WO1988004958A1 - Process for coating surfaces with a thick layer of fine liquid droplets - Google Patents

Process for coating surfaces with a thick layer of fine liquid droplets Download PDF

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Publication number
WO1988004958A1
WO1988004958A1 PCT/EP1987/000796 EP8700796W WO8804958A1 WO 1988004958 A1 WO1988004958 A1 WO 1988004958A1 EP 8700796 W EP8700796 W EP 8700796W WO 8804958 A1 WO8804958 A1 WO 8804958A1
Authority
WO
WIPO (PCT)
Prior art keywords
liquid droplets
fine liquid
thick layer
corona
coating surfaces
Prior art date
Application number
PCT/EP1987/000796
Other languages
German (de)
French (fr)
Inventor
Ernst-Günter LIERKE
Rudolf Grossbach
Rolf Hartmann
Klaus-Dieter LÜHMANN
Original Assignee
Battelle-Institut E.V.
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 Battelle-Institut E.V. filed Critical Battelle-Institut E.V.
Publication of WO1988004958A1 publication Critical patent/WO1988004958A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B17/00—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups
    • B05B17/04—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods
    • B05B17/06—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations
    • B05B17/0607—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/08—Plant for applying liquids or other fluent materials to objects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/007—Processes for applying liquids or other fluent materials using an electrostatic field
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
    • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
    • B05D1/045—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field on non-conductive substrates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/14—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by electrical means
    • B05D3/141—Plasma treatment
    • B05D3/142—Pretreatment

Definitions

  • the invention relates to a method for densely covering a surface of a body made of insulator material with fine liquid droplets, these being produced by ultrasonic nebulization, then electrically charged via a corona tip by a corona discharge and then being electrostatically deposited on the surface.
  • This method is used for the surface treatment of any shaped solid, in particular for the purpose of chemical or physical modification or also for dyeing, printing, coating and the like.
  • Such a method is known from DE-OS 34 14 245 of the applicant. It has proven itself in and of itself.
  • the invention is therefore based on the object of a method having the features mentioned at the outset to propose, with which practically any amount of aerosol, possibly also from non-conductive liquids, can be completely and evenly deposited on surfaces consisting of insulator material.
  • the invention is characterized in that the corona tip causing the corona discharge is applied alternately to positive and to negative voltage.
  • the previously observed extinction of the corona discharge and thus the limitation of the separation effect are reliably prevented and any amount of fine aerosols can be deposited on the insulator surface.
  • the aerosol flow is alternately charged with electrons or positive gas ions and, in both cases, is conducted in the field between the corona tip and the ground electrode to the insulator surface in between and is deposited there.
  • the polarity of the corona tip should be changed after a measurable decrease or after the corona current has gone out due to field shielding.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Electrostatic Spraying Apparatus (AREA)

Abstract

A process for coating a surface of insulating material with a thick layer of fine liquid droplets generated by ultrasonic atomization, then electrically charged with alternating polarities and finally electrostatically deposited on the surface. By using an alternating polarity, practically any desired quantity of aerosol can be completely and very uniformly deposited.

Description

Verfahren zum dichten Belegen einer Oberfläche mit feinen Flüssigkeitströpfchen Process for the dense covering of a surface with fine liquid droplets
Beschreibungdescription
Die Erfindung betrifft ein Verfahren zur dichten Belegung einer aus Isolatormaterial bestehenden Oberfläche eines Körpers mit feinen Flüssigkeitströpfchen, wobei diese durch Ultraschallvernebelung erzeugt, anschließend über eine Koronaspitze durch eine Koronaentladung elektrisch aufgeladen und dann elektrostatisch auf der Oberfläche abgeschieden werden.The invention relates to a method for densely covering a surface of a body made of insulator material with fine liquid droplets, these being produced by ultrasonic nebulization, then electrically charged via a corona tip by a corona discharge and then being electrostatically deposited on the surface.
Dieses Verfahren dienr zur Oberflächenbehandlung beliebig geformter Festkörper, insbesondere zum Zwecke einer chemischen oder physikalischen Modifikation oder auch zum Färben, Drucken, Beschichten und dergleichen. Ein solches Verfahren ist bekannt durch die DE-OS 34 14 245 der Anmelderin. Es hat sich an und für sich bewährt.This method is used for the surface treatment of any shaped solid, in particular for the purpose of chemical or physical modification or also for dyeing, printing, coating and the like. Such a method is known from DE-OS 34 14 245 of the applicant. It has proven itself in and of itself.
Will man nach diesem bekannten Verfahren Oberflächen beschichten, die aus Isolatormaterial bestehen, so lädt sich jedoch nach einer gewissen Zeit die zu beschichtende, elektrisch isolierende Fläche durch die abgeschiedenen Aerosoltropfen mehr oder weniger schnell auf, und zwar in der Polarität der Aerosoltropfen, die vorher durch die Koronaentladung elektrisch negativ aufgeladen wurden. Nach einer gewissen Zeit können sich also keine Aerosoltropfen mehr abscheiden, weil durch die Flächenladung ein elektrisches, gleichpoliges Gegenfeld aufgebaut wurde, das die Feldstärke an der Koronaspitze abschirmt. Die Kbronaent- ladung erlischt dann und beendet die elektrostatische Aerosolaufladung und -abscheidung.If you want to coat surfaces made of insulator material according to this known method, however, after a certain time the electrically insulating surface to be coated will charge more or less quickly due to the separated aerosol drops, namely in the polarity of the aerosol drops that previously caused the corona discharge was negatively charged electrically. After a certain period of time, aerosol drops can no longer separate because the surface charge has created an electrical, equipolar opposing field that shields the field strength at the corona tip. The Kbrona discharge then goes out and stops the electrostatic aerosol charging and separation.
Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren mit den eingangs genannten Merkmalen vorzuschlagen, mit dem auch auf aus Isolatormaterial bestehenden Oberflächen praktisch beliebig viel Aerosol, gegebenenfalls auch aus nicht leitenden Flüssigkeiten, vollständig und gleichmäßig abgeschieden werden kann.The invention is therefore based on the object of a method having the features mentioned at the outset to propose, with which practically any amount of aerosol, possibly also from non-conductive liquids, can be completely and evenly deposited on surfaces consisting of insulator material.
Zur Lösung dieser Aufgabe ist die Erfindung dadurch gekennzeichnet, daß die die Koronaentladung bewirkende Koronaspitze abwechselnd an positive und an negative Spannung gelegt wird.To achieve this object, the invention is characterized in that the corona tip causing the corona discharge is applied alternately to positive and to negative voltage.
Dadurch wird das vorher beobachtete Erlöschen der Koronaentladung und damit die Begrenzung der Abscheidewirkung sicher verhindert und es können beliebige Mengen von Feinstaerosolen auf der Isolatorfläche abgeschieden werden. Der Aerosolstrom wird nämlich abwechselnd mit Elektronen bzw. positiven Gasionen geladen und in beiden Fällen im Feld zwischen der Koronaspitze und der Massenelektrode zu der dazwischen liegenden Isolatorfläche geführt und dort abgeschieden. Das Wechseln der Polarität der Koronaspitze soll nach einem meßbaren Rückgang oder nach dem Erlöschen des Koronastroms infolge Feldabschirmung erfolgen.As a result, the previously observed extinction of the corona discharge and thus the limitation of the separation effect are reliably prevented and any amount of fine aerosols can be deposited on the insulator surface. This is because the aerosol flow is alternately charged with electrons or positive gas ions and, in both cases, is conducted in the field between the corona tip and the ground electrode to the insulator surface in between and is deposited there. The polarity of the corona tip should be changed after a measurable decrease or after the corona current has gone out due to field shielding.
Die vorhergehende gegenpolare Flächenaufladung bewirkt nunmehr eine effektive Erhöhung der Feldstärke, die erst durch weitere Abscheidung allmählich wieder abgebaut wird, bis man diesem Effekt durch eine abermalige Umpolung wieder entgegenwirkt.The previous counter-polar surface charging now brings about an effective increase in the field strength, which is only gradually reduced again by further deposition, until this effect is counteracted again by reversing the polarity again.
Durch das periodische Umpolen der Koronaspitze läßt sich somit auf diese Weise selbst auf Nichtleitern beliebig vielBy periodically reversing the polarity of the corona tip, any amount can thus be obtained even on non-conductors
Aerosol vollständig und gleichmäßig abscheiden, und zwar auch bei Verwendung nicht leitender Flüssigkeiten als Aerosole. Bezüglich weiterer Einzelheiten der erfindungsgemäßen Verfahrensführung sei auf die Offenbarung der eingangs erwähnten deutschen Offenlegungsschrift 34 14 245 verwiesen. Separate the aerosol completely and evenly, even when using non-conductive liquids as aerosols. With regard to further details of the procedure according to the invention, reference is made to the disclosure of the German Offenlegungsschrift 34 14 245 mentioned at the beginning.

Claims

PatentanspruchClaim
Verfahren zur dichten Belegung einer aus Isolatormaterial bestehenden Oberfläche eines Körpers mit feinen Flüssigkeitströpfchen, wobei diese durch Ultraschailvernebelung erzeugt, anschließend über eine Koronaspitze durch eine Koronaentladung elektrisch aufgeladen und dann elektrostatisch auf der Oberfläche abgeschieden werden, dadurch gekennzeichnet, daß die die Koronaentladung bewirkende Koronaspitze abwechselnd an positive bzw. an negative Spannung gelegt wird. Process for the dense covering of a surface of a body made of insulator material with fine liquid droplets, these being produced by ultrasonic nebulization, then electrically charged via a corona tip by a corona discharge and then electrostatically deposited on the surface, characterized in that the corona tip causing the corona discharge alternately positive or negative voltage is applied.
PCT/EP1987/000796 1986-12-24 1987-12-18 Process for coating surfaces with a thick layer of fine liquid droplets WO1988004958A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19863644387 DE3644387C1 (en) 1986-12-24 1986-12-24 Process for the dense covering of a surface with fine liquid droplets
DEP3644387.5 1986-12-24

Publications (1)

Publication Number Publication Date
WO1988004958A1 true WO1988004958A1 (en) 1988-07-14

Family

ID=6317154

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1987/000796 WO1988004958A1 (en) 1986-12-24 1987-12-18 Process for coating surfaces with a thick layer of fine liquid droplets

Country Status (2)

Country Link
DE (1) DE3644387C1 (en)
WO (1) WO1988004958A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0411499A1 (en) * 1989-08-02 1991-02-06 Hoechst Aktiengesellschaft Process and device for coating a substrate

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2191311A1 (en) * 1972-06-27 1974-02-01 Scient Enterprises Inc
DE2247701A1 (en) * 1972-09-28 1974-04-11 Heinz Dr Haase METHOD AND DEVICE FOR APPLYING SOLID OR LIQUID PARTICLES TO SURFACES BY USING ELECTRIC FIELD FORCE
DE3414245A1 (en) * 1984-04-14 1985-10-17 Battelle-Institut E.V., 6000 Frankfurt Method and device for coating, in a sealed fashion, the surfaces of solids with fine droplets of fluid

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2191311A1 (en) * 1972-06-27 1974-02-01 Scient Enterprises Inc
DE2247701A1 (en) * 1972-09-28 1974-04-11 Heinz Dr Haase METHOD AND DEVICE FOR APPLYING SOLID OR LIQUID PARTICLES TO SURFACES BY USING ELECTRIC FIELD FORCE
DE3414245A1 (en) * 1984-04-14 1985-10-17 Battelle-Institut E.V., 6000 Frankfurt Method and device for coating, in a sealed fashion, the surfaces of solids with fine droplets of fluid

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0411499A1 (en) * 1989-08-02 1991-02-06 Hoechst Aktiengesellschaft Process and device for coating a substrate
US5110618A (en) * 1989-08-02 1992-05-05 Hoechst Aktiengesellschaft Process for electrostatically coating a substrate using an aerosol

Also Published As

Publication number Publication date
DE3644387C1 (en) 1988-04-14

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