JPS6257932A - Production of carbon fiber and graphite fiber - Google Patents

Abstract

PURPOSE:To produce the titled fiber having excellent handleability and high tenacity and modulus, free from tenacity unevenness of yarn, by winding a doubled pitch fiber on a bobbin and subjecting the fiber to plural heat-treatment steps under specific condition in a state wound on the bobbin. CONSTITUTION:A doubled pitch fiber produced by the melt-spinning of optically anisotropic carbonaceous pitch is wound on a gas-permeable bobbin, infusibilized in an oxidizing atmosphere in a state wound on the bobbin and subjected to the first heat-treatment in a non-oxidizing atmosphere at <=690 deg.C (preferably 500-550 deg.C). The treated fiber is subjected to the second heat-treatment in an inert gas atmosphere at >=1000 deg.C (preferably 1000-3000 deg.C) to obtain the objective fiber. The second heat-treatment is preferably carried out in a state wound on the permeable bobbin or by unwinding the doubled pitch fiber from the bobbin and transferring the yarn at a speed of e.g. 0.5-20 m/min.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing carbon fibers and graphite fibers from carbonaceous pitch fibers. More specifically, the present invention involves spinning optically anisotropic carbonaceous pitch, performing infusibility, carbonization, and graphitization to obtain long filament carbon fibers.
This invention relates to a method for firing pitch fibers.

(Prior art) There has been a demand for the development of high-performance materials with properties such as light weight, high strength, and high modulus of elasticity in a wide range of technical fields related to automobiles, aircraft, and various other industrial fields. Carbon fiber or molded carbon materials are attracting attention. Especially carbon fiber from carbonaceous pitch! ! ! The way to build is
This method is attracting much attention as a method for producing low-cost, high-performance carbon fiber.

However, depending on the conventional technology, pitch fibers have a low tensile strength of about 0.01 GPa and are brittle, making them difficult to handle, and it is difficult to obtain long filament fibers necessary to obtain straight products. It was extremely difficult.

Conventionally, as a method for producing long filament-shaped charcoal-2 fibers from pitch fibers, the spun yarn is dropped into a wire mesh basket and deposited, and the wire mesh is made infusible and heated at temperatures above 700°C. After performing the first heat treatment so that the tensile strength of the yarn is 0.2 GPa or more, it is carbonized at a temperature of about 1500°C after being pulled up from the basket and wound up, or while being wound up. , a method for obtaining carbon fiber has been proposed (Japanese Patent Publication No. 12740/1983).

However, in this method, when the yarn is deposited,
It has a tendency to twist or smolder, and is prone to paternal bending. Therefore, when it is made into carbon fiber, it becomes a thread with extremely uneven appearance, and the strength of the bent part is seriously reduced, resulting in frequent thread breakage. The drawback was that it was difficult to produce high-quality thread. These drawbacks cannot be essentially improved even if the curvature is increased when the threads are piled up.

On the other hand, Japanese Patent Publication No. 53-4128 discloses that mesoface pinch is melt-spun, wound once around a bobbin, some of the threads are placed in a net tray, and oxidized at 250°C to 500°C. A method is disclosed in which the yarn is oxidized in an atmosphere to increase the strength of the yarn, making it easier to handle the yarn, and then processing the yarn. However, this method
The oxidation process is carried out in an oxidizing atmosphere and in a temperature range of The disadvantage was that production efficiency was low because

In addition, JP-A No. 55-128020 discloses that after melt spinning, the yarn drawn with a godet roller is continuously passed through a hot blast furnace for infusibility at a yarn speed of 0.15 m/min, and then passed through a carbonization furnace. A method for obtaining carbon fibers by continuous threading is disclosed. However, while this method can produce yarn with a good appearance when made into carbon fibers, it has the disadvantage that the product output per hour is extremely small.

(Problems to be solved by the invention) Japanese Patent Application No. 59-27679J+, Japanese Unexamined Patent Publication No. 60-81320
No. and Japanese Patent Application Laid-open No. 60-21911 discloses that the bobbin is made infusible as it is, and the
A method for carrying out the following heat treatment (pre-carbonization) is disclosed.

However, in these methods, when the winding thickness of the pitch fibers of Bobite stone becomes It, the air permeability during infusibility or pre-carbonization is insufficient, resulting in fusion or agglutination between the filaments,8 and After carbonization, it becomes difficult to unwind (unwind) the thread on the bobbin, and when unwinding it, the thread tends to become fluffy, which has the disadvantage of significantly reducing the commercial value when made into carbon fiber or black i0 fiber. .

Furthermore, due to insufficient air permeability, there is a large variation in the degree of infusibility, and when carbon fibers or graphite fibers are made, the strength variation is extremely large.

Therefore, there is a strong need for a method to inexpensively and efficiently produce long filaments of pitch yarn carbon fibers that have a good appearance and less fuzz when handled, and have high strength, high elasticity, and uniform yarn strength. Ta.

The object of the present invention is to solve the above-mentioned drawbacks of the conventional technology and provide a method for producing pitch yarn carbon fibers that are easy to handle and have high quality.

Another object of the present invention is to provide a method for efficiently producing high-quality pitch yarn long filament carbon fibers that have a good appearance, high strength, and high elastic modulus.

(Means for Solving the Problems) According to the present invention, optically anisotropic carbonaceous pitch is melt-spun, the spun pitch fibers are wound onto an air permeable bobbin after doubling, and the bobbin-wound fibers are wound as they are. After being infusible in an oxidizing atmosphere, a first heat treatment is performed in a non-oxidizing atmosphere at a temperature of 690°C or lower, and then the material is left wound on a breathable bobbin in an inert gas atmosphere at a temperature of 1,000°C or higher, or This was achieved by winding the yarn while feeding it and performing a second heat treatment.

a) Optically anisotropic carbonaceous pitch The optically anisotropic carbonaceous pitch used in the present invention is produced by polishing the cross section of a pitch lump solidified at room temperature, and rotating orthogonal nicols with a reflection-type changing microscope. In other words, pitches in which most of the pitches are optically anisotropic, and pitches in which no brilliance is observed and are optically isotropic are considered to be optically isotropic in unknown details. This is called a directional carbonaceous pinch. Therefore, in the optically anisotropic carbonaceous pinch in unknown my, not only the pure optically anisotropic carbonaceous pitch but also the optically isotropic phase in the optically anisotropic phase has a spherical or amorphous shape. This also includes cases where it is included in an island shape.

Also, the case of substantially optical anisotropy means that optically anisotropic carbonaceous pitch and optically isotropic carbonaceous pitch coexist, but because the amount of optically isotropic pitch is small, This is a case where the optically isotropic phase (hereinafter referred to as IP) cannot be observed depending on the polarizing microscope described above, and only the optically anisotropic phase (hereinafter referred to as AP) is observed. Incidentally, in general, AP
A clear boundary is observed between IP and IP.

The AP in unknown my is considered to be the same as the "meso phase" in place III#, but the "meso phase" includes a component that is substantially insoluble in quinoline or pyridine, and a component that is soluble in quinoline or pyridine. There are two tits, and AP in animals of unknown class is mainly the "mesophase" of the latter.

The above AP phase and IP phase are thick not only in optical properties but also in viscosity (because they are different, it is generally undesirable to spin a pitch in which both are mixed, as it may cause yarn breakage or uneven yarn thickness. This means that even if the optically isotropic pitch does not contain foreign substances that are undesirable for spinning,
This means that particularly bad results occur if the IP phase is not homogeneously dispersed within the AP phase. Therefore, the optical anisotropic pitch used in the present invention is required to have substantial homogeneity. Such a homogeneous optically anisotropic pitch is I
The P content is 20% or less, solid particles with a particle size of 1 μm or more cannot be detected in the cross section of the pitch by reflection microscope observation, and there is substantially no foaming due to volatile matter at the melt spinning temperature.

In the present invention, the quantification of AP and IP is performed by observing under a polarizing microscope with crossed Nicols, and taking a photograph to quantify AP or IP.
This is done by measuring the area ratio occupied by the area, but statistically this area ratio actually represents the volume %. % and electric power % can be treated as being equal.

The optically anisotropic pitch used in the present invention is not particularly limited, but preferably has a low softening point.

Here, the softening point of the pitch is the transition temperature between the solid phase and the liquid phase of the pitch, and the pitch softening point is the transition temperature between the solid phase and the liquid phase of the pitch. ! ) It can be determined from the peak temperature at which latent heat is absorbed or released when pitch is melted or solidified using a positioning needle. The softening point measured by this method agrees within a range of ±10° C. with the temperature obtained by other measurement methods such as the ring and ball method and the micro melting point method.

Ordinary spinning techniques can be used for spinning in the present invention. Generally, the spinning temperature suitable for melt spinning is 60°C to 100°C higher than the softening point of the material to be spun. On the other hand, the optical anisotropy pinch used in the present invention is 380
If the temperature is higher than 0.degree. C., thermal decomposition polycondensation may occur and decomposition gas may be generated or unmelted substances may be produced. Therefore, the softening point of the optically anisotropic pitch used in the present invention is preferably 320°C or lower, and the softening point of the optically anisotropic pitch used in the present invention is preferably 320°C or lower, and the
The temperature is preferably 30°C or higher.

The constituent components of the optically anisotropic pitch used in the present invention can be divided into n-hebutane soluble, heptane insoluble, benzene insoluble, and quinoline soluble as follows. That is, powdered pitch was placed in a cylindrical filter having an average pore size of 1 μm, and heat extracted with n-hebutane using a Soxhlet extractor for 20 hours, and the soluble content was determined to be the n-hebutane soluble content, and the insoluble content was The remainder is determined as n-hebutane insoluble matter. Next, remove the above insoluble matter with benzene for 20
The insoluble residue obtained by time-heat extraction is defined as the benzene insoluble matter. On the other hand, a quinoline soluble content can be obtained by measuring the insoluble content of powdered pitch using a centrifugal separation method based on JIS-2425 using quinoline as a solvent. Furthermore, the benzene-insoluble and quinoline-soluble component can be determined by subtracting the quinoline-soluble content from the benzene-insoluble content measured above. Such fractional quantification of constituent components is described, for example, in Journal of the Japan Petroleum Institute, Vol. 20, No. 1, p. 45 (1977).
This can be carried out by the method described in .

b) Method for producing optically anisotropic pitch The optically anisotropic pitch used in the present invention may be produced using any production method, but it may be produced by using a common raw material for pitch production, such as a hard hydrocarbon oil, A conventional method is used in which tar, commercially available pitch, etc. are stirred in a reaction tank at a temperature of 380°C to 500°C, and thoroughly thermally decomposed while degassing with an inert gas to increase the AP of the residual pitch. be able to. However, when a product with an AP content of 80% or more is produced by this method, the thermal decomposition polycondensation reaction proceeds too much, the quinoline solubility increases to 70% or more, and the softening point also increases to 3.
Not only can the temperature be 30° C. or higher, but also IP is difficult to form a microspherical dispersed state, so it is not necessarily a preferable method.

Therefore, a preferred method for producing the optically anisotropic pitch used in the present invention is to terminate the pyrolysis polycondensation reaction halfway and hold the polycondensed metal at a temperature in the range of 350°C to 400°C to substantially This is a method in which AP with a high density is left to stand still in the lower layer while growing and ripening, and this is separated from the upper layer where there is a large amount of IP with a lower density. It is described in No. 111.

A more preferable method for producing the optically anisotropic pitch used in the present invention is to use a carbonaceous material that contains an appropriate amount of AP and is not yet excessively utilizable, as described in JP-A-58-180585. In this method, the pitch is centrifuged in a molten state to rapidly sediment the AP portion. According to this method, the AP phase coalesces and accumulates in the lower I- (l1li in the direction of centrifugal force), forming a continuous I- with about 80% or more of AP, and a slight stripe of IP in it. The pinches in the form of spherical or minute spherical bodies form the lower layer, while the upper layer I
- is a pinch in which IP is the majority, and AP is dispersed therein in the form of minute spheres. In this case, jljf−
The boundaries between the two layers are clear, and only the lower layer can be separated and taken out from the upper layer, making it possible to produce optically anisotropic pitch that has a large AP content and is easy to spin. According to this method, when the AP content is 95% or more, the softening point is 230.
C. to 320-C carbonaceous pitch can be obtained economically in a short time. Such optically anisotropic carbonaceous pitch has excellent melt-spinning processing properties, and due to its homogeneity and high orientation, it can be spun to improve the tensile strength and elasticity of the resulting carbon fibers and graphite fibers. The rate is extremely good.

C) Manufacture of fibers i) Spinning The above pitch having a high AP content and a low softening point can be spun by known methods. Such a method can be used, for example, to
．． Pitch was placed in a metal spinning container with a spinneret of 1 mm to 0.5 mm, and the pitch was heated to 280 mm under an inert gas atmosphere.
The pinch is held at a constant temperature between ~370°C, kept in a molten state, and the pressure of the inert gas is increased to several hundred mmHH to push the molten pitch out of the nozzle, and the pitch flows down while controlling the temperature and atmosphere. The fiber is wound onto a bobbin that rotates at high speed.

In the present invention, uniform unwinding (
In order to perform S return), the traverse during spinning is 2 to 100
The thickness of one winding is 1 to 100 mm, preferably 5 mm/(per bobbin rotation).
It is effective to set the distance to 50 mm. The traverse is 5, considering the unwinding (unwinding) of the pitch fiber from the bobbin.
Approximately 20 mm/(one rotation of the bobbin) is preferable.

It is also possible to adopt a method in which pitch fibers spun from a spinneret are collected in a can-like manner in a lower collecting case while being collected by an air current.

In this case, continuous spinning is possible by supplying pitch to the spinning container under pressure using pre-melted pitch or a gear pump or the like.

Furthermore, in the above method, it is also possible to use a method in which the pitch fibers are drawn and drawn using gas that is controlled at a constant temperature and descends at high speed in the vicinity of the die, and long fibers are produced on the belt conveyor below. .

Furthermore, a cylindrical spinning container having a spinneret on the peripheral wall is rotated at high speed, molten pitch is continuously supplied to the spinning container, and the pinch is pushed out from the peripheral wall of the cylindrical spinning device by a drawing force, and the spinning is performed by the action of rotation. It is also possible to adopt a spinning method that accumulates pitch fibers.

Furthermore, in the present invention, even when spinning by any known method, optical anisotropy with a low softening point of 280°C to 370°C is achieved despite the AP content being as high as 95% or more. Since carbonaceous pitch is used at a temperature of 1°, spinning can be performed at a lower temperature than before. When spinning at such temperatures, thermal decomposition and thermal aggregation are kept to a very low level, so that the spun pinch fibers can maintain almost the same chemical composition as the pitch before spinning. Therefore, the fibers after spinning can be melted and freshly spun, which is advantageous.

if) Pitch fiber and yarn of A1 In the present invention, in order to increase the air permeability of the pinched fiber on the bobbin, the pitch fiber is wound around the infusible bobbin. Perform doubling at +1.

Melt spinning #R The number of filaments of pitch fiber spun from one machine (one spinneret) is limited due to melt spinning, and the number of filaments is 1 to 2,000, preferably 50 to 1.0.
00 filament.

In the present invention, 2 to 20 pitch fibers obtained by melt spinning are used.
200 to 50,000, preferably 500 to 5
,000 filaments.

Traverse during doubling is 5 to 100 mm per bobbin rotation
It is preferable that 0. In order to have good air permeability, it is better to make the traverse large, but if it is too large, it is not preferable because the thread is easily damaged.

Pitch fibers dropped into cans may be pulled up from a plurality of baskets or cases and spliced.

Doubling is not only done by unwinding from a bobbin (it is also possible to bundle pitch fibers spun simultaneously from a plurality of spinning machines or spinnerets and doubling them).

You may combine 2 to 20 yarns at a time, but 2 to 10 yarns may be combined at a time.
A method is also used in which the books are first doubled and then 2 to 10 pieces are recombined each time.

As the number of filaments of the pitch fibers increases, the air permeability improves, and the reaction of infusibility and pre-carbonization proceeds more uniformly, so the winding thickness can be increased.

The winding thickness after doubling is usually 1 to 100 mm, preferably 5 to 100 mm.
If the thickness of 6 turns (59 mm) is too thick, heat will accumulate and the reaction will proceed unevenly, causing fusion and sticking between filaments, causing variations in the strength of the filaments, and making it impossible to obtain high quality filaments. Undesirable.

In the present invention, since infusibility and carbonization are performed while winding the bobbin, it is necessary to select a material for the bobbin that can withstand these temperatures. In the present invention, in addition to metal bobbins such as iron, copper, nickel, and other alloys, carbon/
Ceramic bobbins such as carbon fiber composites, graphite composites, silica/alumina can be used, but in particular stainless steels such as 5US304.5US316,
Carbon steel, brass, etc. can be preferably used.

When heat treatment is performed at 1000℃ or higher while the bobbin is still wound, at least the outer surface of the bobbin must be compatible with carbon fiber, absorbing the shrinkage of the fibers that occurs during the heat treatment, and preventing the fibers from being cut. It is preferable to coat it with a material (for example, a carbon material) that can be used.

The entire outer surface of the bobbin can also be covered with a material that is both elastic and breathable, such as carbon felt.

In the present invention, the bobbin used for doubling is cylindrical, and may be made of wire mesh to improve ventilation, or may be made with holes or porous material such as sintered metal furnace material or sintered glass. .

When making holes, it is preferable to set the void ratio (opening ratio) to 10 to 80%.If the void ratio is 80% or more, the strength of the bobbin will decrease, so it is not preferable,
If it is below, the air permeability will be insufficient and the firing during infusibility and carbonization will be uneven, which is undesirable.Also, for uniform firing, it is preferable to reduce the heat capacity of the bobbin, so the wall thickness of the bobbin should be 5 mm or less. In the present invention, it is preferable to use a bobbin with a wire mesh layer of SUS 304 or 5US316, and the wire mesh has a thickness of 2 to 30.
0 mesh, preferably 3 to 60 mesh.

In the present invention, the melt-spun pitch fibers are bundled through an air sucker and then guided to an oiling roller where a sizing agent (oil agent) is applied and further bundled.

In this case, examples of the sizing agent include ethyl alcohol,
Alcohols such as isopropyl alcohol, n-propyl alcohol, butyl alcohol or viscosity 3-300c
Dimethyl silicone oil, methylphenyl silicone oil, etc. at (30℃) diluted with a solvent such as silicone oil or paraffin oil, or dispersed in water with an emulsifier added; Similarly, graphite, polyethylene glycol, or hindered Among the various oils used for other ordinary fibers such as polyester fibers, those that do not damage pinched fibers can be used. Fiber of sizing agent/＼ accompaniment usually 0.01-10%
However, 0.05 to 5% is particularly preferred.

iii) Bifuchi tJ made from infusible spun pitch fibers! In the process of oxidizing i-fibers to make them into infusible carbon JR wire fibers, it is necessary to consider various combinations of temperature, oxidizing agent, reaction time, etc. In the present invention, basically, the conditions for infusibility are as follows: Although known methods can be used, in the present invention, since pinch yarns with a large degree of accumulation are infusible on the bobbin, the oxidation reaction starts at a lower temperature than usual to prevent fusing and crimping of the pitch fibers. The temperature of the infusibility step in the present invention is 1 which needs to be prevented.
The temperature is raised stepwise or gradually in the range of 50°C to 400°C, preferably 200°C to 300°C, and the treatment is usually carried out for 1 to 5 hours. The treatment time may be 1 to 3 days so that the infusibility reaction proceeds sufficiently and uniformly.

Infusibility can be achieved using air, oxygen, or a mixed gas of air and oxygen or nitrogen, but it is not preferable to make the oxygen concentration too high because the reaction within the bobbin spool will proceed rapidly and there is a risk of combustion. .

In the present invention, halogen and N
Sufficient infusibility can be obtained by treatment for a short time in an atmosphere containing an oxidizing agent such as O2 or ozone, or at a temperature 30 to 50 degrees Celsius lower than the softening point of pitch, i.e., at a temperature of 150 to 240 degrees Celsius, in an oxygen gas atmosphere. It is preferable to maintain the temperature for 10 minutes to 1 hour until the temperature is obtained, and then raise the temperature to about 300°C if necessary to complete the infusibility. The method of & is preferred because it is easy and reliable.

In the present invention, a method is adopted in which the pitch is left in air at a temperature of 150 to 250°C for a long time depending on the softening point of the pitch, and then the temperature is raised to 300°C to 400°C for a short time without using an oxidizing agent. You can also do it. In particular, when carbonaceous pitch having a softening point of 280°C or higher is used, it is preferable to hold it at a temperature of 230 to 250°C for about 30 minutes to 2 hours to make it infusible.

In the present invention, the infusibility is carried out while winding the bobbin, so if a sizing agent is used during spinning, the water and low boiling point oil in the sizing agent are evaporated and removed before the infusibility treatment. It is necessary to improve ventilation. Such pretreatment can reduce unevenness in the infusibility treatment.

For infusibility, it is preferable to replace the old gas by circulating fresh gas of the same type as the atmosphere at a rate of 0.1 to 3 times per minute.The gas replacement is performed using a cylindrical breathable bobbin This can be done efficiently by blowing the replacing gas into the center of the tank.

The atmosphere during the infusibility treatment is preferably forcibly stirred by a fan, and the wind speed is 0.1 to 10 m/sec, preferably 0.5 to 5 m/sec.

Such forced stirring promotes gas penetration into the bobbin,
This has the effect of eliminating temperature distribution within the infusibility furnace and making firing uniform.

iv) Heat treatment step The first heat treatment in the present invention is performed at 400°C to 1000°C.
It causes carbonization in the preliminary stage or very early stage of carbonization of carbonaceous fibers that occurs in the temperature range of .degree. Of course, this process can be performed completely separately from the infusibility process, but after the infusibility process is complete, the gas in the furnace is removed to create a vacuum, or the furnace is left in a vacuum, or nitrogen gas or argon gas is used. Alternatively, an inert gas such as the like may be introduced.

The elongation of the first heat treatment system is highest at 3 to 7% when the heat treatment temperature is around 500℃, and is only about 2% at 700℃, so the first heat treatment should be performed at a temperature of about 500℃. is preferable, and in this case, the tensile strength is 0.1 to 0,
#JA fibers of 5 GPa can be easily obtained without cutting.

When the above heat treatment is performed in the presence of an inert gas, partial replacement of the gas, ventilation inside the bobbin, etc., as in the case of infusibility treatment,
It is preferable to perform forced ventilation of the atmosphere using a fan.

When the second heat treatment of the present invention is performed at about 1000°C to 1900°C, so-called carbon fibers are obtained, but when this heat treatment is performed particularly at 2000°C to 3000°C, so-called graphite fibers are obtained. I can do it.

The second heat treatment is performed by unwinding the carbonized yarn obtained by the first heat treatment, further doubling if necessary, and winding it on an air-permeable bobbin, or at a rate of 0.1 to 50 m/min, preferably. 0
．． It is carried out while being fed out and wound up at a speed of 5 to 20 m/min.

The second heat treatment is preferably carried out in the presence of an inert gas such as nitrogen gas and/or argon gas, and the same gas is blown into the furnace core tube, and it is preferably carried out while partially displacing the gas, especially for the production of graphite fibers. In this case, it is most preferable to use argon gas as the inert gas.

The second heat treatment step can be performed while applying tension to the yarn, if necessary.

(Effects of the Invention) Since the method of the present invention significantly improves air permeability, even when pinch fibers are wound thickly on a bobbin, uniform infusibility and pre-carbonization are possible, and fusion between filaments can be prevented. High quality long filament yarn can be obtained without producing 11 pieces.

In addition, the present invention not only allows optically anisotropic carbonaceous fibers to be thermally hardened while being wound around a bobbin after doubling, and then to be unwound and carbonized or graphitized. Alternatively, since it can be graphitized, production efficiency is extremely high, and charcoal with high strength and high modulus of elasticity can be obtained efficiently. Further, by completing the second high-temperature heat treatment in a very short time, graphite fibers with high strength and high modulus of elasticity can be easily obtained. The fibers obtained in this way are high-quality long filament yarns that have little fuzz when handled and have a good appearance.They are not only windable, unwindable, and doubled, but can also be used for textiles. It can also be made into a knitted fabric, and can be used for filament winding in the production of composite materials, prepreg production, etc., so the scope of its application is wide and the significance of the present invention is great.

EXAMPLES The present invention will be explained in detail below using Examples, but the present invention is not limited thereto.

(Example) Example 1 A carbonaceous pitch containing about 5594i of optically anisotropic phase (A13) and having a softening point of 232° C. was used as a precursor pitch. This precursor pitch has a quinoline solubility of 16
．． It contained 1% ash, 26g% ash, and a viscosity of 2.8 voids at 370'C. This bisona was melted in a melting tank with a content of 4W2OP, and the temperature was controlled at 370°C, and the effective volume inside the rotor was 200r.
NL cylindrical continuous centrifugal separator; send 20 m 17 minutes of crude oil to NL, control the rotor temperature at 370°C, and apply a centrifugal force of 30,000 G to a pitch with more optically anisotropic phase than AP discharge 1 (A pitch) and ζtU were continuously ejected from the IP outlet with a pitch (I pitch) with more optical isotropy.

The optically anisotropic pitch of 11 makes the optically anisotropic phase 9
Contains 8%, softening point 265℃, quinoline solubility 29.5
! It was 16.

Next, the obtained optical anisotropy 1! l: Pitch, melt spinning with 500 large spinnerets (1 nozzle hole; diameter 0
, 3 + n + n), and pass through 355° (about 2
fl O+nm If IT extrusion with nitrogen gas pressure 7
ji't installed on the nozzle m++ and rotating at high speed.
It was wound onto a wire mesh bobbin made of stainless steel with a hanging length of 210 m, ml, 1%%, and 200 nm, and spun for 10 minutes at a winding speed of about 5 UUm/min. The traverse pitch per one revolution of the bobbin was 1 (l m nt / 1 revolution. There was no yarn breakage during spinning. At this time, the spun yarn was approximately converged by an air sucker and guided to the ζ oiling roller, and the yarn was The focusing oil was supplied at a ratio of about 0.5% to the oil.The oil C had a viscosity of 14 c
s.t. dimethyl silicone oil was used.

Six bobbins wound with pitch fibers were combined with a traverse pitch of 20 mm/rotation, and 3,000 filaments were wound onto a stainless steel wire mesh bobbin of IIO mesh (void ratio 55%). The winding thickness of the thread in this case was about IQrtzn.

In this way, the wire mesh bobbin-wound pitch fibers were introduced into a fan-equipped forced hot air (shield ring furnace) in an air atmosphere.The temperature was increased from 150°C to 230'C by 0.5°C/min The temperature was raised at a speed of 250° and held for 22 hours. During this time, the atmosphere in the furnace was replaced with fresh air at a rate of 0.5 times/min. The stirring air speed in this case was 0.7 m/sec. there were.

After the infusibility treatment was completed, the inside of the furnace was made into an IF vacuum, replaced with nitrogen gas, and the temperature was raised to 500° C. at a rate of 5° C./min to perform a first heat treatment. In this case, the atmosphere in the furnace was replaced with fresh nitrogen gas at a rate of 0.1 times per minute. Further, the atmosphere was stirred at O and at a wind speed of 1 m/sec.

After the first heat treatment was completed, it was cooled to 300° C. in 1 hour and taken out. The carbonized yarn thus obtained was flexible and could be easily rewound.

It was also easy to combine 6 bundles of yarn consisting of 3,000 filaments. The tensile strength of this thread is 0.2
0 Pa, lljl weight ratio to pa, elongation is 5.2
%Met.

The first heat treatment system was sent to a carbonization furnace at 1500°C in a nitrogen gas atmosphere at a speed of 2 m/min, and was wound up on a winder for 10 mm without any trouble.
It was possible to fire the entire amount of yarn with a winding thickness of . The obtained carbon fiber has a tensile strength of 2.2 GPa and an elastic modulus of 250 G.
Pa, and the thread diameter was 10.1 μm.

When this yarn was further graphitized at 25° C., the tensile strength was 2.20 Pa, the elastic modulus was 600 G Pa, and the yarn diameter was 9.8 μm.

In this way, carbonized fibers treated at 500°C, 150°C
It has been confirmed that in both cases of carbon fibers treated at 0° C. and graphite fibers treated at 25UO'C, unwinding, winding, doubling, etc. can be easily and freely performed.

Example 2゜Same as Example 1 except that the first carbonization temperature was 650°C.
In the same manner as above, carbon fibers i and charcoal #5 fibers were produced. 6
When the first carbonization was performed at 50° C., no breakage of the yarn on the bobbin was observed. At this time, fIs The tensile strength of the primary carbonized yarn is 0.4 GPa, and the elastic modulus is l 5 GPa
a, (+l+ degree was 2.7%.

The unwinding at this time was slightly more difficult than in Example 1, which was carbonized at 500°C. Furthermore, the tensile strength of the carbon fiber carbonized at 1500C was 2.3 GPa, and the elastic modulus was 250 GPa.

ratio! Carbonized fibers were produced in the same manner as in Example 1, except that a stainless steel bobbin with no air permeability was used.

When the first heat-treated carbonized fiber thus obtained was unwound, the yarn was cut after unwinding to a thickness of approximately 1 mm.

Claims (1)

[Scope of Claims] 1) Optically anisotropic carbonaceous pitch is melt-spun, the spun pitch fibers are doubled and wound onto a breathable bobbin, and the bobbin is infusible under an oxidizing atmosphere. ,690℃
The first heat treatment is carried out in a non-oxidizing atmosphere at a temperature of:
A method for producing carbon fibers and graphite fibers, which comprises performing the following heat treatment. 2) The method for producing carbon fibers and graphite fibers according to claim 1, wherein the second heat treatment is performed while the spun pitch fibers are wound around an air permeable bobbin. 3) The second heat treatment is carried out by unwinding the pitch fibers spun from an air-permeable bobbin and feeding the yarn. Production method. 4) The number of filaments of the pitch fibers before spinning by a melt spinning machine is 50 to 1,000 filaments, and the number of filaments of the pitch fibers after spinning is 200 to 50,000 filaments.
The method for producing carbon fibers and graphite fibers according to any one of claims 1 to 3, characterized in that the fibers are zero filaments. 5) A patent characterized in that the spun pitch fibers having a predetermined number of filaments are obtained by winding the spun pitch fibers around a plurality of bobbins, and then unwinding and doubling the spun pitch fibers. A method for producing carbon fibers and graphite fibers according to claim 4. 6) Pounded pitch fibers having a predetermined number of filaments are obtained by collecting the spun pitch fibers using an air current after convergence, accumulating them in a can shape in an accumulation container, and then unrolling them and doubling them. Claim 4 is characterized in that
The method for producing carbon fibers and graphite fibers as described in 2. 7) A patent claim characterized in that the combined pitch fibers having a predetermined number of filaments are obtained by continuously doubling pitch fibers spun from spinnerets of a plurality of spinning machines while spinning. A method for producing carbon fibers and graphite fibers according to Scope 4. 8) Pounded pitch fibers having a predetermined number of filaments that are subjected to the first heat treatment are obtained by re-unraveling the once-spliced pitch fibers and performing re-splitting. A method for producing carbon fibers and graphite fibers according to claim 4. 9) The method for producing carbon fibers and graphite fibers according to claim 1, wherein the first heat treatment is performed at 400°C to 690°C. 10) The method for producing carbon fibers and graphite fibers according to claim 9, wherein the first heat treatment is performed at 500°C to 550°C. 11) The method for producing carbon fibers and graphite fibers according to claim 1, wherein the temperature increase rate in the first heat treatment is 2 to 10°C/min. 12) The method for producing carbon fibers and graphite fibers according to claim 1, wherein the first heat treatment is performed in an atmosphere of nitrogen gas and/or argon gas. 13) The method for producing carbon fibers and graphite fibers according to claim 12, characterized in that atmospheric gas is circulated and replaced at a rate of 0.05 to 1 time/min. 14) The method for producing carbon fibers and graphite fibers according to claim 1, wherein the first heat treatment is performed under a vacuum of 10^-^1 mmHg or less. 15) Infusibility treatment at a temperature range of 150°C to 400°C,
The method for producing carbon fibers and graphite fibers according to claim 1, wherein the method is carried out in an atmosphere of air, oxygen, or a mixed gas of air and oxygen or nitrogen. 16) The method for producing carbon fibers and graphite fibers according to claim 15, characterized in that atmospheric gas is circulated and replaced at a rate of 0.1 to 5 times/minute. 17) The method for producing carbon fibers and graphite fibers according to claim 15, characterized in that atmospheric gas is blown into the center of the cylindrical bobbin. 18) The method for producing carbon fibers and graphite fibers according to claim 15, wherein the atmosphere is forcibly stirred at a wind speed of 0.1 to 5 m/sec. 19) The method for producing carbon fibers and graphite fibers according to claim 1, wherein the breathable bobbin is a porous cylindrical bobbin with a diameter of 100 to 500 mm. 20) The carbon according to claim 19, which is a metal perforated bobbin or a wire mesh bobbin in which small holes are made throughout the entire surface so that the air permeable bobbin has a porosity of 10 to 75%. Method for producing fibers and graphite fibers. 21) The method for producing carbon fibers and graphite fibers according to claim 19, wherein the material composition of the breathable bobbin is a sintered metal material. 22) The method for producing carbon fibers and graphite fibers according to claim 4, characterized in that the traverse during spinning is 2 to 100 mm/(one revolution of the bobbin). 23) The method for producing carbon fibers and graphite fibers according to claim 4, characterized in that the traverse during doubling is 5 to 100 mm/(one revolution of the bobbin). 24) The pitch fiber winding thickness on the bobbin after doubling is 1 to 1
4. The method for producing carbon fibers and graphite fibers according to claim 4, wherein the carbon fibers and graphite fibers have a diameter of 0.00 mm. 25) The carbon fiber and graphite according to claim 1, wherein the second heat treatment is performed in a temperature range of 1,000 to 3,000°C and in a nitrogen and/or argon atmosphere. Fiber manufacturing method. 26) The optically anisotropic carbonaceous pitch contains about 95% or more of an optically anisotropic phase and has a softening point of about 230 to 320.
The method for producing carbon fibers and graphite fibers according to claim 1, wherein the temperature is .degree.