JP3108513B2 - Electrodeposition coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition coating composition capable of forming a coating film having particularly excellent rust prevention properties.

[0002]

2. Description of the Related Art Electrodeposition paints have excellent throwing power and can form a coating film having excellent properties such as durability and corrosion resistance. For example, it is widely used for painting automobile bodies, painting electric appliances, and the like.

[0003] Electrodeposition paints are often blended with rust preventive pigments, such as lead compounds such as lead chromate, basic lead silicate and strontium chromate, and chromium compounds in order to further improve the corrosion resistance. However, the compound is a very harmful substance, and its use is problematic in terms of pollution control.
Therefore, as non-toxic or low-toxic rust preventive pigments replacing the lead compounds and the like, conventionally, zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, zinc molybdate, calcium molybdate, zinc oxide, iron oxide, phosphomolybdenum The use of aluminum phosphate, zinc phosphomolybdate, etc. has been studied, but these compounds do not have the rust-preventing ability of the above-mentioned lead compounds and chromium compounds. It is unstable and not practically satisfactory.

[0004]

SUMMARY OF THE INVENTION The main object of the present invention is to form a coating film having the same or better anticorrosive properties without using the above-mentioned rust-preventive pigment which has a problem in pollution control. To provide an electrodeposition coating composition that can be used.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on metal species which exhibit excellent rust-preventive performance equivalent to or higher than lead compounds and chromium compounds in electrodeposition paints. It has been found that the incorporation of the bismuth compound and the organotin compound into an electrodeposition paint can provide an electrodeposition coating film having extremely excellent anticorrosion properties, thereby completing the present invention.

That is, the present invention relates to (A) at least one bismuth compound selected from bismuth silicate, triphenyl bismuth and bismuth gallate, and (B) an alkyltin ester of an organic tin oxide or an aliphatic dicarboxylic acid. An object of the present invention is to provide an electrodeposition coating composition characterized by containing at least one organic tin compound selected from compounds.

The bismuth compound (A) used in the present invention is at least one selected from inorganic bismuth silicate, organic triphenylbismuth, and bismuth gallate. These can be used alone or in combination of two or more.

The organotin compound (B) used in the present invention is at least one selected from organic tin oxides and alkyltin ester compounds of aliphatic dicarboxylic acids. Examples of the organic tin oxide include dibutyltin oxide (DBTO) and dioctyltin oxide (DOT).
O) and the like, which are hardly soluble in solvents such as powders, and examples of the alkyltin ester compound of an aliphatic dicarboxylic acid include dibutyltin dilaurate (DBTDL), dioctyltin dilaurate (DOTDL), and dibutyltin diacetate ( DBTDA) and the like.

The amount of the above (A) and (B) can be varied over a wide range with respect to the solid content of the paint.
Usually, each (A) is preferably in the range of 0.1 to 10% by weight, particularly 0.5 to 2% by weight in terms of metal, and (B)
Is suitably 1 to 10% by weight.

The above (A) and (B) can be introduced into the electrodeposition coating composition by blending (A) a dispersing resin and an enamelled composition.
When (B) is in powder form, it is preferable to mix a dispersing resin and an enamelled one in the same manner as in (A), and when (B) is in a liquid form, it should be mixed when preparing a resin emulsion. Can be performed. As the dispersing resin, those listed below can be used as a base resin for an electrodeposition coating material, and in particular, for the cationic type, an epoxy tertiary amine type, an acrylic quaternary ammonium salt type, an epoxy quaternary. Ammonium salt type resins are exemplified.

The enamelling of the above (A) and (B) with the dispersing resin can be carried out in the same manner as in the case of blending pigments into a usual electrodeposition coating composition. ) And (B) can be dispersed in a dispersion mixer such as a ball mill together with a dispersing resin or the like to prepare a paste. At that time, pigments may be dispersed together with the above (A) and (B). Such a prepared pigment paste can be blended with a binder (vehicle) resin component for paints and the like, and by sufficiently pulverizing the powders of (A) and (B), an improvement in anticorrosive ability and catalytic ability can be expected. .

As the pigments that can be dispersed together with the above (A) and (B), any pigment can be used without particular limitation as long as it is a pigment usually used in electrodeposition paints. For example, titanium oxide, carbon black, Coloring pigments such as redwood; extenders such as clay, mica, barita, talc, calcium carbonate, and silica; and rust preventive pigments such as aluminum phosphomolybdate and aluminum tripolyphosphate.

The electrodeposition coating composition of the present invention may be either of an anionic type or a cationic type. In general, the cationic type is preferred from the viewpoint of corrosion resistance. Any of polybutadiene-based, alkyd-based, and polyester-based resins can be used, and among them, a polyamine resin represented by, for example, an amine-added epoxy resin is preferable.

Examples of the amine-added epoxy resin include (i) adducts of polyepoxide compounds with primary mono- and polyamines, secondary mono- and polyamines, or mixed primary and secondary polyamines (for example, US Pat. 988,
(Ii) adducts of polyepoxide compounds with secondary mono- and polyamines having a ketiminated primary amino group (see, for example, U.S. Pat.
(Iii) a reaction product obtained by etherification of a polyepoxide compound with a ketiminated hydroxy compound having a primary amino group (see, for example, JP-A-59-43013). .

The polyepoxide compound used for producing the above amine-added epoxy resin is a compound having two or more epoxy groups in one molecule.
0, preferably 400 to 4,000, more preferably 8
Those having a number average molecular weight in the range of 00 to 2,000 are suitable, and those obtained by reacting a polyphenol compound with epichlorohydrin are particularly preferable. Examples of the polyphenol compound that can be used for forming the polyepoxide compound include bis (4-hydroxyphenyl) -2,2-propane, 4,4-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1,
1-ethane, bis- (4-hydroxyphenyl) -1,
1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, bis (2-hydroxynaphthyl) methane, 1,5-dihydroxynaphthalene, bis (2,4-dihydroxyphenyl) methane, Examples thereof include tetra (4-hydroxyphenyl) -1,1,2,2-ethane, 4,4-dihydroxydiphenyl sulfone, phenol novolak, and cresol novolak.

The polyepoxide compound may be partially reacted with a polyol, a polyether polyol, a polyester polyol, a polyamidoamine, a polycarboxylic acid, a polyisocyanate compound, and the like. Further, ε-caprolactone, an acrylic monomer, etc. May be obtained by graft polymerization.

The above-mentioned base resin may be any of an external cross-linking type and an internal (or self-cross-linking) type resin. ) Can be a conventionally known crosslinking agent such as a polyisocyanate compound or an amino resin,
Particularly, a blocked polyisocyanate compound is preferred. Further, as the internal cross-linkable resin, a resin into which a blocked polyisocyanate type is introduced is preferable.

The above-mentioned blocked isocyanate compound which can be used in the external crosslinking type can be an addition reaction product of a stoichiometric amount of a polyisocyanate compound with an isocyanate blocking agent. Examples of the polyisocyanate compound include aromatic, alicyclic or aliphatic such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, bis (isocyanatomethyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, and isophorone diisocyanate. Group polyisocyanate compounds and excess amounts of these isocyanate compounds in ethylene glycol, propylene glycol,
Terminal isocyanate-containing compounds obtained by reacting low-molecular-weight active hydrogen-containing compounds such as trimethylolpropane, hexanetriol, and castor oil.

On the other hand, the isocyanate blocking agent is one that blocks by adding to the isocyanate group of the polyisocyanate compound. It is preferable that the blocking agent be dissociated to regenerate a free isocyanate group. Examples of the blocking agent satisfying such requirements include lactam compounds such as ε-caprolactam and γ-butyrolactam; methyl ethyl ketoxime;
Oxime compounds such as cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol; aliphatic alcohols such as n-butanol and 2-ethylhexanol; aromatics such as phenylcarbinol and methylphenylcarbinol Alkyl alcohols; ether alcohol compounds such as ethylene glycol monobutyl ether;

Of these, oxime-based and lactam-based blocking agents are particularly suitable from the viewpoint of curability of the electrodeposition coating composition, since they are blocking agents that dissociate at a relatively low temperature.

The method for introducing a blocked isocyanate group into a base resin in a type in which a blocked isocyanate group is contained in a base resin molecule and self-crosslinking can be performed by a conventionally known method, for example, a partially blocked polyisocyanate compound. It can be introduced by reacting a free isocyanate group therein with an active hydrogen-containing portion in the base resin.

In the case of a cationic resin, the base resin is usually neutralized and made water-soluble by neutralizing the resin with a water-soluble organic acid such as formic acid, acetic acid, or lactic acid. In the case of an anionic resin, it can be carried out by neutralizing with an alkali such as an amine or an alkali metal hydroxide instead of a water-soluble organic acid, and dissolving and dispersing in water. .

The electrodeposition coating composition of the present invention may optionally contain paint additives such as an organic solvent, a pigment dispersant, and a coating surface adjuster.

The electrodeposition coating composition of the present invention can be applied to a desired substrate surface by electrodeposition coating. In general, the electrodeposition coating is diluted with deionized water so that the solid content concentration is about 5 to 40% by weight, and the pH is further adjusted to 5.5 to 9.0.
The electrodeposition bath composed of the electrodeposition coating composition of the present invention adjusted to the range described above is usually adjusted to a bath temperature of 15 to 35 ° C., and a load voltage of 1
It can be carried out under the condition of 00 to 400V.

The thickness of the electrodeposited coating film that can be formed using the composition of the present invention is not particularly limited, but is generally preferably in the range of 10 to 40 μm based on the cured coating film. The baking and curing temperature of the coating film is generally 100 to 2
A temperature in the range of 00 ° C is suitable.

[0026]

According to the present invention, a bismuth compound (A) and an organotin compound (B) are blended into an electrodeposition coating composition to provide a rust-preventive pigment such as a lead compound which is problematic in terms of pollution control. The present invention can provide an electrodeposition coating composition that provides an electrodeposition coating film having excellent rust-prevention properties substantially equal to or higher than the case where the rust-prevention pigment is blended, without using the same.

Although it is not clear why such an excellent rustproofing property is obtained in the electrodeposition coating composition of the present invention,
It is presumed that the bismuth compound (A) has some action at the interface with the surface to be coated.

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Note that “parts” and “%” indicate “parts by weight” and “% by weight”.

Production of Pigment Paste Each of the components shown in Table 1 below was added to a ball mill and subjected to dispersion treatment for 40 hours to obtain pigment pastes of formulations 1 to 7.

[0030]

[Table 1]

Example 1 1,900 parts of Epon 1004 (* 3) were dissolved in 1,012 parts of butyl cellosolve, and 124 parts of diethylamine were dissolved in 8 parts of 8 parts.
After dropping at 0 to 100 ° C, the mixture was kept at 120 ° C for 2 hours to obtain an epoxy resin-amine adduct having an amine value of 47.

Next, 1,000 parts of a dimer acid type polyamide resin having an amine value of 100 (trade name "Versamide 460", manufactured by Henkel Hakusui Co., Ltd.) is dissolved in 429 parts of methyl isobutyl ketone and heated to 130 to 150 ° C. under reflux. Then, the produced water was distilled off, and the terminal amino group of the amide resin was changed to ketimine. This is kept at 150 ° C. for about 3 hours, and cooled to 60 ° C. after the distillation of water is stopped. This was then added to the epoxy resin-amine adduct to add 1
Heat to 00 ° C., hold for 1 hour, cool to room temperature
A varnish of 8% epoxy resin-amino-polyamide addition resin with an amine value of 65 was obtained.

103 parts of the varnish obtained above (70 parts in solid content of resin), 30 parts of 2-ethylhexyl alcohol blocked product of xylylene diisocyanate (in solid content), 1 part
After 15 parts of 0% acetic acid was blended and uniformly stirred, 150 parts of deionized water was added dropwise over about 15 minutes with vigorous stirring to obtain a cationic electrodeposition clear emulsion having a solid content of 33.6%. To 298 parts of this clear emulsion, 36.3 parts of a pigment paste having the formulation shown in Formula 1 of Table 1 was added with stirring, and diluted with 271.3 parts of deionized water to obtain a cationic electrodeposition paint. (* 3) Epon 1004: a bisphenol A type epoxy resin having an epoxy equivalent of about 950, manufactured by Yuka Shell Epoxy.

Examples 2 and 3 and Comparative Examples 1 to 3 In Example 1, the pigment pastes having the formulations shown in Formulations 2, 3 and 5 to 7 in Table 1 were used instead of the pigment paste of Formulation 1, respectively. The same operation as in Example 1 was performed to obtain a cationic electrodeposition paint shown in Table 1.

Example 4 The same procedure as in Example 1 was carried out except that the pigment paste shown in Formulation 4 in Table 1 was used instead of the pigment paste of Formulation 1 in Example 1, and 2 parts of dibutyltin dilaurate was added during the preparation of the clear emulsion. Was carried out to obtain a cationic electrodeposition coating material of Example 4.

Coating test The electrodeposition paints obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to a chemical conversion treatment with Palbond # 3030 (Zinc phosphate treating agent, manufactured by Nippon Parkerizing Co., Ltd.). 70mm
Was subjected to electrodeposition coating using the cold-rolled dull steel plate as a cathode. The electrodeposition conditions were as follows: a voltage of 300 V, an electrodeposited film having a thickness of about 20 μm (based on the dry film thickness) was formed, washed with water, and baked. The baking was performed using an electric hot air drier with an atmosphere temperature of four stages and a baking time of 20 minutes. Table 2 shows the performance test results of the obtained coated plate.

[0037]

[Table 2]

The performance test was performed according to the following method. (* 4) Corrosion protection: Cross-cut scratches were made on the electrodeposited coating with a knife to reach the substrate, and this was JIS Z2371.
A salt spray test was conducted for 840 hours in accordance with the above, and the evaluation was made by rust from knife scratches and blister width. A: The maximum width of rust or blisters is less than 1 mm from the cut part (one side). ○: The maximum width of rust or blisters is 1 mm or more from the cut part 2
Less than mm (one side). △: The maximum width of rust or blisters is 2 mm or more from the cut part 3
Less than mm (one side) and the blisters are quite noticeable on the flat surface. ×: The maximum width of rust or blisters is 3 mm or more from the cut portion and blisters are observed on the entire coated surface.

(* 5) Curability: The coating surface obtained by rubbing the coated surface of each of the obtained electrodeposition coated plates 20 times back and forth with a length of about 3 to 4 cm using a gauze soaked with methyl isobutyl ketone for 20 times. The surface appearance was visually evaluated. ：: No scratch is observed on the painted surface. Δ: Scratch is observed on the painted surface, but the base is not visible. ×: The coating film was dissolved, and the substrate was visible.

(* 6) Impact resistance: Using a DuPont impact tester, the diameter of the hammer was 1/2 inch, the falling weight height was 50 cm,
The test was performed under the conditions of a measurement atmosphere of 20 ° C., and the recessed parts subjected to impact were visually evaluated. ：: No abnormality. Δ: Some small cracks are observed. X: Large cracks are observed.

(* 7) 3-coat sharpness: on the electrodeposition coated surface,
Amino alkyd intermediate coating “Amirac TP-37 Gray” manufactured by Kansai Paint Co., Ltd. is applied by spray coating to a dry film thickness of about 35 μm, baked at 140 ° C. for 20 minutes, and then further Kansai Paint Co., Ltd. Amyl alkyd-based top coating “Amirac TM13 White” was spray-coated to a dry film thickness of about 35 μm and baked at 140 ° C. for 20 minutes. Was used for evaluation. ◎: measured value of 80 or more ○: measured value of 75 or more and less than 80 Δ: measured value of 70 or more and less than 75 ×: measured value of less than 70

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C09D 5/44 C09D 7/12 C09D 201/00-201/10 CAPLUS (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A compound selected from (A) at least one bismuth compound selected from bismuth silicate, triphenylbismuth and bismuth gallate, and (B) an organic tin oxide or an alkyltin ester compound of an aliphatic dicarboxylic acid. An electrodeposition coating composition comprising at least one type of organotin compound. 2. The electrodeposition coating composition according to claim 1, wherein the bismuth compound (A) and the organotin compound (B) are enameled and contained in a dispersing resin.