Greaseproof paper and method for producing the same

Abstract

An object of the present disclosure is to provide an oil-resistant paper that has oil resistance such that cooking oil such as salad oil hardly penetrates even in an environment at 50 °C and air permeability such that water vapor generated from packaged contents can moderately pass through, has transparency such that the contents can be visually recognized, uses a non-fluorine-based resin having few environmental problems as an oil-resistant agent, and generates little odor in a high-temperature environment, and a method for producing the same.SOLUTION: The oil-resistant paper according to the present invention is oil-resistant paper in which a paper base material mainly composed of pulp contains an oil-resistant agent, wherein the oil-resistant agent contains a fatty ester, the content of the fatty ester in the oil-resistant paper is 7% by mass or more and 30% by mass or less, and the air permeability of the oil-resistant paper measured in accordance with JISP8117:2009 Air Permeability and Air Permeability Testing Method, Oken Type Testing Method is 150 seconds or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to greaseproof paper and a method for producing the same. [Background technology]

[0002] Greaseproof paper is widely used as wrapping paper, packaging containers, paper bases for food trays, etc. for cooked foods that contain a lot of oil and moisture, such as fast food, fried foods, and baked foods, as well as foods that contain a lot of fat and oil, such as chocolate, and as a paper base material for oxygen absorbers.

[0003] Greaseproof paper, especially thin greaseproof paper, tends to be required to be breathable in addition to oil resistance. For example, packaging paper for hamburgers and hot snacks requires both oil resistance to prevent the passage of grease and breathability to allow water vapor to pass through.

[0004] In order to provide oil resistance while also achieving breathability, oil-resistant agents containing fluororesin have traditionally been used. For example, greaseproof paper, in which the surface of paper or paperboard is coated with an oil-resistant agent containing fluororesin, and greaseproof paper containing fluororesin between the paper layers (in the paper layers), are known. However, greaseproof paper containing fluororesin may generate organic fluorine compounds when subjected to high-temperature treatment such as cooking or when incinerated. Among these organic fluorine compounds, perfluorooctanesulfonic acid and perfluorooctanoic acid are persistent and highly bioaccumulative, and therefore are widely present in environmental waters and wildlife, raising concerns about their adverse effects on health and the environment.

[0005] To solve these problems, greaseproof paper using non-fluorine-based resins has been proposed (see, for example, Patent Documents 1 to 4). For example, Patent Document 1 proposes that at least one coating layer containing starch and / or polyvinyl alcohol and a fatty acid is applied to at least one side of a substrate in an amount of 0.5 to 20 g / m. 2Patent Document 2 discloses an oil-resistant sheet-like material characterized by having an oil-resistant agent layer formed on at least one side of a paper support, the oil-resistant agent layer containing starch and wax containing hydrophobic groups, and the oil-resistant paper having an Oken air permeability of 2000 seconds or less measured in accordance with JAPAN TAPPI Paper Pulp Testing Method No. 5-2:2000. Patent Document 3 discloses a paper base paper mainly made of natural fibers for papermaking, in which an emulsion coating liquid of an acrylic resin having a glass transition temperature (Tg) of 10 to 28°C is applied in an amount of 3 to 20 g / m2 in terms of solids to one or both sides of the base paper. 2 Patent Document 4 discloses a recyclable waterproof and oil-resistant paper with good blocking resistance, which is obtained by coating and heat-drying.Patent Document 4 discloses a fiber structure (Ts1) having a planar fiber structure substrate (T), characterized in that it is provided with a polyester resin layer (R1) formed by coating one or both sides of the fiber structure substrate with a paint containing a polyester resin with a paint solids content in the range of 10% to 60%.

[0006] Furthermore, grease-resistant paper with high breathability and oil resistance has been proposed (see, for example, Patent Document 5). Patent Document 5 discloses paper having a coating layer containing a water-based emulsion oil-resistant coating agent containing component (a) which is hydrogenated castor oil and / or rice wax, component (b) which is polyvinyl alcohol and / or casein, and water. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-219786 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-237941 [Patent Document 3] Japanese Patent Application Publication No. 9-111693 [Patent Document 4] WO2004 / 083521 publication [Patent Document 5] WO2023 / 153195 publication Summary of the Invention [Problem to be solved by the invention]

[0008] However, the greaseproof papers of Patent Document 1 and Patent Document 2 contain auxiliary agents such as fatty acids and waxes to form an oil-resistant layer, which results in a problem of reduced oil resistance when exposed to relatively high-temperature oils such as 50°C. Furthermore, the waterproof and greaseproof paper of Patent Document 3 and the greaseproof paper of Patent Document 4 both have improved film properties to achieve oil resistance, which tends to impair breathability. While it is important for greaseproof paper to have both oil resistance and breathability, the greaseproof papers of Patent Documents 1 to 4 do not necessarily achieve both. Furthermore, some resins may generate odors, which may impair the flavor when used as food packaging.

[0009] Furthermore, for example, when displaying packaged products in stores, consumers have been demanding the ability to see the contents of the package, as with a transparent plastic tray, when selecting a product. However, greaseproof paper is generally opaque, and the packaged contents are not visible. Therefore, transparent plastic packaging materials have been adopted for applications where the contents are visible. In recent years, there has been a demand for reducing disposable plastic products, and a movement to replace plastic with paper has been promoted. Patent Documents 1 to 5 do not mention the transparency of greaseproof paper at all, and no greaseproof paper that combines oil resistance and breathability with transparency has been proposed to date.

[0010] The present disclosure has been made in consideration of these problems, and aims to provide oil-resistant paper and a method for manufacturing the same that has oil resistance that makes it difficult for edible oils such as salad oil to penetrate even in an environment of 50°C, and breathability that allows water vapor generated from packaged contents to pass through at a moderate level, while also having transparency that allows the contents to be seen, and that uses a non-fluorine-based resin that is environmentally friendly as an oil-resistant agent and generates little odor in high-temperature environments. [Means for solving the problem]

[0011] The grease-resistant paper of the present invention is characterized in that a paper base material mainly made of pulp contains an grease-resistant agent, the grease-resistant agent includes a fatty acid ester, the content of the fatty acid ester in the grease-resistant paper is 7% by mass or more and 30% by mass or less, and the air permeability of the grease-resistant paper measured in accordance with JIS P 8117:2009 Air permeability and low air permeability altitude test method, Oken test method, is 150 seconds or less.

[0012] In the greaseproof paper according to the present invention, the opacity of the greaseproof paper is preferably 55% or less, which can further improve the visibility of the contents.

[0013] In the greaseproof paper according to the present invention, the fatty acid ester preferably has a melting point of 75° C. or higher, so that high grease resistance can be maintained even when high-temperature contents are packaged.

[0014] In the greaseproof paper according to the present invention, the basis weight of the greaseproof paper is 35 g / m 2 More than 80g / m 2 It is preferable that the following conditions are satisfied: Transparency can be further improved.

[0015] The greaseproof paper according to the present invention includes an embodiment in which the water repellency of the greaseproof paper measured in accordance with JAPAN TAPPI No. 68 water repellency test method is R8 or more.

[0016] The greaseproof paper according to the present invention includes a form in which the kit oil resistance of the greaseproof paper measured in accordance with JAPAN TAPPI No. 41 Oil Repellency Testing Method Kit Method is 3 or more.

[0017] In the greaseproof paper according to the present invention, the paper base preferably does not contain a sizing agent or the sizing agent content of the paper base is preferably 10 mass ppm or less, which makes it easier to impregnate the paper base with the greaseproofing agent, thereby achieving high breathability and high transparency while improving oil resistance.

[0018] In the greaseproof paper according to the present invention, when the surface of the greaseproof paper is observed under an electron microscope at a magnification of 150 to 500 times, the greaseproof agent film is preferably observed, and the greaseproof agent film preferably has pores or depressions, thereby achieving high breathability while improving oil resistance.

[0019] In the greaseproof paper according to the present invention, the greaseproofing agent is preferably distributed throughout the thickness of the paper base material, thereby achieving high breathability and high transparency while improving oil resistance.

[0020] In the greaseproof paper according to the present invention, when the surface of the greaseproof paper is observed under an electron microscope at a magnification of 150 to 500 times, the greaseproof paper preferably has some spaces between the pulp particles filled with the oil-proofing agent and some spaces between the pulp particles not filled with the oil-proofing agent, thereby achieving high breathability and high transparency while improving oil resistance.

[0021] The method for producing grease-resistant paper according to the present invention is a method for producing grease-resistant paper in which a paper base material mainly made of pulp contains an oil-resistant agent, and comprises a papermaking process for producing the paper base material, and an oil-resistant agent application process for impregnating the paper base material with a coating liquid containing a fatty acid ester as the oil-resistant agent, wherein the content of the oil-resistant agent in the grease-resistant paper in the oil-resistant agent application process is 7% by mass or more and 30% by mass or less, and the air permeability of the grease-resistant paper is 150 seconds or less.

[0022] In the method for producing greaseproof paper according to the present invention, the papermaking step preferably includes a step of adjusting the air permeability of the paper base material to 25 seconds or less, thereby further improving the breathability of the greaseproof paper.

[0023] In the method for producing greaseproof paper according to the present invention, the sizing degree of the paper base material is preferably 0 to 5 seconds, which makes it easier to impregnate the paper base material with an oil-proofing agent, thereby achieving high breathability and high transparency while improving oil resistance.

[0024] In the method for producing greaseproof paper according to the present invention, the basis weight of the paper base material is 20 to 45 g / m2 It is preferable that the above formula is satisfied. High breathability and high transparency can be achieved at the same time.

[0025] In the method for producing greaseproof paper according to the present invention, the air permeability of the paper base material is preferably 10 seconds or less, which can further improve the breathability. [Effects of the Invention]

[0026] According to the present disclosure, it is possible to provide oil-resistant paper and a method for manufacturing the same that combine oil resistance and breathability while being transparent enough to allow the contents to be seen, uses a non-fluorine-based resin as an oil-resistant agent that poses few environmental problems, and produces little odor in high-temperature environments. [Brief explanation of the drawings]

[0027] [Figure 1] This shows a secondary electron image of the surface of greaseproof paper or the surface of a paper substrate taken with an electron microscope at 150x magnification. [Figure 2] This shows a secondary electron image of the surface of greaseproof paper or the surface of a paper substrate taken with an electron microscope at 500x magnification. [Figure 3] The SEM-EDS observation results of a cross section of greaseproof paper are shown, where (a1) and (a2) are secondary electron images, (b1) and (b2) are elemental mapping images of carbon and oxygen, and (c1) and (c2) are elemental mapping images of carbon. [Figure 4] The SEM-EDS observation results of the cross section of the paper substrate are shown, where (a1) and (a2) are secondary electron images, (b1) and (b2) are elemental mapping images of carbon and oxygen, and (c1) and (c2) are elemental mapping images of carbon. DETAILED DESCRIPTION OF THE INVENTION

[0028] Next, the present invention will be described in detail with reference to the embodiments, but the present invention is not limited to these descriptions. Various modifications of the embodiments may be made as long as the effects of the present invention are achieved.

[0029] The grease-resistant paper according to this embodiment is grease-resistant paper in which a paper base material mainly made of pulp contains an grease-resistant agent, the grease-resistant agent including a fatty acid ester, the fatty acid ester content of the grease-resistant paper being 7% by mass or more and 30% by mass or less, and the air permeability of the grease-resistant paper measured in accordance with JIS P 8117:2009, Air Permeability and Low Air Permeability Height Test Method, Oken Test Method, is 150 seconds or less.

[0030] The greaseproof paper of this embodiment has an greaseproofing layer containing an greaseproofing agent formed on at least one surface of a paper substrate. The paper substrate is not particularly limited and can be appropriately selected depending on the application, and examples include bleached or unbleached kraft paper (acid paper or neutral paper), fine paper, medium-quality paper, liner, one-side glazed paper, etc.

[0031] Examples of pulp constituting the paper base material include wood pulp, non-wood pulp, recycled paper pulp, and synthetic fiber pulp. Examples of wood pulp include chemical pulp and mechanical pulp made from softwood or hardwood. Examples of non-wood pulp include kenaf pulp, bagasse pulp, rag pulp, linen pulp, hemp pulp, paper mulberry pulp, mitsumata pulp, gampi pulp, straw pulp, and bamboo pulp. Examples of recycled paper include magazine waste paper, flyer waste paper, colored recycled paper, newspaper waste paper, Kent recycled paper, white recycled paper, coated recycled paper, copying recycled paper, and broke recycled paper.

[0032] Among these, it is preferable to contain chemical pulp such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood bleached sulfite pulp (LBSP), softwood bleached sulfite pulp (NBSP), etc. This allows for the production of white, clean-looking greaseproof paper for food packaging.

[0033] The pulp is beaten to a freeness of 250 to 550 ml, preferably 300 to 450 ml, according to the Canadian Standard Freeness Test Method specified in JIS P8121-1995. The degree of beating is adjusted appropriately to adjust the breathability of the paper base material. If the freeness is less than 250 ml, the air permeability for greaseproof paper may become too high, potentially impairing breathability. On the other hand, if the freeness is more than 550 ml, the entanglement of the fibers may weaken, potentially reducing strengths such as tensile strength.

[0034] In the paper base material, "mainly made of pulp" means that the pulp content relative to the total mass of the paper base material is 70% by mass or more, and preferably 90% by mass or more.

[0035] The paper base material may contain general-purpose additives, such as sizing agents (alkyl ketene dimers, alkenyl succinic anhydrides, higher fatty acids, petroleum resins, rosin, etc.), paper strength agents (starch, polyacrylamide, polyamidoamine epichlorohydrin, etc.), retention aids, drainage aids, aluminum sulfate, pH adjusters, antifoaming agents, pitch control agents, slime control agents, etc., selected as needed and used within the scope that does not impair the effects of the invention.

[0036] In the greaseproof paper according to this embodiment, the paper substrate preferably does not contain a sizing agent, or the sizing agent content of the paper substrate is preferably 10 mass ppm or less. This makes it easier to impregnate the paper substrate with the greaseproof agent, thereby improving oil resistance while achieving both high breathability and high transparency. The method for measuring the sizing agent content is not particularly limited, but for example, it is a method in which a greaseproof paper having a predetermined area is immersed in methyl ethyl ketone (MEK), extracted with MEK, and measured with a GC-MS (gas chromatograph mass spectrometer) to quantify the sizing agent peak area.

[0037] The oil-proofing agent preferably contains a fatty acid ester as an active ingredient. Here, the term "active ingredient" refers to a component that is blended to provide oil resistance among the components constituting the oil-proofing agent. The fatty acid ester is, for example, an ester of an alcohol and a fatty acid. Examples of the alcohol include mono- to hexavalent alcohols (e.g., aliphatic alcohols) having 1 to 50 carbon atoms, and examples of the fatty acid include saturated or unsaturated fatty acids having 2 to 50 carbon atoms, particularly 5 to 30 carbon atoms. Examples of the fatty acid ester include ethylene glycol fatty acid esters, propylene glycol fatty acid esters, glycerin mono-fatty acid esters, diglycerin fatty acid esters, polyglycerin fatty acid esters, organic acid monoglycerides, sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyalkylene fatty acid esters, polyoxyalkylene glycerin fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene hydrogenated castor oil, polyoxyalkylene castor oil, polyoxyalkylene hydrogenated castor oil fatty acid esters, castor oil fatty acid esters, and hydrogenated castor oil fatty acid esters, but are not limited to these. The oil-proofing agent may contain only one type of fatty acid ester or two or more types of fatty acid ester, but is not limited to this.

[0038] The refractive index of the oil-proofing agent is preferably 1.40 to 1.60, and more preferably 1.45 to 1.55. By setting the refractive index within this range, diffuse reflection can be suppressed, further increasing transparency. Furthermore, since the refractive index of cellulose fibers is generally said to be in the range of 1.4 to 1.6, if the refractive index of the oil-proofing agent is within this range, the difference between the refractive index of the oil-proofing agent and that of the cellulose fibers becomes small, making it easier to improve transparency and visibility. The refractive index can be measured, for example, according to JIS K 7142:2014 "Plastics - Determination of refractive index."

[0039] A single oil-proofing agent may be used, or two or more may be used in combination. When two or more types are used in combination, for example, oil-proofing agents containing different types of fatty acid esters may be used in combination, or an oil-proofing agent containing a fatty acid ester as an active ingredient may be used in combination with an oil-proofing agent that does not contain a fatty acid ester as an active ingredient. When an oil-proofing agent that does not contain a fatty acid ester as an active ingredient is used, it is preferable that the greaseproof paper does not contain an oil-proofing agent that exhibits oil resistance by forming a film, such as styrene-acrylic resin, polyvinyl alcohol, starch, or styrene-butadiene latex copolymer. Such film-type oil-proofing agents coat the surface of the paper substrate, which may reduce breathability. It is also preferable that the greaseproof paper does not contain wax-based oil-proofing agents such as microcrystalline wax or paraffin wax. Wax-based oil-proofing agents do not form a film, but they may reduce oil resistance to high-temperature oils, such as those at 50°C.

[0040] In the grease-resistant paper according to this embodiment, the melting point of the fatty acid ester is preferably 75°C or higher, and more preferably 85°C or higher. If the melting point of the fatty acid ester is lower than 75°C, the oil resistance may be reduced when high-temperature contents are packaged. There are no particular restrictions on the upper limit of the melting point of the fatty acid ester, but in order to prevent the drying temperature required to melt the grease-resistant agent and penetrate it into the paper from becoming too high, it is preferably 120°C or lower, and more preferably 100°C or lower.

[0041] The content of fatty acid esters in greaseproof paper is 7% by mass or more and 30% by mass or less, preferably 14% by mass or more and 30% by mass or less, and more preferably 20% by mass or more and 30% by mass or less. If the content of fatty acid esters in greaseproof paper is less than 7% by mass, the oil resistance and transparency will be insufficient. If the content of fatty acid esters in greaseproof paper is more than 30% by mass, the breathability will be insufficient. Fatty acid esters in greaseproof paper include (1) fatty acid esters blended as active ingredients in oilproofing agents, (2) fatty acid esters blended as dispersants, and (3) fatty acid esters blended in small amounts as additives in oilproofing agents whose active ingredients are components other than fatty acid esters, and the content of fatty acid esters in greaseproof paper is calculated based on the ratio of the total content of these. The content of fatty acid esters in greaseproof paper can be calculated using the following formula 1. (Equation 1) Fatty acid ester content in greaseproof paper [mass%] = {Fatty acid ester solid content per unit area [g / m 2 ] / (paper substrate basis weight [g / m 2 ] + fatty acid ester solid content per unit area [g / m 2 ])}×100 Here, the method for measuring the content of fatty acid esters per unit area in terms of solid content is not particularly limited, but for example, a method is used in which greaseproof paper having a predetermined area is immersed in isopropyl alcohol (IPA), the fatty acid esters are extracted with IPA, and the fatty acid esters are measured using a GC-MS (gas chromatograph mass spectrometer) to quantify them from the peak area of ​​the fatty acid esters.

[0042] The air permeability of the greaseproof paper measured according to the Oken test method (JIS P 8117:2009, Air Permeability and Air Permeability Resistance Test Method) is 150 seconds or less, preferably 120 seconds or less, and more preferably 100 seconds or less. The smaller the air permeability value, the higher the air permeability, and the higher the air permeability value, the lower the air permeability. By achieving an Oken air permeability of 150 seconds or less, water vapor generated from the contents, such as hot snacks stored in a 50°C warm environment or steam from freshly fried foods, can pass through the greaseproof paper, preventing water droplets from forming inside the greaseproof paper and maintaining the crispiness of the contents. The lower limit of the Oken air permeability is not particularly limited, but from the viewpoint of strength, it is preferably 10 seconds or more, more preferably 15 seconds or more.

[0043] In the greaseproof paper according to this embodiment, the opacity of the greaseproof paper is preferably 55% or less, and more preferably 50% or less. If the opacity exceeds 55%, the transparency may be insufficient, and the visibility of the contents may be poor. The opacity is a value measured in accordance with JIS P 8149:2000 "Opacity test method (paper backing) - diffusion proof method," and the smaller the opacity value, the higher the transparency.

[0044] The greaseproof paper according to this embodiment has a basis weight of 35 g / m 2 More than 80g / m 2 Preferably, it is 40 g / m or less. 2 More than 60g / m 2 It is more preferable that the basis weight of the greaseproof paper is 35 g / m or less. 2 If the paper is less than 80g / m², it may not be strong enough for some applications. 2 If the thickness exceeds this, the transparency may be insufficient and the visibility of the contents may be poor.

[0045] The greaseproof paper according to this embodiment includes those in which the water repellency of the greaseproof paper measured in accordance with JAPAN TAPPI No. 68 Water Repellency Testing Method is R8 or higher. Such water repellency can be achieved by the inclusion of a fatty acid ester in the greaseproof paper. This makes the greaseproof paper less susceptible to wetting, so that when used as food packaging, even if steam from hot snacks or the like turns into water droplets, they are less likely to penetrate the greaseproof paper itself, thereby preventing a decrease in strength. The water repellency of the greaseproof paper is more preferably R9 or higher, and even more preferably R10.

[0046] The greaseproof paper according to this embodiment includes those in which the kit oil resistance of the greaseproof paper measured in accordance with JAPAN TAPPI No. 41 Oil Repellency Test Kit Method is 3 or higher. The kit oil resistance of the greaseproof paper is more preferably 4 or higher, and even more preferably 5 or higher. Such oil resistance can be achieved by ensuring that the fatty acid ester content in the greaseproof paper is equal to or higher than the above-mentioned predetermined ratio.

[0047] The greaseproof paper according to this embodiment preferably has oil resistance to oil at 50° C. The oil resistance to oil at 50° C. can be evaluated, for example, by the method described in the examples.

[0048] In the greaseproof paper according to this embodiment, when the surface of the greaseproof paper is observed using an electron microscope at a magnification of 150 to 500 times, an greaseproofing agent film is observed, and the greaseproofing agent film preferably has pores or depressions. This allows for high breathability while improving oil resistance. A pore refers to a bottomless, cylindrical through-hole extending through the thickness of the greaseproof paper, while a depression refers to a bottomed recess filled with the greaseproofing agent. The pores or depressions preferably have a diameter of 100 nm or more, and do not include so-called pinholes caused by air bubbles or the like, which have a diameter of less than 100 nm.

[0049] The oil-proofing agent film is preferably a discontinuous film formed along the irregularities of the pulp fibers that make up the surface of the paper substrate. A film formed along the irregularities of the pulp fibers that make up the surface of the paper substrate refers to a film in which the outlines of the pulp fibers that make up the surface of the paper substrate can be clearly seen in an electron microscope image observed at the above magnification. For example, a film of a film-type oil-proofing agent such as SBR is a continuous film without holes or depressions in an electron microscope image, and although the irregularities of the pulp fibers that make up the surface of the paper substrate can be seen to some extent, the outlines of the pulp fibers are blurred.

[0050] In the greaseproof paper according to the present embodiment, when the surface of the greaseproof paper is observed at a magnification of 150 to 500 times using an electron microscope, the greaseproof paper preferably has some areas where the gaps between the pulp particles are filled with an oilproofing agent and some areas where the gaps between the pulp particles are not filled with the oilproofing agent. It is possible to achieve both high breathability and high transparency while improving oil resistance. The reason why high breathability and high transparency can be achieved at the same time is unclear, but the paper base material has voids between the pulp particles, and air is present in these voids. Since the difference between the refractive index of the pulp and that of the oilproofing agent is large, the opacity of the paper base material increases and it generally appears white. Since the difference between the refractive index of the pulp and that of the oilproofing agent is smaller than the difference between the refractive index of the pulp and that of the air, when the gaps between the pulp particles in the paper base material are filled with the oilproofing agent, the opacity decreases. Therefore, it is presumed that the more voids between the pulp particles in the paper base material are filled with the oilproofing agent, the lower the opacity tends to be. On the other hand, a paper base has low air permeability because air passes through the gaps between the pulp particles. Therefore, it is presumed that the more gaps between the pulp particles in the paper base that are not filled with an oil-proofing agent, the lower the air permeability tends to be. In the greaseproof paper according to this embodiment, by setting the content of the oil-proofing agent contained in the greaseproofing paper within a predetermined range, the gaps between the pulp particles are appropriately divided into gaps filled with the oil-proofing agent and gaps not filled with the oil-proofing agent, thereby ensuring low air permeability while reducing opacity. "Pulp particles filled with the oil-proofing agent" refers to a state in which, in an image of the surface of the greaseproofing paper observed with an electron microscope, a film of the oil-proofing agent is spread over the openings formed by the intersections of the pulp fibers. The gaps between the pulp particles filled with the oil-proofing agent include a state in which a film of the oil-proofing agent is spread over the entire openings formed by the intersections of the pulp fibers, completely blocking the openings, and a state in which a film of the oil-proofing agent is spread over a portion of the opening, partially blocking the openings. On the other hand, the areas where the gaps between the pulp fibers are not filled with oil-resistant agent include a form in which the entire opening formed by the intersection of the pulp fibers is open, and a form in which a film of oil-resistant agent is applied to part of the opening, causing the opening to be partially open.

[0051] In the greaseproof paper according to this embodiment, the greaseproofing agent is preferably distributed throughout the thickness of the paper substrate. This allows for enhanced oil resistance while simultaneously achieving high breathability and transparency. The distribution of the greaseproofing agent can be confirmed by visualizing the elemental distribution in an image of the cross section of the greaseproof paper, magnified at a magnification ranging from 500 to 700 times using an energy dispersive X-ray analyzer (SEM-EDS) attached to a scanning electron microscope, and then examining the distribution of carbon derived from the greaseproofing agent. The following methods can be used to distinguish between carbon derived from the greaseproofing agent and carbon derived from the paper substrate. For cellulose in the paper substrate, the oxygen distribution and carbon distribution generally coincide. On the other hand, fatty acid ester-based greaseproofing agents have a stronger carbon reactivity than oxygen. Therefore, by superimposing the carbon distribution and oxygen distribution and displaying them, carbon distribution areas that do not overlap with the oxygen distribution can be identified as carbon derived from the greaseproofing agent.

[0052] The greaseproof paper according to this embodiment preferably does not have an greaseproofing agent coating on the surface of the paper substrate. The presence or absence of a coating can be confirmed, for example, by observing the cross section of the greaseproof paper at a magnification of 500 to 700 times using an energy dispersive X-ray analyzer (SEM-EDS) attached to a scanning electron microscope.

[0053] In the greaseproof paper according to this embodiment, the pulp is preferably coated with the oil-resistant agent, and more preferably adhered to the entire outer surface of each pulp fiber, thereby enabling the paper to exhibit high oil resistance not only on the surface but also on the edge.

[0054] The method for producing grease-resistant paper according to this embodiment is a method for producing grease-resistant paper in which a paper base material mainly made of pulp contains an oil-resistant agent, and includes a papermaking process for producing the paper base material, and an oil-resistant agent application process for impregnating the paper base material with a coating liquid containing a fatty acid ester as an oil-resistant agent, wherein the content of the oil-resistant agent in the grease-resistant paper in the oil-resistant agent application process is 7% by mass or more and 30% by mass or less, and the air permeability of the grease-resistant paper is 150 seconds or less.

[0055] The papermaking process includes a dispersing step in which pulp is dispersed in water to form a pulp slurry, a beating step in which the pulp slurry is adjusted to a predetermined freeness using a beater, and a papermaking step in which the pulp slurry is made into paper using a papermaking machine. The pulp slurry may contain only one type of pulp selected from the above-mentioned pulps, or two or more types in combination. In addition to the pulp, the pulp slurry may also contain general-purpose additives.

[0056] The paper base material may be produced using a paper machine such as a Fourdrinier paper machine, a short wire paper machine, a cylinder paper machine, a Yankee paper machine, an on-top former, a combination former, a separate former, or a gap former, but is not limited to these, and the paper may be produced in a single layer or a multilayer.

[0057] In the method for producing grease-resistant paper according to this embodiment, the papermaking process preferably includes a step of adjusting the air permeability of the paper base material to 50 seconds or less. This can further improve the breathability of the grease-resistant paper. Furthermore, since the oil-proofing agent is more likely to penetrate the entire thickness of the paper base material, oil resistance and transparency can be more efficiently improved. In the method for producing grease-resistant paper according to this embodiment, the air permeability of the paper base material is preferably 30 seconds or less, more preferably 25 seconds or less, and even more preferably 10 seconds or less. The lower limit of the air permeability of the paper base material is not particularly limited, but from the viewpoint of strength, it is preferably 5 seconds or more, more preferably 8 seconds or more. Methods for adjusting the air permeability of the paper base material include, for example, adjusting the basis weight of the paper base material, adjusting the freeness of the pulp slurry, or adjusting the blending ratio of pulp. The papermaking process preferably includes a step of beating the pulp to a freeness of 300 ml or more. The freeness of the pulp is more preferably 350 ml or more. In the papermaking process, the pulp slurry preferably contains 20% by mass or more of softwood pulp such as bleached softwood kraft pulp (NBKP) or bleached softwood sulfite pulp (NBSP). The content of softwood pulp in the pulp slurry is more preferably 25% by mass or more. The upper limit of the content of softwood pulp in the pulp slurry is not particularly limited, but is preferably 45% by mass or less, more preferably 40% by mass or less.

[0058] In the method for producing grease-resistant paper according to this embodiment, the sizing degree of the paper base material is preferably 0 to 5 seconds. This makes it easier to impregnate the paper base material with an oil-resistant agent, thereby improving oil resistance while simultaneously achieving high breathability and high transparency. The sizing degree can be adjusted, for example, by adjusting the amount of internal sizing agent added to the pulp slurry and the amount of external sizing agent applied to the paper base material. For example, the sizing degree of the paper base material can be set to 0 by not adding a sizing agent to the paper base material. Furthermore, while a typical paper machine is equipped with a device called a size press that applies a sizing agent or paper strength agent, it is preferable not to apply the sizing agent or paper strength agent using a size press in the method for producing grease-resistant paper according to this embodiment.

[0059] In the method for producing greaseproof paper according to this embodiment, the basis weight of the paper base material is 20 to 45 g / m 2 It is preferable that the paper substrate has a basis weight of 35 to 42 g / m. This allows for both high breathability and high transparency. 2 It is more preferable that the basis weight of the paper substrate is 20 g / m 2 If the paper base weight is less than 45 g / m, the strength may be insufficient depending on the application. 2 If the thickness exceeds this, the transparency may be insufficient and the visibility of the contents may be poor.

[0060] The oil-proofing agent application step preferably includes a step of allowing the oil-proofing agent to penetrate into the paper substrate, and a step of drying the oil-proofing agent that has penetrated into the paper substrate.

[0061] In the oil-proofing agent application step, the oil-proofing agent penetrates into the paper substrate in the thickness direction. The method for penetrating the oil-proofing agent into the paper substrate is not particularly limited and may be, for example, an impregnation method, a coating method, or a spraying method, with the impregnation method or the coating method being more preferred. The impregnation method is, for example, a dipping impregnation method in which the paper substrate is immersed in a coating liquid containing the oil-proofing agent to impregnate the coating liquid. The coating method is, for example, a method in which the coating liquid is applied to the surface of the paper substrate.

[0062] In the oil-proofing agent application step, various known coating or impregnation devices can be used as appropriate. Examples include a size press, gate roll, and shim sizer. Off-machine coating, which is performed using a coating machine separate from the paper machine, can also be used. Examples include a blade coater, air knife coater, roll coater, bar coater, curtain coater, slot die coater, and gravure coater. The oil-proofing agent layer can be formed on the paper substrate either on-machine or off-machine, but on-machine coating is preferred in terms of production efficiency because it requires less energy. In this embodiment, it is preferable not to apply the oil-proofing agent using a size press, as this makes it easier to adjust the air permeability to a predetermined value or less.

[0063] Additives may be added to the coating solution containing the oil-resistant agent as needed, such as dispersants, antifoaming agents, thickeners, water-resistant agents, plasticizers, fluorescent whitening agents, coloring pigments, coloring dyes, reducing agents, ultraviolet absorbers, antioxidants, fragrances, or deodorizing agents.

[0064] The amount of oil-proofing agent applied (including the amount of coating or impregnation) is determined appropriately according to the basis weight of the paper base so that the content of the oil-proofing agent in the oil-resistant paper is in the range of 7% by mass to 30% by mass, and is not particularly limited, but is preferably 5 to 15 g / m2 in terms of solid content on both sides of the paper base. 2 It is preferable that the density is 7 to 15 g / m 2 It is more preferable that:

[0065] The air permeability of the grease-resistant paper can be adjusted, for example, by adjusting the air permeability and basis weight of the paper base material in the papermaking process, or by adjusting the content of the oil-resistant agent and the basis weight of the grease-resistant paper in the oil-resistant agent application process. [Example]

[0066] The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to these examples. In the examples, "parts" and "%" refer to "parts by mass" and "% by mass", respectively, unless otherwise specified. The number of added parts is a value converted into solid content.

[0067] Example 1 <Paper base material production> 30 parts of softwood pulp (N-BKP) and 70 parts of hardwood pulp (L-BKP) were dispersed in water and mixed, and then beaten using a beater to a pulp freeness of 400 ml according to the Canadian Standard Freeness Test Method specified in JIS P 8121-1995. 0.3 parts of polyamide epichlorohydrin (product name: WS-4030, manufactured by Seiko PMC) and 0.14 parts of aluminum sulfate were added to the pulp slurry as wet strength agents, and the mixture was made into paper on a Fourdrinier machine to a basis weight of 42 g / m. 2 A paper substrate with a base paper air permeability (air permeability of the paper substrate) of 10 seconds was obtained.

[0068] <Oil-resistant agent impregnation> A coating solution containing a fatty acid ester-based oil-resistant agent with a melting point of 85°C (product name: SEIKOAT T-EF201, manufactured by Seiko PMC Co., Ltd.) was applied to the obtained paper substrate at an adjusted concentration, with an impregnation amount of 7 g / m2 in solids. 2 The paper was then dried in a dryer to obtain greaseproof paper.

[0069] Example 2 Impregnation amount: 7g / m 2 from 15g / m 2 Grease-resistant paper was obtained in the same manner as in Example 1, except that the above was changed to

[0070] Example 3 Impregnation amount: 7g / m 2 to 5.1 g / m 2 Grease-resistant paper was obtained in the same manner as in Example 1, except that the above was changed to

[0071] Example 4 Paper base weight: 42 g / m 2 from 35g / m 2 and the air permeability of the base paper was changed from 10 seconds to 8 seconds, and oil-resistant paper was obtained in the same manner as in Example 1.

[0072] Example 5 Paper base weight: 42 g / m 2 from 73 g / m 2 and the air permeability of the base paper was changed from 10 seconds to 20 seconds, and oil-resistant paper was obtained in the same manner as in Example 1.

[0073] Example 6 Grease-resistant paper was obtained in the same manner as in Example 1, except that the pulp freeness of the paper base material was changed from 400 ml to 300 ml and the base paper air permeability was changed from 10 seconds to 25 seconds.

[0074] Example 7 Oil-resistant paper was obtained in the same manner as in Example 1, except that the oil-resistant agent was changed from a fatty acid ester-based oil-resistant agent with a melting point of 85°C (SEIKOAT T-EF201, manufactured by Seiko PMC) to a fatty acid ester-based oil-resistant agent with a melting point of 60°C (K-PON 120, manufactured by Kokura Synthetic Industries Co., Ltd.).

[0075] Example 8 Grease-resistant paper was obtained in the same manner as in Example 1, except that the pulp freeness of the paper base material was changed from 400 ml to 250 ml and the base paper air permeability was changed from 10 seconds to 50 seconds.

[0076] Example 9 Impregnation amount: 7g / m 2 to 13.5g / m 2 Grease-resistant paper was obtained in the same manner as in Example 1, except that the above was changed to

[0077] Comparative Example 1 Impregnation amount: 7g / m 2 to 3 g / m 2 Grease-resistant paper was obtained in the same manner as in Example 1, except that the above was changed to

[0078] Comparative Example 2 Impregnation amount: 7g / m 2 from 20g / m 2 Grease-resistant paper was obtained in the same manner as in Example 1, except that the above was changed to

[0079] Comparative Example 3 Paper base weight: 42 g / m 2 from 218g / m 2 The base paper air permeability was changed from 10 seconds to 50 seconds, and the impregnation amount was changed to 7g / m 2 from 12 g / m 2 Grease-resistant paper was obtained in the same manner as in Example 1, except that the above was changed to

[0080] Comparative Example 4 Grease-resistant paper was obtained in the same manner as in Example 1, except that the oil-resistant agent was changed from a fatty acid ester-based oil-resistant agent with a melting point of 85°C (SEIKOAT T-EF201, manufactured by Seiko PMC) to a microcrystalline wax with a melting point of 84°C (trade name: EMUSTAR-042X, manufactured by Nippon Seiro Co., Ltd.).

[0081] Comparative Example 5 Grease-resistant paper was obtained in the same manner as in Example 1, except that the oil-resistant agent was changed from a fatty acid ester-based oil-resistant agent with a melting point of 85°C (SEIKOAT T-EF201, manufactured by Seiko PMC) to a paraffin wax with a melting point of 69°C (trade name: EMUSTAR-1155, manufactured by Nippon Seiro Co., Ltd.).

[0082] Comparative Example 6 Grease-resistant paper was obtained in the same manner as in Example 1, except that the oil-resistant agent was changed from a fatty acid ester-based oil-resistant agent with a melting point of 85°C (SEIKOAT T-EF201, manufactured by Seiko PMC) to a styrene acrylic resin (St / Ac) with a melting point of 160°C (trade name: SEIKOAT NE-2260, manufactured by Seiko PMC).

[0083] Comparative Example 7 Grease-resistant paper was obtained in the same manner as in Example 1, except that the oil-resistant agent was changed from a fatty acid ester-based oil-resistant agent with a melting point of 85°C (SEIKOAT T-EF201, manufactured by Seiko PMC Co., Ltd.) to polyvinyl alcohol (PVA) with a melting point of 200°C (trade name AP-17, manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.).

[0084] Comparative Example 8 Grease-resistant paper was obtained in the same manner as in Example 1, except that the oil-resistant agent was changed from a fatty acid ester-based oil-resistant agent with a melting point of 85°C (SEIKOAT T-EF201, manufactured by Seiko PMC) to starch with a melting point of 257°C (trade name: FilmKOTE370, manufactured by Ingredion).

[0085] Comparative Example 9 Oil-resistant paper was obtained in the same manner as in Example 1, except that the oil-resistant agent was changed from a fatty acid ester-based oil-resistant agent with a melting point of 85°C (SEIKOAT T-EF201, manufactured by Seiko PMC) to a styrene butadiene latex copolymer (SBR) (trade name: Smartex P-6X20, manufactured by Nippon A&L Co., Ltd.).

[0086] Comparative Example 10 The oil-resistant agent was changed from a fatty acid ester-based oil-resistant agent with a melting point of 85°C (SEIKOAT T-EF201, manufactured by Seiko PMC) to a styrene butadiene latex copolymer (SBR) (product name: Smartex P-6X20, manufactured by Nippon A&L Co., Ltd.), and the impregnation amount was increased to 7 g / m. 2 to 2.4 g / m 2 Grease-resistant paper was obtained in the same manner as in Example 1, except that the above was changed to

[0087] The paper base materials and greaseproof papers of the examples and comparative examples were measured for the following physical properties. The results are shown in Table 1. Physical property measurement conditions Air permeability (air permeability of base paper, air permeability of greaseproof paper) Oken air permeability was measured in accordance with JIS P 8117:2009 Air permeability and low air permeability altitude test method Oken test method. ·Oil resistance Kit oil resistance was measured according to the kit method of JAPAN TAPPI No. 41 Oil Repellency Test Method. A kit oil resistance of 3 or higher was considered to be suitable for practical use. ·Water repellency Water repellency was measured according to the JAPAN TAPPI No. 68 water repellency test method. A water repellency of R8 or higher was considered to be at a practical level. ·Opacity Opacity was measured according to JIS P 8149:2000 Opacity Test Method (Paper Backing) - Diffusion Proof Method. An opacity of 55% or less was considered a practical level. - Cooking oil resistance (salad oil) The sample was pretreated using the method specified in JIS P8111:1998, and one drop (0.03 ml) of salad oil (Nissin Salad Oil / Nissin Oillio Co., Ltd.) was applied to one side of the sample at room temperature using a dropper from a height of 10 mm from the sample. The sample was immediately placed in a hot air dryer chamber heated to 50°C and left to stand for 10 minutes, after which the state of soaking of the salad oil into the paper was evaluated. Evaluation was based on the following four levels, with a rating of C or higher being considered pass and no practical problems. A) No bleeding of salad oil (practical level) B) The salad oil seeps out less than half of the drip area (practical level). C) The salad oil seeps out over half the drip area (lower practical limit). D) Salad oil seeps through to the other side (unsuitable for practical use)

[0088] [Table 1]

[0089] As shown in Table 1, the grease-resistant papers of the Examples had low air permeability and low opacity. Furthermore, the grease-resistant papers of the Examples had high kit oil resistance and excellent resistance to salad oil at 50°C. In contrast, Comparative Example 1 had a low oil-proofing agent content, resulting in high opacity and poor kit oil resistance and resistance to salad oil at 50°C. Comparative Example 2 had a high oil-proofing agent content, resulting in high air permeability. Comparative Example 3 had a high paper base weight, resulting in high base paper air permeability and a low oil-proofing agent content. As a result, resistance to salad oil at 50°C was poor and opacity was high. Comparative Examples 4 and 5 used wax as an oil-proofing agent, resulting in poor kit oil resistance and resistance to salad oil at 50°C. Comparative Example 6 used a styrene-acrylic resin as an oil-proofing agent, resulting in poor water repellency, kit oil resistance, and resistance to salad oil at 50°C. In Comparative Examples 7 and 8, film-forming PVA or starch was used as the oil-resistant agent, resulting in increased air permeability of the grease-resistant paper and poor water repellency and kit oil resistance. In Comparative Examples 9 and 10, film-forming SBR was used as the oil-resistant agent, resulting in increased air permeability of the grease-resistant paper and poor resistance to salad oil at 50°C. In Comparative Example 10, the oil-resistant agent content was reduced to 5.4%, but the air permeability of the grease-resistant paper was not at a practical level.

[0090] The surfaces of the greaseproof papers of Examples 3 and 9, Comparative Examples 9 and 10, and the paper substrates without oil-proofing agents (Reference Examples 1 and 2) were observed using an electron microscope (FE-SEM SU8010, Hitachi High-Tech Corporation). The results are shown in Figures 1 and 2. Figures 1 and 2 are secondary electron images of the surfaces of the greaseproof papers and the paper substrates at 150x and 500x magnification, respectively. (a) is an electron microscope image of Example 9, (b) is an electron microscope image of Example 3, (c) is an electron microscope image of Reference Example 1, (d) is an electron microscope image of Reference Example 2, (e) is an electron microscope image of Comparative Example 10, and (f) is an electron microscope image of Comparative Example 9. Reference Examples 1 and 2 are electron microscope images taken at different positions on the surface of the paper substrate without oil-proofing agents. As shown in Figures 1(c) and 1(d) and Figures 2(c) and 2(d), the unevenness of the pulp fibers that make up the surface of the paper substrate can be seen. In the greaseproof paper of Example 9 shown in Figures 1(a) and 2(a), an oil-resistant agent film was observed, but the film was a discontinuous film with holes or depressions, and the outlines of the pulp fibers constituting the surface of the paper substrate were clearly visible. The greaseproof paper of Example 3 shown in Figures 1(b) and 2(b) was similar to the greaseproof paper of Example 9. In contrast, the greaseproof paper of Comparative Example 10 shown in Figures 1(e) and 2(e) had an oil-resistant agent film that was continuous without holes or depressions, and although the unevenness of the pulp fibers constituting the surface of the paper substrate was slightly visible, the outlines of the pulp fibers were blurred. The greaseproof paper of Comparative Example 9 shown in Figures 1(f) and 2(f) was similar to the greaseproof paper of Comparative Example 10.

[0091] The cross sections of the greaseproof paper of Example 9 and the paper substrate not treated with an oil-proofing agent were observed using SEM-EDS (JSM-IT300 In Touch Scope, manufactured by JEOL Ltd.). The results are shown in Figures 3 and 4. Figure 3 shows the SEM-EDS observation results of the cross section of the greaseproof paper, where (a1) and (a2) are secondary electron images, (b1) and (b2) are elemental mapping images of carbon and oxygen, and (c1) and (c2) are elemental mapping images of carbon. Figure 4 shows the SEM-EDS observation results of the cross section of the paper substrate, where (a1) and (a2) are secondary electron images, (b1) and (b2) are elemental mapping images of carbon and oxygen, and (c1) and (c2) are elemental mapping images of carbon. In Figures 3 and 4, (b1) and (c1) show the elemental distributions of the cross section shown in (a1), while (b2) and (c2) show the elemental distributions of the cross section shown in (a2), which is a different cross section from (a1). Figures 3 and 4 show gray-scaled elemental mapping images. However, the distribution of each element in the elemental mapping image is more accurately represented in the color image before gray-scale processing. In the color elemental mapping image, the distribution of carbon is shown in red, and the distribution of oxygen is shown in green. As shown in Figures 3(a1) and (a2), no oil-resistant coating was observed on the surface of the grease-resistant paper. As shown in Figures 3(b1) and (b2), carbon was more densely distributed around the pulp fibers in the grease-resistant paper than in the paper substrate shown in Figures 4(b1) and (b2). This confirmed that the oil-resistant agent coated the pulp fibers and was distributed throughout the thickness of the grease-resistant paper. As shown in Figures 3(c1) and 3(c2), the greaseproof paper had a higher carbon distribution throughout the thickness direction than the paper substrate shown in Figures 4(c1) and 4(c2). When the carbon ratio was measured on an average cross-sectional surface, the carbon ratio of the paper substrate shown in Figure 4 was 47-48 mass%, while the carbon ratio of the greaseproofing agent shown in Figure 3 was 55-56 mass% on an average cross-sectional surface.

Claims

1. An oil-resistant paper having a paper base material mainly made of pulp containing an oil-resistant agent, The oil-resistant agent contains a fatty acid ester, The content of the fatty acid ester in the oil-resistant paper is 7% by mass or more and 30% by mass or less, JIS P 8117:2009 Air permeability and air permeability low altitude test method The oil-resistant paper characterized in that the air permeability of the oil-resistant paper measured in accordance with the Oken test method is 150 seconds or less.

2. 2. The greaseproof paper according to claim 1, wherein the opacity of the greaseproof paper is 55% or less.

3. 3. The greaseproof paper according to claim 1, wherein the fatty acid ester has a melting point of 75° C. or higher.

4. The greaseproof paper has a basis weight of 35 g / m ２ 80g / m or more ２ 3. The greaseproof paper according to claim 1, wherein:

5. 3. The greaseproof paper according to claim 1, wherein the water repellency of the greaseproof paper measured in accordance with the JAPAN TAPPI No. 68 water repellency test method is R8 or higher.

6. 3. The greaseproof paper according to claim 1, wherein the kit oil resistance of the greaseproof paper measured in accordance with the kit method of JAPAN TAPPI No. 41 Oil Repellency Test is 3 or more.

7. 3. The greaseproof paper according to claim 1, wherein the paper base material does not contain a sizing agent, or the content of the sizing agent in the paper base material is 10 ppm by mass or less.

8. 3. The grease-resistant paper according to claim 1, wherein when the surface of the grease-resistant paper is observed under an electron microscope at a magnification of 150 to 500 times, a film of the grease-resistant agent is observed, and the film of the grease-resistant agent has holes or depressions.

9. 3. The greaseproof paper according to claim 1, wherein the greaseproofing agent is distributed throughout the thickness of the paper base material.

10. 3. The oil-resistant paper according to claim 1, wherein when the surface of the oil-resistant paper is observed using an electron microscope at a magnification of 150 to 500 times, the oil-resistant paper has areas where the spaces between the pulp particles are filled with the oil-resistant agent and areas where the spaces between the pulp particles are not filled with the oil-resistant agent.

11. A method for producing oil-resistant paper in which a paper base material mainly made of pulp contains an oil-resistant agent, a papermaking process for making a paper base material; an oil-proofing agent application step of permeating the paper substrate with a coating liquid containing a fatty acid ester as the oil-proofing agent, The content of the oil-resistant agent in the oil-resistant paper in the oil-resistant agent application step is 7% by mass or more and 30% by mass or less, The method for producing greaseproof paper, characterized in that the air permeability of the greaseproof paper is 150 seconds or less.

12. The method for producing greaseproof paper according to claim 11, characterized in that the papermaking step includes a step of adjusting the air permeability of the paper base material to 25 seconds or less.

13. The method for producing greaseproof paper according to claim 11 or 12, characterized in that the sizing degree of the paper base material is 0 to 5 seconds.

14. The basis weight of the paper base material is 20 to 45 g / m ２ 13. The method for producing greaseproof paper according to claim 11 or 12, wherein

15. 13. The method for producing greaseproof paper according to claim 11 or 12, wherein the air permeability of the paper base material is 10 seconds or less.

Images