JP3519243B2 - Spherical carbon material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spherical carbon material and a method for producing the same, more specifically, a particle diameter of 150 to 25.
Spherical charcoal of high purity and strength and abrasion resistance obtained by carbonizing and firing 00 μm spherical phenol resin
Material and manufacturing method thereof.

[0002]

Carbon powders obtained by carbonizing natural products such as natural graphite, quartz, coke, various pitches or coconut shells are
It has conductivity, and has excellent heat resistance, chemical resistance, or abrasion resistance, so it is a heat-resistant filler, composite material reinforcement,
Automotive parts as slidability improving materials or conductivity imparting materials,
Widely used in the fields of electronic parts, industrial machinery, office equipment, etc.

Further, a phenol resin such as a resole resin or a novolac resin may be heat-cured by using a curing agent such as hexamethylenetetramine as required. In this case, it is a synthetic resin raw material and is highly carbonized. Since it is possible to obtain pure carbon, it is preferably used in the field of electronic parts and the like. In addition, as the carbon material using the synthetic resin raw material, a spherical carbon material having a particle diameter of about 150 μm or less is used because it has improved dispersibility in resin or rubber and fluidity.

[0004]

However, conventional carbon powders obtained by carbonizing natural products such as natural graphite, quartz, coke, various pitches or coconut shells contain sulfur, halogen compounds or metal oxides as components. Since it is contained in a large amount, there are problems such as metal corrosion in applications such as electronic parts and mechanical parts. In addition, since those using these natural raw materials are lumps having an indefinite shape, they need to be crushed before or after carbonization and firing, and the fracture surface of the obtained carbon powder is sharp. Not only is the dispersibility and flowability in rubber poor, but the wear resistance may be impaired in the applications of sliding materials and sealing materials. Further, the conventional carbon powders tend to agglomerate with each other when mixed with resin or rubber, which is also a cause of product variations.

Further, as described above, a carbon material using a synthetic resin raw material is also used, but it has a low carbonization yield and requires the crushing process as described above, so that it is not practical in terms of performance and cost. In addition, in applications such as reinforcing materials and sliding materials, materials having higher mechanical strength are required.
In addition, even among carbides made from synthetic polymers, spherical ones with a particle diameter of about 150 μm or more have not been obtained, and there is a limit to the design of the packing density that maximizes, Carbide scatters during the process
There were drawbacks such as significantly contaminating the work environment.

The inventors of the present invention have completed the present invention as a result of intensive studies focusing on such problems, and an object of the present invention is to provide automobile parts, electronic parts, industrial machines, office equipment, etc. In the field, when used as a heat resistant filler, a reinforcing material for composite materials, and a sliding property improving material, dispersibility in resin,
An object of the present invention is to provide a high-strength spherical carbide having excellent fluidity, a very high packing density, and a method for producing the same. Further, it is to provide a spherical carbide and a method for producing the same that can reduce the scattering of the carbide from opening to charging and improve the operability during operation. Still other objects will be apparent from the following description.

[0007]

[Means for Solving the Problems] The above object, the breaking strength
100 kg / cm ² or more, particle diameter 150 to 2000 μ
m spherical carbon material, more specifically, a breaking strength of 100 Kg / cm ² or more obtained by carbonizing a spherical phenol resin having a particle diameter of 150 to 2500 μm
This is achieved by using a spherical carbon material having a diameter of 150 to 2000 μm .

Further, the above-mentioned other object is to obtain a particle diameter of 150 to
Fracture strength 10 characterized by carbonizing a 2500 μm spherical phenol resin at 500 ° C. or higher in a non-oxidizing atmosphere
This is achieved by a method for producing a spherical carbon material having a particle diameter of 150 to 2000 μm and a particle diameter of 0 kg / cm ² or more .

Here, the spherical phenol resin is a spherical resin produced by a chemical reaction containing aldehydes and phenols as main components, and the phenol resin powder is mixed with a binder and mechanically dumped by a tumbling granulation method. It is different from the one granulated and shaped. The spherical carbide produced by the present invention becomes a heat-resistant filler having a great effect, a reinforcing material of a composite material, a sliding improving material, or a conductivity-imparting material by being mixed with a resin.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
Generally, the phenol resin is roughly classified into a resole resin, a novolac resin, and other special phenol resin and modified products, and the spherical phenol used for producing the carbon material of the present invention. The resin manufacturing method is as follows.

The particle diameter of the spherical phenol resin is 15
A method suitable for producing particles having a particle size of 0 to 2500 μm is, for example, a method described in JP-A-63-48320, in which a certain substance is used as a nuclear substance and phenols and aldehydes are present in the presence of a dispersant. It can be obtained by subjecting the condensation reaction to a condensation reaction, the condensation product is aggregated around the nuclear substance to generate a powder and granules, and then dehydration and drying. As nuclear material,
For example, phenol resin, glass particles, SiC, mesophase, alumina, graphite, phlogopite, etc. can be used.

The spherical phenol resin having a particle diameter of 150 to 2500 μm used for obtaining the carbon material of the present invention is obtained by sieving the spherical phenol resin obtained by the above-mentioned method,
It can be obtained by removing those having a thickness of less than or equal to μm and greater than or equal to 2000 μm. The spherical phenol resin used for producing the carbon material of the present invention usually has a particle size of 150 to 2000 μm, but the suitable particle size varies depending on the use of the produced carbide.

Since the phenols, aldehydes, etc., which are the raw materials of the spherical phenol resin used for producing the carbon material of the present invention, can be those having a low impurity content, the obtained phenol resin can be used. The content of impurities is significantly lower than that of natural products such as coconut shell and coal, which are conventional carbon material raw materials, and stable products with little difference between lots and between lots can be obtained.

By subjecting the spherical phenol resin obtained as described above to heat treatment at 500 ° C. or higher, the desired spherical carbon material can be obtained. This spherical carbon material is different from the conventional spherical carbon material in which finely pulverized carbon is mixed with a binder and then mechanically granulated by a rolling granulation method.

The spherical carbon material of the present invention can be obtained by carbonizing a spherical phenol resin in a non-oxidizing atmosphere. The carbonization temperature is usually at least 500 ° C. in a non-oxidizing atmosphere,
Preferably, it is carried out by raising the temperature to 2000 ° C. or lower, but if the maximum temperature of carbonization and firing is lower than 500 ° C., the desired conductivity and mechanical strength are excellent even if held for a long time.
A spherical carbon material is difficult to obtain and is not preferable. The setting of the above maximum temperature can be arbitrarily selected according to the purpose of use of the spheroidized product,
In the case of 500 to 700 ° C., the semiconductor has conductivity and has good affinity with resin or rubber. Further, when the temperature is 700 ° C. or higher, high conductivity is obtained. Firing at a temperature of 1500 ° C. or higher is not preferable because it requires more energy than necessary. Two
Firing at a temperature of 000 ° C. or higher is not preferable because the graphitization proceeds and the mechanical strength decreases.

The carbonization and firing in the present invention is carried out in a non-oxidizing atmosphere, usually in an atmosphere substantially free of molecular oxygen, for example, an atmosphere mainly containing at least one selected from nitrogen, helium, argon, hydrogen and carbon monoxide. It is carried out in an atmosphere containing as a gas. The temperature and atmosphere for carbonization and firing have a great influence on the properties of the obtained spherical carbide.

The particle diameter of the carbon material of the present invention is 150 to 20.
The particle size is 00 μm, and the preferable particle size is significantly different depending on the respective application such as composite material, gear, and bearing. When the particle diameter is 2000 μm or more, it becomes difficult to make the shape of the phenol resin molded body, which is a raw material of the carbon material , into a true spherical shape, and the amount of contaminants other than the spherical body increases. Degradation occurs. Further, if the particle diameter is 2000 μm or more, the temperature difference between the central portion of the sphere and the outer peripheral portion is large during carbonization, and carbonization is unevenly performed, resulting in a reduction in crushing strength, a reduction in wear resistance and the like. Further, if the particle diameter is 2000 μm or more, the decomposed gas of the resin generated from the inside of the sphere does not quickly diffuse to the outside of the sphere, so bubbles are generated inside the sphere or cracks are generated on the surface of the sphere, which is not preferable.

If the particle diameter is 150 μm or less,
It is not preferable because secondary agglomeration of carbon materials occurs, it is difficult to increase the packing density when used as a composite material, and there is an adverse effect on the work environment such as scattering to the surroundings during handling work.

The ash content of the carbon material of the present invention is 0.5% or less, preferably 0.3%, and most preferably 0.2% or less. When the ash content is 0.2% or less, the amount of metal oxides, sulfur, etc. in the carbonaceous material is small, so that it is possible to reduce the risk of corrosion in the fields of electronic parts, mechanical parts, etc. .

The crushing strength of the carbon material of the present invention is 100 kg.
/ Cm ² or more, preferably 130 kg / cm ² or more, preferably 150 Kg / cm ² or more is good. When the strength is low, it is not preferable because it is crushed and pulverized during use when it is used as a reinforcing material of a composite material, a sliding property improving material, etc. in automobile parts, electronic parts, industrial machines and the like.

The carbon material of the present invention is mixed with an epoxy resin,
After producing the molded body, the compression strength evaluated by the method described below is 500 Kg / cm ² or more, preferably 600 Kg / cm ^2.
cm ² or more , and more preferably 700 Kg / cm ² or more . When the compressive strength is lower than 500 Kg / cm ² or more, the resin molded product is crushed and pulverized during use as in the case where the crushing strength is low, which is not preferable.

[0022]

EFFECTS OF THE INVENTION The spherical carbon material obtained in the present invention is obtained by heating, carbonizing and firing a spherical phenol / formaldehyde resin, and therefore has a high purity with almost no sulfur, halogen compounds and metal oxides. . Therefore, for example, wiring and metal in electronic parts, electric parts, office equipment, etc. mixed with resins such as phenol resin, epoxy resin, polyethylene, polypropylene, polybutylene terephthalate, polyamide, Teflon, polyphenylene sulfone and various rubbers are used. It is not corroded and is most suitable as a carbon material of metal carbide such as silicon carbide.

The spherical carbon material of the present invention is substantially isotropic carbon. This can be confirmed by the presence of a broad peak in the vicinity of the diffraction angle (2 theta) of 23 to 24 ° C. in the X-ray diffraction pattern, but it is recognized as so-called glassy carbon from the glassy luster of the fracture surface of the particles. To be The carbon fine particles in the present invention have a small specific gravity of 1.4 to 1.6 like other glassy carbons and are very excellent in mechanical strength and wear resistance, so that they are gears, bearings, contacts, rolls, mechanical seals. It is also highly effective as a sealing material such as, and a filler such as a sliding material.

Further, since the spherical carbonized material of the present invention has a spherical shape and can be freely combined with a particle size distribution of 150 to 2000 μm by sieving, it is possible to design a combination that maximizes the packing density. Have. Further, since the dispersibility in various resins and rubbers and the fluidity are remarkably superior to other carbon powders, they can be blended in a large amount. For the above reasons, a resin composition having high density and high fluidity can be manufactured.

In the case of ordinary carbon powder, when mixed with resin or rubber, the fluidity and dispersibility decrease remarkably as the compounding amount increases, and the strength of the obtained molded product is impaired. It is surprising that the spherical carbide in the present invention rather improves the dispersibility and fluidity of the resin or rubber due to the shape and properties described above.

Further, the conventional spherical carbon powder has a fine particle diameter of 150 μm or less, and the amount of resin or rubber filled therein does not rise as expected, and scattering of the powder is unavoidable during opening and charging. However, there is a drawback that the working environment is contaminated by black powder. As for the spherical carbide in the present invention, it is possible to mix particles having different diameters of the most closely packed particles by sieving at an appropriate ratio according to the application, and it is possible to design a combination that maximizes the packing density.
Further, since it has a sufficiently large particle diameter, the above-mentioned contamination is unlikely to occur and the working environment is remarkably improved.

The spherical carbon material of the present invention having the above-mentioned characteristics is compounded with various resins and rubbers to obtain a reinforcing material, a sealing material, a sliding material, a corrosion resistant material, a conductive material, an electrode material and a coloring material. It can be used in an extremely wide range.

(Measurement Evaluation Method) Next, the measurement evaluation method used in the present invention will be described below.

(1) Ash content About 1 g of a sample dried at 105 ° C. for 2 hours was precisely weighed in a platinum crucible, ashed at 700 ° C. for 2 hours, and precisely weighed again to obtain the ash content. However, among the nuclear substances added when producing the spherical phenolic resin, if the residual components due to the above ashing are included, the amount of ash derived from this nuclear substance is subtracted from the amount of ash of the spherical carbon material. Was the ash content of the spherical carbon material.

(2) About 1 g of a sample dried for 2 hours at an impurity content concentration of 105 ° C. was precisely weighed in a platinum crucible and ashed at 700 ° C. for 2 hours. Heat on plate. Nitric acid is added before it is dried and diluted 7 to 8 times with ultrapure water.
When the liquid volume becomes about 1/3, ultrapure water is added again, about 1 ml of nitric acid is added, and after heating for 1 hour, ultrapure water is added and the total amount is adjusted to 50 ml. A blank is prepared by the same operation, and the measurement result of each sample is corrected. Quantification of impurities was carried out by ICP emission analysis using an element whose detection was confirmed by fluorescent X-ray qualitative analysis, using a dual monochrome ICP emission analyzer P-5200 type manufactured by Hitachi, Ltd.

(3) Fracture strength measurement method Strength measurement is carried out by KATO TECH CO. It was measured by a compression tester (KES-FB3) manufactured by LTD. The crushing strength evaluated by the strength measurement was calculated by the following formula from the load value at the time of crushing the carbon material and the diameter of the carbon material. Tensile strength: σ [kg / cm ² ] = 2P / πd ² P: Load [kg] d: Pellet diameter [cm]

(4) 80% by weight of filling carbon material, epoxy resin (Epomic R-14
(0: manufactured by Mitsui Petrochemical Co., Ltd.) A sample adjusted to 20% by weight was mixed by a Shinagawa mixer and the state of the mixture was observed. Also,
A part of the mixture was sampled, the resin portion was washed off with hexane, and each carbon material was observed with a stereoscopic microscope.

(5) Compressive strength of resin mixture 45% by weight of Samples 1 to 7 and epoxy resin (Epomic R
-140: Mitsui Petrochemical 100 parts, dimiandiamide 3.5 parts, benzyldimethylamine 0.3 parts) 55
Samples prepared by weight% are mixed, and each sample is heat-treated under a pressure of 200 kg / cm2 for 120 minutes using a mold which has been heated in advance to 180 ° C. between a heating press machine to obtain the size. Five test pieces each having a size of 10 mm square and a thickness of 3.5 mm and dimensions of 13 mm × 3 mm × 120 mm were prepared for each, and the electrical resistivity was measured by the voltage drop method according to JIS-R-7202.

(6) Electrical Resistivity of Resin Mixture A resin cured sample prepared by the above method was tested according to JI
The compressive strength was measured according to SK-6911.

(7) Workability at the time of resin molding plate production. Carbide and resin are mixed at the time of manufacturing a molding plate for evaluation of the compressive strength of the resin mixture. Judgment is made from the scattering state of the carbon material to the surroundings at that time. did.

[0036]

【Example】

(Example 1) [Method for producing spherical carbon material] To 40 L of the reaction solution, 30 kg of a mixed aqueous solution containing 18% by weight of hydrochloric acid and 9% by weight of formaldehyde was placed, and phenol was stirred in the flask at 28 ° C. / Water = 1 kg of 90/10 aqueous solution
Was added. After that, when the stirring was continued for a while, it rapidly became cloudy. At the same time as the white turbidity, stirring was stopped and the mixture was left as it was.

The internal temperature gradually increased, and formation of a pink slurry was observed. Then continue stirring 8
The temperature was raised to 0 ° C. and stirring was continued for about 20 minutes. After further washing the contents with water, 60% in 0.2% by weight aqueous ammonia solution
It was treated at a temperature of 60 ° C. for 60 minutes, washed with water, and then dried at a temperature of 200 ° C. for 2 hours to obtain a spherical phenol resin having a diameter of 0.1 to 150 μm.

Further, the resin, phenol, aldehyde and the like were mixed and stirred at the following ratio. Spherical phenol resin / phenol / 92% formaldehyde / hexamethylenetetramine / gum arabic / water = 5/100/40 /
10/1/100. 85 in about 60 minutes with continuous stirring
The temperature is raised to ℃, the reaction is carried out for 60 minutes as it is, the dilution water is added, and after cooling until the internal temperature is lowered, this is filtered off and dried, and further dried until the water content becomes 2% or less. The resin having a particle diameter of 150 μm or less and 2500 μm or more was removed by a sieve to obtain a spherical phenol resin having a particle diameter of 150 to 2500 μm.

Further, this resin is heated to 800 ° C. in a nitrogen stream for 2 hours, and is held at a set temperature of 800 ° C. for 30 minutes for carbonization and sieving.
A spherical carbon material of 0 μm was obtained.

Further sieving gives a particle diameter of 1
50 μm to 500 μm spherical carbon material (Sample 1) and 1
A spherical carbon material (Sample 2) of 000 to 2000 μm was obtained.

3 parts by weight of sample 1 and 7 parts by weight of sample 2 were mixed for 10 minutes to obtain a spherical carbon material mixture (sample 3).

Comparative Example A spherical carbon material (Sample 4) was prepared by the following rolling granulation method, which is a conventional method for manufacturing a spherical carbon material as a comparative example. That is, Composition 1 in which coal fine powder / thermofusible phenol resin / crystalline cellulose / water = 4/3/2/1 were mixed.
0kg revolves at 15 RPM and rotates at 30 RPM for 10 minutes
After kneading (manufactured by Shinagawa universal stirrer Dalton Co., Ltd.), high speed mixer FS-GS-10 manufactured by Fukae Industry Co., Ltd.
Particle diameter 15 by rolling granulation at J agitator rotation speed 300 rpm, chopper rotation speed 3600 rpm for 10 minutes
After obtaining a spherical phenol resin of 0 to 2000 μm, the temperature was raised to 800 ° C. over 2 hours in a nitrogen stream, and the temperature was maintained at the set temperature of 800 ° C. for 30 minutes for carbonization.

(Example 2) In addition to the sample 4 obtained in Example 1 and the comparative example, a commercially available carbon powder was used as a comparative example, and as a cast 5H (Sample 5: manufactured by Tokai Carbon Co., Ltd.), V-XC-.
The ash content was measured using 72R (Sample 6: Cabot) and Ketjen Black EC (Sample 7: Lion Akzo). The results are shown in Table 1. Although the ash content of Sample 1 and Sample 4 is within the range specified by the present invention,
Samples 5 to 7 had a very large ash content and a large amount of impurities.

[0044]

[Table 1]

(Example 3) Using Samples 1 and 4 to 7,
The impurity element content rate was measured. The results are shown in Table 1. It was only samples 1 and 4 that the characteristics of the carbon material were within the range specified in the present invention, and the impurities of other carbon materials were very large.

Example 4 Samples 1 and 4 were evaluated for crushing strength. The results are shown in Table 2, and sample 1
The crushing strength was within the range specified by the present invention, which was higher than that of the rolling granulated product. On the other hand, sample 4 had a low value.

[0047]

[Table 2]

(Example 5) Samples 1 to 7 were evaluated with respect to the filling property into the resin and the workability at the time of filling. The results are shown in Table 3. In sample 5 to sample 7, the resin and the carbon material were not well compatible and could not be mixed. Further, although Sample 4 could be mixed by some means, it was confirmed by microscopic observation after mixing that the shape of the particles had collapsed. Samples 1 to 3 were able to obtain a better mixture than the others.
In particular, Sample 3 had good fluidity after mixing. Sample 1
The filling properties of Nos. 4 to 4 were sufficient, but those of Samples 5 to 7 were insufficient. Regarding workability, samples 1 to 4 were also good, but samples 5 to 7 were insufficient.

[0049]

[Table 3]

Example 6 Samples 1 to 7 were evaluated for the compressive strength of the resin mixture. The results are shown in Table 4. In Samples 1 to 3, the characteristics of the carbon material were within the range specified in the present invention, and in particular, Sample 3 exhibited extremely high compressive strength. Samples 4 to 7 could not obtain sufficient strength.

[0051]

[Table 4]

Example 7 Using the sample used in Example 4, the electrical resistivity was evaluated. The results of each sample are shown in Table 4. In Samples 1 to 3, the characteristics of the carbon material were within the range specified in the present invention, and in particular, Sample 3 exhibited a very low electrical resistivity. The electrical resistivity of each of Samples 4 to 7 was high.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-20680 (JP, A) Japanese Patent Publication No. 61-1366 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C01B 31/00-31/36 C08K 3/04 C08K 7/18 C08L 101/00

Claims (2)

(57) [Claims] 1. A spherical carbon material having a breaking strength of 100 kg / cm ² or more and a particle diameter of 150 to 2000 μm. 2. The spherical carbon material according to claim 1, which is a heat resistant filler, a reinforcing material of a composite material, a slidability improving material, or a conductivity imparting material by being mixed with a resin.