Document B5n4GvNqGG6ykZO6Re10RRke8

FILE NAME: Kent (KNT) DATE: 1956 Sept 4 DOC#: KNT026 DOCUMENT DESCRIPTION: Patent - Filter for Tobacco Smoke 2,761,798 -Patented'S ip tt 1 2,761,798 iFILTER FDR TOBACCO SMOKE .Harold W., Knudson, Norwood, Mass^ assignor to H & V -Specialties. C o .,'Im v East Walpole, Mass., a corpora tion {Massachusetts, aud P . Lorillard Company, New York, N . -Y., a corporation o f NewJersey, jointly ApplicationApril 24,1956, Serial-No. 680,241 2Claims. (CL 131--10) This invention concerns filter -means . for treating or conditioning tobacco smoke to the end of rendering it less irritating or toxic. Although there has been, much debate cn th e subject, it seems .generally agreed- that tobacco smoke, particularly . When inhaled; js at least-potentially. harmful, especially in the instance of .individuals suffering from cardio-vascular -and similar disorders. In the treatment of such cases, it has'been found that substantial reduction or complete cessation of smoking frequently produces even more harm'M effects because of shock, both physical and psychologi cal; to'the individual's system. A definite dilemma is thus presented, the. resolution of which in an individual case is never a true solution. Theproblem isone, which is; of in creasing -magnitude due to the increasing popularity -of -cigarette smoking. Even apparently physically sound individuals may .show minor blodd- pressure Changes.-due to- smoking,--but as to -these individuals; nose and 'throat irritation -is-of thegreatest concern. : My-invention-enables-the removal--of any desired-pro portion of the tars and nicotine present in tobacco-smoke --which-account`for its irritating properties- and potential toxicity. -'Actually, Of course, complete removal o f these substances is not desirable due to considerations of taste and flavor. -Moreover, -in--the-event- all of the tars and nicotine-are removed no "smoke" is-produced, i.-e,, the smoker draws into his mouth only colorless-and highly -unpalatable combustion gases. It -is nevertheless; signifi cant as illustrating the remarkable nature of my invention -that I can in fact achieve almost complete removal -of.the stated-.-subistances and even .within the: limits imposed: by practical factors such as the necessity .for maintaining a . free "draw"and the relatively short.length of-.filter-type :.cigar,and cigaretteholders. My. invention, as previously indicated,.takes> the. form : of-a: screening medium or filter ,disposed, in the .path of the tobacco smoke. .T h e:filter, -is distinguished .in .that it comprises a substantial proportion, of. asbestos, o r other small diameter fibers haying a: diameter, corresponding to . the .diameter, o f the smoke particles to be. removed and .being.of the order .of <1,1 to 0.6 micron; these,fibers being substantially .uniformly distributed ,in a loose, uncom,:pacted fashion in .carrier -.fibers o f substantially, greater . diameter, the. latter -being, present,in.. predominant pro portion. While mineral fibers, such, as- asbestos or. glass .fibers, of,.the..specified, diameters have, been found; to be . particularly :satisfactpry,fibers of a variety of other,ma.,terials, su,ch as .nylon,, cellulose, acetate,:viscose. rayon, ,.m^pplye8ter.jfibers..snch .as,Orion and Pacrpn,,are satis factory. provided their diameters are within the specified .range. 'A s a practical m atter it.is difficult and expensive to t>btain a~supply of small -diameter fibers all- of which have w-diameter within the-range-O.l-to' 0.6 micron-un-*i*ed With- any fibers of somewhatlarger. -diameter.- and the objects of the present invention can he- attaiaed-' by employing, as the source of small diameter fibers, a 2 fibrous-material, in which .some .of the'fibers have diameters outside Of the'O.l to 0.6 micron range, say rin th e -range pf-'Oil t o `2:0 microns, provided.a.substantial^proportion of -fibers o f the specified diameter are present 5 -'In;the ease of asbestos, it has been found that'fibers -of the-specified small diameter exist only in thefprm .of very-short lengths,-most-of them of.the order of 0,004 .to 0.012 inch in length, although a few may-be as much as 'O .U '-inch-'jn length. ;Asbestps which has been- incom10 -pleteiy -opened-may -contain "sticks" or bundles .which -appear1fibrous -and -which are considerably'longer than 54 inch;, but-these wifi haye diameters. greater titan; 2.0 mierens. While other fibers, particularly syntiiptic fibers, having*the specified .small 'ffiameter.;may, e x ^ in*longer 16 -lengths, substantially .all ofrthe small .diametpr '( f t i .to 0. 6 -micron)-fibers in the -fiiter of ;the present invention -have a length Ipss than154 .inch. -<ffhe -earner-`fibersm ay. b e conventional .textile'fibers, cotton, rayon, or other cellulpsic' fibers' bring preferred, 20 although wool and.nylon-fibers as well as fibers-of other synthetic- materials may also'be employed. '.These'fibers -normally-have-diameters o f `the order of cotton fibers, 1. e., 10 t o -25-microns, The length of the earner.fibers may-vary upwardly from' inch o r even.iess, although 25 . they are-preferably at least 54 inch long. and. may .be as much -as -several inches long, although normally, .of course, their-length will be no greater than theover-all dimensions-of the-filter. `I have; found that most smokers do not. consider the 30 .flavor of'the tobacco as objectionally impaired when from 3S%-6&% by* weight of the tars and nicotine .are .re moved-from-the tobacco smoke. . Accordingly,-my: in vention is- represented in- its preferred embodimenf by a filter-manufactured to -specifications which .provide`for 35 the removal-of from 35%^60%-by weight ofrthe smoke -particles; usually-40%-*-50%. Generally and preferably -such ' filter comprises -about :2% -20% small diameter fibers (0.1-0i6 micron) based on the total;-wright .of-all the fibers in the filter. 40 -It will, of-course, be-understood that the quantity of the tobacco -smoke particles removed is not entirely a function of- the concentration of the small diameter fibers since `the density. Of-`the'fiber mixture and the diameter and' length Of the' filter must also be considered. As to 45 -cigarettes, I customarily prepare- the filter (combining 2%~20% small diameter fibers) so that it has a-diam eter of about 0i81 to"0,83 -centimeter, a length o f abqut : 1;0 to 1:5- centimeters and an- apparent specific gravity (weight- per -unit-volume)--in- grains per cubic centimeter 5 0 o f f r o m 0 . 1 toG.23. 'The1density *of-the filter is obviously a-most important ' factor- 'since-there-canr-be nq- substantial interferehce-with "draw." It is this limitation- on density, or compactness particularly Which has prevented the development of a 55 really satisfactorytobacco smoke filter heretofore. 'In terestingly, conventional crepe paper filters and filters of the type compfising- spun viscose are capable a t best of removing not- m ore`than '5% -30% of the particles- mak ing up -tobacco- -smokebefore unreasonable `interference 60 with draw. t o the manufacture of -my filter, it is important that the blending o f the-.two classes of1fibers be as uniform-as .possible. 'Using-asbestos'fibers as the small -diameter fibers and cotton fibers as the carrier fibers, I customarily 65-effect the blending-on-conventional textile-machinery. "Thus,: I- feed together- to a picker-lapper two laps,-One comprising the cotton fibers, the other the asbestbs-ffiiers. :The.picker-lapperdelivers tbe laps to th e cylinder of a - cotton-carding* machine, 'the-product of-Which- is a sub70 stantially uniform web of the mixed fibers having a pre determined thickness. -Alternatively, -a-m ixing -picker such as is used in the wool industry may be employed in 3 4 the preliminary blending and die Wend may be delivered best explained with the aid o f diagrams. It has been de to the hopper of a wool carding machine. In any case, termined that the diameter of the particles constituting the working in the carding machine not only brings about tobacco smoke is about Q.l-0.6 micron. Since the di the desired blending but also operates to open up the ameter of paper fibers of the type heretofore employed in asbestos fibers as is manifestly necessary. A rod-shaped S tobacco filters is of the order of 10-25 microns, there is roving is formed from the web and cut into lengths as de presented a situation such as portrayed in Fig. 1, where termined by the length of the particular filter. Where A is a smoke particle, B is a cross-section of the paper encasement of the roving is necessary or considered de fiber, C is a slip line representing the flow of the air sirable, the roving may be drawn through a tubular mem stream, and D is a similar slip line with the Brownian ber, normally of paper, which is cut simultaneously with 10 movement of the particle (denoted by the wavy line F ) th roving. Better, the encasing material may be formed superimposed thereon. It is clear that if the smoke parr into a U-shape, as by the use of a suitable mandrel, the tid e is to be removed from the air stream, it must impinge roving deposited thereon and the whole passed through or collide with the fiber. In the situation represented, the a tubular die member wherein the edges of the material possibility of collisions are obviously remote. One solu are brought together, overlapped and secured, the roving 15 tion to the problem would be to accelerate the particle to being simultaneously compressed to provide die specified such an extent that it would be thrown from the air stream apparent specific gravity. In any case, additional me due to its greater inertia into a straight line path E to chanical strength may be imparted to the roving, when ward the surface of the fiber. However, such a high indicated, by braiding the same with cotton thread or the linear speed manifestly could never be realized under the like, or by applying a binder or bonding material to the 20 conditions involved in the problem to which the invention fibrous mixture to bind together the individual fibers or herein is addressed. a substantial proportion of them at their intersections to Another angle of attack would be to increase the num render the filter firm and resilient while retaining its loose ber of fibers in the path of the partide by doser packing uncompacted nature without impairment of draw. Ther of the fibers and to pass the partide through this tight moplastic or thermosensitive materials such as synthetic 25 maze so slowly that it would be bound to collide with resinous binders preferably having a softening or activa one of the fibers due to a diffusion effect. Obviously, tion point of 150-300 F. may be applied to the fiber this approach is also out of the question because of the mixture in the form of dry solid particles or liquid drop limiting conditions here involved. lets or solution or dispersion in a liquid medium. If The invention will be described with reference to cer desired, the binder material may itself take the form of a 30 tain embodiments shown in the appended drawings in fibrous material and may replace part or all of Cither which: the small diameter or the carrier fibers. When a thermo- Fig. 1 is a schematic representation of the path of a ;plastic or thermosensitive binder is employed, either in smoke; particle past a fiber of large diameter; the form o f fibers o r otherwise, a subsequent heating step Fig. la is a similar representation of a path of a smoke : is required, to activate it and bond the fibers together at 35 partide past a fiber of small diameter; their intersections to stabilize the fibrous mass in its loose Fig. 2 is an elevation, partly broken away and in sec uncompacted form having the required apparent density. tion, showing the filter of the present invention embodied When the binder material is applied to the fiber mixture, in a cigarette; care should be exercised to avoid coating the small di Fig. 3 is an end elevation of another embodiment of ameter fibers so as to increase their diameters above the 40 my invention; specified size. The proportion of binder material to the Fig. 4 is a view in elevation, partly broken away and in total fiber'mixture is usually about 10%-25% by weight, section, of a smoking pipe embodying the present inven preferably about 15% by weight. tion; and I t is to be clearly understood that the previously stated Fig. 5 is a view in elevation, partly broken away and range on small diameter fiber concentration is not critical, 45 in section, of a cigarette holder embodying the present for I may include either a substantially higher or a sub invention. stantially lower proportion of such fibers. Even with Fig. la is representative of the mechanism of the filtra amounts aslow as 1%, I can effect a distinct improvement tion as effected according to the invention. Here, A' over crepe paper or ail-cotton filters for example. How is the smoke particle, B' is a cross-section of a small diam ever, for best results the content of small diameter fibers 50 eter fiber, preferably an asbestos fiber, having a diameter (0.1-0.6 micron) should not be much less than about 2% approaching that of the smoke particle, and C' and D' are by weight of the total fiber mixture, preferably at least slip lines as in Fig. 1, wavy line F ' denoting the Brownian 5%, Depending upon the demand, the concentration of movement of the partide as in that figure. In this in small diameter fibers in some cases may be as high as stance, the displacement of the slip lines around the fiber or higher than 30%, despite the fact that at this point 55 is very slight indeed, and, as a consequence, the particle is there is definite impairment of tobacco taste and flavor. almost certain to collide with the fiber and be removed In the case of filter masses including from 5% to 30% by from the air stream--especially when one considers the weight of small diameter fibers there will be present from 70% to 95% by weight of carrier fibers having a diameter deviation resulting from the Brownian movement Moreover, it should be pointed out that the partide on the order o f cotton fibers. Such a filter mass prefer 00 in Fig. la would not need to be accelerated to nearly ably has substantially no greater, resistance to draw than as high a linear speed as the partide in Fig. 1 before the an equal volume erf the cigarette tobacco. The importance of using small diameter fibers of the inertia of the particle would cause it to deviate sufficiently diameter indicated cannot be overly emphasized. Fibers from the path represented by the slip lines to bring about pf greater diameter are relatively ineffective, while smaller 05 its collision with the fiber. diameter fibers have the disadvantage of contributing dis The carrier fibers combined in my filter serve to main proportionately to th air resistance and so are practically tain the structure sufficiently open to allow for easy inoperable. passage of .air. In the absence thereof, the density of Tobacco smoke, as well understood, represents a disper the filter would be such that it would be virtually im sion o f solid and liquid particles in air, the dispersion 70 possible to draw any smoke through it. As most pref being extremely stable by reason of the small size of the erably, manufactured, the resistance of the filter is sub particles, which makes the effect o f gravity negligible stantially no. greater than the volume of tobacco as con compared with the effect of convection currents and tained in a cigar, cigarette or pipe. Even under these Brownian movement conditions, upwards o f 35% -50% of the tars and nicotine The manner in which my invention works is perhaps 75 are effectively removed. s 6 8,?6 1 ,768 Forms which my invention may take are illustrated in more efficient than a conventional filter freshly inserted Figs. 2 to 5, in which the filter material is indicated by the in the holder. numerals 10, 10', 10" and 1C'" respectively, and may be This application is a conti .'nation in part of my parent assumed as combining cotton fibers or other fibers as the application Serial No. 260,187 filed December 6, 1951, carrier fibers and Bolivian blue asbestos as the small di 5 now abandoned, and of my copending application Serial ameter fiber component, such asbestos being particularly No. 384,673 filed October 7, 1953. preferred for use according to the invention. In Fig. 2 the Although I have herein described specific embodiments material is shown encased within a cigarette tip 12 which of my invention, I do not intend to limit myself solely may simulate ivory or cork, for example, the tip having thereto, but to include all of the obvious variations and a slightly greater diameter (exaggerated in the drawing) 13 modifications within the spirit and scope of the appended than the body 14 of the cigarette and being secured claims. thereto by means of a suitable adhesive. In this em I claim: bodiment the fibrous mass 10 is in the form of a roving 1. A tobacco smoke filter comprising a loose mass of having the carrier fibers generally oriented in the direc intermingled fibrous material having an apparent density tion of travel of the tobacco smoke. Fig. 3 affords an 15 from 0.1 to 0.23 gram per cubic centimeter, said mass enlarged tip-end view of a cigarette construction in which including a predominant proportion of carrier fibers and the filter material in the form of a loose fibrous web 10' a lesser proportion of small diameter fibers, said carrier is distributed in the folds of a conventional crepe paper fibers having a diameter on the order of cotton fibers and filter 16, relatively loosely formed. As shown in Fig. 3, said small diameter fibers having a diameter corresponding the crimps of the crepe paper extend generally in the to the diameter of the smoke particles to he removed direction of travel of the tobacco smoke. This increases and being of the order of 0.1 to 0,6 micron. the efficiency of such a paper filter not less than 500%, 2. A cigarette having a filter member for removing a assuming a weight ratio as between the fibrous filter ma substantial amount of the tars and nicotine from the terial (comprising 2% -20% small diameter fibers) and smoke from said cigarette, said filter member comprising the crepe paper of approximately 1:2. 25 a loose mass of intermingled fibrous material having an The filter construction in the pipe represented by Fig. 4 apparent density from 0.1 to 0.23 gram per cubic centi is shown as including a paper casing 18. A cloth casing, meter and having substantially no greater resistance to for example either finely woven or open mesh, may be draw than an equal volume of the cigarette tobacco, and substituted. said mass including from 70% to 95% by weight of car- The filter disposed in the cigarette holder of Fig. 5 0 rier fibers having a diameter on the order of cotton fibers is also shown as including a casing 20 of paper or equiv and from 5% to 30% by weight of small diameter fibers alent material. Because of the greater efficiency of the having a diameter corresponding to the diameter of the filter, it becomes loaded with tars and nicotone much smoke particles to be removed and being of the order of sooner than conventional filters and accordingly should 35 0 1 to 0.6 micron. be changed more often. But the filter, even after the smoking of say ten cigarettes is still upwards of 200% N o references cited. Sept. 4, 1956 H. W. KNUDSON FILTER FOR TOBACCO SMOKE Filed April 24, 1956 2,761,798 Jtilcgy.jtcx,. ^ VvvvvvwwwvwJLvyyvvw.pC so As*