OA12647A

OA12647A - Cigarette filter.

Info

Publication number: OA12647A
Application number: OA1200400032A
Authority: OA
Inventors: James N Figlar; Brian E Tucker; Charles St F Kelley
Original assignee: Brown & Williamson Tobacco
Priority date: 2001-08-01
Filing date: 2002-07-30
Publication date: 2006-06-16
Also published as: HRP20040166B1; EP1411784B1; KR100838207B1; JP4028483B2; ES2375106T3; CN100496312C; CA2454820A1; NZ531256A; EG23137A; EP1411784B8; BR0211853B1; US20040237984A1; NO20040452L; HUP0401565A2; AP2134A; HRP20040166A2; CA2454820C; AP2004002985A0; US20030066539A1; EP1411784A1

Abstract

A cigarette filter that includes a multiple section filter which reduces the level of predetermined smoke constituents. The filter (130) consists of a fibrous filter plug (132) located at the mouth-end of the cigarette, a section (136) containing a selective adsorbent material, and a section (134) containing a general adsorbent material. The selective adsorbent material, such as a phenol-formaldehyde resin matrix surface-functionalized with mainly primary and secondary amine functional groups, removes specific smoke constituents from the tobacco smoke. The general adsorbent material, such as activated charcoal, is preferably capable of adsorbing a range of chemical compounds without a high degree of specificity. Structurally, the fibrous filter plug, the selective adsorbent section, and the general adsorbent section are co-axially aligned in tandem.

Description

012647 CIGARETTE FILTERby

James N. Figlar, Brian E.Tucker, and Kelley St.Charles

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application daims priority from U.S. Provisional Application Ser. No.60/309,388, filed August 1,2001, which application is incorporated herein byréférencé in its entirety, from U.S. Provisional Application Ser. No. 60/309,435, filed 5 August 1,2001, which application is incorporated herein by référencé in its entiretyand U.S. Patent Application Ser. No. 10/011,841, filed October 30,2001.

BACKGROUND OF THE INVENTION

The présent invention relates to a cigarette filter that includes a smokeconstituent adsorbent which, when combined with a carbon-based filtering material, 10 demonstrates synergistic réductions in smoke vapor constituents.

Cigarettes include tobacco rods or columns which, when bumed, produce aparticulate and a vapor phase. About 70 years ago, filters began to be attached to anend of the tobacco column. Among other things, the filter removed various smokecomponents. Filters made from filamentary or fibrous material, such as cellulose 15 acetate tow or paper, remove the particulate phase of tobacco smoke by mechanicalmeans. However, the fibrous materials are not effective at removing volatileconstituents, such as aldéhydes, hydrogen cyanide and sulfides, which are found in thevapor phase. Typically, an adsorbent or absorbent is combined with the fibrousmaterial to improve removal of the vapor phase components. For example, cigarette 20 filters hâve included activated carbon, porous minerais such as meerschaum, silica 4 012647 gel, cation-exchange resins and anion-exchange resins.

Charcoal has a high spécifie surface area and is a relatively strong adsorbent for vapor-phase constituents of tobacco smoke. When coated with a mixture ofmetallic oxides, charcoal is particularly effective in removing acidic gases. 5 Meerschaum has a large adsorption area with a strong adsorption affinity for chargedspecies, but a considerably low adsorption affinity for non-polar species. Silica gelsare generally regarded as weakly retentive adsorbents for vapor-phase constituents oftobacco smoke. Although silica gel readily adsorbs aldéhydes and hydrogen cyanide,the constituents also readily desorb from the silica gel. Cation exchange resins hâve 10 been proposed for nicotine removal. Anion exchange resins hâve been proposed forthe removal of smoke acids, but strongly basic anion exchangers hâve no effect onsmoke vapor phase aldéhydes. Weakly basic anion-exchange resins of porousstructure are suitable for the removal of smoke acids and aldéhydes, but theirefficiency diminishes during smoking, as does that of carbon and porous minerais. 15 Two or more adsorbents can be used in combination in cigarette filters. For example, U.S. Patent 2,815,760 describes the use of an ion exchange material withmaterials which "chemically react with the harmful, nonalkaline and nonacidcomponents of the smoke to form non-volatile compounds, thus retaining the latter tothe filter." However, the aforesaid additives hâve not yielded satisfactory sélective 20 removal of such smoke phase components, as smoke aldéhydes, particularly acetaldehyde and acrolein. U.S. Patent 4,300,577 describes the use of a weakly retentive absorbent for vapor-phase constituents intermingled with a second component having mainly primary amino functional groups for the removal of vapor- phase constituents, including aldéhydes and hydrogen cyanide from tobacco smoke. 2 012647

However, the filter of the ‘577 patent has not been shown to demonstrate adéquate consumer acceptance or commercial viability.

SUMMARY OF THE INVENTION

The présent invention relates to a cigarette filter that includes a multiplesection filter which reduces the level of predetermined smoke constituents. The filterconsists of a fibrous filter plug located at the mouth-end of the cigarette, a sectioncontaining a sélective adsorbent material, and a section containing a general adsorbent material.

The filter plug can be any filter plug known in the art, such as cellulose acetatetow. The general adsorbent material is preferably selected from a group of relativelyhigh surface area matériels, such as activated charcoal, which are capable of adsorbinga range of Chemical compounds without a high degree of specificity. The sélectiveadsorbent material is chosen based on the spécifie smoke constituents targeted forremoval. Preferably, the sélective adsorbent material is selected from a group ofsurface functionalized resins, wherein each resin consists of an essentially inert carrierwith a surface area of greater than about 35 m2 / g. In an embodiment of the présentinvention, the sélective adsorbent material has a phenol-formaldehyde resin matrixsurface-functionalized with mainly primary and secondary amine functional groups.

Structurally, the sélective adsorbent material may be adjacent to a tobacco rodand the general adsorbent material positioned between the sélective adsorbent sectionand the filter plug. Altematively, the general adsorbent material may be positionedadjacent to the tobacco rod and the sélective adsorbent material between the generaladsorbent section and the filter plug. Preliminary data indicates that the formerorientation produces a synergistic effect in smoke constituent réductions relative to the 3 012647 latter orientation. Further, the sélective adsorbent and general adsorbent may be interspersed in a traditional filter plug material, such as cellulose acetate, or the adsorbents may be packed as a bed or thin layer sections within filter plug material.

BRIEF DESCRIPTION OF THE DRAWINGS 5 Figure 1 is a perspective view of a prior art filter-tipped cigarette;

Figure 2 is a perspective view of a filter for a cigarette made in accordancewith the présent invention wherein the adsorbents are dispersed throughout a filterplug material, and the general adsorbent section is positioned between the filter plugand the sélective adsorbent section; 10 Figure 3 is a perspective view of a filter for a cigarette made in accordance with the présent invention wherein the adsorbents are dispersed throughout a filterplug material, and the sélective adsorbent section is positioned between the filter plugand the general adsorbent section;

Figure 4 is a perspective view of a filter for a cigarette made in accordance 15 with the présent invention wherein the adsorbents are packed as beds within a segmentof a filter plug material;

Figure 5 is a cross-sectional view of an embodiment of the présent inventionwith the filter plug disposed between the general adsorbent section and the sélectiveadsorbent section; 20 Figure 6 is a cross-sectional view of an embodiment of the présent invention with the filter plug adjacent one end of a tobacco rod;

Figure 7 is a cross-sectional view of an embodiment of the présent invention with the adsorbents being sectionalized in a single length of fibrous filter material; and, 4 012647

Figure 8 is a cross-sectional view of an embodiment of the présent inventionabsent a filter plug section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The cigarette filter of the présent invention includes a multiple section filter 5 which reduces the levels of predetermined smoke constituents. The filter consists ofa fibrous filter plug located at the mouth-end of the cigarette, a section containing asélective adsorbent material, and a section containing a general adsorbent material.

As shown in Figure 1 and as is known in the art, a typical filter-tipped cigarette 10 has a filter 30 attached to a tobacco rod 20. The tobacco rod 20 consists of a loose 10 tobacco-containing mixture 22 wrapped in a cigarette paper 24, and the filter 30 includes a filter plug 32 wrapped in a plug wrap 34. A sheet of tipping paper 36 joins the filter 30 to the tobacco rod 20.

In the présent invention, as shown in Figure 2, a cigarette 110 has a multiplesection filter 130 attached to the tobacco rod 20. The filter 130 includes a filter plug 15 132, a section containing a general adsorbent 134 and a section containing a sélective adsorbent 136. The filter plug 132 is adjacent a first or mouth end 131 of the filter130. The bed of the sélective adsorbent 136 is adjacent a second or tobacco-rod end137 of the filter 130. The bed of the general adsorbent 134 is positioned between thefilter plug 132 and the sélective adsorbent bed 136. 20 The filter plug 132 is made from a filamentary or fibrous material and provides a clean, neat appearance at the mouth end 131 of the cigarette. The filter plug 132 also retains a firmness at the mouth end 131 as the cigarette 110 is consumed. As is known in the art, the filter plug 132 can be made from a variety of materials, among the most common being cellulose, cellulose acetate tow, paper, cotton, polypropylene 5 012647. web, polypropylene tow, polyester web, polyester tow or combinations thereof.Optionally, a plasticizer may be included.

The general adsorbent section 134 includes a general adsorbent material 144dispersed throughout a filter plug material 142, such as in a "dual-dalmatian" filter, 5 known in the art. The general adsorbent material 144 is preferably selected from agroup of relatively high surface area materials which are capable of adsorbing smokeconstituents without a high degree of specificity. For example, the general adsorbentcan be selected from activated charcoal, activated coconut carbon, activated coal-based carbon, zeolite, silica gel, meerschaum, aluminum oxide, or combining thereof, 10 as well as a mineral-based charcoal made from semi-anthracite coal with a densityabout 50% greater than coconut-based charcoal (available from Calgon Carbon,Pittsburgh, PA), Ambersorb 572 or Ambersorb 563 (a carbonaceous resin derivedfrom the pyrolysis of sulfonated styrene-divinylbenzene available from Rohm andHaas, 5000 Richmond Street, Philadelphia, PA 19137), other materials having similar 15 particle sizes, surface area and binding affinities, or combinations thereof. To furtherenhance the efficacy of the general adsorbent, métal oxides or other metal-basedcomplexes may be included in the general adsorbent section.

The sélective adsorbent section 136 includes a sélective adsorbent material 146 dispersed throughout a filter plug material 142, such as in a "dual-dalmatian" 20 filter, known in the art. The sélective adsorbent material 146 is preferably selected based on the material's 146 specificity for a predetermined class of Chemical compounds. For example, the sélective adsorbent material 146 may be an ion- exchange resin, such as Duolite A7 (available from Rohm and Haas, 5000 Richmond 6 012647

Street, Philadelphia, PA 19137), or a material having similar functional groups and binding affinities. The Duolite A7 has a phenol-formaldehyde rsin matrix and is surface-functionalized with primary and secondary amino groups, thereby erihancing the resin's specificity toward the aldéhydes and hydrogen cyanide found in tobacco 5 smoke.

Further, the sélective adsorbent material 146 must be selected taking into considération that the contact conditions between the tobacco smoke and the adsorbent 146 are dépendent on a number of variables, including how strongly thesmoker pulls the smoke through the fîlter as the cigarette is being smoked and how 10 much of the tobacco rod has been consumed prior to eachpuff. Thus, itis advantageous that the sélective adsorbent 146 hâve a surface area of greater thanabout 35 m2 / g so that there is minimal diffusional résistance and the surface areafunctional sites are easily accessible. Materials with greater surface areas alsodemonstrate less noticeable performance décliné if part of the surface is covered 15 with a plasticizer, as might occur when the adsorbent 146 is dispersed in the filterplug 142.

When the cigarette is consumed, the tobacco smoke is puffed by the smokerthrough the filter 130. The smoke initially passes over the sélective adsorbentsection 136 where the targeted smoke constituents are adsorbed on the surface of 20 the sélective adsorbent material 146 and particulate matter in the smoke is retained by the filter plug material 142. The remaining smoke then passes over the general adsorbent section 134 where other constituents may be retained by the adsorbent material 144 and additional particulate matter is retained by the filter plug material 7 012641 142. Finally, the remaining smoke then passes tbrough the filter plug 132 whereadditional particulate matter eau be removed. The filtered smoke is then delivered to the smoker.

In a fîrst example embodiment of the présent invention, as shown in Fig. 2, 5 the multiple section filter 110 is made having a filter plug 132 made of celluloseacetate tow and being about 7 mm in length, and having a general adsorbent section134 consisting of 40 mg of activated coconut charcoal 144 dispersed throughoutcellulose acetate tow 142 eut to deliver a section 134 about 10 mm in lengthwherein the cellulose acetate tow is treated with a plasticizer, and having a 10 sélective adsorbent section 136 consisting of 40 mg of Duolite A7 dispersedthroughout cellulose acetate tow 142 eut to deliver a section 136 about 10 mm inlength wherein the cellulose acetate tow is treated with a plasticizer. When thetobacco rod is bumed with a normal puff / rest cycle, analysis of the smoke vaporexiting at the mouth end 131 of the cigarette 110 shows statistically significant 15 réductions in the levels of hydrogen cyanide, furan, propionaldéhyde, acetone,methyl ethyl ketone / butyraldéhyde, hydrogen sulfide, 1,3-butadiene, 2-methylpropanal, isoprene, styrene, pyridine, toluene andbenzene as compared tocigarettes using similar resin-only filters. When the tobacco rod is bumed with anormal puff / rest cycle, analysis of the smoke vapor exiting at the mouth end 131 20 of the cigarette 110 shows statistically significant réductions in the levels of pyridine, hydrogen cyanide, hydrogen sulfide, styrene, 2-methylpropanal, benzene, propionaldéhyde, furan, isoprene, 1,3-butadiene, crotonaldehyde, acetone, acrylonitrile, acetaldehyde, toluene, carbon disulfide, methyl ethyl ketone / 8 012647 butyraldéhyde, propionaldéhyde, acetonitrile, and methanol as compared tocigarettes using charcoal-only filters.

As shown in Figure 2, the multiple section fîlter 130 has the filter plug 132adjacent the mouth end 131, the sélective adsorbent section 136 adjacent thetobacco-rod end 137, and the general adsorbent section 134 positioned between thefilter plug 132 and the sélective adsorbent section 136.

In an alternative embodiment, such as shown in Figure 3, a cigarette 210has a multiple section filter 230 wherein the filter plug 132 is positioned at themouth end 131, the general adsorbent section 134 is adjacent the tobacco-rod end137, and the sélective adsorbent section 136 is sandwiched between the filter plug132 and the general adsorbent section 134. In this embodiment, during a normalpuff, the smoke first passes through the general adsorbent section 134, then throughthe sélective adsorbent section 136, and finally through the filter plug 132.Moreover, the multiple section filter 230 is essentially identical to the filter 130(Fig. 2) of the first example embodiment except that the general adsorbent section134 is adjacent to the tobacco rod 20 and the sélective adsorbent section 136 issandwiched between the filter plug 132 and the general adsorbent section 134.When the tobacco rod is bumed with a normal puff / rest cycle, analysis of thesmoke vapor exiting at the mouth end 131 of the cigarette 210 (Fig. 3) showsstatistically signifîcant réductions in the levels of propionaldéhyde, acetone, methylethyl ketone / butyraldéhyde, crotonaldehyde, hydrogen sulfide, 2-methylpropanal,pyridine, acrolein, toluene, acetaldehyde, acrylonitrile, methanol and benzene ascompared to cigarettes using similar resin-only filters. When the tobacco rod is 9 01264 7. bumed with a normal puff / rest cycle, analysis of the smoke vapor exiting at themouth end 131 of the cigarette 210 shows statistically significant réductions in thelevels of pyridine, hydrogen cyanide, benzene, propionitrile, crotonaldehyde,acetone, acrylonitrile, acetaldehyde, toluene, carbon disulfide, methyl ethyl ketone/ butyraldéhyde, propionaldéhyde, acetonitrile, and methanol as compared tocigarettes using charcoal-only filters.

As shown in another embodiment in Figure 4, in a multiple section filter330 of a cigarette 310, the absorbents 144,146 are packed within the filter plugmaterial as thin layer sections of general absorbent 344 and sélective absorbent346. In this embodiment, the layer packed absorbents are exposed to lessplasticizer than the tow-dispersed absorbents and retain more surface area forinteracting with smoke constituents. Moreover, as shown in Figure 7, a multi-section filter 630 for a cigarette 610 includes the general adsorbent 344 and thesélective adsorbent 346 dispersed in separate sections within a single length of fibrous filter material 342.

An advantage of the embodiment 110 of Figure 2 is that the smoke passesover the sélective adsorbent material 146 before passing over the general adsorbent144. This allows the sélective adsorbent 146 to remove some spécifie smokeconstituents before the general adsorbent 144 is exposed to the smoke, therebyallowing the general adsorbent 144 to be more effective in removing the remainingsmoke constituents. Thus, there is a synergistic effect observed for the adsorbentsin the cellulose acetate / general adsorbent / spécifie adsorbent orientation ascompared to the cellulose acetate / spécifie adsorbent / general adsorbent 10 012647 orientation.

As shown in Figs. 5 and 6, in a multiple section filter 430 and 530 ofcigarettes 410 and 510, respectively, the filter plug 132 is disposed between thegeneral adsorbent section 134 and the sélective adsorbent section 136 in Fig. 5 andis adjacent one end of the tobacco rod 20 in Fig. 6. In Fig. 5 the sélective adsorbentsection 136 is at the mouth end of the filter 430 and in Fig. 6 the general adsorbentsection 134 is at the mouth end of the filter 530. Moreover, as shown in Fig. 8, amultiple section filter 730 of a cigarette 710 includes only a general absorbent section 134 and a sélective absorbent section 136.

The following examples are représentative of the embodiments which canbe prèpared in accordance with the présent invention and the smoke constituentremoval performance of those embodiments. The embodiments presented areintended for example proposes only and are not intended to be limiting in scope.

Example 1 : A cigarette 110 with a multiple section filter 130 is prepared asshown in Figure 2 wherein a filter plug 132 is made of cellulose acetate tow and isabout 7 mm in length, a general adsorbent section 134 consiste of about 40 mg ofactivated coconut charcoal 144 dispersed throughout plasticizer-treated celluloseacetate tow 142 eut to deliver a section 134 about 10 mm in length, and a sélectiveadsorbent section 136 consists of about 40 mg of Duolite A7 dispersed throughoutplasticizer-treated cellulose acetate tow 142 eut to deliver a section 136 about 10mm in length. The filter is attached to a tobacco rod having a length of about 56.5mm and containing about 617 mg of a typical non-menthol cigarette blend wrappedin a 50 Coresta cigarette paper with about 1.8% citrate. The cigarette delivers about 11 012647 10.3 mg tar per cigarette.

Example 2: A cigarette 210 with a multiple section fîlter 230 is preparedwith the section orientations as shown in Figure 3 wherein the fîlter plug 132, thegeneral adsorbent section 134, and the sélective adsorbent section 136 are 5 essentially îdentical to the fîlter plug 132, the general adsorbent section 134, andthe sélective adsorbent section 136 of Example 1. The fîlter is attached to atobacco rod having a length of about 56.5 mm and containing about 617 mg of atypical non-menthol cigarette blend wrapped in a 50 Coresta cigarette paper withabout 1.8% citrate. The cigarette delivers about 10.0 mg tar per cigarette. 10 Example 3: Cigarettes are prepared as in Example 1 except that about 20 mg Duolite A7 is used in the sélective adsorbent section 136 instead of 40 mg. Thecigarette delivers about 10.2 mg tar per cigarette.

Example 4: Cigarettes are prepared as in Example 2 except that about 20mg Duolite A7 is used in the sélective adsorbent section 136 instead of 40 mg. The 15 cigarette delivers about 10.9 mg tar per cigarette.

Example 5: Cigarettes are prepared as in Example 1 except that about 60 mg Duolite A7 is used in the sélective adsorbent section 136 instead of 40 mg. Thecigarette delivers about 10.0 mg tar per cigarette.

Example 6: Cigarettes are prepared as in Example 2 except that about 60 20 mg Duolite A7 is used in the sélective adsorbent section 136 instead of 40 mg. Thecigarette delivers about 10.3 mg tar per cigarette.

Example 7: Cigarettes are prepared as in Example 1 except that about 69 mg of a mineral-based charcoal made from semi-anthracite coal is used in the 12 012647 general adsorbent section 136 instead of 40 mg of activated coconut charcoal. The cigarette delivers about 10.1 mg tar per cigarette.

Example 8: Cigarettes are prepared as in Example 2 except that about 69mg of a mineral-based charcoal made from semi-anthracite coal is used in thegeneral adsorbent section 136 instead of 40 mg of activated coconut charcoal. Thecigarette delivers about 10.2 mg tar per cigarette.

Example 9: Représentative cigarettes of Examples 1 - 6 are smoked to abutt length of about 4 mm from the tipping using a Borgwalt RM-20 smokingmachine. Following the procedures set forth by the ETC, smoke constituentsexiting the filter end of each cigarette are passed through a Cambridge filter pad,the vapor phase is collected in a bag and analyzed by GC/MS. The data isnormalized to about 10 mg tar per cigarette.

Average Vapor Phase Yields ^g/cig)

Cigarettes Prepared byExample: 1 2 3 4 5 6 mg 40 20 60 Duolite/cigarett e Filter Segment CA/GA CA/SA/ CA/GA/ CA/SA/ CA/GA/ CA/SA/ Order /SA GA SA GA SA GA Âcetaldehyde 330.9 333.7 380.7 346.2 320.3 310.9 Isoprene 231.4 240.4 252.1 246.1 227.4 227.2 Aeetone 144.1 163.5 156.0 160.5 148.0 151.4 Methanol 104.9 127.6 114.5 142.8 111.7 98.5 Acetonitrile 59.8 72.0 67.0 77.4 62.8 57.3 Acrolein 29.6 31.4 33.6 32.2 28.5 29.9 Methyl ethyl 29.3 35.9 30.9 38.5 30.1 31.6 ketone Formaldéhyde 23.5 25.8 25.5 25.0 22.1 24.5 Propionaldehyd 25.7 27.4 29.3 28.5 25.3 25.0 1,3-Butadiene 25.5 25.9 27.5 25.5 25.8 25.0 Toluene 22.5 25.3 22.0 27.5 23.9 22.5 Benzene 20.6 23.6 21.6 24.1 21.1 21.4 13 012647

Acrylonitrîle 16.8 17.7 18.0 18.0 17.0 16.5 Furan 16.2 17.0 17.3 16.4 16.4 16.2 Hydrogen 15.1 16.4 20.7 19.6 13.6 14.8 cyanide Hydrogen 12.9 13.0 14.0 12.9 13.1 12.7 sulfide Propionitrile 12.9 15.0 13.5 15.9 13.6 12.8 2- 6.4 6.7 7.0 7.0 6.6 6.4 Methylpropana 1 Crotonaldehyd 5.1 5.9 5.5 6.3 5.3 5.0 Carbon 2.5 2.6 2.7 2.6 2.6 2.5 disulfide Styrene 2.0 1.8 2.2 1.9 2.1 1.7 Pyridine 1.9 1.9 1.9 1.8 1.9 1.8 CA=cellulose acetale filter plug; GA = general adsorbent section; SA sélective adsorbent section

Example 10: Représentative cigarettes of Exemples 7 and 8 are smokedtoa butt length of about 4 mm from the tipping using a Borgwalt RM-20 smoking 20 machine. Following the procedures set forth by the FTC, smoke constituentsexiting the filter end of each cigarette are passed through a Cambridge filter pad,the vapor phase is collected in a bag and analyzed by GC/MS. The data isnormalized to about 10 mg tar per cigarette.

Average Vapor Phase Yields (pg/cig) 25 Cigarettes Preparedby Example: 7 8 mg Duolite/cigarette 40 Filter Segment Order CA/GA/S CA/SA/ A GA Acetaldehyde 343.4 364.2 30 Isoprene 225.0 268.9 Acetone 138.6 162.3 Methanol 95.1 134.7 Acetonitrile 61.4 84.6 Acrolein 9.8 35.3 35 Methyl ethyl ketone 28.3 39.8 Propionaldéhyde 26.4 30.2 1,3-Butadiene 25.4 27.7 Toluene 18.7 24.2 Benzene 21.3 27.3 40 Acrylonitrile 7.5 9.0 14 012647 iFuran 17.0 18.4 Hydrogen cyanide 16.7 19.5 Hydrogen sulfide 14.7 14.1 Propionitrile 15.7 20.3 2-Methylpropanal 13.0 14.8 Crotonaldehyde 3.3 5.1 Carbon disulfide 2.8 2.8 Styrene 1.8 2.1 Pyridine 1.3 1.4 CA = cellulose acetate filter plug; GA = general adsorbent section; SA = sélective adsoibent section

From a production perspective, there are some advantages to dispersing thesélective adsorbent material 146 and the general adsorbent material 144 throughoutthe filter tow 142. Specifically, when the adsorbents 144,146 are dispersed withinthe tow 142, the adsorbents are easier to handle than they are as loose particles.However, when the adsorbents 144,146 are dispersed within the tow 142, there is arisk that any plasticizer which is used on the tow 142 will affect the surface of theadsorbents 144,146, thereby reducing the adsoiption capacity. Thus, as shown inFigure 4, the adsorbents 144,146 may be packed within the filter plug material 142as thin layer sections of general adsorbent 344 and sélective adsorbent 346.

Because the layer packed adsorbents would not be exposed to the same level ofplasticizer as the tow-dispersed adsorbents, the adsorbents would retain moreavailable surface area for interacting with smoke constituents.

From a reading of the above, one with ordinary skill in the art should beable to devise variations to the inventive features. For example, the filter plug, thegeneral adsorbent section, and the sélective adsorbent section may vary in lengthand diameter, relative to any dimensions specified herein and relative to each other.Further, the various section dimensions may be optimized for a particular tobaccoblend or for particular tobacco rod dimensions. These and other variations are 15 012647 believed to fall within the spirit and scope of the attached daims. 16

Claims

012647 CLA1MS

1. A multiple section cigarette fîlter comprising: (a) a sélective adsorbent section comprising a sélectiveadsorbent material having an affmity for a predetermined class of Chemical5 compounds dispersed throughout a fibrous material; and (b) a general adsorbent section comprising a general adsorbentmaterial having a high surface area and being capable of adsorbingsmoke constituents without a high degree of specificity, saîdsélective adsorbent section, and said general adsorbent section beingaxially aligned in tandem,
2. The cigarette fîlter of daim 1 wherein said sélective adsorbentmaterial is an ion-exchange resin.
3. The cigarette fîlter of Claim 2 wherein said sélective adsorbentmaterial has a surface area sofficient to ensure that the surface fimctîonal 4Î> sites are easily accessible to a smoke constituent
4. The cigarette fîlter of daim 2 wherein said ion-exchange resin has aphenol-fonnaldehyde resin matrix and is surface-functionalized withprimaxy and secondary amine groups.
5. The cigarette fîlter of Claim 2 wherein said sélective adsorbent -2-θ * section comprises said sélective adsorbent material dispersed throughout a fibrous material.
6. The cigarette fîlter of Claim 2 wherein said sélective adsorbentsection comprises a close-packed hed of said sélective adsorbent material 17 012647
7. The cigarette filter of claim 1 wherein said general adsorbent matérielis selected from the group consisting of activated charcoal, activatedcoconut carbon, activated coal-based carbon, zeolite, silica gel, meerschaum, aluminum oxide, a coal-based charcoal made from semi- anthracite çoal, a carbonaceous resin derived from the pyrolysis ofsulfonated styrene-divinylbenzene, or combinations thereof.
8. The cigarette filter of claim 7 wherein said general adsorbent sectioncomprises said general adsorbent material dispersed throughout a fibrous material.
9. The cigarette filter of claim 7 wherein said general adsorbent sectioncomprises a close-packed bed of said general adsorbent material.
10. The cigarette filter of claim 7 wherein said general adsorbent sectionfurther includes a métal oxide or other metal-based complex.
11. The cigarette filter of claim 1 including a fibrous filter plug whereinsaid filter plug is made from cellulose, cellulose acetate tow, paper, cotton,polypropylene web, polypropylene tow, polyester web, polyester tow or acombination thereof, said fibrous filter plug being co-axially aligned intandem with said sélective adsorbent section and said general adsorbent section.
12. The cigarette filter of claim 11 wherein said filter plug furtherincludes a plasticizer, a liquid additive, a flavoring agent or a combination thereof.
13. The cigarette filter of claim 11 wherein said general adsorbent section 18 01 is positioned between said fibrous fîlter plug and said sélective adsorbent section.
14. The cigarette fîlter of claim 11 wherein said sélective adsorbentsection is positioned between said fibrous fîlter plug and said general adsorbent section.
15. The cigarette fîlter of Claim 11, said fibrous fîlter plug beingpositioned between said sélective adsorbent section and said general adsorbent section.
16. The cigarette fîlter of Claim 1, including a plug wrap circumscribingsaid general adsorbent section and said sélective adsorbent section.
17. The cigarette fîlter of claim 1, said sélective absorbent material havingsurface area greater than about 35 m2/g.
18. A multiple section cigarette fîlter comprising: (a) a fibrous fîlter plug selected from the group consisting ofcellulose, cellulose acetate tow, paper, cotton, polypropylene web,polypropylene tow, polyester web, polyester tow or a combinationthereof; (b) a sélective adsorbent section comprising an ion-exchangeresin having a surface area sufficient to ensure that the surfacefunctional sites are easily accessible to a smoke constituent; and (c) a general adsorbent section comprising a general adsorbentmaterial selected from the group consisting of activated charcoal,activated coconut carbon, activated coal-based carbon, zeolite, silica 19 012647 AO 2o gel, meerschaum, aluminum oxide, a coal-based chaicoal made from semi-anthracite coal, a carbonaceous resin derived from the pyrolysis of sulfonated styrene-divinylbenzene, or combinations thereof, saîd fîbrous fil ter ping, saîd sélective adsorbent section, and said general adsorbent section being axially aligned in tandem.
19. The cigarette filtsr of claim 18 wherein said ion-exchange resin hasa phenol-formaldehyde resin matrix and is surface-functionalized withprimary and secondary amine groupe.
20. The cigarette filter ofclaùn 18 wherein said sélective adsorbentsection comprises said ion-exchange resin dispersed throughout a fîbrousmaterial.
21. The cigarette filter of daim 18 wherein said sélective adsorbentsection comprises a close-packed bed of said ion-exchange resin.
22. The cigarette filter of claim 18 wherein said general adsorbentsection comprises said general adsorbent material dispersed throughout afîbrous material.
23. The cigarette filter of claim 22 wherein said general adsorbentsection firrther includes an additive selected from a métal oxide or othermetal-based complex.
24. The cigarette filter of claim 18 wherein said general adsorbentsection comprises a close-packed bed of said general adsorbent material.
25. The cigarette filter of claim 24 wherein said general adsorbent 20 012647 section further includes an additive selected fiom a métal oxide or ametal- based complex.
26. The cigarette filter of claim 18 wherein said fîlter plug is made from cellulose acetate tow.
27. The cigarette filter of claim 18 wherein said filter plug further includes a plasticizer, a liquid additive, a flavoring agent or a combination thereof.
28. The cigarette filter of claim 18 wherein said general adsorbentsection is positioned between said fibrous filter plug and said sélective 10 adsorbent section,
29. The cigarette filter of claim 18 wherein said sélective adsorbentsection is positioned between said fibrous filter plug and said general adsorbent section.
30. The cigarette filter of claim 18, said fibrous filter plug being 15 positioned between said sélection absorbent section and said general absorbent section.
31. The cigarette filter of claim 18, said sélective absorbent material 20 having a surface area greater than 35 m2/g. 21