KR20020010018A - Water-based coating composition for high gloss paper coating and method for the same - Google Patents

Abstract

PURPOSE: A composition of aqueous coating agent for coating paper and a coating method using it are provided, which is characterized by having excellent luster, abrasion resistance and adhesive property. CONSTITUTION: The aqueous coating agent is obtained by: mixing resin reinforcement emulsion resin having -30-0deg.C of glass transition temperature and resin reinforcement emulsion resin having 90-120deg.C of glass transition temperature in a ratio of 1:0.1-0.4 based on a weight of solids; and mixing alkali water soluble resin having under 12,000 of weight average molecular weight, under 2.5 of molecular weight distribution and 90-120deg.C of glass transition temperature with the mixed resin reinforcement emulsion resin in a ratio of 1:1-2 based on a weight of solids. The coating method is as follows: coating paper with the aqueous coating agent uniformly; drying; and then passing through 70-90deg.C of a calender under a uniform pressure.

Description

Water-based coating composition for high gloss paper coating and method for the same}

The present invention relates to an aqueous coating agent composition for coating a high gloss paper and a coating method using the same, and more particularly, a resin reinforced emulsion resin and a glass transition temperature having a glass transition temperature of -30 to 0 ° C. The resin-reinforced emulsion resin of 120 ° C. is mixed at 1: 0.1 to 0.4 based on the weight of solids, the weight average molecular weight is 12,000 or less, the molecular weight distribution is 2.5 or less, and the glass transition temperature is 90-120 ° C. (Alkali Soluble Resin) ) And the mixed resin-reinforced emulsion resin of the above 1: 1 to 2 based on the weight of the solid content and uniformly coated on paper and dried, and then calendered at a temperature of 70 to 90 ° C. under a certain pressure. The present invention relates to a method for obtaining a paper product having high gloss and excellent adhesion and wear resistance.

Currently, paper packaging paper produced in Korea uses a method of attaching a film such as polyethylene on a printing surface or dissolving a resin such as polystyrene in an organic solvent in order to increase the glossiness of the printing surface and to protect the surface thereof. However, since the method of attaching the film is impossible or very difficult to recycle the paper, landfilling or incineration after use is not preferable in terms of environmental protection and resource recycling, and thus the use thereof is gradually decreasing. In addition, the method of dissolving a polymer in an organic solvent and coating it on paper is a preferred method because of its excellent physical properties and excellent workability, but it is recognized as a major cause of air pollution due to the organic substances emitted when using organic solvents. Because of this, there is a high risk of fire.

One of the proposed methods to solve these drawbacks is the use of water-based coatings prepared using water as a solvent or dispersion medium. Unlike coatings based on organic solvents, they are harmless to humans and have no risk of fire or explosion. Have

Many attempts have been made to prepare an aqueous coating agent for obtaining a high gloss paper based on such water. In US Pat. No. 4,317,849, polymer latex (A) having a glass transition temperature of 38 ° C. or higher and a glass transition temperature of 5-25 ° C. The polymer latex (B) is mixed at a ratio of 1: 0.1 to 1 by weight of solid content to prepare a coating agent, coated on paper, dried, and passed through a calender under a temperature not lower than the glass transition temperature of the polymer latex (A). A method of obtaining a high gloss paper was presented. However, there is a disadvantage that the gloss of paper obtained by the above method is significantly lower than that of products based on organic solvents currently commonly used.

In addition, US Pat. No. 5,215,812 prepares a polymer latex having a glass transition temperature of at least 80 ° C. or more, applies it to paper, and then dries it, passes a high gloss paper by passing it through a calender at a temperature lower than the glass transition temperature of the polymer latex. The method to obtain is presented. However, since the polymer latex having a high glass transition temperature is passed through a calendar having a lower temperature than the glass transition temperature, the polymer material does not form a continuous phase on the paper and has a spherical particle shape. Have In addition, the gloss is much improved compared to the previous method, but has a disadvantage that the gloss is not as good as that of the product based on the organic solvent.

In general, in order to increase the gloss of paper obtained through the aqueous coating method, it is known that the method of increasing the solid content of the aqueous coating agent is effective. However, in order to utilize these techniques, the problem of viscosity increase due to the increase of solid content must be solved. In other words, when the solid content of the water-based coating agent is increased, the viscosity is sharply increased, and since the water-based high-coating agent is very difficult to apply on the paper, the practical availability almost disappears. Viscosity suitable for coating the water-based coating agent on paper is 4 viscosity cups made according to ASTM D4212. The viscosity of the water-based coating agent is 10-15 seconds. Or high, it is difficult to apply uniformly on paper.

As mentioned above, the water-based coating agent for obtaining a high gloss paper should be selected from a suitable polymer material and a high solids and at the same time have an appropriate viscosity range, but the technology that satisfies all of these conditions has not yet been disclosed. It is true.

Therefore, the present inventors conducted a study for obtaining a high gloss paper by using an aqueous coating agent, using a polymeric material having a different characteristic from the conventional polymer latex, excellent gloss, adhesion, wear resistance, etc., the solid content An aqueous coating agent having a high and suitable viscosity range has been developed, and the present invention has been completed based on this.

Accordingly, an object of the present invention is to provide an aqueous coating agent composition which can obtain a paper product excellent in gloss, adhesion, abrasion resistance and the like than a high-gloss paper product that can be obtained by a conventionally disclosed technology.

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

The aqueous coating agent composition for coating a high gloss paper of the present invention for achieving the above object has a weight average molecular weight of 12,000 or less, a molecular weight distribution of 2.5 or less, an alkali-soluble resin having a glass transition temperature of 90 to 120 ° C., and a glass transition temperature. The resin-reinforced emulsion resin in which the resin-reinforced emulsion resin of -30 to 0 ° C. and the resin-reinforced emulsion resin of glass transition temperature of 90 to 120 ° C. is 1: 0.1 to 0.4 based on the weight of solids, and is 1: 1 to 1 based on the weight of solids. It consists of a mixture of two ratios.

The coating method of the present invention for achieving the above another object is made by passing the calender (calendar) at a temperature of 70 ~ 90 ℃ under a constant pressure by applying the aqueous coating agent uniformly on paper and dried.

Hereinafter, the present invention will be described in detail.

Polymeric materials used in the aqueous coating agent according to the present invention has the following characteristics.

Alkali Soluble Resin is a polymer material that has a carboxyl group (carboxylic functional group) in its molecule and is dissolved by neutralization in alkaline water in which a hydroxyl group (Hydroxy functional group) is present. It will increase the gloss. The alkali water-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, and more preferably 2.1 or less. If the molecular weight exceeds 12,000, the viscosity of the water-based coating agent is higher than that used in general coating, which makes it difficult to apply on paper.In the case where the molecular weight distribution exceeds 2.5, even if the weight average molecular weight is less than 12,000 There is a disadvantage in that it is difficult to apply on paper by increasing the viscosity of the water-based coating agent.

In addition, the alkali water-soluble resin used in the present invention has a feature that the glass transition temperature is 90 ~ 120 ℃, if the glass transition temperature exceeds 120 ℃ has the disadvantage that the coating film is brittle (brittle) and adhesion and wear resistance is inferior In addition, when the glass transition temperature is less than 90 ℃, the coating surface and the calendar adheres in the process of passing through the calendar of 70 ~ 90 ℃ temperature and gloss is not good.

Resin fortified emulsion resin used in the present invention is a resin prepared by the method of emulsion polymerization that provides a polymerization place using the above-mentioned alkali water-soluble resin as a surfactant, styrene, acrylic acid, methacrylic acid, methyl Homopolymers or copolymers such as methacrylate, methyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate, butyl acrylate, and butyl methacrylate. Since emulsions prepared using a general emulsion polymerization method use a low molecular weight surfactant, the phenomena of the surfactants deteriorate as time passes after the coating film is formed.

Meanwhile, the resin-reinforced emulsion resin used in the present invention is mixed with a resin having a glass transition temperature of -30 to 0 ° C. and a resin having a glass transition temperature of 90 to 120 ° C. in a ratio of 1: 0.1 to 0.4 based on the weight of solids. When the ratio of the resin exceeds 1: 0.4, when the aqueous coating agent is applied on the paper and dried, it does not form a continuous phase, and thus the adhesive strength with the paper decreases and the wear resistance deteriorates. 1: When less than 0.1, the problem of adhesion between the coated surface and the calendar in the process of passing through the calendar of 70 ~ 90 ℃ temperature and 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 ratio of the solid content of the alkali water-soluble resin and the resin-reinforced emulsion resin, but when the weight ratio exceeds 1: 2, it passes through a calendar at 70 to 90 ° C. In the process of applying, there is a problem in that the coated surface and the calendar adhere to each other and the gloss is not good.In the case where the weight ratio is less than 1: 1, when the water-based coating agent is applied on the paper and dried, it does not form a continuous phase and thus adheres to the paper. There is a disadvantage that the wear resistance and deterioration.

As a method of applying the water-based coating agent obtained as a result of the present invention on the printed surface of the paper, a bar coater, a knife coater, an air-knife coater, a roll coater, etc. Any method can be applied as long as the water-based coating agent can be uniformly applied on the printing surface. As a drying method, natural drying, hot air drying, drying using air at room temperature, and the like are possible.

On the other hand, after the water-based coating on the printing surface is dried through a calender (Calendar) at a constant temperature and a constant pressure to further improve the effect of the gloss, the temperature is suitable 70 ~ 90 ℃. If the temperature is less than 70 ℃, the effect of improving the glossiness is not great, and if it exceeds 90 ℃, the coated surface and the calendar of the aqueous coating liquid adhere to each other, not only poor workability but also poor gloss. In addition, a uniform pressure of at least 10 kgf / cm 2 is applied to evenly spread the applied polymer materials and increase smoothness. Under the pressure of 10kgf / ㎠ or less, the polymer material is not evenly spread evenly and the smoothness is lowered as a result, the effect of improving the glossiness is not large.

Although the water-based coating agent according to the present invention is mixed with polymer materials having a low glass transition temperature, when the calender and the coated surface are applied to the paper printing surface and then passed through the calender under a temperature and pressure of 70 to 90 ° C. Unusual unusual phenomenon can be found. This cause has not been clearly identified yet, but the following explanation can be made based on the facts observed through the present invention. In other words, when passing through a calender having a temperature higher than the glass transition temperature of the polymer, the polymer becomes soft and adheres to the surface of the calender. However, the glass transition temperature used in the present invention is -30 to 0 ° C. Is mixed with resin-reinforced emulsion resin with glass transition temperature of 90-120 ℃ and alkali water-soluble resin with glass transition temperature of 90-120 ℃, so that high glass transition polymers are low. It can be considered to have a so-called blocking action that prevents it from sticking to it. Therefore, polymer materials with a low glass transition temperature can form a continuous phase on paper without sticking to the calendar, and polymer materials with a high glass transition temperature form a dispersed phase to enhance the effect of gloss and It can be considered that adhesion and wear resistance are improved.

Meanwhile, in the present invention, in order to further improve wear resistance, polyethylene wax emulsion or paraffin wax emulsion alone or a mixture thereof is 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-soluble coating agent. In the case of using more than 4 phr, the gloss may be reduced, and when used in less than 0.5 phr, wear resistance is not greatly improved. In addition, a small amount of an antifoaming agent, an anionic emulsifier, an ionic crosslinking agent, etc. may be added in order to improve workability during the preparation of the aqueous coating solution or the coating on the paper surface, and the addition method and the amount of use may follow a general method.

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 the present Example is as follows.

Viscosity: The time taken for the aqueous coating agent filled in Viscosity Cup No. 4 made to conform to the ASTM D 4212 standard escapes through the hole located at the bottom of the Viscosity Cup.

Gloss: 60 ° gloss was measured using a BYK-Gardner glossmeter made to conform to ASTM D 523 standard. Both the gloss of the paper itself, the gloss after application of the aqueous coating agent and drying, and the gloss after passing through the calender were measured.

-Adhesive force: After applying and drying the water-based coating agent, the sample passed through the calendar was made with 100 square grooves on the surface of the coating film using a cross-hatch cutter, and the adhesive force was measured by counting the number of falling and sticking with adhesive tape. .

Abrasion resistance: Sheen Abraser Tester manufactured to meet the standard of ASTM D 4060 was used and the weight was measured after rubbing 100 times with a cloth of wool.

-Solid content: After a certain weight of the sample in a vacuum oven of 90 ℃, -750mmHg and dried for 3 hours, the weight was measured to calculate the solid content by the following equation (1).

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

Example 1

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

Soluryl R-20 resin (glass transition temperature: -16 ℃, solid content: 50%) 44 parts, Hanwha Chemical Co., Ltd. 11 parts of an emulsion resin Soluryl R-90 resin (glass transition temperature: 98 ° C., solid content: 50%) were added thereto, and 45 parts of the 33% alkali water-soluble resin solution prepared above were stirred well to be thoroughly mixed. Here is 8.5 phr of Jonwax-26 (26% solids) polyethylene wax emulsion from SC Johnson Polymer, 1.5 phr of Aerosol OT-75 (Cytec) as an anionic emulsifier, Nopco NDW (Sannov Co., Ltd.) 1 phr, 10 Add 2 phr of ZnO aqueous solution and stir thoroughly. Deionized water was added to Viscosity Cup No. 4 (Zhan Cup 405/4 manufactured by SHEEN) according to ASTM D 4212 standard so that the drop speed was about 12 to 14 seconds, thereby preparing an aqueous coating agent having a solid content of 36%. .

The water-based coating agent was applied to the amount of 10 g / ㎡ on a dry basis on a 360 g / ㎡ art paper using a roll coater and dried using air at room temperature. After drying, the coating was completed by passing an art paper coated with an aqueous coating agent through a calender of a stainless steel heated at a pressure of 100 kgf / cm 2 and a temperature of 85 ° C.

Example 2

The same method as in Example 1, but the coating method of the water-based coating agent using a bar coater (Bar Coater) on an art paper of 360g / ㎡ on the basis of drying 10g / ㎡ on a dry basis and hot air dried at 60 ℃, after drying the aqueous coating agent The applied art paper was passed through a stainless steel calender (Calendar) heated to a pressure of 100 kgf / ㎠ and a temperature of 75 ℃ was only different to complete the coating operation.

Comparative Examples 1 and 2

It is the same as Example 1 except the paper coated with the aqueous coating agent is passed through a calendar 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 (seconds) 12-14 12-14 12-14 12-14 Calendar temperature (℃) 85 75 120 60 Adhesion with calendar No adhesion No adhesion Bonded No adhesion Gloss after drying (60 °) 62 62 62 62 Glossy after passing through the calendar (60 °) 85 82 56 73 Adhesion (%) 100 99 99 100 Wear resistance (%) 89 88 88 90

As a result of coating using the water-based coating agent obtained in Examples 1 and 2 in Table 1, it was possible to obtain a paper product having excellent gloss and excellent adhesion and wear resistance. However, if the temperature of the calendar is too low, the effect of gloss improvement was not so great. If the temperature of the calendar was too high, the water-based coating agent applied on the paper would stick to the calendar, resulting in poor workability. It was found that the result was bad. For reference, the glossiness of the 360 g / m 2 art paper itself is about 30 degrees with 60 ° gloss, and the gloss when coated with an organic solvent is about 85 to 90 degrees with 60 ° gloss.

Example 3

58 parts of deionized water and Soluryl-50 resin, an alkali-soluble resin of Hanwha Chemical Co., Ltd. (weight average molecular weight: 4800, molecular weight distribution: 2.0, glass transition temperature: 98 ℃) ) 33 parts were added and 9 parts of 28% ammonia water was slowly added dropwise, followed by stirring at 80 ° C. for at least 3 hours to prepare a 33% alkali water-soluble resin solution.

Soluryl R-20 resin (glass transition temperature: -16 ℃, solid content: 50%), 39 parts, Hanwha Chemical Co., Ltd. 9 parts of emulsion resin Soluryl R-90 resin (glass transition temperature: 98 ° C., solid content: 50%) and 52 parts of the 33% alkali water-soluble resin solution prepared above are added and stirred well. 7.5 phr of ME-62330 (30% solids) of paraffin / polyethylene wax emulsion of Michelman of USA, 1.5 phr of ANION DO # 113 (Namsung) for anionic emulsifier, 1 phr of Nopco NDW (Sannov Co., Ltd.) as an antifoaming agent. Add 2 phr of 10% aqueous ZnO solution and stir sufficiently. Deionized water was added to Viscosity Cup No. 4 (Zhan Cup 405/4 manufactured by SHEEN) according to ASTM D 4212 standard so that the drop speed was about 12 to 14 seconds, and finally an aqueous coating agent having a solid content of 40% was prepared. . After the coating operation is the same as in Example 1.

Example 4

Except for using Hanwha Petrochemical Co., Ltd.'s Joncryl-678 resin (weight average molecular weight: 8500, molecular weight distribution: 2.0, glass transition temperature: 90 ℃) instead of Soluryl-70 resin of Hanwha Chemical Same as Example 1. Solid content of the final water-based coating agent was 33%.

Example 5

Except for using Hanwha Chemical's Soluryl-120 resin (weight average molecular weight: 11500, molecular weight distribution: 2.0, glass transition temperature: 110 ℃) instead of Soluryl-70 resin of Hanwha Chemical Same as Example 1. Solid content of the final water-based coating agent was 30%.

Comparative Example 3

In the continuous stirred tank reactor equipped with a jacket, temperature-controlled styrene and acrylic acid were used in the ratio of 7: 3, so that the alkali water-soluble resin was used 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. It was prepared, and everything is the same as in Example 1 except that the alkali water-soluble resin synthesized in this way. However, more deionized water was added than Example 1 so that the viscosity of the prepared aqueous coating agent was about 12 to 14 seconds using the aforementioned viscosity cup, and the final solid content of the aqueous coating agent obtained therefrom was 26%.

Comparative Example 4

In the continuous stirred tank reactor, which is equipped with a jacket, temperature-controlled styrene and acrylic acid are used at a ratio of 7: 3, so that the alkali water-soluble resin is used so that the glass transition temperature is 105 ° C, the weight average molecular weight is 10,000, and the molecular weight distribution is 3.0. It was prepared, and everything is the same as in Example 1 except that the alkali-soluble resin synthesized in this way. However, more deionized water was added than Example 1 so that the viscosity of the prepared aqueous coating agent was about 12 to 14 seconds using the aforementioned viscosity cup, and the final solid content of the aqueous coating agent obtained therefrom was 27%.

The physical properties of the 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 (seconds) 12-14 12-14 12-14 12-14 12-14 Calendar temperature (℃) 85 85 85 85 85 Adhesion with calendar No adhesion No adhesion No adhesion No adhesion No adhesion Gloss after drying (60 °) 68 61 58 50 51 Glossy after passing through the calendar (60 °) 91 81 78 70 73 Adhesion (%) 98 99 99 100 99 Wear resistance (%) 91 89 90 90 91

As can be seen from Table 2, as a result of using 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 90 to 120 ° C., all have excellent gloss, adhesion, Abrasion resistance was shown. In particular, the higher the solid content, the better the improvement of gloss. However, when the weight-average molecular weight of the alkali-soluble resin is high or when the molecular weight distribution is large, the amount of additional deionized water added is too high to have an appropriate viscosity range, resulting in a low solid content and thus glossiness. It was found that not very good.

Example 6

Joncryl-74 (glass transition temperature: -16 ℃, solid content: 48.5%) of SC Johnson Polymer, instead of Soluryl R-20 and Soluryl R-90 resin of Hanwha Chemical Co., Ltd. Glass transition temperature: 95 ℃, solid content: 48%) was the same as in Example 2 except that. Solid content of the final water-based coating agent was 32%.

Comparative Example 5

All of them are the same as in Example 1 except that 32 parts and 23 parts of Soluryl R-20 and Soluryl R-90, which are resin-reinforced emulsion resins, are used.

Comparative Example 6

Except for using 52 parts and 3 parts of Soluryl R-20 and Soluryl R-90, which are resin-reinforced emulsion resins, all are the same as in Example 2.

Table 3 shows the physical properties of the paper products obtained from the results of Example 6 and Comparative Examples 5 to 6.

Example 6 Comparative Example 5 Comparative Example 6 Solid content (%) 32 36 36 Viscosity (seconds) 12-14 12-14 12-14 Calendar temperature (℃) 75 85 75 Adhesion with calendar No adhesion No adhesion Bonded Gloss after drying (60 °) 61 64 62 Glossy after passing through the calendar (60 °) 81 83 65 Adhesion (%) 100 92 100 Wear resistance (%) 89 78 90

As can be seen from Table 3, even if the type of resin-reinforced emulsion resin having a glass transition temperature of -30 ~ 0 ℃ and 90 ~ 120 ℃ can be obtained a paper product excellent in gloss, adhesion and wear resistance It was confirmed. However, when the content of resin-reinforced emulsion resin with high glass transition temperature was increased (Comparative Example 5), the gloss was excellent but adhesion and wear resistance was not good. ) It was found that adhesion and abrasion resistance were good but gloss was poor.

Comparative Example 7

Everything is the same as Example 2 except using 32 parts, 53 parts, and 15 parts of 33% Soluryl-70 aqueous alkali solution, Soluryl R-20 and Soluryl R-90 respectively. Solid content of the final water-based coating agent was 37%.

Comparative Example 8

Everything is the same as in Example 1 except that 73 parts, 22 parts and 5 parts of 33% Soluryl-70 aqueous alkali solution, Soluryl R-20 and Soluryl R-90 are used. Solid content of the final water-based coating agent was 32%.

Comparative Examples 9 and 10

Everything is the same as in Example 1 except that 1 phr, 20 phr of polyethylene wax emulsion (Jonwax-26, 26% solids) of S. C. Johnson Polymer was used.

Table 4 shows the physical properties of the paper products obtained from the results of Comparative Examples 7 to 10.

Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Solid content (%) 37 32 36 36 Viscosity (seconds) 12-14 12-14 12-14 12-14 Calendar temperature (℃) 75 85 85 85 Adhesion with calendar Bonded No adhesion No adhesion No adhesion Gloss after drying (60 °) 60 63 62 62 Glossy after passing through the calendar (60 °) 61 82 82 75 Adhesion (%) 100 88 99 100 Wear resistance (%) 90 82 90 96

As shown in Table 4, in the case where the content of the resin-reinforced emulsion was high, the content of the resin having a low glass transition temperature was increased to cause the water-based coating agent applied on the paper to adhere to the calendar. In terms of bad results were found. On the contrary, when the content of alkali water-soluble resin was high, the gloss was excellent, but the resin having low glass transition temperature on the paper surface did not sufficiently form a continuous phase, and the adhesion and wear resistance were poor.

On the other hand, when the wax emulsion was used a little, the effect of improving abrasion resistance was not great. In order to further improve the wear 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, using a polymer material different from the conventional techniques such as alkali water-soluble resins and resin-reinforced emulsion resins to prepare an aqueous coating agent having excellent gloss, excellent adhesion and wear resistance than the conventional aqueous coating technology If it is applied to a paper packaging company that actually attaches a film on paper or coats a polymer by dissolving it in an organic solvent, it is highly desirable in terms of environmental protection and recycling, and may reduce the risk of human and fire. In addition, the viscosity range is set to a similar degree to the materials used in the existing industry, so it will be highly applicable to the relevant industry.

Claims (4)

Alkali-soluble resin having a weight average molecular weight of 12,000 or less, molecular weight distribution of 2.5 or less, glass transition temperature of 90 to 120 ° C, resin-reinforced emulsion resin of glass transition temperature of -30 to 0 ° C, and glass transition temperature of 90 to A water-based coating composition for coating a high gloss paper, characterized in that the resin-reinforced emulsion resin mixed with a resin-reinforced emulsion resin of 120 ° C. in a weight ratio of 1: 0.1 to 0.4 is mixed at a ratio of 1: 1 to 2 by weight of a solid content. . The composition of claim 1, wherein the water-based coating composition further comprises 0.5 to 4 phr based on 100 parts by weight of the water-soluble coating agent alone or mixed with polyethylene wax emulsion or paraffin wax emulsion. According to claim 1, wherein the resin-reinforced emulsion resin alone of styrene, acrylic acid, methacrylic acid, methyl methacrylate, methyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate, butyl acrylate or butyl methacrylate A composition characterized in that it is a polymer or a copolymer thereof. The coating method according to any one of claims 1 to 3, wherein the aqueous coating agent according to any one of claims 1 to 3 is uniformly coated on paper and dried, and then passed through a calendar having a temperature of 70 to 90 ° C. under a predetermined pressure.