JP2000058223A - Surface modifying treatment method and surface modifying treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost and compact surface modifying treatment device using a plasma capable of generating high-voltage and high frequency discharge voltage by using a DC power source with relatively low output voltage. SOLUTION: In this surface modifying treatment device T1, discharge voltage for generating corona discharge is generated by superimposing pulse voltage on steady DC voltage. Therefore, high voltage, high frequency discharge voltage capable of conducting a sufficient plasma treatment or a corona discharge treatment to a treating material 3 can be obtained without increasing so much pulse voltage or steady DC voltage. Output voltage of a first DC power source 5 or a first DC power source 17 can relatively be lowered, the insulation mechanism of a circuit is simplified, and production cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention modifies the surface characteristics of an object to be processed by utilizing a plasma generated by applying a high discharge voltage between a discharge electrode and a counter electrode, which is generated by corona discharge. The present invention relates to a surface reforming method and a surface reforming apparatus, and in particular, a resin molded product, a resin, in which a power supply voltage is reduced by generating a discharge voltage by superimposing a pulse voltage and a steady DC voltage. Sheet,
The present invention relates to a surface modification treatment method and a surface modification treatment device capable of improving the paintability, printability, adhesiveness, hygroscopicity, hydrophilicity, and the like of the surface of a resin film, paper, cloth, nonwoven fabric, metal plate, and the like. is there.

[0002]

2. Description of the Related Art Generally, resin (plastic), paper,
When applying decoration such as painting and printing to the object to be processed formed of cloth, metal, etc., or when bonding another member to these,
In order to improve the paintability, printability, adhesiveness, hydrophilicity, hygroscopicity and the like of the surface of the object, the surface of the object is often subjected to a surface modification treatment. As one of such surface modification treatment methods, a plasma treatment or a corona discharge treatment in which plasma generated in the air by corona discharge is applied (irradiated) to the surface of the object to be treated to modify the surface. Is conventionally known (for example, see Japanese Patent Application Laid-Open No. Hei 5-33997).
Reference).

[0003] Such a plasma surface modification apparatus is usually provided with a plasma generator for generating plasma in the air near the object by corona discharge.
Generally, such a plasma generator applies a high voltage and a high frequency pulse voltage between a discharge electrode and a counter electrode facing each other to cause corona discharge in a gap between both electrodes to generate plasma in the air. It has become. The object to be processed is placed stationary in the gap between the two electrodes, or is passed through the gap at an appropriate speed, and the surface thereof is subjected to plasma processing.

[0004]

However, in such a surface reforming apparatus utilizing plasma, as described above, the object to be processed is not disposed stationary in the gap between the discharge electrode and the counter electrode. Since the electrodes must pass through, the distance between the two electrodes (distance between the electrodes) needs to be considerably large depending on the form of the object to be processed. For this reason, when it is necessary to perform plasma processing on various objects to be processed having different shapes or dimensions, it is practical to set the distance between the two electrodes of the surface modification apparatus to about 30 cm.

Here, the peak value of the pulse voltage required to cause corona discharge between the two electrodes increases as the distance between the two electrodes increases, but the peak value between the two electrodes becomes 3.
In the case of about 0 cm, a pulse voltage having a peak value of about 200 KV or more is required to induce a corona discharge capable of obtaining a sufficient surface modification treatment effect in air under normal pressure. When a pulse voltage having a peak value of 200 KV is generated using a DC power supply, the output voltage required for the DC power supply becomes considerably high (for example, 180 KV or more).

However, when the output voltage of the DC power supply is increased as described above, the insulating mechanism of the DC power supply and the pulse voltage generation circuit becomes very large, and a circuit element that can sufficiently withstand the high voltage is used. There must be. For this reason, the production cost of the surface reforming apparatus becomes very high, the power supply capacity becomes large, and the surface reforming apparatus becomes large. Even if the power supply capacity is small, if the output voltage is high, the insulation mechanism is of course large-scale.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is possible to generate a high-voltage and high-frequency discharge voltage using a DC power supply having a relatively low output voltage. The problem to be solved is to provide a low-cost and compact surface modification treatment apparatus or method capable of performing a sufficient surface modification treatment on an object to be treated by plasma generated by voltage-induced corona discharge. And

[0008]

Means for Solving the Problems The surface modification method according to the first aspect of the present invention, which has been made to solve the above-mentioned problems, has a high pressure (high frequency) between opposing discharge electrodes and counter electrodes. ), A corona discharge is induced in the gap between the two electrodes (in air under normal pressure) to generate plasma, and the object to be processed is disposed (moved) in the gap between the two electrodes.
In the surface reforming method, wherein the surface property of the object is modified by plasma, the discharge voltage is generated by superimposing (superimposing) a pulse voltage and a steady DC voltage. It is characterized by the following.

In this surface modification treatment method, a discharge voltage for inducing a corona discharge is generated by superimposing a pulse voltage and a steady DC voltage. Even without this, it is possible to obtain a high-voltage (peak value) and high-frequency discharge voltage capable of performing sufficient plasma treatment or corona discharge treatment on the object. Therefore, the output voltage of the power supply for generating the pulse voltage or the power supply for generating the steady DC voltage can be made relatively low. For this reason, a simple insulating mechanism of a circuit for generating a power supply or a discharge voltage can be used, and a circuit element having a relatively low withstand voltage can be used. The mechanism is simplified or made compact, and its manufacturing cost is reduced. That is, the object to be processed can be subjected to the surface modification treatment by plasma at low cost. In this case, a mechanism for generating a steady DC voltage is required, and the manufacturing cost and the device capacity are increased by that amount. In addition, the manufacturing cost and the device capacity are reduced.

[0010] In the above surface modification treatment method, it is preferable that the pulse voltage is generated by performing a gap discharge of the DC power supplied from the DC power supply. Preferably, the output voltage of the DC power supply is set to 200 KV or less, and the steady DC voltage is set to 100 KV or less. This makes it possible to generate a pulse voltage having a high repetition frequency from a DC voltage with a simple circuit structure.

In the above-mentioned surface modification treatment method, a DC power supply may be used as a power supply for a steady DC voltage. With this configuration, a pulse voltage and a steady DC voltage can be generated by one DC power supply, so that the circuit structure is simplified.

A surface modification treatment apparatus according to a second aspect of the present invention comprises: (a) a discharge electrode; (b) a counter electrode disposed so as to face the discharge electrode; (D) applying the discharge voltage between the two electrodes by the high voltage application means to cause a corona discharge in a gap between the two electrodes. (E) the high-voltage applying means comprises: Pulse voltage applying means for applying a pulse voltage in between,
(F) a stationary DC voltage applying means for applying a stationary DC voltage by superimposing (overlapping) the pulse voltage between the two electrodes.

In this surface reforming apparatus, a discharge voltage for inducing a corona discharge is generated by superimposing (superimposing) a pulse voltage and a steady DC voltage. It is possible to obtain a high-voltage (peak value) and high-frequency discharge voltage that allows sufficient plasma treatment or corona discharge treatment to be performed on the object to be processed without increasing the temperature. Therefore, the output voltage of the power supply of the pulse voltage application means or the power supply of the steady DC voltage application means can be reduced. For this reason, the insulating mechanism of the circuit for generating the power supply or the discharge voltage can be simplified, and a circuit element having a relatively low withstand voltage can be used, so that the surface reforming apparatus can be simplified or compact. And the manufacturing cost is reduced. That is, the cost of the surface modification treatment of the object to be treated by the plasma is reduced. In this case, the production cost and the apparatus capacity increase by the provision of the steady DC voltage applying means. However, even considering these increases, the production cost and the apparatus capacity of the entire surface reforming apparatus are still low. Reduced.

In the above surface reforming apparatus, the pulse voltage applying means includes a DC power supply and a gap discharge switch circuit (gap) for converting the DC voltage supplied from the DC power supply into a pulse voltage and applying the pulse voltage between both electrodes. Switch circuit). Note that the output voltage of the DC power supply is preferably 200 KV or less, and the steady DC voltage is preferably 100 KV or less. With this configuration, a high-frequency pulse voltage can be generated from a DC voltage with a simple circuit structure.

In the above-described surface reforming apparatus, it is preferable that the DC power supply of the pulse voltage applying means also serves as the power supply of the steady DC voltage applying means. With this configuration, a pulse voltage and a steady DC voltage can be generated by one DC power supply, so that the circuit structure is simplified.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. (Embodiment 1) As shown in FIG. 1A, in a surface modification treatment apparatus T1 according to Embodiment 1 of the present invention, a discharge electrode 1 and a discharge electrode 1 are disposed so as to face each other. A counter electrode 2 is provided, and the electrodes 1 and 2 are arranged in air under normal pressure with an appropriate interval (for example, 30 cm) according to the shape or size of the workpiece 3. In other words, the electrodes 1 and 2 are arranged with an appropriate distance between them so that the object 3 can pass through the gap or the object 3 can be arranged stationary in the gap. Have been.

A pulse voltage generated by the pulse voltage generation circuit C ₁ and a steady DC voltage generated by the steady DC voltage generation circuit C ₂ are superposed between the discharge electrode 1 and the counter electrode 2 ( (Overlapping), a high voltage and a high frequency discharge voltage are applied. When a discharge voltage is applied between the electrodes 1 and 2,
Corona discharge is induced in the gap between the two electrodes 1 and 2, and the plasma 4 is generated by the corona discharge.

As described above, when the discharge voltage is applied between the electrodes 1 and 2 and the plasma 4 is generated in the gap between the electrodes 1 and 2, the workpiece 3 is passed through the gap. ,
Alternatively, the surface of the processing object 3 is modified by the plasma 4 as a result,
Printability, adhesiveness, hygroscopicity, hydrophilicity, etc. are improved. The object 3 that can be modified by the plasma is
For example, resin molded products (plastic molded products),
Examples include a resin sheet (plastic sheet), a resin film (plastic film), paper, cloth, nonwoven fabric, and a metal plate.

The pulse voltage generating circuit C ₁ has a first DC power supply 5, a first conductor 6 having one end connected to the negative pole of the first DC power supply 5 and the other end connected to the discharge electrode 1, and one end connected to the discharge electrode 1. First
A second conductor 7 is connected to the positive pole of the DC power supply 5 and the other end is connected to the counter electrode 2. And the first
A first protection resistor 8, a charge / discharge capacitor 9, and a coupling capacitor 10 are provided in series on the conductive wire 6 in order from the first series power supply 5 side to the discharge electrode 1 side.

In the pulse voltage generating circuit C ₁ , there is provided a third conductor 11 connecting the point P _{1 of} the first conductor 6 and the point P _{2 of} the second conductor 7, and this third conductor 11 has , P
In order from _one point side P ₂ point side, the coil 12 (inductance) and the gap switch 13 is interposed in series. Incidentally, P ₂ points of the second conductor 7 is connected to ground 14. Further, a fourth conductor 15 is provided for connecting the point P _{3 of} the first conductor 6 to the point P _{4 of} the second conductor 7, and a load resistor 16 is provided on the fourth conductor 15.

On the other hand, the stationary DC voltage generating circuit C ₂ has a second DC power supply 17 (DC superimposing power supply) and one end connected to the positive pole of the second DC power supply 17 and the other end connected to the P terminal of the first conductor 6. _Five
Fifth conductive wire 18 connected to a point (and, consequently, discharge electrode 1)
And a sixth conducting wire 19 having one end connected to the negative pole of the second DC power supply 17 and the other end connected to the point P _{6 of} the second conducting wire 7 (therefore, the counter electrode 2). A second protection resistor 20 (a DC superimposition protection resistor) is provided on the fifth conductor 18.

[0022] Thus, in the pulse voltage generating circuit C _1, the output voltage of the first DC power supply 5, in the following process, a pulse voltage voltage frequently vibrates (variation) is generated. That is, when the first DC power supply 5 is first turned on, the negative electrode 9a of the charge / discharge capacitor 9
The conductor 6 (including the first protection resistor 8) is connected to the negative pole of the first DC power supply 5, while the positive electrode 9b connects the fourth conductor 15 (including the load resistor 16) and the second conductor 7. Connected to the positive pole of the first DC power supply 5 via
The output voltage of the first DC power supply 5 is applied to the charge / discharge capacitor 9 to accumulate charges. Further, the negative side ball electrode 13a of the gap switch 13 is connected to the negative side portion (including the coil 12) of the third conductor 11 and the first conductor 6 (the first conductor 6).
(Including a protective resistor 8) and the negative pole of the first DC power supply 5, and the plus-side spherical electrode 13b of the gap switch 13 is connected to the plus-side portion of the third conductor 11 and the second conductor 7
, The voltage applied to the gap switch 13 rises rapidly in parallel with the accumulation of charges in the charge / discharge capacitor 9.

At approximately the same time as the electric charge is substantially accumulated in the charge / discharge capacitor 9 up to the saturation state, a spark discharge occurs between the two ball electrodes 13a and 13b of the gap switch 13. This spark discharge causes the gap switch 13 to be in a short-circuit state or a conductive state, so that the negative electrode 9a of the charging / discharging capacitor 9 is short-circuited to the ground portion (or the positive pole of the first DC power supply 5). As a result, the electric charge stored in the charge / discharge capacitor 9 is released almost instantaneously, and this electric charge is transferred to the electrostatic capacity of the charge / discharge capacitor 9, the electrostatic capacity of the coupling capacitor 10, and the electrodes 1, 2
The voltage value determined by the ratio of the capacitance of the gap between the coil 12 and the coil 12
And a pulse voltage having a waveform determined by the resistance value of the load resistor 16 and applied between the discharge electrode 1 and the counter electrode 2.

Such a process is repeated, and a high-frequency pulse voltage is applied between the electrodes 1 and 2. Here, the first protection resistor 8 prevents the positive and negative poles of the first DC power supply 5 from being short-circuited when the gap switch 13 is in a short-circuit state or a conductive state, and thus the first DC power supply 5 It is provided to protect the power supply 5. The structure of a pulse voltage generation circuit that generates a pulse voltage from a DC voltage of a DC power supply using a gap switch is disclosed in Japanese Patent Application Laid-Open No. 7-235362 of the present applicant.

In the stationary DC voltage generating circuit C ₂ , the positive pole of the second DC power supply 17 is connected to the fifth conductor 18 (second
Is connected to P ₅ points of the first conductor 6 via including) the protective resistor 20, the negative pole of the second DC power supply 17 is the sixth conductor 19
Is connected to the point P _{6 of} the second conducting wire 7, the potential of the positive pole of the second DC power supply 17 is applied to the discharge electrode 1, and the potential of the negative pole of the second DC power supply 17 is
Is applied to That is, between the electrodes 1 and 2, a pulse voltage generated by the pulse voltage generating circuit C _1, the discharge voltage steady state DC voltage and is formed by superimposing produced by constant DC voltage generating circuit C ₂ is applied Will be.

Here, the peak value of the discharge voltage to be applied in order to generate a corona discharge between the electrodes 1 and 2 is determined by the distance between the electrodes 1 and 2 (hereinafter referred to as “distance between electrodes”). Although it depends, it is preferably about 10 to 300 KV, more preferably 20 to 200 KV.
The number of pulses of the discharge voltage, that is, the repetition frequency of the pulse voltage is preferably about 20 to 5000 pps, and more preferably 100 to 2000 pps. The pulse width of the discharge voltage, that is, the pulse width of the pulse voltage is preferably about 1 to 10 μm,
More preferably, it is μm. Further, the distance between the electrodes is preferably about 30 cm when the object 3 having various shapes or dimensions is subjected to the reforming treatment (plasma treatment). The peak value of the discharge voltage required in this case is, for example, about 200 KV.

Thus, according to the surface modification apparatus T1 or the surface modification method according to the first embodiment of the present invention, the discharge voltage for inducing a corona discharge between the electrodes 1 and 2 is changed to the pulse voltage. a pulse voltage generated by the generating circuit C _1, since so as to generate by superimposing a constant DC voltage generated by the constant DC voltage generating circuit C _2, not so high a pulse voltage or constant direct voltage However, a high-voltage (peak value) and high-frequency discharge voltage capable of performing a sufficient plasma treatment or corona discharge treatment on the workpiece 3 can be obtained. Therefore, the output voltage of the first DC power supply 5 for generating a pulse voltage or the output voltage of the second DC power supply 17 for generating a steady DC voltage can be reduced.

For this reason, the insulation mechanism of the pulse voltage generation circuit C ₁ including the first DC power supply 5 and the steady DC voltage generation circuit C ₂ including the second DC power supply 17 can be simple or small. Can be used as the circuit elements constituting the circuits C ₁ and C ₂ , the structure of the surface reforming apparatus T1 can be simplified or made compact, and the manufacturing cost can be reduced. Is done. That is, the workpiece 3 can be subjected to the surface modification treatment by plasma at low cost.

Hereinafter, a surface modification treatment apparatus T according to the present invention will be described.
1 will be described more specifically in comparison with a conventional surface modification treatment apparatus of this type. For example, FIG.
As (b), in this type of conventional surface modification apparatus T1 ', the constant DC voltage generating circuit C _2, such as a surface modification apparatus T1 according to the first embodiment of the present invention, the coupling capacitor 10 that assumes the existence of a circuit C ₂
And not equipped. In FIG. 1B, FIG.
Elements or members common to those in FIG. 1A are denoted by the same reference numerals as those in FIG.

[0030] Therefore, as shown in the graph of the left half portion in FIG. 3, in the conventional surface modification apparatus T1 ', the discharge voltage is only a pulse voltage Vp generated by the pulse voltage generation circuit C ₁ Will be covered. In this case, for example, if the distance between the electrodes is 30 cm, in order to perform a sufficient plasma processing on the workpiece 3, the peak value is about 200 KV.
It is necessary to apply the pulse voltage between the electrodes 1 and 2. To obtain such a pulse voltage, it is necessary to increase the output voltage of the first DC power supply 5 to approximately 180 KV. For this reason, an insulating mechanism and a circuit element that can withstand a high voltage are required, which leads to an increase in the size of the surface reforming apparatus T1 'and an increase in the manufacturing cost.

On the other hand, as shown in the graph in the right half of FIG. 3, in the surface modification apparatus T1 according to the first embodiment of the present invention, the discharge voltage is changed to the pulse voltage generation circuit C _1.
Is generated by superimposing the pulse voltage Vp ′ generated by the above and the steady DC voltage Vdc generated by the steady DC voltage generation circuit C ₂ , so that the discharge voltage becomes (Vp ′ + Vdc). Here, the discharge voltage (Vp '
If + Vdc) is made equal to the discharge voltage Vp in the conventional surface modification treatment device T1 ', almost the same corona discharge can be caused between the electrodes 1 and 2.

In this case, the voltage value Vp '(peak value) of the pulse voltage in the surface modification apparatus T1 according to the first embodiment is considerably lower than the discharge voltage Vp in the conventional surface modification apparatus T1'. Become. For example, as in the case of the conventional surface modification treatment apparatus T1 ', when the distance between the electrodes is 30 cm and the discharge voltage is 200 KV, if the steady DC voltage is set to 85 KV, the pulse voltage Vp' (wave High) is 115 KV, the first in this case
It is assumed that the output voltage of the DC power supply 5 is about 100 KV. As described above, since the output voltage of the first DC power supply 5 can be reduced, the insulating mechanism or circuit element does not need to be able to withstand such a high voltage, and the structure of the surface reforming apparatus T1 is simplified. Or compact, and its manufacturing cost is reduced. In other words, since the output voltage of the first DC power supply 5 of the pulse voltage generation circuit C ₁ can be low, the insulation design in the first DC power supply 5 or the pulse voltage generation circuit C ₁ can be facilitated, and the steady DC voltage generation circuit be subtracted new cost of C _2, a sufficient cost reduction is achieved, and miniaturization of the surface modification apparatus T1 is achieved.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described with reference to FIG. However,
The basic configuration of the surface modification processing apparatus T2 according to the second embodiment is the same as that of the surface modification processing apparatus T1 according to the first embodiment shown in FIG. 1A. The points that are different from the first embodiment will be mainly described. In FIG. 2, the same elements or members as those in FIG. 1A are denoted by the same reference numerals as those in FIG. 1A, and description thereof will be omitted.

As shown in FIG. 2, the pulse voltage generating circuit C ₁ ′ of the surface modification apparatus T 2 according to the second embodiment includes a first electrode connected to the positive electrode of the first DC power supply 5 and the discharge electrode 1. A first connection conductor 21 and a second connection conductor 22 for connecting the negative electrode of the first DC power supply 5 to the counter electrode 2 are provided. Then, the first protection resistor 8, the coil 12 (inductance), and the gap switch 13 are sequentially connected to the first connection conductor 21 from the first DC power supply 5 side toward the discharge electrode 1 side.
And a coupling capacitor 10 are provided in series.

Then, the S ₁ point of the first connection lead 21 and the second
An auxiliary capacitor 24 for assisting the charge / discharge capacitor 9 is provided on a third connection conductor 23 connecting the connection conductor 22 to the point S _2.
Are interposed as needed. In addition, the S ₂ point of the second connection conductor 22 is connected to the ground part 14. A charge / discharge capacitor 9 is interposed in the fourth connection conductor 25 connecting the point S ₃ of the first connection conductor 21 and the point S ₄ of the second connection conductor 22. Further, a load resistor 16 is provided on the fifth connection conductor 26 connecting the point S ₅ of the first connection conductor 21 and the point S ₆ of the second connection conductor 22.

On the other hand, the stationary DC voltage generation circuit C ₂ ′ is connected to the S ₁ point and S ₁ of the first connection conductor 21 of the pulse voltage generation circuit C ₁ ′.
It is composed of a sixth connection conductor 27 connecting the _seven points and a second protection resistor 20 (a DC superimposition protection resistor) provided on the sixth connection conductor 27, and does not have its own DC power supply. .
That is, in the second embodiment, the pulse voltage generation circuit C ₁ ′
The first DC power supply 5 also serves as a DC power supply for the steady DC voltage generation circuit C ₂ ′.

That is, in the second embodiment, a single first DC power supply 5 supplies a DC voltage necessary for generating a pulse voltage and a steady DC voltage. In the first embodiment shown in FIG. 1A, the first DC power supply 5
And a negative DC voltage output type that outputs a negative voltage to the first conducting wire 6 that connects the first conducting wire 6 to the first conducting wire 6.
Is a positive voltage output type that outputs a positive voltage to the fifth conductive line 18 that connects the first DC power supply to the pulse voltage generation circuit C ₁ ′. Output format. This is because, in the second embodiment, the positional relationship between the charge / discharge capacitor 9 of the pulse voltage generation circuit C ₁ ′, the coil 12 and the gap switch 13 is reversed from that of the first embodiment. . As a result, a positive pulse is applied to the discharge electrode 1, so that the pulse voltage and the steady DC voltage have the same polarity, and both voltages can be superimposed.

Thus, in the surface modification processing apparatus T2 according to the second embodiment, similarly to the surface modification processing apparatus T1 according to the first embodiment, the pulse voltage generation circuit C including the first DC power supply 5 is used. The insulation mechanism of the ₁ ′ and the steady DC voltage generation circuit C ₂ ′ can be simple, and the circuit elements constituting these circuits C ₁ ′ and C ₂ ′ can be relatively low withstand voltage. Therefore, the structure of the surface modification treatment device T2 can be simplified or compacted,
The manufacturing cost is reduced. Furthermore, since there is no need to provide an independent DC power supply for the steady DC voltage generation circuit C ₂ ′, the structure of the surface modification treatment device T2 is further simplified or compacted, and the manufacturing cost is further reduced.

[0039]

EXAMPLES Hereinafter, results obtained by actually performing a plasma treatment on an object to be processed using the surface modification processing apparatus T1 according to the first embodiment will be described. [Visual Confirmation of Discharge Intensity] When only the pulse voltage is applied (stopping the application of the steady DC voltage) using the surface modification apparatus T1 according to the first embodiment, the pulse voltage, the steady DC voltage and The plasma intensity due to the corona discharge was visually observed in the case where the voltage was superimposed and applied.
If the plasma generated by the corona discharge has substantially the same brightness, it is considered that the surface modification treatment effect (plasma treatment effect) is almost the same.

When there is no dielectric (object to be processed) on the opposing electrode (the gap between the two electrodes), only the pulse voltage Vp is applied as the discharge voltage Vt (Vdc = 0), When the discharge voltage Vt is equal to the case where the combined voltage (Vp + Vdc) is superimposed on the DC voltage Vdc and the composite voltage (Vp + Vdc) is used as the discharge voltage Vt, it has been confirmed that a sufficiently strong corona discharge can be obtained. From this result, it is presumed that when the discharge voltage Vt is equal, almost the same plasma processing can be performed when only the pulse voltage is applied and when the pulse voltage and the steady DC voltage are superimposed. .

Table 1 shows that a dielectric (object to be processed) was formed on the counter electrode.
The results of observations in the case where are arranged are shown. In this observation experiment, the distance between the electrodes was 50 mm, and the thickness of the dielectric was 3 mm.
mm. In Table 1, the results of the visual observation (evaluation) are evaluated on a five-point scale, and the larger the “*” mark, the stronger the plasma. In the following, "*"
Is n-th stage. Therefore,
In the case of the first stage (*), the plasma is the weakest, and in the case of the fifth stage (****), the plasma is the strongest (in Table 1, there is no fifth stage). .

[0042]

[Table 1]

As shown in Table 1, the evaluations of the sample No. 1 and the sample No. 5 in which the discharge voltage Vt is substantially the same were in the third stage (***), but the evaluation was in the third stage (***). The brightness of the plasma of Sample No. 5 (DC superimposed) on which the DC voltage was superimposed was higher than that of Sample N on which only the pulse voltage was applied
The result obtained was slightly weaker than that of the plasma of O.1. However, steady DC voltage (Vdc)
As the sample No. 2 in which the steady DC voltage Vdc was increased to 13 KV, a sufficiently bright plasma was obtained. According to this result, it is estimated that when the discharge voltage Vt is approximately equal, almost the same plasma processing can be performed when only the pulse voltage is applied and when the pulse voltage and the steady DC voltage are superimposed. Is done.

[Confirmation of Processing Effect by Pilot Apparatus]
FIG. 4 shows the results of measuring the water contact angle of the plastic plate surface after plasma treatment on the plastic plate surface in order to confirm the effect of improving the hydrophilicity on the plastic plate surface. The smaller the water contact angle, the higher the hydrophilicity improving effect. This plasma treatment is a continuous treatment, and a plastic plate (M4800 Mlastomer manufactured by Mitsui Petrochemical) is used as the object to be treated. The number of discharge electrodes is 5 slits, the distance between the electrodes is 60 cm, and the passing speed of the object to be processed is 0.8 m /
min.

As shown in FIG. 4, the discharge voltage Vt (Vp for only the pulse voltage, Vp + Vd for the superimposed voltage)
When c) is the same, the case of only the pulse voltage is
The water contact angle is smaller than in the case of the superimposed voltage (the superposition of the pulse voltage and the steady DC voltage), so that a higher hydrophilicity improving effect is obtained. Therefore, from the viewpoint of the effect of improving hydrophilicity, it can be seen that the processing effect is slightly lower in the case of the superimposed voltage than in the case of the pulse voltage alone. However, even in the case of the superimposed voltage, if the steady DC voltage Vdc is increased, it is presumed that a sufficient hydrophilicity improving effect can be obtained even when the pulse voltage is relatively low (150 KV).

As described above, in order to obtain the same processing effect as the case of using only the pulse voltage by the superimposed voltage method, it is necessary to increase the steady DC voltage. However, according to the result shown in FIG. In order to obtain the same processing effect as the case of performing the plasma processing using only the pulse voltage by the superimposed voltage method, if the pulse voltage Vp is set to 150 KV, the steady DC voltage Vdc needs to be set to 65 to 70 KV. .

[Embodiment of DC superimposition system using one DC power source]
FIG. 5 shows the surface modification apparatus T2 according to the second embodiment shown in FIG. 2, that is, the DC power supply 5 of the pulse voltage generation circuit C ₁ ′ also serves as the DC power supply of the steady DC voltage generation circuit C ₂ ′ (for superposition). The figure shows the results obtained by subjecting an object to be treated to plasma treatment using a surface modification treatment apparatus T2 (in which a power source is integrated) and measuring the water contact angle of the object to be treated after the treatment. In addition,
The processing conditions or experimental conditions for each sample are described in FIG. In the surface modification apparatus T2 according to the second embodiment, the output voltage of one DC power supply 5 serves as both a DC voltage for generating a pulse voltage and a steady DC voltage. For this reason, in this measurement, the pulse voltage is raised by changing the number and length of the slits of the discharge electrode to reduce the amount of discharge generated. Therefore, when the number of slits is changed, the processing conditions are made the same, for example, by making the number of processing passes of the processing object equal in total.

As shown in FIG. 5, in the plasma processing by the surface modification processing apparatus T2 according to the second embodiment, if the discharge voltage Vt is the same, there is almost no difference between the case of only the pulse voltage and the case of the superimposed voltage. It can be said that the same hydrophilicity improving effect is obtained.

Table 2 shows that the current large-sized plasma device is assumed to be a conventional type (only pulse voltage is applied).
The results of cost calculation are shown for the case of manufacturing with the superimposed voltage method and the case of manufacturing with the superimposed voltage method. As shown in Table 2, in the superimposed voltage system of the type in which two DC power supplies according to the first embodiment are provided, the production cost is 30 times less than that of the conventional system.
% Has been reduced. Further, in the superimposed voltage system of the type in which only one DC power supply according to the second embodiment is provided, the manufacturing cost is reduced by 50% as compared with the conventional system. Therefore, it can be seen that the manufacturing cost of the surface modification treatment device according to the present invention is significantly reduced.

[0050]

[Table 2]

The surface reforming apparatus T according to the first embodiment
1, the factor that can reduce the cost in this way is that the output voltage of the first DC power supply 5 for generating the pulse voltage can be set to 150 KV or less, thereby lowering the insulation design by one grade. What you can do (insulation class 80
From No. 60 to No. 60) in that the power consumption for generating the pulse voltage can be reduced. On the other hand, increase in cost, in order to provide a constant DC voltage generating circuit C ₂ for superimposing a constant DC voltage, the second DC power source 1
7. Coupling capacitor 10 and second protection resistor 20
It is necessary to add. However, Table 2
According to the above, it is shown that the effect of cost reduction is greater than the cost increase. For example, it has been confirmed that the DC power supply cost of 9.3 million yen in the conventional circuit configuration is reduced to 3.7 million yen in the first embodiment, which is about a 60% cost reduction. Then, even if the second DC power supply 17 and the coupling capacitor 10 are added, it is estimated that the cost can be reduced by a total of 30% due to the merits of lowering the withstand voltage and lowering the insulation class. I have.

Further, in the surface reforming apparatus T2 according to the second embodiment in which the DC power supplies for the pulse voltage generation circuit and the steady DC voltage generation circuit are integrated, it is not necessary to add a DC power supply. Thus, the cost can be further reduced. This is because the power capacity of the second DC power supply (power supply for superimposition) is very small, and this power can be easily covered by the DC power supply for pulse voltage generation.

[Brief description of the drawings]

FIG. 1A is a circuit diagram illustrating a configuration of a surface modification processing apparatus according to a first embodiment of the present invention, and FIG. 1B is a circuit diagram illustrating a configuration of a conventional surface modification processing apparatus. .

FIG. 2 is a circuit diagram showing a configuration of a surface modification processing apparatus according to a second embodiment of the present invention.

FIG. 3 is a graph showing a change characteristic of a discharge voltage with respect to time of the surface modification processing device shown in FIG. 1A and a change characteristic of a discharge voltage with time of the surface modification treatment device shown in FIG. It is.

FIG. 4 is a graph showing the effect of improving the hydrophilicity of the plasma treatment by the surface modification treatment device according to the first embodiment in comparison with a conventional example.

FIG. 5 is a graph showing the effect of improving the hydrophilicity of the plasma treatment by the surface modification treatment device according to the second exemplary embodiment in comparison with a conventional example.

[Explanation of symbols]

T1 ... surface modification apparatus (Embodiment 1) (conventional example) T1 '... surface modification apparatus, T2 ... surface modification apparatus (Embodiment 2), C ₁ ... pulse voltage generating circuit, C ₁ '…
Pulse voltage generation circuit, C ₂ ... steady DC voltage generation circuit,
C ₂ ': steady DC voltage generating circuit, 1: discharge electrode, 2: counter electrode, 3: workpiece, 4: plasma, 5: first DC power supply (negative polarity), 5': first DC power supply (positive electrode) 6) 1st
Conductor, 7: second conductor, 8: first protection resistor, 9: charge / discharge capacitor, 10: coupling capacitor, 11: third
Conductor, 12: coil (inductance), 13: gap switch, 14: grounding part, 15: fourth conductor, 16 ...
Load resistance, 17: second DC power supply (positive polarity), 18: fifth
Conductor, 19 ... sixth conductor, 20 ... second protection resistor, 21 ... first connection conductor, 22 ... second connection conductor, 23 ... third connection conductor, 24 ... auxiliary capacitor, 25 ... fourth connection conductor, 26
... Fifth connection conductor, 27 ... Sixth connection conductor.

Continued on the front page (72) Inventor Kensuke Akutsu 19-17 Ikedanakacho, Neyagawa-shi, Osaka Inside Nippon Paint Co., Ltd. F term (reference) 4D075 BB49X BB99X CA12 CA35 CA37 CA40 DA04 DB18 DB20 DB31

Claims (8)

[Claims] 1. A high-voltage discharge voltage is applied between a discharge electrode and a counter electrode facing each other to generate corona discharge in a gap between the two electrodes to generate plasma, and to process the gap between the two electrodes. In a surface modification treatment method in which an object is arranged to modify the surface characteristics of the object to be treated by the plasma, the discharge voltage is generated by superimposing a pulse voltage and a steady DC voltage. A surface modification treatment method comprising: 2. The surface reforming method according to claim 1, wherein the pulse voltage is generated by performing a gap discharge of a DC power supplied from a DC power supply. 3. The method according to claim 2, wherein the output voltage of the DC power supply is set to 200 KV or less, and the steady DC voltage is set to 100 KV or less. 4. The system according to claim 2, wherein said DC power supply is used as a power supply for said steady DC voltage.
3. The surface modification treatment method according to item 1. 5. A discharge electrode comprising: a discharge electrode; a counter electrode disposed to face the discharge electrode; and high voltage applying means for applying a high discharge voltage between the electrodes. Means for applying the discharge voltage between the two electrodes, generating a plasma by inducing a corona discharge in the gap between the two electrodes, and applying the plasma to the surface characteristics of the object disposed in the gap between the two electrodes. In the surface reforming apparatus adapted to be reformed, the high voltage applying means overlaps the pulse voltage between the two electrodes with a pulse voltage applying means for applying a pulse voltage between the two electrodes. A surface reforming apparatus comprising: a steady DC voltage applying means for applying a steady DC voltage. 6. The pulse voltage applying means includes a DC power supply, and a gap discharge switch circuit for converting a DC voltage supplied from the DC power supply to a pulse voltage and applying the pulse voltage between the two electrodes. The surface modification treatment device according to claim 5, wherein: 7. The surface reforming apparatus according to claim 6, wherein the output voltage of the DC power supply is 200 KV or less, and the steady DC voltage is 100 KV or less. 8. The surface reforming apparatus according to claim 6, wherein the DC power source also serves as a power source for the steady DC voltage applying means.