JPS62256710A - Production of silicon carbide fiber and film - Google Patents

Abstract

PURPOSE:To industrially produce the title silicon carbide fiber or film having excellent characteristics such as strength by forming a polycarbosilastyrene copolymer obtained from polysilastyrene, making the material infusible by cross-linking, and then baking the material. CONSTITUTION:Polysilastyrene is heat-treated or treated with UV rays, and the obtained polycarbosilastyrene copolymer is spun or formed into a film to obtain the title fiber or film. The formed product is irradiated by UV rays or heat-treated, and made infusible by cross-linking. The product is then baked at about 800-1,400 deg.C, and converted into silicon carbide. The generation of trouble due to contraction and fusion is reduced by this method, and high- performance silicon carbide fiber and film can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing high-strength silicon carbide fibers or films using polysilastyrene as a raw material.

[Prior art and its problems] Various methods have been proposed in the past for producing silicon carbide fibers. These methods can be broadly divided into (
It is classified into 1) chemical vapor deposition method, (2) type i fiber chemical processing method, and (3) polymer precursor method.

Among these, manufacturing methods that have already been commercialized include chemical vapor deposition and polymer precursor methods.

As a chemical vapor deposition method, for example, silicon tetrachloride is deposited on carbon fibers or tungsten fibers at a temperature of 1000 to 1200°C.

There is a method of producing it by passing three types of gases, hydrocarbon and hydrogen, to react and vapor deposition. In addition, there is a method similar to this method in which silicon carbide fibers are produced by reacting silicon produced by thermal decomposition of silicon tetrachloride with carbon fibers. However, all of these methods involve vapor deposition by causing a chemical reaction under high humidity, making operations difficult and increasing costs. Moreover, the fibers produced are thick,
Due to usage restrictions, its applications are limited.

On the other hand, the polymer precursor method is a method in which polycarbosilanes, which are organosilicon polymers, are spun, made infusible, and fired to produce silicon carbide fibers.
No. 26527, Special Publication No. 58-38534.

(See Japanese Patent Publication No. 58-38535 and Japanese Patent Publication No. 59-33681).

In this method of producing silicon carbide fibers using polycarbosilanes, the fiber diameter is 10 to 50 μm.
However, the manufacturing process is not only long and complicated, but also increases the production cost.

That is, this method uses a compound containing a Si-C bond,
S: A compound containing a -C bond and a Si-H bond.

Si-halogen bond, 5i-NILQ, Si-OR bond, 5i-OH bond, 3i-3i bond, 3i -0-
A first step of synthesizing an organosilicon polymer compound having silicon and carbon as main skeleton components by polymerizing a compound containing 8 bonds at 300 to 1200°C, and forming a low molecule from the organosilicon polymer compound. After processing to reduce the content of intermediate compounds, it is extracted with a solvent or in a vacuum or air.
50-700℃ in an atmosphere of COz gas, inert gas, etc.
A second step of obtaining a high molecular weight polymer (polycarbosilanes) by aging at a temperature of approximately ! A fourth step of heating the l fiber at a low temperature in an oxidizing atmosphere in a temperature range of 50 to 350°C for several minutes to three hours, and a low temperature heating of the tI! A fifth step of preheating the fibers at 350 to 800°C in vacuum or in an atmosphere of inert gas, CO gas, hydrogen gas, etc., and heating the preheated fibers in vacuum or in an atmosphere of inert gas, CO gas, hydrogen gas, etc. It is characterized by comprising a sixth step in which silicon carbide (SiC) is produced by high-temperature firing (800 to 1200° C.) in an atmosphere such as the above. In this way, silicon carbide fibers are produced through a number of steps.
A method of omitting the step of heat treatment at 350°C for several minutes to three hours has also been proposed (Japanese Patent Publication No. 58-38534
@).

In this case, it is necessary to sufficiently reduce the content of low molecular weight compounds in the second step of reducing the content of low molecular weight compounds from the organosilicon polymer compound, which requires a long treatment time and requires the treatment process to be strengthened accordingly. Must be.

Moreover, in the preheating of the fifth step, 350
The remaining low molecular weight compounds must be sufficiently evaporated off by heating to ~800°C. If the treatment in this step is insufficient, the subsequent high temperature firing step will result in 1! The fusion of miscellaneous substances occurs, and it can be used not only as a high-strength fiber, but also for reinforcement! It no longer functions as navy blue.

In recent years, as a new method to improve these points, polysilastyrene is used as an organosilicon polymer compound, and after spinning it, silicon carbide fibers are produced by simple means without heat treatment in an oxidizing atmosphere. A method for manufacturing Ia was proposed (Japanese Patent Application Laid-Open No. 58-215426@). This simple method is a method in which a polysilastyrene polymer is molded and then crosslinked and infusible by irradiation with an electron beam or irradiation with an electron spectrum having a wavelength shorter than that of visible light.

The major difference between the method using polysilastyrene and the method using polycarbosilane is as follows. That is, in a method using polycarbosilane as a raw material for spinning, dichlorodimedylsilane is first polymerized in a hydrocarbon solvent such as toluene or xylene in the presence of a sodium metal catalyst to synthesize dimethylpolysilane. This dimethylpolysilane cannot be melt-spun because its melting point and decomposition point are close to each other, and it is also poorly soluble in R-containing solvents, making dry spinning impossible. Therefore, this dimethylpolysilane was heat-treated (
For example, after heating in an autoclave at 400 to 500°C to convert it into a fusible polysilane, mH
A method of converting the data is adopted.

On the other hand, in a method using polysilastyrene as a raw material for spinning, dichlorodimethylsilane and dichloromethylphenylsilane are polymerized in the presence of a sodium metal catalyst in a toluene or xylene solvent to form polysilastyrene (dimethyl methyl Synthesize phenylpolysilane).

This polysilastyrene is fusible and soluble, and can be easily formed into fibers or films by melt molding or dry molding.

The latter polysilastyrene method, as mentioned above, is a method of forming fibers and films using polysilastyrene obtained by polymerizing dichlorodimethylsilane and dichloromethylphenylsilane, and this polysilastyrene has a melting point of (Softening point) of 80 to 130°C is easily synthesized, and when it is molded into, for example, fiber, it has a thickness of 10 to 30 μm.
It is possible to easily obtain polysilastyrene fibers having a diameter of However, this polysilastyrene fiber not only causes fusion but also tends to shrink when cross-linked and infusible by ultraviolet irradiation, and the amount of shrinkage is large (shrinks to 1/3 to 1/2). , it is extremely difficult to maintain the shape of the molded product (fiber 1). Therefore, in order to obtain high-strength silicon carbide fibers and films using this polysilastyrene, it is necessary to reduce the intensity of ultraviolet rays and irradiate them for a long time in a vacuum, or to irradiate them under extremely well-balanced tension. There is,
In addition, in the next firing process, the temperature range from low temperature to high temperature (1200
°C) It takes 20 to 200 hours to bake, and it is not necessarily an advantageous method from an industrial perspective.It is difficult to industrially produce high-strength silicon carbide fibers and films by directly molding polysilastyrene. It turned out to be difficult.

[Object of the Invention] The main object of the present invention is to solve the above-mentioned problems and to provide an advantageous method for industrially manufacturing silicon carbide fibers and films. The objective is to provide a method for manufacturing fibers and films that have higher performance than similar fibers and films.

[Structure of the Invention] The object of the present invention as described above is to use polysilastyrene as a raw material, convert it into a polycarbosilastyrene copolymer by heat treatment and/or ultraviolet treatment, and then mold the copolymer. This is achieved by the method of the present invention, which produces silicon carbide fibers and films by crosslinking and making them infusible by ultraviolet irradiation and/or heat treatment, and then converting them into silicon carbide by firing.

The raw material polysilastyrene used in the method of the present invention is prepared by reacting dichlorodimethylsilane and dichloromethylphenylsilane with a sodium metal catalyst in an inert solvent such as toluene or xylene at a temperature above their melting point by a known method. can be easily synthesized by
No. 500717).

The composition of the polysilastyrenes is expressed by the following formula (where R is 10 H3 or -C6), and the value of x is in the range of 0.3 to 0.7, preferably 0.4 to
0.6, particularly preferably in the range of 0.45 to 0.55, and those in which n is 5 or more, preferably 10 to 3,000 are used.

In the method of the present invention, the above-mentioned polysilastyrene is not directly molded, but is converted into a polycarbosilastyrene copolymer by heat treatment, ultraviolet treatment, or both, and then molded (spun). Or film production)! 11 or make it into a film.

In the method of the present invention, the heat treatment of polysilastyrene consists of 3
Within the range of 50 to 550°C, preferably 380 to 480°C
It is carried out within the °C range. The treatment time is selected within the range of 10 minutes to 10 hours depending on the heat treatment temperature.

For example, when processing at a temperature of 350°C, 5 to 10 hours are required, and at 550°C, less than 10 minutes is sufficient. If the treatment is carried out for more than 10 minutes at a temperature of 550°C or higher, the softening point of the resulting copolymer will become too high, and the spinning (or film forming) temperature will also exceed 30°C.
When the temperature exceeds 0° C., insoluble matter may be generated during spinning (or film forming), and spinning (or VA forming) may not be possible.

Therefore, the heat treatment temperature and time are approximately 500℃ and 3~5℃.
minutes, 8-15 minutes at 450°C.

At 400°C, about 20 to 60 minutes is sufficient. This heat treatment is suitably performed in an inert gas (for example, nitrogen gas) and then under reduced pressure.

In the present invention, the borino-j-rubosilastyrene copolymer is an organosilicon polymer suitable for melting and spinning, which is obtained by heat treatment or ultraviolet treatment of polysilastyrene as described above. When polysilastyrene is heat-treated or treated with ultraviolet light, some benzene is produced as a low-boiling substance.
At the same time, carbosilane (E-3!-
CH2+ bonds are generated and the polymer is partially cross-linked to form a polymer, the softening point increases, and the temperature for forming, such as spinning, increases. In other words, the polycarbosilastyrene referred to in the present invention is as follows (
It is an organosilicon polymer (copolymer) consisting of a carbosilane bond (I) and a silastyrene bond (■) below, and also has a partially crosslinked bond.

+CH2S! ÷...(I>The structure of this polycarbosilastyrene copolymer is identified by infrared spectrum analysis and NMR.

A typical polycarbosilastyrene copolymer has the following formula 1)
It can be expressed as

(However, R1 is a part) (3 or - days, R2, R
3 represents -CH3,H or -C6)Is, which may be the same or different. ) The average molecular weight of the above-mentioned copolymer is iooo or more, and is particularly preferably within the range of 1000 to 5ooo. In addition, the ratio of the above (I> and (II) in the copolymer is 3/7
It is preferably within the range of ~7/3.

In the method of the present invention, the polycarbosilastyrene copolymer produced as described above is melt-spun into fibers (multifilaments), and when it is irradiated with ultraviolet rays or heat-treated, the shrinkage during that treatment and subsequent steps is small. ,
In addition, there is almost no fusion between fibers, and even when immersed in tetrahydrofuran or toluene, it does not melt.
It was confirmed that the shape was completely retained.

On the other hand, fibers spun by mixing polysilastyrene and polycarbosilane in equal parts have less shrinkage even when treated with ultraviolet irradiation at room temperature, and there is less fusion of the fibers with tassels. This fiber has almost no effect on UV irradiation, and when it is immersed in tetrahydrofuran or toluene, it dissolves and completely loses its shape. Therefore, it can be seen that the above polycarbosilastyrene copolymer is not simply a mixture of polysilastyrene and polycarbosilane, but is a copolymer having carbosilane bonds and silastyrene bonds in the same molecule.

Molding of the polycarbosilastyrene copolymer in the method of the present invention can be carried out by either a melt molding method using melt extrusion or a so-called dry molding method in which it is dissolved in a solvent and then molded into an appropriate form such as a fiber or film by removing the solvent. This method is also possible.

The melt molding method is preferred from the viewpoint of economy and operability.

For example, when producing fibers by the method of the present invention, the polycarbosilastyrene copolymer may be melt-spun at a temperature range of 150 to 350°C, preferably 170 to 300°C, and a spinning speed of 200 to 1300 m/min. can. Polycarbosilastyrene copolymers suitable for spinning preferably have a spinning temperature of 150 to 350°C;
℃ or lower is not preferable because the fibers tend to shrink or fuse during ultraviolet irradiation or heat treatment in the crosslinking and infusibility step described below. Furthermore, if the spinning temperature exceeds 350°C, infusibility or gelation occurs during spinning, making spinning impossible. Therefore, the polycarbosilastyrene copolymer used in the method of the present invention has a spinning temperature of 150 to 350°C, particularly 170 to 300°C.
℃ is preferred.

In the method of the present invention, ultraviolet irradiation treatment or heat treatment is employed as a treatment for crosslinking and infusible the fiber or film formed as described above.

Ultraviolet irradiation treatment is! It is carried out at a temperature ranging from warm to 300°C or less, preferably from 10 to 100°C. At low temperatures, air may be used, but at temperatures above 80° C., it is preferable to use a reduced pressure or an inert gas atmosphere such as nitrogen gas, hydrogen gas, air, argon, or helium.

Further, the heat treatment for crosslinking and infusibleizing the fiber or film formed as described above is carried out at a temperature of 50°C to 300°C or less, preferably 70 to 200°C.

The treatment is carried out under reduced pressure or in an inert gas atmosphere such as hydrogen gas, air or nitrogen gas.

When performing heat treatment, for example, from 50℃ to 100℃1
It is sufficient to hold the temperature for 0 to 60 minutes, and in some cases, the temperature may be further increased to 200°C at a rate of about 2°C/min.
It may be held at that temperature for 10 to 60 minutes.

In addition, it goes without saying that both ultraviolet irradiation and heat treatment may be performed when making the material infusible.

Fibers and films that have been rendered infusible by ultraviolet irradiation or heat treatment are then heated at 200°C to 8°C.
After heating to 00℃ for 1 to 100℃, it is heat treated (high temperature firing) at a temperature of 800 to 1200℃ in a gas atmosphere such as nitrogen gas, argon, helium, etc., and converted into silicon carbide fiber or film mainly composed of SiC. , resulting in high performance silicon carbide fibers or films.

[Effects of the Invention] According to the method of the present invention as described above, compared to conventionally known methods, the manufacturing process is simpler, and troubles due to shrinkage and fusion are extremely small, and silicon carbide can be manufactured industrially advantageously. fibers and films can be produced. Moreover, the fibers obtained.

The film has good performance and can be widely used in various fields.

[Example] Next, the present invention will be described with reference to Examples, but the present invention is not limited thereto.

Example 1 Polysilastyrene (softening point 86-94°C) obtained by polymerizing equimolar moles of dichlorodimethylfuran and dichloromethylphenylsilane in a toluene solvent at 110°C using a Na-dispersed catalyst was heated at 400°C. The mixture was heat-treated in an inert gas (nitrogen) for 20 minutes and then treated at the same temperature under reduced pressure for 5 minutes to obtain a polycarbosilastyrene copolymer having a softening point of 190 to 200°C.

Its average molecular weight was 4500, and the ratio of carbosilane bonds to silastyrene bonds was 45/55. When this copolymer was melt-spun at a spinning temperature of 230 to 240°C, smooth spinning was possible at a spinning speed of 200 to 1000 TrL/min, and the spinnability was extremely good.

A portion of the borino J rubocila styrene comonopolymer fiber obtained by melt-spinning this copolymer at 235° C. and 600 TrLZ was heat-treated in air and the other portion under reduced pressure.

The heat treatment was performed by increasing the temperature from 50°C to 100°C at a rate of 1°C/min and holding the temperature at 100°C for 60 minutes to infusible the fibers. The resulting heat treatment! 1 fiber showed no fusion and almost no shrinkage in both cases. Furthermore, when these were immersed in tetrahydrofuran and toluene, they completely retained their shape. These heat-treated fibers were heated from 1-200°C to aOO°C at 1°C/min in an inert gas (nitrogen).

The temperature was raised from 1200°C to 1200°C at a rate of 40°C/min, and the firing was continued at 1200°C for 1 hour.

No fusion was observed in the obtained fired fibers, and as a result of X-ray analysis, it was confirmed that the fibers had been converted into silicon carbide fibers mainly made of SiC and having a β-8iC crystal factor. The characteristics of these fibers are: The fibers with a thread diameter of 8 to 10 μm and heat treated in air have a tensile strength of 310 kg/t.
mA, the tensile modulus is 18T/mai, and the strength and modulus of the fiber heat-treated under reduced pressure are 3, respectively.
To 20! F/s, 18T/-.

Example 2 A softening point of 78 to 78 was obtained in the presence of a Na-dispersed catalyst in a toluene solvent using 0.55 equivalents of dichloromethylphenylsilane to 0.45 equivalents of dimethyldichlorosilane.
Polysilastyrene at 84°C was heat-treated at 390-400°C in an inert gas for 40 minutes and then treated under reduced pressure to obtain a polycarbosilastyrene copolymer with a softening point of 180°C. This copolymer was spun at a spinning temperature of 210 to 230°C.
Melt spinning was possible at a spinning speed of 0 to 10,007 FL/min. This was spun at 220° C. at a spinning speed of 600 m 2 /min, and the II fiber was heat treated in the same manner as in Example 1 to make it infusible. This fiber was fired at an elevated temperature up to 800°C in the same manner as in Example 1, then at a rate of 500°C/hr from 800 to 1200°C, and then at 1200°C for 30 minutes to form a silicon carbide fiber. ? Ta. The diameter of this mH is 7~
8μm, tensile strength 315 to 9/mA, elastic modulus 18T/-
Met.

Example 3 The same polycarbosilastyrene copolymer as in Example 1 was melted and discharged from a slit at 230° C. and cooled on a discharge drum to form a film with a thickness of 30 microns.

This film was heat treated at 150° C. for 5 hours and then fired under the same conditions as in Example 1, and a good silicon carbide film was produced.

Comparative Example 1 Polycarbosilane having a softening point of 170 to 175°C was melt-spun at a spinning temperature of 185 to 190°C and a spinning speed of 200 to 600 m/min.

This polycarbosilane vatI41 was prepared in the same manner as in Example 1.
It was made infusible by heat treatment. This heat-treated fiber was fired in the same manner as in Example 1, and the results were as follows! ! The navy blue shrank and caused fusion, and the fiber strength was poor <1057 (9/#i).

Example 4 Polysilastyrene copolymer (softening point 81-91°C) obtained by carrying out a polymerization reaction at 110°C using equimolar amounts of dichlorodimethylsilane and dichlorodiphenylsilane and a Na-dispersed catalyst in a toluene solvent. was treated at 420°C for 30 minutes under reflux in an inert gas (nitrogen) atmosphere, followed by treatment under reduced pressure of 2-3 #W1 for 15 minutes to reach a softening point of 20.
A polycarbosilastyrene copolymer having a temperature of 0 to 210°C was obtained. The composition of this copolymer has a carbosilane bond/silastyrene bond ratio of 45/55, and an average molecular weight of 4.
It was 600.

When this copolymer was used for spinning at a spinning temperature of 220 to 230°C, melt spinning was possible at a speed of 600 to 1300 m/min, and the spinnability was extremely good.

This copolymer was spun at a spinning temperature of 240°C and a spinning speed of 600 m/
The polycarbosilastyrene copolymer fibers spun in 20 minutes were subjected to ultraviolet irradiation treatment (lamp output 100 w/cIr) for 1 hour in air at 20°C and then under reduced pressure of 1M1 (lamp output 100 w/cIr). No fusion was observed in the irradiated fibers, and almost no shrinkage was observed.

Next, this fiber was heated at 350°C in an inert gas (nitrogen) atmosphere.
for 1 hour, then from 350°C to 800°C for 20
Increase temperature at 0℃/hr, from 800℃ to 1200℃, C is 3
The temperature was increased to 00° C./hr and then fired at 1200° C. for 30 minutes. The obtained fibers showed no fusion at all,
As a result of X-ray analysis, it was found that silicon carbide [t] had a β-8iC crystal form and was mainly composed of SiC.

The characteristics of this fiber are a thread diameter of 7 to 9 μm and a tensile strength of 32O.
Ny/m, and the tensile modulus was 18T/-.

Comparison lI42 Using the polysilastyrene used in Example 1 with a softening point of 86 to 94°C, the spinning temperature was 140 to 150°C, and the spinning speed was 2.
The fibers were spun at 600 m/min to obtain polysilastyrene fibers. When this fiber was heat-treated in the same manner as in Example 1, it was found that the fiber had a slow shrinkage, fusion occurred, and the fiber had completely lost its shape.

Example 5 Polysilastyrene (softening point 86-94°C) obtained by polymerizing equimolar moles of dichlorodimethylfuran and dichloromethylphenylsilane in a toluene solvent with a Na-dispersed catalyst at 110°C was heated at 420°C. After heat treatment in an inert gas (nitrogen) atmosphere for 30 minutes at
The softening point was 200-21 after heat treatment for 15 minutes under reduced pressure.
A polycarbosilastyrene copolymer at 0°C was obtained. The average molecular weight of this copolymer is about 4500, and the carbosilane bond/
The proportion of silastyrene bonds was 45,155. This copolymer could be spun at a spinning speed of 220 to 1300'rrL/min, and its spinnability was extremely good.

Polycarbosilastyrene copolymer fibers were spun at 600 m 2 /min at a temperature of 240° C., and a portion of the fibers were subjected to ultraviolet irradiation rJ1 treatment in nitrogen gas and the other portion under reduced pressure.

Irradiation is 200 μv using two lamps with an output of 80 W/α.
The test was carried out for 1 hour at a temperature of 20° C. with an illuminance of t/ci. In both of the obtained ultraviolet (UV) irradiated 1aN, no fusion was observed and almost no shrinkage was observed. Furthermore, when these were immersed in tetrahydrofuran and toluene, they completely retained their shape.

These LIV-treated fibers were heated from 350°C to 1°C in a nitrogen atmosphere.
Firing was continued at 1200°C for 30 minutes from 200°C to 200°C.

1! ? No fusion was observed in the fired fibers, and as a result of X-ray analysis, it was confirmed that the fibers had been converted into silicon carbide tIN mainly composed of SiC and having a β-8iC crystal form. The characteristics of this fiber are that the yarn diameter is 7 to 9 μm, and the fiber that has been irradiated with UVWi under reduced pressure has a tensile strength of 31! Jff
/rutA, the tensile modulus was 18 T/-, and the strength and elastic modulus of [[[[] were 320 Kff/aj and 19 T/-, respectively.

Example 6 A softening point of 78 was obtained using 0.55 equivalents of dichloromethylphenylsilane to 0.45 equivalents of dimethyldichlorosilane in a toluene solvent in the presence of a Na-dispersed catalyst.
~84℃ polysilastyrene in an inert gas atmosphere
After heat treatment at 30°C for 20 minutes, 3 to 10. )-i under reduced pressure at the same temperature for 5 minutes to obtain a softening point of 190-210°C
A polycarbosilastyrene copolymer was obtained. The average molecular weight of this copolymer is about 4500. The ratio of carbosilane bonds to silastyrene bonds was 43/57. This copolymer was spun at a spinning temperature of 220 to 260°C and a spinning temperature of 230 to 600°C.
Melt spinning was performed at a spinning speed of TrL/min. This fiber was subjected to ultraviolet irradiation treatment in the same manner as in Example 5. This irradiated fiber was heated from 250℃ to 800℃ in nitrogen gas at 400℃/h.
Baking at elevated temperature at 800-1200℃ at 500℃/
Silicon carbide fibers were obtained by heating at 1200° C. for 30 minutes. The diameter of this fiber is 7-8
In μm, tensile strength 305Kg/-, elastic modulus 18■/-
Met.

Example 7 The polysilastyrene having a softening point of 81 to 91°C used in Example 5 was treated with ultraviolet rays at a temperature of 50°C under reduced pressure for 2 hours.

This treated polymer (polycarbosilastyrene copolymer) was prepared at a spinning temperature of 185 to 210°C and a spinning speed of 200 to 600°C.
As a result of melt spinning at m/min, the spinnability was extremely good. Next, this polycarbosilastyrene fiber was subjected to ultraviolet irradiation treatment at 60° C. for 1 hour under reduced pressure.

The morphology of the irradiated fibers was good, and the treated fibers were fired in nitrogen gas at a temperature increase of 400°C/hr from 200°C to 600°C, then fired at a rate of 500°C/hr from 600°C to 1200°C, and then fired at a rate of 500°C/hr from 600°C to 1200°C. High strength silicon carbide II was obtained by heat treatment at .degree. C. for 1 hour.

Example 8 The same polycarbosilastyrene copolymer as in Example 5 was melted and discharged through a slit and cooled on a drum to a thickness of 3.
It was made into a 0 micron film.

This film was irradiated with ultraviolet rays at room temperature under reduced pressure for 1 hour and then fired under the same conditions as in Example 5, and a good silicon carbide film was produced.

Comparative Example 3 Polycarbosilane with a softening point of 170 to 175°C was spun at a temperature of 185 to 190°C and a spinning speed of 200 to 600,771°C.
/min.

When this polycarbosilane fiber was subjected to ultraviolet irradiation treatment in the same manner as in Example 5 and immersed in tetrahydrofuran and toluene, it almost completely dissolved and lost its fiber shape. Furthermore, when this irradiation-treated fiber was fired in the same manner as in Example 5, the TA fibers contracted and fused, and the fiber shape could not be maintained.

Comparative Example 4 Using the polysilastyrene used in Example 5 with a softening point of 86 to 94°C, the spinning temperature was 140 to 150°C and the spinning speed was U.
Polysilastyrene spun at 20Q~600TrL/min!
1 fiber was obtained. When this fiber was subjected to ultraviolet irradiation treatment in the same manner as in Example 5, it showed significant shrinkage, fusion, and complete loss of fiber shape.

Comparative Example 5 Polysilastyrene with a softening point of 86 to 94°C used in Example 5 and polycarbosilane with a softening point of 110 to 175°C used in Comparative Example 3 were mixed in portions, and this mixture was spun at a spinning temperature of 170 to 175°C. When spun at a spinning speed of 200 to 5 oon/min at a temperature of 200° C., it showed very good spinnability. When this mixed fiber was treated with ultraviolet irradiation using the operating method of Example 5 and immersed in tetrahydrofuran and toluene, it was almost completely dissolved and the shape of the m-fiber disappeared.

It was confirmed that in this mixture, even the results of UV irradiation of polysilastyrene were inhibited.

Patent Applicant Teijin Co., Ltd. Procedural Amendment 1, Indication of Case Patent Application No. 186981/1986 2, Name of Invention Process for Manufacturing Silicon Carbide Fiber and Film & Person Making Amendment Relationship with Case Patent Applicant Teijin Ltd., 1-11 Hohonmachi, Higashi-ku, Osaka (300) (1) The following is amended on page 10, line 1 of the specification.

that's all

Claims (6)

[Claims] (1) After polysilastyrene is heat-treated and/or UV-treated to produce a polycarbosilastyrene copolymer, the copolymer is formed into a fiber or film, and this fiber or film is irradiated with UV-rays and/or heat-treated. silicon carbide fiber, which is characterized by being cross-linked and infusible and then fired;
Film manufacturing method. (2) Heat treatment of polysilastyrene at 350-550℃
The manufacturing method according to claim (1), which is carried out at a temperature of . (3) Ultraviolet irradiation treatment of polysilastyrene for 20 to 2
The manufacturing method according to claim 1, wherein the manufacturing method is carried out at a temperature of 00°C and an output of 5 to 1000 W/cm. (4) The manufacturing method according to claim (1), wherein fibers or films of the polycarbosilastyrene copolymer are crosslinked and infusible by UV irradiation treatment at a temperature of 300° C. or lower. (5) The manufacturing method according to claim (1), wherein the fiber or film of the polycarbosilastyrene copolymer is crosslinked and infusible by heat treatment at a temperature of 50 to 350°C. (6) The manufacturing method according to claim (1), wherein the calcination after crosslinking and infusibility is carried out at a temperature of 800 to 1400°C.