TOBACCO SMOKE FILTER

• US 3,752,166 A
• Filed: 12/24/1970
• Issued: 08/14/1973
• Est. Priority Date: 12/24/1969
• Status: Expired due to Term

• Current Assignee: Harald David Mathewson, Henry Lyon, James Thomson Davidson Williamson, Stanley William Byrne
• Original Assignee: Harald David Mathewson, Henry Lyon, James Thomson Davidson Williamson, Stanley William Byrne
• Inventors: Lyon, Henry, Mathewson, Harald David, Williamson, James Thomson Davidson, Byrne, Stanley William
• Primary Examiner(s): Rein, Melvin D.
• Application Number:
  US05/101,295
• Time in Patent Office: 964 Days
• Field of Search: 131/10.3,10.5,10.7,10.9,264-269
• US Class Current: 131/340
• CPC Class Codes: A24D 3/0283 with means for a non-axial smoke flow

Abstract

A tobacco smoke filter, particularly for use with cigarettes, has a high filtration efficiency and novel construction, at least one end of the filter having an appearance similar to conventional filters comprising cylinders packed with crimped filaments or creped paper. The filter comprises a tube within which is a rod having an outer wall of filtering material and an inner part of supporting material. At one end the rod has the same cross sectional shape as the tube and is in engagement with the tube around its periphery, at the other end or between the ends, its cross sectional shape changes so that opposed surfaces of the filtering material engage each other, so that tobacco smoke drawn through the filter is constrained to pass through the wall of filtering material. The filter has a high efficiency at an acceptable pressure drop.

Claims

1. A tobacco smoke filter comprising:

a. an axially extending tubular outer member;

b. an axially extending air permeable rod disposed within said outer member;

c. said outer member including an inner surface and an outer surface and having spaced end portions;

d. said rod comprising an air permeable supporting part having at least one end face exposed for the passage of tobacco smoke therethrough;

e. a wall of air permeable filtering material circumferentially enclosing said supporting part said supporting part substantially completely filling said wall and having an outer circumferential surface and an inner surface;

f. at a first longitudinal position the circumferential surface of the wall of filtering material being in sealing engagement with the inner surface of said outer member throughout the entire periphery thereof so as substantially to preclude passage of smoke in the axial direction between the said circumferential surface And the said inner surface;

g. at a second position, longitudinally spaced from the first, portions of sealing said inner surface of the wall being in engagement with each other, so as substantially to preclude passage of smoke in the axial direction between the the sealed portions;

h. parts of the outer surface of said wall being spaced from the inner surface of said outer member to define a cavity, whereby smoke passing through said filter must travel through both said cavity and said wall of filtering material.

2. A tobacco smoke filter according to claim 1, the filtering material being an air permeable material selected from the group consisting of paper, bonded fibrous and filamentary webs, porous plastics, plastic foam, bonded fibres and bonded filaments.

3. A tobacco smoke filter according to claim 1, the rod comprising bonded fibres or filaments of cellulose acetate.

4. A tobacco smoke filter according to claim 1, the diameter of the fibres or filaments or the dimension of the inter pore material in the wall of the filtering material being not more than about 14 microns.

5. A tobacco smoke filter according to claim 1, the material of which the supporting part is made being selected from the group consisting of fibres, filaments, thermoplastic materials, creped paper, polyethylene and polypropylene.

6. A tobacco smoke filter according to claim 2, the wall being formed of a laminar material weighing between 40 and 100 g/m2.

7. A tobacco smoke filter according to claim 6 wherein the wall has an air permeability of between 2000 and 40,000 cc per minute per 10 cm2 under a pressure of 10 cm water gauge. *. A tobacco smoke filter according to claim 1 wherein the thickness of the wall lies between 0.05 mm and 0.4 mm.

9. Atobacco smoke filter according to claim 1 wherein the area of the outer circumferential wall exposed to the tobacco smoke lies between 2.0 and 7.0 cm2.

10. A tobacco smoke filter according to claim 1, the tubular outer member being of paper having a weight of not less than 45 g/m2.

11. A tobacco smoke filter according to claim 8, the wall of filtering material comprising paper weighing approximately 75 g/m2.

12. A tobacco smoke filter according to claim 1 wherein at least one of the said engaged surfaces is provided with an adhesive.

13. A tobacco smoke filter according to claim 1 wherein at the said second position the rod is formed into a plurality of ribs.

14. A tobacco smoke filter according to claim 13, the ribs being arranged in the form of a Y.

15. A tobacco smoke filter according to claim 1 wherein the said first position lies at one of the ends of the filter and the said second position lies at the other end of the filter.

16. A tobacco smoke filter according to claim 1 wherein the rod is in engagement with the outer member at its ends and that the said second position lies between its ends.

17. A tobacco smoke filter according to claim 16 wherein the wall of filtering material comprisies paper having an air porosity in excess of 30,000 cc per minute per 10 cm2 under a pressure of 10 cm water gauge.

18. A tobacco smoke filter according to claim 1 wherein the supporting part and the wall of filtering material are formed of continuous filamentary tows, the filaments of the tow forming the wall of filtering material being smaller than those forming the supporting part.

19. A tobacco smoke filter according to claim 16 wherein between the rod and the outer member a particulate filtering material is retained, at the said second position.

20. A cigarette comprising in combination a tobacco rod in end to end relationship with a tobacco smoke filter in accordance with claim 1.