JPS61241392A - Production of mesophase pitch - Google Patents

Abstract

PURPOSE:To obtain a homogeneous mesophase pitch having low softening point and suitable for the production of carbon fiber and molded carbon material having high strength and elastic modulus, by subjecting a mesophase pitch production raw material to hydrocracking pretreatment and carrying out the thermal decomposition polycondensation of the material. CONSTITUTION:After the hydrocracking pretreatment of a mesophase pitch production raw material, the material is heated (preferably at about 410-440 deg.C) to effect the thermal decomposition polycondensation until the mesophase pitch fraction in the polycondensate reaches about 20-80vol%. The polycondensation product is left at rest at about <=400 deg.C (preferably about 360-390 deg.C) to effect the growth and deposition of the mesophase pitch having higher density to the lower layer, which is separated from the upper layer fraction rich in non- mesophase pitch having lower density.

Description

[Detailed Description of the Invention] In response to technological advances in the aircraft industry, automobile industry, and various other technical fields, and also to the recent demands for energy saving and resource saving, we have developed a lightweight, high-strength, and high-elastic product. High-performance carbon fibers with high strength and high modulus of elasticity that constitute the material of composite materials, or molded carbon materials with high strength and high modulus of elasticity that are pressure-molded and used for various purposes. The present invention, which is strongly desired, is a material suitable for manufacturing such high-performance carbon fibers and molded carbon materials, that is, a material with a low softening point that can be stably formed by melt spinning at a sufficiently low temperature. , relates to a method for producing homogeneous mesophase pitch.

As used herein, "mesophase"
It is difficult to say that the meaning of the phrase ``is necessarily uniformly used in academic circles or in various technical documents.'' In this specification, ``mesophase'' refers to one of the pitch components, which solidifies near room temperature. When a cross-section of the pitch lump is polished and observed under crossed Nicols using a reflective polarizing microscope, brightness is observed when the sample or crossed Nicols is rotated. That is, it means a part that is optically anisotropic, and a part where no brilliance is observed, that is, a part that is optically isotropic, is called a "non-meso phase." In general, heavy hydrocarbons such as tar and pitch initially have a completely non-meso phase, but as the pyrolysis polycondensation reaction progresses, a spherical or amorphous meso phase is generated, and as they grow and coalesce, The meso phase grows larger.The meso phase is mainly composed of molecules with a chemical structure in which the planarity of polycyclic aromatic condensed rings is more developed than in the non-meso phase, and the planes are aggregated and aggregated in a stacked manner. Therefore, it is considered to be in a kind of liquid crystal state at the melting temperature.

Therefore, when extruded from a thin spinneret and spun, the carbon fibers made from the mesophase pitch exhibit a high modulus of elasticity because the molecular planes are aligned nearly parallel to the fiber axis direction. In addition, the mesophase is quantified by observing and photographing it under a polarizing microscope with crossed nicols and measuring the area ratio occupied by the optically anisotropic part.The results are expressed in volume %. A pitch that is 10% or less and is mostly composed of mesophase is referred to as a "mesophase pitch."

Regarding the pitch homogeneity, in the description of the present invention, the measurement result of the mesophase content mentioned above is about 90% to about 100% by volume.
microscopic observation of the pitch cross section reveals infusible particles (
Pitches whose particle size (IILm or more) cannot be detected in actual measurements exhibit good homogeneity in actual melt spinning, and are therefore referred to as substantially homogeneous mesophase pitches.

In addition, the "softening point" of pitch in the explanation of the present invention refers to the temperature at which pitch transitions between solid and liquid. It was measured at the peak temperature of absorption and release. This temperature agrees within a range of ±10°C with that measured by other methods (for example, ring-and-pole method, micro-melting point method, etc.) on pitch samples. In the present invention, "low softening point" means: Provision 3
It means a softening point in the range of 0°C to about 320°C.

Several manufacturing methods have been proposed to date for the production of mesophase pitch, which is necessary for the production of high-performance carbon fibers, etc. However, in all of these methods, ■ Raw materials are difficult to obtain industrially; ■ Requires a long reaction time or a complicated process; ■ The production cost is high; ■ The mesophase is
When the softening point approaches 00%, the softening point increases, making it difficult to spin; (2) If the softening point is suppressed, the material becomes non-uniform, making it difficult to spin. Let me explain in more detail.

The method described in Japanese Patent Publication No. 49-8634 is
Use inexpensive raw materials such as chrysene, anthracene, tetrabenzophenazine, etc. that are not available at OSE, or use high-temperature crude oil cracking tar after carbonization at 410°C.
Requires a complicated manufacturing process of filtering out infusible materials,
Moreover, a high spinning temperature of 400°C to 420°C was required. The method described in JP-A No. 50-118028 performs thermoheavy heating while stirring the raw materials, but looking at examples of the pitch manufacturing method, a simple process produces pitch with a high softening point, Obtaining a low softening point pitch required a long reaction time and filtration removal of infusible materials. Tokuko Showa 5
The method described in Publication No. 3-7533 involves polycondensation using a Lewis acid catalyst such as aluminum chloride.
This method is complicated and involves high operating costs, including removal of the catalyst and heat treatment steps before and after that. Japanese Patent Publication No. 50-896
The method described in Publication No. 35 involves thermal polycondensation using non-mesophase pitch as a raw material, under reduced pressure or by blowing an inert gas into the liquid phase to reduce the mesophase content to 40% to 90%.
It is a method of reacting until the
In Publication No. 25, the reaction is carried out by stirring during thermal polycondensation until the meso phase content becomes 50% to 65%, and in both of these methods, the meso phase of the pitch obtained is mixed with the quinoline solvent. This is a method of suppressing the softening point to the limit by leaving a considerable non-meso phase content, and there is a problem that the pitch is substantially non-uniform, resulting in poor spinnability. The method according to Japanese Patent Application Laid-open No. 54-55625 is described in
-89635 and JP-A No. 53-49125, i.e., using inert gas bubbling and stirring in combination, thermal decomposition polycondensation is carried out for a long time to completely convert 100% to meso phase. It causes the reaction to take place until
Although a homogeneous mesophase pitch can be obtained, there is a problem in that polycondensation progresses too much and the softening point and spinning temperature become high. Although the method shown in Japanese Patent Application Laid-Open No. 54-160427 can certainly provide a homogeneous mesophase pitch in actual purchase, it involves a complicated and expensive process called solvent extraction treatment, and moreover, it is not commonly used. has a high softening point (approximately 330
There is a problem in that the mesophase pitch becomes a pitch of 100°C (°C or higher).

As understood from the above explanation, according to the conventional technology,
Apart from methods using catalysts, it is difficult to industrially produce mesophase pitch that has a sufficiently low softening point, is homogeneous, and can be stably spun. That is, in the conventional technology, the mesophase content gradually increases by proceeding with thermal decomposition polycondensation of heavy hydrocarbons over a long period of time at a temperature of around 400°C in essentially one reaction step. However, the softening point of the pitch as a whole, and therefore the temperature suitable for melt spinning (spinning temperature), gradually rises, and when the reaction is stopped at an appropriate point at the spinning temperature, a mixture of meso and non-meso phases is formed. A homogeneous pitch is formed, and as a result good spinning cannot often be achieved. In order to improve this drawback, the reaction can be further continued at a lower temperature to obtain a homogeneous pitch with a mesophase pitch content of substantially 100%.
However, in that case, not only does it take a long time to react while controlling the temperature, but also it is difficult to obtain a good pitch with good reproducibility, and furthermore, the softening point is generally very high, making it difficult for industrial use. It is difficult to perform stable spinning, and as a result, it is not easy to produce carbon fibers with good performance.

As a result of various experiments, the present inventors have found that the cause of the various problems with the prior art is that even the meso phase formed initially in the pyrolysis polycondensation reactor is maintained at a high temperature until the end of the reaction. Therefore, it is thought that the molecules constituting the mesophase further undergo a polycondensation reaction in the mesophase pitch, and the molecular weight of the mesophase pitch becomes larger than necessary. It has been found that this problem can be solved by separating and extracting the mesophase pitch portion during the condensation reaction, and that by this method pitch with a mesophase content of 90% to 100% and a sufficiently low softening point can be obtained. Also, as a means of separating and extracting the meso phase part during the thermal reaction,
Attempts have been made to concentrate and extract the meso phase through a solvent extraction process using solvents such as n-hebutane, penzene, toluene, etc., and to directly separate the meso phase without using a solvent, but the former method has not been successful. Generally, it is difficult to control the softening point of mesophase pitch and the process is complicated, and the latter has been found to be superior.The present invention relates to a technique belonging to the latter.

As a result of various research experiments, the present inventors conducted thermal decomposition polycondensation of heavy hydrocarbons using a conventional method, and stopped the thermal reaction at the stage when the men phase was partially formed and dispersed in the form of small spheres. First, when the temperature of the reactant was lowered to a temperature range at which pyrolysis polycondensation was difficult to occur and the fluidity of the pitch as a liquid was sufficiently maintained, and the mixture was allowed to stand for a short period of time, mesophase spherules were formed. It was discovered that the reactants grow and coalesce in the reactor and settle down, and further coalesce at the bottom of the reactor, and the reactants are clearly separated into two layers, an upper layer and a lower layer, just as if water and oil were placed in a container. Ta. When the upper layer was extracted and examined, it was found to be a non-mesophase pitch part containing some small mesophase particles.

The lower layer was substantially 100% mesophase pitch, and in particular, the mesophase pitch was a pitch with a low softening point that was difficult to obtain with the prior art.

When this lower layer pitch was made into carbon fiber according to a conventional method, it was found that the so-called high-performance carbon fiber had extremely good spinnability and excellent performance.

As a result of further research on the above production method, the present inventors found that the method can use heavy oil, tar, or pitch containing heavy hydrocarbons as the raw material for mesohydration production, that is, as a starting material. It was. That is, various petroleum-based heavy oils, pyrolysis tar, catalytic cracking tar, steam cracking tar, asphalt, etc. can be used as starting materials, while heavy oil, tar, pitch, or coal obtained by carbonization of coal, etc. Heavy liquefied coal produced from a liquefaction process can also be used.

However, some heavy oils, tars, or pitches contain components with too high molecular weight or/and easily generate high molecular weight components in the thermal polycondensation process; It was found that in the next reaction step, the viscosity of the entire reaction system was increased, preventing the mesophase portion from coalescing and settling, and raising the softening point of the mesophase pitch produced.

The present inventors have discovered that such harmful components can be removed by pretreating the starting material by subjecting it to a hydrogenolysis reaction before bringing it into the pyrolysis polycondensation reaction.

In this way, the starting material pretreated by hydrogenolysis reaction before the thermal polycondensation step can be effectively used as a starting material in various other mesophase pitch production methods.

Therefore, the main object of the present invention is to pre-process raw materials for producing mesophase pitch by hydrogenolysis reaction, and then to perform thermal decomposition polycondensation to produce carbon fibers with a low softening point and further improved elastic modulus and strength. An object of the present invention is to provide a method for producing mesophase pitch that can be spun.

Another object of the present invention is that the present invention provides a simple and easy-to-use solution without requiring complicated steps such as hot filtration of infusible materials, solvent extraction, addition and removal of catalysts.
For example, it is an object of the present invention to provide a method for producing mesophase pitch in which the entire process can be completed in a short time of about 1 to 3 hours.

Another object of the invention is to provide a method for producing mesophase pitch consisting of about 90% to about 100% mesophase and having a low softening point (e.g. 260°C) and therefore a low optimum spinning temperature (e.g. 340°C). It is to provide.

Still another object of the present invention is to achieve the remarkable temperature (
The yarn can be spun at a temperature much lower than 400 degrees Celsius), and the pitch is uniform and the spinnability (frequency of yarn breakage, yarn thinness, variation in yarn diameter, etc.) is good, and the quality is stable. It is an object of the present invention to provide a method for producing homogeneous mesophase pitch that does not undergo deterioration and can produce carbon fiber products.

Another object of the present invention is that substantially no decomposition gas or infusible substances are generated during spinning, and therefore the spun pitch fibers contain few air bubbles or solid foreign substances.
An object of the present invention is to provide a method for producing mesophase pitch, thereby making it possible to produce carbon fiber products with high strength.

Furthermore, another object of the present invention is to provide a carbon fiber with a mesophase content of 100% and an excellent molecular orientation, which can produce product carbon fibers with a well-developed graphite structure crystal orientation in the fiber axis direction and a large elastic modulus. To provide a method for producing pitch close to %.

Still another object of the present invention is to provide a liquid crystalline pitch precipitation ripening and separation step after the pyrolysis polycondensation reaction step, so that the characteristics of the raw material are considerably changed or the operating conditions are changed in the previous step. It is an object of the present invention to provide a method for producing mesophase pitch which can stably and easily control the characteristic quality of the pitch in subsequent steps even if it changes to some extent.

Next, the method for producing mesophase pitch according to the present invention will be explained in detail.

To summarize, the present invention uses heavy oil, tar or pitch containing heavy hydrocarbons as a main component as a starting material, pre-treats the starting material by a hydrocracking reaction, and then processes the pre-treated starting material. is pyrolyzed and polycondensed to produce mesophase pitch. In the most preferred method for producing mesophase pitch, the starting material pretreated as described above is heated to perform pyrolytic polycondensation, so that the mesophase pitch portion in the residual pitch is about 20% to about 80%. After doing so.

In order to carry out the polycondensation at 400°C or less, particularly in a short period of time such as 5 minutes to 4 hours, the temperature is preferably about 350°C to about 400°C.
In this specification, "standing" means not stirring completely, or even if stirring is done, stirring is done very slowly. ), the mesophase pitch part with a high density is accumulated as one continuous phase in the lower layer while growing and ripening, and this is separated and taken out from the part containing a large amount of non-mesophase pitch, which is a lower density phase in the upper layer. Mesophase pitch is produced by:

The pitch produced by this method is a substantially homogeneous mesophase pitch containing about 90% to about 100% mesophase portion, and has an extremely low softening point (about 30°C to about 320°C).
℃), and therefore has a sufficiently low optimum spinning temperature (approximately 380℃).
~380°C).

As mentioned above, the present invention is characterized in that various high molecular weight heavy hydrocarbon oils, tars, or pitches can be used as starting materials. That is, as starting material 1
Various petroleum-based heavy oils, pyrolysis tar, catalytic cracking tar, steam cracking tar, asphalt, etc. can be used, while heavy oil, tar, pitch obtained by carbonization of coal, or produced from the coal liquefaction process Heavy liquefied coal can also be used. However, even if such a starting material contains solid particles such as carbon, it goes without saying that it is not preferable, so it is necessary to perform a filtration treatment in advance using a suitable filter. Also, if it contains too much light oil, it will make the subsequent process less economical, so it should be distilled under reduced pressure in advance so that the starting material has a boiling point of about 400°C or higher as its main component. is desirable.

In the present invention, first, a raw material that has been pretreated by a hydrogenolysis reaction is introduced into a pyrolysis polycondensation reaction tank, and a thermal reaction for producing a mesophase is performed. The pyrolytic polycondensation process, which will generally be at a temperature of about 380°C or higher, preferably from about 380°C to about 460°C, more preferably from about 410°C to about 440°C, converts heavy hydrocarbons into mesophase. This can be carried out using a known method of partially producing mesophase pitch, but it is known that the reaction occurs at temperatures above 350°C in the conventional method. Whereas the residence time required several tens of hours at a low temperature of about 380°C, this method can be carried out at a high temperature of 440°C with a short residence time of just one hour. This is also one of the features of the present invention. However, even in the present invention, performing the thermal decomposition polycondensation at a temperature of 460°C or higher is because the volatilization of unreacted raw materials increases, the softening point of the meso phase increases, and it becomes difficult to control the reaction. It is inappropriate.

In the pyrolysis polycondensation reaction step, stirring is performed for the purpose of preventing local heating, and the pyrolysis polycondensation reaction step is carried out under reduced pressure or under reduced pressure in order to quickly remove low molecular weight substances produced as a result of thermal decomposition. Although it is not necessary to inject and bubble active gas into the pitch, it is preferable to carry out the process while the gas is flowing.However, the pyrolysis polycondensation can be carried out under normal pressure or increased pressure without flowing an inert gas, and then under reduced pressure. It can also be achieved by removing low molecular weight substances by distillation or stripping treatment with an inert gas.

The pyrolysis polycondensation reaction process is a process in which the chemical structure of the pitch component molecules is changed using thermal decomposition and polycondensation of heavy hydrocarbons in the raw materials as the main reactions, and the general direction of the reaction is to cleave the paraffin chain structure. This is thought to be due to the development of a planar structure of polycyclic condensed aromatics due to dehydrogenation, ring closure, and polycondensation, and molecules with a more developed structure grow until they form a single phase through molecular association and aggregation. One of the main features of the present invention, which is considered to be a meso phase, is that this thermal decomposition polycondensation process is performed so that the meso phase portion is approximately 20 % to about 80%, preferably about 4
When the content is between 0% and about 70%, the mesophase portion is then transferred to an aging sedimentation separation step for aging, sedimentation and separation. As mentioned above, it is a feature of the present invention that the content of the mesophase portion is allowed over a fairly wide range. In order to obtain pitch in a good yield, the yield of pitch after the pyrolysis polycondensation reaction should be high and the mesophase content should be about 20%.
% to about 80% and a softening point of about 250°C or less is suitable.

If the mesophase portion in the pitch after the pyrolysis polycondensation reaction is less than 20%, the yield of homogeneous mesophase pitch in the next ripening and deposition step will be extremely small and of no practical value, and the pitch after the pyrolysis polycondensation reaction will be If the softening point of the pitch is higher than 250°C or the mesophase is larger than 80%, the two phases will not be separated sufficiently in the next step, and the softening point of the mesophase pitch produced will be too high. . In other words, if too little mesophase is produced in the pyrolysis polycondensation step, 1
The yield of mesophase pitch in the lower layer obtained in one separation operation is low, which worsens economic efficiency, but on the other hand, if too much mesophase is generated and the process is moved to the next step, the mesophase pitch yield will certainly decrease. However, the boundary between the upper layer and the lower layer becomes unclear, resulting in a form containing a non-meso phase in the meso phase, and the softening point of the produced meso phase pitch becomes high, making it unsuitable for the purpose of the present invention. .

Regarding the method of transferring the pitch containing a moderate amount of meso phase prepared as described above to the next step, that is, the ripening sedimentation/separation step of the meso phase, a separate separate chamber provided exclusively for the ripening sedimentation/separation step is used. The pitch may be transferred to a reaction tank, or if the pitch is produced completely batchwise, the same reaction tank as that in which the pyrolysis polycondensation was carried out may be used to carry out the ripening sedimentation e-separation step. In the latter case, the pitch transfer operation can be omitted.

It is a major feature of the present invention to have the aging sedimentation/separation step as described above, but it is preferable to use a temperature in this step that is slightly lower than that of the preceding pyrolysis polycondensation step. There is little gas generation, and polycondensation no longer progresses.

The temperature is low enough that the molecular weight of mesophase molecules that have already been formed is unlikely to increase, and the entire system is liquid, maintaining a viscosity that allows the mesophase to grow, coalesce, and settle quickly. It is necessary to choose a sufficiently high temperature. Such a temperature range varies depending on the raw materials and the conditions of the thermal decomposition polycondensation in the previous step, but generally has a range of several lθ°C and can be controlled with sufficient margin. That is, the temperature range in this step is approximately 350° C. to approximately 400° C., assuming that the required time for this step is 5 minutes to 4 hours, which is considered to be industrially preferable. 360℃~about 390℃
is within the range of Maintaining it in this temperature range means
By cooling the pitch, which has become hot in the previous step, and keeping it warm, there is no need to add or control a particularly large amount of heat, which is easy.

In the aging precipitation reaction, when the required treatment time for the aging precipitation step is 5 minutes to 4 hours, which is considered to be industrially preferable as mentioned above, clear separation is generally not observed at temperatures below 350°C. However, it is possible to accomplish the process at temperatures below 350° C. if it is acceptable to spend a longer time, for example 15 hours or more. On the other hand, if the temperature exceeds 400°C, the mesophase pitch tends to denature during deposition and the softening point tends to increase, which is not suitable.

In terms of wood quality, the aging and sedimentation process can achieve its purpose by allowing the liquid phase of the pitch to stand completely still without stirring, but in the early stages of the process, it is necessary to homogenize the temperature distribution and component distribution of the entire system. Stirring is preferably carried out for the purpose of stirring, and very slow stirring can also be carried out throughout.

The actual time required for this step can be freely selected from 5 minutes to 4 hours at an appropriate temperature range of about 360°C to about 390°C, but if the time is long enough, the separated mesophase 100%, but the softening point tends to be high. On the other hand, if the time is short, the softening point is low, but a substance containing a large amount of non-meso phase tends to be separated. In the process, the mesophase that has already been generated in the previous step is generally dispersed in a spherical shape with a diameter of 200 JLm or less (Figure 1), but in this process, it gradually grows and coalesces, depositing at the bottom, and further forming at the bottom. They coalesce into a large lump (Figure 2), which then coalesces further,
An even larger liquid layer forms (Figure 3), and finally a lower layer separates from the upper non-meso phase (including some small meso phase) through a clear planar interface (Fig. 3). 4
(Fig. 5), when this state is reached, the valve attached to the bottom of the maturation sedimentation tank is opened, the lower layer is gently drained out, and the target pitch product (Fig. 5) is recovered. In this case, it is technically possible to extract and separate the upper layer first. Furthermore, the fact that the boundary between the upper layer and the lower layer has been reached during the extraction operation can be easily detected from the relationship between the differential pressure in the extraction pipe and the flow rate, since the viscosities of the two layers are considerably different. In addition, in this process, the two layers are not necessarily completely 100% mesophase pitch, but if the purpose is to obtain a substantially homogeneous mesophase pitch containing 90% or more mesophase, the two layers can be clearly separated. Although the previous spherical mesophase has not yet fully coalesced in the lower layer, the lower layer may be extracted at a stage when it is almost sedimented and separated (FIG. 2 or 3).

In the aging sedimentation/separation step, the upper layer portion formed mainly of a non-meso phase can be returned to the aging sedimentation/separation step or the preceding pyrolysis polycondensation step for use. In other words, after separating the lower layer, if the upper layer, which is mainly composed of non-meso phase and contains only a small amount of microspherical (104 m to 20 pLm diameter) meso phase, is subjected to the sedimentation separation process again, a spherical meso phase is obtained. was found to grow again, settle and coalesce, forming a mesophase that was deposited in the lower layer again, although the yield was slightly lower than the first time. Furthermore, it was observed that the mesophase pitch produced in the second run had a lower softening point than the mesophase pitch produced in the first run. This means that the ripening-sedimentation-separation step does not simply result in sedimentation and separation of the meso phase generated in the previous pyrolysis polycondensation step, but rather that the pitch component molecules that can become the meso phase are dissolved in the non-meso phase. to meet,
Or incorporated into the mesophase droplets that have already been generated.

This shows that it has the effect of gradually growing the mesophase to a larger size, and furthermore, it has the effect of coalescing the dispersed mesophases and ripening them into a large mesophase that tends to settle.

In addition, when the upper layer portion mainly composed of the non-meso phase is returned to the previous pyrolysis polycondensation step, the meso phase content increases in a short time, and meso phase spherulites with a large diameter are also formed. When this is transferred to the aging sedimentation φ separation step and the lower layer is separated, a substantially homogeneous mesophase pitch with a low softening point is obtained in a high yield.

Therefore, the present invention encompasses a method for producing a substantially homogeneous low-softening-point mesophase pitch in a high yield by recycling the pitch mainly composed of the non-mesophase in the upper layer in the aged sedimentation separation process. .

The pitch produced by the method of the present invention contains about 90% to about 100% mesophase portion, and is a substantially homogeneous mesophase pitch, but has an extremely low softening point (approximately 30°C to about 320°C), and thus a sufficiently low melt-spinning compatible temperature (about 90°C to about 380°C).
). It has also been found that when carbon fibers are prepared using this pitch according to conventional methods, extremely high-performance carbon fibers can be obtained with good stability. That is,
As can be seen in the examples described below, the substantially homogeneous mesophase pitch (containing about 90% to about 100% mesophase) with a low softening point obtained by the method according to the present invention is below about 380°C. Ordinary melt spinning is easy at a temperature of .

The frequency of yarn breakage is low, the yarn can be taken up at high speed, and fibers with an average diameter of 5 pm to 12 ILm can be obtained.

Next, the present invention will be explained based on examples.

Example 1 Tar obtained by distilling residual oil obtained by steam cracking of naphtha under reduced pressure to 450° C. in terms of normal pressure was used as a raw material. The characteristic values of this product are carbon content 92.8wt%, hydrogen content 7.0wt%, and specific gravity 1.12. Quinoline solubility θ%
It was a viscous liquid at room temperature with a number average molecular weight of 650 and a maximum molecular weight of 12,000.

400g of this raw material tar and 5wt% Nickelsha molybdenum catalyst based on the raw material tar are contained in the stirring device MIJ
Place it in the autoclave of I and stir it thoroughly.
After increasing the temperature to 370℃ at a rate of ℃/min, 370℃
The hydrogen cracking reaction was carried out for 2 hours at a hydrogen pressure of 150 kg/c rn"・G. Next, the hydrogen cracking product was converted to normal pressure and vacuum distilled to 415°C to remove light oil. A treated tar was obtained.

The tar subjected to this pretreatment has a carbon content of 92.1
wt%, hydrogen content 7.8%, specific gravity 1°07, quinoline solubility θ%, number average molecular weight 450, maximum molecular weight 2800
It was a viscous liquid at room temperature. 42% of raw material tar
The yield was .

This raw material tar 1000100O was placed in a reactor with an internal volume of 45M, and was heated under atmospheric pressure and a nitrogen gas flow with thorough stirring.
Heat treated at 30℃ for 2 hours, softening point 224℃, specific gravity 1.3
1. When observed under a polarizing microscope with a viscosity of 11 poises (300°C), a number average molecular weight of 950, a maximum molecular weight of 13°000, and a quinoline solubility of 15 wt%, a small mesophase with a diameter of 2001 Lm or less and an almost entirely spherical shape was observed in the isotropic matrix. A pitch containing about 50% of spheres in terms of area ratio is 1% to the raw material tar.
Obtained with a yield of 768 wt%.

This pitch was placed in a small aluminum container with an inner diameter of 3 cm and a length of 10 cm, and kept in a static state without stirring at 380°C in a nitrogen atmosphere for 2 hours. After cooling and solidifying, the pitch was ground vertically in the metal container. When the cross-section was observed under a polarized light microscope, the pitch was clearly separated into two layers, an upper layer and a lower layer, and the pitch of the upper layer was approximately 20 mm in diameter, consisting of true spherical mesophase spherules with a diameter of about 20 #Lm or less. The majority including 1O% is non-meso phase,
Softening point: 198°C, specific gravity: 1-27. Quinoline dissolved content 4wt
%Met. The pitch of the lower layer is 100 with a large flow pattern.
% meso phase, the softening point was 272°C, the specific gravity was 1.33, and the quinolinated content was 38 wt%. The yield of pitch was 6°, 5 wt % for the non-meso phase pitch in the upper layer, and 39.5 wt % for the 100% meso phase pitch in the lower layer, based on the amount of filling.

The substantially homogeneous mesophase pitch thus obtained was spun using a spinning machine having a nozzle with a diameter of 0.5 mm at a spinning temperature of 340° C. and under a nitrogen pressure of 200 mm Hg or less. This pitch fiber was subjected to infusibility treatment at 240°C for 30 minutes in an oxygen atmosphere, then heated to 1,500°C at a rate of 30°C/min in an inert gas, and then left to cool to obtain carbon li1. .

The mesophase pitch according to the present invention has good spinnability.

In addition, the amount of modifying acid in the pitch during spinning is small, and the tensile strength is 2.
Carbon fibers with a thread diameter of 10 ILm and a tensile modulus of 7X109Pa and a tensile modulus of 2.6XlOPa were obtained.

Comparative Example 1 Tar obtained by distilling residual oil obtained by steam cracking of naphtha under reduced pressure to 450° C. in terms of normal pressure was used as a raw material.

The characteristics of the raw material are: carbon content 92.8 wt%, hydrogen content 7.0 wt%, specific gravity 1.12, quinoline soluble content 0%, number average molecular weight 650, maximum molecular weight 112,000, and is a viscous liquid at room temperature. there were. This raw material tar, 1,000 gr, was placed in a reactor with an internal volume of 1.45 kg, and heat-treated at 430°C for 2 hours with sufficient stirring under a nitrogen gas flow at normal pressure.The softening point was 345°C, the specific gravity was 29, and the viscosity was 450 poises
(380℃), number average molecular weight 2300, maximum molecular weight 4
When observed with a polarized light microscope at 8°000 and a quinoline solubility of 17 wt%, the raw tar contained pitch containing about 30% by area of mesophase spherules with a diameter of 50 pm or less and an almost entirely spherical shape in an isotropic matrix. The yield was 39 wt%.

This pitch was placed in a small aluminum vessel-shaped container with an inner diameter of 3 cm and a length of 10 cm, and kept in a static state without stirring for 2 hours at 380" O in a nitrogen atmosphere. Then, after cooling and solidifying, the pitch was ground vertically in the container. , when the cross section was observed with a polarizing microscope,
It could not be clearly separated into two layers.

The pitch was heated at 380°C to 41°C in the same spinning vessel as in Example 1.
Although spinning was carried out at a spinning speed of 0° C., yarn breakage was severe and spinning was impossible.

[Brief explanation of the drawing]

FIGS. 1 to 5 are micrographs of polished pitch cross-sections taken using a single-reflection polarizing microscope at a magnification of 50 times in crossed nicols. Figure 1 shows the pitch in which an appropriate amount of spherical mesophase is dispersed through only the pyrolysis polycondensation process, and Figure 2 shows the pitch of Figure 1 at 38 cm.
Figure 3 shows the bottom part when the pitch in Figure 1 is left at 380°C for 30 minutes,
FIG. 4 shows the two-layer interface when the pitch shown in FIG. 1 was left at 380° C. for 2 hours, and FIG. 5 shows the lower layer pitch extracted in Example 2. Agent Patent Attorney Tachibana Kura Ai Ku Ku Ku Ku C Tsujo Ku - Written amendment (method) % formula % Display of the case 1985 Patent Application No. 292351, Name of the invention Case of a person amending the manufacturing method of mesophase pitch Relationship with Patent applicant address No. 1, Tsuhashi-chome, Chiyoda-ku, Tokyo
Name: Suzue Building, Toa Fuel Industry Co., Ltd. (Telephone: 459-8309) April 22, 1986 (shipment date) (-) The "Description" is amended as follows. Delete the "Brief description of drawing" column. That is, the text from page 31, line 18 to page 32, line 1θ is deleted. (d) “Drawings” shall be amended as follows. Delete all “Figure 5” from “Figure 1”.

Claims (1)

[Scope of Claims] 1) The raw material for producing mesophase pitch is pretreated by hydrogenolysis reaction, and the pretreated raw material for producing mesophase pitch is subjected to pyrolysis polycondensation. A method for producing mesophase pitch. 2) The raw material for producing meso-phase pitch is pre-treated by hydrogenolysis reaction, the pre-treated raw material for producing meso-phase pitch is heated and subjected to pyrolysis polycondensation, and the meso-phase pitch portion in the polycondensate is After adjusting the content of the polycondensate to be about 20% to about 80% by volume, the polycondensate is left to stand while being maintained at about 400°C or less, and a mesophase pitch portion with a high density is grown and aged in the lower layer. A method for producing mesophase pitch, the method comprising: collecting the mesophase pitch, and separating and extracting the mesolayer pitch portion from the pitch portion in which the non-mesophase with a low density in the upper layer occupies the majority. 3) The method for producing mesophase pitch according to claim 2, wherein the raw material for producing mesophase pitch contains as a main component a hydrocarbon having a boiling point of about 400° C. or higher. 4) Pyrolytic polycondensation of the raw material for producing mesophase pitch at a temperature in the range of about 380°C to about 460°C.
A method for producing mesophase pitch as described in . 5) Pyrolytic polycondensation of the raw material for producing mesophase pitch at a temperature in the range of about 410°C to about 440°C.
A method for producing mesophase pitch as described in . 6) The polycondensate is maintained at a temperature in the range of about 350° C. to about 400° C. and allowed to stand for a required period of time to grow and mature the mesophase pitch portion with a high density in the lower layer, as claimed in claim 2. A method for producing the mesophase pitch described. 7) Claim 6, wherein the polycondensate is aged and deposited while being maintained at a temperature in the range of about 360°C to about 390°C.
A method for producing mesophase pitch as described in . 8) A method for producing a mesophase pitch according to claim 2, which contains a mesophase pitch portion of about 90% to about 100% by volume and has a softening point of about 320° C. or less. 9) The mesophase pitch portion in the polycondensate has a volume content of approximately 4
3. The method for producing mesophase pitch according to claim 2, wherein the raw material for producing mesophase pitch is subjected to pyrolysis polycondensation so that the concentration is 0% to about 70%. 10) The method for producing mesophase pitch according to claim 2, which comprises recycling the upper layer portion mainly consisting of a non-mesophase pitch portion to a pyrolysis polycondensation step or an aging sedimentation separation step.