KR102266647B1 - Clear coat composition for refinishing automobiles - Google Patents

Abstract

The present invention relates to a first acrylic resin having a glass transition temperature of 70°C or higher and less than 100°C, a second acrylic resin having a glass transition temperature of 100°C or higher and 160°C or lower, and a third and fourth acrylic resin and polyester having a glass transition temperature of 10°C or lower. It relates to a transparent coating composition for automobile repair, comprising a resin, wherein the hydroxyl value of the third acrylic resin is lower than the hydroxyl value of the fourth acrylic resin.

Description

Transparent paint composition for automobile repair {CLEAR COAT COMPOSITION FOR REFINISHING AUTOMOBILES}

The present invention relates to a transparent coating composition for automobile repair capable of forming a coating film having excellent paintability, spreadability, pinhole resistance and hardness.

Efforts to shorten working hours and reduce heat treatment costs are continuing in order to gain competitiveness in the automobile repair and painting industry due to the large size of automobile maintenance companies and the integration and closure of small companies. For this reason, the economic feasibility of paint and work is being emphasized more in the automobile repair painting system. In particular, in the era of high oil prices, there is a demand for paints that can be completed quickly while consuming less energy in the automobile repair field.

Automobile repair is a process that restores a wide range of damaged areas to their original form, ranging from small local vehicle damage to large 3-panel damage repair. Recently, with the advancement of the exterior of automobiles, there is a trend of increasing partial repair and local area repair.

The automobile repair process for repairing damaged parts is largely divided into a surface adjustment stage, an intermediate process stage, and a topcoat process stage. The top coating process step is typically a step of masking a portion that does not require topcoating, a step of applying a color paint to match the color, a step of applying a transparent paint to impart gloss and increasing durability, and a light to finish the exterior surface of the painting cleanly including betting and evaluation stages, etc. In this case, as the transparent paint used in the topcoating process, a paint composition using various resins such as epoxy-based, urethane-based, sealant-based, and acrylic-based resins are used.

Specifically, Korean Patent Registration No. 1,826,058 (Patent Document 1) discloses an acrylic polyol resin synthesized using methyl methacrylate, isobornyl acrylate, butyl acrylate, hydroxyethyl methacrylate, and methacrylic acid; light stabilizer; UV absorbers; silicone surfactants; non-silicone surface active agents; urethane reaction accelerator; And a stain-resistant transparent coating composition comprising an organic solvent is disclosed. However, the transparent coating composition of Patent Document 1 has a limit in that scratch resistance is lowered.

Therefore, it is possible to form a coating film with excellent paintability, spreadability, pinhole resistance and hardness, and research and development of a transparent coating composition with low volatile organic solvent compound (VOC) content, high solid content, and fast drying speed, which is excellent in economic feasibility. it is necessary.

Korean Patent Registration No. 1,826,058 (published on June 30, 2014)

The present invention provides a transparent coating composition that can form a coating film with excellent paintability, spreadability, pinhole resistance and hardness, and has a low volatile organic solvent compound (VOC) content, high solid content, and fast drying speed, which is excellent in economical efficiency.

In order to achieve the above object, the present invention provides a first acrylic resin having a glass transition temperature of 70°C or more and less than 100°C, a second acrylic resin having a glass transition temperature of 100°C or more and 160°C or less, and a first acrylic resin having a glass transition temperature of 10°C or less. It provides a transparent coating composition for automobile repair, comprising a third and fourth acrylic resin and a polyester resin, wherein the hydroxyl value of the third acrylic resin is lower than the hydroxyl value of the fourth acrylic resin.

The transparent paint composition for automobile repair according to the present invention is economical due to its high solid content and fast drying rate, and is environmentally friendly due to its low VOC content. In addition, the coating film prepared from the transparent coating composition is excellent in paintability, spreadability, pinhole resistance and hardness.

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 GPC (gel permeation chromatograph) method. Furthermore, 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 a method well known in the art, for example, may represent a value measured by a method of titration.

A transparent paint composition for automobile repair according to the present invention includes a main part including a first acrylic resin, a second acrylic resin, a third acrylic resin, a fourth acrylic resin and a polyester resin, a solvent and an additive; and a curing agent unit; That is, the transparent coating composition may be a two-component coating composition including a main part and a curing agent part.

subject part

first acrylic resin

The first acrylic resin serves to improve the appearance characteristics, in particular, the gloss of the prepared coating film.

The first acrylic resin is not particularly limited as long as it can be included in the conventional transparent coating composition, and a product directly synthesized according to a known method or a commercially available product may be used. In this case, the first acrylic resin may be, for example, prepared by polymerizing at least one of a vinyl monomer and a (meth)acrylate monomer.

The type of the vinyl monomer is not particularly limited, but for example, styrene, methylstyrene, dimethylstyrene, fluorostyrene, ethoxystyrene, methoxystyrene, phenylene vinyl ketone, vinyl t-butyl benzoate, vinyl cyclohexano At least one selected from ester, vinyl acetate, vinyl pyrrolidone, vinyl chloride, vinyl alcohol, acetoxystyrene, t-butylstyrene and vinyltoluene may be used.

Examples of the (meth)acrylate monomer include 2-hydroxypropyl methacrylate, propyl methacrylate, t-butylaminoethyl methacrylate, dicyclopentenyl oxyethyl methacrylate, acrylic acid dimer, and hexanediol. diacrylate, t-butyl acrylate, triisopropylsilyl acrylate, benzyl methacrylate, 2-hydroxyethyl methacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, ethyl methacrylate, Isobutyl methacrylate, hydroxyisopropyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, triisopropyl silyl methacrylate, isobornyl acrylate, t-butylcyclohexyl methacrylate, trimethylcyclo hexyl methacrylate, methyl methacrylate, acrylic acid, t-butyl methacrylate, isobornyl methacrylate, methacrylonitrile, methacrylic acid, acrylamide, methacrylamide, chlorostyrene, cyclohexylvinylether One or more types may be used.

In this case, the first acrylic resin may have a glass transition temperature (Tg) of 70°C or more and less than 100°C, 70 to 90°C, or 80 to 90°C. When the glass transition temperature of the first acrylic resin is within the above range, there is an effect of improving hardness.

In addition, the first acrylic resin may have an acid value (Av) of 3 to 15 mgKOH/g, or 3 to 10 mgKOH/g. When the acid value of the first acrylic resin is within the above range, solubility and clarity are improved.

In addition, the first acrylic resin may have a hydroxyl value (Ohv) of 130 to 160 mgKOH/g, or 140 to 150 mgKOH/g. When the hydroxyl group of the first acrylic resin is within the above range, there is an effect that the sagging property is improved.

In addition, the first acrylic resin may have a weight average molecular weight (Mw) of 1,500 to 3,500 g/mol, or 2,000 to 3,000 g/mol. When the weight average molecular weight of the first acrylic resin is within the above range, there is a soft effect in chemical resistance and paint spraying feeling (spray feeling).

In addition, the first acrylic resin may have a solid content of 60 to 90% by weight, 65 to 85% by weight, or 70 to 80% by weight based on the total weight of the resin. When the solid content of the first acrylic resin is within the above range, high-solidification of the composition may be realized and paintability may be excellent.

The first acrylic resin may be included in the composition in an amount of 5 to 20 parts by weight, or 8 to 15 parts by weight based on 10 to 30 parts by weight of the second acrylic resin in the main part. When the first acrylic resin is included within the content range, compatibility is good.

2nd acrylic resin

The second acrylic resin serves to secure dryness of the composition and improve the smoothness of the prepared coating film.

The second acrylic resin may be directly synthesized in the same manner as described for the first acrylic resin, or a commercially available product may be used.

In this case, the second acrylic resin may have a glass transition temperature (Tg) of 100°C or more and 160°C or less, 120 to 150°C, or 130 to 140°C. When the glass transition temperature of the second acrylic resin is within the above range, there is an effect of imparting hardness and improving drying properties of the coating film.

In addition, the second acrylic resin may have an acid value (Av) of 5 to 30 mgKOH/g, 7 to 20 mgKOH/g, or 8 to 15 mgKOH/g. When the acid value of the second acrylic resin is within the above range, mixing stability with other resins is increased and spreadability is excellent.

Furthermore, the second acrylic resin may have a hydroxyl value (Ohv) of 95 to 125 mgKOH/g, or 100 to 115 mgKOH/g. When the hydroxyl group of the second acrylic resin is within the above range, clarity and reactivity are improved.

In addition, the second acrylic resin may have a weight average molecular weight (Mw) of 5,500 to 7,500 g/mol, or 6,000 to 7,000 g/mol. When the weight average molecular weight of the second acrylic resin is within the above range, pinhole resistance, chemical resistance, abrasion resistance, and solvent resistance are improved.

In addition, the second acrylic resin may have a solid content of 50 to 80% by weight, 55 to 75% by weight, or 60 to 70% by weight based on the total weight of the resin. When the solid content of the second acrylic resin is within the above range, there is an effect of improving the urethane reactivity.

Furthermore, the second acrylic resin may be included in the composition in an amount of 10 to 30 parts by weight, or 13 to 23 parts by weight based on 5 to 20 parts by weight of the first acrylic resin in the main part. When the second acrylic resin is included within the content range, there is an effect of controlling the drying rate and curing speed of the transparent paint.

3rd acrylic resin

The third acrylic resin lowers the hydroxyl value of the composition to reduce the amount of the curing agent used, thereby improving the economic feasibility of the composition and improving the solid content of the composition.

The third acrylic resin may be directly synthesized in the same manner as described for the first acrylic resin, or a commercially available product may be used.

In this case, the third acrylic resin may have a glass transition temperature of 10°C or less, 1 to 10°C, or 3 to 8°C. When the glass transition temperature of the third acrylic resin is within the above range, there is an effect of improving the paintability and the softness of the coating film.

In addition, the third acrylic resin may have an acid value (Av) of 3 to 15 mgKOH/g, or 5 to 12 mgKOH/g. When the acid value of the third acrylic resin is within the above range, the resin compatibility is improved and the image quality of the coated film is excellent.

Furthermore, the third acrylic resin may have a hydroxyl value (Ohv) of less than 100 mgKOH/g, 50 to 80 mgKOH/g, or 65 to 75 mgKOH/g. When the hydroxyl group of the third acrylic resin is within the above range, there is an effect of improving the sagging property.

In addition, the third acrylic resin may have a weight average molecular weight (Mw) of 2,000 to 3,000 g/mol, or 2,300 to 2,800 g/mol. When the weight average molecular weight of the third acrylic resin is within the above range, there is an effect of lowering the paint viscosity and improving the workability (spray feeling).

In addition, the third acrylic resin may have a solid content of 65 to 90% by weight, 70 to 85% by weight, or 75 to 83% by weight based on the total weight of the resin. When the solid content of the third acrylic resin is within the above range, there is an effect that the content of total volatile organic compounds (TVOC) as a high solid resin is lowered.

Further, the third acrylic resin may be included in the composition in an amount of 25 to 50 parts by weight, or 28 to 45 parts by weight based on 5 to 20 parts by weight of the first acrylic resin in the main part. When the third acrylic resin is included within the content range, there is an advantageous effect in controlling the mixing ratio of the main agent and the curing agent.

4th acrylic resin

The fourth acrylic resin serves to improve the appearance characteristics of the prepared coating film, in particular, image quality.

The fourth acrylic resin may be directly synthesized in the same manner as described for the first acrylic resin, or a commercially available product may be used.

In this case, the fourth acrylic resin may have a glass transition temperature of 10°C or less, 1 to 10°C, or 5 to 10°C. When the glass transition temperature of the fourth acrylic resin is within the above range, the softness of the coating film is increased, thereby improving the slipping properties.

Further, the fourth acrylic resin may have a hydroxyl value (Ohv) of 120 to 160 mgKOH/g, 130 to 155 mgKOH/g, or 135 to 150 mgKOH/g. When the hydroxyl group of the fourth acrylic resin is within the above range, a coating film having excellent pinhole resistance and chemical resistance may be manufactured by improving urethane reactivity.

In addition, the fourth acrylic resin may have a weight average molecular weight (Mw) of 1,500 to 3,500 g/mol, or 2,300 to 3,000 g/mol. When the weight average molecular weight of the fourth acrylic resin is within the above range, chemical resistance and abrasion resistance are excellent, and the surface stickiness of the coating film is minimized and spreadability is improved.

In addition, the fourth acrylic resin may have a solid content of 65 to 90% by weight, 70 to 85% by weight, or 75 to 83% by weight based on the total weight of the resin. When the solid content of the fourth acrylic resin is within the above range, there is an effect of high-solidifying the composition.

Furthermore, the fourth acrylic resin may be included in the composition in an amount of 10 to 30 parts by weight, or 10 to 20 parts by weight based on 5 to 20 parts by weight of the first acrylic resin in the main part. When the fourth acrylic resin is included within the above range, the appearance is excellent and the gloss is increased.

The composition may include the first acrylic resin and the second acrylic resin in a weight ratio of 1: 0.7 to 2.2. When the mixing weight ratio of the acrylic resins is within the above range, gloss and drying properties of the prepared coating film are improved.

The composition may include the first acrylic resin and the third acrylic resin in a weight ratio of 1:1.7 to 3.5. When the mixing weight ratio of the acrylic resins is within the above range, the spreadability of the prepared coating film is improved.

polyester resin

The polyester resin serves to increase the solid content of the composition and improve the appearance, smoothness, scratch resistance and slip properties of the prepared coating film.

The polyester resin may be directly synthesized according to a known method, or a commercially available product may be used. For example, the polyester resin may be prepared by reacting a carboxylic acid with a polyol. In this case, the carboxylic acid is adipic acid (AA), isophthalic acid (IPA), trimmaletic anhydride (TMA), cycloaliphatic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, fumaric acid, maleic anhydride, It may be at least one 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 at least one selected from the group consisting of ,4-hexanediol and 3-methylpentanediol.

In this case, the polyester resin may have an acid value (Av) of 5 to 15 mgKOH/g, or 8 to 13 mgKOH/g. When the acid value of the polyester resin is within the above range, rapid hardening by heat treatment is prevented, thereby preventing a poor appearance of the coating film and a popping phenomenon.

In addition, the polyester resin may have a glass transition temperature (Tg) of -60 to -40 ℃, or -55 to -45 ℃. When the glass transition temperature of the polyester resin is within the above range, the paint spraying feeling (spray feeling) is excellent, and there is an effect of imparting flexibility to the coating film.

Furthermore, the polyester resin may have a hydroxyl value (Ohv) of 150 to 250 mgKOH/g, or 180 to 230 mgKOH/g. When the hydroxyl value of the polyester resin is within the above range, there is an effect of improving the spreadability of the coating film and improving the chemical resistance by the urethane reaction.

In addition, the polyester resin may have a weight average molecular weight (Mw) of 1,500 to 3,500 g/mol, 2,000 to 3,000 g/mol, or 2,400 to 2,900 g/mol. When the weight average molecular weight of the polyester resin is within the above range, there is an effect of forming a smooth and soft (SOFT) coating film of the paint.

In addition, the polyester resin may have a solid content of 80 to 98% by weight, 85 to 95% by weight, or 88 to 93% by weight based on the total weight of the resin. When the solid content of the polyester resin is within the above range, there is an effect of reducing TVOC due to the high solid content.

Furthermore, the polyester resin may be included in the composition in an amount of 1 to 10 parts by weight, or 1 to 5 parts by weight, based on 5 to 20 parts by weight of the first acrylic resin in the main part. When the polyester resin is included within the above content range, there is an effect of improving the appearance, scratch resistance and smoothness of the coating film.

solvent

The transparent coating composition according to the present invention may further include a solvent. In this case, the solvent serves to control the viscosity of the composition, improve dryness, and improve the appearance characteristics and spreadability of the prepared coating film. The solvent is not particularly limited as long as it is commonly used in the transparent coating composition, but may include, for example, at least one selected from the group consisting of aromatics, acetates, alcohols, ketones, and propionates. Specifically, the solvent is an aromatic solvent such as toluene and xylene; 1-Methoxy-2-propyl acetate, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, dimethyl glutarate, dimethyl succinate, dimethyl adipate, propylene glycol methyl ether acetate, butyl carbitol acetate, etc. of acetate-based solvents; alcohol solvents such as n-butanol, propanol and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, methyl butyl ketone and methyl isobutyl ketone; and propionate-based solvents such as ethylethoxypropionate. Moreover, as a commercial item of the said aromatic solvent, Cocosol #100, Cocosol #150, etc. are mentioned.

Furthermore, the solvent may be included in the composition in an amount of 10 to 40 parts by weight, or 20 to 30 parts by weight, based on 5 to 20 parts by weight of the first acrylic resin in the main part. When the solvent is included within the above range, there is an effect of improving workability and drying property by appropriately adjusting the viscosity of the composition.

additive

The transparent coating composition according to the present invention may further include at least one selected from the group consisting of a curing accelerator, an ultraviolet absorber, a surface modifier, a pinhole inhibitor, and a reaction retarder.

The curing accelerator serves to control the curing rate of the composition by accelerating the urethane reaction. In this case, the curing accelerator is not particularly limited as long as it is a commonly used urethane reaction accelerator. For example, the curing accelerator may be a metal compound such as dibutyltin diacetate, dibutyltin dilaurate, stanius octate, dibutyltin mercaptide; tertiary amines such as triethyldiamine, triethanolamine, 1,4-diazocyclooctane, dimethylethanolamine, ethylmorphyrin, dimethylaminoethylmorpholine, and dimethylcyclohexylamine; and alkali metal carboxylates or zinc-based complex compounds.

In addition, the ultraviolet absorber absorbs ultraviolet rays to prevent discoloration of the coating composition, and serves to prevent weather resistance of a coating film prepared from the composition. In this case, the ultraviolet absorber may be used without any particular limitation as long as it is a conventional material that can be used in the coating composition, and for example, a benzotriazole-based agent such as hydroxyphenyl benzotriazole may be mentioned. Further, commercially available products of the ultraviolet absorber include Tinuvin 384 by BASF and eversorb 83 by EVERLIGHT CHEMICAL.

Furthermore, the surface conditioning agent serves to improve the spreadability (leveling property) of the prepared coating film. In addition, the surface modifier may be used without any particular limitation as long as it is a conventional material that can be used in the coating composition, and for example, a silicone-based surface modifier or a fluorine-based surface modifier may be used. In addition, commercially available products of the silicone-based surface conditioning agent include BYK-077, BYK-300, BYK-330, BYK-358, BYK-361, BYK-375, BYK-380, BYK-385, and TEGO ( TEGO's Flow 425, Glide 435, and the like. Further, commercially available products of the fluorine-based surface control agent include DIC (DaiNippon Ink & Chemicals) F-114, F-411, F-450, F-493, F-478, F-479, F-480SF, MCF-350SF, TF-1442 etc. are mentioned.

In addition, the pinhole preventing agent serves to prevent the occurrence of pinholes in the prepared coating film. In this case, the pinhole preventing agent may be used without any particular limitation as long as it is a conventional material that can be used in the coating composition, for example, a polysiloxane-based compound may be mentioned. Moreover, as a commercial item of the said pinhole inhibitor, Byk-051, Byk-052, Byk-054, Byk-057, Byk-063, Byk-065, Byk-072, Byk-085, Byk-088, etc. are mentioned.

In addition, the reaction retardant serves to delay pot life. In this case, the reaction retardant may include, for example, glycol dimercaptopropionate (GDMP, glycol-dimercaptopropionate).

The additive may be included in the composition in an amount of 1 to 20 parts by weight, or 3 to 10 parts by weight based on 5 to 20 parts by weight of the first acrylic resin in the main part. When the additive is included within the content range, the physical properties of the transparent paint may be excellent.

The transparent coating composition according to the present invention includes a main part including the four types of acrylic resins, polyester resins, solvents and additives as described above; and a curing agent unit; That is, the transparent coating composition may be a two-component coating composition including a main part and a curing agent part.

In this case, the solid content may be 50 to 60% by weight, or 54 to 59% by weight based on the total weight of the main part. When the solid content of the main part is within the above range, the TVOC is 430 μg/cm 2 ·hr or less, or 420 μg/cm 2 ·hr or less, thereby having an environmentally friendly effect.

hardener part

The curing agent part may include a curing agent and a curing agent part solvent.

Further, the curing agent may be a polyisocyanate compound. In addition, the type of the curing agent is not particularly limited as long as it can form a urethane bond by reacting with the hydroxyl group of the main part. For example, the curing agent may include an aliphatic polyisocyanate compound without yellowing, specifically, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, tetramethyl xylene diisocyanate, isocyanates or mixtures thereof.

In addition, the curing agent may be included in the composition in an amount of 50 to 80 parts by weight, 55 to 78 parts by weight, or 60 to 75 parts by weight based on 100 parts by weight of the curing agent. When the content of the curing agent is within the above range, it is possible to improve the physical properties of the prepared coating film by forming a stable cured product.

The curing agent solvent serves to adjust the viscosity, dryness and hygroscopicity of the curing agent part. In this case, the curing agent solvent is not particularly limited as long as it can be used in the paint curing agent part, and the solvent disclosed in the solvent may be used.

In addition, the curing agent solvent may be included in the composition in an amount of 20 to 50 parts by weight, 22 to 45 parts by weight, or 25 to 40 parts by weight based on 100 parts by weight of the curing agent part.

The main part and the curing agent part may be mixed in a weight ratio of 1:1 to 5, for another example, 1:2 to 4 to prepare a transparent coating composition.

The transparent paint composition for automobile repair according to the present invention as described above is economical due to high solids content and fast drying speed, and is environmentally friendly due to low VOC content. In addition, the coating film prepared from the transparent coating composition is excellent in paintability, spreadability, pinhole resistance and hardness.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for helping the 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 9. Preparation of the main part

A main part was prepared by mixing the components with the content shown in Table 1.

Ingredients (parts by weight) Example One 2 3 4 5 6 7 8 9 1st acrylic resin-1 95 85 150 - - 150 95 - 150 2nd acrylic resin-1 150 180 130 - - 130 150 - 130 3rd Acrylic Resin-1 300 290 280 - - - - - 280 4th acrylic resin-1 135 160 100 - - - - - 100 No. 1 Acrylic Resin-2 - - - 95 - - - 100 - 2nd acrylic resin-2 - - - 150 - - - 150 - 3rd acrylic resin-2 - - - 300 - 280 - - - 4th acrylic resin-2 - - - 135 - 100 - - - No. 1 Acrylic Resin-3 - - - - 100 - - - - 2nd acrylic resin-3 - - - - 150 - - - - No. 3 Acrylic Resin-3 - - - - 310 - 300 310 - 4th acrylic resin-3 - - - - 120 - 135 120 - polyester resin-1 30 15 50 - - 50 - - - polyester resin-2 - - - 30 - - 30 - - polyester resin-3 - - - - 30 - - 30 50 Solvent-1 125 120.5 125.5 125 140.5 125.5 125 140.5 125.5 Solvent-2 115 100 115 115 100 115 115 100 115 Solvent-3 5 5 5 5 5 5 5 5 5 Solvent-4 10 10 10 10 10 10 10 10 10 hardening accelerator 15 15 15 15 15 15 15 15 15 UV absorber 15 15 15 15 15 15 15 15 15 Surface Conditioning Agent-1 2 2 2 2 2 2 2 2 2 Surface conditioner-2 2 1.5 1.5 2 1.5 1.5 2 1.5 1.5 pinhole inhibitor One One One One One One One One One total 1000 1000 1000 1000 1000 1000 1000 1000 1000

Comparative Examples 1 to 4. Preparation of the main part

A main part was prepared by mixing the components in the content shown in Table 2.

Ingredients (parts by weight) comparative example One 2 3 4 1st acrylic resin-1 - 297.3 105 - 2nd acrylic resin-1 555 105 160 - 3rd Acrylic Resin-1 - - 300 - 4th acrylic resin-1 76- 260 145 - No. 1 Acrylic Resin-4 - - - 95 2nd acrylic resin-4 - - - 150 3rd acrylic resin-4 - - - 300 4th acrylic resin-4 - - - 135 polyester resin-1 - 60 - - polyester resin-4 80 - - 30 Solvent-1 85 102.3 125 125 Solvent-2 65.3 130 115 115 Solvent-3 6 10 5 5 Solvent-4 - - 10 10 Solvent-5 22.3 - - - Solvent-6 20 - - - hardening accelerator 72 8 15 15 UV absorber 15 21 15 15 Surface Conditioning Agent-1 -One 3 2 2 Surface conditioner-2 1.8 2 2 2 pinhole inhibitor 0.6 1.4 One One total 1000 1000 1000 1000

Hereinafter, the manufacturers and product names, or component names, etc. of each component used in Comparative Examples and Examples are shown in Table 3.

ingredient remark 1st acrylic resin-1 NV: 75 wt%, Av: 6 mgKOH/g, Tg: 85°C, OHV: 145 mgKOH/g, Mw: 2,500 g/mol No. 1 Acrylic Resin-2 NV: 72 wt%, Av: 3 mgKOH/g, Tg: 81°C, OHV: 140 mgKOH/g, Mw: 2,000 g/mol No. 1 Acrylic Resin-3 NV: 74% by weight, Av: 10 mgKOH/g, Tg: 90°C, OHV: 150 mgKOH/g Mw: 3,000 g/mol No. 1 Acrylic Resin-4 NV: 65 wt%, Av: 24 mgKOH/g, Tg: 105°C, OHV: 125 mgKOH/g Mw: 4,000 g/mol 2nd acrylic resin-1 NV: 64% by weight, Av: 11 mgKOH/g, Tg: 135°C, Ohv: 107 mgKOH/g, Mw: 6,400 g/mol 2nd acrylic resin-2 NV: 65% by weight, Av: 8 mgKOH/g, Tg: 130° C., Ohv: 100 mgKOH/g, Mw: 6,000 g/mol 2nd acrylic resin-3 NV: 66 wt%, Av: 15 mgKOH/g, Tg: 139°C, Ohv: 115 mgKOH/g, Mw: 7,000 g/mol 2nd acrylic resin-4 NV: 65% by weight, Av: 3 mgKOH/g, Tg: 95°C, Ohv: 90 mgKOH/g, Mw: 5,000 g/mol 3rd Acrylic Resin-1 NV: 75% by weight, Av: 8 mgKOH/g, Tg: 5° C., Ohv: 70 mgKOH/g, Mw: 2,550 g/mol 3rd acrylic resin-2 NV: 80% by weight, Av: 5 mgKOH/g, Tg: 3°C, Ohv: 65 mgKOH/g, Mw: 2,300 g/mol No. 3 Acrylic Resin-3 NV: 83% by weight, Av: 12 mgKOH/g, Tg: 8°C, Ohv: 75 mgKOH/g, Mw: 2,800 g/mol 3rd acrylic resin-4 NV: 60% by weight, Av: 0 mgKOH/g, Tg: -1°C, Ohv: 46 mgKOH/g, Mw: 1,800 g/mol 4th acrylic resin-1 NV: 77% by weight, Tg: 7°C, Ohv: 142 mgKOH/g, Mw: 2,600 g/mol 4th acrylic resin-2 NV: 81% by weight, Tg: 5°C, Ohv: 135 mgKOH/g, Mw: 2,300 g/mol 4th acrylic resin-3 NV: 80% by weight, Tg: 10°C, Ohv: 150 mgKOH/g, Mw: 3,000 g/mol 4th acrylic resin-4 NV: 60% by weight, Tg: -7°C, Ohv: 165 mgKOH/g, Mw: 3,700 g/mol polyester resin-1 NV: 90 wt%, Ohv: 200 mgKOH/g, Tg: -50°C Av: 10 mgKOH/g, MW: 2,600 g/mol polyester resin-2 NV: 92 wt%, Ohv: 180 mgKOH/g, Tg: -55°C Av: 8 mgKOH/g MW: 2,400 g/mol polyester resin-3 NV: 88 wt%, Ohv: 230 mgKOH/g, Tg: -45°C Av: 13 mgKOH/g MW: 2,900 g/mol polyester resin-4 NV: 60 wt%, Ohv: 138 mgKOH/g, Tg: -66°C, Av: 1 mgKOH/g MW: 1,000 g/mol Solvent-1 Butyl acetate Solvent-2 Propylene glycol methyl ether acetate Solvent-3 Butyl Carbitol Acetate Solvent-4 acetone Solvent-5 xylene Solvent-6 Methyl ethyl ketone (MEK) hardening accelerator 5% dibutyltinbis[(1-oxododecyl)oxy]stannane solution (solvent: xylene) UV absorber Manufacturer: EVERLIGHT CHEMICAL, product name: eversorb 83 Surface Conditioning Agent-1 Manufacturer: BYK-Chemical, Product name: BYK-358 Surface conditioner-2 Manufacturer: TEGO, Product name: Flow 425 pinhole inhibitor Manufacturer: BYK-Chemical, Product name: BYK-072

Reference example. Preparation of curing agent part

46 parts by weight of polyisocyanate compound-1 (ingredient name: hexamethylene diisocyanate, NCO content: 20.9% by weight, viscosity: 375 mPa·s, solid content: 90% by weight), 22 parts by weight of polyisocyanate compound-2 (component name: hexamethylene di Isocyanate, NCO content: 21.8% by weight, viscosity: 3,000 mPa·s, solids: 100% by weight, Mw: 2,149 g/mol), 1.5 parts by weight of triethyl ortho-formate (boiling point: 146° C., Mw: 148.23 g) /mol), and 30.5 parts by weight of butyl acetate (specific gravity: 0.881, flash point: 24°C, melting point: 78°C) to prepare a curing agent part.

Experimental Example 1. Characterization of the coating film

A transparent coating composition was prepared by mixing the main part prepared in Examples 1 to 9 and Comparative Examples 1 to 4 and the curing agent part of Reference Example in a weight ratio of 3:1. After that, a coating film having a dry thickness of 50 to 60 μm was formed by coating the transparent coating composition on the specimen twice by a wet-on-wet coating method, and then the physical properties of the coating film were measured in the following way. , the results are shown in Table 4 below.

(1) Total volatile organic compounds (TVOC) emissions

For example, a specimen with a 10 cm × 10 cm (width × length) coating film is placed in a chamber at 25° C. and 50% relative humidity (RH), and a thermal desorption device (ATD-400, Markers, UK) and an adsorption tube (Tenax TA) are applied. After measuring the emission of volatile organic compounds using the In this case, the formula for calculating the content of Article 3 of the National Institute of Environmental Sciences Notice No. 2005-11 was applied.

(2) Spray feeling

SATA HVLP gun 1.4mm nozzle size, discharge volume 2 times, air pressure of 1.7 bar, spaced 25cm apart from the specimen 45cm X 45cm (width X length) and applied 5 times from top to bottom left and right reciprocating 5 times The spray feeling was evaluated based on the amount of paint arriving at the

(3) Paintability

After coating the paint, it was dried at 60° C. for 30 minutes, and then the coating film thickness was measured to give paintability.

(4) Spreadability

After drying in the same manner as in item (3), the spreadability of the coating film was measured based on the OP value and the DOI value using a WAVESCAN DOI as a measuring instrument.

(5) sagging

The thickness of the coating film was measured at the point where the paint started to flow when it was left in a vertical position after painting.

(6) curing conditions

After coating the coating material, the time for hardening of the coating film when dried at 60° C. was measured. At this time, the hardening time was measured by measuring the time the coating film did not leave marks when it was twisted left and right by pressing the coating film strongly by hand.

(7) pinhole resistance

After applying the paint, it was dried at 60° C. for 30 minutes, and the presence and extent of pinholes in the paint film were checked.

As shown in Table 4, it was found that the coating films prepared from the compositions of Examples 1 to 9 had better physical properties than the coating films prepared from the compositions of Comparative Examples 1 to 4.

Experimental Example 2.

A transparent coating composition was prepared by mixing the main part prepared in Examples and Comparative Examples and the curing agent part of Reference Example in a weight ratio of 3:1. Then, a base paint (manufacturer: KCC, product name: UT5901) is coated on the electrodeposition specimen (30 cm × 30 cm, width × length) to a dry thickness of 20 μm, and the transparent coating composition is applied to a dry thickness of 60 μm on the base coating film. After coating, drying and curing, a transparent coating film was formed to obtain a final coating film. Thereafter, the physical properties of the final coating film were measured in the following manner, and the results are shown in Table 5 below.

(1) hardness

The hardness of the final coating film was measured by measuring the number of reciprocations of the pendulum using a pendulum hardness tester.

(2) Appearance of the coating film

The gloss (LU), image sharpness (SH), and smoothness (OP) of the final coating were measured using Wave Scan DOI (BYK Gardner), an automobile exterior measuring instrument, and the overall appearance evaluation value (CF) was calculated using the measured physical properties. It was calculated by Equation 1 below. At this time, it was determined that the higher the CF, the better the appearance characteristics of the coating film.

[Equation 1]

CF = LU×0.15 + SH×0.35 + OP×0.5

(3) SW (Short Wave) and LW (Long Wave)

Short wave and long wave values of the final coating film were measured using Wave Scan DOI (BYK Gardner), which is an automobile exterior measuring instrument.

(4) Seon Young-seong (DOI, Distinctness of Image )

The image quality (DOI) of the final coating film was measured using Wave Scan DOI (BYK Gardner), which is an automobile exterior measuring instrument.

As shown in Table 5, the coating films prepared from the compositions of Examples 1 to 9 had superior hardness than the coating films prepared from the compositions of Comparative Examples 2 to 4, and compared to the coating films prepared from the composition of Comparative Example 1, CF, LU, It was found that smoothness such as SH and DOI was excellent.

Claims (7)

Including a first acrylic resin having a glass transition temperature of 70 °C or higher and less than 100 °C, a second acrylic resin having a glass transition temperature of 100 °C or higher and 160 °C or lower, and third and fourth acrylic resins and polyester resins having a glass transition temperature of 10 °C or lower and,
The hydroxyl value of the third acrylic resin is lower than the hydroxyl value of the fourth acrylic resin,
The third acrylic resin has an acid value of 3 to 15 mgKOH/g, a hydroxyl value of less than 100 mgKOH/g, and a weight average molecular weight of 2,000 to 3,000 g/mol, a transparent paint composition for automobile repair. The method according to claim 1,
The first acrylic resin has an acid value of 3 to 15 mgKOH/g, a hydroxyl value of 130 to 160 mgKOH/g, and a weight average molecular weight of 1,500 to 3,500 g/mol, a transparent paint composition for automobile repair. The method according to claim 1,
The second acrylic resin has an acid value of 5 to 30 mgKOH/g, a hydroxyl value of 95 to 125 mgKOH/g, and a weight average molecular weight of 5,500 to 7,500 g/mol, a transparent paint composition for automobile repair. delete The method according to claim 1,
The fourth acrylic resin has a hydroxyl value of 120 to 160 mgKOH/g and a weight average molecular weight of 1,500 to 3,500 g/mol, a transparent paint composition for automobile repair. The method according to claim 1,
The polyester resin has an acid value of 5 to 15 mgKOH/g, a glass transition temperature of -60 to -40°C, and a hydroxyl value of 150 to 250 mgKOH/g, a transparent paint composition for automobile repair. The method according to claim 1,
The transparent coating composition comprises 5 to 20 parts by weight of the first acrylic resin, 10 to 30 parts by weight of the second acrylic resin, 25 to 50 parts by weight of the third acrylic resin, 10 to 30 parts by weight of the fourth acrylic resin, and 1 to A transparent paint composition for automobile repair, comprising 10 parts by weight of a polyester resin.