Hydrophobic filter
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.
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 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 2 , and the hydrophobic groups have a basis weight in a range from about 0.1 to about 5 g/m 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 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 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 2 , and the hydrophobic groups have a basis weight in a range from about 0.1 to about 3 g/m 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.