DE1496919C3 - Aqueous galvanic nickel bath - Google Patents

Description

N-CH ₂ -C = CH

wherein R is a hydroxyalkyl group and a is an integer from 1 to 4, has

2. Bath according to claim 1, characterized in that the primary brightener in an amount of 0.005 g / L to 0.10 g / L is present

3. Bath according to claim 1 or 2, characterized in that there is also a secondary Contains auxiliary brighteners

4. Bath according to claim 1, 2 or 3, characterized in that it is also an anionic Contains wetting agents

The invention relates to an aqueous galvanic nickel bath containing a soluble nickel salt, a secondary one Brightener and, as the primary brightener, an N-propargylpyridinium halide substituted on the heterocycle contains

Such a bath is known from DE-AS 10 66 068. As secondary brighteners are used in this known bath sulfoxy compounds used, such as. B. benzenesulfonamide and naphthalenetrisulfonic acid. the N-propargylpyridinium halides used as primary brighteners can on the carbon atoms of the pyridine nucleus methyl and ethyl groups and / or Contain halogen atoms and / or sulfonic acid groups.

In contrast, it was found that such N-propargylpyridinium halide are particularly valuable brighteners that are attached to the carbon atoms of the Pyridine nucleus have one or more hydroxyalkyl groups. Another advantage is that making such connections with relative ease Iassea

Accordingly, the invention relates to an aqueous galvanic bath of the type specified in the introduction which is characterized in that the N-propargylpyridinium halide is a cation of the structure

(R) ₀

N-CH ₂ -C =

wherein R is a hydroxyalkyl group and a is an integer from 1 to 4, has

Advantageous further developments of the invention are described in claims 2-4.

The additives which can be used as brighteners in galvanic nickel baths are generally due to Their predominant function is divided into two classes Primary brighteners are materials that are in very low or relatively low concentration, typically 0.002 to 0.2 g / L can be used and who may or may not have a visible gloss effect themselves. These primary brighteners, which, when used alone, can show a certain gloss effect, generally have also disadvantageous side effects such as reduced current efficiency, poor deposit color, brittleness deposition and flaking and very narrow areas of gloss deposition. Secondary brighteners are materials that are commonly used in combination with primary brighteners, but in considerably higher concentration than the primary brighteners, typically 1 g / L to 30 g / L these Materials themselves can produce a certain gloss effect or grain refinement, the deposits however, are usually not mirror-finish and the speed of glossing is generally insufficient.

In the ideal case, it is a combination of primary and secondary brighteners with correctly selected and Compatible nature possible, quickly ductile, leveled deposits over a wide range of current density to achieve.

Examples of groups R in the primary brightener used according to the invention are hydroxymethyl / 3-hydroxyethyl and γ-hydroxypropyl

Typical compounds of this class are the following:

Table I.

Primary brighteners

A. 2 - /? - Hydroxyethyl-N-propargylpyridinium bromide

B. 2-y-hydroxypropyl-N-propargylpyridinium bromide ί

C. 3-Hydroxymethyl-N-propargylpyridinium bromide!

D. 2,4,6-trihydroxymethyl-N-propargylpyridinium- i bromide;

The primary brighteners of the present invention can be used in concentrations from 0.005 g / l to 0.10 g / l can be used, whereby the particular j selected concentration depends on the particular species and j the concentration of the secondary brighteners and secondary auxiliary brighteners used and also of | such characteristics as the concentration of nickel; sulphate nickel chloride and boric acid, the operating conditions with regard to temperature and degree of movement, the desired degree of gloss, gloss speed and leveling and the polishing of the base metal In particular, 0.01 g / L to 0.05 g / L is used

Secondary brighteners (which are typically in an amount from 1 g / l to 75 g / l, preferably 1 g / l to 20 g / l), which in combination with the primary Brighteners that are useful are generally aromatic sulfonates, sulfonamides, or sulfimides, too which may include such substituted aromatic compounds, such as 13, Q-naphthalene trisulfonate sodium or potassium salts of saccharin, sodium or potassium salts of o-sulfobenzaldehyde, benzenesulfonamide, Benzene monosulfonate and the like. A preferred secondary brightener for use in Nickel plating baths of the high chlorine type can contain a sodium or potassium salt of sulfonated Dibenzothiophene dioxide, which is obtained by sulfonating diphenyl with fuming sulfuric acid (20% oleum) for about 2 st, isolating the reaction product and

Neutralization is established.It is believed that the predominant reaction product is the compound which contains 3 sulfonic acid groups, along with some mono- and disubstituted components. The secondary Brighteners are generally characterized in that they have at least one sulfone group or Sulfonic acid group bonded to a core carbon atom of a homocyclic aromatic ring.

Secondary auxiliary brighteners, such as sodium 2-propene-1-sulfonate, Sodium 3-chloro-2-butene-1-sulfonate, mixed isomers of sodium 2-butene-2-hydroxy-1-sulfonate and sodium 2-butene-1-hydroxy-2-sulfonate made by reacting butadiene monoxide with Sodium sulfite, or phenylpropiolamide, can be used in conjunction with the secondary brightener or the secondary brighteners can be used.

Usual baths and processes for the galvanic deposition of bright nickel are in »Principles of Electroplating and Electroforming «, Blum and Hogaboom, pages 362 to 381, revised 3rd edition, 1949, McGraw-Hill Book Co, Ine, New York, and in “Modem Electroplating «, edited by A.G. Gray, The Electrochemical Society (1953), 299-355, described. The control and operating conditions, including concentration of bath components, pH, Temperature, cathode current density and the like, of these conventional baths are usually on the present invention applicable. Practically all baths contain the galvanic deposition of glossy niches Nickel sulfate, a chloride, usually nickel chloride, a buffering agent, usually boric acid, and a Wetting agents. Such baths include the well-known Watts baths and the high chloride baths. Other baths can use a combination of nickel fluorate with nickel sulfate and nickel chloride as a source of nickel or contain a combination of nickel sulfamate and nickel chloride. Typical bathrooms from Watts-type and high chloride baths are given in Tables II and III.

Table II

Watts-type baths

Nickel sulfate

Nickel chloride

Boric acid

temperature

Move

200 g / l to 400 g / l
30 g / l to 75 g / l
30 g / l to 50 g / l
38 ° C to 65 ° C
mechanical and / or
Air or pumps the
Solution and the like
2.5 to 4.5,
electrometric

Table III

Baths with high chloride content

Nickel chloride

Nickel sulfate

Boric acid

temperature

Move

150 g / l to 300 g / l
40 g / l to 150 g / l
30 g / l to 50 g / l
38 ° C to 65 ° C
mechanical and / or
Air or pumps the
solution
2.5 to 4.5,
electrometric

thin film is depleted of cations immediately at the cathode. This is expediently done by Moving, for example by stirring with air, pumping the solution around, moving the cathode rod and the like.

The following examples serve to explain the invention in more detail. In each of the examples there was a Aqueous acidic nickel-containing bath prepared with the specified components. The deposition of Nickel was carried out by passing electrical current through an electrical circuit, which contained a nickel anode and a sheet metal cathode. The baths were moved, usually by one moving cathode. Bright nickel was obtained in all of the experiments given here.

In Examples 1 to 4, the following standard bath was used as the basic solution:

Nickel sulfate

Nickel chloride

Boric acid

300 g / l
60 g / l
45 g / l

The primary brighteners are listed in Table I given earlier

Secondary brighteners used in the following examples are shown in Table IV specified.

Table IV

Secondary brighteners

N. O-Benzoic acid sulfimide (Na-Salz)

O. Dibenzenesulfonamide

P. N, N'-bis (phenylsulfonyl) -4,4'-diphenyl-

disulfonamide
Q. sulfonated dibenzothiophene dioxide.

Secondary auxiliary brighteners used in the following examples are shown in Table V. listed.

Table V

Secondary auxiliary brighteners

R. Sodium 3-chloro-2-butene-1-sulfonate
S. Sodium allyl sulfonate

The wetting agents used in the following examples are listed in Table VI

Table VI

Wetting agents

T. Sodium Lauryl Sulphate

U. Sodium di-n-hexyl sulfosuccinate

Table VII

example
No.

additive

lot
g / l

Current temperature density

A / dm ^{2 0} C

The best results are usually achieved by taking steps to prevent the

A. 0.020 N 2.0 R. 3.0 T 0.01 B. 0.020 O 2.0 R. 3.0 T 0.01

60

60

continuation

example
No.

additive

lot

g / l

C. 0.020 P. 2.0 R. 3.0 T 0.01 D. 0.020 Q 2.0 S. 3.0 U 0.01

Current density

A / dm ²

temperature

60

The primary brighteners used according to the invention can be prepared by that

an appropriately substituted pyridine is reacted with a propargyl halide in a manner known per se

The compound 2-γ-hydroxypropyl-N-propargylpyridinium bromide can be made, for example, as follows:

10 g of 2-γ-hydroxypropyl pyridine, 20 ml of propargyl bromide and 25 ml of dimethylformamide are left to stand at room temperature I6V2 st, and then are 25 ml of acetone were added. The crystalline precipitate is filtered off, washed with acetone and in the air dried The product weighs 16.7 g (94% yield). Mp = 137-138 ° C.

The presence of a hydroxyalkyl group in the pyridine nucleus appears to favor this reaction, since corresponding compounds with other substituents on the pyridine nucleus, such as. B. with alkyl groups, the Make starting material for the mentioned reaction less accessible.

Claims (1)

Patent claims: 1. Aqueous galvanic nickel bath containing a soluble nickel salt, a secondary brightener and contains an N-propargylpyridinium halide substituted on the heterocycle as the primary brightener, characterized in that the N-propargylpyridinium halide is a cation of structure