Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids

Definitions

• An automobile is washed in the usual manner in an automatic carwash and immediately after washing, while the automobile is still wet, it is sprayed with an aqueous solution of a first anti-rust agent and, after a period of time, with an aqueous solution of a second anti-rust agent.
• the solutions are sprayed on in mist form, suitably with spray pistols or in automatic carwashes with fixed nozzles which spray the anti-rust agents in mist form.
• the solutions are applied on the one hand from below in a moving ramp, and on the other hand from above and from the side via the movements of the carwash portals. Under the present conditions, a spraying time of about 15 seconds for each solution was found to be suitable.
• the first anti-rust agent consists of an aqueous solution of an anionic corrosion inhibitor, which disperses very easily and rapidly over the moist, clean metal and forms a protective film.
• an anionic corrosion inhibitor which disperses very easily and rapidly over the moist, clean metal and forms a protective film.
• a number of different anionic,corrosion inhibitors have been used and tested, but particularly good results have been obtained with polyphosphates.
• Polyphosphate is a linear polymer with the general formula in which n is 2 or more. Optimal values of n for corrosion protection lie between 3 and about 20.
• the negative hexametaphosphate ion can also form under special conditions,positive ions of the type thus having a cathodic inhibiting effect.
• the polyphosphate film formed increases the cathodic polarisation markedly.
• the second cationic rust inhibitor sprayed on thereafter is fixed with its hydrophilic portion in the polyphosphate film thus imparting water-repellant characteristics to the resulting film.
• the second spraying also covers "greasy" portions of the metal, remaining paint, spots etc.
• a number of cationic compounds were investigated and the best result was achieved with amines, especially long-chained,quaternary ammonium compounds, preferably tallow amine ethoxylate.
• the molecular structure for this compound is in which R is derived from a fatty acid and x+y+z varies between 3 and 10 or higher. The presence of two amino groups in the molecule increases the cationic properties.
• Non-ionic surfactants have also been tested, since they have certain advantages in handling, e.g. less tendency to foam, but the results have not been as favourable.
• the anti-rust agent according to the invention is water-based and has a very low surface tension, it has a very good spreading ability and penetrates easily into all places where it is at all possible for moisture to reach such as joints, cracks in the undercarriage surface, beneath layers of dirt, etc.
• composition of the-solutions can be varied within very wide limits, and below will be given only an example of two solutions and the test results with them.
• Corrosion test The test was carried out with weighed test panels, protectively painted on the reverse side, of cold- rolled steel with dimensions and surface treatment according to the following.
• test panels under (c) and (d) were provided with a cross-scratch down to the sublayer.
• test panels were exposed lying on a rack in a chamber with the bottom surface covered with water.
• a water mist was sprayed for 10 minutes per day without spraying the test surface directly, but allowing water mist to fall down freely on all test surfaces.
• the test temperature was 23 ⁇ 2°C, and the relative humidity was 85-90% except during the spray periods when it was 100%.
• the total exposure tine was 28 days.
• test panels each from groups (a), (b) and (d) , and one test panel from group (c) were moistened with tap water, were sprayed with inhibitor solution 2 and thereafter with inhibitor solution 1 in a total amount of about 35 g/m 2 .
• the test panels were then coated with a 2-3 mm thick layer of synthetic road dirt.
• the synthetic road dirt was prepared as follows: Washed quarts sand 112 g of No. 65, 26 g of No. 30 and 50 g of No. 18 as well as 12 g of kaolin powder was added to 20 ml of a 15% aqueous solution of sodium chloride and was mixed thoroughly.
• test panels After an exposure time of one.week the test panels were cleaned by high-pressure spraying with water and new inhibitor solutions were applied as well as well as new road dirt. The process was repeated at one week intervals throughout the entire exposure period. A pair of plates from each of the groups (a), (b) and (d) were treated in the same manner but at two week intervals and a pair of plates from each group were treated only once prior to the beginning of the exposure.
• Test panels from group A were first coated with road dirt, were moistened with tap water and sprayed with the inhibitor solutions. Without removing the road dirt, the test panels were then sprayed with the inhibitor solutions according to the same schedule as under A.
• test panels from groups (c) and (d) were moistened and treated with the inhibitor solutions. After exposure for one day, the test panels were rinsed off with tap water and returned to the test chamber. After six days of further exposure, one test panel, E 1 of each type, was removed and treated again according to the above. This was repeated once per week during the entire test period. The two other test panels, E 2, were exposed without further treatment.
• the protective coating was then removed from the reverse side of the test panels from groups (a) and (b), and the metal loss was calculated by derusting in Clarke's solution and subsequent weighing.
• Penetration into cracks was determined according to SS 18 60 17. Eight blasted plates were screwed together two by two somewhat staggered in relation to each other. The blasted surfaces faced each other and had point contact over the common surface. The plates were placed vertically and were sprayed perpendicular to the downwardly facing blasted side. After 7 days at 23 ⁇ 2°C the plates were separated and-the penetration was determined.
• Spraying with the inhibitor solutions and water proceeded as according to the following:
• a pair of plates was first sprayed with water; then with corrosion protector 2 and corrosion protector 1.
• a pair of plates was sprayed with corrosion protector 2 and corrosion protector 1, the treatment being repeated after 2 and 5 days.
• a pair of plates was first sprayed with water and then with corrosion protector 2 and corrosion protector 1, the treatment being repeated after 2 and 5 days.
• the rust protection on a moist surface was determined according to SS 18 60 18. 0.1 ml of corrosion protector 2 and of corrosion protector 1 was dropped on a blasted plate surface which was moistened with 3% sodium chloride solution. After storage at 23 i 2°C and 50 ⁇ 5% relative humidity for 48 hours, the test plates were examined with regard to corrosion of the surfaces coated with inhibitor solutions. The spread of the inhibitor solutions on the plate surface was measured and the mean diameter was calculated.
• the test performed has demonstrated that the inhibitor system, under the conditions prevailing in the test chamber, on an average was able to bring down the rate of corrosion of unprotected pure steel coated with synthetic road dirt by about 45%, for unprotected pure steel without coating with road dirt by about 90%, for rusty steel coated with road dirt by 40-75% and for rusty steel without coating with road dirt by about 90%.
• the inventive corrosion protector is also very effective on other metals than iron, as the results with aluminium, copper and zinc demonstrate. It is mentioned above that the spreading capacity of the inventive water-based corrosion protector makes it possible to protect all places where moisture can penetrate.
• the entire rust film also provides improved adhesion for the underseal which can be applied e.g. in the wheel housing to protect against stones.
• anti-rust agents according to the invention provide a synergetic anti-rust effect from the two inhibitors when applied in the manner described above. The effect is however totally eliminated if the anti-rust agents are mixed prior to spraying, or if the spraying is done in another order.
• This method makes it possible to rust-protect an automobile simply and inexpensively without the customer having to relinquish his automobile.
• the treatment can be easily done as a standard step in washing.

Applications Claiming Priority (2)

Publications (1)

Family

ID=20341348

Family Applications (1)

Country Status (5)

Cited By (1)

Citations (5)

• 1980
  • 1980-07-01 SE SE8004865A patent/SE8004865L/ not_active Application Discontinuation
• 1981
  • 1981-06-30 NO NO812234A patent/NO812234L/no unknown
  • 1981-06-30 EP EP81850119A patent/EP0043360A1/de not_active Withdrawn
  • 1981-06-30 FI FI812048A patent/FI812048L/fi not_active Application Discontinuation
  • 1981-06-30 DK DK291781A patent/DK291781A/da unknown

Patent Citations (5)

Also Published As

Similar Documents

Legal Events