JP4469952B2 - Solid phase growth carbon fiber and method for producing the same - Google Patents

Description

  The present invention relates to a solid growth carbon fiber and a method for producing the same. More specifically, a raw material mainly composed of sodium terephthalate is pyrolyzed at a temperature of 500 to 1000 ° C. to form a composite of carbon fiber and sodium carbonate compound, which is washed with water to remove sodium carbonate. And drying, the present invention relates to an ultrafine solid-phase grown carbon fiber of 10 to 200 nm and a method for producing the same.

  Carbon fiber is a fiber made by heating organic carbon in an inert gas at 700-1800 ° C. and carbonizing, and is known as a fibrous carbon material with a fine graphite crystal structure that is light, strong and heat resistant. It has been. Organic fibers are made by fiberizing known acrylic resins such as clothing, pitches from petroleum and coal.

  Conventional fibrous carbon materials include carbon fibers obtained by thermally decomposing acrylic fibers and the like (see, for example, Patent Document 1), and gas phases obtained by thermally decomposing organic compounds such as benzene in the presence of a catalyst. Examples include grown carbon fiber. However, the former requires many processes such as a spinning process for forming fibers and an infusibilization treatment to prevent melting during heat treatment, and the latter causes carbon fibers to be deposited on the surface of the fluidized catalyst. There were drawbacks such as difficulty in producing carbon fibers.

In addition, a method has been proposed in which terephthalic acid in an alkali-reducing processing waste liquid of a polyester fabric is separated as a calcium salt and carbonized to be used as a carbon material (Patent Document 2). However, in this method, it is necessary to add calcium chloride after adjusting the pH, and the number of steps is large. Further, the manufactured carbide is not carbon fiber but carbide, and does not make carbon fiber.
JP 2005-126857 A Japanese Patent No. 2694601

  Conventional carbon fiber production methods have drawbacks such as requiring many production processes such as a spinning process and an infusibilization process, and producing a large amount of carbon fibers. From the above technical background, the present invention achieves the following objects.

  An object of the present invention is to provide a method for producing solid-phase grown carbon fiber that does not require a spinning process, an infusibilization process, or the like.

  Another object of the present invention is to provide a method for producing solid-phase grown carbon fiber at a low cost.

  Another object of the present invention is to provide a method for producing solid-phase-grown carbon fibers using waste such as PET bottles as a raw material.

  Another object of the present invention is to provide a method for producing solid-phase-grown carbon fiber using sodium terephthalate as a raw material, which produces carbon fiber only by heating sodium terephthalate in an inert gas and carbonizing it. .

The solid-phase-grown carbon fiber of the present invention and its production method are obtained by thermally decomposing a raw material mainly composed of sodium terephthalate crystals at a temperature of 500 to 1000 ° C., washing it with water, and then drying it. It produces ultrafine carbon fibers of 10 to 200 nm. That is, the present inventors simply pyrolyze a raw material mainly composed of sodium terephthalate at a temperature of 500 to 1000 ° C., wash it with water, and dry it to obtain an ultrafine carbon fiber of 10 to 200 nm. Found that can be manufactured. No method for producing such a carbon fiber has been reported so far. This production method was found to be an excellent production method in which the alkaline waste liquid generated during the washing treatment can be used again for preparing the sodium salt of terephthalic acid and hardly generates waste.

  The method for producing solid-phase-grown carbon fibers of the present invention makes it possible to produce a large amount of ultrafine carbon fibers that have never been obtained by a simple operation. Furthermore, almost no waste liquid or waste is generated in the manufacturing process.

  In the present invention, a raw material mainly composed of sodium terephthalate is thermally decomposed at a temperature of 500 ° C. or higher to form a composite of carbon and a sodium carbonate compound, which is further washed with water to remove sodium carbonate. As a result, an ultrafine carbon fiber of 10 to 200 nm can be produced.

  2 mol of sodium hydroxide aqueous solution was added to 1 mol of terephthalic acid to prepare a sodium terephthalate aqueous solution, and this solution was dried to obtain sodium terephthalate crystals. The crystals were put in an alumina boat and heat-treated at 600 ° C. for 2 hours in a horizontal furnace in an argon atmosphere, and then allowed to cool. The product was washed with water to remove sodium carbonate produced by the reaction and dried to prepare carbon particles having the same shape as the raw material sodium terephthalate crystals. The relationship between the heat treatment temperature and the yield of pyrolyzate and carbon particles (fibers) is shown in FIG.

  FIG. 2 shows a scanning microscope photo showing the sodium terephthalate raw material and the produced carbon fiber, FIG. 2 (a) is the sodium terephthalate raw material, FIG. 2 (b) is the obtained carbon particles, FIG. 2 (c) shows the fracture surface of the carbon particles, and FIG. 2 (d) shows the carbon fibers in the carbon particles. The shape of the carbon fiber obtained was different depending on the production conditions, and as the heat treatment was performed at a higher temperature, the carbon fibers tended to have a more bonded structure. And it became clear that it became a structure similar to activated carbon fiber with micropores developed by the reaction between carbon and sodium carbonate at high temperatures. FIG. 3 shows the relationship between the heat treatment temperature and the specific surface area.

Table 1 shown below is an ancestor analysis result of the carbon fibers produced in this example.

  By using this method, it is possible to improve a complicated manufacturing process and a manufacturing method that is not suitable for mass production, which have been problems in the conventional method, and a carbon fiber that is finer than conventional commercially available carbon fibers. can get. Further, terephthalic acid used as a raw material for this method is a relatively inexpensive organic raw material that is industrially used as a PET resin raw material, and has an advantage in terms of manufacturing cost. Further, sodium terephthalate obtained by decomposing waste such as PET bottles may be used as a raw material.

FIG. 1 is a diagram showing X-ray diffraction results of raw materials, pyrolysates, and carbon fibers. FIG. 2 shows a scanning microscope photo showing the sodium terephthalate raw material and the produced carbon fiber, FIG. 2 (a) is the sodium terephthalate raw material, FIG. 2 (b) is the obtained carbon particles, FIG. 2 (c) shows the fracture surface of the carbon particles, and FIG. 2 (d) shows the carbon fibers in the carbon particles. FIG. 3 is a graph showing the heat treatment temperature dependence of the specific surface area of the carbon fibers produced in Example 1.

Claims (2)

Solid-phase grown carbon fiber produced by heating and carbonizing sodium terephthalate crystals in an inert gas to 500 ° C. to 1000 ° C. ,
The solid phase growth carbon fiber is an ultrafine fiber having a diameter of 10 to 200 nm. In the manufacturing method of the sodium terephthalic acid crystals were heated to 500 to 1000 ° C. in an inert gas solid-phase growth carbon fiber that is carbonized,
The method for producing solid-phase-grown carbon fiber, wherein the solid-phase-grown carbon fiber is an ultrafine fiber having a diameter of 10 to 200 nm.

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