US3656484A - Filter - Google Patents

Filter Download PDF

Info

Publication number
US3656484A
US3656484A US775390A US3656484DA US3656484A US 3656484 A US3656484 A US 3656484A US 775390 A US775390 A US 775390A US 3656484D A US3656484D A US 3656484DA US 3656484 A US3656484 A US 3656484A
Authority
US
United States
Prior art keywords
fibers
filters
filter
flock
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.)
Expired - Lifetime
Application number
US775390A
Other languages
English (en)
Inventor
John D Roberts
John D Ellenberg
Charles H Ketih
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.)
Celanese Corp
Original Assignee
Celanese 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 Celanese Corp filed Critical Celanese Corp
Application granted granted Critical
Publication of US3656484A publication Critical patent/US3656484A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • A24D3/02—Manufacture of tobacco smoke filters
    • A24D3/0229—Filter rod forming processes
    • A24D3/0233—Filter rod forming processes by means of a garniture

Definitions

  • ABSTRACT Aerosol filters are formed from [56] References C'ted short synthetic fibers containing a bonding agent by confining UNITED STATES PATENTS a random array of said fibers having an orientation predominantly transverse to the longitudinal axis of said filter in an 3,552,400 1 971 Berger et a1 "131/267 X area having the desired configuration and activating the bond-hackney et al. 1 3 agent to form a coherent article 3,050,430 8/1962 Gallagher ..13 l/268 UX 3,068,873 12/1962 Allman, Jr. et a]. ..131/l0.7 3 Claims, 2 Drawing Figures HEATED COOLING VACUUM FLUID HEATED FLUID PATENTEDMH 18 I972 13, 656,484
  • the present invention relates generally to the formation of aerosol filters, and more particularly to cigarette filters.
  • the cigarette filters of the present invention comprise a substantially cylindrical rod comprised of short synthetic fibers bonded at their points of contact with one another by a suitable bonding agent.
  • the arrangement of the fibers within said rod may be described as random with the exception that the fibers are predominantly lengthwise oriented in a primarily vertical plane.
  • the filters of the present invention are preferably formed by dispersing a plurality of short fibers associated with a latent bonding agent into a rapidly flowing, preferably turbulent, air stream, sweeping said fibers in said air stream into a cylindrical zone to form a rod conforming to the interior dimensions of said zone, confining said fibers in the cylindrical configuration by wrapping a porous belt about the rod as it exits from said zone in order to transport said rod through succeeding processing zones, removing air from the confined fibers, heating the rod to activate the bonding agent therein and form a coherent structure, cooling the coherent structure, removing the belt from about the coherent structure, treating the surface of the coherent structure to remove irregularities therefrom, and cutting the coherent structure to the desired length.
  • FIG. 1 is a side view of the apparatus described in the specification.
  • FIG. 2 is a cross-sectional view of a cigarette filter showing the transversely oriented fibers.
  • Aerosol filters particularly cigarette filters
  • Paper filters are generally characterized by a higher filtration as measured by smoke removal efiiciency at a given pressure drop, but suffer the disadvantage of adversely affecting taste and odor of the delivered smoke stream. Moreover, the phenol selectivity of paper filters is generally significantly lower than that available with conventional tow filters. Also, paper filters are susceptible to collapse during smoking, whereby the filter medium may become separated from the containing wrapper, permitting the smoke to channel about the medium and arrive at the smokers mouth essentially unfiltered.
  • tow filters particularly bonded cellulose acetate tow filters, are more successful in selectively removing phenols, and generally exhibit acceptable compressibility, i.e., resistance to lateral deformation, but would desirably exhibit enhanced smoke removal efiiciencies without loss in organoleptic quality of the delivered smoke stream.
  • the principal object of this invention is to provide an aerosol filter especially adapted for the filtration of tobacco smoke, characterized by high filtration efficiency, suitable compressibility, and an aesthetically acceptible delivered smoke stream.
  • a gas filter consisting essentially of discrete fiber elements bonded at random points of contact therebetween into a structure wherein the predominant orientation of the fibers is transverse to the gas stream path.
  • the present filters may be characterized as being of lower weight and improved compressibility at equivalent pressure drop and smoke removal efficiency in comparison with conventional continuous filament tow filters.
  • U.S. Pat. No, 2,855,937 describes a structure used by disposing fibers vertically on a paper wrapper and then forming a cylindrical rod therefrom wherein the fibers intermesh" with each other and are directed toward a common center. While this construction provides transverse orientation of the fiber elements, it will be seen by inspection that the concept requires a cross section having a variable density. Accordingly, the concentrated mass of interrneshed fibers at the common center tends to force the smoke to the periphery of the plug where a relatively low density of the medium is available to act on the smoke stream. Acceptable compressibility, as well as the construction methods, necessitate a stiff wrapper, and production techniques are extremely critical.
  • U.S. Pat. No. 3,225,390 emphasizes the desirability of increasing the transverse orientation of loose fibrous material in filter plugs to enhance the lateral strength thereof, and discloses formation of plugs from a web having about 25 percent to 50 percent of the fibers therein oriented in a direction 30 of the perpendicular to the axis of the plug being formed.
  • the desired effect on filtration efficiency resulting from this limited reorientation of fiber elements is necessarily minimal, which is also the failing of some other suggested approaches, such as those of U.S. Pat. Nos. 2,805,671 and 3,033,212.
  • a further and more specific object of the present invention is a provision of a cigarette filter rod having a uniform cross-sectional density, a high order of resistance to lateral compression even without any wrapping material, and sufficient longitudinal coherency or structural integrity to permit handling in subsequent processing of relatively long lengths thereof without splitting or cracking.
  • Another major object of the invention is the provision of an uncomplicated and economical process for manufacturing the aforesaid filters in a continuous, high-speed, commercial scale.
  • a still further object is to provide a manufacturing line utilizing equipment especially adapted to afiect the process for making such filters.
  • the filters of the present invention are prepared from short fibers of approximately 0.5 mm. to 8 mm., and preferably 1 mm. to about 3 mm. in length. For the sake of convenience, these fibers will be referred to herein as flock.
  • the flock utilized in the preferred embodiment of the present invention is prepared from filamentary materials which preferably comprise organic derivatives of cellulose such as esters or ethers thereof, e.g., cellulose organic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose benzoate, cellulose acetate formate, cellulose acetate propionate, cellulose acetate butyrate, and the like, and ethers such as ethyl cellulose etc.
  • the esters may be ripened and acetone-soluble, such as conventional cellulose acetate, or may be substantially fully esterified, i.e., contain fewer than 0.29 free hydroxyl groups per anhydroglucose unit, such as cellulose triacetate.
  • continuous filaments are spun from a suitable spinnerette of conventional design, taken up into a raw tow of a type well known in the cigarette filtration art, and packaged, preferably in a bale.
  • the continuous filament tow may then, optionally, but not necessarily, be removed from the bale and passed through a conventional banding jet and a subsequent opening means which serves to deregister the crimps in the filaments.
  • a suitable device for performing this operation is shown, for example, in U.S. Pat. No. 3,156,0l6.
  • the tow may be passed through a means for applying a suitable plasticizer and/or adhesive bonding agent thereto.
  • a suitable applicator for this purpose is shown, for example, in Us. Pat. No. 3,387,992.
  • Other applicators such as wick applicators or jet spray means may be utilized for this purpose.
  • the plasticized tow is then passed through a cutting device which severs the tow into the desired lengths.
  • the tow may be cut into short lengths prior to application of the plasticizer, and the plasticizer may then be sprayed onto or otherwise applied to the chopped fibers.
  • the plasticizer may be mixed with the fibers as they are in the turbulent stream jet prior to rod formation.
  • Plasticized short fibers thus prepared are then passed into a holding bin or other suitable container, or may be passed directly into the apparatus of the present invention.
  • flock prepared in the manner described above is passed to a feed loop 12.
  • the feed loop 12 conducts a rapidly moving stream of flock past the opening oftube 14.
  • the flock is then blown into tube 14 which terminates within housing 16.
  • Flock blown into nonporous tube 14 is compacted into rod form with the individual fibers being predominantly aligned in a transverse direction. This transverse alignment is attributable to formation within the nonporous tube and the presence of preceding fibers which serve as an impact barrier.
  • Belt 18 is threaded around pulleys 20 and 22, at least one of which provides a rotary motion to belt -18.
  • a vacuum chamber 24 which is employed to create an area of vacuum used to draw the flock into tube 14. Chamber 24 is to be considered optional since the air stream alone may be sufficient to convey the flock into tube 14.
  • the flock and belt pass through heating chambers 28 and 30 wherein the flock is subjected to a heated fluid which activates the bonding agent within the flock to produce bonding between the individual fibers and create a coherent cylindrical structure.
  • the heating chamber is shown as a two-part device.
  • the heated fluid is passed downwardly through the flock and in portion 30 the heated fluid is passed upwardly through the flock.
  • both sides of the flock are uniformly heated to obtain uniform bonding.
  • the preferred fluid in the present invention is heated air.
  • other gases or steam may be employed with equally desirable results.
  • the flock is passed into a cooling chamber to complete bonding.
  • This chamber like the heating chamber, is a two-part device designated in the drawings as 32 and 34.
  • cool air is passed in one direction through the flock in the first segment of the cooling chamber and in the opposite direction in the second segment of the cooling chamber.
  • the flock and porous belt exit from the cooling chambers 32 and 34 and the porous belt is then opened from about the coherent cylinder of flock and rotates around pulley 22 to return to the initial phase of the operation.
  • the coherent bonded rod 36 extruded from the operation then passes through a skinner device 38.
  • the skinner device 38 is preferably a Teflon coated gland having a heating source around the opening therein.
  • Passing of the rod through skinner 38 serves to remove the longitudinal seam created by belt 18 from the surface of the rod, as well as any other surface irregularities. After removal of surface irregularities by passing of the rod 36 through skinner 38, rod 36 is then passed to a cutter 40 which is timed to sever rod 36 into the desired lengths.
  • flock may be prepared from other fiber-forming polymers.
  • suitable polymers are the polyamides such as nylon, polyesters such as polyethylene terephthalate, polyglycolic acid and copolymers thereof, acrylonitrile polymers and copolymers, polymers and copolymers of olefin and vinyl esters such as ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, and the like.
  • the preferred plasticizer used in conjunction with the the preferred cellulose ester fibers of the present invention is triacetin.
  • suitable plasticizers such as dibutyl phthalate, ethyl glycolate, triethyl citrate, polyalkylene glycols and esters thereof, or the like may be employed. It will also be understood by the skilled artisan that a suitable plasticizer or adhesive bonding agent may be employed when using other of the above described fiber sources.
  • filtration materials to the flock prior to filter formation, e.g., by addition of such materials to the rapidly moving air stream along with the flock.
  • Particularly suitable materials include activated carbon, alumina, silica gel, diatomaceous earth, and other high surface area solids.
  • additives such as wood pulp and non-bonded fibers may be employed. Generally, these additives will be used in amount of from about 2 to about 50 percent of the total weight of the filter and more preferably from about 5 to about 20 percent of the total weight. It is to be understood, of course, that the amount employed will depend to a degree upon the particular additive being used.
  • the fibers described herein will have a dpf i.e., denier per filament of from about 0.5 to about 25, and even more preferably from about 1.0 to about 5. With a dpf much above 5, there is a sacrifice in filtration performance. Because of the structure of the present filter, it is possible to utilize lower dpf fibers without a sacrifice in the compressibility, i.e., resistance to lateral deformation, than has heretofore been experienced in utilizing these lower dpf fibers.
  • While the present filters have sufficient structural rigidity to function without a supporting wrapping, it is within the scope of the present invention to use additional wrappings about the filters, if desired.
  • filters prepared inaccordance with the procedure described herein need weigh only about 60-80 percent (exclusive of wrapping) as much as conventional acetate tow filters having satisfactory pressure drop (resistance to draw) and S.R.E. (smoke removal efficiency). At the same time, this light weight does not detract from desirable filtration.
  • present filters of 20 mm in length and 8 mm. in diameter, having a pressure drop of about 20-90 mm. of water weigh about 0.08 to about 0.14 gram and have a smoke removal efficiency of about 25 to about 55 percent.
  • conventional cellulose acetate tow filters within this pressure drop and S.R.E. range have a weight of fiber and plasticizer of about 0. 11 to about 0.16 gram.
  • Compressibility, i.e., resistance to lateral deformation, of the herein described filter is also superior to that of a conventional cellulose acetate tow filter.
  • Conventional tow filters having the above pressure drop, S.R.E. and dimensions have a compressibility of about 30 to about 55 percent.
  • comparable present filters have a compressibility of only about 5 to about 30 percent. In other words, the compressibility of the present filter is about 15 'to about 55 percent of the compressibility of the conventional cellulose acetate tow filters of comparable size and pressure drop and S.R.E.
  • the above superior properties of the present filters are felt to be attributable primarily to the fiber orientation in the filter structure. Testing has shown that approximately 40 to 60 percent of the fibers are aligned within 10 to the perpendicular of the filter axis. Also, the fibers are substantially uniformly disposed across the filter cross section.
  • the above data on fiber orientation was determined by taking micron slices across a filter and cutting strips of 100 microns in width from the filter slice. All the fibers in the section were first counted. Then all fibers having a length greater than 100 microns, i.e., all substantially perpendicular fibers, were counted. From these figures the percent of substantially perpendicular fiberswere calculated. Substantial uniformity across the filter section was determined by taking samples at various angles and comparing the variations in results obtained in thetest procedure, the variation observed to be only minor.
  • a cigarette filter comprising a mass of fibers, the majority of said fibers consisting essentially of very short thermoplastic fibers having a length from about 1 mm. to substantially less than 3 mm. and bonded at their points of contact, 40 to 60 percent of said fibers being aligned within at least i 10 percent of the perpendicular of the axis of said filter and substantially uniformly disposed across the cross section of the filter, said filter when being approximately 8 mm. in diameter and 20 mm. in length exhibiting a pressure drop of 20 to mm. of water, a smoke removal efficiency of from about 25 to about 55 percent, a weight of from about 0.08 to about 0. l4 grams, and a compressibility of from about 5 to about 30 percent.

Landscapes

  • Cigarettes, Filters, And Manufacturing Of Filters (AREA)
US775390A 1968-11-13 1968-11-13 Filter Expired - Lifetime US3656484A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US77539068A 1968-11-13 1968-11-13

Publications (1)

Publication Number Publication Date
US3656484A true US3656484A (en) 1972-04-18

Family

ID=25104259

Family Applications (1)

Application Number Title Priority Date Filing Date
US775390A Expired - Lifetime US3656484A (en) 1968-11-13 1968-11-13 Filter

Country Status (7)

Country Link
US (1) US3656484A (enrdf_load_stackoverflow)
CH (1) CH506959A (enrdf_load_stackoverflow)
DK (1) DK127537B (enrdf_load_stackoverflow)
FI (1) FI50927C (enrdf_load_stackoverflow)
GB (1) GB1258993A (enrdf_load_stackoverflow)
SE (2) SE390596B (enrdf_load_stackoverflow)
ZA (1) ZA697837B (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4059121A (en) * 1973-04-20 1977-11-22 Rothmans Of Pall Mall Canada Limited Filter for tobacco smoke
US4752348A (en) * 1985-03-29 1988-06-21 Celanese Corporation Localized liquid additive applicator system for continuous cylindrical product
US20080314400A1 (en) * 2007-05-31 2008-12-25 Philip Morris Usa Inc. Filter including electrostatically charged fiber material
US20100006112A1 (en) * 2007-12-20 2010-01-14 Philip Morris Usa, Inc. Filter including randomly-oriented fibers for reduction of particle breakthrough
US20110083686A1 (en) * 2009-10-09 2011-04-14 Philip Morris Usa Inc. Method and apparatus for manufacture of smoking article filter assembly including electrostatically charged fibers
US20130231232A1 (en) * 2012-03-05 2013-09-05 Montrade S.R.I. Method and machine for producing paperless filter rods for smoking articles
WO2018215781A1 (en) * 2017-05-24 2018-11-29 Elucid8 Holdings Ltd. Tobacco-containing consumable for aerosol generating devices
CN114190586A (zh) * 2020-09-02 2022-03-18 湖南中烟工业有限责任公司 一种自然增香型减害全颗粒滤棒及其制备方法和应用
CN114786507A (zh) * 2019-12-23 2022-07-22 湖南中烟工业有限责任公司 一种制备全颗粒卷烟/滤棒的设备、方法及制备的全颗粒卷烟/滤棒

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EA201591436A1 (ru) * 2013-03-13 2015-12-30 СЕЛАНИЗ ЭСИТЕЙТ ЭлЭлСи Дымовые фильтры для уменьшения концентрации компонентов в потоке дыма
GB202109084D0 (en) * 2021-06-24 2021-08-11 Nicoventures Trading Ltd Apparatus and methods for manufacturing articles for use as or in an aerosol provision system

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB757841A (en) * 1954-07-02 1956-09-26 Cigarette Components Ltd A method of preparing filter rod and filter rod when prepared by the method
US2805671A (en) * 1953-10-07 1957-09-10 Liggett & Myers Tobacco Co Aerosol filters
US3050430A (en) * 1959-11-12 1962-08-21 Eastman Kodak Co Jet and method of filter manufacture
US3068873A (en) * 1958-11-24 1962-12-18 Celanese Corp Filters
US3225390A (en) * 1959-10-02 1965-12-28 Mueller Paul A Method of producing filter plugs
US3313665A (en) * 1963-06-04 1967-04-11 American Filtrona Corp Method for making fibrous bodies
US3364938A (en) * 1963-12-19 1968-01-23 Eastman Kodak Co Tobacco smoke filter containing porous non-sifting polyolefin particles
US3444863A (en) * 1966-09-21 1969-05-20 Celanese Corp Tobacco smoke filter
US3552400A (en) * 1967-06-08 1971-01-05 American Filtrona Corp Filter plug of staple fiber filter elements and the like

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2805671A (en) * 1953-10-07 1957-09-10 Liggett & Myers Tobacco Co Aerosol filters
GB757841A (en) * 1954-07-02 1956-09-26 Cigarette Components Ltd A method of preparing filter rod and filter rod when prepared by the method
US3068873A (en) * 1958-11-24 1962-12-18 Celanese Corp Filters
US3225390A (en) * 1959-10-02 1965-12-28 Mueller Paul A Method of producing filter plugs
US3050430A (en) * 1959-11-12 1962-08-21 Eastman Kodak Co Jet and method of filter manufacture
US3313665A (en) * 1963-06-04 1967-04-11 American Filtrona Corp Method for making fibrous bodies
US3364938A (en) * 1963-12-19 1968-01-23 Eastman Kodak Co Tobacco smoke filter containing porous non-sifting polyolefin particles
US3444863A (en) * 1966-09-21 1969-05-20 Celanese Corp Tobacco smoke filter
US3552400A (en) * 1967-06-08 1971-01-05 American Filtrona Corp Filter plug of staple fiber filter elements and the like

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4059121A (en) * 1973-04-20 1977-11-22 Rothmans Of Pall Mall Canada Limited Filter for tobacco smoke
US4752348A (en) * 1985-03-29 1988-06-21 Celanese Corporation Localized liquid additive applicator system for continuous cylindrical product
US20080314400A1 (en) * 2007-05-31 2008-12-25 Philip Morris Usa Inc. Filter including electrostatically charged fiber material
US20100006112A1 (en) * 2007-12-20 2010-01-14 Philip Morris Usa, Inc. Filter including randomly-oriented fibers for reduction of particle breakthrough
US9788572B2 (en) 2009-10-09 2017-10-17 Philip Morris Usa Inc. Method and apparatus for manufacture of smoking article filter assembly including electrostatically charged fibers
US8534294B2 (en) 2009-10-09 2013-09-17 Philip Morris Usa Inc. Method for manufacture of smoking article filter assembly including electrostatically charged fiber
US20110083686A1 (en) * 2009-10-09 2011-04-14 Philip Morris Usa Inc. Method and apparatus for manufacture of smoking article filter assembly including electrostatically charged fibers
US10226070B2 (en) 2009-10-09 2019-03-12 Philip Morris Usa Inc. Filter rod including electrostatically charged fibers
US20130231232A1 (en) * 2012-03-05 2013-09-05 Montrade S.R.I. Method and machine for producing paperless filter rods for smoking articles
US9392819B2 (en) * 2012-03-05 2016-07-19 Montrade S.R.L. Method and machine for producing paperless filter rods for smoking articles
WO2018215781A1 (en) * 2017-05-24 2018-11-29 Elucid8 Holdings Ltd. Tobacco-containing consumable for aerosol generating devices
CN110891434A (zh) * 2017-05-24 2020-03-17 艾鲁奇控股有限公司 用于气溶胶产生装置的包含烟草的消耗品
CN110891434B (zh) * 2017-05-24 2022-03-29 艾鲁奇控股有限公司 用于气溶胶产生装置的包含烟草的消耗品
CN114786507A (zh) * 2019-12-23 2022-07-22 湖南中烟工业有限责任公司 一种制备全颗粒卷烟/滤棒的设备、方法及制备的全颗粒卷烟/滤棒
EP3954230A4 (en) * 2019-12-23 2022-11-30 China Tobacco Hunan Industrial Co., Ltd. Device and method for preparing fully granular cigarette/filter rod, and prepared fully granular cigarette/filter rod
CN114190586A (zh) * 2020-09-02 2022-03-18 湖南中烟工业有限责任公司 一种自然增香型减害全颗粒滤棒及其制备方法和应用
CN114190586B (zh) * 2020-09-02 2024-01-19 湖南中烟工业有限责任公司 一种自然增香型减害全颗粒滤棒及其制备方法和应用

Also Published As

Publication number Publication date
DK127537B (da) 1973-11-26
CH506959A (de) 1971-05-15
FI50927C (fi) 1976-09-10
SE390596B (sv) 1977-01-03
SE390595B (sv) 1977-01-03
GB1258993A (enrdf_load_stackoverflow) 1972-01-05
FI50927B (enrdf_load_stackoverflow) 1976-05-31
ZA697837B (en) 1971-06-30

Similar Documents

Publication Publication Date Title
US3819435A (en) Process for making cigarette filters from short synthetic fibers
US3658626A (en) Means for manufacturing staple fiber filter elements
US2881770A (en) Fibrous tobacco smoke filters
US3313306A (en) Stable elongated elements and smoking means incorporating the same
US3804695A (en) Apparatus for making tobacco smoke filters
US2794239A (en) Tow for use in the production of tobacco smoke filters
US4807809A (en) Rod making apparatus for smoking article manufacture
US2794480A (en) Apparatus for the manufacture of filters composed of cellulose acetate
EP0568107B1 (en) Method and apparatus for forming a rod for use in the manufacture of smoking articles
US3648711A (en) Tobacco smoke filter
US3144025A (en) Tobacco smoke filters
UA67876C2 (uk) Високоефективний сигаретний фільтр
US2966157A (en) Polyolefin tobacco smoke filters
US3390039A (en) Method and apparatus for making additive filters
US4007745A (en) Filter
US3224453A (en) Filter cigarettes
US3656484A (en) Filter
US3377220A (en) Process for making stable elongated elements
US3079930A (en) Process and apparatus for manufacturing filters
US4366826A (en) Smoke filtration
US4189511A (en) Filter
EP0196867A2 (en) Localized liquid additive application system for continuous cylindrical product
US3106501A (en) Process for manufacturing filters
US3852009A (en) Filter making apparatus
US3079978A (en) Apparatus for manufacturing filters