Greaseproof paper, food packaging paper, packaging material, packaging bag, and method for manufacturing greaseproof paper

Abstract

To provide oil-resistant paper having high oil resistance durable in actual use and excellent anti-blocking property, food packaging paper, a packaging material, a packaging bag, and a manufacturing method of the oil-resistant paper.SOLUTION: Oil-resistant paper 1 includes a paper substrate 10, an intermediate layer 20, and a surface layer 30. In the oil-resistant paper 1, the intermediate layer 20 is provided on at least one surface of the paper substrate 10, the surface layer 30 is provided on a surface on the opposite side provided with the paper substrate 10 among surfaces of the intermediate layer 20, the intermediate layer 20 contains a polyvinyl alcohol, the surface layer 30 contains a (meth)acrylic resin 32 and a starch particle 31, a kit value of a surface of the surface layer 30 as a measurement surface, measured in accordance with JAPAN TAPPI paper pulp testing method No.41:2000, is 6 or over, and a 360 μm×270 μm imaging photograph obtained by imaging a surface of the surface layer 30 by using a scanning white-light interference microscope with a magnification ratio of 50-folds represents a protrusion shape of the starch particle 31.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to greaseproof paper, food packaging paper, packaging materials, packaging bags, and a method for manufacturing greaseproof paper. [Background technology]

[0002] Greaseproof paper is widely used as a material for packaging bags and containers for cooked foods such as fast food, fried foods, and baked foods that contain a lot of oil and moisture, as well as foods that contain a lot of fats and oils, such as chocolate.

[0003] Generally, fluororesin-based oil-resistant agents are widely used as oil-resistant agents that impart oil resistance to paper, and for example, grease-resistant paper in which an oil-resistant layer is formed by coating a fluororesin-based oil-resistant agent on the surface of a paper substrate, and grease-resistant paper in which a fluororesin-based oil-resistant agent is internally added to a paper substrate are known. However, grease-resistant paper using a fluororesin-based oil-resistant agent is difficult to handle the inert gas generated from the oil-resistant agent during combustion, and there has been a demand for grease-resistant paper that does not contain a fluororesin-based oil-resistant agent.

[0004] As an example of an grease-resistant paper intended to replace such fluororesin-based chemicals, Patent Document 1 discloses an grease-resistant paper having at least two oil-resistant layers on one side of a base paper, in which the oil-resistant component of the oil-resistant layer is obtained by applying an emulsion mainly composed of acrylic resin, and the glass transition temperature of the acrylic resin is 30°C or higher.

[0005] Patent Document 2 discloses grease-resistant food paper in which an oil-resistant synthetic resin layer is formed by coating a paper base material with an acrylic synthetic resin emulsion, the oil-resistant synthetic resin layer having an undercoat layer formed on the surface of the paper base material and an overcoat layer which serves as a surface layer, the undercoat layer resin having a glass transition temperature Tg1 of -30 to 0°C and the overcoat layer resin having a glass transition temperature Tg2 of 0 to 30°C. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-316367 A [Patent Document 2] JP 2006-028697 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, when using an oil-resistant agent such as an acrylic resin disclosed in Patent Document 1 and Patent Document 2, the paper base material is coated so as not to generate pinholes in order to exhibit the oil resistance, resulting in insufficient air permeability, which makes it difficult for water vapor generated from the packaged food to escape from the grease-resistant paper to the outside, loosening the bonds of the pulp fibers that make up the grease-resistant paper. For this reason, the blocking of the conventional grease-resistant paper is deteriorated and the oil resistance is reduced. In particular, when the conventional grease-resistant paper is actually used as a material for the above-mentioned packaging bags and packaging containers, there is a problem that sufficient oil resistance to withstand practical use is not obtained.

[0008] For example, even if the greaseproof paper is generally considered to have a certain degree of oil resistance before use (when unused), when it is actually used as a material for packaging bags or packaging containers, the oil resistance during practical use is insufficient and it is not practical to use. When the inventor studied this phenomenon, he thought that one of the causes is that when food or the like packaged in the greaseproof paper is reheated in a microwave oven, the bonds of the pulp fibers of the greaseproof paper are loosened by the steam generated in the microwave oven, and the oil components contained in the food are easily permeated through the front and back sides of the greaseproof paper. As a result, he thought that even if the greaseproof paper has a certain degree of oil resistance before use, the oil resistance decreases as it is actually used, and it is no longer practical to use.

[0009] As described above, greaseproof paper having high oil resistance sufficient for practical use and excellent blocking resistance has not yet been developed, and there is still room for improvement in this regard.

[0010] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide grease-resistant paper, food packaging paper, packaging material, packaging bags, and a method for manufacturing grease-resistant paper that has high oil resistance that can withstand practical use and excellent blocking resistance. [Means for solving the problem]

[0011] As a result of intensive research by the inventors in order to achieve the above-mentioned object, the inventors have discovered a configuration in which an greaseproof paper comprising a paper base material, an intermediate layer and a surface layer, the intermediate layer being provided on at least one surface of the paper base material, and the surface layer being provided on the surface of the intermediate layer opposite the side on which the paper base material is provided, the intermediate layer containing polyvinyl alcohol, the surface layer containing (meth)acrylic resin and starch particles, the kit value measured in accordance with JAPAN TAPPI Paper and Pulp Test Method No. 41:2000 using the surface of the surface layer as the measurement surface is 6 or more, and protrusions caused by starch particles are present in a 360 μm × 270 μm photograph of the surface of the surface layer taken at a magnification of 50 times using a scanning white light interference microscope. This has led to the completion of the present invention.

[0012] That is, the present invention is as follows.

[0013] (1) The grease-resistant paper comprises a paper base material, an intermediate layer, and a surface layer, the intermediate layer being provided on at least one surface of the paper base material, and the surface layer being provided on a surface of the intermediate layer opposite to the surface on which the paper base material is provided, the intermediate layer containing polyvinyl alcohol, the surface layer containing a (meth)acrylic resin and starch particles, the kit value measured in accordance with JAPAN TAPPI Paper and Pulp Testing Method No. 41:2000 using the surface of the surface layer as a measurement surface is 6 or more, and protrusions caused by the starch particles are present in a 360 μm × 270 μm photograph of the surface of the surface layer taken at a magnification of 50 times using a scanning white light interference microscope. (2) The greaseproof paper according to (1), wherein the starch particles are not gelatinized. (3) In the photograph, the projection shape has a radius of a minimum circumscribed circle of 5 to 30 μm when viewed from above, which is the greaseproof paper according to (1) or (2). (4) The greaseproof paper according to any one of (1) to (3), wherein the number of the protrusions in the photograph is 30 to 350. (5) The greaseproof paper according to any one of (1) to (4), wherein the surface layer contains 10 to 200 parts by mass of the starch particles per 100 parts by mass of the (meth)acrylic resin. (6) The dry adhesion amount of the polyvinyl alcohol in the intermediate layer is 0.2 to 0.6 g / m 2 The greaseproof paper according to any one of (1) to (5) above, (7) The greaseproof paper according to any one of (1) to (6), wherein the intermediate layer is provided on both sides of the paper base material. (8) The intermediate layer is provided on both sides of the paper base material, and the total dry adhesion amount of the polyvinyl alcohol in the intermediate layer on both sides is 0.4 to 1.2 g / m 2 The grease-resistant paper according to (6) is characterized in that (9) The grease-resistant paper according to (7) or (8), wherein the surface layer is provided on both sides of the paper base material via the intermediate layer. (10) The dry adhesion amount of the (meth)acrylic resin in the surface layer is 1.2 to 3.6 g / m per one side of the paper base material. 2 The greaseproof paper according to any one of (1) to (9) above, (11) The greaseproof paper according to any one of (1) to (10), wherein the content of the starch particles in the surface layer is 5 to 70 mass % in terms of solid content. (12) The grease-resistant paper comprises an intermediate layer containing polyvinyl alcohol on the surface of a paper base material, and a surface layer formed by applying a coating liquid containing a (meth)acrylic resin and ungelatinized starch particles on the surface of the intermediate layer. (13) The food packaging paper is used as a material for packaging food, and contains the greaseproof paper according to any one of (1) to (12). (14) A packaging material comprising the greaseproof paper according to any one of (1) to (12). (15) A packaging bag comprising the greaseproof paper according to any one of (1) to (12), the surface layer being disposed on the side in contact with an item to be packaged. (16) The method for producing grease-resistant paper includes the steps of: applying a coating liquid containing polyvinyl alcohol onto the surface of a paper substrate to form an intermediate layer; and applying a coating liquid containing a (meth)acrylic resin and ungelatinized starch particles onto the surface of the intermediate layer to form a surface layer. Effect of the Invention

[0014] According to the present invention, it is possible to provide greaseproof paper, food packaging paper, packaging material, packaging bags, and a method for producing greaseproof paper that have high oil resistance sufficient for practical use and excellent blocking resistance. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view of the greaseproof paper according to the first embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the greaseproof paper according to the second embodiment. [Diagram 3] FIG. 3 is a schematic cross-sectional view of the greaseproof paper according to the third embodiment. [Figure 4] FIG. 4 is a photograph of the surface layer of Example 6 taken with a scanning white light interference microscope. [Diagram 5] FIG. 5 is a photograph of the surface layer of Comparative Example 3 captured by a scanning white light interference microscope. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment for carrying out the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. The present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0017] In the drawings, the same elements are given the same reference numerals, and duplicated explanations are omitted. Furthermore, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

[0018] In addition, in this specification, unless otherwise specified, "(meth)acrylic" includes methacryl and acrylic. For example, (meth)acrylic means methacryl, acrylic, or both. The same applies to other similar terms such as "(meth)acrylate".

[0019] FIG. 1 is a schematic cross-sectional view of the greaseproof paper according to the first embodiment.

[0020] The grease-resistant paper 1 according to this embodiment is a grease-resistant paper 1 including a paper base material 10, an intermediate layer 20, and a surface layer 30, the intermediate layer 20 being provided on at least one surface of the paper base material 10, the surface layer 30 being provided on the surface of the intermediate layer 20 opposite the side of the paper base material 10 on which the intermediate layer 20 is provided, the intermediate layer 20 containing polyvinyl alcohol, and the surface layer 30 containing a (meth)acrylic resin 32 and starch particles 31. In other words, the grease-resistant paper 1 has a configuration in which the paper base material 10, the intermediate layer 20, and the surface layer 30 are laminated in this order.

[0021] The surface layer 30 has a kit value of 6 or more when measured in accordance with JAPAN TAPPI Paper Pulp Test Method No. 41:2000 using its surface as a measurement surface, and in a 360 μm × 270 μm photograph of its surface taken at a magnification of 50 times using a scanning white light interference microscope, protrusions due to starch particles 31 are present.

[0022] The surface layer 30 has not only starch particles 31 arranged so as to be enclosed in the (meth)acrylic resin 32, but also starch particles 31 that are extruded onto the surface. In this way, the starch particles 31 protrude from the surface of the surface layer 30, forming a protruding shape. For example, when the greaseproof paper 1 is used for food packaging bags or packaging materials, the surface layer 30 is the layer that comes into contact with the food to be stored, and when the greaseproof paper 1 is processed into packaging bags or packaging materials, it becomes the inner surface.

[0023] According to this embodiment, it is possible to obtain a greaseproof paper 1 that has high oil resistance sufficient for practical use and also has excellent blocking resistance. In a particularly preferred embodiment, even if the greaseproof paper 1 is a greaseproof paper that does not substantially contain a fluorine-based resin (non-fluorine-based greaseproof paper), it can still exhibit high oil resistance and excellent blocking resistance. Therefore, it can be suitably used as a non-fluorine-based greaseproof paper 1. Note that the term "substantially" does not exclude components that are unavoidably contained or mixed.

[0024] For example, in conventional grease-resistant paper, attempts have been made to impart oil resistance by using an oil-resistant agent such as an acrylic resin in order to eliminate the use of fluororesin. However, even if it is possible to eliminate the use of fluororesin to some extent, the use of such an oil-resistant agent causes problems such as insufficient blocking resistance.

[0025] For this reason, attempts may be made to use titanium oxide inorganic fillers such as kaolin, calcium carbonate, talc, etc. in combination with the coating to suppress blocking. However, even if this improves blocking resistance to some extent, the oil resistance may decrease, and problems may occur in which the coating cannot exhibit a level of oil resistance sufficient for practical use.

[0026] However, the oil-resistant paper 1 of this embodiment does not require the use of inorganic fillers such as kaolin, calcium carbonate, talc, etc., and therefore does not suffer from the various problems mentioned above, and can exhibit high oil resistance and excellent blocking properties that are practically usable.

[0027] Each component will be described below.

[0028] (Paper base material)

[0029] The paper substrate 10 is not particularly limited and can be appropriately selected and used depending on the application, examples of which include bleached or unbleached kraft paper (acidic paper or neutral paper), fine paper, medium quality paper, lightly coated paper, coated paper, liner, semi-glassine paper, glassine paper, one-sided gloss paper, parchment paper, white paperboard, etc. Among these, glassine paper is preferable from the viewpoint of oil resistance.

[0030] Examples of the pulp constituting the paper base material 10 include wood pulp, non-wood pulp, waste paper pulp, and synthetic fiber pulp. Examples of wood pulp include chemical pulp and mechanical pulp of softwood and 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 waste paper pulp include magazine waste paper, flyer waste paper, colored waste paper, newspaper waste paper, Kent waste paper, white waste paper, coated waste paper, photocopy waste paper, and broke waste paper. Examples of synthetic fiber pulp include rayon resin, vinylon resin, polyolefin resin, polyester resin, acrylic resin, polyamide resin, polyphenylene resin, and polyurethane resin.

[0031] 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), and softwood bleached sulfite pulp (NBSP).

[0032] Other 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, defoamers, pitch control agents, slime control agents, etc. may be appropriately selected and used in the paper base material 10 as needed, so long as they do not impair the effects of this embodiment.

[0033] The basis weight of the paper base material 10 is 20 to 150 g / m 2 The lower limit of the basis weight is preferably 25 g / m 2 More preferably, it is 30 g / m or more. 2 More preferably, it is 35 g / m or more. 2 It is even more preferable that the basis weight is 80 g / m or more. 2 More preferably, it is 70 g / m or less. 2 More preferably, it is 60 g / m or less. 2 It is even more preferable that the basis weight is not more than 100%. This basis weight is a value measured based on the basis weight testing method of JIS P 8124: 2011. If the lower limit of the basis weight is within this range, the strength of the greaseproof paper is further improved, and if the upper limit of the basis weight is within this range, the cost is not high.

[0034] The thickness of the paper substrate 10 is preferably 20 to 150 μm. The lower limit of the thickness is more preferably 25 μm or more, even more preferably 30 μm or more, and even more preferably 35 μm or more. The upper limit of the thickness is more preferably 80 μm or less, even more preferably 70 μm or less, and even more preferably 60 μm or less.

[0035] The paper base material 10 can be manufactured by a known method. For example, softwood pulp and hardwood pulp are dispersed in water in a predetermined mass ratio, and the pulp is beaten to a predetermined degree by a beater to obtain a pulp slurry. Then, additives and the like are added to the obtained pulp slurry as desired. The prepared slurry is made into paper using a known papermaking machine such as a Fourdrinier papermaking machine, a cylinder papermaking machine, or a twin-wire papermaking machine to obtain the paper base material 10. The papermaking method is not particularly limited, and either acidic papermaking or neutral papermaking can be selected.

[0036] The degree of beating of the paper base material 10 before size pressing is preferably 40 to 70°SR as measured by the Shopper-Rigler method. The lower limit of the degree of beating is more preferably 45°SR or higher. The upper limit of the degree of beating is more preferably 65°SR or lower. This can further improve the barrier properties of the paper base material 10, and can effectively adjust the degree of polyvinyl alcohol impregnation of the intermediate layer 20.

[0037] (Middle class)

[0038] By providing the intermediate layer 20, the coating liquid that will become the surface layer 30 during manufacturing can be controlled so that it remains uniformly on the surface of the paper base material 10, and sufficient oil resistance can be achieved even with a low adhesion amount of the surface layer 30. Furthermore, by reducing the total adhesion amount of the intermediate layer 20 and the surface layer 30, the texture of the greaseproof paper 1 can be made closer to that of normal paper. Furthermore, by incorporating polyvinyl alcohol in the intermediate layer 20 of the greaseproof paper 1, excellent oil resistance can be imparted to the greaseproof paper 1.

[0039] Examples of the polyvinyl alcohol used in the intermediate layer 20 include unmodified polyvinyl alcohol and modified polyvinyl alcohol, which include fully saponified polyvinyl alcohol and partially saponified polyvinyl alcohol, respectively. Examples of the modified polyvinyl alcohol that can be used include α-olefin modified polyvinyl alcohol, cation modified polyvinyl alcohol, anion modified polyvinyl alcohol, silanol modified polyvinyl alcohol, acetoacetyl modified polyvinyl alcohol, mercapto modified polyvinyl alcohol, etc.

[0040] The saponification degree of polyvinyl alcohol, expressed as the molar ratio of saponified ester groups to the ester groups present before saponification, is preferably 80 to 100%, from the viewpoint of exerting a barrier property sufficient to prevent the surface layer coating liquid (coating liquid constituting the surface layer 30) applied to the surface of the intermediate layer 20 from penetrating to the paper substrate 10. Furthermore, from the viewpoint of imparting appropriate air permeability so as not to trap water vapor derived from food inside the grease-resistant paper bag, this saponification degree is more preferably 90% or more, even more preferably 95% or more, and even more preferably 98% or more.

[0041] From the viewpoints of coatability and barrier property, the degree of polymerization of polyvinyl alcohol is preferably in the range of 200 to 8000. The lower limit of the degree of polymerization is more preferably 300 or more, further preferably 400 or more, and even more preferably 500 or more. The upper limit of the degree of polymerization is more preferably 2500 or less, further preferably 2000 or less, and even more preferably 1800 or less.

[0042] From the viewpoint of further improving the barrier properties of the intermediate layer 20 and the blocking resistance of the greaseproof paper 1, it is preferable that the intermediate layer 20 is made of only polyvinyl alcohol. Here, "only" means that nothing other than the component is actively added or mixed, and does not exclude the inevitable inclusion or mixing. In this case, polyvinyl alcohol can be diluted with water before use to adjust the concentration and viscosity to a level suitable for the coating means. Note that other additives such as dispersants, defoamers, and colorants can also be appropriately selected and used in the intermediate layer 20 as necessary, within a range that does not impair the effects of this embodiment.

[0043] The dry adhesion amount of polyvinyl alcohol in the intermediate layer 20 is 0.2 to 0.6 g / m 2 It is preferable that the dry adhesion amount is 0.25 g / m. For example, when the intermediate layer 20 is provided only on one side of the paper base material 10, the dry adhesion amount is the dry adhesion amount per one side of the paper base material 10. For example, when the intermediate layer 20 and the intermediate layer 40 are provided on both sides of the paper base material 10 with the same area (see FIG. 2, for example), the dry adhesion amount is 1 / 2 the total dry adhesion amount of the intermediate layer 20 and the intermediate layer 40. The lower limit of this dry adhesion amount is 0.25 g / m. 2 More preferably, it is 0.3 g / m or more. 2 The upper limit of the dry coating weight is 0.55 g / m or more. 2 More preferably, it is 0.5 g / m or less. 2 It is even more preferable that:

[0044] (Surface layer)

[0045] The surface layer 30 contains a (meth)acrylic resin 32 and starch particles 31. The combined use of the (meth)acrylic resin 32, which has high barrier properties, and the starch particles 31 contributes to maintaining both oil resistance and blocking resistance at a high level. As described above, the (meth)acrylic resin means an acrylic resin, a methacrylic resin, or both.

[0046] When used as wrapping paper or packaging containers for cooked foods such as fast food, fried foods, and baked foods that contain a lot of oil and moisture, or foods that contain a lot of fats and oils such as chocolate, or as paper coverings such as food trays, there is a problem that the oil resistance of the greaseproof paper cannot be maintained at a high enough level to withstand practical use in practical environments.

[0047] The present inventor studied this problem and came to the following conclusion. First, when the pulp fibers are bonded together by coating the surface of the paper base material 10 with a (meth)acrylic resin having high film-forming properties, the oil resistance of the paper is improved, but the blocking resistance is insufficient. On the other hand, when an acrylic resin having a glass transition point of 30° C. or higher is used in combination or an inorganic filler or polyethylene wax is added in order to improve the blocking resistance, the oil resistance of the greaseproof paper becomes insufficient. Therefore, the inventor thought that such a problem could not be solved by controlling the film-forming properties of the (meth)acrylic resin. Based on this idea, the present inventor further studied intensively and, unexpectedly, by blending polyvinyl alcohol in the intermediate layer 20 and using not only the (meth)acrylic resin 32 but also the starch particles 31 in the surface layer 30, the blocking resistance could be improved without reducing the barrier properties of the surface layer 30. It is considered that this makes it possible to maintain high levels of oil resistance, blocking resistance, and moisture permeability in practical environments (however, the action of this embodiment is not limited to these).

[0048] The (meth)acrylic resin 32 has high barrier properties and excellent water resistance, and also has an effect of improving the oil resistance of the intermediate layer 20. The (meth)acrylic resin 32 is not particularly limited, and any known material can be used.

[0049] The (meth)acrylic resin 32 may be a polymer containing at least a (meth)acrylic monomer as a constituent monomer, and may further contain, as necessary, another monomer copolymerizable with the (meth)acrylic monomer as a constituent monomer.

[0050] The proportion of the (meth)acrylic monomer in the constituent monomers in (meth)acrylic resin 32 is preferably 50 mol % or more, more preferably 70 mol % or more, even more preferably 80 mol % or more, and even more preferably 90 mol % or more, and it is even more preferable that the (meth)acrylic resin 32 is a copolymer essentially consisting of only these monomers.

[0051] The (meth)acrylic monomer is not particularly limited, and examples thereof include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl acrylate; (meth)acrylic acid ester derivatives such as 3-ethoxypropyl acrylate, 3-ethoxybutyl acrylate, and 2-hydroxyethyl (meth)acrylate; aryl acrylates and aralkyl acrylates such as phenyl acrylate and benzyl acrylate; and monoacrylic acid esters of polyhydric alcohols such as diethylene glycol, triethylene glycol, and glycerin.

[0052] The other monomers copolymerizable with the (meth)acrylic monomer are not particularly limited, and examples thereof include styrene-based monomers such as styrene, α-methylstyrene, β-methylstyrene, 2,4-dimethylstyrene, α-ethylstyrene, α-butylstyrene, 4-methoxystyrene, and vinyltoluene, styrene, vinyl acetate, vinyl chloride, vinylidene chloride, (meth)acrylonitrile, ethylene, propylene, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, glycerol mono(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylsilyl acrylate, tert-butyl styrene ... Ethylene glycol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, 1,2-propylene glycol di(meth)acrylate, 1,3-propylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, divinylbenzene, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diallyl (meth)acrylate, glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N,N'-methylenebis(meth)acrylamide, sodium vinyl sulfonate, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphoxyethyl (meth)acrylate ethanolamine half salt, sodium 3-allyloxy-2-hydroxypropanesulfonate, sodium polyoxyethylene styrenated phenyl sulfate, sodium glycerin monoallyl ether monosulfosuccinate, sodium 2-sulfoethyl (meth)acrylate, (meth)acrylamide, n-amyl (meth)acrylate, isoamyl (meth)acrylate, benzo Examples of monomers include diethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, caprolactone-modified (meth)acrylate, acrolein, diacetone (meth)acrylamide, formyl styrene, vinyl methyl ketone, vinyl ethyl ketone, (meth)acryloyloxyalkyl propenal, diacetone (meth)acrylate, acetonyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, diallyl phthalate, and triallyl cyanurate. When other monomers are used, they may be used alone or in combination of two or more. Among these, styrene is particularly preferred from the viewpoint of water resistance.

[0053] The weight average molecular weight of the (meth)acrylic resin 32 is preferably 10,000 to 5,000,000. The lower limit of this weight average molecular weight is more preferably 50,000 or more, and even more preferably 100,000 or more. The upper limit of this weight average molecular weight is more preferably 3,000,000 or less, even more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within such ranges, it is possible to achieve a balance between oil resistance and blocking resistance at an even higher level.

[0054] The (meth)acrylic resin 32 preferably has a glass transition point of -50 to 100° C. The lower limit of the glass transition point is more preferably -30° C. or higher, and even more preferably -20° C. or higher. The upper limit of the glass transition point is more preferably 30° C. or lower, and even more preferably 10° C. or lower. Within such a range, the oil resistance is excellent.

[0055] The dry adhesion amount of the (meth)acrylic resin 32 in the surface layer 30 is 1.2 to 3.6 g / m per one side of the paper base material 10. 2 The lower limit of the dry coating weight is preferably 1.5 g / m 2 More preferably, it is 2.0 g / m or more. 2 The upper limit of the dry coating weight is 3.0 g / m or more. 2 More preferably, it is 2.5 g / m or less. 2 When the dry adhesion amount of the (meth)acrylic resin 32 is within this range, the oil resistance and practical oil resistance can be maintained at a higher level.

[0056] By using the starch particles 31 in combination with the (meth)acrylic resin 32, a sufficient level of oil resistance can be imparted to the surface layer 30. The type of starch particles 31 is not particularly limited, and for example, cereal starches such as rice starch, wheat starch, and corn starch, and tuber starches such as sweet potato starch, potato starch, and tapioca starch can be used. Modified starches can also be used. Examples of modified starches that can be used include acetylated starch, oxidized starch, acetylated adipate crosslinked starch, acetylated phosphate crosslinked starch, sodium octenyl succinate starch, starch acetate, hydroxypropyl starch, hydroxypropyl phosphate crosslinked starch, phosphate monoesterified phosphate crosslinked starch, phosphated starch, phosphate crosslinked starch, sodium starch glycolate, and the like. Among these, cereal starch, acetylated starch, and oxidized starch are preferable. The starch particles 31 may be made of one type of starch or a combination of two or more types of starch.

[0057] The starch particles 31 are preferably not gelatinized. The term "gelatinization" used here means that the granular structure of the starch particles 31 is broken down by heating or alkali treatment of a suspension in which the starch particles 31 are dispersed and suspended in water. Conventionally, in the papermaking industry and the like, when starch is used as a raw material for size press liquid, coated paper paint, internal addition, external addition, and the like, it is common to prepare a suspension of starch, gelatinize it by heating it to a gelatinization temperature or higher, and prepare a starch paste liquid for use. On the other hand, in this embodiment, the starch particles 31 are not gelatinized, so that they can be present in the surface layer 30 in a state that is not too small. By containing such non-gelatinized starch particles 31 in the surface layer 30 together with the (meth)acrylic resin 32, it is possible to achieve both oil resistance and blocking resistance at a higher level (however, the action of this embodiment is not limited to this).

[0058] From the above viewpoint, in this embodiment, the protruding shape of the starch particles 31 is present in a 360 μm×270 μm photograph of the surface of the surface layer 30 taken at a magnification of 50 times by a scanning white light interference microscope. This means that the surface of the surface layer 30 is not smooth, but has a more uneven surface state, compared to, for example, a surface layer containing only a resin component such as a conventional acrylic resin, or a surface layer containing such a resin component and an inorganic filler (see FIG. 1, etc.). By having the starch particles 31 exist in such a protruding shape in the surface layer 30, it is possible to achieve both oil resistance and blocking resistance at a higher level. In particular, when the above-mentioned ungelatinized starch particles 31 are used, they can be present in the surface layer 30 in a state where they are not too small, and therefore such a protruding shape can be efficiently formed, which is preferable.

[0059] The "projection shape" here refers to a surface having a height difference of 5 μm or more in the above-mentioned photograph. This height difference can be confirmed by a 360 μm×270 μm photograph taken at a magnification of 50 times by the above-mentioned scanning white light interference microscope. The scanning white light interference microscope can obtain surface height information from interference fringes based on the brightness and darkness of light, so that the presence or absence of such a projection shape can be confirmed with high accuracy. In this respect, when the surface layer is composed only of a resin component, or when the surface layer is filled with an inorganic filler such as kaolin, calcium carbonate, talc, or titanium, a surface state with unevenness to the extent that oil resistance and blocking resistance can be sufficiently exhibited cannot be formed. However, in this embodiment, starch particles 31 are added to the surface layer 30, and some of the particles can be made to protrude from the surface, so that such a projection shape can be formed on the surface layer 30. In this way, a surface state with unevenness to the extent that oil resistance and blocking resistance can be sufficiently exhibited is formed (however, the action of this embodiment is not limited to this).

[0060] From the viewpoint of achieving both oil resistance and blocking resistance at a higher level, the projection shape is preferably non-fibrous, for example, approximately spherical (see, for example, the shape of starch particles 31 exposed on the surface of surface layer 30 in FIG. 1). The number and shape of the projections on surface layer 30 (whether or not they are non-fibrous, such as approximately spherical) can be confirmed from a 360 μm×270 μm photograph taken at a magnification of 50 times using the above-mentioned scanning white light interference microscope.

[0061] From this viewpoint, in the above-mentioned photograph, the projection shape preferably has a radius of the minimum circumscribing circle in top view of 5 to 30 μm. The upper limit of this radius is more preferably 25 μm or less, and even more preferably 20 μm or less. By using such a size and shape of the projection shape, it is possible to easily form a uniform oil-proofing agent layer, so that it is possible to achieve both oil resistance and blocking resistance at a higher level. In particular, when the above-mentioned ungelatinized starch particles 31 are used, they can be present in the surface layer 30 in a state where they are not too small, so that a projection shape having a radius of the minimum circumscribing circle in such a range can be efficiently formed. On the other hand, for example, with a fibrous inorganic filler, it is not possible to form a projection shape having such a radius of the minimum circumscribing circle on the surface of the surface layer. This radius of the minimum circumscribing circle can be obtained by the method described in the examples described later.

[0062] In addition, in a 360 μm×270 μm photograph of the surface of the surface layer 30 taken at a magnification of 50 times by a scanning white light interference microscope, it is preferable that there are 30 to 350 protrusions of the starch particles 31. The lower limit of this number is more preferably 50 or more, and even more preferably 70 or more. The upper limit of this number is more preferably 320 or less, and even more preferably 300 or less. By setting the density of the protrusions of the starch particles 31 within this range, it is possible to achieve both oil resistance and blocking resistance at a higher level. Note that the number of protrusions referred to here is counted as one even when only a part of the protrusions is imaged within the imaging range, and can be determined by the method described in the Examples below.

[0063] The surface layer 30 preferably contains 10 to 200 parts by mass of starch particles per 100 parts by mass of the (meth)acrylic resin. The lower limit of the content of the starch particles is more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more. The upper limit of the content of the starch particles is more preferably 150 parts by mass or less, and even more preferably 100 parts by mass or less.

[0064] The content of starch particles in the surface layer 30 is preferably 5 to 70% by mass, calculated as solid content. The lower limit of this content is more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit of this content is more preferably 66% by mass or less, and even more preferably 60% by mass or less.

[0065] The dry adhesion amount of starch particles in the surface layer 30 is 0.4 to 2.8 g / m per one side of the paper base material 10. 2 The lower limit of the dry coating weight is preferably 0.7 g / m 2 More preferably, it is 1.0 g / m or more. 2 The upper limit of the dry coating weight is 2.0 g / m or more. 2 More preferably, it is 1.5 g / m or less. 2When the dry adhesion amount of the starch particles is within such a range, the oil resistance and practical oil resistance can be maintained at a higher level.

[0066] In a preferred embodiment of the present invention, the surface layer 30 is preferably substantially free of inorganic fillers such as kaolin, calcium carbonate, talc, and titanium. Even without such inorganic fillers, high oil resistance and excellent blocking properties can be maintained. Furthermore, by substantially not including inorganic fillers, the surface layer 30 can be provided with the advantage that the oil resistance is less likely to decrease.

[0067] Other additives such as a dispersant, an antifoaming agent, and a colorant may be appropriately selected and used as necessary in the surface layer 30 within a range that does not impair the effects of the present embodiment. In addition, it is preferable that the surface layer 30 does not contain a fluorine-based resin.

[0068] According to this embodiment, the surface layer 30 may be a single layer, or may be a multi-layer structure of two or more layers.

[0069] Furthermore, according to this embodiment, in addition to the intermediate layer 20 and the surface layer 30, other functional layers (e.g., a printing layer, a print-receiving layer, an adhesive layer for bag-making processing) may be provided. For example, a functional layer such as a printing layer or a cover layer may be provided on the surface of the surface layer 30. For example, when used as a food packaging bag, a printing layer may not be provided on the inner surface that comes into contact with the food, but a printing layer may be provided on the outer surface.

[0070] The thickness of the greaseproof paper 1 is preferably 20 to 150 μm. The lower limit of this thickness is more preferably 30 μm or more, even more preferably 35 μm or more, and even more preferably 40 μm or more. The upper limit of this thickness is more preferably 100 μm or less, even more preferably 80 μm or less, and even more preferably 70 μm or less. If the thickness is within this range, sufficient strength and oil resistance can be imparted to the paper for use as a base material for food packaging.

[0071] The grease-resistant paper 1 has a kit value of 6 or more, preferably 7 or more, and more preferably 8 or more, measured according to JAPAN TAPPI Paper and Pulp Test Method No. 41:2000 with the surface of the surface layer 30 as the measurement surface. If the kit value of the grease-resistant paper 1 having the configuration of this embodiment is 6 or more, it can exhibit high oil resistance (particularly practical oil resistance) and excellent blocking resistance that can withstand practical use as an grease-resistant paper used under standard environments, in combination with the above-mentioned protrusion shape of the surface layer 30. The practical oil resistance here refers to, for example, the difficulty of oil stains that appear when edible oil actually used is dropped onto the surface layer 30 of the grease-resistant paper and penetrates into the inside from the surface layer 30. A specific method for evaluating practical oil resistance is as described in the examples described later.

[0072] FIG. 2 is a schematic cross-sectional view of the greaseproof paper according to the second embodiment.

[0073] The grease-resistant paper 2 according to this embodiment differs from the grease-resistant paper 1 shown in Fig. 1 in that intermediate layers 20, 40 are provided on both sides of the paper base material 10. Thus, according to this embodiment, the intermediate layer 20 (for example, on the inner side that encases food when used as a packaging bag for food, etc.) and the intermediate layer 40 (for example, on the outer side when used as a packaging bag for food, etc.) may be provided on both sides of the paper base material 10. This intermediate layer 40 can be formed by a method similar to the method for forming the intermediate layer 20 described above.

[0074] When the intermediate layers 20, 40 are provided on both sides of the paper base material 10, the total dry adhesion amount of polyvinyl alcohol in the intermediate layers 20, 40 on both sides of the paper base material 10 is 0.4 to 1.2 g / m 2 The total amount of dry adhesion is preferably 1 m 2 This refers to the total dry adhesion amount of polyvinyl alcohol on the entire paper base material 10, and refers to the dry adhesion amount on both sides. That is, in the case of the paper base material 10, it refers to the sum of the dry adhesion amount of polyvinyl alcohol on the intermediate layer 20 and the dry adhesion amount of polyvinyl alcohol on the intermediate layer 40. The lower limit of this total amount is 0.45 g / m 2 More preferably, it is 0.55 g / m or more. 2More preferably, it is 0.6 g / m or more. 2 It is even more preferable that the total amount is equal to or more than 1.1 g / m. 2 More preferably, it is 1.0 g / m or less. 2 More preferably, it is 0.9 g / m or less. 2 Even more preferably, it is:

[0075] FIG. 3 is a schematic cross-sectional view of the greaseproof paper according to the third embodiment.

[0076] The grease-resistant paper 3 according to this embodiment differs from the grease-resistant paper 1 shown in Fig. 1 in that intermediate layers 20, 40 are provided on both sides of the paper base material 10, and surface layers 30, 50 are also provided on both sides of the paper base material 10. That is, the grease-resistant paper 3 is an embodiment in which a surface layer 50 is further provided on the surface of the intermediate layer 40 of the grease-resistant paper 2 shown in Fig. 2. The surface layer 50, like the surface layer 30, contains a (meth)acrylic resin 52 and starch particles 51.

[0077] In this manner, in this embodiment, the surface layers 30, 50 may be provided on both sides of the paper base material 10 via the intermediate layers 20, 40. For example, when used as a packaging bag for food or the like, the surface layer 30 becomes the inner side that encases the food, and the surface layer 50 becomes the outer side. The surface layer 50 can be formed by the same method as the method for forming the surface layer 30 described above. The material, dimensions, shape, etc. of the surface layer 50 may be the same as or different from the surface layer 30.

[0078] (Manufacturing method)

[0079] The manufacturing method of the greaseproof papers 1, 2, 3 according to the present embodiment is preferably a manufacturing method of greaseproof papers including the steps of (1) applying a coating liquid containing polyvinyl alcohol onto the surface of the paper base material 10 to form the intermediate layer 20, 40, and (2) applying a coating liquid containing a (meth)acrylic resin 32, 52 and ungelatinized starch particles 31, 51 onto the surface of the intermediate layer 20, 40 to form the surface layer 30, 50. According to this manufacturing method, the greaseproof paper 1 having the structure shown in Figure 1, the greaseproof paper 2 having the structure shown in Figure 2, and the greaseproof paper 3 having the structure shown in Figure 3 can be appropriately and suitably manufactured.

[0080] Since the coating liquid containing the (meth)acrylic resin 32, 52 and the above-mentioned ungelatinized starch particles 31, 51 does not need to be gelatinized, it is preferable to prepare the coating liquid while maintaining a temperature below the gelatinization temperature of the starch particles 31, 51 used. Furthermore, it is preferable to coat the coating liquid while maintaining a temperature below the gelatinization temperature of the starch particles 31, 51 to form a coating film on the intermediate layer 20, 40, and then dry the solvent contained in the coating film to form the surface layer 30, 50. Therefore, a more preferred specific example of step (2) is a step of preparing a coating liquid containing the (meth)acrylic resin 32,52 and ungelatinized starch particles 31,51 while maintaining a temperature below the gelatinization temperature of the starch particles 31,51, then coating the coating liquid on the surface of the intermediate layer 20,40 at a temperature below the gelatinization temperature of the starch particles 31,51 to form a coating film on the intermediate layer 20,40, and then drying the solvent contained in the coating film to form the surface layer 30,50. This allows the above-mentioned protrusion shape to be efficiently formed on the surface of the surface layer 30,50.

[0081] Furthermore, from the viewpoint of maintaining a temperature below the gelatinization temperature so as not to cause gelatinization, the preparation of the coating solution and the formation of the coating film in the step (2) are preferably carried out while maintaining a temperature below 52°C, preferably at 50°C or less, more preferably at 40°C or less, and even more preferably at 30°C or less. By maintaining such a temperature range, it is possible to effectively prevent the starch particles 31, 51 from unintentionally gelatinizing. Note that, from the viewpoint of efficiently preparing the coating solution and applying it to the intermediate layer 20, 40, the lower limit of the temperature is preferably 10°C or more, more preferably 15°C or more, and even more preferably 20°C or more. Note that the drying of the coating film can usually be carried out at a temperature of 70 to 130°C.

[0082] As another aspect of this embodiment, the greaseproof paper 1, 2, 3 can be made to include an intermediate layer 20, 40 containing polyvinyl alcohol on the surface of the paper base material 10, and a surface layer 30, 50 formed by applying a coating liquid containing a (meth)acrylic resin 32, 52 and ungelatinized starch particles 31, 51 on the surface of the intermediate layer 20, 40. Even in this aspect, it is possible to obtain a greaseproof paper having high oil resistance to a level that can withstand practical use and excellent blocking resistance. Also in this case, as described above, since the coating liquid containing the (meth)acrylic resin 32, 52 and the ungelatinized starch particles 31, 51 does not need to be gelatinized, it is preferable that the coating liquid containing the (meth)acrylic resin 32, 52 and the ungelatinized starch particles 31, 51 is applied to the surface of the intermediate layer 20, 40 by heating it at a temperature lower than the gelatinization temperature of the starch particles 31, 51 or without heating it, thereby forming the surface layer 30, 50.

[0083] The method for forming the intermediate layer 20, 40 is preferably an external addition method in which coating and / or impregnation is performed after papermaking of the paper base material 10. For example, the intermediate layer coating liquid is made into an aqueous dispersion having a solid content concentration of 0.01 to 30% by mass, and the intermediate layer 20, 40 can be formed on one side or both sides of the paper base material 10 using a coating machine such as a bar coater, die coater, gravure coater, roll coater, blade coater, air knife coater, or size press coater. An air knife coater or size press coater is preferred because it is easy to localize the components of the intermediate layer 20, 40 near the surface layer of the paper base material 10.

[0084] As the coating liquid for forming the intermediate layers 20, 40 (coating liquid for intermediate layers), solvents such as water, alcohols (e.g., alkyl alcohols such as methanol, ethanol, isopropanol, etc.; glycols such as ethylene glycol, propylene glycol, diethylene glycol, etc.) can be used, and an aqueous solvent is preferable, with water being more preferable.

[0085] As the coating liquid for forming the surface layer 30, 50 (surface layer coating liquid), a solvent such as water or alcohols (e.g., alkyl alcohols such as methanol, ethanol, isopropanol, etc.; glycols such as ethylene glycol, propylene glycol, diethylene glycol, etc.) can be used, and an aqueous solvent is preferable, and water is more preferable. The starch particles 31, 51 are preferably coated in a state in which they have not been subjected to a gelatinization treatment. As a result, as described above, the starch particles 31, 51 can be present in the surface layer 30, 50 without becoming too small, making it easy to form a protrusion shape.

[0086] The method for forming the surface layers 30, 50 is preferably an external addition method, similar to the intermediate layers 20, 40. For example, the surface layer coating liquid is made into an aqueous dispersion having a solid content concentration of 0.01 to 10% by mass, and the surface layer 30 can be formed on the surface having at least the intermediate layer 20 using a coater such as a bar coater, die coater, gravure coater, roll coater, blade coater, air knife coater, or size press coater. A bar coater or air knife coater is preferred because it is easy to form a uniform coating film.

[0087] After coating, the grease-resistant papers 1, 2, and 3 may be subjected to a calendering process using a calendering device such as a machine calender, a heat calender, a super calender, or a soft calender.

[0088] As described above, the grease-resistant papers 1, 2, and 3 of this embodiment can be suitably used as wrapping paper or packaging containers for cooked foods such as fast food, fried foods, and baked foods that contain a lot of oil and moisture, and foods that contain a lot of fats and oils, such as chocolate, or as paper coverings for food trays, etc.

[0089] Therefore, the food packaging paper is used as a material for packaging food, and can be suitably used as a food packaging paper including the grease-resistant papers 1, 2, and 3 according to the present embodiment. Also, the food packaging paper can be suitably used as a packaging material including the grease-resistant papers 1, 2, and 3. Furthermore, the food packaging paper can be suitably used as a packaging bag including the grease-resistant papers 1, 2, and 3, with the surface layers 30 and 50 being disposed on the side in contact with the packaged item. EXAMPLES

[0090] The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to the following examples. Note that percentages and parts are based on mass unless otherwise specified.

[0091] <Example 1>

[0092] (Preparation of Paper Base Material 10)

[0093] Pulp consisting of 25% by mass of softwood bleached kraft pulp (NBKP) and 75% by mass of hardwood bleached kraft pulp (LBKP) was beaten to a degree of beating of 55°SR according to the Shopper-Rigler method, and dispersed in water to a pulp slurry concentration of approximately 2.7% by mass to obtain a pulp slurry.

[0094] To 100 parts by mass of pulp in this pulp slurry, 2.0 parts by mass of a sizing agent (manufactured by Arakawa Chemical Industries, Ltd., product name: Sizepine N-775), 1.0 part by mass of starch (manufactured by GSL Japan, Inc., product name: Geltron 245), 1.3 parts by mass of a wet strength agent (manufactured by Seiko PMC Corporation, product name: Shikiryoku WS-4020), and 4.0 parts by mass of aluminum sulfate (manufactured by Asahi Chemical Industries, Ltd., liquid aluminum sulfate) were added, and the slurry was spun to a thickness of 60 μm and a basis weight of 40 g / m using a Fourdrinier multi-cylinder papermaking machine. 2 The glassine paper was made into a paper base material 10. The starch was dispersed in water to prepare a suspension, and heated to a gelatinization temperature or higher to be gelatinized before use.

[0095] (Formation of intermediate layers 20, 40)

[0096] A coating solution for an intermediate layer (coating solution for an intermediate layer) containing 3.0 parts by mass of polyvinyl alcohol (PVA, manufactured by Kuraray Co., Ltd., product name: RS-2117, saponification degree 98 mol%) and 97.0 parts by mass of water was applied to both sides of the obtained paper base material 10 by a size press until the total amount of coating (wet adhesion amount) on both sides of the paper base material 10 was 20 g / m 2 The total amount of polyvinyl alcohol applied on both sides was 0.6 g / m 2 (Dry adhesion on one side is 0.3g / m 2 ) was.

[0097] (Formation of surface layer 30)

[0098] Next, 100 parts by mass of styrene-acrylic resin (manufactured by BASF, product name: Joncryl DFC 3030), 33 parts by mass of starch particles (ungelatinized rice starch particles, manufactured by Matsutani Chemical Industry Co., Ltd., product name: Matsutani Kikyo), and 532 parts by mass of water were mixed using an air knife in a papermaking machine while maintaining a temperature below the gelatinization temperature, to prepare a coating liquid for the surface layer (coating liquid for the surface layer) containing these. Then, this coating liquid for the surface layer was applied at a coating amount of 20 g / m while maintaining a temperature below the gelatinization temperature. 2 The solvent was then dried to form the surface layer 30. The styrene-acrylic resin (dry adhesion amount 3.0 g / m 2 ) and rice starch particles (dry adhesion amount 1.0 g / m 2 ) total dry adhesion is 4.0g / m 2 Thereafter, a calendaring process was performed so that the thickness of the paper became 60 μm, and greaseproof paper 2 (sample) having the structure shown in FIG.

[0099] (Kit value of surface layer 30, and number and diameter of protrusions (radius of protrusions) of starch particles)

[0100] The Kit value was measured on the surface of the surface layer 30 in accordance with JAPAN TAPPI Paper and Pulp Testing Method No. 41: 2000. As a result, the Kit value was 12 or more.

[0101] The surface state of the surface layer 30 was confirmed by taking images using a scanning white light interference microscope under the following conditions.

[0102] Using a scanning white light interference microscope (Hitachi High-Tech Science Corporation, device name: scanning white light interference microscope VS1550), the surface layer 30 was imaged at a magnification of 50 times (objective lens: 50 times, intermediate lens: 1.0 times), and a photograph with a measurement range of 360 μm × 270 μm was obtained by performing tilt correction and cylindrical correction. In the obtained photograph, the presence of protrusions of starch particles with a height difference of 5 μm or more was confirmed. The shape of the protrusions was non-fibrous and approximately spherical due to the particle shape of ungelatinized starch particles.

[0103] In the above photograph, the number of protrusions of starch particles in the imaging range of 360 μm × 270 μm was 147, as shown in Table 1. The number of protrusions here refers to those with a height difference of 5 μm or more, and even if only a part of the protrusion was captured in the imaging range, it was counted as one.

[0104] Then, for each protrusion shape viewed from above in the above photograph, the minimum circumscribing circle was hypothesized and its radius (protrusion radius) was measured. The protrusion radius of the protrusion shape in the photograph was then divided by the number of protrusions to obtain the arithmetic average value per protrusion shape, which was taken as the "protrusion radius." As shown in Table 1, this protrusion radius was 5 μm.

[0105] <Example 2>

[0106] (Preparation of Paper Base Material 10) In the same manner as in Example 1, a paper base 10 was obtained.

[0107] (Formation of intermediate layers 20, 40) In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0108] (Formation of surface layer 30)

[0109] Next, 100 parts by mass of acrylic resin (Seiko PMC, product name: Hi-Los X-PE-2273), 33 parts by mass of starch particles (ungelatinized rice starch particles, Matsutani Chemical Industry, product name: Matsutani Kikyo), and 532 parts by mass of water were mixed in the air knife of the papermaking machine while maintaining a temperature below the gelatinization temperature to prepare a surface layer coating liquid containing these. Then, this surface layer coating liquid was applied at a coating amount of 20 g / m2 while maintaining a temperature below the gelatinization temperature. 2 The acrylic resin (dry adhesion amount 3.0 g / m) was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a coating composition having a thickness of 100 μm or more, and the solvent was dried to form the surface layer 30. 2 ) and rice starch particles (dry adhesion amount 1.0 g / m 2 ) total dry adhesion is 4.0g / m 2 Thereafter, a calendaring process was performed so that the thickness of the paper became 60 μm, and greaseproof paper 2 (sample) having the structure shown in FIG.

[0110] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was confirmed to have a protruding shape of starch particles by imaging the surface layer 30 using a scanning white light interference microscope under the same measurement conditions as in Example 1. The protruding shape was non-fibrous and approximately spherical, derived from the particle shape of ungelatinized starch particles.

[0111] The number of protrusions of starch particles in an image area of ​​360 μm × 270 μm in the obtained photograph is shown in Table 1. Then, the protrusion diameter (protrusion radius) of the protrusions of the starch particles in the obtained photograph was measured in the same manner as in Example 1. The results are shown in Table 1.

[0112] <Example 3>

[0113] (Preparation of Paper Base Material 10) In the same manner as in Example 1, a paper base 10 was obtained.

[0114] (Formation of intermediate layers 20, 40) In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0115] (Formation of surface layer 30)

[0116] Next, 100 parts by mass of acrylic resin (Seiko PMC, product name: Hi-Los X-PE-2273), 20 parts by mass of starch particles (ungelatinized rice starch particles, Matsutani Chemical Industry, product name: Matsutani Kikyo), and 280 parts by mass of water were mixed in the air knife of the papermaking machine while maintaining a temperature below the gelatinization temperature to prepare a surface layer coating liquid containing these. Then, this surface layer coating liquid was applied at a coating amount of 20 g / m2 while maintaining a temperature below the gelatinization temperature. 2 The acrylic resin (dry adhesion amount 3.0 g / m) was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a coating composition having a thickness of 100 μm or more, and the solvent was dried to form the surface layer 30. 2 ) and rice starch particles (dry adhesion amount 1.0 g / m 2 ) total dry adhesion is 4.0g / m 2 Thereafter, a calendaring process was performed so that the thickness of the paper became 60 μm, and greaseproof paper 2 (sample) having the structure shown in FIG.

[0117] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was confirmed to have a protruding shape of starch particles by imaging the surface layer 30 using a scanning white light interference microscope under the same measurement conditions as in Example 1. The protruding shape was non-fibrous and approximately spherical, derived from the particle shape of ungelatinized starch particles.

[0118] In addition, the number of protrusions of starch particles in an image area of ​​360 μm × 270 μm in the obtained photograph is shown in Table 1. Then, the protrusion diameter (protrusion radius) of the protrusions of the starch particles in the obtained photograph was measured in the same manner as in Example 1. The results are shown in Table 1.

[0119] <Example 4>

[0120] (Preparation of Paper Base Material 10) In the same manner as in Example 1, a paper base 10 was obtained.

[0121] (Formation of intermediate layers 20, 40) In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0122] (Formation of surface layer 30)

[0123] Next, 100 parts by mass of acrylic resin (Seiko PMC, product name: Hi-Los X-PE-2273), 100 parts by mass of starch particles (ungelatinized rice starch particles, Matsutani Chemical Industry, product name: Matsutani Kikyo), and 300 parts by mass of water were mixed in the air knife of the papermaking machine while maintaining a temperature below the gelatinization temperature to prepare a surface layer coating liquid containing these. Then, this surface layer coating liquid was applied at a coating amount of 20 g / m2 while maintaining a temperature below the gelatinization temperature. 2 The acrylic resin (dry adhesion amount 3.0 g / m) was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a coating composition having a thickness of 100 μm or more, and the solvent was dried to form the surface layer 30. 2 ) and rice starch particles (dry adhesion amount 1.0 g / m 2 ) total dry adhesion is 4.0g / m 2 Thereafter, a calendaring process was performed so that the thickness of the paper became 60 μm, and greaseproof paper 2 (sample) having the structure shown in FIG.

[0124] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was confirmed to have a protruding shape of starch particles by imaging the surface layer 30 using a scanning white light interference microscope under the same measurement conditions as in Example 1. The protruding shape was non-fibrous and approximately spherical, derived from the particle shape of ungelatinized starch particles.

[0125] The number of protrusions of starch particles in an image area of ​​360 μm × 270 μm in the obtained photograph is shown in Table 1. Then, the protrusion diameter (protrusion radius) of the protrusions of the starch particles in the obtained photograph was measured in the same manner as in Example 1. The results are shown in Table 1.

[0126] <Example 5>

[0127] (Preparation of Paper Base Material 10) In the same manner as in Example 1, a paper base 10 was obtained.

[0128] (Formation of intermediate layers 20, 40) In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0129] (Formation of surface layer 30)

[0130] Next, 100 parts by mass of acrylic resin (Seiko PMC, product name: Hi-Los X-PE-2273), 33 parts by mass of acetylated starch particles (ungelatinized acetylated starch particles, Showa Sangyo, product name: Mermaid MC3000), and 198 parts by mass of water were mixed in an air knife of a papermaking machine while maintaining a temperature below the gelatinization temperature to prepare a surface layer coating liquid containing these. Then, this surface layer coating liquid was applied at a coating amount of 20 g / m while maintaining a temperature below the gelatinization temperature. 2 The acrylic resin (dry adhesion amount 3.0 g / m) was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a coating composition having a thickness of 100 μm or more, and the solvent was dried to form the surface layer 30. 2 ) and acetylated starch particles (dry coating weight 1.0 g / m 2 ) total dry adhesion is 4.0g / m 2 Thereafter, a calendaring process was performed so that the thickness of the paper became 60 μm, and greaseproof paper 2 (sample) having the structure shown in FIG.

[0131] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was confirmed to have a protruding shape of starch particles by imaging the surface layer 30 using a scanning white light interference microscope under the same measurement conditions as in Example 1. The protruding shape was non-fibrous and approximately spherical, derived from the particle shape of ungelatinized starch particles.

[0132] In addition, the number of protrusions of starch particles in an image area of ​​360 μm × 270 μm in the obtained photograph is shown in Table 1. Then, the protrusion diameter (protrusion radius) of the protrusions of the starch particles in the obtained photograph was measured in the same manner as in Example 1. The results are shown in Table 1.

[0133] <Example 6>

[0134] (Preparation of Paper Base Material 10) In the same manner as in Example 1, a paper base 10 was obtained.

[0135] (Formation of intermediate layers 20, 40) In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0136] (Formation of surface layer 30)

[0137] Next, 100 parts by mass of acrylic resin (Seiko PMC, product name: Hi-Los X PE-2273), 33 parts by mass of oxidized starch particles (ungelatinized oxidized starch particles, Oji Cornstarch, product name: Ace A), and 198 parts by mass of water were mixed in an air knife of a papermaking machine while maintaining a temperature below the gelatinization temperature to prepare a surface layer coating liquid containing these. Then, this surface layer coating liquid was applied at a coating amount of 20 g / m while maintaining a temperature below the gelatinization temperature. 2 The acrylic resin (dry adhesion amount 3.0 g / m) was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a coating composition having a thickness of 100 μm or more, and the solvent was dried to form the surface layer 30. 2 ) and acetylated starch particles (dry coating weight 1.0 g / m 2) total dry adhesion is 4.0g / m 2 Thereafter, a calendaring process was performed so that the thickness of the paper became 60 μm, and greaseproof paper 2 (sample) having the structure shown in FIG.

[0138] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was confirmed by imaging the surface layer 30 under the same measurement conditions as in Example 1 using a scanning white light interference microscope, and the surface had the protrusion shape of starch particles (see FIG. 4). The protrusion shape was non-fibrous and approximately spherical, derived from the particle shape of ungelatinized starch particles.

[0139] Furthermore, in the obtained photograph, the number of protrusions of the oxidized starch particles in an image area of ​​360 μm × 270 μm is shown in Table 1. Then, the protrusion diameter (protrusion radius) of the protrusions of the starch particles in the obtained photograph was measured in the same manner as in Example 1. The results are shown in Table 1.

[0140] <Comparative Example 1>

[0141] (Preparation of Paper Base Material 10)

[0142] In the same manner as in Example 1, a paper base 10 was obtained.

[0143] (Formation of intermediate layers 20, 40)

[0144] In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0145] (Formation of surface layer 30)

[0146] Next, a coating solution for a surface layer (coating solution for a surface layer) containing 100 parts by mass of a styrene-acrylic resin (manufactured by BASF, product name: Joncryl DFC 3030) and 150 parts by mass of water was applied at a coating amount of 20 g / m using the air knife of the papermaking machine. 2The styrene-acrylic resin was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a dry coating amount of 4.0 g / m2. 2 Thereafter, the paper was subjected to a calendar treatment so that the thickness of the paper became 60 μm, and an greaseproof paper (sample) was obtained.

[0147] The kit value of this surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was imaged using a scanning white light interference microscope under the same measurement conditions as in Example 1, but no protrusion shapes were observed.

[0148] <Comparative Example 2>

[0149] (Preparation of Paper Base Material 10)

[0150] In the same manner as in Example 1, a paper base 10 was obtained.

[0151] (Formation of intermediate layers 20, 40)

[0152] In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0153] (Formation of surface layer 30)

[0154] Next, a coating solution for the surface layer (coating solution for the surface layer) containing 100 parts by mass of an acrylic resin (manufactured by Seiko PMC Corporation, product name: Hi-Loss X-PE-2273) and 150 parts by mass of water was applied at a coating amount of 20 g / m using the air knife of the papermaking machine. 2 The acrylic resin was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a dry coating amount of 4.0 g / m2. 2 Thereafter, the paper was subjected to a calendar treatment so that the thickness of the paper became 60 μm, and an greaseproof paper (sample) was obtained.

[0155] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was imaged using a scanning white light interference microscope under the same conditions as in Example 1, but no protrusions were observed.

[0156] <Comparative Example 3>

[0157] (Preparation of Paper Base Material 10)

[0158] In the same manner as in Example 1, a paper base 10 was obtained.

[0159] (Formation of intermediate layers 20, 40)

[0160] In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0161] (Formation of surface layer 30)

[0162] Next, a coating solution for the surface layer (coating solution for the surface layer) containing 100 parts by mass of acrylic resin (Seiko PMC Corporation, product name: Hi-Loss X PE-2273), 33 parts by mass of kaolin (shape: plate-like, particle size: 1 μm, Imerys Minerals Japan, product name: Astracoat), and 198 parts by mass of water was applied at a coating amount of 20 g / m using the air knife of the papermaking machine. 2 The acrylic resin and kaolin were applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a dry coating amount of 4.0 g / m2. 2 Thereafter, the paper was subjected to a calendar treatment so that the thickness of the paper became 60 μm, and an greaseproof paper (sample) was obtained.

[0163] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was imaged using a scanning white light interference microscope under the same conditions as in Example 1, but no protrusions were observed.

[0164] <Comparative Example 4>

[0165] (Preparation of Paper Base Material 10)

[0166] In the same manner as in Example 1, a paper base 10 was obtained.

[0167] (Formation of intermediate layers 20, 40)

[0168] In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0169] (Formation of surface layer 30)

[0170] Next, a coating solution for the surface layer (coating solution for the surface layer) containing 100 parts by mass of acrylic resin (Seiko PMC Corporation, product name: Hi-Loss X-PE-2273), 33 parts by mass of calcium carbonate (shape: columnar, median diameter: 0.2 μm, Okutama Kogyo Co., Ltd., product name: Tama Pearl TP-123), and 198 parts by mass of water was applied at a coating amount of 20 g / m using the air knife of the papermaking machine. 2 The resulting mixture was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a coating amount of 4.0 g / m2. The solvent was then dried to form the surface layer 30. The total dry adhesion amount of the acrylic resin and calcium carbonate was 4.0 g / m2. 2 Thereafter, the paper was subjected to a calendar treatment so that the thickness of the paper became 60 μm, and an greaseproof paper (sample) was obtained.

[0171] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was imaged using a scanning white light interference microscope under the same conditions as in Example 1, and the presence of protrusions was confirmed, but the number of protrusions was 10, and the protrusion radius was 8 μm.

[0172] <Comparative Example 5>

[0173] (Preparation of Paper Base Material 10)

[0174] In the same manner as in Example 1, a paper base 10 was obtained.

[0175] (Formation of intermediate layers 20, 40)

[0176] In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0177] (Formation of surface layer 30)

[0178] Next, a coating solution for the surface layer (coating solution for the surface layer) containing 100 parts by mass of acrylic resin (manufactured by Seiko PMC Corporation, product name: Hi-Loss X-PE-2273), 33 parts by mass of talc (manufactured by Kami-Talc Corporation, product name: KA-7), and 198 parts by mass of water was applied at a coating amount of 20 g / m2 using the air knife of the papermaking machine. 2 The acrylic resin and talc were applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a dry coating amount of 4.0 g / m2. 2 Thereafter, the paper was subjected to a calendar treatment so that the thickness of the paper became 60 μm, and an greaseproof paper (sample) was obtained.

[0179] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was imaged using a scanning white light interference microscope under the same conditions as in Example 1, and the presence of protrusions was confirmed, with the number of protrusions being 15 and the protrusion radius being 13 μm.

[0180] <Comparative Example 6>

[0181] (Preparation of Paper Base Material 10)

[0182] In the same manner as in Example 1, a paper base 10 was obtained.

[0183] (Formation of intermediate layers 20, 40)

[0184] In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0185] (Formation of surface layer 30)

[0186] Next, 100 parts by mass of acrylic resin (Seiko PMC, product name: Hi-Los X-PE-2273), 300 parts by mass of starch particles (ungelatinized rice starch particles, Matsutani Chemical Industry, product name: Matsutani Kikyo), and 600 parts by mass of water were mixed in the air knife of the papermaking machine while maintaining a temperature below the gelatinization temperature, to prepare a coating liquid for the surface layer (coating liquid for the surface layer) containing these. Then, this coating liquid for the surface layer was applied at a coating amount of 20 g / m while maintaining a temperature below the gelatinization temperature. 2 The resulting mixture was applied to one side of the intermediate layer 20 of the paper substrate 10 so that the solvent was dried to form the surface layer 30. The total dry adhesion amount of the acrylic resin and rice starch particles was 4.0 g / m 2 Thereafter, the paper was subjected to a calendar treatment so that the thickness of the paper became 60 μm, and an greaseproof paper (sample) was obtained.

[0187] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was imaged using a scanning white light interference microscope under the same conditions as in Example 1, and the presence of protrusions was confirmed, with the number of protrusions being 501 and the protrusion radius being 5 μm.

[0188] <Comparative Example 7>

[0189] (Preparation of Paper Base Material 10)

[0190] In the same manner as in Example 1, a paper base 10 was obtained.

[0191] (Formation of intermediate layers 20, 40)

[0192] In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0193] (Formation of surface layer 30)

[0194] Next, 100 parts by mass of polyacrylamide resin (manufactured by Arakawa Chemical Industries, product name: Polymaron 305A), 33 parts by mass of starch particles (ungelatinized rice starch particles, manufactured by Matsutani Chemical Industries, product name: Matsutani Kikyo), and 198 parts by mass of water were mixed using an air knife in a papermaking machine while maintaining a temperature below the gelatinization temperature, to prepare a coating liquid for the surface layer (coating liquid for the surface layer) containing these. Then, this coating liquid for the surface layer was applied at a coating amount of 20 g / m while maintaining a temperature below the gelatinization temperature. 2 The resulting mixture was applied to one side of the intermediate layer 20 of the paper base material 10 so that the solvent was dried to form the surface layer 30. The total dry adhesion amount of the polyacrylamide resin and starch particles was 4.0 g / m 2 Thereafter, the paper was subjected to a calendar treatment so that the thickness of the paper became 60 μm, and an greaseproof paper (sample) was obtained.

[0195] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was imaged using a scanning white light interference microscope under the same conditions as in Example 1, and the presence of protrusions was confirmed, but the number of protrusions was 8, and the protrusion radius was 5 μm.

[0196] <Comparative Example 8>

[0197] (Preparation of Paper Base Material 10)

[0198] In the same manner as in Example 1, a paper base 10 was obtained.

[0199] (Formation of intermediate layers 20, 40)

[0200] In the same manner as in Example 1, intermediate layers 20 and 40 were provided on both sides of the paper base material 10 .

[0201] (Formation of surface layer 30)

[0202] Next, a coating solution for the surface layer (coating solution for the surface layer) containing 100 parts by mass of acrylic resin (Seiko PMC, product name: Hi-Los X-PE-2273), 33 parts by mass of starch particles (rice starch particles, Matsutani Chemical Industry, product name: Matsutani Kikyo), and 198 parts by mass of water was prepared using the air knife of the papermaking machine. The starch particles were dispersed in water to prepare a suspension, which was then heated to or above the gelatinization temperature to be gelatinized (gelatinized rice starch). This coating solution for the surface layer was then applied at a coating amount of 20 g / m2. 2 The acrylic resin was applied to one side of the intermediate layer 20 of the paper base material 10 so as to obtain a coating amount of 4.0 g / m2. The solvent was then dried to form the surface layer 30. 2 Thereafter, the paper was subjected to a calendar treatment so that the thickness of the paper became 60 μm, and an greaseproof paper (sample) was obtained.

[0203] The kit value of the surface layer 30 was measured under the same measurement conditions as in Example 1. The surface state of the surface layer 30 was imaged using a scanning white light interference microscope under the same conditions as in Example 1, but no protrusions were observed.

[0204] <Evaluation method>

[0205] The physical properties of each of the obtained greaseproof papers were evaluated according to the methods described below.

[0206] (Surface condition) The surface state of the surface layer 30 was observed under three-wavelength fluorescent lamp (1000 lux) and visual confirmation conditions. When no streaks were visible to the naked eye, the sample was rated as "good". Otherwise, the sample was rated as "poor". In addition, in Comparative Example 8, fine uneven vertical streaks were observed on the surface in the flow direction, so the sample was rated as "poor".

[0207] (Practical oil resistance) The surface of each of the obtained grease-resistant papers was used as a measurement surface, and edible oil (manufactured by Nisshin Oillio Co., Ltd., product name "Canola Oil") was dropped onto the measurement surface. After 30 minutes at room temperature, the measurement surface was wiped and visually inspected for traces of edible oil that had penetrated the measurement surface. ○: After wiping the measurement surface, no traces of edible oil penetration (oil stains) were found on the measurement surface. ×: After wiping the measurement surface, traces of edible oil penetration (oil stains) were found on the measurement surface.

[0208] (Blocking resistance) The obtained oil-resistant papers were laminated so that the surface of the intermediate layer 40 was in contact with the surface layer 30 of the oil-resistant paper, and the surface layer 30 was subjected to a pressure of 10 kgf / cm under the conditions of 23° C. and 50% RH. 2 After pressing, the state of blocking was visually confirmed. ○: When lifting the paper, there was no resistance and it could be peeled off easily. ×: When the papers were lifted, the papers stuck together, resistance to peeling was felt, and an abnormal noise was generated.

[0209] The manufacturing conditions and evaluation results of each of the Examples and Comparative Examples are shown in Tables 1 and 2. In Table 1, "solid content equivalent" is the content of "particles" in the surface layer 30 in solid content equivalent, and "dry adhesion amount" is the sum of the dry adhesion amount of "resin" and the dry adhesion amount of "particles." As an example, Fig. 4 shows a photograph of the surface layer of Example 6 taken with a scanning white light interference microscope, and Fig. 5 shows a photograph of the surface layer of Comparative Example 3 taken with a scanning white light interference microscope.

[0210] [Table 1]

[0211] [Table 2]

[0212] From the above, it was confirmed that the present example at least provides an greaseproof paper having high enough oil resistance to withstand practical use and excellent blocking resistance. Furthermore, it was also confirmed that even a non-fluorine-based greaseproof paper that does not contain a fluorine-based resin, as in the present example, can provide such excellent effects, and further that such excellent effects can be obtained without blending inorganic fillers such as kaolin, calcium carbonate, talc, etc. [Explanation of symbols]

[0213] 1,2,3: Greaseproof paper 10:Paper base material 20,40: Middle class 30,50: Surface layer 31,51: Starch granules 32,52: (Meth)acrylic resin

Claims

1. The greaseproof paper includes a paper base material, an intermediate layer, and a surface layer, The intermediate layer is provided on at least one surface of the paper base material, the surface layer is provided on a surface of the intermediate layer opposite to a surface on which the paper base material is provided, The intermediate layer contains polyvinyl alcohol, the surface layer contains a (meth)acrylic resin and ungelatinized starch particles, The kit value measured in accordance with JAPAN TAPPI Paper and Pulp Testing Method No. 41:2000 using the surface of the surface layer as a measurement surface is 6 or more; In a 360 μm×270 μm photograph of the surface of the surface layer taken with a scanning white light interference microscope at a magnification of 50 times, protrusions due to the starch particles are present, In the photograph, the protrusion shape has a height difference of 5 μm or more in the surface layer and a radius of a minimum circumscribed circle in a top view of 5 to 30 μm; In the photograph, there are 50 to 320 protrusion shapes. Greaseproof paper.

2. The surface layer contains 10 to 200 parts by mass of the starch particles relative to 100 parts by mass of the (meth)acrylic resin.

2. The greaseproof paper according to claim 1.

3. The dry adhesion amount of the polyvinyl alcohol in the intermediate layer is 0.2 to 0.6 g / m ２ That is, 3. The greaseproof paper according to claim 1 or 2.

4. The intermediate layer is provided on both sides of the paper base material. The greaseproof paper according to any one of claims 1 to 3.

5. The intermediate layer is provided on both sides of the paper base material, The total dry adhesion amount of the polyvinyl alcohol in the intermediate layer on both sides is 0.4 to 1.2 g / m ２ That is, The greaseproof paper according to claim 4.

6. The surface layer is provided on both sides of the paper base material via the intermediate layer. The greaseproof paper according to claim 4 or 5.

7. The dry adhesion amount of the (meth)acrylic resin in the surface layer is 1.2 to 3.6 g / m per one side of the paper base material. ２ That is, The greaseproof paper according to any one of claims 1 to 6.

8. The content of the starch particles in the surface layer is 5 to 70% by mass in terms of solid content. The greaseproof paper according to any one of claims 1 to 7.

9. Food packaging paper used as a material for packaging food, A food packaging paper comprising the greaseproof paper according to any one of claims 1 to 8.

10. A packaging material comprising the greaseproof paper according to any one of claims 1 to 8.

11. The greaseproof paper according to any one of claims 1 to 8 is included, A packaging bag, wherein the surface layer is arranged on the side that comes into contact with the packaged item.

12. A step of applying a coating liquid containing polyvinyl alcohol onto a surface of a paper substrate to form an intermediate layer; A step of applying a coating liquid containing a (meth)acrylic resin and ungelatinized starch particles onto a surface of the intermediate layer to form a surface layer; Including, A method for producing greaseproof paper according to any one of claims 1 to 8.

Images