US2208294A - Stripping process - Google Patents
Stripping process Download PDFInfo
- Publication number
- US2208294A US2208294A US305731A US30573139A US2208294A US 2208294 A US2208294 A US 2208294A US 305731 A US305731 A US 305731A US 30573139 A US30573139 A US 30573139A US 2208294 A US2208294 A US 2208294A
- Authority
- US
- United States
- Prior art keywords
- aluminum
- coating
- attack
- sulphuric acid
- stripping process
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- 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
- C09D9/00—Chemical paint or ink removers
Definitions
- This invention relates to a stripping process and is an improvement upon the process set forth in Patent No. 2,127,469, issued August 16, 1938, upon my application Serial No. 150,213,
- the invention relates primarily to stripping of aluminum or predominantly aluminum alloys which havve been coated with varnishes, lacquers or enamels, especially oil-free, of the phenol-formaldehyde type, particularly when the coatings have been baked.
- the invention is also applicable to stripping other coated metals, but with less reactive metals than aluminum there are other processes which may also be employed.
- Aluminum or aluminum alloy materials coated with such phenol-formaldehyde materials are used to a large extent in certain industries, particularly on buckets and spinning spools in the rayon industry. Such articles after service sufgo fer damage to the coating and are rendered unfit for use.
- the underlying aluminum is still of value and it is desirable to be able to remove the coating without damaging the aluminum.
- Sulphuric acid having a specific gravity above 1.83 may be employed within the same temperature range.
- sulphuric acid having a specific gravity of 1.83 was heated to approximately 185 C. in a cast iron tank.
- the parts to be stripped are immersed in the solution either slowly enough so that the temperature thereof does not fall below 180 C., or else following preheating of the parts so that they will not cool the solution.
- the bath is carefully maintained within the range. of 180-190 C. at all times. After about minutes the resinous coating is completely removed.
- the method of removing a baked phenolformaldehyde coating from a predominantly aluminum base which comprises subjecting the coated base to a bath consisting essentially of sulphuric acid having a specific gravity of at least 1.83, while maintaining the temperature of the bath between 180 and 190 C., and continuing the treatment until the base is bright and clean.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Organic Chemistry (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Description
Patented July 16, 1940 UNITED, STATES STRIPPIN G PROCESS Charles H. Hempel, Manitowoc, Wis, assignor to Heresite & Chemical Company, a corporation of Wisconsin No Drawing. Application November 22, 1939, Serial No. 305,731
2 Claims.
This invention relates to a stripping process and is an improvement upon the process set forth in Patent No. 2,127,469, issued August 16, 1938, upon my application Serial No. 150,213,
5 filed June 24, 1937.
The invention relates primarily to stripping of aluminum or predominantly aluminum alloys which havve been coated with varnishes, lacquers or enamels, especially oil-free, of the phenol-formaldehyde type, particularly when the coatings have been baked. The invention is also applicable to stripping other coated metals, but with less reactive metals than aluminum there are other processes which may also be employed.
Aluminum or aluminum alloy materials coated with such phenol-formaldehyde materials are used to a large extent in certain industries, particularly on buckets and spinning spools in the rayon industry. Such articles after service sufgo fer damage to the coating and are rendered unfit for use. The underlying aluminum, however, is still of value and it is desirable to be able to remove the coating without damaging the aluminum.
In the process described in Patent 2,127,469, a combination of sulphuric and nitric acids was employed to remove the resinous coating without damaging the underlying active metal. The presence of nitric acid is, however, quite danger- 30 ous. The temperature of the bath containing the nitric acid is diflicult to control and it occasionally boils over with resulting considerable danger. Also, heavy fumes are likely to result from the operation.
35 Sulphuric acid by itself, however, will either fail to attack the resinous coating or, if used under conditions suitable for attacking the coating, will also attack the aluminum. It has now been discovered that if sulphuric acid having a specific gravity of not less than approximately 1.83 (66 B.) is heated to a temperature of not less than 180 C. and not more than 190 C., it will attack the resinous coating readily and will not attack the aluminum.
At temperatures below 180 C., the sulphuric acid will not attack the coating, whereas at temperatures above 190 C. it will attack the aluminum.
Sulphuric acid having a specific gravity above 1.83 may be employed within the same temperature range.
As an example of the invention, sulphuric acid having a specific gravity of 1.83 was heated to approximately 185 C. in a cast iron tank. The parts to be stripped are immersed in the solution either slowly enough so that the temperature thereof does not fall below 180 C., or else following preheating of the parts so that they will not cool the solution. The bath is carefully maintained within the range. of 180-190 C. at all times. After about minutes the resinous coating is completely removed.
What I claim as new, and desire to secure by Letters Patent, is:
1. The method of removing a baked phenolformaldehyde coating from a predominantly aluminum base which comprises subjecting the coated base to a bath consisting essentially of sulphuric acid having a specific gravity of at least 1.83, while maintaining the temperature of the bath between 180 and 190 C., and continuing the treatment until the base is bright and clean.
2. The method as set forth in claim 1, in which the coated base is maintained in the bath for approximately 20 minutes.
cmmnsmmnm
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US305731A US2208294A (en) | 1939-11-22 | 1939-11-22 | Stripping process |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US305731A US2208294A (en) | 1939-11-22 | 1939-11-22 | Stripping process |
Publications (1)
Publication Number | Publication Date |
---|---|
US2208294A true US2208294A (en) | 1940-07-16 |
Family
ID=23182092
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US305731A Expired - Lifetime US2208294A (en) | 1939-11-22 | 1939-11-22 | Stripping process |
Country Status (1)
Country | Link |
---|---|
US (1) | US2208294A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2709666A (en) * | 1950-09-04 | 1955-05-31 | Hartford Nat Bank & Trust Co | Method of locally removing the insulation layer of enamelled wire |
US3147148A (en) * | 1962-08-28 | 1964-09-01 | Western Electric Co | Method of removing a silver and phenolformaldehyde resin paint from an article |
-
1939
- 1939-11-22 US US305731A patent/US2208294A/en not_active Expired - Lifetime
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2709666A (en) * | 1950-09-04 | 1955-05-31 | Hartford Nat Bank & Trust Co | Method of locally removing the insulation layer of enamelled wire |
US3147148A (en) * | 1962-08-28 | 1964-09-01 | Western Electric Co | Method of removing a silver and phenolformaldehyde resin paint from an article |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2224695A (en) | Inhibitor | |
US2032174A (en) | Process for cleaning metal surfaces | |
US2458661A (en) | Process of cleaning metal surfaces and compositions therefor | |
US2208294A (en) | Stripping process | |
DE2717435C3 (en) | Process for removing a coating containing aluminum and chromium together with cobalt from a substrate made of a nickel-based alloy | |
US2434021A (en) | Process of bright dipping | |
US2694001A (en) | Polishing stainless steel | |
US2127469A (en) | Stripping process | |
US2152406A (en) | Methods of pickling metals | |
US2145827A (en) | Materials for and methods of treating metallic articles | |
US1965340A (en) | Apparatus for handling molten | |
US2209291A (en) | Rust removing composition | |
US4244792A (en) | Method for stripping anodized aluminum and aluminum alloys | |
US3230750A (en) | Forming and heat treatment of sheetmetal articles with organophilic cation-modified clay | |
US2709666A (en) | Method of locally removing the insulation layer of enamelled wire | |
US2837484A (en) | Method for removing carbonaceous deposits from aluminum molds | |
US2584031A (en) | Deenameling process | |
US2338045A (en) | Preparing metal for drawing operations | |
US2473456A (en) | Passivation of ferrous metals | |
JP2016132780A (en) | Acid cleaning method of steel wire material for bearing | |
US1923828A (en) | Method of deenameling | |
US2207808A (en) | Method of treating jointed electroplated articles | |
US3261710A (en) | Method for removing coating of epoxyphenolic resin and polytetrafluoroethylene from metal cases | |
US2213952A (en) | Process for treating metal surfaces | |
US2916397A (en) | Aluminum coating process |