JPWO2020152753A1 - Wrapping paper - Google Patents

Abstract

An object of the present invention is to provide a wrapping paper in which the amount of plastic used is reduced. The present invention is a wrapping paper having at least one heat-sealing layer on at least one surface of a paper substrate, the heat-sealing layer containing an ionomer, and the dry coating amount of the heat-sealing layer is all layers. The present invention relates to a wrapping paper characterized by being 2 to 10 g / m2.

Description

The present invention relates to a wrapping paper in which the amount of plastic used is reduced.

In recent years, the plastic waste problem has become more serious. The world's plastic production is said to exceed 400 million tons / year, and among them, the packaging sector has a large amount of plastic production, which is a cause of plastic waste. Plastic does not decompose semi-permanently, and the waste becomes microplastic in the natural environment, which has a serious adverse effect on the ecosystem. The most commonly used plastics for packaging containers are polyethylene terephthalate (PET) used for beverage bottles and the like, polyethylene (PE) and polypropylene (PP) used for laminating cash register bags and containers. .. In particular, marine pollution is significant, and it is said that the plastic waste cannot be collected. In the future, it is necessary for the global environment to reduce the use of plastics.

On the other hand, applications of biodegradable plastics that can be completely decomposed by microorganisms have been proposed all over the world as a measure against plastic waste. Biodegradable plastics are decomposed in nature within a certain period of time, but until they are decomposed, they are still garbage, and unless their usage and disposal amount are reduced, it cannot be said to be an immediate measure ( See Patent Documents 1 and 2).

As a quick-acting countermeasure, it has been proposed to replace plastic with paper, but when processing paper into bags and containers, a large amount of polyethylene or polypropylene is laminated and used as a heat sealant. To. Laminates of these plastics, but different depending on the product concept, generally a 20 to 50 g / ^{m 2,} it may be extensive and 300 g / ^{m 2.} Therefore, even in a packaging container in which 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 for directly reducing the use of plastic.

Japanese Unexamined Patent Publication No. 2012-148444 Japanese Unexamined Patent Publication No. 2013-141763

An object of the present invention is to provide a wrapping paper capable of reducing the amount of plastic used.

In the present invention, an ionomer is used in order to reduce the amount of polyethylene or polypropylene used in the conventional plastic laminated paper (hereinafter sometimes abbreviated as polylami paper). That is, the wrapping paper according to the present invention is a wrapping paper having at least one heat-sealing layer on at least one surface of the paper base material, the heat-sealing layer contains an ionomer, and the amount of coating of the heat-sealing layer is large. It is characterized by being ² to 10 g / m ² . Compared to the amount of polyethylene or polypropylene laminated in the conventional heat seal layer of polylami paper exceeding 20 g / m ² , the amount of plastic used in the heat seal layer is up to about 10 to 50% of the conventional amount. It can be reduced. Here, the ionomer is a synthetic resin in which a polymer is made into an aggregate by utilizing the cohesive force of metal ions, and is a synthetic resin in which acrylic acid or methacrylic acid is combined with ethylene or the like. For example, it is produced by adding an acrylic polymer and ethylene to an intermolecular bond by adding a metal cation such as sodium or zinc.

In the present invention, the heat seal layer may be formed of two or more layers on at least one surface. With such a configuration, it is possible to obtain a wrapping paper having high air permeability and water repellency and oil repellency.

In the present invention, the air permeability of the wrapping paper may exceed 10,000 seconds. With such a configuration, it is possible to obtain a wrapping paper having a high barrier property in the sense of blocking air and also having improved water repellency and oil repellency.

In the present invention, the ionomer may be a metal salt of an ethylene / methacrylic acid copolymer. Excellent wrapping paper can be obtained due to its heat seal suitability.

Further, the method for producing a wrapping paper in the present invention includes a step of preparing a coating liquid for a heat seal layer containing an ionomer emulsion and a solid coating liquid for a heat seal layer on at least one surface of a paper substrate. It is characterized by having a step of coating in a range of ² to 10 g / m ^{2 in} terms of minutes. In particular, by using an aqueous ionomer emulsion as the ionomer emulsion, it is possible to control the coating amount to be relatively low, and since there is no VOC emission, it is possible to obtain a wrapping paper having a small environmental load.

Further, in the present invention, it is preferable to apply the coating liquid for the heat seal layer on the surface of the paper substrate having a smoothness of 10 seconds or more. It is preferable because the heat-sealing layer tends to be a uniform thin film film layer without being island-shaped or net-like, the variation in heat-sealing strength is reduced, and as a result, the heat-sealing strength of the wrapping paper is increased. The heat seal strength is the most strongly required characteristic when processing a packaging container using packaging paper.

Further, in the present invention, the ionomer emulsion may be a self-emulsifying emulsion. A wrapping paper having a heat-sealing layer having a uniform film thickness can be obtained even with a thin film.

According to the present invention, it is possible to produce a wrapping paper in which the amount of plastic used is reduced. With the container product using the wrapping paper of the present invention, even if it is inappropriately released as dust in the natural world, it is possible to reduce the adverse effect of plastic dust on the natural environment, and plastic. Helps solve the garbage problem. The wrapping paper in the present invention is processed into, for example, bags, food cups such as ice cream, beverage cups such as coffee, food containers such as hot snacks, and packaging containers such as trays, boxes, cases, vessels, and envelopes. It is possible.

Next, the present invention will be described in detail by showing embodiments, but the present invention is not construed as being limited to these descriptions. The embodiments may be modified in various ways as long as the effects of the present invention are exhibited.

In the present embodiment, ionomer is a general term for synthetic resins in which polymers are aggregates by utilizing the cohesive force of metal ions, and is a resin in which acrylic acid or methacrylic acid is combined with ethylene or the like. That is, a metal salt of an ethylene / methacrylic acid copolymer, a metal salt of an ethylene / acrylic copolymer, a metal salt of an ethylene / urethane copolymer, a metal salt of an ethylene / fluorine polymer copolymer, etc. All are called ionomers. Examples of the metal forming the salt include alkali metal ions and alkaline earth metal ions, specifically, sodium, potassium, calcium, magnesium, and zinc ions. 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. A heat seal layer having a sufficient heat seal strength can be provided with a relatively small amount of the heat seal layer applied.

In the present embodiment, the heat seal layer can be provided by applying a coating liquid for a heat seal layer containing an ionomer emulsion to at least one surface of a paper base material and drying it. By using the ionomer emulsion, the coating amount can be controlled to be relatively low, and by using the water-based ionomer emulsion, VOC emissions can be eliminated and the load on the natural environment can be reduced. The coating amount of the heat seal layer is ² to 10 g / m ² in terms of solid content, preferably 3 to 8 g / m ² per one side of the paper base material. If it is less than 2 g / m ^2, sufficient heat seal strength cannot be satisfied. On the contrary, when it exceeds 10 g / m ² , the quality is excessive in terms of heat seal strength and the plastic reduction effect is poor. In the wrapping paper of the present invention, the heat seal layer is usually not provided only on a part of the surface of the paper base material, but is usually provided on the entire surface. That is, the heat seal layer is provided not only on the portion necessary for adhesion by the heat seal, such as a net shape, an island shape, or a linear shape, but is provided so as to cover the entire surface of the paper base material. Is good.

In addition to the ionomer emulsion, various auxiliaries may be added to the coating liquid for the heat seal layer. For example, viscosity modifiers, antifoaming agents, leveling agents such as surfactants and alcohols, coloring pigments, coloring dyes and the like. However, since the addition of these auxiliaries tends to cause a decrease in heat seal strength, it is preferable to add them in a small amount. In the present embodiment, it is preferable that the coating liquid for the heat seal layer is composed only of the ionomer emulsion.

The method for applying the coating liquid for the heat seal layer is not particularly limited, and a generally used coating device can be used. For example, air knife coater, blade coater, gravure coater, rod blade coater, roll coater, reverse roll coater, bar coater, curtain coater, die slot coater, champlex coater, metering blade type size press coater, short dwell coater, spray Various known coating devices such as a coater, a gate roll coater, and a lip coater can be used.

In the present embodiment, it is preferable that the heat seal layer is formed of two or more layers. By having two or more layers, the air permeability of the wrapping paper can be increased, water repellency and oil repellency can be imparted, and characteristics similar to or close to those of the plastic film laminated paper can be obtained. Because. When the number of heat-sealing layers is two or more, it is preferable that the coating amount of the lowest heat-sealing layer closest to the paper substrate is larger than the total coating amount of the other heat-sealing layers. This is because the air permeability of the wrapping paper can be further improved, and the water repellency and oil repellency are further improved.

In the present embodiment, the air permeability of the wrapping paper preferably exceeds 10,000 seconds. It is more preferably 12000 seconds or more, and further preferably 15000 seconds or more. By setting the air permeability of the wrapping paper to 10,000 seconds or more, the barrier property in the sense of blocking air is further enhanced, and the water repellency and oil repellency are further improved. The method of setting the air permeability of the wrapping paper to 10,000 seconds or more is not particularly limited, but can be achieved by using, for example, a paper base material having a high air permeability. Further, the air permeability of the wrapping paper can be increased by increasing the smoothness of the surface to which the heat seal coating liquid is applied. This is because pinholes and cracks can be further reduced in the heat seal layer formed thereafter. For example, the smoothness of the surface to which the heat seal coating liquid is applied can be increased by providing a pigment coating layer and then performing a calender treatment or the like. In addition, coating two or more heat seal layers also has the effect of increasing the air permeability. In the two-layer coating of the heat seal layer, fine pinholes and cracks existing in the first coating layer (lower layer) are removed from the second coating layer (upper layer) provided on the first layer. It is thought that the air permeability will be increased by covering with. Further, increasing the coating amount of the heat seal layer is also effective in improving the air permeability. In terms of film formation of the heat seal layer, the air permeability is likely to be improved by setting the drying temperature of the coating liquid for the heat seal layer after coating to a temperature equal to or higher than the melting point of the ionomer.

In the present embodiment, it is preferable that the smoothness of the surface to which the heat seal coating liquid of the paper base material is applied is 10 seconds or more. More preferably, it is 20 seconds or more. The higher the smoothness of the paper base material, the more likely it is that the film thickness of the heat-sealing layer provided by coating will be uniform (fine irregularities are unlikely to occur), and as a result, variations in heat-sealing strength can be less likely to occur. A uniform heat seal strength can be imparted on a flat surface. The method for increasing the smoothness of the paper substrate is not particularly limited, and examples thereof include a calender treatment using a known calender device such as a super calender, a gloss calender, a shoe nip calender, and a soft calender. .. Further, paper on which the mirror surface of a Yankee dryer is transferred, such as single-gloss kraft paper, is also suitable as a paper base material having high smoothness. The heat-sealing layer may have pinholes and cracks that are invisible to the naked eye, but to that extent, the heat-sealing property is not adversely affected. Further, a leveling agent for the purpose of preventing pinholes can be added to the heat seal layer coating liquid as long as the effects of the present invention are not impaired.

The paper base material used in the present embodiment is not particularly limited, and a known paper base material containing pulp as a main component can be used. The pulp that is the main component of the paper base material is chemical pulp such as LBKP (broadwood bleached kraft pulp) and NBKP (coniferous bleached kraft pulp), GP (crushed wood pulp), PGW (pressurized crushed wood pulp), and RMP (refiner mechanical). Pulp), TMP (thermomechanical pulp), CTMP (chemithermomechanical pulp), CMP (chemimechanical pulp), mechanical pulp such as CGP (chemigrand pulp), wood pulp such as DIP (deinked pulp), and Kenaf, Bagus , Bamboo, cotton and other non-wood pulp can be used. These can be used alone or in admixture in any proportion. For example, 90 to 100 parts by mass of LBKP (hardwood bleached kraft pulp) can be used as the pulp. In addition, synthetic fibers can be further blended as long as the desired effect of the present invention is not impaired. From the viewpoint of environmental protection, ECF (Elemental Chlorine Free) pulp, TCF (Total Chlorine Free) pulp, used paper pulp, and pulp obtained from planted trees are preferable. Further, for example, an appropriate pulp beating degree is 200 to 700 ml CSF, for example, 450 to 620 ml CSF in Canadian standard freeness (JIS P 8121: 1995 "Pulp freshness test method"). ..

As the paper base material, one 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 substrate 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 dry mass of pulp.

Further, the paper base material may contain various known additives for papermaking in addition to pulp and filler. Examples of papermaking additives include internal paper strength enhancers such as sizing agents and wet paper strength enhancers, bulking agents, yield improvers, drainage improvers, color dyes, color pigments, fluorescent whitening agents, and fluorescence. There are decoloring agents, pitch control agents, etc. Further, a water-soluble polymer such as starch, polyvinyl alcohol, or polyacrylamide may be applied.

The paper-based paper-making method is not particularly limited, and is a long-net paper machine, a long-net multi-layer paper machine, a circular net paper machine, a circular net multi-layer paper machine, a long-net circular net combination multi-layer paper machine, and twin wire paper. It can be manufactured with various paper machines such as machines. Further, in the present invention, the paper base material may be a single-layer paper, a multi-layer paper, or a laminated product having a plurality of layers.

The paper base material may be provided with one or more coating layers other than the heat seal layer, and may be provided with, for example, a pigment coating layer containing a pigment and an adhesive. As the pigment in the pigment coating layer, a known pigment used for the coating layer of general printing coated paper can be used, and for example, calcium carbonate (heavy calcium carbonate, light calcium carbonate, etc.), 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 soil, aluminum hydroxide, hydroxide Examples thereof include inorganic pigments such as magnesium, acrylic, styrene, vinyl chloride, nylon itself, and organic pigments (so-called plastic pigments) obtained by copolymerizing these. 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. Further, as the adhesive, a known adhesive used for the coating layer of general printing coated paper can be used. For example, butadiene-based copolymerized latex, cross-linking agent-modified starch, oxidized starch, enzyme-modified starch, etc. Stars such as esterified starch, etherified starch, cationic starch, amphoteric starch, water-soluble polymers such as gelatin, casein, soybean protein, polyvinyl alcohol, vinyl acetate, ethylene vinyl acetate, polyurethane resin, acrylic resin, Examples thereof include synthetic resins such as polyester resins and polyamide resins. 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 intended effect of the present invention is not impaired. For example, a viscosity modifier, a softener, a gloss imparting agent, a water resistant agent, a dispersant, and a flow modifier. , UV absorbers, stabilizers, antistatic agents, cross-linking agents, sizing agents, optical brighteners, colorants, pH adjusters, antifoaming agents, plasticizers, preservatives may be included. The coating amount of such a pigment coating layer is, for example, ² to 40 g / m ² in terms of solid content per one side of the base paper. As one of the wrapping paper embodiments of the present invention, the heat seal layer may be provided on such a pigment coating layer, and in another embodiment, the pigment coating layer is provided on only one surface. The heat seal layer may be provided on the surface of the paper base material provided with the above on which the pigment coating layer is not provided.

In the present embodiment, the basis weight of the wrapping paper is not particularly limited, but is, for example, 10 to 1000 g / m ² . Barrier properties, comprising highly water and oil repellency, as the basis weight of the wrapping paper can also be used in flexible packaging, preferably ^{30~500g / m 2, 50~300g / m} 2 is more preferable.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Further, "parts" and "%" in the example indicate "parts by mass" and "% by mass", respectively, unless otherwise specified. The number of copies added is a value in terms of solid content.

(Example 1)
(Preparation of base paper)
Canadian Standard Freeness 520ml csf 100 parts of broadleaf bleached kraft pulp, 5 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.), cationized starch (trade name: Neotac 30T, manufactured by Nippon Food Processing Co., Ltd.) 0.2 Part, neutral rosin size (trade name: CC167, manufactured by Seiko PMC) Add water to 0.2 part to prepare the paper material, and use a long net multi-cylinder paper machine to make a base paper with a basis weight of 58 g / m ² . Was produced. Oxidized starch (trade name: MS3800, manufactured by Nihon Shokuhin Kako Co., Ltd.) is applied to this base paper by a gate roll coater so that the dry coating amount per both sides is 2 g / m ^2, and the base is dried and dried to 60 g / m ² . I got the paper.

(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: Carvilax, manufactured by Imerys) and dispersant (trade name: Aron T-50, manufactured by Toa Synthetic) 0.2 part was added, water was added, and water was dispersed using a choles disperser to prepare a pigment slurry. To this pigment slurry, 2 parts of phosphoric acid esterified starch (trade name: MS4600, manufactured by Nippon A & L Inc.), 8 parts of styrene butadiene latex (trade name: PA0372, Nippon A & L Inc.), and water are further added and dispersed as a binder. Then, a coating liquid for a pigment coating layer having a solid content concentration of 50% was prepared.

(Preparation of paper substrate)
On both sides of the base paper obtained above, the coating liquid for the pigment coating layer was applied and dried using a blade coater so that the dry coating amount per one side was 10 g / m ² . Then, a calender treatment was performed to prepare a paper base material (coated paper) having 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.

(Making wrapping paper)
Water-based ionomer emulsion (trade name: Chemipal S-300, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, microtrack method) on one side of the paper substrate obtained above. (Average particle size 0.5 μm) was coated with an air knife coater so that the dry coating amount was 5 g / m ² , dried to provide a heat seal layer, and a wrapping paper was prepared.

(Example 2)
A wrapping 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 .

(Example 3)
A wrapping 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 .

(Example 4)
A wrapping paper was produced in the same manner as in Example 1 except that the coating amount of the heat seal layer was changed to ² g / m ² .

(Example 5)
A wrapping paper was produced in the same manner as in Example 1 except that the coating amount of the heat seal layer was changed to 3 g / m ² .

(Example 6)
A base paper was prepared in the same manner as in Example 1. Next, the same coating liquid for the pigment coating layer as in Example 1 was applied as a lower layer on both sides with a gate roll coater with a dry coating amount of 10 g / m ² per side. Next, the same coating liquid for the coating layer as in Example 1 was applied as an upper layer on both sides with a blade coater with a dry coating amount of 10 g / m ² per side, super calendered, and the basis weight was 100 g. A paper substrate (coated paper) of / m ² was prepared. At this time, the smoothness of the coated surface (the surface on which the heat seal layer is provided in the subsequent process) 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 prepare a wrapping paper.

(Example 7)
(Preparation of paper substrate)
Canadian Standard Freeness 580ml csf 100 parts of broadleaf bleached kraft pulp, 5 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.), cationized starch (trade name: Neotac 30T, manufactured by Nippon Food Processing Co., Ltd.) 0.2 Part, neutral rosin size (size pine NT-78: manufactured by Arakawa Chemical Industry Co., Ltd.) Add water to 0.2 part to prepare the paper material, and use a long net multi-cylinder paper machine to make a basis weight of 188 g / m ^2. The base paper of was prepared. Oxidized starch (trade name: MS3800, manufactured by Nihon Shokuhin Kako Co., Ltd.) is applied to this base paper by a size press so that the dry coating amount per both sides is 2 g / m ^2, and the paper base is dried to 190 g / m ² . I got the wood. At this time, the smoothness of the surface of the paper base material (the surface on which the heat seal layer is provided in the subsequent process) was 10 seconds.

(Making wrapping paper)
Water-based ionomer emulsion (trade name: Chemipal S-100, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, microtrack method) on one side of the paper substrate obtained above. The average particle size (0.1 μm) was coated with an air knife coater so that the dry coating amount was 6 g / m ^2, and the mixture was dried to provide a heat seal layer to prepare a wrapping paper.

(Example 8)
A wrapping paper was produced in the same manner as in Example 7 except that the base paper was subjected to a calender treatment after the oxide starch was applied. At this time, the smoothness of the base paper surface (the surface on which the heat seal layer is provided in the subsequent process) was 20 seconds.

(Example 9)
(Preparation of paper substrate)
Canadian Standard Freeness 580ml csf 100 parts of broadleaf bleached kraft pulp, 5 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.), cationized starch (trade name: Neotac 30T, manufactured by Nippon Food Processing Co., Ltd.) 0.2 Add water to 0.2 parts of neutral rosin size (Size Pine NT-78: manufactured by Arakawa Chemical Industry Co., Ltd.) to prepare a paper material, and use a three-layer long net multi-cylinder paper machine to weigh 298 g / were prepared m ² base paper (3-ply). Oxidized starch (trade name: MS3800, manufactured by Nihon Shokuhin Kako Co., Ltd.) is applied to this base paper by a size press so that the dry coating amount per both sides is 2 g / m ² , dried and soft-calendered to the basis weight. A paper substrate of 300 g / m ² was obtained. The smoothness of the surface of the paper substrate (the surface on which the heat seal layer is provided in the subsequent process) was 100 seconds.

(Making wrapping paper)
Water-based ionomer emulsion (trade name: Chemipal S-500, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, microtrack method) on one side of the paper substrate obtained above. An average particle size of 0.7 μm) was coated with an air knife coater so that the dry coating amount was 4 g / m ² , dried to provide a heat seal layer, and a wrapping paper was prepared.

(Example 10)
On one side of the paper substrate obtained in Example 9, the same coating liquid for the pigment coating layer as in Example 1 was applied with an air knife coater so that the dry coating amount was 20 g / m ^2. Then, a soft calender treatment was performed to prepare a 320 g / m ² paper substrate. The smoothness of the uncoated surface of the paper substrate (the surface of the paper substrate not provided with the pigment coating layer) was 150 seconds. Next, a heat seal layer was provided on the uncoated surface of the paper base material obtained above in the same manner as in Example 1, to prepare a wrapping paper.

(Example 11)
On one side of the paper substrate obtained in Example 9, an aqueous ionomer emulsion (trade name: Chemipal S-300, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, micro The truck method (average particle size of 0.5 μm) was coated with an air knife coater so that the dry coating amount was 5 g / m ^2, and dried to provide a heat seal layer (lower layer). Next, the same aqueous ionomer emulsion is applied to the surface of the heat seal layer (lower layer) using an air knife coater so that the dry coating amount is 2 g / m ^2, and the heat seal layer (upper layer) is dried. It was provided and a wrapping paper was prepared.

(Example 12)
A water-based ionomer emulsion (trade name: MYE-30ER, manufactured by Maruyoshi Chemical Co., Ltd., composition:) was prepared on the non-coated surface of the paper substrate (the surface of the paper substrate not provided with the pigment coating layer) prepared in Example 10. A metal salt of an ethylene / methacrylic acid copolymer, a self-emulsifying emulsion, and a microtrack method with an average particle size of 0.2 μm) are coated with an air knife coater so that the dry coating amount is 3 g / m ² . After drying, a heat seal layer (lower layer) was provided. Next, on the surface of the heat seal layer (lower layer), an aqueous ionomer emulsion (trade name: MYE-30MAZ, manufactured by Maruyoshi Chemical Co., Ltd., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, microtrack method average. A particle size (0.3 μm) was coated with an air knife coater so that the dry coating amount was 1 g / m ^2, and the mixture was dried to provide a heat seal layer (upper layer) to prepare a wrapping paper.

(Example 13)
An aqueous ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Kagaku Co., Ltd.) was prepared on the non-coated surface of the paper substrate (the surface of the paper substrate not provided with the pigment coating layer) prepared in Example 10, composition: A metal salt of an ethylene / methacrylic acid copolymer, a self-emulsifying emulsion, and a microtrack method average particle size of 0.5 μm) are coated using an air knife coater so that the dry coating amount is 5 g / m ^2. After drying, a heat seal layer (lower layer) was provided. Next, the same aqueous ionomer emulsion is applied to the surface of the heat seal layer (lower layer) using an air knife coater so that the dry coating amount is 1 g / m ^2, and the heat seal layer (upper layer) is dried. It was provided and a wrapping paper was prepared.

(Example 14)
An aqueous ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Kagaku Co., Ltd.) was prepared on the non-coated surface of the paper substrate (the surface of the paper substrate not provided with the pigment coating layer) prepared in Example 10, composition: A metal salt of an ethylene / methacrylic acid copolymer, a self-emulsifying emulsion, and a microtrack method average particle size of 0.5 μm) are coated using an air knife coater so that the dry coating amount is 1 g / m ^2. After drying, a heat seal layer (lower layer) was provided. Next, the same aqueous ionomer emulsion is applied to the surface of the heat seal layer (lower layer) using an air knife coater so that the dry coating amount is 9 g / m ^2, and the heat seal layer (upper layer) is dried. It was provided and a wrapping paper was prepared.

(Example 15)
An aqueous ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Kagaku Co., Ltd.) was prepared on the non-coated surface of the paper substrate (the surface of the paper substrate not provided with the pigment coating layer) prepared in Example 10, composition: A metal salt of an ethylene / methacrylic acid copolymer, a self-emulsifying emulsion, and a microtrack method average particle size of 0.5 μm) are coated using an air knife coater so that the dry coating amount is 9 g / m ^2. After drying, a heat seal layer (lower layer) was provided. Next, the same aqueous ionomer emulsion is applied to the surface of the heat seal layer (lower layer) using an air knife coater so that the dry coating amount is 1 g / m ^2, and the heat seal layer (upper layer) is dried. It was provided and a wrapping paper was prepared.

(Example 16)
Water-based ionomer emulsion (trade name: Chemipal S-300, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, microtrack) on one side of the paper substrate prepared in Example 7. The legal average particle size (0.5 μm) was coated with an air knife coater so that the dry coating amount was 5 g / m ^2, and dried to provide a heat seal layer (lower layer). Next, the same aqueous ionomer emulsion is applied to the surface of the heat seal layer (lower layer) using an air knife coater so that the dry coating amount is 1 g / m ^2, and the heat seal layer (upper layer) is dried. It was provided and a wrapping paper was prepared.

(Example 17)
Water-based ionomer emulsion (trade name: Chemipal S-300, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, microtrack) on both sides of the paper substrate prepared in Example 7. The legal average particle size (0.5 μm) was coated with an air knife coater so that the dry coating amount per one side was 5 g / m ^2, and dried to provide a heat seal layer (lower layer). Next, the same aqueous ionomer emulsion is applied to the surface of the heat seal layer (lower layer) on both sides of the upper base material using an air knife coater so that the amount of dry coating per side is 1 g / m ^2, and the mixture is dried. Then, a heat seal layer (upper layer) was provided to prepare a wrapping paper.

(Comparative Example 1)
Low-density polyethylene (Petrosen DLZ19A, manufactured by Tosoh Corporation) is laminated on one side of the paper substrate produced in Example 1 with an extraction coater (melt extruder) so that the coating amount is 30 g / m ^2. A heat seal layer was provided to prepare a wrapping paper.

(Comparative Example 2)
Polypropylene (Novatec FL03H, manufactured by Japan Polypropylene Corporation) is laminated on one side of the paper base material produced in Example 1 with an extraction coater (melt extruder) so that the coating amount is 30 g / m ^2. A heat seal layer was provided to prepare a wrapping paper.

(Comparative Example 3)
A wrapping paper was produced in the same manner as in Example 1 except that the water-based ionomer emulsion was changed to a water-based polyethylene emulsion (manufactured by San Nopco, SN Coat 287).

(Comparative Example 4)
A wrapping paper was produced in the same manner as in Example 1 except that the water-based ionomer emulsion was changed to a water-based polypropylene emulsion (manufactured by Toho Chemical Industry Co., Ltd., Hi-Tech P-5300).

The wrapping papers obtained in each Example and Comparative Example were evaluated by the methods shown below. The results obtained are shown in Tables 1 to 3. When there is only one heat seal layer, the coating amount is described in the coating amount column of the upper layer of the heat seal layer for convenience.

(1) Smoothness In accordance with JIS P 8155: 2010, heat seal of paper base material with a digital type Oken type air permeability smoothness tester (manufactured by Asahi Seiko Co., Ltd., model number: EYDO-6-2M). The smoothness (seconds) of the surface close to the layer (heat seal layer forming surface) before the heat seal layer was provided was measured. The higher the value, the smoother the surface of the paper substrate.

(2) Air permeability In accordance with JIS P 8117: 2009, the air permeability of the wrapping paper is measured by a digital type Oken type air permeability smoothness tester (manufactured by Asahi Seiko Co., Ltd., model number: EYDO-6-2M). Degrees (seconds) were measured. The higher the value, the lower the air permeability (higher barrier property).

(2) Heat-sealing strength Two sheets of the obtained wrapping paper are cut into a size of 8 mm in width and 15 cm in length, and the front and back surfaces of the wrapping paper are overlapped to form a heat-sealing device (manufactured by Palmec, model number: PTS-). Under 100), heat sealing was performed under certain conditions (adhesion width: 4 mm, temperature: 180 ° C., pressure 0.4 MPa, pressing time 0.5 seconds, pitch: 4 mm). Next, the heat-sealed sample was measured for peel strength under certain conditions (peeling speed: 100 mm / min, peeling length: 10 cm) with a peel strength tester (manufactured by Shimadzu Corporation, model number: Autograph AGS-X). The heat seal strength (gf / 4 mm) was used. The higher the number, the better. If both sides are heat-sealed layers, it means the adhesive strength between the heat-sealed layers.

(3) Water repellency The water repellency of the surface of the heat seal layer was evaluated according to JIS K 6768: 1999 (plastic-film and sheet-wetting tension test method). The lower the number, the higher the water repellency (difficult to get wet). When there were heat seal layers on both sides, the average value on both sides was used.

(4) Oil repellency The oil repellency of the surface of the heat seal layer was evaluated according to TAPPI T-559 cm-02 (kit method). The higher the value (kit value), the higher the oil repellency. When there were heat seal layers on both sides, the average value on both sides was used.

As is clear from Tables 1 to 3, the wrapping paper according to Examples 1 to 17 has the same or higher heat seal strength as compared with Comparative Examples 1 and 2, although the amount of the heat seal layer is significantly reduced. It was. Further, as compared with Comparative Examples 3 and 4, the heat seal strength was clearly excellent. As the experimental results show, according to the present invention, the amount of the heat seal layer used is significantly reduced as compared with the conventional amount of polyethylene laminate, which contributes to the reduction of plastic dust, and has barrier properties, water repellency and water repellency. It is possible to provide a wrapping paper having excellent oiliness.

Claims (7)

A wrapping paper having at least one heat-sealing layer on at least one surface of a paper substrate, wherein the heat-sealing layer contains an ionomer, and the dry coating amount of the heat-sealing layer is 2 to 10 g / g in all layers. A wrapping paper characterized by being m ² . The wrapping paper according to claim 1, wherein two or more heat-sealing layers are formed on at least one surface. The wrapping paper according to claim 1 or 2, wherein the air permeability exceeds 10,000 seconds. The wrapping paper according to any one of claims 1 to 3, wherein the ionomer is a metal salt of an ethylene / methacrylic acid copolymer. The process of preparing a coating liquid for a heat seal layer containing an ionomer emulsion, and
A method for producing a wrapping paper, which comprises a step of applying the coating liquid for a heat seal layer on at least one surface of a paper base material in a range of ² to 10 g / m ^{2 in} terms of solid content. The method for producing a wrapping paper according to claim 5, wherein the coating liquid for the heat seal layer is applied to a surface of the paper substrate having a smoothness of 10 seconds or more. The method for producing a wrapping paper according to claim 5 or 6, wherein the ionomer emulsion is a self-emulsifying emulsion.