JP2546801B2 - Method for manufacturing pitch for carbon material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an efficient method for producing a carbon material, particularly a pitch for a carbon material suitable for producing a carbon fiber.

[Problems to be Solved by Conventional Techniques and Inventions] Various methods have been proposed as to the method for producing a raw material pitch for carbon fibers, but those which are sufficiently satisfactory in terms of spinnability and strength, particularly spinnability are obtained. Has not been done.

As a result of studies on the improvement of the spinnability of the raw material pitch for carbon fiber, the present inventors have found that the paraffin content in the petroleum heavy oil, which is the raw material, becomes bubbles during spinning and is a major cause of lowering the spinnability. Found.

Further, as a result of further study on the conventional method for producing a raw material pitch for carbon fiber, it was found that the raw material pitch by any of the production methods is insufficient for removing the paraffin component. Paraffin components generally have a low molecular weight, and as described above, not only do they become bubbles during spinning to reduce the spinnability of the pitch, but they also cause a reduction in the strength of the carbon fibers obtained therefrom.

However, if this paraffin component is completely removed by simple distillation, a large amount of components other than the paraffin component are also removed at the same time, resulting in a decrease in yield, which is not preferable.

The present invention solves the above-mentioned conventional problems, removes only the paraffin component without lowering the yield, generates few bubbles during spinning, has excellent spinnability, and is a carbon material with excellent strength. It is an object of the present invention to provide a method for efficiently manufacturing a commercial pitch.

[Means for Solving Problems] That is, in the present invention, the raw material petroleum-based heavy oil or a heat-treated product thereof is preliminarily heated at a temperature of 400 to 500 ° C. under pressure when producing a carbon material pitch from the petroleum-based heavy oil. It is 5 to 50 kg / cm ² , and the value of the pressurization degree F calculated from the following formula is 3.1 to 4.6.
The present invention provides a method for producing a pitch for carbon material, which comprises performing deparaffinization treatment under the following conditions and then heat treating the obtained treated oil at a temperature of 350 to 550 ° C under reduced pressure.

[In the formula, P indicates pressure (kg / cm ² ), and T indicates temperature (° C). Examples of the petroleum-based heavy oil include catalytic cracking residual oil of petroleum, thermal cracking residual oil, hydrocracking residual oil, and the like.
In particular, composition and properties are not specified. The heat treatment conditions for the heat treated product are not particularly specified.

In the present invention, the above-mentioned heavy petroleum oil or a heat-treated product thereof is used as a raw material, and this is deparaffinized in advance under specific conditions.

First, the temperature during the deparaffinization treatment is 400 to 500 ° C, preferably 430 to 480 ° C.

Here, if the temperature is lower than 400 ° C, deparaffinization cannot be completely performed, while if it exceeds 500 ° C, coke is partially formed, which is not preferable.

The pressure is usually 5 to 50 kg / cm ² .
Here, if the pressure is less than 5 kg / cm ² , the yield is lowered, while if it exceeds 50 kg / cm ² , deparaffinization becomes difficult to be completely performed.

Regarding the above-mentioned temperature and pressure, it is difficult to find the optimum condition because there is a trade-off between them, but as a result of various studies by the inventors, the F parameter (function of temperature and pressure represented by the following empirical formula ( It has been found that optimum conditions can be obtained based on the degree of pressurization F).

[F is the pressure parameter, P is the reaction pressure (kg / cm ² ), and T is the reaction temperature (° C). ] And this F parameter is 3.1 to 4.6, preferably 3.
The temperature and pressure are selected so as to be 5 to 4.5, particularly preferably 4.0 to 4.5.

That is, the pressure parameter It is optimal if it satisfies the formula. If the pressurization degree parameter represented by the above formula is less than 3.1 or exceeds 4.6, it becomes difficult to remove the paraffin component, and the yield of pitch is lowered due to partial coking, which is not preferable. The heat treatment time is difficult to unambiguously determine because it depends on the temperature and pressure, but it is usually 0.1 to 24 hours, preferably 0.5 to 5 hours.
Time.

In this way, the deparaffinization treatment is performed to substantially remove the paraffin component. Here, "substantially removing paraffin components" means not only completely removing 100% paraffin components, but also a very small amount of paraffin components that does not adversely affect spinnability, for example, 0.5 wt% of paraffin components. It is intended to include the case where the minutes remain.

Then, the resulting treated oil under reduced pressure, the temperature 350 ~ 550 ℃,
Heat treatment is preferably performed at 400 to 500 ° C.

If the heat treatment temperature is lower than 350 ° C., the reaction is insufficient, which is not preferable. On the other hand, if the temperature is higher than 550 ° C., carbonization proceeds excessively, which causes coking, which is not preferable. Also, this heat treatment is carried out under reduced pressure, usually at 0.
It is carried out under the condition of 1 to 50 Torr, preferably 0.5 to 5 Torr. If the pressure is less than 0.1 Torr, the yield is lowered, which is not preferable. On the other hand, if the pressure exceeds 50 Torr, the conversion to the meso phase is insufficient, which is not preferable. Further, the time for this heat treatment is usually 10 minutes to 2 hours. Although this heat treatment can be performed using various reactors, it is preferably performed using a thin film evaporator.

As described above, it is possible to obtain a carbon material pitch that is particularly suitable for carbon fibers and the like.

The carbon material pitch thus obtained is used for the production of various carbon products. For example, in order to produce a pitch-based carbon fiber, the pitch is first melt-spun and then infusibilized by a conventional method. It may be fired.

[Examples] Next, the present invention will be described with reference to Examples.

Examples 1 and 2 and Comparative Examples 1 to 4 A heavy petroleum oil was subjected to pressure heat treatment under the conditions shown in Table 1, deparaffinized, and then decompressed using a thin film evaporator (450 ° C, 1 Torr, 1 hour) to obtain a raw material mesophase pitch for carbon fiber. This has a hole diameter of 0.3 mm and a length of 1.2 m
It was passed through a capillary of m, extruded at a shear rate of 400 sec ^-1 , and wound at a speed of 500 m / min. 300 fibers obtained
After infusibilizing treatment at 30 ° C. for 30 minutes, firing was performed at 1500 ° C. Table 1 shows the residual paraffin content after pressure heat treatment, the thread cutting time during spinning, the strength and elastic modulus of carbon fiber after firing. The qualitative and quantitative determination of the paraffin content was based on TLC-FID, and the softening point was measured using an elevated flow tester.

[Effects of the Invention] According to the method of the present invention, only the paraffin component is removed without lowering the yield, the foaming of the bubbles is small during spinning, the spinnability is excellent, and problems such as thread cutting occur. Rarely. Moreover, the obtained carbon material has excellent tensile strength and elastic modulus.

Therefore, the present invention can be effectively used for the production of carbon materials, especially carbon fibers.

Claims (4)

(57) [Claims] 1. When producing a pitch for carbon material from petroleum-based heavy oil, the raw material petroleum-based heavy oil or a heat-treated product thereof is preliminarily heated to a temperature of 400 to 500 ° C. and a pressure of 5 to 50 kg / cm ² . In addition, the deparaffinization treatment is performed under the condition that the value of the pressurization degree F calculated from the following formula is 3.1 to 4.6, and the obtained treated oil is then heat-treated at a temperature of 350 to 550 ° C under reduced pressure. A method for manufacturing a pitch for a carbon material. [In the formula, P indicates pressure (kg / cm ² ), and T indicates temperature (° C). ] 2. The method according to claim 1, wherein the pressure F is 4.0 to 4.5. 3. The manufacturing method according to claim 1, wherein the subsequent heat treatment is performed using a thin film evaporator. 4. The manufacturing method according to claim 1, wherein the carbon material is carbon fiber.