Patent ID: 8434498

Claim:
A method of preparing cellulose acetate or polyolefin fibers suitable for use in a fibrous tow filter material, the method comprising: (a) providing a cellulose acetate or polyolefin polymer material in the form of a fiber precursor solution comprising the cellulose acetate or polyolefin polymer material dissolved in a solvent; (b) adding a starch material to the polymer material to form a modified polymer material, wherein the starch material is insoluble in the solvent of the fiber precursor solution and selected from the group consisting of (i) a starch ester formed by reaction between natural starch and one or more aliphatic C2-24 carboxylic acids or reactive derivatives thereof, and having a degree of substitution of 0.5 to 3; (ii) a hydroxyalkylated starch or ester thereof; (iii) an oxidized starch; (iv) a crosslinked starch; (v) a grafted starch; (vi) a transglycosylated starch; (vii) a plasticized starch; (viii) a starch ether; and a mixture thereof; (c) extruding the modified polymer material through a spinerette to produce cellulose acetate or polyolefin fibers; (d) solidifying the fibers following extrusion; and (e) collecting the solidified fibers, the fibers comprising the starch material imbedded therein.