JP2015193944A - Oil resistant paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide oil resistant paper in which coating stability and oil resistance are made consistent, and oil stains caused by transparency, blackening or the like is inconspicuous even in the case the penetration of oil occurs.SOLUTION: Provided is oil resistant paper obtained by providing one side of a base material with at least one or more non-fluorine-based oil resistant layers, in which an oil resistant agent used in at least one layer of the oil resistant layers is made of a starch-based or polyvinyl alcohol-based water soluble resin, and the amount of the titanium oxide incorporated into the base material is 20 to 40 mass%.

Description

  The present invention relates to oil-resistant paper and a method for producing oil-resistant paper. Specifically, the present invention provides an oil-resistant paper having an oil-resistant layer capable of suppressing the penetration of oil into the base material and suppressing transparency and blackening even when the oil penetrates the base material. The present invention relates to a method for producing oil-resistant paper.

Paper or paperboard is widely used for packaging materials such as food. In particular, oil-resistant paper and paperboard are used for food wrapping paper that contains a large amount of oil and fat components derived from animal and vegetable oils such as chocolate, pizza, and donuts. Has been devised. When oil and fat components contained in food penetrate into the wrapping paper, the oil penetrates to the surface of the paper, creating an oil stain on the surface and impairing the appearance, and the printed part becomes black due to the oil stain and characters cannot be read. There is a possibility that the suitability of OCR such as a code and a QR code (registered trademark) may be lowered. In addition, there are problems such as transfer of oil to clothes and contamination. For this reason, paper and paperboard which gave oil resistance to the part which touches food are used for the packaging paper of the foodstuff containing fats and oils components.

Oil resistant paper contains an oil resistant agent in order to exhibit oil resistance, and conventionally, a fluororesin-based oil resistant agent has been used as the oil resistant agent (for example, Patent Document 1). For example, oil-resistant paper in which a fluororesin-based oilproofing agent is applied to the surface of paper or paperboard to provide an oilproof layer, and oil-resistant paper in which a fluororesin-based oilproofing agent layer is provided between paper layers are known. However, it has been confirmed that when oil-resistant paper using a fluororesin-based oil-resistant agent is heated at a cooking temperature of 100 to 180 ° C., components that are likely to remain for a long time such as C8 to C10 fluorine-based alcohol compounds are generated. . Also, when oil-resistant paper using these fluororesin-based oil-proofing agents is incinerated after use, fluorine compounds such as perfluorooctanoic acid and perfluorosulfonic acid are generated, and there is a concern that it may adversely affect health or the environment. ing.

In order to solve these problems, oil-resistant paper using a polyvinyl alcohol-based resin as a non-fluorinated oil-resistant agent has been developed (for example, Patent Documents 2 and 3). Since the polyvinyl alcohol-based resin forms a strong hydrophilic film, it can prevent oil permeation and can exhibit excellent oil resistance.
Fluorine-based oil resistant agents have exhibited oil resistance by utilizing the oil repellency derived from fluorine, whereas polyvinyl alcohol resins exhibit oil resistance due to the barrier effect of the coating layer film.
Oil-resistant paper containing a non-fluorine-based oil resistant agent does not generate a fluorine compound or the like when heated, and thus has an advantage of high safety and low environmental burden.
However, when such a non-fluorinated oil resistance agent is applied with a bar coater or a rod metering size press coater, coating defects such as foaming of the coating liquid and generation of bubbles in the oil resistant layer may occur. . Furthermore, when foaming is severe, coating unevenness occurs, and the oil resistance of the oil resistant layer may be reduced.

In addition, an oil-resistant decorative printing sheet has been proposed in which an ink layer having a color tone and a pattern is appropriately provided on at least one surface of a thin paper impregnated with an oil-resistant resin (for example, Patent Document 4). However, in such an oil-resistant decorative printing sheet, there is a limit in preventing impregnation of oil and fat adhering to the sheet, and it is difficult to prevent physical damage to the sheet.

JP 2009-120996 A JP 2011-26745 A JP 2011-185812 A JP-A-8-118554

  As described above, foaming during coating can be suppressed to some extent by adding an antifoaming agent or the like to the coating liquid containing a non-fluorinated oilproofing agent. However, when the antifoaming agent itself has a strong lipophilicity, the oil penetrates and there is a problem that the oil resistant layer cannot sufficiently exhibit the oil resistance. That is, in the coating liquid containing the conventional non-fluorine-based oil resistant agent, coating stability and oil resistance are not compatible, and further improvement has been demanded.

  In addition, oil-resistant paper using conventional oil-proofing agents can ensure oil resistance against contact with oil for a short time. May penetrate. When the oil penetrates into the inside of the base material, the base material becomes transparent, and thereafter, the portion becomes noticeable black.

Therefore, in order to solve the problems of the prior art, the present inventors suppress the penetration of oil into the base material, and even when the penetration occurs, oil spots such as transparency and blackening are not generated. A study was carried out with the aim of providing oil-resistant paper that is inconspicuous.

As a result of intensive studies to solve the above problems, the present inventors have included a specific amount of titanium oxide in a base material having an oil-resistant layer, and the oil-resistant layer has water-soluble starch or polyvinyl alcohol. Resin is used. As a result, it is possible to produce oil-resistant paper that suppresses oil penetration into the base material and that makes oil stains less noticeable even when the oil has soaked in the base material due to contact with the oil for a long time. As a result, the present invention has been completed.
Specifically, the present invention has the following configuration.

[1] An oil-resistant paper provided with at least one non-fluorine-based oil-resistant layer on one side of a substrate, wherein the oil-resistant agent used in at least one of the oil-resistant layers is a starch-based or polyvinyl alcohol-based An oil-resistant paper which is a water-soluble resin and has an amount of titanium oxide contained in the substrate of 20 to 40% by mass.
[2] The oil-resistant paper according to [1], wherein the water-soluble resin is ethylene-modified polyvinyl alcohol or carboxy group-modified polyvinyl alcohol.
[3] The oil-resistant paper according to [1] or [2], wherein a concealing layer containing titanium oxide is provided on the surface opposite to the surface provided with the oil-resistant layer of the substrate.

  According to the present invention, oil resistance to oil and concealment that does not make oil spots noticeable when the oil penetrates the base material are provided. Therefore, when used for printed plywood, the oil and fat component adheres from the outside, and even when immersed in a base material, it is preferably used as a building material paper or the like that does not become transparent or blackened and does not deteriorate in design.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Oil resistant paper)
The present invention is an oil-resistant paper provided with at least one non-fluorinated oil-resistant layer on one side of a substrate, and the oil-resistant agent used in at least one of the oil-resistant layers is a starch-based or polyvinyl alcohol-based It is a water-soluble resin, and the amount of titanium oxide contained in the substrate is 20 to 40% by mass.
The oil resistant paper of the present invention is excellent in oil resistance and contains 20 to 40% by mass of titanium oxide in the base material. Therefore, even when the oil penetrates into the base material, the base material is transparent due to the oil soaking. Can be made inconspicuous. In addition, since the oil-resistant paper of the present invention uses a non-fluorine-based oil-resistant agent, even when the oil-resistant paper is heated and incinerated, no fluorine compound is generated, and the safety is high and the burden on the environment is high. It has the advantage of being less.
Accordingly, the oil-resistant paper of the present invention can be used as a building material (such as a decorative material paper) in a place where oil and fat components and the like easily adhere to a kitchen or factory.

  In the present invention, the non-fluorinated oil-resistant layer means that the content of the fluorine-based oil resistant agent is 5% by mass or less, preferably 1% by mass or less, more preferably 0% by mass with respect to the oil-resistant layer. is there. The non-fluorinated oil-resistant layer preferably uses a non-fluorinated oil-resistant agent as the oil-resistant agent, and preferably contains a starch-based or polyvinyl alcohol-based water-soluble resin as described later as the non-fluorinated oil-resistant agent.

(Oil resistant layer)
In the present invention, the oil resistant layer contains a starch-based or polyvinyl alcohol-based water-soluble resin.
As starch used in the present invention, in addition to ordinary starch, grafted starch, hydroxyethylated starch, hydroxypropylated starch, carboxymethylated starch, cationized starch, acetylated starch, phosphate starch, phosphate distarch , Glycerol distarch, white dextrin, yellow dextrin, British gum, maltodextrin, oxidized starch, acid-treated starch, pregelatinized starch, etc. etherified starch, esterified starch, crosslinked starch, roasted starch, enzyme-modified starch Starch can be used. In addition, granulated granular starch, porous oil-absorbing starch, and the like can be suitably used.

The starch used in the present invention may be hydrophobized. Here, as the hydrophobization treatment of starch, starch is intimately contacted with an aqueous solution of organosilane in the presence of alkali aluminate or alkali hydroxide, a method of derivatization with silicone or an alkenyl compound, and octenyl succinic anhydride in an aqueous system. , Starch and organic acid anhydrides such as dozecenyl succinic anhydride, starch, copolymerization of hydrophobic monomers such as acrylonitrile and hydrophobic unsaturated acid monomers, starch alkyl succinate, Examples thereof include a method using a mixture containing starch and a styrene-acrylic polymer having a C8-24-alkyl methacrylate group disclosed in Japanese Patent Application Publication No. 2006-37316. In particular, a method using a mixture containing starch and a styrene-acrylic polymer having a C8-24-alkyl methacrylate group is preferable.

Examples of the raw material of starch used in the present invention include corn starch (corn starch), waxy corn starch, potato starch, tapioca starch, wheat starch, sweet potato starch, rice starch and the like. These starches can be used in combination of two or more.

Examples of the polyvinyl alcohol resin used in the present invention include unmodified fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol and modified polyvinyl alcohol. Examples of the modified polyvinyl alcohol include ethylene modified polyvinyl alcohol and carboxy group modified polyvinyl alcohol. And silicon modified polyvinyl alcohol, acetoacetyl group modified polyvinyl alcohol, diacetone group modified polyvinyl alcohol and the like. Two or more of these polyvinyl alcohol resins can be used in combination.
Among them, ethylene-modified polyvinyl alcohol (for example, trade name: “EXEVAL” series, manufactured by Kuraray Co., Ltd.) and carboxy group-modified polyvinyl alcohol (for example, trade name: “GOHSENAL” series, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Is preferable because of its excellent oil resistance.

In particular, carboxy group-modified polyvinyl alcohol can impart high oil resistance to oil-resistant paper. Further, by using carboxy group-modified polyvinyl alcohol in the oil resistant layer, foaming of the coating liquid can be suppressed, and such foaming suppression effect can be achieved without adding an antifoaming agent to the coating liquid. Can be obtained. Furthermore, the carboxy group-modified polyvinyl alcohol can suppress the thickening of the coating solution. Thereby, the coating liquid excellent in coating suitability can be obtained, and the state of the coated surface of the oil resistant layer can be improved.

Moreover, starch-type resin and polyvinyl alcohol-type resin should add a polyoxyethylene (3-10 mol addition) polyoxypropylene (25-35 mol addition) block polymer before temperature rising or during temperature rising at the time of melt | dissolution. Therefore, foaming at the time of dissolving the starch-based resin and the polyvinyl alcohol-based resin can be suppressed, and the defoaming effect is not impaired by heating, which is preferable. Of course, a starch-based resin or a polyvinyl alcohol-based resin solution after dissolution can be added to the paint to obtain a foam suppression effect during coating.

The content of the starch-based resin or the polyvinyl alcohol-based resin is preferably 0.1 to 80% by mass with respect to the total solid content mass of the oil-resistant layer (total solid content mass of the coating liquid). It is more preferable that it is mass%, and it is further more preferable that it is 3-50 mass%.
By making the content rate of starch-type resin or polyvinyl alcohol-type resin into the said range, the oil resistance of an oil-resistant layer can fully be improved. Furthermore, foaming of the coating liquid for forming the oil resistant layer can be sufficiently suppressed, and the occurrence of coating defects can be suppressed.

The oil-proofing agent used in at least one of the oil-resistant layers of the present invention is a starch-based resin or a polyvinyl alcohol-based resin. And pigments can be used in combination.

As the water-insoluble resin contained in the oil-resistant layer, the glass transition temperature of the water-insoluble resin is preferably 50 ° C. or lower. Examples of water-insoluble resins include acrylic resins, polyester resins, polyurethane resins, styrene-butadiene copolymer resins, styrene-acrylic resins, ethylene-vinyl acetate resins, acrylonitrile-butadiene resins, polyethylene resins, Polypropylene resin, carboxymethyl cellulose resin, polyethylene terephthalate resin, polyamide resin, vinyl chloride resin, vinylidene chloride resin, silicone resin, mixture of acrylic resin and wax, mixture of styrene-acrylic resin and wax, etc. Can be mentioned. Among these, it is preferable to use a styrene-butadiene copolymer resin or an acrylic resin. Thus, the outstanding water resistance can be exhibited by containing a water-insoluble resin in an oil-resistant layer.

Examples of the acrylic resin include copolymer emulsions such as acrylic polymers and acrylic-styrene copolymers, and emulsions such as self-crosslinking acrylic copolymer emulsions. Specifically, styrene and styrene derivatives, acrylic acid (methacrylic acid) and alkyl acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate, and alkyl methacrylates such as methyl methacrylate were copolymerized. Examples thereof include acrylic copolymers, copolymer emulsions of acrylamide and acrylic acid (methacrylic acid), and copolymer emulsions of acrylonitrile and acrylic acid (methacrylic acid). The glass transition temperature of the acrylic resin is preferably 50 ° C. or lower, may be 20 ° C. or lower, and may be 0 ° C. or lower. Thus, by setting the glass transition temperature to 50 ° C. or lower, the oil resistant layer can exhibit high film forming ability and excellent oil resistance.

The mass ratio of the starch resin or polyvinyl alcohol resin contained in the oil-resistant layer to the water-insoluble resin is preferably 1: 9 to 9: 1, and more preferably 2: 8 to 8: 2. . By setting the mass ratio of the starch-based resin or polyvinyl alcohol-based resin and the water-insoluble resin within the above range, an oil-resistant paper excellent in both oil resistance and water resistance can be obtained.

As the pigment contained in the oil-resistant layer, various pigments such as inorganic pigments and organic pigments can be used. Specific examples of inorganic pigments include kaolins, structural kaolins, delaminated kaolins, calcined kaolins, synthetic mica, heavy calcium carbonate, light calcium carbonate, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, Examples thereof include minerals such as alumina, aluminum hydroxide, magnesium carbonate, magnesium oxide, silica, magnesium aluminosilicate, calcium silicate, white carbon, bentonite, zeolite, sericite, and smectite. Of these, kaolin is preferably used since it exhibits excellent oil resistance and water resistance. Specific examples of organic pigments include polydienes such as polyisoprene, polyneoprene and polybutadiene, polyalkenes such as polybutene, polyisobutylene and polypropylene, vinyl acetate, styrene, (meth) acrylic acid and alkyl (meth) acrylate. Polymers and copolymers of vinyl monomers such as esters, (meth) acrylamide, and methyl vinyl ether, polyurethane resins, polyester resins, polyamide resins, urea resins, melamine resins, benzoguanamine resins, etc. Mold, hollow type, or through-hole type particle. These pigments may be used alone or in combination of two or more.

The content of the pigment is preferably 20 to 70% by mass, more preferably 30 to 70% by mass, based on the total solid content of the oil-resistant layer (total solid content of the coating liquid). More preferably, it is 40-65 mass%. By setting the content of the pigment within the above range, a paint having good coating suitability can be produced.

In addition, it is good also as adding various auxiliary agents normally used, such as a dispersing agent, a thickener, a water retention agent, an antifoamer, and a coloring agent, to an oil-resistant layer coating liquid as needed. The content of these auxiliaries is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 1% by mass or less, based on the total solid mass of the oil-resistant layer. preferable.

In the present invention, it is preferable to control the viscosity of the oil-resistant layer coating solution in order to ensure coating suitability in a bar coater, blade coater, or rod metering size press coater. For this reason, it is preferable that the molecular weight (weight average molecular weight) of water-soluble resin shall be 50,000-2 million.
The molecular weight of the water-soluble resin can be appropriately adjusted by controlling the reaction temperature, reaction time, acid value and the like during polymerization. Furthermore, you may use a well-known chain transfer agent. Examples of such chain transfer agents include butyl mercaptan, dodecyl mercaptan, octyl thioglycolate, isopropyl alcohol, methanol, carbon tetrachloride and the like. The usage-amount is 0.001-2.0 mass parts with respect to 100 mass parts of monomer components, Preferably it is 0.05-1.0 mass part.

(Base material)
Examples of the base material used in the oil-resistant paper of the present invention include high-quality paper, medium-quality paper, finely coated paper, coated paper, glossy paper, bleached or unbleached kraft paper (acidic paper or neutral paper), Alternatively, paperboard, white paperboard, or the like used for cardboard, building materials, white balls, chip balls, or the like can be used.

As the pulp constituting the substrate, any of those usually used for papermaking can be used. For example, chemical pulp such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood bleached sulfite pulp (LBSP), softwood bleached sulfite pulp (NBSP), stone grand pulp (GP), pressure stone Unbleached, semi-bleached or bleached pulp, sulfite pulp, waste paper such as ground pulp (PGW), refiner ground pulp (RGP), chemiground pulp (CGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP) Pulp etc. can be used. In blending the pulp of the base material, it is preferable to blend a large amount of LBKP excellent in dimensional stability, and it is preferable to blend 60 to 100% by mass of 100% by mass of the total pulp.

The basis weight of the substrate that can be used in the present invention is preferably ²⁰ to 150 g / m ² . By setting the basis weight of the base material within the above range, the strength necessary for forming the oil-resistant layer can be maintained. When the basis weight of the base material exceeds 150 g / m ² , the base material is likely to buckle at the fold portion, so that the base material is cracked and the oil resistance of the fold tends to be lowered. In addition, the JAPAN TAPPI paper pulp test method No. The Oken air permeability measured according to 5-2: 2000 is not particularly limited, but is preferably 0 to 400 seconds.

Furthermore, in order to increase the air permeability of the base material, it is preferable that the Canadian standard freeness measured by pulsing the pulp to be used according to JIS P 8121-1995 is 300 ml or less. A more preferable range of beating degree is 80 to 250 ml. By setting the beating degree within the above range, the oil resistance of the entire oil resistant paper can be enhanced.

In addition, the pulp to be used has been described above using a beater such as a beater, a Jordan, a single disc refiner, a conical refiner, a cylindrical refiner, a deluxe refiner, a double disc refiner (DDR), a medium agitating mill, a vibration mill, or the like. It is adjusted to be beaten. The beating conditions are not particularly limited, but the shape of the refiner blades, rotation speed, pulp concentration, pulp fiber length, pulp roughness, etc. will affect the physical properties of the pulp after beating, so the desired beating degree can be obtained. The beating conditions are selected as appropriate.

In order to enhance the air permeability of the base material, it is preferred that the density of the base material and 0.8~1.2g / cm ^3, and more preferably to 0.85~1.1g / cm ³ . Specific methods for increasing the density of the substrate include pressing in the wet paper state when making the substrate, using a machine calendar, soft nip calender, gloss calendar after drying, or using a super calendar after making the substrate. To do. Among them, the pressure treatment used at the time of wet paper is preferable because the pressure can be applied in a state where the substrate moisture is high, and the density can be increased efficiently even compared with the calendar treatment after drying. .

The thickness of the substrate is preferably 30 μm or more, and more preferably 40 μm or more. Further, the thickness of the substrate is preferably 500 μm or less, and more preferably 300 μm or less. By setting the thickness of the substrate within the above range, it is possible to have an appropriate strength and to improve the coating suitability of the oil resistant layer.

The substrate may further contain an additive. As additives, sizing agents represented by rosin, alkyl ketene dimer, alkenyl succinic acid, etc., fixing agents represented by sulfuric acid bands, cationic polymer electrolytes, clay, talc, calcium carbonate, calcined kaolin, aluminum oxide, Aluminum hydroxide, titanium oxide, amorphous silica, fillers represented by urea-formalin resin particles, polyacrylamide polymers, paper strength enhancers represented by starch, melamine resins, urea resins, polyamide-polyamines Examples thereof include wet paper strength enhancers represented by epichlorohydrin resins and the like, as well as various auxiliary agents such as filter agents, dyes for color tone adjustment such as bluing, and fluorescent dyes.

In this invention, 20-40 mass% of titanium oxide is contained as a filler in a base material. As a result, even when the oil penetrates into the inside of the base material, it is possible to make the base material transparent or blackened due to the oil soaked portion or the like.

Incidentally, when the content of titanium oxide is less than 20% by mass, the effect of suppressing the transparency caused by the oil is lowered, and blackening tends to occur. On the other hand, when the content of titanium oxide exceeds 40% by mass, the strength of the oil-resistant paper is lowered, and there is a possibility that a piece of paper is generated during the production of the oil-resistant paper and the production efficiency is lowered.

(Hidden layer)
In the present invention, it is preferable to provide a concealing layer containing titanium oxide on the surface opposite to the surface provided with the oil resistant layer of the base material. As a result, even when the oil penetrates into the inside of the base material and becomes transparent, and then the portion is blackened, it is possible to make the base material transparent and blackened inconspicuously.
The concealing layer contains titanium oxide (anatase type, rutile type, antimony-doped titanium oxide, etc.) as a main component, and is formed of an aqueous or organic solvent-based paint containing these. A known pigment is used as a white pigment other than titanium oxide contained in the masking layer. Examples of inorganic pigments include calcium carbonate, silica, zinc oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium and silica inorganic fine powders, etc. Examples of organic pigments include hollow fine particles such as organic fine powders such as urea-formalin resin, styrene-methacrylic copolymer, and polystyrene resin. These white pigments can be used alone or in admixture of two or more. Among these, since the concealing effect is excellent, hollow fine particles made of titanium oxide or a thermoplastic resin are preferably used.

The coating material for forming the concealing layer contains such titanium oxide as a main component, and is further prepared by blending an additive or a paint adjusting agent if desired. Examples of the adhesive and solvent include the following.

Adhesives include water-soluble polymers such as polyvinyl alcohol, casein, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, styrene-maleic anhydride copolymer, acrylonitrile-butadiene copolymer, methyl acrylate. -Butadiene copolymer, ethylene-maleic anhydride copolymer, styrene-butadiene copolymer, latex of water-insoluble resin such as acrylic resin, vinyl acetate resin, or emulsion, polyurethane resin, vinyl chloride resin, A water-insoluble resin such as a vinyl-vinyl acetate copolymer or a polyester resin can be used. Among these, since water resistance, abrasion resistance, flexibility, etc. are good, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, methyl acrylate-butadiene copolymer, vinyl chloride resin, polyurethane resin, etc. Emulsion water-insoluble resins are preferred.

In addition, as the resin used in the present invention, a resin soluble in an organic solvent such as toluene, xylene, isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, mineral spirit, or solvent naphtha can be used. For example, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, polyurethane resin, saturated polyester resin, polyester polyurethane resin, epoxy resin, phenoxy resin, nitrocellulose resin, melamine resin, chlorinated polyethylene resin, etc. Is mentioned.

The coating material for forming the concealment layer as described above is a surface opposite to the surface provided with the oil-resistant layer of the base material using a bar coater, reverse roll coater, roll coater, blade coater, rod metering size press coater, or gravure coater. And dried, thereby forming a concealing layer. In addition, the masking layer can be provided by printing. The coating amount of the concealing layer is preferably 1 to ²⁰ g / m ² , and more preferably ² to 15 g / m ² . When it is less than 1 g / m ^2, it is difficult to uniformly coat the concealing layer, and when it is greater than 20 g / m ² , the effect is hardly improved.

(Oil-resistant paper manufacturing method)
<Manufacturing method of substrate>
The base material can be obtained by making paper with various paper machines by a conventional method, forming wet paper, and then drying. The base material preferably contains starch, polyvinyl alcohol, gelatin, filler, etc., if necessary, and is preferably manufactured through a conventional process such as a smoothing process using a surface size press machine calender or the like. .
Examples of the paper machine used in the present invention include a long net paper machine having an air cushion head box or a hydraulic head box, a twin wire paper machine, an on-top type twin wire paper machine, and a Yankee paper machine.

<Oil-resistant layer manufacturing method>
The oil resistant layer is formed by applying a coating solution containing a starch-based or polyvinyl alcohol-based water-soluble resin on at least one surface of the substrate. As a method for coating the oil-resistant layer, generally known coating apparatuses can be used. For example, blade coaters, air knife coaters, roll coaters, reverse roll coaters, bar coaters, curtain coaters, slot die coaters, gravure coaters, channels A plex coater, a brush coater, a slide bead coater, a two-roll or rod metering type size press coater, a bill rod metering size press coater, a short dwell coater, a gate roll coater, a nip coater using a calendar, and the like are appropriately used. Among them, in order to increase production efficiency, it is preferable to use a bar coater, a blade coater, or a rod metering size press coater, and it is more preferable to use a rod metering size press coater.

The coating amount of the oil layer is preferably in the range of 0.5~20.0g / ^{m 2,} and more preferably in the range of 1.0~18.0g / ^{m 2.} By setting the coating amount of the oil resistant layer within the above range, an oil resistant layer capable of exhibiting sufficient oil resistance can be obtained.
In the present invention, only one layer of the oil resistant layer may be provided on at least one side of the base material, but a plurality of layers may be provided on at least one side of the base material. When the same coating amount is applied, the oil resistance that is superior to the single-layer structure tends to be more easily obtained when the multi-layer structure is used. When the oil-resistant layer has a multi-layer structure, the number of layers is preferably 2 to 5 layers, and more preferably 2 to 4 layers. In the case of a multi-layer configuration, each layer may have the same configuration (composition) or may be different. In addition, when there are a plurality of oil-resistant layers, the total coating amount is preferably within the above range.

After applying the oil resistant agent to one side of the substrate, a step of drying the oil resistant agent is provided.
Moreover, in this invention, after oil-resistant layer formation, a smoothing process can be performed as needed. The smoothing process is performed on-machine or off-machine using a smoothing processing apparatus such as a normal super calendar, gloss calendar, or soft calendar.

<Manufacturing method of concealment layer>
The concealing layer is formed by applying a concealing layer-forming coating material containing titanium oxide to the surface opposite to the surface provided with the oil-resistant layer of the base material. As the coating method for the masking layer, a generally known coating device similar to the method for producing the oil-resistant layer can be used. In addition to this, the masking layer can be provided by printing.
The coating amount of the concealing layer is preferably 1 to ²⁰ g / m ² , and more preferably ² to 15 g / m ² . After the coating material for forming the concealing layer is applied, a step of drying the paint is provided.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

<Adjustment of oil-resistant layer coating solution>
(1) Preparation of oil-resistant layer coating solution-1 To 90.5 parts by mass of water, 9.5 parts by mass of carboxy group-modified polyvinyl alcohol (trade name: “GOHSENAL T330” manufactured by Nippon Synthetic Chemical Co., Ltd.) as a water-soluble resin, poly Add 0.009 parts by mass of oxyethylene (5 mol addition) polyoxypropylene (30 mol addition) block primer (trade name: “Pepol B-181”, manufactured by Toho Chemical Co., Ltd.), and rise to 95 ° C. with stirring. After maintaining the temperature for 1 hour, it was cooled to room temperature to obtain an oil-resistant layer coating solution-1 which was a 9% concentration carboxy group-modified polyvinyl alcohol aqueous solution.

(2) Preparation of Oil Resistant Layer Coating Solution-2 Carboxy group-modified polyvinyl alcohol (trade name: “GOHSENAL T330” manufactured by Nippon Synthetic Chemical Co., Ltd.) and ethylene-modified polyvinyl alcohol (trade name: “EXVAL HR3010”) ( Except for changing to Kuraray Co., Ltd.), the same operation as oil-resistant layer coating solution-1 was performed to obtain oil-resistant layer coating solution-2.

(3) Preparation of Oil Resistant Layer Coating Solution-3 Carboxy group-modified polyvinyl alcohol (trade name: “GOHSENAL T330” manufactured by Nippon Synthetic Chemical Co., Ltd.) as a water-soluble resin and oxidized starch (trade name: “ACE A”, Oji Cornstarch) Except having changed to (made by Corporation | KK), operation similar to oil-resistant layer coating liquid-1 was performed, and oil-resistant layer coating liquid-3 was obtained.

(4) Preparation of oil-resistant layer coating liquid-4 As a water-soluble resin, 30.0 parts by mass of a 10% aqueous solution of carboxy group-modified polyvinyl alcohol (trade name: “GOHSENAL T330” manufactured by Nippon Synthetic Chemical Co., Ltd.), as a water-insoluble resin 20.0 parts by mass of a 48% aqueous dispersion of styrene-butadiene copolymer latex (trade name: “X300B”, manufactured by JSR, glass transition temperature: −19 ° C.), kaolin (trade name: “Ultra White 90”, 40.0 parts by mass of a 70% aqueous dispersion of BASF) and water were mixed and stirred to obtain an oil-resistant layer coating solution-4 having a coating solution solid content concentration of 20% by mass.

(5) Preparation of oil-resistant layer coating solution-5 As a water-soluble resin, carboxy group-modified polyvinyl alcohol (trade name: “GOHSENAL T330” manufactured by Nippon Synthetic Chemical Co., Ltd.) and ethylene-modified polyvinyl alcohol (trade name: “EXVAL HR3010” ( Except having changed to Kuraray Co., Ltd.), operation similar to oil-resistant layer coating liquid-4 was performed, and oil-resistant layer coating liquid-5 with a coating liquid solid content concentration of 20 mass% was obtained.

(6) Preparation of Oil Resistant Layer Coating Liquid-6 As a water-soluble resin, carboxy group-modified polyvinyl alcohol (trade name: “GOHSENAL T330” manufactured by Nippon Synthetic Chemical Co., Ltd.) and oxidized starch (trade name: “ACE A”, Oji Cornstarch Co., Ltd.) Except having changed to (made by Co., Ltd.), operation similar to oil-resistant layer coating liquid-4 was performed, and oil-resistant layer coating liquid-6 with a coating liquid solid content concentration of 20 mass% was obtained.

<Creation of base material>
(1) Preparation of base material-1 Ru-type titanium dioxide (CR-58, manufactured by Ishihara Sangyo Co., Ltd.) with 72.76% by mass of pulp mixed with 9: 1 L-BKP and N-BKP and beaten in 350 ml CSF freeness 1% by mass of polyamide epichlorohydrin wet paper strength enhancer WS-4052 (manufactured by Seiko PMC), 1.2% by mass of polyamine yield improver Kathiofast VFH (manufactured by Seiko PMC), yellow dye 0.04% by mass of Kayafect Yellow AW (manufactured by Nippon Kayaku Co., Ltd.) was added and hand-made with a square-type hand-making machine to prepare a base material-1 having a basis weight of about 80 g / m ² . . The base material-1 which contains 22 mass% of titanium oxide in a base material was obtained.

(2) Preparation of base material-2 L-BKP and N-BKP were mixed at a ratio of 9: 1 and pulp beaten in 350 ml CSF freeness to 57.76% by mass, rutile titanium dioxide (CR-58, Ishihara as titanium oxide) The same operation as that of the base material-1 was carried out except that (made by industry) was changed to 40% by mass to obtain a base material-2 containing 38% titanium oxide in the base material.

(3) Preparation of base material-3 The pulp which mix | blended L-BKP and N-BKP by 9: 1, and was beaten to freeness 350mlCSF was made into 42.76 mass%, rutile type titanium dioxide (CR-58, Ishihara as titanium oxide). The base material-3 containing 45% titanium oxide in the base material was prepared by performing the same operation as the base material-1 except that the product was changed to 55% by mass, respectively, but the strength was low and normal. Paper creation was not possible.

(4) Preparation of base material-4 The pulp which mix | blended L-BKP and N-BKP by 9: 1, and beaten to freeness 350mlCSF was made into 77.76 mass%, rutile type titanium dioxide (CR-58, Ishihara as titanium oxide). The same operation as that of the base material-1 was carried out except that (Made in Industry) was changed to 20% by mass to obtain a base material-4 containing 18% titanium oxide in the base material.

<Adjustment of back surface concealing layer coating solution>
(1) Preparation of back surface concealing layer coating solution-1 100 parts by mass of a 10% aqueous solution of completely saponified polyvinyl alcohol (trade name: “PVA117” manufactured by Kuraray Co., Ltd.) as a water-soluble resin, and rutile titanium dioxide (CR -58 Ishihara Sangyo Co., Ltd.) 50% aqueous dispersion (180 parts by mass) was added and mixed with water to obtain a back surface concealing layer coating liquid-1 having a coating liquid solid content concentration of 35 mass%.

<Example 1>
An oil-resistant paper-1 was obtained by applying 10 g / m ^{2 of the} oil-resistant layer coating solution-1 in an absolutely dry amount on the substrate-1 with a bar coater.

<Example 2>
Except having changed oil-resistant layer coating liquid-1 into oil-resistant layer coating liquid-2, operation similar to Example 1 was performed and oil-resistant paper-2 was obtained.

<Example 3>
Change the substrate -1 to the substrate -2 on the back surface of the base material -2 except that 10 g / m ² coated at absolute dry weight of the back surface concealing layer coating solution-1 by a bar coater Example 2 The same operation was performed to obtain oil-resistant paper-3.

<Example 4>
The same operation as in Example 1 was carried out except that the base material-1 was changed to the base material-2 and the oil-resistant layer coating solution-1 was changed to the oil-resistant layer coating solution-3 to obtain oil-resistant paper-4. .

<Example 5>
Except having changed oil-resistant layer coating liquid-1 into oil-resistant layer coating liquid-4, operation similar to Example 1 was performed and oil-resistant paper-5 was obtained.

<Example 6>
Except having changed oil-resistant layer coating liquid-1 into oil-resistant layer coating liquid-5, operation similar to Example 1 was performed and oil-resistant paper-6 was obtained.

<Example 7>
Except having changed oil-resistant layer coating liquid-1 into oil-resistant layer coating liquid-6, operation similar to Example 1 was performed and oil-resistant paper-7 was obtained.

<Comparative Example 1>
The base material 1 was not coated, and oil-resistant paper-8 was obtained.

<Comparative Example 2>
Except having changed the base material-1 into the base material-4, operation similar to Example 2 was performed and the oil-resistant paper-9 was obtained.

<Comparative Example 3>
Although the base material-3 was produced as above-mentioned, intensity | strength was low and normal paper was not able to be produced.

[Evaluation method]
(Oil resistance evaluation 1)
As oil resistance evaluation 1, 0.5 g of edible oil was dropped on the oil-resistant surface of the oil-resistant paper, left for 30 minutes, wiped off with a tissue, and the size of the oil spot was visually evaluated.
○: The size of the oil spot is less than half of the area in contact with the edible oil ×: The size of the oil spot is more than half of the area in contact with the edible oil

(Oil resistance evaluation 2)
For oil resistance evaluation 2, 0.5 g of edible oil was dropped on the oil-resistant surface of the oil-resistant paper, left for 30 minutes, wiped with a tissue, and the contrast between the oil spot and the part without oil spot was visually observed. Evaluated.
A: Low contrast of oil spots and less noticeable oil spots ○: Less contrast of oil spots and less noticeable oil spots ×: High contrast of oil spots and noticeable oil spots

※ 比較例３では、顔料が多すぎて紙にならなかった。製造不可。

* In Comparative Example 3, there was too much pigment and it did not become paper. Cannot be manufactured.

In Examples 1 to 7, since the size of the oil spot is small and the contrast of the oil spot is small, even if the oil passes through the oil resistant layer and penetrates into the base material in contact with the oil for a long time, It turns out that it is not conspicuous.
On the other hand, in Comparative Example 1, the oil spot is large, and in Comparative Example 2, the oil spot is greatly spread, and it can be seen that the contrast of the oil spot is conspicuous. In Comparative Example 3, normal paper with a large amount of filler could not be prepared.

  According to the present invention, it is possible to obtain an oil-resistant paper that suppresses the permeation of oil into the base material and that does not notice oil spots even if the oil passes through the oil-resistant layer and permeates the base material. For this reason, the oil-resistant paper of the present invention is preferably used as packaging paper for foods containing oil and fat components, oil-resistant paper for containers, and decorative board base paper that requires oil resistance and design, and has high industrial applicability. .

Claims (3)

An oil-resistant paper provided with at least one non-fluorinated oil-resistant layer on one side of a substrate,
The oil-resistant agent used in at least one of the oil-resistant layers is a starch-based or polyvinyl alcohol-based water-soluble resin,
The oil-resistant paper, wherein the amount of titanium oxide contained in the substrate is 20 to 40% by mass. The oil-resistant paper according to claim 1, wherein the water-soluble resin is ethylene-modified polyvinyl alcohol or carboxy group-modified polyvinyl alcohol. The oil-resistant paper according to claim 1 or 2, wherein a concealing layer containing titanium oxide is provided on a surface opposite to the surface provided with the oil-resistant layer of the substrate.