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

Definitions

• ABSTRACT 30 Foreign Application p i Dam An aqueous acidic zinc bath is used for electroplating Sap I8 German 2346942 bright ductile metallic zinc deposits on metal suby strates. said plating bath containing at least one soluble zinc compound capable of being plated by electroliil a?SIJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ: b52352; We depogfion a or a Poly;
• the present invention relates to an acid plating bath for depositing metallic zinc on a substrate in which the zinc deposit produced thereby is ductile and presents a glossy to bright coating on the substrate over a wide cathodic current density range.
• the ductility of the bright coatings deposited from heretofore known acid zinc baths is distinctly lower than the coatings from alkaline baths.
• Several patents relating to the deposition of bright zinc coatings from acid baths state that their processes permit the deposi tion of ductile zinc coatings. Measurement of the breaking elongation of zinc layers obtained from such baths, as an index of their ductility, shows differences between the results of the particular processes. but also show that the breaking elongation in all cases is under 1.0%.
• the breaking elongation is defined as the percent that the length of the electroplated substrate may be increased before the zinc coating thereon develops cracks or fissures.
• the ethylene oxide portion amounts to 30 to
• the additional surface-active compounds of the patent include N-(alkylsulfonyl )-glycine and imidazoline derivatives and the baths also contain ammonium salts.
• the object of the present invention is to obtain an acid plating bath of the type defined above which is free of the aforesaid disadvantages and in particular makes possible the deposition of bright zinc layers with greater ductility.
• ammonium salts are not necessary and they may be replaced by simple salts of sodium or potassium.
• Ammonium salts may. however. continue to be used and. moreover. mixed alkali salts. optionally together with ammonium salts. may also be used.
• the present invention thus makes it possible to use acid bright zinc baths having none or only a very small portion of ammonium salts. This procedure eliminates the above-mentioned difficulties inherent in the treatment of waste waters of acid bright zinc baths that have a high content of ammonium salts.
• Baths pursuant to the present invention have the further advantage of showing no or only very little formation of froth. thus avoiding the possible resultant difficulties in the use of air injection for increased pro- 3 duction as described above.
• the polymerization products used pursuant to the present invention vary in their solubility within the bath. Their solubility may, however, be adjusted to meet the bath requirements. In general their solubility decreases with increasing molecular weight and in creases with increasing content of ethylene oxide. Additionally, the polymerization products not sufficiently soluble in the bath may nevertheless be used if they are emulsified by an emulsifier compatible with the bath and in sufficient quantity in the bath.
• Baths pursuant to the present invention yield zinc coatings whose ductility is better than that of acid baths known heretofore. They in all cases lie within the limits given above, i.e., a breaking elongation of up to 3%.
• the most ductile coatings are obtained with baths pursuant to the invention with interpolymers of propylene oxide and ethylene oxide having an ethylene oxide content of to
• the polypropoxy ethers and the polypropoxy-ethoxy ethers can be used alone or in mixture with each other, and are the polymerization products of propylene oxide and/or propylene oxide and ethylene oxide. These products are well known and can also be prepared in manners well known in the art.
• the polymerization products, polypropoxy ethers and/or polypropoxy-ethoxy ethers, incorporated in baths pursuant to the invention, are used in quantities of 1 g/l up to the limit of solubility or emulsifiability in the bath, preferably however, in quantities of approximately 3 to 20 g/l.
• These polymerization products have, in the case. of the polypropoxy ethers, a molecular weight of advantageously between about 300 and 1500, and in the case of the polypropoxy-ethoxy ethers interpolymers a molecular weight of advantageously be' tween about 1000 and 5000.
• emulsifiers may be used with the bath composition to colloidally suspend the polymerization products in the bath solution.
• the emulsifiers used should, of course, be sufficiently soluble in the bath and compatible with the remaining bath constituents and have sufficient emulsifying capacity for the polymerization products used in each case. They may be anionic, non-ionic, amphoteric or cationic. Particularly suitable are anionic boundary surface-active substances such as alkyl sulfates, alkyl sulfonates, alkyl-substituted diphenyl oxide sulfonates and sulfated polyglycol ethers. How ever, nonionic, amphoteric or cationic boundary surface-active substances, if they are compatible with the bath, may also be used.
• emulsifiers such as, for example, condensation products of naphthalene sulfonic acid and formalin are also usable.
• emulsifiers which themselves have only a relatively small frothing capacity or whose frothing capacity is largely inhibited by the defrothing effect of the polymerization products used pursuant to the invention.
• the quantity of emulsifier used depends upon the type and quantity of the condensation products used and upon its emulsifying capacity. It is in general be tween about l and 20 g/l.
• the preferred zinc compounds include the customarily water-soluble zinc compounds and are employed in the usual quantities well known in the art.
• Zinc chloride. zinc nitrate, zinc acetate, zinc fluoroborate and zinc sulfate are preferable.
• Alkali salts that may be used the simple salts of sodium, potassium or ammonium, include the sulfates, chlorides, fluoroborates, acetates alone or in mixtures.
• the alkali salts are used in quantities of from about 5 to about 250 g/l, preferably in quantities of about 20 to about 180 g/l.
• conventional brightening agents may be included in the bath such as carbonyl compounds which are well known in the art. More specifically, brightening agents which can be used in the baths include aromatic carbonyl compounds, aldehydes, ketones or salts of carboxylic acids. Ketones preferably are used and benzal acetone is a particularly acceptable ketone. Particularly good brightness within a wide cathodic current density range can be obtained in many cases if two or more carbonyl compounds are used simultaneously, of which one is the salt of an aromatic carboxylic acid, such as sodium benzoate.
• the aldehydes and ketones are used in quantities of between about 0.05 and 3 g/l, the salts of aromatic carboxylic acids in quantities of between about 1 and 20 g/l.
• Baths pursuant to the present invention can be used with agitation, preferably mechanically or by air.
• the electrolytic deposition can be carried out at a pH of between about 3 and 6, preferably from between about 4 and 5.8, and within a temperature range of between about 15 and 30C.
• cathodic current densities of up to SA/dm may be attained. 1f the baths are operated by air flow, then even considerably higher cathodic current densities are possible.
• the bath compositions listed below yield in an aque ous bath at a temperature of 20 to 25C., within wide cathodic current density range, preferably at current densities of 3 A/dm, and pH within a range of 4 to 5.5 with moderate bath agitation and exposure times of 10 to 15 minutes, bright to very bright zinc deposition.
• Non-ionic surface-active compound of isononyl alcohol and approximately l5 mols ethylene oxide isononyl alcohol and approximately l5 mols ethylene oxide.
• An aqueous acid zinc plating bath substantially void of ammonium ions for depositing ductile glossy to bright zinc layers within a wide cathodic current density range containing a water-soluble zinc compound capable of plating zinc metal on a substrate at least about 1 g/l of a polypropoxy ether having a molecular weight of from about 300 to about l500 and/or a polypropoxy-ethoxy ether having a molecular weight of from about 1,000 to about 5,000 and containing up to about 25% by weight of the polymer of the oxyethylene moiety and an aromatic carbonyl compound.
• An aqueous acid zinc plating bath according to claim 1 in which the polymer is present in an amount from about 1 g/l to its limit of solubility.
• An aqueous acid zinc plating bath according to claim 1 in which the polymer is insoluble in the baths or exceeds the solubility of the polymer in the bath, and in which the polymer is emulsified with an emulsifying agent.
• the surface active emulsifying agents include the sodium salt of decyloxydiphenyldisulfonic acid; the condensation product of naphthalene sulfonic acid and formalin; oleylamine having 6 to 7 mols of ethylene oxide attached thereto and quaternized with dimethyl sulfate; isononyl alcohol having mols of ethylene oxide attached thereto; the sodium salt of dodecyloxydiphenyl disulfonic acid; ethylhexyl sulfate C -C sulfated aliphatic alcohols having from 70 to 90 mols of ethylene oxide attached thereto or dodecane amidobetaine.
• the surface active emulsifying agents include the sodium salt of decyloxydiphenyldisulfonic acid; the condensation product of naphthalene sulfonic acid and formalin; oleylamine having 6 to 7 mols of ethylene oxide attached thereto and quaternized with dimethyl
• An aqueous acid zinc plating bath according to claim 1 which contains a mixture of benzal acetone and sodium benzoate a brightening agent.
• An aqueous acid zinc plating bath for depositing ductile glossy to bright zinc layers within a wide cathodic current density range containing a water-soluble zinc compound capable of plating zinc metal on a substrate and a polypropoxy-ethoxy ether having an approximate molecular weight of between about L000 to about 5 .000 and containing up to about 25% by weight of the polymer of the oxyethylene moiety, said polymer being present in an amount of at least about l g/l.
• An aqueous acid zinc plating bath according to claim 9 in which the polymer is insoluble in the bath or exceeds the solubility of the polymer in the bath and in which the polymer is emulsified with an emulsifying agent.
• emulsifying agents include the sodium salt of decyloxydiphenyl disulfonic acid; the condensation product of naphthalene sulfonic acid and formalin; oleylamine having 6 to 7 mols of ethylene oxide attached thereto and quaternized with dimethyl sulfate; isononyl alcohol having 15 mols of ethylene oxide attached thereto; the sodium salt of dodecyloxydiphenyl disulfonic acid; ethylhexyl sulfate C C sulfated aliphatic alcohols having from to mols of ethylene oxide attached thereto or dodecane amidobetaine.
• An aqueous acid zinc plating bath according to claim 9 which includes a brightening agent comprising one or more aromatic carbonyl compounds.

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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)
• Electroplating And Plating Baths Therefor (AREA)
• Cosmetics (AREA)
• Detergent Compositions (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=5892951

Family Applications (1)

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Cited By (14)

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Citations (2)

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• 1973
  • 1973-09-18 DE DE2346942A patent/DE2346942C3/de not_active Expired
• 1974
  • 1974-07-31 CH CH1058074A patent/CH610015A5/xx not_active IP Right Cessation
  • 1974-08-08 AT AT648074A patent/AT331605B/de not_active IP Right Cessation
  • 1974-08-10 JP JP9191174A patent/JPS5413212B2/ja not_active Expired
  • 1974-08-10 ES ES429148A patent/ES429148A1/es not_active Expired
  • 1974-08-15 NL NL7410944A patent/NL7410944A/xx not_active Application Discontinuation
  • 1974-09-04 IT IT26919/74A patent/IT1030608B/it active
  • 1974-09-11 US US505065A patent/US3928149A/en not_active Expired - Lifetime
  • 1974-09-17 FR FR7431359A patent/FR2244020B1/fr not_active Expired
  • 1974-09-18 GB GB4073974A patent/GB1462725A/en not_active Expired

Patent Citations (2)

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