JPS58142975A - Mesophase pitch and preparation of carbon fiber using it - Google Patents

Abstract

PURPOSE:To obtain carbon fibers having high strength and high modulus, by spinning mesophase pitch obtained by heating in an inert gas atmosphere at high temperature isotropic carbonaceous pitch prepared from an oil at a column bottom of the catalytic cracking product of petroleum fraction, making it infusible and carbonizing it. CONSTITUTION:Isotropic carbonaceous pitch obtained by distilling an oil at a column bottom (catalytic cracking bottom) formed by the catalytic cracking of a petroleum fraction (distilled oil of kerosine, etc., distillation residue, distillate prepared by subjecting crude oil or its fraction to hydrogenolysis, etc.) is heat- treated at 430-550 deg.C (preferably 450-510 deg.C) usually for 10sec-150min (preferably 2-100min) with introducing an intert gas (e.g., nitrogen etc.) in a rate of 200-5,000l/time/1kg raw material pitch into it, to give 40-100wt% mesophase (containing about 40wt% quinoline-soluble mesophase). This mesophase pitch is spun (at 300-450 deg.C at about 50-1,000m/min), made infusible (at 250-400 deg.C for about 5-60min) in an oxidative atmosphere, and carbonized (at 900-2,000 deg.C for about 0.5-30min), to give carbon fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to mesophase pitch and a method for producing carbon fiber using the same.According to the present invention, mesophase pitch containing quinoline-soluble menphase is extracted by It can be manufactured in a short heat treatment time without any special treatment, and the
Carbon fiber can be easily produced from Azubitsu.

The majority of commercially available carbon fibers are currently made from polyacrylonitrile fibers. However, these are extremely expensive because the raw material polyacrylonitrile fiber is expensive and the yield of carbon fiber obtained is low. On the other hand, a method using carbonaceous pitch as a raw material has attracted particular attention in recent years as a method for producing inexpensive carbon fibers because the raw material is inexpensive and the yield of carbon fibers is high.

Carbon bulk fibers obtained from optically isotropic pitch have low ferroelectric modulus and low elastic modulus. In order to obtain a linear fiber with high strength and high elastic modulus, it is necessary to heat-treat the #j1 isotropic pitch to form a mesophase, which is a type of liquid crystal. Such a mesophase is called a mesophase. The typical manufacturing method for meso 7A's bitch is, for example,
As described in Japanese Patent No. 1810, isotropic pitch is heated at 400° C. for 17 hours, thereby forming a mesophase of about 50 degrees. However, the mesophase #1 obtained by this method is entirely insoluble in quinoline or pyridine and is therefore difficult to spin due to the high softening point of the mesophase pitch.

In contrast, metsuphase pitch, which contains quinoline-soluble men-7Aze, has the advantage of being easier to spin due to its lower softening point, and research into high-performance carbon wire threads has been actively conducted in recent years. #i in the prior art regarding the production method of meso-7Aze pitch containing quinoline-soluble mesophase
There are the following.

In Japanese Patent Publication No. 54-160427, a quinoline-soluble mesophase is obtained by extracting isotropic pitch with a solvent and heating the insoluble molecules at 230 to 400°C. The inventor calls this neomesophase, and the solvent-insoluble fraction before heating is called the neomesophase-forming fraction (NMF fraction).

In Japanese Patent Application Laid-Open No. 55-58287, the pitch is set to 35 in advance.
The amount of NMF fraction is increased by heating at 0-480''C until just before the formation of menphase globules.

In JP-A-55-130809, the NMF fraction is increased by treating pitch with a dealkylation catalyst.

In JP-A-55-144087, after heat-treating pip, an organic solvent is added to remove suspended insoluble matter,
Further, an antisolvent is added to separate the NMF fraction by precipitation.

In Japanese Patent Application Laid-Open No. 56-2388, the pitch is set to 250 to 3.
After vacuum treatment at 80°C, heat treatment at 350-450°C under atmospheric pressure to remove the aromatic oil in the pitch, followed by extraction with a solvent to obtain the NMF fraction. I am getting .

In JP-A-56-109807, an organic solvent is added to pitch, heated to 350 to 450°C, insoluble matter is removed, and an antisolvent is added to obtain NMFlij.

In JP-A-56-167788, the boiling point is 200-5.
After removing the fraction with a boiling point of 400°C or less from the catalytic cracking bottom at 50°C, heat treatment is performed at 390 to 450°C, followed by removing oil at 320 to 380°C under reduced pressure, and further adding an organic solvent to remove insoluble matter. Then, an anti-solvent was added to obtain the NMFllii fraction.

In JP-A-57-2393, NMF fractions with different softening points are obtained by adding an antisolvent in multiple stages.

In Japanese Patent Application Laid-open No. 54-55625, the isotropic pitch is set to 3.
A heat treatment is performed at 80 to 430° C. with stirring while passing an inert gas through the mixture to obtain menphasic pitch containing pyridine-soluble mesophase. The heating time for this method is 2 to 60
It's time.

In JP-A-56-57881, mesophase pitch containing pyridine-soluble mesophase is obtained by subjecting pitch to physical operations such as solvent extraction.

In JP-A-56-101915, pitch precursors such as ethylene tar are heat-treated under pressure at 400 to 550°C, and then heat-treated under atmospheric pressure through an inert gas to produce a membrane containing pyridine 6-ethyl soluble memphase. I'm getting ace pitch.

In addition to these known techniques, pitch is reacted with tetrahydroquinoline at about 400°C and then heat-treated at about 500°C for a short time under reduced pressure to obtain an isotropic pitch called premenphase. A method for obtaining high-performance carbon fiber has been announced (Nihon Keizai Shimbun, August 22, 1981).

As described above, the known techniques have problems such as the need for special processing such as extraction to produce mesophase pitch, complicated processes, and long processing times.

The present inventors have discovered mesophase pitch from tower bottom oil produced by catalytic cracking of petroleum fractions, which is advantageous in commercial RC production, and a method for producing carbon fiber using the same, compared to the above-mentioned known technology. As a result of examining various processing conditions, we found that if the treatment is carried out under reduced pressure in a high-temperature chamber that has not been normally used, a low-softening agent containing quinoline-soluble menphase can be obtained without special treatment. It was discovered that a mesophase pitch leather of dots was obtained, and that the pitch could be easily spun as it was to form high-performance carbon fiber, and the present invention was completed.

In the first part #'i of the present invention, the mesophase pitch obtained by heating until an isotropic carbonaceous pitch obtained from the bottom oil produced by catalytic cracking of petroleum fraction is produced, in the second part. ,
Carbon characterized by spinning, infusible, and carbonizing isotropic carbonaceous pitch obtained from tower bottom oil produced by catalytic cracking of petroleum fractions, and menphasic pitch obtained by heating until solidification. A method for producing fibers is provided.

The menphase pitch of the present invention can be used in the production of carbon molded products such as films and sheets in addition to carbon fibers, and on the other hand, the carbon fibers can be used in high-performance reinforcing stones, fillers, and the like.

The raw material pitch used in the present invention is column bottom oil C (catalytic cracking bottoms) produced by catalytic cracking of petroleum fractions. Petroleum fractions here refer to distillate oils such as kerosene and light oil, distillation residues,
It refers to crude oil and the fractions produced by subjecting these fractions to treatments such as hydrocracking and hydrodesulfurization. For example, pitch or the like is used, which is obtained by removing the fraction having a boiling point of 450°C or less in terms of normal pressure from the catalytic cracking bottoms by distillation. Petroleum pitch obtained by appropriately treating the above-mentioned tower bottom oil may also be used. Commercially available petroleum pitches, such as Ashland 240 (
(manufactured by Ashland Fist Oil Co.) etc. can also be used.

The temperature range of the heat treatment used in the present invention is 430 to 55
0°C, preferably 440-530°C, especially 450°C
~510°C is preferred. Although it is possible to use a heat treatment temperature exceeding 550°C, mesophase pitch is formed in an extremely short period of time, and if the heat treatment is prolonged at this temperature, the quinoline-soluble portion of the mesophase pitch will rapidly decrease. This is not desirable as it makes it difficult to manufacture the carbon fibers used. On the contrary, the heat treatment temperature is 430℃
It is preferable to take a long time to generate the mesophase.
<No.

The time required for heat treatment varies depending on the raw material pitch, heat treatment temperature, etc., but is usually 10 seconds to 150 minutes, preferably #'i1
~120 minutes, particularly preferably tj2~! 00 minutes is used.

In the present invention, when performing the above heat treatment, it is performed while blowing an inert gas. As the inert gas, in addition to nitrogen and argon, hydrogen, methane, ethane, and other hydrocarbons that are gaseous at room temperature, hydrocarbons that are gaseous at least at the heat treatment temperature, steam, and the like are used. The amount of injection is 200 to 5,000 t per lb of raw material pitch for 7 hours, preferably 400 to 5,000 t per lb of raw material pitch.
3,000t/hour.

The mechanism by which the high-performance mesophase pitch of the present invention is obtained is not clear. However, it is necessary to heat at a specific heat treatment temperature while blowing inert gas, and high-performance menphase pitch cannot be produced by a method that only satisfies one of the conditions.

The present invention is preferably carried out while stirring the raw material pitch, but it is not essential.

Furthermore, in the present invention, the heat treatment is performed while blowing in the inert gas, but only the blowing of the inert gas is interrupted while the heat treatment is being performed! The heat treatment can also be continued by reducing the pressure in the -1 system.

Approximately 60% of the Men 7 Aes contained in Sofa's Bitch
4X or less, and contains about 40% or more of quinoline-soluble menphase relative to the menphase.

Here, the content of mesophase indicates the mesophase ratio at room temperature.

Furthermore, the mesophase pitch of the present invention usually has a softening point of 3.
00°C or less and can be easily spun.

The menphase pitch of the present invention can be spun by a known melt spinning method. Although the spinning temperature depends on the characteristics of the pitch, for example, 300 to 400°C is used. The spinning speed may be 200 to 1000 m/min or even higher, thereby obtaining pitch fibers of about 5 to about 15 μm. The pitch fiber is then heated under an oxidizing atmosphere such as an oxygen-containing gas, for example, at a temperature of 250 to 40
Infusibility treatment was performed at 0°C for about 5 to about 60 minutes, and nitrogen,
Under an inert gas atmosphere such as argon, for example, 900 to 20
Carbonization treatment is carried out at 00°C for about 0.5 to about 30 minutes. If desired, further under the inert gas atmosphere 2500 to 330
Graphite fibers can also be obtained by processing at 0°C. Further, in each of the above-mentioned processes, it is also possible to apply a known improvement method (for example, the method disclosed in Japanese Patent Laid-Open Nos. 55-6547 and 56-101916, etc.).

The present invention will be explained in more detail with reference to Examples below.

Example 1 From the catalytic cracking bottom, the boiling point in terms of normal pressure is 480 by distillation.
The fraction below ℃ was removed to obtain isotropic pitch. This pitch has a number average molecular weight of 373, a softening point of 85°C when observed under a microscope with a heating stage, and an elemental analysis value of C: 91.7%.
H: 5.9%, N: 0.2%, S: 1.5%.

This pitch 10f was placed in a reactor having an internal volume of 40 -, and immersed in a molten salt bath previously maintained at 490° C. under an argon atmosphere. After 4 minutes of soaking, the pitch reached about 485°C, so
1 at that warm temperature while blowing argon at 24 tons/hour.
Heat treatment was performed for 7 minutes. As a result, the yield of the heat-treated pitch produced was 33% by weight based on the raw material pitch, and the softening point was 2.
70℃, Menphase content 1j85%, JIS K
The quinorine soluble fraction tj determined by the 2425 centrifugation method was 44%.

Example 2 At the heat treatment pitch t400°C obtained in Example 1,
Melt spinning was carried out at 420 m/min using a spinneret with a hole diameter of 0.5 .mu.m. Subsequently, the temperature was raised to 270° C. over 3.5 hours in an air atmosphere, and the temperature was maintained at that temperature for 45 minutes to make it infusible. Further, carbon fibers were obtained by heating to 1000° C. at 5° C./min in an argon stream. The obtained fiber has a diameter of 12 μm
It showed anisotropy oriented in the axial direction when observed under a polarizing microscope.

In addition, the tensile strength is 186 [1 t/■, the modulus of elasticity is 1
It was 1000 noodles/■.

From the above actual examples, it is clear that mesophase pitch can be obtained by the method of the present invention and that high-performance carbon fiber can be manufactured using this.

Patent applicant Mitsubishi Yuka Co., Ltd. Agent Hidetoshi Furukawa Patent attorney Masahisa Hase Procedural amendment (voluntary) May 14, 1981 Old % 1 Haruki Shimada 1, Indication of the case 1982 Patent Application No. 24900 2 Title of the invention Mesophase pitch and method for producing carbon fiber using the same 3 Relationship to famous case for amendment Patent applicant address 2-5-2 Marunouchi, Chiyoda-ku, Tokyo Name (6)
05) Mitsubishi Yuka Co., Ltd. 4, Agent address: 2-5-2-5 Marunouchi, Chiyoda-ku, Tokyo Detailed description of the invention in the specification subject to amendment i Contents of amendment (1) Page 11, No. 2-5 Delete the 12th line and insert the following sentence.

[The mesophase hit obtained by the method of the present invention contains 40 to 100 mesophases, preferably 600 mesophases.
~100%, more preferably 70-100%.

In particular, if the content is less than 40%, the performance of the carbon fiber obtained from the pitch will be poor.Here, the menphase content was determined by one-light, one-microscope observation at room temperature, and Polarization m of a certain mesophase pitch
This indicates the ratio of the area occupied by the anisotropic portion in the view (including the isotropic portion and the anisotropic portion) to the total area. Further, the quinolinole dissolved content in the mesophase pitch is 60% or less, preferably 50% or less, preferably Yosho.
Fi is 40% or more. The spinnability of 4134 Tsuru Pituchi, which has a large proportion of quinoline dissolved matter, becomes poor. ” (2) No. x1! In the 3rd to 2nd lines at the end of the page, “300 to 400℃
'' should be corrected to ``300-450℃.''

(37 @ 11 Maki 2nd to 1st row [200 to 1000m/
[minute] should be corrected to [50-1000m/minute].

(4) Add the following Examples 3 to 8 after page 14, line 6.

[Examples 3 to 5 The heat treatment pitch was 4# Good in the same manner as in Example 1 except that the heat treatment conditions were as shown in Table 1. However, molten salt bath II! The temperature was about 5°C higher than the reaction temperature. The obtained results are as shown in Table 1.

(The following is a blank space) Examples 6 to 8 The heat-treated pitches obtained in rows 3 to 5 were melt-spun using a spinneret with a hole diameter of 0.5 m.

The spinning temperature and spinning speed were as shown in Table-2.

Table-2 ” that's all

Claims (4)

[Claims] (1) Mesophase pitch obtained by heating isotropic carbonaceous gas obtained from column bottom oil produced by catalytic cracking of petroleum fractions to an inert gas. (2) The menphase pitch according to claim 1, wherein the quinoline-soluble mesophase is about 40 times or more of the mesophase contained in the mesophase hit. (3) Isotropic carbonaceous pitch obtained from tower bottom oil produced by catalytic cracking of petroleum fractions is heated to -100% at a temperature range of 430 to 550°C, while blowing inert gas. A method for producing carbon fibers, in which meso7Aze pitch obtained by heating until mesophase is produced is spun, infusible, and carbonized to produce t4I mold. (4) The method according to claim 3, wherein the quinoline-soluble menphase accounts for about 40% or more of the mesophase contained in the mesophase hit.