Smoking article with concentric filter

Abstract

A smoking article (10) incorporates a tobacco rob (12) and a filter attached to the tobacco rod. The filter includes a concentric filter segment (20) having a central core portion (23) with sorbent material and an outer periphery layer (24) circumscribed about the central core portion. At least about 80 weight % of the sorbent in the smoking article is disposed in the central core portion. The central core portion has a lower RTD than the periphery layer. A ventilation zone (30) is disposed adjacent an upstream end of the concentric sorbent segment.

Claims

1. A smoking article comprising: a tobacco rod; a filter attached to the tobacco rod by tipping paper, the filter comprising; a concentric sorbent segment including a central core portion and an outer periphery layer circumscribed about the central core portion, the outer periphery comprising filtration material formed of cellulose acetate, the central core portion being formed of paper and comprising a sorbent material comprising carbon material impregnated in the paper, the outer periphery layer and the central core portion being separated by an impermeable layer of material, the central core portion having a resistance to draw that is from 20% to 75% of a resistance to draw of the outer periphery layer, at least 80 weight % of the sorbent material in the smoking article is disposed in the central core portion; a second filter segment axially aligned with and between the tobacco rod and both of the central core portion and the outer periphery layer of the concentric sorbent segment; and a ventilation zone disposed upstream and within 3 mm of an upstream end of the concentric sorbent segment, the ventilation zone upstream and within 3 mm of the upstream end providing a dilution level of about 30% to 90%, the ventilation zone comprising a plurality of apertures or perforations formed in the tipping paper, wherein the ventilation zone is disposed along a length of the second filter segment.

2. A smoking article according to claim 1 wherein the concentric sorbent segment separates a third filter segment from the second filter segment.

3. A smoking article according to claim 2 wherein the third filter segment comprises cellulose acetate tow and the second filter segment comprises cellulose acetate tow.

4. A smoking article according to claim 1 wherein the central core portion has a lower density than the outer periphery layer.

5. A smoking article according to claim 1 wherein the smoking article comprises less than 25 mg of sorbent material.

6. A smoking article according to claim 1 wherein the sorbent material comprises activated carbon.

7. A smoking article according to claim 1 wherein the smoking article comprises less than 15 milligrams of activated carbon.

8. A smoking article according to claim 1 wherein the entire amount of the sorbent material in the smoking article is disposed in the central core portion of the smoking article.

9. A smoking article according to claim 1 further comprising a second ventilation zone disposed along the concentric sorbent segment.

10. A smoking article comprising: a tobacco rod; a filter attached to the tobacco rod by tipping paper, the filter comprising: a concentric sorbent segment including a central core portion being formed of paper and comprising a sorbent material comprising activated carbon and an outer periphery layer circumscribed about the central core portion, the outer periphery layer and the central core portion being separated by an impermeable layer of material, the central core portion having a resistance to draw that is from 20% to 75% of a resistance to draw of the outer periphery layer, at least 80 weight % of the sorbent material in the smoking article is disposed in the central core portion; a second filter segment axially aligned with and between the tobacco rod and both of the central core portion and the outer periphery layer of the concentric sorbent segment; and a ventilation zone disposed within 5 mm of an upstream end of the concentric sorbent segment, wherein the ventilation zone is disposed along a length of the second filter segment, the ventilation zone consisting of a plurality of apertures or perforations formed in the tipping paper.

11. A smoking article according to claim 10 wherein the smoking article comprises less than 15 milligrams of sorbent material.

12. A smoking article according to claim 10 wherein the filter comprises a third filter segment axially aligned with the concentric sorbent segment wherein the concentric sorbent segment separates the third filter segment from the second filter segment.

13. A smoking article according to claim 12 wherein the third filter segment comprises cellulose acetate tow and the second filter segment comprises cellulose acetate tow and the central core portion comprises a paper material impregnated with carbon material and the outer periphery layer comprises cellulose acetate tow.

14. A smoking article according to claim 10 further comprising a second ventilation zone disposed along the concentric sorbent segment.

Description

(1) The disclosure will be further described, by way of example only, with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a schematic cross section view of a smoking article according to the present disclosure having two filter segments; and

(3) FIG. 2 shows a schematic cross section view of a smoking article according to the present disclosure having three filter segments.

(4) The smoking article 10 shown in FIG. 1 and FIG. 2 includes a tobacco substrate or tobacco rod 12 attached to an axially aligned filter 11. The filter 11 is joined to the tobacco rod 12 with tipping paper 14. The tobacco rod 12 includes tobacco material 13 such as cut tobacco shreds.

(5) FIG. 1 illustrates a smoking article 10 having a concentric sorbent segment 20 and a second filter segment 15 in axial alignment with each other. The second filter segment 15 separates the tobacco rod 12 from the concentric sorbent segment 20. The concentric sorbent segment 20 has an upstream end 22 and a downstream end 21. The upstream end 22 extends toward the tobacco rod 12.

(6) FIG. 2 illustrates a smoking article 10 having three filter segments where the concentric sorbent segment 20 is in axial alignment and separates a second filter segment 15 and a third filter segment 17. The concentric sorbent segment 20 has an upstream end 22 and a downstream end 21. The upstream end 22 extends toward the tobacco rod 12.

(7) A ventilation zone 30 is disposed adjacent to the upstream end 22 of the concentric sorbent segment 20. The ventilation zone 30 is provided by a plurality of apertures or perforations formed in tipping paper 14 that is otherwise generally air impermeable. The ventilation zone 30 can circumnavigate the circumference of the smoking article 10. Positioning the ventilation zone 30 near or adjacent to the upstream end 22 of the concentric sorbent segment 20 appears to improve the efficiency of the sorbent material in the concentric sorbent segment 20. The ventilation zone 30 can be disposed within about 5 mm or within about 3 mm of the upstream end 22 of the concentric sorbent segment 20. In preferred embodiments, the ventilation zone 30 is disposed within about 5 mm or within about 3 mm upstream from the concentric sorbent segment 22 and along the length of the second filter segment 15, as illustrated.

(8) The filter 11 includes a concentric sorbent segment 20. The concentric sorbent segment 20 includes a central core portion 23 including a sorbent material and an outer periphery layer 24 circumscribed about the central core portion 23. The central core portion 23 has a lower resistance to draw or density than the periphery layer 24, as described above.

EXAMPLES

(9) A smoking article prototype (Example A) and a reference smoking article (Comparative Example) were similarly constructed except for the location of the ventilation zone. Example A and Comparative Example were then tested and the results are reported below.

(10) Example A and the Comparative Example were constructed as shown in FIG. 2 herein except the location of the ventilation zone was altered in the Comparative Example. The concentric sorbent segment included a central core portion formed of paper containing 8.4 mg of activated carbon. The periphery layer was formed of cellulose acetate and the second and third filter segments were formed of cellulose acetate. The central core portion exhibited an RTD of 780 mm WG and the periphery layer exhibited an RTD of 1600 mm WG. The concentric sorbent segment had a length of 12 mm and the second and third filter segments each had a length of 7.5 mm.

(11) Example A had ventilation located on the second filter segment and 2.5 mm from the upstream end of the concentric sorbent segment. Comparative Example had the ventilation zone located on the concentric sorbent segment and 4.5 mm from the downstream end of the concentric sorbent segment. Table 1 reports selected physical and analytical results for the Example A and Comparative Example.

(12) TABLE-US-00001 TABLE 1 Smoke Filter Total Filter TAR nicotine CO Diluation RTD RTD (mg/ (mg/ (mg/ (%) (mmH.sub.2O) (mmH.sub.2O) cig) cig) cig) Ex. A 49 96 96 5.7 0.48 8.2 Comp. Ex. 45 126 104 6.4 0.59 8.1

(13) Smoke constituent analysis was performed on both Example A and Comparative Example to evaluate the impact of the ventilation position on the carbon efficiency. Table 2 reports the means and standard deviations for both Example A and Comparative Example for analysed smoke constituents.

(14) TABLE-US-00002 TABLE 2 Standard Smoke constituent Deviation Diff (ug/mg SN) Comp Ex. A Comp Ex. A (Comp-Ex. A) Propionaldehyde 62.8 52.4 2.3 4.9 −10.3 Butyraldehyde 47.1 41.5 2.2 3.0 −5.6 Crotonaldehye 27.9 25.6 1.72 3.4 −2.3 Acetone 312.7 268.7 15.8 26.7 −44.0 Methylethylketone 75.2 66.7 3.7 6.3 −8.5 Acetaldehyde 772.2 637.8 27.5 42.3 −134.4 Acronlein 71.5 58.4 3.7 7.0 −13.1 Formaldehyde 41.7 35.5 2.5 3.3 −6.1 1,3-Butadien 72.2 58.6 3.7 3.3 −13.6 Benzene 67.5 57.0 2.7 2.9 −10.4 Isoprene 577.8 440.3 36.3 28.2 −137.5 Acrylonitrile 13.6 11.5 0.6 1.1 −2.0 Toluene 104.2 94.3 5.6 5 −9.9

(15) The results reported above indicate that the position of the ventilation zone upstream or near the upstream end of the concentric sorbent segment enhances the efficiency of the sorbent in the concentric filter segment.