Patent Publication Number: US-8113215-B2

Title: Smoking article filter having liquid additive containing tubes therein

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) to U.S. provisional Application No. 60/929,319, filed on Jun. 21, 2007, the entire content of which is incorporated herein by reference. 
    
    
     SUMMARY 
     Smoking articles are provided that include filters having at least one liquid additive containing tube therein. Preferably, the additive containing tubes hold additives that are contained therein by a barrier. In a preferred embodiment, the barrier includes at least one liquid layer that disperses when a puff of a smoking article is taken to release the enclosed additive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of a smoking article including a filter containing an additive containing tube. 
         FIG. 2  is an illustration of a smoking article including a filter containing an additive containing tube and a sorbent. 
         FIG. 3  is an illustration of a smoking article including a filter containing multiple additive containing tubes. 
         FIG. 4  is an illustration of an additive containing tube of a preferred embodiment. 
         FIG. 5  is a cross-sectional view of the additive containing tube of  FIG. 2 . 
         FIG. 6  is an illustration of an additive containing tube of a preferred embodiment. 
         FIG. 7  is an illustration of an additive containing tube of a preferred embodiment. 
         FIG. 8  is an illustration of an additive containing tube of a preferred embodiment. 
         FIG. 9  is an illustration of a smoking article including a filter containing an additive containing tube. 
         FIG. 10  is an illustration of a smoking article including a filter containing an additive containing tube. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, the “upstream” and “downstream” relative positions between filter segments and other features are described in relation to the direction of mainstream smoke as it is drawn from the tobacco rod and through the multi-component filter. 
     Referring now to  FIG. 1 , in a preferred embodiment, a smoking article  10  includes a tobacco rod  12  and a filter  14 . Preferably, the filter  14  includes at least one impervious, additive containing tube  24  located between a mouth end filter segment  20  and an upstream filter segment  22 . Preferably, the additive containing tube  24  is disposed in a filter material  36 . Preferably, the filter material  36  comprises a hollow acetate tube, a plug of cellulose acetate tow, a plug of carbon on cellulose acetate tow, filter paper, a body of porous adsorbent, and/or an impervious solid. 
     In a preferred embodiment, the impervious tube  24  contains at least one liquid additive  26 . In a preferred embodiment, the additive  26  is a flavorant, such as a liquid flavorant. Preferably, the additive  26  is held in the tube  24  by at least one barrier layer  28 . Also preferably, the additive  26  is held in the tube  24  by at least one barrier layer  28  at each end of the tube  24 . Preferably, the at least one barrier layer is a liquid barrier layer. Also preferably, liquid barrier layers are placed away from the ends of the tube to prevent removal of the liquid barrier by contact with other materials via capillary action, wetting, and/or other phenomena during filter making and cigarette making operations. 
     A second barrier  30  may also be included. In an embodiment, the second barrier layer  30  comprises wax, films, gels, and/or emulsions. When a puff is drawn upon the filter  14 , the barriers  28 ,  30  are caused to scatter, break and/or contract and the enclosed additive  26  is dispersed into the filter material, making the additive readily available upon its release from the tube  24  and during subsequent puffs. In an embodiment, the film and gel barrier layers are chosen to have an acceptable fluidity, such that when a puff is taken, the film or gel breaks and the additive is dispersed into the mouthend filter segment  20 . 
     In a preferred embodiment, as seen in  FIG. 2 , the additive containing tubes  24  are used in smoking articles  10 , along with optional sorbents  40 . The sorbent, such as microporous materials, can be used to filter or remove gas phase constituents from cigarette smoke. Sorbents (i.e., microporous sorbents) such as an activated carbon, silicas, zeolites and the like can be used. 
     While any suitable material can be used as a sorbent, a preferred sorbent includes activated carbon. However, sorbents present challenges to a cigarette designer&#39;s ability to add materials, such as volatile flavor components like menthol, as the sorbents may adsorb and/or absorb migrating volatile compounds during the time between cigarette manufacture and use. 
     Two problems occur when additive materials, such as volatile flavor components, are included in smoking articles with sorbents: first, the additive materials can migrate (dissipate) throughout the smoking article during storage; and second, the additive materials can be adsorbed or absorbed by the sorbents during smoking. 
     When additive materials are adsorbed and/or absorbed by sorbents, not only can additive materials be lost, but also the additive materials can occupy active sites in the sorbent. If the additive materials occupy active sites in the sorbent, the ability of the sorbent to remove targeted gases or constituents from smoke can be compromised. Additive containing tubes  24  can be used to overcome this problem by containing and isolating the additive materials  26  from the sorbent  40  prior to smoking, therefore avoiding interaction between the additive materials  26  and the sorbent  40  during storage (shelf-life). 
     In a preferred embodiment, a molecular sieve material can also be present in the filter  14 . Preferably, the molecular sieve material can be present in monolithic or cavity filled particle form sized at about 0.1 mm to 1 mm, and more preferably 0.3 mm to about 0.9 mm (e.g., 0.3 mm to 0.4 mm, 0.4 mm to 0.5 mm, 0.5 mm to 0.6 mm, 0.7 mm to 0.8 mm or 0.8 mm to 0.9 mm) to facilitate processing into cigarette filters so as to achieve a desirable filter pressure drop or RTD (resistance to draw). 
     Various filter constructions known in the art can be used, in which additive containing tubes  24  can be incorporated. Exemplary filter structures that can be used include, but are not limited to, a mono filter, a dual filter, a triple filter, a single or multi cavity filter, a recessed filter, a free-flow filter, combinations thereof and the like. Filter elements are typically constructed from cellulose acetate tow or cellulose paper materials. 
     Referring now to  FIG. 2 , in an embodiment, the smoking article includes a tobacco rod  12  and a filter  14  joined together by tipping paper  15 . Preferably, the filter  14  includes at least one impervious additive containing tube  24  and a sorbent  40 . Preferably, the sorbent  40  is located upstream of the additive containing tube  24 . As sorbents can adsorb or absorb additives such as a flavorant, placing the sorbent  40  upstream from the flavorant in the additive containing tubes  24  can reduce the level of absorption or adsorption of the flavorant by the sorbent  40  during smoking. 
     Preferably, the additive containing tubes  24  can be located in a portion of the filter  14  downstream from the sorbent  40  with a section of filter material  70 , such as cellulose acetate, therebetween. Preferably, the additive containing tubes  24  and the sorbent  40 , if provided, would be placed in cavities within a filter  14 . However, both the additive containing tubes  24  and the sorbent  40 , if provided, can be placed elsewhere within a filter  14  of a smoking article  10 . 
     Regardless of the type of smoking article in which the additive containing tubes  24  is incorporated, the additive containing tubes  24  can be used to provide effective containment and delivery of materials, such as volatile flavors or other smoking related additives. 
     Referring now to  FIG. 3 , in a preferred embodiment, a smoking article  10  can include multiple additive containing tubes  24 , each containing the same or different additive  26 . Most preferably, a filter  14  contains 1 to about 5 tubes  24 . More preferably, the filter  14  contains 1 to about 3 tubes  24 . 
     Referring now to  FIG. 4 , in a preferred embodiment, the additive containing tubes  24  are preferably impervious tubes having lumens  32  capable of containing an additive  26 . Preferably, the additive  26  is maintained within the impervious tube  24  by a first barrier layer  28  and optionally a second barrier layer  30 . If desired, additional barrier layers can be included. Preferably, the first barrier layer  28  and the second barrier layer  30  are located upstream and downstream of the additive  26  within the tube  24 . 
     Preferred additive containing tubes  24  are made of glass, polymers, cellulose base, and/or metal, such as, but not limited to polyethylene terephthalate, polysulfone, polyimide, Teflon, polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene (FEP), polyetheretherketone (PEEK), silicon elastomer, and/or glass. Most preferably, the additive containing tubes  24  are glass. However, due to the fragility of glass, other materials, with or without additional coating to make the material more mechanically robust and/or impervious, are also suitable. 
     The impermeable additive containing tube can include a permeable tube wall  34  having a coating  56  to prevent loss of the additive  26  through the tube walls  34 . For example, permeable polymer tubes may include a coating  56  of wax that is applied by heating the wax, applying the wax to the walls  34  of the tube  24 , and then cooling the coated tube  24 . Paraffin, silicon rubber and/or epoxy can also be used as a coating material. Glass tubes  24  typically do not require a coating  56  since glass is impervious. Preferably, the coating is about 0.01 mm to about 1.0 mm thick. 
     In a preferred embodiment, the tubes  24  have a lumen diameter of about 0.5 mm to about 2.5 mm, more preferably about 0.8 mm to 1.4 mm and most preferably about 0.9 mm to about 1.2 mm. If the diameter is too small liquid flavorant or any other liquid additive may not be withdrawable from the tubes  24  by drawing action during a puff. However, if the diameter is too large, the additive may not be retained in the tube because the capillary forces needed to hold both the additive and the liquid barrier in place may be insufficient. In accordance with a preferred embodiment, it is desirable to create a balance between delivery via puffing and the ability to retain an additive in a tube. Thus, the inner diameters of the additive containing tubes are preferably sized to optimize the additive containing tubes&#39; ability to releaseably contain additive materials. 
     The liquid additive  26  is held within the tube  24  by capillary action and/or surface interaction, and preferably the liquid is releaseably maintained in the tubes by at least one barrier layer. Preferably, the additive containing tube  24  includes a first barrier layer  28  and a second barrier layer  30 . Also preferably, the first barrier layer  28  is immiscible with the additive  26  and has a low solubility for the additive. As a result, the barrier layer prevents the additive from dissolving in the barrier layer and diffusing out of the additive containing tube  24 . The second barrier layer  30  is added to prevent the release of the additive and loss of the first barrier layer. Preferably, the second barrier layer is chosen to have a low vapor pressure. Depending on the additive, additional barrier layers may be used. Preferably, each barrier layer is about 0.5 mm to about 2 mm thick. 
     EXAMPLE 1 
     Five micro-liters (5 μl) of 25% menthol in vegetable oil is injected into a 0.8 mm to 1 mm glass tube that is about 15 mm long. Then, about 1 mm to about 2 mm or water is injected at both ends of the tube to sandwich the flavor liquid and form a barrier. About 1 mm to about 2 mm of vegetable oil with 50% hydrogenated oil is injected at each end to form a second barrier layer. 
     EXAMPLE 2 
     5 μl of 25% menthol in vegetable oil is injected into a 0.8 mm to 1 mm inner diameter glass tube that is about 15 mm long. Then, a layer of about 1 mm to about 2 mm or water is injected at both ends of the tube to sandwich the flavor liquid and form a barrier. A layer of about 1 mm to about 2 mm of 3% wax in vegetable oil is injected at each end to form a second barrier layer. 
     Preferably, the following formula approximates the thickness of each liquid barrier layer based on the surface tension of the additive and the inside diameter of the tube:
 
 h= 2τ cos θ/ρ rg  
 
where τ is the surface tension of the liquid additive, ρ is the density of the liquid additive, θ is the inner radius of the tube, θ of the angle between the surface and the liquid additive (contact angle), g is the gravitational acceleration and h is the height of the fluid rise in the tube.
 
     In a preferred smoking article, additive containing tubes  24  are oriented in a direction in which smoke will travel through the smoking article  10 . By providing such alignment, when a puff is taken, the barrier is displaced due to draw pressure to release the additive from the additive containing tube  24  and smoke can travel through lumens  32  of the additive containing tubes  24  in a direction approximately parallel to the suction or vacuum force applied at the downstream end of the smoking article drawing smoke from the upstream or lit end. 
     Additionally, when incorporating multiple additive containing tubes  24 , the tubes  24  are preferably approximately parallel to the one another in order to allow smoke to evenly pass through the lumens  32  of the tubes  24 , and for fitting bundles of tubes  24  into the axis of a filter for a smoking article when multiple additive containing tubes  24  are desired. 
     The additive containing tubes  24  can be used within any smoking article, such as a cigar and a traditional or less-traditional cigarette, e.g., in a cigarette filter. Less-traditional cigarettes include, by way of example, cigarettes for use with electrical smoking systems as described in commonly-assigned U.S. Pat. Nos. 6,026,820; 5,988,176; 5,915,387; 5,692,526; 5,692,525; 5,666,976; 5,345,951; 4,991,606; 4,966,171 and 5,499,636, the disclosures of which are hereby incorporated by reference herein in their entireties. 
     Additive containing tubes  24  are preferably sized to a length less than the length of a filter  14  so that the entire length of the tube can fit within the area of the filter  14  as the additive containing tubes  24  are aligned in the direction of smoke flow. Also, the diameters of the lumens  32  (space within the tube) of the additive containing tubes  24  (in combination with the material used to make the additive containing tubes and the density of any bundle of additive containing tubes) control the amount of flow possible, as well as the force required to pull the tobacco smoke through the filter (hereinafter, resistance to draw (RTD)). The smoke can travel through the lumens  32  and/or around the exterior of the tubes  24 . 
     Preferred embodiment additive containing tubes  24  are used to releasably hold additive materials within the lumens  32  of the additive containing tubes  24 . Thus, because of the releasable hold, additive materials  26  in the additive containing tubes  24  can be sufficiently contained to substantially avoid or minimize unwanted migration of the additive materials, such as, for example, during shipping, storage and shelf-life at retail of the smoking articles with the additive materials therein. 
     Therefore, in a typically-sized cigarette (e.g., a cigarette with a length between 65-100 mm, a diameter of 6-9 mm and a filter length of 15-30 mm), the additive containing tubes can have a lumen (i.e., inner) diameter of approximately 0.5 millimeters (mm) to approximately 2.0 mm (e.g., 0.5-1.0, 1.0-1.5, 1.5 to 2.0 mm), preferably approximately 0.8 mm to approximately 1.4 mm, and most preferably approximately 0.9 mm to approximately 1.2 mm. 
       FIG. 5  is a cross-sectional view of an additive containing tube  24  showing the lumen  32  and the outer wall  34  thereof. 
     In an exemplary embodiment, a filter for a cigarette can be designed to include a bundle of 1 to 5 additive containing tubes (e.g., 1 to 3, 2 to 4, 3 to 5 or 2 to 3). Preferably, each additive containing tube therein has a lumen diameter of approximately 0.9 mm to approximately 1.2 mm, a wall thickness of approximately 50 microns. 
     In order to use the additive containing tubes  24  in a smoking article, the additive containing tubes  24  are cut or otherwise made to a specific length. The additive containing tubes  24  can preferably be used in a circumferentially spaced relation in a filter section of a smoking article or can be gathered into a bundle prior to insertion into a final product. If the additive containing tubes are bundled, the additive containing tubes  24  can be held together using a permeable, semi-permeable or impermeable material, such as a potting material, an enclosure, such as a ring, or an adhesive, such as triacetin, epoxy, and silicone rubber. 
     Additive containing tubes  24  can also be incorporated into a cigarette filter to provide a means for controlling a resistance to draw (RTD) in a cigarette. In a preferred embodiment, a cigarette filter would include additive containing tubes  24  therein. By providing additive containing tubes in a cigarette, a cigarette can be provided with as little or as much resistance to draw as desired. 
     Additionally, additive containing tubes  24  can be used to supplement or replace multi-section filter assemblies, which are often more difficult to manufacture than additive containing tubes  24 . Thus, additive containing tubes  24  in cigarette filters could be used to simplify the manufacturing process while still providing tailored levels of RTD. 
     Referring now to  FIGS. 6 ,  7 , and  8 , in an embodiment, the tube  24  can be designed to improve the ability of the tube to contain the additive  26  under severe shaking or vibrations that may occur during shipment. While the barrier layer  28  can contain the additive  26  when stored, when shaken, the barrier  28  may disperse and release the additive  26 . Thus, the tubes  24  may include multiple chambers  50 , as seen in  FIG. 6 , and/or curved channels leading to orifices  52 , as seen in  FIG. 8 , so as to help secure the additive within the tube. In an embodiment, as seen in  FIG. 7 , the tube  24  includes an elongated channel  54  leading to an orifice. 
     Additive containing tubes can desirably be used to contain additives in a smoking article. Preferably, the additives are protected from loss during shipment and storage so as to maintain freshness of the product. 
     The additive containing tubes  24  can preferably be placed in a smoking article  10 , more preferably a cigarette filter  14 , where the additive containing tubes  24  are aligned in a cigarette for airflow. For example, the long axes of the additive containing tubes  24  can be aligned with the long axis of the cigarette for airflow purposes. 
     The additives can be flavorants, which can be selected from any number of known artificial and natural materials, such as, for example, peppermint, spearmint, wintergreen, menthol, eugenol, cinnamon, chocolate, coffee, tobacco, vanillin, licorice, clove, anise, sandalwood, geranium, rose oil, vanilla, lemon oil, cassia, spearmint, fennel, ginger, ethylacetate, isoamylacetate, propylisobutyrate, isobutylbutyrate, ethylbutyrate, ethylvalerate, benzylformate, limonene, cymene, pinene, linalool, geraniol, citronellol, citral, peppermint oil, orange oil, coriander oil, borneol, fruit extract and the like. Illustrative of such tobacco flavorants are those described in U.S. Pat. Nos. 3,580,259; 3,625,224; 3,722,516; 3,750,674; 3,879,425; 3,881,025; 3,884,247; 3,890,981; 3,903,900; 3,914,451; 3,915,175; 3,920,027; 3,924,644; 3,966,989; 4,318,417; and the like, which are incorporated herein by reference in their entirety. 
     The additives can also be chemicals, such as chemicals used to attract or repel aerosols, chemicals that react with smoke constituents to remove or chemically extract smoke constituents, solvents, surfactants, anti freezing agents and/or stimuli responsive polymers or gels. 
     In an embodiment, as shown in  FIG. 9 , the filter  14  can include a tube  24  located near the tobacco rod  12 . The tube  24  can include a first barrier layer  28  and/or a second barrier layer  30 . The barrier layers  28 ,  30  at an upstream end of the tube  24  can be formed of a heat sensitive material that melts or otherwise dissipates when heated, such that the additive is released when the barrier layer  28 , is heated. The downstream layers  28 ,  30  can be liquid barriers, as described above. After the upstream barrier layer  28 ,  30  melts, the user takes a puff, which then causes both the downstream puff activated liquid barrier layers  28 ,  30 , formed as described above, and the upstream heat activated barrier layers  28 ,  30  including the melted heat sensitive material to dissipate and the additive  26  to be released from the tube  24 . In an embodiment, the first barrier layer  28  at the upstream end of the tube can be a liquid barrier layer and the second barrier layer  30  can be a heat sensitive barrier layer. 
     Preferably, the upstream end of the tube  24  lies within the filter  14  about 0.01 mm to about 3.0 mm away from the downstream end of the tobacco rod  12 . Once the tobacco rod  12  has burned nearly to the filter  14 , the barrier layer  28 , formed of the heat sensitive material heats up and melts. Thus, when the cigarette has nearly completely burned, the additive  26  is released from the tube  24  having the barrier layer  28 ,  30  formed of the heat sensitive material. For example, the sealant at the upstream end of the tube can be a thermally responsive material which is solid or semi-solid at ambient temperature and free flowing at 50 to 80° C. The sealant at the downstream end of the tube can be a liquid. As the burning tobacco gets closer to the upstream end of the tube, heat from the burning tobacco causes the upstream sealant to become free flowing thereby allowing liquid flavorant in the tube to spread into surrounding filter material and release flavor into mainstream smoke during remaining puffs. 
     The heat sensitive material can be selected from the group consisting of wax, paraffin, glycerol, a mixture of polymers and combinations thereof. Preferably, the heat sensitive material melts when exposed to temperatures of about 60° C. to about 90° C. The polymers and other heat sensitive materials can be selected so that the melting point thereof falls within the preferred range. 
     In a preferred embodiment, the heat sensitive material is a mixture of beeswax in vegetable oil. Preferably, the mixture includes about 7% to about 20% beeswax in vegetable oil based on the volume of the mixture. Such mixtures are semi-solid or solid at ambient temperature and melt when exposed to heat. Mixtures including lower amounts of beeswax are in liquid form at ambient temperature and thus will not form a solid barrier  28 ,  30  that melts in response to heat provided by the burning tobacco rod  12 . 
     Table 1 compares when the delivery of additive occurred during smoking from cigarette filters including 20 mm long, 1.45 mm internal diameter polyimide tubes  24  having an upstream barrier including 7% beeswax in vegetable oil, 15% beeswax in vegetable oil or 17% beeswax in vegetable oil. The cigarettes were puffed under FTC conditions. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 Additive 
                 Additive 
                 Additive 
               
               
                   
                 Barrier 
                 Delivered 
                 Delivered 
                 Not 
               
               
                   
                 Layer 
                 Before Last Puff 
                 At Last Puff 
                 Delivered 
               
               
                   
               
             
            
               
                   
                 7% beeswax 
                 6 out of 
                 2 out of 
                 none 
               
               
                   
                 in oil 
                 8 samples 
                 8 samples 
                   
               
               
                   
                 15% beeswax 
                 0 out of 
                 3 out of 
                 none 
               
               
                   
                 in oil 
                 3 samples 
                 3 samples 
                   
               
               
                   
                 17% beeswax 
                 0 out of 
                 1 out of 
                 3 out of 
               
               
                   
                 in oil 
                 4 samples 
                 4 samples 
                 4 samples 
               
               
                   
               
            
           
         
       
     
     As shown in Table 1, tubes including a barrier layer including 15% beeswax in oil more consistently released the additive at last puff as desired. In contrast, tubes including a barrier layer of 7% beeswax in oil were more likely to prematurely release the additive. Tubes including 17% beeswax in oil were more likely to fail to deliver the additive. Thus, in a most preferred embodiment, the barrier layer includes about 12% to about 16% beeswax in oil. 
     In another embodiment, as shown in  FIG. 10 , the filter can include tubes  24  that are puff activated  100  and tubes that are heat activated  101 . The tubes  24  can be in a staggered relationship such that the tubes  24  having an upstream heat sensitive barrier layer  28 ,  30  are located closer to the tobacco rod  12 . The tubes  24  without heat sensitive barrier layers  28 ,  30  release the additive  26  from the tube  24  in response to drawing action during a puff on the cigarette. Additional additives  26  are later released from the tubes  24  having the heat sensitive barrier layers  28 ,  30  when the cigarette tobacco rod  12  has almost completely burned. Thus, the additives  26  can be delivered from the tube  24  at various times throughout the use of the cigarette. 
     In this specification, the word “about” is often used in connection with numerical values to indicate that mathematical precision of such values is not intended. Accordingly, it is intended that where “about” is used with a numerical value, a tolerance of 10% is contemplated for that numerical value. 
     While the invention has been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made, and equivalents employed, without departing from the scope of the appended claims.