JPS6036594A - Preparation of pitch for carbon material - Google Patents

Abstract

PURPOSE:To obtain pitch useful for preparing especially carbon fiber, having a low softening point and improved spinnable properties, by using a heavy oil obtained by fluid catalytic cracking of petroleum, etc. and a residual oil fraction of hydrogenation product of petroleum heavy oil as raw materials. CONSTITUTION:A mixture of (A) a heavy oil having >=200 deg.C boiling point obtained by fluid catalytic cracking or thermal cracking and (B) a residual oil fraction of a formed oil obtained by hydrogenating a petroleum heavy oil is heat-treated at 350-450 deg.C (preferably at 380-420 deg.C), to give pitch usually containing 30-80wt% mesophase, from which pitch substantially containing 100wt% mesophase is separated. A heavy oil having 200-450 deg.C boiling point among a reaction product obtained by fluid catalytic cracking of gas oil, normal-pressure residual oil, etc. in the presence of a silica alumina catalyst, etc. at 450-550 deg.C may be cited as the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing pitch for a carbon material, and more specifically, a carbon material with a low softening point and good spinnability. It has long been known as a pitch manufacturing method suitable for manufacturing carbon fiber, and its performance has been highly evaluated. Carbon PA fibers have been produced using polyacrylonitrile as a raw material, but the resulting carbon fibers have the drawbacks of being expensive and having a low carbonization yield. Therefore, in recent years, various methods for producing carbon fiber using pitch as a raw material have been proposed.

However, pitch-based carbon fibers have problems such as difficulty in spinnability and poor performance such as strength and elastic modulus. For example, in a mixture of mesophase pitch and isotropic pitch with a mesophase pitch content of 40 to 90%, the compatibility between mesophase pitch and isotropic pitch is poor, and uniform spinning is difficult. .

On the other hand, if the entire pitch is essentially 100% mesophase,
Problems arise in that the softening point and viscosity increase, making it difficult to spin, and the resulting coke formation makes it unusable as a fiber raw material. In addition, methods have been proposed in which mesophase-containing pitch obtained by various methods is treated with a solvent to elute isotropic pitch, and the mesophase pitch is separated and used as a carbon fiber material. However, the pitch obtained by this method has problems such as recovery of the solvent. Furthermore, a method is known in which the mesophase pitch is separated by leaving the pitch containing the mesophase still.
In this case, there is a drawback that the composition of the pitch obtained is not constant.

In view of these circumstances, the present inventors conducted repeated machining efforts to obtain high-quality pitch for carbon materials, and as a result, they found that it is possible to produce high-quality mesophase pitch by using a specific material as the raw material oil. Based on these findings, the present invention was completed.

That is, the present invention deals with heavy oil having a boiling point of 200"C or more obtained by fluid catalytic cracking or thermal cracking of petroleum, and the residual fraction of product oil obtained by hydrotreating petroleum heavy oil. A method for producing a bit for a carbon material, which comprises heat-treating a mixture with a mixture of 550 and 450°C at a temperature of 550 to 450°C, and extracting a pitch containing substantially 100% mesophase from the obtained mesophase-containing pitch. .

There are various types of heavy oils with a boiling point of 200°C or higher obtained by fluid catalytic cracking or thermal cracking of petroleum, such as light oil, atmospheric residual oil, etc., in the presence of a silica/alumina catalyst or a zeolite catalyst. Among the products obtained by fluid catalytic cracking at 450-550°C, the boiling point range is 200-4.
5Q''C mold cost PO1 or by-products with a boiling point of 200°C or higher that are produced when producing ethylene etc. by thermally decomposing naphtha, kerosene, light oil, etc. together with steam at a temperature of 700 to 1000'C in a short time. There are heavy i+b, etc.

Next, the residual fraction of the product oil obtained by hydrotreating petroleum-based heavy oil, that is, bright stock, is produced by hydrotreating petroleum-based heavy oil such as vacuum light oil and deasphalted oil. It is a residual oil fraction obtained by distilling a product oil obtained by hydrolysis (either addition or hydrolysis) under reduced pressure, and the conditions of the hydrotreatment are not particularly limited.

When mixing the above Hl*'r''i'i, 1 is fluid catalytic cracking residual oil or thermal cracking residual oil?1
I (1o.

A suitable range is 5 to 100 parts by weight of prite stock, preferably 10 to 5 parts by weight. Bridestock acts as a modifier, so if it is used alone, a satisfactory pitch cannot be obtained.

The heat treatment of the raw material oil mixture is 350-45 o'C.

It is preferably carried out at a temperature of 680 to 420°C.

If the temperature is less than 55Q''C, it will take a long time to produce mesophase-containing pitch, and if it exceeds 45Q''C, coking will occur and the production of pitch will be hindered, which is not preferable. There are no particular restrictions on the heat treatment conditions except for the temperature, but the heat treatment is usually performed under normal pressure or reduced pressure for 5 to 20 hours, preferably under an inert gas atmosphere.

The pitch obtained by heat treatment is usually a mesophase pitch of 50~
It contains 80% by weight. In the present invention, pitch containing substantially 100% mesophase is separated from the mesophase-containing pitch.

There are various methods for separating, for example, at a temperature higher than the softening point of the mesophase-containing pitch, that is, from 280 to 380°.
A method of standing still for a predetermined period of time or centrifugation at a temperature of about 100 ℃ is suitable, and a method of separating using a solvent is also available.

The pitch obtained in this way has a softening point of about 260 to 270°C, which is significantly higher than that of general carbon materials such as carbon fiber pitch, which has a softening point of about 300 to 50°C. It is low. Therefore, the spinning process can be carried out at a low temperature, and there is almost no deterioration due to thermal decomposition polycondensation or the formation of bubbles or infusible substances during spinning, resulting in good spinnability.

Therefore, the pitch obtained by the method of the present invention is suitable as a raw material for carbon materials, especially carbon fibers, and when used as carbon fibers, it can be obtained that has both strength and elasticity. In addition to carbon fibers, this pitch can also be used as a base material for composite materials, and can also be used as electrodes, activated carbon, etc., and is expected to have a wide range of uses.

Next, let us explain the present invention to an example! Illll-explain.

The product obtained by fluid catalytic cracking of MW 1 vacuum gas oil with SOO''C in the presence of a zeolite catalyst is separated from the ζ residual oil (and β point 25Q''C or higher) by filtration. 100 parts by weight of the residual oil from which one product was removed and 100 parts by weight of the residual oil fraction (bright stock) obtained by hydrocracking vacuum gas oil and distilling it under reduced pressure were mixed. This mixture was heated at normal pressure under a nitrogen stream for 38 hours.
Q″C is 1 and time heat treatment is 1-. Then, 103Kg
A heat treatment was performed at 400° C. for 6 hours under reduced pressure to remove light particles and obtain mesophase-containing pitch.

The pitch thus obtained was placed in a container, left to stand at 580°C for 1 hour, and a portion of the pitch was taken out from the bottom of the container. The obtained pitch had a softening point of 260° C. and exhibited optical anisotropy as a whole.

Carbon fibers were then produced from this substantially 100% mesophase pitch. The mesophase pitch was melt-extruded at 290°C using a spinner with a nozzle diameter of 0.5τφ, and the winding speed was 5.
Melt spinning was carried out at 00 tn/min. During spinning for 5 minutes,
There were no yarn breaks and fibers with a uniform diameter were obtained. The fibers were then heated to 500''C in air at a heating rate of 1°C/min.
The carbon fibers were heated to a temperature of 100.degree. C., maintained at this temperature for 1 hour to make them infusible, and then fired at 1500.degree. C. for 20 minutes in an argon atmosphere to obtain carbon fibers with a thread diameter of 12 microns. The tensile strength of the obtained carbon fiber was 270 k17/tm2. Tensile modulus is 30t/
It was Fill+2.

Example 2 Same as Example 1 except that heavy oil by-product (boiling point 200°C or higher) obtained by steam cracking petroleum naphtha at 850°C was used in place of the fluidized catalytic cracking residual oil in Example 1. In the same manner, a pitch containing substantially 100% mesophase was obtained. The softening point of this pitch was 270°C.

Next, carbon fibers were produced according to Example 1 using the obtained pitch of 100% mesophase. The obtained carbon fiber has a tensile strength of 260 kg/1try+2. Tensile modulus 28t
Comparative Example 1 A pitch of substantially 100% mesophase was obtained in the same manner as in Actual LT, Example 1, except that only the fluidized catalytic cracking residue in Example 1 was used as the raw material. The softening point of this pitch is 50
It was 0°C.

Next, using the obtained pitch, the spinner 1U was heated to 54°C.
Carbon m-fibers were produced in the same manner as in Example 1 except for the steps in Example 1. The carbon fiber obtained here has a tensile strength of 210k.
g/throat2. The tensile modulus was 25t/k2.

Comparative Example 2 Pitch was produced in the same manner as in Example 1 except that only the above-mentioned hydrocracked residue fraction was used as the raw material. As a result, it was not possible to obtain a pinch of substantially 100% mesophase.

Patent applicant: Idemitsu Kosan Co., Ltd.

Claims (1)

[Claims] A mixture of heavy oil with a boiling point of 200°C or higher obtained by fluid catalytic cracking or thermal cracking of petroleum products and the residual oil fraction of the product oil obtained by hydrotreating petroleum heavy oil. 4
A method for producing pitch for a carbon material, which comprises heat-treating at a temperature of 50° C. and dividing heat into a pitch containing substantially 100% mesophase from the obtained mesophase-containing pitch.