TW201941958A - Paper barrier material - Google Patents

Abstract

An object of the present invention is to provide a paper barrier material which has excellent water vapor barrier properties and which little environmental impact. A paper barrier material has at least a water vapor barrier coating layer on a paper substrate, wherein the water vapor barrier coating layer has at least a water vapor barrier resin A having a melting point of 110 DEG C or higher and a water vapor barrier resin B having a melting point less than 110 DEG C. The water vapor barrier resin A and the water vapor barrier resin B are preferably water-soluble or water-dispersible water-based resins.

Description

   Paper barrier material   

The present invention relates to a paper barrier material having excellent water vapor barrier properties.

In a wide range of fields such as packaging materials or containers for food, cosmetics, pesticides, pharmaceuticals, and miscellaneous goods, construction materials, and industrial materials, gas barrier properties and water vapor barrier properties are important properties that affect the preservation of the contents.

In the past, to provide gas barrier properties to paper packaging materials, the following methods have been mainly used: on a paper substrate (base paper), a metal foil made of metal such as aluminum, a metal vapor-deposited film, and polyvinyl alcohol , Ethylene-vinyl alcohol copolymer, polyvinyl chloride, polyacrylonitrile, and other resin films, or films made by coating these resins, or inorganic oxides such as vaporized silicon oxide or aluminum oxide The resulting ceramic vapor-deposited film or the like is used as a gas barrier layer, and is extruded or laminated on a paper substrate (original paper).

As for a paper packaging material having a gas barrier property other than the above, a paper gas barrier material having a gas barrier layer composed of a water-soluble polymer and an inorganic layered compound has been disclosed (Patent Document 1, Patent Document 1, 2) A paper gas barrier material (Patent Document 2) provided with a barrier layer made of a specific vinyl alcohol polymer on the coating layer.

In addition, a barrier material having a gas barrier property and a water vapor barrier property has been disclosed (Patent Document 3).

In addition, a resin composition has been disclosed that specifies the melting point of the resin contained in the gas barrier layer (Patent Document 4).

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent Laid-Open No. 2009-184138

[Patent Document 2] Japanese Patent Laid-Open No. 2003-094574

[Patent Document 3] Japanese Patent No. 5331265

[Patent Document 4] Japanese Patent Laid-Open No. 2000-001591

However, in the method of extruding and laminating the above-mentioned films or the like on a paper substrate (base paper), these films are not a sustainable raw material, and if incineration is performed, there will be problems of residue and carbon dioxide emission. If it is buried, it is a cause of marine waste because it is not biodegradable, and it has a problem of large environmental load.

Therefore, an object of the present invention is to provide a paper barrier material which has excellent water vapor barrier properties and has a small environmental load.

The present invention provides the following [1] to [10].

[1] A paper barrier material having at least a water vapor barrier coating layer on a paper substrate, wherein the water vapor barrier coating layer contains at least a water vapor barrier resin having a melting point of 110 ° C or higher A and water vapor barrier resin B with a melting point below 110 ° C.

[2] The paper barrier material according to [1], wherein the water vapor barrier resin A and the water vapor barrier resin B are water-soluble or water-dispersible water-based resins.

[3] The paper barrier material according to [2], wherein the water vapor barrier resin A is a water-soluble water-based resin, and the water vapor barrier resin B is a water-dispersible water-based resin.

[4] The paper barrier material according to any one of [1] to [3], further comprising a gas barrier coating layer on the aforementioned paper substrate.

[5] A paper barrier material, further comprising a protective layer on at least one side of the paper barrier material according to any one of [1] to [4].

[6] A packaging material using the paper barrier material according to any one of [1] to [5].

[7] A bag using the paper barrier material according to any one of [1] to [5].

[8] A tray using the paper barrier material according to any one of [1] to [5].

[9] A cup using the paper barrier material according to any one of [1] to [5].

[10] A liquid paper container using the paper barrier material according to any one of [1] to [5].

According to the present invention, a paper barrier material can be provided, which has excellent water vapor barrier properties. In addition, by making the water vapor barrier coating layer contain two or more resins having a specific melting point, the time for forming the resin film can be changed, and better water vapor barrier properties can be provided. Moreover, by providing a gas barrier coating layer on the paper substrate, a paper barrier material having excellent gas barrier properties and water vapor barrier properties can be provided.

In addition, since the main component is paper of a biomass material that is a sustainable raw material, from the viewpoint of carbon neutral, compared with a film derived from a fossil resource, it is possible to reduce the period from manufacture to disposal. Since the amount of carbon dioxide emitted up to this point is biodegradable, the possibility of causing environmental pollution even at the time of disposal is low, and the environmental load is small.

The present invention is a paper barrier material provided with at least a water vapor barrier coating layer on a paper substrate (hereinafter, sometimes referred to as "base paper"). The paper barrier material of the present invention may further be provided with a gas barrier coating layer on the paper substrate. In this case, the composition order of the layers is not particularly limited, but is preferably laminated in the order of a paper substrate, a water vapor barrier coating layer, and a gas barrier coating layer. These coating layers can be formed by applying and drying a coating liquid mainly using water as a medium using various coating apparatuses.

The reason why a paper barrier material having a water vapor barrier coating layer and a gas barrier coating layer in order to have both excellent water vapor barrier properties and gas barrier properties is presumed as follows.

As for the gas barrier resin used in the gas barrier coating layer, as exemplified below, it is generally a polymer such as a water-soluble polymer or a water-dispersible polymer. Gas barrier coatings and water vapor barrier coatings contain water-soluble polymers or high dispersibility due to moisture in the paper substrate or moisture in the air that penetrates through the paper substrate. Gas barrier coatings of polymers such as molecules are liable to deteriorate. On the other hand, if a water vapor barrier coating layer and a gas barrier coating layer containing a resin having good water resistance are sequentially provided on the paper substrate, the water vapor barrier coating layer can effectively suppress the paper base. The effect (deterioration) of moisture in the material on the gas barrier coating layer. Therefore, especially paper barrier materials having a water vapor barrier coating layer and a gas barrier coating layer in this order have good water vapor barrier properties and gas barrier properties.

(Paper substrate)

In the present invention, the paper substrate refers to a sheet mainly composed of pulp, and may contain fillers and various auxiliaries.

In terms of pulp, chemical pulp such as broadleaf bleached kraft pulp (LBKP), conifer bleached kraft pulp (NBKP), broadleaf unbleached kraft pulp (LUKP), conifer unbleached pulp (NUKP), sulfite pulp, and stone mill can be used Mechanical pulp such as pulp and thermomechanical pulp, wood fiber such as deinked pulp, waste paper pulp, non-wood fiber obtained from kenaf, bamboo, hemp, etc., polyester resin fiber such as polyethylene terephthalate, poly Polyolefin-based resin fibers such as acrylic and polyethylene, polyamide-based resin fibers such as nylon, and synthetic fibers such as halogen-containing resin fibers such as polyvinyl chloride can be appropriately blended and used.

As the filler, known fillers such as white carbon, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium oxide, zeolite, and synthetic resin fillers can be used. In addition, as needed, aluminum sulfate, various anionic or cationic or nonionic or amphoteric retention aids, water filtration enhancers, paper strength enhancers, internal auxiliaries for papermaking, and the like are used. Furthermore, if necessary, dyes, fluorescent whitening agents, pH adjusters, defoamers, pitch control agents, slime control agents, and the like may be added.

There is no particular limitation on the method for manufacturing (papermaking) the paper substrate. Known fourdrinier forming machines, ontop hybrid former machines, gap former machines, and Yangji paper machines ( Yankee machine) and the like to make paper substrates by acid paper making, neutral paper making, and alkaline paper making. In addition, the paper substrate may be a single layer, or may be composed of two or more layers.

The surface of the paper substrate may be treated with various chemical agents. Examples of the chemical agent used include, for example, oxidized starch, hydroxyethyl etherified starch, enzyme modified starch, polypropylene amidamine, polyvinyl alcohol, surface sizing agent, water resistance agent, water retention agent, and viscosity increasing agent. Agents, lubricants, etc. can be used alone or in combination of two or more.

Furthermore, these various chemical agents and pigments can be used in combination. As far as pigments are concerned, they can be used alone or in combination of two or more of the following: kaolin, clay, engineering kaolin, peeled clay, heavy calcium carbonate, light calcium carbonate, mica, talc, titanium dioxide, barium sulfate, calcium sulfate , Zinc oxide, silicic acid, silicate, colloidal silica, satin white, and other inorganic pigments; organic pigments such as compact, hollow, or core-shell.

The method of surface treatment of the paper substrate is not particularly limited, but a rod metering size press, a pool sizing press, a gate roll coater, a sprayer, Well-known coating apparatuses, such as a blade coater and a curtain coater.

Examples of the paper substrate obtained in this manner include high-quality paper, medium-quality paper, coated paper, single-sided glossy paper, kraft paper, single-sided glossy kraft paper, bleached kraft paper, glassine paper, cardboard, and white paper. Various known members such as boards and liners.

(Wet tensile strength)

Since the paper substrate of the present invention is coated with a coating liquid mainly using water as a medium, the strength of the paper substrate when wet with water is preferably more than a certain level. Therefore, the wet tensile strength in the papermaking direction (MD) is preferably 300 N / m or more.

(base weigh)

The paper substrate of the present invention can be set to an optimum basis weight according to the application, but is generally about 30 g / m ² to 600 g / m ² , and most of them are used from 30 g / m ² to 500 g / m ² .

(Barrier coating)

The paper barrier material of the present invention has a water vapor barrier coating layer on at least one side of a paper substrate. As described above, it is preferable to laminate the paper substrate, the water vapor barrier coating layer, and the gas barrier coating layer in this order.

(Water vapor barrier coating)

In the present invention, the water vapor barrier resin contained in the water vapor barrier coating layer may be used alone or in combination of two or more of the following: water-soluble or water-dispersible water vapor barrier properties Styrene / butadiene based, styrene / acrylic based, ethylene / vinyl acetate based, paraffin (WAX) based, polyester resin, butadiene / methyl methacrylate based, vinyl acetate / Various copolymers such as butyl acrylate, synthetic adhesives such as maleic anhydride copolymers, acrylic acid / methyl methacrylate copolymers, or these waxes (WAX) are prepared as adhesives. In the present invention, two or more kinds are preferably used in combination.

The water vapor barrier coating layer of the present invention contains at least a water vapor barrier resin A having a melting point of 110 ° C or higher and a water vapor barrier resin B having a melting point of less than 110 ° C.

Regarding a resin (a water-dispersible resin) such as an emulsion system in which particles are dispersed in water, the particles are formed into a film (film formation) as drying progresses. In general, the temperature band in which a water-dispersible resin is filmed is the melting point of the resin dispersed in water. On the other hand, as for the water-soluble resin, when the drying progresses, water belonging to the solvent evaporates, and the resin dissolved in the water is hardened to form a film (film formation). The temperature band at which the water-soluble resin hardens is dependent on the inherent melting point of the resin dissolved in water.

In the present invention, if it is a water-dispersible resin, it includes those in which the temperature band (melting point of the resin dispersed in water) where the film is formed is 110 ° C or higher and less than 110 ° C. If it is a water-soluble resin, it includes The temperature range (melting point of the resin dissolved in water) for curing is 110 ° C or higher and less than 110 ° C. It is estimated that if the melting point of each resin satisfies the above-mentioned range, since the melting point is a certain distance away from the vicinity of the boiling point of the water barrier, film formation will be performed sequentially from the low melting point, and a homogeneous resin film can be formed into a layer. , Excellent water vapor barrier properties.

In the present invention, if it is a combination of "water vapor barrier resin A having a melting point of 110 ° C or higher" and "water vapor barrier resin B having a melting point of less than 110 ° C", it may be a combination of water-soluble resins, Any one of a combination of water-dispersible resins and a combination of a water-soluble resin and a water-dispersible resin is preferable because the adhesion between the water vapor barrier coating layer and the paper substrate will be good, so water dispersion is preferred. Combination of water-soluble resin and water-soluble resin. Furthermore, it is more preferable that the water vapor barrier resin A having a melting point of 110 ° C or higher is a water-soluble resin, and the water vapor barrier resin B having a melting point of less than 110 ° C is a water-dispersible resin.

The melting point of the water vapor barrier resin can be measured by, for example, detecting the peak value of the endothermic reaction using a differential scanning thermal analyzer (DSC).

In addition, as long as it does not cause problems with water vapor barrier properties, the above water vapor barrier resins can be used in combination with: fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, ethylene copolymerized polyvinyl alcohol Polyvinyl alcohols such as casein, soy protein, synthetic proteins; starches such as oxidized starch, cationized starch, urea phosphate esterified starch, hydroxyethyl etherified starch; carboxymethyl cellulose, hydroxymethyl Cellulose derivatives such as cellulose and hydroxyethyl cellulose; water-soluble polymers such as polyvinylpyrrolidone and sodium alginate.

In the present invention, in the constitution having the water vapor barrier coating layer and the gas barrier coating layer, from the viewpoint of the adhesion between the water vapor barrier coating layer and the gas barrier coating layer, it is preferable that A pigment is contained in the water vapor barrier coating layer.

As far as pigments are concerned, they can be used alone or in combination of two or more of the following: kaolin, clay, engineering kaolin, exfoliated clay, mica, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate , Colloidal silica, satin white and other inorganic pigments, and compact, hollow, or core-shell type organic pigments.

Among these pigments, from the viewpoint of improving water vapor barrier properties and suppressing gas barrier coating penetration, flat inorganic pigments such as kaolin, talc, clay, and mica are more preferred, and more preferably Kaolin, mica. In addition, it is preferable to use 50% by volume average particle diameter (D50) (hereinafter, also referred to as "average particle diameter") of 5 μm or more and an aspect ratio of 10 or more when used alone or as a mixture of two or more kinds. The flat inorganic pigment is more preferably used by mixing two or more kinds. When the average particle diameter or aspect ratio of the inorganic pigment used is smaller than the above range, since the number of detours of the water vapor in the water vapor barrier coating layer is reduced and the moving distance is shortened, as a result, water will be caused. When the effect of improving the vapor barrier property becomes small.

In the present invention, when the pigment is contained in the water vapor barrier coating layer, it is preferably 30 parts by weight based on the dry weight, based on 100 parts by weight of the pigment, based on the total of the water vapor barrier resin and water-soluble polymer. It is contained in the range of more than 350 parts by weight. It is more preferably 50 parts by weight or more, and still more preferably 80 parts by weight or more. In addition, it is more preferably 250 parts by weight or less, and still more preferably 200 parts by weight or less.

In the present invention, a cross-linking agent represented by a polyvalent metal salt or the like may be added to the water vapor barrier coating layer. The crosslinking agent reacts with the water vapor barrier resin and water-soluble polymers contained in the water vapor barrier coating layer, so the number of bonds (crosslinking points) in the water vapor barrier coating layer. increase. That is, the water vapor barrier coating layer has a dense structure, and can exhibit good water vapor barrier properties.

In the present invention, the type of the cross-linking agent is not particularly limited, and the type of the water vapor barrier resin and the water-soluble polymer contained in the water vapor barrier coating layer can be combined, and a polyvalent metal salt (from Copper, zinc, silver, iron, potassium, sodium, zirconium, aluminum, calcium, barium, magnesium, titanium and other polyvalent metals and carbonate ions, sulfate ions, nitrate ions, phosphate ions, silicate ions, nitrogen oxides, boron oxidation Compounds such as ionic substances), amine compounds, amidine compounds, aldehyde compounds, hydroxy acids, and the like.

When a styrene-based water vapor barrier resin such as styrene / butadiene-based or styrene / acrylic acid-based resin exhibiting an excellent effect of water vapor barrier properties is used, it is preferable from the viewpoint of exhibiting a crosslinking effect. Polyvalent metal salts are used, and more preferably potassium alum is used.

Regarding the blending amount of the cross-linking agent, it can be blended without particular limitation as long as it is within the range of the concentration of paintable coating and the viscosity of the paint. It is more preferably 3 parts by weight or more and 5 parts by weight or less. When it is less than 1 part by weight, the effect of adding a crosslinking agent may not be sufficiently obtained. In addition, when the amount is more than 10 parts by weight, the viscosity of the coating material increases significantly, which may make coating difficult.

In the present invention, when a crosslinking agent is added to the coating material for a water vapor barrier coating layer, it is preferred that the crosslinking agent is dissolved in a polar solvent such as ammonia and added to the coating material. When the cross-linking agent is dissolved in a polar solvent, a bond is formed between the cross-linking agent and the polar solvent, so even if it is added to a coating, a cross-linking reaction with a water vapor barrier resin and a water-soluble polymer does not immediately occur. Therefore, thickening of the paint can be suppressed. In this case, it is estimated that after coating on a paper substrate, the polar solvent component is volatilized by drying, and a cross-linking reaction with a water vapor barrier resin and a water-soluble polymer occurs to form a dense water vapor barrier. Barrier coating.

In the present invention, in order to improve the water vapor barrier property, a water repellent agent may be contained in the water vapor barrier coating layer. Examples of the water-repellent agent include, for example, paraffin-based water-repellent agents mainly composed of alkane compounds, natural oils and oil-based water-repellent agents of source plants such as palm wax or lanolin, containing silicone or polysilicone. Polysiloxane-containing water repellent containing oxygen compounds, fluorine-containing water repellent containing fluorine compounds, and the like. Among these, it is preferable to use a paraffin-based water-repellent agent from the viewpoint of exhibiting water vapor barrier properties. These water-repellent agents can be used alone or in combination of two or more.

In the present invention, the blending amount of the water-repellent agent is not particularly limited, but the blending amount of the water-repellent agent is preferably based on dry weight with respect to 100 parts by weight of the total of the water vapor barrier resin and the water-soluble polymer. In other words, the water-repellent agent is from 1 part by weight to 100 parts by weight. When the amount of the water-repellent agent is less than 1 part by weight, there is a possibility that the effect of improving water vapor barrier properties may not be sufficiently obtained. On the other hand, when it exceeds 100 parts by weight, when a gas barrier coating layer is provided on the water vapor barrier coating layer, it becomes difficult to uniformly form the gas barrier coating layer, so that the gas barrier property is reduced. possibility.

In addition, in the present invention, from the viewpoint of the improvement of water vapor barrier properties and the adhesion with the gas barrier coating layer, the wetting tension on the surface of the water vapor barrier coating layer can be set to 10 mN / m or more and 60 mN / m. Below, if it is 15 mN / m or more and 50 mN / m or less, the effect will be more exhibited.

In the present invention, in addition to the above-mentioned water vapor barrier resin, water-soluble polymer, pigment, cross-linking agent, and water-repellent agent, in the water vapor barrier coating layer, a dispersant, a tackifier, and a water retention agent may be used Additives, defoamers, water-resistant agents, dyes, fluorescent dyes and other commonly used additives.

(Gas barrier coating)

In the present invention, the gas barrier coating layer may contain polymers such as water-soluble polymers and water-dispersible polymers having gas barrier properties.

In the present invention, the water-soluble polymer used in the gas barrier coating layer may be exemplified by polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and ethylene copolymerized polyvinyl alcohol; Proteins such as protein, soybean protein, synthetic protein; starches such as oxidized starch, cationized starch, urea phosphate esterified starch, hydroxyethyl etherified starch; carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl fiber Cellulose derivatives, such as cellulose; polyvinylpyrrolidone, sodium alginate, etc.

Among these, from the viewpoint of gas barrier properties, polyvinyl alcohols and cellulose derivatives are preferred, and polyvinyl alcohols are more preferred.

Examples of the water-dispersible polymer used in the gas barrier coating layer include polyvinyl chloride, ethylene vinyl acetate-based resin, and modified polyolefin-based resin.

In the present invention, from the viewpoint of improving the gas barrier property, it is preferable that the gas barrier coating layer contains a pigment. As for the pigments used in the gas barrier coating layer, they can be used alone or in combination of two or more of the following: kaolin, clay, engineering kaolin, exfoliated clay, heavy calcium carbonate, light calcium carbonate, mica, Inorganic pigments such as talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, satin white, and organic pigments such as compact, hollow, or core-shell.

Among these, from the viewpoint of gas barrier properties, it is preferable to use flat inorganic pigments such as kaolin, talc, clay, mica, and the like, and more preferably to use an average particle diameter of 3 μm or more and an aspect ratio of 10. The above flat inorganic pigment is more preferably a flat inorganic pigment having an average particle diameter of 5 μm or more and an aspect ratio of 30 or more.

When a pigment is contained in the gas barrier coating layer, gas such as oxygen will bypass the pigment. Therefore, compared with a gas barrier coating layer composed of a polymer such as a water-soluble polymer or a water-dispersible polymer that does not contain a pigment, it has more excellent gas barrier properties in a high humidity environment.

In the present invention, the gas barrier coating layer containing a flat inorganic pigment having an average particle diameter of 5 μm or more and an aspect ratio of 10 or more may further contain a pigment having an average particle diameter of 5 μm or less. By using a pigment having an average particle diameter of 5 μm or less in combination, it is possible to reduce voids in a gas barrier coating layer formed by a flat inorganic pigment having an average particle diameter of 5 μm or more and an aspect ratio of 10 or more. Gas barrier properties. That is, when the gas barrier coating layer contains pigments having different average particle diameters, it is estimated that in the gas barrier coating layer, a "pigment with a small average particle diameter" will be filled with "an inorganic with a large average particle diameter" In the state of "voids formed by pigments", oxygen and other gases will bypass the pigments, so they are higher in gas barrier properties than gas barrier coatings that do not contain pigments with different average particle diameters.

In the present invention, when a flat inorganic pigment having an average particle diameter of 5 μm or more and an aspect ratio of 10 or more is used in combination with a pigment having an average particle diameter of 5 μm or less, the flat inorganic pigment having an average particle diameter of 5 μm or more and an aspect ratio of 10 or more The blending ratio of the pigment to the pigment having an average particle diameter of 5 μm or less can be set to 50/50 to 99/1 on a dry weight basis. When the blending ratio of the flat inorganic pigment having an average particle diameter of 5 μm or more and an aspect ratio of 10 or more is less than the above range, the number of detours of the gas such as oxygen in the gas barrier coating layer is reduced, and the moving distance is shortened, so that In cases where the gas barrier improvement effect becomes small. On the other hand, if it is more than the above range, the void formed by the inorganic pigment having a large average particle diameter in the gas barrier coating layer cannot be sufficiently buried with a pigment having an average particle diameter of 5 μm or less, so the gas barrier cannot be seen. Further improvement of obstacles.

In the present invention, a pigment having an average particle diameter of 5 μm or less in combination with a flat inorganic pigment having an average particle diameter of 5 μm or more and an aspect ratio of 10 or more may be used alone or as a mixture of two or more of the following: kaolin , Clay, engineering kaolin, peeled clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, satin white and other inorganic pigments And compact, hollow, or core-shell type organic pigments. Among these pigments, heavy calcium carbonate is preferably used.

In the present invention, when a pigment is contained in the gas barrier coating layer, the mixing ratio of the pigment to the water-soluble polymer and the water-dispersible polymer is preferably pigment / (water-soluble polymer and water-dispersible polymer) on a dry weight basis. Total) = 1/100 to 1000/100. When the ratio of the pigment exceeds the above range, the effect of improving the gas barrier property may be reduced.

In addition, in the present invention, when the pigment is formulated in a water-soluble polymer or a water-dispersible polymer, it is preferable to add and mix the pigment by slurrying it.

In the present invention, a cross-linking agent typified by a polyvalent metal salt or the like may be added to the gas barrier coating layer. The crosslinker reacts with polymers such as water-soluble polymers and water-dispersible polymers contained in the gas barrier coating layer, so the number of bonds (crosslinking points) in the gas barrier coating layer. Will increase. That is, the gas barrier coating layer has a dense structure, and can exhibit good gas barrier properties.

In the present invention, the type of the cross-linking agent is not particularly limited, and the types of polymers such as water-soluble polymers and water-dispersible polymers contained in the gas barrier coating layer can be appropriately selected and used. By copper, zinc, silver, iron, potassium, sodium, zirconium, aluminum, calcium, barium, magnesium, titanium and other polyvalent metals and carbonate ions, sulfate ions, nitrate ions, phosphate ions, silicate ions, nitrogen oxides, boron Ionic compounds such as oxides), amine compounds, amidine compounds, aldehyde compounds, hydroxy acids, and the like. From the viewpoint of exhibiting a crosslinking effect, it is preferred to use a polyvalent metal salt, and more preferred to use potassium alum.

Regarding the blending amount of the cross-linking agent, it can be blended without particular limitation as long as it is within the range of the concentration of paintable coating and the viscosity of the paint. It is more preferably 3 parts by weight or more and 5 parts by weight or less. When it is less than 1 part by weight, the effect of adding a crosslinking agent may not be sufficiently obtained. In addition, when the amount is more than 10 parts by weight, the viscosity of the coating material increases significantly, which may make coating difficult.

In the present invention, in order to improve the adhesion with the water vapor barrier coating layer, a surfactant may be contained in the gas barrier coating layer. The ionicity of the surfactant is not limited. No matter it is an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a nonionic surfactant, it can be used alone or in combination of two or more. While using. Specific examples include polysiloxane surfactants, fluorine surfactants, alcohol surfactants, acetylene surfactants having an acetylene group, and acetylene glycols having an acetylene group and two hydroxyl groups. Surfactant, alkylsulfonic acid surfactant with alkyl and sulfonic acid, ester surfactant, ammonium surfactant, amine surfactant, alkyl ether surfactant, phenyl Ether-based surfactants, sulfate-based surfactants, phenol-based surfactants, and the like. Among these, it is preferable to use an acetylene glycol-based surfactant having a large effect of improving the leveling property of the coating. In addition, when the leveling of the coating is improved, the uniformity of the gas barrier coating layer will be improved, so the gas barrier property will be improved.

In the present invention, the surface tension of the coating material for the gas barrier coating layer can be adjusted from 10 mN / m to 60 mN / m from the viewpoint of the adhesion with the water vapor barrier coating layer. It is preferably adjusted to be 15 mN / m or more and 50 mN / m or less.

In addition, from the viewpoint of the adhesion between the water vapor barrier coating layer and the gas barrier coating layer, it is preferable to use the gas barrier coating layer with respect to the wet tension of the surface of the water vapor barrier coating layer. The surface tension of the paint was set to ± 20 mN / m.

In the present invention, in addition to the above water-soluble polymer, water-dispersible polymer, pigment, cross-linking agent, and surfactant, in the gas barrier coating layer, dispersant, tackifier, water-retaining agent, Various additives commonly used such as defoamers, water-resistant agents, dyes, and fluorescent dyes.

(Coating of water vapor barrier coating layer and gas barrier coating layer)

In the present invention, the coating method of the water vapor barrier coating layer and the gas barrier coating layer is not particularly limited, and can be applied by a known coating device and coating system. Examples of the coating device include a blade coater, a bar coater, a roll coater, an air knife coater, a reverse roll coater, a curtain coater, a sprayer, and a size press Device, gate roller applicator, etc. In addition, the coating system is preferably an aqueous coating system mainly using water as a medium.

As a method for drying the water vapor barrier coating layer and the gas barrier coating layer, for example, a steam heater, a gas heater, an infrared heater, an electric heater, a hot air heater, a microwave, and a drum dryer can be used. And so on.

In the present invention, the coating amount of the water vapor barrier coating layer is preferably 3 g / m ² or more and 50 g / m ² or less on a dry weight basis, and more preferably 5 g / m ² or more and 40 g / m ² or less. Still more preferably, it is 7 g / m ² or more and 20 g / m ² or less. When the coating amount of the water vapor barrier coating layer is less than 3 g / m ² , the coating liquid may become difficult to completely cover the paper substrate, and sufficient water vapor barrier properties may not be obtained, or the gas barrier coating may be applied. In cases where the coating penetrates into the paper substrate and sufficient gas barrier properties cannot be obtained. On the other hand, if it is more than 50 g / m ² , the drying load during coating becomes large.

In addition, in the present invention, the water vapor barrier coating layer may be one layer, or may be composed of two or more layers. When the water vapor barrier coating layer is composed of two or more layers, the total coating amount of the entire water vapor barrier coating layer is preferably set to the above range.

In the present invention, the coating amount of the gas barrier coating layer is preferably 0.2 g / m ² or more and 20 g / m ² or less on a dry weight basis. When the coating amount of the gas barrier coating layer is less than 0.2 g / m ² , it is difficult to form a uniform gas barrier coating layer, and therefore, sufficient gas barrier properties may not be obtained. On the other hand, when it is more than 20 g / m ² , the drying load during coating becomes large.

In addition, in the present invention, the gas barrier coating layer may be one layer, or may be composed of two or more layers. When the gas barrier coating layer is composed of two or more layers, the total coating amount of the entire gas barrier coating layer is preferably set to the above range.

(The protective layer)

The paper barrier material of the present invention may further have a protective layer on at least one side. The protective layer can prevent the influence (deterioration) on the water vapor barrier coating layer and the gas barrier coating layer of the paper barrier material caused by the moisture in the air or the friction and cracking of the barrier coating layer, and Paper barrier materials can be further provided with water vapor barrier properties, gas barrier properties, or oil resistance, solvent resistance, heat resistance, abrasion resistance, impact resistance, light resistance, water resistance, and the like. In addition, when the protective layer is a resin layer, heat sealability can be imparted.

It is also possible to provide protective layers on both sides of the paper barrier material, but it is preferable to have a protective layer on at least the side having the water vapor barrier coating layer. Furthermore, as for a paper barrier material having a water vapor barrier coating layer and a gas barrier coating layer in order on a paper substrate, if a protective layer is provided on the gas barrier coating layer, It is preferable to prevent the influence (deterioration) on the water vapor barrier coating layer and the gas barrier coating layer due to moisture in the air and the like.

Examples of the protective layer include a resin layer, a paper layer, and a metal foil. Among these, a resin layer is preferred. However, in the case of applications requiring biodegradability, those used for the protective layer are preferably those having biodegradability such as biodegradable resin.

(Resin layer)

The resin of the resin layer may contain: polyester, polyvinyl alcohol, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, polymethylpentyl Ene, polyvinyl chloride, acrylonitrile / butadiene / styrene, acrylonitrile / styrene, polymethyl methacrylate, polyvinyl chloride, polyamide (nylon), polyacetal, polycarbonate, etc. Fossil-derived resins, polylactic acid (PLA), esterified starch, cellulose acetate, polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), bio-polyethylene, raw materials Bio-derived resins such as high-quality polyethylene terephthalate and bio-based polyurethane.

In addition, a bio-derived resin refers to a polymer material containing a substance derived from a renewable organic resource as a raw material and having a number average molecular weight (Mn) of 1,000 or more that can be synthesized chemically or biologically.

In addition, for resins derived from fossil resources and resins derived from living things, polylactic acid (PLA), esterified starch, cellulose acetate, polybutylene succinate (PBS), and adipic acid polysuccinate can be used. Biodegradable resins such as butyl butyrate (PBSA), polyethylene, polypropylene, polyester, polyethylene terephthalate, polyamide (nylon), and biopolyethylene are not biodegradable Any of the resins.

In addition, the biodegradable resin refers to a resin that is decomposed into sub-layers by the action of microorganisms, and eventually turns into carbon dioxide and water and circulates in nature.

In the present invention, the resin layer is preferably a resin laminate layer. Examples of the resin laminate layer include a film laminate layer such as an extrusion laminate layer, a barrier film, and a vapor-deposited film.

When the resin laminated layer is an extruded laminated layer, it is attached to at least one side of a paper barrier material, and the above-mentioned various resins are laminated by the extrusion lamination method as a resin laminated layer. In addition, when the resin laminated layer is a film bonding layer, it is attached to at least one side of the paper barrier material, and the above-mentioned various resin films are bonded to the resin laminate by a dry layer method, a sandwich type method, and the like. Floor.

In this invention, the film used for the film bonding layer includes the above-mentioned various resin films. Among these films, it is preferable to use a film mainly composed of a resin such as polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, polyvinylidene chloride, and polyacrylonitrile, and apply the polymer to a film made of the above-mentioned various resins. A film made of a resin such as vinyl alcohol, a film made by bonding a metal foil containing various metals such as aluminum to the above-mentioned various resin films, and a variety of metals such as aluminum, silicon oxide, and alumina deposited on the above-mentioned various resin films Barrier films such as vapor-deposited films made of inorganic oxides are more preferably vapor-deposited films. Depending on the purpose, one or more of these films can be laminated and used.

(Barrier)

The paper barrier material of the present invention preferably has the following barrier properties. In addition, the following barrier value is a value measured in the state in which the said protective layer was not formed. The paper barrier material of the present invention has excellent barrier properties even when various films and metal foils are not used.

(1) Water vapor penetration at a temperature of 40 ± 0.5 ℃ and a relative humidity difference of 90 ± 2% is less than 200g / m ² ˙day; (2) Oxygen penetration at a temperature of 23 ℃ and a relative humidity of 0% The degree is 5ml / m ² ˙day˙atm or less; more preferably, it has the following barrier properties: (3) The water vapor permeability is 50g / at a temperature of 40 ± 0.5 ℃ and a relative humidity difference of 90 ± 2%. m ² ˙day or less; (4) The oxygen permeability at a temperature of 23 ° C. and a relative humidity of 0% is 3 ml / m ² ˙day˙atm or less.

Regarding the paper barrier material of the present invention, the paper barrier material can be maintained as it is, or it can be laminated with various universal films, barrier films, aluminum foils, etc. that can be laminated with various resins, etc. to make food, etc. Packaging materials, bags, paper containers, corrugated boxes, trays, cups, liquid paper containers, and other packaging materials used for packaging purposes, or can be used as industrial materials and construction materials and other laminated bodies. Among these, it can be suitably used as a packaging material for packaging materials such as food, bags, paper, corrugated boxes, trays, cups, liquid paper containers, and the like, and particularly suitable as a flexible packaging material for food. . In addition, a flexible packaging material refers to a packaging material whose composition is made of a material rich in flexibility. Generally speaking, it refers to a single or laminated thin, flexible material such as paper, film, and aluminum foil. Packaging materials. In addition, in terms of shape, it refers to a packaging material such as a bag that maintains a three-dimensional shape by putting contents therein.

When the paper barrier material of the present invention is used to make a packaging material for foods (especially a flexible packaging material), it can be laminated with a heat-sealing resin to improve the sealability of the packaging material and protect it. The contents are protected from oxidation due to oxygen and deterioration due to moisture, etc., and the storage period can be extended.

In addition, when used as a laminate for industrial materials, construction materials, etc., it can prevent corruption and deterioration by inhibiting the intrusion of oxygen or moisture, and it can also be expected to prevent the odor barrier of solvent leakage. And other effects.

    [Example]    

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited to these examples. In addition, unless otherwise specified, "part" and "%" in the examples represent parts by weight and% by weight, respectively. The obtained paper barrier material was tested in accordance with the evaluation method shown below.

(assessment method)

(1) Water vapor transmission rate: Under the conditions of a temperature of 40 ± 0.5 ° C and a relative humidity difference of 90 ± 2%, measurement was performed using a moisture permeability measuring device (L80-4000, manufactured by Dr. Lyssy). The measurement was performed using a paper barrier material before the protective layer was provided.

(2) Oxygen transmission rate: An oxygen transmission rate measuring device (OX-TRAN2 / 21, manufactured by MOCON, Inc.) was used to measure under conditions of 23 ° C and 0% RH and conditions of 23 ° C and 85% RH. The measurement was performed using a paper barrier material before the protective layer was provided.

(3) Melting point: Measured by detecting a peak value of an endothermic reaction using a differential scanning thermal analyzer (manufactured by Shimadzu Corporation, DSC-60Plus).

[Example 1]

    (Manufacture of paper substrate)    

100 parts by weight of broadleaf kraft pulp (LBKP) of 320 ml of Canadian Standard Freeness (CSF; Canadian Standard Freeness) was used as the raw material pulp. The raw material pulp was paper-made with a Fourdrinier paper machine to obtain a paper having a basis weight of 63.0 g / m ² . Next, the obtained paper was coated and dried with starch (Rocorns (manufactured by Sunus Co., Ltd.) having a solid content concentration of 3% so that both sides were 1.0 g / m ^{2 in} total, and dried using a chilled calender. ) Smoothing was performed at a speed of 300 min / m and a linear pressure of 50 kgf / cm one pass to obtain a paper substrate having a basis weight of 64.0 g / m ² .

    (Preparation of coating liquid A1 for water vapor barrier coating layer)    

In engineering kaolin (BARRISURF HX, manufactured by IMERYS Corporation, particle diameter 9.0 μm, aspect ratio 80 to 100), sodium polyacrylate (0.2 parts with respect to pigment) is added as a dispersant, and dispersed in a Cellier mixer to prepare a solid form. 60% kaolin clay slurry. In the obtained kaolin slurry, water vapor barrier resin A (polyethylene resin, manufactured by Mitsui Chemicals, CHEMIPEARL W400, melting point) was used as a water vapor barrier resin with respect to 100 parts (solid content) of the pigment. 110 ° C) becomes 50 parts (solid content), water vapor barrier resin B (acrylic resin, manufactured by Sumitomo Chemical Co., Ltd., ZAIKTHENE N, melting point 90 ° C) becomes 50 parts (solid content), and the paraffin-based water repellent agent (MYE-35G, a polyethylene emulsion containing wax, manufactured by Marubeni Chemical Co., Ltd.) was formulated so as to be 100 parts (solid content) to obtain a coating liquid A1 for a water vapor barrier coating layer having a solid content concentration of 45%.

    (Preparation of coating liquid B1 for gas barrier coating layer)    

An aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA117) was prepared so that the solid content concentration was 10%. In the obtained aqueous solution of polyvinyl alcohol, 100 parts (solid content) of polyvinyl alcohol was prepared so that a polysiloxane surfactant (SN WET 125, manufactured by SAN NOPCO, Inc.) became 1 part (solid content). Thus, a coating liquid B1 for a gas barrier coating layer was obtained.

    (Manufacture of paper barrier materials)    

On the obtained paper substrate, a coating liquid A1 for a water vapor barrier coating layer was applied so that the coating amount became 15 g / m ² on a dry weight basis using a doctor blade coater at a coating speed of 300 m / min. After one-side coating and drying, a coating liquid B1 for a gas barrier coating layer was applied thereon so that the coating amount became 5.0 g / m ² in terms of dry weight using a roll coater at a coating speed of 300 m One-sided coating was performed per minute to obtain a paper barrier material.

[Example 2]

    (Preparation of coating liquid A2 for water vapor barrier coating layer)    

In addition to changing the water vapor barrier resin A (polyethylene resin, manufactured by Mitsui Chemicals, CHEMIPEARL W400, melting point 110 ° C) to 60 parts (solid content), the water vapor barrier resin B (acrylic resin, A coating liquid A2 for a water vapor barrier coating layer was obtained in the same manner as in Example 1 except that ZAIKTHENE N (melting point: 90 ° C.) manufactured by Sumitomo Chemical Co., Ltd. was changed to 40 parts (solid content).

    (Manufacture of paper barrier materials)    

A paper barrier material was obtained in the same manner as in Example 1 except that the coating liquid A2 for a water vapor barrier coating layer was used instead of the coating liquid A1 for a water vapor barrier coating layer.

[Example 3]

    (Preparation of coating liquid A3 for water vapor barrier coating layer)    

In addition to changing the water vapor barrier resin A (polyethylene resin, manufactured by Mitsui Chemicals, CHEMIPEARL W400, melting point 110 ° C) to 40 parts (solid content), the water vapor barrier resin B (acrylic resin, A coating liquid A3 for a water vapor barrier coating layer was obtained in the same manner as in Example 1 except that ZAIKTHENE N (melting point: 90 ° C.) manufactured by Sumitomo Chemical Co., Ltd. was changed to 60 parts (solid content).

    (Manufacture of paper barrier materials)    

A paper barrier material was obtained in the same manner as in Example 1 except that the coating liquid A3 for a water vapor barrier coating layer was used instead of the coating liquid A1 for a water vapor barrier coating layer.

[Comparative Example 1]

    (Preparation of coating liquid A4 for water vapor barrier coating layer)    

In addition to changing the water vapor barrier resin A (polyethylene resin, manufactured by Mitsui Chemicals, CHEMIPEARL W400, melting point 110 ° C) to 100 parts (solid content), the water vapor barrier resin B (acrylic resin, A coating liquid A4 for a water vapor barrier coating layer was obtained in the same manner as in Example 1 except that ZAIKTHENE N (melting point: 90 ° C.) manufactured by Sumitomo Chemical Co., Ltd. was changed to 0 parts (solid content).

    (Manufacture of paper barrier materials)    

A paper barrier material was obtained in the same manner as in Example 1 except that the coating liquid A4 for a water vapor barrier coating layer was used instead of the coating liquid A1 for a water vapor barrier coating layer.

As shown in Table 1, when the water vapor barrier coating layer contains at least a water vapor barrier resin A having a melting point of 110 ° C or higher and a water vapor barrier resin B having a melting point of less than 110 ° C, the water vapor barrier property And gas barrier properties are excellent.

Claims (10)

    A paper barrier material has at least a water vapor barrier coating layer on a paper substrate, wherein the water vapor barrier coating layer contains at least a water vapor barrier resin A having a melting point of 110 ° C. and a melting point. Water vapor barrier resin B below 110 ° C.         The paper barrier material according to item 1 of the patent application scope, wherein the water vapor barrier resin A and the water vapor barrier resin B are water-soluble or water-dispersible water-based resins.         The paper barrier material according to item 2 of the scope of the patent application, wherein the water vapor barrier resin A is a water-soluble water-based resin, and the water vapor barrier resin B is a water-dispersible water-based resin.         The paper barrier material according to any one of claims 1 to 3 of the scope of application for a patent, has a gas barrier coating layer on the aforementioned paper substrate.         A paper barrier material is provided with a protective layer on at least one side of the paper barrier material described in any one of claims 1 to 4 of the scope of patent application.         A packaging material is a paper barrier material described in any one of claims 1 to 5 of the scope of patent application.         A bag is made of a paper barrier material as described in any one of claims 1 to 5.         A tray uses a paper barrier material as described in any one of claims 1 to 5 of the scope of patent application.         A cup is a paper barrier material described in any one of the first to fifth scope of the patent application.         A liquid paper container using the paper barrier material described in any one of claims 1 to 5 of the scope of patent application.