US3730866A - Catholyte rinse of electrocoat - Google Patents

Catholyte rinse of electrocoat Download PDF

Info

Publication number
US3730866A
US3730866A US00887949A US3730866DA US3730866A US 3730866 A US3730866 A US 3730866A US 00887949 A US00887949 A US 00887949A US 3730866D A US3730866D A US 3730866DA US 3730866 A US3730866 A US 3730866A
Authority
US
United States
Prior art keywords
bath
paint
catholyte
coating
article
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
US00887949A
Other languages
English (en)
Inventor
L Madejczyk
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.)
EIDP Inc
Original Assignee
Ford Motor Co
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 Ford Motor Co filed Critical Ford Motor Co
Application granted granted Critical
Publication of US3730866A publication Critical patent/US3730866A/en
Assigned to E. I. DU PONT DE NEMOURS AND COMPANY reassignment E. I. DU PONT DE NEMOURS AND COMPANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: FORD MOTOR COMPANY
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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

Definitions

  • the coated object is withdrawn from the coating bath and takes with it a quantity of adhered or otherwise entrapped paint which is not a part of the electrodeposited paint iilm thereon.
  • This material is conventionally removed by rinsing and/or by compressed' air streams.
  • This material together with the rinse water conventionally drains into the plant waste system or is otherwise disposed of.
  • coating bath liquid which has been freed or substantially freed of paint solids is particularly suitable for use as rinse liquid for an electrocoating process. It" this material is then returned to the bath with undeposited paint removed from a coated article through rinsing, it maintains the water balance of the bath and can be controlled so as not to introduce extraneous contaminants, always a potential danger if a new supply of water is being continuously added to the bath.
  • liquid is separated from the bath which is free or substantially free of paint solids.
  • This liquid is continuously or intermittently continuously pumped to a rinsing station constructed and arranged so that the rinse liquid and paint particles rinsed from the coated workpiece flow back into the coating bath and are redispersed.
  • catholyte separation unit which comprises a water permeable wall and includes a cathode in electrical connection with the primary cathode of the coating cell.
  • This auxiliary cathode assumes the polarity of 3,730,866 Patented May 1, 1973 ice the primary and may or may not be a part of the water permeable wall.
  • Suitable binder resins for anodic deposition are synthetic polycarboxylic acid resins, i.e., organic resins having free or ionizable carboxyl groups in their molecular structure which are derived from a constitutent monomer.
  • Acidic hlm-forming resins include, but not by way of limitation, any of the polycarboxylic acid resins used in the electrodeposition of paint from an aqueous bath.
  • Coupled oils such as sunower, safower, perilla, hempseed, walnut seed, dehydrated castor oil, rapeseed, tomato seed, menhaden, corn, tung, soya, oiticica, or the like, the oleiinic double bonds in the oil being conjugated or nonconjugated or a mixture
  • the coupling agent being an acyclic oleiinic acid or anhydride, preferably maleic anhydride, but also crotonic acid, citraconic acid, or anhydride, fumaric acid, or an acyclic -olefinic aldehyde or ester of an acyclic olefinic ester such as acrolein, vinyl acetate, methyl maleate, etc., or even a polybasic acid such as phthalic or succinic, particularly coupled glyceride oils that are further reacted with about 2 to about 25% of a polymerizable vinyl monomer; maleinized unsaturated fatty acids
  • Cathodically depositable resins include those having ionizable amine groups in their molecular structure. They can be-dispersed in aqueous dispersion with the aid of a water soluble acid, e.g., acetic acid.
  • FIG. 1 is a semidiagrammic sectional side view of apparatus used in carrying out one embodiment of this invention
  • FIG. 2 is a sectional view taken along line 2--2 of FIG. 1;
  • FIG. 4 is a semidiagramrnatic sectional side view ofl apparatus used in carrying out a second embodiment of this invention and taken along line 4-4 of FIG. 5
  • FIG. 5 is a view taken along line 5-5 of FIG. 4;
  • FIG. 6 is a view taken along line 6-6 of FIG. 5 and is a partial end view of the apparatus shown in FIG. 4 and looking inthe direction of workpiece travel to and through the coating bath.
  • a steel coating tank 11 contains a coating bath 13, i.e., an aqueous dispersion of paint comprising pigment, a polycarboxylic acid resin and a water soluble base, and serves as a negative electrode (cathode) in the coating process.
  • Tank 11 is electrically connected to D.C. power supply unit 17 via conductor 15.
  • An article 19 to be coated e.g., an automotive body, is shown suspended from a conveyor 35 by hanger 21.
  • Conveyor 35 is a conventional, electrically powered, chain driven conveyor constructed and arranged for the transportation of articles to be coated through bath 13.
  • Hanger 21 includes insulator 23 which electrically insulates article 19 from the grounded conveyor.
  • Contact plate or brush 25 is attached to and in electrical connection with hanger 21.
  • Article 19 is shown immersed in bath 13 and in electrical connection with bus bar 37 via contact plate 25 and in turn is in electrical connection with D.C. power supply unit 17 via conductor 39.
  • Article 19, therefore serves as the positive electrode of an electrodeposition cell while the article is passing through bath 13.
  • bus bar 37 may be segmented and that certain of the various segments thereof may have no connection with power unit 17 or another power supply unit not shown so as to permit impression of a higher voltage than that impressed on other segments, or may be electrically connected with a power supply unit so as to admit of polarity reversal with respect to other segments of the bus bar.
  • Power supply unit 17 is constructed and arranged to convert (rectify) an alternating current power source to direct electric current or the equivalent thereof and to provide between the electrodes and through the coating bath a direct current ow of electrical energy that is commensurate with the size of the electrocoating operation contemplated.
  • Design of the power supply unit should take into consideration the surface area of the workpieces that will be in residence within the coating bath at any given time, the workpiece surface area entering the bath per unit time, the deposition properties of the coating formulation, the conductivity of the coating bath, the thickness of the coating to be formed, etc.
  • Catholyte separation unit 40 Positioned along one upper side of tank 11 is a catholyte separation unit 40.
  • Catholyte separation unit 40 comprises a porous metal box, e.g., expanded metal or wire mesh, and a separation membrane 43 which admits of the passage of water and water soluble materials such as amines, KOH, LiOH, NaOH, etc., therethrough while preventing the passage of substantial amounts of paint solids.
  • separator membrane 43 may be cloth, e.g., sailcloth, water permeable plastic membranes, and other water permeable synthetic or natural lter means.
  • the separation membrane is the porous or water permeable box itself and is structured so that the openings therein are suciently small to efrect the same degree of separation specified for the separate separation membranes.
  • the walls of separation unit are formed of a porous ceramic and a conductor positicned inside such unit is in electrical connection with the primary cathode.
  • the separation membrane 43 may be structured to provide an essentially complete barrier to the paint particles of bath 13 or it may admit of their limited passage to a degree such that the concentration of such particles in catholyte separation unit 40 is below about 50, preferably below l0 and more preferably below 5, percent of the corresponding concentration in coating bath 13. Otherwise exxpressed there exists through the barrier of differential ow with respect to water and solubilizer or resin dispersal assistant on the one hand and paint solids on the other.
  • Pumping means 45 Positioned within catholyte separation unit are pumping means 45 having intake means 47. Pumping means 45 is operatively connected to conduit 49 through which liquid from within catholyte separation unit 40 is passed by pumping means 45 to conduits 51 and 53 and through the same to shower heads 55 and 57 from whence the same is discharged upon article 27. In this embodiment, article 27 is thus rinsed while immediately over the coating bath and hence the drainage from such rinsing falls directly into coating bath 13. Conduit 49 is provided with valve 49-1 which can divert the flow from pump 45 through outlet conduit 49-2 for purging.
  • Porous metal box 41 is supported by and in electrical connection with the coating tank 11. Thus, it becomes a part of the cathode of the cell and attracts cations through separation membrane 43, primarily those of the water soluble base employed to disperse and/or solubilize the acidic paint binder resin. Thus, within catholyte separation unit 40, there exists an aqueous dispersion that is paint solids poor and base rich relative to bath 13. This fluid is therefore particularly suitable as a rinse uid for removing adhered paint particles from the coated workpiece.
  • FIGS. 4, 5 and 6 relate to a second embodiment of this invention,
  • a steel coating tank 111 which contains coating bath 113 and serves as the negative electrode in the coating process.
  • Tank 111 is electrically connected to D.C. power supply unit 117 via conductor 115.
  • An article to be coated 119 is shown suspended from a conveyor 135 by hanger 123.
  • Conveyor 135 is a conventional, electrically powered, chain driven conveyor constructed and arranged for the transportation of articles to be coated through bath 13.
  • Hanger 121 includes insulator 123 which electrically insulates article 119 from the grounded conveyor.
  • Contact plate or brush 125 is attached to and in electrical connection with hanger 121.
  • Article 119 is shownimmersed in bath 113 and in electrical connection with bus bar 137 via contact plate 125 and in turn is in electrical connection with D.C. power supply unit 117 via conductor 139.
  • Article 119 therefore, serves as the positive electrode of an electrodeposition cell while the article is passing through bath 113.
  • a drainboard assembly 112 constructed and arranged so that rinse liquid falling thereon drains back into coating bath 113 in coating tank 111.
  • Above drainboard assembly 112 there is shown an article 127 that has been electrocoated in bath 113 and is now undergoing rinsing to wash off adhered paint particles which are removed from bath 113 with the coated article.
  • Article 127 is suspended from conveyor by a hanger 129 which is equipped with an insulator 131 and a contact plate or brush 133.
  • Catholyte separation unit 140 Positioned along the upper edge of coating tank 111 and positioned at the end of the tank where the articles to be coated enter the bath is a U-shaped catholyte separation unit 140.
  • Catholyte separation unit comprises a metal box 141 having a porous bottom 141-1 which may be of expanded metal, wire mesh, etc., and a separation membrane 143 which admits of the passage of water and water soluble materials such as amine, ammonia, KOH, LiOH, etc., therethrough.
  • the separator membrane 143 may be cloth, eg., saillQth., a water per'- meable plastic membrane, or other filter means of synthetic or natural materials.
  • the separation membrane 143 may be structured to provide an essentially complete barrier to the paint particles of bath 113 or it may admit of their limited passage to a degree such that the concentration of paint in catholyte separation unit 140 ranges up to 50, preferably below and more preferably below 1, percent of the corresponding concentration of the same in coating bath 113.
  • Catholyte separation unit 140 has outlet means on opposite sides of tank 111 in the form of conduits 160-1 and 160-2 through which liquid flows from the upper interior of catholyte separation unit 140 by gravity ow into collection units 161-1 and 161-2 which optionally are provided with lters 162. Collection units 161-1 and 161-2 are provided with drain conduits 163-1 and 163-2 which are operatively connected to pumps 145-1 and 145-2. Pumps 145-1 and 145-2 are operatively connected to conduits 149-1 and 149-2 through which liquid from catholyte separation unit 140 is passed by pumps 145-1 and 145-2 to shower heads 155 and 157 from whence the same is discharged upon article 127. In this embodiment, article 127 is thus rinsed while our drainboard assembly 112 and the rinse liquid drains back into coating bath 113.
  • Metal box 141 of catholyte separation unit 140 is in electrical connection with the tank 111. Thus, it becomes a part of the cathode of the cell and attracts cations through separation membrane 143, primarily those of the water soluble base employed to solubilize and/or disperse the acidic paint binder resin- Thus, within catholyte separation unit 140, there exists an aqueous dispersion that is paint solids poor and base rich relative to bath 113.
  • Catholyte separation units 40 and 140 are advantageously positioned near the point Where uncoated workpieces enter the coating bath since the greatest surge of current occurs before an electrically resistant lm builds upon the workpiece.
  • the term paint is meant to include pigment and/ or nely ground filler, the binder Without pigment and/or ller or having very little of the same, which can be tinted if desired.
  • the binder which is ultimately converted to a durable film can be all or virtually all that is used to form the film, or it can be vehicle for pigment and/or particulate iiller material.
  • aqueous dispersion comprising a synthetic polycarboxylic acid resin and water soluble base form a coating bath which is retained Within a bath container and is in contact with a relatively negative cathode, a relatively positive anode is immersed in said coating bath and a film of said paint is electrodeposited thereon, said anode is removed from said coating bath after electrodeposition of said film of paint and the resultant coated anode is sprayed with liquid to wash therefrom unattached paint particles thereon, the improvement which comprises separating from said bath within said bath container a liquid bath fraction which comprises water and water soluble base and a concentration of paint particles between 1 and 50% of the corresponding concentration in said bath by positioning within said bath a catholyte separation unit comprising an auxiliary cathode and a water permeable membrane through which a flow of paint particles is impeded thereby providing a differential flow through said membrane of paint particles on the one hand and water and water soluble base on the other and removing said
  • liquid bath fraction has a concentration of paint particles between 5 and 10% of the corresponding concentration within said coating bath.

Landscapes

  • 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)
  • Application Of Or Painting With Fluid Materials (AREA)
US00887949A 1969-12-24 1969-12-24 Catholyte rinse of electrocoat Expired - Lifetime US3730866A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US88794969A 1969-12-24 1969-12-24

Publications (1)

Publication Number Publication Date
US3730866A true US3730866A (en) 1973-05-01

Family

ID=25392197

Family Applications (1)

Application Number Title Priority Date Filing Date
US00887949A Expired - Lifetime US3730866A (en) 1969-12-24 1969-12-24 Catholyte rinse of electrocoat

Country Status (9)

Country Link
US (1) US3730866A (fr)
JP (1) JPS5016376B1 (fr)
BE (1) BE760778A (fr)
CA (1) CA947233A (fr)
DE (1) DE2063160C3 (fr)
DK (1) DK128943B (fr)
FR (1) FR2072044B1 (fr)
GB (1) GB1278385A (fr)
NL (1) NL7018810A (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3865706A (en) * 1970-07-22 1975-02-11 Ici Ltd Concentration and coating processes
US3945900A (en) * 1972-05-02 1976-03-23 Dorr-Oliver Incorporated Electro ultrafiltration process and apparatus
US3962059A (en) * 1974-01-08 1976-06-08 Miele & Cie. Process and device for electrophoretically plating metal parts
US4486284A (en) * 1981-11-30 1984-12-04 Toyota Jidosha Kabushiki Kaisha Method of electrodeposition coating and apparatus therefor
US4663014A (en) * 1986-01-02 1987-05-05 I. Jay Bassett Electrodeposition coating apparatus
US4755273A (en) * 1986-01-02 1988-07-05 Bassett I Jay Cover for coating tanks
USD303282S (en) 1986-01-02 1989-09-05 I. Jay Bassett Combined tank and cover assembly for use in electrodeposition coating operations
US5110440A (en) * 1988-02-16 1992-05-05 Elcoat Systems, Inc. Roll immersion system
ES2199645A1 (es) * 2000-08-29 2004-02-16 Honda Motor Co Ltd Dispositivo de pretratamiento de pintura y metodo de pretratamiento.

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002309396A (ja) * 2001-04-11 2002-10-23 Dainippon Printing Co Ltd 製版めっき方法

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1071458A (en) * 1965-05-31 1967-06-07 Pressed Steel Fisher Ltd A process for treating the effluent from plants for the electro-deposition of paint

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3865706A (en) * 1970-07-22 1975-02-11 Ici Ltd Concentration and coating processes
US3945900A (en) * 1972-05-02 1976-03-23 Dorr-Oliver Incorporated Electro ultrafiltration process and apparatus
US3962059A (en) * 1974-01-08 1976-06-08 Miele & Cie. Process and device for electrophoretically plating metal parts
US4486284A (en) * 1981-11-30 1984-12-04 Toyota Jidosha Kabushiki Kaisha Method of electrodeposition coating and apparatus therefor
US4663014A (en) * 1986-01-02 1987-05-05 I. Jay Bassett Electrodeposition coating apparatus
US4755273A (en) * 1986-01-02 1988-07-05 Bassett I Jay Cover for coating tanks
USD303282S (en) 1986-01-02 1989-09-05 I. Jay Bassett Combined tank and cover assembly for use in electrodeposition coating operations
US5110440A (en) * 1988-02-16 1992-05-05 Elcoat Systems, Inc. Roll immersion system
ES2199645A1 (es) * 2000-08-29 2004-02-16 Honda Motor Co Ltd Dispositivo de pretratamiento de pintura y metodo de pretratamiento.

Also Published As

Publication number Publication date
CA947233A (en) 1974-05-14
FR2072044A1 (fr) 1971-09-24
NL7018810A (fr) 1971-06-28
JPS5016376B1 (fr) 1975-06-12
BE760778A (fr) 1971-05-27
DK128943B (da) 1974-07-29
DE2063160B2 (de) 1979-04-19
FR2072044B1 (fr) 1974-03-01
DE2063160A1 (de) 1971-07-15
GB1278385A (en) 1972-06-21
DE2063160C3 (de) 1979-11-29

Similar Documents

Publication Publication Date Title
US3730866A (en) Catholyte rinse of electrocoat
US3304250A (en) Continuous electrocoating process utilizing electrodialysis to control the bath composition
US3200057A (en) Electrophoretic coating process
US4529492A (en) Process for the coating of hollow bodies open on one side
US3355374A (en) Method of electrocoating with variation of electrical inducement
US3404079A (en) Process for preparing an electrocoating bath
CN205774848U (zh) 一种电泳涂装设备及其管式阳极
US3616396A (en) Electrophoretic coating process
US3361658A (en) Method of electrophoretic surface coating
US4401051A (en) Process and an apparatus for extracting fine droplets of paint from paint-spraying units
Brewer Electrophoretic painting
GB972169A (fr)
US3898145A (en) Process for applying contrasting coatings to a workpiece
US3300400A (en) Electrocoating process with terminal showering step
US3630870A (en) Base concentration control in electrodeposition of paint
US3444064A (en) Method for improving operational stability of electrocoating bath
US3488273A (en) Electrodeposition method for design coating
US3855106A (en) Process for electrodeposition of paint
US3444063A (en) Method for improving operational stability of electrocoating bath
US3728242A (en) Continuous electrodeposition process
US3444065A (en) Method for electrodeposition of paint
CN210117413U (zh) 一种电泳涂装的硅烷预处理装置
US3650932A (en) Electro-flow coating method
US3725234A (en) Partial insulation of an electrodeposition tank
US3668100A (en) Electrophoretic coating of metal substrates using elevated pressures

Legal Events

Date Code Title Description
AS Assignment

Owner name: E. I. DU PONT DE NEMOURS AND COMPANY, DELAWARE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:FORD MOTOR COMPANY;REEL/FRAME:004660/0502

Effective date: 19861118

Owner name: E. I. DU PONT DE NEMOURS AND COMPANY, WILMINGTON,

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:FORD MOTOR COMPANY;REEL/FRAME:004660/0502

Effective date: 19861118