JPH09143822A - Treatment for making pitch fiber infusible - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treating method for making a pitch fiber infusible, capable of markedly reducing a time required for the treatment under an oxidizing atmosphere by adding quinones to a carbonaceous pitch and melt spinning. SOLUTION: This treating method for making a pitch fiber infusible, is to add 0.01-50wt.% quinones such as pyrenequinone and phenanthrene to a carbonaceous pitch capable of melt spinning, and melt spin it. It is possible to improve a productivity by reducing the time required for the following treatment for making the fiber infusible without adding any specific process.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for infusibilizing pitch fibers.

[0002]

2. Description of the Related Art A method for producing carbon fibers from pitch as a raw material can improve productivity if the treatment time in a heat treatment step such as infusibilization, carbonization or graphitization after spinning can be shortened and the productivity can be improved economically. Take an advantage. Until now, various catalysts or promoters have been studied in order to shorten the infusibilizing treatment time, but no satisfactory catalyst has been obtained from the viewpoint of the infusibilizing promoting effect.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pitch fiber infusibilizing method capable of significantly shortening the processing time of the infusibilizing step.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that when melt-spinning carbonaceous pitch, by adding quinones to carbonaceous pitch in advance, melt-spinning can be performed. The inventors have found that the processing time of the subsequent infusibilizing step can be significantly shortened and have reached the present invention. That is, the present invention relates to a method for infusibilizing pitch fibers, which comprises melt-spinning carbonaceous pitch to which quinones are added, and subjecting the resulting pitch fibers to infusibilization under an oxidizing gas atmosphere.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The type of carbonaceous pitch used in the present invention is not particularly limited as long as it can be melt-spun. As a specific example, coal-based pitch,
Petroleum pitch or naphthalene pitch, synthetic pitch such as polyvinyl chloride pitch, etc., and further modified pitches of these pitches, for example, those treated with a hydrogen donor such as tetralin, those hydrogenated under hydrogen pressure,
Examples include those modified by heat treatment, those modified by means such as solvent extraction, and those modified by appropriately combining these methods.

The carbonaceous pitch used in the present invention preferably has a softening point of usually 100 to 400 ° C., preferably 100 to 400 ° C.
Those at 300 ° C. are particularly preferable. The carbonaceous pitch may be either an optically isotropic pitch or an anisotropic pitch. In the present invention, the quinones are added to the carbonaceous pitch, melt-spun, and infusibilized. The quinones can be used without particular limitation as long as they do not volatilize at the temperature during melt spinning. As a specific example, anthraquinone,
Phenanthrenequinone, dianthraquinonyl, pyrenequinone, pyranthrone and the like can be mentioned. From the viewpoint of volatility, dianthraquinonyl, pyrenequinone, and phenanthrenequinone are preferable, and from the viewpoint of the effect of promoting infusibilization, pyrenequinone and phenanthrenequinone are particularly preferable.

In the case of pyrenequinone, it is not necessary to distinguish between the structural isomers, and for example, a mixture obtained by oxidizing pyrene with an oxidizing agent such as chromic acid can be used as it is. The amount of quinones added is usually 0.01 to 50 wt% with respect to the pitch, preferably 0.1 to 30 wt.
%, Most preferably 1 to 20 wt%. If the amount of quinones is too small, the effect of promoting infusibilization is small, and if the amount of quinones is too large, melt spinning becomes difficult. The carbonaceous pitch containing quinones can be melt-spun by a known method. The yarn diameter of the pitch fiber obtained is usually 5 to 10.
It is 0 μm, preferably 6 to 50 μm.

Next, infusibilizing treatment is performed in an oxidizing gas atmosphere. The infusibilization treatment is usually performed at 400 ° C. or lower, preferably 150 to 380 ° C., more preferably 20.
It is carried out at 0 to 350 ° C. If the treatment temperature is too low, the treatment time becomes long, and if the treatment temperature is too high, the phenomenon of fusion or consumption of the pitch fibers occurs, which is not preferable. Infusibilization time is usually 10 minutes to 5
The time is preferably 20 minutes to 2 hours. The temperature rising rate of the infusibilization treatment is usually 1 to 20 ° C./min, preferably 4 to 10 ° C.
/ Min.

The oxidizing gas is usually oxygen, ozone,
One, two or more kinds of oxidizing gases such as air, nitrogen oxides, halogen or sulfurous acid gas can be used. The pressure of the oxidizing gas is not particularly limited, but normal pressure is usually sufficient. The infusibilized pitch fiber can then be carbonized according to a known method in an atmosphere of an inert gas such as nitrogen, argon or helium to form a carbon fiber. The carbonization treatment is usually carried out at a temperature of 800 to 3500 ° C. and usually by firing for 1 second to 15 hours. Further, if necessary during the carbonization treatment, the object to be treated may be slightly loaded or tensioned for the purpose of preventing shrinkage or deformation.

[0010]

EFFECTS OF THE INVENTION According to the present invention, when melt-spinning a carbonaceous pitch, by adding quinones to the carbonaceous pitch in advance, the treatment time of the subsequent infusibilizing step can be performed without adding a special process. It can be significantly shortened. As described above, the method of the present invention can improve the efficiency of the infusibilization step with a technique that is industrially easily applicable.

[0011]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 A pitch fiber was obtained by adding 10 wt% of phenanthrenequinone to naphthalene pitch having an optical anisotropic phase content of 90 vol% and a softening point of 240 ° C., and melt spinning. After holding this pitch fiber in air at 100 ° C. for 60 minutes, the temperature was raised at a rate of 5 ° C./minute to complete infusibilization at 310 ° C. The time required for infusibilization was 2 hours in total. Then, at 1000 ° C. in an inert gas atmosphere, 5
When it was fired for an hour and then graphitized at 2500 ° C. for 1 hour, a carbon fiber having an elastic modulus of 840 GPa and a tensile strength of 3100 MPa was obtained.

Comparative Example 1 The pitch used in Example 1 was
Melt spinning was performed as it was without adding phenanthrenequinone to obtain pitch fibers. When the pitch fiber was heated at a rate of 5 ° C./minute, the fiber melted at the stage of 290 ° C. When the pitch fiber was held in air at 100 ° C. for 60 minutes and then heated at 1 ° C./minute, the infusibilization could be completed at 310 ° C. The time required for infusibilization was 5 hours in total, and the processing time was 2.5 times longer than that in Example 1. Then, the infusible fiber is treated under an inert gas atmosphere with 100
When baked at 0 ° C for 5 hours and then at 2500 ° C for 1 hour, the elastic modulus was 840 GPa and the tensile strength was 3100MP.
A carbon fiber of a was obtained.

(Example 2) An optical anisotropic phase of 85 vol was used.
%, And 10 wt% of pyrenequinone was added to coal tar pitch having a softening point of 270 ° C., and melt spinning was performed to obtain pitch fibers. This pitch fiber in air at 100 ℃
After holding for 60 minutes, the temperature was raised at a rate of 5 ° C / minute, and infusibilization was completed at 350 ° C. The time required for infusibilization was 2 hours and 10 minutes in total. Then, it is baked at 1000 ° C. for 5 hours in an inert gas atmosphere, and then at 2500 ° C. for 1 hour.
When fired for an hour, elastic modulus 810 GPa, tensile strength 2
A carbon fiber of 900 MPa was obtained.

Comparative Example 2 The pitch used in Example 2 was
Melt spinning was performed as it was without adding pyrenequinone to obtain pitch fibers. When the pitch fiber was held in air at 100 ° C. for 60 minutes and then heated at 5 ° C./minute, the temperature was 350 ° C.
The infusibilization was completed in. The time required for infusibilization was 5 hours 30 minutes in total, which was about 2.5 times longer than that in Example 2. Then, the infusible fiber is fired at 1000 ° C. for 5 hours in an inert gas atmosphere, and then 25
When baked at 00 ° C. for 1 hour, the elastic modulus was 805 GPa,
A carbon fiber having a tensile strength of 2900 MPa was obtained.

Example 3 Pitch fiber was obtained by adding 10 wt% of phenanthrenequinone to isotropic pitch having a softening point of 130 ° C. obtained by heating polyvinyl chloride to 410 ° C. and melt spinning. This pitch fiber 6 in air at 100 ℃
After holding for 0 minutes, the temperature was raised at a rate of 5 ° C./minute, and the temperature was 3
Even when the temperature reached 35 ° C., the infusibilization was completed without melting. The time required for infusibilization was 2 hours and 10 minutes in total. After that, baking is performed at 1000 ° C. for 5 hours in an inert gas atmosphere, and then 25
When fired at 00 ° C. for 1 hour, carbon fibers having an elastic modulus of 15 GPa and a tensile strength of 1200 MPa were obtained.

Comparative Example 3 The pitch used in Example 3 was
Melt spinning was performed as it was without adding phenanthrenequinone to obtain pitch fibers. When this pitch fiber was held in air at 100 ° C. for 60 minutes and then heated at a rate of 5 ° C./minute, the fiber melted at the stage of 200 ° C. Also, after holding the pitch fiber in air at 100 ° C. for 60 minutes, 1 ° C. /
When the temperature was raised in minutes, the infusibilization could be completed at 335 ° C. The time required for infusibilization was 5 hours and 10 minutes in total, and the infusibilization time was about 2.4 times longer than that in Example 2. Then, it was fired in an inert gas atmosphere at 1000 ° C. for 5 hours and then at 2500 ° C. for 1 hour to obtain carbon fibers having an elastic modulus of 14 GPa and a tensile strength of 1100 MPa.

Claims (1)

[Claims] 1. A method of infusibilizing pitch fibers, which comprises melt-spinning carbonaceous pitch to which quinones are added, and subjecting the obtained pitch fibers to infusibilization in an oxidizing gas atmosphere.