JPS5846508A - Conductive material and method of producing same - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive material made of a thermoplastic synthetic resin and a conductive fiber. The present invention relates to a conductive material in which continuous conductive fibers S---〇〇 parts by weight are almost uniformly dispersed therein, and a method for producing the same.

Organic polymer materials, represented by thermoplastic synthetic resins, generally belong to advanced electrical insulators with a volume resistivity of about 10 to 10Ω・α, and are widely used in fields such as wire sheaths and electrical parts that take advantage of this property. has been done. However, recently, with the diversification of market demands, the resistivity of thermoplastic synthetic resins has been lowered and so-called conductive polymer materials (this name means that they have considerable electrical conductivity, and are not necessarily similar to metals). Applications have been developed and already have a significant market.

Currently, the most popular method for imparting conductivity to thermoplastic synthetic resins is to knead carbon black into the resin. Even with complicated materials/
The limit is around α.

Furthermore, the mechanical strength of resin materials containing such non-reinforcing fillers deteriorates, resulting in a significant decrease in commercial value. On the other hand, recently, products made by kneading carbon fiber into thermoplastic synthetic resin (mainly polypropylene) have begun to be commercially available, but this material also has a volume resistivity of /cPΩ. α or more, and its conductivity is not satisfactory.

The present invention solves the above problems and has excellent mechanical strength.
The present invention also provides a conductive material made of a thermoplastic synthetic resin having sufficient conductivity, and an industrially advantageous manufacturing method thereof. That is, an object of the present invention is to provide a conductive material manufactured by mixing thermoplastic synthetic resin powder while opening conductive fibers and molding the mixture, and a method for manufacturing the same. It is.

Thermoplastic synthetic resins used in the present invention include low density polyethylene, medium density polyethylene, high density polyethylene,
Polypropylene, polybutene to polymethylpentene
Polyolefin resins such as /, polyvinyl chloride resins, polystyrene resins, acrylic resins such as polymethyl methacrylate, polyamide resins such as 6-nylon and 6-nylon, polyester resins such as polyethylene terephthalate and polybutylene terephthalate. resin,
Examples include polycarbonate resin, polyacetal resin, and fluorine resin. Furthermore, the present resin also includes copolymers of the above resins, modified products with rubber and fillers, and the like.

In the present invention, these thermoplastic 4 synthetic resins are most preferably used in the form of powder, and the particle size is 500.
It is preferably 300 microns or less, particularly 300 microns or less.

When the amount of powder with a particle size of SOO microns or more increases, uniform mixing with the conductive fibers becomes difficult. These thermoplastic synthetic resin powders are used by mechanically pulverizing general pellet-like, bead-like products, or waste materials from molded products, but it is economical to use powder obtained during synthetic resin manufacturing. Most advantageous.

Although there are no particular limitations on the conductive fibers used in the present invention,
Currently available materials include carbon fiber (including graphite fiber);
Examples include glass fiber coated with metal such as aluminum, metal fiber (eg, aluminum fiber), and the like. These are generally commercially available as products made by bundling dozens to hundreds of single fibers such as roving, toku, or chopped strands cut to a certain length, and in the present invention, these are used as materials. It is possible. However, there are two conditions for the conductive fibers used in the present invention.

The first condition is that the above-mentioned material is not used in a bundled state, but is dispersed in an opened state in a thermoplastic synthetic resin. However, opening here refers to a state in which the fibers are loosened from the bundle by external force.

The first condition is that the length of the conductive fiber is equal to or greater than O.SW. As mentioned above, products in which conductive fibers are spread and dispersed in thermoplastic synthetic resin are already on the market, and these products are made by kneading and dispersing carbon ring wire into resin. In this product, during the process of kneading the fibers into the resin, most of the fibers are cut to lengths of less than O1S■, and the original strength and conductivity of carbon fiber cannot be demonstrated (
Become.

In zero-start W14, opened fibers with an average length of 03 m or more are dispersed in a thermoplastic synthetic resin, resulting in a product with very good mechanical strength and electrical conductivity. especially,
In the present invention, it is preferable to use chopped strands having a length of θS or more as the conductive fiber material.

In carrying out the present invention, it is most preferable to use chopped struts as the conductive fibers and to use the thermoplastic synthetic resin in the form of powder. There are various methods for uniformly dispersing opened conductive fibers into thermoplastic resin powder, but one preferred example is to mix the two in a mixer with rotary blades at the bottom, and then heat and pressurize the mixture. This is a method of molding.

To explain in more detail, chopped strands such as carbon fiber and thermoplastic synthetic resin powder are charged into a Henschel type mixer, which is a typical example of a mixer with rotary blades at the bottom.1. ．． At a rotation speed of about 200 to 2000 rpm
Ii rotation to gradually open the carbon fibers, and at the same time, the resin powder is encapsulated in the opened fibers to form a uniform mixture. At this time, the same result can be obtained even if the entire amount of the thermoplastic synthetic resin is first charged into the container and the chopped strands are gradually added thereto.

Next, to mold this mixture, it is heated and pressed at a temperature higher than the melting (softening) point of the thermoplastic synthetic resin to form it into a shape such as a sheet. In the case of batch type, it is possible to use a general-purpose heating press machine, but in the case of continuous type, which has good productivity, the mixture is first formed into a continuous mat shape using a fleece former such as a batting machine, and then Heat and press with a 4M pressure machine such as a double belt press. This double belt press is well known from Sandvik Conveyor Systems. In addition, after forming into a sheet, preheating to above the melting (softening) point of the thermoplastic synthetic resin and press forming (stamping) using a matte metal die etc. can be used to post-process products into complex shapes. It is also possible.

The molded product obtained by the heating and pressing method of the present invention has almost no breakage of the conductive fibers compared to molded products obtained by extrusion or injection methods after kneading conventional conductive fibers and synthetic fibers. , has extremely excellent mechanical strength and electrical conductivity. As described above, since the conductive material according to the present invention has excellent properties, it can be used in antistatic containers (e.g., IC magazines), antistatic workbenches, antistatic tools, surface heating elements, electrode radio wave shields, etc. 1 case of board mata, material for electroplating,
It can be used for a wide range of purposes such as calculator keyboards.

The present invention will be specifically described below with reference to Examples.

Example: 700 parts by weight of polypropylene (product name: Mitsui Noprene JHH (G) J manufactured by Mitsui Toatsu Chemical Co., Ltd.) powder (particle size 300 tons or less) was added to the thermoplastic synthetic resin, and the average length of carbon fiber was added to the conductive fiber. Using the A7 weight part of Sa6 Kasumi's chopped straightener (trade name: ``Cureca C-/θATJ4'' manufactured by Kagaku Kogyo Co., Ltd.), mix it with a mixer with rotary blades at the bottom (product name: [Super Mixer 20LJ]). (manufactured by Seisakusho),
Number of revolutions! The mixture was stirred at r 00 rpm for 3 minutes to obtain a mixture in which the polypropylene powder was almost uniformly dispersed and adhered to the opened chopped strands.

Next, this mixture was piled up in a mat shape of approximately the same thickness in a metal frame with a thickness of 3.511 m, and the top and bottom of the mat was covered with a single pressing iron plate. After charging this into a 100 ton hydraulic press and preheating it to 220℃ for S minutes, it was heated at the same temperature for S minutes/0
Pressurize to a pressure of 0 k/V'cd G, then transfer this to another hydraulic press and pressurize to a pressure of / 00 Wd a, 33
Cooled for S minutes at °C. The obtained molded product is a polypropylene sheet in which long lengths of opened carbon fibers are almost uniformly dispersed, and its volume resistivity is 0. //Ω・It was a bacteria.

Example: The method was exactly the same as in Example except that chopped strands of carbon fiber with an average length of θ7 (trade name: ``Kureka M-107TJ'' manufactured by Kureha Chemical Industry Co., Ltd.) were used as the conductive fibers. A sheet was prepared.The obtained sheet was made of polypropylene in which opened carbon fibers having a length of 0.7 cm were almost uniformly dispersed, and its volume resistivity was 2Ω·min.

Comparative Example The same material as Example 1 was used as a raw material and kneaded in a pressure kneader at 90"C for S minutes.The resulting kneaded product was press-formed into a sheet in the same manner as in Example 1. .

The obtained sheet was a polypropylene sheet in which opened carbon fibers were uniformly dispersed, but the carbon fibers were cut to an average length of θjaws or less, and the volume resistivity was 6 sΩ・wounds. there were.

Reference Example: A commercially available conductive material (trade name: [Tonen CFRPP
A flat plate was obtained by injection molding J-/j (manufactured by J Tonen Petrochemical Co., Ltd.), and the volume resistivity of this flat plate was /0''Ω·1 or more.

Patent originator: Japan Petrochemical Co., Ltd.

Claims (1)

[Claims] +1) Spread discontinuous conductive fiber j-20 having an average length of θS■ or more based on 100 parts by weight of thermoplastic synthetic resin
A conductive material in which 0 parts by weight are substantially uniformly dispersed. (2) The conductive material according to claim 1, wherein the conductive fiber is carbon fiber. (3) The thick strands of conductive fibers and the thermoplastic synthetic resin powder are mixed with the thermoplastic synthetic resin powder bundle while opening the conductive fibers in a mixer with rotary blades at the bottom of the container. A method for producing a conductive material, which comprises heating and press-molding a mixture obtained by