| 摘要 |
PURPOSE:To make better the skin of a rubber where the blended ratio of a natural rubber is low, by providing a pole-shaped projection at the center of the tip of a discharge part, arranging plural holes on a concentric circle and carrying out discharge. CONSTITUTION:A pole-shaped projection is provided at the center of a mouthpiece 2 where a plurality of holes 1 a rubber passes through are arranged in such a way that the centers of the holes are located on a concentric circle whose center substantially coincides with the center of the pole-shaped projection. A cylindrical shape, conical shape or combined shape of cylindrical and conical shapes can be applied as the shape of the pole-shaped projection. The flow of a molten thermoplastic substance at a discharge part of an extruder is changed by the existence of the pole-shaped projection at the center of the mouthpiece and the substance can be supplied to each hole of extrusion without any pressure deviation. It is thereby possible to obtain a good skin by extrusion. |
