JPH0612682B2 - Method of manufacturing counter electrode for corona discharge treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a method for producing a counter electrode used for corona discharge treatment of a resin molded product.

(Prior Art) Since polyolefin resins such as polypropylene have few polar groups, they have the property that paints, adhesives, printing, etc. do not easily adhere to their surfaces. Therefore, paint on the surface of the resin,
In the case of performing adhesion, printing, etc., it is necessary to improve the adhesion by performing a surface modification treatment as a pretreatment.

Flame treatment (flame treatment) and acid solution treatment using a dichromic acid solution, etc. have been conventionally performed as a modification treatment for a three-dimensional resin molded product made of this polyolefin resin, but recently plasma treatment has also been performed. It came to be done. Since the plasma treatment can activate almost the entire surface of the resin molded product at once,
It has achieved great results in painting and pre-bonding treatment for moldings.

(Problems to be Solved by the Invention) However, since a reduced pressure plasma gas atmosphere is required in the plasma processing, large-scale and expensive equipment such as a vacuum chamber, a vacuum pump, a valve device, and a carrier gas is required. However, there is a problem that it takes time to reduce the pressure inside the vacuum chamber. In addition, since the process is inevitably batch-processed, it is difficult to automate the process, and there is also a problem that the vacuum is broken in each process and it takes time to reduce the pressure next time.

Therefore, the present inventor has focused on corona discharge treatment performed as a modification treatment of a resin film, but many difficulties are involved in adopting this treatment method for the modification treatment of a three-dimensional resin molded product. One of them is that, when the molded product has various three-dimensional shapes, in the conventional roll-shaped or flat-shaped counter electrode, a large air layer is generated between the resin and the discharge electrode, and The problem is that the corona discharge does not occur because the distance between the two becomes large.

Therefore, it has been considered to form the counter electrode into a shape substantially the same as the shape of the back surface of the three-dimensional resin molded product. In this case, a resin mold having the same shape as the back surface of the three-dimensional resin molded product is used. Since it has to be formed and coated with a thin film conductive layer on its surface to form a counter electrode, a plurality of manufacturing steps are required and the work is very troublesome.

Configuration of the Invention (Means for Solving Problems) In order to solve the above problems, the present invention melts a material containing a conductive substance in a non-conductive substance, and uses the molten material as an inner surface of a molded article. A means of forming a counter electrode by pouring into and curing the same is adopted.

(Operation) That is, since the counter electrode is formed of a material containing a non-conductive substance containing a conductive substance, the conductive substance in the non-conductive substance forms an electrical chain contact structure, The whole works like a conductor.

The counter electrode is formed in the same shape as the inner surface of the molded product to be subjected to corona discharge treatment.

(Embodiment) An embodiment embodying the present invention will be described below with reference to the drawings.

First, a molded product to be subjected to corona discharge treatment in this example will be briefly described. This molded product is a three-dimensional resin molded product having three-dimensional unevenness. In addition, the resin mentioned here particularly refers to a synthetic resin that is a dielectric.

A three-dimensional resin molded product subjected to corona discharge treatment according to the present embodiment, as shown in FIGS. 1 to 3, is a vehicle instrument panel pad (hereinafter abbreviated as instrument panel pad) formed of a PP resin as a dielectric. ) 1 and a skin sheet made of PVC (polyvinyl chloride) resin is mounted on the surface thereof to form an instrument panel.

The instrument panel pad 1 has a boundary between an upper surface 2 and a front surface 3,
A convex corner portion 5 is provided at a boundary between the upper surface 2 and the side surface 4, or the like.

Further, two shallow plate portions 6 and 7 are provided on both left and right sides of the upper surface 2 of the instrument panel pad. Therefore, as shown in FIG. 2, concave corner portions 9 are present at the bottom edges of the tray portions 6 and 7, respectively. An air outlet 10 for side defroster air is provided at the left end of the upper surface 2, and 2 are provided on both the left and right sides of the front surface 3.
Air vents 11 and 12 for ventilation and air conditioning are formed respectively. The square outlets 10, 11 and 12 have a substantially rectangular shape, and rounded corner portions 13 are formed at edges and four corners.

As described above, the instrument panel pad 1 is a three-dimensional resin molded product and is characterized in that it has many corners 5, 8, 9, 13.

Now, an apparatus for performing corona discharge treatment on the instrument panel pad 1 will be described.

This corona discharge treatment device is placed on a base 80 formed in two steps in front and back by a metal frame. When the present device is divided, A: the instrument panel pad 1 is fixed, and the counter electrode is brought into contact with the back surface thereof. To this end, the counter electrode means A grounded at the first stage of the base 80 and B: corona discharge treatment and moving means for three-dimensionally moving the same are provided. Discharge electrode means B arranged in the second stage; C: high frequency applying means C arranged on the shelf 14 on the left side of the base 80 to apply a high frequency between the electrodes; D: electrode moving means B Control unit D, which is grounded on the right side of the base 80 in order to control the.

Hereinafter, the details of each of the units A to D will be sequentially described.

[Counter electrode means A]

As shown in FIGS. 1, 2, 4, and 5, a hollow electrode base 61 is installed on the first stage of the base 80.
A counter electrode 62 formed so as to match the three-dimensional shape inside the instrument panel pad 1 is provided on the upper part of
The instrument panel pad 1 is adapted to be supported from the inside.

The counter electrode 62 includes a non-conductive epoxy resin powder 62a and a conductive carbon black powder 62a.
It is formed by melting a material containing b and pouring it into the inner surface of the instrument panel pad 1 to cause reaction curing. Therefore, inside the counter electrode 62, the carbon black powders 62b are close to each other at a close distance to form an electrical chain contact structure. That is, the electrical chain contact structure of the carbon black powders 62b serves as a conventional conductive layer.

Therefore, in the counter electrode 62, the carbon black powder 62b contained therein functions as a conventional conductive layer,
The counter electrode 62 itself can be easily formed in the same shape as the three-dimensional shape of the back surface of the instrument panel pad 1.

As described above, the counter electrode 62 of the present embodiment does not need to have a two-layer structure of a resin mold having the same shape as the inner surface of a three-dimensional resin molded article as in the conventional case and a conductive layer coated on the surface thereof. It can be formed very easily and inexpensively, and is effective in reducing equipment costs and improving reproducibility.

The carbon black powder 62b has an average particle diameter of 10 to 100 mμ, and in the present embodiment, acetylene carbon black flake powder having the best conductivity and easy surface contact is used. Spherical powders, branch powders, needle powders, fibrous powders that are used as pigments for synthetic resins and the like, and superconductive carbon black (Ketjen Black) may also be used. good. Further, the mixing ratio of the epoxy resin and carbon black is such that carbon black is mixed within a range of 2 to 30 parts with respect to 100 parts of the epoxy resin. This is because if the carbon black is 2 parts or less, the entire counter electrode 62 does not function as a conductor, and if it is 30 parts or more, it becomes difficult to disperse the carbon. Although not shown, the counter electrode 62 is partially grounded.

Outlet 1 of instrument panel pad 1 of said counter electrode 62
Recesses 64 are formed at positions corresponding to 0, 11, and 12, and a buffer plate 65 made of a dielectric material such as high-palon rubber or epoxy resin is fitted in the recesses 64 to even out corona discharge. It is supposed to be generated.

[Discharge electrode means B]

As shown in FIGS. 4 to 6, the discharge electrode means B is the corona discharge electrode 50, the X-axis moving means 20 for moving the corona discharge electrode 50 in the X-axis (horizontal) direction, and the Y-axis (front-back) direction. It is composed of Y-axis moving means for moving and Z-axis moving means 40 for moving in the Z-axis (up and down) direction.

In the X-axis moving means 20, two guide rods 28 extending parallel to the horizontal direction are attached to the base 80.
The guide rod 28 is provided with a turntable 26 for supporting the next Y-axis moving means 30 slidably in the X-axis direction. That is, the support member 23 is attached to the lower surface of the turntable 26, and the guide rods 28 are inserted into the support member 23, whereby the turntable 26 is inserted.
Is slidable.

Further, of the lower surface of the turntable 26, the support member 23
A screwing portion 29 is attached to the left and right sides of the, and one screw shaft 27 is screwed into the screwing portion 29 so that the screw shaft 27 can be screwed and withdrawn. A gear 21a is attached to the right end of the screw shaft 27, and the gear 21a meshes with the gear 21b of the servomotor 25 attached to the right end of the base 80.

Therefore, when the server motor 25 rotates, the gears 21a,
Since the screw shaft 27 rotates via 21b, the turntable 26 moves in the X-axis direction together with the screwing portion 29 screwed to the screw shaft 27.

Next, in the Y-axis moving means 30, the turntable 26
Two bearings 35 are provided on each side of the upper surface. Two screw shafts 31 are rotatably and immovably mounted between the left and right bearings 35, and both shafts 31 extend in parallel to the horizontal direction. A gear 36a is attached to the front and rear of each screw shaft 31, and the square gear 36a is meshed with a gear 36b of the servo motor 32 attached to the rear end of the base 80.

A screw member 34 extending over both shafts 31 is screwed onto the two screw shafts 31, and a Y-axis arm 33 extending forward is attached to the center of the screw member 34. Y
The following Z-axis moving means 40 is fixed to the front end of the shaft arm 33.

Therefore, even in the Y-axis moving means 30, the servo motor 32
Rotation of the gear 36, the screw shaft 31, and the screwing member 34.
Are transmitted in this order, and the Z-axis moving means 40 moves in the Y-axis direction.

Next, in the Z-axis moving means 40, a fixed table 41 is vertically fixed to the front end of the Y-axis arm 33. Two guide rods 42 are provided at the front end of the fixed table 41.
Are fixed, and both rods 42 extend in parallel in the vertical direction.

A sliding member 44 straddling the guide rods 42 is slidably attached to the guide rods 42, and a female screw (not shown) is formed at the center of the sliding member 44. A screw shaft 46 extending upward is screwed into the female screw, and the screw shaft 46 is directly connected to a rotary shaft 47 of a servo motor 45 attached to the upper portion of the fixed table 41.

On the other hand, a Z-axis arm 43 extending downward is fixed to the central portion of the sliding member 44 at the upper end thereof,
A discharge electrode 50 for corona discharge is always held in a substantially vertical state at the lower end of 3.

Therefore, when the servomotor 45 is rotated, the screw shaft 46 is rotated and the Z-axis arm 43 is moved through the sliding member 44.
Also, the discharge electrode 50 moves up and down.

The discharge electrode 50 arranged in the atmosphere has a rod-shaped gripped portion 51 made of stainless steel and having a diameter of about 2 mm and a rod-shaped gripped portion 51 also made of stainless steel and having a diameter of about 6 mm attached to the tip of the gripped portion 51. It is composed of a spherical discharge tip 52.
As described above, the grasped portion 51 is always grasped by the Z-axis arm 43 in a substantially vertical state, and is not tilted when moved by the moving means 20, 30, 40.

As shown in FIG. 7, it is desirable to provide a mesh-shaped shield tube 53 made of stainless steel or the like around the discharge electrode 50. This is because the shield tube 53 can prevent radiation of high frequency noise during corona discharge.

[High-frequency applying means C]

As shown in FIGS. 4 and 7, a high frequency applying means C including a high frequency oscillator 16 and a high voltage transformer 17 is connected to the counter electrode 62 and the discharge electrode 50. Further, as a countermeasure against high frequency noise, the high frequency oscillator 16 is also directly grounded.

The high frequency oscillator 16 has 20 to 30 KHZ and the maximum output of 35.
Tantech products that generate 0 W high frequency (Product name H
VO5-2) is used. The high voltage transformer 17 boosts the high frequency output of the high frequency oscillator 16 to generate electrodes 62, 50.
It is for applying a high voltage between them, and a product (trade name Spar C) manufactured by Tantech Co. is also used.

[Control unit D]

A control circuit (not shown) using a computer or the like is incorporated in the control unit D, and the discharge electrode 5 is included in the control circuit.
A movement program for controlling the operation of the X, Y, Z axis moving means 20, 30, 40 for moving 0 to the vicinity of the surface of the instrument panel 1, a program for controlling the start and stop of the operation of the high frequency applying means C, etc. Is written.

The control unit D and the high-frequency applying means C are arranged at a considerable distance with the base 80 sandwiched therebetween, and the power supplies are independent and independent. This is to prevent the computer of the control unit D from malfunctioning due to the high frequency noise leaking from the high frequency applying means C. Further, for the same reason, the cord connecting the high frequency oscillator 16, the high voltage transformer 17 and the discharge electrode 50 needs to be securely shielded.

As shown in FIG. 5, an exhaust means E for exhausting gases such as ozone generated during corona discharge treatment is arranged at a position behind the counter electrode means A in the base 80. ing.

Now, a method of performing corona discharge treatment on the instrument panel pad 1 by using the corona discharge treatment device configured as described above will be described.

First, if the molded instrument panel pad 1 has a mold release agent or dirt or the like caused by manual work, it is desirable to perform a pretreatment of washing these with an organic solvent such as trichloroethane. This is to ensure the corona discharge treatment.
However, if there is no release agent or stain, or if it is slight, no pretreatment is necessary.

Next, as shown in FIGS. 1, 2, 4, and 5, the instrument panel pad 1 is fitted to the counter electrode 62 of the counter electrode means A. At this time, the counter electrode 62 is formed of a material containing a non-conductive epoxy resin powder 62a and a conductive carbon black powder 62b, and the front surface or the whole thereof is substantially the same as the three-dimensional shape of the back surface of the instrument panel pad 1. Since they are formed in the same shape, the entire front surface of the counter electrode 62 surely contacts the entire back surface of the instrument panel pad 1.

That is, the counter electrode 62 of this embodiment formed by melting a non-conductive substance containing a conductive substance, pouring it into the back surface of the instrument panel pad 1 and curing the same is much more effective than the conventional method. It is easy to manufacture, and it does not cover the conductive layer that becomes an extra thickness.
The shape of the back surface of the instrument panel pad 1 can be exactly matched.

Therefore, almost the entire instrument panel pad 1 formed of the dielectric PP resin is electrically and effectively coupled to the counter electrode 62, and the gap between the counter electrode 62 and the discharge electrode 50 can be constantly reduced. It will be possible. As a result, corona discharge is likely to occur from the discharge electrode 50.

Now, assuming that a resin mold is made by pouring a resin into the inside of the instrument panel pad 1 and a conductive layer serving as a counter electrode is coated on the surface of the instrument panel, the entire thickness of the conductive layer is inevitable. It becomes large, and an error occurs between the inside of the instrument panel pad 1 and the inside. Therefore, when the instrument panel pad 1 is arranged thereon, an air layer may be generated between the instrument panel pad 1 and the counter electrode 62.
This air layer acts as an insulating layer and makes corona discharge less likely to occur. In this embodiment, this air layer is surely eliminated to realize the electrical coupling.

Next, after the evacuation means E is operated, the control unit D is turned on to set the moving means 20, 30, 40 of each axis in the discharge electrode means B to the start position of the corona discharge treatment. At this time, the gripped portion 51 of the discharge electrode 50 is always supported in a vertical state, and the discharge tip portion 52 is located above the left end of the front edge of the instrument panel pad 1 by about 10 mm.
Located at mm intervals.

Next, when the high frequency oscillator 16 of the high frequency applying means C is operated, the high frequency output is boosted by the high voltage transformer 17,
A high frequency of 28 KV is applied between the counter electrode 62 and the discharge electrode 50. Then, corona discharge is generated in the atmosphere between the upper surface 2 and a portion of the discharge tip 52 facing the upper surface 2, and the corona discharge treatment of the upper surface 2 is started.

The X, Y, and Z axis moving means 20, 30, and 40 are servo motors 2 that operate based on a control signal from the control unit D.
The discharge electrodes 50 move in the respective directions by the rotations of 5, 32, and 45, and move near the surface of the instrument panel pad 1.

The moving speed of the discharge electrode 50 can be arbitrarily set within the range of 1 to 250 mm / sec under the discharge conditions, but in this embodiment, sufficient corona discharge treatment effect and shortening of treatment time are required. 150 mm / s
ec.

By the corona discharge treatment involving the reciprocating movement as described above, the entire surface of the instrument panel pad 1 is subjected to the corona discharge treatment, and the adhesiveness of the adhesive or the like is improved. The improvement of the wettability by the corona discharge treatment of this embodiment is based on the conventional flame treatment (flame treatment).
Is about the same.

In addition, as shown in FIG.
When passing above 0, 11, 12 and the pans 6, 7, the discharge electrode 50 is moved downward by the difference in the height thereof, so that the inner surfaces of the outlets 10, 11, 12 and the pans 6, 7 are discharged. The bottom of the plate, the corner portions 9 and 13 and the like are surely subjected to corona discharge treatment.

The phenomenon of the corona discharge treatment is that a large amount of electron flow generated by the discharge collides with the synthetic resin (PP in this embodiment), the collision energy partially destroys the bond between carbon and hydrogen, and the surface of the synthetic resin is destroyed. It is considered to be for oxidization and ionization for activation.

Further, since the corona discharge spreads from the discharge tip 52 with a very uniform discharge pattern as shown in FIG. 7, the treatment range of the surface of the instrument panel pad 1 at each time is considerably wide, and the circle with a diameter of 50 to 60 mm is It is fully processed. This is because the discharge tip portion 52 has a spherical shape (curved surface shape), and therefore the corona discharge is uniformly dispersed without being concentrated at one point (a sharp portion or a corner).

Thus, according to the corona discharge treatment device of the present embodiment,
Large-scale equipment such as vacuum tank, vacuum pump, valve mechanism, carrier gas, etc. in the conventional plasma processing and preparation time required for decompressing the vacuum tank are no longer necessary, and corona discharge processing is generated in the atmosphere by the discharge electrode 50 etc. Then, the surface of the instrument panel pad 1 made of the PP resin can be modified only by moving it. Therefore, not only the equipment cost and equipment space can be significantly reduced, but also the processing time can be shortened.

Further, since the discharge electrode 51 having at least the discharge tip portion having a curved shape is moved along the surface of the instrument panel pad 1, the corner portions 5, 8, 9, 13 can be surely treated.

The present invention is not limited to the above embodiment,
For example, the following modifications can be made and embodied.

(1) As the non-conductive material of the counter electrode 62, polyester resin, silicon rubber, gypsum, or the like can be used in addition to the epoxy resin of this embodiment.

(2) The carbon black powder 62b is SA which is hard carbon in addition to the acetyl carbon black of this embodiment.
F, ISAF, HAF, FET that is soft carbon,
You may use HMF, GPF, etc.

(3) As the conductive material of the counter electrode 62, in addition to the carbon black powder 62b of the present embodiment, metal powder of gold, silver, copper or the like, metal fiber, or the like can be used. A mixture of metal powder and carbon black powder 62b may be used.

(4) The structure of the X, Y, Z axis moving means 20, 30, 40 in the discharge electrode means B may be changed, or an articulated robot or the like may be used instead of them. Alternatively, the counter electrode means B may be provided with a three-dimensional moving mechanism, and the instrument panel pad 1 may be moved to be brought close to the discharge electrode 50.

(5) In addition to the instrument panel pad 1, the present invention requires automotive bumpers, automobile moldings, mudguard fenders for motorcycles, as well as painting, bonding, printing, etc. after molding of various industrial equipment and household products. Not only can it be used as a counter electrode manufacturing method for all three-dimensional resin molded products, but it can also be used as a counter electrode for two-dimensional resin molded products.

EFFECTS OF THE INVENTION As described above in detail, according to the present invention, it is troublesome to perform a resin mold forming operation and a conductive layer coating on the surface of the resin mold, which has been conventionally performed in the forming operation of the counter electrode for corona discharge treatment. Corona discharge treatment can be performed on the surface shape of the counter electrode by a simple operation of pouring a molten material containing a non-conductive material containing a conductive material onto the inner surface of the molded product and curing the material by reaction hardening. It has an excellent effect that the shape can be fitted exactly to the inner surface shape of the molded product, and corona discharge can be easily generated.

[Brief description of drawings]

FIG. 1 is a sectional view showing the instrument panel pad and the counter electrode means by cutting it back and forth, FIG. 2 is a sectional view showing the instrument panel pad by cutting it to the left and right, FIG. 3 is a perspective view of the instrument panel pad, and FIG. 4 is a corona discharge. FIG. 5 is a right side view of the processing apparatus, FIG. 5 is a right side view of the same, FIG. 6 is a plan view of the Y-axis moving means, and FIG. 7 is a schematic view showing the connection between the discharge electrode and the high frequency applying means. Non-conductive substance ... 62a Conductive substance ... 62b Counter electrode ... 62

Claims (3)

[Claims] 1. A conductive material (6a) is added to a non-conductive material (62a).
The material containing 2b) is melted, and the melted material is poured into the inner surface of the molded product (1) to be reacted and hardened to form the counter electrode (6).
2) The method for producing a counter electrode for corona discharge treatment, characterized in that 2. The method for producing a counter electrode for corona discharge treatment according to claim 1, wherein the non-conductive substance (62a) is polyester resin, epoxy resin, silicone rubber, or gypsum. 3. The method for producing a counter electrode for corona discharge treatment according to claim 1, wherein the conductive substance (62b) is metal powder or carbon black powder.