JP7425984B2 - Packaging materials for paper containers and liquid paper containers - Google Patents

Description

The present invention relates to a liquid paper container containing a liquid and a packaging material for constructing the liquid paper container.

Polyester has excellent mechanical properties, chemical stability, heat resistance, transparency, etc., and is inexpensive, so it is widely used in various industrial applications. Polyester is obtained by polycondensing diol units and dicarboxylic acid units. For example, polyethylene terephthalate (hereinafter sometimes abbreviated as PET) is obtained by esterifying ethylene glycol and terephthalic acid as raw materials. After that, it is produced by polycondensation reaction. These raw materials are produced from petroleum, which is a fossil resource; for example, ethylene glycol is industrially produced from ethylene, and terephthalic acid is industrially produced from xylene.

In recent years, with increasing calls for building a recycling-oriented society, there is a desire to move away from fossil fuels in the materials field as well as energy, and the use of biomass is attracting attention. Biomass is an organic compound that is photosynthesized from carbon dioxide and water, and by using it, it becomes carbon dioxide and water again, so it is a so-called carbon-neutral renewable energy. In recent years, the practical use of biomass plastics made from these biomass raw materials has progressed rapidly, and attempts are also being made to produce polyester, which is a general-purpose polymer material, from these biomass raw materials.

Polyesters made from isosorbide, which is one of the biomass raw materials, terephthalic acid, and ethylene glycol are known as polyesters using biomass raw materials. For example, Patent Document 1 proposes constructing a liquid paper container for storing liquid using a packaging material containing biomass polyester (hereinafter simply "biomass polyester") made from biomass-derived ethylene glycol. The packaging material of Patent Document 1 includes a base material layer mainly composed of polyester consisting of a diol unit containing biomass-derived ethylene glycol and a dicarboxylic acid unit, a paper base layer adhered to the base material layer, A transparent vapor deposition layer made of aluminum oxide is formed on the base material layer by physical vapor deposition.

JP2015-36208A

Aluminum oxide has lower heat resistance than inorganic compounds such as silicon oxide, which are examples of other materials constituting the transparent vapor deposition layer. Therefore, the barrier deterioration of the transparent vapor deposited layer containing aluminum oxide may be caused due to the heat generated when adhering the vapor deposited film having the transparent vapor deposited layer containing aluminum oxide to the paper base layer.

An object of the present invention is to provide a packaging material for paper containers that can effectively solve such problems.

The present invention is a packaging material for a paper container, which includes, in order from the outside to the inside, at least an outer thermoplastic resin layer, a paper base layer, an adhesive resin layer, a vapor-deposited film, an adhesive layer, and an inner thermoplastic resin layer. The vapor-deposited film includes a stretched plastic film, a transparent vapor-deposited layer containing aluminum oxide and provided on the inner surface of the stretched plastic film, and a gas barrier coating film provided on the transparent vapor-deposited layer. and, the stretched plastic film of the vapor-deposited film is a packaging material for a paper container containing biomass-derived polyester.

In the packaging material for paper containers according to the present invention, the gas barrier coating film of the vapor-deposited film may be in contact with the adhesive layer.

In the packaging material for paper containers according to the present invention, the adhesive resin layer is made of one or two selected from the group consisting of an epoxy group-containing compound, a silane group-containing compound, a carboxylic acid group-containing compound, and an acid anhydride-containing compound. A resin composition containing the above compounds may be used.

In the packaging material for paper containers according to the present invention, the adhesive resin layer may be in contact with the outer surface of the stretched plastic film.

In the packaging material for paper containers according to the present invention, the thickness of the adhesive resin layer may be 15 μm or more and 40 μm or less.

In the packaging material for paper containers according to the present invention, the transparent vapor deposition layer includes a transition region, and the transition region allows the vapor deposition film to be measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS) from the gas barrier coating film side. ) in the region between the peak position of the elemental bond Al ₂ O ₄ H that transforms into aluminum hydroxide and the interface between the transparent vapor deposited layer and the stretched plastic film. The ratio of the thickness of the transition region to the thickness of the transparent vapor deposition layer may be 5% or more and 60% or less.

In the packaging material for paper containers according to the present invention, the outer thermoplastic resin layer or the inner thermoplastic resin layer may contain biomass-derived polyethylene.

The present invention is a liquid paper container made of the paper container packaging material described above.

According to the present invention, it is possible to suppress deterioration of the characteristics of a transparent vapor deposited layer containing aluminum oxide due to heat.

FIG. 1 is a cross-sectional view showing an example of a packaging material according to the present embodiment. FIG. 2 is a cross-sectional view showing an example of a vapor-deposited film of the packaging material according to the present embodiment. It is a figure which shows an example of the result of analyzing a transparent vapor deposition layer with a time-of-flight type secondary ion mass spectrometer. FIG. 2 is a diagram showing an example of a film forming apparatus for forming a transparent vapor deposition layer on a stretched plastic film. FIG. 2 is a cross-sectional view showing an example of a laminate obtained by laminating a vapor-deposited film and an inner thermoplastic resin layer. FIG. 2 is a diagram showing an example of a lamination apparatus for laminating a paper base layer and a laminate having a vapor-deposited film and an inner thermoplastic resin layer. FIG. 2 is a perspective view showing an example of a liquid paper container. FIG. 3 is a diagram showing the evaluation results of Examples A1 to A3. FIG. 3 is a diagram showing the evaluation results of Reference Examples A1 to A5. FIG. 3 is a diagram showing the layer structure of packaging materials for paper containers of Examples B1 to B4 and Comparative Examples B1 to B4. It is a figure showing the measurement results of peel strength, water vapor permeability, and oxygen permeability. It is a figure which shows the evaluation result of filling machine sealing property.

In the present invention, "biomass polyester" and "stretched plastic film containing biomass polyester" are those that use biomass-derived raw materials at least in part as raw materials, and all of the raw materials are biomass-derived. does not mean.

<Packaging materials>
The packaging material 10 for paper containers according to the present embodiment will be described with reference to the drawings. FIG. 1 shows an example of a schematic cross-sectional view of the packaging material 10 for paper containers according to the present embodiment.

The paper container packaging material 10 shown in FIG. 1 includes, in order from the outside to the inside, at least an outer thermoplastic resin layer 11, a paper base layer 12, an adhesive resin layer 13, a vapor deposited film 14, an adhesive layer 15, and An inner thermoplastic resin layer 16 is provided. In the liquid paper container including the paper container packaging material 10 shown in FIG. 1, the inner thermoplastic resin layer 16 constitutes the inner surface (hereinafter also referred to as the inner surface) 10x of the liquid paper container. Further, the outer thermoplastic resin layer 11 constitutes an outer surface (hereinafter also referred to as outer surface) 10y of the liquid paper container. "Inside" refers to the side located closer to the inside of the liquid paper container when the paper container packaging material 10 constitutes a liquid paper container, and "outer" refers to the side located closer to the outside of the liquid paper container. It's on the side.

The paper container packaging material 10 may further include a printed layer or the like in addition to the above-mentioned layers. For example, the outer thermoplastic resin layer 11 may be provided with a printed layer.

The films and layers constituting the paper container packaging material 10 will be described below.

[Thermoplastic resin layer]
The outer thermoplastic resin layer 11 and the inner thermoplastic resin layer 16 can be formed using thermoplastic resins that can be melted and fused together by heat. Thermoplastic resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymer polymerized using a metallocene catalyst, polypropylene, and 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 resins made by modifying polyolefin resins such as methylpentene polymers, polybutene polymers, polyethylene or polypropylene with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid, and polyacetic acid. Examples include resins such as vinyl resins, poly(meth)acrylic resins, and polyvinyl chloride resins. Preferably, low density polyethylene, linear low density polyethylene, or ethylene-α/olefin copolymer polymerized using a metallocene catalyst is used.

The thermoplastic resin of the outer thermoplastic resin layer 11 and the inner thermoplastic resin layer 16 may contain a biomass-derived material or a fossil fuel-derived material. When the thermoplastic resin layer contains a material derived from biomass, it may contain biomass polyolefin, which is a polymer of monomers containing ethylene derived from biomass. Since biomass-derived ethylene is used as the raw material monomer, the polymerized polyolefin is biomass-derived. The content of biomass-derived ethylene in the raw material monomer does not need to be 100% by mass, and is, for example, preferably 50% or more, more preferably 80% or more. The raw material monomer may include ethylene derived from fossil fuels, and may include monomers of α-olefins such as butylene, hexene, and octene. Even in such a case, the obtained polymer is called biomass polyethylene. By including an α-olefin, the polymerized polyolefin has an alkyl group in a branched structure, so it can be made more flexible than a simple linear one.

Biomass-derived ethylene can be produced using biomass-derived ethanol as a raw material. In particular, it is preferable to use fermented ethanol derived from biomass obtained from plant materials. The plant raw material is not particularly limited, and conventionally known plants can be used. For example, corn, sugar cane, beets and manioc may be mentioned.

Fermented ethanol derived from biomass refers to ethanol produced by contacting a culture solution containing a carbon source obtained from a plant material with a product derived from an ethanol-producing microorganism or its crushed product, and then purified. Conventionally known methods such as distillation, membrane separation, and extraction can be applied to purify ethanol from the culture solution. For example, methods include adding benzene, cyclohexane, etc. and azeotropically distilling the mixture, or removing water by membrane separation or the like.

Linear low-density polyethylene is obtained by polymerizing ethylene and a small amount of α-olefin using a low-pressure polymerization method (gas phase polymerization method using a Ziegler-Natta catalyst or liquid phase polymerization method using a metallocene catalyst). . Furthermore, low-density polyethylene is obtained by polymerizing ethylene using a high-pressure polymerization method. Linear low-density polyethylene has many short molecular chains in its molecular chains and has excellent sealing performance.

The linear low density polyethylene and low density polyethylene have a density of 0.89 g/cm ³ or more and 0.93 g/cm ³ or less, more preferably 0.90 g/cm ³ or more and 0.925 g/cm ³ or less. be. Note that the MFR of linear low-density polyethylene may be lower than that of low-density polyethylene. The density of linear low density polyethylene and low density polyethylene is a value measured according to the method specified in Method A of JIS K7112-1980 after performing annealing as described in JIS K6760-1995. If the density of the linear low-density polyethylene and the low-density polyethylene is less than 0.89 g/cm ³ , the slipperiness of the thermoplastic resin layers 11 and 16 will decrease. Moreover, when the density of linear low density polyethylene and low density polyethylene exceeds 0.93 g/cm ³ , the sealing properties of the thermoplastic resin layers 11 and 16 deteriorate.

Linear low density polyethylene and low density polyethylene are 0.1 g/10 minutes or more and 10 g/10 minutes or less, preferably 0.2 g/10 minutes or more and 9 g/10 minutes or less, more preferably 1 g/10 minutes or more8. It has a melt flow rate (MFR) of 5 g/10 minutes or less. Note that the MFR of linear low-density polyethylene may be lower than that of low-density polyethylene. The melt flow rate is a value measured by method A under conditions of a temperature of 190° C. and a load of 21.18 N in the method specified in JIS K7210-1995. When the MFR of linear low density polyethylene and low density polyethylene is less than 0.1 g/10 minutes, extrusion load is applied during molding. Furthermore, when the MFR of the linear low density polyethylene and the low density polyethylene exceeds 10 g/10 minutes, the resin flows too much, resulting in a sealing problem, which is not preferable.

As the biomass polyethylene, biomass-derived linear low-density polyethylene manufactured by Braskem (trade name: SLL118, density: 0.916 g/cm ³ , MFR: 1.0 g/10 min, biomass degree 87%), Braskem Examples include low-density polyethylene derived from biomass manufactured by Co., Ltd. (trade name: SBC818, density: 0.918 g/cm ³ , MFR: 8.1 g/10 min, biomass degree 95%).

For example, linear low-density polyethylene derived from biomass is produced using sugarcane as a raw material. The degree of dispersion of such sugarcane-derived linear low density polyethylene can be 4 or more and 7 or less. On the other hand, the degree of dispersion of fossil-derived linear low-density polyethylene is usually 1.5 or more and 3.5 or less.

The outer thermoplastic resin layer 11 is preferably made of one or more of the above-mentioned low-density polyethylene derived from fossil fuel or biomass, linear low-density polyethylene, and linear low-density polyethylene using a metallocene catalyst. It may be a single layer or multiple layers containing. The outer thermoplastic resin layer 11 is formed by using one or more of the above resins, melt-extruding this using an extruder, etc., and melt-extruding and laminating it on the paper base layer 12. can be done. For example, the outer thermoplastic resin layer 11 is a single-layer thermoplastic resin layer containing low-density polyethylene. The thickness of the outer thermoplastic resin layer 11 is, for example, 15 μm or more and 35 μm or less.

The inner thermoplastic resin layer 16 is preferably made of one or more of the above-mentioned low-density polyethylene derived from fossil fuel or biomass, linear low-density polyethylene, and linear low-density polyethylene using a metallocene catalyst. It may be a single layer or multiple layers containing. The inner thermoplastic resin layer 16 is formed by using one or more of the above-mentioned resins, producing a resin film or sheet from this in advance, and applying the resin film or sheet via the adhesive layer 15. It can be formed by dry laminating the vapor-deposited film 14. The thickness of the inner thermoplastic resin layer 16 is, for example, 30 μm or more and 80 μm or less, preferably 40 μm or more and 60 μm or less.

[Paper base layer]
The paper base material layer 12 functions as a base material layer that holds the liquid paper container 100, and is preferably one that can provide the laminate with strength as a packaging product. The paper used as the paper base layer has a basis weight of 100 g/m ² or more and 700 g/m ² or less, preferably 150 g/m ² or more and 600 g/m ² or less, and more preferably 200 g/m ² or more and 500 g/m ² or less. It is something that you have. The paper base layer may be white paperboard in general, but from the viewpoint of safety, it is particularly preferable to use ivory paper using natural pulp, milk carton base paper, cup base paper, etc.

In addition, the paperboard used in the present invention may use neutral rosin, alkyl ketene dimer, alkenyl succinic anhydride as a sizing agent, and cationic polyacrylamide, cationic starch, etc. as a fixing agent. Good too. It is also possible to make paper in a neutral range of pH 6 or higher and pH 9 or lower using sulfuric acid band. In addition to the above-mentioned sizing agents, fixing agents, various fillers for paper manufacturing, retention aids, dry paper strength enhancers, wet paper strength enhancers, binders, dispersants, flocculants, plasticizers, etc., as necessary. It may contain an agent or an adhesive as appropriate.

[Printing layer]
The printing layer contains letters, numbers, pictures, figures, symbols, patterns, etc. for decoration, display of contents, display of expiration date, display of manufacturer, seller, etc., and for giving a sense of beauty. This layer forms any desired printed pattern. The printed layer can be provided as needed, and can be provided on the outer thermoplastic resin layer 11, for example. The printing layer may be provided on the entire surface of the outer thermoplastic resin layer 11, or may be provided on a part of the outer thermoplastic resin layer 11. The printing layer can be formed using conventionally known pigments and dyes, and the forming method is not particularly limited.

[Vapour-deposited film]
FIG. 2 is a cross-sectional view showing an example of the vapor-deposited film 14. The vapor-deposited film 14 includes a stretched plastic film 141, a transparent vapor-deposited layer 142 provided on the inner surface of the stretched plastic film 141, and a gas barrier coating film 143 provided on the transparent vapor-deposited layer 142. . The stretched plastic film 141 is in contact with the adhesive resin layer 13 , and the gas barrier coating film 143 is in contact with the adhesive layer 15 . Each layer will be explained below.

(Stretched plastic film)
The stretched plastic film 141 is a polyester film stretched in a predetermined direction. The stretched plastic film 141 may be a uniaxially stretched film stretched in one predetermined direction, or a biaxially stretched film stretched in two predetermined directions. The stretching direction of the stretched plastic film 141 is not particularly limited. For example, the stretched plastic film 141 may be stretched in the height direction of the liquid paper container constituted by the paper container packaging material 10, or may be stretched in the width direction of the liquid paper container.

The stretched plastic film 141 is a resin composition containing biomass-derived polyester (hereinafter also referred to as biomass polyester). Biomass polyester is a polyester whose diol units are biomass-derived ethylene glycol and whose dicarboxylic acid units are fossil fuel-derived dicarboxylic acids. The content of polyethylene terephthalate in the stretched plastic film 141 may be 80% by mass or more, 90% by mass or more, or 95% by mass or more. The stretched plastic film 141 contains, for example, 5% by mass or more of biomass polyester based on the entire resin composition of the stretched plastic film 141.

Biomass-derived ethylene glycol has the same chemical structure as conventional fossil fuel-derived ethylene glycol, so polyester films synthesized using biomass-derived ethylene glycol are mechanically superior to conventional fossil fuel-derived polyester films. There is no inferiority in terms of physical properties such as characteristics. Therefore, since the stretched plastic film 141 and the paper container packaging material 10 equipped with the same have a layer made of a carbon-neutral material, the stretched plastic film 141 and the paper container equipped with the same are manufactured from conventional raw materials obtained from fossil fuels. Compared to other packaging materials, the amount of fossil fuel used can be reduced and the environmental impact can be reduced.

Biomass-derived ethylene glycol is made from ethanol produced from biomass such as sugarcane and corn (biomass ethanol). For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol into ethylene glycol via ethylene oxide using a conventionally known method. Moreover, commercially available biomass ethylene glycol may be used, and for example, biomass ethylene glycol commercially available from India Glycol Corporation can be suitably used.

Dicarboxylic acid derived from fossil fuels is used as the dicarboxylic acid unit of the polyester. As the dicarboxylic acid, aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof can be used. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and examples of derivatives of aromatic dicarboxylic acids include lower alkyl esters of aromatic dicarboxylic acids, specifically methyl esters, ethyl esters, propyl esters, and butyl esters. Examples include esters. Among these, terephthalic acid is preferred, and as the aromatic dicarboxylic acid derivative, dimethyl terephthalate is preferred.

The resin composition forming the stretched plastic film 141 is made of fossil fuel-derived polyester, recycled polyester of fossil fuel-derived polyester products, recycled polyester of biomass-derived polyester products, etc. in a proportion of 5% by mass or more and 45% by mass or less. It may contain one species or two or more species.

Since carbon dioxide in the atmosphere contains ¹⁴ C at a certain rate (105.5 pMC), ^{the 14} C content in plants that grow by taking in atmospheric carbon dioxide, such as corn, is also around 105.5 pMC. It is known that It is also known that fossil fuels contain almost no ^14C . Therefore, by measuring the proportion of ¹⁴ C contained in all carbon atoms in polyester, the proportion of carbon derived from biomass can be calculated.

Biomass degree can be used as an index representing the ratio of raw materials derived from biomass. In this embodiment, "biomass degree" indicates the weight ratio of biomass-derived components. Taking polyethylene terephthalate as an example, polyethylene terephthalate is a polymerization of ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms in a molar ratio of 1:1, so only biomass-derived ethylene glycol can be used. When using polyethylene terephthalate, the weight ratio of biomass-derived components in polyethylene terephthalate is 31.25%, so the biomass degree is 31.25% (molecular weight derived from ethylene glycol derived from biomass / molecular weight of one polymerized unit of polyester). =60÷192).
In fossil fuel-derived polyester, the weight ratio of biomass-derived components is 0%, so the biomass degree of fossil fuel-derived polyester is 0%. In this embodiment, the biomass content in the stretched plastic film 141 is preferably 5.0% or more, more preferably 10.0% or more in order to exhibit the effect as a carbon offset material. . Further, the biomass content in the stretched plastic film 141 may be 30.0% or less due to problems in the film manufacturing process and physical properties.

The stretched plastic film 141 can be formed by forming the resin composition into a film by, for example, a T-die method. Specifically, after drying the resin composition described above, it is supplied to a melt extruder heated to a temperature (Tm) above the melting point of the resin composition to Tm + 70°C to melt the resin composition. For example, a film can be formed by extruding the material into a sheet from a die such as a T-die, and rapidly cooling and solidifying the extruded sheet material using a rotating cooling drum or the like. As the melt extruder, a single screw extruder, a twin screw extruder, a vent extruder, a tandem extruder, etc. can be used depending on the purpose.

The film obtained as described above is preferably biaxially stretched. Biaxial stretching can be performed by a conventionally known method. For example, the film extruded onto a cooling drum as described above is then heated by roll heating, infrared heating, etc., and stretched in the longitudinal direction to form a longitudinally stretched film. This stretching is preferably carried out using the difference in circumferential speed between two or more rolls. Longitudinal stretching is usually performed at a temperature range of 50°C or higher and 100°C or lower. Further, the longitudinal stretching ratio is preferably 2.5 times or more and 4.2 times or less, although it depends on the required characteristics of the film application. If the stretching ratio is less than 2.5 times, the thickness of the film becomes uneven and it is difficult to obtain a good film.

The longitudinally stretched film is then sequentially subjected to transverse stretching, heat setting, and heat relaxation to become a biaxially stretched film. The transverse stretching is usually performed at a temperature range of 50°C or higher and 100°C or lower. The transverse stretching ratio is preferably 2.5 times or more and 5.0 times or less, although it depends on the required characteristics of this use. If it is less than 2.5 times, the thickness of the film becomes uneven and it is difficult to obtain a good film, and if it exceeds 5.0 times, breakage is likely to occur during film formation.

After the transverse stretching, heat setting is subsequently performed, and the preferred temperature range for heat setting is Tg+70 to Tm-10°C of PET. Further, the heat setting time is preferably 1 second or more and 60 seconds or less. Furthermore, for applications requiring a reduction in thermal shrinkage rate, a thermal relaxation treatment may be performed as necessary.

The thickness of the stretched plastic film 141 obtained as described above is arbitrary depending on its use. The thickness of the stretched plastic film 141 is, for example, 5 μm or more, and may be 8 μm or more. Further, the thickness of the stretched plastic film 141 is, for example, 100 μm or less, may be 50 μm or less, may be 30 μm or less, or may be 25 μm or less. The range of the thickness of the stretched plastic film 141 can be determined by any combination of the above-mentioned lower limit candidate value and upper limit candidate value. In addition, the breaking strength of the film is 5 kgf/mm ² or more and 40 kgf/mm ² or less in the MD direction, and 5 kgf/mm ² or more and 35 kgf/mm ² or less in the TD direction, and the breaking elongation is 50% in the MD direction. 50% or more and 300% or less in the TD direction. Further, the shrinkage rate when left in a temperature environment of 150° C. for 30 minutes is 0.1% or more and 5% or less.

(Transparent vapor deposition layer)
The transparent vapor deposition layer 142 is a thin film of an inorganic oxide containing aluminum oxide as a main component. The transparent vapor deposition layer 142 may include an aluminum compound such as aluminum oxide or aluminum nitride, carbide, or hydroxide alone or a mixture thereof. Furthermore, the transparent vapor deposition layer 142 contains an aluminum compound as a main component, such as silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, magnesium oxide, titanium oxide, tin oxide, indium oxide, zinc oxide, zirconium oxide, etc. It may further contain metal oxides, metal nitrides, carbides, and mixtures thereof.

(Gas barrier coating film)
The gas barrier coating film 143 is for mechanically and chemically protecting the transparent vapor deposition layer 142 and improving the barrier properties of the vapor deposition film 14, and is laminated so as to be in contact with the transparent vapor deposition layer 142. The gas barrier coating film 143 is a cured film formed by a coating agent for a gas barrier coating film made of a resin composition containing a metal alkoxide, a water-soluble resin containing a hydroxyl group, and a silane coupling agent added as necessary. be.

The mass ratio of hydroxyl group-containing water-soluble resin/metal alkoxide in the resin composition is preferably 5/95 or more and 20/80 or less, and more preferably 8/92 or more and 15/85 or less. When it is smaller than the above range, the barrier effect of the barrier coating layer tends to be insufficient, and when it is larger than the above range, the rigidity and brittleness of the barrier coating layer tend to increase.

The thickness of the gas barrier coating film 143 is preferably 100 nm or more and 800 nm or less. If it is thinner than the above range, the barrier effect of the gas barrier coating film 143 tends to be insufficient, and if it is thicker than the above range, the rigidity and brittleness tend to increase.

The metal alkoxide has the general formula R ₁ nM(OR ₂ )m (wherein R ₁ and R ₂ represent a hydrogen atom or an organic group having 1 to 8 carbon atoms, M represents a metal atom, and n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the valence of M. Even if each of the plurality of R ₁ and R ₂ in one molecule is the same, (may be different)...Represented by (I).

Specific examples of the metal atom represented by M in the metal alkoxide include silicon, zirconium, titanium, aluminum, tin, lead, borane, and others. For example, alkoxy in which M is Si (silicon) Preference is given to using silanes.

In the above general formula (I), specific examples of OR ₂ include a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an i-propoxy group, a butoxy group, and a 3-methacryloxy group. Examples include alkoxy groups such as 3-acryloxy groups and phenoxy groups, and phenoxy groups.

In the above, specific examples of R ₁ include methyl group, ethyl group, n-propyl group, isopropyl group, phenyl group, p-styryl group, 3-chloropropyl group, trifluoromethyl group, vinyl group, γ-glycyl group, Examples include sidoxypropyl group, methacryl group, and γ-aminopropyl group.

Specific examples of alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraphenoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, Methyltributoxysilane, methyltriphenoxysilane, phenylphenoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxy Silane, isopropyltriethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, p-styryltrimethoxysilane, 3- Methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane Examples include various alkoxysilanes such as ethoxysilane, 3-chloropropyltriethoxysilane, trifluoromethyltrimethoxysilane, and 1,6-bis(trimethoxysilyl)hexane, and phenoxysilane. In this embodiment, condensation products of these alkoxysilanes can also be used, and specifically, for example, polytetramethoxysilane, polytetraethoxysilane, etc. can be used.

The silane coupling agent is used to adjust the crosslinking density of the cured film made of the metal alkoxide and the hydroxyl group-containing water-soluble resin to form a film with barrier properties and hot water treatment resistance.

The silane coupling agent has the general formula: R ₃ nSi(OR ₄ )4-n...(II)
(However, in the formula, R ₃ and R ₄ each independently represent an organic functional group, and n is 1 to 3.)
It is expressed as

In the above general formula (II), R ₃ is, for example, a hydrocarbon group such as an alkyl group or an alkylene group, an epoxy group, a (meth)acryloxy group, a ureido group, a vinyl group, an amino group, an isocyanurate group, or an isocyanate group. Examples include functional groups having the following. Specifically, at least one of two or three R ₃ 's is preferably a functional group having an epoxy group, such as a 3-glycidoxypropyl group and a 2-(3,4 epoxycyclohexyl) group. It is more preferable that Note that R ₃ may be the same or different.

In the above general formula (II), R ₄ is, for example, an organic functional group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 8 carbon atoms, which may have a branch, or an alkyl group having 3 to 8 carbon atoms. 7 is an alkoxyalkyl group. For example, examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, and the like. Examples of alkoxyalkyl groups having 3 to 7 carbon atoms include methyl ethyl ether, diethyl ether, methyl propyl ether, methyl isopropyl ether, ethyl propyl ether, ethyl isopropyl ether, methyl butyl ether, ethyl butyl ether, methyl sec-butyl ether, ethyl sec -butyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, and other linear or branched ethers with one hydrogen atom removed. Note that (OR ₄ ) may be the same or different.

Examples of the silane coupling agent represented by the above general formula (II) include 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane when n=1. When n=2, examples include 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane, and when n=3, examples include 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropyldimethylmethoxysilane, etc. Examples include sidoxypropyldimethylethoxysilane, 2-(3,4-epoxycyclohexyl)dimethylmethoxysilane, and 2-(3,4-epoxycyclohexyl)dimethylethoxysilane.

In particular, the crosslinking density of the cured film of the barrier coating layer using 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane is lower than that of the system using trialkoxysilane. Become. Therefore, while it is a film with excellent gas barrier properties and hot water treatment resistance, it becomes a flexible cured film and has excellent bending resistance, so packaging materials using this barrier film have gas barrier properties even after the Gelboflex test. Hard to deteriorate.

The silane coupling agent can be used as a mixture of n=1, 2, or 3, and the ratio and amount of the silane coupling agent used are determined by the design of the cured film of the barrier coating layer. .

The hydroxyl group-containing water-soluble resin can undergo dehydration co-condensation with a metal alkoxide, and the degree of saponification is preferably 90% or more and 100% or less, more preferably 95% or more and 100% or less, and 99% or more and 100% or less. % or less is more preferable. If the degree of saponification is smaller than the above range. The hardness of the barrier coating layer tends to decrease.

Specific examples of hydroxyl group-containing water-soluble resins include polyvinyl alcohol resins, ethylene-vinyl alcohol copolymers, polymers of bifunctional phenol compounds and bifunctional epoxy compounds, etc. They may be used, or two or more types may be used in combination, or they may be copolymerized. Among these, polyvinyl alcohol is particularly preferred because of its excellent flexibility and affinity, and polyvinyl alcohol-based resins are preferred.

Specifically, for example, polyvinyl alcohol resin obtained by saponifying polyvinyl acetate or ethylene/vinyl alcohol copolymer obtained by saponifying a copolymer of ethylene and vinyl acetate is used. can do.
Examples of such polyvinyl alcohol-based resins include PVA-124 (saponification degree = 99%, polymerization degree = 2,400) manufactured by Kuraray Co., Ltd., and Gohsenol NM-14 (saponification degree = 2,400) manufactured by Nippon Gosei Chemical Industry Co., Ltd. = 99%, degree of polymerization = 1,400).

(Preferred configuration of vapor deposited film)
Next, a preferred configuration of the vapor deposited film 14 in the thickness direction will be described with reference to FIG. 3. FIG. 3 shows a method using time-of-flight secondary ion mass spectrometry (TOF-SIMS) while repeating soft etching at a constant rate with a Cs (cesium) ion gun on the surface of the vapor-deposited film 14 on the gas barrier coating film 143 side. FIG. 3 is a diagram showing the results of measuring ions originating from the transparent vapor deposited layer 142 and ions originating from the stretched plastic film 141 using the method. The transparent deposited layer 142 of the deposited film 14 includes a transition region identified by the graphical analysis diagram shown in FIG.

The transition region is the peak position T ₂ of the elemental bond Al ₂ O ₄ H that transforms into aluminum hydroxide, which is detected by etching the vapor deposited film 14 from the gas barrier coating film 143 side using TOF-SIMS. and the interface T ₁ between the transparent vapor deposition layer 142 and the stretched plastic film 141. The interface T ₁ between the transparent vapor deposition layer 142 and the stretched plastic film 141 is specified as the position where the intensity of the graph of the element C ₆ is half of the intensity of the element C ₆ in the stretched plastic film 141 . In FIG. 3, the symbol W ₁ represents the thickness of the transition region.

The ratio of the thickness W ₁ of the transition region to the thickness of the transparent vapor deposition layer 142 (hereinafter also referred to as the metamorphism rate of the transition region) is preferably 5% or more and 60% or less. If the transformation rate exceeds 60%, the adhesion of the transparent vapor deposited layer 142 to the stretched plastic film 141 may decrease when heat is applied to the vapor deposited film 14. Further, the barrier properties of the vapor deposited film 14 against water vapor may be reduced. The metamorphosis rate may be 30% or less, 25% or less, or 20% or less. Further, the metamorphism rate may be 10% or more, or 15% or more. The range of metamorphism rates can be determined by any combination of the above-mentioned lower limit candidate value and upper limit candidate value.

The interface between the stretched plastic film 141 and the transparent vapor deposition layer 142 is subjected to mechanical and chemical stress due to heat. Therefore, in order to suppress deterioration of adhesion and barrier properties, it is important to firmly cover the stretched plastic film 141 with the transparent vapor deposited layer 142 at the interface between the stretched plastic film 141 and the transparent vapor deposited layer 142.

Aluminum hydroxide has good adhesion to plastic substrates due to its chemical structure, and since it itself forms a dense network, it has high water vapor barrier properties. However, the bond structure based on hydrogen bonds between aluminum hydroxide and the base material tends to microscopically collapse under heat stress. Furthermore, the aluminum hydroxide network easily penetrates into the membrane due to the affinity between water molecules and the grain boundaries of aluminum hydroxide.

In this embodiment, in order to minimize the transition region formed by aluminum hydroxide in the aluminum oxide vapor-deposited film at the interface with the plastic base material, we will focus on the elemental bond Al ₂ O ₄ H and control its abundance. By suppressing aluminum hydroxide generated from elemental bonds Al ₂ O ₄ H due to heat stress, and increasing the ratio of aluminum oxide film with relatively little aluminum hydroxide, microscopic vapor deposition by water molecules caused by heat stress is suppressed. It is intended to suppress membrane destruction and interface destruction with the plastic base material. Thereby, a vapor deposited film 14 having unprecedented adhesiveness and barrier properties can be provided.

The aluminum oxide vapor-deposited film can be formed by forming a vapor-deposited film on the surface of a plastic substrate that has been pretreated with oxygen plasma. As the vapor deposition method for forming the vapor deposited film, various vapor deposition methods can be applied from among physical vapor deposition and chemical vapor deposition. Physical vapor deposition methods can be selected from the group consisting of vapor deposition, sputtering, ion plating, ion beam assist, and cluster ion beam methods, and chemical vapor deposition methods include plasma CVD, plasma polymerization, and thermal It can be selected from the group consisting of CVD method and catalytic reaction type CVD method. In this embodiment, a physical vapor deposition method is suitable.

A specific example of a method for obtaining the graph of FIG. 3 will be described. First, using Cs, etching is performed from the outermost surface of the gas barrier coating film 143 to form elemental bonds at the interface between the gas barrier coating film 143, the transparent vapor deposition layer 142, and a film such as the stretched plastic film 141, and elemental bonds in the vapor deposition film. conduct an analysis of Thereby, the graph shown in FIG. 3 can be obtained.

Next, a specific example of a method for analyzing the graph of FIG. 3 will be described. Here, a case will be described in which the gas barrier coating film 143 contains silicon oxide.

First, in the graph, the position where the strength of SiO ₂ (mass number 59.96), which is a constituent element of the gas barrier coating film 143, is half the strength of the gas barrier coating film 143 is located between the gas barrier coating film 143 and the transparent vapor-deposited film. It is identified as the interface of layer 142. Next, the position where the strength of C ₆ (mass number 72.00), which is the constituent material of the stretched plastic film 141, is half of the strength in the stretched plastic film 141 is set as the interface between the stretched plastic film 141 and the transparent vapor deposition layer 142. Identify. Further, the distance between the two interfaces in the thickness direction is employed as the thickness of the transparent vapor deposition layer 142.

Next, a peak representing the measured elemental bond Al ₂ O ₄ H (mass number 118.93) is determined, and the region from the peak to the interface is defined as a transition region. However, when the gas barrier coating film 143 is composed of a material having the same mass number as Al ₂ O ₄ H (mass number 118.93), it is necessary to separate the waveform of 118.93.

When the reactant AlSiO 4 and the hydroxide Al 2 O 4 H occur at the interface between the gas barrier coating film 143 and the transparent vapor deposited layer 142, the reactant AlSiO ₄ and the hydroxide Al ₂ O ₄ H occur at the interface between them and the stretched plastic film 141 and the transparent vapor deposited layer 142. The Al ₂ O ₄ H present can be separated off. In this way, the waveform separation can be handled appropriately depending on the material of the gas barrier coating film 143.

In waveform separation, for example, a profile with a mass number of 118.93 obtained by TOF-SIMS is subjected to nonlinear curve fitting using a Gaussian function, and overlapping peaks are separated using a least squares method Levenberg Marquardt algorithm. It can be carried out.

[Adhesive resin layer]
The adhesive resin layer 13 is a layer that includes an adhesive resin and adheres the base material including the paper base material layer 12 and the film including the vapor-deposited film 14. The adhesive resin layer 13 is formed by, for example, a sand lamination method.

The adhesive resin of the adhesive resin layer 13 preferably contains one or more compounds selected from the group consisting of epoxy group-containing compounds, silane group-containing compounds, carboxylic acid group-containing compounds, and acid anhydride-containing compounds. It is a resin composition containing. For example, polyethylene resin or polypropylene resin can be used. Thereby, it is possible to reduce the thermal stress that the vapor deposited film 14 receives in the step of bonding the paper base layer 12 and the stretched plastic film 141 of the vapor deposited film 14 via the adhesive resin layer 13 by the sand lamination method. Thereby, it is possible to suppress the gas barrier properties of the vapor-deposited film 14 from deteriorating. Furthermore, since the adhesiveness between the adhesive resin layer 13 and the stretched plastic film 141 of the vapor-deposited film 14 is high, the anchor coat layer between the adhesive resin layer 13 and the stretched plastic film 141 can be made unnecessary. That is, the adhesive resin layer 13 can be provided such that the outer surface of the stretched plastic film 141 is in direct contact with the adhesive resin layer 13.

When polyethylene resin is used as the adhesive resin constituting the adhesive resin layer 13, the density is preferably in the range of 920 to 970 kg/m ³ and more preferably in the range of 920 to 965 kg/m ³ because it has excellent heat resistance. preferable. By setting the density of the adhesive resin constituting the adhesive resin layer 13 within the above range, when heat is applied to the packaging material 10 for paper containers, the generation of pinholes and the peeling and wrinkles of the transparent vapor deposited layer 142 can be effectively prevented. can be suppressed. Furthermore, it is also possible to suppress the generation of thermal pinholes caused by heat during the production of liquid paper containers. The melting point of the adhesive resin constituting the adhesive resin layer 13 is desirably higher than the melting point of the inner thermoplastic resin layer 16 . For example, the melting point is preferably 90°C or higher, more preferably 100°C or higher.

As the adhesive resin constituting the adhesive resin layer 13, a polyethylene resin is preferable in consideration of adhesiveness with the paper base layer 12 and the vapor deposited film 14. Such polyethylene resins include ethylene homopolymers, ethylene/α-olefin copolymers, and compositions thereof, and the molecular chain form may be linear, with a long chain having 6 or more carbon atoms. It may have chain branching.

Examples of the ethylene homopolymer include medium- and low-pressure ethylene homopolymers, high-pressure low-density polyethylene, and the like. The medium/low pressure ethylene homopolymer can be obtained by a conventionally known medium/low pressure ionic polymerization method. Further, high-pressure low density polyethylene can be obtained by a conventionally known high-pressure radical polymerization method.

The α-olefin used in the ethylene/α-olefin copolymer includes propylene, 1-butene, 4-methyl-1-pentene, 3-methyl-1-butene, 1-pentene, 1-hexene, and 1-heptene. , 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, etc., and one or more of these may be used. The method for obtaining the ethylene/α-olefin copolymer is not particularly limited, and examples include high, medium, and low pressure ionic polymerization methods using Ziegler-Natta catalysts, Phillips catalysts, and single-site catalysts. can. Such copolymers can be conveniently selected from commercially available products.

Examples of the epoxy group-containing compound contained in the adhesive resin constituting the adhesive resin layer 13 include epoxidized vegetable oil (epoxidation of unsaturated double bonds in natural vegetable oil), glycidyl ether type, glycidyl amine type, glycidyl ester type, etc. can be mentioned. Among these, epoxidized vegetable oil is more preferred from the viewpoint of safety when used in food packaging materials. For example, epoxidized soybean oil, epoxidized linseed oil, epoxidized olive oil, epoxidized safflower oil, epoxidized corn oil, etc. are used. The content of such an epoxy group-containing compound is, for example, 0.01 to 10 parts by weight, preferably 0.01 to 5.0 parts by weight, based on 100 parts by weight of the adhesive resin constituting the adhesive resin layer 13. . If it is less than 0.01 part by weight, the adhesive strength with the vapor-deposited film 14 will be insufficient, and if it exceeds 10 parts by weight, it will cause blocking and, especially when used for food packaging, it will be accompanied by an odor, which is not preferable.

As the silane group-containing compound contained in the adhesive resin constituting the adhesive resin layer 13, a silane oligomer is suitably used. More specifically, in order to improve adhesiveness, a silane oligomer containing any one of an epoxy group, a mercapto group, and an alkoxy group, or several of these groups in the molecule is desirable. The silane oligomer is blended in an amount of 0.01 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the adhesive resin constituting the adhesive resin layer 13. If the amount of the silane oligomer is less than 0.01 parts by weight, the adhesive strength with the vapor-deposited film 14 will be insufficient, and if it exceeds 10 parts by weight, the molding process will be poor, which is not preferable.

As the carboxylic acid group-containing compound contained in the adhesive resin constituting the adhesive resin layer 13, an ethylene-unsaturated carboxylic acid or a copolymer with an ester thereof can be used. More specific examples include ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, and ethylene-methyl methacrylate copolymer. It is also possible to use an ionomer resin in which molecules of ethylene-unsaturated carboxylic acid are cross-linked with metal ions.

The acid anhydride-containing compound contained in the adhesive resin constituting the adhesive resin layer 13 is preferably a maleic acid-modified polyolefin resin such as a maleic acid-modified polyethylene resin or a maleic acid-modified polypropylene resin. More preferred are maleic anhydride-modified polyolefin resins such as polyethylene resins and maleic anhydride-modified polypropylene resins. Note that the maleic acid-modified polyolefin resin is obtained by graft polymerizing maleic acid to a polyolefin resin.

The thickness of the adhesive resin layer 13 is also not particularly limited, but is preferably 15 μm or more and 40 μm or less. By setting the thickness of the adhesive resin layer 13 within the above range, it is possible to effectively suppress the generation of thermal pinholes when molding a liquid paper container. Note that if the thickness is less than 15 μm, there is a risk that the adhesiveness between the paper base layer 12 and the vapor-deposited film 14 will be insufficient. Furthermore, if the thickness exceeds 40 μm, the characteristics of the transparent vapor deposited layer 142 of the vapor deposited film 14 may deteriorate due to heat stress during the process of laminating the paper base layer 12 and the vapor deposited film 14 using a molten adhesive resin. There is a risk of deterioration.

In addition to the above-mentioned various compounds, the resin constituting the adhesive resin layer 13 may optionally contain antioxidants, light stabilizers, antistatic agents, lubricants, antiblocking agents, etc. that are commonly used in polyolefin resins. Additives may be added as long as they do not impair the purpose of the present invention.

[Adhesive layer]
The adhesive layer 15 is a layer for bonding the film containing the vapor-deposited film 14 and the film containing the inner thermoplastic resin layer 16 by dry lamination. The adhesive layer 15 is formed by applying an adhesive to the surface of the film that is to be laminated between the film containing the vapor-deposited film 14 and the film containing the inner thermoplastic resin layer 16 and drying it. Examples of the adhesive constituting the adhesive layer 15 include one-component or two-component hardening or non-curing vinyl-based, (meth)acrylic-based, polyamide-based, polyester-based, polyether-based, polyurethane-based, Solvent-based, water-based, or emulsion-based adhesives such as epoxy, rubber, and other adhesives can be used. As the two-component curing adhesive, a cured product of a polyol and an isocyanate compound can be used. The coating method for the above adhesive may be, for example, a direct gravure roll coating method, a gravure roll coating method, a kiss coating method, a reverse roll coating method, a Fontaine method, a transfer roll coating method, or other methods.

The adhesive layer 15 may contain a biomass-derived component. For example, when the adhesive layer 15 contains a cured product of a polyol and an isocyanate compound, at least either the polyol or the isocyanate compound may contain a biomass-derived component.

By adhering the film including the vapor-deposited film 14 and the film including the inner thermoplastic resin layer 16 by the dry lamination method, damage caused by heat to the vapor-deposited film 14 can be prevented compared to when using the sand lamination method. Can be suppressed. For example, it is possible to prevent the transparent vapor deposited layer 142 from peeling off from the stretched plastic film 141 or to prevent the gas barrier properties of the vapor deposited film 14 from deteriorating.

<Method for manufacturing packaging materials>
Next, an example of a method for manufacturing the packaging material 10 for paper containers will be described. First, an example of a method for manufacturing the vapor-deposited film 14 will be described.

(Manufacturing process of vapor deposited film)
First, a stretched plastic film 141 is prepared. Subsequently, a transparent vapor deposition layer 142 containing aluminum oxide is formed on the inner surface of the stretched plastic film 141. FIG. 4 is a diagram showing an example of the film forming apparatus 60. The film forming apparatus 60 and a film forming method using the film forming apparatus 60 will be described below.

As shown in FIG. 4, in the film forming apparatus 60, partition walls 85a to 85c are formed in the reduced pressure chamber 62. The partition walls 85a to 85c form a substrate transfer chamber 62A, a plasma pretreatment chamber 62B, and a film formation chamber 62C, and in particular, a plasma pretreatment chamber 62B and a film formation chamber are defined as spaces surrounded by the partition walls 85a to 85c. 62C is formed, and each chamber is further formed with an exhaust chamber therein as required.

The plasma pretreatment chamber 62B and the plasma pretreatment process in the plasma pretreatment chamber 62B will be described. Inside the plasma pretreatment chamber 62B, a part of a plasma pretreatment roller 70 that conveys the stretched plastic film 141 to be pretreated and enables plasma treatment is provided so as to be exposed to the substrate conveyance chamber 62A. ing. The stretched plastic film 141 moves to the plasma pretreatment chamber 62B while being wound up.

The plasma pretreatment chamber 62B and the film forming chamber 62C are provided in contact with the substrate transport chamber 62A, and can move the stretched plastic film 141 without exposing it to the atmosphere. Further, the pretreatment chamber 62B and the substrate transfer chamber 62A are connected through a rectangular hole, and a part of the plasma pretreatment roller 70 protrudes toward the substrate transfer chamber 62A through the rectangular hole. A gap is formed between the wall of the transport chamber and the pretreatment roller 70, and the stretched plastic film 141 can be moved from the substrate transport chamber 62A to the film forming chamber 62C through the gap. The structure is similar between the base material transport chamber 62A and the film forming chamber 62C, and the stretched plastic film 141 can be moved without being exposed to the atmosphere.

The base material transport chamber 62A serves as a winding means for winding up into a roll the stretched plastic film 141 with a vapor deposited film formed on one side, which has been moved to the base material transport chamber 62A again by the film forming roller 75. A take-up roller is provided so that the stretched plastic film 141 on which the vapor-deposited film is formed can be taken up.

When manufacturing the vapor deposited film 14 having the aluminum oxide vapor deposited film, the plasma pretreatment chamber 62B is configured to separate the space where plasma is generated from other areas and efficiently evacuate the opposing space. , it becomes easier to control the plasma gas concentration, and productivity is improved. The pretreatment pressure for forming the reduced pressure can be set and maintained at approximately 0.1 Pa or more and 100 Pa or less, and in particular, the treatment pressure of oxygen plasma pretreatment to achieve a metamorphosis rate in a preferable transition region of the aluminum oxide vapor deposited film. The pressure is preferably 1 Pa or more and 20 Pa or less, may be 10 Pa or less, or may be 5 Pa or less. The pretreatment pressure range can be determined by any combination of the lower limit candidate value and the upper limit candidate value described above.

The conveyance speed of the stretched plastic film 141 is not particularly limited, but from the viewpoint of production efficiency, it can be at least 200 to 1000 m/min. The transport speed for treatment is preferably 300 to 800 m/min.

The plasma pretreatment roller 70 constituting the plasma pretreatment device prevents the stretched plastic film 141 from shrinking or breaking due to heat during plasma treatment by the plasma pretreatment means, and uniformly applies oxygen plasma P to the stretched plastic film 141. It is intended to be applied over a wide range of areas. Preferably, the temperature of the pretreatment roller 70 can be adjusted to a constant temperature between -20° C. and 100° C. by adjusting the temperature of a temperature adjusting medium circulating within the pretreatment roller.

The plasma pretreatment means includes a plasma supply means and a magnetic formation means. The plasma pretreatment means cooperates with the plasma pretreatment roller 70 to confine the oxygen plasma P near the surface of the stretched plastic film 141.

The plasma pretreatment means is provided so as to partially cover the pretreatment roller 70. Specifically, plasma supply means 72 and magnetic formation means 73, which constitute plasma pretreatment means, are arranged along the surface near the outer periphery of pretreatment roller 70. The plasma supply means 72 includes a plasma supply nozzle that supplies plasma source gas. The magnetic formation means 73 includes a magnet or the like to promote generation of plasma P. Further, the plasma pretreatment means includes an electrode 71 to which a voltage is applied between the pretreatment roller 70 and the electrode 71 . Although FIG. 4 shows an example in which the electrode 71 and the plasma supply means 72 are separate members, the present invention is not limited to this. Although not shown, the electrode 71 and the plasma supply means 72 may be constituted by an integral member.

Plasma P is generated in the space sandwiched between the pretreatment roller 70 and the magnetic forming means 73, and a region with high plasma density is formed near the surfaces of the pretreatment roller 70 and the stretched plastic film 141. The inner surface of the film 141 can be subjected to oxygen plasma pretreatment to form a plasma treated surface.

The plasma supply means 72 of the plasma pretreatment means includes a raw material volatilization supply device 68 connected to a plasma supply nozzle provided outside the decompression chamber 62, and a raw material gas supply line that supplies raw material gas from the device. The plasma raw material gas to be supplied is oxygen alone or a mixed gas of oxygen gas and an inert gas, and is supplied from the gas storage section through a flow rate controller while measuring the flow rate of the gas. Examples of the inert gas include one or more mixed gases selected from the group consisting of argon, helium, and nitrogen.

These supplied gases are mixed at a predetermined ratio as necessary to form a plasma raw material gas alone or a mixed gas for plasma formation, and are supplied to the plasma supply means. The single or mixed gas is supplied to a plasma supply nozzle of the plasma supply means, and is supplied near the outer periphery of the pretreatment roller 70 where the supply port of the plasma supply nozzle opens. The nozzle opening is directed toward the stretched plastic film 141 on the pretreatment roller 70, and is arranged and configured so that the oxygen plasma P can be uniformly diffused and supplied over the entire surface of the stretched plastic film 141. Thereby, uniform plasma pretreatment can be applied to a large area of the stretched plastic film 141.

In order to set the metamorphosis rate in the transition region of the aluminum oxide vapor-deposited film to 5% or more and 60% or less as described above, the oxygen plasma pretreatment requires a mixing ratio of oxygen gas and inert gas (oxygen gas/inert gas). is preferably 1/1 or more, may be 3/2.5 or more, or may be 3/2 or more. Further, the mixing ratio of oxygen gas and the inert gas (oxygen gas/inert gas) is preferably 6/1 or less, may be 3/1 or less, or may be 5/2 or less. By setting the mixing ratio to 1/1 or more and 6/1 or less, the energy for forming a film of vapor-deposited aluminum on the plastic film increases, and by setting the mixing ratio to 3/2 or more and 5/2 or less, the formation of aluminum hydroxide is increased. is formed near the interface of the plastic film, that is, the rate of metamorphosis in the transition region is reduced. The range of the mixing ratio of oxygen gas and the inert gas (oxygen gas/inert gas) can be determined by any combination of the above-mentioned lower limit candidate value and upper limit candidate value.

The electrode 71 functions as a counter electrode of the pretreatment roller 70. The plasma raw material gas supplied is excited due to the potential difference due to the high frequency voltage, low frequency voltage, etc. supplied between the pretreatment roller 70 and the plasma P, which is generated and supplied.

Specifically, for the electrode 71, a plasma pretreatment roller is installed as a plasma power source, and an alternating current voltage with a frequency of 10 Hz to 2.5 GHz is applied between the electrode 71 and the opposing electrode to control input power, impedance, etc. , and the plasma pretreatment roller 70 can be applied with any voltage. The film forming apparatus 60 includes a power source 82 that can apply a bias voltage to bring the oxygen plasma P, which can physically or chemically modify the surface properties of the stretched plastic film 141, to a positive potential.

The plasma intensity per unit area is preferably 50 W·sec/m ² or more and 8000 W·sec/m ² or less. At 50 W/sec/m ² or less, no effect of plasma pretreatment is observed, and at 8,000 W/sec/m ² or more, plasma causes deterioration of the stretched plastic film 141 such as consumption, damage, coloring, and baking of the stretched plastic film 141. tends to occur. In particular, the plasma intensity per unit area is preferably 100 W·sec/m ² or more. Further, the plasma intensity per unit area is preferably 1000 W·sec/m ² or less, more preferably 500 W·sec/m ² or less, and may be 300 W·sec/m ² or less. By applying a bias voltage perpendicularly to the stretched plastic film 141 to provide the plasma intensity described above, it is possible to stably improve the adhesion with the aluminum oxide vapor deposited film. The range of plasma intensity per unit area can be determined by any combination of the above-mentioned lower limit candidate value and upper limit candidate value.

As the magnetic formation means 73, it is possible to use one in which an insulating spacer and a base plate are provided in a magnet case, and a magnet is provided on the base plate. An insulating shield plate is provided in the magnet case, and an electrode can be attached to this insulating shield plate. The magnet case and the electrodes are electrically insulated, and even if the magnet case is installed and fixed in the decompression chamber 62, the electrodes can be kept at an electrically floating level. By providing a magnet, the reactivity near the surface of the stretched plastic film 141 increases, making it possible to form a good plasma pretreated surface at high speed.

Preferably, the magnet is configured such that the magnetic flux density at the surface of the stretched plastic film 141 is between 10 Gauss and 10,000 Gauss. If the magnetic flux density on the surface of the stretched plastic film 141 is 10 Gauss or more, it becomes possible to sufficiently increase the reactivity near the surface of the stretched plastic film 141, and a good pretreated surface can be formed at high speed.

Next, the film forming process in the film forming chamber 62C and the film forming chamber 62C will be explained. The film forming apparatus 60 includes a film forming roller 75 arranged in a reduced pressure film forming chamber 62C, and a target of a vapor deposition film forming means 74 arranged opposite to the film forming roller 75. The film forming roller 75 wraps and conveys the stretched plastic film 141, which has been pretreated in the plasma pretreatment device, with the treated surface of the stretched plastic film 141 facing outward. In the film forming step, the target of the vapor deposition film forming means 74 is evaporated to form an aluminum oxide film on the surface of the stretched plastic film 141.

The vapor deposition film forming means 74 is, for example, a resistance heating type, and uses an aluminum metal wire as an evaporation source, and evaporates aluminum oxide onto the surface of the stretched plastic film 141 while supplying oxygen to oxidize the aluminum vapor. A film is formed.

The thickness of the transparent vapor deposition layer 142 including the aluminum oxide vapor deposition film formed as described above is preferably 3 nm or more, may be 8 nm or more, or may be 10 nm or more. Moreover, the thickness of the transparent vapor deposition layer 142 is preferably 50 nm or less, may be 30 nm or less, may be 20 nm or less, may be 15 nm or less, or may be 14 nm or less. The thickness range of the transparent vapor deposition layer 142 can be determined by any combination of the lower limit candidate value and the upper limit candidate value described above. Within this range, barrier properties can be maintained. However, if the deposited aluminum oxide film is very thin, it becomes difficult to calculate the metamorphosis rate in the transition region by TOF-SIMS measurement.

Next, a method for forming the gas barrier coating film 143 on the transparent vapor deposition layer 142 will be explained. First, the metal alkoxide, silane coupling agent, hydroxyl group-containing water-soluble resin, reaction promoter (sol-gel method catalyst, acid, etc.), and an organic solvent such as water, methyl alcohol, ethyl alcohol, isopropanol, etc. as a solvent are first added. By mixing, a coating agent for a gas barrier coating film made of a resin composition is prepared.

Next, the above coating agent for a gas barrier coating film is applied onto the transparent vapor deposited layer 142 by a conventional method and dried. Through this drying step, the condensation or co-condensation reaction further advances and a coating film is formed. The above coating operation may be further repeated on the first coating film to form a plurality of coating films consisting of two or more layers.

Further, heat treatment is performed for 3 seconds to 10 minutes at a temperature in the range of 20 to 200°C, preferably 50 to 180°C, and at a temperature below the softening point of the resin constituting the base layer. As a result, a gas barrier coating film 143 made of the above gas barrier coating film coating agent can be formed on the transparent vapor deposition layer 142. In this way, the vapor deposited film 14 having the stretched plastic film 141, the transparent vapor deposited layer 142, and the gas barrier coating film 143 can be produced.

(Preparation process for inner thermoplastic resin layer)
Next, a film constituting the inner thermoplastic resin layer 16 is prepared. When the inner thermoplastic resin layer 16 includes a plurality of layers, the film constituting the inner thermoplastic resin layer 16 is, for example, a co-extrusion film produced by co-extrusion.

(Lamination process of vapor deposited film and inner thermoplastic resin layer)
Next, the vapor deposited film 14 and the inner thermoplastic resin layer 16 are laminated with the adhesive layer 15 interposed therebetween by a dry lamination method. In the dry lamination method, first, an adhesive composition is applied to one of the two films to be laminated. Specifically, the adhesive composition is applied to either the gas barrier coating film 143 constituting the inner surface 14x of the vapor-deposited film 14 or the inner thermoplastic resin layer 16. Preferably, an adhesive composition is applied to the gas barrier coating film 143. Subsequently, the applied adhesive composition is dried to evaporate the solvent. Thereafter, the two films are laminated via the dried adhesive composition. Subsequently, the two laminated films are rolled up and aged for 72 hours or more in an environment of 30° C. or higher, for example. As a result, as shown in FIG. 5, the first laminate 20 includes, in order from the outside to the inside, a stretched plastic film 141, a transparent vapor deposition layer 142, a gas barrier coating film 143, an adhesive layer 15, and an inner thermoplastic resin layer 16. can be obtained. The inner surface 20x of the first laminate 20 is constituted by the inner thermoplastic resin layer 16, and the outer surface 20y is constituted by the stretched plastic film 141.

(Lamination step of first laminate and paper base layer)
Next, the first laminate 20 and the paper base material layer 12 are laminated with the adhesive resin layer 13 interposed therebetween by a sand lamination method. FIG. 6 is a diagram showing a laminating apparatus 90 that laminates the first laminate 20 and the paper base layer 12.

In the lamination process using the lamination device 90, first, as shown in FIG. 6, the paper base material layer 12 is unwound from the first supply roll 91. Further, the first laminate 20 is unwound from the second supply roll 92 . Subsequently, a molten adhesive resin 13A for forming the adhesive resin layer 13 is extruded between the inner surface of the paper base layer 12 and the stretched plastic film 141 of the first laminate 20. Thereby, it is possible to obtain a second laminate 25 in which the paper base material layer 12 and the first laminate 20 are laminated with the adhesive resin layer 13 in between. Note that an anchor coat layer may be provided on the inner surface of the paper base layer 12 before extruding the molten adhesive resin 13A. Thereby, the adhesion between the paper base layer 12 and the adhesive resin layer 13 can be improved. As the anchor coat layer, a layer made of any resin having a heat resistance temperature of 135° C. or higher, such as vinyl modified resin, epoxy resin, urethane resin, polyester resin, polyethyleneimine, etc., can be used.

Incidentally, the higher the temperature of the adhesive resin 13A in a molten state is, the higher the temperature of the transparent vapor deposited layer 142 of the vapor deposited film 14 laminated by the sand lamination method becomes. If the temperature of the transparent vapor deposition layer 142 becomes too high, the characteristics of the transparent vapor deposition layer 142 containing aluminum oxide may deteriorate. For example, it is conceivable that the transparent vapor deposited layer 142 may peel off from the stretched plastic film 141 or that the gas barrier properties of the vapor deposited film 14 may deteriorate. Therefore, in order to suppress deterioration of the characteristics of the transparent vapor deposition layer 142, it is preferable that the temperature of the adhesive resin 13A in the molten state is low. For example, the temperature of the adhesive resin 13A in a molten state is preferably 330°C or lower, more preferably 320°C or lower.

Preferably, the adhesive resin 13A and the adhesive resin layer 13 are made of one or more selected from the group consisting of epoxy group-containing compounds, silane group-containing compounds, carboxylic acid group-containing compounds, and acid anhydride-containing compounds, as described above. It is a resin composition containing two or more types of compounds. Thereby, the melting point of the adhesive resin 13A can be lowered, so the temperature of the adhesive resin 13A in a molten state can be lowered. Therefore, deterioration of the characteristics of the transparent vapor deposited layer 142 containing aluminum oxide during sand lamination can be suppressed. Further, it is possible to suppress the occurrence of pinholes in the adhesive resin layer 13, vapor deposited film 14, adhesive layer 15, inner thermoplastic resin layer 16, etc. due to evaporation of moisture in the paper base layer 12. Further, the resin composition containing one or more compounds selected from the group consisting of an epoxy group-containing compound, a silane group-containing compound, a carboxylic acid group-containing compound, and an acid anhydride-containing compound is a stretched plastic film 141. Adhesive to the polyethylene that makes up the material. Therefore, even if the stretched plastic film 141 is not provided with an anchor coat layer, peeling of the adhesive resin layer 13 from the stretched plastic film 141 can be suppressed.

Thereafter, the outer thermoplastic resin layer 11 may be formed on the outer surface of the second laminate 25 in the same line as the laminating device 90. For example, as shown in FIG. 6, a molten thermoplastic resin 11A for forming the outer thermoplastic resin layer 11 is extruded onto the outer surface of the paper base layer 12 of the second laminate 25. As a result, a paper container packaging material 10 including an outer thermoplastic resin layer 11, a paper base layer 12, an adhesive resin layer 13, a vapor-deposited film 14, an adhesive layer 15, and an inner thermoplastic resin layer 16 can be obtained.

Hereinafter, the advantages brought about by the packaging material 10 for paper containers in this embodiment will be explained.

In this embodiment, as described above, the vapor-deposited film 14 and the inner thermoplastic resin layer 16 are bonded together by dry lamination with the gas-barrier coating film 143 of the vapor-deposited film 14 facing inward. Therefore, when bonding the first laminate 20 including the vapor-deposited film 14 and the paper base layer 12 by the sand lamination method, the heat of the molten adhesive resin 13A constituting the adhesive resin layer 13 makes the vapor-deposited film 14 transparent. It can be suppressed from reaching the vapor deposited layer 142. Thereby, peeling of the transparent vapor deposited layer 142 from the stretched plastic film 141 and deterioration of the gas barrier properties of the vapor deposited film 14 due to heat can be suppressed. Therefore, even when aluminum oxide, which is weaker in heat than silicon oxide, is used as the transparent vapor deposition layer 142, it is possible to prevent the barrier properties of the vapor deposition film 14 from deteriorating. Furthermore, by using the transparent vapor deposition layer 142 of aluminum oxide, a physical vapor deposition method can be employed as a method for forming the transparent vapor deposition layer 142. Thereby, the productivity of the vapor deposited film 14 can be increased compared to the case where chemical vapor deposition is employed.

<Liquid paper container>
The paper container packaging material 10 is used as a material for forming a liquid paper container. Because liquid paper containers have excellent barrier properties, they can be used for alcoholic beverages such as sake, shochu, and wine, milk beverages such as milk, foods such as soft drinks such as orange juice and tea, and chemical products such as car wax, shampoo, and detergents. It can be suitably used as a wrapping paper container for liquids in general. FIG. 7 is a perspective view showing an example of a liquid paper container 100 formed from the paper container packaging material 10.

The liquid paper container 100 shown in FIG. 7 has a rectangular cylindrical body 101 including side surfaces, a rectangular plate-shaped bottom 102, and an upper part 103, and is a so-called Goebel top type container. The upper part 103 has a pair of opposing inclined plates 104 and a pair of folding parts 105 located between the pair of inclined plates 104 and folded between the inclined plates 104. Further, the pair of inclined plates 104 are adhered to each other by an adhesive margin 106 provided at the upper end of each plate. Note that a spout may be attached to one of the pair of inclined plates 104, and the spout may be sealed with a cap. Alternatively, a flat-top container may be formed.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist thereof.

[Example A1]
First, a biomass-derived PET film having a thickness of 12 μm was prepared as the stretched plastic film 141 of the vapor-deposited film 14 . The biomass-derived PET film was obtained by the following method.

After esterifying 83 parts by mass of fossil fuel-derived terephthalic acid and 62 parts by mass of biomass-derived ethylene glycol (manufactured by India Glycol) by a conventional direct gravity method, a polycondensation reaction was carried out under reduced pressure. and obtained biomass-derived polyethylene terephthalate. When the obtained biomass-derived polyethylene terephthalate was subjected to radiocarbon measurement, the biomass degree as determined by radiocarbon (C14) measurement was 31.25%.
60 parts by mass of the above-mentioned biomass-derived polyethylene terephthalate, 30 parts by mass of fossil fuel-derived polyethylene terephthalate, and 10 parts by mass of a masterbatch containing fossil fuel-derived polyethylene terephthalate were fed into an extruder, and a sheet was formed from a T-die. The mixture was extruded and cooled and solidified using a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched in the longitudinal direction and then in the transverse direction to obtain a biaxially stretched PET film having a thickness of 12 μm. The biomass degree of the obtained biaxially stretched PET film was measured and found to be 18.8%.

Subsequently, using the above-mentioned film forming apparatus 60 shown in FIG. A transparent vapor deposition layer 142 having a thickness of 12 nm was formed.
(Oxygen plasma pretreatment conditions)
・Plasma intensity: 150W・sec/m ²
・Mixing ratio of oxygen gas and inert gas: oxygen/argon = 2/1
・Voltage applied between pre-treatment drum and plasma supply nozzle: 340V
・Pretreatment pressure: 3.8Pa
(Aluminum oxide film forming conditions)
・Vacuum degree: 8.1×10 ^-2 Pa
・Transportation speed: 400m/min
・Oxygen gas supply amount: 20000sccm

Subsequently, a gas barrier coating film 143 was formed on the transparent vapor deposition layer 142. Specifically, first, 385 g of water, 67 g of isopropyl alcohol, and 9.1 g of 0.5N hydrochloric acid were mixed, and 175 g of tetraethoxysilane as a metal alkoxide and glycide as a silane coupling agent were added to a solution adjusted to pH 2.2. Solution A was prepared by mixing 9.2 g of oxypropyltrimethoxysilane while cooling to 10°C.
A solution B was prepared by mixing 14.7 g of polyvinyl alcohol with a polymerization degree of 2400 with a saponification value of 99% or higher, 324 g of water, and 17 g of isopropyl alcohol as a water-soluble polymer. A solution obtained by mixing liquid A and liquid B at a weight ratio of 6.5:3.5 was used as a coating agent for a gas barrier coating film.
The above transparent vapor deposited layer 142 was coated with the gas barrier coating agent prepared above using a spin coating method.
Thereafter, heat treatment was performed in an oven at 180° C. for 60 seconds to form a gas barrier coating film 143 with a thickness of about 400 nm on the transparent vapor deposition layer 142. In this way, a vapor deposited film 14 having a stretched plastic film 141, a transparent vapor deposited layer 142, and a gas barrier coating film 143 was obtained.

[Example A2]
A transparent vapor deposited layer 142 was formed on the stretched plastic film 141 in the same manner as in Example A1, except that the thickness of the transparent vapor deposited layer 142 was 10 nm, and a gas barrier coating film 143 was formed on the transparent vapor deposited layer 142. was formed. In this way, a vapor deposited film 14 having a stretched plastic film 141, a transparent vapor deposited layer 142, and a gas barrier coating film 143 was obtained.

[Example A3]
The transparent vapor deposited layer 142 was formed on the stretched plastic film 141 in the same manner as in Example A1, except that the thickness of the transparent vapor deposited layer 142 was 14 nm, and the gas barrier coating film 143 was formed on the transparent vapor deposited layer 142. was formed. In this way, a vapor deposited film 14 having a stretched plastic film 141, a transparent vapor deposited layer 142, and a gas barrier coating film 143 was obtained.

[Reference example A1]
The transparent vapor deposited layer 142 was formed on the stretched plastic film 141 in the same manner as in Example A1, except that the thickness of the transparent vapor deposited layer 142 was 7 nm, and the gas barrier coating film 143 was formed on the transparent vapor deposited layer 142. was formed. In this way, a vapor deposited film 14 having a stretched plastic film 141, a transparent vapor deposited layer 142, and a gas barrier coating film 143 was obtained.

[Reference example A2]
A transparent vapor deposition layer 142 was formed on the stretched plastic film 141, and a gas barrier coating film 143 was formed on the transparent vapor deposition layer 142 in the same manner as in Example A1, except that the oxygen plasma pretreatment was not performed. . In this way, a vapor deposited film 14 having a stretched plastic film 141, a transparent vapor deposited layer 142, and a gas barrier coating film 143 was obtained.

[Reference example A3]
A transparent vapor deposition layer 142 was formed on a stretched plastic film 141 in the same manner as in Example A1, except that the mixing ratio of oxygen gas and inert gas in the oxygen plasma treatment was oxygen/argon = 4/1. Then, a gas barrier coating film 143 was formed on the transparent vapor deposition layer 142. In this way, a vapor deposited film 14 having a stretched plastic film 141, a transparent vapor deposited layer 142, and a gas barrier coating film 143 was obtained.

[Reference example A4]
A transparent vapor deposition layer 142 was formed on the stretched plastic film 141 in the same manner as in Example A1, except that the pretreatment pressure in the oxygen plasma treatment was 50 Pa, and a gas barrier coating film 143 was formed on the transparent vapor deposition layer 142. was formed. In this way, a vapor deposited film 14 having a stretched plastic film 141, a transparent vapor deposited layer 142, and a gas barrier coating film 143 was obtained.

[Reference example A5]
A transparent vapor deposition layer 142 was formed on the stretched plastic film 141 in the same manner as in Example A1, except that the plasma intensity in the oxygen plasma treatment was 1200 W·sec/m ² , and a gas barrier was formed on the transparent vapor deposition layer 142. A coating film 143 was formed. In this way, a vapor deposited film 14 having a stretched plastic film 141, a transparent vapor deposited layer 142, and a gas barrier coating film 143 was obtained.

The metamorphosis rate was measured for the vapor deposited films 14 of Examples A1 to A3 and Reference Examples A1 to A4 described above. In addition, the color tone was measured for the vapor deposited films 14 of the above-mentioned Example A1 and Reference Example A5. Further, the film laminates including the vapor-deposited films 14 of Examples A1 to A3 and Reference Examples A1 to A2 described above were subjected to oxygen permeability measurements and water vapor permeability measurements.

(metamorphism rate)
Gas barrier coating is applied to the surface of the gas barrier coating film 143 of the vapor-deposited film 14 using time-of-flight secondary ion mass spectrometry (TOF-SIMS) while repeating soft etching at a constant rate with a Cs (cesium) ion gun. Ions originating from the membrane 143, ions originating from the transparent vapor deposition layer 142, and ions originating from the stretched plastic film 141 were measured. As a result, a graph as shown in FIG. 3 described above, in which the unit (intensity) of the vertical axis is the measured ion intensity and the unit (cycle) of the horizontal axis is the number of etchings, was obtained.

The time-of-flight secondary ion mass spectrometer used in TOF-SIMS is ION TOF's TOF. Measurements were performed using SIMS5 under the following measurement conditions.
(TOFSIMS measurement conditions)
・Primary ion type: Bi ₃ ++ (0.2 pA, 100 μs), measurement area: 150 x 150 μm ²
・Et gun type: Cs (1keV, 60nA), Et area: 600 x 600μm ² , Et rate: 3sec/Cycle
In addition, in the analysis, it was necessary to separate ions derived from other components from among the multiple ions derived from aluminum oxide, to select those with sufficient strength, and especially to the concentration distribution of elemental bonds Al ₂ O ₄ H. It is important to obtain a depth distribution that can be approximated. Taking these into consideration, Cs ions were selected as the ion gun for measuring ions derived from aluminum oxide to be measured.

Using Cs, etching was performed from the outermost surface of the gas barrier coating film 143, and analysis of the elemental bonds at the interface between the gas barrier coating film 143, the transparent vapor deposition layer 142, and the stretched plastic film 141 and the elemental bonds of the vapor deposition film was performed. , graphs of the measured elements and elemental bonds were obtained. In the graph, the position where the strength of SiO ₂ (mass number 59.96), which is a constituent element of the gas barrier coating film 143, is half the strength of the gas barrier coating film 143 is defined as the gas barrier coating film 143 and the transparent vapor deposition layer 142. It was identified as the interface of In addition, the position where the strength of C ₆ (mass number 72.00), which is the constituent material of the stretched plastic film 141, is half of the strength in the stretched plastic film 141 is specified as the interface between the stretched plastic film 141 and the transparent vapor deposition layer 142. did. Further, the distance between the two interfaces in the thickness direction was adopted as the thickness of the transparent vapor deposition layer 142.

Next, a peak representing the measured elemental bond Al ₂ O ₄ H (mass number 118.93) was determined, and the region from the peak to the interface was defined as a transition region. However, when the gas barrier coating film 143 is composed of a material having the same mass number as Al ₂ O ₄ H (mass number 118.93), it is necessary to separate the waveform of 118.93.

When the reactant AlSiO 4 and the hydroxide Al 2 O 4 H occur at the interface between the gas barrier coating film 143 and the transparent vapor deposited layer 142, the reactant AlSiO ₄ and the hydroxide Al ₂ O ₄ H occur at the interface between them and the stretched plastic film 141 and the transparent vapor deposited layer 142. The Al ₂ O ₄ H present can be separated off. In this way, the waveform separation can be handled appropriately depending on the material of the gas barrier coating film 143.

In waveform separation, for example, a profile with a mass number of 118.93 obtained by TOF-SIMS is subjected to nonlinear curve fitting using a Gaussian function, and overlapping peaks are separated using a least squares method Levenberg Marquardt algorithm. It can be carried out.

The transformation rate of the transparent vapor deposited layer 142 of the vapor deposited film 14 of Examples A1 to A3 and Reference Examples A1 to A4 was calculated as (thickness W ₁ of the transition region/thickness of the transparent vapor deposited layer 142)×100 (%). The results are shown in FIGS. 8A and 8B.

(Color)
One sample for measurement (stretched plastic film 141/transparent vapor deposited layer 142/gas barrier coating film 143) prepared from vapor deposited film 14 using a spectrophotometer (manufactured by Konica Minolta, Inc. [model name: CM-700d)] ), the L* value, a* value, and b* value in the L*a*b* color system were measured. The results are shown in FIGS. 8A and 8B.

(Oxygen permeability and water vapor permeability)
A 70 μm thick unstretched polypropylene film (CPP film) and a 15 μm thick stretched nylon film were bonded together by a dry lamination method via a two-component curable polyurethane adhesive to produce a laminate. Furthermore, by applying a two-component curing type polyurethane adhesive to the gas barrier coating film 143 side of the vapor-deposited film 14 of Examples A1 to A3 and Reference Examples A1 to A2, and drying the adhesive, the gas barrier coating film 143 was coated with An adhesive layer was formed on the surface. Subsequently, the laminate containing the CPP film and the stretched nylon film and the vapor-deposited film 14 are bonded together via the adhesive layer on the gas barrier coating film 143 of the vapor-deposited film 14 by a dry lamination method to form a film for evaluation. A laminate was produced. The layer structure of the film laminate is expressed as follows from the outside to the inside.
PET film/transparent vapor deposition layer/gas barrier coating film/adhesive layer/stretched nylon film/adhesive layer/CPP film

A sample for measuring oxygen permeability was prepared using a film laminate for evaluation. Specifically, first, the film laminate for evaluation was subjected to an aging treatment at 36° C. for 48 hours, and then the film laminate for evaluation was cut out to prepare a sample.

Subsequently, each of the five types of measurement samples of Examples A1 to A3 and Reference Examples A1 to A2 was set so that the stretched plastic film 141 made of PET film was on the oxygen supply side, and heated at 23° C. and 90% RH. Oxygen permeability was measured in accordance with JIS K 7126 B method under atmospheric measurement conditions. As a measuring device, an oxygen permeability measuring device (manufactured by Modern Control (MOCON) [model name: OX-TRAN 2/21]) was used. The results are shown in FIGS. 8A and 8B.

(water vapor permeability)
Water vapor permeability was measured using the same sample as in the case of oxygen permeability measurement. Specifically, each measurement sample was set so that the stretched plastic film 141 was on the sensor side, and the water vapor permeability was measured in accordance with JIS K 7126 B method under measurement conditions of 40° C. and 100% RH atmosphere. was measured. As a measuring device, a water vapor permeability measuring device (a measuring device manufactured by MOCON [model name: PERMATRAN 3/33]) was used. The results are shown in FIGS. 8A and 8B.

As shown in FIG. 8A, in the vapor deposited films 14 of Examples A1 to A3, the transformation rate of the transition region of the transparent vapor deposited layer 142 is within the above-mentioned range of 5% to 60%, specifically 10%. It was within the range of 25% or more. It was observed that as the thickness of the transparent vapor deposition layer 142 increased, the metamorphism rate tended to decrease. On the other hand, in the vapor deposited films 14 of Reference Examples A1 and A2, the elemental bonding Al ₂ O 4 _H peak was too small to be separated, so the metamorphosis rate in the transition region could not be calculated. Furthermore, in the vapor deposited films 14 of Reference Examples A3 and A4, the plasma discharge was not stable and plasma pretreatment could not be performed, so the metamorphosis rate in the transition region could not be calculated. From these facts, in order to produce the vapor deposited film 14 so that the transformation rate of the transition region of the transparent vapor deposited layer 142 is within the range of 5% to 60%, all of the following manufacturing conditions I to IV must be satisfied. is preferred.
Manufacturing conditions I
The thickness of the transparent vapor deposition layer is 8 nm or more.
Manufacturing conditions II
The mixing ratio of oxygen gas and inert gas in the oxygen plasma treatment is 3/2.5 or more and 3/1 or less.
Manufacturing conditions III
The pretreatment pressure in the oxygen plasma treatment is 1 Pa or more and 20 Pa or less.
Manufacturing conditions IV
The plasma intensity in the oxygen plasma treatment is 100 W·sec/m ² or more and 500 W·sec/m ² or less.

As shown in FIGS. 8A and 8B, the b* value of the vapor deposited film 14 of Reference Example A5 was larger than the b* value of the vapor deposited film 14 of Example A1. Furthermore, in the vapor deposited film 14 of Reference Example A5, it was visually confirmed that the stretched plastic film 141 was colored. The above-mentioned production conditions I to IV are also considered to be useful in suppressing coloring.

As shown in FIG. 8A, in the film laminate including the vapor-deposited films 14 of Examples A1 to A3, the oxygen permeability is 0.5 cc/m ² /24 hr/atm or less, and the water vapor permeability is 0.4 g/m ² /24hr or less. On the other hand, as shown in FIG. 8B, in the sample of the film laminate including the vapor-deposited film 14 of Reference Example A2, the oxygen permeability is 0.8 cc/m ² /24 hr/atm, and the water vapor permeability is 1.1 g/m It was over ² /24hr. From these facts, it can be said that performing oxygen plasma pretreatment is effective in maintaining barrier properties against gases such as oxygen and water vapor.

[Example B1]
As the vapor deposited film 14, the vapor deposited film 14 produced as in Example A1 was prepared.

Further, as the inner thermoplastic resin layer 16, a polyethylene film with a thickness of 60 μm was prepared. Subsequently, the surface of the vapor-deposited film 14 on the gas barrier coating film 143 side and the polyethylene film were laminated with the adhesive layer 15 interposed therebetween by dry lamination. As a result, a first laminate 20 shown in FIG. 5 was obtained.

Further, as the paper base layer 12, base paper for liquids (basis weight: 385 g/m ² ) was prepared. Subsequently, after forming an anchor coat layer on the inner surface of the base paper for liquids, the base paper for liquids and the first laminate 20 are bonded together by the sand lamination method using the above-described laminating apparatus 90 shown in FIG. They were laminated with a resin layer 13 in between. Specifically, the molten adhesive resin constituting the adhesive resin layer 13 was extruded between the liquid base paper and the stretched plastic film 141 of the first laminate 20 at a temperature of 320° C. and a thickness of 20 μm. As the adhesive resin, an ethylene-methacrylic acid copolymer (AN4228C manufactured by DuPont Mitsui Polychemicals Co., Ltd.) was used.

Subsequently, an anchor coat layer was formed on the outer surface of the liquid base paper, and then the molten polyethylene resin was extruded to form the outer thermoplastic resin layer 11. In this way, the packaging material 10 for paper containers shown in FIG. 1 was obtained.

The layer structure of the paper container packaging material 10 of this example is expressed as follows.
PE25/AC/paper/AC/EMAA20/PET12/evaporation/barrier/DL/PEF60
"PE" means an extruded polyethylene layer. "AC" means anchor coat layer. "Paper" means a paper base layer. "EMAA" means an adhesive resin layer made of ethylene-acrylic acid copolymer. "PET" means PET film. "Deposited" means an aluminum oxide film. "Barrier" means a gas barrier coating film. "DL" means adhesive layer. "PEF" means polyethylene film. The numbers refer to the layer thicknesses in μm.

[Example B2]
The same procedure as in Example B1 was carried out, except that the adhesive resin layer 13 was formed by extruding an ethylene-methacrylic acid copolymer (AN4228C manufactured by DuPont Mitsui Polychemical Co., Ltd.) at a temperature of 320° C. and a thickness of 35 μm. A packaging material 10 for paper containers was produced.

The layer structure of the paper container packaging material 10 of this example is expressed as follows.
PE25/AC/paper/AC/EMAA35/PET12/evaporation/barrier/DL/PEF60

[Example B3]
Example B1 except that the adhesive resin layer 13 was formed by extruding an adhesive resin containing a silane group into polyethylene having a density of 0.919 g/cm ³ and an MFR of 8.0 g/10 minutes at a temperature of 320° C. and a thickness of 20 μm. A packaging material 10 for paper containers was produced in the same manner as in the case of Example 1.

The layer structure of the paper container packaging material 10 of this example is expressed as follows.
PE25/AC/paper/AC/silane PE20/PET12/evaporation/barrier/DL/PEF60
"Silane PE" means a polyethylene layer containing silane groups formed by extrusion.

[Example B4]
Example except that the adhesive resin layer 13 was formed by extruding an adhesive resin containing a silane group into polyethylene having a density of 0.919 g/cm ³ and an MFR of 8.0 g/10 minutes at a temperature of 320° C. and a thickness of 35 μm. Packaging material 10 for paper containers was produced in the same manner as in the case of B3.

The layer structure of the paper container packaging material 10 of this example is expressed as follows.
PE25/AC/paper/AC/silane PE35/PET12/evaporation/barrier/DL/PEF60

[Comparative example B1]
The thickness of the polyethylene film of the inner thermoplastic resin layer 16 was 40 μm, and the vapor-deposited film 14 and the polyethylene film of the inner thermoplastic resin layer 16 were bonded by a sand lamination method using extruded polyethylene with a thickness of 20 μm. Except for this, the first laminate 20 was produced in the same manner as in Example B1. In addition, the same procedure as in Example B1 was carried out, except that the adhesive resin layer 13 was formed by extruding an ethylene-acrylic acid copolymer (AN4228C manufactured by DuPont Mitsui Polychemical Co., Ltd.) at a temperature of 320° C. and a thickness of 10 μm. Then, the paper base layer 12 and the vapor deposited film 14 were laminated. Further, in the same manner as in Example B1, the outer thermoplastic resin layer 11 was formed on the outer surface of the paper base layer 12 to obtain the packaging material 10 for paper containers.

The layer structure of the paper container packaging material 10 of this comparative example is expressed as follows.
PE25/AC/paper/AC/EMAA10/PET12/evaporation/barrier/AC/PE20/PEF40

[Comparative example B2]
The same procedure as in Comparative Example B1 was carried out, except that the adhesive resin layer 13 was formed by extruding an ethylene-acrylic acid copolymer (AN4228C manufactured by DuPont Mitsui Polychemical Co., Ltd.) at a temperature of 320° C. and a thickness of 20 μm. A packaging material 10 for paper containers was produced.

The layer structure of the paper container packaging material 10 of this comparative example is expressed as follows.
PE25/AC/paper/AC/EMAA20/PET12/evaporation/barrier/AC/PE20/PEF40

[Comparative example B3]
Packaging material 10 for paper containers was produced in the same manner as in Comparative Example B1, except that adhesive resin layer 13 was formed by extruding low-density polyethylene LC520 manufactured by Japan Polyethylene Co., Ltd. at a temperature of 320 ° C. and a thickness of 20 μm. did.

The layer structure of the paper container packaging material 10 of this comparative example is expressed as follows.
PE25/AC/paper/AC/PE20/PET12/evaporation/barrier/AC/PE20/PEF40

[Comparative example B4]
Paper was prepared in the same manner as in Example B1, except that the adhesive resin layer 13 was formed by extruding an ethylene-acrylic acid copolymer (AN4228C manufactured by DuPont Mitsui Polychemical Co., Ltd.) at a temperature of 320° C. and a thickness of 60 μm. A container packaging material 10 was produced.

The layer structure of the paper container packaging material 10 of this comparative example is expressed as follows.
PE25/AC/paper/AC/EMAA60/PET12/evaporation/barrier/DL/PEF60

The layer configurations of the paper container packaging materials 10 of Examples B1 to B4 and Comparative Examples B1 to B4 are collectively shown in FIG.

The paper container packaging materials 10 of Examples B1 to B4 and Comparative Examples B1 to B4 were subjected to peel strength measurements, water vapor permeability measurements, oxygen permeability measurements, and filling machine sealability evaluations. .

(Peel strength)
The interlayer peel strength (N/15 mm) between the adhesive resin layer 13 and the vapor-deposited film 14 was measured for each of the paper container packaging materials 10 of Examples B1 to B4 and Comparative Examples B1 to B4. Specifically, a 90° peel test was performed at a peel rate of 50 mm/min using a tensile tester (Tensilon Universal Tester RTC1310A, manufactured by Orientech Co., Ltd.). The results are shown in FIG.

(water vapor permeability)
Each of the paper container packaging materials 10 of Examples B1 to B4 and Comparative Examples B1 to B4 was measured using a measuring device manufactured by MOCON (USA) [model name: PERMATRAN] under conditions of a temperature of 40° C. and a humidity of 100% RH. ], water vapor permeability was measured in accordance with JIS K 7129 (number of samples N = 10). The results are shown in FIG.

(Oxygen permeability)
Each of the paper container packaging materials 10 of Examples B1 to B4 and Comparative Examples B1 to B4 was measured using a measuring device manufactured by MOCON (USA) [Model name: OXTRAN] under conditions of a temperature of 23° C. and a humidity of 90% RH. ], the oxygen permeability was measured in accordance with JIS K 7126 (number of samples N=10). The results are shown in FIG.

(Filling machine sealability)
Liquid paper containers were produced by molding and heat sealing each of the paper container packaging materials 10 of Examples B1 to B4 and Comparative Examples B1 to B4. The heat sealing temperature was 260°C, 280°C, 300°C, 320°C or 340°C. In addition, the obtained liquid paper container was filled with water, and it was evaluated whether or not water leaked. In addition, it was visually confirmed whether or not pinholes were generated at the heat-sealed area. The results are shown in FIG. In FIG. 11, "good" means that no water leakage occurred and no pinholes were generated at the heat-sealed location. Moreover, "not good" means that no water leakage occurred, but a pinhole occurred at the heat-sealed location. Moreover, "bad" means that delamination occurred in the packaging material 10 for paper containers when the packaging material 10 for paper containers was molded and heat-sealed.

As can be seen from the comparison between Examples B1 to B4 and Comparative Example B3, by using an ethylene-acrylic acid copolymer or a silane group-containing compound as the adhesive resin layer 13, it was possible to ensure peel strength. Specifically, the peel strength was able to be 2.8 N/15 mm or more.

As can be seen from the comparison between Examples B1 to B4 and Comparative Examples B1 to B3, by adhering the vapor deposited film 14 and the inner thermoplastic resin layer 16 by dry lamination rather than sand lamination, water vapor barrier properties and oxygen barrier properties are improved. I was able to secure sex. Specifically, the water vapor permeability and oxygen permeability were able to be reduced to 1 cc/m ² ·day or less. Further, as can be seen from the comparison between Examples B1 to B4 and Comparative Example B4, by setting the thickness of the adhesive resin layer 13 to 35 μm or less, water vapor barrier properties and oxygen barrier properties were able to be ensured.

As can be seen from the comparison between Examples B1 and B2 and Comparative Example B1, by setting the thickness of the adhesive resin layer 13 made of ethylene-acrylic acid copolymer to 20 μm or more, the formation of pinholes at the heat-sealed area was suppressed. We were able to.

10 Packaging material for paper containers 11 Outer thermoplastic resin layer 12 Paper base layer 13 Adhesive resin layer 14 Vapor deposited film 141 Stretched plastic film 142 Transparent vapor deposited layer 143 Gas barrier coating film 15 Adhesive layer 16 Inner thermoplastic resin layer 161 First Layer 162 Second layer 163 Third layer 20 Laminated body 90 Lamination device 91 First supply roll 92 Second supply roll 100 Liquid paper container

Claims (5)

A packaging material for a paper container comprising, in order from the outside to the inside, at least an outer thermoplastic resin layer, a paper base layer, an adhesive resin layer, a vapor-deposited film, an adhesive layer, and an inner thermoplastic resin layer,
The vapor-deposited film includes a stretched plastic film, a transparent vapor-deposited layer containing aluminum oxide and provided on the inner surface of the stretched plastic film, and a gas barrier coating film provided on the transparent vapor-deposited layer. have,
The stretched plastic film of the vapor-deposited film contains biomass-derived polyester,
The adhesive resin layer is a resin composition containing one or more compounds selected from the group consisting of an epoxy group-containing compound, a silane group-containing compound, a carboxylic acid group-containing compound, and an acid anhydride-containing compound. ,
The thickness of the adhesive resin layer is 15 μm or more and 40 μm or less,
The adhesive layer includes a cured product of a polyol and an isocyanate compound,
The transparent deposited layer includes a transition region,
The transition region is an elemental bond that transforms into aluminum hydroxide, which is detected by etching the deposited film from the gas barrier coating side using time-of-flight secondary ion mass spectrometry (TOF-SIMS). a region between the peak position of Al ₂ O ₄ H and the interface between the transparent vapor deposition layer and the stretched plastic film,
A packaging material for paper containers, wherein the ratio of the thickness of the transition region to the thickness of the transparent vapor deposition layer is 5% or more and 60% or less. The paper container packaging material according to claim 1 , wherein the gas barrier coating film of the vapor-deposited film is in contact with the adhesive layer. The paper container packaging material according to claim 1 or 2 , wherein the adhesive resin layer is in contact with an outer surface of the stretched plastic film. The packaging material for a paper container according to any one of claims 1 to 3 , wherein the outer thermoplastic resin layer or the inner thermoplastic resin layer contains biomass-derived polyethylene. A liquid paper container comprising the paper container packaging material according to any one of claims 1 to 4 .