DE1224942B - Process for the electrodeposition of metals - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

C22d

German class: 40 c-1/00

Number: 1 224 942

File number: J 26979 VI a / 40 c

Filing date: November 25, 1964

Opening day: September 15, 1966

In the case of galvanic deposition processes, such as B. electrolytic refining or electroplating, where the metal is deposited on a cathode, it is essential that the deposited material can subsequently be easily removed from the cathode. So far, this requirement has not always been satisfactory has been achieved. Various solutions are already available to remedy this deficiency suggested such. B. the use of mold release agents, but these solutions are not always been quite successful.

The object of the invention is to provide a method for electrolytic To provide deposition in which the deposited material is easily removed from the cathode can on which it is deposited. The invention also relates to a cathode, which in such Procedure can be used.

According to the present invention, these objects are achieved in a method for electrolytic Deposition is achieved in that the cathode on which the deposition takes place consists of an electrical one conductive synthetic rubber.

As suitable for such a cathode electrically conductive synthetic rubbers can be, for. B. Conductive butyl, chloroprene, butadiene-styrene copolymers, butadiene-acrylonitrile copolymers and use polysulfide rubbers and conductive silicone rubbers.

The hardness and flexibility of the cathode can be determined by changing the proportions of its components vary to achieve the final properties desired. Should z. B. a proportionate Crumbly granular material is deposited, so it becomes about a soft, very pliable material Easiest to remove cathode. On the other hand it can be used for a thick, cohesive one deposited metal plate an almost rigid cathode have the best separation properties. One can optionally support or reinforce the cathode with z. B. metal or fabric, such as. B. glass linen, to increase strength or electrical conductivity. For mechanically weak materials, like silicone rubbers, the electrode is preferably supported or reinforced.

The synthetic rubbers used can be brought into the desired cathode shape by manufacturing processes known per se and by vulcanization or, if appropriate, hardening. The conductivity can also be achieved in a manner known per se, for example by means of conductive fillers such as carbon black and metal powder. The conductivity of the material electrodeposition process
of metals

Applicant:

Imperial Chemical Industries Limited, London

Representative:

Dr.-Ing. H. Fincke, Dipl.-Ing. H. Bohr
and Dipl.-Ing. S. Staeger, patent attorneys,
Munich 5, Müllerstr. 31

Named as inventor:

John Graham Tapley, West Kilbride

(Great Britain)

Claimed priority:

Great Britain November 25, 1963 (46 441)

the cathode is normally adapted to the operating conditions that occur in each case. However, their specific resistance is usually not higher than 100 Ohm / cm.
Although a variety of electrically conductive synthetic rubbers can be used, a conductive silicone rubber is preferably used in many cases. This rubber can be produced from a mass curable at elevated temperature or from a mass curable at room temperature and by z. B. molding, extrusion, injection onto a textile or wire mesh or other known methods. Such conductive elastomeric compositions are known and can be easily obtained.

Although the cathodes according to the invention already have sufficient separation properties, can this, if necessary, can be further increased by a release agent, such as. B. a silicone liquid to the Cathode is applied prior to deposition.

The substances that can be electrodeposited with the method according to the invention are including metals such as copper, silver, gold, zinc and cobalt and other similar materials. The invention is explained below on the basis of exemplary embodiments, all quantitative data relate to weight unless otherwise stated.

609 660/346

example 1

The following ingredients were mixed together:

Methylvinylpolysiloxane (0.1 mole percent vinyl groups: average molecular weight 750,000) 100

Acetylene Black Average
size 42 ηαμ: area 65 m Vg) · · · 65

RauchMesel [coated with 20% octamethylcyclotetrasiloxane] (average particle size 10 to 40 μm: surface area
175 τη ² / ε) 10

Methylhydrogenpoiysiioxan '(average molecular weight 2000: H: Si as 0.96: 1) 5 ¹ S

Platinum in the form of cyclohexene-chloroplatinum

Complex 0 004

^The resulting mass was molded as a plate and ^{subjected to a pressure of 35 kg / cm 2} at 170 ° C. for 15 minutes, a 6.35 mm thick hardened plate being obtained. This plate was then heated in a forced air oven at 250 ° C for 24 hours.

The physical properties of the hardened plate were measured and showed the following values:

Elongation at break 120%

Tear strength 2.722 kg

Tensile strength 36.75 kg / cm ²

Hardness 84 ° BS

The specific electrical resistance according to BS standard 2044 (1953) was 4 ohm / cm.

A part of the plate produced in this way was then used as a cathode in a copper plating bath. The bath contains 40 g / l copper in the form of copper sulphate and 200 g / l sulfuric acid. The anode was formed by a copper sheet in the bath parallel to the cathode. A direct current flowed through the bath for 5 hours, the current density at the cathode being 215.3 A / m ² and the bath being continuously stirred to avoid polarization. The resulting copper deposit could easily be peeled off the silicone rubber cathode, the rubber showing no visible damage and only a trace of the black mass adhering to the peeled copper.

The described operation of deposition and stripping was repeated five times, whereupon the rubber has been examined for damage. There was no damage seen, and the separation of the copper from the cathode was not affected at all.

The thickness of the deposited copper layer often increased with increasing distance from the electrical layer Junction on the silicone rubber sheet because of the noticeable resistance of the rubber.

Example 2

The formation of a plate from conductive silicone rubber was carried out according to Example 1, with the difference that the mass to form the plate was pressed in close contact with a clean, degreased zinc plate. A cured silicone rubber plate was thus obtained, which was firmly bonded to a zinc plate over its entire surface. The electrical efficiency of the connection was tested by measuring the resistance between the zinc plate and the exposed surface of the conductive rubber locally with a probe having a diameter of 1 mm. Resistance differences of only a few percent were found.
,? ^ie ™ ^k the zinc plate reinforced rubber electrode was copper plating m EMEM ^Wle Example 1 was used as a cathode, wherein the ZmK-P ^1! ** ^{against. d} j? The liquid was protected by a thick layer of insulating confection. Jf? Deposited copper was easily peeled off from the silicon rubber plate. After a five-time implementation of a deposition and separation ^was adjusted ^ ^eme superficial damage phenomena solidified on rubber or an error in the connection between the Kautechuk and the zinc plate. The feasibility of separating was not made difficult at all.

In this case the deposition was much more uniform than in example 1. The metal-reinforced The cathode was also much stronger mechanically and could be bent into various stable shapes will.

Example 3
The following ingredients were mixed:

»: Ω - dihydroxydimethylpolysiloxane (average molecular weight 65,000) 100

Acetylene black (average particle size 42 ηιμ .: area 65 m ² / g) 50

^Ki f ^el ^ ^r (average particle size 2 to

ÄthvTsnicat 3

Ainyisuicat

Subsequently, the mixture was dispersed in toluene, to thereby ig to form a dispersion having a 30% ^e n solids.

1.5% of dibutyltin dilaurate were then added to the dispersion, which was then poured onto a thin Aluminum sheet was applied. The resulting paint was air dried for 24 hours cured at 20 ° C.

The aluminum sheet provided with the conductive silicone rubber layer was then, as in Example 1, copper-plated. After 3 days, the deposited copper could very easily be removed from the rubber-coated one Peel off sheet metal. There were no signs of silicon or contamination with the copper Carbon detectable.

Example4

A dispersion with 20% of the mass according to Example 1 in toluene was prepared as the dispersant.

A piece of woven glass linen (desized) with a thickness of about 0.125 mm was immersed ^{in the disper s} i ° ^n. After removing the Glasleinens was allowed thereon excess amount of liquid flow, after which the glass linen dried 1 minute heated to 70 ⁰ C air. The dry but not cured rubber film obtained in this way was then cured by heating to 160 ° C. for 15 minutes. The resulting coating was about 0.05 mm thick and had a surface resistivity of 260 ohms.

The rubber film reinforced with the glass cloth was used as a cathode in a copper plating bath, such as in Example 1, used. Since the cathode is a

had a relatively high resistance, a current density of only 3.9 A / m ^{2 was} used. After 24 hours an initial copper layer was deposited, after which the current density was increased to 15.1 A / m ² and the copper plating was continued for 72 hours. The electrodeposited copper layer could very easily be peeled off the silicone rubber cathode reinforced with glass elements, the rubber not suffering any visible damage and only a trace of the black rubber mass adhering to the copper. The force required to peel the silicone rubber cathode reinforced with glass cloth from the copper layer was measured at a separation speed of 50.8 cm per minute and was found to be about 300 g per 2.5 cm width.

Claims (3)

Claims; 1. Process for the electrolytic deposition of metals, especially copper, silver, Gold, zinc or cobalt, from aqueous solutions, characterized in that as Material for the deposition cathode is an electrically conductive synthetic rubber, preferably Silicone rubber, is used. 2. The method according to claim 1, characterized in that the synthetic rubber by Metal or fabric is worn or reinforced. 3. The method according to claim 2, characterized in that the metal or fabric is a metal plate or a glass linen fabric is used.