KR100713329B1 - Water-based coating composition for high gloss paper coating and method for the same - Google Patents

Abstract

More particularly, the present invention relates to a resin-reinforced emulsion resin having a glass transition temperature of -30 to 0 ° C and a resin-reinforced emulsion having a glass transition temperature of 90 to 120 ° C Wherein the resin is mixed at a ratio of 1: 0.1 to 0.4 in terms of a solid content weight, and an alkali-soluble resin having a weight average molecular weight of 12,000 or less and a molecular weight distribution of 2.5 or less and a glass transition temperature of 90 to 120 占 폚, The water-based coating agent is uniformly coated on paper, dried, and then passed through a calender at a temperature of 70 to 90 DEG C under a constant pressure to obtain a paper product having high gloss, excellent adhesion and abrasion resistance And the like.

Aqueous coating agents, paper, calenders, resin-reinforced emulsion resins, alkali-soluble resins

Description

TECHNICAL FIELD [0001] The present invention relates to a water-based coating composition for high-gloss paper coating and a coating method using the same.

The present invention relates to a water-based coating composition for high-gloss paper coating and a coating method using the same. More particularly, the present invention relates to a resin-coated emulsion resin having a glass transition temperature of -30 to 0 ° C, And a resin-reinforced emulsion resin having a weight average molecular weight of 12,000 or less and a molecular weight distribution of 2.5 or less and a glass transition temperature of 90 to 120 占 폚 were mixed in an amount of 1: 0.1 to 0.4 based on the solid content weight, ) And the above mixed resin reinforced emulsion resin are mixed in a ratio of 1: 1 to 2: 1 on a solid basis weight, and the mixture is uniformly coated on paper, dried, and calendered at a temperature of 70 to 90 ° C under a constant pressure. And a method of obtaining a paper product having high gloss and excellent adhesion and abrasion resistance.

Currently, paper wrapping paper produced in Korea uses a method of applying a polyethylene film or the like on the printing surface or coating a resin such as polystyrene in an organic solvent in order to increase the gloss of the printing surface and protect the surface. However, the method of attaching the film is inconvenient because it is impossible to recycle the paper or it is very difficult to recycle or incinerate it after use, which is not preferable from the viewpoints of environmental protection and resource recycling, and the use thereof is gradually decreasing. In addition, the method of dissolving a polymer material in an organic solvent and coating it on paper is a preferred method because of its excellent physical properties and excellent workability. However, it is recognized as a main cause of air pollution due to organic substances emitted when organic solvents are used. The risk of fire is high.

One of the proposals for solving these drawbacks is to use a water-based coating agent prepared by using water as a solvent or a dispersion medium, unlike a coating agent based on an organic solvent, which is harmless to the human body and has no risk of fire or explosion Lt; / RTI >

Many attempts have been made to prepare aqueous coatings for obtaining such water-based high gloss paper. US Patent No. 4,317,849 discloses a polymer latex (A) having a glass transition temperature of 38 ° C or higher and a polymer latex having a glass transition temperature of 5 to 25 ° C The polymer latex (B) is mixed at a weight ratio of 1: 0.1 to 1 to prepare a coating material. The coating material is applied on paper and dried. The polymer latex is passed through a calender which is not lower than the glass transition temperature of the polymer latex (A) A method of obtaining a high gloss paper was proposed. However, the gloss of the paper obtained by the above method is significantly lower than that of a product based on an organic solvent generally used at present.

In addition, U.S. Patent No. 5,215,812 discloses a process for producing a polymer latex having a glass transition temperature of at least 80 ° C., applying the polymer latex on paper, drying the polymer latex, passing the polymer latex through a calender under a temperature lower than the glass transition temperature of the polymer latex, And a method of obtaining the data. However, since the polymer latex having a high glass transition temperature is passed through a calender at a temperature lower than the glass transition temperature, the polymeric material does not form a continuous phase and has a spherical particle shape as it is, Lt; / RTI > In addition, it has a disadvantage in that the gloss is much improved as compared with the previous method, but the gloss is not as good as that of a product based on an organic solvent.

In general, it is known that a method of increasing the solids content of an aqueous coating agent is effective for increasing the gloss of a paper obtained by an aqueous coating method. However, in order to utilize such a technique, it is necessary to solve the problem of viscosity increase due to an increase in solid content. That is, as the solid content of the water-based coating increases, the viscosity increases sharply, and the water-based coating agent having a high viscosity becomes very difficult to be coated on paper, so that it is practically useless. A viscosity suitable for applying an aqueous coating on paper is good with a drop rate of 10 to 15 seconds with a No. 4 viscous cup prepared according to ASTM D4212 and a waterborne coating having a faster or slower drop rate is too low in viscosity It is difficult to apply uniformly on paper.

As mentioned above, an aqueous coating material for obtaining a high-gloss paper should have a proper selection of a polymer material and a high solid content and at the same time have an appropriate viscosity range. However, a technology satisfying all of these conditions has not yet been disclosed It is true.

The present inventors have conducted studies to obtain a high gloss paper using a water-based coating agent. As a result, they have found that the use of a polymer material having properties different from those of conventional polymer latexes is excellent in gloss, adhesion, abrasion resistance, A water-based coating agent having a high viscosity and a suitable viscosity range has been developed, and the present invention has been completed on this basis.

Accordingly, an object of the present invention is to provide a water-based coating composition which can obtain a paper product excellent in gloss, adhesion, abrasion resistance and the like, which is superior to a high-gloss paper product obtained by a previously disclosed technique.

Another object of the present invention is to provide a method of coating a paper product using the composition.

In order to accomplish the above object, the present invention provides an aqueous coating composition for high gloss paper, comprising an alkali-soluble resin having a weight average molecular weight of 12,000 or less, a molecular weight distribution of 2.5 or less, a glass transition temperature of 90 to 120 ° C, A resin reinforced emulsion resin having a glass transition temperature of 90 to 120 DEG C and a resin reinforced emulsion resin having a glass transition temperature of 90 to 120 DEG C in a ratio of 1: 0.1 to 0.4 based on a solid weight weight of 1: 2. ≪ / RTI >

In order to accomplish the above object, the coating method of the present invention is characterized in that the aqueous coating agent is uniformly applied on paper, dried, and then passed through calenders at a temperature of 70 to 90 캜 under a constant pressure.

Hereinafter, the present invention will be described in detail.

The polymeric materials used in the aqueous coating agent according to the present invention have the following characteristics.

Alkali Soluble Resin is a polymeric substance that has a carboxyl group in its molecule and dissolves in an alkaline water containing a hydroxy functional group by neutralization reaction. When it is applied on paper Thereby enhancing the gloss. The alkali-soluble resin used in the present invention has a weight average molecular weight of 12,000 or less, preferably 10,000 or less, more preferably 8,000 or less, and a molecular weight distribution of 2.5 or less, preferably 2.3 or less, more preferably 2.1 or less. When the molecular weight exceeds 12,000, the viscosity of the water-based coating becomes higher than that of a conventional coating, which makes it difficult to coat the coating on paper. When the molecular weight distribution exceeds 2.5, even if the weight-average molecular weight is 12,000 or less There is a disadvantage that it is difficult to coat the composition on paper by increasing the viscosity of the aqueous coating agent.

In addition, the alkali-soluble resin used in the present invention has a glass transition temperature of 90 to 120 ° C. When the glass transition temperature is higher than 120 ° C, the coating film is brittle and deteriorates in adhesiveness and abrasion resistance. When the glass transition temperature is lower than 90 ° C, the application surface and the calender adhere to each other during the passage through the calender at a temperature of 70 to 90 ° C, and the gloss is not good.

The Resin Fortified Emulsion used in the present invention is a resin prepared by a method of emulsion polymerization which provides a polymerization site using the above-mentioned alkali-soluble resin as a surfactant, and includes styrene, acrylic acid, methacrylic acid, methyl Means homopolymers or copolymers of methacrylate, methyl acrylate, 2-ethylhexyl acryl lake, ethyl acrylate, butyl acrylate, butyl methacrylate and the like. Since the emulsion prepared by the general emulsion polymerization method uses a surfactant having a low molecular weight, the deterioration of the surfactant occurs over time after the formation of the coating film, so that the gloss and the adhesion are deteriorated.

The resin-reinforced emulsion resin used in the present invention is prepared by mixing a resin having a glass transition temperature of -30 to 0 占 폚 and a resin having a glass transition temperature of 90 to 120 占 폚 at a ratio of 1: 0.1 to 0.4 in terms of solid content When the ratio of the resin is more than 1: 0.4, when the aqueous coating agent is applied on paper and dried, the continuous phase can not be formed. Thus, the adhesion with paper decreases and the abrasion resistance deteriorates. When the ratio is less than 1: 0.1, there is a problem that the coating surface and the calender are stuck to each other during the process of passing the calender at a temperature of 70 to 90 캜, and the gloss is not good.

The water-based coating agent obtained from the results of the present invention is composed of 1: 1 to 2 by weight of the solid content ratio of the alkali-soluble resin and the resin-reinforced emulsion resin. If the weight ratio exceeds 1: 2, In the case of a weight ratio of less than 1: 1, when the water-based coating agent is applied on paper and dried, it can not form a continuous phase, and the adhesion with paper And the abrasion resistance is deteriorated.

As a method of applying the aqueous coating agent obtained as a result of the present invention on a printing surface of a paper, a bar coater, a knife coater, an air-knife coater, a roll coater, etc. Any method can be used as long as it can uniformly coat the water-based coating agent on the printing surface. As the drying method, natural drying, hot air drying and wind drying at room temperature can be used.

On the other hand, after the water-based coating on the printing surface is dried, it is passed through a calendar under a certain temperature and constant pressure to further improve the effect of gloss. The temperature is preferably 70 to 90 ° C. When the temperature is lower than 70 ° C, the improvement effect of gloss is not significant. When the temperature is higher than 90 ° C, the coated surface of the aqueous coating solution and the calender are stuck together, resulting in poor workability and poor gloss. In addition, a uniform pressure of at least 10 kgf / cm 2 is applied to spread the applied polymer materials evenly and to increase the smoothness. Under the pressure of 10 kgf / cm 2 or less, the polymeric materials can not be spread evenly, and the smoothness is lowered, and as a result, the effect of improving the gloss is not so small.

Although the aqueous coating material according to the present invention has a mixture of polymer materials having a low glass transition temperature, when the coating material is applied on a paper printing surface and dried and then passed through a calender under a temperature and pressure of 70 to 90 ° C, It is possible to find an unusual phenomenon that does not stick. Although such a cause has not yet been clarified yet, the following explanation can be made based on the facts observed through the present invention. That is, when passing through a calender having a temperature higher than the glass transition temperature of the polymer substance, the polymer substance becomes soft and adheres to the surface of the calender, but the resin reinforcement emulsion resin having a glass transition temperature of -30 to 0 캜 Is mixed with a resin-reinforced emulsion resin having a glass transition temperature of 90 to 120 DEG C and an alkali-soluble resin having a glass transition temperature of 90 to 120 DEG C so that a polymer substance having a high glass transition temperature is mixed with a polymer substance having a low glass transition temperature Called " Blocking & Therefore, a polymer material having a low glass transition temperature can form a continuous phase on a paper surface without being attached to a calender, and a polymer material having a high glass transition temperature is dispersed in the polymer material to increase the effect of gloss, It can be considered that adhesion and abrasion resistance are improved.

In the present invention, in order to further improve the abrasion resistance, the polyethylene wax emulsion or the paraffin wax emulsion alone or a mixture thereof is used in an amount of 0.5 to 4 phr, preferably 1 to 3 phr, more preferably 2 to 3 phr based on 100 parts by weight of the water- When it is more than 4 phr, the gloss may be lowered, and when it is less than 0.5 phr, abrasion resistance is not greatly improved. In addition, a small amount of a defoaming agent, an anionic emulsifier, an ionic crosslinking agent and the like may be added in order to improve the workability at the time of preparing the aqueous coating solution or on the paper surface.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited thereto.                     

The physical property measurement method used in this embodiment is as follows.

- Viscosity: Viscosity measured according to ASTM D 4212 standard. The time at which the aqueous coatings filled in cup No. 4 all escaped through the holes located in the lower part of the viscosity cup.

- Gloss: 60 DEG gloss was measured using a BYK-Gardner gloss meter manufactured to conform to the ASTM D 523 standard. The gloss of the paper itself and the gloss after application of the aqueous coating and after drying and the gloss after passing through the calender were all measured.

- Adhesion: After applying a water-based coating agent and drying it, the sample passed through the calender was made into 100 square grooves on the coated film surface using a cross-hatch cutter, and the adhesive force was measured by counting the number of the adhesive tape .

- Abrasion resistance: Abraser Tester manufactured by Sheen made to conform to ASTM D 4060 standard was rubbed 100 times with a woolen fabric and weighed.

- Solid content: A sample of a certain weight was placed in a vacuum oven at 90 ° C and -750 mmHg and dried for 3 hours, and the weight was measured to calculate the solid content by the following formula (1).

Solid content (%) = (sample weight after drying / sample weight before drying) x 100

Example 1

A 58 part of deionized water and a Soluryl-70 resin (weight average molecular weight: 6800, molecular weight distribution: 2.0, glass transition temperature: 105 DEG C) as an alkali water-soluble resin of Hanwha Petrochemical Co. ), And 9 parts of 28% ammonia water are slowly added dropwise thereto, followed by stirring at 80 ° C for 3 hours or more to prepare a 33% alkali water-soluble resin solution.

44 parts of Soluryl R-20 resin (glass transition temperature: -16 ° C, solid content: 50%), a resin-reinforced emulsion resin of Hanwha Petrochemical Co., Ltd., resin reinforcement of Hanwha Petrochemical Co., 11 parts of an emulsion resin, Soluryl R-90 resin (glass transition temperature: 98 ° C, solid content: 50%), and 45 parts of the 33% alkali water-soluble resin solution prepared above, and sufficiently stirred to mix well. To the mixture was added 1.5 phr of Aerosol OT-75 (Cytec) as an anionic emulsifier, 1 phr of Nopco NDW (Nopco) as a defoaming agent, 10 phr of a polyethylene wax emulsion of SC Johnson Polymer, % ZnO aqueous solution, and the mixture is stirred sufficiently. Deionized water was added to the viscosity cup No. 4 (Zhan Cup 405/4, manufactured by SHEEN Co.) manufactured by ASTM D 4212 standard so that the dropping rate was about 12 to 14 seconds to finally prepare an aqueous coating material having a solid content of 36% .

The above water-based coating agent was applied on an art paper of 360 g / m < 2 > on a dry basis in an amount of 10 g / m < 2 > using a roll coater and dried using wind at room temperature. After drying, the art paper coated with the aqueous coating agent was passed through a calendar made of stainless steel heated to a pressure of 100 kgf / cm 2 and a temperature of 85 ° C to complete the coating operation.

Example 2

The same procedure as in Example 1 was carried out except that the coating method of the aqueous coating composition was applied on an art paper of 360 g / m 2 on a dry basis using a bar coater in an amount of 10 g / m 2 on a dry basis and hot air dried at 60 ° C, The art paper coated with the coating agent was passed through a calendar made of stainless steel heated to a pressure of 100 kgf / cm < 2 > and a temperature of 75 DEG C to complete the coating operation.

Comparative Examples 1 and 2

Except that the paper coated with the aqueous coating agent was passed through calenders at 120 ° C and 60 ° C, respectively.

The physical properties of the paper products obtained from the results of Examples 1 and 2 and Comparative Examples 1 and 2 are summarized in Table 1 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Solid content (%) 36 36 36 36 Viscosity (sec) 12-14 12-14 12-14 12-14 Calender temperature (℃) 85 75 120 60 Adherence with calender No bonding No bonding Adhered No bonding Gloss after drying (60 °) 62 62 62 62 Gloss after passing through calender (60 °) 85 82 56 73 Adhesion (%) 100 99 99 100 Abrasion resistance (%) 89 88 88 90

As shown in Table 1, when the aqueous coating agent obtained in Examples 1 and 2 was used for coating, a paper product having excellent gloss and excellent adhesion and abrasion resistance was obtained. However, if the temperature of the calender is too low, the improvement of the gloss is not significant. If the temperature of the calender is too high, the water-based coating applied on the paper may adhere to the calender, It was found that the result was not good. For reference, the gloss of the art paper itself of 360 g / m 2 is about 30 in the 60 ° gloss system, and the gloss when coated based on the organic solvent is about 85 to 90 in the 60 ° gloss system.

Example 3

58 parts of deionized water and Soluryl-50 resin (weight average molecular weight: 4800, molecular weight distribution: 2.0, glass transition temperature: 98 占 폚) of an alkali water-soluble resin of Hanwha Petrochemicals were placed in a reactor equipped with a heat exchanger and temperature- ) 33 parts, and 9 parts of 28% ammonia water are slowly added dropwise, followed by stirring at 80 ° C for 3 hours or more to prepare a 33% alkali water-soluble resin solution.

39 parts of Soluryl R-20 resin (glass transition temperature: -16 ° C, solid content: 50%), resin-reinforced emulsion resin of Hanwha Petrochemical Co., Ltd., resin reinforcement of Hanwha Petrochemical Co., 9 parts of an emulsion resin, Soluryl R-90 resin (glass transition temperature: 98 ° C, solid content: 50%), and 52 parts of the 33% aqueous alkali solution prepared above, and stir thoroughly to mix well. 7.5 phr of a paraffin / polyethylene wax emulsion ME-62330 (30% solids) of Michelman Co., USA, 1.5 phr of ANION DO # 113 (South East Hwaseong) as anionic emulsifier, 1 phr of Nopco NDW (Nopco Corporation) 2 phr of 10% aqueous ZnO solution, etc. and stir well. Deionized water was added to the viscosity cup No. 4 (Zhan Cup 405/4, manufactured by SHEEN Co.) manufactured by ASTM D 4212 standard so that the dropping rate was about 12 to 14 seconds to finally prepare an aqueous coating agent having a solid content of 40% . The subsequent coating operation is the same as that in Embodiment 1.

Example 4

Except that Joncryl-678 resin (weight average molecular weight: 8500, molecular weight distribution: 2.0, glass transition temperature: 90 占 폚) of SC Johnson Polymer Co., Ltd. was used instead of Soluryl-70 resin of Hanwha Petrochemical Co. This is the same as Example 1. The solids content of the final aqueous coating was 33%.

Example 5

Except that Soluryl-120 resin (weight average molecular weight: 11500, molecular weight distribution: 2.0, glass transition temperature: 110 占 폚) of Hanwha Petrochemical Co., Ltd. was used instead of Soluryl-70 resin of Hanwha Chemical Company The same as in Example 1. The solids content of the final aqueous coating was 30%.

Comparative Example 3

Water-soluble resin so that the glass transition temperature was 105 ° C, the weight average molecular weight was 15,000, and the molecular weight distribution was 2.0 in a 7: 3 ratio of styrene to acrylic acid in a continuous reactor (Continuous Stirred Tank Reactor) And all of them were the same as those of Example 1, except that the alkali-water-soluble resin thus synthesized was used. However, deionized water was added to the viscosity of the prepared aqueous coating solution to 12 to 14 seconds in the above-mentioned viscosity cup, and the final solid content of the water-based coating agent obtained from this was 26%.

Comparative Example 4

A continuous water-jacketed continuous reactor (Continuous Stirred Tank Reactor) was charged with an aqueous alkali-soluble resin such that the ratio of styrene and acrylic acid was 7: 3, the glass transition temperature was 105 ° C, the weight average molecular weight was 10,000, And all of them were the same as those of Example 1 except that the alkali-soluble resin thus synthesized was used. However, deionized water was added to the viscosity of the prepared aqueous coating agent to 12 to 14 seconds in the above-mentioned viscosity cup, and the final solid content of the aqueous coating agent obtained from this was 27%.

The physical properties of paper products obtained from the results of Examples 3 to 5 and Comparative Examples 3 to 4 are summarized in Table 2 below.

Example 3 Example 4 Example 5 Comparative Example 3 Comparative Example 4 Solid content (%) 40 33 30 26 27 Viscosity (sec) 12-14 12-14 12-14 12-14 12-14 Calender temperature (℃) 85 85 85 85 85 Adherence with calender No bonding No bonding No bonding No bonding No bonding Gloss after drying (60 °) 68 61 58 50 51 Gloss after passing through calender (60 °) 91 81 78 70 73 Adhesion (%) 98 99 99 100 99 Abrasion resistance (%) 91 89 90 90 91

As can be seen from Table 2, various alkali-soluble resins having a weight-average molecular weight of less than 12,000, a molecular weight distribution of less than 2.5, and a glass transition temperature of from 90 to 120 캜 were used, Abrasion resistance. Especially, it was found that the higher the solid content, the more marked the improvement of the gloss. However, when the weight average molecular weight of the alkali-soluble resin is high or the molecular weight distribution is wide, the amount of the deionized water to be additionally added is so low that the solid content is lowered so as to have an appropriate viscosity range, It was found that it was not significantly superior.

Example 6                     

Joncryl-74 (glass transition temperature: -16 占 폚, solid content: 48.5%) and Joncryl-89 (trade name, manufactured by SC Johnson Polymer Co., Ltd.) were used instead of Soluryl R- Glass transition temperature: 95 캜, solids content: 48%) was used. The solids content of the final aqueous coating was 32%.

Comparative Example 5

Except that the resin-reinforced emulsion resin Soluryl R-20 and Soluryl R-90 were used in amounts of 32 parts and 23 parts, respectively.

Comparative Example 6

Except that the amounts of Soluryl R-20 and Soluryl R-90, which are resin reinforced emulsion resins, are used in 52 parts and 3 parts, respectively.

The physical properties of the paper products obtained from the results of Example 6 and Comparative Examples 5 to 6 are summarized in Table 3 below.

Example 6 Comparative Example 5 Comparative Example 6 Solid content (%) 32 36 36 Viscosity (sec) 12-14 12-14 12-14 Calender temperature (℃) 75 85 75 Adherence with calender No bonding No bonding Adhered Gloss after drying (60 °) 61 64 62 Gloss after passing through calender (60 °) 81 83 65 Adhesion (%) 100 92 100 Abrasion resistance (%) 89 78 90

As can be seen from the above Table 3, even when the kinds of the resin-reinforced emulsion resins having a glass transition temperature of -30 to 0 占 폚 and 90 to 120 占 폚 are changed, paper products excellent in gloss, adhesion and abrasion resistance can be obtained Respectively. However, when the content of the resin-reinforced emulsion resin having a high glass transition temperature was increased (Comparative Example 5), the gloss was excellent but the adhesion and abrasion resistance were poor. On the contrary, when the content of the resin- ) Adhesion and abrasion resistance were good, but it was found that gloss was not good.

Comparative Example 7

Except that the amounts of 33% Soluryl-70 alkaline aqueous solution, Soluryl R-20 and Soluryl R-90 were used in 32 parts, 53 parts and 15 parts, respectively. The solids content of the final aqueous coating was 37%.

Comparative Example 8

Except that the amounts of 33% Soluryl-70 alkaline aqueous solution, Soluryl R-20 and Soluryl R-90 were used in 73 parts, 22 parts, and 5 parts, respectively. The solids content of the final aqueous coating was 32%.

Comparative Examples 9 and 10

Except that the amount of polyethylene wax emulsion (Jonwax-26 from S. C. Johnson Polymer, solid content 26%) was used in an amount of 1 phr and 20 phr, respectively.

The physical properties of the paper products obtained from the results of Comparative Examples 7 to 10 are summarized in Table 4 below.                     

Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Solid content (%) 37 32 36 36 Viscosity (sec) 12-14 12-14 12-14 12-14 Calender temperature (℃) 75 85 85 85 Adherence with calender Adhered No bonding No bonding No bonding Gloss after drying (60 °) 60 63 62 62 Gloss after passing through calender (60 °) 61 82 82 75 Adhesion (%) 100 88 99 100 Abrasion resistance (%) 90 82 90 96

As shown in Table 4, when the content of the resin-reinforced emulsion is high, the content of the resin having a low glass transition temperature is increased to cause the water-based coating agent applied on the paper to adhere to the calender. And the results are not good. On the other hand, when the content of the alkali-soluble resin was high, the gloss was excellent, but the resin having a low glass transition temperature on the paper surface did not form a continuous phase sufficiently, so that the adhesion and abrasion resistance were not good.

On the other hand, when the wax emulsion was slightly used, the effect of improving the abrasion resistance was not large. In order to further improve the abrasion resistance, it was found that increasing the amount of the wax emulsion was effective but the gloss was lowered.

As can be seen from the above Examples and Comparative Examples, by using the polymeric materials different from the conventional art such as the alkali-soluble resin and the resin-reinforced emulsion resin, an aqueous coating agent having superior gloss, excellent adhesion and abrasion resistance than the conventional aqueous coating technology And if it is applied to a paper wrapper company that actually attaches a film on paper or dissolves a polymer material in an organic solvent, it is very desirable from the viewpoint of environmental protection and recycling, and it can reduce the risk to human body and fire. Also, the viscosity range is similar to that of conventional materials used in industry, so it is very applicable to related industries.

Claims (4)

An alkali-soluble resin having a weight average molecular weight of 12,000 or less, a molecular weight distribution of 2.5 or less and a glass transition temperature of 90 to 120 캜, a resin reinforcing emulsion resin having a glass transition temperature of -30 to 0 캜, Wherein the resin-reinforced emulsion resin obtained by mixing the resin-reinforced emulsion resin at 120 ° C in a ratio of 1: 0.1 to 0.4 based on the solid weight is mixed in a ratio of 1: 1 to 2 based on the solid weight basis. . The composition of claim 1, wherein the aqueous coating composition further comprises 0.5 to 4 phr of polyethylene wax emulsion or paraffin wax emulsion, alone or in combination, based on 100 parts by weight of the aqueous coating. The resin-reinforced emulsion resin according to claim 1, wherein the resin-reinforced emulsion resin is selected from the group consisting of styrene, acrylic acid, methacrylic acid, methyl methacrylate, methyl acrylate, 2-ethylhexyl acryl lake, ethyl acrylate, butyl acrylate or butyl methacrylate ≪ / RTI > or a copolymer thereof. A coating method comprising uniformly applying an aqueous coating agent according to any one of claims 1 to 3 on paper and drying it, then passing the calender at a temperature of from 70 to 90 캜 under a constant pressure.