阅读说明：本技术 微孔镀液及使用了该镀液的对被镀物的微孔镀敷方法 (Micropore plating solution and micropore plating method for plated object using the same ) 是由 柴田佳那 于 2020-03-03 设计创作，主要内容包括：本发明提供一种微孔镀液,其特征在于,含有非导电性粒子和聚合氯化铝,其易于制备带正电的非导电性粒子,稳定性高。此外,利用以在该微孔镀液中镀敷被镀物为特征的对被镀物的微孔镀方法,镀敷中的微孔个数也良好。(The present invention provides a microporous plating solution, which is characterized by containing non-conductive particles and polyaluminium chloride, and by being easy to prepare positively charged non-conductive particles and having high stability. In addition, the plating method for plating a plating object with micropores, which is characterized by plating the plating object with the micropore plating solution, is also excellent in the number of micropores in the plating.)

1. A micro-pore plating solution is characterized in that,

contains non-conductive particles and polyaluminium chloride.

2. The micro-pore plating solution according to claim 1,

the non-conductive particles are at least 1 selected from oxides, nitrides, sulfides and inorganic salts of silicon, barium, zirconium, aluminum and titanium.

3. The micro-pore plating solution of claim 1 or 2, further comprising a surfactant.

4. The micro-pore plating solution according to any one of claims 1 to 3, further comprising a brightener.

5. The microporous plating solution according to any one of claims 1 to 4, which is an electrolytic nickel plating solution.

6. An additive for micro-pore plating, which is characterized in that,

contains non-conductive particles and polyaluminium chloride.

7. An additive kit for micropore plating, which is characterized in that,

each independently comprising the following (a) and (b):

(a) non-conductive particles,

(b) Polyaluminum chloride.

8. A micro-hole plating method for a plated object is characterized in that,

plating the plating object in the microporous plating solution according to any one of claims 1 to 5.

9. A method for controlling the number of plated micro holes,

when an object to be plated is plated in the plating solution for plating a fine pore according to any one of claims 1 to 5, the basicity of the polyaluminum chloride contained in the plating solution for fine pore is changed.

Technical Field

The present invention relates to a plating solution for micropores containing nonconductive particles and a method for plating micropores on a plating object using the plating solution.

Background

Conventionally, chromium plating has been used as decorative plating for automobile parts, faucet fittings (faucets), and the like. However, since the chromium plating is not uniformly precipitated but has holes in the coating, the corrosion current is concentrated at one point only in the case of the chromium plating coating. Thus, multiple layers of nickel are often used with chromium plating to improve corrosion resistance.

The multi-layer nickel is formed by semi-bright nickel plating, high-sulfur nickel impact plating (high-sulfur-content nickel strike plating), bright nickel plating, and micro-porous plating from the bottom, but micro-porous plating is particularly useful for improving corrosion resistance. By providing such a fine-pore plating film, many invisible fine pores can be formed in the chromium plating surface layer, and corrosion resistance can be improved by dispersing corrosion current (patent document 1).

As a technique for forming such micropores in a plating film, a technique of performing electroplating using a plating solution containing non-conductive particles such as silica particles positively charged with aluminum hydroxide is known (patent document 2). In this technique, sodium aluminate (NaAlO) is used as an aluminum compound forming aluminum hydroxide in the plating solution₂) However, a technique of using a sulfate, chloride, or chloride hydrate of aluminum as such an aluminum compound is also known.

However, since the positively charged non-conductive particles are cured when prepared in advance by such a conventional technique, they need to be added separately at the time of use.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. H03-291395

Patent document 2: japanese laid-open patent publication No. H04-371597

Non-patent document

Non-patent document 1: [ prevention of surface Corrosion of microporous chromium plating (Japanese: マイクロポーラスクロムめっき prevention of surface fouling at the periphery of the cell) ], ancient Zhang, practice surface techniques (Japanese: execution surface techniques), Vol.28, No. 11, p522-527, (1981)

Disclosure of Invention

Problems to be solved by the invention

Accordingly, an object of the present invention is to provide a micropore plating solution and a plating method which are easy to prepare positively charged nonconductive particles, have high stability, and are excellent in the number of micropores formed in a plating film.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that the above problems can be solved by using a specific aluminum compound which has not been conventionally used when electrically non-conductive particles are positively charged, and have completed the present invention.

That is, the present invention is a microporous plating solution characterized by containing non-conductive particles and polyaluminum chloride.

The present invention is also an additive for micro-porous plating, characterized by containing non-conductive particles and polyaluminium chloride.

Further, the present invention is an additive kit for micro-hole plating, comprising the following (a) and (b) independently:

(a) non-conductive particles,

(b) Polyaluminum chloride.

The present invention is also a method for plating a plating object with micro-holes, characterized in that the plating object is plated in the micro-hole plating solution.

The present invention is also a method for controlling the number of plated micropores, characterized in that when plating an object to be plated in the micropore plating solution, the basicity of the polyaluminum chloride contained in the micropore plating solution is changed.

Effects of the invention

The micropore plating solution of the present invention is easy to prepare positively charged nonconductive particles, has high stability, and when plated using the micropore plating solution, the number of micropores formed in the plated film is also good.

In addition, the number of plated micropores can be controlled by changing the basicity of the polyaluminum chloride used in the micropore plating solution of the present invention.

Drawings

FIG. 1 is a graph showing the results of test example 1 (left: additive for plating through micropores in reference example 1. right: additive for plating through micropores in example 1).

Fig. 2 is a view showing the shape and the number of pores of an exhaust cathode test piece (brass) used in test example 2.

Fig. 3 is a graph showing the results of the dispersibility test in test example 7.

FIG. 4 is a graph showing the measured values in test example 7.

Fig. 5 is a view showing the shape and the number of micropores of an exhaust cathode test piece (brass) used in test example 8.

Detailed Description

The micro-porous plating solution of the present invention (hereinafter referred to as "plating solution of the present invention") is a plating solution containing non-conductive particles and polyaluminum chloride.

The non-conductive particles used in the plating solution of the present invention are not particularly limited, and examples thereof include oxides, nitrides, sulfides, and inorganic salts of silicon, barium, zirconium, aluminum, and titanium. Among them, oxides such as silicon dioxide (silica) and zirconium dioxide (zirconia), and inorganic salts such as barium sulfate are preferable. More than 1 kind of them can be used. As such non-conductive particles, commercially available products such as MP POWDER 308 and MP POWDER 309A of JCU, for example, can be used. The average particle diameter of the non-conductive particles is not particularly limited, and is, for example, 0.1 to 10 μm, preferably 1.0 to 3.0. mu.m. The average particle diameter is a value measured by an Otsuka Denshi Kabushiki Kaisha ZETA potential/particle diameter/molecular weight measurement System ELSZ-2000.

The content of the non-conductive particles in the plating solution of the present invention is not particularly limited, and is, for example, 0.01 to 10 wt% (hereinafter simply referred to as "%"), preferably 0.05 to 10%.

The polyaluminum chloride used in the plating bath of the present invention is represented by the following formula. The basicity of the polyaluminum chloride is not particularly limited, and is, for example, 50 to 65. The basicity is a value represented by n/6 × 100 (%) in the following formula, and can be calculated from the absorbance by the bicinchoninic acid (bicinchoninic acid) method. In addition, since the number of plated micropores increases when the basicity of the polyaluminum chloride used in the plating solution of the present invention is low and decreases when the basicity is high, the number of micropores can be controlled by appropriately selecting the basicity of the polyaluminum chloride.

[ solution 1]

[Al₂(OH)_nCl_6-n]m

Wherein n is 1 to 5 inclusive and m is 10 or less.

When polyaluminum chloride is contained in the plating solution of the present invention, powdery polyaluminum chloride may be added, or commercially available products of an aqueous solution containing about 10% of alumina, such as Taipac (タイパック, Japan) series, manufactured by DAMING Chemicals, and PAC, manufactured by south sea chemical corporation, may be added. These polyaluminium chlorides may be added as they are or after appropriately diluting them.

The content of the polyaluminum chloride in the plating solution of the present invention is not particularly limited, and is, for example, preferably 0.06 to 50.0%, more preferably 0.06 to 40% in terms of aluminum oxide.

The plating solution of the present invention may contain non-conductive particles and polyaluminum chloride in the plating solution serving as the base solution. The plating solution to be used as the base solution is not particularly limited, and examples thereof include electrolytic nickel plating solutions such as watt baths and sulfamic acid baths, chromium plating solutions of 3 rd valence such as sulfate baths and chloride baths, electroless nickel plating solutions using hypophosphite as a reducing agent, electrolytic tin-nickel alloy plating solutions, electrolytic tin-cobalt alloy plating solutions, and electrolytic nickel-phosphorus alloy plating solutions. Among these baths, an electrolytic nickel plating bath is preferred.

In the plating solution to be the base solution, the specific gravity is preferably 1.0 to 1.6g/cm for maintaining uniform generation of micropores³More preferably 1.1 to 1.4g/cm³The plating solution of (1).

The pH of the plating solution to be the base solution is not particularly limited, but is preferably the same as the pH at the time of plating described later.

From the viewpoint of maintaining dispersibility, it is preferable that the plating solution of the present invention further contains a surfactant. The surfactant is not particularly limited, and examples thereof include nonionic surfactants such as polyethylene glycol, anionic surfactants such as sodium polyoxyethylene alkyl ether sulfate, cationic surfactants such as benzethonium chloride (benzethonium chloride) and octadecyl amine acetate, and amphoteric surfactants such as dodecyl betaine and dodecyl dimethyl amine oxide. These surfactants may be used in an amount of 1 or more. Among these surfactants, a positively charged cationic system or an amphoteric surfactant exhibiting cationic properties in the pH range in use is preferable.

The content of the surfactant in the plating solution of the present invention is not particularly limited, and is, for example, preferably 0.001 to 5%, and more preferably 0.001 to 2%.

In order to adjust the electrochemical potential for the purpose of improving the appearance and preventing rust, it is preferable that the plating solution of the present invention further contains a brightener. The kind of the brightener is not particularly limited, and 1 or 2 or more kinds of brighteners can be appropriately selected from the brighteners suitable for the plating solutions to be the base solutions.

The content of the brightener in the plating solution of the present invention is not particularly limited, and is, for example, preferably 0.01 to 20%, more preferably 0.1 to 15%.

The plating solution of the present invention may further contain a component such as chloral hydrate (chlorohydrate) for the purpose of adjusting the electrochemical potential for rust prevention.

The composition of the watt bath in the plating solution as the base solution may be as follows.

Nickel sulfate (NiSO)₄·6H₂O)：240～300g/L

Nickel chloride (NiCl)₂·6H₂O)：30～45g/L

Boric acid (H)₃BO₃)：30～45g/L

The composition of the sulfamic acid bath may be as follows.

Nickel sulfamate (Ni (SO)₃NH₂)₂·4H₂O)：300～600g/L

Nickel chloride (NiCl)₂·6H₂O)：0～15g/L

Boric acid (H)₃BO₃)：30～40g/L

The electrolytic nickel plating bath such as the watt bath or sulfamic acid bath preferably further contains a primary brightener and a secondary brightener. Examples of the primary brightener include a sulfonamide, a sulfonimide, a benzenesulfonic acid, an alkylsulfonic acid, and the like. As the primary brightnessThe primary brightener is commercially available, for example, as MP333 (manufactured by JCU Co., Ltd.). Examples of the secondary brightener include 1, 4-butynediol and coumarin. The secondary brighteners have the functional groups indicated below (C ═ O, C ≡ C, C ≡ C, C ≡ N, C ≡ N, N-C ≡ S, N ≡ N, -CH ≡ 3838₂-CH-O). The secondary brightener is commercially available, for example, #810 (manufactured by JCU corporation) and the like, and thus can be used. These primary brighteners and secondary brighteners may be used alone or in combination. In addition, the primary brightening agent is preferably added by about 5-15 ml/L, and the secondary brightening agent is preferably added by about 10-35 ml/L.

The composition of the 3-valent chromium plating bath may be as follows.

< sulfate bath >

Basic chromium sulfate (Cr (OH) SO₄)：50～80g/L

Diammonium tartrate ([ CH (OH) COONH)₄]₂)：25～35g/L

Potassium sulfate (K)₂SO₄)：5～150g/L

Ammonium sulfate ((NH)₄)₂SO₄)：5～150g/L

Boric acid (H)₃BO₃)：60～80g/L

Preferably, the 3-valent chromium plating bath such as the sulfate bath further contains a sulfur-containing organic compound. As the sulfur-containing organic compound, saccharin or a salt thereof and a sulfur-containing organic compound having an allyl group are preferably used in combination. Examples of saccharin or a salt thereof include saccharin and sodium saccharin. Examples of the sulfur-containing organic compound having an allyl group include sodium allylsulfonate, allylthiourea, sodium 2-methallylsulfonate, and allyl isothiocyanate. The sulfur-containing organic compound having an allyl group may be used in 1 kind or in combination of 2 kinds, and preferably sodium allylsulfonate or allylthiourea is used individually or in combination. A preferred combination of these sulfur-containing organic compounds is sodium saccharin and sodium allylsulfonate. The content of the sulfur-containing organic compound is, for example, 0.5 to 10g/L, preferably 2 to 8 g/L.

< chloride bath >

Basic chromium sulfate (Cr (OH) SO₄)：50～80g/L

Ammonium formate (HCOONH)₄)：13～22g/L

Potassium chloride (KCl): 5 to 170g/L

Ammonium chloride (NH)₄Cl)：90～100g/L

Ammonium bromide (NH)₄Br)：5.4～6.0g/L

Boric acid (H)₃BO₃)：60～80g/L

The composition of the electroless nickel plating bath may be as follows.

Nickel sulfate (NiSO)₄·6H₂O)：15～30g/L

Sodium phosphinate (NaPH)₂O₂·H₂O)：20～30g/L

Lactic acid (CH)₃CH(OH)COOH)：20～35g/L

Malic acid (HOOCCH (OH) CH₂COOH)：10～20g/L

Citric acid (HOOCCH)₂C(OH)(COOH)CH₂COOH)：10～20g/L

Propionic acid (CH)₃CH₂COOH)：5～10g/L

The composition of the tin-nickel alloy electrolytic plating bath may be as follows.

Nickel chloride (NiCl)₂·6H₂O)：250～300g/L

Tin chloride (SnCl)₂)：40～50g/L

Ammonium chloride (NH)₄Cl)：90～110g/L

Ammonium fluoride (NH)₄F)：55～65g/L

The composition of the tin-cobalt alloy electrolytic plating bath may be as follows.

Cobalt chloride (CoCl)₂)：360～440g/L

Stannous fluoride (SnF)₂)：60～72g/L

Ammonium fluoride (NH)₄F)：25～35g/L

Preferably, the electrolytic tin-cobalt alloy plating bath further contains 5 to 15ml/L of a primary brightener and 10 to 35ml/L of a secondary brightener as described in the above description.

The composition of the nickel-phosphorus alloy electrolytic plating bath may be as follows.

Nickel sulfate (NiSO)₄·6H₂O)：150～200g/L

Sodium chloride (NaCl): 18 to 22g/L

Boric acid (H)₃BO₃)：18～22g/L

Sodium hypophosphite (NaH)₂PO₂·H₂O)：20～30g/L

Orthophosphoric acid (H)₃PO₄)：40～50g/L

Preferably, the nickel-phosphorus alloy electrolytic plating bath further contains 5 to 15ml/L of a primary brightener and 10 to 35ml/L of a secondary brightener as described in the above list.

The method for preparing the plating solution of the present invention is not particularly limited so that the non-conductive particles are positively charged only by including the non-conductive particles and the polyaluminum chloride in the plating solution serving as the base solution, but it is preferable to add and mix an additive for micro-porous plating including the non-conductive particles and the polyaluminum chloride, an additive kit for micro-porous plating including the following (a) and (b) each independently, to the plating solution serving as the base solution.

(a) Non-conductive particles

(b) Polyaluminium chloride

The additive for micro-porous plating containing the non-conductive particles and the polyaluminum chloride may be prepared by adding the non-conductive particles to a part of a plating solution as a base solution, water, or the like, mixing them, and further adding the polyaluminum chloride to the mixture, and mixing them. Such an additive for micro-porous plating is not solidified as compared with the conventional case of using an aluminum compound forming aluminum hydroxide, and therefore can be stored stably and is suitable for replenishment when the non-conductive particles are consumed.

In the additive kit for plating a micropore, each of (a) and (b) may be used as it is or may be diluted with a plating solution or water as a base solution.

In the conventional method of plating a plating object with micropores, the plating solution of the present invention is used in place of the plating solution used for forming micropores, whereby the plating of micropores having a higher number of micropores than in the conventional method can be performed.

The plating material that can be plated by the plating solution of the present invention is not particularly limited as long as it can be plated, and examples thereof include metals such as copper, nickel, and zinc, and resins such as ABS, PC/ABS, and PP. The plating conditions of the plating solution of the present invention may be the same as those of the conventional micropore plating method for an object to be plated, and examples thereof include a temperature of 50 to 55 ℃, a pH of 4.0 to 5.5, and a current density of 3 to 4A/dm²And the like.

Specifically, in order to obtain microporous nickel plating using the plating solution of the present invention, for example, plating may be performed in the order of semi-bright nickel plating, high-sulfur nickel impact plating, and bright nickel plating, then plating may be performed in the plating solution of the present invention using an electrolytic nickel plating solution as a base solution, and finally, chromium plating of 6 or 3 valences may be performed. Further, the trivalent chromium plating may be followed by electrolytic chromate treatment.

The lower layer of the micropore nickel plating is bright nickel plating, high-sulfur nickel impact plating and semi-bright nickel plating. The sulfur content of the bright nickel plating film is preferably 0.05 to 0.15%, the sulfur content of the high-sulfur nickel impact plating film is preferably 0.1 to 0.25%, and the sulfur content of the semi-bright nickel plating film is preferably less than 0.005%.

Preferably, the bright nickel plating film is reduced by about 60 to 200mV relative to the semi-bright nickel plating film, by about 10 to 50mV relative to the high-sulfur nickel impact plating film, and by about 10 to 120mV relative to the microporous nickel plating film. These potential adjustments can be performed by a method such as that described in japanese patent application laid-open No. 5-171468.

The semi-bright nickel plating bath used for obtaining the semi-bright nickel plating film is not particularly limited, and for example, the primary brightener and the secondary brightener described above are preferably added to a known nickel plating bath. As such a semi-bright nickel plating primary brightening agent, CF-NIIA (manufactured by JCU Co., Ltd.) and the like are commercially available, and therefore, the primary brightening agent can be used. Further, as a secondary brightener for semi-bright nickel plating, for example, CF-24T (manufactured by JCU Co., Ltd.) is commercially available, and therefore, the secondary brightener can be used. Preferred semi-bright nickel plating baths include the following ones. The plating conditions are not particularly limited.

< semi-bright nickel plating bath >

The high-sulfur nickel strike plating bath is not particularly limited, and for example, a primary brightener as described in the foregoing list is preferably added to a known nickel plating bath so as to have high sulfur content. As such a primary brightener for high-sulfur nickel impact plating bath, TRI-STRIKE (manufactured by JCU Co., Ltd.) or the like is commercially available, and therefore, the primary brightener can be used. Further, as a preferable high sulfur nickel strike plating bath, the following high sulfur nickel strike plating bath can be mentioned. The plating conditions are not particularly limited.

< high sulfur nickel impact plating bath >

The bright nickel plating bath is not particularly limited as long as it is a nickel plating bath capable of forming a coating film electrochemically lower than the semi-bright nickel plating film, and for example, it is preferable to add the primary brightener and the secondary brightener as described above to a known nickel plating bath. As the primary brightener for bright nickel plating, for example, #83-S, #83 (manufactured by JCU Co., Ltd.) and the like are commercially available, and therefore, the primary brightener can be used. Further, as a secondary brightener for bright nickel plating, there is a secondary brightener which is commercially available, for example, #810 (manufactured by JCU corporation), and therefore, the secondary brightener can be used. As a preferred bright nickel plating bath, the following bright nickel plating bath can be mentioned. The plating conditions are not particularly limited.

< bright nickel plating bath >

As a preferred example of the plating solution of the present invention, the following plating solutions can be mentioned. The plating conditions are not particularly limited, and may be those of conventional micro-porous plating.

< micro-porous nickel plating bath >

As the hexavalent chromium plating bath, a known hexavalent chromium plating bath may be used, and a catalyst is preferably further added. Examples of the catalyst include sodium silicofluoride and strontium silicofluoride. Further, as a hexavalent chromium plating catalyst, for example, ECR-300L (manufactured by JCU corporation) is commercially available, and therefore, the catalyst can be used. As a preferable hexavalent chromium plating bath, the following hexavalent chromium plating bath can be mentioned. The plating conditions are not particularly limited.

Hexavalent chromium plating bath

Chromic anhydride (CrO anhydride) (CrO)₃) 200～250g/L

Sulfuric acid (H)₂SO₄) 0.8～1g/L

5-10 g/L sodium silicofluoride

The trivalent chromium plating bath is not particularly limited, and either a sulfate bath or a chloride bath may be used. As a preferred trivalent chromium plating bath, the following trivalent chromium plating bath can be mentioned. The plating conditions are not particularly limited.

< trivalent chromium plating bath >

Basic chromium sulfate (Cr (OH) SO₄)：50～80g/L

Ammonium formate (HCOONH)₄)：13～22g/L

Potassium chloride (KCl): 5 to 170g/L

Ammonium chloride (NH)₄Cl)：90～100g/L

Ammonium bromide (NH)₄Br)：5.4～6g/L

Boric acid (H)₃BO₃)：60～80g/L

The thus obtained microporous coating film is excellent in corrosion resistance, and therefore suitable for applications such as automobile parts and faucet fittings.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1

Preparation of the additive for micro-pore plating:

a Watt bath having the following composition was prepared, and 50g/L of silica was added thereto, followed by stirring and mixing. Then, polyaluminum chloride (Taipac 6010, basicity 63) was added thereto in an amount of 2g/L in terms of alumina, and the mixture was stirred and mixed to obtain an additive for fine pore plating containing positively charged nonconductive particles.

Watt bath

Nickel sulfate (NiSO)₄·6H₂O)：260g/L

Nickel chloride (NiCl)₂·6H₂O)：45g/L

Boric acid (H)₃BO₃)：45g/L

Specific gravity: 1.200

Comparative example 1

Preparation of the additive for micro-pore plating:

a Watt bath having the same composition as that of the Watt bath used in example 1 was prepared, and 50g/L of silica was added thereto, followed by stirring and mixing. Then, 2g/L in terms of alumina of an aluminum compound which forms aluminum hydroxide was added thereto, and stirred and mixed to obtain an additive for fine pore plating containing charged silica particles.

Test example 1

Dispersibility test:

the additive for micro-porous plating prepared in example 1 and comparative example 1 was added to a glass bottle container, and left for 1 week. As a result of placing the container horizontally, it was confirmed that the additive for micro-hole plating of comparative example 1 was solidified and adhered to the bottom of the container (left part of fig. 1). On the other hand, it was confirmed that the additive for micro-hole plating of example 1 was well dispersed, not solidified, and not adhered to the bottom of the container (right part of fig. 1).

Example 2

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 15ml/L of the micropore plating additive prepared in example 1 to a Watt bath having the following composition.

Watt bath

Nickel sulfate (NiSO)₄·6H₂O)：260g/L

Nickel chloride (NiCl)₂·6H₂O)：45g/L

Boric acid (H)₃BO₃)：45g/L

Brightener #810^＊：3ml/L

Brightener MP333^＊：10ml/L

Bath temperature: 55 deg.C

Specific gravity: 1.205

Manufactured by JCU of Zhao Kabushiki Kaisha

Comparative example 2

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 15ml/L of the additive for micropore plating prepared in comparative example 1 to a Watt bath having the same composition as that of the Watt bath used in example 2.

Test example 2

Manufacturing a micropore plating product:

a microporous plated product was produced by the following procedure using an exhaust cathode test piece (brass, manufactured by Shanghai gold plating test method, Ltd.) having the shape shown in FIG. 2 as a test piece.

(degreasing/acid activation)

The test piece was degreased by treating it with SK-144 (manufactured by JCU Co., Ltd.) for 5 minutes, and then treated with V-345 (manufactured by JCU Co., Ltd.) for 30 seconds, followed by acid activation.

(Bright nickel plating)

The test piece subjected to the degreasing/acid activation treatment by the above-mentioned operation was immersed in a nickel plating solution at a concentration of 4A/dm²Plating was performed for 3 minutes.

< bright nickel plating bath >

Nickel sulfate (NiSO)₄·6H₂O)：260g/L

Nickel chloride (NiCl)₂·6H₂O)：45g/L

Boric acid (H)₃BO₃)：45g/L

Brightener #810^＊：3ml/L

Brightener #83^＊：10ml/L

Manufactured by JCU of Zhao Kabushiki Kaisha

(micro-porous plating)

The test piece subjected to the bright plating was plated in the micro-pore plating solution prepared in example 2 or comparative example 2 at 3A/dm²Plating was performed for 3 minutes.

(chromium plating)

The test piece on which the above-mentioned micro-porous nickel plating was performed was plated in a hexavalent chromium plating solution having the following composition at a concentration of 10A/dm²Plating was performed for 3 minutes.

< hexavalent chromium plating bath >

Chromic anhydride (CrO)₃)：250g/L

Sulfuric acid (H)₂SO₄)：1g/L

Additive ECR 300L: 10ml/L

MISTSHUT (Japanese: ミス Bu (12471); 125 ツ Bu) NP: 0.1ml/L

Manufactured by JCU, Inc

(measurement of the number of micropores 1)

The test piece after the chromium plating was immersed in a copper sulfate plating bath having the following composition for 3 minutes, and thereafter, the immersion time was 0.5A/dm²Plating was performed for 3 minutes.

< copper sulfate plating bath >

Copper sulfate (CuSO)₄·5H₂O)：220g/L

Sulfuric acid (H)₂SO₄)：50g/L

Hydrochloric acid (HCl): 0.15ml/L

(measurement of the number of micropores 2)

After copper sulfate plating, the test piece was gently washed with water and air-dried, and the number of micropores in the plating film was measured. The number of wells was measured on the evaluation surface of the test piece using a microscope VHX-200 manufactured by Keyence. The results of measuring the number of micropores in example 2 and comparative example 2 are shown in table 1.

[ Table 1]

	Example 2	Comparative example 2
			Evaluation of the number of surface pores (number/cm)2)	86800	27604

As is clear from Table 1, even if the equivalent amount of alumina in the plating solution is the same, the more number of micropores can be obtained in the case of example 2 using polyaluminum chloride.

Test example 3

Chronological performance of the additive:

the additive prepared in example 1 was added at 10ml/L to a Watt bath having the same composition as that of the Watt bath used in example 2, and the performance immediately after the preparation and 1 month after the preparation was inferior. Plating was performed in the same manner as in test example 2, and the number of micropores (pieces/cm) was measured in the same manner²). The results are shown in Table 2In (1).

[ Table 2]

	Just after preparation	After 1 month of preparation
			Evaluation of the number of surface pores (number/cm)2)	36805	36381

As is clear from table 2, the number of micropores was approximately constant immediately after the preparation and after 1 month of the preparation. These results show that the additive prepared in example 1 can maintain stable performance also after 1 month.

Example 3

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 1g/L of silica (average particle diameter: 1.5 μm) and 0.04g/L of polyaluminum chloride (Taipac, available from Daminghi chemical Co., Ltd., basicity: 55) in terms of alumina to 267ml of a Watt bath having the same composition as that of the Watt bath used in example 2.

Example 4

Preparing a microporous plating solution:

a microporous plating solution was prepared by adding 1g/L of silica (average particle diameter: 1.5 μm) and 0.04g/L of polyaluminum chloride (Alphaine 83 (Japanese: アルファイソ 83), manufactured by Daminghuai chemical Co., Ltd., basicity 83) in terms of alumina to 267ml of a Watt bath having the same composition as that of the Watt bath used in example 2.

Example 5

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 1g/L of silica (average particle diameter: 1.5 μm) and 0.04g/L of polyaluminum chloride (PAC, south China sea chemical industries, Ltd., basicity: 53) in terms of alumina to 267ml of a Watt bath having the same composition as that of the Watt bath used in example 2.

Example 6

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 1g/L of silica (average particle diameter: 1.5 μm) and 0.04g/L of polyaluminum chloride (Taipac 6010, available from DAMINGCHE CO., LTD., basicity: 63) in terms of alumina to 267ml of a Watt bath having the same composition as that of the Watt bath used in example 2.

Test example 4

Comparison of basicity of polyaluminum chlorides:

a brass plate (Hull Cell plate) having a size of 60cm × 10cm was used as a test piece. The procedure of test example 2 was repeated except that the micropore plating solution prepared in examples 3 to 6 was used as the micropore plating solution, and the current value was set to 2A for the test piece, thereby producing a micropore plated product.

Note that, 6A/dm for Hull Cell plate²、3A/dm²、1A/dm²The number of wells (number/cm) was determined by using a microscope VHX-200 manufactured by Keyence²) The measurement of (1). The results are shown in table 3.

[ Table 3]

As is clear from Table 3, the number of micropores can be controlled by utilizing the difference in basicity even in the same polyaluminum chloride. The basicity suitable for corrosion resistance is 50 to 65.

Example 7

Preparation of the additive for micro-pore plating:

50g/L of silica (average particle diameter: 1.5 μm) was added to a solution having the following composition, followed by stirring and mixing. Then, polyaluminum chloride (Taipac 6010, basicity 63) was added thereto in an amount of 2g/L in terms of alumina, and the mixture was stirred and mixed to obtain an additive for fine pore plating containing positively charged nonconductive particles.

Nickel sulfate (NiSO)₄·6H₂O)：260g/L

Boric acid (H)₃BO₃)：45g/L

Specific gravity: 1.162

Example 8

Preparation of the additive for micro-pore plating:

50g/L of silica (average particle diameter: 1.5 μm) was added to a solution having the following composition, followed by stirring and mixing. Then, polyaluminum chloride (Taipac 6010, basicity 63) was added thereto in an amount of 2g/L in terms of alumina, and the mixture was stirred and mixed to obtain an additive for fine pore plating containing positively charged nonconductive particles.

Nickel chloride (NiCl)₂·6H₂O)：260g/L

Boric acid (H)₃BO₃)：45g/L

Specific gravity: 1.133

Example 9

Preparation of the additive for micro-pore plating:

50g/L of silica (average particle diameter: 1.5 μm) was added to a solution having the following composition, followed by stirring and mixing. Then, polyaluminum chloride (Taipac 6010, basicity 63) was added thereto in an amount of 2g/L in terms of alumina, and the mixture was stirred and mixed to obtain an additive for fine pore plating containing positively charged nonconductive particles.

Nickel sulfate (NiSO)₄·6H₂O)：470g/L

Nickel chloride (NiCl)₂·6H₂O)：35g/L

Boric acid (H)₃BO₃)：40g/L

Specific gravity: 1.280

Example 10

Preparation of the additive for micro-pore plating:

50g/L of silica (average particle diameter: 1.5 μm) was added to a solution having the following composition, followed by stirring and mixing. Then, polyaluminum chloride (Taipac 6010, basicity 63) was added thereto in an amount of 2g/L in terms of alumina, and the mixture was stirred and mixed to obtain an additive for fine pore plating containing positively charged nonconductive particles.

Water: 1L/L

Specific gravity: 1.000

Example 11

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 10ml/L of the additive for micropore plating prepared in example 7 to 1L of the Watt bath having the same composition as that of the Watt bath used in example 2.

Example 12

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 10ml/L of the additive for micropore plating prepared in example 8 to 1L of the Watt bath having the same composition as that of the Watt bath used in example 2.

Example 13

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 10ml/L of the additive for micropore plating prepared in example 9 to 1L of the Watt bath having the same composition as that of the Watt bath used in example 2.

Example 14

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 3mL/L of the additive for micropore plating prepared in example 10 to 267mL of the watt bath having the same composition as that of the watt bath used in example 2.

Example 15

Preparing a microporous plating solution:

a micropore plating solution was prepared by adding 3mL/L of the additive for micropore plating prepared in example 1 to 267mL of the watt bath having the same composition as that of the watt bath used in example 2.

Test example 5

Investigation of the solvent for the additive:

a microporous plated product was produced in the same manner as in test example 2, except that the microporous plating solutions prepared in examples 11 to 13 were used as the microporous plating solutions. Number of micropores (number/cm)²) The measurement was also performed in the same manner as in test example 2. The results are shown in table 4.

[ Table 4]

	Example 11	Example 12	Example 13
				Evaluation of the number of surface pores (number/cm)2)	65012	44063	40468

It was found that the number of micropores varied depending on the solvent of the additive even when the additive amount was the same.

Test example 6

Investigation of the solvent for the additive:

a microporous plated product was produced in the same manner as in test example 4, except that the microporous plating solutions prepared in examples 14 to 15 were used as the microporous plating solutions. Number of micropores (number/cm)²) The measurement was also performed in the same manner as in the test examples. The results are shown in table 5.

[ Table 5]

It was found that the number of micropores varied depending on the solvent of the additive even when the additive amount was the same.

Test example 7

And (3) testing the settleability:

the additive for micro-porous plating prepared in example 1 and examples 7 to 10 was added to a transparent glass container, and left to stand for 1 hour. After the standing, the container was confirmed, and as a result, the additive for micro-porous plating of example 10 was faster in settling of the positively charged non-conductive particles than the other samples. On the other hand, the positively charged non-conductive particles of the additive for micro-hole plating of example 9 settled the slowest (fig. 3).

Next, as shown in fig. 4, the height of the portion where the positively charged nonconductive particles settled was subtracted from the height of the entire solution, and the height of the settled powder was determined. The results are shown in table 6.

[ Table 6]

	Example 1	Example 7	Example 8	Example 9	Example 10
						Measured value (cm)	1.0	1.0	1.0	0.3	2.0

It is understood that the settling rate differs depending on the solvent of the additive.

Example 16

Preparing a microporous plating solution:

1g/L of silica (average particle diameter: 1.5 μm) was added to a Watt bath having the following composition, and the mixture was stirred and mixed. Then, 0.04g/L of polyaluminum chloride (Taipac 6010, basicity 63) in terms of alumina was added thereto, and stirred and mixed to obtain a microporous plating solution containing positively charged nonconductive particles.

Watt bath

Nickel sulfate (NiSO)₄·6H₂O)：260g/L

Nickel chloride (NiCl)₂·6H₂O)：40g/L

Boric acid (H)₃BO₃)：40g/L

Brightener #810^＊：3ml/L

Brightener MP333^＊：10ml/L

Specific gravity: 1.191

Manufactured by JCU of Zhao Kabushiki Kaisha

Example 17

Preparing a microporous plating solution:

1g/L of silica (average particle diameter: 1.5 μm) was added to a Watt bath having the following composition, and the mixture was stirred and mixed. Then, 0.04g/L of polyaluminum chloride (Taipac 6010, basicity 63) in terms of alumina was added thereto, and stirred and mixed to obtain a microporous plating solution containing positively charged nonconductive particles.

Watt bath

Nickel sulfate (NiSO)₄·6H₂O)：300g/L

Nickel chloride (NiCl)₂·6H₂O)：40g/L

Boric acid (H)₃BO₃)：40g/L

Brightener #810^＊：3ml/L

Brightener MP333^＊：10ml/L

Specific gravity: 1.212

Manufactured by JCU of Zhao Kabushiki Kaisha

Example 18

Preparing a microporous plating solution:

1g/L of silica (average particle diameter: 1.5 μm) was added to a Watt bath having the following composition, and the mixture was stirred and mixed. Then, 0.04g/L of polyaluminum chloride (Taipac 6010, basicity 63) in terms of alumina was added thereto, and stirred and mixed to obtain a microporous plating solution containing positively charged nonconductive particles.

Watt bath

Nickel sulfate (NiSO)₄·6H₂O)：350g/L

Nickel chloride (NiCl)₂·6H₂O)：40g/L

Boric acid (H)₃BO₃)：40g/L

Brightener #810^＊：3ml/L

Brightener MP333^＊：10ml/L

Specific gravity: 1.241

Manufactured by JCU of Zhao Kabushiki Kaisha

Example 19

Preparing a microporous plating solution:

1g/L of silica (average particle diameter: 1.5 μm) was added to a Watt bath having the following composition, and the mixture was stirred and mixed. Then, 0.04g/L of polyaluminum chloride (Taipac 6010, basicity 63) in terms of alumina was added thereto, and stirred and mixed to obtain a microporous plating solution containing positively charged nonconductive particles.

Watt bath

Nickel sulfate (NiSO)₄·6H₂O)：400g/L

Nickel chloride (NiCl)₂·6H₂O)：40g/L

Boric acid (H)₃BO₃)：40g/L

Brightener #810^＊：3ml/L

Brightener MP333^＊：10ml/L

Specific gravity: 1.275

Manufactured by JCU of Zhao Kabushiki Kaisha

Test example 8

Confirmation of number of micropores based on watt bath specific gravity:

a microporous plated product was produced in the same manner as in test example 2, except that the microporous plating solutions prepared in examples 16 to 19 were used as the microporous plating solutions. Number of micropores (number/cm)²) The measurement was also performed in the same manner as in the test examples. In this test example, the evaluation surfaces for measuring the number of micropores were the upper surface, the vertical surface, and the lower surface of the exhaust cathode test piece shown in fig. 5. The range width was defined as the value obtained by subtracting the minimum value from the maximum value of the number of micropores in examples 16 to 19. These results are shown in table 7.

[ Table 7]

	Example 16	Example 17	Example 18	Example 19
					Number of micro-holes (per cm) on the upper rack surface2)	78000	29614	32361	17219
Vertical surface micropore count (number/cm)2)	34036	17487	18425	13065
					Number of micropores (number/cm) on lower rack surface2)	36716	22485	17688	13869
Breadth of range (pieces/cm)2)	43964	12127	14673	4154

Table 7 shows that, although there was some fluctuation, the higher the specific gravity of the Watt bath, the smaller the range width, and the less the fluctuation in the number of micropores between the upper and lower surfaces. It is known that, in order to obtain a uniform number of micropores in a complicated shape, it is preferable to increase the specific gravity of the watt bath.

Industrial applicability

From the above, the present invention can be used for manufacturing automobile parts, faucet fittings, and the like.