JP3513665B2 - Modified epoxy resin having a blocked isocyanate component and a cationic group bonded thereto, its production method and use thereof - Google Patents

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modified epoxy resin capable of electrodeposition, a method for producing the same, an electrodeposition coating composition containing the resin and a pigment dispersion paste for the electrodeposition coating.

Epoxy resins used in electrodeposition coatings open some of the epoxy groups by reaction with alkylphenols, monocarboxylic acids or hydroxycarboxylic acids,
It is a modified epoxy resin in which an ionic group is introduced by the reaction of the remaining epoxy group and amine. In order to cure the electrodeposition coating film of these modified epoxy resins, it is necessary to use a blocked polyisocyanate compound or a melamine resin as a curing agent for baking and crosslinking and curing.
However, this resin has a drawback that it requires a high baking temperature because the reactivity with the curing agent is not always satisfactory. Therefore, a self-crosslinking modified epoxy resin having a blocked isocyanate group bonded by a reaction of a secondary alcoholic hydroxyl group generated by cleavage of the epoxy ring of the modified resin and a half-blocked diisocyanate compound has been proposed as a resin for electrodeposition coating composition. . When this modified epoxy resin is also baked at a temperature of 200 ° C. or higher, which is its curing temperature,
The diisocyanate component bonded to the epoxy resin is released, and defects such as reduction in film thickness and insufficient curing are likely to occur.

Also, in the manufacture of paints, an important factor is the incorporation of pigments in the coating composition. in this case,
The pigment that should normally be used in the paint is a suitable solvent using only a part of the total amount of the vehicle that constitutes the paint.
As a dispersion paste that is dispersed in a mill used in the paint industry with diluents or other additives.
The paste is then usually mixed with the remaining amount of vehicle and any other required ingredients to obtain a coating which is a pigment dispersion composition. However, the biggest problem with such a pigment dispersion composition is that the pigment particles tend to aggregate. This agglomeration can occur during the dispersion process, the paint process, the storage process or the electrodeposition coating process. As a result, it causes unfavorable problems such as deterioration of the stability of the coating material, troubles during coating, deterioration of the appearance of the coating film, and deterioration over time. In order to suppress the aggregation of the pigment particles, it is caused by the interaction between the pigment particles, and in order to suppress this interaction, it is necessary to provide an adsorption layer on the pigment surface. It is necessary to introduce a functional group. Further, in order for the dispersed particles to exist stably in the aqueous medium, it is necessary to introduce a site having higher hydrophilicity.

Further, as a hydrophobic portion, Japanese Patent Publication No. 54-49
In 78, a method in which a half-blocked compound of a diisocyanate compound is added to a hydroxyl group in a bisphenol type epoxy resin or a hydroxyl group of an alkanolamine and introduced is used. In these methods, the urethane bond is dissociated during heat curing. Then, the isocyanate monomer is volatilized, and there is a problem that the weight loss upon heating is increased or the yellowing of the top coating film is caused.

The present invention provides a modified epoxy resin in which a cationic group and a blocked isocyanate component are bonded to the ends of the resin skeleton by reaction with each epoxy ring of an epoxy resin having a plurality of epoxy rings. .
The modified epoxy resin of the present invention is characterized in that the blocked diisocyanate component is bound to form a stable oxazolidone ring by reaction with the epoxy ring. Therefore, unlike the half-blocked diisocyanate added to the alcoholic hydroxyl group, no inconvenience due to elimination during heating and curing is observed.

According to the disclosure the present invention [0006] The present invention, bind to the resin skeleton by oxazolidone rings formed by reaction with one of the isocyanate groups of a part and a diisocyanate compound of an epoxy resin epoxy ring having a plurality of glycidyl groups And a cationic group formed by the reaction of the remaining epoxy ring and a cationic active hydrogen compound, the other isocyanate group of the bound isocyanate component is a blocking agent or an active hydrogen that does not regenerate the isocyanate group. Provided is a modified epoxy resin characterized in that it is attached to a compound.

The present invention also provides a method for producing the above-mentioned modified resin starting from an epoxy resin having a plurality of glycidyloxy groups. The method regenerates a part of the epoxy ring of the epoxy resin, a first blocked isocyanate group and a second blocked isocyanate group or an isocyanate group that is more reactive than the first blocked isocyanate group, and does not regenerate it. And reacting an asymmetric blocked diisocyanate compound having an isocyanate group respectively bonded to the second active hydrogen compound,
Then, introducing a cationic group by ring-opening reaction of the remaining epoxy ring with a cationic active hydrogen compound.

The present invention further provides an electrodeposition coating composition using the modified epoxy resin and a face powder dispersion paste for the electrodeposition coating.

Description of the Preferred Embodiments For ease of understanding, a model is used to describe the method of making the modified epoxy resin of the present invention. For convenience, the diglycidyl ether type epoxy resin (I) is selected as the starting resin,
It is assumed that bisurethane (II) whose blocking agent is a monoalcohol is selected as the asymmetric blocked diisocyanate. In the first step, the epoxy resin (I) and the asymmetric bisurethane (II) are reacted as follows.

[0010]

[Chemical 1]

In the formula, R is a residue of the epoxy resin excluding the glycidyloxy group, R ₁ is an alcohol residue of the first blocking agent, and R ₂ is an alcohol residue of the second blocking agent. .

The second step is the reaction product of the first step (III
) Is reacted with, for example, a secondary amine HN (R ″) ₂ as follows to obtain the target modified epoxy resin (IV).

[0013]

[Chemical 2]

Starting Resin The starting resin is an epoxy resin having a plurality of glycidyloxy groups. A typical example thereof is a polyphenol glycidyl ether type epoxy resin which is a reaction product of a polycyclic polyphenol compound such as bisphenol A, bisphenol F, bisphenol S, phenol novolac, and cresol novolac with epichlorohydrin. Examples of commercially available bisphenol-type epoxy resins include Epicoat 827 (epoxy equivalent 180-190), Epicoat 1001 (epoxy equivalent 450-500), Epicoat 1010 (epoxy equivalent 3000-00) sold by Yuka Shell Epoxy Co., Ltd. 4000), Epicoat 807 (epoxy equivalent 170) and the like.

In addition to polyphenol glycidyl ether type epoxy resins, polyglycidyl ethers of polyhydric alcohols such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol and polyalkylene glycol, and Polyglycidyl esters of aliphatic, alicyclic or aromatic polycarboxylic acids can also be used.

The starting resin of the present invention is a chain extension of the above-mentioned bifunctional epoxy resin by utilizing the reaction of bifunctional polyol, bifunctional polycarboxylic acid, bifunctional polyisocyanate with bifunctional polyphenol, and bifunctional polyamine. Including resin. Chain extenders that can be used for this purpose include difunctional polyester polyols, difunctional polyether polyols and bisphenols. Polyester polyols include polyester polyols obtained by the esterification reaction of polycarboxylic acids or their anhydrides with polyols, and those obtained by the polymerization reaction of lactones initiated by polyols such as polycaprolactone polyols. Those having a molecular weight of 300 to 3000 are preferable. The polyether polyol is poly (oxyethylene) glycol, poly (oxypropylene) glycol, poly (oxytetramethylene) glycol, a random or block copolymer thereof, or an adduct of bisphenol A and ethylene oxide or propylene oxide. Including, molecular weight 300-30
The range of 00 is preferable. It is also possible to use bisphenols such as bisphenol A and bisphenol F for chain extension.

The chain extension is carried out by using an aliphatic dicarboxylic acid such as succinic acid, adipic acid, azelaic acid, dodecanedioic acid and dimer acid, or an aromatic dicarboxylic acid such as phthalic acid, isophthalic acid and terephthalic acid. Good.

The chain extension reaction of a bifunctional epoxy resin with a diisocyanate compound blocked with a monoalcohol or directly with a diisocyanate compound is described by Iwakura et al. Polymer Sci. Part A-1,
4 , 751 (1966) and Sander et a.
l, J. Appl. Polymer Sci. 9 , 19
84 (1966). In this case, an epoxy resin having a plurality of oxazolidone rings in the molecular chain can be obtained.

The starting resin generally has an epoxy equivalent weight of 150 to 2,000, preferably 150 to 1,000.

First Step The first step is a reaction of a part of the epoxy resin of the starting resin with the blocked diisocyanate compound.

As the diisocyanate compound, 4,
4'-diphenylmethane diisocyanate (MDI),
Aromatic diisocyanates such as tolylene diisocyanate (TDI) and xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), fats such as isophorone diisocyanate (IPDI), 4,4′-methylenebis (cyclohexyl isocyanate) and trimethylhexamethylene diisocyanate Group and cycloaliphatic diisocyanates can be used.

Blocking agents that can be used are well known in the art, and aliphatic alcohols such as methanol, ethanol, isopropanol, n-butanol, 2-ethylhexanol, ethylene glycol monobutyl ether and cyclohexanol; phenol, nitrophenol. , Phenols such as ethylphenol; oximes such as methylethylketoxime; lactams such as ε-caprolactam. Tertiary aminoalkanols such as dimethylethanolamine, diethylethanolamine, dipropylethanolamine, and 2 such as diethylamine, dibutylamine, di-t-butylamine.
It is also possible to use a primary amine.

The reaction of Iwakura et al. Cited above is also a reaction of an epoxy resin and a blocked diisocyanate (bisurethane). In this case, the blocking agent is eliminated from both of the blocked isocyanate groups and the epoxy resin is chain extended. To do. The first step of the present invention is different from this in that only one of the first and second blocked isocyanate groups of the blocked diisocyanate should react selectively with the epoxy ring and the other should remain in block form.

A blocked diisocyanate compound having a blocked isocyanate group that remains in a block form with a blocked isocyanate group that preferentially or selectively reacts with an epoxy ring as described above is a block diisocyanate compound in which the first and second isocyanate groups are different blocking agents. Obtained by blocking. In a preferred embodiment, methanol or ethanol is used as the blocking agent for the blocked isocyanate group that reacts preferentially with the epoxy ring, and the blocking agent for the other blocked isocyanate group has 4 or more carbon atoms such as butanol and 2-ethylhexanol. Aliphatic monoalcohols, alkylphenols such as cresol and nonylphenol, glycol monoethers such as mono-2-ethylhexyl ether of ethylene glycol or propylene glycol, oximes such as dimethylketoxime, methylethylketoxime, methylisobutylketoxime, caprolactam or a mixture thereof, Aliphatic monoalcohol and glycol ether are preferably used. It is generally preferred to react the diisocyanate compound first with methanol or ethanol to block one isocyanate group and then the remaining isocyanate groups. In the electrodeposition coating composition, an aliphatic monoalcohol having 4 or more carbon atoms, an alkylphenol or a glycol monoether may be added separately as a heat flow improving agent for the coating film. A heat flow improver can be incorporated. Alternatively, the first isocyanate group may be a blocked isocyanate group that preferentially or selectively reacts with the epoxy ring by reaction with methanol or ethanol, and the second isocyanate group may be reacted with an active hydrogen compound that does not regenerate the isocyanate group. You may use. Examples of such active hydrogen compounds are primary amines such as methylamine, octylamine, polyoxyalkylene monoamines, and aliphatic monocarboxylic acids such as octanoic acid, 2-ethylhexanoic acid.

The ratio of the starting epoxy resin to the asymmetric blocked diisocyanate compound is not constant depending on the specific starting resin used, the diisocyanate compound, the amine equivalent of the modified epoxy resin as the final product, and the like. The ratio of groups must be less than 1. In other words, the epoxy ring must remain in the product of the first step. The reaction temperature is preferably 60 ° C to 200 ° C, and it is preferable to remove by-produced methanol or ethanol from the system by using a decanter or the like. Further, the above-mentioned chain extension may be carried out after the reaction with the asymmetric blocked diisocyanate.

Second Step The second step may be a conventional method in which the epoxy ring is opened with an active hydrogen compound such as an amine to introduce a cationic group. That is, by utilizing the epoxy group remaining in the product of the first step, the cationic group is introduced by the reaction with the cationic active hydrogen compound.

Therefore, as the active hydrogen compound, an acid salt of a primary amine, a secondary amine, a tertiary amine, or a sulfide / acid mixture is reacted. Examples thereof include butylamine, octylamine, diethylamine, dibutylamine, methylbutylamine, monoethanolamine, diethanolamine, N-methylethanolamine, triethylamine acid salt, N, N-dimethylethanolamine acid salt, diethyl disulfide / acid mixture and the like. Besides, there are secondary amines obtained by blocking amino primary amines. A plurality of amines may be used in combination. When reacting with a primary amine, since it is 2 equivalents, it acts as a chain extender for the polyepoxy compound and makes the polyepoxy compound high molecular weight. These amines that react with epoxy groups are
It is preferably used in approximately equivalent amounts to the epoxy groups of the product of the first step. 0.3 to 4.0 meq as amine equivalent
/ G is preferred. If the amine equivalent is less than 0.3 meq / g, it is difficult to emulsify and water-solubilize, and if it exceeds 4.0 meq / g, the water resistance of the coating film obtained after film formation becomes insufficient.

For use as a dispersant for pigment pastes, the cationic groups introduced by opening the epoxy ring must be in the form of quaternary ammonium or sulfonium salts. Therefore, the epoxy ring remaining in the resin after the first step is opened by reaction with a mixture or salt of a tertiary amine and a carboxylic acid or a mixture of a sulfide compound and a carboxylic acid.

The tertiary amine which can be used for this purpose is preferably an aliphatic tertiary amine substituted with a hydroxyl group, for example, dimethylethanolamine, diethylethanolamine and the like. Similarly, a sulfide compound is an aliphatic sulfide compound substituted with a hydroxyl group, for example, thiobisethanol, 1- (2-hydroxyethylthio) -2,
3-propanediol, 1- (2-hydroxyethylthio) -2-propanol, 1- (2-hydroxypropylthio) -2,3-propanediol, 1- (2-hydroxyethylthio) -2-butanol, 1- (2-hydroxyethylthio) -3-butoxy-1-propanol and the like are preferable.

As the carboxylic acid, formic acid, lactic acid, acetic acid, propionic acid, butyric acid, dimethylolpropionic acid,
Examples thereof include N-acetylglycine and N-acetyl-β-alanine, and lactic acid having a hydroxyl group or an amide group as a hydrophilic group in addition to the carboxyl group, dimethylolpropionic acid, N-acetyl-β-alanine and the like are preferable. .

For use as a resin for dispersing pigments,
It is preferable to have a base equivalent of 0.5 to 1.5 meq / g.

Electrodeposition Coating Composition The modified epoxy resin of the present invention can be self-crosslinked or crosslinked with an external crosslinking agent such as a melamine resin or a blocked polyisocyanate compound. The characteristics of the modified epoxy resin of the present invention are best exhibited by the electrodeposition paint. As described above, the modified epoxy resins for electrodeposition coatings up to now have not always been satisfactory in the reactivity with the crosslinking agent. The modified epoxy resin of the present invention is not only superior in curing reactivity to conventional resins, but also satisfies other properties required for resins for electrodeposition coatings, such as emulsifying property, heat flow property, corrosion resistance and heat resistance. .

The conversion to a paint can be achieved by dispersing the modified resin of the present invention and a crosslinking agent in an aqueous medium containing a neutralizing agent. Typical examples of the cross-linking agent are melamine resins such as etherified methylol melamine and blocked polyisocyanate compounds. As a matter of course, in the case of cationic electrodeposition paint, a modified resin having an amino group or a sulfonium group introduced is selected, and the neutralizing agent is hydrochloric acid, nitric acid,
It must be an inorganic or organic acid such as phosphoric acid, formic acid, acetic acid, lactic acid, sulfamic acid, acetylglycine.

The amount of cross-linking agent must be sufficient to react with functional groups such as hydroxyl groups in the resin during curing to give a good cured coating, generally 5 to 50% by weight of resin solids. used. The amount of the neutralizing agent is an amount sufficient to neutralize at least 20%, preferably 30 to 60% of amino groups and the like of the resin.

The coating may contain a tin compound such as dibutyltin dilaurate or tin acetate in a system containing a blocked polyisocyanate, and a usual urethane cleavage catalyst. The amount is usually 0.1 to 5% by weight of the blocked polyisocyanate compound.

The coating material includes coloring pigments such as titanium dioxide, carbon black and red iron oxide, rust preventive pigments such as basic lead silicate and aluminum phosphomolybdate, extender pigments such as kaolin, clay and talc, as well as water-miscible organic substances. It may contain conventional paint additives such as solvents, surfactants, antioxidants and UV absorbers.

The coating is particularly suitable for electrodeposition coating, but other coating methods such as dip coating and spray coating can also be used.

Pigment Dispersion Paste The modified epoxy resin of the present invention having a quaternary ammonium group or sulfonium base introduced as a cationic group is superior as a vehicle for a pigment dispersion paste for electrodeposition coatings to a known vehicle resin. This is because the blocked diisocyanate component is bonded to the epoxy resin by forming a chemically stable oxazolidone ring, so that the diisocyanate component does not desorb and volatilize during heat curing of the coating material.

The pigment-dispersed paste is obtained by well-dispersing a vehicle resin, a pigment, and deionized water in a particle size of 10 μm or less using a mill by a conventional method. As the pigment, the above-mentioned coloring pigment, extender pigment and rust preventive pigment may be appropriately mixed and used. The compounding ratio of the vehicle resin (solid content) and the pigment is generally in the range of 1: 1 to 1:10.

The pigment-dispersed paste thus obtained is not only a cationic electrodeposition paint using the modified resin of the present invention as a main resin for forming a coating film, but also an acrylic-based paste.
It can also be used in a cationic electrodeposition coating using another resin including an epoxy type or a polybutadiene type. Among them, in combination with a cationic electrodeposition coating composition containing a modified epoxy resin containing an oxazolidone ring in the chain and having an ionic group introduced at the terminal, which is disclosed in JP-A-5-306327 of the present inventors, as a main coating film component. Preference is given to using. This is because the chemical structures are similar to each other, so that they are well compatible with each other in the paint bath and the fluid coating film during baking, and phase separation does not occur.

Examples and comparative examples of the present invention will be shown below. "Parts" and "%" are based on weight unless otherwise specified. “Epoxy equivalent” and “amine equivalent” in the examples and comparative examples indicate numerical values per solid content.

Example 1 54.0 g of 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) and 136 g of methyl isobutyl ketone were placed in a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel. Further, 0.05 g of dibutyl tin laurate was weighed, nitrogen was bubbled while stirring, and 10.9 g of methanol was added dropwise from the dropping funnel over 30 minutes. The temperature started from room temperature and was raised to 60 ° C. Then, after continuing the reaction for 30 minutes, 54 g of ethylene glycol mono-2-ethylhexyl ether was added dropwise from the dropping funnel over 1 hour. The reaction was carried out mainly while maintaining the temperature in the range of 60 ° C to 65 ° C. The reaction continued until the isocyanate groups disappeared by infrared spectroscopy.

Thereafter, 285.0 g of a bisphenol A type epoxy resin having an epoxy equivalent of 475 synthesized from bisphenol A and epichlorohydrin and an epoxy equivalent of 950
Bisphenol A type epoxy resin of 380.0 g was added to a reaction vessel, uniformly mixed, heated to 120 ° C., benzyldimethylamine 0.62 g was added, and by-product methanol was distilled off using a decanter, The reaction was carried out until the epoxy equivalent became 1120. It is then cooled and then 29.1 g of diethanolamine, 21.5 N-methylethanolamine and a ketiminate of aminoethanolamine (79 wt% methyl isobutyl ketone solution).
32.9 g was added. The reaction was performed at 110 ° C. for 2.0 hours. In the IR spectrum, absorption at 1750 cm ^-1 based on the carbonyl group of the oxazolidone ring was observed. Then, with methyl isobutyl ketone, the nonvolatile content is 80%.
Diluted to. Thus, a cationic electrodeposition resin A having a blocked isocyanate group and an oxazolidone bond at its end was obtained. Number average molecular weight 2600, amine equivalent 99m
eq / 100g

Example 2 Following the same reaction procedure as in Example 1, 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) 57.4.
First, 11.6 g of methanol was reacted with g, and then 60.8 g of dipropylene glycol monobutyl ether was reacted therewith to obtain an asymmetric blocked diisocyanate compound.

Next, 309 g of a bisphenol F type epoxy resin having an epoxy equivalent of 475 and 332 g of a bisphenol F type epoxy resin having an epoxy equivalent of 950 are added and reacted, and further, 27.0 g of diethanolamine, 20.0 g of N-methylethanolamine and aminoethyl. 32.9 g of ketiminized product of ethanolamine (79 wt% methyl isobutyl ketone solution) was added and reacted, and then diluted with methyl isobutyl ketone to a nonvolatile content of 80%. Thus, a cationic electrodeposition resin B having a blocked isocyanate group and an oxazolidone bond at its end was obtained. Number average molecular weight 2400, amine equivalent 97 meq / 1
00g

Example 3 Flask equipped with stirrer, condenser, nitrogen injection tube, thermometer and dropping funnel 74,5 g of 4,4'-diphenylmethane diisocyanate and methylisobutyl paste 13
6 g and 0.05 g of dibutyl tin laurate are weighed, stirred, and bubbled with nitrogen, while stirring with methanol 1
0.9 g was added dropwise from the dropping funnel over 30 minutes. The temperature started from room temperature and was raised to 80 ° C. Then 30
After continuing the reaction for 1 minute, 52.2 g of ethylene glycol mono-2-ethylhexyl ether was added dropwise from the dropping funnel over 1 hour. The reaction was carried out mainly while maintaining the range of 80 ° C to 85 ° C. The reaction continued until the isocyanate groups disappeared by infrared spectroscopy.

Thereafter, 309.0 g of a bisphenol F type epoxy resin having an epoxy equivalent of 475 synthesized from bisphenol F and epichlorohydrin and an epoxy equivalent of 950.
332.0 g of bisphenol F type epoxy resin of No. 1 was added to a reaction vessel and uniformly mixed, the temperature was raised to 120 ° C., 0.62 g of benzyl dimethylamine was added, and methanol produced as a by-product was distilled off using a decanter while the epoxy was added. The reaction was continued until the equivalent weight reached 1116. Then, the mixture was cooled, 14.6 g of diethanolamine, 31.8 g of N-methylethanolamine, and 32.9 g of a ketimine compound of aminoethylethanolamine (79 wt% methyl isobutyl ketone solution) were added and reacted at 110 ° C. for 2.0 hours. It was In the IR spectrum, absorption at 1750 cm ^-1 based on the carbonyl group of the oxazolidone ring was observed. afterwards,
Diluted to 80% non-volatile with methyl isobutyl ketone. Thus, a cationic electrodeposition resin C having a blocked isocyanate group and an oxazolidone bond at the terminal was obtained. Number average molecular weight 2700, amine equivalent 98 meq / 1
00g

Example 4 According to the same reaction procedure as in Example 1, 82.5 g of 4,4'-diphenylmethane diisocyanate was first reacted with 10.5 g of methanol, and then 34.8 g of ethylene glycol mono-2-ethylhexyl ether and ε-. A mixture of 11.3 g of caprolactam was reacted and blocked.

Next, 285 g of bisphenol F type epoxy resin having an epoxy equivalent of 475 and 380 g of bisphenol F type epoxy resin having an epoxy equivalent of 950 are added and reacted.
Further, 13.9 g of diethanolamine, 28.9 g of N-methylethanolamine, and 22.0 g of a ketiminized product of aminoethylethanolamine (79 wt% methyl isobutyl ketone solution) were added and reacted, and the nonvolatile content was diluted to 80% with methyl isobutyl ketone. The number average molecular weight of the obtained cationic electrodeposition resin D was 2,600. Amine equivalent 95 meq / 100 g

Example 5 Following the same reaction procedure as in Example 1, 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) 57.0
First, 10.5 g of methanol was reacted with g of ethylene glycol mono-2-ethylhexyl ether.
0 g was reacted and blocked. Next, epoxy equivalent 12
Of 100 modified epoxy resin (1012.0 g of bisphenol A type epoxy resin having an epoxy equivalent of 650 (reaction product with bisphenol A / ethylene oxide adduct (BPE-100 manufactured by Sanyo Chemical Industries Co., Ltd.) 186.0 g)) and reacted. , And further diethanolamine 29.1
g, N-methylethanolamine 21.5 g and aminoethylethanolamine ketimine compound (79 wt%
Methyl isobutyl ketone solution) 32.9 g,
Diluted to a non-volatile content of 80% with methyl isobutyl ketone.
The number average molecular weight of the obtained cationic electrodeposition resin E is 2800.
Met. Amine equivalent 98 meq / 100 g

Comparative Example 1 285.0 g of an epoxy resin having an epoxy equivalent of 475 synthesized from bisphenol A and epichlorohydrin, 285.0 g, an epoxy resin having an epoxy equivalent of 950, 380.0 g, P-nonylphenol, 77.0 g and methyl were placed in the same reaction vessel as in Example 1. 82.4 g of isobutyl ketone was weighed out, heated, and uniformly mixed, and then 3.0 g of N, N-dimethylbenzylamine was added, and the mixture was reacted at a reaction temperature of 150 ° C. and reacted until the epoxy equivalent was 1140. . After cooling, 19.2 g of diethanolamine, 27.0 g of N-methylethanolamine, and 30.6 g of a ketimine compound of aminoethylethanolamine (79 wt% methyl isobutyl ketone solution) were added, and the reaction was conducted at 110 ° C. for 2.0 hours. It was made to react. Thereafter, the resin was diluted with methyl isobutyl ketone until the nonvolatile content became 90% to obtain a comparative resin a. Number average molecular weight 2100, amine equivalent 90 meq /
100g

Comparative Example 2 Following the same reaction procedure as in Comparative Example 1, p was added in the first step.
-Using 12-hydroxystearic acid 99.0 instead of nonylphenol 77.0g, in the second step diethanolamine 27.9g, N-methylethanolamine 19.8g, aminoethylethanolamine ketimine solution 31.5g. Comparative Example 1 except that it was changed
The above procedure was repeated to obtain a comparative resin b having a number average molecular weight of 2700. Amine equivalent 90 meq / 100 g

Comparative Example 3 In a reaction vessel similar to that of Example 1, 26.1 g of 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) and 13.0 g of methyl isobutyl ketone were weighed and stirred, and nitrogen was added. While bubbling, 26.1 g of ethylene glycol mono-2-ethylhexyl ether was added dropwise from the dropping funnel over 1 hour. The reaction started from room temperature and was heated to 60 ° C., and reacted for 1 hour. NCO equivalent at that time is 350
Met. The above half-blocked isocyanate solution was dissolved from bisphenol A and epichlorohydrin in an amount of 95.0 g of an epoxy resin having an epoxy equivalent of 475 and 760.0 g of an epoxy resin having an epoxy equivalent of 950 dissolved in 150.0 g of methyl isobutyl ketone. Then, the mixture was allowed to react by an infrared spectrometer until the absorption based on the NCO group disappeared. Thereafter, the mixture was cooled to 110 ° C., 35.4 g of diethanolamine, 25.2 g of N-methylethanolamine, and 40.0 g of a ketimine compound of aminoethylethanolamine (79 wt% methyl isobutyl ketone solution) were added, and the reaction was performed for 2.0 hours. It was
Then, it was diluted with methyl isobutyl ketone until the nonvolatile content became 85.0% to obtain a comparative resin c. Number average molecular weight 28
00, amine equivalent 100 meq / 100 g

Production Example of Pigment Dispersion Paste In a three-necked flask equipped with a reflux condenser, a thermometer, and a stirrer, a bisphenol A type epoxy resin having an epoxy equivalent of 190 (Epicote 828 Yuka Shell Epoxy Co., Ltd.)
740 g and bisphenol A211 g, methyl isobutyl ketone 48 g and benzyldimethylamine 1.5
The reaction was carried out at 170 ° C. for 2 hours in the presence of g to obtain a product having an epoxy equivalent of 700. To this, 244 g of thiodiethanol and 268 g of dimethylolpropionic acid were added, 50 g of ion-exchanged water was further added, and the mixture was reacted at 60 ° C. for 5 hours. The obtained resin was diluted with ethylene glycol monobutyl ether so that the solid content was 30%.

The pigment-dispersed paste was prepared by dispersing carbon black, kaolin titanium dioxide and basic lead silicate in the pigment-dispersed resin obtained above and pulverizing with a sand mill.

Compounding pigment dispersion resin 200.0 g (solid content 60 g) carbon black 4.0 g kaolin 36.0 g titanium oxide 150.0 g basic lead silicate 10.0 g ion-exchanged water 33.3 g

Synthesis Example of Crosslinking Agent Crosslinking Agent- I: 125.0 g of 4,4′-diphenylmethane diisocyanate and 75.0 g of methyl isobutyl ketone were placed in a flask equipped with a stirrer, a cooler, a nitrogen injection tube, a thermometer and a dropping funnel. Dibutyltin dilaurate 0.05g
While stirring, stirring and bubbling nitrogen, a mixture of 45.2 g of ε-caprolactam, 47.2 g of ethylene glycol monobutyl ether, 4.0 g of methanol, and 4.4 g of trimethylolpropane was added from the dropping funnel over 1 hour. Dropped. The temperature starts from room temperature and is 60 ℃
The temperature was raised to. After that, the reaction was continued for 1 hour, and the reaction was continued until the absorption of the NCO group disappeared by an infrared spectrometer.

Crosslinking agent- II: Hexamethylene diisocyanate trimer (Coronate HX: Nippon Polyurethane Co., Ltd.) in a flask equipped with a stirrer, a cooler, a nitrogen injection tube, a thermometer and a dropping funnel.
199 g), methyl isobutyl ketone 32 g, and dibutyl tin dilaurate 0.05 g were weighed, stirred and bubbled with nitrogen, and methyl ethyl ketoxime 87.0 g was added dropwise from the dropping funnel over 1 hour. The temperature started from 50 ° C and was raised to 70 ° C. Then, the reaction was continued for 1 hour, and the reaction was continued until the absorption of NCO group disappeared by an infrared spectrometer.

Example 6 Crosslinking agent-I (148 g (solid content)) and cationic electrodeposition resin A
252.0 g (solid content), dibutyltin oxide 5.0
g to a uniform mixture, heated to 80 ° C., and deionized water 26
It mixed with the acidic aqueous solution which melt | dissolved 6.24 g of acetic acid in 6.6 g, stirring with a disbar. Then, 445 g of deionized water was gradually added to obtain an emulsion solution having a solid content of 36 wt%. Next, concentration under reduced pressure was performed to remove the solvent, and deionized water was added to adjust the solid content to 36 wt%.

The particle size of this emulsion solution was measured by a spectrophotometer and is shown in Table 1.

Next, 270 g of the pigment dispersion paste (nonvolatile content 60%) obtained in the Production Example was mixed with this emulsion for coloring. Further, 1400 g of deionized water and 30 g of ethylene glycol monohexyl ether were added,
An electrodeposition paint having a nonvolatile content of 20% was obtained. Then, a zinc phosphate-treated steel plate was immersed as a cathode as an object to be coated, and coating was performed so that the dry film thickness was 20 μm. For the baking conditions, see the table.
The coating composition was evaluated under the conditions shown in FIG. The results are shown in Table-1.

Examples 7 to 10 and Comparative Examples 3 to 6 As shown in Tables 1 and 2, cross-linking agents-I and II,
The cationic electrodeposition resins B to E and the comparative resins a to c were made into paint by the same method as in Example 6 at a solid content ratio of 63/37 (resin / crosslinking agent), and the same evaluation was performed. The results of Examples 6 to 10 are shown in Table-1, and the results of Comparative Examples 3 to 6 are shown in Table-2.

[0063]

[Table 1]

[0064]

[Table 2]

Paint evaluation method 1) Ermersion particle size: spectrophotometer (U manufactured by Hitachi Ltd.)
-1100). 2) Curability: Evaluated by the appearance after acetone rubbing (30 times). ◯: No problem X: Luster shrink 3) Appearance (Ra): Measured with a surface roughness measuring device (E-30A manufactured by Tokyo Seimitsu Co., Ltd.). Unit = μm 4) Salt spray test: evaluated according to JIS-Z2371. ○: No action △: Detectable swelling ×: Severe swelling 5) Overcoat yellowing: Electrodeposition coating on a cylindrical metal container, baking in a sealed state, and then applying the metal container for automobile coating Paint (Nippon Paint Co., Ltd .: Alkyd resin /
Melamine resin white paint) was applied. The coated plate was covered and baked at 140 ° C. for 20 minutes to evaluate the degree of coloring. ○: No change △: Slightly yellowed ×: Remarkably yellowed

Example 11 66.1 g of 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) and methyl isobutyl ketone 53 were placed in a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel. 0.3 g and dibutyltin laurate 0.12 g were weighed, nitrogen was bubbled while stirring, and 13.6 g of methanol was added dropwise from a dropping funnel over 30 minutes. The temperature started from room temperature and was raised to 60 ° C. Then, after continuing the reaction for 30 minutes, 46.8 g of 2-ethylhexyl alcohol was added dropwise from the dropping funnel over 1 hour. The reaction was carried out mainly while maintaining the temperature in the range of 60 ° C to 65 ° C. The reaction continued until the isocyanate groups disappeared by infrared spectroscopy.

Thereafter, 310.2 g of a bisphenol A type epoxy resin having an epoxy equivalent of 188 synthesized from bisphenol A and epichlorohydrin was added to the reaction vessel, mixed homogeneously, heated to 120 ° C., and 0.8 g of benzyldimethylamine was added. The temperature of the reaction product was raised to 125 ° C., and by-product methanol was distilled off using a decanter, and the reaction was performed so that the epoxy equivalent became 338. Based on carbonyl group of oxazolidone ring in IR spectrum 17
Absorption of 50 cm ^-1 was observed. Then, 57.0 g of bisphenol A was added and reacted at 120 ° C. to obtain a resin having an epoxy equivalent of 640. It is then cooled, then 92.3 g of thiodiethanol, 10 dimethylolpropionic acid.
0.5 g and ion-exchanged water 108.0 g were added, and 65
The reaction was carried out at 0 ° C until the acid value became 5 or less. Then, a non-volatile content of 60.0% was prepared with a mixed solvent of ethylene glycol monobutyl ether and dipropylene glycol monobutyl ether = 1/1, and a pigment dispersion resin F was obtained. The base equivalent of the obtained resin is 78 meq / 10.
It was 0 g.

Example 12 62.6 g of 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) and methyl isobutyl ketone 55 were placed in a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel. 1 g and dibutyltin laurate 0.12 g were weighed, nitrogen was bubbled while stirring, and 13.6 g of methanol was added dropwise from a dropping funnel over 30 minutes. The temperature started from room temperature and was raised to 60 ° C. Then, after continuing the reaction for 30 minutes, ethylene glycol mono-2-ethylhexyl alcohol 62.6
g was added dropwise from the dropping funnel over 1 hour. The reaction was carried out mainly while maintaining the temperature in the range of 60 ° C to 65 ° C. The reaction continued until the isocyanate groups disappeared by infrared spectroscopy.

Thereafter, 310.2 g of a bisphenol A type epoxy resin having an epoxy equivalent of 188 synthesized from bisphenol A and epichlorohydrin was added to a reaction vessel, uniformly mixed, heated to 120 ° C., and 0.8 g of benzyldimethylamine was added. The temperature of the reaction product was raised to 125 ° C., while the by-product methanol was distilled off using a decanter, the reaction was carried out to an epoxy equivalent of 350, then 57.0 g of bisphenol A was added and the reaction was carried out at 120 ° C. An equivalent weight of 660 resin was obtained. It is then cooled, then 102.2 g of 1- (2-hydroxyethylthio) -2-propanol, 10 of dimethylolpropionic acid.
0.5 g and ion-exchanged water 108.0 g were added, and 65
The reaction was carried out at 0 ° C until the acid value became 5 or less. Then, a non-volatile content of 60.0% was prepared with a mixed solvent of ethylene glycol monobutyl ether and dipropylene glycol monobutyl ether = 1/1, and the pigment dispersion resin G was prepared.
Got

Example 13 According to the same reaction vessel and reaction procedure as in Example 11, a reaction was carried out with the following formulation.

[0071]                 Component parts by weight ────────────────────────────────── 2,4-2,6-Tolylene diisocyanate 66.1 (TDI) Methanol 13.6 Diethylene glycol mono-2-ethyl 78.5 Hexyl ether Dibutyltin dilaurate 0.12 Methyl isobutyl ketone (MIBK) 56.9 Bisphenol A epoxy resin (epoxy equivalent 188) 310.2 Bisphenol A 57.0 Dimethylbenzylamine 0.8 1- (2-hydroxyethylthio) -2,3 114.0 -Propanediol Dimethylolpropionic acid 100.5 Deionized water 108.0 ───────────────────────────────────         726.3 in total

The reaction product was diluted to a non-volatile content of 60.0% with a mixed solution of ethylene glycol monobutyl ether / dipropylene glycol monobutyl ether 1: 1 to obtain a resin H for pigment dispersion. Base equivalent is 72.3 meq / 100
It was g.

Example 14 A reaction was carried out according to the following formulation according to the same reaction container and reaction procedure as in Example 11.

[0074]                 Component parts by weight ────────────────────────────────── TDI 66.1 Methanol 13.6 Ethylene glycol mono-2-ethylhexyl ether 62.6 Dibutyltin dilaurate 0.12 MIBK 55.1 Bisphenol A epoxy resin (epoxy equivalent 188) 310.2 Bisphenol A 57.0 Dimethylbenzylamine 0.8 1- (2-hydroxypropylthio) -2,3 124.5 -Propanediol Dimethylolpropionic acid 100.5 Deionized water 108.0 ───────────────────────────────────         720.0 in total

The reaction product was diluted with an ethylene glycol monobutyl ether / dipropylene glycol monobutyl ether 1: 1 mixed solution to a nonvolatile content of 60.0% to obtain a pigment dispersion resin I. Base equivalent is 72.9 meq / 100
It was g.

Example 15 A reaction was carried out according to the following formulation according to the same reaction vessel and reaction procedure as in Example 11.

[0077]                 Component parts by weight ────────────────────────────────── 4,4'-diphenylmethane diisocyanate 95.0 Methanol 13.6 Ethylene glycol mono-2-ethylhexyl ether 62.6 Dibutyltin dilaurate 0.12 MIBK 58.3 Bisphenol A epoxy resin (epoxy equivalent 188) 310.2 Bisphenol A 57.0 Thiodiethanol 92.3 Dimethylolpropionic acid 100.5 Deionized water 108.0 ───────────────────────────────────         717.6 in total

The reaction product was diluted with an ethylene glycol monobutyl ether / dipropylene glycol monobutyl ether 1: 1 mixed solvent to a nonvolatile content of 60.0% to obtain a pigment-dispersing resin J. Base equivalent is 72.0 meq / 100
It was g.

Example 16 A reaction was carried out according to the following formulation according to the same reaction vessel and reaction procedure as in Example 11.

[0080]                 Component parts by weight ────────────────────────────────── TDI 66.1 Methanol 13.6 Ethylene glycol mono-2-ethylhexyl ether 62.6 Dibutyltin dilaurate 0.12 MIBK 67.0 Bisphenol A epoxy resin (epoxy equivalent 475) 475.0 Dimethylbenzylamine 0.8 1- (2-hydroxyethylthio) -2-propanol 81.7 Dimethylolpropionic acid 80.4 Deionized water 113.0 ───────────────────────────────────         Total 765.8

The reaction product was diluted with an ethylene glycol monobutyl ether / dipropylene glycol monobutyl ether 1: 1 mixed solvent to a nonvolatile content of 60.0% to obtain a pigment dispersion resin K. Base equivalent is 55.0 meq / 100
It was g.

Example 17 A reaction was carried out according to the following formulation according to the same reaction vessel and reaction procedure as in Example 11.

[0083]                 Component parts by weight ────────────────────────────────── TDI 26.1 Methanol 5.44 Ethylene glycol mono-2-ethylhexyl ether 24.4 Dibutyltin dilaurate 0.12 Bisphenol A epoxy resin (epoxy equivalent 188) 310.2 Bisphenol A 57.0 Dimethylbenzylamine 0.8 1- (2-hydroxyethylthio) -2-propanol 121.8 Dimethylolpropionic acid 132.7 Deionized water 129.6 ───────────────────────────────────         672.0 in total

The reaction product was diluted with an ethylene glycol monobutyl ether / dipropylene glycol monobutyl ether 1: 1 mixed solvent to a nonvolatile content of 60.0% to obtain a pigment dispersion resin L. Base equivalent is 146.0 meq / 10
It was 0 g.

Example 18 62.6 g of 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) and 55 of methyl isobutyl ketone were placed in a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel. 1 g and dibutyltin laurate 0.12 g were weighed, nitrogen was bubbled while stirring, and 13.6 g of methanol was added dropwise from a dropping funnel over 30 minutes. The temperature was raised from room temperature to 60 ° C by fitting. Then, after continuing the reaction for 30 minutes, ethylene glycol mono-2-ethylhexyl alcohol 62.6
g was added dropwise from the dropping funnel over 1 hour. The reaction was carried out mainly while maintaining the temperature in the range of 60 ° C to 65 ° C. The reaction continued until the isocyanate groups disappeared by infrared spectroscopy.

Then, 475.0 g of a bisphenol A type epoxy resin having an epoxy equivalent of 475, which was synthesized from bisphenol A and epichlorohydrin, was added to the reaction vessel, uniformly mixed, heated to 120 ° C., and 0.8 g of benzyldimethylamine was added. The temperature of the reaction product was raised to 125 ° C., and by-product methanol was distilled off using a decanter, and reacted until the epoxy equivalent became 1010. It is then cooled and then dimethylethanolamine 62.3
g, lactic acid 63.0 g, and ion-exchanged water 108.0 g were added, and the mixture was reacted at 80 ° C. until the acid value became 1 or less.
Then, a non-volatile content of 60.0% was prepared with a mixed solvent of ethylene glycol monobutyl ether and dipropylene glycol monobutyl ether = 1/1 to obtain a pigment dispersion resin M.

Example 19 62.6 g of 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) and 55 of methyl isobutyl ketone were placed in a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel. 1 g and dibutyltin laurate 0.12 g were weighed, nitrogen was bubbled while stirring, and 13.6 g of methanol was added dropwise from a dropping funnel over 30 minutes. The temperature was raised from room temperature to 60 ° C by fitting. Then, after continuing the reaction for 30 minutes, ethylene glycol mono-2-ethylhexyl alcohol 62.6
g was added dropwise from the dropping funnel over 1 hour. The reaction was carried out mainly while maintaining the temperature in the range of 60 ° C to 65 ° C. The reaction continued until the isocyanate groups disappeared by infrared spectroscopy.

Thereafter, 475.0 g of a bisphenol A type epoxy resin having an epoxy equivalent of 475, which was synthesized from bisphenol A and epichlorohydrin, was added to the reaction vessel, uniformly mixed, heated to 120 ° C., and 0.8 g of benzyldimethylamine was added. The temperature of the reaction product was raised to 125 ° C., and by-product methanol was distilled off using a decanter, and reacted until the epoxy equivalent became 1010. It is then cooled and then N-methylethanolamine 51.8.
g was added and reacted until the epoxy group disappeared. Then, 101.0 g of glycidol, 90 g of lactic acid and 108.0 g of ion-exchanged water were added, and the mixture was reacted at 80 ° C. until the acid value became 1 or less. Then, a non-volatile content of 60.0% was prepared with a mixed solvent of ethylene glycol monobutyl ether and dipropylene glycol monobutyl ether = 1/1 to obtain a pigment dispersion resin N.

Example 20 In the same manner as in Example 18, the reaction was carried out according to the reaction vessel and the reaction procedure and the following formulation.

[0090]                 Component parts by weight ────────────────────────────────── TDI 26.1 Methanol 5.44 Ethylene glycol mono-2-ethylhexyl ether 24.4 Dibutyltin dilaurate 0.12 MIBK 190.5 Bisphenol A epoxy resin (epoxy equivalent 950) 950.0 Dimethylbenzylamine 0.8 Dimethyl ethanolamine 62.3     Lactic acid (50%) 63.0 ───────────────────────────────────         1204.0 in total

The reaction product was diluted to a nonvolatile content of 60.0% with a mixed solvent of ethylene glycol monobutyl ether / dipropylene glycol monobutyl ether 1: 1 to obtain a pigment dispersion resin O. Base equivalent is 48.0 meq / 100
It was g.

Comparative Example 7           Component Weight part Solid content ─────────────────────────────────── Epon 828 533.2 533.2 Bisphenol A 199.6 199.6 Nonylphenol 19.2 19.2 Ethyltriphenylphosphonium iodide 0.75 ──── Propylene glycol monobutyl ether 201.6 ──── Thiodiethanol 122.1 122.1 Dimethylolpropionic acid 134.1 134.1 Deionized water 30.6 ──── ───────────────────────────────────

Epon 828, bisphenol A and nonylphenol were placed in a reaction vessel, heated to 107 ° C. and kept at this temperature until the bisphenol A was dissolved. Ethyltriphenylphosphonium iodide was then added and the mixture heated to 125 ° C. The reaction mixture was then cooled to 75 ° C. and propylene glycol monobutyl ether, thiodiethanol, dimethylolpropionic acid and deionized water were added. Then, the reaction product was heated to 70 to 75 ° C. until the acid value became 3 or less, to obtain a cationic resin for pigment dispersion. The reaction is cooled and 30
The pigment dispersion varnish P was prepared by diluting with water until the amount of the individuality was 100%.

Comparative Example 8 1) Preparation of quaternizing agent           Component Weight part Solid content ─────────────────────────────────── 2-ethylhexanol half blocked 320.0 304.0 TDI (diluted with MIBK) Dimethylethanolamine 87.2 87.2 75% lactic acid aqueous solution 117.6 88.2 Ethylene glycol monobutyl ether 39.2 ──── ───────────────────────────────────

Then, according to the above composition, using a suitable container, at room temperature, 2-ethylhexanol half-blocked T
DI was added to dimethylethanolamine. The mixture exothermed and was stirred at 80 ° C. for 1 hour. Then, lactic acid was charged, and ethylene glycol monobutyl ether was further added. The reaction mixture was stirred at 65 ° C. for about half an hour to give the quaternizing agent.

[0096] 2) Preparation of resin vehicle           Component Weight part Solid content ─────────────────────────────────── Epon 829 710.0 681.2 Bisphenol A 289.6 289.6 2-ethylhexanol half-blocked 406.4 386.1 TDI (diluted with MIBK) 1) Quaternizing agent 496.3 421.9 Deionized water 71.2 ──── Ethylene glycol monobutyl ether 56.76 ──── ───────────────────────────────────

According to the above composition, Epon 829 and bisphenol A were charged into a suitable reaction vessel, reacted at 150 to 160 ° C. for about 1 hour under a nitrogen atmosphere, and then 120
After cooling to ° C, 2-ethylhexanol half blocked TDI was added. Then, the mixture was cooled to 85 to 95 ° C., homogenized, and the quaternizing agent of 1) was added. The reaction mixture was kept at 80 to 85 ° C. until the acid value became 1 or less to obtain a varnish Q for dispersing pigment.

Examples 21 to 30 and Comparative Examples 9 to 10 Preparation of Pigment Dispersion Paste Pigment dispersion resins F to Q and pigments were mixed in the following composition,
The pigment was dispersed in a sand grind mill and pulverized to a particle size of 10 μm or less to prepare a pigment dispersion paste. The dispersion paste was evaluated. The results are shown in Table 3.

[0099]     Component parts by weight ───────────── ──────── Pigment dispersion resin varnish 125.0 (resin solid content 60.0%) Ion-exchanged water 400.0 Carbon black 8.5 Kaolin 72.0 Titanium oxide 345.0 Aluminum phosphomolybdate 75.0

Synthesis of base resin In a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel, a bisphenol A epoxy resin and an oxazolidone-containing epoxy resin synthesized from tolylene diisocyanate (epoxy equivalent: 475, oxazolidone ring equivalent) : 650) 285.0 g, an epoxy resin having an epoxy equivalent of 950, 380.0 g, P-nonylphenol, 77.0 g, and methyl isobutyl ketone, 82.
4 g of each was weighed, heated to a uniform temperature, and mixed uniformly with 3.0 g of benzyldimethylamine.
The reaction was carried out at 0 ° C. until the epoxy equivalent became 1140. It is then cooled and diethanolamine 19.2.
g, N-methylethanolamine 27.0 g and aminoethylethanolamine ketimine compound (79 wt%
30.6 g of a methyl isobutyl ketone solution) was added, and the reaction was carried out at 110 ° C. for 2 hours. After that, the base resin was obtained by diluting with methyl isobutyl ketone until the nonvolatile content became 90%.

Synthesis of Crosslinking Agent A hexamethylene diisocyanate trimer (Coronate HX: Nippon Polyurethane Co., Ltd.) was placed in a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel.
199 g), methyl isobutyl ketone 32 g, and butyltin dilaurate 0.05 g are weighed and stirred,
While vibrating nitrogen, 87.0 g of methyl ethyl ketoxime was added dropwise from the dropping funnel over 1 hour.
The temperature started from 50 ° C and was raised to 70 ° C. After that, the reaction was continued, and the reaction was continued until the absorption of the NCO group disappeared by an infrared spectrometer.

Preparation of Main Emulsion The above-synthesized base resin / crosslinking agent = 68/32 (solid content ratio) was blended, and ethylene glycol / monohexyl alcohol was added so as to be 2% based on the solid content. After neutralizing with glacial acetic acid to a neutralization ratio of 42.5%, the mixture was slowly diluted with deionized water.

Methyl isobutyl ketone was removed from this under reduced pressure so that the solid content was 36.0%.

Preparation and Evaluation of Coating Solution 2000.0 g of main emulsion, 460.0 g of pigment dispersion paste and 2252.0 g of ion-exchanged water were added to each to prepare a cationic electrodeposition coating having a solid content of 20.0%.

Then, the prepared coating material was electrodeposited on a zinc phosphate-treated cold-rolled steel sheet to give a dry film thickness of 20 μm, and baked at 160 ° C. for 10 minutes. After that, various coating film evaluations were performed. The obtained results are shown in Table 3.

[0106]

[Table 3]

Pigment Dispersion Paste and Paint Evaluation Method 1) Thermal Decomposition The thermal decomposition of the resin under high temperature conditions was evaluated. (22
0 ° C. × 20 min) ◯: No diisocyanate component volatilized ×: Diisocyanate component volatilized 2) Pigment dispersion paste state The sedimentation state of the paste after standing at 40 ° C. for 2 weeks was visually evaluated. ◯: Good Δ: Slight sedimentation ×: Cake-like sedimentation or phase separation 3) Cloning efficiency Coating efficiency (mg / C) when electrodeposition coating was carried out under the coating conditions to obtain a film thickness of 20 μ ○: 35 mg <×: 35 mg> 4 ) Salt Spray Test Evaluation was performed according to JIS-Z2371. ◯: No action Δ: Detectable blisters x: Overall 5) Topcoat yellowing electrodeposition coating (160 ° C x 10 min and 180 ° C x 20)
min) and spray a white-based intermediate coating,
The color difference when baked at 20 ° C. for 20 minutes was visually evaluated. ◯: No discoloration Δ: Slightly discolored ×: Significant discoloration (standard is an intermediate coating film directly applied on a metal plate)

Example 31 54.0 g of 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) and 136 g of methyl isobutyl ketone were placed in a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel. Further, 0.05 g of dibutyl tin laurate was weighed, nitrogen was bubbled while stirring, and 10.9 g of methanol was added dropwise from the dropping funnel over 30 minutes. The temperature started from room temperature and was raised to 60 ° C. Then, after continuing the reaction for 30 minutes, 36.2 g of dibutylamine was added dropwise from the dropping funnel over 1 hour.
The reaction was carried out mainly while maintaining the temperature in the range of 60 ° C to 65 ° C. The reaction continued until the isocyanate groups disappeared by infrared spectroscopy.

Then, 285.0 g of a bisphenol A type epoxy resin having an epoxy equivalent of 475 synthesized from bisphenol A and epichlorohydrin and an epoxy equivalent of 950
Of bisphenol A type epoxy resin (380.0 g) was added to the reaction vessel, uniformly mixed, heated to 120 ° C., added with benzyldimethylamine (0.62 g), and added with a reaction product of 135
The temperature was raised to 0 ° C., and by-product methanol was distilled off using a decanter, and reacted until the epoxy equivalent became 1120. Then cool down and then diethanolamine 2
9.1 g, N-methylethanolamine 21.5, and aminoethylethanolamine ketimine compound (79
32.9 g of a wt% methyl isobutyl ketone solution) was added. The reaction was performed at 110 ° C. for 2.0 hours. I
In the R spectrum, absorption at 1750 cm ^-1 based on the carbonyl group of the oxazolidone ring was observed. Then, it was diluted with methyl isobutyl ketone to a nonvolatile content of 80%. Thus, a cationic electrodeposition resin R having a half-blocked isocyanate group and an oxazolidone bond at the terminal was obtained. An emulsion was prepared in the same manner as in Example 6 to obtain a good emulsion.

Example 32 54.0 g of 2,4 / 2,6-tolylene diisocyanate (80/20 wt ratio) and 136 g of methyl isobutyl ketone were placed in a flask equipped with a stirrer, a condenser, a nitrogen injection tube, a thermometer and a dropping funnel. Further, 0.05 g of dibutyl tin laurate was weighed, nitrogen was bubbled while stirring, and 10.9 g of methanol was added dropwise from the dropping funnel over 30 minutes. The temperature started from room temperature and was raised to 60 ° C. Then, after continuing the reaction for 30 minutes, octylic acid 4
0.4 g was added. The reaction was mainly carried out while maintaining the range of 60 ° C to 85 ° C. The reaction continued until the isocyanate groups disappeared by infrared spectroscopy.

Then, 285.0 g of a bisphenol A type epoxy resin having an epoxy equivalent of 475 synthesized from bisphenol A and epichlorohydrin and an epoxy equivalent of 950
Of bisphenol A type epoxy resin (380.0 g) was added to the reaction vessel, uniformly mixed, heated to 120 ° C., added with benzyldimethylamine (0.62 g), and added with a reaction product of 135
The temperature was raised to 0 ° C., and by-product methanol was distilled off using a decanter, and reacted until the epoxy equivalent became 1120. Then cool down and then diethanolamine 2
9.1 g, N-methylethanolamine 21.5, and aminoethylethanolamine ketimine compound (79
32.9 g of a wt% methyl isobutyl ketone solution) was added. The reaction was performed at 110 ° C. for 2.0 hours. I
In the R spectrum, absorption at 1750 cm ^-1 based on the carbonyl group of the oxazolidone ring was observed. Then, it was diluted with methyl isobutyl ketone to a nonvolatile content of 80%. Thus, a cationic electrodeposition resin S having a half-blocked isocyanate group and an oxazolidone bond at the terminal was obtained. An emulsion was prepared in the same manner as in Example 6 to obtain a good emulsion.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C09D 175/04 C09D 175/04 (72) Inventor Ichiro Kawakami 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd. (56 ) Reference JP-A-4-226172 (JP, A) JP-A-49-99337 (JP, A) JP-A-2-73822 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) C08G 18/00-18/87 C08G 59/14-59/17 CA (STN) REGISTRY (STN)

Claims (15)

(57) [Claims] 1. An isocyanate component bonded to a resin skeleton by an oxazolidone ring formed by a reaction of a part of epoxy rings of an epoxy resin having a plurality of glycidyloxy groups and one isocyanate group of a diisocyanate compound, and the rest. Of the epoxy ring having a cationic group formed by ring-opening with a cationic active hydrogen compound, and the other isocyanate group of the bonded isocyanate component is bonded to a blocking agent or an active hydrogen compound that does not regenerate the isocyanate group. Modified epoxy resin characterized by. 2. The modified epoxy resin according to claim 1, wherein the epoxy resin is a diglycidyl ether type or diglycidyl ester type epoxy resin, or a chain extension resin thereof. 3. The other isocyanate group of the bonded isocyanate component is an aliphatic monoalcohol having 4 or more carbon atoms, alkylphenol, glycol monoether,
The modified epoxy resin according to claim 1 or 2, which is blocked with a ketoxime, caprolactam, a tertiary aminoalkanol, or a secondary amine. 4. The modified epoxy resin according to claim 1, wherein the other isocyanate group of the bonded isocyanate component is converted into a group that does not regenerate the isocyanate group by reaction with a primary amine or an aliphatic monocarboxylic acid. . 5. The cationic active hydrogen compound which opens the remaining epoxy ring is a primary amine, a secondary amine, a tertiary amine acid addition salt, or a sulfide-acid mixture. Modified epoxy resin. 6. An epoxy resin having a plurality of glycidyloxy groups as a starting material, a part of the epoxy ring of the epoxy resin, a first blocked isocyanate group and a second blocked isocyanate group having a higher reactivity than the first blocked isocyanate group. of having a blocked isocyanate group, or the first to play isocyanate groups
No regeneration of active hydrogen compounds and isocyanate groups
The asymmetric blocked diisocyanate compound having an isocyanate group respectively bonded to the active hydrogen compound of 2 is reacted to give a second blocked isocyanate group or an isocyanate group.
Bound to the first active hydrogen compound that regenerates the anate group
Formed by the reaction of an isocyanate group with an epoxy ring
Modification comprising the steps of obtaining a reaction product having a oxazolidone ring formed therein and introducing a cationic group by a ring-opening reaction between the epoxy ring remaining in the reaction product and a cationic active hydrogen compound. Method for producing epoxy resin. 7. The method according to claim 6, wherein the epoxy resin is a diglycidyl ether type or diglycidyl ester type epoxy resin, or a resin obtained by chain extension thereof. 8. The first blocked isocyanate group of the asymmetric blocked diisocyanate compound is an aliphatic monoalcohol having 4 or more carbon atoms, alkylphenol, glycol monoether, ketoxime, caprolactam, 3
7. A secondary aminoalkanol or secondary amine is blocked, and the second blocked isocyanate group is blocked with methanol or ethanol.
Or method 7 9. The asymmetric blocked diisocyanate compound is bonded to methanol or ethanol as an active hydrogen compound that regenerates an isocyanate group and to a primary amine or an aliphatic monocarboxylic acid as an active hydrogen compound that does not regenerate an isocyanate group. The method according to claim 6 or 7. 10. The method according to claim 6, wherein the cationic active hydrogen compound is a primary amine, a secondary amine, a tertiary amine acid addition salt, or a sulfide-acid mixture. 11. An aqueous coating composition obtained by dispersing the modified epoxy resin according to any one of claims 1 to 4 and a crosslinking agent in an aqueous medium containing a neutralizing agent. 12. The aqueous coating composition according to claim 11, wherein the crosslinking agent is a blocked polyisocyanate. 13. The cross-linking agent is a melamine resin.
Water-based coating composition. 14. The modified epoxy resin according to claim 1, wherein the cationic group is a quaternary ammonium salt or a sulfonium salt. 15. A pigment-dispersed paste for electrodeposition paint, which comprises dispersing a pigment in the modified epoxy resin solution according to claim 14.