TWI811322B - 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 little environmental impact.

A paper barrier material of the present invention has at least a water vapor barrier coating layer on a paper substrate, wherein the water vapor barrier coating layer contains a water vapor barrier resin, and the oil absorption degree of the paper substrate is 50 seconds or more. The water vapor barrier coating layer further contains a pigment, wherein the content of the water vapor barrier resin relative to 100 parts by weight of the pigment is preferably 30 parts by weight or more and 350 parts in weight or less in terms of absolute dry weight.

Description

paper barrier material

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

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

Conventionally, in order to provide gas barrier properties to paper packaging materials, the following methods have been mainly used: on the paper base material (base paper), metal foil composed of metal such as aluminum, metal vapor-deposited film, polyvinyl alcohol , ethylene-vinyl alcohol copolymer, polyvinylene chloride, polyacrylonitrile and other resin films, or films coated with these resins, or evaporated inorganic oxides such as silicon oxide or aluminum oxide The resulting ceramic vapor-deposited film is used as a gas barrier layer and is extruded, laminated or bonded to the paper base material (base paper).

As for paper packaging materials provided with gas barrier properties other than those mentioned above, paper gas barrier materials having a gas barrier layer composed of a water-soluble polymer and an inorganic layered compound have been disclosed (Patent Document 1, 2) Paper-made gas barrier materials (Patent Document 2), etc., in which a barrier layer composed of a specific vinyl alcohol polymer is provided on the coating layer.

In addition, a barrier material with added gas barrier properties and water vapor barrier properties has been disclosed (Patent Document 3).

[Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2009-184138

[Patent Document 2] Japanese Patent Application Publication No. 2003-094574

[Patent Document 3] Japanese Patent No. 5331265

However, in the method of extruding, laminating or bonding the above-mentioned films to the paper base material (base paper), these films are not sustainable raw materials, and if they are incinerated, there will be problems with residues and carbon dioxide emissions. If it is buried, it will become marine waste because it is not biodegradable, and there will be a problem of heavy environmental load.

In addition, when paper is used as the base material of the barrier material, since the paper, unlike the film, has low smoothness and high moisture penetration, it is difficult to effectively and uniformly apply a coating liquid with barrier properties.

Therefore, the object of the present invention is to provide a paper barrier material, which is a paper base material that is effectively and uniformly coated with a barrier coating liquid, has excellent water vapor barrier properties, and has low environmental load. .

The present invention provides the following [1] to [9].

[1] A paper barrier material having at least a water vapor barrier coating layer on a paper base material, wherein the water vapor barrier coating layer contains a water vapor barrier resin, and a drop of the paper base material Oil absorption is over 50 seconds.

[2] The paper barrier material as described in [1], wherein the water vapor barrier coating layer further contains a pigment, and the content of the water vapor barrier resin is based on absolute dryness relative to 100 parts by weight of the pigment. The weight is 30 parts by weight or more and 350 parts by weight or less.

[3] The paper barrier material as described in [1] or [2] further has a gas barrier coating layer on the aforementioned paper base material.

[4] A paper barrier material further having a protective layer on at least one side of the paper barrier material described in any one of [1] to [3].

[5] A packaging material using the paper barrier material described in any one of [1] to [4].

[6] A bag using the paper barrier material described in any one of [1] to [4].

[7] A pallet using the paper barrier material described in any one of [1] to [4].

[8] A cup using the paper barrier material described in any one of [1] to [4].

[9] A liquid paper container using the paper barrier material described in any one of [1] to [4].

According to the present invention, a paper barrier material can be provided, in which a paper base material is effectively and uniformly coated with a coating liquid having barrier properties, and has excellent water vapor barrier properties. Furthermore, by providing a gas barrier coating layer on the paper base material, a paper barrier material with excellent gas barrier properties and water vapor barrier properties can be provided.

In addition, since the main component is paper which is a biomass material that is a sustainable raw material, from the perspective of carbon neutrality, it can reduce the cost from production to disposal compared with films derived from fossil resources. The amount of carbon dioxide emitted is reduced, and because it is biodegradable, it is less likely to cause environmental pollution even when discarded, 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 base material (hereinafter sometimes referred to as "base paper"). The paper barrier material of the present invention can also be provided with a gas barrier coating layer on the paper base material. In this case, the order in which each layer is constructed is not particularly limited, but it is preferable that the paper base material, 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 a coating liquid mainly using water as a medium using various coating devices and drying it.

The reason why a paper barrier material having a water vapor barrier coating layer and a gas barrier coating layer in this order has both excellent water vapor barrier properties and gas barrier properties is speculated as follows.

As for the gas barrier resin used in the gas barrier coating layer, as exemplified below, it is generally a water-soluble polymer or a water-dispersible polymer. When it is sequentially provided on the paper base material, Gas barrier coatings and water vapor barrier coatings may contain water-soluble polymers or have high water dispersibility due to moisture in the paper base material or moisture in the air that penetrates through the paper base material. The gas barrier coating layer of polymers such as molecule is prone to deterioration. On the other hand, if a water vapor barrier coating layer containing a resin with good water resistance and a gas barrier coating layer are sequentially provided on the paper base material, the water vapor barrier coating layer can effectively inhibit the The influence (deterioration) of moisture in the material on the gas barrier coating layer. Therefore, especially the paper barrier material having a water vapor barrier coating layer and a gas barrier coating layer in sequence has good water vapor barrier properties and gas barrier properties.

(paper base material)

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

For pulp, chemical pulps such as broadleaf bleached kraft pulp (LBKP), coniferous bleached kraft pulp (NBKP), broadleaf unbleached kraft pulp (LUKP), coniferous unbleached kraft pulp (NUKP), sulfite pulp, stone ground pulp, etc. can be used. Mechanical pulps such as paper pulp and thermomechanical pulp, wood fibers such as deinked pulp and waste paper pulp, non-wood fibers obtained from kenaf, bamboo, hemp, etc., polyester resin fibers such as polyethylene terephthalate, polyethylene terephthalate, etc. Polyolefin-based resin fibers such as propylene 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, synthetic resin filler, etc. can be used. In addition, internal additives for papermaking such as aluminum sulfate, various anionic or cationic, nonionic or amphoteric retention aids, drainage enhancers, paper strength enhancers, and internal sizing agents may be used as needed. Furthermore, dyes, fluorescent whitening agents, pH adjusters, defoaming agents, pitch control agents, slime control agents, etc. may also be added as needed.

The manufacturing (papermaking) method of the paper base material is not particularly limited. Known fourdrinier forming machines, ontop hybrid former machines, gap former machines, and Yankee paper machines can be used. Yankee machine), etc., use acid papermaking, neutral papermaking, and alkaline papermaking methods to make paper to produce paper substrates. In addition, the paper base material may be one layer or may be composed of two or more layers.

Furthermore, the surface of the paper substrate can be treated with various chemical agents. Examples of chemical agents used include oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, polyacrylamide, polyvinyl alcohol, surface sizing agents, water-resistant agents, water-retaining agents, and thickening agents. agents, lubricants, etc., which can be used alone or in a mixture of two or more.

Furthermore, these various chemical agents and pigments can be used together. The following pigments can be used alone or in a mixture of two or more: kaolin, clay, engineered kaolin, exfoliated clay, heavy calcium carbonate, light calcium carbonate, mica, talc, titanium dioxide, barium sulfate, sulfuric acid Calcium, zinc oxide, silicic acid, silicate, colloidal silicon oxide, satin white and other inorganic pigments and dense, hollow, or core-shell type organic pigments, etc.

The surface treatment method of the paper base material is not particularly limited, but a rod metering size press, a pool size press, a gate roll coater, a sprayer, Known coating devices such as blade coaters and curtain coaters are available.

Examples of the paper substrate obtained in this way 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 well-known ones such as board, liner, etc.

(drip oil absorption)

The dropwise oil absorption of the paper base material of the present invention is 50 seconds or more, preferably 100 seconds or more. If the water vapor barrier property of the paper barrier material of the present invention is to be improved, a certain amount of water vapor barrier resin must be contained. Therefore, in the water vapor barrier coating layer, if the pigment composition and When comparing the resin components, the resin component tends to increase. There are many lipophilic resins among the water vapor barrier resins. In order to prevent them from penetrating into the paper base material, the oil absorption degree of the paper base material is set to 50 seconds or more. If the droplet oil absorption of the paper base material is 50 seconds or more, the water vapor barrier resin component will easily stay on the surface of the paper, and it will be easy to form a uniform film that effectively exhibits the water vapor barrier property. As a result, good water vapor barrier properties are obtained. In the present invention, the droplet oil absorption of the paper base material can be adjusted by the above-mentioned surface treatment conditions and the amount of internal fillers and internal additives.

(wet tensile strength)

Since the paper base material of the present invention is coated with a coating liquid that mainly uses water as the medium, the strength of the paper base material when wetted by water is preferably above a certain level. Therefore, the wet tensile strength in the papermaking direction (MD) is preferably 300 N/m or more.

(base weigh)

The paper base material of the present invention can be set to the most appropriate basis weight according to the purpose, but it is generally about 30g/ ^m2 to 600g/ ^m2 , and 30g/ ^m2 to 500g/ ^m2 is mostly used.

(barrier coating)

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

(Water Vapor Barrier Coating)

In the present invention, as for the water vapor barrier resin contained in the water vapor barrier coating layer, the following can be used alone or in mixture of two or more types: water-soluble or water-soluble resin having water vapor barrier properties. Dispersible water-based resins: styrene/butadiene, styrene/acrylic, ethylene/vinyl acetate, paraffin (WAX), polyester resin, butadiene/methyl methacrylate, vinyl acetate / various copolymers such as butyl acrylate series, synthetic adhesives such as maleic anhydride copolymers, acrylic acid/methyl methacrylate series copolymers, or paraffin wax (WAX) blended into synthetic adhesives, etc. In the present invention, it is preferable to mix and use two or more types.

In addition, in order to improve the adhesion between the water vapor barrier coating layer and the paper base material, it is preferable to contain both a water-dispersible resin and a water-soluble resin.

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

In the present invention, in the composition having a water vapor barrier coating layer and a 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 Pigments are included in the water vapor barrier coating.

As for pigments, the following can be used alone or in a mixture of two or more types: kaolin, clay, engineered kaolin, exfoliated clay, mica, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate , colloidal silicon oxide, satin white and other inorganic pigments, and dense, hollow, or core-shell type organic pigments, etc.

Among these pigments, inorganic pigments such as flat kaolin, talc, clay, mica, etc. are preferred from the viewpoint of improving water vapor barrier properties and inhibiting the penetration of the gas barrier coating layer, and kaolin is more preferred. , mica. In addition, it is preferable to use inorganic materials having a volume 50% 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, either alone or in a mixture of two or more types. Pigments. When the average particle diameter or aspect ratio of the inorganic pigment used is smaller than the above range, the number of detours of water vapor in the water vapor barrier coating layer is reduced and the moving distance is shortened. As a result, water vapor will be reduced. The effect of improving vapor barrier properties becomes smaller.

In the present invention, when the water vapor barrier coating layer contains a pigment, the water vapor barrier resin is preferably contained in a range of 30 to 350 parts by weight based on dry weight relative to 100 parts by weight of the pigment. . More preferably, it is 50 parts by weight or more, and still more preferably, it is 80 parts by weight or more. Moreover, 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 can be added to the water vapor barrier coating layer. The cross-linking agent will undergo a cross-linking reaction with the water vapor barrier resin and water-soluble polymer contained in the water vapor barrier coating layer, so the number of bonds (cross-linking points) in the water vapor barrier coating layer Increase. That is, the water vapor barrier coating layer will have a dense structure and can exhibit good water vapor barrier properties.

In the present invention, the type of cross-linking agent is not particularly limited. The type of the water vapor barrier resin and water-soluble polymer contained in the water vapor barrier coating layer can be appropriately selected and used. Copper, zinc, silver, iron, potassium, sodium, zirconium, aluminum, calcium, barium, magnesium, titanium and other multivalent metals and carbonate ions, sulfate ions, nitrate ions, phosphate ions, silicate ions, nitrogen oxides, boron oxides (compounds bonded by ionic substances), amine compounds, amide compounds, aldehyde compounds, hydroxy acids, etc.

It is preferable to use styrene-based water vapor barrier resins such as styrene/butadiene-based and styrene/acrylic-based that exhibit excellent water vapor barrier properties from the viewpoint of exhibiting cross-linking effects. Polyvalent metal salts are used, and potassium alum is more preferably used.

The amount of the cross-linking agent can be mixed without any particular limitation as long as it is within the range of the paint concentration and paint viscosity that can be applied. However, it is preferable that the cross-linking agent is 1 part by weight or more per 100 parts by weight of the pigment. Parts by weight or less, more preferably 3 parts by weight or more and 5 parts by weight or less. When the amount is less than 1 part by weight, the effect of adding the cross-linking agent may not be fully obtained. In addition, when the amount exceeds 10 parts by weight, the viscosity of the coating increases significantly, making coating difficult.

In the present invention, when adding a cross-linking agent to the paint for a water vapor barrier coating layer, it is preferable to dissolve the cross-linking agent in a polar solvent such as ammonia and then add it to the paint. If the cross-linking agent is dissolved in a polar solvent, a bond will be formed between the cross-linking agent and the polar solvent. Therefore, even if it is added to the paint, the cross-linking reaction with the water vapor barrier resin or water-soluble polymer will not occur immediately. Therefore, the viscosity increase of the paint can be suppressed. It is speculated that in this case, after coating on the paper base material, the polar solvent component is volatilized by drying, and a cross-linking reaction occurs with the water vapor barrier resin and water-soluble polymer, forming a dense water vapor barrier. Barrier coating layer.

In the present invention, in order to improve the water vapor barrier property, a water-repellent agent may also be included in the water vapor barrier coating layer. Examples of the water-repellent agent include paraffin-based water-repellent agents based on alkane compounds, natural oil-based water-repellent agents derived from animals and plants such as palm wax or lanolin, and polysilicone-based water-repellent agents containing polysilicone or polysilicon. Silicone-based water-repellent agents containing oxygen compounds, fluorine-containing water-repellent agents containing fluorine compounds, etc. Among these, from the viewpoint of the ability to exhibit water vapor barrier properties, it is preferable to use a paraffin-based water-repellent agent. Moreover, these water-repellent agents can be used individually or in mixture of 2 or more types.

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, based on the total of 100 parts by weight of the water vapor barrier resin and the water-soluble polymer. In other words, the amount of water-repellent agent is not less than 1 part by weight but not more than 100 parts by weight. If the amount of the water-repellent agent is less than 1 part by weight, the water vapor barrier improvement effect may not be fully 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 form the gas barrier coating layer uniformly, so the gas barrier properties may be reduced. possibility.

In addition, in the present invention, from the perspective of improvement of water vapor barrier properties and adhesion to 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 15mN/m or more and 50mN/m or less, the effect will be more effective.

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, the water vapor barrier coating layer may also use a dispersant, a tackifier, a water-retaining agent, and a water-repellent agent. Agents, defoaming agents, 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 with gas barrier properties.

In the present invention, examples of the water-soluble polymer used in the gas barrier coating layer include polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and ethylene copolymerized polyvinyl alcohol; casein Proteins such as egg white, soy protein, synthetic protein; starches such as oxidized starch, cationized starch, urea phosphated 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 polyvinylene chloride, ethylene vinyl acetate resin, modified polyolefin resin, and the like.

In the present invention, from the viewpoint of improving gas barrier properties, it is preferable that the gas barrier coating layer contains a pigment. As for the pigment used in the gas barrier coating layer, the following can be used alone or in mixture of two or more types: kaolin, clay, engineered kaolin, exfoliated clay, heavy calcium carbonate, light calcium carbonate, mica, Talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silicon oxide, satin white and other inorganic pigments and dense, hollow, or core-shell type organic pigments, etc.

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

When the gas barrier coating contains pigment, gases such as oxygen will bypass the pigment. Therefore, compared with a gas barrier coating layer composed of polymers such as water-soluble polymers or water-dispersible polymers that does not contain pigments, it has better gas barrier properties in high-humidity environments.

In the present invention, the gas barrier coating layer containing an inorganic pigment with an average particle diameter of 5 μm or more and an aspect ratio of 10 or more may further contain a pigment with an average particle diameter of 5 μm or less. By using together a pigment with an average particle diameter of 5 μm or less, the voids in the gas barrier coating layer formed by an inorganic pigment with an average particle diameter of 5 μm or more and an aspect ratio of 10 or more can be reduced, resulting in better performance. Gas barrier properties. That is, when the gas barrier coating layer contains pigments with different average particle diameters, it is estimated that the gas barrier coating layer will be filled with "pigments with small average particle diameters" and "inorganic pigments with large average particle diameters." In the "pores" formed by the pigment, gases such as oxygen will bypass the pigment, so it has a higher gas barrier property than a gas barrier coating layer that does not contain pigments with different average particle sizes.

In the present invention, when an inorganic pigment with an average particle diameter of 5 μm or more and an aspect ratio of 10 or more and a pigment with an average particle diameter of 5 μm or less are used in combination, the inorganic pigment with an average particle diameter of 5 μm or more and an aspect ratio of 10 or more and The blending ratio of pigments with 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 inorganic pigments with 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 gases such as oxygen in the gas barrier coating layer is reduced, and the moving distance is shortened, so the gas may be A situation in which the improvement effect of obstacles becomes smaller. On the other hand, when the amount exceeds the above range, the voids formed by the inorganic pigments with a large average particle diameter in the gas barrier coating layer cannot be fully filled with pigments with an average particle diameter of 5 μm or less, so the gas barrier cannot be seen. Further improvement of barrier properties.

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

In the present invention, when the gas barrier coating layer contains a pigment, the blending ratio of the pigment, water-soluble polymer and 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 properties may be reduced.

Furthermore, in the present invention, when blending a pigment with a water-soluble polymer or a water-dispersible polymer, it is preferable to add and mix the pigment in a slurry form.

In the present invention, a cross-linking agent represented by a polyvalent metal salt or the like can be added to the gas barrier coating layer. The cross-linking agent will undergo a cross-linking reaction with water-soluble polymers, water-dispersible polymers and other polymers contained in the gas barrier coating layer, so the number of bonds (cross-linking points) in the gas barrier coating layer will increase. In other words, the gas barrier coating layer will have a dense structure and can exhibit good gas barrier properties.

In the present invention, the type of cross-linking agent is not particularly limited. Polyvalent metal salts ( It is composed of copper, zinc, silver, iron, potassium, sodium, zirconium, aluminum, calcium, barium, magnesium, titanium and other multivalent metals and carbonate ions, sulfate ions, nitrate ions, phosphate ions, silicate ions, nitrogen oxides, boron Compounds bonded with ionic substances such as oxides), amine compounds, amide compounds, aldehyde compounds, hydroxy acids, etc. In addition, from the viewpoint of expressing the cross-linking effect, it is preferable to use a polyvalent metal salt, and more preferably, potassium alum is used.

The amount of the cross-linking agent can be mixed without any particular limitation as long as it is within the range of the paint concentration and paint viscosity that can be applied. However, it is preferable that the cross-linking agent is 1 part by weight or more per 100 parts by weight of the pigment. Parts by weight or less, more preferably 3 parts by weight or more and 5 parts by weight or less. When the amount is less than 1 part by weight, the effect of adding the cross-linking agent may not be fully obtained. In addition, when the amount exceeds 10 parts by weight, the viscosity of the coating increases significantly, making coating difficult.

In the present invention, in order to improve the adhesion with the water vapor barrier coating layer, the gas barrier coating layer may contain a surfactant. There is no limit to the ionic nature of the surfactant. Whether it is anionic surfactant, cationic surfactant, amphoteric surfactant, or nonionic surfactant, any of them can be used alone or in combination of two or more. And use. In addition, specific types include: polysiloxy surfactant, fluorine surfactant, alcohol surfactant, acetylene surfactant having an acetylene group, acetylene glycol having an acetylene group and two hydroxyl groups Surfactant, alkyl sulfonic acid surfactant with alkyl group and sulfonic acid, ester surfactant, amide surfactant, amine surfactant, alkyl ether surfactant, phenyl surfactant Ether surfactants, sulfate ester surfactants, phenol surfactants, etc. Among these, it is preferable to use an acetylene glycol surfactant which has a large effect of improving the leveling property of the paint. In addition, when the leveling properties of the coating are improved, the uniformity of the gas barrier coating will be improved, so the gas barrier properties will be improved.

In the present invention, from the viewpoint of adhesion with the water vapor barrier coating layer, the surface tension of the paint for the gas barrier coating layer can be adjusted to 10 mN/m or more and 60 mN/m or less. To achieve a better effect, It is better to adjust it to 15mN/m or more and 50mN/m or less.

Furthermore, from the viewpoint of the adhesion between the water vapor barrier coating layer and the gas barrier coating layer, it is preferable that the gas barrier coating layer be used with respect to the wetting tension on the surface of the water vapor barrier coating layer. The surface tension of the paint was set to ±20mN/m.

In the present invention, in the gas barrier coating layer, in addition to the above-mentioned water-soluble polymers, water-dispersible polymers, pigments, cross-linking agents, and surfactants, dispersants, thickeners, water-retaining agents, Defoaming agents, water resistance agents, dyes, fluorescent dyes and other commonly used additives.

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

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 known coating devices and coating systems. For example, the coating device may include: blade coater, rod coater, roller coater, air knife coater, reverse roller coater, curtain coater, spray coater, sizing press coating Applicator, roller coater, etc. In addition, as for the coating system, a water-based coating mainly using water as the medium is preferred.

As for the method of drying the water vapor barrier coating layer and the gas barrier coating layer, steam heaters, gas heaters, infrared heaters, electric heaters, hot air heaters, microwaves, and drum dryers can be used. and other usual methods.

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 in terms of dry weight, and more preferably is 5 g/m ² or more and 40 g/m ² or less. More preferably, it is set to 7g/ ^m2 or more and 20g/ ^m2 or less. ^When the coating amount of the water vapor barrier coating layer is less than 3 g/m2, it may become difficult for the coating liquid to completely cover the paper base material and sufficient water vapor barrier properties cannot be obtained, or the gas barrier coating may become The coating penetrates into the paper base material and cannot obtain sufficient gas barrier properties. On the other hand, when it exceeds 50g/ ^m2 , 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, it is preferable that the total coating amount of all the water vapor barrier coating layers be within 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 based on dry weight. 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 exceeds 20g/ ^m2 , 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, it is preferable that the total coating amount of all the gas barrier coating layers be within the above range.

(protective layer)

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

Protective layers can also be provided on both sides of the paper barrier material, but it is preferable to have a protective layer on at least the side with the water vapor barrier coating layer. Furthermore, for paper barrier materials that have a water vapor barrier coating layer and a gas barrier coating layer in sequence on a paper base material, if there is a protective layer on the gas barrier coating layer, it can It is preferable to prevent the influence (deterioration) of the water vapor barrier coating layer and the gas barrier coating layer caused by moisture in the air.

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

(resin layer)

As for the resin of the resin layer, it may contain: polyester, polyvinyl alcohol, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, polymethylpentane Polyethylene, polyvinyl chloride, acrylonitrile/butadiene/styrene, acrylonitrile/styrene, polymethyl methacrylate, polyvinylene chloride, polyamide (nylon), polyacetal, polycarbonate, etc. Resins derived from fossil resources, polylactic acid (PLA), esterified starch, cellulose acetate, polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), biopolyethylene, biomass Bio-derived resins such as bio-based polyethylene terephthalate and bio-based polyurethane.

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

In addition, for resins derived from fossil resources and resins derived from biomass, polylactic acid (PLA), esterified starch, cellulose acetate, polybutylene succinate (PBS), polysuccinic acid adipate can be used Butylene glycol (PBSA) and other biodegradable resins, polyethylene, polypropylene, polyester, polyethylene terephthalate, polyamide (nylon), biopolyethylene and other non-biodegradable resins Any resin.

In addition, biodegradable resin refers to a resin that is decomposed into molecular levels by the action of microorganisms and eventually becomes 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 extrusion laminate layers, film lamination layers such as barrier films and vapor-deposited films.

When the resin laminated layer is an extrusion laminated layer, the above-mentioned various resins are laminated on at least one side of the paper barrier material by an extrusion lamination method to form a resin laminated layer. In addition, when the resin laminate layer is a film lamination layer, the above-mentioned various resin films are laminated on at least one side of the paper barrier material by a dry lamination method, a sandwich lamination method, etc. to form a resin laminate. layer.

In the present invention, the film used for the film bonding layer includes films made of the above-mentioned various resins. Among these films, films containing polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylene chloride, polyacrylonitrile and other resins as the main component are preferred. Films made of the above-mentioned various resins are coated with these polyethylene films. Films made of resins such as vinyl alcohol, films made of metal foils containing various metals such as aluminum, laminated to films made of the above-mentioned resins, films made of the above-mentioned resins made of various metals such as aluminum, silicon oxide, and alumina, which are vapor-deposited Barrier films such as evaporated films made of inorganic oxides are more preferably evaporated films. One or more layers of these films can be used depending on the purpose.

(barrier)

The paper barrier material of the present invention preferably has the following barrier properties. In addition, the values of the barrier properties described below are values measured in a state where the above-mentioned protective layer is not formed. The paper barrier material of the present invention still has excellent barrier properties even if it does not use various films or metal foils.

(1) Water vapor penetration is below 200g/m ² ‧day at a temperature of 40±0.5℃ and a relative humidity difference of 90±2%; (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 penetration 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 penetration at a temperature of 23°C and a relative humidity of 0% is 3ml/m ² ‧day‧atm or less.

The paper barrier material of the present invention can be kept as it is, or can be laminated with various general-purpose films, barrier films, aluminum foils, etc. that can be laminated with various resins, etc. to produce foods and the like. Packaging materials used for packaging purposes such as packaging materials, bags, paperware, corrugated boxes, pallets, cups, liquid paper containers, etc., or laminates that can be made into industrial materials and building materials. Among them, packaging materials for packaging such as food, bags, paper containers, corrugated boxes, trays, cups, liquid paper containers, etc. can be suitably used. In particular, flexible packaging materials for food can be particularly suitably used. . In addition, flexible packaging materials refer to packaging materials that are composed of soft materials. Generally speaking, they refer to thin and flexible materials such as paper, film, aluminum foil, etc., which are made singly or laminated together. packaging materials. In addition, in terms of shape, it refers to packaging materials such as bags that maintain a three-dimensional shape by placing the contents.

When the paper barrier material of the present invention is used to make packaging materials for food and the like, especially soft packaging materials, it can be laminated with a heat-sealable resin to improve the sealing properties of the packaging material and protect it. The contents prevent oxidation due to oxygen and deterioration due to moisture, etc., thereby extending the storage period.

In addition, when used to make laminates used in industrial materials and building materials, corrosion and deterioration can be prevented by inhibiting the intrusion of oxygen or moisture. In addition, odor barrier properties can be expected to prevent the leakage of solvent odors. and other effects.

[Example]

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

(Evaluation method)

(1) Drop oil absorption: Use a syringe to drop 1 drop (10 μl) of general diesel (diesel No. 2) onto the sample by its own weight, and measure the time until it penetrates into the sample and the liquid surface gloss disappears.

(2) Water vapor penetration: Measured using a water vapor permeability meter (L80-4000, manufactured by Dr. Lyssy Co., Ltd.) under the conditions of a temperature of 40±0.5°C and a relative humidity difference of 90±2%. In addition, the paper barrier material before providing the protective layer was used for measurement.

(3) Oxygen penetration: Measured using an oxygen penetration rate measuring device (OX-TRAN2/21 manufactured by MOCON) under conditions of 23°C, 0%RH and 23°C, 85%RH. In addition, the paper barrier material before providing the protective layer was used for measurement.

[Example 1]

(Preparation of paper base material 1)

100 parts by weight of 320 ml of Canadian Standard Freeness (CSF) broad-leaved tree kraft pulp (LBKP) was used as the raw material pulp. The raw pulp was paper-made using a Fourdrinier paper machine to obtain paper with a basis weight of 63.0 g/m ² . Next, the obtained paper was coated with starch (Rocorns manufactured by SUNUS Co., Ltd.) prepared to a solid content concentration of 3% so that the total on both sides was 1.0 g/m ² and dried, and a chilled calender was used. ) was smoothed at a speed of 300 min/m and a linear pressure of 50 kgf/cm in one pass to obtain a paper base material 1 with a basis weight of 64.0 g/m ² . The oil absorption degree of paper base material 1 is 100 seconds.

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

To engineering kaolin (BARRISURF HX manufactured by IMERYS, particle diameter 9.0 μm, aspect ratio 80 to 100), sodium polyacrylate (0.2 part relative to the pigment) was added as a dispersant, and dispersed using a Cellier mixer to prepare a solid form Kaolin clay slurry with a concentration of 60%. In the obtained kaolin slurry, the amount of styrene/acrylic copolymer emulsion (manufactured by Saiden Chemical Co., Ltd., X-511-374E) as a water vapor barrier resin was adjusted to 100 parts (solid parts) of the pigment. 100 parts (solid parts) of paraffin-based water-repellent agent (MYE-35G, wax-containing polyethylene emulsion manufactured by Maruyoshi Chemical Co., Ltd.) was prepared to obtain a water vapor barrier with a solid concentration of 45%. Coating liquid A1 for barrier coating layer.

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

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

(Production of paper barrier materials)

On the obtained paper base material 1, the coating liquid A1 for the water vapor barrier coating layer was applied using a blade coater at a coating speed of 300 m/min so that the coating amount became 15 g/m ² on a dry weight basis. After coating and drying one side, apply the coating liquid B1 for the gas barrier coating layer on it so that the coating amount becomes 5.0 g/m ² in terms of dry weight, using a roller coater at a coating speed. Single-sided coating is performed at 300m/min to obtain a paper barrier material.

[Example 2]

(Preparation of Paper Base Material 2)

Canadian standard freeness (CSF) 500ml broadleaf tree kraft pulp (LBKP) and CSF 530ml coniferous tree kraft pulp (NBKP) were prepared at a weight ratio of 80/20 as the raw material pulp. The raw pulp was paper-made using a Fourdrinier paper machine to obtain paper with a basis weight of 59.0 g/m ² . Next, the obtained paper was coated with polyvinyl alcohol (PVA117 manufactured by KURARAY Co., Ltd.) prepared to a solid concentration of 2% so that the total on both sides was 1.0 g/m ² and dried, using a cooling calender at a speed of 300 min/ m, and a linear pressure of 50kgf/cm was used for smoothing in one pass to obtain a paper base material 2 with a basis weight of 60.0g/ ^m2 . The droplet oil absorption of paper base material 2 is 50 seconds.

(Production of paper barrier materials)

A paper barrier material was obtained in the same manner as in Example 1 except that paper base material 2 was used instead of paper base material 1 .

[Example 3]

(Production of paper barrier materials)

In addition to applying the coating liquid A1 for the water vapor barrier coating layer on one side using a blade coater at a coating speed of 300 m/ ^min so that the coating amount becomes 12 g/m2 on a dry weight basis, it is dried. , the 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)

To engineering kaolin (BARRISURF HX manufactured by IMERYS, particle diameter 9.0 μm, aspect ratio 80 to 100), sodium polyacrylate (0.2 part relative to the pigment) was added as a dispersant, and dispersed using a Cellier mixer to prepare a solid form Kaolin clay slurry with a concentration of 60%. In the obtained kaolin slurry, the amount of styrene/acrylic copolymer emulsion (manufactured by Saiden Chemical Co., Ltd., 20 parts (solid parts) of paraffin-based water-repellent agent (MYE-35G, wax-containing polyethylene emulsion manufactured by Maruyoshi Chemical Co., Ltd.) to obtain a water vapor barrier with a solid concentration of 45%. Coating liquid A2 for barrier coating layer.

(Production 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 5]

The same procedure as in Example 1 was performed except that low-density polyethylene (manufactured by Japan Polyethylene Co., Ltd., product name: LC602A) was laminated with a thickness of 30 μm on both sides of the paper barrier material obtained in Example 1 by co-extrusion lamination. Paper barrier materials were obtained in the same way.

[Example 6]

(Preparation of paper base material 3)

100 parts by weight of broadleaf kraft pulp (LBKP) with a Canadian standard freeness (CSF) of 320 ml was used as the raw material pulp. The raw pulp was made into paper using a Fourdrinier papermaking machine to obtain paper with a basis weight of 62.5g/ ^m2 . Next, the obtained paper was coated with starch (Rocorns manufactured by SUNUS Co., Ltd.) prepared to a solid content concentration of 4% so that the total of both sides was 1.5 g/m ² and dried, using a cooling calender at a speed of 300 min/m. Smoothing was performed in one pass with a linear pressure of 50kgf/cm to obtain paper base material 3 with a basis weight of 64.0g/ ^m2 . The oil absorption degree of paper substrate 3 is 150 seconds.

(Production of paper barrier materials)

A paper barrier material was obtained in the same manner as in Example 1 except that paper base material 3 was used instead of paper base material 1 .

[Example 7]

(Preparation of Paper Base Material 4)

Canadian standard freeness (CSF) 500ml broadleaf tree kraft pulp (LBKP) and CSF 530ml coniferous tree kraft pulp (NBKP) were prepared at a weight ratio of 80/20 as the raw material pulp. The raw pulp was made into paper using a Fourdrinier papermaking machine to obtain paper with a basis weight of 58.5g/ ^m2 . Next, polyvinyl alcohol (PVA117 manufactured by KURARAY Co., Ltd.) prepared to a solid concentration of 3% was applied to the obtained paper so that the total on both sides was 1.5 g/m ² and dried, using a cooling calender at a speed of 300 min/ m, and a linear pressure of 50kgf/cm was used for smoothing in one pass to obtain a paper base material 4 with a basis weight of 60.0g/ ^m2 . The oil absorption degree of paper substrate 4 is 80 seconds.

(Production of paper barrier materials)

A paper barrier material was obtained in the same manner as in Example 1 except that paper base material 4 was used instead of paper base material 1 .

[Comparative example 1]

(Preparation of paper base material 5)

100 parts by weight of broadleaf kraft pulp (LBKP) with a Canadian standard freeness (CSF) of 320 ml was used as the raw material pulp. The raw pulp was made into paper using a Fourdrinier papermaking machine to obtain paper with a basis weight of 64.0g/ ^m2 . Secondly, a cooling calender was used for smoothing at a speed of 300 min/m and a linear pressure of 50 kgf/cm in one pass to obtain a paper base material 5 with a basis weight of 64.0 g/m ² . The oil absorption degree of paper substrate 5 is 13 seconds.

(Production of paper barrier materials)

A paper barrier material was obtained in the same manner as in Example 1 except that paper base material 5 was used instead of paper base material 1 .

[Comparative example 2]

(Preparation of Paper Base Material 6)

Canadian standard freeness (CSF) 500ml broadleaf tree kraft pulp (LBKP) and CSF 530ml coniferous tree kraft pulp (NBKP) were prepared in a weight ratio of 80/20 as raw material pulp. The raw pulp was made into paper using a Fourdrinier papermaking machine to obtain paper with a basis weight of 59.5g/ ^m2 . Next, the obtained paper was coated with polyvinyl alcohol (PVA117 manufactured by KURARAY Co., Ltd.) prepared to a solid concentration of 1% so that the total on both sides was 0.5 g/m ² and dried, using a cooling calender at a speed of 300 min/ m, and a linear pressure of 50kgf/cm was used for smoothing in one pass to obtain a paper base material 6 with a basis weight of 60.0g/ ^m2 . The oil absorption degree of paper substrate 6 was 28 seconds.

(Production of paper barrier materials)

A paper barrier material was obtained in the same manner as in Example 1 except that paper base material 6 was used instead of paper base material 1 .

As shown in Table 1, when the droplet oil absorption of the paper substrate is more than 50 seconds, the water vapor barrier property is still better even if the coating amount of the water vapor barrier coating layer is the same. In addition, when the content of the water vapor barrier resin is not less than 30 parts by weight and not more than 350 parts by weight based on absolute dry weight relative to 100 parts by weight of the pigment contained in the water vapor barrier coating layer, even if the water vapor barrier coating layer is Even if the coating amount of the layer is the same, the water vapor barrier property is still better.

Claims (9)

A paper barrier material, which has at least a water vapor barrier coating layer on a paper base material, wherein the water vapor barrier coating layer contains a water vapor barrier resin, and the dropwise oil absorption of the paper base material is 50 seconds or more. The paper-made barrier material described in item 1 of the patent application, wherein the water vapor barrier coating layer further contains a pigment, and the content of the water vapor barrier resin is based on absolute dryness relative to 100 parts by weight of the pigment. The weight is 30 parts by weight or more and 350 parts by weight or less. For example, the paper barrier material described in item 1 or 2 of the patent application further has a gas barrier coating layer on the aforementioned paper base material. 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 items 1 to 3 of the patent application scope. A packaging material using the paper barrier material described in any one of items 1 to 4 of the patent application scope. A bag using the paper barrier material described in any one of items 1 to 4 of the patent application scope. A pallet uses the paper barrier material described in any one of items 1 to 4 of the patent application scope. A cup using the paper barrier material described in any one of items 1 to 4 of the patent application scope. A liquid paper container uses the paper barrier material described in any one of items 1 to 4 of the patent application scope.