JPS5855108B2 - Carbon material manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a carbon material containing carbon fibers.

The carbon material is made by mixing and kneading carbon powder and binder in an appropriate ratio, molding it, firing the molded product, and graphitizing it if necessary. It is a rare piece of equipment that can be used under conditions such as large mechanical loads, and is machined to produce electrode plates for aqueous electrolysis, carbon for machinery, carbon materials for metals, electrodes (including nipples), structural materials for chemical equipment, It is widely used in many fields such as graphite materials for nuclear reactors and carbon materials for electrical machinery.

Recently, when manufacturing electrodes for dry batteries, a type of product using this carbon material, graphite fibers are added to a mixture of coke, carbon black, and tar pitch, molded, and fired to increase the strength of the resulting product. A method for reducing electrical resistance (Japanese Patent Publication No. 37-2758), and a fired refractory brick made by adding carbon fiber to clay (Japanese Patent Publication No. 382
No. 5997) is disclosed.

Generally, in order for the performance of this carbon material to be improved by carphone fibers, the length of the carbon material is 1 WtTIL or more, preferably 10
It is necessary that carbon fibers of mm or more are uniformly dispersed in the carbon material.

However, when long carbon fibers are used, they tend to become entangled and re-agglomerate, making it difficult to disperse and not uniformly dispersing and arranging them, so the properties of the resulting carbon material do not improve. If a large amount of binder is used to uniformly disperse the carbon fibers, the strength of the resulting carbon material will not increase, and if it is kneaded strongly using a mixer, the carbon fibers will be shredded and powdered. This also has the disadvantage that the properties of the carbon material cannot be improved.

The present invention has the advantage of uniformly dispersing long fibers (about 1-200 AO++ → carbon fibers) into the carbon material without breaking them, thereby reducing their electrical resistance, bending strength, and thermal expansion coefficient. The company succeeded in providing a carbon material with improved mechanical properties, and its gist is that carbon fibers or graphite fibers (hereinafter referred to as carbon fibers) are melted or dissolved in a solvent to form a liquid carbonaceous binder (pitch or resin). The method is characterized in that the surface of the fibers is wetted with a binder by contacting with a binder, the carbon fibers are mixed with carbon powder and a carbonaceous binder, kneaded, and then molded and fired.

Preferably, the binder is one that melts when heated or is a liquid dissolved in a solvent that solidifies at room temperature.

To wet the surface of carbon fibers with a binder, cut the carbon fibers into appropriate sizes and immerse them in a liquid binder, or compress the fibers and impregnate the spaces between the fibers. Either by squeezing out the binder, or by passing a continuous bundle of carbon fibers through a liquid binder, the carbon fibers are passed between rollers to squeeze out the binder associated with the carbon fibers, and then Furthermore, after the binder that has adhered and wetted the carbon fibers is solidified or dried, the resulting carbon fibers are cut into desired dimensions.

The thickness of the carbon fiber monofilament at this time is 1
~8 denier, the number of filaments in the east is i, ooo~is
,oo.

It is preferable that

In order to improve wetting with the binder, the carbon fibers can be surface treated or a surfactant can be added to the binder.

The optimum amount of carbon fiber to be used in the coke material varies depending on the thickness and length of the fiber itself, as well as the type and particle size of the coke used, but it is usually added in an amount of 1 to 20% by weight.

Molding and firing are carried out by conventional methods.

According to the method of the present invention, carbon fibers are melted or dissolved in a solvent and are sufficiently wetted with carbonaceous binders such as pitch and resin in a liquid state, so that they are bonded to carbon powder. When mixed with a kneading agent, carbon fibers do not get entangled even if they are long, and bundles are easily loosened and do not re-agglomerate, and are uniformly dispersed in the kneaded composition, and the carbon fibers are shredded. Never.

Therefore, the carbon material obtained by molding, firing, and optionally graphitizing this kneaded composition has carbon fibers uniformly dispersed therein with no change in length, resulting in good bending strength and electrical resistance. , the thermal expansion coefficient properties can be significantly improved.

Furthermore, according to the method of the present invention, when the carbon fibers are mixed and kneaded with the carbon material and the binder, there is no entanglement or re-agglomeration, so the mixing and kneading can be carried out easily in a short time, and the amount of binder used can be reduced. High-strength, high-modulus carbon fiber (tensile strength 100 kg/
Since the long fibers (those having an elastic modulus of mA or more and an elastic modulus of 10 t/maJa or more) can be uniformly dispersed in the carbon material, various properties of the obtained carbon material can be significantly improved.

Furthermore, the present invention can improve various properties of the product by using carbon fibers treated by the method of the present invention after re-inspection during molding.

Next, embodiments of the present invention will be described with reference to examples, but the present invention is not limited by these examples.

Note that all percentages and parts shown in the text are percentages and parts by weight.

Examples 1 to 3, Comparative Example 1 High-strength carbon fiber manufactured from polyacrylonitrile fibers made of 18,000 1.5-denier monofilaments (tensile strength 300 kg/mi, elastic modulus 20 t/mm)
) is passed through a molten medium pitch (mp, 87°C) bath, and after passing, it is passed between two rollers to extrude and remove the pitch accompanying the fibers, and the pitch is approximately 300% based on the fibers.
A fiber bundle coated with a pitch of

The fiber was then cooled and cut into approximately 10 mrn pieces.

1 part, 3 parts, and 5 parts (all parts by weight of carbon fibers only) of the cut carbon fibers were added to a particle size of 0.
．． 50-50 parts of 0.15mm and 0.074m
50 parts of a compound containing 70% of θ less than m was added to the blended pitch coke and mixed.

A medium pitcher (mp, 87°C) was added to each of the resulting mixed compositions.
Add 40 parts and knead for 50 minutes, then 50 parts φ x 30
The molded body was extruded to a thickness of 0 mm, fired at 800°C, and further graphitized at 2600°C. Various properties obtained were determined and are shown in Table 1.

As a comparative example, a material to which no carbon fiber was added was treated according to each example, and various properties of the obtained carbon material were determined according to each example, and the results are shown in Table 1.

The carbon fibers added to the kneaded products of each example maintained their original shape and were uniformly dispersed without being shredded, and it was observed that the carbon fibers were aligned in the extrusion direction in the molded product.

Furthermore, as is clear from Table 1, it was observed that the various properties of the obtained carbon materials of each Example were greatly improved.

Examples 4 to 6, Comparative Example 2 The high strength carbon fibers used in Examples 1 to 3 were
The fiber bundle was wetted with molten medium pitch (mp, 87° C.) in the same manner as in step 3 to obtain a fiber bundle whose surface was coated with a pitch of 300% based on the weight of the fibers.

After cooling, this is approximately 25mm, 50mm, 100rra
It was cut into size n.

Next, 50 parts of pitch coke (with a particle size of 0.3 to 1.0 mm and 5 parts containing 70% of particles with a particle size of 0.074 mm or less)
0 parts) to 100 parts of medium pitch (m-
Three samples were prepared by adding 36 parts (p.87°C) and kneading for 30 minutes.

To each of these preparations, 1 part of carbon fiber cut as described above (indicated by the weight of carbon fiber only) was added and kneaded for an additional 15 minutes. Table 2 shows the properties of the carbon material obtained by molding the carbon material according to the method described above, baking it at 800'C, and then graphitizing it at 2600'C.

As a comparative example, a material to which no carbon fiber was added was treated according to each example, and various properties of the obtained carbon material were determined, and the results are shown in Table 2.

The carbon fibers added to the kneading composition of each example were uniformly dispersed without being shredded, maintaining their original shape, and each molded body had carbon fiber forces opposing each other in the extrusion direction, resulting in a carbon material As is clear from Table 2, it was observed that the various properties of the sample were improved.

Claims (1)

[Claims] 1. Wetting carbon fibers (1 to 200 mm) with a liquid carbonaceous binder, mixing and kneading the carbon fibers with carbon powder and a carbonaceous binder, and then extrusion molding and firing. Characteristic manufacturing method of carbon material. 2. After passing the bundled carbon fibers through a bath of liquid carbonaceous binder and then pressing the carbon fibers,
A method for producing a carbon material, which comprises cutting the carbon fibers to a predetermined size, mixing and kneading the carbon fibers with carbon powder and a carbonaceous binder, and then extrusion molding and firing.