JPH07196827A - Modifying method for surface of polymer material - Google Patents

Abstract

PURPOSE:To treat an arbitrarily selected part or the whole of the inside surface of a tubular object selectively, uniformly, and simply at a low cost without fail and without deforming the shape of the object. CONSTITUTION:At least one corona discharge electrode 11 is installed inside a tubular object 12 made of a polymer material, and at least one counter electrode 13 for corona discharge, outside the object 12. The inside surface of the object 12 is treated by causing the discharge electrode 11 to discharge toward the counter electrode 13. The counter electrode 13 is formed by coating the outside of the object 12 with a conductive substance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface modification method by corona discharge as a pretreatment of a tube-shaped surface of a relatively inert polymer material, for example, adhesiveness, paint or printing. It is a method used to improve the adhesiveness of the like.

[0002]

2. Description of the Related Art Generally, the surface of an object to be treated is modified as a pretreatment for imparting a function such as adhesiveness or paintability of a solid surface.
Application of modifiers, oxidation treatment, flame discharge, corona discharge, graft polymerization of different monomers, glow discharge, ultraviolet irradiation, etc. are known. Among them, corona discharge is used in various fields of industrial production equipment because the device configuration is simple and surface treatment can be performed in a short time without special proficiency.

At present, a large number of discharge electrodes of a corona discharge device having a cylindrical shape or a ball-shaped end portion are used. On the other hand, in corona discharge, when the object to be treated has a two-dimensional shape, the treatment is easy, but the inner surface treatment of the object to be treated having a three-dimensional shape is not so easy. Therefore, conventionally, as a method for treating an object having such a three-dimensional shape, Japanese Patent Laid-Open No. 64-248 has been proposed.
36, Japanese Patent Publication No. 3-59094, Japanese Patent Publication No. 3-59095, and the like.

In the invention disclosed in Japanese Patent Laid-Open No. 64-24836, the discharge electrodes facing the inside and outside of the object to be processed are provided, and the outside of the object to be processed is filled or pressure-contacted with an electrically resistive substance. Corona discharge is generated from the inner electrode to the outer electrode to treat the inside of the object to be treated. In addition, Japanese Patent Publication No. 3-59094 and Japanese Patent Publication No.
The invention disclosed in Japanese Patent Application No. 59095 is closely opposed to a back surface of a processing object having a three-dimensional shape, and includes a protective layer, a conductive layer, and a base material having the same shape as the back surface of the processing object. An electrode is formed so that the inner wall of the through hole of the object to be treated can be treated. In particular, the conductive layer is formed by spraying on the back side of the object to be processed by the metal spraying method.

[0005]

However, in the method described in Japanese Patent Laid-Open No. 64-24836, a liquid having a high electric resistance is poured into a container which is an object to be treated to form a counter electrode. In addition, a roller made of an electric resistance material is pressed against the object to be processed to form a counter electrode. Therefore, for example, for a workpiece that is long in the axial direction, such as a tube shape, or is open at both ends, inject a liquid with high electrical resistance into the workpiece to form a counter electrode. It was difficult to dispose the roller-type counter electrode inside or outside the tube when the tube shape having a small size was used as the object to be processed.

Further, in the methods described in Japanese Patent Publication No. 3-59094 and Japanese Patent Publication No. 3-59095, the object to be processed has a tube shape because it is necessary to closely attach the counter electrode to the back side of the object to be processed. In that case, the workability was poor. Further, since a conductive metal is sprayed on the back side of the object to be processed by using the metal spraying method, it is necessary to work in a high temperature state. At that time, when the object to be processed is a polymer material, the polymer material may be damaged by heat such as melting, and it is difficult to maintain the shape of the object to be processed. Further, in any of the above conventional techniques,
The area of the discharge part to be processed by the discharge electrode may be wide, but if the object to be processed is a tube shape and the diameter is small, the ball electrode cannot be used because the object to be processed is thin, When the discharge electrode has a thin wire shape, discharge is randomly generated from various parts of the electrode, and it is difficult to perform uniform treatment.

The present invention has been made in view of the above-mentioned conventional problems, and the shape of the object to be processed is maintained while maintaining the shape of the object to be treated on a part or the whole of the inner surface of the object having a tube shape. It is an object of the present invention to provide a surface modification method for a polymer material, which enables selective and uniform treatment, is simple, reliable, and can be treated at low cost.

[0008]

In order to solve the above-mentioned problems, the present invention provides a corona discharge treatment discharge electrode for corona discharge treatment on the inside of an object to be treated which is made of a polymer material in the shape of a tube. Polymer by a corona discharge treatment method for treating the inner surface of the object to be treated in the tube shape by disposing at least one counter electrode for each of the electrodes and discharging from the inner discharge electrode toward the outer counter electrode. In the surface modification method of the material, the outer counter electrode is formed by coating the outer surface of the tube-shaped object to be processed with a conductive substance. Here, as the discharge electrode for corona discharge treatment provided inside the tube-shaped object to be treated, an electrode formed by forming a discharge portion including at least one acute-angled protrusion on a conductive object such as a stainless rod is used. Good.

That is, the present invention relates to a corona discharge treatment apparatus in which an outer surface of an object to be treated having a tube shape is coated with a conductive substance by vapor deposition or coating to form a counter electrode and a discharge electrode is arranged inside. using,
It employs means for performing corona discharge treatment on the inner surface of the object to be treated. Then, in order to remove the conductive counter electrode layer on the outer surface of the object to be processed, if necessary, the object to be processed may be put into a weak acid solution.

As the conductive material of the counter electrode, aluminum, copper, silver, gold, silver paste or a polymer material doped with a donor or an acceptor can be used. , And the opposite electrode. As the shape of the discharge portion of the inner discharge electrode, a shape having a plurality of acute-angled portions such as a star shape and a cubic shape may be used.

[0011]

The present invention operates as follows by adopting the above means. The counter electrode for corona discharge treatment in the present invention can be formed by selectively coating only a desired portion of the object to be treated by masking a portion of the object not to be treated with corona discharge with a tape or the like. . Therefore, at the time of corona discharge treatment, instead of treating random parts of the object to be treated, only the treatment part on the back side of the counter electrode part which is selectively coated on the object to be treated is uniformly subjected to corona discharge treatment. be able to. Further, when the counter electrode layer is coated on the object to be processed, it is possible to perform work at a low temperature such as vapor deposition or application of a conductive substance, so that the polymer material as the base material may be damaged by heating. Absent. Furthermore, when silver paste or conductive polymer is used as the conductive material of the counter electrode,
Since the conductive material has a weak adhesive strength to the object to be processed, it can be peeled off into a soft and tough film, and the counter electrode layer can be easily removed in a later step.

Further, in the silver paste which is a conductive substance used in the present invention, silver having the lowest electric resistance is usually applied to an epoxy resin or a silicone condensation resin which is an electric insulator to obtain a silver paste. It has the same effect as when using only. In the case of using a conductive metal, the conductive polymer itself has a low electric conductivity, but the electric conductivity becomes about 10 3 scm -1 by doping with a donor or an acceptor. Has the same effect as. In addition, in a general discharge phenomenon, electric charges are concentrated on a portion having a small tip diameter and are easily discharged. Therefore, a discharge electrode having a discharge portion provided with at least one acute-angle-shaped protrusion is used to charge the tip of the protrusion. Concentrates.
Therefore, corona discharge treatment can be performed only from the discharge part of the discharge electrode. Further, by moving the discharge electrode, it is possible to perform a uniform corona discharge treatment over the entire treatment area.

[0013]

Example 1 (Structure) FIG. 1 shows Example 1 of a surface modification method of a polymer material by a corona discharge treatment method. The object to be treated 12 is made of polytetrafluoroethylene (hereinafter referred to as PTFE) having a tube shape with both ends open, and has an inner diameter of 5 mm. The processing surface is up to 3 cm from the opening. As the discharge electrode 11, a stainless wire having a diameter of 2 mm and a length of 4 cm was used. However, theoretically, it is not limited to this length. The corona discharge generating portion is located in the vicinity of the opening end surface of the object to be processed 12. Counter electrode 13
Was produced by vapor-depositing conductive copper on the outside of the object to be treated 12. At the time of vapor deposition, a tube-shaped opening was filled with a spherical metal having a diameter of 8 mm so that the inside of the object to be treated 12 was not treated, and vapor deposition was performed twice on the front and back in order to uniformly vaporize the entire treated portion. . 1 and subsequent figures, in order to show the main principle of the corona discharge treatment method according to the present invention, a mechanism and a corona for fixing, rotating and moving the discharge electrode, the counter electrode and the object to be treated. A power supply, an operation unit and the like of the electric discharge treatment device are omitted and shown as a model.

Using the above configuration, processing power of 30 Wa
Corona discharge was performed on the object to be treated 12 at tt for a treatment time of 8 seconds. Further, in order to uniformly and efficiently process the entire inner surface of the object to be processed 12, the object to be processed 12 was rotated twice during the corona discharge treatment. After the corona discharge treatment,
If necessary, the weak acid solution was wiped off with a moistened sillbon paper to remove the vapor-deposited layered counter electrode 13.

(Operation) In this embodiment, the object to be treated 12
Has a tube shape with both ends open, and since the conductive metal copper is uniformly vapor-deposited over the entire treated surface to form the counter electrode 13, the entire treated surface of the object 12 is subjected to corona discharge treatment. Further, since the object to be treated 12 is rotated, the treated surface is efficiently subjected to corona discharge treatment.

(Effect) In the corona discharge treatment of this embodiment, the object to be treated 12 having a tube shape with both ends opened.
Even in the vicinity of the end face of the opening, the treatment can be performed reliably, uniformly and efficiently.

[0017]

Second Embodiment (Structure) FIG. 2 shows a second embodiment of the surface modification method of the polymer material by the corona discharge treatment method. The object to be processed 22 is made of polyethylene having a tube shape with both ends open. The counter electrode 24 was formed by coating the outside of the object to be processed 22 with conductive copper, and at the time of coating, the inside of the object to be processed 22 was masked as described in Example 1. In order to selectively process the object 22 to be processed, the counter electrode 24 is masked with a tape at the time of coating, and an unprocessed portion 23 is provided at the tip of the object 22 to be processed.

The discharge electrode 21 is made of stainless steel and has a shape in which a discharge portion 26 composed of a plurality of acute-angled projections is provided at the tip portion. An example of the shape used as the discharge portion is shown in FIG.
Shown in. The discharge electrodes 41 to 45 are made of stainless steel, and discharge parts 47 to 51 are attached to the discharge part at the tip for uniformly and efficiently discharging the entire processing part. The discharge part 47 is a cube, and the discharge part 48 is a dodecahedron.
The aluminum foil was processed into a shape having a plurality of protrusions. The discharge part 49 has a star shape with four vertices, the discharge part 50 has a star shape with five or more vertices, and the discharge part 51 has a plurality of projections formed by bifurcating the tip of the wire which is the discharge electrode 45 by about 2 mm. The shape has a part.

Further, in this embodiment, in order to prevent wasteful discharge from portions other than the discharge part 26, as shown in FIG. 2, a portion 25 of the discharge electrode 21 is coated with PTFE made of an insulating material. The workpiece 22 has an inner diameter of 5 mm. The length of the treated surface is 2 cm from the opening. Discharge electrode 21
Enters the inside of the object to be processed 22 described above, so φ2 mm,
A wire with a length of 3 cm was used. However, theoretically, it is not limited to this length.

Using the above configuration, processing power of 30 Wa
The corona discharge treatment was performed on the object to be treated 22 at tt for a treatment time of 8 seconds. Further, in order to uniformly and efficiently process the inner surface of the object 22 to be processed, a device for rotating and moving the object 22 to be processed by a motor is provided (not shown).
As a result, the inside of the object to be processed 22 rotates twice, and the processing section makes two reciprocations in about 8 seconds. After the corona discharge treatment,
If necessary, the coated counter electrode 24 was removed with sillbon paper soaked with a weakly acidic solution.

(Function) By the discharge electrode 21 and the counter electrode 24 having the uncoated portion 23, the object 2 to be treated is
Corona discharge treatment is selectively applied to the inner surface of No. 2 other than near the opening. Moreover, since the discharge electrode 21 provided with the discharge part 26 having a plurality of acute-angled protrusions is used, the discharge is concentrated from the tip of the protrusions, and the object 22 to be treated is uniformly and selectively subjected to the corona discharge treatment. To do. Further, the processed portion 22
Since the object is rotated and moved, the treatment section is efficiently subjected to corona discharge treatment.

(Effects) In the corona discharge treatment of this embodiment, the position where the copper is coated on the object to be treated 22 is manipulated, the discharge electrode 21 provided with the discharge portion 26 having a plurality of protrusions is used, and By rotating and moving the treated portion 22, the corona discharge treatment can be performed more selectively, reliably and efficiently even in the vicinity of the opening of the treated object 22.

[0023]

Third Embodiment (Structure) FIG. 4 shows a third embodiment of the surface modification method of the polymer material by the corona discharge treatment method. The configurations of the object to be processed 32 and the counter electrode 34 are the same as those in the second embodiment. The discharge electrode 31 is
It is made of stainless steel, and has a shape in which a discharge portion 36 having a plurality of acute-angled protrusions of about 2 mm is provided at an arbitrary portion of the tip portion and the outer circumference. In addition, in order to prevent unnecessary discharge from parts other than the discharge part 36, PTFE made of an insulating material is applied to the parts 35 other than the discharge part 36. The object 32 to be processed is a polymer material having a tube shape with both ends open, and has an inner diameter of 6 mm. The length of the processing surface is 2
cm. Since the discharge electrode 31 enters the inside of the object 32 to be treated, a wire having a diameter of 3 mm and a length of 3 cm was used.
However, theoretically, it is not limited to this length.

Utilizing the above configuration, processing power of 20 Wa
The corona discharge treatment was performed on the object to be treated 32 at tt for a treatment time of 10 seconds. After the corona discharge treatment, the coated counter electrode 34 was removed with sillbon paper impregnated with a weakly acidic solution, if necessary.

(Function) By the discharge electrode 31 and the counter electrode 34 having the uncoated portion 33, the object 2 to be treated is
Corona discharge treatment is selectively applied to the inner surface of No. 2 other than near the opening. Further, since the discharge electrode 31 having the discharge part 36 including a plurality of protrusions is used, the discharge is concentrated from the tip of the protrusion, and uniform and selective corona discharge treatment is performed.

(Effect) In the corona discharge treatment of this embodiment, the object 32 to be treated is operated at the position where it is coated with copper, and the discharge electrode 31 having a plurality of protrusions at any portion is used. It is possible to perform the corona discharge treatment more selectively, surely, and efficiently in a region other than the vicinity of the opening of the workpiece 32 without moving the workpiece 32.

[0027]

Fourth Embodiment (Structure) In the second embodiment, a metal other than copper is used as a conductive metal and is vapor-deposited on an object to be processed to form a counter electrode. The metal shown in Table 1 was used as the conductive metal. Also,
The electrical resistivity of each metal is also shown in the table.

[0028]

[Table 1]

(Operation) The same operation as in the second embodiment is obtained by the structure of the second embodiment and vapor deposition of the conductive metal on the object to be processed to form the counter electrode.

(Effect) The corona discharge device according to the present embodiment can use a conductive metal other than copper and is provided with a counter electrode layer suitable for the characteristics of the object to be treated, so that a more efficient corona discharge treatment can be achieved. it can. Regarding the conductive metal, silver or gold can be easily deposited on the object to be processed. Further, although aluminum has a larger electrical resistivity than silver or copper, aluminum is inexpensive, so that the cost can be suppressed.

[0031]

[Example 5] In Example 2, a condensing resin containing silver powder (hereinafter referred to as a silver paste) was used and applied to an object to be treated to form a counter electrode. For the silver paste, an epoxy resin containing silver powder or a silicone-based condensation resin containing silver powder was used.

(Operation) By applying the silver paste to the object to be processed, the same operation as in the second embodiment is produced.

(Effect) In the corona discharge treatment of this embodiment, the treated surface can be surely and efficiently subjected to the corona discharge treatment. Further, when the counter electrode layer is removed after the corona discharge treatment, the silver paste can be peeled off by scratching a part of the silver paste application portion in the counter electrode layer, which facilitates the work.

[0034]

[Sixth Embodiment] In the second embodiment, a conductive polymer whose electric conductivity is improved by doping a donor (n-type dopant) or an acceptor (p-type dopant) is applied to the outside of the object to be treated, It was used as an electrode. As the conductive polymer, one having a molecular structure in which a π-electron conjugated system as shown in Table 2 is greatly developed was used. Further, as shown in Table 3, a dopant having an electron transfer interaction with the conjugated polymer chain was used as the dopant. The method of doping the conductive polymer includes gas phase doping, liquid phase doping, electrochemical doping, ion implantation and the like. The conductive polymer doped by such various methods is applied to the outside of the object to be treated,
It can be used as a counter electrode.

[0035]

[Table 2]

[0036]

[Table 3]

(Function) The conductive polymer applied to the outside of the object to be treated has a low electric conductivity of the conductive polymer itself as the counter electrode, but the electric conductivity is increased by doping the donor or the acceptor. , Corona discharge treatment can be applied to the treated surface.

(Effect) In the corona discharge treatment of this embodiment, the treated surface can be surely and efficiently subjected to the corona discharge treatment. In addition, the counter electrode layer of the conductive polymer applied to the object to be treated is once applied to the object to be treated, and after the corona discharge treatment, the conductive polymer layer which is the counter electrode is cured. It can be reused by removing it so as not to destroy it.

(Comparative Example) FIG. 5 shows a comparative example of corona discharge treatment for a tube-shaped object to be treated by a conventional method not using the present invention. The discharge electrode 53 is bent in an L shape so as to be inserted inside the tube. The object to be processed 54 is
Only cross sections are shown for reasons of explanation. As the counter electrode 55, a counter electrode of an ordinary corona discharge device was used. In this corona discharge treatment method, the discharge concentrates on the bent portion or the tip portion of the discharge electrode 53 such as the corner portion 56 and the tip portion 57 of the discharge electrode 53, and the workpiece 54 near the portion melts. .
Therefore, it is impossible to perform uniform corona discharge treatment on the entire treated surface.

[0040]

As described above, according to the surface modification method of a polymer material of the present invention, when the inner surface of a treatment object having a tube shape is treated, the treatment object position and opening in the treatment object are processed. Regardless of the distance from the end face, the size of the object to be processed,
Regardless of the number, it is possible to selectively, easily, reliably, uniformly and efficiently perform an arbitrary part or whole of the object to be processed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a method according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a method according to a second embodiment of the present invention.

FIG. 3 is a front view showing an example of a discharge electrode according to the second embodiment.

FIG. 4 is a perspective view showing a method according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a conventional method.

[Explanation of symbols]

11, 21, 31, 41, 42, 43, 44, 45, 5
3 Discharge electrode 12, 22, 32, 54 Object to be treated 13, 24, 34, 55 Counter electrode 26, 36, 47, 48, 49, 50, 51 Discharge part

Claims (2)

[Claims] 1. At least one corona discharge treatment discharge electrode is provided inside a tube-shaped polymer material to be treated, and at least one counter electrode for corona discharge treatment is provided outside, and an inside discharge is provided. In the surface modification method of the polymer material by the corona discharge treatment method for treating the inner surface of the tube-shaped object to be treated by discharging toward the counter electrode outside the electrode, the outer counter electrode is a tube. A surface modification method for a polymer material, which is formed by coating the outside of a shaped object to be processed with a conductive substance. 2. An electrode in which a discharge part composed of at least one acute-angled protrusion is formed on a conductive object is used as the discharge electrode for corona discharge treatment provided inside the tube-shaped object to be treated. The method for modifying the surface of a polymer material according to claim 1.