JPS63109176A - Chemical conversion treatment of copper-base metal - Google Patents

Abstract

PURPOSE:To form a dense uniform film on the surface of a copper-base metal by chemical conversion treatment with a soln. contg. phosphate ions, metal ions, halogen ions and an oxidizing agent by previously sticking colloidal particles to the surface of the metal. CONSTITUTION:A soln. of 0.5-3.5pH for chemical conversion treatment contg. phosphate ions, metal ions which are present in the aq. soln. as a stable dihydrogenphosphate compd. in combination with the phosphate ions and undergo reduction in solubility by a dehydrogenation reaction, e.g. Zn or Mn ions, ions of halogen other than fluorine and an oxidizing agent which accelerates the dissolution of copper in the acidic soln. is prepd. When the soln. having >=400mV oxidation-reduction potential is brought into contact with the surface of a copper-base metal to form a film by chemical conversion treatment, a soln. contg. dispersed colloidal particles of an inorg. compd. such as a Ti compd. is previously brought into contact with the surface of the metal to stick the colloidal particles to the surface. Thus, a dense uniform film is formed by chemical conversion treatment by about 0.5-5g/m<2> and the adhesion of the film to copper is improved.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention involves bringing a phosphate solution into contact with a metal surface to form a film of an insoluble compound mainly composed of phosphate on the metal surface. It relates to compound treatment on surfaces to prevent corrosion of metals, improve lubricity of metal surfaces, and improve adhesion of paint films. More specifically, the present invention relates to a method for chemical conversion treatment of copper-based metals, which forms a thin and uniform chemical conversion film on the surface of copper-based metals.

[Conventional technology]

Chemical conversion treatment of metals has traditionally been studied mainly for steel, and phosphate treatment and chromate treatment have been widely used for the purposes of rust prevention, improved adhesion, and imparting lubricity, and have become industrially important technologies. There is.

On the other hand, copper is an industrially useful metal material, but since it is a metal that is stable against acids, it is difficult to conduct a chemical conversion treatment in which a film-forming reaction progresses by dissolving it in an acid in an industrially stable manner. Development has lagged behind chemical conversion treatment for steel. However, the method of forming a phosphoric acid film on the surface of a copper-based metal is expected to be widely implemented industrially in the future. In particular, copper-based metals are immersed in a chemical conversion treatment bath that contains oxidizing agents such as phosphate ions, zinc ions, and hydrogen peroxide, and halogen ions other than fluorine to create a stable coating on the copper surface. It was announced that a chemical conversion film could be formed (Japanese Patent Laid-Open No. 61-2
No. 6783), chemical conversion treatment is expected to become more widespread in the future for copper-based metal parts such as electric wires and cables.

[Problem that the invention seeks to solve]

The present invention relates to improving the adhesion between a coating film and copper, which is one of the effects of chemical conversion coating treatment on a copper surface.

When using chemical conversion coatings as a means of improving paint film adhesion,
The structure of the chemical conversion film is fine, and it is desirable that the film thickness be thinner to a certain extent.For example, as the amount of the chemical conversion film adheres increases, parts of the chemical conversion film may become thinner before the film peels off due to external forces acting on the film. Destruction occurs, resulting in a decrease in the adhesion between the coating film and the copper.

For example, when the present inventors further studied the method disclosed in JP-A No. 61-26783, it was found that the adhesion of the coating film tended to deteriorate when the coating weight was 10 kg or more. Furthermore, if the structure of the chemical conversion film is rough, the thickness of the coating film applied thereon will be uneven, which will easily cause cracks in the coating film. Generally, when the amount of chemical conversion film deposited on the copper surface decreases, it becomes difficult to form a uniform and fine chemical conversion film. In other words, when trying to create a thin chemical conversion film, there may be some areas on the copper surface where there is no chemical conversion film, or the crystals will be uneven in size and not fine, resulting in insufficient adhesion to the paint film. Become.

The present inventors have arrived at the present invention as a result of extensive research into a chemical conversion treatment method that can produce uniform and fine crystals of a chemical conversion film even if the amount of deposition on the copper surface is small.

[Means for solving problems]

The present invention relates to phosphate ions, metal ions that exist as stable dihydrogen phosphate compounds in aqueous solutions and whose solubility decreases due to dehydrogenation reactions, halogen ions other than fluorine, and halogen ions that exist in acidic solutions. Before bringing a chemical conversion treatment solution containing an oxidizing agent that promotes dissolution of copper into contact with the surface of the copper-based metal to form a chemical conversion film on the surface, colloidal particles of an inorganic compound are attached to the surface of the copper-based metal in advance. This is a method for chemical conversion treatment of copper-based metals.

[Embodiments of the invention]

Colloidal particles used in the present invention (particle size 10 to 100
00 people) adheres to copper-based metal surfaces and creates fine chemical coatings.
It is a component that makes the coating uniform and improves the adhesion with the coating film, and may be of any kind, but titanium-based colloid particles are particularly preferred because they are easily available industrially. In addition to titanium-based materials, for example, S102. P bo,
S t C, S i3N4.

Examples include BN and silicic anhydride. There is no particular method for attaching colloidal particles to the surface of a copper-based metal, but it is easy to bring the copper-based metal into contact with a solution in which colloidal particles are dispersed, and it is easy to obtain a uniform product. preferable.

On the surface of copper-based metals that come into contact with a chemical conversion treatment solution containing phosphate ions, metal ions, and an oxidizing agent that promotes the dissolution of copper in acidic solutions, copper dissolution and precipitation of cuprous halides and phosphates occur. An anodic reaction based on the action of the oxidizing agent and a cathodic reaction based on the action of the oxidizing agent proceed, resulting in the formation of a chemical conversion film.

Although the influence of colloidal particles on the process of forming a chemical conversion film is not clear, the colloidal particles are adsorbed to the surface of the copper-based metal, and a potential difference is created between the colloidal particles and the surface of the copper-based metal to which no colloidal particles are attached. The oxidizing agent is likely to come into contact with the copper-based metal surface (therefore, it is assumed that the reaction to form a chemical conversion film is likely to occur).

The oxidizing agent that promotes dissolution of copper in the chemical conversion treatment solution of the present invention is
For example, hydrogen peroxide or nitrite ions. Also,
In the treatment solution of the present invention, zinc, manganese, iron, calcium, magnesium, etc. are used as phosphate ions and metal ions that exist as stable dihydrogen phosphate compounds in aqueous solutions and whose solubility decreases due to dehydrogenation reactions. can do.

Regarding the composition of the chemical conversion treatment liquid, the chemical conversion film forming reaction can be stabilized by adding chlorine ions, bromide ions, iodine, or a mixture of two or more of these ions to the liquid. An example of a preferable liquid composition for smoothly forming a chemical conversion film is one in which the chemical conversion treatment liquid IL contains 2 g of phosphate ions, 2 g of zinc ions, and 1 g or more of halogen ions excluding fluorine.

In the present invention, the copper dissolution promoting effect of the oxidizing agent can be adjusted to be preferable for stable formation of a chemical conversion film by setting the oxidation-reduction potential (A g Cl electrode potential) of the chemical conversion treatment solution.

In the conventional technique of JP-A No. 61-26783, in order to obtain a uniform chemical conversion film, the amount of chemical conversion film deposited must be 5 to 10 g/
However, in the present invention, a denser and more uniform coating can be obtained with a coating coverage of 0.5 to 5 g/g. Further, in this prior art, the chemical conversion coating was amorphous or in an undeveloped state of crystals, but in the present invention, it was confirmed by electron microscopy that it was crystalline or amorphous-crystalline.

In the present invention, the chemical conversion treatment liquid can be applied to the copper-based metal surface by a commonly used method such as a dipping method or a spray method.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Example 1> A chemical conversion solution was prepared in which the concentrations were adjusted to 32.5 g/L of zinc ions, 30 g/L of chloride ions, 10 g/L of phosphate ions, and 10 g/L of hydrogen peroxide. On the other hand, a mild steel rectangular wire of 2 dragons x 5 fins, which had been previously degreased with acetone, was immersed for about 20 seconds in an aqueous solution in which Percolene Z (manufactured by Nippon Parkerizing Co., Ltd.), a titanium-based colloid, was dissolved at 3 g/L. This immersion causes titanium-based colloid particles to adhere to the surface.

The above-mentioned mild steel rectangular wire was immersed in the above-mentioned treatment liquid for 3 minutes without drying. Note that this treatment liquid is in a stirring state. Further, the chemical conversion treatment liquid has a temperature of 20° C., a pH of 1.7, and an oxidation-reduction potential of 550 mV (Ag (1! electrode)).

FIG. 1 shows a 400x photograph of the surface of the chemical conversion coating thus obtained, which was observed using a scanning electron microscope.

Next, the chemically treated mild steel rectangular wire was immersed in 1N hydrochloric acid.
The chemical conversion coating was immersed for a period of time to dissolve it, and the change in weight before and after the immersion was examined. Table 1 shows the amount of the chemical conversion coating attached.

Comparative Example 1> A chemical conversion treatment was performed using the same chemical conversion treatment solution as in Example 1 except that the immersion step of Percolene Z in Example 1 was omitted. 40 of the chemical conversion coating produced by this comparison 1.
A 0x micrograph is shown in FIG. 2, and the amount of adhesion is shown in Table 1.

Next, an ester imide varnish (Isomit R1, manufactured by Schenectady Co., Ltd.) was applied to the chemical conversion treated rectangular wire obtained in Comparative Example 1 and Example 1, and to the non-chemically treated rectangular wire to a film thickness of 5 to 10 mm.
It was applied to a thickness of μm and baked at 200° C. for 2 hours.

Next, the adhesion of the rectangular wire coated with esterimide was evaluated using the following two methods, and Table 1 shows the results.

(Method 1)...Five 2fi square cuts were made in the esterimide coated on a flat wire, and adhesive tape was adhered thereon. When the adhesive tape was peeled off, the number of notched esterimide coatings that peeled off from the flat wire was determined.

(Method 2) A rectangular wire coated with esterimide was stretched until it was cut, and the adhesion state of the esterimide coating was examined.

-1hi J 几 Shita' 1LQ Kasa 1■Kushigu'Ku 1 坙Note) Adhesion evaluation standard O: The coating film does not peel off.

×: Peeling of the coating film is observed.

As shown in Table 1, Example 1 compared to Comparative Example 1.
The amount of chemical conversion film attached is smaller.

Looking at the electron micrograph in Figure 2, Comparative Example 1 shows that there are some areas where there is no chemical conversion coating, and the crystal size is 5.
It is large at ~10 μm. On the other hand, in the case where the chemical conversion treatment bath of Example 1 shown in FIG. 1 was used, there was no part without a chemical conversion film, and the crystal size was fine and uniform, ranging from 1 to 3 μm. Therefore, it is clear that even though the amount of chemical conversion film deposited in Example 1 is smaller than that in Comparative Example 1, the chemical conversion film is fine and uniform. As shown in Table 1, the chemical conversion coating of Example 1 had better adhesion than the chemical conversion treatment bath of Comparative Example 1. This is thought to be due to the growth of coating crystals.

〔Effect of the invention〕

As shown above, according to the chemical conversion treatment method of the present invention,
Even if the amount of chemical conversion film deposited is small, a fine and uniform chemical conversion film can be formed on copper-based materials, and its industrial value is great.

[Brief explanation of the drawing]

FIG. 1 is a photograph taken with a scanning electron microscope of a chemical conversion coating produced according to an embodiment of the present invention, showing particles constituting the coating, and FIG. 2 is a photograph showing the same particles constituting the coating as in FIG. 1 for a conventional example.

Claims (1)

[Scope of Claims] (1) A phosphate ion, a metal ion that exists as a stable dihydrogen phosphate compound in an aqueous solution with the phosphate ion and whose solubility decreases due to a dehydrogenation reaction, a halogen ion excluding fluorine, and Before bringing a chemical conversion treatment solution containing an oxidizing agent that promotes dissolution of copper into contact with the copper-based metal surface to form a chemical conversion film on the surface, a colloid of an inorganic compound is applied to the copper-based metal surface in advance. A chemical conversion treatment method for copper-based metals characterized by attaching particles. (2) The chemical conversion treatment method according to claim 1, characterized in that the copper-based metal is brought into contact with a solution in which the colloidal particles are dispersed, so that the colloidal particles are attached to the surface of the copper-based metal. (3) The chemical conversion treatment method according to claim 1 or 2, wherein the colloidal particles are titanium-based colloidal particles. (4) the pH of the chemical conversion treatment liquid is 0.5 to 3.5;
The chemical conversion treatment method according to any one of claims 1 to 3, wherein the redox potential (AgCl electrode) is 400 mV or more.