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

Abstract

To provide oil-resistant paper using a non-fluorine-based oil-resistant agent.SOLUTION: An oil-resistant paper comprises a paper substrate, which is impregnated with an oil-resistant coating containing a non-fluorine-based oil-resistant agent and a water-soluble polymer. The paper substrate has a basis weight of 20 g / m2 or more, and a freeness of 250 ml CSF or more and 500 ml CSF or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a greaseproof paper and a heat-sealable greaseproof paper having a heat-sealable layer. [Background technology]

[0002] Greaseproof paper is paper that has the function of preventing the penetration of oil. Greaseproof paper is widely used, for example, as packaging material for ready-made meals such as fried chicken and other fried foods, and as bags for packing hamburgers, French fries, fried chicken, etc. at fast food restaurants, convenience stores, etc. Conventionally, the majority of greaseproof paper has been made by coating a paper base with a fluororesin-based oil-proofing agent such as a perfluorohydrocarbon acrylate or a perfluorohydrocarbon phosphate ester. However, it has been confirmed that fluorine-based greaseproof paper coated with fluorine resin-based greaseproofing agents generates perfluoroalcohols, which are highly accumulating in the environment, when heated to 100-180°C. Furthermore, when greaseproof paper containing these fluorine resin-based greaseproofing agents is incinerated after use, fluorine compounds such as perfluorooctanoic acid and perfluorosulfonic acid are generated, raising concerns about adverse health effects on animals, including humans, and the environment. Furthermore, since other low-molecular-weight fluorine compounds are generally difficult to decompose, greaseproof paper that does not contain fluorine compounds is desired, especially for food packaging applications.

[0003] Greaseproof paper for food packaging is required to have oil-resistance properties such as oil barrier properties that prevent oil from passing through the paper and leaking to the other side, and oil-penetration prevention properties that prevent oil from spreading to the surface of the paper and causing the paper to not show an oil-stained appearance (discoloration of the soaked area).Furthermore, greaseproof paper for food packaging is required to make it difficult to see the contents from the outside when food is packaged, to be free of harmful substances, to be disintegrable (recyclable) and to be reusable as a resource, etc.

[0004] Patent Document 1 proposes grease-resistant paper in which a water-soluble polymer is applied to a base material made of natural papermaking fibers containing a filler. Patent Document 1 aims to achieve recyclability without using fluorine-based compounds, but provides the desired grease-resistant paper by providing a water-soluble polymer layer as an oil-resistant layer on a base material with high air resistance obtained by highly beating natural papermaking fibers to a freeness of 85 to 90°SR. Patent Document 2 proposes grease-resistant paper in which an oil-resistant layer consisting of a non-fluorine-based oil-proofing agent and polyethylene wax with an average particle size of 1 to 20 μm is applied to a paper base material. Patent Document 2 proposes acrylic resin, starch, and polyvinyl alcohol as the non-fluorine-based oil-proofing agents, and provides grease-resistant paper that addresses the issues of operability and cost associated with applying these oil-proofing agents by setting the smoothness and air permeability of the paper base material within specified ranges. Patent Document 3 describes an oil-resistant paper that does not use fluorine-based compounds, in which the raw materials for the paper base are 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 paper made is 0.45 g / cm 3 More than 0.75g / cm 3 The following paper has been proposed as an oil-resistant paper with a stick-type sizing degree of 5 seconds or more, in which a styrene-acrylic copolymer resin and paraffin wax are applied to the paper base material in a blending ratio of 90:10 to 10:90 (mass ratio). Patent Document 3 explains that the styrene-acrylic copolymer resin provides film-forming properties to the oil-resistant layer, and the paraffin wax improves oil resistance by existing in the voids in the paper base material.

[0005] Patent Documents 4 and 5 propose oil-resistant paper that uses one or more of modified starch, amylose, and polyvinyl alcohol as an oil-resistant agent. The paper base material is mainly made of pulp fibers, and Patent Document 4 uses an impregnation method to apply the oil-resistant layer, while Patent Document 5 uses a spray coating method between the layers of multi-layer paper. Neither document specifies the basis weight of the paper base material, but the examples show a basis weight of 200 to 300 g / m 2 This is implemented in the above basis weight range. Patent Document 6 describes a method in which a paper substrate is coated with a polylactic acid resin, a polyvinyl alcohol resin, and / or a starch compound in a ratio of 70:30 to 98:2 (dry weight ratio) at 3 g / m2 More than 20g / m 2 The following grease-resistant papers have been proposed: Patent Document 6 provides grease-resistant paper that has heat-sealing properties while also taking into consideration the prevention of the generation of harmful substances when burned and decomposition when released into the environment, by blending a biodegradable resin without using a fluorine-based compound in the oil-resistant layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4520138 [Patent Document 2] Patent No. 5994455 [Patent Document 3] Japanese Patent Publication No. 2020-122250 [Patent Document 4] Japanese Patent Application Laid-Open No. 2005-29943 [Patent Document 5] Patent No. 4604466 [Patent Document 6] Japanese Patent Application Publication No. 2020-128616 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide greaseproof paper using a non-fluorine-based greaseproofing agent, and to provide greaseproof paper with uniform quality and little variation in oil resistance across a wide range of paper base materials. [Means for solving the problem]

[0008] The means for solving the problems of the present invention are as follows. 1. A paper substrate 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 20g / m 2The greaseproof paper is characterized by the above, containing 30% by weight or more of hardwood pulp as raw material pulp, with an average ratio (l / D) of lumen width (l) to fiber width (D) of 0.50 or less, and the Schopper-Riegler freeness of the pulp constituting the paper base material is 25°SR or more and 45°SR or less. 2. The amount of oil-resistant paint applied is 1.3 g / m2 in dry weight. 2 That's all, 1. The grease-resistant paper according to 1, wherein the Kit value of the impregnated surface measured according to J.TAPPI No. 41:2000 is 2 or more. 3. Oil-resistant paper as described in 1 or 2, which has an oil resistance test using the irregular kit method and shows a change in opacity of 10% or less before and after contact with oil. (Atypical kit method) Rapeseed oil (first-class reagent) is used as the test liquid, and the test liquid is dropped onto a sample that has been conditioned for 10 hours at 23°C and 50% RH. After leaving the sample at 23°C and 50% RH for 3 hours, the rapeseed oil on the surface is wiped off. The rate of change in opacity is calculated from the opacity before contact with the oil using the following formula. Opacity change rate = {(O B -O A ) / O B}×100 O B : Opacity before contact with oil O A :Opacity after contact with oil 4. The greaseproof paper according to any one of 1 to 3, having a maceration freeness 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-based, and polyvinyl alcohol-based resins. 6. Greaseproof paper according to any one of 1. to 5., having a tensile strength of 1.5 kN / m or more. 7. Heat-sealable grease-resistant paper having a heat-seal layer on at least one side of the grease-resistant paper according to any one of 1. to 6. [Effects of the Invention]

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

[0010] Greaseproof paper The oil-resistant paper of the present invention has a paper base impregnated with an oil-resistant paint containing a non-fluorinated oil-proofing agent and a water-soluble polymer. Whether or not the paper is impregnated with the paint 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 an internal cavity called a lumen. l / D is a value that indicates the ratio of lumen width to fiber thickness, with a smaller value indicating a smaller lumen and thicker fiber wall. Pulp l / D can be measured using the following procedure. 1. Dilute the pulp suspension to a concentration of 0.05%. 2. Using a dropper tube, drip the diluted solution onto a clean glass slide, disperse the fibers evenly using a dissecting needle if necessary, and allow to dry. 3. Drop three drops of staining solution C onto the fibers dispersed on the slide glass, place a cover glass on top taking care not to trap air bubbles, remove excess staining solution with blotting paper, and prepare a preparation. 4. Observe the preparation using an optical microscope, move the preparation horizontally or vertically on a movable stage, measure the fiber width (D) and lumen width (l) at the center of the pulp lengthwise, and calculate l / D. When preparing paper stock, the l / D of 100 or more pulps of the pulp to be blended is determined using the above method, and the average value can be used as the l / D of the pulp. From the paper made, the paper is disintegrated in the same manner as in preparing a slurry for measuring the disintegration freeness of paper, and 200 or more pulps are distinguished using a dye solution that produces different colors depending on the tree species, etc., and the l / D is determined using the above method, thereby determining the amount of hardwood pulp blended and the l / D of the pulp.

[0012] (Hardwood pulp with l / D of 0.50 or less) Hardwood pulp with an l / D ratio of 0.50 or less forms low-density sheets with thick fiber walls that are resistant to crushing. Although the degree of this varies depending on the wood species and other pulp blends, using a stock containing 30% by weight or more of hardwood pulp with an average lumen width (l) to fiber width (D) ratio (l / D) of 0.50 or less as the raw pulp material allows for a low density, i.e., highly breathable, paper base material to be obtained even after the beating process required to obtain the paper strength required in the manufacturing process. The high breathability of the paper base material allows oil-resistant paint to be quickly impregnated and uniformly applied throughout the entire paper base material, thereby minimizing unevenness in the oil resistance of the resulting grease-resistant paper. For hardwood pulp with an l / D ratio of 0.50 or less, the l / D ratio is preferably 0.45 or less, and more preferably 0.40 or less.

[0013] Hardwood pulp having an l / D of 0.50 or less is not particularly limited, and examples thereof include mechanical pulp (MP), thermomechanical pulp (TMP), sulfite pulp (SP), kraft pulp (KP), and their bleached pulps (BP) and unbleached pulps (UP), and these can be used alone or in combination of two or more. Of these, it is preferable to use kraft pulp (KP), which has excellent strength.

[0014] (Other pulps) Other pulps that can be combined with hardwood pulp having an l / D of 0.50 or less include, without particular limitation, hardwood pulp having an l / D of more than 0.50, softwood pulp, refined pulp such as regenerated cellulose, mercerized pulp, dissolving pulp, and non-wood pulp such as bast fibers such as flax, kenaf, paper mulberry, and mitsumata, hard fibers such as bagasse, bamboo, and esparto, seed fibers such as cotton linters, and leaf vein fibers such as Manila hemp and sisal. The pulp that constitutes the paper base material may be a mixture of hardwood pulp and other pulp and then beaten, or the hardwood pulp and other pulp may be beaten separately and then mixed. The paper base material of the present invention contains 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 of hardwood pulp having an l / D of 0.50 or less relative to the total pulp used as the papermaking raw material.

[0015] The paper base material of the present invention has a Shopper-Riegler freeness of 25°SR or more and 45°SR or less for the pulp constituting the paper base material. The pulp constituting the paper base material refers to all pulp contained in the paper base material. Paper base materials with a Shopper-Riegler freeness of less than 25°SR have low strength, and therefore breakage of the paper base material and deterioration of the paper base material's formation are significant when impregnated with an oil-resistant coating, which can result in uneven oil resistance. Furthermore, if the Shopper-Riegler freeness exceeds 45°SR, uneven absorption of the paper base material occurs when impregnated with an oil-resistant coating, which can result in uneven oil resistance of the greaseproof paper. The Shopper-Riegler freeness 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 may be added to the paper base material as needed, such as fillers, pigments, sizing agents, coagulants, fluorescent whitening agents, aluminum sulfate, retention aids, drainage aids, dry strength agents, wet strength agents, coloring dyes, coloring pigments, and waterproofing agents, which may be used alone or in combination.

[0017] (Manufacturing method) The paper substrate can be produced using a method known in the art for papermaking, such as a Fourdrinier paper machine, a cylinder paper machine, a short wire paper machine, a twin-wire paper machine, an on-top hybrid paper machine, or a gap former machine.

[0018] The paper base weight is 20 g / m 2 The basis weight is 20 g / m 2 If the paper base is less than 20g / m², the tensile strength will be weak and the paper base may break during papermaking and oil-resistant layer processing. Furthermore, the lower the basis weight of the base material, the more likely it is that uneven adhesion of the oil-resistant agent will occur, which is thought to be due to the influence of the pulp fiber formation, and this will cause uneven oil resistance. The basis weight of the paper base material should be 20g / m². 2 There is no particular limitation as long as it is equal to or more than 30 g / m. 2 More than 400g / m 2 It can be as follows:

[0019] From the viewpoint of oil-proofing agent permeability, the paper substrate preferably has an Oken air resistance of 100 seconds or less. The Oken air resistance of the paper substrate is more preferably 50 seconds or less, even more preferably 30 seconds or less, and even more preferably 20 seconds or less. The Oken air resistance of the paper substrate 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, but does not contain a fluorine-based oil-resistant agent. Furthermore, the paint containing a non-fluorine-based oil-resistant agent preferably does not contain a low-molecular-weight fluorine compound, and more preferably does not contain a fluorine-based compound.

[0021] (Non-fluorinated oil resistant agent) Non-fluorine-based oil-proofing agents can be used without any particular limitation, and examples thereof include natural polymers such as starch, cellulose derivatives, gelatin, casein, and soybean protein, and synthetic polymers such as polyvinyl alcohol, polyisoprene, and chloroprene polymers or copolymers, polydienes, polyalkenes, polymers or copolymers of vinyl monomers, synthetic rubber latex, polyurethane resins, polyester resins, polyamide resins, olefin-maleic anhydride resins, silicone resins, acrylic resins, melamine resins, fatty acid ester resins, vegetable waxes, animal waxes, mineral waxes, and petroleum waxes, and these can be used alone or in combination of two or more. Among these, acrylic resins and fatty acid ester resins are preferred from the viewpoint of oil resistance, and acrylic resins are more preferred from the viewpoint of oil penetration prevention.

[0022] (Water-soluble polymer) The water-soluble polymer acts as a hydrophilic binder that fixes the non-fluorinated oil-proofing agent to the pulp fibers of the paper substrate without inhibiting the performance of the oil-proofing agent. Examples of water-soluble polymers include anionic polyelectrolyte salts such as carboxyalkylcellulose salts, alginates, pectinates, polyacrylates, polymethacrylates, carboxyalkylated starch, phosphated starch, anionic modified polyvinyl alcohol resins, and anionic polyacrylamides; nonelectrolytes such as methylcellulose, hydroxyalkylcellulose, polyvinyl alcohol resins, polyvinylpyrrolidone, polyalkylene oxides, polyvinyl alkyl ethers, hydroxyalkylated starch, oxidized starch, and pregelatinized starch; water-soluble polysaccharides such as guar gum, tolanthus gum, xanthan gum, gum arabic, carrageenan, galactomannan, pullulan, dextran, and dextrin; and water-soluble proteins such as gelatin and casein. These may be used singly or in combination of two or more. Among these, from the viewpoints of processability, oil resistance, and material cost, starch-based materials (carboxyalkylated starch, phosphated starch, hydroxyalkylated starch, oxidized starch, pregelatinized starch), acrylic resins, and polyvinyl alcohol-based resins are preferred, with acrylic resins being even more preferred due to their excellent oil resistance. Furthermore, it is preferable that the water-soluble polymer has a neutral charge or the same charge as the non-fluorinated oil-proofing agent. However, when an aqueous solution of 10% by weight of the non-fluorinated oil-proofing agent and 10% by weight of the water-soluble polymer is prepared, those that do not form a uniform aqueous phase (for example, due to phase separation, aggregation, etc.) cannot be used.

[0023] From the viewpoint of material costs, the oil-resistant paint preferably contains 5 to 100 parts by weight of a non-fluorinated 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 may also contain additives such as surfactants, antifoaming agents, surface sizing agents, paper strength agents, water retention agents, thickeners, release agents, and anti-slip agents, as long as the additives do not impair the performance of the paint.

[0024] The oil-resistant paper of the present invention preferably has an oil resistance of 2 or more in terms of kit value as defined in J TAPPI No. 41:2000 on the impregnated surface. If the oil resistance is less than 2, oil from the food stored inside may seep out to the outside, causing the outer surface to become stained with oil. This kit value may be 3 or more, 4 or more, or 5 or more. Here, the kit value is expressed as a number from 1 to 12, with a higher number indicating better oil resistance (oil barrier properties). Even if the kit value is low, the grease-resistant paper of the present invention has excellent oil penetration prevention properties, is less susceptible to oil penetration, and is less susceptible to discoloration. The upper limit of the kit value of the grease-resistant paper of the present invention can be, for example, 7 or less, 6 or less, or 5 or less. In order to prevent paper breakage during papermaking, etc., the grease-resistant paper of the present invention preferably has a tensile strength measured in accordance with JIS P8113:2006 of 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 method of impregnation of the oil-resistant paint is not particularly limited, and known impregnation methods and coating methods can be used. Specifically, an appropriate method can be selected from impregnation coating using a mangle, size press, etc., and surface coating using a gate roll coater, blade coater, bar coater, champlex coater, gravure coater, die coater, curtain coater, air knife coater, spray coater, etc. Among these, size press is preferred because it has excellent paint impregnation properties. The oil-resistant paint may be either a water-based paint using a solvent such as water or a solvent-based paint using a solvent such as an organic solvent, but from the viewpoint of safety and hygiene, a water-based paint is preferred.

[0026] To obtain greaseproof paper with a kit value of 2 or higher, the amount of greaseproof paint applied must be 1.3 g / m2 in dry weight. 2 More than 1.4g / m is preferable. 2 More preferably, 1.5 g / m 2 The upper limit of the amount of oil-resistant paint applied is not particularly limited, but for example, it is 10 g / m2 in dry weight. 2 The oil-resistant paint should preferably have a dry weight of 10 g / m2 Even if the temperature exceeds this range, the oil resistance hardly improves any more, and the cost also increases. The amount of non-fluorine-based oil-resistant agent adhered varies depending on the proportion of non-fluorine-based oil-resistant agent in the oil-resistant paint, but the amount of non-fluorine-based oil-resistant agent adhered is 0.2 g / m2 in dry weight. 2 It is preferable that the content is 0.25 g / m or more. 2 More preferably, 0.3 g / m or more 2 The upper limit of the amount of the non-fluorine-based oil-resistant agent to be applied is not particularly limited, but for example, it is preferably 5 g / m2 in dry weight. 2 The oil-resistant paint should have a dry weight of 5 g / m or less. 2 Even if the temperature exceeds this range, the oil resistance hardly improves any more, and the cost also increases.

[0027] The grease-resistant paper of the present invention preferably undergoes an oil resistance test using the modified kit method described below, and the opacity change rate before and after contact with oil is 10% or less. When oil penetrates into the grease-resistant paper, light scattering decreases, resulting in a decrease in opacity (becoming transparent). Therefore, the smaller the opacity change rate, the better the oil penetration prevention ability. For the grease-resistant paper of the present invention, this opacity change rate is more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, even more preferably 6% or less, even more preferably 5% or less, and even more preferably 4% or less. (Atypical kit method) Rapeseed oil (first-class reagent) is used as the test liquid, and the test liquid is dropped onto a sample that has been conditioned for 10 hours at 23°C and 50% RH. After leaving the sample at 23°C and 50% RH for 3 hours, the rapeseed oil on the surface is wiped off. The rate of change in opacity is calculated from the opacity before contact with the oil using the following formula. Opacity change rate = {(O B -O A ) / O B}×100 O B : Opacity before contact with oil O A :Opacity after contact with oil

[0028] The greaseproof paper of the present invention preferably has a remaced freeness of 250 ml CSF or more and 500 ml CSF or less. The remaced freeness is the Canadian standard freeness measured in accordance with JIS P8121-2:2012 after remacing the greaseproof paper using the method specified in JIS P8220-1:2012. The remaced freeness 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-sealed oil-resistant paper" The heat-sealable grease-resistant paper of the present invention has a heat-sealable layer on at least one side of the grease-resistant paper described above. The heat-sealable layer can be provided on both sides, but if provided on only one side, it is preferably provided on the processed surface impregnated with the oil-resistant paint. When applying a heat-sealing agent to the grease-resistant paper, the heat-sealing layer may not be applied uniformly in the case of grease-resistant paper with a high kit value due to the relationship between the wettability of the heat-sealing agent and the grease-resistant paper. Therefore, when producing heat-sealable grease-resistant paper, if the heat-sealing layer cannot be applied uniformly, it is necessary to adjust the viscosity and solvent composition of the heat-sealing agent coating solution.

[0030] (heat seal layer) The heat-seal layer is formed by applying a coating material containing a thermoplastic resin with heat-sealing properties to at least one surface of the greaseproof paper. The thermoplastic resin contained in the heat-seal layer can be any known resin without any particular limitations, and examples thereof include polyethylene-based resins and polypropylene-based resins. Examples of polyethylene-based resins 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, ionomers, derivatives thereof, and mixtures thereof. Examples of polypropylene-based resins include polypropylene (PP) homopolymer, random polypropylene (random PP), block polypropylene (block PP), chlorinated polypropylene, carboxylic acid-modified polypropylene, derivatives thereof, and mixtures thereof. Among these, resins with a glass transition temperature of 100°C or less are preferably used. The thermoplastic resin preferably has a glass transition temperature of −20° C. or more and 85° C. or less, and a melting point of 70° C. or more and 140° C. or less. The glass transition temperature and melting point refer to the midpoint glass transition temperature and peak melting temperature, respectively, measured in accordance with JIS P7121:2012.

[0031] In addition to the thermoplastic resin, the heat seal layer may also contain surfactants, waxes, inorganic pigments, dispersants, thickeners, etc., as needed. The heat seal layer preferably has a heat seal strength measured by the following method of 2.3 N / 15 mm or more, more preferably 2.9 N / 15 mm or more. (Measurement conditions) The heat-sealable surfaces of the heat-sealable greaseproof papers were brought into contact with each other and heat-sealed using a heat seal tester (TP-7018, manufactured by Tester Sangyo Co., Ltd.) at a pressure of 160°C, a pressure of 98 kPa, and a pressure time of 1 second. After heat sealing, the sample was left at 23°C and 50% RH for 10 minutes. Under this atmosphere, the sealed portion of the sample was peeled off at a pulling rate of 300 mm / min using a Tensilon universal testing machine RTG-1210 (A&D Co., Ltd.), and the heat seal strength (N / 15 mm) was determined.

[0032] The coating method for the heat seal layer is not particularly limited, and coating can be performed using a known coating device and coating system. Examples of coating devices include blade coaters, bar coaters, air knife coaters, curtain coaters, spray coaters, roll coaters, reverse roll coaters, size press coaters, gate roll coaters, gravure coaters, die coaters, and blade coaters. Examples of coating systems include aqueous coating using a solvent such as water, and solvent-based coating using a solvent such as an organic solvent, but aqueous coating is preferred from the viewpoints of safety and environmental impact.

[0033] The amount of the heat seal layer attached on one side is not particularly limited, but it is preferably 2.0 g / m2 in dry weight. 2 More than 2.5g / m is preferable. 2 More preferably, the coating amount is 2.0 g / m or more. 2 If the thickness is less than 20 g / m2, it is difficult to form a heat seal layer of sufficient thickness, and sufficient heat seal strength may not be obtained. The more the amount of heat seal layer attached per side, the better the heat seal strength tends to be. However, if it is too much, the energy cost for drying and the material cost increase. Therefore, it is recommended to use a dry weight of 20 g / m2 or more. 2 Less than 10 g / m is preferred 2 The following is more preferable. 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 weight of all coating layers is within the above range. [Example]

[0034] Greaseproof paper Example 1 A papermaking stock was prepared by mixing softwood kraft pulp (NBKP) with l / D = 0.85 and hardwood kraft pulp (LBKP) with l / D = 0.34 at a ratio of 25% by weight and 75% by weight, and beating the mixture to a freeness of 30°SR according to the Schopper-Riegler method. This papermaking stock was used to prepare a papermaking stock with a dry basis weight of 40 g / m. 2 The paper base was prepared by hand-making so that An acrylic resin (Unidyne XP-8001, 18% nonvolatile content, Daikin Industries, Ltd.) was used as an oil-resistant agent, and starch 1 (Penford Gum 290, nonionic hydroxyethylated starch, Incredion), a water-soluble polymer, was mixed at a solids weight ratio of 30 parts by weight / 100 parts by weight to prepare an oil-resistant paint with a solids concentration of 3.5%. This was impregnated and coated using a size press method, and then dried at 100°C for 1 minute in a KRK rotary dryer (Kumagaya Riki Kogyo Co., Ltd.) to obtain a sample. The dry weight of oil-resistant paint is 2.0 g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.5 g / m 2 It was.

[0035] Example 2 Samples were obtained in the same manner as in Example 1, except that the amount of oil-resistant paint applied was changed. The dry weight of the oil-resistant paint is 3.9 g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.9 g / m 2 It was. Example 3 A papermaking stock was prepared by beating LBKP with l / D = 0.34 so that the freeness by the Schopper-Riegler method was 30°SR. This papermaking stock was used to prepare a dry basis weight of 40 g / m 2 A paper substrate was prepared by hand-sheeting so that the oil-resistant paint was applied to the paper substrate by impregnation in the same manner as in Example 1 to obtain a sample. The dry weight of the oil-resistant paint is 2.5g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.6 g / m 2 It was.

[0036] Example 4 A 50% by weight mixture of NBKP (l / D = 0.85) and LBKP (l / D = 0.34) was beaten to a freeness of 30°SR by the Schopper-Riegler method to prepare a papermaking stock. This papermaking stock was used to prepare a dry basis weight of 40 g / m 2 The paper base was prepared by hand-making so that An acrylic resin was used as an oil-resistant agent, and starch 2 (SK-100, an anionic oxidized starch, manufactured by Nippon Cornstarch Co., Ltd.), a water-soluble polymer, was mixed at 30 parts by weight and 100 parts by weight to prepare an oil-resistant paint with a concentration of 3.5%. This was impregnated and coated using a size press method, and dried at 100°C for 1 minute in a KRK rotary dryer (manufactured by Kumagaya Riki Kogyo Co., Ltd.) to obtain a sample. The dry weight of oil-resistant paint is 1.5g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.3 g / m 2 It was. Example 5 The paper substrate obtained in Example 4 was used. The oil-resistant paint used fatty acid ester resin 1 (BW200, non-volatile content 40%, manufactured by Riken Green Co., Ltd.) as an oil-resistant agent, and the water-soluble polymer and blending amounts were the same as in Example 4. The paper substrate was impregnated and coated to obtain a sample. The dry weight of oil-resistant paint is 3.0 g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.7 g / m 2 It was.

[0037] Example 6 The paper substrate obtained in Example 4 was used. The oil-resistant paint used fatty acid ester resin 2 (T-EF201, non-volatile content 30%, manufactured by Seiko PMC Corporation) as an oil-resistant agent, and the water-soluble polymer was impregnated and coated onto the paper substrate in the same amounts as in Example 4 to obtain a sample. The dry weight of the oil-resistant paint is 2.5g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.6 g / m 2 It was. Example 7 The paper substrate used was the same as in Example 1. The oil-resistant paint was prepared in the same manner as in Example 4 and was impregnated and coated onto the paper substrate to obtain a sample. The dry weight of oil-resistant paint is 1.9 g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.4 g / m 2 It was.

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

[0039] Example 14 A sample was obtained in the same manner as in Example 1, except that the solid weight ratio of the acrylic resin as the oil-resistant agent to the starch 1 was 10 parts by weight / 100 parts by weight. The dry weight of oil-resistant paint is 1.9 g / m2 The dry weight of the non-fluorine-based oil-resistant agent was 0.2 g / m 2 It was. Example 15 A sample was obtained in the same manner as in Example 1, except that the solid weight ratio of the acrylic resin as the oil-resistant agent to the starch 1 was 40 parts by weight / 100 parts by weight. The dry weight of the oil-resistant paint is 2.1 g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.6 g / m 2 It was.

[0040] "Heat-sealed oil-resistant paper" Example 11 A polyolefin resin (Zaixen AC, non-volatile content 30%, glass transition temperature 51°C, manufactured by Sumitomo Seika Chemicals Co., Ltd.) was applied as a heat sealant to the processed surface of the greaseproof paper produced in Example 2 using a bar coater to obtain a sample. The heat seal layer has a dry weight of 2.6 g / m 2 It was. Example 12 A heat sealing agent was applied to the processed surface of the greaseproof paper prepared in Example 10 in the same manner as in Example 11 to obtain a sample. The dry weight of the heat seal layer is 7.1 g / m 2 It was. Example 13 The same heat sealing agent was applied to the same greaseproof paper as in Example 12 to obtain a sample. The dry weight of the heat seal layer is 3.6 g / m 2 It was.

[0041] (Comparative Example 1) A 25% by weight mixture of NBKP (l / D = 0.85) and LBKP (l / D = 0.55) was beaten to a freeness of 30°SR by the Schopper-Riegler method to prepare a papermaking stock. This papermaking stock was used to prepare a dry basis weight of 40 g / m 2 The paper substrate was prepared by hand-sheeting so that the oil-resistant paint was applied by impregnation coating in the same manner as in Example 2 to obtain a sample. The dry weight of the oil-resistant paint is 2.8 g / m2 The dry weight of the non-fluorine-based oil-resistant agent was 0.6 g / m 2 It was. (Comparative Example 2) A papermaking stock was prepared by mixing NBKP (l / D = 0.85) and LBKP (l / D = 0.34) at a ratio of 80% by weight and 20% by weight, and beating the mixture to a freeness of 30°SR according to the Schopper-Riegler method. This papermaking stock was used to prepare a dry basis weight of 40 g / m 2 The paper substrate was prepared by hand-sheeting so that the oil-resistant paint was applied by impregnation coating in the same manner as in Example 2 to obtain a sample. The dry weight of the oil-resistant paint is 2.2 g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.5 g / m 2 It was.

[0042] (Comparative Example 3) The paper substrate obtained in Example 4 was used. Instead of the oil-resistant paint, a coating solution containing only starch 1, a water-soluble polymer, without blending any oil-resistant agent was prepared, and the coating was impregnation-coated using a size press method, followed by drying at 100°C for 1 minute in a KRK rotary dryer (manufactured by Kumagaya Riki Kogyo Co., Ltd.) to obtain a sample. The dry weight of the water-soluble polymer is 1.7 g / m 2 It was. Comparative Example 4 A papermaking stock was prepared in the same manner as in Example 4. Using this papermaking stock, a paper having a dry basis weight of 15 g / m 2 The paper substrate was prepared by hand-sheeting so that the oil-resistant paint was applied by impregnation coating in the same manner as in Example 2 to obtain a sample. The dry weight of oil-resistant paint is 2.0 g / m 2 The dry weight of the non-fluorine-based oil-resistant agent was 0.5 g / m 2 It was.

[0043] The obtained paper substrate, grease-resistant paper, and heat-sealable grease-resistant paper were evaluated as follows. The results for the grease-resistant paper are shown in Tables 1 and 2, and the results for the heat-sealable grease-resistant paper are shown in Table 3. (Evaluation method) Freeness (Schopper Riegler) Measurements were performed in accordance with JIS P8121-1:2012. ·Basic weight Measurements were performed in accordance with JIS P8124:2011. ·Air permeability resistance (Ouken style) Measurement was carried out in accordance with JIS P8117:2009 using an Oken-type air resistance smoothness measuring instrument (manufactured by Asahi Seiko Co., Ltd.). Tensile strength Measurements were made in accordance with JIS P8113:2006.

[0044] ·Disintegrated freeness The greaseproof paper was disintegrated according to the method specified in JIS P8220-1:2012, and measurements were made in accordance with JIS P8121-2:2012. ·Oil barrier properties, unevenness of oil barrier properties In accordance with "Paper and paperboard - Oil repellency test method - Kit method" described in J.TAPPI No. 41:2000, kit values ​​were measured for five test pieces to evaluate the oil barrier properties. Furthermore, unevenness in oil barrier properties was evaluated using the liquid number with the highest kit number that did not soak into each of the five test pieces, according to the following evaluation criteria. (Evaluation criteria for unevenness of oil barrier properties) 〇: Three or more cards have the same liquid number, and the difference in liquid numbers is within one point. ×: There are two or fewer sheets with the same liquid number, or the difference in liquid numbers is two or more points.

[0045] Opacity change rate (Atypical kit method) Rapeseed oil (first-class reagent) was used as the test liquid, and the test liquid was dropped in a circle with a diameter of 5 cm or more onto greaseproof paper that had been conditioned for 10 hours in an environment of 23°C and 50% RH.The paper was then left for 3 hours in an environment of 23°C and 50% RH, and the rapeseed oil on the surface was then wiped off. The opacity of the area where the rapeseed oil was dropped was measured before and after contact with the oil using a spectrophotometer and color difference meter (PF7000, Nippon Denshoku Industries Co., Ltd.) in accordance with JIS P8149:2000, and the rate of change in opacity was calculated based on the following formula. Opacity change rate = {(O B -O A ) / O B}×100 O B : Opacity before contact with oil O A :Opacity after contact with oil

[0046] Heat seal strength The heat-sealed surfaces of the heat-sealed grease-resistant papers with heat-sealing layers attached were brought into contact with each other, and heat-sealed using a heat-seal tester (TP-7018, manufactured by Tester Sangyo Co., Ltd.) at a pressure of 160°C, a pressure of 98 kPa, and a pressure time of 1 second. After heat sealing, the sample was left at 23°C and 50% RH for 10 minutes. Under this atmosphere, the sealed portion of the sample was peeled off at a pulling rate of 300 mm / min using a Tensilon universal testing machine RTG-1210 (A&D Co., Ltd.), and the heat seal strength (N / 15 mm) was determined.

[0047] [Table 1]

[0048] [Table 2]

[0049] [Table 3]

[0050] ·result From Examples 1 to 3 and Comparative Examples 1 and 2, it was confirmed that oil-resistant paper whose paper base material contains 30% by weight or more of hardwood pulp with an average l / D of 0.50 or less as raw material pulp has little unevenness in oil resistance and can have oil-resistant paint applied evenly. Examples 4 to 6 and Comparative Example 3 confirmed that the specific paper substrate of the present invention can be uniformly impregnated with an oil-resistant paint and has excellent oil barrier properties, regardless of the type of non-fluorinated oil-proofing agent. However, it was confirmed that acrylic non-fluorinated oil-proofing agents are superior in terms of preventing oil penetration. From Examples 1, 7, and 8, it was confirmed that the specific paper substrate 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. Examples 9 and 10 and Comparative Example 4 confirmed that the oil-resistant paper of the present invention has practical oil resistance and tensile strength over a wide range of basis weights. From Examples 1, 14 and 15, it was confirmed that oil resistance can be controlled by adjusting the ratio of the water-soluble polymer to the non-fluorinated oil-proofing agent. From Examples 11 to 13, it was confirmed that the heat-sealable grease-resistant paper of the present invention, which was provided with a heat-seal layer, had practical oil resistance and heat-seal strength.

Claims

1. The paper substrate 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 / m ２ That's all, Greaseproof paper having a maceration freeness of 250 ml CSF or more and 500 ml CSF or less.

2. 2. The oil-resistant paper according to claim 1, wherein the non-fluorine-based oil-resistant agent comprises an acrylic resin.

3. The amount of the oil-resistant paint adhered is 1.3 g / m2 in dry weight. ２ That's all, 2. The greaseproof paper according to claim 1, wherein the impregnated surface has a Kit value of 2 or more as measured according to J. TAPPI No. 41:2000.

4. 2. The oil-resistant paper according to claim 1, wherein the change in opacity before and after contact with oil is 10% or less when the oil resistance test is carried out using the irregular kit method. (Atypical kit method) Rapeseed oil (first-class reagent) was used as the test liquid, and the test liquid was dropped onto a sample that had been conditioned for 10 hours in an environment of 23°C and 50% RH. After leaving the sample in an environment of 23°C and 50% RH for 3 hours, the rapeseed oil on the surface was wiped off. The rate of change in opacity was calculated from the opacity before contact with the oil using the following formula. Opacity change rate = {(OB - OA) / OB} x 100 OB: Opacity before contact with oil OA: Opacity after contact with oil

5. 2. 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 the group consisting of starch-based, acrylic-based, and polyvinyl alcohol-based resins.

6. 2. The greaseproof paper according to claim 1, having a tensile strength of 1.5 kN / m or more.

7. 7. A heat-sealable grease-resistant paper having a heat-seal layer on at least one side of the grease-resistant paper according to any one of claims 1 to 6.

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