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
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/44—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications
  • C09D5/4407—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes for electrophoretic applications with polymers obtained by polymerisation reactions involving only carbon-to-carbon unsaturated bonds
  • C09D5/4411—Homopolymers or copolymers of acrylates or methacrylates
• • 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 methyl or hydrogen
• R is alkyl of one to four carbon atoms
• n is a positive whole integer of l to 3, inclusive
• R" is alkyl of one to four carbon atoms
• CH CH CH ,CI-I2C CH, --CH COOCH CI-I COOC DV5, -CI-I COR
• R is as 20 Claims, No Drawings- ACID ZINC ELECTROPLATING BACKGROUND OF THE INVENTION 1 Field of the Invention
• This invention relates to acid zinc electroplating baths and processes.
• an aqueous acid zinc electroplating bath comprising an aqueous solution of a zinc salt maintained at a pH in the range of about 2.5 to 5.5 and having dissolved therein in an amount to give a bright zinc deposit an acrylate selected from the group consisting of (1) an acrylate monomer of the general formula:
• R is methyl or hydrogen, R is alkyl of one to four carbon atoms, n is a positive whole integer of l to 3, inclusive,
• CH2CH2CH2SO3 and X is CH SO C I-I SO halide or is absent when (2) a homopolymer of said acrylate monomer and (3) a copolymer of said acrylate monomer with at least one ethylenically unsaturated monomer selected from the group consisting of an a, ,B-ethylenically unsaturated monocarboxylic acid, an alkyl ester of said acid wherein the alkyl group is from one to four carbon atoms, acrylonitrile, acrylamide, methacrylamide, vinyl acetate, vinyl sulfone and vinyl pyridine, the molar ratio of said acrylate monomer to said vinyl monomer being within the range of 0.9:0. 1 to 0. 1:09.
• the invention pertains to the elec trodeposition of zinc from acid zinc plating baths known to those skilled in the art. These baths can be formed by the dissolution of zinc oxide in non-complexing acids such as sulfuric or sulfarnic.
• the pH of the baths is adjusted to an operating range between about 2.5 and 5.5, preferably between 3.5 and 4.5, by the addition of aqueous ammonia and ammonium salts.
• the baths can be formed by thedissolution of commercial zinc and ammonium salts, such as the sulfates, in water with subsequent adjustment of the pH to a desired level in the normal operating range by means of aqueous ammonia, other alkali metal base or acid as required.
• commercial zinc and ammonium salts such as the sulfates
• aqueous ammonia other alkali metal base or acid as required.
• baths based on zinc sulfate are used. While high chloride baths are to be avoided-generally any such commercial bath will have a pH greater than 5.5a small amount of chloride ions (up to 2 g./l.) in sulfate baths can be tolerated and in some cases may be beneficial.
• Temperature of operation is normally between 15C. and 45C. and is usually between 20C. and 30C.
• zinc salts e.g., zinc sulfate and zinc sulfamate
• zinc salts e.g., zinc sulfate and zinc sulfamate
• other metal salts such as sodium sulfamate or potassium sulfate may be added to enhance electrical conductivity.
• the zinc electrodeposits obtained from the acid sulfate baths are typically coarse and dull gray in appearance and have little commercial value, especially in the decorative plating of screws, chain, and other items of hardware.
• certain quaternized dialkylaminoalkylacrylate monomers and more particularly homopolymers of quaternized dialkylaminoalkylacrylates or copolymers with other ethylenically unsaturated monomers are added to the acid zinc baths of the type described above in amounts from 0.05 to 5 g./l., preferably 0.1 to 1 g/l. a distinct improvement in the quality of the zinc electroplate results.
• the monomers have the least effect showing only a smoothing action.
• the homopolymers impart brightness and shine to the deposits while the copolymers have been found to produce zinc deposits of commercially acceptable quality.
• excellent throwing power is also obtained from baths using such copolymers as is demonstrated by uniform coverage between the threads and in the head recesses of ordinary wood screws during barrel plating.
• the quaternized dialkylaminoalkylacrylates useful in this invention have the general formula:
• R is alkyl of one to four carbon atoms
• n is a positive whole integer of l to 3, inclusive, 1
• Z-methacryloxyethyl, dimethyl, 3-sulfopropyl ammonium betaine which may be prepared by the addition of propane sulfone to dimethylaminoethylmethacrylate.
• This monomer may be readily polymerized in aqueous solution under the action of a peroxide initiator and mild temperature (6080C.) to give a homopolymer which shows similar plating characteristics to the monomer but which has the additional benefit that only one-third to one-tenth the amount of polymer is required to produce equivalent electroplate to that obtained from the monomer.
• a still further improvement in plating performance is obtained by the use of copolymers of quaternized dialkylaminoalkylacrylates with other ethylenically unsaturated monomers such as an a, B-ethylenically unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid, an alkyl ester of said acid wherein the alkyl group is from one to four carbon atoms, methacrylamide, acrylamide, acrylonitrile, vinyl acetate, vinyl sulfone and vinyl pyridine.
• Such copolymers usually have an additional advantage in that the ductility of the deposit is frequently markedly improved, i.e., brittleness is avoided.
• Z-methacryloxyethyl allyl, dimethyl ammonium bromide Z-methacryloxyethyl, propargyl, dimethyl ammonium bromide Z-methacryloxyethyl, cyanomethyl, dimethyl ammonium chloride 2-methacryloxyethyl, carboxamidomethyl, dimethyl ammonium chloride Z-methacryloxyethyl, carbomethoxy dimethyl ammonium chloride -2-methacryloxyethyl, 2-carboxyethyl, dimethyl ammonium betaine 2-acryloxyethyl, diethyl, methyl ammonium methyl sulfate methyl,
• EXAMPLE 3 Three g. (0.01 mol) 2-methacryloxyethyl, dimethyl, 3-sulfopropyl ammonium betaine, 0.75 g. (0.01 mol) methacrylic acid, 30 g. water and 0.04 g. potassium persulfate were heated at C. for 1 hour to give a slightly viscous product. Added at the rate of 20 ml./l. of acid zinc plating bath, this product performed as an excellent low current density brightener in the barrel plating of screws.
• EXAMPLE 4 Z-Methacryloxyethyl, dimethyl carbomethoxymethyl ammonium chloride (B) was prepared as white crystals by adding 13 g. methyl chloroacetate to 8 g. dimethylaminoethylmethacrylate in acetone and standing at room temperature for 24 hours.
• the white crystals contained: C--49.70%, I-17.60%, N--5.27%. Theory: C49.82%, H7.55%, N5.28%.
• Poly B was prepared by heating at 80C. for 1 hour, 5 g. B, g. water, 0.05 g. potassium persulfate. The clear viscous solution was poured into acetone to precipitate poly B as a white rubbery polymer. After drying under vacuum at 60C. it became brittle and was easily soluble in water.
• EXAMPLE 5 2-Methacryloxyethyl; dimethyl cyanomethyl ammonium chloride (C) was prepared as white crystals by adding 8 g. of chloroacetonitrile to 8 g. of dimethylaminoethylmethacrylate in 16 g. of methyl ethyl ketone. The product crystallized out on standing overnight. It contained: 51.55% C, 7.34% H, 12.12%N. Theory: 51.75% C, 7.34% H, 12.07% N.
• Poly C was prepared in a similar manner to the poly B of Example 4. In the barrel plating of screws it was found to also behave similarly.
• Poly D was prepared by polymerizing D in aqueous solution under the action of potassium persulfate as an initiator following the practice of Example 4. Poly D was found to be an effective additive for the barrel plating of screws.
• EXAMPLE 7 Z-Methacryloxyethyl, dimethyl propargyl ammonium bromide (E) was prepared by adding 8 g. of propargyl bromide to 12 g. of dimethylaminoethylmethacrylate in 20 g. of methyl ethyl ketone. The white crystals formed analyzed as C-47.88%, l-l6.58%, N5.l3%. Theory: C-47.85%, 1-l6.52%, N5.07%. Poly E, prepared following the teachings of the foregoing examples was found to be an effective brightener for acid zinc electroplating.
• EXAMPLES s-13 A series of copolymers of 2-methacryloxyethyl trimethyl ammonium methyl sulfate (X) with methacrylic acid (Y) in mol. ratios of X/Y varying between 0.9/0.1 and 0.1 to 0.9 were prepared by polymerizing the monomers in aqueous solution at C., using potassium persulfate as catalyst. The copolymers were precipitated in acetone and dried under vacuum at 60C. to give brittle colorless solids easily soluble in water. Composition was found by microanalysis as shown in Table 1.
• An aqueous acidzinc electroplating bath comprising an aqueous solution of a zinc salt maintained at a pH in the range of about 2.5 to 5.5 and having dissolved 7 8 therein in an amount to give a bright zinc deposit an 5.
• the acid electroplating bath of claim 2 wherein acrylate selected from the group consisting of (1) an the ethylenically unsaturated monomer is methacrylic acrylate monomer of the general formula: acid.
• R is methyl or hydrogen
• R 18 methyl or hydrogen
• the acid electroplating bath of claim 9 wherein the general formula: the pH of the bath is within the range of about 3.5 to
• the copolymer having a aqueous acid zinc electroplating bath having a zinc salt molar ratio of said acrylate monomer to said undissolved therein the improvement comprising mainsaturated monomer being within the range of taining said bath at a pH in the range of about 2.5 to 5.5 0.7/0.3 to 0.3/0.7. and adding thereto in an amount efiective to give a 3.
• R is methyl or hydrogen
• R is alkyl of one to four carbon atoms
• n is a positive whole integer of l to 3 inclusive
• R is methyl or ethyl
• R" is alkyl of one to four carbon atoms, -CH CH CH CH CH, CH,COOCH CH COOC CH COR where R is as defined above, CH CONH -CH CN, CH CH 0H, --CH CH COO' or CH CH CH SO and X is CH SO H SO halide or is absent when R" is -CH CH COO- or -CH CH CH SO with at least one ethylenically unsaturated monomer selected from the group consisting of an a, B- ethylenically unsaturated monocarboxylic acid, an alkyl ester of said acid wherein the alkyl group is from one to four carbon atoms, acrylonitrile, acrylamide, methacrylamide, vinyl acetate, vinyl sulfone and vinyl pyridine, the copolymer having a molar ratio of said acrylate monomer to said unsaturated monomer within the range of 0.7/0.3 to 0.3/0.7 and the bath is at a temperature in the range of
• R is methyl or hydrogen
• R is methyl or ethyl
• the process of claim 15 wherein the acrylate is a homopolymer of an acrylate monomer of the general formula:

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Electrochemistry (AREA)
• Metallurgy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Molecular Biology (AREA)
• Wood Science & Technology (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Electroplating And Plating Baths Therefor (AREA)

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Citations (2)

• 0
  • BE BE795359D patent/BE795359A/fr unknown
• 1972
  • 1972-02-15 US US00226542A patent/US3723262A/en not_active Expired - Lifetime
  • 1972-02-15 US US00226543A patent/US3723260A/en not_active Expired - Lifetime
• 1973
  • 1973-02-08 NL NL7301796A patent/NL7301796A/xx unknown
  • 1973-02-14 IT IT20399/73A patent/IT979117B/it active
  • 1973-02-14 FR FR7305187A patent/FR2172222B1/fr not_active Expired
  • 1973-02-15 DE DE19732307520 patent/DE2307520A1/de active Pending
  • 1973-02-15 JP JP48017960A patent/JPS4892235A/ja active Pending

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