| 摘要 |
Dies are disclosed for forming sheet-like extrudate of fluent material, such as a film of thermoplastic or solvent-plasticized material, or a liquid coating, e.g. a photographic coating, on a continuous support web. The dies include inner and outer cavities with the fluent material being supplied to the center or an end of the inner cavity. Between the inner and outer cavities there is an inner slot and between the outer cavity and the exterior of the die there is an outer slot. The inner cavity is open at one end, if end fed, or at both ends, if center fed. The open end, or each open end, is closed by closing means which are detachable for allowing access to the inner cavity for cleaning and inspection. A member is located in the cavity extending from the open end or each open end. The member serves to reduce the effective flow path for fluent material in the inner cavity. By appropriate selection of the shape of the member, uniform flow rates of fluent material through portions of the inner slot adjacent the member may be achieved. By providing a plurality of interchangeable differently shaped members, a plurality of different combinations of rheologies and flow rates of fluent material may be extruded while maintaining uniformity of widthwise thickness uniformity of the extrudate. The invention is also applicable in embodiments in which there is only a single cavity and a single slot. |
