WO1991014807A1 - Process for sewage-free operation of baths in installations for cathodic electrophoretic enamelling - Google Patents

Process for sewage-free operation of baths in installations for cathodic electrophoretic enamelling Download PDF

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Publication number
WO1991014807A1
WO1991014807A1 PCT/AT1991/000047 AT9100047W WO9114807A1 WO 1991014807 A1 WO1991014807 A1 WO 1991014807A1 AT 9100047 W AT9100047 W AT 9100047W WO 9114807 A1 WO9114807 A1 WO 9114807A1
Authority
WO
WIPO (PCT)
Prior art keywords
ultrafiltrate
installations
binder
lead
baths
Prior art date
Application number
PCT/AT1991/000047
Other languages
German (de)
French (fr)
Inventor
Willibald Paar
Franz Holzer
Günther Wulff
Original Assignee
Vianova Kunstharz Aktiengesellschaft
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Vianova Kunstharz Aktiengesellschaft filed Critical Vianova Kunstharz Aktiengesellschaft
Publication of WO1991014807A1 publication Critical patent/WO1991014807A1/en

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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
    • C25D13/24—Regeneration of process liquids

Definitions

  • the invention relates to a process for wastewater-free bath management in systems for cathodic electrocoating (KTL systems) using the ultrafiltrate obtained for the dispersion of the binder and / or lacquer components used in the systems.
  • the dip coating is delivered in the form of at least two components. These are a relatively concentrated pigment paste and an aqueous dispersion of the main binder, which has a solids content of between 30 and 40% by weight. After the two components have been mixed, this varnish is used to add to the used immersion varnish in the pool, depending on the requirements. Since the lacquer is deposited on the substrate with a solids content of over 90% by weight during electrocoating, the dispersion medium is continuously enriched in the immersion tank, ie. H. of water and small proportions of organic auxiliary solvents. Additional water is fed to the plunge pool by rinsing the workpieces with fresh water.
  • ultrafiltration systems are used, by means of which part of the aqueous medium can be removed from the bath material.
  • This ultrafiltrate which in addition to water and auxiliary solvents can also contain dissolved portions of pigments and / or low molecular weight binders and / or additives, is used in practice for first rinses of the painted workpieces are used and then mostly returned to the plunge pool - this method is, for example, in DE-AS-20 57 438, in DE-OS-22 29 677 and in DE-PS-39 01 938 - or used to dilute delivered, concentrated lacquers, as is also known from DE-AS-29 14 550, or the ultrafiltrate must be disposed of in a suitable manner.
  • Paints according to DE-AS-29 14 550 contain only organic solvents in the form of the diluent. In order to ensure the handling during the production and transportation of such varnishes, considerable amounts of these solvents are necessary, which accumulate in the bath during the continuous operation of a KTL system and ultimately in the ultrafiltrate.
  • the present invention accordingly relates to a process for wastewater-free bath management in systems for cathodic electrocoating, which is characterized in that the entire operation of the systems is used to disperse the binder and / or paint components used resulting ultrafiltrate used, with the proviso that if the ultrafiltrate is used for lead-free paint formulations, the lead salts which may be present are removed beforehand.
  • the ultrafiltrate is advantageously used for the dispersion of binder and / or paint components which have an at least similar chemical structure to the binder as the paint material from which the ultrafiltrate originates.
  • the products required for the ongoing operation of the systems to supplement can be manufactured in this way.
  • the process according to the invention achieves both an ecological and an economic advantage.
  • the lead content of the ultrafiltrate is taken into account in the formulation of the paint, so that there is no accumulation of lead over a long period of time in the bathroom.
  • the content of water-soluble, low molecular weight resin and additives should not be more than 0.5% by weight, since an enrichment of these substances causes defects on the paint surface or a reduction the adhesion of the KTL primer to the substrate or to the subsequent layer of lacquer.
  • Reuse By recycling 2 m 3 of the pretreated ultrafiltrate for the dispersion and dilution of the main binder, 4 t of dispersion are produced. The remaining 0.1 t of water are used in the form of deionized water.

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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)

Abstract

In a process for sewage-free operation of baths in installations for cathodic electrophoretic enamelling, the binder and/or enamel constituents are dispersed using ultrafiltrate produced during operation of the installations, provided that any lead salts are removed from the ultrafiltrate before use in order to obtain lead-free formulations of lacque.

Description

Verfahren zur abwasserf eien Badführung bei Anlagen zur kathodisehen Elektrotauchlackierung.Process for wastewater-free bath management in systems for cathodic electrocoating.
Die Erfindung betrifft ein Verfahren zur abwasserfreien Badführung bei Anlagen zur kathodischen Elektrotauch¬ lackierung (KTL-Anlagen) unter Verwendung des anfallen¬ den Ultrafiltrats für die Dispergierung der in den An¬ lagen eingesetzten Bindemittel- und/oder Lackkomponen¬ ten.The invention relates to a process for wastewater-free bath management in systems for cathodic electrocoating (KTL systems) using the ultrafiltrate obtained for the dispersion of the binder and / or lacquer components used in the systems.
Entsprechend dem aktuellen Stand der Technik wird bei KTL-Anlagen in vielen Fällen der Tauchlack in Form von zumindest zwei Komponenten angeliefert. Es sind dies eine relativ konzentrierte Pigmentpaste und eine wäßri- ge Dispersion des Hauptbindemittels, die einen Festkör¬ pergehalt zwischen 30 und 40 Gew.-% aufweist. Nach dem Mischen der beiden Komponenten wird mit diesem Lack, nach Maßgabe des jeweiligen Bedarfs, der verbrauchte Tauchlack im Becken ergänzt. Da bei der Elektrobe- Schichtung der Lack mit einem Festkörpergehalt von über 90 Gew.-% auf das Substrat abgeschieden wird, erfolgt im Tauchbecken eine laufende Anreicherung des Disper- giermediums, d. h. von Wasser und geringen Anteilen von organischen Hilfslösemitteln. Zusätzliches Wasser wird durch die Endspülung der Werkstücke mit Frischwasser dem Tauchbecken zugeführt.According to the current state of the art, in many cases the dip coating is delivered in the form of at least two components. These are a relatively concentrated pigment paste and an aqueous dispersion of the main binder, which has a solids content of between 30 and 40% by weight. After the two components have been mixed, this varnish is used to add to the used immersion varnish in the pool, depending on the requirements. Since the lacquer is deposited on the substrate with a solids content of over 90% by weight during electrocoating, the dispersion medium is continuously enriched in the immersion tank, ie. H. of water and small proportions of organic auxiliary solvents. Additional water is fed to the plunge pool by rinsing the workpieces with fresh water.
Da der Badverlust durch Verdunstung oder Austrag nicht ausreicht, den Wasserüberschuß auszugleichen, werden Ultrafiltrationsanlagen verwendet, mittels welcher dem Badmaterial ein Teil des wäßrigen Mediums entzogen wer¬ den kann. Dieses Ultrafiltrat , welches neben Wasser und Hilfslösemitteln noch gelöste Anteile von Pigmenten und/oder niedrigmolekularen Bindemitteln und/oder Additiven enthalten kann, wird in der Praxis für die ersten Spülungen der lackierten Werkstücke benützt und anschließend im überwiegenden Anteil wieder in das Tauchbecken zurückgeführt - dieses Verfahren ist bei¬ spielsweise in der DE-AS-20 57 438, in der DE-OS-22 29 677 und in der DE-PS-39 01 938 beschrieben - oder zum Verdünnen von angelieferten, konzentrierten Lacken ver¬ wendet, wie es auch aus der DE-AS-29 14 550 bekannt ist, oder das Ultrafiltrat muß in geeigneter Weise ent¬ sorgt werden.Since the bath loss due to evaporation or discharge is not sufficient to compensate for the excess water, ultrafiltration systems are used, by means of which part of the aqueous medium can be removed from the bath material. This ultrafiltrate, which in addition to water and auxiliary solvents can also contain dissolved portions of pigments and / or low molecular weight binders and / or additives, is used in practice for first rinses of the painted workpieces are used and then mostly returned to the plunge pool - this method is, for example, in DE-AS-20 57 438, in DE-OS-22 29 677 and in DE-PS-39 01 938 - or used to dilute delivered, concentrated lacquers, as is also known from DE-AS-29 14 550, or the ultrafiltrate must be disposed of in a suitable manner.
Lacke gemäß der DE-AS-29 14 550 enthalten in der Lie¬ ferform als Verdünnungsmedium ausschließlich organische Lösemittel. Um die Handhabung während der Herstellung und des Transports derartiger Lacke zu gewährleisten, sind erhebliche Mengen dieser Lösemittel notwendig, die sich beim Dauerbetrieb einer KTL-Anlage im Bad und schließlich im Ultrafiltrat anreichern.Paints according to DE-AS-29 14 550 contain only organic solvents in the form of the diluent. In order to ensure the handling during the production and transportation of such varnishes, considerable amounts of these solvents are necessary, which accumulate in the bath during the continuous operation of a KTL system and ultimately in the ultrafiltrate.
Der Einsatz lösemittelarmer Tauchlacke ist aus ökologi- sehen Gründen vorteilhaft und wird in vielen Ländern bereits vom Gesetzgeber gefordert. Als Beispiel seien die VOC (volatile organic composition) regulations in den USA angeführt.The use of low-solvent dip coatings is advantageous for ecological reasons and is already required by law in many countries. One example is the VOC (volatile organic composition) regulations in the USA.
Es wurde nun gefunden, daß die bei KTL-Anlagen als Ul¬ trafiltrat anfallenden Abwassermengen nutzbringend als Dispergiermedium bei der Bindemittel- bzw. Lackherstel¬ lung verwendet werden können.It has now been found that the amounts of wastewater obtained in the KTL systems as ultrafiltrate can be used as a dispersing medium in the manufacture of binders or paints.
Die vorliegende Erfindung betrifft demgemäß ein Verfah¬ ren zur abwasserfreien Badführung bei Anlagen zur ka¬ thodischen Elektrotauchlackierung, welches dadurch ge¬ kennzeichnet ist, daß man zur Dispergierung der einge¬ setzten Bindemittel- und/oder Lackkomponenten das ge- samte, beim Betrieb der Anlagen anfallende Ultrafiltrat verwendet, mit der Maßgabe, daß bei Verwendung des Ul- trafiltrats für bleifreie Lackformulierungen die gege¬ benenfalls vorhandenen Bleisalze vorher entfernt wer¬ den.The present invention accordingly relates to a process for wastewater-free bath management in systems for cathodic electrocoating, which is characterized in that the entire operation of the systems is used to disperse the binder and / or paint components used resulting ultrafiltrate used, with the proviso that if the ultrafiltrate is used for lead-free paint formulations, the lead salts which may be present are removed beforehand.
Vorteilhafterweise wird das Ultrafiltrat zur Disper- gierung von Bindemittel- und/oder Lackkomponenten ver¬ verwendet, die einen zumindest ähnlichen chemischen Aufbau der Bindemittel aufweisen, wie das Lackmaterial, dem das Ultrafiltrat entstammt. Insbesonders können in dieser Weise die für den laufenden Betrieb der Anlagen zur Ergänzung benötigten Produkte gefertigt werden.The ultrafiltrate is advantageously used for the dispersion of binder and / or paint components which have an at least similar chemical structure to the binder as the paint material from which the ultrafiltrate originates. In particular, the products required for the ongoing operation of the systems to supplement can be manufactured in this way.
Da in der Automobilindustrie, dem wichtigsten Anwender des kathodischen Elektrotauchverfahrens, bei einer An¬ lage pro Arbeitstag mehrere Kubikmeter an Ultrafiltrat zur Entsorgung anfallen können, wird durch das erfin¬ dungsgemäße Verfahren sowohl ein ökologischer wie auch ein wirtschaftlicher Vorteil erzielt.Since in the automobile industry, the most important user of the cathodic electro-immersion process, several cubic meters of ultrafiltrate can be generated for disposal per working day, the process according to the invention achieves both an ecological and an economic advantage.
Bei Verwendung von bleisalzhältigem Ultrafiltrat für die Herstellung von Dispersionen zur Formulierung blei¬ freier Lacke ist es notwendig, die Bleisalze durch li¬ teraturbekannte Verfahren, wie durch Fällung oder durch Ionenaustauscher, aus dem Ultrafiltrat zu entfernen.When using lead salt-containing ultrafiltrate for the production of dispersions for the formulation of lead-free lacquers, it is necessary to remove the lead salts from the ultrafiltrate by methods known from literature, such as by precipitation or by ion exchangers.
Bei der Formulierung bleihaltiger Lacke wird der Blei¬ gehalt des Ultrafiltrats in der Rezeptur des Lackes mitberücksichtigt, sodaß im Badbetrieb auch über länge- re Zeit keine Anreicherung von Blei auftritt.In the formulation of lead-containing paints, the lead content of the ultrafiltrate is taken into account in the formulation of the paint, so that there is no accumulation of lead over a long period of time in the bathroom.
Der Gehalt an wasserlöslichen, niedrigmolekularen Harz¬ anteilen und Zusatzstoffen soll nicht mehr als 0,5 Gew.-% betragen, da eine Anreicherung dieser Stoffe Defekte an der Lackoberfläche oder eine Verringerung der Haftung der KTL-Grundierung zum Substrat bzw. zur folgenden Lackschicht auslösen kann.The content of water-soluble, low molecular weight resin and additives should not be more than 0.5% by weight, since an enrichment of these substances causes defects on the paint surface or a reduction the adhesion of the KTL primer to the substrate or to the subsequent layer of lacquer.
Eventuell vorhandene organische HilfsLösemittel werden bei der Lackfertigung berücksichtigt." Any organic auxiliary solvents that may be present are taken into account in paint production. "
Im folgenden wird mittels einer Materialbilanz bei ei¬ ner praxisgerechten KTL-Anlage das erfindungsgemäße Verfahren dargestellt:In the following, the method according to the invention is shown by means of a material balance in a practice-oriented KTL system:
Beckenanlage: Gesamtinhalt: 150 m3Pool system: total volume: 150 m3
Ultrafiltrat pro Tag: 2 m3 Nachfüllmenge Dispersion/Tag: 4 t (Feststoffanteil 1,6 t; enthaltend 2,1 t Wasser)Ultrafiltrate per day: 2 m3 refill quantity of dispersion / day: 4 t (solid content 1.6 t; containing 2.1 t water)
Ultrafiltrat: Analyse ex TankwagenUltrafiltrate: analysis ex tanker
Festkörpergehalt : 0,6 %Solids content: 0.6%
Harzanteile: 0,5 % Schwermetalle (Blei): 0,1 %Resin proportions: 0.5% heavy metals (lead): 0.1%
Analyse nach Vorbehandlung (Ausfällung)Analysis after pre-treatment (precipitation)
Festkörpergehalt: 0,5 % Harzanteile: 0,5 % Schwermetalle:Solids content: 0.5% resin content: 0.5% heavy metals:
Wiedereinsatz: Durch Wiederverwertung von 2 m3 des vorbehandelten Ultrafiltrats für die Dispergierung und Verdünnung des Haupt- bindemittels werden 4 t Dispersion hergestellt. Die restlichen 0,1 t Wasser werden in Form von deionisiertem Wasser eingesetzt. Reuse: By recycling 2 m 3 of the pretreated ultrafiltrate for the dispersion and dilution of the main binder, 4 t of dispersion are produced. The remaining 0.1 t of water are used in the form of deionized water.

Claims

Patentansprüche: Claims:
1. Verfahren zur abwasserfreien Badführung bei Anlagen zur kathodischen Elektrotauchlackierung, dadurch ge- kennzeichnet, daß man zur Dispergierung der einge¬ setzten Bindemittel- und/oder Lackkomponenten das gesamte, beim Betrieb der Anlagen anfallende Ultra¬ filtrat verwendet, mit der Maßgabe, daß bei Verwen¬ dung des Ultrafiltrats für bleifreie Lackformulie- rungen die gegebenenfalls vorhandenen Bleisalze vor¬ her entfernt werden.1. Process for wastewater-free bath management in systems for cathodic electrocoating, characterized in that the entire ultra-filtrate obtained during operation of the systems is used to disperse the binder and / or coating components used, with the proviso that at If the ultrafiltrate is used for lead-free paint formulations, the lead salts which may be present are removed beforehand.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man das Ultrafiltrat zur Dispergierung von Bin- demittel- und/oder Lackkomponenten verwendet, die einen zumindest ähnlichen chemischen Aufbau der Bin¬ demittel aufweisen, wie das Lackmaterial, dem das Ultrafiltrat entstammt. 2. The method according to claim 1, characterized in that one uses the ultrafiltrate for the dispersion of binder and / or lacquer components which have at least a similar chemical structure of the binder as the coating material from which the ultrafiltrate originates.
PCT/AT1991/000047 1990-03-26 1991-03-25 Process for sewage-free operation of baths in installations for cathodic electrophoretic enamelling WO1991014807A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT0069790A AT395605B (en) 1990-03-26 1990-03-26 METHOD FOR WATER-FREE BATHING IN SYSTEMS FOR CATHODIC ELECTRO-DIP PAINTING
ATA697/90 1990-03-26

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Publication Number Publication Date
WO1991014807A1 true WO1991014807A1 (en) 1991-10-03

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EP (1) EP0521956A1 (en)
AT (1) AT395605B (en)
AU (1) AU7549991A (en)
WO (1) WO1991014807A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4409270C1 (en) * 1994-03-18 1995-03-30 Herberts Gmbh Process for effluent-free coating by cataphoretic deposition

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2326330A1 (en) * 1972-05-24 1973-12-06 Hajtomu Es Felvonogyar Electrophoretic bath fluid recovery - by rinsing with deionised fluid tapped from main bath circuit
DE2313751A1 (en) * 1973-03-20 1974-10-03 Basf Farben & Fasern Electrophoretic dip coating process of workpieces - using anion exchanger treated ultra filtrate for flushing, giving improved coating

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE759416A (en) * 1969-11-25 1971-05-25 Ppg Industries Inc PROCESS FOR EXCHANGING ION OF AN ULTRAFILTRATE FROM AN ELECTROLYTIC DEPOSIT BATH
JPS54134749A (en) * 1978-04-12 1979-10-19 Nissan Motor Co Ltd Cationic type electrodeposition coating

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2326330A1 (en) * 1972-05-24 1973-12-06 Hajtomu Es Felvonogyar Electrophoretic bath fluid recovery - by rinsing with deionised fluid tapped from main bath circuit
DE2313751A1 (en) * 1973-03-20 1974-10-03 Basf Farben & Fasern Electrophoretic dip coating process of workpieces - using anion exchanger treated ultra filtrate for flushing, giving improved coating

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4409270C1 (en) * 1994-03-18 1995-03-30 Herberts Gmbh Process for effluent-free coating by cataphoretic deposition

Also Published As

Publication number Publication date
ATA69790A (en) 1992-06-15
AU7549991A (en) 1991-10-21
AT395605B (en) 1993-02-25
EP0521956A1 (en) 1993-01-13

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