JPH0495B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides resins such as polypropylene (PP),
To modify the surface of polyethylene (PE), etc.
The present invention relates to an apparatus for subjecting the surfaces of these resins to plasma treatment.

In recent years, for example, there has been a trend toward plastics for automobile parts, which are lightweight and have excellent designs.
When relatively inexpensive polyolefin resins such as PP and PE are used for vehicle outer panels, it is known that the adhesion between the resin surface and the coating film is poor, resulting in the problem of delamination. One way to solve this problem is to expose the surface of the object to be coated, such as PP or PE, to plasma such as glow, corona discharge, radio waves, or microwave discharge to oxidize (introduce polar groups) or etch (introduce polar groups) the surface. Plasma surface treatment technology is known to improve the anchoring effect. In addition, when performing plasma treatment, in order to improve the treatment effect (lengthen the plasma life),
It is a known technique to provide a reduced pressure or vacuum in the reaction chamber. In order to maintain this state, batch processing is currently the mainstream.

Incidentally, in recent years, when plasma-treating resin molded products that require durability and productivity, plasma processing using a microwave method in which a plasma generation part and a reaction chamber are different is often used. In plasma processing using the microwave method, processing gas such as oxygen gas is turned into plasma by microwave discharge in a plasma generating section located outside the reaction chamber, and is transported to the reaction chamber through a transport pipe. In the reaction chamber, plasma is diffused by a shower tube made of quartz glass or the like to treat the surface of the object to be treated.

When four resin parts (W _{-1 to} 4) made of PP used in automobiles were processed using this type of conventional microwave plasma processing equipment (Fig. 6), it was found that the resin parts used in automobiles were large. In addition, since the shape is complicated, the processability varies depending on the placement position of the object to be processed in the reaction chamber or depending on the location of the same object to be processed (FIG. 7). In particular, W _-1-D , W _-2-C , which are shielded and have a long distance from the shower tube,
The treatment effect was inferior to the other areas in areas W _-3-B , _D , W _-4-A , and _C , and the adhesion of the coating film was also not satisfactory. Note that the processing conditions and evaluation method of the processed material in FIGS. 6 and 8 are as described later.

The present invention relates to a plasma processing apparatus that solves the above-mentioned problems and provides uniform processing even when processing a large number of large and complex-shaped objects at the same time.

That is, an object of the present invention is to eliminate differences in processing due to the positions of a plurality of objects to be processed in the reaction chamber and to eliminate processing errors due to the shape of the same object by making the plasma concentration distribution within the reaction chamber uniform. An object of the present invention is to provide a plasma processing apparatus that eliminates uniformity.

In order to achieve such an object, in the present invention, in an apparatus for treating the surface of a workpiece by irradiating plasma in a plasma reaction chamber, at least one first shower tube for plasma irradiation is provided in the reaction chamber. A plasma processing apparatus is proposed, which is fixedly installed on a wall and at least one second shower tube for plasma irradiation is provided so as to be movable to an arbitrary position within the reaction chamber.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In Fig. 1, reference numeral 1 denotes a reaction chamber made of a material such as SUS304, and inside it, resin (PP) parts to be treated _{-1 to 4} , which are automobile parts, are placed on a jig or a trolley (not shown). It is placed. 2 is a microwave oscillator (2450MHz) (for example, Toshiba Electric Corporation)
3 is a microwave waveguide, 4 is a plasma generation part with a quartz tube (connected to 7 and 8) inside, 5 is an oxygen gas cylinder, 6 is a valve, 7 is a nylon tube, and 8 is a generator The generated plasma is transferred to reaction chamber 1.
Transport pipe made of quartz glass for transport into the interior, 9,1
0, 14, 17, 20a, and 20b are similar transport pipes; 11 is a fluoro connector made of Teflon that connects and vacuum-seals the transport pipes 8 and 9; 12;
13, 15, 16, 18, 19, 34, 21, 2
5 and 27 are similar fluorocarbon connectors; 22 is a shear tube made of quartz glass as shown in detail in FIG. 3; 23 and 24 are similar shear tubes; 28 is a flexible Teflon tube that can be installed in the position shown in FIG.
29 is an exhaust port connected to a vacuum pump (not shown). 35, 36, 37, 38 are reaction chambers 1
and a flange (SUS304) for vacuum sealing each shower tube.

In the embodiment of FIG.
3 and 24 are fixedly installed on the inner wall of the reaction chamber 1 (the shower tubes 23 and 24 are approximately
90° apart). Although omitted in FIG. 1, the shower tubes 23 and 24 also have a microwave oscillator 2, a plasma generating section 4,
It is connected to an oxygen gas cylinder 5 or the like. The shower tubes 22, 23, 24 are composed of cylindrical quartz glass tubes as shown in FIGS. 3a and 3b, and the cylindrical reaction chamber 1
(Fig. 1).
A plasma injection port 40 consisting of a large number of small holes is provided on the side of the shower tubes 22, 23, 24 facing the inside of the reaction chamber 1.
is provided. These injection ports 40 are designed to irradiate plasma as uniformly as possible within the reaction chamber 1.
They are arranged in a staggered manner at a 60° angle. (Figure 3b).

On the other hand, the shower tube 28 can be installed at any position within the reaction chamber 1 via a flexible Teflon tube 26. In the embodiment shown in FIG. 1, the shower tube 28 is arranged in the axial direction at the center of the cylindrical reaction chamber 1, but it goes without saying that it can be installed at any position and angle depending on the number, shape, arrangement, etc. of the objects to be treated. . The shower pipe 28 is the shower pipe 22, 23, 2
Like 4, it is made of quartz glass tube, but the 4th
As shown in Figures a and b, for example, plasma can be irradiated in all radial directions with respect to the central axis.
Plasma injection ports 41 consisting of a large number of small holes are formed at equal angular intervals of 90 degrees. In the embodiment shown in FIG. 1, the plasma transport tube 20 of the shower tube 28 is branched from the fluoro connector 18, but it may be branched from the fluoro connector 12 or 15. Of course, it is also possible to provide Also, the first
In the embodiment shown in the figure, one shower tube 28 is provided in the center of the reaction chamber 1, but if the object to be treated is long in the axial direction and the plasma treatment effect at the long end portions is low, As shown in the embodiment, flexible Teflon tubes 26a and 26b similar to the flexible tube 26 are branch-connected to the fluoro connector 25, and
Shower tubes 31 and 33 with injection ports opening only in the direction of the object to be treated (at an angle of about 60 degrees) are attached to their tips via fluoro connectors 30 and 32, and these shower tubes 31 and 33 are used to direct the object to be treated. The plasma may be irradiated onto the ends of the object W in the longitudinal direction.

The above-mentioned showers 22, 23, 24 and 28, 31, 33 may be made of a material other than quartz glass, such as Pyrex glass, in which excited oxygen is not easily deactivated. Further, the flexible tubes 26, 26a, 26b need only be flexible so that excited oxygen is not easily deactivated like the shower tube, for example.
It may also be composed of a SUS coil spring or the like.

In FIG. 1, after the reaction chamber 1 is brought into a vacuum state by a vacuum pump (not shown) connected to the exhaust port 29, a predetermined amount of oxygen gas is supplied from the cylinder 5, and the inside of the reaction chamber 1 is evacuated by a vacuum valve (not shown). (not shown) to set the desired vacuum pressure. Thereafter, the oscillator 2 oscillates microwaves at a predetermined output, the waves are transmitted through the waveguide 3, and the plasma generator 4 generates plasma. The generated plasma is supplied to the shower tube 22 via the transport tubes 8, 9, 10 and the fluoro connectors 11, 12, 13. The plasma is supplied to the shower tubes 23 and 24 in the same way, but the plasma divided by the fluoro connector 18 is supplied to the shower tube 28.
0a, 20b, fluoro connectors 34, 21, 25
via the flexible tube 26 and is supplied from the flexible tube 26. In the embodiment shown in FIG. 5, the fluorocarbon connector 25 is further divided into flexible tubes 26a and 26b, and is also supplied to the shower tubes 31 and 33 via the fluoroconnectors 30 and 32.

Shower tubes 22, 23, 24 and 28 (31,
33), plasma is irradiated from the injection ports 40, 41 toward the surfaces of the objects W-1 _{to W-4 to uniformly treat the surfaces of the objects W-1 to W-4} . After the treatment for a predetermined period of time, the supply of oxygen gas, the oscillation of microwaves, and the evacuation by the vacuum pump are stopped, and the inside of the reaction chamber 1 is returned to the atmosphere. The objects to be treated W _{-1 to W -4} are then taken out from the reaction chamber 1 and subjected to coating.

FIG. 2 shows the measurement results when the objects to be processed W -1 to W _-4 (PP) were actually processed using the plasma processing apparatus of the present invention as shown in FIG. The processing conditions and evaluation method are the same as in the case of using the conventional plasma processing apparatus as shown in FIG. 6 (FIG. 7), and are as shown below.

Reaction chamber shape: 2000mm (diameter) x 2000mm (length) Processing conditions: Microwave frequency: 2450MHz Output: 500W Vacuum pressure: 0.5Torn Processing time: 30 seconds Processing gas amount: Oxygen, 5/min Evaluation method: Contact angle ( Measurement of θ) A 5μ drop of deionized water was placed on the PP surface after plasma treatment, and a contact angle measuring device (manufactured by Kyowa Chemical Co., Ltd.,
As is clear from the results shown in FIG. 2, the plasma processing apparatus of the present invention as shown in FIG. The plasma concentration in chamber 1 is made uniform, and even if the workpiece is relatively large and has a complicated shape, variations in plasma processing due to the placement position of the workpiece or the shape or location of the same workpiece are eliminated. Ta. Furthermore, the adhesion to the paint film after painting was also good in all parts.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the plasma processing apparatus of the present invention,
Figure 2 is a diagram showing the processing results in the plasma processing apparatus of the present invention, Figures 3a and b are detailed views of the shower tube fixed to the wall of the reaction chamber, and Figures 4a and b are views of the shower tube connected to the flexible tube. A detailed view of the shower tube, FIG. 5 is a schematic diagram showing another embodiment of the plasma processing apparatus of the present invention, and FIG. 6 is a schematic diagram of a conventional plasma processing apparatus.
FIG. 7 is a diagram showing processing results in a conventional plasma processing apparatus. 1... Reaction chamber, 22, 23, 24... Fixed shower tube, 28, 31, 33... Movable shower tube, 26, 26a, 26b... Flexible tube,
40, 41...Plasma injection port.

Claims (1)

[Scope of Claims] 1. In an apparatus for treating a surface of a workpiece by irradiating plasma in a plasma reaction chamber 1, at least one first shower tube 22 for plasma irradiation;
23, 24 are fixedly installed on the walls of the reaction chamber, and at least one second shower tube 28, 31, 33 for plasma irradiation is provided so as to be movable to any position within the reaction chamber. plasma processing equipment. 2 The second shower tube is a flexible tube 26, 26a, 26 attached to the plasma introduction part 25 on the wall of the reaction chamber.
2. The device according to claim 1, wherein the device is connected via b. 3. The second shower tube is constituted by a cylindrical tube, and has a large number of plasma injection ports 41 over the entire circumference to irradiate plasma from the center of the cylindrical tube in all radial directions. The device according to item 2.