JPH11286025A - Manufacture of high rigidity film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a difficulty of stably passing a partly baked film containing a solvent through a heating furnace due to brittleness of a polymer film regarding steps of manufacturing the polymer film formed by passing the baked film via the furnace by fixing both ends of the baked film and heating it. SOLUTION: In the method for manufacturing a polymer film having Tg of 200 deg.C or higher and a tensile modulus of 300 kg/mm<2> or more comprising the steps of forming a solution of the polymer or a precursor solution of the polymer in a film-like state, fixing its both ends to a continuously feeding pin sheet or chuck to heat it at the stage of incorporating self-supporting properties therein; a part fixed to the pin sheet or the chuck is protected so as to be scarcely heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a film from a polymer solution, and more particularly to a method for producing a high-rigidity film in a case where the film has high stiffness so that the film becomes brittle.

[0002]

2. Description of the Related Art There are various methods for producing a polymer film. In the case of a thermoplastic polymer having a relatively low melting temperature, it is melted, directly formed into a film, and cooled to form a film. The production method is used, but when the non-thermoplastic or softening point is high, or the softening temperature and decomposition temperature are close, etc., the polymer is dissolved in a solvent to form a polymer solution, or the polymerization reaction is performed. A polymer solution is prepared by a method in which a solvent is used and the solution state is used as it is,
This is applied on a support, and heated and dried on the support until the self-supporting property is developed, and the film in a semi-dried state having the self-supporting property is peeled off from the support, and the film end is fixed. A method is adopted in which drying is completed by heating while being conveyed in a heating furnace, and the fixing of the ends is released to produce a film. Further, for example, when polyimide itself does not dissolve in a solvent as well, it may be dissolved in a solvent at a precursor stage, then formed into a film by the above-mentioned method in that state, and the conversion reaction may proceed simultaneously with heating.

In forming a film by such a method,
When the polymer film has high rigidity, the toughness of the film is lowered due to the high rigidity, and the film may be cracked or split during transportation in the heating furnace. In addition to rigidity, for example, unique monomer properties such as low water absorption and control of insulation properties are controlled, resulting in a complicated monomer composition and additive composition, which may result in marked brittleness, and have various favorable properties. In recent years, which are increasingly required,
It is extremely important to produce these films stably.

Conventional methods for suppressing the occurrence of cracks and tears include mixing an additive for preventing embrittlement, slowly heating and increasing the temperature, and allowing the furnace to flow without fixing the ends. And so on. However, embrittlement inhibitors are inherently impurities for polymers and can adversely affect other properties. The only way to increase the heating temperature slowly is to increase the length of the equipment or reduce the manufacturing speed, which is problematic in terms of productivity. Also, if the embrittlement exceeds a certain level, there is a limit even in this method. If the ends are not fixed, cracks and tears are reduced because there are no stress concentration points, but stress is applied in the film traveling direction for transport, and no stress is applied in the width direction because it is not fixed, so polymer chains are not applied. Anisotropy occurs in the orientation of, which is not preferable when isotropic properties are required.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to apply a high-rigidity polymer film on a support in the form of a solution, peel off the support from the support, and fix both ends of the support. In a method of producing continuously by heating in a medium, it is an object of the present invention to prevent a crack or the like of a film being produced due to brittleness due to rigidity without impairing the inherent characteristics of the polymer film.

[0006]

Means for Solving the Problems In view of the above problems, the present inventors have analyzed the brittleness development behavior of a high-rigidity polymer film produced from a solution state, and found the following common tendency. That is, at the stage of peeling off from the support by obtaining self-supporting properties from the solution state, the film still contains a considerable amount of solvent, and the film maintains sufficient flexibility due to the plasticizing effect of the solvent. As the drying progresses and the solvent evaporates, the plasticizing effect is gradually lost,
Instead, as the polymer molecular chains approach each other, the inherent cohesive force of the polymer is increased, and the manifestation of toughness can be seen. In many cases, the brittleness becomes remarkable in the middle stage of this process, that is, the stage in which the solvent plasticizing effect has begun to be lost and the aggregate state of the polymer has not reached the final state and the expression of toughness is insufficient. is there. In this state, fixing the edge of the film not only serves as a stress concentration point, but in the case of fixing by pinning, further gives a physically defective portion, which causes the film to break.

In order to solve this problem, if an attempt is made to increase the toughness of the film at this intermediate stage, various problems described in the prior art will occur. Therefore, the present inventors have found that it is possible to solve the problem by reducing the degree of heating only at the ends, and by completing the drying and firing of the film body before the plasticizing effect due to solvent volatilization is lost, leading to the present invention. .

That is, according to the present invention, Tg is 200 ° C. or higher,
A method for producing a polymer film having a tensile modulus of 300 kg / mm ² or more, wherein a solution of this polymer or a solution of a precursor of this polymer is formed into a film, and at a stage having self-supporting properties. In manufacturing a film by fixing both ends of the pin sheet to a continuously running pin sheet or chuck and heating the film, a portion fixed to the pin sheet or chuck is protected so as not to be easily heated. And a method of manufacturing a rigid film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A highly rigid film according to the present invention has a Tg of 200 ° C. or more and a tensile modulus of 300 kg.
/ mm ² or higher, which means that the present invention shows a more remarkable effect because the film has a tensile modulus of 5
This is the case where the thickness is at least 00 kg / mm ² and the thickness is at least 50 μm, or the tensile modulus of the film is at least 300 kg / mm ² and the thickness is at least 150 μm. Any composition is effective as long as it satisfies the above conditions,
In particular, it is effective for a high heat-resistant resin which has a strong cohesive force and the brittleness in the above-mentioned intermediate state is likely to cause a problem. For example, polyimides such as polyimide, polyamide imide, polyether imide, and polyester imide; heterocyclic-containing aromatic polymers such as polybenzimidazole and polyphenylene benzobisoxazole; aramids; and aromatic liquid crystal polymers.
And the like. As a method of forming these films into a film state in a solution state or a solution state of a precursor, a resin is cast on a support such as an endless belt or a drum by limiting the thickness by a die casting method or various coaters, Heat and dry on this support until it has self-supporting properties. The self-supporting film is peeled off from the support, and the film is passed through a heating furnace while transporting the film while fixing both ends in the width direction to form a final state as a film. The purpose of the present invention is to make it difficult to heat the fixed portion of the width direction end portion during transfer of this heating furnace, more precisely, the periphery including the fixed portion, but as a means for making it difficult to be partially heated. It is the simplest and most effective to physically cover only that part.
This method has a remarkable effect particularly when a heating method of a heat ray emission type such as an infrared furnace is used for heating. FIG. 1 shows an example of this case. It is preferable that the cover covers the edge as little as possible within a range that does not impair the stable transport of the film. However, even if only direct heat rays or wind is not applied, there is a considerable effect. In addition, a cooling device such as a water-cooled tube or an air-cooled tube can be attached to the cover to further enhance the effect of preventing heating. In the case of an infrared / far-infrared heating device, the degree of reflection may be increased by making the surface of a shielding plate attached as a cover a mirror surface.

[0010]

EXAMPLES Example 1 p-phenylenebis (trimellitic acid monoester anhydride) (hereinafter referred to as TMHQ) and 4,4'-diaminodiphenyl ether (hereinafter referred to as DADP)
E) and p-phenylenediamine (hereinafter referred to as PDA) were polymerized in dimethylacetamide (hereinafter referred to as DMAc) at a molar ratio of 4/1/3 to obtain a polyamic acid solution. As a specific polymerization procedure, both the diamines are dissolved in DMAc, TMHQ is added little by little, and finally TMHQ is added in an equimolar amount to the total amount of the diamine to thereby increase the viscosity to 3000 poise (measured at 23 ° C.). The polyamic acid solution having a solid content of 18.5% was obtained. During the reaction, the system was kept between 0 and 15 ° C. While the polyamic acid solution was cooled to 0 ° C., it was extruded into a curtain shape with a width of about 600 mm by a T-die, and was continuously taken up on an endless belt made of SUS so that the thickness finally became 75 μm after completion of firing. It was adjusted. Dry by hot air at 120 ° C for 12 minutes on the endless belt to give self-supporting properties, peel off from the endless belt,
120 ° C, 170 ° C, 300 ° C, 380 ° C, 430 in a far-infrared furnace while fixing and transporting both ends of the film with pin sheets
After heating for about 5 minutes each at ℃, the film was removed from the pin sheet to obtain a polyimide film. At this time, the upper portion of the pin sheet was shielded by a SUS plate so that the heat rays did not directly hit the pinning portion. (See FIG. 1) The obtained film had a Tg of 400 ° C. or higher and a tensile modulus of 800 kg / mm ² . In addition, 120 ° C1
The volatile content of the self-supporting film subjected to hot-air drying for 2 minutes was about 90%. (Comparative Example 1) The same steps as in Example 1 were performed, except that the same polyamic acid solution as in Example 1 was used and the upper portion of the pin sheet was not shielded by a SUS plate. As a result, a break occurred from the pinning portion during the process, and a film could not be obtained.

[0011]

As described above, the brittleness becomes remarkable in order to satisfy the high rigidity or other properties, and a film having a structure or a structure which could not be conventionally produced as a film can be stably produced. Thus, a film having a new property balance can be industrially provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of a state in which a cover for making a non-heating end of a film is attached, viewed horizontally from a film transport direction.

[Explanation of symbols]

 1 Infrared heater 2 End non-heating cover 3 pin sheet 4 pin film

Claims (5)

[Claims] 1. Tg of 200 ° C. or higher and tensile modulus of 30
A method of manufacturing a polymer film is 0 kg / mm ² or more, the solution of the solution or the polymer of the precursor of the polymer was molded into a film, and of this at the stage having a self-supporting ends Manufacturing of high-rigidity film characterized by protecting the part fixed to the pin sheet or chuck so that it is not easily heated when manufacturing the film by fixing it to the continuously running pin sheet or chuck. Method. 2. A method for making it difficult to heat only a portion fixed to a pin sheet or a chuck, wherein a cover is attached to the pin sheet or the chuck so that hot wire or hot air does not directly hit the pin sheet or the chuck. A method for producing the high-rigidity film according to the above. 3. The method according to claim 1, wherein an infrared or far-infrared heater is used as a part or all of the heating means. 4. The film has a tensile modulus of 500 kg / mm ² or more and a thickness of 50 μm or more, or the film has a tensile modulus of 300 kg / mm ² or more and a thickness of 150 μm
4. The method for producing a high-rigidity film according to claim 1, which is one of the above. 5. The method according to claim 1, wherein the film is a polyimide.