KR20070072136A - High weatherability regin compositions for electrodeposition coating - Google Patents

Abstract

Provided are high weatherability resin composition for an electrodeposition paint which is high in weather resistance, a method for preparing a polyepoxide-polyoxyalkylene diamine resin, and an electrodeposition paint composition containing the resin composition. The high weatherability resin composition comprises 25-35 parts by weight of a main resin comprising an aliphatic polyol and a polyepoxide; 12-16 parts by weight of a curing agent comprising a trivalent or more valent alcohol and an aliphatic or alicyclic isocyanate blocked with a primary or secondary alcohol; and 1-13 parts by weight of a anti-cratering agent containing a hydroxyl group at the both terminals of polyepoxide-polyoxyalkylene diamine molecule. Preferably the anti-cratering agent is a polymer represented by the formula(2), wherein R is represented by the formula(2-a); and n is 0-3.

Description

High weatherability regin compositions for electrodeposition coating

The present invention provides a main resin comprising an aliphatic polyol and a polyepoxide or a main resin comprising an aliphatic polyol and an aromatic polyol and a polyepoxide; Blocked aliphatic or cycloaliphatic isocyanate curing agents; And it relates to a resin for electrodeposition paints applicable to the undoped system comprising a cratering additive comprising a hydroxyl group at both ends of the polyepoxide-polyoxyalkylenediamine molecule. In addition, the present invention relates to a method for producing a cratering additive comprising a hydroxyl group at both ends of the polyepoxide-polyoxyalkylenediamine molecule used in the electrodeposition paint resin of the present invention. In addition, the present invention relates to a paint composition comprising the water-dispersible resin for electrodeposition paint of the present invention.

Electrodeposition is a coating method by electrophoresis and precipitation, and its importance is gradually increasing in the coating industry as compared with general coating methods such as brushes, rollers, or sprays, which have high coating efficiency, excellent corrosion resistance, and low environmental pollution. Its application is applied to many parts such as automobiles, automobile accessories, farm equipment, household goods, electrical appliances and steel furniture, but the biggest demand is the automobile-related industry, accounting for more than 80%.

The paint system currently applied to most automobiles is composed of large-mid-mid-tops. The undercoat is electrodeposition coating and subsequent subsequent coatings are spray-coated. However, such a coating system has been pointed out a problem due to the loss of the paint by spray coating and the increase of equipment cost and maintenance cost due to several baking of the coating. As one of the attempts to solve the above problems, a technique for reducing the cost consumed in subsequent coatings by baking three times a subsequent coating followed by an electrodeposition coating is being developed, but brings many problems in practice.

Midway possesses physical properties such as electrodeposition and top coat adhesion, chipping resistance and weather resistance, and to remove such midway, it is necessary to improve the properties of the electrodeposition coating film. The most concerned property due to the elimination is the adhesion with the top and the chipping resistance, as well as the adhesion with the top due to the deterioration of weather resistance. As the degree of elimination is eliminated, the electrodeposition coating layer is also affected by ultraviolet rays emitted from the outside. As the UV exposure time lasts, the electrodeposited coating film, which is relatively poor in weatherability, is choked on the surface, and thus adhesion of the top coat to the external weak impact is reduced. Therefore, in the intermediate elimination system, an electrodeposition paint resin having excellent weather resistance and good corrosion resistance and mechanical properties, which are basic properties of the electrodeposition coating film, becomes an essential condition.

When the aromatic polyol is used, the corrosion resistance is excellent, but when it is exposed to the outside, the problem that gloss reduction, color change and choking occur easily in a short time is replaced by aliphatic polyol in part or the entire amount of the aromatic, which has good corrosion resistance and weather resistance. Can be formed, the use of blocked aliphatic or cycloaliphatic polyisocyanate as a curing agent can improve the weather resistance and level improvement of the coating film, and both ends of the polyoxyalkylenediamine-polyepoxide molecule The present invention has been completed by discovering that the inclusion of a cratering-resistant additive having a hydroxyl group in the present invention improves the scratch resistance and improves the adhesion / chipping resistance to the top coat. Accordingly, an object of the present invention is to provide a resin for electrodeposition paint having high weather resistance and excellent leveling property.

It is still another object of the present invention to provide a method for producing a cratering additive comprising a hydroxyl group at both ends of a molecule of the polyoxyalkylenediamine-polyepoxide structure used in the electrodeposition paint resin of the present invention. .

25 to 35 parts by weight of a main resin including an aliphatic polyol and a polyepoxide; 12 to 16 parts by weight of a curing agent comprising a trivalent or higher polyhydric alcohol and an aliphatic or alicyclic isocyanate blocked with mono or dihydric alcohol; And it relates to a water-dispersible resin for electrodeposition paint comprising 1 to 13 parts by weight of a cratering additive containing a hydroxyl group at both ends of the molecule of polyepoxide-polyoxyalkylenediamine.

If the main resin content is less than 25 parts by weight, the water dispersion stability is lowered, and if it exceeds 35 parts by weight, coating film properties such as coating appearance and corrosion resistance is poor. If the content of the curing agent is less than 12 parts by weight, there is a problem that the degree of curing is lowered, and the corrosion resistance is reduced, and when the content of the curing agent exceeds 16 parts by weight, the coating film appearance drops. If the content of the cruttering additive is less than 1 part by weight, the effect of the control of the cruttering is inferior.

The polyepoxide that can be used for the main resin polymerization in the present invention includes bisphenol type, aliphatic, glycidyl ester type, phenolloblock type, cresol type and the like. Preferably, diglycidyl ether (DGEBA) of bisphenol A of formula (1), wherein the average n value is 0.14 to 3.1, and the epoxide equivalent weight (EEW) is 100 to 700.

[Formula 1]

The polyols usable in the present invention may be used alone with aliphatic polyols, and may be used in combination with one or two of aromatic polyols. The aliphatic polyol includes an aliphatic polyol having 2 to 12 carbon atoms with or without a double bond. Preferably diethylene glycol, trimethylol propane, butanediol, neopentyl glycol, hexanediol, tetramethylene glycol or polycaprolactone polyol and the like.

In addition, the aliphatic polyol has a molecular weight of 500 to 2100 and a solid content of the main resin of 10 to 35% by weight, and provides excellent durability and coating properties within the above range.

Aromatic polyols usable in the present invention may include aromatic polyols known in the art as coating monomers, preferably bisphenol A or ethoxylated bisphenol A.

The polymerization ratio of the polyepoxide and the aliphatic polyol may be applied in the range of 1: 0.65 to 1: 0.85 in an equivalent ratio. If the aliphatic polyol is less than 1: 0.65, there is no effect of improving weather resistance, while if the aliphatic polyol is more than 1: 0.85, problems of coating film properties such as corrosion resistance are caused.

In the selection of the curing agent, in consideration of corrosion resistance, aromatics such as TDI (toluene diisocyanate), MDI (methane diphenyl diisocyanate), polymeric MDI, xylene diisocyanate, or TMXDI (tetramethyl xylene diisocyanate) are generally considered as isocyanates. Although a curing agent may be used, such a raw material has a structure that is vulnerable to weather resistance, and in the present invention, an aliphatic or alicyclic isocyanate is applied to improve weather resistance. Isocyanates applicable to the water-based dispersion composition for coatings of the present invention include aliphatic isocyanates having 3 to 12 carbon atoms and alicyclic isocyanates of 5- or 6-membered rings. Preferably, there are IPDI (isophorone diisocyanate), HDI (hexamethylene diisocyanate), hydrogenated MDI or isocyanurate (ISOCYANURATE) and the like. Most preferably, IPDI is applied. The alicyclic IPDI has almost no corrosion decay when forming the coating film compared to the aliphatic raw materials. Also, the alicyclic polyisocyanate is different in the reaction rates of the pre- and post reactions because the surrounding environment in which the NCO (isocyanate) is combined is different. The difference is much higher than that (IPDI post-reaction is about one-third of the pre-reaction rate). This property enables selective blocking by the application of two or more alcohols in the manufacture of alcohol-blocked curing agents.

Alcohols applicable to the above isocyanates as blocking agents are used by mixing a common monohydric alcohol or a conventional dihydric alcohol and a conventional trivalent or higher polyhydric alcohol known to those skilled in the art. Preferred monohydric alcohols usable in the present invention include aliphatic primary alcohols having 2 to 12 carbon atoms. More preferably ethanol, n-butanol, or propylene glycol methyl ether. Preferred dihydric alcohols include saturated or unsaturated secondary alcohols having 4 to 12 carbon atoms. More preferably 1,6-hexane diol or 1,4-butylene glycol. Preferred trihydric or higher polyhydric alcohols include tertiary or higher aliphatic alcohols having 3 to 12 carbon atoms. More preferably trimethylolethane, trimethylolpropane, or glycerin.

Two or more types of trihydric or more alcohols can be mixed and used. At this time, the trihydric alcohol or more is applicable in the range of 10 to 55 equivalent% of the total blocker, more preferably 20 to 50 equivalent% can be applied, if less than 10%, oven-loss ), Water droplets, etc. are inferior in physical properties, and when it exceeds 55%, the appearance of the coating film, the film coating properties and the mechanical properties of the coating film are deteriorated. The ratio of monohydric or dihydric alcohols to trihydric alcohols may be used within the range of 9: 1 to 4.5: 5.5, in particular, the trihydric and higher alcohols may be used as described above, such as oven loss or water droplets. Complementing the physical properties and increasing the crosslinking density of the coating film is an essential element to improve the corrosion resistance that can be reduced by using an alicyclic isocyanate. However, if the amount is excessively used, corrosion resistance tends to decrease, so it should be used within the above range.

The present invention provides a cratering additive comprising a polyepoxide-polyoxyalkylenediamine comprising a hydroxy group at both ends of the molecule of the polyepoxide-polyoxyalkylenediamine.

The polyoxyalkylene diamines usable in the present invention include polyoxyalkylenediamines having a molecular weight of 300 to 3000, preferably 1000 to 2500. The polyepoxides usable in the present invention are the polyepoxides mentioned above, and are preferably polyepoxides having the structure of formula (1).

Polyoxyalkylene diamines having excellent effects on crater control are generally used, and most of the resins to which the polyoxyalkylene diamine is applied are located at the sock end. Such a structure has a good effect of controlling the cratering by rising to the top of the coating film when forming the coating film, but causes a problem in that adhesion is reduced by lowering wettability during subsequent coating.

In the present invention, in order to solve this problem, a compound containing a hydroxyl group at the molecular end of the polyepoxide-polyoxyalkylene diamine is used to relatively reduce the content of the polyoxyalkylene diamine in the cratering additive. It has the effect of controlling the crete, and improves adhesion with the subsequent coating by reducing the change of surface properties (surface energy, hydrophilicity, etc.) according to the use of additives, and terminating the resin sock end with hydroxyl-based amine ( The resin was prevented from suddenly rising to the upper part of the coating film by partially reacting with isocyanate during the bake hardening process after coating. In addition, since unreacted hydroxyl groups on the surface of the coating film can also partially react with the subsequent coating film, this results in an improvement in adhesion between the coating films.

The compound containing a hydroxyl group at the molecular end of the polyepoxide-polyoxyalkylene diamine is preferably a polymer of the formula (2).

[Formula 2]

Where

R is

Indicates,

n is 0-3.

The present invention is used in the present invention which includes hydroxyl groups at both ends of a polyepoxide-polyoxyalkyldiamine molecule after addition of an amine having a hydroxy group to the polyepoxide and polyoxyalkylene diamine mentioned above. It provides a method for producing a crater-resistant additive.

The equivalent ratio of the epoxide and polyoxyalkylenediamine used in the cratering additive according to the present invention may be applied in the range of 1: 0.3 to 1: 0.5. If the application amount of polyoxyalkylenediamine is less than 1: 0.3, the control effect of the cruttering is inferior, and if it exceeds 1: 0.5, reaction stability problems may occur. In general, polyoxyalkylenediamine-polyepoxide polymer is widely used as a creme resistance additive, but in the case of the intermediate elimination system, there is a problem in that adhesion and chipping resistance to the top are poor. Therefore, in the present invention, in order to apply a highly weathering cationic electrodeposition coating to the undoping system, an equivalent ratio of epoxide and amine is applied in the range of 1: 0.3 to 1: 0.5, and polyoxyalkylenediamine-poly containing a sufficient hydroxyl group. In order to polymerize the epoxide structure, an amine having a hydroxyl group was applied in the range of 0.8 to 1.0 relative to the epoxide equivalent. If it is less than 0.8, the adhesion and chipping resistance with the top coat are inferior, and if it is more than 1.0, the dispersion stability is poor. Examples of the amine having a hydroxy group usable in the present invention may be an amine containing at least one hydroxy group, for example, DEA (dieethanolamine) or NMEA (n-methylethanolamine), but is not limited thereto. no.

The present invention also relates to an electrodeposition paint composition comprising the above-mentioned water-dispersible resin for electrodeposition paint and pigment paste.

In the present invention, the main component constituting the pigment paste is composed of colored pigments, extender pigments, curing catalysts and pigment dispersion resins. Titanium dioxide and carbon black may be used as the coloring pigment, and the extender pigment may be aluminum silicate, talc, aluminum hydroxide, or the like. In order to disperse the pigment, an epoxy resin and bisphenol A are reacted, and a disperse resin containing a quaternary ammonium salt and a disperse resin containing a half-blocked toluene diisocyanate are used. It is preferable to use content ratio in the range of 3: 1-5: 1. If the mixing ratio is less than 3: 1, it is difficult to control the coating film rise when the solution is bathed due to the increase of the resin fraction, and if the mixing ratio is larger than 5: 1, problems such as storage stability occur. DBTO (dibutyl tin oxide) is used as a curing catalyst, and 1 to 10% by weight based on the pigment component of the pigment paste. The use of more than 10% by weight does not significantly affect the curing temperature decrease.

If the present invention will be described in detail based on the embodiment as follows, the present invention is not limited to the embodiment.

Production Example  One

Polyepoxide and aliphatic polyol polymers were prepared from mixtures of the following components.

1. Kukdo Chemical Epoxy Resin

2. Dow Chem. Polyol

3. Epoxy resin manufactured by KCC

YD-128, Tone0201, ethoxylated bisphenol A, and xylene were introduced into the reaction vessel, and then heated to 120 ° C., and then vacuum was applied to the reactor to recover xylene. After dropping propylene glycol methyl ether and BDMA (benzyl dimethyl amine), the temperature of the reaction mixture was raised to 145 ° C. Care for exotherm was maintained at this temperature for 3 hours and 30 minutes, and then cooled to 90-100 ° C. Then R9787 was added, and then the temperature of the reaction mixture was brought to 100 ° C. and maintained at this temperature for 2 hours. When the epoxy equivalent of the reaction reached around 1860, diketimine derivatives and NMEA (n-methylethanolamine) were added, and then the temperature of the reaction mixture was maintained at 110 ° C. and maintained at this temperature for 2 hours 30 minutes. Propylene glycol methyl ether was added to dilute the reaction mixture to afford the title polymer.

Production Example  2

Polyepoxide and aliphatic polyol polymers were prepared from mixtures of the following components.

1. Dow Chem. Polyol

YD-128, Tone0201, Tone0305 and xylene were introduced into the reaction vessel, and then heated to 120 ° C., and then vacuum was applied to the reactor to recover xylene. After adding propylene glycol methyl ether and BDMA (benzyl dimethyl amine) the temperature of the reaction mixture was raised to 145 ° C. Pay attention to the exotherm and keep it at this temperature for 3 hours 30 minutes and then cool it to 90 ~ 100 ℃. Then R9787 was added, and then the temperature of the reaction mixture was brought to 100 ° C. and maintained at this temperature for 2 hours. When the epoxy equivalent of the reaction reached around 1860, diketimine derivatives and NMEA (n-methylethanolamine) were added, and then the temperature of the reaction mixture was maintained at 110 ° C. and maintained at this temperature for 2 hours 30 minutes. Propylene glycol methyl ether was added to dilute the reaction mixture to afford the title polymer.

Comparative Production Example  One

Conventional resins were prepared from mixtures of the following components.

YD-128, bisphenol A, ethoxylated bisphenol A, and xylene were introduced into the reaction vessel, and then heated to 120 ° C., and then vacuum was applied to the reactor to recover xylene. Propylene glycol methyl ether and BDMA (benzyl dimethyl amine) were added dropwise and the temperature of the reaction mixture was raised to 145 ° C. The reaction was held at this temperature for 3 hours and 30 minutes while being cautious of exotherm and then cooled to 90-100 ° C. Then R9787 was added, and then the temperature of the reaction mixture was brought to 100 ° C. and maintained at this temperature for 2 hours. When the epoxy equivalent of the reaction reached around 1860, diketimine derivatives and NMEA (n-methylethanolamine) were added, and then the temperature of the reaction mixture was maintained at 110 ° C. and maintained at this temperature for 2 hours 30 minutes. Propylene glycol methyl ether was added to dilute the reaction mixture to afford the title polymer.

Production Example  3

The alicyclic polyisocyanate blocked with polyfunctional alcohol and monofunctional alcohol was prepared from the following reaction mixture.

IPDI (isophorone diisocyanate), MIBK and DBTDL were put into a reaction vessel and heated to 50 ° C. Butyl carbitol was added slowly to the reaction vessel, taking care not to let the temperature exceed 50 ° C. (for 1 hour 30 minutes). The reaction mixture is held at 50 ° C. for 30 minutes until the NCO% remaining unreacted in IPDI is 9-10%. TMP was added dropwise while paying attention to exotherm, and the temperature was raised to 80 ° C. After maintaining at 80 ° C. for 1 hour, when NCO% became 0, MIBK was added and diluted to obtain the title compound.

Production Example  4

The polyepoxide-polyoxyalkylenediamine polymer containing a hydroxyl group was prepared from the following reaction mixture.

1. BPA type epoxide resin with 450 ~ 500 epoxide equivalent produced by KCC.

N8010 and butyl cellosolve were placed in a reaction vessel and heated to 70 ° C. to completely dissolve N8010. After confirming complete dissolution, the temperature was cooled to 60 ° C. and Jeffamine D-2000 was added to the reaction vessel. After maintaining this temperature for about 2 hours 30 minutes to 3 hours, when the epoxide equivalent weight was 2550-2610, butyl cellosolve and DEA (dieethanol amine) were added and the temperature was raised to 90 ° C. The reaction was held at this temperature for 1 hour 30 minutes. Then, lactic acid was added and deionized water was slowly added dropwise to disperse the reaction product in water to obtain the title compound.

Production Example  5

Polyepoxide-polyoxyalkylenediamine resin was prepared from the following reaction mixture.

1. BPA type epoxide resin with 450 ~ 500 epoxide equivalent produced by KCC.

N8010 and butyl cellosolve were placed in a reaction vessel and heated to 70 ° C. to completely dissolve N8010. After confirming the complete dissolution, the temperature was cooled to 60 ° C., and NMEA was added thereto. After maintaining at this temperature for about 1 hour 30 minutes to 2 hours, after confirming that the epoxide equivalent weight was 1380-1450, Jeffamine D-2000 Was added to the reaction vessel. After maintaining this temperature for about 2 hours 30 minutes to 3 hours, when the epoxide equivalent became infinity, lactic acid was added and deionized water was slowly added dropwise to disperse the reaction product in water to obtain the title compound.

Example  One

Water-dispersion resin for electrodeposition paint was prepared with the following mixture.

1. Sulfinol 104 [Surfynol 104 (Air Products)]

The main resin of Preparation Example 1 and the blocked isocyanate of Preparation Example 3 were placed in a vessel and heated to 90 ° C. After maintaining this temperature for 30 minutes, the vessel was sealed and vacuumed to recover the solvent components in the mixture. Surfactant and formic acid were added and deionized water was slowly added dropwise for 2 hours. Finally, the cratering additive of Preparation Example 5 was added to prepare the title water dispersion resin.

Example  2

Water-dispersion resin for electrodeposition paint was prepared with the following mixture.

1. Surfynol 104 from Air Products

2. KCC Products

The main resin of Preparation Example 2 and the blocked isocyanate of Preparation Example 3 were placed in a vessel and heated to 90 ° C. After maintaining this temperature for 30 minutes, the vessel was sealed and vacuumed to recover the solvent components in the mixture. Surfactant and formic acid were added and deionized water was slowly added dropwise for 2 hours. Finally, the cratering additive of Preparation Example 5 was added to prepare a water-soluble resin for the title paint.

Example  3

Water-dispersion resin for electrodeposition paint was prepared with the following mixture.

1. Surfynol 104 from Air Products

The main resin of Preparation Example 1 and the blocked isocyanate of Preparation Example 3 were placed in a vessel and heated to 90 ° C. After maintaining this temperature for 30 minutes, the vessel was sealed and vacuumed to recover the solvent components in the mixture. Surfactant and formic acid were added and deionized water was slowly added dropwise for 2 hours. Finally, the cratering additive of Preparation Example 4 was added to obtain a water-soluble resin for the coating material of the title.

Comparative Example  One

A water-dispersible resin for electrodeposition paint was prepared with the following mixture.

1.Sulfinol 104 (Air Products)

2. KCC Products

The main resin of Preparation Example 1 and the blocked isocyanate of Preparation Example 3 were placed in a vessel and heated to 90 ° C. After holding at this temperature for 30 minutes, the vessel was sealed and vacuumed to recover the solvent components in the mixture. Surfactant and formic acid were added and deionized water was slowly added dropwise for 2 hours. Finally, acrylic type of crater-resistant additive was added to obtain a water-soluble resin for the title paint.

Comparative Example 2 .

Water-dispersion resin for electrodeposition paint was prepared with the following mixture.

1. Surfynol 104 from Air Products

2. KCC Products

The main resin of Comparative Preparation Example 1 and the blocked isocyanate of Preparation Example 3 were placed in a vessel and heated to 90 ° C. After holding at this temperature for 30 minutes, the vessel was sealed and vacuumed to recover the solvent components in the mixture. Surfactant and formic acid were added and deionized water was slowly added dropwise for 2 hours. Finally, acrylic type of crater-resistant additive was added to obtain a water-soluble resin for the title paint.

Production Example  6

Pigment pastes were prepared from mixtures of the following ingredients.

121.6 parts by weight of the resin for pigment dispersion, 3 parts by weight of carbon black and 413.7 parts by weight of titanium dioxide were added to the container and mixed by stirring. 37.7 parts by weight of deionized water was added to the mixture, followed by stirring, followed by dispersing with a disperser until the dispersion particle size was 10 to 12 μm to prepare a pigment paste.

Experimental Example  One

As an example, the following components were mixed to prepare a cationic electrodeposition bath.

1197 parts by weight of the water-dispersible resin of Example 1 was added to the bath at room temperature, 1503 parts by weight of deionized water and 3 parts by weight of acetic acid were stirred. 297 parts by weight of the pigment paste of Preparation Example 6 was slowly added dropwise while stirring the bath to prepare a cationic electrodeposition bath solution.

The pH of the prepared bath solution was 6.2, and the steel plate pretreated with zinc phosphate was electrocoated for 2 minutes under a voltage of 240 volt in an electrodeposition bath having a temperature of 28 ° C. The coated film was cured for 25 minutes at oven temperature of 178 ° C.

Experimental Example  2

As an example, the following components were mixed to prepare a cationic electrodeposition bath.

1197 parts by weight of the water-dispersible resin of Example 2 was added to the bath at room temperature, 1503 parts by weight of deionized water and 3 parts by weight of acetic acid were stirred. 297 parts by weight of the pigment paste of Preparation Example 6 was slowly added dropwise while stirring the bath to prepare a cationic electrodeposition bath solution.

The pH of the prepared bath solution was 6.2, and the steel plate pretreated with zinc phosphate was electrocoated for 2 minutes under a voltage of 240 volt in an electrodeposition bath having a temperature of 28 ° C. The coated film was cured for 25 minutes at oven temperature of 178 ° C.

Experimental Example  3

As an example, the following components were mixed to prepare a cationic electrodeposition bath.

1197 parts by weight of the water-dispersible resin of Example 3 was added to the bath at room temperature, and 1503 parts by weight of deionized water and 3 parts by weight of acetic acid were stirred. 297 parts by weight of the pigment paste of Preparation Example 6 was slowly added dropwise while stirring the bath to prepare a cationic electrodeposition bath solution. The pH of the prepared bath solution was 6.2, and the steel plate pretreated with zinc phosphate was electrocoated for 2 minutes under a voltage of 240 volt in an electrodeposition bath having a temperature of 28 ° C. The coated film was cured for 25 minutes at oven temperature of 178 ° C.

Comparative Experiment  One

As a comparative example, the following components were mixed to prepare a cationic electrodeposition bath.

1197 parts by weight of the water-dispersible resin of Comparative Example 1 was added to the bath at room temperature, and 1503 parts by weight of deionized water and 3 parts by weight of acetic acid were stirred. 297 parts by weight of the pigment paste of Preparation Example 6 was slowly added dropwise while stirring the bath to prepare a cationic electrodeposition bath solution. The pH of the prepared bath solution was 6.2, and the steel plate pretreated with zinc phosphate was electrocoated for 2 minutes under a voltage of 240 volt in an electrodeposition bath having a temperature of 28 ° C. The coated film was cured for 25 minutes at oven temperature of 178 ° C.

Comparative Experiment  2

As a comparative example, the following components were mixed to prepare a cationic electrodeposition bath.

1197 parts by weight of the water-dispersible resin of Comparative Example 2 was added to the bath at room temperature, 1503 parts by weight of deionized water and 3 parts by weight of acetic acid were stirred. 297 parts by weight of the pigment paste of Preparation Example 6 was slowly injected while stirring the bath to prepare a cationic electrodeposition bath. The pH of the prepared bath solution was 6.2, and the steel plate pretreated with zinc phosphate was electrocoated for 2 minutes under a voltage of 240 volt in an electrodeposition bath having a temperature of 28 ° C. The coated film was cured for 25 minutes at oven temperature of 178 ° C.

Hereinafter, the coating properties test was performed based on the examples prepared above.

Coating property  exam

1. Peel-off test with transparent tape after cross-cut to 10ⅹ10 (1mm interval) after top coat.

2. Chipping test in the same environment after specimen storage for 4 hours in a 40 ° C. chamber.

   : (Excellent) 10 <----> 0 (bad)

3. (Excellent) ◎ <------> X (Poor)

4. Leveling: surface measurement using surtronic3 + from Taylor-Hobson

5. The coated specimen pretreated with zinc phosphate in the salt-fog machine was tested for 960 hours, and the sample coated with electrodeposited for 150 hours after peeling off with transparent tape. This is a one-sided result of delamination

6. Time taken for choking by mounting specimen on QUV313-B equipment and outdoor exposure area

-a: Time taken for choking to occur by electrodeposition coating alone

-b: Time taken for the peeling of the clear coating to occur during the cross-hatch test with a transparent tape after applying the clear coating on the electrodeposited coating

It is applied to the high weather resistance electrodeposition coating resin removal system according to the present invention exhibits excellent weather resistance and has the characteristics of maintaining the corrosion resistance of the coating film and adhesion / chipping resistance with the top coat.

Claims (7)

25 to 35 parts by weight of a main resin including an aliphatic polyol and a polyepoxide; 12 to 16 parts by weight of a curing agent comprising a trivalent or higher polyhydric alcohol and an aliphatic or alicyclic isocyanate blocked with mono or dihydric alcohol; And 1 to 13 parts by weight of a cratering additive containing a hydroxyl group at both ends of the molecule of the polyepoxide-polyoxyalkylenediamine Water-dispersible resin for electrodeposition paint containing. The water dispersion resin for electrodeposition paint according to claim 1, wherein the equivalent ratio of polyepoxide and polyol is 1: 0.65 to 1: 0.85. The water-dissipating resin for electrodeposition paint, characterized in that the critter-resistant additive is a polymer of the formula (2). [Formula 2]

In the above formula R is

Indicates, n is 0-3. Hydroxyl groups at both ends of the molecule according to claim 1 comprising reacting the polyepoxide with the polyoxyalkylene diamine in an equivalent ratio of 1: 0.3 to 1: 0.5, and then adding an amine having a hydroxyl group and then heating it. Method for producing a polyepoxide-polyoxyalkylenediamine resin comprising. The method of claim 5, wherein the amine having a hydroxy group is used in the range of 0.8 to 1.0 relative to the epoxide equivalent. A method according to claim 5, wherein the amine having a hydroxy group is diethanolamine or n-methylethanolamine. An electrodeposition paint composition comprising the water-dispersible resin for electrodeposition paint of claim 1.