JPH03234821A - Method for producing high strength/high modulus inorganic fibers - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a material that has excellent mechanical properties, oxidation resistance, and wettability for composite materials through infusibility and sintering. This invention relates to a significantly improved method for producing carbon-based inorganic fibers.

(Conventional technology and its problems) Carbon fiber is lightweight, has high strength and high elasticity,
It is being used in a wide range of fields, including sports and leisure goods, aircraft, bicycles, and building materials.

As carbon fibers, PAN-based carbon fibers made from polyacrylonitrile and so-called pitch-based carbon fibers made from petroleum-based and coal-based pitches are known.

Pitch-based carbon fibers are generally inferior in strength to PAN-based carbon fibers, but since the raw materials are cheap, various studies have been conducted on ways to increase the strength.
No. 223316 discloses a method for effectively generating mesophase and orienting it during spinning.

However, since carbon fibers are basically crystalline fibers, they are hard, tend to fluff, and have poor wettability with a matrix when used as a composite material.

Therefore, various methods for surface treatment of carbon fibers have been proposed, and the currently known methods use materials such as polyvinyl alcohol, unsaturated polyester resins, and epoxy resins for the purpose of imparting flexibility to the fibers and suppressing the generation of fuzz. There are methods such as applying a suitable sizing agent to the surface, and dry or wet oxidation treatment of the surface for the purpose of improving adhesion to the matrix.

Among these treatments, the method of providing a surface oxidation layer in particular damages the fibers during oxidation, so that physical properties tend to deteriorate. Furthermore, carbon fibers cannot be used in an oxidizing atmosphere exceeding 500'C because they will burn.

Against this background, we are developing a new fiber that has high strength and high modulus, has good wettability and adhesion with the matrix, and is cheaper than the PAN-based carbon fiber that has been used in a wide range of fields. has been strongly requested.

Furthermore, it is strongly desired in various fields to improve the oxidation resistance of carbon fibers at higher temperatures.

As a method to meet this demand, for example, JP-A-62-2
The methods described in Japanese Patent Application Laid-open No. 09139 and Japanese Patent Application Laid-Open No. 61-215016 have been proposed.

These publications describe the synthesis of organopolyarylsilanes by mixing and heating reaction of organic solvent-soluble components in coal-based or petroleum-based pitches with polysilanes, which are then spun, made infusible,
A method for producing inorganic fibers having properties intermediate between silicon carbide fibers and carbon fibers by firing is described.

However, in the above method, pitch, which does not contain any organic solvent insoluble matter, is selected as one of the starting materials, and the reaction is carried out under conditions in which the insoluble matter is not produced at all in the production of organoboriarylsilane.

Therefore, the spinning raw material that is the resulting product does not contain any insoluble matter containing the mesophase state, which is said to be the most important component for developing the strength of carbon fibers.

Depending on the conditions, the inorganic fiber obtained by spinning, infusible, and firing the above-mentioned spinning raw material corresponds to graphite crystals of carbon (
002) Although a diffraction line is obtained, the orientation peculiar to pitch fibers is not observed, and a product with a high elastic modulus cannot be obtained. Furthermore, in the method of the above-mentioned publication, as the pitch component increases, the heat resistance in inert gas improves, but the oxidation resistance decreases.
Moreover, there is a problem that mechanical properties are significantly deteriorated.

(Means for Solving the Problems) The object of the present invention is to solve the above-mentioned problems and to provide pitch fibers which have the characteristics of high elasticity and have excellent strength, oxidation resistance, and wettability with respect to the composite matrix. The purpose of the present invention is to provide carbon-based inorganic fibers.

According to the present invention, a carbosilane bonding unit [■] and a silastyrene bonding unit [■]
■], and the ratio of the carbosilane bond unit (N to the silastyrene bond unit [■] is 7:3 to 3
: Random copolymer 100 in which a small number of silicon atoms (some of which are bonded to an aromatic ring of petroleum-based or coal-based pitch or a heat-treated product thereof via a silicon-carbon linking group) of an organosilicon polymer having 7 and ii) 5 to 50,000 parts by weight of a mesophase or a polycyclic aromatic compound consisting of both mesophase and optically isotropic phases obtained by heat treating petroleum-based or coal-based pitch at 200 to 500 °C. A first step of obtaining a silicon-containing polycyclic aromatic polymer characterized by heating reaction and/or heating melting at a temperature within a range; a first step of preparing a spinning stock solution of the silicon-containing polycyclic aromatic polymer and spinning it; 2 steps, and the third step is to infusible the spun yarn under tension or under no tension.
and a fourth step of firing the infusible spun fibers at a temperature in the range of 800 to 3000°C in vacuum or in an inert gas atmosphere. A method for producing a high strength, high modulus inorganic fiber is provided.

+CR2 S1+ (I) +S i -3ii−−−−−−−−−−−−CII
) CH3C6H5 However, R2 is a hydrogen atom or a methyl group, and R2 and R3 are a methyl group, a phenyl group, or a hydrogen atom.

First, the inorganic fiber of the present invention will be explained. In the following description, all "parts" are "parts by weight", and all percent (%) as a unit of component content is "% by weight".

The inorganic fiber of the present invention is an inorganic fiber obtained from a silicon-containing polycyclic aromatic polymer, and its constituent components include i) a radial structure derived from a polycyclic aromatic compound in a mesophase state constituting the polymer; , a carbon material exhibiting at least one type of crystalline arrangement selected from the group consisting of an onion structure, a random structure, a core axial structure, a skin-onion structure, and a mosaic structure; non-oriented crystalline carbon and/or amorphous carbon derived from a oriented polycyclic aromatic compound, and 1ii) an amorphous phase consisting essentially of Si, C and 0 and/or having a particle size of It is an aggregate consisting of crystalline ultrafine particles of 500 Å or less that are substantially made of βSfC and amorphous 5in
~60% by weight and O; 5i which is 0.5-10% by weight
- A high strength and high elastic modulus inorganic fiber characterized by being a C-0 material, St: 0.01 to 29%, C: 70 to 99.9% and 0.0.001 to 10%, Preferably S i ; 0
．． 1-25%, C; 74-99.8% and OiO,01
~8%.

Crystalline carbon, which is a component of this inorganic fiber, has a crystallite size of 500 Å or less, and is oriented in the fiber axis direction in a high-resolution electron microscope with a resolution of 1.5 people.
It is an ultrafine graphite crystal in which a fine lattice image corresponding to two (002) planes can be observed.

The crystalline carbon in the inorganic fibers can have a radial structure, an onion structure, a random structure, a co-radial structure, a skin-onion structure, a mosaic structure, a random structure including a partial radial structure, and the like. This is due to the presence of mesophase polycyclic aromatic compounds in the raw materials.

Total sum of constituent components i) and ii) in this inorganic fiber 1
The ratio of component 1ii) to 00 parts is 04015~
200 parts, and the ratio of components i) and ii) is 1
:0.02-4.

If the ratio of component 1ii) to 100 parts of the total of components i) and ii) is less than 0.015, the fiber is almost the same as pitch fiber, and no improvement in oxidation resistance or wettability can be expected. If the above ratio exceeds 200 parts, fine graphite crystals will not be effectively generated and fibers with a high elastic modulus will not be obtained.

In the inorganic fiber of the present invention, microcrystals with a small interlayer spacing and three-dimensional arrangement are effectively produced.

Furthermore, the distribution state of silicon can also be controlled by the atmosphere during firing and the size and concentration of mesophase in the raw material. For example, if the mesophase grows large,
The silicon-containing polymer is easily extruded into the fiber surface phase, resulting in a silicon-rich layer on the fiber surface after firing.

Next, the method for producing inorganic fibers of the present invention will be explained.

First step: The organosilicon polymer, which is one of the starting materials, is a polycarbosilastyrene copolymer prepared by the following general formula CI), and is prepared by the method described in Japanese Patent Publication No. 39617/1983. It can be prepared.

However, R is a hydrogen atom or a methyl group, and R2 and R3 are a methyl group, a phenyl group, or a hydrogen atom. m is a molecular weight of 1000 or more, X and y are x / y
= 3/7 to 7/3. The average molecular weight is preferably within the range of 1,500 to 50,000.

The polycyclic aromatic compound, which is another starting material, is obtained from pitch obtained by removing light fractions from fluid catalytic cracking residue oil (FCC slurry oil) of petroleum or its heat-treated oil, and from naphthacool. These are coal-based pitches such as coal tar pitch and coal tar pitch, and among these, those with high aromaticity are suitable.

The pitch preferably contains 5 to 98%, particularly 60 to 70%, of components insoluble in organic solvents such as benzene, toluene, xy12lene, and tetrahydrofuran. If the pitch containing less than 5% of the organic solvent insoluble content is used as a raw material, an inorganic fiber having excellent strength and elastic modulus cannot be obtained. Furthermore, if the pitch containing more than 98% of the organic solvent insoluble content is used as a raw material, the resulting copolymer will have a high melting point, making spinning difficult.

The weight average molecule it (Mt, +) of this pitch is 100
~3000.

The weight average molecular weight is a value determined as follows. That is, if the pitch does not contain organic solvent-insoluble matter, it is directly measured by gel permeation chromatography (GPC), and if it contains organic solvent-insoluble matter, it is hydrogenated under mild conditions to make it organic solvent-insoluble. After changing the components to organic solvent-soluble components, GPC measurement is performed. The weight average molecular weight of the polymer containing organic solvent insoluble matter is a value obtained by performing the same treatment as above.

The random copolymer is prepared by adding petroleum-based or coal-based pitch to an organosilicon polymer, and preferably reacting at 250% in an inert gas.
It is prepared by a heating reaction at a temperature of ~500°C.

The ratio of pitch used is 8 parts per 100 parts of organosilicon polymer.
It is preferable that it is 3-1900 parts.

If the proportion of the pitch component used is too small, the organosilicon component will increase, the compatibility with the mesophase polycyclic aromatic compound will deteriorate, the uniformity of the spinning dope will be impaired, and the strength and elastic modulus of the fired yarn will decrease. descend. Moreover, if the proportion is too high, the organic silicon polymer component is too small, and the wettability and oxidation resistance of the inorganic fiber prepared from the polymer of the present invention to the matrix decrease.

If the reaction temperature of the above reaction is too low, it will be difficult to form bonds between silicon atoms and aromatic carbon, and if the reaction temperature is too high, the generated random copolymer will be undesirably decomposed and its molecular weight will become high. .

As the inert gas, nitrogen, argon, etc. are preferably used.

The mesophase polycyclic aromatic compound is produced by, for example, preparing 3 4 petroleum-based or coal-based pitch in an inert gas to form a 30 to 5
It can be prepared by condensation polymerization while heating to a temperature of 00°C and removing the soft fraction produced.

Mesophase polycyclic aromatic compounds generally have a melting point of 20
The weight average molecular weight is in the range of 0 to 400''C, and the weight average molecular weight is in the range of 200 to 10,000.

Among mesophase polycyclic aromatic compounds, 20 to 10
Particularly preferred are those having an optically isotropic phase of 0% and containing 30 to 100% of insoluble matter in benzene, toluene, xylene or tetrahydrofuran in order to obtain a polymer that is an excellent raw material for inorganic fibers.

The random copolymer and the mesophase polycyclic aromatic compound are reacted and/or heated and melted at 200 to 500°C to obtain a silicon-containing polycyclic aromatic polymer.

The usage ratio of the mesophase polycyclic aromatic compound is preferably 5 to 50,000 parts per 100 parts of the random copolymer. If it is less than 5 parts, the mesophase content in the resulting polymer will be insufficient, so If the amount is more than 50,000 parts, a polymer for inorganic fibers with excellent matrix wettability and oxidation resistance cannot be obtained due to the lack of silicon component.

If the above-mentioned melt mixing temperature is lower than 200°C, unmelted parts will be generated, the system will become non-uniform, and the strength and elastic modulus of the fired yarn will be adversely affected, and if the melt mixing temperature is higher than 500°C, the condensation reaction will proceed violently. However, the resulting polymer has a high melting point, making it extremely difficult to spin the polymer.

The obtained silicon-containing polycyclic aromatic polymer has [the carbosilane bond unit (I) and the silastyrene bond unit [I]
[), and the ratio of carbosilane bonding unit (I) to silastyrene bonding unit [II] is 7:3
~3:7 organosilicon polymer units" (
A), component (B) which is a polycyclic aromatic compound unit whose skeleton component is mainly a clamp ring structure and is in a mesophase state; and component (B) whose skeleton component is mainly a clamp ring structure and which is an optically isotropic phase Component (C) is a polycyclic aromatic compound unit, and at least a part of the silicon atoms of component (A) are polycyclic aromatic compound units, and at least a part of the silicon atoms of component (A) are polycyclic aromatic compound units. bonded to carbon atoms. The weight ratio of component (A) to the sum of component (B) and component (C) is 1:0.5 to 200, and the weight ratio of component (B) to component (C) is 1:0.5 to 200. 1:0.02
It is preferable that it is 4.

If the weight ratio of component (A) to the sum of component (B) and component (C) is less than 0.5, the mesophase component in the silicon-containing polycyclic aromatic polymer will be insufficient, and The obtained inorganic fiber has low strength and elastic modulus, and if the above ratio exceeds 200, the inorganic fiber obtained from this polymer is due to the lack of organosilicon component in the silicon-containing polycyclic aromatic polymer. The oxidation resistance of the inorganic fibers decreases, and furthermore, the wettability of the fibers with the FRP matrix decreases.

Furthermore, if the weight ratio of (C) to (B) is less than 0.02, during melt spinning of the silicon-containing polycyclic aromatic polymer,
This is undesirable as spinning becomes extremely difficult due to decreased spinnability, yarn breakage due to uneven viscosity of the dope, etc. If the above ratio exceeds 4, the mesophase component in the silicon-containing polycyclic aromatic polymer is insufficient. Inorganic fibers obtained from the polymer have low strength and elastic modulus.

The silicon-containing polycyclic aromatic polymer usually contains 0.25 to 30% silicon atoms and has a weight average molecular weight of 20%.
0 to 11,000 and a melting point of 180 to 400°C.

The silicon atom content in the silicon-containing polycyclic aromatic polymer is 0.
If it is less than 25%, the amount of the amorphous phase made of Si and C10 or the βSiC ultrafine particles in the inorganic fiber obtained from the polymer is too small, so the wettability to the FRP matrix and the oxidation resistance of the fiber are significantly improved. If it exceeds 30%, high elasticity due to the orientation of ultrafine graphite crystals in the inorganic fiber and improvement in heat resistance in a non-oxidizing atmosphere cannot be achieved, and the fiber becomes no different from SiC fiber. Put it away.

7 8 The weight average molecular weight of the silicon-containing polycyclic aromatic polymer is 200
If it is lower than 11000, highly elastic inorganic fibers cannot be obtained from such polymers since they contain virtually no mesophase.
It has a high melting point, making spinning difficult.

When the melting point of the silicon-containing polycyclic aromatic polymer is lower than 180°C, it does not substantially contain mesophase, and the precursor system obtained by spinning this polymer is likely to fuse during infusibility, resulting in poor strength and A fired yarn with a high elastic modulus cannot be obtained, and if the temperature is higher than 400°C, the polymer will decompose during spinning, making spinning difficult.

Furthermore, the silicon-containing polycyclic aromatic polymer contains 10 to 98% of insoluble matter in organic solvents such as benzene, toluene, xylene, and tetrahydrofuran, and has an optical anisotropy of 5 to 97% at room temperature. It is preferable that

If the insoluble content of the silicon-containing polycyclic aromatic polymer in the organic solvent is less than 10% or the degree of optical anisotropy is less than 5%, the orientation of the mesophase in the fiber axis direction may occur when the polymer is melt-spun. Therefore, even if the obtained precursor system is made infusible and fired, only fibers with low strength and low modulus of elasticity can be obtained. If the degree of orientation is greater than 97%, there will be too much mesophase in the polymer, making it difficult to spin the polymer.

2nd step: The spinning polymer, which is a silicon-containing polycyclic aromatic polymer obtained in the 1st step, is heated and melted, and in some cases, it is filtered to remove substances that are harmful during spinning, such as microgels and impurities. This is then spun using a commonly used synthetic fiber spinning device.

The temperature of the spinning dope during spinning varies depending on the softening temperature of the raw material polymer, but a temperature in the range of 220 to 420°C is advantageous.

In the spinning device, a spinning tube is attached as necessary,
After setting the atmosphere in the spinning tube to one or more atmospheres selected from the group consisting of air, inert gas, hot air, hot inert gas, steam, and ammonia 90 gas, by increasing the winding speed. Fine diameter fibers can be obtained. The spinning speed in the melt spinning varies depending on the average molecular weight, molecular weight distribution, and molecular structure of the raw materials, but is preferably in the range of 50 to 5000 m/min.

Third step: The spun fibers obtained in the second step are made infusible under the action of tension or no tension.

A typical infusibility method is to heat spun fibers in an oxidizing atmosphere. The infusibility temperature is preferably 50 to 4
The temperature is in the range of 00°C. If the infusibility temperature is too low, the polymer constituting the spinning filament will not be fused, and if the temperature is too high, the polymer will burn.

The purpose of infusibility is to make the polymer that makes up the spun fibers into a three-dimensional structure that is insoluble and infusible, so that it does not melt during the next firing process and does not fuse with adjacent fibers. It is. Gases constituting the oxidizing atmosphere during infusibility include air, ozone, oxygen, chlorine gas, bromine gas, ammonia gas, and mixed gases thereof.

As an infusible method different from the above, spun fibers are infusible by T-ray irradiation or electron beam irradiation in an oxidizing or non-oxidizing atmosphere, under tension or no tension, while heating at a low temperature as necessary. method can also be adopted.

The purpose of irradiating with gamma rays or electron beams is to further polymerize the polymer that forms the spun fibers.
The purpose is to prevent the spun yarn from melting and losing its fiber shape.

The appropriate dose of gamma rays or electron beams is 101 to 1010 rads.

Irradiation can be carried out in a vacuum, an inert gas atmosphere, or an oxidizing gas atmosphere such as air, ozone, oxygen, chlorine gas, bromine gas, ammonia gas, and mixtures thereof.

Infusibility by irradiation can be carried out at room temperature, and if necessary, infusibility can be achieved in a shorter time by heating in the temperature range of 50 to 200°C.

If infusibility is carried out without tension, the spun fibers will shrink and take on a wavy shape, but this can sometimes be corrected in the next firing process, and tension is not necessarily required. In this case, good results can be obtained if the tension is greater than that which can at least prevent the spun fibers from shrinking and becoming wavy during infusibility.

The tension to be applied during infusibility is 1 to 500
A range of g 7 mm 2 is preferable, and even if a tension of 1 g 7 mm 2 or less is applied, it will not be possible to apply tension that will not cause the fibers to slack, and if a tension of 500 g 7 mm 2 or more is applied, the fibers may break.

Fourth step: By firing the infusible yarn obtained in the third step at a temperature in the range of 800 to 3000°C in a vacuum or inert gas atmosphere, inorganic fibers mainly composed of carbon, silicon, and oxygen are obtained. .

In the firing process, it is not necessarily necessary to apply tension, but high-temperature firing while applying tension in the range of 0.001 to 100 kg/mm2 makes it possible to obtain high-strength inorganic fibers with less bending.

In the heating process, it is estimated that mineralization becomes intense from about 700"C and mineralization is almost completed at about 800"C.Therefore, it is preferable to perform the calcination at a temperature of 800"C or higher, and from 3000"C. In order to obtain high temperatures, expensive equipment is required and there is no industrial advantage, so 800
Preferably, the firing is carried out at a temperature in the range of -3000<0>C.

(Effect) Since the silicon-containing polycyclic aromatic polymer of the present invention contains polycarbosilastyrene units in its components, it has extremely excellent compatibility with the mesophase polycyclic aromatic polymer in the same polymer. As a result, the spinnability of the polymer is very good, so inorganic fibers with excellent mechanical properties can be obtained.

The inorganic fiber of the present invention can be used even in a high-temperature oxidizing atmosphere.
Due to the presence of silicon atoms, the extraction of carbon atoms is well controlled, and the oxidative decomposition start temperature is 200 to 300° C. higher than that of ordinary pitch-based or PAN-based carbon fibers.

Furthermore, the presence of silicon atoms in the inorganic fibers of the present invention greatly improves the wettability of plastics and the like, and it is possible to provide plastic composite materials with high interlaminar shear strength and high bending strength in the 90° direction.

(Example) The present invention will be explained below with reference to Examples.

Example 1 Polysilastyrene obtained by polymerizing equimolar amounts of dichlorodimethylsilane and dichloromethylphenylsilane at 110°C for 10 hours using a sodium dispersed catalyst in a toluene solvent was depressurized at 410°C for 15 minutes. The polycarbosilastyrene having a softening point of 175-185°C was obtained by heat treatment below.

Among the petroleum fractions, high-boiling substances higher than light oil were subjected to fluid catalytic cracking and rectification at a temperature of 500'C in the presence of a silica-alumina cracking catalyst, and a residue was obtained from the bottom of the column. Hereinafter, this residue will be referred to as FCC slurry oil.

As a result of elemental analysis, this FCC slurry oil had an atomic ratio of carbon atoms to hydrogen atoms (C/H) of 0.75, and an aromatic carbon ratio of 0.55 as determined by nuclear magnetic resonance analysis.

200 g of the above FCC slurry oil was heated at 450'C7 for 0.5 hours under a nitrogen gas stream for 21.7 minutes, and after distilling off the distillate at the same temperature, the residue was filtered while hot at 200'C. The infusible portion at the same temperature was removed to obtain 5'7 g of light bone removed pitch.

This light bone removal pitch was an optically isotropic pitch containing 25% xylene insolubles.

Add 25 g of the above polycarbosilastyrene and 20 m of xylene to 57 g of this light bone-removed pitch, raise the temperature while stirring, distill off the xylene, and then react at 400°C for 6 hours.
1.0 g of random copolymer was obtained.

As a result of infrared absorption spectroscopy, this reaction product showed a decrease in 5i-H bonds 56 (IR: 2100 cm') existing in the organosilicon polymer and new 5tC
(Carbon of benzene ring) bond (IR: 1135c+c')
It was found that the organic silicon polymer was a random copolymer in which some of the silicon atoms were directly bonded to polycyclic aromatic rings. Additionally, this copolymer does not contain xylene-insoluble parts and has a weight average molecular weight of 1.
400, the melting point was 265°C, and the softening point was 310°C.

On the other hand, 180 g of the pitch from which light components had been removed was subjected to condensation polymerization at 400° C. for 8 hours under a nitrogen stream while removing light components generated by the reaction to obtain 97.2 g of heat-treated pitch.

This heat-treated pitch has a melting point of 263°C and a softening point of 308°C, and contains 77% of xylene-insoluble content and 31% of quinoline-soluble content, and has an optical anisotropy of 7.
It was 5% mesophase polycyclic aromatic compound.

90 g of this mesophase polycyclic aromatic compound and 6.4 g of the random copolymer were mixed, and the mixture was heated to 380 g under a nitrogen atmosphere.
The mixture was melted and heated at ℃ for one hour to obtain a silicon-containing polycyclic aromatic polymer in a uniform state.

This polymer had a melting point of 267°C, a softening point of 315°C, and contained 70% xylene insolubles.

The above high molecular weight material is used as the raw material for spinning, and the nozzle diameter is 0°15m.
Melt spinning was performed at 360°C using a metal nozzle of
The obtained spun yarn was oxidized and made infusible at 300° C. in air, and further fired at 1300° C. in an argon atmosphere to obtain inorganic fibers with a diameter of 8 μm.

This fiber had a tensile strength of 308 Kg/mm2, a tensile modulus of elasticity of 26 t/rMr12, and an observation of the fracture surface clearly showed that it had a radial structure.

After pulverizing the inorganic fibers, they were melted with alkali and treated with hydrochloric acid to form an aqueous solution, which was then subjected to high-frequency plasma emission spectroscopy (ICP).
), the silicon content was found to be 0.95%.

When the above fibers were heated and oxidized in air, no decrease in the above mechanical properties was observed even at 600'C.
It was confirmed that this product has superior oxidation resistance compared to commercially available carbon fibers, which are oxidized and burnt out.

7 8 In addition, a unidirectionally reinforced epoxy resin (bisphenol A type) composite material (V, i60%) using the inorganic fiber as a reinforcing material
The bending strength in the 0° and 90° directions is 208 kg, respectively.
/mm2.13.1Kg/mm2, and Oo of a unidirectionally reinforced epoxy composite material (Vy: 60%) using ordinary pitch-based carbon fiber (tensile strength 280Kg/nym", tensile modulus 54 t/mm2) , the bending strength in the 90° direction was 100 Kg/mmz, which was far superior to 3.5 Kg/mm2.

Comparative Example 1 (First Step) 200 g of the FCC slurry oil obtained in Example 1 was heated to 420° C. under a stream of nitrogen gas, and light fractions at the same temperature were distilled off to obtain 114 g of light fraction-removed pitch. The obtained pitch was dissolved in 500 d of xylene at 130 ° C., and after removing 69 g of xylene insoluble portion, 45 g of the organosilicon polymer obtained in Example 1 was added to 45 g of the xylene soluble portion in the obtained pitch, Copolymerized at 400°C for 6 hours and 32g
An organosilicon polymer-polycyclic aromatic reaction product (random copolymer) was obtained.

(Second step) 200g of the xylene soluble pitch component obtained in the first step,
Heat treatment was performed at 400° C. for 6 hours in an inert atmosphere to obtain 41 g of heat-treated pitch.

(Third step) 30 g of the copolymer obtained in the first step and 60 g of the heat-treated pitch obtained in the second step were heated and mixed at 300° C. for 2.5 hours.

The weight average molecular weight (M) of the product obtained by the above reaction was 1750, and the silicon content was 10.5%.
It was an optically anisotropic polymer with a low melting point of 198° C. and containing only 1% of the xylene insoluble component.

(Fourth Step) The polymer obtained in the third step was spun, infusible, and fired under the same conditions as in Example 1 to obtain a fired yarn. The yarn diameter, tensile strength, and tensile modulus of the obtained fibers were 17μ and 10μ, respectively.
It was 5 kg/mm2.7.1t 7mm290.

Further, the fiber cross section did not include any oriented structure.

Claims (1)

[Claims] Mainly composed of carbosilane bonding units [I] and silastyrene bonding units [II], and the ratio of carbosilane bonding units [I] to silastyrene bonding units [II] is 7:
A random copolymer in which at least a part of the silicon atoms of an organosilicon polymer having a ratio of 3 to 3:7 are bonded to an aromatic ring of petroleum-based or coal-based pitch or a heat-treated product thereof via a silicon-carbon linking group. 100 parts by weight, and ii) 5 to 50,000 parts by weight of a mesophase or a polycyclic aromatic compound consisting of both mesophase and optically isotropic phases obtained by heat treating petroleum-based or coal-based pitch at 200 to 500°C. A first step of obtaining a silicon-containing polycyclic aromatic polymer characterized by heating reaction and/or heating melting at a temperature in the range of , preparing a spinning stock solution of the silicon-containing polycyclic aromatic polymer and spinning. 2nd step, 3rd step of infusible the spun yarn under tension or under no tension;
and a fourth step of firing the infusible spun fibers at a temperature in the range of 800 to 3000°C in vacuum or in an inert gas atmosphere. A method for producing high-strength, high-modulus inorganic fibers. ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[II] However, R_1 is a hydrogen atom or a methyl group, R_2 and R
_3 is a methyl group, a phenyl group, or a hydrogen atom.