JPS61225326A - Carbonaceous fiber having acidic group - Google Patents

Abstract

PURPOSE:To provide the titled fiber having a diameter and a length/diameter ratio of falling within specific respective ranges and containing an acidic group having specific shape, terminal carboxyl group concentration and oxygen concentration, and exhibiting excellent adhesivity to the matrix resin of a composite material. CONSTITUTION:The objective fiber has a diameter of 0.01-4mum, preferably 0.07-2.5mum and a length/diameter ratio of >=20, preferably >=100 and is composed of graphite layers or carbon layers convertible easily to graphite and arranged concentrically parallel to the fiber axis. The terminal carboxyl group concentration is 0.1-500mu.mol/g. preferably 1-50mu.mol/g by titration and the oxygen concentration O1S/C1S is >=0.05, preferably >=0.1 by X-ray spectrometry. The fiber can be produced by introducing an acidic functional group to a fiber obtained by a vapor-phase process, especially a fluidized catalyst process, if necessary, after heat-treatment.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to carbonaceous fibers having acidic groups, and more particularly to carbonaceous fibers that stably retain acidic groups and are produced by a gas phase method, particularly by a floating method. It is.

(Prior Art) Carbon fiber is a raw material that has been rapidly growing in recent years as a variety of composite materials due to its excellent mechanical properties. Conventionally, carbon fibers were manufactured by methods such as sintering and carbonizing organic fibers, but recently carbon fibers have been manufactured using a gas phase method that generates carbon fibers through thermal decomposition of hydrocarbons and catalytic reactions. Attempts have been made (for example, industrial materials,
July issue, 109 pages, consecutive wins, Koyama and JP-A-1983-
180615).

Carbon fibers obtained by the vapor phase method have superior crystallinity, orientation, and high strength compared to conventional ones, and nonwoven fabrics, laminates, etc. obtained from these fibers have excellent electrical conductivity. Because of this, it is expected to be used in battery electrode materials, heating elements, etc., and it is also being used in filters, catalyst carriers, etc. by taking advantage of its heat resistance and chemical resistance.

(Problems to be Solved by the Invention) However, in the conventional gas-phase method, carbon fibers are grown on a substrate, or carbon fibers are grown using ultrafine metal powder sprinkled on a substrate. However, the obtained fiber diameter is relatively large, and when used in a composite material with a resin, the adhesiveness with the resin is poor, which poses a practical problem.

Furthermore, since conventional carbonaceous fibers generally have poor wettability, adhesion to resins becomes an important problem. For this reason, methods for surface modification of various existing carbon fibers are being researched, such as chemical reactions in the liquid phase or gas phase, or plasma treatment, but all of them are highly reactive acidic. It could not be said that the group was stably retained, and sufficient adhesiveness could not be obtained.

The present inventors introduced hydrocarbons and a specific organometallic compound into a heating zone together with a carrier gas, and thermally decomposed the hydrocarbons to cause a catalytic reaction. They discovered that the compound could be synthesized and filed a patent application (Japanese Patent Application No. 59-83495, Japanese Patent Application No. 59-231967, 59-253550, etc.).

(Means for Solving the Problems) The present inventors investigated various chemical reactivities of the above-mentioned carbonaceous fibers, and found that this fiber is extremely reactive, and in particular, stabilizes acidic functional groups. The present invention has been achieved based on the discovery that the above properties can be possessed.

The carbonaceous fiber of the present invention has a fiber diameter of 0.01 to 4 μm.
, fiber length/fiber diameter is 20 or more, carboxyl terminal group amount by titration method is 0.1 to 500 μ m o f /
g % Oxygen concentration by X-ray spectroscopy (ESCA) 01
s/C1s is 0.05 or more, it is characterized by having acidic groups in which layers of graphite or carbon that can be easily converted to graphite are arranged in a tree ring shape parallel to the longitudinal axis.

The diameter of the carbonaceous fiber of the present invention is 0.01 to 4 μm, preferably 0.05 to 3 μm (especially 0.07 to 2.5.crm).
). If the diameter of the fibers is larger than this, the degree of entanglement of the fibers will be reduced, making it impossible to obtain desirable properties. In addition, the fiber length L)/fiber diameter (D) is 20 or more, preferably 5
It is 0 or more (especially 100 or more). If L/D is less than 20, sufficient entanglement cannot be obtained when the fibers are aggregated, resulting in poor properties.

The carbonaceous fiber of the present invention may have any shape, such as linear, curved, or crimped, but preferably has a crimp number of 1 or more and a crimp degree of 0.5 to 50% (preferably 5 to 50%). It has crimps. The number of crimps in this case refers to the total number of peaks and troughs of bending in a fiber length of 20 μm using a scanning electron microscope observation photograph, and the degree of crimps refers to the total number of bending peaks and troughs in a fiber length of 20 μm. 40μ in distance
m, the actual fiber lengths a and b between them were measured using a planimeter, and calculated using the following formula (average value of 5 random measurements).

ab

When the carbonaceous fiber of the present invention was observed with an electron microscope, it was found that the carbon fiber was formed by morphologically forming layers of graphite or carbon that could be easily converted into graphite, arranged in a growth ring shape parallel to the longitudinal axis. . The carbonaceous fibers of the present invention collectively refer to carbon fibers and graphitized fibers.

Further, the carbonaceous fiber of the present invention has a carboxyl terminal group content of 0.01 to 500μ·m o It 7g1 by titration method.
Preferably 0.5 to 200 (especially 1 to 50) μ・m o
l/g. The amount of carboxyl terminal groups determined by this titration method is determined by the following method. That is, 5g of the sample was weighed into a 500mf stoppered Erlenmeyer flask, and 10Q of water was added.
mt! Accurately add 40 ml of X115ONaOH using a whole pipette, add 60 ml of water, and turn it to 200 ml.
Close it, let it stand for 20 minutes with occasional shaking, then soak it in an ultrasonic vibrator for 15 minutes, collect the dissolved WE, 50 m It, into a Daruma flask with a whole pipette, and add it to a HCff of 115 ON.
Titrate with i. For titration, the amount of functional groups is determined from the titration curve using a Metrohm potentiometric titrator.

If the amount of carboxyl terminal groups does not reach 0.1, sufficient adhesion cannot be obtained when mixed with a resin, binder, etc., and if it exceeds 500μ・mol/g, the carbonaceous fiber has a unique property. It is not preferable because the properties deteriorate.

The oxygen concentration of the carbonaceous fiber of the present invention measured by X-ray photoelectron spectroscopy (ESCA), that is, the relative integrated intensity of 01s to C1s (Of S/Cl5) is 0.05 or more, preferably 0.07 or more, and more preferably 0. .1 or more.

In this case, the relative integrated intensity (01s/C1s) is determined by using an X-ray photoelectron spectrometer and using an excitation X-ray as An! to α14
It was measured using B6.6 eV, X-ray output of 10 kV, 20 mA, temperature of 40° C., and vacuum degree of IQ torr. From the obtained spectrum, the relative integrated intensity of 01s to C1s was calculated and used as an index of the amount of oxygen-containing functional groups on the carbon fiber surface. If this value is less than 0.05, the acidic groups will not be sufficient and the adhesiveness with resin etc. will decrease.

Further, the fiber of the present invention exhibits a sharp band peak with a half value of the C1s band in ESCA of 1.6 or less, particularly 1.5 or less, and has a homogeneous structure.

The carbonaceous fiber of the present invention can be produced by introducing a mixed solution of hydrocarbons and a specific organometallic compound into a heating zone together with a carrier gas as needed, causing the hydrocarbons to thermally decompose and undergo a catalytic reaction. It is produced by introducing an acidic functional group after heat treatment if necessary.

The above-mentioned hydrocarbons are not particularly limited, and include hydrocarbons that are solid at room temperature including anthracene, naphthalene, etc., and room temperature hydrocarbons including benzene, toluene 1, xylene, styrene, hexane, isooctanecyclohexane, cyclopentadiene, etc. It may be a liquid hydrocarbon or a gaseous hydrocarbon including methane, ethane, propane, butane, ethylene, propylene, butylene, butadiene, acetylene, and the like.

Examples of organometallic compounds used in the present invention include Group 1 Va (especially 7t, Zr), Group Va (especially V), Group Vla (especially (:, r, Mo, W), and group (especially Mn), group (especially Fe, Co, Ni5Ru, R
h, Pd, Os, Ir, Pt), especially cyclopentadienyl metal compounds, carbonyl metal compounds, benzene-metal compounds, alkyl, allyl or alkynyl metal compounds, β-diketone metal complexes, Keto acid ester metal complexes, metal carboxylates, especially iron such as bis(cyclopentadienyl) iron, cyclopentadienyl compounds such as nickel or cobalt, iron carbonyl, nickel carbonyl, cobalt carbonyl, cyclopenta carbonyl compounds such as iron, nickel or cobalt, such as carbonyl carbonyl iron, β-diketone metal complexes such as iron, nickel or cobalt, such as iron complexes of di- or triacetylacetone;
Iron, nickel or cobalt complexes such as iron complexes of di- or triacetoacetic esters, fumarates of iron, nickel or cobalt such as iron fumarate, iron naphthenate, carboxylates of higher hydrocarbons, or derivatives thereof, etc. gives good results.

The method for supplying the organometallic compound is to directly heat it and supply it in a gaseous state to the reaction system, or to dissolve or finely disperse the organometallic compound in a hydrocarbon liquid and then heat it to cause the reaction. Methods such as supplying it to the system or blowing it out are used.

Supply amount of the above organometallic compound (supply weight % per light per minute)
) is 0.01% by weight or more based on the mixture with hydrocarbon,
The content is preferably 0.05% by weight or more, particularly 0.2% or more. If the amount of the organometallic compound is too small, fibrous materials tend to be difficult to form and granular materials tend to increase.

The temperature range for introducing hydrocarbons and organometallic compounds is 150
A suitable temperature is 0°C or lower, preferably 100 to 1300°C, particularly preferably 100 to 500°C. If the temperature at the introduction position is too low, it will be difficult for the raw material to maintain a gaseous state;
It is also undesirable for activating organometallic compounds.

Furthermore, if the temperature exceeds 1500°C, carbonization occurs, which increases the production of particulate matter, which tends to cause clogging and reduce the fiber yield. The reaction heating temperature range is preferably 500 to 1800°C, particularly 800 to 1500°C. If the temperature of the reaction part is outside the above range, particulate matter is likely to be generated.

In the present invention, in order to introduce acidic functional groups into carbonaceous fibers, known methods such as gas phase oxidation method, electrolyte solution phase oxidation method,
An oxidizing agent liquid phase oxidation method, a plasma treatment method, etc. can be used. For example, in a gas phase oxidation method using air, oxygen, ozone, etc., when ozone is used, the ozone concentration is 0.
．． 1 to 5% by weight, and the treatment temperature is preferably 30 to 300°C. Moreover, when air is used, it is desirable to carry out in heated air usually at 350 to 800°C. Further, if necessary, oxygen diluted with an inert gas may be mixed into the air to adjust the oxygen concentration. When using the electrolyte phase oxidation method,
This is carried out by using a carbonaceous fiber as an anode and applying a voltage between it and a cathode plate in an electrolytic solution. In addition, when using an oxidizing agent liquid phase oxidation method, for example, an oxidizing agent such as nitric acid, hypochlorous acid, chromate, dichromate, chromic anhydride, permanganate, etc. is dissolved in water or an organic solvent, and the necessary The carbonaceous fibers may be treated with a material heated accordingly. In addition, the plasma treatment method uses, for example, an internal electrode-type low-temperature plasma generator having a counter-discharge electrode to generate a glow while flowing a gas containing oxygen, oxygen and carbon monoxide, carbon dioxide, and, if necessary, a gas containing organic matter under reduced pressure. All you have to do is discharge. In this case, the oxygen concentration in the gas is preferably 10% by weight or more.

Further, acidic functional groups can also be introduced by plasma treatment with an inert gas such as helium, neon, argon, or nitrogen, followed by contact with an unsaturated carboxylic acid. The atmospheric pressure inside the plasma device is, for example, 0.001~
The range of 10 t o r r is preferable, and under such gas pressure, the frequency of 10 KHz to 1
By applying power of 10 W to 100 KW at a high frequency of 0 MHz, stable glow discharge can be performed. Note that as the discharge frequency band, in addition to the above-mentioned high frequency, low frequency, microwave, direct current, etc. can be used. Since the carbonaceous fiber used as a raw material has high reactivity, introduction of such acidic functional groups can be carried out under mild conditions without weight loss.
A large amount of acidic functional groups (eg, carboxyl groups, phenolic hydroxyl groups, etc.) can be introduced.

(Effects of the Invention) The carbonaceous fibers having acidic groups of the present invention have a large amount of acidic functional groups without deteriorating the properties of the carbonaceous fibers themselves, so they can be used as base materials when used in composite materials. It has excellent adhesion with resins (especially reactivity with epoxy resins, etc.), such as O
Fibers for composite materials such as antistatic parts such as A equipment, fields that require electrical conductivity such as electrode materials, parts that generate high heat (automobile engine related), parts that require thermal conductivity, etc. It is effectively used as a.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example 1) Using the apparatus shown in FIG. 1, carbonaceous fibers having acidic groups of the present invention were manufactured. This device includes a nozzle (for example, a two-fluid nozzle) 3 that spouts out a raw material liquid 11 mixed with a catalyst using a carrier gas (hydrogen and argon) 9, and a heater 5.
and a reaction tower (reaction section) provided with cooling nozzles 15 in sequence.
7, and a recovery section (bar filter 17) that communicates with the lower part of the reaction tower 7 via a communication section 21. In the figure, 13 is a cooling gas (for example, nitrogen gas), and 19 is a cooling gas (for example, nitrogen gas). Exhaust gas is shown. Using the above-mentioned apparatus in which the volume of the reaction tower 7 is 4011, styrene and pentacarbonyl iron are added as raw materials.
．． A mixed solution containing 5% by weight of iron and 0.1% by weight of iron bisacetylacetonate was mixed with 50% by volume of hydrogen and 50% by volume of argon.
from the nozzle 3 to the reaction tower 7 using a mixed gas of
I squirted inside.

The temperature near the heating section in the tower was set at 1050° C., and the spray condition was adjusted so that the sprayed raw material did not collide directly with the heater 5. Nitrogen gas is ejected as a cooling gas from the nozzle 15 at the bottom of the reaction tower 7 to cool the produced carbon fibers and pass through the communication section 21 to the bag filter 17.
The generated carbon fibers were collected. Raw material styrene: 4 g/min, mixed gas of hydrogen and argon: 0.511/min, cooling gas l/min
When reacted for 30 minutes at Min.
The (002) plane spacing 002 by X-ray diffraction is 3.52 people, the crystal size LC (002) in the C-axis direction is 35 people, and the half-width of C1s by X-ray photoelectron spectroscopy (ES CA) is 1.44. Carbonaceous fibers were obtained.

This carbon fiber was treated with 68% concentrated nitric acid for a predetermined time. The processing conditions are as shown in Table 1. The treated carbon fibers were washed with ion-exchanged water for about 1 hour, and then
The treated product was dried in an oven at ℃ for 30 minutes and evaluated. Oxygen concentration (0
The method for measuring the amount of carboxyl end groups by titration (1S/CIS) and titration is as described above.

(Comparative Example 1) An alumina furnace core tube (inner diameter 10 cm, length 10 cm) was placed in an electric furnace.
A 100cI is installed horizontally, and ultrafine Fe powder (3
A graphite manufacturing board sprayed with 0.000 g) was set. The substrate is 5 cm wide, 30 cm long, and 0.5 cffi thick, and the ultrafine powder is dispersed by suspending it in methyl alcohol.
This was done by spraying. The scattering was carried out evenly over the substrate, and the amount of ultrafine powder dispersed was about IMg. A gas inlet pipe was connected to one end of the furnace core tube, and a discharge pipe was connected to the other end, and hydrogen gas containing 100 ml of benzene vapor was flowed through the gas inlet pipe at a rate of 1000 cc per minute (at room temperature). and set the temperature to 1000℃
and held at that temperature for 180 minutes. The temperature was then raised to 1200°C and held at that temperature for 60 minutes.

Thereafter, the gas was changed to nitrogen, the temperature was cooled, and the substrate was taken out. The produced carbon fibers were taken out from the substrate and weighed. As a result, carbon fiber with a fiber diameter of 10 μm was 0.033 g/crA
-hr obtained.

The diameter of carbon fiber is 10 μm, doo2 is 3.52 people, E
The half value of C1s in SCA was 1.72. The fibers were treated with 68% concentrated nitric acid as shown in Table 1.

(Comparative Example 2) Ammonia was blown into a copolymer of 99.5 mol% acrylonitrile (AN) and 0.5 mol% itaconic acid with an intrinsic viscosity (η) of 1.80, and hydrogen at the carboxyl group terminal of the copolymer was added. was substituted with an ammonium group to prepare a modified polymer, and a solution of the modified polymer in dimethyl sulfoxide (DMSo) having a concentration of 20% by weight was prepared. This solution was filtered using a sintered metal filter with a mesh opening of 5 μm as a furnace material, the temperature was adjusted to 60° C., and the solution was discharged into a DMSO aqueous solution having a concentration of 50% at 60° C. As a base,
A material with a hole diameter of 0.05 mm and 4,500 holes was used, and the solidification and withdrawal speed was 18 m/min. After washing the coagulated thread with water,
After stretching 4 times in hot water, processing with silicone oil, drying and densification by contacting with a roller surface heated to 130 to 160°C, and then stretching in pressurized steam at 40 kg/a11 for 3 A fiber bundle with a single filament fineness of 0.7d and a total denier of 3150D was obtained by drawing it twice (Japanese Patent Application Laid-Open No. 57-117
No. 622).

The (002) plane distance d 002 of carbon fiber was 3.68 people, and the half value of C1s in ESCA was 1.85. The fibers were treated with concentrated nitric acid as shown in Table 1.

In order to compare the ease with which acidic functional groups can be introduced into the carbon fibers obtained in Example 1 and Comparative Examples 1 and 2, the carbon fibers were treated with 68% concentrated nitric acid for a predetermined period of time. The processing conditions are as shown in Table 1. The treated carbon fibers were washed with ion-exchanged water for about 1 hour, then dried in an open air at 120° C. for 30 minutes, and the treated products were evaluated. Oxygen concentration (Cs/Cs) determined by X-ray electron spectroscopy (ESCA)
Using an X-ray photoelectron spectrometer, ARK was used as the excited X-ray.
Using α1486.6eV, X-ray output 10kV, 2Qm
A: Measured at a temperature of 40° C. and a vacuum of IQ torr. The relative integrated intensity of O3 with respect to Cs was calculated from the obtained spectrum and used as an index of the amount of oxygen-containing functional groups on the carbon fiber surface.

Furthermore, the amount of carboxyl terminal groups determined by titration is a value determined by the following method. In other words, about 5 g of sample was heated to 300 m j!
Weigh into a stoppered Erlenmeyer flask and add 5 Q m of water 12.11
Accurately add 20mj+ of 5ONaOH whole-bichet, add 30mj+ of water to make 100mA, leave it for 20 minutes while shaking occasionally, and then soak it in an ultrasonic vibrator for 15 minutes.
50 mA of the solution was collected into a Daruma flask using a whole pipette, and the reactivity of the carbon fiber into which the acidic group had been introduced and the epoxy resin was tested. That is, 1 of epoxy resin (bisphenol A type) DER661 (manufactured by Dow Chemical Company)
500 mjl of 0% (weight) xylene solution! was heated to 150° C., and 5 g of the carbonaceous fibers treated with concentrated nitric acid were immersed therein. After treatment for 1 hour, the fibers were separated in a furnace, unreacted epoxy resin was washed with acetone, and then dried under reduced pressure. The weight of the obtained fibers was accurately weighed, the weight increase (per unit of 100 weight) was determined, and the amount of epoxy resin bonded to the carbonaceous fibers was measured. The results are shown in Table 2.

Table 2 Examples 2 to 5 Carbon fibers were produced under the same conditions as in Example 1 except that the organometallic compounds, raw material hydrocarbons, carrier gas, and cooling gas shown in Table 2 were used. Table 3 shows the physical properties of the obtained carbon fiber.

Margin Table 3 Below: The fibers obtained in Example 4 above were subjected to the same concentrated nitric acid treatment as in Example 1. Os/C of the obtained fiber
s is 1.85, acidic group by titration is 45 μmol/g
Met.

The fibers of Example 5 were treated in air at 450° C. for 1 minute. The Os/Cs of the obtained fiber was 0.63,
The amount of acidic groups determined by titration was 5.2 μm o 1 /g.

The fibers of Example 2 were treated with concentrated nitric acid at 120° C. for 10 minutes. Os/C8 of the obtained fiber is 0.54
The amount of acidic groups determined by titration was 4.9 μmol/g.

The fibers of Example 3 were treated with concentrated nitric acid at 120° C. for 20 minutes. The acidic group by titration is 95 μm o l
/g.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of an apparatus used for producing carbonaceous fibers of the present invention. DESCRIPTION OF SYMBOLS 1... Apparatus body, 3... Nozzle, 5... Heater, 7... Reaction tower (reaction part), 9... Carrier gas,
11... Raw material liquid, 13... Cooling gas, 15...
Cooling gas nozzle, 17... Bag filter (recovery section), 19... Exhaust gas, 21... Communication section. Agent Patent Attorney Takeshi Kawakita 2: Nozzle 5: Heater 7: Reaction part 9: Gas (hydrogen) 11: Reaction liquid 19: Exhaust gas 2F communication part

Claims (1)

[Claims] (1) The fiber diameter is 0.01 to 4 μm, the fiber length/fiber diameter is 20 or more, the amount of carboxyl end groups is 0.1 to 500 μmol/g by titration method, and X-ray optical spectroscopy (ESC)
A carbonaceous fiber having an acidic group in which the oxygen concentration O_1s/C_1s according to A) is 0.05 or more and is formed by arranging graphite or carbon layers that are easily converted into graphite in the form of growth rings parallel to the longitudinal axis. (1) The carbonaceous fiber having an acidic group according to claim (1), characterized in that the carbonaceous fiber has a crimp number of 1 or more and a crimp degree of 0.5 to 50%.