JPH032298A - Production of meso-phase pitch - Google Patents

Abstract

PURPOSE:To obtain a meso-phase pitch suitable for the production of a high- performance carbon fiber having decreased melting and gluing tendency by blowing a non-oxidizing gas into a meso-phase pitch under specific condition, thereby removing light components from the pitch. CONSTITUTION:A meso-phase pitch is produced by heat-treating a carbonaceous raw material and separating from the heat-treatment product. The objective meso-phase pitch can be produced by introducing a non-oxidizing gas such as N2, Ar, He, H2, steam, CO2, methane, ethane or propane into the above raw meso-phase pitch at about 310-350 deg.C under stirring at a rate of 0.1-10m<3>/hr per 1kg of the charged pitch for 1min to 2hr, thereby removing the light components from the pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing mesophace pitch suitable for producing carbon fibers. More specifically, the present invention relates to a method for producing mesoface pitch suitable for producing high-performance carbon fibers with reduced fusion and agglomeration.

[Conventional technology]

BACKGROUND ART Conventionally, there has been a demand for the development of high-performance materials having light weight, high strength, high modulus of elasticity, etc. in various industrial fields such as automobiles, aircraft, etc., and carbon fiber has been attracting attention from the viewpoint of strength.

Currently, the mainstream of carbon fibers on the market is still PAN-based carbon fibers made from polyacrylonitrile, but carbon fibers made from coal or petroleum pitches are also inexpensive, have a high yield in the carbonization process, and have good elasticity. It is regarded as important due to its advantages such as the ability to obtain fibers with high fiber content, and active research and development efforts are being carried out.

Carbon fiber obtained from optically isotropic pitch has strength,
Although both the modulus of elasticity is low, high-performance carbon fibers can be obtained from optically anisotropic pitch (i.e., mesoface pitch) obtained by heat-treating optically isotropic pitch. These methods include, for example, simply heat-treating the horn
, Extracting optically isotropic pitch with a solvent and heat-treating the insoluble matter (JP-A-54-160427, etc.), Heat-treating while blowing inert gas (JP-A-58-16)
8687), heat treatment after partial hydrogenation (JP-A-57-100186 and JP-A-58-18421), pyrolysis polycondensation is stopped halfway, and sedimentation separation or centrifugation is carried out depending on the difference in specific gravity. to obtain a highly concentrated anisotropic pitch (
Tokuko Showa 61. 38755 and 62-24036) have been proposed.

However, these various mesoface pitches contain air bubbles or light components generated during heat treatment, and when such pitches are melt-spun, they foam, making it impossible to maintain a stable spinning state, and resulting in poor yields. The resulting fibers cause problems such as thread breakage and fluff, making it difficult to obtain high-performance products.

In order to solve these problems, there are methods for defoaming mesoface pitch and removing light components, such as methods of forcibly developing mesoface-containing pitch into a liquid film under reduced pressure, or forming pores into rivulets in a molten state. A method of flowing down into a reduced pressure space (Japanese Patent Application Laid-Open No. 62-116688, JP-A No. 62-1192)
A method (Japanese Patent Application Laid-open No. 158786/1986) has been proposed in which precursor pitch pulverized to 60 mesh or less is heated and melted under reduced pressure of 5 trithier or less.

Furthermore, the presence of adhesion in carbon fibers is not preferable because it results in a decrease in the physical properties of the carbon fibers or a decrease in homogeneity when used as a composite material. As a result of studies conducted by the present inventors, it has been found that the adhesion of carbon fibers varies depending on the amount of light components in the pitch.

[Problem to be solved by the invention]

However, the methods described in JP-A-62-116688, JP-A-62-119292, and JP-A-62-158786 are aimed at defoaming the pitch in order to improve the spinnability of the pitch. This method attempts to remove air bubbles in the pitch or extremely light components in the pitch, and these methods cannot remove the light components necessary to prevent carbon fibers from sticking. .

Therefore, an object of the present invention is to provide a method for producing mesoface pitch that overcomes these problems, that is, provides a carbon fiber with reduced fusion and agglutination, and includes a simple method for removing light components. .

[Means to solve the problem]

According to the present invention, a heat treatment step of heat-treating a carbonaceous raw material to produce a mesoface-containing pitch, and a mesoface step of separating the produced mesoface-containing pitch into a mesoface pitch component and a non-mesoface pitch component to obtain a mesoface pitch. In a method for producing mesoface pitch including a pitch separation step, the mesoface pitch obtained in the mesoface pitch separation step is heated at about 310 to about 350°C.
Provided is a method for producing mesoface pitch, which comprises performing a non-oxidizing gas blowing treatment while stirring at a temperature of
Further, the mesoface pitch obtained in the mesoface pitch separation step is subjected to vacuum degassing treatment at a temperature of about 310 to about 350°C while stirring to remove light components contained in the pitch. There is provided a method for producing mesoface pitch, characterized in that about 310
A method for producing mesoface pitch, characterized in that light components contained in the pitch are removed by blowing a non-oxidizing gas and vacuum degassing treatment at a temperature of ~350°C with stirring. provided.

That is, in the method for producing mesoface pitch of the present invention, the mesoface pitch obtained in the mesoface pitch separation step is further processed into an approximately 31%
By performing non-oxidizing gas blowing treatment or (and) vacuum degassing treatment while stirring at a temperature of about 0 to about 350 degrees Celsius, light components are removed and carbon fibers are made, especially reducing fusion and agglutination. This method provides a mesoface pitch that provides high performance products.

In this specification, "fusion" refers to a state in which multiple filaments are bonded and integrated to the extent that they form a single tissue, and "adhesion" refers to a state in which multiple filaments are simply in contact. This means that the structures of each filament are not integrated but exist separately.

In addition, the mesoface pitch (i.e., optically anisotropic pitch) referred to in the present invention is a pitch in which brightness is observed by polishing the cross section of a pitch lump solidified at room temperature and rotating crossed Nicols with a reflective polarizing microscope. In other words, it means a pitch in which most of the pitches are substantially optically anisotropic, and pitches that are optically isotropic without any brilliance are referred to as non-mesoface pitches (optically isotropic) in this specification. It is called directional pitch).

Therefore, the mesophase pitch in this specification includes not only a pure optically anisotropic pitch but also an optically isotropic phase contained in an optically anisotropic phase in the form of a sphere or irregularly shaped islands. This also includes cases where On the contrary, non-mesophase pitches also include those containing a small amount of optically anisotropic phase in optically isotropic pitches. There are also two types of memface: those that are insoluble in quinoline or pyridine, and those that contain a large amount of components that are soluble in quinoline or pyridine.
The mesophase referred to herein is primarily the latter mesophase.

Note that the mesophase content in the present invention is determined by observing and photographing a sample under crossed Nicols using a polarizing microscope and measuring the area ratio occupied by the mesophase portion in the sample. The softening point of pitch in the present invention refers to the solid-liquid transition temperature of pitch, which is determined from the peak temperature of absorption and release of latent heat during melting or solidification of pitch using a differential scanning calorimeter. be. This temperature agrees within a range of ±10°C with those measured by other ring and ball methods, micro melting point methods, etc. for pitch samples.

Hereinafter, the method for manufacturing mesoface pitch of the present invention will be explained in detail.

The present invention includes a heat treatment step of heat-treating a carbonaceous raw material to produce mesoface-containing pitch, and a mesoface pitch separation step of separating the generated mesoface-containing pitch into a mesoface pitch component and a non-mesoface pitch component to obtain mesoface pitch. It also includes a non-oxidizing gas blowing process and/or a vacuum degassing process to remove light components.

As the carbonaceous raw material for producing mesoface pitch used in the present invention, various so-called heavy hydrocarbon oils, tars or pitches can be used.

Examples of these raw materials include various heavy petroleum oils, asphalt (e.g. straight asphalt,
blown asphalt, etc.), pyrolysis tar, catalytic cracking tar, heavy oil, tar, pitch obtained by carbonization of coal, or heavy liquefied coal produced from a coal liquefaction process, etc. Suitable examples include catalytic cracking residual oil of petroleum. These are used after being subjected to preliminary treatments such as filtration and solvent extraction, if necessary. Furthermore, in order to stabilize the quality of the mesophase pitch produced by the present invention, carbonaceous pitch, which partially already contains a small amount of mesophase pitch as a result of the pyrolysis polycondensation reaction, may be used as a raw material.

The heat treatment step for producing mesophase-containing pitch is a step of performing a menization reaction (defined as a reaction that produces mesophase) by a thermal decomposition polycondensation reaction. The thermal decomposition polycondensation reaction is a reaction in which the thermal decomposition reaction of one heavy hydrocarbon and the polycondensation reaction occur in parallel as main reactions.
Refers to a reaction that changes the chemical structure of pitch component molecules,
As a result of this reaction, scission of the paraffin chain structure, dehydrogenation, ring closure, development of a planar structure of polycyclic condensed aromatics due to polycondensation, etc. proceed.

For this reaction, the carbonaceous feedstock is heated to about 380°C to about 460°C.
, preferably heat treated at 400-430°C. If the reaction temperature exceeds about 460° C., the volatilization of unreacted raw materials increases, the softening point of mesophase increases, and coking is likely to occur, which is unsuitable.

On the other hand, if the temperature is lower than about 380°C, the reaction will take a long time, which is not preferable.

In the heat treatment process, stirring is performed to prevent local overheating and to ensure uniform reaction, but in addition, stirring is performed under reduced pressure or as necessary to quickly remove low molecular weight substances generated as a result of thermal decomposition. This can be carried out while blowing an inert gas into the reactor. In this case, the inert gas may be one that has sufficiently low chemical reactivity with the pitch at the reaction temperature, such as nitrogen, water vapor, carbon dioxide, light hydrocarbon gas, or a mixed gas thereof.

It is preferable to preheat these inert gases before blowing them in without lowering the reaction temperature.

The inert gas contains cracked oil and cracked gas.

The cracked oil and cracked gas are extracted from the top of the reactor and passed through a condenser, scrubber, separation tank, etc.

Thereafter, it is also possible to recycle and use the inert gas.

This heat treatment reactor can be of any type as long as it is a liquid-phase pyrolysis device, but usually one consisting of a cylindrical container is used, with a raw material supply port, cracked oil, cracked gas, and inert gas. The reactor is provided with a discharge port, a pitch outlet, a non-mesoface pitch inlet to be described later, etc., a stirring device, etc. is provided inside the reactor, and a heater for heating the raw material, etc. is provided outside the reactor. Incidentally, the reaction operation may be carried out by any method such as batch, semi-patch or continuous method.

In the heat treatment step of the present invention, the mesophase component is brought to a state in which the produced pitch is substantially free of low molecular weight decomposition products and unreacted substances and contains about 30 to about 80%, preferably about 380 to about 70%, of the mesophase component. When this happens, it is preferable to stop the process and transfer to the next mesoface pitch separation process. This is because in order to obtain a high yield of homogeneous mesophase pitch with a low softening point in the mesophase pitch separation process, the pitch yield after the pyrolysis polycondensation reaction must be high and the mesophase content must be approximately 20%. This is because it is preferable that the softening point is 260° C. or lower by about 80%. If the mesophase component in the pitch after the pyrolysis polycondensation reaction is less than 20%, the yield of mesophase pitch in the next separation step will be extremely low. If the temperature is higher than 260° C., the separability in the separation process will be poor, making it impossible to obtain mesoface pitch with a high concentration, and the obtained mesoface pitch will have a high softening point. The mesoface-containing pitch obtained in this process has a diameter of 5.
Spherical particles with a diameter of 00 μm or less, preferably 300 μm or less are suitable.

In the present invention, the mesoface-containing pitch produced in the heat treatment step is sent to the first mesoface pitch separation step, where it is separated into mesoface pitch components and non-mesoface pitch components. Various known solid-liquid separation methods can be appropriately employed to separate mesoface pitch and non-mesoface pitch, but in particular, a separation method using a difference in specific gravity (see Japanese Patent Publication No. 38755/1983) , Publication No. 62-24036) is preferably used, and particularly in industrial production, it is preferable to use a centrifugal separation method.

In the centrifugal separation method, the mesophase-containing pitch produced in the heat treatment process is centrifuged in its molten state.The mesophase component has a higher specific gravity than the isotropic component, so it quickly settles and coalesces and grows. The mesophase accumulates in the lower layer (layer in the direction of centrifugal force), and the mesophase forms a continuous phase with approximately 80% or more of it, and contains a slight isotropic phase in the form of islands or minute spherules. The face pitch is the lower layer, while the upper layer is mostly an isotropic phase, and the mesophase is a non-mesoface pitch in which the membranes are dispersed in the form of minute spherical bodies, and the interface between the upper and lower layers is This is a method that is clear and utilizes the fact that the specific gravity of the upper layer and the lower layer in the molten state is significantly different, and the lower layer is separated and taken out from the upper layer to separate mesoface pitch and non-mesoface pitch. Note that centrifugal separation is a processing operation that applies high-speed rotation to a fluid, collects a phase with a higher specific gravity in the fluid to a lower layer (in the direction of centrifugal force), and separates this, and is one of its embodiments. As such, operation using a so-called centrifugal separator, particularly a continuous type centrifugal separator that continuously separates and discharges a heavy phase and a light phase, is advantageously used.

The temperature in this step depends on the magnitude of centrifugal force, but is preferably above the softening point of the mesophase-containing pitch, preferably from 280°C to
The temperature is 400°C, more preferably 320°C to 380°C. A predetermined constant temperature within this range may be used, and the temperature does not necessarily have to be constant.

In this step, the main purpose is to deposit and coalesce many parts of the mesophase in the direction of centrifugal force, and it is necessary to avoid thermal decomposition and polycondensation reactions as much as possible. Therefore, a temperature higher than 400° C. is not preferable, and a temperature higher than necessary makes it difficult to operate the centrifugal separator continuously for a long time, but there is no such problem at the above-mentioned temperature. Furthermore, at temperatures lower than the above range, the viscosity of the pitch system as a whole, especially of the mesophase component, is high, making it difficult for the isotropic phase co-precipitated in the lower mesophase to come off, resulting in a long and extremely large centrifugal acceleration. However, separation becomes difficult.

The centrifugal force acceleration of the centrifugation operation may be of any value, but the mesophase component (heavy phase) and non-mesophase component (light phase) can be efficiently separated in a short time by shortening the residence time. Preferably 1,0OO
G or more, particularly in the range of 10,000 to 40,000 OOG can be adopted. Note that there are restrictions on equipment when using 50,000 OOG or more.
% or more mesoface pitch in a short time.

Economically obtainable.

In addition, the non-mesoface pitch separated in this step can be converted into mesoface-containing pitch by applying heat treatment again, so in a preferred embodiment, this non-mesoface pitch is subjected to the heat treatment step at a specific point in time. It is circulated.

This cycle causes the physical properties of the pitch produced in the heat treatment process to become the same as those of non-mesoface pitch in order to avoid widening the residence time distribution (i.e., molecular weight distribution) of the mesophase in the heat treatment process. It is preferable to do this at the same time.

This circulation of non-mesoface pitch causes it to undergo heat treatment again, improving the final pitch yield.

In the present invention, it is also possible to add an appropriate finishing heat treatment step immediately after the mesoface pitch separation step. That is, by using a particularly short residence time in the separation step, the softening point is sufficiently low, but the mesophase content is about 80
% ~ 90%, which is slightly insufficient, is then subjected to a thermal heavy-duty reaction treatment at a temperature of 300°C to 430°C, so that the properties of mesoface pitch are within narrow quality control limits. It is also possible to adopt a method of adjustment so that the

Mesoface pitch containing 80 to 90% mesophase contains 10 to 2 parts of isotropic components, but this isotropic component can be further reduced by adding a small amount of heat-heavy reaction treatment, and it can also be softened. It is known that the mesophase content gradually increases, so by thermograviding the separated pitch at appropriately controlled temperatures and treatment times, the mesophase content can be increased to 90% or more, preferably 95% or more. can be adjusted to

Further, in the present invention, after the mesoface pitch separation step, a solvent extraction step for removing quinoline soluble components, and further a solvent extraction step for removing n-hebutane soluble components, etc. may be provided. However, when the finishing heat treatment step is provided, a mild hydrogen treatment step may be provided immediately after the final heat treatment step to control excessive rise in the softening point of the pitch.

In the present invention, the mesoface pitch separated in the mesoface pitch separation process (or the mesoface pitch that has undergone the final heat treatment, etc., if the above-mentioned final heat treatment, etc., has been applied) is then subjected to a non-alcohol treatment for removing light components. The product is sent to an oxidizing gas blowing process and/or a vacuum degassing process. That is,
The mesoface pitch contains a small amount (usually 0.1 to 3 weight) of light components, but as described above, this component is stable in the carbon fiber manufacturing process consisting of melt spinning, infusibility, and carbonization steps. This makes it impossible to maintain the spun state in which the yarn is spun, causing problems such as melting and sticking in the product. In the present invention, non-oxidizing gas blowing treatment and/or vacuum degassing treatment are performed for this purpose, and these treatments reduce the molecular weight from mesoface pitch to approximately 500 (measured by electrolytic desorption/mass spectrometry). Light components up to 100% are efficiently removed.

In this process, the mesoface pitch is heated to about 310 to about 350°C.
However, at temperatures below about 310°C, the fluidity of the pitch decreases and the removal efficiency of light components decreases, while at temperatures above about 350°C, the removal efficiency of the pitch decreases. This is not preferred because the polycondensation reaction progresses and adversely affects the physical properties of the pitch.

Normally, this non-oxidizing gas blowing process is carried out using a deaerator that blows non-oxidizing gas into the pitch and discharges the light components from the top. It is preferable to provide a cooler (air cooling is also possible) for rapidly removing trace amounts of light components by adhering and solidifying them (solidifying because of their high softening point) without refluxing them. Also,
A cooler may be provided inside the deaerator.

As the non-oxidizing gas, nitrogen, argon, helium, hydrogen, steam, carbon dioxide, methane, ethane, propane, etc. are used alone or in combination, and nitrogen gas is usually used. The blowing of the non-oxidizing gas is carried out by flowing a large amount of gas at a rate of 0.1 to 10 rrr/hr per kg (injection pitch) for 1 minute to 2 hours. The non-oxidizing gas can also be recycled and reused after the entrained and removed light components are separated and removed by a light component removal device. Note that the non-oxidizing gas may be blown onto the liquid surface of the pitch, or may be blown into the pitch to further increase efficiency.

The vacuum degassing treatment is usually performed at a pressure of 50 torr or less, preferably 10 torr or less.
The reaction is carried out under a high vacuum of not more than torr, preferably not more than 1 torr, with stirring for 1 minute to 2 hours. It is preferable to provide a cooler for adhering and solidifying light components also in the upper part of this deaerator.

Further, when non-oxidizing gas blowing treatment and vacuum degassing treatment are used together, the degassing time becomes shorter, so it can be adopted as a more effective method. In this case, the amount of non-oxidizing gas blown is 0.001 to 0.00 per kg of pitch. Lrr
f/hr is sufficient.

In the present invention, the amount of light components that can be degassed (i.e., 0.
50 to 100% of the amount removed when degassing at 350° C. for 1 hour under a vacuum of 0.001 torr is removed.

If the light content is removed by less than 50%, the reduction in fusing and agglomeration of the fiber will be insufficient when it is made into carbon fiber, which is not preferable.

The pitch obtained in this process is continuously taken out of the system and remains in a liquid state or is solidified to become a product.

From this process, the softening point is sufficiently low, that is, 230 to 32
Pitches in the 0°C range are obtained.

The pitch obtained as described above is melt-spun according to a known method, and the obtained pinch fibers are made infusible, carbonized, and optionally further graphitized, resulting in excellent spinnability, especially fusion and agglutination. It is possible to obtain high-performance pitch-based carbon fibers and graphite fibers with reduced .

〔Effect of the invention〕

According to the method of the present invention, the mesoface pitch separated in the mesoface pitch separation step is further subjected to a non-oxidizing gas blowing treatment and/or a vacuum degassing treatment to remove light components. , it is possible to sufficiently and effectively remove the light components that are mainly generated during heat treatment of pitch and cause fusing and agglomeration of the fibers when made into carbon fibers, resulting in reduced fusing and agglutination and high performance. It is possible to stably produce carbon fibers, and by further proceeding to graphitization, pitch-based graphite fibers with high strength and ultra-high modulus can be produced.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is of course not limited thereto.

Example 1 A carbonaceous pitch containing about 5 colors of optically anisotropic phase and having a softening point of 235° C. was used as a precursor pitch. This precursor pitch was separated using a cylindrical centrifugal separator at 370° C. to obtain a pitch with high optical anisotropy.

The optically anisotropic pitch obtained is 98 times the optically anisotropic phase.
%, and the softening point was 265°C.

1 kg of the above pitch was put into a vacuum deaerator equipped with a stirrer equipped with a cooler for adhering and solidifying light components on the upper part and a light fraction recovery device in the gas exhaust line, heated to 340°C, and heated under the condition of ITorr. Vacuum degassed for 30 minutes. The light fraction removed at this time was 1.5% (by weight), which means that 94% of the removable light fraction was removed. (The amount of light fraction that can be removed was determined by degassing at 0,001 Torr and 350°C for 1 hour.) The obtained optically anisotropic pitch was passed through a spinning machine with a 500-hole spinneret, and was heated to 200 mmHg at 340°C. The material was extruded and spun using a nitrogen gas pressure of .

The spun pitch fibers were wound for 10 minutes at a speed of about 500 m/min on a bobbin that rotated at high speed provided at the bottom of the nozzle.

A portion of the pitch fiber bundle thus obtained was taken out and infusible while being heated from 150° C. to 300° C. over 60 minutes in air.

This infusible pitch fiber was heated for 15 minutes in an inert gas atmosphere.
Carbon fibers were obtained by raising the temperature to 00'C. This fiber had a thread diameter of io, oμl, a tensile strength of 3.3 GPa, a tensile modulus of 275 GPa, and a degree of adhesion of 10%.

In addition, this carbon fiber was heated to 2500°C in an inert gas atmosphere.
The graphite fiber obtained by raising the temperature to 100% had a thread diameter of 9.8 IJs, a tensile strength of 3.4 GPa, a tensile modulus of 700 GPa, and a degree of adhesion of 22%.

In addition, the degree of adhesion (%) is determined by cutting the fiber bundle into a width of 3 mm.
This was determined using the following formula by immersing this in ethanol, blowing air into it for 30 seconds, and then counting the total number of stuck filaments (N) under a microscope at 20x magnification. .

Adhesion degree = (N/X)X100 (%) However, X indicates the total number of filaments counted, and N indicates the total number of stuck filaments.

Example 2 A cooler for adhering and solidifying light components at the top, a gas blowing pipe for blowing non-oxidizing gas into the bottom, and a light fraction recovery device for circulating and reusing the non-oxidizing gas in the gas discharge line. Using a deaerator with a stirrer equipped with piping,
Pitch temperature 340'C5 Nitrogen gas injection amount 1rn'/h
The treatment was carried out in the same manner as in Example 1, except that the nitrogen gas blowing treatment was carried out under the conditions of r. The light fraction removed at this time was 0.8%, which corresponds to 51% of the removable light fraction.

This pitch was melt-spun, infusible, carbonized, and graphitized in the same manner as in Example 1, and the graphite fiber obtained had a degree of adhesion of 35%.

Example 3 A vacuum deaerator with a stirrer was used, which was equipped with a cooler for adhering and solidifying light components at the top, a gas blowing pipe for blowing non-oxidizing gas into the bottom, and a light fraction recovery device in the gas discharge line. pitch temperature 340℃, nitrogen gas amount 0.05r
The process was carried out in the same manner as in Example 1, except that vacuum degassing was performed for 5 minutes under the conditions of ri'/hr and ITorr. In this case, the light fraction removed was 1.5 kg, which corresponded to 94% of the amount of light fraction that could be removed.

This pitch was melt-spun, infusible, carbonized, and graphitized in the same manner as in Example 1, and the graphite fiber obtained had a degree of adhesion of 21%.

Comparative Example 1 Using the same device as used in Example 1, the pitch was set to 34
The same process as in Example 1 was carried out, except that the sample was heated to 0° C. and vacuum degassed for 3 minutes under ITorr conditions.

In this case, the light fraction removed was 0.2%, which corresponds to 13% of the amount of light fraction that can be removed.

This pitch was melt spun in the same manner as in Example 1, but
The spinnability was good and there was no yarn breakage.

The pitch fiber thus obtained was treated to be infusible and carbonized in the same manner as in Example 1. The yarn diameter of the carbon fiber obtained was io
,o,, tensile strength is 2,5GPa, tensile modulus is 27
0 GPa, and the degree of adhesion was 51%.

Further, graphite fiber obtained by treating this carbon fiber in the same manner as in Example I had a yarn diameter of 9.8 and a tensile strength of 2.9 GPa.

The tensile modulus was 690 GPa, and the degree of adhesion was 80%.

Comparative Example 2 Example 1 except that no light fraction removal treatment was performed.
When treated in the same manner as above, bubble breakage was severe during spinning, and stable spinning could not be achieved.

Comparative Example 3 Pitch was supplied at a temperature of 390° C. using a gear pump to a vacuum deaerator having a rotating disk inside for developing the pitch as a liquid film. The pressure inside the device is 10 Tor
The pitch from which light components had been removed was taken out from the bottom of the apparatus. At that time, the amount of light components removed was 0.2%, which corresponded to 13% of the total amount of removable light components. In addition, in this case, since the pitch was treated at high temperature, some alteration was observed.

When this pitch was melt-spun in the same manner as in Example 1, the spinnability was good.

When the obtained pitch fibers were subjected to infusible, carbonized, and graphitized treatments in the same manner as in Example 1, the degree of adhesion of the obtained graphite fibers was 82%.

Patent applicant: Toa Fuel Industries Co., Ltd.

Claims (1)

[Claims] (1) A heat treatment step of heat-treating a carbonaceous raw material to produce mesoface-containing pitch, and separating the produced mesoface-containing pitch into a mesoface pitch component and a non-mesoface pitch component to obtain mesoface pitch. In a method for producing mesoface pitch including a mesoface pitch separation step, a non-oxidizing gas is blown into the mesoface pitch obtained in the mesoface pitch separation step at a temperature of about 310 to about 350° C. while stirring. A method for producing mesoface pitch, which comprises performing a treatment to remove light components contained in the pitch. (2) A heat treatment step in which a carbonaceous raw material is heat-treated to produce mesoface-containing pitch, and a mesoface pitch separation step in which the generated mesoface-containing pitch is separated into a mesoface pitch component and a non-mesoface pitch component to obtain mesoface pitch. In the method for producing mesoface pitch, the mesoface pitch obtained in the mesoface pitch separation step,
A method for producing mesoface pitch, which comprises performing vacuum deaeration treatment at a temperature of about 310 to about 350° C. while stirring to remove light components contained in the pitch. (3) A heat treatment step in which a carbonaceous raw material is heat-treated to produce mesoface-containing pitch, and a mesoface pitch separation step in which the generated mesoface-containing pitch is separated into a mesoface pitch component and a non-mesoface pitch component to obtain mesoface pitch. In the method for producing mesoface pitch, the mesoface pitch obtained in the mesoface pitch separation step is subjected to non-oxidizing gas blowing and vacuum degassing treatment at a temperature of about 310 to about 350°C with stirring. A method for producing mesoface pitch, the method comprising: removing light components contained in the pitch.