U.S. Patent 6,344,239. A method for producing a tobacco filter material which is either a coating process for coating the surface of a fibrous or particulate cellulose with a cellulose ester having an average substitution degree of about 2.0 to about 2.6 to give a coated cellulose, and wet webbing the coated cellulose into a sheet, or a treating process for treating a naturally occurring or regenerated cellulose fiber or particle with an organic acid and an organic acid anhydride or organic acid halide in a liquid phase to give a cellulose derivative.