US3674543A - Electrodeposition - Google Patents

Electrodeposition Download PDF

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Publication number
US3674543A
US3674543A US64687A US3674543DA US3674543A US 3674543 A US3674543 A US 3674543A US 64687 A US64687 A US 64687A US 3674543D A US3674543D A US 3674543DA US 3674543 A US3674543 A US 3674543A
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electrodeposition
bath
electrode
particles
vessel
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US64687A
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Masamichi Sato
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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
    • C25D13/00—Electrophoretic coating characterised by the process

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  • US. Cl. 117-93 7 Claims ABSTRACT OF THE DISCLOSURE A method of electrodepositing a coating onto a substrate from a bath of coating particles suspended in an electrically insulating liquid by immersing the substrate either wholly or partially into the bath.
  • a pair of electrodes are provided on either side of the substrate but insulated from it.
  • One electrode may contact the bath, for instance it may lie inside the container or be the container.
  • the other electrode is supported outside of the bath.
  • a potential is applied to the electrodes sufiicient to cause a corona discharge through the bath whereby the particles are electrophoretically moved to and deposited on the substrate.
  • the instant invention pertains to a novel and highly practicable method of electrodeposition in which the electrostatic induction of solids in an electrically insulating liquid is utilized.
  • the electrically insulating liquid contains pigment particles, a charge controlling agent, and a binder agent that coat the pigment particles or is dissolved or dispersed in the insulating liquid.
  • An article to be coated is immersed in the deposition bath as an electrode and an electric potential is applied between the electrode of the article and another electrode disposed in the bath, whereby pigment particles are attracted onto the surfaces of the article by the action of electrophoresis.
  • FIG. 1 is a schematic cross-sectional view showing a mode of electrodeposition that has most generally been employed.
  • FIG. 2 is a schematic cross-sectional view showing an embodiment of the electrodeposition method of the instant invention.
  • FIG. 3 is a schematic view showing the principle of the electrodeposition method of this invention.
  • FIGS. 4-9 are cross-sectional views each showing other embodiment of the electrodeposition method of this invention.
  • FIG. 1 is a schematic cross-sectional view of the simplest example of conventional electrodeposition methods
  • particles 10 which may be solids, emulsion, emulsoid, colloid or high molecular weight material are suspended or dissolved in a liquid 11 by a conventional means such as a 'kneading or dispersing treatment usually employed in the production of paints or inks.
  • the liquid 11 is a liquid or a liquid mixture having comparatively high electric resistance and is in an insulating vessel 12.
  • An electrode 14 is immersed in the liquid with a proper interval with an electrode 13 that is also immersed in the liquid.
  • the par ticles 10 When an electric potential is applied between the electrodes 13 and 14 (usually SOD-100,000 volts), the par ticles 10 are attracted to the electrode 14 by the action of electrophoresis if the particles are charged positively and a thick deposition is formed on the electrode 14.
  • the deposition is comparatively thicker in the side of the electrode 14 having to the electrode 13 but comparatively thinner at the opposite side thereof.
  • the deposition becomes uneven and the whole surfaces of the electrode are coated by the electrodeposition.
  • an object of this invention is to provide an electrodeposition method without the above-mentioned demerits, that is to say, an electrodeposition method than can deposit onto either only one side or the whole sides of an article to be deposited or coated and that it is not required to connect a wire to the article to be deposited, which results in avoiding the electrode from being stained.
  • the electrodeposition method of this invention which comprises disposing a corona discharging electrode at the outside of an electrodeposition bath prepared by incorporating particles in an electrically insulating liquid, said particles being able to move freely in the liquid, together with, if necessary, a charge-controlling agent in the state of coating said particles or being dissolved or suspended in the liquid, a dispersion stabilizer, and a binder; placing an article to be electrodeposited between said corona discharging electrode and an opposite electrode, said article being electrically insulated from both electrodes and also being locally or wholly immersed in said electrodeposition bath, and then applying an electric po tential between the two electrodes to cause corona discharge, whereby the particles are moved to the article by the action of electrophoresis and deposited there.
  • FIG. 2 is a schematic cross-sectional view showing the simplest embodiment of the method of this invention.
  • a corona discharge electrode 20 is disposed over an electrodeposition bath 11 and as the electrode, a needlelike, wire-like, knife-shaped, or strip-like electrode is used so that when a proper electric potential (usually 1,000- 100,000 volts) is applied, an extremely uneven electric field is formed to cause corona discharge.
  • a proper electric potential usually 1,000- 100,000 volts
  • a needle-shaped electrode 20 is used.
  • a vessel 21 is made of a metal and has an action of the opposite electrode.
  • An article 22 to be deposited is electrically insulated from the electrodes 20 and 21 and in this embodiment the article is a metal plate.
  • the article 22 is electrically connected to the electrode 21 through the electrodeposition bath, in other words, the article 22 can be said to be connected to the electrode 21 through the resistance of the electrodeposition bath.
  • the embodiment shown in FIG. 2 is the case where particles 10 have positive charge and a negative potential is applied to the corona discharge electrode 20.
  • corona discharge is generated at the top of the electrode 20 and corona ions are directed to the surface of the electrodeposition bath, whereby polarized charges are formed on the surfaces of the metal plate 22 and the positively charged particles are uniformly deposited to the lower surface of the metallic plate 22 having the negative polarized charge, while no particles are deposited on the upper surface thereof having the positive polarized charge.
  • FIG. 3 is illustrated an enlarged cross-sectional view of the metal plate 22 in FIG. 2 for showing the principle of the method of this invention.
  • FIG. 4 is a schematic view showing other embodiments of this invention.
  • an article 40 to be deposited is floated on an electrodeposition bath 11, that is to say, the lower portion of the article is immersed in the electrodeposition bath and the upper portion of'the article is outside the bath. Even if a part of the article to be electrodeposited is outside the electrodeposition bath as in this embodiment, polarized charges are formed by corona discharging and particles can be deposited on the lower surface of the article.
  • the article 40 may be electrodeposited without connecting the article to a wire while floating and moving the article. Therefore, the embodiment is suitable for mass production.
  • FIG. 5 is a schematic sectional view showing a practical embodiment of this invention for conducting the electrodeposition on the outside surface of a vessel 50.
  • a corona discharging electrode 20' is disposed in the vessel 50 and the electrode is electrically insulated from the vessel 50.
  • the vessel 50 contains no electrodeposition liquid in it but the electrodeposition liquid present outside the vessel.
  • the vessel 50 may contain the same electrodeposition liquid.
  • An electrodeposition bath is placed in other vessel 21 which acts as an opposite electrode and the vessel 50 to be deposited is immersed in the electrodeposition bath as shown in FIG. 5. When an electric potential is applied between the corona electrode and the vessel 21, corona discharge is generated and the particles are deposited on the outside surface of the vessel 50.
  • FIG. 6 is a schematic cross-sectional view showing a practical embodiment of the method of this invention in which the inside and the outside surfaces of a vessel 61 are simultaneously deposited by particles having different colors respectively.
  • the vessel 61 is made of a. material through which the electrodeposition liquid are not leaked.
  • An electrodeposition bath containing particles having positive charge is filled in vessel 21 as in the above embodiments and the vessel 61 to be deposited is immersed in the electrodeposition bath 11.
  • Other electrodeposition bath 60 containing particles having negative charge.
  • the particles in the both electrodeposition baths are deposited on the both surfaces of the vessel 61 simultaneously and in this case if the particles in the both electrodeposition baths are so selected that the color of the one is different from the other, the inside surface and the outside surface of the vessel 61 can be deposited by the particles of diiferent colors respectively.
  • FIG. 7 is a cross-sectional view showing a practical embodiment of the electrodeposition method of this invention for depositing same kind of particles onto the both sides of an article 70.
  • the article 70* is a vertically elongated rod-shaped, plate-shaped or cylindrical one and in the embodiment the whole surfaces of the article immersed in the electrodeposition bath can be deposited by the particles.
  • FIG. 8 is a modification of the embodiment shown in FIG. 7. That is to say, a plate-shaped article is suspended horizontally in the electrodeposition bath by means of a conductive member 81 and is completely immersed in the bath. A corona discharging electrode 20 is disposed near the top of the conductive member 81. When an electric potential is applied to the corona discharging electrode 20 and the opposite electrode 21 to cause corona discharging, the particles are deposited on the whole surfaces of the article 80.
  • FIG. 9 shows still other example of the electrodeposition method of this invention.
  • An opposite electrode 92 is disposed at the outside of an insulating vessel 91 containing an electrodeposition bath 11 and by applying a proper electric potential to a corona discharge electrode 20 and the opposite electrode 92, similar electrodeposition can be practiced.
  • the opposite electrode is disposed at the outside of the insulating vessel but it may be placed at the inside of the vessel.
  • One feature of the instant invention is to use corona discharge and even if a high electric potential is applied to the corona discharge electrode, the electrodeposition is not eifected if corona discharge is not generated.
  • the coatings formed by the electrodeposition may be fixed by solvent or heating and also may be hardened by utilizing a condensation polymerization after deposition.
  • EXAMPLE 1 An electrodeposition liquid was filled in a metal vessel having a fiat bottom and an insulating frame of a hard vinyl chloride resin having a height of 1 cm. was placed on the bottom of the vessel. A metal plate having a thickness of 2 mm. was placed on the frame and in this state the depth of the electrodeposition liquid over the surface of the metal plate was 1 cm. A metal needle was disposed over the electrodeposition bath so that the top of the metal needle was disposed about 5 mm. over the level of the electrodeposition bath. An electric potential of 7 kv. was applied to the metal needle while earthing the metal vessel and after about 30 seconds, the application of the electric potential was stopped and the metal plate was withdrawn from the bath.
  • the electrodeposition bath used above was prepared by the following manner:
  • the particles When a negative electric potenial was applied to the needle electrode, the particles were deposited on to the only lower surface of the metal plate as mentioned above but when a positive potential was applied to the needle electrode, the particles were deposited onto only the upper surface of the metal plate but were not deposited onto the lower surface thereof.
  • EXAMPLE 2 The electrodeposition was conducted according to the embodiment shown in FIG. 7. An electrodeposition liquid was filled in a metal vessel and a metal rod was immersed locally in the liquid in the depth of 10 cm. The length of the rod above the level of the liquid was about 2 cm. and the depth of the bath from the lower end of the rod to the bottom of the vessel was about 2 cm. The rod was suspended by means of an insulating cord. A needle elec trode was disposed over the metal rod so that the end of the needle electrode was positioned about 5 mm. over the top of the metal rod. A direct current potential of +9 kv. was applied to the needle electrode while earthing the vessel and after about 20 seconds the application of the electric potential was stopped and the metal rod was withdrawn from the bath.
  • a thick deposition was obtained on the surface of the portion of the metal rod immersed in the electrodeposition bath.
  • the metal rod thus withdrawn was dried, placed in a vessel filled with a butyl acetate vapor for 20 seconds, and dried in air again, whereby strongly electrodeposited coating is obtained.
  • the electrodeposition bath used above was prepared by the following manner:
  • Soybean oil-modified medium oil-length alkyd resin 20 Butyl acetate 100 The above ingredients were mixed for 4 hours in a ball mill and the paste thus prepared was dispersed in 10,000
  • a method of electrodeposition which comprises disposing a corona discharging electrode at the outside of an electrodeposition bath prepared by incorporating particles in an electrically insulating liquid, said particles being able to move freely in the liquid placing an article to be electrodeposited between said corona discharging electrode and an opposite electrode, said article being electrically insulated from the both electrodes and also being locally or wholly immersed in said electrodeposition bath, and then applying an electric potential between the both electrodes to cause corona discharge, whereby the particles are moved to the article by the action of electrophoresis and deposited thereon.
  • the electrodeposition bath contains additionally a charge-controlling agent in the state of coating said particles or being dissolved or suspended in the liquid, a dispersion stabilizer, and a binder.
  • a vessel for the electrodeposition bath is made of a conductive material and said vessel is utilized as the opposite electrode 4.
  • a vessel for the electrodeposition bath is made of an insulating material and the opposite electrode is disposed at the outside or the inside of the vessel.

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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)
  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
US64687A 1969-08-18 1970-08-18 Electrodeposition Expired - Lifetime US3674543A (en)

Applications Claiming Priority (1)

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JP44064832A JPS496182B1 (fr) 1969-08-18 1969-08-18

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US3674543A true US3674543A (en) 1972-07-04

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US (1) US3674543A (fr)
JP (1) JPS496182B1 (fr)
BE (1) BE754971A (fr)
CA (1) CA918600A (fr)
DE (1) DE2041020A1 (fr)
FR (1) FR2058355B1 (fr)
GB (1) GB1270608A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115312658A (zh) * 2022-08-18 2022-11-08 南方科技大学 复合极化装置以及复合压电材料的极化方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3477934A (en) * 1966-06-29 1969-11-11 Xerox Corp Imaging process
DE1790220C3 (de) * 1968-09-30 1978-12-07 Hoechst Ag, 6000 Frankfurt Verfahren und Vorrichtung zum elektrostatischen Beschichten von Oberflächen mit elektrisch leitendem, halb- oder nichtleitendem Material

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115312658A (zh) * 2022-08-18 2022-11-08 南方科技大学 复合极化装置以及复合压电材料的极化方法

Also Published As

Publication number Publication date
BE754971A (fr) 1971-02-01
JPS496182B1 (fr) 1974-02-13
GB1270608A (en) 1972-04-12
CA918600A (en) 1973-01-09
FR2058355A1 (fr) 1971-05-28
FR2058355B1 (fr) 1973-11-23
DE2041020A1 (de) 1972-01-27

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