JPS6251997B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for modifying heavy bituminous substances such as pitches for producing high-grade carbon materials such as carbon fibers and needle coke.

Prior art Carbon products such as carbon fiber, needle coke, or artificial graphite electrodes using them have crystal structures similar to graphite, and have excellent mechanical and electrical properties such as Young's modulus and electrical conductivity. Express.

Generally, in order to produce carbon products, heavy bituminous substances are first made into pitches for carbon products by adjusting their softening point, molecular weight, etc. through methods such as heat treatment and extraction.
This is usually formed into a desired shape, such as a fiber, and then carbonized or graphitized.

In the process of manufacturing these carbon products using heavy bituminous material as a raw material, generally speaking, when the heavy bituminous material is heated, the isotropic liquid becomes optically anisotropic liquid crystalline so-called mesophase spherulites. occurs, and as it grows, coalesces, and deforms, the amount of mesophase increases, and at 500 to 600°C it passes through a state of accumulation of graphite-like microcrystallite with a stack of carbon hexagonal networks, and is then treated at higher temperatures. As time passes, the net surface develops and grows into a giant crystal. In order to develop the crystals of the structural components that make up these carbon products so that they approach a graphite structure,
For carbon products, the molecules in the pitch state must have a high degree of optical uniaxial orientation.

For example, in the production of pitch-based carbon fibers, whether the molecules in the carbon fiber pitch can be highly oriented in the fiber axis direction during the melt-spinning process greatly controls the degree of growth and orientation of carbon fiber crystals after firing. do.
Therefore, it can be said that the required pitch for carbon fibers is a mesophase pitch in which molecular groups are regularly oriented and has fluidity. Such a requirement is a common requirement for raw materials for artificial graphitic carbon products.

By the way, the regularity and orientation of the molecular groups in pitches for carbon products generally become stronger as the aromatic planar molecules become larger and as the content of mesophase increases, but usually the softening point increases accordingly. ,
Fluidity decreases and processability deteriorates. In the production of carbon fiber, the content of mesophace is 100
%, it becomes difficult to flow during the spinning process, and when the spinning temperature is increased to improve fluidity, problems such as partial decomposition of the pitch arise.

Therefore, there is a need for a method for producing a pitch for carbon products that is a mesophase pitch and has a low softening point, in other words, a pitch that has a high mesophase content at the same softening point. Such an excellent mesophase with high fluidity is such that even after the mesophase is generated as spherulites during the heat treatment process of heavy bituminous material, the mesophase spheres easily coalesce with each other to form a large domain coalesced structure or mesophase. is likely to form a continuous phase. Furthermore, as one of the methods for evaluating the characteristics of these mesophase pitches, the degree of solubility of mesophase pitches in solvents such as quinoline is also used as an index for evaluating pitches for carbon products.

A typical method for manufacturing mesophase pitch is to heat isotropic pitch at 400°C for 17 hours, as described in Japanese Patent Publication No. 1810/1983, which results in approximately 50% A mesophase is formed. However, almost all of the mesophace obtained by this method is insoluble in quinoline or pyridine, and as a result, the mesophace pitch has a high softening point, making spinning difficult.

On the other hand, mesophace pitch containing quinoline-soluble mesophace has the advantage of being easy to spin due to its low softening point, and has recently attracted attention as a suitable raw material for high-performance carbon fibers, and research on its production method is underway. is being actively carried out. Prior art related to methods for producing mesophace pitch containing quinoline-soluble mesophace include the following.

In JP-A-54-160427, quinoline-soluble mesophase is obtained by extracting isotropic pitch with a solvent and heating the insoluble portion to 230 to 400°C. The inventor calls this neomesophase, and the solvent-insoluble fraction before heating is called the neomesophace production fraction (NMF fraction). Furthermore, in a series of patents, he proposed increasing the amount of NMF fraction and improving the NMF fraction separation method. (Unexamined Japanese Patent Publication No. 55-58287
No., JP-A-55-130809, JP-A-55-144087,
JP-A-56-2388, JP-A-56-109807, JP-A-Sho
56-167788 and JP-A-57-2393)) In JP-A-54-55625, isotropic pitch is
A mesophase pitch containing pyridine-soluble mesophase was obtained by heat treatment at 380-430°C with stirring and passing an inert gas. The heating time for this method is 2 to 60 hours.

In JP-A-56-57881, mesophase pitch containing pyridine-soluble mesophase is obtained by subjecting pitch to physical operations such as solvent extraction.

In JP-A-56-101915, a mesophace pitch containing pyridine-soluble mesophace was produced by heat-treating a pitch precursor such as ethylene tar at 400 to 550°C under pressure and then heat-treating it under atmospheric pressure through an inert gas. I am getting . The heat treatment conditions in this case are similar to those described in JP-A-54-55625, which has the problem that the heating time is long.

JP-A No. 18421/1984 discloses that after treating pithu with tetrahydroquinoline or quinoline and hydrogen in the presence of a catalyst at 340 to 450°C, it is treated at a temperature of 450°C or higher under a pressure of 50 mmHg or less for up to 60 minutes. It is stated that an isotropic pitch called Primesophace can be obtained by heat treatment, and that high-performance carbon fiber can be obtained using this.

JP-A-58-154792 discloses a method of heat-treating a specific pitch to obtain mesophase pitch, and JP-A-55-15769 discloses a method of hydrogen-treating petroleum residue oil and then heat-treating it under pressure. high-purity petroleum pitch is obtained.

As mentioned above, the known techniques require special processing such as extraction, use a large amount of special gas, have complicated processes, take a long processing time, and require a large amount of raw materials to produce mesophace pitch. There were some problems, such as being special.

Also, JP-A-58-185612, JP-A-58-
In Publication No. 185613, mesophasic pitch was obtained by reacting a polynuclear aromatic hydrocarbon with a mixture of AlCl ₃ and an organic amine salt, but as a result of using a special reagent such as AlCl ₃ , this was removed. special means are needed to do so.

As a result of various studies on the production of high-performance mesophace pitch for carbon products as an alternative to the above-mentioned known technology, the present inventors added alcohol to heavy bituminous materials such as pitch and caused a thermal reaction. Later, it was discovered that a mesophasic pitch suitable for high-performance carbon products could be obtained by further heat treatment, and the present invention was achieved.

In the present invention, the mesophase refers to a structure exhibiting optical anisotropy that can be determined by polishing the surface of a cooled and solidified pitch and observing it using a reflective polarization microscope. Furthermore, the mesophase content in the mesophase pitch refers to the proportion of anisotropic structure observed in this way. As described in "Carbon", No. 116, P35 (1984), mesophase has "molecular groups that are regularly oriented, but has fluidity, and is capable of reversible phases such as melting, reprecipitation, etc." It is a liquid crystal state that can change.

Therefore, it is possible that part or all of the mesophase pitch transforms into an isotropic structure at high temperatures, but it is very difficult to observe the structure at high temperatures, and it is not known clearly.

The relationship between conventional alcohols and heavy bituminous substances is
It has never been considered other than as an extractant for removing light components unsuitable as raw materials for carbon materials from heavy bituminous substances. The main part or most of heavy bituminous substances are insoluble in alcohols, and are completely unsuitable as processing agents for heavy bituminous substances, which are raw materials for carbon materials. In addition, when manufacturing carbon products using these raw materials, O, S, etc. in the raw materials are generally removed during the process of obtaining the product through the carbonization process.
It is known that it inhibits graphitization, and reaction with alcohols may give O, so it is completely unthinkable in common sense as a means of producing raw materials for carbon products.

Purpose/Structure of the Invention Contrary to such common sense, the inventors of the present invention have repeatedly studied in detail the thermal reactions between heavy bituminous substances and various compounds, and as a result, the inventors of the present invention have conducted a thermal reaction between heavy bituminous substances and alcohols. They have discovered that by heat-treating the material until it becomes mesophase, pitch for carbon products with very different and superior properties can be obtained compared to when heavy bituminous materials are heat-treated alone.

That is, the present invention is a method for producing pitch for carbon products, which comprises adding alcohol to heavy bituminous material, causing a thermal reaction at a temperature of 250°C or higher, and then further heat-treating until mesophase is produced.

The heavy bituminous substances referred to in the present invention include coal tar,
It refers to heavy coal liquefied oil, petroleum distillation residue oil, petroleum cracking residue oil, and the pitch fraction produced from them, but in terms of the yield of pitch for carbon products, it is preferable to cut the light fraction, the so-called pitch cut. .

The alcohols referred to in the present invention include methanol,
Saturated alcohols such as ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, unsaturated alcohols such as allyl alcohol, halogeno alcohols such as ethylene chlorohydrin, polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, glycerin, etc. It is a compound having an alcoholic hydroxyl group, such as alcohol or amino alcohol such as ethanolamine.

The thermal reaction between heavy bituminous substances and alcohols is
This is carried out by heating at 250°C or higher, preferably between 300°C and 550°C for 5 minutes or more. No reaction occurs at temperatures below 250°C. Moreover, if the temperature becomes high, the coking reaction of heavy bituminous materials becomes intense, which is not preferable.

The thermal reaction requires that the alcohol be confined, and is therefore carried out under pressure above the autogenous pressure. This pressure often exceeds the critical pressure if the alcohol used has a low boiling point.

The effect of thermal reaction can be understood as follows. That is, after carrying out a thermal reaction, the heavy bituminous material is then heat treated to produce mesophase in the heavy bituminous material. As the heat treatment is intensified, the amount of mesophace increases and eventually cokes. During this period, as the content of mesophace increases, the softening point of mesophace pitch increases, but as shown in Figure 1, the softening point of mesophace pitch obtained from heavy bituminous material thermally reacted with alcohol is the same. The mesophace content in the product thermally reacted with alcohol is several degrees Celsius to several tens of degrees Celsius lower.

In addition, when we observed the structure using a reflective polarizing microscope of mesophase pitches in which mesophases formed a continuous phase with and without thermal reaction with alcohols, we found that the mesophase pitches with and without thermal reaction with alcohols were observed using a reflective polarizing microscope. Mesophase obtained from heavy bituminous materials has larger domains when compared with the same mesophase content.
In other words, it can be seen that there are few lamination defects.

From the above, mesophace produced by further heat-treating heavy bituminous substances that have been thermally reacted with alcohols has higher fluidity than mesophace produced by heat-treating heavy bituminous substances that have not been thermally reacted with alcohols. I understand that.

The mechanism of thermal reaction between heavy bituminous substances and alcohols is thought to be as follows. Figure 2 shows coal tar pitch and isopropanol in a weight ratio of 1:1.
Nuclear magnetic resonance (NMR) of the light components distilled off from the reactants after a thermal reaction at 350℃ for 90 minutes under autogenous pressure.
It is a spectrum. A peak unique to acetone was observed at a δ value of 2.1 ppm, and it was calculated that about 4% acetone was present relative to isopropanol. Furthermore, Figures 3 and 4 show the infrared absorption (IR) spectra of light components obtained by thermally reacting normal butanol, secondary butanol, and coal tar pitch, respectively, in comparison with the alcohol used as a raw material. However, the raw material normal butanol and secondary butanol shown in B in the diagram
As is clear from comparison with the IR spectrum, carbonyl peaks that do not exist in the raw material appear in the thermally reacted product A at around 1640 cm ^-1 and 1700 cm ^-1 .

Therefore, it is conceivable that the hydrogen in the alcohol migrates to the coal tar pitch and transforms itself into a carbonyl compound, but as can be seen in the above example of isopropanol, the carbonyl produced is only a portion of the added alcohol, and a considerable amount is generated. remains as alcohol, and it is possible that the heating reaction of pitch is unique due to the presence of alcohol, and the details cannot be clearly stated yet.

The reduction in the softening point of mesophasic pitch obtained by thermally reacting heavy bituminous materials with alcohols and then heat-treating them varies depending on the addition ratio of alcohols.

Figure 1 shows that coal tar pitch, which has undergone a thermal reaction by varying the addition ratio of alcohol, is heat-treated by varying the treatment temperature, treatment time, and degree of vacuum to produce mesophase pitches with different mesophase contents. The relationship between the softening point of mesophace pitch and the content of mesophace was determined, and the softening point was compared when the mesophace content was 70%, and it was found that even with a small amount of alcohol added, the softening point was quite high. It can be seen that there is a decrease in

The effect of lowering the softening point of mesophasic pitch is noticeable when producing carbon fibers from pitch. Pitch-based carbon fibers are produced by first melt-spinning pitch, and usually pitch is spun at a temperature 20 to 60°C higher than its softening point. When the spinning temperature becomes high, some of the pitches undergo thermal decomposition, producing gas and causing coking. Therefore, there is naturally an upper limit to the spinning temperature, which is 380 to 400℃.
That's about it. On the other hand, in order for carbon fiber produced from pitch to exhibit excellent physical properties such as elastic modulus, it is said that the content of mesophase in the spinning pitch must be high, and the content should be 40% or more, preferably 60%. The above is desirable.

According to the present invention, even if heavy bituminous materials are heat-treated until the mesophace content becomes high, the mesophase content can be increased by several degrees compared to the case where no thermal reaction with alcohols is carried out.
Being able to lower the softening point by several tens of degrees makes it possible to spin carbon fiber pitches with a high mesophace content, which is extremely advantageous for producing high-quality carbon fibers. In order to produce such an effect, the amount of alcohol added is desirably 1 wt% or more, preferably 2 wt% or more, based on the heavy bituminous material.
Further, the thermal reaction is preferably carried out under pressure for 5 minutes or more.

In the thermal reaction between heavy bituminous substances and alcohols, the use of a catalyst further accelerates the reaction.
As the catalyst, basic substances such as caustic alkali, alkali carbonate, and tar bases are effective. By using a catalyst, the temperature of the thermal reaction can be lowered, the reaction time can be shortened, and the ratio of alcohol added can be reduced in order to obtain the same effect.

For example, to 100 parts by weight of coal tar pitch, 100 parts by weight of isopropanol is added, and then 1 part by weight of caustic potassium is added as a catalyst, and heated at 320℃ and 90% by weight.
After the reaction, the light components were distilled off, and the NMR spectrum was measured to compare the amount of acetone produced. It was found that the amount of acetone produced was about 3
Double the amount of acetone was produced, and the thermal reaction was carried out under the same conditions as the heat-treated pitch without using a catalyst.
Compared to heat-treated pitch, the softening point was about 20°C lower when a catalyst was used.

After thermally reacting heavy bituminous substances and alcohols, heat treatment is performed to obtain mesophase pitch with a mesophase content of 40% or more. A known method can be used for the heat treatment to form a mesophase. For example, heating to 350℃~500℃ under reduced pressure, while blowing with inert gas.
A method of heating at 350-500℃, a method of heating at around normal pressure and then performing vacuum distillation or blowing with inert gas to remove light components and increase the softening point and mesophase content, etc. There is. In either method, those skilled in the art can easily determine experimentally the conditions that provide a pitch for carbon products with the required mesophase content, such as heat treatment temperature, heat treatment time, degree of reduced pressure, or amount of inert gas. Can be done. Typically, a mesophasic pitch can be obtained by heat treatment at a temperature of 400° C. or higher for 0 to 60 minutes and a pressure of 50 Torr or lower.

The heat treatment for mesophace formation after the thermal reaction is
This is done by removing unreacted alcohols and generated aldehydes and ketones. There are methods for this, such as distillation, static separation, and centrifugation, but heat treatment usually
Since it is carried out at high temperature and near normal pressure or under reduced pressure, or by inert gas blowing, etc., it can be naturally distilled without any prior separation, so it can be used as it is for mesophase formation following the thermal reaction. You may proceed to heat treatment. Alternatively, since alcohols have poor compatibility with heavy bituminous materials, it is convenient to separate and remove the alcohols, since phase separation occurs simply by allowing the reaction system to stand still after the thermal reaction.

Quinoline insoluble substances, etc. in heavy bituminous materials generally reduce the quality of the produced pitch for carbon products. Particularly in the case of carbon fibers, this is undesirable as it may cause clogging of the nozzle during the spinning process. In the present invention, it is also necessary to remove quinoline-insoluble substances from the heavy bituminous raw materials depending on the application, but this may be done either before or after the thermal reaction with the alcohol. . For removal, known methods such as solvent extraction using quinoline or various solvents, melt filtration, centrifugation, etc. can be used.

Using the mesophase pitch of the present invention, high-grade carbon products such as carbon fibers and needle coke can be produced by known methods.

For example, carbon fiber is produced by melt-spinning mesophase pitch at a temperature 20 to 60 degrees Celsius higher than its softening point, then oxidizing it in an atmosphere of air or oxygen, and then spinning it in an inert atmosphere for 1000 to 60 degrees Celsius. 2000
℃ or by subsequent heating to 2000°C or more and 3000°C, carbon fibers or graphitized fibers can be obtained.

The mesophace pitch of the present invention has a low softening point in spite of its high mesophace content, so it can be spun at a low temperature during melt spinning, without causing coking, and stably producing high-quality carbon fibers. can be obtained easily.

Examples are shown below, in which the mesophace content is based on area, and unless otherwise specified, parts and percentages are based on weight.

Example 1 100 parts of coal tar pitch with a softening point of 82°C, 11% toluene-insoluble content, 0% quinoline-insoluble content, and 50 parts of isopropyl alcohol were placed in an autoclave, and the autoclave was sealed after replacing the air inside with N ₂ gas. ,
A thermal reaction was carried out at 320°C for 90 minutes. The pressure at this time was 80Kg/cm ² G.

After the thermal reaction was completed, the mixture was cooled and the supernatant liquid containing unreacted isopropyl alcohol was separated by decantation.

This pitch was heat-treated at 450° C. for 15 minutes at 4 Torr to obtain mesophase pitch. A reflected polarized light micrograph of this mesophase pitch is shown in FIG.
It can be seen that the mesophase domain is larger compared to the comparative example shown in FIG.

Comparative Example 1 The same coal tar pitch used in Example 1 was not subjected to a thermal reaction, but other conditions were the same as in Example 1, and the time was varied to obtain various mesophase pitches. FIG. 6 is a reflected polarized light micrograph of a sample having the same mesophase content as FIG. 5.

Example 2 A coal tar soft pitch with a softening point of 36°C, a toluene insoluble content of 11%, and a quinoline insoluble content of 5% was heated and filtered to obtain a pitch with a softening point of 36°C, a TI of 11%, and traces of QI. 100 parts by weight of this pitch and 200 parts by weight of isopropyl alcohol were placed in an autoclave, the air inside was replaced with _N2 gas, and the autoclave was sealed.
Thermal reaction was carried out at ℃ for 90 minutes. The pressure at this time is
It was 131Kg/cm ² G.

After the thermal reaction was completed, the light oil supernatant containing unreacted isopropyl alcohol was separated by decantation.

This pitch was heat-treated at 470° C. for 15 minutes at 10 Torr in an N ₂ gas atmosphere to obtain a mesophase pitch.

When the surface of this mesophasic pitch was polished and observed with a reflective polarizing microscope, it was as shown in FIG. Comparing the comparative example in FIG. 8, it can be seen that the mesophase domain is larger.

Comparative Example 2 Pitch obtained from the same coal tar soft pitch as that used in Example 2 was heat-filtered in the same manner as in Example 2, and heated at 470°C for 15 minutes at 10 Torr and N without performing a thermal reaction. ₂ When heat treated under atmosphere,
Caused caulking. Therefore, the heat treatment temperature was set to 450℃.
Various mesophase pitches were obtained by changing the heat treatment time under 10 Torr and N ₂ atmosphere, and the surfaces were polished and observed with a reflective polarization microscope. FIG. 8 shows one example of this, which contains approximately the same amount of mesophace as the mesophace pitch obtained in Example 2.

Example 3 100 parts by weight of petroleum-based pitch with a softening point of 120°C, 5.5% benzene insoluble content, traces of quinoline insoluble content, specific gravity 1.185, and ash content 0.1%, and 50 parts by weight of secondary butanol were charged into an autoclave, and the air inside was replaced with _N2.
After purging with gas, it was sealed and a thermal reaction was carried out at 430°C for 30 minutes. The pressure at this time was 170Kg/cm ² G.

After the thermal reaction was completed, the light fraction containing unreacted secondary butanol was distilled off at 300°C and 35 Torr to obtain a pitch with a softening point of 116°C, TI of 4.8%, and traces of QI.

This pitch was heat treated at 470° C. and 10 Torr for 20 minutes in a N ₂ gas atmosphere to obtain a mesophase pitch. When the surface of this mesophasic pitch was polished and observed under a reflective polarizing microscope, it was as shown in FIG. It can be seen that the mesophase domain is larger than the comparative example shown in FIG. 10.

Comparative Example 3 The petroleum pitch used in Example 3 was heated at 470°C for 20 minutes in an _N2 gas atmosphere without undergoing a thermal reaction.
When heat treated at 10 Torr, caulking occurred. A mesophase pitch was obtained by heat treatment for 15 minutes under the same other conditions. When the surface of this mesophasic pitch was polished and observed with a reflective polarizing microscope, it was as shown in FIG.

Example 4 100 parts of coal tar pitch with a softening point of 82°C, TI of 11%, and QI of 0% and 50 parts of isopropanol were placed in an autoclave, and after replacing the air inside with N ₂ gas, the autoclave was sealed and subjected to a thermal reaction at 320°C for 90 minutes. I did it. The pressure at this time was 77Kg/cm ² G.

After the thermal reaction was completed, the mixture was cooled and the supernatant containing unreacted isopropanol was separated by decantation to obtain thermally reacted pitch. This pitch was placed in a flask and heat treated at 470°C for 6 minutes at 6 Torr to obtain mesophase pitch. The yield of this mesophace pitch based on the raw material coal tar pitch was 12%, the softening point was 330°C, and the mesophace content was 92%.

This mesophase pitch is heated to 365℃, extruded through a nozzle with a diameter of 0.5 mm, and wound onto a bobbin.
Pitch fibers with a thickness of μ were obtained.

After making this pitch fiber infusible, it is placed in an inert atmosphere.
Young's modulus of graphitized fiber fired at 2500℃ is 45T/
It showed a high value of mm ² .

Example 5 100 parts of coal tar pitch with a softening point of 82°C, TI of 11%, and QI of 0%, 2 parts of secondary butanol, and 0.02 parts of caustic potassium as a catalyst were placed in an autoclave, and the autoclave was sealed after replacing the air inside with N ₂ gas.
Thermal reaction was carried out at 450°C for 20 minutes. The pressure here was 6 kg/cm ² G. After the thermal reaction was completed, the reaction product was cooled and transferred to a flask without removing light components, and heated at 470°C for 3 minutes at 4 Torr.
A mesophase pitch was obtained by heat treatment. This mesophace pitch had a yield of 15% based on the raw material coal tar pitch, a softening point of 308°C, and a mesophace content of 78%. This mesophasic pitch was heated to 360°C, extruded through a nozzle with a diameter of 0.5 mm, and wound around a bobbin to obtain pitch fibers of 11 μm.

Comparative Example 4 When the coal tar pitch used in Examples 4 and 5 was treated under the same conditions as Examples 1 and 2, except that no alcohol was added, the pitch obtained under the conditions of Example 4 showed no softening. The temperature exceeded 400°C and the mesophase content was almost 100%.

Further, under the conditions of Example 2, coking occurred during the heat treatment after the thermal reaction. Therefore, the heat treatment temperature is 450
Mesophace pitch was produced by varying the processing time at ℃ and 4 Torr pressure, and the mesophase content was 92% and 78% as in Examples 1 and 2, but both were spun at softening points of 385℃ and 375℃, respectively. I couldn't do it.

Example 6 The same coal tar pitch used in Example 5 was thermally reacted without adding caustic potash and under the same conditions as in Example 5, and was further heat treated under the same conditions as in Example 5 without removing light oil. I obtained a mesophace pitch.

The softening point of this mesophase pitch was 332°C, which was 24% higher than that of the mesophase pitch of Example 5.
℃ showed a high softening point.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the amount of alcohol added in the thermal reaction and the softening point of mesophace pitch (70% mesophace content) after heat treatment. Figure 2 shows coal tar pitch and isopropanol.
This is an NMR spectrum of an oil containing alcohol distilled out after a thermal reaction at 350°C for 90 minutes. Figure 3A shows the IR spectrum of light components distilled after thermally reacting coal tar pitch and n-butanol, and Figure 3B shows the IR spectrum of n-butanol. Figure 4A is an IR spectrum of light components distilled after thermally reacting coal tar pitch and secondary butanol, and Figure 4B is an IR spectrum of secondary butanol. FIG. 5 is a polarized light micrograph of mesophasic pitch obtained by thermally reacting coal tar pitch with alcohol and then heat-treating the pitch. FIG. 6 is a polarized light micrograph of mesophase pitch obtained by heat-treating coal tar pitch. FIG. 7 is a polarized light micrograph of mesophasic pitch obtained by removing the QI content of soft coal tar pitch, then thermally reacting with alcohol, and then heat-treating the pitch. FIG. 8 is a polarized light micrograph of a mesophase pitch obtained by removing the QI content of the coal tar soft pitch and then heat-treating it. FIG. 9 is a polarized light micrograph of mesophase pitch obtained by thermally reacting petroleum pitch with alcohol and then heat-treating it. 1st
Figure 0 is a polarized light micrograph of mesophase pitch obtained by heat-treating petroleum-based pitch.

Claims (1)

[Claims] 1.250 by adding alcohol to heavy bituminous substances
A method for producing pitch for carbon products, which comprises carrying out a thermal reaction at a temperature of ℃ or higher, and then further heat-treating until mesophase is produced. 2. The manufacturing method according to claim 1, wherein the thermal reaction between heavy bituminous substances and alcohols is carried out under pressure. 3 Alcohols are added in an amount of 1% by weight or more based on heavy bituminous materials, and the thermal reaction is carried out at 300℃ or higher under pressure.
The manufacturing method according to claim 1, wherein the manufacturing method is carried out for more than 1 minute. 4. The manufacturing method according to claim 1, wherein the thermal reaction between heavy bituminous substances and alcohols is carried out under the catalytic action of a basic substance. 5. The manufacturing method according to claim 1, wherein the heat treatment is carried out after separating and removing unreacted alcohols. 6. Claim 1, wherein the pitch for carbon products is pitch for carbon fiber containing 40% or more of mesophace.
Manufacturing method described in section.