JPH0153897B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention primarily relates to a method and apparatus for subjecting the surfaces of resins such as polypropylene (PP), polyethylene (PE), etc. to plasma treatment in order to modify their surfaces. In particular, the present invention
When painting a relatively large and complicatedly shaped resin part, it can be effectively used as a pre-treatment for painting.

In recent years, for example, there has been a tendency to use resins for automobile parts, which are easily recyclable and have excellent design properties, but when relatively inexpensive PP, PE, etc. are used, for example, for vehicle outer panels, the resin surface and coating It is known that adhesion with the film is poor and problems such as delamination occur. One way to resolve this problem is to expose the surface of the object to be coated, such as PP or PE, to glow, corona, radio waves, or microwave discharge before painting to oxidize (introduce polar groups) or etch (introduce polar groups) the surface. Plasma treatment technology that improves the anchoring effect is known.

By the way, when performing plasma processing, in order to improve the processing effect (lengthen the life of the plasma), it is necessary to reduce the pressure in the reaction chamber or bring it into a vacuum state. In order to maintain this state, batch processing is currently the mainstream.

On the other hand, in order to introduce this processing method into the mass production process of manufacturing automobile parts, it is necessary to reach a vacuum state in a short time and to plasma-process a larger number of objects at one time. Considering this point, when processing with a conventional plasma processing device (microwave discharge plasma device, Fig. 9), the resin parts used in automobiles are large and have complex shapes, so
The processability differed between the objects to be treated depending on the placement position of the objects in the reaction chamber, and the processability also differed between parts of the same object.

In Fig. 9, 1 is a reaction chamber, 2 is a microwave oscillator, 3 is an isolator (manufactured by Toshiba Corporation), 4 is a power monitor (manufactured by Toshiba Corporation), 5 is a three-stub tuber (manufactured by Toshiba Corporation), and 6 1 is a plasma generation furnace, 7 is a plasma generation tube, 8 is a quartz tube, 9 is a plasma introduction port, 12 is a glass tube, 15 is an exhaust port for reducing the pressure inside the reaction chamber, 16 is a gas supply pipe, 17
is a flowmeter, 18 is a gas cylinder, 19 is a waveguide, S
-1 to 6 are objects to be processed.

In order to solve the above-mentioned problems in the conventional microwave discharge plasma apparatus shown in FIG. 9, the following preliminary experiment was conducted.

* Preliminary experiment method (evaluated using PP to be processed) [Reaction processing chamber] 2000mm diameter x 2000mm length [Processing conditions] Microwave frequency: 2450MHz Output: 500W Vacuum pressure: 0.5 Torr Processing gas (amount): Oxygen (5000c) c./min) Processing time: 30 seconds [Glass tube] Plasma injection angle α of glass tube 12 (Figure 10)
As shown in Figure 11, α=0°, α=30°, α=
The experiment was conducted by selecting 60°.

[Arrangement of objects to be treated]

The processing object (PP) is arranged so that the distance H from the plasma injection port of the glass tube 12 to the processing object surface along the center line of the injection angle α is H=500 mm and H= It was set to 1000mm. Also,
From a position at a distance H along the center line of the injection angle α, right and left W (W = 0 to
The contact angle after the surface plasma treatment of the object to be treated was measured at a position moved by a distance of 1000 mm), and the results are shown in FIG.

[Contact angle measurement method]

Apply deionized water to the PP surface after plasma treatment.
A 5 μm drop was added and measured using a contact angle measuring device (Model CA-A, manufactured by Kyowa Kagaku) (20° C., 50-60% atmosphere).

As a result of the above preliminary experiments, the following points were clarified as shown in FIG.

1 The lifetime of the plasma introduced into the reaction chamber 1 is determined by the distance between the injection port provided in the glass tube 12 and the object to be processed.

2 The diffusivity of the plasma introduced into the reaction chamber 1 is
It is determined by the position (angle α) of the injection port provided in the glass tube 12 that injects plasma.

Although not shown in Figure 11, the above 1),
In addition to item 2), due to the shielding effect of the processed material,
It has also become clear that plasma processability is affected. It is thought that these are all caused by non-uniform plasma concentration within the reaction chamber.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for plasma processing that solves the above problems and provides uniformity of processing even when processing a large number of relatively 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 by making the plasma concentration distribution within the reaction chamber uniform, and to eliminate differences in processing depending on the position of a plurality of objects to be processed in the reaction chamber, and to eliminate differences in processing due to the shape of the same object. An object of the present invention is to provide a method and apparatus for performing plasma processing that eliminates non-uniformity.

The plasma processing method of the present invention that achieves the above purpose is a method in which the surface of an object to be treated is irradiated with microwave discharge plasma in a plasma reaction chamber, and a plurality of locations adjacent to the wall of the reaction chamber are treated. The present invention is characterized in that the plasma is injected into the reaction chamber from the above, and the plasma is injected at a constant angle at each plasma injection point.

Furthermore, the apparatus of the present invention processes the surface of the workpiece by irradiating it with microwave discharge plasma in a vacuum reaction chamber shaped like a cylinder with a diameter of 1000 mm or more, a square prism with a side of 1000 mm or more, or a similar shape. The apparatus is characterized in that plasma introduction ports are provided at a plurality of arbitrary positions on the wall of the reaction chamber, and each plasma introduction port is connected to a glass tube that injects plasma into the reaction chamber at a fixed angle.

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 8.

1 and 2 show a first embodiment of the device according to the invention, ie an embodiment in which the reaction chamber 1 is cylindrical. In these figures, 1 is a cylindrical reaction chamber with a diameter of 1000 mm or more, 2 is a microwave oscillator, 3 is an isolator (manufactured by Toshiba Corporation), 4 is a power monitor (manufactured by Toshiba Corporation), and 5 is a sleeve tube tuner (manufactured by Toshiba Corporation). ), 6 is a plasma generation furnace, 7 is a plasma generation tube, 8 is a quartz tube, 9 (9-A, B), 10, 11
are plasma introduction ports, 12 (12-A, B), 13
(13-A, B), 14 is a glass tube, 15 (15-
A, B) are exhaust ports for reducing the pressure inside the reaction chamber 1;
16 is a gas supply pipe, and 19 is a waveguide. Microwaves generated by the oscillator 2 are guided to the plasma generation furnace 6 via a waveguide 19 via an isolator 3, a power monitor 4, and a three-stub tuner 5. On the other hand, plasma gas is supplied to the plasma generation furnace 6 through a pipe 16. Plasma generated in the plasma generation furnace 6 and the plasma generation tube 7 is introduced into the reaction tube 1 through the plasma introduction ports 9 to 11-A and B through the quartz tube 8, but in the first embodiment, the introduction ports are connected in three directions. (direction rotated by 60 degrees) at two locations 11-A and B each.
(not shown), 12-A, B, and 13-A, B were installed. In addition, the plasma introduced into the introduction ports 9 to 11-A and B is transferred to the glass tubes 12 to 14-B connected thereto.
The plasma is injected into the reaction chamber 1 at points A and B, and details of the plasma injection port installed in the glass tube at that time are shown in FIGS. 5 to 7. On the other hand, in order to perform plasma processing, a vacuum (approximately 1.0 to 0.05 Torr) is required in the processing container 1.
Therefore, the exhaust port 15 is connected to a vacuum pump (not shown) via piping (not shown) for continuous evacuation.

FIGS. 3 and 4 show a second embodiment of the apparatus of the present invention, that is, an embodiment in which the reaction chamber 1 is in the shape of a square prism with each side of 1000 mm or more. Portions corresponding to those in the first embodiment are indicated by the same numbers. The reaction chamber 1 has a rectangular prism shape, for example, plasma introduction ports 9-1, 9-
The side X (Fig. 4) having 2 is 2500 mm, and the side Y (Fig. 4) having plasma inlets 10 and 11 is 2500 mm.
It is 1800mm. As shown in FIG. 4, a plurality of plasma introduction ports 9-1 and 9-2 are provided on the wall of side X at intervals of 1000 mm or less (for example, 900 mm). Other configurations and operations are the same as in the first embodiment.

In FIGS. 5 to 7, plasma introduction ports 9, 10,
11-A, B (first example) or 9-1, 2-A,
Glass tubes 12, 13, 14-A, B (first embodiment) or 12-1, 2-A, B, 13, connected to B, 10, 11-A, B, (second embodiment) 14
- Examples of A and B (second embodiment) are shown. The glass tube 20 is preferably made of glass or quartz, and the root portion 21 of the glass tube 20 is connected to the plasma introduction ports 9, 10, 11. Root part 21
It extends from the manifold section 22 to the cylindrical spray head section 23. This spray head portion 23 extends perpendicularly to the central axis _X1 of the plasma introduction port by an equal distance on the left and right sides, and both ends thereof are closed. A plurality of plasma inlet irradiation ports 24 each having a diameter of, for example, 6 mm are provided on the lower side of the spray head portion 23 at regular intervals in the longitudinal direction. These plasma irradiation ports 24, which are adjacent to each other, are arranged at an angle of α=60° with respect to the glass tube center line _X2 (an angle rotated by 30° with respect to _X1) , as shown in FIG. ) and are arranged in a staggered manner. Therefore, the plasma is distributed at a plurality of locations 1 adjacent to the inner wall of the reaction chamber 1.
Plasma is injected into the reaction chamber from 2, 13, 14 (FIG. 2), and at a constant angle at each injection location 12, 13, 14.

Figure 8 shows the processed material (PP) using the device of the present invention.
This figure shows the measurement results when processed.
That is, the apparatus of the first embodiment (FIGS. 1 and 2)
An experiment was conducted by incorporating the glass tubes shown in FIGS. 5 to 7. In this case, as shown in FIG. 1, the glass tube is assembled so that the longitudinal direction of the glass tube is in the axial direction of the cylindrical reaction chamber 1.
The size of the [reaction treatment chamber], [processing conditions], and [method for measuring contact angle] were the same as in the preliminary experiment. Regarding [placement of the object to be treated], the distance from the plasma injection port to the surface of the object to be treated is H=
Measurements were made for the case of 500 mm and the case of H = 1000 mm (however, in this case, H is the glass tube 12 (second
(Fig.) to the object to be processed), W=0~
Measurements were made on the object to be treated within a range of 1000 mm (the definition of W is the same as in the preliminary experiment). Other conditions were the same as in the preliminary experiment.

As is clear from the experimental results shown in FIG. 8, according to the present invention, the plasma concentration in the reaction chamber is made uniform, and even when a large number of relatively large and complex-shaped objects are processed at the same time, each Differences in processing depending on the position of the object to be processed can be eliminated, and non-uniformity in processing depending on the shape of the same object can also be eliminated.

In addition, in the case of a processing container other than a cylindrical shape, for example, a prismatic shape, the idea of installing plasma inlets at intervals of 1000 mm or less is the most desirable and effective idea, but as long as it does not depart from the spirit of the present invention. Other methods conceived based on the knowledge of those skilled in the art may also be adopted as appropriate.

[Brief explanation of drawings]

FIG. 1 is a side view of a first embodiment of the apparatus for plasma processing of the present invention, FIG. 2 is a schematic sectional view thereof, FIG. 3 is a side view of a second embodiment of the apparatus of the present invention, and FIG.
5 is a front view of the glass tube used in the device of the present invention, FIG. 6 is a view taken from the arrow in FIG. 5, and FIG. 7 is a view taken from the arrow in FIG. 5. , FIG. 8 is a diagram showing experimental results of plasma processing according to the present invention, FIG. 9 is a schematic cross-sectional view of a conventional plasma processing apparatus, and FIG.
A diagram showing an improved state of the glass tube of the device shown in the figure, and FIG. 11 is a diagram showing the results of a preliminary experiment. 1...Reaction chamber, 2...Microwave oscillator, 3...
...Isolator, 4...Power monitor, 5...Three stub tuber, 6...Plasma generator, 7...
...Plasma generation tube, 8...Quartz tube, 9-11...
Plasma introduction port, 12-14, 20... (glass tube), 15... exhaust port, 16... gas supply pipe, 1
9... Waveguide, 24... Plasma irradiation port.

Claims (1)

[Scope of Claims] 1. A method for treating a surface of a workpiece by irradiating microwave discharge plasma in a plasma reaction chamber, which comprises injecting plasma into the reaction chamber from a plurality of locations adjacent to the wall of the reaction chamber, and , a plasma treatment method in which plasma is injected at a fixed angle at each plasma injection point. 2 A cylinder with a diameter of 1000mm or more or a side of 1000mm
In a device that processes the surface of a workpiece by irradiating microwave discharge plasma on the surface of the workpiece in a vacuum reaction chamber with a rectangular prism shape of mm or more, or a similar shape, plasma introduction ports are installed at multiple arbitrary positions on the wall of the reaction chamber. An apparatus for performing plasma processing, characterized in that a glass tube is connected to each plasma introduction port to inject plasma into a reaction chamber at a fixed angle. 3. The reaction chamber has a cylindrical shape with a diameter of 1000 mm or more, and a plasma introduction port 9 is provided at an arbitrary position on the wall of the reaction chamber, and a position rotated by 45 to 120 degrees in at least one circumferential direction from that position. 3. The apparatus according to claim 2, wherein at least one plasma inlet 10, 11 is provided in the plasma inlet 10, 11. 4 Plasma inlet 9- is installed at an interval of at least less than 1000 mm from the arbitrarily installed plasma inlet in a rectangular prism-shaped reaction chamber with sides of 1000 mm or more.
1,9-2. 5. A cylindrical glass tube made of quartz, glass, etc. extends in the longitudinal direction of the reaction chamber orthogonal to the center line of the plasma introduction port, and the cylindrical glass tube is provided with a plurality of plasma irradiation ports. , these plasma irradiation ports are formed at intervals of 15 to 90 degrees, preferably 30 to 60 degrees in the circumferential direction, and the plasma is injected at a constant angle with respect to the central axis of the glass tube. The apparatus according to the range 2, 3 or 4. 6. The apparatus according to claim 5, wherein the plurality of plasma irradiation ports are provided at equal intervals in the axial direction of the cylindrical glass tube and arranged in a staggered manner. 7. The apparatus according to claim 5 or 6, wherein the angle in the circumferential direction of the glass tube in which the plurality of plasma irradiation ports are arranged is divided into two with respect to the center line of the plasma introduction port.