Activated carbon for smoking articles

Abstract

A smoking article includes a smokable material and a filter downstream of the smokable material. The filter includes activated carbon material having a BET of between 1000 and 2000 m.sup.2/g and exhibiting less particle breakthrough than granulated coconut shell derived activated carbon currently used for filters of smoking articles.

Claims

1. A method comprising: physically activating a composition comprising cellulosic material and an added activatable binder to form an activated carbon material; providing filter material for use in a smoking article; and combining the activated carbon material and the filter material to form a filter for a smoking article.

2. A method according to claim 1, further comprising incorporating the formed filter into a smoking article.

3. A method according to claim 1, wherein the activated carbon material is extruded activated carbon material.

4. A method according to claim 1, wherein the activatable binder comprises a lignin compound.

5. A method according to claim 4, wherein the cellulosic material comprises one or more of wood and olive stone.

6. A method comprising: forming a filter of a smoking article by incorporating activated carbon material formed from a physical activation process that includes carbonizing a composition comprising cellulosic material and an added activatable binder.

7. A method according to claim 6, wherein the activated carbon material is extruded activated carbon material.

8. A method according to claim 6, wherein the activatable binder comprises a lignin compound.

9. A method according to claim 6, wherein the cellulosic material comprises one or more of wood and olive stone.

10. A smoking article comprising: a smokable material; and a filter comprising activated carbon material downstream of the smokable material, the activated carbon material having a BET of between 1000 and 2000 m.sup.2/g and a ball-pan hardness of greater than about 95%; wherein the activated carbon material is formed from a physical activation process that includes carbonizing a composition comprising cellulosic material and an added activatable binder; and wherein the activated carbon material exhibits, in a standard plug-space-plug configuration test filter, less particle breakthrough than granulated coconut shell activated carbon activated to the same degree.

11. A smoking article according to claim 10, wherein the activated carbon material has a BET from about 1200 m.sup.2/g to about 1800 m.sup.2/g.

12. A smoking article according to claim 10, wherein the activated carbon material exhibits about 10% or more reduction in particle breakthrough than the granulated coconut shell activated carbon activated to the same degree.

13. A smoking article according to claim 10, wherein no coating or residue is disposed on the activated carbon material.

14. A smoking article according to claim 10, wherein the activated carbon material is extruded activated carbon material.

Description

(1) FIG. 1 is a schematic perspective views of an embodiment of a partially unrolled smoking article.

(2) FIG. 2 is a schematic perspective views of an embodiment of a partially unrolled smoking article.

(3) FIG. 3 is an example of representative images of activated carbon granules or cylinders.

(4) FIG. 4 illustrates example results of particle breakthrough experimentation associated with carbon on tow configurations.

(5) FIG. 5 illustrates example results of particle breakthrough experimentation associated with plug-space-plug configurations.

(6) FIG. 6 is an example diagram illustrating an ability of GCN REF and WOOD activated carbon filters to adsorb various smoke constituents in a plug-space-plug configuration.

(7) FIG. 7 is an example diagram illustrating an ability of GCN REF and WOOD EXTRUDED activated carbon filters to adsorb various smoke constituents in a carbon on tow configuration.

(8) FIGS. 1-2 are schematic perspective views of embodiments of partially unrolled smoking articles. The smoking articles depicted in FIGS. 1-2 illustrate embodiments of smoking articles or components of smoking articles described above. The schematic drawings are not necessarily to scale and are presented for purposes of illustration and not limitation. The drawings depict one or more aspects described in this disclosure. However, it will be understood that other aspects not depicted in the drawings fall within the scope and spirit of this disclosure.

(9) Referring now to FIG. 1, a smoking article 10, in this case a cigarette, is depicted. The smoking article 10 includes a rod 20, such as a tobacco rod, and a mouth end filter 30. The filter 30 includes a mouth end segment 32, such as a white cellulose acetate tow segment, and an upstream carbon on tow segment 34. Filter segments 32 and 34 are shown as being separated for purposes of illustration, but may be abutting. Similarly, filter segment 34 and rod 20 are shown as being separated for purposes of illustration, but may be abutting. The depicted smoking article 10 includes plug wrap 60, cigarette paper 40, and tipping paper 50. In the depicted embodiment, the plug wrap 60 circumscribes at least a portion of the filter 30. The cigarette paper 40 circumscribes at least a portion of the rod 20. Tipping paper 50 or other suitable wrapper circumscribes the plug wrap 60 and a portion of the cigarette paper 40 as is generally known in the art.

(10) FIG. 2 illustrates an embodiment where filter 30 is in a plug 32-space 37-plug 35 configuration. Activated carbon (not shown) may occupy the void space 37 between filter plugs 32 and 35. In FIG. 2, filter segment 35 and rod 20 are shown as being separated for purposes of illustration, but may be abutting. In FIG. 2 components labelled with the same number as components depicted in FIG. 1 are the same as, or similar to, those components as discussed with regard to FIG. 1 above. For those components not specifically discussed with regard to FIG. 2, reference is made to the discussion above with regard to FIG. 1.

(11) Non-limiting examples illustrating activated carbon as described above and filters and smoking articles having such activated carbon are described below.

EXAMPLES

(12) In the following examples, characterization of activated carbon produced from a variety of sources and the function of some of the activated carbon in filters of smoking articles is described.

(13) The characterized activated carbon includes coconut shell-derived activated carbon activated to a BET of 1100 m.sup.2/g (GCN REF), coconut shell-derived activated carbon activated to a BET of 1400 m.sup.2/g (GCN EXTRA), wood (pine) derived activated carbon activated to a BET of 1200 m.sup.2/g (WOOD), olive stone derived activated carbon activated to a BET of 1600 m.sup.2/g (OLIVE STONE), and extruded wood (wood=activatable binder) derived activated carbon activated to a BET of 1500 m.sup.2/g (WOOD EXTRUDED).

(14) GCN REF activated carbon was obtained from Cabot-Norit by steam activation. GCN EXTRA activated carbon was obtained from Cabot-Norit by steam activation. WOOD activated carbon was obtained from Cabot-Norit by steam activation. OLIVE STONE activated carbon was obtained from Cabot-Norit by chemical activation. WOOD EXTRUDED activated carbon was obtained from Cabot-Norit by steam activation after extrusion process.

(15) Density, BET, mesh size or diameter, and ball-pan hardness for each of the activated carbon materials was tested or obtained from manufacturer specifications. Density was determined as follows. Briefly, density was determined according to ASTM D2854-09. BET was determined from using N.sub.2 adsorption isotherm at ?196? C. obtained in a volumetric Autosorb-6B apparatus from Quantachrome generally as described in the following (i) Gregg S J, Sing K S W. Adsorption, Surface Science and Porosity. Academic Press, New York 1982; and (ii) Rouquerol F, Rouquerol J, Sing K. Adsorption by powders and porous solids. Principles, methodology and applications. Academic Press, 1999; (iii) Linares-Solano A, Salinas-Martinez de Lecea C, Alca?iz-Monge J, Cazorla-Amor?s D. Further advances in the characterization of Microporous carbons by Physical adsorption of gases. Tanso 1998; 185:316-25.

(16) Ball-pan hardness was determined according to ASTM D3802-10.

(17) The results of characterization of the activated carbon are presented in Table 1 below.

(18) TABLE-US-00001 TABLE 1 Characterization of Activated Carbon Ball-pan Activated Density BET Mesh size Hardness Carbon (g/cm.sup.3) (m.sup.2/g) (US) (%) Type GCN REF 0.49 1100 30 ? 70 98 Granules GCN EXTRA 0.39 1400 30 ? 70 98 Granules WOOD 0.35 1200 30 ? 70 98 Granules WOOD 0.42 1500 0.8 mm 99 Cylinder EXTRUDED diameter, length 2-4 mm OLIVE STONE 0.32 1600 30 ? 70 75 Granules

(19) Representative images of activated carbon granules or cylinders used are shown in FIG. 3. As shown in FIG. 3, the relative amounts of dusting observed were as follows: OLIVE STONE?GCN EXTRA>WOOD>GCN REF>>WOOD EXTRUDED.

(20) Particle breakthrough and smoke constituent adsorption experiments were performed on filters of cigarettes, where the filters contained activated carbon. Activated carbon was incorporated into a void space of a filter in a plug-space-plug configuration or incorporated into a filter in a carbon on tow configuration. For the carbon on tow configuration, the filter contained a 7 mm mouth end section of white cellulose acetate tow abutted by a 20 mm cellulose acetate tow section into which 60 mg of activated carbon was incorporated. For the plug-space-plug configuration, the filter contained a 11 mm mouth end section of cellulose acetate tow and a 11 mm rod end section of cellulose acetate tow. The mouth end section and the rod end section were separated by a gap of 5 mm into the void space of which 110 mg of activated carbon was placed.

(21) The filters containing activated carbon were incorporated into prototype cigarettes having a 57 mm long tobacco rod containing tobacco at about 700 mg. A control cigarette having a 27 mm cellulose acetate tow filter was also tested.

(22) For particle breakthrough testing, the cigarettes were operably coupled to a smoking machine operably coupled to an AEROTRAK laser light scattering particle counter configured to detect particles in the size range of 0.3 micrometers to 10 micrometers. The cigarettes were dry puffed (unlit) by the machine for 12 puffs of 55 mL during 2 seconds every 13 seconds. Results were averaged for ten cigarettes for each tested filter construction.

(23) For smoke constituent yields analysis, the cigarettes were tested according to (Coresta Methods) CRM N070 Determination of Selected Volatile Organic Compounds in the Mainstream Smoke of Cigarettes-Gas Chromatography-Mass Spectrometry Method and CRM No 74 Determination of Selected Carbonyls in Mainstream Cigarette Smoke by High Performance Liquid Chromatography (HPLC). Yields of acetaldehyde, acroleine, formaldehyde, benzene, and butadiene were evaluated.

(24) Results of the particle breakthrough experimentation are shown in FIGS. 4-5. In FIG. 4 results for carbon on tow configurations are shown. Particle counts for WOOD EXTRUDED were about equal to that of the reference white cellulose acetate filter (about 20 counts each), with GCN REF being slightly higher (about 22 counts). Particle counts for WOOD and OLIVE STONE were considerably higher with counts between 100 and 200. The more highly activated coconut shell-derived activated carbon (GCN EXTRA) was substantially higher than any other activated carbon tested with total particle counts of around 350. As shown in FIG. 4, filters having activated carbon derived from cellulosic material and a binder (WOOD EXTRUDED) exhibited less particle breakthrough than activated carbon currently used in smoking article filters (GCN REF) and substantially less than coconut shell-derived activated carbon activated to a similar degree (GCN EXTRA).

(25) FIG. 5 shows particle breakthrough results for plug-space-plug configurations. As shown in FIG. 5, particle breakthrough tends to be higher in plug-space-plug filter configurations than in carbon on tow configurations. In the plug-space-plug configuration, particle breakthrough for the WOOD EXTRUDED activated carbon was higher than the control white filter, while no difference was seen between the two in the carbon on tow configuration. In the plug-space-plug configuration, WOOD EXTRUDED performed substantially better (less particle breakthrough) than GCN REF (about 190 vs. about 590, respectively).

(26) FIGS. 6-7 illustrate the ability of GCN REF and WOOD activated carbon filters to adsorb various smoke constituents in the plug-space-plug configuration (FIG. 6) and the ability of GCN REF and WOOD EXTRUDED activated carbon filters to adsorb various smoke constituents in the carbon on tow configuration (FIG. 7), relative to reference white cellulose acetate tow filters. As shown in both FIGS. 6 and 7, cigarettes having activated carbon in the filters were better able to reduce amounts of various smoke constituents than the filter without activated carbon (WHITE REF). FIGS. 6 and 7 also reveal that the WOOD EXTRUDED activated carbon performs about as well as the WOOD activated carbon. This can be derived because the WOOD in FIG. 6 performed about as well as the GCN REF in FIG. 6, and the WOOD EXTRUDED in FIG. 7 performed about as well as the GCN REF in FIG. 7. Accordingly the WOOD and WOOD EXTRUDED can be considered to perform similarly (as both perform similar to GCN REF). Accordingly, the presence of binder and extrusion does not appear to negatively affect the ability of WOOD EXTRUDED to adsorb smoke constituents.