KR20240066626A - Coating composition for paper containers and paper containers using the same - Google Patents

Abstract

The present invention relates to a coating composition for paper containers and a paper container using the same. Specifically, the polyvinyl alcohol contained in the coating composition for paper containers is modified to prevent mixing with other coating solutions, and the polyvinyl alcohol contained in the coating composition for paper containers is modified to prevent mixing with other coating solutions, including inorganic nanoparticles. It relates to a coating composition for paper containers that improves resistance to heat, improves storage stability, and reduces cross-linking time, and to paper containers using the same.

Description

Coating composition for paper containers and paper containers using the same {COATING COMPOSITION FOR PAPER CONTAINERS AND PAPER CONTAINERS USING THE SAME}

The present invention relates to a coating composition for paper containers and a paper container using the same. Specifically, the polyvinyl alcohol contained in the coating composition for paper containers is modified to prevent mixing with other coating solutions, and the polyvinyl alcohol contained in the coating composition for paper containers is modified to prevent mixing with other coating solutions, including inorganic nanoparticles. It relates to a coating composition for paper containers that improves resistance to heat, improves storage stability, and reduces cross-linking time, and to paper containers using the same.

Food packaging materials require physical properties to prevent deterioration of food by blocking oxygen and moisture from the outside or blocking moisture and odor from the inside to preserve the contents for a long period of time and maintain the characteristics such as freshness and moisture content of the product.

Conventional technology used polymer-based films coated with aluminum or minerals, but efforts to replace them continued due to problems such as recycling. As part of these efforts, a barrier film such as polyethylene can be laminated on one or both sides of an easily recyclable paper substrate. However, although it has excellent moisture barrier properties, it is not suitable for use in food packaging due to its poor oxygen barrier properties. In addition, recycling is limited due to the polyethylene coating film. Therefore, in order to block oxygen, a paper substrate can be coated with a polymer such as metal such as aluminum or nylon or EVOH, but this also has problems in terms of recycling and price. In addition, the PVDC coating film shows excellent blocking properties for both moisture and oxygen, but it has the disadvantage of being difficult to recycle due to the poor dissociation characteristics of the packaging paper during recycling, and may emit environmental pollutants when disposed of or incinerated.

Recently, the development of a PVA-based coating layer has been conducted considering price and recycling aspects, but it is insufficient to secure sufficient oxygen and moisture barrier properties for use in food packaging.

PVA contains many hydroxyl groups in the molecular chain, so the hydrogen bonds between molecules are strong. Through this strong interaction, the polymer chains are closely bonded to form a thin film, which makes it difficult for gases such as oxygen to pass through. However, the hydroxyl group of PVA easily forms hydrogen bonds with moisture or water vapor, and as a result, moisture or water vapor easily diffuses on the thin film, showing very low moisture permeability. Therefore, paper packaging coated with PVA has almost no moisture barrier properties, and when coated on the inside, the shape of the film is deformed due to moisture in the food, etc., so it is not suitable as a coating material for food packaging.

On the other hand, general polymer thin films such as acrylic or olefin do not form a dense thin film and have poor blocking properties for oxygen or nitrogen, but have relatively excellent moisture blocking properties due to their hydrophobicity.

Accordingly, in Republic of Korea registered patents 10-1195209, 10-1752340, and 10-2271563, an acrylic emulsion with excellent moisture barrier properties was used simultaneously with PVA to improve the moisture barrier properties of PVA. However, the disclosed method mixes PVA and acrylic emulsion, and this type of coating film deteriorates both the oxygen barrier properties of PVA and the moisture barrier properties of the acrylic layer. In other words, the PVA and acrylic mixed thin film has lower density, resulting in higher gas permeability, and PVA increases the hydrophilicity of the thin film, resulting in increased moisture permeability.

In Japanese registered patent 5331265, the above problems can be solved by sequentially coating a paper substrate with a PVA aqueous solution and an acrylic and latex mixed emulsion solution. However, in the updated method, the acrylic emulsion is first coated on a paper substrate and then a PVA layer is formed. Finally, packaging materials are manufactured by laminating polyethylene, etc. to protect the PVA and secure sealing properties. However, although this method may have excellent moisture and oxygen blocking properties, it has the disadvantage of being difficult to recycle due to polyethylene. In addition, when PVA is coated on a paper substrate and then an acrylic emulsion is coated, a polyethylene film may not be formed, but there are limitations in terms of the process because PVA may be dissolved and mixed during acrylic emulsion coating.

These problems can be solved by chemically or physically crosslinking PVA. Existing PVA chemical crosslinking methods have been studied in various ways, including methods using boric acid derivatives, dialdehyde, typically glutaraldehyde, cupric acetate, or weak Lewis acids such as aluminum chloride, zirconium chloride, and titanium chloride. It can be crosslinked. However, in this method, if the reaction time of the cross-linking agent is short, gelation of the coating solution mixed with PVA and cross-linking agent occurs. In other words, there is a problem with the storage stability of the coating solution, and for storage stability, a crosslinking agent that hardly reacts at room temperature requires a crosslinking reaction time of more than 1 hour at around 100°C. However, the storage stability and long reaction time of these coating solutions are not suitable due to productivity issues in the roll-to-roll process mainly used to produce paper packaging materials. In other words, in terms of productivity, the solution stability of the coating solution requires that the physical properties (viscosity, etc.) do not change for several hours to several days, and the crosslinking reaction must sufficiently occur during the drying time of several seconds to several minutes after coating.

The technical problem to be achieved by the present invention is that it can be used as a gas for food packaging, that is, an oxygen and moisture barrier film, that can be applied to an eco-friendly manufacturing process that does not use organic solvents, and has recyclable dissociation properties and is harmless to the human body when applied to food. In addition, the present invention provides a coating composition for paper containers that can provide sealing properties and maximize moisture barrier properties, and paper containers using the same.

However, the problem to be solved by the present invention is not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

One embodiment of the present invention includes carboxylic acid-modified PVA, inorganic nanoparticles, and a solvent, wherein the carboxylic acid-modified PVA is a reaction product of a mixture containing an aqueous PVA solution and an acrylic acid derivative containing a carboxylic acid group. A coating composition for use is provided.

According to one embodiment of the present invention, the carboxylic acid-modified PVA may include a repeating unit represented by Formula 1 below and a repeating unit represented by Formula 2 below.

[Formula 1]

[Formula 2]

R ₁ is hydrogen, a straight-chain or branched alkyl group having 1 to 20 carbon atoms, or an aromatic group having 1 to 20 carbon atoms, and the "*" indicates a connection point.

According to one embodiment of the present invention, the content of the acrylic acid derivative containing the carboxylic acid group may be 1 mole part or more and 50 mole parts or less with respect to 100 mole parts of the PVA aqueous solution.

According to one embodiment of the present invention, the mixture further includes a radical initiator, and the radical initiator may be an azo-based radical initiator, a peroxide-based radical initiator, or a combination thereof.

According to one embodiment of the present invention, the content of the radical initiator may be 2 mole parts or more and 80 mole parts or less with respect to 100 mole parts of the acrylic acid derivative containing the carboxylic acid group.

According to one embodiment of the present invention, the solid content of the carboxylic acid-modified PVA may be 1% by weight or more and 20% by weight or less.

According to one embodiment of the present invention, the coating composition for a paper container further includes an antifoaming agent, and the content of the antifoaming agent may be 0.1 part by weight or more and 3 parts by weight or less based on 100 parts by weight of the coating composition for a paper container.

According to one embodiment of the present invention, the content of the inorganic nanoparticles may be 0.1 part by weight or more and 30 parts by weight or less based on 100 parts by weight of solid content of the carboxylic acid-modified PVA.

According to one embodiment of the present invention, the coating composition for a paper container may further include a metallic crosslinking agent.

According to one embodiment of the present invention, the content of the metallic crosslinking agent may be 0.01 equivalent or more and 5 equivalents or less based on the equivalent weight of the carboxylic acid group of the carboxylic acid-modified PVA.

One embodiment of the present invention includes a paper substrate (110); A first coating layer 130 provided on one side of the paper substrate 110 and being a dried product of the coating composition for a paper container; and a second coating layer 150, which is provided on one side of the first coating layer 130 opposite to the side on which the paper substrate 110 is provided, and is a dried product of a mixture containing an acrylic resin. Provides (100).

According to one embodiment of the present invention, the solid content of the first coating layer 130 may be 1 g/m ² or more and 20 g/m ² or less.

According to one embodiment of the present invention, the solid content of the second coating layer 150 may be 1 g/m ² or more and 10 g/m ² or less.

According to an exemplary embodiment of the present invention, the first coating layer 130 may be 2 or more layers and 10 or less layers.

According to one embodiment of the present invention, the second coating layer 150 may be further provided on the other side of the paper substrate 110, which is opposite to the one side provided with the first coating layer 130.

The paper coating composition according to an embodiment of the present invention improves resistance to water, can be applied to an eco-friendly manufacturing process that does not use organic solvents, has dissociation properties to enable recycling, and can be used in food packaging containers. Even when used, it can achieve characteristics that are harmless to the human body.

The paper container according to an embodiment of the present invention can improve resistance to water, provide sealing properties, maximize moisture barrier properties, and implement oxygen barrier properties at the same time.

The effect of the present invention is not limited to the above-mentioned effect, and effects not mentioned will be clearly understood by those skilled in the art from the present specification and the attached drawings.

Figure 1 (a) is a schematic diagram of the reaction product of a coating composition for a paper container according to an exemplary embodiment of the present invention and a metallic crosslinking agent containing a divalent cation.
Figure 1 (b) is a schematic diagram of the reaction product of a coating composition for a paper container according to an exemplary embodiment of the present invention and a metallic crosslinking agent containing a trivalent cation.
Figure 2 is a schematic diagram of a cut surface of a paper container 100 according to an exemplary embodiment of the present invention.
Figure 3 is a schematic diagram of a cut surface of a paper container 100 according to an exemplary embodiment of the present invention.
Figure 4 is a schematic diagram of a cut surface of a paper container 100 according to an exemplary embodiment of the present invention.

Throughout the specification of the present application, when it is said that a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

Throughout this specification, any member may be "on" another member. When said to be located, this includes not only cases where a member is in contact with another member, but also cases where another member exists between the two members.

Throughout the specification herein, the unit "part by weight" may refer to the ratio of weight between each component.

Throughout this specification, "A and/or B" means "A and B, or A or B."

Throughout this specification, the "weight average molecular weight" of a compound is used. and "number average molecular weight" can be calculated using the molecular weight and molecular weight distribution of the compound. Specifically, tetrahydrofuran (THF) and a compound were placed in a 1 ml glass bottle to prepare a sample sample with a compound concentration of 1 wt%, and the standard sample (polystyrene) and sample sample were filtered (pore size). After filtering through 0.45㎛, it is injected into a GPC injector, and the molecular weight and molecular weight distribution of the compound can be obtained by comparing the elution time of the sample with the calibration curve of the standard sample. At this time, Infinity II 1260 (Agilient) can be used as a measuring instrument, the flow rate can be set to 1.00 mL/min, and the column temperature can be set to 40.0 ℃.

Hereinafter, the present invention will be described in detail.

In order to apply it to paper containers used in food packaging, it is necessary to form a film that has both oxygen barrier properties and moisture barrier properties. To this end, a first coating layer 130 with oxygen barrier properties and moisture barrier properties is applied to the paper substrate 110. The branches include a second coating layer 150, where the first coating layer 130 is coated on the paper substrate 110 and the second coating layer 150 needs to be formed on the first coating layer 130.

In the present invention, the first coating layer 130 has oxygen blocking properties to maintain food quality and prevent spoilage, and the second coating layer 150 has moisture blocking properties and heat sealing properties for sealing. It is characterized by In addition, the packaging must have excellent dissociation properties so that it can be recycled after use. Therefore, the paper substrate 110 with excellent dissociability was selected so that both the first coating layer 130 and the second coating layer 150 could be recycled.

Furthermore, due to the nature of the paper industry, roll-to-roll coating must be applied for mass production, and due to worker safety and environmental issues, the coating solution, that is, the main solvent of the coating composition, is required to be water. Therefore, the coating composition must use an aqueous solution or an aqueous dispersion-based solution to ensure an eco-friendly process. In the present invention, in order to satisfy such process conditions, water is used as a solvent for both the coating composition for producing the first coating layer 130 and the coating composition for forming the second coating layer 150, and the coating composition for forming the second coating layer 150 is used as a solvent. In the process of forming (150), it must have the characteristic of not dissolving in water after forming the first coating layer 130 to prevent mixing with the first coating layer 130 and to separate the layers. That is, after forming the first coating layer 130 using an aqueous solution-based coating composition for manufacturing the first coating layer 130, a crosslinking reaction was performed so as not to dissolve in water.

In addition, due to the nature of the roll-to-roll process, a crosslinking method that requires a long crosslinking time is not suitable, so the crosslinking reaction must be completed upon drying and must have neutral water resistance or insolubility. In order to secure these properties, it is necessary to introduce a cross-linking system that can be applied to a short drying process. In the present invention, an ionic cross-linking method was used for this cross-linking, enabling the formation of an effective PVA cross-linking film through improvement of the coating process.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention includes carboxylic acid-modified PVA, inorganic nanoparticles, and a solvent, wherein the carboxylic acid-modified PVA is a reaction product of a mixture containing an aqueous PVA solution and an acrylic acid derivative containing a carboxylic acid group. A coating composition for use is provided.

The paper coating composition according to an embodiment of the present invention improves resistance to water, can be applied to an eco-friendly manufacturing process that does not use organic solvents, has dissociation properties to enable recycling, and can be used in food packaging containers. Even when used, it can achieve characteristics that are harmless to the human body.

According to an exemplary embodiment of the present invention, it includes carboxylic acid-modified PVA, inorganic nanoparticles, and a solvent. As described above, by containing carboxylic acid-modified PVA, inorganic nanoparticles, and a solvent, the carboxylic acid-modified PVA is cross-linked with a metallic cross-linker to be described later, and the mixture containing the acrylic resin for the second coating layer to be described later is formed to be the first coating layer to be described later. By preventing mixing with the coating layer, moisture and oxygen barrier properties are improved, the water resistance of the first coating layer is improved, and an eco-friendly manufacturing process can be implemented during the coating process.

According to one embodiment of the present invention, the coating composition for a paper container includes the carboxylic acid-modified PVA. As described above, the coating composition for paper containers includes the carboxylic acid-modified PVA, thereby introducing a carboxylic acid group into the PVA chain to form a form that can bind to various metal ions, and at the same time, effective ionic crosslinking. .

According to one embodiment of the present invention, the solvent may be an aqueous solution. As described above, by using an aqueous solution as the solvent, the coating process can be implemented in an environmentally friendly manner.

According to one embodiment of the present invention, the carboxylic acid-modified PVA is a reaction product of a mixture containing an aqueous PVA solution and an acrylic acid derivative containing a carboxylic acid group. Specifically, the carboxylic acid-modified PVA may be a reaction product produced by a radical reaction between a PVA aqueous solution and a compound containing an acrylic acid derivative containing a carboxylic acid group. As described above, by using the carboxylic acid-modified PVA as a reaction product of a mixture containing an aqueous PVA solution and an acrylic acid derivative containing a carboxylic acid group, the radical reaction can be implemented at a relatively low temperature, and all that is required is the introduction of a carboxylic acid functional group. In addition, the viscosity and crosslinking degree of the carboxylic acid-modified PVA can be adjusted and water resistance can be improved.

According to one embodiment of the present invention, the solvent used in the reaction between PVA and an acrylic acid derivative containing a carboxylic acid group may be water. As described above, an eco-friendly process can be implemented by selecting water as the solvent used in the reaction between PVA and an acrylic acid derivative containing a carboxylic acid group.

According to one embodiment of the present invention, the water content may be 500 parts by weight or more and 1900 parts by weight or less based on 100 parts by weight of the PVA. By adjusting the water content within the above-mentioned range, the drying speed can be adjusted.

According to one embodiment of the present invention, the carboxylic acid-modified PVA may be capable of thermal crosslinking (self-esterification). Metal chelate type crosslinking may be possible using a metallic crosslinking agent, which will be specifically described later. As described above, by implementing the carboxylic acid-modified PVA as capable of thermal crosslinking (self-esterification), it is prevented from deteriorating both oxygen and moisture barrier properties due to mixing of the mixture containing the acrylic resin, which will be described later, with the first coating layer, which will be described later. can do.

According to one embodiment of the present invention, the PVA may be fully saponified or partially saponified PVA, and PVA copolymerized with ethylene, such as ethylene, may be used. Specifically, the PVA is manufactured by Dow DuPont, Eastman Chemical, Japan Synthetic Chemical Industry, Celanese Corporation, OCI Co., Ltd., Solutia Co., Ltd., Sinopec Group, Kuraray, Sekisui Chemical Co., Ltd., Jangjeong Petrochemical Co., Ltd., Japan VAM & Commercial products manufactured by Poval, Sekisui Chemical Co., Ltd., Merck KGaA, Anhui Wanwei Group and other companies can be used, and various grades of PVA can be used. More specifically, various grades of PVA classified according to viscosity, saponification, ASH (MAX%), volatility (MAX%), and pH, such as OCI's POLINOL P05, P17, P20, P24, F17, CL05A, M17, etc. There are PVA product lines classified according to form, such as Kuraray's EXCEVAL, POVAL, ELVANOL, and MOWIFLEX, and various grades of PVA subdivided according to viscosity, saponification, ASH (MAX%), volatility (MAX%), and pH within the product line. can be used.

According to one embodiment of the present invention, the saponification degree (saponification degree) of the PVA may be 76 mol% or more and 100 mol% or less. Specifically, the degree of saponification (degree of saponification) of the PVA may be 85 mol% or more and 89 mol% or less, or 98 mol% or more and 99 mol% or less. More specifically, the saponification degree (saponification degree) of the PVA can be adjusted by considering the type of acrylic acid derivative containing the carboxylic acid group to be used, coating properties, adhesion, tensile strength, solvent resistance, and moisture resistance. By adjusting the saponification degree (saponification degree) of the PVA within the above-mentioned range, the oxygen blocking property can be improved.

According to one embodiment of the present invention, the number average degree of polymerization of the PVA may be 300 or more and 4000 or less. Specifically, it is preferable that the number average degree of polymerization of the PVA is 1500 or more and 3500 or more. More specifically, the number average degree of polymerization of the PVA can be adjusted in consideration of the type of acrylic acid derivative containing the carboxylic acid group to be used, coating properties, adhesion, tensile strength, solvent resistance, and moisture resistance. By adjusting the number average degree of polymerization of the PVA within the above-mentioned range, it is possible to achieve high oxygen blocking properties.

According to one embodiment of the present invention, the solid content of the PVA in the PVA aqueous solution may be 1% by weight or more and 90% by weight or more. By adjusting the solid content of the PVA in the PVA aqueous solution as described above, the physical properties of the first coating layer can be adjusted, workability can be improved, and viscosity can be adjusted.

According to one embodiment of the present invention, the carboxylic acid-modified PVA may include a repeating unit represented by Formula 1 below and a repeating unit represented by Formula 2 below.

[Formula 1]

[Formula 2]

R ₁ is hydrogen, a straight-chain or branched alkyl group having 1 to 20 carbon atoms, or an aromatic group having 1 to 20 carbon atoms, and the "*" indicates a connection point.

As described above, the carboxylic acid-modified PVA is implemented as containing a repeating unit represented by Formula 1 and a repeating unit represented by Formula 2, thereby forming a coating layer in a short time by performing crosslinking with a metallic crosslinking agent. can do.

According to an exemplary embodiment of the present invention, R ₁ in Formula 2 may be hydrogen, a substituted or unsubstituted straight-chain or branched alkyl group having 1 to 20 carbon atoms, and aromatic, and R ₁ in Formula 2 may be It may be 1 mole part or more and 50 mole parts or less per 100 parts by weight of PVA. As described above, by selecting R ₁ of Formula 2 above, the copolymerization reaction can be facilitated.

According to one embodiment of the present invention, the acrylic acid derivative containing the carboxylic acid group may be a derivative having a (meth)acrylic group and a carboxylic acid group at the end of the aliphatic compound. The aliphatic compound may be a cyclic aliphatic compound, an acyclic aliphatic compound, or a compound having an aliphatic side chain. Specifically, acrylic acid derivatives containing the carboxylic acid group include methyl acrylic acid, ethyl acrylic acid, 1-propyl acrylic acid, 1-butyl acrylic acid, Straight-chain or branched-chain alkyl groups with 1 to 20 carbon atoms, such as 2-propyl acrylic acid, 2-butyl acrylic acid, and t-butyl acrylic acid, or 2-phenyl It may be aromatic, such as 2-phenyl acrylic acid or 3-phenyl acrylic acid. From the above, by selecting an acrylic acid derivative containing the carboxylic acid group, the side chain of the PVA can be modified with a carboxylic acid group, and by modifying the PVA with the carboxylic acid group, the coating process can be implemented to be suitable for the roll-to-roll process through an ionic crosslinking reaction. .

According to one embodiment of the present invention, the content of the acrylic acid derivative containing the carboxylic acid group may be 0.1 part by weight or more and 50 parts by weight or less based on 100 parts by weight of the PVA aqueous solution. Specifically, the content of the acrylic acid derivative containing the carboxylic acid group may be 0.5 parts by weight or more and 30 parts by weight or less based on 100 parts by weight of the PVA aqueous solution. By adjusting the content of the acrylic acid derivative containing the carboxylic acid group within the above-mentioned range, the degree of cross-linking of the coating layer can be adjusted and the gelation reaction can be prevented.

According to one embodiment of the present invention, the content of the acrylic acid derivative containing the carboxylic acid group may be 1 mole part or more and 50 mole parts or less with respect to 100 mole parts of the PVA. Specifically, the content of the acrylic acid derivative containing the carboxylic acid group may be 5 mole parts or more and 30 mole parts or less with respect to 100 mole parts of the PVA. By adjusting the content of the acrylic acid derivative containing the carboxylic acid group within the above-mentioned range, the degree of cross-linking of the coating layer can be adjusted and the gelation reaction can be prevented.

According to one embodiment of the present invention, as a means for transferring heat in the process of manufacturing the carboxylic acid-modified PVA solution, a direct heat transfer method to a reaction vessel including a heating mantle, a heating plate, etc. can be applied. there is. Specifically, it is desirable to use a constant temperature circulator using a double jacket reaction vessel. By selecting a means for transferring the heat from the above, the heat can be transferred uniformly.

According to one embodiment of the present invention, the mixture further includes a radical initiator, and the radical initiator may be an azo-based radical initiator, a peroxide-based radical initiator, or a combination thereof.

According to one embodiment of the present invention, specifically, the azo-based radical initiator is 4,4-azobis(4-cyanovaleric acid), 2, 2-(Azobis-[2-(2-imidazolin-2-yl)propane]dihydrochloride (2,2-Azobis-[2-(2-imidazolin-2-yl)propane] Dihydrochloride), It may include the azo-based radical initiator as described above, such as 2,2-azobis (2-methylpropionamidine) dihydrochloride. By doing so, the monomer can be easily polymerized.

According to one embodiment of the present invention, the peroxide-based radical initiator may be a persulfate initiator such as potassium persulfate, sodium persulfate, or ammonium persulfate. The persulfate initiator can be used together with a radical initiation reaction auxiliary agent to help generate radicals and initiate the reaction of an acrylic acid derivative containing a carboxylic acid group, as shown in Scheme 1 below.

[Scheme 1]

As described above, by including a peroxide-based radical initiator, monomers can be easily polymerized.

According to one embodiment of the present invention, the peroxide-based radical initiator may be used together with a radical initiation reaction auxiliary. Specifically, the radical initiation reaction auxiliary may be bisulfite, sodium bisulfite, etc. By including a radical initiation reaction auxiliary as described above, the radical reaction can be promoted.

According to one embodiment of the present invention, the weight ratio of the radical initiator and the radical initiation reaction auxiliary may be 3:1 to 1:3. The radical reaction can be promoted by adjusting the weight ratio of the radical initiator and the radical initiation reaction auxiliary within the above-mentioned range.

According to one embodiment of the present invention, the molar ratio of the radical initiator and the radical initiation reaction auxiliary may be 2:1 to 1:2. The radical reaction can be promoted by adjusting the weight ratio of the radical initiator and the radical initiation reaction auxiliary within the above-mentioned range.

According to one embodiment of the present invention, the content of the radical initiator may be 2 mole parts or more and 80 mole parts or less with respect to 100 mole parts of the acrylic acid derivative containing the carboxylic acid group. Specifically, the content of the radical initiator may be 20 mole parts or more and 80 mole parts or less based on 100 mole parts of the acrylic acid derivative containing the carboxylic acid group. By adjusting the content of the radical initiator within the above-mentioned range, it is possible to easily form a single copolymer rather than chain growth of the acrylic acid derivative containing the carboxylic acid group.

According to one embodiment of the present invention, the content of the radical initiator may be 100 parts by weight or more and 200 parts by weight or less based on 100 parts by weight of the acrylic acid derivative containing the carboxylic acid group. Specifically, the content of the radical initiator may be 110 parts by weight or more and 190 parts by weight or less based on 100 parts by weight of the acrylic acid derivative containing the carboxylic acid group. By adjusting the content of the radical initiator within the above-mentioned range, it is possible to easily form a single copolymer rather than chain growth of the acrylic acid derivative containing the carboxylic acid group.

According to one embodiment of the present invention, the solid content of the carboxylic acid-modified PVA may be 1% by weight or more and 20% by weight or less. By adjusting the solid content of the carboxylic acid-modified PVA within the above-mentioned range, the solubility of the carboxylic acid-modified PVA can be adjusted.

According to one embodiment of the present invention, the coating composition for a paper container may further include an antifoaming agent. As described above, the coating composition for a paper container further includes an antifoaming agent, thereby improving the defoaming effect of the carboxylic acid-modified PVA.

According to one embodiment of the present invention, the antifoaming agent may be a fatty acid-based defoamer containing a fatty acid having 1 to 30 carbon atoms or more carbon atoms, a silicone-based antifoaming agent, or an alcohol-based antifoaming agent containing an alkyl group having 1 to 10 carbon atoms. Specifically, the fatty acid-based antifoaming agent includes decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid. , mineral oil, oxystearin, etc., and the silicone-based antifoaming agent may be dimethyl polysiloxane, silicon dioxide, sorbitanmonostearate, silicon resin, etc. , the alcohol-based antifoaming agent containing the alkyl group is pentyl alcohol, hexyl alcohol, octyl alcohol, isobutyl alcohol, isooctyl alcohol, and butyl alcohol. alcohol), sec-butyl alcohol, etc. By selecting the antifoaming agent from the above, the defoaming effect of the carboxylic acid modified PVA can be improved.

According to one embodiment of the present invention, the content of the antifoaming agent may be 0.1 part by weight or more and 3 parts by weight or less based on 100 parts by weight of the coating composition for a paper container. By adjusting the content of the antifoaming agent within the above-mentioned range, the defoaming effect can be improved.

According to one embodiment of the present invention, the antifoaming agent may further include polysaccharide. Specifically, the polysaccharide may be selected from the group consisting of chitosan, cellulose nanocrystals, cellulose nanofibers, modified cellulose, chitin, and combinations thereof. More specifically, the polysaccharide additive is preferably chitosan, cellulose nanofiber, chitin, etc. By selecting the polysaccharide from the above, chitosan has low solubility in water, but becomes water-soluble and can improve the antibacterial effect as the amino group is cationized to an ammonia group in dilute acid. Cellulose nanofibers are flexible and have a high aspect ratio, which can enhance the gas barrier effect. Chitin can block gases more effectively by making the bonds between particles denser.

According to one embodiment of the present invention, the coating composition for a paper container includes inorganic nanoparticles. As described above, the coating composition for a paper container includes inorganic nanoparticles, thereby providing the coating layer with resistance to water and ensuring adhesion with the acrylic layer formed on the first coating layer.

According to one embodiment of the present invention, the content of the inorganic nanoparticles may be 0.1 part by weight or more and 30 parts by weight or less based on 100 parts by weight of solid content of the carboxylic acid-modified PVA. Specifically, the content of the inorganic nanoparticles is preferably 5 parts by weight or more and 15 parts by weight or less based on 100 parts by weight of solid content of the carboxylic acid-modified PVA. By adjusting the content of the inorganic nanoparticles within the above-mentioned range, resistance to water can be imparted and the second coating layer can be uniformly formed.

According to one embodiment of the present invention, the inorganic nanoparticle may be one selected from the group consisting of metal carbonate, metal silicate, metal oxide, and combinations thereof. Specifically, the metal carbonate is calcium carbonate, magnesium carbonate, etc., the metal silicate is aluminum silicate, calcium silicate, etc., and the metal oxide is zinc oxide ( Zinc oxide, calcium oxide, magnesium oxide, silicon dioxide, etc. may be used. By selecting the inorganic nanoparticles from those described above, antibacterial properties can be imparted.

According to one embodiment of the present invention, the average size of the inorganic nanoparticles may be 10 nm or more and 100 nm or less. Specifically, the average size of the inorganic nanoparticles may be 10 nm or more and 50 nm or less. More specifically, it is preferable that the average size of the inorganic nanoparticles is 20 nm or more and 30 nm or less. In this specification, the “size of the particle” may mean the maximum distance between a straight line crossing the inside of the particle and two points where the particle meets. By adjusting the average size of the inorganic nanoparticles within the above-mentioned range, the dispersibility of the inorganic nanoparticles in the solvent and the barrier performance of the coating layer can be maintained.

According to one embodiment of the present invention, the coating composition for a paper container may further include an inorganic pigment or an organic pigment. Specifically, the shape of the inorganic pigment and/or the organic pigment may be hollow or core-shell shaped. Furthermore, the organic pigment and/or inorganic pigment may be included alone or in a mixture of two or more types. As described above, the coating composition for a paper container further includes an inorganic pigment or an organic pigment, thereby improving the protective properties of the coating layer.

According to one embodiment of the present invention, the coating composition for a paper container may further include a metallic crosslinking agent. As described above, the coating composition for a paper container can improve the crosslinking speed by further including a metallic crosslinking agent.

According to one embodiment of the present invention, the metallic crosslinking agent may be an organic metal salt or an inorganic metal salt containing a divalent or higher metal cation including an alkaline earth metal or transition metal as a metal ion. Specifically, the divalent or higher metal cations are Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Mg ²⁺ , Pb ²⁺ , Cu ²⁺ , Cd ²⁺ , Co ²⁺ , Ni ²⁺ , Zn ²⁺ and Mn ²⁺ , etc., trivalent cations include Al ³⁺ , Fe ³⁺ , Sb ³⁺ , V ³⁺ , Co ³⁺ , and Au ³⁺ , and tetravalent metal cations include Sn ⁴⁺ , Ti ⁴⁺ , and Mn. ^4+, etc. may be used. More specifically, the metal ion of the metallic crosslinking agent may be one selected from the group consisting of Ca ²⁺ , Al ³⁺ , Fe ³⁺ , and combinations thereof. By selecting the metallic cross-linking agent from the above, the toxicity of the metallic cross-linking agent can be reduced, manufacturing costs can be reduced, and convenience of use can be improved.

According to one embodiment of the present invention, the metal cation may be used in the form of a neutral ion source. Specifically, the metal cation may be an inorganic calcium salt or an organic calcium salt. More specifically, in the case of calcium, the ion source in the neutral state is basically inorganic calcium salts such as calcium carbonate, calcium oxide, calcium hydroxide, calcium hydrogen phosphate, calcium nitrate, and calcium chloride, as well as calcium acetate, calcium lactate, and gluconic acid. A variety of organic calcium salts can be used, such as calcium, calcium citrate, and calcium propionate. More preferably, the calcium source is calcium carbonate, calcium oxide, calcium hydroxide, calcium chloride, calcium lactate, calcium citrate, calcium gluconate, monobasic calcium phosphate, dicalcium phosphate, tricalcium phosphate, 5'-ribonucleotide calcium carboxymethylcellulose calcium, It is preferable that it is calcium chitosan or the like.

According to one embodiment of the present invention, among the calcium ion sources, calcium hydroxide and calcium carbonate are basic and have extremely low solubility in water, but can be dissolved by the acidic component of carboxylic acid-modified PVA and are neutralized. It can perform the role of:

According to one embodiment of the present invention, inorganic calcium salts or organic calcium salts other than calcium hydroxide and calcium carbonate have the highest solubility in water at 20 ° C. in calcium chloride (75 g / 100 mL) and calcium lactate (8 g / 100 mL). 100mL) and calcium gluconate (3g/100mL), so it is desirable to add an appropriate amount relative to the acid value for optimal crosslinking.

According to one embodiment of the present invention, the content of the metallic crosslinking agent may be 0.01 equivalent or more and 5 equivalents or less based on the equivalent weight of the carboxylic acid group of the carboxylic acid-modified PVA. Specifically, the content of the metallic crosslinking agent may be 0.1 equivalent to 3 equivalents based on the equivalent weight of the carboxylic acid group of the carboxylic acid-modified PVA. More specifically, the content of the metallic crosslinking agent is preferably 0.5 equivalent or more and 1.5 equivalent or less based on the equivalent weight of the carboxylic acid group of the carboxylic acid-modified PVA. By adjusting the content of the metallic crosslinking agent within the above-mentioned range, the degree of crosslinking of the coating composition for a paper container is adjusted, and the mixture containing the acrylic resin is mixed in the first coating layer to prevent the moisture and oxygen barrier properties from being lowered. can do.

Figure 1 (a) is a schematic diagram of the reaction product of a coating composition for a paper container according to an exemplary embodiment of the present invention and a metallic crosslinking agent containing a divalent cation. Figure 1 (b) is a schematic diagram of the reaction product of a coating composition for a paper container according to an exemplary embodiment of the present invention and a metallic crosslinking agent containing a trivalent cation. Referring to FIG. 1, it can be seen that the crosslinking structure of the first coating layer is different depending on the type of metal cation.

One embodiment of the present invention includes a paper substrate (110); A first coating layer 130 provided on one side of the paper substrate 110 and being a dried product of the coating composition for a paper container; and a second coating layer 150, which is provided on one side of the first coating layer 130 opposite to the side on which the paper substrate 110 is provided, and is a dried product of a mixture containing an acrylic resin. Provides (100).

The paper container according to an exemplary embodiment of the present invention provides sealing properties, maximizes moisture barrier properties, and can simultaneously implement oxygen barrier properties.

Figure 2 is a schematic diagram of a cut surface of a paper container 100 according to an exemplary embodiment of the present invention. With reference to FIG. 2, a paper container 100 according to an exemplary embodiment of the present invention will be described in detail.

According to one embodiment of the present invention, the paper container 100 includes a paper substrate 110. As described above, the paper container 100 includes the paper substrate 110, thereby improving the dissociation effect during the recycling process.

According to one embodiment of the present invention, the paper substrate 110 may use pulp made of 100% long fiber (L-BKP). As described above, by using the paper substrate 110 as a pulp made of 100% long fiber (L-BKP), the paper container 100 can be used as a refrigerated packaging material and/or an oil-resistant packaging material.

According to one embodiment of the present invention, when the paper container 100 in which the paper substrate 110 is used is a refrigerated packaging material, the basis weight of the paper substrate 110 is 60 g/m ² or more and 100 g/m ² or less. You can. By adjusting the basis weight of the paper substrate 110 within the above-mentioned range, the characteristics required for the desired refrigerated packaging material can be implemented.

According to one embodiment of the present invention, when the paper container 100 in which the paper substrate 110 is used is an oil-resistant packaging material, the basis weight of the paper substrate 110 is 30 g/m ² or more and 50 g/m ² or less. You can. By adjusting the basis weight of the paper substrate 110 within the above-mentioned range, the properties required for the desired oil-resistant packaging material can be realized.

According to one embodiment of the present invention, the paper substrate 110 may use pulp containing long fibers (L-BKP) and short fibers (N-BKP). As described above, by using the paper substrate 110 as a pulp containing long fibers (L-BKP) and short fibers (N-BKP), flexibility and strength can be improved.

According to an exemplary embodiment of the present invention, pulp containing short fibers (N-BKP) in an amount of 5% by weight or more and 20% by weight or less can be used in the paper substrate 110. By adjusting the content of the short fibers (N-BKP) within the above-mentioned range, the tensile and tear strengths of the paper substrate 110 can be adjusted.

According to one embodiment of the present invention, a paper substrate containing pulp containing 5% by weight or more and 20% by weight or less of short fibers (N-BKP) can be used as a cup, tray, or paper. As described above, when the paper substrate 110 containing pulp containing 5% by weight or more and 20% by weight or less of the short fibers (N-BKP) is used as a cup, tray, or laminate, the cup, tray, or laminate The physical properties required can be realized.

According to one embodiment of the present invention, when the paper substrate 110 is used as a cup, tray, or paper, the basis weight of the paper substrate 110 may be 100 g/m ² or more and 300 g/m ² or less. By adjusting the basis weight of the paper substrate 110 within the above-mentioned range, the physical properties required for the cup, tray, and paper can be realized.

According to one embodiment of the present invention, the size of the paper substrate 110 measured according to KSM 7025 may be 20 seconds or more and 50 seconds or less. By adjusting the size measured in accordance with KSM 7025 of the paper substrate 110 within the above-mentioned range, excessive absorption of the coating composition is prevented from drying and breaking of the paper, and after drying, the coated surface It can prevent deterioration of performance due to delamination from the paper layer.

According to one embodiment of the present invention, the smoothness of the paper substrate 110 measured in accordance with KSM ISO 5636-5 may be 10 seconds or more and 120 seconds or less. By adjusting the smoothness of the paper substrate 110 within the above-mentioned range, it is possible to prevent performance degradation due to an increase in coating amount and a poor coating surface, and to achieve a desired coating layer thickness.

According to one embodiment of the present invention, the air permeability of the paper substrate 110 measured in accordance with KSM ISO 5636-1 may be 20 seconds or more. By adjusting the air permeability within the above-mentioned range, the gas permeability can be achieved at a low level.

According to one embodiment of the present invention, the paper substrate 110 is surface-treated with a treatment material containing one selected from the group consisting of starch, polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), and combinations thereof. It may be used after performing a post-calendering process.

According to one embodiment of the present invention, the surface treatment may be sizing or coating treatment.

According to one embodiment of the present invention, the paper substrate 110 has a product name of Billerudkorsnas, a basis weight of 70 g/m ² , 80 g/m ² , 90 g/m ² , and 100 g/m ² Prime White, 80 ^{Axello Glaze ​ ​ ​ ​ ​} ), 150 g/m ² , 160 g/m ² , 190 g/m ² , 210 g/m ² _, 230 g/m ² Wuxing Cup paper, 300 g/m ² KLB (international paper), 35 g /m ² , 50 g/m ² , 60 g/m ² , 70 g/m ² , 80 g/m ² It may be OJI Kraft Paper.

According to one embodiment of the present invention, the paper container 100 is provided on one surface of the paper substrate 110 and includes a first coating layer 130 that is a dried product of the coating composition for a paper container.

According to one embodiment of the present invention, the paper container 100 is provided on one side of the first coating layer 130, which is opposite to the side provided with the paper substrate 110, and is made of a mixture containing an acrylic resin. It includes a second coating layer 150 that is dried. As described above, the paper container 100 is provided on one side of the first coating layer 130 that is opposite to the side on which the paper substrate 110 is provided, and a second coating layer is a dried product of a mixture containing an acrylic resin. By including (150), sealing properties can be improved.

According to one embodiment of the present invention, the second coating layer 150 is a dried product of a mixture containing an acrylic resin. As described above, by using the dried product of a mixture containing an acrylic resin as the second coating layer 150, alkali dissociation and dispersibility are improved for recycling of paper packaging materials, and water resistance, oil resistance, heat resistance, and abrasion resistance are improved along with sealing properties. , impact resistance, light resistance, etc. can be additionally given.

According to one embodiment of the present invention, the acrylic resin is an acrylic acid copolymer and acrylic acid ester copolymerized with acrylic acid and alkylene such as ethylene and propylene. Copolymers (acrylic ester copolymers) and alkyl acrylate, alkyl methacrylate, ethyl hexylacrylate, etc. may be used singly or in copolymer form. Among the commercialized products, the acrylic resin includes Michem's prime 498345N (MP498345), Flex B1001, vaporbase 2160, vaporcoat 1300, Daeyang Polysol Co., Ltd.'s DC-9740, Dongin's PG-1000 series, and Snogen's OP-134. It can be applied. By selecting the acrylic resin from the above, water resistance and oil resistance can be ensured.

According to one embodiment of the present invention, the mixture containing the acrylic resin may include an acrylic resin, an emulsifier, ammonium persulfate, citric acid, water, and additional additives.

According to one embodiment of the present invention, the acrylic resin may be a polymerization of acrylic monomers.

According to one embodiment of the present invention, the acrylic monomer is methyl acrylate, ethyl acrylate, propyl acrylate, 2-hydroxyethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl It may be composed of methacrylate, ethyl methacrylate, hydroxyethyl methacrylate, butyl methacrylate, isobutyl methacrylate, styrene monomer, acrylic acid, methacrylic acid, and one or a combination of two or more thereof. Preferably, it may be a combination of methyl methacrylate, butyl methacrylate, and methacrylic acid.

According to one embodiment of the present invention, the weight average molecular weight of the acrylic resin is not limited, but may be 50,000 or more and 1,000,000 or less in consideration of water resistance, heat resistance, sealing properties, etc. Specifically, the weight average molecular weight of the acrylic resin is preferably 200,000 or more and 600,000 or less. By adjusting the weight average molecular weight of the acrylic resin within the above-mentioned range, sealing properties, mass productivity, water resistance, and heat resistance can be improved.

According to one embodiment of the present invention, the viscosity of the mixture containing the acrylic resin may be 5 cps or more and 800 cps or less. Specifically, the viscosity of the mixture containing the acrylic resin may be 50 cps or more and 300 cps or less. By adjusting the viscosity of the mixture containing the acrylic resin within the above-mentioned range, it can be easily applied to the roll-to-roll process.

According to one embodiment of the present invention, the solid content of the acrylic resin in the mixture containing the acrylic resin may be 30% by weight or more and 70% by weight or less. By adjusting the solid content of the acrylic resin within the above-mentioned range, water resistance can be improved and blocking phenomenon can be prevented during coating.

According to one embodiment of the present invention, the solid content of the first coating layer 130 may be 1 g/m ² or more and 20 g/m ² or less. By adjusting the solid content of the first coating layer 130 within the above-mentioned range, the oxygen and moisture barrier properties of the paper container 100 can be improved.

According to one embodiment of the present invention, the solid content of the second coating layer 150 may be 1 g/m ² or more and 10 g/m ² or less. By adjusting the solid content of the second coating layer 150 within the above-mentioned range, the oxygen and moisture barrier properties of the paper container 100 can be improved.

Figure 3 is a schematic diagram of a cut surface of a paper container 100 according to an exemplary embodiment of the present invention.

According to an exemplary embodiment of the present invention, as shown in FIG. 3, the first coating layer 130 may be 2 or more layers and 10 or less layers. Specifically, in the composition of the coating solution used to form a multilayer of 2 to 10 layers of the first coating layer 130, the type of metallic crosslinking agent, the equivalent weight of the metallic crosslinking agent, and the solid content concentration of the coating solution can be adjusted. As described above, by implementing the first coating layer 130 to be 2 or more layers and 10 or less layers, the occurrence of voids in the first coating layer 130 can be minimized and the surface smoothness can be improved to improve the air permeation blocking characteristics. Figure 4 is a schematic diagram of a cut surface of a paper container 100 according to an exemplary embodiment of the present invention.

According to one embodiment of the present invention, the second coating layer 150 is further provided on the other side of the paper substrate 110, which is the opposite side of the first coating layer 130, as shown in FIG. 4. You can. As described above, the second coating layer 150 is further provided on the other side of the paper substrate 110, which is opposite to the first side of the paper substrate 110, so that the paper container 100 Oxygen and moisture barrier properties can be improved.

According to one embodiment of the present invention, the first coating layer provision step (S130, not shown) in which the first coating layer 130 of the paper substrate 100 is provided and the first coating layer 130 of the paper substrate 110 It may include a second coating layer provision step (S150, not shown) in which the second coating layer 150 is further provided on the other side, which is opposite to the provided side. As described above, a first coating layer provision step (S130, not shown) in which the first coating layer 130 of the paper substrate 100 is provided and one side of the paper substrate 110 provided with the first coating layer 130 By including a second coating layer provision step (S150, not shown) in which the second coating layer 150 is further provided on the opposite side, moisture and oxygen barrier properties can be improved.

According to an exemplary embodiment of the present invention, the drying temperature of the first coating layer 130 in the first coating layer provision step (S130) may be 70°C or more and 140°C or less. By adjusting the drying temperature of the first coating layer 130 within the above-mentioned range, a crosslinking reaction can be performed and productivity can be improved.

According to one embodiment of the present invention, the drying time of the first coating layer 130 in the first coating layer provision step (S130, not shown) may be 30 seconds or more, 10 minutes or less, or 10 minutes or more. By adjusting the drying time of the first coating layer 130 within the above-mentioned range, a crosslinking reaction can be performed and productivity can be improved.

Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention may be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those skilled in the art.

Synthesis example (preparation of carboxylic acid modified PVA)

Synthesis Example 1

A reflux cooler, stirrer, thermometer, and inlet were prepared in a four-neck double jacket reaction vessel connected to a constant temperature circulator, and 900 g of water and 100 g of PVA (OCA, P-17) were added to prepare a PVA aqueous solution. The PVA aqueous solution was sufficiently stirred at a constant temperature of 90°C and stirring at 400 rpm to prepare a PVA aqueous solution with a solid content concentration of 10% by weight. To 1000 g of the PVA aqueous solution cooled to room temperature, 27.022 g of sodium persulfate as a radical initiator (equivalent to 50 mole parts of sodium persulfate for 100 mole parts of an acrylic acid derivative containing a carboxylic acid group to be described later) and sodium as a radical initiator reaction auxiliary. Add 11.811 g of sodium bisulfite (equivalent to 50 mole parts of sodium bisulfite for 100 mole parts of acrylic acid derivative containing a carboxylic acid group to be described later), raise the temperature of the constant temperature circulator to 75°C, dissolve, and stir for 10 minutes. Radicals were allowed to form. Afterwards, 8.179 g of acrylic acid as an acrylic acid derivative containing a carboxylic acid group (corresponding to 5 mole parts of an acrylic acid derivative containing a carboxylic acid group with respect to 100 mole parts of the PVA) was added and stirred. After reacting for 24 hours and cooling to room temperature, reprecipitation was performed by slowly adding dropwise to an ethanol solution 10 times the volume ratio of the reaction solution cooled to room temperature using a dropping funnel. The precipitated solid was obtained, washed again with an ethanol solution, and dried under vacuum for more than a day to prepare carboxylic acid-modified PVA solid in which an acrylic acid derivative containing a carboxylic acid group was polymerized.

Synthesis Example 2

In Synthesis Example 1, 27.022 g of sodium persulfate as a radical initiator (corresponding to 50 mole parts of sodium persulfate for 100 mole parts of an acrylic acid derivative containing a carboxylic acid group to be described later) and sodium bisulfite as a radical initiation reaction auxiliary. 11.811 g of acrylic acid (equivalent to 50 mole parts of sodium bisulfite per 100 mole parts of an acrylic acid derivative containing a carboxylic acid group to be described later) was added, and 16.358 g of acrylic acid as an acrylic acid derivative containing a carboxylic acid group (10 mole parts of acrylic acid derivative per 100 mole parts of PVA) was added. Carboxylic acid-modified PVA in which an acrylic acid derivative containing a carboxylic acid group was polymerized was prepared in the same manner as Synthesis Example 1 except that (equivalent to molar parts) was added and stirred.

Synthesis Example 3

In Synthesis Example 1, 27.022 g of sodium persulfate as a radical initiator (corresponding to 50 mole parts of sodium persulfate for 100 mole parts of an acrylic acid derivative containing a carboxylic acid group to be described later) and sodium bisulfite as a radical initiation reaction auxiliary. 11.811 g of acrylic acid (equivalent to 50 mole parts of sodium bisulfite per 100 mole parts of an acrylic acid derivative containing a carboxylic acid group to be described later) was added, and 24.536 g of acrylic acid as an acrylic acid derivative containing a carboxylic acid group (equivalent to 15 mole parts of acrylic acid derivative per 100 mole parts of PVA) was added. Carboxylic acid-modified PVA in which an acrylic acid derivative containing a carboxylic acid group was polymerized was prepared in the same manner as Synthesis Example 1 except that (equivalent to molar parts) was added and stirred.

Synthesis Example 4

In Synthesis Example 1, 27.022 g of sodium persulfate as a radical initiator (corresponding to 50 mole parts of sodium persulfate for 100 mole parts of an acrylic acid derivative containing a carboxylic acid group to be described later) and sodium bisulfite as a radical initiation reaction auxiliary. bisulfite) 11.811 g (equivalent to 50 mole parts of sodium bisulfite relative to 100 mole parts of an acrylic acid derivative containing a carboxylic acid group to be described later) was added, and 19.536 g of methacrylic acid as an acrylic acid derivative containing a carboxylic acid group (acrylic acid relative to 100 mole parts of PVA described above) was added. Carboxylic acid-modified PVA in which an acrylic acid derivative containing a carboxylic acid group was polymerized was prepared in the same manner as in Synthesis Example 1, except that 10 mole parts of derivative) was added and stirred.

Examples and Comparative Examples (Paper Container Manufacturing)

Example 1

A coating composition for paper containers was prepared by dissolving carboxylic acid-modified PVA, in which an acrylic acid derivative containing a carboxylic acid group of Synthesis Example 1 was polymerized, in water to a solid content of 5% by weight. Calcium hydroxide as a metallic cross-linking agent was added in an amount of 0.5 equivalent to the equivalent of the acrylic acid derivative containing the carboxylic acid group of the carboxylic acid-modified PVA in the coating composition for paper containers, and then stirred and mixed for 24 hours. The coating composition for paper containers mixed with the metallic crosslinking agent was filtered under reduced pressure using a 500 mesh nylon fabric filter to remove foreign substances. To the filtered coating composition for paper containers, 10 parts by weight of silicon dioxide as inorganic nanoparticles was added based on 100 parts by weight of solid content of the carboxylic acid-modified PVA, and dispersed using an ultrasonic disperser. The dispersed coating composition for paper containers was depressurized on a desiccator to proceed with the degassing process.

The coating composition for paper containers was coated on one side of a paper substrate (BILLERUDKORSNAS, base paper Axello Glaze X 80gsm) using a bar coater. The paper substrate 110 coated with the coating composition for a paper container was dried in an internal circulation dryer at 80° C. for 10 minutes, and after drying, the solid content was coated to 3 g/m ² to form the first coating layer 130.

A mixture containing an acrylic resin (Snogen, OP-134-T14) was coated on the first coating layer of the paper substrate 110 coated with the first coating layer 130 using a bar coater. Drying was carried out in an internal circulation dryer at 80°C for 10 minutes, and after drying, it was coated to have a solid content of 5 g/m ² to form a second coating layer 150 and prepare a paper container 100.

Example 2

A paper container 100 was manufactured in the same manner as in Example 1, except that calcium carbonate was used as the inorganic nanoparticle.

Example 3

A paper container 100 was manufactured in the same manner as in Example 1, except that aluminum acetoacetate was used as the metallic crosslinking agent.

Example 4

A paper container 100 was prepared in the same manner as in Example 1, except that aluminum acetoacetate was used as the metallic crosslinking agent and calcium carbonate was used as the inorganic nanoparticle. Manufactured.

Example 5

A paper container 100 was manufactured in the same manner as in Example 1, except that the carboxylic acid-modified PVA of Synthesis Example 2 was used in Example 1.

Example 6

A paper container 100 was prepared in the same manner as in Example 1, except that the carboxylic acid-modified PVA of Synthesis Example 2 was used in Example 1, and calcium carbonate was used as the inorganic nanoparticle. Manufactured.

Example 7

A paper container 100 was produced in the same manner as in Example 1, except that the carboxylic acid-modified PVA of Synthesis Example 2 was used in Example 1, and aluminum acetoacetate was used as a metallic crosslinker. Manufactured.

Example 8

In Example 1, the carboxylic acid-modified PVA of Synthesis Example 2 was used, aluminum acetoacetate was used as a metallic crosslinker, and calcium carbonate was used as the inorganic nanoparticle. A paper container 100 was manufactured in the same manner as in Example 1.

Example 9

A paper container 100 was manufactured in the same manner as in Example 1, except that the carboxylic acid-modified PVA of Synthesis Example 3 was used in Example 1.

Example 10

A paper container 100 was manufactured in the same manner as in Example 1, except that the carboxylic acid-modified PVA of Synthesis Example 3 was used in Example 1, and calcium carbonate was used as the inorganic nanoparticle. did.

Example 11

A paper container 100 was manufactured in the same manner as in Example 1, except that the carboxylic acid-modified PVA of Synthesis Example 3 was used in Example 1, and aluminum acetoacetate was used as a metallic crosslinker. did.

Example 12

In Example 1, the carboxylic acid-modified PVA of Synthesis Example 3 was used, aluminum acetoacetate was used as a metallic crosslinker, and calcium carbonate was used as an inorganic nanoparticle. A paper container 100 was manufactured in the same manner as in Example 1.

Example 13

A paper container 100 was manufactured in the same manner as in Example 1, except that the carboxylic acid-modified PVA of Synthesis Example 4 was used in Example 1.

Comparative Example 1

In Example 1, the first coating layer 130 was formed so that the solid content of the first coating layer 130 was 3 g/m ² , the second coating layer was not formed, and the metallic crosslinking agent A paper container was manufactured in the same manner as Example 1, except that inorganic nanoparticles were not used.

Comparative Example 2

A paper container 100 was manufactured in the same manner as in Example 1, except that the first coating layer 130 was not formed and the metallic cross-linking agent and inorganic nanoparticles were not used.

Comparative Example 3

The paper substrate 110 of Example 1 was coated with an aqueous solution (concentration: 10% by weight) of PVA (OCI, P-17), which is not a carboxylic acid-modified PVA in which an acrylic acid derivative containing a carboxylic acid group was polymerized, and dried. 1 The paper container 100 was prepared in the same manner as in Example 1, except that the first coating layer 130 was formed so that the solid content of the coating layer was 3 g/m ² and that no metallic crosslinking agent or inorganic nanoparticles were used. Manufactured.

Experiment example

Oxygen permeability, moisture permeability, oil resistance, dissociation, and heat sealing properties were measured according to the following experimental example.

Experimental Example 1 (Oxygen Permeability)

The oxygen transmittance rate (OTR) of the paper container 100 manufactured through the above examples and comparative examples was measured using an oxygen transmittance measuring device (OX-TRAN Model 2/21, Mocon) according to the international standard ASTM D. It was evaluated to fit -3985. The paper container 100 manufactured through the above examples and comparative examples was manufactured into specimens measuring 5 cm in width and height, and were subjected to conditions of relative humidity of 0%, temperature of 23°C, purity of supplied oxygen of 99.9%, and supply pressure of 1 atm. Measurements were made at 1-hour intervals for more than 18 hours.

Experimental Example 2 (Moisture Permeability (Water Permeability))

The water vapor transmission rate (WVTR) of the paper container 100 manufactured through the above examples and comparative examples was measured using a water permeability measuring device (PERMATRAN-W Model 3/33, Mocon) according to the international standard ASTM. It was evaluated according to F-1249. The paper container 100 manufactured through the above examples and comparative examples was manufactured into specimens measuring 5 cm in width and height, and measurements were made at 1-hour intervals for more than 12 hours under conditions of relative humidity of 90% and temperature of 37.8°C.

Experimental Example 3 (Oil Resistance)

The oil resistance of the paper container 100 manufactured through the above examples and comparative examples was evaluated in accordance with Table 1 below, which is the water resistance and oil resistance evaluation standard of the American Paper and Pulp Technology Association test method (TAPPI T559 CM-12). . The test solution was placed on the coated surface of the manufactured paper container to check the wetness of the paper base after the test method standard time had elapsed. The kit No. in case of no wettability is indicated in the results.

kit No. Castor Oil (g) Toluene (mL) n-heptane (mL) One 969.0 0 0 2 872.1 50 50 3 775.2 100 100 4 678.3 150 150 5 581.4 200 200 6 484.5 250 250 7 387.6 300 300 8 290.7 350 350 9 193.8 400 400 10 96.9 450 450 11 0 500 500 12 0 450 550

Experimental Example 4 (Dissociation)

The dissociation test to evaluate the recyclability of the paper containers manufactured through the above examples and comparative examples was conducted in accordance with the standard test standard EL606 for alkali dissociability and dispersibility of packaging materials.

Experimental Example 5 (Heat Sealing)

Paper bags for food packaging were manufactured using the paper containers of the above examples and comparative examples, and frozen foods (dumplings, pork cutlets, and fried foods) were packaged and heat sealed. Heat sealing was performed at 180°C for 2 seconds, and a 180-degree peeling test was performed on the sealed specimen using a Weed Lab WL2100C peel strength tester (Universal Testing Machine, UTM).

The above Experimental Examples 1 to 5 were evaluated and summarized in Table 2 below. In the table below, "General" refers to an aqueous solution of PVA (OCI, P-17) (concentration: 10% by weight) rather than carboxylic acid-modified PVA in which an acrylic acid derivative containing a carboxylic acid group is polymerized.

item Composition type and solid content of the first coating layer 130 Solid content of the second coating layer (150) Types of Crosslinking Agents Types of Inorganic Nanoparticles oxygen permeability
(cc/m ² day) moisture permeability
(g/m ² day) oil resistance
(kit) dissociative Heat sealability (N/mm) Example 1 Synthesis Example 1,3 g/m ² 5g/ ^m2 Calcium hydroxide silicon dioxide 6.89 49.79 Kit12 O 0.28 Example 2 Synthesis Example 1,3 g/m ² 5g/ ^m2 Calcium hydroxide Calcium carbonate 1.88 48.47 Kit12 O 0.28 Example 3 Synthesis Example 1,3 g/m ² 5g/ ^m2 Aluminum acetoacetate silicon dioxide 6.79 57.86 Kit12 O 0.28 Example 4 Synthesis Example 1,3 g/m ² 5g/ ^m2 Aluminum acetoacetate Calcium carbonate 4.41 60.34 Kit12 O 0.28 Example 5 Synthesis Example 2,3 g/m ² 5g/ ^m2 Calcium hydroxide silicon dioxide 192.37 169.06 Kit12 O 0.28 Example 6 Synthesis Example 2,3 g/m ² 5g/ ^m2 Calcium hydroxide Calcium carbonate 54.82 198.78 Kit12 O 0.28 Example 7 Synthesis Example 2,3 g/m ² 5g/ ^m2 Aluminum acetoacetate silicon dioxide 6.58 126.75 Kit12 O 0.28 Example 8 Synthesis Example 2,3 g/m ² 5g/ ^m2 Aluminum acetoacetate Calcium carbonate 5.66 117.80 Kit12 O 0.28 Example 9 Synthesis Example 3,3 g/m ² 5g/ ^m2 Calcium hydroxide silicon dioxide 5.90 147.29 Kit12 O 0.28 Example 10 Synthesis Example 3,3 g/m ² 5g/ ^m2 Calcium hydroxide Calcium carbonate 208.57 179.31 Kit12 O 0.28 Example 11 Synthesis Example 3,3 g/m ² 5g/ ^m2 Aluminum acetoacetate silicon dioxide 210.28 73.69 Kit12 O 0.28 Example 12 Synthesis Example 3,3 g/m ² 5g/ ^m2 Aluminum acetoacetate Calcium carbonate 4.37 68.52 Kit12 O 0.28 Example 13 Synthesis Example 4,3 g/m ² 5g/ ^m2 Calcium hydroxide silicon dioxide 77.46 156.37 Kit12 O 0.28 Comparative Example 1 Synthesis Example 1,3 g/m ² - - - 380.9 Fail Kit3~4 O 0.31 Comparative Example 2 - 5g/ ^m2 - - Fail Fail Kit12 O 0.28 Comparative Example 3 Normal,3 g/ ^m2 5g/ ^m2 - - 2382.7 2741.1
-Fail Kit7~8 O 0.29

Referring to Table 2 above, it was confirmed that Examples 1 to 13 all had kit 12 oil resistance, satisfied dissociation properties, and had heat sealability of 0.28 N/mm or more.

In contrast, Comparative Example 1 shows that when the second coating layer 150 is not formed and no metallic crosslinking agent and inorganic nanoparticles are added, oxygen permeability increases, moisture permeability increases to an immeasurable level, and oil resistance decreases. Confirmed.

Comparative Example 2 confirmed that when the first coating layer was not formed, the oxygen permeability and moisture permeability increased to an immeasurable degree.

Comparative Example 3 confirmed that when PVA was used instead of carboxylic acid-modified PVA in which an acrylic acid derivative containing a carboxylic acid group was polymerized, oxygen permeability and moisture permeability increased and oil resistance decreased.

Therefore, the coating composition for paper containers according to an embodiment of the present invention has excellent water resistance, oil resistance, and heat sealing properties, and is harmless to the human body, so it can be used as paper containers including food packaging. Furthermore, the coated packaging material has dissociation properties, enabling recycling of the paper base paper through repulping, and has environmentally friendly characteristics as a water-based coating solution, so it can contribute to the production of products that are more eco-friendly than the products used and to environmental protection. The coating liquid of the invention can be smoothly applied in general paper coating equipment, including roll-to-roll processes, without adding other processes, and can be freely used by changing the coating weight depending on the application.

Although the present invention has been described in terms of limited embodiments in the above, the present invention is not limited thereto, and the technical idea of the present invention and the patent claims described below will be understood by those skilled in the art in the technical field to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equality.

100: Paper container
110: Paper substrate
130: first coating layer
150: second coating layer
S130: First coating layer provision step
S150: Second coating layer provision step

Claims (15)

Contains carboxylic acid modified PVA, inorganic nanoparticles and solvents,
The carboxylic acid-modified PVA is a coating composition for a paper container, which is a reaction product of a mixture containing an aqueous PVA solution and an acrylic acid derivative containing a carboxylic acid group. In claim 1,
A coating composition for a paper container, wherein the carboxylic acid-modified PVA includes a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2):
[Formula 1]

[Formula 2]

R ₁ is hydrogen, a straight-chain or branched alkyl group having 1 to 20 carbon atoms, or an aromatic group having 1 to 20 carbon atoms, and the "*" indicates a connection point. In claim 1,
A coating composition for a paper container, wherein the content of the acrylic acid derivative containing the carboxylic acid group is 1 mole part or more and 50 mole parts or less with respect to 100 mole parts of the PVA. In claim 1,
The mixture further includes a radical initiator,
The radical initiator is a coating composition for a paper container, wherein the radical initiator is an azo-based radical initiator, a peroxide-based radical initiator, and a combination thereof. In claim 4,
A coating composition for a paper container, wherein the content of the radical initiator is 2 mole parts or more and 80 mole parts or less with respect to 100 mole parts of the acrylic acid derivative containing the carboxylic acid group. In claim 1,
A coating composition for a paper container, wherein the solid content of the carboxylic acid-modified PVA is 1% by weight or more and 20% by weight or less. In claim 1,
The coating composition for paper containers further includes an antifoaming agent,
A coating composition for a paper container, wherein the content of the antifoaming agent is 0.1 part by weight or more and 3 parts by weight or less based on 100 parts by weight of the coating composition for a paper container. In claim 6,
A coating composition for a paper container, wherein the content of the inorganic nanoparticles is 0.1 part by weight or more and 30 parts by weight or less based on 100 parts by weight of solid content of the carboxylic acid-modified PVA. In claim 1,
The coating composition for a paper container further includes a metallic crosslinking agent. In claim 9,
A coating composition for a paper container, wherein the content of the metallic crosslinking agent is 0.01 equivalent to 5 equivalents based on the equivalent weight of the carboxylic acid group of the carboxylic acid-modified PVA. paper substrate;
A first coating layer provided on one side of the paper substrate and being a dried product of the coating composition for a paper container of claim 1; and
A paper container comprising a second coating layer, which is provided on one side of the first coating layer opposite to the side on which the paper substrate is provided, and is a dried product of a mixture containing an acrylic resin. In claim 11,
A paper container wherein the solid content of the first coating layer is 1 g/m ² or more and 20 g/m ² or less. In claim 11,
A paper container wherein the solid content of the second coating layer is 1 g/m ² or more and 10 g/m ² or less. In claim 11,
A paper container wherein the first coating layer is 2 or more layers and 10 or less layers. In claim 11,
A paper container wherein the second coating layer is further provided on the other side of the paper substrate, which is opposite to the one side provided with the first coating layer.