FR2496131A1 - SUBSTRATES HAVING A WHITE METALLIC PALLADIUM DEPOSIT - Google Patents

Abstract

ELECTROLYTICALLY COATED METAL PALLADIUM DEPOSITS ON SUBSTRATES SHOW A WHITE COLOR WITH AVERAGE WHITE LIGHT REFLECTING POWER VALUES, AS DETERMINED BY SPECTROPHOTOMETRIC METHODS, RANGING FROM ABOUT LOWOYPYPEN OF BLANCIER 78 OF PANCIER DE LANCIER DE LANCIER 78 OF PANCIER DE LANCIER DE LANCIER 78 RHODIUM METALLIC FOR THE SAME WAVELENGTHS, AND IN ADDITION, THESE METAL PALLADIUM DEPOSITS ARE VERY SMOOTH AND SENSITIVELY FREE OF DENDRITIC DEPOSITS.

Description

1. The present invention relates to thin electrolytic deposits

metallic white palladium on

  conventional substrates, these deposits having the appearance of rho-

white dium.

  As is known in the art, conventional electrolyte deposits of palladium are gray in color. Electroplated rhodium deposits, on the other hand, are white and are very useful in the decorative arts industries. Owing to the relatively high cost price of rhodium in comparison with palladium, it

  it would be desirable to be able to obtain a white finish from

  bath firing with palladium, as a substitute

  cementing of rhodium finishes now in use. Temptations

  prerequisites for producing a palladium metal deposit

  white lists were not successful because the repository was not white enough for the intended purposes, for

  example as a substitute for standard deposits

  white rhodium sics. It will be useful for commercial purposes to be able to easily obtain white deposits

and thin metallic palladium.

  U.S. Patent No. 330,149, which was granted to Pilet et al. In 1885, really mentions the

  production of a "white palladium deposit". The bath of re-

  electrolytic clothing from Pilet and collaborators

  2. is born of palladium chloride, ammonium phosphate,

  sodium phosphate or ammonia, and, optionally

  tative, benzoic acid. The operating pH of the bath is not described, although it is indicated that the ammonia is "boiled off" and that "the liquid which was

  alkaline becomes slightly acidic. "As noted, the use of

  benzoic acid is described as being optional

  tive, but patentees say it whitens the deposit and makes the deposit more likely to form de-very thin

  coatings on iron and steel.

  Electrolytic coating baths which are designed to improve the gloss of deposits of palladium or palladium alloys on metal substrates are also known in the art. We will refer,

  for example, to U.S. Patent No. 4,098,656 which was granted

  strung at Deuber in 1978. In this patent, the improved brilliance

  This is achieved by using in the bath both a Class I organic shine agent and a Class II organic shine agent, as well as a

  pH range set between 4.5 and 12.

  In the attached drawing, the single figure is a

  graph which illustrates the whiteness of electrolytic deposits

  of palladium of the present invention, by comparison

its with the prior art.

  According to the present invention, single deposits

  electrolytically coated with white metal palladium-

  lique are formed on a suitable substrate. These deposits

  are characterized by average values of power

  white light reflector that goes from about

  ron 78 to 95%, preferably about 82 to 95, of the

  see medium rhodium white light reflector for

  the same wavelengths. These deposits are, moreover, charac-

  terrified by the fact that they are very smooth and noticeably

free of dendritic deposits.

  Using known spectrophotometric methods and devices, such as the Perkin-Elmer 559 spectrophotometer, deposits of palladium and rhodium 3 were explored on the visible light spectrum ranging

  from 400 to 700 nanometers. Based on the reflectivity

  average white light content of metallic rhodium, the following minimum values in percentage have been obtained for the metallic white palladium deposits of the present invention:

Based on the percent-

  metallic rhodium reflecting power level Nanometers Wide range,% Preferred range,% 400 at least 78 at least 83,500 at least 88 at least 92,600 at least 90 at least 94,700 at least 91 at least 94

  These unique deposits of white palladium are formed

  measured on any suitable substrate, such as steel, nickel, copper, zinc, precious or noble metals and the like. Deposits are about 0.01 to 1.0 micron thick, about 0.03 thick

0.4 micron being preferred.

  In determining the whiteness characteristics

  cost of these deposits, as presented above, these characteristics

  are indicated quantitatively depending on the

  white light reflecting power measured by

  spectrophotometric dice. These values were measured using a Perkin-Elmer 559 spectrophotometer, although

  that other similar instruments may be used.

  The deposits to be measured were coated on panels-

  2.54 cm x 2.54 cm steel which had been pre-coated with 0.0127 mm copper and then with 0.0127 mm nickel, to eliminate surface imperfections. These panels are

  hereinafter referred to as panels coated with ni-

ckel.

  The white light reflecting power of the

  posts on these panels have been explored in the transmitted-

  sion made between 400 and 700 nanometers compared to a reference plate made of magnesium oxide. The scanning of the 4. sample deposits of the present invention was then compared to a similar scanning of a rhodium deposit to obtain the percentage reflectance values.

data above.

  As will be described below, these unique deposits

  metallic white palladium can be obtained using

  reading some electrolytic coating baths pres-

  crits, containing metallic palladium.

  Electro-coating baths and processes

  lytique which can be used to produce single deposits of white palladium are described in detail in French patent application No. 81/22682 filed December 3, 1981 under the title: "Composition and process

  for electroplating white palladium on di-

  verses surfaces ", in the name of the so-called company: HOOKER CHE-

  MICALS & PLASTICS CORP. (Corresponding to Case No. S-10.916), in French patent application No. 81/22680 filed on

  December 3, 1981, under the title: "Baths and electrical process

  trolytic for the deposition of white palladium ", on behalf of the

  HOOKER CHEMICALS & PLASTICS CORP. (correspond-

  in Case No. S-10.924) and in French patent application No. 81/22681 filed on December 3, 1981, under the title: "Electrolytic coating baths to obtain white deposits of metallic palladium, containing a source of palladium, a ammonium salt, an organic shine agent and ammonia ", on behalf of the company called HOOKER CHEMICALS & PLASTICS CORP. (corresponding to the Case

no S-10.930).

  In general, these electrolytic coating baths are stable aqueous solutions containing a source of

  palladium soluble in the bath, an ammonium salt conduc-

  soluble in the bath and one or more additional components, comprising ammonia to adjust the pH of the bath to the desired level in a pH range of 5 to 10; buffers, to maintain the desired pH of the bath; chloride ions; an organic gloss product and a mineral gloss product containing nickel. 5. The bath-soluble source of palladium can be any amino complex of palladium, such as

  nitrate, nitrite, chloride, sulphate complexes

  fate and sulfite. Typically among these complexes which can be used are palladium diaminodinitrite and palladosamine chloride. The quantity of

  palladium in the bath will be at least sufficient to

  put palladium on the substrate when the bath is electric

  trolyzed, but less than that which will cause a blackening

  deposit. Typically, the concentration of pal-

  ladium will be about 0.1 to 20 grams per liter, con-

  centering of about 1 to 6 grams per liter being preferred

  rees. The ammonium salt for conductivity in the bath can be any mineral salt containing ammonium, soluble in the bath, such as phosphate diammonium ammonium, ammonium sulphate, ammonium chloride and the like. Mixtures of these salts can also be used. The amount of ammonium salt for conductivity in the coating bath will be at least that which will provide sufficient conductivity in the bath

  to electroplate palladium up to

  that at the maximum solubility of salt in the bath. Typically, the ammonia salt for conductivity will be present in

  approximately 25 to 120 grams per liter, quantities

  tees of about 30 to 100 grams per liter being preferred.

  Typical among electric coating baths

  trolytics preferred which can be used, there are the following: Component Concentration Pd (NH3) 2 (N02) 2 1 to 6 g / l (as Pd) Conductive salt 50 to 100 g / l Ammonia 10 to 50 ml / l Buffer 0 to 50 g / l * Palladium diaminodinitrite bath pH 9-9.5 6. Component Palladosamine chloride Conductive salt Potassium chloride Organic brightener Mineral brightener Ammonia bath pH 5-8 Pd component (NH3) 2 (N02 ) 2 Conductive salt Organic gloss (Class I or II) Ammonia Buffer Concentration 1 to 6 g / 1 (as Pd) to 70 g / 1 to 20 g / 1 i to 3 g / 1 0, 2 to 0.5 g / 1 0 to 15 ml / 1 Concentration 1 to 6 g / 1 (as Pd) to 100 g / 1 1 to 3 g / 1 to 50 ml / 1 0 to 50 g / 1 * Diaminodinitrite of palladium pH of bath 9-9.5 In the coating process using these baths, the temperature of the palladium coating bath can be

  maintained between room temperature and 71 C. To avoid

  ter the emission of an excess of ammonia, the temperature of the

  coating will preferably be below about 55 C.

  For many purposes, operations at am-

  biante are preferred. Current densities of about 0.01 to 5.0 A / dm2 are suitable. Typically, current densities of 0.2 to 2.0, and preferably about 1.0

A / dm2 can be used.

  The present invention will be more fully understood.

  se according to the following illustration examples, where the

  temperatures are given in degrees centigrade. In each

  none of these examples, the coating is produced to produce

  re a deposit of white palladium having a thickness of 0.25-

0.35 micron.

EXAMPLE 1

  An electrolytic palladium solution was 7. prepared by dissolving the following ingredients in water: Component Concentration Palladium diaminodinitrite 2 g / i (as Pd) Ammonium diacid phosphate 95 g / i Ammonia 24 ml / i

  The amount of ammonia used in the formula-

  tion above sets the pH to about 9.2. The coating was carried out at room temperature, at a density

  current of 1.0 A / dm2 and for 45 seconds on a panel

nickel coated calfskin.

EXAMPLE 2

  A semi-coating bath was formulated as follows

  blable in Example 1, but with the use of a buffer Component Concentration Diaminodinitrite of palladium 2 g / l (as Pd) Ammonium diacid phosphate 96 g / l Ammonium diborate 25 g / l Ammonia 24 ml / l

  The amount of ammonia used in the formula-

  tion above also sets the pH to about 9.2. The re-

  The garment was produced at room temperature, under a current density of 1.0 A / dm2 and for 45 seconds on a panel coated with nickel. Ammonium diborate was used

  of buffer to maintain the pH at the desired level.

EXAMPLE 3

  The coating bath was similar to that of

  Example 2, with one exception, is that tetrabora-

  te sodium was used as a buffering agent. The formula-

  tion was as follows Component Concentration Palladium diaminodinitrite 4 g / l (as Pd) Ammonium ammonium phosphate 50 g / l Ammonia 24 ml / l Sodium tetraborate 25 g / l 8.

  The aqueous solution contained sufficient am-

  moniac to adjust the pH to 9. The coating operations-

  were carried out under the same conditions as for

examples 1 and 2.

EXAMPLE 4

  A palladium electrolyte solution was prepared by dissolving the following ingredients in water: Component Concentration Palladosamine chloride 2 g / l (as Pd) Ammonium sulfate 60 g / 1 Potassium chloride 15 g / l Sodium benzaldehyde-o-sulfonate 2 g / 1 Ammonium and nickel sulfate 0.5 g / 1 The pH of the coating bath was 5.5 to 7 during coating operations, at a temperature of 45-55 C

  and at a current density of 1.0-2.0 A / dm2 on a panel

nickel coated calfskin.

EXAMPLE 5

  An electrolytic palladium solution has been formulated as follows: Component Concentration Palladosamine chloride 2 g / l (as Pd) Ammonium sulphate 30 g / l Potassium chloride 15 g / l Ammonia 8 ml / l Benzaldehyde-o- sodium sulfonate 2 g / 1 Nickel sulfate 0.2 g / l

  The pH of the coating bath ranged from 5.5 to 7 from

  rant operations, at a temperature of 50 C and under a

  current density of 0.4-1.5 A / dm2 on a panel.

EXAMPLE 6

  A palladium electrolytic solution was pre-

  9. prepared by dissolving the following ingredients in water: Component Concentration Palladium diaminodinitrite 2 g / l (as Pd) Ammonium diacid phosphate 96 g / i Ammonium diborate 25 g / l Ammonia 24 ml / i Sodium benzaidehyde-o-sulfonate 2 g / l

  lO The amount of ammonia used in the formula-

  tion above raises the pH to about 9. The coating was carried out at a temperature of 22 C, at a density

  current of 1.0 A / dm2 and for 30 seconds on a panel

  nickel coated calfskin. Ammonium diborate served as

  buffer to maintain the pH at the desired level and to reinforce

  cer the desired whiteness of the deposit resulting from metallic palladium.

EXAMPLE 7

  A coating bath similar to that of the example

  ple 6 but using a different gloss, has been formed

  formulated as follows: Component Concentration Palladium diaminodinitrite 2 g / i (as Pd) Ammonium diacid phosphate 96 g / l Ammonia 24 ml / l Ammonium diborate 25 g / l 2-butyne-1,4-diol 2 g / l The adjusted pH was 9 and the coating process was started under the same conditions as

in the previous example.

EXAMPLE 8

  A coating bath similar to this was prepared

  him from example 6, with one exception prbs, is that a shine-

  Class I nickel lantern was used. The formula-

  tion was as follows: 10. Component Concentration Diaminodinitrite of palladium 1 g / l (in the form of Pd) Ammonium diacid phosphate 50 g / 1 Ammonium diborate 25 g / 1 Ammonia 24 mlil Saccharin 2 g / l

  The aqueous solution contained sufficient am-

  moniac to raise the pH to 9. The coating operations were carried out under the same conditions as

for examples 6 and 7.

  In the following table, the white light reflecting power of the palladium deposits on the nickel-coated panels of Examples 1 to 8 was compared with that of a rhodium deposit on a nickel-coated panel, as well as with that of the deposits made according to example 3 of the patent

  American No. 4,098,656 from Deuber and according to 11 American patent

  cain n "330.149.de.Pilet (page 1, lines 77-102 and page 2, lines 1-8). The deposits of Pilet and Deuber, like those of examples 1-8, were 0.25 thick - 0.35 micron As described above, the spectrophotometer says

  Perkin-Elmer 559 was used. More specifically, the ba-

  layering of the various nickel-coated panels, which are re-

  clad in metallic deposits, is carried out in the transmission mode between 400 and 700 nanometers compared to a

  magnesium oxide reference plate.

11.

BOARD

  Previous results indicate that the baths

  electroplating coating of the present invention

  reduce a significantly improved metallic palladium deposit

  as for the reflectivity of white light, by

  parison with the deposits of Deuber and Pilet. The difference

  visual whiteness is so important that for

  commercial applications, this may be the difference between

acceptance and rejection.

  When representative examples of the results

  precedents belonging to the present invention are por-

  ted graphically, that is to say that the percentage of

  see reflector is worn depending on the length of

  of, with respect to a deposit of metallic rhodium as well as with respect to the deposits of metallic palladium of Deuber and Pilet, the resulting graph indicated on the attached drawing reveals the importance between the deposits of metallic palladium of the present invention and the deposits of the

prior art.

  Scanning Electron Microscope (SEM) Micrographs were performed for the deposits produced in Examples 2, 4 and 6 and for those produced by the operating procedures of the patents of Pilet and collaborators and A of reflective power Deposit 400 nm 500 nm 600 nm 700 nm Rhodium 80.5 85.0 88.5 90.5 Deuber 60.0 71.5 78.0 80.5 Pilet 51.5 60.0 66.5 72.0 Example 1 -63.5 75, 0 80.0 82.5 Example 2 64.5 75.5 81.0 83.5 Example 3 63.0 74.5 80.0 83.0 Example 4 66.0 76.5 81.5 84.0 Example 5 67.0 77.0 82.0 84.5 Example 6 67.0 78.0 83.0 85.0 Example 7 66.0 75.5 80.5 83.0 Example 8 67.0 77.0 81 , 5 83.5 12. de Deuber. These Micrographs show that the deposit of Pilet et al. Has significant dendritic deposits and a

  rough appearance on the surface. The Deuber depot, while pre-

  feeling somewhat reduced dendritic growth compared to Pilet et al., still has a rough appearance on the considerable surface. In contrast, the deposits for Examples 2, 4 and 6 were smooth to extremely

  smooth, with no dendritic deposits in the samples

  from examples 2 and 6. The sample from example 4 really gave very small amounts of

  dendrites but these-dendrites were in much smaller quantity-

  dre than those in the Deuber deposit, and the overall smoothness on the surface was clearly superior. This further illustrates the unique properties of the white palladium deposits of the present invention and indicates the correlation between

  the smooth appearance of the deposit and its light-reflecting power

re white.

  The appreciation of some of the measurement values

  above should take into account that they pro-

  come from the conversion of Anglo-Saxon units into metric units.

  The present invention is not limited to the examples

  ples of realization which have just been described, it is on the contrary susceptible of variants and modifications

  which will appear to those skilled in the art.

13.

Claims (4)

  1 - Substrate having a deposit of metallic white palladium, characterized in that the deposit of palladium   metallic is smooth and substantially free of heavy deposits   dritic and in that it has an average value of reflectivity of white light, determined by means   spectrophotometric, ranging from around 78 to 95% of the   their average reflectance of white light of metallic rhodium measured for the same lengths wave.   2 - Substrate according to claim 1, characterized in that the light reflecting power values are   measured spectrophotometrically on an al- lant from 400 to 700 nanometers.   3 - Substrate according to claim 1, character-   in that the deposit has a thickness of about 0.01 to 1.0 micron.   4 - Substrate according to claim 3, character-   dried in that the deposit has a thickness of about 0.03 to 0.4 micron.