JP3139795B2 - Metal surface treatment agent for composite film formation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel surface treating agent which forms a composite film which is excellent in corrosion resistance on the surface of a metal such as iron, zinc, aluminum and the like and which is excellent as a coating base.

[0002]

2. Description of the Related Art At present, painted articles such as automobile bodies and building materials are required to have higher corrosion resistance than ever. Conventionally, phosphate treatment, chromate treatment, and the like have been performed as metal surface treatments, but conventional metal surface treatment agents do not always sufficiently satisfy high corrosion resistance and coating film adhesion.

In general, when an organic film such as a paint or an adhesive is applied to a metal surface such as iron, zinc, and aluminum, a method for forming a phosphate film on the metal surface as a pretreatment is known. If a phosphate film is formed on a metal surface and then an organic film typified by a paint is applied, corrosion resistance and coating film adhesion are improved. In the case where corrosion resistance is further required, it is applied after post-treatment such as chromic acid sealing after phosphate treatment or after applying a primer paint. However, the effect of post-treatments such as chloric acid sealing is small, and the application of a primer paint improves the coating performance, but the workability is remarkably deteriorated due to an increase in the number of coating steps.

At present, primers are indispensable for painted objects such as automobile bodies and building materials. In the case of an automobile body, after a zinc phosphate film is formed on a metal surface, it is immersed in a water-based paint to perform electrodeposition coating. This coating is a kind of primer coating, and its object is to improve the corrosion resistance of the painted surface and to secure the corrosion resistance of the inner surface of an automobile body, etc., which is difficult to apply a top coat. The same applies to building materials, in which a primer coating is applied before a top coating for the purpose of improving corrosion resistance.

[0005] Although there is a demand for shortening the process for the purpose of improving workability and reducing costs in the painting process, no technology has yet been developed to meet the purpose. That is, the phosphate film alone has poor corrosion resistance, and the coating alone does not satisfy the requirements in terms of corrosion resistance and coating adhesion. Similarly, where high corrosion resistance is required, a phosphate coating and further primer coating are essential. For this reason, there is a problem that the coating cost is high and the work area is large, and a metal surface treatment agent having high corrosion resistance and coating adhesion is required, and a surface treatment agent that can omit primer coating is also required. I have.

[0006]

As a means for solving the above-mentioned problems, the present invention provides a metal (hereinafter referred to as a metal) which can be treated with a phosphate film, such as iron, zinc, and aluminum, having a high level of corrosion resistance and coating adhesion. A metal surface treatment agent capable of imparting
It is an object of the present invention to provide a metal surface treating agent which can maintain the current corrosion resistance level and can omit the primer coating.

[0007]

As a result of repeated studies to solve the above problems, when a film is formed with a phosphating solution containing an organic polymer compound having specific properties or a salt thereof, The present inventors have found that high corrosion resistance and high paint adhesion can be obtained and completed the present invention.

In other words, it is characterized by comprising a phosphate surface treatment solution containing a cationic organic polymer compound having at least one cationic nitrogen atom and having a molecular weight of 1,000 to 1,000,000 or a salt thereof. By treating a metal surface with a metal surface treating agent for forming a composite film, a composite film having the above-described excellent performance can be formed. Incidentally, the composite coating in the present invention, a resin of a cationic organic compound or a salt thereof penetrates into the crystal grain of the phosphate and the grain boundary of the crystal,
This is a film in which phosphate crystals and a resin form a composite.

The surface treating agent of the present invention is a solution obtained by dissolving or stably dispersing a cationic organic polymer compound or a salt thereof in a phosphating solution. Phosphating solutions are iron, zinc,
A surface treatment solution capable of simultaneously forming a phosphate film on a metal surface such as aluminum or two or more of these metals, and usually zinc ions and phosphate ions are essential components. Metal ions such as ions, nickel ions, manganese ions, and calcium ions, fluorides, and various oxidizing agents are added. However, the present invention is not particularly limited, and any known phosphating solution may be used.

[0010] The cationic organic high molecular compound includes at least one cationic nitrogen atom and has a molecular weight of 1,000 to 10.
It is of 00000, or epoxy resins, polybutadiene resins, acrylic resins, maleic resins anhydride
Having one or more resin skeletons selected from the group consisting of
Is a high molecular compound .

The cationic organic high-molecular compound salt is a salt of the above-described cationic organic high-molecular compound with an inorganic acid salt such as phosphate, nitrate or sulfate, or an organic acid such as acetate, propionate or glyconate. Acid salt. These cationic organic polymer compounds or salts thereof may be used alone or in combination of two or more. If the molecular weight is less than 1,000, the effect of improving corrosion resistance is poor, and if it is more than 1,000,000, dissolution or stable dispersion in a zinc phosphate bath becomes difficult.

Further, the present invention does not refuse the addition of paint additives such as pigments, other types of resins, activators, and the like as necessary. As the metal surface treatment method of the present invention, any method of chemical conversion treatment and electrolytic treatment by spraying or dipping is possible,
The treatment method of the treating agent of the present invention is not limited.

[0013]

As is well known, the phosphate film is formed by the leaching of the metal to be treated, thereby increasing the pH of the phosphating solution at the metal interface. In addition, since the cationic organic polymer compound is cationic and is dissolved or dispersed in water, an increase in pH lowers the solubility or dispersibility of the cationic organic polymer compound and promotes the separation. Therefore, when the metal is treated with the surface treatment agent of the present invention, the phosphate and the organic polymer compound are simultaneously precipitated to form a composite film.

The phosphate film is porous and the contribution of corrosion resistance to the film alone is relatively small. The composite film formed by the surface treatment agent of the present invention has good corrosion resistance because the organic polymer compound covers the porous property of the phosphate film. Further, the film formed with the surface treatment agent of the present invention,
Since the zinc phosphate film is protected by the organic polymer, for example, it is possible to prevent the phenomenon that the phosphate film partially dissolves in the paint at the time of coating and deteriorates the adhesion of the paint, or the next coating after the phosphate film processing step. Has the effect of preventing the generation of rust in the intermediate process up to the process

The present invention is characterized in that a phosphating solution containing a cationic organic polymer compound or a salt thereof is used. For example, after treating the metal surface with a phosphating solution, treatment with a solution containing a cationic organic polymer compound or a salt thereof has no effect. This is because the composite coating is not formed and the resin coating merely covers the phosphated coating, and the coating is easily peeled off and is not strong. Also,
The fact that the composite coating of the present invention retains a high level of corrosion resistance and coating adhesion is confirmed by a more severe test method than the conventional one shown in Examples.

If an anionic organic high molecular compound or a nonionic organic high molecular compound is used instead of the cationic organic high molecular compound, it is difficult to form a film by bending out due to an increase in pH.

[0017]

The following examples illustrate the effects of the present invention in detail. However, the present invention is not limited to these examples, and is an example of a normal phosphate coating pretreatment and a normal coating system. It is shown as.

(Test plate) Cold rolled steel plate Electroplated steel plate (zinc basis weight 20 g / m ² ) Aluminum plate (JIS-5052)

(Test Surface Treatment Agent) The cationic organic polymer compounds used in the examples and the polymer compounds used in the comparative examples are shown in Table 1. As a typical phosphate surface treatment liquid excluding the organic polymer compound, a phosphate surface treatment liquid composed of an automotive surface treatment agent of Palbond L3020 (manufactured by Nippon Parkerizing Co., Ltd.) was used.

(Treatment method) 1) Degreasing Fine cleaner L4460 (manufactured by Nippon Parkerizing Co., Ltd.) 2% solution sprayed at 42 ° C. for 120 seconds 2) Rinse with water at room temperature for 30 seconds Spray 3) Surface adjustment 1
% Liquid, normal temperature, 20 seconds Spray The pretreatments of Examples 1 and 3) were performed for both Examples and Comparative Examples. 4) Surface Treatment of the Present Invention Both the surface treatment agent of the present invention and the surface treatment agent of the comparative example were treated under the following conditions. 42 ° C. 120 seconds immersion 5) Water washing Room temperature 30 seconds spray 6) Deionized water washing (conductivity; 0.2 μs / cm) Room temperature 20 seconds Spray Both Examples and Comparative Examples were performed in the same manner.

(Coating) Both the examples and comparative examples were coated in the following steps. 1) Primer coating Electrodeposition coating (Electron 9410; manufactured by Kansai Paint Co., Ltd.) Film thickness 20 μm, baking 175 ° C., 30 minutes 2) Intermediate coating KPX36 (Kansai Paint Co., Ltd.) Film thickness 30 μm, baking 140 ° C., 30 minutes 3) Top coating Luga Bake B531 (Manufactured by Kansai Paint Co., Ltd.) Thickness 40μm Baking 140 ℃ 30 minutes

(Performance evaluation) 1) Water-resistant secondary adhesion After the coated plate was immersed in deionized water at 40 ° C. for 240 hours, a 2 mm square gobang was cut with a sharp cutter to reach the substrate.
The pieces were cut into 00 pieces, and the number of strips after the cellophane stripping was evaluated. The smaller the number of peeled pieces, the better. 2) was cross scratch to reaching the substrate with a sharp cutter in a combined cycle test coated plate, the following cycle T ₁ → T ₂ repeated 14 cycles, one side maximum coating blister width from the cross scratch after test Measured and evaluated. T ₁ : Salt spray test (JIS-Z2371): 24 hours T ₂ : Wet test (50 ° C., 70% RH): 216 hours

[0023]

[Table 1]

(Examples) Table 2 shows the results of evaluation using cold-rolled steel sheets. Table 3 shows the results of evaluation using the electrogalvanized steel sheet.

(Comparative Example) Examples in which an organic polymer compound other than the product of the present invention was used or in which no cationic organic polymer was used were treated and evaluated in the same manner as in the examples.

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

[0029]

The effects of the present invention are shown in Tables 2, 3, and 4, respectively, which show the coating film adhesion and the corrosion resistance of the cold-rolled steel sheet, the electrogalvanized steel sheet, and the ammonium sheet subjected to the surface treatment together with the comparative examples. It can be seen that those treated with the metal surface treating agent for forming a composite film of the present invention have significantly improved corrosion resistance and coating film adhesion as compared with the phosphate treatment. Further, even when the primer coating is omitted, the present invention shows performance similar to that obtained by coating the phosphate film with the primer. It can be seen that when an organic polymer compound not included in the present invention is used, there is no effect or the performance deteriorates. As described above, the metal surface treating agent for forming a composite film according to the present invention improves corrosion resistance and coating film adhesion, and further enables elimination of primer coating.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-177379 (JP, A) JP-A-1-177381 (JP, A) JP-A-58-177473 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C23C 22/00-22/86 C09D 5/00 C09D 5/08 C09D 133/06 C09D 163/00

Claims (1)

(57) [Claims] An epoxy resin containing at least one cationic nitrogen atom and having a molecular weight of 1,000 to 1,000,000 .
Polybutadiene resin, acrylic resin and anhydrous maleic
One or more trees selected from the group consisting of activated resins
A metal surface treatment agent for forming a composite film, comprising a phosphate surface treatment solution containing a cationic organic polymer compound having a fatty skeleton or a salt thereof.