KR20210039746A - Primer coat composition - Google Patents

Abstract

The present invention relates to a primer coating composition, which contains an acrylic polyol resin, a first polyester resin, a second polyester resin, a cellulose resin and a melamine resin, wherein the first polyester resin has a higher hydroxyl value and a lower glass transition temperature than the second polyester resin. The present invention relates to the primer coating composition having excellent metal texture and capable of forming a coating film having a luxurious appearance.

Description

Primer coating composition {PRIMER COAT COMPOSITION}

The present invention relates to a primer coating composition having excellent metallic texture and capable of forming a coating film having a luxurious appearance.

A conventional automobile roof rack is composed of a bar made of aluminum, a cover made of plastic, and a stent that is combined with a vehicle body and serves as a support. The aluminum bar is usually coated with acrylic or powder for baking, and the cover and the stent of the plastic material are typically subjected to low-temperature curing urethane coating. As described above, when different types of coating were applied to different materials, a problem occurred in that the color of the manufactured automobile roof rack was different. In particular, in the case of high-brightness silver coating, the color of the coating film manufactured according to the type of the paint and the coating method is very different, and thus, when coating different systems as described above, there is a limitation in that it is difficult to implement a coating film of the same color.

In this regard, Japanese Patent No. 3,863,367 (Patent Document 1) discloses a coating composition comprising a modified vinyl-based copolymer containing a quaternary ammonium base, a polyester resin, and an acrylic resin.

Meanwhile, for the purpose of reducing vehicle weight, an integrated roof rack bar and cover made of a plastic material has been recently developed. For this reason, it has become possible to paint a high-brightness silver coating film, which has been increasing in demand from the market, on an integral roof rack made of a plastic material. However, the conventional roof rack coating composition has a limitation in that it must be dried at a high temperature while the metallic feel is lowered.

Accordingly, there is a need for research and development on a primer coating composition capable of forming a coating film having a high luminance silver color, which is a metallic texture, and excellent in various physical properties such as adhesion, water resistance, and weather resistance.

Japanese Patent Registration No. 3,863,367 (published on May 9, 2002)

Accordingly, the present invention provides a primer coating composition capable of forming a coating film having a high luminance silver color, which is a metallic texture, and excellent in various physical properties such as adhesion, water resistance, and weather resistance.

The present invention includes an acrylic polyol resin, a first polyester resin, a second polyester resin, a cellulose resin and a melamine resin,

The first polyester resin provides a primer coating composition having a higher hydroxyl value and a lower glass transition temperature than the second polyester resin.

The primer coating composition according to the present invention has excellent coating workability and excellent adhesion to plastic materials. In addition, the coating film prepared from the primer coating composition has high luminance and excellent metal texture, so that it has luxurious appearance characteristics, and is excellent in water resistance and weather resistance.

Hereinafter, the present invention will be described in detail.

As used herein, "weight average molecular weight" is measured by a conventional method known in the art, for example, it can be measured by a gel permeation chromatograph (GPC) method. Further, the "glass transition temperature" is measured by a conventional method known in the art, for example, it can be measured by differential scanning calorimetry (DSC). In addition, functional groups such as "acid value" and "hydroxyl value" may be measured by methods well known in the art, and may represent values measured by, for example, titration.

In addition, in the present specification, “(meth)acrylic” means “acrylic” and/or “methacrylic”, and “(meth)acrylate” means “acrylate” and/or “methacrylate” .

The primer coating composition according to the present invention includes an acrylic polyol resin, a first polyester resin, a second polyester resin, a cellulose resin, and a melamine resin.

Acrylic polyol resin

The acrylic polyol resin serves to improve the workability of the composition.

The acrylic polyol resin may be directly synthesized according to a known method, or a commercially available product may be used. In this case, the acrylic resin may be prepared by polymerizing at least one of a vinyl group-containing monomer and a hydroxyl group-containing (meth)acrylate monomer.

The type of the vinyl group-containing monomer is not particularly limited, but, for example, styrene, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, or a mixture thereof Can be used.

The hydroxyl group-containing (meth)acrylate monomer is, for example, 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2- Hydroxybutyl (meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di( It is possible to use meth)acrylates or mixtures thereof.

In addition, the acrylic polyol resin may have a hydroxyl value (Ohv) of 50 to 80 mgKOH/g, or 60 to 70 mgKOH/g. When the hydroxyl value of the acrylic polyol resin is within the above range, there is an effect of improving chemical resistance.

The acrylic polyol resin may have a glass transition temperature (Tg) of 10 to 70°C, or 30 to 50°C. When the glass transition temperature of the acrylic polyol resin is within the above range, there is an effect of improving the hardness of the coating film.

The acrylic polyol resin may have a weight average molecular weight (Mw) of 15,000 to 25,000 g/mol, or 18,000 to 21,000 g/mol. When the weight average molecular weight of the acrylic polyol resin is within the above range, there is an effect of improving chemical resistance.

In addition, the acrylic polyol resin may be included in the composition in an amount of 5 to 30 parts by weight, or 10 to 20 parts by weight based on 5 to 25 parts by weight of the first polyester resin. When the content of the acrylic polyol resin is within the above range, it is possible to prevent a problem in that the coating workability of the composition is insufficient or the weather resistance of the prepared coating film is insufficient.

First polyester resin

The first polyester resin serves to improve adhesion to the material and physical properties of the manufactured coating film.

The first polyester resin may be directly synthesized according to a known method, or a commercially available product may be used. For example, the first polyester resin may be a polymer produced by a condensation reaction between a glycol monomer and a carboxyl group-containing monomer. Examples of the glycol monomer include neopentyl glycol, trimethylolpropane, diethylene glycol, triethylene glycol, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexane amitanol, and mixtures thereof. In addition, examples of the carboxyl group-containing monomer include terephthalic acid, maleic anhydride, fumaric acid, phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, adipic acid, and mixtures thereof.

The first polyester resin may have a higher hydroxyl value and a lower glass transition temperature than the second polyester resin. For example, the first polyester resin may have a hydroxyl value of 1.10 to 1.18 times greater than that of the second polyester resin and a glass transition temperature of 20 to 60°C lower than that of the second polyester resin. As described above, a composition containing two types of polyester resins having different hydroxyl values and glass transition temperatures has excellent appearance characteristics due to high brightness of the prepared coating film, and excellent adhesion to materials, water resistance, and weather resistance. .

The first polyester resin may have a hydroxyl value (Ohv) of 120 to 160 mgKOH/g, or 130 to 150 mgKOH/g. When the hydroxyl value of the first polyester resin is within the above range, there is an effect of improving water resistance.

The first polyester resin may have a glass transition temperature (Tg) of -30 to -10 °C, or -25 to -15 °C. When the glass transition temperature of the first polyester resin is within the above range, there is an effect of improving workability.

The first polyester resin may have a weight average molecular weight (Mw) of 5,000 to 15,000 g/mol, or 8,000 to 12,000 g/mol. When the weight average molecular weight of the first polyester resin is within the above range, there is an effect of improving adhesion.

In addition, the first polyester resin may be included in the composition in an amount of 5 to 25 parts by weight, or 11 to 20 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. When the content of the first polyester resin is within the above range, it is possible to prevent a problem of insufficient appearance characteristics or insufficient hardness of the manufactured coating film.

2nd polyester resin

The second polyester resin serves to improve the coating workability of the composition and the appearance characteristics of the produced coating film.

The second polyester resin may be directly synthesized according to a known method, or a commercially available product may be used. For example, the second polyester resin may be a polymer produced by a condensation reaction between a glycol monomer and a carboxyl group-containing monomer. Examples of the glycol monomer include neopentyl glycol, trimethylolpropane, diethylene glycol, triethylene glycol, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexane amitanol, and mixtures thereof. In addition, examples of the carboxyl group-containing monomer include terephthalic acid, maleic anhydride, fumaric acid, phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, adipic acid, and mixtures thereof.

The second polyester resin may have a hydroxyl value (Ohv) of 100 to 140 mgKOH/g, or 110 to 130 mgKOH/g. When the hydroxyl value of the second polyester resin is within the above range, there is an effect of improving water resistance.

The second polyester resin may have a glass transition temperature (Tg) of 10 to 30°C, or 15 to 25°C. When the glass transition temperature of the second polyester resin is within the above range, there is an effect of improving the hardness of the coating film.

The second polyester resin may have a weight average molecular weight (Mw) of 4,000 to 12,000 g/mol, or 6,000 to 9,000 g/mol. When the weight average molecular weight of the second polyester resin is within the above range, there is an effect of improving adhesion.

The weight ratio of the first polyester resin and the second polyester resin may be 1: 0.3 to 3, or 1: 0.6 to 1.8. When the weight ratio of the first polyester resin and the second polyester resin satisfies the above range, adhesion may be excellent.

In addition, the second polyester resin may be included in the composition in an amount of 10 to 25 parts by weight, or 10 to 20 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. When the content of the second polyester resin is within the above range, a problem of insufficient adhesion of the produced coating film and a problem of insufficient appearance characteristics of the base coating film formed on the primer coating film due to slow drying of the coating film may be prevented.

Cellulose resin

Cellulose resin is a polymer resin that quickly dries the coating film after painting. In this case, the cellulose resin may be a cellulose acetate butyrate (CAB) resin. The cellulose acetate butyrate resin refers to a cellulose derivative obtained by partial acetylation and butyl esterification of cellulose.

The cellulose resin may have a weight average molecular weight (Mw) of 80,000 to 200,000 g/mol or 100,000 to 140,000 g/mol. When the weight average molecular weight of the cellulose resin is within the above range, there is an effect of improving the workability of the composition.

The cellulose resin may have a viscosity of 100 to 150 KU, or 125 to 135 KU at 25° C., and the solid content may be 20 to 40% by weight, or 28 to 33% by weight. When the viscosity and solid content of the cellulose resin are within the above range, there is an effect of improving the workability of the composition.

In addition, the type of the cellulose acetate butyrate resin is not particularly limited as long as it is usually included in the primer coating composition, and directly synthesized according to a known method or a commercially available product may be used.

The weight ratio of the acrylic resin and the cellulose acetate butyrate resin may be 0.5 to 3:1, or 0.7 to 1.3:1. When the weight ratio of the acrylic resin and the cellulose acetate butyrate resin satisfies the above range, luminance may be excellent.

The cellulose acetate butyrate resin may be included in the composition in an amount of 4 to 20 parts by weight, or 10 to 16 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. When the content of the cellulose acetate butyrate resin is within the above range, there is an effect of improving workability of painting.

Melamine resin

Melamine resin may act as a curing agent in the composition.

The melamine resin may be directly synthesized according to a known method, or a commercially available product may be used. For example, the melamine resin may include a butoxy-methoxy mixed melamine resin, a methylate melamine resin, a butoxy melamine resin, and a methoxy melamine resin. Specifically, the melamine resin may be a hexamethoxymethyl melamine resin (hexamethoxymethyl melamine resin, HMMM resin).

The melamine resin may have a weight average molecular weight (Mw) of 100 to 1,000 g/mol, or 200 to 500 g/mol, and a degree of methylation of 80 to 90%. When the weight average molecular weight and methylation degree of the melamine resin are within the above ranges, the workability of the composition may be increased.

The melamine resin may have a Gardner viscosity at 25° C. of W to Z4, or X to Z2, and a solid content of 90 to 100% by weight. When the viscosity of the melamine resin is within the above range, the workability of the composition may be increased.

In addition, the melamine resin may be included in the composition in an amount of 5 to 20 parts by weight, or 7 to 12 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. If the content of the melamine resin is within the range, it is possible to prevent a problem in that the appearance characteristics of the prepared coating film are deteriorated or physical properties such as water resistance are deteriorated.

Urethane resin

The primer coating composition may further include a urethane resin.

The urethane resin serves to improve the adhesion of the coating film as an auxiliary resin.

The urethane resin may be directly synthesized according to a known method, or a commercially available product may be used. For example, the urethane resin may be prepared by reacting an alcohol compound and an isocyanate compound.

The alcohol compound may be a polyol containing two or more hydroxyl groups in one molecule, and examples thereof include polyester polyol, polyethylene polyol, polypropylene polyol, polybutylene polyol, and acrylic polyol.

The isocyanate compound may be a compound containing two or more isocyanate groups in one molecule, for example, isophorone diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, propylene di Isocyanate, ethylene diisocyanate, 2,3-dimethylethylene diisocyanate, 1-methyl trimethylene diisocyanate, 1,3-cyclopentene diisocyanate, 1,4-cyclopentene diisocyanate, 1,2-cyclopentene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, oligomeric isocyanate, isophorone diisocyanate, 4,4-diphenylpropane diisocyanate, Xylene diisocyanate, and 1,1,6,6-tetramethylhexamethylene diisocyanate, etc. are mentioned.

The urethane resin may have a weight average molecular weight (Mw) of 500 to 3,000 g/mol, or 1,000 to 2,500 g/mol. When the weight average molecular weight of the urethane resin is within the above range, there is an effect of improving the adhesion of the coating film.

The viscosity of the urethane resin at 25° C. may be 100 to 300 cps, or 130 to 170 cps. When the viscosity of the urethane resin is within the above range, the workability of the composition may be increased.

In addition, the urethane resin may be included in the composition in an amount of 5 to 20 parts by weight, or 7 to 15 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. When the content of the urethane resin is within a range, there is an effect of improving the adhesion of the coating film.

solvent

The primer coating composition may further include a solvent. At this time, the solvent serves to maintain the thickness of the coating film and improve the coating workability of the composition.

The type of the solvent is not particularly limited as long as it is usually used in the primer coating composition, and examples thereof include non-polar solvents such as n-heptane, toluene, xylene, petroleum compounds, and n-hexane; Butyl cellulose acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monoethyl ether acetate, dibasic ester, 3-methoxy butyl acetate, amyl acetate, butyl glycol acetate, methyl ethyl ketone, methyl isobutyl ketone, Polar solvents such as acetone, diisobutyl ketone, isophorone, n-butanol and cyclohexanone; And at least one of the mixture of the non-polar solvent and the polar solvent may be appropriately selected and used according to the characteristics of the resin or the volatilization rate. Specifically, the solvent may include an ester-based solvent and an ether-based solvent.

There is no particular limitation on the amount of the solvent used, but if too much of the solvent is used, a problem of lowering the adhesion or durability of the manufactured coating film may occur, and if too little is used, it is difficult to expect an effect due to the use of the solvent. For example, the solvent may be included in an amount of 10 to 30 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin.

Pigment

The primer coating composition may further include a pigment. The pigment serves to impart color to the prepared coating film. In this case, the pigment may be, for example, a color pigment, an extender pigment, or a mixture thereof.

The colored pigment serves to secure hiding power and impart color to the coating film. In this case, the colored pigment may be a black pigment, a white pigment, or a mixture thereof. The colored pigment may include pigments such as blue, red, yellow, and violet.

The extender pigment serves to increase the strength of the prepared coating film. As the extender pigment, any commonly known component may be used without particular limitation, and for example, talc, calcium carbonate, barium sulfate, calcium silicate, silica, or a mixture thereof may be used.

In addition, the pigment may be included in the composition in an amount of 5 to 15 parts by weight, or 10 to 15 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. When the pigment content in the primer composition is within the above range, it is possible to prevent the problem of insufficient hiding power of the prepared film and the problem of lowering the adhesion of the coating film.

additive

The primer coating composition may further include one or more additives selected from the group consisting of a surface modifier, a curing accelerator, and an ultraviolet absorber.

The additive may be included in the composition in an amount of 0.1 to 12 parts by weight, or 0.1 to 5 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin.

The surface modifier serves to control the surface tension of the paint. In this case, the type of the surface modifier is not particularly limited as long as it is generally used in the coating composition, and examples thereof include polysiloxane-based surface modifiers and non-silicone-based surface modifiers. In addition, the surface modifier may be included in the composition in an amount of 0.1 to 1.0 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. When the content of the surface modifier is less than 0.1 part by weight, the appearance characteristics of the prepared coating film may be deteriorated, and when it exceeds 1.0 part by weight, the recoating adhesion may be deteriorated.

The curing accelerator serves to shorten the drying speed and curing time of the coating film by accelerating the reaction between the polyol and the melamine resin in the composition. Examples of the curing accelerator include tetramethyl butane diamine, bicyclooctane, dibutyltin dilaurate, and triethylene diamine. At this time, the curing accelerator may be included in the composition in an amount of 0.01 to 1.0 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. When the content of the curing accelerator is less than 0.01 parts by weight, drying properties and coating properties of the composition may be deteriorated, and when it exceeds 1.0 parts by weight, the appearance properties of the prepared coating film and working time may be shortened, resulting in insufficient workability. .

The ultraviolet absorber has a stronger UV absorbing ability than the chromophore of the acrylic polyol resin, and thus inhibits the generation of radicals of the acrylic polyol resin, and serves to prevent discoloration, swelling, delamination, and loss of gloss of the acrylic polyol resin. The ultraviolet absorber may be, for example, a benzotriazole-based ultraviolet absorber, and specifically, may be hydroxyphenyl benzotriazole. In this case, the ultraviolet absorber may be included in the composition in an amount of 1 to 10 parts by weight based on 5 to 30 parts by weight of the acrylic polyol resin. When the content of the ultraviolet absorber exceeds 10 parts by weight, a problem of cost increase may occur, and when the content of the ultraviolet absorber is less than 1 part by weight, the weather resistance of the manufactured coating film may be lowered.

Acid catalyst

The primer coating composition according to the present invention may further include an acid catalyst. At this time, the acid catalyst serves to accelerate the reaction between the polyol in the primer coating composition and the melamine resin to speed up the curing speed of the composition.

The acid catalyst is, for example, dinonylnaphthalene disulfonic acid (DNNDSA), dinonylnaphthalene sulfonic acid (Dinonylnaphthalene (Mono) Sulfonic Acid, DNNSA), para-toluenesulfonic acid (p-Toluenesulfonic acid, PTSA), etc. Can be lifted.

For example, the primer coating composition may include a first component including an acrylic polyol resin, a first polyester resin, a second polyester resin, a cellulose resin, and a melamine resin; And a second component including an acid catalyst. In addition, the first component may further include a urethane resin, a solvent, a pigment and an additive.

In this case, the primer coating composition may include the first component and the second component in a weight ratio of 8:1 to 12:1. When the weight ratio of the first component and the second component satisfies the above range, coating properties such as adhesion and water resistance may be excellent.

The primer coating composition has a Pod Cup viscosity of 10 to 20 seconds, or 12 to 15 seconds based on Pod Cup No. 4 at 25° C., and 25 to 45% by weight, or 30 to 38% by weight based on the total weight of the composition. It may contain solids.

The primer coating composition according to the present invention as described above is excellent in painting workability, and excellent adhesion to plastic materials, particularly nylon materials, and swelling properties. In addition, the coating film prepared from the primer coating composition has high luminance and excellent metal texture, so that it has luxurious appearance characteristics, and is excellent in water resistance and weather resistance. In addition, the primer coating composition is suitable as a primer for automobile plastic parts because it has excellent material concealment after painting and has an appropriate drying rate.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for helping understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[Example]

Examples 1 to 7 and Comparative Examples 1 to 4. Preparation of primer coating composition

The first component was prepared by mixing each component in the composition as shown in Table 1 below. Thereafter, para-toluene sulfonic acid as an acid catalyst was mixed with the first component in a weight ratio of 10:1 to prepare a primer coating composition. After that, it was diluted with thinner and the viscosity of No. 4 Pod Cup was adjusted to 13 to 14 seconds at 25°C.

division
(Part by weight) Example Comparative example One 2 3 4 5 6 7 One 2 3 4 1-1 polyester resin 20 12 18 15 13 - - - 24.5 25 20.5 Section 1-2 polyester resin - - - - - 20 13 - - - - 2-1 polyester resin 18 19 11 19 13 - - 23 - 20 25 2-2 polyester resin - - - - - 18 13 - - - - 1st acrylic polyol resin 11 18 13 10 15 - - 13 15 - 13 Second acrylic polyol resin - - - - - 11 15 - - - - First CAB resin 14 14 16 12 14 - - 16 15 16 - 2nd CAB resin - - - - - 14 14 - - - - Urethane resin - - - - 8 - 8 - - - - First melamine resin 7.5 7.5 10 12 7.5 - - 9 9.5 9 9.5 2nd melamine resin - - - - - 7.5 7.5 - - - - Pigment 11 11 13 11 11 11 11 13 12 11 13 solvent 18 18 18.5 20.5 18 18 18 25 23 18 18 Surface modifier 0.5 0.5 0.5 0.5 0.5 0.5 0.5 One One One One total 100 100 100 100 100 100 100 100 100 100 100

Examples 8 to 12 and Comparative Examples 5 and 6. Preparation of primer coating composition

A first component was prepared by mixing each component in a composition as shown in Table 2 below. Thereafter, para-toluene sulfonic acid as an acid catalyst was mixed with the first component in a weight ratio of 8:1 to prepare a primer coating composition. After that, it was diluted with thinner and the viscosity of No. 4 Pod Cup was adjusted to 13 to 14 seconds at 25°C.

Classification (parts by weight) Example Comparative example 8 9 10 11 12 5 6 1-1 polyester resin 20 12 13 - - - 24.5 Section 1-2 polyester resin - - - 20 13 - - 2-1 polyester resin 18 19 13 - - 23 - 2-2 polyester resin - - - 18 13 - - 1st acrylic polyol resin 11 18 15 - - 13 15 Second acrylic polyol resin - - - 11 15 - - First CAB resin 14 14 14 - - 16 15 2nd CAB resin - - - 14 14 - - Urethane resin - - 8 - 8 - - First melamine resin 7.5 7.5 7.5 - - 9 9.5 2nd melamine resin - - - 7.5 7.5 - - Pigment 11 11 11 11 11 13 12 solvent 18 18 18 18 18 25 23 Surface modifier 0.5 0.5 0.5 0.5 0.5 One One total 100 100 100 100 100 100 100

Examples 13 to 17 and Comparative Examples 7 and 8. Preparation of primer coating composition

The first component was prepared by mixing each component in the composition as shown in Table 3 below. Thereafter, the first component was mixed with p-toluene sulfonic acid as an acid catalyst in a weight ratio of 12:1 to prepare a primer coating composition. After that, it was diluted with thinner and the viscosity of No. 4 Pod Cup was adjusted to 13 to 14 seconds at 25°C.

Classification (parts by weight) Example Comparative example 13 14 15 16 17 7 8 1-1 polyester resin 12 18 13 - - 25 20.5 Section 1-2 polyester resin - - - 20 13 - - 2-1 polyester resin 19 11 13 - - 20 25 2-2 polyester resin - - - 18 13 - - 1st acrylic polyol resin 18 13 15 - - - 13 Second acrylic polyol resin - - - 11 15 - - First CAB resin 14 16 14 - - 16 - 2nd CAB resin - - - 14 14 - - Urethane resin - - 8 - 8 - - First melamine resin 7.5 10 7.5 - - 9 9.5 2nd melamine resin - - - 7.5 7.5 - - Pigment 11 13 11 11 11 11 13 solvent 18 18.5 18 18 18 18 18 Surface modifier 0.5 0.5 0.5 0.5 0.5 One One total 100 100 100 100 100 100 100

Hereinafter, manufacturers and product names of each component used in Examples and Comparative Examples are shown below.

-1-1 polyester resin: solid content 80% by weight, Ohv 131mgKOH/g, Tg -25℃, Mw 8,050g/mol

-Part 1-2 polyester resin: solid content 80% by weight, Ohv 148mgKOH/g, Tg -15℃, Mw 11,500g/mol

-2-1 polyester resin: solid content 70% by weight, Ohv 112mgKOH/g, Tg 16℃, Mw 6,000g/mol

-2-2 polyester resin: solid content 70% by weight, Ohv 129mgKOH/g, Tg 23℃, Mw 8,800g/mol

-First acrylic polyol resin: 50% by weight of solid content, Ohv 60mgKOH/g, Tg 30℃, Mw 18,000g/mol

-Second acrylic polyol resin: 50% by weight of solid content, Ohv 70mgKOH/g, Tg 47℃, Mw 21,000g/mol

-First CAB resin: 28% by weight solid content, Mw 100,000g/mol, viscosity 125KU at 25°C

-Second CAB resin: solid content 33% by weight, Mw 140,000g/mol, viscosity 135KU at 25℃

-Urethane resin: Mw 1,900g/mol, viscosity at 25°C 150cps, NCO% 0% by weight

-First melamine resin: solid content 97% by weight, Mw 300g/mol, methylation degree 83%, Gardner viscosity X at 25°C

-Second melamine resin: solid content 97% by weight, Mw 500g/mol, methylation degree 88%, Gardner viscosity Z2 at 25°C

-Pigment: a mixture of titanium dioxide and carbon black in a weight ratio of 10:1.

-Solvent: a mixture of toluene, butyl cellulose acetate and n-butanol in a weight ratio of 10:2:1

-Surface modifier: BYK306 (manufactured by BYK, polysiloxane-based surface modifier)

Test Example: Evaluation of the properties of the manufactured coating film

The primer coating compositions of Examples and Comparative Examples were coated on a material made of nylon to a dry coating thickness of 17±2 μm, and allowed to stand at room temperature for 5 minutes to form a primer coating.

Thereafter, the base paint (manufacturer: KCC, product name: UT5800) was applied to a dry film thickness of 5±2 μm, and hot air was blown at 80° C. for 30 minutes to cure to form a final coat. The appearance characteristics and physical properties of the final coating film were measured by the following method, and the results are shown in Table 4.

(1) adhesion

According to the ASTM D3359 tape adhesion test method, the adhesion of the final coating film was drawn into 100 squares (1 mm width x 1 mm length) with a blade, and peeled off using a tape to measure the adhesion.

At this time, if 100 squares are 100% fully attached, it is excellent (◎), if the remaining squares are 95% or more and less than 100%, it is good (○), if it is 90% or more and less than 95%, it is normal (△), and it is 85% or more and less than 90%. The case was evaluated as defective (×).

(2) luminance

The Flop Index (FI) value was measured with a luminance meter (manufacturer: X-RITE, model name: MA-98), and it was determined that the higher the FI value, the better the sense of brightness.

(3) water resistance

After immersing the final coating film in a 40℃ thermostat for 10 days, the adhesion of the coating film was evaluated. The evaluation criteria are excellent (◎) when 100% of the 100 squares are completely attached, and good when more than 95% and less than 100% are attached ( ○), if 90% or more and less than 95% were attached, it was evaluated as normal (△), and if less than 90% was attached, it was evaluated as defective (×).

(4) Weather resistance

After exposing the final coating with energy of 2,500 kJ in the environment of the xenon weatherometer tester, the appearance, color difference, and adhesion of the coating film before and after energy exposure were compared.Color difference △E 3.0 or less, adhesion M 1.0 to 2.5, gray scale 3 Grade or higher is excellent (◎), color difference △E exceeds 3.0, adhesiveness is M 1.0 to 2.5, and gray scale grade 3 or higher is good (○), If the color difference △E is more than 3.0 and the adhesion is M 1.0 to 2.5 and the gray scale is less than 3 grade, it is evaluated as normal (△), and the color difference △E is more than 3.0 and the adhesion is more than M 2.5 and is less than 3 grades is evaluated as defective (×). I did. At this time, the M value is a value evaluated according to the adhesion evaluation criteria described in ISO 2409, and the gray scale was evaluated according to the regulations prescribed in KSK 0910.

(5) Painting workability

The primer coating compositions of Examples and Comparative Examples were coated twice reciprocally using IWATA 61 on a 30cm×40cm (width×length) tin plate to compare the degree of atomization, smoothness, and paint film peelability during coating.

Specifically, excellent (◎) when the surface has good spreadability within the surface with the naked eye and excellent (◎), good when the surface is good, but lacks the spreadability by the naked eye (○), and is insufficient with the naked eye. If the painting foreign body occurred with less than 3 points, it was evaluated as normal (△), and when the painting foreign body was more than 3 points and cratering occurred, it was evaluated as defective (×).

Adherence Luminance Water resistance Weather resistance Painting workability Example One ◎ 21 ◎ ◎ ◎ 2 ◎ 24 ◎ ◎ ◎ 3 ◎ 22 ◎ ◎ ◎ 4 ◎ 22 ◎ ◎ ◎ 5 ◎ 23 ◎ ◎ ◎ 6 ◎ 24 ○ ◎ ○ 7 ◎ 23 ◎ ○ ○ 8 ◎ 21 ◎ ◎ ○ 9 ◎ 22 ◎ ◎ ○ 10 ◎ 23 ◎ ◎ ○ 11 ◎ 21 ○ ◎ ○ 12 ◎ 22 ◎ ○ ○ 13 ◎ 22 ◎ ◎ ○ 14 ◎ 21 ◎ ◎ ○ 15 ◎ 21 ◎ ◎ ○ 16 ◎ 22 ○ ◎ ○ 17 ◎ 23 ◎ ○ ○ Comparative example One X 21 ○ ○ △ 2 ○ 20 △ ○ X 3 ○ 18 ○ △ X 4 △ 9 ○ ○ △ 5 X 20 △ ○ ○ 6 ○ 20 △ ○ X 7 ○ 18 ○ △ X 8 △ 9 ○ ○ ○

As shown in Table 4, the primer coating compositions of Examples 1 to 17 have excellent coating workability, and the coating film prepared therefrom has excellent adhesion, water resistance, and weather resistance, and has a high luminance value of 21 or more, so that the metal texture is excellent. It was excellent.

On the other hand, the coating films prepared from the primer coating compositions of Comparative Examples 1 to 8 lacked adhesion, water resistance and/or weather resistance, or lack of coating workability.

Claims (6)

Including an acrylic polyol resin, a first polyester resin, a second polyester resin, a cellulose resin and a melamine resin,
The first polyester resin has a higher hydroxyl value and a lower glass transition temperature than the second polyester resin, primer coating composition. The method according to claim 1,
The acrylic polyol resin has a hydroxyl value of 50 to 80 mgKOH/g, and a glass transition temperature of 10 to 70° C., a primer coating composition. The method according to claim 1,
The first polyester resin has a hydroxyl value of 120 to 160 mgKOH/g, a glass transition temperature of -30 to -10 °C,
The second polyester resin has a hydroxyl value of 100 to 140 mgKOH/g and a glass transition temperature of 10 to 30° C., a primer coating composition. The method according to claim 1,
The melamine resin has a Gardner viscosity at 25° C. of W to Z4, and a weight average molecular weight of 100 to 1,000 g/mol, a primer coating composition. The method according to claim 1,
The composition further comprises a urethane resin,
The urethane resin has a weight average molecular weight of 500 to 3,000 g/mol, a primer coating composition. The method according to claim 1,
The primer coating composition includes 5 to 30 parts by weight of an acrylic polyol resin, 5 to 25 parts by weight of a first polyester resin, 10 to 25 parts by weight of a second polyester resin, 4 to 20 parts by weight of a cellulose resin, and 5 to 20 parts by weight of melamine. A primer coating composition containing a resin.