JP7436071B1 - Non-cyanide brass plating bath and plating method - Google Patents

Abstract

The present invention provides a non-cyan brass plating bath and a plating method that suppresses coloring (reddish) derived from copper and provides stable film uniformity and coverage. [Solution] A non-cyanide brass electroplating bath containing a divalent copper salt, a divalent zinc salt, a hydroxy acid salt, a hydantoin compound, a conductive salt and any of a tin salt, a manganese salt, a cobalt salt, or a nickel salt. and non-cyanide brass electroplating baths containing divalent copper salts, divalent zinc salts, hydroxy acid salts, hydantoin compounds, and any of tin, manganese, cobalt, or nickel salts. A plating method for plating brass on plated objects. [Selection diagram] None

Description

The present invention relates to a non-cyanide brass plating bath and method.

Cyanide has been widely used in plating because it is an excellent complexing agent, but it is harmful to living things and requires strict control to prevent water pollution, air pollution, and worker health. There is a need for a plating solution in the weakly acidic to alkaline range that does not contain .

As a non-cyanide brass plating bath, a non-cyanide brass plating bath mixture containing copper, zinc, metal polyphosphoric acid and orthophosphate, and containing no cyanide (Patent Document 1) is known.

Japanese Patent Application Publication No. 09-217193

The invention of Patent Document 1 is a method of attaching a brass barrier layer on copper foil, and the method lacks gloss, uniformity, coverage, etc. for use as a decoration.

Additionally, in general, when plating is performed using a non-cyanide brass plating bath, there is a problem in that coloring (reddish) originating from copper is unavoidable. In particular, when barrel plating is performed on buttons, fasteners, hooks, and other small parts, reddish plating is mixed in at low current density areas, resulting in noticeable lack of uniformity and coverage. Cannot be used for bathing.

As a result of extensive research into a non-cyanide brass plating bath that suppresses coloring (reddish) derived from copper and provides stable coating uniformity and coverage, the present inventors discovered that hydroxy acid as a complexing agent The present invention has been completed based on the discovery that the above-mentioned problems can be solved by using a salt and a hydantoin compound in combination.

That is, the present invention includes a divalent copper salt, a divalent zinc salt, a hydroxy acid salt, a hydantoin compound, and a conductive salt , and further includes a tin salt, a manganese salt, a cobalt salt, or a nickel salt. This is a non-cyanide copper-zinc alloy electroplating bath.

Further, the present invention is characterized in that the hydroxy acid salt is a hydroxy acid having 2 or 4 carbon atoms, and the hydantoin compound is hydantoin, alkylhydantoin, or phenylhydantoin.

Further, the present invention includes a divalent copper salt, a divalent zinc salt, a hydroxy acid salt, a hydantoin compound, and a conductive salt , and further includes a non-containing salt containing any one of a tin salt, a manganese salt, a cobalt salt, or a nickel salt. This is a plating method characterized by plating a copper -zinc alloy onto an object to be plated using a cyan copper-zinc alloy electroplating bath.

According to the present invention, stable uniformity and coverage can be obtained even in barrel plating by adjusting the ratio of tin salt, manganese salt, cobalt salt, or nickel salt in addition to hydroxy acid salts and hydantoin compounds. Cyan brass plating bath can be provided.

Furthermore, the non-cyanide brass plating bath of the present invention provides stable uniformity and coverage not only in rack plating but also in barrel plating, making it suitable for plating when manufacturing decorative plated objects. Can be done.

In addition, the non-cyanide brass plating bath of the present invention provides stable uniformity and coverage, so plating can be performed at a bath temperature as low as about 40°C, which not only improves the appearance of the plating film but also improves the appearance of the plating film. , it is also possible to obtain the effect of improving workability.

Furthermore, by adding a conductive salt to the plating bath, further uniformity and coverage can be obtained, and the current density range can be expanded.

The present invention provides a non-cyanide salt containing a divalent zinc salt, a divalent copper salt, a hydroxy acid salt, a hydantoin compound, a conductive salt and any one of a tin salt, a manganese salt, a cobalt salt or a nickel salt. Brass electroplating bath.

In the present invention, both hydroxy acid salts and hydantoin compounds are used as complexing agents.

Examples of hydroxy acid salts include hydroxy acid salts having 2 or 4 carbon atoms, such as gluconate, tartrate, citrate, malate, among others, tartrate, citric acid, etc. Salt is preferred.

Examples of the salts of hydroxy acids include alkali metal salts and alkaline earth metal salts of hydroxy acids, such as potassium salts, sodium salts, and calcium salts. The above-mentioned hydroxy acid salts may be blended alone or in combination of two or more.

The hydroxy acid salt is preferably contained in the plating bath in an amount of 50 to 400 g/L, particularly preferably 100 to 300 g/L.

Examples of hydantoin compounds include hydantoin, alkylhydantoin such as 1-methylhydantoin, 5-ethylhydantoin or 5,5-dimethylhydantoin, 5-phenylhydantoin, and hydantoin and alkylhydantoin are preferred, with hydantoin, 5, 5-dimethylhydantoin is preferred. The above-mentioned hydantoin compounds may be blended alone or in combination of two or more.

The hydantoin compound is preferably contained in the plating bath in an amount of 10 to 150 g/L, more preferably 10 to 150 g/L.

In the plating bath of the present invention, the hydroxy acid salt and the hydantoin compound are used in a weight ratio of 0.15 to 0.6 part by weight per 1 part by weight of the hydroxy acid salt. is preferred.

Examples of divalent copper salts include salts of divalent copper and inorganic or organic acids, such as cuprous sulfate, cuprous pyrophosphate, cuprous oxalate, cuprous oxide, and cuprous chloride. Examples include copper. In the plating bath of the present invention, even divalent copper oxides, chlorides, etc. can be used. The divalent copper salts mentioned above may be blended alone or in combination of two or more.

The divalent copper salt is preferably contained in the plating bath in an amount of 1 to 30 g/L, more preferably 3 to 15 g/L.

Examples of divalent zinc salts include salts of divalent zinc and inorganic or organic acids, such as zinc sulfate, zinc acetate, zinc hydroxide, zinc oxide, and zinc chloride. In the plating bath of the present invention, even divalent zinc oxides, chlorides, etc. can be used. The divalent zinc salts mentioned above may be blended alone or in combination of two or more.

The divalent zinc salt is preferably contained in the plating bath in an amount of 1 to 30 g/L, more preferably 1.5 to 7.0 g/L.

In order to obtain a brass-colored plating film, the weight ratio of metallic copper and metallic zinc in the plating bath is important, and the ratio of metallic zinc to 1 part by weight of metallic copper is in the range of 0.3 to 0.9 parts by weight. It is preferable to use a divalent zinc salt and a divalent copper salt, as shown in .

In the present invention, by adding any one of tin salt, manganese salt, cobalt salt, and nickel salt to the plating bath, the plating metal becomes a ternary alloy and the glossiness is increased. Examples of such metal salts include salts of tin, manganese, cobalt, nickel, and alkali metals, alkaline earth metals, inorganic acids, or organic acids, such as sodium stannate, manganese sulfate, cobalt sulfate, Examples include nickel sulfate.

The metal salt is preferably contained in the plating bath in an amount of 0.1 to 2 g/L.

In the plating bath of the present invention, by further adding a conductive salt, the uniformity and coverage of the plating film are improved and the current density range is widened, so that more favorable results can be obtained.

As the conductive salt, chlorides of alkali metals, alkaline earth metals, or ammonia are preferable, and specific examples thereof include potassium chloride, sodium chloride, calcium chloride, and ammonium chloride. The divalent copper salts mentioned above may be blended alone or in combination of two or more.

The conductive salt is preferably contained in the plating bath in an amount of 5 to 50 g/L.

The non-cyanide brass plating bath of the present invention includes any of the above-mentioned divalent copper salts, divalent zinc salts, hydroxy acid salts, hydantoin compounds, conductive salts, tin salts, manganese salts, cobalt salts, or nickel salts. can be produced by dissolving it in water.

The present invention provides a non-cyanide brass electroplating bath containing a divalent copper salt, a divalent zinc salt, a hydroxy acid salt, a hydantoin compound, a conductive salt and any of a tin salt, a manganese salt, a cobalt salt, or a nickel salt. This is a plating method that uses brass to plate the object to be plated.

Plating may be carried out using conventional electroplating methods, such as pretreatment of the object to be plated by degreasing, washing, acid immersion, electrolytic degreasing, acid activation, etc., and then plating by a method such as a rack method or a barrel method. be able to. For example, when using the rack method, the bath temperature is 30 to 50°C, the current is 0.2 to 2.0 A/dm ² and the plating time is 0.5 to 3 minutes, and when the barrel method is used, the current is 5 to 10 A/kg, and the plating time is 0.5 to 3 minutes. This can be carried out by plating for 5 to 15 minutes and at a rotational speed of 4 to 15 revolutions/minute.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
Potassium sodium tartrate 150.0g/L, hydantoin 30.0g/L, copper(II) sulfate pentahydrate 5.0g/L, zinc(II) sulfate heptahydrate 3.0g/L, sodium chloride A 10 L plating bath was prepared using 20.0 g/L and 0.5 g/L of sodium (IV) stannate trihydrate.

250 copper-plated zinc die castings (3.2 g/piece) were subjected to alkaline electrolytic degreasing using 50.0 g/L of activator Cu (product name: Shimizu Co., Ltd.), followed by water washing, acid washing, and pretreatment for water washing. After that, plating was performed in a mini-barrel (mini-barrel made by Kondo) under the following conditions.

Plating conditions Anode = 2 carbon plates (100cm x 100cm x 1cm) Current value = 7A/Kg, Current time = 10 minutes, Bath temperature = 40°C
Barrel rotation speed = 6 revolutions per minute Plating thickness = approx. 0.4m
After plating, the object to be plated was immediately taken out of the barrel, washed with water, and dried in a centrifugal dryer.

Evaluation method Color:
Using a color difference meter (CM-3500d, manufactured by Konica Minolta, Inc.), measure the L value, a value, and b value SCI (including specular reflection light) of the flat part of the object to be plated (n = 10), and calculate the average value. was calculated as ΔE with respect to the cyan-based brass plating. The lower the value, the closer the color is to a cyan-based brass color.
The cyan-based brass plated product is obtained by plating 250 copper-plated zinc die castings (3.2 g/piece) with "Brass Salt" (trade name, manufactured by Nihon Kagaku Sangyo Co., Ltd.) under the following plating conditions. was used.
Plating conditions Anode = 2 brass plates (100cm x 100cm x 0.5mm) Current value = 5A/Kg, Current time = 10 minutes, Bath temperature = 40℃
Barrel rotation speed = 6 revolutions per minute

Coverage uniformity:
Measured with a color difference meter (n = 100), and calculated ΔE from the average value using the individual L value, a value, and b value from the average of the L value, a value, and b value of all samples to be plated. . The standard deviation was calculated using the calculated ΔE of n=100, and the coverage and uniformity were evaluated. The lower the standard deviation value, the better the coverage and uniformity of the finish.
◎: Standard deviation is 0.3 or less ○: Standard deviation is more than 0.3 to less than 0.7 △: Standard deviation is 0.7 or more

Glossiness:
Measurements were similarly made using a color difference meter (n=10), and the average value of the L values was used for evaluation. The higher the average L value, the more glossy the finish.
◎: Average L value is 83.5 or more ○: Average L value is less than 83.5 to over 82.4 △: Average L value is 82.4 or less

Examples 2 to 9
Plating was carried out in the same manner as in Example 1, except that the plating baths shown in Tables 1 and 2 were used.
In Examples 2 to 9, 5.0 g/L of copper (II) sulfate pentahydrate was used as the divalent copper salt, and 3.0 g/L of zinc (II) sulfate heptahydrate was used as the divalent zinc salt. 0 g/L and 20.0 g/L of sodium chloride as a conductive salt were added to the plating bath.

Comparative examples 1 and 2
Plating was carried out in the same manner as in Example 1, except that the plating shown in Table 3 was used.
In Comparative Examples 1 and 2, copper (II) sulfate pentahydrate was used as the divalent copper salt at 5.0 g/L, and zinc (II) sulfate heptahydrate was used as the divalent zinc salt at 3.0 g/L. 0 g/L and 20.0 g/L of sodium chloride as a conductive salt were added to the plating bath.
The results are shown in Tables 1 to 4.

Results and Discussion As can be seen from Tables 1 to 4, in the plating bath containing hydroxy acid, hydantoin compound, and photoselector, the ΔE value based on the cyan brass color was low, and the coverage and uniformity of the cyan brass color standard was also low. Although results similar to or similar to those of brass plating were obtained, in the comparative example, the ΔE value also increased, the color became more reddish than the brass color, and the coverage and uniformity were also deteriorated.

Claims (3)

A non-cyanide product characterized by containing a divalent copper salt, a divalent zinc salt, a hydroxy acid salt, a hydantoin compound, and a conductive salt, and further containing any one of a tin salt, a manganese salt, a cobalt salt, or a nickel salt. Copper-zinc alloy electroplating bath. The non-cyanide copper-zinc alloy according to claim 1, wherein the hydroxy acid salt is a hydroxy acid salt having 2 or 4 carbon atoms, and the hydantoin compound is hydantoin, alkylhydantoin or phenylhydantoin. Electroplating bath. Non-cyanide copper-zinc alloy electrical containing divalent copper salts, divalent zinc salts, hydroxy acid salts, hydantoin compounds, and conductive salts , and further containing any of tin salts, manganese salts, cobalt salts, or nickel salts. A plating method characterized by plating a copper-zinc alloy onto an object to be plated using a plating bath.