JP2695997B2 - Self-deposition type coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a resin film formed by contacting a metal surface, for example, a surface of iron, zinc, an iron alloy or a zinc alloy, with an acidic aqueous solution containing a dispersing resin and an oxidizing agent. The present invention relates to a self-deposition-type coating composition which can efficiently coat and has good stability.

[0002]

2. Description of the Related Art A composition in which a metal surface is brought into contact with an acidic aqueous solution containing a dispersing resin and an oxidizing agent to deposit resin particles on the metal surface and coat the surface is known as a self-deposition coating composition. Japanese Patent Publication No. 47-17630, Japanese Patent Publication No. 48-14412, Japanese Patent Publication No. 52-21006,
JP-B-52-35692, JP-B-53-15093
No., JP-B-53-44949 and JP-A-61-2.
No. 46267 and the like. The formation of the film
By immersing a clean metal surface in the above composition, metal ions are dissolved from the surface, and the ions deposit resin particles continuously on the surface.
It is recognized that, depending on the composition, aggregates are likely to be generated during continuous use, and the stability is poor.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to specify a dispersion resin which is an organic film-forming component in a self-deposition type coating composition, and to form a film efficiently on a metal surface. Another object of the present invention is to provide a self-deposition type coating composition having excellent stability. The specified dispersing resin is to limit the range of the amount of the carboxyl group based on the carboxyl group-containing ethylenically unsaturated monomer and the range of the amount of the nonionic surfactant.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a self-depositing coating composition containing the specified dispersing resin, acid and oxidizing agent. A preferred dispersion resin of the present invention comprises (A) a carboxyl group-containing ethylenically unsaturated monomer;
(B) an ethylenically unsaturated monomer other than the above (A); 90
A nonionic surfactant in a range not exceeding 12% by weight based on the total amount of the monomers (solids) of (A) and (B). It is characterized by.

The above-mentioned carboxyl group-containing ethylenically unsaturated monomers are not specified, but include acrylic acid, methacrylic acid, fumaric acid, maleic acid and the like, and other ethylenically unsaturated monomers are specified. Although not to be mentioned, acrylic acid ester, methacrylic acid ester, acrylamide, acrylonitrile, styrene, vinyl acetate, vinyl chloride, vinylidene chloride and the like, and the dispersing resin for the composition of the present invention is one or more of the above-mentioned compounds. Those containing two or more types can be exemplified as suitable ones.

When the content of the carboxyl group in the dispersion resin which is an organic film forming component is low, for example, the dispersion resin is a polymer comprising less than 2% by weight of a carboxyl group-containing ethylenically unsaturated monomer, and In the coating composition containing the main component, the deposition of the resin particles on the metal surface is reduced, and the formed film becomes thin. On the other hand, when the amount exceeds 10% by weight, the deposition property of the resin particles on the metal surface is improved, but the resin particles tend to be aggregated by metal ions during continuous use, and the stability of the coating composition tends to be poor. It is in. In order to prevent instability due to metal ions, use of a nonionic surfactant can be mentioned.

[0007] The dispersion resin is stabilized by the formation of a hydration layer due to the oxyethylene groups of the activator. Nonionic surfactants used in the present invention are polyoxyethylene nonyl phenol ether, polyoxyethylene uraryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyethylene glycol monolaurate, polyethylene glycol monostearate, Examples include polyethylene glycol distearate. The dispersion resin particles are more stabilized by increasing the content. The activator is usually added during the production of the dispersion resin, but may be added after the production of the dispersion resin or during the preparation of the coating composition for stabilization of the dispersion resin. However, when the content exceeds 12% by weight based on the resin solid content, the formed film tends to be thinner.

In the present invention, an appropriate amount of an anionic surfactant can be further blended for the purpose of maintaining the mechanical stability of the dispersion resin. As the anionic surfactant,
Higher fatty acid salts, higher alcohol sulfates, higher alkyl sulfonates, and the like can be mentioned.

In the present invention, an organic coating can be formed on a metal surface by bringing the metal surface into contact with an aqueous coating composition containing the above-mentioned dispersing resin, acid and oxidizing agent.

The solid content of the resin contained in the coating composition is 5 to 550 g / l, preferably 50 to 100 g / l.
It is. The acid and oxidizing agent to be contained are generally preferably hydrofluoric acid / hydrogen peroxide. The content of hydrofluoric acid is 0.4 to 5.0 g / l, preferably line guard 101.
It contains a sufficient amount of hydrofluoric acid to give an indication of about 200 to about 350 μA on the meter. The management method using the line guard 101 meter is disclosed in U.S. Pat. No. 3,329,587.

The content of hydrogen peroxide is from 0.3 to 3.0 g /
1, preferably containing, for example, a sufficient amount of hydrogen peroxide so that the oxidation-reduction potential value of a coating bath using platinum and a calomel electrode shows a value of about 300 to about 560 mV. A management method for monitoring the oxidation-reduction potential is disclosed in U.S. Pat. No. 4,186,219. Further, the coating composition may contain a metal compound capable of supplying metal ions. The type is not particularly limited as long as it is stable in the coating composition, and its content is about 3.5 g / l or less, preferably about 2.0 g / l or less as metal ions. Further, a pigment can be contained as needed.

[0012]

Next, the present invention will be described with reference to detailed embodiments. Parts in the examples are parts by weight.

(1) Production Example of Dispersion Resin A monomer comprising 2 parts of acrylic acid (2% by weight of component A), 48 parts of methyl methacrylate, and 50 parts of n-butyl acrylate (98% by weight of component B). The mixture was mixed with 2 parts of polyoxyethylene nonylphenyl ether (2% by weight based on the weight of the resin), 1 part of sodium alkylbenzenesulfonate, 0.3 part of ammonium persulfate, and 148.7 parts of water. To produce a dispersed resin 1 having a resin solid content of 40%. In the same way,
Dispersion resins 2 to 6 having the compositions shown in Table 1 and dispersion resins 7 to 11 having the compositions shown in Table 2 were produced.

The test method is described below. (1) Stability of the coating composition Using the dispersion resins 1 to 6, and the dispersion resins 7 to 11,
2 mL of each of the self-deposition type coating composition baths prepared for the coating treatment was collected in a polybeaker, and 20 mL of water was added to prepare a test sample. An aqueous ferric chloride solution (FeCl ₃ .6H ₂ O; 10 g / L) was added dropwise to the prepared sample, and the sample was evaluated in three steps by a titration amount at which the sample began to aggregate. ○: 2 mL or more, Δ: 1.5 to 2 mL, ×: 1.5 mL
Less than. The smaller the titer, the more easily the dispersing resin aggregates during use of the coating composition, and the lower the stability.

(2) Film Formability Using the above-mentioned dispersing resins 1 to 6 and dispersing resins 7 to 11,
Each of the coating composition baths prepared for the coating treatment was applied to 20 to 2 baths.
SPCC (7
× 15 cm size) was immersed for 90 seconds, then washed with water (by immersion), and then dried in an oven at 180 ° C. for 25 minutes to measure the coating thickness.

Example 1 125 g of the above-prepared dispersion resin 1 was put in a coating bath, and deionized water was added with stirring. Then 20% hydrofluoric acid with stirring.
5 ml and 2 ml of 30% hydrogen peroxide were added, and the total amount was adjusted to 11 with deionized water to prepare a bath of the self-deposition type coating composition. The stability and film forming properties are shown in Table 3.

(Examples 2 to 6) In the same manner as in Example 1 described above, coating compositions for coating treatment were prepared for Examples 2 to 6 using dispersing resins 2 to 6, respectively. Stability,
The film forming properties are shown in Table 3.

(Comparative Examples 1 to 5) In the same manner as in Example 1 above, for each of Comparative Examples 1 to 5, dispersing resins 7 to 11 were used to prepare coating composition baths for coating treatment. The stability and film forming properties are shown in Table 4.

[0019]

By applying the dispersion resin of the present invention to an organic film-forming component, it is possible to obtain a self-deposition type coating composition which is excellent in forming a film on a metal surface and has good stability.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

Claims (2)

(57) [Claims] 1. A resin having a solid content of 5 to 550 g / l,
0.4-5.0 g / l of acid, 0.3-3.0 g of oxidizing agent
/ L, wherein the dispersed resin comprises (A) a carboxyl group-containing ethylenically unsaturated monomer; 2 to 10% by weight; (B) a polymer comprising 90 to 98% by weight of an ethylenically unsaturated monomer other than the above (A), wherein the nonionic surfactant is a monomer (solid content) of the above (A) and (B) A) a self-depositing coating composition comprising not more than 12% by weight based on the total amount of 2. The coating composition according to claim 1, wherein the acid is hydrofluoric acid and the oxidizing agent is hydrogen peroxide.