JP2022079886A - Plasma treatment apparatus - Google Patents

Abstract

To provide a plasma treatment apparatus capable of easily extending contact time of a powder to plasma longer than that of conventional ones.SOLUTION: A plasma treatment apparatus 1 includes: a plasma generation part 2 configured to apply a high-frequency voltage to a supplied gas to generate a plasma; a powder supply part 3 configured to hold a powder of a treatment target and supply the powder to an outside; a plasma treatment part 4 configured to make a plasma gas activated by the plasma supplied from the plasma generation part and the powder supplied from the powder supply part have contact with each other; and a powder separation part 5 configured to separate the powder and a gas composition. Each of the parts 2 to 5 is a separate body and connected to each other interposing a flow channel 8.SELECTED DRAWING: Figure 1

Description

The present invention relates to a plasma processing apparatus that performs plasma processing on powder.

The applicant of the present application has previously proposed the powder processing apparatus described in Patent Document 1. The purpose of this is to provide a powder hydrophilization treatment device and a treatment method capable of continuously charging and taking out powder at atmospheric pressure and freely changing the treatment time by plasma. The powder processing apparatus described in Patent Document 1 has a cylindrical substrate, an outer electrode and an inner electrode intermittently provided in the circumferential direction, a dielectric layer covering the outer electrode, and a high frequency voltage on the outer electrode and the inner electrode. It is provided with a high-frequency power source for applying the above-mentioned material, a powder transport means for inflowing the transport gas and powder into the inside of the cylindrical substrate, and a recovery means for recovering the surface-treated powder.

Here, in the powder processing apparatus described in Patent Document 1, the powder is flowed into a cylindrical apparatus provided with an outer electrode and an inner electrode for generating plasma to perform surface treatment. It was difficult to lengthen the time that the powder was in contact with the plasma in the device. This is a common problem even in the treatment using a gas activated by plasma (hereinafter referred to as "plasma gas").

Japanese Unexamined Patent Publication No. 2017-131803

Therefore, it is an object of the present invention to provide a plasma processing apparatus in which it is easy to extend the contact time of powder with plasma gas longer than before.

The present invention has a plasma generation unit that generates plasma by applying a high frequency voltage to the supplied gas, a powder supply unit that holds the powder to be processed and supplies the powder to the outside, and the plasma generation unit. It is provided with a plasma processing unit that brings the plasma gas activated by plasma supplied from the unit into contact with the powder supplied from the powder supply unit, and a powder separation unit that separates the powder and the gas component. , Each of the above parts is a separate body, and is a plasma processing apparatus connected to each other via a flow path.

According to this configuration, it is easy to set the time for contacting the powder with the plasma gas to the time required for the treatment by separating each part related to the plasma treatment.

Further, the plasma processing unit includes a mixing unit having a mixing space inside, and the plasma gas and the powder can form a circumferential flow in the mixing unit.

According to this configuration, in the mixing portion, the plasma gas and the powder form an orbital flow, so that the time for contacting the powder with the plasma gas can be set according to the degree of the orbit.

Further, the plasma processing unit includes each of a plasma gas inflow unit, a powder inflow unit, and a powder / plasma gas outflow unit that communicate with the mixing space and open to the outside, and the plasma gas inflow unit is the plasma. The powder inflow section is open to the side of the processing section, and the powder inflow section is radially outward from the mixing space of the mixing section, and is open above or below the plasma processing section. -The plasma gas outflow portion may be open upward or downward in the radial center of the plasma processing portion.

According to this configuration, it is easy to form a circular flow between the plasma gas and the powder, and a large distance can be taken from the part where the plasma gas and the powder flow in to the part where the powder flows out, so that the powder comes into contact with the plasma gas. You can set a long time to make it.

Further, the mixing space of the mixing portion has a circular cross section, and the plasma gas inflow portion is a tangent to the inner peripheral surface of the mixing portion that defines the circular edge portion in the mixing space. It can extend along the direction.

According to this configuration, since the plasma gas is allowed to flow in the tangential direction of the edge of the mixing space, it is possible to form a circumferential flow without reducing the speed.

Further, the powder / plasma gas outflow portion is tubular, and the end edge in the extension direction thereof is located above the bottom surface of the mixing portion or below the top surface of the mixing portion. Can be located in.

According to this configuration, the powder in the orbiting flow not only simply falls in the mixing space, but also moves upward once and overcomes the upper end edge of the tubular body to move from the powder / plasma gas outflow part to the outside of the plasma processing part. Leaked into. Alternatively, the powder in the orbiting flow not only simply rises in the mixing space, but also moves downward once and flows out from the powder / plasma gas outflow part to the outside of the plasma processing part by overcoming the lower end edge of the tube. .. Therefore, it is possible to prolong the time that the powder is on the orbiting flow in the mixed space.

Further, the plasma generating portion includes an external electrode located radially outward and an internal electrode located radially inward, and the internal electrode has a coil shape extending in the axial direction while rotating. can.

According to this configuration, plasma can be efficiently generated by forming the internal electrode into a coil shape.

In the present invention, it is possible to easily set the time for contacting the powder with the plasma gas to the time required for the treatment. Therefore, it is easy to lengthen the time for the powder to come into contact with the plasma gas longer than before.

It is a figure which shows schematic the whole structure of the plasma processing apparatus which concerns on one Embodiment of this invention. It is a radial sectional view which shows the generation part main body of the plasma generation part in the said plasma processing apparatus. FIG. 3 is a plan view showing a part of the plasma processing apparatus showing a plasma processing unit in a cross-sectional view. The plasma processing unit is shown, where FIG. 3A is a vertical cross-sectional view taken along the line IV-IV of FIG. 3, and FIG. 3B is a vertical cross-sectional view at the center in the radial direction.

Next, an embodiment of the present invention will be taken up and described. In addition, the expression of the direction in the following description is based on the direction of the state shown in each figure.

The plasma processing apparatus 1 of the present embodiment is configured as shown in FIG. 1, and performs a process of imparting properties such as hydrophilic treatment to powder or changing the originally possessed properties. Used for The plasma processing apparatus 1 of the present embodiment includes a plasma generation unit 2, a powder supply unit 3, a plasma processing unit 4, and a powder separation unit 5 as parts related to the present invention. Further, a dust collector 6 and a blower 7 are provided on the downstream side of the powder separation unit 5. The respective parts 2 to 5 are separate bodies and are connected to each other via the flow path 8. In this embodiment, each part 2 to 5 is connected by a pipe. The connection is made up of a portion forming a pre-process and a portion forming a post-process following the pre-process. By separating each part 2 to 5 related to the plasma treatment, it is easy to set the time for contacting the powder with the plasma gas to the time required for the treatment. Further, in the plasma processing apparatus 1 of the present embodiment, since the plasma generating unit 2 and the plasma processing unit 4 are separate bodies, the heat at the time of plasma generation is unlikely to affect the powder. Therefore, it is suitable for processing powders that are easily deteriorated by heat.

The plasma generation unit 2 is composed of a generation unit main body 21, a gas supply unit (gas tank) 22, and a high voltage power supply 23. Plasma is generated in the generating unit main body 21 by applying an alternating high frequency voltage supplied from the high voltage power supply 23 to the raw material gas supplied from the gas supply unit 22 to the generating unit main body 21.

As shown in FIG. 2, the generating portion main body 21 has a cylindrical shape, an inlet portion 211 for inflowing raw material gas is provided on one end side in the axial direction, and a raw material is provided on the other end side in the axial direction by plasma generated inside. An outlet portion 212 is provided to let out the plasma gas generated by activating the gas. As the raw material gas, for example, a rare gas such as argon or helium can be used. Depending on the purpose of the powder treatment, a gas other than the noble gas may be used entirely or additionally. The generating portion main body 21 has a double pipe structure in which the outer pipe 213 located radially outward and the inner pipe 214 located radially inward are arranged concentrically. The outer tube 213 and the inner tube 214 are formed of an insulator such as glass. The raw material gas is supplied to the space 21S between the outer pipe 213 and the inner pipe 214. That is, the raw material gas flows along the axial direction in the generating unit main body 21. A curved plate-shaped external electrode 215 is attached to the outer tube 213, and a coil-shaped internal electrode 216 extending in the axial direction while rotating is attached to the inner tube 214. Each of the electrodes 215 and 216 is made of a good conductor such as copper. A discharge is made between the external electrode 215 and the internal electrode 216. In the present embodiment, regarding the polarity of the internal electrode 216, the side indicated by "+" in FIG. 2 is the side connected to the high voltage power supply 23, and the side indicated by "-" is the ground side. The electric discharge is performed from the internal electrode 216 toward the external electrode 215. Due to this discharge, some molecules of the raw material gas passing through the space 21S between the outer tube 213 and the inner tube 214 are ionized and turned into plasma. In the generator main body 21 of the present embodiment, since the internal electrode 216 is coiled, the planar external electrode 215 and the linear internal electrode 216 face each other in the radial direction, so that both sides facing each other are opposed to each other. It is more likely to generate an electric discharge than a configuration in which the surfaces are planar or linear. Therefore, plasma can be generated efficiently. When the raw material gas is activated by this plasma, plasma gas is generated in the generation unit main body 21 of the plasma generation unit 2. This plasma gas flows out from the outlet portion 212 and is sent to the plasma processing portion 4 via the flow path 8.

The powder supply unit 3 includes a powder holding unit 31 which is a container for holding the powder to be processed by plasma treatment, and a feeder 32 which supplies the powder held in the powder holding unit 31 to the outside. Has been done. The powder is sent to the plasma processing unit 4 via the flow path 8.

The plasma processing unit 4 is a portion in which the plasma gas supplied from the plasma generation unit 2 via the flow path 8 is brought into contact with the powder supplied from the powder supply unit 3 also via the flow path 8. The plasma processing unit 4 includes a mixing unit 41 having a mixing space 41S inside. The mixing space 41S of the mixing portion 41 is a space having a substantially cylindrical shape flat in the vertical direction, that is, a space having a circular cross section. In the mixing portion 41, the plasma gas and the powder form a circumferential flow F. The circumferential flow F is a counterclockwise flow in a plan view in the present embodiment. In this way, in the mixing unit 41, the plasma gas and the powder form an orbital flow F, so that the time for bringing the powder into contact with the plasma gas can be set according to the degree of the orbit.

The plasma processing unit 4 includes each of a plasma gas inflow unit 42, a powder inflow unit 43, and a powder / plasma gas outflow unit 44 that communicate with the mixing space 41S and open to the outside. The plasma gas inflow section 42 is open to the side of the plasma processing section 4. As the plasma gas inflow portion 42 opened in the present embodiment, two places shown in the lower left and the upper right in FIG. 3 are used, but there may be three or more places. Incidentally, in the plasma processing unit 4 of the present embodiment, the plasma gas inflow unit 42 can be added up to four locations. A closing plug 45 is attached to the portion that is not opened. The portion 451 of the closed plug 45 facing the mixing space 41S has a curved surface corresponding to the inner peripheral surface 411 of the mixing portion 41, and has a shape that does not easily collide with the circumferential flow F formed in the mixing space 41S. It has become. Therefore, the unused plasma gas inflow portion 42 is less likely to adversely affect the circumferential flow F, as compared with simply attaching a lid to the flange of the unused plasma gas inflow portion 42.

The plasma gas inflow portion 42 extends along the tangential direction of the inner peripheral surface 411 of the mixing portion 41 whose radial center line defines a circular outer edge portion in the mixing space 41S. Since the plasma gas is allowed to flow in the tangential direction of the edge of the mixing space 41S, the plasma gas and the powder placed on the flowing plasma gas are less likely to collide with the internal structure of the mixing portion 41, and the plasma gas and Circular flow F can be formed in the mixing space 41S without causing a decrease in the speed of the powder. A nozzle portion 421 is attached to the plasma gas inflow portion 42. The nozzle portion 421 is provided from the outer end portion of the plasma gas inflow portion 42 to a position corresponding to the powder inflow portion 43. The diameter of the nozzle portion 421 is narrowed toward the inside, and the radial cross-sectional area is reduced. The nozzle portion 421 having this shape allows plasma gas to flow vigorously into the mixing space 41S.

The powder inflow section 43 opens above or below the plasma processing section 4 in the radial direction outward from the mixing space 41S of the mixing section 41. In the present embodiment, as shown by the solid line in FIG. 4, the powder inflow section 43 is provided with an opening above the plasma processing section 4, but it may also be provided with an opening below as shown by the alternate long and short dash line. can. The diameter center line of the powder inflow portion 43 coincides with the inner end portion of the nozzle portion 421 attached to the plasma gas inflow portion 42. Due to such a positional relationship, the inflowing powder can be merged with the plasma gas vigorously flowing into the mixing space 41S by the nozzle portion 421, so that the powder can be satisfactorily mixed with the plasma gas.

The powder / plasma gas outflow section 44 opens downward in the radial center of the plasma processing section 4. On the other hand, the plasma gas inflow portion 42 is located at the circular outer edge portion in the mixing space 41S. Therefore, it is easy to form a circumferential flow F between the plasma gas and the powder in the mixing space 41S, and the plasma gas and the powder flow out to the portions (plasma gas inflow portion 42, powder inflow portion 43) into which the plasma gas and the powder flow in. Since the distance to the portion (powder / plasma gas outflow portion 44) can be increased, the time for contacting the powder with the plasma gas can be set long. Further, since centrifugal force acts on the powder in the circumferential flow F, the powder is made to orbit the mixing space 41S while keeping the powder near the inner peripheral surface 11 of the mixing portion 41 which is a position outside the diameter of the mixing space 41S. You can continue. From this as well, the time for contacting the powder with the plasma gas can be set longer. Further, since it is easy to lengthen the time for contacting the powder with the plasma gas, the treatment for each powder in the circumferential flow F can be made uniform, so that the variation in the treatment can be suppressed.

Further, the powder / plasma gas outflow portion 44 is tubular, and as shown in FIGS. 4 (a) and 4 (b), the upper end edge 441, which is the end edge in the extension direction thereof, is from the bottom surface 412 of the mixing portion 41. Is also located above. That is, the upper end edge 441 is located inside the mixing portion 41. The amount of protrusion of the upper end edge 441 from the bottom surface 412 is set to 1 to 10 mm, but various protrusion amounts can be set according to the speed of the set circumferential flow F. By forming the powder / plasma gas outflow portion 44 in this way, the powder in the circumferential flow F not only simply falls in the mixing space 41S, but also moves upward once to form the tubular upper end edge 441. By overcoming it, it flows out from the powder / plasma gas outflow unit 44 to the outside of the plasma processing unit 4. Therefore, it is possible to prolong the time that the powder is on the circumferential flow F in the mixing space 41S. Incidentally, from the viewpoint of prolonging the time for the powder to come into contact with the plasma gas, the plasma gas described above is more than the configuration in which the upper end edge 441 of the powder / plasma gas outflow portion 44 protrudes from the bottom surface 412 of the mixing portion 41. It is more effective to have the inflow portion 42 in the tangential direction of the inner peripheral surface 411 of the mixing portion 41.

The powder / plasma gas outflow section 44 of the present embodiment is opened downward in the radial center of the plasma processing section 4, but on the contrary, it can be opened upward. In this case, the lower end edge, which is the end edge in the extension direction of the powder / plasma gas outflow portion 44, is located below the top surface of the mixing portion 41. Whether the outflow direction is downward or upward can be selected, for example, by the specific gravity of the powder, for example, from the viewpoint that the time during which the powder is on the circumferential flow F in the mixed space 41S can be lengthened.

Further, in the plasma processing unit 4, the plasma gas and the powder are continuously supplied to the processing unit. Therefore, unlike batch processing, plasma processing can be performed efficiently.

The powder separation unit 5 is a portion that separates the plasma-treated powder and the gas component contained in the plasma gas. The powder separation unit 5 separates the powder and the gas component up and down, for example, by forming a cyclone flow inside. Then, a dust collector 6 for collecting the powder remaining in the gas component flowing out from the powder separation unit 5 is connected to the powder separation unit 5. The gas component leaving the dust collector 6 is discharged to the outside of the device by the blower 7.

According to the plasma processing apparatus 1 of the present embodiment configured as described above, it is easy to set the time for bringing the powder into contact with the plasma gas to the time required for the processing. Therefore, it is easy to lengthen the time for the powder to come into contact with the plasma gas longer than before.

Further, according to the plasma processing apparatus 1 of the present embodiment, by separating each part related to the plasma processing, the following effects can be obtained. That is, it is possible to prevent the electrode from generating heat due to the increase in electrical resistance due to the adhesion of powder to the electrode. Further, since the powder contact surface inside the plasma processing device 1 can be changed to a free material (for example, fluororesin or ceramics), contamination due to wear of the electrode material or the powder contact surface can be prevented. Further, the degree of freedom in design is high with respect to the adjustment of the plasma gas flow rate, the shape of the plasma generating unit 2, and the shape of the plasma processing unit 4.

In addition, the inventor compares the plasma processing apparatus 1 of the present embodiment with the plasma processing apparatus of the type in which the plasma processing unit and the powder separation unit are integrated, and the supply amount of the raw material gas (argon) is the same. Then, when the treatment of powders (two types of acrylic resin and carbon black) was tried with the same voltage applied to the plasma generating part, the water contact angle of the treated powders became smaller for both powders. Therefore, it was confirmed that the hydrophilicity of the powder could be improved as compared with the plasma processing device to be compared.

Although the present invention has been described above with reference to one embodiment of the present invention, the present invention is not limited to each of the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

1 Plasma processing device 2 Plasma generating part 21 Generating part main body 21S Generating part Main body space 211 Inlet part 212 Outlet part 213 Outer pipe 214 Inner pipe 215 External electrode 216 Internal electrode 22 Gas supply part 23 High voltage power supply 3 Powder supply part 31 Powder holding part 32 Feeder 4 Plasma processing part 41 Mixing part 411 Inner peripheral surface of mixing part 412 Bottom surface of mixing part 41S Mixing space 42 Plasma gas inflow part 421 Nozzle part 441 Top edge 43 Powder inflow part 44 Powder plasma Gas outflow part 5 Powder separation part 6 Dust collector 7 Blower 8 Flow path F Circular flow

Claims (6)

A plasma generator that generates plasma by applying a high frequency voltage to the supplied gas,
A powder supply unit that holds the powder to be processed and supplies the powder to the outside,
A plasma processing unit that brings the plasma gas activated by the plasma supplied from the plasma generation unit into contact with the powder supplied from the powder supply unit.
Equipped with a powder separation unit that separates powder and gas components,
A plasma processing device in which each of the above parts is separated and connected to each other via a flow path. The plasma processing unit includes a mixing unit having a mixing space inside.
The plasma processing apparatus according to claim 1, wherein in the mixing section, the plasma gas and the powder form a circumferential flow. The plasma processing unit includes each of a plasma gas inflow unit, a powder inflow unit, and a powder / plasma gas outflow unit that communicate with the mixing space and open to the outside.
The plasma gas inflow portion is open to the side of the plasma processing portion.
The powder inflow portion is open above or below the plasma processing portion in the radial direction outward from the mixing space of the mixing portion.
The plasma processing apparatus according to claim 2, wherein the powder / plasma gas outflow portion opens upward or downward in the radial center of the plasma processing portion. The mixed space of the mixing portion is a space having a circular cross section.
The plasma processing apparatus according to claim 3, wherein the plasma gas inflow portion extends along the tangential direction of the inner peripheral surface of the mixing portion that defines the circular edge portion in the mixing space. The powder / plasma gas outflow portion is tubular, and the end edge in the extension direction thereof is located above the bottom surface of the mixing portion or below the top surface of the mixing portion. The plasma processing apparatus according to claim 3 or 4. The plasma generating portion includes an external electrode located radially outward and an internal electrode located radially inward.
The plasma processing apparatus according to any one of claims 1 to 5, wherein the internal electrode has a coil shape extending in the axial direction while rotating.

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