KR20170132555A - The Primer Painting Composition Applied To The Surface Of Chromium Coating And The Method Of Manufacturing Therefor - Google Patents

Abstract

The present invention relates to a primer coating composition applied to a chromium-coated surface and a method for preparing the primer coating composition, and it is an object of the present invention to simplify the process by omitting the base coating by including an organic pigment- To a coating composition and a method for producing the same.
According to the present invention, there is provided a primer coating composition comprising a polyester resin, an adhesion promoter, a reaction catalyst, an organic / inorganic pigment-dispersed colorant, a wetting additive and a solvent, .

Description

TECHNICAL FIELD [0001] The present invention relates to a primer coating composition applied to a chromium-coated surface and a method for producing the primer coating composition.

The present invention relates to a primer coating composition applied to a chromium-coated surface and a method for producing the primer coating composition, and more particularly, to a primer coating composition for improving durability by simplifying a process by omitting base coating by including an organic- Compositions and methods for their preparation.

In recent years, automobiles have been increasing in number of parts requiring various designs and functions as part of high-end in order to meet the demands of the users. In particular, external parts of automotive parts are chrome-plated to achieve various colors to achieve high-quality parts, and chrome-plated parts require not only appearance but also improved durability such as water resistance and chipping resistance.

The types of chromium plating applied to vehicles are trivalent chromium or hexavalent chromium, which are classified into bright and semi-bright. The trivalent chromium plating is superior to the hexavalent chromium plating and has excellent resistance to stain resistance and has a high processing cost compared to hexavalent chromium. However, there is a disadvantage that 6-chrome plating is less resistant to scratching than trivalent chrome plating, but the processing cost of 6-chrome plating is lower than that of 3-chrome plating. .

Accordingly, the present invention aims to enhance the durability of parts with chromium on the chrome while realizing colors similar to trivalent chrome by applying paint to general hexavalent chromium plating. In the case of a radiator grill, the thickness of the plating is not uniform depending on the shape of the part, which causes a problem of poor durability.

On the other hand, in the prior art, in order to coat the surface of the chromium plating, the adhesion with the plating layer must be a basic property, but chromium plating generally has the property of hard coating. Therefore, a primer made of chlorinated polyolefin as a main resin is used for imparting adhesion properties to the plating layer. Also, it is painted with a primer / base / clear coating system to satisfy the required properties. As described above, the paint applied to the chrome plating of the prior art mainly consists of the coatings which are concealed by the coating of three layers, and the coating process of the three layers is performed, thereby increasing the cost of the coating process. In addition, there is a problem in that the plating is concealed while being coated, and the unique metallic feel of chrome plating is concealed.

It is an object of the present invention to provide a primer coating composition which is applied to a chromium-coated surface having improved durability of chromium plating.

Another object of the present invention is to provide a method of manufacturing a primer coating composition which is applied to a chromium-coated surface that simplifies the manufacturing method and reduces the manufacturing cost by omitting one step of the manufacturing method.

The technical objects to be achieved by the present invention are not limited to the technical matters mentioned above, and other technical subjects which are not mentioned can be clearly understood by those skilled in the art from the description of the present invention .

According to the present invention, there is provided a primer coating composition comprising a polyester resin, an adhesion promoter, a reaction catalyst, an organic / inorganic pigment-dispersed colorant, a wetting additive and a solvent, .

In the present invention, the polyester resin is 40 to 70 wt%, the adhesion promoter is 2 to 5 wt%, the reaction catalyst is 0.1 to 1.5 wt%, the organic pigment dispersion colorant is 0.1 to 2.0 wt% %, The wetting additive is 0.5 to 2.0 wt%, and the solvent is 20 to 40 wt%.

In the present invention, the polyester resin preferably has a solid content of 50% by weight of the total weight of the polyester resin, an average molecular weight of 20,000 to 40,000, and a content of hydroxyl groups of 0.1 to 1.0%.

In the present invention, the polyester resin may be at least one selected from the group consisting of trimellitic acid, trimellitic anhydride, pyromellitic dianhydride, trimethylolpropane, glycerol, pentaerythritol, citric acid, It is preferred that the polyfunctional monomer comprises at least one polyfunctional monomer.

In the present invention, the polyester resin may be at least one of trimellitic anhydride, pyromellitic anhydride, glycerol, sorbitol, 1,2,6-hexanetriol, pentaerythritol, trimethylolethane and trimesic acid It is preferable to include a polyfunctional monomer residue.

In the present invention, it is preferable that the adhesion-promoting agent is epoxy-functional methoxysilane at glycidoxin.

In the present invention, the reaction catalyst is preferably dibutyltin dilaurate.

In the present invention, it is preferable that the wetting additive is a polydimethylsiloxane series.

In the present invention, it is preferable that the solvent is a mixture of one or more selected from the group consisting of esters and hydrocarbons.

In the present invention, it is preferable that the organic-inorganic pigment-dispersed colorant is dispersed at a nanometer size of 150 to 300 nm.

In the present invention, it is preferable to further include a hexamethylene diisocyanate trimer system as a curing agent, and the weight ratio of the above-mentioned curing agent to the curing agent is preferably 10: 1.

According to another aspect of the present invention, there is provided a method of manufacturing a chromium-coated surface, comprising: mixing a primer coating composition applied to a chromium-coated surface into a reactor; An ester reaction step in which the mixed primer coating composition is ester-reacted; And a polyester condensation reaction step in which the ester-reacted primer coating composition is subjected to a polyester condensation reaction. The present invention also provides a method for preparing a primer coating composition.

In the present invention, it is preferable that the mixing step is performed such that the reactor is maintained at 200 to 230 ° C.

In the present invention, it is preferable that the ester reaction step removes ester condensation by-products having a low molecular weight.

In the present invention, it is preferable that the ester reaction is terminated based on the point of time when the conversion rate of the ester reaction is at least 95% of the total outflow amount of the low molecular weight ester by-product.

In the polyester condensation reaction step, the reactor is preferably maintained at 250 to 280 ° C.

In the present invention, it is preferable that the polyester condensation reaction step is stopped at an acid value of 2 to 4 KOH / g.

According to the primer coating composition applied to the chromium-coated surface of the present invention, there is an effect of providing a primer coating composition having improved durability of plating.

In addition, according to the method for producing a primer coating composition applied to the chromium-coated surface of the present invention, it is possible to provide a primer coating composition which is applied to a chromium-coated surface that simplifies the manufacturing method and reduces the manufacturing cost by omitting one step of the manufacturing method There is an effect of providing a manufacturing method.

1 is a flow chart of a method of manufacturing a primer coating composition applied to a chromium-coated surface according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

In the automobile industry, efforts are being made to improve the quality of automotive parts in order to meet the demands of the customers who purchase the vehicles. Among them, exterior parts of vehicles are chrome-plated to improve corrosion resistance, durability and high-grade.

Generally, chromium plating can be classified into hexavalent chromium plating and trivalent chromium plating. The trivalent chrome plating is high in color and has excellent resistance to sludge build-up, but it has a high manufacturing cost and is limited in application to general parts. Accordingly, in order to solve the above problems, the present invention applies hexavalent chromium plating. In order to achieve the effect of trivalent chrome plating with hexavalent chrome plating, it is possible to obtain the effect of reducing the cost by implementing a two-layered coating on the hexavalent chromium plating to realize the high quality of trivalent chrome plating. Specifically, in the present invention, the construction of the coating is composed of two layers of a primer layer and a clear layer, and the primer layer plays a role of enhancing adhesion with the chromium plating layer. The adhesion with the chromium plating layer can be enhanced, and durability such as water resistance, moisture resistance, heat resistance, and chipping resistance can be improved. In the case of the chromium-plated high-gloss paint, there is a problem in that it can be visually confirmed even with small foreign objects or scratches due to the light coming from the plating. The above problem is solved by applying a general semi-transparent clear.

The present invention relates to a primer coating composition applied to a chromium-coated surface and a method for producing the primer coating composition, and, in one aspect, relates to a primer coating composition applied to a chromium-coated surface.

The primer coating composition applied to the chromium-coated surface of the present invention is a chromium-coated surface coating applied to a chromium-coated surface that maintains a pleasant metallic feel and maintains adhesion to the plating layer while providing various colors in a gentle manner The present invention relates to a primer coating composition, in which a pigment is added to a primer coating composition of the prior art, thereby omitting a base coat for color implementation. Furthermore, Clear coat used general exterior semi reflective clear.

More specifically, the present invention provides a primer coating composition which is applied to a chromium-free surface coated with a chromium base, which comprises a polyester resin, an adhesion promoter, a reaction catalyst, an organic pigment-dispersed colorant, a wetting additive and a solvent. In the present invention, the polyester resin is 40 to 70% by weight, the adhesion promoter is 2 to 5% by weight, the reaction catalyst is 0.1 to 1.5% by weight, the organic pigment dispersion colorant is 0.1 to 2.0% By weight, the wetting additive is 0.5 to 2.0% by weight, the solvent is 20 to 40% by weight, and the polyester resin has a solid content of 50% by weight of the total weight of the polyester resin and an average molecular weight of 20,000 To 40,000, and the content of hydroxyl groups is preferably 0.1 to 1.0%. In addition, the polyester resin may be one of trimellitic acid, trimellitic acid anhydride, pyromellitic dianhydride, trimethylol propane, glycerol, pentaerythritol, citric acid, tartaric acid and 3-hydroxyglutaric acid And the polyester resin is preferably selected from the group consisting of trimellitic anhydride, pyromellitic anhydride, glycerol, sorbitol, 1,2,6-hexanetriol, pentaerythritol, trimethylolethane and It is preferred that the polyfunctional monomer residues of at least one of the trimesic acids are included. In addition, the adhesion-promoting agent is preferably glycidoxy-functional epoxy methoxysilane, and the reaction catalyst is preferably dibutyltin dilaurate. The wetting agent is preferably a polydimethylsiloxane-based solvent, and the solvent is preferably a mixture of one or more selected from the group consisting of esters and hydrocarbons. In addition, it is preferable that the organic / inorganic pigment-dispersed colorant is dispersed at a nanometer size of 150 to 300 nm, further comprising a hexamethylene diisocyanate trimer system as a curing agent, and a weight ratio of the subject and the curing agent is preferably 10: 1 .

More specifically, the polyester resin has a solid content of 50%, a weight average molecular weight of 20,000 to 40,000 and a hydroxyl group content of 0.1 to 1.0%, and is crosslinked with isocyanate as a curing agent to form a coating film having good elasticity. That is, the polyester resin has a weight average molecular weight of 20,000 to 40,000, a hydroxyl group content of 0.1 to 1.0%, and a solid content of 50% by weight. Further, in order to produce a polyfunctional polyester resin, one or more polyfunctional (specifically, 3 to 4 functional groups) monomers must be contained. Further, examples of polyfunctional monomers include polyfunctional acids or glycols such as trimellitic acid, trimellitic anhydride, pyromellitic dianhydride, trimethylolpropane, glycerol, pentaerythritol, citric acid, tartaric acid , 3-hydroxyglutaric acid, and the like. In addition, the polyfunctional monomer residues can be at least one of trimellitic anhydride, pyromellitic anhydride, glycerol, sorbitol, 1,2,6-hexanetriol, pentaerythritol, trimethylolethane, and trimesic acid But is not limited thereto.

Further, the adhesion promoter is preferably a glycidoxy (epoxy) functional methoxy silane, preferably 2 to 5 wt%. If the adhesion promoter is less than 2% by weight, the effect is insufficient. If the adhesion promoter is more than 5% by weight, haze is caused.

In addition, the reaction catalyst may be a urethane reaction catalyst and may improve the reaction rate of the subject (hydroxyl group) and the curing agent (isocyanate), and it is preferably 0.1 to 1.5% by weight. If the amount of the reaction catalyst is less than 0.1% by weight, the reaction rate is slowed. If the amount of the catalyst is more than 1.5% by weight, the working time is shortened and the workability is deteriorated.

Also, the organic or inorganic pigment-dispersed colorant plays a role of realizing various colors while maintaining a plating feeling by using a pigment dispersed in nano size, and the nano size is 150 to 300 nm, preferably 0.1 to 2.0 wt% Do. When the amount of the organic or inorganic pigment-dispersed coloring agent is less than 0.1% by weight, the coloring effect is small. When the amount is more than 2% by weight, the plating layer is concealed.

In addition, the wetting additive is a polydimethylsiloxane-based additive, which improves the wettability and the leveling property of the coating film. The wet additive is preferably 0.5 to 2.0 wt%. If the amount of the wetting additive is less than 0.5 wt%, the leveling property is insufficient, and when the wetting additive is more than 2 wt%, the interlayer adhesion is deteriorated.

In addition, the solvent facilitates the coating operation and ensures the smoothness and appearance of the coating film by controlling the volatilization rate of the solvent. The solvent is preferably at least one selected from the group consisting of an ester series and a hydrocarbon series. The content may vary depending on the required thickness of the coating film and the coating film forming method, but it is preferably 20 to 40% by weight.

Further, it is preferable that the curing agent is a hexamethylene diisocyanate trimer system having excellent non-yellowing and weathering properties.

The present invention relates to a primer coating composition applied to a chromium-coated surface and a method for producing the primer coating composition, and, in one aspect, relates to a method for preparing a primer coating composition applied to a chromium-coated surface.

Specifically, a mixing step (S101) in which a primer coating composition applied to a chromium-coated surface of the present invention is introduced into a reactor and mixed therewith; An ester reaction step (S103) in which the mixed primer coating composition is ester-reacted; And a polyester condensation reaction step (S105) in which the ester-reacted primer coating composition becomes a polyester condensation reaction. The present invention also provides a method for producing a primer coating composition. In the present invention, it is preferable that the reactor is maintained at 200 to 230 ° C in the mixing step (S101), and the ester condensation by-product of low molecular weight is removed in the ester reaction step (S103). Further, in the ester reaction step (S103), it is preferable that the ester reaction is terminated based on the point of time when the conversion rate of the ester reaction is at least 95% of the total outflow amount of the low molecular weight ester by-product, and the polyester condensation reaction step S105 ), The reactor is preferably maintained at 250 to 280 ° C. The polyester condensation reaction step (S105) preferably stops the reaction at an acid value of 2 to 4 KOH / g.

More specifically, FIG. 1 is a flowchart of a method of manufacturing a primer coating composition applied to a chromium-coated surface according to an embodiment of the present invention. First, components of a primer coating composition to be applied to the chromium-coated surface of the present invention are added to a reactor equipped with a stirrer and mixed. While maintaining the temperature of the reactor at 200 to 230 ° C, the ester condensation by- Wherein the conversion of the ester reaction is terminated based on the point at which at least 95% of the total effluent of the low molecular weight ester by-product is drained. When the ester reaction is terminated, the polyester condensation reaction is induced while raising the reactor temperature to 250 to 280 ° C. The polyester condensation reaction is allowed to proceed and the reaction is stopped at an acid value of 2 to 4 mg KOH / g to prepare a primer coating composition to be applied to the chromium-coated surface of the present invention.

Further, it is preferable that the coating and curing method is such that the weight ratio of the top-curing agent is 10: 1 and the coating viscosity is about 13.0 to 15.0 sec by using a diluting solvent.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

One embodiment of the present invention relates to a polyester resin composition comprising G0-2104 (self resin -NRB) as a polyester resin, DOW CORNING Z-6040 Silane as an adhesion promoter, dibutyltin dilaurate as a reaction catalyst, S4 series (NRB Colorant), BYK-306 as a wetting additive and a solvent, and HI-100 (BASF) as a curing agent.

The comparative example was prepared as follows. The low molecular weight polyester resin used in Comparative Example 1 had a weight average molecular weight of 8,000 to 12,000, a hydroxyl group content of 1.0 to 2.0% and a solid content of 50% by weight. In the production process of the present invention, the synthesis was carried out by controlling the molecular weight in the same manner. To make a polyfunctional polyester resin, one or more polyfunctional (3- to 4-functional) monomers must be included. Examples of polyfunctional monomers include polyfunctional acids or glycols such as trimellitic acid, trimellitic acid anhydride, pyromellitic dianhydride, trimethylolpropane, glycerol, pentaerythritol, citric acid, tartaric acid, 3 -Hydroxyglutaric acid, and the like. Preferably, the polyfunctional monomer residues are selected from the group consisting of trimellitic anhydride, pyromellitic anhydride, glycerol, sorbitol, 1,2,6-hexanetriol, pentaerythritol, trimethylolethane, and trimesic acid And the polyester resin was prepared in the following manner. First, an acid component, a polyhydric alcohol component, a catalyst and various additives are added to a reactor equipped with a stirrer, ester condensation by-products of low molecular weight are removed while the temperature of the reactor is maintained at 200 to 230 ° C, , The conversion of this ester reaction is terminated based on the time point at which at least 95% of the total effluent of the low molecular weight ester by-product is drained. When the ester reaction is terminated, the polyester condensation reaction is induced while raising the reactor temperature to 250 to 280 ° C. The polyester condensation reaction proceeded and the reaction was stopped at an acid value of 2 to 4 mg KOH / g.

On the other hand, the high molecular weight acrylic resin used in Comparative Example 2 had a weight average molecular weight of 25,000 to 40,000, no hydroxyl groups participating in the reaction, and a solid content of 50% by weight. The high molecular weight acrylic resin composition is prepared by radical polymerization of various kinds of monomers having vinyl type double bonds of acrylic acid ester or methacrylic acid ester in solution using a thermal decomposition initiator. The larger the molecular weight, the better the adhesion to the metal. However, when the weight average molecular weight is 40,000 or more, the use of the resin in paints is limited to the limit of coating workability. The high molecular weight non-reactive acrylic resin can be prepared by the following method. First, a solvent such as toluene, xylene, or ketones is introduced into a four-necked flask equipped with a stirrer, a condenser and a thermometer, and while maintaining the temperature of the reactor at 100 to 130 DEG C, a methacrylic monomer, The monomer and the initiator are added dropwise to the solvent at a temperature of 100 ° C to 130 ° C for 2 hours to 5 hours. After the completion of the dropwise addition, the additional initiator is diluted with the solvent for 0.5 to 1 hour and then dropped for 0.5 to 1 hour. After the addition of the additional initiator, the mixture was maintained at the same temperature for 2 to 3 hours and then cooled and packed to prepare a high molecular weight acrylic resin having a weight average molecular weight of 25,000 to 40,000, no hydroxyl groups participating in the reaction, and a solid content of 50% .

Further, Comparative Examples 3 to 5 were produced by the production method of the present invention, but there are differences as shown in Table 1 below.

division Composition (% by weight) Hardener
(weight%) High molecular weight polyester resin Low molecular weight polyester resin High molecular weight acrylic resin Adhesion promoter Reaction catalyst Organic and inorganic pigment dispersion colorant Wet additive solvent Sum Comparative Example 1 - 60 - 4 1.0 1.5 1.0 32.5 100 10 Comparative Example 2 - - 60 4 1.0 1.5 1.0 3.25 100 10 Comparative Example 3 60 - - 0 1.0 1.5 1.0 36.5 100 10 Comparative Example 4 60 - - 1.8 1.0 1.5 1.0 34.7 100 10 Comparative Example 5 60 - - 5.2 1.0 1.5 1.0 31.3 100 10 Example 1 60 - - 2.2 1.0 1.5 1.0 34.3 100 10 Example 2 60 - - 4.8 1.0 1.5 1.0 31.7 100 10 Example 3 60 - - 4 1.0 1.5 1.0 32.5 100 10

The results are shown in Table 1 after coating with the coating composition according to the composition shown in Table 1 above. Appearance evaluation was evaluated for visible discernible defects such as discoloration, gloss drop, sagging orange peel. The initial adhesive property was evaluated by drawing a perforation line with a cutter so as to reach the surface of the coated film, making 100 square boxes each having a size of 2 mm x 2 mm, adhering them to the surface with adhesive cellophane tape, The residual coating film number was evaluated. For the heat resistance, the test piece was left in a chamber at a test temperature of 90 ± 2 ° C for 300 hours, and then subjected to external appearance evaluation and initial adhesion test. The water resistance was evaluated by the external appearance test and the initial adhesion test after leaving the test piece for 240 hours in the constant temperature water bath under the condition of the temperature of 40 ± 2 ° C. The moisture resistance was evaluated by the external appearance evaluation and the initial adhesion test after leaving the test piece for 240 hours in a chamber having a test temperature of 50 ± 2 ° C. and a relative humidity of 95 ± 2% RH. The chipping resistance was measured by using a gravimetric tester (GRAVELOMETER: SAEJ 400 standard product), dialyzed, air blown to remove surface foreign matter, and then the chipped surface was observed. At this time, Were evaluated as 'good', 4 ~ 10 as 'normal', and 10 or more as 'bad'. The results of the above evaluation are shown in Table 2 below.

division Exterior Initial adhesion Heat resistance Water resistance Moisture resistance Endothelial Comparative Example 1 Good 61/100 55/100 0/100 11/100 24 Comparative Example 2 Good 100/100 100/100 0/100 64/100 18 Comparative Example 3 Good 100/100 100/100 66/100 89/100 13 Comparative Example 4 Good 100/100 100/100 70/100 90/100 10 Comparative Example 5 Bad 100/100 Bad 84/100 89/100 12 Example 1 Good 100/100 100/100 100/100 100/100 6 Example 2 Good 100/100 100/100 100/100 100/100 3 Example 3 Good 100/100 100/100 100/100 100/100 3

As shown in Table 2, Comparative Example 1 did not satisfy initial adhesion, heat resistance, water resistance, moisture resistance and chipping resistance. In addition, Comparative Examples 2 to 4 did not satisfy the water resistance and moisture resistance. Further, Comparative Example 5 did not satisfy the appearance, heat resistance, water resistance, moisture resistance and chipping resistance. However, it can be confirmed that Examples 1 to 3 satisfied all the conditions.

The present invention has the effect of improving the parts performance, improving the convenience, simplifying the process and reducing the cost by including the organic pigment-dispersed colorant in the primer coating composition. More specifically, the use of nano-dispersed pigments enables a variety of designs to be realized by overcoming the deterioration of physical properties according to the depth of chrome plating conventionally, achieving a beautiful and delicate color while maintaining the metallic feel of chrome plating by designing a high- Depending on the type of pigment added to the primer, it is possible to implement various colors desired by consumers (blue, brown, gray, etc.). In addition, the present invention can realize various colors desired by simply adjusting the paint by changing the color by the plating method, and it is possible to realize the color which is the role of the base by implementing the primer so that the existing primer, a base coat and a clear coat can be simplified to a two-layer coating process. In addition, the present invention has the effect of reducing cost due to the implementation of a desired color with a two-layer coating as compared to the color implementation according to the plating method. In addition, it can be coated with hexavalent chrome plating, so that a trivalent chromium plating effect can be obtained.

Although the present invention has been described in connection with the specific embodiments of the present invention, it is to be understood that the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Various modifications and variations are possible.

S101: Mixing step
S103: ester reaction step
S105: Polyester polymerization step

Claims (17)

The primer coating composition according to any one of claims 1 to 3, wherein the primer coating composition comprises a polyester resin, an adhesion promoter, a reaction catalyst, an organic pigment-dispersed colorant, a wetting additive and a solvent.
The method according to claim 1,
Wherein the adhesion promoter is from 2 to 5% by weight, the reaction catalyst is from 0.1 to 1.5% by weight, the organic pigment-dispersed colorant is from 0.1 to 2.0% by weight, Wherein the additive is 0.5 to 2.0 wt%, and the solvent is 20 to 40 wt%.
3. The method of claim 2,
Wherein the polyester resin has a solid content of 50 wt% of the total weight of the polyester resin, an average molecular weight of 20,000 to 40,000, and a hydroxyl group content of 0.1 to 1.0%. .
The method of claim 3,
The polyester resin is at least one of trimellitic acid, trimellitic acid anhydride, pyromellitic dianhydride, trimethylol propane, glycerol, pentaerythritol, citric acid, tartaric acid and 3-hydroxyglutaric acid Wherein the primer coating composition is applied to a chromium-coated surface.
5. The method of claim 4,
The polyester resin may comprise at least one polyfunctional monomer residue selected from trimellitic anhydride, pyromellitic anhydride, glycerol, sorbitol, 1,2,6-hexanetriol, pentaerythritol, trimethylolethane and trimesic acid Wherein the primer coating composition is applied to a chromium-coated surface.
3. The method of claim 2,
Wherein the adhesion promoter is glycidoxy epoxy functional methoxy silane.
3. The method of claim 2,
Wherein the reaction catalyst is dibutyltin dilaurate. ≪ RTI ID = 0.0 > 11. < / RTI >
3. The method of claim 2,
Wherein the wetting additive is a polydimethylsiloxane-based primer coating composition applied to a chromium-coated surface.
3. The method of claim 2,
Wherein the solvent is one or more selected from the group consisting of esters and hydrocarbons.
3. The method of claim 2,
Wherein the organic / inorganic pigment-dispersed colorant is dispersed at a nanometer size of 150 to 300 nm.
3. The method of claim 2,
And a hexamethylene diisocyanate trimer system as a curing agent, wherein the weight ratio of the subject to the curing agent is 10: 1.
Mixing a primer coating composition applied to a chromium-coated surface of any one of claims 1 to 11 into a reactor and mixing the same;
An ester reaction step in which the mixed primer coating composition is ester-reacted; And
And a polyester condensation reaction step in which the ester-reacted primer coating composition becomes a polyester condensation reaction.
13. The method of claim 12,
Wherein the mixing step is carried out at a temperature of 200 to 230 DEG C in the reactor.
13. The method of claim 12,
Wherein the ester reaction step is carried out on a chromium-coated surface characterized in that low-molecular weight ester condensation by-products are removed.
13. The method of claim 12,
Wherein the ester reaction step is carried out on a chromium-coated surface, wherein the esterification reaction is terminated based on a point of time at which 95% or more of the esterification reaction conversion rate of the low molecular weight ester by-product outflows out.
13. The method of claim 12,
Wherein the polyester condensation reaction step is carried out at a temperature of 250 to 280 ° C.
13. The method of claim 12,
Wherein the polyester condensation reaction step is stopped at an acid value of 2 to 4 KOH / g.

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