TW201945198A - Paper barrier material - Google Patents

Abstract

An objective of the present invention is to provide a paper barrier material which has excellent barrier properties and a low environmental load. The paper barrier material of the present invention has a barrier coating layer comprising at least one layer of pigment on a paper substrate, wherein the barrier coating layer contains 50 mass% or more of at least two kinds of flat inorganic pigment A and flat inorganic pigment B with respect to the total pigment of the barrier coating layer. The flat inorganic pigment A is preferably mica, and the flat inorganic pigment B preferably has an aspect ratio of 10 or more.

Description

   Paper barrier material   

The present invention relates to a paper barrier material having excellent 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, various barrier properties (especially gas barrier properties and water vapor barrier properties) are in control. Important properties of content preservation.

In the past, to provide gas barrier properties to paper packaging materials, the following methods have been mainly used: on a paper substrate (raw paper), a metal foil made of metal such as aluminum, a metal vapor-deposited film, and polyethylene Alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyacrylonitrile and other resin film, or a film made by coating these resins, or vapor-deposited silica or alumina, etc. A ceramic vapor-deposited film made of an inorganic oxide 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) Materials such as a paper gas barrier material (Patent Document 2) in which a barrier layer composed of a specific vinyl alcohol polymer is provided on the coating layer.

In addition, a resin composition and application that specify the compounding ratio of the inorganic layered compound of the gas barrier layer and the like are also disclosed (Patent Document 3), but there is no description about water vapor barrier properties.

In addition, a barrier material having additional gas barrier properties and water vapor barrier properties is also disclosed (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. 3898536

[Patent Document 4] Japanese Patent No. 5331265

However, in the method of extruding and laminating the above-mentioned film 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. Landfill disposal is a cause of marine debris due to non-biodegradability, and has a large environmental load.

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

The present invention provides a paper barrier material having the following features [1] to [12].

[1] A paper barrier material having at least one pigment-containing barrier coating layer on a paper substrate, wherein in the barrier coating layer, relative to the entirety of the barrier coating layer The pigment contains at least two kinds of the flat inorganic pigment A and the flat inorganic pigment B in an amount of 50% by weight or more.

[2] The paper barrier material according to [1], wherein the flat inorganic pigment A is mica, and the aspect ratio of the flat inorganic pigment B is 10 or more.

[3] The paper barrier material according to [1] or [2], wherein the flat inorganic pigment B is kaolin.

[4] The paper barrier material according to any one of [1] to [3], wherein an aspect ratio of the flat inorganic pigment B is 30 or more.

[5] The paper barrier material according to any one of [1] to [4], wherein the barrier coating layer has water vapor barrier property and / or gas barrier property.

[6] The paper barrier material according to [5], wherein the barrier coating layer has at least water vapor barrier property.

[7] 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 [6].

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

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

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

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

[12] A liquid paper container using the paper barrier material according to any one of [1] to [7].

According to the present invention, a paper barrier material can be provided, which has excellent barrier properties. Furthermore, by providing at least one barrier coating layer with a specific amount of at least two kinds of flat inorganic pigments, it is possible to impart more excellent barrier properties. Furthermore, the barrier coating layer has both water vapor barrier properties and gas barrier properties, or the barrier coating layer is made of a water vapor barrier coating layer having water vapor barrier properties and The combination of gas barrier coating and gas barrier coating can provide paper barrier materials with excellent gas barrier and water vapor barrier properties.

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, which is provided with at least one pigment-containing barrier coating layer on a paper substrate (hereinafter, sometimes referred to as "base paper"), wherein the barrier coating layer is The flat inorganic pigment A and the flat inorganic pigment B are contained in 50% by weight or more of all the pigments in the barrier coating layer.

The barrier coating layer of the present invention preferably has water vapor barrier properties and / or gas barrier properties, and more preferably has at least water vapor barrier properties. In addition, the barrier coating layer can have both water vapor barrier properties and gas barrier properties, or the barrier coating layer can be a water vapor barrier coating layer having water vapor barrier properties and a gas barrier layer. The combination of the barrier gas barrier coating layer can obtain a paper barrier material having excellent gas barrier properties and water vapor barrier properties, so it is preferable. When the barrier coating layer is a combination of a water vapor barrier coating layer having water vapor barrier properties and a gas barrier coating layer having gas barrier properties, the composition order of each layer is not particularly limited, but Preferably, the paper substrate, the water vapor barrier coating layer, and the gas barrier coating layer are laminated in this order.

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 will be described later, it is generally a polymer such as a water-soluble polymer or a water-dispersible polymer. When a gas barrier is sequentially provided on a paper substrate, When the barrier coating layer or the water vapor barrier coating layer contains water-soluble polymers or water-dispersible polymers due to the moisture in the paper substrate or the moisture in the air penetrated through the paper substrate, etc. The polymer gas barrier coating layer is 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.

    (Barrier coating)    

The paper barrier material of the present invention has at least one pigment-containing barrier coating layer on at least one side of a paper substrate, wherein the barrier coating layer is opposite to the barrier coating layer. All pigments contain at least two types of flat inorganic pigment A and flat inorganic pigment B in an amount of 50% by weight or more. As mentioned above, the barrier coating layer preferably has water vapor barrier properties and / or gas barrier properties, and more preferably has at least water vapor barrier properties. In addition, it is preferable that the barrier coating layer has both water vapor barrier properties and gas barrier properties, or the barrier coating layer is a water vapor barrier coating layer having water vapor barrier properties and The combination of gas-barrier gas barrier coatings is more preferably laminated in the order of a paper substrate, a water vapor barrier coating, and a gas barrier coating.

    (Water vapor barrier resin)    

In the present invention, the water vapor barrier resin contained in the barrier coating layer may be used alone or as a mixture of two or more of the following: benzene which is a water-soluble or water-dispersible water-based resin having water vapor barrier properties Ethylene / butadiene, styrene / acrylic, ethylene / vinyl acetate, wax (WAX), polyester resin, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, etc. Synthetic adhesives such as various copolymers, maleic anhydride copolymers, acrylic acid / methyl methacrylate copolymers, or these waxes (WAX) are blended to form adhesives. In the present invention, two or more kinds are preferably used in combination. From the viewpoint of water vapor barrier properties and adhesion to a paper substrate, a combination of a water-dispersible resin and a water-soluble resin is preferable.

    (Gas barrier resin)    

In the present invention, the gas barrier resin contained in the barrier coating layer is a polymer such as a water-soluble polymer and a water-dispersible polymer having gas barrier properties. Examples of water-soluble polymers include polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and ethylene copolymerized polyvinyl alcohol; proteins such as casein, soybean protein, and synthetic protein; oxidized starch , Cationized starch, urea phosphated starch, hydroxyethyl etherified starch and other starches; cellulose derivatives such as carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl 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 include polyvinyl chloride, ethylene vinyl acetate-based resin, and modified polyolefin-based resin.

    (Other resins)    

In the present invention, various known resins other than the water vapor barrier resin and the gas barrier resin may be used in combination as long as they do not cause problems with water vapor barrier properties and gas barrier properties.

    (Pigment)    

In the present invention, at least two types of flat inorganic pigment A and flat inorganic pigment B are contained in at least one barrier coating layer. As the flat inorganic pigment A and the flat inorganic pigment B, various known flat inorganic materials such as kaolin, talc, clay, bentonite, saponite, stibnite, montmorillonite, and mica can be used. In the present invention, the total amount of the flat inorganic pigment A and the flat inorganic pigment B is 50% by weight or more based on the total pigment of the barrier coating layer in the present invention.

It is preferably 60% by weight or more, and more preferably 70% by weight or more, with respect to all pigments.

When the total amount of the flat inorganic pigment A and the flat inorganic pigment B is less than 50% by weight with respect to all the pigments of the barrier coating layer, the water vapor and gas etc. are detoured in the barrier coating layer and the moving distance is small. Short, various barrier properties (especially water vapor barrier properties and gas barrier properties) become insufficient.

In the present invention, the flat inorganic pigment A is preferably mica.

Mica refers to one of the minerals with silicon as the main component. In the crystal, the four-sided system composed of silicon and oxygen is continuously extended into a thin sheet. This continuous structure will form a high flat shape. In particular, the swelling mica is preferable because it absorbs water molecules between the flaky structures and swells it, and cleavages it finely. Therefore, it is more likely to exhibit higher barrier properties than non-swelling mica.

In the present invention, when the barrier coating layer is a combination of a water vapor barrier coating layer containing a pigment and a gas barrier coating layer, mica in the water vapor barrier coating layer and a flat inorganic pigment other than mica If the content ratio of is flat inorganic pigments other than mica / mica = 60/40 to 5/95 (solid content ratio), the adhesion between the water vapor barrier coating layer and the gas barrier coating layer becomes good, and It is preferable to obtain high water vapor barrier properties and gas barrier properties. More preferred is 55/45 to 10/90, and more preferred is 50/50 to 15/85.

In the present invention, the flat inorganic pigment B preferably has an aspect ratio of 10 or more. Examples of the flat inorganic pigment B having an aspect ratio of 10 or more include, for example, kaolin, talc, clay, bentonite, saponite, antimony ore, and montmorillonite. Among these, from the viewpoints of both improving water vapor barrier properties and inhibiting gas barrier layer penetration, kaolin, bentonite, and montmorillonite are more preferable, and kaolin and bentonite are more preferable.

When the flat inorganic pigment A is mica and the flat inorganic pigment B has an aspect ratio of 10 or more, the number of detours of water vapor and gas in the barrier coating layer increases and the moving distance becomes longer, so the water vapor barrier property and gas The improvement effect of barrier properties becomes large. In particular, the improvement effect of the gas barrier property under high humidity is large, and it is better. In addition, the length and width are more preferably 30 or more, and more preferably 90 or more.

In addition, the aspect ratio of the flat inorganic pigment B refers to the value obtained by taking a sample of the particles of the flat inorganic pigment B with an electron microscope and dividing the diameter by the thickness and averaging the 100 particles. The larger the ratio, the greater the flatness of the flat inorganic pigment B.

In the present invention, when the flat inorganic pigment A is mica and the flat inorganic pigment B has an aspect ratio of 10 or more, if the content ratio of the flat inorganic pigment A and the flat inorganic pigment B is flat inorganic pigment A / flat inorganic pigment B = 60 / 40 to 5/95 (solid content ratio), the mica and the flat inorganic pigment B will effectively fill the voids in the barrier coating layer, so the improvement effect of water vapor barrier property and gas barrier property becomes more Large, but better. More preferred is 55/45 to 10/90, and more preferred is 50/50 to 15/85.

In the present invention, in addition to the above-mentioned flat inorganic pigment A and flat inorganic pigment B, two or more kinds may be used alone or in combination of the following: calcium carbonate, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, Inorganic pigments such as silicate, colloidal silica, satin white, and organic pigments such as compact, hollow, or core-shell.

In the present invention, when the barrier coating layer is a single layer, the total amount of the water vapor barrier resin and the gas barrier resin is compared with 100 parts by weight of the total pigment contained in the barrier coating layer based on the dry weight. The preferred range is from 11 parts by weight to 1300 parts by weight.

In addition, when the barrier coating layer is a combination of a water vapor barrier coating layer and a gas barrier coating layer, when the water vapor barrier coating layer contains a pigment, relative to the dry weight, 100 parts by weight of all pigments contained in the water vapor barrier coating layer, the water vapor barrier resin is preferably 10 parts by weight to 300 parts by weight, and more preferably 30 parts by weight to 250 parts by weight. When the gas barrier coating layer contains a pigment, the gas barrier resin is preferably 1 part by weight to 1,000 parts by weight based on 100 parts by weight of the total pigment contained in the gas barrier coating layer. The following.

In addition, in the present invention, when the barrier coating layer contains a pigment, it is preferred that the pigment is added to a water vapor barrier resin and a gas barrier resin, and the pigment is mixed and mixed.

    (Crosslinking agent)    

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

In the present invention, the type of the cross-linking agent is not particularly limited, and in accordance with the types of the water vapor barrier resin and the gas barrier resin contained in the barrier coating layer, 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 oxides Compounds formed by bonding plasmonic substances), amine compounds, amidine compounds, aldehyde compounds, hydroxy acids, and the like. From the standpoint 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 and viscosity of the coatable coating liquid, but it is preferably 1 part by weight relative to 100 parts by weight of the pigment. It is more preferably 10 parts by weight or less, and 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 liquid increases significantly, and coating may become difficult.

In the present invention, when a crosslinking agent is added to the coating liquid for a barrier coating layer, it is preferred to add the crosslinking agent after dissolving it in a polar solvent such as ammonia. When the cross-linking agent is dissolved in a polar solvent, a bond is formed between the cross-linking agent and the polar solvent. Therefore, even if it is added to the coating liquid, cross-linking with a water vapor barrier resin or a gas barrier resin does not occur immediately. Therefore, the thickening of the coating liquid can be suppressed. In this case, 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 or a gas barrier resin occurs to form a dense barrier. Coating.

    (Water Repellent)    

In the present invention, in order to improve the water vapor barrier property, a water repellent agent may be contained in the 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 amount of the water-repellent agent is not particularly limited, but the amount of the water-repellent agent is preferably: based on the dry weight, the water-repellent agent is 1 part by weight relative to 100 parts by weight of the water vapor barrier resin. Above 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 the paper substrate, the water vapor barrier coating layer, and the gas barrier coating layer are laminated in this order and the water vapor barrier coating layer contains a water-repellent agent, it becomes It is difficult to form the gas barrier coating layer uniformly, so there is a possibility that the gas barrier property is lowered.

In addition, in the present invention, when the paper substrate, the water vapor barrier coating layer, and the gas barrier coating layer are laminated in this order, the water vapor barrier property is improved and the gas barrier coating layer is in close contact with each other. From the viewpoint of performance, 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 or less, and it is more effective if it is 15 mN / m or more and 50 mN / m or less.

    (Surfactant)    

In the present invention, a surfactant may be contained in the barrier coating layer. Especially when the paper substrate, the water vapor barrier coating layer, and the gas barrier coating layer are laminated in this order, if a surfactant is contained in the gas barrier coating layer, the water vapor barrier coating can be improved. The adhesion of the layer is better.

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, an acetylene glycol-based surfactant having a large leveling effect in improving the leveling property of the coating liquid for a gas barrier coating layer is preferably used. In addition, when the leveling property of the coating liquid for the gas barrier coating layer is improved, the uniformity of the gas barrier coating layer is improved, so the gas barrier property is improved.

In the present invention, when the paper substrate, the water vapor barrier coating layer, and the gas barrier coating layer are laminated in this order, from the viewpoint of the adhesion between the water vapor barrier coating layer and the gas barrier coating layer It is preferable to adjust the surface tension of the coating liquid for a gas barrier coating layer to 10 mN / m or more and 60 mN / m or less. For more effective effects, it is preferably adjusted to 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 coating liquid was set to ± 20 mN / m.

    (Auxiliaries)    

In the barrier coating layer of the present invention, in addition to the above-mentioned water vapor barrier resin, gas barrier resin, other resins, pigments, water repellents, and surfactants, dispersants, tackifiers, Various additives commonly used, such as water-retaining agents, defoamers, water-resistant agents, dyes, and fluorescent dyes.

    (Coating of barrier coating layer)    

In the present invention, the method for applying the 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 barrier coating layer, a general method such as 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.

In the present invention, when the barrier coating layer is a single layer, the coating amount of the barrier coating layer is preferably 3.2 g / m ² or more and 70 g / m ² or less, and more preferably 5.2 g in dry weight. / m ² or more and 60 g / m ² or less, and more preferably 7.2 g / m ² or more and 40 g / m ² or less.

In addition, when the barrier coating layer is a combination of a water vapor barrier coating layer and a gas barrier coating layer, the coating amount of the water vapor barrier coating layer is preferably 3.0 g in dry weight. / m ² or more and 50 g / m ² or less, more preferably 5.0 g / m ² or more and 40 g / m ² or less, and still more preferably 7.0 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 a gas barrier layer may be used. In cases where penetration into the paper substrate does not provide sufficient gas barrier properties. On the other hand, if it is more than 50 g / m ² , the drying load during coating becomes large.

Moreover, 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.

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 layer, so that 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.

Furthermore, 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.

    (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. 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 for the pigment, two or more kinds can be used alone or in combination of the following: kaolin, clay, engineering kaolin, exfoliated clay, heavy calcium carbonate, light calcium carbonate, mica, talc, titanium dioxide, barium sulfate, sulfuric acid Inorganic pigments such as calcium, zinc oxide, silicic acid, silicate, colloidal silica, satin white, and 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 .

    (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 barrier coating layer of the paper barrier material caused by moisture in the air or the friction, cracking, etc. of the barrier coating layer, and can impart more resistance to the paper barrier material. Further 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 can be imparted. 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 preferred to have a protective layer on at least the side of the 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 50g / m ² ˙day; (2) Oxygen penetration at a temperature of 23 ℃ and a relative humidity of 0% The degree is below 2ml / m ² ˙day˙atm; (3) The oxygen permeability at a temperature of 23 ° C and a relative humidity of 85% is below 3ml / m ² ˙day˙atm.

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) Aspect ratio of the flat inorganic pigment: measured by the method described above.

    [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 with starch (manufactured by Sunus Corporation, Rocorns (transliteration)) having a solid content concentration of 3% so that both sides would be 1.0 g / m ^{2 in} total, dried, and 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)    

A mica slurry (manufactured by TOPY Industries, Ltd., product name: NTS-10, aspect ratio: 1500, and solid content concentration of 10%) was prepared as a flat inorganic pigment A. In addition, kaolin (made by IMERYS, product name: BARRISURF HX, aspect ratio: 100) was added as a dispersant sodium polyacrylate (0.2 parts with respect to inorganic pigments), and dispersed in a Cellier mixer to adjust the solid content concentration 60% kaolin paste as flat inorganic pigment B.

The above-mentioned mica slurry and kaolin slurry were mixed such that mica was 50 parts (solid content) and kaolin was 50 parts (solid content), and 100 parts (solid content) of the pigment was used to prevent water vapor from blocking. A styrene / acrylic copolymer emulsion of a barrier resin (manufactured by Saiden Chemical Co., Ltd., product name: Saibinol X-511-374E) is formulated so as to be 100 parts (solid content), and the pigment is added to 100 parts of the pigment so that Paraffin-based water-repellent agent (manufactured by Marubeni Chemical Co., Ltd., product name: MYE-35G, wax-containing polyethylene emulsion) was prepared in such a way that it was 100 parts (solid content) to obtain a water vapor barrier coating with a solid concentration of 22% Coating solution A1 for layers.

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

An aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., product name: PVA117) was prepared as a gas barrier resin so that the solid content concentration became 10%. In the obtained polyvinyl alcohol aqueous solution, 100 parts of polyvinyl alcohol (solid form Parts) to prepare a polysiloxane-based surfactant (manufactured by SAN NOPCO, product name: SN WET 125) to 1 part (solid content) to obtain a coating liquid B1 for a gas barrier coating layer.

    (Manufacture of paper barrier materials)    

On the obtained paper substrate, the coating liquid A1 for the water vapor barrier coating layer was coated on a single side with a doctor blade coater so that the coating amount was 15 g / m ² on a dry weight basis. After drying, A coating liquid B1 for a gas barrier coating layer was applied thereon such that the coating amount was 5.0 g / m ² on a dry weight basis, and a single-sided coating was performed using a roll coater and dried to obtain a paper barrier material. .

    [Example 2]    

In addition to using kaolin (manufactured by IMERYS Corporation, product name: Capim CC, aspect ratio: 15) instead of kaolin (manufactured by IMERYS Corporation, product name: BARRISURF HX, coating ratio A1 for water vapor barrier coating layer), aspect ratio: Except for 100), a paper barrier material was obtained in the same manner as in Example 1.

    [Example 3]    

Add sodium pyrophosphate (0.4 parts with respect to inorganic pigments) as a dispersant to bentonite (manufactured by KUNIMINE Industries, product name: KUNIPIA F, aspect ratio: 400), and disperse with a Cellier mixer to adjust the solid content concentration of 15 % Bentonite slurry as flat inorganic pigment B.

In addition to using the above-mentioned bentonite slurry 50 parts (solid content) instead of the kaolin slurry (manufactured by IMERYS, product name: BARRISURF HX, aspect ratio: 100) of the water vapor barrier coating layer A1, 50 parts (solid) Except for parts), a paper barrier material was obtained in the same manner as in Example 1.

    [Example 4]         (Preparation of coating liquid A2 for water vapor barrier coating layer)    

A mica slurry (manufactured by TOPY Industries, Ltd., product name: NTS-10, aspect ratio: 1500, and solid content concentration of 10%) was prepared as a flat inorganic pigment A. In addition, kaolin (made by IMERYS, product name: BARRISURF HX, aspect ratio: 100) was added as a dispersant sodium polyacrylate (0.2 parts with respect to inorganic pigments), and dispersed in a Cellier mixer to adjust the solid content concentration 60% kaolin paste as flat inorganic pigment B. In addition, a heavy calcium carbonate slurry (manufactured by FIMATEC Industries, product name: FMT-90, solid content concentration of 60%) was prepared as another inorganic pigment.

The above mica slurry, kaolin slurry, and heavy calcium carbonate slurry were prepared so that mica became 54 parts (solid content), kaolin became 36 parts (solid content), and heavy calcium carbonate became 10 parts (solid content). Mix and make 100 parts (solid content) of the pigment so that the styrene / acrylic copolymer emulsion (manufactured by Saiden Chemical Co., Ltd., product name: Saibinol X-511-374E) as a water vapor barrier resin becomes 100 parts (Solid content), and 100 parts of the pigment so that the paraffin-based water repellent (manufactured by Marubeni Chemical Co., Ltd., product name: MYE-35G, wax-containing polyethylene emulsion) is 100 parts (solid) The coating solution A2 for a water vapor barrier coating layer having a solid content concentration of 22% was obtained by formulating.

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 5]    

Except that the mixing ratio of the mica and the kaolin of the coating liquid A1 for the water vapor barrier coating layer was mixed such that the mica became 60 parts (solid content) and the kaolin became 40 parts (solid content), it was mixed with the examples. 1 In the same manner, a paper barrier material was obtained.

    [Example 6]    

Except that the mixing ratio of the mica and the kaolin of the coating liquid A1 for the water vapor barrier coating layer was mixed such that the mica was 30 parts (solid content) and the kaolin was 70 parts (solid content), it was mixed with the examples. 1 In the same manner, a paper barrier material was obtained.

    [Example 7]    

Add sodium pyrophosphate (0.4 parts with respect to inorganic pigments) as a dispersant to bentonite (manufactured by KUNIMINE Industries, product name: KUNIPIAF, aspect ratio: 400), and disperse with a Cellier mixer to adjust the solid content concentration to 15% Bentonite slurry as a flat inorganic pigment A.

In addition to using 50 parts of the above-mentioned bentonite slurry (solid content) instead of the mica slurry of the coating liquid A1 for the water vapor barrier coating layer (manufactured by TOPY Industries, product name: NTS-10, aspect ratio: 1500, solid content) A paper barrier material was obtained in the same manner as in Example 1 except that the concentration was 10%) and 50 parts (solid content).

    [Comparative Example 1]    

Except using heavy calcium carbonate (manufactured by FIMATEC Industries, product name: FMT-90) instead of kaolin (manufactured by IMERYS, product name: BARRISURF HX, aspect ratio: 100) of the coating liquid A1 for water vapor barrier coatings. Except for), a paper barrier material was obtained in the same manner as in Example 1.

As shown in Table 1, compared with the paper barrier material of Comparative Example 1, the paper barrier materials of Examples 1 to 7 are superior in water vapor barrier properties and gas barrier properties.

Claims (12)

    A paper barrier material has at least one pigment-containing barrier coating layer on a paper substrate, wherein the barrier coating layer contains, relative to all pigments of the barrier coating layer, 50% by weight or more of at least two types of flat inorganic pigment A and flat inorganic pigment B.         The paper barrier material according to item 1 of the scope of patent application, wherein the flat inorganic pigment A is mica, and the aspect ratio of the flat inorganic pigment B is 10 or more.         The paper barrier material according to item 1 or item 2 of the patent application scope, wherein the flat inorganic pigment B is kaolin.         The paper barrier material according to any one of claims 1 to 3, wherein the aspect ratio of the flat inorganic pigment B is 30 or more.         The paper barrier material according to any one of claims 1 to 4, wherein the barrier coating layer has water vapor barrier property and / or gas barrier property.         The paper barrier material according to item 5 of the scope of patent application, wherein the barrier coating layer has at least water vapor barrier property.         A paper barrier material is further provided with a protective layer on at least one side of the paper barrier material according to any one of claims 1 to 6.         A packaging material is a paper barrier material described in any one of claims 1 to 7 of the scope of patent application.         A bag is made of a paper barrier material as described in any one of claims 1 to 7 of the scope of patent application.         A pallet is a paper barrier material described in any one of the first to seventh scope of the patent application.         A cup is made of a paper barrier material as described in any one of claims 1 to 7 of the scope of patent application.         A liquid paper container using the paper barrier material described in any one of claims 1 to 7 of the scope of patent application.