EP0871802B1 - Procede permettant d'eliminer l'acide degage pendant le trempage electrophoretique cathodique - Google Patents

Procede permettant d'eliminer l'acide degage pendant le trempage electrophoretique cathodique Download PDF

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Publication number
EP0871802B1
EP0871802B1 EP96930151A EP96930151A EP0871802B1 EP 0871802 B1 EP0871802 B1 EP 0871802B1 EP 96930151 A EP96930151 A EP 96930151A EP 96930151 A EP96930151 A EP 96930151A EP 0871802 B1 EP0871802 B1 EP 0871802B1
Authority
EP
European Patent Office
Prior art keywords
acid
anode
oxidation
membrane
bath
Prior art date
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.)
Expired - Lifetime
Application number
EP96930151A
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German (de)
English (en)
Other versions
EP0871802A1 (fr
Inventor
Klaus Arlt
Udo Heil
Karl-Heinz Grosse-Brinkhaus
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.)
BASF Coatings GmbH
Original Assignee
BASF Coatings GmbH
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Filing date
Publication date
Application filed by BASF Coatings GmbH filed Critical BASF Coatings GmbH
Publication of EP0871802A1 publication Critical patent/EP0871802A1/fr
Application granted granted Critical
Publication of EP0871802B1 publication Critical patent/EP0871802B1/fr
Anticipated expiration legal-status Critical
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/22—Servicing or operating apparatus or multistep processes
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D21/00—Processes for servicing or operating cells for electrolytic coating
    • C25D21/16—Regeneration of process solutions
    • C25D21/18—Regeneration of process solutions of electrolytes

Definitions

  • the present invention relates to a method for removing the the cathodic electrocoating during the deposition of the Lacquer film released acid from the electro-immersion bath.
  • the anolyte cycle first assumes that the anode is replaced by a Diaphragm or membrane separated from the rest of the electrodeposition bath is.
  • This membrane is usually an anion exchange membrane only a flow of anions, i.e. in the present case acid residues, in Direction towards the anode. Paint binders and pigments held back against it.
  • electro-immersion baths usually contain an ultrafiltration circuit. This draws bath liquid and directly this leads to an ultrafiltration to accumulate in the bath Solvent and other low molecular components of the paint cut off. Paint binders and pigments are used restrained and returned to the bathroom.
  • the literature e.g. "color + lacquer", 2/1981, pp. 94ff).
  • DE-44 09 270 also proposes the anodic oxidation of the acid used before.
  • acid i.e. over 90%, formic acid used.
  • Platinum is the theoretically possible anode material or platinum-plated stainless steel electrodes, platinized titanium electrodes, platinum-plated graphite electrodes, ruthenium-doped stainless steel electrodes or mixed oxide-doped electrodes made of stainless steel, titanium or graphite called.
  • Electrodes that can be used in electrochemical processes are known from German Patent 15 71 721 electrodes, which u.a. used as an anode to carry out chlor-alkali electrolysis become.
  • German Offenlegungsschrift 34 23 605 composite electrodes made of electrically conductive plastic and partly in it injected catalytic particles (carrier particles with applied Catalyst) and processes for their preparation. You can as an oxygen anode, for example in the electrolytic extraction of Metals from aqueous solutions are used. As another Areas of application are electrodialysis and electrocoating called.
  • European patent 0 296167 (equivalent to US Pat. No. 4,879,013 ) likewise describes the use of comparable electrodes (so-called “dimensionally stable anodes DSA") in cathodic electrocoating. These are neither dissolved nor destroyed during the electrophoretic coating process under the conditions of the electrodeposition process there, ie with regard to the paint formulation, current density, pH value and the decomposing influence of chlorine. With regard to the removal of accumulating components, in particular acid, in the electrocoating bath, the use of an anolyte circuit is preferred, which is periodically rinsed .
  • DSA dimensionally stable anodes
  • Electrodes for oxidative degradation were also tested and used in the field of wastewater treatment. It was found in particular that electrodes with a coating of tin oxide (SnO 2 ) have a high efficiency in the electrochemical degradation of organic substances. These electrodes were tested in particular in comparison to conventional electrodes, for example the DSA electrodes mentioned above (Stucki, Kötz, Carcer, Suter: “Electrochemical waste water treatment using high overvoltage anodes, Part II: Anode performance and applications", Journal of Applied Electrochemistry 21 (1991), 99-104; Comninellis: “Traitment des eaux residuaires par intens electrochimique", gwa 11/92, 792-797; Comninellis: “Electrochemical treatment of waste water containing phenol", Electrochemical Engineering and the Environment 92, Symposium Series No. 127, 189-201).
  • the present invention has now set itself the task of Process for removing cathodic Electrocoating during the deposition of the paint film to provide released acid, which is the number of necessary rinsing processes via the anolyte circuit to remove Acid and possible degradation products of the acid reduced or the whole without the anolyte cycle.
  • the electrodes used according to the invention are more chemically stable than the medium. It is also possible according to the invention to use acids other than formic acid, namely acetic acid, lactic acid and / or dimethylolpropionic acid . However, due to their lower theoretical maximum value, these are generally less favorable for electrochemical degradability. For example, only around 35% of lactic acid can be broken down electrochemically.
  • the anolyte circuit can even be completely dispensed with, ie the electrodes according to the invention can be inserted directly into the electrodeposition bath and the anode and cathode compartments no longer have to be separated from one another by a membrane.
  • additional methods for reducing the acid content are used according to the invention.
  • membrane processes known per se These preferably start with the ultrafiltrate, because the higher molecular paint components are no longer present here. Examples of suitable membrane processes are processes using dialysis, osmosis, reverse osmosis, electrodialysis or a further ultrafiltration.
  • Electrocoating baths which contain cationic groups as binders containing synthetic resins. It is preferably protonated reaction products from epoxy groups Synthetic resins and amines. These are preferably Formic acid, acetic acid, lactic acid and dimethylolpropionic acid. All the use of formic acid is preferred. The acids mentioned are oxidized to water and carbon dioxide at the anode.
  • the substrate of the electrodes according to the invention can be made of metal or conductive plastic exist. It is preferably the Metals around titanium, tantalum, niobium or an alloy of these metals. In for example, an alloy of titanium and 1 to 15% by weight Molybdenum. Titanium is particularly preferred as the substrate.
  • the layer applied to the anodes used according to the invention from ruthenium, iridium or tin oxide or a mixture of these Oxides preferably have a layer thickness of 0.01 to 10 ⁇ m. On a particularly preferred range is 0.1-7 ⁇ m.
  • the invention further relates to the use of a with a layer of tin oxide coated anode for removal of cathodic electrocoating Acid released during the deposition of the paint film by means of Oxidation.
  • the acid is preferably formic acid, Acetic acid, lactic acid and / or dimethylolpropionic acid.
  • a titanium electrode coated with iridium oxide serves as the anode (Dimensions 10 x 10 cm) directly in the electrocoating material immersed.
  • steel sheets (dimensions approx. 10 x 20 cm) are coated automatically at 28 ° C with 280 V for 2 min.
  • the layer thickness is approx. 20 ⁇ m.
  • the sheets will n dipped after the coating in the ultrafiltrate to adherent resist material due to rinse and thus the immersion bath.
  • the meq acid analyzes show the development of the acidity in Dependence on the compensation rate.

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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)
  • Prevention Of Electric Corrosion (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Claims (10)

  1. Procédé d'élimination de l'acide libéré pendant le dépôt de la pellicule de peinture lors du trempage phorétique cathodique,
    l'acide étant décomposé par oxydation sur une anode, qui est revêtue d'une couche d'oxyde de ruthénium, d'oxyde d'iridium ou d'oxyde d'étain ou d'un mélange de ces oxydes,
    caractérisé en ce que de l'acide formique, de l'acide acétique, de l'acide lactique et/ou de l'acide diméthylolpropionique sont oxydés sur l'anode.
  2. Procédé suivant la revendication 1, caractérisé en ce que l'oxydation a lieu dans un circuit d'anolyte.
  3. Procédé suivant la revendication 1, caractérisé en ce que l'anode et la cathode ne sont pas séparées l'une de l'autre par une membrane dans le bain d'immersion électrique, et qu'outre l'oxydation anodique, une séparation supplémentaire d'acide a lieu à l'aide d'un procédé par membrane.
  4. Procédé suivant la revendication 3, caractérisé en ce qu'un circuit d'ultrafiltration est présent dans le bain de trempage électrique et le procédé par membrane est réalisé avec l'ultrafiltrat.
  5. Procédé suivant l'une des revendications 3 ou 4, caractérisé en ce que le procédé par membrane est une dialyse, une électrodialyse, une osmose, une osmose inverse ou une deuxième ultrafiltration.
  6. Procédé suivant l'une des revendications 1 à 5, caractérisé en ce que les anodes sont utilisées dans des bains de trempage électrique, qui contiennent comme liant des résines synthétiques présentant des groupements cationiques.
  7. Procédé suivant l'une des revendications 1 à 6, caractérisé en ce que les résines synthétiques sont des produits de transformation protonés à partir de résines synthétiques contenant des groupements époxydes et d'amines.
  8. Procédé suivant l'une des revendications 1 à 7, caractérisé en ce qu'on utilise des anodes qui contiennent comme substrat un métal ou une matière plastique conductrice, le titane, le tantale, le niobium ou un alliage de ces métaux comme par exemple du titane avec 1-15% en poids de molybdène étant de préférence utilisés.
  9. Utilisation d'une anode revêtue d'une couche d'oxyde d'étain pour l'élimination de l'acide libéré pendant le dépôt de la pellicule de peinture lors du trempage phorétique cathodique électrique au moyen d'une oxydation.
  10. Utilisation de l'anode suivant la revendication 9, pour l'oxydation de l'acide formique, de l'acide acétique, de l'acide lactique et/ou de l'acide diméthylolpropionique.
EP96930151A 1995-09-18 1996-09-02 Procede permettant d'eliminer l'acide degage pendant le trempage electrophoretique cathodique Expired - Lifetime EP0871802B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19534534A DE19534534A1 (de) 1995-09-18 1995-09-18 Verfahren zur Entfernung der bei der kathodischen Elektrotauchlackierung freigesetzten Säure
DE19534534 1995-09-18
PCT/EP1996/003845 WO1997011211A1 (fr) 1995-09-18 1996-09-02 Procede permettant d'eliminer l'acide degage pendant le trempage electrophoretique cathodique

Publications (2)

Publication Number Publication Date
EP0871802A1 EP0871802A1 (fr) 1998-10-21
EP0871802B1 true EP0871802B1 (fr) 2000-01-05

Family

ID=7772455

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96930151A Expired - Lifetime EP0871802B1 (fr) 1995-09-18 1996-09-02 Procede permettant d'eliminer l'acide degage pendant le trempage electrophoretique cathodique

Country Status (6)

Country Link
US (2) US6398944B1 (fr)
EP (1) EP0871802B1 (fr)
AT (1) ATE188518T1 (fr)
DE (2) DE19534534A1 (fr)
ES (1) ES2143778T3 (fr)
WO (1) WO1997011211A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19938886C1 (de) * 1999-08-17 2001-02-01 Dupont Automotive Coatings Gmb Reinigungsmittel und Verfahren zur Reinigung von Ultrafiltrationsmembranen in Elektrotauchlackierungsanlagen
DE10235117B3 (de) * 2002-08-01 2004-02-12 EISENMANN Maschinenbau KG (Komplementär: Eisenmann-Stiftung) Anlage zur kataphoretischen Tauchlackierung von Gegenständen
US20170096742A1 (en) * 2015-10-02 2017-04-06 Waste Hub Electrochemical processes for acid whey treatment and reuse

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL128866C (fr) 1965-05-12
GB1195871A (en) 1967-02-10 1970-06-24 Chemnor Ag Improvements in or relating to the Manufacture of Electrodes.
US3682814A (en) * 1970-09-25 1972-08-08 Scm Corp Cathodic electrocoating process
DE3423605A1 (de) 1984-06-27 1986-01-09 W.C. Heraeus Gmbh, 6450 Hanau Verbundelektrode, verfahren zu ihrer herstellung und ihre anwendung
US4879013A (en) 1986-03-03 1989-11-07 Ppg Industries, Inc. Method of cationic electrodeposition using dissolution resistant anodes
AU580475B2 (en) 1986-03-03 1989-01-12 Ppg Industries, Inc. Cationic electrodeposition using dissolution resistant anodes
DE3642164A1 (de) 1986-12-10 1988-06-23 Basf Ag Verfahren zum entfernen von saeure aus kathodischen elektrotauchlackier-baedern mittels elektrodialyse
DE4409270C1 (de) 1994-03-18 1995-03-30 Herberts Gmbh Verfahren zur abwasserfreien kataphoretischen Tauchlackierung

Also Published As

Publication number Publication date
DE19534534A1 (de) 1997-03-20
WO1997011211A1 (fr) 1997-03-27
ATE188518T1 (de) 2000-01-15
ES2143778T3 (es) 2000-05-16
US6398944B1 (en) 2002-06-04
US20020060155A1 (en) 2002-05-23
DE59604138D1 (de) 2000-02-10
EP0871802A1 (fr) 1998-10-21

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