JP4323713B2 - Fiber assembly and composite material containing the same - Google Patents

Description

【００８８】
【発明の効果】
この発明によると、極細気相成長炭素繊維の縺れ及び絡みが少なくて極細気相成長炭素繊維に大径気相成長炭素繊維が分散してなり、極細気相成長炭素繊維が適度に接触してなる繊維集合体を提供することができる。
【００８９】
この発明によると、前記繊維集合体を母材中に分散してなり、電気的特性、機械的特性及び熱的特性の向上した複合材料を提供することができる。
【図面の簡単な説明】
【図１】図１はこの発明に係る繊維集合体を製造することのできる気相成長炭素繊維製造装置を示す説明図である。
【図２】図２は、図面代用写真としての、実施例１において得られた繊維のＳＥＭ写真である。
【図３】図３は、図面代用写真としての、実施例１において得られた繊維のＳＥＭ写真である。
【図４】図４は、図面代用写真としての、実施例１において得られた繊維のＳＥＭ写真である。
【図５】図５は、図面代用写真としての、実施例１において得られた繊維のＳＥＭ写真である。
【図６】図６は、図面代用写真としての、実施例１において得られた繊維のＳＥＭ写真である。
【図７】図７は、図面代用写真としての、実施例１において得られた繊維のＳＥＭ写真である。
【符号の説明】
１…気相成長炭素繊維製造装置、２…縦型炉心管、３…加熱装置、４…原料液タンク、５…原料液供給ポンプ、６…気化器、７…第１ガス流量計、８…予熱器、９…原料ガス供給ノズル、１０…第２ガス流量計、１１…第２ガス供給器、１２…整流器、１３…第３ガス流量計、１４…第３ガス供給部、１５…案内ガス流量計、１６…案内ガス供給室、１７…整流器、１８…排出管、１９…シール水槽、２０…シール水管、２１…繊維捕集槽、２２…希釈ガス導入管、２３…水噴霧器、２４…第１仕切板、２５…第２仕切板、２６…定水位排水孔、２７…排気ファン連絡管、２８…貯留水、２９…繊維（製品）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fiber assembly and a composite material containing the same, and more particularly to a fiber assembly that can bring out fiber characteristics with less fiber twisting and entanglement and a composite material containing the same.
[0002]
[Prior art]
Vapor-grown carbon fiber has excellent electrical conductivity, slidability, radio wave absorption, chemical stability, etc. in addition to its mechanical properties. However, it has not yet been implemented in large quantities.
[0003]
What is important for the production of the composite material is the dispersion state of the filler in the base material.
[0004]
For example, when the filler is powder, secondary agglomeration occurs when the particle size is small, and no matter how small the diameter of the primary particle, the effect is actually obtained only as the diameter of the secondary agglomerated particle. Is seen. In the case where the filler is a fiber, it is more troublesome because it becomes supple and easily entangled when the fiber diameter becomes small.
[0005]
In particular, vapor-grown carbon fibers having a fiber diameter of 100 nm or less, particularly 50 nm or less, are obtained in a curved and entangled state from the time of fiber production, so it is difficult to unravel this and disperse it uniformly in the base material. It was.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a fiber assembly that is an aggregate of ultrafine vapor grown carbon fibers but can be present in an elongated form with little twisting and entanglement.
[0007]
Another object of the present invention is to provide a fiber assembly that is an aggregate of ultrafine vapor-grown carbon fibers and that can exhibit electrical conductivity, thermal conductivity, and mechanical properties with less twisting and entanglement. There is.
[0008]
An object of the present invention is to provide a composite material having excellent electrical conductivity, thermal conductivity, and mechanical properties by using a fiber assembly with less twisting and entanglement.
[0009]
[Means for Solving the Problems]
  Means for solving the problems are as follows:
(1) containing an aggregate of small-diameter vapor-grown carbon fibers and an aggregate of large-diameter vapor-grown carbon fibers, and an average diameter of the aggregate of small-diameter vapor-grown carbon fibers is 3 to 50 nm, The average diameter of the aggregate of the large-diameter vapor-grown carbon fibers is60-300nmInThe
  The aggregate of the large-diameter vapor-grown carbon fibers has a volume percentage of 0.1 to 30% of the total vapor-grown carbon fibers.A fiber assembly characterized by
(2)  The aggregate of the small-diameter vapor grown carbon fibers has an average aspect ratio of at least 30 and the aggregate of the large-diameter vapor-grown carbon fibers has an average aspect ratio of 2 to 100. The average aspect ratio of the aggregate of diameter vapor-grown carbon fibers does not exceed the average aspect ratio of the aggregate of small-diameter vapor-grown carbon fibers(1)It is a fiber assembly of description,
(3)  The aggregate of the small-diameter vapor-grown carbon fiber and the aggregate of the large-diameter vapor-grown carbon fiber are both graphitized fibers that are heat-treated at 1500 to 3500 ° C.(1) or (2)It is a fiber assembly of description,
(4)  Said (1)-(3)A composite material comprising the fiber assembly according to any one of the above.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The fiber assembly according to the present invention has a fine vapor-grown carbon fiber having an average diameter of 3 to 50 nm, preferably 5 to 30 nm, and an average diameter of more than 50 and not more than 500 nm, preferably 60 to 300 nm. It contains a large-diameter vapor grown carbon fiber.
[0011]
If the average diameter of the small-diameter vapor-grown carbon fibers is within the above range, and the average diameter of the large-diameter vapor-grown carbon fibers is within the above-mentioned range, the ultra-fine vapor-grown carbon fibers are twisted or entangled with each other. However, the mixing of large-diameter vapor-grown carbon fibers is reduced to such an extent that it can be practically used, and the number of contact points between the fibers increases, and the conductivity is good.
[0012]
The aspect ratio of the small diameter vapor growth carbon fiber is usually 30 to 20,000, preferably 50 or more.
[0013]
When the aspect ratio is within the above range, the number of contact points of the fibers is increased, and the electrical conductivity of the composite material is increased, so that the object of the present invention can be achieved well. When the aspect ratio is less than 30, there is a slight problem in terms of conductivity. There is a slight problem with the representation of the upper limit of the aspect ratio. In other words, it is difficult to actually measure an aspect ratio of 20,000, and the numerical values of aspect ratios of 10,000, 20,000, and 30,000 should be said to be infinite experimentally, but are finite fibers. This is because the value is about 20,000. This will be described below.
[0014]
For experiments measuring a fiber with a diameter of 10 nm and an aspect ratio of 20,000:
The length of this fiber is 10 nm × 20,000 = 200,000 nm = 200 μm. In order to confirm this fiber, a scanning electron microscope magnification of 30,000 to 50,000 times is necessary. (Fibers can be seen in a thickness of 10 nm × 3 to 50,000 = 0.3 to 0.5 mm.) At lower magnifications, it is difficult to discriminate each fiber. At that time, the length appears to be 200 μm × 30,000 to 50,000 = 6 to 10 m. If the length of one field of view is 10 cm, one fiber exists over 60 to 100 photographs. Since one fiber does not exist alone but is one in the fiber mass, it is not always in a position where the surface is easy to see. Therefore, it is practically impossible to observe from one end to the other end of one fiber.
[0015]
The aspect ratio of 10,000 or 20,000 is estimated from the situation in which only one or two ends can be seen in 100 fibers that can be seen in one field of view.
[0016]
The aspect ratio of the large-diameter vapor grown carbon fiber is usually 2 to 100, preferably 5 to 50.
[0017]
When the aspect ratio of the large-diameter vapor-grown carbon fiber is within the above range, the aggregate of the small-diameter vapor-grown carbon fiber can be satisfactorily defibrated with the large-diameter vapor-grown carbon fiber, and the composite material When manufacturing, the dispersibility of the small-diameter vapor-grown carbon fiber in the base material can be improved.
[0018]
Even if the large-diameter vapor grown carbon fiber is within the aspect ratio, it is preferable that the large-diameter vapor-grown carbon fiber is not longer than the small-diameter vapor-grown carbon fiber. That is, the average aspect ratio of the large diameter vapor grown carbon fiber should not exceed the average aspect ratio of the small diameter vapor grown carbon fiber.
[0019]
The large-diameter vapor grown carbon fiber has a volume percentage of 0.1 to 30%, preferably 0.2 to 20%, most preferably 0.3 to 15% of the whole vapor grown carbon fiber. is there.
[0020]
When the number of the large-diameter vapor-grown carbon fibers is within the above range, for example, the mechanical properties, conductivity, and thermal conductivity of the resin composite material are remarkably improved. The reason is that, when kneaded with resin, the large-diameter vapor-grown carbon fiber becomes a stick and can slightly stretch the entanglement of the small-diameter vapor-grown carbon fiber. The possibility that the fibers are subjected to stress during kneading to relieve stress on the fine vapor grown carbon fibers and prevent breakage is increased, and as a result, contact between the fine vapor grown carbon fibers is ensured. It is estimated that the mechanical properties can be maintained while exhibiting the properties and thermal conductivity. In other words, if the volume percentage of the large-diameter vapor-grown carbon fiber is less than 0.1% of the total vapor-grown carbon fiber or exceeds 30%, the small-diameter vapor-grown carbon fibers are entangled and entangled with each other. As a result, the conductivity and the like may be lowered, and the mechanical properties may be deteriorated.
[0021]
Since the volume of the large-diameter vapor grown carbon fiber is large even if the number of the fiber aggregate is small, the volume occupied by the large-diameter vapor grown carbon fiber in the fiber aggregate according to the present invention is large. It becomes important to control by percentage. However, in actual measurement, it is necessary to measure the diameter (thickness) of each fiber and calculate the volume percentage from this.
[0022]
In order to easily obtain the volume percentage, the ratio of the average diameter d (L) of the large diameter vapor grown carbon fiber to the average diameter d (S) of the small diameter vapor grown carbon fiber ρ = d (L) / d ( It is good to prepare a relational diagram of the number percentage and volume percentage of large-diameter vapor-grown carbon fibers when S) is different and use it.
[0023]
Note that the small-diameter vapor-grown carbon fiber and the large-diameter vapor-grown carbon fiber in the present invention are both hollow, and are carbon fibers in which the graphite network surface is oriented in parallel with the fiber axis in an annual ring shape or a spiral shape. is there.
[0024]
The fiber aggregate containing the small-diameter vapor-grown carbon fiber and the large-diameter vapor-grown carbon fiber can be produced by simultaneously producing them in the same reaction apparatus when producing the vapor-grown carbon fiber. Even if the method of mixing these after producing small diameter vapor growth carbon fiber and large diameter vapor growth carbon fiber separately, both do not mix easily, the effect like this invention is I can't get it.
[0025]
The vapor growth carbon fiber production apparatus for obtaining the fiber assembly of the present invention includes, for example, a specification according to FIG. 1 in JP-A-8-301699, FIG. 1 in JP-A-11-107052 and Japanese Patent Application No. 11-198731. 1 attached to the specification, FIG. 1 and FIG. 3 attached to the specification related to Japanese Patent Application No. 10-353628, and FIG. 1 and FIG. 2 attached to the specification related to Japanese Patent Application No. 10-353629, 1 and FIG. 2 attached to the specification relating to 11-247710, FIG. 1 attached to the specification relating to Japanese Patent Application No. 11-290505, etc.
[0026]
These apparatuses are vertical-type vapor-grown carbon fiber manufacturing apparatuses having a source gas (a source vapor obtained by diluting source vapor for generating fibers with a carrier gas) supply nozzle and a gas supply system surrounding it. Furthermore, the apparatus is designed so that vapor grown carbon fibers generated in the reaction tube are continuously discharged out of the reaction tube. When the produced fiber adheres to the reaction tube wall, not only a fiber having a diameter of several to several tens of μm can be obtained but also the reaction tube can be blocked. Therefore, by rectifying the gas supplied into the reaction tube or smoothly discharging the gas after reaction together with the guide gas, the gas flow in the reaction tube is stabilized and the generated fibers are prevented from adhering to the reaction tube wall. These are the ideas of the inventive device.
[0027]
The fiber assembly of the present invention can be obtained by using these devices and selecting vapor growth carbon fiber production conditions.
[0028]
FIG. 1 shows another example of an apparatus for obtaining the fiber assembly of the present invention. The idea is the same as above.
[0029]
As shown in FIG. 1, this vapor growth carbon fiber production apparatus 1 includes a vertical furnace core tube 2, a heating device 3, a raw material liquid tank 4, a raw material liquid supply pump 5, a vaporizer 6, and a first gas flow meter. 7, preheater 8, source gas supply nozzle 9, second gas flow meter 10, second gas supply device 11, rectifier 12, third gas flow meter 13, third gas supply unit 14, guide gas flow meter 15, guidance Gas supply chamber 16, rectifier 17, discharge pipe 18, seal water tank 19, seal water pipe 20, fiber collection tank 21, dilution gas introduction pipe 22, water sprayer 23, first partition plate 24, second partition plate 25, constant water level A drain hole 26 and an exhaust fan communication pipe 27 are provided.
[0030]
As shown in FIG. 1, a vertical reactor core tube 2 is formed by, for example, a cylindrical or rectangular tube-shaped vertical reaction tube having the same internal cross-sectional shape in the direction orthogonal to the axis along the axis. Have
[0031]
The vertical core tube 2 is designed to thermally decompose the catalytic metal source and the carbon source gas supplied together with the carrier gas.
[0032]
This vertical reactor core tube 2 is a so-called reaction tube, which is heated to a high temperature necessary for decomposition of the carbon source gas and the catalytic metal source gas as will be described later, and as a carrier gas, for example, hydrogen gas as will be described later. Therefore, it is preferably formed of a heat resistant material that can withstand high temperature hydrogen embrittlement reaction and carburization reaction, for example, ceramic such as silicon carbide, silicon nitride, alumina, mullite.
[0033]
The heating device 3 only needs to be able to raise the inside of the vertical furnace core tube 2 to, for example, 1000 ° C. or more, and heating by an electric heater or gas combustion is exemplified.
[0034]
The raw material containing the catalytic metal source for generating the vapor growth carbon fiber is supplied from the raw material liquid tank 4 by the raw material liquid supply pump 5, gasified by the vaporizer 6, and then supplied from the first gas flow meter 7. One carrier gas passes through the preheater 8 and is sent from the source gas supply nozzle 9 to the vertical furnace core tube 2. Add liquid hydrocarbons such as benzene, toluene, and hexane to the raw material liquid to make a carbon source, or add gaseous hydrocarbons such as methane, ethane, ethylene, acetylene, propane, and natural gas to the first gas. It may be a source. As the first gas, only a carrier gas (for example, hydrogen gas) or a carbon source gas (for example, natural gas) may be used, but a carrier gas and a carbon source gas may be mixed and used. A catalytic metal source is a substance that can be evaporated and thermally decomposed at high temperatures to form metal (particularly transition metal) particulates. Illustrative examples include organic metal compounds such as ferrocene, nickelocene, cobaltcene, iron carbonyl, and acetonate iron, and inorganic metal compounds such as iron chloride. Vapor-grown carbon fibers are generally considered to be produced with transition metal fine particles having a diameter of about 20 nm as a nucleus. At that time, since the fiber formation is promoted when sulfur is present, a sulfur compound such as thiophene or hydrogen sulfide is generally added as a promoter.
[0035]
As the catalyst source / co-catalyst source, those conventionally used may be used, and as the catalyst metal source, JP-A-60-54998, page 3, upper left column, line 9 to upper right column of the same page. Organic transition metal compounds described in the lower row, organic transition metal compounds described in paragraph [0059] of JP-A-9-324325, organic transitions described in paragraph [0049] of JP-A-9-78360 Examples of the co-catalyst include sulfur-containing heterocyclic compounds described in paragraph No. [0051] of JP-A-9-78360 and paragraph No. [0061] of JP-A-9-324325. Mention may be made of compounds and sulfur compounds.
[0036]
The mixed gas supplied from the source gas supply nozzle (including a catalyst source and a promoter source, including a carbon source and including a carrier gas) is referred to as a source gas.
[0037]
The second gas supply unit 11 surrounding the source gas supply nozzle is supplied with a carrier gas such as hydrogen, a carbon source gas such as natural gas, or a mixture thereof from the second gas flow meter 10. A rectifier 12 (such as a ceramic or refractory metal honeycomb) is installed in the second gas supply device 11 so as to rectify the second gas and supply the raw material gas to the core tube 2 while surrounding it. .
[0038]
The second gas serves to form carbon nanofibers while being diffusively mixed with the source gas.
[0039]
Furthermore, a carrier gas such as hydrogen, nitrogen, or argon is supplied from the third gas flow meter 13 to the third gas supply unit 14. The third gas supply unit 14 is a gap between the outer wall of the second gas supply unit and the inner wall of the core tube, and is a gap of several mm to several tens of mm. Although it is most preferable to install a rectifier such as a honeycomb made of ceramic or heat-resistant metal, the rectifier may be omitted particularly in a narrow case. The third gas flows down the core tube wall and prevents the product from the raw gas from reaching the tube wall and adhering. For the purpose of the third gas, the third gas does not include a carbon source. When hydrogen is used, the catalyst source concentration, carbon source concentration, and product concentration in the vicinity of the core tube wall will be lowered to prevent the reactant from adhering to the core tube wall. Although it is obtained, the effect may be weakened in terms of preventing adhesion to the wall. When nitrogen and argon are used, the wall adhesion is slightly reduced, but the product quality is reduced by non-fibres such as soot.
[0040]
The source gas, the second gas, and the third gas flow down through the reaction tube and reach the vicinity of the inlet of the discharge tube 18 in a state that includes vapor-grown carbon fibers generated in the gas (hereinafter referred to as post-reaction gas). To do.
[0041]
Around the discharge pipe, a guide gas such as nitrogen and argon is supplied from the guide gas flow meter 15 through the guide gas supply chamber 16 and the rectifier 17 so as to face the post-reaction gas. The post-reaction gas surrounded by the guide gas is guided into the fiber collection box 21 from the discharge pipe, and the fibers are collected separately.
[0042]
The discharge pipe and the fiber collection box 21 are connected via a seal water pipe 20 having a seal water tank 19. The fiber collection tank 21 is connected to the exhaust fan communication pipe 27 and exhausts the outlet of the discharge pipe 18 to draw out the gas after the guide gas surrounding reaction. By adjusting the height of the sealing water tank (head) and the diameter of the sealing water pipe, it is possible to draw out the gas after the reaction of the guide gas by the flowing water.
The fiber collection box 21 includes a dilution gas introduction pipe 22, a water sprayer 23, a first partition plate 24, a second partition plate 25, a constant water level drain hole 26, and an exhaust fan communication pipe 27. The grown carbon fiber is separated and removed, and the reaction gas is treated safely.
[0043]
The carbon source gas is not particularly limited as long as it is a compound capable of generating carbon by pyrolysis to generate a carbon fiber material such as vapor-grown carbon fiber, particularly carbon nanofiber and carbon nanotube. Examples of usable carbon sources include carbon compounds described in JP-B-60-54998, page 2, lower left column, line 4 to same page, lower right column, line 10; JP-A-9-324325, paragraph number Examples thereof include organic compounds described in [0060] and organic compounds described in paragraph [0050] of JP-A-9-78360.
[0044]
Since a large amount of pyrolytic carbon is contained when the fiber grows when it grows in thickness, the concentration of the carbon source gas is reduced to produce the ultrafine vapor-grown carbon fiber in this invention. It is better to increase the concentration. Therefore, the ratio of the carbon source gas and the catalyst metal source gas charged into the vertical core tube 2 to the total mixed gas is preferably 0 to 40% and 0.01 to 40%, respectively, more preferably each. 0.5 to 10% and 0.05 to 10%. Here, the concentration of the carbon source gas may be 0 because the carbon source gas is not necessarily required when, for example, the organometallic compound that is the catalyst metal source contains sufficient carbon in the molecule. Meaning. Therefore, in the present invention, the carbon source and the catalytic metal source may be the same compound.
[0045]
As the carrier gas, a known gas used for the production of carbon fiber material such as vapor-grown carbon fiber, carbon fiber, carbon nanofiber, carbon nanotube, etc. can be appropriately employed, and hydrogen is mentioned as a preferred example. Can do.
[0046]
Furthermore, in the vapor-grown carbon fiber production apparatus 1 according to the present invention, a fiber assembly using a carrier gas, an organometallic compound and a carbon source gas as described in JP-A-60-54998. Can be manufactured.
[0047]
The source gas supply nozzle 9 has a double-pipe structure, and has a jacket structure (not shown) in which the source gas flows on the inner side (center) and the outer side flows a cooling gas. A cooling gas such as nitrogen or air is discharged to the outside rather than inside the core tube. The raw material gas is supplied to the core tube after cooling to a temperature suitable for causing the vapor-grown carbon fiber formation reaction in the core tube without causing decomposition of the catalyst metal source compound. A second gas supplier 11 is disposed outside the source gas supply nozzle 9. A rectifier 12 is installed in the second gas supply device, and a second gas, for example, hydrogen or methane is made into a laminar flow in the vertical furnace core tube 2 so as to surround and blow out the source gas. The second gas supplier rectifies the second gas and preheats the second gas with heat from the core tube wall. The source gas supply nozzle can be easily cooled because the second gas supplier absorbs and blocks heat from the core tube wall. The third gas supply unit is a gap between the outer wall of the second gas supply unit and the inner wall of the core tube 2. The third gas, for example hydrogen, is formed so as to flow down in a laminar flow state along the inner wall of the vertical core tube 2. A rectifier for the second gas supply device (such as a ceramic or metal honeycomb) may also be installed in the third gas supply unit. A dead space is formed immediately below the cooling jacket portion of the raw material supply nozzle 9 in the vertical furnace core tube 2.
[0048]
The heating device 3 has a vertical reactor core tube 2 at a temperature sufficient to cause the catalytic metal source compound decomposition / catalyst particle generation reaction and the ultrafine vapor phase growth carbon fiber generation growth reaction with the carbon source gas in the vertical reactor core tube 2. It is formed so that the inside can be heated.
[0049]
The heating temperature in the vertical furnace core tube 2 by the heating device 3 is 900 to 1300 ° C., particularly 1000 to 1250 ° C., more preferably 1050 to 1200 ° C. It is. Furthermore, in the vertical furnace core tube, the inside of the vertical furnace core tube from the same height as the source gas supply nozzle to the same height as the upper opening is maintained at a constant temperature within the above temperature range. Thus, it is preferable to adjust the heating device. When a thin vapor-grown carbon fiber is produced in the vertical core tube 2 adjusted to such a temperature, the fine vapor-grown carbon fiber is obtained at a high production rate without the fibers adhering to the inner wall of the core tube. It is done.
[0050]
As the vertical core tube 2 and the heating device 3, the furnace core tube and the heater in the reactor described in JP-A-9-78630, JP-A-9-229918, and JP-A-9-324325 are suitable. Can be used to.
[0051]
The guide gas supply chamber 16 is provided in the lower part of the vertical core tube 2. The guide gas supply chamber 16 is supplied with an inert gas such as a nitrogen gas through a guide gas flow meter 15.
[0052]
The discharge pipe 18 faces the heat equalizing section in the vertical core tube 2, passes through the upper opening that opens upward, the guide supply chamber 16, and penetrates the bottom thereof. And a tube main body extending into the fiber collection tank 21 and a lower opening that opens toward the stored water 28 inside the fiber collection tank 21 at the lower end of the pipe main body 18. . The discharge pipe 18 is disposed in the vertical core tube 2 so as to have a center line that coincides with the center line of the source gas supply nozzle 3.
[0053]
Vapor-grown carbon fibers have a very high rate of fiber elongation and a very slow rate of fiber thickening. When citing literature values, the speed at which the fibers extend from the catalyst particles is about 1 mm / min = 17 μm / sec, but the speed at which the fibers are thickened is said to be 5 μm / hr = 1.4 nm / sec or less (Endo).・ Oyama, Textile Society Journal,32, 177 (1976)).
[0054]
In the method of the present invention, the average time that the source gas (including the case where the second gas or the third gas is added) stays in the reaction region is several seconds or less. That is, although a small diameter vapor growth carbon fiber is produced, a large diameter vapor growth carbon fiber is difficult to produce, and it is difficult to obtain the product of the present invention when producing the vapor growth carbon fiber.
[0055]
The estimation of how the fiber aggregate containing the small diameter vapor grown carbon fiber and the large diameter vapor grown carbon fiber is obtained will be described below.
[0056]
First, when a raw material gas is supplied from the raw material gas supply nozzle 9 into the vertical furnace core tube 2, the metal catalyst source in the raw material gas is immediately decomposed to form catalyst particles, acting on the carbon source gas, and vapor phase growth. Carbon fiber is produced. The produced vapor growth carbon fiber grows in the length direction and descends toward the upper opening of the discharge pipe 18 together with the carrier gas (the length reaction time is at most 1 second from the length of the fiber). Is considered within).
[0057]
At this time, a dead space (not shown) is provided immediately below the cooling jacket of the raw material supply nozzle in the vertical furnace core tube 2. Then, the second gas is jetted down from the second gas supply device 11 along the wall of the vertical reactor core tube 2 across the dead space, while the source gas is jetted from the source supply nozzle 9, Airflow turbulence occurs in the dead space. A part of the vapor growth carbon fiber formed directly under the source gas supply nozzle 9 is sucked into the dead space due to the turbulence of the air current, and stays in the dead space for a certain time. A part of the vapor-grown carbon fibers staying in the dead space grows in thickness to form a large-diameter vapor-grown carbon fiber. When the large diameter vapor grown carbon fiber has an appropriate thickness or lump, it flows down from the dead space and is led to the discharge pipe together with the small diameter vapor grown carbon fiber.
[0058]
It has been confirmed by observations of the present inventors that a fiber lump having a diameter of several mm drifts in this dead space for several seconds to several tens of seconds.
[0059]
On the other hand, the guide gas supplied to the guide gas supply chamber 16 rises in the vertical core tube 2 along the outer wall of the discharge pipe 18. In this ascending process, the guide gas is heated by the heating device 3.
[0060]
When the rising guide gas reaches the upper opening of the discharge pipe 18, it is sucked into the upper opening. The guide gas is sucked from the upper opening because the air flow in the exhaust pipe 18 becomes faster than the air flow in the vertical core tube 2 due to the water flow ejected from the seal water pipe 20 or the exhaust from the exhaust fan communication pipe 27. Because.
[0061]
The gas (post-reaction gas) containing the vapor-grown carbon fiber that has descended along the central axis in the interior of the vertical core tube 2 reaches the upper portion of the upper opening of the discharge pipe 18 and guide gas together with the carrier gas. It becomes a state wrapped in and is sucked into the upper opening.
[0062]
At this time, the upper opening of the discharge pipe 18 has a funnel shape, and since the descending carrier gas and the descending vapor-grown carbon fiber-containing gas and the guide gas are merged, air current disturbance or partial circulation is caused. appear. Due to the turbulence or partial circulation of the air flow, the air suspension time of some vapor-grown carbon fibers becomes longer. As a result, some vapor-grown carbon fibers floating in the air cause growth in thickness (a funnel-like shape and vigorous air flow agitation in the upper part thereof have been confirmed).
[0063]
Eventually, the vapor-grown carbon fiber passing through the discharge pipe 18 has an ultrafine vapor-grown fiber as a result of little thickness growth and a large-diameter vapor-grown carbon as a result of thickness growth. A fiber mixture is formed by mixing the fibers.
[0064]
This mixture falls from the lower opening of the discharge pipe 18 into the stored water 28 in the fiber collecting tank 21 together with the water flow. The true specific gravity of the vapor grown carbon fiber is 1 or more, but the fiber lump is bulky and 0.1 or less, so it does not settle in the stored water 28 and floats on the stored water 28. The fibers that do not float on the stored water 28 and rise to the space in the fiber collecting tank are forcibly dropped onto the stored water 28 by the shower water sprayed from the water sprayer 23.
[0065]
By collecting the fiber mixture floating on the stored water 28 in the fiber collection tank 21, the fiber assembly according to the present invention is obtained.
[0066]
This fiber assembly may be used as it is, but usually it is used after removing the adhering tar content by solvent cleaning, heat cleaning, etc., and then heat-treating it in an inert atmosphere at 2000 ° C. or higher. . Further, the fiber length may be adjusted by pulverization or the like to facilitate mixing with the resin.
[0067]
The fiber assembly thus obtained can be suitably used as a filler for composite materials. That is, the composite material according to the present invention includes the base material and the fiber assembly according to the present invention.
[0068]
Examples of the base material include rubber, synthetic resin, metal, ceramics, and the like. When the synthetic resin, rubber and metal are mixed with the fiber assembly, it is preferable to improve the fluidity by heating the base material. For plastics with fluidity, higher viscosity plastics are more convenient for mixing with fiber assemblies than lower viscosity plastics. Suitable synthetic resins include nylon and polyetheretherketone. Since the rubber as a base material has a high viscosity and has viscoelasticity, it can be mixed well with the fiber assembly. The fact that mixing is easy when viscoelastic can be supported by the fact that the synthetic resin having rubber elasticity and the fiber assembly can be mixed well.
[0069]
When the base material is a metal, a melt forging method is employed for mixing the metal and the fiber assembly. In order to facilitate mixing of the metal and the fiber assembly, it is necessary to devise measures such as giving the metal an affinity for the fiber assembly or lowering the molten metal temperature. The metal as the base material is preferably an alloy in that such a device can be easily made.
[0070]
When the base material is ceramic, the ceramic slurry and the fiber assembly are mixed. When manufacturing a composite material using ceramics as a base material, when the composite material is manufactured by sintering at a high temperature, carbides and nitrides are preferable to oxides rather than oxides.
[0071]
A composite material containing carbon as a base material is mixed and cured with pitch, phenol resin, and the like, and then heated and carbonized in a non-oxidizing atmosphere. For the generation of voids during the carbonization treatment, a method such as reimpregnation with pitch and phenol resin is adopted as in the conventional carbon / carbon composite material production. Further, a so-called CVD (Chemical Vapor Deposition) or CVI (Chemical Vapor Infiltration) method in which a fiber assembly is preformed and carbon is chemically vapor-deposited on the fibers in the preform may be employed.
[0072]
The fiber assembly can be dispersed and mixed in the base material using a Henschel mixer, a two-roll, a three-roll, a twin-screw extruder, or the like depending on the kind of the base material.
[0073]
Various composite materials thus obtained are used as conductive materials, discharge materials and the like. In this composite material, the ultrafine vapor-grown carbon fibers are curled up and not dispersed in the base material. The dispersibility of the phase-grown carbon fiber in the base material is improved. Moreover, since the finely grown vapor-grown carbon fibers that are well dispersed and not rounded are in contact with each other, the composite material has various properties inherent to vapor-grown carbon fibers, such as electrical properties. Properties such as conductivity, thermal properties such as thermal conductivity, and mechanical properties such as strength, elongation, elastic modulus and the like can be satisfactorily exhibited.
[0074]
Therefore, the composite material according to the present invention is suitably used for conductive materials, discharge materials, and the like.
[0075]
【Example】
Hereinafter, an example explains.
Example 1
The apparatus used was the same shape as in FIG. The vertical reactor core tube (reaction tube) 2 is a silicon carbide cylinder having an inner diameter of 120 mm, an outer diameter of 130 mm, and a length of 2000 mm. The heating device 3 was an electric heater divided into 1 to 6 zones from the top, and the 1 zone was set to 800 ° C, the 2 zones were set to 900 ° C, and the 3 to 6 zones were set to 1180 ° C. Both the vaporizer 6 and the preheater 8 were controlled at 320 ° C., and the raw material gas supply nozzle was controlled at 350 ° C. The reaction tube and the supply system connected to the reaction tube are all purged with nitrogen after passing through a gas flow meter of 7, 10, 13 and then replaced with hydrogen, and a predetermined flow rate is applied. The guide gas supply chamber was supplied with predetermined nitrogen from the guide gas flow meter 15, nitrogen was supplied to the fiber collection tank 21 from the dilution gas introduction pipe 22, and the exhaust fan communication pipe 27 was connected to the activated exhaust fan. Further, water was supplied to the seal water tank 19, adjusted so as to flow stably from the seal water pipe 20, and water was sprayed from the water sprayer 23. This state was maintained for several minutes, and after confirming that the oxygen concentration at the outlet of the discharge pipe 18 and the fiber collection box 21 became 1% or less, the following combustible gas introduction work was started.
[0076]
The source gas supply nozzle is supplied with 4 L / min of methane, the second gas supply unit 11 is supplied with a mixed gas of methane 5 L / min and hydrogen 10 L / min, and the third gas supply unit 14 is supplied with 15 L / min of hydrogen. Nitrogen was supplied to the gas supply chamber at 40 L / min. The exhaust fan and the seal water tank head were controlled so that the micro differential pressure gauge installed in the third gas supply unit 14 and the guide gas supply chamber 16 showed a value lower than the outside air by about 2 to 5 mm.
[0077]
Here, as a catalyst source including a carbon source, a liquid of 15% by weight of ferrocene, 6% by weight of thiophene, and 79% by weight of benzene is supplied from the raw material liquid tank 4 by a raw material supply pump at a rate of 0.7 cc / min. The mixture was mixed with 4 L / min of methane and flowed through a reaction tube from a source gas supply nozzle to carry out the reaction. One hour later, the supply of the raw material liquid was stopped and the combustible gas was replaced with nitrogen. Then, the apparatus was released to the atmosphere, and the fibers in the fiber collection 21 were collected. After drying and tar removal, the weight was measured. The weight was about 80 g and the carbon yield was about 25%.
[0078]
This fiber was randomly observed by SEM. The average diameter of the fine fibers was 25 nm, the average diameter of the thick fibers was 80 nm, and the amount of the latter was about 5% by volume. Examples of SEM photographs are shown in Photos 1 to 6.
[0079]
(Comparative Example 1)
The apparatus conformed to Example 1. The vertical reactor core tube (reaction tube) 2 is a silicon carbide cylinder having an inner diameter of 90 mm, an outer diameter of 100 mm, and a length of 2000 mm. The heating device 3 was an electric heater divided into 1 to 6 zones from the top, and the 1 zone was set to 600 ° C, the 2 zones were set to 800 ° C, and the 3 to 6 zones were set to 1120 ° C. Both the vaporizer 6 and the preheater 8 were controlled at 320 ° C., and the raw material gas supply nozzle was controlled at 400 ° C. The reaction tube and the supply system connected to the reaction tube are all purged with nitrogen after passing through a gas flow meter of 7, 10, 13 and then replaced with hydrogen, and a predetermined flow rate is applied. The guide gas supply chamber was supplied with predetermined nitrogen from the guide gas flow meter 15, nitrogen was supplied to the fiber collection tank 21 from the dilution gas introduction pipe 22, and the exhaust fan communication pipe 27 was connected to the activated exhaust fan. Further, water was supplied to the seal water tank 19, adjusted so as to flow stably from the seal water pipe 20, and water was sprayed from the water sprayer 23. This state was maintained for several minutes, and after confirming that the oxygen concentration at the outlet of the discharge pipe 18 and the fiber collection box 21 became 1% or less, the following combustible gas introduction work was started.
[0080]
The source gas supply nozzle is supplied with 2.44 L / min of hydrogen, the second gas supplier 11 with 8 L / min of hydrogen, the third gas supplier 14 with 8 L / min of hydrogen, and the guide gas supply chamber with nitrogen. Was supplied at 16 L / min. The exhaust fan and the seal water tank head were controlled so that the micro differential pressure gauge installed in the third gas supply unit 14 and the guide gas supply chamber 16 showed a value lower than the outside air by about 5 mm.
[0081]
Here, the raw material liquid is supplied and vaporized from the raw material liquid tank 4 by a raw material supply pump, and 2.60 L / min of raw material gas (composition: ferrocene 0.12 mol%, thiophene 0.10 mol%, toluene 5.80). (Mole%, hydrogen 93.98 mol%) from the source gas supply nozzle to the reaction tube to carry out the reaction. After 6 hours, the supply of the raw material liquid was stopped, the combustible gas was replaced with nitrogen, the apparatus was opened to the atmosphere, the fibers in the fiber collection 21 were collected, the weight was measured after drying and tar removal. The weight was about 24 g and the carbon yield was about 12%.
[0082]
This fiber was randomly observed by SEM, and it was difficult to find a large diameter fiber having an average diameter of 20 nm and a diameter of 50 nm or more.
(Example 2)
Example 1 and Comparative Example 1 were repeated to obtain about 100 g of each sample. A graphitized vapor-grown carbon fiber (average diameter of about 0.1 μm) having a nominal diameter of about 0.1 μm and a graphitized product at 2500 ° C. after tar removal were prepared as samples for evaluation tests.
[0083]
Example 1 Nylon 66 resin pellet "NOVAMID3010SR" manufactured by Mitsubishi Kasei Co., Ltd. was mixed with 9 parts by weight of the sample / 91 parts by weight of the resin (kneading extrusion using LABOPLASTOMILL manufactured by Toyo Seiki Seisakusho Co., Ltd.), and a fiber mixed wire And cut with scissors into pellets.
[0084]
A test piece having a thickness of 4 mm, a width of 10 mm, and a length of 80 mm was obtained from the pellets using a tabletop injection molding machine “Handy Try” manufactured by Shinsei Servik.
[0085]
Test pieces were obtained in the same manner for the sample of Comparative Example 1 and a commercially available 0.1 μm product. The above three types of fibers all have a specific gravity of 2.2 and the resin has a specific gravity of 1.15. Therefore, all of these test pieces contained 5% by volume of vapor-grown carbon fiber (from the weight percentage). Conversion to volume percentage).
[0086]
Table 1 shows the results of the specific resistance measurement by the three-point bending test according to JIS-K7203 and the four-terminal method.
[0087]
[Table 1]

[0088]
【The invention's effect】
According to the present invention, there is little twisting and entanglement of the ultrafine vapor growth carbon fiber, the large vapor growth carbon fiber is dispersed in the ultrafine vapor growth carbon fiber, and the ultrafine vapor growth carbon fiber is in proper contact. A fiber assembly can be provided.
[0089]
According to the present invention, it is possible to provide a composite material in which the fiber aggregate is dispersed in a base material and electrical characteristics, mechanical characteristics, and thermal characteristics are improved.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a vapor growth carbon fiber production apparatus capable of producing a fiber assembly according to the present invention.
FIG. 2 is an SEM photograph of the fiber obtained in Example 1 as a drawing substitute photograph.
FIG. 3 is a SEM photograph of the fiber obtained in Example 1 as a drawing substitute photograph.
FIG. 4 is a SEM photograph of the fiber obtained in Example 1 as a drawing substitute photograph.
FIG. 5 is a SEM photograph of the fiber obtained in Example 1 as a drawing substitute photograph.
FIG. 6 is a SEM photograph of the fiber obtained in Example 1 as a drawing substitute photograph.
FIG. 7 is a SEM photograph of the fiber obtained in Example 1 as a drawing substitute photograph.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vapor growth carbon fiber manufacturing apparatus, 2 ... Vertical furnace core tube, 3 ... Heating apparatus, 4 ... Raw material liquid tank, 5 ... Raw material liquid supply pump, 6 ... Vaporizer, 7 ... 1st gas flow meter, 8 ... Preheater, 9 ... Raw material gas supply nozzle, 10 ... Second gas flow meter, 11 ... Second gas supply device, 12 ... Rectifier, 13 ... Third gas flow meter, 14 ... Third gas supply unit, 15 ... Guide gas Flow meter, 16 ... guide gas supply chamber, 17 ... rectifier, 18 ... discharge pipe, 19 ... sealed water tank, 20 ... sealed water pipe, 21 ... fiber collecting tank, 22 ... dilution gas introduction pipe, 23 ... water sprayer, 24 ... 1st partition plate, 25 ... 2nd partition plate, 26 ... Constant water level drainage hole, 27 ... Exhaust fan connecting pipe, 28 ... Reserved water, 29 ... Fiber (product).

Claims (4)

Containing an aggregate of small-diameter vapor-grown carbon fibers and an aggregate of large-diameter vapor-grown carbon fibers, the average diameter of the aggregate of small-diameter vapor-grown carbon fibers is 3 to 50 nm, The average diameter of the aggregate of vapor-grown carbon fibers is 60 to 300 nm,
The aggregate of large-diameter vapor-grown carbon fibers has a volume percentage of 0.1 to 30% of the total vapor-grown carbon fibers . The aggregate of the small-diameter vapor grown carbon fibers has an average aspect ratio of at least 30 and the aggregate of the large-diameter vapor-grown carbon fibers has an average aspect ratio of 2 to 100. 2. The fiber assembly according to claim 1, wherein an average aspect ratio of the aggregate of diameter vapor-grown carbon fibers does not exceed an average aspect ratio of the aggregate of small-diameter vapor-grown carbon fibers. The Both assemblies and the large径気-grown carbon fiber aggregate of the thin vapor-grown carbon fibers, according the to claim 1 or 2 which is graphitized fibers formed by heat treatment at 1,500 to 3,500 ° C. Fiber assembly. A composite material comprising the fiber assembly according to any one of claims 1 to 3 .

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