JPS58225133A - Corona discharge treatment of plastic formed product surface - Google Patents

Abstract

PURPOSE:To effectively perform titled treatment without requiring any large equipment and a large quantity of a shielding gas, by blowing at a specific speed a mixed gas with a composition other than that of the air on the corona discharge-treating surface of a plastic formed product. CONSTITUTION:For example, a plastic film 6 is fed from the direction of B to the metal drum 1 revolving in the direction of A, and is drawn out in the direction C. Along with shielding from the air the entire corona-discharged space containing the discharge electrode 3 using a cover 2, while providing the electrode 3 with a gas ejecting exit 5 and blowing an inert gas (e.g., N2, CO2) on the film surface through a gas-feeding tube 4 to replace the ambient air by the inert gas, a high-frequency voltage is applid between the electrode 3 connected to a high voltage generator and the 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.

Electric discharge treatment of plastic molded products is a technology that has been practiced for a long time, and is especially indispensable for surface modification of plastic films (V-) such as polyethylene films and polypropylene films (hereinafter the same shall apply). It has become. In addition, the plastic molded products described below are considered to be a useful means for improving quality, and the scope of application of these benefits is expected to expand in the future.

However, in order to achieve this, it is necessary to improve the treatment efficiency itself by corona discharge treatment and explore its possibilities.Although extensive improvement research has been carried out so far, it cannot be said that it is sufficient.

For example, Japanese Patent Publication No. 4g-17747 describes a technique for promoting chemical changes on the discharge surface by supplying an organic solvent to the discharge section, but residual solvent in the plastic molded product is a problem. It is not suitable for the current situation.

Matata JOURNAL 0FAPI'LIED POLYM
ER5CIENCE VOL15 PP1865~1
87fi (1971), it is described that the electric discharge treatment is performed under an inert gas atmosphere, and if the effect of activation or deterioration on the surface of the plastic molded product is suggested, the atmospheric atmosphere may be reduced, for example. Techniques for performing corona discharge treatment in place of an oxygen atmosphere have also been proposed;
Conventional methods, such as the method disclosed in Japanese Patent Publication No. 6-18881 (1988), require a large amount of inert gas, leading to high costs; (Corona discharge technology under an inert atmosphere) requires a special shield structure to block the large sword that is entrained by the film, which complicates the equipment operation, but we must not be complacent. did not become. For this reason, taking film as an example, it has the disadvantage that productivity is significantly reduced because it cannot be processed at high speed.On the other hand, if you try to increase the processing effect by using low speed processing, the appearance will be poor due to surface damage. This leads to defects such as an increase in shiblocking caused by the occurrence of oxidation, and it can only be said that it is completely 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 for shielding. It was completed as a result of intensive research. However, the corona discharge treatment method according to the present invention requires at least one pair of opposing! In a method of carrying out corona discharge treatment by continuously transporting plastic moldings into a corona discharge treatment apparatus in which electrodes are arranged, discharge (electrostatic discharge from Jlltffti or its vicinity onto the treated surface of the plastic molding) is performed. Single or mixed gas consisting of the composition [specifically, air with a suitable amount of a part of the static charge composition removed, a part of the static charge composition added with an appropriate amount to static electricity, and furthermore, N2 + H2m A' +
It involves spraying a single or mixed gas such as C02m012 (excluding static composition (hereinafter abbreviated as inert gas for convenience)), and performs corona discharge heat stretching. The gist of this is that one speed of the blower is determined to be at least one factor of the speed at which the plastic molded article is introduced.

Plastic molded products to which the method of the present invention is applied
・In addition to the above-mentioned films and sheets, fibers,
Examples include long items such as vibrators, tapes, woven fabrics, and non-woven fabrics.
If the present invention is applied to the case where these long objects are conveyed longitudinally into a corona discharge treatment device and passed through it to perform corona discharge treatment, the effect will be dramatically exhibited, but other molding Even if it is a material, if it is subjected to corona discharge and treatment while moving at a constant speed, great technical effects can be obtained by applying the present invention. Polymers constituting the molded product include thermoplastic resins such as polyamide, linear polyester, polyolefin, polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polystyrene, and polyvinyl alcohol; phenolic resin, urea resin, and mecumin resin. , unsaturated polyester resin, furan resin, etc. *? +Ij'-forming VFJII11 is used. In addition, stabilizers, lubricants,
Additives such as anti-blocking agents, anti-fogging agents, ultraviolet absorbers, refractory agents, transparency removers, antioxidants, light stabilizers, antistatic agents, dyes, pigments, etc. All materials that do not adversely affect implementation are included in the scope of the present invention, regardless of whether they are used singly or in combination.

The structure and effects of the present invention will be clarified below based on the drawings of the embodiments, but the structure and arrangement of the discharge side electrodes, the shape of the cover, etc. shown in the drawings are only representative examples.
Further, since the drawings merely show an example of application to a plastic film, it is within the technical scope of the present invention to change the design on the condition that it does not go against the spirit of these descriptions.

FIG. 1 is a cross-sectional view of a main part showing the concept of implementing the present invention, and FIG. 2 is a perspective view showing a part of the discharge side electrode, in which 1 is a metal drum, 2 is an electrode cover 8, and gIllden, ItM
, 4 is a gas supply pipe, 5 is a gas outlet, and 6 is a running film. That is, the film 6 is introduced from the direction of arrow B into the metal drum 1 rotating in the direction of arrow A, and is further pulled out in the direction of arrow C. A pole 8 and a metal drum 1 covered with polyester, epoxy resin, ceramic, chlorsphlephonated polyegulene, EP evaporation, etc...1
The high frequency of several white KC/S is several thousand or the enemy V's high 1! Under the influence of the high-pressure corona generated by applying pressure, for example, in the natural atmosphere, ozone and nitrogen oxide are generated, creating carbonyl groups and carboxyl groups on the surface of the film 60, and the surface becomes polarized. be done. However, in this example, the entire atmosphere of corona discharge is
At the same time, the gas outlet 5 is installed on the discharge side 'FtW8 to spray inert gas toward the surface of the film 60, so various types of gas can be used depending on the type of inert gas. Effects (for example, in the case of N2 gas, the formation of nitrogen-containing groups improves adhesion, especially with nitrogen-containing objects, and that the effective discharge area of the discharge electrode is expanded, improving treatment efficiency. In the case of CO2 gas, it improves corona discharge efficiency. further improvement in adhesion, etc.) can be obtained. The concept of the illustrated discharge side type FM8 is shown in FIG. It is formed into a slit shape along the slit, and gas supply pipes 4 are connected to the bottom of the slit at appropriate intervals. Therefore, the gas supply pipe 4
The inert gas supplied under pressure through the corona discharge section is dispersed in the longitudinal direction within the slit section and is ejected almost uniformly from the gas ejection ports 5, so that the atmosphere in the corona discharge section is replaced with inert gas. Appropriate cover plates may be attached to both longitudinal ends of the slit (the front side and the opposite side in the figure, however, the opposite side is not shown in the figure) for the purpose of preventing gas diffusion from the end faces.

However, a slight static layer is formed on the surface of the film 60 that enters at a fairly high speed in the direction of arrow B, and even if the atmosphere in the corona discharge section is replaced with an inert gas, The surface of the film 6 itself still retains an atmospheric atmosphere, and the effects of the present invention cannot be enjoyed if the inert gas is simply spouted out aimlessly. Therefore, if the inert gas is strongly ejected as shown in Figure 8 and the accompanying air layer 7 is destroyed and dispersed by the jet stream 8, the atmosphere in the corona discharge area can be made inert.
1.1 We thought that it might be possible to completely replace the gas depending on the gas, and various studies were conducted. As a result, it was found that the intrusion speed of the accompanying air layer 7 was an important factor, and it was found that the moving speed of the air layer 7 (input speed of the plastic molded product) is at least 11 or more, preferably 10 or more, and It has been found that by forming the jet flow 8 preferably at a speed of 40q6 or more, the entrained air layer can be destroyed and dispersed to the extent that there is no practical problem. The conveying speed of the brick molded product is generally 1 to 500 m/min.

By adopting such conditions, it becomes possible to destroy and disperse the accompanying static layer, and at the same time, it becomes possible to protect the vicinity of the corona discharge part from being flooded with an inert gas atmosphere. MLm shown in the figure
The cover 2 is expected to have a function of protecting the electrode 8 from mechanical impact and a function of suppressing the accompanying flow as much as possible, rather than having a function of maintaining the atmosphere. Therefore, when implementing the present invention, sometimes the electrode cover 2
It may be easier to remove the cover, but in order to reduce the amount of inert gas consumed, it is desirable to reconsider its function as an atmosphere retainer.For example, as shown in Figure 4, the lower end of the cover 0111) at the same time, the guide c#1
When inert gas is introduced into the cover 2 from 0, the gas flows in the direction of the arrow so as to be converged along the inner surface of the slope 9.
A gas curtain effect is produced at the entrance of the cover 2. In other words, the intrusion of the accompanying air layer is blocked on the inlet side, and 'WIL
The value of Goku Cover 2 will further improve.

However, on the exit side of the film 6 (right side 1 in Figure 4), the gas inside the cover 2 is discharged along with the running film 6, so there is a problem with the sealing performance or the intrusion at the entrance. (Ill do which number, 16
1 life≠5, and as mentioned above, in the sense of reducing the amount of inert gas quenched 1, it is meaningful to distribute oil in the same way as on the inlet side. In order to exhibit the above-mentioned sealing function on the inlet and outlet sides of the cover 2 at a minimum of 1 g, the film surface must be applied at a speed of at least 12 mm or more, preferably 10 times or more relative to the film running speed. It is possible to release it. Regarding the ejection speed of inert gas, only the lower limit side has been described for both the gas ejection port and the inlet/outlet of the cover 2, but there is no need to set a strict limit on the upper limit, and at most the ejection amount and ejection effect are limited. For the former, the travel speed is 10
As a rough guideline, the travel speed should be at most 10 times, preferably 5 times or less, the traveling speed.

Figures fi to 26 show the discharge 011 used in the present invention.
1 [This is an explanatory diagram showing examples of each structure of the poles and the behavior of ejected gas in the structure, and does not exhaustively show examples, so it is at the discretion of the person implementing the present invention to combine these appropriately. It is left to the.

Figure 6 has the same structure as the electrode shown previously, and inert gas C (hereinafter simply referred to as gas) is ejected as shown by the arrow (in the example in Figure 6, the gas outlet 5 is connected to the film). In other words, the accompanying air 9cN on the film is opposite to the approach direction.
It is deflected to the left side in Figure C of the entrance side so that the gas is blown directly against the entrance of I. It is also useful to flow the gas along the inlet and outlet sides (right side in the figure) of the electrode 8 as shown by arrows and E;
As shown in FIG. 8, the object of the present invention may be achieved by this alone. Therefore, FIG. 18 is considered to be an embodiment of the present invention, and in the following examples as well, the formation of a gas flow along the stain electrode may be added as an auxiliary or main component if necessary. Figure 7 shows a gas diffusion electrode (hereinafter simply referred to as a diffusion electrode) 3' made of a porous gas diffusion material such as conductive metal sintered steel wool or wire mesh added to the tip of the electric fM8. This is an example. In this case, the gas ejection port 6 functions as a gas supply port for the diffusion electrode W33', and the gas is ejected from the entire tip of the electrode. Therefore, the gas is ejected smoothly and the gas atmosphere in the corona discharge section is stabilized. 8th
The figure shows an example in which the formation of a gas flow along the electrodes is added to the example of FIG. 7. In Figure 9, the electrode is divided into front and rear parts (left and right in the figure, the same below), with a gas ejection electrode having the same configuration as in Fig. 7 on the front side, and a normal 'i electrode without a gas ejection function on the rear side. These are integrated. This example was designed based on the idea of destroying and diffusing the accompanying air layer at the beginning of the approach.

Figure 10 shows an example in which the electrode is divided into eight parts, the gas ejection electrode of Figure 7 is provided in the center, and one pole is normally placed at both the front and rear ends.
Figure 1 shows an example in which a normal electrode is placed in the center and gas ejection electrodes are placed at both front and rear ends, and the configuration is completely reversed. However, both methods exhibit the same effect of destroying and diffusing the accompanying air layer and protecting the atmosphere of the corona discharge section. 12th
The figure shows an example in which the central normal electrode in FIG. 11 is provided with a gaff outlet 5 having the same configuration as that in FIG. 5, and the above effect is even more pronounced. FIG. 18 has already been explained.

Fig. 14 shows nine gas ejection pipes 11 arranged above and before the electrode 80, and the gas ejected directly below from the pipe 11 descends along the electrode, producing the same effect as described in Fig. 6.18. demonstrate. Although the examples shown in FIGS. 6-18 and 8 are explained as examples in which the pipe 11 is not provided, in these examples, gas is ejected from above the electrode cover (described above) toward the entire electrode cover. Each of the above-mentioned gas flows can be formed by this. However, in the example shown in FIG. 14, gas is ejected in a concentrated manner through the pipe 11, so that small waves of gas can be effectively utilized.

Figures 16 to 28 are examples of a method in which gas is ejected on one side and sucked on the other, and there is no difference from the previously described examples in terms of ejecting gas.
In order to suck this gas from other parts, one reason is that the gas after being blown out is moved in a specific direction, thereby strengthening the protection of the discharge part.

Second, a part of the ejected gas is recovered, and in some cases, it can be mixed and reused as is in the ejected gas, so that the gas cost can be reduced. However, if the suction (Ill) becomes less than atmospheric pressure, there is a risk that the associated hole electrode layer will be pulled toward the lower end of the tttt rod, so it is necessary to maintain it at a high voltage or higher. This is an example in which the gas suction port 5' is used, and a part of the gas ejected from the former is consumed for destruction and dispersion of the accompanying static layer, and the remaining part runs parallel to the film to create the atmosphere of the discharge section that forms the core a. After forming, the gas is collected from the gas suction port 5'. Fig. 16 shows an example in which sintered metal is added to the ejection port 5 and suction port 5', and Figs. 17 and 18 correspond to Figs. 11 and 12. However, the above-mentioned effects are fully exhibited in both examples in which gas is ejected and sucked as shown in the figure.

FIG. 19 shows an example in which the plate 12.12 is disposed close to the front and rear of the Fl rod 8. The lower end of the plate 12 is bulged and a gas ejection pipe 11 is provided. and t
&8 and play) When gas is ejected from the pipe 11 while sucking the inside of the gap 12 from above to form an upward gas flow, a part of the ejected gas is released from the aforementioned bulge, Particularly on the inlet side, the accompanying air layer is destroyed and diffused. Then, the inside fills the lower surface of the electrode 8, or is sucked directly upward. Figure 20 shows the 15th mark in the center of 'ffL dedication 8.
An example in which a gas suction port 5' similar to the one shown in the figure is formed, the 21st plate is an example in which sintered metal is attached to the front side, and the 22nd plate is provided with a plate 12 only on the inlet side, and the plate 12 has an electrode 80 gap. In this example, gas is ejected from the bottom of the FiL pole 8, and gas is also ejected from the entire bottom of the FiL pole 8, while the gas suction pipe 14 is placed over the swollen part of the plate 12 to suck the ejected gas. A portion of the air layer is pushed into the suction tube 14. Figure @2B is an example of the hairstyle shown in Figure 12.18, in which sintered metal is added to the tip of the gas electrode 8, which was originally integrated, and the central gas outlet 5 is formed by passing the sintered metal through to the tip. However, the gas suction ports 5' on both sides are stopped in front of the sintered metal. The gas that exits the spout 5 flows in the direction of the arrow and reaches the suction port 5'.
However, the gas may be finally ejected from the suction port 5' side and the gas may be sucked from the spout port 541J1.

@Figures 24 to 26 show examples in which two electrodes are installed independently, and two or eight or more of the electrodes shown in Figures 6 to 28 may be installed as they are, or the mutual relationship of multiple electrodes may be utilized. It is recommended that each of the above-mentioned effects be made more remarkable by the following. First, in Figure 24, two unprocessed electrodes are lined up,
This is an example in which gas flows downward from the opening and the gas is ejected as shown in the figure. Figure 25 is an example in which the idea of Figures 20 and 24 is applied, and the gas suction ports 5' in Figure 20 are connected to both sides of the electrode. It is composed of Finally, FIG. 26 is an example in which two electrodes, the seventh electrode and the second electrode in FIG. 6, are arranged so as to leave a gas suction gap 16, and the ejected gas flows in the direction shown by the arrow.

In each of the above embodiments, the lower end of the electrode was explained as being flat, but it may be pointed at an acute angle or an obtuse angle, rounded into a hemispherical shape, or in two or more steps in the film passing direction. Repeated patterns (e.g. serrations, etc.)
), in short, any electrode stacking may be used as long as it does not cause any inconvenience in spraying inert gas against 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 heating the plastic molded product at the same time as the corona discharge or in advance.Specifically, pretreatment with flame, or if the plastic molded product is a long piece such as a film. If the object is a metal drum, it is recommended to preheat the long object through a temperature control roll or warm the metal drum itself. However, in the present invention, since the inert gas to be blown is sufficiently preheated by contact with the electrode, an extremely high corona discharge treatment effect can be obtained without adding the above-mentioned means.

Next, examples and comparative examples of the present invention will be described.

Using the apparatus shown in Fig. 1, a biaxially stretched film (1'N 20 #t) of tactical polypropylene (polyoxyethylene alkylamine = 0.6 weight ratio mixed)
n) corona discharge treatment was performed. The treatment conditions and results are shown in Table 1. As Comparative Example 1, corona discharge treatment (without nitrogen gas spraying) was performed in a large electric current, and as Comparative Example 2, corona discharge treatment was performed while nitrogen gas was injected into the electrode cover (but without nitrogen gas spraying). A discharge treatment was performed. Husband 4's 3Jp conditions and results are also listed in Table 1.

In the example, even at the same voltage as in Comparative Example 1.2, a surface current was obtained, and extremely excellent results were obtained in terms of adhesive properties. In particular, clearly better results were obtained than in Comparative Example 2 (simply a low acid cumulative atmosphere).

In addition, when the oxygen concentration in the electrode cover was increased to 1% and both the Example and Comparative Example 2 were tested, the results in Comparative Example 2 were similar to those in Comparative Example 1, but the results in Example were better than t. was sustained.

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

fl) The atmospheric layer carried into the corona discharge treatment section along with the surface of the brick molded product is reliably destroyed and dispersed by the inert gas blown onto the rock surface. Therefore, it is extremely unlikely that large -i-/+1 will be mixed into the atmosphere of the corona discharge area. Since it is a gas other than gas and oxygen, the gas is ejected from the corona discharge surrounding atmosphere and the oxygen concentration is low, resulting in a low oxygen concentration in the discharge wL atmosphere width.

(3) Therefore, the discharge is uniformly performed over the entire surface of the N pole, the effective electrode area and the pole area are expanded, and the current value and power value per phase area are increased. In other words, the current increases dramatically even under the same voltage, and the corona discharge treatment effect improves due to the increase in effective power density.

14) In addition, the unique effects of each atmosphere, such as the effect of forming amino groups and imino groups on the surface of the plastic molded product (effect of improving oxygen barrier properties) due to the presence of two gases, are extremely highly exhibited.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram showing the implementation status of the present invention, Fig. 2 is a sketch of the discharge side electrode used in the present invention, Fig. 8 is an explanatory diagram showing the state of destruction of the accompanying atmospheric layer, and Fig. 4 is as much as possible in 1. An explanatory diagram showing an example of the bar, and FIGS. 5 to 26 are explanatory diagrams illustrating the electrodes used in the present invention and the flow of ejected gas.

Claims (1)

[Claims] +11 Corona formed by at least one pair of [1 facing each other #
[When plastic moldings are continuously carried into the processing equipment and subjected to corona discharge treatment, the speed at which the plastic moldings are carried is adjusted to increase the corona discharge heat blood of the plastic moldings from the discharge 0IIK pole or its vicinity. 1. A corona discharge treatment method for the surface of a plastic molded article, characterized in that the corona discharge treatment is performed while spraying a single gas or a mixture of gases having a composition other than air at a speed of 1 inch or more.