KR20210043375A - Base coating composition - Google Patents

Abstract

The present invention relates to a base coating composition comprising an acrylic resin and a cellulose-based resin, wherein the acrylic resin has a glass transition temperature of 30 to 70℃ and a weight average molecular weight of 10,000 to 40,000 g/mol. The present invention provides the base coating composition which has excellent coating workability, and in which a coating layer formed by using the composition has excellent appearance characteristics, adhesion properties, water resistance and weather resistance.

Description

Base coating composition {BASE COATING COMPOSITION}

The present invention relates to a base coating composition which is coated on a trivalent chromium plated surface to form a coating film having excellent appearance characteristics, adhesion, water resistance, weather resistance, and the like.

In the case of plastic parts applied to automobiles, it is common to perform pretreatment, primer coating, base coat and clear coat coating in order to improve the appearance properties and protect the surface from the external environment. At this time, the base coat composition generally includes a thermosetting resin such as polyester, acrylic, urethane resin, and the like as a main resin.

In this regard, Korean Patent Application Publication No. 2015-0071907 (Patent Document 1) includes a primer composition comprising a polyester resin; And an acrylic polyol resin, a cellulose acetate butyrate resin, and a topcoat composition comprising a resin selected from polyethylene and polyethylene-propylene copolymer; a two-component non-ferrous metal coating agent is disclosed. However, as in Patent Literature 1, the conventional base coat composition containing a thermosetting resin has a limitation in forming a coating film having a poor appearance quality compared to a vehicle body. Accordingly, there is an increasing demand for improvement of the appearance quality of plastic parts for automobiles.

Accordingly, there is a need for research and development on a base coat composition having excellent appearance characteristics, adhesion, water resistance and weather resistance of the produced coating film, and excellent coating workability.

Korean Patent Application Publication No. 2015-0071907 (published date: 2015.6.29.)

Accordingly, the present invention provides a base coat composition having excellent appearance characteristics, adhesion, water resistance and weather resistance of the produced coating film, and excellent coating workability.

The present invention includes an acrylic resin and a cellulose-based resin,

The acrylic resin provides a base coating composition having a glass transition temperature of 30 to 70° C. and a weight average molecular weight of 10,000 to 40,000 g/mol.

The base coat composition according to the present invention has excellent coating workability, and the coating film prepared therefrom is excellent in appearance characteristics, adhesion, water resistance, heat resistance, acid resistance and weather resistance, and thus can be usefully used to paint automobile parts.

Hereinafter, the present invention will be described in detail.

As used herein, "weight average molecular weight" and "number average molecular weight" are measured by a conventional method known in the art, and can be measured, for example, 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, the term "parts by weight" as used herein means a weight ratio between raw material components.

The base coating composition according to the present invention includes an acrylic resin and a cellulose resin.

Acrylic resin

Acrylic resin plays a role in implementing high-pressure washability and chipping resistance of the coating film.

The acrylic resin is not particularly limited as long as it can be included in the base coating composition in general, and directly synthesized according to a known method may be used, or a commercially available product may be used. For example, the acrylic resin may be prepared by polymerizing at least one selected from the group consisting of vinyl monomers and (meth)acrylate monomers. In this case, the "(meth)acrylate" means "acrylate" and/or "methacrylate".

The vinyl monomer is not particularly limited in its kind, but, for example, styrene, methylstyrene, dimethylstyrene, fluorostyrene, ethoxystyrene, methoxystyrene, phenylene vinyl ketone, vinyl t-butyl benzoate, vinyl cyclo At least one selected from the group consisting of hexanoate, vinyl acetate, vinyl pyrrolidone, vinyl chloride, vinyl alcohol, acetoxystyrene, t-butylstyrene, and vinyltoluene.

The type of the (meth)acrylate monomer is not particularly limited, but, for example, N-methylolacrylamide, 2-hydroxypropyl methacrylate, propyl methacrylate, t-butylaminoethyl methacrylate, Dicyclopentenyl oxyethyl methacrylate, acrylic acid dimer, hexanediol diacrylate, t-butyl acrylate, triisopropylsilyl acrylate, benzyl methacrylate, hydroxyethyl methacrylate phthalate, 2-hydroxyethyl Methacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, ethyl methacrylate, diacetone acrylamide, isobutyl methacrylate, hydroxyisopropyl methacrylate, isopropyl methacrylate, cyclohexyl Methacrylate, triisopropyl silyl methacrylate, isobornyl acrylate, t-butylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, acrylonitrile, methyl methacrylate, acrylic acid, t-butyl methacrylate , Isobornyl methacrylate, methacrylonitrile, methacrylic acid, acrylamide, methacrylamide, chlorostyrene, and one or more selected from the group consisting of cyclohexyl vinyl ether.

In addition, the acrylic resin may have an acid value (Av) of 1 to 15 mgKOH/g, or 1 to 10 mgKOH/g. When the acid value of the acrylic resin is within the above range, the adhesion and appearance of the prepared coating film may be excellent. On the other hand, when the acid value of the acrylic resin is out of the above range, the hardness and appearance of the prepared coating film may be deteriorated due to a delay in the curing reaction of the composition.

The acrylic resin may have a glass transition temperature (Tg) of 30 to 70°C, or 35 to 55°C. When the glass transition temperature of the acrylic resin is within the above range, workability of the composition and water resistance and adhesion of the prepared coating film may be excellent.

The acrylic resin may have a weight average molecular weight (Mw) of 10,000 to 40,000 g/mol, or 13,500 to 28,000 g/mol. When the weight average molecular weight of the acrylic resin is within the above range, weather resistance and chipping resistance of the prepared coating film may be excellent.

The acrylic resin may have a hydroxyl value (Ohv) of 30 to 180 mgKOH/g, or 35 to 165 mgKOH/g. When the hydroxyl value of the acrylic resin is within the above range, the hardness and appearance of the prepared coating film may be excellent.

The acrylic resin may be included in the composition in an amount of 10 to 50 parts by weight, or 20 to 40 parts by weight based on 5 to 40 parts by weight of the cellulose-based resin. When the content of the acrylic resin is within the above range, physical properties such as moisture resistance and heat resistance of the prepared coating film may be excellent.

Cellulose resin

Cellulose-based resin plays a role in imparting the appearance, adhesion, coating workability, and dispersibility of the coating film.

The cellulose-based resin serves to uniformly disperse the pigment and realize the metallic texture of the coating film when forming the coating film, and serves to improve the adhesion performance to the base material by acting as a binder in the composition.

The cellulose-based resin may include at least one selected from the group consisting of a nitrocellulose (NC) resin and a cellulose acetate butyrate (CAB) resin.

At this time, the nitrocellulose resin is a resin in which hydrogen (H) of the hydroxy group (OH) of cellulose _{is substituted with a nitric oxide (NO 2} ), and is not particularly limited as long as it can be included in the base coating composition. Directly synthesized according to the method described, or commercially available products may be used. For example, the nitrocellulose resin may be prepared by dissolving cellulose in a mixture of sulfuric acid and nitric acid, or by mixing cellulose dissolved in nitric acid with a solvent such as water.

The nitrocellulose resin may contain 5 to 20% by weight, or 10 to 13% by weight of nitrogen based on the total weight of the resin. When the nitrogen content of the nitrocellulose resin is within the above range, there is an effect of improving the dispersibility, acid resistance, and alkali resistance of the composition.

The nitrocellulose resin may have a number average molecular weight (Mn) of 20,000 to 120,000 g/mol, and a solid content (NV) of 20 to 40% by weight, or 25 to 35% by weight. When the weight average molecular weight of the nitrocellulose resin is within the above range, the prepared coating film may exhibit high luminance, and heat cycle resistance may be excellent.

In addition, the nitrocellulose resin may be included in the composition in an amount of 0 to 40 parts by weight, or 0 to 35 parts by weight based on 10 to 50 parts by weight of the acrylic resin. When the content of the nitrocellulose resin is within the above range, the appearance characteristics of the prepared coating film may be excellent.

The cellulose acetate butyrate (CAB) resin refers to a cellulose derivative obtained by partial acetylation and butyl esterification of cellulose, and is not particularly limited as long as it can be included in the base coating composition, and is synthesized directly according to a known method. It can be used, or a commercially available product can be used.

The cellulose acetate butyrate resin may have an acetyl group content of 1 to 20% by weight, or 1.5 to 15.5% by weight, and a butyl group content of 25 to 60% by weight, or 33 to 53% by weight, based on the total weight of the cellulose acetate butyrate resin. Can be When the content of the acetyl group and the butyl group of the cellulose acetate butyrate resin is within the above range, high luminance may be realized.

The cellulose acetate butyrate resin may have a glass transition temperature (Tg) of 60 to 180°C or 85 to 161°C. When the glass transition temperature of the cellulose acetate butyrate resin is within the above range, moisture resistance may be excellent.

The cellulose acetate butyrate resin may have a weight average molecular weight (Mw) of 10,000 to 80,000 g/mol, or 12,000 to 70,000 g/mol. When the weight average molecular weight of the cellulose acetate butyrate resin is within the above range, high luminance may be realized, and coating properties such as heat resistance and acid resistance may be excellent.

In addition, the cellulose acetate butyrate resin may be included in the composition in an amount of 0 to 40 parts by weight, or 0 to 35 parts by weight based on 10 to 50 parts by weight of the acrylic resin. When the content of the cellulose acetate butyrate resin is within the above range, the appearance characteristics of the prepared coating film may be excellent.

The cellulose-based resin may be included in the composition in an amount of 5 to 40 parts by weight, or 10 to 35 parts by weight based on 10 to 50 parts by weight of the acrylic resin. When the content of the additional resin is within the above range, the appearance is excellent and there is an effect of imparting painting workability.

The weight ratio of the acrylic resin and the cellulose-based resin may be 1: 0.2 to 3, or 1: 0.25 to 1.75. When the weight ratio of the acrylic resin and the cellulose-based resin is within the above range, the appearance of the coating film, acid resistance, and alkali resistance may be excellent.

Polyester resin

The base coating composition may further include a polyester resin. At this time, the polyester resin serves to impart coating workability.

The polyester resin is not particularly limited as long as it can be included in the base coating composition in general, and may be directly synthesized according to a known method, or a commercially available product may be used. For example, the polyester resin can be prepared by reacting a carboxylic acid and a polyol.

At this time, the carboxylic acid is adipic acid (AA), isophthalic acid (IPA), trimalic anhydride (TMA), alicyclic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, fumaric acid, maleic anhydride, It may be one or more selected from the group consisting of tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and derivatives thereof. In addition, the polyol is methoxypolyethylene glycol, 1,6-hexanediol (1,6-HD), neopentyl glycol (NPG), trimethylol propane (TMP), ethylene glycol, propylene glycol, diethylene glycol, butanediol 1 It may be one or more selected from the group consisting of, 4-hexanediol and 3-methylpentanediol.

The polyester resin may have an acid value (Av) of 1 to 20 mgKOH/g, or 2 to 10 mgKOH/g. When the acid value of the polyester resin is out of the above range, the curing reaction of the composition may be delayed and thus the hardness and appearance of the prepared coating film may be deteriorated.

The polyester resin may have a number average molecular weight (Mn) of 650 to 2,300 g/mol, or 1,000 to 1,800 g/mol. When the number average molecular weight of the polyester resin is within the above range, there is an excellent effect of chipping resistance of the manufactured coating film, and when it is out of the above range, the chipping resistance, water resistance, and adhesion of the manufactured coating film may be deteriorated.

The polyester resin may have a glass transition temperature (Tg) of -30 to 30°C, or -20 to 20°C. When the glass transition temperature of the polyester resin is within the above range, the workability of the composition and the water resistance of the manufactured coating film may be improved, and when the glass transition temperature is outside the above range, the weather resistance of the manufactured coating film may be lowered. .

In addition, the polyester resin may have a Gardner viscosity at 25° C. of W to Z6, or Y to Z4. When the viscosity at 25° C. of the polyester resin is within the above range, adhesion and chipping resistance of the prepared coating film may be improved, and when the viscosity of the polyester resin is out of the above range, the chipping resistance of the prepared coating film may be lowered.

The polyester resin may be included in the composition in an amount of 0 to 30 parts by weight, or 0 to 15 parts by weight based on 10 to 50 parts by weight of the acrylic resin. When the content of the polyester resin is within the above range, there is an effect of excellent coating workability.

Pigment

The composition may further include a pigment in order to impart color or increase strength to the prepared coating film.

The pigment may be, for example, a color pigment, an extender pigment, a pearl 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, a blue pigment, a red pigment, a yellow pigment, a violet pigment, or a mixture thereof.

At this time, the black pigment may be used without particular limitation as long as it is a commonly known black pigment, and for example, carbon black, graphite, iron oxide, or a mixture thereof may be used. In addition, as the white pigment, if it is a commonly known white pigment, it may be used without particular limitation, and for example, titanium dioxide or the like may be used.

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.

The pearl pigment serves to impart a metallic feel to the prepared coating film. The pearl pigment may be used without particular limitation as long as it is a commonly known component, and examples thereof include aluminum paste, mika, and the like.

In this case, the pigment may be included in the composition in an amount of 3 to 20 parts by weight, or 5 to 15 parts by weight based on 10 to 50 parts by weight of the acrylic resin. When the content of the pigment is within the above range, a problem in that the appearance of the manufactured coating film is deteriorated or the strength is decreased, and a problem in which the chipping resistance and high-pressure washing property of the manufactured coating film are deteriorated can be prevented.

solvent

The composition may further include a solvent in order to increase the viscosity and dispersibility of the composition and to secure workability. At this time, the solvent may be, for example, an aromatic hydrocarbon-based solvent, an ether-based solvent, or a mixture thereof.

The aromatic hydrocarbon-based solvent may be, for example, xylene, toluene, or a mixture thereof. In addition, as a commercial item of the aromatic hydrocarbon-based solvent, cocosol #100, cocosol #150, and the like may be mentioned.

In addition, the ether solvent is, for example, di-n-butyl ether, di-isobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, Di-tert-amyl ether, di-n-hexyl ether, methylcyclopentyl ether, methylcyclohexyl ether, methylphenyl ether, methylbenzyl ether, ethylcyclopentyl ether, ethylcyclohexyl ether, ethylphenyl ether, ethylbenzyl ether, or these It may be a mixture of.

The solvent may be included in the composition in an amount of 10 to 45 parts by weight, or 15 to 40 parts by weight based on 10 to 50 parts by weight of the acrylic resin. When the content of the solvent is within the above range, it is possible to prevent problems in which viscosity control of the composition is difficult or dispersibility is deteriorated, and a problem in that the appearance of the manufactured coating film is deteriorated or a long time is consumed in forming the coating film.

additive

The base coating composition according to the present invention may further include one or more additives selected from the group consisting of a thickener and a hardening accelerator.

The thickener serves to control the viscosity of the base paint composition. The thickener may be used without particular limitation as long as it is a commonly known component, and for example, fumed silica, organo clay, wax, urea, or a mixture thereof may be used. In addition, the thickener may be included in the composition in an amount of 0.1 to 5 parts by weight, or 0.5 to 4 parts by weight based on 10 to 50 parts by weight of the acrylic resin.

The curing accelerator serves to increase the curing reactivity of the base coating composition. The curing accelerator may be used without particular limitation as long as it is a commonly known component. For example, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin bis (acetylacetonate), dibutyltin oxide, Dibutyltin maleate, dibutyltin octoate, dibutyltin dimaleate or mixtures thereof may be used. In addition, the curing accelerator may be included in the composition in an amount of 0.1 to 5 parts by weight, or 0.5 to 3 parts by weight based on 10 to 50 parts by weight of the acrylic resin.

The base coating composition according to the present invention as described above has excellent coating workability, and the coating film produced therefrom has excellent appearance characteristics, adhesion, water resistance, heat resistance, acid resistance, and weather resistance, and thus automobile parts (e.g., radiator grille , Door handles, handles, center fascia, gearbox, etc.).

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only intended to aid 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 15 and Comparative Examples 1 to 7. Preparation of base coating composition

A base coating composition was prepared using the contents of each component shown in Tables 1 to 3.

Ingredients (parts by weight) Example One 2 3 4 5 6 7 Acrylic resin 1 20 30 20 - 30 23 27 Acrylic resin 2 - - 10 - - - - Acrylic resin 3 - - - 20 - - - Polyester resin1 10 - 10 10 - 4 - Polyester resin2 - 10 - - - - 15 Polyester resin4 - - - - 10 - - CAB resin 1 20 - 20 20 - 23 - CAB resin 2 - 20 - - 20 - 18 Metallic pigment 6 6 6 6 6 6 6 Black pigment 6 6 6 6 6 6 6 Hardening accelerator One One One One One One One Thickener One One One One One One One Solvent 1 16 16 16 16 16 16 16 Solvent 2 20 10 10 20 10 20 10 total 100 100 100 100 100 100 100

Ingredients (parts by weight) Example 8 9 10 11 12 13 14 15 Acrylic resin 1 24 22 - - - - - - Acrylic resin 2 - - 40 20 40 20 40 - Acrylic resin 3 - - - 20 - 20 - 40 Polyester resin3 13 - - - - - - - Polyester resin4 - 8 - - - - - - CAB resin 1 10 - - - - - - - CAB resin 2 - 31 - - - - - - NC resin 1 - - 30 30 - - 20 - NC resin 2 - - - - 30 30 - 10 Metallic pigment 6 6 6 6 6 6 6 6 Black pigment 6 6 2 2 2 2 2 2 Hardening accelerator One One One One One One One One Thickener One One 3 3 3 3 3 3 Solvent 1 17 15 8 8 8 8 13 16 Solvent 2 22 10 10 10 10 10 15 22 total 100 100 100 100 100 100 100 100

Ingredients (parts by weight) Comparative example One 2 3 4 5 6 7 Acrylic resin 1 - 60 - - - - - Acrylic resin 4 - - - 20 - - - Acrylic resin 5 - - - - 30 - - Acrylic resin 6 - - - - - 40 - Acrylic resin 7 - - - - - - 40 Polyester resin1 10 - - 11 - - - CAB resin 1 41 - - 20 20 - - NC resin 1 - - 70 - - 30 30 Metallic pigment 6 6 6 6 6 6 6 Black pigment 5 5 One 5 5 One One Hardening accelerator One One One One One One One Thickener One One 3 One 2 3 3 Solvent 1 16 16 8 16 16 8 8 Solvent 2 20 11 11 20 20 11 11 total 100 100 100 100 100 100 100

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

-Acrylic resin 1: Av 2mgKOH/g, Ohv 38mgKOH/g, Tg 53℃, Mw 26,800g/mol

-Acrylic resin 2: Av 1.2mgKOH/g, Ohv 155mgKOH/g, Tg 50℃, Mw 14,000g/mol

-Acrylic resin 3: Av 7 mgKOH/g, Ohv 139 mgKOH/g, Tg 39℃, Mw 17,500g/mol

-Acrylic resin 4: Av 5 mgKOH/g, Ohv 100 mgKOH/g, Tg 26℃, Mw 20,000g/mol

-Acrylic resin 5: Av 3mgKOH/g, Ohv 85mgKOH/g, Tg 74℃, Mw 23,800g/mol

-Acrylic resin 6: Av 4.6mgKOH/g, Ohv 121mgKOH/g, Tg 42℃, Mw 8,100g/mol

-Acrylic resin 7: Av 6.2mgKOH/g, Ohv 141mgKOH/g, Tg 49℃, Mw 43,200g/mol

-Polyester resin 1: Av 3mgKOH/g, Tg -20℃, Mn 1,050g/mol, Gardner viscosity Z3 at 25℃

-Polyester resin 2: Av 7mgKOH/g, Tg 17℃, Mn 1,500g/mol, Gardner viscosity Z at 25℃

-Polyester resin 3: Av 8mgKOH/g, Tg -15℃, Mn 1,300g/mol, Gardner viscosity Z2 at 25℃

-Polyester resin 4: Av 10mgKOH/g, Tg 5℃, Mn 1,800g/mol, Gardner viscosity Y at 25℃

-Cellulose acetate butyrate (CAB) resin 1: acetyl group content 2% by weight, butyl group content 52% by weight, Tg 85 ℃, Mw 70,000 g/mol

-Cellulose acetate butyrate (CAB) resin 2: acetyl group content 15.5 wt%, butyl group content 35 wt%, Tg 141°C, Mw 12,000 g/mol

-Nitrocellulose (NC) resin 1: nitrogen content 10% by weight, Mn 30,000g/mol, NV 30% by weight

-Nitrocellulose (NC) resin 2: nitrogen content 13% by weight, Mn 100,000g/mol, NV 30% by weight

-Metallic pigment: DECOMET 3504/10, SCHLENK METALLIC PIGMENTS GMBH

-Black Pigment: Carbon Black

-Thickener: AEROSIL R-972, EVONIK

-Curing accelerator: dibutyltin dilaurate

-Solvent 1: Toluene

-Solvent 2: Xylene

Experimental example. Evaluation of coating properties

The undercoat composition was coated on the plated surface (plated object: radiator grill) with trivalent chromium (dry coating thickness: 10-14 µm), and dried at room temperature for about 7 minutes to form a undercoating film. At this time, the primer coating composition is a mixture of the main coating material (manufacturer: KCC, product name: UU2721-AD/GREY) and a polyisocyanate-based curing agent (HDI Buiret type, manufacturer: COVESTRO, product name: ACU35541) in a weight ratio of 20:1 Then, it was prepared by diluting with a thinner so that the viscosity of Pod Cup #4 at 25° C. was 13 to 14 seconds.

Thereafter, the base coating compositions prepared in Examples 1 to 15 and Comparative Examples 1 to 7 were coated on the base coat (dry coat thickness: 20-30 μm), and dried at room temperature for 9 minutes to form a base coat.

Thereafter, the physical properties of the base coating film as described above were evaluated in the following manner, and the results are shown in Table 3 below. At this time, excellent is ◎, good is ○, usually △ and defective is indicated by X.

(1) Appearance

The degree of air bubbles, foreign matter, spots, grooves, and orange peel of the prepared coating film was evaluated visually. The test was repeated 6 times, and it was evaluated as excellent if it passed 6 times, as good if it passed 5 times, as normal if it passed 3 and 4 times, and as bad if it passed less than 3 times. At this time, the pass condition is that there are no air bubbles, foreign matter, spots, and grooves, and there is no orange peel visually.

(2) adhesion

The adhesion of the final coating film was evaluated for the number of peeled portions out of 100 scales of 1 mm×1 mm (width×length) according to the ASTM D3359 tape adhesion test method. The test was repeated 6 times, and it was evaluated as excellent if it passed 6 times, as good if it passed 5 times, as normal if it passed 3 and 4 times, and as bad if it passed less than 3 times. At this time, the passing conditions were M2.5 or higher for adhesion based on the standards described in ISO 2409.

(3) water resistance

After immersing the final coating film in a 40°C thermostat for 10 days, the evaluation of the adhesion and appearance of item (2) was conducted. The test was repeated 6 times, and it was excellent when it passed 6 times, and it was good when it passed 5 times. In the case of passing 3 and 4 times, it was evaluated as normal, and when it passed less than 3 times, it was evaluated as defective. At this time, the passing condition was that the adhesion was M2.5 or more and that the coating film had no external swelling, cracking, and discoloration, and it was visually determined.

(4) moisture resistance

The final coating film was allowed to stand for 10 days under conditions of 50±2° C. and 95±2% relative humidity, and then the final coating layer was removed by air blow. Thereafter, after allowing to stand at room temperature for 1 hour, the appearance and adhesion were evaluated, and the adhesion was performed in the same manner as in item (2). The test was repeated 6 times, and it was evaluated as excellent if it passed 6 times, as good if it passed 5 times, as normal if it passed 3 and 4 times, and as bad if it passed less than 3 times. At this time, the passing condition was that the adhesion was M2.5 or more and that the coating film had no external swelling, cracking, and discoloration, and it was visually determined.

(5) heat resistance

After the final coating was left in an oven at 80° C. for 300 hours, the adhesion and appearance were evaluated, and the adhesion was performed in the same manner as in item (2). The test was repeated 6 times, and it was evaluated as excellent if it passed 6 times, as good if it passed 5 times, as normal if it passed 3 and 4 times, and as bad if it passed less than 3 times. At this time, the passing condition was that the adhesion was M2.5 or more and that the coating film had no external swelling, cracking, and discoloration, and it was visually determined.

(6) Heat resistance cycle test

The final coating was treated at 80±2℃ for 3 hours, at room temperature for 1 hour, at -40±2℃ for 3 hours, at room temperature for 1 hour, 50±2℃ and relative humidity for 7 hours at 95±2%, And the treatment at room temperature for 1 hour was performed once, a total of 5 times were repeated heat treatment, and then allowed to stand at room temperature for 1 hour, and then the appearance and adhesion of the final coating film were evaluated. The adhesion was performed in the same manner as in item (2), and the test was repeated 6 times. Evaluation criteria were evaluated as excellent if passed 6 times, good if passed 5 times, normal if passed 3 and 4 times, and poor if passed less than 3 times. At this time, the passing condition was that the adhesion was M2.5 or more and that the coating film had no external swelling, cracking, and discoloration, and it was visually determined.

(7) Salt water spray resistance

The final coating was sprayed for 240 hours according to the spray conditions (35±2℃ and 95% relative humidity, spray volume: 0.5~3.0ml/h, saline solution concentration: 5±1w/v%, saline solution pH: 6.5~7.2). Then, it was washed with water and the moisture was removed. After leaving for 1 hour at room temperature, the appearance and adhesion of the coating film were evaluated. The adhesion was performed in the same manner as in item (2), and the test was repeated 6 times. Evaluation criteria were evaluated as excellent if passed 6 times, good if passed 5 times, normal if passed 3 and 4 times, and poor if passed less than 3 times. At this time, the passing condition was that the adhesion was M2.5 or more and that the coating film had no external swelling, cracking, and discoloration, and it was visually determined.

(8) acid resistance

After dropping 0.2 ml of 0.1N sulfuric acid aqueous solution on the surface of the final coating film, let it stand at room temperature for 24 hours, wash with water, remove moisture from the surface by air blow, and leave it at room temperature for 1 hour, and then change the appearance of the final coating film. It was observed to evaluate the acid resistance. The test was repeated 6 times, and it was evaluated as excellent if it passed 6 times, as good if it passed 5 times, as normal if it passed 3 and 4 times, and as bad if it passed less than 3 times. At this time, the pass condition was judged to have a gray scale (KSK 0910) of 3 or higher. At this time, as for the gray scale, it was determined that the grade 5 was no pollution, the grade 3 was normal, and the grade 2 was polluted.

(9) alkali resistance

Alkali resistance was evaluated in the same manner as in Item (8), except that 0.1N sodium hydroxide aqueous solution was used instead of the sulfuric acid aqueous solution.

(10) Weather resistance

After exposure to the energy of 2500 kJ in the environment of the xenon weatherometer tester, the appearance and adhesion of the coating film were evaluated. The adhesion was performed in the same manner as in item (2), and the test was repeated six times. Evaluation criteria were evaluated as excellent if passed 6 times, good if passed 5 times, normal if passed 3 and 4 times, and poor if passed less than 3 times. At this time, the passing condition was that the adhesion was M2.5 or more and that the coating film had no external swelling, cracking, and discoloration, and it was visually determined.

(11) High pressure car wash

Using a high-pressure car wash tester, high-pressure water was sprayed onto the final coating film at a pressure of 70 kgf at a distance of 10 cm, and the degree of peeling of the coating film was evaluated. The test was repeated 6 times, and it was evaluated as excellent if it passed 6 times, as good if it passed 5 times, as normal if it passed 3 and 4 times, and as bad if it passed less than 3 times. At this time, the passing conditions were based on the adhesion of M2.5 or higher.

(12) chipping resistance

After firing 50 g of the stele at a distance of 100 mm from the final coating film at an angle of 45°, a pressure of 4.0 kgf and room temperature, the degree of occurrence of marks on the surface of the final coating film was evaluated. The test was repeated 6 times, and it was evaluated as excellent if it passed 6 times, as good if it passed 5 times, as normal if it passed 3 and 4 times, and as bad if it passed less than 3 times. At this time, the pass conditions were based on the occurrence of two or less marks of 2 mm or more on the surface of the final coating film.

ingredient Exterior Adherence Water resistance Moisture resistance Heat resistance Heat cycle resistance Salt water spray resistance Acid resistance Alkali resistance Weather resistance High pressure car wash Chipping resistance Example One ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 2 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 3 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 4 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 5 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 6 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 7 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 8 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 9 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 10 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 11 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 12 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 13 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 14 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ 15 ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ ◎ Comparative example One △ △ △ X X △ △ △ △ X △ △ 2 X △ △ △ △ △ △ X X △ △ △ 3 △ X X X X △ X △ △ △ △ △ 4 ○ X X △ ○ △ △ ○ ○ △ ○ ○ 5 ○ X X △ △ △ ○ ○ ○ △ ○ ○ 6 ○ ○ ○ △ △ ○ △ ○ ○ X ○ X 7 ○ ○ ○ ○ △ △ △ ○ ○ X ○ X

As shown in Table 4, the final coating films prepared from the compositions of Examples 1 to 15 are adhesion, moisture resistance, heat resistance, heat cycle resistance, salt spray resistance, acid resistance, alkali resistance, weather resistance, high pressure washability and chipping resistance. It was found that all of the physical properties of the back were excellent.

Claims (6)

Including an acrylic resin and a cellulose-based resin,
The acrylic resin has a glass transition temperature of 30 to 70° C. and a weight average molecular weight of 10,000 to 40,000 g/mol. The method according to claim 1,
The acrylic resin has an acid value of 1 to 15 mgKOH/g, and a hydroxyl value of 30 to 180 mgKOH/g, a base coating composition. The method according to claim 1,
The cellulose-based resin comprises at least one selected from the group consisting of a nitrocellulose resin and a cellulose acetate butyrate resin, a base coating composition. The method according to claim 1,
The composition comprises 10 to 50 parts by weight of an acrylic resin and 5 to 40 parts by weight of a cellulose-based resin. The method according to claim 1,
The composition further comprises a polyester resin, the base coating composition. The method of claim 5,
The polyester resin has an acid value of 1 to 20 mgKOH/g, a number average molecular weight of 650 to 2,300 g/mol, and a glass transition temperature of -30 to 30°C.