Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/31—Coating with metals
  • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
  • C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents
  • C23C18/36—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents using hypophosphites
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S516/00—Colloid systems and wetting agents; subcombinations thereof; processes of
  • Y10S516/01—Wetting, emulsifying, dispersing, or stabilizing agents

Definitions

• a process for the chemical nickel-plating of articles which have a catalytic" surface has been described in German Pat. 1,077,940.
• the process substantially comprises treating the articles by means of a bath containing nickel and hypophosphite ions.
• catalytic as used in this context is intended to mean that at least the material forming the article surface is capable of catalyzing the oxido-reduction between the nickel ions and the hypophosphite ions, that causes the nickel to precipitate on the catalytic surface.
• the bath is primarily required to contain the reactants in specific proportions, i.e. the bath is required to contain:
• Ni and l-l,PO ions in a quantitative ratio between 0.25 and 1.60to contain H,P0, in an absolute concentration between 0.15 and 1.20 mols/liter; and to have a pl-l-value between 4.3 and 6,8, which is maintained by means of a buffer present therein and by the addition of alkali during the reaction.
• the bath is required to contain so-called activating agents formed of saturated, aliphatic dicarboxylic acids having three to six carbon atoms, such as succinic acid.
• the reaction is finally required to be carried out at a temperature between 95 and 99 C.
• the surface of nonmetallic articles can be treated to receive, for example, a metallic nickel-plating.
• the article is firstcleaned to activate its surface which is roughened thereafter, and pretreated by means of a palladium salt solution.
• the palladium chloride is reduced to palladium and the article so activated is immersed thereafter in a bath containing nickel and hypophosphite ions.
• the palladium chloride solution suitable for surface activation preferably has concentration of 35 milli-grarns per liter.
• hypophosphite is the reducing agent, it is advantageous to dissolve it in the metallization bath in a concentration of 0.225 mol/liter.
• the palladium-activated article should preferably be nickelplated first with the use of a dilute preliminary bath containing Ni and H,PO, in a molar ratio of about 0.25 and, after formation of a continuous nickel plating, the article should be treated further by means of a bath customary in nickel-plating.
• the preliminary nickel-plating bath is said to avoid the induction period usually needed for the nickel to precipitate on the dispersed palladium particles as the growth-promoting nuclei, and to improve the bond strength of the nickel plating.
• the preliminary nickel-plating bath can contain, for example, the following components:
• the preliminary bath used in carrying out the nickel-plating should have a pH-value between 5.5 and 7 and a temperature between 10 and 30 C.
• the bath can be used in combination with an ordinatherewith, in the suggested temperature range of 10 to 30 C., so that a layer not thicker than 1 to 1.2 p. is produced per hour. 1n the event that the temperature is increased to a value higher than 30 C., the preliminary nickel-plating bath is found to undergo spontaneous self-decomposition with the resultant formation of colloidal nickel, and to become useless.
• German Pat. 1,077,940 mentioned above' is not applicable to thedirect nickel-plating of nonmetallic articles, for example plastics.
• reasons for this are that thermoplastics, for example, undergo plastic deformation at a temperature of -99 C. needed for the nickel-plating bath, and that the precipitated layer of nickel would be foundto have a poor bond strength.
• This process for the chemical nickel-plating of nonmetallic articles which are (a) cleaned by mechanicaland/or chemical treatment, (b) activated thereafter by means of'an aqueous palladium salt solution, of which the palladium salt is reduced to palladium, and (c) immersed in a preheated nickel-plating bath,which contains nickel and hypophosphite ions and a buffer substance and is maintained at a pl-l-valuebetween '3 and 9, comprises nickel-plating the said articles using a nickelplating bath containing nitrilotrismethylene-phosphonic acid as an additional component and heated to a temperature between 30 and 70 C.
• the nickel-plating bath contains Ni"-ions and nitrilo-trismethylene-phosphonic acid in a molar ratio between 0.7 and 2.0.
• a phosphate buffer containing, per liter, 0.02 to 0.1 mol, preferably 0.067 mol Na,HPO 211,0, and 0.002 to 0.1 mol, preferably 0.0067 mol Kl-LPO has proved very suitable for maintaining the above pl-l-values.
• the phosphate buffer is found to participate in the stabilization of the bath, at the pH- values indicated above.
• pH-values and temperatures higher than those specified above accelerate the precipitation of nickel, but they reduce the stability of the bath and impair the bond strength of the nickel plating. ln the case of a bath having a pl-l-value higher than 7, it is possible further to increase the baths stability in conventional manner by the addition of a stabilizer, such as lead sulfide or lead acetate, which is used in a proportion of 2 milligrams per liter.
• a stabilizer such as lead sulfide or lead acetate
• the nickel is found to precipitate uniformly per unit of time on the surface of the article. 1n view of the fact that the nickel-plating bath having the above composition practically needs no induction period for the nickel to commence precipitation, it is clear that the articles dipped in the nickel-plating bath are completely metallized after no more than 15 seconds. After 2 to 3 minutes, the precipitated nickel plating has a thickness of about 3 to 3.5 u.
• the nickel plating which is really formed of a nickel-phosphorus alloy containing 5 to percent phosphorus, adheres very tenaciously to nonmetallic articles of which the surface has been activated in convenient manner, prior to the metallization.
• the nickel plating precipitated by the process of Pat. Application No. 651,968, can be reinforced by means of electrodeposited nickel, polishednickel and polished chromium coatings, or may receive a ductile copper coating as a first reinforcing coating.
• the pretreatment of the article to be plated in an attempt to activate its surface can be carried out, for example, in the manner set forth in German Pat. 1,182,015.
• nitrilo-trismethylene phosphonic acid means high precipitation velocity for the nickel at temperatures of the nickel-plating bath between 30 and 70 C., so that nonmetallic articles pretreated in convenient fashion, can be metallized more rapidly than heretofore.
• the bath is very stable and therefore easy to manipulate.
• the bath used in carrying out the above nickel-plating process can be regenerated in customary manner by means of hypophosphite and nickel ions, for example by the process disclosed in German Pat. 1,107,045.
• the regeneration is very easy to achieve as there is no need for cooling the bath liquid prior to the addition of the regenerating agent.
• the present process for the chemical nickel-plating of nonmetallic articles carried out in accordance with U.S. Pat. No. 3,506,802, wherein the articles are (a) cleaned by mechanical and/or chemical treatment, (b) activated later by means of an aqueous palladium salt solution, of which the palladium salt is reduced to palladium, and (c) immersed in a nickel-plating bath, which is preheated to a temperature between about 30 and 70 G, contains nickel and hypophosphite ions, one or more buffer substances and phosphonic acid compounds, and is maintained at a pH-value between 3 and 9, comprises more especially carrying out the nickel-plating with the use of a nickel-plating bath containing one or more phosphonic acid compounds corresponding to either the following general form alllL- A Rg-CXY in which X and Y stand for hydrogen atom or an alkyl group having one to six carbon atoms, R, and R, stand for a JO H;- group or a -C0Ol
• a W P 03H (Jill in which 2 stands for a hydrogen atom, an -OH-group or -HN,- group and R stands for a hydrogen atom or an alkyl group having one to six carbon atoms or stands for a group corresponding to the following formula (IV) CXY-Rl CXY-Rs in which formula (IV) X and Y stand for a hydrogen atom or an alkyl group having 1 to 6 carbon atoms and R and R, stand for a -PO H -group, a -COOl-l-group or a -COOH-group and a -PO H -group.
• the Ni-ions and the phosphonic acid compound are preferably used in a molar ratio between about 0.7 and 2.0.
• the phosphonic acid compounds suitable for use in the present process include, for example: ethylene-diamineteu'amethylene phosphonic acid; nitrilo-monoacetic aciddimethylene phosphonic acid; ethylene-diamine-diacetic aciddimethylene phosphonic acid; l-hydroxyethanel diphosphonic acid; ethylene-l-aminodimethylene phosphonic acid-2-hydroxy-2,Z-diphosphonic acid, which can be used.
• F u rther jnt er e s ting compounds include: ethylene-l-amino-diacetic acid-2,2-diphosphonic acid; ethylene-l-amino-diacetic acid-2-amino-2,2-diphosphonic acid.
• the amino-diacetic acid-substituent can be replaced in each particular case by an amino-group, which has an acetic acid radical as well as a methylene phosphonic acid gdical linkgd the gtg 'mckel-plating bath containing one or more of the above phosphonic acid compounds enables the same advantageous effects as those produced by the process described in U.S. Pat. No.
• EXAMPLE 1 Shaped plastics obtained by graft polymerization of acrylonitrile, butadiene and styrene were chemically nickelplated. Prior to being nickel-plated, their surfaces had been cleaned and degreased by means of an aqueous solution of a commercial surface-active substance, chemically roughened later at 60 C. for 15 minutes with the use of chromosulfuric acid, and ultimately sensitized with an aqueous tin chloride solution in hydrochloric acid. Thereafter, the surfaces of the shapes had been activated by means of a PdCl solution in hydrochloric acid.
• the shaped plastics were nickel-plated by means of a nickel-plating bath prepared in accordance with the present invention, the bath containing:
• the bath was adjusted by means of sodium hydroxide solution to have a pH-value of 6.0 and heated to 50 C.
• the shapes clamped to insulated holders, were dipped in the slightly agitated bath liquid. A continuous, well-adhering nickelplating was found to have precipitated on the shapes within a period of seconds, which, after a further 3 minutes, was found to be capable of being electro-plated.
• EXAMPLE 2 Modified polypropylene shapes were pretreated in a manner analogous to that described in example 1. The nickelplating was carried out using a nickel-plating bath containing:
• NiSO,-7H,0 0.11 moi/liter NaH,PO,-H,O 0.28 mol/liter nitrilo-monoacetic acid-dimethylene phosphonic acid 0.13 mol/liter Na,HPO,2H,O 0.067 mol/liter KH,P0, 0.0067 mol/liter bath temperature 60 C.
• a continuous, well-adhering nickel plating was found to have precipitated on the shapes within a period of 20 seconds, which, after a further 3 minutes, was found to be capable of being electro-plated.
• the shaped plastics were nickel-plated by means of a nickel-plating bath prepared in accordance with the present invention, the bath containing:
• the bath was adjusted by means of sodium hdyroxide solution to have a pH-value of 6.5 and heated to 45 C.
• the shapes clamped to insulated holders, were dipped in the slightly agitated bath liquid.
• a continuous, well-adhering nickel plating was found to have precipitated on the shapes within a period of 20 seconds, which, after a further 3 minutes, was found to be capable of being electroplated.
• EXAMPLE 4 Modified polypropylene shapes were pretreated in a manner analogous to that described in example 3. The shapes were roughened at C. within a period of 20 minutes by means of chromosulfuric acid. The nickel plating was carried out using a nickel-plating bath containing:
• a continuous, well-adhering nickel plating was found to have precipitated on the shapes within a period of 20 seconds, which, after a further 3 minutes, was found to be capable of being electro-plated.

Landscapes

• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemically Coating (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=27180923

Family Applications (1)

Country Status (3)

Cited By (14)

Citations (4)

• 0
  • FR FRJ8061696*8A patent/FR96342E/fr not_active Expired
• 1968
  • 1968-10-29 US US771643A patent/US3617343A/en not_active Expired - Lifetime
  • 1968-11-12 GB GB53592/68A patent/GB1192678A/en not_active Expired

Patent Citations (4)

Also Published As

Similar Documents