FR2838559A1 - Ionizing chamber, with two high voltage electrodes forming an ionizing zone, has electrical insulation for the gas feeds on entry into the chamber to protect the operatives - Google Patents

Abstract

The ionizer has an air treatment chamber (2) fitted with at least two electrodes (21,23), defining an ionizing zone (24) between them. One electrode (23) has an electrical connection to a high voltage electricity generator (4) giving 10-20 kV. A gas feed (26) opens into the ionizing zone, linked to an external controlled gas supply (6). The gas feed connections (30) are electrically insulated between the gas supply and the chamber.

Description

command (3) of at least one control member (1).

  The present invention relates to a dielectric barrier electric discharge ionization device comprising a gas transport circuit to

near the ionization zone.

  Such devices, commonly called "<corona treatment devices", are used for example for the surface treatment of substrates in

  scrolling, such as plastic films or metal sheets.

  In the context of these applications, they make it possible to modify the

  surface energy and adhesion characteristics of the substrates treated during

  their passage through an ionization zone.

  In general, these devices include a treatment enclosure in which are located two electrodes arranged in parallel and

  spaced an interval of, for example, between 0.5 and 5 mm.

  One of the electrodes, designated as the reference electrode, is connected to a reference potential such as earth, and the other, designated as the high ten electrode.

  sion, is connected to an alternating high voltage generator.

  At least any one of the two electrodes is covered with a

dielectric material.

  In operation, voltages of the order of 10 to 20 kV are applied

  from the generator to the high voltage electrode.

  It therefore appears between the electrodes, an electric field of high intensity which makes it possible to ionize the atmosphere of the interval separating the two electro des. In order to improve the functioning of these installations, provision is made in a conventional manner for means of controlling the atmosphere of the ionization zone. These means consist of elements external to the treatment enclosure and elements internal to the enclosure, connectable to each other and outlet

  singing in or near the ionization zone.

  The set of elements used is conventionally con, cu from conductive materials and the distance separating these elements and the electrodes can be very small, so that all of the control means

  the atmosphere can be brought to a high floating or not potential.

  The manipulation of these means, and in particular of elements external to the treatment enclosure, therefore presents a significant risk for the

  personnel using such a device.

  The object of the present invention is to eliminate this risk.

  The subject of the invention is therefore an ionization device by electrical discharge with a dielectric barrier of an ionization zone, the device comprising a treatment enclosure which comprises at least two electrodes defining between them the ionization zone, namely a reference electrode electrically connectable to a reference potential, and a high voltage electrode electrically connectable to a high voltage electric generator, at least one of the electrodes being covered with a dielectric material, the device further comprising means for gas supply to the ionization zone which includes pipes and injection nozzles leading to the vicinity of this zone, the gas supply means being connectable to a gas supply and equation outside the enclosure, characterized in that the gas supply means comprise, inside the enclosure eVou at the crossing from the wall thereof, gas transport means, electrically insulating in order to allow, for the transport of gas, an electrically insulated connection between the gas supply and regulating device external to

The enclosure and the ionization zone.

  According to other characteristics: - said insulating means of transport comprise electrically insulating connections, arranged on said pipes; - the insulating means of transport comprise an electrically insulating, intermediate gas storage enclosure, adapted to be connected to the pipes and to the injection nozzles; - said means of transport comprise electrically insulating conduits; the injection nozzles are terminated by sleeves made of electrically insulating materials and in particular resistant to high temperatures; - Said electrically insulating gas transport means, are made of a PTFE-based material; - Said high voltage electrode consists of a gas diffusion enclosure comprising a slot opening onto the ionization zone; - It includes an intermediate gas storage enclosure, connected upstream to the pipes and downstream to the gas diffusion enclosure by means of pipes; and - said gas transport means are impermeable to the gases used. The invention also relates to an installation for the treatment of a substrate comprising an ionization device by electric discharge with a dielectric barrier, connected to a high-voltage generator and to a gas supply and equation device, and comprising in in addition to means for driving the substrate through the said enclosure, character ized in that it led it

  ionization device, is a device as defined above.

  The invention will be better understood on reading the description which will

  follow, given only by way of example and made with reference to the accompanying drawings, in which: - Fig.1 is a diagram representing an installation equipped according to the invention and intended for the treatment of a substrate; - Fig.2 shows an embodiment of the invention; and

  - Fig.3 shows another embodiment of the invention.

  In Figure 1, there is shown an installation for treatment

  of a continuous substrate and equipped with a device according to the invention.

  This device is described connected to the other elements of the installation. However, all the connections are adapted to be removable and the device

  can be considered as a stand-alone element.

  It includes a treatment enclosure 2 connected to an electrical generator

  plate 4 suitable for generating alternating high voltage signals.

  The installation also includes a device 6 for supplying and

  gas regulation connected to the treatment chamber 2, for the transport of gas.

  Advantageously, the installation also includes means 7 for connection connected to the enclosure 2 and composed, for example, of fan and vacuum systems, making it possible to improve the control of the atmosphere.

in enclosure 2.

  The installation further comprises rollers 8 for guiding a continuous substrate 10, adapted to allow the substrate 10 to travel, constituted for example by a continuous synthetic or natural polymer film, through

the treatment chamber 2.

  The treatment enclosure 2 comprises a reference electrode 21 of cylindrical shape, rotatable about its longitudinal axis, covered with a dielectric material 22 and electrically connected to a reference potential such as earth, and a high voltage electrode 23 blade-like extending parallel

  ment to the axis of the electrode 21 and electrically connected to the generator 4.

  The electrodes 21 and 23 define between them an ionization zone 24. Typically, the ionization zone 24 is 0.5 to 5 mm high in order to

  allow the passage of the substrate 10 between the electrodes 21 and 23.

  By virtue of its shape, the electrode 21 participates in the running movement of the substrate 10 obtained by means of drive devices not shown. Thus, after having been deflected by a first roller 8, the substrate 10 enters the enclosure 2 through an opening 25 in the latter. The substrate 10 is then wound around the upper part of the electrode 21 by crossing the ionization zone 24 and leaves the enclosure 2 through the opening 25 before being at

  again deflected by a second roller 8.

  The device is also connected to a gas supply device 6

and regulation.

  For this purpose, the enclosure 2 also comprises means 26 for supplying gas connected to the device 6 for gas supply and for equation and outlet

  edge in contact with or near the high voltage electrode 23.

  The gas supply means 26 are composed of pipes 27 leading to injection nozzles 28 or injectors, located in contact or at

  proximity to the high voltage electrode 23.

  In operation, the gas supply and regulation device 6 makes it possible, thanks to the supply means 26, to control the parameters of

  the atmosphere of the ionization zone 24.

  In particular, these means 6 and 26 make it possible, for example, to control the nature, the flow rate, the temperature and the pressure of the gases brought into the

ionization zone 24.

  According to the embodiment of the invention shown in FIG. 1, the gas supply means 26 comprise, at the crossing of the wall of the enclosure 2, electrically insulating connections 30, impermeable to the gases used and connecting pipes 27 and device 6 for supply and regulation

in gas.

  For example, these fittings 30 are made of a plastic material

  high density, such as a PTFE (polytetrafluoroethylene) material.

  Thus, in operation, the high voltage electrode 23 is charged at a high potential and, due to their proximity and their conductivity, the nozzles

  injection 28 and pipes 27 are also at high potential.

  However, the connections 30 make it possible to electrically isolate the supply means 26 inside the enclosure 2 of the device 6 for supplying and equating gas outside this enclosure 2, while preserving the tightness of the

gas supply circuit.

  Thus, the device 6 for supplying and equating gas does not have

  no risk for a user outside enclosure 2.

  In Figure 2, there is shown a second embodiment of the invention. In this figure, the pipes 27 are directly connected to the

  gas supply and equation device 6.

  At their downstream end, the pipes 27 are connected to one in

  girdle 31 intermediate gas storage.

  According to the invention, this enclosure 31 is composed of a material im

  permeable to the gases used and electrically insulating.

  The injection nozzles 28 are directly connected to this enclosure

storage 31.

  The device comprises a plurality of injection nozzles 28 distributed along the high voltage electrode 23, so as to ensure homo diffusion

  gas gene in the ionization zone 24.

  In operation, the high voltage electrode 23 is charged at a high potential, so that the injection nozzles 28 are also charged at

high potential.

  However, thanks to the presence of the storage enclosure 31 made of an electrically insulating material, the pipes 27 are at neutral potential and do not transmit any voltage to the device 6 for supplying gas and

  outside the enclosure 2.

  In Figure 3, there is shown a third embodiment of the invention. As in the embodiment described above, the pipes 27 are directly connected upstream to the gas supply and regulation device 6 and, downstream, to an intermediate enclosure 32

gas storage.

  In this embodiment, the high voltage electrode 23 is constituted by a gas diffusion enclosure 33 comprising on its underside, a slot 34 parallel to its longitudinal axis and to the axis of the electrode 21, this slot

  leading to the ionization zone 24.

  Typically, this slot is of a width of the order of 1 mm.

  The enclosure 33 of the electrode 23 is connected to the gas storage enclosure 32 by a plurality of conduits 35 distributed along the enclosures 32 and 33,

  so as to ensure a homogeneous diffusion of the gas in the enclosure 33.

  In this embodiment, the enclosure 33 is made of a conductive material, while the conduits 35 are made of a material im

  permeable to the gases used and electrically insulating.

  Thus, the enclosure 33 is charged at a high potential and fulfills the function of high voltage electrode while allowing the diffusion of the gas through

slot 34.

  However, due to the presence of electrically insulating conduits 35, whatever the material used for the production of the intermediate storage enclosure 32 and the conduits 27, these are at neutral potential and do not transmit to the voltage at of gas supply device 6 and

  outside the enclosure 2.

  In another embodiment (not shown), the injection nozzles are terminated by sleeves made of a material impermeable to the gases used and electrically insulating and remain at neutral potential. The nozzles then do not transmit any voltage to the other elements constituting the

gas supply means.

  Advantageously, these sleeves 34 are also made of a material suitable for withstanding high temperatures, due to a possible rise in temperature in the ionization zone during operation.

of the device.

  In other embodiments, the electrodes and the means

  scrolling drive are arranged differently.

  Likewise, the treated substrate can be a solid or porous substrate, continuous or discontinuous, and can be transported by a conveyor through the

ionization zone.

  Furthermore, the means of transporting electrically insulating gases may be permeable to the gases used in order to participate in the control of

The atmosphere in enclosure 2.

  Finally, the dielectric material can be placed indifferently on one

either of the electrodes.

Claims (10)

  1. Device (2) for ionization by electrical discharge with dielectric barrier   plate of an ionization zone (24), the device comprising a treatment enclosure   (2) which comprises at least two electrodes (21, 23) defining between them the ionization zone (24), namely a reference electrode (21) electrically connectable to a reference potential, and a high voltage electrode ( 23) electrically connectable to a high voltage electric generator (4), at least one of the electrodes being covered with a dielectric material (22), the device further comprising means (26) for supplying gas into the area ionization (24) which include pipes (27) and injection nozzles (28) leading into this zone (24), the means (26) for supplying gas being connectable to a supply device and gas regulation (6) outside the enclosure (2), characterized in that the means (26) for supplying gas comprise, inside the enclosure (2) and / or at the crossing of the wall thereof, means (30; 31;   35) for transporting electrically insulating gases in order to allow, for the trans-   gas port, an electrically isolated connection between the gas supply and regulation device (6) outside the enclosure (2) and the area ionization (24).   2. Device according to claim 1, characterized in that said means (26) of insulating transport comprise fittings (30) electrically   insulators arranged on said pipes (27).   3. Device according to any one of the preceding claims,   characterized in that the insulating transport means (26) include a   electrically insulating intermediate gas storage enclosure (31), suitable   to be connected to the pipes (27) and the injection nozzles (28).   4. Device according to any one of the preceding claims,   characterized in that said means of transport (26) includes   electrically insulating pipes (35).   5. Device according to any one of the preceding claims,   characterized in that the injection nozzles are terminated by sleeves made of electrically insulating materials and in particular resistant to high temperatures.   6. Device according to any one of the preceding claims,   characterized in that said means (30; 31; 35) for transporting electric   only insulators, are made of a PTFE-based material.   7. Device according to any one of the preceding claims,   character ized in that the said high voltage electrode (23) consists of a gas diffusion enclosure (33) comprising a slot (34) leading to the ionization zone (24).   8. Device according to claim 7, characterized in that it comprises an enclosure (32) intermediate gas storage, connected upstream to the pipes (27) and downstream to the gas diffusion enclosure (33) by   through the conduits (27).   9. Device according to any one of the preceding claims,   characterized in that said gas transport means (30; 31; 35) are im- permeable to the gases used.   10. Installation for the treatment of a substrate (10) comprising a positive device for ionization by electric discharge with a dielectric barrier (2), connected to a high voltage generator (4) and to a device (6) for supplying and of gas equation, and further comprising means (8) for driving the substrate (10) in movement through said enclosure (2), characterized in that said device   ionization device is a device according to any one of the preceding claims.