JPH01138242A - Surface modification of polymer resin - Google Patents

Abstract

PURPOSE:To modify a polymer resin so that its surface may be excellent in adhesiveness and long-term stability and that it may be free of defects such as blocking, by treating the surface of the polymer resin with a high-voltage discharge under specified conditions. CONSTITUTION:A film 1 of a heat-resistant polymer resin (e.g., aromatic polyimide) of a glass transition point >=100 deg.C, a melting point >=300 deg.C or a max. allowable temperature in long-term continuous use >=121 deg.C is supported on the surface of a drum electrode 4 opposed to a high-voltage application electrode 3 comprising a metal pipe whose outer surface is coated with a 0.1-5mm-thick dielectric (e.g., glass) and which is cooled by passing a coolant (e.g., water) through its inside, said electrode 4 having a diameter at least twice as large as that of the electrode 3 and being coated with the same dielectric as that of the application electrode 3, in a discharge treatment zone 9 having a gas atmosphere of 100-1000Torr containing at least 20mol% rare gas element (e.g., Ar) supplied from a gas feed system 8; a high voltage of a frequency of 20KHz-100MHz is applied to the electrode 3 from a high-voltage source 5 through a transformer 6 to generate a discharge, and the film is treated with this discharge while it is wound around a roller 7 so that the electric power density in the treatment of the polymer resin may be at least 200W.min/m<2>.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for modifying the surface of a polymer resin such as a plastic film, and more specifically to a method for modifying the surface of a heat-resistant polymer resin. be.

[Prior Art] Polymer resins are widely used today, but in various applications, poor adhesion of the surface of the polymer resin has always been a problem. For this reason, surface modification is being investigated using various techniques such as corona discharge treatment, plasma treatment, chemical etching treatment, and sandblasting treatment. Among these, heat-resistant polymer resins have surface properties, especially adhesion, that change significantly depending on the molding conditions compared to other resins, and even if the same processing technology is used, the modification effect is low, making it extremely difficult to modify. It is known as a resin that is difficult to mold.

This means that, conversely, techniques that are effective for modifying heat-resistant polymer resins are also considered to be effective techniques for surface modification of other resins.

Now, several modification techniques have been proposed or implemented for such heat-resistant polymer resins that are difficult to surface modify.

JP-A-61-141532 and JP-A-61-2293
No. 88 proposes a technique for modifying an aromatic polyimide film by treating it with low-temperature plasma. On the other hand, a sandblasting technique has been developed for the aromatic polyimide film and has been widely used. Zarani JP 62-184842, JP 62-162542
discloses a method of mechanically wiping the film surface and a method of corona discharge treatment.

However, each of these methods has the following problems.

First, the method using low-temperature plasma treatment is
As described in 141532, 3X10'~
The treatment is performed by electric discharge generated under a low pressure of 30 Torr, preferably 0901 to 10 Torr, and this method easily forms a stable glow discharge, so surface modification with stable quality can be achieved. There is an advantage that this can be done. However, this low-temperature plasma treatment method requires the creation of a low-pressure atmosphere area;
It requires a vacuum container and a large soot exhaust system, which is extremely costly, and it also takes a long time to adjust the predetermined pressure atmosphere or change the conditions, so there are disadvantages such as high processing costs. be.

On the other hand, sandblasting is widely used because it is a relatively inexpensive process, but with this method, sand remains on the surface of the treated film and in the surface layer, so post-treatment cleaning is required. There are problems such as it is not possible to clearly specify how much cleaning should be done, and quality control during the production process is extremely difficult. Furthermore, although the Sandplus 1 treatment is effective in eliminating variations in adhesiveness and restoring the original adhesive strength of aromatic polyimide, there is a problem in that it is not so effective in improving the adhesive strength itself.

Furthermore, this method blows the sand with strong force, so the sand sticks to the film, and if the film is thin, the sand may penetrate.
There are problems such as pinholes being formed or the surface layer being scraped due to sandblasting, which reduces the strength and elongation of the film. The method disclosed in JP-A-62-184842 is practical, but the reforming effect is quite low.
At least Sand Plus. In addition to being on par with
There is a concern about the adhesion of dust due to static electricity, that is, contamination, and the drawback is that quality control during the production process is difficult. Furthermore, the method according to JP-A-62-162542 is 20 to 3
This is a method in which corona discharge is performed at a discharge power density of 00 W/Tn2/min, and there is a problem that a sufficient reforming effect cannot be achieved with this method. - [Problems to be Solved by the Invention] The present invention was devised in view of the various drawbacks of the prior art, and its purpose is to provide a highly practical polymer resin surface with good quality, cost, and productivity. Processing technology, especially heat-resistant polymer resins, can be modified to have excellent adhesion similar to that modified by low-temperature plasma treatment, and provide a modified surface that is stable over time. The object of the present invention is to provide a method for obtaining a surface modification method that is possible and free from problems such as blocking.

[Means for Solving the Problems] The object of the present invention is to modify the surface of a polymer resin in a gas atmosphere of 100 to 1000 TOrr containing at least 20 mol% or more of a rare gas element. The polymer resin surface is treated by a discharge formed by a high voltage applied between an electrode covered with a dielectric and a dielectric-covered electrode supporting the polymer resin. This is achieved by a method of modifying the molecular resin surface.

All known polymer resins can be used as the polymer resin used in the present invention, but heat-resistant polymer resins are preferred from the viewpoint of modification effects.

Here, as the heat-resistant polymer resin, the glass transition point (TC
I> is 100℃ or higher, or melting point (Tm) is 30
Any polymer resin may be used as long as it satisfies either of the following conditions: 0°C or higher, or a maximum permissible long-term continuous use temperature specified by JISC4003 of 121°C or higher.

These polymer resins include polyarylate which is a condensation product of aromatic dicarboxylic acids of bisphenols, polyallylsulfone represented by polysulfone or polyneedle sulfone, and condensation of benzophenone tetracarboxylic acid with aromatic isocyanate. thermosetting polyimide, aromatic polyimide, aromatic polyamide, aromatic polyetheramide, polyphenylene sulfide, polyallyl ether ketone, liquid crystalline Examples include fluororesins such as polyester, polyamideimide, polytetrafluoroethylene, and tetrafluoroethylene-hexafluoropropylene copolymer. Regarding these heat-resistant polymer resins, please refer to “Latest Heat-resistant Polymers” (supervised by Susumu Mita,
Published by Sogo Gijutsu Center Co., Ltd., 1986. Detailed explanation of the invention.

Among these heat-resistant polymer resins, aromatic polyimide, aromatic polyamide, polyphenylene sulfide, and fluororesin are exposed to high temperatures during molding, resulting in significant changes in surface properties, or the resin is inherently adhesive. Although it is difficult to modify the surface because it does not have
These resins are preferred resins from which excellent modification effects can be obtained by the method of the present invention. In particular, aromatic polyimides, which are condensates of pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, and aromatic diamines such as diaminodiphenyl ether, have a particularly remarkable modification effect by the method of the present invention. This is a preferred resin.

Note that, as a matter of course, additives such as inorganic fillers may be added to these resins.

The form of these polymer resins is not particularly limited, and may be block-like, plate-like, sheet-like, film-like, rod-like,
It can take various forms such as a tube shape, but a film shape is particularly preferable.

Discharge in the present invention involves a high-voltage applying electrode that is made by coating a dielectric material on the surface of a conductor such as a metal tube that has been cooled to about 10 to 100 degrees Celsius by flowing a refrigerant inside, and a The surface on which discharge is formed is formed between the electrode and the electrode for supporting the object, the surface of which is covered with a dielectric material.

The high voltage application electrode preferably has a hollow rod-like M4 structure, and the coolant flowing inside the electrode includes air, Freon, water, etc., and water is preferable. Examples of the dielectric material covering the surface of the conductor include rubber, glass, and ceramic, but glass is preferable, and its thickness is 0.1 to 5.
rnm is preferred.

It is preferable to select a dielectric material that has sufficient withstand voltage for the applied voltage.

The shape of the electrode that supports the object to be processed is selected depending on the form of the object to be processed, but in the case of a long object such as a film, a drum-shaped electrode that can support the object to be processed is preferable. The size thereof is preferably formed to have a diameter twice or more, for example, the diameter of the rod-shaped high voltage applying electrode. It is also important to cover at least the surface of the drum-shaped electrode with a dielectric material, and the thickness and material of the dielectric material are the same as in the case of the rod-shaped electrode.

The number of high voltage applying electrodes and the electrodes supporting the object to be processed does not need to be the same, and it is preferable to provide two or more high voltage applying electrodes for one electrode supporting the object to be processed.

The frequency of the high voltage applied to the high voltage application electrode is 20kHz7
It is preferable to select it in the range of ~100 MHz. 20k
Below Hz, it is difficult to start a discharge, and above 100 MHz, it is difficult to achieve matching. A more preferable frequency is 50kHz to 500kHz.

The electrode supporting the object to be processed may be grounded, or it may be floated above the ground and connected to an output terminal that is a pair of connection terminals to the high voltage electrode of the high voltage power source.

Naturally, it is also preferable that the high voltage power supply has a matching circuit.

In the present invention, the gas composition of the atmosphere is extremely important, and when the above device is used to discharge in a gas atmosphere of 100 to 1000 TOrr containing at least 20 mol% of rare gas elements, the discharge becomes a normal spark discharge ( This discharge is similar to a glow discharge that occurs in a vacuum, rather than a corona discharge (known to those skilled in the art as a corona discharge), and this discharge can supply more power than a spark discharge, and is heat resistant. It has the advantage that it has a remarkable treatment effect on polymers and does not cause drawbacks such as blocking.

The rare gas elements used in the present invention include He, Ne, and A.
r5KrS) (e, Rn, etc., but Ar is most preferred. Such a rare gas must be contained in the atmospheric gas at least 20 mol%.
If the amount is less than mol %, the discharge becomes a spark discharge, which is not preferable because the treatment effect is low like normal corona discharge, and backing or blocking occurs. More preferably, the atmospheric gas contains 50 mol% or more of the rare gas.

Gases that can be used in combination with rare gases include CO2, N
2. Examples include, but are not limited to, organic gases such as methane. However, it is preferable to reduce the amount of 02 gas mixed in as much as possible in order to enhance the processing effect.

It is important to select the pressure of the atmosphere within the range of 100 to 1000 Torr; if it is less than 100 Torr, there will be problems such as the need for a high-grade evacuation device, and if it is more than 1000 Torr, it will be difficult to start discharge.

More preferably, the pressure is selected in the range of 600 to 900 TOrr.

The treatment strength for polymer resins should be selected depending on the polymer resin to be treated, but in the case of heat-resistant polymer resins, it is better to treat with a treatment power density of 200 W-min/Tr12 or more, More preferably 500W”min
/m2 or more, more preferably 1001000W-/-
It is preferable to perform processing at a processing power density of rn2 or higher. In normal corona discharge treatment, if the treatment is performed at a power density of 500 W-min/TT12 or more, the discharge becomes an arc discharge, and pinholes occur in the polymer film to be treated and the coating dielectric of the drum-shaped electrode, but in the method of the present invention, Such a phenomenon is not observed at all, and there is an advantage that a large amount of power can be supplied. It should be noted that the processing power density here is the power divided by the width of the discharge portion (in the axial direction of the drum-shaped electrode) and the processing speed of the film.

Next, the method of the present invention will be explained using an example of an implementation apparatus.

In the figure, the polymer resin film 1 is shown on the feed roll 2.
is sent to the discharge processing section 9. A gas of a predetermined composition is supplied to the discharge treatment section 9 from a gas introduction system 8, and is maintained at a predetermined gas pressure by a simple exhaust device (not shown). In the discharge treatment section, the film 1 is treated by a high-frequency high voltage applied to the high-voltage application electrode 3 from a high-voltage power supply 5 via a matching transformer 6, and by a discharge formed between it and the grounded drum-shaped electrode 4. After
It is wound up on a winding roller 7.

[Example] The present invention will be specifically explained below with reference to Examples, and the physical properties in the Examples were measured by the following methods.

[Method for measuring physical properties, evaluation criteria] ■ After applying a thermosetting acrylic adhesive or poamide adhesive to the treated surface of the treated film, it was laminated with copper foil using a laminator.

■Measurement of Adhesive Strength The adhesive strength between the film and the copper foil was measured using a universal tensile testing machine (manufactured by Toyo Baldwin, Tensilon).

■Evaluation of Blocking Property The treated surfaces of the treated films were placed together, a load of 5,000 yen was applied thereto, and the film was left in an atmosphere at 60°C and 90% for one week.
When this film was taken out and gently rolled, it was judged as good if the films peeled off from each other, difficult to peel off, and bad if the films did not peel off.

Examples 1 to 5, Comparative Examples 1 to 6 Pyromellitic dianhydride and 4
．． An aromatic polyimide film (“Kapton” manufactured by DuPont Azuma) with a thickness of 25 μm and a width of 508 mm formed from a condensate of 4′-diaminodiphenyl ether was prepared.
Using the apparatus shown in the figure, processing was carried out in an atmosphere of Ar gas at 760 Torr, at a film speed of 15 mZmin, and with the processing power density changed as shown in Table 1. As the high voltage application electrode 3, an iron rod-shaped electrode covered with glass of about 1 mm thickness was used, and as the drum-shaped electrode 4, an iron electrode whose drum surface and side surfaces were covered with rubber of about 1 mm thick was used. Water was used in both cases.

As a comparative example, a normal corona discharge treatment using air (tungsten wire was used as a high voltage applying electrode) (Comparative Examples 1 to 3) and treatment in the same manner as in Comparative Example 1 except that Ar was used instead of air. Comparative Examples 4 to 6).

The adhesive strength between each treated film and copper foil was measured using a thermosetting acrylic adhesive, and the results are shown in Table 1.

In addition, in Examples 1 to 5 and Comparative Examples 1 to 6, the drum-shaped ground electrode had a surface length of 600 mm, and the discharge was formed over the entire surface length, so the width of the discharge portion was set to 0°6 m, and the discharge power density was I calculated it.

As shown in Table 1, the films treated by the method of the present invention can be used for flexible printed circuits at the adhesive strength level required for polyimide films (1.5 kca/cm).
), and a remarkable modification effect was observed compared to the untreated film.

On the other hand, in the corona discharge treatments of Comparative Examples 1 to 3 and Comparative Examples 4 to 6, although some modification effects were observed,
Even if the discharge power density was increased, the improvement was slight. Note that when a power of 500 W-min/m2 was applied, the discharge became an arc discharge, dielectric breakdown of the film and the dielectric of the drum-shaped electrode occurred, and pinholes were generated.

The films treated in Comparative Examples 1 to 3 showed strong blocking, and Comparative Examples 4 to 6 showed blocking, although slightly weaker than Comparative Examples 1 to 3. In contrast, almost no blocking was observed in the present invention.

When the treated film of the present invention was laminated to copper foil using a thermosetting polyamide adhesive, adhesive strength similar to that shown in Table 1 was obtained.

Comparative Example 7.8 The aromatic polyimide film used in Example 1 was treated with Ar-N2 (10 mol% to 90 mol%) (Comparative Example 7) and Ar-N2 (19 mol% = 81 mol %) (Comparative Example 8) was treated under the same conditions as in Example 1 at a power density of 100100 OW-/l112.

When the adhesive strength and blocking properties of each treated film were examined, Comparative Example 7 had an adhesive strength of 1.9 kg/Cm, but showed strong blocking. Comparative example 8 is also 2.
0kC]/Cm, but showed blocking although the degree was weaker than in Comparative Example 7.

Example 6 A 26 μm film of tetrafluoroethylene and hexafluoropropylene copolymer was surface-treated, and the atomic composition of the surface measured by photoelectron spectroscopy (using YG Scientific MESCALΔB-5) was F. /C=1.57, O
A fluorine film with a modified surface of /C=0.040 was produced.

Next, the same polyimide film used in Example 1 was used in the same manner as in Example 1, and Ar-C02 (90 mol%:
1001000W-/TT in a mixed gas of 10mol%)
Processed at a power density of 12.

Next, the treated surfaces of both films obtained were brought together, and using a roll laminator whose roll temperature was adjusted to 260'C,
Lamination speed 0.5m/min, linear pressure 10kg/c
Pasted with m. When the adhesive strength between the films of this film was measured, it was found that the adhesive strength was 0.4 kg/Cm or more, and necking occurred in the fluorine film.

In addition, when using untreated polyimide film, 260
When laminating at a roll temperature of 'C, only an extremely weak adhesive strength of several tens of q or less was obtained.

Table 1 [Effects of the Invention] Since the present invention is configured as described above, it is possible to achieve a remarkable modification effect even on resins that are difficult to surface modify, such as heat-resistant polymers, and it is possible to achieve remarkable modification effects using conventional methods. It has superior stability over time compared to other materials, and enables surface treatment without defects such as blocking. Furthermore, since the present invention can be treated under normal pressure or an atmosphere close to normal pressure, it is simple and inexpensive in terms of equipment, and can be said to be a surface treatment technique with extremely high practical effects.

[Brief explanation of the drawing]

The figure shows one example of an apparatus used in carrying out the present invention. 1: Polymer resin to be treated, 3: High voltage application electrode, 4: Support electrode for polymer resin to be treated, 9: Discharge treatment section.

Claims (1)

[Claims] (1) When modifying the surface of a polymer resin, 100-1 containing at least 20 mol% or more of a rare gas element
In a gas atmosphere of 000 Torr, the polymer resin A method for modifying the surface of a polymer resin, the method comprising treating the resin surface.