Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/18—After-treatment, e.g. pore-sealing
  • C25D11/24—Chemical after-treatment
  • C25D11/246—Chemical after-treatment for sealing layers

Definitions

• compositions for sealing anodized aluminum surfaces contains 35-60% nickel acetate or cobalt acetate; 35-60% of the ammonium salt of naphthalene sulfonic acid, and minor quantities of a condensation product of octyl phenol with ethylene oxide and malic acid.
• the composition is applied in hot aqueous solution to the aluminum surfaces to be sealed.
• This invention relates to a method and composition for sealing anodized surfaces of aluminum and aluminumbase alloys. More particularly, it relates to a method and composition for sealing such surfaces to obtain a harder, more abrasive-resistant surface of greater resistivity while eliminating or minimizing smut formation.
• a sealing bath in common use comprises a solution of a hydrolyzable metallic salt, typically nickel acetate or cobalt acetate. Sealing with such a bath sets the dye, minimizes color bleeding and improves the permanence of the color.
• Nickel or cobalt acetate treatment however, has the disadvantage that it produces a cloudy or filmy coating on the surface of the sealed material.
• This coating referred to in the trade as smut, is particularly serious with dark shades and necessitates an additional step in the processing procedure to remove the filmy layer by mechanically butting or polishing the aluminum surface.
• the necessity for smut removal represents an added cost in the processing of aluminum articles, since each piece must be handled individually.
• the sealing bath of the invention can be prepared with ordinary tap water and has a much improved service life compared with baths heretofore used.
• the method of the invention is a variant of the hydrolyzable metal salt sealing technique, in that it employs as a sealing bath a solution of nickel acetate or cobalt acetate.
• the superior performance of the sealing bath of the invention is due to a novel combination of additives, namely, the ammonium salt of naphthalene sulfonic acid, two specific wetting agents, and malic acid.
• the sealing bath of the invention is prepared by dissolving in water a solid mixture having the following composition:
• Nickel acetate, cobalt acetate, or mixtures thereof 35-60 4250 Ammonium salt of naphthalene sulionlc acid (d 1spersant)' 35-60 42-50 Sodium lauryl sulfate (wetting agent) 0. 03-0. 3 0. 05-0. 15 Octyl phenoxy polyethoxy ethanol (wetting agent) 0. 1-1. 0 0. 2-0. 5 Make acid (bufier) 0. 5-4. 0 1. 0-2. 0
• octyl phenoxy polyethoxy ethanol referred to above, and which is contemplated for use in the invention, is the product produced by the condensation of one mole of isoor n-octyl phenol with about 12-13 moles of ethylene oxide.
• a particularly preferred embodiment of the sealing composition of the invention contains, on a water-free basis, about 49% of nickel acetate, cobalt acetate or mixtures thereof; about 49% of the ammonium salt naphthalene sulfonic acid; about 0.1% of sodium lauryl sulfate; about 0.25% of octyl phenoxy polyethoxy ethanol; and about 1.5% of malic acid.
• the sealing composition of the invention is used by dissolving it in water at a concentration of about 2-16 grams per liter, preferably about 2.5-10 grams per liter, and optimally about 5-8 grams per liter.
• The. sealing solution is heated to a temperature of about F. to the boiling point of the solution and preferably about 185- 205 F.
• the pH of the solution is adjusted as necessary with a suitable acid or base, such as acetic acid, ammonium hydroxide or sodium hydroxide, to achieve a value within the range of about 5.2-5.8 and preferably about 5.4-5.6.
• Contact of the sealing solution with the surfaces to be treated is maintained in the conventional manner for about 3-20 minutes and preferably about 5-10 minutes.
• the manipulative aspects of the sealing operation are not critical and any of the methods which have been used in the past may be employed with the novel baths of the invention.
• a sealing bath is prepared by dissolving in city (tap) water about 4.4 grams per liter of a composition consisting of 49 parts by weight of nickel acetate, 49 parts by weight of the ammonium salt of naphthalene sulfonic acid, 0.25 part by weight of the condensation product of one mole of isooctyl phenol with about 12-13 moles of ethylene oxide, 0.08 part by weight of sodium lauryl sulfate, and 1.5 parts by weight of malic acid.
• the pH of the resulting solution is adjusted with acetic acid to a value of 5.4.
• This solution maintained at a temperature of about 192 F., is used to seal an Anoclad 11 sheet having a 215 R1 anodic finish for about 10 minutes.
• the sealed sheet is essentially smut free.
• the sheets sealed in accordance with the invention show greater resistance to acid dissolution and equivalent surface resistivity.
• EXAMPLE II A sealing bath is prepared using the same ingredients and concentrations as those of Example I, except that deionized water is used in place of city water. The use of deionized water results in sealed samples having slightly lower acid dissolution rate and slightly higher resistance values than samples sealed with the solution of Example I. The aluminum surfaces sealed with the solution are again essentially smut free.
• a water-soluble composition for sealing anodized aluminum comprising about 35-60% by weight of nickel acetate, cobalt acetate or mixtures thereof; about 35-60% by weight of the ammonium; salt 16f naphthalene sulfonic acid; about 0.03-0.'3% byweight ofsodium laury-l-sulfate; about 01-10% by weight'of the condensation'productof one mole of octyl phenol with about 12-13 moles of ethylene oxide; and about 0.5-4.0% by weight of malic acid.
• a composition in accordance with claim 1 which contains about 42-50% by weight of nickel acetate, cobalt acetate, or mixtures thereof; about 4250% by weight of the ammonium salt of naphthalene sulfonic acid; about 0.05-0.15% by weight of sodium lauryl sulfate; about 02-05% by weight of the condensation product of one mole of octyl phenol with about 12-13 moles of ethylene oxide; and about 1.0-2.0% by weight of malic acid.
• a composition in accordance with claim 1 which contains about 49% by weight of nickel acetate, cobalt acetate, or mixtures thereof; about 49% of the ammonium salt of naphthalene sulfonic acid; about 0.1% by weight of sodium lauryl sulfate; about 0.25% by weight of the condensation product of one mole of octyl phenol with about 12-13 moles of ethylene oxide; and about 1.5% by weight of malic acid.
• A. bath for sealing anodized aluminum comprising an aqueous solution containing about 2-16 grams per liter of a composition of claim 1.
• a bath in accordance with claim 4 containing about 5-8 grams per liter of a composition of claim 1.

Landscapes

• Chemical & Material Sciences (AREA)
• General 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)
• Sealing Material Composition (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Electroplating And Plating Baths Therefor (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=21761993

Family Applications (1)

Country Status (12)

Cited By (7)

Families Citing this family (2)

• 1970
  • 1970-02-24 US US13832A patent/US3647649A/en not_active Expired - Lifetime
• 1971
  • 1971-02-23 LU LU62641D patent/LU62641A1/xx unknown
  • 1971-02-23 SE SE7102322A patent/SE382471B/xx unknown
  • 1971-02-23 NL NL7102406A patent/NL7102406A/xx unknown
  • 1971-02-24 DE DE19712108725 patent/DE2108725A1/de active Pending
  • 1971-02-24 CA CA106,190,A patent/CA950604A/en not_active Expired
  • 1971-02-24 CH CH268471A patent/CH570467A5/xx not_active IP Right Cessation
  • 1971-02-24 ES ES388577A patent/ES388577A1/es not_active Expired
  • 1971-02-24 FR FR7106212A patent/FR2078992A5/fr not_active Expired
  • 1971-02-24 BE BE763413A patent/BE763413A/xx unknown
  • 1971-04-19 GB GB2242471A patent/GB1310644A/en not_active Expired
  • 1971-10-13 OA OA54394A patent/OA03814A/xx unknown

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