JPH0635578B2 - Method for producing pitch containing microsphere-shaped mesophase - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a pitcher containing a large amount of optically anisotropic small spherical mesophases produced by heat treatment of coal tar pitches or petroleum heavy oil pitches. The present invention relates to a production method and a high-yield production method of small spherical mesophases separated from such a pitch.

When the pits from which the insoluble solids have been removed are heat-treated at 350 to 500 ° C., optically anisotropic small spherical mesophases are formed in the pits during the process of polymerization of low molecular weight components. This small spherical mesophase is a kind of liquid crystal having a structure in which highly condensed polycyclic aromatic hydrocarbons are arranged in a certain direction, and is chemically, electrically, and magnetically active.
It is attracting attention as a new material not found in conventional carbon materials such as high chemical resistance.

Pitches containing these small spherical mesophases are used as binders for high-grade carbon materials such as high-density molded carbon materials and substitutes for aggregates, and by solvent separation from this pitch, etc.
The separated small spherical mesophases are used as a carbon material having a high added value such as a catalyst carrier, a chromatogram adsorbent, and carbon for electric resistance, and are expected to be used in a wider range in the future.

[Conventional technology]

Then, in order to generate small spherical mesophases,
The pits from which the insoluble solids have been removed are heat-treated. Generally, although the pits are slightly different depending on the type of the raw material pits, in the ordinary heat treatment, the obtained globular mesophases are about 20% by weight in the pits. When the heat treatment is further continued to increase the production amount, the small spheres are united with each other to form a flow pattern, and further the bulk mesophases are changed.

Therefore, conventionally, when a small spherical mesophase-containing pitch is obtained by heat treatment, the heat treatment must be stopped before the small spherical bodies are combined with each other, that is, when the generated small spherical mesophases is 20% or less. It was difficult to obtain pitches containing a high concentration of spherical mesophases, and the yield of mesocarbon microbeads obtained by solvent washing was small, and it was difficult to increase the yield.

In addition, the present applicant has previously proposed (Japanese Patent Application No. 56-192413) a method of converting a anisotropic structure into mesophases of small spheres by subjecting a pitch to a heat treatment and then performing a pressure reduction treatment in a molten state, but this method is small. Although the amount of spherical mesophases produced can be considerably improved, a higher level has been desired in recent years, and further some improvements are desired if possible because the operation requires some time.

[Problems to be solved by the invention]

As described above, conventionally, there has not been found a sufficiently satisfactory method for producing small mesophase microspheres from pits at a relatively high concentration and producing the mesophase, so-called mesocarbon microbeads, at a high yield. There is a situation.

[Means for solving problems]

Therefore, the inventors of the present invention have conducted further studies to solve such problems, and as a result, found that the amount of microspherical mesophases produced can be increased by irradiating ultrasonic waves at an appropriate point of the heat treatment. Reached

It is an object of the present invention to provide a method for producing small spherical mesophases in a high yield by an additional operation in an extremely short time. In the method of heat-treating the pits to generate the mesophase microspheres in the pits, it can be easily achieved by irradiating the pits with ultrasonic waves during or after the pit heat treatment.

The present invention will be described in detail below.

The pitches used in the present invention may be various known ones. Specifically, soft pitches from which light oil components of coal tar have been removed, or coal-based tar pitches such as pitch, which is a coal liquefaction, are preferred, but the present invention is not limited to this, petroleum, sheer oil, From various sources such as tar sands, there may be mentioned hydrocarbon substances containing condensed cyclic aromatic compounds having properties similar to pitch by appropriate treatment. These pits are subjected to a heat treatment after removing insoluble solids such as free carbon by an ordinary method, for example, sedimentation separation using an antisolvent, filtration, centrifugation and the like.

In the present invention, first, the pits are heat-treated to form an optically anisotropic structure. At that time, the ratio of the anisotropic structure to be formed is usually 10% or more, preferably about 3%.
Heat to 0-90%.

The ratio of the optically anisotropic structure in the present invention is a value calculated as the area ratio of the portion showing the optical anisotropy in the pitch sample under a polarization microscope at room temperature.

Specifically, for example, a Pitch sample crushed into a few mm square is embedded with a sample piece on almost the entire surface of a resin having a diameter of about 2 cm according to a conventional method, the surface is polished, and then the entire surface is covered with a polarizing microscope. It is obtained by observing under (100 magnification) and measuring the ratio of the area of the optically anisotropic portion to the total surface area of the sample.

The heat treatment conditions differ depending on the type of raw material pitch, but usually 3
50 to 500 ° C, preferably 380 to 450 ° C, 0.5
-100 hours, preferably 1 to 50 hours. If this heat treatment is performed in a stationary state, it is locally heated on the wall surface of the container, and that part is likely to become a flow-like mesophase, and since there is a small spherical mesophase, the heterogeneous mesophase-containing pitch is formed. Prone.

Even if the method of the present invention is applied to such a pitch, small spherical mesophase pitches having irregular particle sizes are likely to be generated, and therefore the pitch is agitated during the heat treatment, or an inert gas such as N ₂ is used. It is preferable to employ a homogenizing method such as blowing the mixture into the inner part or simultaneously performing both.

In the present invention, it is important to subject the mesophase-containing pitch obtained by such heat treatment to ultrasonic irradiation under the melting condition during or after the heat treatment.

By this ultrasonic irradiation, the mesophases that have developed into a flow pattern by heat treatment are also converted into almost spherical mesophases. The irradiation mode is, for example, a viscosity of the obtained mesophase-containing pitch of 100 poises or less, preferably 10 poises or less.
Ultrasonic irradiation may be performed by immersing the oscillation terminal from the pitch interface by about 0.5 to 50 m / m in a molten state such as poise or less as shown in FIG. At that time, the frequency used is 10
KHz or more, preferably 15 KHz or more, the amplitude is 10-100
μ, preferably 15 to 30 μ and time of 0.01 to 30
Minutes, preferably about 0.01 to 10 minutes.

In addition, FIG. 1 illustrates an example of an apparatus for irradiating ultrasonic waves in the present invention, in which a container 6 containing a heat treatment pitch 3 is immersed in a metal bath 4 heated by an external heater 5 and heat treated. The ultrasonic wave may be oscillated by immersing the tip of the ultrasonic oscillating terminal 2 connected to the ultrasonic oscillator 1 in the heat treatment pitch 3 while maintaining the pitch 3 in a molten state.

The particle size of the thus obtained small spherical mesophases can be relatively easily controlled to a particle size of 10 to 300 μ by appropriately adjusting the melting temperature, ultrasonic frequency, amplitude and irradiation time within the above range. it can.

If ultrasonic irradiation is performed together with the heat treatment of the pitch,
Of course, the irradiation may be performed over the entire period of the heat treatment, but since the significance of the irradiation is not fully exerted in the first half of the heat treatment and may be wasted, it may be irradiated in the second half of the heat treatment, particularly at the final stage. preferable. When the irradiation is performed after the heat treatment, it may be performed in a molten state after heating, or may be performed by once cooling and solidifying the mesophase-containing pitch and then melting again.

〔The invention's effect〕

As described above in detail, in the present invention, a high-concentration small spherical mesophase of 30 to 40% or more is obtained by a simple means of heat-treating pits to sufficiently generate mesophases and then irradiating with ultrasonic waves. It is useful as a method for producing pitches containing a large amount of small spherical mesophases, since the pitches containing them can be easily obtained in good yields, and the yield of mesocarbon microbeads after solvent washing finally obtained is significantly high. Will be improved.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Example 1 Pitch (Ti 6.8%, Qi 0%) from which a light fraction of coal tar was removed and insoluble solids were removed by sedimentation separation using an ordinary antisolvent, was blown with N ₂ gas under stirring to 440. Heat treatment was performed at 1 ° C. for 1 hour. The formed optically anisotropic mesophases were about 50%, and most of them obtained a flow pattern-like pitch. This pitch 15g 44
As a result of irradiating ultrasonic waves with a frequency of 19KHz with a width of 15μ for 10 minutes in the molten state at 0 ° C, almost all the flow pattern mesophases were changed to 10-300μ small spherical mesophases. The concentration of the microsphere mesophases therein was 50%.

30 g of quinoline was added to 10 g of the pits containing the mesophase microspheres obtained in this way, and the mixture was stirred at 90 ° C. for 1 hour and then passed through a 5 μ-filter, and then 10 parts of quinoline was added again and the above operation was repeated. Then, it was washed with acetone and dried to obtain 3.5 g of mesocarbon micro beads having a particle size of 10 to 300 μm.

Comparative Example 1 The same pitch as in Example 1 which was heat-treated at 440 ° C. for 1.0 hour was used, and after heating for 10 minutes at 440 ° C. without ultrasonic irradiation, the same treatment as in Example 1 was partially performed. Almost all of the small spherical mesophases were formed into flow pattern mesophases.

Example 2 A pitch similar to that in Example 1 was used in the same manner at 440 ° C. and 2.
Heat treatment was performed for 5 hours. The formed optically anisotropic mesophase was about 70%, which was almost a flow pattern. When this pitch was irradiated with ultrasonic waves in the same manner as in Example 1, all the flow patterns were changed to small spherical mesophases of 10 to 300 µ, and the concentration in the pitch was 70%.

30 g of quinoline was added to 10 g of the globules containing the mesophase microspheres thus obtained, stirred at 90 ° C. for 1 hour, and then passed through a 5 μ filter, and 10 times of quinoline was added again. After repeated washing with acetone and drying, 5.0 g of mesocarbon microbeads having a particle size of 10 to 300 μm was obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating an example of an ultrasonic wave irradiation device used in the present invention. 1: Ultrasonic oscillator 2: 〃 〃 terminal 3: Heat treatment pitch 4: Metal bath 5: Heater 6: Container

Claims (1)

[Claims] 1. A method of heat-treating pits from which insoluble solids have been removed to generate small spherical mesophases in the pits, wherein the pits are exposed to ultrasonic waves during or after the heat treatment. A method for producing a microsphere-containing mesophase-containing pitch, comprising: