Hydrophobic filter

Abstract

A smoking article includes a smokable material and a filter comprising filtration material that is downstream of the smokable material. The filtration material comprises a sheet of hydrophobic cellulosic material with hydrophobic groups covalently bonded to the cellulosic material.

Claims

1. A smoking article comprising: a smokable material; and a filter downstream of the smokable material and comprising filtration material, the filtration material comprising a sheet of paper comprising hydrophobic groups covalently bonded to cellulosic material of the paper, wherein the hydrophobic group is formed by reacting a fatty acid group with a protogenic group of the cellulosic material, and wherein the sheet of paper is crimped along a longitudinal direction of the sheet and gathered transversely to form a cylindrical filter element.

2. The smoking article according to claim 1, wherein the crimped sheet of paper comprises parallel and co-extensive ridges and valleys along a longitudinal length of the crimped sheet, wherein the pitch measured in a transverse direction that is perpendicular to the direction of travel is about 1 mm.

3. The smoking article according to claim 1, wherein the width of the sheet of paper is about 150 mm to about 250 mm.

4. The smoking article according to claim 1, wherein diameter of the filter is about 4.5 mm to about 9.5 mm.

5. The smoking article according to claim 1, wherein the sheet of paper has a water contact angle of at least about 90 degrees.

6. The smoking article according to claim 1, wherein the sheet of paper exhibits a Cobb water absorption measurement value (at 60 seconds) of about 40 g/m.sup.2.

7. The smoking article according to claim 1, wherein the sheet of paper has a basis weight in a range from about 20 to about 60 g/m.sup.2, and the hydrophobic groups have a basis weight in a range from about 0.1 to about 5 g/m.sup.2.

8. The smoking article according to claim 1, wherein the hydrophobic group comprises a fatty acid or fatty acid ester.

9. The smoking article according to claim 1, wherein the sheet of paper comprises fatty acid esters of cellulose.

10. The smoking article according to claim 1, wherein the hydrophobic group is covalently bonded to the cellulosic material by diffusion of a fatty acid halide on its surface without using a solvent.

11. The smoking article according to claim 10, wherein the fatty acid halide comprises palmitoyl chloride, stearoyl chloride, behenoyl chloride, or a mixture of palmitoyl chloride and stearoyl chloride.

12. A filter for a smoking article comprising: a continuous sheet of paper distributed through a cross-section of a cylindrical filter element, the continuous sheet of paper comprising hydrophobic groups covalently bonded to cellulosic material of the continuous sheet of paper, wherein the hydrophobic group is formed by reacting a fatty acid group with a protogenic group of the cellulosic material, and wherein the continuous sheet of paper is crimped along a longitudinal direction of the sheet and gathered transversely to form a cylindrical filter element, the continuous sheet of paper having a water contact angle of at least about 90 degrees and a Cobb measurement value (at 60 seconds) of about 40 g/m.sup.2 or less.

13. The filter according to claim 12, wherein the continuous sheet of paper has hydrophobic groups covalently bonded to protogenic groups on the paper.

14. The filter according to claim 12, wherein the continuous sheet of paper is crimped is arranged in layers that are packed to form a cylindrical filter element.

15. The smoking article according to claim 2, wherein the crimped sheet of paper comprises parallel and co-extensive ridges and valleys along a longitudinal length of the crimped sheet, wherein the pitch measured in a transverse direction that is perpendicular to the direction of travel is about 1 mm.

16. The smoking article according to claim 1, wherein the sheet of paper has a water contact angle of at least about 100 degrees, and the sheet of hydrophobic cellulosic material exhibits a Cobb water absorption measurement value (at 60 seconds) of 35 g/m.sup.2 or less.

17. The smoking article according to claim 1 wherein the sheet of paper has a basis weight in a range from about 30 to about 45 g/m.sup.2, and the hydrophobic groups have a basis weight in a range from about 0.1 to about 3 g/m.sup.2.

18. The filter according to claim 12, wherein the continuous sheet of paper has fatty acid or fatty acid ester groups covalently bonded to the paper.

Description

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

(2) FIG. 2 is a schematic perspective view of an illustrative continuous sheet of hydrophobic material;

(3) FIG. 3 is a schematic cross-sectional view of an illustrative filter element; and

(4) FIG. 4 is a graph of the relationship between width of paper before crimping (180 mm to 220 mm), the two levels of crimping, and the RTD.

(5) The smoking articles depicted in FIGS. 1-3 illustrate one or more 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.

(6) Referring now to FIG. 1, a smoking article 10 is depicted. The smoking article 10 includes a tobacco substrate 20, such as a tobacco rod, and a mouth end segment 30 and a lit end tip 70. The mouthpiece includes a filter element 30 and can abut the tobacco substrate 20 in the finished smoking article 10. The depicted smoking article 10, includes a plug wrap 60 that circumscribes at least a portion of the filter or mouthpiece segment 30 and a wrapper 40 that circumscribes at least a portion of the tobacco substrate 20. A tipping paper 50 circumscribes the plug wrap 60 and a portion of the wrapper 40.

(7) FIG. 2 illustrates a continuous sheet of hydrophobic cellulosic material 101 defining an crimped structure portion 120 with ridges and valleys that are parallel to the direction of transport (see the direction of the arrow) of the material in a crimping unit. An illustrative planar portion 110 is also shown.

(8) FIG. 3 illustrates a cross-sectional view of one embodiment of the hydrophobic filter element 130. The crimped sheet of hydrophobic cellulosic material 101 is illustrated as being folded upon itself and packed into a cylindrical space with a substantially circular cross-section. Plug wrap 160 surrounds and secures the sheet of hydrophobic cellulosic material 101 in a cylindrical form.

(9) The exemplary embodiments described above are not limiting. Other embodiments consistent with the exemplary embodiments described above will be apparent to those skilled in the art.