WO2018179344A1

WO2018179344A1 - Plasma surface treatment method and plasma surface treatment apparatus

Info

Publication number: WO2018179344A1
Application number: PCT/JP2017/013619
Authority: WO
Inventors: 賢二高島
Original assignee: 株式会社イーツーラボ
Priority date: 2017-03-31
Filing date: 2017-03-31
Publication date: 2018-10-04
Also published as: JP6944634B2; JPWO2018179344A1

Abstract

[Problem] To provide surface treatment technology capable of performing surface treatment on an object consisting of aggregates of small individual pieces in a manner that is thorough, reliable, and low-cost. [Solution] A spray port 33 for ionized treatment gas is disposed in a tubular passage 21 into which treatment object W is dropped. Spraying the ionized treatment gas into the tubular passage 21 from the spray port 33 forms, in the tubular passage 21, a treatment gas flow orthogonal to the direction in which the tubular passage is disposed. The treatment object W is then introduced through an opening on the upper end of the tubular passage 21, and surface treatment is performed on the treatment object W by bringing the treatment object W into contact with the treatment gas as the treatment object W is falling through the tubular passage 21.

Description

Plasma surface treatment method and plasma surface treatment apparatus

The present invention relates to a plasma surface treatment method and a plasma surface treatment apparatus, and more particularly, to a surface treatment technique for an object to be processed which is an aggregate of small individuals.

In order to improve various performances such as hydrophilicity, dispersibility, adhesion, etc. of the object to be treated, the surface treatment is performed on the object to be treated.

As a surface treatment method, a method of modifying the surface of the object to be treated by immersing the object to be treated in a chemical solution such as electrolytically oxidized water or ozone water (for example, see Patent Document 1), ultraviolet light is applied to the object to be treated. A method for modifying the surface of the object to be processed by irradiation (see, for example, Patent Document 2), and a method for modifying the surface of the object to be processed by spraying a processing gas that has been turned into plasma on the object to be processed (for example, Patent Document 3) is known.

By the way, in recent years, the recycling of carbon fibers has attracted attention. In the recycling of carbon fiber, chopped fiber or milled fiber is generated by finely cutting or crushing used carbon fiber. These chopped fibers and milled fibers are mainly used as a reinforcing material for synthetic resin (base material) or a conductivity imparting material. That is, when a synthetic resin molded product is manufactured, desired performance (for example, desired strength and conductivity) is imparted to the synthetic resin molded product by mixing the chopped fiber or milled fiber with the synthetic resin. The When mixing a chopped fiber or a milled fiber with a base material, it is necessary to improve the affinity and dispersibility with the base material, and therefore surface treatment of the chopped fiber or milled fiber is performed in advance.

Also, in fields other than carbon fiber recycling, for example, when mixing micro-sized materials such as powders and carbon nanotubes with other materials such as liquids and synthetic resins, these materials are mixed before mixing. Surface treatment is performed on the surface.

Japanese Unexamined Patent Publication No. 2016-141913 JP-A-8-188961 JP 2014-220056 A

However, there are the following problems in the surface treatment that uses an aggregate in which individual individuals are small, such as chopped fibers, powder particles, and carbon nanotubes, and improvement has been desired.

(1) The method of immersing the object to be treated in the chemical solution requires a step of drying the object to be treated, and the number of steps required for the surface treatment increases, while the cost of discarding the used chemical solution is high. There is a problem that the labor and cost for the surface treatment are increased.

(2) The method of irradiating the object to be processed with ultraviolet rays may cause leakage of ultraviolet rays when the object to be processed is folded or when the object to be processed has complicated irregularities. That is, there is a possibility that a part where the surface treatment is not performed or a part where the surface treatment is insufficient is generated without being irradiated with ultraviolet rays.

(3) In the method of spraying the plasma-ized processing gas, the target object may be scattered or dissipated by the spraying of the processing gas. That is, due to the scattering of the object to be processed, the contact between the object to be processed and the processing gas becomes insufficient, and the surface treatment may not be sufficiently performed.

The present invention has been made in view of such problems, and the object of the present invention is to ensure that the surface to be processed consisting of a collection of small individuals is surely leak-free and at a low cost. An object of the present invention is to provide a plasma surface treatment method and a plasma surface treatment apparatus capable of performing treatment.

In order to achieve the above object, a plasma surface treatment method according to the present invention is directed to a tubular passage through which an object to be treated is dropped, and a process gas jet port is disposed along the arrangement direction of the tubular passage. By injecting a plasma processing gas into the tubular passage from the processing gas jet port, a flow of the processing gas is formed in the tubular passage in a direction intersecting the arrangement direction of the tubular passage. The object to be treated is introduced into the tubular passage from the upper end opening of the passage, and the treatment gas is brought into contact with the object to be treated in the process of passing the object to be treated through the tubular passage to perform surface treatment on the object to be treated. It is characterized by performing.

And as a preferred embodiment thereof, the object to be treated is a chopped fiber.

Further, as another preferred embodiment, the object to be processed is a granular material.

On the other hand, a plasma surface treatment apparatus according to the present invention includes a tubular body having a tubular passage for dropping an object to be treated, and a jet of processing gas that faces the tubular passage and extends in the direction in which the tubular passage is disposed. The plasma generating processing gas ejected from the jet outlet forms a processing gas flow in the tubular passage in a direction crossing the arrangement direction of the tubular passage. It is characterized by having a structure to make it.

As a preferred embodiment thereof, the plasma generator is composed of two plasma generators arranged to face each other with the tubular body interposed therebetween, and the outlets of the plasma generators are mutually connected from the facing position. It is characterized by being shifted in position.

As another preferred embodiment, a suction device is provided on the lower end opening side of the tubular body for sucking out the object to be treated that stays in the tubular passage out of the tubular passage.

Furthermore, as another preferred embodiment, a recovery device for recovering the object to be processed that has passed through the tubular passage is provided on the lower end opening side of the tubular body.

According to the present invention, the object to be treated is brought into contact with the plasmaized treatment gas in the tubular passage and is subjected to the surface treatment, so that the object to be treated is not scattered or dissipated during the surface treatment. Moreover, since the surface treatment is completed in the tubular passage, the surface treatment can be performed with few steps, and the surface treatment can be realized at a low cost.

In addition, the object to be processed introduced into the tubular passage falls while swirling in the tubular passage on the flow of the processing gas in the direction intersecting with the arrangement direction of the tubular passage. Can be taken longer. Therefore, the contact with the processing gas can be sufficiently achieved, and the surface treatment to the object to be processed can be reliably performed. Further, surface treatment without leakage can be performed even on an object to be processed having complicated irregularities.

It is front sectional drawing which showed typically the structure of the plasma surface treatment apparatus which concerns on this invention. It is the plane sectional view showing typically the structure of the plasma surface treatment apparatus. It is a disassembled perspective view of the tubular body and plasma generator in the plasma surface treatment apparatus. It is sectional drawing which showed typically an example of schematic structure of the plasma generator in the plasma surface treatment apparatus. FIG. 5A is a cross-sectional view schematically showing another embodiment of the electrode structure of the plasma generator in the plasma surface treatment apparatus, and FIG. 5A shows a case where the voltage application electrode is configured in a semicircular cross section, 5 (b) shows a case where the parallel plate method is used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2 show an example of a plasma surface treatment apparatus 1 according to the present invention. The plasma surface treatment apparatus 1 shown in these drawings is a surface treatment apparatus in which a collection of small individuals is an object to be processed W.

Here, as an aggregate of small individuals to be processed W, an aggregate having an individual size of several mm or less, an aggregate of several μm or less, an aggregate of several nm or less, or a few mm to several For example, an aggregate in which individuals of nm are mixed. Specifically, a granular material, a chopped fiber, a milled fiber, a carbon nanotube, a pigment etc. are illustrated, for example.

Further, examples of the type of surface treatment performed by the plasma surface treatment apparatus 1 include hydrophilicity improvement, dispersibility improvement, adhesion improvement, water repellency, surface reduction, organic substance removal, coating, and the like.

The plasma surface treatment apparatus 1 includes a tubular body 2 having a tubular passage 21 for dropping an object to be processed W, and a plasma generator 3 for supplying a plasma-treated processing gas to the tubular passage 21 as main parts, and a tubular passage. A workpiece receiving portion 4 that accommodates the workpiece W to be introduced into 21, a suction device 5 that sucks out the workpiece W staying in the tubular passage 21, and a workpiece that has passed through the tubular passage 21. And a collection device 6 for collecting the body W.

The tubular body 2 is composed of an elongated hollow tubular member having a substantially annular cross section. As shown in FIG. 1, the tubular body 2 forms a tubular passage 21 by arranging elongated cavities therein in the vertical direction. That is, the tubular body 2 is arranged vertically so that the opening at one end is on the top and the opening at the other end is on the bottom.

The side surface of the tubular body 2 is provided with a gas introduction hole 22 for introducing the processing gas ejected from the plasma generator 3 into the tubular passage 21 (see FIG. 3). In the present embodiment, the gas introduction hole 22 is formed of a slit-like long hole along the arrangement direction (vertical direction) of the tubular passage 21 and is formed through the side surface of the tubular body 2. .

Here, the gas introduction hole 22 has a shape of the outlet 33 of the plasma generator 3 so that the processing gas injected from the outlet 33 of the processing gas in the plasma generator 3 can be introduced into the tubular passage 21 without leakage. It is formed according to. That is, in this embodiment, since the jet outlet 33 of the plasma generator 3 is comprised by a slit-shaped long hole, the gas introduction hole 22 is also comprised by the slit-shaped long hole according to this shape. In the present embodiment, the case where the gas introduction hole 22 is constituted by a single slit-like long hole has been shown. However, the gas introduction hole 22 may be formed of, for example, a plurality of slits along the arrangement direction of the tubular passage 21. It is also possible to configure by arranging the fine pores in a line.

Further, the gas introduction hole 22 allows the processing gas introduced into the tubular passage 21 to flow in a direction intersecting the arrangement direction of the tubular passage 21 in the tubular passage 21 (specifically, an arrow in FIG. 2). As shown by the symbol A, the processing gas introduced into the tubular passage 21 is arranged so as to form a spiral flow). That is, the position of the gas introduction hole 22 is determined so that the injection direction of the processing gas introduced from the plasma generator 3 (see arrow B in FIG. 2) does not pass through the center of the tubular passage 21 (see FIG. 2), the processing gas introduced into the tubular passage 21 forms a spiral flow in the tubular passage 21.

In addition, in this embodiment, since the two

plasma generators

3 and 3 are employ | adopted as the plasma generator 3 and the opposing arrangement | positioning on both sides of the tubular body 2, the gas in the tubular body 2 is accompanied with this. One introduction hole 22 is provided for each ejection port 33 of each plasma generator 3.

In addition, since the plasma processing gas is introduced into the tubular passage 21, the tubular body 2 is preferably made of an insulating material such as glass or ceramics, but has conductivity such as metal. It is also possible to form the tubular body 2 with a material.

As shown in FIG. 3 and FIG. 4, the plasma generator 3 includes a box-shaped casing 31 that contains plasma generating means for converting a processing gas into plasma by dielectric barrier discharge. The bottom plate 32 is provided with an ejection port 33 for ejecting plasma-treated processing gas.

The plasma generating means has a structure in which a voltage application electrode and a ground electrode are arranged opposite to each other with a certain interval, and one or both electrode facing surfaces of these electrodes are covered with a dielectric such as ceramics. Therefore, when a high frequency voltage is applied to the voltage application electrode, a dielectric barrier discharge is generated between both electrodes. The plasma generator 3 supplies the processing gas between the electrodes during the discharge to turn the processing gas into plasma (plasma activation), and injects the plasma-ized processing gas to the outside from the ejection port 33. Yes.

Here, an example of the electrode structure of the plasma generator 3 will be briefly described with reference to FIGS. 4 and 5.
In the plasma generator 3 shown in the present embodiment, as shown in FIG. 4, the voltage application electrode 34 has a structure including a cylindrical outer peripheral surface 34a. And the voltage application electrode 34 of such a structure is arrange | positioned over the full length of the longitudinal direction (up-down direction of FIG. 3) of the housing | casing 31. As shown in FIG. The outer peripheral surface 34a of the voltage application electrode 34 is covered with a solid dielectric such as ceramics.

On the other hand, the ground electrode has a structure in which the bottom plate 32 of the casing 31 also serves as an electrode. Specifically, a concave groove 32 a having a circular arc shape corresponding to the outer peripheral surface 34 a of the voltage application electrode 34 is formed on the surface of the bottom plate 32 on the voltage application electrode side, and the concave groove 32 a is formed on the voltage application electrode 34. The electrode facing surface is configured. In addition, a slit-like long hole serving as the processing gas jet port 33 is provided in the deepest portion of the concave groove 32 a corresponding to the entire length of the voltage application electrode 34.

The plasma generator 3 configured in this manner is arranged so that the processing gas jet port 33 faces the tubular passage 21 of the tubular body 2 and along the arrangement direction of the tubular passage 21. That is, the jet outlet 33 of the plasma generator 3 and the gas introduction hole 22 of the tubular body 2 are arranged with their positions aligned.

FIG. 5 shows another example of the electrode structure of the plasma generator 3.
The plasma generator 3 shown in FIG. 5A is obtained by modifying the electrode structure of the plasma generator shown in FIG. The plasma generator 3 shown in FIG. 5A is configured by accommodating a voltage applying electrode 34 having a semicircular cross section in a hollow cylindrical solid dielectric 35. A solid dielectric 35 is also disposed on the inner peripheral surface of the concave groove 32a of the bottom plate 32 that also serves as a ground electrode.

The plasma generator 3 shown in FIG. 5B shows a case where a so-called parallel plate type electrode structure is adopted as the electrode structure. In the plasma generator 3 shown in FIG. 5B, the electrode facing surfaces of the voltage application electrode 34 and the ground electrode 36 are both flat, and a dielectric barrier discharge is generated between the

electrodes

34 and 36. It is composed. In the electrode structure shown in FIG. 5B, each of the

electrodes

34 and 36 is configured to have a thin plate shape on the bottom plate 32 side, thereby preventing capacitive coupling with the bottom plate 32.

Incidentally, in the plasma generator 3 shown in FIGS. 4 and 5, both have an electromagnetic shield structure in which the bottom plate 32 of the casing 31 is electrically grounded. This is to prevent the workpiece W from being damaged by the high frequency power applied to the voltage application electrode 34. In particular, if the object to be processed W is made of a material having a large electrical resistance value such as metal, metal oxide, or carbon fiber (chopped fiber), the object to be processed W generates heat unless an electromagnetic shield structure is used. It will be damaged.

In this embodiment, two

plasma generators

3 and 3 are used as the plasma generator 3 constituting the plasma surface treatment apparatus 1, and each

plasma generator

3 and 3 sandwiches the tubular body 2. Opposed. Specifically, as shown in FIG. 2, the

jet outlets

33 and 33 of the

respective plasma generators

3 and 3 are arranged so as to be shifted from each other so as to be processed in the tubular passage 21. A gas vortex is formed. That is, the processing gas injected from each of the

jet outlets

33, 33 is disposed in the tubular passage 21 by disposing the

jet outlets

33, 33 of the

respective plasma generators

3, 3 so as to be shifted from each other. It will act to form a vortex-like flow inside.

The object-to-be-processed container 4 is a box-shaped container that accommodates the object to be processed W to be introduced into the tubular passage 21, and the object to be processed W accommodated in the object-to-be-processed container 4 It is introduced into the tubular passage 21 from the upper end opening. Specifically, the bottom of the object-to-be-treated accommodation portion 4 and the upper end opening of the tubular passage 21 are connected via a tubular communication passage 41, and the object-to-be-treated accommodation portion 4 is connected via the communication passage 41. A workpiece W is introduced into the tubular passage 21.

In the introduction of the object to be processed W into the tubular passage 21, in order to prevent the object to be processed W from being introduced into the tubular passage 21 in a lump state, in this embodiment, the object to be processed W is A mechanism for dispersing, for example, a net-like sieve 42 such as a wire mesh is disposed in the communication passage 41, and the workpiece W is introduced into the tubular passage 21 while being dispersed by the sieve 42.

The suction device 5 is a device for sucking out the workpiece W staying in the tubular passage 21 to the outside of the tubular passage 21, and is provided on the lower end opening side of the tubular passage 21. Specifically, the suction device 5 includes a device main body 51, a recovery cover 52 that surrounds the lower end opening of the tubular passage 21, and a suction path 53 that connects the recovery cover 52 and the device main body 51. In addition, by sucking out the air in the recovery cover 52 by suction by the apparatus main body 51, the recovery of the workpiece W by the recovery device 6 is assisted. In addition, the backflow of the to-be-processed object W to the to-be-processed object accommodating part 4 side is also prevented by the suction by this suction device 5.

The collection device 6 is a device for collecting the workpiece W that has passed through the tubular passage 21, and is provided at the lower end opening of the tubular passage 21. In the present embodiment, the collection device 6 includes a bag-like filter 61 that surrounds the lower end opening of the tubular passage 21, and the workpiece W sucked out from the tubular passage 21 is collected by the filter 61. It has become.

1 shows a case where three filters are used as the filter 61 in the plasma surface treatment apparatus 1 shown in FIG. In the illustrated example, the workpieces W having different sizes are selected and filtered using three filters 61. That is, the large object W is collected by the inner filter 61 and the small object W is collected by the outer filter 61.

In the present embodiment, the case where the filter 61 is composed of three sheets is shown, but the number of filters can be changed as appropriate. In addition, the sizes of the workpieces W to be filtered by the filters 61 can be the same.

Next, the surface treatment procedure of the workpiece W using the plasma surface treatment apparatus 1 configured as described above will be described.

(1) In the surface treatment of the workpiece W, first, the

plasma generators

3 and 3 and the suction device 5 are operated.

By the operation of the plasma generator 3, the process gas converted into plasma is ejected from the ejection port 33 of the plasma generator 3 and is introduced into the tubular passage 21. Thereby, in the tubular channel | path 21, as mentioned above, the spiral flow of the direction which cross | intersects the arrangement | positioning direction of the tubular channel | path 21 by process gas is formed. The processing gas used at this time is appropriately selected according to the material of the workpiece W, the content of the surface treatment to be performed, and the like. For example, a mixed gas of nitrogen (N ₂ ) gas and air (CDA: Clean Dry Air) is used as the processing gas.

Further, by the operation of the suction device 5, the processing gas or the like in the tubular passage 21 is sucked to the lower end side of the tubular passage 21. Thereby, the flow of the processing gas in the tubular passage 21 is sucked out of the tubular passage 21 as a downward spiral flow as shown by an arrow A in FIG. The suction by the suction device 5 causes the processing gas in the tubular passage 21 to be gently sucked out of the tubular passage 21. That is, the flow rate sucked by the suction device 5 is made slightly larger than the flow rate of the processing gas introduced from the

plasma generators

3 and 3 into the tubular passage 21.

(2) Next, the target object W is introduced into the tubular passage 21 from the target object accommodating portion 4.

The object to be processed W introduced into the tubular passage 21 from the object-to-be-processed container 4 is introduced into the tubular passage 21 while being dispersed by the sieve 42. The workpiece W introduced into the tubular passage 21 falls in the tubular passage 21 due to gravity. At this time, the process gas in the tubular passage 21 causes the treatment object W to flow in the tubular passage 21 more than when it falls freely. The flight time is extended.

That is, since the workpiece W of the plasma surface treatment apparatus 1 according to the present invention is a collection of small individuals as described above, it rides on the flow of the processing gas when falling in the tubular passage 21. It falls while turning in the tubular passage 21, so that the hovering time in the tubular passage 21 becomes longer than that at the time of free fall.

Then, during this long dwell time, the object to be processed W is brought into contact with the processing gas that has been converted into plasma in the tubular passage 21, whereby the surface treatment to the object to be processed W is performed.

However, the workpiece W that has been subjected to the surface treatment in the tubular passage 21 falls to the lower end opening of the tubular passage 21, and is then collected by the filter 61. In addition, the surface treatment process is completed by removing the collected workpiece W from the filter 61.

As described above, according to the plasma surface treatment apparatus according to the present invention, the object to be processed W is surface-treated by being brought into contact with the process gas converted into plasma in the tubular passage 21, so that the object to be processed is subjected to the surface treatment. W is not scattered or dissipated, and the surface treatment of the workpiece W can be performed without waste. In addition, since the surface treatment is completed in the tubular passage 21, the surface treatment can be performed with a small number of steps, and the surface treatment can be realized at a low cost.

In addition, since the workpiece W introduced into the tubular passage 21 falls while turning in the tubular passage 21, it is possible to increase the time during which the tubular passage 21 stays. As a result, sufficient contact between the object to be processed W and the processing gas can be achieved, and the surface treatment to the object to be processed W can be reliably performed. Furthermore, surface treatment without leakage can be performed even on the workpiece W having complicated unevenness.

Further, in the plasma surface treatment apparatus 1 according to the present invention, for example, by changing the length dimension of the tubular body 2, the dwell time of the object to be treated W in the tubular passage 21 (in other words, the object to be treated W). Therefore, it is possible to appropriately perform the surface treatment on the workpiece W having different materials and shapes.

Note that the above-described embodiments merely show preferred embodiments of the present invention, and the present invention is not limited to these, and various design changes can be made within the scope thereof.

For example, in the above-described embodiment, the case where the two

plasma generators

3 and 3 are arranged to face each other is shown as the configuration of the plasma surface treatment apparatus 1, but the plasma surface treatment apparatus 1 includes only one plasma generator 3. It is also possible to configure. Conversely, it is also possible to configure a plasma surface treatment apparatus using three or four plasma generators 3.

Further, in the above-described embodiment, the case where the tubular body 2 is arranged in the vertical direction (vertical) is shown. However, if the workpiece W can fall in the tubular passage 21 by riding on the flow of the processing gas, the tubular body 2 is tubular. It is also possible to arrange the body 2 at an angle.

DESCRIPTION OF SYMBOLS 1 Plasma surface treatment apparatus 2 Tubular body 3 Plasma generation apparatus 4 To-be-processed object accommodating part 5 Suction apparatus 6 Collection | recovery apparatus 21 Tubular channel | path 22 Gas introduction hole 31 Case 32 of plasma generation apparatus Bottom plate 33 Case 33 Filter W Workpiece

Claims

Facing the tubular passage where the object to be treated is dropped, a treatment gas spout is disposed along the arrangement direction of the tubular passage,
By injecting a plasma processing gas into the tubular passage from the processing gas jet port, a flow of the processing gas is formed in the tubular passage in a direction intersecting the arrangement direction of the tubular passage. Surface treatment of the object to be treated by introducing the object to be treated into the tubular passage from the upper end opening of the tubular passage and bringing the object to be treated into contact with the object to be treated while the object passes through the tubular passage. Performing a plasma surface treatment method.
The plasma surface treatment method according to claim 1, wherein the object to be treated is a chopped fiber.
2. The plasma surface treatment method according to claim 1, wherein the object to be treated is a granular material.
A tubular body having a tubular passage for dropping an object to be treated;
A plasma generator that faces the tubular passage and has a processing gas jet port disposed along a direction in which the tubular passage is disposed;
A plasma surface treatment comprising: a structure in which a flow of a processing gas is formed in the tubular passage in a direction intersecting with an arrangement direction of the tubular passage by the plasma-ized processing gas ejected from the jet outlet. apparatus.
The plasma generator is composed of two plasma generators arranged opposite to each other with the tubular body interposed therebetween,
The plasma surface treatment apparatus according to claim 4, wherein the jet outlets of the respective plasma generators are arranged with their positions shifted from each other.
The plasma surface treatment apparatus according to claim 4 or 5, wherein a suction device for sucking out an object to be processed that stays in the tubular passage to the outside of the tubular passage is provided on a lower end opening side of the tubular body. .
6. The plasma surface treatment apparatus according to claim 4, wherein a recovery device for recovering the object to be processed that has passed through the tubular passage is provided on the lower end opening side of the tubular body.