JPH0390625A - Pitch-based carbon fiber cloth and production thereof - Google Patents

Abstract

PURPOSE:To obtain a pitch-based conjugated fiber cloth giving a thin cloth of pitch-based carbon fiber by the removal of a polymer from a base cloth by melt-spinning a carbonaceous pitch and a thermoplastic organic synthetic polymer compound and forming the resultant pitch-based conjugate fiber in the form of cloth. CONSTITUTION:A pitch-based conjugate fiber cloth having excellent handleability and flexibility is produced in high weaving efficiency by melt-spinning (A) a carbonaceous pitch for the production of carbon fiber (preferably a thermoplastic pitch having a softening point of 230-320 deg.C) and (B) a thermoplastic organic polymer compound having excellent spinnability (preferably polyethylene terephthalate, a copolymerized polyester containing >=60mol% of ethylene terephthalate component or nylon) and forming the produced conjugate fiber in the form of woven fabric, knit fabric, nonwoven fabric, etc., The obtained conjugate fiber cloth can be converted to a pitchbased carbon fiber cloth composed of fine-denier fibers in high efficiency by removing the thermoplastic organic polymer from the cloth and infusibilizing and calcining the product in an oxidizing gas atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. The present invention relates to cloth-like materials such as woven materials, knitted materials, and non-woven materials (herein referred to as "fabrics") made of carbon fibers, and particularly to pitch fibers. A pitch-based composite fiber is used as a precursor, a fabric is formed in advance using the pitch-based composite fiber, and the pitch-based composite fiber fabric is fired to produce a high-performance pitch-based carbon fiber fabric. Features. In this specification, carbon fiber is meant to include graphite fiber.

Such a pitch-based carbon fiber fabric can be suitably used as a carbon fiber cloth as it is, or as a reinforcing fiber cloth when manufacturing cloth prepreg or the like.

Currently, rayon-based and PAN-based carbon fibers as well as pitch-based carbon fibers are widely used in various technical fields.
In particular, pitch-based carbon fibers manufactured from carbonaceous pitches such as petroleum-based pitch and coal-based pitch are
It has attracted attention in recent years because it has a higher carbonization yield and better physical properties such as elastic modulus than N-based carbon fibers, and can be manufactured at low cost. There is.

Currently, pitch-based carbon fibers are produced by: (1) preparing carbonaceous pitch suitable for carbon fiber from petroleum-based pitch, coal-based pitch, etc., heating and melting the carbonaceous pitch, spinning it in a spinning machine, converging it, (2) The pitch fiber bundle is heated to 200 to 350°C in an oxidizing gas atmosphere in an infusible furnace to make it infusible; (3) Subsequently, The infusible fiber bundle is pre-carbonized by heating to 500 to 1500°C under an inert gas atmosphere in a pre-carbonization furnace. (4) Next, the pre-carbonized fiber bundle is heated in a carbonization furnace under an inert gas atmosphere. It is manufactured by heating to 1,500 to 2,000°C to carbonize it, and further heating to 3,000°C to graphitize it.

However, in general, carbonaceous pitch has poor spinnability and the stable spinning range is extremely narrow. Therefore, it is extremely difficult to heat and melt carbonaceous pitch and continuously and stably spin it using a spinning machine. Have difficulty. In particular, in order to obtain carbon fibers with high strength and high elastic modulus, fibers (filaments) of about 5 to 7 μm are used.
In order to produce carbon fibers with a diameter, it is first necessary to spin pitch fibers as a precursor of carbon fibers to a fiber diameter of 10 μm or less, which is practically impossible or extremely difficult.

Furthermore, the pitch fibers before being pre-carbonized are extremely brittle and must be handled with great care. however,
Even if pitch fibers are bundled and doubled with great care, fuzz may occur due to fibers (filaments) being cut during pitch fiber convergence and doubling prior to preliminary carbonization. .

In order to solve the above problems, it has been proposed to prepare carbonaceous pitch with excellent spinnability by processing petroleum-based pitch, coal-based pitch, etc. in various ways to prepare components and remove inorganic foreign matter. It requires various complicated processing steps and has problems in terms of production efficiency and manufacturing cost.

In addition, various proposals have been made for the structure of spinnerets for pitch fibers and the structure of spinning machines for uniform cooling.
Even if a particular carbonaceous pitch is effective, there is no method that can continuously and stably spin various carbonaceous pitches without yarn breakage.

Further, as described above, even if pitch fibers were spun, the difficulty in handling due to the brittleness of the pitch fibers themselves before pre-carbonization was not improved in any way.

On the other hand, compared to unidirectional prepregs, cross prepregs are sometimes used because they are less likely to cause disordered fiber alignment, are easier to handle, and can yield high-strength carbon fiber reinforced plastics.

However, carbon fibers have disadvantages in that they have low elongation, poor flexibility, and are difficult to weave or knit, that is, extremely poor weavability, due to fuzzing caused by abrasion. For this purpose, it has been proposed to weave the yarn before firing treatment such as carbonization or graphitization, but as mentioned above, the yarn before firing is extremely fragile, making it impossible to weave it into a fabric. Met.

The present inventor conducted many research experiments to solve the above problems, and found that by composite spinning carbonaceous pitch with a thermoplastic organic synthetic polymer compound that can be melt-spun and has good spinnability, We have found that the above problems can be solved.

That is, if a pitch-based composite fiber consisting of carbonaceous pitch and a thermoplastic organic synthetic polymer compound that can be melt-spun and has good spinnability is used as a pitch fiber precursor, carbonaceous pitch can be easily cut into threads. It has been found that the yarn can be spun continuously and stably without any problems, has excellent handling properties, and can be easily woven into fabric.

The present invention is based on this new knowledge.

Therefore, an object of the present invention is to prevent fiber alignment from occurring easily;
It is easy to handle, has high elongation, and has excellent flexibility.
To provide a pitch-based composite fiber fabric that can be molded with good weavability and does not cause fuzzing due to abrasion.

Another object of the present invention is that by using the pitch-based composite fiber fabric, various carbonaceous pitches can be continuously and stably spun into yarn without breakage, and that the fabric has excellent handling properties and can be used as desired. It can be easily bundled and doubled according to the conditions, and even small-diameter pitch-based carbon fibers can be produced extremely efficiently.Therefore, it is possible to produce various thin pitch-based carbon fiber fabrics, which have been difficult in the past. It is an object of the present invention to provide a method for producing carbon fiber fabric that can also produce carbon fiber fabric.

The above-mentioned object of thinning is achieved by the pitch-based composite fiber fabric and the method for producing carbon fiber according to the present invention. In summary, the present invention:
A pitch-based conjugate fiber formed from component A consisting of carbonaceous pitch for producing carbon fibers and component B consisting of a thermoplastic organic synthetic polymer compound with good spinnability is spun, and if necessary, it is bundled. , the pitch-based composite fiber bundle obtained by doubling,
It is a pitch-based composite fiber fabric formed by molding, that is, weaving, a fabric such as a woven fabric, a knitted fabric, or a nonwoven fabric.

In other words, the feature of the present invention is that when producing a pitch-based carbon fiber fabric, a pitch-based conjugate fiber is spun as a pitch fiber precursor, and the pitch-based conjugate fiber is woven to form a fabric. .

Referring to FIG. 1, one embodiment of the pitch-based composite fiber for manufacturing carbon fibers used in the present invention is shown. In this example, the pitch-based composite fiber 1A includes an A component 2 made of carbonaceous pitch for carbon fiber production, and a thermoplastic organic synthetic polymer with good spinnability formed around the A component 2. It is composed of component B 4 consisting of a compound.

FIG. 4 schematically shows an embodiment of a spinneret for producing such a pitch-based composite fiber 1A for producing carbon fibers. In this embodiment, the spinneret 100 has first, second, and 30th gold plates 102, 104, and 106, and the 10th gold plate 102 and the 20th gold plate 104 are disposed in close contact with each other. The gold plate 106 is the second
0 gold plate 104 at a predetermined distance,
As will be explained later, a supply passage 108 for the B component material is formed.

Further, the first spinneret plate 102 is formed with a supply hole 110 for the material for component A, and the second spinneret plate 104 is formed with a supply hole 110 for the material for component A.
A hollow spinning nozzle 112 is connected to the A component material supply hole 1.
It is installed in alignment with 10. The spinning nozzle 112 is
The B component material supply passage 108 and the 30th gold plate 1
06 and further extends through the third spinneret play)-1
An annular nozzle 114 for the B component material from the material supply passage 108 is formed around the spinning nozzle 112 at 06.

In the spinneret 100 having the above configuration, the material supply hole 110
When the material for the A component, that is, carbonaceous pitch is supplied to the spinning nozzle 112, and the material for the B component, that is, the thermoplastic organic synthetic polymer compound, is supplied to the annular nozzle 114 from the material supply passage 108. As shown in FIG. 1, the carbonaceous pitch for producing carbon fiber used in the present invention is A component 2, and a thermoplastic organic synthetic polymer with good spinnability is placed around the A component 2. B component 4 formed from a molecular compound
A pitch-based composite fiber LA for producing carbon fibers having the following properties is spun.

FIGS. 2 and 3 show other examples of pitch-based composite fibers for producing carbon fibers.

FIG. 2 shows a so-called multifilamentary pitch-based conjugate fiber 1B for producing carbon fibers, in which a large number of A components 2, usually 6 to 100, are dispersed in a B component 4 in a roughly-shaped manner.

FIG. 5 shows an embodiment of a spinneret 100A for producing such a pitch-based composite fiber IB for producing multifilamentary carbon fibers. The spinneret 100A according to this embodiment has the same structure as the spinneret described in FIG. A fourth spindle plate 116 is provided in close contact with the spinneret plate 116, and a funnel-shaped collecting nozzle portion 118 for collecting the composite fibers spun from the spinning nozzle is formed on the spinneret plate 116. They are different.

Figure 3 shows a pitch-based composite fiber 1C for producing carbon fibers in which component A 2 is arranged in a fan shape within a fiber with a circular cross section, and the component A 2 is surrounded by a component 4 around the fiber, so that the whole has a circular cross section.
shows.

In each of the above embodiments, the pitch-based composite fiber 1 has an A component 2 consisting of carbonaceous pitch for carbon fiber production, and a B component 4 consisting of a thermoplastic organic synthetic polymer compound with good spinnability.
However, the pitch-based composite fiber used in the present invention is not limited to this;
A so-called split pitch-based composite fiber 1° in which the A component 2 is divided by the B component 4 and a part of the A component 2 is exposed on the yarn surface as shown in FIGS. (1°A
~1°D).

Referring to FIG. 6, pitch-based splittable conjugate fiber 1°A for carbon fiber production includes an A component 2 made of carbonaceous pitch for carbon fiber production, and is arranged in such a manner that the A component 2 is divided. It is composed of component B 4, which is a thermoplastic organic synthetic polymer compound with good spinnability. At this time, according to this embodiment, the entire outer periphery of component A is not covered with component B, but a portion is exposed to the outside, that is, to the thread surface.

7 to 9 show other examples of pitch-based splittable composite fibers 1° for producing carbon fibers.

In the embodiment of FIGS. 7 and 8, the radially arranged B
Component 4 provides composite fibers 1'B and 1'C in which component A 2 is divided into four or eight parts.

Further, in the embodiment shown in FIG. 9, a composite fiber 1'D is provided in which the thread has an oval cross section and the A component 2 is divided into four by the B component 4 arranged in parallel. In any of the examples, a part of the A component 2 is exposed on the yarn surface.

FIGS. 10 to 13 show pitch-based splittable conjugate fibers 1'C for producing carbon fibers shown in FIG. 8 for producing such splittable pitch-based conjugate fibers for producing carbon fibers.
An embodiment of a spinneret that can suitably spin a spinneret is shown schematically.

In this embodiment, the spinneret 200 has first and twentieth gold plates 201 and 202 that are closely attached to each other,
The 20th gold plate 202 has an opening 203 opened at the mating surface of the first and 20th gold plates 201 and 202, and a spinning hole 204 communicating with the opening 203. In addition, the 20th gold plate 202 is marked with X- in FIG.
As shown in FIG. 12, which is a view taken in the direction X, in this embodiment, eight communication grooves 205 are formed in the radial direction in a manner that communicates with the opening 203.

On the other hand, an A component supply passage 206 is formed in the tenth gold plate 201 at a position corresponding to the opening 203 of the first base plate, and at the bottom of the supply passage 206 there is a
As shown in FIG. 11, which is a view taken along Y-Y, four communication holes 207 communicating with the spinning hole opening 203 are formed at equal intervals in the center and eight in the outer circumference. . Moreover, as understood from FIG. 11, the 10th gold plate 201
, eight communication grooves 208 are formed that do not intersect with the communication holes 207 and correspond to the communication grooves 205 . Some grooves in the communication groove 208 are connected to the spinning hole opening 20.
In this embodiment, it is formed by connecting four grooves 208 in an X-shape. Each communication groove 208 communicates with a B component supply passage 209 formed in the tenth gold plate 201 .

In the spinneret 200 having the above configuration, the material supply hole 206
It is understood from FIG. 13 that the material for the Afi component, that is, the carbonaceous pitch, and the material for the B component, that is, the thermoplastic organic synthetic polymer compound, are supplied from the material supply passage 209. As shown in FIG. 8, component A 2 consisting of carbonaceous pitch for carbon fiber production is replaced with component B made of a thermoplastic organic synthetic polymer compound with good spinnability.
Pitch-based splittable composite fiber 1'C for producing carbon fibers split in component 4 is spun.

In the above-mentioned pitch-based composite fiber for manufacturing carbon fibers which can have various forms, the ratio of A component 2 to the yarn cross-sectional area is 50 to 9.
Therefore, the B component 4 is set to be 50 to 5%.

If the B component 4 is less than 5%, the effect of the B component formed from a thermoplastic organic synthetic polymer compound with good spinnability cannot be sufficiently exhibited, and both spinnability and composite properties deteriorate. On the other hand, even if B component 4 exceeds 50%, as will be explained later,
Although the spinnability and composite properties are good, component B 4 is not a component that contributes to the physical properties of the carbon fiber as a product and is removed prior to firing, so it should be minimized for economic reasons. Therefore, it is considered undesirable if the B component exceeds 50%.

In addition, in the case of the split type pitch-based composite fiber 1° (1°A to 1°D) shown in Figures 6 to 9, the ratio of A component 2 to the yarn cross-sectional area is 50 to 90. %, therefore, it is more preferable for component B 4 to be 50 to 10%.

As component B 4, a thermoplastic organic synthetic polymer compound is used, and in particular, polyethylene terephthalate, a copolyester containing at least 60 mol% of ethylene terephthalate, or nylon such as nylon 6 and nylon 66 are preferably used. Ru.

In addition, as component A 2, any carbonaceous pitch conventionally used for manufacturing carbon fibers, that is, petroleum-based pitch,
Thermoplastic pitches such as coal-based pitches may be used, but
If the softening point of the carbonaceous pitch used exceeds 3 to 20°C, thermal decomposition of the thermoplastic organic synthetic polymer used as component B 4 will become intense, causing spinning defects, which is not preferable. In addition, the softening point of carbonaceous pitch is 23
If it is lower than 0°C and lowers to about 210°C, the melt viscosity balance with component B 4 will be poor and the components A will coalesce, resulting in poor composite properties, which is not preferable.

The pitch-based conjugate fiber for producing carbon fibers produced as described above is bundled and doubled as necessary to form a pitch-based conjugate fiber bundle having a predetermined number of filaments.

According to the present invention, the pitch-based composite fiber bundle is then:
If desired, it is formed into fabrics such as various forms of woven or knitted fabrics, and even non-woven fabrics.

According to the results of research experiments conducted by the present inventors, the pitch-based composite fibers formed according to the present invention have a tensile strength of 1.2 to 5 times that of conventional pitch fibers, and an elastic modulus of It has only about 1/100th the carbon fiber content of later carbon fibers, has significantly improved handling properties, and has extremely good flexibility, making it possible to manufacture a wide variety of textiles using normal weaving techniques. I found out something.

The B component contained in the pitch-based composite fiber fabric is then removed to form a pitch fiber fabric consisting only of the carbonaceous pitch component, that is, the A component. Possible methods for removing component B include solvent removal.

When following the solvent removal method, if the Bfi component is polyethylene terephthalate or a copolyester containing at least 60 mol% of ethylene terephthalate, the solvent may be an alkaline aqueous solution, such as caustic soda at 95°C, IN. solution is used, and B
Sulfuric acid or formic acid is preferably used when the component is formed of nylon.

The pitch fiber fabric from which the B component has been removed in this way is
According to the usual pitch-based carbon fiber manufacturing method as described above, that is, (a) heating the pitch fiber fabric to 200 to 350 ° C. in an oxidizing gas atmosphere in an infusible furnace to make it infusible; (b) Subsequently, the infusible fabric is pre-carbonized by heating to 500 to 1500°C in an inert gas atmosphere in a pre-carbonization furnace; (c) Next, the pre-carbonized fabric is heated in a carbonization furnace to A carbon fiber fabric is produced by heating to 1500 to 2000°C in an inert gas atmosphere to carbonize, and further heating to 3000°C to graphitize.

According to the present invention, it is possible to continuously and stably spin yarn using various carbonaceous pitches without yarn breakage, and moreover,
Carbon fibers (filaments) with a small diameter of ~7 μm can be easily produced, and therefore thin fabrics can be produced.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A carbonaceous pitch containing approximately 55% optically anisotropic phase and having a softening point of 232° C. was used as a precursor pitch. Using a cylindrical centrifugal separator with an effective volume of 200 m2, this precursor pitch was continuously separated into a pitch with a large amount of optically anisotropic phase and a pitch with a large amount of optically isotropic phase at a temperature of 370°C and a centrifugal force of 30,000 G. It was separated into two parts and each was extracted.

The obtained pitch containing a large amount of optically anisotropic phase contained 98% of the optically anisotropic phase, had a softening point of 265° C., and had a quinoline solubility of 29.5%. This carbonaceous pitch was used as the material for the A component. As the material for component B, polyethylene terephthalate having an intrinsic viscosity of 0.65 in an orthochlorophenol solution at 25° C. was used.

The structure is as shown in FIG. 5, the number of A component nozzles per filament is 36, the discharge hole diameter is 1.0 mm,
A spinneret with 30 discharge holes was used, the temperature of the spinneret was maintained at 310°C, and the winding speed was 1000.
Spinning was carried out for 60 minutes at m/min. Stable spinning was carried out continuously without any yarn breakage during spinning.

An oil in water type polyester filament textile oil containing a smoothing agent, an antistatic agent, and an emulsifier was applied to the spun pitch-based composite fiber bundle (yarn) by roller contact. The adhesion amount was 0.7% by weight based on the yarn.

The diameter of each single filament obtained was approximately 41 μm, the number of A components was 36, and the diameter of each A component was approximately 6 μm, with no merging of A components and a completely independent and uniform form. , and showed a good composite state. The ratio of component A/component B was 80/20 in terms of the cross-sectional area of the yarn. In addition, the pitch-based composite fiber bundle had no fuzz and had excellent handling properties.

Next, the pitch-based composite fiber bundle was given 15 actual twists per meter and a sizing agent was added thereto, and then woven into a plain weave with a weaving width of 60 mm using a tape loom. The weavability was good, and there was almost no yarn breakage or fuzz.

Next, the narrow woven fabric made of the pitch-based composite fiber bundle thus obtained was placed in a caustic soda aqueous solution for 20 minutes under a tension of 240 g.

The caustic soda aqueous solution had a caustic soda concentration of 40 g/β and a bath temperature of 95°C. As a result, the B component of the yarn in the fabric was dissolved and removed, and a pitch fiber fabric consisting only of the A component, which is substantially carbonaceous pitch, was obtained.

The pitch fiber fabric was passed through a hot water bath at 95°C to wash and remove the hydrolyzate of caustic soda and polyethylene terephthalate adhering to the threads.

Subsequently, this pitch fiber fabric was heated to a furnace entrance temperature of 180°C.
The fibers were continuously introduced into a continuous infusibility furnace in an oxygen-rich gas atmosphere (oxygen/nitrogen = 40/60) with a maximum temperature of 280°C at a threading speed of 1 m/min. 4 for temperatures from 180℃ to 280℃
The temperature was raised at a rate of 0.degree. C./min and held at 280.degree. C. for 5 minutes to make it infusible.

The infusible fabric was continuously passed through a continuous carbonization furnace having a nitrogen gas atmosphere with a furnace entrance temperature of 300° C. and a maximum temperature of 1500° C. at a threading speed of 1 m/min for carbonization. Further, the carbonized fabric was placed in a continuous graphitization furnace having an argon gas atmosphere, and graphitized at 2500° C. for 15 minutes.

The carbon fiber fabric thus obtained had almost no fuzz, had a thickness of 0.15 mm, and had extremely excellent properties.

Example 2 As component B, instead of polyethylene terephthalate, 2.5 mol% of 5 was used as a copolymer component based on the total acid component.
-Executed except that an ethylene terephthalate-based copolyester containing a sodium sulfoisophthalic acid component and the remaining acid component consisting of terephthalic acid (intrinsic viscosity at 25°C, intrinsic viscosity in orthochlorophenol solution: 0.62) was used. A pitch-based composite fiber bundle was obtained by spinning using the same materials and under the same conditions as in the example.

Continuous and stable spinning was performed without any yarn breakage during spinning.

Using the obtained pitch-based conjugate fiber bundle, a pitch-based conjugate fiber fabric was produced in the same manner as in Example 1, and a carbon fiber fabric was also produced in the same manner as in Example 1.

The carbon fiber fabric obtained in this way had almost no fuzz, had a thickness of 0.21 mm, and had extremely excellent properties.

Example 3 A carbonaceous pitch containing approximately 55% optically anisotropic phase and having a softening point of 232° C. was used as a precursor pitch. This precursor pitch was collected using a 42 cylindrical centrifugal separator with an effective volume of 200 m at a temperature of 370°C and a centrifugal force of 3000 m.
As 0G, pitches containing many optically anisotropic phases and pitches containing many optically isotropic phases were continuously separated and extracted.

The obtained pitch containing a large amount of optically anisotropic phase contained 98% of the optically anisotropic phase, had a softening point of 265° C., and had a quinoline solubility of 29.5%. This carbonaceous pitch was used as the material for the A component. As the material for component B, polyethylene terephthalate having an intrinsic viscosity of 0.65 in an orthochlorophenol solution at 25° C. was used.

A split spinneret with a structure as shown in Figures 10 to 13, with a discharge hole diameter of 0.30 mm and a number of discharge holes of 24, is used, and the temperature of the spinneret portion is maintained at 310°C. Then, spinning was carried out for 60 minutes at a winding speed of 800 m/min. Stable spinning was carried out continuously without any yarn breakage during spinning.

The diameter of each single yarn (filament) obtained was about 19 μm, the number of A components was 8, and the fineness of each A component was about 0.36 denier, and the A components did not join together and were completely independent. It had a uniform morphology and showed a good composite state. Further, the ratio of component A/component B was 80/20 in terms of the cross-sectional area of the yarn. Furthermore, the obtained pitch-based composite fiber bundle was free of fuzz and had excellent handling properties.

Ten of the pitch-based conjugate fiber bundles were spliced, and a pitch-based conjugate fiber fabric was produced in the same manner as in Example 1. That is, the actual twist is 15 per meter in a pitch-based composite 1ti 41℃ bundle.
After applying a sizing agent, the fabric was woven by hand using a tape loom with a weaving width of 60 mm. The weavability was good, and there was almost no yarn breakage or fuzz.

Next, the narrow woven fabric made of the pitch-based composite fiber bundle thus obtained was passed through a 1N aqueous sodium hydroxide solution at 95°C at a speed of 1 m/min under a predetermined tension. As a result, the B component of the yarn was dissolved and removed, and a pitch fiber fabric consisting only of the A component, which is substantially carbonaceous pitch, was obtained.

Subsequently, this pitch fiber fabric was heated to a furnace entrance temperature of 180°C.
℃, and was continuously introduced at a speed of 1 m/min into a continuous infusibility furnace in an oxygen-rich gas atmosphere (oxygen/nitrogen = 40/60) with a maximum temperature of 280°C. 4°C from 180°C to 280°C
The temperature was raised at 280° C./min for 5 minutes to make it infusible.

The infusible fabric was continuously passed through a continuous carbonization furnace having a nitrogen gas atmosphere with a furnace entrance temperature of 300° C. and a maximum temperature of 1500° C. at a speed of 1 m/min for carbonization. Further, the carbonized fabric was placed in a continuous graphitization furnace having an argon gas atmosphere, and graphitized at 2500° C. for 15 minutes.

The carbon fiber fabric obtained in this way had almost no fuzz, had a thickness of 0.24 mm, and had extremely excellent properties.

Example 5 Spinning was carried out using the same materials and under the same conditions as in Example 1, except that the optical anisotropy fraction and softening point of carbonaceous pitch were variously changed as the material for Aff1. The results are shown in Table 1.

If the softening point of the carbonaceous pitch used exceeds 320°C, thermal decomposition of the thermoplastic organic synthetic polymer used as component B will become intense, causing poor spinning, which is undesirable. The softening point of is 230℃
It can be seen that when the temperature decreases to about 210° C., the melt viscosity balance with the B component becomes poor and the A components coalesce, resulting in poor composite properties, which is not preferable.

Next, the pitch-based composite fiber bundle was given 15 actual twists per meter and a sizing agent was added thereto, and then woven into a plain weave with a weaving width of 60 mm using a tape loom.

Next, the narrow woven fabric made of the pitch-based composite fiber bundle thus obtained was run in a caustic soda aqueous solution for 20 minutes under a tension of 240 g.

The caustic soda aqueous solution had a caustic soda concentration of 40 g/°C and a bath temperature of 95°C. As a result, the B component of the yarn in the fabric was dissolved and removed, and a pitch fiber fabric consisting only of the Ad component, which is essentially carbonaceous pitch, was obtained.

The pitch fiber fabric was passed through a hot water bath at 95°C to wash and remove the hydrolyzate of caustic soda and polyethylene terephthalate adhering to the threads.

Subsequently, this pitch fiber fabric was heated to a furnace entrance temperature of 180°C.
℃, and was continuously introduced at a speed of 1 m/min into a continuous infusibility furnace in an oxygen-rich gas atmosphere (oxygen/nitrogen = 40/60) with a maximum temperature of 280°C. 4℃/from temperature 180℃ to 280℃
The mixture was heated to 280° C. for 5 minutes to make it infusible.

The infusible fabric was continuously passed through a continuous carbonization furnace having a nitrogen gas atmosphere with a furnace entrance temperature of 300° C. and a maximum temperature of 1500° C. at a speed of 1 m/min for carbonization. Further, the carbonized fabric was placed in a continuous graphitization furnace having an argon gas atmosphere, and graphitized at 2500° C. for 15 minutes.

The appearance of the carbon fiber fabric thus obtained was as shown in Table 1.

Table 1 Example 6 Carbonaceous pitch containing about 55% optically anisotropic phase and having a softening point of 232° C. was used as the precursor pitch. This precursor pitch was heated at a temperature of 370°C and a centrifugal force of 30,000 using a cylindrical centrifugal separator with an effective volume of 200rr + j2.
As G, pitches with many optically anisotropic phases and pitches with many optically isotropic phases were continuously separated and extracted.

The obtained pitch containing a large amount of optically anisotropic phase contained 98% of the optically anisotropic phase, had a softening point of 265° C., and had a quinoline solubility of 29.5%. This carbonaceous pitch was used as a material for AF&. For the material of component B, 25℃,
Intrinsic viscosity in orthochlorophenol solution is 0.6
No. 5 polyethylene terephthalate was used.

The structure is as shown in Fig. 5, the number of A component nozzles per filament is 36, and the discharge hole diameter is 1.0 mm.
Discharge spinning was carried out using a spinneret having 30 discharge holes and maintaining the temperature of the spinneret at 320'C. The discharged yarn runs through a thinning zone in which the atmosphere is controlled, during which it is sucked and thinned using an air sucker, and the air is then blown to a width of about 300 mm while being opened using a type of fiber opening device.
A web was produced by adjusting the conveyor speed of the web forming machine so that the average basis weight was 120 g/m''.

The diameter of each filament forming the web is approximately 20
ILm, the number of A components was 36, the diameter of each A component was about 6 μm, there was no merging of A components, a completely independent uniform morphology, and a good composite state. A component/
The ratio of component B was 80/20 in terms of the cross-sectional area of the yarn.

In addition, there was little yarn breakage or fluffing during the spinning, opening, and web forming processes, and the web was good.

Next, the web was cut into lengths of 500 mm and treated with a caustic soda aqueous solution with a caustic soda concentration of 40 g/β and a bath temperature of 95° C. for 30 minutes to dissolve and remove component B to obtain a pitch fiber web consisting only of component A, which is carbonaceous pitch. Ta.

The pitch fiber web was passed through a hot water bath at 95°C to wash off adhering caustic soda.

Subsequently, this pitch fiber web was heated to an initial temperature of 180°C.
The mixture was placed in an infusibility furnace in an oxygen-rich gas atmosphere (oxygen/nitrogen = 40/60), heated to 280'C at a rate of 4°C/min, and held at 280°C for 5 minutes to be infusible.

The infusible web was placed in a carbonization furnace in a nitrogen gas atmosphere with an initial temperature of 300'C and heated at 30°C until a maximum temperature of 1500°C.
The temperature was raised at a rate of 1/min to carry out carbonization. Further, the carbonized web was placed in a graphitization furnace having an argon gas atmosphere, and heated at 2500
Graphitization was carried out at ℃ for 20 minutes.

The carbon fiber web thus obtained had no fuzz and had an excellent appearance.

As described above, according to the present invention, fiber arrangement holes are difficult to occur, the handleability is excellent, the elongation is large, the flexibility is excellent, and the occurrence of fuzzing due to abrasion is avoided. We can provide a pitch-based composite fiber fabric with extremely good weavability without any
Therefore, by using such a pitch-based conjugate fiber fabric, it is possible to produce various kinds of thin pitch-based carbon fiber fabrics, which have been considered difficult in the past.

[Brief explanation of drawings]

1 to 3 are cross-sectional views of examples of pitch-based composite fibers for producing carbon fibers. FIGS. 4 and 5 are cross-sectional views showing the structure of a spinneret for producing pitch-based composite fibers for producing carbon fibers. 6 to 9 are cross-sectional views of other examples of pitch-based composite fibers for producing carbon fibers. FIG. 10 is a sectional view showing the structure of a spinneret according to another embodiment for producing pitch-based composite fibers for producing carbon fibers. FIG. 11 is a plan view taken along line XX in FIG. 10. FIG. 12 is a plan view taken along line Y--Y in FIG. 10. FIG. 13 is a diagram illustrating how each material is connected in the spinneret of FIG. 10. 1, l゛: Pitch-based composite fiber for carbon fiber production 2: A component 4: B component

Claims (1)

[Claims] 1) Component A consisting of carbonaceous pitch for producing carbon fibers and B consisting of a thermoplastic organic synthetic polymer compound with good spinnability.
By spinning the pitch-based conjugate fibers formed from the components, and forming the resulting pitch-based conjugate fiber bundles by bundling and doubling as necessary into fabrics such as woven fabrics, knitted fabrics, and non-woven fabrics. The formed pitch-based composite fiber fabric. 2) The pitch-based composite carbon fabric according to claim 1, wherein the ratio of the A component to the yarn cross-sectional area of the pitch-based composite fiber is 50 to 95%, and the B component is 50 to 5%. 3) The carbonaceous pitch for producing carbon fibers forming component A is a thermoplastic pitch with a softening point of 230°C to 320°C;
The thermoplastic organic synthetic polymer compound forming the component is polyethylene terephthalate, a copolyester containing at least 60 mol% of ethylene terephthalate component,
or nylon, the pitch-based composite carbon fabric according to claim 1. 4) Component A consisting of carbonaceous pitch for carbon fiber production and B consisting of a thermoplastic organic synthetic polymer compound with good spinnability.
A step of spinning pitch-based composite fibers formed from the components and, if necessary, bundling and doubling to produce a pitch-based composite fiber bundle; A step of removing the B component from the pitch-based composite fiber fabric to produce a pitch fiber fabric made of pitch fibers consisting of the A component, and exposing the pitch fiber fabric to an oxidizing gas atmosphere. The process of making it infusible by
and a method for producing a pitch-based carbon fiber fabric, comprising the step of firing the infusible fabric. 5) The method for producing a pitch-based carbon fiber according to claim 4, wherein the ratio of the A component to the yarn cross-sectional area of the pitch-based composite fiber is 50 to 95%, and the B component is 50 to 5%. 6) The carbonaceous pitch for producing carbon fibers forming component A is a thermoplastic pitch with a softening point of 230°C to 320°C;
5. The method for producing a pitch-based carbon fiber fabric according to claim 4, wherein the thermoplastic organic synthetic polymer compound forming the component is polyethylene terephthalate or a copolyester containing at least 60 mol% of ethylene terephthalate. 7) The method for producing pitch-based carbon fibers according to claim 6, wherein component B is removed using an alkaline aqueous solution.