| 摘要 |
PURPOSE:To manufacture the titled large-sized uniform tube having excellent heat resistance, and composed of the side wall having dense internal structure and excellent mechanical characteristics, by extruding an aromatic polyimide dope in a state covering a specific core material, and coagulating the tube by a specific method. CONSTITUTION:A polyimide dope obtained by dissolving (A) an aromatic polyimide containing the recurring unit of formula (R is a bivalent residue corresponding to an aromatic diamine excluding the amino groups) in (B) a solvent composed of a phenolic compound, is extruded in a state covering a core material havig higher thermal expansion coefficient than the component A (e.g. core material made of tetrafluoroethylene resin), and the outer surface of the covering dope layer is made to contact with (C) a coagulation liquid compatible with the component B to extract 5-70wt% of the component B in the covering dope liquid and obtain a coagulated covering layer having coagulated layer at the outer surface. The product is dried, solidified and separated from the core material to obtain the objective tube. EFFECT:Even a tube having irregular cross-section can be manufactured.
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