JP2022043123A - Aqueous heat seal agent, paper substrate for paper container, paper container, and method of producing paper container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous heat seal agent capable of simultaneously exerting both a heat seal function required as an alternative to a polyethylene film used for a paper container such as a paper cup, and waterproof property and strength required to a coating agent for a cup inner surface, and capable of recycling without paper classification, and a paper container using the aqueous heat seal agent.

SOLUTION: The aqueous heat seal agent of the present invention includes an aqueous solvent, an olefin-α,β-unsaturated carboxylic acid copolymer and a wax, where the content of α,β-unsaturated carboxylic acid in the olefin-α,β-unsaturated carboxylic acid copolymer is 8-24 mass%, and the wax is one or more kind(s) of selected from the group consisting of a fatty acid amide wax, a carnauba wax, and a Fisher-Tropsch wax.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a water-based sheet sealant used for a paper container, a paper container paper base material using the water-based heat sealant, a paper container, and a method for manufacturing a paper container.

Paper containers for food, which were developed as ice cream containers in the olden days, have since become popular with vending machines, increasing convenience stores and fast food stores, popularizing outdoor leisure activities, and introducing tea dispensers at work. With social phenomena and changes in the living environment, various beverage paper cups have been improved and their demand has increased dramatically.
In Japan, the advantages of paper containers have been reviewed since the 1970s as a measure against pollution caused by plastic disposal, and paper cups for tea and coffee have since been targeted for desserts such as yogurt, pudding and jelly, and natto and delicatessen. The use is expanding.
Furthermore, in recent years, with the issue of marine plastic waste such as microplastics being highlighted again, renewable resources are one of the materials with functions such as "reusable" and "biodegradable". There is increasing interest in "paper" made from "wood".

Paper cups, which are one of the widely used paper containers for foods, are made of paper, but polyethylene film that reduces recycling efficiency is used as a part of the raw material. A normal paper cup is obtained by bonding a polyethylene film, a polypropylene film, or the like obtained by extruding a polyethylene resin, a polypropylene resin, or the like melted by heat into a film shape to a paper base material. When the polyethylene film is molded into a paper cup, it acts as an adhesive by heat melting under indirect heating such as a burner or hot air, and since the polyethylene film exists inside the paper cup, it is waterproof without the paper base material coming into direct contact with the contents. Gender and strength are given.
However, the laminated polyethylene film does not dissolve in the alkaline solution used in the paper recycling process during paper recycling, so it must be physically removed, which leads to a decrease in recycling efficiency. In addition, marine pollution caused by the outflow of plastic waste into the ocean has become a global problem. The target of the Sustainable Development Goals (SDGs) is "By 2025, prevent and significantly reduce all types of marine pollution, including marine debris and eutrophication, especially pollution from land activities." It has become an important global theme, as it has been raised and it has been agreed to strengthen efforts at the summit (summit of major countries). Therefore, there is a demand for a polyethylene film substitute that can be applied to these applications and does not reduce the paper recycling efficiency. Further, there is a demand for a paper container that does not use a plastic film.

A water-based heat sealant is known as an adhesive that acts as an adhesive when molding a paper cup. For example, in Patent Document 1, an ethylene-based resin aqueous dispersion in which an olefin-α, β-unsaturated carboxylic acid copolymer neutralized with ammonia or an amine and an olefin-based thermoplastic resin other than the above are mixed and dispersed in a specific ratio. It is disclosed that the liquid can be applied as a heat sealant.
Further, in Patent Document 2, an aqueous dispersion containing a polyolefin resin composed of an unsaturated carboxylic acid unit, an ethylene-based hydrocarbon, and an acrylic acid ester or a methacrylic acid ester, a natural wax, and an aqueous medium in a specific ratio. Is disclosed that it can be applied as a heat sealant.
However, these documents only disclose the performance as a so-called heat sealant such as heat seal strength and blocking resistance, and the desired heat seal function and cup inner surface coating as an alternative to the polyethylene film used for paper cups are disclosed. There is no description about the compatibility of waterproofness and strength desired for the agent, and recyclability.

Japanese Unexamined Patent Publication No. 2000-7860 Japanese Unexamined Patent Publication No. 2006-45313

The problems to be solved by the present invention are both a heat sealing function desired as a substitute for a polyethylene film used for a paper container such as a paper cup, a waterproofness and strength desired for a cup inner surface coating agent, and paper recycling. It is an object of the present invention to provide a water-based heat-sealing agent that can be recycled without sorting at times, and a paper container using the water-based heat-sealing agent.

That is, the present invention contains an aqueous solvent, an olefin-α, β-unsaturated carboxylic acid copolymer and a wax, and contains α, β-unsaturated carboxylic acid in the olefin-α, β-unsaturated carboxylic acid copolymer. Provided is an aqueous heat sealant having a content of 8 to 24% by mass and in which the wax is one or more selected from fatty acid amide wax, carnauba wax and Fisher Tropsch wax .

The present invention also provides a paper container paper substrate having the aqueous heat sealant according to claim 1 or 2 on at least one side of the paper substrate.

The present invention also provides a paper container using the paper container having the water-based heat sealant according to claim 1 or 2 on at least one side of the paper base material.

Further, the present invention is made of a paper base material having a resin layer provided at least on the inner surface of the container and the bonding surface when assembling the container, and a cylinder in which the bonding surfaces of the rolled and overlapped ends of the paper substrate are heat-welded. Shaped body member (1) and
Paper having at least a paper base material having a resin layer provided on the inner surface of the container and the bonding surface when assembling the container, and having a plate-shaped bottom member (2) heat-welded to the lower end of the body member (1). It ’s a container manufacturing method.
The resin layer provides a method for producing a paper container made of the dry coating film of the aqueous heat sealant described above.

The water-based heat-sealing agent of the present invention can achieve both the desired heat-sealing function as a substitute for the polyethylene film used for paper containers such as paper cups and the waterproofness and strength required for the inner surface coating agent of the cup, and can be recycled. Sometimes it can be recycled without sorting. Therefore, the aqueous heat sealant of the present invention is useful as a substitute for the polyethylene film in a paper container such as a paper cup.

The aqueous heat sealant of the present invention is characterized by containing an aqueous solvent, an olefin-α, β unsaturated carboxylic acid copolymer and a wax.

(Aqueous solvent)
As the aqueous solvent used in the present invention, water, a water-soluble organic solvent soluble in water, or the like can be used. As the water, pure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, distilled water, or ultrapure water can be used. Further, as the water, using water sterilized by irradiation with ultraviolet rays or addition of hydrogen peroxide prevents the growth of mold or bacteria when the aqueous pigment dispersion or the ink using the aqueous pigment dispersion is stored for a long period of time. It is suitable because it can be used.
Examples of the water-soluble organic solvent include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol and polypropylene glycol; diols such as butanediol, pentandiol and hexanediol; propylene laurate. Glycol esters such as glycols; diethylene glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl, carbitol; glycol ethers such as cellosolves containing propylene glycol ethers, dipropylene glycol ethers, and triethylene glycol ethers; methanol , Ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol and other alcohols; sulfolanes, esters, ketones, γ-butyrolactone and other lactones, N- (2) -Hydroxyethyl) Lactates such as pyrrolidone, various other solvents known as aqueous organic solvents such as glycerin and its polyalkylene oxide adducts and the like can be mentioned. These aqueous organic solvents can be used alone or in combination of two or more. Of these, water is the most preferable.

(Olefin-α, β unsaturated carboxylic acid copolymer)
The olefin-α, β-unsaturated carboxylic acid copolymer used in the present invention includes olefins, α, β-unsaturated carboxylic acids, metal salts of α, β-unsaturated carboxylic acids, and α, β-. Examples thereof include a polymer with at least one monomer selected from the group consisting of unsaturated carboxylic acid esters. Specifically, it is a metal salt of α, β-unsaturated carboxylic acid, α, β-unsaturated carboxylic acid or a copolymer of α, β-unsaturated carboxylic acid ester and olefin, and is olefin-α, β. Unsaturated carboxylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-acrylic acid-maleic anhydride copolymer, ethylene-acrylic acid Examples thereof include an ester-maleic anhydride copolymer, an ethylene-methacrylic acid-maleic anhydride copolymer, an ethylene-methacrylic acid ester-maleic anhydride copolymer, and a metal salt thereof. These copolymers may be used alone or as a mixture of two or more kinds.
Of these, olefin-α and β unsaturated carboxylic acid copolymers are preferable. Examples of the olefin-α, β-unsaturated carboxylic acid copolymer include a random copolymer or a block copolymer of ethylene- and α, β-unsaturated carboxylic acid.

Examples of the olefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, butadiene, dicyclopentadiene and 5-ethylidene-2-. Norbornene and the like can be mentioned. Of these, ethylene is preferable.

Examples of the α, β-unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and the like. Among these, acrylic acid and methacrylic acid are preferably used. These α, β-unsaturated carboxylic acids may be used alone or in combination of two or more.

As the α, β-unsaturated carboxylic acid ester, known acrylic acid or methacrylic acid alkyl esters, hydroxyalkyl esters, alkoxyalkyl esters and the like can be used without particular limitation. For example, specifically, methyl acrylate, ethyl acrylate, isopropyl acrylate, npropyl acrylate, n butyl acrylate, isobutyl acrylate, -2-ethylhexyl acrylate, isooctyl acrylate, n octyl acrylate, acrylate- Acrylic acid esters such as 2-hydroxyethyl and -2-methoxyethyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, npropyl methacrylate, nbutyl methacrylate, isobutyl methacrylate, nhexyl methacrylate, Examples of methacrylic acid esters such as -2-ethylhexyl methacrylate, n-lauryl methacrylate, -2-hydroxyethyl methacrylate, and -2-ethoxyethyl methacrylate can be exemplified. These can be used alone or in combination of two or more.

As a method for producing the olefin-α, β unsaturated carboxylic acid copolymer, it can be obtained by a known method, for example, radical copolymerization under high temperature and high pressure.

The content of the α, β-unsaturated carboxylic acid in the olefin-α, β-unsaturated carboxylic acid copolymer is preferably 8 to 24% by weight, preferably 18 to 23% by weight. When the content of α, β-unsaturated carboxylic acid is less than 8% by weight, dispersibility in an aqueous dispersion medium is poor due to the non-polar property derived from ethylene-unit, and excellent olefin-α, β unsaturated It may be difficult to obtain an aqueous dispersion of a carboxylic acid copolymer resin. Further, when the content of α, β-unsaturated carboxylic acid exceeds 24% by weight, the blocking resistance of the obtained film may deteriorate.

The olefin-α, β unsaturated carboxylic acid copolymer used in the present invention is used as an aqueous dispersion dispersed in an aqueous solvent. The method of dispersing in an aqueous solvent is not particularly limited, and a known method may be used. For example, a method of emulsifying with a surfactant and dispersing in an aqueous solvent, a method of neutralizing an olefin-α, β unsaturated carboxylic acid copolymer with a basic compound and then dispersing in an aqueous solvent can be mentioned.

As the surfactant used for emulsification, various known anionic, cationic, nonionic surfactants, or various water-soluble polymers can be used in combination as appropriate.

Examples of the basic compound used for neutralization include organic amines such as ammonia, methylamine, ethylamine, diethylamine, dimethylethanolamine, diethanolamine and triethanolamine, sodium hydroxide, potassium hydroxide and lithium hydroxide. Alkali metal hydroxides such as. These basic compounds may be used alone or in combination of two or more.
The degree of neutralization with the basic compound may be any degree as long as the degree of neutralization in which the olefin-α, β-unsaturated carboxylic acid copolymer is stably present in the aqueous solvent. For example, it may be 30 to 100 mol%, more preferably 40 to 90 mol% of the carboxyl group of the copolymer.

As the dispersion method, a known method, for example, as a dispersion device using a medium, a paint shaker, a ball mill, an attritor, a basket mill, a sand mill, a sand grinder, a dyno mill, a dispermat, an SC mill, a spike mill, an agitator mill and the like can be used. It can be used and can be dispersed by an ultrasonic homogenizer, a high-pressure homogenizer, a nanomizer, a resolver, a disper, a high-speed impeller disperser, or the like without using a medium.

The solid content of the aqueous dispersion of the olefin-α, β-unsaturated carboxylic acid copolymer used in the present invention is not particularly limited, and has a desired viscosity when applied as a heat sealant and after application of the heat sealant. It may be appropriately determined depending on the drying conditions, the film thickness, and the like. Generally, it is often applied in the range of solid content concentration of 10 to 40% by mass.

(wax)
In the aqueous heat sealant of the present invention, blocking resistance can be maintained by adding wax. Examples of the wax include fatty acid amide wax, carnauba wax, polyolefin wax, paraffin wax, Fisher Tropsch wax, honey wax, microcrystallin wax, polyethylene oxide-wax, wax such as amido wax, coconut oil fatty acid and soybean oil fatty acid. be able to. These may be used alone or in combination.
Of these, fatty acid amide wax, carnauba wax, and Fisher Tropsch wax are preferably used, and fatty acid amide wax and carnauba wax are particularly preferable.
Specific examples of the fatty acid amide wax include pelargonic acid amide, capric acid amide, undecyl acid amide, lauric acid amide, tridecyl acid amide, myristic acid amide, pentadecyl acid amide, palmitic acid amide, heptadecyl acid amide, and stearic acid amide. , Nonadecanic acid amide, araquinic acid amide, behenic acid amide, lignoseric acid amide, oleic acid amide, settreic acid amide, linoleic acid amide, linolenic acid amide, mixtures thereof, animal and vegetable oil and fat fatty acid amides and the like.

Specific examples of the carnauba wax include MICROKLEAR 418 (manufactured by Micro Powders, Inc.), purified carnauba wax No. 1 powder (Nippon Wax Co., Ltd.) and the like.

The amount of the wax blended is preferably 1.5 to 20% by mass with respect to the total amount of the aqueous heat sealant solid content of 100% by mass. If the total amount of wax is 3% by mass or more with respect to the total amount of 100% solid content of the aqueous heat sealant, the blocking resistance tends to be maintained, and the total amount of wax is 15% by mass or less with respect to the total amount of 100% solid content of the aqueous heat sealant. If there is, there is a tendency that the heat sealability can be maintained.

Of the waxes, the combined use of the fatty acid amide wax and the carnauba wax is more preferable because the blocking resistance is further improved. When used in combination, the ratio is not particularly limited, but is preferably in the range of fatty acid amide wax: the carnauba wax = 1: 1 to 1:10, and still more preferably in the range of 1: 1 to 1: 5.

The wax may be directly added to the aqueous dispersion of the olefin-α, β unsaturated carboxylic acid copolymer and mixed and dispersed, or the olefin-α, β unsaturated carboxylic acid copolymer may be used as an aqueous solvent. It may be added at the same time as the dispersion and mixed and dispersed. As the dispersion method, the method used in the above-mentioned method for dispersing the olefin-α, β unsaturated carboxylic acid copolymer in an aqueous solvent can be appropriately used.

When a plurality of types of waxes are used in combination, the plurality of types of waxes may be added at the same time, or may be added separately in a plurality of steps. For example, after adding the first wax when dispersing the olefin-α, β unsaturated carboxylic acid copolymer in the aqueous solvent, the second wax is added to the obtained first wax and the olefin-α, The aqueous heat sealant of the present invention can be obtained by a method of further adding to an aqueous dispersion with a β unsaturated carboxylic acid copolymer.

In addition to the above-mentioned components, the heat-sealing agent of the present invention includes silica, alumina, defoaming agents, viscosity modifiers, leveling agents, tackifiers, preservatives, antibacterial agents, and antibacterial agents as long as the object of the present invention is not impaired. Additives such as rust agents, antioxidants, and silicone oils may be blended.
Further, in the aqueous heat sealant of the present invention, a polymer-based defoaming agent, a silicon-based defoaming agent, and a fluorine-based defoaming agent are preferably used in order to prevent foaming when coating with various coaters. .. As these defoaming agents, both emulsified dispersion type and solubilized type can be used. Of these, a polymer-based defoaming agent is preferable. The amount of the defoaming agent added is preferably 0.005% by weight to 0.1% by weight of the total amount of the aqueous heat sealant.

(Paper container)
The water-based heat sealant of the present invention can be used as a heat sealant when manufacturing a paper container, and the coated portion other than the seal (adhesive) portion functions as a coating agent for imparting waterproofness to the paper. do.
The water-based heat sealant of the present invention can be easily softened by heating with a burner or hot air to bond papers or paper to other materials, and then cooled to solidify the bonded portion to solidify the papers or paper. And other materials can be firmly sealed.

Examples of the material that can be adhered (sealed) by the water-based heat-sealing agent of the present invention include paper, non-woven fabric, and plastic, but paper is preferable. The paper used in the present invention is produced by a known paper machine using natural fibers for papermaking such as wood pulp, but the papermaking conditions thereof are not particularly specified. Examples of natural fibers for papermaking include wood pulp such as coniferous tree pulp and broadleaf tree pulp, non-wood pulp such as Manila hemp pulp, sisal hemp pulp, and flax pulp, and pulp obtained by chemically modifying these pulps. As the type of pulp, chemical pulp, gland pulp, chemi-grand pulp, thermomechanical pulp or the like obtained by a sulfate cooking method, an acidic / neutral / alkaline sulfite cooking method, a soda salt cooking method or the like can be used.

For the paper substrate, the type, thickness, and the like of the paper can be sequentially selected according to the purpose. For example, for burger wraps, it is about 20 grams / m ² for paper density, for paper cups it is 200 to 300 grams / m ² , and for paper plates, paper spoons, paper madler, etc., it is 50 to 500 for paper density. Food base paper such as gram / m ² cup base paper is preferred. From the viewpoint of recycling efficiency and cost reduction, it is preferable that these papers are not laminated with polyethylene-film, aluminum or the like.

The water-based heat sealant of the present invention has a function as an adhesive for adhering two parts of a paper substrate in a superposed state. Specifically, the aqueous heat sealant of the present invention is applied to at least one of the two parts of the paper substrate (which may be both parts) and then softened by heating.

As a method for applying the aqueous heat sealant of the present invention, a known method can be used. For example, roll coater, gravure coater, flexo coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, transfer roll coater, kiss coater, curtain coater, cast coater, spray coater, die coater, offset printing machine, screen printing. Machines can be used. Further, a drying step may be provided in an oven or the like after coating.

As the heating method, a heat source such as a burner, hot air, electric heat, infrared rays, electron beams, or other conventionally known means can be used. Specifically, depending on the method of heating with a burner or hot air, or the form of molding. A heat welding sealing method, an ultrasonic sealing method, or a high frequency sealing method is preferable. The heating temperature at this time is preferably 200 to 500 ° C., and the heating time is preferably 0.1 to 3 seconds.
The water-based heat sealant of the present invention can be easily heated and softened even by non-contact heating, and to some extent even if it is separated from the heat source, other than the method of directly contacting with a heat source such as a heat seal bar to melt it. The heat seal function lasts for a long time. When the base material is paper, the paper may be burnt if it is brought into direct contact with a heat source. It is particularly useful as a heat sealant for industrial production of paper containers that require line speed.

The film thickness of the solid content after coating the aqueous heat sealant of the present invention may be a desired film thickness. For example, when used in a paper container for food, the film thickness is in the range of 2 to 12 g / m ² . The effect of the invention can be sufficiently obtained. Above all, it is more preferably in the range of 5 to 10 g / m ² .

After applying the water-based heat sealant of the present invention to heat and soften the coated portion, the coated portion and another portion are pressure-bonded in a superposed state. The crimping method is not particularly limited, and a hot plate method, an ultrasonic sealing method, or a high frequency sealing method can be used.

On the other hand, even when the aqueous heat sealant of the present invention is used as a coating agent for paper, the film thickness of the solid content after coating on the coated surface may be a desired film thickness, and is used, for example, in a paper container for food. In that case, the effect of the present invention can be sufficiently obtained if the range is 2 to 12 g / m ² . Above all, it is more preferably in the range of 5 to 10 g / m ² .

When the aqueous heat sealant of the present invention is used as a coating agent for paper, it should be coated to a desired film thickness by the above-mentioned coating method, and then dried by a drying method such as heat drying or room temperature drying. Just do it.

Paper containers that can use the water-based heat sealant of the present invention include paper cups, cup noodles, various beverages, desserts such as ice cream, pudding and jelly, rice confectionery, potato chips, chocolate confectionery, snack confectionery such as biscuits, hamburgers and hots. It is widely used for dock wrapping paper, take-out containers such as pizza, hot snack containers such as fried chicken and potatoes, and food paper containers such as cups for delicatessen such as natto.

(Manufacturing method of paper container)
As a specific embodiment for manufacturing a paper container using the aqueous heat sealant of the present invention, for example, a method for manufacturing a paper container such as a paper cup will be specifically described. In the present invention, the present invention is not limited to the specific embodiment, and can be applied to all heat-sealable paper containers.

As a specific embodiment, a cylinder made of a paper base material having a resin layer provided at least on the inner surface of the container and the bonding surface when assembling the container, and the bonded surfaces of the rolled and overlapped ends of the paper substrate are heat-welded. Shaped body member (1) and
Paper having at least a paper base material having a resin layer provided on the inner surface of the container and the bonding surface when assembling the container, and having a plate-shaped bottom member (2) heat-welded to the lower end of the body member (1). The method of manufacturing the container will be described.

Both the cylindrical body member (1) and the plate-shaped bottom member (2) are made by cutting out a paper base material provided with a resin layer into a desired shape, and the heat seal of the present invention is formed on the resin layer. Use an agent.
First, the heat sealant of the present invention is applied to at least the bonded surface, preferably the entire surface of the paper substrate. As the coating method, the above-mentioned coating method can be appropriately used. After coating, the water-based solvent on the coated surface of the heat sealant is removed with a dryer or the like, and then printing is performed as necessary. Printing is often done on the side opposite the heat sealant.

Next, the tubular body member (1) is cut out in a fan shape, and the plate-shaped bottom member (2) is cut out in a circular shape.
The bonded surfaces at both ends of the tubular body member (1) cut out in a fan shape are heated with a heat source such as a burner or hot air to heat and soften the heat sealant, and the bonded surfaces are overlapped and crimped. The order of heating, superimposition, and crimping is not particularly limited. For example, the bonded surfaces may be heated with a heat source and then the surfaces are overlapped with each other, and then crimped, or the bonded surfaces are overlapped with each other and then heated with a heat source. It may be crimped, or it may be heated by a heat source while crimping after overlapping the bonded surfaces. A method in which the bonded surfaces are heated with a heat source, the surfaces are overlapped with each other, and then pressure-bonded is preferable because the heat sealant is surely heated and softened. The heating temperature at this time is preferably 200 to 500 ° C., and the heating time is preferably 0.1 to 3 seconds. As a result, a tubular body member having the heat sealant coated surface inside can be obtained. As the fan-shaped paper base material, a machine called a blanker that punches out the paper base material into a fan shape may be used, and a blank (body portion) of a paper container can be produced.

On the other hand, the bottom member (2) cut out in a circular shape is installed inside the tubular body member so that the surface coated with the heat sealant is inside the cup, and then the bottom member and the body member come into contact with each other. The portion is heated with a heat source to soften and bond the heat sealant on the bottom member side and the body member side in the same manner as described above. At this time, the heat sealant softens and fills the gap between the bottom member and the body member, so that water leakage or the like does not occur.

In the production of the paper cup, a paper cup can be obtained by a known process, for example, a method in which the lower end of the bottom side of the body member is folded inward and crimped with a rotating circular mold to finish the bottom of the paper cup. When finishing, the heat-sealed portion may be heated by the above-mentioned heat source in order to strengthen the connection between the body member and the bottom member, if necessary. Finally, the portion corresponding to the drinking spout at the upper end of the body member is subjected to a molding process called curling, in which the tool is wound around the outside of the paper cup while rotating the tool as necessary.

The paper container of the specific embodiment is mainly a cup-shaped container having a disk-shaped bottom member, but the shape is not limited to this, for example, a rectangular parallelepiped or polygonal bottom member having a rectangular parallelepiped shape. Alternatively, it may be a cube-shaped container. Further, if necessary, the container is sealed with a separately manufactured lid material or the like, and for example, when heating in a microwave oven or the like, the lid material is removed or a part of the container is opened and used. May be good.

Hereinafter, the present invention will be described in detail based on examples, but the technical scope of the present invention is not limited to these embodiments.

<Method for producing olefin-α, β unsaturated carboxylic acid copolymer>
(Manufacturing Example 1)
77.8 parts of ethylene, 11.1 parts of ethyl acrylate, and 11.2 parts of acrylic acid were synthesized by a conventional method to obtain an ethyl acrylate-acrylic acid copolymer.
Twenty-five parts of the obtained copolymer, ammonia having a neutralization rate of 100% with respect to the acid value of the copolymer, and water as an aqueous solvent were charged and stirred to form both olefin-α and β unsaturated carboxylic acids. An aqueous dispersion (A1) of the polymer was obtained.

(Manufacturing Example 2)
77.8 parts of ethylene, 11.1 parts of ethyl acrylate, and 11.2 parts of acrylic acid were synthesized by a conventional method to obtain an ethyl acrylate-acrylic acid copolymer.
Twenty-five parts of the obtained copolymer, ammonia having a neutralization rate of 100% with respect to the acid value of the copolymer, water as an aqueous solvent, and 1.5 parts of fatty acid amide wax as a wax were charged and stirred to form an olefin. An aqueous dispersion (A2) of a -α, β unsaturated carboxylic acid copolymer and a fatty acid amide wax was obtained.

<Preparation of water-based heat sealant>
(Examples 1 to 8 and Comparative Examples 1 to 7)
The aqueous dispersion (A1) or (A2) obtained in Production Example 1 or Production Example 2 was used to obtain an aqueous heat sealant of Example or Comparative Example according to the composition of Table 1 or 2.

<Evaluation>
(Heat sealability)
The aqueous heat sealant of Example or Comparative Example was applied to a cup base paper (manufactured by Nippon Paper Industries, Ltd.) using a bar coater # 16, and then dried at 100 ° C. for 30 seconds. After that, cut the coated paper to 3.0 cm x 5.0 cm, temporarily fix the short surface with two tapes so that the coated surface and the non-coated surface are in close contact with each other with a width of 5 mm, and heat one side with a hot plate for 5 seconds. Immediately without heating, heat-sealing was performed using a heat-sealing machine under 1 kgf / m ² , 1-second adhesion conditions, and the adhesion status was visually evaluated, and then the minimum temperature of the hot plate that was completely adhered was investigated.
6: Fully adhere at 200 ° C.
5: Fully adhere at 210 ° C.
4: Fully adhere at 220 ° C.
3: Completely adhere at 230 ° C.
2: Fully adhere at 240 ° C.
Does not adhere even at 1: 240 ° C or higher.

(Water resistance of the seal part)
Water was dripped on the sheet-sealed seal portion by the heat sealability evaluation method, and the degree of water leakage from the seal portion was visually confirmed.
4: No water leakage at all.
3: A very slight water leak is seen partially.
2: A slight water leak is seen partially.
1: Water leaks are seen over the entire surface.

(Slippery)
The aqueous heat sealant of Example or Comparative Example was applied to a cup base paper (manufactured by Nippon Paper Industries, Ltd.) using a bar coater # 16, and then dried at 100 ° C. for 30 seconds. After that, the coated paper was cut into 3.0 cm × 5.0 cm to obtain a test piece. Several sheets of the test piece were placed on top of each other so that the coated surface and the non-coated surface were in contact with each other, and a sample was taken from only the upper one, and the behavior of the test piece at that time was visually confirmed.
4: When the test pieces are stacked, the test pieces can be taken one by one.
3: There is a behavior that the lower test piece is attached to the upper test piece very slightly.
2: Occasionally, there is a behavior that the lower test piece is attached to the upper test piece.
1: The lower test piece is attached to the upper test piece.

(Blocking resistance)
(Blocking resistance)
The coated surface and the non-coated surface of the coated paper prepared by the evaluation of heat sealability are overlapped so as to be in contact with each other, a load of 10 kgf / cm ² is applied, the paper is allowed to pass for 48 hours in an environment of 40 ° C. The degree of adhesion between the work surface and the uncoated surface was visually evaluated in the following four stages.
(Evaluation criteria)
4: No blocking is seen.
3: Partial blocking is seen.
2: Partial blocking is seen.
1: Blocking is seen over the entire surface.

(Recyclability)
Cut the coated papers of Examples 1 to 8 prepared in the evaluation of heat sealability into 3.0 cm × 5.0 cm, put them in a 1% by mass aqueous solution of sodium hydroxide, and use a paint shaker (Asada Iron Works Co., Ltd.) for 30 minutes. When the state after stirring was confirmed, the paper was sufficiently dissociated and no film-like substance was confirmed.
On the other hand, when a commercially available paper cup was cut into 3.0 cm × 5.0 cm and the same evaluation was performed, it was confirmed that a film-like material remained. Therefore, it was confirmed that the polyethylene film obtained in the examples remained in the form of a sheet.
Therefore, it can be seen that the coated papers of Examples 1 to 8 do not reduce the paper recycling efficiency.

The evaluation results of the laminated bodies of Examples 1 to 8 and Comparative Examples 1 to 7 are shown in Tables 1 and 2.

In the table, the abbreviations are as follows.
Styrene-acrylic resin: Neocryl A-2095 (Kusumoto Kasei Co., Ltd.)
Carnauba wax: MICROKLEAR 418 (Micro Powders, Inc.)
Fisher Trofish Wax (a): MP-22XF (Micro Powders, Inc.)
Fisher Trofish Wax (b): MP-28C (Micro Powders, Inc.)
Fine powder polyethylene: Frosen uF1.5N (Sumitomo Seika Co., Ltd.)

Claims (4)

Contains an aqueous solvent, an olefin-α, β unsaturated carboxylic acid copolymer and a wax,
The content of α, β unsaturated carboxylic acid in the olefin-α, β unsaturated carboxylic acid copolymer is 8 to 24% by mass.
The wax is one or more selected from fatty acid amide wax, carnauba wax and Fischer-Tropsch wax.
A water-based heat sealant characterized by that. A paper container paper base material comprising the water-based heat sealant according to claim 1 on at least one side of the paper base material. A paper container having the water-based heat sealant according to claim 1 on at least one side of the paper base material. A paper container using a paper base material. A tubular body member made of a paper base material having a resin layer provided at least on the inner surface of the container and the bonding surface when assembling the container, and the bonding surfaces of the rolled and overlapped ends of the paper substrate are heat-welded. 1) and
Paper having at least a paper base material having a resin layer provided on the inner surface of the container and the bonding surface when assembling the container, and having a plate-shaped bottom member (2) heat-welded to the lower end of the body member (1). It ’s a container manufacturing method.
A method for manufacturing a paper container, wherein the resin layer is made of the dry coating film of the aqueous heat sealant according to claim 1 .