JP6580291B1 - Wrapping paper - Google Patents

Abstract

An object of this invention is to provide the packaging paper which reduced the usage-amount of the plastic. The present invention is a wrapping paper having at least one heat seal layer on at least one surface of a paper substrate, wherein the heat seal layer contains an ionomer, and the dry coating amount of the heat seal layer is a total layer. It is related with the packaging paper characterized by being 2-10 g / m2.

Description

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

  In recent years, the plastic garbage problem has become serious. The world's plastic production is said to exceed 400 million tons / year. Among them, plastic production in the packaging container sector is large, causing plastic waste. Plastic does not break down semipermanently, and the waste is microplasticized in the natural environment, which has a serious adverse effect on the ecosystem. As plastics used for packaging containers, polyethylene terephthalate (PET) used for beverage bottles, plastic bags, polyethylene (PE) and polypropylene (PP) used for container lamination are most frequently used. . In particular, the ocean is extremely polluted and the plastic waste is said to be uncollectable. In the future, it will be necessary for the global environment to reduce the use of plastics.

  On the other hand, the application of biodegradable plastics that can be completely decomposed by microorganisms has been proposed all over the world as a measure against plastic waste. Biodegradable plastics are naturally decomposed within a certain period of time, but they are still garbage until they are decomposed, and unless they are used and discarded, they cannot be said to be effective measures immediately ( (See Patent Documents 1 and 2).

As an immediate countermeasure, it has been proposed to replace plastic with paper. However, when processing paper into bags and containers, a large amount of polyethylene or polypropylene is used as a heat sealant. The 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 means for directly reducing the use of plastic.

JP 2012-148444 A JP 2013-141663 A

  The objective of this invention is providing the packaging paper which can reduce the usage-amount of a plastic.

In the present invention, an ionomer is used in order to reduce the amount of polyethylene or polypropylene used in conventional plastic laminated paper (hereinafter sometimes abbreviated as polylaminated paper). That is, the wrapping paper according to the present invention is a wrapping paper having at least one heat seal layer on at least one surface of a paper substrate, wherein the heat seal layer contains an ionomer, and the coating amount of the heat seal layer is ² to 10 g / m ² . Compared to the amount of polyethylene or polypropylene laminated used in the heat seal layer of conventional polylaminated paper exceeds 20 g / m ² , the amount of plastic used for the heat seal layer is about 10 to 50% of the conventional amount. Can be reduced. Here, the ionomer is a synthetic resin in which a polymer is aggregated using 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, an acrylic polymer and ethylene are produced by intermolecular bonding 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 and oil repellency.

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

  In the present invention, the ionomer may be a metal salt of an ethylene / methacrylic acid copolymer. Wrapping paper having better heat sealability can be obtained.

Further, the method for producing a wrapping paper in the present invention comprises a step of preparing a heat seal layer coating solution containing an ionomer emulsion, and the heat seal layer coating solution is solidified on at least one surface of the paper substrate. And a step of coating in the range of ² to 10 g / m ^{2 in} terms of minutes. In particular, by using an aqueous ionomer emulsion as the ionomer emulsion, the coating amount can be controlled to be relatively low, and since there is no VOC emission, a packaging paper with a small environmental load can be obtained.

  Moreover, in this invention, it is preferable to apply | coat the said coating liquid for heat seal layers to the surface where the smoothness of the said paper base material is 10 second or more. The heat seal layer is preferable because it is easy to form a uniform thin film layer without being island-like or net-like, and there is less variation in heat seal strength, resulting in higher heat seal strength of the wrapping paper. The heat seal strength is a characteristic that is most strongly required when a packaging container is processed using packaging paper.

  In the present invention, the ionomer emulsion may be a self-emulsifying emulsion. Even if it is a thin film, the packaging paper which has a heat seal layer with a uniform film thickness can be obtained.

  According to the present invention, it is possible to manufacture a wrapping paper in which the amount of plastic used is reduced. If it is a container product using the packaging paper of the present invention, it is possible to reduce the adverse effects of plastic waste on the natural environment even if it is inappropriately released as waste in nature. Helps solve the garbage problem. The packaging paper in the present invention is processed into general packaging containers such as bags, food cups such as ice cream, beverage cups such as coffee, food containers such as hot snacks, and trays, boxes, cases, containers, envelopes, etc. Is possible.

  Next, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

  In the present embodiment, the ionomer is a general term for synthetic resins in which a polymer is used as an aggregate using 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, metal salt of ethylene / methacrylic acid copolymer, metal salt of ethylene / acrylic copolymer, metal salt of ethylene / urethane copolymer, metal salt of 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, the ionomer is preferably 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 at least coating amount of the heat seal layer.

In the present embodiment, a heat seal layer can be provided by applying a coating solution for heat seal layer containing an ionomer emulsion to at least one surface of a paper substrate and drying. By using an ionomer emulsion, the coating amount can be controlled to be relatively low, and by using an aqueous ionomer emulsion, VOC emission is 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 , preferably 3 to 8 g / m ² in terms of solid content per one side of the paper substrate. When it is less than 2 g / m ^2, sufficient heat seal strength cannot be satisfied. On the other hand, if it exceeds 10 g / m ² , the quality is excessive from the viewpoint of heat seal strength, and the effect of reducing plastics is poor. In the wrapping paper of the present invention, the heat seal 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 seal layer is provided not only on the part necessary for adhesion by heat seal, such as a net, island, or line, but to cover the entire surface of the paper substrate. And good.

  In addition to the ionomer emulsion, various auxiliary agents may be added to the heat seal layer coating solution. For example, viscosity modifiers, antifoaming agents, leveling agents such as surfactants and alcohols, colored pigments, colored dyes and the like. However, since the addition of these auxiliaries tends to cause a decrease in heat seal strength, a small amount is preferable when added. In this embodiment, it is preferable that the heat-seal layer coating solution is composed only of an ionomer emulsion.

  The method for coating the heat-seal layer coating solution is not particularly limited, and a commonly used coating apparatus 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 apparatuses 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 using 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 similar to those of plastic film laminated paper can be obtained. Because. When there are two or more heat seal layers, it is preferable that the coating amount of the lowermost heat seal layer closest to the paper substrate is larger than the total coating amount of the other heat seal 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, it is preferable that the air permeability of the wrapping paper exceeds 10,000 seconds. More preferably, it is 12000 seconds or more, More preferably, it is 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 for setting the air permeability of the wrapping paper to 10,000 seconds or more is not particularly limited, but for example, it can be achieved by using a paper substrate having a high air permeability. Furthermore, the air permeability of the wrapping paper can also be increased by increasing the smoothness of the surface on 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 on which the heat seal coating solution is applied can be increased by providing a pigment coating layer and then performing a calendar process or the like. In addition, coating two or more heat seal layers also has an effect of increasing the air permeability. The two-layer coating of the heat seal layer is a second coating layer (upper layer) provided on the first layer with fine pinholes and cracks present in the first coating layer (lower layer). It is thought that the air permeability increases by covering. Further, increasing the coating amount of the heat seal layer is also effective for improving the air permeability. In terms of film formation of the heat seal layer, the air permeability is easily improved by setting the drying temperature after coating of the coating solution for the heat seal layer 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 of the paper base on which the heat seal coating solution 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 easier it is to make the film thickness of the heat seal layer applied and uniform (fine irregularities are less likely to occur), resulting in less variation in heat seal strength, 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 calendar processing by a known calendar device such as a super calendar, gloss calendar, shoe nip calendar, and soft calendar. . Also, paper with a mirror surface of a Yankee dryer such as single gloss kraft paper is suitable as a paper substrate with high smoothness. Note that pinholes and cracks that are invisible to the naked eye may be present in the heat seal layer, but if this is the case, the heat sealability is not adversely affected. Moreover, unless the effect of this invention is impaired, the leveling agent aiming at pinhole prevention can also be added in a heat seal layer coating liquid.

  It does not specifically limit as a paper base material used in this embodiment, The well-known paper base material which has a pulp as a main component can be used. Pulp that is the main component of the paper base includes chemical pulps such as LBKP (hardwood bleached kraft pulp), NBKP (softwood bleached kraft pulp), GP (crushed wood pulp), PGW (pressurized groundwood pulp), RMP (refiner mechanical) Pulp), TMP (thermomechanical pulp), CTMP (chemithermomechanical pulp), mechanical pulp such as CMP (chemimechanical pulp), CGP (chemiground pulp), wood pulp such as DIP (deinked pulp) and kenaf, bagasse Non-wood pulp such as bamboo and cotton can be used. These can be used alone or in admixture at any ratio. For example, 90 to 100 parts by mass of LBKP (hardwood bleached kraft pulp) can be used as the pulp. In addition, a synthetic fiber can be further blended within a range that does not impair the intended effect of the present invention. From the viewpoint of environmental conservation, ECF (Elemental Chlorine Free) pulp, TCF (Total Chlorine Free) pulp, waste paper pulp, and pulp obtained from planted trees are preferable. In addition, for example, an appropriate pulp beating degree is 200 to 700 ml CSF, for example, 450 to 620 ml CSF, according to Canadian standard freeness (JIS P 8121: 1995 “Pulp Freeness Test Method”). .

  As the paper substrate, 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 good to contain 1-10 mass parts of light calcium carbonate with respect to 100 mass parts of dry mass of a pulp.

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

  The paper making method of the paper base is not particularly limited, and is a long web paper machine, a long web multi-layer paper machine, a circular net paper machine, a circular net multi-layer paper machine, a long net-mesh combination multi-layer paper machine, and a twin wire paper machine. It can be manufactured by various paper machines such as a machine. In the present invention, the paper substrate may be a single layer paper, a multilayer paper, or a multi-layer bonded product.

The paper base material may be provided with one or more coating layers other than the heat seal layer. For example, the paper base material may be provided with a pigment coating layer containing a pigment and an adhesive. As the pigment in the pigment coating layer, a known pigment used in a coating layer of a general printing coated paper can be used. 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 earth, aluminum hydroxide, hydroxide Examples thereof include inorganic pigments such as magnesium, or acrylic, styrene, vinyl chloride, nylon itself, and organic pigments (so-called plastic pigments) obtained by copolymerizing these. For example, as a pigment, the combination of 20-40 mass parts kaolin and 60-80 mass parts heavy calcium carbonate can be used. Moreover, the well-known adhesive used for the coating layer of general printing coated paper can also be used for an adhesive agent, for example, a butadiene type copolymer latex, a crosslinking agent modified starch, an oxidized starch, an enzyme modified starch, Starch such as esterified starch, etherified starch, cationic starch, amphoteric starch, water-soluble polymers such as gelatin, casein, soy 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 is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the pigment. For example, as an 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 within a range that does not impair the intended effect of the present invention, such as a viscosity modifier, a softening agent, a gloss-imparting agent, a water-resistant agent, a dispersant, and a flow modifier. UV absorbers, stabilizers, antistatic agents, crosslinking agents, sizing agents, fluorescent brighteners, colorants, pH adjusters, antifoaming agents, plasticizers, preservatives may be contained. Moreover, as a coating amount of such a pigment coating layer, it is 2-40 g / m < ² > in conversion of solid content per single side | surface of a base paper, for example. As one embodiment of the wrapping paper of the present invention, the heat seal layer may be provided on such a pigment coating layer. In another embodiment, the pigment coating layer is provided only on one side. A heat seal layer may be provided on the surface of the paper substrate provided with the surface where 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 more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, “parts” and “%” represent “parts by mass” and “mass%”, respectively, unless otherwise specified. The number of added parts is a value in terms of solid content.

Example 1
(Preparation of base paper)
Canadian standard freeness 520mlcsf hardwood bleached kraft pulp 100 parts, light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) 5 parts, 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 Co., Ltd.) 0.2 part, water is added to prepare a stock, and a base paper having a basis weight of 58 g / m ² using a long-mesh multi-cylinder paper machine. Was made. This base paper was coated with oxidized starch (trade name: MS3800, manufactured by Nippon Food Chemicals Co., Ltd.) using a gate roll coater so that the dry coating amount per side was 2 g / m ^2, and dried to give a base of 60 g / m ² . I got paper.

(Preparation of coating solution for pigment coating layer)
Dispersant (trade name: Aron T-50, manufactured by Toa Gosei Co., Ltd.) in 30 parts of kaolin (trade name: Contour 1500, manufactured by Imeris) and 70 parts of heavy calcium carbonate (trade name: Carvilax, manufactured by Imeris) Add 0.2 part, add water, and disperse in water using a coreless disperser to prepare a pigment slurry. To this pigment slurry, 2 parts of phosphate esterified starch (trade name: MS4600, manufactured by Nippon Food Processing Co., Ltd.) and 8 parts of styrene butadiene latex (trade name: PA0372, Nippon A & L Co., Ltd.) as a binder are added and dispersed by adding water. Thus, a coating liquid for a pigment coating layer having a solid content concentration of 50% was prepared.

(Preparation of paper substrate)
The pigment coating layer coating solution was applied on both sides of the base paper obtained above using a blade coater so that the dry coating amount per side was 10 g / m ² and dried. Then, the calendar process was performed and the paper base material (coated paper) whose basic weight is 80 g / m < ² > was produced. The smoothness of the coated surface at this time (the surface on which the heat seal layer was provided in the subsequent step) was 400 seconds.

(Production of packaging paper)
A water-based ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Chemicals, Ltd., 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 0.5 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 seal layer to prepare a packaging paper.

(Example 2)
In Example 1, a 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 .

(Example 3)
In Example 1, a 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 .

Example 4
In Example 1, a 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 ² g / m ² .

(Example 5)
In Example 1, 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. Subsequently, the same coating liquid for a pigment coating layer as that of Example 1 was applied as a lower layer by a gate roll coater on both sides with a dry coating amount of 10 g / m ² per side. Next, the same coating layer coating solution as in Example 1 was applied as a top layer with a blade coater on both sides with a dry coating amount of 10 g / m ² per side, super calender treated, and a basis weight of 100 g. A paper substrate (coated paper) of / m ² was produced. The smoothness of the coated surface at this time (the surface on which the heat seal layer was provided in the subsequent step) was 2500 seconds. Next, a heat seal layer was provided on one side of the paper substrate obtained above in the same manner as in Example 1 to produce a packaging paper.

(Example 7)
(Preparation of paper substrate)
Canadian standard freeness 580mlcsf hardwood bleached kraft pulp 100 parts, light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) 5 parts, 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 Co., Ltd.) 0.2 part, water is added to prepare a paper stock, and basis weight is 188 g / m ² using a long mesh multi-cylinder paper machine. A base paper was prepared. This base paper was coated with oxidized starch (trade name: MS3800, manufactured by Nippon Shokuhin Kako Co., Ltd.) by a size press so that the dry coating amount per side was 2 g / m ^2, and dried to a paper base of 190 g / m ² . The material was obtained. At this time, the smoothness of the surface of the paper substrate (the surface on which the heat seal layer was provided in the subsequent step) was 10 seconds.

(Production of packaging paper)
A water-based ionomer emulsion (trade name: Chemipearl 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. An average particle diameter of 0.1 μm) was applied using an air knife coater so that the dry coating amount was 6 g / m ² , and dried to provide a heat seal layer to prepare a packaging paper.

(Example 8)
A wrapping paper was prepared in the same manner as in Example 7 except that the base paper was calendered after the oxidized starch was applied. At this time, the smoothness of the surface of the base paper (the surface on which the heat seal layer was provided in the subsequent step) was 20 seconds.

Example 9
(Preparation of paper substrate)
Canadian standard freeness 580mlcsf hardwood bleached kraft pulp 100 parts, light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) 5 parts, 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 Co., Ltd.) 0.2 part, water is added to prepare a stock, and a basis weight of 298 g / using a three-layer long net multi-cylinder paper machine. An m ² base paper (three-layer paper making) was prepared. This base paper was coated with oxidized starch (trade name: MS3800, manufactured by Nippon Shokuhin Kako Co., Ltd.) using a size press so that the dry coating amount per side was 2 g / m ² , dried and soft-calendered, and the basis weight was applied. 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 step) was 100 seconds.

(Production of packaging paper)
A water-based ionomer emulsion (trade name: Chemipearl 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 diameter of 0.7 μm) was applied using an air knife coater so as to have a dry coating amount of 4 g / m ² , and dried to provide a heat seal layer to prepare a packaging paper.

(Example 10)
On one side of the paper substrate obtained in Example 9, the same pigment coating layer coating solution 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 process was performed to produce a 320 g / m ² paper substrate. The smoothness of the non-coated surface of the paper substrate (the surface on which the pigment coated layer of the paper substrate was not provided) 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 to produce a packaging paper.

(Example 11)
An aqueous ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, micro A track method average particle diameter of 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 seal layer (lower layer). Next, the water-based 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 dried to form the heat seal layer (upper layer). A wrapping paper was prepared.

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

(Example 13)
A water-based ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Chemicals, Inc., composition) on the non-coated surface of the paper substrate prepared in Example 10 (the surface on which the pigment coating layer of the paper substrate is not provided). Apply a metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, Microtrac method average particle size 0.5μm) using an air knife coater so that the dry coating amount is 5 g / m ^2. And dried to provide a heat seal layer (lower layer). Next, the water-based 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 dried to form the heat seal layer (upper layer). A wrapping paper was prepared.

(Example 14)
A water-based ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Chemicals, Inc., composition) on the non-coated surface of the paper substrate prepared in Example 10 (the surface on which the pigment coating layer of the paper substrate is not provided). Apply a metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, Microtrac method average particle size 0.5μm) using an air knife coater so that the dry coating amount is 1 g / m ^2. And dried to provide a heat seal layer (lower layer). Next, the water-based 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 dried to form the heat seal layer (upper layer). A wrapping paper was prepared.

(Example 15)
A water-based ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Chemicals, Inc., composition) on the non-coated surface of the paper substrate prepared in Example 10 (the surface on which the pigment coating layer of the paper substrate is not provided). Use an air knife coater to apply a metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, Microtrac method average particle size 0.5 μm) so that the dry coating amount is 9 g / m ^2. And dried to provide a heat seal layer (lower layer). Next, the water-based 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 dried to form the heat seal layer (upper layer). A wrapping paper was prepared.

(Example 16)
A water-based ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, Microtrac is provided on one side of the paper substrate produced in Example 7. (Method average particle size 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 seal layer (lower layer). Next, the water-based 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 dried to form the heat seal layer (upper layer). A wrapping paper was prepared.

(Example 17)
A water-based ionomer emulsion (trade name: Chemipearl S-300, manufactured by Mitsui Chemicals, Inc., composition: metal salt of ethylene / methacrylic acid copolymer, self-emulsifying emulsion, Microtrac on both sides of the paper substrate prepared in Example 7 The average particle diameter of 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 water-based ionomer emulsion is applied to the surface of the heat seal layer (lower layer) on both surfaces of the upper substrate using an air knife coater so that the dry coating amount per side is 1 g / m ² and dried. Then, a heat seal layer (upper layer) was provided to prepare a packaging paper.

(Comparative Example 1)
On one side of the paper base material produced in Example 1, low density polyethylene (manufactured by Tosoh Corp., Petrocene DLZ19A) is laminated with an extrusion coater (melt extruder) so that the coating amount is 30 g / m ^2. Then, a heat seal layer was provided to prepare a packaging paper.

(Comparative Example 2)
Polypropylene (Nippon Polypro, Novatec FL03H) was laminated on one side of the paper substrate produced in Example 1 with an extrusion coater (melt extruder) so that the coating amount was 30 g / m ^2. A heat seal layer was provided to produce a packaging paper.

(Comparative Example 3)
A 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 (San Nopco, SN Coat 287).

(Comparative Example 4)
A packaging paper was prepared in the same manner as in Example 1 except that the aqueous ionomer emulsion was changed to an aqueous polypropylene emulsion (Hitech P-5300, manufactured by Toho Chemical Industry Co., Ltd.).

  The packaging paper obtained in each example and comparative example was evaluated by the following method. The obtained results are shown in Tables 1-3. In addition, when there was only one heat seal layer, the coating amount was described in the coating amount column of the upper layer of the heat sealing layer for convenience.

(1) Smoothness In accordance with JIS P 8155: 2010, heat seal of paper base material with digital type Oken type air permeability smoothness tester (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 providing the heat seal layer was measured. A higher numerical value indicates that the surface of the paper substrate is smoother.

(2) Air permeability In accordance with JIS P 8117: 2009, the air permeability of the packaging paper was measured with a digital type Oken air permeability smoothness tester (manufactured by Asahi Seiko Co., Ltd., model number: EYDO-6-2M). The degree (second) was measured. Higher values indicate lower air permeability (higher barrier properties).

(2) Heat seal strength The obtained wrapping paper was cut into two pieces having a width of 8 mm and a length of 15 cm, and the front and back surfaces of the wrapping paper were overlapped to form a heat seal device (manufactured by Palmec, 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). Next, the peel strength of the heat-sealed sample was measured under a certain condition (peel rate: 100 mm / min, peel length: 10 cm) with a peel strength tester (manufactured by Shimadzu Corporation, model number: Autograph AGS-X). Heat seal strength (gf / 4mm). Higher numbers are better. In addition, when both surfaces are heat seal layers, it means the adhesive strength between the heat seal layers.

(3) Water Repellency The water repellency of the heat seal layer surface 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 (less wet). In addition, when there existed the heat seal layer on both surfaces, the average value of both surfaces was used.

(4) Oil repellency Based on TAPPI T-559cm-02 (kit method), the oil repellency of the heat seal layer surface was evaluated. A higher value (kit value) indicates higher oil repellency. In addition, when there existed the heat seal layer on both surfaces, the average value of both surfaces was used.

  As is clear from Tables 1 to 3, the wrapping papers according to Examples 1 to 17 had a heat seal strength equal to or higher than that of Comparative Examples 1 and 2 although the amount of heat seal layer was significantly reduced. It was. Moreover, compared with Comparative Examples 3-4, it was excellent in heat-seal strength clearly. As the experimental results show, the present invention significantly reduces the amount of heat seal layer used compared to the amount of conventional polyethylene laminate, contributing to the reduction of plastic waste, while maintaining barrier properties, water repellency and water repellency. It is possible to provide a wrapping paper excellent in oiliness.

Claims (6)

A wrapping paper having at least one heat seal layer on at least one surface of a paper substrate, wherein the heat seal layer contains an ionomer, and the dry coating amount of the heat seal layer is 2 to 10 g / m ² der is, the packaging material, wherein the heat seal layer is characterized in that it is formed two or more layers on at least one surface. The packaging paper according to claim 1 , wherein the air permeability exceeds 10,000 seconds. The packaging paper according to claim 1 or 2 , wherein the ionomer is a metal salt of an ethylene / methacrylic acid copolymer. A step of preparing a heat seal layer coating liquid containing an ionomer emulsion;
On at least one surface of the paper substrate, and a step of coating in the range of 2 to 10 g / m ² in terms of solid content of the heat-seal layer coating solution, any one of claims 1 to 3 A method for producing the wrapping paper described in 1 . The method for producing a wrapping paper according to claim 4 , wherein the heat-seal layer coating solution is applied to a surface of the paper substrate having a smoothness of 10 seconds or more. 6. The method for producing a packaging paper according to claim 4, wherein the ionomer emulsion is a self-emulsifying emulsion.