EP0080307A2 - Appareil pour le revêtement électrostatique et procédé pour son utilisation - Google Patents

Appareil pour le revêtement électrostatique et procédé pour son utilisation Download PDF

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Publication number
EP0080307A2
EP0080307A2 EP82306034A EP82306034A EP0080307A2 EP 0080307 A2 EP0080307 A2 EP 0080307A2 EP 82306034 A EP82306034 A EP 82306034A EP 82306034 A EP82306034 A EP 82306034A EP 0080307 A2 EP0080307 A2 EP 0080307A2
Authority
EP
European Patent Office
Prior art keywords
applicator
blade
workpiece
medium
charging member
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.)
Withdrawn
Application number
EP82306034A
Other languages
German (de)
English (en)
Other versions
EP0080307A3 (fr
Inventor
Kenneth Robert Smythe
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.)
PEABODY INDUSTRIAL Ltd
Original Assignee
PEABODY INDUSTRIAL Ltd
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 PEABODY INDUSTRIAL Ltd filed Critical PEABODY INDUSTRIAL Ltd
Publication of EP0080307A2 publication Critical patent/EP0080307A2/fr
Publication of EP0080307A3 publication Critical patent/EP0080307A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • B05B5/087—Arrangements of electrodes, e.g. of charging, shielding, collecting electrodes
    • 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
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/053—Arrangements for supplying power, e.g. charging power
    • B05B5/0533—Electrodes specially adapted therefor; Arrangements of electrodes
    • 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
    • B05B5/10—Arrangements for supplying power, e.g. charging power
    • 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

Definitions

  • This invention relates to electrostatic blade coaters and to methods of electrostatically coating an article with a liquid.
  • blade as used herein is intended to have a wide meaning encompassing any suitable applicator provided with an edge from which the coating medium is discharged or drawn off.
  • a conventional electrostatic blade coater has an applicator blade which is supplied with a liquid and which incorporates an electrical conductor (also known as a charging electrode) for imparting to the liquid a high voltage charge.
  • the charged liquid is drawn off the blade edge and divides to form a mist of charged droplets which are attracted to the surface of the article to be coated.
  • an electrostatic blade coater has an applicator and electrostatic charging means for drawing off the blade a liquid to be coated on an article, the blade being substantially at earth potential.
  • a coater in accordance with the invention is therefore simpler and less hazardous than known coaters in which the electrostatic charge is applied to the liquid as the latter passes through or mover the applicator.
  • the electrostatic charging means may be of any convenient construction, e.g. an array of thin wires or a thin wire and a conductive sheet.
  • the charging means include a charging blade spaced from the applicator, itself in the form of a blade and acting not only to draw the liquid from the applicator blade but also to charge the liquid so that the liquid forms a finely divided mist of droplets which are drawn to an adjacent surface of the article to be coated by electrostatic attraction.
  • the charging blade may be spaced from the applicator blade by a distance of the order of 20 cm or more: a smaller spacing tends to cause arcing between the charging blade, which in use is typically at a voltage of the order of 90 kV, and the earthed applicator blade.
  • the liquid may be fed e.g. from the interior of the applicator blade by gravity to the edge of the applicator blade, being evenly distributed along the complete length thereof before being drawn off the edge, the edge being in the form of an overflow, hereafter called a "weir".
  • An alternative arrangement is for the liquid to issue from a series of spaced nozzles, such as hypodermic needles, of interchangeable size, the nozzles then replacing the blade edge or weir previously mentioned.
  • the article to be coated is passed along a generally straight line through the coater there being an applicator and a charging member on either side of the article.
  • the direction of the path of movement may be horizontal or vertical, or inclined to the horizontal and vertical.
  • the lower applicator and charging member are preferably supplemented by a further member, herein called a booster blade, positioned to influence the path of movement and spread or distribution of the liquid in its passage from the applicator to the article to be coated.
  • the polarity of the voltage supplied to the booster blade may be the same as or opposite to the polarity of the voltage supplied to the charging blade.
  • Each applicator (blade) is preferably longer than the width of the article to be coated to ensure that the marginal areas of the article are effectively coated with the liquid.
  • a method of electrostaically coating an article with a liquid comprises applying an electrostatic charge to the liquid after the latter has been drawn off or discharged from an applicator and before the liquid has reached the article.
  • the electrostatic charge is preferably applied to the liquid by means of a charging blade, arranged substantially parallel to the applicator but spaced therefrom sufficiently to avoid arcing between the charging blade and the applicator.
  • the coater applies a coating of an aqueous electrically conducting liquid to both sides of a flat, elongated article, such as steel strip, shown in broken lines.
  • the strip passes in this example through the coater along a generally horizontal path in the direction X -X.
  • the liquid is supplied from a transfer pump 10 through tachogenerator-controlled metering pumps 11 and pipes 2 and 3 to upper and lower applicator blades 4 and 5.
  • Each blade 4 and 5 extends generally horizontally and has along its length a series of holes from which the liquid issues, so that the distribution of liquid is even along the length of each blade.
  • Each blade 4 and 5 has a thin edge 4a or 5a forming a weir over which the liquid passes.
  • the liquid is attracted away from the edge 4a of the upper blade 4 and into an electrostatic field developed by a horizontal charging blade 6 at a negative potential of about 90 kV.
  • the blade 6 is parallel to and spaced from the blade 4 by a distance of about 20cm, and the blade 6 is slightly below the blade 4.
  • the liquid, finely divided into charged droplets forms a mist which is attacted to the upper surface of the steel strip which is at earth potential.
  • a similar, lower charging blade 7 is parallel to and spaced from the lower applicator blade 5.
  • the blade 7 is also at a negative potential of about 90 kV and generates an electrostatic field into which the liquid is drawn after it leaves the edge 5a of the blade 5.
  • a horizontal booster blade 8 is also charged to a potential of 90 kV and is positioned at the same general horizontal level as the blade 7, but on the opposite side of the blade 5.
  • the voltage applied to the booster blade 8 is of positive polarity but it may also be of negative polarity.
  • the voltages to the blades 4 to 8 are supplied from high voltage transformers 12.
  • Both of the applicator blades 4 and 5 are at earth potential and so is the liquid supply system upstream of the blades 4 and 5. This is possible even though the liquid is electrically conductive by applying the electrical charge to the liquid after the latter has left the applicator blades, rather than as the liquid passes over the applicator blades as in the prior art.
  • the described electrostatic blade coater can be operated outdoors; rain would not interfere with the operation.
  • the described electrostatic blade coater has no moving parts downstream of the metering pumps and is both efficient and safe.
  • the material sprayed may include slurries and powders.

Landscapes

  • Application Of Or Painting With Fluid Materials (AREA)
  • Electrostatic Spraying Apparatus (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Physical Vapour Deposition (AREA)
EP82306034A 1981-11-20 1982-11-12 Appareil pour le revêtement électrostatique et procédé pour son utilisation Withdrawn EP0080307A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8135054 1981-11-20
GB8135054 1981-11-20

Publications (2)

Publication Number Publication Date
EP0080307A2 true EP0080307A2 (fr) 1983-06-01
EP0080307A3 EP0080307A3 (fr) 1983-11-16

Family

ID=10526043

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82306034A Withdrawn EP0080307A3 (fr) 1981-11-20 1982-11-12 Appareil pour le revêtement électrostatique et procédé pour son utilisation

Country Status (2)

Country Link
EP (1) EP0080307A3 (fr)
JP (1) JPS58104655A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107309108A (zh) * 2017-07-07 2017-11-03 首钢京唐钢铁联合有限责任公司 一种镀锡板的表面涂油方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2684656A (en) * 1949-07-30 1954-07-27 Ransburg Electro Coating Corp Electrostatic coating apparatus
US2773472A (en) * 1951-08-14 1956-12-11 Gen Motors Corp Apparatus for electrostatic spray coating
US3017114A (en) * 1958-08-26 1962-01-16 Gen Motors Corp Electrostatic paint spray
BE677461A (fr) * 1965-03-09 1966-08-01
FR2243740A1 (fr) * 1973-09-14 1975-04-11 Voith Gmbh
FR2446680A1 (fr) * 1979-01-22 1980-08-14 Canadian Patents Dev Appareil de pulverisation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2684656A (en) * 1949-07-30 1954-07-27 Ransburg Electro Coating Corp Electrostatic coating apparatus
US2773472A (en) * 1951-08-14 1956-12-11 Gen Motors Corp Apparatus for electrostatic spray coating
US3017114A (en) * 1958-08-26 1962-01-16 Gen Motors Corp Electrostatic paint spray
BE677461A (fr) * 1965-03-09 1966-08-01
FR2243740A1 (fr) * 1973-09-14 1975-04-11 Voith Gmbh
FR2446680A1 (fr) * 1979-01-22 1980-08-14 Canadian Patents Dev Appareil de pulverisation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107309108A (zh) * 2017-07-07 2017-11-03 首钢京唐钢铁联合有限责任公司 一种镀锡板的表面涂油方法

Also Published As

Publication number Publication date
EP0080307A3 (fr) 1983-11-16
JPS58104655A (ja) 1983-06-22

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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PUAL Search report despatched

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18D Application deemed to be withdrawn

Effective date: 19840717

RIN1 Information on inventor provided before grant (corrected)

Inventor name: SMYTHE, KENNETH ROBERT