DE1003531B - Acid galvanic bright nickel plating bath - Google Patents

Description

The invention relates to the galvanic production of nickel coatings in an aqueous, acidic bath. It was encouraged to create pliable or tough nickel layers with a bright, shiny appearance in aqueous, acidic nickel plating baths to be generated by having such baths with coumarin, its alkyl or acyl derivatives does not add more than 4 carbon atoms or their halogen, hydroxy or carboxy derivatives. In such However, such additives have certain disadvantages in aqueous, acidic nickel plating baths. For example, this is how in the bath oily products, which cause streaks and tuft scars in the coating and relatively quickly build up deposits on the cathode, which can only be achieved by treating the Bath or the like can be removed periodically.

Surprisingly, however, it has been shown that these disadvantages can be eliminated and a fine-grained, Shiny nickel coating can be obtained in aqueous, acidic nickel baths if you according to the invention add certain monoalkoxycoumarins to such baths.

According to the invention, a nickel plating bath contains an aqueous, acidic nickel-containing solution with a Alkoxycoumarin of the structure:

Acid Galvanic
Bright nickel plating bath

CH

in which R is a methyl or ethyl group.

The presence of these alkoxy coumarins in the bath causes the electroplated layer in spite of one cloudy and milky appearance becomes very fine-grained and becomes remarkable as the electroplating progresses shows increasing gloss. Compared to other substituted coumarins, e.g. B. Hydroxycoumarins, such as 7-hydroxycoumarin (umbelliferone), or for this purpose with carboxy, chloro or methyl groups substituted coumarins show the 6-, 7- or 8-monomethoxy or monoethoxycoumarins (which are easier to represent than the substituents in the 5-position), provided they are used alone and especially in warm, acidic nickel baths according to Watt or similar are used, one exceptional and one with increasing Thickness of the nickel plating noticeably increasing gloss.

These coumarins substituted by methoxy and ethoxy groups represent an improvement over this the pure coumarins. In particular, the 6-, 7- or 8-monomethoxy or monoethoxy coumarins are called in nickel baths from 60 to 80 ° C even in concentrations of more than about 1 g / l no oily effects (the in the nickel coating in stripes and tuft scars Applicant:

The Udylite Research Corporation,
Detroit, me. (V. St. A.)

Representative: Dr.-Ing. H. Negendank, patent attorney,
Hamburg 36, Neuer Wall 43

Claimed priority:
V. St. v. America April 5, 1954

Henry Brown, Oakland, Mich. (V. St. Α.),
has been named as the inventor

express). The reduction product of the cathode formed in the bath during electroplating is adversely affected in the case of the bath additives according to the invention, the nickel coating is far less than that in baths occurs with coumarins or with the coumarin derivatives proposed so far. Therefore, the invention requires Nickel plating bath with alkoxycoumarins is a less common treatment with carbon and supplies

a glossier coating.

The appropriate concentration of methoxy and ethoxy coumarins is of any concentration on up to saturation not critical; these substances can be used in concentrations from about 0.05 to about 2 g / l can be used; the concentration is preferably 0.1 to 1 g / l.

It was also found that adding the compounds known _{per se for electroplating baths, which contain unsaturated methylene sulfone groups (= C - SO 2} -), in particular benzenesulfonic acids, benzenesulfonamides and benzenesulfonimides, to the baths according to the invention results in a high-gloss, smooth nickel coating with good ductility ; o-Benzoylsulfonimide (saccharin) has proven to be particularly suitable here. The sole presence of the alkoxy coumarins according to the invention or only the presence of a compound with an unsaturated methylene sulfone group does not yet give any clear indication of the remarkable, different and more favorable result; this only occurs when both

Substances are present at the same time. The superiority of such baths in terms of better shine and faster Gloss formation is particularly pronounced and noticeable in comparison to baths with chloro-, methyl-, hydroxy- or carboxy-substituted coumarins or just coumarin.

609 837/391

While the simpler arylsulfonamides and some of the arylsulfonic acids have a shiny and mirror-like appearance However, it is, for example, to produce precipitation on polished metals such as polished brass Steel polished with very fine emery or at 5 a tamped (but unfired) copper layer 0.08 to 0.01 mm thick is not possible to achieve a good one Obtain nickel plating; in these cases a layer with a dull and gray appearance is obtained. if however, one of these alkoxy coumarins together with a substance that contains the unsaturated methylene sulfone group, is used, one can even create a shiny, reflective deposit on a tamped copper deposit reach.

The aryl sulfones, sulfonamides, sulfonimides and sulfonic acids generally do not have a critical concentration range in the bath and practically generate after No further improvement when reaching their optimum concentration. The practically usable concentrations range from 0.05 g / l to saturation.

The baths according to the invention can be operated at pn values in the range from 2 to 5.5 and at temperatures in the range from 20 to 70 ° C. and even higher; the preferred range for the current density is between 5 and 160 mA / cm ² , these values depending on the movement of the bath liquid, its temperature and its concentration and the type of nickel salt. The methoxy and ethoxy coumarins according to the invention work better at higher ρπ values of the nickel bath, ie between 3 and 5.5, and the most favorable working range was found to be between 4.2 and 4.5. One of the main advantages of these methoxy and Äthoxycumarine is compared with known baths at high p _H values, which is usually required between 4 and 4.5, in their ability in the lower p-value range 3-3 5 to be able to work. With these lower pn values, the precipitation of iron hydroxide [iron (III) oxide hydrate] is avoided, whereas this causes rough and pitted surfaces in baths with a higher pH value if a high filtration speed is not maintained. It is generally preferred to use a Watt nickel plating bath as an entry or initial bath. Typical examples of the aryl sulfones with the associated concentrations are compiled in the table; they can be used satisfactorily in connection with alkoxycoumarins according to the invention, the latter being used at an optimum concentration between 0.1 and 2 g / l.

The following are examples of specific baths and associated working conditions, which are suitable embodiments of the invention.

Example I.

NiCl ₂ . 6H ₂ O 100.0 g / L

H ₃ BO ₃ 45.0 to 50.0 g / l

8-methoxycoumarin 0.1 to 0.6 g / l

PH 3.8 to 4.8

Temperature 60 ° C

Example II

NiCl ₂ · 6H ₂ O 150.0 g / l

NiSO ₄ · 6H ₂ O 150.0 g / l

H ₃ BO ₃ 40.0 g / l

Ni (BF ₄ ) ₂ 1.0 to 6.0 g / l

7-methoxycoumarin 0.3 to 2.0 g / l

o-Benzoylsulfonimide 0.1 to 0.5 g / l

Benzenesulfonamide 0.1 to 2.0 g / l

PH 3.0 to 4.5

Example III

NiSO ₄ - 6H ₂ O 200.0 to 300.0 g / l

NiCl ₂ 40.0 to 75.0 g / l

H ₃ BO ₃ 40.0 g / l

Ni (BF ₄ ) ₂ 1.0 to 4.0 g / l

8-methoxycoumarin 0.3 to 1.5 g / l

o-benzoylsulfonimide,. 0.1 to 0.3 g / l

PH 4.0 to 4.5

Tabel

best

Benzenesulfonamide 0.1

Toluenesulfonamide 0.1

o-Benzoylsulfonimide 0.1

N-Benzoylbenzenesulfonimide 0.1

p-toluenesulfonchloramide 0.1

p-bromobenzenesulfonamide 0.1

6-chloro-o-benzoylsulfonimide 0.1

m-aldehyde benzenesulfonamide 0.1

Sulfomethylbenzenesulfonamide 0.1

Benzenesulfonamide-m-carboxylamide .. 0.1

7-aldehydo-o-benzoylsulfonimide .... 0.1

N-acetylbenzenesulfonimide 0.1

Methoxybenzenesulfonamide 0.1

Hydroxybenzenesulfonamide ......... 0.1

p-Carboxylamide benzenesulfonamide ... 0.1

p-chlorobenzenesulfonamide 0.1

Benzene mono-, di- or tri-sulfonic acid 1.0

concentration 3.0 g / i 2.0 until 2.0 until 1.0 until 1.0 until 1.0 until 1.0 until 1.0 until 6.0 until 3.0 until 3.0 until 2.0 until 1.0 until 2.0 until 3.0 until 3.0 until 10.0 until until

50

55

60

⁵ 5

70

Example IV

NiCl ₂ - 6H ₂ O 100.0 g / l

H ₃ BO ₃ 40, OgA

8-ethoxycoumarin 0.3 to 1.0 g / l

Benzenesulfonamide 1.0 to 2.0 g / l

Example V

MSO ₄ · 6H ₂ O 200.0 to 300.0 g / L

NiCl ₂ -OH ₂ O 40.0 to 75.0 g / l

H ₃ BO ₃ 40.0 g / l

8-ethoxycoumarin 0.3 to 1.0 g / l

o-Benzoylsulfonimide 0.1 to 1.0 g / l

Exceptionally favorable results are achieved by Examples II, III, V, in which one has fully glossy, ductile, evenly thick nickel layers obtained with the previously known coumarin derivatives and the Coumarin itself, when combined alone in conjunction with the = C-S Og group, cannot be achieved are. The superiority lies not only in the fact that a glossier coating, and that at a high electroplating speed, is achieved, but also in the wider current density range, within which the electroplating speed is superior, and in the fact that an active carbon bath treatment is less is often required.

Claims (6)

PATENT CLAIMS: 1. Acid galvanic bright nickel plating bath, thereby characterized as being an alkoxy coumarin with the structure RO-- contains, in which R represents a methyl or ethyl group. 2. Bath according to claim 1, characterized in that the alkoxy coumarin is a 6-, 7- or 8-methoxy or ethoxy coumarin. 3. Bath according to claim 1 and 2, characterized in that that alkoxycoumarin in a concentration of 0.05 to 2 g / l, preferably from 0.1 to 1 g / l, is available. 4. Bath according to claim 1 to 3, characterized in that in a known manner in the bath in addition to the alkoxy coumarin, a compound is contained which contains the unsaturated methylene sulfone-I I. group = C - SO ₂ preferably contains benzenesulfonic acid, benzenesulfonamide, benzenesulfonimide or saccharin, the sulfone compounds mentioned are preferably present in a concentration between 0.05 g / l and saturation. 5. Bath according to claim 1 to 4, characterized in that it is nickel sulfate as the starting solution and / or contains nickel chloride. 6. Bath according to claim 1 to 5, characterized in that the pn value of the bath is between 3 to 5.5, preferably between 4.2 and 4.5. Considered publications: U.S. Patents Nos. 2,195,409, 2,427,280,
644 789; French Patent No. 998185;
German patent specification No. 900 037. © 609 837/391 2.57