JP2021035753A - Paper laminate and method for producing the same - Google Patents

Abstract

To provide a paper laminate having excellent processing durability and has high barrier performance.SOLUTION: A paper laminate has a resin layer on at least one face of a paper substrate, and has a vapor deposition layer composed of metal or ceramic of 1 to 1000 nm in thickness on the resin layer, the resin layer containing a water-suspendible polymer and a tabular inorganic compound with an aspect ratio of 80 or more. The paper substrate preferably has a basis weight of 20 to 500 g/m2. The vapor deposition layer is preferably composed of aluminum, silicon oxide or aluminum oxide.SELECTED DRAWING: None

Description

The present invention relates to a paper laminate.

Packaging materials that have water vapor barrier properties and gas barrier properties (particularly oxygen barrier properties) added to the paper base material have been conventionally used in packaging foods, medical products, electronic parts, etc. in order to prevent deterioration of the quality of the contents. Has been done.

As a method for imparting water vapor barrier property or gas barrier property to the paper base material, a method of laminating a synthetic resin film having excellent gas barrier property on the paper base material is common. However, it is difficult to recycle paper, synthetic resin, etc. after use of a material in which a synthetic resin film or the like is laminated on a paper base material, which poses an environmental problem.

Therefore, the development of a gas barrier material based on paper has been promoted without using a synthetic resin film or the like. For example, Patent Document 1 proposes a paper barrier material in which a water vapor barrier layer and a gas barrier layer are provided in this order on a paper base material. The water vapor barrier layer contains a water vapor barrier resin and a water repellent, and the gas barrier layer contains a water-soluble polymer and a surfactant. Further, Patent Document 2 proposes a paper barrier packaging material in which a water vapor barrier layer and a gas barrier layer are provided on a paper base material. The water vapor barrier layer contains 50 to 100% by weight of kaolin having an average particle size of 5 μm or more and an aspect ratio of 10 or more with respect to all pigments, and the binder resin of the gas barrier layer is a polyvinyl alcohol resin.

Japanese Patent No. 6234654 Japanese Patent No. 5331265

Although attempts have been made to improve the oxygen barrier property and the water vapor barrier property of the paper substrate as in Patent Documents 1 and 2, sufficient barrier performance has not been obtained. In addition, since the barrier layer is destroyed by deformation, durability during use or processing becomes a problem. That is, when three-dimensional processing such as embossing or bending processing is performed, there is a problem that the barrier performance is deteriorated probably because the barrier layer is damaged such as cracks.
Therefore, an object of the present invention is to provide a paper laminate having excellent durability against processing and high barrier performance.

As a result of diligent studies, the present inventors provided a resin layer and a metal or ceramic vapor deposition layer having a specific thickness in this order on a paper base material, and the resin layer has a water-suspendable polymer and a predetermined aspect ratio. It has been found that a laminate containing a plate-like inorganic compound solves the above-mentioned problems.
That is, the present invention relates to the following <1> to <9>.
<1> A resin layer is provided on at least one surface of a paper base material, a vapor-deposited layer made of a metal or ceramic having a thickness of 1 to 1000 nm is provided on the resin layer, and the resin layer is a water-suspendable polymer and A paper laminate characterized by containing a plate-like inorganic compound having an aspect ratio of 80 or more.
<2> The paper laminate according to <1>, wherein the basis weight of the paper base material is 20 to 500 g / m ^2. <3> The paper laminate according to <1> or <2>, wherein the vapor-deposited layer is made of aluminum, silicon oxide, or aluminum oxide.
<4> The water-suspendable polymer in the resin layer is selected from the group consisting of an olefin / unsaturated carboxylic acid-based copolymer, a styrene / butadiene-based copolymer, and a styrene / acrylic-based copolymer. The paper laminate according to any one of <1> to <3>, which is more than a seed.
<5> The paper laminate according to any one of <1> to <4>, wherein the plate-like inorganic compound in the resin layer is at least one selected from the group consisting of synthetic mica, bentonite, and kaolin. body.
<6> The paper laminate according to any one of <1> to <5>, wherein the resin layer contains a plate-like inorganic compound in an amount of 0.1% by mass or more and 70% by mass or less.
<7> The paper laminate according to any one of <1> to <6>, wherein the resin layer contains a cationic resin.
<8> The paper laminate according to any one of <1> to <7>, which further has a sealant layer on the vapor-deposited layer.
<9> The paper laminate according to any one of <1> to <8>, which further has a second resin layer between the resin layer and the thin-film deposition layer.
<10> The paper laminate according to any one of <1> to <9>, which is a packaging material.
<11> A step of applying a resin layer paint to at least one surface of a paper base material and drying it to form a resin layer containing a water-suspendable polymer and a plate-like inorganic compound having an aspect ratio of 80 or more. A method for producing a paper laminate, which comprises a step of providing an aluminum vapor deposition layer on the resin layer.
<12> The method for producing a paper laminate according to <11>, which comprises a step of further providing a second resin layer on the resin layer as a pre-process of a step of providing an aluminum vapor deposition layer on the resin layer.

According to the present invention, it is possible to provide a paper laminate having excellent durability against processing and high barrier performance.

[Paper laminate]
The paper laminate of the present invention has a resin layer on at least one surface of a paper base material, has a vapor-deposited layer made of a metal or ceramic having a thickness of 1 to 1000 nm on the resin layer, and the resin layer is water-suspended. It contains a turbid polymer and a plate-like inorganic compound having an aspect ratio of 80 or more.
The paper laminate of the present invention has a high gas barrier property (particularly oxygen barrier property) and a water vapor barrier property by having a thin-film deposition layer, and by having a resin layer, the vapor-deposited layer is protected even by deformation of the paper during processing. And the barrier property can be maintained. In addition, the vapor-deposited layer having a glossy feeling is excellent in designability.

The paper substrate may have a resin layer and a thin-film deposition layer on one side, or may have a resin layer and a thin-film deposition layer on both sides. However, from the viewpoint of production efficiency, the resin layer and the thin-film deposition layer may be provided on one side. It is preferable to have. In the present invention, even if the resin layer and the vapor-deposited layer are provided on only one side, sufficient barrier properties can be exhibited.
The vapor deposition layer is preferably formed directly on the resin layer. Since the vapor-deposited layer is formed directly on the resin layer, the resin layer can efficiently protect the vapor-deposited layer from being damaged due to deformation of the paper during processing.

<Paper base material>
The paper base material used in the paper laminate of the present invention is preferably a commonly used paper containing plant-derived pulp as a main component, and more preferably a paper containing wood pulp as a main component. preferable. Further, it is preferable that the paper contains pulp as a main component, which is easily dispersed in water by a mechanical dissociation action.
Specific examples include bleached kraft paper, unbleached kraft paper, high-quality paper, paperboard, liner paper, coated paper, single-gloss paper, glassin paper, graphan paper, etc. Among these, bleached kraft paper and unbleached paper. Kraft paper, high-quality paper, and single-gloss paper are preferable.

The dissociation freeness (degree of drainage) measured according to JIS P8121: 2012 of the paper base material is preferably 800 ml or less, more preferably 500 ml or less, from the viewpoint of improving the barrier property. Here, the dissociation freeness is a Canadian standard drainage degree obtained by measuring pulp obtained by dissociating the paper after papermaking in accordance with JIS P82201 in accordance with JIS P8121: 2012. .. As a method for beating the pulp to adjust the disintegration freeness, a known method can be used.

The size of the paper base material is not particularly limited, but from the viewpoint of improving the barrier property, it is preferable that the size of the stechhito according to JIS P8122: 2004 is 1 second or more. The size of the paper substrate can be controlled by the type and content of the internal sizing agent, the type of pulp, the smoothing treatment, and the like.
Examples of the internal sizing agent include rosin type, alkyl ketene dimer type, alkenyl succinic anhydride type, styrene-acrylic type, higher fatty acid type, petroleum resin type and the like. The content of the internal sizing agent is preferably 3 parts by mass or less with respect to 100 parts by mass of the pulp of the paper base material.

In addition to the internal sizing agent, other known internal additives may be added to the paper substrate. Internal additives include fillers, paper strength enhancers, yield improvers, pH adjusters, drainage improvers, water resistant agents, fabric softeners, antistatic agents, defoamers, slime control agents, dyes / pigments, etc. Can be mentioned.
Examples of the filler include titanium dioxide, kaolin, talc, calcium carbonate and the like.

For paper making of a paper base material, a known wet paper machine can be appropriately selected and used.
Examples of the paper machine include a long net paper machine, a gap former type paper machine, a circular net type paper machine, and a short net type paper machine.
The paper layer formed by the paper machine is preferably conveyed by, for example, felt and dried by a dryer. A multi-stage cylinder dryer may be used as a pre-dryer before drying the dryer.

Further, the paper base material obtained as described above may be surface-treated with a calendar to make the thickness and profile uniform. As the calendar processing, a known calendar processing machine can be appropriately selected and used. Calendering can also be performed after the resin layer has been formed.

The basis weight of the paper substrate is preferably 20 to 500 g / ^{m 2,} more preferably 20 to 400 g / ^{m 2,} more preferably 20 to 200 g / ^{m 2,} even more preferably from 30 to 100 g / ^{m 2} ..
The paper substrate, from the viewpoint of moldability, it is preferable that a density of ^{0.5~1.2g / cm 3, 0.6~1.0g / cm} 3 is more preferable.
From the viewpoint of obtaining a uniform thin-film deposition layer, the paper substrate preferably has a Wangken-type smoothness of 5 seconds or more, more preferably 10 to 1000 seconds. From the viewpoint of printability, the paper base material preferably has a 75 ° glossiness of 5% or more, more preferably 10 to 70%.

<Thin-film deposition layer>
The vapor-deposited layer used in the paper laminate of the present invention is made of a metal or ceramic having a thickness of 1 to 1000 nm.
The thickness of the thin-film deposition layer is 1 to 1000 nm, preferably 2 to 500 nm, more preferably 3 to 100 nm, further preferably 4 to 50 nm, and even more preferably 5 to 30 nm.

The vapor deposition layer is made of metal or ceramic, preferably metal.
When the vapor-deposited layer is a metal, specific examples thereof include aluminum and titanium, and aluminum is preferable.
When the vapor-deposited layer is ceramic, specific examples thereof include silicon oxide, titanium oxide and aluminum oxide, and silicon oxide or aluminum oxide is preferable.
That is, the vapor-deposited layer is more preferably made of aluminum, silicon oxide or aluminum oxide, and aluminum is even more preferable.

<Resin layer>
The resin layer in the present invention contains a water-suspendable polymer and a plate-like inorganic compound having an aspect ratio of 80 or more. As a result, when a microscopic magnified photograph of the resin layer is taken, a dense film having no voids is formed, which is clearly different from the conventional one. The dense film structure of this resin layer without voids exhibits excellent water vapor barrier properties. In addition, it contributes to the formation of a uniform thin-film deposition layer and exhibits excellent oxygen barrier properties and water vapor barrier properties. In addition, since the resin layer has high barrier properties as well as flexibility, there is little deterioration in barrier properties during processing.

(Water-suspendable polymer)
The water-suspendable polymer is a polymer that can be suspended in water, and it is easy to prepare a coating liquid using water as a dispersion medium when forming a resin layer on a paper substrate. To. Since the water-suspendable polymer functions as a binder in the formation of the resin layer, a resin layer containing a plate-like inorganic compound or the like can be formed on the paper substrate.
The water-suspendable polymer is preferably a thermoplastic resin from the viewpoint of giving flexibility to the resin layer and enhancing durability during processing, and is an olefin / unsaturated carboxylic acid-based copolymer and a styrene / butadiene-based copolymer. , And one or more selected from the group consisting of styrene / acrylic copolymers.

(Olefin / unsaturated carboxylic acid copolymer)
The olefin / unsaturated carboxylic acid-based copolymer is a copolymer obtained by emulsion polymerization of an olefin monomer and an unsaturated carboxylic acid-based monomer.
Examples of the olefin monomer of the olefin / unsaturated carboxylic acid-based copolymer include ethylene and α-olefins such as propylene and butylene, and among these, ethylene is preferable.
The unsaturated carboxylic acid-based monomer of the olefin / unsaturated carboxylic acid-based copolymer includes an unsaturated carboxylic acid monomer and an ester monomer of an unsaturated carboxylic acid that forms a carboxylic acid by hydrolysis. Examples of the unsaturated carboxylic acid-based monomer of the olefin / unsaturated carboxylic acid-based copolymer include acrylic acid, methacrylic acid, crotonic acid, silicic acid, itaconic acid, fumaric acid, maleic acid, and butentricarboxylic acid. Unsaturated carboxylic acids and esters thereof; examples include unsaturated polycarboxylic acid alkyl esters having at least one carboxy group, such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, maleic acid monobutyl ester.
The unsaturated carboxylic acid-based monomer constituting the olefin / unsaturated carboxylic acid-based copolymer may be used alone or in combination of two or more. The olefin / unsaturated carboxylic acid-based copolymer may be copolymerized with a small amount of an olefin and other monomers copolymerizable with the unsaturated carboxylic acid-based monomer.
Among these, the olefin / unsaturated carboxylic acid-based copolymer is preferably one or more selected from the group consisting of ethylene / acrylic acid-based copolymers and ethylene / methacrylic acid-based copolymers, and ethylene. -Acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / methyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / ethyl methacrylate copolymer , Ethylene / butyl acrylate copolymer, and one or more selected from the group consisting of ethylene / butyl methacrylate copolymer, and more preferably ethylene / acrylate copolymer.

The content of the unsaturated carboxylic acid-based monomer unit of the olefin / unsaturated carboxylic acid-based copolymer is preferably 1 mol% or more, more preferably 10 mol% or more, and preferably 50 mol% or less. It is preferably 30 mol% or less. When the content of the unsaturated carboxylic acid-based monomer is within the above range, the dispersibility of the plate-like inorganic compound is excellent.

The weight average molecular weight of the olefin / unsaturated carboxylic acid-based copolymer is preferably 10,000 or more, more preferably 20,000 or more, and preferably 20,000 or more, from the viewpoint of viscosity and strength when applied to a paper substrate. It is 10 million or less, more preferably 5 million or less.

A commercially available product may be used as the olefin / unsaturated carboxylic acid-based copolymer, and examples thereof include "Zyxene (trade name)" manufactured by Sumitomo Seika Chemical Co., Ltd.

(Styrene-butadiene copolymer)
Examples of the styrene-butadiene copolymer include styrene-butadiene rubber (SBR) and modified styrene-butadiene rubber (modified SBR).
Examples of the modified styrene-butadiene rubber include acid-modified styrene-butadiene rubber (acid-modified SBR).
Commercially available products may be used as the styrene-butadiene copolymer, and examples thereof include "Nipol LX407S series (trade name)" and "Nipol LX407BP series (trade name)" manufactured by Zeon Corporation.

(Styrene / acrylic copolymer)
The styrene / acrylic copolymer includes aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene, and acrylic acid, methacrylic acid, crotonic acid, silicic acid, and ester. Unsaturated carboxylic acids such as acids, fumaric acids, maleic acids and butentricarboxylic acids, unsaturated polycarboxylic acids with at least one carboxyl group such as itaconic acid monoethyl esters, fumaric acid monobutyl esters and maleic acid monobutyl esters. An unsaturated sulfonic acid monomer such as an alkyl ester, an acrylamide propane sulfonic acid, a sulfoethyl sodium acrylate salt, a sodium sulfopropyl methacrylate salt, or a salt thereof, and a monomer composed of other compounds copolymerizable therewith. It is a copolymer obtained by emulsification polymerization. Styrene and the like are suitable as the aromatic vinyl compound, and acrylic acid, methacrylic acid, itaconic acid, fumaric acid and the like are suitable as the unsaturated carboxylic acid monomer, the unsaturated sulfonic acid monomer or a salt thereof. ..

(Plate-shaped inorganic compound)
The plate-like inorganic compound has an aspect ratio of 80 or more, preferably 100 or more, more preferably 200 or more, still more preferably 300 or more, and particularly preferably 500 or more. The larger the aspect ratio, the longer the moving distance of water vapor and gas becomes. Due to the maze effect, the water vapor barrier property and the gas barrier property can be improved. Further, the larger the aspect ratio, the more the amount of the plate-like inorganic compound added can be reduced. The upper limit of the aspect ratio is not particularly limited, but is preferably 10,000 or less from the viewpoint of availability, viscosity when forming the resin layer on the paper substrate, and the like.
The aspect ratio of the plate-like inorganic compound is such that at least 30 plates are taken by taking an enlarged photograph using an electron microscope for a cross section in a thickness direction (vertical direction of the resin layer) parallel to the direction in which the resin layer is applied. The average length and average thickness are obtained by measuring the length and thickness of the state-inorganic compound and performing arithmetic averaging. Then, the value obtained by dividing the average length of the plate-shaped inorganic compound by the average thickness is defined as the aspect ratio of the plate-shaped inorganic compound.

The plate-like inorganic compound is not particularly limited as long as it has the above aspect ratio, but is preferably one or more selected from the group consisting of synthetic mica, bentonite, and kaolin, and more preferably synthetic mica. And one or more selected from the group consisting of kaolin.

The thickness (average thickness) of the plate-shaped inorganic compound is preferably 300 nm or less, more preferably 200 nm or less, and further preferably 120 nm or less. When the average thickness of the plate-shaped inorganic compound is small, the number of laminated plate-shaped inorganic compounds in the resin layer is large, so that a high water vapor barrier property can be exhibited.

The length (average length) of the plate-shaped inorganic compound is preferably 1 μm to 100 μm. When the length is 1 μm or more, the plate-like inorganic compound tends to be arranged parallel to the paper substrate. Further, when the length is 100 μm or less, there is little concern that a part of the plate-like inorganic compound protrudes from the water vapor barrier layer.

From the viewpoint of improving the water vapor barrier property and the gas barrier property, the resin layer preferably contains a plate-like inorganic compound in an amount of 0.1% by mass or more, more preferably 1.0% by mass or more, based on the total solid content of the resin layer. It is more preferably 2.0% by mass or more, and from the viewpoint of improving the smoothness of the surface of the layer to be vapor-deposited, it is preferably 70% by mass or less, more preferably 40% by mass, still more preferably 30% by mass or less. Particularly preferably, it is contained in an amount of 20% by mass or less. From the viewpoint of being effective with a smaller content, synthetic mica having a large aspect ratio and a small thickness can be preferably used among the plate-like inorganic compounds.

(Cationic resin)
The resin layer preferably contains a cationic resin. As a result, the dispersibility of the plate-like inorganic compound is improved, and the water vapor barrier property is greatly improved. The plate-shaped inorganic compound has a so-called card house structure in which the plate-shaped inorganic compounds are three-dimensionally connected to each other because the plate-shaped flat portion is easily charged anionic and the edge portion is easily charged cationically. It has been known. Due to this card house structure, the viscosity of the aqueous dispersion of the plate-like inorganic compound becomes very high. On the other hand, since the card house structure is easily broken when a force is applied by stirring or the like, the aqueous dispersion of the plate-like inorganic compound exhibits thixotropy. It is considered that when an appropriate cationic resin is added to the aqueous dispersion of the plate-shaped inorganic compound, the card house structure is destroyed by adsorbing the cationic resin on the anionically charged flat portion of the plate-shaped inorganic compound. Be done. As a result, it is presumed that the three-dimensional connection of the plate-shaped inorganic compounds is suppressed, the plate-shaped inorganic compounds are easily laminated in parallel with the plane of the paper substrate, and the water vapor barrier property is improved. Furthermore, it is estimated that the gas barrier property is also improved.

Cationic resins include polyamine resins, cation-modified polyamide resins (eg amine-modified polyamide resins), polyamide epichlorohydrin resins, polyethyleneimine resins, polyalkylene polyamine resins, polyamide compounds, polyamideamine epihalohydrins or formaldehyde condensation reaction formation. , Polyamine / epihalohydrin or formaldehyde condensation reaction product, polyamide polyurea / epihalohydrin or formaldehyde condensation reaction product, polyamine polyurea / epihalohydrin or formaldehyde condensation reaction product, polyamideamine polyurea / epihalohydrin or formaldehyde condensation reaction product, polyamide Examples thereof include polyurea compounds, polyamine polyurea compounds, polyamideamine polyurea compounds and polyamideamine compounds, polyvinylpyridines, amino-modified acrylamide compounds, polyvinylamine resins, and polydiallyldimethylammonium chlorides.
Among these, the cationic resin is preferably at least one selected from a polyamine resin, a cationically modified polyamide resin, and a polyethyleneimine resin, and more preferably a cationically modified polyamide resin.

The content of the cationic resin in the resin layer is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the water-suspendable polymer, from the viewpoint of improving the water vapor barrier property. It is more preferably 3 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass, still more preferably 10 parts by mass.

In addition to the water-suspendable polymer, the plate-like inorganic compound, and the cationic resin, the resin layer contains a dispersant, a surfactant, a defoaming agent, and a wetting agent other than the above-mentioned cationic resin, as needed. , Dyes, tint adjusters, thickeners, water-soluble polymers and the like can be added.

<Second resin layer>
In the present invention, it is preferable to further have a second resin layer between the resin layer and the vapor-deposited layer. The second resin layer contains a water-soluble polymer. As a result, the gas barrier property, particularly the oxygen barrier property, is excellent. Further, the resin layer can be protected to improve the bending suitability, and the thin-film deposition layer can be uniformly formed to improve the barrier property.

(Water-soluble polymer)
Examples of the water-soluble polymer include polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, cellulose derivatives, polyvinylpyrrolidone, urethane resins, polyacrylic acid and salts thereof, casein, polyethyleneimine and the like.

Among these, completely saponified or partially saponified polyvinyl alcohol or modified polyvinyl alcohol is preferable because it has more excellent gas barrier properties. Examples of the modified polyvinyl alcohol include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol.

The content of the water-soluble polymer is preferably 50 to 100% by mass, more preferably 50 to 90% by mass, and 60 to 80% by mass, based on the total solid content of the second resin layer. Is even more preferable.

Similar to the resin layer, the second resin layer may contain the above-mentioned plate-like inorganic compound. The plate-like inorganic compound is preferably at least one selected from the group consisting of synthetic mica, bentonite and kaolin from the viewpoint of improving the barrier property. The plate-shaped inorganic compound contained in the second resin layer may be of the same type as the plate-shaped inorganic compound contained in the resin layer, or may be of a different type. When the plate-shaped inorganic compound is contained in the second resin layer, the content of the plate-shaped inorganic compound is not particularly limited, but is 1 to 80 mass by mass with respect to 100 parts by mass of the water-soluble polymer of the second resin layer. About 5 to 70 parts by mass is preferable. Among the plate-like inorganic compounds, it is preferable to contain about 5 to 15 parts by mass of synthetic mica having a large aspect ratio and a small thickness with respect to 100 parts by mass of the water-soluble polymer of the second resin layer.

In addition to the water-soluble polymer, the second resin layer is appropriately composed of a plate-like inorganic compound, other pigments, the above-mentioned cationic resin, a dispersant other than the above-mentioned cationic resin, a surfactant, and a defoamer. Auxiliary agents such as foaming agents, wetting agents, dyes, tint adjusters, and thickeners can be added.

<Sealant layer>
In the present invention, it is preferable to further have a sealant layer on the vapor deposition layer.

The sealant layer is a layer that melts and adheres by heating or ultrasonic waves, and is a layer that can bond the paper laminates to each other by heat sealing or the like.

The sealant layer can be formed by laminating a synthetic resin such as polyethylene, polypropylene, an ethylene-vinyl acetate polymer, or a polyvinyl acetate polymer by a melt extrusion laminating method or a dry laminating method. The sealant layer can also be formed by applying an emulsified dispersion of a synthetic resin such as polyethylene, polypropylene, an ethylene-vinyl acetate polymer, or a polyvinyl acetate polymer.

The sealant layer preferably contains a biodegradable resin. Specific examples of the biodegradable resin are not particularly limited, and for example, polylactic acid (PLA). Polybutylene succinate (PBS) Polybutylene succinate adipate (PBSA), 3-hydroxybutanoic acid / 3-hydroxyhexanoic acid copolymer (PHBH) and the like can be mentioned.

The thickness of the sealant layer is preferably 1 to 50 μm, more preferably 3 to 30 μm. The amount of the sealant layer formed is preferably 1 to 50 g / m ² and more preferably 3 to ^{30 g / m 2 as the solid content.}

[Manufacturing method of paper laminate]
In the paper laminate of the present invention, a resin layer, a vapor-deposited layer, and if necessary, a second resin layer and a sealant layer are formed in this order on at least one surface of the paper base material. The method for forming each layer is not particularly limited, but it is preferable that the resin layer and the second resin layer are formed by a coating method. Specifically, it is preferable to apply a resin layer coating liquid (resin layer paint) on a paper base material and dry it to form a resin layer. Further, it is preferable that the second resin layer coating liquid (second resin layer coating material) is applied onto the resin layer and dried to form the second resin layer.

The coating equipment for applying the coating liquid is not particularly limited, and known equipment may be used. Examples of the coating equipment include a blade coater, a bar coater, an air knife coater, a slit die coater, a gravure coater, a micro gravure coater, and a gate roll coater. In particular, for forming the resin layer, a coater that scrapes the coated surface, such as a blade coater, a bar coater, an air knife coater, and a slit die coater, is preferable because it promotes the orientation of the plate-like inorganic compound.

The drying equipment for drying the coating layer is not particularly limited, and known equipment can be used. Examples of the drying equipment include a hot air dryer, an infrared dryer, a gas burner, a hot plate, and the like. Further, the drying temperature may be appropriately set in consideration of the drying time and the like.

The solvent of the coating liquid is not particularly limited, and water or an organic solvent such as ethanol, isopropyl alcohol, methyl ethyl ketone or toluene can be used.
Among these, in the present invention, water is preferable as the dispersion medium of the coating liquid from the viewpoint of not causing the problem of the volatile organic solvent. That is, the resin layer coating liquid is preferably an aqueous composition for the resin layer. Further, the second resin layer coating liquid is also preferably an aqueous composition for the second resin layer.

The solid content of the coating liquid is not particularly limited and may be appropriately selected from the viewpoint of coatability and ease of drying, but is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass. % Or more, and preferably 80% by mass or less, more preferably 70% by mass or less, still more preferably 60% by mass or less.

^{The amount of coating of the resin layer (after drying) is not particularly limited, but is preferably 1 g / m 2} from the viewpoint of obtaining a paper laminate having excellent water vapor barrier property and gas barrier property, water resistance, and excellent economy. As described above, it is more preferably 2 g / m ² or more, further preferably 3 g / m ² or more, and the upper limit thereof is preferably 15 g / m ² or less, more preferably 7 g / m ² or less. The coating amount of the second resin layer (after drying) is not particularly limited, is preferably from 0.1 to 10 g / ^{m 2,} and more preferably 0.5 to 5 g / ^{m 2.}

As a method of depositing metal or ceramic on the resin layer and on the second resin layer provided as needed, the metal or ceramic is vacuum-deposited directly on the surface of the resin layer or the surface of the second resin layer provided as needed. The method of
Examples of the metal or ceramic used here include aluminum, silicon oxide, and aluminum oxide, and aluminum is preferable from the viewpoint of cost and appearance.

The paper laminate of the present embodiment can be suitably used as a packaging material for foods such as coffee, confectionery, milk, pharmaceuticals, medical products, electronic parts, etc. by taking advantage of the above-mentioned excellent water vapor barrier property and gas barrier property. it can. Among these, since it has resistance to cracking, it can be suitably used for flexible packaging materials, paper containers for heavy bags, packaging containers such as milk cartons, and the like.

Hereinafter, the features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed in a limited manner by the specific examples shown below. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples indicate "parts by mass" and "% by mass", respectively.

[Example 1]
<Preparation of resin layer paint>
Aqueous dispersion of plate-like inorganic compound (Engineered Kaolin, "Varisurf HX (trade name)" manufactured by Imeris Minerals Japan Co., Ltd., aspect ratio: about 100, thickness: about 100 nm, solid content: 55%) 50 Ethylene-acrylic acid copolymer (“Zyxen AC (trade name)” manufactured by Sumitomo Seika Co., Ltd., solid content: 29.2%, copolymerization ratio of acrylic acid: 20 mL) in 7 parts with stirring. , Melting point: 80-95 ° C.) 48 parts were added, and the mixture was further stirred. To this, 1.1 parts of a cation-modified polyamide resin (“Sumirez Resin SPI-203 (50) H (trade name)” manufactured by Taoka Chemical Industry Co., Ltd., solid content: 53%) was added and stirred. Further, 0.17 part of a 25% aqueous ammonia solution was added and stirred. Further, water was added and stirred so that the solid content concentration became 20% to prepare a resin layer coating material.
<Manufacturing of paper laminate>
Apply the obtained resin layer paint to bleached kraft paper (basis weight: 50 g / m ² , thickness: 60 μm) using a Mayer bar so that the coating amount of the resin layer after drying is 6 g / m ^2. After coating, it was dried in a hot air dryer at 120 ° C. for 1 minute. Further, an aluminum vapor deposition layer (thickness 20 nm) was provided on the resin layer by vacuum vapor deposition to obtain a paper laminate.

[Example 2]
Seixen AC (above, solid content: 29.2%, manufactured by Sumitomo Seika Chemical Co., Ltd.) was diluted with water to 20% to prepare a sealant layer paint. Using the paper laminate obtained in Example 1, the paint of the sealant layer was applied on the vapor-deposited layer with a Mayer bar (No. 16), and dried in a hot air dryer at 120 ° C. for 1 minute to form the sealant layer. A paper laminate of Example 2 having was obtained.

[Example 3]
Randy PL-3000 (solid content: 40%, made of Miyoshi Oil & Fat) was diluted with water to 20% to prepare a sealant layer paint. Using the paper laminate obtained in Example 1, the paint of the sealant layer was applied on the vapor-deposited layer with a Mayer bar (No. 16), and dried in a hot air dryer at 120 ° C. for 1 minute to form the sealant layer. The paper laminate of Example 3 having was obtained.

[Example 4]
<Preparation of resin layer paint>
Water dispersion of plate-like inorganic compound (synthetic mica, "NTO-05 (trade name)" manufactured by Topy Industries, Ltd., aspect ratio: about 1000, thickness: about 5 nm, solid content: 6%) 19.7 parts While stirring, an ethylene / acrylic acid copolymer (“Zyxen AC (trade name)” manufactured by Sumitomo Seika Co., Ltd., solid content: 29.2%, acrylic acid copolymerization ratio: 20 mL%, melting point: 80-95 ° C.) 34.3 parts was added, and the mixture was further stirred. To this, 1.7 parts of a cation-modified polyamide resin (“Sumirez Resin SPI-203 (50) H (trade name)” manufactured by Taoka Chemical Industry Co., Ltd., solid content 53%) was added and stirred. Further, 0.1 part of a 25% aqueous ammonia solution was added and stirred. Further, water was added and stirred so that the solid content concentration became 20% to prepare a resin layer coating material.
<Manufacturing of paper laminate>
Apply the obtained resin layer paint to bleached kraft paper (basis weight: 50 g / m ² , thickness: 60 μm) using a Mayer bar so that the coating amount of the resin layer after drying is 6 g / m ^2. After coating, it was dried in a hot air dryer at 120 ° C. for 1 minute. Further, an aluminum vapor deposition layer (thickness 20 nm) was provided on the resin layer by vacuum vapor deposition to obtain a paper laminate.
Seixen AC (solid content: 29.2%, manufactured by Sumitomo Seika Chemicals) was diluted with water to 20% to prepare a sealant layer paint. Using the paper laminate obtained in (Example 4) above, the paint of the sealant layer was applied on the vapor-deposited layer with a Mayer bar (No. 16), and dried in a hot air dryer at 120 ° C. for 1 minute. A paper laminate of Example 4 having a sealant layer was obtained.

[Example 5]
<Preparation of second resin layer paint>
An aqueous solution having a solid content concentration of 10% of ethylene-modified polyvinyl alcohol (completely saponified type, product name: Excelval AQ-4104, manufactured by Kuraray Co., Ltd.) was prepared and used as a second resin layer coating material.

<Preparation of paint for sealant layer>
Zyxen AC (above, solid content: 29.2%, manufactured by Sumitomo Seika Chemical Co., Ltd.) was diluted with water to 20% to prepare a paint for a sealant layer.

In the manufacture of paper laminates of Example 1, in place of the coating amount after drying of the resin layer to 6 g / m ² and 12 g / m ^2, the second resin layer coating obtained above on the resin layer After coating with a Mayer bar so that the coating amount after drying is 3 g / m ² , it is dried at 120 ° C. for 1 minute in a hot air dryer, and further between the resin layer and the aluminum vapor deposition layer. A paper laminate was obtained in the same manner as in Example 1 except that the resin layer of No. 2 was provided. Further, a paint for a sealant layer was applied onto the aluminum-deposited layer of the obtained paper laminate using Mayer bar (No. 16), and then dried in a hot air dryer at 120 ° C. for 1 minute to obtain a second. A paper laminate of Example 5 having the resin layer and the sealant layer of Example 5 was obtained.

[Comparative Example 1]
A paper laminate was obtained in the same manner as in Example 1 except that the vapor deposition layer was not provided.
Table 1 shows the evaluation results of the obtained paper laminate.

[Evaluation]
[Oxygen permeability]
Using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON), the oxygen permeability of the paper laminate can be measured under atmospheric pressure at a temperature of 23 ° C and a relative humidity of 50% (low humidity condition). It was measured. The lower the oxygen permeability value, the better the oxygen barrier property.
In addition, as an evaluation of processing resistance, oxygen permeability after bending was also measured. The folding method is as follows: the paper laminate is folded once and then opened (crease angle 180 °), then folded again along a line perpendicular to the folding line (crease angle 180 °), and then opened. The oxygen permeability was measured so that the intersection of the polygonal lines came to the center of the measuring section.

[Water vapor permeability]
In accordance with JIS Z0208 (cup method) B method (temperature 40 ° C ± 0.5 ° C, relative humidity 90% ± 2%), the resin layer of the paper laminate is arranged so that it is on the inside (low humidity side). The water vapor permeability was measured. The lower the value of water vapor permeability, the better the water vapor barrier property.
In addition, as an evaluation of processing resistance, the water vapor permeability after bending was also measured. The folding method is as follows: once the paper laminate is folded (fold angle 180 °), it is opened, then it is folded again along a line perpendicular to the folding line (fold angle 180 °), and then opened, and the folding line is in the center of the measuring section. The water vapor permeability was measured so that the intersection of the above was reached.

In the paper laminate of the example, both the oxygen permeability and the water vapor permeability are maintained at low values even after bending as compared with the comparative example, and even if the paper laminate is bent when used for a packaging bag or a packaging container, the value is maintained. It can be seen that a high barrier property can be maintained.

Claims (12)

A resin layer is provided on at least one surface of the paper substrate, and a vapor-deposited layer made of a metal or ceramic having a thickness of 1 to 1000 nm is provided on the resin layer. A paper laminate characterized by containing the above-mentioned plate-like inorganic compound. The paper laminate according to claim 1, wherein the paper substrate has a basis weight of 20 to 500 g / m ^2. The paper laminate according to claim 1 or 2, wherein the vapor-deposited layer is made of aluminum, silicon oxide, or aluminum oxide. The water-suspendable polymer in the resin layer is one or more selected from the group consisting of olefin / unsaturated carboxylic acid-based copolymers, styrene / butadiene-based copolymers, and styrene / acrylic-based copolymers. The paper laminate according to any one of claims 1 to 3. The paper laminate according to any one of claims 1 to 4, wherein the plate-like inorganic compound in the resin layer is at least one selected from the group consisting of synthetic mica, bentonite, and kaolin. The paper laminate according to any one of claims 1 to 5, wherein the resin layer contains 0.1% by mass or more and 70% by mass or less of a plate-like inorganic compound. The paper laminate according to any one of claims 1 to 6, wherein the resin layer contains a cationic resin. The paper laminate according to any one of claims 1 to 7, further comprising a sealant layer on the vapor-deposited layer. The paper laminate according to any one of claims 1 to 8, further comprising a second resin layer between the resin layer and the vapor-deposited layer. The paper laminate according to any one of claims 1 to 9, which is a material for packaging. A step of applying a resin layer paint to at least one surface of a paper base material and drying it to form a resin layer containing a water-suspendable polymer and a plate-like inorganic compound having an aspect ratio of 80 or more, and the resin layer. A method for manufacturing a paper laminate, which comprises a step of providing an aluminum vapor deposition layer on the paper laminate. The method for producing a paper laminate according to claim 11, further comprising a step of providing a second resin layer on the resin layer as a pre-process of a step of providing an aluminum vapor-deposited layer on the resin layer.