JPH07111026B2 - Method for manufacturing conductive fiber material - Google Patents

Description

The present invention relates to a method for producing a conductive fiber material.

The conductive fiber substance has a function of imparting conductivity as well as reinforcing property, and is useful as a material for a composite material.

(Prior art) With the development of science and technology and the diversification of needs, high-performance and multifunctional materials are actively developed, and various researches on the development of conductive polymer materials are attempted even in the plastics industry. , For example carbon particles or fibers or copper,
A polymer material using a metal powder such as silver or gold as a conductive filler has been proposed. However, when used as fillers other than carbon fibers, they all have the drawback of poor reinforcement. The present inventor has already conducted various studies on fibrous alkali titanate exhibiting excellent properties as a reinforcing filler, has been developing a functional filler, and has made a number of methods for producing conductive fibrous alkali titanate. I have a suggestion. Examples of the main ones include a metal coating method of alkali titanate, a method of producing reduced alkali titanate, a white conductive material, etc., but the present invention is a method of producing reduced alkali titanate disclosed in JP-A-58-135129. It is related to the improved technology of the law.

Japanese Patent Application Laid-Open No. 58-135129, which is a prior art, is characterized in that a mixture of an alkali titanate and a carbon material is heated in a reducing or inert atmosphere and heated and baked at 500 to 1300 ° C. Substantially 80% by weight or more of carbon element is used, and high carbon content fossil components, hydrocarbon compounds, etc. are used.

In this prior art, when a hydrocarbon compound is used,
When heated and baked at 0 to 1300 ℃, thermal decomposition occurs in an inert gas to reduce alkali titanate and at the same time form a carbonaceous film. It was possible to provide a reinforcing filler exhibiting

However, in the prior application, if a hydrocarbon compound that is solid or poor in fluidity at room temperature is used, homogeneous mixing is difficult,
Skill is required for selecting conditions under which the decomposed components of the carbon material are brought into uniform contact with the surface of the alkali titanate. However, when a hydrocarbon compound that is liquid or gas at room temperature and vaporizes during heating and firing is used, the contact between the alkali titanate and the carbon substance becomes uniform, and the reduction of the alkali titanate and the surface of the alkali titanate to the surface of the alkali titanate occur. Although the deposition of carbon substances progresses uniformly, there is a problem with the maintenance of the equipment such as the management of vaporized gas, because it is carried out during heating and firing, and in an atmosphere in which an inert gas, reducing gas, etc. are introduced. The substance also moves at the same time, the contact time with the alkali titanate is reduced, and the carbon substance / alkali titanate ratio in the raw material used becomes large,
There is a drawback that the ratio of carbon material to the production unit is increased and the raw material price is increased.

(Problems to be Solved by the Invention) An object of the present invention is to provide a conductive fibrous material that facilitates homogeneous mixing of a carbon material and a fibrous material and enables uniform deposition of the carbon material on the fibrous material surface. To provide a manufacturing method.

It is another object of the present invention to provide a method for producing a conductive fiber material which reduces the amount of carbon material used as a raw material and facilitates management of the production process such as disaster prevention during heating and firing.

(Means for Solving the Problems) The present invention is to disperse a fiber substance in a hydrocarbon liquid that does not vaporize at 150 ° C. or lower, granulate, and dry the composition by firing under an inert or reducing atmosphere, The present invention relates to a method for producing a conductive fiber material, which comprises forming a carbonaceous film on the surface of the fiber material.

In the present invention, the fibrous substance is a general term for substances having a fiber form that can be provided as a composite material, and the substance having a fiber form has an aspect ratio (fiber length / fiber diameter ratio) of 10 or more. The main fiber materials include glass fiber, alumina fiber, calcium sulfate fiber, rock wool, calcium silicate fiber, asbestos, silicon carbide fiber,
Examples thereof include silicon nitride fiber, silicon boride fiber, alkali metal titanate fiber, alkaline earth metal titanate fiber and the like.

Particularly, as described in detail in JP-A-58-135129, the alkali metal titanate fiber is excellent in heat resistance, heat insulating property, surface smoothness when used as a composite material, and reinforcing property capable of being precisely filled in a fine structure. And sodium titanate, potassium titanate, lithium titanate represented by the general formula M ₂ O · nTiO ₂ (wherein M is an alkali metal, and n is an integer of 2 to 12) and their reduced products are used. Of these, potassium titanate fiber is the most suitable material for the composite material.

The hydrocarbon liquid in the present invention is a liquid or solid at room temperature, and does not vaporize at 150 ° C or lower, and is heated or dissolved in a suitable catalyst and heated to contain a hydrocarbon substance which can be liquefied or dispersed. It means a melt, a solution, an emulsion, a dispersion and the like. Incidentally, the hydrocarbon substance in the present invention is not limited to only the hydrocarbon compound formed by only carbon and hydrogen in the chemical formula, and may be a part of the main chain or the end and side chain of the molecular chain. , Those in which oxygen, nitrogen, sulfur, phosphorus, halogen, etc. are partially incorporated and metal salts of these compounds may be used, and in these compounds, the hydrogen / carbon ratio is 0.5 in terms of the number of atoms.
The above means a compound containing carbon and hydrogen as main components and having a carbon / (element other than carbon and hydrogen) ratio of 5 or more in terms of atoms.

The main ones of these hydrocarbon substances are paraffins,
Olefins, aromatic compounds, heterocyclic compounds and derivatives thereof, and specific examples include liquid paraffins, petrolatum compounds, solid paraffins, polyethylene, polypropylene, polybutene, polybutadiene and other paraffins and their derivatives, for example, Higher fatty acids, higher aliphatic alcohols, aliphatic epoxides, aliphatic esters, aliphatic amines, aliphatic amides, aliphatic ketones, etc .; polyvinyl compounds such as polystyrene, polyvinyltoluene, polyvinyl butyrate, polyvinyl valerate; polybutyl (meta ) Acrylates, polyoctyl (meth) acrylates, stearyl (meth) acrylates, and other acrylates and methacrylates; petroleum pitch, tar and other high-boiling components in fossil components.

The hydrocarbon liquid of the present invention means one obtained by heating or dissolving the above-mentioned hydrocarbon substance according to the present invention in a solvent, or a dispersion liquid of these, and the most preferable dispersion liquid is resource saving and low pollution. Although it is an aqueous emulsion or dispersion from the viewpoint of disaster prevention, it can also be used in the state of organic solutions and dispersions that can be usually used.

In the present invention, a fibrous substance is dispersed in a hydrocarbon liquid, and a dried composition is used, but the purpose thereof is to uniformly mix the hydrocarbon substance and the fibrous substance, and to facilitate the following operation. The above-mentioned mixer and dryer can be applied sufficiently, and as a drying condition, when a solvent or a dispersion medium is used, it may be heated at a temperature higher than the conditions under which these are evaporated.

Incidentally, in the present invention, the most preferable method for these drying steps is a method of spray drying a dispersion of a fibrous substance in a hydrocarbon liquid, or a method of drying after granulation by a usual method. It is preferable because the process control when using the composite material of the conductive fiber material of the present invention is easy.

The ratio of hydrocarbon material to fibrous material is the non-surface area of fibrous material,
Depending on the purpose of use, etc., the hydrocarbon substance is about 0.1 to 500 parts, preferably about 1 to 200 parts, relative to 100 parts by weight of the fiber substance (hereinafter abbreviated as "part"). Is effective in reducing the amount of carbon to express conductivity, but the carbonaceous film becomes discontinuous because the amount of carbon material is insufficient to sufficiently coat the surface of the fibrous material with the carbonaceous film, resulting in a decrease in conductivity. On the other hand, when the amount of the hydrocarbon substance is too large, it means that wasteful raw materials are used and the economical efficiency is poor, and in the method of the present invention, the hydrocarbon substance used is effectively changed into a carbonaceous film on the surface of the fiber substance Therefore, the carbonaceous film becomes thicker than necessary, which reduces the aspect ratio and the reinforcing effect.

In the present invention, the reducing or inert atmosphere, for example, hydrogen gas, a reducing gas atmosphere such as carbon monoxide gas, nitrogen gas,
An inert gas atmosphere containing substantially 90% by mass or more of one or a mixture of two or more of helium gas, argon gas, xenon gas, carbon dioxide gas, etc., particularly nitrogen gas,
A carbon dioxide atmosphere is preferred. When the hydrogen gas atmosphere is used, it is necessary to completely replace the oxygen in the reaction vessel with an inert gas.

In the present invention, the reaction is continuously or stepwise heated to a predetermined temperature necessary for forming the carbonaceous film, and a desirable temperature as the predetermined temperature is about 700 to 1200 ° C.,
A desirable predetermined temperature holding time is about 10 to 120 minutes.

After heating and firing at a predetermined temperature, in cooling the reaction system and collecting the target product, it is not necessary to maintain the cooling step in a reducing atmosphere, but in an inert gas atmosphere, 300 ° C. or less, preferably 2
It is better to cool to below 00 ° C, and if taken out at a high temperature, the carbonaceous film may come into contact with oxygen in the air and burn.

Incidentally, in the present invention, additives such as a dispersant, a dispersion stabilizer, a plasticizer, and an antifoaming agent which are usually used may be used together when the fiber substance is dispersed in the hydrocarbon liquid. You may add the carbon substance which accelerates | stimulates, the catalyst etc. which promote formation of a carbonaceous film.

(Examples) Hereinafter, examples and comparative examples will be described in detail. "Parts" means "parts by weight".

Example 1 5 parts of potassium titanate (manufactured by Otsuka Chemical Co., Ltd., Tesmo D) was added to 100 parts of 5% aqueous emulsion of fluid paraffin (viscosity 10 poise, 20 ° C.) to obtain a homogeneous dispersion.
This dispersion was spray-dried to obtain a granulated product in which the surface of potassium titanate having a particle size of 0.3 mm was coated with fluid paraffin. Next, the atmosphere in a rotary tubular furnace with an inner diameter of 30 mm was adjusted to 900 ° C. after adjusting the atmosphere with nitrogen gas, and the above granules were supplied at a rate of 10 g / min so that the temperature range of substantially 900 ° C. was passed in 20 minutes. After heating and firing, by cooling in a nitrogen atmosphere in a stocker connected to a tubular furnace to 200 ° C. or less, a black color shows a volume resistivity value of 2.4 × 10 ⁻² Ωcm under 100 kg / cm ² pressure, A conductive fiber material having a carbonaceous membrane of 0.30 g / g (carbonaceous membrane / potassium titanate) with respect to potassium titanate was obtained.

Comparative Example 1 The same amount of fluidized paraffin and potassium titanate was used, but the same procedure as in Example 1 was carried out except for the granulation treatment. As a result, the volume resistivity and the formation of the carbonaceous film were 7.6 × 10 ⁰ Ωcm and 0.08 g, respectively. / g
When used as a material for a composite material, about 1% of agglomerates were present, and there was some problem in using it as a material for a precise composite material.

Examples 2 to 4 Table 1 shows the results obtained by the same method as in Example 1 except that the fluid paraffin was changed to another hydrocarbon substance.

Comparative Example 2 Table 1 shows the results obtained in the same manner as in Comparative Example 1 except that polypropylene glycol (PPG, molecular weight 2000) was used as the hydrocarbon substance.

Example 5 10 parts of potassium titanate (Teismo D) was homogeneously dispersed in a hydrocarbon liquid consisting of 10 parts of petrolatum (dropping point 81 ° C.) and 90 parts of 1,1,1-trichloroethane, and then heated at 60 ° C. By granulating, the surface of potassium titanate was covered with petrolatum to obtain a granulated product having a particle size of 3 mm. By heating and firing in the same manner as in Example 1 below, it is black and has a volume resistivity value of 4.
A conductive fiber material with a carbon material film of 7 × 10 ^-2 Ωcm and 0.27 g / g was obtained.

(Effects of the Invention) The conductive fiber material according to the present invention provides a material having conductivity without losing any physical properties of the fiber material as a raw material, particularly the reinforcing effect such as aspect ratio when used as a composite material. It has excellent compatibility with needs such as antistatic, static electricity removal and conductive materials.

Further, compared to the prior application technology that the present inventors have already proposed, a carbonaceous film is effectively formed on the fibrous surface, the carbon material used as a raw material is reduced, and a manufacturing process such as disaster prevention during heating and firing. Is easy to manage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukiya Haruyama 463 Kagasuno, Kawauchi Town, Tokushima City, Tokushima Prefecture Otsuka Chemical Co., Ltd. Tokushima Plant (56) Reference JP-A-61-55218 (JP, A) 58-98476 (JP, A)

Claims (3)

[Claims] 1. A carbonaceous film is formed on the surface of a fibrous substance by dispersing the fibrous substance in a hydrocarbon liquid that does not vaporize at 150 ° C. or lower and firing the granulated and dried composition in an inert or reducing atmosphere. A method for producing a conductive fiber material, the method comprising: forming a conductive fiber material. 2. The method for producing a conductive fiber material according to claim 1, wherein the hydrocarbon is a petrolatum-based material. 3. The method for producing a conductive fiber material according to claim 1, wherein the fiber material is an alkali titanate fiber.