JPS62280376A - Production of highly blackened surface-treated steel by alternating electrolysis - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a processing soln. and to improve the workability, corrosion resistance, and blackening degree of treated steel by treating steel plated with a Zn-Ni alloy having a specified composition in specified thickness in a soln. contg. a nitric ion under specified conditions by alternating electrolysis. CONSTITUTION:The steel plated with a Zn-Ni alloy contg. 5-20% Ni at the rate of 10-40g/m<2> is treated in the processing soln. contg. a nitric ion. The steel is alternately kept at an anode and a cathode, and the ratio of the time of anodic treatment to the time of cathodic treatment is controlled to 0.1-1. The alternating cycle is controlled to 1-50Hz, the total treating time is adjusted to 1-30sec, the current density in the anodic electrolysis of the alloy-plated steel is regulated to 5-100A/dm<2>, the current density ratio of anode to cathode is adjusted to 1/0.1-1, and electrolysis is applied. The steel is then treated with a CrO3 chromating soln. to deposit a chromate film at the rate of 5-100mg/m<2>, expressed in terms of Cr, and/or a water-dispersible or water-soluble resin or a silica sol can be coated at the rate of 0.3-3g/m<2>, based on dry weight.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing surface-treated steel materials, and particularly to a method for manufacturing surface-treated steel materials with a high degree of blackening by alternating electrolysis.

<Prior art and its problems> Home appliances, copying machines, information communication devices, automatic devices (1) Materials widely used for interiors, interior building materials, etc.
After that, blackening treatment is applied by painting or chromate treatment, etc.
It is a product. However, in recent years, there has been an increasing demand for steel manufacturers to supply blackened surface-treated steel sheets for the purpose of omitting processes and reducing costs.

The performance required for blackened surface-treated steel sheets includes smoothness, weldability, corrosion resistance, and blackness. processing time) ■Does not require major modification of the existing plating line ■Does not cause deterioration of the processing solution ■Able to achieve uniform processing ■Good black color tone ■Good corrosion resistance ■Weldability Good things ■Additional things Good things [Phase] The film is hard to get scratched, etc.

Conventional blackening treatment methods include (i) black painting method;
i) Black chromate method, (iii) Chemical treatment method ((a)
JP-A-50-55546, (b) JP-A-52-762
No. 37, (c) JP-A-52-76238, (d) JP-A-60-121275, (c) JP-A-60-1812
No. 77) liV) Heat treatment method (JP-A-55-91993
IV) Anodic electrolytic treatment method (JP-A-58-151490, JP-A-58-151491)
No.), (Vi) Cathode electrolytic treatment method (Japanese Unexamined Patent Publication No. 1-190
No. 588).

However, (1) the black painting method requires painting equipment;
：'：Requires expensive capital investment, which increases manufacturing costs.

(ii): The '41 color chromate method requires a long reaction time and cannot be processed in an electroplating line. Furthermore, since the drug uses silver salt, it has a high (it+) value.

(ii) Chemical treatment methods (a) to (C) are types of displacement plating that use steel ions. 1.1. Uniform in high-speed line production because Zn etc. are dissolved in the liquid. j
I can only do color processing. In addition, the blackening layer cannot obtain sufficient film strength. (d) and (c) are oxidation reactions carried out in an aqueous chain acid solution, and basically, (,]) ~
It is the same as (C), and Zn, Ni, etc. dissolve in the processing solution, and the processing solution deteriorates in a short period of time. Moreover, the formed blackening layer also has the following properties: 1. Only low chromaticity and bluish tones
i? I can't do it.

(iv) The heat treatment method requires expensive equipment, and it is difficult to control uniform heating, and it is difficult to control coloration.

(V) The anodic electrolytic treatment method is described in JP-A-58-151491 and JP-A-58-151490 as having the advantage that blackening can be controlled by an electric group. However, the plated metal dissolves in the electrolytic solution, causing liquefaction, and the plated metal must be dissolved again, which is economically disadvantageous.

(vi) The cathodic electrolytic treatment method is an excellent treatment method in that it eliminates the dissolution of the plating layer, which is the drawback of (V), but the blackness cannot be obtained unless the blackening layer is relatively thick. The disadvantage is that the thicker the layer, the worse the strength and adhesion.

<Problems to be Solved by the Invention> As mentioned above, the drawback of the prior art is that the treatment with a strong black layer causes severe deterioration of the treatment solution, making it difficult to manufacture on an actual line. On the other hand, although the technique of forming a black layer by cathodic treatment causes little deterioration of the treatment solution, it has the disadvantage that the formed black layer has uneven adhesion strength and peels off when bent.

Therefore, in order to establish a processing method that has excellent adhesion and processability and provides a stable black color without deterioration of the processing solution, the present inventors have conducted a detailed study of the prior art described in 1) 1. (
We have discovered a method for surface treatment with a high degree of blackening using alternating electrolytic treatment, which eliminates the drawbacks of V) anodic electrolytic treatment and (vi) cathodic electrolytic treatment and obtains only the advantages of each.

According to this alternating electrolytic treatment method, since anodic electrolytic treatment and cathodic electrolytic treatment are performed alternately, dissolution of metal into the electrolytic solution is reduced, and deterioration of the electrolytic solution is significantly suppressed.

<Objective of the Invention> The object of the present invention is to provide a surface-treated steel material with a high degree of blackening by an alternating electrolytic method, which has little deterioration of the treatment solution, has stable high blackness, and has excellent workability, weldability, and corrosion resistance. The purpose is to provide a manufacturing method.

<Structure of the Invention> According to the first aspect of the present invention, the steel material contains 5 to 20% Ni. After applying n-Ni alloy plating at 10 to 40 g/m2, the time for holding the Zn-Ni alloy plated material on the anode and cathode in a treatment solution containing nitrate ions is calculated based on the anode treatment time 1. The processing time ratio is in the range of 0.1 to 1,
and the alternating period is 1 to 50 Ilz, the total treatment time ratio is 0 seconds, the anodic electrolytic current density of the Zn-Ni alloy plating material is 5 to 100 A/dm', and the ratio of the anode current density to the cathode current density. Provided is a method for producing a surface-treated steel material with a high degree of blackening by an alternating electrolytic method, which is characterized in that the electrolytic treatment is performed at a ratio of 1:0.1 to 1:0.1 to 1:1.

According to the second aspect of the present invention, after applying a Zn-Ni alloy plating containing 5 to 20% Ni to a steel material by lO to 40 g/rr+2, the Zn-Ni alloy plating material is treated with a treatment solution containing nitrate ions. In the process, the holding time at the anode and the cathode is set to a ratio of 0.1 to 1 for the cathode treatment time to an anode treatment time of 1, and the alternating period is set to 1 to 50 Hz, and the total treatment time ratio is 0 seconds. The anodic electrolytic current density of the Zn-Ni alloy plated material is 5 to 100 A/dm2, and the ratio of anode current density to cathode current density is 1:0. After electrolytic treatment as l-1, chromate treatment is performed with a chromate solution containing chromic anhydride as the main component, and the chromate film is converted to C
Provided is a method for producing a surface-treated steel material with a high degree of blackening by an alternating electrolytic method characterized by depositing 100 mg/m2.

According to the third aspect of the present invention, after plating a steel material with a Zn-Ni alloy containing 5 to 20% Ni at 10 to 40 g/lT11, the Zn-Ni alloy plated material is treated with a treatment solution containing nitrate ions. In the process, the holding time at the anode and the cathode is set to a ratio of 0.1 to 1 for the cathode treatment time to an anode treatment time of 1, and the alternating period is set to 1 to 50 Hz, and the total treatment time ratio is 0 seconds. After electrolytically treating the Zn-Ni alloy plated material with an anodic electrolytic current density of 5 to 100 A/dm'' and a ratio of anode current density to cathode current density of 1:0.1 to 1, water dispersion is performed. Provided is a method for producing a surface-treated steel material with a high degree of blackening by an alternating electrolysis method, which is characterized in that a water-soluble or water-soluble resin or silicic acid sol is applied in a dry pile at a rate of 0.3 to 3 g/rrf.

According to the fourth aspect of the present invention, the steel material contains 5 to 20% Ni. After applying n-Ni alloy plating at 10 to 40 g/m2, the time for holding the Zn-Ni alloy plated material on the anode and cathode in a treatment solution containing nitrate ions is calculated based on the anode treatment time 1. The processing time ratio is in the range of 0.1 to 1,
In addition, the alternating cycle is 1 to 50 Hz, the total processing time ratio is 0 seconds, the anodic electrolytic current density of the Zn-Ni alloy plated material is 5 to 100 A/drr+', and the anode 7' current density and cathodic electrolytic current density are After electrolytic treatment with a ratio of 1:0.1 to 1, chromate treatment is performed with a chromate solution containing chromic anhydride as the main component, and the chromate film is deposited at a concentration of 5 to 100.mg/m2 in terms of C. After dry weight of water-dispersible or water-soluble resin or silicic acid sol,
．． Provided is a method for producing a surface-treated steel material with a high degree of blackening by an alternating electrolytic method characterized by coating at a rate of 3 to 3 g/rrf.

The present invention will be explained in detail below.

The Zn-Ni alloy plating material containing 5 to 20% Ni, which is the object of the present invention, may be manufactured by any plating method such as electroplating, hot-dip plating, or vapor deposition plating. The base material to be plated may be a steel plate, an aluminum plate, a stainless steel plate, or the like.

In addition, the above-mentioned 7. containing 5 to 20% Ni. Various types of plating may be applied to the F layer of the n-Ni alloy plating layer, as long as the n-Ni alloy plating layer is directly deposited on the surface layer at a rate of 10 to 40 g/ff12. This is because if the plating layer is less than lOg/+n2, the corrosion resistance will be poor, and if it is 40g/lT12M, the workability will be poor.

The Ni content of the Zn-Ni alloy plating is preferably 5 to 20%. If the Ni content is less than 5%, black color cannot be obtained;
This is because if the Ni content is too high, the plating layer becomes hard and brittle, resulting in poor workability.In order to obtain a stable and good black color, the Ni content is preferably 7 to 18%.

In the present invention, the Zn--Ni alloy plating material is subjected to surface treatment with a high degree of blackening by alternating electrolysis in a treatment solution containing nitrate ions.

In the alternating electrolytic method, the time for holding the zn-Ni alloy plating material on the anode and cathode is set in the range of 0.1 to 1 for the cathode holding time for the anode holding time of 1, and the total treatment time ratio is 0 seconds. .

The anodic electrolysis current density of the An-Ni alloy plated material using alternating electrolysis is 5 to 100 A/drr? Zn
The cathodic electrolysis current density of the material with N+gold alloy is 0.1 to 0.5 with respect to the anodic electrolysis current density 1.

The alternating period is preferably in the range of 1 to 501 (z).

The reasons for limiting each of the above conditions are described below.

Regarding the alternating electrolysis time, as shown in Figure 1, if the cathode treatment time is OI ~ 1 for the anode treatment time 1, a good black color can be obtained, or if it is less than 0.1, a black color with an 11F taste will be obtained. This results in poor film adhesion and severe deterioration of the processing solution. If the time ratio exceeds 1, the formation of the blackened film will be delayed and the L value will become high, making it impossible to process within a total processing time of 1 to 30 seconds.

If the alternating period is less than 1) IZ, the black color will not be uniform and the appearance will be poor. If it exceeds 5011z, the polarity changes before electrolytic equilibrium is reached, so the rate of formation of the black layer slows down, making it impossible to obtain a black color.

Next, the anodic electrolytic current density is 5 8/ as shown in Figure 2.
If d is less than d, the plating layer will dissolve more and the formation of the black layer will be delayed.

If it exceeds 100 Δ/drrr', the black layer production efficiency will similarly deteriorate.

What is the ratio between the current density and the cathodic electrolysis current density for anodic electrolysis '1?
As shown in the figure, if it is less than 1.0.1, the uniformity of the +,j1 color layer will be lost and the adhesion will be poor.

If it exceeds 11, the formation of the black layer will be significantly slowed down.

After alternating electrolytic treatment under the above conditions, for corrosion resistance,
Chromate treatment and chromate film Gj11fi
It is preferable to deposit 5 to 1001 I]g/rr+' in total.

The chromate treatment method does not need to be particularly limited, and any known reaction-type chromate, coating-type chromate, electrolytic chromate, etc. can be used. C: At less than 5mg/rrf, there is no chromate treatment effect and there is no improvement in corrosion resistance.100
Even if it exceeds mg/m', the corrosion resistance will be saturated, and the adhesion of the coating film will deteriorate when resin coating, painting, etc. are performed.

By applying a water-dispersible or water-soluble resin or silicic acid sol after the alternating electrolytic treatment or after performing the chromate treatment after the alternating electrolytic treatment, it is possible to increase the depth of the black color and significantly improve corrosion resistance. can. The coating rate of these resins and silicic acid sol is 0.3 to 3 geIi2
(dry weight) range is good. If it is less than 0.3 g/ln2, the above-mentioned effect will not be obtained by coating. If it exceeds 3 g/m2, the appearance will be good, but weldability will be extremely poor. Examples of water-dispersible or water-soluble resins include carboxylated polyethylene resins, acrylic resins, epoxy resins, polyurethane resins, and melamine resins.

The difference between the alternating electrolysis method and the simple anodic electrolysis method is as follows.

That is, in the anodic electrolysis method, there is only a reaction of dissolving the metal surface, and the dissolved metal ions accumulate in the electrolyte, causing the electrolyte to deteriorate. In the alternating electrolysis method of the present invention, metal ions dissolved during anodic electrolysis are electrodeposited onto the metal surface again during cathode electrolysis, so accumulation of metal ions in the electrolyte can be suppressed and the life of the electrolyte can be extended. It will be significantly longer and the loss of plating metal will be kept to a minimum.

In addition, in the alternating electrolysis method, since melting → electrodeposition → dissolution is repeated, electrodeposition occurs on convex surfaces during electrodeposition, and as a result, it is easy to form fine craters. can be converted into

<Example> Next, the present invention will be explained in more detail based on examples.

[Examples and comparative examples]

Zn--Ni alloy plated steel sheets were treated using the treatment solution having the composition shown in Table 1 and the treatment conditions to obtain various blackened surface-treated steel sheets. A test piece was taken from the obtained blackened surface-treated steel plate, and
As performance evaluations, blackness, corrosion resistance, adhesion, film adhesion, black durability, film strength, and weldability tests were conducted, and the results shown in Table 1 were obtained.

Each performance test method and its evaluation were performed using the following methods.

In addition, since the comparative example has a very high degree of blackness (L value) and is not blackened, the following test was conducted only for weldability.

〔Test method〕

(1) Blackness The color JJL, a, and b values were measured using a 5M color computer manufactured by Suga Test Instruments Co., Ltd., and evaluated using the L value as an index to express the blackness of the surface of the steel sheet subjected to blackening treatment. . The L value is divided into 0 to 100 levels, and generally, the higher the L value, the whiter the color, and the lower the L value, the blacker the color.

(2) Corrosion resistance test A salt water cinder test was conducted on the flat plate portion and the 90° bent portion. The salt spray test was conducted in accordance with JIS-Z-2371. The test pieces were evaluated based on the time it took to seal the end face and reach 5% of the total area of white rust.

(3) Additive test (a) DuPont impact test: diameter 12.7 mm (1/
A 2 inch) punch is used to drop a weight of I kg from a height of 50 cm, and adhesive tape is applied to the impact γ part to peel off the film. Evaluation was made based on the degree of peeling of the film.

(b) Erichsen extrusion test: A steel plate is extruded to a depth of 6 mm using an Erichsen extrusion tester, and Sellotape is adhered to the convex portion, and a portion of the skin is peeled off. Evaluation was made based on the degree of peeling of the film.

Evaluation ◎: No peeling ○: Several % peeling △: 10 to 30% peeling ×: 31% or more peeling (4) Cut 100 2 mm square openings into the adhesive film of one piece of skin with a cutter knife. and peel off the film by applying cellophane tape to these 100 squares. Evaluation was made based on the number of peeled holes as follows.

, f value 5: Evaluation of no peeling 4: Peeling first, number of pieces 1 to 10 pieces 3f value 3: Peeling [number of pieces 11 to 30 pieces measured value 2: Peeling first, number of pieces
Evaluation of 31 to 50 pieces 1: No peeling, no more than 51 pieces (5) Black durability test Only irradiated with ultraviolet light using a sunshine weather meter.
Tested for 240 hours. Exam+if? The color tone (L, a, b values) of the surface of the & test piece was measured, and the color difference ΔE was determined. When the ΔE value is 0.5 F or more, the durability is extremely excellent.

△E; (6) Film strength test A load of 2 kg was applied to the surface of a 10 x 20 +++ m filter paper, and 10
The film was reciprocated 100 times at a distance of cm, and the degree of peeling of the film due to this pressure was observed and evaluated as 3F.

Evaluation ◎ No peeling ○: Slight peeling △: Slight peeling x 9 peeling in pieces 7) Weldability test Welding used R = Spot welding machine (semi-synchronous type) % formula % Welding current: 05 KA increments from 5 to 12 to 8 change.

Welding was carried out under the welding conditions described above, and evaluation was made based on the welding current range from nacket formation to welding with the electrode and the degree of splintering.

1. The wider the range of the welding current range, the better the occurrence of splintering.Evaluation at the welding current value at which splattering began.A: Near or above, failure occurs.B: 5.5 to 65, 8:8, failure occurs.C: 5 The blackness of the Zn-Ni alloy plated material was insufficient and only a black color close to gray could be obtained using the conventional blackening treatment method. It was necessary to add organic substances such as polyvinyl alcohol during plating. Furthermore, in the blackening treatment by anodic oxidation, the electrolyte deteriorates in a short time because dissolved metal accumulates in the electrolyte.

According to the present invention, a deep black color (L value of 13 or less) can be easily obtained even with Zn-Ni alloy plating. Another major advantage is that deterioration of the electrolyte can be significantly suppressed.

Furthermore, it has excellent properties such as weldability, corrosion resistance, blackness, and black durability, so it can be widely used in home appliances, copying machines, automatic whitening materials, etc.

[Brief explanation of the drawing]

Figure 1 shows the ratio of anodic treatment time to cathodic treatment time and skin 11
3 is a graph showing the relationship between adhesiveness and blackness. FIG. 2 is a graph showing the relationship between anode current density, film adhesion, and blackness. FIG. 3 is a graph showing the relationship between the ratio of anode current density to cathode current density and film adhesion and blackness.

Claims (4)

[Claims] (1) After applying 10 to 40 g/m^2 of Zn-Ni alloy plating containing 5 to 20% Ni to steel material, the Zn-Ni alloy plating material is placed on the anode and cathode in a treatment solution containing nitrate ions. The holding time is set to a ratio of 0.1 to 1 for the cathode treatment time to the anode treatment time of 1, and the alternating period is set to 1 to 50.
Hz, the total processing time was 1 to 30 seconds, and the Zn-
The anodic electrolytic current density of Ni alloy plating material is 5 to 100 A/
dm^2 and the electrolytic treatment is carried out at a ratio of anode current density to cathode current density of 1:0.1 to 1. (2) After applying 10 to 40 g/m^2 of Zn-Ni alloy plating containing 5 to 20% Ni to steel material, the Zn-Ni alloy plating material is placed on the anode and cathode in a treatment solution containing nitrate ions. The holding time is set to a ratio of 0.1 to 1 for the cathode treatment time to the anode treatment time of 1, and the alternating period is set to 1 to 50.
Hz, the total processing time was 1 to 30 seconds, and the Zn-
The anodic electrolytic current density of Ni alloy plating material is 5 to 100 A/
dm^2 and the ratio of anode current density to cathode current density is 1:0.1 to 1. After electrolytic treatment, chromate treatment is performed with a chromate solution containing chromic anhydride as the component to form a chromate film. 5 to 100 mg/m^ in terms of Cr
2. A method for producing a surface-treated steel material with a high degree of blackening by an alternating electrolytic method, which is characterized by adhesion. (3) After applying 10 to 40 g/m^2 of Zn-Ni alloy plating containing 5 to 20% Ni to steel material, the Zn-Ni alloy plating material is applied to the anode and cathode in a treatment solution containing nitrate ions. The holding time is in the range of 0.1 to 1 for the cathode treatment time to the anode treatment time of 1, and the alternating period is 1 to 50 hours.
z, the total processing time is 1 to 30 seconds, and the Zn-N
i The anodic electrolytic current density of the alloy plating material is 5 to 100 A/d.
m^2 and electrolytic treatment with a ratio of anode current density to cathode current density of 1:0.1 to 1, and then a water-dispersible or water-soluble resin or silicic acid sol with a dry weight of 0.3
A method for producing a surface-treated steel material with a high degree of blackening by an alternating electrolytic method, characterized in that the coating is applied at a rate of ~3 g/m^2. (4) After applying 10 to 40 g/m^2 of Zn-Ni alloy plating containing 5 to 20% Ni to steel material, the Zn-Ni alloy plating material is placed on the anode and cathode in a treatment solution containing nitrate ions. The holding time is set to a ratio of 0.1 to 1 for the cathode treatment time to the anode treatment time of 1, and the alternating period is set to 1 to 50.
Hz, the total processing time was 1 to 30 seconds, and the Zn-
The anodic electrolytic current density of Ni alloy plating material is 5 to 100 A/
dm^2 and electrolytic treatment with a ratio of anode current density to cathode current density of 1:0.1 to 1, and then chromate treatment with a chromate solution containing chromic anhydride as the main component to form a chromate film. 5 to 100 mg/m^ in terms of Cr
2. Surface treated steel material with a high degree of blackening by an alternating electrolytic method characterized by applying a water-dispersible or water-soluble resin or silicic acid sol at a dry weight of 0.3 to 3 g/m^2 after adhesion. Production method.