Heat-sealable oil-resistant paper

Abstract

To provide a non-fluorine-based heat-sealable oil-resistant paper with excellent oil resistance, breathability, and moisture permeability. [Solution] Oil-resistant paper in which an oil-resistant coating containing a non-fluorine-based oil-resistant agent and a water-soluble polymer is impregnated into a paper substrate, The oil-resistant paper has a heat-seal layer on at least one surface, Air permeability resistance (Wang Research method) of 100 seconds or less, and moisture permeability of 1500 g / m². 2 • Heat-sealable oil-resistant paper with a lifespan of 1 day or more.

Description

[Technical Field]

[0001] This invention relates to oil-resistant paper with heat-sealing properties. [Background technology]

[0002] Oil-resistant paper is paper that has the function of preventing oil from penetrating. Oil-resistant paper is widely used, for example, as packaging material for prepared foods such as fried chicken and other fried foods, and as bags for hamburgers, french fries, and fried chicken in fast food restaurants and convenience stores. Traditionally, oil-resistant paper has mainly consisted of paper substrates coated with fluorine-based oil-resistant agents such as perfluorinated hydrocarbon acrylates or perfluorinated hydrocarbon phosphate esters. However, it has been confirmed that oil-resistant paper coated with fluorine-based oil repellents generates perfluoroalcohol, which has high environmental bioaccumulation potential, when heated to 100-180°C. Furthermore, when oil-resistant paper using these fluorine-based oil repellents is incinerated after use, fluorine compounds such as perfluorooctanoic acid and perfluorosulfonic acid are generated, raising concerns about health hazards to humans and animals, as well as adverse effects on the environment. In addition, other low-molecular-weight fluorine compounds are generally difficult to decompose, so oil-resistant paper that does not use fluorine compounds is particularly desired for food packaging applications.

[0003] Oil-resistant paper for food packaging is required to have oil barrier properties that prevent oil from passing through the paper and leaking to the other side, and oil penetration prevention properties that prevent the oil from spreading easily across the surface of the oil-resistant paper, thus preventing it from appearing as if it has been soaked in oil (discoloration of the soaked area). Furthermore, for safety, hygiene, and taste considerations, oil-resistant paper for food packaging is required to be breathable so that steam released from hot food does not condense inside the packaging paper.

[0004] Patent Document 1 describes a substrate made of natural fibers for papermaking containing fillers, coated with a water-soluble polymer, resulting in an air permeability resistance of 50,000 to 300,000 seconds and a moisture permeability of 2,000 to 4,000 g / m². 2Oil-resistant paper with a 24hr rating has been proposed. Patent document 1 aims to achieve recyclability without using fluorine-based compounds, and provides the desired oil-resistant paper by providing a water-soluble polymer layer as an oil-resistant layer on a substrate with high air permeability resistance obtained by highly beating natural fibers for papermaking to a water permeability of 85-90°SR. Patent Document 2 proposes an oil-resistant paper that is substantially free of fluororesins and has a Wangyan air permeability of 2,000 to 80,000 seconds, comprising a paper substrate, an intermediate layer containing polyvinyl alcohol, and a surface layer containing styrene-(meth)acrylic copolymer resin and a sizing agent. Patent Document 2 achieves an oil-resistant paper that is substantially free of fluorine compounds by providing an intermediate layer, which allows the surface layer to exhibit sufficient oil resistance even with a low adhesion amount. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 4520138 [Patent Document 2] Japanese Patent Publication No. 2022-85465 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The oil-resistant paper described in Patent Documents 1 and 2 is permeable to moisture. However, in some cases, heat-sealability is required for forming oil-resistant paper into packaging bags. The water-soluble polymer contained in the oil-resistant layer of the oil-resistant paper described in Patent Document 1 does not have heat-sealability. The styrene-(meth)acrylic copolymer resin used as an oil-resistant agent in the example of the oil-resistant paper described in Patent Document 2 has heat-sealability, but it cannot be said to have excellent heat-sealability, and lamination of a heat-seal layer is necessary to achieve practical heat-seal strength. However, when a heat-seal layer is laminated on the oil-resistant paper described in Patent Documents 1 and 2, the air permeability and moisture permeability are reduced by the heat-seal layer. The object of this invention is to provide a non-fluorine-based heat-sealable oil-resistant paper that has excellent oil resistance, breathability, and moisture permeability.

Means for Solving the Problem

[0007] The means for solving the problems of the present invention are as follows. 1. Oil-resistant paper impregnated with an oil-resistant paint containing a non-fluorine-based oil-resistant agent and a water-soluble polymer on a paper substrate, having a heat-seal layer on at least one surface of the oil-resistant paper, with an air permeability resistance (Wang研式) of 100 seconds or less and a moisture permeability of 1500 g / m 2 ·day or more, characterized by heat-seal oil-resistant paper. 2. The heat-seal oil-resistant paper according to 1., characterized in that the density is 0.8 g / cm 3 or less. 3. The heat-seal oil-resistant paper according to 1. or 2., characterized in that the smoothness (Wang研式) of the surface of the heat-seal layer is 50 seconds or less. 4. The heat-seal oil-resistant paper according to any one of 1. to 3., characterized in that the coating amount (dry weight) per side of the heat-seal layer is 2 g / m 2 or more.

Effects of the Invention

[0008] The heat-seal oil-resistant paper of the present invention does not use a fluororesin-based oil-resistant agent, so it can suppress adverse effects on health and the environment. The heat-seal oil-resistant paper of the present invention has excellent air permeability and moisture permeability while having heat-sealability. When wrapping warm food, moisture does not accumulate inside, so the crispy feeling of the food can be maintained, and it is particularly suitable for food packaging.

Modes for Carrying Out the Invention

[0009] "Heat-seal oil-resistant paper" The heat-seal oil-resistant paper of the present invention is oil-resistant paper impregnated with an oil-resistant paint containing a non-fluorine-based oil-resistant agent and a water-soluble polymer on a paper substrate, having a heat-seal layer on at least one surface of the oil-resistant paper, with an air permeability resistance (Wang研式) of 100 seconds or less and a moisture permeability of 1500 g / m2 It is more than a day old. Furthermore, whether or not the paint has been impregnated can be determined by observing the cross-section under a microscope or similar device.

[0010] ·Paper base material The paper substrate used in the present invention is not particularly limited, but it is preferable that it contains 30% by weight or more of hardwood pulp in which the ratio of lumen width (l) to fiber width (D) (l / D) is 0.50 or less on average, as this is suitable for forming oil-resistant paper with excellent breathability and moisture permeability. Hereinafter, in this specification, the ratio of lumen width (l) to fiber width (D) (l / D) will also be simply referred to as "l / D".

[0011] Hardwood pulp fibers have a lumen inside. l / D is a value that indicates the ratio of lumen width to fiber thickness; a smaller value indicates a smaller lumen and a thicker fiber wall. The l / D of pulp can be measured using the following procedure. 1. Dilute the pulp suspension to a concentration of 0.05%. 2. Using a dropping tube, drop the diluent onto a clean glass slide, and if necessary, use a dissecting needle to evenly disperse the fibers, then allow to dry. 3. Place three drops of C staining solution onto the dispersed fibers on the glass slide, place a coverslip on top to avoid air bubbles, remove any excess staining solution with blotting paper, and prepare the slide. 4. Observe the slide using an optical microscope, move the slide horizontally or vertically on a movable stage, measure the fiber width (D) and lumen width (l) at the center of the pulp in the longitudinal direction, and calculate l / D. When preparing paper stock, the l / D ratio of 100 or more pulps to be blended can be determined using the method described above, and the average value can be used as the pulp's l / D ratio. From the paper produced, the paper is disintegrated in the same manner as when preparing a slurry to measure the paper's disintegration and filtration efficiency. More than 200 pulps are identified using a dye solution that produces different colors depending on the tree species, and the l / D ratio is determined using the method described above. This allows for the determination of the amount of hardwood pulp blended and the pulp's l / D ratio.

[0012] (Hardwood pulp with an I / D ratio of 0.50 or less) Hardwood pulp with an l / D ratio of 0.50 or less forms a low-density sheet with thick, crush-resistant fiber walls. Although the degree varies depending on the wood species and other pulps used in the blend, by using a paper stock containing 30% by weight or more of hardwood pulp with an average ratio of lumen width (l) to fiber width (D) of 0.50 or less as the raw material, it becomes easy to obtain a low-density, i.e., a paper substrate with a sparse interior, even after the beating process necessary to obtain the paper strength required in the manufacturing process. Furthermore, because the interior of the paper substrate is sparse, oil-resistant coatings can be quickly impregnated into the entire paper substrate and adhered uniformly, thus reducing inconsistencies in the oil resistance performance of the resulting oil-resistant paper. Hardwood pulp with an l / D ratio of 0.50 or less preferably has an l / D ratio of 0.45 or less, and more preferably 0.40 or less.

[0013] There are no particular limitations on hardwood pulp with an l / D ratio of 0.50 or less, and examples include mechanical pulp (MP), thermomechanical pulp (TMP), sulfite pulp (SP), kraft pulp (KP), and their bleached pulp (BP) and unbleached pulp (UP). One or more of these can be used in mixtures. Among these, it is preferable to use kraft pulp (KP) which has excellent strength.

[0014] (Other pulp) Other pulps to be combined with hardwood pulp having an l / D of 0.50 or less may include, without particular limitation, hardwood pulp with an l / D of 0.50 or more, softwood pulp, regenerated cellulose, mercerized pulp, dissolved pulp and other refined pulps, bast fibers such as flax, kenaf, paper mulberry, and mitsumata, hard fibers such as bagasse, bamboo, and esparto, seed hair fibers such as cotton linters, and non-wood pulps such as Manila hemp and sisal hemp. The pulp constituting the paper base material may be beaten after mixing the hardwood pulp and other pulps, or it may be beaten separately and then mixed. The paper substrate of the present invention preferably contains 30% by weight or more, more preferably 40% by weight or more, even more preferably 50% by weight or more, and even more preferably 60% by weight or more, of the total pulp used as papermaking raw material, which is hardwood pulp with an l / D ratio of 0.50 or less.

[0015] The paper substrate of the present invention preferably has a Shopper Liegler filtration rate of 25°SR or more and 45°SR or less for the pulp constituting the paper substrate. Note that the pulp constituting the paper substrate refers to the total pulp contained in the paper substrate. Paper substrates with a Shopper Liegler filtration rate of less than 25°SR have low strength, so when impregnated with oil-resistant coatings, breakage of the paper substrate and deterioration of the paper substrate's structure become noticeable, which may result in uneven oil resistance performance. Furthermore, if the Shopper Liegler filtration rate exceeds 45°SR, uneven absorption of oil into the paper substrate occurs when impregnating with oil-resistant coatings, which may result in uneven oil resistance performance of the oil-resistant paper. The Shopper Liegler filtration rate is more preferably 27°SR or more and 40°SR or less, and even more preferably 27°SR or more and 35°SR or less.

[0016] (Other additives) Other additives may be added to the paper substrate as needed. Examples of additives include fillers, pigments, sizing agents, binders, fluorescent whitening agents, aluminum sulfate, yield enhancers, water drainage enhancers, dry strength enhancers, wet strength enhancers, coloring dyes, coloring pigments, and water-resistant agents, which can be used individually or in combination.

[0017] (Manufacturing method) Paper substrates can be manufactured using methods known to be used in papermaking applications. Specifically, they can be manufactured using long-wire paper machines, cylinder paper machines, short-wire paper machines, twin-wire paper machines, on-top hybrid paper machines, gap former machines, etc.

[0018] The basis weight of the paper substrate is 20 g / m². 2 It is preferable that the basis weight is 20 g / m² or more. 2If it is less than this, the tensile strength becomes weak, and the paper substrate may break during papermaking and oil-resistant layer processing. Also, in the case of a low basis weight substrate, uneven adhesion of the oil-resistant agent, which is considered to be affected by the state of pulp fibers, is likely to occur, and this causes unevenness in oil-resistant performance. The basis weight of the paper substrate is 30 g / m 2 or more is more preferable, and the upper limit is not particularly limited. For example, it can be 400 g / m 2 or less.

[0019] From the viewpoint of the permeability of the oil-resistant agent, the King研式 air permeability resistance of the paper substrate is preferably 100 seconds or less. The King研式 air permeability 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 King研式 air permeability 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 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 weight fluorine compound, and more preferably does not contain a fluorine-based compound.

[0021] (Non-fluorine-based oil-resistant agent) The non-fluorine-based oil-resistant agent can be used without particular limitation. For example, in the case of natural polymers, starch, cellulose derivatives, gelatin, casein, soy protein, etc., and in the case of synthetic polymers, polyvinyl alcohol, polyisoprene, polymers or copolymers of chloroprene, polydiene, polyalkene, 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, plant waxes, animal waxes, mineral waxes, petroleum waxes, etc. These compounds can be used alone or in combination of two or more. Among these, from the viewpoint of oil resistance, acrylic resins and fatty acid ester resins are preferable, and from the viewpoint of preventing oil penetration, acrylic resins are more preferable.

[0022] (Water-soluble polymer) Water-soluble polymers act as hydrophilic binders that fix non-fluorinated oil-resistant agents to the pulp fibers of paper substrates without hindering the performance of the oil-resistant agents. Examples of water-soluble polymers include carboxyalkylcellulose salts, alginates, pectates, polyacrylates, polymethacrylates, carboxyalkylated starch, phosphate-esterified starch, anionic modified polyvinyl alcohol resins, anionic polymer electrolyte salts such as anionic polyacrylamide, methylcellulose, hydroxyalkylcellulose, polyvinyl alcohol resins, polyvinylpyrrolidone, polyalkylene oxide, polyvinyl alkyl ethers, hydroxyalkylated starch, oxidized starch, pregelatinized starch and other polymer electrolytes, water-soluble polysaccharides such as guar gum, tranto gum, xanthan gum, acacia gum, carrageenan, galactomannan, pullulan, dextran, and dextrin, and water-soluble proteins such as gelatin and casein. These can be used individually or in combination of two or more. Among these, starch-based materials (carboxyalkylated starch, phosphate-esterified starch, hydroxyalkylated starch, oxidized starch, pregelatinized starch), acrylic resins, and polyvinyl alcohol-based resins are preferred from the viewpoint of processability, oil resistance, and material cost, with acrylic resins, which have excellent oil resistance, being even more preferred. Furthermore, the water-soluble polymer is preferably neutral in charge or has the same charge as the non-fluorinated oil repellent. However, when an aqueous solution of 10% by weight of the non-fluorinated oil repellent and 10% by weight of the water-soluble polymer is prepared, those that do not form a uniform aqueous phase (e.g., phase separation, aggregation, etc.) cannot be used.

[0023] Oil-resistant coatings preferably contain 5 to 100 parts by weight of a non-fluorine-based oil-resistant agent per 100 parts by weight of a water-soluble polymer, more preferably 10 parts by weight or more, even more preferably 15 parts by weight or more, even more preferably 70 parts by weight or less, and even more preferably 50 parts by weight or less, from the viewpoint of material cost. Oil-resistant coatings may contain additives such as surfactants, defoamers, surface sizing agents, paper strengthening agents, water-retaining agents, thickeners, release agents, and anti-slip agents, in addition to non-fluorine-based oil-resistant agents and water-soluble polymers, as long as they do not impair their performance.

[0024] For oil-resistant paper, it is preferable that the oil resistance of the impregnated surface is 2 or higher according to the kit value specified in J TAPPI No. 41:2000. If the oil resistance is less than a kit value of 2, oil from the food contained inside may seep out to the outside, staining the outer surface with oil. This kit value may be 3 or higher, 4 or higher, or 5 or higher. Here, the kit value is expressed as a number from 1 to 12, and a higher number means better oil resistance (oil barrier properties). Even with a low kit value, oil-resistant paper has excellent oil penetration prevention properties, making it difficult for oil to soak in and less prone to discoloration. The upper limit of the kit value for oil-resistant paper can be, for example, 7 or less, 6 or less, or 5 or less. To prevent paper tearing during papermaking, etc., the greaseproof paper preferably has a tensile strength 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, as measured in accordance with JIS P8113:2006.

[0025] (Impregnation method) The impregnation method for oil-resistant paint is not particularly limited, and known impregnation and coating methods can be used. Specifically, 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. can be appropriately selected and used. Among these, size press is preferred because it has excellent paint impregnation properties. Furthermore, the impregnation method can be either off-machine or on-machine, but on-machine is preferred from the viewpoint of productivity. Oil-resistant paints may be either water-based, using a solvent such as water, or solvent-based, using a solvent such as an organic solvent; however, water-based paints are preferred from a safety and health standpoint.

[0026] To obtain oil-resistant paper with a kit value of 2 or higher, the amount of oil-resistant paint applied should be 1.3 g / m² by dry weight. 2 The above is preferable, 1.4 g / m 2 The above is more preferable, 1.5 g / m 2The above is even more preferable. There is no particular upper limit on the amount of oil-resistant coating that can be applied, but for example, 10 g / m² by dry weight. 2 The following is preferable: The amount of oil-resistant paint applied is 10 g / m² by dry weight. 2 Beyond this point, oil resistance hardly improves any further, and the cost increases significantly. The amount of non-fluorinated oil repellent adhering to the surface varies depending on the proportion of the non-fluorinated oil repellent in the oil-resistant paint, but the amount of non-fluorinated oil repellent adhering to the surface is approximately 0.2 g / m² by dry weight. 2 Preferably, it should be 0.25 g / m 2 The above is more preferable, 0.3 g / m 2 The above is even more preferable, 0.35 g / m 2 The above is even more preferable, 0.4 g / m 2 The above is even more preferable, 0.45 g / m 2 The above is even more preferable. There is no particular upper limit on the amount of non-fluorine-based oil repellent applied, but for example, 5 g / m² by dry weight. 2 The following is preferable: The amount of non-fluorine-based oil repellent applied is 5 g / m² by dry weight. 2 Beyond this point, oil resistance hardly improves any further, and the cost increases significantly.

[0027] The oil-resistant paper preferably has a disintegration filtration rate of 250 ml CSF or more and 500 ml CSF or less. Disintegration filtration rate is the Canadian standard filtration rate measured in accordance with JIS P8121-2:2012 after disintegrating the oil-resistant paper using the method specified in JIS P8220-1:2012. A disintegration filtration rate of 300 ml CSF or more and 450 ml CSF or less is more preferable, and 350 ml CSF or more and 450 ml CSF or less is even more preferable.

[0028] "Heat-sealable oil-resistant paper" The heat-sealable oil-resistant paper of the present invention has a heat-seal layer on at least one surface of oil-resistant paper impregnated with the above-mentioned oil-resistant coating, and has an air permeability resistance (Wang-Ran method) of 100 seconds or less and a moisture permeability of 1500 g / m². 2• It must be more than a day. Furthermore, even if heat-sealable oil-resistant paper is obtained in the same manner except for using oil-resistant paper coated with the same oil-resistant paint, the above-mentioned air permeability resistance (Wang Ken method) must be 100 seconds or less, and the moisture permeability must be 1500 g / m². 2 Achieving a performance of more than one day is extremely difficult. This is because coating forms a uniform resin layer, making it difficult to achieve high breathability and moisture permeability.

[0029] In the heat-sealable oil-resistant paper of the present invention, the heat seal layer can be provided on both sides, but if it is provided on only one side, it is preferable to provide it on the processed surface impregnated with an oil-resistant coating. When applying the heat sealant to the oil-resistant paper, due to the relationship between the wettability of the heat sealant and the oil-resistant paper, it may not be possible to uniformly apply the heat seal layer in the case of high-kit oil-resistant paper. Therefore, when manufacturing heat-sealable oil-resistant paper, if the heat seal layer cannot be applied uniformly, it is necessary to adjust the viscosity and solvent composition of the heat sealant coating solution.

[0030] (Heat seal layer) The heat seal layer is formed by applying a coating containing a heat-sealable thermoplastic resin to at least one side of the oil-resistant paper. The thermoplastic resin included in the heat seal layer can be any known resin without particular limitation, such as polyethylene resins and polypropylene resins. Examples of polyethylene 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, and their derivatives, as well as mixtures thereof. Examples of polypropylene resins include polypropylene (PP) homopolymer, random polypropylene (random PP), block polypropylene (block PP), chlorinated polypropylene, carboxylic acid-modified polypropylene, and their derivatives, as well as mixtures thereof. Among these, those with a glass transition temperature of 100°C or lower are preferably used. The thermoplastic resin is preferably one with a glass transition temperature of -20°C to 85°C, and a melting point of 70°C to 140°C. Note that the glass transition temperature and melting point refer to the intermediate glass transition temperature and melting peak temperature, respectively, as measured in accordance with JIS P7121:2012. In addition to thermoplastic resin, the heat seal layer may also contain surfactants, waxes, inorganic pigments, dispersants, thickeners, etc., as needed.

[0031] The heat-sealable oil-resistant paper of the present invention has an air permeability resistance (Wang Ken method) of 100 seconds or less. From the viewpoint of breathability, the air permeability resistance (Wang Ken method) of the heat-sealable oil-resistant paper of the present invention is preferably 80 seconds or less, more preferably 60 seconds or less, even more preferably 40 seconds or less, and even more preferably 20 seconds or less. The heat-sealable oil-resistant paper of the present invention has a moisture permeability of 1500 g / m². 2• It is more than 2000 g / m². The heat-sealable oil-resistant paper of the present invention has a moisture permeability of 2000 g / m². 2 • Preferably 2500g / m² or more. 2 • More than 3000g / m² is preferable. 2 More preferably 3500g / m² or more. 2 • More than 4000g / m² is even more preferable. 2 • More than one day is even preferable. In the heat-sealable oil-resistant paper of the present invention, the smoothness (Oken method) of the surface of the heat-seal layer is preferably 50 seconds or less. From the viewpoint of heat-seal strength, this smoothness (Oken method) is more preferably 45 seconds or less, and even more preferably 40 seconds or less.

[0032] The method for coating the heat seal layer is not particularly limited and can be done using known coating equipment and coating systems. Examples of coating equipment 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 water-based coating using solvents such as water, and solvent-based coating using solvents such as organic solvents, but water-based coating is preferred due to its safety and low environmental impact.

[0033] The amount of coating applied to each side of the heat seal layer is not particularly limited as long as it provides sufficient heat seal strength, but generally, it is 1.6 g / m² by dry weight. 2 The above is preferable, 1.8 g / m 2 The above is more preferable, 2.0 g / m 2 The above is even more preferable. This coating amount is 1.6 g / m². 2 Below this amount, sufficient heat seal strength may not be obtained. While a higher coating amount per side of the heat seal layer tends to improve heat seal strength, too much increases drying energy costs and material costs. Therefore, a dry weight of 20g / m² is recommended. 2 The following is preferable: 10 g / m2 The following is more preferable: 5.0 g / m 2 The following is even more preferable: 4.0 g / m 2 The following is even more preferable. The heat seal layer may be a single layer or a multilayer structure of two or more layers. When the heat seal layer is a multilayer structure of two or more layers, it is preferable that the total coating amount of all coating layers be within the above range.

[0034] In the heat-sealable oil-resistant paper of the present invention, it is preferable that the heat-sealable surfaces are heat-bonded together and the substrate is destroyed when peeled off. The heat-sealable oil-resistant paper of the present invention preferably has a heat seal strength in the MD direction at 120°C of 0.5 N / 15 mm or more, more preferably 1.0 N / 15 mm or more, even more preferably 1.5 N / 15 mm or more, even more preferably 2.0 N / 15 mm or more, even more preferably 2.5 N / 15 mm or more, and even more preferably 3.0 N / 15 mm or more, and also preferably a heat seal strength in the CD direction at 120°C of 0.5 N / 15 mm or more, more preferably 1.0 N / 15 mm or more, even more preferably 1.5 N / 15 mm or more, even more preferably 2.0 N / 15 mm or more, and even more preferably 2.5 N / 15 mm or more. The heat-sealable oil-resistant paper of the present invention preferably has a heat seal strength in the MD direction at 160°C of 1.0 N / 15 mm or more, more preferably 1.5 N / 15 mm or more, even more preferably 2.0 N / 15 mm or more, even more preferably 2.5 N / 15 mm or more, and even more preferably 3.0 N / 15 mm or more, and a heat seal strength in the CD direction at 160°C of 0.5 N / 15 mm or more, more preferably 1.0 N / 15 mm or more, even more preferably 1.5 N / 15 mm or more, even more preferably 2.0 N / 15 mm or more, and even more preferably 2.5 N / 15 mm or more. [Examples]

[0035] Oil-resistant paper (Example 1) Softwood kraft pulp (NBKP) with an l / D ratio of 0.85 and hardwood kraft pulp (LBKP) with an l / D ratio of 0.34 were mixed at a ratio of 25% / 75% by weight and beaten using the Schöpper-Leighler method to achieve a filtration rate of 30°SR, which was then used as the raw material for papermaking. An oil-resistant coating with a solid content of 3.5% was prepared by mixing an acrylic resin (Unidyne XP-8001, 18% non-volatile content, Daikin Industries, Ltd.), which is a non-fluorine-based oil-resistant agent, with starch 1 (Penford Gum 290, nonionic hydroxyethylated starch, Incredion Corporation), which is a water-soluble polymer, at a solid content weight ratio of 30 parts by weight / 100 parts by weight. Papermaking raw materials with a dry basis weight of 40 g / m² 2 The paper was made using a target method, then impregnated with an oil-resistant coating using an on-machine size-press method, and finally dried using a calender to obtain oil-resistant paper. The adhesion rate of the oil-resistant paint is 2.0 g / m² by dry weight. 2 The amount of non-fluorine-based oil repellent applied is 0.5 g / m² by dry weight. 2 That was the case. A polyolefin resin (Zychsen AC, 30% non-volatile content, glass transition temperature 51°C, manufactured by Sumitomo Seika Co., Ltd.) was applied to the oil-resistant impregnation surface of the obtained oil-resistant paper by bar coating as a heat sealant to obtain heat-sealable oil-resistant paper. The application rate of the heat sealant is 3.3 g / m² by dry weight. 2 That was the case.

[0036] (Example 2) The application amount of the heat sealant is 2.0 g / m². 2 Except for the change made, heat-sealable oil-resistant paper was obtained in the same manner as in Example 1. (Comparative Example 1) A heat-sealable oil-resistant paper was obtained in the same manner as in Example 1, except that oil-resistant paper coated with an oil-resistant paint using a bar coating method instead of an impregnation method was used, and a heat-sealing agent was applied to the oil-resistant coated surface.

[0037] The obtained heat-sealable oil-resistant paper was evaluated as follows. The results are shown in Table 1. (Evaluation method) ·Basic weight The heat-sealable oil-resistant paper was measured in accordance with JIS P8124:2011. ·Paper thickness The heat-sealable oil-resistant paper was measured in accordance with JIS P8118:1998. ·density The heat-sealable oil-resistant paper was calculated from the measured basis weight and paper thickness.

[0038] ·Smoothness (Oken style) The heat-sealable oil-resistant paper, both coated and uncoated, was measured using a water column type air permeability and smoothness tester (manufactured by Asahi Seiko Co., Ltd.) in accordance with JIS P8155:2010. ·Air permeability resistance (Ouken style) For heat-sealable oil-resistant paper, the average value of four measurements was calculated in accordance with the Oguri-type testing machine method described in JIS P8117 (2009) for air permeability and air permeability resistance, and this was defined as air permeability resistance (Oguri-type) (seconds). The measurement range for air permeability resistance using the water column type Oguri-type air permeability and smoothness tester (KY5 model, manufactured by Asahi Seiko Co., Ltd.) is 0 to 5,000 seconds.

[0039] • Tensile strength The heat-sealable oil-resistant paper was measured in accordance with JIS P8113:2006. ·Moisture permeability The heat-sealable oil-resistant paper was measured in accordance with JIS Z0208:1976 "Test method for moisture permeability of moisture-proof packaging materials (cup method)" under condition B (temperature 40±0.5℃, relative humidity 90%±2%). For the measurement, the weight after being placed in an environmental testing machine for 16 hours was used as the initial value, and the weight was measured again after 2 hours. The change in weight was converted to a 24-hour value and used as the moisture permeability value.

[0040] • Water absorption (Cobb method) The coated surface of the heat-sealable oil-resistant paper was measured at 23°C with a contact time of 60 seconds, in accordance with JIS P8140:1998. • Rapeseed oil test One drop of rapeseed oil (Wako Grade 1, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was placed on each side of the heat-sealable oil-resistant paper. After 1, 3, 7, and 24 hours, the oil was wiped off with a tissue and visually inspected and evaluated according to the following criteria. (Evaluation Criteria) ○: No stains. △: Stain present, but no bleed-through on the other side. ×: Stain present, with bleed-through to the other side, or the stain is more extensive than an oil droplet, but there is no bleed-through to the other side.

[0041] • Heat seal strength The test was conducted in accordance with JIS Z1707:2019 7.4 "Heat seal strength test". Two 100mm square test pieces were cut from the obtained heat-sealable oil-resistant paper, and the coated layers were brought into contact with each other. Using a heat seal tester (Tester Industries Co., Ltd., TP-7018, seal width 10mm), the pieces were heat-sealed at pressurized temperatures of 120°C and 160°C, with a pressurized pressure of 98kPa and a pressurized time of 1.0 second. Measurement samples were then cut from the heat-sealed 100mm square test pieces so that the long side was 100mm and the short side was 15mm. The sample was left at 23°C and 50% RH for 10 minutes. Under this atmosphere, the long end of the sample was clamped in the upper and lower fixtures of a Tensilon universal tester (A&D Co., Ltd., RTG-1210), and the peel strength, i.e., the HS strength (N / 15mm), was measured while peeling the sample from the long end side at a speed of 300 mm / min (T-type). Heat seal strength was measured under two conditions: when the longer side was oriented in the MD (paper direction) and when the longer side was oriented in the CD (paper width) direction.

[0042] [Table 1]

[0043] ·result The non-fluorine-based heat-sealable oil-resistant paper obtained in Examples 1 and 2 has sufficient oil resistance on both sides, an air permeability resistance (Wangyan method) of 100 seconds or less, and a moisture permeability of 1500 g / m². 2It was more than 1 day old and also had excellent breathability and moisture permeability. In contrast, the non-fluorine-based heat-sealable oil-resistant paper obtained in Comparative Example 1 had inferior oil resistance, and its air permeability resistance (Wang Ken method) was 115 seconds, while its moisture permeability was 1400 g / m². 2 It was a day-use material, and also lacked breathability and moisture permeability.

Claims

1. Oil-resistant paper in which an oil-resistant coating containing a non-fluorine-based oil-resistant agent and a water-soluble polymer is impregnated into a paper substrate, The oil-resistant paper has a heat-seal layer on at least one surface, Air permeability resistance (Wang Ren method) of 100 seconds or less, and moisture permeability of 1500 g / m². ２ Heat-sealable oil-resistant paper characterized by having a lifespan of 2 days or more.

2. Density is 0.8 g / cm³ ３ The heat-sealable oil-resistant paper according to claim 1, characterized in that it is as follows:

3. The heat-sealable oil-resistant paper according to claim 1 or 2, characterized in that the smoothness (Oken method) of the surface of the heat-seal layer is 50 seconds or less.

4. The coating amount (dry weight) per side of the heat seal layer is 2 g / m². ２ The heat-sealable oil-resistant paper according to claim 1 or 2, characterized in that it is as described above.

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