JPS59129288A - Classification of pitch - Google Patents

Abstract

PURPOSE:To efficiently separate a mixt. of pitches having particle size <= about 1mm. and a benzene solvent into a toluene insolubles-free clear soln. and a precipitate primarily composed of toluene insolubles by means of centrifugal separation. CONSTITUTION:A toluene insolubles-contg. pitch such as coal tar pitch or petroleum pitch is crushed into partcle size <= about 1mm. in a hammer crusher, etc. 1pt.wt. obtd. crushed pitch is mixed with not less than 5vol% benzene solvent and the resulting mixt. is separated into a toluene insolubles-free clear soln. substantially contg. no benzene insolubles and a precipitate primarily composed of toluene insolubles by centrifugal separation at a separation efficiency >=1X 10<4>G.sec.

Description

[Detailed description of the invention] uses pitches as raw materials to produce carbon fibers, binders for electrodes,
This invention relates to a separation method for extracting specific components from pitches in the production of impregnating agents or special carbon materials.

The carbon utilization will be explained below by taking as an example the production of high elastic carbon fiber.

As a method for producing high-modulus carbon fibers from pitches, a method using a mesophase in a liquid crystal state is known.

In this method, a pitch containing menphase (
Since there is a process of melt spinning the mesophase pitch (hereinafter referred to as mesophase pitch), the mesophase pitch is required to exhibit a low melt viscosity.

When producing this low-viscosity mesophase pinch, the present inventors have found that the following method is suitable. That is, coal tar or coal tar pinch is extracted with benzenes, and only components soluble in benzenes solvents (hereinafter referred to as B.S.) are extracted. That B. S. 35
Heating at a temperature of 0 to 500°C, at a temperature of 20 wt% or more of the toluene insoluble content (hereinafter referred to as T.1.) in the pitch, so that nitrobenzene insoluble content (hereinafter referred to as N.1.) is not substantially generated. Polymerize. The heated pitch was extracted with a benzene solvent to remove the soluble content, and the T. 1. is 70 wl;
The pitch is 4 or more, and the pitch is heat-treated at 350 to 500°C to obtain a mesophase pitch having a mesophase content of 50 vol% or more.

Then, this mesophase pitch is melt-spun, infusible,
This is a method of producing high modulus carbon fiber by carbonization.

Here, T, I. is measured by JIS-24'25 tar pitch toluene insoluble content determination method, N, I
.

is measured using nitrobenzene instead of quinoline as a solvent in J'IS-K2425 quinoline solution determination method (centrifugation method) for tar pitches.

According to the above production method, N is used as a raw material for menphasic pitch that can be spun with low viscosity. ■ Substantially does not contain T
, 1. A pitch containing 70 wt% or more of is suitable.

In order to obtain pitch with such properties, two separation steps are required; the first is a step to separate only B and S from the coal tar pitch, and the second is a step to separate only B and S from the coal tar pitch. B and S obtained in the separation process.

Heating pinch (N, 1.=Owt%, T,
1. ≧20wt%) to T, 1. This is a step of separating components containing 70 wt% or more of.

On the other hand, JIS, which is considered to be harmful as a raw material for manufacturing carbon materials,
-Quinoline solubles specified in K2425 (hereinafter referred to as Q)
1. The following four methods are typically known as methods for removing .

(1) Heat treatment of coal-based heavy oil Q.1. A method of increasing the particle size and separating and removing it.

(2) Mixing organic solvent with coal-based heavy oil Q, 1. A method for separating and removing insoluble precipitates containing.

(3) Mix an aliphatic solvent with coal-based heavy oil, heat and stir, and then let stand to cool. Q.1. A method for separating and removing insoluble precipitates containing.

(4) A method in which an aliphatic solvent and an aromatic solvent are mixed with coal-based heavy oil, and insoluble precipitates containing Q and L are separated and removed.

However, in all of these methods, basically Q,
1. With the particle as the nucleus, Q, 1. By attaching β-reno7 (a component soluble in quinoline and insoluble in benzene) to the particle surface, the particles are made coarser and insoluble substances can be easily separated.Q,I.

Although it is an excellent removal method, when planning to apply it in the process of the above-mentioned production method, components insoluble in benzene solvents (hereinafter referred to as B, 1.) will be mixed into the clarified liquid, so It is too early to apply to separation processes. Also, the second
In the raw materials introduced into the separation process, there are no q, r, or precipitate nuclei, so insoluble substances do not become coarse particles, making separation difficult. Conventional methods are also not applicable to the second separation step.

The present invention provides a completely new separation method in place of the conventional method.

That is, the gist of the present invention is to grind pitch containing toluene-insoluble matter to substantially 1 rMn or less, and to grind the ground pitch and benzene in an amount of 5 parts by volume or more per 1 part by weight of the ground pitch. After mixing with the solvent, centrifugation is performed at a centrifugal efficiency of 10' Gsec or more, and the mixture is separated into a clear liquid that substantially contains toluene-insoluble matter and a precipitate that is mainly composed of toluene-insoluble matter. There is a method for sorting pinched items, which is characterized by the following.

The present inventors discovered an extremely important fact while conducting a solvent extraction separation test for coal tar pitch.

That is, it has been found that when pitches are extracted and separated using a solvent, a precipitate of any quality can be easily obtained using an industrial-scale centrifugal separator by appropriately selecting the particle size of the pitch and the solvent ratio. Here, the centrifugal efficiency (product of centrifugal force and time) of an industrial-scale centrifuge is up to 6X1
It is about 0"Gsee.

According to experiments conducted by the present inventors, the results shown in the drawings were obtained. The figure shows T, 1. Coal tar pitch containing 25 wt% of
Results of measuring the amount (wt%) of T in the precipitate that was extracted with benzene at 80°C and centrifuged at a centrifugal efficiency of 2X 10" G see with varying pitch weight (g). This shows that

According to the figure, by appropriately selecting the particle size of pitch and the solvent ratio, T in the precipitate can be reduced to 1. It can be seen that it is possible to adjust the amount to any desired amount. In addition, as mentioned above, 70
T of wt% or more, 1. It can be seen that in order to obtain a pinch containing .

The next important fact is that the clarified liquid obtained by separation as described above does not substantially contain B soil. Therefore, for the separation of only the first B and s, any particle size and solvent ratio shown in the drawings may be selected, but the particle size of the pitch may be 1 mm larger, or the solvent ratio may be selected. If it is smaller than 5, the yield of B and S will be as low as 30% or less, making it unsuitable for the above-mentioned production method.

Here, the pitches targeted by the present invention include coal tar pitch, petroleum pitch, and hydrogenated pitch obtained by adding hydrogen to these pitches. Further, a hammer crusher or the like is used as a means for crushing the pitch to a particle size of substantially I mm or less.

In addition, the particle size of the pinch before crushing is in the form of flakes with a culm length of 3 to 5 mm x 50 to 6 mm.Furthermore, even if you do not crush all of them to less than 1 loaf, particles of less than i rrm can be crushed. 80% or more is sufficient.The extracting solvent is not limited to hexane, but may also be monocyclic aromatic nonpolar solvents such as beersene, toluene, xylene, etc., and mixtures thereof, such as crude benzene.

In addition, in the present invention, the centrifugation efficiency is
The reason for setting it above G-see is that if it is lower than that, B, 1. This is because it will be mixed in.

As described above, according to the present invention, by centrifugation, it is possible to industrially easily separate a clear liquid that does not substantially contain toluene-insoluble matter and a precipitate whose main component is toluene-insoluble matter.

The method of the present invention will be further explained in Examples below.

[Example 1] T, 1. Coal tar pitch containing 23% of
After extraction with a solvent for 30 minutes, the mixture was cooled to room temperature and centrifuged using a centrifuge, and the solvent was removed by distillation from the resulting clear liquid to obtain pitch. The pitch yield and T, 1. are shown in Table 1.

As is clear from Table 1, by the method of the present invention, substantially T, 1. It can be seen that pitch free of 100% is readily obtained in high yields in industrial-scale centrifuges.

Table 1 [Example 2] The pitch obtained in Example (2) of Table 1 was heated to 3
Heated pitch was obtained by heating polycondensation for 0 minutes. The properties of this heating pitch are N and I. -0%, T, 1. =30%. This heated pitch was extracted with a solvent at 80°C for 30 minutes, then cooled to room temperature and centrifuged using a centrifuge to obtain a precipitate. The results of measuring T and S of the precipitate were used as a second
Shown in the table. As is clear from Table 2, T and S can be extracted and separated by the method of the present invention.

It can be seen that separation of precipitates containing up to 30% of .

Table 2 [Example 3] The precipitate obtained in Table 2 Example (8) was heat-treated at 430°C to produce Mesofx-Zubich with a menphase content of 85 cm, and melt-spun at 360°C. A pitch yarn with a diameter of 15 μm was obtained. This pitch yarn is heated at a rate of 05℃ in the air.
After raising the temperature to 280° C./min, the temperature was maintained for 30 minutes to make it infusible. Next, this infusible yarn was heated to 1000''C in Ar at a temperature increase rate of 1°C/min, and then held for 5 minutes to carbonize.Then, this carbonized yarn was heated in Ar at a temperature increase rate of 20°C/min for 20 minutes.
After raising the temperature to 00°C, it was held for 5 minutes to graphitize it. Table 3 shows the physical properties of the obtained carbon fiber.

Table 3 It can be seen from Table 3 that high modulus carbon fibers having high strength and modulus of elasticity can be produced by the method of the present invention.

[Brief explanation of drawings]

Pitch particle size, solvent ratio and T, I in the precipitate of Hacoal tar pitch. FIG. Pitch + η tooth travel diameter (/Jm) Procedural amendment (method) 1. Indication of the case 1988 Patent Application No. 3 ], No. 20 2. Title of the invention Method of separating pitches 3. Case of the person making the amendment Relationship between Patent Applicant 4 and Attorney 〒136 8 Contents of Amendment Tables 1 to 3 on pages 9 to 11 are attached as attached. Table 1

Claims (1)

[Claims] (1) Substantially pitches containing toluene-insoluble matter]
After grinding the ground pitch to 1 mm or less and mixing this ground pitch with 5 parts by volume or more of a benzene solvent per 1 part by weight of this ground pitch, centrifugation is performed at a centrifugal efficiency of 1Xl04G-see or higher to obtain a toluene-insoluble powder. A method for separating pitches, which is specially designed to separate pitches into a clear liquid containing substantially no toluene-insoluble matter and a precipitate whose main component is toluene-insoluble matter.