JPH02274732A - Silicon-containing polycyclic aromatic polymer and its production - Google Patents

Abstract

PURPOSE:To obtain the subject polymer which can give a high-strength and high-elasticity carbonaceous inorganic fiber by heat-treating a specified organosilicon polymer/polycyclic aromatic compound random copolymer and a premesophase polycyclic aromatic compound. CONSTITUTION:An organosilicon polymer having a ratio of the total number of the combined units Si-CH2 to the total number of the bonding units Si-Si in the range of 1:(0-20) and having a substituent such as H, a lower alkyl, a phenyl or a silyl as a side chain of the silicon atom is prepared. The carbon atoms of the aromatic ring of a polycyclic aromatic compound are bonded to the silicon atoms of this polymer to produce a random copolymer. 100 pts.wt. this random copolymer and 5 to 900 pts.wt. premesophase polycyclic aromatic compound obtained by hydrogenating a petroleum- or coal-derived pitch and heat-treating the product in a vacuum are subjected to heat reaction and/or heat melting at 200 to 500 deg.C to obtain a silicon-containing polycyclic aromatic polymer.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides an inorganic fiber with excellent mechanical properties, oxidation resistance, and compatibility with a matrix for composite materials;
The present invention relates to a precursor polymer suitable for producing matrices for composite materials, molded articles, etc. with excellent oxidation resistance, abrasion resistance, heat resistance, etc., and a method for producing the same.

(Conventional technology and its problems) Carbon fiber is lightweight, has high strength and high elasticity,
It is 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 fiber cannot be used in an oxidizing atmosphere at a temperature exceeding 500°C because it 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.

On the other hand, so-called C/C composites and carbon molded bodies that use carbon fiber as the reinforcing fiber and carbon as the inorganic matrix have excellent specific strength, specific elasticity, heat resistance in a non-oxidizing atmosphere, toughness, and friction properties, and are heat resistant. It is promising as a structural material and brake material.

However, since the matrix of C/C composites and carbon molded bodies consists only of carbon, it is difficult to use them for long periods in an oxidizing atmosphere, and although they have excellent friction properties and lubricity, Abrasion resistance is not necessarily sufficient, and improvement in the mechanical properties of the layer is expected.

As a method for solving the problems with the fibers, for example, JP-A-62-209139, JP-A-61-21,
No. 5016 discloses that organopolyarylsilane is synthesized by mixing and heating an organic solvent-soluble component in coal-based or petroleum-based pitch and polysilane, and then it is spun, infusible, and fired to form silicon carbide fibers and carbon. A method for producing inorganic fibers with properties intermediate to that of fibers 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 organopolyarylsilane.

That is, the spinning raw material that is the obtained product does not contain an oriented component that is essential for developing the strength of carbon fibers, and high elasticity inorganic fibers are not obtained from the spinning raw material.

Furthermore, the method disclosed in the above-mentioned publication has the problem that as the pitch component increases, the heat resistance in an inert gas improves, but the oxidation resistance decreases, and furthermore, the mechanical properties deteriorate significantly.

In addition, as a method of compensating for the essential drawbacks of the carbon matrix, Am, Ceram, Soc, Bull, 6
2 (1983) 916, Walker (B.E.
Walker, Jr.) have described a method in which a C/C composite is impregnated with an organosilicon polymer and then thermally decomposed to introduce silicon carbide components into the matrix. The strength is low at 158MP.

Also, Proc, of Int, Symp, on C
eramic, Compon.

for Engine, 1983. Japan, p50
In 5, Fitzer et al. describe a method in which a C/C composite is impregnated with a silicon melt to convert the matrix into silicon carbide, but the resulting composite material is Since metallic silicon remains unreacted between the matrix particles, creep metamorphosis occurs at high temperatures of 1300° C. or higher, and the C/C composite does not have the high-temperature properties that C/C composites have.

In addition to the conventional complicated C/C composite manufacturing process, each of the above-mentioned processes involves an additional complicated process, making it difficult to use industrially.

Therefore, there is a strong demand for the development of precursor polymers that can be easily converted into excellent carbonaceous inorganic fibers, matrices for composite materials, etc. by mineralization.

(Means for Solving the Problems) An object of the present invention is to provide inorganic fibers with excellent mechanical properties, oxidation resistance, and compatibility with matrix for composite materials; It is an object of the present invention to provide a precursor polymer which solves the above-mentioned problems and is suitable for the production of matrixes for composite materials, molded articles, etc., which have excellent heat resistance, etc., and a method for producing the same.

According to the present invention, (A) mainly consists of a bonding unit (S i -CHz), or a bonding unit (Si CHz) and a bonding unit (Si-Si), and has a hydrogen atom, a lower alkyl group, An organosilicon polymer unit having a substituent selected from the group consisting of a phenyl group and a silyl group, and (B) a polycyclic aromatic compound unit mainly in a pre-mesophase state, wherein at least one of the silicon atoms of (A) is Some of the
There is provided a silicon-containing polycyclic aromatic polymer characterized in that the silicon-containing polycyclic aromatic polymer is bonded to the carbon atom of the aromatic ring of (B).

Further according to the invention, i) the bonding unit (Si CH2) or the bonding unit (S
The bonding unit (S i -CH2) total number of pairs of bonding units (
The aroma of a polycyclic aromatic compound in which at least a part of the silicon atoms of an organosilicon polymer having a total ratio of Si-Si) in the range of 2 to 20 is petroleum-based or coal-based pitch or a heat-treated product thereof. 100 parts by weight of a random copolymer bonded to the carbon of the group ring, and ii) a polycyclic aromatic compound mainly in a pre-mesophase state obtained by hydrogenating petroleum-based or coal-based pitch and then heat-treating it under reduced pressure. Provided is a method for producing a silicon-containing polycyclic aromatic polymer, characterized in that 900 parts by weight of the silicon-containing polycyclic aromatic polymer is subjected to a heating reaction and/or a heating melting at a temperature in the range of 200 to 500°C.

First, the silicon-containing polycyclic aromatic polymer of the present invention will be explained. In the following description, all "parts" are "parts by weight" and are percentages (%) as a unit of component content.
are all "% by weight".

The silicon-containing polycyclic aromatic polymer of the present invention comprises the constituent component (A
), (B), and at least a part of the silicon atoms of component (A) are bonded to the carbon atoms of the aromatic ring of component (B). It is preferable that the weight ratio of component (A) to component (B) is 1:0.5 to 200.

The weight ratio of component (A) and component (B) is 0.5
If it is less than this, the silicon-containing polycyclic aromatic polymer will lack the primesophase component, and for example, even if inorganic fibers are produced from this polymer, only those with low strength and elastic modulus will be obtained. In addition, if the above ratio exceeds 200, the oxidation resistance of the inorganic compounds in the silicon-containing polycyclic aromatic polymer decreases due to the lack of organosilicon components in the silicon-containing polycyclic aromatic polymer. sex becomes lower.

The silicon-containing polycyclic aromatic polymer of the present invention has 0 silicon atoms.
．． Contains 25-30% and has a weight average molecular weight of 200
~11,000 and a melting point of 180-350°C.

The silicon atom content in the silicon-containing polycyclic aromatic polymer is 0.
If it is less than 25%, Si, C in the mineralized product of the polymer
,O,,Il: Because the amount of the amorphous phase or β-SiC ultrafine particles is too small, for example, the wettability and oxidation resistance to the FRP matrix do not improve significantly, and if it exceeds 30%. However, it is not possible to achieve high elasticity and improved heat resistance in a non-oxidizing atmosphere due to the orientation of ultrafine graphite crystals in the above-mentioned inorganic compound.

The weight average molecular weight of the silicon-containing polycyclic aromatic polymer is 200
If it is lower than 11,000, it contains almost no pre-mesophase and cannot provide high-performance inorganic fibers, composite materials, or molded objects. Become.

When the melting point of the silicon-containing polycyclic aromatic polymer is lower than 180'C, it does not substantially contain primesophase, and when this polymer is spun to produce inorganic fibers,
Precursor yarns tend to fuse together during infusibility, making it impossible to obtain fired yarns with high strength and elastic modulus. On the other hand, if the melting point of the polymer is higher than 350'C, the softening/flowing temperature will be high and the polymer will decompose, which is undesirable.

Further, the silicon-containing polycyclic aromatic polymer preferably contains 10 to 90% of insoluble matter in organic solvents such as benzene, toluene, xylene, and tetrahydrofuran.

If the insoluble content of the silicon-containing polycyclic aromatic polymer in the organic solvent is less than 10%, even if the polymer is melt-molded and mineralized, the carbon microcrystals will hardly be oriented in the fiber axis direction, resulting in poor mechanical properties. Inorganic fibers, molded articles, composite materials, etc. with excellent quality cannot be obtained. In addition, the insoluble matter in the above organic solvent was reduced to 9
If the content is more than 0%, the polymer will have a high melting point and high softening point, making spinning, molding, etc. of the polymer difficult.

Since the silicon-containing polycyclic aromatic polymer of the present invention softens and flows at relatively low temperatures, it is suitably used, for example, as a precursor for inorganic fibers.

Next, a method for producing the silicon-containing polycyclic aromatic polymer of the present invention will be explained.

The organosilicon polymer, which is one of the starting materials, can be synthesized by a known method. For example, polydimethylsilane obtained by the reaction of dimethyldichlorosilane and sodium metal is heated to 400°C or higher in an inert gas. It can be obtained by

The organosilicon polymer has a bonding unit (Si CH2),
Or bonding unit (Si-Si) and bonding unit (34GHz
), and the ratio of the total number of bonding units (Si CH2) to the total number of bonding units (Si-Si) is 1:0 ~
It is within the range of 20.

The weight average molecular weight of the organosilicon polymer is -300 for boat fishing.
-1000, particularly 400-800, is preferable for preparing random copolymer (1), which is an intermediate raw material for obtaining excellent inorganic fibers, composite materials, molded articles, etc.

Pitch, which is another starting material, includes pitch obtained by removing light fractions from fluid catalytic cracking residue oil (FCC slurry oil) of petroleum products or heat-treated oil thereof, pitch obtained from naphtha cool, and pitch obtained from coal. These are coal-based pitches such as tar pitch, and among these, those with high aromaticity are suitable.

The random copolymer (1) is prepared by adding petroleum-based or coal-based pitch to an organosilicon polymer and subjecting the mixture to a heating reaction in an inert gas, preferably at a temperature of 250 to 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, resulting in polycyclic aromatic compounds mainly in the pre-mesophase state (hereinafter simply referred to as "polycyclic aromatic compounds (2)"). be.

), the uniformity during melting is impaired, and when producing fibers and molded objects, the elastic modulus decreases.

Furthermore, if the proportion is too high, the organosilicon polymer component will be too small, and the compatibility with the matrix and oxidation resistance of the composite material produced from the polymer of the present invention will 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 (1) will be severely decomposed and its molecular weight will increase. This is not a good thing to happen.

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

Polycyclic aromatic compounds that are mainly in the pre-mesophase state (hereinafter sometimes simply referred to as "polycyclic aromatic compounds (2)") can be produced by, for example, treating petroleum-based or coal-based pitch with tetrahydroquinoline. , or a first stage treatment in which a part of the condensed aromatic rings in the pitch is hydrogenated by hydrogenation treatment under hydrogen pressure after adding a catalyst if necessary, and the hydrogenated pitch obtained in the first stage treatment. can be prepared by a second step of heating for a short time at high temperature under reduced pressure.

In the first stage treatment, for example, when hydrogenation is performed using tetrahydroquinoline, 30 parts or more of tetrahydroquinoline is added to 100 parts by weight of pitch, and 300"C
Hydrogenation can be carried out by heating to ~500°C. In addition, when hydrogenating with hydrogen, add a solvent such as quinoline, a cobalt-molybdenum type catalyst, an iron oxide type catalyst, etc. to the raw material pitch as necessary, and under pressure of hydrogen partial pressure 10 kg/c + ft or more, 400 ° C. Hydrogenation can be carried out at 500°C. The product thus obtained is subjected to a second stage treatment, if necessary, by filtration and removal of the solvent and light components.

The second stage treatment is a high-temperature heat treatment under reduced pressure, preferably at a pressure of 50 mmHg or less and a temperature of 440°C or more.
The heat treatment takes less than a minute. Although the treatment time is determined by the treatment temperature, it is preferable to conduct the treatment at the highest possible temperature for a short time.In particular, it is preferable to treat the silicon-containing polycyclic aromatic polymer with excellent spinnability within 15 minutes. It is suitable for producing polycyclic aromatic compound (2) to obtain.

The pre-mesophase state herein refers to a state that is optically isotropic at room temperature, but can be converted to a mesophase state by heating to a high temperature (600° C. or higher).

In other words, if a polycyclic aromatic compound in this state is spun alone, made infusible, and fired, it is possible to spin it at a relatively low temperature. Similar to using aromatic compounds,
High modulus carbon fiber can be used.

Furthermore, even if the polycyclic aromatic compound in the pre-mesophase state contains a small amount of the polycyclic aromatic compound in the mesophase state and/or isotropic state, the silicon-containing polycyclic aromatic polymer which is the final product It does not affect the nature of the

The polycyclic aromatic compound (2) obtained by the above production method generally has a melting point of 200 to 350°C, a weight average molecular weight of 200 to 6000, and a quinoline soluble content of 5% or less.

A random copolymer (1) and a polycyclic aromatic compound (2) are heated to react and/or melted at 200 to 500°C,
A silicon-containing polycyclic aromatic polymer is obtained.

The usage ratio of the polycyclic aromatic compound (2) is preferably 5 to 900 parts per 11,100 parts of the random copolymer (11,100 parts). If it is less than 5 parts, the polycyclic aromatic compound (2) will be insufficient, so Even if the resulting polymer is inorganicized, highly elastic fibers or molded articles cannot be obtained, and if the amount exceeds 900 parts, it is difficult to obtain fibers with excellent wettability to the matrix or with oxidation resistance due to the lack of silicon component. A molded article with improved properties cannot be obtained.

If the above-mentioned melt mixing temperature is lower than 200"C, an unmelted portion will be generated and the system will be non-uniform.
If the temperature is higher than 0.degree. C., the condensation reaction will proceed vigorously, the resulting polymer will have a high melting point, and its fluidity will be lost.

(Effects) Since the silicon-containing polycyclic aromatic polymer according to the present invention contains an organosilicon copolymer and a polycyclic aromatic compound (2) in the polymer, this polymer can be melt-spun, infusible, and calcined. By doing this, Si and C are deposited on ultrafine graphite crystals.
It is possible to obtain a carbon-based inorganic fiber having a structure in which amorphous and/or β-SiC ultrafine particles consisting of , and 0 are dispersed, and has high strength and elasticity, and has excellent wettability with plastics. In this way, there was no existing fiber that could satisfy both mechanical properties and wettability with plastics.
In particular, there are great expectations for the development of applications for FRP.

In addition, the fibers obtained from the silicon-containing polycyclic aromatic polymer of the present invention enable use of carbon fibers in high-temperature oxidizing atmospheres, and can be made into oxidation-resistant carbon-based materials by molding the polymer of the present invention. Obtainable. Further, the present invention greatly contributes from the viewpoint of effective use of pitch.

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

Reference Example 1 (Production method of organosilicon polymer) 5I! 2.5 of anhydrous xylene in a three-hole flask! and 400 g of sodium were added thereto, heated to the boiling point of xylene under a nitrogen gas stream, and dimethyldichlorosilane 11 was added dropwise over 1 hour. After the dropwise addition was completed, the mixture was heated under reflux for 10 hours to form a precipitate. The precipitate was filtered and washed with methanol and then water to obtain 420 g of white powder polydimethylsilane.

400 g of this polydimethylsilane was transferred to a 3I! equipped with a gas introduction tube, a stirrer, a cooler, and a distillation tube. The mixture was charged into a Golof flask and heated at 420° C. under a nitrogen flow of 50 mff/min without stirring to obtain 350 g of a colorless and transparent slightly viscous liquid in a distillation receiver.

The number average molecular weight of this liquid was 470 as measured by vapor pressure osmosis.

When the infrared absorption spectrum of this substance was measured, it was found that 6
5iC at 50-900cII+''' and 1250cm-'
Absorption of H3, absorption of 5i-H at 2100 cm-', 10
Si CHz near 2102O' and 1355cm-'
Absorption of Si, absorption of CH at 2900c+n-' and 2950cm-' was observed, and when the far-infrared absorption spectrum of this material was measured, 5i-S was observed at 380cm-'.
Since absorption of i is observed, the obtained liquid substance is
Mainly (S i CHz ) bonding units and (Si-
It was found to be an organosilicon polymer consisting of Si) bond units and having a hydrogen atom and a methyl group in the silicon side chain.

From the measurement results of nuclear magnetic resonance analysis and infrared absorption analysis, this silicon polymer is a polymer in which the ratio of the total number of (Si CH2) bond units to the total number of (Si-Si) bond units is approximately 1:3. It was confirmed that there is.

300 g of the above organosilicon polymer was treated with ethanol to remove low molecular weight substances to obtain 40 g of a polymer having a number average molecular weight of 1200.

When the infrared absorption spectrum of this substance was measured, absorption peaks similar to those above were observed, and this substance mainly consists of (S 1-CH2) bond units and (Si-Si) bond units, with hydrogen in the silicon side chain. It turned out to be an organosilicon polymer having atoms and methyl groups.

According to the measurement results of nuclear magnetic resonance analysis and infrared absorption analysis, this organosilicon polymer is a polymer in which the ratio of the total number of (Si CH2) bond units to the total number of (Si-Si) bond units is approximately 7:1. This was confirmed.

Reference Example 2 (Production method for FCC slurry oil) Fluid catalytic cracking and rectification of petroleum fractions with higher boiling points than light oil are carried out at a temperature of 500°C in the presence of a silica/alumina cracking catalyst, and the bottom of the column is A residue was obtained. 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 fraction of 0.55 as determined by nuclear magnetic resonance analysis.

Example 1 (First step) 100 g of the FCC slurry oil obtained in Reference Example 2 was heated to 420"C under a nitrogen gas flow, and the distillate at the same temperature was distilled off, and the residue was filtered while hot at 150°C. Then, the unmelted portion at the same temperature was removed to obtain 57 g of pitch from which light components were removed.

This light fraction removed pitch contained 60% xylene insoluble matter.

Add 25 g of the organosilicon polymer obtained in Reference Example 1 and 20 ml of xylene to 57 g of this light fraction removal pinch, raise the temperature with stirring, distill off the xylene, and react at 400°C for 6 hours to obtain 43 g of random copolymer ( 1) was obtained.

As a result of infrared absorption spectrum measurement, this random copolymer (1) was found to have SiH bonds (I
R: 2100 cnr') and new 5i-C (
Hensen ring carbon) bond (IR: 1135c++r')
It was found that some of the silicon atoms in the organosilicon polymer had a portion directly bonded to a polycyclic aromatic ring.

Further, this copolymer contained no xylene-insoluble portion, had a weight average molecular weight of 1450, and a melting point of 265°C.

(Second step) 400 g of FCC slurry oil obtained in Reference Example 2 and 1
．． After hydrogenating 300 g of 2,3,4-tetrahydroquinoline at 450° C. for 10 minutes in an autoclave, the tetrahydroquinoline was distilled off to obtain hydrogenated pitch.

This pitch was placed in a metal container, immersed in a tin bath under reduced pressure of 10 mmHg, and heat treated at 450° C. for 10 minutes to obtain 62 g of pitch.

The resulting pitch has a melting point of 230°C and a softening point of 238°C.
It was a polycyclic aromatic compound (2) with a quinoline solubility of 2%.

(Third step) Random copolymer (1) obtained in the first step 40 g
and 80 g of polycyclic aromatic polymer (2) obtained in the second step.
were melt-mixed at 350° C. for 1 hour under a nitrogen atmosphere to obtain a silicon-containing polycyclic aromatic polymer in a uniform state.

This silicon-containing polycyclic aromatic polymer was optically isotropic, but had a xylene insoluble content of 45% and a melting point of 251°C, and was hydrogenated under mild conditions and subjected to gel permeation chromatography. The weight average molecular weight (
M9) was measured and found to be Mw=1080.

This silicon-containing polycyclic aromatic polymer was heated to 1000°C in air.
The resulting ash was subjected to alkali melting and hydrochloric acid treatment, and after dissolving in water, the silicon concentration of the aqueous solution was measured using an high frequency plasma emission spectrometer (ICP). The silicon content in the aromatic polymer was found to be 5.8%.

Example 2 (First step) The ratio of the light fraction removed pitch component and the organosilicon polymer component was changed to 60 parts:40 parts, and the copolymerization temperature was set to 420"C12.
A random copolymer (1) was obtained in the same manner as in Example 1 except for changing the time. This copolymer has a melting point of 238°C,
The weight average molecular weight (M) was 1400, and no quinoline-soluble matter was present.

(Second step) The FCC oil obtained in Reference Example 2 was heated in an autoclave under a nitrogen atmosphere at 430°C under an autogenous pressure of 95 kg/c+fl (
The hydrogen partial pressure was 21 kg/c+lI. ) After treatment for 1 hour under the conditions of A polycyclic aromatic compound (2) with a content of 5% was obtained.

(Third step) The charging ratio of the random copolymer (1) and the polycyclic aromatic polymer (2) was 40 parts:60 parts, and the melt mixing temperature was 38 parts.
Example 1 except that the temperature was 0°C and the melt mixing time was 30 minutes.
A silicon-containing polycyclic aromatic polymer was obtained in the same manner as above. The obtained polymer was optically isotropic, but had a xylene insoluble content of 39%, a weight average molecular weight (Mw) of 1210, a silicon content of 8.2%, and a melting point of 258°C. Ta.

Comparative Example 1 (First Step) 200 g of the FCC slurry oil obtained in Reference Example 2 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 mft of xylene at 130°C and 69 g of xylene insoluble matter was removed. 45 g of the organosilicon polymer obtained in Reference Example 1 was added to 45 g of the xylene soluble part in the obtained pitch. , Copolymerization was carried out at 400° C. for 6 hours to obtain 32 g of random copolymer.

(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 a nitrogen atmosphere to obtain 41 g of heat-treated pitch.

(Third step) 30 g of the random 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° and 5 hours. The obtained product had a weight average molecular weight (M8) of 1750 and a silicon content of 10.5%, but had a low melting point of 198°C and was optically isotropic, containing only 11% of xylene-insoluble matter. It was a chemical polymer.

Comparative Example 2 50 g of the organosilicon polymer obtained in Reference Example 1 was added to 100 g of the light bone-removed pitch obtained in Example 1 and reacted at 400° C. for 6 hours to obtain 79 g of random copolymer.

The resulting copolymer has a melting point of 252°C and a silicon content of 15
%, the average weight molecular weight (Ml, l) is 1400,
It contained no xylene-insoluble matter and no mesophase portion was present.

Example 3 The silicon-containing polycyclic aromatic polymers obtained in Examples 1 and 2 were used as spinning dopes, and melt-spun using a nozzle with a diameter of 0.3 mm. The obtained precursor yarn is passed through air circulation,
It was made infusible at 300°C and fired at 1300°C under an argon stream to obtain carbonized inorganic fibers.

The thread diameter, tensile strength, and tensile modulus of this fiber are, respectively,
In the case of the dope of Example 1, 11 μ, 288 kg/+n
m2.24t 7mm2, and in the case of the dope of Example 2, it was 9μ, 261 kg/mm2.21t 7mm2.

Scanning electron microscopy revealed that both side fibers had a cross-sectional structure similar to the radial structure used in pitch fibers, and that the mesophase component in the dope was oriented in the fiber axis direction during the spinning, infusibility, and firing processes. It showed that.

Comparative Example 3 The polymers obtained in Comparative Examples 1 and 2 were spun, infusible, and fired under the same conditions as in Example 9 to obtain fired yarn.

The thread diameter, tensile strength, and tensile modulus of each fiber are 17 μ, 105 kg/k2, m, l t 7 mm2, for the dope of Comparative Example 1, and 16 μ, for the dope of Comparative Example 2, respectively. 75 kg/mm”, 5. Ot 7m
It was m2.

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

Claims (2)

[Claims] (1) (A) Mainly composed of a bonding unit (Si-CH_2), or a bonding unit (Si-CH_2) and a bonding unit (Si-Si), with hydrogen atoms, lower alkyl groups, phenyl groups and an organosilicon polymer unit having a substituent selected from the group consisting of silyl groups, and (B) a polycyclic aromatic compound unit mainly in a pre-mesophase state, in which at least a part of the silicon atoms in (A) are ,
A silicon-containing polycyclic aromatic polymer, which is bonded to the carbon atom of the aromatic ring of (B). (2)i) Mainly composed of a bonding unit (Si-CH_2), or a bonding unit (Si-CH_2) and a bonding unit (Si-Si), with a hydrogen atom, a lower alkyl group, a phenyl group, and a silyl group in the side chain of the silicon atom. Silicon of an organosilicon polymer having a substituent selected from the group consisting of groups, and in which the ratio of the total number of bonding units (Si-CH_2) to the total number of bonding units (Si-Si) is in the range of 1:0 to 20. 100 parts by weight of a random copolymer in which at least some of the atoms are bonded to the carbon atoms of the aromatic ring of a polycyclic aromatic compound that is petroleum-based or coal-based pitch or a heat-treated product thereof; and ii) petroleum-based or coal-based pitch. After hydrogenating the pitch, 5 to 900 parts by weight of a polycyclic aromatic compound mainly in a pre-mesophase state obtained by heat treatment under reduced pressure is subjected to a heating reaction and/or heating melting at a temperature in the range of 200 to 500°C. A method for producing a silicon-containing polycyclic aromatic polymer, characterized in that: