Wrapping paper

Abstract

To provide a packaging paper sheet in which a used amount of plastics is reduced.SOLUTION: In a packaging paper sheet having at least one heat seal layer on at least one surface of a paper base material, the heat seal layer contains ionomer. A dry coating amount of the heat seal layer is in a range of 2 to 10 g / m2 in the whole layer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to packaging paper with reduced plastic usage.

Background Art

[0002] In recent years, the problem of plastic waste has been worsening. It is said that the world's plastic production exceeds 400 million tons per year, and among them, the plastic production in the packaging container sector is large, which has caused plastic waste. Plastic does not decompose semi-permanently, and this waste becomes microplastics in the natural environment, having a serious adverse impact on the ecosystem. As plastics used in packaging containers, polyethylene terephthalate (PET) used in beverage bottles etc., plastic shopping bags, polyethylene (PE) and polypropylene (PP) used in container laminates are most widely used. Especially, marine pollution is remarkable, and this plastic waste is said to be unrecoverable. In the future, it is necessary for the global environment to reduce the use of plastic.

[0003] On the other hand, as a measure against plastic waste, the application of biodegradable plastics that can be completely decomposed by microorganisms has been proposed worldwide. Although biodegradable plastics are decomposed in nature within a certain period, they are still waste until they are decomposed, and as long as their usage and waste amount are not reduced, it cannot be said to be an immediate measure (see Patent Documents 1 and 2).

[0004] As an immediate countermeasure, it has been proposed to replace plastic with paper. However, when processing paper into bags or containers, a large amount of polyethylene or polypropylene is laminated and used as a heat-sealing agent. The amount of lamination of these plastics varies depending on the product concept, but is generally 20 - 50 g / m 2 and is 300 g / m 2In some cases, it may also increase in large quantities. Therefore, even in packaging containers where plastic is replaced with paper, there is still a problem that the amount of plastic used is not sufficiently reduced, and there is an urgent need for a means to directly reduce the use of plastic.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide packaging paper capable of reducing the amount of plastic used.

Means for Solving the Problems

[0007] In the present invention, ionomer is used to reduce the amount of polyethylene or polypropylene used in the heat-sealing layer of conventional plastic laminate paper (hereinafter sometimes abbreviated as poly-laminated paper). That is, the packaging paper according to the present invention is a packaging paper having at least one heat-sealing layer on at least one surface of a paper substrate, the heat-sealing layer contains ionomer, and the coating amount of the heat-sealing layer is 2 to 10 g / m 2 It is characterized by being. The lamination amount of polyethylene or polypropylene used in the heat-sealing layer of conventional poly-laminated paper is 20 g / m 2Compared with exceeding this, the amount of plastic used for the heat-sealing layer can be reduced to about 10 to 50% of the conventional amount. Here, an ionomer is a synthetic resin in which polymers are aggregated using the cohesive force of metal ions, and is a synthetic resin obtained by combining acrylic acid or methacrylic acid with ethylene or the like. For example, it is produced by adding metal cations such as sodium or zinc to an acrylic polymer and ethylene and causing intermolecular bonding.

[0008] In the present invention, the heat-sealing layer may be formed in two or more layers on at least one surface. By adopting such a configuration, packaging paper with high air permeability, water repellency, and oil repellency can be obtained.

[0009] In the present invention, the air permeability of the packaging paper may exceed 10,000 seconds. By adopting such a configuration, the barrier property in terms of blocking air is enhanced, and furthermore, packaging paper with improved water repellency and oil repellency can be obtained.

[0010] In the present invention, the ionomer may be a metal salt of an ethylene-methacrylic acid copolymer. Packaging paper with excellent heat-sealing suitability can be obtained.

[0011] Further, the method for manufacturing the packaging paper in the present invention includes a step of preparing a coating liquid for the heat-sealing layer containing an ionomer emulsion, and applying the coating liquid for the heat-sealing layer to at least one surface of the paper base material in an amount of 2 to 10 g / m 2 in terms of solid content. In particular, by using an aqueous ionomer emulsion as the ionomer emulsion, the coating amount can be controlled relatively low, and since there is no VOC emission, packaging paper with a small environmental load can be obtained.

[0012] In the present invention, it is also preferable to apply the coating liquid for the heat-sealing layer to the surface of the paper base material having a smoothness of 10 seconds or more. This is preferable because it is easier for the heat-sealing layer to form a uniform thin film layer without becoming island-shaped or net-shaped, the variation in heat-sealing strength is reduced, and as a result, the heat-sealing strength of the packaging paper is increased. Note that the heat-sealing strength is the most strongly required property when processing a packaging container using the packaging paper.

[0013] In the present invention, the ionomer emulsion may also be a self-emulsifying emulsion. It is possible to obtain packaging paper having a heat-sealing layer with a uniform film thickness even with a thin film.

Advantages of the Invention

[0014] According to the present invention, it is possible to manufacture packaging paper with a reduced amount of plastic used. For container products using the packaging paper of the present invention, even if they are inappropriately released as garbage into the natural environment, it is possible to reduce the adverse impact as plastic garbage on the natural environment, which helps to solve the plastic garbage problem. Note that the packaging paper in the present invention can be processed into various packaging containers such as bags, food cups for ice cream etc., drink cups for coffee etc., food containers and trays for hot snacks, boxes, cases, utensils, envelopes etc.

Modes for Carrying Out the Invention

[0015] Next, embodiments of the present invention will be shown and described in detail, but the present invention is not construed as being limited to these descriptions. As long as the effects of the present invention are achieved, the embodiments may be variously modified.

[0016] In this embodiment, an ionomer is a general term for synthetic resins in which polymers are aggregated by the cohesive force of metal ions, and is a resin obtained by combining acrylic acid or methacrylic acid with ethylene or the like. That is, metal salts of ethylene-methacrylic acid copolymers, metal salts of ethylene-acrylic copolymers, metal salts of ethylene-urethane copolymers, metal salts of ethylene-fluorine-based polymer copolymers, etc. are all called ionomers. Examples of the metal forming the salt include alkali metal ions and alkaline earth metal ions, specifically, ions of sodium, potassium, calcium, magnesium, zinc, etc. In the present invention, it is preferable that the ionomer is a self-emulsifying emulsion which is a metal salt of an ethylene-methacrylic acid copolymer. Even when the coating amount of the heat-sealing layer is relatively small, a heat-sealing layer having sufficient heat-sealing strength can be provided.

[0017] In this embodiment, a heat-sealing layer can be provided by applying a coating liquid for a heat-sealing layer containing an ionomer emulsion to at least one surface of a paper substrate and drying it. By using an ionomer emulsion, it is possible to control the coating amount relatively low, and further, by using an aqueous ionomer emulsion, VOC emissions can be eliminated and the load on the natural environment can be reduced. The coating amount of the heat-sealing layer is 2 to 10 g / m 2 in terms of solid content per side of the paper substrate, preferably 3 to 8 g / m 2 . If it is less than 2 g / m 2 , sufficient heat-sealing strength cannot be satisfied. Conversely, if it exceeds 10 g / m 2 , it is of excessive quality in terms of heat-sealing strength and the plastic reduction effect becomes poor. In the packaging paper of the present invention, the heat-sealing layer is usually provided not only on a part of the surface of the paper substrate but on the entire surface. That is, the heat-sealing layer is preferably provided so as to cover the entire surface of the paper substrate, rather than being provided only on the portions necessary for adhesion by heat-sealing, such as in a net shape, island shape, or linear shape.

[0018] In addition to the ionomer emulsion, various auxiliary agents may be added to the coating liquid for the heat-sealing layer. For example, viscosity modifiers, defoamers, leveling agents such as surfactants and alcohols, coloring pigments, coloring dyes, and the like. However, since the addition of these auxiliary agents tends to cause a decrease in heat-sealing strength, it is preferable to use a small amount when adding them. In the present embodiment, it is preferable that the coating liquid for the heat-sealing layer consists only of the ionomer emulsion.

[0019] The method of coating the coating liquid for the heat-sealing layer is not particularly limited, and generally used coating apparatuses can be used. For example, various known coating apparatuses such as an air knife coater, a blade coater, a gravure coater, a rod blade coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, a die slot coater, a champlex coater, a metering blade type size press coater, a short dwell coater, a spray coater, a gate roll coater, and a lip coater can be used.

[0020] In the present embodiment, it is preferable that the heat-sealing layer is formed of two or more layers. By making it two or more layers, the air permeability of the packaging paper can be increased, and furthermore, water repellency and oil repellency can be imparted, and characteristics similar to or close to those of plastic film laminated paper can be obtained. When the heat-sealing layer is two or more layers, it is preferable that the coating amount of the lowermost heat-sealing layer closest to the paper base material is larger than the total coating amount of the other heat-sealing layers. This is because the air permeability of the packaging paper can be further improved, and the water repellency and oil repellency can be further enhanced.

[0021] In this embodiment, it is preferable that the air permeability of the packaging paper exceeds 10,000 seconds. More preferably, it is 12,000 seconds or more, and still more preferably, it is 15,000 seconds or more. By setting the air permeability of the packaging paper to 10,000 seconds or more, the barrier property in terms of blocking air becomes higher, and the water repellency and oil repellency are further improved. The method for setting the air permeability of the packaging paper to 10,000 seconds or more is not particularly limited. For example, it can be achieved by using a paper base material with high air permeability. Furthermore, by increasing the smoothness of the surface to which the heat-seal coating liquid is applied, the air permeability of the packaging paper can also be increased. This is because in the heat-seal layer formed thereafter, pinholes, cracks, etc. can be further reduced. For example, by providing a pigment coating layer and then performing calender treatment or the like, the smoothness of the surface to which the heat-seal coating liquid is applied can be increased. In addition, applying two or more layers of the heat-seal layer also has the effect of increasing the air permeability. The two-layer application of the heat-seal layer is considered to increase the air permeability by the second coating layer (upper layer) provided on top of the first coating layer covering the fine pinholes and cracks existing in the first coating layer (lower layer). Also, increasing the coating amount of the heat-seal layer is effective in improving the air permeability. In terms of the film formation surface of the heat-seal layer, the air permeability is likely to be improved by setting the drying temperature after applying the heat-seal layer coating liquid to a temperature equal to or higher than the melting point of the ionomer.

[0022] In this embodiment, it is preferable that the smoothness of the surface of the paper substrate to which the heat-sealing coating liquid is applied is 10 seconds or more. More preferably, it is 20 seconds or more. When the smoothness of the paper substrate is higher, the film thickness of the heat-sealing layer provided by coating tends to be uniform (fine unevenness is less likely to occur), and as a result, variations in heat-sealing strength are less likely to occur, and uniform heat-sealing strength can be imparted on the plane. The method for increasing the smoothness of the paper substrate is not particularly limited, and examples include calendar treatment using known calendar devices such as a super calendar, a gloss calendar, a Schü nip calendar, and a soft calendar. Also, paper obtained by transferring the mirror surface of a Yankee dryer, such as one-sided glazed kraft paper, is suitable as a paper substrate with high smoothness. Although there may be pinholes or cracks that are not visible to the naked eye in the heat-sealing layer, if the degree is such, it does not adversely affect the heat-sealing property. Further, as long as the effects of the present invention are not impaired, a leveling agent for the purpose of preventing pinholes can also be added to the heat-sealing layer coating liquid.

[0023] The paper base material used in this embodiment is not particularly limited, and known paper base materials mainly composed of pulp can be used. As the pulp that is the main component of the paper base material, chemical pulps such as LBKP (bleached hardwood kraft pulp) and NBKP (bleached softwood kraft pulp), mechanical pulps such as GP (groundwood pulp), PGW (pressure groundwood pulp), RMP (refiner mechanical pulp), TMP (thermomechanical pulp), CTMP (chemi-thermomechanical pulp), CMP (chemi-mechanical pulp), CGP (chemiground pulp), wood pulps such as DIP (deinked pulp), and non-wood pulps such as kenaf, bagasse, bamboo, and cotton can be used. These can be used alone or mixed at any ratio. For example, as the pulp, 90 to 100 parts by mass of LBKP (bleached hardwood kraft pulp) can be used in the pulp. Further, synthetic fibers can be further blended within a range that does not impair the effects of the present invention. From the viewpoint of environmental protection, ECF (Elemental Chlorine Free) pulp, TCF (Total Chlorine Free) pulp, wastepaper pulp, and pulp obtained from planted forest trees are preferable. Also, for example, as an appropriate beating degree of the pulp, the Canadian standard drainage degree (freeness) (JIS P 8121:1995 "Test method for drainage degree of pulp") is 200 to 700 ml CSF, for example, 450 to 620 ml CSF.

[0024] As the paper base material, those containing a filler can also be used. Examples of the filler include light calcium carbonate, heavy calcium carbonate, talc, clay, kaolin, calcined clay, titanium dioxide, and aluminum hydroxide. The filler content in the paper base material is, for example, 1 to 30 parts by mass with respect to 100 parts by mass of the dry mass of the pulp. For example, it is preferable to contain 1 to 10 parts by mass of light calcium carbonate with respect to 100 parts by mass of the dry mass of the pulp.

[0025] In addition to pulp and fillers, the paper base material may contain various known papermaking additives. Examples of papermaking additives include internal paper strength enhancers such as sizing agents and wet paper strength enhancers, bulking agents, yield improvers, drainage improvers, coloring dyes, coloring pigments, fluorescent brighteners, fluorescent decolorizing agents, pitch control agents, etc. Further, water-soluble polymers such as starch, polyvinyl alcohol, and polyacrylamide may be applied.

[0026] The papermaking method of the paper base material is not particularly limited and can be manufactured by various papermaking machines such as a Fourdrinier paper machine, a Fourdrinier multi-layer paper machine, a cylinder paper machine, a cylinder multi-layer paper machine, a Fourdrinier-cylinder combined multi-layer paper machine, and a twin-wire paper machine. Further, in the present invention, the paper base material may be single-layered, multi-layered, or a laminated product of a plurality of layers.

[0027] The paper substrate may be provided with one or more coating layers other than the heat-sealing layer. For example, it may be provided with a pigment coating layer containing a pigment and an adhesive. As the pigment in the pigment coating layer, known pigments used in the coating layer of general printing coated paper can be used. For example, calcium carbonate (such as heavy calcium carbonate and light calcium carbonate), kaolin (including clay), calcined clay, talc, magnesium carbonate, barium sulfate, calcium sulfate, titanium dioxide, zinc oxide, zinc sulfate, zinc carbonate, calcium silicate, aluminum silicate, magnesium silicate, diatomaceous earth, aluminum hydroxide, magnesium hydroxide and other inorganic pigments, or acrylic, styrene, vinyl chloride, nylon itself, and organic pigments obtained by copolymerizing these (so-called plastic pigments) can be mentioned. For example, as the pigment, a combination of 20 to 40 parts by mass of kaolin and 60 to 80 parts by mass of heavy calcium carbonate can be used. Also, as the adhesive, known adhesives used in the coating layer of general printing coated paper can be used. For example, butadiene-based copolymer latex, cross-linked modified starch, oxidized starch, enzyme-modified starch, esterified starch, etherified starch, cationic starch, amphoteric starch and other starches, gelatin, casein, soy protein, water-soluble polymers such as polyvinyl alcohol, vinyl acetate, ethylene vinyl acetate, polyurethane-based resins, acrylic-based resins, polyester-based resins, polyamide-based resins, and other synthetic resins can be exemplified. The blending ratio of the pigment and the adhesive in the pigment coating layer is not particularly limited, but it is preferably 5 to 50 parts by mass of the adhesive with respect to 100 parts by mass of the pigment. For example, as the adhesive, a combination of 1 to 5 parts by mass of phosphate esterified starch and 5 to 15 parts by mass of styrene butadiene latex can be used with respect to 100 parts by mass of the pigment. The pigment coating layer may contain various auxiliaries as long as the effects of the present invention are not impaired. For example, viscosity regulators, softeners, gloss imparting agents, water resistance agents, dispersants, flow modifiers, ultraviolet absorbers, stabilizers, antistatic agents, cross-linking agents, sizing agents, fluorescent brighteners, colorants, pH regulators, defoamers, plasticizers, preservatives may be included. Also, as the coating amount of such a pigment coating layer, for example, per one side of the base paper, in terms of solid content, 2 to 40 g / m 2That is. As one embodiment of the packaging paper of the present invention, the heat-sealing layer may be provided on such a pigment coating layer. As another embodiment, the heat-sealing layer may be provided on the surface of the paper base material provided with the pigment coating layer on only one side, on the surface where the pigment coating layer is not provided.

[0028] In this embodiment, the basis weight of the packaging paper is not particularly limited. For example, it is 10 to 1000 g / m 2 That is. As the basis weight of the packaging paper that is highly barrier, water-repellent, and oil-repellent and can also be used for flexible packaging, 30 to 500 g / m 2 is preferable, and 50 to 300 g / m 2 is more preferable.

Examples

[0029] Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, "parts" and "%" in the examples indicate "parts by mass" and "mass %", respectively, unless otherwise specified. The number of added parts is the value in terms of solid content.

[0030] (Example 1) (Production of base paper) 100 parts of Canadian Standard Freeness 520 ml csf hardwood bleached kraft pulp, 5 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.2 part of cationized starch (trade name: Neo Tack 30T, manufactured by Nippon Food Processing Co., Ltd.), and 0.2 part of neutral rosin size (trade name: CC167, manufactured by Starlight PMC Co., Ltd.) were mixed with water to prepare a paper stock, and a base paper with a basis weight of 58 g / m 2 was produced using a Fourdrinier multi-cylinder paper machine. This base paper was coated with oxidized starch (trade name: MS3800, manufactured by Nippon Food Chemical Co., Ltd.) on both sides with a dry coating amount of 2 g / m 2 per side, and dried to obtain a base paper of 60 g / m 2 .

[0031] (Preparation of coating liquid for pigment coating layer) 30 parts of kaolin (trade name: Contour 1500, manufactured by Imerys) and 70 parts of heavy calcium carbonate (trade name: Carbilux, manufactured by Imerys) were added with 0.2 parts of a dispersant (trade name: Aron T-50, manufactured by Toagosei Co., Ltd.), and water was added and water-dispersed using a Cowles disperser to prepare a pigment slurry. To this pigment slurry, 2 parts of a phosphate esterified starch (trade name: MS4600, manufactured by Nippon Shokuhin Kako Co., Ltd.) and 8 parts of a styrene-butadiene latex (trade name: PA0372, manufactured by Japan A&R Co., Ltd.) as binders, and further water was added and dispersed to prepare a coating liquid for a pigment coating layer with a solid content concentration of 50%.

[0032] (Production of paper base material) On both sides of the base paper obtained above, the coating liquid for the pigment coating layer was coated and dried using a blade coater so that the dry coating amount per side was 10 g / m 2 . Then, calendering treatment was performed to produce a paper base material (coated paper) with a basis weight of 80 g / m 2 . The smoothness of the coated surface (the surface on which the heat seal layer is provided in the subsequent process) at this time was 400 seconds.

[0033] (Production of packaging paper) On one side of the paper base material obtained above, an aqueous ionomer emulsion (trade name: Chem Pearl S-300, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, average particle diameter by microtrack method 0.5 μm) was coated using an air knife coater so that the dry coating amount was 5 g / m 2 , dried to provide a heat seal layer, and packaging paper was produced.

[0034] (Example 2) In Example 1, packaging paper was produced in the same manner as in Example 1, except that the coating amount of the heat seal layer was changed to 10 g / m 2 .

[0035] (Example 3) In Example 1, packaging paper was produced in the same manner as in Example 1, except that the coating amount of the heat seal layer was changed to 9 g / m 2 .

[0036] (Example 4) In Example 1, except that the coating amount of the heat-sealing layer was changed to 2 g / m 2 the packaging paper was produced in the same manner as in Example 1.

[0037] (Example 5) In Example 1, except that the coating amount of the heat-sealing layer was changed to 3 g / m 2 the packaging paper was produced in the same manner as in Example 1.

[0038] (Example 6) A base paper was produced in the same manner as in Example 1. Next, the same coating liquid for the pigment coating layer as in Example 1 was applied to both sides as the lower layer with a gate roll coater at a dry coating amount of 10 g / m per side 2 Then, the same coating liquid for the coating layer as in Example 1 was applied to both sides as the upper layer with a blade coater at a dry coating amount of 10 g / m per side 2 and supercalendered to produce a paper base material (coated paper) with a basis weight of 100 g / m 2 The smoothness of the coated surface (the surface on which the heat-sealing layer is provided in the subsequent process) at this time was 2500 seconds. Next, a heat-sealing layer was provided on one side of the paper base material obtained above in the same manner as in Example 1 to produce a packaging paper.

[0039] ( Reference Example 7) (Production of Paper Base Material) 100 parts of broadleaf kraft pulp with a Canadian Standard Freeness of 580 ml csf, 5 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.2 parts of cationized starch (trade name: Neo Tack 30T, manufactured by Nippon Food Processing Co., Ltd.), and 0.2 parts of neutral rosin size (size pine NT-78: manufactured by Arakawa Chemical Industries, Ltd.) were mixed with water to prepare a paper stock, and a base paper with a basis weight of 188 g / m was produced using a Fourdrinier multi-cylinder paper machine 2 This base paper was coated on both sides by a size press with oxidized starch (trade name: MS3800, manufactured by Nippon Food Chemical Co., Ltd.) at a dry coating amount of 2 g / m per side 2 and dried to 190 g / m 2A paper substrate was obtained. The smoothness of the surface of this paper substrate (the surface on which the heat-sealing layer is provided in the subsequent process) was 10 seconds.

[0040] (Production of Packaging Paper) On one side of the paper substrate obtained above, an aqueous ionomer emulsion (trade name: Chem Pearl S-100, manufactured by Mitsui Chemicals, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, average particle diameter of 0.1 μm by Microtrac method) was applied by an air knife coater so that the dry coating amount was 6 g / m 2 and dried to provide a heat-sealing layer, thereby producing packaging paper.

[0041] ( Reference Example 8) Packaging paper was produced in the same manner as in Example 7, except that calendering was performed on the base paper after applying oxidized starch. The smoothness of the surface of the base paper (the surface on which the heat-sealing layer is provided in the subsequent process) at this time was 20 seconds. Reference

[0042] ( Reference Example 9) (Production of Paper Substrate) 100 parts of hardwood bleached kraft pulp with a Canadian Standard Freeness of 580 ml csf, 5 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.), 0.2 parts of cationized starch (trade name: Neo Tack 30T, manufactured by Nippon Shokuhin Kako Co., Ltd.), and 0.2 parts of neutral rosin size (size pine NT-78: manufactured by Arakawa Chemical Industries, Ltd.) were added with water to prepare a paper stock, and a base paper (three-layered) with a basis weight of 298 g / m was produced using a three-layer long wire multi-cylinder paper machine. On this base paper, oxidized starch (trade name: MS3800, manufactured by Nippon Shokuhin Kako Co., Ltd.) was applied by a size press so that the dry coating amount per side was 2 g / m 2 and dried and soft-calendered to obtain a paper substrate with a basis weight of 300 g / m 2 The smoothness of the surface of the paper substrate (the surface on which the heat-sealing layer is provided in the subsequent process) was 100 seconds. 2

[0043] (Production of Packaging Paper) On one side of the paper substrate obtained above, an aqueous ionomer emulsion (trade name: Chem Pearl S-500, manufactured by Mitsui Chemicals, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, average particle diameter 0.7 μm by Microtrac method) was applied using an air knife coater so that the dry coating amount was 4 g / m 2 and dried to provide a heat-sealing layer, thereby producing packaging paper.

[0044] (Example 10) Reference On one side of the paper substrate obtained in Example 9, a coating liquid for a pigment coating layer similar to that in Example 1 was applied using an air knife coater so that the dry coating amount was 20 g / m 2 and then soft-calendered to produce a paper substrate of 320 g / m 2 . The smoothness of the non-coated surface (the surface of the paper substrate where the pigment coating layer is not provided) of this paper substrate was 150 seconds. Next, a heat-sealing layer was provided on the non-coated surface of the paper substrate obtained above in the same manner as in Example 1, thereby producing packaging paper.

[0045] ( Reference (Example 11) Reference On one side of the paper substrate obtained in Example 9, an aqueous ionomer emulsion (trade name: Chem Pearl S-300, manufactured by Mitsui Chemicals, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, average particle diameter 0.5 μm by Microtrac method) was applied using an air knife coater so that the dry coating amount was 5 g / m 2 and dried to provide a heat-sealing layer (lower layer). Next, the same aqueous ionomer emulsion was applied on the surface of the heat-sealing layer (lower layer) using an air knife coater so that the dry coating amount was 2 g / m 2 and dried to provide a heat-sealing layer (upper layer), thereby producing packaging paper.

[0046] (Example 12) On the non-coated surface of the paper substrate produced in Example 10 (the surface where the pigment coating layer of the paper substrate is not provided), an aqueous ionomer emulsion (trade name: MYE-30ER, manufactured by Marubeni Chemical Co., composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, microtrack method average particle diameter 0.2 μm) was applied using an air knife coater so that the dry coating amount was 3 g / m 2 and dried to provide a heat-sealing layer (lower layer). Next, an aqueous ionomer emulsion (trade name: MYE-30MAZ, manufactured by Marubeni Chemical Co., composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, microtrack method average particle diameter 0.3 μm) was applied to the surface of the heat-sealing layer (lower layer) using an air knife coater so that the dry coating amount was 1 g / m 2 and dried to provide a heat-sealing layer (upper layer), thereby producing packaging paper.

[0047] (Example 13) On the non-coated surface of the paper substrate produced in Example 10 (the surface where the pigment coating layer of the paper substrate is not provided), an aqueous ionomer emulsion (trade name: ChemPearl S-300, manufactured by Mitsui Chemicals, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, microtrack method average particle diameter 0.5 μm) was applied using an air knife coater so that the dry coating amount was 5 g / m 2 and dried to provide a heat-sealing layer (lower layer). Next, the same aqueous ionomer emulsion was applied to the surface of the heat-sealing layer (lower layer) using an air knife coater so that the dry coating amount was 1 g / m 2 and dried to provide a heat-sealing layer (upper layer), thereby producing packaging paper.

[0048] (Example 14) On the non-coated surface of the paper substrate produced in Example 10 (the surface where the pigment coating layer of the paper substrate is not provided), an aqueous ionomer emulsion (trade name: ChemPearl S-300, manufactured by Mitsui Chemicals, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, microtrack method average particle diameter 0.5 μm) was applied using an air knife coater so that the dry coating amount was 1 g / m 2Coating was performed using an air knife coater so as to obtain [the desired state], followed by drying to provide a heat-sealing layer (lower layer). Next, the same aqueous ionomer emulsion was applied to the surface of the heat-sealing layer (lower layer) such that the dry coating amount was 9 g / m 2 Coating was performed using an air knife coater so as to obtain [the desired state], followed by drying to provide a heat-sealing layer (upper layer), and packaging paper was produced.

[0049] (Example 15) On the non-coated surface of the paper substrate produced in Example 10 (the surface on which the pigment coating layer of the paper substrate is not provided), an aqueous ionomer emulsion (trade name: Chem Pearl S-300, manufactured by Mitsui Chemicals, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, Microtrac method average particle diameter 0.5 μm) was applied using an air knife coater such that the dry coating amount was 9 g / m 2 Coating was performed using an air knife coater so as to obtain [the desired state], followed by drying to provide a heat-sealing layer (lower layer). Next, the same aqueous ionomer emulsion was applied to the surface of the heat-sealing layer (lower layer) such that the dry coating amount was 1 g / m 2 Coating was performed using an air knife coater so as to obtain [the desired state], followed by drying to provide a heat-sealing layer (upper layer), and packaging paper was produced.

[0050] ( Reference (Example 16) Reference On one side of the paper substrate produced in Example 7, an aqueous ionomer emulsion (trade name: Chem Pearl S-300, manufactured by Mitsui Chemicals, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, Microtrac method average particle diameter 0.5 μm) was applied using an air knife coater such that the dry coating amount was 5 g / m 2 Coating was performed using an air knife coater so as to obtain [the desired state], followed by drying to provide a heat-sealing layer (lower layer). Next, the same aqueous ionomer emulsion was applied to the surface of the heat-sealing layer (lower layer) such that the dry coating amount was 1 g / m 2 Coating was performed using an air knife coater so as to obtain [the desired state], followed by drying to provide a heat-sealing layer (upper layer), and packaging paper was produced.

[0051] ( Reference (Example 17) ReferenceOn both sides of the paper substrate prepared in Example 7, an aqueous ionomer emulsion (trade name: Chem Pearl S-300, manufactured by Mitsui Chemicals, composition: metal salt of ethylene-methacrylic acid copolymer, self-emulsifying emulsion, microtrack method average particle size 0.5 μm) was applied using an air knife coater so that the dry coating amount per side was 5 g / m 2 and dried to provide a heat seal layer (lower layer). Next, the same aqueous ionomer emulsion was applied to the surface of the heat seal layer (lower layer) on both sides of the upper substrate using an air knife coater so that the dry coating amount per side was 1 g / m 2 and dried to provide a heat seal layer (upper layer), thereby producing packaging paper.

[0052] (Comparative Example 1) On one side of the paper substrate prepared in Example 1, low-density polyethylene (manufactured by Tosoh Corporation, Petrothene DLZ19A) was laminated using an extrusion coater (melt extruder) so that the coating amount was 30 g / m 2 to provide a heat seal layer, thereby producing packaging paper.

[0053] (Comparative Example 2) On one side of the paper substrate prepared in Example 1, polypropylene (manufactured by Nippon Polypropylene Corporation, Novatec FL03H) was laminated using an extrusion coater (melt extruder) so that the coating amount was 30 g / m 2 to provide a heat seal layer, thereby producing packaging paper.

[0054] (Comparative Example 3) In Example 1, packaging paper was produced in the same manner as in Example 1, except that the aqueous ionomer emulsion was changed to an aqueous polyethylene emulsion (manufactured by San Nopco Ltd., SN Coat 287).

[0055] (Comparative Example 4) In Example 1, packaging paper was produced in the same manner as in Example 1, except that the aqueous ionomer emulsion was changed to an aqueous polypropylene emulsion (manufactured by Toho Chemical Industry Co., Ltd., High-Tech P-5300).

[0056] Each Example , Reference Example For the packaging papers obtained in each Example and Comparative Example, evaluation was carried out by the following method. The obtained results are shown in Tables 1 to 3. When there is only one heat-sealing layer, for the sake of convenience, the coating amount was described in the coating amount column of the upper layer of the heat-sealing layer.

[0057] (1) Smoothness In accordance with JIS P 8155:2010, using a digital-type Ono research air permeability and smoothness tester (manufactured by Asahi Seiko Co., Ltd., model number: EYDO-6-2M), the smoothness (seconds) of the surface of the paper substrate close to the heat-sealing layer (heat-sealing layer forming surface) before providing the heat-sealing layer was measured. A higher numerical value indicates that the surface of the paper substrate is smoother.

[0058] (2) Air Permeability In accordance with JIS P 8117:2009, using a digital-type Ono research air permeability and smoothness tester (manufactured by Asahi Seiko Co., Ltd., model number: EYDO-6-2M), the air permeability (seconds) of the packaging paper was measured. A higher numerical value indicates lower air permeability (higher barrier property).

[0059] (2) Heat-Sealing Strength The obtained packaging paper was cut into two pieces with a size of 8 mm in width and 15 cm in length. The front and back surfaces of the packaging paper were overlapped and heat-sealed with a heat-sealing device (manufactured by Parmec Co., Ltd., model number: PTS-100) under certain conditions (adhesion width: 4 mm, temperature: 180 °C, pressure 0.4 MPa, pressing time 0.5 seconds, pitch: 4 mm). Then, the heat-sealed sample was measured for peel strength with a peel strength tester (manufactured by Shimadzu Corporation, model number: Autograph AGS-X) under certain conditions (peel speed: 100 mm / min, peel length: 10 cm) to obtain the heat-sealing strength (gf / 4 mm). A higher numerical value indicates better performance. When both sides are heat-sealing layers, it refers to the adhesion strength between the heat-sealing layers.

[0060] (3) Water Repellency In accordance with JIS K 6768:1999 (Plastics - Films and Sheets - Test Method for Wettability Tension), the water repellency of the heat seal layer surface was evaluated. The lower the number, the higher the water repellency (the more difficult it is to get wet). When there are heat seal layers on both sides, the average value of both sides was used.

[0061] (4) Oil repellency In accordance with TAPPI T-559cm-02 (Kit Method), the oil repellency of the heat seal layer surface was evaluated. The higher the value (kit value), the higher the oil repellency. When there are heat seal layers on both sides, the average value of both sides was used.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] As is clear from Tables 1 to 3, the packaging paper according to the examples 1~6、10、12~15 had a heat seal strength equal to or higher than that of Comparative Examples 1 to 2, despite significantly reducing the amount of the heat seal layer. Also, it was clearly superior in heat seal strength compared to Comparative Examples 3 to 4. As the experimental results show, according to the present invention, it is possible to significantly reduce the amount of the heat seal layer used compared to the conventional polyethylene laminate amount, contribute to the reduction of plastic waste, and provide a packaging paper excellent in barrier properties, water repellency, and oil repellency.

Claims

1. A packaging paper consisting only of a paper substrate, a heat-sealing layer, and a pigment coating layer, wherein the heat-sealing layer is provided on one or more pigment coating layers, and having at least one heat-sealing layer on at least one surface of the paper substrate, the heat-sealing layer contains an ionomer, and the dry coating amount of the heat-sealing layer is 2 to 10 g / m ２ in total for all layers, and the ionomer is a metal salt of an ethylene-methacrylic acid copolymer.

2. A packaging paper consisting only of a paper substrate, a heat-sealing layer, and a pigment coating layer, having the pigment coating layer on only one surface of the paper substrate, and having the heat-sealing layer on the surface of the paper substrate where the pigment coating layer is not provided, wherein the heat-sealing layer contains an ionomer, and the dry coating amount of the heat-sealing layer is 2 to 10 g / m ２ for the entire layer, and the ionomer is a metal salt of an ethylene-methacrylic acid copolymer.

3. The packaging paper according to claim 1 or 2, characterized in that the heat-sealing layer is formed of two or more layers on at least one surface.

4. The packaging paper according to any one of claims 1 to 3, characterized in that the air permeability exceeds 10,000 seconds.

5. The packaging paper according to any one of claims 1 to 4, characterized in that the heat-sealing layer consists only of an ionomer.

6. The basis weight of the packaging paper is 10 to 1000 g / m ２ The packaging paper according to any one of claims 1 to 5, characterized in that it is so.

7. A pigment coating layer is coated on at least one surface of the paper base material, and then a step of preparing a coating liquid for the heat-sealing layer containing an aqueous ionomer emulsion is carried out, A step of coating at least one surface of the paper substrate with the coating liquid for the heat-sealing layer in a range of 2 to 10 g / m in terms of solid content, ２ and having, the ionomer in the aqueous ionomer emulsion is a metal salt of an ethylene-methacrylic acid copolymer, A method for manufacturing a packaging paper consisting only of a paper base material, a heat-sealing layer, and a pigment coating layer.

8. A pigment coating layer is coated on one surface of the paper base material, and then a step of preparing a coating liquid for the heat-sealing layer containing an aqueous ionomer emulsion is carried out, A step of applying the coating liquid for the heat-sealing layer in an amount of 2 to 10 g / m in terms of solid content on the surface of the base material layer where the pigment coating layer is not provided, ２ and having, the ionomer in the aqueous ionomer emulsion is a metal salt of an ethylene-methacrylic acid copolymer, A method for manufacturing a packaging paper consisting only of a paper base material, a heat-sealing layer, and a pigment coating layer.

9. The method for manufacturing a packaging paper according to claim 7 or 8, characterized in that the coating liquid for the heat-sealing layer is coated on the surface of the paper base material having a smoothness of 10 seconds or more.

10. The method for manufacturing a packaging paper according to any one of claims 7 to 9, characterized in that the aqueous ionomer emulsion is a self-emulsifying emulsion.

11. The method for manufacturing a packaging paper according to any one of claims 7 to 10, characterized in that the heat-sealing layer consists only of an ionomer.

12. The method for manufacturing a packaging paper according to any one of claims 7 to 11, characterized in that the heat-sealing layer is formed of two or more layers on at least one surface.

13. The basis weight of the packaging paper is 10 to 1000 g / m ２ The method for manufacturing the packaging paper according to any one of claims 7 to 12, characterized in that it is as such.

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