JPS5814517B2 - Suzmetsukiyokuno Anteikahou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stabilizing acidic electro-tinning baths, which involves adding specific compounds to an aqueous solution or suspension containing stannous ions, an acid, and a brightness additive. The present invention relates to a method for preventing the oxidation of stannous ions, stabilizing free acid, and preventing the generation of sludge.

Acids for acidic electro-tinning baths include sulfuric acid, hydrochloric acid, borofluoric acid,
Inorganic and organic acids such as sulfamic acid, phenolsulfonic acid, toluenesulfonic acid, and benzenesulfonic acid are known, and as gloss additives, dihydroxydiphenylsulfone, N-ethylnaphnalamine, 2,3-butanediol and Reaction products with phenol, polyoxyethylene alkyl amines, polyoxyethylene alkyl ethers, etc. are known.

However, the problem is that the stannous ions in these plating baths are oxidized by oxygen in the air or by electrode reactions, forming sludge as stannic oxides or organic complexes, and the free acid content of the bath changes. Therefore, a more stable electrolytic tin plating bath is desired.

Compounds such as hydrazine and phenolsulfonic acid are known as stabilizing compounds for tin plating baths.

In addition, it has the effect of promoting or suppressing the oxidation of gloss additives.
Polyoxyalkyl amines generally have a better bath stability effect than polyoxyethylene alkyl ethers, and phenyl sulfone compounds generally have better bath stability than these compounds.

The present invention aims to obtain a highly stabilized bath by adding glycocol or containing specific metal ions to an acidic tin plating bath containing a phenyl compound having oxyethylene as a gloss additive.

Acidic tin plating baths are stabilized by using phenolsulfonic acid as the acid, but from the perspective of preventing natural pollution, there is a trend to use less harmful compounds, and organic compounds such as phenol are being used. Fewer baths are desired.

However, when sulfuric acid, for example, is used as the acid, the bath stability of the plating bath is not as good as when phenolsulfonic acid is used.

Amines may exhibit bath stability when added to tinning baths, such as lecithin added to sulfuric acid tin plating baths,
Dicyclohexylamine, enenediamine, morpholine, α-alanine, etc. exhibit bath stabilizing effects.

The effect of amine is not a single effect, but varies greatly depending on the combined effect of acid and brightness additives, but as a result of experiments, acidic tin sulfuric acid containing a phenyl compound with oxyethylene as a brightness agent, including the non-polluting aspect, It became clear that the addition of glycocol was superior in the plating bath.

Glycocor has a weak stabilizing effect in phenolsulfonic acid and toluenesulfonic acid baths.

When hydroxydiphenyl sulfone, for example, is used as a brightness additive in a tin sulfuric acid plating bath, cricocol or aminovaleric acid has a negative effect on bath stability.

Furthermore, when ethoxylated naphtholsulfonic acid is used as a gloss additive in a tin sulfuric acid plating bath, β-alanine, glutamic acid, etc. exhibit negative effects.

In addition, thioglycolic acid and taurine have negative effects,
Glycocor was an excellent stone.

The addition range of glycocol is preferably from 0.1 to 10g/l; outside this range, there is no stabilizing effect or the stability of the bath is impaired.

In the present invention, an acidic electrotinning bath, i.e., an aqueous solution or suspension containing acidic stannous ions in sulfuric acid, contains polyoxyethylene phenylalkylamine as a gloss additive,
Contains an organic compound containing oxyethylene such as ethoxy(polyoxyethylene) naphthol, but the basic bath composition in this case is 5 to 50 i/l of acid as sulfate ion and 10 to 80 g/l of stannous ion. of tin salt, 0
．． It consists of 1 to 30&/l of gloss additive.

As mentioned above, bath stability is improved by adding Glycocol to this basic bath.
A metal ion consisting of chromium, manganese, cobalt, zinc, cadmium, aluminum, and alkaline earth metals
It has been found that the stability of the plating bath can also be improved by containing one or more species in an amount of 0.1 to 100 g/l.

If the amount added is outside this range, there will be no stabilizing effect on the bath, but the stability of the bath will be impaired.

Divalent metal ions generally exhibit a better sludge generation prevention effect than monovalent metal ions.

These metal ions may be added and contained in the form of hydroxides, oxides, or salts.

Examples using a sulfuric acid plating bath are shown in Tables 1 and 2.

From Table 1, it can be seen that the addition of glycocol caused little change in free acid and also greatly reduced the amount of sludge generated.

Table 2 also shows that the amount of sludge generated can be greatly reduced by adding specific metal ions.

Claims (1)

[Scope of Claims] 1. 0.1 to IOg of glycogol is added to a sulfuric acid acidic electro-tinning bath containing a phenyl compound having oxyethylene.
A method for stabilizing a tin plating bath characterized by adding /l. 2. One or more of magnesium, nickel, titanium, vanadine, chromium, manganese, cobalt, zinc, cadmium, aluminum, and alkaline earth metal ions are added to a sulfuric acid acid electrolytic tin plating bath containing a phenyl compound having oxyethylene. A method for stabilizing a tin plating bath characterized by containing 0.1 to 100 g/l.