Barrier paper and industrial or packaging materials

Abstract

To provide barrier paper that is thin and has excellent gas barrier and vapor barrier properties.SOLUTION: This barrier paper comprises: base paper; an undercoat layer stacked on one surface or both surfaces of the base paper; and a coating layer stacked on the surface of the undercoat layer. The density of the base paper on which the undercoat layer is stacked is 0.70 g / cm3 to 1.10 g / cm3, the thickness of the base paper on which the undercoat layer is stacked is 40 μm to 100 μm, the moisture vapor permeability of the base paper on which the undercoat layer is stacked is 800 g / m2 / 24 hr to 2000 g / m2 / 24 hr, the Bekk smoothness of the surface of the undercoat layer is 30 sec. to 300 sec., the coating layer contains a vinylidene chloride copolymer, and the content of the vinylidene chloride copolymer in the coating layer is 50 mass% or more in solid content. The coating amount of the coating layer is preferably 3.0 g / m2 to 15.0 g / m2.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to barrier papers and industrial or packaging materials. [Background technology]

[0002] 2. Description of the Related Art In the packaging of food, agriculture and other industrial fields, etc., packaging materials based on paper and provided with water vapor barrier properties and gas barrier properties have been used in order to prevent deterioration of the quality of the contents.

[0003] As a packaging material having such water vapor barrier properties and gas barrier properties, a paper barrier packaging material in which a water vapor barrier layer and a gas barrier layer are provided on a substrate has been proposed (see Patent Document 1). In the above conventional paper barrier packaging material, the water vapor barrier layer contains 50% to 100% by mass of kaolin with an average particle size of 5 μm or more and an aspect ratio of 10 or more relative to the total pigments, and the gas barrier layer contains a polyvinyl alcohol resin as a binder resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013 / 069788 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the paper barrier packaging material of the above-mentioned conventional technology, moisture proofing and gas barrier properties are imparted by providing coating layers having the characteristics of a moisture proof layer (water vapor barrier layer) and a gas barrier layer, respectively. In this way, when attempting to impart moisture proofing, gas barrier properties, heat sealability, etc. to a paper barrier packaging material, it is necessary to apply coating layers having different functions, such as a moisture proof layer, a gas barrier layer, and a heat seal layer, respectively. In such cases, the amount of coating for each functional layer is added up, and the packaging material tends to become thick. Furthermore, in recent years, there has been a demand for thin packaging materials from the viewpoints of processability, packability, portability, etc.

[0006] The present invention has been made in light of the above circumstances, and has an object to provide a barrier paper that can be used to produce thin industrial materials or packaging materials that have excellent gas barrier properties and water vapor barrier properties. [Means for solving the problem]

[0007] A barrier paper according to one aspect of the present invention comprises a base paper, an undercoat layer laminated on one or both sides of the base paper, and a coating layer laminated on the surface of the undercoat layer, and the density of the base paper on which the undercoat layer is laminated is 0.70 g / cm 3 More than 1.10g / cm 3 the thickness of the base paper on which the undercoat layer is laminated is 40 μm or more and 100 μm or less, and the moisture permeability of the base paper on which the undercoat layer is laminated is 800 g / m 2 ·2000g / m over 24hr 2 the Beck smoothness of the surface of the undercoat layer is 30 seconds or more and 300 seconds or less; the coating layer contains a vinylidene chloride copolymer, and the content of the vinylidene chloride copolymer in the coating layer is 50 mass% or more in terms of solid content. Effect of the Invention

[0008] The present invention makes it possible to provide a thin barrier paper that has excellent gas barrier properties and water vapor barrier properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Description of the embodiment of the present invention] A barrier paper according to one aspect of the present invention comprises a base paper, an undercoat layer laminated on one or both sides of the base paper, and a coating layer laminated on the surface of the undercoat layer, and the density of the base paper on which the undercoat layer is laminated is 0.70 g / cm 3 More than 1.10g / cm 3 the thickness of the base paper on which the undercoat layer is laminated is 40 μm or more and 100 μm or less, and the moisture permeability of the base paper on which the undercoat layer is laminated is 800 g / m 2 ·2000g / m over 24hr 2 the Beck smoothness of the surface of the undercoat layer is 30 seconds or more and 300 seconds or less; the coating layer contains a vinylidene chloride copolymer, and the content of the vinylidene chloride copolymer in the coating layer is 50 mass% or more in terms of solid content.

[0010] The barrier paper has a coating layer that contains a vinylidene chloride copolymer, and the content of the vinylidene chloride copolymer is 50% by mass or more calculated as solid content, so that a single coating layer can provide both gas barrier and water vapor barrier properties. Furthermore, the barrier paper has an undercoat layer, which improves the flatness of the undercoat layer surface and the coatability when laminating the coating layer, thereby improving the properties of the coating layer. It also prevents the coating liquid of the coating layer from penetrating into the base paper, thereby reducing the amount of coating liquid used. The surface of the undercoat layer has a Beck smoothness of 30 seconds or more and 300 seconds or less, and the base paper on which the undercoat layer is laminated has a density of 0.70 g / cm. 3 More than 1.10g / cm 3 The thickness is 40 μm or more and 100 μm or less, and the moisture permeability is 800 g / m 2 ·2000g / m over 24hr 2·24hr or less improves the processing suitability of the barrier paper and the properties of the coating layer laminated on the surface of the undercoat layer. In addition, the coating liquid for the coating layer can be applied uniformly and the penetration into the base paper is suppressed, so that the barrier paper can have high barrier properties with a low coating amount. Therefore, the barrier paper is thin and has excellent gas barrier properties and water vapor barrier properties. "Solid content" refers to components other than solvent. "Density" is measured in accordance with "Paper and paperboard - Test method for thickness and density" described in JIS-P8118 (2014). "Thickness" is measured in accordance with JIS-P8118 (2014). "Moisture permeability" is measured based on condition B in accordance with JIS-Z0208

[1976] Moisture permeability test method for moisture-proof packaging materials [Cup method].

[0011] The coating weight of the above coating layer is 3.0 g / m 2 More than 15.0g / m 2 When the coating weight of the coating layer is within the above range, both the gas barrier property and the water vapor barrier property can be improved.

[0012] Preferably, the undercoat layer of the barrier paper contains clay and latex, the mass ratio of the latex to the clay is from 0.3 to 1.0, and the aspect ratio of the clay is no greater than 30. When the undercoat layer of the barrier paper has the above-mentioned configuration, it is possible to further improve the flatness of the undercoat layer surface and the coatability when laminating a coating layer, and to enhance the effect of suppressing the impregnation of the coating liquid of the coating layer into the base paper.

[0013] The Beck smoothness of the surface of the base paper is preferably 20 seconds or more and 280 seconds or less. By having the Beck smoothness of the surface of the base paper, the filling property of the undercoat layer can be further improved.

[0014] An industrial material or packaging material according to one aspect of the present invention includes the barrier paper. By including the barrier paper, the industrial material or packaging material can have excellent gas barrier properties and water vapor barrier properties, and can be thin and multifunctional.

[0015] [Details of the embodiment of the present invention] The present invention will be described in detail below. The following description of the components may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments.

[0016] <Barrier paper> The barrier paper comprises a base paper, an undercoat layer laminated on one or both sides of the base paper, and a coating layer laminated on the surface of the undercoat layer.

[0017] [Base material] The substrate is obtained by papermaking a slurry containing raw pulp. The substrate may be either a single layer or a multilayer.

[0018] (Raw pulp) The base material is mainly composed of pulp. For example, virgin pulp, recycled paper pulp, or a combination of these pulps can be used as the raw pulp constituting the base material. The "main component" refers to the component with the highest content, that is, the component with a content of 50% by mass or more.

[0019] Examples of virgin pulp include chemical pulps such as bleached hardwood kraft pulp (LBKP), bleached softwood kraft pulp (NBKP), semi-bleached hardwood kraft pulp (LSBKP), semi-bleached softwood kraft pulp (NSBKP), hardwood sulfite pulp, and softwood sulfite pulp; and mechanical pulps (MP) such as stone ground pulp (SGP), pressurized stone ground pulp (TGP), chemi-ground pulp (CGP), groundwood pulp (GP), and thermomechanical pulp (TMP). These pulps may be produced chemically or mechanically, either alone or in combination. From the viewpoint of appearance of the printed surface and use in food packaging applications, it is preferable to use only bleached kraft pulp.

[0020] Examples of waste paper pulp that can be used include disintegrated waste paper pulp, disintegrated and deinked waste paper pulp (DIP), and disintegrated, deinked and bleached waste paper pulp, which are produced from, for example, brown waste paper, kraft envelope paper, magazine paper, newspaper paper, flyer paper, office paper, corrugated cardboard paper, white waste paper, Kent waste paper, imitation waste paper, and land certificate paper, and can be used alone or in combination.

[0021] (Other additives) Other additives may be added to the base material as necessary, such as fillers, pigments, sizing agents, coagulants, oil-resistant agents, fluorescent whitening agents, aluminum sulfate, retention aids, drainage aids, dry strength agents, wet strength agents, coloring dyes, coloring pigments, and water-resistant agents, which may be used alone or in combination.

[0022] (Basis weight of base paper) The basis weight is measured in accordance with JIS-P8124 (2011). The basis weight of the base paper is not particularly limited, but the lower limit of the basis weight is 15.0 g / m 2 is preferred, and 30.0 g / m 2 The upper limit of the basis weight of the base paper is 140.0 g / m 2 is preferred, and 120.0 g / m 2 When the basis weight of the base paper is within the above range, the processing suitability of the barrier paper can be improved.

[0023] (Base paper density) The density of the base paper is 0.60g / cm 3 More than 1.05g / cm 3 By having the density of the base paper in the above range, it is possible to achieve a low basis weight and a lighter weight while maintaining folding strength, so that the barrier paper has excellent processability.

[0024] (Base paper thickness) The thickness of the base paper is preferably 30 μm or more and 150 μm or less. By keeping the thickness of the base paper within the above range, it is possible to achieve low basis weight and light weight while maintaining strength.

[0025] (Beck smoothness of the base paper surface) The lower limit of the Beck smoothness of the surface of the base paper on which the undercoat layer is provided is 20 seconds, preferably 30 seconds. On the other hand, the upper limit of the Beck smoothness is 280 seconds, preferably 250 seconds. When the Beck smoothness of the surface of the base paper is equal to or higher than the lower limit, the sealing property of the coating liquid of the undercoat layer is improved, thereby improving the properties of the coating layer. On the other hand, when the Beck smoothness of the surface of the base paper exceeds the upper limit, pinholes may occur in the undercoat layer, and when a coating layer is formed on top of the pinholes, the properties of the coating layer may be deteriorated. The Beck smoothness is a value according to "Paper and cardboard - Smoothness test method using a Beck smoothness tester" described in JIS-P8119 (1998). The Beck smoothness is evaluated from the amount of air flow (air leak). The Beck smoothness is measured by sandwiching the sheet to be measured between a glass sample stage with an optically flat finish and a rubber presser at a pressure of 100 kPa, and 10 ml of air is spread over a relatively wide area of ​​10 cm. 2 It is expressed as the time required for the liquid to pass between the glass standard surface and the sample and flow into a vessel held at a reduced pressure of about 370 mml of mercury, and indicates the smoothness of the surface of the object being measured. Beck smoothness evaluates the macroscopic smoothness of a relatively large surface. In the case of the barrier paper, the waviness of the surface of the base paper can be evaluated by Beck smoothness. Therefore, the surface of the base paper can be more appropriately evaluated by Beck smoothness.

[0026] [Undercoat layer] The barrier paper comprises an undercoat layer laminated on one or both sides of the base paper. That is, the coating layer is laminated on the surface of the undercoat layer. By providing the undercoat layer, the barrier paper can improve the coatability and the flatness of the coating layer surface when laminating the coating layer, and also functions as a so-called filling layer that prevents the coating liquid of the coating layer from penetrating into the base paper and reduces the amount of coating liquid used. The undercoat layer contains clay and latex. Here, the base paper on which the undercoat layer is laminated is sometimes simply referred to as the undercoat layer.

[0027] (clay) Examples of the clay include fine clay, secondary clay, primary clay, engineered clay, etc. Among these, fine clay is preferred from the viewpoint of achieving a good balance between penetration and inhibition of the barrier layer coating liquid and adjusting the moisture permeability to a specific range.

[0028] The upper limit of the aspect ratio of the clay is preferably 30, more preferably 25, and particularly preferably 20. When the aspect ratio of the clay is 30 or less and the average particle size of the clay is within the above range, some distortion occurs in the clay arrangement on the surface of the undercoat layer, so that the coating liquid of the coating layer can moderately penetrate into the base paper, improving the coatability and improving the properties of the coating layer. In addition, the coating liquid of the coating layer can be uniformly applied and the penetration into the base paper can be suppressed, so that high barrier properties can be obtained with a low coating amount. On the other hand, the lower limit of the aspect ratio of the clay is preferably 12. When the aspect ratio of the clay is less than 12, a large distortion occurs in the clay arrangement on the surface of the undercoat layer, so that the coating liquid penetrates excessively into the base paper, and the coating layer becomes non-uniform, and there is a risk that the area where the effect is exerted is limited. Here, the aspect ratio refers to the ratio of the major axis (longest axis) to the thickness (shortest axis) of the shape of the inorganic particle. The aspect ratio can be obtained, for example, by particle image analysis using a laser diffraction / scattering particle distribution analyzer (Horiba LA 950, manufactured by Horiba, Ltd.) or by photographing powder particles with an electron microscope and dividing the diameter by the thickness of 500 randomly selected particles to obtain the average value.

[0029] The lower limit of the average particle diameter of the clay is preferably 2.0 μm or less, more preferably 1.0 μm or less. Meanwhile, the upper limit of the average particle diameter of the clay is preferably 0.3 μm or less, more preferably 0.4 μm or more. When the average particle diameter of the clay is within the above range, the unevenness of the surface of the undercoat layer is reduced, improving the coatability of the coating liquid for the coating layer and improving the properties of the coating layer. In addition, the coating liquid for the coating layer can be uniformly applied and penetration into the base paper is suppressed, so that high barrier properties can be achieved with a low coating amount. The above average particle diameter is the median diameter (D50 ).

[0030] The undercoat layer may contain other pigments besides clay. Examples of the other pigments include light calcium carbonate, heavy calcium carbonate, silica particles, magnesium carbonate, magnesium hydroxide, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, alumina, colloidal alumina, alumina hydrate (pseudoboehmite, etc.), aluminum hydroxide, lithopone, zeolite, hydrated halloysite, etc., which may be used alone or in combination of two or more. The content of the other pigments is preferably 10% by mass or less in terms of solid content relative to the undercoat layer.

[0031] (latex) The barrier paper contains latex as a binder. Any known latex used in forming a coating layer in coated paper can be used as the latex, but it is particularly preferable to use styrene-butadiene copolymer latex (SBR), which is inexpensive and provides an anchoring effect for the base paper.

[0032] The latex is not particularly limited, and various copolymer latexes such as styrene-butadiene copolymers, styrene-acrylic copolymers, ethylene-vinyl acetate copolymers, butadiene-methyl methacrylate copolymers, vinyl acetate-butyl acrylate copolymers, maleic anhydride copolymers, and acrylic acid-methyl methacrylate copolymers can be used, and one or more types can be used in combination. Among these, it is preferable to use a styrene-butadiene copolymer latex from the viewpoint of preventing fine particles from falling off.

[0033] The lower limit of the mass ratio of the latex to the clay (solid content equivalent) is preferably 0.3, more preferably 0.4. On the other hand, the upper limit of the mass ratio of the latex to the clay is preferably 1.0, more preferably 0.9. When the mass ratio of the latex to the clay is within the above range, the flatness of the undercoat layer surface and the coatability when laminating the coating layer can be further improved, and the effect of suppressing the impregnation of the coating liquid of the coating layer into the base paper can be enhanced. If the mass ratio of the latex to the clay is less than the above lower limit, the strength of the undercoat layer may not be sufficient. On the other hand, if the mass ratio of the latex to the clay exceeds the above upper limit, the fluidity of the coating liquid may be deteriorated, and the clay arrangement may be easily distorted.

[0034] In addition to the clay and binder, the undercoat layer may contain, as necessary, conventional additives such as clay dispersants, thickeners, flow improvers, antifoaming agents, foam inhibitors, lubricants, release agents, foaming agents, penetrating agents, UV absorbers, antioxidants, preservatives, antifungal agents, water-resistant agents, dyes, and fixing agents, as well as auxiliaries such as stearic acid, calcium stearate, oleic acid, calcium oleate, ammonium oleate, lecithin, polyethylene, wax, and derivatives thereof.

[0035] The lower limit of the coating weight of the undercoat layer (solid content equivalent) is 5.0 g / m 2 is preferred, and 5.5 g / m 2 On the other hand, the upper limit of the coating amount (converted into solid content) is preferably 15.0 g / m from the viewpoint of improving the sealing property. 2 is preferred, and 14.0 g / m 2 If the coating weight of the undercoat layer is less than the lower limit, the unevenness of the base paper surface cannot be sufficiently filled, and the coatability of the coating liquid for the coating layer is reduced, which may result in the coating layer not having good properties. On the other hand, if the coating weight is more than the upper limit, the flexibility of the undercoat layer is reduced, which may result in the processing suitability of the barrier paper being reduced.

[0036] (Beck smoothness of the undercoat layer surface) The lower limit of the Beck smoothness of the surface of the undercoat layer is 30 seconds, preferably 35 seconds. On the other hand, the upper limit of the Beck smoothness is 300 seconds, preferably 250 seconds. When the Beck smoothness of the surface of the undercoat layer is equal to or greater than the lower limit, the applicability of the coating liquid of the coating layer is improved, and the properties of the coating layer can be improved. In addition, the coating liquid of the coating layer can be uniformly applied, and the penetration into the base paper can be suppressed, so that a high barrier property can be obtained with a low coating amount. On the other hand, when the Beck smoothness of the surface of the undercoat layer exceeds the upper limit, the undercoat layer shows high flatness (improved slipperiness) even when the coating layer is formed, so that the suitability for bag making may be reduced. Furthermore, by preventing the Beck smoothness from becoming even higher by calendering or the like after the formation of the undercoat layer, the undercoat layer is less likely to have micro-defects such as pinholes.

[0037] In addition, it is preferable that the difference in Beck smoothness between the surface of the base paper and the surface of the undercoat layer is within 100 seconds. By keeping the difference in smoothness within 100 seconds, it is possible to achieve both coating layer properties and processability. If the difference in smoothness exceeds the above range, a calendaring process can be performed after the application of the undercoat layer, but this may cause cracks to easily occur in the undercoat layer, which may reduce the sealing ability.

[0038] (Density of base paper with undercoat layer laminated) The lower limit of the density of the base paper on which the undercoat layer is laminated is 0.70 g / cm 3 and 0.75 g / cm 3 On the other hand, the upper limit of the density of the base paper on which the undercoat layer is laminated is 1.10 g / cm. 3 and 1.05 g / m 2 When the density of the base paper on which the undercoat layer is laminated is within the above range, tearing and crease splitting that occur during processing such as bag making can be prevented.

[0039] (Thickness of base paper with undercoat layer laminated) The lower limit of the thickness of the base paper on which the undercoat layer is laminated is 40 μm, and preferably 50 μm. Meanwhile, the upper limit of the thickness of the base paper on which the undercoat layer is laminated is 100 μm, and preferably 85 μm. When the thickness of the base paper on which the undercoat layer is laminated is equal to or greater than the lower limit, the sealing properties of the undercoat layer can be improved and the processability of the barrier paper can be improved. When the thickness of the base paper on which the undercoat layer is laminated is equal to or less than the upper limit, the processability of the barrier paper can be improved.

[0040] (Moisture permeability of base paper with undercoat layer laminated) The lower limit of the moisture permeability of the base paper with the undercoat layer is 800 g / m 2 24hr, 900g / m 2 On the other hand, the upper limit of the moisture permeability of the base paper on which the undercoat layer is laminated is 2000 g / m 2 24h, 1800g / m 2 ·24 hours is preferable. When the moisture permeability of the base paper on which the undercoat layer is laminated is within the above range, the moisture of the undercoat layer is maintained at an appropriate level, improving the affinity between the components of the coating layer and the undercoat layer, and allowing the coating layer to be laminated uniformly.

[0041] [Coating layer] The coating layer is laminated on the surface of the undercoat layer. The coating layer contains a vinylidene chloride copolymer. Since the coating layer contains a vinylidene chloride copolymer, the barrier paper can have both gas barrier and water vapor barrier properties with a single coating layer. Furthermore, since the vinylidene chloride copolymer has a low heat sealing temperature, it also has heat sealing performance.

[0042] The lower limit of the content of the vinylidene chloride copolymer in the coating layer is 50 mass %, preferably 70 mass %, more preferably 90 mass %, and even more preferably 95 mass %, calculated as solid content. The content of the vinylidene chloride copolymer in the coating layer within the above range can further improve the gas barrier property and water vapor barrier property. Here, the content of the vinylidene chloride copolymer in the coating layer may be 100 mass %.

[0043] In the vinylidene chloride copolymer, specific examples of other monomers copolymerizable with vinylidene chloride include vinyl chloride, acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate, methacrylic acid esters such as methyl methacrylate and glycidyl methacrylate, acrylonitrile, methacrylonitrile, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, and maleic acid, and the like. In addition, two or more vinylidene chloride copolymers can be used in appropriate combination. Furthermore, additives such as heat stabilizers, light stabilizers, and lubricants can be added to the vinylidene chloride copolymers. The vinylidene chloride copolymers are usually used as emulsions or solutions.

[0044] In addition to the vinylidene chloride copolymer, the coating layer (coating liquid) may contain, as necessary, conventional additives such as thickeners, flow improvers, antifoaming agents, foam inhibitors, lubricants, release agents, foaming agents, penetrating agents, coloring dyes, coloring pigments, fluorescent brightening agents, ultraviolet absorbers, antioxidants, preservatives, antifungal agents, water-resistant agents, dyes, and fixing agents.

[0045] The lower limit of the coating amount (solid content equivalent) of the coating layer is 3.0 g / m 2 is preferred, and 3.5 g / m 2 On the other hand, the upper limit of the coating amount is preferably 15.0 g / m from the viewpoint of achieving both high oxygen barrier property and water vapor barrier property and further improving the heat sealability. 2 is preferred, and 14.0 g / m 2 If the coating weight of the coating layer is less than the lower limit, it may be difficult to provide both gas barrier property and water vapor barrier property, whereas if the coating weight exceeds the upper limit, the barrier paper may become hard and may not be suitable for bag making.

[0046] When an undercoat layer and a coating layer are laminated on both sides of the base paper, the components, coating amount, etc. of the undercoat layer and the coating layer may be as described above.

[0047] [Barrier paper physical properties] (Basis weight of barrier paper) The basis weight of the barrier paper is 23.0 g / m 2 More than 150.0g / m 2 The following is preferable. By having the basis weight of the barrier paper in the above range, it is possible to reduce the weight while maintaining strength.

[0048] (Barrier paper thickness) The lower limit of the thickness of the barrier paper is 40 μm, preferably 45 μm, and the upper limit of the thickness is 150 μm, preferably 100 μm. By keeping the thickness of the barrier paper within the above range, it is possible to achieve a low basis weight and a lighter weight while improving processability.

[0049] [Barrier paper manufacturing method] The method for producing the barrier paper is not particularly limited, and may include, for example, a step of making a base paper from a raw pulp slurry and subjecting it to a press part and a dryer part, a step of applying an undercoat layer coating liquid in an undercoater part, and then laminating the undercoat layer by drying and flattening treatment, and a step of applying a coating liquid for the coating layer onto the surface of the undercoat layer.

[0050] Examples of coating devices used when applying the coating liquid for the coating layer or the coating liquid for the undercoat layer include a size press, a blade metering size press, a rod metering size press, a blade coater, a bar coater, a gate roll coater, a rod coater, and an air knife coater.

[0051] As a calendering device for the calendering process, various calenders such as a super calender, a gross calender, a soft compact calender, etc., which are a combination of a metal or drum and an elastic roll, are appropriately used in an on-machine or off-machine specification.

[0052] [Industrial materials or packaging materials] The industrial material or packaging material includes the barrier paper. By including the barrier paper, it is possible to obtain a thin, multifunctional industrial material or packaging material that has excellent gas barrier properties and water vapor barrier properties.

[0053] Examples of such industrial materials include agricultural sheets, interleaving paper, sheets used in audio, clothing, building materials, etc., and sheets used in electrical and electronic equipment, and can be used to replace plastic materials. In addition, since the industrial materials can prevent the intrusion of oxygen and moisture, they can prevent the contents from spoiling and deteriorating, and also prevent the odor of the contents from escaping.

[0054] Examples of the packaging material include packaging materials for food, etc., paper barrier packaging materials used for packaging applications such as containers and cups, and applications as an alternative to plastic materials such as packs, pouches, boxes, shrink packaging, cans, laminate packaging, etc. The packaging material can suppress deterioration of the contents due to oxidation caused by oxygen and moisture, and can extend the storage period.

[0055] <Other embodiments> The present invention is not limited to the above-described embodiment, and can be embodied in various other forms in addition to the above-described forms with various modifications and improvements. EXAMPLES

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0057] [Examples 1 to 5 and Comparative Examples 1 to 9] (Base paper) A pulp slurry consisting of 90% hardwood kraft pulp with a freeness of 450 ml and 10% softwood kraft pulp with a freeness of 600 ml was mixed with 2.0 kg / t of a paper strength agent and 1.0 kg / t of a neutral rosin-based internal sizing agent to prepare a base paper.

[0058] (Undercoat layer) Next, a coating solution having the composition shown in Table 2 was applied to both sides of this base paper to form an undercoat layer. The materials of the coating solution for the undercoat layer are as follows. (1) Fine clay (Shiraishi Calcium Co., Ltd., product name: Kaofine) (2) Styrene-butadiene copolymer (SB) latex (manufactured by Asahi Kasei Corporation, product name: A7090) (3) Light calcium carbonate (Shiraishi Kogyo Co., Ltd. "Brilliant 15") (4) Heavy calcium carbonate (Fimatec "FMT-90") (5) Engineered clay (Imerys "Varisurf HX") (6) Polyvinyl alcohol (Kuraray Co., Ltd. "11-98") (7) Styrene-acrylic copolymer ("Saibinol EK-81" manufactured by Saiden Chemical Co., Ltd.) (8) Wax resin ("Ripax A-240" manufactured by Toho Chemical Industry Co., Ltd.)

[0059] (Coating layer) Except for Comparative Example 7, a coating solution for a coating layer having a composition shown in Table 3 was applied onto the surface of the undercoat layer to form a coating layer. The materials for the coating solution of the coating layer are as follows: Polyvinylidene chloride (Manufacturer: Asahi Kasei, Product name: Saran Latex L536B)

[0060] The amounts of the additives described above were expressed as the amount converted into the solid content relative to the bone dry pulp amount. The undercoat layer and the coating layer were applied only to one side of the base paper, and the coating amounts were as shown in Tables 2 and 3.

[0061] [Table 1]

[0062] [Table 2]

[0063] [Table 3]

[0064] [evaluation] The obtained barrier paper was evaluated by the following methods.

[0065] <Basic weight> Basis weight (g / m 2 ) was measured in accordance with JIS-P-8124 (2011) "Paper and paperboard -- Determination of basis weight."

[0066] <Thickness> The thickness was measured in accordance with JIS-P8118 (2014).

[0067] <density> The density was measured in accordance with "Paper and paperboard - Test methods for thickness and density" described in JIS-P8118 (2014).

[0068] <Beck smoothness> The Beck smoothness was measured in accordance with "Paper and paperboard - Smoothness test method using a Beck smoothness tester" described in JIS-P8119 (1998).

[0069] <Sealing ability of undercoat layer> The sealing ability of the undercoat layer was evaluated by dropping toluene colored with oil-based ink onto the surface of the undercoat layer, wiping it off immediately with a cloth, and visually checking for breakthrough to the back side. The evaluation of little breakthrough to the back side indicates good sealing ability of the undercoat layer. Good results in the above sealing ability indicate good coating layer properties, and uniform results can be obtained without fluctuation in oxygen permeability and moisture permeability. The evaluation criteria were as follows: A: There is no bleed-through to the back side. B: 1 spot of 0.5mm or more bleed through to the back side / m 2 2 or more locations / m 2 The following exists. C: 3 spots / m with 0.5mm or more penetration to the back side 2 More than 10 locations / m 2 The following exists. D: 10 spots / m with 0.5mm or more of penetration to the back side 2 exists super-

[0070] <Moisture permeability> Measurements were performed under condition B in accordance with JIS-Z0208

[1976] Moisture permeability test method for moisture-proof packaging materials [cup method].

[0071] <Oxygen permeability> The measurement was carried out according to the following procedure. In accordance with JIS-K-7126-1:2006 "Plastics - Films and sheets - Gas permeability test methods - Part 1: Differential pressure method", the oxygen permeability of the barrier paper was measured in an atmosphere of 23°C using GTR Tech's "GTR-11AET".

[0072] <Evaluation of coating layer properties> The properties of the coating layer were evaluated by the following procedures. The properties of the coating layer of the barrier paper obtained in the Examples and Comparative Examples were judged visually. If there are any uneven areas in the coating layer, the oxygen permeability and moisture permeability will be poor in those areas, making it unusable as barrier paper. The properties of the coating layer were judged according to the following criteria. A and B are acceptable. (Evaluation Criteria) A: The coating layer is uniform and good, and the adhesion is good. B: The coating layer is partially uneven, or the adhesion of the coating layer does not cause any problems in use. C: The coating layer has noticeable uneven areas, or the coating layer has poor adhesion and is therefore problematic in use. D: The coating layer is uneven or the adhesion of the coating layer is weak and cannot be used.

[0073] <Heat sealability> The heat sealability was evaluated according to the following procedure. Using a thermal gradient tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the sealer pressure was 2kgf / cm 2After processing under conditions of a sealer time of 2 seconds and a sealing temperature of 140°C, the peel strength of the heat-sealed portion was measured using a load cell type tensile tester. The heat sealability of the barrier papers obtained in the Examples and Comparative Examples was judged according to the following criteria. A and B are acceptable. (Evaluation Criteria) A: The peel strength is 2.5N / mm or more. B: The peel strength is 2.0 or more and less than 2.5 N / mm. C: Peel strength is 1.5 or more and less than 2.0 N / mm. D: The peel strength is less than 1.5 N / mm.

[0074] <Processing suitability> The processability of the barrier paper was evaluated using the following procedure. The barrier paper was processed into individual bags by heat sealing, and the creases during bag making were evaluated. The processing suitability of the barrier paper obtained in the examples and comparative examples was judged according to the following criteria. A and B are acceptable. (Evaluation Criteria) A: There are no wrinkles or tears at the folds of the bottom and edges of the individual packages and the appearance is good. B: There are wrinkles on the folds at the bottom and edges of the individual packaging, but they are not significant enough to affect use. C: There are slight wrinkles and tears at the folds at the bottom and ends of the individual packaging, which is at a level that makes it problematic to use. D: The bottom and end folds of the individual packaging are wrinkled and torn and cannot be used.

[0075] The above measurement results and evaluation results are shown in Tables 1 to 3.

[0076] As shown in Table 3, the thickness of the barrier paper is 40 μm or more and 100 μm or less, the Beck smoothness of the surface of the undercoat layer is 30 seconds or more and 300 seconds or less, and the density of the base paper on which the undercoat layer is laminated is 0.70 g / cm 3 More than 1.10g / cm 3 The thickness of the undercoat layer is 40 μm or more and 100 μm or less, and the moisture permeability is 800 g / m 2 ·2000g / m over 24hr 2The barrier papers of Examples 1 to 8, which had a shelf life of 100% or less and a vinylidene chloride copolymer content in the coating layer of 50% or more by mass calculated as solids, had excellent gas barrier properties, water vapor barrier properties, coating layer properties, and processability. Furthermore, the barrier papers of Examples 1 to 5 also had good heat sealability.

[0077] On the other hand, in Comparative Examples 1 to 7 and 9, which did not meet the above requirements, the barrier paper was evaluated as not satisfying at least one of the oxygen permeability, moisture permeability, coating layer properties, heat sealability and processability. As for Comparative Example 8, in which a wax resin was added to the coating solution for the coating layer, the affinity between the coating solution and the base paper surface was poor, and a coating layer could not be formed, so it was not evaluated. In addition, in Comparative Example 4, the aspect ratio of the engineered clay contained in the undercoat layer was high, so that the moisture permeability of the base paper on which the undercoat layer was laminated was too low, and the properties of the coating layer (adhesion between the coating layer and the base paper on which the undercoat layer was laminated) were poor. In Comparative Example 5, the density and thickness of the base paper on which the undercoat layer was laminated exceeded the above upper limits, so that the thickness of the barrier paper was large and the processing suitability was poor. In Comparative Examples 2 and 3, in which the moisture permeability of the base paper on which the undercoat layer was laminated greatly exceeded the upper limit, the properties of the coating layer were poor. Furthermore, in Comparative Example 6, in which the undercoat layer did not contain clay and latex, the moisture permeability of the base paper on which the undercoat layer was laminated was very high, and in Comparative Example 7, which did not have a coating layer, no barrier performance was obtained. In Comparative Example 9, in which the thickness of the undercoat layer was 40 μm or less, the undercoat layer was thin and the pinholes in the base paper affected the sealing effect. As a result, the function as a barrier paper was reduced. In addition, the processing suitability was also poor. In Comparative Example 10, where the density of the base paper on which the undercoat layer was laminated exceeded the upper limit after the undercoat layer was formed and calendered, pinholes were generated in the undercoat layer, and the sealing property was reduced. In addition, the cushioning property was slightly reduced, and therefore the function as a barrier paper was also reduced.

[0078] The above results show that the barrier paper is thin and has excellent gas barrier and water vapor barrier properties, as well as heat sealability. Therefore, the barrier paper is suitable as a thin, multifunctional industrial material or packaging material.

Claims

1. A base paper and An undercoat layer laminated on one or both sides of the base paper; a coating layer laminated on the surface of the undercoat layer; Equipped with The density of the base paper on which the undercoat layer is laminated is 0.70 g / cm ３ 1.10g / cm or more ３ is as follows: The thickness of the base paper on which the undercoat layer is laminated is 40 μm or more and 100 μm or less, The moisture permeability of the base paper on which the undercoat layer is laminated is 800 g / m ２ ・2000g / m for 24hr or more ２ - 24 hours or less, The Beck smoothness of the surface of the undercoat layer is 30 seconds or more and 300 seconds or less, The coating layer contains a vinylidene chloride copolymer, The barrier paper, wherein the content of the vinylidene chloride copolymer in the coating layer is 50% by mass or more, calculated as a solid content.

2. The coating weight of the coating layer is 3.0 g / m ２ 15.0g / m or more ２ 2. The barrier paper of claim 1, wherein:

3. the undercoat layer contains clay and latex; a mass ratio of the latex to the clay is equal to or greater than 0.3 and equal to or less than 1.0; 3. The barrier paper according to claim 1 or 2, wherein the clay has an aspect ratio of 30 or less.

4. 4. The barrier paper according to claim 1, 2 or 3, wherein the Beck smoothness of the surface of the base paper is from 20 seconds to 280 seconds.

5. 5. An industrial or packaging material comprising a barrier paper according to any one of claims 1 to 4.

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