KR100855092B1 - method of manufacturing Waterborn polyester resin, Waterborn plastic coating paint and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a water-soluble plastic coating material applied to automotive interior coating and a method for manufacturing the same, wherein the water-soluble plastic coating material includes a polyester polyol having a carboxyl group at both ends and a hydroxyl value of 50 to 120 mgKOH / g, and 1,500 to 15 to 28% by weight of a water-soluble polyester resin of a three-dimensional network having a weight average molecular weight of 4,000. 15 to 45 weight percent polyurethane dispersion resin and 8 to 16 weight percent curing agent. In addition, 11 to 20% by weight titanium dioxide, 0.5 to 2% by weight of additives and excess water. The paint having the composition described above may be coated on plastic to form a soft coating film.

Description

Method of manufacturing Waterborn polyester resin, Waterborn plastic coating paint and method of manufacturing the same

The present invention relates to a method for producing a water-soluble polyester resin, a water-soluble plastic coating material and a method for manufacturing the same, and a method for producing a water-soluble plastic coating material, a method for producing a water-soluble polyester resin coated on a plastic crash pad in a car, including the same A method for producing a plastic coating paint and a water-soluble plastic coating paint.

In general, the polyester resin is two-component, excellent in adhesion to the base material, flexibility of the coating film and light resistance, and has a good soft feel. For this reason, water-soluble polyester resins are used as one of the main raw materials for plastic paints. That is, the water-soluble polyester resin is used as a raw material of the plastic coating due to the excellent flexibility and soft feeling of the coating film.

In addition, since the plastic substrate has a relatively low light resistance, discoloration easily occurs when exposed to sunlight for a long time in the summer, and even if the plastic substrate is in a flexible state, even if the film is cured, the plastic substrate may be easily damaged by the impact. It is the reason why the water-soluble polyester which has is used for the said coating material.

Generally, the water-soluble polyester resins used in the market can be divided into organic solvent-free type and solvent-free type. In relation to environmental issues, raw materials for paints using solvent-free water-soluble polyesters are being developed. The characteristics of the developed water-soluble polyester coating film are as follows. First, flexibility (flexibility of the coating film) is given to the coating film formed. Secondly, it gives an excellent soft feeling (giving a natural leather feel to soften the coating). Third, impart excellent light resistance and wear resistance of the coating film. Fourthly, it is possible to develop an eco-friendly paint of a solvent-free type.

In the prior art, hydroxyl group-containing polyesters of water dispersions (prepolymers produced by condensation of linear, branched, cyclic aliphatic or aromatic multifunctional carboxylic acids and aliphatic linear or branched multifunctional alcohols) are reacted with a multifunctional isocyanate. A water dispersion binder for a coating material having a soft texture to be produced is described.

The water-dispersed binder is excellent in wear resistance and hardness, but lacks a soft feeling and light resistance, and thus it is difficult to introduce the entire amount into the plastic interior material. In addition, the water-dispersion binder of the prior art is reacted with a polyester polyol, dimethylolpropionic acid (DMPA) and isocyanate under N-methylpyrrolidone (NMP) solvent and neutralized with a neutralizing agent. It is then synthesized through the process of water dispersion.

In this case, the bifunctional amine is added to increase the molecular weight at the end of the reaction. At this time, an organic solvent (NMP) is inevitably used to offset the increase in viscosity caused by the increase in molecular weight, thereby preventing environmental problems and damage to worker's health. Can cause.

Accordingly, an object of the present invention for solving the above problems is to solve problems such as soft feeling and light resistance, which are problems of Polyurethane Dispersion resin, and at the same time increase the molecular weight in the production of paint containing polyurethane dispersion An object of the present invention is to provide a method for producing a water-soluble polyester resin in which use of an organic solvent inevitably used is excluded.

In addition, another object of the present invention is to provide a water-soluble plastic coating paint containing a water-soluble polyester resin having the above characteristics.

In addition, another object of the present invention to provide a method for producing a water-soluble plastic coating paint containing a water-soluble polyester resin having the above-described characteristics.

In the method for preparing a water-soluble polyester resin according to an embodiment of the present invention to achieve the above object, a divalent acid and an alcohol are added to a polyester polyol having a hydroxyl value of 50 to 120 mgKOH / g while having carboxyl groups at both ends. Condensation reaction. Neutralizing the first reactant obtained by the condensation reaction and having an acid value of 30 to 40 using an amine compound. And water dispersing the second reactant formed by the neutralization using water. As a result, a water-soluble polyester resin can be produced.

Water-soluble plastic coating material according to an embodiment of the present invention to achieve the above-mentioned other object is a polyester resin water-soluble paint for plastic coating is a polyester polyol having a hydroxyl value of 50 to 120 mgKOH / g while having a carboxyl group at both ends It includes, 15 to 28% by weight of a water-soluble polyester resin of a three-dimensional network having a weight average molecular weight of 1,500 to 4,000. 15 to 45 weight percent polyurethane dispersion resin and 8 to 16 weight percent curing agent. 11 to 20 weight percent titanium titrant, 0.5 to 2 weight percent additive and excess water.

As an example, the carboxyl group-containing polyester polyol may include 30 to 40% of the carboxyl group, and may have a molecular weight of 1000 to 3000.

In addition, according to the manufacturing method of the water-soluble paint for plastic coating according to an embodiment of the present invention for achieving the above another object, first having a carboxyl group at both ends, the hydroxyl value is 50 to 120 mgKOH / g polyester A water-soluble polyester resin having a three-dimensional network structure in which an ester chain is added to a polyol and having a weight average molecular weight of 1,500 to 4,000 is prepared. Thereafter, 15 to 28% by weight of the water-soluble polyester resin, 15 to 45% by weight of polyurethane dispersion resin, 8 to 16% by weight of curing agent, 11 to 20% by weight of titanium thioxide, 0.5 to 2% by weight of an additive and extra Mix the water. As a result, a water-soluble resin for plastic coating is produced.

According to one embodiment, the polyester polyol is 1,4-butylene glycol, 2,3-butylene glycol, 1,3-butylene glycol, 1,6-hexanediol, neopentyl glycol, 2-methyl- At least one difunctional alcohol selected from the group consisting of 1,3-pentanediol, 2-methyl-2,4-pentanediol and methylpropanediol and trifunctional trimetholol propane alcohols in an equivalent ratio of 1: 0.1 to 0.4 It can be formed by condensation reaction of mixed alcohols and divalent acids. At this time, the diacid may include alicyclic diacid 50 to 100% and aliphatic diacid 0 to 50% by weight.

As another example, the polyester polyol is 55 to 67 parts by weight of 2-methyl-2,4-pentanediol, 8 to 15 parts by weight of 1,6-hexanediol, and 8 to 16 of 2-methyl-1,3-pentanediol. It may be formed by condensation reaction of parts by weight, 4 to 9 parts by weight of trimethylolpropane, 30 to 50 parts by weight of adipic acid, and 95 to 130 parts by weight of hexahydrophthalic anhydride.

The water-soluble polyester resin is a condensation reaction by adding a dihydric acid and an alcohol to the carboxyl group-containing polyester polyol, and obtained by the condensation reaction, neutralizing the first reactant having an acid value of 30 to 40 using an amine compound It may be formed by sequentially performing the step, and the step of dispersing the second reactant formed by the neutralization reaction by adding water.

Hereinafter, a method for preparing a water-soluble polyester resin, a water-soluble plastic coating paint containing a water-soluble polyester resin and a method for producing the same according to preferred embodiments of the present invention will be described in detail, but the present invention is not limited to the following examples. It may be implemented in other forms without. In addition, the weight percentage and weight part may be used interchangeably and the embodiments introduced herein are provided to make the disclosure more complete and to fully convey the spirit and features of the present invention to those skilled in the art.

Water soluble polyester resin and preparation thereof

As described above, the water-soluble polyester resin of the present invention may be applied to a coating material for automobile plastic interior materials to impart a soft feeling to the interior materials and at the same time exclude the use of volatile solvents to minimize environmental pollution.

In order to manufacture the water-soluble polyester resin, first, a polyester polyol, which is a main component of the water-soluble polyester, must be prepared. The polyester polyol may be prepared by polymerizing an alcohol with an acid in the presence of a catalyst. Specifically, the polyester polyol may be formed by condensation reaction of a dihydric acid with an alcohol in which a bifunctional alcohol and a trifunctional alcohol having a primary linear structure are mixed in an equivalent ratio of 1: 0.1 to 0.4. As one example, the water-soluble polyester polyol is preferably formed using 65 to 75 parts by weight of alcohol, 45 to 55 parts by weight of acid.

Examples of the alcohol used in the preparation of the polyester polyol include 1,4-butylene glycol, 2,3-butylene glycol, 1,3-butylene glycol, 1,6-hexanediol, neopentyl glycol, 2- And bifunctional alcohols such as methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol and methylpropanediol and trimetholpropane which is a trifunctional alcohol. These can be used individually or in mixture of 2 or more.

The 1,4-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,6-hexanediol, methyl propanediol, 2-methyl-1,3-pentanediol, 2- When a water-soluble polyester resin comprising a polyester polyol prepared by applying a bifunctional alcohol having a primary linear structure containing methyl-2,4-pentanediol and diethylene glycol is applied to a plastic top coat, Soft feeling and flexibility can be promoted.

As an example, when the water-soluble polyester resin composition prepared when the difunctional alcohol used at this time is smaller than the above-mentioned equivalent ratio is applied to the plastic coating material, the softness and flexibility are poor, and when the water-soluble prepared water is greater than the equivalent ratio When the polyester resin composition is applied to a plastic top coat, the softness and workability are good, but the wear resistance and light resistance are poor. Therefore, it is preferable to use the bifunctional alcohol of a primary linear structure in the said range.

The trifunctional alcohol trimetholol propane serves to enhance the wear resistance of the coating film formed when the water-soluble polyester resin including the prepared polyester polyol is applied to the plastic top coat. In this case, when the trihydric alcohol used is smaller than the equivalent ratio described above, when the water-soluble polyester resin composition prepared is applied to a plastic top coat, softness and processability are good, but wear resistance is poor. On the other hand, when the amount of use is greater than the equivalent ratio, when the water-soluble polyester resin composition prepared is applied to a plastic top coat, wear resistance is good but softness and processability are poor. Therefore, it is preferable to use trifunctional trimetholol propane in the said range.

 Examples of the divalent acid include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, maleic anhydride, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, itaconic acid, and the like. Can be. Alicyclic aliphatic acid in the acid may contain 50 to 100% of the total divalent acid equivalent. In addition, at least one aliphatic acid selected from the group consisting of sebacic acid, adipic acid, itaconic acid, and azelaic acid may include 0 to 50% of the total divalent acid equivalent. That is, the diacid may include 50 to 100% of alicyclic diacid and 0 to 50% by weight of aliphatic diacid.

As one example, the polyester polyol is 55 to 67 parts by weight of 2-methyl-2,4-pentanediol, 8 to 15 parts by weight of 1,6-hexanediol, 8 to 16 of 2-methyl-1,3-pentanediol It can be formed by condensation reaction of 4 parts by weight, 4 to 9 parts by weight of trimethylolpropane, 30 to 50 parts by weight of adipic acid, and 95 to 130 parts by weight of hexahydrophthalic anhydride.

The polyester polyol is preferably formed to have an acid value of about 30 to 40 by a condensation reaction of an acid and an alcohol, and the reaction for forming the polyester polyol may be carried out according to conventional reaction conditions, and may be performed at about 200 ° C. or higher. can do.

As a result, the polyester polyol formed by the condensation reaction has a hydroxyl value of 50 to 120 mgKOH / g, and has a molecular weight of 1,000 to 3,000 while having a carboxyl group of 30 to 40% at both ends.

When the content of the carboxyl group contained in the polyester polyol is less than 30%, there is a lack of carboxyl group, so that it is difficult to receive water in the neutralization process of the amine for preparing the water-soluble polyester resin, and the content of the carboxyl group exceeds 40% In this case, the amount of amine required for neutralization is increased, which may cause problems of shelf life and yellowing of the prepared resin. Thus, the polyester polyol contains 30 to 40% of carboxyl groups, preferably 32 to 38% of carboxyl groups.

In addition, when the hydroxyl value of the carboxyl group-containing polyester polyol is less than 75, the soft segment is insufficient, the wear resistance, hardness is excellent, but the soft texture is reduced, and when the hydroxyl value exceeds about 120, the soft segment (Soft Segment) increases the soft texture is excellent, but wear resistance, hardness is poor. Thus, the polyester polyol has a hydroxyl value of 75 to 120 mgKOH / g, preferably has a hydroxyl value of 80 to 110 mgKOH / g.

Subsequently, a condensation reaction is carried out by adding a divalent acid and a difunctional alcohol to a polyester polyol having a carboxyl group at both ends and having a hydroxyl value of 50 to 120 mgKOH / g. As an example, the condensation reaction may be performed using 45 to 55 parts by weight of divalent acid and 65 to 75 parts by weight of difunctional alcohol in 100 parts by weight of the polyester polyol.

The bifunctional alcohol is used to solve the problem of flexibility caused by low molecular weight of the carboxyl group-containing polyester polyol through increasing the molecular weight. In addition, the divalent acid is added in an amount equivalent to the difunctional alcohol participating in the reaction in consideration of the attenuation of the carboxyl group contained in the polyester polyol, and the trimellitic having a carboxyl group at the terminal of the aromatic structure with the divalent acid. Anhydrides can be used.

As a result, irregular ester chains are added to the polyester polyols. In addition, the hydroxyl group (OH) group remaining unreacted in the polyester polyol may then react with the curing agent of the low temperature curing type.

For example, examples of the difunctional alcohol include ethylene glycol, propylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, 1,3-butylene glycol, 1,6-hexanediol, neopentyl glycol , 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, diethylene glycol, methyl propanediol, trimetholpropane, ethylene oxide added bisphenol A, propylene oxide added bisphenol A, and the like. Can be. These can be used individually or in mixture.

Examples of the divalent acid include phthalic anhydride, tetrahydrophthalic anhydride, hexahydro phthalic anhydride, trimellitic anhydride, maleic anhydride, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, and itaconic acid. Can be mentioned. These can be used individually or in mixture.

Subsequently, the condensation reaction is neutralized by adding an amine compound to the first reactant when the acid value of the first reactant to be formed is 30 to 40. At this time, it is preferable to add an amine compound so as to neutralize the acid value of the first reactant sufficiently. It is preferable to use 1-5 weight part of said amine compounds in the total resin compounding quantity.

Examples of the amine compound used as the neutralizing agent include triethylamine, ammonia water, hexamine, dimethylethanol amine ethylenediamine, and the like.

Subsequently, the second reactant formed by the neutralization reaction using the amine compound is water dispersed using water (deionized water). Preferably, the aqueous dispersion proceeds with stirring while slowly adding the second reactant and the water at a ratio of 1: 0.2 to 0.5.

As a result, a water-soluble polyester having a stereoscopic network having a hydroxyl value of 50 to 120 mgKOH / g and a weight average molecular weight in the range of 1,500 to 4,000 is formed. The water-soluble polyester resin may include a polyester polyol having a hydroxyl value of 50 to 120 mgKOH / g while having a carboxyl group at both ends.

When the molecular weight of the polyester-based resin obtained by the method exceeds 4,000, use of an organic solvent such as NMP is inevitable for dilution, and when the molecular weight is less than 1,500, a coating film having reduced wear resistance and hardness is formed.

Water Soluble Plastic Coating Paint And Manufacturing Method Thereof

The water-soluble plastic coating material of the present invention is a paint for coating automotive plastic interior materials, water-soluble polyester resins that can impart a soft feeling to the automotive interior materials and eliminate the use of volatile solvents, polyurethane dispersion resins, curing agents, Titanium dioxide, additives, excess water.

The water-soluble polyester resin includes a polyester polyol having a hydroxyl value of 50 to 120 mgKOH / g having a carboxyl group at both ends, and is designed to have a stereoscopic network having a weight average molecular weight of 1,500 to 4,000.

Specifically, the water-soluble polyester resin is primarily added to the acid and alcohol at the time of synthesis of the carboxyl group-containing polyester polyol to prepare a polyester polyol that satisfies the basic properties, and then secondly added after the polyfunctional acid and alcohol It is important to design so as to have the weight average molecular weight mentioned above, having a polymer skeleton of a stereoscopic network structure. By doing so, the molecular weight of the water-soluble polyester resin can be adjusted appropriately to be an environmentally friendly resin of a solvent-free type.

Here, the manufacturing method of the water-soluble polyester resin and a detailed description thereof are omitted in order to avoid duplication because it has been described in detail above.

Subsequently, 15 to 28% by weight of water-soluble polyester resin having the above characteristics, 15 to 45% by weight of polyurethane dispersion resin, 8 to 16% by weight of curing agent, 11 to 20% by weight of titanium dioxide, and 0.5 to 2 additives A water soluble plastic coating paint comprising a weight percent and excess water is prepared.

When the content of the water-soluble polyester resin contained in the water-soluble plastic coating paint is less than 15% by weight, the softness of the formed coating film is reduced, and when the content of the water-soluble polyester resin exceeds 28% by weight There arises a problem that the wear resistance of the coating film is lowered. Therefore, the water-soluble polyester resin is contained 15 to 28% by weight, preferably 18 to 25% by weight in the coating paint.

If the content of the polyurethane dispersion resin is less than 15% by weight, the soft texture falls, and if the content exceeds 45% by weight, wear resistance and scratch resistance are deteriorated. Therefore, the polyurethane dispersion resin is included in the coating material 15 to 45% by weight, preferably 25 to 40% by weight.

BYK Corporation WT2102 etc. are mentioned as an example of the said hardening | curing agent. When the content of the curing agent is less than 8% by weight, there is a problem in that solvent resistance and wear resistance are lowered because it is not completely cured, and when it exceeds 16% by weight, it is thickened during paint manufacturing and chemical resistance and water resistance when unreacted curing agent remains. Falls. Therefore, the curing agent is included in the coating paint 8 to 16% by weight, preferably 9 to 13% by weight.

The titanium dioxide is a sieving pigment. When the content of the titanium dioxide is less than 11% by weight, hiding power, gloss falls, and when it exceeds 20% by weight, it takes a long time to disperse the water, the paint viscosity rises and the overall paint properties decrease. Therefore, the titanium dioxide is included in the coating paint 11 to 20% by weight, preferably 9 to 16% by weight.

The additives include cryostabilizers, antifoams, and wet dispersants. The additive includes 0.5 to 2% by weight. The amount and type of the additives included in the paint may be used by those skilled in the art because the additives are used to further improve the physical properties of the water-soluble plastic coating paint. Therefore, the amount and composition of the additive used in the present invention are not specifically limited.

In addition, the excess water applied to the paint is used as a solvent for dissolving the viscosity and viscosity of the plastic coating paint of the present invention. The amount of water used does not specifically limit the amount of use and composition because the amount of use of the worker may vary.

In order to prepare the above-mentioned water-soluble plastic coating paint, first, it has a carboxyl group at both ends, has a three-dimensional network structure in which the ester chain is added to a polyester polyol having a hydroxyl value of 50 to 120 mgKOH / g, the weight average molecular weight is The water-soluble polyester resin which is 1,500-4,000 is prepared. The manufacturing method of the water-soluble polyester resin and a detailed description thereof are omitted in order to avoid duplication because they have been described in detail above.

Then, 15 to 28% by weight of the prepared water-soluble polyester resin, 15 to 45% by weight of the polyurethane dispersion resin, 8 to 16% by weight of the curing agent, 11 to 20% by weight of titanium dioxide, 0.5 to 2% by weight of the additive and Water mixes. As a result, a water-soluble plastic coating paint is produced.

Hereinafter, the present invention will be described in detail through specific examples. However, it is a matter of course that the present invention is not limited only to the following examples.

Synthesis Example

1) Preparation of carboxyl group-containing polyester polyol

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer and condenser and a temperature raising device was attached. 62.4 g of methyl propanediol, 11.8 g of 1,6-hexanediol, 13.5 g of 1,4-butylene glycol, 6.2 g of trimethylolpropane, 40 g of adipic acid, and 110.39 g of hexahydrophthalic anhydride were added thereto. Slowly stirring while injecting nitrogen gas, the temperature was raised to 240 ℃ by step reaction. The condensation reaction was carried out for about 3 to 4 hours to obtain a thermosetting polyester polyol having an acid value of 38 and a dilution viscosity (K-150 75% dilution; Gardner) of Z to Z1 as the condensation reaction product.

Example 1

Water Soluble Polyester Resin

A 2-liter four-necked flask was equipped with a thermometer, condenser, stirrer, and condenser, and a temperature raising device was attached. The bifunctional alcohol of carboxyl group-containing polyester polyol, trimellitic anhydride, methyl propanediol, and neopentylglycol which were synthesize | combined by the said synthesis example was put here, and the temperature was heated up 200 degreeC. The condensation reaction was performed for about 1 to 2 hours to obtain a resin having an acid value of 33 and a dilution viscosity (K-150 75% dilution; Gardner) of Z 2 to Z 3 as the condensation reaction product. After lowering the temperature to 80 ℃ and neutralized by adding tetraethyl alcohol (TEA). After neutralizing and maintaining for about 30 minutes, water (DIW) is added dropwise over 20 minutes, and dispersed in water. When water was added, the mixture was maintained at a low viscosity state through the initial high viscosity state and the temperature was lowered to room temperature, followed by filtering by 200mesh to obtain a water-soluble polyester resin.

Example 2

Manufacture of paint

To the water-soluble polyester resin, Bayer PUD resin according to the blending ratio of Table 1, water (DIW), a wet dispersant (BYK, Disperbyk 184) was added and stirred for 10 minutes, titanium dioxide was added and stirred for more than 30 minutes. After that, the antifoaming agent (BYK, BYK 037) and the freezing stabilizer are added in order, and each time the respective substances are added, the mixture is sufficiently stirred for a predetermined time. Then, a curing agent (BYK, WT2102) was added and sufficiently stirred to form a water-soluble plastic coating paint.

TABLE 1

Raw material name Compound amount (% by weight) Resin of Synthesis Example 1 21.2 Bayer PUD Resin 35.4 Water (DIW) 15 Freeze Stabilizer 0.2 Antifoam 0.3 Wet Dispersant 0.5 Bayer Curing Agent 12.1 Titanium dioxide 15.3 system 100

Comparative Example 1

Except for the resin of Example 1 in the coating composition of Example 2, only 56.6% by weight of Bayer PUD resin was used alone to prepare a paint in the same manner as in the coating method of Example.

Paint evaluation

The paints obtained in Example 2 and the paints obtained in Comparative Example 2 were spray-coated onto the specimens, respectively, and cured at 80 ° C. for 30 minutes, and then the physical properties of the formed coating films were evaluated.

[Table 2] Property evaluation results of the coating film

Example 2 Comparative Example 1 Soft Feel 3 One Wear resistance 2 2 Light resistance 2 2 Coating flexibility 3 One

(3 = good, 2 = normal, 1 = bad)

Physical property evaluation method of coating film

1) Soft Feel

The surface of the coating film is observed after complete coating.

-Rub each finger to evaluate each texture in relative comparison.

-Compared to the softness of the leather feel.

2) wear resistance

-Mark the presence of scratches when the surface of coating film is reciprocated 100 times with fixed wheel of 1kg load after complete curing of coating film.

3) light resistance

-It shows the degree of change in gloss when the surface of coating is exposed to sunlight for a long time after complete curing of coating.

4) Flexibility of coating

-After hardening the coating film, the surface of the coating film is peeled off and pulled out by both hands to indicate the degree of breakage.

The water-soluble plastic coating material having the above-described composition can provide a soft feeling to the interior door of the paint door to the interior material for automobile interior and at the same time eliminate the use of volatile solvents to minimize environmental pollution. In addition, as shown in the embodiment of Table 2, it has a finite abrasion resistance with conventional plastic coating paint and at the same time has a superior soft feeling and flexibility.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified without departing from the spirit and scope of the invention described in the claims below. And can be changed.

Claims (10)

A water-soluble poly of a stereoscopic network having a carboxyl group at both ends and having a polyester polyol having a hydroxyl value of 50 to 120 mgKOH / g and having a weight average molecular weight of 1,500 to 3,000 and an ester chain added to the polyester polyol. 15 to 28% by weight ester resin; 15 to 45 weight percent polyurethane dispersion resin; 8 to 16 weight percent curing agent; Titanium oxide 11 to 20% by weight; 0.5 to 2 weight percent of an additive; And Include extra water, The carboxyl group-containing polyester polyol contains a 30 to 40% carboxyl group, the water-soluble paint for a plastic coating for automotive interiors, characterized in that the molecular weight is 1000 to 3000. delete The step of while gateu a carboxyl group at both terminals contains the carboxyl group of 30 to 40%, and the minute jaryang a divalent condensation reaction by putting the acid and alcohol in the polyester polyol of 1000 to 3000, a hydroxyl value of 50 to 120 mgKOH / g; Neutralizing the first reactant obtained by the condensation reaction and having an acid value of 30 to 40 by adding an amine compound; Water dispersing the second reactant formed by the neutralization using water; The polyester resin formed by water dispersion is added with a bifunctional alcohol and an acid to react to include a polyester polyol having a hydroxyl value of 50 to 120 mgKOH / g while having a carboxyl group at the terminal, and having a weight average molecular weight of 1,500 to 3,000. Water-soluble polyester resin manufacturing method characterized in that to form a water-soluble polyester resin of a three-dimensional network structure having an ester chain added to the polyester polyol. delete delete It contains a polyester polyol having 30 to 40% of carboxyl groups, having a carboxyl group at both ends, having a molecular weight of 1000 to 3000 and a hydroxyl value of 50 to 120 mgKOH / g, and having a weight average molecular weight of 1,500 to 3,000 . Providing a water-soluble polyester resin having a three-dimensional network structure in which an ester chain is added to the polyester polyol; And 15 to 28% by weight of the water-soluble polyester resin, 15 to 45% by weight of polyurethane dispersion resin, 8 to 16% by weight of curing agent, 11 to 20% by weight of titanium thioxide, 0.5 to 2% by weight of additives and excess water Method for producing a water-soluble plastic coating paint comprising the step of preparing a mixed water-soluble resin. The method of claim 6, wherein the polyester polyol 1,4-butylene glycol, 2,3-butylene glycol, 1,3-butylene glycol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,3-pentanediol, 2-methyl- At least one difunctional alcohol and trifunctional trimetholol propane selected from the group consisting of 2,4-pentanediol and methylpropanediol are condensed with an alcohol and a divalent acid in which the alcohol is mixed in an equivalent ratio of 1: 0.1 to 0.4 Method for producing a water-soluble plastic coating paint, characterized in that formed. The method of claim 7, wherein the diacid comprises 50 to 100% of an alicyclic diacid and 0 to 50% by weight of an aliphatic diacid. The method of claim 6, wherein the polyester polyol is 55 to 67 parts by weight of 2-methyl-2,4-pentanediol, 8 to 15 parts by weight of 1,6-hexanediol, 2-methyl-1,3-pentanediol 8 To 16 parts by weight, trimethylolpropane 4 to 9 parts by weight, adipic acid 30 to 50 parts by weight, hexahydrophthalic hydride 95 to 130 parts by weight of the condensation reaction is produced to produce a water-soluble plastic coating Way. The method of claim 6, wherein the water-soluble polyester resin Condensation reaction by adding dihydric acid and alcohol to the polyester polyol; Neutralizing the first reactant obtained by the condensation reaction and having an acid value of 30 to 40 by adding an amine compound; Water dispersing the second reactant formed by the neutralization using water; And And adding a bifunctional alcohol and an acid to the polyester resin formed by dispersing the water.