Patent GB-757841-A (GB)
Title: A method of preparing filter rod and filter rod when prepared by the method
Inventor: MAUTHNER ERIC GEORGE HERBERT
IPC: B01D39/14
Filed: 1954-07-02
Abstract: 757,841. Tobacco smoke filters. CIGARETTE COMPONENTS, Ltd. June 20, 1955 [July 2, 1954], No. 19528/54. Class 130. [Also in Group IX] Filter rods are formed by dispersing fibres in air and depositing them on to a conveyer to form a uniform band of fibres, gathering and compacting the band into a rod of fibres, and binding together at least the outermost fibres of the rod with a binding medium. In Fig. 2 wood pulp fibres are fed to a weighing machine 10, discharged at a controlled rate on to a conveyer 11, passed through a device 12 including spike rollers which break up any lumps of fibre, and discharged into a dispersing device 13, such as a disintegrating mill, from which the fibres are blown into a passage 16 in which the fibres become deposited in a uniform band upon a conveyer 17, a suction device 18 at the end of passage 16 assisting the deposition of the fibres. The band of fibres is carried forward and gathered and compacted into rod shape by two conveyer bands 19 and a shaping roller 20, the rod being carried by a tape 21 through a garniture 22 to reduce it to the required diameter and by a tape 23 beneath a spraying device 25 or coating roller which impregnates or coats the rod with a liquid binding medium such as a solution of cellulose acetate in methyl-ethyl ketone. The coated or impregnated rod is pulled through a second garniture 26 and shaping rolls 27 and then passed through a drying tunnel 28 in which the binding medium is dried by, for example, hot air, infra-red, or induction heating. The dried rod, which may be wrapped in a wrapper or left unwrapped, is cut by knife 29 into separate lengths which are. subsequently incorporated in cigarettes or used for cigarette holders or other smokers' appliances. Other binding materials which may be used are glues, alkyl celluloses, cellulose esters or ethers or synthetic resins. In a modification, Fig. 3, the air dispersed fibres are blown into a container 37 and deposited on a wire mesh conveyer or drum 38 on the rear face of which a vacuum is maintained, the band of fibres on the conveyer 38 being carried downwards and deposited on a second conveyer 40 on which the fibres are gathered into rod shape after the addition there - to of a binding medium in powdered or filament form by a shaking conveyer 50. Alternatively a binding medium in filament form may be added to the fibrous mass in the chamber 37 by a dispersing device 52. The rod is wrapped in a paper wrapper in a garniture 46, cut into sections by a knife 54, and passed through a heater 55 which heats the sections to a temperature at which the binding medium exerts its binding action. Other fibres which may be used for the filter are cotton, hemp, jute, flax, sisal, manila, wool, hair, mineral fibres such as glass or asbestos, and fibres of regenerated cellulose materials. The. filtering action of the filter may be modified by the addition to the fibres of materials such as powdered clay, diatomaceous earth, ion exchange materials; carboxylic acids, femic chloride, manganese dioxide, cobalt oxide, potassium bitartrate, magnesium oxide, sodium bisulphate, sodium bisulphite, charcoal, abumina, and silica gel.