SU839585A2 - Apparatus for applying powdered polymeric material in electrostatic field - Google Patents

Description

(54) DEVICE FOR APPLYING POWDER-SHAPED POLYMER MATERIAL IN AN ELECTROSTATIC FIELD

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The invention relates to the production of polymer coatings in an electrostatic field and can be used in the electrical industry in the production of laminated plastics, varnished fabrics, etc.

According to the main author. St. No. 492122 discloses a device for applying a powdered polymer material in an electrostatic field, containing its powder fluidization chamber with an electrode device placed inside, through which a substrate is passed, a drying chamber, tempering and receiving mechanisms, and a charging device made in the form of two rolls, the surface of which is lined with fluoroplastic, than the electrode device is made in the form of a two-row system of electrodes arranged in parallel rows with alternating, it is polarized in height e each p yes and in a parallel p control 1

However, the known device does not provide a sufficient degree of charging of the particles of the applied powder, due to the separation of particles by size over the height of the chamber and limits the plant capacity.

The purpose of the invention is to increase plant productivity.

The goal is achieved by the fact that the electrode device is equipped with additional two-row electrode systems connected to independent power sources of various voltages.

The drawing schematically shows the proposed device.

A device for applying powdered polymer material in a high-voltage electrostatic field contains a fluidization chamber of powder 1 with a porous bottom 2, which separates it from the pressurization chamber 3. Inside the fluidization chamber there is an electrode device which consists of two-row systems of electrodes 4, 5 and 6, connected respectively to self-contained power sources 7, 8 and 9.

Claims (1)

Each electrode system of the electrode device contains four electrodes that are connected in two electrically connected circuits, one of which is connected to the negative pole of the power source and the other is grounded, while the opposite electrodes in the system create their own electric fields of the same intensity but in the opposite direction. In addition, electrodes in all systems of the electrode device. they are connected in such a way that their polarity alternates in a row, and each electrode has a polarity opposite to that of the opposite electrode, while the distance between the rows is approximately two times smaller than the distance of the electrodes in the row. Each electrode has three elements. However, the distance between them is chosen so as to exclude their mutual screening. A charging device 10 is located at the entrance to the pressurization chamber, which consists of two rollers (not shown in the drawing) lined with fluoroplastic. Inside the pre-liquefaction chamber there is a sealing device 11, which, in addition to sealing the SUBSTRATE (roll material) 12, also has an electrifying effect, since the inner surfaces of the device are lined with fluoroplastic. At the exit from the fluidization chamber, an essential chamber 13 is placed. To move the web material, tempering 14 and receiving 15 mechanisms with a roller 16 are installed. The device operates as follows. Powder from a polymeric material is poured into the fluidization chamber 1, and compressed air (gas) is fed into the supercharging chamber 3, due to the presence of a porous bottom 2 and air pressure, the powder in the chamber goes into a fluidized state. However, due to the presence of different particle sizes of the powder, the fluidized bed has a non-uniform dispersion in height, i.e., larger heavy particles are concentrated in the lower part of the layer, and smaller light particles are concentrated in the upper part. On the other hand, the charge received by an aerosol particle is proportional to the square of its radius and the intensity of the external FIELD. This leads to the fact that larger particles in a given electric field acquire a much larger charge than smaller ones. In this connection, under the action of an external field, the deposition of larger particles occurs much more intensively than small ones. Thus, in order to charge larger particles, a lower voltage is required, which is achieved by applying a lower voltage from the power source 7 to the electrode system 4. The electrode system 5 from the power source 8 is supplied with a higher voltage, and the electrode system 6 from the power source 9 is supplied with a voltage even higher, since the smallest particles of the applied powder are in the zone of action of this system and their concentration is low. Such a design of the electrode device in the measurement of fluidization creates at least three independent electric fields, the strengths of which are selected depending on the dispersion composition in the zone of action of each electrode system. This circumstance and the presence of three electrode elements in each electrode leads to an increase in the number of ions, which causes a more intense charge of the particles of the applied powder and leads to the fact that the drift velocity and, consequently, the deposition rate of the particles on the substrate increases. The latter makes it possible to increase the speed of movement of the substrate and thereby increase the productivity of the device, as well as drastically reduce the number of non-settling powder particles carried to the atmosphere, i.e., reduce the unproductive consumption of the applied material. Next, the dielectric substrate 12, for example, fiberglass, with the tempering mechanism 14 is pulled through the rollers of the charging device 10, the sealing device 11, the camera 1 with the electrode systems 4, 5 and b housed therein, the actual camera 13, the roller 16 to the receiving mechanism 15. When the substrate 12 moves, as a result of its rubbing against the surface of the rollers of the charging device 10 and the walls of the sealing device 11, which are lined with fluoroplastic, static charges of positive polarity appear on both sides of it. A positively charged substrate, when passing between rows of electrode systems 4, 5, and 6 of an electrode device, crosses the power lines of the electric fields created by these systems. The alternation of the polarities of the electrodes provides a two-sided application of particle particles to the substrate. The substrate coated with the polymer powder is passed through the drying chamber 13, where the deposited powder particles melt on the substrate, and then into the receiving mechanism 15 through the roller 16. The proposed device allows to increase the productivity of the process in the production of laminated varnished plastic, etc. Formula of the invention for applying a powdered polymer material in an electrostatic field according to the author. St. No. 492122, characterized in that, in order to increase