US2828752A

US2828752A - Fibrous tobacco smoke filters

Info

Publication number: US2828752A
Application number: US449872A
Authority: US
Inventors: Wallace T Jackson
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1954-08-16
Filing date: 1954-08-16
Publication date: 1958-04-01
Anticipated expiration: 1975-04-01

Description

April 1, 1958 w. T. JAcKsQN l 2,823,752

lFIBROUS TOBACCO SMOKE FILTERS l Filed Aug. 1e, 1954 4 sheets-sheet 1' Fig. 1

Fig. 2

,DR/orel ART F/LTE PA PEA?.

. V/lace 7.' Jackson INVENTOR.

Aprll 1, 1958 w. T; JACKSON FIBRoUs ToBAcco SMOKE FILTERS 4 Sheets-Sheet 2 Filed Aug. 16, 1954 @ER k MQ TQQ Wiz-:llame Z'Jac/cson INVENToR.

All

vBY :A

V .I ATTORNEYS April 1, 1958 w. T. JACKSON 2,828,752

FIBROUS TOBACCO SMOKE FILTERS Filed Aug. 16, 1954 4 Sheets-Sheet 3 .ATTORNEYS April 1 1958 w. T. JACK'SN 2,828,752

FIBROUS TOBACCO SMOKE FILTERS Filed Aug. 16, 1954 4 sheets-sheet 4 SECT/ON OF SP//VNERETTE SHOWING ONE CRIF/CE 16 /13 1l 24 25 F1 g. 9 /4 f zs f f :/`25 Y 23 f I O 5l/wel' Jackson J INVENToR.-

ATToRvNEw nitc FIBROUS TBACCO SMGKE FILTERS Application August 16, 1954, Serial No. 449,872

11 Claims. (Cl. 131-208) The present invention relates to tobacco smoke filtering material and elements thereof suitable for use in cigarettes, pipes, cigarette holders, and cigar holders. More particularly, the invention is concerned with a novel brous ltering material comprising an improvement in brous lters of the general type disclosed in pending U. S. patent applications of Crawford and Stevens, Serial Nos. 324,342, led December 5, 1952, now Patent 2,794,239 of June 4, 1957, and`374,l68, led August 14, 1953, now Patent 2,794,480 of June 4, 1957, to each of which reference is made.

In the aforementioned applications, newly discovered advantages of a certain type of brous tobacco smoke lter are discussed. According to Crawford and Stevens, a filter is prepared from a continuous strand of lamentary material and comprises a structurally unitary rodlike mass of bers and a wrapper encircling the mass, the bers as a whole being in substantial alignment longitudinally of the mass but substantially each of the individual bers having a plurality of short portions thereof crimped into diverging and converging relationship to the main ber axis, a plurality of the bers having physical bonds to contiguous bers at random points of contact. Very good results have been obtained in the use of such lilters for the removal of nicotine and tars from tobacco smoke, especially in view of the fact that the lters supply other requirements equally as necessary to the success of a tobacco smoke filter. A particularly advantageous embodiment of the Crawford and Stevens filter is that in which the lter is prepared from a synthetically spun, crimped, continuous lament tow, e. g. cellulose acetate. ln this form, the rodlike mass therefore comprises a segment of the tow in which the bers are coextensive with the mass. In its preferred form, the fibers of this filter have surface solvation bonds comprising coalesced portions of contacting bers.

Filtering elements of the general type described above are prepared by the cigaretting, i. e. by shapingl and wrapping with paper a tow which previously has been subjected to a special preliminary conditioning treatment. The special treatment or preliminary conditioning of the tow was found to provide an advantageous character to the material thus treated whereby properties requisite to (a) good cigarettingj (b) cigarette assembling (i. e. joining of the filter elements to Wrapped bodies of tobacco), and (c) filtering are vastly enhanced. Thus, the preliminary conditioning method results in a tobacco smoke ltering element with quite a distinct character as respects compactness, size, density, smoke channeling, cross-sectional ber distribution, air pressure drop, .resiliency, body, feel, rigidity, ber loss, porosity, integrity and the like. These properties are provided in such quantity and relationship that the material not only only is pleasing as a cigarette component but is susceptible of handling with processing apparatus normally used for cigarette manufacture and packaging. Also provided is the equally important requirement that in any given optates Patent Oi 'distribution of bers is less than in other areas.

. 2 eration the lamentary lter material produced exhibits its various characteristics uniformly and within close tolerance. The method is adapted for the continuous high speed conversion of crimped continuous lament tow to a smoke filtering material.

In its entirety, the method of Crawford andStevens The preliminary step of tow conditioning consists essentially of two principal operations: (l) lament separation, and (2) creation of an adhesive attitude among the separated laments. A third and more or less in- `cidental step involves the orderly collection of the lal ments of the treated tow under controlled conditions of tension and uniform presentation of the collected tow to a cigaretting means, e'. g. a garniture.

kPerhaps the most critical phase of the entire conditioning process is the step of lament separationwhich has been found to provide two requisite qualities to the tow. First, filament separation amounts to an opening of the tow in the respect that small compact bundles of laments within the tow are broken up to give a more uniform cross-sectional distribution of laments throughout theentire tow.. Uniformity manifests itself in the final product primarily through reduction in the normal tendency of the filtering material to causeY channeling of the smoke through areas in which the ber density, i. e.

Uniformity also manifests itself in an improved compactness, rigidity and resiliency ofthe product. Another characteristie imparted to the tow in lament separation is the'.

susceptibility, i. e., exposure of all or a large percentage of the individual filaments to treating materials in the' subsequent conditioning step, i. e. in the creation of Van adhesive attituderamong the laments. ln other Words, the step of lament separation results in the individual filaments being more vulnerable to a fluid treatment as well as in their having a condition wherein the laments assume a more uniform and dechannelized (debundlized) transverse distribution of bers. Exposure and suscepti` bility are manifested in the final product through an improved retention of uniformity, and through improved rigidity, resiliency and integrity. v

1t has been taught by Crawford and Stevens that filament separation is best accomplished through at least two distinct operations on the tow, each of which promotes' both uniformity of distribution and exposure, but the rst achieving primarily distribution and the second achieving primarily exposure. Thus, it has been indicated to be advantageous to conduct lamentseparation by means of the successive steps termed tow opening and tow banding, respectively. A Y

By banning is meant widening at the expense of thickness. converted to a web-like, i. e. ribbon-like conformation being, for instance, five to sixteen (usually about eight to fourteen) times its original Width and having little thickness so that all or at least a substantial majority of the individual laments are directly exposed and vulnerable to a spray from one or both sides of the banded web. ln other words, banding may be described as an operation for-greatly increasing the dimension of the tow in a first plane while maintaining a substantially uniform distribution of bers in Vthat plane and greatly reducing the dimension of the tow in a second plane perpendicular thereto. Banding is accomplished by means tending to move the filaments apart by movement more Patented Apr. ll, 1958 Thus, a banded tow is one which has been or less confined to a single plane and therefore banding assists in the dechannelizing and debundlizing of 'the tow. At the same time, a prior debundlizing of the tow appears toAbe necessary 'to the success of the banding operation.V

Debundlizing is largely accomplished by the operation of tow opening preceding the-banding step. Opening is nicely procured by the use -of tensional forces which take advantage of the inherent springiness of the tow to restrict it to an extent from which its reaction, upon release of tension, is to 4open or expand. Thus while openingalso facilitates banding, it primarily promotes uniformity of filament distribution in the-tow. Opening thus is importantA in providing a debundlized and dechannelized structure in thejinal product.; In accordanewith the terininoldgyhused herein, a dechannelized tow is one inrwhich there has beeneliminatedfor substantially reduced'anygtendency forY smaller groups of adjacent filaments to become associated as distinct compacted smaller bundles within thelarger mass or` bundle of filaments. Such a tendency of course inherently includes a tendency toward formation of channels, lt is necessary Vto remove and break up such grouping in order `that there be no smallvfiber-bundlcs present in the final product. Y

Therefore, a preferred method for the conversion of cellulose acetate tow into tobacco smoke filter elements comprises the successive Ysteps of (l) conducting filament separation by (a) opening, i. e. enlarging the diameter of a crimped tow supplied continuously, and (b) bandingthe thus'open'ed tow topform a ribbonlike web of relatively largelwidth andvsmall thickness, (2) creating' an 'adhesive attitude among the filaments of the banded tow by subjecting the latter to a spray of liquid plasticidzer, wbichhas a'solventaction on the 'filaments y(3 )V collecting the"treaied tow and presenting it to cigaretting means under uniform conditions adapted to retain within the tow characteristics imparted to it iny the first step, (4) cigrettingthe thus conditioned tow by condensing, shapinglwrapping, sealing and severingrit into desired lengths, and` (5)'stiffning the elements severed from the continuous length of material so produced by a curing treatment, i. e. aging, heating, `or both. The stifiened elements in suitable length then may be joined each to the tobacco body ofa cigarette as a filter tip, or they may be employed each'in a 'suitable length as a filter unit for a cigaretteor cigar holder or pipe. v Y

It vhas been appreciated for some time that possibly the most critical step in' the continuous conversion of running lengths of crimped'continuous lament tow into cigarette filters by the general'rnethod'as described above perhaps is the step of tow opening, which takes place as a part( of the filamentseparatiori phase. The easel of subsequent'processing. ofthe tow in standard apparatus as" well as the'charae'ter of thefinal product appears to be' very extensively influenced bythe manner of and success with which" the towV opening step is conducted. Tow' opening normally is accomplished continuously by means of a device which consistsof two pairs of cooperating tensioningrolls spaced along andiforming n path for movement of-the tow'siiccessively through the bites of the roll pairs: The downstream pa'ir is positively driven to grip and pull the tow against a restraining force applied by the Vupstream pair vof rolls which is composed of rolls retarded either by frictional'brakingy or by being positively driven at a slower speed than the positively driven tensioning rolls. The tension exerted onv the tow bythe downstream ,rolls in overcoming the retarding effect of the retarded rolls, which tension normally may be of the order of about 20 to 50 pounds, serves to straighten out Vthe crimp in the towwhereupon vat the emergence of"v the tow from-the nip of theV tension rollsv into azone' of relative relaxation, i; e.,frelatively little tension, the tow undergoes an expansion, i.V e., enlargement of'diameter and circumference and reduction of fiberdensity transversely, through the spring-.like action of the'f lamean-rc2.V Y. d ,s

ments in returning to their normal crimped condition,

and causing a puffing up ofthe tow body. That is to say,

a type of explosive expansion occurs within the tow to provide bundle breaking, i. e., disintegration of any individual compact bundles of filaments which may exist within the larger bundle forming the tow.

In other words, the tensioning apparatus subjects the tow to sufiicient tension to produce a restriction of substantially each strand which' straightens the strand by pullingout thecrim'ps andfresults, upon emergenceof..

the strand from thel nip ofrthepositively driven rolls into a zone of relative relaxation, in a more uniform distribution of filaments Within the strand as a result of inherent and elastic forces within the filaments of the strand. These forcesare exerted transversely by each filament in reassurning its crimped configuration and thus are exerted transversely of the strand and are more intense where filament density, i. e., the concentration of filaments is greatest. transverse displacement of filaments from zones of high filament density. Thus action herein termed tow opening or bundle breaking obviously is dependent upon the use of both'l (a) satisfactorily crimped and springy to'w andfb) zones of definite tension differential.

As suggestedabove, it is known that the more complete the blooming.action produced by the tensioning step, .the more easily the tow is processed in the equipment of the tobacco industry and the more perfect the character of the filter tipsfso manufactured. The present invention" provides forV improvement in the step of filament separation'and a consequent improvement in the physicalcharacter of the final product thereby produced as regards adaptability for the cigaretting and assemblingk Vof synthetically spun materials, so far as I am aware,

ha'veralways Vbeen in terms of the normal or usual liber sectionalshapes as employed in the textile art. ln other words, in the aforementioned Crawford' and Stevens applicatiohs, synthetic fibers, e. g. cellulose acetate, were describedv'as ybeingpreferably, for example, a yarn-type acetate" containing about 38.8% to 39.2% acetyl, etc.

Thisrmaterial Vnormally would be spun from round'holes" of a-sizedependingupon theY desired filament denier, and

wuldfafter solvent removal and solidification, have a somewhat irregular cross-'sectic'mV roughly in the shape of a clover leaf.

While suchv filaments react quite satisfactorily to the conditioningtreatinent, lnow have found that a new dry spun cellulosic filament of novel cross-sectional shape gives` an exaggerated' reaction to the tow conditioning' treatment of Vthe method of Crawford and Stevens and thereby produces fa product of very substantially Venhanced characteras regards'processing ease in all of the' subsequenty steps'(1`)lconditioning, (2) cigaretting, and (3) assembling, and as'regardsuniformity and quality of theV product iilteringelements prepared thereby.

, Accordingly, it is a primary'object of the present inventionto provide a new and improved fibrous tobacco smoke filter element.' A' second object of the invention is' to" preparetobacco' smoke filters from synthetically spun* continuous' filament'tow' 'composed 'of laments having 'a' Y-shaped eros`s=s'et:tion. A still further object" is to'pre'p'arefibrous' lter'sofimproved physical properties: Anotlierdbjectiis to'enliance the blooming,i. e; tow openingfirithelconditioniiig' ofa'rcrimped continuous filament towI foi-'fuse in'- preparation of? tobacco smoke filters; Another Vobjec'trisly thexy preparation of a" filterv elementi comi- Therefre, the lateral forces cause As a consequence, discussions posed of fibers having a Y-shaped cross-section. A still further object is to provide a lter having increased bulk,

resiliency and body. Another object is to provide a filter element where the superior bulk of the component Y-shaped filaments provides a more tightly packed rod without increasing its pressure drop. Another object iS the preparation of a fibrous lter having aligned fibers of a more uniform cross-sectional ber distribution. Other objects will be apparent in the following specication and claims.

The present invention resides in a tobacco smoke filtering element comprising an elongated structurally unitary rodlike mass of crimped synthetically dry-spun fibers and an annular wrapper encircling the mass, each ber of the mass being substantially coextensive therewith, the bers as a whole being in substantial alignment longitudinally of the mass but substantially each of the individual bers having non-oriented short portions thereof disposed randomly in diverging and converging relationship to the main ber axis, a plurality of the bers having surface solvation bonds to contiguous bers at random points of contact, a substantial portion of the bers having a substantially uniform Y-shaped cross-section,

the Y-section having legs of substantially equal length and of substantially equal shape, and the angles between adjacent legs of the Y preferably being substantially equal. Most advantageously the bers of the invention are prepared from single or mixed organic acid esters of cellulose derived from acids containing 2 to 4 carbon atoms, the filaments having a size of 1.5 to 43 denier. Most advantageously the laments are of cellulose acetate.

The invention is illustrated in the accompanying drawings in which Figure 1 is a reproduction of an actual photomicrograph showing the cross section of several Y-shapec laments of which the tobacco smoke lters of the present invention are made,

Figure 2 is a reproduction of an actual photomicrograph showing in cross section several clover-leaf laments made by the customary prior art method,

Figure 3 is an enlarged longitudinal section through a portion of a tipped cigarette assembled with a lter of the invention,

Figure 4 is a diagrammatic representation of the steps of the method for preparing a lter of the invention,

Figure 5 is a top plan view, partially cut away, of a preferred form of apparatus for conducting the method of the invention,

Figure 6 is a side elevation, partially cut away, of the apparatus of Figure 5,

Figure 7 is a view of the face of a spinnerette showing a plurality of filament forming orifices of equilateral triangular shape for dry-spinning Y-shaped laments suitable for the new tobacco smoke ltering element.

Figure 8 is a greatly enlarged representation of a spinning solution coming out of the triangular orices of a spinnerette such as represented in Fig. 7 and forming into Y-shaped cross-section filaments, and

Figure 9 is a schematic elevational view, partly in section, showing a spinnerette which has equilateral triangular filament forming orifices positioned in a suitable dry spinning cabinet which is equipped with suitable auX- iliary apparatus.

The filamentary material used for the lters of the present invention and methods for its preparation are disclosed and claimed in Raynolds, Abernathy and Smith U. S. patent application Serial No. 400,564, led December 28, 1953. The material may be prepared by forcing a suitable spinning solution through a spinnerette having a plurality of equilateral triangular shaped filament forming orifices therein and evaporating the solvent by drying the resulting filaments in a spinning cabinet under carefully controlled conditions of temperature while subjecting the laments to predetermined drafting. AVThe 4temperature of the solution and its rate of extrusion are so controlled as to secure optimum results.

Under the optimum conditions of solution temperature and composition, and of extrusion, drying and drafting,

the wet filaments as they leave the equilateral triangular adjacent legs of the Y will be substantially equal. The

Y-shaped cross-section is uniform along the length of the filament.

In general the spinnerette having the equilateral triangular orifices may be employed with any suitable spinning cabinet such as, for example, one of the forms illustrated in U. S. Patent 2,000,047 and 2,000,048.

The characteristics of the filaments and bers used in the present invention may be due to the intermeshing of the legs of the Y of the individual filaments in the lament bundle in such manner that each is reinforced by the other and the filament bundle has a resultant stiffness greater than that possessed by the normal cross-section fiber of equivalent denier because of the increased surface area. Such an arrangement would appear to result in increased blooming action and uniformity of ber distribution. It is noted that a circle taking in the three tips of the legs of the Y will be greater in diameter than one taking in the lobes of the well-known clover-leaf type of cross-section. This larger circle is, therefore, the effective area of the Y-shaped cross-section and may explain the increased utility of the Y-type of lament and ber for tobacco smoke lters. However, it cannot be definitely stated on what basis the improved lters and improved tow opening are achieved.

Referring to Figure 9 there is shown schematically a side elevation view, partly in section, of a spinning cabinet 11 and its associated apparatus by which the novel Y- shaped synthetic filaments and fibers may be manufactured. Mounted at the top of the cabinet is a candle filter unit 12 to which is connected a spinnerette 13 which has a plurality of orifices 14 therein which are of the shape of equilateral triangles. The face of this novel type of spinnerette with the equilateral triangular orifices 14 therein is shown in the greatly enlarged view of Figure 7. The candle lter may be uniformly heated by means of heating coils, not shown, which are positioned so as to surround candle filter 12, and through which coils may be circulated any appropriate heat exchange medium such as water maintained at the desired temperature.

Spinning solution of composition described hereinafter is supplied from conduit 16 through valve 17 to pump 18 which forces the solution at the desired rate to the candle lter unit 12, thence to spinnerette 13 through the equilateral triangular orices 14 from which it is extruded initially in the form of equilateral triangular filaments 25.

The laments 25 pass downwardly in the cabinet 11 While progressively losing solvent by evaporation until, in a substantially solidified condition they leave the cabinet 11 and pass around godet roll 20, which is positioned below the lower end of the spinning cabinet 11. Godet roll 20 is driven at a uniform speed by means, not shown, to give the desired draft to the'laments 25. From godet roll 20 the laments pass in the usual guide and are collected and assembled through other guides (not shown) with filaments from other spinning cabinets, moving at the same speed, to form a tow of a desirable number, e. g. 3000-30,000 continuous filaments. The tow is then sent through a crimping machine wherein a crimp of e. g. 2-16 crimps per inch is applied, and the tow is then fgrrned into a package, e. g. a ball warp, for transport todk assenso l tarded rolls 15 serves to pull the tow from the ball warp and subject it to a predetermined tension for the distance of the ratch, i. e. the distance between the nips of the roll pairs 14 and 15. The tensioning device is powered from a prime mover 16 through a speed reduction gear box 36, shaft 45, and a chain and sprocket arrangement to sprocket 39 which is free to turn on a shaft 46, the shaft 46 being normally free to remain stationary during rotation to the sprocket 39. Integral with the sprocket 39 is a clutch plate 47. A cooperating clutch plate 48 is keyed to the shaft 46 and its position on the shaft 45 controlled by a bell crank 37 adapted for manual operation. Movement of the bell crank handle in the direction indicated by the arrow in Fig. results in engagement of the

clutch plates

47 and 48 and thereby provides actuation of the shaft 46 keyed to clutch plate 48. Rotating with the shaft 46 is a sprocket 5G through which power 'is transmitted to the roll tensioning device by means of chain drives 51 and 52, a variable speed transmission 17, and a chain and sprocket drive between the latter and the pair of rolls 14.

The upper roll of the pair 14 is powered to rotate in a direction counter to the lower roll of the pair 14 in the direction as indicated by the arrows in Fig. 6. The action of these rolls 14 through the nip provided therebetween serves to pull tow from and through the braked rolls of the pair 15. The rolls of the

pairs

14 and 15 have elastic cushioning surfaces to provide suflicient traction on the tow. The rolls of the retarded pair 15 are spaced suiciently close to deform the cushion surface and introduce resistance through the friction of deforming. This provides a braking action by means of which a predetermined among of tension, for example, of the order of 20 to 250 pounds, is imparted to the tow in the ratch between the two pairs of rolls. During the application of tension the crimp in the tow is straightened out and upon emergence of the tow from the nip of the drive rolls 14 into a relatively relaxed state, the tow undergoes an expansion, i. e. enlargement of diameter and circumference and reduction of liber density transversely, through the puing action or spring-like action of the filaments in returning to their normal crimped condition.

As mentioned above, the action of the tensioning apparatus is dependent upon the existence of an adjacent zone to which the tow passes after tensioning and in which the tow is subject to relatively little tension. This is brought about by the use of a feed roll assembly indicated generally by the arrow at 1S and comprising a pair of drive rolls which are used to move the tow away from the tension zone, into and through banding apparatus, into and through a spray chamber and to collect from the spray chamber the treated filaments of the tow uniformly under controlled tension conditions. The feed roll assembly also serves to present the thus collected tow to the cigaretting means. The feed rolls are controlled synchronously with the cigaretting machine and the tensioning device in such a manner that they withdraw tow from the latter and feed to the former as required, under a tension of very small order, i. e. sufhciently merely to pass the tow through the banding and spraying means without allowing the accumulation of excessive slack. Thus, it may be said that movement of the tow between the tensioning device and the collecting device is a matter of little more than removal of the slack existing in the tow adjacent the tensioning means.

From the point of emergence from drive rolls 14 of the tow opening apparatus the tow is pulled under the relatively little tension afforded by means of the action of the feed roll assembly through the second unit of the filament separation means which is an adjacent banding apparatus in the form of air

jet banding devices

19 and 19a. The banding apparatus is spaced from the opening device a suitable distance, preferably at least about four times the banded width of the tow, to provide for gradual widening of the tow. The

banding devices

19 and 19a may each comprise a pair of parallel, spaced,` oppositely disposed at plates providing a slot-like aperture for pas- I sage of tow therethrough, at least one plate of the pair t being provided with openings for forming jets of air or other gas under pressure. In the apparatus illustrated, air is fed under pressure through lines as indicated into plenum chambers below the tow path. Apertured plates form upper walls of these chambers and permit air jets .to' be directedagainst the tow. The slot provided between the upper and lower plates is shallow and sutlciently wide to accommodate the tow in the widest condition desired. The outer .boundaries of the slot are formed by imperforate side walls. The banding jet devices may be of the type disclosed andclaimed in my U. S. patent application Serial No. 356,983, filed May 25, 1953 now Patent 2,737,688 of March 13,1956. The action of the jets of the banding jet deviceV is to strike the tow perpendicular-ly to its path of'movement and force the filaments apart, therebyforming a ribbon-like web having approximately -eight to sixteen times the original tow Width with a minimum of thickness. In this condition the filaments of the two are accessible to fluids which are applied by the next member Vof Vthe conditioning assembly. In using the two .

successive banding devices

19 and 19a, the rst is smaller 'than the secondrand allows for gradual and more efficient banding bylstagewise action. l v

From 'the banding apparatus 19 the tow emerges into a spray chamber 20 which is illustrated as having a slid- ,able glass windowY and an exhaust hood and flue. In the spraychamber, a uid bonding medium is applied by means` ofgoppositely disposed spray guns 21 and `22 to produce an adhesive attitude in the filaments. Most advantag'eously the spray is a liquid plasticizer having a solvent action Vwhichwill produce a tackiness in the filaments through surface solvation thereof at points of contact therewith of thejliquid'particles of the spray.

The plasticizer is fed to the

spray guns

21 and 22 from v a supply tank (notfshown) and lines leading through solel noid valves 38 and 6d. g These valves are opened to admit plasticizer to the gunsby energization of a circuit controlled by a suitable switch such as a spring-biased single throwv switchpor micro switch 61. The switch lremains open when the apparatus is inoperative. When the clutch plates'47 and 48 are brought into engagement by movee ment of the bell crank handle in thedirection indicated, the arm of the lever moving the clutch plate 48 contacts the switch and moves it into a position closing the circuit and thereby supplying plasticizer to the spray guns. This 0 cooperation of elements prevents the application of an excessive amountof plasticizer to the banded tow if operation of the machine must be temporarily halted. The

supply of pressure air to the spray guns may be controlled in a similar way but this is not necessary.

The plasticizer forms minute droplets at random points along the surface of substantially each of the lilaments of the tow in sufficient quantity so that substantially each of the iilamenjts will have a plurality of points of surface solvation along any length corresponding to the length of the smoke ilteringun'it which is to bre the ultimate product.` i Y Most advantageously, a plasticizing agent such as dimethoxyethyl phthalate or methyl phthalyl ethyl glycolate (carbethoxymethyl methyl phthalate) is employed. Other suitable nontoxic plasticizers which have nontoxic decomposition products and do not adversely affect the taste of tobacco smoke filtered through elements of the invention are dibutylV phthalate, tripropionin and acetyl triethyl citrate. The plasticizing agent preferably is sprayed on until the fibers contain 4 to 30% (preferably about 6- 15 by weight ofplasticizer. If desired, the temperature at which the fluid treatment takes place may be controlled.

In the course of its continuous movement the tow, wet

with plasticizer, Passes .out of tha Spray, Sabine? ZQEhIQUItr sambaA a `slot inthe side wall thereof and isreceived,.byartow..v

fluing means as desciribed in the;Crawfordand.Stevens-V applications -orpreferablyby a feed-.rollassembly such.l

cluding chain 72 transmittting power from a. variable.

speed transmission unit 73 which in turn receives its power from the prime mover 16 through the:A sprocket arrangement including chain 51. The upper roll 70 may be powered to turn with the lower roll 71 or may receive its drive merely by frictional engagement with the tow and/orf` lower roll 71. From the lower roll 71 the treated tow 26 passes up and into the horn 25 of the garniture.

Tow is discharged from the feed roll assembly and presented to a cigaretting means such as a garniture, i. e. cigarette-making machine into which it is drawn by the gripping and pulling action of the machine. The horn or die 25 of the garniture condenses and shapes the conditioned tow and discharges it onto a moving strip or ribbon of cigarette paper carried on an endless belt conveyor.

In the operation of a suitable type of garniture, as is well known in the art, the material being received, in this case the conditioned. tow 26, enters the condensing horn (e. g. 25) and is continuously discharged therefrom onto paper webv fed from a .roll at the same linear speed "as the material being received. The paper is lapped around the material, i. e. the rod of acetate filaments, in a shaping member and a standing edge of paper has adhesive continuously applied to it by a rotating disc. The standing paper edge is smoothed down over the adjoining edge by a stationary member and is heat-sealed into a permanent adhesive bond by a heated member. A rotating knife severs the paper-covered rod into appropriate lengths.

The garniture or cigaretting machine may be powered by the prime mover 16 through the

clutch plates

47 and 48 in a manner as explained above in connection with the tensioning device. A continuous conveyor belt 62 (Figs. 2.and 3) is driven through the action of pulley 63 which is keyed to the shaft 46. Other operating parts of ,the garniture may be synchronously driven by any convenient arrangement of shafts. (not shown) geared to the shaft'46. In: any event, the-driving arrangement preferably is such that movement of tow through the entire apparatusand application. of plasticizer are both controlled bymeans of the operation of the bell crank lever 37. Movement of tow and spray application thus are started and stopped in unison.

If desired, the paper covered rod formed by the cigaretting operation may be stilened by a heat curing treatment accomplished during passage of the rod Ythroughv a heated member prior to` severance. The same result may be obtained by subjecting the severed rods to heat `treatment suchas for instant storage in a chamber heated to 200 F. for a period of about two hours.

It is satisfactory to subject the finally wrapped rods of cellulose acetate .filaments -to a temperature of 160 F. for four hours where solvation has been accomplished with a plasticiz'er such as carbethoxymethyl methyl phthalate, although the treating time may be varied froml/z to 24 hours depending on..the.temperature and the particular plasticizing agent employed.. Any temperature within the range of 125 F. to BOGVF.' may be found satisfactory. It sometimes may be satisfactory to foregoa final heattreatrnentandy merely to allowthe paper-wrapped`rod to age atroom temperature for a period'of for instance, 24 hours.

18 comprises an. upper roll' 7 0 cigarettes, pipes, and cigarette and cigar holders. If the filter materialis to be used as a tip for cigarettes, known procedures forvmanufacturing filter tip cigarettes maybe used. That is to say, elements of appropriate lengthmay be fed to a joiner or other assembling machine which' serves to position the filter elements adjacent to tobacco bodies, join them and cut the joinedpieces at the proper points.

The product Yproduced vin accordance with the present invention is an article of manufacture or smoking device containing the same, the article comprising a rod, normally cylindrical in form and customarily substantially the size .of a cigarette in circumference and diameter, the rod being la compact, rigid, structurally unitary debundlized :mass of crimped cellulose acetatelaments of Y-shap'cd cross section, and a wrapper encircling the mass, each filament of themass being substantially coextensive there; with, the filaments as a whole being in substantial align# ment longitudinally of the mass but substantially each of the individual filaments having non-oriented short por- Y tions thereof disposed randomly in diverging and converging relationship to the main lament axis, substantially all of the filaments of the mass being positively bonded to contirrguous filaments within said structurally unitary rod at random points of contact of the filaments, the filaments of the mass being uniformly distributed throughout the transverse section of the mass thereby providing a dechannelized condition within the mass.`

Thus a rod in accordance with the terminology in this specification comprises a fiber mass, regardless of length or diameter, which results from conditioning and cigaretting a tow according to the invention and which is structurally unitary or substantially so, and capable independently of substantially retainingrits size and shape. The rods of the invention, though endowed with compactness and rigidity, are resilient and to a certain extent iiexible. The rigidity of the rod may be emphasized' bers of the same strand and coextensive, are in less than` exact longitudinal alignment due to the filament separationV operation, and particularly to the individual short .diverging and converging portions of the filaments comprising the crimps. Furthermore, the porosity and perviousness of the rod-like mass is preferably such that in passing longitudinally through the mass any given amount of tobacco smoke is split into numerous small streamsy and each stream guided through small channels formed by the surfaces of each group of adjacent filaments, channel size being such that good contact is thereby afforded between the filament surfaces and all portions of the smoke.

While the apparatus disclosed in the foregoing paragraphs has been found to bey most advantageous for reproduction of uniformity in products produced according to the described method it should be mentioned that some alternatives for individual elements are possible within the scope of invention. For instance in the step of filament separation, tow openingmay be accomplished by use in cooperation withV a pair of drive rolls of a trap box'having a weighted tongue to produce a braking action. The trap boxwould bea substitute for the pair of braked idler rolls 15. In other words, an opening device path in thetension zone between the two pairs of tensioni Such Va mechanism is disclosed and claimed in.`

rolls. copending Smith, U. S. patent applicationSeriall No;

416,010, filed March l5, 1954, now Patent No.` 2,790,208-f assays.;

of April 30, 1957. By employing about 3500 strokes per minute to deect the tow path about 2 to 3 inches per stroke, the method results in the periodic application to the already tensioned tow of a suddenly applied and suddenly released additional increment of tension su'icient to impart approximately an additional 8% stretch to the tow. This procedure improves and multiplies the opening effect to a substantial degree. It is less necessary, however, in preparation of the filter elements of the present invention than in preparation of elements from bers of ordinary cross section.

Banding might be accomplished successfully through the use of an expander bar as known in the art or as suitably modified. Thus one might employ a banding device comprising a surface presenting a portion of a cylinder and provided with two `diverging sets of tow contacting ribs at an angle to each other of, e. g., 60. With such a device it is contemplated that tow passing over the bar and in frictional engagement therewith will be banded in a manner similar to that occurring in the banding jet in that filaments would be transversely moved apart from each other, particularly in regions of high filament density to produce a-tow structure having a greatly increased uniformity of cross-sectional fiber distribution.

I claim:

1. A tobacco smoke ltering element comprising a structurally unitary, elongated, rod-like mass of cellulose acetate filaments and a wrapper encircling the mass, said mass comprising a segment of a crimped tow of continuous filaments, the filaments generally being in substantial alignment longitudinally of the mass but substantially every individual filament having non-oriented short portions thereof disposed randomly in diverging and converging relationship to the main filament axis, substantially every filament having surface solvation bonds provided by coalesced portions of contacting fibers, said portions containing a plasticizer having a softening action on the filaments, at least a substantial portion of the filaments having a substantially uniform Y-shaped cross section and the filaments of the mass being uniformly distributed throughout the transverse section of the mass thereby providing a dechannelized condition in the element.

2. A tobacco smoke filtering element as defined in claim 1 wherein the Y section of the Y section fibers has legs of substantially equal length and of substantially equal shape and the angles between the legs of the Y are substantially equal.

3. A tobacco smoke filtering element as defined in claim 2 wherein the individual filaments have a surface lubricant comprising a pharmaceutical grade mineral oil.

4. A tobacco smoke filtering element comprising a substantially structurally unitary, elongated, rod-like mass of synthetic thermoplastic fibers and a wrapper encircling the mass, the mass comprising a segment of a continuous filament tow having 4 to 18 crimps per inch, said tow being a bundle of filaments spun from a plurality of holes in one spinnerette assembled and substantially parallelized f with filaments spun substantially simultaneously from other spinnerettes and substantially every filament of the mass being substantially coextensive therewith, said tow having been treated to bring its filaments into substantially uniform cross-sectional distribution, the filaments of the mass being in general in substantial alignment longitudinally of the mass, a plurality of the laments of the mass being fused to contiguous filaments at plasticized random points of contact, and at least a substantial portion of the filaments having a substantially uniform Y- shaped cross-section.

5. A tobacco smoke filter comprising an elongated mass of 5,000 to 100,000 dry-spun, thermoplastic fibers of 1.5 to 16 denier per ber, said fibers being substantially oriented longitudinally of the mass, coextensive in length therewith, and coalesced to each other at random points,

said mass being a transversely-cut segment of ac'rmped l' tow of continuous filaments of a total denier of about 60,000 to about 250,000, and said filter being characterized particularly by the fact that the fibers have a substantially uniform Y-shaped cross-sectionQ 6. A tobacco smoke filter comprising an elongated, cylindrical mass of 5,000 to 100,000 dry-spun thermoplastic fibers of 1.5 to 16 denier per fiber, said fibers being substantially oriented longitudinally of the mass, substantially uniformly distributed across the cross-section of the mass, and coextensive in length with the mass, said mass being `a transversely-cut segment of a crimped tow of continuous filaments of a total denier of about 60,000 to about 250,000, the mass comprising at least a substantial proportion of fibers having a uniform, Y-shaped cross-section, the Y-section having legs of substantially equal length and of substantially equal shape, and the angles between adjacent legs of the Y preferably being substantially equal.

7. A tobacco smoke filter comprising an elongated, cylindrical mass lof 5,000 to 100,000 cellulose acetate fibers of 1.5 to 16 denier per fiber, said fibers being substantially oriented longitudinally of the mass, substantially uniformly distributed across the cross-section of the mass, coextensive in length with the mass, and coalesced to adjacent fibers at random points in plasticized portions of the fibers, said mass being a transversely-cut segment of `a crimped tow of 4 to 18 crimps per inch of continuous filaments, the segment having a total denier of about 60,000 to about 250,000, the fibers having a uniform Y-shaped cross-section.

8. A tobacco smoke filtering element comprising a substantially structurally unitary, elongated, rod-like mass of 5,000 to 100,000 cellulose acetate filament-s `and a Wrapper encircling the mass, the mass comprising a segment of a crimped tow of continuous filaments, said tow having 4 to 18 crimps per inch and being a bundle of filaments spun from a plurality of hole-s in one spinnerette assembled with filaments spun from other spinnerettes and the filaments of said mass being substantially coextensive in length therewith, said tow having been treated to bring its filaments into substantially uniform cross-sectional distribution, the filaments of the mass being in general in substantial alignment longitudinally of the mass, a plurality of the filaments of the mass being fused to adjacent filaments at plasticized random points of contact, and at least a `substantial portion of the filaments having a substantially uniform, Y-shaped cross-section.

9. A tobacco smoke filtering element comprising a substantially structurally unitary, elongated, rod-like mass of synthetic, thermoplastic, dry-spun filaments and a wrapper encircling the mass, the mass comprising a segment of a crimped tow of continuous filaments, said tow being a bundle of substantially parallelized filaments substantially simultaneously spun from a plurality of holes in one spinnerette assembled with filaments spun from other spinnerettes vand the filaments of said mass being substantially coextensive in length therewith, said tow having been treated to bring its filaments into substantially uniform cross-sectional distribution, the filaments of the mass being in general in substantial alignment longitudinally of the mas-s, a plurality of the filaments of the mass being fused to adjacent filaments at plasticized random points of contact, and at least a substantial portion of the filaments having a substantially uniform, Y-shaped cross-section.

10. An article of manufacture comprising an intermediate product foruse in the manufacture of fibrous cigarette filter tip elements of which the fibers are parallelized and coextensive, said intermediate product being a packaged, substantially untwisted, elongate, crimped, continuous filament tow of 5,000 to 100,000 filaments which in the aggregate are substantially parallel, the filaments being an unplasticized but plasticizable, dry-spun, cellulose acetate having an acetyl content of about 38-4l%, the filaments being of about 1.5 to about 16 denier per iilament; the tow having about 4A to 18"crmp`s' per inch'and the total denier of thetow being 'within the' range'of about 60,000 to about 250,000, the towhaving alow degree of lubrication providedby a ysmall amount, of the order of about 0.5% by Weight, of 'anon-,toxic lubricant comprising a pharmaceutical gradefmineral oil and at least a substantial portion of the lanent'shavin'g a substantially uniform, Y-shaped cross-section;A the crimp, the low order'of lubrication,v and the'shape andcharacter of the 'XfShaped'laments providing the tow with good blooming qualities and at least a substantial portion of the flamentshaving a ysubstantially uniform, Y-'shaped cross-section.

11. A packaged article of manufacture comprising-,an intermediate product :as-defined in claim 10`Wherein the Y section of the Y-shaped filaments of theV tow haslegs of substantially equal shape and theangles between adjacent legs of the lY preferably arelsubstantially equal;

References Cited in the tileI of this patent UNITED STATES` PATENTS 1,480,463 Petzel Ian. 8, 1924 1,773,969 Dreyfus Aug.,26, 1930 1,944,378v Thenoz Jani 23, 1934 2,259,150 ChildsV Oct. 14, 1941 2,476,582 Browne July 19, 1949 2,483,406 Francis Oct. 4, 1949v 2,508,799.v Reis May 23, 1950 2,637,893 Shaw May 12, 1953I 2,688,380` MacHenry Sept, 7, 1954 FOREIGN PATENTS 665,278` GatBritin Jan. 23, 1952 U S DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE oF CORRECTION Patent NoA 2,828,752

Wallace Te Jackson April l, 1958 It i's hereby Certified that error appears n the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as Corrected below.

Column l, line 69, strike out "only";` Column '7, line l9, for ufilaments 25H read filaments 25Y=1 Column 9, line 32, for "among" read amount-g line 59, for "suffioiently read msuffioientw; Column lO, line 22, for "two" read tow,

Signed and sealed this 24th day of June 1958,

(SEAL) Attest:

KARL AXLINE ROBERT C WATSON Attesting Officer Commissioner of Patents

Claims

1. A TOBACCO SMOKE FILTERING ELEMENT COMPRISING A STRUCTURALLY UNITARY, ELONGATED ROD-LIKE MASS OF CELLULOSE ACETATE FILAMENTS AND A WRAPPER ENCIRCLING THE MASS, SAID COMPRISING A SEGEMENT OF A CRIMPLED TOW OF CONUS FILAMENTS, THE FILAMENTS GENERALLY BEING IN SUBAL ALIGNMENT LONGITUDINALLY OF THE MASS BUT SUBALLY EVERY INDIVIDUAL FILAMENT HAVING NON-ORIENTED SHORT PORTIONS THEREOF DISPOSED RANDOMLY IN DIVERGING AND CONVERGING RELATIONSHIP TO THE MAIN FILAMENT AXIS, SUBSTANTIALLY EVERY FILAMENT HAVING SURFACE SOLVATION BONDS PROVIDED BY COALSCED PORTIONS OF CONTACTING FIBERS, SAID PORTIONS CONTAINING A PLASTICIZER HAVING A SOFTENING ACTION ON THE FILAMENTS, AT LEAST A SUBSTANTIAL PORTION OF THE FILAMENTS HAVING A SUBSTANTIALLY UNIFORM Y-SHAPED CROSS SECTION AND THE FIALMENTS OF THE MASS BEING UNIFORMLY DISTRIBUTED THROUGHOUT THE TRANSVERSE SECTION OF THE MASS THEREBY PROVIDING A DECHANMELIZED CONDITION IN THE ELEMENT.