JPS63196772A - 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 carbonaceous fibers containing acidic groups.

More specifically, the present invention relates to ultrafine vapor-grown carbonaceous fibers having acidic groups added thereto by addition of organic polymerizable monomers.

(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 have been produced through complicated processes such as firing and carbonizing organic fibers, and have been limited in terms of cost. 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,
We succeeded in synthesizing extremely thin and fine carbon fibers with a unique structure, not on a substrate but in space, in a floating lump state. This method is simple and industrially valuable.

(Problem to be solved by the invention) The carbonaceous fiber obtained by this method has a unique structure, is 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, because of 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 investigated various methods for modifying the surface of the above-mentioned carbonaceous fibers. Since carbonaceous fibers are extremely thin and fine, we have investigated the reaction method, selection of conditions, reaction control devices, reaction treatment equipment, and the formability 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.

In other words, the present invention has an acidic functional group of 3 to 800 μeq/ and a diameter of 0 by adding an organic polymerizable monomer.
．． It is a carbonaceous fiber of 01 to 4 μm.

In the present invention, the carbonaceous fiber has a diameter of 0.01 to 4μ.
m, preferably 0.01 to 2 μm, especially 0.05 to 2 μm
It is 1 μm. There is no I\iVc limit on the fiber length, but
When used as a reinforcing material, the longer the fiber is, the more preferable it is, and the fiber length (L)/fiber diameter (D) is preferably 10 or more, particularly 50 or more.

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

Further, the amount of acidic functional groups in the carbonaceous fiber of the present invention determined by titration is in the range of 3 to 800 μeq, preferably 5 to 250 μeq, particularly 8 to 150 μeq per 11 of the carbonaceous fibers. If the amount of acidic functional groups is less than 3 .mu.sq, wettability with resin, nocedar or water will not be sufficient, while if it is more than 800 .mu.sq, the carbonaceous fiber will not be able to fully exhibit its specific properties. To quantify acidic functional groups by titration, approximately 52 samples are weighed into an Erlenmeyer flask with a stopper, and 17
Accurately add 5ON or 1/ION NmOH40d with a whole pipette, add an appropriate amount of water, and leave it for 20 minutes with occasional shaking, 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 exactly 1/4 volume with a whole pipette,
Titrate with 5ON or 1/ION) IoIl. For titration, a potentiometric titrator is used to determine the amount of functional groups from the titration curve.

In the present invention, when adding an organic polymerizable monomer to the carbonaceous fiber of the present invention, the acidic functional group is a monomer having an acidic functional group in all or part of the organic polymerizable monomer. It is especially added to carbonaceous fibers.

In the organic polymerizable monomer in the present invention, monomers having an acidic functional group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride, endomethylenetetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, and endomethylenetetrahydrophthalic acid. A typical example is a compound having an unsaturated group and a carzexyl group such as talic anhydride, and acrylic acid is particularly preferred. Furthermore, among the organic polymerizable monomers of the present invention, various compounds having an unsaturated group can be used as monomers other than the above-mentioned monomer having an acidic functional group. For example, preferred monomers include , styrene, acrylic ester, acrylic amide, methacrylic ester, methacrylic amide, vinyl chloride, vinylidene heptadide, vinyl acetate, butadiene,
Examples include isoprene, chloroprene, cyclointadiene, acrylonitrile, and vinylpyridine. Particularly preferred monomers include styrene, acrylic acid compounds, and diene compounds.

Examples of methods for adding these organic polymerizable monomers to carbonaceous fibers include plasma treatment of carbonaceous fibers in the presence or absence of organic polymerizable monomers, electron beam or X-ray treatment, etc. , a method of irradiating with radiation such as gamma rays, a method of irradiating with ultraviolet rays or laser light, etc., followed by a method of carrying out a contact reaction with an organic polymerizable monomer after performing these treatments. . In particular, among the above excitation treatment methods, plasma treatment methods and electron beam irradiation methods are highly effective and are preferred.

Among these, Hikora gives an example of a plasma processing method, which mainly uses inorganic gas as a carrier and uses plasma generated by low frequency discharge, high frequency discharge, microwave discharge, DC glow discharge, corona discharge, etc. This is conveniently carried out by exposing the carbonaceous fiber to this plasma state.

Here, examples of the inorganic gas include Ar, He,
N2.

Various gases such as Hz*Ox*NHs and Co*OO can be used, and a mixed gas of these gases can also be used. Preferred gases include Ar, Nl+01.
NH@I￥f, At*Nls 01, or a mixture thereof.

The gas pressure when generating plasma is 0.001T
o r r ~ 1 atm, especially 0.1 to 1 OOTorr. The plasma treatment time varies depending on the gas cylinder, the capacity of the plasma generation power source, the shape and form of the carbonaceous fiber to be treated, etc., but is generally 0. 01 seconds to 20 minutes, preferably 1 second to 10 minutes, especially 0.5 seconds to 5 minutes; on the other hand, shorter times will not produce the effect of reactivity with the organic polymerizable monomer. , above this range, undesirable conditions such as noticeable surface etching of the carbonaceous fibers occur.

After such an excitation treatment method such as plasma treatment or electron beam irradiation, the organic polymerizable monomer is brought into contact reaction with the organic polymerizable monomer in a gaseous, liquid, solution, or emulsion state. Contact and react in a covered state. The conditions for reacting the organic polymerizable monomer include a temperature range of 0°C to 250°C or room temperature to 200°C, and a reaction time of about 1 second to 2 hours, preferably several seconds to 1 hour. It is also preferable to remove oxygen from the reaction system during the reaction. Under such conditions, the organic polymerizable monomer is added to the carbonaceous fiber, and the amount added is generally 0.01 inch to a
, 1 t , preferably 0.1 to so++v, and the amount of addition and the amount of acidic functional groups mentioned above are adjusted depending on the application.

After being added in this way, it can be used for practical purposes by washing and drying as necessary, or by attaching sizing materials and surface treatment auxiliary materials. For example, resin! When used for composite reinforcement with rubber or the like, polyurethane 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 with reference to Examples.

Example 1 Vapor-grown carbon fibers with a diameter of 0.1 to 0.8 μm (trisacetylacetonate iron and benzene were introduced into a heating space at 1400°C and synthesized in a floating state) were compressed using a press,
This was installed in a high-frequency plasma (13.56 MHz) device, and after exhausting to 10-2 Torr, the pressure was adjusted to 0.1 Torr by flowing argon gas. 200 high frequency power supplies
It oscillated with an output of W to generate plasma, and plasma treatment was performed for 3 minutes. After stopping the plasma, acrylamide 1
Plasma-treated carbon fibers were immersed in an aqueous solution of 5% by weight and 5% by weight of acrylic acid, reacted at 80°C for 30 minutes, washed and dried, and the acidic functional groups of the resulting carbonaceous fibers were measured. It turned out to be 120μsq/? Met. This fiber wets well when immersed in water. Furthermore, when mixed with epoxy resin and molded, a remarkable reinforcing effect was observed, for example, an improvement in bending strength was observed.

Comparative Example 1 When the acidic functional groups of the vapor grown carbonaceous fiber of Example 1 were measured, it was found to be 0.5 μeq/? It was below. Even when this fiber is soaked in water, it does not get wet and floats up.

Furthermore, even when epoxy resin was mixed and molded, the strength of the molded product did not improve.

Example 2 An experiment similar to Example 1 was conducted using graphitic carbonaceous fibers obtained by heat-treating the vapor-grown carbonaceous fibers of Example 1 at 2500° C. for 20 minutes. At this time, 15% by weight of acrylamide
acrylic acid to 7% by weight.

The amount of acidic functional groups in the obtained carbonaceous fiber was 54 μeq/l.

Example 3 An experiment similar to Example 1 was conducted using vapor grown carbon fibers (synthesized in a floating state) having a diameter of 0.1 to 0.5 μm.

However, the plasma treatment time was 5 minutes, and the reaction with the organic polymerizable monomer after plasma treatment was 3 parts by weight of butadiene, 10 parts by weight of acrylamide, 5 parts by weight of acrylic acid,
It was brought into contact with a mixed system of 5 parts by weight of alkylbenzenesulfonic acid and 200 parts by weight of water in a closed system. The reaction temperature is 70
After reacting at ℃ for 40 minutes, washing and drying were performed. The amount of acidic functional groups in the obtained carbonaceous fiber was 77 μeq/9.

Example 4 In Example 3, methacrylic acid 7 was used instead of acrylic acid.
Parts by weight were used, and the reaction temperature was raised to 80°C. The amount of acidic functional groups in the obtained carbonaceous fiber was 53μeq/t
Met.

Example 5 The carbonaceous fiber 11C30Mrad used in Example 3 was irradiated with an electron beam, and after this treatment, 5! 60 parts by weight, a mixed system of 8 parts by weight of acrylic acid, 5 parts by weight of vinyl chloride, 5 parts by weight of alkylbenzenesulfonic acid, and 200 parts by weight of water.
℃ for 30 minutes. The amount of acidic functional groups in the obtained carbonaceous fiber was 28 μsq/P.

(Effects of the Invention) The carbonaceous fiber of the present invention has a moderate amount of acidic functional groups, and the organic polymerizable monomer is added through an addition reaction.
It has good adhesion and wettability with male gums and resins, so it is easy to composite and mix with these materials, and when used as a composite material, the mechanical properties are favorably improved. Therefore, it is extremely useful as a reinforcing material for resins, male rubber, etc. In addition, it is effective as a surface functional fiber as it also adsorbs various compounds.

Claims (1)

[Claims] By adding an organic polymerizable monomer, acidic functional groups can be
Carbonaceous fibers having ~800 μeq/g and a diameter of 0.01 to 4 μm