EP0609342B1 - Composition for stabilizing inorganic peroxide solutions - Google Patents

Composition for stabilizing inorganic peroxide solutions Download PDF

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Publication number
EP0609342B1
EP0609342B1 EP92922319A EP92922319A EP0609342B1 EP 0609342 B1 EP0609342 B1 EP 0609342B1 EP 92922319 A EP92922319 A EP 92922319A EP 92922319 A EP92922319 A EP 92922319A EP 0609342 B1 EP0609342 B1 EP 0609342B1
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Prior art keywords
composition according
composition
treatment
stabilizing
test
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German (de)
French (fr)
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EP0609342A1 (en
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Costante Fontana
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Solvay Interox SpA
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Solvay Interox SpA
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    • 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
    • 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
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/10—Etching compositions
    • C23F1/14—Aqueous compositions
    • C23F1/16—Acidic compositions
    • 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
    • C23F3/00—Brightening metals by chemical means
    • C23F3/04—Heavy metals
    • C23F3/06—Heavy metals with acidic solutions

Definitions

  • the present invention relates to a composition having high stabilizing properties, more particularly in the case of inorganic peroxides used in the context of industrial applications.
  • It relates more particularly to a stabilizing composition of inorganic peroxides used in the pickling baths of metal surfaces.
  • Strippers of the type mentioned generally contain nitric-hydrofluoric mixtures or mixtures of sulfuric-nitric and hydrofluoric acids, to which process correctors which may be surfactants have been added, in order to improve their wetting characteristics or inhibitors for standardize the chemical action.
  • pickling baths have recently been proposed. which provide an alternative solution to traditional processes.
  • the auxiliary mechanical action normally provides for the creation of turbulence in the pickling solution, either by stirring the liquid or by blowing air into the baths so as to promote the detachment of the oxides from the metal surfaces.
  • the absence of nitric acid in these baths is compensated for by the presence of inorganic peroxides such as hydrogen peroxide.
  • inorganic peroxides not only replaces the oxidizing action of nitric acid, but it also promotes pickling and passivation of the metal surface.
  • control of the peroxides present in the baths should normally be carried out using redox measuring instruments which, as is known, are not only very expensive to purchase, but also have a limited longevity when they are used for this specific purpose.
  • the baths containing peroxides also offer limited stability, due to the presence of metals which catalyze the decomposition of the peroxides.
  • nitric acid-free baths allow for the moment to considerably reduce the degree of pollution, on the other hand, it is necessary either to operate at temperatures generally higher than the temperatures usual, either to carry out costly modifications of the equipment, the latter having to be equipped with means for heating and agitating the baths or means for blowing air into these same baths, and therefore providing for automatic control and permanent peroxide contained in the pickling mixture.
  • peroxidized chemical attack compositions of effective metals must contain a certain amount of 3-amino-1,2,4-triazole, a constituent which acts both as an accelerator of chemical attack and as stabilizer (page 2, lines 20 to 26).
  • an important objective of the present invention is to produce a composition having high stabilizing properties, and this, more particularly with regard to the inorganic peroxides used in the context of industrial applications, this composition having to be able to stabilize peroxides while avoiding undesirable decompositions of these same peroxides in the presence of metals, even in high concentrations, and more specifically in the context of acid pickling processes replacing nitric mixtures.
  • Another important objective of the present invention is to provide a composition offering high stabilizing properties and capable of increasing the oxidation action of peroxides, more particularly hydrogen peroxide in contact with surfaces metallic, and this by means of an oxidation-dissolution action of oxides which is extremely rapid, even at room temperature.
  • Another important objective of the present invention consists in producing a composition offering high stabilizing properties and which is capable of providing a pickling system which would replace the nitric acid baths currently used, without however the need to modify the equipment used and without reducing the treatment time at the same temperature.
  • Another objective - and not least - of the present invention is to provide a composition with high stabilizing properties which makes it possible to eliminate the heating of the solutions and to eliminate their agitation as well as the permanent control of the level of peroxides contained in the baths. .
  • the invention relates to a stabilizing composition for inorganic peroxides intended for baths for the surface treatment of metal parts, according to which it comprises at least one activating agent selected from benzotriazoles, imidazole and carboxyimidazoles or their derivatives.
  • composition with high stabilizing properties in particular for the inorganic peroxides used in the context of 'applications industrial.
  • inorganic peroxides is intended to denote hydrogen peroxide, inorganic peracids and their salts, more particularly perboric, perphosphoric and persulfuric acids and their alkali or alkaline earth metal salts, as well as peroxides of alkali and alkaline earth metals such as sodium, calcium and magnesium peroxides.
  • hydrogen peroxide or inorganic peracids are used. Very good results have been obtained with hydrogen peroxide.
  • surface treatment of metal parts is intended to denote the treatment of metal parts using a bath comprising one or more acidic compounds and one or more oxidizing compounds, in particular with a view to stripping them by removing the oxides covering their surface, or passivate them or improve the surface finish, more particularly to polish them and / or perform a polishing treatment.
  • the composition is intended to be incorporated into the surface treatment baths of metal parts. It generally does not itself contain peroxide, which is added to the treatment bath independently.
  • the stabilizing action of peroxides and their capacity to accelerate deoxidation depend on the composition of the baths in which the traditional standard nitric-hydrofluoric mixture is replaced, as regards the nitric part, by oxygenated water in the H2O2-HNO3 molar proportion of 1/2 to 2/1 but preferably 1/1, while the acid part of the nitric acid is replaced by sulfuric acid in the HNO3-H2SO4 molar proportion of 1 / 2 to 2.5 / 1, but preferably 1 / 1.3.
  • the acid part with regard to sulfuric acid may be replaced, in whole or in part, by inorganic acids of phosphoric, sulfamic or other type, insofar as they do not cause a negative interaction with the stabilizer of the hydrogen peroxide or peroxide.
  • the hydrofluoric part can for its part comprise at least one compound chosen from fluorinated acids or fluorinated salts and the percentage is maintained within the usual standard values that are known.
  • the bath thus obtained requires the presence of a peroxide stabilizing agent in the proportion of 1/100 to 1/1, but preferably from 1/30 to 1/2, depending on the peroxide used.
  • the stabilizing agent used for the baths of these compositions and which constitutes the object of the present invention can comprise, in addition to the activating agent at least, another compound chosen from stabilizing agents, the solvent compounds of the stabilizing agent, oxidation catalysts, wetting agents capable of resisting in an oxidizing acid environment, optionally phosphates or phosphonates as co-adjuvants for precipitation and deactivation of dissolved metals, and finally, inorganic and / or organic acids as product standardizers.
  • the composition also comprises at least one stabilizing agent.
  • the stabilizing agent in particular, it may comprise one or more aromatic or cyclic rings or one or more aliphatic chains. It can also contain at least one group chosen from hydroxyl, carboxylic, sulfonate and phosphate groups.
  • the term “sulfonate and phosphate groups” is intended to denote here both the sulfonic and phosphoric groups and their salts. It can also contain at least one group chosen from esters, ethers, dienes, azoles, mercapto-azoles or combinations thereof.
  • the stabilizing agent may comprise at least one compound selected from mono or polycyclic aromatic or alicyclic compounds and aliphatic compounds substituted by at least one group chosen from the groups hydroxyls, carboxyls, sulfonates, phosphates, esters, ethers, dienes, azoles and mercapto-azoles. Good results have been obtained with compounds substituted by sulfonate (or sulfonic) groups and phosphates (or phosphoric) groups or mixtures thereof. P-Toluene sulfonic acid is well suited.
  • compositions according to the invention can comprise at least one solvent compound for the stabilizing agent.
  • the solvent compound also called dissolving part of the stabilizing agent described above can include alcohols, glycols, polyethers, dimethylformamide, N-methylpyrrolidone, ketones, polyglycols, esters, low-weight condensates molecular or organic groups characterized by a reasonable solubility in water, resistant in an acidic environment and having a good dissolving power of the organic components used as stabilizing agents and having zero or low solubility in water or in inorganic acids at use concentrations.
  • the solvent compound of the stabilizing agent preferably comprises at least one compound selected from alcohols, glycols and polyglycols.
  • the solvent compound can also contain, in admixture with said alcohols, glycols and / or polyglycols at least one adjuvant chosen from dimethylformamide and N-methylpyrrolidone.
  • the solvent compound can include polyesters, ketones, esters, low molecular weight condensates or organic groups with good water solubility and resistance in an acidic medium.
  • the activating agent which can also also be used independently of the stabilizing agents or solvent compounds mentioned above, comprises cyclic, aromatic amine components, derivatives of imidazoles and / or carboxy-imidazoles, and / or aliphatic amines.
  • compositions according to the invention can also contain at minus one compound chosen from oxidation catalysts made up of metals and wetting agents resistant in an oxidizing acid medium.
  • the oxidation catalysts can comprise at least one metal belonging to the first, second, third or fourth group. These are present in a percentage varying from 2 to 20,000 ppm and preferably from 10 to 3,000 ppm.
  • group is meant a group which corresponds to a family represented in the same column of the periodic table of the elements.
  • the metals of group 3 have proved to be interesting and good results have been obtained with aluminum.
  • the composition may also comprise at least one wetting agent stable in oxidizing acid medium, that is to say an agent capable of modifying the surface tension at the solid / liquid interface in order to improve the wetting of metal parts by the treatment bath.
  • This wetting agent should be selected from those which are chemically inert in the presence of an acidic and oxidizing aqueous solution and, in particular, acidic aqueous solutions of peroxides.
  • wetting agents capable of resisting in an oxidizing acid environment consist of nonionic, anionic, amphoteric or cationic condensates or fluorinated derivatives, or a mixture of these. Good results have been obtained with fluorinated anionic surfactants and ethylene glycol condensates with alkylphenols and their mixtures.
  • the pickling bath constituted in this way and having the stabilizing agent described above can operate from a pH equal to 2.5 and up to a pH of 0.0, but usually it operates at a pH below 1.3.
  • the pickling bath can operate at pH values equal to or less than 0.3.
  • the stabilizing composition reduces the oxidation potential of the iron / nickel / chromium sub-oxides and catalyze their oxidation, thereby promoting the transformation into soluble oxides.
  • the presence in a pickling bath of the stabilizing composition which is the subject of the present invention makes it possible to carry out pickling in a time and at extremely competitive temperatures compared to the baths currently used.
  • composition according to the invention it is also possible to incorporate precipitation additives and, consequently, deactivation of the dissolved metals originating from the dissolution of the oxides or from the surface part of the metal part under the action of the treatment bath.
  • adjuvants can be soluble inorganic or organic salts whose anion combines with the cation of the metal or metals dissolved in the bath to form a salt whose solubility product is very low under the conditions prevailing in the bath, for example less than 10 ⁇ 5 gram ion.
  • the composition can also comprise at least one compound chosen from phosphates and phosphonates as co-adjuvants for precipitation and deactivation of dissolved metals and inorganic and organic acids as treatment-leveling agents. These are used to standardize the product.
  • the precipitation co-adjuvants can be chosen from phosphates and phosphonates of all types. Pyrophosphates are well suited.
  • the stripping action obtained through the use of the composition having high stabilizing properties and which is the subject of the present invention normally does not require any agitation of the baths or of the elements which are immersed therein.
  • the invention therefore therefore also relates to methods for treating metallic surfaces, more particularly stainless steel surfaces in the presence of the stabilizing compositions described above using at least one inorganic peroxide at acid pH. This treatment is then followed by at least one rinsing. During at least one of the treatment or rinsing phases, agitation of the bath can be obtained using ultrasound.
  • variable doses of the various active compounds and in particular of acid, of inorganic peroxides and of stabilizing composition according to the invention can be used. It is thus possible to use 0.1 to 5 moles and preferably 0.5 to 3 moles of peroxidized compound per liter of solution.
  • the amount of acid is added to maintain the pH at the desired values.
  • the acids which can be used for this purpose mention may be made of sulfuric acid which is particularly suitable. It can be used in combination with fluorides and for example with hydrofluoric acid in variable ratios. In this case, the sulfuric acid / hydrofluoric acid weight ratios generally do not exceed 500 and, more often than not, 100. Likewise these ratios are generally not less than 0.1 and, most often, not less than 1.
  • the invention also relates to the use of the composition described above for the preparation of a pickling, passivating, polishing and / or polishing bath for metals.
  • a typical composition includes: 98% sulfuric acid from 4 to 300 g / l 100% hydrogen peroxide from 0.2 to 100 g / l hydrofluoric acid from 0.5 to 10 g / l stabilizing composition from 0.2 to 30 g / l where the standard stabilizing composition consists of: p-toluene sulfonic acid 10 N-methylpyrrolidone 22 ethylene glycol 5 benzotriazole + imidazole (about 50% - 50%) 3 aluminum +++ 3 fluorinated anionic surfactant 0.5 (FC R 95: registered trademark of 3M company) ethylene oxide and octylphenol condensate 5 pyrophosphate ion 4 sulfuric acid 10 citric acid 2 water complement to 100
  • Stability tests were then carried out by incorporating into the mixture, consisting of 180 g / l of sulfuric acid, 40 g / l of H2O2 and 30 g / l of hydrofluoric acid, an amount of 8 g / l of AISI 304 steel and then relating the H2O2 content to the initial values.
  • composition of the invention having high stabilizing properties and more particularly in the case of inorganic peroxides used in the context of industrial applications, offers many advantages of all kinds.
  • the temperatures of use of pickling baths appear to be equal to or really lower than the temperatures which are those of baths based on nitric and hydrofluoric acid and therefore, highly polluting.
  • composition having important stabilizing properties, object of the present invention By using in a bath the composition having important stabilizing properties, object of the present invention, there is no emission of nitrous vapors, and the emission of acids, for example fluorides, is itself extremely reduced.
  • Intergranular corrosion is also eliminated, among other things, and the process can be adapted to different types of stainless steels such as, for example, steels from the AISI 400 series (pickling is generally difficult with traditional systems). or still, the steels of the AISI 300 series. It is understood that the compositions according to the invention are also well suited for the treatment of other types of stainless steels.
  • the use of the stabilizing composition described above makes it possible in particular to considerably reduce the consumption of inorganic peroxide, more particularly hydrogen peroxide, while allowing equal or really lower pickling times. , even up to 50%, compared to the stripping times required in the case of traditional baths.

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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)
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  • Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)

Abstract

A composition for stabilizing inorganic peroxides and hydrogen peroxide in metal surface treating baths, including at least one activating agent chosen from cyclic or aromatic amine compounds, triazole, imidazole and carboxyimidazole derivatives and aliphatic amines. A method for treating metal surfaces with the composition having acidic pH and in the presence of inorganic peroxide, as well as the use of the composition to obtain a metal pickling, brightening or polishing bath, are also described.

Description

La présente invention concerne une composition présentant des propriétés stabilisantes élevées, et ce, plus particulièrement dans le cas des peroxydes inorganiques utilisés dans le cadre d'applications industrielles.The present invention relates to a composition having high stabilizing properties, more particularly in the case of inorganic peroxides used in the context of industrial applications.

Elle concerne plus particulièrement une composition stabilisante des peroxydes inorganiques utilisés dans les bains de décapage de surfaces métalliques.It relates more particularly to a stabilizing composition of inorganic peroxides used in the pickling baths of metal surfaces.

Comme on le sait, le traitement de surface des aciers inoxydables prévoit actuellement l'élimination des oxydes par le biais d'un procédé chimique.As is known, the surface treatment of stainless steels currently provides for the elimination of oxides by means of a chemical process.

Parfois, il arrive que ce procédé chimique soit précédé d'une action mécanique, telle que le sablage ou le brossage de l'acier, opération effectuée en vue d'obtenir une amélioration de la surface des aciers de manière à réduire la durée de leur traitement chimique.Sometimes it happens that this chemical process is preceded by a mechanical action, such as sanding or brushing the steel, an operation carried out with a view to improving the surface of the steels so as to reduce the duration of their chemical treatment.

Les bains décapants du type mentionné renferment généralement des mélanges nitrique-fluorhydriques ou des mélanges d'acides sulfurique-nitriques et fluorhydriques, auxquels on a ajouté des correcteurs de processus qui peuvent être des tensioactifs, pour en améliorer les caractéristiques de mouillage ou des inhibiteurs pour uniformiser l'action chimique.Strippers of the type mentioned generally contain nitric-hydrofluoric mixtures or mixtures of sulfuric-nitric and hydrofluoric acids, to which process correctors which may be surfactants have been added, in order to improve their wetting characteristics or inhibitors for standardize the chemical action.

Les traitements de surface des aciers actuellement utilisés étant particulièrement polluants du fait de la présence d'oxydes d'azote qui se développent durant l'action décapante ou du fait des nitrates présents dans les eaux de décharge, on a récemment proposé des bains de décapage qui apportent une solution alternative aux procédés traditionnels.Since the surface treatments of the steels currently used are particularly polluting due to the presence of nitrogen oxides which develop during the pickling action or due to the nitrates present in the landfill, pickling baths have recently been proposed. which provide an alternative solution to traditional processes.

Ces bains opèrent habituellement à chaud et exigent surtout dans le même temps une action mécanique auxiliaire dont l'objectif est de compenser l'absence d'action de désagrégation due à l'absence d'acide nitrique dans ces bains.These baths usually operate hot and especially require at the same time an auxiliary mechanical action whose objective is to compensate for the absence of disintegration action due to the absence of nitric acid in these baths.

L'action mécanique auxiliaire prévoit normalement la réalisation de turbulences dans la solution décapante, que ce soit en remuant le liquide ou en insufflant de l'air dans les bains de manière à favoriser le détachement des oxydes des surfaces métalliques. L'absence d'acide nitrique dans ces bains est compensée par la présence de peroxydes inorganiques tels que l'eau oxygénée.The auxiliary mechanical action normally provides for the creation of turbulence in the pickling solution, either by stirring the liquid or by blowing air into the baths so as to promote the detachment of the oxides from the metal surfaces. The absence of nitric acid in these baths is compensated for by the presence of inorganic peroxides such as hydrogen peroxide.

La présence des peroxydes inorganiques remplace non seulement l'action oxydante de l'acide nitrique, mais elle favorise en outre également le décapage et la passivation de la surface métallique.The presence of inorganic peroxides not only replaces the oxidizing action of nitric acid, but it also promotes pickling and passivation of the metal surface.

Si l'emploi de ces bains décapants exempts d'acide nitrique permet d'une part de résoudre le problème de la pollution due au développement d'oxyde d'azote lors de l'action décapante et le problème entraîné par la présence de nitrates dans les eaux de décharge, il nécessite toutefois l'emploi d'équipements spécifiques, coûteux, et qui requièrent un entretien périodique.If the use of these nitric acid-free pickling baths allows on the one hand to solve the problem of pollution due to the development of nitrogen oxide during the pickling action and the problem caused by the presence of nitrates in Landfill, however, it requires the use of specific, expensive equipment that requires periodic maintenance.

En outre, le contrôle des peroxydes présents dans les bains doit normalement être effectué à l'aide d'instruments de mesure redox qui, comme on le sait, sont non seulement fort coûteux à l'achat, mais présentent également une longévité limitée lorsqu'ils sont utilisés à cette fin spécifique.In addition, the control of the peroxides present in the baths should normally be carried out using redox measuring instruments which, as is known, are not only very expensive to purchase, but also have a limited longevity when they are used for this specific purpose.

Les bains renfermant des peroxydes offrent en outre une stabilité limitée, et ce, du fait de la présence de métaux qui catalysent la décomposition des peroxydes.The baths containing peroxides also offer limited stability, due to the presence of metals which catalyze the decomposition of the peroxides.

Afin d'éviter ces inconvénients, et donc les décompositions indésirables des peroxydes, on inhibe actuellement l'action de dissociation des peroxydes eux-mêmes, ce qui a pour conséquence secondaire une réduction de l'activité chimique du décapage.In order to avoid these drawbacks, and therefore the undesirable decompositions of the peroxides, the dissociation action of the peroxides themselves is currently inhibited, which has the secondary consequence of a reduction in the chemical activity of pickling.

Dans une telle situation et afin de compenser la moindre activité des bains de décapage, il est donc nécessaire d'opérer à des températures supérieures aux températures ambiantes, en procédant en outre à une agitation des bains de manière à favoriser le détachement des oxydes.In such a situation and in order to compensate for the lower activity of the pickling baths, it is therefore necessary to operate at temperatures above ambient temperatures, by additionally agitating the baths so as to promote the detachment of the oxides.

A la lumière de ce qui vient d'être exposé ci-avant, on comprend clairement que, si d'une part, les bains exempts d'acide nitrique permettent pour l'instant de réduire considérablement le degré de pollution, d'autre part, il est nécessaire, soit d'opérer à des températures généralement supérieures aux températures habituelles, soit de réaliser des modifications coûteuses des équipements, ces derniers devant être équipés de moyens de réchauffement et d'agitation des bains ou de moyens pour insuffler de l'air dans ces mêmes bains, et de prévoir, par conséquent, le contrôle automatique et permanent du peroxyde contenu dans le mélange décapant.In the light of what has just been explained above, we understands clearly that, on the one hand, nitric acid-free baths allow for the moment to considerably reduce the degree of pollution, on the other hand, it is necessary either to operate at temperatures generally higher than the temperatures usual, either to carry out costly modifications of the equipment, the latter having to be equipped with means for heating and agitating the baths or means for blowing air into these same baths, and therefore providing for automatic control and permanent peroxide contained in the pickling mixture.

Dans de telles conditions opérationnelles, les bains exempts d'acide nitrique sont encore peu utilisés actuellement, et ce, du fait du coût élevé des équipements mais aussi des problèmes de gestion qu'ils entraînent.Under such operational conditions, nitric acid-free baths are still little used today, due to the high cost of the equipment but also to the management problems which they cause.

Le document FR-A-2513258 enseigne que des compositions peroxydées d'attaque chimique de métaux efficaces doivent contenir une certaine quantité de 3-amino-1,2,4-triazole, constituant qui agit à la fois comme accélérateur d'attaque chimique et comme stabilisant (page 2, lignes 20 à 26).The document FR-A-2513258 teaches that peroxidized chemical attack compositions of effective metals must contain a certain amount of 3-amino-1,2,4-triazole, a constituent which acts both as an accelerator of chemical attack and as stabilizer (page 2, lines 20 to 26).

Le document US-A-4510018 divulgue que des solutions de décapage efficaces du cuivre et des alliages au cuivre comprennent un mélange de peroxyde, d'acide sulfurique et d'une amine d'un acide gras en milieu aqueux (colonne 2, lignes 1 à 8 et revendication 1).Document US-A-4510018 discloses that effective pickling solutions for copper and copper alloys include a mixture of peroxide, sulfuric acid and a fatty acid amine in an aqueous medium (column 2, lines 1 to 8 and claim 1).

Dans cette situation, l'objet technique de la présente invention est de remédier aux inconvénients exposés ci-avant qui font partie intégrante de la technique connue. Dans le cadre de cet objet technique, un objectif important de la présente invention est de réaliser une composition présentant des propriétés stabilisantes élevées, et ce, plus particulièrement en ce qui concerne les peroxydes inorganiques utilisés dans le cadre d'applications industrielles, cette composition devant être à même de stabiliser les peroxydes tout en évitant les décompositions indésirables de ces mêmes peroxydes en présence de métaux, même en fortes concentrations, et plus spécifiquement dans le cadre de procédés de décapage acide remplaçant les mélanges nitriques.In this situation, the technical object of the present invention is to remedy the drawbacks set out above which are an integral part of the known technique. Within the framework of this technical object, an important objective of the present invention is to produce a composition having high stabilizing properties, and this, more particularly with regard to the inorganic peroxides used in the context of industrial applications, this composition having to be able to stabilize peroxides while avoiding undesirable decompositions of these same peroxides in the presence of metals, even in high concentrations, and more specifically in the context of acid pickling processes replacing nitric mixtures.

Prenant en considération cet objet technique, un autre objectif important de la présente invention est de fournir une composition offrant des propriétés stabilisantes élevées et capable d'accroître l'action d'oxydation des peroxydes, plus particulièrement de l'eau oxygénée au contact des surfaces métalliques, et ce, par le biais d'une action d'oxydation-dissolution des oxydes qui soit extrêmement rapide, même à température ambiante.Taking into account this technical object, another important objective of the present invention is to provide a composition offering high stabilizing properties and capable of increasing the oxidation action of peroxides, more particularly hydrogen peroxide in contact with surfaces metallic, and this by means of an oxidation-dissolution action of oxides which is extremely rapid, even at room temperature.

Un autre objectif important de la présente invention consiste à réaliser une composition offrant des propriétés stabilisantes élevées et qui soit à même de fournir un système de décapage qui remplacerait les bains à base d'acide nitrique actuellement utilisés, sans toutefois qu'il soit nécessaire de modifier les équipements utilisés et sans qu'il faille réduire, à température égale, la durée de traitement.Another important objective of the present invention consists in producing a composition offering high stabilizing properties and which is capable of providing a pickling system which would replace the nitric acid baths currently used, without however the need to modify the equipment used and without reducing the treatment time at the same temperature.

Un autre objectif - et non des moindres - de la présente invention est de fournir une composition aux propriétés stabilisantes élevées qui permette d'éliminer le réchauffement des solutions et d'éliminer leur agitation ainsi que le contrôle permanent du taux de peroxydes contenu dans les bains.Another objective - and not least - of the present invention is to provide a composition with high stabilizing properties which makes it possible to eliminate the heating of the solutions and to eliminate their agitation as well as the permanent control of the level of peroxides contained in the baths. .

L'invention concerne une composition stabilisante des peroxydes inorganiques destinée aux bains de traitement de surface des pièces métalliques selon laquelle elle comprend au moins un agent activant sélectionné parmi les benzotriazoles, l'imidazole et les carboxyimidazoles ou leurs dérivés.The invention relates to a stabilizing composition for inorganic peroxides intended for baths for the surface treatment of metal parts, according to which it comprises at least one activating agent selected from benzotriazoles, imidazole and carboxyimidazoles or their derivatives.

D'autres caractéristiques et avantages supplémentaires de l'invention découleront en majeure partie de la description d'une forme d'exécution préférée mais non exclusive de la composition à propriétés stabilisantes élevées et ce, en particulier pour les peroxydes inorganiques utilisés dans le cadre d'applications industrielles.Other additional characteristics and advantages of the invention will derive mainly from the description of a preferred but non-exclusive embodiment of the composition with high stabilizing properties, in particular for the inorganic peroxides used in the context of 'applications industrial.

Par peroxydes inorganiques, on entend désigner le peroxyde d'hydrogène, les peracides inorganiques et leurs sels, plus particulièrement les acides perboriques, perphosphoriques et persulfuriques et leurs sels de métaux alcalins ou alcalinoterreux, ainsi que les peroxydes de métaux alcalins et alcalinoterreux tels que les peroxydes de sodium, de calcium et de magnésium. De préférence, on utilise le peroxyde d'hydrogène ou les peracides inorganiques. De très bons résultats ont été obtenus avec le peroxyde d'hydrogène.The term “inorganic peroxides” is intended to denote hydrogen peroxide, inorganic peracids and their salts, more particularly perboric, perphosphoric and persulfuric acids and their alkali or alkaline earth metal salts, as well as peroxides of alkali and alkaline earth metals such as sodium, calcium and magnesium peroxides. Preferably, hydrogen peroxide or inorganic peracids are used. Very good results have been obtained with hydrogen peroxide.

Par traitement de surface des pièces métalliques, on entend désigner le traitement des pièces métalliques à l'aide d'un bain comprenant un ou plusieurs composés acides et un ou plusieurs composés oxydants notamment en vue de les décaper par l'enlèvement des oxydes couvrant leur surface, ou encore de les passiver ou d'améliorer le fini de surface plus particulièrement de les polir et/ou d'effectuer un traitement de brillantage.The term “surface treatment of metal parts” is intended to denote the treatment of metal parts using a bath comprising one or more acidic compounds and one or more oxidizing compounds, in particular with a view to stripping them by removing the oxides covering their surface, or passivate them or improve the surface finish, more particularly to polish them and / or perform a polishing treatment.

Selon l'invention, la composition est destinée à être incorporée aux bains de traitement de surface des pièces métalliques. Elle ne contient généralement pas elle-même de peroxyde, celui-ci étant ajouté au bain de traitement de façon indépendante.According to the invention, the composition is intended to be incorporated into the surface treatment baths of metal parts. It generally does not itself contain peroxide, which is added to the treatment bath independently.

Comme on le sait, l'action stabilisante des peroxydes et leur capacité à accélérer la désoxydation dépendent de la composition des bains dans lesquels le mélange standard traditionnel nitrique-fluorhydrique est remplacé, en ce qui concerne la partie nitrique, par de l'eau oxygénée dans la proportion molaire H₂O₂-HNO₃ de 1/2 à 2/1 mais de préférence de 1/1, alors que la partie acide de l'acide nitrique est remplacée par de l'acide sulfurique dans la proportion molaire HNO₃-H₂SO₄ de 1/2 à 2,5/1, mais de préférence de 1/1,3.As is known, the stabilizing action of peroxides and their capacity to accelerate deoxidation depend on the composition of the baths in which the traditional standard nitric-hydrofluoric mixture is replaced, as regards the nitric part, by oxygenated water in the H₂O₂-HNO₃ molar proportion of 1/2 to 2/1 but preferably 1/1, while the acid part of the nitric acid is replaced by sulfuric acid in the HNO₃-H₂SO₄ molar proportion of 1 / 2 to 2.5 / 1, but preferably 1 / 1.3.

La partie acide en ce qui concerne l'acide sulfurique peut être remplacée, en tout ou en partie, par des acides inorganiques de type phosphorique, sulfamique ou autre, dans la mesure où ils n'entraînent pas une interaction négative avec le stabilisant de l'eau oxygénée ou du peroxyde.The acid part with regard to sulfuric acid may be replaced, in whole or in part, by inorganic acids of phosphoric, sulfamic or other type, insofar as they do not cause a negative interaction with the stabilizer of the hydrogen peroxide or peroxide.

La partie fluorhydrique peut quant à elle comprendre au moins un composé choisi parmi les acides fluorés ou les sels fluorés et le pourcentage est maintenu dans les valeurs standard habituelles que l'on connaît.The hydrofluoric part can for its part comprise at least one compound chosen from fluorinated acids or fluorinated salts and the percentage is maintained within the usual standard values that are known.

Le bain ainsi obtenu requiert la présence d'un agent stabilisant du peroxyde dans la proportion de 1/100 à 1/1, mais de préférence de 1/30 à 1/2, en fonction du peroxyde utilisé.The bath thus obtained requires the presence of a peroxide stabilizing agent in the proportion of 1/100 to 1/1, but preferably from 1/30 to 1/2, depending on the peroxide used.

La longévité des solutions est comparable ou supérieure à celle d'un bain traditionnel équivalent, du type de ceux que l'on connaît habituellement.The longevity of the solutions is comparable or superior to that of an equivalent traditional bath, of the type of those which one usually knows.

L'agent stabilisant utilisé pour les bains de ces compositions et qui constitue l'objet de la présente invention, peut comprendre outre l'agent activant au moins, un autre composé choisi parmi les agents stabilisants, les composés solvants de l'agent stabilisant, les catalyseurs d'oxydation, les agents de mouillage capables de résister dans un environnement acide oxydant, éventuellement des phosphates ou des phosphonates à titre de co-adjuvants de précipitation et de désactivation des métaux dissous, et enfin, des acides inorganiques et/ou organiques en tant qu'uniformisateurs du produit.The stabilizing agent used for the baths of these compositions and which constitutes the object of the present invention, can comprise, in addition to the activating agent at least, another compound chosen from stabilizing agents, the solvent compounds of the stabilizing agent, oxidation catalysts, wetting agents capable of resisting in an oxidizing acid environment, optionally phosphates or phosphonates as co-adjuvants for precipitation and deactivation of dissolved metals, and finally, inorganic and / or organic acids as product standardizers.

Selon une variante de l'invention, la composition comprend en outre au moins un agent stabilisant.According to a variant of the invention, the composition also comprises at least one stabilizing agent.

Pour ce qui est de l'agent stabilisant en particulier, il peut comporter un ou plusieurs anneaux aromatiques ou cycliques ou une ou plusieurs chaînes aliphatiques. Il peut en outre contenir au moins un groupe choisi parmi les groupes hydroxyliques, carboxyliques, sulfonates et phosphates. Par groupes sulfonates et phosphates, on entend désigner ici aussi bien les groupes sulfoniques et phosphoriques que leurs sels. Il peut aussi contenir au moins un groupe choisi parmi les esters, éthers, diènes, azoles, mercapto-azoles ou des combinaisons de ceux-ci.As regards the stabilizing agent in particular, it may comprise one or more aromatic or cyclic rings or one or more aliphatic chains. It can also contain at least one group chosen from hydroxyl, carboxylic, sulfonate and phosphate groups. The term “sulfonate and phosphate groups” is intended to denote here both the sulfonic and phosphoric groups and their salts. It can also contain at least one group chosen from esters, ethers, dienes, azoles, mercapto-azoles or combinations thereof.

Selon l'invention, l'agent stabilisant peut comprendre au moins un composé sélectionné parmi les composés aromatiques ou alicycliques mono ou polycycliques et les composés aliphatiques substitués par au moins un groupe choisi parmi les groupes hydroxyles, carboxyles, sulfonates, phosphates, esters, éthers, diènes, azoles et mercapto-azoles. De bons résultats ont été obtenus avec les composés substitués par des groupes sulfonates (ou sulfoniques) et phosphates (ou phosphoriques) ou leurs mélanges. L'acide p-toluène sulfonique convient bien.According to the invention, the stabilizing agent may comprise at least one compound selected from mono or polycyclic aromatic or alicyclic compounds and aliphatic compounds substituted by at least one group chosen from the groups hydroxyls, carboxyls, sulfonates, phosphates, esters, ethers, dienes, azoles and mercapto-azoles. Good results have been obtained with compounds substituted by sulfonate (or sulfonic) groups and phosphates (or phosphoric) groups or mixtures thereof. P-Toluene sulfonic acid is well suited.

En combinaison avec l'agent activant, les compositions selon l'invention peuvent comprendre au moins un composé solvant de l'agent stabilisant.In combination with the activating agent, the compositions according to the invention can comprise at least one solvent compound for the stabilizing agent.

Le composé solvant appelé aussi partie dissolvante de l'agent stabilisant décrit ci-avant peut comprendre des alcools, des glycols, des polyéthers, du diméthylformamide, de la N-méthylpyrrolidone, des cétones, des polyglycols, des esters, des condensats à bas poids moléculaire ou des groupes organiques caractérisés par une solubilité raisonnable dans l'eau, résistant dans un environnement acide et disposant d'un bon pouvoir dissolvant des composants organiques utilisés comme agents stabilisants et présentant une solubilité nulle ou peu élevée dans l'eau ou dans les acides inorganiques aux concentrations d'utilisation.The solvent compound also called dissolving part of the stabilizing agent described above can include alcohols, glycols, polyethers, dimethylformamide, N-methylpyrrolidone, ketones, polyglycols, esters, low-weight condensates molecular or organic groups characterized by a reasonable solubility in water, resistant in an acidic environment and having a good dissolving power of the organic components used as stabilizing agents and having zero or low solubility in water or in inorganic acids at use concentrations.

Le composé solvant de l'agent stabilisant comprend de préférence au moins un composé sélectionné parmi les alcools, les glycols et les polyglycols.The solvent compound of the stabilizing agent preferably comprises at least one compound selected from alcohols, glycols and polyglycols.

Selon une autre variante de l'invention, le composé solvant peut aussi contenir, en mélange avec lesdits alcools, glycols et/ou polyglycols au moins un adjuvant choisi parmi le diméthylformamide et la N-méthylpyrrolidone.According to another variant of the invention, the solvent compound can also contain, in admixture with said alcohols, glycols and / or polyglycols at least one adjuvant chosen from dimethylformamide and N-methylpyrrolidone.

Le composé solvant peut comprendre des polyesters, des cétones, des esters, des condensats à faible poids moléculaire ou des groupes organiques présentant une bonne solubilité dans l'eau et résistant dans un milieu acide.The solvent compound can include polyesters, ketones, esters, low molecular weight condensates or organic groups with good water solubility and resistance in an acidic medium.

L'agent activant, qui peut en outre également être utilisé indépendamment des agents stabilisants ou composés solvants mentionnés ci-avant comprend des composants aminés cycliques, aromatiques, dérivés des imidazoles et/ou des carboxy-imidazoles, et/ou d'amines aliphatiques.The activating agent, which can also also be used independently of the stabilizing agents or solvent compounds mentioned above, comprises cyclic, aromatic amine components, derivatives of imidazoles and / or carboxy-imidazoles, and / or aliphatic amines.

Les compositions selon l'invention peuvent aussi contenir au moins un composé choisi parmi les catalyseurs d'oxydation constitués de métaux et les agents mouillants résistant dans un milieu acide oxydant.The compositions according to the invention can also contain at minus one compound chosen from oxidation catalysts made up of metals and wetting agents resistant in an oxidizing acid medium.

Les catalyseurs d'oxydation peuvent comprendre au moins un métal appartenant au premier, au deuxième, au troisième ou au quatrième groupe. Ceux-ci sont présents en pourcentage variant de 2 à 20.000 ppm et de préférence de 10 à 3.000 ppm.The oxidation catalysts can comprise at least one metal belonging to the first, second, third or fourth group. These are present in a percentage varying from 2 to 20,000 ppm and preferably from 10 to 3,000 ppm.

Par groupe, on entend désigner un groupe qui correspond à une famille représentée dans une même colonne du tableau périodique des éléments.By group is meant a group which corresponds to a family represented in the same column of the periodic table of the elements.

Les métaux du groupe 3 se sont révélés intéressants et de bons résultats ont été obtenus avec l'aluminium.The metals of group 3 have proved to be interesting and good results have been obtained with aluminum.

Selon une autre variante de l'invention, la composition peut aussi comprendre au moins un agent mouillant stable en milieu acide oxydant, c'est-à-dire un agent capable de modifier la tension superficielle à l'interface solide/liquide afin d'améliorer le mouillage des pièces métalliques par le bain de traitement. Il convient que cet agent mouillant soit sélectionné parmi ceux qui sont chimiquement inertes en présence d'une solution aqueuse acide et oxydante et, en particulier, les solutions aqueuses acides de peroxydes.According to another variant of the invention, the composition may also comprise at least one wetting agent stable in oxidizing acid medium, that is to say an agent capable of modifying the surface tension at the solid / liquid interface in order to improve the wetting of metal parts by the treatment bath. This wetting agent should be selected from those which are chemically inert in the presence of an acidic and oxidizing aqueous solution and, in particular, acidic aqueous solutions of peroxides.

Les agents mouillants capables de résister dans un environnement acide oxydant, sont constitués de condensats non ioniques, anioniques, amphotères ou cationiques ou de dérivés fluorés, ou d'un mélange de ceux-ci. De bons résultats ont été obtenus avec des tensioactifs anioniques fluorés et des condensats d'éthylène glycol avec des alkylphénols ainsi que leurs mélanges.Wetting agents capable of resisting in an oxidizing acid environment, consist of nonionic, anionic, amphoteric or cationic condensates or fluorinated derivatives, or a mixture of these. Good results have been obtained with fluorinated anionic surfactants and ethylene glycol condensates with alkylphenols and their mixtures.

Le bain de décapage constitué de la sorte et présentant l'agent stabilisant décrit ci-avant peut opérer à partir d'un pH égal à 2,5 et jusqu'à un pH de 0,0, mais d'ordinaire, il opère à un pH inférieur à 1,3.The pickling bath constituted in this way and having the stabilizing agent described above can operate from a pH equal to 2.5 and up to a pH of 0.0, but usually it operates at a pH below 1.3.

De préférence, le bain de décapage peut opérer à des valeurs de pH égales ou inférieures à 0,3.Preferably, the pickling bath can operate at pH values equal to or less than 0.3.

La présence éventuelle de concentrations de métaux supérieures à 10.000 ppm ne réduit pas considérablement la stabilité du système décapant dans la mesure où la composition stabilisante renferme des inhibiteurs qui désactivent l'action de décomposition des ions métalliques.The possible presence of metal concentrations higher than 10,000 ppm does not considerably reduce the stability of the pickling system insofar as the stabilizing composition contains inhibitors which deactivate the decomposition action of metal ions.

Par contre, d'autres composants de la composition stabilisante réduisent le potentiel d'oxydation des sous-oxydes de fer/ nickel/chrome et catalysent leur oxydation, favorisant de la sorte la transformation en oxydes solubles.On the other hand, other components of the stabilizing composition reduce the oxidation potential of the iron / nickel / chromium sub-oxides and catalyze their oxidation, thereby promoting the transformation into soluble oxides.

La présence dans un bain de décapage de la composition stabilisante, objet de la présente invention, permet de réaliser le décapage dans des délais et à des températures extrêmement compétitifs par rapport aux bains actuellement utilisés.The presence in a pickling bath of the stabilizing composition which is the subject of the present invention makes it possible to carry out pickling in a time and at extremely competitive temperatures compared to the baths currently used.

Selon une autre variante de la composition selon l'invention, on peut aussi lui incorporer des adjuvants de précipitation et, partant, de désactivation des métaux dissous provenant de la dissolution des oxydes ou de la partie superficielle de la pièce métallique sous l'action du bain de traitement. De tels adjuvants peuvent être des sels solubles inorganiques ou organiques dont l'anion se combine avec le cation du ou des métaux dissous dans le bain pour former un sel dont le produit de solubilité est très faible dans les conditions régnant dans le bain, par exemple inférieur à 10⁻⁵ ion gramme.According to another variant of the composition according to the invention, it is also possible to incorporate precipitation additives and, consequently, deactivation of the dissolved metals originating from the dissolution of the oxides or from the surface part of the metal part under the action of the treatment bath. Such adjuvants can be soluble inorganic or organic salts whose anion combines with the cation of the metal or metals dissolved in the bath to form a salt whose solubility product is very low under the conditions prevailing in the bath, for example less than 10⁻⁵ gram ion.

La composition peut en outre comprendre au moins un composé choisi parmi les phosphates et les phosphonates en tant que co-adjuvants de précipitation et de désactivation des métaux dissous et les acides inorganiques et organiques comme agents d'égalisation du traitement. Ces derniers servent à l'uniformisation du produit.The composition can also comprise at least one compound chosen from phosphates and phosphonates as co-adjuvants for precipitation and deactivation of dissolved metals and inorganic and organic acids as treatment-leveling agents. These are used to standardize the product.

Les co-adjuvants de précipitation peuvent être choisis parmi les phosphates et phosphonates de tous types. Les pyrophosphates conviennent bien.The precipitation co-adjuvants can be chosen from phosphates and phosphonates of all types. Pyrophosphates are well suited.

Enfin, à titre d'agents permettant l'obtention d'un résultat uniforme sur toute la surface de la pièce métallique à traiter, on peut aussi ajouter au bain un ou plusieurs acides inorganiques et/ou organiques. Les acides organiques sont préférés. Des exemples de tels acides organiques sont l'acide picrique et l'acide citrique.Finally, as agents allowing a uniform result to be obtained over the entire surface of the metal part to be treated, it is also possible to add to the bath one or more inorganic and / or organic acids. Organic acids are preferred. Examples of such organic acids are picric acid and citric acid.

En réalité, l'action décapante obtenue par le biais de l'utilisation de la composition présentant des propriétés stabilisantes élevées et qui fait l'objet de la présente invention, ne nécessite normalement aucune agitation des bains ou des éléments qui y sont immergés.In reality, the stripping action obtained through the use of the composition having high stabilizing properties and which is the subject of the present invention normally does not require any agitation of the baths or of the elements which are immersed therein.

Quoi qu'il en soit, il est possible d'utiliser de manière très valable, en lieu et place de l'agitation mécanique et dans le même but que celle-ci, des ultrasons qui sont normalement associés au bain décapant ou, de préférence, au cours des phases de rinçage, ce qui permet d'obtenir une synergie du résultat.Anyway, it is possible to use very validly, instead of and for the same purpose of mechanical agitation, ultrasound which is normally associated with the pickling bath or, preferably , during the rinsing phases, which makes it possible to obtain a synergy of the result.

L'utilisation des ultrasons permet en fait de réduire considérablement la durée du décapage et ce, jusqu'à 1/6 du temps qui aurait été nécessaire en l'absence de l'utilisation des ultrasons.The use of ultrasound in fact makes it possible to considerably reduce the duration of pickling and this, up to 1/6 of the time which would have been necessary in the absence of the use of ultrasound.

L'invention concerne donc également des procédés de traitement de surface métalliques plus particulièrement de surfaces d'aciers inoxydables en présence des compositions stabilisantes décrites ci-avant au moyen d'au moins un peroxyde inorganique à pH acide. Ce traitement est ensuite suivi d'au moins un rinçage. Au cours d'au moins une des phases de traitement ou de rinçage, l'agitation du bain peut être obtenue à l'aide d'ultrasons.The invention therefore therefore also relates to methods for treating metallic surfaces, more particularly stainless steel surfaces in the presence of the stabilizing compositions described above using at least one inorganic peroxide at acid pH. This treatment is then followed by at least one rinsing. During at least one of the treatment or rinsing phases, agitation of the bath can be obtained using ultrasound.

Dans le procédé selon l'invention, on peut mettre en oeuvre des doses variables des divers composés actifs et notamment d'acide, de peroxydes inorganiques et de composition stabilisante selon l'invention. On peut ainsi mettre de 0,1 à 5 moles et de préférence de 0,5 à 3 moles de composé peroxydé par litre de solution. La quantité d'acide est ajoutée pour maintenir le pH aux valeurs souhaitées. Parmi les acides que l'on peut utiliser à cette fin, on peut signaler l'acide sulfurique qui convient particulièrement bien. Il peut être utilisé en association avec des fluorures et par exemple avec l'acide fluorhydrique dans des rapports variables. Dans ce cas, les rapports pondéraux acide sulfurique/acide fluorhydrique ne dépassent généralement pas 500 et, le plus souvent, pas 100. De même ces rapports ne sont généralement pas inférieurs à 0,1 et, le plus souvent, pas inférieurs à 1.In the process according to the invention, variable doses of the various active compounds and in particular of acid, of inorganic peroxides and of stabilizing composition according to the invention can be used. It is thus possible to use 0.1 to 5 moles and preferably 0.5 to 3 moles of peroxidized compound per liter of solution. The amount of acid is added to maintain the pH at the desired values. Among the acids which can be used for this purpose, mention may be made of sulfuric acid which is particularly suitable. It can be used in combination with fluorides and for example with hydrofluoric acid in variable ratios. In this case, the sulfuric acid / hydrofluoric acid weight ratios generally do not exceed 500 and, more often than not, 100. Likewise these ratios are generally not less than 0.1 and, most often, not less than 1.

L'invention concerne aussi l'utilisation de la composition décrite ci-avant pour l'élaboration d'un bain de décapage, de passivage, de brillantage et/ou de polissage des métaux.The invention also relates to the use of the composition described above for the preparation of a pickling, passivating, polishing and / or polishing bath for metals.

A titre d'illustration, on rapporte l'exemple suivant d'une composition type d'un bain décapant pour aciers tels que les aciers austénitiques. Cet exemple n'a nullement pour but de limiter la portée de l'invention.By way of illustration, the following example is reported of a typical composition of a pickling bath for steels such as austenitic steels. This example is in no way intended to limit the scope of the invention.

ExempleExample

   Une composition type comprend :A typical composition includes: acide sulfurique à 98 %98% sulfuric acid de 4 à 300 g/lfrom 4 to 300 g / l peroxyde d'hydrogène à 100 %100% hydrogen peroxide de 0,2 à 100 g/lfrom 0.2 to 100 g / l acide fluorhydriquehydrofluoric acid de 0,5 à 10 g/lfrom 0.5 to 10 g / l composition stabilisantestabilizing composition de 0,2 à 30 g/lfrom 0.2 to 30 g / l où la composition stabilisante type est constitué de :where the standard stabilizing composition consists of: acide p-toluène sulfoniquep-toluene sulfonic acid 1010 N-méthylpyrrolidoneN-methylpyrrolidone 2222 éthylèneglycolethylene glycol 55 benzotriazole + imidazole (environ 50 % - 50 %)benzotriazole + imidazole (about 50% - 50%) 33 aluminium +++aluminum +++ 33 tensioactif anionique fluoréfluorinated anionic surfactant 0,50.5 (FC R 95 : marque déposée de la société 3M)(FC R 95: registered trademark of 3M company) condensat d'oxyde d'éthylène et d'octylphénolethylene oxide and octylphenol condensate 55 ion pyrophosphatepyrophosphate ion 44 acide sulfuriquesulfuric acid 1010 acide citriquecitric acid 22 eauwater complément à 100complement to 100

Des tests comparatifs ont été réalisés sur des tubes recuits en acier AISI 304 et traités de la manière suivante :

  • 1 - mélange classique contenant 180 g/l d'acide nitrique et 30 g/l d'acide fluorhydrique ainsi que des agents mouillants (3 g/l). Cette solution a opéré durant 45 minutes à 30 °C.
  • 2 - mélange contenant 180 g/l d'acide sulfurique, 40 g/l de H₂O₂ et 30 g/l d'acide fluorhydrique. Mêmes conditions que dans le cas 1.
  • 3 - mélange semblable au mélange 2, mais adjonction de la composition stabilisante type à raison de 5 g/l et préparée comme indiqué.
  • 4 - mélange semblable au mélange 2 avec adjonction de la composition stabilisante à raison de 1 g/l.
  • 5 - mélange semblable au mélange 2 avec adjonction de la composition stabilisante à raison de 10 g/l. Les résultats obtenus sont les suivants :
Comparative tests were carried out on annealed AISI 304 steel tubes and treated as follows:
  • 1 - conventional mixture containing 180 g / l of nitric acid and 30 g / l of hydrofluoric acid as well as wetting agents (3 g / l). This solution operated for 45 minutes at 30 ° C.
  • 2 - mixture containing 180 g / l of sulfuric acid, 40 g / l of H₂O₂ and 30 g / l of hydrofluoric acid. Same conditions as in case 1.
  • 3 - mixture similar to mixture 2, but addition of the standard stabilizing composition at a rate of 5 g / l and prepared as indicated.
  • 4 - mixture similar to mixture 2 with the addition of the stabilizing composition at a rate of 1 g / l.
  • 5 - mixture similar to mixture 2 with the addition of the stabilizing composition at a rate of 10 g / l. The results obtained are as follows:

DécapagePickling

Test 1 =Test 1 =
par comparaisonby comparing
Test 2 =Test 2 =
incompletincomplete
Test 3 =Test 3 =
résultat semblable au test 1 après une durée de 35 minutesresult similar to test 1 after 35 minutes
Test 4 =Test 4 =
résultat semblable au test 1 après une durée de 45 minutesresult similar to test 1 after 45 minutes
Test 5 =Test 5 =
résultat semblable au test 1 après une durée de 30 minutesresult similar to test 1 after 30 minutes

Perte de poids en H₂O₂

Test 2 =
24 heures après le test, il reste 8 g de H₂O₂ par l.
Test 3 =
24 heures après le test, il reste 32 g de H₂O₂ par l.
Test 4 =
24 heures après le test, il reste 28 g de H₂O₂ par l.
Test 5 =
24 heures après le test, il reste 33 g de H₂O₂ par l.
Weight loss in H₂O₂
Test 2 =
24 hours after the test, 8 g of H₂O₂ per l remain.
Test 3 =
24 hours after the test, 32 g of H₂O₂ per l remain.
Test 4 =
24 hours after the test, 28 g of H₂O₂ per l remain.
Test 5 =
24 hours after the test, 33 g of H₂O₂ per l remain.

Le même test répété après 96 heures présente les valeurs suivantes :

Test 2 =
2 g de H₂O₂ par l.
Test 3 =
28 g de H₂O₂ par l.
Test 4 =
20 g de H₂O₂ par l.
Test 5 =
31 g de H₂O₂ par l.
The same test repeated after 96 hours has the following values:
Test 2 =
2 g of H₂O₂ per l.
Test 3 =
28 g H₂O₂ per l.
Test 4 =
20 g of H₂O₂ per l.
Test 5 =
31 g of H₂O₂ per l.

On a ensuite effectué des tests de stabilité en incorporant dans le mélange, constitué de 180 g/l d'acide sulfurique, de 40 g/l de H₂O₂ et de 30 g/l d'acide fluorhydrique, une quantité de 8 g/l d'acier AISI 304 et en rapportant ensuite la teneur en H₂O₂ aux valeurs initiales.Stability tests were then carried out by incorporating into the mixture, consisting of 180 g / l of sulfuric acid, 40 g / l of H₂O₂ and 30 g / l of hydrofluoric acid, an amount of 8 g / l of AISI 304 steel and then relating the H₂O₂ content to the initial values.

On a ajouté à la solution obtenue la composition stabilisante type dans les quantités suivantes :

Test 6 =
1 g/l
Test 7 =
5 g/l
Test 8 =
10 g/l
The standard stabilizing composition was added to the solution obtained in the following amounts:
Test 6 =
1 g / l
Test 7 =
5 g / l
Test 8 =
10 g / l

Ces différentes solutions ont été maintenues à une température de 25 °C et à 50 °C durant 48 heures. On a obtenu ce faisant les résultats suivants :

Test 6 =
34 g/l et 24 g/l de H₂O₂
Test 7 =
37 g/l et 32 g/l de H₂O₂
Test 8 =
38 g/l et 35 g/l de H₂O₂
These various solutions were maintained at a temperature of 25 ° C and at 50 ° C for 48 hours. The following results were obtained:
Test 6 =
34 g / l and 24 g / l H₂O₂
Test 7 =
37 g / l and 32 g / l H₂O₂
Test 8 =
38 g / l and 35 g / l of H₂O₂

Il ressort des tests effectués que la composition stabilisante type permet d'éviter la décomposition du peroxyde d'hydrogène et ce, même à chaud.It appears from the tests carried out that the standard stabilizing composition makes it possible to avoid the decomposition of hydrogen peroxide, even when hot.

On a pu constater dans la pratique que la composition de l'invention présentant des propriétés stabilisantes élevées et plus particulièrement dans le cas des peroxydes inorganiques utilisés dans le cadre d'applications industrielles, offrait de nombreux avantages en tout genre.It has been found in practice that the composition of the invention having high stabilizing properties and more particularly in the case of inorganic peroxides used in the context of industrial applications, offers many advantages of all kinds.

Par exemple, les températures d'utilisation des bains de décapage se révèlent être égales ou réellement inférieures aux températures qui sont celles des bains à base d'acide nitrique et fluorhydrique et donc, fortement polluants.For example, the temperatures of use of pickling baths appear to be equal to or really lower than the temperatures which are those of baths based on nitric and hydrofluoric acid and therefore, highly polluting.

En utilisant dans un bain la composition présentant d'importantes propriétés stabilisantes, objet de la présente invention, on ne constate aucune émission de vapeurs nitreuses, et l'émission d'acides, par exemple de fluorures, est quant à elle extrêmement réduite.By using in a bath the composition having important stabilizing properties, object of the present invention, there is no emission of nitrous vapors, and the emission of acids, for example fluorides, is itself extremely reduced.

Il est possible d'utiliser, dans le cas des bains qui font appel à la composition nouvelle et objet de la présente invention, les mêmes équipements que ceux qui sont utilisés dans le cas de mélanges nitrique-fluorhydriques, et ce, sans qu'il soit toutefois nécessaire d'opérer d'importantes modifications de ces installations.It is possible to use, in the case of baths which make use of the new composition and subject of the present invention, the same equipment as that which is used in the case of nitric-hydrofluoric mixtures, and this, without it however, major modifications to these facilities are required.

On obtient entre autres également l'élimination des corrosions intergranulaires et le procédé peut être adapté aux différents types d'aciers inoxydables tels que par exemple les aciers de la série AISI 400 (dont le décapage s'opère généralement assez difficilement avec les systèmes traditionnels) ou encore, les aciers de la série AISI 300. Il est bien entendu que les compositions selon l'invention conviennent également bien pour le traitement d'autres types d'aciers inoxydables.Intergranular corrosion is also eliminated, among other things, and the process can be adapted to different types of stainless steels such as, for example, steels from the AISI 400 series (pickling is generally difficult with traditional systems). or still, the steels of the AISI 300 series. It is understood that the compositions according to the invention are also well suited for the treatment of other types of stainless steels.

Il importe également de rappeler que l'utilisation de la composition stabilisante décrite ci-dessus permet notamment de réduire de manière considérable la consommation de peroxyde inorganique plus particulièrement de peroxyde d'hydrogène et ce, tout en permettant des temps de décapage égaux ou réellement inférieurs, jusqu'à 50 % même, par rapport aux temps de décapage nécessaires dans le cas des bains traditionnels.It is also important to remember that the use of the stabilizing composition described above makes it possible in particular to considerably reduce the consumption of inorganic peroxide, more particularly hydrogen peroxide, while allowing equal or really lower pickling times. , even up to 50%, compared to the stripping times required in the case of traditional baths.

Outre ces différents avantages, on constate encore que le résultat donne une surface de couleur blanc-argenté, sans trace de poussière.In addition to these various advantages, it can also be seen that the result gives a silvery-white surface, without any trace of dust.

Dans le cas où l'on souhaiterait en outre accélérer par la suite le processus de décapage, il est possible - comme nous l'avions expliqué et comme nous le revendiquons - d'utiliser également un système à ultrasons au cours des phases de décapage et/ou de rinçage, et ce, de manière à réduire considérablement les délais de ces deux opérations.In the event that it is further desired to speed up the pickling process further, it is possible - as we have explained and as we claim - to also use an ultrasonic system during the pickling phases and / or rinsing, so as to considerably reduce the times for these two operations.

L'invention mise au point est susceptible de nombreuses modifications et variantes, qui rentrent toutes dans le cercle du présent concept inventif. Tous les détails peuvent en outre être remplacés par des éléments techniquement équivalents.The invention developed is susceptible to numerous modifications and variants, which all fall within the circle of the present inventive concept. All details may also be replaced by technically equivalent elements.

Claims (13)

  1. Stabilizing composition for inorganic peroxides intended for baths for the surface treatment of metal components, characterized in that it comprises at least one activating agent selected from benzotriazoles, imidazole and carboxyimidazoles or their derivatives.
  2. Composition according to Claim 1, characterized in that it additionally comprises at least one stabilizing agent.
  3. Composition according to Claim 2, characterized in that it additionally comprises at least one solvent compound of the stabilizing agent.
  4. Composition according to any one of Claims 1 to 3, characterized in that it additionally comprises an oxidation catalyst comprising at least one metal belonging to groups I to IV of the Periodic Table.
  5. Composition according to any one of Claims 1 to 4, characterized in that it additionally contains at least one wetting agent which is stable in acidic oxidizing medium.
  6. Composition according to Claim 2, characterized in that the stabilizing agent comprises at least one compound selected from mono- or polycyclic alicyclic or aromatic compounds and aliphatic compounds substituted by at least one group chosen from hydroxyl, carboxyl, sulphonate, phosphate, ester, ether, diene, azole and mercaptoazole groups.
  7. Composition according to any one of Claims 3 to 6, characterized in that the solvent compound comprises at least one compound selected from alcohols, glycols and polyglycols.
  8. Composition according to Claim 7, characterized in that the solvent compound additionally comprises at least one adjuvant chosen from dimethylformamide and N-methylpyrrolidone.
  9. Composition according to any one of Claims 1 to 8, characterized in that it additionally comprises at least one compound chosen from phosphates and phosphonates as coadjuvants for the precipitation and deactivation of the dissolved metals and inorganic and organic acids as agents for equalization of the treatment.
  10. Use of the composition according to any one of Claims 1 to 9 for producing a bath for pickling, polishing or burnishing metals.
  11. Process for the treatment of metal surfaces, characterized in that they are subjected to a treatment with at least one inorganic peroxide at an acid pH in the presence of the compositions according to any one of Claims 1 to 9.
  12. Process according to Claim 11, characterized in that at least one rinsing is carried out after the treatment.
  13. Process according to either of Claims 11 and 12, characterized in that, during at least one of the treatment or rinsing stages, agitation of the bath is obtained using ultrasound.
EP92922319A 1991-10-25 1992-10-23 Composition for stabilizing inorganic peroxide solutions Expired - Lifetime EP0609342B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
ITMI91284 1991-10-25
ITMI912845A IT1251431B (en) 1991-10-25 1991-10-25 COMPOUND WITH HIGH STABILIZING CHARACTERISTICS, PARTICULARLY FOR INORGANIC PEROXIDES USED IN INDUSTRIAL APPLICATIONS
PCT/EP1992/002442 WO1993008317A1 (en) 1991-10-25 1992-10-23 Composition for stabilizing inorganic peroxide solutions

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EP0609342A1 EP0609342A1 (en) 1994-08-10
EP0609342B1 true EP0609342B1 (en) 1996-05-08

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EP (1) EP0609342B1 (en)
JP (1) JPH07500378A (en)
KR (1) KR100249061B1 (en)
BR (1) BR9206668A (en)
CA (1) CA2121691A1 (en)
DE (1) DE69210622T2 (en)
ES (1) ES2089573T3 (en)
FI (1) FI100727B (en)
IT (1) IT1251431B (en)
WO (1) WO1993008317A1 (en)

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FI941893A (en) 1994-06-01
WO1993008317A1 (en) 1993-04-29
KR100249061B1 (en) 2000-04-01
CA2121691A1 (en) 1993-04-29
ITMI912845A0 (en) 1991-10-25
ES2089573T3 (en) 1996-10-01
EP0609342A1 (en) 1994-08-10
JPH07500378A (en) 1995-01-12
IT1251431B (en) 1995-05-09
BR9206668A (en) 1995-10-24
DE69210622T2 (en) 1996-11-28
US5538152A (en) 1996-07-23
ITMI912845A1 (en) 1993-04-25
FI941893A0 (en) 1994-04-22
FI100727B (en) 1998-02-13

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