DE900037C - Electroplated nickel plating - Google Patents

Description

(WiGBl. P. 175)

ISSUED DECEMBER 17, 1953

Ui284VIa / 48a

The invention relates to improvements in the practice of galvanic nickel plating with the help of aqueous acidic baths. The invention particularly relates to the use of certain Agent additives for the purpose of reducing the grain size and luster of the nickel plating or to increase the nickel deposit; the invention is particularly concerned with manufacture of galvanic deposits of shiny, brightly shining, tough nickel layers.

It has been shown that the grain size of gal- ' vanic precipitates can be reduced and the gloss of the nickel precipitate can be increased can, and in a very effective way, if one has certain organic ones which are soluble in the bath Compounds used, especially certain aliphatic esters of unsaturated aliphatic Polycarboxylic acids, the unsaturation of which is based solely on double bonds.

The methyl and ethyl esters of unsaturated aliphatic polycarboxylic acids are particularly satisfactory, which have between 4 and 8 carbon atoms contain; While excellent results have also been obtained using certain Alkoxy-alkyl esters of the unsaturated ones mentioned aliphatic polycarboxylic acids. The esters on whose use the present invention aims belong to the group in which all carboxyl groups are unsaturated aliphatic polycarboxylic acids are esterified.

The following Table I gives a number by way of example Esters, the use of which falls within the scope of the present invention. It's understandable, that the solubility of such esters varies. To get good results you should the esters in the aqueous acidic nickel electroplating bath to an extent of at least about 0.15 g per liter will be soluble. In general it is

it is not necessary to use the more soluble esters in quantities greater than about 3 g per liter. In any case, the esters recommended for use with the invention must be included in be sufficiently soluble in the aqueous acidic nickel electroplating bath to make these esters to enable the reduction of the grain size of the nickel electroplating and the increase to bring about shine.

0.2 to 2.0

Table I.

Esters of unsaturated concentration

Dicarboxylic acids grams / liter

i. Dimethyl fumarate

2. Dimethyl chlorofumarate

3. Dimethyl bromofumarate

4. Di- (2-methoxyethyl) -

Fumarate

5. dimethyl maleate

6. Diethyl maleate

7. Dimethyl Ohlomaleate

8. Di (2-methoxy-ethyl) maleiate

(Di-aMethyl-Cellosolve "- Maleate)

9. Di (2-ethoxy-ethyl) maleate

(Di- »Cdlo-solive« ~ Mlafeät) ..

10. Dimethyl itaconate.,

11. Diethyl itaconate

12. Di- (2-methoxy-ethyl) -

Itaconate

13. Di -_ (2 - [/? - Metlhoxy-Ethoxy] ~

Ethyl) itaconate

14. Dimethyl methylene malonate. 15. Dimethyl glutaconate

16. Dimethyl mesaoonate

17. Dimethyl citraconate

18. Dimethyl crotilydene malonate

19. Methyl ethyl maleate,

20. Methyl / 2-methoxy-ethyl

Fumarate

21. Di (2-ethoxyethyl) fumarate

22. Di (2-ethoxy-ethyl) itaconate.

Esters of unsaturated concentration

Tricarboxylic acids grams / liter

i. Trimethyl ethylene

tricarboxylate

2. Trimethyl-a-propylene, α, α, γ-

Tricarboxylate

3. Trimethyl isoaconitate (trimethyl-a-propylene-a, γ, γ-

Tricarboxylate)

4. Trimethyl aconitate (trimethyl-a, ß, y-tricarboxylate)

5. Trimetfayl-Aylenetri-

carboxylate

6. Trimethyl oxalcitraconate ... 0 f. Tr i- (2-Met5hoxy-ÄHiyl) -

Aconitate

8. Tri- (2-methoxy-ethyl)

Ethylene tricarboxylate

0.2 to 2.0 esters of unsaturated
Tetracarboxylic acids

1. Tetramethyl-ethylene-tetra-

carboxylate

2. Tetramethyl-γ-carboxylate

Aconitate

3. Tetramethyl-a-carboxylate

Aconitate

4. Tetramethyl-a, y-dicarboxylate

Glutaconate

Concentration gram / liter

o, 2 to 2.0

The esters of 2-methoxy-ethanol, 2-ethoxy-ethanol, such as. B. Di- (2-methoxy-ethyl) fumarate, di- (2-methoxy-ethyl) -maleate, tri- (2-methoxy-ethyl) -aconitate, di- (2-Ä.tlioxy-ethyl) - Maleate, di (a-ethoxy-ethyl) fumarate; The methyl esters, such as DimethyHMJaleät, Dimethyl-Fumarate, Trimethyl-Aconitat and ^1- Dimethyl-Itaconate, which are used either alone or in a mixture with one another or in conjunction with organic sulfur-containing gloss agents, as will be described in more detail below, are also equally advantageous.

Ee has also been shown that when using a small amount of a shimmer of the stilfon, sulfonamide or sulfonimide type in Combination with the aforementioned esters, exceptionally bright, high-gloss, tough nickel plating can be obtained which have excellent adhesive properties to the base metal exhibit. Since the use of glossers of the aforementioned organic sulfone type and also of the sulfonamides and sulfonimide types are considered to be previously known and, for example, in the USA patents 2J191813 and 2466677 the invention cannot generally relate to the use of such gloss generators. in the In the context of this phase of the present invention, there is a cooperation in the cathode coating instead, the nature of which is not known; in this interaction are the esters of the aliphatic unsaturated polycarboxylic acid and the organic sulfur-containing gloss agent involved. the Interaction has the 'unusual' and yielded extremely significant results produced in accordance with this aim of the invention will. In this connection it should be noted that the use of the esters of the aliphatic unsaturated polycarboxylic acids alone or the use of the organic sulfur-containing Gloss-giver alone does not suggest which one, the remarkably improved results occur in the simultaneous presence of both types of connection, especially if the same are used in their optimal concentrations. Typical examples of organic Sulfur-containing glossers, which can be used in the context of the invention, in conjunction with the esters of aliphatic unsaturated polycarboxylic acids are in U.S. patents 2191813 and 2466677 as well as in the following Table II listed.

Table II

Optimal sulfur-containing luster concentration

Grams / liter j

1. Benzene sulfonamide 0.1 to 3

2. Toluene sulphonamide (o- and p-) .. 0.1-2

3. o-Benzoyl sulfimide 0.1-2

4. N-Benzoyl-Benzene-Sulphonimidi ... 0.1 - 1 5. p-Toluene sulfochloramide 0.1-1

6. p-Bromo-benzene-sulfonamide 0.1-1

7.6-chloro-o-benzoyl sulfimide 0.1-1

8. m-Aldehydo-benzene-sulfonamide. 0.1 - 1

9. Sulfomethyl benzene sulfonamide. 0.1 - 6 10. Benzene-sulfonamide-m-carboxyl-

Amide 0.1-3

11.7-aldehyde-o-benzoyl sulfimide. 0.1-3

12. N-Acethyl-Benzene-Sulphonimide ¹ ... 0.1-2

13. Methoxy-benzene-sulfonamide 0.1-1

14. hydroxymethyl benzene

Sulfonamide 0.1-2

15. Vinyl sulfonamide 4.0-12

16. Allyl sulfonamide 4.0-12

17. Benzene sulfo acids

(mono-, di- and ¹ tri-) 1.0 - 15

18. p-Bromo-benzene-sulfonic acid 3.0-6

19. Benzaldehyde sulfonic acids

(0-, m-, p-) 2.0-6

20. Diphenyl sulfonic acid 1.0-8

21. Naphthalene sulfonic acids

(mono-, di- and tri-) i, o - 8

22. Benzene sulfohydroxaniic acid .. 1.0-5

23. p-chloro-benzene-sulfonic acid 1.0-15

24. Diphenyl sulfonic acid 1.0-5

25. m-Diphenyl-benzene-sulfonic acid .. 1,0-4

It is understandable that the said sulfur-containing Luster in their acid form or in the form of salts, such as. B. nickel, sodium, Potassium or other salts, can be used. For the practice of the invention those compounds give particularly satisfactory results which are listed in Table II correspond to numbers 1, 2, 3, 18, 19, 21 and 28, the latter in particular in the form of their nickel salts.

When sulphonic acids are mentioned in the following, these are also included in the same way Understand salts.

The compounds of Table II produce brilliant and mirror-like precipitates highly polished metals, e.g. B. Brass. However, the same results will, at least normally, not produced on Sta'M, which is polished with 180er emery, and also not on dull but unfired copper plates from 0.0076 to 0.0127 mm; in the latter cases the compounds provide precipitates somewhat dull and gray in appearance. The connections according to table I normally result in a lower type which is different from that according to Table II achievable precipitation type. Those prepared with the aid of compounds according to Table I ' Deposits are generally cloudy and cloudy when applied to polished or dull metal cloudy. The rate at which the gloss of the base metal is improved going on is much greater when using compounds according to Table I than in the case of the Use of compounds according to Table II. If, however, the two different types of connection according to Tables I and II are common in the baths are used, as stated above, brightly shining, receive mirror-like precipitation, even on dull surfaces.

Usually, compounds according to Table I are consumed more quickly during the electroplating process than the compounds according to Table II. The compounds according to Table I have a larger one Reduction rate with respect to the nickel ion on the nickel cathode while the connections generally have a slower speed according to Table II; that means, that the nickel ion is reduced with preference in the latter case.

The aqueous galvanic nickel baths can be of various types; but in all cases they have acidic character. The baths of the so-called Watt type or modifications are preferred the same. The nickel salts can be nickel chloride, nickel sulfate, nickel fluoroborate, Nickel sulfate or other nickel salts or any mixtures thereof, preferably in conjunction with buffer substances, such as B. boric acid. The use of boric acid is recommended for the bathroom because they are generally the best means of controlling the acidity of the Kathadenfilm represents. However, other acidic control means may be used, such as Formic acid, fluoroboric acid and the like; these acids can either be used in place of boric acid or used in conjunction with boric acid. For best results you should the concentrations of boric acid or its equivalent are above 30 g per liter, in particular in baths that are operated at slightly elevated temperatures. The bathrooms can also be different contain additional funds, such as B. Means that the erosion and scarring counteract.

Table III lists preferred Given bath compositions.

As stated above, the Concentration of the compounds listed in Table I in the bath between about 0.2 and about 3 g per liter fluctuate. For best results the range is between about 0.6 and 2 ^ g per Liters usually approximately correct. In certain and perhaps most cases, these concentrations will be for the particular esters used, close to the saturation limit. Continuous filtration and the use of surface acting agents to prevent the Promote scarring, at least to some extent, the solubilization of the verb

Table III

Bathroom no. NiSO ₄ -OH ₂ O
Grams / liter NiCl ₂ -OH ₂ O
Grams / liter H ₃ BO ₃
Grams / liter temperature
⁰ C optimum
for Ph Allowance I. 300 40 40 40 to 50 2.8 to 4.8 Dimethyl fumarate
2 g / l 2 300 40 to 75 40 40 to 65 2.8 to 4.8 Di (2-metrioxy-ethyl) -
Maleate 2 g / l plus
Benzene sulfonamide
2 to 3 g / l and / cder
o-BenzoyL sulfimide
• 0.1 to 2 g / l 3 300 40 40 40 to 65 ^ 2.8 to 4.8 Trimethyl aconitate
2 g / l 4th 300 40 40 40 to 65 2.8 to 4.8 Trimethyl ethylene
Tricarboxylate 2 g / l
plus o-benzoyl-sul-
fimid 0.1 to 2 g / l 5 300 ■ '· 40 · -40 - 40 to 65 2.8 to 4.8 Tetramethyl ethylene
Tetracarboxylate
2 g / l 6th 300 40 to 75 40 40 to 65 2.8 to 4.8 Tetramethyl ethylene
Tetracarboxylate
2 g / l plus benzene
Sulfonamide 2 gl '■ 7th 0 to 100 0 to 40
Ni (BF ₄ ) ₂ -
100 to 300 0 to 40 40 to 65 2.8 to. 5.0 Trimethyl aconitate
2 g / 1

fertilize according to Table I; these · 'apply measures hence for at least most of them. Cases recommended. Where the esters after. Table I- -which for · the use If selected, have an appreciable vapor pressure at the temperature at which the bath is operated, a suitable one should be Ventilation may be provided.

The baths can at temperatures! operated between room temperature and .45 are almost boiling temperature; but in general We recommend a temperature between about 40 and 65 ° C. Where the baths at slightly elevated temperatures are operated, the selected esters of unsaturated, aliphatic polycarboxyl

acids such that they remain stable at the bath temperatures. In general, the baths can be operated at pH values between about 2 and 5%; however, pH values of 3.0 to 4.8 are usually preferred. The cathode current density can vary between wide limits A range of about 0.005 up to 108 amps per square centimeter or a multiple thereof is available, the particular optimum depending on the agitation, temperature, concentration and type of nickel salts used in the bath , 0216 to about 0.086 amps per square centimeter f>■> - ■ - '· "■ - ■■ - , ■:": -'-'. '. ::; r.; V-

Most of the compounds of Table I are at _pH values of about 3.8 to 4.5, and at bath temperatures of about 45 to 6o ° optimally effective. In general it can be said that the lower the bath temperature the higher the _pH value is, in which the bath is to be operated to achieve optimum results'.

It should be noted that even if certain esters according to Table I, -z. B. dimethyl fumarate, are very useful to reduce the grain size and to achieve a tough, glossy, but cloudy precipitate when they are used alone, such esters are not necessarily best to be considered in conjunction with sulfur-containing glossers To achieve the production of luminous, mirror-like deposits on dull metal surfaces. Thus, for example ^1X 5 a better overall effect achieved by using di (2-methoxy-Ä'thyl) maleate in association with o-Benzöyl-Sulflmid as with dimethyl fumarate in conjunction with o-benzoyl sulfimide. In addition, the di (2-methoxyethyl) maleate has the practical advantage over dimethyl fumarate that it is less volatile and can be handled more easily with regard to odor, skin effects and the like.

It was also found that the existence of free 2-methoxy-ethanol or

2-phenoxy-ethanol or the like. In the bath, namely in a concentration of about ι to 15 g per liter or even more, the glossy effect of the S parts supports, at which medium or lower current density exists, especially when the connections according to Table II with the compounds according to Table I come to use. The free 2-methoxy-ethanol or similar compounds can be contained in the reaction mixture, which results from the Voriereitungsverfahren the esters of such ethanol derivatives, z. B. Di- (2-methoxy-ethyl) maleate, result. But they can also be added to the baths as such.

It is understandable that from time to time it is necessary to replenish the bath in order to compensate for losses, caused by the cathodic processes, the wetting of the workpieces and other causes are conditional, so that the concentrations of the added esters etc. in the correct proportions be maintained.

If unsaturated esters (Table I) without organic sulfur compounds (Table II) in the Nickel baths are used, especially baths with a high content of nickel sulfate and low content of nickel chloride, such as. B. Baths 1 to 6 of Table III, it is often advantageous Means for binding or removing polyvalent cations of copper, nickel, calcium, To use iron and the like. Such means are both

like trimethyl-Arniina, a, a ", y-tricarboxylic acid, ethylene-diamine-tetra-acetic acid or their salts in concentrations up to about 3 g per liter contribute plating generated, particularly when the p _H values are between about 3.5 and 5) °.

Claims (26)

PATENT CLAIMS: 1. Bath for the galvanic deposition of nickel, characterized by its composition from an aqueous, acidic solution of at least one nickel salt, a solution of a smaller proportion of at least a fully esterified aliphatic ester of an unsaturated aliphatic which is soluble in the bath Polycarboxylic acid, the unsaturation of which is due solely to double bonds. 2. Bath according to claim 1, characterized in that that the nickel salt comes from the group consisting of nickel chloride and nickel sulfate and that no more than 0.5% ester of a polycarboxylic acid is for use which contains between 4 and 8 carbon atoms. 3. Bath according to claim 2, characterized in that 'the ester of di- (2-methoxy-ethyl) maleate 'consists. 4. Bath according to claim 2, characterized in that the ester of di- (2-methoxy-ethyl) fumarate consists. 5. Bath according to claim 2, characterized in that the ester of di- (2-methoxy-ethyl) itaconate consists. 6. Bath according to claim 2, 'characterized in that the ester of di- (2i-ethoxy-ethyl) maleate consists. 7. Bath according to claim 2, characterized in that the ester of di- (2-ethoxy-ethyl) fumarate consists. 8. Bath according to claim 2, characterized in that the ester of di- (2-ethoxy-ethyl) itaconate consists. 9. Bath according to claim 2, characterized in that at least one ester from the Group contained in the bath, which di-methyl esters of maleic acid, fumaric acid and Itaconic acid includes. 10. Bath according to claim 2, characterized in that the ester of trimethyl aconitate consists. 11. Bath according to claim 1, characterized by adding at least one gloss agent from the group which organic Sulfonamides, sulfonimides and sulfonic acids. 12. Bath according to one of claims 2 to 10, characterized by the addition of no more than about 0.5% of at least one brightener the group which includes organic sulfonamides, sulfonimides and sulfonic acids. 13. Bath according to claim 12, characterized in that that the gloss generator consists of benzene sulfonamide. 14. Bath according to claim 12, characterized in that that the gloss generator consists of p-ToluoI sulfonamide. 15. Bath according to claim 12, characterized in that that the shimmer from o-benzoyl sulfimide consists. 16. Bath according to claim 12, characterized in that that the ester consists of di- (2-methoxy-ethyl) maleate and that the bath also has a small content of 2-methoxy-ethanol. 17. Bath according to claim 12, characterized in that ^! the ester consists of di- (2-methoxy-ethyl) -itaconate and that the bath also contains a small amount of 2-methoxy-ethanol. 18. Process for galvanic nickel plating with the production of a fine-grain deposit, characterized by the use of a bath according to claim 1 for the implementation of electrolysis. 19. Process for galvanic nickel plating with the production of a fine-grain deposit, characterized by the use of a bath according to claim 2 for the implementation of electrolysis. 20. Process for galvanic nickel plating with the production of a bright, shiny and viscous deposit, characterized by the use of a bath according to claim 11 for carrying out the electrolysis, the nickel salt belonging to the group which nickel chloride and nickel sulfate. 21. Process for galvanic nickel plating producing a bright, shiny and viscous precipitate, characterized by the Use of a bath according to claim 12 for carrying out the electrolysis, wherein the Nickel salt, belonging to the group which includes nickel chloride and nickel sulate. 22. Preparation intended for use as an additive to aqueous, acidic nickel salt solutions for electroplating Nickel plating, characterized in that the preparation has at least one gloss generator, which of the consisting of organic sulfonamides, sulfonimides and sulfonic acids Belongs to the group and a fully esterified aliphatic ester which is soluble in the bathroom Contains unsaturated aliphatic polycarboxylic acid, the unsaturation of which only contains Double bonds based. 23. A preparation according to claim 22, characterized by the ester of a polycarboxylic acid, which contains 4 to 8 carbon atoms. 24. Preparation according to claim 22 and 23, characterized by at least one ester the group that contains the methyl esters of maleic acid, Includes fumaric acid and itaconic acid. 25. Preparation according to claim 22 and 23, characterized by a di (2-methoxy-ethyl) ester of a dicarboxylic acid, 26. A preparation according to claim 22 and 23, characterized in that the ester of trimethyl aconitate consists. © SÄ43 12. SJ