| 摘要 |
PURPOSE:To obtain a highly expanded resin plate with good surface condition without any wrinkle by a method in which a thermoplastic resin containing a blowing agent is extruded into a tubular form through a mouth piece, directed into a frame of a specific shape, expanded there, and then clamped between rolls. CONSTITUTION:A thermoplastic resin containing a blowing agent is melted and extruded into a tubular form through a mouth piece 22, and then passed along the inner wall of a frame 3 whose mouth piece side portion 31 is provided with a funneled inner cavity expanding toward its tip in its inside and whose roll side portion 32 is also provided with an inner cavity of a practically similar cross section in its inside. The tube coming from the frame 3 is flattened and put between paired rolls 4 in such a way that the inner surfaces of the tube while they are still in unhardened state are bonded with each other to form an expanded plate. In this case, compressed air is fed into the tube a from a pipe 24 to increase forcibly the inner diameter of the tube a until it is closely contacted with the inner wall of the frame 3. |
