KR20080105447A - Paint composition for high weatherability PCM exterior materials - Google Patents

Abstract

The present invention relates to a coating composition for high weatherability PCM exterior materials, and more particularly, to a copolymerized polyester resin prepared by copolymerizing an aromatic polyacid and an alicyclic polyacid, a melamine curing agent, a curing accelerator, a viscoelastic modifier, a dispersing agent, and the like. Thus, when applied to the conventional hot air curing method, as well as the near-infrared curing method, the present invention relates to a high weather resistance PCM coating material composition having excellent physical properties such as appearance, flexibility, solvent resistance, chemical resistance, and weather resistance.

Description

Paint and varnish composition having a high weatherproof for PCM}

The present invention relates to a coating composition for high weatherability PCM exterior materials, and more particularly, to a copolymerized polyester resin prepared by copolymerizing an aromatic polyacid and an alicyclic polyacid, a melamine curing agent, a curing accelerator, a viscoelastic modifier, a dispersing agent, and the like. Thus, when applied to the conventional hot air curing method, as well as the near-infrared curing method, the present invention relates to a high weather resistance PCM coating material composition having excellent physical properties such as appearance, flexibility, solvent resistance, chemical resistance, and weather resistance.

At present, PC steel sheet is not only excellent in various physical properties such as flexibility, adhesion, chemical resistance, weather resistance, and corrosion resistance, but also is widely used in various industrial fields such as building interior and exterior materials and home appliances due to thin film coating and high speed line.

However, in spite of these advantages, the hot air curing method, which is mainly applied as a coating method of the currently applied PCM steel sheet, has a long oven facility and may be heated for a long time at a high temperature, resulting in excessive heat transfer to the base material, which may affect the properties of the base material. In addition, the solvent discharge is severe, there is a problem such as the generation of odor and smoke during work.

Therefore, as well as solving the above problems, the interest of the near-infrared curable PCM steel coating material is increasing as a way to improve the productivity and energy efficiency.

The near-infrared curing method is a method in which a coating film is formed by curing by thermal energy emitted from a short wavelength infrared heat source of about 800-1500 nm. Near-infrared emitters are emitted from near-infrared lamps with a surface temperature of 2000 to 3500 ° K and have a high energy density of 100 to 800 kW / m ² .

In general, curing of a coating film by a near-infrared irradiator may be achieved by crosslinking being formed by free radical polymerization of an olefin double bond by a thermal initiator or condensation of an appropriate functional group.

However, the coating film cured by radical polymerization by thermal initiator does not satisfy the properties required by PC steel sheet, and most of the line equipments are hot air drying type, which can be applied to both hot air curing method and near infrared curing method. It is a situation that paint can be required. In addition, near-infrared curing is hardened for a very short time due to the characteristics of the curing method, so the solvent discharge time is short, and it is difficult to ensure excellent appearance, and also to secure the stability of coating film properties such as workability, curing degree, and weather resistance. There is this.

U.S. Patent No. 6,541,078 describes a method of mixing a resin having an olefinic double bond and a resin having an appropriate functional group in such a near-infrared curing method, or curing using a resin having an olefinic double bond and an appropriate functional group at the same time.

However, this is to be applied to automotive clear paints, it is difficult to apply to the conventional hot air curing method of the PM paint coating method, and does not exhibit the physical properties required by the PC steel sheet.

An object of the present invention is not only excellent in physical properties such as appearance, bendability, solvent resistance, chemical resistance, weather resistance, etc. when applied to the conventional hot air curing method, but also near-infrared curing method of the coating film formed by curing with a near-infrared irradiator It is to provide a coating composition for a high weather resistance PCM exterior material which exhibits physical properties equivalent to or higher even when the maximum firing temperature is lower than the maximum firing temperature of the coating film cured by a hot air oven.

The high weather resistance PCM coating material composition of the present invention is 30 to 70% by weight of copolymerized polyester resin prepared by copolymerizing aromatic polyhydric acid and cycloaliphatic polyacid, 5 to 40% by weight of melamine curing agent, 0.5 to 3 weight of curing accelerator %, Viscoelasticity modifier 0.1 to 5% by weight, pigment 10 to 50% by weight, dispersant 0.1 to 5% by weight and an organic solvent 10 to 40% by weight.

The copolyester resin used in the present invention is a polyester resin obtained by mixing and copolymerizing an aromatic polyacid and an alicyclic polyacid. In general, the weather resistance is the absolute factor of weather resistance in the actual outdoor exposure of the coating film. In addition to the ultraviolet rays, humidity conditions and thermal change conditions are important. In the case of polyester resins prepared using only cycloaliphatic polyacids, the ultraviolet resistance of the coating film is excellent but relatively glassy. Since the transition temperature and the water resistance are inferior, the weather resistance is weak due to the thermal change at the time of actual exposure, and therefore, a polyester resin copolymerized using an alicyclic polyacid and an aromatic polyacid must be used. In the case of using such a copolyester resin, it is possible to manufacture a paint provided with all of ultraviolet ray resistance, water resistance and heat resistance.

In order to prepare the copolyester resin, the aromatic polyacid and the alicyclic polyacid are mixed in a molar ratio of 1: 3 to 5, and when the molar ratio of the cycloaliphatic polyacid to the aromatic polyacid is less than 3, ultraviolet resistance is lowered. There is a possibility that the weather resistance of the coating film is lowered. When it exceeds 5, the water resistance and the heat resistance of the coating film may be lowered, and finally the weather resistance may be lowered at the time of outdoor exposure.

As the aromatic polyacid, for example, at least one selected from phthalic anhydride, terephthalic acid, isophthalic acid, trimaleic anhydride and ester derivatives thereof can be used, and as the alicyclic polyacid, for example, 1,4-cyclohexane At least one selected from ci dicarboxylic acid, hexahydro phthalic anhydride, methylhexa hydro phthalic anhydride, methyl tetra hydro phthalic anhydride, tetra hydro phthalic anhydride and ester derivatives thereof can be used.

The copolyester resin according to the present invention preferably has a number average molecular weight of 800 to 6,000, a glass transition temperature of -15 to 40 ° C, and a hydroxyl group (OH Value) of 10 to 100 mgKOH / g. When the property of the copolyester resin is out of the above range, there is a problem that after forming the coating film, workability decreases, curability decreases, poor appearance.

In the present invention, it is preferable to use the copolyester resin in 30 to 70% by weight of the total coating composition, if the content is less than 30% by weight, the flexibility and impact resistance of the coating film is greatly reduced, exceeding 70% by weight There is a problem that fouling resistance, solvent resistance, and hardness of the coating film are rapidly lowered.

In addition, in the present invention, a melamine resin is used as a curing agent, which may be a methoxy melamine resin having a molecular weight of 300 to 1000, or a methoxy / butoxy mixed melamine resin, and preferably a methoxy melamine resin may be used. Can be. Since the methoxy type melamine resin or the methoxy / butoxy mixed type melamine resin is smaller than the butoxy type in its molecular weight, the melamine concentration on the surface becomes easier, and thus the melamine self-condensation of the surface when the tertiary amine dissociates. Curing with a resin layer improves, and an overall hardened coating film can be obtained.

The methoxy-type melamine resin may be used that is obtained by the polymerization of methanol and formaldehyde. Examples of commercially available methoxy melamine resins for use in the present invention include CYMEL-303, CYMEL325, CYMEL-327, CYMEL-350 or CYMEL-370 (CYTEC), RESIMINE-7550, RESIMINE-717, RESIMINE730, RESIMINE747 or RESIMINE-797 (SOLUTIA), BE-3717, BE-370 or BE3747 (BIP). Examples of butoxy / methoxy mixed melamine resins include RESIMINE-755, RESIMINE-757 or RESIMINE-751 (SOLUTIA), CYMEL-1168, CYMEL-1170 or CYMEL-232 (CYTEC).

In case of using butoxy melamine resin alone as a curing agent or simply mixing methoxy melamine resin and butoxy melamine resin instead of methoxy / butoxy mixed melamine resin, the melamine paint has a poor compatibility with polyester resin. It is transferred to the upper layer of, which causes not only the weather resistance of the coating film is lowered but also the gloss of the coating film is lowered.

In the present invention, the melamine curing agent is preferably used at 5 to 40% by weight of the total coating composition, if the content is less than 5% by weight, fouling resistance and solvent resistance is sharply lowered, the content is 40% by weight When it exceeds, the flexibility and impact resistance of a coating film fall, and it is unpreferable.

The coating composition of the present invention promotes the curing of the polyester resin and the melamine curing agent by including a curing accelerator to improve the density of the coating film. In this case, as the curing accelerator, epoxy resin shielded or secondary amine shielded sulfonic acid may be used.

As the sulfonic acid, for example, p-toluenesulfonic acid, dodecylbenzenedisulfonic acid, dinonylnaphthalene disulfonic acid, dinonylnaphthalenesulfonic acid, or the like can be used, and p-toluenesulfonic acid or dinonylnaphthalenesulfonic acid is preferable.

In this case, the sulfonic acid is preferably shielded with a material that can be dissociated by heat, and as the shielding material, an epoxy resin or a secondary amine is used. In the near-infrared curing method, an epoxy resin shielded sulfonic acid is preferable. In the near-infrared curing method in which an epoxy resin-shielded sulfonic acid is used, the curing time may be delayed more rapidly than in the case of using a sulfonic acid shielded with a secondary amine. It is possible to reduce the occurrence of popping of the coating film and to improve appearance.

In the present invention, the curing accelerator is used in 0.5 to 3% by weight of the total coating composition. When the content of the curing accelerator is less than 0.5% by weight, curing of the coating film may be insufficient depending on the working conditions, so that it may not maintain proper stain resistance. When the content of the curing accelerator exceeds 3% by weight, curing of the coating film may occur so rapidly that during painting work. Popping occurs or shrinkage of the coating film occurs.

In the present invention, the viscoelasticity modifier may be a viscoelasticity modifier generally used in the art, with silica and ammonium compounds being preferred. It is preferable to use 0.1 to 5% by weight of the total coating composition, if the content is less than 0.1% by weight, the storage stability effect is insignificant, and if it exceeds 5% by weight, it will not increase the price and harden to form a dense coating film. There are disadvantages.

In the present invention, as the pigment, organic or inorganic pigments may be used without limitation. As the pigment, it is preferable to use a pigment capable of imparting heat resistance and chemical resistance suitable for PCM paint. In addition, the basic particles of the pigment should also be sufficiently considered. Examples of such pigments include cyanine blue, titanium oxide white, iron oxide red, carbon black, and the like, and sieving pigments such as minusil, talc, clay, silica, aluminum hydroxide compounds, and the like. This can be used.

Due to the characteristics of the near-infrared curing method, the required calorie content varies depending on the color of the coating film and the pigment component used. Since this is related to energy saving, it is preferable to select a pigment having excellent coating properties and low heat requirements.

It is preferable to use 10-50 weight% of a pigment in all the coating compositions, and when the content is less than 10 weight%, hiding power falls and when it exceeds 50 weight%, weather resistance falls.

The dispersant used in the present invention is used to control the rheology of the paint, and such materials include unsaturated carboxylic acids having a carboxyl group and an amine group attached to the terminal of the molecular structure, and to prevent color separation and pigment precipitation, Modified polyurethane, which is a type dispersant, may be mixed without particular limitation, and it is preferable to mix 70 to 90% by weight based on the total content of the dispersant.

Commercially available dispersants include P104, DISPER BYK130, DISPER BYK160, DISPER BYK170, DISPER BYK173, ANTITERRA-U, etc., and EFCA products, EFCA-776, EFCA-4050, EFCA-4063, and EFCA-4051. CFC-604 is suitable for TEGO Corporation.

It is preferable to use 0.1 to 5% by weight of the dispersant in the total coating composition, when the content is less than 0.1% by weight, color separation or pigment precipitation occurs, and when it exceeds 5% by weight, the rheology is lowered.

The content of the dispersant is generally controlled according to the content of the pigment, and the productivity and blending stability of the paint are also considered. When the pigment used is an organic pigment, the ratio is increased, and in the case of an inorganic pigment, it is preferable to reduce the ratio. When using an organic pigment, the content of the dispersant is 2 to 5% by weight, and an inorganic pigment is used. 0.1 to 2% by weight is preferable.

In the production of the coating composition of the present invention, it is preferable to use alcohols, aromatic hydrocarbons, acetates, ketones or mixtures thereof as organic solvents, and aromatic hydrocarbons or acetates or mixtures thereof are more preferred. desirable. By using a solvent having good solubility in the polyester resin, it is possible to minimize the solvent content in the coating composition to prevent popping (popping) that may occur due to a short curing time.

The content of the organic solvent is preferably 10 to 40% by weight based on the total coating composition, if the content is less than 10% by weight, workability deterioration occurs, if the content exceeds 40% by weight, popping ) Is easy to occur and reduces paint storage.

In addition to the above components, the coating composition of the present invention may further include a leveling agent that has been conventionally applied.

Cold rolled steel, zinc hot dipping steel, electro-zinc steel, alloy-plate steel, copper sheet and tin-plate steel, etc. may be used as a coating steel material that can be used in the paint of the present invention, and among them, mainly used Examples of the material include cold rolled steel (CR), electro-zinc steel (EGI), zinc hot dipping steel (GI), and alloy-plate steel (GA).

In addition, phosphate, chromate or the like may be used as a pretreatment of the material used.

Although there is no restriction | limiting in particular as a coating method of the coating composition which concerns on this invention, roll coating is preferable, and the coating film thickness used for coating is 5-25 micrometers.

The baking condition differs depending on the hot air curing method or the near infrared curing method.

In the case of the hot air curing method, the baking time can be changed according to the baking conditions, and it is preferable to bake for 35-40 seconds at the temperature of 250-280 ° C in the painting condition of the PCM.

In the case of the near-infrared curing method, the coating film is cured by adjusting the near-infrared emitter power or the baking time. In general, the baking time of the near-infrared curing method is 2 to 10 seconds, but the curing time depends on the color and composition of the paint. Since the required amount of heat to be satisfied varies, it is preferable to adjust the baking conditions suitable for the color and composition of the paint.

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

Example  And Comparative example

Following the composition and content of Table 1, a polyester coating composition was prepared as follows.

1 / of Cocosol # 100 (KOCOSOL # 100, SK Co., Ltd.) / PM glycol ether acetate (PMA GLYCOL ETHER ACETATE, manufactured by Dow Chemical Co., Ltd.) as an organic solvent 1 Add 35 g of mixed solution, add TiO ₂ (manufactured by Ishihara, Japan, or DuPont), a dispersant, and a viscoelastic modifier to a 1 L tin container, and then mix the glass beads having a diameter of 1-2 mm with the solution. , Shake type dispersion machine (RED DEVIL, KCC Co., Ltd.) was dispersed for 1 hour 30 minutes. The particle size after dispersion was adjusted to 5 μm or less.

Resin (1/2 of the total amount used), melamine curing agent, curing accelerator were added to the master batch prepared in Table 1, and acrylic leveling agent was added to obtain coating appearance adjustment and antifoaming effect. The viscosity of the final paint was adjusted to 100 seconds / Ford Cup # 4, 25 ° C.

The composition of Table 1 was prepared based on the solid content, and the solvent used in the paint was excluded. Solvents used in paints were used to control the fluidity and viscosity required to prepare the paints.

TABLE 1

(Unit: g)

ingredient Raw material name Example Comparative example One 2 3 4 One 2 3 Suzy CRF00231 80 CRF00167 80 80 80 80 SK-2327 80 60 D-145 20 Melamine curing agent CYMEL303 20 20 10 10 20 10 20 CYMEL325 10 10 Curing accelerator NACURE 1953 3 3 NACURE 1419 3 3 3 One 2 Ten initiators INITIATOR BK One One Dispersant CFC-604 0.1 0.1 0.1 0.1 0.2 0.2 0.2 EFCA-4050 0.4 0.4 0.4 0.4 0.3 0.3 0.3 Viscoelastic regulator BENTONE 38 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Leveling agent POLY FLOW 90/50 0.3 0.3 0.3 0.3 0.3 0.3 0.3 URAD DD-27 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Pigment TiO ₂ 50 50 50 50 50 50 50 YELLOW 29 5 5 5 5 5 5 5 CA-0020 40 40 40 40 40 40 40 Organic solvent Cocosol # 100 / PM Glycol Ether Acetate 1/1 Solution 35 35 35 35 35 35 35

Description of each raw material name of the said Table 1 is as follows.

1. CRF00231: KCC manufactured, polyester resin polymerized with aromatic polyacid, number average molecular weight 3,000, glass transition temperature 10 degreeC, hydroxyl value 40 mgKOH / g.

2. CRF00167: KCC Co., Ltd., a polyester resin polymerized by mixing an aromatic polyacid and an alicyclic polyacid, a number average molecular weight of 4,500, a glass transition temperature of 20 ℃, a hydroxyl value of 35 mgKOH / g.

3. SK-2327: manufactured by Dupont, urethane-modified acrylate resin, hydroxyl value 70mgKOH / g.

4. D-145: Dupont, polyester resin.

5. CYMEL303: manufactured by CYTEC, methoxy type melamine resin, molecular weight 1000 or less.

6. CYMEL325: CYTEC company, imino type methoxy type melamine resin.

7. NACURE 1953: from KING, dinonylnaphthalenesulfonic acid masked with secondary amines.

8. NACURE 1419: KING, made of dinonylnaphthalenesulfonic acid shielded with epoxy resin.

9. INITIATOR BK: A benzopinacol compound from LANXESS.

10. CFC-604: Cheongwoo Co., unsaturated carboxylic acid dispersant.

11. EFCA-4050: product of EFCA, modified polyurethane, and polymeric dispersant.

12. BENTONE 38: product of TROMYD, an ammonium compound.

13. POLY FLOW 90/50: Co., Ltd. product, acrylic copolymer, acrylic leveling agent.

14. URAD DD-27: A product made by ICI, an acrylic leveling agent.

15. TiO ₂ : CR-97 manufactured by Ishihara Corporation, Japan.

16. YELLOW 29: HONEY YELLOW 29 manufactured by SHEPHERD.

17. CA-0020: A product of Korea Semiconductor Corporation, silica having an average particle size of 3 μm or less.

Experimental Example

After coating the coating compositions of Examples 1 to 4 and Comparative Examples 1 to 3 with a base material, the coating films were prepared by baking by hot air curing and near infrared curing.

The base material used was 0.45mm GI (Galvanize Iron), and the plated zinc content was 87mg / m ² , and the coating degree was 5 ~ 7㎛ using EJ2751-Y005 (product of KC Corporation), an epoxy modified polyester primer. Bar coating (No # 14). The material pretreatment of the GI material was subjected to NRC (Non Rinse Chromate, manufactured by Parkerizing Co., Ltd.), and the throughput was applied at 20-40 mg / m ² .

At the time of coating curing, the baking conditions of the hot air curing method were 280 ° C. × 35 seconds and a wind speed of 2 m. The maximum temperature of the baking film was adjusted to 224˜232 ° C. The baking condition of near-infrared curing method was 3 modules x 3 seconds (actual curing time), and the maximum temperature of the baking film was adjusted to 210 ~ 216 ℃.

In the case of the hot air curing method, an automatic discharge oven (manufactured by Taesung Engineering Co., Ltd.) was used, and in the case of the near-infrared curing method, a near-infrared irradiator (product of German Adfoss Co., Ltd.) was used.

The physical properties of each coating film were measured by the following method, and the results are shown in Table 2.

Experiment method

1. Appearance

The degree of popping of the coating film was evaluated.

-Evaluation score: The case where there was no popping was made into the high value, the case where the popping generate | occur | produced in the whole coating film was made into the low value, the case where there was no popping was set as 5, and the case where the papping occurred in the whole coating film was evaluated.

2. Gloss (GLOSS 60 °)

60 ° gloss was measured using a gloss machine from BYK or SHEEN.

3. Hardness

-The scratch of the coating film was evaluated using the Uni Pencil of Mitsubishi, Japan.

4. Processability

Two materials of the same thickness as the material were put at room temperature and processed 180 °, and the peeled state and the crack state were evaluated by winding the processed part with Scotch tape.

-Evaluation score: The case where there was no crack was made into high value, the case where a crack generate | occur | produced and peeled off was made into a low value, and the case where crack was generated was 5 and the case where cracks generate | occur | produce and peeled all over was evaluated as 1.

5. Acid resistance

5% hydrochloric acid solution was applied to the coating film, and then the surface was covered and the periphery was shielded with petroleum jelly, which was left at 25 ° C. for 24 hours, and the condition of the coating film was evaluated.

-Evaluation score: The thing with no trace was made into the high value, and the thing peeled off was made into the low value, and the case where there was no trace was evaluated as 5 and the case where the whole peeled off was 1.

6. Base resistance

5% sodium hydroxide solution was applied to the coating film, and then the surface was covered and the periphery was shielded with petrolatum, which was left at 25 ° C. for 24 hours, and the condition of the coating film was evaluated.

-Evaluation score: The thing with no trace was made into the high value, and the thing peeled off was made into the low value, and the case where there was no trace was evaluated as 5 and the case where the whole peeled off was 1.

7. Solvent resistance

The number of times the methyl ethyl ketone (MEK) was buried in gauze and reciprocated with a load of 1 kg was measured.

8. Q.U.V-A 2000 hours gloss retention and discoloration evaluation

Using a QUV-se instrument manufactured by US Q-PANEL, the UV wavelength was adjusted to A Type (340 nm), the cycle was irradiated at 60 ° C for 8 hours, and condensed at 50 ° C for 4 hours to give an initial gloss of coating. After the contrast test, the gloss was compared and the color difference was measured (color difference meter, manufactured by Minolta) to evaluate the gloss retention rate and the degree of discoloration (ΔE).

9. Q.U.V-B 1000 hours gloss retention and discoloration evaluation

Using a QUV-se instrument manufactured by Q-PANEL in the United States, the UV wavelength was adjusted to B Type (313 nm), and the cycle was irradiated at 60 ° C. for 8 hours, and condensed at 40 ° C. for 4 hours to obtain an initial coating film. After the glossiness test, the gloss was compared and the color difference was measured (color difference meter, manufactured by Minolta) to evaluate gloss retention and discoloration degree (ΔE).

TABLE 2

Item Curing method Example Comparative example One 2 3 4 One 2 3 Popping sirocco 5 5 5 5 5 5 5 Near infrared ray 5 5 5 5 5 5 4 Gloss (GLOSS 60 °) sirocco 82 85 84 85 83 82 84 Near infrared ray 80 83 85 83 84 85 82 Hardness sirocco H 2H H H F H F Near infrared ray 2H 2H H 2H H H H Machinability sirocco 4 4 5 4 4 2 3 Near infrared ray 4 4 4 4 4 2 3 Acid resistance sirocco 5 5 5 5 5 5 5 Near infrared ray 5 5 5 5 5 5 5 Basic resistance sirocco 5 5 5 5 5 5 5 Near infrared ray 5 5 5 5 5 5 5 Solvent resistance sirocco 100 ↑ 100 ↑ 100 ↑ 100 ↑ 100 ↑ 100 ↑ 100 ↑ Near infrared ray 100 ↑ 100 ↑ 100 ↑ 100 ↑ 100 ↑ 100 ↑ 100 ↑ Q.U.V- A 2000 hours Glossiness retention rate (%) sirocco 82 85 80 84 21 50 48 Near infrared ray 84 87 83 88 29 56 52 △ E sirocco 1.4 1.7 1.2 2.1 1.6 2.2 1.5 Near infrared ray 1.7 1.6 1.0 2.3 2.3 1.9 1.5 Q.U.V- B 1000 hours Glossiness retention rate (%) sirocco 81 85 82 83 32 58 53 Near infrared ray 91 88 78 86 29 57 51 △ E sirocco 1.6 1.5 1.8 1.7 1.6 1.2 0.9 Near infrared ray 0.9 1.3 1.1 1.6 1.5 1.5 0.7

As shown in Table 2, the coating composition according to the present invention exhibits the physical properties represented by the appearance and the acid resistance, base resistance and solvent resistance expressed in the popping and gloss, the equivalent or more than the physical properties compared to the comparative example Processability and hardness showed better properties than the comparative example. In particular, the gloss retention rate shown in Q.U.V-A, B shows a big difference, indicating that the weather resistance is excellent.

In addition, the physical properties of both the near infrared curing method and the hot air curing method were equivalent.

As described above, the coating composition according to the present invention is not only excellent in weather resistance, acid resistance and base resistance, but also in the near-infrared curing method can improve energy efficiency due to short curing time and reduction of production equipment, and can reduce environmental pollution. In addition, there is an advantage that the speed of the line is easy.

Claims (7)

30 to 70% by weight of copolymerized polyester resin prepared by copolymerizing aromatic and alicyclic polyacids, 5 to 40% by weight of melamine curing agent, 0.5 to 3% by weight of curing accelerator, 0.1 to 5% by weight of viscoelastic modifier, pigment 10 to 50% by weight, 0.1 to 5% by weight of the dispersant and 10 to 40% by weight of the organic solvent, characterized in that the coating composition for a high weather resistance PCM exterior material. The coating composition of claim 1, wherein the coating composition is cured by hot air curing or near-infrared curing to form a coating film. The method of claim 1, wherein the aromatic polycarboxylic acid is at least one selected from phthalic anhydride, terephthalic acid, isophthalic acid, trimaleic anhydride and ester derivatives thereof, and the cycloaliphatic polyacid is 1,4-cyclohexy dicarboxylic acid, hexahydro phthalic. It is at least one selected from anhydride, methylhexa hydrophthalic anhydride, methyl tetra hydrophthalic anhydride, tetrahydro phthalic anhydride and ester derivatives thereof. . The coating material of claim 1, wherein the copolymer polyester resin has a number average molecular weight of 800 to 6000, a glass transition temperature of -15 to 40 ° C, and a hydroxyl value of 10 to 100 mgKOH / g. Composition. The coating composition of claim 1, wherein the copolymer polyester resin has a molar ratio of aromatic polyacid: alicyclic polyacid of 1: 3 to 5. The coating composition of claim 1, wherein the melamine curing agent is a methoxy melamine resin or a methoxy / butoxy mixed melamine resin. The coating composition of claim 1, wherein the curing accelerator is sulfonic acid shielded with epoxy or secondary amine.