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
  • C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt
  • C25D3/14—Electroplating: Baths therefor from solutions of nickel or cobalt from baths containing acetylenic or heterocyclic compounds
  • C25D3/16—Acetylenic compounds

Definitions

• This invention relates to electroplating and, more particularly, to electrodepositing nickel from an aqueous acidic nickel plating bath.
• the invention is based on the discovery that the bisulfite addition products of acetylenic compounds, when incorporated in a nickel electroplating bath, are remarkably effective for promoting the formation of very bright and ductile electrodeposits of nickel over a wide current density range and, more over, that certain of these bisulfite adducts are also capable of exerting a pronounced leveling eflect on the electroplate formed during the plating operation.
• the initial bisulfite addition product of an acetylenic compound appears to be a conjugated 0a, ⁇ 3-UI1S3tl1l'8tfid sulfonic acid (or sulfonate) which is capable of undergoing further addition, in the presence of excess bisulfite, to form the second adduct.
• the apparent structure of this second bisulfite addition product is that of a saturated disulfonic acid (or disulfonate), in which the sulfonic acid (or sulfonate) groups are vicinal.
• the bisulfite addition products prepared by reacting a,a-disubstituted acetylenic compounds with N times an equimolar quantity of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, are unusually efiective for promoting the formation of bright and even brilliant electrodepo'sits of nickel over very wide current density ranges when a minute quantity of the bisulfite adduct is incorporated in an aqueous acidic nickel plating bath.
• these bisulfite addition products In addition to their brightening capacity, have also been found to exert a pronounced leveling effect during the formation of the electrodeposit.
• the bisulfite addition products of any u,u-disubstituted acetylenic compound having a functional group on each of the carbon atoms adjacent to the acetylenic bond (or to one of the acetylenic bonds it the compound is a polyene) may be selected for inclusion in nickel plating baths.
• the particular a,a-disubstituted acetylenic compound used to prepare the bisulfite adduct contain at least one m,ot'-diSllbStit11t6d acetylenic bond which is neither sterically nor electronically hindered from undergoing reaction with a chain-carrying sulfite radical, and that the bisulfite adduct be capable of being dissolved in acid without undergoing decomposition.
• the invention provides an improved process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic nickel plating solution of at least one nickel salt in which there is dissolved from about 0.1.to about 100 millirnoles per liter of the bisulfite addition product of an oz,oc'-disubstituted acetylenic compound and N times an equivalent weight of a compound capable of forming a chaincarrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compounds.
• the common structural feature of the oc,oc'-disubstituted acetylenic compounds used in preparing these bisulfite addition products is the presence of a functional group (R, and R on each of the carbon atoms vicinal (or alpha) to an acetylenic bond, as represented by the following structural configuration:
• R, and R or substituents is selected from the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure O[OHg( DH-O],,H in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxy methyl, ethenyl, and glycidyl, and n is an integer from 1 to 20.
• the bisulfite addition products are conveniently prepared by refluxing an aqueous solution containing both the acetylenic compound and an alkali metal bisulfite (or sulfite) until most of the bisulfite (or sulfite) ions have been consumed.
• the rate at which bisulfite ion is consumed in the reaction mixture is accelerated by passing gaseous oxygen through the mixture or by adding a trace amount of a free radical initiator (i.e., benzoyl peroxide) to the reactants; the rate is sharply diminished, on the other hand, by adding trace amounts of free radical inhibitors, such as hydroquinone and similar antioxidants, to the reaction mixture.
• compound capable of forming a chain-carrying sulfite radical denotes the alkali metal or metal bisulfites, sulfites, and metabisulfites, as well as sulfurous acid or gaseous sulfur dioxide. All of these compounds may be used to form bisulfite adducts of :,0t-diSl1bStiil1t6d acetylenic compounds which, in turn, may be used in nickel plating baths in accordance with this invention.
• the reaction mixture may be added directly (or decolorized and then added directly) to the nickel plating bath or, alternatively, the bisulfite addition product 'may be pre- 'cipitated or crystallized from the reaction mixture and then added to the plating bath, the same plating results being obtained in either case.
• the bisulfite addition products may be used in concentrations as high as 100 millimoles per liter, or even more, there is no particular advantage to be gained from the higher concentrations, and they are preferably used in the range of concentrations from about 0.1 to about 20, or even in the relatively narrow range from 1 to 20 millimoles per liter.
• Bisulfite addition to a symmetrically substituted Z-butyne generally yields the corresponding 1,4-disubstituted-2-butene-2-sulfonic acid (or sulfonate), whereas bisulfite addition to an unsymmetrically substituted Z-butyne generally yields a mixture of isomeric Z-butene-Q-sulfonic acids or their salts.
• Table I lists a number of examples of various 1,4-disubstituted-2-butynes, both symmetrical and unsymmetrical, which have been used to prepare bisulfite addition products which, in turn, have been successfully employed in embodiments of this invention.
• R -R unsymmetrical butyne
• the reaction mixture containing both, prepared'by reacting an unsymmetrically substituted Z-butyne with an alkali metal bisulfite may be incorporated in nickel plating solutions without first fractionating each isomer. If the individual isomers are desired, however, then they may be separated 'by chromatographic adsorption techniques.
• Nickel sulfate NiSO -7H O 300 Nickel chloride, NiCl -6H O 45 Boric acid, H BO 41.25
• an electrodeposit of nickel was formed on either a stainless steel panel or on a steel panel having roughness value (root mean square value in microinches) of 20, or on both panels, using a bath temperature of 60 C., vigorous air agitation, and an average current density of 60 amperes per square foot (unless otherwise stated).
• the average thickness of each electrodeposit was 0.025 mm. (0.001 inch).
• the bisulfite addition product could be used in nickel plating baths without further purification, or it could be precipitated or crystallized from solution and then redissolved in the plating bath, the plating results being the same in either case.
• the resulting bisulfite addition when incorporated in i a nickel plating 'bath in concentrations of from 1.1 to 4.4 millimoles per liter, gave a high degree of leveling and a very Wide bright plating range of current densities. Moreover, the electroplates formed from baths containing the bisulfite adduct have notably great ductility and a remarkably low internal stress.
• a brilliant nickel electrodeposit was formed over a very wide range of current densities on a polished steel panel from a Watts nickel plating bath containing 300 grams per liter of nickel sulfate, 45 grams per liter of nickel chloride, 41.25 grams per liter of boric acid, and 8.8 millimoles per liter of the bisulfite addition product of equimolar quantities of 4-methoxy-2- butyn-l-ol and potassium bisulfite, the preparation of which is described above.
• EXAMPLE III Excellent results are also obtained when the electroplate is formed from a plating bath containing the bisulfite addition products of a 1,4-dihalo-2-butyne.
• a brilliant nickel electrodeposit was formed on a polished steel panel in an open vessel, using a plating bath and plating conditions similar to those described in Example I, with the sole exception that concentrations varying from 2.2 to 6.6 millimoles per liter of the bisulfite addition product of equimolar proportions of 1,4-dichloro-2-butyne and sodiumbisulfite were used in the plating bath in place of the bisulfite adduct of 2-butyne-l,4-diol.
• An electrodeposit of nickel was formed in an open vessel on panels of steel and polished stainless steel, using a basic Watts bath having substantially the same composition (in nickel sulfate, nickel chloride, and boric acid) described previously.
• the deposit formed at a bath temperature of C. and at a pH of 3.1 to 3.5 was matte and slightly stressed.
• a bright to brilliant electrodeposit was formed under the same plating conditions. Both the adhesion of the deposit to the stainless steel and the ductility of the foil were excellent.
• Increasing the bath concentration of the bisulfite adduct to 4.4 millimoles per liter resulted in a slight increase in brilliance of the electroplate and a marked increase in the leveling eflect.
• the bisulfite addition product of 1,4-di-(p-hydroxychloropropoxy)-2-butyne which is the reaction product of 2-butyne-1,4-diol and epichlorohydrin, was prepared by adding an equimolar proportion of 1,4-di-(fi-hydroxychloropropoxy) -2-butyne to an aqueous solution of sodium bisulfite and refluxing the mixture for several hours. After cooling, the solution was diluted, decolorized with activated carbon, and filtered. Methanol was added to the filtrate, with vigorous stirring, to precipitate the bisulfite 7 addition product. After filtration, the precipitate was dried in vacuo and used without further purification.
• a brilliant and ductile electrodeposit of nickel was formed on a polished steel panel, using a plating bath and plating conditions similar to those described in Example I with the sole exception that 2.2 millimoles per liter of the bisulfite addition product of 1,4-di-(fl-hydroxy- 'y-chloropropoxy)-2-butyne, the preparation of which is described above, were used in the bath in place of the bisulfite adduct of 2-butyne-l,4-diol.
• EXAMPLE VI Equimolar proportions of 1,4-diacetoxy-2-butyne and sodium bisulfite were dissolved in water and the resultant solution refluxed for about 5 hours. The reaction mixture was diluted with water, rlecolorized with activated carbon, filtered under suction, and the filtrate used in a plating bath without further purification.
• the invention therefore contemplates the use of the bisulfite addition products of a,a'-disubstituted acetylenic compounds in any aqueous acidic nickel electroplating bath.
• each of R and R are substituents of the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure O-[OH;( ]I-IO]nH in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, n is an integer from 1 to 20 and M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.
• the process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 20 rnillimoles per liter of a compound represented by the formula in which each of R and R are substituents selected from the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure R0 O-[CH ]H-O]n--H in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.
• the process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 20 millimoles per liter of a compound represented by the formula in which R is a substituent selected from the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure R0 O-[CHg( JH-O] H in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.
• R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 9 1 to 20, and M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.
• the process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 20 millimoles per liter of a compound represented by the formula in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, n is an integer from 1 to 20, and R is a substituent selected from the group consisting of hydroxy, alkoxy, alkanoxy, halogen, and polyoxy groups having the structure R0 ocH2('JH o .,-H
• M is a cation substi-tuent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.
• the process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of 2-butyne-1,4-diol and a compound capable of forming a charm-carrying sulfite radical selected from the group consisting of sulfiurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected firom the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.
• the process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of 1,4-di-(B-hydroxyethoxy)-2-butyne and a compound capable of forming a chain-carrying sulfite radical selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected firom the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.
• the process for producing bright nickel deposits which comprises electrodepositing nickel from an aque ous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of 1,4-di-(ti-hydroxy-' -chloropropoxy)-2-butyne and a compound capable of forming a chain-carrying sulfite radical selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.
• the process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of 1,4-diacetoxy-2-butyne and a compound capable of forming a chain-carrying sulfite radical selected from the group consisting of sulfur-ous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

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• 1958
  • 1958-09-26 US US763454A patent/US3002902A/en not_active Expired - Lifetime
• 1959
  • 1959-08-14 GB GB27853/59A patent/GB869403A/en not_active Expired
  • 1959-09-25 FR FR806057A patent/FR1241313A/fr not_active Expired

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