Process for extruding plasticized open cell foamed cellulose acetate filters
AssigneeCelanese Corporation
InventorsCarl J. Howell, Jr., David W. Trott, Jesse L. Riley
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Abstract
A melt extrusion process for producing a low density open cell filtering element for an aerosol such as tobacco smoke from plasticized cellulose acetate. A mixture of cellulose acetate, plasticized, a volatile liquid blowing agent which is at least a partial solvent for the cellulose acetate and a nucleating agent are melt extruded under conditions wherein the melt is subjected to high shear, the loss of the blowing agent through back flow is prevented, the melt is reduced in temperature prior to extrusion and the extrudate is conditioned in a hot air chamber and then sized in a sizing die.
Claims11
A process for the preparation of a plasticized, open cell, foamed cellulose acetate filter rod, said process comprising melt extruding through an elliptical or circular orifice of a screw extruder a mixture of cellulose acetate, a nontoxic, taste compatible thermally stable plasticizer having a boiling point of not less than 180.degree. C., a blowing agent which is at least a partial solvent for cellulose acetate and a nucleating agent, said melt being substantially free of entrained air, and the extrusion pressure profile being such as to prevent said blowing agent from backing up in said screw extruder.
Dependencies are inferred from the claim text.