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
  • A24D3/06—Use of materials for tobacco smoke filters
  • A24D3/16—Use of materials for tobacco smoke filters of inorganic materials
• • 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
• • 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
  • A24D3/06—Use of materials for tobacco smoke filters
• • 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
  • A24D3/06—Use of materials for tobacco smoke filters
  • A24D3/16—Use of materials for tobacco smoke filters of inorganic materials
  • A24D3/163—Carbon

Definitions

• the present invention relates to tobacco smoke filters, especially for cigarettes.
• Activated carbon is a strong adsorbent; it is effective in removing a large number of these compounds from tobacco smoke.
• the compounds in the VP fraction all tend to be reduced by activated carbon to a similar extent; activated carbon may be described as an effective "blanket adsorbent”.
• HCN hydrogen cyanide
• a tobacco smoke filter containing a high activity activated carbon impregnated with a metal impregnant.
• the metal impregnant is present in an amount which is up to 10% of the dry weight of the high activity activated carbon. More preferably the impregnant is present in an amount which is from 1 to 5% of the high activity activated carbon.
• the metal impregnant may be, for example, one or more of copper, manganese, molybdenum, cobalt, iron, zinc. In one preferred embodiment, the impregnant is copper. In another preferred embodiment the metal impregnant is a combination of copper and molybdenum.
• metal impregnant in any form (e.g. salts, complexes, chelates etc.).
• the activated carbon of the invention may be derived from any raw material for which it is possible to prepare an activated carbon [these raw materials from which activated carbons may be prepared include, for example, wood, coal, nutshell such as coconut, peat, petroleum coke and bone; and synthetic sources such as poly (acrylonitrile) or phenol-formaldehyde] .
• the activated carbon is a "high activity” activated carbon.
• Activity in this context refers to percentage by weight of a particular vapour (e.g. carbon tetrachloride - CTC) adsorbed under equilibrium conditions by the base activated carbon (the base activated carbon refers to the activated carbon prior to impregnation by impregnant e.g. copper and/or molybdenum) .
• Levels of activity herein are given as %CTC values.
• a value of carbon activity of 95%CTC refers to a level of adsorption of 95% by weight of CTC under equilibrium conditions.
• High activity refers to a base activated carbon (that is, an activated carbon prior to metal impregnation) which adsorbs more than about 90% CTC under equilibrium conditions.
• the activity is greater than 90% prior to impregnation.
• the activity of the activated carbon is greater than 100% prior to impregnation (that is, the base activated carbon adsorbs more than about 100% CTC under equilibrium conditions) .
• the activated carbon has an activity of greater than 80% CTC, more preferably greater than 90% CTC, after impregnatio .
• a tobacco smoke filter containing activated carbon which is impregnated with copper and molybdenum, wherein the ratio of copper to molybdenum is greater than 1.3 to 1.
• a preferred ratio of copper to molybdenum (by weight) in the impregnated activated carbon is greater than 2:1. Particularly preferred are ratios of between 3.5:1 and 4.5: 1. A particularly preferred ratio of copper to molybdenum in the impregnated activated carbon is 4:1.
• the activated carbon is a high activity activated carbon.
• a tobacco smoke filter containing activated carbon which is impregnated with copper and molybdenum, wherein the activated carbon is a high activity activated carbon.
• the activity of the activated carbon is greater than 90% CTC, more preferably greater than 100% CTC.
• the copper and molybdenum are present in a combined amount which is not more than 10% of the dry weight of the activated carbon.
• the copper and molybdenum are present in the activated carbon in an amount which is from 1 to 5% of the dry weight of the activated carbon.
• the ratio of copper to molybdenum is greater than 1.3 to 1. More preferably, the ratio of copper to molybdenum is greater than 2 to 1, preferably between 3.5 to 1 and 4.5 to 1. A particular preferred ratio of copper to molybdenum is 4 to 1.
• the particle size of the activated carbon of the invention depends on the performance required and the filter configuration. In the specification mesh sizes given are US Mesh. Suitable impregnated activated carbon is of particle size between 2mm (mesh size 10) and 0.15mm (100 mesh) . Preferably, substantially all of the impregnated activated carbon is of particle size between 0.6mm (30 mesh) and 0.212mm (70 mesh) . More preferably, substantially all of the impregnated activated carbon is of particle size between 0.425mm (40 mesh) and 0.212mm (70 mesh) .
• the impregnated activated carbon of tobacco smoke filters according to the invention may display surprising selective removal of HCN without detrimental effect on overall VP reduction. Impregnated carbons have not previously found favour in cigarette applications because chemical reactions between the impregnated component (e.g. metal ion) and components present in smoke (and/or the products of these reactions) have a detrimental effect on the taste of the cigarette which reduces smoker satisfaction.
• the tobacco smoke filters of the invention may include a rather lower amount of e . g. impregnated copper, impregnated copper and molybdenum than previously thought necessary for acceptable removal of HCN; this is likely to reduce any adverse effects on taste.
• Preferred tobacco smoke filters contain less than 150mg activated carbon impregnated with metal impregnant (e.g. copper and molybdenum).
• metal impregnant e.g. copper and molybdenum.
• Particularly preferred tobacco smoke filters contain from lOmg to 70mg impregnated activated carbon, more preferably 30mg to 60mg impregnated activated carbon.
• the filter according to the invention may be of any design previously proposed for particulate adsorbent - containing tobacco smoke filters.
• the impregnated activated carbon according to the invention may be dispersed throughout the filter plug, carried on the tow or fibres or sheet material which is gathered to form the plug; it may instead adhere to one or more threads which extend through the matrix of the filter plug or be adhered to the inner face of a wrapper around the filter plug (as described for example in GB-A-9124535 and GB-A-9221545, to which attention is directed for more information) ; or it may form a bed sandwiched between a pair of plugs (e.g. of cellulose acetate tow) in a common wrapper.
• a pair of plugs e.g. of cellulose acetate tow
• Filters according to the invention may additionally include one or more particular adsorbents other than the activated carbon required by the invention (e.g. silica gel, a different activated carbon or zeolite) , which may or may not selectively remove other compounds present in the VP fraction of cigarette smoke (e.g. aldehydes).
• the additional adsorbent (s) may be mixed with the activated carbon required by the invention and/or separated from this .
• Tobacco smoke filters according to the invention may also provide efficient removal of HCN even after prolonged periods (e.g. in storage) following filter or cigarette manufacture.
• the carbon used in known filters adsorbs volatile species present in the filter or tobacco during storage, thereby reducing the efficiency with which the filter carbon can remove VP compounds when the cigarette is smoked. This has the result that the efficiency with which the known filters remove HCN also decreases on ageing.
• the ability of filters according to the invention to remove HCN does not deteriorate significantly even after storage for prolonged periods (e.g. six months) .
• the present invention also provides a filter cigarette comprising a filter according to any preceding claim joined at its upstream end to a wrapped tobacco rod.
• the cigarette filter according to the invention will usually be attached to a wrapped tobacco rod with conventional tipping overwrap, which may be a ventilated or non-ventilated overlap.
• Figs. 1 and 2 respectively are schematic sectional side elevation views, not to scale, of an individual filter and filter cigarette according to one embodiment of the invention
• Fig. 3 is a schematic sectional side elevation view, not to scale, of an individual filter according to a different embodiment of the invention.
• the percentage reductions in mean VP and HCN for cigarettes A to F (each of which includes one of six typical respirator grade activated carbons) as compared to an equivalent cigarette containing no carbon in the filter are given in Table 1.
• the Table also includes the VP and HCN values for a "Standard" cigarette containing a filter which includes an unimpregnated activated carbon derived from coconut shells (as typically used in cigarette filters) .
• respirator samples A to F are not suitable for a cigarette filter environment. It is also clear that the Standard filter is not selective for HCN.
• Samples of impregnated activated carbon were prepared typically by dissolving basic copper (II) carbonate, ammonium carbonate and ammonium dimolybdate (VI) into an aqueous, ammoniacal solution and mixing with the activated carbon according to the ratios detailed in Table 2 (given for 2% copper; 0.5% molybdenum). Quantities for other metal concentrations (and ratios) were adjusted accordingly. The resulting slurry was heat treated to 175°C to give a dry, free flowing product, which was then screened to the required mesh size. Table 2
• HCN retention remains fairly constant when measured as a function of copper and molybdenum concentration (Table 3) . It is therefore surprising that a dramatic reduction of the copper/molybdenum impregnant concentrations, relative to those used in civilian or military respirators, has resulted in no discernible deterioration of the removal of HCN by filters containing these carbons .
• Activated carbons derived from different base materials have been prepared; these show there is little difference in terms of HCN retention between, for example, coal and coconut for the same mesh size, level of impregnation and activity.
• a disadvantage of known carbon containing filters is that the carbon in the filter adsorbs volatile species present in the filter or tobacco during storage, thereby reducing the efficiency with which the carbon can remove VP compounds on smoking. This has the effect that the overall efficiency with which known carbons remove HCN reduces on aging.
• the filters embodying the invention where stored as assembled cigarettes and the change in performance was measured at 0, 3 and 6 months. The results are shown in Table 5.
• FIGs. 1 and 2 respectively are schematic sectional side elevation views, not to scale, of an individual filter and filter cigarette according to one embodiment of the invention.
• the Pig.l filter has a cylindrical buccal end filtering plug 2 of cellulose acetate tow, a cylindrical upstream filtering plug 3 of cellulose acetate tow, and a filter wrapper 4 engaged around the plugs to form a cavity 6 therebetween.
• the cavity 6 is filled with granules 17 of activated carbon impregnated with copper and molybdenum prepared according to the methods above and of identical composition to sample ref 11 described above.
• Fig.2 shows a filter of the Fig.l type joined at its upstream end 7 to a tobacco rod 10 in its own wrap 11 by means of a full tipping overwrap 12 which surrounds and engages the full length of the filter and the adjacent end only of the wrapped tobacco rod 10, 11.
• the filter is 27 mm long and about 25 mm in circumference.
• the buccal end plug 2 is a 10 mm long non-wrapped acetate (NWA) plug - i.e. a preformed non-wrapped plug of plasticised cellulose acetate filaments gathered and bonded together such as is well known in the art .
• NWA non-wrapped acetate
• the upstream end plug 3 is a 10 mm long wrapped acetate (WA) plug - i.e. a preformed wrapped plug of plasticised cellulose acetate filaments.
• the filter wrapper is 27 mm long to give a cavity 6, which is 7 mm long, extending between plugs 2 and 3.
• the cavity 6 is filled with lOOmg of granules 17 of activated carbon impregnated with copper and molybdenum prepared according to the methods above and of identical composition to sample ref 11 described above.
• the filter rod is attached by a ventilating tipping overwrap 12 to a commercial wrapped tobacco rod 10, 11.
• Example 17a the cavity is filled with 100 mg of granules 17 of activated carbon impregnated with copper prepared according to the methods above and of identical composition to Sample Ref. 27 described above.
• Example 17 and Example 17a are similar in construction to a known triple granular filter but include activated carbon according to the invention.
• Fig. 3 is a schematic sectional side elevation view, not to scale, of an individual filter according to a different embodiment of the invention.
• the Fig 3 filter has a cylindrical buccal end filtering plug 52 of cellulose acetate tow and a cylindrical upstream filtering plug 53, also of cellulose acetate tow.
• Particles 67 of activated carbon impregnated with copper and molybdenum prepared according to the methods above and of identical composition to sample ref 11 described above are dispersed throughout the upstream filtering plug 53, carried on the tow or fibres or sheet material which is gathered to form the plug.
• a filter wrapper 54 is engaged around the plugs.
• a filter of the Fig.3 type may be joined at its upstream end 57 to a tobacco rod in the manner shown with reference to Example 17 in Fig 2, for example (e.g. joined to the tobacco rod in its own wrap by means of a full tipping overwrap which surrounds and engages the full length of the filter and the adjacent end only of the wrapped tobacco rod) .
• the filter is 27 mm long and about 25 mm in circumference.
• the buccal end plug 52 is a 14 mm long non-wrapped acetate (NWA) plug - i.e. a preformed non-wrapped plug of plasticised cellulose acetate filaments gathered and bonded together such as is well known in the art.
• NWA non-wrapped acetate
• the upstream end plug 53 is also a 13 mm long preformed plug of plasticised cellulose acetate filaments gathered and bonded together such as is well known in the art. 50mg of particles 67 of activated carbon impregnated with copper and molybdenum prepared according to the methods above and of identical composition to sample ref 11 described above are dispersed throughout filtering plug 53, carried on the tow material (filaments) that was gathered to form the plug. The methods by which the particles may be introduced to the tow material during the gathering process are well known in the art.
• a filter wrapper 54 is engaged around the plugs and is 27 mm long.
• the filter rod may be attached by a ventilating tipping overwrap to a commercial wrapped tobacco rod in the manner shown in Fig 2 and described with reference thereto.
• the cavity is filled with 50 mg of particles 67 of activated cartoon impregnated with copper prepared according to the methods above, and of identical composition to Sample Ref.27 described above, dispersed throughout filter plug 53, carried on the tow material.
• Examples 18 and 18a are similar in construction to a known active acetate filter but include activated carbon according to the invention.
• the filter according to the invention may be of any design previously proposed for particulate adsorbent - containing tobacco smoke filters with the substitution of the known particulate adsorbent with the impregnated activated carbon of the invention.

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• 2003
  • 2003-10-20 GB GBGB0324464.7A patent/GB0324464D0/en not_active Ceased
• 2004
  • 2004-10-19 KR KR1020067007618A patent/KR101155452B1/ko not_active IP Right Cessation
  • 2004-10-19 EP EP04768944.3A patent/EP1679983B1/en active Active
  • 2004-10-19 JP JP2006534834A patent/JP4824568B2/ja active Active
  • 2004-10-19 RU RU2006114447/12A patent/RU2357624C2/ru active
  • 2004-10-19 US US10/576,659 patent/US20070295346A1/en not_active Abandoned
  • 2004-10-19 WO PCT/GB2004/004418 patent/WO2005039333A1/en active Application Filing
  • 2004-10-19 CN CN2004800382301A patent/CN1897833B/zh not_active Expired - Fee Related
  • 2004-10-19 BR BRPI0415618-8B1A patent/BRPI0415618B1/pt not_active IP Right Cessation

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