Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/22—Electroplating: Baths therefor from solutions of zinc
  • C25D3/24—Electroplating: Baths therefor from solutions of zinc from cyanide baths
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/22—Electroplating: Baths therefor from solutions of zinc

Definitions

• R is alkyl, alkenyl or alkynyl of 1 to 4 carbon atoms, benzyl and substituted benzyl wherein the substituent is at least one of alkyl of 1 to 4 carbon atoms, halogen, cyanide, alkoxy of 1 to 4 carbon atoms, phenyl and or a hydrohalide salt thereof,
• the weight ratio of polyethylenimine to quaternary pyridine compound being within the range of :1 to 1:100.
• the electroplating bath has a weight ratio of cyanide to zinc within the range of 0.1-3.5: 1, preferably about 1:1.
• This invention relates to zinc electroplating baths and processes and more particularly to alkaline, cyamde zinc electroplating baths and processes.
• R is alkyl, alkenyl or alkynyl of 1 to 4 carbon atoms, benzyl and substituted benzyl wherein the substituent is at least one of alkyl of 1 to 4 carbon atoms, halogen, cyanide, alkoxy of 1 to 4 carbon atoms, phenyl and or a hydrohalide salt thereof,
• the weight ratio of polyethylenimine to quaternary pyridine compound being within the range of 10:1 to 1:100 and said bath having a weight ratio of cyanide to zinc within the range of 0.1-3.5: 1.
• an aqueous addition agent for an alkaline electroplating bath consisting essentially of an aqueous solution at a pH between 4.5 and 8 of a combination of polyethylenimine having a molecular Weight between about 600 and 60,000 and a quaternary pyridine compound of the formula:
• R is alkyl, alkenyl or alkynyl of 1 to 4 carbon atoms, benzyl and substituted benzyl wherein the substituent is at least one of alkyl of 1 to 4 carbon atoms, halogen, cyanide, alkoxy of 1 to 4 carbon atoms, phenor a hydrohalide salt thereof,
• the weight ratio of polyethylenimine to quaternary pyridine compound being within the range of 10:1 to 1:100, said combination being at a concentration in solution of between 1 and 50 percent by weight.
• the polyethylenimine useful in the plating bath has a erably at about 1 to 30 percent by weight.
• weights below 600 and about 60,000 may also be empH of the aqueous solution should be between about 4.5 ployed, although those below 600 are not generally availand 8.
• pH outside this range the quaternary pyridine able commercially while those much over 60,000 are not 5 compound will tend to precipitate or the solution will be sufficiently soluble to be generally useful.
• a preferred pH range is 5.5 to 7.
• Poly- The plating bath is operated according to normal proethylenimine is added to the bath to give a concentration cedures using a sodium cyanide concentration within the of 0.005 to 2 grams per liter, preferably 0.02 to 0.2 gram range of about 5 to 45 grams per liter, preferably 5 to 20 per liter for barrel plating and 0.05 to 0.5 gram per liter grams per liter, and most preferably about 7 grams per for rack plating.
• liter and a zinc concentration about 5 to 20 grams per The quaternary pyridine compounds useful in the liter, and most preferably about 7 grams per liter.
• the higher cyanide concentrations are employed in high cyanide plating baths and the present brightening system is effective at these concentrations to enable the electroplater to convert his bath to lower cyanide levels, i.e., in the range of about 5 to grams per liter.
• the weight ratio of cyanide R to zinc should be in the range of about 0.1-3.5 :1, prefwherein R is alkyl, alkenyl, or alkynyl of 1 to 4 carbon 20 erably about 1:1 to 2:1 at the low cyanide levels.
• Plating atoms, benzyl and substituted benzyl wherein the ubbath temperatures will usually be between 20 and 40 C.
• stituent is at least one of alkyl of 1 to 4 carbon atoms, however, the brightening system can provide bright dehalogen, cyanide, alkoxy of 1 to 4 carbon atoms, phenyl posits over a wide current density range at temperatures and up 10 55 C-
• bath-soluble polymers may be added to the CHz-N plating bath in particular situations to give further improvements in operation.
• polyvinyl alcohol 00- or an oxidized polyvinyl alcohol can be used to replace or a hydrohalide salt ther of, a portion of the polyethylenimine in rack plating to give improved brightness to the zinc deposit.
• the brightening system of the present invention has the pyridinium 3-Carb0XYlat and y pyridinium advantages of good shelf life, good chemical stability in boxylate
• other compounds which may be used are 1-(4- the plating bath and a wide operating range so that the methylbenlyl) pyridinium 3-cafboxylflte, 'M- electroplater can make a running conversion from a high y pyridinium 3-carb0Xy1ate, y pyridinium cyanide bath to a low cyanide bath without affecting the carboxylate, and l-propargyl pyridinium 3-carboxylate. uality of the plating work.
• Thfise Compounds can also be Used as the hy r h l
• the invention can be further understood by referring salts such as hydrochloride or hydrobromide.
• salts such as hydrochloride or hydrobromide.
• the quatert th following examples in which parts and percentages nary pyridine compound is added to the bath to give are b weight unl other i indi t d,
• G A ratio used will depend upon the type of plating operation employed, the temperature of operation and the concen- Zn metaufmm Zno) tration of the bath. Generally, when the concentration of Sodium cyamdq the bath increases the Wei ht ratio will shift to hi her Sdmm hydmxlde 75 g g Sodium carbonate 52 concentrations of the quaternary pyridine compound.
• the combination of brightening ingredients used are Hull Cell panels were plated at 25 C. for 5 minutes at preferably used in the form of aqueous addition agents for 2 amps. using combinations of polyethylenimine and a zinc electroplating baths.
• Additives for the plating baths quaternary pyridine compound as brighteners in the stock can be prepared by dissolving the polyethylenimine and 55 solution. Each panel was bright-dipped in dilute nitric quaternary pyridine compound at the desired ratio at a acid before examination. The brightener added and results solids content of about 1 to 50 percent by weight, prefare shown in Table I.
• h drNgrE.1$PO 1-benzy1pyridiniiun 3-carb0xylate
• PEI Polyethy1enimine
• qnethyl BPC l -(4,-methylbenzyl) pryidinium a-carbogylate y 0 tom 0.
• Hull Cell panels were plated for 5 minutes at 2 amps. at 25 C., 35 C. and 45 C. from a plating bath of the following composition:
• R is alkyl, alkenyl or alkynyl of 1 to 4 carbon atoms, benzyl and substituted benzyl wherein the substituent is at least one of alkyl of 1 to 4 carbon atoms, halogen, cyanide, alkoxy of 1 to 4 carbon atoms, phenyl and war I about 600 and 1800 which is at a concentration within the range of 0.005 to 2 grams per liter.
• an aqueous alkaline cyanide zinc electroplating bath comprising: having added to said bath a combination of polyethylenimine having a molecular weight within the range of about 600 and 1800 and l-benzyl pyridinium 3-carboxylate, at a weight ratio within the range of about 1:1 to 1:20 and each at a concentration within the range of about 0.02 to 0.5 gram per liter, said bath having a weight ratio of cyanide to zinc of 1:1 at a cyanide concentration as sodium cyanide of about 5 to 20 grams per liter.
• R is alkyl, alkenyl or alkynyl of 1 to 4 carbon atoms, benzyl and substituted benzyl wherein the substituent'is at least one of alkyl of 1 to 4 carbon atoms, halogen, cyanide, alkoxy of 1 to 4 carbon atoms,
• the weight ratio of polyethylenimine to quaternary pyridine compound being within the range of 10:1 to 1:100, maintaining said bath at a weight ratio of cyanide to zinc within the range of 0.1-3.5 :1, and said polyethylenirnine being at a concentration within the range of 0.005 to 2 grams per liter.
• An aqueous addition agent for an alkaline electroplating bath consisting essentially of an aqueous solution at a pH between 4.5 and 8 of a combination of polyethylenimine having a molecular weight between about 600 and 60,000 and a quaternary pyridine compound of the formula:
• R is alkyl, alkenyl or alkynyl of 1 to 4 carbon atoms, benzyl and substituted benzyl wherein the substituent is at least one of alkyl of 1 to 4 carbon atoms, halogen, cyanide, alkoxy of 1 to 4 carbon atoms, phenyl and COO- 15.
• the aqueous addition agent of claim 15 wherein the polyethylenimine molecular weight is within the range of about 600 and 1800.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Electroplating And Plating Baths Therefor (AREA)

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Cited By (4)

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• 1971
  • 1971-09-30 US US00185348A patent/US3734839A/en not_active Expired - Lifetime
• 1972
  • 1972-09-25 CA CA152,483A patent/CA995620A/en not_active Expired
  • 1972-09-28 FR FR7234350A patent/FR2154685B1/fr not_active Expired
  • 1972-09-29 IT IT29888/72A patent/IT968456B/it active
  • 1972-09-29 GB GB4513272A patent/GB1358371A/en not_active Expired
  • 1972-09-30 JP JP9857172A patent/JPS549578B2/ja not_active Expired
• 1976
  • 1976-01-09 SE SE7600163A patent/SE7600163L/xx unknown

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