Patent GB-1081520-A (GB)
Title: Carbon filter material and a method of preparing it
IPC: C01B32/384
Filed: 1965-12-22
Abstract: A filtering material, for gases or liquids and particularly for a cigarette filter tip, consists of free flowing particles of 0.1 to 25 mm. diameter, each comprising a homogenous mixture of 5 to 95% of cellulose crystallite aggregates and/or cellulose crystallite aggregate derivatives having a particle size of 0.1 to 375 microns and 95 to 5% of carbon of particle size 1 to 65 microns.  The crystallite aggregates are prepared by hydrolysis of cellulose in which the acid-soluble amorphous portion is washed out as in Specifications 874,945, 970,111 and 970,112.  The derivatives involve chemical substitutions in the cellulose crystallite, either before or after disintegration to the required size, as in Specification 976,335. The carbon and cellulose or derivative are mixed with 100 to 200% aqueous liquid and formed into spherical particles in a ball mill or rotary pan, as the liquid evaporates.  The liquid may be water or water mixed with organic liquids such as benzene and isopropyl alcohol.  The carbon may be activated before or after formation into the spheres.  The spheres may be flavoured by tobacco extract in the formation liquid or in a subsequent impregnation, for use in a cigarette filter.ALSO:A filtering material, for gases or liquids and particularly for a cigarette filter tip, consists of free flowing particles of 0.1 to 25mm. diameter, each comprising a homogeneous mixture of 5 to 95% of cellulose crystallite aggregates and/or cellulose crystallite aggregate derivatives having a particle size of 0.1 to 375 microns and 95 to 5% of carbon of particle size 1 to 65 microns.  The crystallite aggregates are prepared by hydrolysis of cellulose in which the acid-soluble amorphous portion is washed out as in Specifications 874,945, 970,111 and 970,112.  The derivatives involve chemical substitutions in the cellulose crystallite, either before or after disintegration to the required size, as in Specification 976,335.  The carbon and cellulose or derivative are mixed with 100 to 200% aqueous liquid and formed into spherical particles in a ball mill or rotary pan, as the liquid evaporates.  The liquid may be water or water mixed with organic liquids such as benzene and isopropyl alcohol.  The carbon may be activated before or after formation into the spheres.  The spheres may be flavoured by tobacco extract in the formation liquid or in a subsequent impregnation, for use in a cigarette filter.ALSO:A filtering material, for gases or liquids and particularly for a cigarette filter tip, consists of free flowing particles of 0.1 to 25 mm. diameter, each comprising a homogeneous mixture of 5 to 95% of cellulose crystallite aggregates and/or cellulose crystallite aggregate derivatives having a particle size of 0.1 to 375 microns and 95 to 5% of carbon of particle size 1 to 65 microns.  The crystallite aggregates are prepared by hydrolysis of cellulose in which the acid-soluble amorphous portion is washed out as in Specifications 874,945, 970,111 and 970,112.  The derivatives involve chemical substitutions in the cellulose crystallite, either before or after disintegration to the required size, as in Specification 976,335.  The carbon and cellulose or derivative are mixed with 100 to 200% aqueous liquid and formed into spherical particles in a ball mill or rotary pan, as the liquid evaporates.  The liquid may be water or water mixed with organic liquids such as benzene and isopropyl alcohol.  The carbon may be activated before or after formation into the spheres.  The spheres may be flavoured by tobacco extract in the formation liquid or in a subsequent impregnation, for use in a cigarette filter.