JPS60121299A - Nickel plating method - Google Patents

Abstract

PURPOSE:To carry out continuously and economically nickel plating in uniform thickness by using a plating bath contg. a nickel ion coexisting with a compd. contg. sulfur, and plating while replenishing with the nickel ion as much as consumed. CONSTITUTION:A plating bath contg. nickel rhodanate as nickel ions and a sulfure-contg. compound is used in a plating cell 1, and the nickel plating is carried out by using an insoluble anode. A part of said plating bath is taken out and transferred into an anodic chamber 4 which is formed by separating an electrolytic cell 2 with a cation-exchange membrane 3. A soln. of an electrolyte is filled into a cathodic chamber 5, and a current is passed. Nickel is eluted from an anode 6 to increase the nickel concn. in said plating bath, and the liquid is circulated to the plating cell 1. Nickel is replenished by the amt. corresponding to the amt. of consumed nickel in this way without losing the balance of composition in the plating bath. The plating is carried out economically and uniformly without disposal of the plating bath.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nickel plating method. Specifically, the present invention relates to a plating method suitable for producing a nickel-plated electrode with extremely low hydrogen overvoltage and good durability.

Since then, nickel plating has been used to improve the corrosion resistance of metals such as iron materials and curved die-casting, and for decorative purposes. These are usually plated using a plating bath called a Watt bath or an ordinary bath, so that an extremely dense plating layer can be obtained. In recent years, alkali metal salts,
For example, in the alkaline electrolysis industry that electrolyzes aqueous solutions of sodium chloride or potassium chloride, or the water electrolysis industry, a rodan nickel bath or a nickel plating bath containing other sulfur-containing compounds is used as a cathode with a small hydrogen overvoltage.
Nickel-plated electrodes are known.

As a manufacturing method of these electrodes, for example, Japanese Patent Publication No. 57-1
Usually, the invention described in Publication No. 1397 has been proposed,
Decorative nickel plating uses nickel metal as the anode and the object to be plated as the cathode, so the nickel ions in the plating are constantly replenished by elution from the anode, and the nickel ion concentration in the bath remains virtually constant. can be kept. In this case, if the object to be plated is relatively flat, substantially uniform plating can be obtained, but if the object to be plated has a complicated shape, the current density will vary on the surface of each part of the object to be plated. This causes unevenness in the thickness of the nickel plating. If the purpose is simply for decoration or corrosion prevention, even if such unevenness occurs, a plated product with substantially no problems can be obtained by plating relatively thickly.

However, for the purpose of manufacturing electrodes, which is the main object of the present invention, such thickness unevenness is extremely inconvenient. That is, when using a sulfur-containing compound nickel bath, the plated surface is generally hard and micro-cracks are likely to occur, so uneven thickness can easily cause the plating to peel off, so the current distribution on the surface of the plated object should be The shape of the anode, which is the opposite electrode to the object to be plated, is an important factor in order to uniformly perform the nickel treatment. However, changing the shape of the nickel anode to be eluted to match the shape of the object to be plated is complicated, and It is also inherently unsuitable because the shape changes accordingly.

Therefore, when plating using a sulfur-containing compound nickel plating bath, especially when plating is performed for the purpose of creating a cathode for use in electrolyzing alkali metal salts, an insoluble anode is usually used for the object to be plated. In general, a sulfur-containing nickel salt must be used as a sulfur-containing compound in a plating bath. In this case, as plating progresses, nickel ions and sulfur-containing compounds or their ions in the bath are consumed, but the consumption of nickel ions is extremely large compared to other components, and compared to other ions, nickel ions are consumed. The entire plating bath solution must be renewed as the concentration drops rapidly and plating performance deteriorates. Of course, it is also possible to continuously extract a certain amount of the solution and introduce a new plating bath solution containing a sulfur-containing nickel compound, etc., but in any case, the bath solution containing a considerable concentration of nickel ions must be discharged. .

In addition, since various expensive chemicals are generally used in nickel plating baths containing sulfur-containing compounds, it is desirable to use them effectively, since discarding these chemicals would be an economical loss. Therefore, the present invention supplies nickel ions to a sulfur-containing compound nickel plating bath solution in which only the nickel ion concentration has been reduced so as to maintain the balance with other compositions within a certain range, thereby effectively performing sulfur-containing compound nickel plating. Offer something to do.

That is, when performing nickel plating in a plating bath in which nickel ions and sulfur-containing compounds coexist, the present invention replenishes an amount equivalent to the nickel ions consumed by the plating without impairing the composition balance of other plating baths. This is a nickel plating method characterized by the following.

According to the method of the present invention, only the nickel ions consumed in the plating bath are replenished, and other ions such as sulfur-containing compounds can be used as they are for a relatively long period of time, making the preparation of the plating bath less complicated and more efficient. This method is effective and economical, and since the plating bath maintains almost the same compositional balance as the initial state, uniform nickel plating can be performed continuously. Therefore, it is possible to obtain a cathode with particularly low hydrogen overvoltage and good durability.

The plating bath used in the present invention is not particularly limited as long as nickel ions and sulfur-containing compounds coexist. Examples of nickel ions include organic or inorganic soluble nickel salts such as nickel chloride, nickel sulfate, nickel nitrate, nickel rhodan, nickel acetate, nickel thiosulfate, nickel trifluoroacetate, and nickel nicotinate. Rodan nickel is particularly suitable. In addition, the sulfur-containing compound in the present invention is a general term for water-soluble compounds containing the sulfur element or atomic groups (including ions) containing sulfur, such as rhodan ion, thiosulfate ion, thiocarbamate ion, and thylcarboxylate ion. , anions such as sulfur ions, thiourea, thiocarbamoyl compounds, and other soluble sulfur-containing compounds, which exist in a form below the maximum oxidized state of sulfur. Therefore, examples of sulfur-containing compounds include rhodan salts such as rhodan nickel, rhodan ammonium, rhodan potassium, and rhodan sodium; thiosulfates such as potassium thiosulfate, sodium thiosulfate, and nickel thiosulfate; sodium thiocarboxylate, and thiocarboxylic acid. Thiocarboxylic acid salts such as potassium and nickel thiocarboxylate; xanthates such as nickel xanthate; soluble sulfur compounds such as sodium sulfide and sodium polysulfide; or water-soluble sulfur-containing compounds such as thiourea and thiocarbamoyl compounds are effective. provided. Among these sulfur-containing compounds, nickel salts such as rhodan nickel and thio[WIi nickel are suitable as they can be effectively used as nickel ion sources for nickel plating. In particular, in order to obtain a cathode with a low hydrogen overvoltage according to the present invention, it is preferable to use a sulfur-containing compound containing sulfur and nitrogen, such as rhodan nickel. moreover,
As described in Japanese Patent Publication No. 57-11397, the plating bath of the present invention contains, in addition to the sulfur-containing compound, a complexing agent,
Electrodeposition accelerators such as ammonium and boric acid may be added as necessary. As the complexing agent, oxycarboxylic acids such as glycolic acid, lactic acid, glyoxal, tartaric acid, malic acid, and citric acid are suitable. Of course, in addition to the above-mentioned ions, the plating bath of the present invention also contains 5o4F-1.
Anions that enhance the effectiveness of the plating of the present invention or are harmless, such as CI-, may also be present.

The present invention is characterized in that when performing nickel plating using the above plating bath, the balance of the bath composition of the plating bath is maintained by replenishing only the nickel ions consumed by the plating. Of course, due to nickel plating, the concentration of other than nickel may change somewhat, and in that case, it is possible to arbitrarily adjust it by replenishing the A and A component as needed.

A known method is used for the nickel plating method using a sulfur-containing compound of the present invention. That is, the plating bath composition, current density, temperature, and other plating conditions are as specified in the above-mentioned Japanese Patent Publication No. 57.
-11397 publication and others are used as they are. The counter electrode in the plating bath, that is, the anode, is insoluble and is generally made of expanded metal made of iron, nickel, stainless steel, or the like, or a plate-shaped material. Further, the shape of the anode may be appropriately determined depending on the shape of the object to be plated. Generally, it is preferable to use one that provides a uniform current distribution on the surface to be plated.

In the present invention, the method for replenishing nickel ions into the plating bath is other than the method of extracting a portion of the plating bath from the plating bath, bringing it into contact with a cation exchange resin that has adsorbed nickel ions, and then circulating it back into the plating bath. There is no particular restriction on the method as long as it does not impair the balance of other plating bath compositions. Generally, only nickel ions may be supplied continuously or intermittently from outside the system.

In the present invention, the balance between nickel ions and sulfur-containing compounds is particularly important as the plating bath composition balance, followed by pH fluctuation, the balance between a complexing agent used as desired, and nickel ions, etc. Follow)
In the present invention, if the nickel ions in the plating bath are consumed and reduced too much, good nickel plating cannot be achieved.
(sulfur-containing compound) molar ratio in a range larger than 1/4,
Preferably, it is desirable to maintain the ratio within the range of 1/;um~]/1.

In the present invention, the method for replenishing the plating bath with nickel ions is, for example, in the form of a nickel salt having anions that are not harmful to the plating bath solution. In other words, carbonate ions, which are anions that do not cause harm even if they coexist to some extent,
There is a method of adding it as a salt such as a chloride ion or a sulfate radical, or a method of separately providing an electrolytic bath for nickel elution and circulating a part of the plating bath solution therein. In an electrolytic cell for nickel elution, electricity is applied using a nickel anode and a cathode, such as iron carbon, which is difficult to deposit nickel on.

In this case, hydrogen may be generated at the cathode. In energizing and plating baths, as nickel is consumed, hydrogen ions are formed in the bath solution, which tends to make the bath solution acidic, but the above electrolysis can also adjust the hydrogen ion concentration. .

In another preferred embodiment, the plating tank is transferred from the plating tank to the anode compartment of the electrolytic tank for nickel elution, in which an anode compartment in which a nickel eluting anode (nickel anode) exists and a cathode compartment in which a counter electrode (cathode) exists are separated by an ion exchange membrane. The plating bath solution is circulated, and the cathode chamber is filled with an electrolyte solution such as common salt, and electricity is applied to elute nickel ions from the nickel elution anode. When a cation exchange membrane is used as an ion exchange membrane, the transport number of hydrogen ions in the membrane is extremely high compared to nickel ions, so it is essentially the hydrogen ions that pass through the ion exchange membrane, and the nickel will be supplied to the plating bath solution in the anode chamber. In this case, it is particularly preferable because anions will not enter the anode chamber from the cathode chamber side due to the cation exchange membrane. Further, even when the ion exchange membrane is an anion exchange membrane, nickel remains in the anode chamber and hydrogen ions migrate to the cathode chamber because of the easy permeability of the anion exchange membrane to hydrogen ions. In this case, some anions also migrate from the cathode chamber to the anode chamber, which may be undesirable depending on the case. It is also effective to select a relatively large anion as the anion present in the cathode chamber and to reduce the transmembrane transport number of the ion.

A typical example of using an ion exchange membrane will be explained with reference to the drawings. That is, in the first factor, a part of the solution whose concentration has decreased due to consumption of nickel ions in the plating bath is extracted from the plating bath, and nickel ions are replenished in the electrolytic bath 2 for nickel elution. The electrolytic cell 2 used at this time is composed of an anode chamber 4 and a cathode chamber 5 with a cation exchange membrane 3 in between, and each chamber is provided with an anode 6 made of metal nickel and a cathode 7 made of iron, carbon, etc. ing. In such an electrolytic cell, the plating solution is passed through the anode chamber 4 through the pipe 11, and a neutral salt solution such as salt water is passed through the cathode chamber 5 through the pipe 1.
2, electrolysis is performed by circulating the liquid as necessary. Since the metal nickel of the anode 6 is eluted by electrolysis, nickel ions are supplied into the plating solution in the anode chamber 4. Since the rate of nickel elution is determined by the amount of current applied, the amount of current may be adjusted according to the degree of plating. In addition, increasing the circulation speed of the plating solution is convenient for keeping the concentration in the plating tank uniform, but there are also disadvantages such as an increase in energy due to the increased circulation rate, so it should be considered depending on the equipment used. . Further, since the anode chamber 4 is separated from the cathode chamber 5 by the cation exchange B3, the sulfur-containing compounds of the plating bath solution will not permeate into the cathode chamber 5 and be damaged.

Therefore, by controlling the elution rate of metallic nickel from the anode 6, it is possible to replenish and prepare only the nickel ions in the plating solution in the anode chamber 5 to a predetermined concentration. As the cation exchange membrane 3, a hydrogen ion selectively permeable cation exchange membrane is preferably used. The plating bath solution whose nickel ion concentration has been adjusted in the nickel elution tank is returned to the plating tank. In this case, it is not possible to add other chemicals such as a pH adjuster as necessary.

Further, although FIG. 1 shows an embodiment in which the electrolytic cell for nickel elution is constructed using a cation exchange membrane, an anion exchange membrane can also be used. In this case, it is also preferable to use a catholyte having an anion similar to that of the plating bath composition, such as rodan ion, such as rodan nickel.

In addition, as shown in FIG. 2, the electrolytic cell 2 for eluting nickel is a three-chamber electrolytic cell equipped with a cation exchange membrane (K) and an anion exchange membrane (A), and the plating solution is supplied to the intermediate chamber 8 through piping 11. In order to improve the nickel consumption rate, it is also preferable to supply a plating bath solution with an increased nickel ion concentration in the intermediate chamber and return it to the plating tank via the pipe 13. In this case, by using an electrolyte containing sulfur-containing ions in the cathode chamber 5, it is also possible to prevent foreign anions from entering the intermediate chamber.

However, the present invention is not particularly limited to the above method.

Items that can be effectively plated by the method of the present invention generally have complex shapes, such as those that have a plurality of spaces in a flat tube-like network structure used for electrolysis of aqueous alkali chloride solutions by the diaphragm method. Suitable for plating cathode cans, etc.

EXAMPLES Hereinafter, the present invention will be explained in detail based on examples, but the present invention is not particularly limited to the following examples.

Example 1 A titanium plate (shape: 1100mm) plated with platinum (thickness: 3μ111mm) was placed as an anode in a plating bath as shown in Figure 1.
0a+X1000) with the same shape of expanded metal (
Table 2 shows the relationship between the number of plating times and the nickel ion concentration in the bath when plating was repeatedly carried out using a plating bath having the composition shown in Table 1 with a metal (iron) used as a cathode.

The plating conditions were a current density of 20 A/dm, a plating time of 30 minutes, a distance between electrodes: 2011II11, a plating bath solution size of 1 m, and a pump installed in the line to circulate the solution during plating. Ta. Further, when each plating was completed, the plating bath solution was passed through the same filter in the line to remove slime, etc., and then used for the next plating.

Table 1 Table 2 Note that the compositions other than Nt2° hardly changed during this plating.

Next, a cation exchange B (manufactured by Tokuyama Soda Co., Ltd., trade name: Neo Sebuta C5S-8'r) having a shape of 750 mm in height and 550 + am in width was installed in an electrolytic cell for nickel elution as shown by the symbol 2 in Fig. 1. Using an electrolytic cell consisting of an acrylic anode chamber and a cathode chamber sandwiched in the center, a nickel plate on the anode side and an iron plate on the cathode side (both 700 mm) were used as electrodes.
A plating bath solution having the composition shown in Table 3, in which the nickel ion concentration has been reduced by repeated plating, was pumped out from the plating tank and 20'? The supply and circulation were carried out at a rate of 17 minutes, while the cathode chamber was energized while slowly circulating a solution of 10 Horyu parts and cents of sodium chloride in a polyethylene tank with a pump. Temperature: 20 to 30°C), and the change in nickel ion concentration in the plating bath solution over time was measured. Table 4 summarizes the results.
It was shown to.

Table 3 After 180 minutes, the fifth plating was performed using the plating bath solution whose NI2 concentration had recovered to 0.425.

Table 4 When the hydrogen overvoltage of each of the active cathodes obtained by these methods was measured, the first plated electrode in Table 2 showed a voltage of 0.24V after 300 days at an initial voltage of 0.17V.
V, and the 5th one has an initial value of 0.18 V and 300
After one day, the voltage was 0.22 V.

Comparative Example 1゜In the plating step of Example 1, when a nickel plate was used as the anode and plating was performed repeatedly at 1, 1, the anode shape changed and the plated object/anode area ratio became 1 or more. Assuming that, the anode shape and 750mm x 500n+m
(The shape of the cathode is the same as before, 1000 mm x 10
An active electrode was manufactured by performing plating in exactly the same manner as in the first plating except that the active electrode was changed to 00s11). When we measured this hydrogen overvoltage, we found that it was 0.18V in the part that did not face the anode during plating, at the initial stage of energization.
After 100 days, it became 0.25 V. Further, when the thickness of the plating was measured using an optical microscope, the thickness of the part facing the anode was 20 μm, and the thickness of the part facing the anode was 8 μm.

On the other hand, when plating is performed with the object to be plated and the anode completely facing each other with an area of 1:1, the hydrogen overvoltage of the active electrode is 0.17 V at the initial stage of current application, and 0.0 V after 300 days.
, 22 V. Further, the plating thickness was almost uniform throughout and was 26 μm.

The hydrogen overvoltage was measured using a platinum-like material as the electrode (anode) and a 2 () weight percent sodium chloride solution (temperature:
Electrolysis (current density: 2OA/drn”) at 85°C)
However, it is approximated from the cathode electrode measured by the Luggin capillary method using a conventional method, compared with the mercury oxide electrode.

It is. In the figure, l is a plating tank, 2 is an electrolytic tank, 3 is a cation exchange membrane, 4 is an anode chamber, 5 is a cathode chamber, 6 is an anode,
7 is a cathode.

Patent Applicant: Tokuyama Soda Co., Ltd. Figure 1 Figure 2 Procedures Amendment Written April 1980 IB Commissioner of the Japan Patent Office Kazuo Wakasugi 1, Indication of Case Percentage Request No. 1982-225453 2, Title of the Invention Nickel plating method 3, relationship with the case of the person making the amendment Patent applicant address: 1-1-5, Mikage-cho, Tokuyama-shi, Yamaguchi Prefecture Number of inventions increased by the amendment None 6: “Patent claim” in the specification subject to the amendment "scope of the invention" and "detailed description of the invention"
Column Z Contents of amendment (1) The scope of claims is amended as shown in the attached sheet.

(2) "Tylcarboxylic acid ion" in the fourth line from the bottom of page 7 of the specification is corrected to "thiocarboxylic acid ion."

(3) In the fourth line from the bottom of page 8, "contains theft" is corrected to "contains 1 nitrogen."

(4) On page 10, line 1 of the same page, after “・mountain・・will be used as is”, the nickel ion concentration in the bath liquid is set to 0.1 to 0.2 m
It is preferable to perform plating by keeping the ol/l in a range of 3 to 1 mol/l and setting the current density to 20 A/dm or less and 60° C. or less to the object to be plated. Furthermore, the complexing agent
- in the case of 0.1 to 2 mol/l. Other drugs can be used as appropriate according to conventional methods. Insert J.

(5) On page 10, lines 3 to 5, "Expanded metal made of materials such as iron, nickel, or stainless steel, or processed as a plate-shaped body is preferable.""It's a piece of titanium that's processed into a shape and then plated with platinum."

(6) "Iron carbon" on page 11, line 16 of the same page is replaced with "iron."

Corrected to "Carbon."

←) On page 14, line 5 from the bottom, ``Returned to tank 1'' was corrected to ``Returned to tank.''

(8) rsc M page 17 table 1 r 5cy2-J
Corrected to N-J.

(9) (7) rf9cN2J in Table 6 on page 18
Corrected by CN J.

(10) rO, 425J on page 19, line 1 of the same page is rO,
Corrected to 450J.

Claims after the separate paper amendment 1) In nickel plating using a plating bath in which nickel ions and sulfur-containing compounds coexist, an amount equivalent to the nickel ions consumed by the plating is added to the composition balance of other plating baths. A nickel plating method characterized by replenishing without damaging the nickel.

2) The method according to claim 1, wherein the nickel ion and the sulfur-containing compound are Ddan nickel.

3) A part of the plating bath solution is circulated through an electrolytic bath for eluting nickel ions using nickel metal as an anode, and the concentration of nickel ions is increased by the nickel ions eluted from the electrode, and then this is recirculated to the plating bath. A method according to claim 1, characterized in that:

4) The anode chamber where the nickel elution anode exists and the cathode chamber where the counter electrode exists are separated by an ion exchange membrane to circulate the plating solution to the anode chamber of the electrolytic cell for nickel elution, and the other cathode chamber contains: 7. The method according to claim 6, wherein the plating bath solution is filled with an electrolyte solution and energized, nickel ions are replenished into the plating bath solution, and the solution with increased nickel ion concentration is returned to the plating bath.

5) Claim 1 in which the electrode base material is nickel plated
The method described in section.

Claims (1)

[Claims] 1) Using a plating bath in which nickel ions and sulfur-containing compounds coexist. 2) In Kel plating, an amount equivalent to the nickel ions consumed by the plating is used to impair the composition balance of other plating baths. A nickel plating method characterized by replenishing without replenishment. 2) The method according to claim 1, wherein the nickel ion and the sulfur-containing compound are rhodan nickel. 3) A part of the plating bath solution is circulated through an electrolytic bath for nickel ion elution using nickel metal as an anode, and the nickel ions eluted from the electrode cause
A method according to claim 1, characterized in that the nickel ions are recycled to the plating bath after enrichment. 4) The anode chamber where the nickel elution anode exists and the cathode chamber where the counter electrode exists are separated by an ion exchange membrane, and the plating solution is circulated to the anode chamber of the electrolytic cell for nickel elution, while the electrolyte solution is circulated in the cathode chamber. 4. The method according to claim 3, wherein the plating bath solution is filled with electricity, nickel ions are replenished into the plating bath solution, and the solution with increased nickel ion concentration is returned to the plating bath. 5) Claim 1 in which the electrode base material is nickel plated
The method described in section.