JP6977534B2 - Barrier film - Google Patents

Description

The present invention relates to a barrier film, and more specifically, a second inorganic oxide-deposited layer, a barrier coat layer, a first inorganic oxide-deposited layer, a base film, and a third inorganic oxide-deposited layer. The present invention relates to a barrier film having layers in this order.

Conventionally, as a barrier material against oxygen or water vapor, an inorganic oxide such as silicon oxide or aluminum oxide is formed on a film substrate by a vacuum vapor deposition method, a sputtering method, an ion plating method, a chemical vapor deposition method, or the like. The transparent gas barrier film is attracting attention. As a barrier film, a barrier film provided with a metal foil such as aluminum foil has been conventionally used because it has excellent gas barrier properties, but it cannot be used for microwave ovens or is opaque, so that the contents can be viewed easily. There was a problem of being inferior.

Further, in recent years, liquid paper containers having excellent gas barrier properties have been developed for filling and packaging liquids such as alcoholic beverages, juices, mineral waters, foods and drinks such as liquid seasonings, and chemical products. Examples of such a liquid paper container include those made by manufacturing a laminated material for a paper container having an outermost layer, a paper base material 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 a vapor-deposited film of an inorganic oxide is provided on one surface of a base film such as a resin film is used (Patent Document 1).

Japanese Unexamined Patent Publication No. 2002-154524

However, since the thin-film inorganic oxide film is an inflexible thin film, cracks and the like are easily generated by heat and pressure applied from the outside during processing such as lamination or box making, and the gas barrier property is impaired. 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 vapor-filmed film of the inorganic oxide.

Further, the paper base material used in the laminated material for a paper container is required to have a certain thickness in order to obtain the independence and strength of the container. However, when a paper base material having a sufficient thickness is laminated with another base material via an adhesive layer, sufficient interlayer adhesion strength cannot be obtained and delamination is likely to occur. In particular, when the paper base material is laminated with the gas barrier coating film of the barrier film, sufficient interlayer adhesion strength cannot be obtained, and the laminated material for paper containers in the box making process is punched into a blank plate and ruled line molding for bending. There is a problem that the barrier film in the laminated material and the paper base material or the resin layer caused by the peeling occur due to the embossing. Further, in a system for in-line box making from a roll-shaped laminated material for a paper container, there is a similar problem of peeling in processes such as bending, embossing, and cutting. Further, there is a problem that sufficient gas barrier property is not exhibited due to this.

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

As a result of diligent studies to solve the above problems, the present inventors have made a second inorganic oxide-deposited layer, a specific barrier coat layer, a specific first inorganic oxide-deposited layer, and a base material in the barrier film. It was found that the above-mentioned problems can be solved by laminating the film and the third inorganic oxide-deposited 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 inorganic oxide-deposited layer, a barrier coat layer, a first inorganic oxide-deposited layer, a base film, and a third inorganic oxide-deposited 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.
A barrier film is provided in which the first inorganic oxide-deposited layer is an aluminum oxide-deposited film.

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

In the above aspect of the present invention, it is preferable that the second inorganic oxide-deposited layer is an aluminum oxide-deposited film.

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

In the above aspect of the present invention, it is preferable that the barrier film is for a paper container.

According to another aspect of the invention.
A stack for a paper container, comprising an outermost layer, a paper base material layer, a first heat-sealing resin layer, a barrier layer, a second heat-sealing resin layer, and an innermost layer in this order. It ’s a material,
A laminated material for a paper container is provided in which the barrier layer is made of the above barrier film.

In another aspect of the present invention, it is preferable that the heat-sealing resin constituting the heat-sealing resin layer is an ethylene-based polymer having a carboxyl group or an acid anhydride group in the molecule.

In another aspect of the present invention, the second inorganic oxide-deposited layer of the barrier film is in contact with the first heat-sealing resin layer, and the third inorganic oxide-deposited layer of the barrier film is formed. It is preferable to be in contact with the second heat-sealing resin layer.

In another aspect of the present invention, a resin layer is formed between the paper substrate layer and the first heat-sealing resin layer and / or between the second heat-sealing resin layer and the innermost layer. It is preferable to further prepare.

According to yet another aspect of the invention.
A paper container made by manufacturing the above-mentioned laminated material for a paper container is provided.

According to the present invention, it is possible to provide a barrier film having excellent interlayer adhesion and gas barrier properties. Further, it is possible to provide a laminated material for a paper container using such a barrier film. Further, it is possible to provide a liquid paper container made by manufacturing such a laminated material for a paper container.

It is a schematic sectional drawing which showed one Embodiment of the barrier film of this invention. It is a schematic sectional drawing which showed one Embodiment of the laminated lumber for a paper container of this invention.

<Barrier film>
The barrier film according to the present invention includes a second inorganic oxide-deposited layer, a barrier coat layer, a first inorganic oxide-deposited layer, a base film, and a third inorganic oxide-deposited layer in this order. It becomes. The barrier film having such a layer structure has excellent interlayer adhesiveness and gas barrier property. 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 adhesiveness, and can be suitably used, for example, as a barrier layer for laminated materials for paper containers. ..

The barrier film has an oxygen permeability measured in an environment of a temperature of 23 ° C. and a humidity of 90 RH%, preferably ^2.5 cc / m 2 · day or less, and more preferably 1.0 cc / m ² · day or less. , 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 a suitable oxygen barrier property, and therefore, when it is used as a barrier layer of a paper container, it is possible to suppress an adverse effect on the contents of the paper container. ..

The barrier film has a water vapor transmission rate measured in accordance with JIS K7129, preferably 3.0 g / m ² · day or less, more preferably 1.0 g / m ² · day or less, and even more preferably 0. It is .5 g / m ² · day or less. If the water vapor transmission rate of the barrier film satisfies the above numerical range, it has a suitable water vapor barrier property, and therefore, when it is used as a barrier layer of a paper container, it is possible to suppress an adverse effect on the contents of the paper container. ..

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 is provided with a first inorganic oxide-deposited layer 13 on one surface of the base film 11, a barrier coat layer 15 on the first inorganic oxide-deposited layer 13, and further. A second inorganic oxide-deposited layer 12 is provided on the barrier coat layer 15. Further, a third inorganic oxide vapor deposition layer 14 is provided on the other surface of the base film 11. Hereinafter, each layer constituting the barrier film of the present invention will be described.

(Base film)
The base film used in the barrier film of the present invention is not particularly limited, but has excellent chemical or physical strength, withstands conditions for forming a vapor-filmed inorganic oxide film, and has film characteristics thereof. It is possible to use a resin film that can be held well without damaging the film. Specifically, for example, a polyolefin resin such as a polyethylene resin or a polypropylene resin, a cyclic polyolefin resin, a polystyrene resin, an acrylonitrile-styrene copolymer (AS resin), and an acrylonitrile-butadiene-styrene copolymer (ABS). Resin), poly (meth) acrylic resin, polycarbonate resin, polyvinyl alcohol resin, ethylene-vinyl ester copolymer saponified product, polyester resin such as polyethylene terephthalate and polyethylene naphthalate, polyamide resin such as various nylons. , Polyurethane-based resin, acetal-based resin, cellulose-based resin, and other various resin films can be used. In the present invention, among the above-mentioned resin films, it is particularly preferable to use a polyester-based resin, a polyolefin-based resin, or a polyamide-based resin film. As the base film, any of the above-mentioned unstretched resin film and the uniaxially or biaxially stretched resin film can be used.

In the present invention, as the film of the above-mentioned various resins, for example, one or more of the above-mentioned various resins are used to produce an extrusion method, a cast molding method, a T-die method, a cutting method, an inflation method, or the like. A method of forming a film of the above-mentioned various resins independently by using a film forming method, a method of forming a multilayer co-extruded film using two or more kinds of resins, and further, a method of forming a multi-layer coextruded film using two or more kinds of resins. Various resin films are manufactured by using a resin and mixing before forming a film to form a film, and if necessary, for example, a tenter method or a tubular method is used. Therefore, various resin films stretched in the uniaxial or biaxial directions 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.

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

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

In the present invention, the base film may be surface-treated in advance before forming the inorganic oxide-deposited film on the base film. This makes it possible to improve the adhesiveness with the inorganic oxide vapor deposition film. Similarly, a surface treatment can be performed on the vapor-filmed layer to improve the adhesiveness with the gas barrier coating film. Such surface treatments include pretreatments such as corona discharge treatment, ozone treatment, low temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, and oxidation treatment using chemicals or the like.

Further, a primer coating agent, an undercoating agent, a vapor deposition anchor coating agent, or the like can be arbitrarily applied to perform surface treatment. The coating agent may be, for example, a polyester resin, a polyamide resin, a polyurethane resin, an epoxy resin, a phenol resin, a (meth) acrylic resin, a polyvinyl acetate resin, a polyolefin resin such as polyethylene or polypropylene. A resin composition containing a resin, a copolymer thereof, a modified resin, a cellulose-based resin, or the like as the main component of the vehicle can be used.

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

(Inorganic oxide vapor deposition layer)
The thin-film vapor deposition layer constituting the barrier film according to the present invention is a thin-film deposition film formed by a chemical vapor deposition method (CVD method) or a physical vapor deposition method (PVD method). The barrier film includes first to third inorganic oxide-deposited layers, and the first inorganic oxide-deposited layer mainly exhibits a barrier function as a barrier film, and the second and second barrier films are located on both sides of the barrier film. The inorganic oxide-deposited layer of No. 3 plays a role of improving the adhesiveness with the heat-sealing resin layer when forming the following laminated material while exhibiting a barrier function.

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

The notation of an inorganic oxide is expressed by MO _X (however, in the formula, M represents an inorganic element, and the value of X has a range different depending on the inorganic element) _{such as AlO X} , SiO _{X, etc.).} To. In the present invention, from the viewpoint of interlayer adhesion strength and transparency, the value of X is preferably 0.5 to 2.0 when M is aluminum (Al), and X when M is silicon (Si). The value of is preferably 1 to 2.

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

Examples of the physical vapor deposition method include a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, an ion plating method, and an ion cluster beam method.

Specifically, a vacuum vapor deposition method in which aluminum or an oxide thereof is used as a raw material, which is heated and vaporized, and this is vapor-deposited on one of the base films, for example, aluminum or an oxide thereof is used as a raw material. A vapor deposition film is formed by using an oxidation reaction vapor deposition method in which oxygen is introduced and oxidized to deposit on one of the substrate films, and a plasma-assisted oxidation reaction vapor deposition method in which the oxidation reaction is subsidized by plasma. Can be done. As the heating method for the vapor-filmed 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.

Further, in the present invention, the film thickness of the aluminum oxide vapor deposition film of the first inorganic oxide vapor deposition layer is preferably 5 to 15 nm, more preferably 7 to 12 nm. When the film thickness of the aluminum oxide vapor-deposited film of the first inorganic oxide-deposited layer is within the above range, it is easy to prevent the occurrence of cracks due to bending during box making while having 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-deposited layers are silicon oxide-deposited films, it is preferable to provide the silicon oxide-deposited film by the chemical vapor deposition method from the viewpoint of bending resistance and gas barrier properties. Examples of the chemical vapor deposition method include a chemical vapor deposition method such as a plasma chemical vapor deposition method, a low temperature plasma chemical vapor deposition method, a thermochemical vapor deposition method, and a photochemical vapor deposition method. CVD method) and the like. Specifically, on one surface 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 further used. As a result, a silicon oxide vapor deposition film can be formed by using a low temperature plasma chemical vapor deposition method using an oxygen gas or the like and using a low temperature plasma generator or the like. As the low temperature plasma generator, for example, a generator such as a high frequency plasma, a pulse wave plasma, or a microwave plasma can be used. It is preferable to use a generator by a high frequency plasma method in that a stable plasma with high activity can be obtained.

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

In the present invention, the vapor deposition film of silicon oxide is mainly composed of silicon oxide, but further, at least one kind of a compound composed of one kind or two or more kinds of elements such as carbon, hydrogen, silicon or oxygen is chemically bonded. It may be contained by such as. For example, when the compound having a C—H bond, the compound having a Si—H bond, or the carbon unit is in the form of graphite, diamond, fullerene, etc., the raw material organic silicon compound or a derivative thereof can be further used. It may be contained due to chemical bonds or the like. For example, a hydrocarbon having _{a CH 3} moiety, a hydroxy silica such as _{SiH 3} silyl and SiH _{2 silylene, and a hydroxyl derivative such as SiH 2} OH silanol can be mentioned. In addition to the above, the type, amount, and the like of the compound contained in the silicon oxide vapor deposition film can be changed by changing the conditions of the vapor deposition process.

In the present invention, the film thickness of the second and third inorganic oxide vapor deposition layers is preferably 1 to 50 nm, more preferably 5 to 20 nm. When the thickness of the second and third inorganic oxide vapor-deposited layers is within the above range, the barrier film of the present invention is used because it has a suitable gas barrier property and is excellent in adhesiveness to the following heat-sealing resin. The provided laminated material has excellent interlayer adhesiveness.

(Barrier coat layer)
The barrier coat layer is a layer having a gas barrier property, and is preferably a coating film. Further, the barrier coat layer is preferably a cured film of a hydrolysis product of a metal alkoxide and a water-soluble polymer. The barrier coat layer can be formed by, for example, the following gas barrier coating film. The gas barrier coating film is a coating film that maintains gas barrier properties in a high temperature and high humidity environment, and the general formula R ¹ _n M (OR ² ) _m (however, in the formula, R ¹ and R ² have 1 to 1 carbon atoms. 8 organic groups, 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). From a gas barrier composition containing at least one metal alkoxide and a water-soluble polymer, which is further condensed by the solgel method in the presence of a solgel method catalyst, acid, water, and an organic solvent. It is a coating film.

In the above general formula R ¹ _n M (OR ² ) _m , R ¹ is an alkyl group having 1 to 8 carbon atoms, preferably 1 to 5 and more preferably 1 to 4, which may have a branch. 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 and the like. Can be mentioned.

In the above general formula R ¹ _n M (OR ² ) _m , R ² is an alkyl group having 1 to 8 carbon atoms which may have a branch, more preferably 1 to 5, and particularly preferably 1 to 4 alkyl groups. Yes, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group and the like can be mentioned. When a plurality of (OR ² ) are present in ^{the same molecule, the (OR 2} ) may be the same or different.

Examples of the metal atom represented by M in the above 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 or more of a partial hydrolyzate of the alkoxide and a hydrolyzed condensate of the alkoxide can be used, and the alkoxide of the above alkoxide can be used. The partial hydrolyzate is not limited to one in which all of the alkoxy groups are hydrolyzed, and may be one in which one or more are hydrolyzed and a mixture thereof, and further, a condensate of hydrolysis. As, a dimer or more of the partially hydrolyzed alkoxide, specifically, a 2 to 6-mer may be used.

In the present invention, an alkoxysilane in which M is Si can be preferably used as the alkoxide represented by ^{the above general formula R 1} _n M (OR ² ) _m. Suitable alkoxysilanes include, for example, tetramethoxysilane Si (OCH ₃ ) ₄ , tetraethoxysilane Si (OC ₂ H ₅ ) ₄ , tetrapropoxysilane Si (OC ₃ H ₇ ) ₄ , and tetrabutoxysilane Si (OC _4). 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 , Dimethyldi Examples thereof include ethoxysilane (CH ₃ ) ₂ Si (OC ₂ H ₅ ) _2. In the present invention, polycondensations of these alkoxysilanes can also be used, and specifically, for example, polytetramethoxysilane, polytetraemethoxysilane, and the like can be used.

In the present invention, ^{as the alkoxide represented by the above general formula R 1} _n M (OR ² ) _m , a zirconium alkoxide in which M is Zr can also be preferably used. Suitable zirconium alkoxides include, for example, tetramethoxyzirconium Zr (OCH ₃ ) ₄ , tetraethoxyzirconium Zr (OC ₂ H ₅ ) ₄ , tetra ipropoxyzirconium Zr (iso-OC ₃ H ₇ ) ₄ , tetra n butoxyzirconium. Zr (OC ₄ H ₉ ) _{4 and the} like can be exemplified.

Further, as the alkoxide represented by the above general formula R ¹ _n M (OR ² ) _m , a titanium alkoxide in which M is Ti can also be preferably used. Suitable titanium alkoxides include, for example, tetramethoxytitanium Ti (OCH ₃ ) ₄ , tetraethoxytitanium Ti (OC ₂ H ₅ ) ₄ , tetraisopropoxytitanium Ti (iso-OC ₃ H ₇ ) ₄ , tetran butoxytitanium. Ti (OC ₄ H ₉ ) _{4 and the} like can be exemplified.

Further, as the alkoxide represented by the above 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 (OC ₄ H ₉ ) _{4 and the} like can be exemplified.

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

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

As the polyvinyl alcohol-based resin, one obtained by saponifying polyvinyl acetate can generally be used. The polyvinyl alcohol-based resin may be a partially saponified polyvinyl alcohol-based resin in which several tens of percent of acetic acid groups remain, a completely saponified polyvinyl alcohol in which no acetate group remains, or a modified polyvinyl alcohol-based resin in which an OH group is modified. Well, it is not particularly limited.

As the ethylene-vinyl alcohol copolymer, a saponified product of a copolymer of ethylene and vinyl acetate, that is, a product obtained by saponifying an ethylene-vinyl acetate random copolymer can be used. For example, it includes, and is not particularly limited, from a partially saponified product in which several tens of mol% of acetic acid groups remain to a completely saponified product in which only a few mol% of acetic acid groups remain or no acetic acid groups remain. However, from the viewpoint of gas barrier properties, it is preferable to use a saponification degree of 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more. The content of the repeating unit derived from ethylene in the above ethylene / vinyl alcohol copolymer (hereinafter, also referred to as “ethylene content”) is usually 0 to 50 mol%, preferably 20 to 45 mol%. Is preferable.

Further, a silane coupling material may be added to the barrier coat layer. For example, a silane coupling material having a reactive group such as an alkoxy group such as a methoxy group or an ethoxy group, an acetoxy group, an amino group or an epoxy group can be used.

Further, as the organic solvent used in the above 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 state of being dissolved in a coating liquid containing the alkoxide, a silane coupling agent, or the like, and is preferably handled from the organic solvent. It can be selected as appropriate. For example, when a polyvinyl alcohol-based resin and an ethylene / vinyl alcohol copolymer are used in combination, it is preferable to use n-butanol.

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

Next, the gas barrier composition is applied on the first inorganic oxide vapor deposition layer. As a method of applying the gas barrier composition, for example, a roll coat such as a gravure roll coater, a spray coat, a spin coat, a dipping, a brush, a bar code, an applicator, or the like can be applied once or multiple times. A coating film having a dry film thickness of 0.01 to 30 μm, preferably about 0.1 to 10 μm can be formed.

Next, the film coated with the gas barrier composition is heated and dried at a temperature of 20 ° C. to 200 ° C. and a temperature equal to or lower than the melting point of the vapor-filmed film, preferably in the range of 50 ° C. to 180 ° C. for 10 seconds to 10 minutes. .. As a result, polycondensation is performed and a barrier coat layer can be formed. Further, the gas barrier composition is applied on top of the first inorganic oxide vapor deposition layer, and two or more coating films are laminated, and the temperature is 20 ° C to 200 ° C and the temperature is equal to or lower than the melting point of the resin substrate. It may be heat-dried at a temperature of 10 seconds to 10 minutes to form a composite polymer layer in which two or more layers of gas barrier coating films are layered. As described above, one or two or more barrier coat layers made of the gas barrier composition can be formed.

<Laminate material>
The laminated material of the present invention includes an outermost layer, a paper base material layer, a first heat-sealing resin layer, a barrier layer made of the barrier film, a second heat-sealing resin layer, and an innermost layer. And are prepared 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-sealing resin layer and the barrier layer and between the barrier layer and the second heat-sealing resin layer. Also, it has excellent gas barrier properties. Therefore, the laminated material of the present invention can be suitably used as a laminated material for various containers and the like that require gas barrier properties and strong adhesiveness, and can be suitably used, for example, as a laminated material for paper containers.

The adhesive strength required for the barrier film and the heat-sealing 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 is on the content side. Is 3.0 N / 15 mm or more, preferably 3.5 N / 15 mm or more. With this adhesive strength, punching of the laminated material for paper containers into a blank plate, embossing of ruled line molding for folding, peeling of the barrier film from the paper base material or resin layer in the laminated material, or roll-shaped paper It is possible to reduce peeling in processes such as bending, embossing, and cutting in a system for in-line box making from laminated lumber for containers.

The layer structure of the laminated material for a paper container of the present invention will be described with reference to the drawings. The laminated material 20 for a paper container shown in FIG. 2 includes an outermost layer 22, a paper base material layer 21, a resin layer 23, a first heat-sealing resin layer 24, and a barrier layer barrier film (barrier layer) 10. A second heat-sealing resin layer 25, a resin layer 26, and an innermost layer 27 are provided in this order. The second inorganic oxide vapor deposition layer 12 of the barrier film 10 is in contact with the first heat-sealing resin layer 24, and the third inorganic oxide vapor deposition layer 14 of the barrier film 10 is a second heat-sealing resin. It may be configured to be in contact with the layer 25, or the second inorganic oxide vapor deposition layer 12 of the barrier film 10 may be in contact with the second heat-sealing resin layer 25 and the third inorganic oxide vapor deposition of the barrier film 10. The layer 14 may be configured to be in contact with the first heat-sealing resin layer 24. Hereinafter, each layer constituting the laminated material for a paper container of the present invention will be described.

(Outermost layer)
In the laminated material for paper containers 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 (linear) low-density polyethylene, ethylene-α / olefin copolymer polymerized using a metallocene catalyst, polypropylene, ethylene. -Vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer Acid-modified polyolefin resin, poly, obtained by modifying a polyolefin resin such as methylpentene polymer, polybutene polymer, polyethylene or polypropylene with unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid and itaconic acid. Resins such as vinyl acetate-based resin, poly (meth) acrylic-based resin, and polyvinyl chloride-based resin can be used.

In the present invention, one or more of the above thermoplastic resins are melt-extruded onto a paper substrate layer via an anchor coat layer or the like, if desired, using an extruder or the like to form an outermost layer. Can be done. Alternatively, a film or sheet of the resin is manufactured in advance using the above-mentioned one or more types of thermoplastic resin, and the manufactured film or sheet is placed on the paper substrate layer via an adhesive layer for laminating or the like. It is also possible to form the outermost layer by laminating with a dry laminate.

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

(Paper substrate layer)
In the laminated material for paper containers of the present invention, any paper base material can be used as the paper base material layer depending on the intended use. In particular, in order to make a box and use it as a liquid paper container, it is necessary to use a paper base material having sufficiently high moldability, bending resistance, rigidity, waist and strength. Examples of such a paper base material include a strong-sized bleached or unbleached paper base material, or various paper base materials such as pure white roll paper, kraft paper, paperboard, and processed paper, and have a basis weight. about 80~600g / ^{m 2} about things, preferably, it can be preferably used of about basis weight of about 100~450g / ^{m 2.}

Further, the paper base material of the liquid paper container needs to have a certain thickness so as to be able to impart sufficient strength to contain the liquid. Since the barrier film for a paper container of the present invention can be bonded to such a thick paper base material with high interlayer adhesive strength, the paper container made of this can be used for various packaging for accommodating a liquid. Can be suitably used for. In addition, it can be a self-supporting form such as a cube.

As a method of laminating the paper base material layer on the first heat-sealing resin layer, the paper substrate layer may be laminated by extruding one or more of the above-mentioned thermoplastic resins, or may be laminated via an adhesive or the like. May be dry laminated.

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

Examples of the above-mentioned ethylene-based polymer include a copolymer of ethylene and an unsaturated carboxylic acid or an anhydride thereof. The unsaturated carboxylic acid or its anhydride is a compound having at least one carboxyl group or an acid anhydride group in the molecule, and specifically, acrylic acid, methacrylic acid, maleic acid, maleic anhydride. , Itaconic acid, anhydrous itaconic acid, fumaric acid, crotonic acid and the like. A copolymer of ethylene with acrylic acid or methacrylic acid is particularly preferably used in order to improve the adhesiveness of the inorganic oxide to the vapor-deposited film.

In the above ethylene-based copolymer, the ratio of ethylene to the 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 substrate to be used and the like. can do. Usually, in order to enhance the adhesiveness between the heat-bondable resin layer and the barrier film, it is preferable that the proportion of 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 adhering the heat-bondable resin layer via the inorganic oxide vapor deposition layer on the barrier film. Sufficient adhesive strength can be achieved even at a low ratio of about%.

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

(Innermost layer)
In the laminated material for paper containers of the present invention, a resin having a heat-sealing property 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-sealing resin layer by melt-extruding the above-mentioned one or more types of thermoplastic resin with an extruder or the like. Alternatively, a film or sheet of the resin is manufactured in advance using the above-mentioned film or sheet of one or more types of thermoplastic resin, and the manufactured film or sheet is passed through an adhesive layer for laminating or the like. A dry laminate may be laminated on the surface of the second heat-sealing resin layer side. If desired, various surface treatments such as applying an anchor coating agent in advance may be applied to the laminated surface. Further, one or more resin layers may be provided between the innermost layer and the second thermothermally fused resin layer by extruding the above-mentioned one or more kinds of thermoplastic resins.

In order to form the innermost layer of the present invention, low density polyethylene can be preferably used, and particularly preferably, linear (linear) low density polyethylene polymerized using a metallocene catalyst can be used. can. Since these resins exhibit low-temperature sealing properties, it is possible to prevent cracks and the like from being applied to the vapor-filmed film of the inner layer during laminating or box making. In addition, it has the advantage of preventing the occurrence of pinholes and avoiding sealing defects, liquid leakage, and the like. In order to obtain desired properties, the above resin may be blended with another resin and used. In addition, various additives such as antioxidants, ultraviolet absorbers, antistatic agents, antiblocking agents, lubricants (fatty acid amides, etc.), flame retardant agents, inorganic or organic fillers, dyes, pigments, etc. are arbitrarily added. Can be used.

In the present invention, the film 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 made by manufacturing the above-mentioned laminated material for paper containers, and can be particularly preferably used as a liquid paper container.

The paper container may be any type such as a brick type, a flat type or a Goebel top type. Further, the shape can be any of a square container, a cylindrical paper can such as a round shape, and the like. The paper container of the present invention can be filled and packaged with various articles such as various foods and drinks, chemicals such as adhesives and adhesives, and miscellaneous goods such as cosmetics and pharmaceuticals. In particular, it is useful as a liquid paper container for filling and packaging juices such as liquor and fruit juice beverages, liquid seasonings such as mineral water, soy sauce, sauces and soups, and various liquid foods and drinks such as curry, stew and soup. It is a thing.

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

The paper container has a volume of 200 mL, and the water vapor transmission rate from the inside of the container to the outside of the container measured in an environment of 40 ° C. is preferably 0.3 g / pkg · day or less, more preferably 0.1 g / pkg. -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, it has a suitable water vapor barrier property, so that adverse effects on the contents of the paper container can be suppressed.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

<Manufacturing of barrier films and laminated materials>
[Example 1]
As a base film, a biaxially stretched polyethylene terephthalate (PET) film having a thickness of 12 μm was prepared. Using a continuous vapor deposition film film forming apparatus that separates the pretreatment section and the film formation section in which the plasma pretreatment device is arranged on the surface forming the vapor deposition layer of the PET film, the plasma supply nozzle in the pretreatment section under the following plasma conditions. Plasma was introduced from the film, subjected to plasma pretreatment at a transport speed of 600 m / min, and then, in the film-forming section that was continuously transported, the reactive resistance heating method was used as a heating means for the vacuum vapor deposition method on the plasma-processed surface under the following conditions. , A 9.4 nm thick aluminum oxide vapor deposition film (first inorganic oxide vapor deposition layer) was formed.
(Plasma pretreatment conditions)
・ Plasma intensity: 150 W ・ sec / m ²
-Plasma forming gas: Argon 1200 (sccm), Oxygen 3000 (sccm)
-Magnetic forming means: 1000 gauss permanent magnet-Pretreatment drum-Plasma supply nozzle applied voltage: 340V
-Vacuum degree of pretreatment section: 3.8 Pa
(Aluminum oxide film formation conditions)
-Vacuum degree: 8.1 x 10 ^-2 Pa

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

Next, the gas barrier composition prepared above was coated on the aluminum oxide vapor-deposited film of the PET film by the direct gravure method. Then, it was heat-treated at 140 ° C. for 60 seconds to form a gas barrier coating film having a thickness of 0.3 μm (dry operation state).

Next, using a continuous thin-film deposition film film forming apparatus that separates the pretreatment section and the film formation section in which the plasma pretreatment device is arranged on the gas barrier coating film, the plasma supply nozzle in the pretreatment section under the following plasma conditions. Plasma was introduced from the film, subjected to plasma pretreatment at a transport speed of 600 m / min, and then, in the film-forming section that was continuously transported, the thickness was increased by a reactive resistance heating method as a heating means of the vacuum vapor deposition method on the plasma-processed surface. An 8 nm aluminum oxide vapor deposition film (second inorganic oxide vapor deposition layer) was formed.

Subsequently, plasma is supplied in the pretreatment section under the following plasma conditions by using a continuous vapor deposition film deposition apparatus in which the pretreatment section in which the plasma pretreatment device is arranged and the film formation section are separated on the other surface of the PET film. Plasma is introduced from the nozzle, plasma pretreatment is performed at a transport speed of 600 m / min, and then, in the film formation section that is continuously transported, the thickness is increased by a reactive resistance heating method as a heating means of the vacuum vapor deposition method on the plasma treated surface. A barrier film 1 (layer structure: "second inorganic oxide vapor deposition layer / barrier coat layer / first inorganic oxide vapor deposition" is formed by forming an aluminum oxide vapor deposition film (third inorganic oxide vapor deposition layer) having a thickness of 8 nm. A layer / base film / third inorganic oxide-deposited layer ”) was obtained.

An ethylene / methacrylic acid copolymer (EMAA, manufactured by Mitsui DuPont Polychemical Co., Ltd .: Nuclel N-0908C) (Nuclel N-0908C) (EMAA, manufactured by Mitsui DuPont Polychemical Co., Ltd .: Nuclel N-0908C) on one of the aluminum oxide vapor deposition films (second inorganic oxide vapor deposition layers) of the obtained barrier film 1. Extrusion temperature: 290 ° C., extrusion film thickness: 15 μm) was melt-extruded to form a first heat-sealing resin layer. Further, 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 Mitsui DuPont Polychemical Co., Ltd .: Nuclel N-0908C) (extruded). The temperature: 290 ° C. and the extrusion film thickness: 15 μm) were melt-extruded to form a second heat-sealing resin layer to obtain a laminated intermediate.

Subsequently, the second heat-sealing resin layer surface of the laminated intermediate and the innermost ethylene-α / olefin copolymer film (m-PEF) (thickness 15 μm) were subjected to a sandwich laminating method. Laminated through low density polyethylene (extrusion temperature: 300 ° C., extrusion film thickness: 15 μm).

Further, after corona discharge treatment is applied to one surface of the paper substrate (thickness 200 g / m), a low density polyethylene resin (extrusion temperature: 300 ° C., extrusion film thickness: 15 μm) is applied to the corona discharge treated surface. The outermost layer was formed by melt extrusion. Subsequently, the first heat-sealing resin layer surface of the laminated intermediate and the other surface of the paper substrate are laminated via a low-density polyethylene (extruded film thickness: 15 μm) by a sandwich laminating method. , Laminated material 1 (Layer structure: "Outermost layer / Paper substrate layer / Resin layer / First heat-sealing resin layer / Barrier film 1 (Second inorganic oxide vapor deposition layer / Barrier coat layer / First Inorganic oxide vapor deposition layer / base film / third inorganic oxide vapor deposition layer) / second heat-sealing resin layer / resin layer / innermost layer ”) was obtained.

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

Subsequently, the 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 a second heat-sealing resin layer was formed after corona treatment (2 kW) was applied to the aluminum oxide vapor-deposited film (third inorganic oxide-deposited layer) of the barrier film 1. The laminated material 3 was obtained.

[Example 4]
The first heat-sealing resin layer was formed on the third inorganic oxide vapor-deposited layer of the barrier film 1, and the second heat-sealing resin layer was formed on the second inorganic oxide-deposited layer. Except for the above, the laminated material 4 (layer structure: "outermost layer / paper base material layer / resin layer / first heat-sealing resin layer / barrier film 1 (third inorganic oxide)" is the same as in Example 1. A vapor-deposited layer / base film / first inorganic oxide vapor-deposited layer / barrier coat layer / second inorganic oxide vapor-deposited layer) / second heat-sealing 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-deposited layer was not formed.

Subsequently, the 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 inorganic oxide-deposited layer and the third inorganic oxide-deposited layer were not formed.

Subsequently, the 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 for forming a second heat-sealing resin layer after corona treatment (2 kW) on the other surface of the PET film of the barrier film 4 (the surface on which the third inorganic oxide vapor deposition layer is not provided). Obtained a laminated material 7 in the same manner as in Comparative Example 2.

[Comparative Example 4]
Except for forming a second heat-sealing resin layer after corona treatment (6 kW) on the other surface of the PET film of the barrier film 4 (the surface on which the third inorganic oxide vapor deposition layer is not provided). Obtained a laminated material 8 in the same manner as in Comparative Example 2.

<Performance evaluation of barrier films and laminated materials>
The following measurements were made on the barrier films and laminated lumbers produced in the above Examples and Comparative Examples.

(Measurement of interlayer adhesion strength)
The laminated intermediate having the first and second heat-sealing resin layers on both sides in the above Examples and Comparative Examples was peeled off using a tensile tester (Tencilon universal tester RTC1310A, manufactured by Orientec). A 90 ° peel test was performed at a speed of 50 mm / min, and the peel strength (N / 15 mm) at the interface between the first heat-sealing resin layer and the barrier film was measured. Similarly, the peel strength (N / 15 mm) at the interface between the barrier film and the second heat-sealing resin layer was measured. The measurement results are shown in Table 2.

(Measurement of oxygen permeability)
The barrier films produced in the above Examples and Comparative Examples were subjected 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 in accordance with this. The measurement results are shown in Table 2.

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

The laminates produced in the above Examples and Comparative Examples were boxed to produce a 200 mL size brick type paper container. For the obtained paper container, attach a sealing tool to connect to a measuring machine (model name: OXTRAN) manufactured by MOCON in the United States in an environment of temperature 23 ° C. and humidity 50% RH, and put it in the paper container. The penetrating oxygen permeability (cc / pkg · day) was measured. The measurement results are shown in Table 2.

10 Barrier film 11 Base film 12 Second inorganic oxide vapor deposition layer 13 First inorganic oxide vapor deposition layer 14 Third inorganic oxide vapor deposition layer 15 Barrier coat layer 20 Laminated material for paper containers 21 Paper base layer 22 Outermost layer 23 Resin layer 24 First heat-sealing resin layer 25 Second heat-sealing resin layer 26 Resin layer 27 Innermost layer

Claims (8)

A stack for a paper container, comprising an outermost layer, a paper base material layer, a first heat-sealing resin layer, a barrier layer, a second heat-sealing resin layer, and an innermost layer in this order. It ’s a material,
The barrier layer includes a second inorganic oxide-deposited layer, a barrier coat layer, a first inorganic oxide-deposited layer, a base film, and a third inorganic oxide-deposited layer in this order. Luba made from the rear film,
The barrier coat layer is a cured film of a hydrolysis product of a metal alkoxide and a water-soluble polymer.
A laminated material for a paper container, wherein the first inorganic oxide-deposited layer is an aluminum oxide-deposited film. The laminated material for a paper container according to claim 1, wherein the aluminum oxide-deposited film of the first inorganic oxide-deposited layer has a film thickness of 5 to 15 nm. The laminate for a paper container according to claim 1 or 2, wherein the second inorganic oxide-deposited layer is an aluminum oxide-deposited film. The laminated material for a paper container according to any one of claims 1 to 3, wherein the third inorganic oxide-deposited layer is an aluminum oxide-deposited film. The paper according to any one of claims 1 to 4, wherein the heat-sealing resin constituting the heat-sealing resin layer is an ethylene-based polymer having a carboxyl group or an acid anhydride group in the molecule. Laminated material for containers. The second inorganic oxide-deposited layer of the barrier film is in contact with the first heat-sealing resin layer.
The laminate for a paper container according to any one of claims 1 to 5, wherein the third inorganic oxide-deposited layer of the barrier film is in contact with the second heat-sealing resin layer. Between the innermost layer and during and / or said second heat-fusible resin layer of the paper substrate layer and the first heat-fusible resin layer, further comprising comprises a resin layer, according to claim 1 The laminated material for a paper container according to any one of 6 to 6. A paper container obtained by manufacturing a laminated material for a paper container according to any one of claims 1 to 7.

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