JPS62115039A - Method for treating surface of polylefin molding - Google Patents

Abstract

PURPOSE:To modify the surface of a molding uniformly and rapidly, by washing the surface of a polyolefin molding with an org. solvent and moving an electrode for corona discharge along the profile of the surface of the molding while generating corona discharge. CONSTITUTION:The surface of a polyolefin molding 1 having a three-dimensional structure is washed with an org-solvent (e.g,., trichloroethylene) to remove oils, fats and dust and at the same time to swell the surface. The molding 1 is placed on an opposing electrode D fixed on a stand A of a device for a corona discharge treatment. The device is evacuated and a high frequency applying means B is actuated to irradiate the molding 1 with corona discharge from the discharging top 52 of an electrode 50 for corona discharge. At the same time, the electrode 50 is moved along the profile of the surface of the molding 1 to modify the surface of the molding 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for surface treatment of a polyolefin molded article whose surface is coated with a paint, printing ink, adhesive, or the like.

(Prior art) Polyolefin synthetic resins such as polypropylene (PP) and polyethylene (PE), or polyolefin synthetic rubbers such as ethylene-propylene-diene ternary copolymer rubber (EPDM) and ethylene-propylene copolymer rubber (EPM) Since it does not have a polar group in its molecule, it has poor adhesion even if paint, printing ink, adhesive, etc. are applied to the surface of the molded product made of the resin or rubber.

Therefore, when painting, adhering, printing, or the like is applied to the surface of the molded article, it is necessary to perform a modification treatment on the surface as a pretreatment to improve adhesion.

Conventionally, physical modification treatments such as plasma treatment and corona discharge treatment, or chemical modification treatments such as dichromic acid-sulfuric acid mixture treatment and trichlorethylene cleaning have been adopted as modification treatments for the polyolefin molded products. There is.

The above plasma treatment is carried out by introducing plasma gas into a nitrogen tank, so almost the entire surface of the molded product can be modified at once, and is used as a pretreatment for automobile bumpers, moldings, etc.

Furthermore, the corona discharge treatment described above can modify the properties of a molded product by passing the molded product between electrodes that are close to each other, and is therefore used exclusively for the modification of thin film-like molded products.

However, no conventional technique has been found for corona discharge treatment of a molded article having a three-dimensional shape.

(Problems to be Solved by the Invention) Unlike plasma processing, corona discharge treatment does not require a vacuum chamber and can be performed in the atmosphere, making it possible to process a large number of objects in a short time. There is an advantage.

However, in conventional corona discharge treatment, the distance between the electrodes is
There was a problem in that it was extremely narrow, about 4 liters, so that a three-dimensional molded object with a three-dimensional effect could not be inserted through it.

In particular, as mentioned above, polyolefin molded products
Because it is difficult for paints, printing inks, adhesives, etc. to adhere, it is difficult to form three-dimensional shapes even though the above-mentioned chemical modification treatment and corona discharge treatment can be used in combination to achieve effective modification treatment in a short time. In the case of polyolefin-based molded products, no technology has been found to treat them with corona discharge treatment, so at present, surface treatment methods that combine the above chemical modification treatment and corona discharge treatment have not been adopted. be.

Structure of the Invention (Means for Solving the Problems) Therefore, the present invention provides a method for cleaning the surface of a polyolefin molded product with a three-dimensional shape with an organic solvent, and then cleaning the surface of the polyolefin molded product with a three-dimensional shape, and then cleaning the surface of the polyolefin molded product, and then cleaning the surface of the polyolefin molded product with an organic solvent, and then cleaning the surface of the polyolefin molded product with a three-dimensional shape. By adopting a surface treatment method for a polyolefin molded article, which is characterized by moving a corona discharge electrode relatively along the surface shape of the molded article while generating a corona discharge in the vicinity of the molded article,
This is an attempt to solve the above problems.

Note that the polyolefin molded product having a three-dimensional shape to be modified according to the present invention refers to polyolefin synthetic resins such as PP and PE, or EPDM and EP.
It is a molded product made of polyolefin synthetic rubber such as M, and has a three-dimensional uneven shape excluding a planar sheet body.

(Function) By cleaning the surface of the above polyolefin molded product with an organic solvent, dust, oil and fat bones, etc. are removed, and the surface is swollen by the organic solvent, making it easy to be modified by corona discharge treatment. .

Next, by performing a corona discharge treatment using an electrode suitable for the surface shape of the polyolefin molded article, such as a shape of a discharge part such as a sphere, rod, or plane, the surface can be uniformly and quickly modified. It becomes possible.

(Example) An example embodying the present invention will be described below with reference to FIGS. 1 to 8.

First Example: [Polyolefin molded product] As shown in Fig. 1, the polyolefin molded product whose surface is treated in this example is an automobile instrument panel band (hereinafter abbreviated as instrument panel) made of PP resin. ) 1 with vinyl chloride (PV
C) It becomes an instrument panel product by adhering a resin skin sheet.

The instrument panel 1 has protruding corner portions 5 at the boundary between the top surface 2 and the front surface 3, the boundary between the top surface 2 and the side surface 4, etc., and the radius of the corner portion 5 is about 6 squares.

Furthermore, two shallow dish portions 6.7 are provided on both left and right sides of the upper surface 2 of the instrument panel 1. Therefore, a convex corner part 8 is formed at the upper edge of the dish part 6.7, and a concave corner part 9 is formed at the bottom edge of the dish part 6.7.
The radius of is approximately 6■-.

Further, two ventilation/air conditioning air outlets 11 and 12 are formed on the left and right sides of the front surface 3, and a side defroster air outlet 10 is formed at the left end of the upper surface 2. Each outlet 10, 11, 12 has a substantially rectangular shape, and the edges and four corners have a radius of 6 to 15.
A crane corner portion 13 is formed.

Next, the surface treatment apparatus used in this example will be explained.

[Cleaning equipment]

FIG. 7 shows a cleaning device used in this embodiment, and the bottom of a metal cleaning tank 71 with a rectangular cross section has a solubility parameter that is the same or similar to that of the instrument panel 1 that is the object to be treated, that is, the PP resin. The container is filled with an organic solvent 72 (trichlorethylene in this example). A heater with a temperature control function is immersed in the organic solvent 72 so that the organic solvent 72 is maintained at its boiling point temperature (87° C. in the case of trichlorethylene).

In addition, a metal net 74 is stretched in the center of the cleaning tank 71 for loading the objects to be processed, and cooling water is circulated inside the upper part of the cleaning tank 71. A cooling pipe 75 having holes for cleaning is provided, and the vapor of the organic solvent 72 is cooled on the surface of the cooling pipe 75 and returns to the inner bottom of the cleaning tank 71.

As the organic solvent filled in the cleaning tank 71, it is preferable to select a solvent having a solubility parameter that is the same as or close to the solubility parameter of the polyolefin that is the base material of the object to be treated.

That is, when treating PP resin (solubility parameter = 8.0) as in this example, trichlorethylene (solubility parameter = 9.2), trichloroethane (9,6), dichloroethylene (9° , 1), ethyl chloride (9,2), pentachlorethylene (9,4
), chlorinated organic solvents such as tetrachlorethylene (9°3), ethylene chloride (9,7), ethylene dichloride (9,8), and acetyl chloride (9°5); benzene (9,2), toluene ( 8,9), xylene (8,9)
, 8), chlorotoluene (8, 8), chlorhenzene (
Aromatic organic solvents such as 9,5) are suitable.

[Corona discharge treatment equipment]

As shown in FIGS. 2 to 4, the corona discharge treatment apparatus used in this example is composed of the following means, which are mounted on the top and side of the two-stage step-like base A. They are arranged separately.

That is, the corona discharge treatment device is installed on the left shelf 14 of the base A.
A high frequency oscillator 16 and a high frequency transformer (
(not shown); an electrode moving means C disposed on the second stage of the base A; and a corona discharge electrode 50 held by the electrode moving means C. The counter electrode means fixed to the first stage of the base A, and the electrode moving means C fixed to the right side of the base A.
and a control unit E arranged to control the.

In the high frequency application means B, the high frequency oscillator 16 has 20 to 3
A Tantic product (product name: rHV05-2J) that generates a high frequency wave of 0 KH2 and a maximum output of 350 W is used.

The high voltage transformer boosts the high frequency from the high frequency oscillator 16 and applies a high voltage to the corona discharge electrode 5o.
l) is used.

The electrode moving means C is an X-axis moving means 20 for moving the corona discharge electrode 50 in the X-axis (left and right) direction indicated by arrow X, and also for moving it in the Y-axis (front and back) direction indicated by arrow Y. Y-axis moving means 30, and X-axis moving means 40 for moving in the Z-axis (up and down) direction, also indicated by arrow Z.
It is composed of.

In the X-axis moving means 20, two guide rods 28 are fixed on the base A in parallel and horizontal direction.

A turntable 26 for supporting the Y-axis moving means 30 is provided on the guide rod 28 so as to be slidable in the X-axis direction. Note that a threaded portion 29 is provided on the bottom surface of the turntable 26.
A support member 23 is attached, and the two guide irons 28 are inserted through the support member 23.

Further, a screw shaft 27 is screwed into the screw portion 29 between the two guide irons 28, and a gear 21a is attached to one end of the screw shaft 27. This gear 21a is the gear 21b of the rotating shaft 22 of the servo motor 25.
The rotation of the servo motor 25 is transmitted to the screw shaft 27.

Therefore, the rotation of the servo motor 25 is caused by the rotation of the turntable 26.
, and the Y-axis moving means 30 moves in the X-axis direction.

As shown in FIG. 4, two bearings 35 are provided on both sides of the turntable 26 in the Y-axis moving means 30, and two screw shafts 31 are rotatably attached to these bearings 35. It is attached so that it cannot move forward or backward, and both shafts 31 extend parallel to each other and in the horizontal direction. A gear 36 is attached to one end of each of these screw shafts 31, and is connected to a rotating shaft 37 of a servo motor 32.

A threaded member 34 spanning the same shafts 31 is threaded onto the two screw shafts 31, and one end of a Y-axis arm 33 extending forward is attached to the center of the threaded member 34. Further, a Z-axis moving means 40 is provided at the other end of the Y-axis arm 33.
is fixed.

Therefore, also in the Y-axis moving means 30, the servo motor 32
The rotation is transmitted to the gear 36, the screw shaft 31, and the threaded member 34, so that the Z-axis moving means 40 moves in the Y-axis direction.

In the Z-axis moving means 40, a plate-shaped fixed table 41 is vertically fixed to the other end of the Y-axis arm 33. Two guide rods 42 are fixed to the front side of the fixed table 41 in parallel and vertically, and a sliding member 44 is slidably attached to both the guide rods 42 so as to straddle them.

(not shown) provided in the center of the sliding member 44
A screw shaft 46 extending upward is screwed into the screw shaft 46 , and the screw 46 is directly connected to a rotating shaft 47 of a servo motor 45 installed on the top of the fixed table 41 .

On the other hand, the upper end of a downwardly extending biaxial arm 43 is fixed to the center of the sliding member 44, and the corona discharge electrode 50 is held at its lower end.

Therefore, when the servo motor 45 is rotated, the screw shaft 46 is rotated, and the Z-axis arm 43 and the corona discharge electrode 50 are moved up and down via the sliding member 44.

In addition, the control unit E includes a control i′ using a microcomputer, etc.
111 circuit (not shown) is incorporated, and the control circuit controls the operation of the X, Y, and Z axis moving means 20, 30, and 40 in order to move the corona discharge electrode 50 near the surface of the instrument panel 1. A program and a program for controlling the start and stop of operation of the high frequency application means B are written.

Furthermore, an exhaust means F is provided at the inner lower part of the base A for exhausting gas such as ozone generated during the corona discharge treatment.

〔electrode〕

A corona discharge electrode 50 held at the tip of the Z-axis arm 43 is connected to the high frequency oscillator 16. This electrode 50 is made of stainless steel, and as shown in FIG. 5, it has a rod-shaped gripped part 51 with a diameter of about 2WIN, and a spherical shape with a radius of about 2.5 as at the tip of the gripped part 51. The discharge tip portion 52 is made up of a

As shown in FIG. 5, a large number of hemispherical protrusions 53 are formed on the surface S of the discharge tip 52 for the purpose of improving current collection efficiency.

Next, on the upper surface of the first stage of the base A, below the corona discharge electrode 50, a counter electrode means is provided.

In this counter electrode means, as shown in FIG.
A ladder-shaped electrode stand 61 is arranged on the base A. A counter electrode base material 62 formed to match the shape of the back surface of the instrument panel 1 is provided on the electrode stand 61, and a counter electrode 63 is formed on the surface by metal plating, vacuum deposition, sputtering, conductive paint coating, etc. The coating is formed by pasting aluminum foil or other means.

The back surface of the instrument panel 1 is brought into contact with the upper surface of this counter electrode 63, and each air outlet 10.11 of the instrument panel 1
．． A buffer plate 15 made of rubber or the like is applied to the back surface of the electrode 12 to prevent the counter electrode 63 from being exposed.

Note that the counter electrode base material 62 can be obtained, for example, by using the instrument panel 1 as a mold, pouring an epoxy resin into the back surface thereof, and causing the resin to react and harden.

A method for modifying the surface of the instrument panel 1 using the cleaning device and corona discharge treatment device configured as described above will be described.

First, the instrument panel 1 was mounted on the net 74 in the cleaning tank 71. The inside of the cleaning tank 71 is filled with trichlorethylene vapor because the trichlorethylene has been heated to its boiling point temperature in advance, and the surface of the instrument panel 1 is cleaned by the vapor to remove dust, oil and fat bones, etc. At the same time, the surface is swollen by the trichlorethylene and becomes susceptible to modification by the corona discharge treatment described below.

After the instrument panel 1 that had been cleaned for about 30 seconds in the cleaning tank 71 was taken out, it was heated and dried to evaporate the trichlorethylene attached to the surface.

Next, as shown in FIG. 2.3.6, the instrument panel 1 was fitted onto the counter electrode means, and the counter electrode 63 was brought into contact with the back surface of the instrument panel 1.

After the exhaust means F is operated, the control unit E is turned on, and the electrode moving means B is turned on.

After the Y- and Z-axis moving means 20, 30, and 40 were set at the start position of the corona discharge treatment, the high frequency application means B was activated. At this time, the distance between the tip of the corona discharge electrode 50 and the instrument panel 1 is 10n+, and the corona discharge electrode 50
A high frequency of 28 KV is applied between the electrode 63 and the counter electrode 63.

Corona discharge is irradiated onto the instrument panel 1 from the discharge tip 52 of the corona discharge electrode 50, and the corona discharge process starts.

The x-, y-, and z-axis moving means 20, 30.40 are moved by the rotation of a servo motor 25°32.45 based on a signal from the control unit E, and the corona discharge electrode 50 is moved from the instrument panel.
The robot moves from the right end to the left end at a speed of 1 to 25 cm/sec.

Then, the corona discharge electrode 50 reciprocates in the lateral direction near the surface of the instrument panel 1 several times.

On the surface of the instrument panel 1 that has been subjected to the corona discharge treatment, some of the bonds between carbon and hydrogen in polypropylene molecules are broken, and the molecules are ionized or oxidized and activated.

Therefore, when a skin or the like is adhered to the surface of the instrument panel 1 that has been subjected to the corona discharge treatment, surface modification effects such as improved adhesion are exhibited.

Furthermore, in this embodiment, since the entire discharge tip 52 is formed into a spherical curved surface S, corona discharge is generated uniformly without being concentrated at one point.

Moreover, corona discharge occurs even if the distance between the corona discharge electrode 50 and the counter electrode 63 is relatively large.
The method of the present invention can also be applied to three-dimensional molded articles for which it has been said that corona discharge treatment has no practical effect.

Further, since a large number of hemispherical protrusions 53 are formed on the discharge tip 52 of the corona discharge electrode 50 of this embodiment, corona discharge is generated in all directions and the discharge distance is also increased.

Therefore, even if the moving speed of the corona discharge electrode 50 of this embodiment is increased, a sufficient discharge treatment effect can be obtained, and this is highly effective in improving productivity.

Furthermore, unlike plasma treatment, the corona discharge treatment of this embodiment does not require a vacuum chamber, vacuum pump, piping system, carrier gas, etc., and therefore the treatment process can be automated.

Second Example: Figure 8 shows an automobile side protection molding (hereinafter simply referred to as molding) whose surface is treated according to this example.
81, and a corona discharge electrode 82 held at the tip of a Z-axis arm 43 of a corona discharge treatment apparatus for subjecting the molding 81 to corona discharge treatment.

The above-mentioned molding 81 is obtained by extrusion molding EPDM, and a Tedra film made of a three-layer film of polyvinyl fluoride, polyester, and vinyl chloride is attached to the top and bottom surface of the molding product. be.

The electrode 82 is made of stainless steel, and includes a rod-shaped gripped portion 83 with a diameter of approximately 2fi, and a discharge electrode 84 as a rod-shaped discharge portion having the same diameter as the gripped portion 83 at its tip. It is configured. The discharge electrode 84 is bent into a shape substantially equal to the cross-sectional shape of the molding 81. Therefore, by using the electrode 82, uniform corona discharge treatment can be performed on each surface of the molding 81.

The molding 81 is mounted on the net 74 in the cleaning tank 71 used in the first embodiment, left for 30 seconds, and its surface is washed with a thin air of trichloroethane, and then the molding 81 is heated and dried. Trichloroethane adhering to the surface was evaporated.

Thereafter, using a corona discharge treatment apparatus to which the rod-shaped discharge electrode 84 was attached, the surface of the molding 81 was subjected to corona discharge treatment in the same manner as in the first embodiment.

The discharge electrode 84 of this embodiment is a long and thin rod-shaped electrode.
Since the molding 81 is bent into a shape that is almost the same as the cross-sectional shape of the molding 81, each surface of the molding 81 can be uniformly treated with corona discharge, and the discharge distance is also increased.

Therefore, as in the case of the first embodiment, the corona discharge electrode 82 of this embodiment can obtain a sufficient discharge treatment effect even if its own moving speed is increased, and has a great effect on improving productivity. demonstrate.

Note that the present invention is not limited to the above embodiments,
For example, it is also possible to implement it as shown below.

(2) The corona discharge electrode is not limited to the above-mentioned spherical or rod-shaped electrodes, and depending on the shape of the polyolefin molded product, it is also possible to use a planar electrode, a pin electrode, or the like.

(2) The device is not limited to the device of this embodiment, and an industrial robot or the like may be used.

■ The polyolefin molded product is not limited to the injection molded product of the first embodiment or the extrusion molded product of the second embodiment,
The present invention is also applicable to molded products obtained by various molding methods such as blow molding and transfer molding.

Effects of the Invention As detailed above, the method of the present invention makes the surface of a polyolefin molded article susceptible to modification by cleaning it with an organic solvent, and then the shape of the discharge part is changed to a sphere, a rod, or a plane. Corona discharge treatment is performed using an electrode suitable for the surface shape of the polyolefin molded article.

Therefore, the present invention exhibits an excellent effect in that the surface of a polyolefin molded article to be coated with a paint, printing ink, or adhesive can be uniformly and quickly modified.

[Brief explanation of drawings]

Figure 1 is a perspective view of the instrument panel pad, Figure 2 is a perspective view of the instrument panel pad.
The figure is a front view of the corona discharge treatment device, FIG. 3 is a partially broken side view of the corona discharge treatment device, FIG. 4 is a top view of the Y-axis moving means, and FIG. 5 is the corona discharge device used in the first embodiment. A side view of the tip of the electrode, FIG. 6 is a sectional view of the counter electrode means, FIG. 7 is a sectional view of the cleaning device, and FIG. 8 is a perspective view showing the tip of the molding and corona discharge electrode of the second embodiment. It is a diagram. 1...Instrument panel pad, 81...Mall, 50.82...Corona discharge electrode, 71...Cleaning tank. Patent applicant Toyoda Gosei Co., Ltd. Agent
Patent attorney On 1) Boxuan-ku Hoku Kuchison

Claims (1)

[Claims] 1. After cleaning the surface of a polyolefin molded article with a three-dimensional shape with an organic solvent, a corona discharge electrode whose discharge part is in the shape of a sphere, rod, or plane is placed near the molded article. A method for surface treatment of a polyolefin molded article, characterized in that the molded article is relatively moved along the surface shape of the molded article while generating a corona discharge. 2. The method for surface treatment of a polyolefin molded article according to claim 1, wherein the organic solvent has a solubility parameter that is the same as or similar to that of the polyolefin.