Patent GB-906424-A (GB)
Title: Improvements in or relating to tobacco smoke filter elements
IPC: A24D3/14
Filed: 1958-12-05
Abstract: Tobacco smoke filtering element manufacture includes the steps of spreading out a plurality of filaments, melting a wax or waxy material having a melting point above 35 DEG C. and spraying it on the filaments in a particle size of less than 30 microns (e.g. down to 0.5 micron) to form nodes and ridges thereon.  The filaments may comprise a tow of at least 10,000 continuous crimped cellulose acetate filaments of from less than 3 to 16 individual denier and 20,000 to 100,000 total denier and the waxy material be a high-molecular-weight compound which is sprayed incorporated in a non-toxic plasticizer so as to constitute 25% to 80% of the spray formulation and comprises a fatty acid ester, fatty acid or fatty alcohol, miscible with the plasticizer at above 50 DEG C., the sprayed filaments being compacted into a bundle which is wrapped and cut into lengths which are stored at above 20 DEG C. for at least 20 minutes to set rigid.  The waxy material is melted and dissolved in heated plasticizer, being insoluble therein below 35 DEG C. Alternatively, unheated plasticizer may be sprayed on in one booth and melted waxy material in a following booth.  Exemplary plasticizers are triacetin, glycerol di-acetate, glycerol di- and tri-propionates, di(methoxyethyl) phthalate, ethyl phthalyl methyl glycollate, triethyl citrate and mixtures thereof.  From 10% to 30% of filament weight of the wax or waxy material may be used. Exemplary fatty acid esters are glycerol monstearate, diethylene glycol stearate, ethylene glycol monostearate, polyethylene glycol monostearate, the triglyceride of 12-hydroxy stearic acid, the acetylated monoglyceride from hydrogenated lard, propylene glycol monostearate, and esters of polypropylene glycol; a mixture of glycol monostearate and hydrogenated acetylated monoglyceride may be used. Exemplary fatty acids are saturated acids of formula CnH2nO2, where n is from 10 to 24, e.g. lauric, myristic, palmitic and stearic acids, and unsaturated acids of formula CnH2n-2XO2, where n is from 10 to 24 and x from 1 to 5, e.g. erucic, elaidic, elaeostearic and angelic acids; such acids containing substituent groups (e.g. hydroxyl, carbonyl, chloro) may also be used. Exemplary fatty alcohols are stearyl alcohol (octadecanol) and cetyl alcohol (hexadecanol), with or without substituent groupings as above.  Waxes which may be used are carnauba, paraffin, spermaceti, montan and polyolefin waxes, beeswax, "Acrawax" (Registered Trade Mark) and castorwax (hydrogenated castor oil). They may be applied alone or with, before or after plasticizer. Quantitive process examples and completed filter test results are given.  The spray booth for the wax or waxy material is so heated and jacketed that any droplets not attaching to the filaments are maintained fluid and can be recycled.  Cooling devices may be mounted adjacent the booth filament exit, the adjacent filament-forwarding rolls having blades which scrape solid depositions therefrom for re-melting.ALSO:Tobacco smoke filtering element manufacture includes the steps of spreading out a plurality of filaments, melting a wax or waxy material having a melting point above 35 DEG  C. and spraying it on the filaments in a particle size of less than 30 microns (e.g. down to 0.5 micron) to form nodes and ridges thereon.  The filaments may comprise a tow of at least 10,000 continuous crimped cellulose acetate filaments of from less than 3 to 16 individual denier and 20,000 to 100,000 total denier and the waxy material be as highmolecular-weight compound which is sprayed incorporated in a non-toxic plasticizer so as to constitute 25% to 80% of the spray formulation, and comprises a fatty acid ester, fatty acid or fatty alcohol, miscible with the plasticizer at above 50 DEG C., the sprayed filaments being compacted into a bundle which is wrapped and cut into lengths which are stored at above 20 DEG  C. for at least 20 minutes to set rigid.  The waxy material is melted and dissolved in heated plasticizer, being insoluble therein below 35 DEG C.  Alternatively, unheated plasticizer may be sprayed on in one booth and melted waxy material in a following booth.  Exemplary plasticizers are triacetin, glycerol di-acetate, glycerol di- and tri-propionates, di-(methoxy-ethyl) phthalate, ethyl phthalyl methyl glycollate, triethyl citrate and mixtures thereof.  From 10% to 30% of filament weight of the wax or waxy material may be used. Exemplary fatty acid esters are glycerol monostearate, diethylene glycol stearate, ethylene glycol monostearate, polyethylene glycol monostearate, the triglyceride of 12-hydroxy stearic acid, the acetylated monoglyceride from hydrogenated lard, propylene glycol monostearate, and esters of polypropylene glycol; a mixture of glycol monostearate and hydrogenated acetylated monoglyceride may be used. Exemplary fatty acids are saturated acids of formula CnH2nO2, where n is from 10 to 24, e.g. lauric, myristic, palmitic and stearic acids, and unsaturated acids of formula CnH2n-2xO2, where n is from 10 to 24 and x from 1 to 5, e.g. erucic, elaidic, elaceostearic and angelic acids; such acids containing substituent groupings (e.g. hydroxyl, carbonyl, chloro) may also be used. Exemplary fatty alcohols are stearyl alcohol (octadeconal) and cetyl alcohol (hexadeconal), with or without substituent groupings as above.  Waxes which may be used are carnauba, paraffin, spermaceti, montan and polyolefin waxes, beeswax, "Acrawax" (Registered Trade Mark) and castorwax (hydrogenated castor oil). They may be applied alone or with, before or after plasticizer.  Quantitative process examples and completed filter test results are given.  The spray booth for the wax or waxy material is so heated and jacketed that any droplets not attaching to the filaments are maintained fluid and can be recycled.  Cooling devices may be mounted adjacent the booth filament exit, the adjacent filament-forwarding rolls having blades which scrape solid depositions therefrom for re-melting.