JP2022085465A - Oil resistant paper - Google Patents

Abstract

To provide oil resistant paper having both high oil resistance and high gas permeability.SOLUTION: There is provided oil resistant paper 1 comprising a paper base material 10, an intermediate layer 20 and a surface layer 30, with the intermediate layer 20 being disposed at least on one surface of the paper base material 10, the surface layer 30 being disposed on the surface of the intermediate layer 20 opposite to the surface thereof whereon the paper base material 10 is disposed, the intermediate layer 20 containing polyvinyl alcohol, and the surface layer 30 containing a styrene-(meth)acrylate copolymer resin and a sizing agent.SELECTED DRAWING: Figure 1

Description

The present invention relates to oil resistant paper.

Oil-resistant paper is widely used as wrapping paper and wrapping containers for fast foods and fried foods containing a large amount of oil and water, cooked foods such as roasted foods, foods containing a large amount of oil and fat such as chocolate, and paper rugs such as food trays. There is.

Generally, a fluororesin-based oil-resistant agent is widely used as an oil-resistant agent that imparts oil resistance to paper. For example, an oil-resistant agent is provided by applying a fluororesin-based oil-resistant agent to the surface of a paper substrate. Paper and oil-resistant paper in which a fluororesin-based oil-resistant agent is embedded in a paper base material are known. However, it is difficult to handle the inert gas derived from the oil-resistant agent generated during combustion in the oil-resistant paper using the fluororesin-based oil-resistant agent, and an oil-resistant paper containing no fluororesin-based oil-resistant agent has been required.

As an oil-resistant paper that does not contain a fluororesin-based oil-resistant agent, for example, Patent Document 1 describes an oil-resistant paper having an undercoating layer and a topcoating layer on at least one side of a paper base material, and the above-mentioned undercoating. An oil resistant paper is disclosed in which the layer contains an oxidized starch and at least one of a fatty acid sizing agent and an alkyl ketene dimer, and the topcoat layer contains at least one of an oxidized starch and a styrene-butadiene copolymer. There is.

Further, Patent Document 2 describes an oil-resistant paper in which at least one layer of an oil-resistant layer containing an acrylic resin as a main component is provided on at least one side of the paper support, and the weight average molecular weight of the acrylic resin is 50,000 or more. An oil-resistant paper having 2 million and an acid value of 50 to 200 mgKOH is disclosed.

JP-A-2017-119921 Japanese Unexamined Patent Publication No. 2012-067402

However, when an oil resistant agent such as starch or acrylic resin is used, the coating is applied so that pinholes do not occur on the paper base material due to the development of the oil resistance, so that the air permeability becomes insufficient and the packaged food or the like is used. It becomes difficult for the water vapor generated from the oil-resistant paper to escape from the oil-resistant paper to the outside, and the bonds of the pulp fibers constituting the oil-resistant paper are loosened. This causes problems such as deterioration of oil resistance and deterioration of food flavor and storage stability.

Further, the oil resistance level (oil resistance) of the oil resistant paper is evaluated by an index called a kit value. The kit value is the JAPAN TAPPI pulp and paper test method No. Measured by 41: 2000. However, even if the oil-resistant paper has a good measured value of the kit value, the oil resistance may not be sufficient when it is actually used. When the inventors studied such an event, one of the causes was that when foods and the like packaged in oil-resistant paper were reheated in a microwave oven, the steam generated in the microwave oven caused the pulp fibers of the oil-resistant paper. I thought that this might be because the bonds were loosened and the oil components contained in the food could easily penetrate the front and back surfaces of the oil-resistant paper.

As described above, an oil-resistant paper capable of having both high oil resistance and high air permeability at a practical level has not yet been developed, and there is room for improvement in this respect.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an oil-resistant paper having both high oil resistance and high air permeability.

As a result of diligent studies to achieve the above-mentioned object, the present inventors have obtained an oil-resistant paper containing a paper base material, an intermediate layer, and a surface layer, and the intermediate layer is the surface of at least one of the paper base materials. The surface layer is provided on the surface opposite to the side on which the paper substrate of the intermediate layer is provided, the intermediate layer contains polyvinyl alcohol, and the surface layer is a styrene- (meth) acrylic copolymer resin. The present invention has been completed based on the knowledge that the composition contains a sizing agent and a sizing agent.

That is, the present invention is as follows.

(1)
An oil-resistant paper containing a paper base material, an intermediate layer, and a surface layer. The intermediate layer is provided on at least one surface of the paper base material, and the surface layer is a surface of the intermediate layer. An oil-resistant layer provided on the surface opposite to the side on which the paper substrate is provided, the intermediate layer containing polyvinyl alcohol, and the surface layer containing a styrene- (meth) acrylic copolymer resin and a sizing agent. It is paper.
(2)
The oil-resistant paper according to (1), wherein the sizing agent contains at least one selected from the group consisting of an olefin-based sizing agent, a rosin-based sizing agent, and an alkylketene dimer-based sizing agent.
(3)
The oil-resistant paper according to (1) or (2), wherein the dry adhesion amount of the polyvinyl alcohol in the intermediate layer is 0.2 to 0.6 g / m ² .
(4)
The oil-resistant paper according to (1) or (2), wherein the intermediate layer is provided on both sides of the paper base material.
(5)
The intermediate layer is provided on both sides of the paper substrate, and the total amount of the polyvinyl alcohol adhered to the intermediate layer on both sides is 0.4 to 1.2 g / m ² (4). It is the oil-resistant paper described in.
(6)
The oil-resistant paper according to (4) or (5), wherein the surface layer is provided on both sides of the paper substrate via the intermediate layer.
(7)
The dry adhesion amount of the styrene- (meth) acrylic copolymer resin on the surface layer is 1.2 to 3.6 g / m ² per one side of the paper substrate, whichever is (1) to (6). It is the oil-resistant paper described in.
(8)
The oil-resistant paper according to any one of (1) to (7), wherein the content of the sizing agent in the surface layer is 25 to 75% by mass in terms of solid content.
(9)
The oil-resistant paper according to any one of (1) to (8), wherein the oil-resistant paper has a Prussia-type air permeability of 2000 to 80,000 seconds in the JAPAN TAPPI pulp and paper test method.

According to the present invention, it is possible to provide an oil resistant paper having both high oil resistance and high air permeability.

FIG. 1 is a schematic cross-sectional view of the oil-resistant paper according to the first embodiment. FIG. 2 is a schematic cross-sectional view of the oil-resistant paper according to the second embodiment. FIG. 3 is a schematic cross-sectional view of the oil-resistant paper according to the third embodiment.

Hereinafter, embodiments for carrying out the present invention (hereinafter, simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and carried out within the scope of the gist thereof.

Then, in the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. In addition, the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown.

Further, in the present specification, unless otherwise specified, "(meth) acrylic" shall include methacrylic and acrylic. For example, (meth) acrylic means methacrylic, acrylic, or both.

FIG. 1 is a schematic cross-sectional view of the oil-resistant paper according to the first embodiment.

The oil-resistant paper 1 according to the present embodiment is an oil-resistant paper 1 including a paper base material 10, an intermediate layer 20, and a surface layer 30, and the intermediate layer 20 is provided on at least one surface of the paper base material 10. The surface layer 30 is provided on the surface of the intermediate layer 20 opposite to the side on which the intermediate layer 20 of the paper substrate 10 is provided, and the intermediate layer 20 contains polyvinyl alcohol and the surface layer 30 is provided. Contains a styrene- (meth) acrylic copolymer resin and a sizing agent. That is, the oil-resistant paper 1 has a structure in which the paper base material 10, the intermediate layer 20, and the surface layer 30 are laminated in this order. For example, when the oil-resistant paper 1 is used for a food packaging bag or the like, the surface layer 30 is a layer in contact with the food to be stored, and when the oil-resistant paper 1 is processed into a packaging bag, it is the inner surface thereof.

According to the present embodiment, it is possible to obtain an oil-resistant paper having both high oil resistance and high air permeability. In particular, as a preferred embodiment thereof, even if the oil-resistant paper 1 is an oil-resistant paper that does not substantially contain a fluororesin, it can exhibit such high oil resistance and high air permeability. Therefore, the oil-resistant paper 1 can be used as a wrapping paper or wrapping container for fast foods and fried foods containing a large amount of oil and water, cooked foods such as roasted foods, foods containing a large amount of oil and fat such as chocolate, and paper rugs such as food trays. Can be suitably used. Further, it can be suitably used as a non-fluororesin-based oil-resistant paper 1.

Hereinafter, each component will be described.

(Middle layer)

By providing the intermediate layer 20, the coating liquid that becomes the surface layer 30 during manufacturing is controlled so as to stay uniformly on the surface of the paper base material 10, and even if the surface layer 30 has a low adhesion amount, sufficient oil resistance is sufficient. Can be demonstrated. Further, by reducing the total amount of adhesion of the surface layer 30 and the intermediate layer 20, the texture of the oil-resistant paper 1 can be made closer to that of ordinary paper. Further, the intermediate layer 20 of the oil resistant paper 1 contains polyvinyl alcohol. By containing polyvinyl alcohol in the intermediate layer 20, it is possible to impart excellent oil resistance and moisture permeability to the oil resistant paper.

Examples of the polyvinyl alcohol used for the intermediate layer 20 include unmodified polyvinyl alcohol and modified polyvinyl alcohol, and examples thereof include fully saponified polyvinyl alcohol and partially saponified polyvinyl alcohol, respectively. As the modified polyvinyl alcohol, α-olefin-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, acetacetyl-modified polyvinyl alcohol, mercapto-modified polyvinyl alcohol and the like can be used.

The degree of saponification of polyvinyl alcohol is from the viewpoint of exhibiting a barrier property to the extent that the coating liquid for the surface layer (coating liquid constituting the surface layer 30) applied to the surface of the intermediate layer 20 does not permeate to the paper base material 10. Therefore, the degree of saponification expressed by the molar ratio of the saponified ester group to the ester group that existed before the saponification is preferably 80 to 100%. Further, from the viewpoint of imparting appropriate air permeability so as not to trap food-derived water vapor inside the oil-resistant paper bag, the saponification degree is more preferably 90% or more, and further preferably 95% or more. It is preferably 98% or more, and even more preferably 98% or more.

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

From the viewpoint of further improving the barrier property of the intermediate layer 20 and the air permeability of the oil resistant paper, it is preferable that the intermediate layer 20 is made of only polyvinyl alcohol. The term "only" as used herein means that a substance other than the component concerned is not positively added or mixed, and does not exclude unavoidable inclusion or mixing. In this case, it is suitable for coating means. Polyvinyl alcohol can be diluted with water and used in order to adjust the concentration and viscosity. In the intermediate layer 20, other additives such as a dispersant, an antifoaming agent, and a colorant are appropriately selected and used as long as the effects of the present embodiment are not impaired. You can also do it.

The dry adhesion amount of polyvinyl alcohol in the intermediate layer 20 is preferably 0.2 to 0.6 g / m ² . The dry adhesion amount referred to here is, for example, the dry adhesion amount per one side of the paper base material 10 when the intermediate layer 20 is provided only on one side of the paper base material 10. Further, for example, when the intermediate layer 20 and the intermediate layer 40 are provided on both surfaces of the paper substrate 10 in the same area (for example, see FIG. 2), 1 / of the total dry adhesion amount of the intermediate layer 20 and the intermediate layer 40. It is twice the amount of dry adhesion. The lower limit of the dry adhesion amount is more preferably 0.25 g / m ² or more, and further preferably 0.3 g / m ² or more. Further, the upper limit of the dry adhesion amount is more preferably 0.55 g / m ² or less, and further preferably 0.5 g / m ² or less.

(Surface layer)

The surface layer 30 contains a styrene- (meth) acrylic copolymer resin and a sizing agent. The combined use of a styrene- (meth) acrylic resin with high barrier properties and a sizing agent contributes to maintaining both oil resistance and moisture permeability at a high level. Styrene- (meth) acrylic resin means styrene-acrylic resin, styrene-methacrylic resin, or both.

When used as wrapping paper or wrapping container for fast foods containing a lot of oil and water, cooked foods such as fried foods and roasted foods, foods containing a lot of oils and fats such as chocolate, or paper rugs such as food trays, warm them with a microwave oven. do. Under such a practical environment, there is a problem that the oil resistance and air permeability of the oil resistant paper cannot be maintained at a practical level.

When the present inventors studied this problem, when pulp fibers were bonded to each other by coating a styrene- (meth) acrylic copolymer resin having high film-forming property on the surface of the paper base material 10, the oil resistance of the paper was improved. Although it improves, it traps even the water vapor generated in the microwave, which reduces the flavor and texture of the food. When the coating amount of the styrene- (meth) acrylic copolymer resin was reduced, the fibers of the paper base material 10 were loosened by the steam generated in the microwave oven, and the oil resistance of the oil-resistant paper was insufficient. Therefore, it was considered that such a problem could not be solved by controlling the film-forming property of the styrene- (meth) acrylic copolymer resin. Based on this idea, as a result of further diligent research, surprisingly, polyvinyl alcohol was blended in the intermediate layer 20, and not only the styrene- (meth) acrylic copolymer resin but also the sizing agent was used in combination with the surface layer 30. As a result, the moisture permeability could be improved without lowering the barrier property of the surface layer. Thereby, it is considered that oil resistance, air permeability, and moisture permeability in a practical environment can be maintained at a high level (however, the action of this embodiment is not limited to these).

The styrene- (meth) acrylic copolymer resin has high barrier properties and excellent water resistance. Further, it has an effect of improving the oil resistance of the intermediate layer 20. The styrene- (meth) acrylic copolymer resin is not particularly limited, and known substances can be used.

Examples of the constituent monomer of the styrene- (meth) acrylic copolymer resin include a copolymer containing at least a styrene-based monomer and a (meth) acrylic-based monomer. Further, as long as the monomer composition of the copolymer resin is satisfied, other monomers copolymerizable with the constituent monomer components of the styrene- (meth) acrylic copolymer resin can be used in combination, if necessary. The ratio of the styrene-based monomer and the (meth) acrylic-based monomer in the constituent monomers of the styrene- (meth) acrylic copolymer resin is preferably 50 mol% or more, more preferably 70 mol% or more. It is even more preferably 80 mol% or more, further preferably 90 mol% or more, and even more preferably a copolymer of substantially only these two monomers. The term "substantially" as used herein does not exclude so-called inevitably contained or mixed components.

The styrene-based monomer is not particularly limited, and for example, styrene, α-methylstyrene, β-methylstyrene, 2,4-dimethylstyrene, α-ethylstyrene, α-butylstyrene, 4-methoxystyrene, vinyltoluene and the like. Can be mentioned.

The (meth) acrylic monomer is not particularly limited, and for example, (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. , 3-ethoxypropyl acrylate, 3-ethoxybutyl acrylate, hydroxyethyl methacrylate and other (meth) acrylic acid ester derivatives, phenyl acrylate, benzyl acrylate and other acrylic acid aryl esters and acrylic acid aralkyl esters, diethylene glycol, triethylene Examples thereof include monoacrylic acid esters of polyhydric alcohols such as glycol and glycerin.

The weight average molecular weight of the styrene- (meth) acrylic copolymer resin is preferably 10,000 to 5,000,000. The lower limit of the weight average molecular weight is more preferably 50,000 or more, and further preferably 200,000 or more. Further, the upper limit of the weight average molecular weight is more preferably 2000000 or less, and further preferably 800,000 or less. Within such a range, the balance between oil resistance and air permeability can be achieved at a higher level.

The glass transition point of the styrene- (meth) acrylic copolymer resin is preferably −50 to 100 ° C. The lower limit of the glass transition point is more preferably −30 ° C. or higher, further preferably −20 ° C. or higher. Further, the upper limit of the glass transition point is more preferably 30 ° C. or lower, further preferably 10 ° C. or lower. If it is within the above range, the oil resistance is excellent.

The dry adhesion amount of the styrene- (meth) acrylic copolymer resin in the surface layer 30 is preferably 1.2 to 3.6 g / m ² per one side of the paper substrate 10. The lower limit of the dry adhesion amount is more preferably 1.5 g / m ² or more, and further preferably 2.0 g / m ² or more. Further, the upper limit of the dry adhesion amount is more preferably 3.0 g / m ² or less, and further preferably 2.5 g / m ² or less. If the amount of dry adhesion of the styrene- (meth) acrylic copolymer resin is within this range, dew condensation will occur even if the food is heated in a microwave oven or the like while maintaining the oil resistance and the practical oil resistance at a higher level. It becomes difficult.

The sizing agent can impart a sufficient level of oil resistance to the surface layer 30. Examples of the sizing agent include olefin-based sizing agents, rosin-based sizing agents, acrylic-based sizing agents, polyacrylamide-based sizing agents, styrene-maleic acid-based sizing agents, acrylic copolymer-based sizing agents, and acrylic emulsion-based sizing agents. Examples thereof include olefin-maleic acid resin-based sizing agents, urethane-based sizing agents, AKD (alkylketene dimer) / ASA (alkenyl anhydride succinic acid) -based sizing agents, and petroleum resin-based sizing agents. Among these, it is preferable to include at least one selected from the group consisting of an olefin-based sizing agent, a rosin-based sizing agent, and an alkylketene dimer-based sizing agent. The ionicity of the sizing agent may be cationic, anionic, or nonionic, but anionic is preferable.

The content of the sizing agent in the surface layer 30 is preferably 25 to 75% by mass in terms of solid content. The lower limit of this content is more preferably 35% by mass or more, further preferably 40% by mass or more. Further, the upper limit of this content is more preferably 65% by mass or less, and further preferably 60% by mass or less.

The content ratio of the sizing agent to the styrene- (meth) acrylic copolymer resin in the surface layer 30 (sizing agent / styrene- (meth) acrylic copolymer) is not particularly limited, but may be, for example, 25 to 75% by mass. preferable. The lower limit of this ratio is more preferably 35% by mass or more, and further preferably 40% by mass or more. Further, the upper limit of this ratio is more preferably 65% by mass or less, and further preferably 60% by mass or less.

For the surface layer 30, other additives such as a dispersant, an antifoaming agent, and a colorant may be appropriately selected and used as needed, as long as the effects of the present embodiment are not impaired. can. Moreover, it is preferable that it does not contain a fluororesin.

According to the present embodiment, the surface layer 30 may be a single layer or a plurality of two or more layers.

Further, according to the present embodiment, other functional layers (for example, a printing layer, a printing receiving layer, an adhesive layer for bag making processing) and the like may be provided in addition to the intermediate layer 20 and the surface layer 30. For example, a functional layer such as a print layer or a cover layer may be provided on the surface of the surface layer 30. For example, when used as a packaging bag for food, a printing layer may be provided on the outer surface without providing a printing layer on the inner side surface in contact with the food.

(Paper base material)

The paper base material 10 is not particularly limited and can be appropriately selected and used depending on the intended use. For example, bleached or unbleached kraft paper (acidic paper or neutral paper), high-quality paper, medium-quality paper, and fine paper can be used. Examples thereof include coated paper, coated paper, liner, semi-glass paper, glass paper, single-gloss paper, parchment paper paperboard, and white paperboard. Among these, glassine paper is preferable from the viewpoint of oil resistance.

Examples of the pulp constituting the paper base material 10 include wood pulp, non-wood pulp, used paper pulp, synthetic fiber pulp and the like. Examples of wood pulp include chemical pulp and mechanical pulp of softwood and hardwood. Examples of non-wood pulp include kenaf pulp, bagas pulp, rug pulp, linen pulp, hemp pulp, mulberry pulp, sansho pulp, ganpaku pulp, straw pulp, bamboo pulp and the like. Examples of the used paper pulp include used magazine paper, used leaflet paper, used colored paper, used newspaper, Kent used paper, used white paper, coated used paper, used copy paper, and used waste paper. Examples of the synthetic fiber pulp include rayon resin, vinylon resin, polyolefin resin, polyester resin, acrylic resin, polyamide resin, polybaraphenylene resin, polyurethane resin and the like.

Among these, it is preferable to contain chemical pulp such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood bleached sulphite pulp (LBSP), and softwood bleached sulphite pulp (NBSP).

The paper substrate 10 may contain, for example, a sizing agent (alkyl ketendimer-based, alkenyl anhydride-based succinic acid-based, higher fatty acid-based, petroleum resin-based, rosin-based, etc.) as long as the effects of the present embodiment are not impaired. Others such as paper strength enhancer (starch, polyacrylamide, polyamideamine-epichlorohydrin, etc.), yield improver, drainage improver, sulfuric acid band, pH adjuster, defoamer, pitch control agent, slime control agent, etc. Additives can be appropriately selected and used as needed.

The basis weight of the paper base material 10 is preferably 20 to 150 g / m ² . The lower limit of the basis weight is more preferably 25 g / m ² or more, further preferably 30 g / m ² or more, and even more preferably 35 g / m ² or more. Further, the upper limit of the basis weight is more preferably 80 g / m ² or less, further preferably 70 g / m ² or less, and further preferably 60 g / m ² or less. This basis weight is a numerical value measured based on the test method of basis weight of JIS P 8124: 2011. If the lower limit of the basis weight is within such a range, the strength of the oil-resistant paper is further improved, and if the upper limit value of the basis weight is within such a range, the cost does not increase.

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

As a method for producing the paper base material 10, a known method can be used. For example, softwood pulp and hardwood pulp are dispersed in water at a predetermined mass ratio, and the pulp slurry is beaten to a predetermined degree of beating with a beating machine to obtain a pulp slurry. Then, an additive or the like is added to the obtained pulp slurry, if desired. The prepared slurry can be made into a paper using a known paper machine such as a long net paper machine, a circular net paper machine, and a twin wire paper machine to obtain a paper base material 10. The papermaking method is not particularly limited, and either acidic papermaking or neutral papermaking can be selected.

As a method for forming the intermediate layer 20, an external addition method in which the paper substrate 10 is applied and / or impregnated after papermaking is preferable. For example, the coating liquid for forming the intermediate layer 20 is an aqueous dispersion having a solid content concentration of 0.01 to 30% by mass, and a bar coater, a die coater, a gravure coater, a roll coater, etc. The intermediate layer 20 can be formed by using a coating machine such as a blade coater, an air knife coater, and a size press coater. An air knife coater or a size press coater is preferable because the components of the intermediate layer 20 can be easily localized near the surface layer of the paper substrate 10.

As a method for forming the surface layer 30, the external addition method is preferable as in the intermediate layer 20, for example, the coating liquid for forming the surface layer 30 is an aqueous dispersion having a solid content concentration of 0.01 to 10% by mass, and at least. The surface layer 30 can be formed on the surface having the intermediate layer 20 by using a coating machine such as a bar coater, a die coater, a gravure coater, a roll coater, a blade coater, an air knife coater, and a size press coater. A bar coater or an air knife coater is preferable because it facilitates the formation of a uniform coating film.

Further, after the coating, the oil-resistant paper may be subjected to calendar processing using a calendar device such as a machine calendar, a thermal calendar, a super calendar, or a soft calendar.

The paper thickness of the oil-resistant paper 1 is preferably 20 to 150 μm. The lower limit of this thickness is more preferably 30 μm or more, further preferably 35 μm or more, and even more preferably 40 μm or more. Further, the upper limit of the thickness is more preferably 100 μm or less, further preferably 80 μm or less, and further preferably 70 μm or less. Within such a range, sufficient strength and oil resistance can be imparted for use as a base material for food packaging.

(Oil resistance)
The oil resistance of the oil-resistant paper with the surface of the surface layer 30 as the measurement surface was determined by the JAPAN TAPPI pulp and paper test method No. It is a kit value measured according to 41: 2000, and is preferably 5 or more. When the kit value of the oil-resistant paper 1 having the configuration of the present embodiment is 5 or more, sufficient oil resistance (particularly practical oil resistance) can be exhibited as the oil-resistant paper used in a standard environment.

(Practical oil resistance)
In the present embodiment, the practical oil resistance means that when the edible oil actually used is dropped on the surface layer of the oil-resistant paper, it is difficult for oil stains to permeate into the inside from the surface layer and appear. The specific evaluation method of practical oil resistance is as described in Examples described later.

(Inhibitory of dew condensation)
In the present embodiment, the inhibitory property of dew condensation indicates the degree of oil resistance when the oil resistant paper is exposed to high humidity. For example, when food such as french fries is put in a bag made of oil-resistant paper and the food is reheated in a microwave oven, the water vapor generated from the food condenses and the pulp of the oil-resistant paper is bonded. It will loosen and the oil in the food will easily leak to the outside of the bag. That is, it can be said that the oil-resistant paper having a high dew condensation suppressing property that allows water vapor to permeate from the inside of the bag to the outside is excellent in the difficulty of passing oil. The specific evaluation method of the inhibitory property of dew condensation is as described in Examples described later.

(Air permeability)
The air permeability of the oil-resistant paper 1 with the surface of the surface layer 30 as the measurement surface was determined by the JAPAN TAPPI pulp and paper test method No. 5-2: The Oken-type air permeability measured according to 2000, preferably 2000 to 100,000 seconds or less. This upper limit is more preferably 80,000 seconds or less, further preferably 70,000 seconds or less, and even more preferably 60,000 seconds or less. Further, this lower limit value is more preferably 3000 seconds or more, further preferably 5000 seconds or more, and even more preferably 10000 seconds or more. According to this embodiment, since the Oken-type air permeability can be set to the above upper limit or less, the air permeability of the oil-resistant paper is high enough to withstand a practical level, and the flavor and storage stability of food are deteriorated. It can be effectively prevented.

FIG. 2 is a schematic cross-sectional view of the oil-resistant paper according to the second embodiment.

The oil-resistant paper 2 according to the present embodiment is different from the oil-resistant paper 1 shown in FIG. 1 in that the intermediate layers 20 and 40 are provided on both sides of the paper base material 10. As described above, according to the present embodiment, the intermediate layer 20 (for example, in the case of a packaging bag for food or the like, the inner surface side for wrapping the food) and the intermediate layer 40 (for example, the packaging for food or the like) are placed on both sides of the paper base material 10. In the case of a bag, the outer surface side) may be provided. The intermediate layer 40 can be formed by the same method as the method for forming the intermediate layer 20 described above.

When the intermediate layers 20 and 40 are provided on both sides of the paper base material 10, the total amount of polyvinyl alcohol dried and adhered to the intermediate layers 20 and 40 on both sides of the paper base material 10 is 0.4 to 1.2 g / g. It is preferably m ² . The total amount of dry adhesion is the amount of dry adhesion of polyvinyl alcohol in the entire 1 m ² of the paper substrate 10, and refers to the amount of dry adhesion on both sides thereof. That is, in the case of the paper base material 10, it means the total of the dry adhesion amount of polyvinyl alcohol in the intermediate layer 20 and the dry adhesion amount of polyvinyl alcohol in the intermediate layer 40. The lower limit of this total amount is more preferably 0.45 g / m ² or more, further preferably 0.55 g / m ² or more, and even more preferably 0.6 g / m ² or more. Further, the upper limit of the total amount is more preferably 1.1 g / m ² or less, further preferably 1.0 g / m ² or less, and further preferably 0.9 g / m ² or less. ..

FIG. 3 is a schematic cross-sectional view of the oil-resistant paper according to the third embodiment.

In the oil-resistant paper 3 according to the present embodiment, the intermediate layers 20 and 40 are provided on both sides of the paper base material 10, and the surface layers 30 and 50 are also provided on both sides of the paper base material 10. It is different from the oil resistant paper 1 shown in. That is, the oil-resistant paper 3 is an embodiment in which the surface layer 50 is further provided on the surface of the intermediate layer 40 of the oil-resistant paper 2 shown in FIG.

As described above, in the present embodiment, the surface layers 30 and 50 may be provided on both sides of the paper base material 10 via the intermediate layers 20 and 40. For example, in the case of a packaging bag for food or the like, the surface layer 30 is on the inner surface side for wrapping food, and the surface layer 50 is on the outer surface side. The surface layer 50 can be formed by the same method as the method for forming the surface layer 30 described above. The surface layer 50 may have the same material, dimensions, shape, and the like as the surface layer 30, or may be different from the surface layer 30.

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to the following examples. In addition,% and a part represent a mass% and a mass part unless otherwise specified.

<Example 1>

(Preparation of paper substrate 10)

Pulp composed of 25% by mass of softwood bleached kraft pulp (NBKP) and 75% by mass of hardwood bleached kraft pulp (LBKP) is beaten so that the beating degree by the shopper rigger method is 55 ° SR, and the concentration of the pulp slurry is increased. Was dispersed in water so as to be about 2.7% by mass to obtain a pulp slurry.

2.0 parts by mass of sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd., trade name: size pine N-775) and starch (manufactured by GSL Japan Co., Ltd.) for 100 parts by mass of the pulp in this pulp slurry. Name: Geltron 245) by 1.0 part by mass, Wetting Paper Power Agent (manufactured by Seikou PMC, trade name: Paper Power WS-4020) by 1.3 parts by mass, Aluminum Sulfate (manufactured by Asahi Chemical Industry Co., Ltd., liquid sulfuric acid) Band) was added in an amount of 4.0 parts by mass, and glassin paper having a thickness of 60 μm and a basis weight of 40 g / m ² was made using a long net multi-cylinder paper machine to prepare a paper base material 10.

(Formation of intermediate layers 20 and 40)

4.0 parts by mass of modified polyvinyl alcohol (PVA, manufactured by Mitsubishi Chemical Co., Ltd., trade name: Gosenol T-350, saponification degree 93 to 95 mol%) was applied to both the front and back surfaces of the obtained paper substrate 10 by a size press. And the coating liquid for the intermediate layer (coating liquid for the intermediate layer) containing 96.0 parts by mass of water, the total amount of coating (wet adhesion amount) on both sides of the paper substrate 10 is 20 g / m ² . It was applied to the paper base material 10 so as to be. The total amount of the dry adhesion (dry adhesion amount) of the polyvinyl alcohol combined on both sides was 0.8 g / m ² (the dry adhesion amount on one side was 0.4 g / m ² ).

(Formation of surface layer 30)

Subsequently, using an air knife of a paper machine, 12 parts by mass of a styrene-acrylic copolymer resin (manufactured by Henkel Japan Ltd., trade name: AQUENCE EPIX BC-900F) and an olefin-based sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd.) as a sizing agent. , Product name: Polymaron LM-25S) in 12 parts by mass and 76 parts by mass of water for the surface layer coating liquid (surface layer coating liquid) so that the coating amount is 20 g / m ² . , Was applied to one surface of the intermediate layer 20 of the paper substrate 10. At this time, the total amount of dry adhesion of the styrene-acrylic copolymer resin and the sizing agent was 4.8 g / m ² . Then, a calendar process was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper 2 (sample) having the configuration shown in FIG. 2 was obtained.

<Example 2>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Then, using an air knife of a paper machine, add 12 parts by mass of styrene-acrylic copolymer resin (manufactured by Henkel Japan Ltd., trade name: AQUENCE EPIX BC-900F), and as a sizing agent, an alkyl ketene dimer-based sizing agent (Arakawa Chemical Industry Co., Ltd.). The intermediate layer 20 of the paper substrate 10 is coated with a coating liquid for a surface layer containing 12 parts by mass of SKS-L20) and 76 parts by mass of water so that the coating amount is 20 g / m ² . It was applied to one side. At this time, the total amount of dry adhesion of the styrene-acrylic copolymer resin and the sizing agent was 4.8 g / m ² . Then, a calendar process was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper 2 (sample) having the configuration shown in FIG. 2 was obtained.

<Example 3>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Subsequently, using an air knife of a paper machine, 12 parts by mass of a styrene-acrylic copolymer resin (manufactured by Henkel Japan Ltd., trade name: AQUENCE EPIX BC-900F) and a rosin-based sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd.) as a sizing agent. , Trade name: Size Pine N-775) in 12 parts by mass and 76 parts by mass of water in the coating liquid for the surface layer, so that the coating amount is 20 g / m ² , the intermediate layer of the paper substrate 10. It was applied to one side of 20. At this time, the total amount of dry adhesion of the styrene-acrylic copolymer resin and the sizing agent was 4.8 g / m ² . Then, a calendar process was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper 2 (sample) having the configuration shown in FIG. 2 was obtained.

<Example 4>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Subsequently, using an air knife of a paper making machine, 9 parts by mass of a styrene-acrylic copolymer resin (manufactured by Henkel Japan Ltd., trade name: AQUENCE EPIX BC-900F) and an olefin-based sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd.) as a sizing agent. , Trade name: Polymaron LM-25S) 15 parts by mass and 76 parts by mass of water for the surface layer coating liquid, so that the coating amount is 20 g / m ² , the intermediate layer 20 of the paper substrate 10 It was applied to one side. At this time, the total amount of dry adhesion of the styrene-acrylic copolymer resin and the sizing agent was 4.8 g / m ² . Then, a calendar process was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper 2 (sample) having the configuration shown in FIG. 2 was obtained.

<Example 5>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Subsequently, using an air knife of a paper making machine, 15 parts by mass of a styrene-acrylic copolymer resin (manufactured by Henkel Japan Ltd., trade name: AQUENCE EPIX BC-900F) and an olefin-based sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd.) as a sizing agent. , Trade name: Polymaron LM-25S) 9 parts by mass and 76 parts by mass of water for the surface layer coating liquid, so that the coating amount is 20 g / m ² , the intermediate layer 20 of the paper substrate 10 It was applied to one side. At this time, the total amount of dry adhesion of the styrene-acrylic copolymer resin and the sizing agent was 4.8 g / m ² . Then, a calendar process was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper 2 (sample) having the configuration shown in FIG. 2 was obtained.

<Example 6>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Subsequently, using an air knife of a paper making machine, 8 parts by mass of a styrene-acrylic copolymer resin (manufactured by Henkel Japan Ltd., trade name: AQUENCE EPIX BC-900F) and an olefin-based sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd.) as a sizing agent. , Trade name: Polymaron LM-25S) 8 parts by mass and 84 parts by mass of water for the surface layer coating liquid, so that the coating amount is 20 g / m ² , the intermediate layer 20 of the paper substrate 10 It was applied to one side. At this time, the total amount of dry adhesion of the styrene-acrylic copolymer resin and the sizing agent was 3.2 g / m ² . Then, a calendar process was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper 2 (sample) having the configuration shown in FIG. 2 was obtained.

<Comparative Example 1>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of surface layer 30)
The surface layer 30 was formed directly on the surface of the paper base material 10 without performing size pressing on the obtained paper base material 10. Specifically, the coating liquid for the surface layer used in Example 1 was prepared. Then, the surface layer 30 was formed by applying the coating liquid for the surface layer to one side of the paper base material 10 so that the coating amount of the coating liquid for the surface layer was 20 g / m ² without providing the intermediate layers 20 and 40. At this time, the total amount of dry adhesion of the styrene-acrylic copolymer resin and the sizing agent was 4.8 g / m ² . Then, a calendar treatment was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper (sample) was obtained.

<Comparative Example 2>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Subsequently, the surface layer coating liquid was applied to one surface of the intermediate layer 20 of the paper substrate 10 by the same method as in Example 1 except that the surface layer coating liquid to which no sizing agent was added was prescribed. .. At this time, the dry adhesion amount of the styrene-acrylic copolymer resin was 4.8 g / m ² . Then, a calendar treatment was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper (sample) was obtained.

<Comparative Example 3>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Subsequently, using an air knife of a paper machine, 12 parts by mass of a styrene-butadiene copolymer resin (manufactured by Nippon A & L Inc., trade name: Latex SN-309R) and an olefin-based sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd.) as a sizing agent. A coating liquid for a surface layer containing 12 parts by mass of Polymaron LM-25S) and 76 parts by mass of water is applied to the intermediate layer 20 of the paper substrate 10 so that the coating amount is 20 g / m ² . It was applied to one side. At this time, the total amount of dry adhesion between the styrene-butadiene copolymer resin and the sizing agent was 4.8 g / m ² . Then, a calendar treatment was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper (sample) was obtained.

<Comparative Example 4>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1 except that a sizing agent was not used in the formulation of the pulp slurry.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
The coating liquid for the surface layer used in Comparative Example 3 was prepared, and this was applied to one surface of the intermediate layer 20 of the paper substrate 10 by the same method as in Comparative Example 3. At this time, the total amount of dry adhesion between the styrene-butadiene copolymer resin and the sizing agent was 4.8 g / m ² . Then, a calendar treatment was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper (sample) was obtained.

<Comparative Example 5>

(Preparation of paper substrate 10)
A paper base material 10 was obtained in the same manner as in Comparative Example 4.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Subsequently, a surface layer coating liquid was prepared by the same method as in Comparative Example 4 except that a surface layer coating liquid to which a sizing agent was not added was prescribed, and this was applied to one surface of the intermediate layer 20 of the paper substrate 10. Was applied to. At this time, the dry adhesion amount of the styrene-butadiene copolymer resin was 4.8 g / m ² . Then, a calendar treatment was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper (sample) was obtained.

<Comparative Example 6>

(Preparation of paper substrate 10)
A paper substrate 10 was obtained in the same manner as in Example 1.

(Formation of intermediate layers 20 and 40)
Intermediate layers 20 and 40 were provided on both sides of the paper substrate 10 in the same manner as in Example 1.

(Formation of surface layer 30)
Subsequently, with an air knife of a paper machine, no resin (see "resin (a)" in Table 1) was added, and an olefin-based sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd., trade name: Polymaron LM-25S) was used as a sizing agent. ) Was applied to one surface of the intermediate layer 20 of the paper substrate 10 so that the coating amount was 20 g / m ² and the coating liquid for the surface layer containing 24 parts by mass and 76 parts by mass of water was applied. At this time, the total amount of dry adhesion between the resin and the sizing agent was 4.8 g / m ² . Then, a calendar treatment was performed so that the thickness of the paper was 55 μm, and an oil-resistant paper (sample) was obtained.

<Evaluation method>

The physical characteristics of each of the obtained oil-resistant papers were evaluated according to the method shown below.

(Air permeability)
The air permeability of the oil-resistant paper with the surface of the surface layer 30 as the measurement surface was determined by the JAPAN TAPPI pulp and paper test method No. The Oken type air permeability was measured according to 5-2: 2000.

(Humidity permeability)
Moisture permeability was measured according to JIS Z 0208: 1976.

(Oil resistance)
The oil resistance of the oil-resistant paper with the surface of the surface layer 30 as the measurement surface was determined by the JAPAN TAPPI pulp and paper test method No. It was measured according to 41: 2000.

(Practical oil resistance)
Using the surface of each of the obtained oil-resistant papers as the measurement surface, edible oil (manufactured by Nisshin Oillio Co., Ltd., trade name "Canola oil") was dropped onto the measurement surface, and after 30 minutes at room temperature, the edible oil permeated the measurement surface. The traces of the oil were visually confirmed.
〇: No trace of edible oil permeation was confirmed even after wiping the measurement surface.
X: Traces (oil stains) of edible oil permeating the measurement surface were confirmed.

(Inhibitory of dew condensation)
-Preparation of bags Each of the obtained oil-resistant papers was processed into a gussetless bag shape. The size of the bag was 120 mm in width × 90 mm in length, and the left and right ends were glued so that only the upper end of the bag was open.
-Conditions for adding moisture and judgment criteria 70 g of potato fries cooked with oil was put into the bag as a paper sample after bag making. Heat treatment was performed at 500 W in a microwave oven for 30 seconds. After observing the adhesion of droplets consisting of oil droplets or water droplets on the inner surface of the heat-treated bag and storing at room temperature for 30 minutes, if these droplets disappear, the droplets generated in the bag Was a water droplet, and it was judged that the water vapor permeability was poor. Further, when the droplets remained, it was judged that the droplets generated in the bag were oil components and there was no problem in water vapor permeability.
◯: No water droplets adhered to the inside of the bag.
X: Water droplets had adhered to the inside of the bag.

The manufacturing conditions and evaluation results of each Example and each Comparative Example are shown in Tables 1 and 2. The "dry adhesion amount (both sides)" of the intermediate layer in the table is the total dry adhesion amount of both the intermediate layer 20 and the intermediate layer 40 of the paper substrate 10. The amount of dry adhesion on one side of the intermediate layer 20 or the intermediate layer 40 is ½ of this value. For example, when the "dry adhesion amount (both sides)" of the intermediate layer in Table 1 is 0.8 g / m ² , the total dry adhesion amount of both the intermediate layer 20 and the intermediate layer 40 is 0.8 g / m. ^The amount of dry adhesion on one side of the intermediate layer or the intermediate layer 40 is 0.4 g / m ² . The "total ((a) + (b)) dry adhesion amount" of the surface layer in the table is the total of the dry adhesion amounts of the resin (a) and the sizing agent (b).

From the above, it was confirmed at least that according to the present embodiment, the oil-resistant paper having both high oil resistance and high air permeability is provided. Furthermore, it was also confirmed that such an excellent effect can be obtained even with a non-fluorine-based resin-based oil-resistant paper that does not contain a fluorine-based resin as in this example.

1,2,3: Oil resistant paper 10: Paper base material 20, 40: Intermediate layer 30, 50: Surface layer

Claims (9)

An oil-resistant paper containing a paper base material, an intermediate layer, and a surface layer.
The intermediate layer is provided on at least one surface of the paper substrate.
The surface layer is provided on the surface of the intermediate layer on the side opposite to the side on which the paper substrate is provided.
The intermediate layer contains polyvinyl alcohol and
The surface layer contains a styrene- (meth) acrylic copolymer resin and a sizing agent.
Oil resistant paper. The sizing agent comprises at least one selected from the group consisting of olefin-based sizing agents, rosin-based sizing agents, and alkylketene dimer-based sizing agents.
The oil-resistant paper according to claim 1. The dry adhesion amount of the polyvinyl alcohol in the intermediate layer is 0.2 to 0.6 g / m ² .
The oil-resistant paper according to claim 1 or 2. The intermediate layer is provided on both sides of the paper substrate.
The oil-resistant paper according to claim 1 or 2. The intermediate layer is provided on both sides of the paper substrate, and the intermediate layer is provided on both sides of the paper substrate.
The total amount of the polyvinyl alcohol adhered to the intermediate layer on both sides is 0.4 to 1.2 g / m ² .
The oil-resistant paper according to claim 4. The surface layer is provided on both sides of the paper substrate via the intermediate layer.
The oil-resistant paper according to claim 4 or 5. The dry adhesion amount of the styrene- (meth) acrylic copolymer resin on the surface layer is 1.2 to 3.6 g / m ² per one side of the paper substrate.
The oil-resistant paper according to any one of claims 1 to 6. The content of the sizing agent in the surface layer is 25 to 75% by mass in terms of solid content.
The oil-resistant paper according to any one of claims 1 to 7. The Oken-type air permeability of the oil-resistant paper in the JAPAN TAPPI pulp and paper test method is 2000 to 80,000 seconds.
The oil-resistant paper according to any one of claims 1 to 8.

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