EP0587525A1 - Procédé pour le prétraitement de pièces en métal ou d'alliages - Google Patents

Procédé pour le prétraitement de pièces en métal ou d'alliages Download PDF

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Publication number
EP0587525A1
EP0587525A1 EP93810511A EP93810511A EP0587525A1 EP 0587525 A1 EP0587525 A1 EP 0587525A1 EP 93810511 A EP93810511 A EP 93810511A EP 93810511 A EP93810511 A EP 93810511A EP 0587525 A1 EP0587525 A1 EP 0587525A1
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EP
European Patent Office
Prior art keywords
acid
electrolyte
metal
current
weight
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP93810511A
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German (de)
English (en)
Inventor
Oldrich Stanek
Keizo Matsuo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3A Composites International AG
Original Assignee
Alusuisse Lonza Services Ltd
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Publication of EP0587525A1 publication Critical patent/EP0587525A1/fr
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
    • C25D11/10—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing organic acids

Definitions

  • the invention relates to a process for the pretreatment of materials made of metals or metal alloys before painting, gluing or plastic lamination by electrochemical oxidation with alternating current or three-phase current in an electrolyte bath.
  • a further improvement in paint adhesion is achieved with the method described in DE-OS 33 25 802, according to which the oxidation of an aluminum strip with 3-phase alternating current (three-phase current), one phase of which is rectified, is carried out in such a way that the strip has three electrodes happened one after the other. At least one of these electrodes, preferably the middle one, is connected to the rectified phase, the others to the two remaining three-phase phases.
  • the disadvantage of the known oxidation processes in an acidic environment is the relatively high concentration of sulfuric acid of 15-20% by weight and the process temperature of at least 80 ° C., falling below this results in a significant reduction in adhesion.
  • oxidation in basic electrolytes e.g. Hydroxides, carbonates and phosphates
  • concentrations below 1% by weight and temperatures below 50 ° C can be used to produce oxide layers with good adhesion.
  • these basic processes require exact adherence to the pH value, the temperature and the substance concentration, which is associated with major problems when the content of dissolved aluminum increases. Even small deviations from the target value can jump from good to poor adhesion to the oxide layers.
  • the inventor has set himself the task of creating a process for the pretreatment of materials made of metals or metal alloys before painting, gluing or plastic lamination by electrochemical oxidation in an electrolyte bath, which has the same or better adhesion guaranteed and that it is less pH dependent. Furthermore, non-toxic components should be used, which do not pollute the environment with decomposition gases or wastewater contaminants and which do not leave any harmful substances in the conversion layer formed.
  • the object is achieved according to the invention in that the metals or metal alloys are heated in an aqueous electrolyte heated to 15-95 ° C. and adjusted to a pH of -1 to 15, the 0.01-20% by weight of at least one metal compound reacting organic compound of the general formula (a) R-COOH, where R has the meaning of -H; an alkyl group with 1 to 8 carbon atoms; an alkyl group with 1 to 3 carbon atoms which is substituted with cycloalkyl with 5 to 10 carbon atoms; a cycloalkyl group with 5 to 10 carbon atoms; has an alkenyl group with 2 to 8 C atoms or an aryl group with 6 to 12 C atoms; and or of the general formula (b) R1-SO3H, where R 'is an alkyl group having 1 to 8 carbon atoms; has an alkyl group with 1 to 3 C atoms which is substituted by cycloalkyl with 5 to 10 C atoms, or an
  • R and in the compounds of the formula (b) R 'can have the meaning of an alkyl group having 1 to 8 carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl or R-ethyl-hexyl.
  • cycloaklyl groups with 5 to 10 carbon atoms for R in compounds of the formula (a) are e.g. Cyclopentyl, cyclohexyl, 2- or 4-methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, t-butylcyclohexyl or cycloctyl.
  • alkyl groups with 1 to 3 carbon atoms which are substituted by a cycloalkyl group with 5 to 10 carbon atoms, such as those mentioned in compounds of the formula (a) and for R 'in compounds of the formula (b) Methyl, ethyl, propyl or isopropyl groups with, for example, cyclopentyl, cyclohexyl, 2- or 4-methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, t-butylcyclohexyl or cycloctyl.
  • alkenyl groups with 2 to 8 carbon atoms for R in compounds of the formula (a) are e.g. Vinyl, propenyl, allyl, butenyl, methylallyl or hexenyl.
  • aryl groups with 6 to 12 carbon atoms for R or R 'in compounds of the formula (a) or. (b) are phenyl or substituted phenyl such as methylphenyl, dimethylphenyl or trimethylphenyl.
  • R '' in compounds of formula (c) can be an alkyl group such as methyl, ethyl, propyl or isopropyl.
  • R "" - CH CH-COOH
  • R '''- CH CH-CH2-COOH
  • R '''- CH CH-CH2-COOH
  • R '''- C6H4-SO3H where R '''has the meaning of -H, methyl or ethyl, preferably of -H.
  • Preferred compounds are allylic acid, acetic acid, propionic acid and particularly preferably acrylic acid.
  • Preferred compounds are the oligomers of acrylic acid, the oligomers of methacrylic acid, co-oligomers of acrylic acid and methacrylic acid, co-oligomers of acrylic acid and / or methacrylic acid with 3-butenic acid, maleic acid or fumaric acid, or mixtures of the compounds mentioned.
  • the aqueous electrolyte can also contain an inorganic acid and / or an alkali metal or alkaline earth metal hydroxide.
  • the inorganic acid can be, for example, sulfuric acid, phosphoric acid, hydrochloric acid or be nitric acid.
  • the amount of acid can be up to 10% by weight, expediently from 0.01 to 10% by weight, calculated as 100% acid, based on the electrolyte.
  • Sulfuric acid is preferred, used in an amount of, for example, 0.1 to 2.2% by weight, advantageously 0.4 to 2% by weight and preferably 0.5% by weight, calculated as 100% acid. based on the electrolyte.
  • the alkali or alkaline earth metal hydroxide can e.g. LiOH, NaOH, KOH, Ca (OH) 2, Mg (OH) 2, etc.; NaOH, KOH and Ca (OH) 2 are preferred.
  • the amount of alkali metal hydroxides and alkaline earth metal hydroxides can be up to 10% by weight, expediently from 0.01 to 10% by weight, based on the electrolyte.
  • Aqueous electrolytes containing 1 to 7% by weight and in particular 5% by weight of acrylic acid and 0.1 to 2% by weight and in particular 0.5% by weight of H2SO4 are preferred.
  • the materials can e.g. Plates, sheets, strips, thin strips, foils, fabrics, knitted fabrics, felts or fibers made of metals or metal alloys or which are plated or coated with metals or metal alloys.
  • metals e.g. Ferrous or non-ferrous metals, respectively. their alloys e.g. Iron, steel, copper, zinc, galvanized iron, tin, bronze, non-ferrous metals, aluminum etc. can be used. Aluminum and aluminum alloys are preferred. Examples of aluminum alloys are AlFeSi, AlMn0.5Mg0.5 and AlMg2.5.
  • the organic compounds reacting with metals or metal alloys preferably in a concentration of 0.1 to 20% by weight, in particular 1 to 10% by weight.
  • electrolytes containing 5% by weight of the organic compound reacting with metals or metal alloys oxide layers with an optimal paint adhesion of, for example, more than 30 N / 15 mm (peeling force value) can be produced, in particular if the required conductivity and the pH value with sulfuric acid can be set.
  • peeling force values of, for example, 40-85 N / 15 mm are achieved.
  • the peeling force values relate, for example, to epoxy-phenol paints.
  • the temperature of the electrolyte is kept at 15 to 95 ° C. and preferably at a value between 40 and 65 ° C. and in particular at 50 ° C. to 60 ° C.
  • the complexing agents are saturated with the metal dissolved during the electrochemical oxidation, which is associated with a reduction in the oxidation ability of the electrolyte.
  • a higher concentration of the complexing agent down to 10% by weight delays this saturation accordingly. This is associated with a reduction in the pH value and the conductivity of the electrolyte.
  • the initial pH value, the conductivity and thus also the oxidation ability of the electrolyte can be kept constant.
  • the concentration of the metal in the electrolyte has reached a certain limit, it begins to precipitate out as metal hydroxide, which can be filtered off. This largely stabilizes the bath composition, so that only the amount of electrolyte carried out with the belt has to be replaced and the conductance may need to be corrected.
  • a stabilizer preferably a polysaccharide, such as e.g. Dextran or starch, preferably in an amount of approximately 0.05% by weight, can be used.
  • the materials are advantageously passed through the electrolyte at such a speed that the current density between 3 and 100 A / dm2, expediently 6-25 A / dm2 and advantageously 12 A / dm2.
  • the electrolysis mass is dimensioned such that the oxidation time, ie the throughput time of the materials in the electrolyte in the region of the electrodes or the electrochemical reaction time is 0.5 to 15 sec, preferably 2 to 7 sec, and in particular 3 to 5 sec.
  • the voltage can be 20 V, for example.
  • the pretreated materials are e.g. 1 to 4 times, preferably 3 or 4 times, rinsed with water.
  • the rinsed materials can be left to dry at ambient conditions or can be dried at 90 to 140 ° C for about 20 to 30 seconds.
  • alternating current used for the oxidation is not critical per se; it can have a sinusoidal, rectangular or triangular shape or be present as a direct current superimposed with alternating or pulsed current. It also has no significant influence on the oxide layer formation, whether the oxidation takes place with two-phase alternating current or with three-phase current.
  • the power supply to the electrodes and z. B. the tape or film do not matter. There are practically the same result if, for. B. the tape or the film, contacted directly, forms an electrode, or if the current is connected to two or more separate electrodes, under which the tape coupled over the electrolyte represents a current-carrying connections, as in DE-OS 33 25 802 is described.
  • oxide layers produced with direct current have poorer paint adhesion, and pretreatment with direct current is also less and less advantageous for gluing or plastic lamination.
  • the pretreated materials can e.g. painted, laminated or pasted. It was found that painting one day after a pretreatment according to the invention and painting a month after the pretreatment according to the invention were applied to each sample gave equally good results and the pretreated surface did not change in 4 weeks.
  • the electrolysis cell shown in FIG. 1 comprises an oxidation container 10 with an electrolyte 12.
  • a metal strip, and here an aluminum strip 16 is unwound from a roll 14, guided horizontally through the electrolyte 12 via deflection rollers 18 in the region of two electrodes 20a, 20b and onto it the other side of the cell wound on a roll 22.
  • the electrodes 20a, 20b are embedded in a holder 24 made of electrically insulating, electrolyte-resistant material such that only the electrode surfaces facing the aluminum strip, which form the working surface, are not insulated.
  • the vertical walls 26 of the holder 24 directed onto the aluminum strip 16 protrude the electrodes 20a, 20b and are guided up to the vicinity of the aluminum strip 16.
  • the single-phase transformer 30 connected to the alternating current source 28 supplies the electrodes 20a, 20b via the conductors 32 with two-phase sinusoidal alternating current with a frequency of 50-60 Hz.
  • a simple transformer with a mains connection is the cheapest solution.
  • Laboratory tests have found that other types of alternating current, e.g. Rectangular, triangular, pulse currents from lower or higher frequencies do not bring any significant improvement in the quality of the oxide layer.
  • FIG. 2 shows a variant according to which the conductor 32a is connected directly to the aluminum strip 16.
  • the secondary circuit is closed via the electrolyte (not shown), the single electrode 20 and the conductor 32b.
  • the symbolic arrangement for the three-phase oxidation shown in FIG. 3 comprises a three-phase transformer 34, of which only the secondary windings 36a, 36b and 36c are shown. These secondary windings are connected to the electrodes 20a, 20b and 20c via the conductors 32a, 32b and 32c.
  • FIG. 4 differs from FIG. 3 only in that a diode 38 is installed in the middle conductor 32b, this phase is therefore rectified.
  • the aluminum strip 16 can be connected directly to the secondary power source via a conductor 40.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Paints Or Removers (AREA)
EP93810511A 1992-08-05 1993-07-16 Procédé pour le prétraitement de pièces en métal ou d'alliages Ceased EP0587525A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH2459/92 1992-08-05
CH2459/92A CH685300A5 (de) 1992-08-05 1992-08-05 Verfahren zur Vorbehandlung von Werkstoffen aus Metallen oder Metallegierungen.

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EP0587525A1 true EP0587525A1 (fr) 1994-03-16

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EP93810511A Ceased EP0587525A1 (fr) 1992-08-05 1993-07-16 Procédé pour le prétraitement de pièces en métal ou d'alliages

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CH (1) CH685300A5 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102011167A (zh) * 2010-09-26 2011-04-13 广西贺州市桂东电子科技有限责任公司 一种电子铝箔初段化成液添加剂及其添加方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2404683A1 (fr) * 1977-09-30 1979-04-27 Shokosha Kk Traitement electrolytique d'articles en aluminium ou en alliages d'aluminium pour y former une pellicule brillante
GB2071153A (en) * 1980-02-27 1981-09-16 Citizen Watch Co Ltd Method for manufacturing a bicoloured polyhedral body of aluminium
EP0048909A1 (fr) * 1980-09-26 1982-04-07 Hoechst Celanese Corporation Procédé pour l'oxydation anodique d'aluminium et son utilisation comme support d'une plaque d'impression
EP0184756A2 (fr) * 1984-12-10 1986-06-18 Hoechst Celanese Corporation Electrolyte pour le traitement électrochimique des plaques métalliques et procédé de fabrication de plaques métalliques anodisées, de préférence pour l'application comme supports de plaques d'impression
CH660379A5 (en) * 1984-03-16 1987-04-15 Alusuisse Process for pretreating strips or foils made of aluminium or aluminium alloys
EP0318403A1 (fr) * 1987-11-23 1989-05-31 Pechiney Rhenalu Procédé d'anodisation en continu de bandes en aluminium ou en un de ses alliages destinées à être revêtues d'un produit organique
EP0354132A1 (fr) * 1988-07-06 1990-02-07 Aluminium Pechiney Procédé d'émaillage en continu de fils en alliage d'aluminium destinés à la confection de bobinages électriques

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2404683A1 (fr) * 1977-09-30 1979-04-27 Shokosha Kk Traitement electrolytique d'articles en aluminium ou en alliages d'aluminium pour y former une pellicule brillante
GB2071153A (en) * 1980-02-27 1981-09-16 Citizen Watch Co Ltd Method for manufacturing a bicoloured polyhedral body of aluminium
EP0048909A1 (fr) * 1980-09-26 1982-04-07 Hoechst Celanese Corporation Procédé pour l'oxydation anodique d'aluminium et son utilisation comme support d'une plaque d'impression
EP0050216A2 (fr) * 1980-09-26 1982-04-28 American Hoechst Corporation Procédé pour l'oxydation anodique d'aluminium et son utilisation comme support pour planches d'imprimerie
CH660379A5 (en) * 1984-03-16 1987-04-15 Alusuisse Process for pretreating strips or foils made of aluminium or aluminium alloys
EP0184756A2 (fr) * 1984-12-10 1986-06-18 Hoechst Celanese Corporation Electrolyte pour le traitement électrochimique des plaques métalliques et procédé de fabrication de plaques métalliques anodisées, de préférence pour l'application comme supports de plaques d'impression
EP0318403A1 (fr) * 1987-11-23 1989-05-31 Pechiney Rhenalu Procédé d'anodisation en continu de bandes en aluminium ou en un de ses alliages destinées à être revêtues d'un produit organique
EP0354132A1 (fr) * 1988-07-06 1990-02-07 Aluminium Pechiney Procédé d'émaillage en continu de fils en alliage d'aluminium destinés à la confection de bobinages électriques

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102011167A (zh) * 2010-09-26 2011-04-13 广西贺州市桂东电子科技有限责任公司 一种电子铝箔初段化成液添加剂及其添加方法

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Publication number Publication date
CH685300A5 (de) 1995-05-31

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