KR100530907B1 - Method for preparing cationic microgel aqueous dispersion and electrodeposition coating composition containing same - Google Patents

Abstract

The present invention is to prepare a polyepoxide containing a double bond by reacting a reaction product or a compound having a double bond and an isocyanate simultaneously with a polyepoxide resin having at least two epoxy groups, and primary and secondary React with one or a mixture of amines and quaternary ammonium salts to produce a polyepoxide-amine reaction product, disperse with an acid and then produce a cationic polyepoxide-amine aqueous product, A method for preparing a cationic microgel aqueous dispersion composed of crosslinking using an unsaturated ethylenic polymerizable monomer, preferably an acrylic monomer, as a crosslinking agent, and a cationic electrodeposition coating composition containing the same. The microgel prepared according to the present invention has an excellent compatibility with the non-gelled cationic electrodeposition resin, participates in the curing reaction of the coating film, and has the advantage of easily controlling the size or degree of crosslinking of the crosslinked particles. In addition, when 1 to 20% by weight of the microgel prepared according to the present invention with respect to the resin solid content, the peeling of the corner portion was much improved.

Description

Method for preparing cationic microgel aqueous dispersion and electrodeposition coating composition containing same

The present invention is to prepare a water product of a polyepoxide-amine reaction product containing a double bond, and to prepare a cross-linking agent using a unsaturated ethylenic polymerizable monomer as a crosslinking method of preparing a water-based cationic microgel dispersion and electrodeposition containing the same. It relates to a coating composition.

Cationic electrodeposition introduces quaternary ammonium salts or sulfonium salts that can be positively charged into the resin, and they move toward the cathode in the bath where the electric field is applied.At the same time, positive charges are generated by hydroxy anions generated by electrolysis of water. Precipitating resins are precipitated as they are reduced again and they are coated on the negative electrode, that is, the subject. The precipitated resin is cured by raising the temperature, the coating of the edge portion becomes thin due to the drop in viscosity due to the temperature at the time of temperature rising. If the coating of the edge portion is thinned like this, the edge portion is easily corroded and the corrosion progresses faster than other parts, which causes more serious problems. In this case, a method of increasing the molecular weight of the resin used or increasing the amount of the inorganic pigment in the bath may be used to prevent peeling of the edge portion due to the viscosity drop, but at this time, the generated smoothness of the coating is reduced.

When cationic aqueous microgels are used in cationic electrodeposition paints, excellent edge coverage is achieved while maintaining the smoothness of the coating. U.S. Patent No. 5,096,556 and Korean Patent Publication No. 94-9035 disclose methods for mixing cationic polyepoxide-amine reaction products with polyepoxide crosslinkers and crosslinking the mixture to produce cationic microgels. have. According to these patents, the cationic polyepoxide-amine reaction product and the polyepoxide crosslinker are dispersed in a reaction medium such as water and heated to crosslink the mixture to prepare a cationic microgel dispersion. The dispersion is mixed with a non-gelling cationic resin that is electrodepositable on the negative electrode to prepare an aqueous acid solution suitable for use in electrodeposition.

The aqueous acid solution containing the microgel prepared by the above method can achieve the anti-corrosion property of the corners when forming the coating film, but the powder of the microgel dispersion during the addition of the polyepoxide used as a crosslinking agent during the preparation of the microgel. There is a possibility that acidity may drop. In other words, when the crosslinking agent reacts violently with the polyepoxide-amine reaction product, the crosslinking density of the reactant may be too high, causing precipitation of the dispersion, and in this case, the dispersion particle size of the dispersion may be too large, resulting in smoothness of the coating. Severely dropped. In addition, when the reaction between the crosslinking agent and the polyepoxide-amine reaction product does not occur sufficiently, the crosslink density in the dispersion particles may be insufficient, and thus the viscosity drop at the edge portion may not be sufficiently suppressed. Therefore, the present invention is designed to solve the above-mentioned problem.

The present invention provides a polyepoxide containing a double bond by (1) reacting a reaction product or compound having a double bond and an isocyanate simultaneously with a polyepoxide resin having at least two epoxy groups, and (2) Reacting the polyepoxide containing the double bond with one or a mixture of primary, secondary amine and quaternary ammonium salts to produce a polyepoxide-amine reaction product, and (3) the polyepoxide Dispersing the side-amine reaction product with an acid and then preparing a cationic polyepoxide side-amine aqueous product, and (4) crosslinking the aqueous product using an unsaturated ethylenic polymerizable monomer as a crosslinking agent. It relates to a method for preparing a cationic microgel aqueous dispersion. Hereinafter, the present invention will be described in detail.

A polyepoxide-amine reaction product containing a double bond is prepared, and the mixture is crosslinked by cationic microdispersion by dispersing it in a reaction medium such as water and reacting other ethylenically unsaturated polymerizable monomers with a crosslinking agent. Prepare gel dispersions. The dispersion may be mixed with a non-gelling cation resin that is electrodepositable on the negative electrode to prepare an aqueous resin dispersion. An electrodeposition method using the aqueous dispersion is also provided.

As known from Korean Patent Publication No. 94-9035, the cationic microgel can be recovered as a dry product from the aqueous dispersion by evaporation, spray drying and the like, and the dried product can be used by itself.

When the cationic aqueous microgel thus prepared is used in the cationic electrodeposition process, it is possible to obtain excellent edge coverage while maintaining the smoothness of the coating film. Since the prepared microgel is a polyepoxide-amine reaction product that is easily dispersed in the outside of the particles, the crosslinking density of the inside is easily changed depending on the composition and the content of the crosslinking agent that shows high dispersion stability. There is an advantage that can be adjusted. In addition, since most of the non-gelled cationic resin used together is a polyepoxide-amine reaction product, the cationic microgel prepared by the above method is made of the same polyepoxide-amine reaction product outside the particle so that the non-gelled cationic resin is used. In addition to excellent compatibility with the coating process after the electrodeposition process, when the mixture participates in the curing together, there is an advantage that can obtain a high cross-link density while excellent in the smoothness of the coating film.

Cationic microgel dispersions can be prepared by first introducing a double bond into the polyepoxide to disperse the cationic polyepoxide-amine reaction product in an aqueous medium. A reaction product or a compound having a double bond and a functional group capable of reacting with a hydroxy group present in the oxide is reacted with a polyepoxide, and the dispersing step is a polyepoxide-amine reaction product prepared as an acid. After neutralization, water is added at 30 to 120 ° C., preferably at 50 to 90 ° C. to prepare a cation dispersion. Typically the solids content of the resulting dispersion is 15 to 50% by weight, and the degree of neutralization is suitable for an equivalent number of salts per gram of resin of 0.20 to 1.50 milliequivalents. The acid may be an organic acid such as formic acid, acetic acid, lactic acid, as well as inorganic acids such as phosphoric acid and sulfamic acid, and a mixture of organic and inorganic acids may be used. Next, the ethylenically unsaturated polymerizable monomer which is a crosslinking agent is dripped gradually. The step is carried out at 50 ~ 100 ℃, preferably 60 ~ 90 ℃. Upon completion of the dropping of the crosslinker, the reaction is heated at 80 ° C. for about 1 to 4 hours. Upon completion of this step, the crosslinking reaction of the polyepoxide-amine reactant is terminated and the viscosity of the dispersion rises. The crosslinking degree of the crosslinked particles thus obtained is measured using a soxlet extractor. The reaction product is first dried, weighed into an extractor, and then extracted in a boiling solvent such as tetrahydrofuran for 12 hours. Subsequently, the remaining residue is dried and weighed to obtain the degree of crosslinking from the reduced amount. The reaction product obtained by the present invention remains at least 20, preferably about 60% by weight, not extracted.

The particle size of the reaction product obtained by the present invention is measured by the light scattering method, and typically a value of 30 to 500 nm, preferably 50 to 300 nm is obtained. In addition, the solids content of the reaction product is about 5 to 40% by weight.

The polyepoxides used in the preparation of the polyepoxide-amine reaction product are polymerizable materials containing at least two and preferably two epoxy groups per molecule. Polyepoxides are well known in US Pat. Nos. 2,467,171, 2,615,007, 2,716,123, and 3,053,885. Examples of preferred polyepoxides are polyglycidyl ethers of polyphenols or polyglycidyl ethers of aromatic polyols such as bisphenol A. Such polyepoxides may be prepared by ether reaction of an aromatic polyol with epihalohydrin or diepihalohydrin such as epichlorohydrin or dichlorohydrin in the presence of alkali. Examples of other polyepoxides may also be derived from novolak resins or polyphenol resins. Meanwhile, the molecular weight increase of the polyglycidyl ether of the polyhydric substance is possible by the reaction of the polyglycidyl ether of the aromatic diol with the polyol which can react with the epoxide group. Examples of applicable polyols are ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, bisphenol-A and the like.

The reactants used to introduce double bonds into these polyepoxides can be obtained by reaction of diisocyanates with active hydrogen-containing ethylenically unsaturated monomers. That is, one of two isocyanate groups in the diisocyanate is reacted with an ethylenically unsaturated monomer having active hydrogen (for example, hydroxy ethyl methacrylate) to prepare a diisocyanate-ethylenically unsaturated monomer substituted with only one side. do. Diisocyanate used in the above reaction refers to aromatic or aliphatic diisocyanate which is usually used. In addition, ethylenically unsaturated monomers containing active hydrogen include hydroxyethyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate or methacrylate. The reaction proceeds by first adding a catalyst such as diisocyanate and dibutyl tin dilaurate or triethylamine into the reactor and then slowly dropping the unsaturated monomer at 20 to 40 ° C. When the dropping is completed, the reaction is held for 1 to 6 hours. The end point of the reaction is determined by titration of the amount of isocyanate functional groups present in the reactants by conventional methods. In addition to the diisocyanate-ethylenically unsaturated monomer, a compound having a double bond and an isocyanate functional group at the same time in one molecule (for example, dimethylmethisopropylbenzyl isocyanate, dimethylmethisopropenylbenzyl isocyanate (TMI, TMI, Cytek Corporation) ) Can also be used.

The reaction of introducing the diisocyanate-ethylenically unsaturated monomer reactant into the polyepoxide is carried out by reaction between the secondary hydroxy functional group present in the polyepoxide and the isocyanate functional group present in the diisocyanate-ethylenically unsaturated monomer reactant. Proceed. The reaction process can be carried out preferably by adding the diisocyanate-unsaturated monomer reactant to the polyepoxide at an elevated temperature of 80 to 150 ° C. Subsequently, the above reaction is terminated after 1 hour to 3 hours, and the viscosity may be lowered by using a solvent free of active hydrogen such as methyl isobutyl ketone to suppress the gelation reaction due to the viscosity increase.

The reaction product is then reacted with one or a mixture of primary, secondary amine and quaternary ammonium salts to prepare a polyepoxy-amine reaction product containing a double bond. The resin solids content of the polyepoxy-amine reaction product containing the double bond is typically 40 to 90% by weight.

The water product of the polyepoxide-amine reaction product containing the double bond is prepared by neutralizing the reaction product with an acid and then adding non-ionized water at 30 to 120 ° C, preferably 50 to 90 ° C.

Primary and secondary amines that react with the polyepoxide are preferably ketimines. This is mentioned in Korean Patent Publication No. 94-9035 and already disclosed in US Patent No. 4,104,147. This specification is incorporated herein by reference. Ketimine groups are hydrolyzed when dispersing the polyepoxide-amine reaction product to release primary amine groups. The ketamine derivative may be a specific polyamine that has at least one secondary amine group and can react with an epoxy group containing a primary amine group. Preferred polyamines are alkylene polyamines and substituted alkylene polyamines. Typical amines are diethylenetriamine, triethylenetetraamine and the corresponding propylene, butylene and higher alkylene amines. Primary amine groups of the polyamine compound are converted to ketimine groups by reaction with ketones. Examples of preferred ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone and the like. Particularly preferred ketones are methyl ethyl ketone and methyl isobutyl ketone. Secondary monoamines may be used in addition to the polyamine derivatives mentioned above. Examples of secondary monoamines include dimethyl amine, diethylamine, N-methylethanolamine, diethanolamine and dicocoamine. Quaternary ammonium salts can also be used and these quaternary ammonium salts are obtained by reacting the aforementioned organic and inorganic acids with tertiary amines such as dimethylethanol amine.

The reaction of the polyepoxide with primary, secondary amine or quaternary ammonium salts and mixtures thereof occurs when the amine is added to the polyepoxide. The reaction may be exothermic and may require a cooling process. In order to prevent the gelation reaction during the reaction, the amine is preferably added at a time and the epoxide functional group is used in excess of the amine. The reaction is usually carried out at 50 to 150 ° C., preferably at 70 to 130 ° C., for about 1 to 4 hours. The end point of the reaction is determined by measuring the content of epoxide functional groups in the usual manner.

The ethylenically unsaturated polymerizable monomer used as the crosslinking agent is one having at least one double bond, that is, a CH ₂ = CH <group. Examples of such monomers include vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, acrylonitrile, styrene, 1,3-butadiene, vinyl hydroxyethyl acrylate or methacrylate, hydroxypropyl acrylate Or methacrylate, glycidyl methacrylate and allyl methacrylate. Acrylic type is preferable in the above. Among them, glycidyl methacrylate and allyl methacrylate can be used to promote crosslinking, and the content thereof is 2 to 20 equivalent%, preferably 3 to 10 equivalent%.

The crosslinking reaction using the above-mentioned ethylenically unsaturated polymerizable monomer is carried out by the aforementioned method. The monomers are typically reacted using an initiator capable of generating radicals, ie catalysts or azo compounds of the peroxide type. Examples of suitable initiators are 2,2'-azobisisobutyronitrile, group consisting of 2,2'-isozo-2-methylbutyronitrile, ammonium persulfate, sodium persulfate, bis (2-ethylhexyl) In the form of peroxydicarbonate, t-butyl pulpvalate, t-butyl hydroperoxide, dibenzoyl peroxide or a mixture of such initiators with reducing agents such as alkali metal sulfites, hyposulfite and sodium formaldehyde sulfoxylate The group consisting of phosphorylation-reduction initiators may be used alone or in mixture of two or more thereof. Typically, chain transfer agents such as tert-dodecyl mercaptan are also used to control the molecular weight.

The microgel prepared by the above method is used in an amount of 1 to 20% by weight, preferably 2 to 15% by weight, based on the weight of the resin solids of the ungelled cationic resin water dispersion.

Examples of ungelled cationic resins are the amine salt groups—the acid-solubilization reaction products of polyepoxides with primary or secondary amines known from US Pat. Nos. 3,962,165, 3,947,358, 3,975,346 and 4,001,156. Containing resin. Typically these amine salt group-containing resins are used with blocked polyisocyanate curing agents. The isocyanates can be reacted with the polyepoxide-amine resin by blocking completely or partially blocking as mentioned in US Pat. No. 4,031,050. The non-gelling cationic resin is usually present in the electrodepositable resin dispersion in an amount of 60 to 90% by weight based on the resin solid content. The resin dispersion may contain a suitable organic solvent as a flocculating solvent. Preferred examples of these flocculating solvents include isopropanol, butanol, 2-ethylhexanol, isophorone, 2-butoxy ethanol, butyl carbitol, hexyl carbitol, ethylene and propylene glycol. The content of the flocculant solvent is preferably about 0.1 to 10% by weight based on the total weight of the resin dispersion.

The aqueous product prepared by the above method may include a pigment paste or various additives as necessary. For example, the pigment paste may include iron oxide, talc, lead oxide, as well as pigments having a color such as cadmium yellow, cadmium red, and chromium yellow. Conventional types such as strontium chromium, carbon black, coal powder, titanium dioxide, barium sulfate and the like may be used. Additives include surfactants, wetting agents or curing catalysts. The above-mentioned additives are usually present in the dispersion in an amount of 0.01 to 3% by weight based on the resin solids. The pigment content in the aqueous product is usually represented by a pigment to resin ratio, which is used within the range of 1: 1 in the 0.02 range.

When the aqueous dispersion is used for electrodeposition, the aqueous dispersion is placed in contact with the electrically conductive cathode and the electrically conductive anode, with the surface to be painted as the cathode. The adhesive film of the coating composition becomes a cathode when a sufficient voltage is given between the electrodes after contact with the aqueous acid solution. Electrodeposition conditions are generally similar to those for depositing other types of coatings, and the voltage used may vary. For example, voltages as low as 1 volt can be as high as thousands of volts but are typically between 50 and 500 volts. The current density is usually 0.05 to 0.5 amp / m ² and this amount tends to decrease as the electrodeposition proceeds, since an insulating film is formed on the electrode surface to hinder the flow of current. The coating compositions of the present invention can be used on a variety of electrically conductive substrates, in particular metals such as steel, aluminum, copper, magnesium and the like and materials coated with conductive carbon. After the electrodeposition coating, it is usually cured by heat treatment at a temperature of about 90 to 260 ° C. for about 1 to 40 minutes.

The following examples illustrate the invention but should not limit the invention to these details.

Example 1

This example is the preparation of the diisocyanate-acrylic monomer reactants used in the synthesis of the microgels mentioned in the present invention. The diisocyanate-acrylic monomer reactant is prepared from a mixture of the following components.

TABLE 1

Toluene diisocyanate, methyl isobutyl ketone and dibutyl tin dilaurate were introduced into the reactor and maintained at 20 ° C. Then hydroxyethyl methacrylate is slowly added dropwise. The reaction is exothermic and the reactor temperature does not exceed 40 ° C. When the dropping is completed, it is left for 6 hours without heating of the reactor and the content of the isocyanate functional group in the reactant is titrated to terminate when the value reaches the theoretical value. The solids content of the intermediate product thus obtained is 90%.

Example 2

This example illustrates the preparation of the polyepoxide-amine reactants used in the synthesis of cationic microgels from the diisocyanate-acrylic monomer reactants described in Example 1 above. The polyepoxide-amine reactant is prepared from a mixture of the following components.

TABLE 2

Diglycidyl ether of bisphenol A with epoxy equivalent 188, commercially available from ¹ Shell Chemical Co.

² Benzylaminotrifluoroborane commercially available from Air Products

Diketimines derived from ₃ diethylenetriamine and methyl isobutyl ketone (73% solids in methyl isobutyl ketone)

Epicoat 828, bisphenol-A is injected into the reaction vessel and heated to 140 ° C. A solution in which anchor 1040 is dissolved in N-methyl-2-pyrrolidone is added and the reaction mixture is heated to 150 ° C. The reaction mixture is left to stand for 30 minutes and then the average epoxy equivalent is measured by titrating the epoxy functional groups and maintained until 660 is obtained. The reaction mixture is then cooled to 125 ° C. and methyl isobutyl ketone is injected at once. The diisocyanate-acrylic monomer reactant of Example 1 was then slowly added while maintaining the reaction mixture at 120 ° C. After the addition is completed, the mixture is maintained at 120 ° C. for 2 hours and 2-butoxyethanol is added at once to cool to 90 ° C. Then, titetimine and N-methylethanolamine are added at a time and maintained for 2 hours. This produces an intermediate having a solids content of 63.2%.

Example 3

This example illustrates the preparation of an aqueous cationic dispersion used to prepare microgels from the polyepoxide-amine reactants described in Example 2. The aqueous dispersion is prepared from the following mixture.

TABLE 3

The polyepoxide-amine reaction product of Example 2 is placed in a reactor and heated to 50 ° C. Then acetic acid is slowly added and stirred for about 30 minutes. Then add the first deionized water and stir again for 30 minutes and then add the second deionized water. The final water dispersion has a solids content of 30% and a particle size of less than 50 nm.

Example 4

This example shows the synthesis of a cationic microgel dispersion by adding an ethylenically unsaturated polymerizable monomer from the cationic polyepoxide-amine aqueous product described in Example 3. The cationic microgel dispersion is prepared from the following mixture.

TABLE 4

The polyepoxide-amine aqueous product and the deionized water of Example 3 were placed in a reactor and heated up to 80 ° C. First, methyl methacrylate, butyl acrylate, styrene, butyl methacrylate, and 2,2'-azobisbutyronitrile are mixed well and then slowly added dropwise to the polyepoxide-amine aqueous product over 3 hours. The reaction may be exothermic and should be cooled as appropriate. The reaction mixture is then cooled to room temperature while maintaining for about 2 hours until the reaction is complete to obtain a cationic microgel dispersion having a solids content of 20% and a particle size of 100 nm.

Example 5

This example shows a reaction for increasing the crosslinking reaction of the cationic microgel dispersion described in Example 4. It is prepared by the following mixture, characterized by mixing and using allyl methacrylate in the acrylic monomer used in the microgel reaction.

TABLE 5

Example 6

This example is the same as Example 5 except for using glycidyl methacrylate together to enhance the crosslinking reaction in Example 5 mentioned above. The reaction is prepared from the following mixture.

TABLE 6

Example 7

This Example shows the manufacturing method of the non-gelled cationic main resin which is a component of a cationic electrodeposition paint.

TABLE 7

¹ Product of Koryo Chemical Co., Polyepoxide, Molecular Weight 960

² Product of Korea Chemical Co., Ltd., polyepoxide, molecular weight 1300

³ Daicel's products, polycarbonate polyols, molecular weight 500

⁴ Dow's product, aromatic diluent

⁵ Air Products, Inc. products with 73%, diethylenetriamine dissolved amine in methyl isobutyl ketone as a decade thymine blocked by the methylisobutyl ketone solution

⁶ Curing agent synthesized by the following method (solid content 85%)

Into a 1 L reaction vessel equipped with a stirrer, thermometer, cooler and H type separator, the above-mentioned amounts of polyepoxides N8010, N8020 and polycarbonate polyols and xylene are heated and heated to 210 ° C. While maintaining at this temperature for about ten minutes, about 70 grams of xylene were distilled out by the H-type separator, and then held for 30 minutes, then cooled to 150 ° C., benzyldimethylamine catalyst was added, and the temperature was raised to 180 ° C. for about 4 hours. React. When the theoretical epoxy equivalent is reached, it is cooled to 80 ° C again, dilution solvent, diketamine, and N-methylethanolamine are added and reacted at 120 ° C for about 2 hours. Once the theoretical epoxy equivalent and amine number have been reached, cool to 80 ° C and add hardener. The solvent was removed again in vacuo at 100 ° C., and then hydrolyzed ketimine group by adding lactic acid, an emulsifier and a small amount of water. This is cooled to room temperature again and the remaining deionized water is added to disperse to prepare a water dispersion resin having a solid content of about 40%.

The curing agent used in the preparation of the non-gelled polyepoxy-amine water dispersion resin is prepared by the following method.

Reactant parts by weight

Toluene Diisocyanate ¹ 320.0

2-butoxyethanol 260.5

Dibutyltin Dilaurate 3.2

Methyl Isobutyl Ketone 114.6

1,2,3-trimethylol propane 65.7

¹ 2,4-toluene diisocyanate / 2,6-toluene diisocyanate = 8/2

Toluene diisocyanate, dibutyl tin dilaurate, methyl isobutyl ketone and the like are added to a 1 L reaction vessel equipped with a stirrer, a thermometer, and a cooler, and the temperature is raised to 80 ° C, followed by dropwise 2-butoxy ethanol. After holding for 2 hours at this temperature, the NCO content is titrated and when this value reaches 30%, 1,2,3-trimethylol propane is added. After reacting for about 2 hours, the NCO content is titrated again and the reaction is terminated when this value reaches zero.

Example 8

This Example shows the manufacturing method of the resin for dispersing for manufacturing the pigment paste which is a component of a cationic electrodeposition paint, It is manufactured by the following mixture.

Reactant parts by weight

Epicoat828 ¹ 171.7

Bisphenol-A 69.5

Triton X-100 ² 28.2

Xylene 100.0

Anchor 1040 ³ 1.0

N-methyl-2-pyrrolidone 10.0

Methoxy-2-propanol 100.0

KT-24 ⁴ 95.0

Acetic acid 20.0

¹ Shell Chemicals Epoxy Resin

² Nonionic Emulsifiers of Alkyl Allyl Polyether Alcohols

³ Air Products, Trifluoroamine Catalysts

⁴ , 73% solution of diethylenetriamine, product of Air Products, dissolved in methyl isobutyl ketone as diketamine blocked by methyl isobutyl ketone

Insert EPON 828, Triton X-100 and xylene into a reaction vessel equipped with a stirrer, thermometer, cooler and H-type separator and heat to 210 ^° C. About 70 grams of xylene are distilled off in an H-type separator while held at 210 ^° C for 30 minutes. After cooling to 160 ^° C., an N-methyl-2-pyrrolidone solution containing bisphenol-A and anchor 1040 as a catalyst was added thereto, and then heated to 180 ^° C. for 1 hour, and the epoxy equivalent was 1130. Subsequently, methoxy-2-propanol is slowly added thereto and then cooled to 80 ^° C., KT-24 is added thereto, and the temperature is further raised to 120 ^° C. and maintained. After the holding reaction, the epoxy equivalent was confirmed to terminate the reaction. The synthesized epoxy amine resin is neutralized with acetic acid at 80 ^° C. and deionized water is added. As a clear liquid, a water-dispersible resin having a solid content of 59.1% is prepared.

Example 9

This embodiment is for producing a pigment paste which is a constituent of electrodeposition paint, and is prepared by the following mixture.

Reactant parts by weight

Dispersion Resin of Example 8 40.0

Red Silicate 17.4

Surfinol104 ¹ 5.1

Carbon Block 1.2

Titanium oxide 123.0

Dibutyl Tin Oxide 5.8

Deionized Water 60.0

¹ Emulsifier of Air Products

The ingredients are mixed together in the order indicated, well stirred and then dispersed up to Hegman No. 6 with a Dispermet SL-703 (BYK) disperser. Thus obtained solid content of pigment paste is 66.3 weight%.

Comparative Example 1

This example is to prepare a comparative electrodeposition paint containing no microgel, and is prepared by the following mixture.

TABLE 8

The electrodeposition coating liquid formed by the above formulation has a solid content of 20% and a ratio of pigment to resin of 0.3: 1.0, and when it is filtered through a 400 mesh wire mesh, aggregates are not collected.

Example 10

An electrodeposition paint containing microgels was prepared using the microgel dispersion prepared in Example 4. The microgel uses 5% by weight (32 g) of the ungelled polyepoxide-amine aqueous product solids of Example 7 and the total solids content and pigment to resin ratio are prepared as in Comparative Example 1.

Example 11

Except for using Example 5, and was prepared in the same manner as in Example 10.

Example 12

Except for using Example 6, it was prepared in the same manner as in Example 10.

Example 13

Except for using 10% by weight (62g) of the content of the microgel prepared in Example 4 was prepared in the same manner as in Example 10.

Example 14

Except for using the content of the microgel prepared in Example 5 10% by weight was prepared in the same manner as in Example 11.

Example 15

Except for using 10% by weight of the content of the microgel prepared in Example 6 it was prepared in the same manner as in Example 12.

The electrodeposition paint prepared above is subjected to electrodeposition coating at a constant voltage of 240 to 360 volts on a cold rolled steel sheet (9 mm x 20 mm) surface-treated with a zinc phosphate treatment agent. The resulting coating is then washed with water and baked in an oven at 170 ° C. for 30 minutes to obtain a thickness of 20 (± 2) microns. The resulting coating was measured for 10 days after brine spraying to measure edge corrosion. Edge corrosion is assessed by recording the average number of rust spots on the edges of the steel sheet. The results are shown in Table 9 below.

TABLE 9

The microgel prepared according to the present invention has an excellent compatibility with the non-gelled cationic electrodeposition resin, participates in the curing reaction of the coating film, and has the advantage of easily controlling the size or degree of crosslinking of the crosslinked particles. In addition, when 1 to 20% by weight of the microgel prepared according to the present invention with respect to the resin solid content, the peeling of the corner portion was much improved.

Claims (7)

(1) A polyepoxide resin having at least two epoxy groups is reacted with a reaction product of a diisocyanate and an active hydrogen-containing ethylenically unsaturated monomer or a compound having a double bond and an isocyanate at the same time to contain a double bond. Preparing a polyepoxide, and (2) reacting the polyepoxide containing the double bond with one or a mixture of primary, secondary amine and quaternary ammonium salts to produce a polyepoxide-amine reaction product. (3) dispersing the polyepoxide-amine reaction product with an acid and then preparing a cationic polyepoxide-amine water dispersion, and (4) unsaturated ethylene type as a crosslinking agent. Crosslinking using polymerizable monomers, The compound having a double bond and an isocyanate group at the same time is dimethylmethisopropylbenzyl isocyanate or dimethylmethisopropenylbenzyl isocyanate, The unsaturated ethylenic polymerizable monomer, which is the crosslinking agent, is a vinyl acetate, acrylonitrile, styrene, 1,3-butadiene, or acryl-type monomer. The cationic microgel dispersion according to claim 1, wherein the polyepoxide is a polyglycidyl ether of a polyphenol or a polyglycidyl ether of an aromatic polyol such as bisphenol A. Manufacturing method. The method of claim 1, wherein the acrylic monomer is methyl acrylate, ethyl acrylate, methyl methacrylate, vinyl chloride hydroxyethyl acrylate, vinyl chloride hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl Method for producing a cationic microgel aqueous dispersion, characterized in that methacrylate, glycidyl methacrylate or allyl methacrylate. The method of claim 1, wherein in the reaction product of the diisocyanate and active hydrogen-containing ethylenically unsaturated monomer, the diisocyanate is aliphatic or aromatic diisocyanate, and the active hydrogen-containing ethylenically unsaturated monomer is hydroxyethyl methacrylate, hydroxy A process for producing a cationic microgel aqueous dispersion, characterized in that it is ethyl acrylate, hydroxypropyl methacrylate or hydroxypropyl acrylate. It consists of the cationic microgel aqueous dispersion prepared by the method of any one of Claims 1-3, 4, and an ungelled cationic resin aqueous dispersion, The microgel in the aqueous cationic microgel dispersion is 1 to 20% by weight based on the resin solid content of the non-gelling cationic resin aqueous dispersion, The non-gelling cation resin water dispersion is a cation electrodeposition resin composition, characterized in that the non-gelling polyepoxide-amine water dispersion. A cationic microgel recovered as a dry product from the cationic microgel dispersion prepared by the method of claim 1. An electrodeposition coating composition containing the cationic microgel aqueous dispersion according to claim 1.