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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
• • 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
  • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
  • C23D3/00—Chemical treatment of the metal surfaces prior to coating
• • 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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/08—Iron or steel
  • C23G1/088—Iron or steel solutions containing organic acids
• • 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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
  • C23G1/19—Iron or steel

Definitions

• the invention relates to the treatment of metal sheets preparatory to the application of vitreous enamel, particularly iron and steel sheets. More particularly, it relates to a treatment with materials which do not form noxious and poisonous gases, yielding clean and silver-white metal surfaces.
• each r of these baths is adjusted to a suitable pH value.
• This process for the pretreatment of metal surfaces preparatory to vitreous enameling and especially for the removal of salt residues therefrom after treatment with acidic solu-' tions is characterized by a treatment of the metal surfaces with solutions of alkanolamines containing at least 3 alkanol groups in the molecule and alkali.
• alkali sodiumor potassium hydroxide, soda, potassium carbonate, or mixtures thereof
• the pH of the solutions always is above 10.
• alkanolamines of the type named above are trialkanolamines having an alkyl radical of 2 to 4 carbon atoms, especially triethanolamine and polyalkanol compounds, such as N,N,N',N'-tetrakis (Z-hydroxypropyl) ethylenediamine.
• the range of activity of solutions of this kind is particularly surprising as satisfactory metal surfaces cannot be obtained with the use of solutions which contain merely alkali and complex-forming compounds, e.g., gluconates, anhydrous phosphates, oxalates or tartaric acid.
• aminopolycarboxylic acids or their salts are readily accessible acids such as nitrilotriacetic acid, ethylenediaminotriacetic acid, and ethylenediaminotetraacetic acid, and their water-soluble alkali metal salts.
• the advantage of their addition consists particularly in the independence of such compounds from the hardness of the water employed.
• solutions containing solely aminopolycarboxylic acids and alkali do not produce satisfactory results.
• the concentration of the mixture in the aqueous solutions themselves is 1 to 5 weight percent. Generally, it is of advantage to prepare concentrates and to dilute them just prior to application. It has been found opportune to hold the alkali content, calculated on the total components exclusive of water, above percent, and preferably between and weight percent. When aminopolycarboxylic acids are added, their content, also calculated on the total components exclusive of water, should amount to up to 20 weight percent. The remainder is alkanolamine, also exclusive of water. As stated above with respect to prior art, the rinsing baths following the acid pretreatment, such as etching or degreasing, frequently are adjusted to a given pH value in order to effect neutralization.
• the process according to the invention When the process according to the invention is employed, it is opportune to use an alkaline-reacting intermediary rinse bath. In certain instances it is advantageous toadd even to such an intermediary rinse bath alkanolamine and, if desired, aminopolycarboxylic acid.
• the working life of the solution according to the invention which, in contrast to cyanide baths, can be employed under any conditions, thereby is lengthened considerably.
• the intermediary bath as well as the ensuing treatment according to the invention can be carried out at temperatures ranging from 10 to 90 C. preferably 20 to C. and especially at room temperature.
• the treatment in the intermediary bath as well as the ensuing treatment according to the invention can be carried out for a period of 1 to 15 minutes, preferably 2 to 10 minutes.
• Example 1 Sheet iron was well degreased, etched with 10% aqueous HCl containing 6% ferrochloride, and rinsed. They then were immersed for 2 minutes in a 2% aqueous solution of a mixture consisting of 40 parts by weight NaOH, 40 parts by weight triethanolamine, and 20 parts by weight tetrasodiumethylene diamine tetraacetate. Passivation was carried out immediately thereafter, without an intermediary rinse, in a customary passivating bath (1% aqueous solution composed of 60 parts by weight soda and 40 parts by weight trisodium phosphate; temperature 80 C). The sheets thus obtained were silver-white and could be enameled without exhibiting faults or flaws.
• Example 2 Well degreased steel sheets were etched in a bath of 10% aqueous sulfuric acid containing 50 g./l. iron for 10 minutes at a bath temperature of 60 C. by immersion, and then rinsed with water. Thereafter the sheets were put into an alkaline intermediary bath at room temperature for minutes. This bath consisted of a 2% aqueous solution of equal parts by weight NaOH, soda and triethanolamine. Good agitation was provided. Afterward the sheets were dipped into a 4% aqueous solution consisting of 30 parts by weight NaOH, 5 parts by weight ethylenediamine tetraacetic acid and 65 parts by weight triethanolamine at a temperature of 25 C. and left therein for 2 minutes. The sheets thereafter had a silver color which did not change during and after the passivating treatment as described in Example 1. These sheets were enameled without flaws.
• Example 3 Degreased iron sheets were etched with 15% aqueous HCl and rinsed with water. They then were immersed for 5 minutes in a 3% aqueous solution of 60 C. containing equal parts by weight NaOH, triisopropanolamine and N,N,N,N' tetrakis (Z-hydroxypropyl)-ethylenediamine, and then passivated, without intermediary rinse, in a 0.5% aqueous solution at 80-90 C. containing equal parts by weight soda, phosphate and borax.
• the silver-white surface of the metal sheet contained no residual iron compounds so that the conditions for a flawless enameling were present.
• Example 4 Cold rolled steel sheets were degreased and etched with a 15% aqueous HCl solution containing iron, rinsed, and immersed for 5 minutes in a 3% aqueous solution at 25 C., containing 30 parts by weight NaOH, 30 parts by weight triethanolamine, 30 parts by weight triisopropanolamine and 10 parts by weight tetrasodiumethylenediamine tetraacetate.
• the resulting sheets were silver-white. After ensuing passivation in a conventional bath, as named in Example 1, without an intermediary treatment, these sheets were enameled without exhibiting any flaws or faults.
• Example 5 The following Tables 1 and 2, respectively, show results obtained by treatments under the same conditions but using the indicated pretreatment solutions.
• cold rolled steel sheets were first treated with an alkaline cleanser at 80 C., rinsed and then etched at C.
• etching fluids a 10% aqueous HCl (Process A) or a 10% aqueous sulfuric acid solution (Process B) were employed.
• the etching fluids also contained 4% iron in the form of ferrochloride or ferrosulfate, respectively, and a trace of dibenzylsulfoxide.
• the sheets were rinsed twice with water and then treated at 20 C. with the pretreatment solutions named in the tables.
• the ensuing passivation was effected at C. with a 0.3% aqueous soda solution, and the sheets then were dried at C.
• the treatment time in each bath was 5 minutes, the intervening dwelling times in the air 1 minute.
• EDTA Tetrasodiumethylenediamine tetraacetate.
• Acetophosphonate Acylation products of phosphorous acid with acetyl chloride in the form of their sodium salts (produced according to JACS 34, 492499).
• Polyalkanol N,N,N,N tetrakis (2-hydroxypropyl)- ethylenediamine.
• Silver-white metal Silver-white metal surface.
• A- process for the treatment of iron and steel sheet, after acid etching and prior to passivation preparatory to vitreous enameling, for the purpose of total removal of iron salts formed which comprises exposing said sheet to a 1 to percent by Weight aqueous solution of a mixture consisting essentially of an alkali, selected from the group consisting of sodium hydroxide, potassium hydroxide, soda, potassium carbonate and combinations thereof, with an aliphatic alkanolamine having an alkyl radical of 2 to 4 carbon atoms and at least 3 alkanol groups in its molecule, for a period of 1 to minutes and at a temperature ranging from 10 to 90 C.; said solution having a pH above 10; the alkali constituting more than 25 and up to 50 percent by weight and the alkanolamine the remainder of said mixture.
• a process for the treatment of iron and steel sheet, after acid etching and prior to passivation preparatory to vitreous enameling, for the purpose of total removal of iron salts formed which comprises exposing said sheet to a 1 to 5 weight percent aqueous solution of a mixture consisting essentially of a mixture of an alkali, selected from the group consisting of sodium hydroxide, potassium hydroxide, soda, potassium carbonate and combinations thereof, with an aliphatic alkanolamine having an alkyl radical of 2 to 4 carbon atoms and at least three alkanol groups in its molecule, and a compound selected from the group consisting of nitriloacetic acid, ethylenediaminetriacetic acid, ethylenediaminotet-raacetic acid and their water-soluble salts, for a period of 2 to 10 minutes and at a temperature ranging substantially from to 60 C.; the alkali constituting more than and up to 50 weight percent; the compound up to 20 weight percent, based upon the total amount of the compound taken

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• ing And Chemical Polishing (AREA)
• Detergent Compositions (AREA)
• Chemical Treatment Of Metals (AREA)

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• 1963
  • 1963-01-29 DE DEH48090A patent/DE1216066B/de active Pending
  • 1963-04-09 DE DEH48800A patent/DE1223656B/de active Pending
• 1964
  • 1964-01-22 US US339338A patent/US3317340A/en not_active Expired - Lifetime
  • 1964-01-22 US US339318A patent/US3368913A/en not_active Expired - Lifetime
  • 1964-01-27 LU LU45305D patent/LU45305A1/xx unknown
  • 1964-01-27 BE BE642989A patent/BE642989A/xx unknown
  • 1964-01-28 CH CH620567A patent/CH456295A/de unknown
  • 1964-01-28 GB GB3514/64A patent/GB1042122A/en not_active Expired
  • 1964-01-28 GB GB54820/65A patent/GB1042690A/en not_active Expired
  • 1964-01-28 NL NL6400656A patent/NL6400656A/xx unknown

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