METHOD FOR PRODUCING AN AEROSOL-FORMING SUBSTRATE AND AEROSOL-FORMING SUBSTRATE

Abstract

The invention relates to a method for producing an aerosol-forming substrate comprising: providing a cellulose based strengthening agent, providing a binder, mixing of hydroxypropylmethyl cellulose, water and an aerosol-former to form a first slurry, the first slurry having a viscosity of between 0.9 Pa s and 5 Pa s, and combining the cellulose based strengthening agent, the binder and the first slurry in order to obtain a final slurry, and drying the final slurry to obtain the aerosol-forming substrate. This method provides a first slurry having reduced viscosity and less water content.

Claims

1-15. (canceled)

16. A method for producing an aerosol-forming substrate comprising: providing a cellulose based strengthening agent, wherein the cellulose based strengthening agent is selected from a group consisting of: cellulose fibers, microcrystalline cellulose and cellulose powder, providing a binder, wherein the binder is selected from a group consisting of: methyl cellulose and carboxymethyl cellulose, mixing of hydroxypropylmethyl cellulose, water and an aerosol-former to form a first slurry, the first slurry having a viscosity of between 0.9 Pa.Math.s and 5 Pa.Math.s, and combining the cellulose based strengthening agent, the binder and the first slurry in order to obtain a final slurry, and drying the final slurry to obtain the aerosol-forming substrate.

17. The method according to claim 16, wherein the weight proportions of water:aerosol-former:hydroxypropylmethyl cellulose in the first slurry are 1:2 to 10:2 to 3.5, preferably wherein first water and aerosol-former are mixed in a weight proportion of water:aerosol-former of 1:2 to 10 and subsequently hydroxypropylmethyl cellulose is added in a weight proportion of hydroxypropylmethyl cellulose:aerosol-former of 1:1 to 3.

18. The method according to claim 16, wherein the cellulose based strengthening agent is cellulose fibers.

19. The method according to claim 16, wherein the aerosol-former is selected from a group consisting of: polyhydric alcohols, such as triethylene glycol, 1,3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, preferably wherein the aerosol-former is selected from a group consisting of: propylene glycol and glycerin, more preferably wherein the aerosol-former is glycerin.

20. The method according to claim 16, wherein the binder is carboxymethyl cellulose.

21. The method according to claim 16, wherein the cellulose based strengthening agent and water are mixed in weight proportions of cellulose fibers:water of 1:20 to 40 to form a second slurry and wherein the second slurry is combined with one or both of the first slurry or the binder.

22. The method according to claim 16, wherein the weight proportion of the second slurry:first slurry is 1:4 to 8, preferably 1:5 to 7, more preferably 1:6 to 6.5.

23. The method according to claim 16, wherein the binder is mixed with water to provide a third slurry, preferably wherein the weight proportion of binder:water is 1:30 to 200.

24. The method according to claim 16, wherein the first slurry, second slurry and third slurry are formed and wherein subsequently the slurries are mixed, preferably at a weight proportion of first slurry:second slurry:third slurry of 1:0.1 to 10:3 to 20, preferably 1:0.5 to 8:4 to 15.

25. The method according to claim 16, wherein nicotine is included in at least one of: the first slurry, the second slurry, the third slurry or the final slurry.

26. The method according to claim 16, wherein the aerosol-forming substrate is dried to a residual water content of between 5 weight percent and 15 weight percent based on the total weight of the aerosol-forming substrate.

27. A solid aerosol-forming substrate for use in an aerosol-generating system, the aerosol-forming substrate comprising: between 40 weight percent to 60 weight percent based on the total weight of the aerosol-forming substrate of an aerosol-former; between 12 weight percent to 25 weight percent based on the total weight of the aerosol-forming substrate of hydroxypropylmethyl cellulose; between 3 weight percent to 10 weight percent based on the total weight of the aerosol-forming substrate of a binder, wherein the binder is selected from a group consisting of: methyl cellulose and carboxymethyl cellulose, between 4 weight percent to 25 weight percent based on the total weight of the aerosol-forming substrate of a cellulose based strengthening agent, wherein the cellulose based strengthening agent is selected from a group consisting of: cellulose fibers, microcrystalline cellulose and cellulose powder, and water.

28. The aerosol-forming substrate according to claim 27, comprising between 16 weight percent to 23 weight percent of hydroxypropylmethyl cellulose.

29. The aerosol-forming substrate according to claim 27, comprising between 4 weight percent to 7 weight percent of binder.

Description

[0091] The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0092] FIG. 1 shows a graph depicting the viscosity of the first slurry in relation to the weight percentage of water;

[0093] FIG. 2 depicts a flow chart of the method for producing an aerosol-forming substrate in accordance with the present invention.

[0094] FIG. 1 shows a graph 10, wherein on the y-axis the viscosity of the first slurry in mPas.Math.s at a shear rate of 100 s.sup.?1 is plotted against the weight percent content of the water based on the total weight of the first slurry on the x-axis. The graph shows an optimum of between 10 to 25 weight percent of water, wherein the viscosity of the first slurry is the lowest. In part, the viscosity is in the range of 900 mPa.Math.s and 2800 mPa.Math.s, which is denoted with the reference numeral 12. The graph shows that at higher water contents of larger than 25 weight percent to around 50 weight percent the viscosity of the first slurry is surprisingly very high (area of high viscosity denoted with the reference numeral 14) which additionally also results in foaming when mixing the first slurry (area named foaming denoted with the reference numeral 16). Higher percentages of water of between 55 weight percent to 68 weight percent on the one hand decreases the viscosity again, but leads to the creation of agglomerates (area named lump creation denoted with the reference numeral 18). The dashed line denoted with 20 shows the viscosity of the guar glycerin reference mixture. This may be the reference mixture for which the mixing equipment was designed for. The guar glycerin reference mixture contains 5 weight parts of guar gum and 27 weight parts of glycerin.

[0095] FIG. 1 therefore shows that the inventors were able to identify a low amount of water included in the first slurry which on the one hand provides low viscosity and the other hand also avoids the problems of foaming and agglomeration. This is somehow surprising as a skilled person would expect that with increasing water content viscosity would be reduced. The low water content of between 10 to 25 weight percent of water also enables a quicker and easier drying of the final slurry in order to produce the aerosol-forming substrate.

[0096] FIG. 2 depicts a flow chart of the method of the present invention for producing the aerosol-forming substrate. Water and cellulose based strengthening agent, denoted with SA can be mixed in a first step in order to provide the second slurry. Preferably, cellulose fibers are employed as cellulose based strengthening agent. In a further step the binder, water and the aerosol-former, denoted with AF and optionally nicotine denoted with N and organic acid, denoted with OA are mixed in order to provide a third slurry. Preferably, carboxy methyl cellulose is employed as a binder and lactic acid as organic acid. In a further step, the hydroxypropylmethyl cellulose is added to a mixture of water and aerosol-former and mixed in order to provide the first slurry.

[0097] All the slurries, the first slurry, the second slurry and the third slurry are combined and mixed (see boxes denoted with transfer and mixing). Subsequently the final slurry is transferred to a buffer tank and finally casted, for example on a belt dryer for providing dried sheets of aerosol-forming substrate.

EXAMPLE

[0098] A first slurry was prepared with a weight proportion of water:glycerin:hydroxypropylmethyl cellulose of 3:10:5. Subsequently a second slurry was prepared with a weight proportion of cellulose fibers:water of 3.5:111. A third slurry containing carboxy methyl cellulose is prepared and added to the second slurry in a weight proportion of third slurry:second slurry of 1:114.5. The first slurry is subsequently added to the mixture of the third and second slurry for preparing the final slurry.