| 摘要 |
Tubular sheet material is produced by extruding a fluid polymer material through a hollow center die having an annularly extending extrusion orifice exit rotated about the die axis to form a continuous or discontinuous annular-form structure which is collected on a supported surface advancing through the hollow center of said die which surface at least in the zone of collection has a generally cylindrical shape concentric with the axis of die rotation. The collected structure undergoes attenuation because of the die exit rotation and, consequently, has a grain therein extending at an angle, e.g. helically, to the general extrusion direction. The collected structure may after solidification be slit and opened into sheet form or separated into filaments. The collecting surface may be formed by plural endless belts passing through said die center and arranged and supported from beneath so as to collectively define a cylindrical shape or by a solid toroidal shaped member having the toroidal axis extending through the die center. The fluid polymer material may contain up to relatively high amounts of staple fibers.
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