JPH05339398A - Equipment for corona discharge treatment - Google Patents

Abstract

PURPOSE:To provide the title equipment which can prevent the occurrence of harmful spark discharge to ensure the treatment of a resin molding throughout to the edge, produces a marked effect of surface treatment on a resin molding, and can easily cope with a resin molding different in shape because of the simple structure of the electrodes. CONSTITUTION:The title equipment is provided with: a transfer conveyor 70, such as a roller conveyor, for transferring resin moldings 10; a counter electrode 20 arranged below the conveyor 70; a dielectric 60 that covers the surface of the electrode 20; a number of discharge electrodes 40 installed at a certain distance along the transfer path for the moldings 10 and facing the upper ends of the moldings 10 to conform to the shape of the end; and a high-voltage pulse generator 500 for applying a high-voltage pulse with a pulse width of at least 1mus, an average field strength, represented by applied voltage (crest value)/distance between electrodes, of 6-20kv/cm, and a pulse frequency of at least 10pps between the discharge electrode 40 and the counter electrode 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona discharge treatment device, and more particularly, to a corona discharge treatment device for improving the paintability, printability, and adhesiveness of resin molded products having various three-dimensional shapes. The present invention relates to an apparatus for performing surface treatment by electric discharge.

[0002]

2. Description of the Related Art It is well known that by applying corona discharge treatment to the surface of a resin film made of polypropylene or the like, it is possible to improve the printability and adhesiveness of the film surface, and it is used in the manufacture of various products. Not only the resin film, but also the surface of the resin molded product having a three-dimensional shape, that is, three-dimensional shape, is subjected to corona discharge treatment under normal pressure to improve the paintability and adhesiveness. There is.

In the conventional corona discharge treatment, a pair of electrodes consisting of a discharge electrode and a counter electrode is used, an object to be treated is placed between the pair of electrodes, and a high voltage is applied between the electrodes under normal pressure to cause corona discharge. Corona discharge treatment is applied to the surface of the object to be treated by generating electric discharge. At this time, as the high voltage applied between the electrodes, an AC high frequency voltage is usually used. It is said that the AC high-frequency voltage easily causes corona discharge and is excellent in the effect of surface treatment. In addition, Japanese Patent Laid-Open No. 4
Japanese Patent Laid-Open No. 7-4890 describes that the treatment effect is improved by using a high voltage pulse having a pulse width of about 100 to 200 μs for the corona discharge treatment on the film.

When the object to be treated is a resin molded product having a three-dimensional shape, it is required to perform good corona discharge treatment on the uneven surface, and there are various restrictions as compared with a flat film or plate material. Therefore, various improvement methods have been proposed. For example, Japanese Patent Laid-Open No. 57-119931 discloses that the tip position of the discharge electrode is always kept at a constant distance from the surface of the object to be processed held by the counter electrode. While relatively moving the counter electrode and the object to be treated and the discharge electrode, an AC high-frequency voltage is applied between the counter electrode and the discharge electrode to generate corona discharge, and the surface of the object to be treated is subjected to corona discharge treatment. A method is disclosed. In Japanese Patent Laid-Open No. 62-57431, a discharge electrode having a discharge tip having a curved shape is relatively moved along the surface of an object to be processed, and an AC high frequency output of 20 to 30 kHz is applied. A method of performing corona discharge treatment is disclosed.

However, in the corona discharge treatment method for resin molded products having these three-dimensional shapes, spark discharge is likely to occur, and sufficient treatment is applied to the edges existing on the outer periphery of the resin molded product or the inner periphery of the opening. There was a problem that it was difficult to apply. This is because in the conventional method, when the discharge electrode approaches the edge of the resin molded product, the distance between the discharge electrode and the counter electrode, that is, the so-called inter-electrode distance, becomes smaller, so that the corona discharge effective for surface treatment is stabilized. Therefore, it cannot be maintained, and a spark discharge occurs due to dielectric breakdown of the air layer. In order to prevent spark discharge, the applied voltage may be lowered, but then the corona discharge treatment effect cannot be sufficiently enhanced.

As a method for solving such a problem, Japanese Unexamined Patent Publication No. 62-57431 discloses that a buffer plate made of a dielectric material such as epoxy resin is fitted into the opening of a resin molded product and opened. A technique for preventing the corona discharge from being disturbed in the hole is disclosed. However, in this method, it is time-consuming to prepare a buffer plate corresponding to the shape of the opening portion of the resin molded product and attach this buffer plate to the predetermined position of the resin molded product or the counter electrode, resulting in work efficiency and electrode production. It has the drawback of being very inefficient. Further, if there is a slight gap between the aperture and the buffer plate, there is a problem that dielectric breakdown occurs through this gap and spark discharge is generated.

In order to solve the above-mentioned problems of the prior art, the inventors of the present application studied the waveform of the high voltage applied to the discharge electrode, and as a result, found that the peak value was 10 to 100 kv.
Pulse width is 1 μs or less, pulse frequency is 10 to 1000 pp
It was found that if a high voltage pulse s, which has an extremely narrow pulse width, is used, spark discharge is unlikely to occur, and good corona discharge is generated. A patent application has been filed in 3-98818.

[0008]

However, in the case of using the above-mentioned high-voltage pulse having an extremely narrow pulse width, the energy efficiency becomes extremely poor if the high-voltage pulse is applied in order to enhance the effect of the corona discharge treatment. Because it will
There is a drawback that the distance between electrodes cannot be increased. In the conventional method, the inter-electrode distance for which corona discharge treatment is practically possible is 3 to less than 5 cm, which is satisfactory when treating three-dimensional shaped articles having various shapes thicker than the inter-electrode distance. No results were obtained.

This is because a high voltage pulse having a pulse width of 1 μs or less as in the prior art can satisfactorily prevent the generation of spark discharge, but with such a high voltage pulse having a narrow pulse width, Increase the distance between electrodes, for example 5 cm
In the case above, it is difficult to form the corona streamer (accelerated electron flow) required for corona discharge treatment, and even if the corona streamer is formed, the effective corona discharge energy is small and The surface treatment effect on the surface is small.

Therefore, in order to sufficiently exert the effect of the corona discharge treatment on the surface of the resin molded product, it is necessary to take an extremely long treatment time or dispose the discharge electrode in the vicinity of the surface of the resin molded product. .. If the processing time is long, the productivity will be reduced, which is not suitable for industrial implementation. In addition, if the discharge electrode must be arranged near the surface of the resin molded product, the structure of the discharge electrode becomes complicated in the case where the resin molded product has a complicated three-dimensional shape, and the production of the electrode is troublesome. It is costly and expensive. If the discharge electrode is remade every time the shape of the resin molded product changes, it cannot be used for applications where the shape of the resin molded product is frequently changed. Further, when processing resin molded products having different shapes in one corona discharge treatment line, the electrodes have to be replaced every time the resin molded product changes, which is very troublesome work.

In order to solve this problem, the distance between the discharge electrode and the counter electrode may be increased to form a uniform discharge region between them, and a resin molded product may be passed between them for discharge treatment. .. However, in this case, the processed product (resin molded product)
If the conveyer used to convey the metal is formed of a conductive material, sparks may occur due to the high voltage generated between the discharge electrode and the discharge electrode, which is dangerous even if insulation is performed. In addition, it was thought that there was a problem with the uniformity of processing. Further, when the conveyor is made of a non-conductive material, it was considered that the uniformity of the treatment on the resin molded product could not be obtained.

Therefore, a method in which a resin molded product is placed on the counter electrode and the counter electrode itself is moved while keeping the distance between the discharge electrode and the discharge electrode constant can be considered. When carrying a large product such as a bumper, it is difficult to smoothly move the counter electrode, and the distance between the electrodes varies with the movement, and it is not always easy to obtain stable corona discharge. Also, when performing multi-product variable volume production with different shapes and dimensions, the size of the counter electrode must be determined according to the maximum size of the mounted product.
In the case of continuous production, the mounting pitch was large and the productivity was not good.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, to prevent the generation of harmful spark discharge, and to surely perform the treatment up to the edge of the resin molded product. At the same time, a corona discharge treatment device having a high surface treatment effect on a resin molded product, a uniform structure, a simple electrode structure, and a resin molded product having a different shape can be easily coped with. Especially.

[0014]

Among the corona discharge treatment apparatuses according to the present invention for solving the above-mentioned problems, the apparatus according to claim 1 is a discharge electrode and a counter electrode which are arranged to face each other, and a discharge electrode which faces the discharge electrode. Equipped with a high voltage generator that applies a high voltage between the electrodes to generate corona discharge, and place the resin molded product in the corona discharge treatment device that performs corona discharge treatment on the surface of the resin molded product having a three-dimensional shape. And a transfer conveyor that sequentially transfers in a fixed direction, a counter electrode disposed below the transfer conveyor along the transfer path of the resin molded product and facing the lower end shape of the resin molded product, and the surface of the counter electrode. And a plurality of discharge electrodes installed along the transfer path, facing the upper end shape of the resin molded product, above the transfer path of the resin molded product, and the high voltage generator,
A high voltage pulse with a pulse width of 1 μs or more, an applied electric field (peak value) / average electric field strength of 6 to 20 kv / cm, and a pulse frequency of 10 pps or more is applied between the discharge electrode and the counter electrode. It is a high voltage pulse generator.

The material of the resin molded product is made of any resin capable of improving the surface characteristics by corona discharge treatment, such as polypropylene, polyethylene and other polyolefin resins. Since the polyolefin resin does not have a polar group, it has a problem of poor adhesion and printability. Corona discharge treatment is effective for improving these characteristics. It goes without saying that the material of the resin molded product contains, in addition to the above-mentioned resin, various additives such as a rubber material, a pigment, a filler, an antioxidant, and an ultraviolet protective agent, if necessary.

As the shape of the resin molded product, one having an arbitrary three-dimensional shape such as an uneven portion, a rib or an opening is used according to the purpose of use of the resin molded product. This invention is
A good treatment effect can be exerted on a resin molded product in which an opening is formed in part. Specific examples of the resin molded product include an instrument panel pad (so-called instrument panel pad) for automobiles, a bumper, a molding, and the like.

As the transfer conveyor, an ordinary conveyor mechanism used in various transfer devices can be used if the above resin molded products can be placed and sequentially transferred in a fixed direction.
Specifically, a roller conveyor, a chain conveyor, a belt conveyor, etc. are mentioned. The specific shape and arrangement of the transfer conveyor are set according to the shape structure of the resin molded product. Since the transfer conveyor is arranged between the resin molded product and the counter electrode, it is preferable that the transfer conveyor has a relatively small thickness. In addition, the transfer conveyor is electrically insulated, and preferably, all the conveyor parts passing between the electrodes are made of an insulating material so that no discharge occurs between the transfer conveyor and the discharge electrode. must not.

The structure of the discharge electrode and the counter electrode may be basically the same as in the case of a corona discharge treatment device for a normal resin molded product, and a known electrode structure may be used. The counter electrode is arranged below the transfer conveyor along the laying path of the transfer conveyor, that is, the transfer path of the resin molded product. The counter electrode may have a shape roughly similar to the passage surface through which the lower end of the resin molded product passes when the resin molded product is transferred. As a material for the counter electrode, a conductive material used in a normal discharge device such as copper, aluminum, and stainless is used. Although the thickness of the counter electrode varies depending on its shape and size, it is usually preferably about 1.0 mm or more. Further, a thin foil or film made of a conductive material may be attached to the surface of the main body made of FRP or synthetic resin to form the counter electrode. Further, the counter electrode is not limited to a continuous plate or a planar shape, but may be a net or basket shape in which thin wires are arranged vertically and horizontally, or a plate in which a large number of holes or slits are formed.

The surface of the counter electrode is covered with a dielectric. Therefore, the transfer conveyor is installed on this dielectric. As the dielectric, a vinyl chloride resin, a Teflon resin, or another ordinary dielectric material is used. The thickness of the dielectric is 1 mm or more, preferably 5 to 20 mm. If the thickness of the dielectric is less than 1 mm, the desired effect of preventing spark discharge cannot be achieved sufficiently. Even if the thickness of the dielectric exceeds 20 mm, the effect of preventing spark discharge is not so different, and the drawbacks of increasing the bulk of the dielectric and increasing the cost become greater. The shape of the dielectric may be a curved surface or a flat surface that substantially conforms to the surface shape of the counter electrode. When a relatively thin dielectric layer is formed on the surface of the counter electrode, the counter electrode has a thickness of 1.0 mm or more, preferably 1.
If a plate material having a thickness of 6 mm or more is used, sufficient mechanical strength or durability can be provided. A thin foil or film of a conductive material such as copper or aluminum is formed on the back surface of the dielectric, and this conductive layer can be used as the counter electrode described above. In this case, in order to provide mechanical strength, it is preferable to form the dielectric material with a large thickness, and generally about 5 mm or more is preferable.

The discharge electrode is arranged above the transfer path of the resin molded product so as to face the upper end shape of the resin molded product, and a large number of discharge electrodes are installed at substantially constant intervals along the transfer path. That is, the lower end shape of each discharge electrode has a shape roughly similar to the passing surface through which the upper end of the resin molded product passes when the resin molded product is transferred, with a certain distance. There is. Specifically, for example, an electrode in which thin plate-shaped or knife-edge-shaped electrodes having an edge are arranged side by side at a position separated from the counter electrode by a certain distance is used. Further, the needle-shaped electrodes may be arranged in a brush shape or may be arranged in a staggered manner. The material of the discharge electrode is similar to that of the counter electrode.

The distance between the discharge electrode and the counter electrode, that is, the distance between the electrodes is set so as to satisfy the condition described later.
If the discharge electrode and the counter electrode are arranged in parallel with each other, the distance between the electrodes becomes the same at all positions, but the distance between the electrodes may be slightly different depending on the place. As the high-voltage pulse generator, basically the same high-voltage pulse generator as in the conventional corona discharge treatment method can be used. The high-voltage pulse generator can arbitrarily set the specific circuit structure as long as it can generate the high-voltage pulse as described above from a commercial AC power supply or a DC power supply. Various circuit structures or devices conventionally used as impulse high voltage generators can be used.

In the corona discharge treatment, the characteristics of the generated corona discharge or the treatment effect on the resin molded product changes depending on the waveform of the high voltage pulse applied between the discharge electrode and the counter electrode. In the device of the present invention, a device capable of producing a high voltage pulse as described below is used as the high voltage pulse generator. Among various elements of the high voltage waveform pulse, first, the pulse width can be set to 1 μs or more, preferably 2 to 20 μs. Under general processing conditions, 3 to 10 μs is preferable. Pulse width is 1μ
When it is less than s, when the distance between the electrodes is increased, the surface treatment effect on the resin molded product is weak and the energy efficiency becomes extremely low. When the pulse width is too large, harmful spark discharge (spark) is likely to occur, which is not preferable.

Next, the average electric field strength expressed by applied voltage (peak value) / distance between poles is 6 to 20 kv / cm, preferably 7
Be prepared to be able to set to 10 kv / cm. When the average electric field strength is less than 6 kv / cm 2, the effect of corona discharge treatment becomes weak and the required treatment time becomes long. Average electric field strength is 20kv
If it exceeds / cm 3, harmful spark discharge (spark) is likely to occur, which is not preferable.

The applied voltage is defined by the peak value of the voltage that is actually applied between the discharge electrode and the counter electrode that perform corona discharge treatment on the resin molded product. To specifically measure the applied voltage, the peak value of the high-voltage pulse waveform flowing between the discharge electrode and the counter electrode may be measured. The preferred range of applied voltage depends on the value of the distance between the electrodes, and for example,
When the distance between the electrodes is 30 cm, the applied voltage is 180-30
The range is set to 0 kv, more preferably 200 to 240 kv.

The inter-electrode distance is defined by the distance between the discharge electrode and the counter electrode. The actual distance between the electrodes may be determined by the maximum dimension of the resin molded product to be subjected to corona discharge treatment. In the present invention, the distance between the electrodes can be set to 5 cm or more. In practice, for example, when the resin molded product is a bumper, the distance between the electrodes is 25 cm.
It is preferably set in the range of ~ 35 cm. Next, the pulse frequency is set to be 10 pps or more. Under normal processing conditions, it is set to 50 to 100 pps. If the pulse frequency is less than 10 pps, the energy of effective corona discharge treatment per unit time is small and the time required for surface treatment is long, which is not preferable. Pulse frequency is 200
When it exceeds pps, it becomes technically difficult to generate such a high-voltage pulse having a high pulse frequency with the above-mentioned pulse width and average electric field strength. Pulse frequency is 30
If the range is set to exceed 0 pps, the high voltage generator becomes very large, the equipment cost becomes excessive, and it becomes unprofitable industrially, which is not preferable.

In order to create the above-mentioned pulse waveform in the high-voltage pulse generator, it is necessary to appropriately select the structure and characteristics of the high-speed switch mechanism, the circuit elements such as resistors and capacitors in the pulse shaping circuit. However, the design of such a circuit can be performed by combining the techniques of high voltage pulse generators in various ordinary fields.

Next, in the corona discharge treatment apparatus of the present invention, the apparatus described in claim 2 applies a high voltage between the discharge electrode and the counter electrode, which are arranged to face each other. In a corona discharge treatment device that is equipped with a high-voltage generator that generates a corona discharge by applying a voltage, and performs corona discharge treatment on the surface of a resin molded product having a three-dimensional shape, columns are mounted on a large number of supports that run in a certain direction. It is erected, and a mounting member for the resin molded product is attached to the upper end of the column, and along the transfer path of the resin molded product, below the mounting member, facing the lower end shape of the resin molded product. The counter electrode is installed, the counter electrode is provided with a passage groove through which the support column passes along the traveling path of the support base, and the surface of the counter electrode is covered with a dielectric material. To the top shape of the resin molded product A large number of discharge electrodes are installed at regular intervals along the transfer path, and the high voltage generator has a pulse width of 1 μs or more between the discharge electrode and the counter electrode, and the applied voltage / distance between electrodes. The average electric field strength represented by
It is a high voltage pulse generator that applies a high voltage pulse of 10 kv / cm 2 and a pulse frequency of 10 pps or more.

The basic structure of the device is the same as the device of claim 1, and what has been described for claim 1 is applied as it is. In the apparatus according to the second aspect, the support base is used as the transfer means of the resin molded product. The support base is driven by an ordinary conveyor mechanism or the like, and a large number of support bases are arranged in a straight line and travel in a fixed direction. A column is erected on each support. The pillar is exposed above the counter electrode through a passage groove formed through the counter electrode. A mounting member is attached to the upper ends of the columns. One or a plurality of resin molded products are mounted on the mounting member, and the resin molded products are transferred in a fixed direction as the support base travels.

The structure of the mounting member is determined according to the shape of the resin molded product to be mounted thereon. In order to stably mount the resin molded product, it is preferable that the mounting member has a structure that extends in the horizontal direction. As the mounting member, a plate-shaped member, a frame-shaped member formed by combining thin rods, a net-shaped member, or the like is used. The pillars are preferably as thin as possible so long as they can reliably support the mounting member and the resin molded product. This is because the width of the passage groove formed in the counter electrode is determined by the thickness of the pillar.

It is also possible to attach a plurality of columns or mounting members to one support base. It is preferable that either or both of the support column and the mounting member are made of an insulating material. Since the counter electrode passes through the position where the support pillar of the support as the transfer means penetrates the counter electrode, the counter electrode is provided with a passage groove along the path of the support pillar, except that the counter electrode has a passage groove. The device has the same structure as the device of Item 1, and the surface of the counter electrode is covered with a dielectric.
It is preferable that the dielectric covers the inner edge portion of the passage groove. If the passage groove becomes wide, the function of the counter electrode is affected, so the passage groove should be narrow. Specifically, it is preferable that the width of the passage groove is set to about 1/3 or less of the distance between the electrodes.

The structure such as the discharge electrode and the high voltage pulse generator may be the same as that of the device of claim 1 described above. According to a third aspect of the present invention, in the apparatus according to the second aspect, the support column erected on the support base is configured to swing in the direction along the passage groove with the attachment portion to the support base as a fulcrum. In order to swing the column, a normal swing mechanism used in various mechanical devices such as a cam mechanism, a guide roller mechanism, a cylinder mechanism, and a gear mechanism is used. The swing of the pillar is
It suffices that the resin molded product mounted on the mounting member is subjected to corona discharge treatment while changing the inclination or the posture of the discharge electrode within a certain range.

[0032]

In the conventional corona discharge treatment apparatus using a high-voltage pulse, sufficient corona discharge treatment cannot be performed unless the discharge electrode and the counter electrode are in close contact with or close to the resin molded product. Conventionally, it is considered that unless a high-voltage pulse having a pulse width of less than 1 μs and an extremely narrow pulse width is used as the high-voltage pulse, spark discharge occurs and good corona discharge treatment cannot be performed. When a high voltage pulse with such a narrow pulse width was used, it was thought that if the electrodes were separated from the resin molded product, corona discharge would become extremely difficult to occur, and sufficient corona discharge treatment could not be performed. ..

On the other hand, as a result of a detailed examination of the waveform of the high voltage pulse, the present inventors found that the pulse width was 1 μm.
If a high-voltage pulse with an electric field strength of 6 to 20 kv / cm or more and a pulse frequency of 10 pps or more is used, and a dielectric is interposed between the counter electrode and the resin molded product, harmful spark discharge will occur. It was found that even if a relatively wide space is provided between the resin molded product and the discharge electrode and the counter electrode, a good corona discharge treatment can be performed on the surface of the resin molded product. In addition, by covering the surface of the counter electrode with a dielectric, even if the conveyor on which the resin molded product is placed is made of a dielectric, the uniformity of processing is not lost. Furthermore, even if a part of the counter electrode is lacking, for example, a perforated state where a continuous groove or the like is formed in the central portion, if the perforated portion is within a certain range, the treatment We also found that the uniformity was not lost. As a result, even in the case of a resin molded product having a complicated shape, a relatively simple electrode shape can be adopted, and it is not necessary to change the shape of each electrode for each resin molded product.

Therefore, while sequentially transferring a large number of resin molded products in a fixed direction, a discharge electrode and a counter electrode covered with a dielectric are arranged above and below the transfer path of the resin molded products,
By applying a high voltage pulse generated by a high voltage pulse generator between the electrodes and satisfying the above conditions, continuous corona discharge treatment for many resin molded products becomes possible,
The processing efficiency can be improved.

If there is a space between the resin molded product and the discharge electrode or the counter electrode, the resin molded product may collide with the electrode even if the resin molded product swings up and down or shifts in position during transfer. Without any trouble, smooth transfer can be performed, and the finish of the surface treatment is uniform and stable. As long as the resin molded product has a shape capable of transferring the space between the discharge electrode and the counter electrode, the corona discharge treatment can be continuously performed on the resin molded products having different shapes with the same electrode structure.

Further, in the invention of claim 1, since the counter electrode covered with the dielectric is provided below the transfer conveyer for transferring the resin molded product, and the discharge electrode is provided above the resin molded product, the resin The molded products can be easily transferred and the structure of the transfer conveyor can be simplified. Even if there is a transfer conveyor between the counter electrode and the resin molded product, and there is a gap between the counter electrode and the resin molded product, using the high-voltage pulse waveform as described above will result in a sufficiently good corona. Discharge processing can be performed.

According to the second aspect of the present invention, only the mounting member of the transfer means exists between the resin molded product and the counter electrode, and the support base, which is the main body of the transfer means, and its driving means. Since it suffices to install such as below the counter electrode, the effect of corona discharge treatment can be enhanced by bringing the resin molded product and the counter electrode relatively close to each other. In order to install the transfer conveyor on the counter electrode, it is necessary to use a transfer conveyor made of resin or the like having excellent insulating properties and light weight, and it is difficult to transfer a large and heavy resin molded product. However, when the transfer means is installed below the counter electrode as in the present invention, it is possible to use the transfer means having sufficient mechanical strength or transfer ability, and even for a heavy resin molded product. Can be applied.

According to the third aspect of the invention, when the support column swings,
The resin molded product also swings, and the resin molded product is subjected to corona discharge treatment while changing the angle or the posture within a certain range with respect to the discharge electrode. If corona discharge treatment is performed with the discharge electrode and resin molded product in the same posture, corona discharge may not reach enough depending on the shape of the resin molded product, and the effect of corona discharge treatment may be localized. There may be weak points. Therefore, as described above, if the resin molded product swings to change its posture, the corona discharge treatment can be uniformly applied to every corner of the resin molded product.

[0039]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an external structure of a corona discharge treatment device according to the present invention. As the resin molded product 10, a bumper for automobiles, which is made of polypropylene resin and has a substantially U-shape, is used. Corona discharge treatment is applied as a pretreatment for coating the surface of the resin molded product 10. A large number of resin molded products 10 are sent side by side on a roller conveyor 70 laid in the shape of two rails. The roller conveyor 70 is installed on the counter electrode 20 and is made of an insulating resin or the like. The counter electrode 20 is made of a plate material having a U-shaped cross section along the lower end shape of the resin molded product 10, and the upper surface of the counter electrode 20 is covered with a dielectric 60.

Discharge electrodes 40 in the shape of a thin strip bent in a U shape are arranged at regular intervals above the traveling path of the resin molded product 10. The plate thickness of the discharge electrode 40 is 0.1 to 0.
It is preferable to use one having a width of about 2 mm and a plate width of about 10 to 50 mm. The shape of the lower end edge of the discharge electrode 40 is the resin molded product 1.
It roughly corresponds to the top edge shape of 0,
The lower end edge of the discharge electrode 40 and the surface of the counter electrode 20 are arranged substantially parallel to each other and are spaced apart by about several tens of cm. In addition,
The radius of curvature of the lower edge of the discharge electrode 40 or the upper surface of the counter electrode 20 is set to 50 mm or more, preferably 100 mm or more. This is because if the radius of curvature is small, the generation state of corona discharge changes between the portion having a small radius of curvature and other portions, and it is difficult to perform uniform corona discharge treatment. The upper part of the discharge electrode 40 is supported by a strip-shaped connecting fitting 42 and is electrically connected integrally. Discharge electrode 40
Is detachably attached to the connection fitting 42 with a bolt or the like, and the attachment pitch of the discharge electrode 40 can be changed as necessary. Both ends of the connection fitting 42 are attached to the frame 44. Also, the connection fitting 42
A high voltage pulse generator 500 is connected to the high voltage pulse generator 500 via a high voltage cable or the like.

Therefore, on the counter electrode 20, the resin molded product 10 mounted on the roller conveyor 70 is transferred under the discharge electrode 40, and a high voltage pulse is applied between the discharge electrode 40 and the counter electrode 20. Corona discharge can be applied to generate corona discharge, and the surface of the resin molded product 10 can be subjected to corona discharge treatment. FIG. 2 shows a circuit structure of the corona discharge treatment device. The resin molded product 10 is mounted on the counter electrode 20 via the dielectric 60, and the discharge electrode 40 is arranged above the resin molded product 10. The distance W between the discharge electrode 40 and the counter electrode 20 is the inter-electrode distance. A waveform shaping circuit 52 and a negative high voltage power supply 50 are provided in a circuit connected to the discharge electrode 40 and the counter electrode 20. The negative-polarity high-voltage power supply 50 is capable of generating a desired high-voltage current from a low-voltage DC power supply, similarly to various ordinary high-voltage devices.
The waveform shaping circuit 52 is provided with a fixed gap switch 53 for pulse generation, an inductance L, a charging / discharging capacitor C, and a load resistance R ₁ . The fixed gap switch 53 is a so-called ball gap switch. By appropriately setting the conditions such as the circuit constant of the waveform shaping circuit 52, a high voltage pulse exhibiting desired characteristics is applied between the discharge electrode 40 and the counter electrode 20.

FIG. 3 shows the waveform of the high voltage pulse. This waveform is a waveform obtained when the waveform of the voltage applied between the discharge electrode 40 and the counter electrode 20 is measured by an oscillograph. The waveform P ₀ is a waveform of a high voltage pulse having a pulse width of 1 μs or less, which has been conventionally used, and has a pulse width t of 0.2 μs and a peak value Vp of about 50 kv.

On the other hand, the waveform P ₁ is a waveform showing an example of the high voltage pulse used in the present invention. This waveform is
A so-called damped oscillation waveform is shown. In such a damped oscillation waveform, the pulse width t is defined by the pulse width of the first wave, specifically, t = 4 μs. Crest value Vp
Is also defined by the first wave and shows 200 kv. Thus, in this embodiment, as compared with the conventional waveform P _0, wide much pulse width t, so that using a large waveform P ₁ peak value Vp. Then, as shown in FIG. 4, such a waveform P ₁ is repeatedly generated at regular intervals. In this embodiment, one pulse is generated about every 4/60 seconds, and the pulse frequency is 15 pps.

In the high voltage pulse generator of FIG. 2, the decay time of the high voltage pulse can be adjusted by the load resistance R ₁ in the circuit, and the larger the load resistance R _{1, the} longer the decay time. The pulse width t is set by the value of the inductance L. The charging / discharging capacitor C varies depending on the total length of the discharge electrodes, but is usually set to a value about 10 times the capacitance of the processing discharge region.

Further, it is preferable to use a protective resistor R ₂ having an appropriate value according to the value of the charging / discharging capacitor C.
The pulse frequency is determined by the value of the protective resistance R ₂ and other conditions, and as a result, the length of processing time required to perform the predetermined corona discharge treatment on the resin molded product 10 changes. Specifically, for example, if the protection resistor R ₂ is increased when the capacitance C of the capacitor is constant, the pulse frequency decreases,
The pulse frequency increases as the protective resistance R ₂ decreases. Under normal processing conditions, pulse frequency is 20-100pp
If s, the processing time is about 1 to 6 minutes.
The fixed gap switch 53 is usually a spherical one, but a snow dharma type with a small protrusion at the tip can exhibit good performance. If compressed air whose temperature and humidity are adjusted and controlled is supplied to the space around the fixed gap 53, better and stable performance can be exhibited.
In the pulse shaping circuit 52 of FIG. 2, a resonance phenomenon occurs and a discharge voltage higher than the input voltage can be obtained, which is preferable in terms of both safety and economy.

Before the corona discharge treatment is applied to the resin molded product 10, various pretreatments can be performed in the same manner as the conventional method. For example, in order to keep the surface of the resin molded product 10 clean, it is preferable to carry out solvent cleaning, acid cleaning, and alkali cleaning, which are then washed with water and dried, and then subjected to corona discharge treatment. However, the above-described cleaning process is performed in the resin molded product 1
When 0 is molded by injection molding or during storage after molding, corona discharge treatment can be performed as it is without undergoing a cleaning step if it is not contaminated with oil or dust. it can.

Explaining a specific example of the cleaning step, the following steps can be sequentially performed. First, 50-6
Perform alkali cleaning with a shower spray at 0 ° C. for 0.5 to 1 minute. Then, hot water washing with a shower spray is performed at 40 to 50 ° C. for 0.5 minutes. Next, neutralization adjustment is performed at 40 to 50 ° C. for 0.5 minutes. Again, at 40-50 ° C.
After washing with hot water for 5 minutes, it is dried at 90 to 100 ° C. for 4 to 5 minutes, and the corona discharge treatment as described above is performed. The corona discharge treatment may be performed, for example, at 20 to 30 ° C. for about 3 to 6 minutes. After performing the corona discharge treatment, it is brought into a normal painting process.

In the above-mentioned embodiment, the dielectric 60 covers the counter electrode 20 without any gap, but it is possible to leave a gap in the dielectric 60 at an intermediate position between the adjacent discharge electrodes 40. In this way, when the dielectric 60 is provided with a partial gap, corona discharge from the discharge electrode 40 to the counter electrode 20 is favorably generated, and the corona discharge treatment effect on the resin molded product 10 is enhanced. However, the gap of the dielectric 60 needs to be provided in a position and shape in which spark discharge is unlikely to occur. That is, the position close to the discharge electrode 40 is not preferable, and it is not preferable that the area of the gap is too large.
The size of the gap is sufficiently effective even if it is narrow enough to form a linear cut in the dielectric 60.

Next, FIG. 5 shows another embodiment. In this embodiment, the rail 8 is provided below the counter electrode 20.
A large number of support bases 80 that travel on 6 are installed. Vertical columns 82 are erected on the support 80. A passage groove 22 is formed in the center of the counter electrode 20 along the passage of the pillar 82. At the upper end of the pillar 82,
A mounting member 84 having a substantially H-shape formed by combining thin rods is attached. The mounting member 84 is disposed along the surface of the dielectric 60 on the upper surface of the counter electrode 20,
The lower surface of the resin molded product 10 can be supported.
Therefore, as the support base 80 travels, the mounting member 84
The resin molded product 10 placed on the substrate is sequentially transferred in a fixed direction. Mounting member 84, support column 82, and support base 8
0 is insulated from the floor surface or the counter electrode 20.

FIGS. 6 and 7 show an embodiment in which a swinging mechanism is added to the column 82 of the support 80 in the embodiment of FIG. The column 82 is mounted on the support base 80 at a fulcrum fulcrum 800 so as to be rotatable along the direction of the passage groove 22. A weight, that is, a balancer 801 is attached to the lower end of the column 82 below the fulcrum 800. Due to the gravity applied to the balancer 801, a force is always applied to return the balancer 801 to the lowest position, that is, to the state in which the column 82 stands vertically. In the middle of the column 82, guide arms 802 protruding left and right are attached at two upper and lower positions. A sliding roller 804 is attached to the tip of the guide arm 802. Sliding roller 8 arranged below the column 82
04, a swing guide rail 810 abuts the lower surface of the sliding roller 804. The swing guide rail 810 is installed along the entire traveling path of the support base 80. The rocking guide rail 810 has a cylinder mechanism 812 that operates vertically in the lower surface thereof, and the rocking guide rail 810 moves up and down as the cylinder mechanism 812 expands and contracts.

A similar rocking guide rail 820 is also in contact with the sliding roller 804 arranged above the column 82. A cylinder mechanism 822 is attached to the upper surface of the swing guide rail 820. Therefore,
The upper and lower swing rollers 804 of the column 82 are sandwiched by the outer swing guide rails 810 and 820. In this state, the upper and lower swing guide rails 810, 8
When 20 is raised or lowered, the swing guide rail 8
The oscillating roller 804 is pushed up or down by 10, 820.

When the oscillating roller 804 is pushed down or pushed up, the column 82 which is rotatably attached at the fulcrum 800 is tilted back and forth from the vertical state. The slanted column 82 is formed by the balancer 801.
Will automatically return to the vertical state. That is, the column 82 swings back and forth by repeating the periodic raising and lowering operations of the swinging guide rails 810 and 820.
The swing angle of the support column 82 is determined by the swing guide rails 810, 8
It can be adjusted by the amount of elevation of 20. Normally, the swing range may be set to about 15 ° in each of the front and rear.

In the apparatus provided with such a swinging mechanism of the column 82, the resin molded product 10 mounted on the mounting member 84 is
A predetermined corona discharge treatment is performed while swinging back and forth and periodically changing the inclination or posture with respect to the discharge electrode 40. Therefore, even if a part of the resin molded product 10 has a dent or a shadow that is difficult to perform corona discharge treatment, such a dent or a shadow may also be formed if the posture of the resin molded product 10 changes. The discharge treatment can be performed well. As a result, uniform and good corona discharge treatment can be performed on the entire resin molded product 10.

FIG. 8 shows an embodiment having a different electrode structure. The discharge electrode 40 is the same as in each of the above-described embodiments, but the counter electrode 20 is configured by combining thin wire rods in a cage shape, and the overall schematic shape is the same as that in the above-described embodiment. Further, in this embodiment, the counter electrode 20
Is divided into left and right parts, and a gap G serving as the passage groove 22 is formed in the center of the upper surface. As in this embodiment, the counter electrode 2
Even if 0 has a partial space, good corona discharge can be generated between the discharge electrode 40 and the discharge electrode 40 by appropriately setting the gap spacing and density.
Specifically, when the distance between the electrodes is 30 cm, no problem occurs in the function of the corona discharge treatment even if the central gap G of the counter electrode 20 is about 100 mm.

When the discharge electrode 40 or the counter electrode 20 has a divided structure, the shape of the resin molded product 10
The distance between the electrodes can be finely adjusted by changing the arrangement of the divided electrodes. Next, a corona discharge treatment was performed using the corona discharge treatment device of the present invention,
A more specific example will be described.

Example 1 Using the apparatus having the structure shown in FIG. 1, a conveyor 70 made of only a dielectric material was used to subject a polypropylene bumper as a resin molded product 10 to corona discharge treatment. The processing conditions were as follows. Distance between poles is 30 cm. The pulse width was 4 μs, the pulse frequency was 100 pps, the processing time was 5 minutes, and the dielectric thickness was 1.0 mm (PVC sheet).

The bumper 10 that had been subjected to corona discharge treatment was painted. As a paint, NBC R-271 (2
Liquid-curable urethane paint) was used for coating by a conventional method and dried. Drying was performed at 90 ° C. for 30 minutes. After leaving it for 24 hours, a 180 ° peeling test was performed to measure the peel strength of the paint, and the effect of corona discharge treatment was confirmed. The measurement points are point A in FIG. 1 (a rear position directly above the center with the bumper placed on the conveyor), point B (also,
Forward position in the center directly above), C ₁ -C ₃ (position separated outwardly in order from the point A), it is set to a position) apart outwardly in order from D ₁ to D ₃ (point A. Table 1 shows the measurement results.

[0058]

[Table 1] ────────────────────────────────── Crest value Average electric field strength Peel strength kv kv / cm g / cm ────────────────────────────────── Measurement position A B C ₁ -C ₃ D ₁ -D ₃ ────────────────────────────────── Example 1.1 120 4.0 0 0 0 0 0 Example 1.2 180 6 0.0 1200 1100 1300-1400 1200-1300 Example 1.3 240 240 1900 1900 1900-2000 1900-2000 ───────────────────────── --Example 2 --Example 2 Example 2 was carried out under the same conditions as Example 1 except that the dielectric thickness was 5 mm. Table 2 shows the measurement results.

[0059]

[Table 2] ────────────────────────────────── Crest value Average electric field strength Peel strength kv kv / cm g / cm ────────────────────────────────── Measurement position A B C ₁ -C ₃ D ₁ -D ₃ ────────────────────────────────── Example 2.1 120 120 4.0 0 0 0 0 Example 2.2 180 6 0.0 1100 1000 1200-1350 1100-1350 Example 2.3 240 240 1900 1800 1850-2000 1800-2000 ────────────────────────── ────────── Example 3 In Example 1, the dielectric thickness is 10 mm and 20 mm.
The same conditions as in Example 1 except that the above were used. As a result, almost the same results as in Example 2 were obtained.

-Comparative Example 1-Example 1 except that no dielectric is used.
It carried out on the same conditions as. Table 3 shows the measurement results.

[0061]

[Table 3] ────────────────────────────────── Crest value Average electric field strength Peel strength kv kv / cm g / cm ────────────────────────────────── Measurement position A B C ₁ -C ₃ D ₁ -D ₃ ────────────────────────────────── Example 2.1 120 120 4.0 0 0 0 0 Example 2.2 180 6 0.0 1200 1000 1900-2000 1700-2000 Example 2.3 240 240 Spark generation ──────────────────────────────── ─── According to the results of Examples 1 to 3 and Comparative Example 1 above, if the thickness of the dielectric is 1 mm or more, even if the carrier device installed on the counter electrode is made of the dielectric, it is uniform. It can be seen that various corona discharge treatment effects can be obtained.

-Example 4-Using the apparatus having the structure shown in FIG. 5, the same operation as in Examples 1-3 was carried out. As a result, at the position of the passage groove 22 formed in the counter electrode 20, that is, at the points A and B of the measurement position, the peel strength was slightly reduced as compared with the other portions, but this is a practical problem. I confirmed that it is not. In this apparatus, since the resin molded product is placed on the support 80 and conveyed, corona discharge treatment can be efficiently performed even for a resin molded product having a considerable weight.

-Comparative Example 2-Using the comparative apparatus shown in FIG. 9, the same procedure as in Examples 1 to 3 was carried out. The device shown in FIG. 9 is
The counter electrode 200 having a structure divided for each support 80.
When the support base 80 moves, the corona discharge treatment is performed while the counter electrode 200 and the resin molded product 10 placed thereon move sequentially below the discharge electrode 40.

As a result, the corona discharge treatment effect of the entire bumper was almost the same as that of Example 4, but instability was observed in the discharge condition. Also, variations were observed in the peel strength measurement results. This is the counter electrode 20
It is considered that this occurred because the distance between the electrodes and the discharge electrode 40 slightly fluctuated with the movement of 0. Therefore,
As in the embodiment of the present invention, the device in which the resin molded product 10 is moved while the counter electrode 20 and the discharge electrode 40 are fixed is excellent in the uniformity of the corona discharge treatment. It was proven.

[0065]

As described above, according to the corona discharge treatment apparatus of the present invention, it is possible to perform corona discharge treatment using a high voltage pulse while transferring a resin molded product,
It is possible to improve the efficiency of the corona discharge treatment and improve the treatment performance. In particular, by using the above-mentioned specific high voltage pulse waveform, and fixing the discharge electrode and the counter electrode and covering the counter electrode with a dielectric, stable corona discharge can be achieved without causing harmful spark discharge. The formed corona discharge product can be subjected to favorable corona discharge treatment on the surface thereof.

Even if the discharge electrode and the counter electrode and the resin molded product are separated from each other, good corona discharge treatment is possible. The corona discharge treatment can be performed while continuously transferring with a transfer conveyor. Moreover, even if the shape of the resin molded product is changed, it is not necessary to recreate the electrodes. Therefore, the time and effort required for electrode production can be greatly reduced, and the work efficiency of the entire corona discharge treatment can be improved.
The work cost can also be reduced. In addition, one corona discharge processing line can be used to continuously process resin molded products of different shapes without replacing the electrodes one by one, making it suitable for production sites of various products that require large-scale processing. If applied, it can greatly contribute to improvement of workability of corona discharge treatment or reduction of work cost.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a corona discharge treatment apparatus showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a circuit configuration of a high voltage pulse generator.

FIG. 3 is a diagram showing the waveform of one pulse of a high voltage pulse.

FIG. 4 is a diagram showing a high voltage pulse generation state over time.

FIG. 5 is a perspective view of the entire apparatus showing another embodiment.

FIG. 6 is a side structure view showing a swing mechanism of a column.

FIG. 7 is a sectional view taken in a direction orthogonal to the previous figure.

FIG. 8 is a perspective view showing an embodiment having a different electrode arrangement.

FIG. 9 is an overall perspective view of a corona discharge treatment device as a comparative example.

[Explanation of symbols]

 10 Resin Molded Product 20 Counter Electrode 40 Discharge Electrode 60 Dielectric 70 Roller Conveyor 500 High Voltage Pulse Generator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Tanaka No. 3 Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Masatoshi Fujii No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Corporation (72) Inventor Akitsu Akue 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd. (72) Inventor Koji Ueki 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd. (72 ) Inventor Ikuo Tochizawa 19-17 Ikedanaka-cho, Neyagawa City, Osaka Prefecture Japan Paint Co., Ltd.

Claims (3)

[Claims] 1. A resin having a three-dimensional shape, comprising a discharge electrode and a counter electrode arranged to face each other, and a high voltage generator for generating a corona discharge by applying a high voltage between the discharge electrode and the counter electrode. In a corona discharge treatment device that performs corona discharge treatment on the surface of a molded product, a transfer conveyor that places the resin molded product and sequentially transfers it in a certain direction, and along the transfer path of the resin molded product, below the transfer conveyor. , A counter electrode arranged so as to face the lower end shape of the resin molded product, a dielectric covering the surface of the counter electrode, and above the transfer route of the resin molded product,
The high voltage generator is provided with a large number of discharge electrodes arranged along the transfer path so as to face the upper end shape of the resin molded product, and the high voltage generator applies a pulse width of 1 μs or more between the discharge electrodes and the counter electrodes. Corona discharge treatment characterized by being a high-voltage pulse generator that applies a high-voltage pulse having an average electric field strength represented by voltage (peak value) / distance between electrodes of 6 to 20 kv / cm and a pulse frequency of 10 pps or more. apparatus. 2. A resin having a three-dimensional shape, comprising a discharge electrode and a counter electrode arranged to face each other, and a high voltage generator for generating a corona discharge by applying a high voltage between the discharge electrode and the counter electrode. In a corona discharge treatment device that performs corona discharge treatment on the surface of a molded product, columns are erected on a large number of supports that run in a fixed direction, and a mounting member for resin molded products is attached to the upper ends of the columns. Along the transfer path of the resin molded product, a counter electrode is installed below the mounting member so as to face the lower end shape of the resin molded product, and the counter electrode is provided with a column along the traveling path of the support base. A passage groove is formed to pass through, and the surface of the counter electrode is covered with a dielectric. Above the transfer path of the resin molded product, a plurality of grooves are formed along the transfer path so as to face the upper end shape of the resin molded product. High-voltage generator equipped with discharge electrodes However, a high voltage pulse with a pulse width of 1 μs or more, an average electric field strength represented by the applied voltage / distance between electrodes of 6 to 20 kv / cm, and a pulse frequency of 10 pps or more is applied between the discharge electrode and the counter electrode. A corona discharge treatment device characterized by being a voltage pulse generator. 3. The corona discharge treatment according to claim 2, wherein the support column erected on the support base swings in a direction along the passage groove with the mounting portion to the support base as a fulcrum. apparatus.