Metal carbide heat source

• US 5,040,552 A
• Filed: 12/08/1988
• Issued: 08/20/1991
• Est. Priority Date: 12/08/1988
• Status: Expired due to Term

• Current Assignee: Philip Morris Incorporated (Altria Group, Inc.)
• Original Assignee: Philip Morris Incorporated (Altria Group, Inc.)
• Inventors: Zhang, Yunchang, Schleich, Donald M.
• Primary Examiner(s): Millin, V.
• Application Number:
  US07/281,496
• Time in Patent Office: 985 Days
• Field of Search: 131/352, 131/359, 131/369, 131/194, 75/542
• US Class Current: 131/359
• CPC Class Codes: A24B 15/165 comprising as heat source a carbon fuel or an oxidized or thermally degraded carbonaceous fuel, e.g. carbohydrates, cellulosic material
• CPC Class Codes: A24D 1/22 Cigarettes with integrated combustible heat sources, e.g. with carbonaceous heat sources

Abstract

An iron carbide heat source, particularly useful in smoking articles, is provided. The iron carbide particles making up the heat source have ignition temperatures that are substantially lower than conventional carbon particles normally used in carbonaceous heat sources, while at the same time provide sufficient heat to release a flavored aerosol from a flavor bed for inhalation by the smoker. In a preferred embodiment, the iron carbide heat source of this invention is substantially cylindrical in shape and has one or more fluid passages therethrough. Upon combustion, the heat source produces substantially no carbon monoxide.

Claims

1. A heat source for use in a smoking article comprising iron carbide.

2. The heat source of claim 1 comprising metal carbide and carbon.

4. The heat source of any of claims 1, 2 and 3, wherein the metal carbide has the formula Fe₅ C₂.

5. The heat source of any of claims 1, 2 and 3, wherein the metal carbide has the formula Fe₃ C.

6. The heat source of any of claims 1, 2 and 3, wherein the heat source is substantially cylindrical in shape and has one or more fluid passages therethrough.

7. The heat source of claim 6, wherein the fluid passages are formed as grooves around the circumference of the heat source.

8. The heat source of claim 6, wherein the fluid passages are formed in the shape of a multi-pointed star.

9. The heat source of any of claims 1, 2 and 3, wherein the heat source contains at least one burn additive.

10. The heat source of any of claims 1, 2 and 3, wherein the metal carbide particles have a size of up to about 700 microns.

11. The heat source of any of claims 1, 2 and 3, wherein the metal carbide particles have a size in the range of submicron to about 300 microns.

12. The heat source of any of claims 1, 2 and 3, wherein the metal carbide particles have a B.E.T. surface area in the range of about 1 m² /gr to about 200 m² /gr.

13. The heat source of any of claims 1, 2 and 3, wherein the metal carbide particles have a B.E.T. surface area in the range of about 10 m² /gr to about 100 m² /gr.

14. The heat source of any of claims 1, 2 and 3, having a void volume of about 25% to about 75%.

15. The heat source of any of claims 1, 2 and 3, having a pore size of about 0.1 micron to about 100 microns.

16. The heat source of any of claims 1, 2 and 3, having a density of about 0.5 gr/cc to about 5 gr/cc.

17. The heat source of any of claims 1, 2 and 3, having a density of about 1.8 gr/cc to about 2.5 gr/cc.

18. The heat source of any claims 1, 2 and 3, having an ignition temperature of between about room temperature to about 550 degrees centigrade.

3. A heat source comprising iron carbide.