JPH04163319A - Pitch-based carbon fiber having extremely high thermal conductivity and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title yarn having high thermal conductivity and compression strength without damaging tensile strength and modulus in tension by infusibilizing pitch fiber, drawing and heat-treating in an oxygen-containing atmosphere, drawing and preliminarily carbonizing and carbonizing in an inert gas atmosphere while drawing. CONSTITUTION:Pitch fiber obtained by spinning carbonaceous pitch is infusibilized, the infusibilized fiber is passed through an oxygen-containing atmosphere at 300-500 deg.C for 1-200 seconds and drawn by 5-100% and heat- treated. successively, the heat-treated fiber is passed through an oxygen containing atmosphere having 500-700 deg.C maximum temperature for 20-300 seconds, drawn by 5-100%, preliminarily carbonized and then carbonized in an inert gas atmosphere having 2,600-3,200 deg.C maximum temperature while being drawn by 1-30% to give the objective fiber having 500-1,500 w/m/k/ thermal conductivity in the direction of fiber axis, lamination thickness of fiber crystal structure (Lc002)/density (rho) of 120-500, 0-30% melt binding degree and 0.2-0.4 GPa compression strength.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention generally relates to carbon fibers, and in particular, carbon fibers have high thermal conductivity, high compressive strength, and excellent yarn handling properties. The present invention relates to ultra-high thermal conductivity pitch-based carbon fibers that can be widely used as carbon fiber-reinforced composite materials for equipment printed circuit boards, IC boards, heat sinks, etc., and a method for producing the same.

BACKGROUND OF THE INVENTION In recent years, various fiber-reinforced composite materials have been proposed as materials for printed circuit boards, IC boards, and heat sinks of electronic devices, for example. It is essential that the fibers used in such fiber-reinforced composite materials have particularly high thermal conductivity.

Conventionally, PAN-based and pitch-based carbon fibers have been widely produced and used as carbon fibers, but PAN-based carbon fibers have high mechanical properties but extremely low thermal conductivity, and are usually 10%
W'/m/K or less, 75 W/m
/ Nothing higher than K is known. Furthermore, it is inappropriate to use PAN-based carbon fibers in the above-mentioned fiber-reinforced composite materials, which can also be expected to improve thermal conductivity.

On the other hand, although pitch-based carbon fibers have high thermal conductivity, there are no known pitch-based carbon fibers that have well-balanced and sufficiently high mechanical properties, particularly compressive strength and yarn handling properties when producing fiber-reinforced composite materials.

The problem that Kazuaki is trying to solve Carbon fibers used in carbon fiber-reinforced composite materials for printed circuit boards, etc., are required to have high thermal conductivity as well as increased mechanical properties, especially compressive strength. .

Furthermore, for example, when manufacturing a carbon fiber reinforced composite material for a heat conduction part or heat sink of a printed circuit board, the carbon fiber bundle may be impregnated with a metal material. In order to increase the impregnability of metal materials,
It is required that the carbon fiber bundle has little melting and sticking, that is, good yarn handling properties.

In the process of researching the relationship between the crystal structure of pitch-based carbon fibers, thermal conductivity, and mechanical strength, the present inventors investigated the crystal structure of carbon fibers, particularly the lamination thickness (L c
002) within a specific range, more specifically, by setting the laminated thickness (L c 002)'/density (ρ) within a specific range, the tensile strength and tensile modulus of elasticity above a predetermined level can be achieved. In addition, it is possible to obtain pitch-based carbon fibers with excellent ultra-high thermal conductivity and dramatically increased thermal conductivity and compressive strength. It has been found that by doing so, it is possible to produce a carbon fiber-reinforced composite material that has excellent thread handling properties when producing a composite material.

The present invention has been made based on this new knowledge.

Therefore, the object of the present invention is to provide an ultra-high thermal conductivity pitch-based carbon fiber that has extremely high thermal conductivity and high compressive strength without impairing tensile strength and tensile modulus, and has excellent yarn handling properties. The purpose of the present invention is to provide a method for producing the same.

111 Kasa Fireworks A Taishu Sub” 1 The above object is achieved by the ultra-high thermal conductivity pitch-based carbon fiber according to the present invention. In summary, the present invention provides fiber axial thermal conductivity of 500 to 1500 W/m/K,
Lamination thickness (L c 002)/density (ρ) is 120 to 5
00, fusion adhesion 0-30%, and compressive strength 0.2
It is a pitch-based carbon fiber with an ultra-high thermal conductivity of ~0.40 Pa.

As mentioned above, in the process of research and development to obtain pitch-based carbon fibers with good thermal conductivity using pitch as a raw material, the present inventors first attempted to increase the thermal conductivity along the fiber axis direction. Is it necessary to promote crystallization of the fibers?
It has been found that when crystallization progresses too much, the mechanical properties of the fibers, particularly the compressive strength, are significantly reduced.

In other words, the present inventors have developed an ultrahigh thermal conductivity of 500 W/m/K or more, that is, 500 to 1500 W/m/K, and a compressive strength of 0.2 to 0.4 G.
Pa, and has a tensile strength of 2.5 to 4.5 GPa,
In order to obtain a pitch-based carbon fiber with ultra-high thermal conductivity and balanced mechanical properties with a tensile modulus of 700 to 95oGPa, it is necessary to carefully examine the crystal structure of the carbon fiber, especially the lamination thickness (
L C002) must be within a specific range, that is, more specifically, the value of laminated thickness (L C002)/density (ρ) must be within a range of 120 or more and 500 or less. I discovered that this is not the case. If the value of lamination thickness (La2O2)/density (ρ) is less than 120, the thermal conductivity will not reach 500W/m/K, and
If this value exceeds 500, the compressive strength is 0°2G.
Pa, and mechanical properties that are well balanced with tensile strength and tensile modulus cannot be obtained.

To explain further, in the high thermal conductivity pitch-based carbon fiber according to the present invention, among the factors that determine the crystal structure as described above, the lamination thickness (L c 002)
Is the lamination thickness (L c 0
02) (260th to 1000th person, and the crystal length (
La1. lO) is 300 to 1000 people, and the interlayer spacing (
d oo2) is estimated to be 3.36 to 3.39 people. Furthermore,
The density (ρ) of the fibers of the present invention is generally between 218 and 2.24.
g/cm".

Furthermore, by setting the degree of fusion and agglutination to 30% or less, the pitch-based carbon fiber according to the present invention increases the yarn handling property when manufacturing composite materials, and makes it possible to produce good carbon fiber reinforced composite materials. Can be manufactured. If the fusion degree exceeds 30%,
For example, when manufacturing carbon fiber δ1# reinforced composite material by impregnating carbon fibers with metal such as aluminum into 11 bundles, the yarn handling property is usually 100 to 1. OOO
The molten metal is not uniformly impregnated into the carbon fiber bundle made of O filaments, making it impossible to produce a carbon fiber reinforced composite material with desired properties.

The ultra-high thermal conductivity pitch-based carbon fiber according to the present invention is obtained by infusible pitch fiber obtained by spinning carbonaceous pitch in the usual manner, and the infusible infusible synthetic fiber Afl: 300 to 50.
0''C1 is preferably subjected to a 5-100% stretching heat treatment in an oxygen-containing atmosphere at 350-480°C for a very short time, followed by a maximum temperature of 500-700°C5, preferably 550-650'C. 5 to 100% stretching preliminary carbonization treatment in an oxygen-containing atmosphere of
It has been found that it can be suitably produced by performing carbonization while performing a stretching treatment of ~30%.

According to the production method of the present invention, brittle infusible fibers that have been made infusible by heating to 150 to 350°C in an oxidizing atmosphere are heated to 300 to 500°C before being pre-carbonized. Since the treatment is carried out for a short time in a containing atmosphere, the surface of the yarn is selectively oxidized, while the interior of the yarn undergoes thermal polymerization and carbonization due to high temperature heat. As a result, the infusible fibers become stronger, and the infusible fibers can be further stretched in the pre-carbonization furnace, which is thought to reduce the degree of fusion and agglutination of the pre-carbonized fibers.

Furthermore, by performing the stretching heat treatment in three stages: after the infusibility treatment, the pre-carbonization treatment, and the carbonization treatment, the orientation of the fibers is improved, and in particular, the thermal conductivity is significantly improved. It has been found that yarns with increased strength and ultra-high thermal conductivity can be obtained. The ultra-high thermal conductivity pitch-based carbon fiber of the present invention (the above-mentioned structure) cannot be obtained by -stage or two-stage stretching heat treatment.

In addition, the oxygen degree in the oxygen-containing atmosphere during the first stage stretching heat treatment after the infusibility treatment is 5 to 80%, and the residence time in the furnace is 1 to 200 seconds (preferably 10 to 100 seconds).
Tension per filament is 0.003~0.1.7g
It is preferable that the acid concentration in the oxygen-containing atmosphere during the second stage stretching heat treatment during the preliminary carbonization treatment is 001 to 30.
%, the residence time in the furnace is 20 to 300 seconds (preferably 50 to 200 seconds), and the tension per filament is 0.0
06-0.33g is suitable. Furthermore, the residence time in the furnace during the third stage stretching heat treatment during carbonization is 1 to 100.
min (preferably 2-6° min), ] Tension L per filament! :0.05-20g is suitable.

Next, the method for producing the ultra-high thermal conductivity pitch-based carbon fiber according to the present invention will be explained in more detail.

First, carbonaceous pitch can be spun by methods well known to those skilled in the art. For example, 1 to 2,000 carbon pitches suitable for manufacturing carbon fiber, such as petroleum-based pitch, coal-based pitch, and pitch made from aromatic hydrocarbons, are heated and melted.
Preferably, 50 to 1000 filaments are spun,
A sizing agent is applied to each filament using a commonly used oiling roller, and the large number of filaments are bundled and wound around a bobbin as a single thread.

As a sizing agent, i! For example, water, ethyl alcohol, isopropyl alcohol, n-propyl alcohol,
Alcohols such as butyl alcohol or viscosity 5 to 1
000 cst (25°C) dimedylbolysiloxane,
Alkylphenylbolysiloxenes etc. diluted with low boiling point silicone oil (polysiloxane) or paraffin oil or other solvents, or dispersed in water with an emulsifier added, as well as graphite, polyethylene glycol and hindered esters. Dispersed ones: Surfactants diluted with water: Other usual fibers, such as those that do not harm pitch fibers among the various oils used for polyester fibers, can be used.

The amount of the sizing agent applied to the pitch fibers is usually 0.01 to 10% by weight, particularly preferably 0.05 to 5% by weight.

The yarn consisting of a large number of filaments once wound onto bobbins as described above can be unwound by simultaneously unwinding a plurality of bobbins, for example, 2 to 50 bobbins, or by dividing it into multiple times, for example, the first time. By repeatedly unwinding and doubling 2 to 10 yarns, then the remaining yarn,
2 to 50 yarns are bundled (paired) and 100 to 1000
00 filaments, preferably 500-10000 filaments to form a pitch fiber bundle (hereinafter simply referred to as "pitch fibers").

) is produced and wound onto another bobbin.

During such doubling, a heat-resistant oil agent is applied to the pitch fibers in consideration of treatments during infusibility and preliminary carbonization. As the heat-resistant oil agent, alkylphenylpolysiloxane is preferable, and the phenyl group content is 5 to 80%, preferably 10 to 50%.
In addition, the alkyl group is preferably a methyl group, ethyl group, or propyl group, and the same molecule may contain two or more types of alkyl groups. Also, the viscosity is 10 to 10 at 25°C.
00cst is used. Furthermore, an antioxidant as described later can also be added.

Another preferred oil agent that can be used is dimethylpolysiloxane containing an antioxidant, and preferably has a viscosity of 5 to 1000 cst at 25°C. Examples of the antioxidant include amines, organic selenium compounds, phenols, and the like, such as phenyl-α-naphthylamine, dilaurylselenide, phenothiazine, and iron octolate. As mentioned above, these antioxidants can also be added to the alkylphenylpolysiloxane for the purpose of further increasing heat resistance.

Further, as preferred oils, each of the above oils has a boiling point of 60.
It is also possible to use an emulsified product using a surfactant having a temperature of 0° C. or lower. At this time, as the surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene modified silicone,
Polyoxyalkylene-modified silicones and the like may be used.

These oil agents are applied to the pitch fibers in an amount of 0.01 to 10% by weight, preferably 0.05 to 5% by weight, by roller contact, spray coating, foam coating, or the like.

As mentioned above, by applying a heat-resistant oil agent to the pitch fibers that have been doubled, the strength of the pitch fibers becomes significantly stronger and the yarn handling properties are greatly improved.

The pitch fibers produced as described above are unwound from a bobbin and sent to an infusibility furnace.

The temperature inside the infusibility furnace can be set at a constant temperature within the range of 150 to 350°C, but it should be set so that it has a temperature gradient that gradually increases from 150°C to 350°C from the furnace inlet to the furnace outlet. You can also do it.

In addition, the inside of the infusibility furnace is made into an oxidizing atmosphere, and oxidizing gas such as air, oxygen, a mixed gas of air and oxygen, or air and nitrogen is supplied into the infusibility furnace, and a preferable gas is an oxygen concentration of 30 ~90% oxygen rich gas is used.

According to the present invention, the infusibility treatment can be carried out without applying any tension to the fiber bundle, but the slackness of the fiber bundle in the infusibility furnace causes drag scratches caused by rubbing against the furnace bottom and furnace wall. Infusibility should be carried out while applying a tension of 0.0 to 0.2 g per filament in order to prevent the occurrence of carbon weave and to improve the appearance (and improve the physical properties of carbon weave such as tensile strength and tensile modulus). is preferred.

In this way, the infusible fibers are infusible so that the oxygen concentration is 7 to 12% by weight.

According to the present invention, the infusible fibers having an oxygen concentration of 7 to 12% by weight, which have been infusible as described above, are placed in a first stage in an oxygen-containing atmosphere before being subjected to a preliminary carbonization treatment in a preliminary carbonization furnace. Stretching heat treatment is performed.

The temperature in the drawing heat treatment furnace is 100 to 2
00℃ higher temperature is preferable, generally 300~500''
The temperature may be set at a constant temperature within the range of C, for example, 450°C, or it may be set to have a temperature gradient that gradually increases from the furnace inlet to the furnace outlet.
The maximum temperature in this case should not exceed 300-500'C.

For example, the furnace inlet temperature may be set to 350'C, and the temperature may be set to gradually increase to reach the furnace outlet temperature of 500'C. If the heat treatment temperature exceeds 500'C, the oxidation of the infusible fibers will be excessive, which is undesirable. However, it is difficult to get the desired effect.

Further, the inside of the heat treatment furnace is set to have an oxygen-containing atmosphere, and the inside of the furnace is supplied with air, air/oxygen, air and nitrogen, or a mixed gas of nitrogen and oxygen, and the oxygen concentration is preferably 5 to 80%. It is said to be 10-50%. - Generally, air is preferably used. In some cases, the air contains NOy, SO,..., CI2
．． Did you include 2 etc? A mixing gas may also be used.

Further, according to the present invention, the residence time of the infusible fibers in the heat treatment furnace is 1 to 200 seconds, preferably 10 to 200 seconds.
It is 100 seconds. The residence time is set in relation to the above heat treatment temperature.If the residence time exceeds 200 seconds, even if the heat treatment temperature is set to 300℃, the infusible fibers will be oxidized excessively, which is undesirable.If the residence time is less than 1 second, the heat treatment temperature may be Even at 500''C, the surface oxidation of the infusible fibers is insufficient, making it difficult to obtain the expected effect.

Furthermore, according to the present invention, tension is applied to the infusible fibers at the same time as the heat treatment. 0% stretching treatment is applied. Therefore, normally, for a long sword that is made of infusible fiber (=1), 10 to 500 g/3000 filament,
In other words, 0.003 to ○ 1.7 per filament
g.

Stretching may be set by adjusting the magnitude of tension, or may be adjusted by differential movement of two or more rolls.

” Due to the two-layer structure, only the surface of the infusible fiber is selectively oxidized, and the interior of the yarn undergoes thermal polymerization due to high-temperature heat. As a result, the infusible synthetic fiber S1t consisting of many filaments has a high strength. or increase. Therefore, according to the present invention, the infusible fibers are oxidized before preliminary carbonization, or only the surface of the yarn is oxidized, so that the carbon-like
The physical properties of '11 are not deteriorated.

Further, according to the present invention, by oxidizing the surface of the infusible fiber, the degree of fusion sticking on the yarn surface of the infusible fiber in the subsequent pre-carbonization furnace is reduced.

Furthermore, according to the present invention, only the thread surface of the infusible fiber is selectively oxidized, and the interior of the thread undergoes further thermal polymerization, resulting in an increase in the strength of the infusible fiber. The stretching treatment of the fused fibers improves the orientation of the fibers and improves the physical properties of the resulting carbon fibers.

Next, the infusible fibers heat-treated and drawn in this manner are sent to a pre-carbonization furnace and subjected to a pre-carbonization treatment, that is, a second-stage drawing heat treatment in an oxygen-containing atmosphere.

The interior of the preliminary carbonization furnace is set to a maximum temperature of 500 to 700'C. For example, the temperature can be raised stepwise to reach a maximum temperature of 500-700°C, such as 400'C, 500'C0600°C from the inlet to the outlet.Heat treatment temperature If the temperature exceeds 700°C, the oxidation of pre-carbonized 11j iMfI will be excessive, which is undesirable, and if the maximum temperature exceeds 500°C
If it is less than that, the TAE 1 treatment time will be longer or the surface oxidation of the pre-carbonized fibers will be insufficient, making it difficult to obtain the expected effect.

Furthermore, a low concentration oxygen-containing atmosphere is maintained in the heat treatment furnace by supplying a mixture of inert scum and a small amount of oxygen or air. The oxygen concentration is 0.01 to 30%, preferably 0.05 to 10%. Nitrogen or argon gas is used as the inert gas, and NO instead of oxygen or air.

, SO, water vapor, carbon dioxide gas, halogen gas, or strong acid vapor may be used.

Furthermore, according to the present invention, the residence time of the fibers in the pre-carbonization furnace is 20 to 300 seconds, preferably 50 to 2 seconds.
00 seconds. The residence time is set in relation to the heat treatment temperature and oxygen concentration.

In other words, the oxygen content of the low concentration oxygen-containing atmosphere is 0.0
If it is less than 1%, it is too small and the surface of the infusible fiber cannot be effectively oxidized by short-time heating during preliminary carbonization, and on the other hand, if it exceeds 30%, it is too large and a short-time heat treatment is not enough. However, it is not possible to selectively oxidize only the surface of the infusible fiber, and the oxidation progresses to the inside of the fiber, causing problems.

In addition, the heat and treatment time during pre-carbonization of infusible fibers in an atmosphere containing low concentration of oxygen is too short if it is less than 20 seconds, so even if the oxygen content of the atmosphere is increased, the infusible fibers will not be The surface cannot be effectively oxidized, and conversely, if it exceeds 300 seconds, it is too long, and even if the oxygen content of the atmosphere is reduced, oxidation will inevitably occur to the inside of the infusible fiber.

Furthermore, according to the present invention, at the same time as the above heat treatment, tension is applied to the fibers and a stretching process of 5 to 100% is performed. Therefore, the tension applied to the infusible fiber is usually 20
~1000g/3000 filaments, that is, 0°006~0.33g per filament. Stretching may be set by adjusting the magnitude of tension, or may be adjusted by differential movement of two or more rolls.

According to Motoaki, the infusible fibers are heat-treated for a short time in an atmosphere containing low concentration of oxygen in the pre-carbonization furnace, and the surface of the fibers is selectively oxidized to strengthen the surface while pre-carbonizing the fibers. Therefore, it is possible to further draw the infusible fibers in the pre-carbonization furnace, and it is thought that the degree of fusion stickiness of the pre-carbonized fibers is reduced. ``As described above, by carrying out the drawing heat treatment in two stages: after the infusibility treatment and during the preliminary carbonization treatment, the degree of fusion and stickiness of the carbon fibers is reduced to 30% or less. At the same time,
The orientation in the fibers is improved, which in particular increases the thermal conductivity, resulting in yarns with high thermal conductivity.

The fibers thus preliminarily carbonized are then fed to a carbonization furnace and carbonized while being stretched by 1 to 30% in an inert gas atmosphere with a maximum temperature of 2,600 to 3,200°C.

To explain further, the residence time of the fiber in the carbonization furnace is 1
~100 minutes, preferably 2 to 60 minutes. The residence time is set in relation to the heat treatment temperature.

Further, according to the present invention, at the time of carbonization treatment, tension is applied to the fiber at the same time, and stretching treatment is performed by 1 to 30%. Therefore,
Usually, the tension applied to the fiber is 150 to 600.
00g/3'Ooo filament, that is, 0.05 to 20g per filament.

According to the present invention, the stretching heat treatment is performed in two stages: after the infusibility treatment and the preliminary carbonization treatment, and at the same time, the stretching treatment is performed during the carbonization treatment, so that the orientation of the fibers is further significantly improved. In particular, the thermal conductivity is significantly increased, and a yarn with ultra-high thermal conductivity can be obtained. The ultra-high thermal conductivity pitch-based carbon fiber having the above structure according to the present invention cannot be obtained by the -stage or two-stage drawing heat treatment.

With the above manufacturing method, the thermal conductivity in the fiber axis direction is 500 to 15.
00 W/m/, the lamination thickness h (L c
O'02), density (ρ) is 120-5oo, fusion degree is 0-30%, and compressive strength is 0.2-0.4GP'
The ultra-high thermal conductivity pitch-based carbon fiber according to the present invention, which has a tensile strength of 2.5 to 4.5 GPa and a tensile modulus of 700 to 950 GPa, can be suitably obtained.

In this specification, the following measurement method was used to measure the characteristics of carbon fibers.

・Thermal conductivity was measured using a laser flash method on a sample of carbon fiber bundles impregnated with epoxy resin.

・X-ray structural parameters Lamination thickness (L c 002'), Lamination length (L a 1
10) Layer spacing (doo2) is a parameter representing the fine structure of carbon fibers determined by X-ray diffraction method.

Lamination thickness (L c 002) is +7) (0'
02) represents the apparent thickness of the laminated layers on the surface, and it is generally considered that the larger the laminated thickness (L c 002), the better the crystallinity. The stacking length (L a 11.0) represents the length of the stacking of (110) planes in the carbon crystal, and is generally referred to as the stacking length (L a 11.0).
It is assumed that the larger the value (r-allo), the better the crystallinity.
Ru. Further, the layer spacing (doo2) represents the layer spacing of the (002) plane of the crystal, and it is considered that the smaller the layer spacing (doo2), the better the crystallinity.

Lamination thickness (L c 002), lamination length (L a 11
0), the interlayer spacing (doo2) is determined by powdering carbon fiber ^, 11 in a mortar and determining t by prefecture according to the school method "Lattice constant of artificial graphite and crystallite size 7μ11 method" (Il!i!
It was calculated using the following formula.

LcDO2=toλ/βcosO L a 11.0 = Kλ/13'cosθ゛doo
2 -n/2 sin eHere, K=1.0.
Travel = 1.5418 person O: Obtained from the diffraction angle 2θ of the (0[12) plane.

0° (determined from the diffraction angle 2θ of the 1,10j plane.

β - Half width of the diffraction band of the (002) plane determined by correction.

Half width of diffraction band of (110) plane determined by β' correction.

・Density (ρ) It was measured using a density gradient tube.

・1.5mm carbon fiber bundle made of filament with a fusion degree of 3000
Cut out the Nakabatake and add it to ethanol (crushed, 30 ml).
Air is blown for seconds, and then the total number (N) of fused and stuck filaments is counted under a microscope at a magnification of 20 times, and is determined by the following formula.

Melting adhesion degree = (N/3000:)X100 (%)・Compressive strength Kemple made by impregnating carbon fiber bundles with epoxy fat is AST
It was determined according to MD341D.

EXAMPLES Hereinafter, the method for producing ultra-high thermal conductivity pitch-based carbon fiber according to the present invention will be described with reference to Examples.

Example 1 In producing pitch fiber, optically anisotropic phase was reduced to 45%
A carbonaceous pitch having a softening point of 226° C. was used as a precursor pitch. This precursor pitch was centrifuged to successively separate pitches containing many optically anisotropic phases and pitches containing many optically isotropic phases, and each was extracted.

The obtained optical anisotropy 1 (j, including many phases and the pitch is
It contained 100% of an optically anisotropic phase, had a softening point of 270°C, and 7 volumes of quinoline was 28.0% by weight.

The carbon fiber pitch was passed through a melt spinning machine having a 500-hole spinneret (nozzle hole diameter: 0.3 mm), and 335
'C was spun.

The 500 spun filaments [.
A focusing oil was supplied in a proportion of 500% by weight to form a pitch fiber consisting of 500 filaments. As an oil agent, 25
Medilphgonylbolysiloxene having a viscosity of 14 cst at °C was used.

The pitch fibers were wound onto a stainless steel bobbin with a diameter of 210+ nm and a width of 200 mm that was installed at the bottom of the nozzle and rotated at high speed, and spun for 10 minutes at a winding speed of about 500 m/min. bobbin] The pitch of the traverse per revolution was 10 mm/1 revolution. No thread breakage A1 occurred during spinning.

Next, the six bobbins wound with pitch cilia (() were unwound, and the threads were combined using an oiling roller without applying a heat-resistant oil to form a pitch fiber consisting of 3000 filaments. There's a conch shell on a made bobbin.

During yarn doubling, 40 cst medylphenylbolysiloxene (phenyl group content: 45 mol %) was used at 25°C as an oil agent. The weight of the fiber was 0.5% based on the yarn.

While unwinding the thus obtained bobbin-wound pitch fiber fill- from the bobbin, an oxygen-rich atmosphere (oxygen/nitrogen 2 60,740) with a temperature gradient of 180°C at the furnace inlet and 295°C at the maximum temperature was maintained. It was introduced continuously in a linear manner into the melting furnace. The temperature increase rate was 6° C./min, and the infusibility time was 19 minutes. The tension applied to the fiber is 0.0 per liter filament.
07g (20 for a fiber bundle of 3000 filaments)
g). The oxygen concentration of the infusible fiber after infusibility is 9.
It was 5% by weight.

During the infusibility process, the pitch fibers were unraveled from the bobbin smoothly, and the infusibility treatment was carried out smoothly without any breakage of the fiber bundle in the infusibility furnace.

The infusible fibers thus obtained were fed to a heat treatment furnace maintained at 450'C before being passed to a pre-carbonization furnace. The fiber has a tension of 0.0 per filament.
07g added. Air was introduced into the furnace.

With the above configuration, the time required to heat treat the infusible fibers was 25 seconds.

The heat treatment was carried out smoothly without any fiber breakage in the heat treatment furnace. The stretching ratio of the yarn in this heat treatment was 20%.

The fibers heat-treated in this oxygen-containing atmosphere are continuously introduced in a linear manner into a pre-carbonization furnace in an oxygen-containing atmosphere (oxygen/nitrogen = 5/95) with a temperature gradient of 400°C at the furnace inlet and 600°C at the maximum temperature. did. A tension of 0.017 g per filament was applied to the fibers, and the stretching ratio was 15%. Preliminary carbonization time was 25 seconds. Although the treatment was continued for 24 hours, no yarn breakage or breakage occurred in the furnace during this period.

The pre-carbonized fibers were continuously introduced in a linear manner into a carbonization furnace in an argon gas atmosphere with a maximum temperature of 2800"C. A tension of 0.3 g per filament was applied to the fibers, and the drawing rate was 9. %. Carbonization time was 10 minutes. Thread diameter was 8.3 μm.

The properties of this carbon fiber are shown in Table 1.

Example 2 An infusible fiber was produced using the same materials and method as in Example 1, and the same as in Example 1, the infusible fiber was held at 450'C before being threaded into a pre-carbonization furnace. It was then supplied to a heat treatment furnace. The fiber has a tension of 0.00 per filament.
7'g was added, and heat treatment was performed for 25 seconds. Air was introduced into the furnace.

The heat treatment was carried out smoothly without any fiber breakage in the heat treatment furnace. The stretching ratio of the yarn in this heat treatment was 20%.

The fibers heat-treated in this oxygen-containing atmosphere were produced in the same manner as in Example 1 (furnace inlet temperature: 4.00°C; maximum temperature: 60°C; oxygen-containing atmosphere with a temperature gradient of 0°C (oxygen/nitrogen = 5/9
5) was continuously introduced in a linear manner into the preliminary carbonization furnace. At this time, unlike in Example 1, the fibers contained 0.00% per filament.
A tension of 0.067 g was applied and the stretching ratio was 19%. Preliminary carbonization time was 25 seconds. Although the treatment was continued for 24 hours, no yarn breakage or breakage occurred in the furnace during this period.

This pre-carbonized fiber was continuously introduced in a linear manner into a carbonization furnace in an argon gas atmosphere with a maximum temperature of 3000°C.

The fibers contain 0, . A tension of 4 g was applied and the stretching ratio was 10%. Carbonization time was 12 minutes. The thread diameter was 8-1 ILLm.

The properties of this carbon fiber are shown in Table 1.

Comparative Example 1 Infusible fibers and pre-carbonized fibers were obtained using the same materials and methods as in Example 2, and the pre-carbonized fibers were continuously introduced in a linear manner into a carbonization furnace in an argon gas atmosphere with a maximum temperature of 2800°C. and carbonized. Carbonization time was 10 minutes. No tension was applied to the fibers during the carbonization process. The thread diameter was 8.4 μm.

The properties of this carbon fiber are shown in Table 1.

Comparative Example 2 An infusible fiber was produced using the same materials and method as in Example 1, and the infusible fiber was directly exposed to an oxygen-containing atmosphere (oxygen/nitrogen = 5/ 95), was continuously introduced in a linear manner into a pre-carbonization furnace, and pre-carbonization was performed. The preliminary carbonization furnace had a temperature gradient with a furnace inlet temperature of 400°C and a maximum temperature of 900°C, and the preliminary carbonization treatment was performed for 250 seconds. A tension of 0.017 g per filament is applied to the fiber, and the stretching ratio is 1.
It was 5%.

This pre-carbonized fiber was continuously introduced in a linear manner into a carbonization furnace in an argon gas atmosphere with a maximum temperature of 2800'C. A tension of 0.3 g per filament was applied to the fibers, and the stretching ratio was 8%. Carbonization time was 10 minutes. The thread diameter was 9.1 μm.

The properties of this carbon i & fiber are shown in Table 1.

Comparative Example 3 Infusible fibers were produced using the same materials and methods as in Example 1, and similarly to Example 1, the infusible fibers were supplied to a heat treatment furnace maintained at 450°C. A tension of 0.007 g per filament was applied to the fibers, and heat treatment was performed for 25 seconds. Air was introduced into the furnace.

The infusible fibers obtained by heat treatment in this manner were continuously introduced in a linear manner into a carbonization furnace in an argon gas atmosphere with a maximum temperature of 2800° C. without being subjected to preliminary carbonization stretching treatment.

The fibers were subjected to a tension of O', 3'g per filament, and the draw ratio was 10%. Carbonization time was 15 minutes. The thread diameter was 8.9 μm.

The properties of this carbon fiber are shown in Table 1.

Menu sitting position 1 As explained above, the ultra-high thermal conductivity pitch-based carbon fiber according to the present invention has
It has extremely high thermal conductivity, high compressive strength, and excellent yarn handling properties.
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Claims (1)

[Claims] 1) Thermal conductivity in the fiber axis direction is 500 to 1500 W/m/
K, lamination thickness (Lc002)/density (p
) is 120 to 500, a fusion degree is 0 to 30%, and a compressive strength is 0.2 to 0.4 GPa. 2) Tensile strength is 2.5 to 4.5 GPa, tensile modulus is 7
The ultra-high thermal conductivity pitch-based carbon fiber according to claim 1, which has a thermal conductivity of 00 to 950 GPa. 3) Pitch fibers obtained by spinning carbonaceous pitch are made infusible, and the infusible infusible fibers are passed through an oxygen-containing atmosphere at 300 to 500°C for 1 to 200 seconds to undergo a stretching heat treatment of 5 to 100%. application, followed by a maximum temperature of 500-700℃
5 to 10 times for 20 to 300 seconds in an oxygen-containing atmosphere of
0% stretching preliminary carbonization treatment, then maximum temperature 260
A method for producing pitch-based carbon fibers with ultra-high thermal conductivity, characterized by carrying out carbonization while performing a stretching treatment of 1 to 30% in an inert gas atmosphere at 0 to 3,200°C.