JP3027118B2 - Vertical electroplating apparatus and electrochrome plating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroplating apparatus and a plating method for plating a metal strip (hereinafter, referred to as a strip) such as a steel strip by electrolysis, and more particularly to a method for uniformly depositing a strip in the width direction of the strip. The present invention relates to a vertical electroplating apparatus capable of performing electroplating and an electrochromic plating method using the apparatus.

[0002]

2. Description of the Related Art In a plating apparatus, a strip of steel strip or the like is immersed in a plating solution, and a pair of electrodes are arranged with the strip interposed therebetween. The way to get
The following methods or devices are known.

[0003] A method in which a plurality of holes are provided in an electrode portion to promote inflow of a plating solution. A method in which a plating solution jet nozzle is installed in an electrolytic cell to improve current efficiency. A method of promoting renewal of a liquid by dividing a plurality of electrodes in a longitudinal direction and providing a protrusion made of an insulator at a boundary portion.

[0004] In a plating tank having an electrode wider than the width of the steel strip, a shield that can be expanded and contracted so as to shield the end of the steel strip is disposed to overcoat the end of the steel strip. Prevention method (JP-A-60-258496). Electroplating equipment having a pair of opposing static pressure pads provided with a plating solution jet opening opening toward the strip surface and an electrically insulating edge mask covering a side end of the strip (Japanese Patent Application Laid-Open No. 61-199004) .

The above methods (1) to (5) activate the renewal of the plating solution in the vicinity of the strip surface, and in particular, the method (3) obtains highly efficient and uniform plating by uniformly renewing the plating solution in the width direction of the plate. Is aimed at. However, this method has a problem that the accompanying flow from both sides of the strip is stronger than the flow from the hole in the electrode portion, so that the renewal of the liquid in the width direction of the strip plate becomes non-uniform, which affects the plating adhesion amount.

However, the above method has a problem that the equipment is complicated, and there is a problem that the cost for modifying the conventional equipment is too high. In the methods of (1) and (2), since both end portions of the strip plate are shielded by the shields, there is a problem that the strip ends come into contact with the shields particularly when the line speed is increased, so that the sheet cannot be stably passed.

In addition, the vertical electroplating apparatus according to the present invention, in which a pair of electrodes are vertically opposed to each other, is different from the horizontal cell type electroplating apparatus in terms of gas release of generated gas and space for equipment. Although excellent in terms of compactness, as described later, due to the uneven distribution of streamlines formed by the flow of the electrolyte, the amount of plating applied in the width direction of the strip plate has a distribution, which must be resolved. Was.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention, the conventionally solve the technical problems, a simple device, allows uniform plating in the plate width direction of the metal strip such as a steel strip, moreover high current efficiency vertical It is an object of the present invention to provide a type electroplating apparatus and a plating method.

[0009]

According to a first aspect of the present invention, a metal strip is immersed in a vertical electrolytic plating tank filled with an electrolytic solution, and the strip is sandwiched between the front surface (front surface) and the back surface. In a vertical electroplating apparatus in which a pair of plate electrodes are arranged at symmetrical positions relative to each other and plating is performed by electrolysis, both sides of the opposite plate electrodes in the strip plate width direction are covered with an electrical insulator. A vertical electroplating apparatus characterized in that inflow of electrolyte from both sides of the electrode is prevented.

In the first aspect of the present invention, on the plate surface of the plate-like electrode, in the width direction of the strip, more preferably, on a straight line perpendicular to the traveling direction of the strip.
Preferably, a plurality of electrolyte inlets are provided. Examples of the form of the plating solution inlet in this case include a hole-like inlet and a slit-like inlet provided in parallel with the traveling direction of the strip.

As means for forming the slit-shaped inflow port, the plate-like electrode is formed by dividing the plate-like electrode into a plurality of pieces in the width direction of the strip and having a gap between these electrodes. It may be. Further, the present invention is more preferably applied to a vertical electroplating apparatus in which the plate electrode is an insoluble anode.

Further, the present invention provides the above-mentioned plate-shaped electrode and the electrode.
The cross-sectional shape of the electrolyte flow path surrounded by the gas insulator is rectangular or square.
That is, it is preferably rectangular or square. Ma
A second invention is directed to the vertical electroplating apparatus according to the first invention.
Characterized by performing chrome plating using a device
This is a chrome plating method. This second invention is more preferable.
In other words, the electrolyte composition is CrO_ThreeConcentration: 10-100g / l, H_TwoSO _FourDark
Degree: 0.1-1g / l, line speed: 50-600m.p.m. Electricity
It is preferably applied to a chromium plating method.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present invention is preferably applied to a vertical electroplating apparatus in which a pair of electrodes are arranged vertically opposite to each other. Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the uniformization of the coating weight of the strip in the width direction of the strip in the vertical electroplating apparatus, focusing on the flow of the electrolytic solution on the strip surface, that is, the streamline of the electrolytic solution. As a result, the present invention has been achieved.

FIG. 6 is a side view of a conventional vertical immersion type electrolytic cell, and FIG. 7 is a sectional view of an electrode portion. 6 and 7, 1 is an energizing roll, 2 is a sink roll, 3 is a strip (steel strip), 4, 4a, 4b, 4c, 4d are electrodes, 5 is an electrolytic cell,
Reference numeral 6 denotes an electrolytic solution, and reference numeral 10 denotes a strip traveling direction.

The strip 3 is conveyed through the electrolytic roll 5 filled with the electrolytic solution 6 via the energizing roll 1 and the sink roll 2, and is subjected to electroplating between the electrodes 4a and 4b and between the electrodes 4c and 4d. You. At this time, between the electrodes 4a and 4b and between the electrodes 4c and 4d
The flow of the electrolytic solution 6 in the vicinity of the strip 3 between the strips 3 is drawn to the traveling strip 3, and as shown in FIG.
A new electrolytic solution 6f flows from both sides of the strip 3 in the width direction W of the strip 3 into the space between the electrodes 4a and 4b and between the electrodes 4c and 4d in the direction indicated by the stream line F from the outside of the electrodes.

As a result, various ions in the electrolytic solution 6c near the center of the strip 3 in the plate width direction are consumed on both sides in the plate width direction of the strip 3, and the ion concentration in the electrolytic solution is reduced. It becomes uneven in the width direction, and the current efficiency at the center of the strip 3 decreases. This is because the current efficiency depends on the ion supply amount.

Also, this phenomenon is caused by a vertical type electroplating apparatus which does not have a plating solution supply nozzle and a plating solution circulating device in the plating solution flow path between the electrodes of the plating tank. This poses a problem in a vertical electroplating apparatus performed by passing a sheet. Also, the electrodes 4a, 4b,
When insoluble anodes are used as 4c and 4d, metal ions as plating components and ions of auxiliary agents are carried by the liquid flow. Non-uniformity occurs and becomes a problem.

Further, in a plating bath containing CrO ₃ and H ₂ SO ₄ used in the production of an electrochromic steel sheet used as a material for cans, it is important to make the distribution of the electrolytic solution uniform. This is because, in this case, the current efficiency greatly differs depending on the ion concentration ratio of Cr and H ₂ SO ₄ in the electrolytic solution, and if the liquid flow distribution is uneven, the position unevenness of the ion concentration ratio occurs. As a result, it is considered that a large variation occurs in the amount of Cr precipitated in the width direction of the strip 3.

The present invention has been made in order to solve the above problems.
A vertical electroplating apparatus in which a pair of opposed plate-like electrodes of a vertical electroplating apparatus are covered with an electrical insulator on both sides in the strip plate width direction to prevent inflow of electrolyte from both sides of the electrodes; and This is an electrochromic plating method using the apparatus. In the present invention, it is preferable to provide a plurality of electrolyte inlets on the plate surface of the plate-like electrode in the width direction of the strip.

In this case, more preferably, a plurality of strips are formed on the plate surface of the plate-like electrode on a straight line intersecting with the traveling direction 10 of the strip, and more preferably on a straight line orthogonal to the traveling direction 10 of the strip. Is preferably provided. This is because, with this configuration, the liquid flow distribution (liquid flow direction and flow velocity distribution) of the electrolytic solution in the strip width direction becomes parallel and uniform to the strip traveling direction 10.

One example of an electrode used in the electroplating apparatus of the present invention is shown in a sectional view in FIGS. FIG.
Shows a cross-sectional view cut at a location where no electrolyte inlet exists, and FIG. 2 shows a cross-sectional view cut at a location where an electrolyte inlet exists. 1 and 2, reference numeral 7 denotes an electric insulator, 8 denotes an electrolyte inlet, and other reference numerals denote the same contents as in FIGS.

In FIGS. 1 and 2, three circular electrolyte inlets 8 are provided on a straight line perpendicular to the traveling direction of the strip 3. As shown in FIGS. 1 and 2, in the present invention, opposed electrodes 4 a and 4
b, and the side surfaces on both sides of the electrode plates of the electrodes 4c and 4d are covered with an electric insulator 7, and preferably, a plurality of plating solution inlets 8 are provided on the plate surface of the electrode plate in the width direction of the strip plate. It is preferable that the cross-sectional shape of the electrolytic solution flow path of the electrode portion on which the strip 3 runs is rectangular.

With this configuration, the flow direction of the electrolyte near the both ends in the width direction of the strip 3 is
This is because the direction becomes parallel to the traveling direction of the strip 3 and the flow rate of the electrolyte becomes uniform in the width direction of the strip 3. As the electric insulator in the present invention, butyl rubber, chlorosulfonated polyethylene rubber, acid-resistant rubber such as fluorine rubber, acid-resistant resin such as vinyl chloride resin, electric insulating material such as ceramics and the like. An electric insulator composed of an acid-resistant electric insulating material is preferable.

The electroplating apparatus according to the present invention, having the above-described configuration, prevents the inflow of the electrolyte from both sides in the width direction of the strip plate, and allows the electrode 4 illustrated in FIGS.
From the electrolyte inlets 8 provided in the a, 4b, 4c, 4d, the electrolyte 6 is formed by the electrodes 4a, 4b and the strip 3 in the direction shown in FIG. Four
The electrolyte flows into each of the electrolyte channels formed by c, 4d and strip 3.

The electrolyte flowing into each of the electrolyte channels is:
In the vicinity of the strip 3 between the electrodes 4a and 4b and between the electrodes 4c and 4d, as shown in FIG.
And flows at a uniform velocity in the strip plate width direction W. Along with this, the conventional phenomenon that when the plating solution flows in from both sides in the width direction of the strip, the renewal of the electrolyte in the center portion in the width direction of the strip is insufficient compared with the both sides of the width of the strip, is solved. This makes it possible to uniformly update the plating solution in the width direction of the plate, that is, to supply ions.

As a result, according to the electroplating apparatus of the present invention, the current efficiency becomes uniform in the strip plate width direction, and it is possible to obtain a uniform plating adhesion amount in the plate width direction.
Further, according to the present invention, the current efficiency at the center in the width direction of the strip is improved, so that the power consumption can be reduced.
The apparatus of the present invention is preferably applied to a vertical electroplating apparatus in which the plate-like electrode is an insoluble anode.

This is because the direction of the flow of the electrolytic solution in the width direction of the strip plate is substantially parallel to the traveling direction of the strip, the distribution of the flow rate of the electrolytic solution in the width direction of the strip plate becomes uniform, It is considered that the density becomes uniform in the plate width direction. As the insoluble anode in the present invention, on the surface of a conductive substrate such as Ti, Ta, Nb, Zr, Hf, V, Mo, W or an alloy thereof, Ir, Pt,
An electrode coated with a platinum group metal such as Ru or an oxide thereof such as IrO ₂ is preferably exemplified.

Further, the apparatus according to the present invention can be used for electrochromic plating.
It is preferably applied to It uses the device of the present invention
As a result, Cr and H_TwoSO_FourIon concentration ratio with
Is uniform in the width direction of the strip
Current efficiency depending on the power ratio becomes uniform in the plate width direction.
Conceivable. The device of the present invention is more preferably an electrolytic solution
The composition is CrO_ThreeConcentration: 10-100g / l, H_TwoSO _FourConcentration: 0.1-1g /
l, Line speed: 50-600m.p.m. for electrochrome plating
It is preferably applied.

[0029]

The present invention will be described below in more detail with reference to examples. After the cold-rolled steel strip was subjected to alkali degreasing and sulfuric acid electrolytic pickling, continuous electrochromic plating was performed using the vertical electroplating apparatus shown in FIG. 4 under the following plating conditions. In the vertical electroplating apparatus shown in FIG. 4, the flow paths of the electrolyte 6 composed of the electrodes 4a and 4b and the electrodes 4c and 4d are all the electrodes 4a (4c) shown in FIGS. 4b (4d), a flow path composed of the electric insulator 7.

Further, as each of the electrodes 4a to 4d, an insoluble electrode having Ti as a conductive base was used, and as a material of the electric insulator, a vinyl chloride resin was used. Plating bath composition: CrO ₃ 50 g / l, H ₂ SO ₄ 0.4 g / l Plating bath temperature: 40 ° C. Current density: 40 A / dm ² Line speed: 400 m.pm Width direction of the obtained chrome-plated steel strip FIG. 5 shows the metal Cr deposition efficiency.

FIG. 5 also shows the metal Cr deposition efficiency when the conventional electrode shown in FIG. 7 is used. The metal Cr deposition efficiency η shown in FIG. 5 was obtained from the following equation (1). η = [(St) / (JL)] × 186 (%) (1) where, S: line speed [m / min], t: plating adhesion per one side of steel strip Amount [g / m ² ], J: Current density [A / d
m ² ], L: The length [m] of the energized plating path.

As shown in FIG. 5, it can be seen that by applying the present invention to chromium plating, the precipitation efficiency of metallic Cr becomes uniform in the width direction of the steel strip.

[0033]

According to the present invention achieved by paying attention to the flow of the electrolytic solution in the electrolytic solution flow path, when electroplating is performed using a vertical electrolytic cell, the flow of the electrolytic solution between the electrodes is made of metal. It was possible to make uniform in the width direction of the strip plate, whereby the current efficiency was made uniform in the width direction of the strip plate, and it became possible to make the amount of plating applied uniform.

In addition, since the current efficiency at the center of the strip in the plate width direction is increased, there is an effect that the power consumption can be reduced as a result.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an electrode used in a vertical electroplating apparatus of the present invention.

FIG. 2 is a schematic diagram showing a flow of an electrolytic solution in a cross section between electrodes of an electrode used in a vertical electroplating apparatus of the present invention.

FIG. 3 is a schematic diagram showing a flow of an electrolytic solution on an electrode surface of an electrode used in the vertical electroplating apparatus of the present invention.

FIG. 4 is a side view showing an example of the vertical electroplating apparatus of the present invention.

FIG. 5 is a graph showing the metal Cr precipitation efficiency of a chromium-plated steel strip in the width direction of the steel strip.

FIG. 6 is a side view showing a conventional vertical electroplating apparatus.

FIG. 7 is a side view showing an electrode used in a conventional vertical electroplating apparatus.

FIG. 8 is a schematic diagram showing a flow of an electrolytic solution on an electrode surface of a conventional vertical electroplating apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current supply roll 2 Sink roll 3 Steel strip 4, 4a, 4b, 4c, 4d Electrode 5 Electrolyzer 6 Electrolyte 7 Electric insulator 8 Plating solution inlet 10 Strip traveling direction 6f New electrolyte 6c Central part of strip width direction Nearby electrolyte F Electrolyte streamline W Strip width direction

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-90684 (JP, A) JP-A-3-97895 (JP, A) JP-A-3-96353 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) C25D 5/00-7/12 C25D 17 / 12,21 / 10

Claims (5)

(57) [Claims] 1. A metal strip is immersed in a vertical electroplating tank filled with an electrolytic solution, and a pair of plate-like electrodes are arranged at symmetrical positions with respect to the front and back surfaces of the strip with the strip interposed therebetween. Then, in the vertical electroplating apparatus for performing plating by electrolysis, both sides of the opposite plate-shaped electrode in the width direction of the strip plate are covered with an electric insulator to prevent the inflow of the electrolyte from both sides of the electrode. A vertical electroplating apparatus characterized by the following. 2. A plurality of electrolyte inlets are provided on a plate surface of the plate-like electrode in a plate width direction of the strip.
The vertical type electroplating apparatus as described in the above. 3. The vertical electroplating apparatus according to claim 1, wherein the plate-like electrode is an insoluble anode. 4. The vertical electroplating apparatus according to claim 1, wherein a cross-sectional shape of the electrolytic solution flow path surrounded by the plate-shaped electrode and the electric insulator is rectangular. 5. An electrochromic plating method, wherein chromium plating is performed using the vertical electroplating apparatus according to claim 1.