Production method for conductive composite material
In a production method for a conductive composite material for an extruder that continuously discharges a kneaded product produced by kneading a raw material using a screw, the screw has a the screw body, the raw material transported along an outer circumferential surface of the screw body receives increased pressure by a barrier part in a transport part and is introduced to a passage from an inlet, and while the kneaded product is continuously discharged, the raw material transported along the outer circumferential surface of the screw body flows in the passage of the extruder and then is guided to the transport part via an outlet provided in the screw body, the raw material contains a conductive filler and a thermoplastic elastomer.
1. A production method for a conductive composite material, comprising:
a preliminarily kneading step for kneading and melting a raw material containing a conductive filler and a thermoplastic elastomer;
a dispensing step for repeatedly applying a shearing action and an extension action to the raw material while rotating a screw body of a single-screw extruder and transporting the raw materials in a melted state from a proximal end to a tip of the single-screw extruder; and
a discharging step for continuously discharging a conductive composite material from the tip of the single-screw extruder,
wherein in the dispensing step,
the shearing action caused by a difference in speeds of a flight of the screw body swirling along a transport path and an inner circumferential surface of a cylinder part of a barrel for housing the screw body is applied to the raw material, and
the extension action is applied to the raw material by passing the raw material through a passage which is provided inside the screw body and has an inlet and an outlet opened on an outer circumferential surface of the screw body.
2. The production method for a conductive composite material according to claim 1 , wherein
in the dispensing step, a transportation of the raw material is limited by a barrier part provided between the inlet and the outlet, a raw material reservoir in which a filling proportion of the raw material is 100% is formed, a pressure of the raw material is increased, and the raw material in the melted state in the raw material reservoir is flowed into the inlet.
3. The production method for a conductive composite material according to claim 1 , wherein
in the dispensing step, a rotational speed of the screw body is 200 rpm to 600 rpm.
4. The production method for a conductive composite material according to claim 3 , wherein
in the dispensing step, the number of times of applying the shearing action and the extension action to the raw material is from 4 times to 10 times.
5. The production method for a conductive composite material according to claim 1 , wherein
the inlet, the outlet, and the passage are holes having a circular cross-sectional shape, and an inner diameter of the holes is 2 mm or greater and smaller than 8 mm.
6. The production method for a conductive composite material according to claim 1 , wherein
wherein the conductive filler is carbon nanotubes and/or carbon black, and
wherein the thermoplastic elastomer is a hydrogenated styrene butadiene-based thermoplastic elastomer.
7. The production method for a conductive composite material according to claim 6 ,
wherein a content of the carbon nanotubes in the conductive composite material is 0.1 to 30 weight %.