Homogenized tobacco material with improved volatile transfer

Abstract

There is provided a heated aerosol-generating article for producing an inhalable aerosol, the heated aerosol-generating article including: an aerosol-forming substrate that is a homogenized tobacco material including tobacco, a fat having a melting point between 20° C. and 50° C., and one or more aerosol-formers, the homogenized tobacco material containing at least 60% tobacco on a dry weight basis. A homogenized tobacco material is also provided.

Claims

1. An aerosol-generating article for producing an inhalable aerosol, the aerosol-generating article comprising: an aerosol-forming substrate that is a homogenized tobacco material comprising tobacco, a fat having a melting point between 20° C. and 50° C., one or more aerosol-formers, and reinforcement fibres with a mean fibre length of between 0.2 mm and 4.0 mm, wherein the homogenized tobacco material contains at least 60% tobacco on a dry weight basis, and wherein a total content of the one or more aerosol-formers in the homogenized tobacco material is between 5 weight percent and 20 weight percent on a dry weight basis.

2. The aerosol-generating article according to claim 1, wherein the aerosol-generating article further comprises a plurality of components, including the aerosol-forming substrate, assembled within a wrapper to form a rod having a mouth end and a distal end upstream from the mouth end.

3. The aerosol-generating article according to claim 1, wherein the fat is an oil.

4. The aerosol-generating article according to claim 1, wherein the homogenized tobacco material contains one or more fats selected from the group consisting of cocoa butter, palm oil, palm kernel oil, mango oil, shea butter, soybean oil, cottonseed oil, coconut oil, and hydrogenated coconut oil.

5. The aerosol-generating article according to claim 1, wherein the homogenized tobacco material contains at least 70% tobacco on a dry weight basis.

6. The aerosol-generating article according to claim 1, wherein the homogenized tobacco material contains between 70% and 80% tobacco on a dry weight basis.

7. The aerosol-generating article according to claim 1, wherein the homogenized tobacco material is tobacco powder having a mean particle size of between 0.03 mm and 0.12 mm.

8. The aerosol-generating article according to claim 1, wherein the one or more aerosol-formers is selected from the group consisting of propylene glycol, triethylene glycol, 1,3-butanediol, glycerine, glycerol monoacetate, glycerol diacetate, glycerol triacetate, dimethyl dodecanedioate, and dimethyl tetradecanedioate.

9. The aerosol-generating article according to claim 1, wherein the aerosol-forming substrate is a rod formed from a gathered sheet of the homogenized tobacco material.

10. The aerosol-generating article according to claim 1, wherein the homogenized tobacco material contains between 1 weight percent and 10 weight percent of the reinforcement fibres on a dry weight basis.

11. The aerosol-generating article according to claim 1, wherein the one or more aerosol-formers are selected from the group consisting of propylene glycol, triethylene glycol, 1,3-butanediol, glycerine, glycerol monoacetate, glycerol diacetate, glycerol triacetate, dimethyl dodecanedioate, and dimethyl tetradecanedioate, and wherein a total content of the one or more aerosol-formers in the homogenized tobacco material is between 5 weight percent and 20 weight percent on a dry weight basis.

12. The aerosol-generating article according to claim 1, wherein the homogenized tobacco material comprises a binder, and wherein a total content of lipid in the homogenized tobacco material is between 5 weight percent and 15 weight percent on a dry weight basis.

Description

(1) The invention will be further described, by way of example only, with reference to the accompanying drawing in which:

(2) FIG. 1 shows a flow diagram of a method to produce an homogenized tobacco material according to a specific embodiment of the invention.

(3) In a typical prior art process for manufacturing a web of reconstituted tobacco material, tobacco powder or dust is combined with cellulose fibres, a binder, and water to form a slurry. The slurry is then cast onto a moving belt and the slurry is dried to form the web of material. Such methods are well known to the skilled person. The slurry may further include other components, for example aerosol-formers such as glycerine. The cellulose fibres and the binder impart strength to the resulting homogenized tobacco material. A web intended for use as an aerosol-forming substrate in a heated aerosol-generating article may have a specific blend of tobacco and may have a high proportion of aerosol-former. As such, the web may have a low intrinsic strength. The strength of such a web may be increased by increasing the amount of cellulose fibre and binder.

(4) FIG. 1 is a flow diagram illustrating a general method for the production of homogenized tobacco material according to a specific embodiment of the present invention. The first step of the method is the selection 101 of the tobacco types and tobacco grades to be used in the tobacco blend for producing the homogenized tobacco material. Tobacco types and tobacco grades used in the present method are for example bright tobacco, dark tobacco, aromatic tobacco and filler tobacco.

(5) Further, the method includes a step 102 of coarse grinding of the tobacco leaves.

(6) After the coarse grinding step 102, a fine grinding step 103 is performed. The fine grinding step reduces the tobacco powder mean size to between about 0.03 millimetres and about 0.12. This fine grinding step 103 reduces the size of the tobacco down to a powder size suitable for the slurry preparation. After this fine grinding step 103, the cells of the tobacco are at least partially destroyed and the tobacco powder may become sticky.

(7) A lipid may be incorporated into the slurry as a solid phase or as a liquid phase. For example, where the lipid is a fat having a melting point between 20° C. and 40° C., it may be preferred to melt the fat at a temperature of about 40° C. The melted fat may then be added to the tobacco powder and a binder and mixed. The tobacco and fat mixture may then be added to water, reinforcement fibres and aerosol-former to form a slurry. Where the lipid has a melting point of higher than 40° C., for example most waxes, it may be preferred to form a slurry while the lipid is in the form of solid particles. The slurry may then be heated to the melting point of the lipid after slurry formation and prior to casting to distribute the lipid evenly throughout the slurry.

(8) Thus, the ground tobacco powder may be mixed with a lipid, an aerosol-former, a binder, and water to form a slurry 104. The lipid is preferably one or more fat selected from the list consisting of cocoa butter, palm oil, palm kernel oil, mango oil, shea butter, soybean oil, cottonseed oil, coconut oil, hydrogenated coconut oil, Preferably, the aerosol-former comprises glycerine, and preferably the binder comprises guar. In some embodiments the lipid may be a wax selected from the list consisting of candellila wax, carnauba wax, shellac, sunflower wax, rice bran, and Revel A.

(9) Preferably, the step of slurry formation 104 also comprises a mixing step, where all the slurry ingredients are mixed together for a fixed amount of time. The mixing step uses a high shear mixer. The slurry is then cast 105 onto a moving support, such as a steel conveyor belt. The slurry is preferably cast by means of a casting blade. The cast slurry is then dried 106 to form the homogenized tobacco web. The drying step 106 includes drying the cast web by means of steam and heated air. Preferably the drying with steam is performed on the side of the cast web in contact with the support, while the drying with heated air is performed on the free side of the cast web.

(10) Preferably, at the end of the drying step 106, the homogenized tobacco web is removed from the support 107. The homogenized tobacco web is preferably wound in one or more bobbins in a winding step 108, for example to form a single master bobbin. This master bobbin may be then used to perform the production of smaller bobbins by slitting and small bobbin forming process. The smaller bobbin may then be used for the production of an aerosol-generating article (not shown).

(11) The web of homogenized tobacco material may be used to form aerosol-forming substrates for use in aerosol-generating articles. For example, a sheet of the homogenized tobacco material may be gathered to form a rod of aerosol-forming substrate for use in a heated aerosol-generating article.

Experiment 1—Homogenized Tobacco Materials Comprising Fats

(12) In order to evaluate improvements in transfer of volatile components resulting from the incorporation of a lipid component into a homogenized tobacco material, a number of homogenized tobacco materials containing different low melting point lipids were formed and compared with a control homogenized tobacco material not containing a lipid.

(13) The control homogenized tobacco material comprised 65 wt % of tobacco powder, 20 wt % glycerine, 10 wt % water, 3 wt % guar, and 2 wt % cellulose fibres as reinforcement. The control homogenized tobacco material was formed by mixing the constituents into a slurry, casting the slurry and drying the slurry.

(14) A test material was formed using identical components to the control material, but varying the proportions of aerosol-former and tobacco powder, and including a proportion of cocoa butter. Other constituents of the homogenized tobacco material remain unchanged. Thus, a first homogenized tobacco material was formed comprising 63 wt % of tobacco powder, 12 wt % of a lipid in the form of cocoa butter, and 10 wt % of an aerosol-former in the form of glycerine was formed. Cocoa butter has a chemical abstracts service (CAS) number of CAS 8002-31-1 and a melting point of between 34-35° C.

(15) The homogenized tobacco material comprising cocoa butter was formed as described above. Specifically, the cocoa butter was melted at a temperature of 40° C. and the melted cocoa butter was mixed with the tobacco powder and the guar. This mixture was then added to the water, the cellulose fibres and the glycerine and mixed to form a homogenized slurry. The slurry was cast and dried to form a sheet of homogenized tobacco material.

(16) Further test materials were formed in identical fashion comprising palm oil (CAS 8002-75-3), shea butter (CAS 194043-92-0), and coconut oil (CAS 8001-31-8) instead of cocoa butter.

(17) Heated aerosol-generating articles were formed using each of the control homogenized tobacco material (control article alpha) and the four different test homogenized tobacco materials (test articles 1, 2, 3, and 4). Each of these different heated aerosol-generating articles was smoked under Health Canada conditions and the transfer rate of nicotine and glycerine was determined. Glycerine levels were determined according to CORESTA recommended method No. 60. Nicotine levels were determined according to ISO10315. Transfer rate was defined as (amount of substance delivered in aerosol)/(amount of substance present in the homogenized tobacco material). Transfer rate could alternatively be designated transfer efficiency. The results are shown in the table below.

(18) TABLE-US-00001 Transfer Transfer Rate Rate Glycerine Nicotine Control article alpha - 8.37% 24.95% homogenized tobacco material comprises 20% Glycerine and 65% Tobacco Test article 1 - homogenized 12.82% 30.02% tobacco material comprises 10% Glycerine, 12% Coca Butter, and 63% Tobacco Test article 2 - homogenized 13.14% 31.32% tobacco material comprises 10% Glycerine, 12% Palm Oil, and 63% Tobacco Test article 3 - homogenized 12.83% 30.24% tobacco material comprises 10% Glycerine, 12% Shea Butter, and 63% Tobacco Test article 4 - homogenized 11.99% 28.08% tobacco material comprises 10% Glycerine, 12% Coconut Oil, and 63% Tobacco

(19) It can be clearly seen that, under identical smoking conditions, homogenized tobacco materials having a lipid component produced a higher rate of glycerine transfer and a higher rate of nicotine transfer than a control homogenized tobacco material lacking a lipid component.

Experiment 2—Homogenized Tobacco Materials Comprising Waxes

(20) In order to evaluate improvements in transfer of volatile components resulting from the incorporation of a lipid component into a homogenized tobacco material, a number of homogenized tobacco materials containing different high melting point lipids were formed and compared with a control homogenized tobacco material not containing a lipid.

(21) The control homogenized tobacco material comprised 65 wt % of tobacco powder, 20 wt % glycerine, 10 wt % water, 3 wt % guar, and 2 wt % cellulose fibres as reinforcement. The control homogenized tobacco material was formed by mixing the constituents into a slurry, casting the slurry and drying the slurry.

(22) A test material was formed using identical components to the control material, but varying the proportions of aerosol-former and tobacco powder, and including a proportion of candellila wax. Other constituents of the homogenized tobacco material remain unchanged. Thus, a first homogenized tobacco material was formed comprising 63 wt % of tobacco powder, 12 wt % of a lipid in the form of candellila wax, and 10 wt % of an aerosol-former in the form of glycerine was formed. Candellila wax has a chemical abstracts service (CAS) number of CAS 8006-44-8 and a melting point of between 68.5-72.5° C.

(23) The homogenized tobacco material comprising candellila wax was formed as described above. Specifically, the candellila wax was mixed with the tobacco powder, the guar binder, the water, the cellulose fibres and the glycerine and mixed to form a slurry. The slurry was then heated to a temperature above the melting point of the candellila wax and mixed to form a homogenized slurry. The slurry was then cooled to a temperature of 40° C., cast and dried to form a sheet of homogenized tobacco material.

(24) Further test materials were formed in identical fashion comprising Revel A (CAS 68956-68-3), carnauba wax (CAS 8015-86-9), and rice bran (CAS 8016-60-2) instead of candellila wax.

(25) Heated aerosol-generating articles were formed using each of the control homogenized tobacco material (control article beta) and the four different test homogenized tobacco materials (test articles A, B, C, and D). Each of these different heated aerosol-generating articles was smoked under Health Canada conditions and the transfer rate of nicotine and glycerine was determined. Glycerine levels were determined according to CORESTA recommended method No. 60. Nicotine levels were determined according to ISO10315. Transfer rate was defined as (amount of substance delivered in aerosol)/(amount of substance present in the homogenized tobacco material). Transfer rate could alternatively be designated transfer efficiency. The results are shown in the table below.

(26) TABLE-US-00002 Transfer Transfer Rate Rate Glycerine Nicotine Control article beta - homogenized 5.01% 18.05% tobacco material comprises 20% Glycerine and 65% Tobacco Test article A - homogenized tobacco 7.52% 21.91% material comprises 10% Glycerine, 12% candellila wax, and 63% Tobacco Test article B - homogenized tobacco 7.79% 21.87% material comprises 10% Glycerine, 12% Revel A, and 63% Tobacco Test article C - homogenized tobacco 7.49% 21.73% material comprises 10% Glycerine, 12% carnauba wax, and 63% Tobacco Test article D - homogenized tobacco 6.67% 20.47% material comprises 10% Glycerine, 12% rice bran, and 63% Tobacco

(27) It can be clearly seen that, under identical smoking conditions, homogenized tobacco materials having a lipid component produced a higher rate of glycerine transfer and a higher rate of nicotine transfer than a control homogenized tobacco material lacking a lipid component.

(28) It is noted that the tobacco powder used in Experiment 2 was a different tobacco to that used in Experiment 1. Thus, the two control articles (article alpha and article beta) have different transfer rates of glycerine and nicotine. For both experiments, however, the rates of transfer were improved by the incorporation of a meltable lipid component into the homogenized tobacco material.