EP0148818A1 - Filtre a tabac ameliore - Google Patents

Filtre a tabac ameliore

Info

Publication number
EP0148818A1
EP0148818A1 EP83902400A EP83902400A EP0148818A1 EP 0148818 A1 EP0148818 A1 EP 0148818A1 EP 83902400 A EP83902400 A EP 83902400A EP 83902400 A EP83902400 A EP 83902400A EP 0148818 A1 EP0148818 A1 EP 0148818A1
Authority
EP
European Patent Office
Prior art keywords
filter
tow
filter element
fibers
rod
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP83902400A
Other languages
German (de)
English (en)
Other versions
EP0148818A4 (fr
Inventor
Richard M. Berger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Filtrona Richmond Inc
Original Assignee
American Filtrona Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by American Filtrona Corp filed Critical American Filtrona Corp
Publication of EP0148818A1 publication Critical patent/EP0148818A1/fr
Publication of EP0148818A4 publication Critical patent/EP0148818A4/fr
Pending legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
    • A24D—CIGARS; CIGARETTES; TOBACCO SMOKE FILTERS; MOUTHPIECES FOR CIGARS OR CIGARETTES; MANUFACTURE OF TOBACCO SMOKE FILTERS OR MOUTHPIECES
    • A24D3/00—Tobacco smoke filters, e.g. filter-tips, filtering inserts; Filters specially adapted for simulated smoking devices; Mouthpieces for cigars or cigarettes
    • A24D3/04—Tobacco smoke filters characterised by their shape or structure

Definitions

  • This invention relates to a filter means, and relates more particularly to tobacco smoke filter elements. More specifically, the instant inventive concepts are primarily concerned with filter means for cigarettes, although the products of this invention are generally useful in other filter applications, particularly for tobacco smoking means, whether they be cigarettes, cigars, pipes of the like. Since filters for cigarettes are particularly commercially important, the basic embodiments of the instant invention will be discussed as they relate to the production of filtered cigarettes.
  • bondable continuous filamentary tows of substantially continuous thermoplastic fibers such as plasticized cellulose acetate fibers, polyethylene fibers, polypropylene fibers, nylon fibers and the like, have conventionally been employed as the starting material.
  • continuous filamentary tow is intended to define a material such as that which results when filaments extruded from a plurality of spinnerets are brought together and combined to form a continuous body of fibers randomly oriented primarily in a longitudinal direction.
  • the filaments are generally longitudinally aligned in substantially parallel orientation, but include crimped portions which may form short section running more or less at random in non-parallel diverging and converging directions.
  • Filtration efficiency which is the capacity to remove unwanted constituents from smoke, while highly desirable is only one factor important in producing a commercially acceptable filter.
  • Other factors such as pressure drop, taste, hardness and cost also determine commercial acceptance of these products.
  • cellulose acetate one of the most commonly used substances in manufacturing cigarette filters has a relatively low filtration efficiency. Increased filtration efficiency obtained by increasing the density or length of a cellulose acetate fiber may cause a pressure drop across the filter which is excessively and commercially unacceptable.
  • the use of activated carbon or other such materials having higher filtration efficiency may increase cost and deleterioi ⁇ sly affect taste.
  • a tipping over-wrap secured the segments to a tobacco column comprising a core of tobacco surrounded by a cigarette paper over-wrap.
  • cigarette filters produced in the foregoing manner required a porous or permeable plug-wrap in order that the air introduced generally through selectively provided perforations in the tipping over-wrap merged with and diluted the smoke coming from the tobacco column.
  • plug wrap has certain disadvantages in general discussed in some detail in U. S. Patents Nos. 3,313,306 and 3, 377,220, granted April 11, 1967 and April 9, 1968, respectively, the subject matter of which are incorporated herein in their entirety by reference, techniques for producing nonwrapped dimensionally stable filter elements were developed. The significance of producing a non-wrapped, dimensionally stable filter rod is even more pronounced for use in air diluted cigarettes in view of the high cost of porous plug-wrap materials.
  • the techniques for producing a non-wrapped dimensionally stable filter rod are highly useful and the best way presently known for such production.
  • the filtering material which may be continuous filamentary tow, staple fibers- or particulate in form is carried through the processing apparatus by an endless porous belt through which heated gas, such as steam, and coolant gas, such as air, are passed peripherally into the filtering material to bond the same into a dimensionally stable rod needing no plugr-wrap at all.
  • the belt was introduced, in part, as explained in the aforementioned patents, to eliminate the need to "pull" the filamentary tow, which is the most desirable commercial filtering material, through the system producing an undesirable tension on the individual filaments during processing, reducing the crimp initially present in the filaments and producing a rod with size, shapd and functional characteristics which are difficult t ⁇ control.
  • a highly desirable alternative to "pulling" the tow through the system or using a belt to "carry” the tow through the system would be to "push” the tow through the system.
  • a p neumatic technique for making fibrous bodies has been disclosed in commonly assigned U.S. Patent No. 3, 313, 665 granted April 11, 1965, the subject matter of which is also incorporated herein in its entirety. In this technique, air or other feeding gas under pressure is used to "push” the tow through a confined zone where it is heated and cooled to bond the product into a rod. Moreover, this technique enables a reorientation of the individual fibers transversely of the longitudinal dimension of the rod, a feature to be discussed in more detail hereinafter. The process disclosed in U.S. Patent No.
  • Cigarette filter elements normally have a diameter of about 8 mm in contrast to "wicking" cartridges which are generally well over twice that size in diameter.
  • the feeding gas may be substantially; dissipated through a foraminous area of relatively short: length due to the large circumference.
  • the present invention is, thus, directed to a novel fibrous body, particularly suitable for use in a cigarette filter element.
  • the bonded fibers are oriented within the fibrous body in an adjacent and overlapping relation to one another in generally successive layers extending generally transverse to the longitudinal axis of the fibrous body.
  • the periphery of the body is formed by bending some of the exposed edges or folds of the tow axially rearward, (i.e., about individual axes generally perpendicular to the longitudinal dimension of the filter rod) in overlapping fashion, to provide a smooth surface.
  • the fibrous body has a uniform cross-sectional diameter of approximately 8 mm and a relatively smooth circumferential surface for improved adhesive properties; it is transversely flexible while providing commercially acceptable hardness for handling and feel; it requires a relatively low quantity of material for a given pressure drop and yet has relatively high filtration efficiency for its low weight, making these bodies particularly suitable for use as cigarette filters.
  • a continuous filamentary tow by means of a jet which feeds the conveying gas, preferably air, at a specified angle into a confined chamber.
  • the air is preferably fed annullarly around the tow at the entrance end of the confined chamber to produce a venturi effect which draws the continuous filamentary tow into the chamber.
  • the use of a particularly small acute angle of air feed through the jet into the confined chamber, preferably between 0 and 20°, requires a much smaller volume of conveying gas to convey a given amount of filamentary tow than with previously available equipment.
  • the conveying gas may be conveniently dissipated through a limited porous section of the confined chamber without requiring a cross-section of the chamber so large that the fibrous body formed in the confined chamber cannot be commercially used for a cigarette filter.
  • the pneumatic feed in combination with a reduced take-off crosssection at the cooling zone bends the fibers of the tow perpendicular to the longitudinal axis of the confined chamber.
  • the arrangement of the fibers in the filter thus formed is substantially overlapping and generally transverse to the longitudinal axis of the filter rod being formed.
  • the fibers are cured with steam or other heated gas in this transverse overlapping relationship and the.
  • layers of the fiber are even further compacted in a preferred embodiment utilizing an extended steam soaking chamber and reduced crosssection cooling zone, prior to the rod being extruded from the apparatus.
  • the filamentary material is in a relaxed state and maintains its crimped shape.
  • secondary crimp is imparted to the fibers by extruding the filter rod at a linear rate of feed less than that of the incoming tow.
  • the material is forced against the wall of the confined cooling zone of reduced cross-section and thus a precision size and shape of the filter can be easily maintained.
  • the reduced cross-section of the cooling zone bends some of the edges of the filters axially rearward (i.e., about axes generally perpendicular to the filter rod length) to provide the smooth peripheral surface which permits reliable bonding of the wrap material thereto.
  • the product formed by this method is manufactured from continuous fibers in which the folded edges are bent rearwardly, there are substantially no loose ends or fibers exposed on the surface of the filter rod so formed.
  • the process and apparatus disclosed in the present invention makes much more efficient use of the filamentary tow may be divided into several portions, and each portion fed to a separate rod-forming station.
  • the filter rod produced by the instantly disclosed process may be bent without breakage, subsequent processing of the filter rod into, filter elements may be accomplished at numerous stations arrayed perpendicularly to the outlet end of the rod-forming station. It should, however, be borne in mind, that processing of the filter rods may be accomplished at stations generally in line with the rod-forming station.
  • Another effect of the transverse orientation of the fibers in the filter rod is that the air resistance to flow is opposite that of conventional non-wrapped cigarette filters.
  • Conventional filter elements have lower resistance to flow longitudinally and higher resistance to flow transversely.
  • the filters produced by the instant process have higher resistance to flow across their length.
  • the higher longitudinal resistance permits a weight saving of up to 40° of the weight of cdnventionally produced filters having the same resistance to pressure drop.
  • the lower resistance to flow across the width of the filter permits increased efficiency in air dilution such that fewer perforations in the tipping paper are required for filters produced by the instant process to achieve the same amount of dilution as conventionally produced air dilution filters.
  • a further advantage of the low resistance to flow across the width of the filter is that dilution of the smoke is much more uniform than with conventional filters, which, it is believed, leads to reduction of certain gas phase constituents of the smoke, such as carbon monoxide.
  • the particular feed jet used in the instant invention offers considerable savings in the amount of conveying gas required for manufacture of the filters. A savings of from 50-85% compared to jet used in prior pneumatic processes has been achieved.
  • a further advantage of the instant invention is its versatility. Using only one two item, it is possible to produce filters having a range of pressure drops simply by varying the input to the feeding jet and maintaining a constant take-off of the fibrous body produced by the jet, or viceversa.
  • Figure 1 is a perspective view, partially broken away for illustrative clarity, through a filtered cigarette incorporating a filter element according to the instant invention
  • Figures 2 and 3 are schematic longitudinal cross-sectional and end views, respectively, of a filter rod produced according to this invention
  • Figures 4 and 5 are similar views of a conventiona filter rod
  • Figure 6 is a schematic plan view of a preferred processing line for the manufacture of filter rods according to this invention.
  • Figure 7 is a transverse cross-section taken substantially on line 7-7 of Figure 6;
  • Figure 8 is a schematic elevational view thereof
  • Figure 9 is an enlarged schematic cross-section of a preferred embodiment of the rod-forming station.
  • FIG. 10 is a detailed perspective view of a filter element according to the present invention.
  • FIGs 11, 12, and 13 are detailed views in transverse section of the filter element of Figure 10 wherein each of those figures represents a filter element fabricated at a different respective ratio of the average iinear speeds of the incoming tow to the withdrawn filter rod in the apparatus of Figures 6-9.
  • a filtered cigarette according to the present invention is designated generally by the reference numeral 10 and comprises basically a tobacco rod 12 and a filter plug 14 secured together in a conventional manner by tipping over-wrap 16.
  • the tipping over-wrap has a multiplicity of circumferentially spaced performations 18 which serve to admit ambient air peripherally for mixture with the tobacco smoke in a well known manner.
  • the filter plug of the instant invention is schematically shown in Figures 2 and 3 and comprises a porous, dimensionally stable, axially elongated rod formed of a continuous filamentary tow of substantially continuous thermoplastic fibers bonded together throughout to be self-sustaining, the fibers being oriented within the filter plug l4.in an adjacent and overlapping relation to one another in generally successive layers extending generally transverse to the longitudinal axis of the filter element.
  • the overlapping layers shown schematically in Figures 2 and 3 results from the preferred processing techniques of the instant invention to be discussed in more detail hereinafter. These overlapping layers are in contradistinction to the continuous body of fibers oriented randomly in a primarily longitudinal direction as shown in the prior art illustrations of Figure 4 and 5 at 20.
  • these figures are schematic representations and that the individual filaments, in actual practice, include crimped portions which may form short sections running more or less at random in non-parallel, diverging and converging directions, the point of contact of the filaments being bonded together to form the porous or permeable element providing a labyrinth of smoke passages along the length of the filter.
  • Figures 2 and 3 wherein the fibers are oriented within the filter element in an adjacent and overlapping relation to one another in generally successive layers extending generally transverse to the longitudinal axis of the filter element, provides the resultant product with a number of unique properties.
  • the filter element may well have a resistance to flow which is higher in the longitudinal direction than in the transverse direction in contrast to conventional prior art filter elements, thereby enabling a relatively high ratio, of ventilation air to smoke in /the mixture. With such an arrangement, relatively high pressure drop in the filter element itself may be utilized because of the high dilution possible.
  • the resulting rod to be described in more detail hereinafter which is, effectively, a multiplicity of filter elements integrally connected in end-to-end relationship to each other, is relatively weak when subjected to tension at its ends, forces of this nature are seldom encountered in processing and use of such products.
  • the filter, rod or individual element has adequate "hardness", that is, transverse strength such as would be encountered in conventional cigarette manufacturing equipment or from the lips of the smoker in use.
  • the elongated rod may be bent during processing to facilitate the simultaneous production of a multiplicity of filter rods from a single tow in a manner to be described in more detail hereinafter.
  • the periphery 15 of the filter plug 14 is formed of bent back outer folded edges of even fibers, which bends overlap one another to provide a smooth surface. More specifically, during fabrication of the filter rod, as described in detail below, the rod is longitudinally introduced into a cooling zone of reduced cross-section which causes the rod periphery to bend axially backward. In other words, the individual folded edges of the fibers at the rod periphery are caused to bend about individual axes which are perpendicular to the rod length. These bent edges overlap to provide a smooth peripheral surface. This smooth surface does away with prior art fraying problems and permits reliable bonding bo tip-wrap material during production speed operation.
  • the overall processing line is designated generally by the reference numeral 30 in Figures 6 and 8 and, at the start, utilizes conventional techniques and devices for a number of the steps.
  • the tow 32 is passed from a conventional bale (not shown) through the usual tow preparation station 34 and into a conventional banding jet shown schematically at 36 and a plasticizer applying means shown schematically at 38.
  • a conventional plasticizer such as triacetin is sprayed on the banded tow in the plasticizer cabinet 38 in a well known manner.
  • the drawings illustrate the preferred embodiment of producing a multiplicity of filter rods from a single tow by slitting the tow 32 as ashown at 40 into a plurality of tow sections 32a, 32b, 32c, 32d, 32e, and 32f for further processing. It will be understood that although the tow has been shown as being slit into six sections, more or less tow sections could be utilized without departing from the instant inventive concepts.
  • the individual tow sections are delivered by rolls 42, 44 into rod-forming stations designated generally by the reference numerals 45a-45f, the details of one of which will be explained in discussing Figure 9 hereafter.
  • the resultant rods 46a-46f are fed by a pulling device designated generally by the reference numeral 48 and shown schematically as a pair of endless belts 48a, 48b into a common cutting means designated generally by the reference numeral 50 wherein the filter rods are arrayed in a cluster-like arrangement shown particularly in Figure 7 in which they are maintained in separately confined spaced relation to one another and subjected to a common cutting step.
  • the rods 32a-32f may be simultaneously transversely cut into a multiplicity of segments of substantially equal predetermined length, which may be equivalent to a single filter plug, a double filter plug or individual rods of any multiple filter plug length, such as are conventionally utilized in cigarette making machinery.
  • each group of segments is pneumatically conveyed through a separate tubular conduit 52a-52f to recovery or a packing station (not shown).
  • T! ⁇ e air tubes 52a-52f utilize conventional pneumatic techniques to feed the segments or elements through the conduits and need not be explained in further detail.
  • the rod-forming means 45 comprises basically an elongated hollow member 60 defining an elongated confined zone therewithin having throughout its length. substantially uniform cross-sectional size and shape at least up to the point where coolant gas is introduced as will be explained in more detail hereinafter.
  • the interior walls of the confined zone may be coated with polytetrafluoroethylene (Teflon) or other such material, if desired, to provide reduced friction therein.
  • Teflon polytetrafluoroethylene
  • the tow 32 is fed into the inlet end 62 of the hollow member 60 pneumatically by a unique tow feeding means designated generally by the reference 64.
  • the tow feeding means or jet 64 comprises an elongated tubular member 66 having a bore whose cross-sectional size and shape is slightly smaller than that of the confined zone within the hollow member 60, the outlet end 68 of which leads in the inlet end 62 of the hollow member 60.
  • a feeding gas which may conveniently be air under pressure is introduced into the tow feeding means 64 through the conduit 70 which communicates with an annular passageway 72 disposed concentrically around the tubular member 66 and terminates at its outlet end in a venturi throat leading into the inlet end 62 of the confined zone within the hollow member 60 in the same general direction as the tow 32 at an angle of about 0-20°, preferably about 10°, with respect to the longitudinal axis of the confined zone and at a feed ratio sufficiently high so as to pneumatically convey the tow through the confined zone and at a feed ratio sufficiently high so as to permit escape of at least a major portion of the gas from the confined zone a. along a porous portion 74 of the hollow member spaced downstream of the tow-feeding means 64.
  • the porous portion 74 of the hollow member 60 is capable of eliminating a major portion, and preferably substantially all, of the feeding gas because of the relatively low volume of feeding gas required utilizing the unique and preferred jet 64 of the instant invention. It is important to eliminate substantially all of the feeding gas at this point in the rod-forming means in order to enable the further processing steps to produce a uniformly bonded continuous rod. Utilizing prior art devices and techniques it has been impossible to efficiently dissipate the relatively large quantitles of feeding gas required in the production of a small diameter rod such as is required for use as a cigarette filter, nominally on the order of about 8 mm.
  • the jet 64 creates, at the inlet end 62 of the confined zone within the hollow member 60, a suction effect which serves to draw the incoming tow 32 into the confined zone at a rate proportional to the gas feed rate.
  • the rod-like formation of incoming tow being fed into the inlet end of the confined zone is of sufficient density so as to substantially prevent escape of the feeding gas backwardly through the incoming tow.
  • the tow After passing the porous portion 74 where at least the major portion of the feeding gas is dissipated, the tow is pushed into and through a heating station 76 which comprises a means for introducing a heated gas, preferably steam, into the tow, the heat rendering the tow bondable in a well known manner.
  • a heated gas preferably steam
  • steam under pressure is introduced through conduits such as shown at 78 into a multiplicity of peripheral passageways 80 to center the tow concurrently with respect to the direction of travel of the tow through the confined zone within the hollow member 60. At least the major portion of the steam will condense on contact with the tow delivering the heat necessary to render the tow bondable at the point of contact of the individual filaments in a well known manner.
  • Atow-soaking station 82 is provided in the form of an elongated portion of the hollow member 60 downstream of the steam ring or station 76, The tow-soaking station 82 provides extended residence time in contact with the steam so as to enable the steam to penetrate into the very core of the tow within the confined zone prior to setting of the rod.
  • a residence time of at least about 0.1 seconds and preferably 02.-0.5 seconds has been found desirable.
  • Patent 3,313,665 the tow was set substantially immediately after contact with the steam which, while adequate for relatively slow-rates of production, does not enable complete penetration of the steam to the center of the tow within the confined zone at speeds well in excess of 75 meters/min. and up to 500 or more meters/min. as is possible with the instant inventive concepts.
  • the tow is pushed into and through a means designated generally the reference numeral 84 for introducing a coolant gas, such as air, into the heated tow to bond the same into a self-sustaining, dimensionally stable, filter rod having the ultimate predetermined cross-sectional size and shape.
  • a coolant gas such as air
  • the cooling station 84 is separated into primary and secondary cooling means 86, 88, each of which has conduits 90, 92, respectively, communieating with a multiplicity of peripheral apertures 94, 96, respectively, arranged to feed the coolant gas co-currently with respect to the direction of travel of the tow.
  • one or more additional porous portions 98, 100 can be provided in the hollow member 60, preferably immediately before the first cooling station 86 and immediately after the heating station 76 as shown in Figure 9.
  • porous portions at this point in the processing line causes less of a problem than the porous station 74 prior to the introduction of the steam since the steam acts as a lubricant to the tow and, additionally, causes the tow to shrink slightly from the inside walls of the confined zone thereby avoiding snagging of the tow by the roughened interior of the porous portions.
  • the confined zone defined by the interior of the cooling stations 86, 88 is equal to the cross-sectional size and shape of the ultimate product and slightly smaller in cross-sectional size than the confined zone within the hollow member 60 prior to the cooling station.
  • This arrangement enables a final sizing of the product at the cooling station as the tow is set and produces a secondary packing of the filaments of the tow in the tow-soaking means 82 due to the slight resistance encountered at the cooling station and the relatively limp nature of the tow after it has been heated in the steam ring 76.
  • the reduced cross-section at the cooling station causes the perphery of the filter rod 14 to bend backward to form the smooth outer surface 15 described hereinabove.
  • the tow After passing through the cooling station 84, the tow has now been formed into a self-sustaining, dimensionally stable, filter rod having a predetermined cross-sectional size and shape which may be fed by the pulling means 48 for further processing. Due to the relative flexibility of the rods thus produced, they can be bent slightly as seen in Figures 6 and 8 to enable them to be passed into a single cutter head 50 for subsequent handling.
  • the filter rod is withdrawn from the rod-forming station at an average linear speed which is less than that of the incoming tow being fed into the inlet end 62 of the confined zone within the hollow member 60.
  • the fibers are reoriented within the confined zone into an adjacent and overlapping relation to one another in generally successive layers extending generally transverse to the directio of travel of the fibers. This reorientation initially occurs prior to contacting of the tow .with the heated gas and when the cooling station has a slightly reduced cross-section, the layers are further compacted in the tow-soaking station 82 prior to being contacted and set by the coolant gas.
  • the resultant product can readily be provided with a resistance to flow which is higher in the longitudinal direction than in the transverse direction, thereby enabling, as pointed out above, the relatively high ratio of ventilation air to smoke when the ultimate filter plugs are utilized in an air-diluted cigarette such as shown in Figure 1.
  • the product takes the form illustrated in Figure 11 wherein the 'fibers are oriented in an adjacent and overlapping relation to one extending generally transverse to the direction of fiber travel.
  • the ratio of the average linear speed of the incoming tow to the average linear speed of the filter rod being withdrawn is preferably within the range of from about 1.25:1 to about 4:1 to provide desirable filter products according to this invention.
  • the withdrawing rate of the filter rods may be readily controlled by selective operation of the pulling means 48 and the average linear speed of the incoming tow being fed into the confined zone may be readily controllably varied responsive to controlled variations in the feeding gas rate of the jet 64.
  • the exact dimensions and materials used may be substantially varied without departing from the instant inventive concepts, the following illustrative information is included for completing the disclosure.
  • a preferred rod-forming station 45 having a total length of approximately 30-5/8 inches from the point at which the feeding air is introduced at 70 to the point at which the secondary air is introduced at 92 has a steam-soaking section approximately 16 inches long from the point at which the steam is introduced at 78 to the point, at which the primary coolant air introduced at 90.
  • the length of the steam-soaking section can obviously be varied dependent upon the speed at which the processing line is operated, the important factorr being the provision of adequate residence time to enable the steam to penetrate to the very center of the tow within the confined zone therein.
  • the internal bore of the jet 64 is approximately .200 inches in diameter, with the diameter of the confined zone within the hollow member 60 being approximately 0.348 inches and the diameter within the cooling station 84 being approximately 8 mm.
  • the initial porous portion 74 of the rod-forming station is comprised of six rows of .039 inch diameter holes, sixteen per row,preceded by four rows of approximately 1/32 inch diameter, thirty per row. This relatively small porous portion is capable of dissipating a major portion, in fact substantially all of the feed air introduced at the jet 64. Using a 1.6/25000 No.
  • the tow weight in a 100 mm rod is 0.507 grams, with a 25 mm tip having a pressure drop of 4.0 inches of water and a retention of total particulate matter of approximately 66.2% .
  • filters may be produced with any desired pressure drop. For example, for 25 mm tips pressure drops ranging from 3.0 to 10.8 inches of water can readily be produced. Such filters have total particulate material retentions for a 25 mm tip of from 58.6 to 85.835, although variations may be recognized in individual runs.
  • the relatively low weight products of the instant invention have at least as good and generally better retention than prio-r art filters of a higher weight produced according to conventional techniques.
  • the products of this invention are self-sustaining, requiring no plug-wrap, enabling the production of air-diluted cigarettes in a significantly less expensive manner.
  • the instant ininventive concepts particularly considering the ability to produce multiple filter rods simultaneously from a slit tow, has obvious commercial advantages. Since the product has a smooth peripheral surface, in contrast to the embossed surface resulting from prior non-wrapped production techniques, adhesive bonding to the tipping overwrap is significantly enhanced while the bent nature of the fibers presented at the periphery of the rod avoids fraying problems. All in all, the instant invention enables the use of a minimum of raw materal to produce the highest number of filter units for a given labor cost. It is believed that the multiple processing technique of this invention can increase output from 2 to 6 times the current production levels.
  • the products are more symmetrical than is available with prior art techniques and by being forced outwardly against the walls of the confined zone within the cooling station are produced with machine shop precision.
  • the resistance to air flow is opposite to that with conventional filter, that is, the resistance is greater lengthwise than transversely enabling the use of less material for the production of a filter having a given pressure drop and providing improved and more uniform air dilution, requiring less perforation of the tipping paper for the same level of dilution and possibly enabling the reduction of certain gas phase constituents of the smoke.
  • the improved feeding jet of the instant invention offers a significant air saving on the order of perhaps 50% when compared to stuffer jets techniques and even more when compared to other prior art jet feeding devices.
  • machine efficiency is improved as discussed in some detail hereinabove.
  • the variability of the product produced is fully selective with any desired pressure drop within reason being obtainable using the same tow, but modifying the relative feed and take-off rates in the device.
  • thermoplastic material such as polyethylene, polypropylene and the like being applicable, but the preferred material being cellulose and acetate tow.
  • the individual and total denier of the tow may also be varied substantially, a total denier of between 5000 and 40,000 easily being accommodated to the techniques of this invention, with tows of up to 100,000 total denier even being useful as a starting material. As indicated above, it is less expensive to buy a higher total denier tow and slit it according to the instant invention to produce a multiplicity of bands than to initially buy a low total denier material. Since the product of this invention can be produced with a low total denier tow, the multiple processing techniques are particularly advantageous.

Landscapes

  • Cigarettes, Filters, And Manufacturing Of Filters (AREA)

Abstract

Corps fibreux axialement allongés, autoportants et de dimensions stables (14) ayant une section transversale de forme et de taille adéquates pour être utilisé comme filtres de cigarettes, produits à partir d'une mèche continue de filaments liables en fibres thermoplastiques sensiblement continues. Les fibres dans le corps de filtre sont orientées de manière à être adjacentes et à se chevaucher entre elles en couches généralement successives s'étendant généralement transversalement par rapport à l'axe longitudinal du filtre. Pendant sa fabrication le filtre traverse une station de refroidissement (80 et 88) de section transversale réduite de sorte que les bords périphériques radiaux des fibres sont repliés vers l'arrière et se chevauchent pour former une surface périphérique lisse sur laquelle un matériau de bout à enrouler peut adhérer facilement, sans qu'il soit nécessaire d'utiliser un papier de gainage à enrouler ou de doter le filtre d'un revêtement.
EP19830902400 1983-06-28 1983-06-28 Filtre a tabac ameliore. Pending EP0148818A4 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1983/001002 WO1985000092A1 (fr) 1983-06-28 1983-06-28 Filtre a tabac ameliore

Publications (2)

Publication Number Publication Date
EP0148818A1 true EP0148818A1 (fr) 1985-07-24
EP0148818A4 EP0148818A4 (fr) 1985-11-07

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19830902400 Pending EP0148818A4 (fr) 1983-06-28 1983-06-28 Filtre a tabac ameliore.

Country Status (4)

Country Link
EP (1) EP0148818A4 (fr)
JP (1) JPS60501637A (fr)
BR (1) BR8307732A (fr)
WO (1) WO1985000092A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0713905D0 (en) 2007-07-17 2007-08-29 British American Tobacco Co Cellulose acetate thread in filter
GB0920397D0 (en) * 2009-11-20 2010-01-06 Filtrona Int Ltd Tobacco smoke filter
CN115125674B (zh) * 2022-07-22 2023-08-29 广东鑫球新材料科技有限公司 一种内插接式空芯棉模具及成型方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1127494A (fr) * 1979-11-21 1982-07-13 American Filtrona Corporation Technique de fabrication de filtres

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55135581A (en) * 1979-04-12 1980-10-22 Mitsubishi Rayon Co Plug for tobacco filter
US4343320A (en) * 1981-02-25 1982-08-10 Rudolph Muto Cigarette filter with oblique partitions

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1127494A (fr) * 1979-11-21 1982-07-13 American Filtrona Corporation Technique de fabrication de filtres

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO8500092A1 *

Also Published As

Publication number Publication date
BR8307732A (pt) 1985-06-04
JPS60501637A (ja) 1985-10-03
WO1985000092A1 (fr) 1985-01-17
EP0148818A4 (fr) 1985-11-07

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