JPS61289134A - Production of carbon yarn - Google Patents

Abstract

PURPOSE:To obtain pitch having a high softening point and improved spinning properties, by heat-treating at a specific temperature a heavy oil or pitch from which a primary quinoline-insoluble component is removed while introducing a gas containing oxygen with a lower oxygen concentration than that of air. CONSTITUTION:A solid component such as a primary quinoline-insoluble component, etc. is removed from a heavy oil or pitch, which is heat-treated at 100-400 deg.C, preferably about 300-400 deg.C while introducing a gas containing oxygen with a lower oxygen concentration (lower limit concentration is about 0.1%) than that of air. Isotropic pitch having >=200 deg.C softening point and 5-60wt% quinoline-insoluble content is obtained, easily made infusible after spinning is over and carbon yarn is easily obtained by treating the infusible pitch yarn with a hydrocarbon in the presence of an inert gas at 900-1,200 deg.C.

Description

[Detailed description of the invention] riō 11υ1 bon 1 The present invention relates to a new method for producing carbon fiber.

Definition of rg The terms used in this specification are defined below.

Heavy oil: A general term for petroleum-based and coal-based heavy oil.
Petroleum distillation residue, naphtha pyrolysis residue, ethylene bottom oil,
Examples include coal liquefied oil and coal tar.

Pitch: Refers to the heavy oil obtained by distilling the above-mentioned heavy oil to remove low-boiling components having a boiling point of less than 200°C.

Carbon IM... Fibers that have been infusible after spinning are (
(a) Carbonized, (b) Activated, and (
c) Including those subjected to carbonization treatment and activation treatment.

Of these, (b) and (c) are made porous by activation treatment and are also called activated carbon fibers.

The optically isotropic pitch used as a raw material for carbon fiber must not contain quinoline-soluble content (QI component), which is unfortunate and insoluble and thus inhibits the spinnability during spinning. First, it is necessary to have a high softening point so that the infusibility treatment after spinning can be carried out smoothly. Therefore, for example, JP-A-55-9891
In the method described in Publication No. 4, a nitro compound, quinoline, polycarboxylic acid, nido-O is added to heavy oil or pitch.
Heat treatment is performed by adding a softening point elevating agent such as benzene,
Obtaining pitch for spinning. However, with this method, the softening point of the spinning pitch obtained is still 160 to 2.
Since the temperature is in the low temperature range of about 00℃, the pitch atN after spinning is
The infusibility treatment takes a long time, resulting in poor productivity.

Means to Solve the Problem In view of the above-mentioned current situation, the inventor of the present invention has conducted various studies to improve the softening point of an optically isotropic pitch, and as a result, the present inventor has developed a heavy-weight material from which the QI component has been temporarily removed. When oil or pitch is heat-treated at a specific temperature while blowing a gas containing oxygen at a lower concentration than air, heat-treated pitch with a softening point of 200°C or higher can be obtained, and the pitch has excellent spinnability. We have discovered that the resulting spun fibers can be infusible at high temperatures within a short period of time.

That is, the present invention (1) (i) heat-treats the heavy oil or pitch from which the primary QI has been removed at 100 to 400° C. while blowing a gas containing oxygen at a lower concentration than air to lower the softening point. 20℃ or higher, isotropic Q1 component content 5-60%
(ii) spinning the obtained heat-treated pitch; (iii) infusibilizing the obtained spun pitch fibers; and (iv) carbonizing the infusible lIN thus obtained. The present invention relates to a method for producing carbon fiber characterized by comprising a step of (b) activation or (c) carbonization and activation.

It was completely unexpected that the heat-treated pitch obtained in the present invention has excellent spinnability even though it contains 5 to 60% of an isotropic QI component.

That is, as mentioned above, from the common knowledge of those skilled in the art that the isotropic QI component is incorrosive and insoluble and inhibits spinnability, it is natural that the isotropic QI acid component in the heat-treated pitch produced above has a similar inhibiting factor. This is because it is predicted that However, according to the research of the present inventor, the isotropic Qr acid component produced by heat treatment in the presence of oxygen is a polymer with a three-dimensional structure cross-linked and polymerized by oxygen molecules, and is fusible and flexible. It turned out to be molten. In other words, although this isotropic QI itself is a polymer, components other than QI (Q
Because it has the property of mutually dissolving (compatibility) with S component),
The two do not separate and exhibit uniform fluid-like behavior. Therefore, when heat-spinning the heat-treated pitch of the present invention,
The isotropic QI component does not pose an obstacle to spinning. Moreover, since the heat-treated pitch has a high softening point, the spun fibers can be easily rendered infusible.

In the present invention, solids such as primary QI components are removed from heavy oil or pitch as a starting material by means such as filtration, and then the heavy oil or pitch is blown with a gas containing oxygen at a lower concentration than air. Heat treatment is performed at about 100 to 400°C, more preferably at about 300 to 400°C. The lower limit of oxygen is approximately 0.1%. The amount of oxygen used varies depending on the heat treatment temperature and time, but usually heavy oil or pitch 1
The oxygen per ko is about 0.01 to 5 Q/min, more preferably about 0.1 to 3 Q/min. Heat treatment temperature is 10
If the temperature is less than 0°C, the polymerization reaction rate will decrease, which is undesirable, while if it exceeds 400°C, there is a risk of ignition or explosion, and excessive polymerization may occur.

In addition, in the heat treatment in the present invention, heavy oil or pitch is
This also includes the case where a gas having a lower M element concentration than air is blown in during distillation within the range of 0 to 400°C.

The isotropic QI component content m of the heat-treated pitch used for spinning is 5
~60%, and the softening point is 200°C or higher. When the content of the QI component is less than 5%, the softening point of the pitch is low, so it is necessary to lower the spinning temperature, and therefore the QI component does not melt and exists as a solid content. Therefore, troubles such as clogging of the spinning nozzle and yarn breakage can be avoided during spinning. On the other hand, if the QI component exceeds 60%, polymerization of a part of the pitch component has progressed too much, forming a solid content that is insoluble in heat, resulting in clogging of the spinning nozzle, yarn breakage, etc. This makes the spinning operation unstable.

The spinning operation of the heat-treated pitch is performed by the known melt extrusion spinning method,
This may be carried out in the same manner as the blow spinning method, centrifugal spinning method, etc. For example, when performing melt extrusion spinning, the heat-treated pitch described above is supplied to a spinning machine, heated to 300°C to 400°C, and extruded from a nozzle under pressure with inert gas to obtain a spinning pitch of ms*. Good.

The spun pitch m fibers can be infusible by a conventional method. That is, for example, at a temperature of 20°C in an oxidizing atmosphere.
Conditions of about 0° C. to 400° C. and holding time of about 1 to 3 hours are common, but it is also possible to adopt conditions other than these. Examples of oxidizing atmospheric gases include oxygen, oxygen-enriched air, and air, which can also cause deterioration of the working environment and machine V! A
If measures are taken against corrosion of the like, chlorine gas, NO gas, N02 gas, etc. may be added. In addition, the pressure of the oxidizing atmosphere is 0.2 ko/cm2
・0 or more, more preferably 1.0 klll/C meal 2
- By applying a pressure of 0 or more, the infusibility treatment time can be significantly shortened. In this case, although it varies depending on the properties of the heat-treated pitch, the thickness of the fibers of the spinning pitch, etc., under optimal conditions, it is possible to complete the infusibility treatment within an extremely short time of about one minute, for example.

The obtained infusible pitch fibers are subjected to (a) carbonization treatment, (b)
Subjected to activation treatment or (c) carbonization treatment and activation treatment.

When performing carbonization treatment, the temperature of the infusible pitch flIN is raised to about 20 to 1200 °C in the presence of an inert gas such as nitrogen gas, and held at the same temperature for about 10 to 30 minutes. Just do it. In this case, carbon fiber in a narrow sense is obtained.

When carrying out the activation treatment, the infusible pitch fibers are held in air at about 400 to 700°C, preferably about 500 to 600°C, for about 3 to 10 minutes, according to a conventional method, or
Or about 600-1000℃ in steam, preferably 70℃
It is sufficient to hold the temperature at about 0 to 900°C for about 5 to 120 minutes. In this case, porous activated carbon fibers having a specific surface area of about 500 to 2800 m2/Q are obtained.

When performing carbonization and activation, after carbonizing the infusible pitch till according to a conventional method under the same conditions as above,
All you have to do is activate it. In this case, 500 to 2800
Porous activated carbon fibers having a specific surface area of approximately m2/Q are obtained.

1 Ririshuo 1 (i) The obtained pitch has excellent spinnability.

(ii) Since the pitch has a high softening point, the infusibility treatment after spinning is easy.

(iii) Carbon fiber in the narrow sense is obtained by carbonizing the infusible pitch IIM at 900 to 1200'C in the presence of an inert gas.

(iv) By activating the infusible pitch fibers, activated carbon fibers having a specific surface area of about 500 to 2800 m2/Q can be obtained.

(V) By activating the carbon fibers in (iii) above, activated carbon fibers with a specific surface area of about 500 to 2800 m2/Q and higher strength can be obtained.

Examples will be shown below to further clarify the features of the present invention. In the following, all "%" refers to "% by weight".

Example 1 Coal tar was heated to 150°C and filtered under pressure using iP paper to remove the primary Q component in the coal tar. 1450
℃) to remove low boiling components.

The properties of the obtained pitch are as follows: softening point (Methocy method) -10
At 6°C, the QI component was -0%, and the 81 component was -16.7%.

Next, 500 g of the pitch obtained above was charged into a 1Q autoclave, and heat-treated at 380° C. for 70 minutes while stirring while blowing nitrogen gas containing 2% oxygen at a rate of 10 9 /min. The properties of the heat-treated pitch obtained were as follows: softening point (Methocy method) -262.4°C, QI component -15.5%, Bl component -
It was 72.2%.

Melt the heat-treated pitch obtained above! I temperature is 320℃ and diameter is 0.
Continuous spinning was performed from 31 nozzles at a winding speed of 600 m/min to obtain pitch aIte.

The pitch fibers were heated to 300° C. at a rate of 3° C./min in air, and then maintained at the same temperature for 2 hours to be infusible.

The infusible pitch IIM obtained above was heated at 50°C in a nitrogen atmosphere.
The temperature was raised at a rate of 1200° C. and maintained at 1200° C. for 5 minutes to obtain carbon fibers.

The average values of various properties measured for each of the 15 carbon fibers obtained were as follows.

Diameter: 10μm1 Tensile strength: 128 kQ/a+
i2, elastic modulus: 5.3 ton/am2, elongation: 2.
6%.

Example 2 Infusible pitch fibers obtained in the same manner as in Example 1 were activated with water vapor at 800° C. for 60 minutes.

The obtained activated carbon IIH has a specific surface area of 1530 m2/Q,
The pore volume is 0.68 WD/Q, and the benzene content is 0 per gram.
．． 55c+ was adsorbed. In addition, in the methylene blue desorption test according to JIS K1470, 240WtJ/
It was Q.

Comparative Example 1 Coal tar from which primary QI components were removed in the same manner as in Example 1 was distilled to remove low boiling point components with a boiling point of 550°C or lower, and the softening point (methosy method) was -198.6°C, QI
A pitch with properties of -2.8% component and 48.2% B2 acid component was obtained.

Next, the above pitch was heated to a diameter of 0.3H at a melting humidity of 243°C.
Pitch fibers were obtained by continuous spinning from a nozzle at a winding speed of 300 m/min. However, since the nozzle was severely clogged, a filter was installed in front of the nozzle to remove the QI component.

The resulting pitch fibers were heated at 200°C at a rate of 3°C/min in air.
After raising the temperature to
The temperature was raised to 0.degree. C. and maintained at the same temperature for 4 hours to perform infusibility treatment.

The thus obtained infusible pitch ljAM was heated at a rate of 50° C./min in a nitrogen atmosphere and held at 1200° C. for 5 minutes to form carbon IM. However, in the obtained carbon fiber, the filaments are partially fused together,
It was not possible to measure properties such as tensile strength.

(that's all)

Claims (1)

[Claims] (1) (i) While blowing gas containing oxygen at a lower concentration than air into the heavy oil or pitch from which the primary QI has been removed,
Softening point 200℃ by heat treatment at 00~400℃
As described above, a step of obtaining a pitch having an isotropic QI component content of 5 to 60%, (ii) a step of spinning the obtained heat-treated pitch,
(iii) a step of infusibilizing the obtained spun pitch fiber; and (iv) a step of (a) carbonizing, (b) activating, or (c) carbonizing and activating the obtained infusible fiber. Characteristic carbon fiber manufacturing method.