Abstract:
A smoking article having a filter segment that establishes both a desired resistance to draw and a mixing of mainstream smoke with ventilation air. The filter segment includes a fluted portion, a frusto-conical portion and axially extending orifices establishing fluid communication between the frusto-conical portion and voids between one or more walls of the fluted portion.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) to U.S. provisional Application No. 60/836,144, filed on Aug. 8, 2006, the entire content of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention relates to ventilated cigarettes, ventilated cigarette filters and methods of making same. 
     SUMMARY 
     A smoking article having a filter segment that establishes both a desired resistance to draw and a mixing of mainstream smoke with ventilation air. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional side cut-away view of a preferred embodiment, with the tipping paper having been partially unraveled. 
         FIG. 2  is a perspective view of a preferred embodiment, with some internal features of the filter shown with dashed-lines. 
         FIG. 3  is a representation of a method of manufacturing the cigarette and filter of the preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A preferred embodiment provides a smoking article  10  comprising a tobacco rod  12  and a filter  14  which are joined together by a tipping paper  16 . 
     The filter  14  comprises a first filter segment  20  adjacent the tipped end  21  of the tobacco rod  12 . Preferably, the first filter segment  20  is constructed of a fibrous cellulose acetate (CA) tow or a plug of cellulose acetate tow laden with activated carbon particles (COT), beads or other absorbents. 
     The filter  14  further comprises a second filter segment  22  in downstream relation to the first segment  20  (in the sense of direction that mainstream smoke is drawn through the filter  14  during a puff). The second filter segment  22  includes a hollow frusto-conical upstream portion  24  and a fluted downstream portion  26 . The fluted downstream section can include one or more planar or non-planar walls defining voids  28 . The diameter of the second filter segment  22  is approximately equal to that of the filter  14 , such that the outer peripheries of portions  24 ,  26  and any (optional) plug wrap  29  are adjacent (abut) the tipping paper  16 . The second filter segment  22  further includes one or more, preferably at least 2 orifices  34  at locations about the frusto-conical portion  24  that communicate the interior space  25  of the upstream frusto-conical portion  24  with one or more of the flutes (or “voids”)  28  defined between the downstream fluted portion  26  and adjacent portions of a plug wrap  29  and/or the tipping paper  16 . 
     Preferably, the filter  14  further comprises a mouthpiece filter segment  30  at the buccal end of the filter  14  and one or more rows of ventilation holes  32 . The ventilation holes  34  are at a location along the filter  14  downstream of the orifices  34  and preferably are in superposed relation to the flutes (“voids”)  28  of the downstream segment portion  26 . 
     During a puff on the cigarette  10 , mainstream smoke is drawn from the tobacco rod  12  into the filter  14  through the first segment  20  and then into the space  25  and through the orifices  34  of the upstream portion  24  of the second filter segment  22 . Upon entering the flutes  28  of the downstream segment portion  26 , the mainstream smoke is mixed with ventilation air that is drawn through the ventilation holes  32 . The ventilated mainstream smoke is then drawn through the mouthpiece filter and out the cigarette  10 . 
     In the preferred embodiment, the downstream filter segment is formed to establish four (4) flutes  28 , whereas three (3), two (2) or one (1) flutes might be arranged instead ( 28 ′,  28 ″ in  FIG. 3 ). More than four flutes are also a possibility. 
     A preferred material for construction of the second filter segment  22  is a heavy wrapping paper such as non-permeable 0.006 inch thick paper similar to that used in a Parliament recessed filter cigarette or stiff porous plug wrap. However, other materials may be used such as polyethylene, polypropylene and the like, non-woven stable fibers, and/or extruded open-celled foamed material, e.g., cellulose acetate filamentary tow material. For example, the second filter segment can be made from high density polyethylene and/or polypropylene. 
     The first filter segment  20  prevents tobacco particles and the like from clogging the orifices  34  of the second filter segment  22 . Preferably, it is constructed of cellulose acetate tow of low particulate efficiency, e.g., cellulose acetate tow of 8.0 denier per filament and 35000 total denier. 
     The mouthpiece filter segment  30  is preferably constructed from cellulose acetate tow and is of low particulate efficiency, e.g., cellulose acetate tow of 8.0 denier per filament and 35000 total denier. 
     The ventilation holes  32  are preferably laser perforations made by known online laser perforation techniques. However, pre-perforated tipping paper can also be used. 
     The orifices  34  may be located and aligned relative to the flutes  28  such that they promote mixing of mainstream smoke with ventilation air along the flutes  28 . Referring now to  FIG. 2 , in addition or in the alternative, the orifices  34  may be arranged to direct mainstream smoke toward adjacent surface regions  125  of the downstream fluted portion such that impaction of mainstream smoke is promoted to thereby remove a larger contingent of particles of tar from the mainstream smoke and to increase smoke particle filtration efficiency under higher flow rate or larger puff volume. 
     The cigarette  10  and the layout of its filter  14  are conducive to high speed manufacturing techniques including those taught in U.S. Pat. No. 4,357,950, hereby incorporated by reference in its entirety. 
     Referring now to  FIG. 3 , a method of manufacturing the cigarette  10  includes production of a continuous hollow tube  50  which is fed through a set of crimping wheels  54  whose perimeters form at their nip the aforementioned downstream fluted portions  26  of the second filter segments  22 . Optionally, a plug wrap  29  can be added using a garniture  56  or other expedient. A laser  58  is employed to establish the orifices  34  at location(s) about the frusto-conical portion  24  of the second filter segment  22 . A knife  60  severs the continuous, crimped rod into 2-up plugs of second filter segments  22 ,  22 ′, which are combined with 2-up plugs of first filter segments  20 ,  20 ′, which are severed in the middle of the 2-up second filter segments  22 ,  22 ′ and combined with 2-up plugs of mouthpiece filter segments  30 ,  30 ′ to form 2-up filters  14 ,  14 ′. Pairs of tobacco rods  12 ,  12 ′ are tipped with 2-up filters  14 ,  14 ′ and tipping paper  16  to form 2-up cigarettes, which are severed and laser perforated to establish ventilation holes  32 . 
     The order of the aforementioned steps of manufacture may vary. 
     Preferably, the size of the orifices  34  can range from 0.4 to 0.8 mm in diameter and are sized to produce a desired range of resistance to draw, e.g., at least 50 mm water or greater, preferably 60 to 90 mm water, measured at a flow rate of 1050 cc/min; whereas the ventilation holes  32  are of such size and number so as to produce ventilation in the range of approximately 45 to 90%, more preferably in the range of approximately 50 to 80%. 
     With such filter and cigarette construction, there is achieved a mass-producible filter and smoking article of elevated ventilation with acceptable levels of RTD and with desirable organoleptic qualities of its smoke. 
     In another embodiment, when the second filter segment is constructed of polyethylene, polypropylene, and the like, the second filter segment can be fabricated using injection molding in either individual pieces or in multiples of 2, 4 or 6 (2-up, 4-up or 6-up) instead of the continuous process using a crimping wheel. The 2-up, 4-up or 6-up second filter segments fabricated by injection molding can be wrapped in a plug wrap of desired thickness and mechanical strength when combined with the upstream and/or downstream plugs of filter material such that the outer peripheries of the frusto-conical portion and the fluted portion and any optional plug wrap are adjacent the tipping paper. 
     The preferred embodiments are merely illustrative and should not be considered restrictive in any way. The scope of the invention is given by the appended claims, rather than the preceding description, and all variations and equivalents which fall within the range of the claims are intended to be embraced therein.