JPH0741609A - Electrically conductive resin composition - Google Patents

Abstract

PURPOSE:To provide a lightweight, inexpensive resin composition having high electrical conductivity, incorporated with a highly corrosion-resistant, electrical conductivity-imparting carbonaceous filler. CONSTITUTION:This resin composition comprises (A) a noncrystalline polyolefin as synthetic resin and (B) an electrical conductivity-imparting carbonaceous filler.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a conductive resin composition having high conductivity, which is useful for radio wave shields, various contacts, electrochemical reaction electrodes, sheet heating elements, etc. and has an antistatic effect. It is about.

[0002]

2. Description of the Related Art Conventionally, as a conductive resin composition, a synthetic resin in which a metal- or carbon-based conductivity-imparting filler is dispersed is known. As its application, corrosion resistance is required, and with a conductivity-imparting filler of the carbon-based to what volume resistivity may be relatively high resistance more than about ^{10 2 Ω · cm, 10 0} Ω · cm or less, further For those requiring a high conductivity of 10 ^-2 Ω · cm or less, a metal-conducting filler such as gold, silver, copper, palladium or aluminum was used. As synthetic resins used for these, thermoplastic resins such as crystalline polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polycarbonate, polyphenylene sulfide, thermosetting resins such as epoxy resin and urethane resin have been used. .
However, the conventional conductive resin has a limit of about 60 parts by volume with respect to 100 parts by volume of the synthetic resin, and therefore, when the carbon-based conductivity-imparting filler is used, resistance value was limited to about 10 ⁰ Ω · cm. When a metal-made conductivity-imparting filler is used, conductivity of 10 ^-2 Ω · cm or less can be obtained,
For applications requiring corrosion resistance, it is necessary to use a noble metal such as gold, platinum, palladium, etc., which are very expensive and heavy.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems by using a carbon-based conductivity-imparting filler having good corrosion resistance and having a resistance of 10 ^-2 Ω · cm or less. An object of the present invention is to provide a lightweight and inexpensive conductive resin composition having high conductivity.

[0004]

DISCLOSURE OF THE INVENTION As a result of various studies on the types and properties of synthetic resins, the inventors have paid attention to the fact that the dispersibility of the conductivity-imparting filler in the synthetic resin is largely due to the properties of the synthetic resin. The present invention has been completed. That is, the present invention is a conductive resin composition comprising a synthetic resin and a carbon-based conductivity-imparting filler, wherein the synthetic resin is an amorphous polyolefin.

The present invention will be described in detail below. Amorphous polyolefin is used as the synthetic resin in the conductive resin composition of the present invention. Normally, the molecular structure of polyolefins such as polyethylene, polypropylene and polybutene is isotactic and crystalline.
The polyolefin used in the present invention is required to be amorphous having an atactic structure. Examples thereof include polypropylene alone, polypropylene and polyethylene, or copolymers of polybutene, and various polymers having different degrees of polymerization are adopted. However, only one of them may be used, or two or more of them may be blended. . As the degree of polymerization,
It is preferably 10,000 or less, preferably 1000 to 8000, and more preferably 1500 to 3000.

The melt viscosity of these amorphous polyolefins is preferably about several poises to several hundred poises at 190 ° C., which is 1 in comparison with that of crystalline polyolefins.
The value is as low as 0 to 1/1000. In addition, this product has no polarity and has an interfacial tension similar to that of the carbon-based conductivity-imparting filler. From these properties, the carbon-type conductivity-imparting filler is added to 100 parts by volume of the amorphous polyolefin. It is possible to add up to about 600 parts by volume.

As the carbon-based conductivity-imparting filler, graphite powder such as flake natural graphite, amorphous natural graphite, expanded graphite and artificial graphite, carbon black such as acetylene black, ketjen black, and conductive oil furnace black are used alone or in combination. Examples include blends. According to the results of studies by the inventors, blending graphite and carbon black in an appropriate ratio can achieve a lower volume resistivity when filled in a resin matrix. That is, by setting the compounding ratio of graphite to carbon black in the range of 1: 1 to 5: 1, preferably 2: 1 to 4: 1, high conductivity can be obtained with a small filling amount. This is because the mutual connection of particles is insufficient only with graphite (particle size of about 0.1 to 10 μm), but due to the presence of fine carbon black particles (1 to several 10 nm) between the graphite particles,
This is probably because conduction between graphite particles becomes possible. In this case, the carbon-based conductivity-imparting filler is 600
It is possible to fill up to about the volume part, but if the filling amount is too small, the desired resistance value cannot be obtained, and if it is too large, the physical strength of the product becomes weak, so 100 parts per 100 parts by volume of the synthetic resin. ~ 500 parts by volume, preferably 100-300
It is desirable to use the capacity part.

The form of the olefin used in the present invention is
Since powdery or sheet-shaped powder causes blocking, it is preferable to use lump-shaped ones commonly called “potato”. For this reason,
As a method for dispersing and kneading the carbon-based conductivity imparting filler in this, a method of adding the carbon-based conductivity imparting filler into the amorphous polyolefin while stirring the molten polyolefin, and the carbon-based conductivity-imparting filler While stirring the property-imparting filler, the amorphous polyolefin in a molten state is sprayed and dispersed, and then kneaded by using a Banbury mixer, a pressure kneader, a two-mixing roll, or the like. As a property imparting filler, oil absorption is 100
When a high value of 100 ml / 100 g or more, particularly 500 ml / 100 g or more is used, a uniform dispersion state can be obtained by adopting the latter method.

The conductive resin composition of the present invention contains various additives such as crystalline polyolefin, reinforcing agents such as SBS and SEBS, heat stabilizers, light stabilizers and antiaging agents.
It may be added in an amount of not more than 1% by weight, preferably 1 to 8% by weight. This is because in the range of more than 10% by weight, the property of the amorphous polyolefin capable of being filled with high filler may be impaired.

[0010]

As described above, in the present invention, since the amorphous polyolefin is used as the synthetic resin, it becomes possible to fill the carbon-based conductivity-imparting filler at a very high ratio, and to obtain high conductivity. You can Furthermore, since the carbon-based filler is used as the conductivity-imparting filler, it is possible to obtain a cheap and lightweight conductive resin composition having excellent corrosion resistance.

[0011]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention.

[Example] Amorphous polypropylene "UT2"
115 "[trade name of Ube Lexen Co., Ltd.] (true density of 0.
86 g / cm ³ ) 100 parts by weight in a molten state at 190 ° C., and while stirring with a kneader, flake natural graphite “CP
B over 30 "[Corporation Chuetsu Graphite Industries, Ltd., trade name] (true density 2.2 g / cm ³⁾ 300 parts by weight of carbon black" ass thien Black ^R EC "[Lion Corporation, trade name] ( 100 parts by weight of true density of 1.9 g / cm ³ ) was added, dispersed and kneaded to obtain a conductive resin composition of the present invention. When the filling ratio of the conductivity-imparting filler at this time is converted into a volume part, it is 188 volume parts with respect to 100 volume parts of the synthetic resin. Using this conductive resin composition as a raw material, press molding (170 ° C., 70 kgf / cm ² , 10 minutes) was performed to obtain a molded product having a thickness of 0.5 mm and a size of 300 × 300 mm. The volume resistivity of this molded body is calculated by Loresta AP / MCP
It was 8.7 × 10 ⁻³ Ω · cm when measured using a T-400 (trade name, manufactured by Mitsubishi Petrochemical Co., Ltd.). Also,
The density was 1.7 g / cm ³ . [Comparative Example] 100 parts by weight of crystalline polypropylene J130G [trade name of Ube Industries, Ltd.] (true density of 0.90) was added to flake natural graphite (the same as Example 1) and carbon black (Example 1). The same) (3: 1 mixture) was added and kneaded using a pressure kneader at 220 ° C., but the limit was 120 parts by weight. When the filling ratio of the conductivity-imparting filler at this time is converted into a volume part, it is 50.9 volume parts with respect to 100 volume parts of the synthetic resin. This was press-molded to obtain a molded body similar to that of Example 1, and the volume resistivity was measured and found to be 1.2 × 10 ⁰ Ω · cm.

[0013]

As is clear from the examples, according to the present invention, a conductive resin composition having high conductivity is provided by using a carbon-based conductivity-imparting filler which is excellent in corrosion resistance, inexpensive and lightweight. By using this, it is possible to achieve weight reduction and cost reduction, and to obtain long-term environmental resistance reliability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiro Ohara 1-406-1 Yoshino-cho, Omiya-shi, Saitama 1 Shin-Etsu Polymer-Tokyo Factory

Claims (1)

[Claims] 1. A conductive resin composition comprising a synthetic resin and a carbon-based conductivity-imparting filler, wherein the synthetic resin is an amorphous polyolefin.