JPH0474372B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for modifying the surface of a polymer resin such as a plastic film, and more particularly to a method for modifying the surface of a heat-resistant polymer resin film. [Prior Art] Today, polymer resins are widely used;
In various applications, poor adhesion of polymer resin surfaces 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 a marked change in surface properties, especially adhesiveness, 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 use. It is known as a resin that is difficult to modify. 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 technologies have been proposed for heat-resistant polymer resins that are difficult to surface modify.
Or it is being implemented. JP-A-61-141532 and JP-A-61-229388 propose a technique for modifying an aromatic polyimide film by treating it with low-temperature plasma. On the other hand, a sunblasting technique has been developed for the aromatic polyimide film and has been widely used. Furthermore, JP-A-62-184842, JP-A-62-
No. 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 JP-A-61-141532.
10 ^-3 ~ 30 Torr, preferably 0.01 ~ 10 Torr, this method is a process that generates a low pressure. This method easily forms a glow discharge, which is a stable discharge, so it has stable quality. It has the advantage of surface modification. However, this low-temperature plasma treatment method requires the creation of a low-pressure atmosphere region, which requires a vacuum container and large exhaust equipment, resulting in a significant increase in cost. There are problems such as the need for a long time, resulting in high processing costs. On the other hand, sandblasting is widely used because it is relatively inexpensive, but in the case of this method,
Because sand remains on the surface of the treated film or in its surface layer, cleaning is required after treatment, and it is not possible to clearly specify how much cleaning should be done, leading to problems such as extremely difficult quality control during the production process. be. In addition, sandblasting eliminates variations in adhesiveness,
Although it is effective in restoring the original adhesive strength of aromatic polyimide, there is a problem in that it is not very effective in improving the adhesive strength itself. Furthermore, since this method blows the sand with a strong force, the sand sticks to the film, and if the film is thin, the sand may penetrate and create pinholes, or the surface layer is scraped due to sandblasting, which reduces the strength and elongation of the film. There are problems such as a decrease in Unexamined Japanese Patent Publication 1986-
The method disclosed in No. 184842 is practical, but its reforming effect is quite low, at most comparable to sandblasting, and when wiping, there is a concern that dirt may adhere due to static electricity, that is, re-contamination, and the quality during the production process may be affected. The disadvantage is that it is difficult to manage. Furthermore, the method disclosed in JP-A-62-162542 is a method in which corona discharge is performed at a discharge power density of 20 to 300 W/m ² /min.
This method has a problem in that a sufficient reforming effect cannot be achieved. [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 surface of a highly practical polymer resin film with good quality, cost, and productivity. Processing technology, in particular, it is possible to modify a heat-resistant polymer resin film to have the same excellent adhesion as that modified by low-temperature plasma treatment, and to obtain a modified surface that is stable over time, Moreover, it is an object of the present invention to provide a method for obtaining a surface modification method 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 film in a gas atmosphere of 100 to 1000 Torr containing at least 20 mol% or more of a rare gas element. is coated with a dielectric and cooled to 10 to 100°C, and the dielectric-covered electrode supporting the polymer resin film is applied to a discharge formed by a high voltage. Therefore, the surface of the above polymer resin film was heated at 500w.
This is achieved by a method for surface modification of polymer resin films characterized by continuous treatment at a treatment intensity of min/m ² or more. All known polymer resin films can be used as the polymer resin film used in the present invention, but heat-resistant polymer resin films are preferred from the viewpoint of modification effects. Here, the heat-resistant polymer resin film is one with a glass transition point (Tg) of 100℃ or higher, a melting point (Tm) of 300℃ or higher, or the maximum allowable long-term continuous use temperature specified by JISC4003. but
Any polymer resin that satisfies any of the conditions of 121°C or higher may be used. These polymer resin films include polyarylate which is a condensation product of aromatic dicarboxylic acids of bisphenols, polyarylsulfone represented by polysulfone or polyethersulfone, benzophenone tetracarboxylic acid and aromatic isocyanate, and condensates, or bisphenols,
Thermosetting polyimide obtained from the reaction of aromatic diamine and nitrophthalic acid, aromatic polyimide, aromatic polyamide, aromatic polyether amide, polyphenylene sulfide, polyallyl ether ketone, liquid crystalline polyester, polyamideimide, polytetra Examples include fluorocarbon resins such as fluoroethylene and tetrafluoroethylene-hexafluoropropylene copolymers. Regarding these heat-resistant polymer resins, please refer to “Latest Heat-resistant Polymers” (supervised by Susumu Mita,
It is explained in detail in Sogo Gijutsu Center Publishing Co., Ltd., published in 1986). Among these heat-resistant polymer resins, aromatic polyimide, aromatic polyimide, polyphenylene sulfide, and fluorine-based resins are exposed to high temperatures during molding, resulting in significant changes in surface properties or changes in the essential properties of the resin. Although it is difficult to modify the surface of these resins because they do not have adhesive properties, 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 or biphenyl tetracarboxylic dianhydride with aromatic diamines such as diaminodiphenyl ether have been particularly significantly modified by the method of the present invention. This is a preferred resin with recognized effects. Note that, as a matter of course, additives such as inorganic fillers may be added to these resins. Discharge in the present invention involves a high-voltage applying electrode made of a conductor such as a metal tube whose surface is cooled to 10 to 100 degrees Celsius by flowing a refrigerant inside and coated with a dielectric material, and an electrode facing the electrode. The surface on which discharge is formed is coated with a dielectric material and is formed between the electrode for supporting the object to be processed. The high voltage applying electrode preferably has a hollow rod 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 preferred, and its thickness is preferably 0.1 to 5 mm. It is preferable to select a material for the dielectric that has sufficient electrical resistance against the applied voltage. In the case of a long object such as a film, the object to be processed is preferably a drum-shaped electrode that can be supported while being conveyed freely, and its size is, for example, twice or more the diameter of the rod-shaped high voltage application electrode. It is best to form it like this. 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 distance between the high voltage applying electrode and the counter electrode is 0.5 mm or more
It is preferable to make it 10 mm or less. More preferably
It is 0.5 mm or more and 5 mm or less. If this distance exceeds 10 mm, the discharge becomes unstable, and if it is less than 0.5 mm, it is difficult to achieve mechanical precision, resulting in uneven processing,
Processing omissions are likely to occur. The frequency of the high voltage applied to the high voltage application electrode is
It is preferable to select within the range of 20KHz to 100MHz.
Below 20KHz, it is difficult to start discharging, and above 100MHz, it is difficult to achieve matching. A more preferred frequency is 50KHz to 500KHz. The electrode supporting the object to be processed may be installed, or the electrode may be floated above the ground and connected to an output terminal that is paired with a connection terminal for 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 will be 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,
Examples include Ne, Ar, Kr, Xe, Rn, etc., but Ar
is most preferred. Such rare gas must be contained in the atmospheric gas in an amount of at least 20 mol %. If the rare gas content is less than 20 mol%, the discharge becomes a spark discharge, and the treatment effect is low like normal corona discharge.
It is also undesirable because it causes back-up and plotting. More preferably, the atmospheric gas contains 50 mol% or more of the rare gas. Gases that can be used in combination with the rare gas include, but are not limited to, organic gases such as CO ₂ and methane. However, the O ₂ and N ₂ concentrations depend on the stability of the discharge,
From the viewpoint of treatment effects, the amount should be as small as possible, preferably less than 1 mol%, more preferably less than 0.5 mol%. It is important to select the pressure of the atmosphere in the range of 100 to 1000 Torr; if it is less than 100 Torr, there will be problems such as the need for a sophisticated vacuum 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 resin films should be selected depending on the polymer resin film to be treated, but in the case of heat-resistant polymer resin films,
It is preferable to process with a processing power density of 200W・min/m ² or more, more preferably 500W・min/m ² or more,
More preferably, processing is performed at a processing power density of 1000 W·min/m ² or more. In normal corona discharge treatment, if the treatment is performed at a power density of 500 W min/m2 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 the method of the present invention Such a phenomenon is not seen at all, and it has the advantage of being able to supply large amounts of power.
Note that the processing power density here is a value obtained by dividing the output by the width of the discharge portion (in the width 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, a polymer resin film 1 is sent out to a discharge treatment section 9 by a delivery roll 2. A gas having a predetermined composition is supplied to the discharge treatment section 9 from a gas introduction system 8, and is maintained at a predetermined gas level by a simple exhaust device (not shown). In the discharge processing section, the film 1 is subjected to a discharge formed between it and the grounded drum-shaped electrode 4 by a high frequency high voltage applied to the high voltage application electrode 3 from a high voltage power source 5 via a matching transformer 6. After being twisted and processed, it is wound up on a winding roller 7. [Example] The present invention will be specifically explained below with reference to Examples, in which the physical properties during the implementation were measured by the following methods. [Measurement method and evaluation criteria for physical properties] After applying thermosetting acrylic adhesive or poamide adhesive to the treated surface of the treated film,
Laminated with copper foil using a laminator. Measurement of adhesive strength Universal tensile testing machine (manufactured by Toyo Baldwin,
The adhesion between the film and the silver foil was measured using a tensilon (Tensilon). Evaluation of blocking property Put the treated sides of the treated film together, and then
1 in an atmosphere of 60℃90% with a load of 500g
After being left for a week, the film was taken out, and when the film peeled off gently, it was judged as good, if it did not peel off easily, and if it did not peel off, it was judged as poor. Measurement of electrode surface temperature Radiation type surface thermometer (manufactured by Yokogawa Electric
MODEL2542) was used to measure the surface temperature immediately after the discharge stopped. Examples 1 to 5, Comparative Examples 1 to 6 The polymer resin to be treated was an aromatic polyimide film with a thickness of 25 μm and a width of 508 mm formed from a condensate of pyromellitic dianhydride and 4,4-diaminodiphenyl ether. (“Kapton” manufactured by Toray Dupont Co., Ltd.) using Ar gas,
Processing was carried out in an atmosphere of 760 Torr, at a film speed of 15 m/min, and with the processing power density changed as shown in Table 1. In addition, the high voltage application electrode 3 is approximately 1 mm.
The drum-shaped electrode 4 is made of iron rod-shaped electrode coated with glass with a thickness of approximately 1.
Iron electrodes coated with 20 mm rubber were used, and water at 20 to 30°C was used as the coolant. At this time, the electrode surface temperature was 30° C. in all Examples. As a comparative example, ordinary corona discharge treatment was performed using air (tungsten wire was used as a high voltage application electrode) (Comparative Examples 1 to 3), and treatment was performed in the same manner as in 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 both Examples 1 to 5 and Comparative Examples 1 to 6, the drum-shaped ground electrode has a surface length of 600 mm, and the discharge is formed over the entire surface length, so the discharge power density was calculated assuming the width of the discharge portion to be 0.6 m. did. As shown in Table 1, all of the films treated by the method of the present invention exhibit adhesive strength exceeding the adhesive strength level (1.5 kg/cm) required for polyimide films for use in flexible printed circuits, which is significantly greater than that of untreated films. A reforming effect was observed. On the other hand, Comparative Examples 1 to 3 and Comparative Examples 4 to
In the corona discharge treatment No. 6, although a slight modification effect was observed, the improvement was slight even when the discharge power density was increased. Note that when a power of 500W min/ ^m2 is applied, the discharge becomes an arc discharge, and the dielectric material of the film or drum-shaped electrode breaks down.
A pinhole occurred. 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. Furthermore, when the treated film of the present invention was bonded to copper foil using a thermosetting polyamide adhesive, adhesive strength similar to that shown in Table 1 was obtained. Comparative Examples 7 and 8 The aromatic polyimide film used in Example 1 was treated with Ar-N ₂ (10 mol%: 90 mol%) using the apparatus shown in the figure.
(Comparative Example 7) and a mixed gas of Ar-N ₂ (19 mol%: 81 mol%) (Comparative Example 8) were used in Example 1, respectively.
The treatment was carried out under the same conditions as above and at a power density of 1000 W min/m ² . 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 also showed good adhesive strength of 2.0 Kg/cm, but
Blocking was shown although the degree was weaker than in Comparative Example 7. Comparative Example 9 Example 1 except that 90°C hot water was used as the refrigerant
It was processed in the same way. The film had streaks, and the glass covering the high voltage application electrode broke within a few seconds after the discharge started. The electrode surface temperature at this time is
It was 120℃. Comparative Example 10 The same treatment as in Example 1 was carried out except that water as a refrigerant was not flowed through the high voltage application electrode. Immediately after the discharge starts, the glass covering the electrode breaks, and an arc discharge occurs from the broken part.
There was a hole in the film. Immediately after this, the discharge was stopped and the electrode surface temperature was measured and found to be 250°C. Comparative Examples 11 to 13 The treatments were carried out in the same manner as in Examples 1, 3, and 5, except that a -20°C glycol refrigerant (manufactured by Nisso Chemical Industry Co., Ltd., Nibline Z-1) was used as the refrigerant.
The electrode surface temperature at this time was 5°C. As shown in Table 1, sufficient adhesive strength could not be obtained in any case. Comparative Example 14 Processing was carried out in the same manner as in Example 1, except that the processing power density was 300 w·min/m ² . Adhesion strength is 1.4
Kg/cm was insufficient. Example 6 A 26 μm film of tetrafluoroethylene and hexafluoropropylene copolymer was treated with low temperature plasma,
Photoelectron spectroscopy (manufactured by YG Scientific Corporation)
A fluorine film having a modified surface with a surface atomic composition of F/C=1.57 and O/C=0.040 as measured by ESCALAB-5 was prepared. Next, the same polyimide film used in Example 1 was treated with Ar-CO ₂ (90
1000W in a mixed gas of (mol%: 10mol%)
The treatment was performed at a power density of min/m ² . The electrode surface temperature at this time was 30°C. Next, the treated surfaces of both of the obtained films were placed together, and using a roll laminator adjusted to a roll temperature of 260°C, the lamination speed was 0.5 m/min, and the linear pressure was 10
Bonded at Kg/cm. 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 the fluorine film caused netting. In addition, when using untreated polyimide film, lamination at a roll temperature of 260°C will result in a
Only an extremely weak adhesion force of less than g was obtained.

[Table] [Effects of the Invention] Since the present invention is constructed as described above, it is possible to achieve a remarkable modification effect even on resin films that are difficult to surface modify, such as heat-resistant polymers, and It has superior stability over time compared to the method of
It is possible to perform 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 drawings]

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: Polymer resin support electrode to be treated, 9: Discharge treatment section.

Claims (1)

[Claims] 1. When modifying the surface of a polymer resin film, the surface is coated with a dielectric material in a gas atmosphere of 100 to 1000 Torr containing at least 20 mol% or more of a rare gas element, and
The surface of the polymer resin film is heated to 500W by the discharge formed by the high voltage applied between the electrode cooled to 100°C and the dielectric covered electrode supporting the polymer resin film. A method for surface modification of a polymer resin film characterized by continuous treatment at a treatment intensity of min/m ² or more.