KR20110062223A - Surface-treated steel sheet coated with low voc high-solid coatings - Google Patents

Abstract

PURPOSE: A surface-treated steel sheet coated with low VOC high-solid paint is provided to improve processability by adding hydroxypivalyl hydroxypivalate. CONSTITUTION: A surface-treated steel sheet coated with low VOC high-solid paint comprises high-solid polyester resin, hardening resin, curing catalyst, solvent, and additive. The high-solid polyester resin comprises polyhydric alcohol, polyhydric acid, capping materials, and solvent. The polyhydric alcohol comprises hydroxypivalyl hydroxypivalate.

Description

Surface-Treated Steel Sheet Coated with Low VOC High-Solid Coatings

The present invention relates to a steel sheet for PCM, and more particularly, high solids having excellent workability while reducing the amount of solvent used by high solidification of paints, thereby reducing volatile organic chemicals (VOC). It relates to a surface-treated steel sheet for PCM coated with a coating composition.

The conventional polyester polymer resin for PCM (Pre Coated Metal) steel plate (hereinafter also referred to as 'high polymer') paint uses a polymer polyester resin as a basic resin and a melamine resin compound as a curable resin, and promotes curing therein. A coating composition prepared by containing a curing catalyst, and a small amount of additives such as an antifoaming agent and a leveling agent was used. This high polymer coating composition requires a large amount of organic solvent to lower the viscosity of the paint in order to maintain a smooth coating workability due to the high viscosity of the resin, and because of this, the solvent is volatilized to the atmosphere as the coating film is formed after coating Emission of volatile organic compounds is a major cause of air pollution.

Each paint manufacturer has continued to develop eco-friendly paints such as EB paints with EB hardening system, which accepts and powders PCM paints and responds to the global eco-friendly flow. However, it is difficult to commercialize in PCM coatings due to the inexpensiveness or the limitation of coating properties due to expensive material costs.

In a first aspect of the invention,

i) High solid containing polyhydric alcohol, polyacid, capping agent and solvent, weight average molecular weight 11,000-15,000, hydroxyl value 15-25 mgKOH / g, glass transition temperature 30-50 ℃, solid content ratio 55-65% Polyester resins;

ii) cured resins;

iii) curing catalyst;

iv) solvents; And

v) Provides a PCM coated steel sheet coated with a high solid coating composition comprising other additives.

Here, the capping agent is used selected from the group consisting of nonanoic acid, benzoic acid, p-tertiarybutyl benzoic acid.

In a second aspect of the invention,

Chemically coated metal plate or plated layer;

i) High solid containing polyhydric alcohol, polyacid, capping agent and solvent, weight average molecular weight 11,000-15,000, hydroxyl value 15-25 mgKOH / g, glass transition temperature 30-50 ℃, solid content ratio 55-65% Polyester resin,

ii) cured resin,

iii) curing catalyst,

iv) a solvent, and

v) a primer coating film coated with a high solid coating composition comprising other additives; And

The top coat film; is laminated sequentially to provide a PCM surface treatment steel sheet.

In order to reduce the volatile organic compounds of the general polyester high polymer coating composition for PCM, the present inventors have continued the research on high solids to increase the solid content in the paint, and the flexible resin of the super high solid polyester resin Paint composition technology for PCM (pre-coated metal) for construction materials that reduces the emission of volatile organic components by increasing the solid content by complementing the physical properties with high-hardness resin of high-solid polyester as the main resin Developed. Details are described in Korean Patent No. 692931 ("Paint composition for environmentally friendly PCM"), the entirety of which is incorporated herein by reference.

However, in the case of heading 692931, the weight average molecular weight of the polyester resin is about 7000 to 9000, and when applied for general building materials, it shows a VOC reduction effect due to high solidification, but it does not affect the molecular weight of general PCM paint for home appliances. Due to its low molecular weight, it is insufficient to be used as a home appliance that requires deep workability in the manufacturing process. Thus, the research has been carried out to develop paints having workability, hardness, and various physical properties suitable for use in PCM coatings for home appliances, automobiles, and the like, and PCM steel plates having surface treatments thereof.

In general, the coated steel sheet for home appliances should be free of cracks in the 1t bending film during the 180 degree bending test. In other words, unlike the building materials such as walls, since the deep workability is required in the manufacturing process in order to apply to home appliances such as TV back panels, processability is considered to be a very important factor in the expression of the effect of the home appliance paint.

However, in the case of resins used as PCM paints for general home appliances, the weight average molecular weight is 25,000 to 28,000 and the solid content is about 50%, and it is common to use a low solid linear polyester resin. In this case, the workability is good, but there is a problem in that high solidification is difficult.

Therefore, the present inventors have implemented VOC-reduced high-solidification in PCM paints for home appliances, and at the same time, solved a problem of weak processability due to lower molecular weight due to high-solidification, and studied to ensure good physical properties of the coating film.

As a result, high-solidification is achieved by managing the raw material monomers, additives, and polymerization reactions constituting the resin, while in the case of household appliances, the higher the molecular weight is, the better the coating film flexibility is. The molecular weight was controlled high.

In particular, by using a capping agent in the resin manufacturing process to control the molecular weight of the resin to a desired level, by maintaining a narrow molecular weight distribution excellent physical properties (processability) at low viscosity, low molecular weight and high solidification I found out.

That is, in general household polyester resins maintain a high molecular weight (25,000 ~ 35,000) of the high level in order to ensure processability and durability. However, by using a capping agent which terminates the reaction by blocking one end of the resin main chain as in the present invention, when the molecular weight reaches the level of about 11,000, the polymerization reaction is forcibly terminated, whereby the resin molecular weight is preferably 11,000. It was controlled to have a narrow distribution range as ˜15,000, more preferably 13,000 to 15,000.

As an important characteristic, the lower the molecular weight, the greater the hydroxy value, most of which results in a change over time resulting in a weakening of the bending (bending). By using the capping agent, which is a characteristic of the present invention, the hydroxy value was able to reduce the molecular weight in half while maintaining the same value as the existing polymer resin.

In addition, it is also necessary to maintain an appropriate level of viscosity for the use of a roll coater in the process of forming the coating film, so that the viscosity is high so that the solid content is high and the viscosity is low, so that the amount of solvent for dilution can be reduced. It also needed to be controlled.

Therefore, among the solvents used to dissolve the solid content as an example, the amount of the true solvent increased.

In addition, by adding hydroxy pivalyl hydroxy pivalate (HPHP) having excellent processability in the raw material monomer of the high-solid polyester resin, the workability that is weak at a relatively low molecular weight is further supplemented.

In addition, in terms of cured resin, melamine cured resin was conventionally used only, but in the present invention, a urethane resin was introduced to further compensate for the decrease in processability.

When the coating composition according to the present invention is used, the ratio of solid content, which is a non-volatile content, is higher than that of the general coating composition for home appliances, while the viscosity is kept the same, resulting in a significant reduction in the amount of solvents that are volatile organic compounds. The unit requirement of the paint was greatly reduced and the properties such as workability and hardness could be complemented.

Therefore, it can contribute to cost reduction and reduction of environmental pollutant generation.

The method of manufacturing a PCM surface-treated steel sheet according to the present invention by coating a high-solid coating material mixed with the above components, by non-chromate pre-treated steel sheet in a conventional manner, to improve adhesion and corrosion resistance thereon The high solid composition paint is coated with a dry coating thickness of 3-10 microns, heated to form a primer coating film, and then coated with a top coat to have a dry coating thickness of 10 to 25 microns, followed by heating. It consists of If necessary, additional CLEAR paint may be applied. There is no restriction | limiting in particular about the said primer, top coat, and CLEAR coating method, The spray method, roll coating method, air spray method, airless spray method, etc. which are generally used can be used.

Hereinafter will be described in detail with respect to the steel sheet and primer coating film constituting the PCM surface treatment steel sheet according to the present invention.

Steel plate

The steel sheet used as the surface-treated steel sheet of the present invention is not particularly limited, and the sheet metal itself, such as cold-rolled steel sheet, hot-rolled steel sheet, or hot-dip galvanized steel sheet, electro-galvanized steel sheet, hot-dip galvanized steel sheet, aluminum plated steel sheet, As long as generally known plating layers, such as an aluminum- zinc alloy plated steel plate and a steel plate, such as a stainless steel plate, an aluminum plate, a copper plate, a titanium plate, a magnesium plate, and other plated metal plates, are formed, most are applicable. In addition, it is more preferable to perform a known chemical conversion treatment such as phosphate coating, chromate, non-chromate, etc. in order to provide interlayer adhesion between the base steel sheet and the primer coating film and basic corrosion resistance.

Primer coatings

The primer coating film is an important factor that affects the interlayer adhesion between the surface of the steel sheet and the top coat, coating hardness, chemical resistance, corrosion resistance, and the like. A high-solid paint, which will be described in detail below, may be used as a primer for home appliances. It can be applied even when high processability is required. In order to impart corrosion resistance to the primer paint of the present invention, a toxic or non-toxic anti-rust pigment may be used in addition to the existing TiO 2 white pigment.

3-10 micrometers is preferable and, as for the dry coating film thickness of a primer coating material, 4-6 micrometers is more preferable. The reason for this is that when the thickness of the dry coating film is less than 3 µm, the rust preventive property and adhesion are inferior, and when the thickness of the dried coating film is greater than 10 µm, surface appearance defects and economical efficiency are inferior.

At this time, the coating method is not limited to the roll coating, it also includes a curtain floor method used for PCM steel sheet.

As the baking conditions, the atmosphere temperature conditions to be baked should be changed depending on the width, thickness and line speed of the base metal plate, but it is preferable to make the PMT (peak metal temperatur) 190-220 ° C in the continuous line of the PCM.

Hereinafter, the polyester main resin, the cured resin, the curing catalyst, the solvent, and other additives constituting the high solid coating composition coated on the PCM surface-treated steel sheet according to the present invention will be described in detail.

High Solid Polyester Resin

The high-solid polyester main resin according to the present invention is a polymerization product of a polyhydric alcohol (for example, propylene glycol, ethylene glycol, etc.) and a polyacid monomer, and as the polyhydric alcohol component of the high-solid polyester resin, ethylene glycol, Propylene glycol, 1,4-butylene glycol, trimethylolpropane, HPHP (hydroxypivalyl hydroxypivalate), 1,6-hexanediol, neopentyl glycol, methylpropanediol, cyclohexanedimethanol, Hydrogenate bisphenol A, ethylene oxide addition bisphenol A, propylene oxide addition bisphenol A, ethylene oxide addition bisphenol F, propylene oxide addition bisphenol F, ethylene oxide addition bisphenol S, propylene oxide addition bisphenol S, etc. are mentioned. These may be used by mixing one or more than two.

Preferably, the polyhydric alcohols used for the high solid polyester resin may include a polyhydric alcohol including HPHP (Hydroxy pivalyl hydroxy pivalate) in order to improve processability of the high solid resin. 20 to 40% of the amount.

The HPHP is a high functional ester-glycol used to make polyester resins, which is structurally similar to neopentylglycol, and is substantially the same in terms of structure / characteristics. When HPHP is added to the resin, it maintains drying and mechanical properties as in the case of neopentylglycol, and gives flexibility to the coating, and is superior to neopentylglycol in terms of effects. Therefore, it can exhibit the outstanding effect in the use of the chip | tip for home appliances which has chip resistance, and the coating use which requires a high level of flexibility, appearance durability, and flowability.

In the embodiment of the present invention, HPHP is preferably used in the 4.5 ~ 6.5% of the total polyester main resin weight, less than 4.5% is difficult to obtain the desired workability improvement effect, when exceeding 6.5% may cause problems of hardness degradation Because.

Examples of the polyhydric acid used in the preparation of the high-solid polyester resin include phthalic anhydride, tetrahydro phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, azelaic acid, sebacic acid, cyclohexadiacid and trimellis. Tic anhydride, and the like. These can be used individually or in mixture of 2 or more types.

Preferably, the polyhydric acid is an aromatic acid including at least one selected from the group consisting of phthalic anhydride, tetrahydro phthalic anhydride, adipic acid, isophthalic acid and terephthalic acid. Contains 40%.

In the present invention, in addition to the polyhydric alcohols and polyvalent acids, which are the basic monomers constituting the main resin, a capping agent was used to control the molecular weight and the molecular weight distribution range of the resin to achieve high solidification. As a capping agent used in the preparation of the high solid polyester resin according to the present invention, at least one selected from the group consisting of Nonanoic acid, Benzoic acid, and P-tertiarybutylbenzoic acid may be used. To achieve the control effect and workability complementary effect.

In the present invention, the capping agent is preferably used at 1.0 to 2.5% of the total polyester main resin weight, but less than 1.0% may be inadequate to reach high solidification, and the cause of deterioration in workability due to high viscosity This is because when it exceeds 2.5%, various physical properties such as workability may decrease.

The diluent used in the polymerization of the high-solid polyester resin according to the present invention is not limited to the above, but it is possible to optimize the solubility of the resin and to provide stability to the popping of the coating film and to adjust the resin content. Xylene (XY, co-solvent) / methoxy propanol (PM, anti-solvent) is recommended, the ratio can be arbitrarily adjusted, but the viscosity change according to the seasonal temperature difference, the solid content of the high-solid resin can be adjusted 7: 3 It is preferable that it is about degree. The amount of solvent used can be suitably used within the range in which the solid content can be dissolved, that is, within the range of 35 to 50% of the total resin weight.

Furthermore, in order to activate acid alcohol reaction during addition polymerization, a tin-based metal catalyst such as DBTO may be used, and the content thereof is preferably limited to about 0.05% by weight in consideration of the high cost and toxicity.

The high-solid polyester main resin according to the present invention preferably has a weight average molecular weight within the range of 11000 to 15000 in consideration of solvent saving effect due to high solidification, workability and processability according to viscosity, and a hydroxyl value of 15. To 25 mgKOH / g, the glass transition temperature (Tg) is preferably within 30 ~ 50 ℃.

Hardening resin

In the present invention, the cured resin for the main resin is used by mixing the melamine resin and urethane cured resin 1: 1 to 1: 0.7, 2 to 8% by weight based on the total weight of the total composition, among which the urethane cured 1-5% by weight of resin is added to prepare a high solid paint.

In the present invention, when the urethane resin is excessively used as the curing resin, yellowing may occur in the high temperature baking type curing method, so it is preferable to use the melamine resin in combination with the melamine resin. It is advantageous in hardness, but when using an acid catalyst, the reaction rate is slightly slower at high temperature than the methoxy melamine resin, and the processability is lowered. It is preferable to use a melamine resin containing a methoxy group having excellent properties.

When the urethane cured resin is mixed with the selected methoxy type melamine resin in a ratio of 1: 1 to 1: 0.7, the basic physical properties such as processability of the coating film are made to be equal to or higher than those of the existing paint. poor processability of a coating film, and 1: 1 if it exceeds the processability of the coating film is not preferable because it is a disadvantage that the surface hardness of a good coating film decreases.

Urethane cured resin is used by mixing 1 to 5% by weight, and the total content of the cured resin is preferably used in the range of 2 to 8% by weight based on the total weight of the entire composition. If the total content of the cured resin is less than 2% by weight, the chemical resistance, solvent resistance, hardness, etc. of the coating film is lowered, whereas if the content is more than 8% by weight it is not preferable because the workability is reduced.

Curing catalyst

The curing catalyst used to promote the curing reaction between the polyester main resin and the curing resin is p-toluene sulfonic acid (p-TSA) or dinonylnaphthalene sulfonic acid (DNNSA), dinaphthalene disulfonic acid (DNNDSA), fluoro sulfonic acid The sulfonic acid selected from among those neutralized with amine or epoxy may be used. Tin catalyst (DBTDL; dibutyl tin dilaurate) is also used for urethane crosslinking.

The curing catalyst is contained in the range of 0.1 to 0.2% by weight based on the total coating composition, when the content is less than 0.1% by weight, the effect of promoting the curing is insufficient, and when the content exceeds 0.2% by weight, the coating film hardens so rapidly that Popping occurs in the coating during coating operation or causes workability deterioration.

solvent

The coating composition of the present invention contains an appropriate amount of an organic solvent in consideration of handling, coating work characteristics, etc., wherein the organic solvent that can be used is an anti-solvent which directly dissolves the polyester polymer resin, and is based on ester, ether and alcohol. It is preferable to mix and use a petroleum solvent as a co-solvent which dilutes a dissolved molecule | numerator, a ketone solvent, etc., and a dissolved molecule.

Here, examples of the ester solvents include ethyl acetate, n-butyl acetate, cellosolve acetate, propylene glycol monomethyl acetate, 3-methoxy butyl acetate, and the like. Examples of the ether solvent include methyl cellosolve, ethyl cellosolve, ethylene glycol butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, etc. of Union Carbide. Alcohol solvents include ethanol, isopropanol, n-butanol, methyl alcohol, amyl alcohol, cyclohexanol and the like. Cyclohexanone, methylamyl ketone, diisobutyl ketone, methyl ethyl ketone, etc. are mentioned as a ketone solvent. Examples of the petroleum-based solvents include Cocosol # 100 and Cocosol # 150 of Daiko Corp.

In particular, by using the petroleum solvent and the petroleum co-solvent mixture consisting of the ketone solvent and ester solvent in a specific ratio, while achieving a high solid content and at the same time it can bring a low viscosity and VOC reduction effect despite the solid content ratio. . In one example of the present invention by using a mixture of the ketone solvent 8 ~ 12% and the ester solvent 3 ~ 7% based on the total weight of the coating composition, using the true solvent content of 11 to 20%, and the petroleum crude solvent content 10-15% was used. In other words, by increasing the amount of solvent used to maintain the low viscosity effect.

If the ketone solvent is used at less than 8%, the downward effect of the paint viscosity is reduced, and if it is used more than 12%, there is a problem that workability is lowered, such as poor paintability of the paint. If the ester solvent is used less than 3%, the downward effect of the paint viscosity is reduced, when used more than 7% there is a problem that the workability is lowered.

Other additives (leveling agents, defoamers and pigments)

Because of the high probability of air bubbles during the high-speed stirring to prepare the coating composition, a coloring pigment generally added in the preparation of the coating composition is required so as to exhibit the hiding power of the acrylic, vinyl or silicone leveling agent, the antifoaming agent and the coating film to the above components. Can be added accordingly. In one example, the leveling agent and the antifoaming agent are preferably used at 0.1 to 0.2% by weight, respectively, based on the total weight of the entire coating composition. If the content of the leveling agent and the antifoaming agent is less than 0.1% by weight, the appearance of the dry coating is poor. If the content of the leveling agent is more than 0.2% by weight, the adhesion of the coating film due to the residual chemicals is not preferable.

Examples of such leveling agents and antifoaming agents include Disparon L-1980, Disparon L-1984, Disparon AP-30, BYK356 by Kusumoto Chemical Co., Ltd., and the like.

In addition, the coating composition of the present invention may be used as a transparent coating composition containing no pigment, but is generally used as a coating composition containing a coloring pigment. As the coloring pigments, both organic / inorganic materials available in the field of coating compositions can be used. When applied to the undercoat, non-toxic anti-rust pigments containing lead or chromium, including strontium chromate, may optionally be used for basic rust protection.

In addition, the coating composition of the present invention may include a sieving pigment such as talc, clay, silica, mica, alumina, fillers, pearls, metallic, and the like. The pigment may be contained in the range of 10 to 40% by weight based on the total weight of the entire coating composition.

Example

The high-solid paint and the general LOW SOLID paint blended on the chemically treated galvanized steel sheet in the amounts shown in Table 3 below, and then dried for 30 seconds at a steel plate temperature of 210 degrees with a dry film thickness of 5 microns, and then applied to the same home appliance. Each steel sheet was produced by coating a top coat.

Table 1 below shows the synthesis results of the conventional LOW SOLID resin and the resulting resin characteristic values as a preparation example and reference for the high-solid resin according to an embodiment of the present invention.

Original LOW Solid Resin High Solid Resin Monomer Neopentyl glycol 21 20 Trimethylolpropane 0.5 0.6 HPHP - 5.5 Monomer Adipic acid 11 12 Isophthalic acid 7.8 11 Terephthalic acid 3.5 2.8 Phthalic anhydride 6.2 7.2 Capping agent Nonanoic acid - 1.5 solvent XL / PM ¹⁾ = 7/3 50 39.4 Property value importance 1.05 1.05 Viscosity ²⁾ Z- Z- Solid content 51 62 Molecular weight ³⁾ 26000 14000 Hydroxyl value 17 22

1) XL / PM: xylene / methoxy propanol,

2) Viscosity: 60% solution (25 degrees Gardner),

3) Molecular weight: weight average molecular weight (GPC).

In Table 2, the physical properties of the preparation of the high-solid resin and the conventional resin according to an embodiment of the present invention shown in Table 1 were compared, and if the physical properties were bad, X was good, △, and excellent O was represented.

Original LOW Solid Resin High Solid Resin Machinability O O Hardness O O Workability O O

As shown in Tables 1 to 2, as a result of comparing and examining the properties and physical properties of the resin, the high solids polyester resin has a higher solid content value, the hydroxyl value is slightly higher than the conventional LOW SOLID resin, the molecular weight is significantly lowered On the other hand, it can be seen that the viscosity does not have a large difference.

Table 3 shows the components of the paint prepared using the high-solid resin and the conventional LOW SOLID resin according to an embodiment of the present invention and the physical properties of the resulting paint.

Conventional LOW Solid Paint High Solid Paint High polymer resin 39 - High solid resin - 39 Curing Resin (Melamine) 3.6 2.3 Curing Resin (Urethane) - 2 Pigment (TiO ₂ ) 24 29 Hardening accelerator 0.1 0.1 DBTDL ¹⁾ - 0.1 Leveling agent 0.2 0.2 Antifoam 0.1 0.1 CH ²⁾ 5 10 CA ³⁾ - 5 Petroleum system (K150, K100) 27 12.3 Machinability O O Hardness O O

1) DBTDL: Dibutyl tin dilaurate

2) C.H: cyclohexanone

3) C.A: cellosolve acetate

The physical properties of the coating film obtained by coating the high-solid paint and the existing paint according to an embodiment of the present invention were measured and the results are shown in Table 4 below.

Conventional LOW Solid Paint High Solid Paint Machinability O O Hardness O O Curing degree O O Acid resistance O O Alkali resistance O O Boiling water resistance O O Adhesion O O Corrosion resistance O O

In addition, when the high solids and the conventional paints according to an embodiment of the present invention based on the requirements per ton and dry coating 5㎛ based on 0.5 ton standards, the effect of reducing the paint and solvent requirements is calculated and the results are shown in Table 5 below. It was.

Original paint High Solid Paint Viscosity 80 80 importance 1.13 1.10 Solid content 48 58 Solvent weight 0.93 0.93 SVR ¹⁾ 36.82 50.23 Unit requirement (g / m ² ) 15.35 10.90 Paint savings 29% VOC Reduction Rate 41%

1) SVR: Solid by Volume Ratio

In view of the reduction effect, it was confirmed that the high-solid paint is an environmentally friendly paint that improves the cost competitiveness by reducing the paint requirement and improves the cost competitiveness and greatly improves the environment by reducing the volatilization of the solvent. In particular, the solvent requirement of the paint is 15.35 g / m ² and the high-solid paint is 10.90 g / m ² .The solvent requirement is improved by 29% in the same amount of paint, but when the high-solid paint is applied, the paint itself is used. Since the amount is reduced, the total amount of solvent volatilization effect is reduced by 41%, which is a significant contribution to environmental improvement.

0.45T of GI steel sheet was degreased with methyl ethyl ketone, and the paint prepared by using the high-solid resin and the existing resin of Synthesis Example 1 of Table 1 and Table 2 based on the paint composition of Table 3 was dried. Bar coating was carried out so as to be μm, followed by baking, and the coating film for home appliances was baked at 20 μm at an ambient temperature of 280 ° C. (PMT 232 ° C.) at a dry coating thickness of 20 μm to prepare a coating film specimen.

On the other hand, the coating properties test method for the coating film specimens are as follows.

1. Machinability: Cracks were observed when the specimens were observed with a magnifying glass at 30x magnification after 1T-bending test.

2. Curing degree: MEK x 2 kg x linearly reciprocated to measure the number of times the coating film damage occurred.

3. Hardness: The hardness of the coating film was tested with a Mitsubishi (Mit-Bit Uni) pencil.

4. Acid resistance: 5% aqueous acetic acid (HAc) solution was dropped on the coating surface, and the cover was capped so as not to evaporate. After 48 hours at 25 ° C., the state of the coating surface was observed. (Double-circle) is excellent, (circle) is good, (triangle | delta) is normal and X means bad.

5. Alkali resistance: 5% sodium hydroxide (NaOH) aqueous solution was dropped on the coating surface, and the lid was covered with a solution to prevent evaporation. After 48 hours at 25 ° C., the condition of the coating surface was evaluated.

6. Boiling Water Resistance: Measured at 100 ° C. under 1 hour conditions.

7. Adhesiveness: The coating film was cut into 100 squares at 1mm intervals, and peeled off when it was completely attached and removed using OPP Tape.

8. Corrosion resistance: Corrosion was measured under 5% NaCl x 35 ° C x 500 hours.

Claims (9)

i) High solid containing polyhydric alcohol, polyacid, capping agent and solvent, weight average molecular weight 11,000-15,000, hydroxyl value 15-25 mgKOH / g, glass transition temperature 30-50 ℃, solid content ratio 55-65% Polyester resins; ii) cured resins; iii) curing catalyst; iv) solvents; And v) PMM surface treated steel sheet coated with a high solid coating composition comprising other additives. The method of claim 1, Said polyhydric alcohol comprises hydroxy pivalyl hydroxy pivalate, PCM surface treatment steel sheet. The method of claim 1, The capping agent is selected from the group consisting of nonanoic acid, benzoic acid, p-tertiarybutyl benzoic acid, PCM surface treatment steel sheet. The method of claim 1, Polyhydric alcohol 20-40%; Polyacid 20-40%; Capping agent 1-2%; And 35% to 55% solvent. The method of claim 1, The cured resin is used by mixing the melamine resin and urethane cured resin, 2 to 8% by weight based on the total weight of the total composition, among which 1-5% by weight of the urethane cured resin, PCM surface treatment Grater. The method of claim 1, The solvent is based on the total weight of the total composition, containing a solvent composed of ketone-based solvents 8 to 12% and ester solvents 3 to 7%, and petroleum coarse solvent 10-15%, PMM surface treatment steel sheet. The method of claim 1, 30 to 45% high-solid polyester resin, 2 to 8% by weight of curing resin, 0.1 to 0.2% by weight of curing catalyst, 21 to 35% by weight of solvent, 0.1 to 0.2% by weight of leveling agent, antifoaming agent A PCM surface-treated steel sheet coated with a high solid coating composition comprising 0.1 to 0.2% by weight and pigments 10 to 40% by weight. Chemically coated metal plate or plated layer; i) High solid containing polyhydric alcohol, polyacid, capping agent and solvent, weight average molecular weight 11,000-15,000, hydroxyl value 15-25 mgKOH / g, glass transition temperature 30-50 ℃, solid content ratio 55-65% Polyester resin, ii) cured resin, iii) curing catalyst, iv) a solvent, and v) a primer coating film coated with a high solid coating composition comprising other additives; And A top coat film; is sequentially stacked, PCM surface treatment steel sheet. The method of claim 8, The top coat film, i) High solid containing polyhydric alcohol, polyacid, capping agent and solvent, weight average molecular weight 11,000-15,000, hydroxyl value 15-25 mgKOH / g, glass transition temperature 30-50 ℃, solid content ratio 55-65% Polyester resin, ii) cured resin, iii) curing catalyst, iv) a solvent, and v) A PCM surface treated steel sheet, which is a top coat, coated with a high solid coating composition, comprising other additives.