Abstract:
A wrapper for a smoking article which, when wrapped about a tobacco column, provides improved sidestream smoke reduction, improved ash formation, and improved mainstream smoke taste and sidestream smoke odor subjectives. These objectives are attained by forming a single cellulosic sheet containing a filler combination of magnesium hydroxide activated carbon, and calcium carbonate. In addition, the sheet may be treated with a burning chemical such as potassium citrate, an organic acid such as citric acid, and a sugar such as sucrose. Considerable latitude exists in regard to sheet basis weight, filler levels, sheet porosity, burn rate and size press solution treatment in order to optimize product requirements.

Description:
SUMMARY OF THE INVENTION 
     This invention relates to a smoking article wrapper which, when provided with a suitable tobacco column, produces less particulate sidestream smoke than do cigarettes fabricated with conventional cigarette paper wrappers, produces a well formed ash which clings tightly without premature flaking and burns at an acceptable rate, and to methods of producing same. 
     BACKGROUND OF THE INVENTION 
     The reduced sidestream smoke cigarette paper patents which describe magnesium oxide/hydroxide as paper fillers, which are assigned to Olin Corporation, Ecusta Corporation or P. H. Glatfelter Company, and which disclose burning chemical types and levels are U.S. Pat. Nos. 4,231,377; 4,450,847; 4,881,557; and 4,915,118. These patents claim alkali metal acetates, citrates, nitrates, carbonates and tartrates as burning chemical types at levels in the sheet ranging from 0.5% to 8.0%. 
     The Kimberly-Clark Corporation and Cookson Group, plc patents dealing with reduced sidestream smoke cigarette paper are U.S. Pat. Nos. 4,461,311 and 4,804,644. These patents disclose the use of sodium and potassium salts of carbonic, formic, acetic, propionic, malic, lactic, glycolic, citric, tartaric, fumaric, oxalic, malonic, nitric, and phosphoric acids at levels in the sheet up to 16% by weight (levels up to 25% are also disclosed) and high superficial surface area, thermally stable fillers. 
     U.S. Pat. No. 3,744,496, assigned to Olin Corporation, discloses a carbon-filled paper to wrap cigarettes and/or cigars, preferably used as an inner liner, with regular cigarette paper or cigar wrapper as an outer wrap. 
     OBJECTS OF THE INVENTION 
     The purpose of this invention is to provide a cigarette paper or cigar wrapper which, when fabricated into a cigarette or cigar with a suitable tobacco column, statically burns at an acceptable rate, produces a light-colored, well formed ash which clings tightly without premature flaking, delivers both mainstream and sidestream smoke with a subjectively pleasant taste and aroma, and has significantly reduced sidestream smoke. More specifically, these desirable properties are achieved by a mixture of magnesium hydroxide, activated carbon and calcium carbonate to produce a base cigarette paper or cigar wrapper, and this paper is subjected to treatments as described in U.S. patent application Ser. No. 514,333, filed Apr. 26, 1990, (acid treatment) and Ser. No. 514,885, filed Apr. 26, 1990, (sugar addition). Further sidestream aroma and mainstream taste improvements may be effected by absorption onto all or part of the activated carbon such flavorants as menthol, vanillin, ethyl vanillin, propenyl guaethol, and glycyrrhiza which are released by the heat of the burning zone to enter the sidestream and mainstream smoke. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It has been found that by putting activated carbon in the furnish of the paper, along with magnesium hydroxide and calcium carbonate, and incorporating the teachings of U.S. patent applications Ser. No. 514,533 (acid treatment) and Ser. No. 514,885 (sugar addition), an enhancement in sidestream smoke reduction is obtained over magnesium hydroxide/calcium carbonate only, while obtaining a significant improvement in ash properties and mainstream taste subjectives. The resulting cigarette is distinctly light to dark gray in color, depending on the particle size and level of carbon in the paper. The truly novel findings in this work are the improvements in sidestream smoke reduction, ash, and subjective taste properties of cigarettes wrapped in papers containing a mixture of magnesium hydroxide, activated carbon and calcium carbonate over the same papers with only magnesium hydroxide and calcium carbonate or activated carbon and calcium carbonate fillers. 
     
         ______________________________________PARAMETERS OF THE INVENTION______________________________________Carbon content:   2.0 to 40%Preferred         5.0 to 25%Magnesium Hydroxide content:             2.0% to 35%Preferred         5.0% to 20%Calcium Carbonate content:             5.0% to 40%Preferred         10% to 30%Basis Weight:     25 gm/m.sup.2 to 100 gm/m.sup.2Preferred         35 gm/m.sup.2 to 65 gm/m.sup.2Porosity:         1 to 25 CorestaPreferred         5 to 12 CorestaBurning Chemical: Alkali metal salts of             organic or inorganic acids             selected from the group             consisting of citric, malic,             lactic, glycolic, tartaric,             fumaric, maleic, malonic,             glutaric, adipic, acetic,             succinic, hydrochloric and             phosphoric.Burning Chemical Addition Rate:             0.5% to 6.0%Acid Addition Rate:             1.0% to 10% acid compatible             with the alkali metal salt             burning chemical.Sugar Addition Rate:             1.0% to 10% mono-, di-, tri-             or poly-saccharides.Flavorant:        Adsorbed onto the carbon.Smoking Articles: Cigarettes, cigars, and the             like.______________________________________ 
    
     The size of the particles of the incorporated activated carbon is significant in that the smaller the particles, the darker the finished paper sheet, and if the particles are too large, they cause &#34;sparking&#34; which would not be tolerable in a commercial smoking article. 
     The preferred particle size (by ASTM method E-11) measured on an air-jet sieve would be 98+% through 325 mesh. Questionable particle size would be larger than 8.4% on 200 mesh, 25.6% on 325 mesh, and 65.1% through 325 mesh. 
     
                       TABLE I______________________________________TASTE SUBJECTIVES______________________________________Cigarette Base Paper        10% Magnesium Hydroxide        10% Activated Carbon (North American        Carbon Co.) (98.6%, 325 mesh)        GX248        20% Calcium Carbonate        Porosity = 9 Coresta        Basis Weight = 45 gm/m.sup.2Test Cigarettes - Commercial 100 mm &#34;Lights&#34; brand withstandard paper removed and replaced with the experimentalreduced-sidestream-smoke cigarette papers.______________________________________                          SubjectiveAdditive/Burning Chemical            Odor/Taste Results                          Preference______________________________________1)   5.6% Potassium Citrate                Cigar type aroma                              5                Harsh         (worst)                After Taste2)   5.6% Potassium Citrate                Normal Aroma  3   +            Less Harsh2.3% Citric Acid                Less After Taste3)   5.6% Potassium Citrate                Cigar Aroma   4   +            Less Harsh6.0% Sucrose    Less After Taste4)   5.6% Potassium Citrate                Normal Aroma  l   +            Smooth        (best)2.3% Citric Acid                No After Taste   +4.5% Sucrose5)   5.6% Potassium Citrate                Normal Aroma  2   +            Peppery2.3% Citric Acid                No After Taste    +6.0 Sucrose______________________________________ 
    
     It is observed from the above study that the addition of both citric acid and sucrose to the base paper containing magnesium hydroxide, activated carbon, and calcium carbonate gives improvements in sidestream aroma and mainstream taste, and when the two are combined, the best products are produced in terms of subjective taste and aroma properties. 
     
                                           TABLE II__________________________________________________________________________SIDESTREAM REDUCTIONTest Cigarettes - Commercial 100 mm &#34;Lights&#34; brand with standard paperremoved and replaced with theexperimental reduced-sidestream-smoke cigarette papers.          Basis weight                 %   %    %   CorestaCigarette Paper          gm/m.sup.2                 CaCO.sub.3                     Mg(OH).sub.2                          Carbon                              Porosity                                   SBR.sup.1                                       SSGR.sup.2                                           TSS.sup.3__________________________________________________________________________Control - Ecusta 12556          25     30   0    0  25   56.7                                       2.13                                           28.3Heavyweight + 1% K.sub.3 Citrate          45     20   0    0  9    50.7                                       1.46                                           20.2LSS - Mg(OH).sub.2.sup.4          45     30  10    0  9    56.7                                       0.99                                           13.2LSS - Mg(OH).sub.2 /Carbon.sup.4          45     25  10    5  9    55.8                                       0.91                                           13.0LSS - Mg(OH).sub.2 /Carbon.sup.4          45     20  10   10  9    50.9                                       0.79                                           12.1LSS - Mg(OH).sub.2 /Carbon.sup.4          45     15  10   15  9    45.6                                       0.71                                           11.2LSS - Mg(OH).sub.2 /Carbon.sup.4          45     10  10   20  9    41.4                                       0.62                                           11.6LSS - Mg(OH).sub.2 /Carbon.sup.4          45     20  10   10  18   61.7                                       0.99                                           12.4LSS - Mg(OH).sub.2 /Carbon.sup.4          45     15  10   15  13   59.3                                       0.80                                           10.4LSS - Mg(OH).sub.2 /Carbon.sup.4          35     20  10   10  9    43.3                                       0.78                                           14.1LSS - Mg(OH).sub.2 /Carbon.sup.4          55     20  10   10  9    53.7                                       0.74                                           11.2LSS - Carbon.sup.4          45     30   0   10  18   65.2                                       1.03                                           12.6__________________________________________________________________________ .sup.1 SBR = Static Burn Rate  mg/min .sup.2 SSGR = Sidestream Generation Rate  mg/min .sup.3 TSS = Total Sidestream  mg/cigarette .sup.4 Burning Chemical Content = 5.6% potassium citrate, 2.3% citric acid, 6% sucrose 
    
     COMMENTS - TABLE II 
     In reviewing Table II results, it will be observed that the combination of magnesium hydroxide/carbon/calcium carbonate-filled papers are giving the greatest sidestream smoke reductions, as judged by the sidestream smoke generation rate (SSGR)--being greater as the level of carbon in the paper is increased. Previous studies have shown the sidestream reduction also increases with the increase in the level of magnesium hydroxide, but the overall subjective ash properties decline with increases in the magnesium hydroxide level. The total sidestream tar (TSS) is greatly influenced by the burn rate of the cigarette and is higher the slower the static burn rate. Burn rate control can be effected by burning chemical type and level, basis weight, sheet porosity, filler type and level, and the type and level of magnesium hydroxide in the paper. 
     
                       TABLE III______________________________________ASH PROPERTIESTest Cigarettes - Commercial 100 mm &#34;Lights&#34; brand withstandard paper removed and replaced with the experimentalreduced-sidestream-smoke cigarette papers.Cigarette Paper      Static Ash     Puffed Ash______________________________________Control.sup.1      Tight shrinkage                     Tight shrinkage      Light gray     Light gray      No flake fall-off                     No flake fall-off      Solid sheath   Small adhering flakesMg(OH).sub.2 - 35%.sup.2      Outward flare  No shrinkage      Light gray     Light gray      Total ash fall-off                     Moderate flake fall-off      Cracked sheath Cracked sheathMg(OH).sub.2 - 10%.sup.3      No shrinkage   Tight shrinkage      Light gray     Light gray      Minimal flake fall-off                     No flake fall-off      Cracked sheath Cracked sheathMg(OH).sub.2 - 10%.sup.4      Tight shrinkage                     Tight shrinkageCarbon - 10%      Light gray     Light gray      No flake fall-off                     No flake fall-off      Solid sheath   Small adhering flakes______________________________________ .sup.1 Ecusta 12556 Cigarette Paper: 30% Calcium Carbonate, 25 Coresta Porosity, 25 gm/m.sup.2, 0.55% Citrate burning chemicals. .sup.2 35% Magnesium hydroxide, 5% Calcium Carbonatefilled 45 gm/m.sup.2 paper treated to contain 5.6% potassium citrate, 2.3% citric acid, and 6.0% sucrose, 10 Coresta porosity. .sup.3 10% magnesium hydroxide, 30% calcium carbonatefilled 45 gm/m.sup.2 paper treated to contain 5.6% potassium citrate, 2.3% citric acid, and 6.0% sucrose, 9 Coresta porosity. .sup.4 10% magnesium hydroxide, 10% activated carbon, 20% calcium carbonatefilled 45 gm/m.sup.2 paper treated to contain 5.6% potassium citrate, 2.3% citric acid, and 6.0% sucrose, 9 Coresta porosity. 
    
     COMMENTS - TABLE III 
     It will be observed in reviewing Table III results, the combination of magnesium hydroxide/carbon/calcium carbonate-filled paper is giving ash properties very similar to that obtained with regular (control) cigarette paper with no significant differences being observed between these two papers. 
     
                                           TABLE IV__________________________________________________________________________ADSORBED FLAVORANTTest Cigarettes - Commercial 100 mm &#34;Lights&#34; brand with standard paperremoved and replaced with the experimental reduced-sidestream-smokecigarette papers.     Sidestream Reduction                     Taste/AromaCigarette Paper     Porosity          SBR.sup.1              SSGR.sup.2                  TSS.sup.3                     Taste    Aroma__________________________________________________________________________Vanillin.sup.4     9    48.2              0.78                  12.2                     Very low vanillin                              Mild vanillinEthyl Vanillin 10%.sup.5     9    47.4              0.77                  12.3                     Low vanillin                              Strong vanillinPropenyl Guaethol.sup.6     8    43.1              0.64                  11.5                     Low sweet                              SweetEthyl Vanillin 5%.sup.7     9    46.9              0.74                  12.3                     Very low vanillin                              Mild Vanillin__________________________________________________________________________ .sup.1 Static Burn rate  mg/min. .sup.2 SBR = Sidestream Generation Rate  mg/min. .sup.3 TSS = Total Sidestream Tar  mg/cigarette .sup.4 Activated Carbon/Vanillin Preparation - Dissolve 1.0 gm. Vanillin in 2.0 gm. 95% Ethyl Alcohol solution and add with constant stirring to 10.0 gms. of GX203 Activated Carbon from North American Carbon, Inc.. Let stand in closed container overnight before using to prepare handsheets. .sup.5 Activated Carbon/Ethyl Vanillin  10% Preparation. Same as footnote 4, except Ethyl Vanillin is used in place of Vanillin. .sup.6 Activated Carbon/Propenyl Guaethol Preparation. Same as footnote 4 except Propenyl Guaethol is used in place of Vanillin. .sup.7 Activated Carbon/Ethyl Vanillin  5% Preparation. Same as footnote 4, except only 0.5 gms. of Ethyl Vanillin is used in place of the Vanillin.