like, using an extruder or the like to form the outermost layer. can be done. Alternatively, by using one or more of the above thermoplastic resins, a film or sheet of the resin is produced in advance, and the produced film or sheet is placed on the paper base layer via an adhesive layer for lamination or the like. can also be dry-laminated to form the outermost layer.

In the present invention, the thickness of the outermost layer is preferably about 5-200 μm, more preferably about 10-100 μm.

(Paper base layer)
In the laminated material for a paper container of the present invention, any paper base material can be used as the paper base material layer depending on the application. In particular, in order to make a box and use it as a paper container for liquids, it is necessary to use a paper substrate having sufficiently high formability, bending resistance, rigidity, stiffness and strength. Such paper substrates include, for example, strong sizing bleached or unbleached paper substrates, or various paper substrates such as pure white roll paper, kraft paper, paperboard, processed paper, etc. Those having a basis weight of about 80 to 600 g/m ² , preferably about 100 to 450 g/m ² can be suitably used.

In addition, the paper base material of the paper container for liquid needs to have a certain thickness so as to give sufficient strength to accommodate the liquid. Since the barrier film for paper containers of the present invention can adhere to such thick paper substrates with high interlaminar adhesive strength, paper containers made of this film can be used in various packaging applications for containing liquids. It can be suitably used for Moreover, it can be a form that can stand on its own, such as a cube.

As a method for laminating the paper substrate layer on the first heat-fusible resin layer, one or more of the above thermoplastic resins may be extruded for lamination, or may be laminated via an adhesive or the like. may be dry laminated.

(Heat-fusible resin layer)
In the laminated material for a paper container of the present invention, an ethylene polymer having a carboxyl group or an acid anhydride group in the molecule is preferably used as the heat-fusible resin constituting the heat-fusible resin layer. The ethylene-based polymer can exhibit excellent interlaminar adhesion when in contact with the second and third vapor-deposited inorganic oxide layers of the barrier film.

Examples of the ethylene-based polymer include copolymers of ethylene and unsaturated carboxylic acids or their anhydrides. The unsaturated carboxylic acid or its anhydride is a compound having at least one carboxyl group or acid anhydride group in the molecule, specifically acrylic acid, methacrylic acid, maleic acid, maleic anhydride. , itaconic acid, itaconic anhydride, fumaric acid, crotonic acid and the like. A copolymer of ethylene and acrylic acid or methacrylic acid is particularly preferably used in order to obtain good adhesion to the vapor-deposited film of the inorganic oxide.

In the above ethylene-based copolymer, the ratio of ethylene and unsaturated carboxylic acid or its anhydride, the melt flow rate (MFR), etc. are appropriately determined by those skilled in the art according to the properties of the paper base material used. can do. Generally, in order to increase the adhesion between the heat-fusible resin layer and the barrier film, it is preferable that the proportion of the unsaturated carboxylic acid or its anhydride in the ethylene-based copolymer is high. In the present invention, the ratio of unsaturated carboxylic acid or its anhydride in the ethylene-based copolymer is 3% to 9% by bonding the heat-sealable resin layer through the inorganic oxide deposition layer on the barrier film. Sufficient adhesive strength can be achieved even with a low ratio of about 10%.

In the present invention, the thickness of the heat-fusible resin layer is preferably about 1 to 50 μm, more preferably about 3 to 20 μm, from the viewpoint of film-forming properties and adhesion.

(innermost layer)
In the laminated material for a paper container of the present invention, a resin having heat sealability can be used as the innermost layer. Specifically, the same resin as the outermost layer described above can be used.

The innermost layer can be provided on the surface of the second heat-fusible resin layer by using one or more of the above thermoplastic resins and melt extruding them with an extruder or the like. Alternatively, a film or sheet of one or more of the thermoplastic resins described above is used to produce a film or sheet of the resin in advance, and the produced film or sheet is placed through an adhesive layer for lamination, etc. Dry lamination may be performed on the surface of the second heat-fusible resin layer. If desired, the lamination surface may be previously subjected to various surface treatments such as application of an anchor coating agent.
Also, one or more resin layers may be provided between the innermost layer and the second heat-fusible resin layer by extruding one or more of the above thermoplastic resins.

Low-density polyethylene can be suitably used to form the innermost layer of the present invention, and particularly preferably linear low-density polyethylene polymerized using a metallocene catalyst is used. can. Since these resins exhibit low-temperature sealing properties, they can prevent the occurrence of cracks or the like due to an excessive heat load applied to the vapor-deposited film of the inner layer during lamination or box-making. In addition, it has the advantage of preventing the occurrence of pinholes and avoiding seal failure, liquid leakage, and the like. Other resins may be blended with the above resins to obtain desired properties. In addition, various additives such as antioxidants, ultraviolet absorbers, antistatic agents, antiblocking agents, lubricants (fatty acid amides, etc.), flame retardants, inorganic or organic fillers, dyes, pigments, etc. can be optionally added. can be used as

In the present invention, the thickness of the innermost layer is preferably about 10 μm to 300 μm, more preferably about 20 μm to 100 μm, in order to prevent sealing defects.

<Paper container>
The paper container of the present invention is formed by box-making the laminated material for a paper container, and can be suitably used as a paper container for liquids.

The paper container may be of any type such as, for example, brick type, flat type or gable top type. Moreover, it can be manufactured in any shape, such as a rectangular container, a cylindrical paper can such as a round shape, or the like. The paper container of the present invention can be used to fill and package various articles such as various foods and drinks, chemicals such as adhesives and pressure-sensitive adhesives, cosmetics, miscellaneous goods such as medicines, and the like. In particular, it is useful as a liquid paper container for filling and packaging juices such as alcohol and fruit juice, liquid seasonings such as mineral water, soy sauce, sauces and soups, and various liquid foods such as curry, stew and soup. It is.

The paper container has a volume of 200 mL and an oxygen permeability measured under an environment of temperature 23° C. and humidity 50 RH%, preferably 0.15 cc/pkg day or less, more preferably 0.1 cc/pkg day or less, more preferably 0.03 cc/pkg·day or less. If the oxygen permeability of the paper container satisfies the above numerical range, adverse effects on the contents of the paper container can be suppressed.

The paper container has a water vapor permeability of preferably 0.3 g/pkg·day or less, more preferably 0.1 g/pkg, measured in a 40°C environment with a capacity of 200 mL. · day or less, more preferably 0.05 g/pkg·day or less. If the water vapor transmission rate of the paper container satisfies the above numerical range, the paper container has suitable water vapor barrier properties, so that adverse effects on the contents of the paper container can be suppressed.

(Other aspects)
In another aspect of the present invention, a second vapor deposited inorganic oxide layer, a barrier coat layer, a first vapor deposited inorganic oxide layer, a substrate film, and a third vapor deposited inorganic oxide layer are arranged in this order. A barrier film comprising
The barrier coat layer is a cured film of a hydrolysis product of a metal alkoxide and a water-soluble polymer,
The barrier film, wherein the first vapor-deposited inorganic oxide layer is a vapor-deposited aluminum oxide film.
In the barrier film according to another aspect of the present invention, the aluminum oxide deposited film of the first inorganic oxide deposited layer may have a thickness of 5 to 15 nm.
In the barrier film according to another aspect of the present invention, the second vapor deposition layer of inorganic oxide may be a vapor deposition film of aluminum oxide.
In the barrier film according to another aspect of the present invention, the third inorganic oxide vapor deposition layer may be an aluminum oxide vapor deposition film.
Barrier films according to other aspects of the invention may be for paper containers.
In another aspect of the present invention, an outermost layer, a paper base layer, a first heat-fusible resin layer, a barrier layer, a second heat-fusible resin layer, and an innermost layer are arranged in this order. A laminated material for a paper container, comprising:
The barrier layer is a laminated material for a paper container comprising the barrier film.
In the laminated material for a paper container according to another aspect of the present invention, the heat-fusible resin constituting the heat-fusible resin layer is an ethylene polymer having a carboxyl group or an acid anhydride group in the molecule, good too.
In the laminated material for paper containers according to another aspect of the present invention, the second inorganic oxide deposition layer of the barrier film is in contact with the first heat-fusible resin layer,
A third inorganic oxide deposition layer of the barrier film may be in contact with the second heat-fusible resin layer.
In the laminated material for a paper container according to another aspect of the present invention, between the paper base layer and the first heat-fusible resin layer and/or between the second heat-fusible resin layer and the innermost layer A resin layer may be further provided between them.
Another aspect of the present invention is a paper container formed by box-manufacturing the laminated material for a paper container.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

<Manufacture of barrier film and laminated material>
[Example 1]
A biaxially stretched polyethylene terephthalate (PET) film having a thickness of 12 μm was prepared as a base film. Using a continuous vapor deposition film forming apparatus in which a pretreatment section in which a plasma pretreatment apparatus is arranged on the surface of the PET film on which a vapor deposition layer is to be formed and a film formation section are separated, plasma supply nozzles are used under the following plasma conditions in the pretreatment section. Plasma is introduced from the outlet, plasma pretreatment is performed at a conveying speed of 600 m / min, and then, in the film formation section where it is continuously conveyed, under the following conditions, on the plasma processing surface, as a heating means for the vacuum deposition method, by a reactive resistance heating method , an aluminum oxide deposition film (first inorganic oxide deposition layer) having a thickness of 9.4 nm was formed.
(Plasma pretreatment conditions)
・Plasma intensity: 150 W・sec/m ²
- Plasma forming gas: argon 1200 (sccm), oxygen 3000 (sccm)
・Magnetism forming means: 1000 gauss permanent magnet ・Applied voltage between pretreatment drum and plasma supply nozzle: 340V
・Vacuum degree of pretreatment section: 3.8 Pa
(Aluminum oxide deposition conditions)
・ Degree of vacuum: 8.1 × 10 ^-2 Pa

Further, according to the composition shown in Table 1, the previously prepared hydrolyzate of composition B was added to the mixed solution of composition A prepared in advance, and the mixture was stirred to obtain a colorless and transparent gas barrier composition.

Next, the vapor-deposited aluminum oxide film of the PET film was coated with the gas barrier composition prepared above by a direct gravure method. After that, heat treatment was performed at 140° C. for 60 seconds to form a gas barrier coating film having a thickness of 0.3 μm (in a dry state).

Next, on the gas barrier coating film, using a continuous vapor deposition film forming apparatus in which a pretreatment section in which a plasma pretreatment apparatus is arranged and a film formation section are separated, a plasma supply nozzle is applied under the following plasma conditions in the pretreatment section. Plasma is introduced from the center, plasma pretreatment is performed at a conveying speed of 600 m / min, and then in the film formation section where the film is continuously conveyed, a reactive resistance heating method is used as a heating means for the vacuum deposition method on the plasma processing surface. An aluminum oxide deposition film (second inorganic oxide deposition layer) of 8 nm was formed.

Subsequently, on the other surface of the PET film, using a continuous vapor deposition film forming apparatus in which the pretreatment section in which the plasma pretreatment apparatus is arranged and the film forming section are separated, plasma is supplied under the following plasma conditions in the pretreatment section. Plasma was introduced from a nozzle, and plasma pretreatment was performed at a transport speed of 600 m/min. An aluminum oxide vapor deposition film (third inorganic oxide vapor deposition layer) having a thickness of 8 nm is formed to form a barrier film 1 (layer structure: "second inorganic oxide vapor deposition layer/barrier coat layer/first inorganic oxide vapor deposition layer"). Layer/Base Film/Third Inorganic Oxide Deposited Layer") was obtained.

An ethylene-methacrylic acid copolymer (EMAA, manufactured by DuPont Mitsui Polychemicals Co., Ltd.: Nucrel N-0908C) ( Extrusion temperature: 290°C, extrusion film thickness: 15 µm) was melt extruded to form a first heat-fusible resin layer. In addition, on the other aluminum oxide vapor deposition film (third inorganic oxide vapor deposition layer) of the barrier film 1, an ethylene/methacrylic acid copolymer (EMAA, manufactured by DuPont Mitsui Polychemical Co., Ltd.: Nuclell N-0908C) (extrusion Temperature: 290°C, Extrusion film thickness: 15 µm) was melt extruded to form a second heat-fusible resin layer to obtain a lamination intermediate.

Subsequently, the second heat-fusible resin layer surface of the lamination intermediate and the ethylene-α/olefin copolymer film (m-PEF) (thickness 15 μm) serving as the innermost layer were laminated by a sandwich lamination method, It was laminated via low density polyethylene (extrusion temperature: 300°C, extrusion film thickness: 15 µm).

In addition, one surface of the paper substrate (thickness: 200 g/m) was subjected to corona discharge treatment, and then a low-density polyethylene resin (extrusion temperature: 300°C, extrusion film thickness: 15 µm) was applied to the corona discharge treatment surface. It was melt extruded to form the outermost layer. Subsequently, the first heat-fusible resin layer surface of the lamination intermediate and the other surface of the paper substrate are laminated via a low-density polyethylene (extrusion film thickness: 15 μm) by a sandwich lamination method. , Laminated material 1 (layer structure: "outermost layer / paper base layer / resin layer / first heat-fusible resin layer / barrier film 1 (second inorganic oxide vapor deposition layer / barrier coat layer / first Inorganic oxide deposited layer/base film/third inorganic oxide deposited layer)/second heat-fusible resin layer/resin layer/innermost layer") was obtained.

[Example 2]
A barrier film 2 was prepared in the same manner as in Example 1, except that the thickness of the aluminum oxide vapor deposition film (first inorganic oxide vapor deposition layer) formed on the base film was changed from 9.4 nm to 11.8 nm. Obtained.

Subsequently, a laminated material 2 was obtained in the same manner as in Example 1 except that the barrier film 1 was changed to the barrier film 2.

[Example 3]
Same as Example 1, except that the aluminum oxide vapor deposition film (third inorganic oxide vapor deposition layer) of the barrier film 1 was subjected to corona treatment (2 kW) and then the second heat-sealable resin layer was formed. Then, a laminated material 3 was obtained.

[Example 4]
A first heat-fusible resin layer was formed on the third vapor-deposited inorganic oxide layer of the barrier film 1, and a second heat-fusible resin layer was formed on the second vapor-deposited inorganic oxide layer. Laminated material 4 (layer structure: "outermost layer/paper base layer/resin layer/first heat-fusible resin layer/barrier film 1 (third inorganic oxide Deposited layer/base film/first inorganic oxide deposited layer/barrier coat layer/second inorganic oxide deposited layer)/second heat-fusible resin layer/resin layer/innermost layer") was obtained. .

[Comparative Example 1]
A barrier film 3 was obtained in the same manner as in Example 1, except that the third inorganic oxide deposition layer was not formed.

Subsequently, a laminated material 5 was obtained in the same manner as in Example 1 except that the barrier film 1 was changed to the barrier film 3.

[Comparative Example 2]
A barrier film 4 was obtained in the same manner as in Example 1, except that the second vapor deposited inorganic oxide layer and the third vapor deposited inorganic oxide layer were not formed.

Subsequently, a laminated material 6 was obtained in the same manner as in Example 1 except that the barrier film 1 was changed to the barrier film 4.

[Comparative Example 3]
Except that the second heat-sealable resin layer was formed after corona treatment (2 kW) was applied to the other surface of the PET film of the barrier film 4 (the surface not provided with the third inorganic oxide deposition layer). obtained a laminated material 7 in the same manner as in Comparative Example 2.

[Comparative Example 4]
Except that the second heat-sealable resin layer was formed after corona treatment (6 kW) was applied to the other surface of the PET film of the barrier film 4 (the surface not provided with the third inorganic oxide deposition layer). obtained a laminated material 8 in the same manner as in Comparative Example 2.

<Performance evaluation of barrier film and laminated material>
The following measurements were performed on the barrier films and laminated materials produced in the above examples and comparative examples.

(Measurement of interlayer adhesive strength)
For the laminated intermediates having the first and second heat-sealable resin layers on both sides in the above examples and comparative examples, peeling was performed using a tensile tester (Tensilon universal tester RTC1310A, manufactured by Orientec). A 90° peel test was performed at a speed of 50 mm/min to measure the peel strength (N/15 mm) of the interface between the first heat-fusible resin layer and the barrier film. Similarly, the peel strength (N/15 mm) at the interface between the barrier film and the second heat-fusible resin layer was measured. Table 2 shows the measurement results.

(Measurement of oxygen permeability)
The barrier films produced in the above Examples and Comparative Examples were measured according to JIS K 7126 using a measuring machine (model name: OXTRAN) manufactured by MOCON, USA under the conditions of a temperature of 23°C and a humidity of 90% RH. Oxygen permeability (cc/m ² ·day) was measured according to the above. Table 2 shows the measurement results.

(Measurement of water vapor permeability)
Regarding the barrier films produced in the above Examples and Comparative Examples, the water vapor transmission rate was measured in accordance with JIS K 7129 using a measuring machine (model name: OXTRAN) manufactured by MOCON, USA. All of the barrier films produced in Examples and Comparative Examples were 1.0 g/m ² ·day or less.

The laminated materials produced in the above examples and comparative examples were box-formed to produce 200 mL brick-type paper containers. The obtained paper container was attached with a sealing jig connected to a measuring machine (model name: OXTRAN) manufactured by MOCON in the United States under an environment of a temperature of 23°C and a humidity of 50% RH. Incoming oxygen permeability (cc/pkg·day) was measured. Table 2 shows the measurement results.

REFERENCE SIGNS LIST 10 barrier film 11 base film 12 second vapor deposition layer of inorganic oxide 13 first vapor deposition layer of inorganic oxide 14 third vapor deposition layer of inorganic oxide 15 barrier coat layer 20 laminated material for paper container 21 paper base layer 22 Outermost layer 23 resin layer 24 first heat-fusible resin layer 25 second heat-fusible resin layer 26 resin layer 27 innermost layer

Claims (9)

A paper container barrier comprising a second vapor deposition layer of inorganic oxide, a barrier coat layer, a first vapor deposition layer of inorganic oxide, a substrate film, and a third vapor deposition layer of inorganic oxide in this order. a film,
The barrier coat layer is a cured film of a hydrolysis product of a metal alkoxide and a water-soluble polymer,
The first inorganic oxide vapor deposition layer is an aluminum oxide vapor deposition film,
A barrier film for a paper container , wherein the second vapor-deposited inorganic oxide layer and the third vapor-deposited inorganic oxide layer are positioned on the outermost surface of the barrier film for a paper container . 2. The barrier film for a paper container according to claim 1, wherein the vapor-deposited aluminum oxide film of said first vapor-deposited inorganic oxide layer has a thickness of 5 to 15 nm. 3. The barrier film for a paper container according to claim 1, wherein said second vapor deposition layer of inorganic oxide is a vapor deposition film of aluminum oxide. The barrier film for a paper container according to any one of claims 1 to 3, wherein the third vapor deposited inorganic oxide layer is a vapor deposited aluminum oxide film. A paper container lamination comprising an outermost layer, a paper base layer, a first heat-fusible resin layer, a barrier layer, a second heat-fusible resin layer, and an innermost layer in this order. material,
A laminated material for a paper container, wherein the barrier layer comprises the barrier film for a paper container according to any one of claims 1 to 4 . 6. The paper container laminated material according to claim 5 , wherein the heat-fusible resin constituting the heat-fusible resin layer is an ethylene polymer having a carboxyl group or an acid anhydride group in the molecule. The second inorganic oxide deposition layer of the paper container barrier film is in contact with the first heat-sealable resin layer,
The laminated material for paper containers according to claim 5 or 6 , wherein the third inorganic oxide deposition layer of the barrier film for paper containers is in contact with the second heat-sealable resin layer. 6. A resin layer is further provided between said paper base layer and said first heat-fusible resin layer and/or between said second heat - fusible resin layer and said innermost layer. 8. The laminated material for a paper container according to any one of 1 to 7 . A paper container obtained by box-manufacturing the laminated material for a paper container according to any one of claims 5 to 8 .

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