JP6003793B2 - Oil resistant paper and method for producing oil resistant paper - Google Patents

Description

  The present invention relates to oil-resistant paper and a method for producing oil-resistant paper. Specifically, the present invention relates to an oil-resistant paper having an oil-resistant layer capable of preventing permeation of oil and fat components such as animal and vegetable oils and fats, and a method for producing the 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, so that the oil and fat components of food do not penetrate into the packaging paper. 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-fluorine-based oil resistant agent is applied with a bar coater or a blade 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, uneven coating occurs, which may reduce the oil resistance of the oil resistant layer.
In order to cope with such a problem, a method of adding a silicone-based antifoaming agent or a hydrophobic silica-based antifoaming agent to a coating liquid containing a non-fluorinated oilproofing agent has been proposed (for example, Patent Document 4 and 5). This suppresses foaming of the coating liquid and enhances the coating suitability.

JP 2009-120996 A JP 2011-26745 A JP 2011-185812 A Japanese Patent Laid-Open No. 11-277877 JP 2009-84404 A

  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, since the polyvinyl alcohol-based resin forms a strong hydrophilic film, it is possible to prevent the penetration of oil, but there is a problem that water may be penetrated and sufficient water resistance cannot be exhibited. there were.

  Therefore, in order to solve the problems of the prior art, the present inventors have proceeded with a study for the purpose of providing an oil-resistant paper having a good coated surface state and excellent oil resistance and water resistance. . In addition, the present inventors have also studied for the purpose of increasing the production efficiency of oil-resistant paper by forming oil-resistant paper from a coating solution having excellent coating stability.

As a result of intensive studies to solve the above problems, the present inventors have improved coating stability by adding a carboxy group-modified polyvinyl alcohol and a pigment to a coating solution for forming an oil-resistant layer. I found out that I can. Furthermore, the present inventors have found that the oil-resistant paper having the oil-resistant layer thus obtained has a good coated surface state and excellent oil resistance and water resistance, and completes the present invention. It came to.
Specifically, the present invention has the following configuration.

[1] An oil-resistant paper having a non-fluorine-based oil-resistant layer on at least one surface of a base material, wherein the oil-resistant layer contains a carboxy group-modified polyvinyl alcohol and a pigment.
[2] The oil-resistant paper according to [1], wherein the pigment is kaolin.
[3] The oil-resistant paper according to [1] or [2], wherein the oil-resistant layer contains a water-insoluble resin, and the glass transition temperature of the water-insoluble resin is 50 ° C. or lower.
[4] The oil-resistant paper according to [3], wherein the water-insoluble resin is a styrene-butadiene copolymer resin or an acrylic resin.
[5] The content of the carboxy group-modified polyvinyl alcohol is 0.1 to 50% by mass with respect to the total solid mass of the oil-resistant layer, according to any one of [1] to [4] Oil-resistant paper as described.
[6] The oil resistance according to any one of [3] to [5], wherein the content of the water-insoluble resin is 5 to 60% by mass with respect to the total solid mass of the oil-resistant layer. paper.
[7] The mass ratio of the carboxy group-modified polyvinyl alcohol and the water-insoluble resin contained in the oil resistant layer is 1: 9 to 7: 3, according to any one of [3] to [6] Oil resistant paper.
[8] The oil resistant paper according to any one of [1] to [7], wherein the base material contains pulp as a main component.
[9] including a step of forming an oil-resistant layer by applying a coating solution containing a carboxy group-modified polyvinyl alcohol and a pigment on at least one surface of the substrate, and in the step of forming the oil-resistant layer, the coating solution Is a method for producing oil-resistant paper, which is coated using a bar coater or a blade coater.
[10] An oil-resistant paper produced by the production method according to [9].

  According to the present invention, it is possible to obtain an oil resistant paper having a good coated surface state and excellent oil resistance and water resistance. In the present invention, since the coating solution for the oil resistant layer containing the oil resistant agent is excellent in coating stability, the production efficiency of the oil resistant paper can be remarkably increased. Furthermore, since the oil-resistant paper of the present invention has both oil resistance and water resistance, it is preferably used as a packaging paper for foods and the like containing a large amount of oil and fat components and moisture.

FIG. 1 is a schematic cross-sectional view of the oil-resistant paper of the present invention.

  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 relates to an oil-resistant paper having a non-fluorine-based oil-resistant layer on at least one surface of a base material, wherein the oil-resistant layer contains a carboxy group-modified polyvinyl alcohol and a pigment. Oil-resistant paper can be used as packaging paper for foods containing oil and fat components, etc., and by packaging food with an oil-resistant layer on the side that comes into contact with food, the oil and fat components of food can be oozed out. Can be suppressed. The oil-resistant paper of the present invention can be used not only for packaging paper but also for sheets such as cooking paper, paper containers, and building material paper for kitchens that require oil resistance.
Moreover, since the oil-resistant paper of the present invention uses a non-fluorine-based oil-resistant agent as an oil-resistant agent, no fluorine compound is generated even when the oil-resistant paper is heated or incinerated. For this reason, the oil-resistant paper of the present invention has the advantages of high safety and low environmental load.

  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 carboxy group-modified polyvinyl alcohol as described later as the non-fluorinated oil resistant agent.

(Oil resistant layer)
In the present invention, the oil resistant layer contains carboxy group-modified polyvinyl alcohol. Carboxy group-modified polyvinyl alcohol is a non-fluorinated oil-resistant agent and can impart oil resistance to oil-resistant paper. In addition, by adding carboxy group-modified polyvinyl alcohol to the coating solution for forming the oil-resistant layer, foaming of the coating solution can be suppressed. It can be obtained without addition.
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 coating surface state of an oil-resistant layer can be improved.

Carboxy group-modified polyvinyl alcohol is a modified product obtained by binding carboxylic acid or carboxylic anhydride to polyvinyl alcohol. The content of carboxylic acid or carboxylic anhydride in the carboxy group-modified polyvinyl alcohol is 0.1 to 10% by mass, preferably 0.5 to 8% by mass, more preferably 1 to 5% by mass, and 2 to 4%. More preferred is mass%.
Examples of the carboxy group-modified polyvinyl alcohol include compounds described in JP-B-62-23117. Here, the carboxy group-modified polyvinyl alcohol can be obtained by homogenous solution copolymerization of vinyl acetate and ethylenically unsaturated dicarboxylic acid in the presence of alcohol, and saponifying the copolymer using an alkali. it can. The mass ratio of vinyl acetate and ethylenically unsaturated dicarboxylic acid at this time is in the range of 100: 0.01-5. In the case of saponification with an alkali, 0.001 to 1. mol of an alkali equivalent to 2 molar equivalents with respect to the ethylenically unsaturated dicarboxylic acid unit in the copolymer and the vinyl acetate unit in the copolymer. It is preferred to use a total amount of alkali with 0 molar equivalents of alkali.

  The content of the carboxy group-modified polyvinyl alcohol is preferably 0.1 to 50% by mass, and 1 to 40% by mass with respect to the total solid content of the oil-resistant layer (total solid content of the coating liquid). More preferably, it is more preferably 3 to 20% by mass. By setting the content of the carboxy group-modified polyvinyl alcohol within the above range, the oil resistance of the oil resistant layer can be sufficiently enhanced. 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.

  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.

  In the present invention, the average particle size of kaolin is preferably 1 to 100 μm, more preferably 3 to 50 μm, and further preferably 4 to 20 μm. By making the average particle diameter of kaolin within the above range, the coating stability can be enhanced, and an oil-resistant layer excellent in oil resistance and water resistance can be formed.

Moreover, it is preferable that kaolin is flat plate shape. The average aspect ratio of kaolin used in the present invention is preferably 50 or less, and more preferably 20 or less. Here, the aspect ratio of kaolin is represented by the ratio between the particle diameter and the particle thickness. In the present invention, coating stability can be improved by using kaolin having an average aspect ratio of 50 or less. This is considered to be because the interaction between kaolin and carboxy group-modified polyvinyl alcohol can be reduced by using kaolin having an average aspect ratio of 50 or less. Further, by using kaolin as described above, it is possible to achieve both smoothness and coverage of the oil-resistant layer.
As a method for measuring the particle size of the inorganic pigment having a flat plate shape, there are a method for obtaining an average particle size by a microtrack laser diffraction method, a micro-sheath mesh screen method, a method for obtaining by observation with an electron microscope, and the like. There are differences in the numerical value of the particle diameter depending on the measurement method, but the particle diameter determined by the micro-sheet mesh sieve method and observation by an electron microscope is close to the actual particle diameter. Larger value. However, the average particle size of the kaolin of the present invention was measured by a microtrack laser diffraction method because of its ease of measurement and high reproducibility.
In the present invention, the aspect ratio of kaolin having a flat plate shape is obtained by dividing the average particle diameter of kaolin by the thickness, and the thickness of kaolin was measured by observation with an electron microscope.

  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 pigment content in the above range, water resistance can be imparted in addition to oil resistance, and an oil resistant layer having excellent oil resistance and water resistance can be formed.

  In this invention, it is preferable that an oil-resistant layer contains water-insoluble resin, and it is preferable that the glass transition temperature of water-insoluble resin is 50 degrees C or less. 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 resins, carboxymethyl cellulose resins, polyethylene terephthalate resins, polyamide resins, starches, modified starches, amyloses, amylopectins, vinyl chloride resins, vinylidene chloride resins, silicone resins, acrylic resins and waxes And a mixture of styrene-acrylic resin and wax. 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.

  The styrene-butadiene copolymer resin contributes to the formation of a coating layer having a high degree of water resistance, and is obtained by copolymerizing styrene and butadiene as monomers. The styrene-butadiene copolymer resin that can be used in the present invention is different from the styrene-butadiene copolymer resin usually used for paper coating such as coated paper and special paper, but methyl methacrylate, acrylonitrile, etc. The other monomer is preferably not copolymerized with styrene or butadiene. Incidentally, a styrene-butadiene copolymer resin obtained by copolymerizing monomers such as methyl methacrylate and acrylonitrile is not preferred for use in the present invention because of its low water resistance. In addition, as a styrene-butadiene copolymer resin that can be used in the present invention, a widely used styrene-butadiene copolymer can be used, for example, “X300B” commercially available from JSR Corporation. be able to. The glass transition temperature of the styrene-butadiene copolymer 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 (Tg) to 50 ° C. or less, the oil resistant layer can exhibit high film forming ability and excellent oil resistance. In the present invention, Tg is obtained by differential scanning calorimetry (DSC) according to the method for measuring the transition temperature of JIS K 7121-1987 plastic.

  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. Acrylic copolymers, ethylene-acrylic acid copolymer sodium salts, ethylene-acrylic acid copolymer water-soluble salts such as ammonium salts of ethylene-acrylic acid copolymers, copolymer emulsions of acrylamide and acrylic acid (methacrylic acid) And a copolymer emulsion 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 styrene-butadiene copolymer resin and acrylic resin used in the present invention preferably have an average particle size of 0.01 to 1.0 μm. If the average particle diameter is within this range, water dispersibility will be good. If the average particle size is less than 0.01 μm, the mechanical stability during coating may be deteriorated, and if it exceeds 1.0 μm, the high shear viscosity is low, and a desired coating amount cannot be obtained. There is a risk that coating defects such as streaks may occur on the coated surface. Here, the average particle size of the resin emulsion is measured with a light scattering particle size distribution analyzer (trade name: LB-550, manufactured by HORIBA).

  In the present invention, it is necessary to control the viscosity of the oil-resistant layer coating solution in order to ensure coating suitability in a bar coater or blade coater. For this reason, it is preferable to make the molecular weight (weight average molecular weight) of water-insoluble resin into 50,000-2 million. The molecular weight of the water-insoluble resin can be appropriately adjusted by controlling the reaction temperature, reaction time, average particle size, and acid value 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.

  The content of the water-insoluble resin is preferably 5 to 60% by mass, and preferably 10 to 50% by mass with respect to the total solid content of the oil-resistant layer (total solid content of the coating liquid). More preferably, it is 15-45 mass%. By setting the content of the water-insoluble resin within the above range, water resistance can be imparted in addition to oil resistance, and an oil-resistant layer excellent in oil resistance and water resistance can be formed.

  In the present invention, the mass ratio of the carboxy group-modified polyvinyl alcohol and the water-insoluble resin contained in the oil resistant layer is preferably 1: 9 to 7: 3, and more preferably 2: 8 to 6: 4. . By setting the mass ratio of the carboxy group-modified polyvinyl alcohol and the water-insoluble resin within the above range, an oil-resistant paper excellent in both oil resistance and water resistance can be obtained.

  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.

(Base material)
The base material used for the oil-resistant paper of the present invention is not particularly limited as long as it can provide an oil-resistant layer on at least one surface. For example, a material mainly composed of plant-derived pulp is used. Is preferred. For example, high-quality paper, medium-quality paper, fine-coated paper, coated paper, glossy paper, bleached or unbleached kraft paper (acidic paper or neutral paper), or for corrugated board, for building materials, for white balls, Paperboard, white paperboard or the like used for chipboard can be used. Although the basis weight of the substrate is not particularly limited, as the wrap 20 to 150 g / m ^2, as the for molding vessel such as a box are preferred 150~500g / m ^2.

  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 70 g / m ² , and the Oken air permeability is preferably 70 seconds or more. By setting the basis weight of the base material within the above range, it is possible to maintain a required strength that can maintain a required strength when the oil-resistant layer is formed. If the basis weight of the base material exceeds 70 g / m ² , the base material is likely to buckle at the crease portion, so that the base material is cracked and the oil resistance of the fold tends to decrease. In addition, the JAPAN TAPPI paper pulp test method No. When the Oken air permeability measured according to 5-2: 2000 is less than 70 seconds, the elongation of the folded portion of the base paper becomes small, and the oil resistance tends to decrease. The upper limit of the Oken air permeability is not particularly limited, but is preferably 400 seconds or less.

  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 using a breaker stack in wet paper when making the substrate, using a machine calendar, soft nip calender, gloss calendar after drying, or after making the substrate One example is the use of a super calendar. Among them, a breaker stack used for wet paper is preferable because it can apply pressure in a state where the paper moisture is high and can efficiently increase the density even when compared with calendering after drying.

  Further, the thickness of the substrate is preferably 50 μm or more, and more preferably 70 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 typified by urea-formalin resin particles, polyacrylamide polymers, paper strength enhancers typified by starch, melamine resins, urea resins, polyamide-polyamines Examples include wet paper strength enhancers typified by epichlorohydrin resins and the like, and other auxiliaries such as dyes, pigments, and fluorescent dyes for color tone adjustment such as filtering agents and bluing.

(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 calendar. .
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 liquid containing carboxy group-modified polyvinyl alcohol and a pigment 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 metering blade type size press coater, a bill blade coater, a short dwell coater, a gate roll coater, a nip coater using a calendar, and the like are appropriately used. Among these, in order to increase production efficiency, it is preferable to use a bar coater or a blade coater, and more preferably a blade coater.

  In addition, by using a bar coater or a blade coater, high-speed coating becomes possible and production efficiency can be increased. However, coating by a bar coater or blade coater is the most among the various coating methods as described above. Performed under harsh conditions. This means that heat or pressure is likely to be applied to the coating liquid during coating with a bar coater or a blade coater. In addition, when the concentration of paint such as carboxy group-modified polyvinyl alcohol or pigment is increased, the paint is likely to be immobilized after coating (it is easy to dry and solidify), so that foreign matter is generated inside the paint before coating. When an excessive coating liquid is removed using a bar coater or a blade coater, foreign matter may be caught on the blade tip, and defects such as streak and bleeding may easily occur. On the other hand, if the coating amount is reduced and the paint to be dried is reduced, it is necessary to increase the pressing pressure of the blade when scraping a lot of coating liquid using a blade coater. There is a tendency that streaks are likely to occur.

However, in the present invention, by containing carboxy group-modified polyvinyl alcohol in the oil-resistant layer, even when coating is performed using a bar coater or a blade coater, no coating defects are caused. The working condition can be improved. That is, the coating liquid used in the present invention does not increase the viscosity of the coating liquid even when it is applied using a bar coater or a blade coater, and is immobilized after coating. Can be prevented. In addition, the occurrence of streaks due to the pressing pressure of the blade can be suppressed.
As described above, in the present invention, the oil-resistant layer can be applied by a bar coater or a blade coater, and it can be applied even under such severe conditions, so that the coating suitability of the coating liquid is sufficiently high. Means that.

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, an oil-resistant layer tends to be obtained more easily in a multi-layer configuration than in a single-layer configuration. 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.

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. In the following, Examples 2 to 6 and 10 shall be read as Reference Examples 2 to 6 and 10, respectively.

<Example 1>
(1) Preparation of oil-resistant layer coating solution A-1 As a water-soluble resin, 42.0 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.), a water-insoluble resin 20.4 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”) , Manufactured by BASF) 30.0 parts by mass of a 70% aqueous dispersion and water (7.58 parts by mass) were mixed and stirred to obtain an oil-resistant layer coating solution A-1 having a coating solution solid content concentration of 35% by mass. It was.

(2) Production of Oil Resistant Paper-1 Substrate with a basis weight of 50 g / m ² [Semi-Glasin Paper (Freeness 195 ml · CSF, LBKP 100%, JAPAN TAPPI, Paper Pulp Test Method No. 5: 2000, Oken Air Permeability of Substrate : 100,000 seconds or more)] is coated on the one surface of the oil-resistant layer coating solution A-1 so that the solid content is 3.0 g / m ² using a vent blade, and then a hot air dryer is used. It was used and dried at 110 ° C. for 1 minute to provide a printing surface side oil resistant layer to obtain oil resistant paper-1 of the present invention.

<Example 2>
(1) Preparation of oil-resistant layer coating solution B-1 37.9 parts by weight of a 10% aqueous solution of carboxy group-modified polyvinyl alcohol (trade name: “Exeval KL-118” manufactured by Kuraray Co., Ltd.), an acrylic resin as a water-insoluble resin (Trade name: “PDX7326N”, manufactured by BASF Japan, glass transition temperature: 9 ° C.) 22.6 parts by weight of 39% aqueous dispersion, kaolin (trade name: “Ultra White 90”, manufactured by BASF) 70% 27.1 parts by mass of the aqueous dispersion and water (2.66 parts by mass) were mixed and stirred to obtain an oil-resistant layer coating liquid B-1 having a coating liquid solid content concentration of 35% by mass.

(2) Production of Oil Resistant Paper-2 The same operation as in Example 1 was performed except that (2) oil resistant paper coating liquid A-1 of oil resistant paper in Example 1 was changed to oil resistant paper coating liquid B-1. The oil-resistant paper-2 of the present invention was obtained.

<Example 3>
In the preparation of (1) oil-resistant layer coating liquid A-1 in Example 1, a styrene-butadiene copolymer latex (trade name: “SR-115”, manufactured by Japan A & L, glass transition temperature: 37 ° C., concentration: 48%) to obtain an oil-resistant layer coating solution A-2. The same operation as in Example 1 was carried out except that (2) oil-resistant paper coating liquid A-1 of Example 1 was changed to oil-resistant layer coating liquid A-2. Obtained.

<Example 4>
In the preparation of the oil-resistant layer coating liquid B-1 in Example 2, the concentration of an acrylic resin (trade name: “JONCRYL 537J”, manufactured by BASF Japan, glass transition temperature: 49 ° C.) as a water-insoluble resin. It changed to 19.2 parts of 46% aqueous dispersion, and 0 mass part of water, and obtained oil-resistant layer coating liquid B-2. The same operation as in Example 1 was carried out except that (2) oil-resistant paper coating liquid A-1 of Example 1 was changed to oil-resistant layer coating liquid B-2. Obtained.

<Example 5>
In the preparation of (1) oil-resistant layer coating solution A-1 in Example 1, 0.6 parts by mass of carboxy group-modified polyvinyl alcohol, 71.0 parts by mass of kaolin, and water-insoluble resin The blending amount was changed to 28.4 parts by mass and water 81.0 parts by mass to obtain an oil-resistant layer coating solution A-3 having a coating solution solid content concentration of 35% by mass. The same operation as in Example 1 was carried out except that the oil-resistant paper coating liquid A-1 of Example 1 (2) oil-resistant paper was changed to the oil-resistant paper coating liquid A-3. Obtained.

<Example 6>
In the preparation of Example 1 (1) oil-resistant layer coating solution A-1, the blending amount of carboxy group-modified polyvinyl alcohol is 7.3 parts, the blending amount of kaolin is 77.2 parts, and the blending amount of the water-insoluble resin. Were changed to 15.5 parts and 77.7 parts by mass of water to obtain an oil-resistant layer coating solution A-4 having a coating solution solid content concentration of 35% by mass. The same operation as in Example 1 was carried out except that (2) oil-resistant paper coating liquid A-1 of Example 1 was changed to oil-resistant layer coating liquid A-4. Obtained.

<Example 7>
The same operation as in Example 1 was carried out except that (2) oil-resistant paper coating solution A-1 of Example 1 was diluted to a solid content concentration of 30% by mass and coated with a bar coater. Oil-resistant paper-7 was obtained.

<Example 8>
The same operation as in Example 1 was carried out except that the oil resistant layer coating solution A-1 for oil resistant paper of Example 1 was coated with a gate roll coater to obtain an oil resistant paper-8 of the present invention.

<Example 9>
In the preparation of (1) oil-resistant layer coating solution A-1 in Example 1, kaolin is a light calcium carbonate (trade name “TPS-121” manufactured by Okutama Kogyo Co., Ltd.) at a concentration of 35.0 parts by weight in an aqueous dispersion of 35.0 parts by mass, It changed to water (2.58 parts), and obtained the oil-resistant layer coating liquid C-2. In the production of (3) oil-resistant paper-1 in Example 1, the same operation as in Example 1 was carried out except that the oil-resistant layer coating solution A-1 was changed to the oil-resistant layer coating solution C-2. 9 was obtained.

<Example 10>
In preparation of (1) oil-resistant layer coating solution A-1 in Example 1, SBR (trade name: “SR-140” manufactured by Japan A & L, glass transition temperature: 60 ° C., concentration: 48%) And oil-resistant layer coating solution C-3 was obtained. In the production of (3) oil-resistant paper-1 in Example 1, the same operation as in Example 1 was carried out except that the oil-resistant layer coating solution A-1 was changed to the oil-resistant layer coating solution C-2. 10 was obtained.

<Comparative Example 1>
(1) Preparation of Oil Resistant Layer Coating Liquid C-1 37.9 parts by weight of 10% aqueous solution of ethylene-modified polyvinyl alcohol (trade name: “Exeval HR3010” manufactured by Kuraray Co., Ltd.), acrylic resin (trade name) : 18.4 parts by weight of 39% aqueous dispersion of “PDX7326N”, manufactured by BASF Japan, glass transition temperature 9 ° C., 70% aqueous dispersion 27 of kaolin (trade name: “Ultra White 90”, manufactured by BASF) An oil-resistant layer coating solution C-1 having 0.1 part by mass, 2.66 parts by mass of water, and a coating solution solid content concentration of 35% by mass was obtained.

(2) Production of oil-resistant paper-9 The same operation as in Example 1 was carried out except that (2) oil-resistant paper coating liquid A-1 of oil-resistant paper in Example 1 was changed to oil-resistant layer coating liquid C-1. The oil-resistant paper-11 of the present invention was obtained.

<Comparative example 2>
The oil-resistant layer paint was composed of a 10% solution of only carboxy-modified polyvinyl alcohol (trade name: “GOHSENAL T330” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) to obtain an oil-resistant layer paint C-2.
The same operation as in Example 1 was performed except that the oil-resistant paper coating liquid A-1 of Example 1 (2) oil-resistant paper was changed to the oil-resistant paper coating liquid C-2. Obtained.

  Each oil resistant paper obtained in Examples and Comparative Examples was evaluated by the following method. The evaluation results are shown in Table 1.

[Evaluation method]
(Paint stability evaluation method 1)
As an evaluation of paint stability, with a Marlon machine stability tester (manufactured by Yasuda Seiki Seisakusho), rotation speed: 1000 rpm, temperature: 40 degrees, load: 10 kgf, and the rate of paint residue after 200 mesh passes before and after It was measured.
○: Occurrence rate 0.5% or less △: Occurrence rate 0.5% to 1% or less ×: Occurrence rate 1.0%

(Paint stability evaluation method 2)
As an evaluation of paint stability, after preparing the paint, the B-type viscosity was measured at a paint temperature of 25 ° C. to confirm the tendency of the paint to thicken.
○: No tendency to thicken paint even after 1 week.
(Triangle | delta): The tendency for the viscosity of the paint to increase is observed within 3 days to 1 week.
X: The tendency of thickening of the paint is observed within 2 days.

(Paint stability evaluation method 3)
As an evaluation of the paint stability, with a gum-up tester (manufactured by Kumagai Riki Kogyo Co., Ltd.), speed: 150 m / min, temperature: 40 degrees, nip linear pressure: 18 kgf, and water retention before and after treatment is AA- Measurement was performed with a GWR water retention meter (manufactured by Kaltec Scientific, Inc.) under the conditions of pressure: 100 MPa, pressurization time: 30 seconds, membrane filter material: PTFE, and pore diameter: 0.5 μm.
○: No change in water retention of the paint before and after treatment Δ: Decrease in paint water retention after treatment is within 5.0 g / m ² ×: Paint water retention is less than 5.0 g / m ² after treatment

(Coated surface condition)
The state of the coated surface was inspected visually.
○: Defects are not visually observed.
Δ: There are some circular or elliptical defects due to bubbles.
X: There is a circular or elliptical defect due to bubbles. Or a streak defect (streaks) is seen.

(Oil resistance evaluation method)
As an evaluation of oil resistance, the oil resistance of the coated surface of the oil resistant layer was measured by the TAPPI UM-557 method (kit method). In addition, the oil resistance required in this invention is 3rd grade or more.

(Water resistance evaluation method)
As evaluation of water resistance, the water resistance of the coated surface of the oil-resistant layer at 60 seconds was measured according to JIS P 8140 (Cobb water absorption). The water resistance required in the present invention is 15 g / m ² or less.

In Examples 1-10, it turns out that the stability of a coating material is excellent and generation | occurrence | production of the coating residue at the time of application | coating of an oil-resistant layer is suppressed. It can also be seen that there is little increase in the viscosity of the coating liquid, and the water retention (stability) of the coating liquid is high. Moreover, in Examples 1-10, the coating surface state of the obtained oil-resistant layer is favorable. Furthermore, in Examples 1-10, it turns out that water resistance is excellent in addition to oil resistance. In particular, in Examples 1 to 7, it can be seen that the coating stability is high, which is a preferable embodiment.
On the other hand, in Comparative Example 1, since the carboxy group-modified polyvinyl alcohol is not used as the water-soluble resin, the stability of the paint is remarkably deteriorated, and the coated surface state of the oil resistant layer is also deteriorated. Moreover, in the comparative example 2, since the coating liquid is comprised only from carboxy-group-modified polyvinyl alcohol, it turns out that paint stability and a coating surface state are inferior, and water resistance is getting worse.

  According to the present invention, it is possible to obtain an oil resistant paper having a good coated surface state and excellent oil resistance and water resistance. For this reason, the oil-resistant paper of the present invention is preferably used as an oil-resistant paper for food packaging papers and containers containing oil and fat components and moisture, and has high industrial applicability.

2 Base material 4 Oil resistant layer 10 Oil resistant paper

Claims (6)

Having a non-fluorinated oil-resistant layer on at least one side of the substrate;
The oil-resistant layer includes a carboxy-modified polyvinyl alcohol , a pigment , and a styrene-butadiene copolymer resin having a glass transition temperature of 0 ° C. or lower.
The oil-resistant paper , wherein a mass ratio of the carboxy group-modified polyvinyl alcohol and the styrene-butadiene copolymer resin is 1: 9 to 7: 3 .   The oil-resistant paper according to claim 1, wherein the pigment is kaolin. The oil-resistant paper according to claim 1 or 2 , wherein the content of the carboxy group-modified polyvinyl alcohol is 1 to 40 % by mass with respect to the total solid mass of the oil-resistant layer. The content rate of the said styrene butadiene copolymer resin is 5-60 mass% with respect to the total solid content mass of the said oil-resistant layer, The oil resistance of any one of Claims 1-3 characterized by the above-mentioned. paper. The oil-resistant paper according to any one of claims 1 to 4 , wherein the base material contains pulp as a main component. Including a step of forming an oil-resistant layer on at least one surface of the base material by applying a coating liquid containing carboxy group-modified polyvinyl alcohol , a pigment , and a styrene-butadiene copolymer resin having a glass transition temperature of 0 ° C. or lower. ,
The mass ratio of the carboxy group-modified polyvinyl alcohol and the styrene-butadiene copolymer resin in the coating solution is 1: 9 to 7: 3,
In the step of forming the oil resistant layer, the coating liquid is applied using a bar coater or a blade coater.

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