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
  • C23F11/10—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 using organic inhibitors
  • C23F11/16—Sulfur-containing compounds
  • C23F11/164—Sulfur-containing compounds containing a -SO2-N group

Definitions

• the invention relates to the use of special sulfonamidocarboxylic acids in the form of the alkali or alkanolamine salts as corrosion inhibitors in aqueous systems.
• DE-A1-33 30 223 describes the salts of the reaction products of alkylbenzenesulfonyl chlorides with glycine or methylglycine as corrosion inhibitors in aqueous systems.
• the properties of the sulfonamido carboxylic acids described above as corrosion inhibitors are not always optimal.
• the actual corrosion protection effect is often too low, so that relatively large amounts have to be used.
• the foaming is too high and the water solubility and water hardness sensitivity, which are of considerable importance, may leave something to be desired.
• the toxicity of the substances used can also play an important role.
• the aim of the present invention is, in particular, to show substances which, in addition to low toxicity in aqueous systems, in addition to good corrosion protection, ensure low foam and low sensitivity to water hardness.
• R1 and R2 represent a phenyl radical which may be mono- or disubstituted by an alkyl radical having 1 to 6 carbon atoms and represent n 0, 1 or 2 and m 1 or 2, in the form of an alkali or an alkanolamine salt.
• the invention also relates to a method for preventing corrosion in aqueous systems by adding a compound of the formula I in the form of an alkali metal or alkanolamine salt to the aqueous system as a corrosion inhibitor.
• the salts of the formula I can also be used in the form of their mixtures.
• Alkyl radicals with 1 to 6 carbon atoms, through which the phenyl radicals can be mono- or disubstituted, are, for example, methyl, ethyl, propyl, i-propyl, butyl, pentyl, hexyl.
• the higher alkyl radicals with 3 to 6 carbon atoms are particularly suitable for simple substitution.
• R 1 and R 2 are phenyl or tolyl and n is 0 and m is 1 or 2.
• Preferred tolyl radicals are the o- and p-tolyl radicals.
• the alkali metal salts are the sodium and potassium salts and the alkanolammonium salts are the salts of mono-, di- or tri-hydroxyalkylamines having 2 to 4 carbon atoms in the hydroxyalkyl radical and mono- (C2-C4) - hydroxyalkyl-mono- or -dialkylamines having 1 to 4 carbon atoms in the alkyl radical and di- (C2-C4) -hydroxyalkyl-mono- (C1-C4) alkylamines.
• Preferred alkanolamines are mono-, di- and triethanolamine, mono-, di- and trihydroxyisopropylamine as well as N-methyldiethanolamine and dimethyl-monoethanolamine.
• they are also their mixtures, as are obtained in industrial production.
• the acids of the formula I are known in principle from the literature and can be prepared by processes known per se.
• the use of their alkanolamine salts as corrosion inhibitors is by no means apparent from the literature.
• the acids of formula I are conveniently with the above.
• the sulfonamide nitrogen atom has a hydrogen atom or an alkyl radical, preferably methyl, as a substituent.
• the compounds of the formula I to be used according to the invention have an aromatic radical or aromatic substituted alkyl radical on the nitrogen atom corresponding to the meanings of R 1 and n.
• the present invention makes the sulfonamido carboxylic acids substituted by aromatic radicals technically usable for the first time. Since corrosion inhibition and foaming behavior are very sensitive and unpredictable properties, the superior effects are not obvious, despite the relatively small structural differences.
• the corrosion inhibitors according to the invention can be used in all aqueous systems which come into contact with iron, its alloys (steels), aluminum, its alloys, zinc or copper and their alloys.
• aqueous systems which come into contact with iron, its alloys (steels), aluminum, its alloys, zinc or copper and their alloys.
• Examples include Hydraulic fluids, cooling lubricants, neutral to alkaline technical cleaners, cooling water additives, coolant or pit water, which are particularly hard and salt-rich and which are used directly in mining as mixing water e.g. are used for hydraulic processes and are particularly corrosive.
• the aqueous systems have a suitable pH range from 8.0 to 8.8.
• concentrations in practical use fluctuate depending on the area of application and the type of aqueous medium and the metals to be protected. In general, based on the aqueous system, 0.01 to 5% by weight is used. Falling below this limit generally reduces the protective effect, exceeding this does not result in any additional advantages.
• the concentration is preferably 0.1 to 2% by weight.
• the corrosion protection effect is determined in accordance with DIN Test 51360, Part 2.
• the sulfonamidocarboxylic acid to be investigated is mixed with such an amount of triethanolamine (TEA) that a 1% by weight aqueous solution has a pH of 8.2 ⁇ 0.1.
• TAA triethanolamine
• Table 2 shows the results obtained, which contain a comparison with N-methyl-benzenesulfonamidocaproic acid (commercially available).

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Lubricants (AREA)
• Detergent Compositions (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Citations (6)

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• 1987
  • 1987-06-06 DE DE19873719046 patent/DE3719046A1/de not_active Withdrawn
• 1988
  • 1988-05-31 EP EP88108665A patent/EP0294687B1/fr not_active Expired - Lifetime
  • 1988-05-31 DE DE88108665T patent/DE3884277D1/de not_active Expired - Lifetime
  • 1988-06-06 US US07/202,244 patent/US4911888A/en not_active Expired - Fee Related
  • 1988-06-06 JP JP63137612A patent/JPS6415385A/ja active Pending

Patent Citations (6)

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