JPS63203870A - Acidic group-containing carbonaceous fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to acidic group-containing carbonaceous fibers.

More specifically, the present invention relates to ultrafine vapor-grown carbonaceous fibers containing acidic groups and nitrogen.

(Prior Art) Carbon fiber is used in various composite materials due to its excellent mechanical properties, and demand for it has been rapidly increasing in recent years. but,
Conventional carbon fibers are manufactured through complicated processes such as firing and carbonizing organic fibers, which has a cost limit. In contrast, a method has been attempted in which hydrocarbons are thermally decomposed and carbon fibers are produced on a substrate through a gas phase reaction.

Furthermore, the present inventors introduced hydrocarbons into a heating space together with a specific organic metal compound and a carrier gas, and created extremely thin, fine, and unique structures in a kind of floating state within the space rather than on the substrate. This method, which succeeded in synthesizing carbonaceous fibers having the following properties, is a simple and industrially valuable method.

(Problems to be solved by the invention) The carbonaceous fibers obtained here have a unique structure, are crystalline,
It has excellent orientation, and therefore has excellent mechanical properties, electrical properties, and suitability for electrode materials, and is expected to be put into practical use. However, due to this structural perfection,
It has poor adhesion and wettability with other materials such as resins and polar solvents such as water, which limits its use.

(Means for Solving the Problems) The present inventors have studied various methods for modifying the surface of the above-mentioned carbonaceous fibers. Due to the ultra-fine and fine fibers to be produced, we have investigated the reaction method, selection of conditions, reaction control devices, reaction treatment equipment, and the form of the carbonaceous fiber itself during reaction treatment. the result,
The present invention was achieved by successfully retaining acidic functional groups without damaging the fiber body.

That is, in the present invention, the acidic functional group is
f and 0.03 to 3% by weight of halogen, and the diameter is 0.
, 01 to 4 μm carbonaceous fiber.

In the present invention, the carbonaceous fiber has a diameter of 0.01 to 4 μm.
and preferably o, oi to 2 μm, especially 0.02 to 1
It is μm. There is no particular restriction on the length of the fibers, but when used as a reinforcing material, the longer the better, and the fiber length L
)/fiber diameter (D) is preferably 10 or more, particularly preferably 50 or more.

The carbonaceous fiber of the present invention is a fiber formed by a vapor growth method and has a unique shape consisting of a core and a carbon layer surrounding it that looks like an annual ring when observed with an electron microscope. , the carbon layer has the property of being easily converted into graphite or graphite. That is, the carbonaceous fiber as used in the present invention is a general term for carbonaceous fibers such as nine-carbon fibers formed by a vapor phase growth method and fibers similar to graphite obtained by heat-treating these fibers.

In addition, the carbonaceous fiber of the present invention has an acidic group content determined by a titration method of
The carbonaceous fiber 11 is in a range of 92 to 250 μeq, preferably 5 to 200 μeq, particularly 10 to 150 μeq. If the amount of acidic groups is less than 2 μsq, wetting with the resin, binder or water is insufficient;
If it exceeds μsq, the unique properties of the carbonaceous fiber cannot be fully exhibited. To quantify acidic groups by titration, sample 52 is weighed into an Erlenmeyer flask with a stopper, and
Accurately add aOH40- with a whole pipette, add an appropriate amount of water, leave to stand for 20 minutes with occasional shaking, and then immerse in an ultrasonic vibrator for 15 minutes. Transfer this solution to a Daruma flask, add water to make the volume accurate, then take out exactly the amount A with a whole pipette, and titrate with 1/) ON HC/.

For titration, use a potentiometric titrator to determine the amount of acidic groups from the titration curve.

In the present invention, halogens include fluorine, chlorine, bromine, and iodine, but chlorine or bromine is preferable, and it is easier to add these than fluorine or iodine, and to control the reaction described below for introducing acidic groups. It is easy and preferable. The amount of halogen is 0.03 to 3 times, and this halogen is not present in the carbonaceous FB and fiber generation stage, but is introduced during the post-reaction when acidic groups are introduced.
Therefore, it is thought that there is an interaction effect with the introduction of acidic groups, and the improvement of the wettability and adhesion of carbonaceous fibers, which is the objective of the present invention, can be achieved without introducing a large amount of acidic groups. For this reason, if the halogen content is 0.03% by weight or less, it is not preferable because a large amount of acidic groups must be introduced, whereas if the halogen content is increased, the carbonaceous fiber tends to deteriorate when introduced. Undesirable. Therefore, the content of halogen is preferably 0.05 to 2% by weight,
In particular, it is in the range of 0.08 to 1.2 weight.

In the present invention, the most preferable method for introducing acidic groups and halogens is to heat the raw material carbon fiber in the presence of an oxygen-containing compound and a halogen-containing compound, or to perform an excitation reaction using other methods. It is also preferable to heat the fibers or cause them to undergo an excitation reaction using other methods, and then to react with the oxygen-containing compound, and as an alternative method, it is also possible to use a method in which the reaction is carried out in the reverse order.

As the oxygen-containing compound, inorganic oxygen compounds such as oxygen, ozone, carbon oxide, carbon dioxide, and water, particularly oxygen, are preferable, and organic compounds such as methanol, acetone, formaldehyde, acetaldehyde, and acetic acid may also be used.

Examples of halogen-containing compounds include fluorine, chlorine, bromine, iodine, hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide, as well as chloric acid, bromic acid, bromine chloride, and methyl chloride, ethyl chloride, and tetrachloride. Organic halogen compounds such as carbon and methyl bromide may also be used, but inorganic halogen compounds are preferred, particularly ct, Br2t HCt+ HBr, and the like. In addition, Ar @ H is used as a diluent gas during this reaction.
A gas such as e + 12 can be used.

These oxygen-containing compounds and halogen-containing compounds are added to allotropic fibers at temperatures ranging from 350 to 1,200°C, particularly from 400 to 1,000°C.
In this method, when oxygen is used as the oxygen-containing compound, the oxygen concentration is lowered to 0.
HCt as 1-25 capacity.

C22, HBr or Br2 present (0,01-15
Capacity h) If the reaction is carried out with nitrogen gas, the reaction will be very mild, e.g. 400 to 1200°C, preferably 450°C.
It is preferable that the reaction can proceed at a temperature of ~1000°C.

Other reaction methods include special excitation treatment,
Examples of special excitation treatments include plasma treatment, electron beam irradiation treatment, radiation treatment such as X-rays and rills, and irradiation with ultraviolet rays and laser light. Among these, preferred methods include plasma treatment and electron beam irradiation treatment. is highly effective and preferable.

Among these, to give an example of plasma processing methods, it is convenient to mainly use inorganic gas as a carrier and use plasma generated by low frequency discharge, high frequency discharge, microwave discharge, DC glow discharge, corona discharge, etc. This is done by exposing carbonaceous fibers to this plasma state.

Here, examples of the inorganic gas include Ar and He.

NHs, N, , N2 oxygen-containing compounds 0□,
Various gases such as Cow and COz can be used, and mixtures of these gases can also be used. Preferred carrier gases include Hrt He, N2e a2. o, especially Ar+
N2Io or a mixed gas thereof is used, and an oxygen-containing compound and a halogen-containing compound are mixed in these carrier gases.

The gas pressure when generating plasma is 0.001T
orr #l atmospheric pressure, special KO, 1 m 100 Torr, and the plasma treatment time varies depending on the gas type, the capacity of the plasma generation power source, the shape and form of the carbon fiber to be treated, etc., but generally it is 0.01 seconds to 20 minutes. , preferably 0.1 sheets/~lO minutes, especially 0.5 seconds~5 minutes,
If the time is shorter than this, the surface modification effect will appear. On the other hand, if it exceeds this range, unfavorable conditions such as noticeable surface etching of carbon fibers will occur. Oxygen-containing compounds and halogen-containing compounds The carbonaceous fiber of the present invention obtained by reacting as in
It can be put to practical use by attaching a tasing material or an auxiliary material for surface improvement.

For example, when used for composite reinforcement with resin, rubber, etc.
Epoxy resins, phenolic resins, unsaturated ester resins, amide resins, silicone resins, rubber latex, or mixtures thereof can be preferably used.

(Example) The present invention will be explained below using examples.

Example 1 Vapor-grown carbonaceous fiber with a diameter of 0.08 to 0.3 μm (
Trisacetylacetonate iron and benzene at 1400℃
It was introduced into the heating space of 2000 and synthesized in a floating state. ) was compressed using a press, and this was packed into a reaction tube of a tubular electric furnace, and the air in the reaction tube was replaced with nitrogen. Next, the electric furnace was heated to 1,700° C., and then nitrogen gas containing 3.0 volumes of oxygen and 11.0 volumes of lIC was flowed to react for 8 minutes. After cooling, the amount of acidic groups and the amount of halogen in the obtained carbonaceous fiber were measured, and the results were 88 μeq/y and 0.6% by weight, respectively.0 This fiber is easy to soak in water, and it is difficult to combine with epoxy resin. A good reinforcing effect was clearly observed by the molding, for example, the bending strength was improved.

Comparative Example 1 The raw carbon fiber used in Example 1 had an acidic group of 0.5 μe.
Below q/f, halogen was 0. Even when this fiber is soaked in water, it does not get wet and floats up. Moreover, the strength of the molded product of the composite molded product with the epoxy resin was not improved at all.

Example 2 The same experiment as in Example 1 was conducted using graphite carbonaceous fibers obtained by heat-treating the raw carbon fibers of Example 1 at 2500° C. for 20 minutes. At this time, the oxygen concentration was set to 2.5 volumes, and the heating temperature was also set to 650°C. The amount of acidic groups in the obtained carbonaceous fibers was 25 μeq/r, and the amount of halogen was 0.6% by weight.

Example 3 An experiment similar to Example 1 was carried out using an oxygen concentration of 1.7 volume and 11c.
t1.2 Volume fjk %, reaction temperature 'r s o o
The reaction time was 5 minutes at 0.degree. C. to obtain carbonaceous fibers having acidic groups of 72 .mu.eq/gs and a halogen content of 0.7 wt.%.

Example 4 Vapor-grown carbonaceous fibers (synthesized in a floating state) with a diameter of 0.1 to 0.5 μm were compressed using a press, and this was placed in a high-frequency plasma (13,56■b) device. -”To
After exhausting to below rr, argon gas containing 5 volumes of oxygen and 1 volume of chlorine was flowed to adjust the pressure to 0.1 Torr. A high frequency power source was oscillated at an output of 200 W to generate plasma, and plasma treatment was performed for 8 minutes. After stopping the plasma, it was taken out into the atmosphere and left for 1 hour, and then the amount of acidic groups and the amount of halogen were measured, and they were 65μeq/g and 0.9% by weight, respectively.
I got it.

Example 5 The carbonaceous fibers used in Example 4 were placed in a polyethylene bag, and the gas inside the bag was replaced with argon gas containing 1 liter of oxygen, 1 tts of chlorine, 2 volumes of chlorine, and then irradiated with an electron beam of 20 Mrad. Then, the bag was opened and taken out into the atmosphere. 1
After standing for a period of time, the amounts of acidic functional groups and nologen were measured and the results were 21 μeq/g and 0.8% by weight, respectively.

(Effect of ignition) Since the carbonaceous fiber of the present invention contains a moderate amount of acidic functional groups and 710 gene, it has good adhesion and wettability with rubber and resin. It is easy to compose and mix, and when used as a composite material, the mechanical properties are favorably improved. Therefore, it is extremely useful as a reinforcing material for resins, rubber, etc. It is also effective as a functional fiber that can adsorb various compounds.

Claims (1)

[Claims] 2-250μeq/g of acidic groups and 0.03 halogens
~3% by weight carbonaceous fibers with a diameter of 0.01~4μm