JPH01104658A - Electrically conductive thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition achieving high electrical conductivity with low carbon fiber content, having excellent mechanical properties and suit able for elimination of static charge and antistatic treatment, etc., by compounding a specific amount of a specific inorganic compound. CONSTITUTION:The objective composition is produced by compounding 100pts. wt. of a mixture composed of (A) 40-95wt.% of a thermoplastic resin (e.g. crystalline polyethylene or polypropylene) and (B) 5-60wt.% of carbon fiber (e.g. polyacrylonitrile-based carbon fiber) with (C) 0.01-10pts.wt., preferably 0.1-5pts.wt. of one or more inorganic compounds having a volume-average diameter of <=0.1mm and selected from zinc sulfate, calcium sulfate, calcium carbonate, beryllium sulfate, etc.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a conductive thermoplastic resin composition containing carbon fibers, which exhibits excellent electrical conductivity, especially with a small content of carbon fibers, and at the same time has excellent mechanical properties. The present invention relates to a conductive thermoplastic resin composition that is excellent in terms of performance and exhibits high strength.

This composition is useful for removing static electricity, preventing static electricity, shielding electromagnetic waves, etc.

[Conventional technology]

It is known to obtain highly conductive thermoplastic resin compositions by blending carbon fibers with various thermoplastic resins (for example, JP-A-59-189142).

It is also known to improve conductivity by blending inorganic/organic phosphorus compounds with various thermoplastic resins (for example, Japanese Patent Laid-Open No. 58-215448).

[Problem that the invention seeks to solve]

However, in the former method, the desired high conductivity cannot be obtained unless a large amount of carbon fiber is contained. and,
When the amount of carbon fiber filled is large (when the carbon fiber is mixed into a thermoplastic resin using an extruder, becomes more,
This may result in poor biting into the extruder, ■ Melt-kneading may become uneven, resulting in poor kneading properties, or ■ Frequent breakage of extruded strands, resulting in poor processability of the resulting conductive resin composition. Become. Furthermore, in the molding process,
When the carbon fiber filling amount increases, the friction of the screw, barrel, etc. of the molding machine increases, which makes the molding process complicated and difficult. In addition, the resulting molded product also has a rough surface due to poor melt flowability of the resin, and physical properties such as tensile strength and bending strength are reduced.

In the latter method of blending a phosphorus compound, although the effect of improving conductivity can be obtained, the effect is small and furthermore, the mechanical properties of the blended composition are deteriorated.

[Means for solving problems]

Therefore, an object of the present invention is to provide a thermoplastic resin composition that has high electrical conductivity with a small amount of carbon fiber blended.

In view of the above, as a result of intensive research, the present inventors were able to achieve the above object by blending a specific inorganic compound, and came to accomplish the present invention.

That is, in the present invention, for a mixture consisting of 40 to 95% by weight of thermoplastic resin and 5 to 60% by weight of carbon fiber, 1
0.01 to 10 parts by weight of one or more inorganic compounds selected from calcium sulfate, zinc sulfate, calcium carbonate, beryllium sulfate, and zinc stearate. The present invention relates to a conductive thermoplastic resin composition.

The present invention will be explained in detail below.

Examples of the thermoplastic resin in the present invention include polyvinyl chloride, polyethylene, polypropylene, polystyrene, ABS, polyacecool, polyurethane, polyamide, polyester, poly(meth)acrylate, polyester elastomer, polycarbonate, modified polyphenylene oxide, polyphenylene sulfide, and polyphenylene sulfide. Examples include etherketone, polyetherketone, polyetherimide, polysulfone, etc., and these may be used alone or as a blend of two or more thereof. Among these, crystalline polyethylene, polypropylene, polyamide, polyester, etc. are particularly preferred. Particularly suitable polyamides are nylon 6 and nylon 66, and polyesters are polyethylene terephthalate or modified copolymers thereof.

The carbon fibers used in the present invention include all known carbon fibers including polyacrylonitrile carbon fibers, pitch carbon fibers, vapor grown carbon fibers, and the like. Its form may be chopped strand, milled fiber, or the like.

In addition, the surface of carbon fiber is coated with resin to increase its affinity with resin.
There is no problem even if the size is made of resin such as epoxy, urethane, nylon, or polyether.

The content of carbon fiber is 5 to 60% by weight, preferably 7 to 60% by weight.
It is 35ffi amount%. If the content is 5% by weight without grooves, the conductivity is too low, and if it exceeds 60% by weight, the fluidity during molding will deteriorate and the processability will be significantly impaired, which is not preferable.

The specific inorganic compound used in the present invention is selected from calcium sulfate, zinc sulfate, calcium carbonate, beryllium sulfate, and zinc stearate, and its shape is preferably 0.1 ma+ or less in volume average diameter. ,0.1f
filI+ or less is more preferable.

Although the mechanism of action of the blending of these specific inorganic compounds is not clear, it has the effect of significantly improving the electrical conductivity of the carbon fiber-containing thermoplastic resin.

These specific inorganic compounds are based on a mixture consisting of 40 to 95% by weight of thermoplastic resin and 5 to 60% by weight of carbon fiber.
It is blended in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight of the mixture. If less than 0.01 parts by weight is added, no effect of improving conductivity will be observed, and if it exceeds 10 parts by weight, the processing stability during extrusion of the resin composition will deteriorate or problems may occur in tensile strength, bending strength, etc. arise.

The conductive thermoplastic resin composition of the present invention is produced by mixing a thermoplastic resin in various shapes such as powder, beads, and pellets, carbon fibers, and the above-mentioned specific inorganic compound in a Banbury mixer.
It is obtained by mixing and kneading in a kneader or extruder such as a co-kneader, single-screw extruder, or twin-screw extruder.

In order to make the composition of the present invention uniform, a crosstalk machine,
Before mixing and kneading in the extruder, preliminary mixing may be performed using a means such as a tumbler-1 high-speed mixer.

The resin composition obtained by performing this mixing and kneading is supplied into the hopper of an injection molding machine, melted in a plasticizing millinder, injected into an injection mold, and cooled and solidified in the mold to form a molded product. By taking out, an injection molded article using the resin composition of the present invention can be obtained. Similarly, an extrusion molded product using the resin composition of the present invention can be produced by supplying the resin composition into the hopper of an extrusion molding machine, melting it in the plasticizing cylinder, and extruding it through a goo installed at the tip of the extruder. Obtainable.

〔Example〕

Next, examples and comparative examples will be shown.

The thermoplastic resin, carbon fiber, and inorganic compound used in these examples are shown below.

■Thermoplastic resin polybutylene lentil thalay) (PBT) (EPL side,
Product name: Barox 310-5EO) Polycarbonate CPC> (EPL @, Product name Nilexan 141-111) Nylon-66 (N-66) [Asahi Kasei ■, Product name: Leona 1300) Carbon fiber [Asahi Nippon Carbon■, Product name: Carboron A-6000
) ■Inorganic compounds Calcium sulfate (CaSO4・2%0) Zinc sulfate (Zn
SO4・7H2o) Beryllium sulfate (BeS04・,1) 12o:1 Zinc stearate (Zn (C,,11,,0! >@ ) Callasim carbonate (CaCO3) Examples 1 to 10 Comparative examples 1 to 9 Table 1 A predetermined amount of carbon fiber and an inorganic compound are triblended into the thermoplastic resin described in
6+nmφ, L/D-30) to create a pellet.

Next, the obtained pellet was molded into a screw injection molding machine (3
oz.) to form a test piece, and its surface resistance, tensile strength, and bending strength were measured.

The results are shown in Table 1.

[Margin below]

As is clear from Table 1, the resin composition of the present invention has far superior conductivity compared to a thermoplastic resin simply reinforced with carbon fibers, and therefore It is possible to reduce the amount of fiber, and at the same time has excellent mechanical strength.

Moreover, in the composition containing the phosphorus compound of the comparative example, although some effect of improving conductivity can be obtained, the mechanical properties are deteriorated.

〔Effect of the invention〕

The conductive thermoplastic resin composition of the present invention has excellent conductivity with a small carbon fiber content and excellent mechanical properties.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] (1) Thermoplastic resin 40-95% by weight and carbon fiber 5-6%
0.01 to 10 parts by weight of one or more selected from calcium sulfate, zinc sulfate, calcium carbonate, beryllium sulfate, and zinc stearate per 100 parts by weight of the mixture. A conductive thermoplastic resin composition comprising an inorganic compound.