JP4933151B2 - Binder pitch manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a coal tar-based binder pitch used as a binder for carbon materials such as graphite electrodes or carbon / carbon composite materials.

  Carbon materials such as graphite electrodes or carbon / carbon composite materials (hereinafter also referred to as carbon material composite materials) are required to have characteristics such as high mechanical strength, high electrical conductivity and high thermal conductivity. In order to obtain the properties, a binder for adhering and fixing the aggregates is indispensable. Usually, in order to satisfy the properties, a binder pitch obtained by heat treatment of coal tar pitch is used. Yes. That is, the carbon composite material is manufactured by kneading and forming an aggregate such as coke and a binder pitch, firing, and then performing graphitization.

  There are various performances required for the binder pitch, and examples thereof include a fixed carbon amount and a quinoline insoluble content. The amount of fixed carbon is usually about 55 to 60% by mass. As the amount of fixed carbon in the binder pitch increases, the carbonization yield during firing of the carbon material composite increases, and as a result, the bulk density of the carbon material composite increases and the mechanical strength also increases. The amount of quinoline insoluble matter (also referred to as QI) is usually about 7 to 14% by mass. It consists of a polymer of an aromatic compound produced by thermal polymerization when distilled. Since the free carbon and the high molecular weight component (heavy component) of the polymer hinder the crystal growth of graphite in the carbonization process, it is preferable that these are as small as possible. On the other hand, since the low molecular weight component (light component) of the polymer is likely to be fixed carbonized, it is preferable that the amount is large.

  Conventionally, the binder pitch is produced by distilling coal tar and further heat-treating the coal tar pitch which is the distillation residue [Patent Documents 1 and 2]. However, in this method, a polymer is formed by concentration by distillation and thermal polymerization of aromatic compounds, and the quinoline insoluble content increases, so the amount of light components in the quinoline insoluble content suitable for the binder pitch is controlled. Difficult to do.

  In Patent Document 3, after heat treatment of coal tar pitch at 450 ° C., extraction and filtration are performed using oil in tar having a boiling range of 150 to 200 ° C., and the quinoline insoluble content is less than 0.1% by mass. A method for producing impregnated pitch is described. In this method, in order to obtain an impregnation pitch having a quinoline insoluble content of less than 0.1% by mass, the extraction / filtration temperature is lowered (for example, less than 100 ° C.), and the quinoline insoluble content is shifted to the non-tar medium oil side. I am trying to do that. The obtained impregnated pitch having a quinoline insoluble content of less than 0.1% by mass is unsuitable for the binder pitch.

Japanese Patent Laid-Open No. 3-197590 JP 2000-204375 A JP 2004-285130 A

  In the present invention, the amount of quinoline insolubles in the binder pitch, which greatly influences the performance of the binder used in the production of carbon materials such as graphite electrodes and / or carbon / carbon composite materials from coal tar pitch, is easily within a suitable range. It is an object of the present invention to provide a method for producing a binder pitch that can be controlled in a controlled manner and has a carbon yield that is not different from the conventional one.

The present invention is as follows (1) to (2).
(1) A heat treatment step of heat treating the coal tar pitch to obtain a binder pitch component containing a polymer of an aromatic compound in the coal tar pitch, and the heat treated coal tar pitch having a boiling point range of 200 to 360 ° C. A solvent extraction and filtration step of adding a middle oil of tar, solvent extraction and filtration of the binder pitch component in a temperature range of 100 to 200 ° C. to obtain a filtrate containing the binder pitch component, and the tar contained in the filtrate A method for producing a binder pitch, comprising: an extraction solvent removing step of removing middle oil to obtain the binder pitch component.

(2) The method for producing a binder pitch according to (1), wherein the quinoline insoluble content in the binder pitch is 1% by mass or more and less than 7% by mass.

  According to the present invention, compared with the conventional method, the amount of quinoline insoluble in the coal tar binder pitch used in the production of carbon materials such as graphite electrodes and / or carbon / carbon composite materials is small, and the amount of fixed carbon is the same as before. Things can be manufactured.

Compared with the conventional method for producing a coal tar binder pitch, the present inventor uses a high boiling point tar oil as an extraction solvent, and increases the extraction temperature to obtain a high thermal reaction history. If a heavy binder component of free carbon and quinoline insoluble matter that inhibits carbonization reaction is separated to the solid side by performing filtration at a high temperature, it is converted to fixed carbon in the filtrate. The present inventors have found that a light component of easily quinoline-insoluble matter can be distributed in a large amount, and have arrived at the present invention.
In addition, the suitable amount of quinoline insolubles of the binder pitch obtained by the manufacturing method of this invention is 1 mass% or more and less than 7 mass%, and the amount of fixed carbon is 55-60 mass% as the past.

The manufacturing method of the binder pitch of this invention is demonstrated based on the process flow shown in FIG.
(1) The raw material is coal tar pitch. In the present invention, it is preferable to use a pitch having a quinoline insoluble content of 0.5 to 6.0 mass%, preferably 0.5 to 2 mass%. When the quinoline insoluble content is less than 0.5% by mass, the heat treatment time of the coal tar pitch becomes long, and the productivity becomes low. On the other hand, if it exceeds 6.0% by mass, the amount of quinoline insoluble in the resulting binder pitch will be excessive.

(2) The raw material coal tar pitch of (1) is heat-treated. The heat treatment is preferably performed in the range of 400 to 500 ° C, more preferably in the range of 420 to 460 ° C. Thereby, the polymerization degree of the aromatic compound in coal tar pitch increases, and a binder pitch component can be obtained. The heat treatment time is 3 hours or more, preferably 4 to 5 hours, so that the polymerization of the aromatic compound proceeds sufficiently.
Polymerization of the aromatic compound gives a light component containing a relatively low molecular weight polymer and a heavy component containing a relatively high molecular weight polymer, but the binder pitch should have a high ratio of light components. Therefore, it is preferable to avoid rapid heating and carefully control the temperature so as not to overheat.

(3) Solvent extraction of binder pitch components including polymers of aromatic compounds from coal tar pitch after heat treatment of (2) above using coal tar tar oil with a boiling range of 200-360 ° C. To do. When the boiling point range of the oil in tar is less than 200 ° C., the light component of the quinoline insoluble component useful for the binder pitch is not extracted by the oil in tar, which is not suitable. On the other hand, if the temperature exceeds 360 ° C., the oil in tar is unsuitable because the extraction power is too large and there is a possibility that even heavy components in the quinoline insoluble matter may be extracted. A preferred boiling range is 200 to 300 ° C, more preferably 200 to 260 ° C.
Although the usage-amount of a tar middle oil is not specifically limited, It is 0.5 to 5.0 times with respect to the coal tar pitch 1 after heat processing by a volume ratio. Considering the pitch yield and the like at the time of distillation in the next step, it is preferably 1.0 to 3.0 times. When the capacity ratio is less than 0.5 times, components that cannot be extracted remain, causing a decrease in pitch yield. Conversely, if it exceeds 5.0 times, an increase in the amount of extraction cannot be expected, so that it is not economical.

  The solvent extraction is performed in a temperature range of 100 to 200 ° C. When the extraction temperature is less than 100 ° C., the distribution coefficient of the quinoline insoluble component in the binder pitch component during solvent extraction becomes small, and sufficient solvent extraction cannot be performed. On the contrary, if it exceeds 200 degreeC, an extraction solvent will volatilize. A preferable solvent extraction temperature is 100 to 150 ° C.

(4) The oil in tar containing the binder pitch component obtained by the solvent extraction of (3) is separated from the coal tar pitch by filtration. In order to maintain the partition coefficient of the quinoline insoluble matter in the high temperature extraction, the filtration temperature is 100 to 200 ° C, more preferably 100 to 150 ° C.
The filtration can be performed using a general filtration device such as Nutsche type.

  (5) The next extraction solvent removal is, for example, distillation. The tar middle oil containing the binder pitch component obtained by the filtration in (4) is distilled to separate the binder pitch component from the tar middle oil in the filtrate to obtain a binder pitch. During distillation, the softening point of the binder pitch can be adjusted by adjusting the distillation temperature to obtain a binder pitch having a desired quality. Distillation may be carried out at normal pressure or reduced pressure, and if necessary, heat treatment may be performed after distillation for the purpose of adjusting the softening point.

  (6) The binder pitch obtained by the distillation of the above (5) is used as a binder of a carbon material composite after being adjusted in particle size or dried as necessary. Thus, the quinoline insoluble content is 1% by mass or more and less than 7% by mass, preferably 5 to 6.5% by mass, the fixed carbon content is 55 to 60% by mass, preferably 57 to 60% by mass, A binder pitch having an insoluble content of 28 to 38% by mass and a softening point of 80 to 120 ° C. can be obtained.

Examples of the present invention and comparative examples will be described below. Of course, the invention is not limited to these examples,
Example 1
Coal tar pitch (softening point 82 ° C., quinoline insoluble content 2.0 mass%, toluene insoluble content 18 mass%, fixed carbon content 52 mass%) was heat treated at a temperature of 455 ° C. for 4 hours. To the obtained coal tar pitch after the heat treatment, 1.5 times by volume of coal tar tar middle oil (boiling range: 200 to 250 ° C.) was added, and extraction was performed at a temperature of 140 ° C. Thereafter, the resultant was subjected to hot filtration at a temperature of 140 ° C. and separated into a filtrate containing coal tar pitch and a binder pitch component (a quinoline insoluble content of 3.4% by mass and a toluene insoluble content of 22% by mass). The obtained filtrate was distilled to remove tar oil, and a binder pitch (softening point 91.2 ° C., fixed carbon amount 57 mass%) was obtained.

The physical properties of coal tar pitch and binder pitch were measured in accordance with JIS K2425 regulations as follows.
(Softening point)
It was measured by the ring and ball method. That is, coal tar pitch or binder pitch under 840 μm (20 mesh) sieve is heated and melted at a temperature not exceeding 50 ° C. from the estimated softening point, poured into a ring of diameter × height = 16 × 6.4 mm, and solidified I let you. Next, this ring was placed on a sample shelf, and a steel ball having a diameter of 9.525 mm and a mass of 3.5 g was placed at the center of the ring. Immerse this shelf in glycerin, raise the bath temperature at 5 ° C / min, soften the coal tar pitch (binder pitch) and soften the temperature when the steel ball reaches the bottom plate 25.4mm below the ring Points.

(Quinoline insoluble content [QI])
1 g of coal tar pitch or binder pitch under 250 μm (60 mesh) sieve was dissolved in 20 ml of quinoline at about 75 ° C. Next, the soluble matter was removed by suction filtration, the residue was washed with quinoline and acetone, and the residue after drying was weighed to calculate the amount of quinoline insoluble matter.

(Toluene insoluble content [TI])
Coal tar pitch or 2 g of binder pitch under a 250 μm (60 mesh) sieve was mixed with 100 ml of warm toluene, and heated and dissolved by refluxing. Next, the soluble component was removed by suction filtration while it was hot, the residue was washed with toluene and acetone, and the residue after drying was weighed to calculate the toluene-insoluble component.

(Fixed carbon content)
Coal tar pitch or 1 g of binder pitch under a 250 μm (60 mesh) sieve was placed in a crucible with a porcelain drop lid and heated for 30 min in an electric furnace maintained at 430 ° C. without the lid, to remove volatile matter. Next, cover and place in a porcelain B-type crucible, cover the periphery with coke grains and cover the cover, then heat in an electric furnace maintained at 800 ° C. for 30 minutes, cool, and then carbide (residue) The amount of fixed carbon was calculated by weighing.

(Comparative Example 1)
Coal tar (quinoline insoluble content 5.0% by mass, toluene insoluble content 11% by mass, fixed carbon content 20% by mass) was distilled and coal tar pitch (softening point 60 ° C., quinoline insoluble content 8% by mass, toluene insoluble content amount 26% by mass and 40% by mass of fixed carbon). The coal tar pitch was heat-treated at a temperature of 360 ° C. for 2 hours, and binder pitch (softening point 92.5 ° C., quinoline insoluble content 10.2% by mass, toluene insoluble content 32% by mass, fixed carbon content 56.1% by mass) Got.

(Comparative Example 2)
In Example 1, the extraction temperature performed by adding coal tar-based tar oil (boiling range: 150 to 200 ° C.) is changed from 140 ° C. to 110 ° C., and the subsequent filtration temperature is changed from 140 ° C. to 110 ° C. Produced a binder pitch under the same method and conditions as in Example 1. The physical properties of the obtained binder pitch were measured in the same manner as in Example 1, and the results are shown in Table 1.

From the comparison between Example 1 and Comparative Example 1, it is clear that the binder pitch obtained by the production method of the present invention has a small amount of quinoline insolubles and the amount of fixed carbon is similar to the conventional one.
Further, from comparison between Example 1 and Comparative Example 2, it can be seen that when an extraction solvent having a low boiling point is used, the amount of quinoline insoluble component is small, the amount of fixed carbon is small, and it is not suitable as a binder pitch.

It is a process flow figure of the manufacturing method of the present invention.

Claims (2)

  A heat treatment step of heat-treating the coal tar pitch to obtain a binder pitch component containing a polymer of an aromatic compound in the coal tar pitch; Addition and filtration of the binder pitch component in a temperature range of 100 to 200 ° C. to obtain a filtrate containing the binder pitch component, and removal of the tar oil contained in the filtrate And an extraction solvent removing step for obtaining the binder pitch component.   The method for producing a binder pitch according to claim 1, wherein the quinoline insoluble content in the binder pitch is 1 mass% or more and less than 7 mass%.

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