Cellulose ester fibrillar structure
AssigneeCelanese Corporation
InventorCharles Herbert Keith
Life of this patent
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Abstract
Cellulose ester fibrillar material is produced by forming a cellulose ester dope, pumping the dope to an extrusion orifice, extruding the dope through the orifice into a region of shear and high draw in a precipitation bath containing a non-solvent for said cellulose ester maintained at an elevated temperature. The fibrillar material is preferably subjected to further treatment to reduce the particle size and set the structure by expanding voids and expelling residual solvent. Paper having a high degree of opacity is produced by incorporating the cellulose ester material to obtain light weight paper.
Claims5
An apparatus for the production of an opaque, voidy fibrillar structure which comprises a precipitation tank containing a precipitation bath;
- a substantially cylindrical disk positioned within said tank and submerged in said bath;
- means for rotating said disk in said bath at a peripheral speed of at least 500 meters per minute;
- a stationary annular wall spaced from said disc's peripheral surface by 1/16 to 1/2 inch;
- one or more orifices positioned about the periphery of said disk;
- means for pumping additional precipitation bath into said precipitation bath and past the periphery of said disk at a flow rate of at least 0.5 liter per minute per extrusion orifice;
- means for removing the precipitated fibrillar structure from said bath;
- and means for homogenizing said fibrillar structure.
Dependencies are inferred from the claim text.