Oil-resistant paper and heat-sealable oil-resistant paper

Abstract

The present invention addresses the problem of providing an oil-resistant paper in which a non-fluorine-based oil-resistant agent is used.　As a solution, a paper base material is impregnated with an oil-resistant paint containing a non-fluorine-based oil-resistant agent and a water-soluble polymer. The paper base material has a basis weight of 20 g / m2 or greater. The paper base material contains, as raw material pulp, 30 wt% or more of hardwood pulp for which the ratio (l / D) of the lumen width (l) to the fiber width (D) is 0.50 or less on average. The Shopper-Riegler freeness of the pulp constituting the paper base material is 25-45°SR.

Description

Technical Field

[0001] The present invention relates to heat-sealable oil-resistant paper having an oil-resistant paper and a heat-sealing layer.

Background Art

[0002] Oil-resistant paper is paper having a function of preventing the penetration of oil. Oil-resistant paper is widely used, for example, as a packaging material for wrapping fried foods such as tempura and fries, or as a bag for packing hamburgers, French fries, fried chicken, etc. in fast food restaurants and convenience stores. Conventionally, oil-resistant paper has been mainly a paper base material coated with a fluororesin-based oil-resistant agent such as perfluorohydrocarbon acrylate or perfluorohydrocarbon phosphate ester. However, it has been confirmed that fluorine-based oil-resistant paper coated with a fluororesin-based oil-resistant agent generates perfluoroalcohol with high environmental accumulation when heated to 100 to 180°C. In addition, when oil-resistant paper using these fluororesin-based oil-resistant agents is incinerated after use, fluorine compounds such as perfluorooctanoic acid and perfluorosulfonic acid are generated, and there are concerns about adverse effects on the health of animals including humans and the environment. In addition, since other low-molecular fluorine compounds are generally hardly decomposable, oil-resistant paper that does not use fluorine-based compounds is particularly desired for food packaging applications.

[0003] Oil-resistant paper for food packaging is required to have oil barrier properties such that oil does not leak through the paper to the opposite side, and oil penetration prevention properties such that the attached oil does not easily spread on the surface of the oil-resistant paper and does not exhibit an appearance in which the oil soaks in (the soaked part discolors). Furthermore, oil-resistant paper for food packaging is required to have properties such that the contents are difficult to see from the outside when packaging food, contain no harmful substances, and have dissociability (recyclability) and can be reused as resources.

[0004] Patent Document 1 proposes an oil-resistant paper obtained by applying a water-soluble polymer to a base material made of natural fibers for papermaking containing a filler. Patent Document 1 aims to achieve recyclability without using fluorine-based compounds. By providing a water-soluble polymer layer as an oil-resistant layer on a base material with a high air permeability resistance obtained by highly beating natural fibers for papermaking to a freeness of 85 to 90 °SR, it provides the desired oil-resistant paper. Patent Document 2 proposes an oil-resistant paper obtained by applying an oil-resistant layer composed of a non-fluorine-based oil-resistant agent and polyethylene wax with an average particle size of 1 to 20 μm to a paper base material. Patent Document 2 presents acrylic resin, starch, and polyvinyl alcohol as non-fluorine-based oil-resistant agents, and by setting the smoothness and air permeability of the paper base material within a specified range, it provides an oil-resistant paper that addresses the operational and cost issues related to the application of these oil-resistant agents. Patent Document 3 proposes an oil-resistant paper that does not use a fluorine-based compound. The raw material of the paper base material is hardwood pulp / softwood pulp (L / N ratio): 0 / 100 to 70 / 30 (mass ratio), the beating degree is 45 °SR or more, and the density of the as-made base paper is 0.45 g / cm 3 Above 0.75 g / cm 3 Hereinafter, with the Stein size degree being 5 seconds or more, an oil-resistant paper obtained by applying a styrene-acrylic copolymer resin and paraffin wax to this paper base material at a blending ratio of 90:10 to 10:90 (mass ratio) has been proposed. Patent Document 3 explains that the styrene-acrylic copolymer resin gives film-forming properties to the oil-resistant layer, and the paraffin wax plays a role in improving the oil-resistant performance by existing in the voids of the paper base material.

[0005] Patent Documents 4 and 5 propose oil-resistant papers using one or more of modified starch, amylose, and polyvinyl alcohol as oil-resistant agents. The paper base material mainly consists of pulp fibers. For the application of the oil-resistant layer, Patent Document 4 adopts an impregnation method, and Patent Document 5 adopts a method of spray coating between the layers of multi-layer paper. Although neither document specifies the basis weight of the paper base material, the examples are carried out in a basis weight range of 200 to 300 g / m 2 Above. Patent Document 6 discloses that a paper base material contains a polylactic acid-based resin, a polyvinyl alcohol-based resin, and / or a starch-based compound in a ratio of 70:30 to 98:2 (dry weight ratio) at 3 g / m2 20 g / m or less 2 There has been proposed an oil-resistant paper coated at 20 g / m or less. Patent Document 6 provides an oil-resistant paper that has heat-sealing properties, prevents the generation of harmful substances during combustion, and is degradable when it leaks into the environment by incorporating a biodegradable resin without using a fluorine-based compound in the oil-resistant layer.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide an oil-resistant paper using a non-fluorine-based oil-resistant agent. Another object of the present invention is to provide an oil-resistant paper having uniform quality with little variation in oil resistance performance on a paper base material with a wide basis weight.

Means for Solving the Problems

[0008] Means for solving the problems of the present invention are as follows. 1. The paper base material is impregnated with an oil-resistant paint containing a non-fluorine-based oil-resistant agent and a water-soluble polymer, wherein the paper base material has a basis weight of 20 g / m 2As described above, an oil-resistant paper containing 30% by weight or more of hardwood pulp having an average ratio (l / D) of lumen width (l) to fiber width (D) of 0.50 or less as raw material pulp, and having a Schopper-Riegler drainage degree of the pulp constituting the paper base material of 25°SR or more and 45°SR or less. 2. The adhesion amount of the oil-resistant paint is 1.3 g / m in terms of dry weight. 2 and above. The oil-resistant paper according to 1, wherein the kit value measured by J.TAPPI No.41:2000 of the impregnated surface is 2 or more. 3. The oil-resistant paper according to 1 or 2, wherein an oil resistance test is performed by an irregular kit method, and the opacity change rate before and after oil contact is 10% or less. (Irregular kit method) Using rapeseed oil (primary reagent) as the test liquid, dropping the test liquid onto a sample conditioned at 23°C and 50% RH for 10 hours, leaving it standing at 23°C and 50% RH for 3 hours, and then wiping off the rapeseed oil on the surface. Based on the opacity before oil contact, the opacity change rate is calculated according to the following formula. Opacity change rate = {(O B - O A ) / O B} × 100 O B : Opacity before oil contact O A : Opacity after oil contact 4. The oil-resistant paper according to any one of 1 to 3, having a disintegration drainage degree of 250 ml CSF or more and 500 ml CSF or less. 5. The oil-resistant paper according to any one of 1 to 4, wherein the water-soluble polymer contained in the oil-resistant paint is one or more selected from starch-based, acrylic resin, and polyvinyl alcohol-based resins. 6. The oil-resistant paper according to any one of 1 to 5, having a tensile strength of 1.5 kN / m or more. 7. A heat-sealable oil-resistant paper having a heat-sealing layer on at least one side of the oil-resistant paper according to any one of 1 to 6.

Effect of the Invention

[0009] Since the oil-resistant paper of the present invention does not use a fluororesin-based oil-resistant agent, it can suppress adverse effects on health and the environment. The oil-resistant paper of the present invention is suitable for a non-fluorine-based oil-resistant agent as the paper base material used, and by applying an oil-resistant layer containing a non-fluorine-based oil-resistant agent such as a synthetic polymer substance or a natural polymer substance that has been proposed as an alternative to the fluororesin-based oil-resistant agent, it can exhibit uniform oil resistance on the surface of the oil-resistant paper and efficiently exhibit the oil resistance performance of various non-fluorine-based oil-resistant agents.

Mode for Carrying Out the Invention

[0010] "Oil-resistant paper" The oil-resistant paper of the present invention is impregnated with an oil-resistant paint containing a non-fluorine-based oil-resistant agent and a water-soluble polymer on the paper base material. Whether the paint is impregnated or not can be determined by observing the cross section with a microscope or the like. ·Paper base material The paper base material used in the present invention contains 30% by weight or more of hardwood pulp having an average ratio (l / D) of lumen width (l) to fiber width (D) of 0.50 or less. Hereinafter, in this specification, the ratio (l / D) of lumen width (l) to fiber width (D) will also be simply referred to as "l / D".

[0011] Hardwood pulp fibers have a lumen called an inner cavity inside. l / D is a value indicating the ratio of the lumen width to the thickness of the fiber, and the smaller the value, the smaller the lumen and the thicker the fiber wall. The l / D of the pulp can be measured by the following procedure. 1. Dilute the pulp suspension to a concentration of 0.05%. 2. Using a dropping tube, drop the diluted solution onto a clean slide glass, and if necessary, use a dissecting needle to uniformly disperse the fibers and dry them. 3. Drop 3 drops of C staining solution onto the fibers dispersed on the slide glass, place a cover glass so that no air bubbles enter, remove the excess staining solution with blotting paper, and prepare a specimen. 4. Observe the prepared sample using an optical microscope, move the prepared sample horizontally or vertically on the movable stage, measure the fiber width (D) and lumen width (l) at the central part in the length direction of the pulp, and calculate l / D. When preparing the furnish, for the pulp to be blended, the l / D of 100 or more pulps can be determined by the above method, and the average value can be taken as the l / D of the pulp. From the paper made, the paper is disintegrated in the same manner as the slurry preparation for measuring the drainage degree of the paper, and for 200 or more pulps, it is discriminated using a staining solution that shows different colors depending on the tree species, etc., and by determining l / D by the above method, the blending amount of hardwood pulp and the l / D of the pulp can be determined.

[0012] (Hardwood pulp with l / D of 0.50 or less) Hardwood pulp with l / D of 0.50 or less forms a low-density sheet with a thick fiber wall that is difficult to crush. Although there are differences depending on the tree species and other blended pulps, by using a furnish containing 30% by weight or more of hardwood pulp with an average ratio (l / D) of lumen width (l) to fiber width (D) of 0.50 or less as the raw material pulp, even after performing the beating treatment necessary to obtain the paper strength required in the manufacturing process, a low-density, that is, a highly breathable paper base material can be obtained. Since the high air permeability of the paper base material enables the oil-resistant paint to be quickly impregnated into the entire paper base material and uniformly adhered, the unevenness in the oil resistance performance of the resulting oil-resistant paper can be reduced. The l / D of the hardwood pulp with l / D of 0.50 or less is preferably 0.45 or less, and more preferably 0.40 or less.

[0013] The hardwood pulp with l / D of 0.50 or less is not particularly limited, and examples include mechanical pulp (MP), thermomechanical pulp (TMP), sulfite pulp (SP), kraft pulp (KP), and their bleached pulp (BP), unbleached pulp (UP), etc., and one or more of these can be used in combination. Among these, it is preferable to use kraft pulp (KP) which is excellent in strength.

[0014] (Other pulp) As other pulp to be combined with hardwood pulp having an l / D of 0.50 or less, hardwood pulp having an l / D exceeding 0.50, softwood pulp, regenerated cellulose, refined pulp such as mercerized pulp and dissolving pulp, bast fibers such as flax, kenaf, kozo, and mitsumata, hard fibers such as bagasse, bamboo, and esparto, seed hair fibers such as cotton linter, and non-wood pulp such as leaf vein fibers of Manila hemp and sisal hemp can be used without particular limitation. Note that the pulp constituting the paper base material may be beaten after mixing hardwood pulp and other pulp, or may be used after separately beating hardwood pulp and other pulp and then mixing them. In the paper base material of the present invention, the hardwood pulp having an l / D of 0.50 or less is 30% by weight or more, preferably 40% by weight or more, more preferably 50% by weight or more, and even more preferably 60% by weight or more based on the total pulp as the papermaking raw material.

[0015] The paper base material of the present invention has a Schopper-Riegler drainage degree of 25°SR or more and 45°SR or less for the pulp constituting the paper base material. Note that the pulp constituting the paper base material means all the pulp contained in the paper base material. For a paper base material having a Schopper-Riegler drainage degree less than 25°SR, since the strength of the paper base material is low, when impregnating with an oil-resistant paint, breakage of the paper base material and deterioration of the texture of the paper base material are significantly manifested, and unevenness in oil resistance performance may occur. Also, when the Schopper-Riegler drainage degree exceeds 45°SR, uneven liquid absorption occurs in the paper base material when impregnating with an oil-resistant paint, and unevenness in the oil resistance performance of the oil-resistant paper may occur. This Schopper-Riegler drainage degree is preferably 27°SR or more and 40°SR or less, and more preferably 27°SR or more and 35°SR or less.

[0016] (Other additives) Other additives can be internally added to the paper base material as necessary. As additives, for example, fillers, pigments, sizing agents, coagulants, fluorescent brightening agents, sulfuric acid bands, yield improvers, drainage improvers, dry paper strength enhancers, wet paper strength enhancers, coloring dyes, coloring pigments, water resistance agents, etc. can be used alone or in combination of a plurality.

[0017] (Manufacturing method) The papermaking method of the paper base material can be manufactured using methods used in known papermaking applications. Specifically, it can be manufactured using a fourdrinier paper machine, a cylinder paper machine, a twin-wire paper machine, an on-top hybrid paper machine, a gap former machine, etc.

[0018] The basis weight of the paper base material is 20 g / m 2 or more. When the basis weight is less than 20 g / m 2 , the tensile strength becomes weak, and the paper base material may break during papermaking and oil-resistant layer processing. Also, the lower the basis weight of the base material, the more likely it is that uneven adhesion of the oil-resistant agent, which is considered to be affected by the state of the pulp fibers, will occur, and this causes uneven oil-resistant performance. The basis weight of the paper base material is not particularly limited as long as it is 20 g / m 2 or more, but for example, it can be 30 g / m 2 or more and 400 g / m 2 or less.

[0019] From the viewpoint of the permeability of the oil-resistant agent, the King Research air permeability of the paper base material is preferably 100 seconds or less. The King Research air permeability of the paper base material is more preferably 50 seconds or less, further preferably 30 seconds or less, and even more preferably 20 seconds or less. The King Research air permeability of the paper base material is preferably 2 seconds or more.

[0020] ·Oil-resistant paint The oil-resistant paint used in the present invention contains a non-fluorine-based oil-resistant agent and a water-soluble polymer and does not contain a fluorine-based oil-resistant agent. Also, the non-fluorine-based oil-resistant agent-containing paint preferably does not contain a low-molecular fluorine compound, and more preferably does not contain a fluorine-based compound.

[0021] (Non-fluorine-based oil-resistant agent) As the non-fluorine-based oil-resistant agent, it can be used without particular limitation. For example, among natural polymers, there are starch, cellulose derivatives, gelatin, casein, soy protein, etc. Among synthetic polymers, there are polymers or copolymers of polyvinyl alcohol, polyisoprene, chloroprene, polydiene, polyalkene, vinyl-based monomers, synthetic rubber latex, polyurethane-based resins, polyester-based resins, polyamide-based resins, olefin-maleic anhydride-based resins, silicone-based resins, acrylic-based resins, melamine-based resins, fatty acid ester-based resins, plant-based waxes, animal-based waxes, mineral-based waxes, petroleum-based waxes and other compounds. These can be used alone or in combination of two or more. Among these, from the viewpoint of oil resistance, acrylic-based resins and fatty acid ester-based resins are preferred, and from the viewpoint of preventing oil penetration, acrylic-based resins are more preferred.

[0022] (Water-soluble polymer) The water-soluble polymer acts as a hydrophilic binder that fixes the non-fluorine-based oil-resistant agent to the pulp fibers of the paper substrate without inhibiting the performance of the oil-resistant agent. Examples of the water-soluble polymer include anionic polymer electrolytes such as carboxyalkyl cellulose salts, alginates, pectates, polyacrylates, polymethacrylates, carboxyalkylated starches, phosphate esterified starches, anion-modified polyvinyl alcohol-based resins, anionic polyacrylamides, etc., and polymer non-electrolytes such as methyl cellulose, hydroxyalkyl cellulose, polyvinyl alcohol-based resins, polyvinylpyrrolidone, polyalkylene oxides, polyvinyl alkyl ethers, hydroxyalkylated starches, oxidized starches, alpha starches, etc., water-soluble polysaccharides such as guar gum, tragacanth gum, xanthan gum, gum arabic, carrageenan, galactomannan, pullulan, dextran, dextrin, etc., and water-soluble proteins such as gelatin and casein. These can be used alone or in combination of two or more. Among these, from the viewpoints of processability, oil resistance, and material price, starch-based (carboxyalkylated starch, phosphate esterified starch, hydroxyalkylated starch, oxidized starch, alpha starch), acrylic resin, and polyvinyl alcohol-based resin are preferable, and acrylic resin with excellent oil resistance is more preferable. Also, the water-soluble polymer preferably has a neutral charge or the same charge as the non-fluorine-based oil-resistant agent. However, those that do not form a uniform aqueous phase (e.g., phase separation, aggregation, etc.) when made into an aqueous solution of 10% by weight of the non-fluorine-based oil-resistant agent and 10% by weight of the water-soluble polymer cannot be used.

[0023] From the viewpoint of material cost, the oil-resistant paint preferably contains 5 to 100 parts by weight of the non-fluorine-based oil-resistant agent per 100 parts by weight of the water-soluble polymer, more preferably 10 parts by weight or more, even more preferably 15 parts by weight or more, and more preferably 70 parts by weight or less, even more preferably 50 parts by weight or less. In addition to the non-fluorine-based oil-resistant agent and the water-soluble polymer, the oil-resistant paint can also contain additives such as surfactants, defoamers, surface sizing agents, paper strength agents, water retention agents, thickeners, release agents, anti-slip agents, etc. within a range that does not impair its performance.

[0024] The oil-resistant paper of the present invention preferably has an oil resistance of 2 or more in terms of the kit value defined in J TAPPI No. 41:2000 on the impregnated surface. When the oil resistance is less than the kit value of 2, the oil from the food stored inside may seep out to the outside, and the outer surface may be soiled by the oil. This kit value may be 3 or more, 4 or more, 5 or more. Here, the kit value is represented by a number from 1 to 12, and a higher numerical value means better oil resistance (oil barrier property). Even if the kit value of the oil-resistant paper of the present invention is low, it has excellent oil penetration prevention property, and oil is difficult to penetrate and discolor. The upper limit of the kit value of the oil-resistant paper of the present invention can be, for example, 7 or less, 6 or less, 5 or less. From the viewpoint of preventing paper breakage during papermaking, etc., the tensile strength measured in accordance with JIS P8113:2006 of the oil-resistant paper of the present invention is preferably 1.5 kN / m or more, more preferably 1.7 kN / m or more, and even more preferably 2.0 kN / m or more.

[0025] (Impregnation method) The impregnation method of the oil-resistant paint is not particularly limited, and known impregnation methods and coating methods can be adopted. Specifically, it can be appropriately selected and used from impregnation coating by mangle, size press, etc., and surface coating by gate roll coater, blade coater, bar coater, champlex coater, gravure coater, die coater, curtain coater, air knife coater, spray coater, etc. Among these, the size press is preferable because of its excellent impregnation property of the paint. The oil-resistant paint may be either an aqueous system using a solvent such as water or a solvent system using a solvent such as an organic solvent, but from the viewpoint of safety and hygiene, an aqueous system is preferable.

[0026] To obtain an oil-resistant paper with a kit value of 2 or more, the adhesion amount of the oil-resistant paint is preferably 1.3 g / m 2 or more in terms of dry weight, more preferably 1.4 g / m 2 or more, and even more preferably 1.5 g / m 2 or more. The upper limit of the adhesion amount of the oil-resistant paint is not particularly limited, but for example, it is preferably 10 g / m 2 or less in terms of dry weight. When the adhesion amount of the oil-resistant paint is 10 g / m in terms of dry weight2 Even if it exceeds this, the oil resistance hardly improves any further, and it also results in high costs. The adhesion amount of the non-fluorine-based oil-resistant agent varies depending on the ratio of the non-fluorine-based oil-resistant agent in the oil-resistant paint. However, the adhesion amount of the non-fluorine-based oil-resistant agent is preferably 0.2 g / m 2 or more in terms of dry weight, more preferably 0.25 g / m 2 or more, and even more preferably 0.3 g / m 2 or more. The upper limit of the adhesion amount of the non-fluorine-based oil-resistant agent is not particularly limited. For example, it is preferably 5 g / m 2 or less in terms of dry weight. Even if the adhesion amount of the oil-resistant paint exceeds 5 g / m 2 in terms of dry weight, the oil resistance hardly improves any further, and it also results in high costs.

[0027] The oil-resistant paper of the present invention preferably has a change rate of opacity of 10% or less before and after oil contact when subjected to an oil resistance test by the following irregular kit method. When oil penetrates into the oil-resistant paper, the opacity decreases (becomes transparent) because the light scattering decreases. Therefore, the smaller the value of the change rate of opacity, the better the oil penetration prevention performance. For the oil-resistant paper of the present invention, the change rate of opacity is more preferably 9% or less, even more preferably 8% or less, still more preferably 7% or less, even more preferably 6% or less, even more preferably 5% or less, and even more preferably 4% or less. (Irregular kit method) Using rapeseed oil (primary reagent) as the test liquid, dropping the test liquid onto the one conditioned for 10 hours in an environment of 23°C and 50% RH, leaving it for 3 hours in an environment of 23°C and 50% RH, and then wiping off the rapeseed oil on the surface. Based on the following formula, the change rate of opacity is calculated from the opacity before oil contact. Change rate of opacity = {(O B - O A ) / O B} × 100 O B : Opacity before oil contact O A : Opacity after oil contact

[0028] The oil-resistant paper of the present invention preferably has a disintegration drainage degree of 250 ml CSF or more and 500 ml CSF or less. The disintegration drainage degree is the Canadian standard drainage degree measured in accordance with JIS P8121-2:2012 after disintegrating the oil-resistant paper by the method specified in JIS P8220-1:2012. The disintegration drainage degree is preferably 300 ml CSF or more and 450 ml CSF or less, and more preferably 350 ml CSF or more and 450 ml CSF or less.

[0029] "Heat-sealable oil-resistant paper" The heat-sealable oil-resistant paper of the present invention has a heat-sealing layer on at least one side of the oil-resistant paper described above in the present invention. The heat-sealing layer can be provided on both sides, but when provided on only one side, it is preferably provided on the processed surface impregnated with the oil-resistant paint. When applying the heat-sealing agent to the oil-resistant paper, due to the relationship of the wettability of the heat-sealing agent with respect to the oil-resistant paper, it may not be possible to uniformly apply the heat-sealing layer in the case of oil-resistant paper with a high Kit value. Therefore, when manufacturing the heat-sealable oil-resistant paper, when the heat-sealing layer cannot be uniformly applied, it is necessary to adjust the viscosity and solvent composition of the heat-sealing agent coating liquid.

[0030] (Heat-sealing layer) The heat-sealing layer is formed by coating at least one side of the greaseproof paper with a paint containing a thermoplastic resin having heat-sealing properties. As the thermoplastic resin contained in the heat-sealing layer, known ones can be used without particular limitation, and examples thereof include polyethylene-based resins and polypropylene-based resins. Examples of the polyethylene-based resin include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-vinyl acetate copolymer (EVA), carboxylic acid-modified polyethylene, ionomer, and derivatives thereof, and mixtures thereof. Examples of the polypropylene-based resin include polypropylene (PP) homopolymer, random polypropylene (random PP), block polypropylene (block PP), chlorinated polypropylene, carboxylic acid-modified polypropylene, and derivatives thereof, and mixtures thereof. Among these, those having a glass transition temperature of 100°C or lower can be preferably used. The thermoplastic resin preferably has a glass transition temperature of -20°C or higher and 85°C or lower, and a melting point of 70°C or higher and 140°C or lower. The glass transition temperature and the melting point respectively mean the midpoint glass transition temperature and the melting peak temperature measured in accordance with JIS P7121:2012.

[0031] In addition to the thermoplastic resin, the heat-sealing layer can also contain a surfactant, wax, inorganic pigment, dispersant, thickener, etc. as required. The heat-sealing layer preferably has a heat-sealing strength of 2.3 N / 15 mm or more, more preferably 2.9 N / 15 mm or more, as measured by the following method. (Measurement conditions) The heat-sealing surfaces of the heat-sealing greaseproof papers were brought into contact with each other, and heat-sealing was performed at a pressure temperature of 160°C, a pressure of 98 kPa, and a pressure time of 1 second using a heat-sealing tester (manufactured by Tester Sangyo Co., Ltd., TP-7018). After heat sealing, the sample was left at 23°C and 50% RH for 10 minutes. Under this atmosphere, using a tensilon universal testing machine RTG-1210 (A&D Company, Limited), the sealed part of the measurement sample was peeled at a tensile speed of 300 mm / min, and the heat seal strength (N / 15 mm) was determined.

[0032] The coating method of the heat seal layer is not particularly limited, and it can be coated with a known coating apparatus and coating system. For example, as the coating apparatus, there are a blade coater, a bar coater, an air knife coater, a curtain coater, a spray coater, a roll coater, a reverse roll coater, a size press coater, a gate roll coater, a gravure coater, a die coater, a blade coater, etc. Further, as the coating system, there are an aqueous coating using a solvent such as water, a solvent-based coating using a solvent such as an organic solvent, etc., but an aqueous coating is preferable from the viewpoints of safety and less environmental load.

[0033] The coating amount per side of the heat seal layer is not particularly limited, but 2.0 g / m 2 or more is preferable, and 2.5 g / m 2 or more is more preferable. If this coating amount is less than 2.0 g / m 2 , it is difficult to form a heat seal layer with a sufficient thickness, and sufficient heat seal strength may not be obtained. The coating amount per side of the heat seal layer tends to improve the heat seal strength as it increases, but if it is too much, the drying energy cost and material cost increase. Therefore, 20 g / m 2 or less is preferable in terms of dry weight, and 10 g / m 2 or less is more preferable. Note that the heat seal layer may be a single layer or may be composed of two or more layers. When the heat seal layer is composed of two or more layers, it is preferable that the total coating amount of all the coating layers is within the above range.

Example

[0034] 「Oil-resistant paper」 (Example 1) Needle kraft pulp (NBKP) with l / D = 0.85 and broadleaf kraft pulp (LBKP) with l / D = 0.34 were mixed at 25 wt% / 75 wt%, and beaten to a freeness of 30°SR by the Shopper - Regler method to prepare a papermaking raw material. Using this papermaking raw material, a paper substrate was made by hand - papering to a dry basis weight of 40 g / m 2 2. An oil - resistant agent was prepared by mixing an acrylic resin (Unidain XP - 8001, non - volatile content 18%, manufactured by Daikin Industries, Ltd.) and starch 1 (Penford Gum 290, non - ionic hydroxyethylated starch, manufactured by Ingredion Inc.) as a water - soluble polymer at a solid content weight ratio of 30 parts by weight / 100 parts by weight to prepare an oil - resistant paint with a solid content concentration of 3.5%. This was impregnated and coated by the size - press method and dried at 100 °C for 1 minute using a KRK rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a sample. The amount of the oil - resistant paint adhered was 2.0 g / m in terms of dry weight, and the amount of the non - fluorine - based oil - resistant agent adhered was 0.5 g / m 2 in terms of dry weight. 2 10. (Example 2)

[0035] Samples were obtained in the same manner as in Example 1 except that the amount of the oil - resistant paint adhered was changed. The amount of the oil - resistant paint adhered was 3.9 g / m in terms of dry weight, and the amount of the non - fluorine - based oil - resistant agent adhered was 0.9 g / m 2 in terms of dry weight. 2 22. (Example 3) LBKP with l / D = 0.34 was beaten to a freeness of 30°SR by the Shopper - Regler method to prepare a papermaking raw material. Using this papermaking raw material, a paper substrate was made by hand - papering to a dry basis weight of 40 g / m 2. The oil - resistant paint was impregnated and coated on the paper substrate in the same manner as in Example 1 to obtain a sample. 2 The amount of the oil - resistant paint adhered was 2.5 g / m in terms of dry weight, and the amount of the non - fluorine - based oil - resistant agent adhered was 0.6 g / m 2 in terms of dry weight. 2 34. (Example 4)

[0036] Samples were obtained in the same manner as in Example 1 except that the amount of the oil - resistant paint adhered was changed. NBKP with l / D = 0.85 and LBKP with l / D = 0.34 were mixed at 50 wt% / 50 wt%, and beaten to a freeness of 30°SR by the Shopper-Riegler method to prepare a papermaking raw material. Using this papermaking raw material, a paper base material was made by hand papermaking so that the dry basis weight would be 40 g / m 2 2. As an oil-resistant agent, an acrylic resin and starch 2 (SK-100, anionic oxidized starch, manufactured by Nippon Corn Starch Co., Ltd.), which is a water-soluble polymer, were mixed at 30 parts by weight / 100 parts by weight to prepare an oil-resistant paint with a concentration of 3.5%. This was impregnated and coated by the size press method and dried at 100°C for 1 minute using a KRK rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a sample. The adhesion amount of the oil-resistant paint was 1.5 g / m 2 2 in terms of dry weight, and the adhesion amount of the non-fluorine-based oil-resistant agent was 0.3 g / m 2 2 in terms of dry weight. (Example 5) The paper base material obtained in Example 4 was used. As the oil-resistant paint, a fatty acid ester resin 1 (BW200, non-volatile content 40%, manufactured by Riken Green Co., Ltd.) was used as the oil-resistant agent, and a water-soluble polymer was impregnated and coated on the paper base material in the same amount as in Example 4 to obtain a sample. The adhesion amount of the oil-resistant paint was 3.0 g / m 2 2 in terms of dry weight, and the adhesion amount of the non-fluorine-based oil-resistant agent was 0.7 g / m 2 2 in terms of dry weight.

[0037] (Example 6) The paper base material obtained in Example 4 was used. As the oil-resistant paint, a fatty acid ester resin 2 (T-EF201, non-volatile content 30%, manufactured by Starlight PMC Co., Ltd.) was used as the oil-resistant agent, and a water-soluble polymer was impregnated and coated on the paper base material in the same amount as in Example 4 to obtain a sample. The adhesion amount of the oil-resistant paint was 2.5 g / m 2 2 in terms of dry weight, and the adhesion amount of the non-fluorine-based oil-resistant agent was 0.6 g / m 2 2 in terms of dry weight. (Example 7) The paper base material obtained in Example 1 was used. The oil-resistant paint was prepared in the same manner as in Example 4 and impregnated and coated on the paper base material to obtain a sample. The adhesion amount of the oil-resistant paint was 1.9 g / m in dry weight 2 and the adhesion amount of the non-fluorine-based oil-resistant agent was 0.4 g / m in dry weight 2 .

[0038] (Example 8) The paper substrate obtained in Example 1 was used. As the oil-resistant agent, an acrylic resin and polyvinyl alcohol (28-98, manufactured by Kuraray Co., Ltd.), which is a water-soluble polymer, were mixed at 30 parts by weight / 100 parts by weight to prepare an oil-resistant paint with a concentration of 3.5%. This was impregnated and coated by the size press method and dried at 100 °C for 1 minute using a KRK rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a sample The adhesion amount of the oil-resistant paint was 2.1 g / m in dry weight 2 and the adhesion amount of the non-fluorine-based oil-resistant agent was 0.5 g / m in dry weight 2 . (Example 9) The papermaking raw materials were prepared in the same manner as in Example 4. Using this papermaking raw material, a paper substrate was prepared by hand papermaking so that the dry basis weight would be 50 g / m 2 . The oil-resistant paint was impregnated and coated on the paper substrate in the same manner as in Example 1 to obtain a sample The adhesion amount of the oil-resistant paint was 2.2 g / m in dry weight 2 and the adhesion amount of the non-fluorine-based oil-resistant agent was 0.5 g / m in dry weight 2 . (Example 10) The papermaking raw materials were prepared in the same manner as in Example 4. Using this papermaking raw material, a paper substrate was prepared by hand papermaking so that the dry basis weight would be 102 g / m 2 . The oil-resistant paint was impregnated and coated on the paper substrate in the same manner as in Example 1 to obtain a sample The adhesion amount of the oil-resistant paint was 2.9 g / m in dry weight 2 and the adhesion amount of the non-fluorine-based oil-resistant agent was 0.7 g / m in dry weight 2 .

[0039] (Example 14) A sample was obtained in the same manner as in Example 1, except that the solid content weight ratio of the acrylic resin and starch 1 as the oil-resistant agent was 10 parts by weight / 100 parts by weight The adhesion amount of the oil-resistant paint was 1.9 g / m in dry weight2 The adhesion amount of the non-fluorine-based oil-resistant agent was 0.2 g / m in dry weight. 2 It was as follows. (Example 15) A sample was obtained in the same manner as in Example 1, except that the solid content weight ratio of the acrylic resin and starch 1 as the oil-resistant agent was 40 parts by weight / 100 parts by weight. The adhesion amount of the oil-resistant paint was 2.1 g / m in dry weight. 2 The adhesion amount of the non-fluorine-based oil-resistant agent was 0.6 g / m in dry weight. 2 It was as follows.

[0040] "Heat-sealable oil-resistant paper" (Example 11) A sample was obtained by applying a polyolefin resin (Zeicen AC, non-volatile content 30%, glass transition temperature 51 °C, manufactured by Sumitomo Seika Chemical Co., Ltd.) as a heat-sealing agent to the processed surface of the oil-resistant paper produced in Example 2 by bar coating. The adhesion amount of the heat-sealing layer was 2.6 g / m in dry weight. 2 It was as follows. (Example 12) A sample was obtained by applying a heat-sealing agent to the processed surface of the oil-resistant paper produced in Example 10 in the same manner as in Example 11. The adhesion amount of the heat-sealing layer was 7.1 g / m in dry weight. 2 It was as follows. (Example 13) A sample was obtained by applying the same heat-sealing agent to the same oil-resistant paper as in Example 12 in the same manner. The adhesion amount of the heat-sealing layer was 3.6 g / m in dry weight. 2 It was as follows.

[0041] (Comparative Example 1) NBKP with l / D = 0.85 and LBKP with l / D = 0.55 were mixed at 25 wt% / 75 wt%, and beaten to a drainage degree of 30 °SR by the Shopper-Riegler method to prepare a papermaking raw material. Using this papermaking raw material, a paper substrate was prepared by hand papermaking so that the dry basis weight became 40 g / m. 2 The oil-resistant paint was impregnated and coated in the same manner as in Example 2 to obtain a sample. The adhesion amount of the oil-resistant paint was 2.8 g / m in dry weight.2 The adhesion amount of the non-fluorine-based oil-resistant agent was 0.6 g / m in terms of dry weight. 2 It was as follows. (Comparative Example 2) NBKP with l / D = 0.85 and LBKP with l / D = 0.34 were mixed at 80 wt% / 20 wt%, and beaten to a drainage degree of 30°SR by the Schopper-Riegler method to prepare a papermaking raw material. Using this papermaking raw material, a paper substrate was produced by hand papermaking so that the dry basis weight became 40 g / m. 2 The oil-resistant paint was impregnated and coated in the same manner as in Example 2 to obtain a sample. The adhesion amount of the oil-resistant paint was 2.2 g / m in terms of dry weight. 2 The adhesion amount of the non-fluorine-based oil-resistant agent was 0.5 g / m in terms of dry weight. 2 It was as follows.

[0042] (Comparative Example 3) The paper substrate obtained in Example 4 was used. Instead of the oil-resistant paint, a coating liquid containing only starch 1, which is a water-soluble polymer, without adding an oil-resistant agent, was prepared and impregnated and coated by the size press method, and dried at 100°C for 1 minute using a KRK rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain a sample. The adhesion amount of the water-soluble polymer was 1.7 g / m in terms of dry weight. 2 It was as follows. (Comparative Example 4) A papermaking raw material was prepared in the same manner as in Example 4. Using this papermaking raw material, a paper substrate was produced by hand papermaking so that the dry basis weight became 15 g / m. 2 The oil-resistant paint was impregnated and coated in the same manner as in Example 2 to obtain a sample. The adhesion amount of the oil-resistant paint was 2.0 g / m in terms of dry weight. 2 The adhesion amount of the non-fluorine-based oil-resistant agent was 0.5 g / m in terms of dry weight. 2 It was as follows.

[0043] The following evaluations were carried out on the obtained paper substrates, oil-resistant papers, and heat-seal oil-resistant papers. The results of the oil-resistant papers are shown in Tables 1 and 2, and the results of the heat-seal oil-resistant papers are shown in Table 3. (Evaluation Method) · Drainage degree (Schopper-Riegler) It was measured in accordance with JIS P8121-1:2012. ·Grammage Measured in accordance with JIS P8124:2011. ·Air permeability resistance (Oka method) Measured in accordance with JIS P8117:2009 using an Oka air permeability resistance smoothness measuring instrument (manufactured by Asahi Seiko Co., Ltd.). ·Tensile strength Measured in accordance with JIS P8113:2006.

[0044] ·Drainage degree of disintegration The oil-resistant paper was disintegrated by the method specified in JIS P8220-1:2012 and measured in accordance with JIS P8121-2:2012. ·Oil barrier property, unevenness of oil barrier property In accordance with the "Paper and Paperboard - Oil Spreading Degree Test Method - Kit Method" described in J.TAPPI No.41:2000, the kit values were measured for 5 test pieces to evaluate the oil barrier property. Also, based on the following evaluation criteria, the unevenness of the oil barrier property was evaluated from the liquid number of the highest value of the kit number without penetration for each of the 5 test pieces. (Evaluation criteria for unevenness of oil barrier property) 〇: The same liquid number for 3 or more pieces, and the difference in liquid numbers is within 1 point. ×: The same liquid number for 2 or fewer pieces, or the difference in liquid numbers is 2 points or more.

[0045] ·Opacity change rate (Irregular kit method) Using rapeseed oil (primary reagent) as the test liquid, the test liquid was dropped onto the oil-resistant paper conditioned at 23°C and 50% RH for 10 hours in a circular shape with a diameter of 5 cm or more. After leaving it for 3 hours in an environment of 23°C and 50% RH, the rapeseed oil on the surface was wiped off. For the location where the rapeseed oil was dropped, the opacity was measured before and after oil contact in accordance with JIS P8149:2000 using a spectrophotometric whiteness meter / color difference meter (Nippon Denshoku Industries Co., Ltd., PF7000)), and the opacity change rate was calculated based on the following formula. Opacity change rate = {(O B - O A ) / O B} × 100 O B : Opacity before oil contact O A : Opacity after oil contact

[0046] · Heat seal strength The heat seal surfaces of the heat seal oil-resistant papers with a heat seal layer were brought into contact with each other, and heat sealing was performed at a pressing temperature of 160 °C, a pressing pressure of 98 kPa, and a pressing time of 1 second using a heat seal tester (manufactured by Tester Sangyo Co., Ltd., TP-7018). After heat sealing, the samples were left at 23 °C and 50% RH for 10 minutes. In this atmosphere, using a tensilon universal testing machine RTG-1210 (A&D Co., Ltd.), the sealed part of the measurement sample was peeled at a tensile speed of 300 mm / min, and the heat seal strength (N / 15 mm) was determined.

[0047]

Table 1

[0048]

Table 2

[0049]

Table 3

[0050] · Results From Examples 1 to 3 and Comparative Examples 1 and 2, it was confirmed that oil-resistant papers containing 30% by weight or more of hardwood pulp with an l / D of 0.50 or less as raw material pulp have less unevenness in oil resistance and can uniformly adhere an oil-resistant paint. From Examples 4 to 6 and Comparative Example 3, it was confirmed that the specific paper base material of the present invention can uniformly impregnate and coat an oil-resistant paint regardless of the type of non-fluorine-based oil-resistant agent and has excellent oil barrier properties. However, with regard to oil penetration prevention, it was confirmed that an acrylic non-fluorine-based oil-resistant agent is excellent. From Examples 1, 7, and 8, it was confirmed that the specific paper base material of the present invention can be uniformly coated with an oil-resistant paint regardless of the type of water-soluble polymer and has excellent oil resistance. From Examples 9, 10, and Comparative Example 4, it was confirmed that the oil-resistant paper of the present invention has practical oil resistance and tensile strength over a wide basis weight. From Examples 1, 14, and 15, it was confirmed that the oil resistance can be controlled by the ratio of the water-soluble polymer and the non-fluorine-based oil-resistant agent. From Examples 11 to 13, it was confirmed that the heat-sealable oil-resistant paper obtained by coating a heat-sealing layer on the oil-resistant paper of the present invention has practical oil resistance and heat-sealing strength.

Claims

1. The oil-resistant paper has an oil-resistant paint containing a non-fluorine-based oil-resistant agent and a water-soluble polymer impregnated in a paper substrate, The paper base material has a basis weight of 20 g / m ２ or more, contains 30% by weight or more of hardwood pulp with an average ratio (l / D) of the lumen width (l) to the fiber width (D) of 0.50 or less as the raw material pulp, and the Schopper-Riegler drainage degree of the pulp constituting the paper base material is 25°SR or more and 45°SR or less, wherein the non-fluorine-based oil-resistant agent contains an acrylic resin.

2. The adhesion amount of the oil-resistant paint is 1.3 g / m in terms of dry weight ２ or more, The oil-resistant paper according to Claim 1, wherein the Kit value measured by J. TAPPI No. 41:2000 on the impregnated surface is 2 or more.

3. The oil-resistant paper according to Claim 1, wherein an oil resistance test is performed by an irregular Kit method, and the opacity change rate before and after oil contact is 10% or less. (Irregular Kit method) Using rapeseed oil (primary reagent) as the test liquid, the test liquid is dropped onto the one conditioned at 23°C and 50% RH for 10 hours, left standing at 23°C and 50% RH for 3 hours, and then the rapeseed oil on the surface is wiped off. The opacity change rate is calculated based on the following formula from the opacity before oil contact. Opacity change rate = { (OB - OA) / OB} × 100 OB: Opacity before oil contact OA: Opacity after oil contact

4. The oil-resistant paper according to Claim 1, wherein the drainage freeness is 250 ml CSF or more and 500 ml CSF or less.

5. The oil-resistant paper according to Claim 1, wherein the water-soluble polymer contained in the oil-resistant paint is one or more selected from starch-based, acrylic resin, and polyvinyl alcohol-based resins.

6. The oil-resistant paper according to Claim 1, wherein the tensile strength is 1.5 kN / m or more.

7. A heat-sealable oil-resistant paper having a heat-sealing layer on at least one side of the oil-resistant paper according to any one of Claims 1 to 6.

Images