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
  • C23F11/12—Oxygen-containing compounds
  • C23F11/124—Carboxylic acids

Definitions

• the invention relates to an aqueous treatment liquid for corrosion protection of metal surfaces containing salts of one or more aliphatic carboxylic acids with 6 to 10 carbon atoms (component a) and salts of one or more polyoxycarboxylic acids with 6 to 8 carbon atoms (component b). and a concentrate for their manufacture.
• corrosion-protecting additives To protect metallic surfaces against corrosion when in contact with aqueous liquids or when storing metal parts after treatment with aqueous liquids, it is customary to add corrosion-protecting additives to the water.
• various metals are often to be protected by an addition.
• anti-corrosion additives must be readily soluble and stable in water of various degrees of hardness and insensitive to elevated temperatures. They should have a protective effect even at low doses. On the other hand, they must not be toxic, harmful to sewage or irritating to the skin and must not have a strong intrinsic odor.
• EP-PS 0 020 042 describes a corrosion protection agent which contains 5 to 20% by weight of aliphatic monobasic acid with 8 to 20 C atoms, 0 to 4% by weight of lubricant, 10 to 35% by weight of aromatic mono- or Polycarboxylic acid and an amine, which forms a water-soluble salt with the aliphatic and aromatic acid.
• an anticorrosive agent which contains 50 to 100 parts of a salt of a saturated carboxylic acid having 6 to 18 carbon atoms with an amine having 6 to 12 carbon atoms and 20 to 200 parts Alkali metal benzoate and 1 to 50 parts of alkanolamide as a reaction product of ethanolamine and a saturated fatty acid having 6 to 18 carbon atoms.
• an aqueous treatment liquid for corrosion protection of metal surfaces which contains a reaction product of aliphatic carboxylic acids with 6 to 10 carbon atoms and of polyoxycarboxylic acids, such as gluconic acid or tartaric acid, with an alkanolamine.
• treatment fluids for corrosion protection of metals can reduce the corrosion of steel and cast iron, but do not adequately protect other metals.
• Corrosion protection agents based on mercaptobenzthiazole or benzotriazole are common for copper and brass. However, their effect is greatly reduced in numerous mixtures for the corrosion protection of steel.
• multimetal systems e.g. used in hydraulics or in the cooling of large internal combustion engines, including oil emulsions.
• oil emulsions have many disadvantages that limit their use.
• the emulsion decomposes in hard water, the concentrate is flammable and it is not possible to drain it without prior special processing (separation of oil).
• the object of the invention is to provide an aqueous treatment liquid for corrosion protection of metal surfaces or a concentrate for their production, which does not have the known, in particular the aforementioned disadvantages.
• the aqueous treatment liquid mentioned at the outset is designed in accordance with the invention in such a way that it has an additional salt content of one or more aromatic monocarboxylic acids (component c) and the salt-forming cations are predominantly alkali ions.
• the combination of the components of the treatment liquid has a synergistic effect in that significantly better corrosion protection values are obtained than can be achieved with one of the components alone or in combination with only one further component. It is also surprising that - to use organic inhibitors in the form of alkanolamine salts of the acids, contrary to the usual recommendation - especially alkaline salts are effective in the present case 'particularly.
• the molar ratio of the individual components can vary within a wide range and essentially depends on the metals to be protected against corrosion.
• the concentration used and the conditions of use also play a certain role.
• the aqueous treatment liquid contains as component a) salt of caprylic acid and / or xthylhexanoic acid, as component b) salt of gluconic acid and / or heptonic acid and as component c) salt of benzoic acid.
• ammonium ion content should not exceed 20% of the total cation content.
• a further improvement in the properties can be achieved if the treatment liquids according to the invention have an addition of nonionic surfactants with a cloud point below 30 ° C.
• nonionic surfactants are water soluble at low temperatures. When the cloud point is reached, the solutions begin to become cloudy and the foaming effect of the surfactant solution is noticeably reduced.
• These surfactants improve the wetting of the metal surface, so that the treatment liquid can also act on moderately greased or contaminated parts.
• Polyglycol ethers of fatty alcohols, fatty amines and polyamines and polyglycol esters of fatty acids which have been reacted with ethylene oxide and propylene oxide have proven particularly useful. High-molecular block polymers made of polypropylene glycol, condensed with polyethylene oxide, and made of polyethylene glycol, condensed with propylene oxide have an optimal effect.
• corrosion inhibitors for individual metals can also be introduced into the treatment liquids according to the invention, provided that they are compatible with one another in aqueous solution and do not impair the corrosion protection of other metals.
• corrosion inhibitors are, for example, boric acid esters, higher salts Carboxylic acids, salts of amino acids, salts of sulfonamido carboxylic acids and fatty acid alkanolamides.
• Treatment liquids containing mercaptobenzthiazole, benzotriazole and their derivatives are particularly advantageous for the treatment of copper or brass.
• biocides such as phenol derivatives, formaldehyde-releasing compounds, triazines and quaternary ammonium compounds.
• the most favorable values with regard to corrosion protection are achieved when the treatment liquids with which the metals are in contact with components a), b) and c) in a total amount of 0.2 to 4% by weight, preferably 0.5 to 2% by weight.
• the pH of the ready-to-use treatment liquid is expediently in the range from 7 to 10, preferably 8 to 9.
• the easiest way to prepare the salts used in the treatment liquid is to simply mix the organic acids with alkalis and water at temperatures of 40 to 90 ° C.
• the treatment fluids for corrosion protection can be made from a solid salt mixture.
• a liquid concentrate is preferred for the batch, since the treatment liquid can be prepared from it in the simplest manner by dilution.
• Concentrates which contain components a), b) and c) in a total concentration of 30 to 80% by weight, dissolved in water, are particularly suitable.
• the surfactant content of the concentrate is 0.5 to 10 G ew .-%, preferably 1 to 4 wt .-%.
• Sample sheets (100x20x1 mm) made of steel, aluminum, copper, brass (70/30) and zinc in water of 22.4 ° dH (adjusted with calcium chloride) were immersed in half with the addition of corrosion inhibitors and covered in beakers, covered with watch glass, Stored for 28 days at a temperature of 35 ° C. After the test, the samples were rinsed, dried and the weight difference determined.

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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)

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Citations (6)

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• 1982
  • 1982-06-26 DE DE19823223940 patent/DE3223940A1/de not_active Withdrawn
• 1983
  • 1983-06-15 EP EP83200876A patent/EP0099598A1/fr not_active Withdrawn
  • 1983-06-22 CA CA000430914A patent/CA1219119A/fr not_active Expired
  • 1983-06-23 GB GB08317084A patent/GB2122598B/en not_active Expired
  • 1983-06-24 BR BR8303394A patent/BR8303394A/pt unknown
  • 1983-06-24 ZA ZA834632A patent/ZA834632B/xx unknown
  • 1983-06-27 NZ NZ204711A patent/NZ204711A/en unknown
  • 1983-06-27 AU AU16295/83A patent/AU561560B2/en not_active Ceased
  • 1983-06-27 JP JP58115734A patent/JPS5925977A/ja active Pending

Patent Citations (6)

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