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

• Certain (hetero) aromatic unsaturated ketones have long been known as effective top gloss agents in acidic galvanic zinc baths. It is disadvantageous, however, that this class of compounds has melting points of mostly below 80 ° C., often below 50 ° C., which makes processing and metering difficult.
• the main product used in this class of compounds is benzalacetone, as is apparent, for example, from GB-PS 1 149 106 or US-PS 4 049 510. This compound has a melting point of 39 o to 41 0 C. Small impurities can also push the melting point below.
• the aim of the invention was a dosable form for the above ketones, by the measures the discovery - causes not show named disadvantages, and at least the same in galvanic acidic zinc baths effects, such as the product used in non-emulsified form. This goal has been achieved with aqueous emulsions as defined in claims 1 to 5.
• the emulsions according to the invention have proven to be stable at higher and lower temperatures. As a result, they can be delivered directly from the manufacturer to the end user, who can then meter them into the galvanic baths without any effort.
• the emulsions are prepared in a simple manner by emulsifying the ketone of the formula I in the molten state, expediently at 40 ° to 80 ° C. in water and in the presence of the emulsifier according to the definition, and allowing the emulsion formed to cool.
• Suitable ketones are compounds of the general formula I, it being essential that the melting point of the ketone to be emulsified is below 80 ° C., preferably below 50 ° C.
• the following ketones are considered as preferred ketones:
• emulsifiers are 30- to 70-fold ethoxylated, optionally hydrogenated castor oil and / or nonionic surfactants of the formula II A is therein an ethylene oxide or 1,2-propylene oxide radical and n is preferably 10 to 60. It is preferably an ethylene oxide radical. n depends on the number of carbon atoms in the radical R, a ratio of the number of carbon atoms in R to the number of carbon atoms in the alkylene oxide units of 1: 1 to 1: 8 being chosen.
• R represents an alkylphenyl radical as defined, the alkyl and phenyl carbon atoms are added together when determining this ratio.
• R is C 8 to C 20 alkyl, preferably C 9 to C 18 alkyl.
• Alkoxylates of n-decanol, dodecanol, tridecanol, natural fatty alcohols, octadecanol and mixtures thereof and then of synthetic alcohol mixtures such as C 9 / C 11 and C 13 / C 15 -C 16 / C 18 oxo alcohols may be mentioned as particularly preferred .
• RC 4 further denotes C 12 -alkylphenyl, preferably the octyl, nonyl or dodecylphenyl radical.
• R also means a saturated or unsaturated acyl radical having 8 to 20 carbon atoms.
• the surfactants should be present as a mixture in which the aforementioned ethoxylate is present in a maximum of 50% by weight.
• the rest preferably consists of surfactants in which RC is 8 to C 20 alkyl or C 4 to C 12 alkylphenyl.
• the emulsions according to the invention preferably contain 5 to 60, especially 15 to 50% by weight of the ketone and 1 to 30, especially more than 5% by weight of the emulsifiers, in each case based on the emulsions.
• the rest is water, which is preferably fully desalinated.
• the emulsions according to the invention can easily be added to acidic galvanic zinc baths. It has been shown that the emulsions achieve at least as good galvanizing as with the corresponding ketone, which was used in the previous form, but often also better in terms of gloss, since the emulsifier used itself has a positive effect in the bath with regard to ductility that can cause coatings.
• the emulsions are generally added to the zinc baths in an amount such that the baths contain 0.1 to 2.0 g / l of ketone.
• mixtures are also effective, and in some cases even increases in the stability of the emulsions can be achieved.
• at least 50% by weight, based on the mixtures, of surfactants which are 10 to 60 times ethoxylated are preferably present in the mixtures.
• the acidic galvanic zinc baths otherwise contain the usual additives. They contain e.g. 50 to 150 g / 1 zinc chloride or the equivalent amount of zinc sulfate, 100 to 250 g / l potassium chloride, 15 to 25 g / 1 boric acid, 1 to 8 g / 1 sodium benzoate and often 1 to 4 g / l naphthalenesulfonic acid / formaldehyde condensation products .
• nonionic surfactants can also be used; However, this addition is not always necessary, since the emulsions according to the invention are by definition based on nonionic surfactants. Use will be necessary if the emulsions have very low emulsifier contents.
• the zinc baths should expediently contain a total amount of 4 to 15 g / l of nonionic surfactants.
• Certain acidic zinc baths can also contain 10 to 100 g / l ammonium chloride or NaCl and 1 to 10 g / l polyethyleneimine.
• a certain amount of water is introduced and a mixture of a certain amount of surfactant and ketone benzalacetone is added at 50 ° C. After stirring for 5 minutes, the emulsion is left to stand and its stability is assessed at different storage temperatures at intervals of 24 hours each. A time interval is called "cycle" in the following.
• An emulsion is considered to be sufficiently stable if it has a grade of 3 over more than 2 cycles.
• a sheet 1 is run for 10 minutes in the Hull cell with 1A.
• a plate 2 (comparison) is also run for 10 minutes in the Hull cell with 1A, but 4 ml / l of a 10% benzalacetone solution in methanol are added to the bath.
• Sheet 1 has a uniformly glossy surface from the high to the low current density range. The coating is more even and ductile than with sheet 2.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
• Colloid Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Electroplating And Plating Baths Therefor (AREA)
• Cosmetics (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6167699

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (1)

Citations (2)

• 1982
  • 1982-07-06 DE DE19823225156 patent/DE3225156A1/de not_active Withdrawn
• 1983
  • 1983-06-25 EP EP83106206A patent/EP0098487A3/fr not_active Withdrawn
  • 1983-07-04 JP JP58120426A patent/JPS5920487A/ja active Pending

Patent Citations (2)

Also Published As

Similar Documents

Legal Events