JPS58225132A - Corona discharge treatment of plastic formed product - Google Patents

Abstract

PURPOSE:To perform titled treatment of improved effect through increasing effective electric energy density with reduced gas quantity, by feeding an oxygen-free gas into a hood containing the discharge electrode, followed by exhausting the gas through the opening provided on the electrode. CONSTITUTION:For example, a plastic film 6 is fed from the direction of an arrow B to the metal drum 1 revolving in the direction of A, and is drawn out in the direction C. The discharge electrode 3 is shielded from the ambient air using a hood 2 followed by introducing into the hood an inert gas (e.g., nitrogen) through the opening 7 to effect oxygen-free state. The electrode 3 is provided with a gas intake 5, and, while exhausting the inert gas forcedly out of the hood through the tube 4, a high voltage of high frequency is applied between the electrode 3 connected to a high voltage generator and the metal drum 1 covered with the film 6 such as of polyester, thus performing the objective corona discharge treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the corona discharge treatment effect to the extent that it can be fully satisfied at the actual production level.

Discharge of plastic molded materials is a technology that has been used for a long time, and has become an indispensable technology for surface modification of plastic films (including sheets, the same shall apply hereinafter) such as polyethylene films and polypropylene films. There is. Furthermore, the various plastic molded products described below are also considered to be a useful means for improving quality, and the range of benefits and applications is expected to expand in the future.

However, in order to do so, it is necessary to improve the processing efficiency itself by corona discharge treatment and explore its possibilities.Although extensive improvement research has been carried out so far, it is still not sufficient.

For example, in Japanese Patent Publication No. 48-17747, organic solvents are
gl! Although a technique has been described in which chemical changes are promoted at the discharge surface by supplying solvent to plastics, it is not suitable for the current situation where residual solvent in plastic moldings is a problem. Also JOURNAL 0FAPPLIED PO
LYMER5CIENCE Vol 15PP1861
S-1875 (1971) describes that corona discharge treatment is performed under an atmosphere surrounded by inert gas, and it is suggested that the influence of activation or deterioration on the surface of plastic molded products may occur. Techniques have also been proposed in which corona discharge treatment is performed in place of a low-acid cumulative atmosphere, but conventional methods, such as the method disclosed in Japanese Patent Publication No. 56-18881, require a large amount of inert gas and are costly. However, in the method of JP-A No. 57-28684 (corona discharge technology under an inert atmosphere for a running film), in order to block the large sword that gets caught along with the film, Although a special shield structure is required and the installation is complicated, the amount of inert gas supplied is unnecessarily large, and a completely or almost completely inert atmosphere is not formed, resulting in a low treatment rate. I had to settle for the level. For this reason, taking film as an example, it has the disadvantage that high-speed processing is not possible, resulting in a significant drop in productivity.On the other hand, if you try to increase the processing effect by using low-speed processing, poor appearance will occur due to surface damage. However, defects such as an increase in shiblocking have appeared, and it can only be said that it is unsatisfactory at the level of actual production.

The present invention was made with attention to this situation, and aims to develop a technology that does not require special and large-scale equipment and does not require the consumption of large amounts of gas in the Shield River. It was completed as a result of intensive research. However, the corona discharge treatment method according to the present invention involves continuously transporting a plastic molded article into a corona discharge treatment apparatus in which at least one pair of electrodes are arranged facing each other and the discharge side electrode is surrounded by a hood. Let's release Nita! To carry out the treatment, while introducing a gas other than air or an acid atmosphere into the hood, the corona discharge treatment is performed while the gas is discharged and actively discharged from the side electrode or its vicinity to the outside of the hood. The gist lies in what it does.

Plastic molded products to which the method of the present invention is applied include:
In addition to the above-mentioned films, fibers, pipes, tapes,
Examples include long objects such as woven fabrics and non-woven fabrics, and if the present invention is applied to the case where these long objects are carried into a corona discharge treatment device in the longitudinal direction and passed through it to perform corona discharge treatment, the effect will be However, even if other molded products are subjected to corona discharge treatment while moving at a constant speed, great technical effects can be obtained by applying the present invention. be able to. Polymers constituting the molded product include thermoplastic resins such as polyamide, linear polyester, polyolefin, polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polystyrene, polyvinyl alcohol, phenolic resin, urea resin, and melamine resin. , unsaturated polyester resin, and thermosetting resin such as Huan rice bran. Moldings made from these resin numbers contain stabilizers, lubricants, anti-blocking agents, antifogging agents, and ultraviolet absorbers.
111. Materials that may contain additives such as twist retardants, clarifying agents, antioxidants, +IIY4 light agents, antistatic agents, dyes, pigments, etc., and do not adversely affect the implementation of corona discharge. are included in the scope of the present invention, whether alone or in combination.

The structure and effects of the present invention will be clarified below based on the drawings of the embodiment (however, the structure and arrangement of the discharge side 1! poles, the shape of the hood, etc. shown in the drawings are only representative examples).
Further, since the drawings show only nine examples of application to the film snack film, it is within the technical scope of the present invention to make changes to the design provided that they do not go against the spirit of these descriptions.

FIG. 1 is a sectional view of a main part showing the concept of implementation of the present invention, the second figure is a sketch of the discharge side electrode, and 1 in the figure is a metal drum;
2 is an electrode hood, 8 is a discharge side electrode, 4 is a gas exhaust pipe, 5
6 indicates a gas inlet, and 6 indicates a running film. That is, the film 6 is rotated in the direction indicated by the arrow B with respect to the metal trim 1 rotating in the direction indicated by the arrow.
The lightning is introduced from the direction of the arrow C and is further pulled out in the direction of the arrow C.
A high voltage of several thousand to tens of thousands of V is applied between the ill electrode 8 and the metal trim 1 covered with polyester, epoxy resin, ceramic, chlorosulfonated polyethylene, EP river, etc., at a high frequency of several hundred KG/S. Due to the influence of the envy pressure corona generated by the film 6, for example, in the case of a natural large sword, ozone and nitrogen oxides are generated and carbonyl groups and carboxyl groups are generated on the surface of the film 6. becomes polarized. However, in this example, the corona discharge direction (C is entirely shielded from the atmosphere by the ``FFL pole hood 2'', and the upper part of the ``FFL pole hood 2 has a crotch opening 7 for inert gas to be injected into the 7-door 2. A gas inlet 5 is provided in the discharge side electrode 8 so that the atmospheric gas is discharged from the nuclear inlet 5 to the outside of the hood. Various effects depending on the type of inert gas (for example, N2 gas improves oxygen barrier properties due to the formation of nitrogen-containing groups, CO2 gas improves adhesiveness due to improved corona discharge effect, etc.) f
μ can be used. The concept of the illustrated discharge side type fijii 8 is as shown in FIG. It is formed into a slit shape along the slit, and gas exhaust pipes are connected to the bottom of the slit at appropriate intervals, and the end of the gas exhaust t5 is connected to a gas suction pump (not shown). .Appropriate cover plates may be attached to both ends of the slit in the longitudinal direction (the front side and the opposite side (however, the opposite side is not shown in the figure) in the longitudinal direction of the slit for the purpose of preventing gas suction from the rear end surface.

By the way, a small amount of entrained air layer is formed on the surface of the film 60 that enters at a fairly high speed in the direction of arrow B, and it is not possible to simply create an inert gas atmosphere inside the hood as in the past. However, the surface of the film 6 itself still retains the air surrounding it, making it impossible to enjoy the effects obtained by the present invention.

However, by adopting the above configuration, on the film entry side of the discharge couple fM8, as shown in FIG. Then, the accompanying air layer 8 is entrained and disturbed by the suction air flow K1 like an ejector, or is disturbed so as to protrude in front of the discharge gap by the suction pressure of the air flow K1. Near the bottom of the gas inlet 5, the disturbed accompanying air layer sucked into the discharge gap flows into the intake airflow from the delivery side of the film 6.
The internal airflow is further disturbed and is sucked into the gas inlet 6 together with 1 and N2. In this way, the air layer 8 is destroyed and eliminated, and at the same time at least half of the corona discharge area (the latter half of the film advance).
This makes it possible to maintain a complete inert gas atmosphere.

Figures 4 to 10 show various structural examples of the discharge side electrode used in the present invention and U! The behavior of the suction gas in the tank structure is i,
Since this is an explanatory drawing that does not exhaustively show the sage side, it is left to the discretion of the person implementing the present invention to appropriately combine these.

Figure 4 has the same structure as the 'WL pole shown previously, and an inert gas C (hereinafter simply referred to as gas) is sucked in as shown by the arrow. In the example shown in FIG. 5, the gas inlet is deflected in a direction opposite to the direction in which the film enters. As a result, the intake airflow from the inlet side (left side in FIG. 4) does not easily flow into the gas inlet 6 υ, and the agitation and removal of the entrained air layer is carried out more -N than in the example of FIG. 4. Furthermore, since the passage distance of the intake airflow from the outlet side (right side in the figure), in other words, the discharge area from which the accompanying air layer is removed becomes longer, corona discharge is performed better. Figure 6 shows an example in which 411 gas collecting electrodes (hereinafter referred to as collecting electrodes) 3' are added to the tip of the electrode 8, which is made of a conductive metal sintered body or a porous material such as steel wool. . In this case, the collecting electrode 3' functions as a gas collecting port to the gas inlet 6, and gas is sucked in from the entire tip of the collecting electrode 3' and collected at the gas inlet 6 outside the hood. is discharged to. Therefore, the accompanying empty qC layer is removed smoothly and completely, and the gas atmosphere in the corona discharge area is stabilized. Figure 7 shows an electrode divided into front and rear parts (left and right in the figure, the same below), with a gas collection electrode having the same configuration as in Figure 6 on the front side, and a normal 'fIL without a gas suction function on the rear side. It has poles and integrates them. The example of Jin was designed based on the idea of destroying and removing the first air layer at the beginning of the approach, and in that sense it is the fifth
It is expected that the same effect as in the illustrated example will be obtained. Figure 8 shows an example in which the electrode is divided into eight parts, with the gas collection electrode shown in Figure 6 placed in the center and regular electrodes placed at both front and rear ends. This is an example of a pole arrangement for gas collection, but the configuration is completely reversed.

However, both methods exhibit the same effect of destroying and removing the accompanying air layer and preserving the ambient air in the corona discharge area. 1st
The θ diagram is an example in which a gas suction pipe 9 having an opening facing the film is provided on the film entrance side of the normal electrode 8 (left side in the drawing), and the gas suction pipe 9 is provided on the film entrance side of the pipe (on the left side in the drawing) to the Gas Kenjin pipe 9. 1 is formed in the gas flow sucked from the left side), and 2 is formed in the gas fN sucked from the film delivery side of the electrode (right side in the figure) through the discharge gap at the bottom of the electrode. , K2 makes the adjoint empty layer t
Lol! The stirring is eliminated and the same effect as above is achieved.

FIG. 11 shows an example in which two normal electrodes are installed independently and side by side, and the inhaled gas is discharged from between the electrodes to the outside of the hood, so that the inert gas flows in the direction shown in the figure.

In each of the above embodiments, the downstream side of the electrode was explained as being flat, but it may be pointed at an acute angle or an obtuse angle, rounded in a hemispherical shape, or it may be pointed in the direction of film passage.
Items that are repeated more than once (e.g. serrated canes, etc.)
), and in short, any electrode structure may be used as long as it does not cause any inconvenience in forming an inert gas flow on the corona discharge treated surface of the plastic molded material passing through.

Although the configuration of the present invention is as described above, it is free to add additional means to enhance the corona discharge treatment effect.
All such means are included in the present invention, regardless of whether they are known or not. Examples of such means include humidifying the plastic molded product at the same time as the corona discharge or in advance.Specifically, pre-treatment with flame, or if the plastic molded product is a long object such as a film, In this case, it is recommended that the long object be preheated by passing it through a temperature control roll, or that the metal dowel itself be warmed. Since the corona discharge treatment is preheated by
1. Next, examples and comparative examples of the present invention will be described.

Using the apparatus shown in FIG. 1, a biaxially stretched film (thickness: 20 μm) of tactical polypropylene (polyoxyethylene alkylamine-〇, mixed by Six Jusha Co., Ltd.) was subjected to corona discharge treatment. The treatment conditions and results are shown in Table 1. As Comparative Example 1, corona discharge treatment was performed in the atmosphere (without nitrogen gas spraying), and as Comparative Example 2, corona discharge treatment was performed in the atmosphere while nitrogen gas was injected into the electrode cover (however, nitrogen gas was not sprayed in 1 and 1). A discharge treatment was performed. The respective treatment conditions and results are also listed in Table 1.

In the example, a high current was obtained even at the same voltage as in Comparative Examples 1 and 2, and extremely excellent results were obtained in terms of adhesive properties.Especially in comparison Clearly better results were obtained in Example 2 (simply a low acid cumulative atmosphere).

In addition, when we re-experimented Example and Comparative Example 2 by increasing the oxygen concentration in the electrode cover by more than 1, the results in Comparative Example 2 were similar to those in Comparative Example 1, but the good results in Example were maintained. .

Since the configuration of the present invention is the same as described above, various effects can be obtained as summarized below.

The large gC layer that is carried along with the surface of the ill plastic molded article into the corona discharge treatment section is agitated by the gas flow that is sucked into the opening provided at or near the discharge side electrode.
In addition, since it is sucked into the gas inlet together with the a gas and discharged to the outside of the hood, it is reliably destroyed and eliminated. Therefore, a discharge section free from static electricity can be reliably formed with a small amount of gas.

(2) As a result, the Me fi1 pumping power value per unit area increases dramatically, and the corona discharge treatment effect improves due to the increase in effective power density.

13) Also, the unique effects of each atmosphere, for example kJ'N
The effect of forming amino groups and imino groups (improving oxygen barrier properties) on the surface of the plastic molded product due to the presence of the two gases is extremely highly inhibited.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram showing the implementation ooze of the present invention, Fig. 2 is a conceptual diagram showing the discharge used in the present invention (1111%f, i-dream sketch,
Figure 3 is an explanation showing the destruction-resolving ooze of the accompanying static layer.
4 to 11 are explanatory diagrams exemplarily showing the electrodes and gas flows used in the present invention. 1...Metal drum 2...%) Extreme hood 8...
・Discharge (ti11 electrode 4...gas exhaust pipe 5...
・Gas inlet 8... Accompanied static layer 9... Gas inlet pipe 1B#mA *nlJjm engineering, oh

Claims (1)

[Claims] (1) When plastic molded articles are continuously carried into a corona discharge treatment fIJ device in which at least one pair of electrodes are arranged facing each other and a discharge side electrode is surrounded by a hood, a corona discharge treatment is performed. A plastic molded article characterized in that a gaseous body excluding air and oxygen is introduced into the hood, and a corona discharge treatment is performed while the gaseous body is actively discharged from the discharge side electrode or its vicinity to the outside of the hood. corona discharge treatment method.