JPH09129029A - Conductive powder composition and conductive resin composition containing the same - Google Patents

Abstract

(57) [Abstract] [Problem] Volume resistivity of 1 when blended with resin.
To provide an inexpensive conductive powder composition which exhibits good mechanical strength when the resin is Ω · cm or less and is a molded product, and a conductive resin composition containing the same. SOLUTION: The conductive powder composition comprising 100 parts by weight of petroleum coke powder and 20 to 60 parts by weight of carbon black and 20 to 50 parts by weight of carbon fiber, and 100 parts by weight of a thermoplastic resin. A conductive resin composition comprising 50 to 150 parts by weight of the conductive powder composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conductive powder composition which, when added to a thermoplastic resin, can impart high conductivity to the resin and enhance mechanical strength, and a conductive powder composition. The present invention relates to a conductive resin composition.

[0002]

2. Description of the Related Art Recent electronic devices such as computers, audio equipment, and home electric appliances have come to operate with a small current due to high integration of electronic circuits and elements, and moreover, the housings of these electronic devices. Moreover, because of its light weight, cost reduction, mass production, and the like, plastic products that transmit electromagnetic waves are often used, and malfunctions and the like are more likely to occur due to external electromagnetic waves.

For this reason, many attempts have been made to impart conductivity to a plastic molded product which is an insulator, and as one of them, a so-called conductive resin in which a conductive filler is filled and dispersed in a resin has been proposed. . As the conductive filler, a metal type filler and a carbon type filler (for example, JP-A-60-118744) are generally used. Although metal-based fillers are suitable in terms of imparting high conductivity, they are expensive and have a large specific gravity, which reduces the conductivity due to damage to the filler during molding, and damages the screw and mold. However, there was a drawback of causing wear.

On the other hand, carbon black or graphite scarcely damages or abrades the screw or die. However, even if general carbon black such as acetylene black or oil furnace black is added to the resin, it is difficult to reduce the volume resistivity value to 1 Ω · cm or less, and high conductivity of the electromagnetic wave shielding material, electrodes, etc. It could not be used for the required purpose.

Although graphite itself has good conductivity, it is necessary to increase the amount of graphite to obtain a conductive resin composition having a volume resistivity of 1 Ω · cm or less. However, if the content is increased, the mechanical strength of the resin composition is significantly reduced.

Further, among the carbon blacks, Ketjen Black EC has a drawback that the mechanical strength of the resin composition is remarkably deteriorated although a satisfactory conductivity can be obtained with a small amount of the compound.

When carbon black and graphite are used in combination, although high conductivity can be obtained at a low filling rate as compared with graphite alone, the mechanical strength of the molded article is also reduced. In addition, although carbon fibers are suitable for improving mechanical strength, they need to be filled to a certain degree in order to exhibit high conductivity, which increases the cost and makes the fibers difficult to mix when mixed with a resin material. It had a drawback that it was often broken and the conductivity was not sufficiently improved. Further, there is an inexpensive carbon-based filler that uses coal coke (JP-A-6-251620), but there is a problem in mechanical strength.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the above drawbacks, and an object of the present invention is to have a volume resistivity of 1 Ω · cm when compounded with a resin.
An object of the present invention is to provide an inexpensive conductive powder composition which exhibits good mechanical strength when the resin is used as a molded article, and a conductive resin composition containing the same.

[0009]

Means for Solving the Problems As a result of repeated trial manufacture and research for solving the above problems, the present inventor found that petroleum coke,
The inventors have found that a conductive powder composition in which a predetermined amount of carbon black and carbon fibers are mixed can exhibit high conductivity and good mechanical strength when blended with a resin, and have conceived the present invention.

That is, the present invention relates to petroleum coke powder,
Preferably 100 parts by weight of petroleum coke powder having an average particle size of 1 to 200 μm, carbon black, preferably dibutyl terephthalate oil absorption of 100 to 200 ml / 100 g.
20 to 60 parts by weight of carbon black, carbon fibers, preferably short fibers having a fiber length of 1 mm or less 20 to 50
A conductive powder composition containing 100 parts by weight of a thermoplastic resin, and a conductive resin composition containing 50 to 150 parts by weight of the conductive powder composition with respect to 100 parts by weight of a thermoplastic resin. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Petroleum coke blended with the conductive powder composition of the present invention is a thermal decomposition (coking) of heavy oil.
The raw coke is 1000-3000.
So-called calcined coke, which is calcined at a temperature of ° C and does not contain volatile matter, is preferably used.

These petroleum cokes are pulverized by a pulverizer such as a ball mill, a vibration mill and a jet mill and used in the form of powder. Particularly, the average particle diameter is 1 to 200 μm.
Those finely pulverized to m can be preferably used.

In the present invention, various carbon blacks such as acetylene black, Ketjen black EC and oil furnace black can be used as the carbon black. These carbon blacks
In general, commercially available products can be used as they are, but in particular, dibutyl terephthalate oil absorption (measured by the method specified in JIS K6221) is 100 to 200 ml /
It is preferable to use mg in the case of compounding with a resin because it has high fluidity, and it is possible to maintain good molding processability of the resin after compounding.

The carbon fiber of the present invention is PAN.
Although any of a system, an isotropic pitch system, and a liquid crystal pitch system can be used, a liquid crystal pitch system carbon fiber is preferable from the viewpoint of exhibiting high conductivity, improving mechanical strength (particularly impact strength), and cost. The fiber length is preferably 1 mm or less so that the resin can be mixed at once. If the fiber length is too long, the fibers and the powder are separated when they are collectively mixed with other powder, or the fibers are broken when they are mixed with a resin, which is not desirable.

In the present invention, petroleum coke, especially calcined coke, has a large conductivity and is very inexpensive as compared with other carbon-based fillers. By adding carbon black to this, carbon black enters between the particles of the petroleum coke and serves to connect the petroleum coke particles, and by adding a carbon fiber having a short fiber length, the above-mentioned conductivity is improved. The mechanical strength can be improved without impairing it. Furthermore, by using carbon fibers having a short fiber length, petroleum coke and carbon black can be kneaded together with the resin, and the fibers do not break during kneading.

The mixing ratio of the conductive powder used in the present invention is 20 to 60 parts by weight of carbon black and 20 to 50 parts by weight of carbon fiber to 100 parts by weight of petroleum coke. If the amount of carbon black is less than 20 parts by weight, high conductivity will not be exhibited, and if it is more than 60 parts by weight, the kneadability with the resin will deteriorate. If the amount of carbon fiber is less than 20 parts by weight, sufficient mechanical strength will not be exhibited, and
If the amount is more than the weight, the cost becomes high. For mixing petroleum coke, carbon black and carbon fiber, a commonly used mixing device can be used.

The conductive powder composition of the present invention is appropriately selected and mixed in the range of 50 to 150 parts by weight with respect to 100 parts by weight of the thermoplastic resin. If the amount is less than 50 parts by weight, high conductivity cannot be exhibited, and if it is more than 150 parts by weight, the mechanical strength is lowered.

The conductive powder and the resin can be mixed by using a generally used single-screw kneading extruder or a twin-screw kneading extruder. Further, as the thermoplastic resin, for example, polypropylene, polyethylene, polystyrene,
For example, ABS resin. These conductive resin compositions are manufactured as molded articles by generally known resin molding methods such as calender molding, extrusion molding and injection molding. If necessary, various additives may be added to this composition,
This is commonly known stabilizers, lubricants, processing aids, tougheners,
A modifier, an antioxidant, a cross-linking agent, a cross-linking aid, etc. may be appropriately selected according to the application.

[0019]

Example 1 Petroleum coke powder calcined at 3000 ° C. (average particle size
20 μm) 56% by weight, carbon black (Tokai Carbon Co., # 4500) 24% by weight, liquid crystal pitch-based carbon fiber (Petka, fiber diameter 8 μm, fiber length 210 μm) 20% by weight
Were mixed using a super mixer (Kawata, SM-V-20 type). This powder composition was kneaded and extruded into 100 parts by weight with 100 parts by weight of polypropylene (Diapolymer 4800JG manufactured by Mitsubishi Chemical Co., Ltd.) using a Labo Plastomill to obtain a polypropylene composition. The obtained polypropylene composition pellets were injection-molded into a test piece by an injection molding machine (Yamashiro Seiki Seisakusho, SVA-60-52 type), and the test piece was subjected to Izod impact strength (method specified in JIS K7110). Was measured. The polypropylene composition pellets obtained above were press-molded with a small press (SA-302-S type, manufactured by Tester Sangyo Co., Ltd.) to prepare disc-shaped test pieces (1 mm × 50 mmφ).
Then, the surface resistivity was measured using a Loresta AP (MPC-T400 type, manufactured by Mitsubishi Chemical Co., Ltd.) using this test piece and converted into a volume specific resistivity. The results are shown in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that the conductive powder composition was added to 60% by weight of petroleum coke, 26% by weight of carbon black and 14% by weight of carbon fiber. Izod impact strength and volume resistivity were measured.
The results are shown in Table 1.

Example 3 In Example 1, polypropylene (Diapolymer 480
0JG) instead of polypropylene (Diapolymer N057
(AG) was used in the same manner as in Example 1 to measure Izod impact strength and volume resistivity. The results are shown in Table 1.

Example 4 In Example 2, polypropylene (Diapolymer 480
0JG) instead of polypropylene (Diapolymer N057A
Example 2 was repeated except that G) was used, and Izod impact strength and volume resistivity were measured. The results are shown in Table 1.

Comparative Example 1 Izod impact strength and volume resistivity were measured in the same manner as in Example 1 except that 100 parts by weight of petroleum coke powder alone was mixed with 100 parts by weight of polypropylene. . The results are shown in Table 1.

Comparative Example 2 In Example 1, instead of 75% by weight of petroleum coke and 24% by weight of carbon black, Ketjen Black EC was used.
(Manufactured by Lion Akzo) was mixed in the same manner as in Example 1 except that 25% by weight was mixed and 100 parts by weight of a powder mixture containing no liquid crystalline pitch-based carbon fiber was kneaded with 100 parts by weight of polypropylene. , Izod impact strength and volume resistivity were measured. The results are shown in Table 1.

Comparative Example 3 A powder composition prepared by mixing 75% by weight of petroleum coke and 25% by weight of liquid crystalline pitch-based carbon fiber in Example 1 and adding no carbon black to polypropylene 100 was used.
Izod impact strength and volume resistivity were measured in the same manner as in Example 1 except that 100 parts by weight was kneaded. The results are shown in Table 1.

Comparative Example 4 In Comparative Example 1, polypropylene (Diapolymer 480
0JG) instead of polypropylene (Diapolymer N057
The same procedure as in Comparative Example 1 was carried out except that AG) was used to measure Izod impact strength and volume resistivity. The results are shown in Table 1.

Comparative Example 5 In Comparative Example 3, polypropylene (Diapolymer 480
0JG) instead of polypropylene (Diapolymer N057
The same procedure as in Comparative Example 3 was carried out except that (AG) was used to measure the Izod impact strength and volume resistivity. The results are shown in Table 1.

[0028]

[Table 1]

[0029]

The conductive powder composition of the present invention and the resin composition containing the same are mixed at a constant condition ratio with respect to the resin as described above to obtain about 10 ⁻¹ Ω · cm. It is possible to obtain an electrically conductive resin composition which is light in weight and has low electrical conductivity, excellent mechanical strength, and low specific gravity.

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Claims (5)

[Claims] 1. A conductive powder composition comprising 100 parts by weight of petroleum coke powder and 20 to 60 parts by weight of carbon black and 20 to 50 parts by weight of carbon fiber. 2. A conductive powder composition, wherein the petroleum coke powder according to claim 1 has an average particle diameter of 1 to 200 μm. 3. The carbon black according to claim 1, which has a dibutyl terephthalate oil absorption of 100 to 20.
A conductive powder composition characterized by using 0 ml / 100 g. 4. The carbon fiber according to claim 1,
A conductive powder composition comprising a short fiber having a fiber length of 1 mm or less. 5. The conductive powder composition according to claim 1 to 50 parts by weight per 100 parts by weight of a thermoplastic resin.
A conductive resin composition characterized by being mixed in an amount of 50 parts by weight.