JPH0615629B2 - Plasma processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma processing method, and more particularly to a plasma processing method for achieving uniform processing on an object to be processed.

(Prior Art) Olefin resins such as PP (polypropylene) and PE (polyethylene) are relatively excellent in weather resistance, mechanical strength, moldability, etc. There is a tendency for more and more automobile parts to be used.

On the other hand, the olein-based resin has high crystallinity and non-polarity, and thus has poor surface activity, and cannot provide adhesiveness during so-called secondary processing such as painting, printing and adhesion, which is a bottleneck.

Flame treatment, ultraviolet radiation treatment, corona discharge treatment, plasma treatment using radio waves and microwaves, and the like are considered as measures to give activation to these.

In automotive materials, from the balance of the above physical properties and costs,
In particular, the use of polypropylene has increased, and the bumpers in particular have far exceeded conventional steel and urethane. However, the bumper has come to be considered as a part of the body panel from the viewpoint of diversifying design and improving aerodynamic performance.
The color is often the same as the body color, instead of the conventional resin color (mostly black).

Therefore, when applying the coating to Vapa, although the above-mentioned modification method is used in part, most of them are undercoated with a chlorinated olefin or the like before the body color is applied. . When this undercoating process becomes a large part such as a bumper, it requires a large area for a coating booth and a drying furnace, and the power cost of steam, electric power, etc. is enormous. It is not preferable in terms of aspect. Therefore, application of the plasma treatment method among the above-mentioned reforming methods has been studied from the viewpoint of treatment stability for large-sized products.

(Problems to be solved by the invention) However, even in this plasma treatment, it is difficult to uniformly bring an excited gas such as oxygen or nitrogen, which contributes to surface modification, to the molded product, and it is difficult for the plasma gas to come into contact with the molded product. The processing at the corners and the like tends to be inadequate, causing problems such as paint peeling. Therefore, at present, measures such as lengthening the processing time are taken, but the cycle time is extended, which is not preferable for production. Especially when it is installed on a line, etc., it cannot be balanced with other processes, which is a big problem.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a plasma processing method capable of achieving uniform processing on an object to be processed.

(Means for Solving Problems) The plasma processing method according to the present invention is intended to make the processing uniform by adjusting the output of an electromagnetic wave oscillator that generates plasma gas. That is, a plasma gas generated by an electromagnetic wave oscillator provided in each of the plurality of inlets is introduced from the plurality of inlets and flows down into the plasma processing chamber toward a plurality of outlets corresponding to each of the inlets. By performing the plasma treatment on the object to be processed in the plasma processing chamber, a plurality of surfaces of the surface to be processed of the plurality of electromagnetic wave oscillators along the flow-down direction of the plasma gas are increased. It is characterized in that the output of the electromagnetic wave oscillator provided at the inlet for introducing the plasma gas for processing the surface to be processed is set to be higher than the output of other electromagnetic wave oscillators.

(Operation) With the above configuration, the concentration of the plasma gas for treating the surface to be treated, which is less likely to come into contact with the plasma gas, is relatively high, so that the amount of treatment gas per unit area in each portion of the surface to be treated is made uniform, A uniform plasma treatment is applied to the entire surface to be treated.

(Effect of the invention) Therefore, according to the present invention, even if the object to be processed has a complicated surface shape to be processed, uniform plasma processing can be performed, and the processing time is shortened. The time can be shortened, synchronization with other processes can be achieved, and line production becomes easy. Also,
When a coating process is applied in a later step, it becomes possible to form a uniform coating film.

Embodiment An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side sectional view showing a plasma processing apparatus used in the plasma processing method according to this embodiment.

The plasma processing chamber 1 is composed of a cylindrical chamber 2 and an inlet-side door 3 and an outlet-side door 4 which are openably and closably provided at both ends thereof. Are placed on the net conveyor 6. At the upper end of the cylindrical chamber 2, three plasma generation furnaces 7 are arranged at predetermined intervals along the longitudinal direction of the cylindrical chamber 2. Each plasma generation furnace 7 has a plasma processing chamber 1
Shower tube 8, which is an inlet for introducing plasma gas into the inside,
A stab tuner 9 and an electromagnetic wave oscillator 10 are provided so that a gas such as oxygen supplied from the processing gas supply source 11 through the introduction side flow rate adjusting valve 12 is turned into plasma and introduced into the plasma processing chamber 1 from the shower tube 8. It has become.

At the lower end of the cylindrical chamber 2, discharge ports 13 are formed at three locations corresponding to the shower tubes 8 of the plasma generation furnace 7. Each discharge port 13 communicates with the mechanical booster pump 15 and the rotary pump 16 via each discharge side flow rate adjusting valve 14, and the mechanical booster pump 15 is provided with a bypass flow passage in which a bypass valve 17 is interposed. Has been done.

When the plasma processing is performed on the work 5, the pressure inside the plasma processing chamber 1 is reduced to about 0.5 Torr, but the bypass valve 17 is opened and exhausted only by the rotary pump 16 until it reaches about 20 Torr. The decompression of the bypass valve
The mechanical booster pump 15 and the rotary pump 16 are directly connected to each other by closing 17 and both of them are to be used. At this time, in order to maintain the airtightness inside the plasma processing chamber 1, silicon rubber seals 18 are respectively interposed between the cylindrical chamber 2 and the inlet side door 3 and the outlet side door 4.

When the inside of the plasma processing chamber 1 is depressurized to a predetermined degree of vacuum,
The plasma gas generated by the electromagnetic wave oscillator 10 in each plasma generation path 7 is introduced into the plasma chamber 1 from each chaper pipe 8 and flows down in the plasma chamber 1 toward each discharge port 13, and at that time to the work 5. Plasma treatment is performed.
At this time, the plasma gas introduced from each shower tube 8 flows in the direction in which it flows most easily and is discharged from each discharge port 13.

Therefore, when the object to be processed is the work 5 having the bumper shape as shown in FIG. 1, the plasma gas flows from the shower tube 8 to the discharge port 13 like the upper surface 5a of the surface to be processed of the work 5. The surface portion to be processed having a surface substantially orthogonal to the direction is easily subjected to plasma gas processing, and the processing time is short, however, like the side surface portions 5b on the left and right, the surface along the flow direction of the plasma gas. It is difficult to perform plasma treatment on the surface portion having many defects in a short time. Therefore, it takes a long time to perform plasma processing on the entire surface to be processed of the work 5.

Therefore, in the plasma processing method according to the present embodiment, the concentration distribution of the plasma gas in the plasma processing chamber 1 is adjusted according to the shape of the object to be processed. Specifically, each electromagnetic wave oscillator 10 of the three plasma gas generating furnaces 7
The discharge amount of plasma gas from each shower tube 8 is adjusted by adjusting the mutual output, and thereby the concentration distribution of plasma gas in the plasma processing chamber 1 is adjusted. For example, for the work 5 having the shape as shown in FIG. 1, among the electromagnetic wave oscillators 10 of the three plasma gas generating furnaces 7, the electromagnetic wave oscillator of the central generating furnace 7 is used.
For the output of 10, the electromagnetic wave oscillators of the generator 7 on both the left and right sides
By setting the output of 10 to be high, the concentration of the plasma gas for processing the left and right side surfaces 5b having many surfaces along the flow direction of the plasma gas among the processed surfaces of the work 5 is relatively high, As a result, it is possible to make the plasma processing uniform in each part of the surface to be processed.

Even if the object to be processed has a bumper shape, the length of the side surface portion is short, and unless the surface side surface portion 5b of the work 5 has a large number of surfaces along the flowing direction of the plasma gas, each plasma generation furnace The outputs of the electromagnetic wave oscillator 10 of 7 may be set to be the same.

FIG. 2 is a view showing a control mechanism for adjusting the three units in order to make the plasma treatment of the work 5 uniform.

The work 5 is transferred from the conveyor 19 to the conveyor 20 via the net conveyor 6 and is subjected to the above plasma treatment while being placed on the net conveyor 6, but is placed on the station before the treatment, that is, the conveyor 19. In this state, the work shape recognition means (CCD) 21 previously recognizes the shape of the surface to be processed of the work 5. Based on the output signal from the work shape recognition means 21, the CPU 22 sets the output of each electromagnetic wave oscillator 10.

By providing the control mechanism as described above, it is possible to automate and process plasma processing, and it is possible to process many kinds of works on the same line, and it is easy to synchronize with other processes. .

[Brief description of drawings]

FIG. 1 is a side sectional view showing an example of a plasma processing apparatus used in a plasma processing method according to the present invention, and FIG. 2 is a view showing an output control mechanism for adjusting the concentration of plasma gas in the plasma processing method. is there. 1 ... Plasma processing chamber 5 ... Work 7 ... Plasma generation furnace 8 ... Shower tube 10 ... Electromagnetic wave oscillator 13 ... Discharge port

Claims (1)

[Claims] 1. Plasma treatment is performed by introducing a plasma gas generated by an electromagnetic wave oscillator provided in each of the plurality of inlets from the plurality of inlets and toward a plurality of outlets corresponding to each of the inlets. A method of subjecting an object to be processed in the plasma processing chamber to plasma processing by flowing down the inside of the chamber, wherein the plurality of electromagnetic wave oscillators are arranged along a flow direction of a plasma gas on a surface to be processed of the object to be processed. A plasma processing method characterized in that the output of an electromagnetic wave oscillator provided at an inlet for introducing a plasma gas for processing a surface to be processed having a large number of surfaces is set to be higher than the outputs of other electromagnetic wave oscillators.