EP2050506A1 - Pulverbeschichtungssprühvorrichtung - Google Patents

Pulverbeschichtungssprühvorrichtung Download PDF

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Publication number
EP2050506A1
EP2050506A1 EP07118895A EP07118895A EP2050506A1 EP 2050506 A1 EP2050506 A1 EP 2050506A1 EP 07118895 A EP07118895 A EP 07118895A EP 07118895 A EP07118895 A EP 07118895A EP 2050506 A1 EP2050506 A1 EP 2050506A1
Authority
EP
European Patent Office
Prior art keywords
powder
electrode
nozzle
powder coating
container
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Withdrawn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
EP07118895A
Other languages
English (en)
French (fr)
Inventor
Amir Keller
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.)
Trivium Aluminium Packaging Netherlands BV
Original Assignee
Boxal Netherlands BV
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 Boxal Netherlands BV filed Critical Boxal Netherlands BV
Priority to EP07118895A priority Critical patent/EP2050506A1/de
Priority to PCT/EP2008/064121 priority patent/WO2009050298A1/en
Publication of EP2050506A1 publication Critical patent/EP2050506A1/de
Withdrawn legal-status Critical Current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
    • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
    • B05B5/03—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying
    • B05B5/032—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying for spraying particulate materials
    • 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

Definitions

  • the present invention is directed to a powder coating spray apparatus and to a method of spray application of a powder coating. More particularly, the invention is directed to a spray gun and application method that are particularly suitable for coating the inside walls of hollow metal products, such as aluminium containers, e.g., aluminium aerosol containers.
  • the two main powder coating application technologies are tribostatic spray application and electrostatic spray application.
  • tribostatic spray application powder particles are charged by causing them to move along a specially designed and shaped surface. The frictionally charged particles will then be attracted to, and deposited onto the substrate.
  • the extent of frictional charging is governed by the volume of powder delivered onto the charging surface and the speed it moves across the surface, both of which can be controlled by the tribostatic gun operator.
  • a high voltage generator is used to charge an electrode at the tip of the powder gun. This creates an electrostatic field (or corona) between the gun and the substrate. Gas molecules in the air pick up electrons emitted from the corona. This negative charge is, in turn, transferred to the powder particles as they are propelled from the gun head towards the substrate.
  • the target substrate is held at an electrical potential relative to the electrode, typically ground, and the charged powder particles are attracted to and readily adhere to the substrate.
  • An electrostatic spraying apparatus typically includes a spray nozzle through which powder is ejected toward a target surface or object to be coated with the powder.
  • Powder is fed to the spray apparatus from a powder supply, typically a powder feed hopper that may include a fluidized powder bed.
  • the powder is fluidized in the hopper by a flow of air through the floor of the hopper.
  • One or more powder pumps may be used to pump the fluidized powder from the hopper to one or more spray guns through a corresponding number of powder feed hoses.
  • a typical electrostatic corona charging powder spray gun includes an electrical power input cable, a powder hose and may further include an air line for purge air, all connectable to the back end of the spray gun.
  • a specific powder coating spray gun using corona charging is disclosed in US 6,796,519 .
  • Aerosol cans are generally made from an aluminium-based alloy with an aluminium content of 99.7% in weight or more.
  • the alloy used is usually shaped into slugs of predetermined diameter. A strip is obtained by continuous casting, and then hot followed by cold rolling. The slugs are then cut out and thermally annealed. Then the aerosol cans are manufactured from the slugs, e.g., by means of a cold impact extrusion step. A layer of lacquer or varnish is then applied to the inside of the can.
  • This layer of lacquer for example a phenolic epoxy resin, is preferably applied by spraying followed by polymerization, at a temperature comprised between 200° C and 250° C for a period of time of less than 10 minutes.
  • the can may then be subjected to an external printing step designed to form patterns on the outside wall of the can.
  • Liquid coating materials are nowadays used for the internal coating of aerosol cans. These materials give rise to numerous environmental problems as a result of their solvent content. This also applies to cases where aqueous coating materials are employed. It is therefore increasingly being attempted to replace these coating materials by solvent-free substitutes, in particular powder coatings.
  • the object of the invention is to provide a powder coating apparatus and a coating method which is particularly suitable for coating the interior of a can or container, such as an aluminium aerosol container, in an automated production cycle.
  • a powder coating spray apparatus or spray gun comprising:
  • the powder channel surrounding the electrode can for example be an annular channel around the electrode, or it can for example comprise at least three, four or more powder channels equidistantially arranged in a circular array around the electrode.
  • the powder channels can be spiraled along the electrode. It has been found that more turbulence in the powder channels reduces coagulation of the powder coating material particles and the pofing effect.
  • the channels can for instance be made of flexible hoses or the like.
  • a diffuser element located at a distance downstream the nozzle.
  • use of the word "downstream” refers the flow direction of the powder coating material during spraying.
  • the diffuser can for instance have a perforated wall provided with a pattern of equally distributed apertures, the wall being disposed under right angles with the flow direction of the sprayed powder coating material. Particularly good effects are obtained if the perforated wall of the diffuser element is concave.
  • the object of the present invention is also achieved with a method of coating the interior of a container having a longitudinal axis characterized in that a powder coating material is sprayed evenly distributed as a spraying cone via a spray nozzle which is moved along the longitudinal axis of the container. While the nozzle is moved along the longitudinal axis of the container, a coating of even thickness is obtained.
  • the container and the spray nozzle do not need to be rotated relative to each other.
  • the spraying cone of powder coating material can be formed around a central electrode with a tip end arranged centrally in the nozzle. This way, the electrode does not disturb the formation of a spray cone. Moreover, since the nozzle, and thus the electrode, is moved along the longitudinal axis of the container, the distance between the substrate and the electrode is substantially equal and a corona is obtained showing rotational symmetry.
  • a short pulse of pressurized air is blown through the powder channels before the powder coating is sprayed. This purges and cleans the powder channels from coating material left from an earlier cycle. Moreover, it creates a corona of pre-ionized air already before the powder is sprayed, unexpectedly resulting in a high surface quality of the applied coating.
  • the method according to the invention is particularly suitable for aluminium containers, such as an aerosol container having a cylindrical or mainly cylindrical shape, e.g. a shouldered and/or waisted cylinder.
  • FIG 1 shows a powder coating spraying apparatus 1 comprising a spray gun 2 connected to a feed hopper 3 via a powder supply line 4.
  • a trigger sensor 5 serves to detect the presence of an aluminium aerosol container 6 when the container is in line with the longitudinal axis of the spray gun 2.
  • An earthing member 7 is brought into contact with the aluminium container.
  • the spray gun 2, the container 6, the trigger sensor 5 and the earthing member 7 are shown in cross section in Figure 2 .
  • dotted lines A indicate the outline of a spray cone of sprayed powder coating material.
  • the spray gun 2 comprises a body 21 encasing a charger element (see Figure 2 ) connected to a power supply 8.
  • An insert pipe 23 is inserted in a bore 24 running through the body 21.
  • the insert pipe 23 is connected to the powder feed line 4.
  • the insert pipe 23 ends in a splitter 25 splitting the powder supply channel into four powder supply channels 26, as can be seen in more detail in Figure 3 .
  • the charger element 22 comprises an extension 27 inclined towards the splitter 25 where it contacts an electrode 28.
  • a lance 29 is connected to the body 21 in line with the bore 23.
  • the electrode 28 is disposed coaxially in the lance 29 along the lances longitudinal axis.
  • the four powder supply channels 26 are flexible hoses spiraled along the electrode 28.
  • the outer ends of the electrode 29 and the four powder channels 26 are hold in a nozzle element 30, shown in detail in Figures 4 and 5.
  • the nozzle element 30 comprises a cylindrical skirt 31 closely fitting into the lance 29, and a plug part 32 comprising a central opening 33 and four spray openings 34 arranged around the central opening 33 at even distance from each other.
  • the spray openings 34 are shouldered to receive the ends of the powder channel lines 26 in a clamping manner.
  • a diffuser element 35 comprising a first cylindrical section 36, closely fitting into lance 29, and a second cylindrical section 37 with a smaller diameter closely fitting into skirt 31 of the nozzle element 30.
  • the first cylindrical section 36 is capped with a concave end wall 38 with a central opening 39 and diffuser openings 40.
  • the electrode 28 passes through the central opening 33 in the nozzle element 30 and the central opening 39 in the diffuser element 35 and projects out of the open end of the lance 29.
  • the diffuser openings 40 have a smaller diameter than the outlet openings of the powder channels. However, the total summed-up through-flow of all diffuser openings 40 should not be less than the total through-flow via the outlet openings of the powder supply channels 26.
  • a pneumatic control 50 is used to activate a first valve 51 to pass a pulse of pressurized air via the powder feed hopper 3 and feed line 4 to the spray gun 2, exactly dosing the required amount of powder coating material needed to coat the interior of the aerosol container 6. Powder coating material is transported only during spraying and no continuous re-circulation is required..
  • a pulse of clean air is blown for about 10 - 20 milliseconds via an additional air feed line 52 through the spray gun 2 by activating a second valve 53 by means of pneumatic control 50.
  • a pulse of clean air is blown for about 10 - 20 milliseconds via an additional air feed line 52 through the spray gun 2 by activating a second valve 53 by means of pneumatic control 50.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
EP07118895A 2007-10-19 2007-10-19 Pulverbeschichtungssprühvorrichtung Withdrawn EP2050506A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP07118895A EP2050506A1 (de) 2007-10-19 2007-10-19 Pulverbeschichtungssprühvorrichtung
PCT/EP2008/064121 WO2009050298A1 (en) 2007-10-19 2008-10-20 Powder coating spraying apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP07118895A EP2050506A1 (de) 2007-10-19 2007-10-19 Pulverbeschichtungssprühvorrichtung

Publications (1)

Publication Number Publication Date
EP2050506A1 true EP2050506A1 (de) 2009-04-22

Family

ID=39143239

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07118895A Withdrawn EP2050506A1 (de) 2007-10-19 2007-10-19 Pulverbeschichtungssprühvorrichtung

Country Status (2)

Country Link
EP (1) EP2050506A1 (de)
WO (1) WO2009050298A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010125282A1 (fr) * 2009-04-29 2010-11-04 Arkema France Dispositif et procede de pulverisation

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9027506B2 (en) 2011-05-02 2015-05-12 Nordson Corporation Dense phase powder coating system for containers

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4381081A (en) * 1978-12-20 1983-04-26 Nordson Corporation Nozzle assembly for spray coating systems
US4613075A (en) * 1983-07-15 1986-09-23 Imperial Chemical Industries Plc Electrostatic spraying
EP0553052A1 (de) * 1992-01-22 1993-07-28 José De Fusco Lupo Pistole zur elektrostatischen Zerstäubung von Pulvern verschiedener Farben und Eigenschaften
US5850976A (en) * 1997-10-23 1998-12-22 The Eastwood Company Powder coating application gun and method for using the same
DE19838278A1 (de) * 1998-08-22 2000-02-24 Itw Gema Ag Sprühbeschichtungsvorrichtung für Beschichtungspulver
EP1084759A2 (de) * 1999-09-16 2001-03-21 Nordson Corporation Pulversprühpistole

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE711312A (de) * 1968-02-26 1968-07-01
NL187729C (nl) * 1980-01-04 1992-01-02 Icab Ind Coating Ab Elektrostatische poederspuit.
US5468295A (en) * 1993-12-17 1995-11-21 Flame-Spray Industries, Inc. Apparatus and method for thermal spray coating interior surfaces
US6076742A (en) * 1999-03-11 2000-06-20 Sulzer Metco (Us) Inc. Arc thermal spray gun extension with conical spray
US7112350B1 (en) * 2003-07-14 2006-09-26 Duct Seal Systems, Inc. Method for applying liner to air duct

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4381081A (en) * 1978-12-20 1983-04-26 Nordson Corporation Nozzle assembly for spray coating systems
US4613075A (en) * 1983-07-15 1986-09-23 Imperial Chemical Industries Plc Electrostatic spraying
EP0553052A1 (de) * 1992-01-22 1993-07-28 José De Fusco Lupo Pistole zur elektrostatischen Zerstäubung von Pulvern verschiedener Farben und Eigenschaften
US5850976A (en) * 1997-10-23 1998-12-22 The Eastwood Company Powder coating application gun and method for using the same
DE19838278A1 (de) * 1998-08-22 2000-02-24 Itw Gema Ag Sprühbeschichtungsvorrichtung für Beschichtungspulver
EP1084759A2 (de) * 1999-09-16 2001-03-21 Nordson Corporation Pulversprühpistole

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010125282A1 (fr) * 2009-04-29 2010-11-04 Arkema France Dispositif et procede de pulverisation
FR2944980A1 (fr) * 2009-04-29 2010-11-05 Arkema France Dispositif et procede de pulverisation

Also Published As

Publication number Publication date
WO2009050298A1 (en) 2009-04-23

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