Aerosol-generating system for generating nicotine salt particles

Abstract

An aerosol-generating system is provided, including a nicotine source; a volatile delivery enhancing compound source downstream of the nicotine source and including an acid; heating means for heating the nicotine source; and a physically separate heat transfer barrier between the nicotine source and the volatile delivery enhancing compound source. The heating means is configured to heat the nicotine source to a temperature of between about 80 C. and about 150 C. The heat transfer barrier is configured so that the temperature of the volatile delivery enhancing compound source is less than about 50 C. when the nicotine source is heated to a temperature of between about 80 C. and about 150 C. by the heating means.

Claims

1. An aerosol-generating system, comprising: a nicotine source; a volatile delivery enhancing compound source downstream of the nicotine source, wherein a volatile delivery enhancing compound of the volatile delivery enhancing compound source comprises an acid; heating means configured to heat the nicotine source to a temperature of between about 80 C. and about 150 C.; and a physically separate heat transfer barrier between the nicotine source and the volatile delivery enhancing compound source, wherein the physically separate heat transfer barrier is configured so that the temperature of the volatile delivery enhancing compound source is below about 60 C. when the nicotine source is heated to a temperature of between about 80 C. and about 150 C. by the heating means.

2. The aerosol-generating system according to claim 1, wherein the physically separate heat transfer barrier comprises a solid material or a gas, a vacuum or a partial vacuum, or a combination thereof.

3. The aerosol-generating system according to claim 1, wherein the physically separate heat transfer barrier comprises a solid material having a thermal conductivity of less than about 1 W per meter Kelvin (W/(m.Math.K)) at 23 C. and a relative humidity of 50%.

4. The aerosol-generating system according to claim 2, wherein the physically separate heat transfer barrier further comprises a cavity having a length of at least about 8 mm.

5. The aerosol-generating system according to claim 1, wherein the nicotine source comprises a first sorption element and nicotine sorbed on the first sorption element.

6. The aerosol-generating system according to claim 5, wherein the volatile delivery enhancing compound source comprises a second sorption element and the volatile delivery enhancing compound sorbed on the second sorption element.

7. The aerosol-generating system according to claim 1, wherein the volatile delivery enhancing compound acid comprises a carboxylic acid.

8. The aerosol-generating system according to claim 1, wherein the acid is selected from the group consisting of 3-methyl-2-oxovaleric acid, pyruvic acid, 2-oxovaleric acid, 4-methyl-2-oxovaleric acid, 3-methyl-2-oxobutanoic acid, 2-oxooctanoic acid, lactic acid, and combinations thereof.

9. The aerosol-generating system according to claim 1, wherein the acid is pyruvic acid or lactic acid.

10. The aerosol-generating system according to claim 1, further comprising a housing comprising an air inlet and an air outlet, the housing further comprising in series from air inlet to air outlet: a first compartment comprising the nicotine source in communication with the air inlet; a second compartment comprising the volatile delivery enhancing compound source in communication with the first compartment; and the physically separate heat transfer barrier disposed between the first compartment and the second compartment, wherein the air inlet and the air outlet are in communication with each other and are configured so that air may pass into the housing through the air inlet, through the housing, and out of the housing through the air outlet.

11. The aerosol-generating system according to claim 10, wherein one or both of the first compartment and the second compartment are sealed by one or more frangible barriers.

12. The aerosol-generating system according to claim 11, further comprising a piercing element configured to pierce the one or more frangible barriers sealing one or both of the first compartment and the second compartment.

13. The aerosol-generating system according to claim 1, further comprising: an aerosol-generating article comprising the nicotine source, the volatile delivery enhancing compound source, and the physically separate heat transfer barrier.

14. The aerosol-generating system according to claim 13, further comprising: an aerosol-generating device in cooperation with the aerosol-generating article, the aerosol generating device comprising the heating means configured to heat the nicotine source of the aerosol-generating article.

Description

(1) The invention will now be further described with reference to the accompanying drawing in which:

(2) FIG. 1 shows a schematic longitudinal cross-section of an aerosol-generating system according to an embodiment of the invention.

(3) FIG. 1 schematically shows an aerosol-generating system according to an embodiment of the invention comprising an aerosol-generating article 2 and an aerosol-generating device 4.

(4) The aerosol-generating article 2 has an elongate cylindrical housing comprising a first compartment 6 comprising a nicotine source, a heat transfer barrier 8, a second compartment 10 comprising a volatile delivery enhancing compound source, a third compartment 12 and a mouthpiece 14. As shown in FIG. 1, the first compartment 6, the heat transfer barrier 8, the second compartment 10, the third compartment 12 and the mouthpiece 14 are arranged in series and in coaxial alignment within the aerosol-generating article 2. The first compartment 6 is located at the distal end of the aerosol-generating article 2. The second compartment 10 is located downstream of the first compartment 6. The heat transfer barrier 8 is located between the first compartment 6 and the second compartment 10. The third compartment 12 is located immediately downstream of the second compartment 10. The mouthpiece 14 is located immediately downstream of the third compartment 10 at the proximal end of the aerosol-generating article 2.

(5) The upstream and downstream ends of the first compartment 6 and the second compartment 10 of the aerosol-generating article 2 are sealed by frangible aluminium foil barriers (not shown).

(6) The aerosol-generating device 4 comprises a housing comprising an elongate cylindrical cavity in which the aerosol-generating article 2 is received. The length of the cavity is less than the length of the aerosol-generating article 2 so that the proximal end of the aerosol-generating article 2 protrudes from the cavity.

(7) The aerosol-generating device 4 further comprises a power supply 16, a controller (not shown), heating means 18, and a piercing element 20. The power supply 16 is a battery and the controller comprises electronic circuitry and is connected to the power supply 16 and the heating means 18.

(8) The heating means 18 comprises an external heating element positioned about the perimeter of a portion of the cavity at the distal end thereof and extends fully around the circumference of the cavity. As shown in FIG. 1, the external heating element is positioned so that it circumscribes the first compartment 6 and an upstream portion of the heat transfer barrier 8 of the aerosol-generating article 2.

(9) The piercing element 20 is positioned centrally within the cavity of the aerosol-generating device 4 and extends along the major axis of the cavity.

(10) In use, as the aerosol-generating article 2 is inserted into the cavity of the aerosol-generating device 4 the piercing element 20 is inserted into the aerosol-generating article 2 and pierces the frangible barriers (not shown) at the upstream and downstream ends of the first compartment 6 and the second compartment 10 of the aerosol-generating article 2. This allows a user to draw air into the housing of the aerosol-generating article through the distal end thereof, downstream through the first compartment 6, the heat transfer barrier 8, the second compartment 10 and the third compartment 12 and out of the housing through the mouthpiece 14 at the proximal end thereof.

(11) Nicotine vapour is released from the nicotine source in the first compartment 6 into the air stream drawn through the aerosol-generating article 2 and volatile delivery enhancing compound vapour is released from the volatile delivery enhancing compound source in the second compartment 10 into the air stream drawn through the aerosol-generating article 2. The nicotine vapour reacts with the volatile delivery enhancing compound vapour in the gas phase in the second compartment 10 and the third compartment 12 to form an aerosol, which is delivered to the user through the mouthpiece 14 at the proximal end of the aerosol-generating article 2.

(12) In use, the heat transfer barrier 10 reduces heat transfer from the first compartment 6 to the second compartment 10 as the first compartment is heated by the heating means 18 so that the second compartment 10 of the aerosol-generating article 2 is maintained at a lower temperature than the first compartment 6.

(13) The first compartment 6 of the aerosol-generating article 2 comprises a nicotine source comprising a porous sorption element with 10 mg of nicotine sorbed thereon, the heat transfer barrier 8 of the aerosol-generating article 2 comprises an air-filled cavity, and the second compartment 10 of the aerosol-generating article 2 comprises a pyruvic acid source comprising a porous sorption element with 20 mg of pyruvic acid sorbed thereon. The first compartment 6, the heat transfer barrier 8 and the second compartment 10 of the aerosol-generating article 2 are each about 10 mm in length. The third compartment 12 of the aerosol-generating article 2 is about 25 mm in length. The mouthpiece 14 of the aerosol-generating article 2 is about 10 mm in length. The total length of the aerosol-generating article 2 is about 85 mm.

(14) The external heating element of the heating means 18 of the aerosol-generating device 4 is about 15 mm in length. The heating means 18 is configured to heat the first compartment 6 to a temperature of less than about 110 C. In use a constant power supply is provided to the heating means 18 so as to heat the exterior of the first compartment 6 to a temperature of between about 100 C. and about 110 C. over a period of about 150 seconds and to then maintain the temperature within this range for a period of at least 200 seconds.

(15) Due to inclusion of the heat transfer barrier 8, the second compartment 10 of the aerosol-generating article 2 is maintained at a temperature of less than about 45 C. during heating of the first compartment 6 by the heating means 18. To demonstrate this, temperature measurements are taken using first and second temperature sensors during heating of the first compartment 6 by the heating means 18 over a period of 6 minutes starting upon initiation of the heating means 18. The first and second temperature sensors are attached to the exterior of the first and second compartments, respectively, approximately half-way along the length thereof. The results are shown in Table 1.

(16) TABLE-US-00001 TABLE 1 Temperature of Temperature of Time (seconds) first compartment ( C.) second compartment ( C.) 0 26 25 30 65 25 60 82 27 90 92 30 120 98 33 150 101 35 180 103 37 210 105 38 240 106 39 270 106 40 300 107 41 330 107 42 360 107 43

(17) The average nicotine delivery (g/puff) of the aerosol-generating system according to the embodiment of the invention shown in FIG. 1 is measured as a function of puff number during operation of the aerosol-generating system according to a Health Canada Intense smoking regime (55 cm.sup.3 puff volume, 30 second puff frequency, 2 second puff duration and 100% vent blocking).

(18) For the purpose of comparison, the average nicotine delivery (g/puff) of a reference aerosol-generating system not according to the invention as a function of puff number during operation of the aerosol-generating system according to a Health Canada Intense smoking regime (55 cm.sup.3 puff volume, 30 second puff frequency, 2 second puff duration and 100% vent blocking) is also measured. The reference aerosol-generating system differs from the aerosol-generating article according to FIG. 1 in that the position of the pyruvic acid source and the nicotine source are reversed such that the first compartment comprises the pyruvic acid source and the second compartment comprises the nicotine source. The aerosol-generating article of the reference aerosol-generating system thus comprises a first compartment comprising a pyruvic acid source comprising a porous sorption element with 20 mg of pyruvic acid sorbed thereon and a second compartment comprising a nicotine source comprising a porous sorption element with 10 mg of nicotine sorbed thereon.

(19) The average nicotine delivery (g/puff) of the aerosol-generating system according to the invention, which comprises an aerosol-generating article comprising a nicotine source, a volatile delivery enhancing compound source downstream of the nicotine source and a heat transfer barrier between the nicotine source and the volatile delivery enhancing compound source, increases with increasing puff number. The increasing puff per puff nicotine delivery of the aerosol-generating system according to the invention is similar to the increasing puff per puff nicotine delivery of conventional lit-end cigarettes.

(20) The average nicotine delivery (g/puff) of the reference aerosol-generating system, which comprises an aerosol-generating article comprising a nicotine source and a volatile delivery enhancing compound immediately upstream of the nicotine source, is significantly lower than the nicotine delivery of the aerosol-generating system according to the invention. Furthermore, in contrast to the aerosol-generating system according to the invention and conventional lit-end cigarettes, the average nicotine delivery (g/puff) of the reference aerosol-generating system decreases with increasing puff number.