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 preparation of metal sheets for the application of vitreous enamels. More particularly, it relates to an etching treatment with polyhydroxycarboxylic acids or their salts, respectively, yielding silverwhite metal surfaces,
• This process provides for an etching of the metal surfaces and a prior treatment with solutions containing polyhydroxy-carboxylic acids, preferably containing at least 3-hydroxyl groups in their molecules, or with acids having the generic Formulae 1 or 2, respectively.
• the metal sheets are passivated in the conventional manner with alkaline solutions.
• the hydroxyor amino-diphosp'honic acids according to Formula 1 can 'be produced either by the reaction of mon-ocarboxylic acid anhydrides and/or chlorides with phosphorous acid or else according to the process disclosed in German Patent 1,002,355.
• the hydrocarbon radical R may be an alkyl radical having 1 to 8 carbon atoms or an aromatic radical.
• the bydroxyor amino-tetraphosphonic acids of Formula 2 can be produced in a similar manner, whereby, however, in lieu of the monocarvboxylic anhydrides or chlorides, the corresponding dicarboxylic acid derivatives are used, or in the case of aminotetraphosphonic acids, organic dinitriles, opportunely approximately 4 mols phosphorus trihalide per mol dinitrile.
• Polyhydr-oxycarboxylic acids applicable to the process according to the invention are compounds having th formulae CH OH (CHOH 3 -COOH CH OH(CHOH) COOH, COOH(CHOH) 3 COOH and COOH(CHOHMCOOH Particularly readily available and especially suited for the process are gluconic acid, saccharic acid and glucosacc'haric acid.
• water-soluble salts can be employed, e.'g., the sodium-, potassiumor ammonium salts, and also ethanolamine salts.
• the latter are obtained by a partial or total neutralization of the acids.
• solutions are used whose concentrations lie between 0.1 and 10 percent by weight, and preferably 1 to 5 percent and the treatment generally is carried out at temperatures ranging from 5 to 90 C. It technologically is of advantage that this pretreatrnent can be carried out preferably at low temperatures, i.e., at a range of 5-40 C., and especially at room temperature.
• the treatment in the bath can be carried out for a period of 1 to 15, preferably 3 to 5 minutes.
• Passivation of the metal surfaces is effected in a conventional manner.
• passivation baths of alkaline solutions which contain alkalihydroxides, soda, phosphates, boraX and nitrites, singly or in mixture.
• Passivation generally is carried out at 50 to 100 0, preferably at to C.
• the concentration of the passivating baths is 0.3 to 3 percent by weight,- preferably 0.5 to 1.5 percent.
• a special embodiment of the process according to the invention consists in effecting the etching not with hydrochloric, sulfuric or phosphoric acid, if desired, in the presence of inhibitors, as is customary, but instead with the acids of the Formulae 1 or 2 named above. These acids are applied in concentrations of 2 to 20 percent by weight at 40 to 90 C. and a period of 3 to 15 minutes. When these acids are used, etching and the pretreatment prior to enameling can be carried out in a single step.
• an intermediate treatment after etching with solutions of metal salts whose metal ions are more noble than the metal sheet to be enameled. If iron and steel are to be enameled, solutions are applicable containing nickel, cobaltor copper salts.
• concentration of the solu tions range from 0.5 to 3 percent by weight.
• This intermediate treatment generally is carried out at tempera tures ranging from 5 to 90 C. preferably 50 to 70 C.
• the treatment in the intermediary bath can be carried out for a period of 3 to 15 minutes.
• Example 4 fi 33 3 2 f g if f gfifi g: Well degreased iron sheets were etched in a 10 percent 3 g g"; f :3 i In 1 w S of illus HCl solution containing 6 percent ferrochloride, rinsed i s; not of eitation g s; i g g Chan 8 with water, and then immersed for approximately 5 minma made fi detail with ut awn fro a; utes in a 2 percent by weight aqueous solution of 50 s iryit 3 g f "i r weight parts aminopropane-l,l-diphosphonic acid and 50 cfaimed pe e 1 10 as B em I weight parts hydroxyethane-1,1-diphosphonic acid at ap- Exam 1e 1 proximately C.
• Silverwhite sheets thus were obtamed which then were passivated without intermediary Well degreased steel sheets were etched in a 10 percent 2 rinsing at 80-90 C. in a solution as named in Example by weight sulfuric acid solution containing 50 g./l. iron, 0 1.
• the silverwhite sheets had no more iron compounds at a bath temperature of 60 C., 'by immersion for 5 minon their surfaces and exhibited no flaws when enameled. utes, and then rinsed in water. Thereafter, the sheets N i i ti f i h d id could be observed were immersed for 4 minutes in a 2 percent by weight aqued i passivation.
• ous solution of equal Weight parts gluconic acid and hy- 25 Example 5 droxyethane-1,1-diph0sphonic acid at room temperature.
• aqueous sulfuric acid containing g./l. iron, weight parts soda, phosphate andborax.
• tihe P131 rinsed in water and immersed for 5 minutes in a 2 perslveitlon tll li i ih i t a td gfe siligiiziliite and 5 Cent by weight aqueous hydroxyethane-l,l-diphosphonic sur aces 0 e s ee acid solution at room temperature.
• the sheets then were no flaws occurred upon enamelmg.
• Example 3 Example 1, at -90 C.
• the surfaces of the silverwhite W n degreased steel h t were t h d i h a 10 sheets thus obtained contained no iron compounds and percent sulfuric acid solution containing 50 g./ 1. iron at a 50 lent themselves to flawless enameling.
• diphosphonic acid (calc. as free acid). 2 Lactic acid 2 Oxidic discoloration after Oxidic discoloration after passivation. passivationv 1 Ethylenediaminetetraacetic acid 4 do Do. 2 Monosodiumnitrilotriacetic acid 12 d0 Do.
• Example 7 In the accompanying Table 1, results are listed as obtained with different pretreated solutions, as named, at otherwise like procedures and using like metal sheets.
• cold rolled iron sheets first were treated at 80 C. with an alkaline cleanser, rinsed with water, and then etched at 50 C.
• etching solutions a percent by weight aqueous HCl solution (process A) or a 10 percent by weight aqueous sulfuric acid solution (process B) were employed.
• process A the solution also contained 4 percent by weight FeCl '4H O and 1 g./l. dibenzylsulfoxide as inhibitor.
• process B 10 percent by weight FeSO -7H and 1 g./l. dibenzylsulfoxide were added to the etching solution. After etching by either method, the sheets were rinsed twice, whereby the pH in the first rinsing step was 1, in the second step 7.
• the treatment time in each bath was 5 minutes, the intervening dwelling times in the air 1 minute.
• Example 11 Well degreased iron sheets were rinsed with water and then etched for 5 minutes in a 10 percent by weight aqueous aminoethane-1,1-diph0sphonic acid solution at 60 C. Upon ensuing passivation, without intermediary rinsing, in a solution as described in Example 10, no precipitation of basic metal salts occurred. The sheets, after drying, showed a weakly bluish tempering color.
• a process for the pretreatment 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 for 1 to 15 minutes and at temperatures ranging from 5 to 90 C. to a 0.1 to 10 percent by weight aqueous solution of a compound selected from the group consisting of polyhydrocarboxylic acids having the formulae CH OH (CHOH) 3 COOH,
• Example 8 Well degreased steel sheets were etched for 5 minutes in a 10 percent by weight aqueous sulfuric acid solution containing 50 g./1. iron and 1 g./l. dibenzylsulfoxide as inhibitor, at a bath temperature of 60 C., then rinsed with water. Thereafter, the sheets were treated for 10 minutes at 70 C. with a solution (series A) of 12 g./l. NiSO -H O in water, or (series B) of 15 g./l. CuSO -5H O in water.
• Table 2 shows that in all instances when the pretreatment solutions as named were applied, metal surfaces were obtained which facilitated flawless vitreous enameling. This was not the case when the pretreatment according to the invention was omitted.
• Example 9 Well degreased iron sheets were rinsed with water and etched in a 7.5 percent by weight aqueous solution of hydroxyethane-l,l-diphosphonic acid at 60 C. for 5 minutes. The sheets then were passivated as described in the preceding example. They could be enameled without exhibiting any flaws.
• Example 10 Well degreased iron sheets were rinsed with water and etched for 5 minutes in a 5 percent by Weight aqueous solution of 1,3-dihydroxypropane-1,1,3,3-tetraphosphonic acid at 60 C. Passiv-ation followed without intermediary rinse, in a conventional bath consisting of a 1 per- Cir COOH(CHOH) -COOH, COOH(CHOH) COOH,.
• gluconic acid saccharic acid, glucosaccharic acid, acids havwherein R is selected from the group consisting of a hydrocarbon radical having 1 to 8 carbon atoms and a phenyl radical; n is a Whole number from 1 to 8; and X is selected from the group consisting of -OH and -NH water soluble salts of all those acids, and mixtures thereof.

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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 US339318A patent/US3368913A/en not_active Expired - Lifetime
  • 1964-01-22 US US339338A patent/US3317340A/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 NL NL6400656A patent/NL6400656A/xx unknown
  • 1964-01-28 GB GB54820/65A patent/GB1042690A/en not_active Expired

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