US2101580A - Process for obtaining bright zinc coating - Google Patents
Process for obtaining bright zinc coating Download PDFInfo
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- US2101580A US2101580A US77527A US7752736A US2101580A US 2101580 A US2101580 A US 2101580A US 77527 A US77527 A US 77527A US 7752736 A US7752736 A US 7752736A US 2101580 A US2101580 A US 2101580A
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- US
- United States
- Prior art keywords
- resin
- zinc
- cyanide
- ammonium thiocyanate
- bath
- Prior art date
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- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 title description 22
- 229910052725 zinc Inorganic materials 0.000 title description 22
- 239000011701 zinc Substances 0.000 title description 22
- 238000000034 method Methods 0.000 title description 9
- 239000011248 coating agent Substances 0.000 title 1
- 238000000576 coating method Methods 0.000 title 1
- 239000011347 resin Substances 0.000 description 39
- 229920005989 resin Polymers 0.000 description 39
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 30
- 238000007747 plating Methods 0.000 description 23
- -1 ammonium thiocyanate-formaldehyde Chemical compound 0.000 description 14
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 12
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 11
- 235000011121 sodium hydroxide Nutrition 0.000 description 10
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 6
- 239000002253 acid Substances 0.000 description 6
- 238000005282 brightening Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- 150000007513 acids Chemical class 0.000 description 4
- SOIFLUNRINLCBN-UHFFFAOYSA-N ammonium thiocyanate Chemical compound [NH4+].[S-]C#N SOIFLUNRINLCBN-UHFFFAOYSA-N 0.000 description 4
- VQLYBLABXAHUDN-UHFFFAOYSA-N bis(4-fluorophenyl)-methyl-(1,2,4-triazol-1-ylmethyl)silane;methyl n-(1h-benzimidazol-2-yl)carbamate Chemical compound C1=CC=C2NC(NC(=O)OC)=NC2=C1.C=1C=C(F)C=CC=1[Si](C=1C=CC(F)=CC=1)(C)CN1C=NC=N1 VQLYBLABXAHUDN-UHFFFAOYSA-N 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- 239000000320 mechanical mixture Substances 0.000 description 4
- 150000003751 zinc Chemical class 0.000 description 4
- GTLDTDOJJJZVBW-UHFFFAOYSA-N zinc cyanide Chemical compound [Zn+2].N#[C-].N#[C-] GTLDTDOJJJZVBW-UHFFFAOYSA-N 0.000 description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000001117 sulphuric acid Substances 0.000 description 3
- 235000011149 sulphuric acid Nutrition 0.000 description 3
- 239000011787 zinc oxide Substances 0.000 description 3
- QTWJRLJHJPIABL-UHFFFAOYSA-N 2-methylphenol;3-methylphenol;4-methylphenol Chemical compound CC1=CC=C(O)C=C1.CC1=CC=CC(O)=C1.CC1=CC=CC=C1O QTWJRLJHJPIABL-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 229910052793 cadmium Inorganic materials 0.000 description 2
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 2
- 229930003836 cresol Natural products 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical compound O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 description 2
- 159000000011 group IA salts Chemical class 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052753 mercury Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 235000007686 potassium Nutrition 0.000 description 2
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 235000015424 sodium Nutrition 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 235000002906 tartaric acid Nutrition 0.000 description 2
- 239000011975 tartaric acid Substances 0.000 description 2
- KJCVRFUGPWSIIH-UHFFFAOYSA-N 1-naphthol Chemical compound C1=CC=C2C(O)=CC=CC2=C1 KJCVRFUGPWSIIH-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- RSWGJHLUYNHPMX-ONCXSQPRSA-N abietic acid Chemical compound C([C@@H]12)CC(C(C)C)=CC1=CC[C@@H]1[C@]2(C)CCC[C@@]1(C)C(O)=O RSWGJHLUYNHPMX-ONCXSQPRSA-N 0.000 description 1
- 239000003377 acid catalyst Substances 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- MGJURKDLIJVDEO-UHFFFAOYSA-N formaldehyde;hydrate Chemical compound O.O=C MGJURKDLIJVDEO-UHFFFAOYSA-N 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 235000011056 potassium acetate Nutrition 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 235000011181 potassium carbonates Nutrition 0.000 description 1
- 235000011118 potassium hydroxide Nutrition 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- MNWBNISUBARLIT-UHFFFAOYSA-N sodium cyanide Chemical compound [Na+].N#[C-] MNWBNISUBARLIT-UHFFFAOYSA-N 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000006188 syrup Substances 0.000 description 1
- 235000020357 syrup Nutrition 0.000 description 1
- 229940100888 zinc compound Drugs 0.000 description 1
- 150000003752 zinc compounds Chemical class 0.000 description 1
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
Definitions
- This invention relates to electrodeposition of zinc, particularlyfrom an alkaline bath which has, or can be given, a bright lustrous appearance and to a composition of matter for forming such It has been found previously; that good zinc plates can be obtained only wh'enthe purity of the solution and the anodes are controlled. Such plates canbe bright dipped in solutions of chromic acid, United States Patent 2,021,592, to
- Another object of th'is invention is to produce zinc plating solutions which will tolerate higher amounts 'of impurities, particularly lead and produce bright or bright dip cadmium, and still pable plates.
- the decanted liquor contains. considerable amount of dissolvedbrightener. It may be used either together with the next batch or the dissolved resin may be precipitated by means of slowneutral ization with an acid such as dilute sulphuric acid.
- the total yield is approximately 30 lbs. of brightener. 1
- Purer chemicals may be used in the condensa- Jtlon butthe' ordinary technical grades are fully satisfactory and cheaper.
- causticl soda in the above reaction is'that of a catalyst.
- Any alkaline salt can be used for this purpose suchas caustic potash, sodium and potassium carbonate, sodium and potassium sulphocy'anate, cyanide of sodium or potassium, or sodium or potassium acetate, or
- the resin may also be solubilized in othermanners.
- I One gram .of the resin may be dissolved in 1 0,rnl.'of 66 ,B. sulphuric acid at room temperature. This mixtureispoured into a solution containing grams of sodium carbonate in 150. m liioi Water, which neutralizes the excess sulphuric acid, This v gives a flocculent, precip tate of asulphonated resin, which dissolves to the exgivesgood plate, although the lustre has been lessened slightly ,by'the sulphonation.
- Ten grams of the resin may be dissolved in 25 ml. of a solution containing 5 grams of urea, and the mixture boiled for 20, minutes. This gives a clear, yellow syrup which is completely dispers ible in the zinc bath and which gives a lustrous deposit.
- Another preferred formula comprises sang/1.
- the optimum concentration of the standard resin is between .5 and 1.0 g/l.
- Bright plates are obtained at 10 amp/sq. ft. and very brilliant plates at higher current densities.
- concentrations of brightener the plates tend to be streaky at low current densities; and at higher current densities the plates are not very bright, although there is a great deal of grain refinement.
- conccntrations only the low current density plates are bright while the plates obtained at higher current densities are ribbed or burned on the edges.
- solubility of ammonium thiocyanate formaldehyde resin in the plating bath is not critical.
- the brightening effect of the resin decreases with increasing solubility and vice versa the brightening effect of the resin increases with decreasing solubility of the resin.
- the greater the solubility of the resin the less brightening effect and the lesser the solubility of the resin the greater the brightening effect.
- the low current density plates are generally not as bright as the high current density plates, consequently the brightness of a deeply recessed part varies from the high current density points to the low current density points. If the concentration of brightener is too low, the lustre may not always be as high as desired and the plate may have a slightly brownish cast. 1 These difficulties are overcome by the use of bright dips, as mentioned above, whereby the lustre is equalized or increased. I
- the required concentration of brightener increases with increasing metal and caustic soda content in the bath and decreases with decreasing sodium cyanide content.
- the method of electrodepositing zinc comprising electrodepositing the said metal from a cyanide plating solution containing an ammonium thiocyanate formaldehyde resin which is soluble in the cyanide plating solution.
- the method of electrodepositing zinc comprising electrodepositing the said metal from a cyanide plating solution containing a solubilized ammonium thiocyanate formaldehyde resin.
- the method of electrodepositing zinc comprising electrodepositing said metal from a cyanide plating solution containing an ammonium thiocyanate formaldehyde resin formed by reacting ammonium thiocyanate and formaldehyde in the presence of a catalyst in the form of an alkaline salt.
- the method of electrodepositing zinc comprising electrodepositing said metal from a cyanide plating solution containing an ammonium thiocyanate formaldehyde resin formed by reacting ammonium thiocyanate and formaldehyde in the presence of a catalyst in the form of an acid.
- the method of electrodepositing zinc comprising electrodepositing the said metal from a plating bath consisting of a relatively pure cyanide solution and containing an ammonium thiocyanate formaldehyde resin which is soluble in the cyanide plating solution.
- the method of electrodepositing zinc comprising electrodepositing the said metal from a plating bath consisting of a relatively pure cyanide solution and containing an ammonium thiocyanate formaldehyde resin which is soluble in the plating bath and in the presence of a pure zinc anode.
- a plating bath for electrodepositing zinc comprising a cyanide solution of said metal and an ammonium thiocyanate formaldehyde resin soluble in the said cyanide solution.
- composition of matter comprising a me- 1 chanical mixture of zinc oxide, sodium cyanide,
- caustic soda caustic soda
- ammonium thiocyanate formaldehyde resin caustic soda, and ammonium thiocyanate formaldehyde resin.
- a compositionof matter comprising a mechanical mixture of zinc cyanide, caustic soda, sodium cyanide and ammonium thiocyanate formaldehyde resin.
- a composition of matter comprising a mechanical mixture of a zinc salt, caustic soda, sodium cyanide and ammonium thiocyanate formaldehyde resin.
Description
alkaline zinc plating solution.
Patented Dec. 7,. 1937 mm i. Henric'ks,
diana.
lite Company, Detroit, Mich, a corporation of I No Drawing. Application May 2, 1936,
. 7 Serial N0. 77,527
in Claims. (01. 204-18) i This invention relates to electrodeposition of zinc, particularlyfrom an alkaline bath which has, or can be given, a bright lustrous appearance and to a composition of matter for forming such It has been found previously; that good zinc plates can be obtained only wh'enthe purity of the solution and the anodes are controlled. Such plates canbe bright dipped in solutions of chromic acid, United States Patent 2,021,592, to
George Dubpernell and Karl Gustaf Soderberg and application Serial'No. 45,416 to the same inventors acidifled hydrogen peroxide application Serial No. 10,086 to Karl Gustaf Soderbe'rg, bro- .mic andiallied acids, Serial No. 21,276 to David B. Stockton, anddilute nitric acid, United States ture is then allowed Patent 1,816,837 to Carl L. Ganser. However, the plates obtained in this mannerare' not as lustrous as is sometimes desired; Thus, one object of this invention is to produce zinc plates whichhave a mirror-like lustre.
Ithas been found that plain zinc cyanide solutions are rather sensitive to impurities. Thus another object of th'is invention is to produce zinc plating solutions which will tolerate higher amounts 'of impurities, particularly lead and produce bright or bright dip cadmium, and still pable plates. w I
I have found that.these desirablejresults can be had by the addition to the zinc plating baths small amounts of ammonium thiocyanate-formaldehyde resins.
M These ammonium thiocyanate-formaldehyde:, resins can be manufactured according to any of" the processes heretofore known inthe art or 'according to the following preferred methods which I have originated. w
Twenty-five pounds of technical ammonium thiocyanate containinga minimum of 90% of NH4CNSis placed in a 30 gallon steel tank. 4% gallons of formaldehyde water solution, El technical, is carefully'added, with an exhaust-fan running, to minimizeobjectionable fumes; then is addedl lbs. of caustic soda. technical, and 2% lbs. of cresol, technical, and the mixture is thoroughly stirred with a wooden paddle. It is then boiled-for 20 minutes withintermittentstir ring. to keep the brightener from precipitating too heavily around the heater coils'. The mixw to cool'and when the super-& natant liquor has clarified it is decanted into as convenientreceptacle and the remaining bright-1 ener is allowed to dry and harden. It can then be removed fromthe tank and pulverized. The decanted liquor contains. considerable amount of dissolvedbrightener. It may be used either together with the next batch or the dissolved resin may be precipitated by means of slowneutral ization with an acid such as dilute sulphuric acid.
half pound tr tartaric acid tent 'of about.85%
The total yield is approximately 30 lbs. of brightener. 1
Purer chemicals may be used in the condensa- Jtlon butthe' ordinary technical grades are fully satisfactory and cheaper.
The function of the causticl soda in the above reaction is'that of a catalyst. Any alkaline salt can be used for this purpose suchas caustic potash, sodium and potassium carbonate, sodium and potassium sulphocy'anate, cyanide of sodium or potassium, or sodium or potassium acetate, or
, other alkali'salts of organic acids. The amounts requiredare proportional to the molecular weight of thesalt. n w One can also use an acid catalyst such as one- Proportional amountsflof citric-"oxalic, acetic, furoic, may also be used with equalsuccess, also small amounts of mineral acids. i 1 i The cresol is used for a 'solubilizer- ,It not only makes the resin more easily dispersiblein the. plating solution, but it also prevents the precipl-f tation of insoluble zinccompounds with the resin.
Inlts absence, the resin isslowly removed from the bath and gradually loses its effect. Among other si'milarcompounds which have proven satisfactory are-phenol and phenol-sulphonic acids, quinol; naphth'ol'and naphthol sulphonic acids.
'The resinmay also be solubilized in othermanners. I One gram .of the resin may be dissolved in 1 0,rnl.'of 66 ,B. sulphuric acid at room temperature. This mixtureispoured into a solution containing grams of sodium carbonate in 150. m liioi Water, which neutralizes the excess sulphuric acid, This v gives a flocculent, precip tate of asulphonated resin, which dissolves to the exgivesgood plate, although the lustre has been lessened slightly ,by'the sulphonation.
Ten grams of the resin may be dissolved in 25 ml. of a solution containing 5 grams of urea, and the mixture boiled for 20, minutes. This gives a clear, yellow syrup which is completely dispers ible in the zinc bath and which gives a lustrous deposit.
Another preferred formula comprises sang/1.
on boiling. Sulphonated resin of technical ammonium thiocyanate, 750 ml. of
37% of technical water solution of formaldehyde,
.7,5 ;gramsof tartaric acid. These three composiax. ture allowedto cool down to F. The mixture is kept at this temperaturei15il F.) for 20 tions are mixed and brought to boiling temperaminutes. About 400 grams-of yellow resin precipitates and can be separated by dec'antationi This resin whenadded to the zinc plating baths] suchas zinc cyanide plating baths, gave brilliant plates," the concentrations ranging fromn6 to .9 gram per liter. However, this resin was not solubilized, and althoughit ,worked very well forthr or four days, at the end of such time part of the resin had precipitated and fallen to the bottom of the bath thereby requiring the addition of more resin to bring the bath into optimum operating condition.
In testing the brightening effect of these resins, I used a zinc solution containing 4.5 oz./gal. of zinc, 9 oz./gal. of total cyanide, expressed as sodium cyanide, and 10 oz./gal. of total caustic soda. This bath had been prepared from a pharmaceutical grade of zinc oxide and good technical grades of sodium cyanide and caustic soda. In making a new zinc plating solution, preferably the ammonium thiocyanate formaldehyde resin, zinc salt (zinc cyanide or zinc oxide), caustic soda and sodium cyanide are mechanically mixed and this mechanical mixture is then dissolved in water to form the plating solution. The mechanical mixture can be, and preferably is, dissolved in water previously run into the plating tank. In preparing a new plating solution this mechanical mixing of the resin, zinc salts, sodium cyanide and caustic soda, prior to dissolving the same in water, is considerably more efiicient and time saving than separately adding to, and dissolving in, the water each of the above-mentioned constituents of the new plating bath. Of course, as the resin, zinc salts, sodium cyanide and caustic soda are depleted by operation of the bath, each is separately added to the plating solution from time to time as required. The anodes employed were at least 99.97% pure zinc. Less pure grades may be employed if the solution is purified subsequent to make up and if the anodes are alloyed with mercury and such low current densities are applied that the mercury only amalgamates with the impurities and drops to the bottom of the tank and does not go into solution.
In the above bath we find that the optimum concentration of the standard resin is between .5 and 1.0 g/l. Bright plates are obtained at 10 amp/sq. ft. and very brilliant plates at higher current densities. At lower concentrations of brightener the plates tend to be streaky at low current densities; and at higher current densities the plates are not very bright, although there is a great deal of grain refinement. At higher conccntrations only the low current density plates are bright while the plates obtained at higher current densities are ribbed or burned on the edges.
In general the solubility of ammonium thiocyanate formaldehyde resin in the plating bath is not critical. However, the brightening effect of the resin decreases with increasing solubility and vice versa the brightening effect of the resin increases with decreasing solubility of the resin. In other words, the greater the solubility of the resin the less brightening effect and the lesser the solubility of the resin the greater the brightening effect.
The use ofv larger amounts of solubilizer in preparing the resin makes it necessary to use higher concentration of resin in the bath. Slightly different optimum concentrations are found when different catalysts or solubilizers are employed,
but generally the optimum concentrations vary between .1 and 2.5 g/l.
As stated before, the low current density plates are generally not as bright as the high current density plates, consequently the brightness of a deeply recessed part varies from the high current density points to the low current density points. If the concentration of brightener is too low, the lustre may not always be as high as desired and the plate may have a slightly brownish cast. 1 These difficulties are overcome by the use of bright dips, as mentioned above, whereby the lustre is equalized or increased. I
When the optimum amount of resin has been added to the zinc bath, its tolerance to copper is increased about six times; to cadmium more than three times; to lead, at least times.
In general, the required concentration of brightener increases with increasing metal and caustic soda content in the bath and decreases with decreasing sodium cyanide content.
The substitution of other aldehydes, such as acetaldol and furfural, for formaldehyde produced resins which did not give any brightening effect. It is evident that the high lustreobtained with formaldehyde is specific.
I claim:
1. The method of electrodepositing zinc, comprising electrodepositing the said metal from a cyanide plating solution containing an ammonium thiocyanate formaldehyde resin which is soluble in the cyanide plating solution.
2. The method of electrodepositing zinc, comprising electrodepositing the said metal from a cyanide plating solution containing a solubilized ammonium thiocyanate formaldehyde resin.
3. The method of electrodepositing zinc, comprising electrodepositing said metal from a cyanide plating solution containing an ammonium thiocyanate formaldehyde resin formed by reacting ammonium thiocyanate and formaldehyde in the presence of a catalyst in the form of an alkaline salt.
4. The method of electrodepositing zinc, comprising electrodepositing said metal from a cyanide plating solution containing an ammonium thiocyanate formaldehyde resin formed by reacting ammonium thiocyanate and formaldehyde in the presence of a catalyst in the form of an acid.
5. The method of electrodepositing zinc, comprising electrodepositing the said metal from a plating bath consisting of a relatively pure cyanide solution and containing an ammonium thiocyanate formaldehyde resin which is soluble in the cyanide plating solution.
6. The method of electrodepositing zinc, comprising electrodepositing the said metal from a plating bath consisting of a relatively pure cyanide solution and containing an ammonium thiocyanate formaldehyde resin which is soluble in the plating bath and in the presence of a pure zinc anode.
7. A plating bath for electrodepositing zinc, comprising a cyanide solution of said metal and an ammonium thiocyanate formaldehyde resin soluble in the said cyanide solution.
8. A composition of matter comprising a me- 1 chanical mixture of zinc oxide, sodium cyanide,
caustic soda, and ammonium thiocyanate formaldehyde resin.
9. A compositionof matter comprising a mechanical mixture of zinc cyanide, caustic soda, sodium cyanide and ammonium thiocyanate formaldehyde resin.
10. A composition of matter comprising a mechanical mixture of a zinc salt, caustic soda, sodium cyanide and ammonium thiocyanate formaldehyde resin.
.JOHN A. HENRICKS.
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Application Number | Priority Date | Filing Date | Title |
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US77527A US2101580A (en) | 1936-05-02 | 1936-05-02 | Process for obtaining bright zinc coating |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US77527A US2101580A (en) | 1936-05-02 | 1936-05-02 | Process for obtaining bright zinc coating |
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US2101580A true US2101580A (en) | 1937-12-07 |
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US77527A Expired - Lifetime US2101580A (en) | 1936-05-02 | 1936-05-02 | Process for obtaining bright zinc coating |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2451426A (en) * | 1943-11-25 | 1948-10-12 | Du Pont | Bright zinc plating |
US2495629A (en) * | 1944-06-02 | 1950-01-24 | Poor & Co | Zinc electroplating |
US2621152A (en) * | 1950-03-30 | 1952-12-09 | Allied Res Products Inc | Zinc cyanide plating bath |
DE885035C (en) * | 1937-12-29 | 1953-07-30 | Du Pont | Process for the electrolytic production of shiny zinc coatings |
US2989449A (en) * | 1960-04-06 | 1961-06-20 | Du Pont | Electrodeposition of zinc |
US3088887A (en) * | 1958-11-03 | 1963-05-07 | Diamond Alkali Co | Electropolishing of zinc-copper alloys |
-
1936
- 1936-05-02 US US77527A patent/US2101580A/en not_active Expired - Lifetime
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE885035C (en) * | 1937-12-29 | 1953-07-30 | Du Pont | Process for the electrolytic production of shiny zinc coatings |
US2451426A (en) * | 1943-11-25 | 1948-10-12 | Du Pont | Bright zinc plating |
US2495629A (en) * | 1944-06-02 | 1950-01-24 | Poor & Co | Zinc electroplating |
US2621152A (en) * | 1950-03-30 | 1952-12-09 | Allied Res Products Inc | Zinc cyanide plating bath |
US3088887A (en) * | 1958-11-03 | 1963-05-07 | Diamond Alkali Co | Electropolishing of zinc-copper alloys |
US2989449A (en) * | 1960-04-06 | 1961-06-20 | Du Pont | Electrodeposition of zinc |
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