JPH0621237B2 - Cathode deposition type electrodeposition coating composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cathodic deposition type electrodeposition coating composition having excellent low temperature curability.

(Problems to be Solved by Conventional Techniques and Inventions) A resin having a certain type of basic group produces a cationic resin in water, and when this is used for electrodeposition coating, the resin serves as a cathode. To deposit. This type of cathodic deposition type coating is a water-soluble neutralization of a resin having an acid group, which is an essential drawback of conventional anodic deposition type electrodeposition coatings. It is possible to eliminate the elution of water and various problems resulting therefrom.

The present inventors have studied such a cathodic deposition type coating,
Low-degree synthetic polymer having a carbon-carbon double bond, for example, cathodic deposition which gives an excellent coating property by introducing an amino group into an unsaturated group-containing high molecular weight compound such as liquid polybutadiene and neutralizing with an acid. The inventors have found that a resin for electro-deposition coating can be obtained, and applied for a patent (Japanese Patent Application Laid-Open No. 51-1197).
27, JP-A-52-147638, JP-A-53-160.
48).

Cathode deposition type electrodeposition coating composition containing the above resin as a coating component is mainly cured by oxidative polymerization of unsaturated groups contained in the resin to give a coating having excellent performance, but with a practical curing time. Relatively high baking temperatures are required for hardening. As a result of research into lowering the baking temperature, the present inventors have found that the coating film is cured at a relatively low baking temperature by adding a metal drier such as a water-soluble manganese salt, and applied for a patent (Japanese Patent Laid-Open No. 53-53113). -142444). In this case, a large amount of dryer is required, which causes problems such as deterioration of electrodeposition coating performance such as throwing power, and easy coating surface roughening. The present inventors also found a method of introducing a highly reactive acrylic (methacrylic) double bond into a resin and curing it at a relatively low baking temperature, and applied for a patent (Japanese Patent Laid-Open No. 56-151777). In this case, when a water-soluble manganese salt is added, it cures at a relatively low temperature of 160 ° C. and a cathodic deposition type electrodeposition coating having excellent performance can be obtained.

However, in recent years, it has been desired to further lower the baking temperature from the viewpoint of energy saving. As a result of various kinds of research conducted by the present inventors, it has a highly reactive acrylic (methacryl) double bond or a carbon-carbon conjugated double bond. Unsaturated monocarboxylic acids or their dimers and manganese in the resin,
The inventors have found that the baking temperature can be further lowered by adding a water-soluble salt of an organic acid of a metal selected from cobalt and copper, and have reached the present invention.

An object of the present invention is to provide a cathodic deposition type electrodeposition coating composition having improved curability of a resin and having low temperature curability and excellent corrosion resistance.

(Means for Solving the Problem) That is, the present invention provides (A) a carbon-carbon double bond having a molecular weight of 500 to 5,000 and an iodine value of 50 to 500 and an oxirane oxygen of 3;
General formula per 100 g of polymer compound having ~ 12 wt% [Wherein R ₁ and R ₂ represent a hydrocarbon having 1 to 20 carbon atoms, part of which may be substituted with a hydroxyl group, provided that R ₁ and R ₂ may have a ring structure, The unsaturated group may be contained therein. ] The amine compound represented by [In the formula, R ₃ and R ₄ represent a hydrogen atom or a methyl group. ] Α, β unsaturated carboxylic acid represented by or molecular weight 1
0-350 unsaturated fatty acid containing 10% by weight or more of carbon-carbon conjugated double bond or mixture thereof 0-200
100 parts by weight of millimoles of reaction product (B) General formula [In the formula, R ₅ and R ₆ are a hydrogen atom or a methyl group, and n is 0.
To 20 preferably represent an integer of 1 to 10] [In the formula, R ₃ and R ₄ represent a hydrogen atom or a methyl group. ] Α, β unsaturated carboxylic acid represented by or molecular weight 1
10-200 parts by weight of a saturated fatty acid having a carbon-carbon conjugated double bond in an amount of 0 to 350 and containing 10% by weight or more, or a mixture thereof 1.9 to 2.1 parts by weight (C) an unsaturated monocarboxylic acid having 6 to 24 carbon atoms 0.1 to 10 parts by weight of an acid or a duplication thereof (D) a low temperature curable composition containing 0.005 to 1.0 part by weight as a metal component of a water-soluble salt of an organic acid of a metal selected from mangagan, cobalt and copper It is an excellent cathodic deposition type electrodeposition coating composition.

The starting material of the component (A) of the present invention is 500 to 5,000.
The polymer compound having a carbon-carbon double bond having an iodine value of 50 to 500 with a molecular weight of is produced by a conventionally known method.

That is, by using an alkali metal or an organic alkali metal compound as a catalyst, a conjugated diolefin having 4 to 10 carbon atoms alone, or these diolephins, or an aromatic vinyl monomer in an amount of 50 mol% or less with respect to the conjugated diolefin, for example, styrene, α- A typical production method is a method of anionic polymerization or copolymerization with methylstyrene, vinyltoluene or divinylbenzene at a temperature of 0 ° C to 100 ° C. In this case, in order to control the molecular weight, to obtain a low-colored low polymer with less gel content, etc., an organic alkali metal compound such as benzyl sodium is used as a catalyst, and a compound having an alkylaryl group, for example, toluene is used as a chain transfer agent. Chain transfer polymerization method (US Pat. No. 37890)
90) or a living polymerization method in which a polycyclic aromatic compound such as naphthalene is used as an activator in a tetrahydrofuran solvent and an alkali metal such as sodium is used as a catalyst (Japanese Patent Publication Nos. 42-17485 and 43-27432), or Polymerization method in which aromatic hydrocarbons such as toluene and xylene are used as a solvent, a dispersion of an alkali metal such as sodium is used as a catalyst, and ethers such as dioxane are added to control the molecular weight (Japanese Patent Publication No. 32-7446). , 38-
Nos. 1245 and 34-10188) are suitable production methods. It is also produced by coordination anionic polymerization using an acetylacetonate compound of a Group 8 metal such as cobalt or nickel and an alkylaluminum halogenide as catalysts (Japanese Patent Publication Nos. 45-507 and 46-803).
No. 00) low polymers can also be used.

The component (A) of the present invention is obtained by epoxidizing the unsaturated compound by a known method using a peroxide such as hydrogen peroxide or peracid, and introducing 3 to 12% by weight of an oxirane oxygen group as oxygen.
General formula [Wherein R ₁ and R ₂ are the same as those defined above], after reacting the amine compound in the presence or absence of a solvent at a temperature of 50 to 200 ° C. [Wherein R ₃ and R ₄ are the same as above], and α or β unsaturated carboxylic acid or a molecular weight of 100
100 to 20 unsaturated fatty acids containing 10% by weight or more of carbon-carbon conjugated double bonds or a mixture thereof.
It is produced by reacting at 0 ° C.

Examples of amines used in the reaction include dimethylamine,
Examples thereof include aliphatic amines such as diethylamine, alkanolamines such as methylethanolamine and diethanolamine, and cyclic amines such as morpholine and piperidine.

The amount of amine added is 100 g of epoxidized polymer compound
30 to 300 mmol, preferably 50 to 200 mmol.

Examples of the α, β unsaturated carboxylic acid include acrylic acid, methacrylic acid and crotonic acid.

A carbon-carbon conjugated double bond having a molecular weight of 100 to 350
Unsaturated fatty acids containing by weight or more include sorbic acid, Sengoku tung oil fatty acid, sunflower oil fatty acid, dehydrated castor oil fatty acid, etc., and conjugated by isomerizing soybean oil fatty acid, linseed oil fatty acid, etc. A modified fatty acid can also be used, and purified eleostearic acid and conjugated linoleic acid can also be used. Further, a mixture in which an unsaturated fatty acid having 10% by weight or less of a carbon-carbon conjugated double bond is mixed with an unsaturated fatty acid having a large number of conjugated double bonds so that the total conjugated double bond is 10% by weight or more is also used. be able to. Among them, dehydrated castor oil fatty acid is advantageous and preferable because it is industrially easily available.

It is preferable to use such that the total amount of the α, β unsaturated carboxylic acid and the unsaturated fatty acid to be added is 50 to 150 mmol as the amount of carboxylic acid per 100 g of the epoxidized polymer compound.

Component (B) of the present invention, that is, the general formula [In the formula, R ₅ and R ₆ represent a hydrogen atom or a methyl group, n
Represents an integer of 0 to 20], and a diglycidyl compound represented by the general formula [In the formula, R ₃ and R ₄ represent a hydrogen atom or a methyl group. ] Α, β unsaturated carboxylic acid represented by or molecular weight 1
Addition of a compound prepared by reacting 1.9 to 2.1 mol of an unsaturated fatty acid having a carbon-carbon conjugated double bond content of at least 10% by weight at 0 to 350 or a mixture thereof significantly improves the corrosion resistance.

The content of the component (B) is 1 with respect to 100 parts by weight of the resin (A).
It is in the range of 0 to 200 parts by weight, preferably 30 to 100 parts by weight.

When the content of the component (B) is less than this, the corrosion resistance is not sufficiently improved, and when it is more than this, the water dispersibility is deteriorated.

To obtain the compound of component (B) above, a compound of the general formula [In the formula, R ₅ and R ₆ are the same as the above], and a diglycidyl compound is used as a raw material. The diglycidyl compound can be made by etherifying bisphenol with epichlorohydrin, usually in the presence of alkali. Examples of such bisphenol compounds include 2,2-bis (4'-hydroxyphenyl) propane, 1,1-bis (4'-hydroxyphenyl) ethane and 1,1-bis (4'-hydroxyphenyl). ) Isobutane, etc. In many cases, the above-mentioned diglycidyl ether is further reacted with bisphenol or the like, and then this product is further reacted with epichlorohydrin to synthesize a diglycidyl compound having a somewhat higher molecular weight, which can be used.

The above diglycidyl compound has a general formula at a temperature of 0 to 200 ° C., preferably 50 to 150 ° C. [Wherein, R ₃ and R ₄ represent a hydrogen atom or a methyl group] or an α, β unsaturated monocarboxylic acid having a molecular weight of 100 to 350 and containing 10% by weight of a carbon-carbon conjugated double bond.
The unsaturated fatty acid containing the above or a mixture thereof is substantially 2 mol (1.9 to 2.1 mol) per mol of the diglycidyl compound.
The component (B) can be produced by reacting (mol).

In carrying out the reaction, 0.01 to 1.0% of a radical polymerization inhibitor such as hydroquinone, metoquinone, N-phenyl.N'-isopropyl-P-phenylenediamine is added to prevent a side reaction, and a tertiary amine is added. It is preferred to use suitable catalysts such as salts and quaternary ammonium salts. The reaction can be carried out in the presence or absence of a solvent, but when a solvent is used, it is inert to the reaction, and a suitable solvent for the electrodeposition coating, such as ethyl cellosolve or MIBK, is used in an appropriate amount. It is practically advantageous to use it as an electrodeposition coating composition by mixing it with the components (A) and (C) without removing it after the reaction.

In the present invention, the epoxy group of the above diglycidyl compound React with the carboxylic acid group so that Is preferably converted to.

If a large amount remains, this group reacts unfavorably with the basic group of the resin (A) when it is solubilized by adding an acid later, causing gelation, resulting in too high a viscosity. Impairs water solubility. Even if water can be solubilized, the aqueous solution changes with time, which causes certain defects such as a certain electrodeposition characteristic or the inability to obtain an electrodeposition coating film.

Conventionally, a bisphenol type epoxy resin has been known as a resin excellent in corrosion resistance, and in order to impart crosslinkability to this, a part of the epoxy group may be left, or (Japanese Patent Publication No.
23807, Japanese Patent Publication No. 51-15860), attempts have been made to use a block isocyanate compound as a crosslinking agent. However, such a paint requires a high temperature such as 200 ° C. or higher to obtain practical hardness,
Even when it can be cured at a relatively low temperature, there is a drawback that only a narrow range of baking temperature can be selected.

Further, as the bisphenol type epoxy resin, a resin having a certain amount of high molecular weight substance must be used under practical electrodeposition conditions, and thus the coating film tends to lack flexibility.

Therefore, according to the present invention, the diglycidyl compound Practically all of The compound (B) converted into a can be used in combination with the resin (A) as one component of the cathodic deposition type electrodeposition coating composition, whereby the resin (A) has excellent curability and coating properties. It is truly surprising that it has been found that its corrosion resistance can be significantly improved without any loss.

Component (C) of the present invention, that is, an unsaturated monocarboxylic acid having 2 to 24 carbon atoms or a dimer thereof is added in an amount of 0.1 to 10
By adding 1 part by weight, preferably 1 to 5 parts by weight to the component (A), the component (B) and the component (D), curability is remarkably promoted, and a low temperature curable cathodic deposition type electrodeposition coating composition is obtained. can get.

If the addition amount of the component (C) is less than 0.1 parts by weight, the effect of promoting the curability is small, and if it is more than 10 parts by weight, the curability is good but the corrosion resistance is deteriorated, which is not preferable.

Examples of the component (C) of the present invention, tung oil fatty acid, linseed oil fatty acid, sunflower oil fatty acid, soybean oil fatty acid, dehydrated castor oil fatty acid, castor oil fatty acid, safflower oil fatty acid, tall oil fatty acid, oleic acid, linoleic acid, linolene Acid, eleostearic acid, beef fatty acid, so-called purified unsaturated fatty acid such as fish oil fatty acid, dehydrated castor oil fatty acid, conjugated unsaturated fatty acid obtained by isomerizing sunflower oil fatty acid, sorbic acid,
Unsaturated monocarboxylic acids such as cinnamic acid can be used.

Furthermore, cyclic unsaturated monocarboxylic acids such as abietic acid and pimaric acid obtained from natural rosin can also be used. The dimer includes dimer acid obtained from tall oil fatty acid and the like, and dimer rosin obtained from rosin. The above unsaturated monocarboxylic acids or their dimers can be used alone or in admixture.

Component (D) of the present invention, manganese, cobalt, the addition amount of a water-soluble salt of an organic acid of a metal selected from copper is 0.005 as a metal amount.
If it is less than 1 part by weight, the effect of promoting curability is small, and if it is more than 1.0 part by weight, curability is good, but water resistance,
It is not preferable because it lowers corrosion resistance. The preferable range is 0.01 to 0.5 part by weight as the amount of metal.

Examples of water-soluble metal salts of organic acids include manganese acetate, manganese lactate, cobalt acetate, copper acetate and the like.

In the present invention, component (A), component (B), component (C) and component
In order to make the composition comprising (D) water-soluble or water-dispersible, the components (A), (B) and (C) are mixed in advance, and then 0.1 to the amino group of the component (A) is added. 2.0 preferably
It is preferable to neutralize with a water-soluble organic acid such as formic acid, acetic acid, propionic acid, or lactic acid in an amount of 0.2 to 1.0 molar equivalent to solubilize it.

Since the component (D) is water-soluble, the component (A), the component (B) and the mixture of the component (C) are dissolved in water used for solubilizing in advance, or the component (A) or the component (B) is added. ) And ingredients
It can be added by a method such as adding it later to the aqueous dispersion of the mixture of (C).

In dissolving or dispersing the composition (A), (B) and (C) of the present invention in water, facilitates the dissolution or dispersion, improves the stability of the aqueous solution, improves the fluidity of the resin, the coating film For the purpose of improving the smoothness of, for example, water-soluble ethyl cellosolve, propyl cellosolve, butyl cellosolve, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, which can dissolve each resin composition,
It is preferable to use 10 to 100 parts by weight of an organic solvent such as diacetone alcohol, 4-methoxy-4-methylpentanone-2, and methyl ethyl ketone per 100 parts by weight of each resin composition.

A suitable pigment may be further added to the cathodic deposition type electrodeposition coating composition of the present invention. For example, one or more pigments such as iron oxide, lead oxide, strontium chromate, carbon black, titanium dioxide, talc, aluminum silicate and barium sulfate can be blended.

These pigments can be added as they are to the composition of the present invention.However, a large amount of pigment is added to a part of the component (A) which has been neutralized and dispersed or made into an aqueous solution in advance to form a paste-like master batch. The obtained pigment can be added to the composition.

(Examples) Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. The physical properties of the coating films of Examples and Comparative Examples were tested according to JIS-K-5400.

Production Example 1 Nisseki Polybutadiene B-2000 (number average molecular weight 200
0, 1.2 bond 65%) is epoxidized with peracetic acid,
Epoxidized polybutadiene (E ₁ ) with an oxirane oxygen content of 6.4% was prepared.

After 1,000 g of the epoxidized polybutadiene (E ₁ ) and 354 g of ethyl cellosolve were charged in 2 autoclaves, 62.1 g of dimethylamine was added, and the mixture was reacted at 150 ° C. for 5 hours. After distilling off unreacted amine, 120
After cooling to ℃, a mixture of 79.3 g of acrylic acid, 7.6 g of hydroquinone and 26.4 g of ethyl cellosolve was added, and the mixture was further reacted at 120 ° C. for 3 hours and 45 minutes to prepare a resin solution (A ₁ ) of the component (A) of the present invention. did. The amine value of this product is 8
5.2 mmol / 100g, acid value 10.0 mmol / 100
The solids concentration was 75.0% by weight.

Production Example 2 Nisseki Polybutadiene B-1,800 (number average molecular weight 18
00, 1.2 bond 64%) was epoxidized with peracetic acid to produce epoxidized polybutadiene (E ₂ ) having an oxirane oxygen content of 6.5%.

1,000 g of this epoxidized polybutadiene (E ₂ ), 377 g of ethyl cellosolve and 131.0 g of methyl ethanolamine were charged into a 3 separable flask, and 17
The reaction was carried out at 0 ° C for 6 hours. After the reaction, the mixture was cooled to 120 ° C, and the synthetic drying oil fatty acid (trade name: Heidiene, Soken Chemical Co., Ltd.)
(Manufactured by K.K.) 140.0 g, hydroquinone 8.8 g and ethyl cellosolve 61.1 g were added and reacted at 150 ° C. for 2 hours, then cooled to 120 ° C. and 43.2 g of acrylic acid was added and reacted at 120 ° C. for 4 hours. Then, a resin solution (A ₂ ) of the component A of the present invention was produced.

This product has an amine value of 99.0mmol / 100g and an acid value of 9.9m.
mol / 100 g, and the solid content concentration was 75% by weight.

Production Example 3 The following compound obtained by reacting bisphenol A and epichlorohydrin in the presence of an alkali catalyst As a product, 1,000 g of a bisphenol type epoxy resin having an epoxy equivalent of 950 (trade name: Epicoat 1004 manufactured by Yuka Shell Epoxy Co., Ltd.) was added to ethyl cellosolve 24
Dissolved in 7.4g, acrylic acid 77.5g, hydroquinone 1
0 g and 5 g of N, N dimethylaminoethanol were added, and the mixture was heated to 105 ° C. and reacted for 5 hours.
A resin solution (B ₁ ) of (B) was synthesized.

Production Example 4 Compound shown below obtained by reacting bisphenol A and epichlorohydrin in the presence of an alkali catalyst As the bisphenol type epoxy resin having an epoxy equivalent of 950 (trade name: Epicoat 1004 manufactured by Yuka Shell Cepoxy Co., Ltd.), 1,000 g of ethyl cellosolve 3
Dissolved in 83 g, 148.4 g of dehydrated castor oil fatty acid, 38.2 g of acrylic acid, 12 g of hydroquinone and 6 g of N, N-dimethylaminoethanol were added, heated to 100 ° C. and reacted for 6 hours, and then the component (B) of the present invention Of the resin solution (B ₂ ) was synthesized.

Example 1 After 400 g of (A ₁ ) produced in Production Example 1 and 240 g of (B ₁ ) produced in Production Example 4 were mixed until uniform,
As component (C), 7.2 g of dehydrated castor oil fatty acid was added, and further 8.6 g of acetic acid was added, and the mixture was thoroughly stirred and neutralized. Next, deionized water was gradually added to prepare an aqueous solution having a solid content concentration of 20% by weight.

2,000 g of this 20% by weight aqueous solution, 4 g of carbon black, 20 g of basic lead silicate and 2,000 glass beads
0 g was placed in a 5 stainless beaker and vigorously stirred for 2 hours with a high speed rotating mixer, and then glass beads were filtered. Next, deionized water containing 0.32 g of manganese acetate as manganese metal was added so that the solid content concentration became 16.5% by weight to prepare an electrodeposition coating solution.

Using the above electrodeposition coating solution as a carbon electrode as an anode, a zinc phosphate treated plate (Japan Test Panel Co., Bt3004, 0.
Cathode deposition type electrodeposition coating was performed using (8 × 70 × 150 mm) as a cathode. The test results are shown in Table-1.

Example 2 A cathodic electrodeposition coating solution was prepared under exactly the same conditions as in Example 1 except that cobalt acetate was used instead of manganese acetate so that the amount of metal was the same as that of manganese, and Example 1 was used. The test is performed under the same conditions as above and the results are displayed.
Shown in 1.

Example 3 A cathodic electrodeposition coating solution was prepared under exactly the same conditions as in Example 1 except that 9.6 g of tung oil oil fatty acid was used as the component (C) instead of dehydrated castor oil fatty acid, and the same conditions as in Example 1 were used. The results are shown in Table-1.

Comparative Example 1 A cathodic deposition type electrodeposition coating solution was prepared under exactly the same conditions as in Example 1 except that the component (C) was not added, and the test was conducted under the same conditions as in Example 1 and the results are shown in Table 1. .

Example 4 400 g of (A ₂ ) produced in Production Example 2 and 400 g of (B ₂ ) produced in Production Example 4, and a synthetic drying oil fatty acid (trade name Heidien, manufactured by Soken Chemical Industry Co., Ltd.) as the component (C) 12
After mixing g until uniform, 9.6 g of acetic acid was added and the mixture was thoroughly stirred and neutralized. Next, deionized water was gradually added to prepare an aqueous solution having a solid content concentration of 25% by weight. 1,000 g of this 25% by weight aqueous solution, 2.5 g of carbon black, 25 g of basic lead silicate and 1,000 g of glass beads are added.
The mixture was placed in a stainless beaker and stirred vigorously with a high-speed rotary mixer for 2 hours, and then the glass beads were filtered. Next, deionized water containing 0.13 g of manganese acetate as manganese metal was added so that the solid content concentration was 18% to prepare an electrodeposition coating solution.

Using the above electrodeposition coating solution as a carbon electrode as an anode, a zinc phosphate treated plate (Japan Test Panel Co., Bt3004, 0.
8 × 70 × 150 mm) was used as a cathode, and cathodic deposition type electrodeposition coating was performed. The test results are shown in Table-2.

Comparative Example 2 As a component (C), a synthetic drying oil fatty acid (trade name: Hydiene,
Example 4 was used to prepare a cathodic deposition type electrodeposition coating solution under exactly the same conditions as in Example 4 except that Soken Chemical Co., Ltd.) was not added.
The test was conducted under the same conditions as in Table 2 and the results are shown in Table 2.

(Effect of the invention) As is clear from the results of Table 1 and Table 2, by adding an unsaturated carboxylic acid at the time of preparing the electrodeposition coating solution, the baking temperature is lowered, that is, low temperature curable cathodic deposition. A type electrodeposition coating composition could be obtained.

Continued Front Page (72) Inventor Yasuyuki Tsuchiya 3-8-23 Asahi Kusuha, Hirakata City, Osaka Prefecture

Claims (1)

[Claims] 1. A polymer compound having (A) (1) a carbon-carbon double bond having a molecular weight of 500 to 5,000 and an iodine value of 50 to 500, and 3 to 12% by weight of oxirane oxygen. 30 to 300 millimoles per 100 g of the molecular compound, the general formula [Wherein R ₁ and R ₂ represent a hydrocarbon having 1 to 20 carbon atoms, a part of which may be substituted with a hydroxyl group, provided that R ₁ and R ₂ may have a ring structure, The structure may contain unsaturated groups. ] And (3) 0 to 200 per 100 g of the polymer compound of (1) above
Millimolar, general formula [In the formula, R ₃ and R ₄ represent a hydrogen atom or a methyl group. ] Α, β unsaturated carboxylic acid or molecular weight 1 represented by
100 parts by weight of a reaction product of an unsaturated fatty acid having a carbon-carbon conjugated double bond in an amount of 0 to 350 and 10% by weight or more, or a mixture thereof, (B) the general formula [In the formula, R ₅ and R ₆ are a hydrogen atom or a methyl group, and n is 0.
To 20 preferably represent an integer of 1 to 10] and 1.9 to 2.1 mol of the general formula per molecule of the diglycidyl compound. [In the formula, R ₃ and R ₄ represent a hydrogen atom or a methyl group. ] Α, β unsaturated carboxylic acid or molecular weight 1 represented by
10-200 parts by weight of a reaction product of an unsaturated fatty acid having a carbon-carbon conjugated double bond of 10 wt% or more at 0 to 350, or (C) an unsaturated monocarboxylic acid having 6 to 24 carbon atoms, or 0.1-10 parts by weight of the dimer thereof, (D) 0.005-1.0 parts by weight (as metal amount) of a water-soluble salt of an organic acid of a metal selected from manganese, cobalt and copper are essential components. A cathodic deposition type electrodeposition coating composition having excellent low temperature curability, which is contained as.