JPH054961B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a film made of a heterocyclic aromatic polymer, and more particularly to an isotropic film with excellent mechanical performance at high temperatures and a method for producing the same. (Prior art and its problems) With the development of electronics and other technologies, there is a strong demand for flexible films that have both excellent heat resistance and mechanical properties. Aramid, aromatic polyimide, aromatic polyetherketone, and the like are known as heat-resistant organic polymers, and films of these materials are being manufactured or prototyped. However, it is still insufficient in terms of heat resistance (aramid, aromatic polyether ketone), has a relatively high moisture absorption rate, and is unsatisfactory in terms of electrical insulation and moisture absorption dimensional stability (aramid).
Each has drawbacks, such as the complicated molding process (aromatic polyimide). (Object of the Invention) In view of these drawbacks of the prior art, an object of the present invention is to provide an isotropic film having both excellent heat resistance and mechanical properties, and a method for producing the same. The present inventors focused on the fact that polyparaphenylenebenzobisthiazole (hereinafter abbreviated as PPBT) has the highest heat resistance stability among organic polymers, and conducted research into making a film from it.
However, since PPBT is an extremely rigid polymer, it tends to form liquid crystals in solutions such as polyphosphoric acid and methanesulfonic acid, and the polymer concentration is 1.
It has been extremely difficult to obtain an isotropic film because it exhibits flow birefringence even when the weight percentage is extremely small. However, the inventors discovered the unexpected fact that an isotropic film can be obtained by heating these dopes statically before solidifying them, and after further research, they arrived at the present invention. That is, an object of the present invention is to obtain an isotropic organic film that has excellent heat resistance and excellent mechanical performance. (Summary of the Invention) The present invention comprises essentially the following repeating units, (Here, Ar is

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[Formula] and a copolymer selected from the group consisting of halogen, alkyl, cyano, nitro, and alkoxy nuclear substituted products thereof, and may also be a copolymer consisting of two or more Ar. A film characterized in that the ratio of the initial modulus in two mutually orthogonal directions selected is within the range of 0.5 to 2.0, and such a film is characterized in that the repeating unit,
It can be produced by casting an optically anisotropic dope or a fluid birefringent dope of a polymer consisting of the above on a planar body, heating it, and then solidifying it. The polymer forming the film of the present invention has substantially the following repeating units. Here, Ar is

【formula】

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[Formula] and their halogen, alkyl, cyano, nitro, and alkoxy nuclear substituted products. Such polymers are known per se and are polymerized in known ways. For example, 2,5-diamine-1,4 benzenedithiol 2 in polyphosphoric acid
hydrochloride

It can be obtained by dissolving [Formula], heating in an inert atmosphere to remove HCl, and then adding approximately equimolar amount of aromatic dicarboxylic acid and stirring with heating. In this case, two or more types of aromatic dicarboxylic acids may be used to form a copolymer. The film of the present invention preferably has an intrinsic viscosity of 5 or more, particularly 8 or more, as measured in methanesulfonic acid at a temperature of 30°C, since good mechanical properties cannot be obtained if the polymer has a low degree of polymerization. is preferred. The film of the present invention is isotropic, and therefore the ratio of the initial moduli in two arbitrarily selected orthogonal directions is within the range of 0.5 to 2.0. More preferably
It is within the range of 0.75 to 1.5. Such an isotropic film cannot be obtained simply by extruding the polymer dope of the present invention, but can only be obtained by a special method described below. A film in which the ratio of the initial modulus in two directions is outside the range of 0.5 to 2.0 means that the PPBT polymer is oriented in a particular direction, and the film is easily torn and its practical value is significantly reduced. The film of the invention is preferably transparent. This is because the more transparent the film is, the less uneven the agglomerated structure is, and the mechanical properties such as strength are also better. The film of the present invention preferably has a strength of 5 Kg/mm ² or more and an initial modulus of 100 Kg/mm ² or more. It also has excellent heat resistance, with a decomposition temperature of up to 600°C (in air) measured by thermogravimetric analysis. Next, a method for manufacturing the film of the present invention will be described. In producing a film, it is first necessary to create an optically anisotropic dope or a fluid birefringent dope from the polymer produced by the method described above. When a dope without optical anisotropy or flow birefringence is formed, the mechanical properties of the film often reach an insufficient level. In order to impart optical anisotropy or flow birefringence to the PPBT dope, the polymer concentration, degree of polymerization of PPBT, temperature, type of solvent, etc. are appropriately selected. Among them, the contribution of polymer concentration is very large, and in the case of PPBT, which is a very rigid polymer, it exhibits flow birefringence at approximately 1% by weight or more (i.e., it is optically isotropic at rest, but under shear deformation). It exhibits optical anisotropy at about 6 to 9% by weight or more (meaning it exhibits optical anisotropy even under static conditions). Therefore, the polymer concentration in the dope used in the production method of the present invention is preferably about 1% by weight or more, more preferably about 6% by weight or more. Examples of the solvent in this case include polyphosphoric acid, methanesulfonic acid, chlorosulfuric acid, 98% by weight or more of sulfuric acid, and fluorosulfuric acid. Two or more of these may be used as a mixture. The sulfuric acid may have a concentration of 100% or more, ie, fuming sulfuric acid. Also, hydrofluoric acid, halogenated alkyl sulfonic acid, halogenated aromatic sulfonic acid, trihalogenated acetic acid,
A small amount of phosphorus pentoxide or the like may be mixed with the above solvent. Among these, especially in the case of polyphosphoric acid, it is possible to use the liquid produced by the polymerization reaction as it is, or after concentrating or diluting it, as a so-called direct dope. Whether the dope has optical anisotropy is
“T” test, “DDA” test, observation between polarization elements,
At least one method selected from stirring and scattering light etc.
22nd line to the last line), and whether or not it has flow birefringence can be determined by whether or not it has optical anisotropy when shearing deformation is applied. For convenience, if metallic luster is observed when the dope is stirred, the sufficient condition for optical anisotropy or flow birefringence is satisfied (although this is not a necessary condition). The dope of the present invention contains conventional additives, such as fillers, anti-glare agents, UV stabilizers, heat stabilizers,
Antioxidants, pigments, solubilizing agents, etc. may be mixed. As mentioned above, the dope used in the present invention has optical anisotropy or flow birefringence at room temperature (approximately 20 to 30 degrees Celsius), but this is usually done as necessary during film molding. After undergoing operations such as degassing, filtration, and weighing, it is necessary to cast the dope onto a planar body before solidifying it, and to heat the dope at the same time. Although it is not known exactly how the dope is affected by heating the dope just before solidification, it is likely that the optically isotropic phase in the dope will increase, the boundaries of liquid crystal domains will become unclear, and monodomains will be formed. It is presumed that there is a function such as oxidation. The film forming method itself in the method of the present invention does not require the use of any special method; for example, a method in which the film is uniformly cast onto a glass plate or a metal plate and formed in a coagulation bath, or a method in which the film is formed entirely or in majority in a coagulation bath. A method using a rotating drum immersed in a coagulating bath, or a method in which a Teflon sheet or metal sheet is rotated in the form of a belt and a part of it is immersed in a coagulation bath can be used. However, heating the dope cast onto these planar bodies
This is essential for obtaining a film with isotropic and uniform mechanical properties such as initial modulus. The heating temperature varies depending on the conditions of the dope used, but is preferably at least about 80°C, more preferably about 80°C.
The temperature is 100°C or higher, most preferably about 120°C or higher.
The upper limit is determined based on the decomposability and operability of PPBT, and is, for example, about 250°C. The heating method is not particularly limited, and for example, a method of electrically or steam heating a dope transfer curved pipe, high-frequency dielectric heating of the dope flow coming out of a die or dope on a planar body, or irradiation of infrared rays. A method of blowing hot air or a method of heating a planar body and then transferring heat may be used, or a combination of these methods may be used. The heating time is
Approximately 0.1 considering operability and polymer degradability
The time is preferably at least 1 second and at most 15 minutes. The atmosphere during heating is usually air, but it may be dehumidified to prevent the dope from partially solidifying during casting or heating, or it may be an inert atmosphere such as nitrogen or argon to suppress the decomposition of the polymer. is also one of the preferred embodiments. Things that can be used as the coagulating liquid for the dope used in the present invention include water, an aqueous solution of about 50% by weight or less of an acid solvent (i.e., polyphosphoric acid, methanesulfonic acid, etc. used for dope preparation), methanol, ethanol, ethylene glycol, about 50% by weight or less. Examples include a 30% by weight or less caustic soda aqueous solution. The temperature of the coagulation bath is not particularly limited, and is usually in the range of about 5 to 80°C. The production speed of the film of the present invention during continuous production is not particularly limited, but is usually 1 to 1.
Selected between 150m/min. Since the coagulated film as it is contains acid, it is necessary to completely remove the acid content in order to produce a film with excellent mechanical properties. Water is usually used as the cleaning liquid, but if necessary, it is also possible to use warm water, or to neutralize and clean with an alkaline aqueous solution and then wash with water. Further, the cleaning method may be to run the film in a cleaning liquid or to spray the cleaning liquid. The film from which the solvent has been removed must be dried. Here, drying refers to the operation of removing cleaning liquid etc. adhering to the film, and any method may be used as long as the cleaning liquid etc. is removed, such as air drying at room temperature, heated inert gas, such as air, nitrogen, argon. Drying may be performed in an atmosphere such as in a vacuum cleaner or on a heating roll. The drying temperature is not particularly limited, but considering the drying ability and decomposability of the polymer, it should be approximately 700℃ above room temperature.
℃ or less is preferably used, but in the special case of producing a film with little heat shrinkage, a temperature of about 100°C or more and about 700°C or less is preferably used. Further, during drying, if excessive tension is applied only in either the width direction or the winding direction, the film will become directional, which is undesirable, and drying is usually carried out under no tension or isotropic tension. In this way, the film formed by the method of the present invention can be washed as-formed, that is, solidified, simply washed with water, and dried (without tension or under slight tension).
It has excellent mechanical properties even without stretching heat treatment. However, depending on the purpose, 2
It is also possible to stretch the shaft to impart even better mechanical properties. In producing a film by the method of the present invention,
The above steps may be either batchwise or continuous, and one preferred embodiment is to manufacture while running the film continuously throughout the entire process. Further, an oil agent, an identification dye, or the like may be applied to the film at an arbitrary step. (Effects of the Invention) The first effect of the present invention is that, for the first time, it was possible to successfully obtain a film with isotropic properties from PPBT, which has the highest heat resistance among organic polymers. The film of the present invention has a substantially isotropic initial modulus and also has no anisotropy in strength and elongation. Therefore, it does not tend to tear in any particular direction. Further, the film of the present invention has good mechanical properties even without a stretching step after forming, and has a strength of 5 Kg/mm ² or more and an initial modulus of 100 Kg/mm ² or more. In addition, it is flame retardant and has good chemical resistance. The film of the present invention is useful as an electrical insulating material, a wire covering material, an electronic circuit board, a magnetic memory material support, a filtration membrane, a packaging material, etc. by making use of the above-mentioned properties. (Examples of the invention) Examples of the invention are shown below, but these are not intended to limit the invention. In addition, parts or % in Examples indicate parts by weight or % by weight unless otherwise specified. In addition, the strength and elongation and Young's modulus were measured using a constant speed extension type strength and elongation measuring device.
Cut into a rectangle of mm x 20 mm and measure the initial grip length.
A load-elongation curve was drawn at 50 mm and a tensile speed of 25 mm/min, and the calculation was made from this. Example 1 Wolfe et al. (Macromolecules, Vol. 14, No.
PPBT was obtained by the method described in (1981), p. 915. That is, 38.7 g of 2,5-diamino-1,4-benzenethiol dichloride was weighed out in a nitrogen box, and added to a cylindrical separable flask equipped with a stirring blade containing 209 g of sufficiently degassed polyphosphoric acid. After stirring at room temperature under a nitrogen atmosphere for about 24 hours, the temperature was raised to 65°C and stirring was continued for about 30 hours to completely remove hydrogen chloride. Next, 26.2g of terephthalic acid was added and 287g of degassed polyphosphoric acid was added.
and stirred at 110℃ for about 5 hours, then heated to 165℃
The temperature was raised to 165°C and stirred for 12 hours, then the temperature was raised to 180°C and stirred at 180°C for 12 hours, and finally the temperature was raised to 190°C and stirred at 190°C for 5 hours to complete the polymerization reaction. I let it happen.
A portion of the obtained PPBT polymer was isolated and the intrinsic viscosity measured in methanesulfonic acid at 25°C was 8.2. At the end of the polymerization, the polyphosphoric acid contained 8% by weight of the polymer and exhibited optical anisotropy in the range from room temperature to about 200°C. A portion of this dope was diluted with polyphosphoric acid to prepare a 2.0% by weight dope. This dope exhibited birefringence under shear stress. The diluted dope was cast onto a glass plate in an oven kept at 90° C. using applicators with 0.25 mm spacing. After standing in air at 90°C for about 3 minutes, it was placed in water at room temperature to solidify. After washing with water overnight, dry it in an oven at 80℃ for a fixed length of about
A film with a thickness of 15 μm was obtained. This film is
It is transparent, and the strength in the direction in which the applicator is drawn, in the direction perpendicular to it, and in the direction 45 degrees to it is 9.6Kg/9.6Kg/
mm ² , 8.9Kg/mm ² , and 9.0Kg/mm ² , and the initial moduli are 370Kg/mm ² , 280Kg/mm ² , and 330Kg/mm ² , respectively.
It was hot. In addition, this film can be heated from room temperature to 250℃.
No dimensional change was observed even when the temperature was increased to . Also,
It was found to have good electrical insulation properties, exhibiting an electrical conductivity of less than 10 ^-10 Ω ^-1 cm ^-1 . Example 2 Using the same method as in Example 1, the as-polymerized dope was used to form a film at about 180°C. In this case, a stainless steel plate with a mirror finish is heated to 180°C.
A dope preheated to approximately 150°C was cast onto the dope in a nitrogen atmosphere, and heated for approximately 10 minutes. Then, a 10% phosphoric acid aqueous solution at 50°C was used as the coagulation liquid. and solidified. The film obtained by washing with water and drying as in the case of diluted dope has a diameter of 48 μm.
It had a thickness of . When the strength was measured in the same way as the film obtained from diluted dope, it was 12.1Kg/mm ² , 9.3
Kg/mm ² , 9.9Kg/mm ² , and the initial modulus is
They were 490Kg/mm ² , 320Kg/mm ² , and 290Kg/mm ² . Example 3 In the same manner as in Example 1, PPBT with an intrinsic viscosity of 15.3 was prepared.
This was redissolved in methanesulfonic acid at room temperature to 50°C to prepare a 12% by weight optically anisotropic dope. After degassing, pump the liquid with a metering gear pump to approximately 200
The dope stream was discharged into space from a die heated to ℃ and cast onto a stainless steel belt moving at approximately 5 m/min while heating the dope stream with an infrared lamp. The stainless steel belt that holds the dope is structured so that it enters a heating chamber in which a nitrogen stream of approximately 200 to 210°C circulates, allowing it to be heated to approximately 200°C from both the top and bottom. After the dope remained in this heating chamber for about 7 minutes, it was immersed together with the belt in a coagulation bath consisting of a 10% methanesulfonic acid aqueous solution, and then peeled off from the belt. The taken out film was washed with a 0.3% caustic soda aqueous solution, then water, and dried at 150°C for a fixed length. As a result, a transparent and tough film was obtained, whose strength and initial modulus in the direction of winding were 16±4Kg/mm 2 and 350±70Kg/mm 2 , respectively, and the strength and initial modulus in the direction perpendicular to the direction of winding were 16±4Kg/mm ² and 350±70Kg/mm ² , respectively. , 11±2
Kg/mm ² , 260±30Kg/mm ² . Note that these data show the average value and existence range of the measured values when η=7.

Claims (1)

[Claims] 1. A polymer having substantially the following repeating units: (Here, Ar is selected from the group consisting of [formula] [formula] [formula] [formula] [formula] [formula] [formula] and their halogen, alkyl, cyano, nitro, and alkoxy nuclear substituted products, and 2 A heterocyclic film whose main component is a copolymer containing more than one species of Ar), characterized in that the ratio of the initial modulus in two arbitrarily selected mutually orthogonal directions is within the range of 0.5 to 2.0. A film made of aromatic polymer. 2. The film according to claim 1, comprising a polymer having an intrinsic viscosity of 5 or more when measured in methanesulfonic acid at a temperature of 30°C. 3 Polymers having substantially the following repeating units: (Here, Ar is selected from the group consisting of [formula] [formula] [formula] [formula] [formula] [formula] [formula] and their halogen, alkyl, cyano, nitro, and alkoxy nuclear substituted products, and 2 A heterocyclic aromatic polymer characterized by casting an optically anisotropic dope or a fluid birefringent dope (which may be a copolymer containing more than one species of Ar) onto a planar body, heating it, and solidifying it. How to make a film.