JP2009220275A - Laminated member for forming liquid paper container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated member for forming a liquid paper container, which is a laminated member used for forming the liquid paper container for storing a liquid substance, showing high barrier property without laminating an aluminum layer or an aluminum foil or the like, and having the gas barrier property which is hardly deteriorated. <P>SOLUTION: In the laminated member, a thermoplastic resin layer is laminated on one side surface of a paper substrate, and a barrier plastic film is laminated on the other side surface, and a sealant layer is laminated on the side of the innermost layer. In the barrier plastic film, a vapor-deposited thin film layer of an aluminum oxide, and a gas barrier coating layer to be a heating and drying coat of a thin film composed of a coating solution where a silicon compound represented by the formulas: Si(OR<SP>1</SP>)<SB>4</SB>and R<SP>2</SP>Si(OR<SP>3</SP>)<SB>3</SB>(where OR<SP>1</SP>and OR<SP>3</SP>are hydrolysable groups and R<SP>2</SP>is an organic functional group) or its hydrolysate, and a water-soluble polymer having a hydroxyl group are mixed through a plasma treatment surface on the plastic film substrate are laminated in this order. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a laminated member for forming a liquid paper container used for forming a liquid paper container for storing a liquid substance such as a beverage, and has a high barrier property without particularly laminating an aluminum layer or an aluminum foil. The present invention relates to a laminated member for forming a liquid paper container in which the gas barrier property is not easily deteriorated.

  In recent years, paper containers and plastic bottles have been widely used in place of cans and bottles as liquid containers for storing beverages such as liquor, juice, and dairy drinks, and liquids such as liquid seasonings, detergents, cosmetics, and shampoos. It is getting to be.

  Under such circumstances, PET bottles are provided with the desired gas barrier properties by various improvements, and are actively used as containers that require gas barrier properties. On the other hand, since the paper container is originally made of a laminated member for forming a container mainly composed of paper having no gas barrier property as a base material, it is difficult to provide the gas barrier property.

  As a laminated member for forming a container constituting a paper container, there is one having a multilayer structure of a paper base material and a plastic layer. The laminated member for container formation having such a structure is generally one having a structure in which a paper base material is sandwiched between layers made of polyethylene, but with such a structure, sufficient gas barrier properties are imparted. Since it is difficult, an aluminum foil or an aluminum vapor deposition layer is laminated to ensure the desired gas barrier properties.

  However, such a container-forming laminated member in which a metal foil or a metal vapor-deposited layer is laminated with a paper base material should be discarded or recycled with the paper base material and the metal foil attached together. However, as an alternative to these, a vapor deposition laminated member in which a vapor deposition thin film layer made of a metal oxide such as aluminum oxide or silica is provided on a paper base material has been used.

  However, these laminated members having a metal oxide vapor-deposited layer on a paper substrate have drawbacks. In other words, the paper-based laminated member having such a configuration is used in various forms as a container-forming member because it has a high gas barrier property and is excellent in discardability. It is unsuitable for use as a component of a liquid container that is forced to be stored in the container. In short, when used in the state described in the description, the gas barrier property deteriorates, the quality of the contents stored in the liquid container deteriorates, and the weight and capacity are reduced due to the transpiration of the contents. End up.

  Among paper-based laminated members having metal oxide vapor-deposited layers, those having a vapor-deposited layer made of aluminum oxide are made of paper for the purpose of containing liquids, in recognition that the vapor-deposited layer of aluminum oxide is vulnerable to water. It is not suitable as a laminated member for forming a container, and a laminated member having a vapor deposition layer of silica is generally used as a laminated member for forming a paper liquid container.

However, there are various problems in the vapor deposition layer made of silica. One of them is a problem of hue exhibited by the deposited layer of silica. If the layer thickness is increased in order to increase the gas barrier property expressed by the silica vapor deposition layer, the hue of the layer will become yellowish brown, but this yellowish brown will deteriorate the appearance of the stored items, so that the packaging material It is a problem that the use as is limited. In order to deal with this, it is conceivable to change the deposition conditions or add an additive to the deposition layer so that it does not turn yellowish brown. However, this will lower the gas barrier properties, and the desired gas barrier will be reduced. It becomes difficult to secure the sex.

  Another problem is a phenomenon called “splash”. That is, when silica is deposited, the silica particles bump up and adhere to the plastic film substrate, which is the substrate to be deposited, as a lump or a small hole is formed, and as a result, the plastic in which the deposited layer of silica is laminated Printing on a laminated member obtained by using a film substrate and securing of gas barrier properties may be hindered.

  On the other hand, the deposited layer of aluminum oxide is colorless and transparent, so that a deposited thin film layer with less so-called splash can be formed, and the above-described problems do not occur.

  Under such circumstances, the inventor has intensively studied, and as a result, a thermoplastic resin layer is laminated on one side of the paper substrate, a barrier plastic film is laminated on the other side, and the innermost layer side. In a laminated member for forming a liquid paper container in which a sealant layer is laminated, even if the barrier plastic film has a vapor-deposited thin film layer made of aluminum oxide having the above-described characteristics, it has a water vapor barrier property. As a result, the present inventors have found that it is possible to provide a gas barrier property and water resistance that are excellent in gas resistance and water resistance, are less susceptible to deterioration, are less susceptible to delamination, and are excellent in environment and disposal. It was.

Under the circumstances as described above, the invention according to claim 1 is characterized in that a thermoplastic resin layer is laminated on one side of the paper substrate, and a barrier plastic film is laminated on the other side. A laminated member for forming a liquid paper container in which a sealant layer is laminated on the inner layer side, wherein the barrier plastic film is a vapor-deposited thin film made of aluminum oxide through a plasma treatment surface on a plastic film substrate A silicon compound represented by a layer, Si (OR ¹ ) ₄ and R ² Si (OR ³ ) ₃ (OR ¹ and OR ³ are hydrolyzable groups, R ² is an organic functional group) or a hydrolyzate thereof, A gas barrier coating layer, which is a heat-dried thin film made of a coating solution mixed with a water-soluble polymer having a hydroxyl group, is at least laminated in this order. That a laminated member for a liquid cartons formed.

The invention described in claim 2 is the invention described in claim 1, wherein the Si (OR ¹ ) ₄ and R ² Si (OR ³ ) ₃ (OR ¹ and OR ³ are hydrolyzable groups, and R ² is The organic functional group (R ² ) of the silicon compound represented by (organic functional group) or a hydrolyzate thereof has a non-aqueous functional group of any one of vinyl, epoxy, methacryloxy, ureido, and isocyanate.

Furthermore, the invention of claim 3 is the invention of claim 1, wherein the Si (OR ¹ ) ₄ and R ² Si (OR ³ ) ₃ (OR ¹ , OR ³ are hydrolyzable groups, R ² Is characterized in that the silicon functional group (R ² ) of the silicon compound or its hydrolyzate is an isocyanurate in which an isocyanate group is polymerized.

  The laminated member for forming a liquid paper container of the present invention is particularly excellent in gas barrier properties and water resistance, and the properties thereof are not easily deteriorated. Even if the liquid is stored across, it will be possible to prevent the deterioration of the gas barrier properties and water resistance originally possessed, the quality deterioration of the contents stored in the liquid paper container, It is possible to suppress the weight and capacity loss accompanying the transpiration of the contents, and it is expected to have many practical effects.

  Hereinafter, the present invention will be described in detail with reference to the drawings. 1 and 2 respectively show schematic cross-sectional configurations of the liquid paper container forming laminated member of the present invention.

  FIG. 3 is an explanatory diagram showing a schematic configuration of a liquid paper container produced using the laminated member for forming a liquid paper container of the present invention.

In the laminated member for forming a liquid paper container shown in FIG. 1, the thermoplastic resin layer (1) is laminated on one side of the paper substrate (2), and the barrier plastic film (3) is laminated on the other side, Further, a sealant layer (4) is laminated on the innermost side. The barrier plastic film (3) comprises a vapor-deposited thin film layer (7) made of aluminum oxide, Si (OR ¹ ) ₄ and R ² Si (OR) through a plasma treated surface on the plastic film substrate (6). ³ ) Coating solution in which a silicon compound represented by ₃ (OR ¹ and OR ³ are hydrolyzable groups, R ² is an organic functional group) or a hydrolyzate thereof, and a water-soluble polymer having a hydroxyl group are mixed. A gas barrier coating layer (8), which is a heat-dried coating of a thin film made of, is at least laminated in this order.

  The laminated member for forming a liquid paper container shown in FIG. 2 is substantially the same as that shown in FIG. 1, but comprises a plastic film substrate (6) constituting the barrier plastic film (3) and aluminum oxide. The difference is that the deposition order of the vapor-deposited thin film layer (7) and the gas barrier coating layer (8) is different.

  Examples of the thermoplastic resin constituting the thermoplastic resin layer (1) laminated on one surface of the paper substrate (2) include linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), High density polyethylene (HDPE), polypropylene (PP), polyethylene terephthalate (PET), polyester such as polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyamide such as nylon-6 and nylon-66, polyimide, etc. Or a high molecular weight copolymer is used.

  The thickness of the thermoplastic resin layer (1) composed of such a thermoplastic resin is not particularly limited, but consideration is given to protection of the paper base (2) and workability when laminating other layers described later. It is preferable that the thickness is about 10 to 30 μm.

The type of the paper substrate (2) is not particularly limited, and varies depending on the shape and capacity of the liquid paper container to be produced with the liquid paper container forming laminate of the present invention. What is necessary is just to select suitably from what can hold | maintain the moldability of this, shape retention property, intensity | strength, etc. Specifically, a paperboard having a basis weight of about 200 to 500 g / m ² can be used.

  As shown in the figure, a printing layer (5) is generally formed on the paper substrate (2). This printed layer (5) is provided so that the laminate for forming a liquid paper container according to the present invention can be used practically as a packaging material for forming a liquid paper container. It is a layer composed of ink in which various pigments, extender pigments, plasticizers, desiccants, stabilizers, etc. are added to the conventionally used ink binder resins such as cellulose, rubber, etc. This is the part that displays symbols, numbers, symbols, etc. For the formation of the printing layer (5), for example, a printing method such as an offset printing method, a gravure printing method, a silk screen printing method, or a coating method such as a roll coating, a knife edge coating, or a gravure coating can be used. The thickness is usually about 0.1 to 2.0 μm.

The method for laminating the thermoplastic resin layer (1) and the paper substrate (2) is not particularly limited, and for example, a known laminating method can be used.

  On the other hand, the barrier plastic film (3) is formed by laminating at least a plastic film substrate (6), a vapor-deposited thin film layer (7) made of aluminum oxide, and a gas barrier coating layer (8) in this order. (See FIGS. 1 and 2).

  The plastic film substrate (6) is, for example, a polyester film made of polyethylene terephthalate (PET) or polyethylene naphthalate, a polyolefin film made of polyethylene or polypropylene, a polystyrene film, a polyamide film, a polyvinyl chloride film, a polycarbonate film, a poly It consists of biodegradable plastic films such as acrylonitrile film, polyimide film and polylactic acid film. These film substrates may be stretched or unstretched, but those having excellent mechanical strength and dimensional stability are preferred. In these, the film base material which consists of a polyethylene terephthalate arbitrarily extended | stretched to biaxial direction especially from surfaces, such as heat resistance, is used preferably.

  The thickness of the plastic film substrate (6) is about 1 μm or more, suitability as a packaging material, laminating other layers, a vapor deposition thin film layer (7) made of aluminum oxide, and a gas barrier coating layer ( In consideration of the workability in the case of sequentially laminating 8), it is practically preferable to set the range of about 3 to 200 μm and about 6 to 30 μm depending on the application.

  In consideration of mass productivity, it is desirable to use a long film so that the above-described layers can be formed continuously.

  In general, a polyester film is often used as a plastic film substrate for packaging materials. When a polyester film is used as a plastic film substrate (6), for example, terephthalic acid is used as a dicarboxylic acid component constituting the polyester film. , Aromatic dicarboxylic acids such as naphthalenecarboxylic acid, isophthalic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfoisophthalic acid, phthalic acid, and alicyclic dicarboxylic acids such as cyclohexynedicarboxylic acid Oxalic acid, oxalic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, p-oxybenzoic acid and other oxycarboxylic acids. Examples of alcohol components include aliphatic glycols such as ethylene glycol, propanediol, 1,4 butanediol, 1,6 hexanediol, and neopentyl glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, and 1,4 cyclohexane. Examples thereof include polyoxyalkylene glycols such as dimethanol, aromatic glycols such as bisphenol A and bisphenol S, and derivatives thereof.

  Among these polyesters, those mainly composed of polyethylene terephthalate or polyethylene naphthalate are preferably used in consideration of film forming properties such as biaxial stretching properties, humidity properties, heat resistance, and chemical resistance. In addition, within the range where various physical properties of polyethylene terephthalate can be maintained, other alcohol components are controlled so as to be incorporated into the main chain at the polymerization stage, and copolymerization is performed, so that a segment with a small rotational hindrance in the molecular chain (soft segment) ), And a force generated by external impact or bending is absorbed by the soft segment in the molecular chain, so that it has excellent impact resistance and flexibility. It is also preferred to use a copolymer polyester in which 50 mol% or more of each of the carboxylic acid component and the alcohol component is terephthalic acid, ethylene glycol, and derivatives thereof.

In order to improve the adhesion between the plastic film substrate (6) and the transparent deposited thin film layer (7) made of aluminum oxide, the surface of the plastic film substrate (6) is subjected to plasma treatment. By applying this treatment, the surface of the plastic film substrate (6) can be provided with a functional group using radicals and ions generated during the treatment, and the surface is ion-etched to scatter impurities. Smoothing. Therefore, a dense thin film of aluminum oxide can be formed on the plasma treated surface. As a result, the adhesion between the plastic film substrate (6) and the vapor deposited thin film layer (7) made of aluminum oxide can be further strengthened, the gas barrier property and moisture resistance can be improved, and cracks in the vapor deposited thin film layer (7) can be obtained. Can be prevented.

  Although there is no limitation on this plasma processing method, a method of performing processing in-line with a plasma processing device using a winding type vapor deposition apparatus is effective.

  As a method of forming the vapor deposition thin film layer (7) made of aluminum oxide, a normal vacuum vapor deposition method, a sputtering method, an ion plating method, a plasma vapor deposition method (CVD), or the like, which is another thin film formation method, is used. be able to. However, considering productivity, the vacuum deposition method is the best at present. An electron beam heating method, a resistance heating method, an induction heating method, or the like is preferably used as a heating means when forming a thin film using a vacuum evaporation apparatus by a vacuum evaporation method. In order to improve the adhesion between the deposited thin film and the plastic film substrate (6) and the denseness of the thin film, a plasma assist method or an ion beam assist method can be used.

  More specifically, when vapor-depositing aluminum with heat and vapor-depositing it on the plastic film substrate (6), oxygen gas is introduced to form a vapor-deposited thin film layer (7) made of aluminum oxide. The amount of oxygen gas introduced at this time is related to the improvement of the water vapor barrier property and the degree of transparency of the thin film, and the appropriate amount of introduction varies depending on the exhaust capacity of the vapor deposition apparatus to be used. The amount may be appropriately determined according to the degree.

  The thickness of the vapor-deposited thin film layer (7) made of aluminum oxide varies depending on the use and configuration of the liquid paper container produced by the laminated member for forming a liquid paper container of the present invention. It is desirable to be in the range of about 300 nm. If the thickness is less than 5 nm, it is difficult to obtain a uniform film, the film thickness may be insufficient, and the function as a gas barrier material may not be sufficiently achieved. When the film thickness exceeds 300 nm, it is difficult to maintain flexibility in the thin film, and there is a possibility that the thin film may be cracked by applying a force such as bending and pulling from the outside after film formation. Preferably, it may be in the range of about 5 to 100 nm.

  The gas barrier coating layer (8) laminated on the vapor-deposited thin film layer (7) made of aluminum oxide thus provided imparts higher gas barrier properties to the laminated member for forming a liquid paper container of the present invention. In order to do so, and to physically protect the deposited thin film layer (7), it is provided.

In order to achieve such an object, the gas barrier coating layer (8) is composed of Si (OR ¹ ) ₄ and R ² Si (OR ³ ) ₃ (R ¹ and R ³ are CH ₃ , C ₂ H ₅ , C _A thin film comprising a coating solution in which a hydrolyzable group such as ₂ H ₄ OCH ₃ , R ² is an organic functional group) or a hydrolyzate thereof, and a water-soluble polymer having a hydroxyl group are mixed. It is necessary to be a gas barrier coating that is a heat-dried coating. Hereinafter, each component contained in the coating liquid will be described.

R ² Si (OR ³ ) ₃ is R ³ is a hydrolyzable group such as CH ₃ , C ₂ H ₅ , C ₂ H ₄ OCH ₃ , R ² is an organic functional group invention, and is generally a silane cup It is used as a ring agent to improve the adhesion between the organic layer and the inorganic layer. In the present invention, it is necessary for improving the adhesion between the vapor-deposited thin film layer (7) made of aluminum oxide and the gas barrier coating layer (8). Among them, organic functional groups (R ² ) having non-aqueous functional groups such as vinyl groups, epoxy groups, ureido machines, and isocyanate groups are non-aqueous and have high resistance to hot water, and the isocyanate groups are polymerized. Isocyanurate is particularly preferred because it is easy to handle in the coating solution, slows the gelation of the coating solution, and can improve adhesion without causing a decrease in barrier properties due to the addition of a silane coupling agent. .

  The hydrolyzable group described above represents a group that can be converted to a hydroxyl group by reacting with water under acidic, basic or neutral conditions. For example, an alkoxy group, an aryloxy group, a halogen atom , Acetoxy group, isocyanate group, hydroxyl group and the like. Among these, an alkoxy group is preferable from the viewpoint of the stability of the coating solution. Of these, lower alkoxy groups having 1 to 5 carbon atoms are preferable, but these alkoxy groups may be chain-like or branched, and a hydrogen atom may be substituted with a fluorine atom or the like. Also preferred are methoxy and ethoxy groups.

  In addition, the isocyanurate is a product obtained by polymerizing three isocyanate groups to form a ring, and more preferably one obtained by polymerizing three isocyanate group-containing silanes in a ring.

  On the other hand, the water-soluble polymer having a hydroxyl group refers to polyvinyl alcohol, starch, celluloses and the like. In particular, when polyvinyl alcohol (hereinafter referred to as PVA) is used as one component of the coating solution described above, the gas barrier property is most excellent. PVA as used herein is generally obtained by saponifying polyvinyl acetate, and saponification is complete saponification in which only several percent of acetic acid groups remain from so-called partially saponified PVA in which several tens of percent of acetic acid groups remain. Includes up to PVA.

The method for mixing the coating solution constituting the gas barrier coating layer is not particularly limited, but it is preferable to carry out in consideration of the manifestation of the barrier effect, fine dispersion of SiO ₂ and the hydrolysis efficiency of Si (OR ¹ ) ₄ .

  In addition, to improve the adhesion and wettability of inks and adhesives to the coating solution, and to prevent cracks due to shrinkage, isocyanate compounds, clay minerals such as colloidal silica and smectite, stabilizers, coloring Known additives such as agents and viscosity modifiers can be added as long as gas barrier properties and water resistance are not impaired.

  As a method for forming a thin film comprising a coating solution, a normal coating method can be used. For example, dipping method, roll coating method, gravure coating method, reverse coating method, air knife coating method, comma coating method, die coating method, screen printing method, spray coating method, gravure offset method and the like. What is necessary is just to apply | coat a thin film on a vapor deposition thin film using these coating systems.

  As a method for drying a thin film made of a coating solution, heat is applied to the thin film made of a coating solution, such as hot air drying, hot roll drying, high-frequency irradiation drying, infrared irradiation drying, and UV irradiation drying, and water molecules are skipped to dry. The method is applied. Also, two or more methods described above may be combined.

When the heat applied to the thin film made of the coating solution is about 200 ° C. or higher, the barrier property is further improved, and the moisture resistance and water resistance are also improved. By performing a heat drying treatment at about 200 ° C. or higher, high barrier properties and adhesion can be maintained without deterioration of the gas barrier coating layer even when exposed to a liquid content or a high temperature storage environment. This is because the hydrolysis of the hydrolyzed metal alkoxide contained in the thin film made of the coating solution proceeds and the water-soluble polymer is sufficiently dehydrated by the high temperature treatment.

  As described above, a general hot air drying method or a hot roll drying method can be used as a method of heat drying treatment at a high temperature of about 200 ° C. or higher. The same effect can be obtained by a flame treatment method in which heat treatment is performed with a flame. In addition, a stretch coating method in which a coating solution is applied at the time of film stretching is also effective if the heat setting temperature of the stretched film is 200 ° C. or higher.

  The thickness of the thin film made of the coating solution after heating and drying is not particularly limited. However, if the thickness exceeds 50 μm, cracks are likely to occur. Therefore, the thickness should be about 0.01 to 50 μm. desirable.

  The barrier plastic film (3), the paper base (2) and the thermoplastic resin layer (1) thus obtained have the barrier properties of the thermoplastic resin layer (1) and the paper base (2). The plastic film (3) is laminated so as to be positioned on both sides thereof.

  As a laminating method at this time, for example, a known laminating method is used. The order of lamination is not particularly limited, but the method of laminating the thermoplastic resin layer (1) and the paper substrate (2) and then laminating the barrier plastic film (3) is the barrier plastic film (3). This is preferable because of less stress (heating and tension).

  The surface of the barrier plastic film (3) in contact with the paper substrate (2) may be either.

  As shown in FIGS. 1 and 2, the laminated member for forming a liquid paper container of the present invention has a thermoplastic resin layer (1) on one side of the paper substrate (2) and a barrier property on the other side. A plastic film (3) is laminated, and a sealant layer (4) is laminated on the innermost side.

  This sealant layer (4) is a layer that is laminated so as to serve as an adhesive layer to form a paper container, and may be any layer that can be melted by heat and fused to each other, and its constituent materials are limited. Not what you want. Specifically, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid Copolymers, ethylene-methacrylic acid copolymers, ethylene-propylene copolymers, methylpentene polymers, polyolefin resins such as polyethylene or polypropylene, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid Resins such as acid-modified polyolefin resins modified with unsaturated carboxylic acids such as can be used. The thickness is appropriately determined depending on the application, but is preferably about 15 to 70 μm.

  Further, the sealant layer (4) may be formed of a low adsorptive sealant material for the purpose of suppressing / preventing adsorption of medicinal components such as limonene and perfume components. As the low adsorptive sealant material, a polyester sealant material or an ethylene-vinyl alcohol (EVOH) copolymer resin sealant material is suitable.

  The polyester resin constituting the polyester sealant material is a polyester resin obtained by copolymerization of a dicarboxylic acid component mainly composed of terephthalic acid, a glycol component mainly composed of ethylene glycol, and a tri- or higher functional polycarboxylic acid and / or polyol. And a polyester resin composition containing a polyester resin having a melting point lower than that of the polyester resin and having a branched chain.

  The polyester resin is composed of an aromatic dicarboxylic acid mainly composed of terephthalic acid and a glycol component mainly composed of ethylene glycol, and contains a polycarboxylic acid or a polyol having three or more functional groups for the total acid component or the total glycol component. A polyester resin mixture obtained by mixing a polyester resin having a branched chain, an aromatic dicarboxylic acid mainly composed of terephthalic acid, and a polyester resin not composed of a glycol component mainly composed of ethylene glycol. A polyester resin composition containing a coalescence is also included.

  The liquid paper container produced by using the laminated member for forming the liquid paper container of the present invention having the above-described configuration includes a gobeltop type (roof type) liquid paper container as shown in FIG. There are (brick type) liquid paper containers and the like, but are not necessarily limited thereto.

  Examples of the present invention will be specifically described below.

First, the component solutions A to F of the coating solution constituting the gas barrier coating layer were prepared. (Component solution A)
A hydrolyzed solution obtained by adding 70 g of hydrochloric acid (0.1N) to 20 g of tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ; hereinafter referred to as TEOS) and 10 g of methanol and stirring the mixture for 30 minutes for hydrolysis.
(Component solution B)
5% of polyvinyl alcohol, water / methanol = 95/5 aqueous solution.
(Component solution C)
Hydrolysis solution prepared by adjusting 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate with water / IPA = 1/1 solution.
(Component solution D)
Hydrochloric acid (1N) is gradually added to a solution of β- (3,4 epoxycyclohexyl) trimethoxysilane and isopropyl alcohol (IPA), stirred for 30 minutes, hydrolyzed, and then added with water / IPA = 1/1 solution. Hydrolysis solution prepared by decomposing.
(Component solution E)
Hydrolysis prepared by gradually adding hydrochloric acid (1N) to γ-glycidoxypropyltrimethoxysilane and IPA solution, stirring for 30 minutes, hydrolyzing, and then hydrolyzing with water / IPA = 1/1 solution solution.
(Component solution F)
Hydrolysis solution prepared by gradually adding hydrochloric acid (1N) to vinyltrimethoxysilane and IPA solution, stirring for 30 minutes, hydrolyzing, and then hydrolyzing with water / IPA = 1/1 solution.

Next, using the component solutions prepared as described above, coating solutions 1 to 4 for forming a gas barrier film layer were prepared.
(Coating solution 1)
The component solutions A, B, and C were mixed at a ratio of A / B / C = 70/20/10 (wt%) to obtain a coating solution 1 for forming a gas barrier coating layer.

(Coating solution 2)
The component solutions A, B, and D were mixed at a ratio of A / B / D = 70/20/10 (wt%) to obtain a coating solution 2 for forming a gas barrier coating layer.
(Coating solution 3)
Component solutions A, B, and E were mixed at a ratio of A / B / E = 70/20/10 (wt%) to obtain a coating solution 3 for forming a gas barrier coating layer.
(Coating solution 4)
Component solutions A, B, and F were mixed at a ratio of A / B / F = 70/20/10 (wt%) to obtain a coating solution 4 for forming a gas barrier coating layer.

Subsequently, a paperboard having a basis weight of 300 g / m ² was used as a paper substrate, and a thermoplastic resin layer having a thickness of 20 μm and made of low density polyethylene (LDPE) was laminated on one surface thereof by a hot melt extrusion coating method.

  On the other hand, a plasma pretreatment is performed on one side of a 12 μm-thick biaxially stretched polyethylene terephthalate (PET) film using a plasma treatment device, and then a vacuum deposition apparatus using an electron beam heating method on the plasma treatment surface in-line. Then, a deposited thin film layer made of aluminum oxide and having a thickness of 15 nm was laminated to obtain a deposited film. At this time, a high frequency power source was used for the electrodes, and vapor deposition was performed while introducing oxygen gas in an argon / oxygen mixed gas atmosphere.

  And on the vapor deposition thin film layer of the vapor deposition film obtained at the said process, a thin film is formed with each of the above-mentioned coating solutions 1-4 by the gravure coating method, and it is heat-dried at 120 degreeC for 2 minutes after that, and thickness is A 0.5 μm gas barrier coating layer was formed to obtain barrier plastic films a to d.

  Further, a barrier plastic film e was obtained by the same method as that for producing the barrier plastic film a except that the plasma treatment was not performed on one surface of the biaxially stretched polyethylene terephthalate film.

  Further, a barrier plastic film f was obtained by the same method as that for producing the barrier plastic film a except that the gas barrier coating layer was not provided.

  Further, a barrier plastic film g was obtained by the same method as that for producing the barrier plastic film a except that an aluminum foil having a thickness of 7 μm was used instead of the deposited thin film layer made of aluminum oxide. .

  The barrier plastic films a to g obtained as described above were formed on the surface of the paper base material on which the thermoplastic resin layer obtained by the above process was laminated without forming the thermoplastic resin layer. Lamination was performed by melt extrusion laminating so that the material was positioned.

  Then, a sealant layer (thickness 20 μm) made of low density polyethylene (LDPE) is laminated on the gas barrier coating layers of the laminated barrier plastic films a to g by a hot melt extrusion laminating method. Laminate material A for liquid paper container according to example 1 (use of barrier plastic film a), Laminate material B for liquid paper container according to example 2 (use of barrier plastic film b), for liquid paper container according to example 3 Laminated material C (using barrier plastic film c), laminated material D for liquid paper container according to Example 4 (using barrier plastic film d), and laminated material for liquid paper container according to Example 5 for comparison E (use of barrier plastic film e), laminate material F for liquid paper container according to Example 6 (barrier plastic film f) Use) were obtained, respectively.

Next, the above-described barrier plastic films a to g and laminated materials A to G were evaluated as follows.
<Evaluation 1>
The oxygen permeability (cm ³ / m ² · day · atm) and the water vapor permeability (g / m ² · day) of the barrier plastic films a to g were measured. The measurement results are shown in Table 1.
<Evaluation 2>
A four-sided pouch having a side of 10 cm was made using the laminate materials A to G according to each example, and about 20 g of tap water was filled therein as the contents. This pouch is stored in an environment of 40 ° C.-20% RH and 60 ° C.-Free for 6 months, and the weight change rate of the tap water converted into the period is obtained, and the quality of each laminated member {(less change rate) ◎, × (Large change rate)} was determined and the suitability of the contents was evaluated. The determination results are shown in Table 1.
<Evaluation 3>
The suitability of the processability of the laminated materials A to G according to each example {(easy to process) ◎>○> △ (difficult to process)} was determined. The determination results are shown in Table 1.
<Evaluation 4>
The quality of the environmental suitability {(appropriate) ◎, x (unsuitable)} of the laminated materials A to G according to each example was determined. The determination results are shown in Table 1.
<Evaluation 5>
A gobel top type (roof type) container was formed using the laminated materials A to G according to each Example, and after filling it with orange fruit juice sterilized by heating, it was left in the room for one month. At this time, sensory evaluation was performed on the change in flavor of the orange juice immediately after filling and after standing, and the quality {(small change) ◎>○> × (high change)} was determined. The determination results are shown in Table 1.

As is clear from the table, the laminated members for forming liquid paper containers according to Examples 1 to 4 of the present invention can suppress weight loss over time related to water storage while having high gas barrier properties. Moreover, it also has environmental suitability and content suitability.

It is explanatory drawing which shows the general | schematic cross-section structure of the lamination member for liquid paper container formation of this invention. It is explanatory drawing which shows the general | schematic cross-section structure of the lamination member for other liquid paper container formation of this invention. It is explanatory drawing which shows the liquid paper container produced using the lamination member for other liquid paper container formation of this invention.

Explanation of symbols

(1) Thermoplastic resin layer (2) Paper substrate (3) Barrier plastic film (4) Sealant layer (5) Print layer (6) Plastic film substrate (7) Vapor deposition thin film layer (8) made of aluminum oxide Gas barrier coating layer

Claims (3)

Laminate for forming a liquid paper container in which a thermoplastic resin layer is laminated on one side of the paper substrate, a barrier plastic film is laminated on the other side, and a sealant layer is laminated on the innermost side. The barrier plastic film includes a vapor-deposited thin film layer made of aluminum oxide, Si (OR ¹ ) ₄ and R ² Si (OR ³ ) ₃ (OR ¹ , OR ³ is a hydrolyzable group, R ² is an organic functional group) and heating a thin film comprising a coating solution in which a hydrolyzate thereof and a water-soluble polymer having a hydroxyl group are mixed A laminated member for forming a liquid paper container, characterized in that a gas barrier coating layer, which is a dry coating, is laminated at least in this order. An organic functional group of the silicon compound or its hydrolyzate represented by the Si (OR ¹ ) ₄ and R ² Si (OR ³ ) ₃ (OR ¹ and OR ³ are hydrolyzable groups, R ² is an organic functional group) ^{2. The} laminated member for forming a liquid paper container according to claim 1, wherein (R ² ) has a non-aqueous functional group of any one of vinyl, epoxy, methacryloxy, ureido, and isocyanate. An organic functional group of the silicon compound or its hydrolyzate represented by the Si (OR ¹ ) ₄ and R ² Si (OR ³ ) ₃ (OR ¹ and OR ³ are hydrolyzable groups, R ² is an organic functional group) ^{2. The} laminated member for forming a liquid paper container according to claim 1, wherein (R2) is an isocyanurate in which an isocyanate group is polymerized.