KR20080067491A - A cationic pigment grinding resin and an electrodepositable coating composition comprising the same - Google Patents

Abstract

A cationic resin for pigment dispersion is provided to enable control of pH and hydrophilicity, and to realize excellent appearance, pigment dispersibility and shelf stability when applied to an electrodeposition coating composition. A cationic resin for pigment dispersion is a polyepoxide-amine resin comprising, in the middle of the chain, (i) an amine group neutralizable with an acid and derived from a monoepoxide-amine compound obtained from a reaction between monoepoxide and amine having at least three active hydrogen atoms, and (ii) a quaternary ammonium salt group. The polyepoxide in the polyepoxide-amine resin includes a polyglycidyl ether of polyphenol, polyglycidyl ether of aromatic polyol or modified polyepoxide resin.

Description

Cationic resin for pigment dispersion and electrodeposition coating composition containing same {A CATIONIC PIGMENT GRINDING RESIN AND AN ELECTRODEPOSITABLE COATING COMPOSITION COMPRISING THE SAME}

The present invention relates to a cationic resin for pigment dispersion and an electrodeposition coating composition comprising the same, and more particularly, to a polyepoxide-amine resin, which comprises (i) monoepoxide and three or more active hydrogens in the middle of a chain thereof. A cation resin for dispersing pigments, characterized in that it comprises an acid-neutralizable amine group derived from a monoepoxide-amine compound obtained by the reaction of an amine having, and (ii) a quaternary ammonium salt group. It relates to an electrodeposition coating composition.

Electrodeposition coating refers to a technique in which a polymer having an electric charge moves to an electrode of opposite charge under a direct current action, and a change in pH caused by decomposition of water at the electrode causes polymer precipitation to form a nonconductive coating film. The importance of these electrodeposition methods is increasing because they provide higher adhesion efficiency, significant corrosion resistance, and lower environmental pollution than non-electrophoretic means.

The initial electrodeposition began with anion electrodeposition method to paint the work acting as the anode, but more than 90% of the cars produced recently is carried out by the cation electrodeposition method that the paint is attached to the cathode. When the potential is applied, the surface of the particle of the paint must be cationized in order for the paint to be electrophoretically moved to the cathode. Currently, most electrodeposition paint resins use a system that is neutralized with an acid in the polyepoxide-amine reaction product.

The pigment dispersion resin used to introduce the pigment in the electrodeposition paint production can be stabilized so as not to precipitate the pigment component, and should be charged so that electrophoresis can occur in the electric field. Preferred pigment dispersing resins are adducts between polyepoxides and amines having a structure similar to electrodeposited main resins, and are used to cover the surface of pigments having hydrophobic properties to stabilize dispersion in aqueous media. It is good to have some hydrophobic group.

Such cationic electrodeposition pigment dispersion resins include quaternary ammonium salt group-containing resins as typically described in US Pat. Nos. 4,007,154 and 4,186,124. However, the resin disclosed in these prior arts has excellent wettability or thermal stability of the pigment due to the introduction of the quaternary ammonium salt, but has a disadvantage in that the roughness of the coating film is severe and the thickening is difficult.

In order to compensate for this, US Pat. No. 4,230,552 introduced quaternary ammonium salts of diisocyanate-amine compounds capped with alcohols having a relatively high molecular weight, such as aliphatic alkylphenols, to the pigment dispersion resin. However, this resin also did not overcome the limitation of the rough appearance of the coating film.

On the other hand, since the end of the 80s, a part of the epoxy terminal is capped with nonyl phenol, etc. to be softened, and neutralized with thiodiethanol and acid to produce a dispersion resin is known (for example, US patent Sulfonium salt-containing resins disclosed in US Pat. No. 4,715,898), and when used, an electrodeposition system having a high breakdown voltage and capable of thickening can be obtained. However, it has been reported that paints made of sulfonium salt-containing resins have poor thermal shear stability due to interactions with lead and carbon black in pigments. In addition, sulfonium salt-containing resins, when used with industrial cationic electrodeposition baths, are typically unstable to the shear forces that paint undergoes when passing through a recirculation pump, and particularly poor storage of paints containing lead compounds or carbon black. The disadvantages are revealed. In order to compensate for the above disadvantages, a mixed use of a sulfonium salt resin and a quaternary ammonium salt resin has been attempted, but this also has a rough appearance.

In the 90's, in order to compensate for the above disadvantages, a sulfonium salt-quaternary ammonium salt mixture was simultaneously produced by adding a neutralized sulfide-amine mixture to a nonylphenol-flexible epoxy resin. A method for producing a paint having improved thermal shear stability in paint has been reported (US Pat. No. 5,130,004), but it has a disadvantage in that the hydrophilicity is poor.

On the other hand, resins containing primary, secondary and tertiary amine salts as dispersion resins are known. However, they smooth the electrodeposited coating film, but do not provide satisfactory pigment dispersibility, and also have the disadvantage of poor stability in the long-term storage of the electrodeposition bath, which is because the amine salts are salt groups containing protons. It is believed that this is because the proton exchange reaction during acid and storage decreases the storage stability.

However, the introduction of appropriate hydrophilic groups into these amine salts can improve the pigment dispersion and storage stability of these resins. In other words, by introducing a hydrophilic group, since the steric stabilization effect is imparted to the resin for dispersion, pigment dispersion and storage stability can be improved. Therefore, in producing resin for pigment dispersion, what kind of hydrophilic group is introduced into resin for dispersion is an issue. For example, Austrian Federal Patent Nos. 365,214 and 380,264 disclose resins for epoxy resin pigment dispersions containing oxazolidine groups. The oxazolidine group of this resin has a problem of poor shelf life in the bath solution, but it is known that the pigment dispersibility is good and actually used.

As described above, in the pigment dispersion resin for electrodeposition paint, development of a resin having both excellent appearance, excellent pigment dispersibility and excellent storage stability has been demanded.

The present invention is to solve the problems of the prior art as described above, the object of the present invention, it is possible to control the pH and hydrophilicity, when applied to the electrodeposition coating composition, excellent appearance, excellent pigment dispersibility and It is to provide a cationic resin for pigment dispersion exhibiting excellent storage stability and an electrodeposition coating composition comprising the same.

According to one aspect of the invention, a polyepoxide-amine resin, derived from a monoepoxide-amine compound obtained by the reaction of (i) a monoepoxide and an amine having at least three active hydrogens in the middle of the chain thereof There is provided a cationic resin for pigment dispersion, comprising an acid neutralizable amine group, and (ii) a quaternary ammonium salt group.

According to another aspect of the present invention, there is provided a pigment paste comprising a cationic resin for pigment dispersion according to the present invention.

According to another aspect of the present invention, there is provided an electrodeposition coating composition comprising a cationic resin for pigment dispersion according to the present invention.

Hereinafter, the present invention will be described in more detail.

The cationic resin for pigment dispersion of the present invention is basically a polyepoxide-amine resin. The polyepoxide in the polyepoxide-amine resin usually has an epoxide equivalent of 180 to 2000, and preferably has two or more 1,2-epoxide groups. Examples of preferred polyepoxide resins include polyglycidyl ethers of polyphenols or polyglycidyl ethers of aromatic polyols such as bisphenol-A. Such polyepoxide resins can be prepared by ether reaction of epihalohydrin or diepihalohydrin such as epichlorohydrin or dichlorohydrin with an aromatic polyol in the presence of alkali. Another example of the polyepoxide resin is a modified polyepoxide resin derived from, for example, a noblock resin or a polyphenol resin. On the other hand, the molecular weight of the polyglycidyl ether of the polyhydric material may be increased by the reaction of the polyglycidyl ether of the aromatic diol with the polyol capable of reacting with the epoxide group. Examples of the polyol applicable at this time include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, bisphenol-A and the like.

Examples of monoepoxides usable in the present invention include monoepoxides of the general formula (1).

[Formula 1]

In Formula 1, R 1 is hydrogen or methyl; R2 is hydrogen, alkyl including cycloalkyl (preferably C1-C18 alkyl), aryl (preferably C6 to C18 aryl), or substituted alkyl that does not interfere with the reaction of the monoepoxide with the amine, or Aryl group. Examples of substituted alkyl or aryl groups that do not interfere with the reaction of the monoepoxide with the amine include the followings.

[Wherein R 3 is alkyl containing cycloalkyl (preferably C 1 -C 18 alkyl) or C 6 -C 18 aryl.]

Examples of suitable monoepoxides are glycidyl esters of monoacids, glycidyl acetate, glycidyl butyrate, glycidyl palmitate, glycidyl laurate, and glycidyl esters sold under the trade names CARDURA E. ; Butyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, p- (tert-butyl) phenyl glycidyl ether and the like which are glycidyl ethers of alcohols or phenols.

As the amine having three or more active hydrogens reacting with the monoepoxide, diamines, triamines or tetramine compounds may be used alone or in combination, more preferably diamines or triamines. Examples of preferred amines include ethylene diamine, hexamethylene diamine, tetrapentamethylene diamine, pentamethylene diamine, 2-methylpentamethylene diamine, polyoxy alkylene diamine, diethylenetriamine, aminoethylethanolamine, triethylenetetraamine, Or mixtures thereof.

In preparing the monoepoxide-amine compound by reacting the monoepoxide with an amine having three or more active hydrogens, two or more (preferably two) active hydrogens are mono It remains in the epoxide-amine compound. When the resin for dispersing the pigment is prepared using a monoepoxide-amine compound having two or more active hydrogens, the polyepoxide in which the amine group is located in the middle of the chain by chain extension reaction with the polyepoxide resin during the manufacturing process Will form a side-amine. For this reason, the molecular weight of resin for pigment dispersion can be adjusted, and hydrophilicity is strengthened more. Furthermore, the monoepoxide is located in the side chain to impart hydrophobicity to the resin and at the same time to impart a steric hindrance effect to the pigment paste, resulting in more excellent pigment dispersibility and stability. In addition, the monoepoxide located in the side chain gives flexibility to the pigment dispersion resin so as to exhibit a smoother appearance of the coating film.

In addition, when the pigment paste is prepared, an additional acid may be added to neutralize the amine group, thereby enhancing hydrophilicity, and thus, the pH of the pigment paste may be adjusted to an appropriate level.

The quaternary ammonium salt group introduced in the middle of the chain of the pigment dispersion resin of the present invention is formed by the reaction of the epoxide group of the polyepoxide-amine with a tertiary amine salt, through a chain extension reaction in the middle of the chain of the resin. Is introduced.

The tertiary amine salt is formed by urethane-bonding the hydroxy group of the dialkylalkanolamine with the diisocyanate and neutralizing it with an acid. In this case, as the dialkyl alkanolamine, a dialkyl alkanolamine represented by the following formula (2) may be used. Preferably, dimethylethanolamine, dimethylpropanolamine, diethylethanolamine, diethylpropanolamine, and mixtures thereof. One selected from the group consisting of can be used.

[Formula 2]

In Formula 2, R 1 is an aliphatic hydrocarbon having 2 to 4 carbon atoms, and R 2 is an aliphatic hydrocarbon having 2 to 6 carbon atoms.

Examples of the diisocyanate which forms a urethane bond with the hydroxy group of the dialkyl akanolamine include methylene diphenyl diisocyanate, toluene diisocyanate, isopron diisocyanate and the like, and more preferably methylene diphenyl diisocyanate is used.

There is no particular limitation on the type of acid used to form the quaternary ammonium salt, preferably organic carboxylic acid, more preferably lactic acid, acetic acid, propionic acid, butyric acid, dimethylpropionic acid, dimethylbutanoic acid, formic acid and glycolic acid At least one organic carboxylic acid selected from the group consisting of is used.

The dialkylalkanolamine and the diisocyanate preferably react with a dialkylalkanolamine: diisocyanate in a molar ratio of 1: 2. The tertiary amine salt formed by this reaction reacts with the epoxide of the polyepoxide-amine to form quaternary ammonium salts and at the same time chain lengthens to increase the molecular weight of the chain, as a result, the quaternary ammonium salts disperse the pigment. It is located in the middle of the resin chain.

The ratio of the acid-neutralizable amine group (i) and the quaternary ammonium salt group (ii) contained in the resin of the present invention is not particularly limited thereto, but may be used for dispersing the pigment in consideration of the molecular weight distribution and the degree of hydrophilicity of the polymer. It is appropriate that they are each 0.25 to 1.4 milliequivalents per gram of resin. If the content is less than the appropriate amount, the wettability of the pigment is poor, and if it is too large, a water-soluble vehicle is formed, which may result in poor wettability of the pigment. In view of the smoothness of the resulting coating film and stability of the pigment paste and the electrodeposition coating composition, the amine group (i) which is neutralizable with the acid to which the monoepoxide has been added is preferably 0.01 to 1.3 milliequivalents per gram of pigment dispersion resin. The quaternary ammonium salt group (ii) is contained in an amount of 0.01 to 1.2 milliequivalents.

The resin for dispersing the pigment of the present invention exhibits excellent dispersibility in dispersing the pigment due to the structural properties in which the amine group (i) and the quaternary ammonium salt group (ii), which are neutralizable with an acid as described above, are located in the middle of the chain. At the same time, excellent stability can be imparted to the pigment paste and electrodeposition coating composition containing the same.

The pigment paste of this invention is manufactured by grind | pulverizing various pigment components with the resin for pigment dispersion of this invention. Electrodeposit paints usually cause shear instability problems depending on the pigment applied, and the resin for pigment dispersion of the present invention helps to stabilize it.

Pigment components that can be used in the production of pigment pastes include titanium dioxide, antimony oxide, zinc oxide, barium carbonate, calcium carbonate, aluminum silicate, silica, magnesium carbonate and / or magnesium silicate, cadmium yellow, cadmium red, carbon black, Colored pigments such as phthalocyanine blue, chrome yellow, toluidine red and hydrated iron oxide can also be used. In particular, carbon black often shows poor heat storage stability due to small particle size and strong hydrophobicity, and the resin for pigment dispersion of the present invention may stabilize it. In addition to the pigment component and the resin component for pigment dispersion, the pigment paste may optionally contain components such as wetting agents, surfactants and antifoaming agents.

Grinding is generally done until the pigments are reduced to the desired size, preferably using ball mills, sand mills, continuous mills, etc., until they are wet or dispersed by the grinding colorant. Usually the particle size of the pigment after milling is 10 microns or less, 6-8, preferably 7-8, with a Hegman gauge.

Dispersion of the pigment component is generally carried out in an aqueous dispersion of the colorant. Since the amount of water present in the aqueous dispersion must be sufficient to form a continuous phase, the electrodeposition paint generally contains 30 to 70% by weight solids. If the amount of water is too small, the viscosity may be continuously increased, on the contrary, when too much water is used, the viscosity at the time of mixing is too low to reduce the effective capacity of the dispersion. The weight ratio of pigment component: resin solid content for pigment dispersion in the dispersing step is usually maintained in the range of about 1.5: 1 to 10: 1, preferably in the range of 3: 1 to 6: 1.

Generally, combining the cationic electrodeposition resin known in the art for the cationic electrodeposition and the pigment paste of the present invention yields the electrodeposition coating composition of the present invention. In most cases the final electrodeposition coating composition has a pigment / binder ratio of about 0.1 to 0.5. In the electrodeposition process, a bath solution containing 5 to 25% by weight of pigments and resin solids is generally used. The final electrodeposition coating composition is used in addition to pigment paste and electrodeposition main resin, as a sub resin, a solvent, an antioxidant, It may further include a surfactant and the like. The aqueous electrodeposition coating composition is placed so as to be in contact with the electrical cathode and the anode, respectively, and then subjected to electrodeposition under a DC voltage ranging from several V to several hundred V, and a current density of 0.25 to 15 A / ft ² . After electrodeposition, a completed coating film is obtained through a washing process and a curing process. In this case, the curing process is usually performed at a temperature of 150 to 200 ° C. for 15 to 60 minutes.

The electrodeposition paint composition of the present invention includes a capped isocyanate as a curing agent, wherein the capped isocyanate is an organic polyisocyanate and caps the isocyanate group such that the resulting capped isocyanate group is stable to active hydrogen at room temperature but reacts with active hydrogen at high temperature. Polyisocyanate reacted with the compound.

In preparing the capped polyisocyanate curing agent, aliphatic or aromatic polyisocyanates including cycloaliphatic may be used, and representative examples thereof include 2,4- or 2,6-toluene diisocyanate and mixtures thereof, p-phenylene diisocyanate, tetra Methylene or hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisosanate, isophorone diisocyanate, diphenylmethane-4,4'-diisosanate and polymethylene polyphenyl isocyanate. . Higher polyisocyanates such as triisocyanate may also be used. Alternatively triphenylmethane-4,4 ', 4 "-triisocyanate may be used. In addition, NCO-prepolymers such as reaction products of polyisocyanates with polyols such as neopentylglycol and trimethylol propane, and reaction products of polymer polyols such as polycaprolactone diols and triols may also be used.

On the other hand, the capped polyisocyanate curing agent can be used in two ways. Firstly, it can be used in fully capped form, ie in the form of free isocyanate remaining, in which case it is present as a two-component resin system through blending with the epoxy backbone. Secondly, it may be made into a one-component resin by reacting with an active hydrogen group in the epoxy polymer backbone after only a portion is capped. In terms of the stability of the resin, the latter case where the epoxy main chain and the urethane curing agent form a chemical bond may exhibit more stable water dispersion stability, but the partially capped curing agent component is very reactive and stored for a long time in a stable state. There is also a disadvantage in that it is not easy to cause various problems in terms of production stability. On the other hand, a curing catalyst such as tin catalyst is usually present in the curing agent component. Examples include dibutyl tin dilauryl and dibutyl tin oxide, and they are preferably present in an amount of about 0.05 to 1% by weight based on the weight of the total resin solid.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, these examples are only to aid the understanding of the present invention, and the present invention is not limited thereto.

Preparation Example 1 Preparation of Monoepoxide-Amine Compound

A monoepoxide-amine compound was prepared from the components shown in Table 1 below.

TABLE 1

[CARDURA E10: Monoepoxy commercially available from Shell Chemicla co.]

2-methylpentamethylene diamine and 2-butoxyethanol were put into a reactor, and the temperature was raised to 70 ° C while slowly stirring. Monoepoxy (CARDURA E10) was added slowly while maintaining the temperature at 70-80 ° C. After the addition was completed, the reaction mixture was warmed to 100 ° C. and stirred for 2 hours to prepare a monoepoxide-amine compound.

Preparation Example 2 Preparation of Monoepoxide-Amine Compound

A monoepoxide-amine compound was prepared from the components shown in Table 2 below.

TABLE 2

Diethylenetriamine and 2-butoxyethanol were put into a reactor, and the temperature was heated up to 70 degreeC, stirring slowly. 2-ethylhexyl glycidyl ether was slowly added while maintaining the temperature at 70-80 ° C. After the addition was completed, the reaction mixture was warmed to 100 ° C. and stirred for 2 hours to prepare a monoepoxide-amine compound.

Preparation Example 3 Preparation of a Chain Extension Quaternizing Agent

A tertiary amine salt compound was prepared as a chain extending quaternization agent from the components shown in Table 3 below.

TABLE 3

[PAPI2940: Polymeric Methylene Diphenyl Diisocyanate Commercially Available from Dow Chemical Co.]

PAPI2940 and methyl isobutyl ketone were placed in a reaction vessel and dimethylethanolamine was added. At this time, an exothermic reaction occurred. The reaction mixture was raised to 80 ° C. and stirred for 3 hours. Then 2-butoxyethanol was added cooling to 60 degreeC. Acetic acid was then added and stirred at 65 ° C. for about 1 hour to synthesize a chain extend quaternizing agent.

Example 1 Preparation of Resin for Pigment Dispersion

A resin for pigment dispersion was prepared from the components shown in Table 4 below.

TABLE 4

[N8010: Diglycidyl ether of bisphenol A having an epoxy equivalent of 480 produced by KC Corporation]

After adding N8010 and 2-butoxyethanol (primary) to the reactor, the temperature was raised to 90 ° C while stirring. Then, the monoepoxy-amine compound of Preparation Example 1 was slowly added. Some fever occurred at this time. After the reaction temperature was raised to 120 ° C. and maintained for 2 hours, the reaction was maintained until the epoxy equivalent reached 1200. 2-butoxyethanol (secondary) was added when the epoxy equivalent reached 1200. The reaction mixture was cooled to 85-90 ° C., deionized water was added, and the chain extension quaternization agent of Preparation Example 3 was added. The temperature of the reaction mixture was maintained at 80 to 85 ° C. until the acid value became about 1, and 2-butoxyethanol (tertiary) was added to prepare a resin for pigment dispersion.

Example 2 Preparation of Resin for Pigment Dispersion

A resin for pigment dispersion was prepared from the components shown in Table 5 below.

TABLE 5

After adding N8010 and 2-butoxyethanol (primary) to the reactor, the temperature was raised to 90 ° C while stirring. Then, the monoepoxy-amine compound of Preparation Example 2 was slowly added. Some fever occurred at this time. After the reaction temperature was raised to 120 ° C. and maintained for 2 hours, the reaction was maintained until the epoxy equivalent reached 1300. 2-butoxyethanol (secondary) was added when the epoxy equivalent reached 1300. The reaction mixture was cooled to 85-90 ° C., deionized water was added, and the chain extension quaternization agent of Preparation Example 3 was added. The temperature of the reaction mixture was maintained at 80 to 85 ° C. until the acid value became about 1, and 2-butoxyethanol (tertiary) was added to prepare a resin for pigment dispersion.

Comparative Production Example 1-Preparation of Diquaternizing Agent

The chain extension quaternizing agent was prepared from the components shown in Table 6 below.

TABLE 6

Toluenedioisocyanate half-capped with 2-ethylhexanol, present in solvent methyl isobutyl ketone, was placed in a reaction vessel and dimethylethanolamine was added. At this time, an exothermic reaction occurred. The reaction mixture was stirred at 80 ° C. for 1 hour. An aqueous lactic acid solution and 2-butoxyethanol were then added sequentially. The reaction mixture was stirred at 65 ° C. for about 1 hour to synthesize a quaternizing agent.

Comparative Example 1-Preparation of Resin for Pigment Dispersion

A resin for pigment dispersion was prepared from the components shown in Table 7 below.

TABLE 7

[Epon 829: diglycidyl ether of bisphenol A with epoxy equivalent 188, commercially available from Shell Chemicla co.]

Epon 829 and bisphenol A were placed in a reaction vessel in a nitrogen atmosphere and heated to 150-160 ° C. to initiate an exothermic reaction. The reaction was carried out at 150 ~ 160 ℃ for 1 hour. The reaction mixture was then cooled to 120 ° C. and toluene diiocyanate half capped with 2-ethylhexanol, present in solvent methyl isobutyl ketone, was added. The temperature of the reaction mixture was maintained at 110-120 ° C. for 1 hour and then 2-butoxyethanol was added. The reaction mixture was cooled to 85-90 ° C., deionized water was added, and a quaternizing agent was added. The temperature of the reaction mixture was maintained between 80 and 85 ° C. until the acid number was about 1.

Preparation Example 4-Preparation of Dibutyltin Oxide Paste

Dibutyltin oxide paste was prepared from the ingredients shown in Table 8 below.

TABLE 8

Dibutyltin oxide was added to the pigment dispersion resin prepared in Example 1 while stirring. When the pigment content increased and the viscosity increased, deionized water (primary) was added and stirred well until the pigment content became uniform, and finally, deionized water (secondary) was added and diluted. The mixture was dispersed up to Hegman number 8 with a SL-703 (BYK) disperser.

Preparation Example 5 and Comparative Preparation Example 2-Preparation of Dibutyltin Oxide Paste

Dibutyltin oxide pastes of Preparation Example 5 and Comparative Preparation Example 2 were prepared in the same manner as in Preparation Example 4, respectively, using the resins of Example 2 and Comparative Example 1 as the resin for pigment dispersion.

Example 3 Preparation of Pigment Paste

Pigment pastes were prepared from the components shown in Table 9 below.

TABLE 9

[ASP200: Aluminum silicates available from Engelhard Corporation

Sulfinol 104: Hexininol-based wetting agent as a product of Air Product]

The pigment dispersion resin prepared in Example 1 was added and the components were added while stirring sequentially. When the pigment content increased and the viscosity increased, sulfinol 104 was added and the mixture was stirred well until the pigment content became uniform, followed by dilution with second deionized water. The mixture was dispersed to Hegman No. 6+ with an SL-703 (BYK) disperser.

Example 4 Preparation of Pigment Paste

A pigment paste was prepared in the same manner as in Example 3, except that the resin for pigment dispersion of Example 2 and the dibutyltin oxide paste of Preparation Example 5 were used.

Comparative Example 2-Preparation of Pigment Paste

A pigment paste was prepared in the same manner as in Example 3, except that the resin for pigment dispersion of Comparative Example 1 and the dibutyltin oxide paste of Comparative Preparation Example 2 were used.

Preparation Example 6-Preparation of Urethane Curing Agent

The urethane hardener used for the cationic electrodeposition resin was prepared from the components shown in Table 10 below.

TABLE 10

PAPI2940, methyl isobutyl ketone and dibutyltin dilaurate were fed to the reaction flask and heated to 30 ° C. under a nitrogen atmosphere. 2- (2-butoxyethoxy) ethanol (primary) was added slowly while maintaining the temperature at 60-65 degreeC. After the addition was complete the reaction mixture was left at 65 ° C. for 90 minutes. Trimethylol propane was then added and the mixture was heated to 110 ° C. and left at this temperature for 3 hours and 2- (2-butoxyethoxy) ethanol (secondary) was added. Infrared analysis was continued at 110 ° C until no unreacted NCO remained.

Preparation Example 7-Preparation of Cationic Electrodeposition Dispersed Resin

The cationic electrodeposition aqueous dispersion resin was prepared from the components shown in Table 11 below.

TABLE 11

[Epon 828: Diglycidyl ether of bisphenol A with epoxy equivalent 188, commercially available from Shell Chemicla co.

KT-22: A 73% solution in which diethylenetriamine is a diketimine capped by methyl isobutyl ketone as a product of Air Product.]

EPON828, bisphenol A-ethylene oxide adduct, bisphenol A and methyl isobutyl ketone were fed to a reaction vessel and heated to 140 ° C. under a nitrogen atmosphere. Benzyldimethylamine (primary) was added and the reaction mixture was exothermic to about 185 ° C. and refluxed to remove azeotropic water. The reaction mixture was cooled to 160 ° C., left for 30 minutes, then further cooled to 145 ° C. and benzyldimethylamine (secondary) was added. 145 ° C was maintained until the epoxy equivalent reached 1100-1140. After the epoxy equivalent was reached, the urethane curing agent of Preparation Example 6, KT22, and N-methyl ethanolamine were continuously added. The mixture was exothermic and then cooled to 125 ° C. After standing at 125 ° C. for 2 hours, the reaction was slowly added to the mixture of stirring formic acid and deionized water (primary) with sufficient stirring to disperse. Then, deionized water (secondary) and deionized water (third) were sequentially added to the dispersion to further dilute, and the organic solvent was removed by vacuum stripping to prepare a cationic electrodeposited aqueous dispersion resin having a solid content of 36%.

Examples 5-6 and Comparative Example 3-Preparation of Electrodeposit Coating Composition

3318 parts by weight of the aqueous product synthesized by the method of Preparation Example 7 and 3638 parts by weight of deionized water were mixed and stirred, and then slowly added 536 parts by weight of the pigment paste prepared in Examples 3, 4 and Comparative Example 2, respectively, The cationic electrodeposition coating compositions of Examples 5 to 6 and Comparative Example 3 each having a solid content of 20% were prepared.

After the electrodeposition coating composition prepared above was passed through an ultrafilter up to an amount of 20% of the initial volume, the ultrafiltrate was changed to deionized water. Thereafter, the mixture was left under stirring for one day, and then electrodeposition coating was performed at a temperature of 28 ° C. for 2 minutes at a DC voltage of 210 to 270 V. In this case, a phosphate treated steel sheet was used. The coating material coated for 2 minutes was cured at 170 ° C. for 30 minutes, and various physical property values of the coating film were measured and shown in Table 12 below.

TABLE 12

[Illuminance: Measured using Taylor-Hobson Surtronic 3+ (Cut-off values: 0.8mm)]

On the other hand, according to the method illustrated in Korean Patent Publication No. 92-931, in order to evaluate the pigment dispersibility and storage stability of the pigment dispersion resin prepared in Examples 1 to 2 and Comparative Example 1, Examples 3 to The pigment paste of 4 and the comparative example 2, or the cationic electrodeposition coating composition of Examples 5-6 and the comparative example 3 was tested, and the result shown in Table 13 was obtained.

TABLE 13

Hegman 6+ passing time during pigment dispersion: The pigment paste was dispersed by 3 kg by Dispermet SL-703 (BYK).

Heat Storage Stability: The pigment paste was stored in an oven at 60 ° C. to investigate the thermal stability. The figure shows the gelation time after heat storage of the pigment paste.

Pass through a 400 mesh screen: The paint liquid (total 2 kg) was filtered through a 400 mesh wire mesh (800 cm 2 area) one month after paint preparation. The resulting residue was dried at 110 ° C. for 3 hours and weighed.

1 g or less; ○ 1-4 g; Δ 4-10 g; × 10 g or more

Visual inspection of the cured coating film: The substrate was immersed in the coating liquid either vertically or horizontally after one month of paint preparation. Electrodeposition coating was performed as defined, and the resulting cured film was visually inspected to count the number of needle holes and aggregates per 100 cm 2.

1 or less; ○ 1 to 5; Δ 5-20; × 20 or more

As can be seen in Table 12 and Table 13, the pigment dispersion resin prepared according to the present invention had excellent pigment dispersibility, and the pigment dispersion resin itself and the pigment paste and coating composition prepared using the same were stored. Stability was excellent, resistance to pinhole and crater formation, and smooth appearance were very desirable.

As described above, according to the present invention, a pigment dispersing cationic resin exhibiting excellent appearance, excellent pigment dispersibility and excellent storage stability with respect to various pigments when applied to an electrodeposition paint, and a pigment paste and an electrodeposition coating composition comprising the same. You can get it.

Claims (12)

Polyepoxide-amine resins, acid neutralizable amine groups derived from a monoepoxide-amine compound obtained by the reaction of (i) a monoepoxide with an amine having at least three active hydrogens in the middle of its chain And (ii) a quaternary ammonium salt group. The pigment dispersion according to claim 1, wherein the polyepoxide in the polyepoxide-amine resin is a polyglycidyl ether of a polyphenol, a polyglycidyl ether of an aromatic polyol or a modified polyepoxide resin. Cationic resin. The cationic resin for pigment dispersion according to claim 1, wherein the monoepoxide is a monoepoxide of the following Chemical Formula 1.  [Formula 1]

In Formula 1, R 1 is hydrogen or methyl; R 2 is hydrogen, substituted or unsubstituted alkyl or cycloalkyl, or substituted or unsubstituted aryl group. The method of claim 1, wherein the amine having at least three active hydrogens is selected from the group consisting of ethylene diamine, hexamethylene diamine, tetrapentamethylene diamine, pentamethylene diamine, 2-methylpentamethylene diamine, polyoxy alkylene diamine, diethylenetriamine, Cation resin for pigment dispersion, characterized in that it is selected from aminoethyl ethanolamine, triethylene tetraamine, or mixtures thereof. The monoepoxide-amine compound according to claim 1, wherein the monoepoxide-amine compound obtained by reacting a monoepoxide with an amine having three or more active hydrogens has two or more active hydrogens, and the monoepoxide-amine compound and the polyepoxy An acid neutralizable amine group formed through a chain extension reaction with a side resin is located in the middle of a chain. The cationic resin for pigment dispersion according to claim 1, wherein the quaternary ammonium salt group is formed by reaction of an epoxide group and a tertiary amine salt of a polyepoxide-amine compound. The cationic resin for pigment dispersion according to claim 6, wherein the tertiary amine salt is obtained by urethane-bonding the hydroxy group of the dialkylalkanolamine with the diisocyanate and neutralizing it with an acid. 8. The cationic resin for pigment dispersion according to claim 7, wherein the acid is at least one organic carboxylic acid selected from the group consisting of lactic acid, acetic acid, propionic acid, butyric acid, dimethylpropionic acid, dimethylbutanoic acid, formic acid and glycolic acid. . The method according to claim 1, wherein the acid-neutralized amine group (i) is contained in 0.01 to 1.3 milliequivalents per gram of pigment dispersion resin, and the quaternary ammonium salt group (ii) is contained in 0.01 to 1.2 milliequivalents. Cationic resin for pigment dispersion, characterized in that. A pigment paste comprising the cationic resin for pigment dispersion according to any one of claims 1 to 9. The pigment paste according to claim 10, wherein the weight ratio of pigment component: resin solid content for pigment dispersion is 1.5: 1 to 10: 1. Electrodeposition coating composition containing the cationic resin for pigment dispersion of any one of Claims 1-9.