JP2002088301A - Electrodeposition coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrodeposition coating material excellent in film formability even after long storage, capable of forming a film excellent in smoothness rustproofness, and the like. SOLUTION: This electrodeposition coating material is characterized by containing a polyester compound obtained by reacting a 2-3C aliphatic glycol, an aliphatic dicarboxylic acid and an aliphatic monoalcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition paint capable of forming a film having excellent film forming properties and excellent properties such as smoothness and rust prevention even after being stored for a long period of time.

[0002]

2. Description of the Related Art Cationic or anionic electrodeposition coatings contain little organic solvent and are suitable for environmental measures such as pollution prevention, and have excellent throwing power.
In particular, cationic electrodeposition paints are widely used as undercoat paints for conductive metals such as automobile bodies because they form a coating film having excellent durability and anticorrosion properties.

[0003] In order to maintain the film forming property of the coating film, a low boiling organic solvent having a boiling point of about 120 ° C or less (eg, methyl isobutyl ketone (116 ° C), methyl ethyl ketone (80 ° C)) is usually used for the electrodeposition paint. Etc.), boiling point of 120-20
A hydrophilic solvent at 0 ° C. (for example, butyl cellosolve (171)
° C), propylene glycol monomethyl ether (12
1 ° C.) or a low-molecular-weight soft resin having a molecular weight of 4000 or less (eg, xylene resin, polypropylene glycol, etc.). However, electrodeposition paints containing such substances, when stored for a long time,
Its film-forming properties (coating ability) gradually decrease, making it difficult to apply a coating to a predetermined thickness, and furthermore, gradually reducing the smoothness of the coated surface. Alternatively, the inclusion of a hydrophilic solvent is not preferable because it goes against reducing VOC (reducing the content of volatile organic compounds).

[0004] On the other hand, in order to reduce VOC, removal of volatile components such as organic solvents contained in electrodeposition coating materials to, for example, 1% by weight or less is performed by vacuum distillation or the like. However, in this case, the film-forming property is reduced, and it is difficult to apply a film having a thickness of 15 μm or more with a cured coating film, and the smoothness and corrosion resistance of the coating film may be reduced. In addition, the electrodeposition paint is applied to an alloy-plated steel sheet (steel coated with an alloy plating of zinc and iron) which is widely used as a base material for automobile outer panels, etc. When the voltage is increased, gas is generated to form a pinhole (generally called a gas pin), which causes a defect that the smoothness of the coating film is reduced.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a film having a low volatile organic solvent content, a good film-forming property and a thickness of 15 μm.
An object of the present invention is to provide an electrodeposition paint, particularly a cationic electrodeposition paint, which can be easily applied to the above thick film and which can be applied to an alloy-plated steel sheet without generating gas pins even when the electrodeposition is applied. .

As a result of intensive studies, the present inventors have now found that the above object can be achieved by adding a specific polyester compound to the electrodeposition paint, and have completed the present invention. Was.

[0007] Thus, the present invention provides an electrodeposition paint characterized by containing a polyester compound obtained by reacting an aliphatic glycol having 2 to 3 carbon atoms, an aliphatic dicarboxylic acid and an aliphatic monoalcohol. Things.

Hereinafter, the electrodeposition paint of the present invention (hereinafter referred to as the present paint) will be described in more detail.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester compound used in the present coating composition is obtained by reacting an aliphatic glycol having 2 to 3 carbon atoms, an aliphatic dicarboxylic acid and an aliphatic monoalcohol. C 2-3 used here
Examples of the aliphatic glycol include ethylene glycol, propylene glycol, 1,3-propanediol and the like, and these can be used alone or in combination of two or more. As the aliphatic dicarboxylic acid, a compound having two carboxyl groups in one molecule and having 2 to 6 carbon atoms in a portion excluding the carboxyl group can be suitably used. Specifically, for example, Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid and the like, each of which alone or
It can be used in combination of more than one species. Of these, adipic acid is economical and preferred for work. Further, as the aliphatic monoalcohol, a monoalcohol having 4 to 13 carbon atoms is preferable, for example, butyl alcohol, hexyl alcohol, octyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, tridecanol, tridecanol, and the like. These can be used alone or in combination of two or more. Of these, 2-ethylhexyl alcohol, isononyl alcohol and tridecyl alcohol are particularly preferred.

The polyester compound used in the present coating composition is obtained by subjecting the aliphatic glycol having 2 to 3 carbon atoms, aliphatic dicarboxylic acid and aliphatic monoalcohol to an esterification reaction according to a method known per se, The polyester compound thus obtained preferably has a number average molecular weight in the range of generally 300 to 2,000, especially 500 to 1500.

Examples of the electrodeposition paint containing the polyester compound according to the present invention include known cationic electrodeposition paints and anion electrodeposition paints.

Examples of the cationic electrodeposition paint include an aqueous dispersion or an aqueous solution mainly containing a cationic resin having both a crosslinkable functional group such as a hydroxyl group and a cationic group and a crosslinking agent.

The resin constituting the main skeleton of the cationic resin includes, for example, epoxy resin, acrylic resin, polybutadiene, alkyd resin, polyester resin and the like. Among them, a cationic resin obtained by using an epoxy resin and adding an amine to the epoxy resin is preferable because of its excellent anticorrosion property.

Examples of the cationic resin obtained by adding an amine to an epoxy resin include, for example, adducts of an epoxy compound with a primary mono- or polyamine, a secondary mono- or polyamine, and a mixed primary and secondary polyamine ( For example, see U.S. Pat. No. 3,984,299); an epoxy compound and a secondary mono-containing ketiminated primary amino group.
Or an adduct with a polyamine (eg, US Pat. No. 401)
7438); a reaction product obtained by etherification of an epoxy compound and a ketiminated hydroxyl compound having a primary amino group (for example, JP-A-59-4).
No. 3013).

The above epoxy compound has one epoxy group.
A compound having at least two in the molecule, usually having a number average molecular weight of 400 to 4000, particularly 800 to 20
00 and the epoxy equivalent is 190-20.
Those in the range of 00, especially 400 to 1000 are suitable. Such an epoxy compound can be obtained by, for example, a reaction between a polyphenol compound and epilolhydrin. Examples of the polyphenol compound include bis (4-hydroxyphenyl) -2,2-propane and 4,4-dihydroxybenzophenone, bis (4-
Hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-
(Hydroxy-tert-butylphenyl) -2,2-propane, bis (2-hydroxynaphthyl) methane,
5-dihydroxynaphthalene, bis (2,4-dihydroxyphenyl) methane, tetra (4-hydroxyphenyl) -1,1,2,2-ethane, 4,4-dihydroxydiphenylsulfone, phenol novolak, crezo-
Lunovolak and the like.

On the other hand, examples of the crosslinking agent used in combination with the cationic resin include a block polyisocyanate compound and an amino resin. As the block polyisocyanate compound, polyisocyanate
Preferably, substantially all isocyanate groups in the compound are blocked by an addition reaction with a blocking agent, wherein the polyisocyanate compound is a compound having at least two isocyanate groups in one molecule. And
Aromatic, alicyclic and aliphatic polyisocyanate compounds known per se, and polyisocyanate compounds thereof
And a prepolymer having a terminal isocyanate group obtained by reacting an excess amount of the compound with a low molecular weight active hydrogen-containing compound such as glycol or triol. As blocking agents, for example, lactams, oximes,
Known compounds such as phenols, aliphatic alcohols, aromatic alkyl alcohols and ether alcohols can be used.

The use ratio of the cationic resin and the crosslinking agent is as follows:
Generally, based on the total solids weight of both components, the cationic resin is in the range of 50-90%, especially 65-80%, and the crosslinker is in the range of 50-10%, especially 35-20%. Are suitable. The cationic resin can be solubilized or dispersed in water by neutralizing with a water-soluble organic acid such as formic acid, acetic acid, or lactic acid.

The method of compounding the polyester compound into the cationic electrodeposition coating composition is not particularly limited. For example, a pigment may be previously mixed with a cationic resin or a crosslinking agent, or may be mixed at the time of emulsifying and mixing the cationic resin and the crosslinking agent. It can be performed by mixing at the time of dispersion. The compounding amount of the polyester compound is usually 10% of the resin solid content of the cationic electrodeposition paint.
A suitable range is 0.5 to 20 parts by weight, especially 1 to 10 parts by weight, per 0 parts by weight.

In the cationic electrodeposition paint, if necessary, a coloring pigment, a rust-preventive pigment, an extender pigment, an organic solvent, an anti-cissing agent, a surfactant, a catalyst, an inhibitor, a rheological agent may be used.
A control agent, a pigment dispersant and the like can be appropriately contained.

Among them, examples of the rust-preventive pigment include zinc powder, zinc phosphate, calcium phosphate, aluminum phosphate, aluminum polyphosphate such as aluminum tripolyphosphate, aluminum orthophosphate, calcium orthophosphate. , Boric acid based rust preventive pigments, alkaline earth metals,
A composite oxide of iron oxide or at least one selected from zinc oxide or the like, and a tungstic acid-based rust preventive pigment,
A phosphite-based rust preventive pigment, a hypophosphite-based rust preventive pigment, a nitrite-based rust preventive pigment, a vanadic acid-based rust preventive pigment, zinc formate, zinc acetate, zinc octenoate, and the like can be used. _{Further, Zr (OH) 4, Mg} 4 Al 2 (OH) 12 CO 3 · 3H 2
_{O, Mg 6 Al 2 (OH} ) 16 CO 3 · 5H 2 O, Mg 6 Al 7
Compounds such as (OH) ₁₆ CO ₃ .4H ₂ O and also bismuth lactate bismuth silicate, triphenyl bismuth, bismuth gallate, bismuth hydroxide bismuth trioxide, bismuth nitrate, bismuth benzoate, bismuth citrate, oxycarbonate Bismuth-containing compounds such as bismuth can also be used as rust preventive pigments.

The cationic electrodeposition coating composition of the present invention containing a polyester compound has a solid content of 5 to 40% by weight, preferably 10 to 25% by weight, for example, by adding deionized water, and has a pH of 5 to 25% by weight. 0.5-9, preferably 5.5
The electrodeposited bath is adjusted to ~ 7, and the bath temperature is 15 to 35 ° C, the load voltage is 100 to 400V, and the object to be coated is immersed as a cathode and energized to carry out cationic electrodeposition coating. After energization, the object to be coated is pulled up from the electrodeposition bath, washed with water, and then heated at about 100 to about 200 ° C., preferably about 140 to about 180 ° C. for about 10 to 40 minutes to cure the coating. . Its film thickness is 5-100μ with cured coating
m, particularly preferably 15 to 40 μm. The cationic electrodeposition paint of the present invention containing a polyester compound,
Even when coated on an alloy-plated steel sheet, a film thickness of 15 μm or more based on the cured coating film can be easily obtained without generating gas pins or the like.

On the other hand, as the anionic electrodeposition paint which can contain the polyester compound according to the present invention,
For example, a known anionic electrodeposition coating composed of an aqueous dispersion or an aqueous solution containing a neutralized anionic resin having a carboxyl group and a crosslinking agent as main components can be used.

As the anionic resin, those known per se which are blended in ordinary anionic electrodeposition paints can be used. In particular, when an anionic acrylic resin having a carboxyl group and a hydroxyl group is used, It is preferable because an electrodeposition paint that forms a coating film having excellent weather resistance and smoothness can be obtained. Also, as an anionic resin,
Polyester resin having a carboxyl group and a hydroxyl group,
Polyurethane resin, vinyl resin and the like can also be used.

In the anionic resin, the carboxyl group is converted to ammonia, diethylamine, ethylethanolamine,
Neutralizing agents such as organic amines such as diethanolamine, monoethanolamine, monopropanolamine, isopropanolamine, ethylaminoethylamine, hydroxyethylamine and diethylenetriamine, and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. By neutralizing, it can be made water-soluble or water-dispersed.

These anionic resins generally have about 1
An acid number in the range of 0 to about 200 mg KOH / g and about 3
It preferably has a hydroxyl number in the range of 0 to about 300 mg KOH / g. In addition, the anionic resin is 1000
It is preferable to have a number average molecular weight of 0 or less, especially in the range of 4000 to 8000.

Examples of the crosslinking agent used in combination with the anionic resin include a melamine resin, a block polyisocyanate compound and a polyoxazoline compound. Among them, the melamine resin is particularly preferred.

As the melamine resin, part or all of the methylol group of methylol melamine obtained by reacting melamine with formaldehyde or the like is modified with at least one kind of monovalent alcohol having 1 to 10 carbon atoms. Other etherified melamine resins can be used.
Preferably, the melamine resin has a mononuclear to polynuclear (about 2 to about 5) nucleus occupying 50% by weight or more.
The melamine resin may contain one having an imino group, a methylol group, or another functional group.

The block polyisocyanate compound is obtained by blocking the isocyanate group of the polyisocyanate compound with a blocking agent. Specifically, the compounds exemplified for the cationic electrodeposition coating are preferably used. can do. When heated, the blocking agent dissociates and free isocyanate groups are regenerated, which undergoes a cross-linking reaction with active hydrogen such as hydroxyl groups in the anionic resin.

The use ratio of the anionic resin and the crosslinking agent is as follows:
Generally, based on the total solids weight of the two components, the anionic resin is 50-90% by weight, especially 60-80% by weight, and the crosslinking agent is 50-10% by weight, especially 40-20% by weight.
Suitably, it is in the range of weight percent.

As the anionic electrodeposition coating material, an anionic resin which cross-links and cures by irradiation with active energy rays such as ultraviolet rays, and a coating containing an anionic resin which cross-links and cures by irradiation with ultraviolet rays and heating may be used. it can.

The method of blending the polyester compound into the anionic electrodeposition coating composition is not particularly limited. For example, a pigment which is previously mixed with an anionic resin or a crosslinking agent, or which is mixed at the time of emulsifying and blending the anionic resin and the crosslinking agent. It can be performed by mixing at the time of dispersion. The compounding amount of the polyester compound is usually 100% of the resin solid content of the anionic electrodeposition paint.
A suitable range is 0.5 to 20 parts by weight, especially 1 to 10 parts by weight per part by weight.

The anionic electrodeposition paint may further include, if necessary, a color pigment, a rust preventive pigment, an extender pigment, an organic solvent, a neutralizing acid, a repelling inhibitor, an interface, as described above for the cationic electrodeposition paint. An activator, a catalyst, an inhibitor, a rheological control agent, a pigment dispersant, and the like can be appropriately contained.

The anionic electrodeposition coating composition of the present invention containing a polyester compound is adjusted to a bath solid concentration of 3 to 40% by weight, preferably 5 to 25% by weight, for example, by adding deionized water and the like. 6-9, preferably 6.5-
8. The bath temperature is adjusted to 15 to 40 ° C., preferably 15 to 30 ° C. to form an electrodeposition bath.
Apply a constant DC current of 400V or 1
Anion electrodeposition can be performed by applying a constant voltage or current of 〜400 mA. At that time, a predetermined voltage or current may be applied from the start of energization.
The current may be gradually increased to a predetermined current or a predetermined voltage in 30 seconds. Further, the energization time is suitably about 30 seconds to 5 minutes, and the obtained film thickness is 5 to 100 μm in a cured coating film.
In particular, it is preferably 15 to 40 μm.

After the electrodeposition coating, the object to be coated is pulled up from the electrodeposition bath,
After rinsing, the coating can be cured by heating, irradiating with active energy, or by both heating and irradiation. Curing can be performed by heating at a temperature of about 100 to about 200C, preferably about 120 to about 180C, for about 10 to 60 minutes. On the other hand, examples of the active energy ray include an ultraviolet ray, a laser ray, an X ray, an electron beam, an ion beam ray, and the like.

In order to reduce the content of the volatile organic solvent at the time of application of the present coating composition, the organic solvent (for example, an organic solvent having a boiling point of 130 ° C. or less) contained in the present coating composition is removed in advance by distillation under reduced pressure or the like. Preferably. In order to facilitate the removal under reduced pressure, it is preferable to use a volatile organic solvent having a boiling point of 130 ° C. or lower as an organic solvent used for producing the cationic resin and the anionic resin. Examples of the organic solvent having such a boiling point include methyl ethyl ketone, methyl isobutyl ketone, and isopropanol. Vacuum removal is -700
It is preferable to carry out at a pressure lower than mmHg.

The present coating composition containing a polyester compound has good throwing power (electrocoating) even if the volatile organic solvent content is 1% by weight or less, preferably 0.5% by weight or less. It is possible to form a coating film having excellent film properties and good anticorrosion properties and smoothness. In particular, even in the case of cationic electrodeposition coating on alloy-plated steel sheets, the cured coating
As described above, in particular, it is possible to apply a coating to a thick film of 20 μm or more, and generation of gas pins is not recognized. These properties do not change even after long-term storage of the paint. Thus, according to the present invention, the content of the volatile organic solvent can be reduced to 1% by weight or less without deteriorating the anticorrosion property and the smoothness of the coating film, and a low VOC can be achieved. it can.

The cationic electrodeposition paint and the anion electrodeposition paint of the present coating composition are preferably used as undercoat paints.

[0038]

The electrodeposition coating containing the polyester of the present invention described above does not deteriorate the coating film performance even after being stored for a long period of time, and the volatile organic solvent The content can be halved or less. For example, it can be reduced to 1% by weight or less for cationic electrodeposition paints and 3% by weight or less for anion electrodeposition paints. Without lowering
A film having excellent film-forming properties and good smoothness can be formed. Especially when painting on alloy plated steel sheet,
It is possible to apply a cured film to a thickness of 15 μm or more, particularly 17 to 50 μm, without generating gas pins. As described above, according to the present invention, the content of the volatile organic solvent is reduced to 1 without deteriorating the anticorrosion property and the smoothness.
An electrodeposition coating material having a weight percentage of not more than 10% is provided, and low VOC can be achieved.

[0039]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited thereto. Parts and percentages are in principle on a weight basis, and the film thickness of the coating is based on the cured coating.

1. Sample 1) Electrodeposition paint a): "Epon 1004" (trade name, manufactured by Yuka Shell Co., Ltd.)
Bisphenol A type epoxy resin, epoxy equivalent about 95
0) 1900 parts were dissolved in 1012 parts of methyl isobutyl ketone, heated to 80 to 100 ° C, 124 parts of diethylamine was added dropwise, and then kept at 110 ° C for 2 hours to obtain an amine-added epoxy resin having an amine value of 47. . On the other hand, a dimer-acid type polyamide resin having an amine value of 100 (“BASAMID 460” manufactured by Henkel Hakusui, trade name) 1000
Was dissolved in 429 parts of methyl isobutyl ketone, and 130 parts of
The mixture was heated to reflux and heated to ~ 150 ° C. The product water was distilled off, and the terminal amino group of the amide resin was changed to ketimine. The mixture was kept at 150 ° C for about 3 hours. Cooling. Next, this was added to the above amine-added epoxy resin, heated to 100 ° C., kept for 1 hour, cooled to room temperature, and cooled to room temperature. I got a varnish.

B) "Electron # 7200" (manufactured by Kansai Paint Co., Ltd., 100 parts of an unsaturated resin having an acid value of about 80 mgKOH / g, obtained by reacting maleic anhydride with a mixture of polybutadiene / epoxy resin fatty acid ester / linseed oil) ), 72.5 parts of a pigment paste (Note 1), and then deionized water is added to obtain an anionic electrodeposition paint having a solid content of 13% and a pH of 8.1).

(Note 1) Pigment paste: 5 parts of unsaturated resin (solid content), 10 parts of conductive agent (“Vulcan XC72”),
A paper obtained by adding 3 parts of bismuth hydroxide, 3 parts of dioctyltin oxide and 35 parts of water and mixing and dispersing them.
Strike.

2. Examples and Comparative Examples Examples 1-4, Comparative Examples 1-4 103 parts of varnish for cationic electrodeposition paint (70 parts by resin solid content)
Parts), 30 parts of a 2-ethylhexyl alcohol blocked product of tolylene diisocyanate, and 15 parts of a 10% acetic acid aqueous solution of a polyester compound (the composition and the blending amount are shown in Table 1), and then the mixture was stirred vigorously. While adding 150 parts of deionized water over about 15 minutes, a cationic electrodeposition emulsion having a solid content of 34% was obtained. The emulsion is then depressurized at 30-40 ° C,
"Desolvent" was performed so that the content of the volatile organic solvent in the final cationic electrodeposition coating composition was 5% or less. Thereafter, an emulsion 30 containing the same amount of deionized water as the total amount of the organic solvent and water removed by the desolvent is added.
To 0 parts, 71 parts of a pigment paste (Note 2) were added with stirring, and the mixture was further diluted with deionized water to obtain a cationic electrodeposition paint having a solid content of 20%.

(Note 2) Pigment paste: 5 parts of varnish for cationic electrodeposition paint 2.6 parts of 10% acetic acid aqueous solution, 17 parts of titanium oxide, 2 parts of bismuth hydroxide, 8 parts of purified clay, carbon A dispersion consisting of 0.3 parts of black and 36.5 parts of deionized water. 43% solids content.

Example 5 A resin having a number average molecular weight of 700, a glycol number of 2 and a monoalcohol number of carbon atoms of 100 parts by weight of the resin solid content of the anionic electrodeposition paint was reacted with adipic acid / ethylene glycol / isononyl alcohol. 2 parts of the polyester compound No. 9 were blended to obtain an anionic electrodeposition paint.

Comparative Example 5 An anionic electrodeposition coating material was prepared before blending the same polyester compound as used in Example 5.

3. Performance Test Results Table 1 shows the compositions and performance test results of the electrodeposition coatings obtained in the above Examples and Comparative Examples. The performance test method in Table 1 is as follows.

Volatile organic solvent content : solid content 20
% Of the volatile organic solvent in the cationic electrodeposition paint was measured by gas chromatography. Here, the volatile organic solvent is an organic solvent which is heated at 105 ° C. for 3 hours so that the nonvolatile content becomes 0%. When the diester compound used in the examples is heated under these conditions, the nonvolatile content is 98% or more.

The throwing power : size 70 × 150 × 0.
Four 8 mm steel plates are prepared, and an opening of 8 mm in diameter is provided at the center of three of them. Three steel plates having apertures are arranged at an interval of 20 mm so as to sequentially move away from the anode side, one steel plate having no aperture is placed at the farthest position, and the distance between the foremost steel plate and the anode is 110 mm. did. The side and bottom of the four steel plates arranged in this manner are sequentially surrounded by an insulating plastic sheet, and one box having an open top is provided (however, the outer portions of the first and fourth steel plates have metal parts. It is immersed in an electrodeposition bath, the electrodeposition paint is also allowed to flow into the inside of the box, and the anode side of the steel plate provided with the foreground opening is the A side when viewed from the anode side. ,
The anode side of the farthest steel plate with no opening is G
Face. The thickness (cured coating film) of the electrodeposition coating film on the G side was measured (BOX method). When this film thickness is large, it indicates that the throwing power is good. The electrodeposition conditions are a bath temperature of 28 ° C., a voltage of 250 V, and a conduction time of 180 seconds. Evaluation criteria are
：: The film thickness on the G surface is 10 μm or more, Δ: the film thickness on the G surface is 5 to 9 μm, and X: the film thickness on the G surface is 4 μm or less. This test was performed only for the cationic electrodeposition paint.

Film- forming property : Electrodeposited on a degreased steel sheet at a bath temperature of 28 ° C. and an energizing time of 180 seconds, and after washing with water, 30 ° C. at 170 ° C.
The film thickness (μm) of the coating film formed by curing by heating for a minute was examined. The load voltage at the time of painting was 250 for cationic electrodeposition paint.
V, 150 V for anionic electrodeposition paint.

Gas pinning property : applied to a galvanized steel sheet at a bath temperature of 28 ° C. and a load voltage such that the film thickness of the cured coating film becomes 17 μm, washed with water, heated at 170 ° C. for 30 minutes and cured to 100 cm. ^The number of pinholes generated per ² was examined. ：: No pinhole generated, △: Pinhole 5-1
0 occurrences, ×: occurrence of 10 or more pinholes.

Smoothness : A bath temperature of 28 ° C. was applied to a degreased steel sheet.
The coating was applied at a load voltage such that the film thickness of the cured coating film became 17 μm, washed with water, heated at 170 ° C. for 30 minutes, and the cured coating surface was visually judged. ：: good smoothness, Δ: slightly poor smoothness, ×: very poor smoothness.

In the table, "Initial" means an electrodeposition paint immediately after stirring for 3 days at 30 ° C. after production, and “After storage” means 30 ° C. after production.
Means the electrodeposition paint immediately after open stirring for 10 days.

The compositions of the polyester compounds 1) to 8) in the table are as follows.

1): adipic acid / ethylene glycol /
Produced by reacting propylene glycol / isononyl alcohol, the number average molecular weight is 700, the glycol average carbon number is 2.5, and the monoalcohol carbon number is 9.

2): Adipic acid / propylene glycol / 2-ethylhexyl alcohol is reacted, the number average molecular weight is 1300, the glycol carbon number is 3 and the monoalcohol carbon number is 8.

3): Adipic acid / propylene glycol / isononyl alcohol is reacted, the number average molecular weight is 1,000, the glycol carbon number is 3 and the monoalcohol carbon number is 9.

4): Adipic acid / propylene glycol / tridecyl alcohol is reacted, the number average molecular weight is 800, the glycol carbon number is 3 and the monoalcohol carbon number is 13.

5): adipic acid / ethylene glycol /
It is a polyester diol obtained by reacting propylene glycol, and has a number average molecular weight of 1,000, a glycol average carbon number of 2.5 and a monoalcohol carbon number of 0 (for comparison).

6): Adipic acid / 1,3-butanediol / 2-ethylhexyl alcohol is reacted, the number average molecular weight is 1200, the glycol carbon number is 4 and the monoalcohol carbon number is 8 (for comparison).

7): diethylene glycol monobutyl ether (number average molecular weight 162) (for comparison).

[0062]

[Table 1]

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Katsuhisa Sugizaki, 4-1-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Inside Kansai Paint Co., Ltd. (72) Koji Hirano 4-1-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Inside Nishi Paint Co., Ltd. (72) Inventor Yoshitaka Mizoguchi 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Inside Kansai Paint Co., Ltd. (72) Inventor Akira Tominaga 4-1-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Paint Kansai Paint Co., Ltd. (72) Inventor Kazuo Saito 1-3-3-308 Higashi-Chiba, Chuo-ku, Chiba City, Chiba Prefecture (72) Inventor Akio Ikegami 10-31-20-308 Hatadakita-cho, Sakai-shi, Osaka F-term (reference) 4J038 DD051 NA01 NA03 NA26 PA04

Claims (3)

[Claims] 1. An electrodeposition coating composition comprising a polyester compound obtained by reacting an aliphatic glycol having 2 to 3 carbon atoms, an aliphatic dicarboxylic acid and an aliphatic monoalcohol. 2. A polyester compound comprising 500 to 1500
The electrodeposition coating composition according to claim 1, having a number average molecular weight of: 3. The electrodeposition paint according to claim 1, wherein the aliphatic dicarboxylic acid constituting the polyester compound has 4 to 8 carbon atoms.