Process paper

Abstract

To provide process paper that can prevent evaporation of volatile ingredients during storage or transportation.SOLUTION: Process paper has barrier-coated paper and a release agent layer on at least one surface of the barrier-coated paper, wherein the barrier-coated paper comprises a paper substrate and a gas barrier coating layer on at least one surface, and the paper substrate has a thickness of 50 μm or more and 200 μm or less, a density of 0.5 g / cm3 or more and 1.1 g / cm3 or less, and a dry shrinkage ratio in the CD direction of 0.6% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a process paper used in the production of a resin layer. [Background technology]

[0002] When a liquid resin composition that has been melted or dissolved in a solvent is processed into a film, a casting paper may be used on one side of which the liquid resin composition is cured. This processing is generally carried out continuously, with the liquid resin composition being extruded or coated onto casting paper unwound from a roll, and the liquid resin composition being cured to form a resin layer. A laminate having casting paper and a resin layer is continuously unwound and wound into a roll. Patent Document 1 describes a laminate having a moisture permeability of 200 g / m, in which a release treatment is applied to at least one side of base paper having moisture-proof layers on both sides. 2 A prepreg process paper with a shelf life of 24 hours or less has been proposed.

[0003] A laminate having a casting paper and a resin layer is stored, transported, etc. in a rolled form. Here, this laminate may be required to contain a volatile component in order to impart functionality and maintain subsequent processability, etc. However, casting paper made of ordinary paper does not have barrier properties, and therefore the volatile components gradually evaporate during storage and transport, which can cause problems with product quality. Using casting paper laminated with a film can prevent the volatilization of volatile components, but laminated paper has poor disintegration properties, which causes the problem that used casting paper is poorly recyclable as waste paper raw material. In addition, resin films with barrier properties may be used instead of laminated paper, but resin films are prone to stretching and deformation, which can cause problems such as wrinkles when the product is wound up or removed from the rolled up product. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-220482 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a casting paper that can suppress the evaporation of volatile components during storage, transportation, etc. [Means for solving the problem]

[0006] The means for solving the problems of the present invention are as follows. 1. A barrier coated paper having a release agent layer on at least one surface of the barrier coated paper, The barrier coated paper comprises a paper substrate and a gas barrier coating layer on at least one surface thereof, The paper substrate has a thickness of 50 μm or more and 200 μm or less and a density of 0.5 g / cm 3 More than 1.1g / cm 3 Hereinafter, this refers to a process paper characterized by a drying shrinkage rate in the CD direction of 0.6% or less. 2. The casting paper according to 1., characterized in that the release agent layer, the gas barrier coating layer, and the paper substrate are laminated in this order. 3. The oxygen permeability of the barrier coated paper under conditions of 23°C and 50% RH is 200 ml / m 2 3. The process paper according to 1. or 2., characterized in that it has a viscosity of 1000kJ / day atm or less. 4. The casting paper according to any one of 1. to 3., wherein the paper base material has a longitudinal tensile strength of 5 kN / m or more. 5. The barrier coated paper has a pigment coating layer on at least one side of the paper substrate, The casting paper according to any one of 1. to 4., wherein the release agent layer, the gas barrier coating layer, the pigment coating layer, and the paper base material are laminated in this order. 6. A laminate comprising the process paper according to any one of 1. to 5. above and a resin layer laminated on the process paper. [Effects of the Invention]

[0007] The casting paper of the present invention can prevent volatilization of volatile components even when stored for a long period of time with a resin layer formed thereon. Because the casting paper of the present invention has excellent cushioning properties, the resin layer formed on the casting paper can be prevented from being damaged during storage, transportation, etc. The casting paper of the present invention has excellent dimensional stability, is less likely to stretch even when heated during resin lamination, and is less likely to wrinkle during winding or when the wound product is removed. Because the casting paper of the present invention has excellent disintegration properties, it can be recycled as waste paper raw material. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention relates to a process paper used in the production of a resin layer. The casting paper of the present invention comprises a barrier-coated paper and a release agent layer on at least one surface of the barrier-coated paper, The barrier coated paper comprises a paper substrate and a gas barrier coating layer on at least one surface thereof, The paper base material is 50 μm to 200 μm thick and has a density of 0.5 g / cm 3 More than 1.1g / cm 3 The drying shrinkage rate in the CD direction is 0.6% or less. In this specification, the expression "A to B (A and B are numbers)" means a numerical range including the values ​​of A and B, that is, A or more and B or less.

[0009] (Barrier coated paper) The barrier coated paper used in the present invention comprises a paper base and a gas barrier coating layer on at least one side. The barrier coated paper used in the present invention may comprise gas barrier coating layers on both sides of the paper base, or may comprise a paper base and layers other than the gas barrier coating layer; if other layers are present, their arrangement is not particularly limited.

[0010] (Paper base material) In the present invention, the paper substrate is a sheet made mainly of pulp and further containing fillers and various auxiliary agents as required. Pulp that can be used includes chemical pulps such as bleached hardwood kraft pulp (LBKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), unbleached softwood kraft pulp (NUKP), and sulfite pulp; mechanical pulps such as stone-ground pulp and thermomechanical pulp; wood fibers such as deinked pulp and recycled paper pulp; and non-wood fibers obtained from kenaf, bamboo, hemp, etc., and these can be used alone or in combination of two or more. Among these, chemical pulp made from wood fiber or mechanical pulp is preferred, and chemical pulp made from wood fiber is more preferred, for reasons such as the low likelihood of foreign matter being mixed into the paper base material and the low likelihood of discoloration over time when recycled as recycled paper after use.

[0011] When a filler is used in the paper base material, 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 as needed. In addition, aluminum sulfate and various internal additives such as anionic, cationic, nonionic, or amphoteric retention aids, drainage aids, paper strength agents, and internal sizing agents can be used as needed. Furthermore, auxiliary agents such as dyes, fluorescent whitening agents, pH adjusters, antifoaming agents, pitch control agents, and slime control agents can also be added as needed.

[0012] The method for producing the paper base material (papermaking) is not particularly limited, and the paper base material can be produced by acidic papermaking, neutral papermaking, or alkaline papermaking using a known Fourdrinier former, on-top hybrid former, gap former machine, etc. The paper base material may be composed of one layer, or two or more layers. Furthermore, the surface of the paper substrate can be treated with various chemicals. Examples of chemicals that can be used include oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, polyacrylamide, polyvinyl alcohol, surface sizing agents, water-resistant agents, water-retention agents, thickeners, and lubricants. These can be used alone or in combination of two or more. Furthermore, these various chemicals can be used in combination with pigments. Examples of pigments include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, mica, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, colloidal silica, and satin white, as well as organic pigments such as solid, hollow, and core-shell pigments, which can be used alone or in combination of two or more.

[0013] The method for treating the surface of the paper substrate is not particularly limited, but known coating devices such as a rod metering size press, a pond type size press, a gate roll coater, a spray coater, a blade coater, and a curtain coater can be used. Examples of paper substrates obtained in this manner include various known types such as fine paper, medium-quality paper, coated paper, one-side glossy paper, kraft paper, one-side glossy kraft paper, bleached kraft paper, glassine paper, paperboard, white paperboard, and liner.

[0014] The paper substrate used in the present invention has a thickness of 50 μm or more and 200 μm or less and a density of 0.5 g / cm 3 More than 1.1g / cm 3 A paper substrate having a thickness and density within these ranges has excellent cushioning properties, and therefore can prevent damage to the resin layer, etc., when stored or transported in a rolled form. From the viewpoint of cushioning properties, the thickness of the paper substrate is preferably 70 μm or more, more preferably 80 μm or more, and from the viewpoint of weight reduction, it is preferably 150 μm or less, more preferably 130 μm or less, even more preferably 120 μm or less, even more preferably 110 μm or less, and even more preferably 100 μm or less. From the viewpoint of cushioning properties, the density of the paper substrate is 1.0 g / cm 3 Less than 0.9 g / cm is preferred3 Less than 0.86 g / cm is more preferable. 3 The following is particularly preferred. From the viewpoint of preventing scratches, 0.6 g / cm 3 More than 0.65g / cm is preferable. 3 The above is more preferable.

[0015] The paper base material used in the present invention has a drying shrinkage rate in the CD direction of 0.6% or less. The process paper of the present invention using this paper base material has a drying shrinkage rate in the CD direction of 0.6% or less, which allows for reduced dimensional change when dried by heat. The drying shrinkage rate is the shrinkage rate measured when a 15 mm wide x 100 mm long sample (prepared so that the width direction is the CD direction and the length direction is the MD direction) is conditioned for 2 hours at 23°C and 50% RH and then dried for 1 hour at 105°C, and is calculated as follows: (length of base paper before drying - length of base paper after drying) / length of base paper before drying x 100(%)

[0016] The paper substrate used in the present invention preferably has a highly smooth coated surface in order to form a uniform coated surface. The Oken smoothness of the coated surface of the paper substrate is preferably 10 seconds or more, more preferably 50 seconds or more, and even more preferably 100 seconds or more. Furthermore, when a release agent layer is formed on a paper substrate without a gas barrier layer therebetween, the sizing degree of the surface on which the release agent layer is directly formed is preferably 20 seconds or more, more preferably 50 seconds or more, in order to prevent sinking of the coating liquid for forming the release agent layer.

[0017] The paper substrate used in the present invention preferably has a longitudinal tensile strength of 5 kN / m or more as measured in accordance with JIS P8113. The process paper of the present invention is wound into a roll after a resin layer is formed on the release agent layer, and may be stored as a roll for a long period of time. A paper substrate with a longitudinal tensile strength of 5 kN / m or more is prone to stretching, and when the rolled paper is unwound, the process paper stretches and wrinkles, which may transfer the unevenness of the wrinkles to a resin layer such as a prepreg, or may tear when the process paper is stretched during resin lamination processing. The longitudinal tensile strength of the paper substrate is more preferably 5.5 kN / m or more, and even more preferably 6.0 kN / m or more. There is no particular upper limit, but it is, for example, about 15 kN / m.

[0018] (gas barrier coating layer) The gas barrier coating layer (hereinafter also referred to as the gas barrier layer) contains at least a gas barrier resin, which is a resin that prevents the permeation of gases such as oxygen. Examples of gas barrier resins include water-soluble polymers or water-dispersible polymers, such as polyvinyl alcohol resins (fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, ethylene copolymer polyvinyl alcohol, etc.), proteins (such as casein, soy protein, and synthetic protein), starches (such as oxidized starch, cationized starch, urea phosphate esterified starch, and hydroxyethyl etherified starch), cellulose derivatives (such as carboxymethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose), polyvinylpyrrolidone, and sodium alginate. These can be used alone or in combination of two or more. Among these, from the viewpoint of gas barrier properties, polyvinyl alcohol resins and cellulose derivatives are preferred, polyvinyl alcohol resins are more preferred, polyvinyl alcohol resins having a degree of polymerization of 400 to 1700 are even more preferred, and polyvinyl alcohol resins having a degree of polymerization of 800 to 1400 are even more preferred.

[0019] The gas barrier layer may contain a flat pigment. By flat pigment, we mean a pigment with an aspect ratio of 30 or greater. The flat pigment is not particularly limited as long as it has an aspect ratio of 30 or greater. Examples of flat pigments include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, mica, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, colloidal silica, and satin white, as well as solid, hollow, and core-shell organic pigments, which may be used alone or in combination of two or more. Among these, preferred are pigments with a 50% volume average particle size (D50, hereinafter also referred to as the average particle size) of 3 μm or greater as measured by laser diffraction / scattering and an aspect ratio of 30 or greater, and more preferred are pigments with an average particle size of 5 μm or greater and an aspect ratio of 50 or greater. Examples of measuring devices that use the laser diffraction / scattering method include the particle size distribution measuring device "Partica" manufactured by Horiba Ltd. and the particle size distribution measuring device "MASTER SIZER S" manufactured by Malvern Instruments.

[0020] When a gas barrier layer contains a flat pigment, gases such as oxygen have to bypass the flat pigment, which increases the distance they travel. As a result, a gas barrier layer containing a flat pigment has improved gas barrier properties compared to a gas barrier layer that does not contain a flat pigment, and exhibits excellent gas barrier properties, particularly in high-humidity atmospheres. The amount of flat pigment in the gas barrier layer is preferably 90 parts by mass or less of flat pigment per 100 parts by mass of gas barrier resin, on a dry mass basis. The flat pigment is an optional component of the gas barrier layer and can be omitted (0 parts by mass). By keeping the amount of flat pigment in the gas barrier layer within this range, excellent flex resistance can be exhibited when the casting paper is rolled up, and a decrease in barrier properties can be suppressed. Furthermore, the inclusion of a flat pigment in the gas barrier layer improves adhesion between the gas barrier layer and adjacent layers. A smaller amount of flat pigment improves flex resistance but decreases gas barrier properties. Therefore, the amount of flat pigment can be adjusted depending on the balance between gas barrier properties and flex resistance required for the casting paper; for example, it can be 1 part by mass or more and 80 parts by mass or less per 100 parts by mass of gas barrier resin. In addition to the gas barrier resin and flat pigment described above, the gas barrier layer may contain various commonly used auxiliary agents such as dispersants, thickeners, water retention agents, antifoaming agents, water-resistant agents, dyes, and fluorescent dyes.

[0021] A cross-linking agent, such as a polyvalent metal salt, can be added to the gas barrier layer. The cross-linking agent undergoes a cross-linking reaction with the water-soluble polymer contained in the gas barrier layer, increasing the number of bonds (cross-linking points) in the gas barrier layer. This means that the gas barrier layer has a dense structure, allowing it to exhibit good gas barrier properties. The type of crosslinking agent is not particularly limited, and can be appropriately selected and used depending on the type of water-soluble polymer contained in the gas barrier layer, such as polyvalent metal salts (compounds in which a polyvalent metal such as copper, zinc, silver, iron, potassium, sodium, zirconium, aluminum, calcium, barium, magnesium, or titanium is bonded to an ionic substance such as carbonate ion, sulfate ion, nitrate ion, phosphate ion, silicate ion, nitrogen oxide, or boron oxide), amine compounds, amide compounds, aldehyde compounds, or hydroxy acids. From the viewpoint of exerting a crosslinking effect, it is preferable to use polyvalent metal salts, and it is more preferable to use potassium alum. The amount of crosslinking agent blended is not particularly limited as long as it is within the range of coatable coating concentration and coating viscosity, but preferably the amount of crosslinking agent is 1 part by mass to 10 parts by mass, more preferably 3 parts by mass to 5 parts by mass, per 100 parts by mass of gas barrier resin. If the amount is less than 1 part by mass, the effect of adding the crosslinking agent may not be fully obtained. On the other hand, if the amount is more than 10 parts by mass, the viscosity of the coating may increase significantly, making coating difficult.

[0022] When a gas barrier layer is formed on another coating layer, it is preferable for the gas barrier layer to contain a surfactant, as this improves adhesion between the gas barrier layer and the other coating layer and improves barrier properties. The ionic nature of the surfactant is not limited, and any of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants may be used alone or in combination of two or more. Examples of surfactants include silicone-based surfactants, fluorine-based surfactants, alcohol-based surfactants, acetylene-based surfactants having an acetylene group, acetylene diol-based surfactants having an acetylene group and two hydroxyl groups, alkylsulfonic acid-based surfactants having an alkyl group and sulfonic acid, ester-based surfactants, amide-based surfactants, amine-based surfactants, alkyl ether-based surfactants, phenyl ether-based surfactants, sulfate ester-based surfactants, and phenol-based surfactants. Among these, acetylene diol-based surfactants are preferred, as they have a significant effect in improving the leveling properties of the coating material. Improved leveling properties of the coating material improve the uniformity of the gas barrier layer, thereby improving gas barrier properties. When a gas barrier layer is provided on top of another coating layer, the surface tension of the paint for the gas barrier layer is preferably adjusted to 10 mN / m to 60 mN / m, and more preferably 15 mN / m to 50 mN / m, from the viewpoint of adhesion to the other coating layer. Furthermore, from the viewpoint of adhesion between the water vapor barrier layer and the gas barrier layer, it is preferable to adjust the surface tension of the paint for the gas barrier layer to ±20 mN / m relative to the wetting tension of the surface of the other coating layer.

[0023] (other layers) The barrier coated paper of the present invention can also have other layers. Examples of other layers include a water vapor barrier layer, a water-resistant layer, an oil-resistant layer, a pigment coating layer, and a protective layer, and one or more of these layers can be formed. However, from the viewpoint of recyclability, it is preferable that the other layer is a coating layer formed by coating.

[0024] When forming a water vapor barrier coating layer (hereinafter also referred to as a water vapor barrier layer), the lamination order of the water vapor barrier layer and the gas barrier layer is not particularly limited. The inclusion of a water vapor barrier layer can prevent a decrease in oxygen permeability due to high humidity, and it is more preferable that a resin layer, a release agent layer, a gas barrier layer, and a water vapor barrier layer be laminated in this order. The presence of the water vapor barrier layer as an outer layer of the gas barrier layer makes it difficult for water vapor to penetrate the gas barrier layer even during storage under high humidity conditions, and deterioration of the gas barrier layer and oxygen permeability can be suppressed.

[0025] (Water vapor barrier coating layer) The water vapor barrier layer contains at least a water vapor barrier resin. As the water vapor barrier resin, styrene-butadiene copolymers, styrene-acrylic copolymers, ethylene-acrylic copolymers, ethylene-vinyl acetate copolymers, butadiene-methyl methacrylate copolymers, vinyl acetate-butyl acrylate copolymers, maleic anhydride copolymers, acrylic acid-methyl methacrylate copolymers, paraffin (wax)-based synthetic adhesives, or adhesives containing paraffin (wax) blended with any of these, can be used alone or in combination of two or more. Of these, it is preferable to use ethylene copolymer synthetic adhesives from the viewpoint of water vapor barrier properties. Examples of the ethylene copolymer that can be used include ethylene-vinyl acetate copolymer, ethylene-unsaturated carboxylic acid copolymer, ethylene-unsaturated carboxylic acid ester copolymer, etc. Examples of the ethylene-unsaturated carboxylic acid copolymer include ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer, and the copolymer may also be an ionomer.

[0026]

[0043] Provided that the water vapor barrier property is not affected, it is also possible to use in combination with the water vapor barrier resin water-soluble polymers such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, ethylene copolymer polyvinyl alcohol, and other polyvinyl alcohols; proteins such as casein, soy protein, and synthetic protein; starches such as oxidized starch, cationized starch, urea phosphate esterified starch, and hydroxyethyl etherified starch; cellulose derivatives such as carboxymethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose; polyvinylpyrrolidone; and sodium alginate.

[0027] The water vapor barrier layer can contain a flat pigment. Examples of flat pigments include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, mica, and talc, as well as solid, hollow, or core-shell organic pigments, which can be used alone or in combination. Among these, kaolin, mica, and talc are preferred, with kaolin being more preferred, from the perspectives of both improving water vapor barrier properties and suppressing penetration of the coating material used to form the gas barrier layer. Furthermore, inorganic pigments with a 50% volume average particle size (D50) of 5 μm or greater, measured by laser diffraction / scattering, and an aspect ratio of 30 or greater are preferably used alone or in combination. If the average particle size or aspect ratio of the inorganic pigment used is smaller than the above range, the number of detours that water vapor molecules take within the water vapor barrier layer decreases, shortening the distance they travel, which may result in a reduced improvement in water vapor barrier properties.

[0028] In the present invention, in order to improve the water vapor barrier property, the water vapor barrier layer can contain a pigment with an average particle size of 5 μm or less, in addition to an inorganic pigment with an average particle size of 5 μm or more and an aspect ratio of 30 or more. Pigments with an average particle size of 5 μm or less include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, colloidal silica, and satin white, as well as solid, hollow, or core-shell organic pigments, which can be used alone or in combination of two or more. Of these pigments, heavy calcium carbonate is preferred.

[0029] By including a pigment with an average particle size of 5 μm or less, the voids in the water vapor barrier layer formed by inorganic pigments with an average particle size of 5 μm or more and an aspect ratio of 30 or more can be more effectively filled, thereby achieving even better water vapor barrier properties. In other words, when pigments with different average particle sizes are included in the water vapor barrier layer, the voids formed by inorganic pigments with larger average particle sizes in the water vapor barrier layer are filled with pigments with smaller average particle sizes, and the water vapor has to travel a longer distance to bypass these pigments, which is presumably why the layer exhibits better water vapor barrier properties than a water vapor barrier layer that does not include pigments with different average particle sizes. When an inorganic pigment with an average particle size of 5 μm or more and an aspect ratio of 30 or more is used in combination with a pigment with an average particle size of 5 μm or less, the blending ratio of the inorganic pigment with an average particle size of 5 μm or more and an aspect ratio of 30 or more to the pigment with an average particle size of 5 μm or less is preferably 50 / 50 to 99 / 1 in dry mass. If the blending ratio of the inorganic pigment with an average particle size of 5 μm or more and an aspect ratio of 30 or more is less than the above range, the number of detours that water vapor takes within the water vapor barrier layer decreases, shortening the distance it travels, which may result in a smaller improvement in water vapor barrier property. On the other hand, if the blending ratio of the inorganic pigment with an average particle size of 5 μm or more and an aspect ratio of 30 or more is more than the above range, the pigment with an average particle size of 5 μm or less cannot sufficiently fill the voids formed by the inorganic pigment with a large average particle size in the water vapor barrier layer, making it difficult to expect improvement in water vapor barrier property.

[0030] When a pigment is contained in the water vapor barrier layer, the blending amount of pigment is preferably in the range of 5 to 200 parts by mass of the total of the water vapor barrier resin and water-soluble polymer per 100 parts by mass of pigment on a dry mass basis, and more preferably 10 to 150 parts by mass of the total of the water vapor barrier resin and water-soluble polymer. Note that the pigment is an optional component of the water vapor barrier layer, and it is possible to not include it (0 part by mass).

[0043] Furthermore, in addition to the water vapor barrier resin, water-soluble polymer, and pigment described above, the water vapor barrier layer may contain various commonly used auxiliary agents such as dispersants, thickeners, water retention agents, antifoaming agents, water-resistant agents, dyes, and fluorescent dyes.

[0031] The water vapor barrier layer can be blended with a crosslinking agent, such as a polyvalent metal salt. The crosslinking agent undergoes a crosslinking reaction with the water vapor barrier resin or water-soluble polymer contained in the water vapor barrier layer, increasing the number of bonds (crosslinking points) in the water vapor barrier layer, giving the water vapor barrier layer a denser structure and enabling it to exhibit better water vapor barrier properties. There are no particular restrictions on the type of crosslinking agent, and one or more of the following may be used depending on the type of water vapor barrier resin and water-soluble polymer contained in the water vapor barrier layer: polyvalent metal salts (compounds in which a polyvalent metal such as copper, zinc, silver, iron, potassium, sodium, zirconium, aluminum, calcium, barium, magnesium, or titanium is bonded to an ionic substance such as carbonate ions, sulfate ions, nitrate ions, phosphate ions, silicate ions, nitrogen oxides, or boron oxides), amine compounds, amide compounds, aldehyde compounds, hydroxy acids, etc. When using styrene-based water vapor barrier resins such as styrene-butadiene and styrene-acrylic resins, which exhibit excellent water vapor barrier properties, it is preferable to use a polyvalent metal salt, and it is more preferable to use potassium alum, from the perspective of exhibiting a crosslinking effect. The amount of crosslinking agent to be added is not particularly limited as long as it is within the range of coatable coating concentration and coating viscosity, but preferably the amount of crosslinking agent is 1 part by mass to 10 parts by mass, more preferably 3 parts by mass to 5 parts by mass, per 100 parts by mass of pigment. If the amount is less than 1 part by mass, the effect of adding the crosslinking agent may not be fully obtained. On the other hand, if the amount is more than 10 parts by mass, the viscosity of the coating may increase significantly, making coating difficult.

[0032] When adding a crosslinking agent to a coating material for a water vapor barrier layer, it is preferable to dissolve the crosslinking agent in a polar solvent such as ammonia and then add it to the coating material. When the crosslinking agent is dissolved in a polar solvent, the crosslinking agent and the polar solvent form a bond, so that adding the crosslinking agent to the coating material does not immediately cause a crosslinking reaction with the water vapor barrier resin or water-soluble polymer, thereby preventing the coating material from thickening. In this case, the polar solvent components volatilize when the coating material is dried after application to the paper substrate, causing a crosslinking reaction with the water vapor barrier resin or water-soluble polymer, forming a dense water vapor barrier layer.

[0033] From the viewpoint of improving the water vapor barrier property, it is preferable that the water vapor barrier layer contain a water repellent. Examples of water repellents include paraffin-based water repellents mainly composed of alkane compounds, natural oil-based water repellents derived from plants and animals such as carnauba and lanoinn, silicone-containing water repellents containing silicone or silicone compounds, and fluorine-containing water repellents containing fluorine compounds, and these can be used alone or in combination of two or more. Of these, it is preferable to use a paraffin-based water repellent from the viewpoint of expressing water vapor barrier performance.

[0034] The amount of water repellent blended is not particularly limited, but is preferably 1 part by mass or more and 100 parts by mass or less of water repellent blended per 100 parts by mass of the combined total of the water vapor barrier resin and water-soluble polymer, in dry mass. If the amount of water repellent blended is less than 1 part by mass, the effect of improving the water vapor barrier property may not be sufficiently obtained. On the other hand, if the amount exceeds 100 parts by mass, it may be difficult to form a uniform gas barrier layer when forming one on the water vapor barrier layer, and the gas barrier property may be reduced. The wetting tension of the surface of the water vapor barrier layer is preferably 10 mN / m or more and 60 mN / m or less, and more preferably 15 mN / m or more and 50 mN / m or less, in order to improve the water vapor barrier property and adhesion to adjacent layers.

[0035] (Pigment coating layer) The barrier coated paper of the present invention preferably has a pigment coating layer on the outermost surface on the side on which the release agent layer will be formed. The pigment coating layer is a layer that prevents the coating liquid used to form the gas barrier layer or release agent layer from sinking into the paper base material, and barrier coated paper with a pigment coating layer allows the gas barrier layer or release agent layer to be formed with a smaller coating weight, and allows these functional layers to exert their full effects.

[0036] The pigment coating layer contains an adhesive and a pigment as a binder. Adhesives that can be used include those conventionally used in coated paper, such as copolymers of styrene-butadiene, styrene-acrylic, ethylene-vinyl acetate, butadiene-methyl methacrylate, and vinyl acetate-butyl acrylate; synthetic adhesives such as polyvinyl alcohol, maleic anhydride copolymers, and acrylic acid-methyl methacrylate copolymers; proteins such as casein, soy protein, and synthetic proteins; starches such as oxidized starch, cationized starch, urea phosphate esterified starch, and hydroxyethyl etherified starch; and cellulose derivatives such as carboxymethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose.

[0037] The pigment coating layer contains pigment particles with an aspect ratio of less than 30. Examples of such particles include inorganic pigments such as calcium carbonate (heavy / light), kaolin, engineered kaolin, clay, delaminated clay, talc, titanium dioxide, aluminum hydroxide, mica, illite, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, colloidal silica, and satin white, as well as solid, hollow, or core-shell organic pigments. One or more of these pigments may be used. The aspect ratio of the pigment contained in the pigment coating layer is preferably 20 or less, more preferably 10 or less, and even more preferably 5 or less. The pigment coating layer may contain flat particles with an aspect ratio of 30 or more as pigment, but the proportion of particles with an aspect ratio of less than 30 to the total particles contained in the pigment coating layer is 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The pigment coating layer preferably contains 10 to 200 parts by mass of adhesive per 100 parts by mass of pigment. The pigment coating layer may also contain various auxiliaries such as cellulose nanofiber (CNF), microfibrillated cellulose (MFC), dispersants, water-resistant agents, lubricants, antifoaming agents, thickeners, water-retaining agents, crosslinking agents, surfactants, preservatives, dyes, and fluorescent dyes, provided that the effects of the present invention are not impaired.

[0038] (Coating method for coating layer) The coating methods for the gas barrier coating layer, water vapor barrier coating layer, pigment coating layer, etc. are not particularly limited, and coating can be performed using known coating equipment and coating systems. Examples of coating equipment include blade coaters, bar coaters, roll coaters, air knife coaters, reverse roll coaters, curtain coaters, gravure coaters, spray coaters, size press coaters, and gate roll coaters. Aqueous coating systems that primarily use water as a medium are preferred. In the present invention, coating can also be performed using an on-machine coater, in which the papermaking machine and coating equipment are integrated. In particular, pigment coating layers can be applied using an on-machine coater. When coating using an off-machine coater, in which the papermaking machine and coating equipment are separate, the base paper is first wound up onto a reel after being made on the papermaking machine, and then the reel is applied to the off-machine coater for coating. However, coating using an on-machine coater eliminates the need to wind up the base paper and then apply it to the coater, thereby improving production efficiency. On the other hand, when coating with an on-machine coater, the coating speed must be synchronized with the papermaking speed of the paper machine, making it more difficult to adjust the coating weight than when coating with an off-machine coater, which does not require synchronization.The pigment coating layer of the present invention has high uniformity and good sealing properties, even when the coating weight is particularly low, so it is easy to achieve the desired performance even when coating with an on-machine coater. On the other hand, compared to the on-machine coater, the off-machine coater offers greater freedom in selecting the coating method, coating amount, and coating liquid formulation. The coating layer can be dried by any conventional method, such as using a steam heater, gas heater, infrared heater, electric heater, hot air heater, microwave, or cylinder dryer.

[0039] The coating weight of the gas barrier layer is 0.2 g / m2 (dry mass) per side. 2 More than 20g / m 2 The coating weight of the gas barrier layer is preferably 0.2 / m or less. 2 If the density is less than 20 g / m, it may be difficult to form a uniform gas barrier layer, and sufficient gas barrier properties may not be obtained. 2 If the amount is more than this, the drying load during coating will increase. The coating amount of the gas barrier layer is 0.5 g / m2 in dry mass per side. 2 More preferably, 0.8 g / m or more 2 More preferably, 10 g / m 2 Less than 5g / m is more preferable. 2 The following is even more preferred:

[0040] The coating weight of the water vapor barrier layer is 3 g / m2 (dry mass) per side. 2 More than 30g / m 2 The coating weight of the water vapor barrier layer is preferably 3 g / m or less. 2 If the coating weight of the water vapor barrier layer is less than 30 g / m, it may be difficult to completely coat the paper substrate with the coating material, resulting in insufficient water vapor barrier properties, or the coating material for the gas barrier layer may penetrate into the paper substrate, preventing the formation of a uniform gas barrier coating layer and resulting in insufficient gas barrier properties. 2 If the amount is more than this, the drying load during coating will increase. The coating amount of the water vapor barrier layer is 5 g / m2 in dry mass per side. 2 More preferably, 7 g / m 2 More preferably, 20 g / m 2 Less than 15 g / m is more preferable. 2 The following is even more preferred:

[0041] The amount of pigment coating is 2g / m2 in dry weight per side. 2 More than 10g / m2 It is preferable that the coating amount is 2 g / m or less. 2 If the coating weight is less than 10 g / m, it may be difficult for the pigment coating layer to prevent the penetration of the coating liquid that forms the release agent layer or gas barrier layer. 2 If the coating weight exceeds 10 ... 2 More preferably, it is 4 g / m or more. 2 More preferably, it is 9 g / m or more. 2 More preferably, it is: Each of the above coating layers may be a single layer or may be configured as two or more layers. When the coating layer is configured as two or more layers, it is preferable that the total coating weight of all the coating layers is within the above range.

[0042] (Release Agent Layer) The release agent layer is formed by coating on at least one surface of the barrier coated paper. From the viewpoint of suppressing the evaporation of volatile components, the release agent layer is preferably provided on the gas barrier layer side of the barrier coated paper, i.e., the release agent layer, gas barrier coating layer, and paper substrate are preferably laminated in this order, and more preferably the release agent layer, gas barrier coating layer, pigment coating layer, and paper substrate are laminated in this order. The release agent can be any material that has low surface energy and can release the resin layer formed thereon, such as a silicone resin, a fluorine-based compound, an aminoalkyd compound, or a polyester resin, without any particular limitations, but it is preferable to use a silicone resin. Examples of the silicone resin used as the release agent include a solventless silicone resin, a solvent-based silicone resin, an aqueous emulsion silicone resin, and a solventless UV-curable silicone resin.

[0043] The method for applying the release agent is not particularly limited, and the release agent can be applied using a known coating device and coating system, such as a blade coater, a bar coater, a roll coater, an air knife coater, a reverse roll coater, a curtain coater, a gravure coater, a spray coater, a size press coater, or a gate roll coater. The release agent layer can be dried by any conventional method, such as using a steam heater, gas heater, infrared heater, electric heater, hot air heater, microwave, or cylinder dryer.

[0044] The coating amount of the release agent layer is 0.2 g / m2 in dry mass per side. 2 More than 3.0g / m 2 The coating weight is preferably 0.2 g / m or less. 2 If the coating weight is less than 3.0 g / m, it becomes difficult to obtain a uniform release agent layer. 2 Above this level, there is almost no improvement in release properties and the effect saturates. The coating amount of the release agent layer is 0.3 g / m2 in dry mass per side. 2 More preferably, 0.4 g / m or more 2 More preferably, it is 2.0 g / m or more. 2 More preferably, it is 1.2 g / m or less. 2 It is even more preferable that:

[0045] (process paper) The writing paper of the present invention has a gas barrier property (oxygen permeability measured under conditions of 23°C and 50% RH) of 200 ml / m 2 It is preferable that the oxygen permeability is 200 ml / m 2 If the oxygen permeability is 100 ml / m or less, the evaporation of volatile components from the resin composition can be appropriately prevented. 2 ·day·atm or less, and the gas barrier property is 10 ml / m 2 It is even more preferable that the temperature is 100°C or less.

[0046] (Laminate) A laminate having a resin layer on the release agent layer of the casting paper of the present invention can be obtained by extruding, coating, or the like, a liquid resin composition melted or dissolved in a solvent onto the release agent layer of the casting paper, and then curing the resulting composition. The laminate can also be formed by laminating the liquid resin composition two or more times to form two or more resin layers, or by laminating paper, resin film, vapor-deposited film, metal foil, protective film, release film (release paper), release film (release paper), etc., and a cord, reinforcing fabric, etc., can also be embedded in the resin layer. The resin layer of the laminate of the present invention is not particularly limited as long as it can be cured on the casting paper, but for example, a layer of carbon fiber reinforced plastics (CFRP) can be formed. The laminate having a resin layer on a release agent layer is finally wound around a paper tube or the like to form a product. It is possible to laminate the casting paper of the present invention on one or both sides and then wind it, or it is also possible to laminate the casting paper of the present invention on one side and ordinary kraft paper or the like on the other side and then wind it, but from the viewpoint of preventing the evaporation of volatile components, it is more preferable to laminate the casting paper of the present invention on both sides and then wind it. The laminate of the present invention may not contain any volatile component, but it is preferable that at least one layer other than the casting paper contains a volatile component. The volatile component is not particularly limited, and examples thereof include functional agents such as insect repellents, mildew inhibitors, disinfectants, rust inhibitors, preservatives, deodorizers, and fragrances, as well as plasticizers and solvents for maintaining the processability of the resin layer. [Example]

[0047] The present invention will be specifically illustrated by the following examples, but the present invention is not limited to the descriptions in the examples. Furthermore, parts by mass in the examples refer to parts by mass on an bone-dry basis unless otherwise specified.

[0048] [Example 1] (Preparation of paper substrate 1) Hardwood bleached kraft pulp (LBKP) with a Canadian standard freeness (CSF) of 550 ml and softwood bleached kraft pulp (NBKP) with a CSF of 600 ml were blended in a mass ratio of 65 / 35 to prepare the raw material pulp. The raw pulp was made into paper, and the resulting paper was coated with 5.0% starch, 0.36% surface sizing agent, and 1.3% polyvinyl alcohol using a size press, dried, and had a basis weight of 85.0 g / m 2 The obtained base paper was subjected to a smoothing treatment using a calendar to obtain paper substrate 1.

[0049] (Preparation of Coating Solution 1 for Gas Barrier Layer) An aqueous solution of polyvinyl alcohol (VC-10, manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.) with a solids concentration of 12% was prepared and used as coating solution 1 for gas barrier layer.

[0050] (Preparation of Barrier Coated Paper 1) Coating solution 1 for gas barrier layer was applied to the back surface of paper substrate 1 in an amount of 4.0 g / m2 in terms of dry mass. 2 The coated paper was then dried to obtain barrier coated paper 1.

[0051] (Preparing Process Paper 1) A silicone release agent (KNS-320A manufactured by Shin-Etsu Silicone Co., Ltd.) was applied to the non-barrier coated surface of barrier coated paper 1 (surface of paper substrate 1) at a dry weight of 1.2 g / m 2 The coating was then dried to obtain casting paper 1 having a release agent layer / (front) paper base 1 (back) / gas barrier layer in this order.

[0052] [Example 2] (Preparation of paper substrate 2) Hardwood bleached kraft pulp (LBKP) with a Canadian standard freeness (CSF) of 560 ml and softwood bleached kraft pulp (NBKP) with a CSF of 510 ml were blended in a mass ratio of 70 / 30 to prepare the raw material pulp. After adding 0.4% of sizing agent and 0.7% of paper strength agent to the raw pulp, paper was made with a basis weight of 59 g / m. 2 I got the paper. Next, the resulting paper was coated with 6.5% starch and 0.2% surface sizing agent using a size press, dried, and had a basis weight of 89 g / m 2 The obtained base paper was subjected to a smoothing treatment using a calendar to obtain paper substrate 2.

[0053] (Preparing process paper 2) A forming paper 2 having a release agent layer / (front) paper base 2 (back) / gas barrier layer in this order was obtained in the same manner as in Example 1, except that paper base 2 was used.

[0054] [Example 3] (Preparation of paper substrate 3) The raw pulp was hardwood bleached kraft pulp (LBKP) with a Canadian standard freeness (CSF) of 460 ml. After adding 1.0% dry strength agent and 0.3% sizing agent to the raw pulp, paper was made with a basis weight of 81.4 g / m 2 I got the paper. Next, the resulting paper was coated with 5.0% starch and 0.36% surface sizing agent using a size press, dried, and had a basis weight of 81.4 g / m 2 The obtained base paper was subjected to a smoothing treatment using a calendar to obtain paper substrate 3.

[0055] (Preparation of process paper 3) A process paper 3 having a release agent layer / (front) paper base 3 (back) / gas barrier layer in this order was obtained in the same manner as in Example 1, except that paper base 3 was used.

[0056] [Example 4] (Creating paper base material 4) Hardwood bleached kraft pulp (LBKP) with a Canadian standard freeness (CSF) of 360 ml and softwood bleached kraft pulp (NBKP) with a CSF of 400 ml were blended in a mass ratio of 60 / 40 to prepare the raw material pulp. The raw pulp was mixed with 0.45% of a dry strength agent based on the absolute dry pulp mass, 0.50% of a sizing agent based on the absolute dry pulp mass, and a cationic polymer retention agent based on the absolute dry pulp mass, before being used for papermaking. Next, a coating solution for the pigment coating layer containing 100 parts of kaolin (aspect ratio 14), 20 parts of styrene-butadiene copolymer latex, 5 parts of starch, and 1 part of lubricant was applied to both sides of the paper using a coater at a total rate of approximately 12 g / m². 2 Coated and dried, basis weight 70g / m 2The obtained base paper was subjected to a smoothing treatment using a calendar to obtain a laminate of the pigment coating layer and the paper substrate 4. (Preparing process paper 4) A casting paper 4 having a release agent layer / pigment coating layer / (front) paper base 4 (back) / pigment coating layer / gas barrier layer in this order was obtained in the same manner as in Example 1, except that paper base 4 was used.

[0057] [Example 5] (Preparation of Coating Solution 1 for Water Vapor Barrier Layer) Sodium polyacrylate was added as a dispersant to engineered kaolin (Imerys, Barisurf HX, average particle size 90 μm, aspect ratio 80-100) (0.2% relative to the pigment) and dispersed in a Serie mixer to prepare a kaolin slurry with a solids concentration of 55%. To the resulting kaolin slurry, 25 parts (solids) of a styrene-acrylic copolymer emulsion (Tg 23°C) and 20 parts (solids) of an ethylene-acrylic copolymer emulsion (Tg 25°C) were blended as water vapor barrier resins per 100 parts (solids) of pigment, yielding Coating Solution 1 for the water vapor barrier layer with a solids concentration of 48.5%.

[0058] (Preparation of barrier coated paper 2) On the backside of the paper substrate 1, the coating solution 1 for the water vapor barrier layer was applied in a dry weight of 12.0 g / m 2 After drying, the coating solution 1 for gas barrier layer was applied on top of it in an amount of 4.0 g / m2 in dry weight. 2 Barrier coated paper 2 was obtained by coating on one side so that the

[0059] (Preparation of process paper 5) A forming paper 5 having a release agent layer / (front) paper base 1 (back) / water vapor barrier layer / gas barrier layer in this order was obtained in the same manner as in Example 1, except that barrier coated paper 2 was used.

[0060] [Example 6] (Creating process sheet 6) Barrier coated paper 1 was used and casting paper 6 was obtained in the same manner as in Example 1, except that a silicone-based release agent was applied to the barrier-coated surface. The casting paper 6 had a release agent layer / gas barrier layer / (back) paper substrate 1 (front) in this order. [Example 7] (Creating process sheet 7) Barrier coated paper 1 was used and casting paper 7 was obtained in the same manner as in Example 6, except that a silicone-based release agent was applied to both the barrier-coated side and the non-barrier-coated side. The casting paper 7 had a release agent layer / gas barrier layer / (back) paper base 1 (front) / release agent layer in this order.

[0061] [Comparative Example 1] (Preparation of process film 1) A silicone release agent was applied to the surface of a 30 μm thick OPP film at a dry mass of 1 g / m 2 The coating was carried out so that the film was coated and dried to obtain a processed film 1.

[0062] Comparative Example 2 (Preparation of process paper 8) A silicone release agent was applied to the surface of the paper substrate 4 at a dry mass of 1 g / m 2 The coating was then dried to obtain a forming paper 8 having a release agent layer / (front) paper substrate 4 (back) in this order.

[0063] (Evaluation method) The paper substrate was evaluated as follows. Basis weight, thickness, density Basis weight: Measured in accordance with JIS P8124. Thickness: Measured in accordance with JIS P8118. Density: Calculated from basis weight and thickness. Smoothness Measurement was performed according to the method of JIS P8155:2010. Size Measurement was carried out according to the method of JIS P8122:2004. Air resistance Measurement was performed using a method conforming to JIS P8117:2009 (Oken type testing machine method). Tensile strength Measurement was carried out according to the method of JIS P8113:2006. Tear strength Measurement was carried out according to the method of JIS P8116:2000. Drying shrinkage rate A sample measuring 15 mm wide and 100 mm long (the width direction is the CD and the length direction is the MD) was cut out from the paper substrate. This sample was conditioned at 23°C and 50% RH for 2 hours, and then dried at 105°C for 1 hour. The drying shrinkage was calculated from the length before and after drying based on the following formula. Drying shrinkage rate = (length of base paper before drying - length of base paper after drying) / length of base paper before drying x 100(%)

[0064] The process paper and process film were evaluated as follows. Disintegration The process paper was immersed in water to a concentration of 2.0% by mass and disintegrated for 60 minutes in a Tappi standard disintegrator, and the degree of disintegration in water was evaluated. [Evaluation criteria] ○: Pulp fibers are dispersed and disintegration is good. ×: Clumps of pulp fibers or bundles of pulp fibers remain, making it impossible to disintegrate.

[0065] Barrier properties (oxygen permeability) The oxygen permeability of the process paper and process film was measured at 23°C and 50% RH using an oxygen permeability measuring device (OX-TRAN2 / 21, manufactured by MOCON).

[0066] ·stretch A prepreg made of resin-impregnated carbon fiber reinforcing agents was laminated onto the release agent-coated surface of each process paper and process film, and then the process paper 8 obtained in Comparative Example 2 was laminated on top of it so that the release agent-coated surface was in contact with the prepreg. The prepreg was cured under heat and pressure at 100°C for 1 hour, and then the process paper and process film were wrapped around a paper tube (3 inches in diameter) and the appearance was visually confirmed. Note that in Example 7, the prepreg was laminated on the release agent-coated surface on the barrier-coated side. [Evaluation criteria] ○: No abnormal appearance occurred. ×: Wrinkles and peeling (peel between the prepreg and the release agent layer) occurred in the casting paper and casting film.

[0067] [Table 1]

Claims

1. A barrier coated paper sheet having a release agent layer on at least one surface of the barrier coated paper sheet, The barrier coated paper comprises a paper substrate and a gas barrier coating layer on at least one surface thereof, The paper substrate has a thickness of 50 μm or more and 200 μm or less and a density of 0.5 g / cm ３ 1.1g / cm or more ３ Hereinafter, the process paper characterized by having a drying shrinkage rate in the CD direction of 0.6% or less.

2. 2. The process paper according to claim 1, wherein the release agent layer, the gas barrier coating layer, and the paper substrate are laminated in this order.

3. The barrier coated paper has an oxygen permeability of 200 ml / m under conditions of 23°C and 50% RH. ２ 2. The process paper according to claim 1, characterized in that it has a viscosity of 1000 psi or less.

4. 2. The process paper according to claim 1, wherein the paper substrate has a longitudinal tensile strength of 5 kN / m or more.

5. the barrier coated paper has a pigment coating layer on at least one side of the paper substrate, 2. The process paper according to claim 1, wherein the release agent layer, the gas barrier coating layer, the pigment coating layer, and the paper base material are laminated in this order.

6. A laminate comprising the process paper according to any one of claims 1 to 5 and a resin layer laminated on the process paper.

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