RU194202U1 - ELECTRODE BLOCK DEVICES FOR PLASMA TREATMENT OF A SURFACE OF AREA MATERIALS WITH A HIGH FREQUENCY CAPACITIVE DISCHARGE AT ATMOSPHERIC PRESSURE - Google Patents

Abstract

The invention relates to a plasma technology for processing areal (roll or sheet) materials, namely, devices for creating a high-frequency discharge plasma with a low specific power at atmospheric pressure. The electrode unit of a device for plasma surface treatment of areal materials with a high-frequency capacitive discharge at atmospheric pressure includes a discharge, grounded and ignition electrodes made with the possibility of connecting to a high-frequency generator, while the discharge electrode is made in the form of an extended part and is located opposite the grounded electrode, the ignition electrode is installed near the discharge electrode, while the discharge electrode is located along the grounded electrode, made long, the ignition electrode is made in the form of a flag having a beveled face, while the electrodes are fixed on the support and made with the possibility adjusting the sizes of the breakdown and discharge gaps by changing the gap between the discharge and grounded, as well as the discharge and ignition electrodes.

Description

The technical field to which the utility model relates.

This utility model relates to a plasma technology for processing materials, namely, devices for creating a high-frequency discharge plasma with a low specific power at atmospheric pressure, which can be used to process surfaces of areal materials, for example, when preparing a surface before further technological steps — gluing with other materials or the application of certain films and coatings, etc.

Processing can be carried out in order to increase the surface energy of the material, which leads to an increase in hydrophilicity and adhesion. Processing can be carried out on a wide range of materials, including glass, metal sheets and rolls, polymer films, non-woven materials and others. Glass processing can be performed, for example, before applying the polymer to create multilayer armored glasses, processing of polymeric materials - in the manufacture of snowboards before applying the adhesive layer, or when gluing multilayer compositions together, processing non-woven materials - to ensure a more saturated color of fabrics after dyeing, processing metals - for final cleaning of surfaces before bonding, sealing, painting, to remove organic contaminants on the surface before gluing, painting, sealing, etc. etc.

State of the art

The prior art technical solutions that provide plasma processing of various surfaces. Plasma treatment is a “dry” purification process that can replace environmentally harmful chemicals such as chlorinated hydrocarbons (trichlorethylene). Plasma is generated when a high-frequency field discharge is applied to a working gas: molecules dissociate into electrons, ions, highly reactive free radicals, short-wavelength ultraviolet photons, and other excited particles. When excited by a high energy discharge, these particles effectively clean the surface. If the atmosphere of the process contains an active gas, for example, oxygen, then along with mechanical bombardment, for example, of metal surfaces, chemical reactions also occur, leading to the removal of organic contaminants. Carbon compounds on the treated surface react with oxygen ions in the plasma to form a mixture of carbon dioxide and carbon monoxide, which is easily removed from the surface. Inert gases, such as argon, helium, nitrogen, can be used to effectively bombard the surface and mechanically remove small amounts of material.

The effect of plasma on the surface can extend to a depth of several microns, but usually <0.01 microns, so the plasma does not change the bulk properties of the material. As a rule, invisible but detectable organic contaminants can be removed using plasma, however, if the contamination is visible to the naked eye, preliminary mechanical / chemical cleaning will be required.

The prior art devices that provide plasma surface treatment of various materials. Among them are devices for spot processing - plasmatrons (RU 2477026, RU 2142679) and devices for processing areal materials using corona (RU 2306224, RU 1691129), barrier (RU 2471884) or high-frequency discharge (RU 2196394). In devices for spot processing, nozzles are used, inside which a discharge is generated using a capacitive or inductive electrode system. During operation of the device, the discharge is continuously blown out of the nozzle by a stream of inert gas to treat the surface of the material. The disadvantage of these types of systems is the point form factor that does not allow the processing of large rolled or sheet areal materials. In devices using a corona or barrier discharge as an electrode system, an extended grounded electrode is most often used, for example, made in the form of a shaft through which the processed material is drawn, opposite which there is either an active electrode (corona discharge) or an active electrode separated from grounded by a dielectric layer (barrier discharge). The disadvantage of these types of systems due to the use of an operating frequency that is different from high-frequency devices (up to 500 kHz versus 2, 4, 13.56, 27.12 MHz) is the increased power consumption, as well as the risk of damage to the processed material due to the chaotic formation of a large number of micro-breakdowns charging the surface of the material, and also the formation of a plume of low-temperature plasma, displaced along the surface of the material by a gas stream.

Closest to the claimed solution is the block of electrodes of the device for plasma surface treatment of areal materials by high-frequency capacitive discharge at atmospheric pressure, described in patent RU 2196394 (WO 02094455 A1). This device uses an extended discharge electrode, made in the form of a steel string, stretched using a tension spring between the inputs intended for connection to the power supply system. At the same time, execution allows the use of other options, such as a rod or metal tape, instead of a string. To ignite (initiate) the discharge, one or more pointed ignition electrodes are fixed on the string. During operation of the device, a discharge is initiated between the ignition electrode and the material, after which the discharge displaced by the supplied gas flow passes to the discharge electrode and continues along its movement, processing the surface of the material until it reaches the end of the electrode and breaks. After that, the discharge is again ignited at the beginning of the device, and the process is repeated again.

However, when working with this type of electrode system, the following disadvantages were identified: the discharge periodically experiences difficulties when switching from the ignition to the discharge electrode, it is localized near the ignition electrode, which leads to an increase in temperature, a change in its shape, and burnout. The cyclical nature of the process of ignition of the discharge, movement along the material, disruption of the discharge leads to insufficiently stable operation of the device, uneven processing of the material, and the inability to realize long continuous operation for at least one work shift - about 8 hours, which is necessary for using the device in real production conditions .

The technical problem solved by the claimed technical solution is to increase the duration of the continuous operation of the device for at least 16 hours, increase the smoothness of the transition of the discharge from the ignition to the grounded electrode, while maintaining the ability to configure the system for surface treatment of materials of various thicknesses.

Utility Model Disclosure

The technical result of the utility model is a significant increase in the duration of the continuous operation of the device due to the implementation of the block of electrodes, ensuring a smooth transition of the discharge from the ignition to the grounded electrode and stability of the discharge during the movement along the length of the material, while allowing the system to be configured to process the surface of materials of various thicknesses. The inventive block of electrodes is characterized by an extended service life, and a device using this block is characterized by uniform plasma treatment of the entire surface of the material, including due to the stability of the transition of the discharge from the ignition to the grounded electrode.

The technical result is achieved by using the proposed solution — the electrode block of a device for plasma surface treatment of areal materials with a high-frequency capacitive discharge at atmospheric pressure, including discharge, grounded, and ignition electrodes made with the possibility of connecting to a high-frequency generator, while the discharge electrode is made in the form of an extended part and located opposite the grounded electrode, the ignition electrode is installed near the discharge electrode, while m the discharge electrode is made extended and located along the grounded electrode, the ignition electrode is made in the form of a flag having a beveled face, while the electrodes are mounted on a support and made with the possibility of adjusting the sizes of the breakdown and discharge gaps by changing the gap between the discharge and grounded, as well as the discharge and firing electrodes.

The discharge electrode can be made with a L-shaped or T-shaped profile, one of the faces of which, directed towards the grounded electrode, is made with sharpening (tip). A grounded electrode can be made in the form of a metal plate, or stud, or rod. In this case, the grounded electrode is located under the discharge, coaxially with it. The discharge and ignition electrodes are preferably made of a thickness of 2-3 mm, the grounded electrode is made of a thickness of 2-5 mm and a width of 4-6 cm. The discharge and grounded electrodes, as a rule, are made of equal length, greater than the width of the processed material.

The electrode block is equipped with a dielectric discharge breaker located at the end of the discharge electrode. The discharge breaker is made in the form of a volumetric body with a smooth surface with a gradual increase in thickness in the direction of discharge movement, to ensure the creation of a smoothly increasing artificial obstacle to the discharge between the discharge and grounded electrodes in the final section of the discharge.

To realize the possibility of adjusting the sizes of the breakdown and discharge gaps by changing the gap between the discharge and grounded, as well as the discharge and ignition electrodes, these electrodes are equipped with appropriate means, namely: an extended hole is made in the grounded electrode from the side of the placement of the ignition electrode (when setting position of the ignition electrode vertically and horizontally); the ignition electrode is provided with at least one extended vertically oriented hole to enable adjustment of its vertical position (height); The ignition electrode is also provided with an axis to ensure its fastening on the support with the possibility of movement along the support and rotation about the axis, as well as displacement in a horizontal plane in the direction of movement of the discharge. These tools provide the possibility of reciprocating movement of the ignition electrode vertically and horizontally while maintaining its strictly vertical position coaxial with the direction of discharge propagation.

The flag is preferably made in the form of a triangular plate, for example, in the form of a right-angled triangle, while the beveled edge of the flag directed towards the discharge electrode has a serrated relief. The angle between the beveled edge of the flag and the horizontal plane of the grounded electrode is from 10 to 70 degrees.

Brief Description of the Drawings

The utility model is illustrated by drawings, where in FIG. 1 is a schematic representation of a device for plasma processing the surface of areal materials with a high-frequency capacitive discharge (UPR) containing the inventive electrode block; in FIG. 2 is a diagram of a block (system) of electrodes in two embodiments with different positions of the grounded and ignition electrodes relative to the discharge, depending on the thickness of the processed material; in FIG. 3 shows a three-dimensional image of a block of electrodes; in FIG. 4 - presents a part of the device with fastening elements and adjust the position of the electrodes of the block; in FIG. 5-7 show possible embodiments of the individual structural elements of the device — nozzle, frame holders, flag located in its own holder, respectively; in FIG. 8, 9 is an embodiment of a discharge tearing device for a discharge electrode of a plasma material processing device; in FIG. 10 is a block diagram of a plasma treatment plant for materials with additional equipment that implements a surface treatment process for materials.

The positions in the figures indicate: 1 - discharge electrode; 2 - material to be processed; 3 - grounded electrode; 4 - node adjusting the position of the ignition electrode vertically and horizontally; 5 - ignition electrode; 6 - tear; 7 - hole 7 in the grounded electrode 3 for moving and adjusting the ignition electrode 5 vertically and horizontally to adjust to a specific thickness of the processed material; 8 - longitudinal slots in the ignition electrode 5 to adjust its vertical position and fixation; 9 - axis for placing the flag (ignition electrode 5) for the implementation of its horizontal broadcast; 10 - support; 11 - metal studs bearings 10; 12 - the base plate of the support 10; 13 and 16 - holders of the lower frame and upper frame, respectively; 14 - flag holder; 15 - nozzle; 17 and 18 - the upper and lower frames, respectively; 19 - curtains.

The implementation of the invention

The inventive device is a block of electrodes installed in a device for plasma processing of areal materials (Fig. 1-8).

The electrode block includes a discharge electrode 1, a grounded electrode 3, an ignition electrode 5. The discharge electrode 1 can be made in the form of an extended part made of steel or duralumin with a L-shaped or T-shaped profile that minimizes the resistance of the electrode to the incoming air flow and is located along the grounded electrode 3. The thickness of the faces of the electrode 1 can be 2-3 mm, which provides significant heat capacity that prevents the rapid overheating of individual zones during discharge burning. The edge of the electrode 1, facing the grounded electrode 3, directly along which the discharge runs, is sharpened to facilitate the burning of the discharge. At the end of the anode there is a discharger of discharge 6, which serves to “tear” the discharge propagating along the processed material at the end of the path. The interrupter is made of a dielectric material, for example, fluoroplastic, in the form of a volumetric body with a smooth surface shape without pointed parts near the end of the discharge electrode with a smooth increase in thickness (in the form of a “wave”), for example, as shown in FIG. 8, 9. The presence of a tear and its shape provide the most smooth "removal" of the discharge from the discharge electrode, without disturbing the air flow. The presence of pointed elements near the end of the electrode and the violation of the gas flow leads to the localization of the discharge in one place and to stop processing the material.

The grounded electrode 3 can be made in the form of a sheet with a thickness of 2 to 5 mm made of steel or duralumin and a width of 4-6 cm. The grounded electrode 3 is placed coaxially under the discharge electrode 1 along the entire path of the discharge and surface treatment of the material. In the left part of the grounded electrode 3, a hole 7 is made for moving and adjusting the ignition electrode 5 vertically and horizontally to adjust to the specific thickness of the processed material. Grounded 3 and firing 5 electrodes are interconnected by a wire or brush to ensure good electrical contact.

The ignition electrode 5 is made in the form of a flag made of steel or duralumin. The thickness of the flag can be 2-3 mm, which provides significant heat capacity that prevents the rapid overheating of individual zones during discharge burning. The beveled edge of the flag, directed towards the discharge electrode, is made of a serrated relief (for example, in the form of a "ladder"). The location of the steps of the teeth on the verge of the ignition electrode increases the density of the electric field lines near the corners and thereby facilitates the ignition of the discharge, reducing the breakdown voltage. Steps can be performed in 1 mm increments. In the lower part of the ignition electrode, two longitudinal slots 8 are made for adjusting the vertical position and fixing it. The flag itself is placed on axis 9 for horizontal translation of the flag. As a device for horizontal broadcasting, a conventional threaded rod with a nut installed in the device body or a micrometer head (Fig. 7) can be used.

Essential in the claimed design is the implementation of the structural elements of the electrode block with the possibility of adjusting the sizes of the breakdown and discharge gaps, which is carried out using the node 4 adjust the position of the ignition electrode 5 vertically and horizontally. The node 4 also provides adjustment of the air gap between the edge of the discharge electrode 1 and the surface of the grounded electrode 3, for the possibility of processing materials of different thicknesses, which can be implemented by changing the position of the discharge electrode 1 vertically.

The inventive block of electrodes is placed in a device for plasma processing of materials (UPR), which may have a different design. One embodiment of this embodiment is shown in FIG. 1. UPR, in addition to the block of electrodes, contains two supports on which an extended frame is fixed (one, two or more), and the details of the node for adjusting the position of the ignition electrode vertically and horizontally (Fig. 4). The grounded electrode 3 of the electrode block is located on the lower frame, the discharge electrode 1 is fixed on the lower side of the upper frame, the ignition electrode 5 is fixed on the support by means of the axis 9. The electrodes are equipped with leads for connection to a power supply system.

The support, on the one hand (on the discharge side) contains four metal studs 11, on the opposite - two. The following details are sequentially mounted on the studs 11: base plates 12, which fix the position of the studs in space, then the holders of the lower frame 13 (Fig. 6) together with the flag holder 14 (Fig. 7), then the nozzle 15 (see Fig. 5) and, finally, the holder of the upper frame 16. The support 10 is configured to move the above parts along the studs during operation of the device relative to each other, which is especially important when changing processing modes.

The holder 14 of the flag (ignition electrode 5) is made in such a way that the flag can be moved back and forth while maintaining its strictly vertical position coaxial with the direction of discharge propagation (along discharge 1 and grounded 3 electrodes). The flag can be moved by rotating the washer plate. The overlay on the washer rotates the nut, the position of which on the axis of the frame is fixed, which drives the axis of the holder 9 and the flag attached to it. On the flag, longitudinal slots are made to enable smooth adjustment of the height of its protrusion above the grounded electrode (Fig. 3). Thus, it is possible to preserve the breakdown gap between the ignition and discharge electrodes when processing materials of various thicknesses.

In one embodiment, two frames 17 and 18 (Figs. 1, 4) are used in the UPR design, between which a nozzle 15 (Fig. 5) is installed above the base on the studs 11, which serves to introduce a directed air flow into the interelectrode gap. The design of the nozzle 15 is made in such a way as to realize the possibility of docking the fan, and on the other hand to focus the air flow into the interelectrode gap on the ignition 5 and discharge 1 electrodes. At the inlet, the nozzle 15 has a circular cross section to the size of the flexible gas supply flowing gas, and at the outlet, it is rectangular in size of the channel, inside which the discharge is burning.

The holders of the frame 13 and 16 (Fig. 6) consist of two identical parts - elements: it is installed on one frame, and the other is pressed by a screw clamp on the studs. To exclude horizontal coaxial movement of the device, the frame is fixed in the holders with the help of side screws.

Frames 17, 18 consist of 6 plexiglass plates. Two of these plates are slots for mounting the four remaining plates that act as stiffeners. After assembly, the plates are compressed with screws in two directions. The frame design practically does not involve sagging at almost a meter distance between the supports, which ensures the accuracy of setting the interelectrode distance at the level of 0.5 mm. A discharge electrode is attached to the lower edge of the upper frame, and a grounded electrode to the upper edge of the lower frame. The ignition electrode with axis 9 is located inside the lower frame. On the side surfaces of the frame holes are made for fastening the blinds 19.

The shutters 19 are made of plexiglass similar to the plates of the frame. Their function is to seal the interelectrode space, which was not involved in the processing of samples of various materials. The longitudinal slot of the blind allows you to adjust their vertical position, as well as block the unused part of the device for cases of processing narrow areal materials.

A device for plasma processing of materials with the claimed block of electrodes works as follows.

A discharge based on a capacitive RF atmospheric pressure discharge with an operating frequency of 13.56 MHz is initiated (ignited) at the edge of the processed material between the ignition and discharge electrodes, which are displaced by the air flow into the gap between the discharge and grounded electrodes and move along the surface of the processed material. At the end of its path, the discharge breaks off in the “tearing” region, and the process repeats again. The repetition rate is of the order of 10-20 Hz, depending on the air speed in the blowing system and the width of the processed material. The electrode block adjustment system allows you to set the discharge gap between the ignition and discharge electrodes for cases of processing materials of various thicknesses by horizontal and vertical reciprocating movements. The shape of the ignition electrode, however, provides easy ignition and the duration of its operation due to the smooth displacement of the discharge from the ignition electrode between the discharge and grounded electrodes, as well as significant heat capacity, which prevents the rapid overheating of individual zones during discharge burning.

An example of a concrete implementation of a utility model

A device was made for plasma activation of the surface of the material at atmospheric pressure with the following design parameters: width of the processed material 100 cm, step for adjusting the width of the material 10 cm, thickness range of the processed materials from 0.1 to 20 mm, operating frequency 13.56 MHz, atmospheric pressure, working gas - air, working power - about 400 W, continuous operation time - more than 24 hours.

The manufactured device was connected to a high-frequency generator, which was used as HFP GA-13.1-A7, the ATN-10 approval system of AKTAN VACUUM LLC and the air supply system. Atmospheric air was used as the working gas; the Erstvak evl33 / 28 vortex fan was used as a device for pumping / pumping gas (Fig. 10). The main electrode was made of an aluminum L-shaped profile, the ignition electrode was in the form of a flag with longitudinal slots for vertical adjustment of position.

The fabricated device for plasma activation of the surface of the material at atmospheric pressure was successfully tested on sheet glass. The contact wetting angles were measured depending on the number of passes through the material by a plasma device, as well as the degradation of the hydrophilicity effect depending on the time elapsed after treatment. The contact angle of wetting of sheet glass decreased from 40 ° without treatment to 7 ° after it was passed through an RF capacitive discharge in an air atmosphere.

A qualitative check of the effect of plasma treatment on changes in the adhesive properties of sheet glass was carried out. For this, a strip with a width of ~ 8 cm and a length of 45 cm was treated with a HF atmospheric discharge (at an operating frequency of 13.56 MHz, direct power of 400 W and 90 W reflected) using the manufactured prototype of the device for 10 seconds. As a result of these preliminary experiments, an increase in the hydrophilicity of glass after the processing exposure to plasma was proved. So, when spraying water on the surface of a sheet glass using a spray bottle, there was a sharp difference in the behavior of water droplets that fell on the treated and untreated surface. In the first case, water well wetted the glass surface with the formation of a thin transparent uniform surface film. On the contrary, in the untreated areas, individual drops of water accumulated that did not wet the surface, thus forming an opaque surface. After a qualitative confirmation of the improvement in the wettability of flat glass after plasma treatment, quantitative measurements of the effect of various treatment modes by atmospheric RF discharge on the adhesive properties of the material were carried out. To compare the effect of exposure duration on the activation efficiency of a sheet glass surface, the following tests were carried out. Measurements of the wetting angle of water were carried out on strips 8 cm wide and 45 cm long. A total of 4 strips. The first strip was treated only with alcohol. The second is alcohol and plasma for 10 seconds. Third with alcohol and plasma for 30 sec. Fourth with alcohol and plasma for 60 seconds.

To verify the degree of homogeneity of the processing of the material along the length of the device, zoning of the test samples was carried out before processing. Each strip was divided into 3 zones with a width of 8 cm and a length of 15 cm. The first zone was closer to the flag (the place where the discharge was initiated), the second farther, and the third was the most distant. After treatment, a drop of 15 μl was applied to each surface. The profile of this drop was photographed, and the contact angle of wetting was analyzed. The contact wetting angle was determined by averaging the “left” and “right” angles in the photo. The measurement results are shown in table 2.

According to the results of the tests, the successful application of the device for plasma processing of sheet glass was demonstrated in order to increase the hydrophilicity of its surface.

Thanks to the proposed solution, the device can process area materials continuously for more than 24 consecutive hours without visible damage to the electrode block to obtain high-quality plasma processing over the entire surface of the material.

Thus, the claimed device is characterized by the following advantages:

- significant heat capacity of the electrode block, which prevents the rapid overheating of individual zones during discharge burning and provides the possibility of long-term (more than 24 hours) continuous processing of materials without visible damage to the electrode block;

- the smooth transition of the discharge from the ignition region between the ignition and discharge electrodes further into the discharge gap between the discharge and the grounded electrode, which prevents the discharge from localizing in one place and prevents the heating and subsequent failure of individual structural elements;

- the stability of combustion and displacement of the discharge and, as a consequence, the high uniformity of the processing of the material due to the lack of localization of the discharge near the ignition electrode

- the stability of combustion and displacement of the discharge and, as a consequence, the high uniformity of the processing of the material, due to the provision of a stable disruption of the discharge near the end of the discharge electrode, which is associated with both the geometry and the shape and dielectric material of the tear;

- the presence of components that are lightweight, interchangeable, easy to manufacture (including using a 3D printer), reducing the overall dimensions of the entire device;

- the design of the electrode block in combination with other elements of the device provides sufficient accuracy for setting the interelectrode distance to ensure the operation of the device with materials of various thicknesses.

Claims (15)

1. The electrode block of the device for plasma surface treatment of areal materials with a high-frequency capacitive discharge at atmospheric pressure, including discharge, grounded and ignition electrodes made with the possibility of connecting to a high-frequency generator, while the discharge electrode is made in the form of an extended part and is located opposite the grounded electrode, ignition the electrode is installed near the discharge electrode, characterized in that the discharge electrode is located along the grounded electrode long, ignition electrode is made in the form of a flag having a beveled face, while the electrodes are configured to adjust the size of the breakdown and discharge gaps by changing the gap between the discharge and ground, as well as discharge and ignition electrodes. 2. The block according to claim 1, characterized in that the discharge electrode is made with a L-shaped or T-shaped profile, one of the faces of which is directed toward the grounded electrode, is made with sharpening. 3. The block according to claim 1, characterized in that the grounded electrode is made in the form of a metal plate or cylinder. 4. The block according to claim 1, characterized in that the discharge and ignition electrodes are made of 2-3 mm thick, the grounded electrode is made of 2-5 mm thick and 4-6 cm wide. 5. The unit according to claim 1, characterized in that it is equipped with a dielectric tear-off device located at the end of the discharge electrode. 6. The block according to p. 5, characterized in that the tear is made in the form of a three-dimensional body with a smooth surface, with a gradual increase in thickness in the direction of movement of the discharge. 7. The block according to claim 1, characterized in that the discharge and grounded electrodes are made of equal length, greater than the width of the processed material. 8. The block according to claim 1, characterized in that the grounded electrode is located subdischarge coaxially with it. 9. The block according to claim 1, characterized in that in the grounded electrode, on the side of the placement of the ignition electrode, an extended hole is made for moving the latter. 10. The block according to claim 1, characterized in that the ignition electrode is provided with at least one extended vertically oriented hole to enable adjustment of its vertical position. 11. The block according to claim 1, characterized in that the ignition electrode is configured to reciprocate horizontally while maintaining its strictly vertical position coaxial with the direction of discharge propagation. 12. The block according to claim 1, characterized in that the ignition electrode is provided with an axis to ensure its fastening on the support. 13. The block according to claim 1, characterized in that the flag is made in the form of a triangular plate, while the beveled edge of the flag directed towards the discharge electrode has a toothed relief. 14. The block according to claim 13, characterized in that the angle between the beveled edge of the flag and the horizontal plane of the grounded electrode is 10 ° to 70 °. 15. The block according to claim 1, characterized in that the electrodes are mounted on a support.

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