JPH0293077A - Production of black plated steel sheet - Google Patents

Abstract

PURPOSE:To form a black film having high blackness and superior adhesion by treating a Zn plated steel sheet in an aq. soln. contg. specified amts. of stannous chloride and an Ni or Co compd. CONSTITUTION:A Zn or Zn alloy plated steel sheet is immersed in an aq. soln. contg. 0.001-20wt.% water soluble stannous chloride and 0.01-50wt.% water soluble Ni compd. such as NiCl2 or Co compd. such as CoCl2 to blacken the surface of the steel sheet and the steel sheet is dried. A chromate film may be formed on the blackened surface while etching the surface as required. A soln. contg. one or more among colloidal silica, water glass, a silane coupling agent, org. resin, an aq. resin emulsion and chromic anhydride may be applied to the blackened surface and dried to form a protective coat. The chromate film and the protective coat may be successively formed.

Description

[Detailed description of the invention] Cliff deep” J Sae old ice condyle The present invention relates to a method for manufacturing a black-plated steel sheet.

Conventional ■ Ogitori Conventionally, the surface of galvanized steel sheets has been colored black in order to improve decorative properties, light absorption, heat absorption, light reflection prevention, etc.

As described above, conventional methods for applying black coloring to galvanized steel sheets include (a) applying black paint, (b) solution of chlorate, molybdate, chromic anhydride, sulfide, or copper sulfate. Methods such as (d) immersion in nitric acid solution, methods using TCI heating or electrolysis, and (d) immersion in nitric acid solution are known, but all of them have various problems. For example, method (a
According to 1, the coating cost is high, and the method (according to BL, it is not easy to manage the treatment liquid, and there are problems with waste liquid treatment.Furthermore, it is difficult to obtain a stable black film in a short time. In the case of method (C), equipment costs are generally high, and in particular, in the case of electrolysis, it is difficult to manage the electrolyte and control the electrolytic conditions. Although it can be blackened, pure galvanized steel sheets cannot be blackened.

The present inventors have developed a method for blackening the surface of galvanized steel sheets or zinc-based alloy coated steel sheets, as described above, in order to solve various problems. The purpose is to provide a new manufacturing method for galvanized steel sheets.
A further object of the present invention is to provide a method for producing a black plated steel sheet with excellent workability and corrosion resistance in which a protective film is formed after blackening.

The method for producing a black-plated steel sheet according to the present invention for eliminating the problem of "N" is to prepare a galvanized steel sheet or a zinc-based alloy-coated steel sheet by adding (a) 0.001 to 20% by weight of water-soluble stannous chloride and water-soluble FBL. The treatment is carried out in an aqueous solution containing 0.01 to 50% by weight of a nickel compound or a cobalt compound.

In the present invention, as the galvanized steel sheet, an electrolytic galvanized steel sheet or a hot-dip galvanized steel sheet is used, and as the zinc-based alloy plated steel sheet, a single-layer or multilayer galvanized steel sheet is used.

In the method of the present invention, such a galvanized steel sheet or a zinc-based alloy coated steel sheet (Al water-soluble stannous chloride 0°001~
20% by weight, and (b) an aqueous solution containing 0.01 to 50% by weight of a water-soluble nickel compound or cobalt compound (hereinafter referred to as
It is called a processing liquid. ) to achieve blackening.

In the above treatment solution, the concentration of water-soluble stannous chloride is
It ranges from 0.001 to 20% by weight. When the stannous chloride concentration is less than 0.001% by weight, it takes a long time, usually 3 minutes or more, to color the galvanized steel sheet, which not only lowers productivity but also prevents uniform coloring. Have difficulty. On the other hand, if it exceeds 20% by weight, the surface of the zinc-based alloy coated steel sheet will be colored and dissolved by immersion in the treatment solution for an extremely short time, usually 1 second or less, making it extremely difficult to control the coloring reaction. be.

Further, in the above treatment liquid, the concentration of the water-soluble nickel compound or cobalt compound is in the range of 0.01 to 50% by weight. When the concentration of the water-soluble nickel compound or cobalt compound is less than 0.01% by weight, galvanized steel sheets and zinc-based alloy coated steel sheets cannot be uniformly blackened, and in fact, they are colored gray. . On the other hand, when it exceeds 50% by weight, it is difficult to control the blackening reaction.

Examples of the water-soluble nickel compound or cobalt compound include, but are not limited to, chlorides, sulfates, nitrates, perchlorates, and sulfamates.

In the method of the present invention, the treatment liquid has a pl+ of 1.
It is preferably 7 or less. If the pH exceeds 7, the water-soluble tin salt will precipitate as tin hydroxide in the treatment solution, and the blackening reaction will not take place sufficiently.

In the method of the present invention, in order to treat a galvanized steel sheet or a zinc-based alloy coated steel sheet with such a treatment liquid, specifically, for example, the steel sheet may be spray-coated with the treatment liquid or immersed in the treatment liquid. . Thereafter, by drying the plated steel plate, a black plated steel plate with a blackened surface can be obtained.

According to the present invention, after blackening a galvanized steel sheet or a zinc-based alloy coated steel sheet as described above, the surface is further etched and a reactive chromate film is formed or applied. The type chromate coating can be formed in a single layer or in multiple layers. Methods for forming such reactive chromate films and paint-on chromate films are already well known. For example, a solution containing chromic acid, a silicic acid compound, and a trace amount of additives may be applied to the surface of the blackened steel sheet and dried to form a coated chromate film.

The coating amount is 0. It is preferable to select it within the range of O1 to Ig/i. Such a chromate protective coating increases corrosion resistance and prevents white rust from forming.

Furthermore, according to the present invention, after a galvanized steel sheet or a zinc-based alloy coated steel sheet is treated with a treatment liquid to blacken it as described above, the surface thereof is coated with silicate colloid, water glass,
A solution containing at least one selected from a silane coupling agent, an organic resin, an aqueous emulsion resin, and chromic anhydride is applied and dried to form a protective coating in a single layer or in multiple layers.

As the organic resin, thermosetting resins such as epoxy resins, acrylic resins, melamine resins, phenol resins, and urea resins are preferably used.

Further, as the aqueous emulsion resin, for example, emulsion resins such as acrylic-styrene resin, epoxy ester resin, acrylic resin, vinyl acetate resin, urethane resin, polystyrene, and ethylene-vinyl acetate copolymer resin are used. The coating amount of such a solution is such that the coating amount is 0.
．． It is preferable to select it within the range of 0.01 to 5 g/rrf.

According to the invention, all of the above-mentioned methods can also be combined. That is, after treating a galvanized steel sheet or a zinc-based alloy-plated steel sheet with a treatment liquid to blacken it as described above, a chromate film is formed in a single layer or in multiple layers, and then, as described above, On its surface, silicic acid colloid, water glass, silane coupling agent, organic resin,
A solution containing at least one selected from an aqueous emulsion resin and chromic anhydride is applied and dried to form a single or multilayer protective coating.

According to the method of the present invention, a galvanized steel sheet or a zinc alloy-plated steel sheet is blackened by treating it with an aqueous solution containing stannous chloride and a nickel compound or a cobalt compound at a predetermined concentration. It is possible to form a black film with high strength and excellent adhesion.

Further, according to the method of the present invention, after blackening the galvanized steel sheet or the zinc alloy-plated steel sheet as described above,
Chromate coating or silicate colloid on the surface,
A solution containing at least one selected from water glass, a silane coupling agent, an organic resin, an aqueous emulsion resin, and anhydrous chromic acid is applied and dried to form a protective film, or a combination of these films is applied. By forming this, it is possible to obtain a black-plated steel sheet that not only has excellent wear resistance and aesthetic appearance, but also is dense and has excellent workability and corrosion resistance. In particular, by forming a protective film in this way, the subtle color unevenness that occurs during the black coloring stage disappears, and a uniform surface color can be obtained, and the product thus obtained has a uniform appearance. I'll give it to you.

That is, by forming a transparent or semitransparent layer on the colored layer, the refractive index of light changes and the uniformity of the black surface improves.

Implementation (2) The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 As shown in Table 1, a galvanized steel sheet was immersed in a treatment solution of ρ111.5 containing stannous chloride and nickel chloride at a predetermined concentration for 5 to 60 seconds, dried, and the steel sheet was It turned black. The black galvanized steel sheet according to the present invention exhibits a dark brown to black color.

The degree of blackening of the black plated steel sheet obtained in this example is shown in Table 1 in terms of L value. The L value will be described later.

Examples 2 to 9 A galvanized steel sheet, a zinc-nickel alloy-plated steel sheet, a zinc-cobalt alloy-plated steel sheet, a hot-dip galvanized steel sheet, and an alloyed hot-dip galvanized steel sheet were immersed in the treatment solution shown in Table 2, dried, and It turned black.

The color tone and L(Ii!) are shown in Table 2.

Comparative Examples 1 and 2 Table 2 shows the results of treating electrogalvanized steel sheets using treatment solutions containing either stannous chloride or nickel chloride. When a treatment solution containing only stannous chloride was used, the surface was only colored gray, and moreover, the coating was easily peeled off. When a treatment solution containing only nickel chloride was used, no coloring occurred.

Example 10 Stannous chloride (0.5% by weight) and nickel chloride (10% by weight)
An electrogalvanized (20 g/I) steel plate was immersed in a treatment solution (pH 1.5) containing (% by weight) for 30 seconds, dried, and blackened.

Next, a coated chromate solution (a solution containing anhydrous chromic acid, colloidal silica, and phosphoric acid) is applied to the blackened galvanized steel sheet so that the amount of chromium deposited is 100 μ/d, and dried to remove the chromate. The coating was formed into a single layer.

Example II Stannous chloride (0.5% by weight) and nickel chloride (10% by weight)
An electrogalvanized (20 g/m) steel plate was soaked in a treatment solution (ρ) l 1.5 ) containing % by weight for 30 seconds, dried, and blackened.

Next, a silane coupling agent was applied to this blackened galvanized steel sheet, followed by roll squeezing and drying to give a coating thickness of 1 g/rd.

Example 12 A solution in which silicic acid colloid and water glass No. 3 were mixed at a weight ratio of 8/2 was applied onto the blackened galvanized plate obtained in Example 11 and dried to give a coated amount of 2 g. /m.

Example 13 A solution of chromic anhydride and aqueous acrylic resin emulsion mixed at a weight ratio of 1/10 was applied onto the blackened galvanized steel sheet obtained in Example 11 and dried to give a coating weight of 3 g.
/ m.

Example I4 A water-based acrylic resin emulsion was applied onto the blackened galvanized steel sheet obtained in Example 11, dried, and the coating weight was 3.
g/ni.

Example 15 A solution containing a water-based acrylic resin emulsion, colloidal silica, and silane coupling agent mixed at a weight ratio of 12/20/1 was applied onto the blackened galvanized steel sheet obtained in Example 11, rolled, and dried. did.

Example 16 An aqueous epoxy resin emulsion was applied onto the blackened galvanized steel sheet obtained in Example 11, dried, and the coating weight was 3.
g/rrf.

Example 17 A coated chromate solution (containing chromic anhydride, colloidal silica, and phosphoric acid) was applied as a first layer onto the blackened galvanized steel sheet obtained in Example 11, so that the amount of chromium deposited was 1.
00 g/m and dried. Next, as a second layer, a solution of silicic acid colloid and water glass No. 3 mixed at a weight ratio of 8/2 was applied onto the steel plate, dried, and
The amount of film deposited was 2 g/m.

Example 18 A coated chromate solution (Cosmer C manufactured by Kansai Paint Co., Ltd.) was applied as a first layer onto the blackened galvanized steel sheet obtained in Example 1■ so that the amount of chromium deposited was 100■/M. , dried. Next, as a second layer, an epoxy-modified water-based acrylic resin emulsion was applied on the steel plate at a rate of 1 to 2 g/m.
It was applied at a ratio of and dried.

Comparative Example 3 A protective film was not formed on the blackened galvanized steel sheet obtained in Example 11, and the steel sheet was used as it was for this comparative example.

Regarding the blackened steel sheets of Examples 10 to 18 and Comparative Example 3, the blackness before processing, uniformity of appearance, corrosion resistance, and blackness after processing are shown in Table 3. Furthermore, the degree of blackness before processing is
Blackness refers to the degree of blackness before performing a 90° bending test.
The L value was measured using a color difference meter (manufactured by Suga Test Instruments Co., Ltd.). The smaller the L value, the higher the degree of blackness.

Further, the uniformity of appearance was visually observed. Corrosion resistance is
Based on the salt spray test (JIS 2371), the test was carried out using 5% salt water, and the time until white rust appeared was measured.

The blackness after processing refers to the change in blackness when a 90' bending test is performed on the steel sheets obtained in each example, and is the result of visual observation.

The above results are shown in Table 3. It is clear that the steel sheet according to the example has excellent blackness after processing, uniformity of appearance, and corrosion resistance.

In particular, the steel plates according to Examples 12 to 18 have excellent uniformity in appearance.

Claims (4)

[Claims] (1) Galvanized steel sheet or zinc-based alloy coated steel sheet (a
) 0.001-20% by weight of water-soluble stannous chloride;
b) Water-soluble nickel compound or cobalt compound 0.01
1. A method for producing a black plated steel sheet, comprising processing in an aqueous solution containing ~50% by weight. (2) Galvanized steel sheet or zinc-based alloy coated steel sheet (a
) 0.001-20% by weight of water-soluble stannous chloride;
b) Water-soluble nickel compound or cobalt compound 0.01
A method for producing a black-plated steel sheet, which comprises treating the surface in an aqueous solution containing ~50% by weight to blacken the surface, and then forming a chromate film. (3) Galvanized steel sheet or zinc-based alloy coated steel sheet (a
) 0.001-20% by weight of water-soluble stannous chloride;
b) Water-soluble nickel compound or cobalt compound 0.01
After treatment in an aqueous solution containing ~50% by weight to blacken the surface, at least one selected from silicic acid colloid, water glass, silane coupling agent, organic resin, aqueous emulsion resin, and chromic anhydride is applied to the surface. 1. A method for producing a black-plated steel sheet, which comprises applying a solution containing one of the above components and drying the solution to form a protective film. (4) Galvanized steel sheet or zinc-based alloy coated steel sheet (a
) 0.001-20% by weight of water-soluble stannous chloride;
b) Water-soluble nickel compound or cobalt compound 0.01
After processing in an aqueous solution containing ~50% by weight to blacken the surface, a chromate film is formed, and then silicic acid colloid, water glass, silane coupling agent, organic resin, and aqueous emulsion resin are applied to the surface. and applying a solution containing at least one selected from chromic anhydride,
A method for producing a black plated steel sheet, which comprises drying to form a protective film.