EP4651740A1

EP4651740A1 - Tobacco product and a method of manufacture thereof

Info

Publication number: EP4651740A1
Application number: EP24700618.2A
Authority: EP
Inventors: Cecile Sinkinson; Oswaldo ANGUIANO
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2023-01-16
Filing date: 2024-01-15
Publication date: 2025-11-26
Also published as: CN120456830A; JP2025541517A; KR20250122506A; WO2024153575A1

Abstract

A method of manufacturing a fire repellent reconstituted tobacco component is disclosed, the method comprising the steps of: grinding a tobacco material to produce ground tobacco fibres; treating the ground tobacco fibres by applying a treatment comprising a donor of a phosphorous group, wherein the donor of the phosphorous group comprises an inositol phosphate moiety; heating the treated tobacco fibres to obtain phosphorous-treated tobacco fibres; and processing the phosphorous-treated tobacco fibres to produce the fire repellent reconstituted tobacco component.

Description

TOBACCO PRODUCT AND A METHOD OF MANUFACTURE THEREOF

FIELD OF INVENTION

The present invention relates to tobacco products, and specifically the manufacture of a fire repellent reconstituted tobacco component for heat-not-burn use.

BACKGROUND

Aerosol generating articles usually heat a consumable in order to generate an aerosol or vapour for user inhalation. In the past tobacco products such as conventional cigarettes have been burnt or combusted in order to create a tobacco smoke. More recently, heat-not-burn (HnB) products have been developed which do not require combustion of the tobacco consumable.

Known regulations require an entire HnB tobacco product to not be combustible. For example, a heated tobacco stick cannot be lit as a conventional cigarette. Known HnB products thus use metallised wrappers or cigarette paper that has been treated with additives in order to be non-combustible and fire-retardant. Such technologies are often non-biodegradable and can be toxic to humans or animals.

An object of the invention is to provide an effective fire repellent reconstituted tobacco component for heat-not-burn uses.

SUMMARY OF INVENTION

According to an aspect of the invention, there is provided a method of manufacturing a fire repellent reconstituted tobacco component, the method comprising: grinding a tobacco material to produce ground tobacco fibres; treating the ground tobacco fibres by applying a treatment comprising a donor of a phosphorous group, wherein the donor of the phosphorous group comprises an inositol phosphate moiety; heating the treated tobacco fibres to obtain phosphorous-treated tobacco fibres; and processing the phosphorous-treated tobacco fibres to produce the fire repellent reconstituted tobacco component.

In this way, a non-combustible heat-not-burn (HnB) aerosol generating consumable is provided with fire repellent properties and that is non-toxic and biodegradable. It has been advantageously found that grinding the tobacco material and treating the ground tobacco fibres before making the reconstituted tobacco component (as opposed to treating the reconstituted tobacco component after it is made) significantly improves the covalent bonding of the donors of the phosphorous groups to the tobacco fibres. When the phosphorous compound is in the treatment solution, a donor of the phosphorous group is yet to bond or graft to the tobacco fibres. After treatment (i.e. after the chemical reaction in which the donors of the phosphorous groups bond to the tobacco fibres), the phosphorous group(s) is bonded/grafted to the tobacco fibres (thus providing treated tobacco fibres). The fire repellent reconstituted tobacco component, also known as a reconstituted tobacco blend (RTB), may comprise 0.1 to 10 % phosphorous groups by weight of the total weight of the reconstituted tobacco component, preferably between 0.5 to 3 %.

Advantageously, the fire repellent reconstituted tobacco of the claimed invention chars and does not ignite when heated. The phosphorous groups that have grafted onto the tobacco promote carbonization of the tobacco fibres at high temperatures which forms a protective char layer which acts as a fire retardant. The level, or degree, or charring may vary from 15 to 40 %, preferably between 15 to 20 %.

Preferably, the ground tobacco fibres comprise microfibres having an average diameter less than 400 pm (microns), and/or nanofibres having an average diameter of less than 500 nm (nanometres). In this way, an optimal average diameter of the ground tobacco fibres ensures that a suitable amount of the phosphorous groups are bonded to the tobacco fibres to ensure an effective fire repellent reconstituted tobacco component. It has also been found that grinding the tobacco material to have an average diameter across the fibres also ensures a more homogenised tobacco fibre distribution which improves the ease of forming the fire repellent reconstituted tobacco component. The grinding may be performed by a mechanical dispersion mill and a homogenizer.

The donor of the phosphorous group comprises an inositol phosphate moiety. For example, phytic acid is a donor of phosphorous groups which has an inositol phosphate moiety. Other examples include: D-myo-lnositol 1 , 4, 5-th phosphate tripotassium salt, and D-myo-lnositol 1 , 3, 4, 5-tetrakis(phosphate) ammonium salt. As will be appreciated by the skilled person, other phosphorus based compounds may also be used as a donor of a phosphorous group.

It has been advantageously found that inositol phosphorus based derivatives/moieties allow multiple phosphorous groups from a same inositol phosphorus based derivative to be grafted to multiple tobacco fibres. In other words, one inositol phosphorus based derivative allows multiple covalent bonds to be formed between the inositol phosphate derivative and a tobacco fibre. In this way, the amount of treatment solution required to get ensure effective fire repellent properties can be decreased, thus improving the ease and cost of manufacture of the fire repellent reconstituted tobacco component I RTB.

Preferably, the treatment solution comprises 0.1 to 20 % of an inositol phosphate derivative, such as for example phytic acid (PA), by weight of the total weight of the treatment solution, preferably 3 to 10 %. Preferably, the inositol phosphate derivative comprises phytic acid. In this way, the phosphorous group of the inositol phosphate derivative is able to catalyse the carbonisation of the tobacco material fibres to form a dense and protective char layer on the tobacco fibre surface. This protective layer hinders heat transfer between adjacent and surrounding tobacco fibres, which in turn provides the fire repellent properties of the reconstituted tobacco component. Most preferably, the treatment solution comprises 0.1 to 20 % of phytic acid (PA) by weight of the total weight of the treatment solution, preferably 3 to 10 %. Preferably, the treatment solution comprises 1 to 40 % urea by weight of the total weight of the treatment solution, preferably between 10 to 20 %. In this way, the treatment application step urea acts as an enabler which improves the accessibility of the phosphorous groups in the inositol phosphate derivative, such as for example phytic acid, to the individual tobacco fibres and ensure effective covalent bonding. The urea also protects the tobacco fibre material from degradation after the solution-treatment when it is heated at a later stage (e.g. to dry the pulp before it is heated or made into paper).

The application of the ground tobacco fibres with the treatment solution may be performed by soaking the tobacco fibres in the treatment solution or spraying the treatment solution onto the ground tobacco fibres.

Preferably, the ratio of ground tobacco fibres to treatment solution is between 1 :1 to 1 :10, most preferably 1 :5. In this way, the wetting of the tobacco fibres can be efficiently performed as well as ensuring that the tobacco fibres are effectively treated.

Preferably, treating the ground tobacco fibres comprises a soaking process or a spraying process. Preferably, when the ground tobacco fibres are treated by soaking, the treating of the ground tobacco fibres further comprises a drying step performed after the soaking process, said drying step being realised under atmospheric condition between 5 minutes to 8 hrs, preferably between 15 mins to 30 mins, and at a temperature ranging from 15 °C to 60 °C (degrees Celsius), preferably ranging from 40 °C to 60 °C. A moisture content of the treated tobacco fibres after the drying step ranges from 5 to 20 % by weight of the total weight of the treated ground tobacco fibres.

Preferably, the treated tobacco fibres are heated at 140 to 200 °C. Heating the tobacco fibre-treatment solution mixture ensures that the donors of the phosphorous groups in the solution can effectively covalently bond to the tobacco fibres. Preferably, prior to applying the treatment solution, the method further comprises a step of using steam explosion of the ground tobacco fibres to obtain nanofibres having an average diameter of less than 500 nm. Preferably, the plant tobacco fibres are tobacco stems. In this way, tobacco nanofibres having an average diameter of less than 500 nm (nanometres) are obtained. Advantageously, these tobacco nanofibres can be used to improve the mechanical properties of the final fire repellent reconstituted tobacco material, such as for example the resistance and the filling power of the final fire repellent reconstituted tobacco sheet. These tobacco nanofibres also provide an enhanced tobacco taste. The tobacco material is pre-treated such that the smaller or nanofibers can be more easily obtained. Tobacco fibres obtained through steam, or vapour, explosion may have a diameter between 50 to 500 nm, preferably between 50 to 100 nm.

Preferably, the method further comprises a step of refining the ground tobacco fibres. In this way, the ground tobacco fibres can be “grated” to produce fibrils. The refining step may be performed by passing the tobacco fibres through a disc refiner, such that the fibrils are formed as the tobacco fibres pass between the blades of the disc refiner.

It has been found that the fibrils enhance the bonding I grafting process (i.e. the treatment with the donor of the phosphorous group solution). The fibrils also provide an improved “clinging” of the tobacco fibres to each other (e.g. by electrostatic forces), which in turn improves the homogeneity of the distribution of the tobacco fibres when forming the fire repellent reconstituted tobacco component.

Preferably, prior to the grinding step, the method further comprises a step of mixing tobacco leaves with water to form a tobacco mixture; and dehydrating the tobacco mixture to obtain a tobacco concentrate and the tobacco material for grinding, wherein the tobacco concentrate is recombined with the phosphorous- treated tobacco fibres in the processing step. According to another aspect of the invention, there is provided a fire repellent reconstituted tobacco component, the fire repellent reconstituted tobacco component comprising 0.1% to 10% phosphorous groups by weight of the total weight of the reconstituted tobacco component, preferably 0.5 % to 3 %, and wherein the phosphorous groups comprise an inositol phosphate moiety.

Preferably, the phosphorous groups are covalently grafted to ground tobacco plant fibres of the reconstituted tobacco component. Examples include phytic acid (inositol hexaphosphate) or phytate as a salt, D-myo-lnositol 1 , 4, 5-triphosphate tripotassium salt, and /pr D-myo-lnositol 1 , 3, 4, 5-tetrakis(phosphate) ammonium salt.

Preferably, the fire repellent reconstituted tobacco component comprises ground tobacco fibres comprising microfibres having an average diameter less than 400 microns, and/or nanofibres having an average diameter of less than 500 nm.

According to another aspect of the invention, there is provided an aerosol generating article for use with a heat-not-burn aerosol generating device. The aerosol generating article comprises an aerosol-generating substrate. The aerosol-generating substrate comprises a tobacco component wrapped in cigarette paper to form a tobacco rod. The tobacco component comprises the fire repellent reconstituted tobacco as above defined. In particular, the fire repellent reconstituted tobacco comprises 0.1 % to 10% of phosphorous groups by weight of the total weight of the fire repellent reconstituted tobacco, preferably 0.5% to 3%, and wherein the phosphorous groups comprise an inositol phosphate moiety.

The aerosol generating article may further comprise a downstream section extending from a downstream end of the aerosol-generating substrate to a downstream end of the aerosol-generating article. The downstream section can also be called the mouth end. The downstream section may comprise one or more downstream elements or segments, including: a filter plug, a centre hole, a support tube (which may comprise paper), an aerosol cooling section, and/or a mouthpiece. The downstream elements may be arranged downstream of, and preferably adjacent to, the aerosol generating substrate of the aerosol generating article, such that in use the aerosol generated from the aerosol-generating substrate upon the application of heat, flows through the downstream section to be inhaled by a user.

Preferably, the aerosol generating article comprises an aerosol-generating substrate including the fire repellent reconstituted tobacco as above defined. In particular, the fire repellent reconstituted tobacco comprises 0.1 % to 10% of phosphorous groups by weight of the total weight of the fire repellent reconstituted tobacco, preferably 0.5% to 3%. The aerosol generating article also comprises a downstream section including an aerosol cooling section adjacent to the downstream end of the aerosol-generating substrate and a mouthpiece adjacent to the downstream end of the aerosol cooling section. Most preferably, the aerosol cooling section may be a paper tube or a section comprising a crimped polylactic acid sheet. Most preferably, the mouthpiece comprises a filter plug.

Preferably, the aerosol generating article comprises an aerosol-generating substrate including the fire repellent reconstituted tobacco as above defined. In particular, the fire repellent reconstituted tobacco comprises 0.1 % to 10% of phosphorous groups by weight of the total weight of the fire repellent reconstituted tobacco, preferably 0.5% to 3%. The aerosol generating article also comprises a downstream section including an aerosol cooling section adjacent to the downstream end of the aerosol-generating substrate, a centre hole adjacent to the downstream end of the aerosol cooling section and a mouthpiece adjacent to the downstream end of the centre hole. Most preferably, the aerosol cooling section may be a paper tube or a section comprising a crimped polylactic acid sheet. Most preferably, the mouthpiece comprises a filter plug.

Preferably, the aerosol generating article comprises an aerosol-generating substrate including the fire repellent reconstituted tobacco as above defined. In particular, the fire repellent reconstituted tobacco comprises 0.1 % to 10% of phosphorous groups by weight of the total weight of the fire repellent reconstituted tobacco, preferably 0.5% to 3%. The aerosol generating article also comprises a downstream section including a first centre hole having a first inner diameter adjacent to the downstream end of the tobacco component, a second centre hole having a second inner diameter adjacent to the downstream end of the first centre hole and a mouthpiece adjacent to the downstream end of the second centre hole. Most preferably, the first inner diameter is smaller than the second inner diameter. The first inner diameter may be ranging from 1 ,5 mm (millimetre) and 4,5 mm. The second diameter may be ranging from 3,5 mm to 6,0 mm. Most preferably, the mouthpiece comprises a filter plug.

Preferably, the aerosol generating article comprises an aerosol-generating substrate including the fire repellent reconstituted tobacco as above defined. In particular, the fire repellent reconstituted tobacco comprises 0.1 % to 10% of phosphorous groups by weight of the total weight of the fire repellent reconstituted tobacco, preferably 0.5% to 3%. The aerosol generating article also comprises a downstream section including a centre hole having an inner diameter adjacent to the downstream end of the tobacco component, an aerosol cooling section adjacent to the downstream end of the centre hole and a mouthpiece adjacent to the downstream end of the aerosol cooling section. The inner diameter of the centre hole may be ranging from 1 ,5 mm (millimetre) and 4,5 mm. The aerosol cooling section may be a paper tube or a section comprising a crimped polylactic acid sheet. Most preferably, the mouthpiece comprises a filter plug.

In another embodiment, the aerosol generating article according any of the previous described aerosol generating article may further comprise an upstream element. Such an upstream element may be arranged upstream of, and preferably adjacent to, the tobacco component (i.e. the aerosol generating substrate) of the aerosol generating article. The upstream element may be a filter plug made of cellulose acetate with or without a centre hole, a paper filter with or without a centre hole, or a combination thereof. Preferably, the upstream element is wrapped in a fire repellent cigarette paper together with the tobacco component. In some other examples, it is possible that the fire repellent cigarette paper only wraps the upstream element. In such a case, the tobacco component is wrapped by commonly used cigarette paper that does not have fireproofing property. DESCRIPTION OF DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1A shows a flowchart illustrating a first grafting process according to embodiment of the present invention;

Figure 1 B shows a flowchart illustrating a second grafting process according to the present invention;

Figure 2 shows a flowchart illustrating a method for creating a reconstituted tobacco component according to the present invention; and

Figure 3 shows a flowchart illustrating another method for creating a reconstituted tobacco component according to an embodiment of the present invention.

Figure 4 shows a flowchart illustrating a third grafting process according to the present invention.

Figure 5 shows a schematic of a heated tobacco stick with a fire repellent reconstituted tobacco component according to the present invention.

DETAILED DESCRIPTION

As used herein, the terms “bum retardant” component or “fire retardant” component or “fire repellent” component or “fireproof’ component or “fireproofing” component are used equally and refers to a component that reduce or even avoid the flammability of a material by either blocking the initiation of fire physically or by initiating a chemical reaction that stops or avoids the fire deployment. In the sense of the present invention, “bum retardant” or “fire retardant” or “fire repellent” or “fireproof’ or “fireproofing” reduce or even prohibit the combustion of tobacco material. As used herein, the term “a donor of a phosphorous group” refers to a chemical component that comprises at least one phosphorous atom available for covalent bonding to a substrate material, said substrate material being also called the receiver.

As used herein, the terms “inositol” or “myo-inositol” refer to a carbocyclic sugar and is the biologically important form of cyclohexane-1 ,2,3,4,5,6-hexol. In the context of the present invention, we specifically refer to “inositol phosphate derivative/moiety” to define an inositol component wherein at least one of the hydroxyl moieties of the inositol component is substituted with a phosphorous acid moiety. In a preferred embodiment, more than one hydroxyl moieties of the inositol component are substituted with a phosphorous acid moiety. In a most preferred embodiment, all the six hydroxyl moieties of the inositol component are substituted with a phosphorous acid moiety.

As used herein, the term “covalent bond” refers to a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows a stable electronic configuration.

Figures 1A and 1 B show schematic representations of grafting processes to fireproof tobacco fibres according to the present disclosure. The tobacco fibres in the present disclosure are ground before the grafting process

Figure 1A shows a first grafting process 100 in which ground tobacco fibres are soaked in an aqueous treatment solution comprising a donor of phosphorous groups and urea at step 105. The composition of the aqueous treatment solution includes: - 0.1 to 20 % of a donor of phosphorous groups by weight of the total weight of the treatment solution , preferably between 3 to 10 %, and

- 1 to 40 % of urea by weight of the total weight of the treatment solution, preferably between 10 to 20 %.

In particular, the donor of phosphorous group can be phytic acid (inositol hexaphosphate) or phytate as a salt, D-myo-lnositol 1 , 4, 5-triphosphate tripotassium salt, and /pr D-myo-lnositol 1 , 3, 4, 5-tetrakis(phosphate) ammonium salt.

The ratio of the ground tobacco fibres to the aqueous treatment solution is between 1 :1 to 1 :10 part material to part solution. For example, 1 gram of ground tobacco fibres to 1 ml of solution, or 1 gram of ground tobacco fibres to 10 ml of treatment solution. Preferably, the ratio is 1 gram of ground tobacco fibres to 5 ml of aqueous treatment solution. The ground tobacco fibres are soaked in the treatment solution for a time period of between 5 to 60 minutes.

Step 110 is an optional step in which the ground tobacco fibre-treatment solution mixture is filtered to remove any excess treatment solution and/or any unwanted particles from the mixture. The soaked mixture is then dried at step 115 to dry the mixture to a desired humidity level I moisture content. The drying is performed under atmospheric conditions for a period of between 5 minutes to 8 hours at a temperature of between 40 to 60 °C. The desired humidity level, or moisture content, is between 5 to 20 % as a weight percentage of the total weight of the mixture.

At step 120, the partially dried mixture is then heated at a temperature of 140 to 200 °C for a duration of 2 hours for the donor of the phosphorous groups in the aqueous treatment solution to graft onto the ground tobacco fibres.

A number of the steps in the method described above in reference to Figure 1A may be added, removed or modified to provide another fireproofing process according to the present disclosure. For example, in its simplest form, the phosphorous group may be grafted onto the tobacco fibres by only applying the treatment solution by soaking (i.e. step 105 only without any further filtering, drying or heating steps). Alternatively, a grafting process may only include the soaking step 105 and the heating step 120.

After treating the ground tobacco fibres, the treated tobacco fibres may be washed and filtered before the treated tobacco fibres are made into a fire repellent reconstituted tobacco product. Washing and filtering the treated tobacco fibres remove any excess solution and molecules. Chemically pure urea is a colourless and odourless solid that does not interfere with the colour or the mechanical properties of the final product.

Figure 1 B shows a second grafting process 150 in which the ground tobacco fibres are sprayed with the above aqueous treatment solution of a donor of phosphorous groups and urea at step 155 (instead of soaking). In particular, the donor of phosphorous group can be phytic acid (inositol hexaphosphate) or phytate as a salt, D-myo-lnositol 1 , 4, 5-triphosphate tripotassium salt, and /pr D-myo-lnositol 1 , 3, 4, 5-tetrakis(phosphate) ammonium salt.

At step 155, the ground tobacco fibres are sprayed with the aqueous treatment solution of a donor of phosphorous groups and urea to a humidity level I moisture content of 5 to 20 %. Spraying the ground tobacco fibres allows a greater control of the moisture content of the mixture, which means that the drying step 115 in the first method 100 is not necessary in the present method 150.

After spraying, the tobacco fibres are heated at step 160 in the same way as heating step 120 in the first method 100 at a temperature of 140 to 200 °C for a duration of 2 hours.

The heating step 160 is optional and may be removed or modified to provide another fireproofing process, where the phosphorous group may be grafted onto the tobacco fibres by only applying the treatment solution by spraying the treatment solution onto ground tobacco fibres. In addition, after treating the ground tobacco fibres, the treated tobacco fibres may optionally be washed and filtered before the treated tobacco fibres are made into a fire repellent reconstituted tobacco product.

Figure 2 shows a schematic representation of a method 200 to fabricate a fire repellent reconstituted tobacco component.

At step 205, tobacco leaves are first prepared by mixed with water to draw a tobacco essence from the leaves into the water. The mixture is then dehydrated at step 210 and the tobacco-essence water is extracted from the mixture and concentrated into a tobacco concentrate at step 215 for later use.

At step 220 the dehydrated tobacco leaves are then ground into micro and/or nano fibres of tobacco material by use of a mechanical dispersion mill and a homogenizer. The tobacco material may be ground in water to improve the dispersion of material and ensure optimal homogeneity of ground tobacco fibres. The tobacco material is ground into microfibres having an average diameter of between 60 to 400 pm (microns), preferably between 60 to 200 pm, and/or nanofibres having an average diameter of between 50 to 500 nm (nanometres), preferably between 50 to 100 nm. Optionally, the tobacco material, in particular tobacco stems, can also be pre-treated using steam explosion to obtain nanofibres. The nanofibres improve the mechanical properties of the reconstituted tobacco sheet (resistance and filling power) and also enhance the tobacco taste.

The tobacco material may be bleached, before or after the grinding step 220, to remove lignin from the tobacco material.

At step 225, the ground tobacco fibres are passed through a disc refiner. Disc refiners can be used to affect the structural and binding characteristics of plant tobacco fibres. In this case, the ground tobacco fibres are abraded or grated to form fibrils on its surface which will improve the binding properties of the tobacco paper mixture as well as allow the fireproofing treatment of the next step to be more effectively performed.

After the tobacco is ground into fibres, the ground tobacco fibres are then fireproofed at step 230 according to the first grafting process 100 or the second grafting process 150 described above with reference to Figures 1A or 1 B.

After the grafting process a further optional washing step may take place after heating at step 235 to further remove any excess of treatment solution comprising donors of phosphorous groups that have not reacted with the ground tobacco fibres.

The treated tobacco fibres are then made into a tobacco paper. At step 240, the treated tobacco fibre-treatment solution mixture is filtered and then worked through a paper machine. At step 245, the mixture is continuously sprayed from a headbox onto a forming wire, or forming fabric. The forming fabric is a fine- mesh fabric from which water or the excess treatment solution will be progressively sucked I removed from the overlying mixture. At the end of the forming fabric, the mixture is in the form of a tobacco sheet typically containing less than 80% water I moisture.

The sheet of treated tobacco is then transferred to the pressing or press section at step 250 by a support belt, where the press section is configured to further remove moisture from the sheet. The pressed sheet is then transferred to a rolling section at step 255 where the sheet is passed through a series of cylinders, which may be heated. At this stage, or just before step 255, the tobacco concentrate obtained at step 215 is re-applied to the pressed sheet for enhancement of the tobacco flavour of the sheet. Other flavourings may also be included at this stage.

The sheet is dried as it passes through the cylinders at step 255, and is further cut into the reconstituted tobacco product and packed at step 260 according to manufacturing requirements. Figure 3 shows a schematic representation of another method 300 to fabricate a fire repellent reconstituted tobacco component.

Instead of extracting tobacco essence / flavours from the raw material of tobacco leaves, the tobacco leaves are ground as dry leaves at step 305 into microfibres and/or nanofibres. The tobacco material is ground into microfibres having an average diameter of between 60 to 400 pm, preferably between 60 to 200 pm, and/or nanofibres having an average diameter of between 50 to 500 nanometres, preferably between 50 to 100 nm. Optionally, the tobacco material, in particular tobacco stems, can also be pre-treated using steam explosion to obtain nanofibres.

Similar to method 200, the tobacco material may be bleached, before or after the grinding step 305, to remove lignin from the tobacco material. The ground tobacco fibres may also optionally be passed through a disc refiner.

After the tobacco is ground into fibres, the ground tobacco fibres are then fireproofed at step 310 according to the first grafting process 100 or the second grafting process 150 described above with reference to Figures 1A or 1 B.

The treated tobacco fibres are then made into a slurry. At step 315, the treated tobacco fibre-treatment solution mixture is further combined I mixed into another aqueous treatment solution of water, a binder such as guar gum, pectin, and a humectant to make the slurry. In particular, the humectant is selected from the group consisting of vegetable glycerol, propylene glycol, trimethylene glycol, ethanol and a combination thereof. The slurry typically has a solid content (fibres) of 15 to 30 % wt and a binder content of 8% wt or less of the total solids content. The weight ratio of tobacco to binder is preferably between 50:1 to 10:1 .

At step 320, the slurry is de-aerated and cast into one or more tobacco sheets at step 325. The casting step 325 is typically performed at 20 to 100 °C. After casting, sheet of tobacco is dried at step 330 to ensure excess moisture has been removed, whereby the tobacco sheet(s) are further processed (e.g. cut into shape and packed) at step 335.

As will be appreciated by the skilled person, there are a few different processes that can be used to make reconstituted tobacco. The primary three processes are paper-making (described as method 200 with reference to Figure 2), slurry type (described as method 300 with reference to Figure 3) and nano-fibre type. For each process, the fireproofing I grafting process can be integrated at the very beginning of the process. It can be a batch process or a continuous process.

Figure 4 shows a schematic representation of another method 400 to fabricate a fire repellent reconstituted tobacco component.

Similar to the slurry type method 300 described with reference to Figure 3, the dry tobacco raw material, e.g. tobacco leaves, are ground at step 405 into microfibres and/or nanofibres. The tobacco material is ground into microfibres having an average diameter of between 60 to 400 pm, preferably between 60 to 200 pm, and/or nanofibres having an average diameter of between 50 to 500 nm, preferably between 50 to 100 nm. Optionally, the tobacco material, in particular tobacco stems, can also be pre-treated using steam explosion to obtain nanofibres.

Similar to methods 200, 300 described above, the tobacco material may be bleached, before or after the grinding step 405, to remove lignin from the tobacco material. The ground tobacco fibres may also optionally be passed through a disc refiner.

At step 410, after the tobacco leaves and/or steams are ground into fibres, the ground tobacco fibres are then fireproofed according to the first grafting process 100 or the second grafting process 150 described above with reference to Figures 1A or 1 B. After the grafting process, the treated tobacco fibre-treatment solution mixture is combined with another aqueous treatment solution of water, a binder such as guar gum, pectin, and a humectant at step 415. In particular, the humectant is selected from the group consisting of vegetable glycerol, propylene glycol, trimethylene glycol, ethanol and a combination thereof. The new mixture typically has a solid content (fibres) of 15 to 30 % wt and a binder content of 8% wt or less of the total solids content. The weight ratio of tobacco to binder is preferably between 50:1 to 10:1 . The new mixture undergoes an extrusion process at step 420, where the mixture is extruded into a pair of rollers. As the mixture is extruded, excess liquid (which may include the treatment solution and/or the aqueous binder solution) may be extracted or drawn out from the mixture during the extrusion process such that the extruded mixture has a predetermined moisture level I range.

At step 425, the extruded mixture passes through the pair of rollers to form a laminated sheet of reconstituted tobacco I RTB. It should be understood that as the extruded mixture passes through the rollers, further liquid may be extracted or squeezed out from the mixture as the laminated sheet is formed such that the rolled laminated sheet of reconstituted tobacco has a further predetermined moisture level I range. Optionally, the rollers may be heated or another form of drying or heating can be used to further dry laminated sheet as it is being formed. After the laminated sheet of reconstituted tobacco is formed, or even as the laminated sheet is exiting the rollers, the laminated sheet is cut into pieces of laminated RTB according to manufacturing or design requirements.

At step 430, the cuts of laminated reconstituted tobacco are further dried to ensure excess moisture has been removed, whereby the laminated cuts of reconstituted tobacco sheet can be further processed (e.g. packed or incorporated into a consumable product).

The nano-fibre reconstituted tobacco production process starts with manufacturers grinding the tobacco down and then removing sand and other nontobacco materials before preparing the tobacco sheet. Some nano-fibre-making techniques include: - Splitting of bicomponent fibres, which involves the removal of one polymer out of islands-in-the-sea (or citrus pie)-spun fibres;

- Melt-blowing, which involves drawing a polymer melt using hot air jet;

- Physical drawing, which involves physically drawing of a polymer solution;

- Flash-spinning, which involves simultaneous heating and pressurizing of polymer fluid;

- Phase separation, which involves the formation of fibres by induced phase separation of solution;

- Self-assembling, which involves self-organization of molecules in solution;

- Solvent dispersion, which involves shear-enhanced solvent precipitation in nonsolvent;

- Centrifugal spinning, which involves drawing spinning fluid using centrifugal force;

- Hydrothermal, which involves the formation of fibres in hydrothermal solution; and

- Electrospinning, which involves stretching of solution by high electric field.

The paper-making process (method 200) starts out with a similar process to some of the nano-fibre techniques, where the tobacco gets ground down and mixed with water. The grafting process then occurs right after the grinding process before it is mixed with water. The tobacco fibre materials get turned into the paper we mentioned earlier. Once the paper is laminated, they spray the water mixture over the sheets to add the components back in.

In the slurry type method (method 300), the tobacco fibre materials and soluble materials never get separated. Instead, they all get mixed into water to create a slurry. The grafting process occurs before the slurry preparation step. The slurry gets spread out and has the water evaporated out of it to create the reconstituted tobacco sheets.

In the laminated type method (method 400), the tobacco fibre materials and soluble materials do not get separated, similar to the slurry type method 300. However, instead of spreading out a slurry like in the slurry type method 300, the mixture of treated tobacco fibres and the aqueous solution of binder, pectin, humectant, etc. is extruded and then laminated into sheet(s) of reconstituted tobacco. As should be understood, excess moisture can be extracted from the mixture during the extrusion process and the rolling I lamination process. The cuts of laminated reconstituted tobacco, or RTB, are then dried to a desired moisture level.

Figure 5 shows an exemplary heated tobacco stick (HTS) 500 comprising an aerosol generating substrate 510 comprising a reconstituted tobacco component according to the present disclosure wrapped by a cigarette paper. The cigarette paper may also be a fire repellent cigarette paper. The HTS 500 further comprises a mouth end section 520 located downstream of the aerosol generating substrate 510 where generated aerosol flows toward in use. The mouth end section 520 may comprise multiple segments, including one or more of a filter plug, a central passage or hole, a support tube, and an aerosol cooling section. The mouth end 520 may comprise multiple segments, including one or more of a filter plug, a centre hole, a support tube, an aerosol cooling section, and/or a mouthpiece. The mouth end 520 is located downstream of, and preferably adjacent to, the aerosol generating substrate 510 of the aerosol generating article 500, such that in use aerosol generated from the aerosol generating substrate 510 upon application of heat, flows through the mouth end 520 to be inhaled by a user. In some examples, the mouth end 520 can comprise a cooling section, such a cooling section may be a paper tube or a section comprising a crimped polylactic acid sheet. In some other examples, the mouth end 520 can comprise a first centre hole having a first inner diameter adjacent to the downstream end of the tobacco material, a second centre hole having a second inner diameter adjacent to the downstream end of the first centre hole and a mouthpiece adjacent to the downstream end of the second centre hole. In such a case, the first inner diameter is smaller than the second inner diameter. The first inner diameter may be ranging from 1 ,5 mm (millimetre) and 4,5 mm. The second diameter may be ranging from 3,5 mm to 6,0 mm. In another example, the mouth end 520 can comprise a centre hole having an inner diameter adjacent to the downstream end of the tobacco component, an aerosol cooling section adjacent to the downstream end of the centre hole and a mouthpiece adjacent to the downstream end of the aerosol cooling section. The inner diameter of the centre hole may be ranging from 1 ,5 mm (millimetre) and 4,5 mm. The aerosol cooling section may be a paper tube or a section comprising a crimped polylactic acid sheet. The above examples should not be limiting the present invention. It will be apparent from the overall disclosure that the mouth end 520 can combine multiple segments in a different way for providing the HTS 500 and can also comprise an upstream element located upstream of, and preferably adjacent to, the tobacco component (i.e. the aerosol generating substrate 510) of the aerosol generating article 500 (not shown in Figure 5). The upstream element may be a filter plug made of cellulose acetate with or without a centre hole, a paper filter with or without a centre hole, or a combination thereof. Preferably, the upstream element is wrapped in a fire repellent cigarette paper together with the tobacco component. In some other examples, it is possible that the fire repellent cigarette paper only wraps the upstream element. In such a case, the tobacco component is wrapped by commonly used cigarette paper that does not have fireproofing property.

Claims

1. A method of manufacturing a fire repellent reconstituted tobacco component, the method comprising the steps of: grinding a tobacco material to produce ground tobacco fibres; treating the ground tobacco fibres by applying a treatment solution comprising a donor of a phosphorous group, wherein the donor of the phosphorous group comprises an inositol phosphate moiety; heating the treated tobacco fibres to obtain phosphorous-treated tobacco fibres; and processing the phosphorous-treated tobacco fibres to produce the fire repellent reconstituted tobacco component.

2. The method of claim 1 , wherein the ground tobacco fibres comprise microfibres having an average diameter less than 400 pm, and/or nanofibres having an average diameter of less than 500 nm.

3. The method of any preceding claim, wherein the treatment solution comprises 0.1 to 20% of an inositol phosphate derivative by weight of the total weight of the treatment solution, preferably 3 to 10 %.

4. The method of claim 3, wherein the inositol phosphate derivative comprises phytic acid

5. The method of claims 3 or 4, wherein the treatment solution comprises 1 to 40% urea by weight of the total weight of the treatment solution, preferably between 10 to 20%.

6. The method of any preceding claim, wherein the ratio of ground tobacco fibres to treatment solution is between 1 :1 to 1 :10, most preferably 1 :5.

7. The method of any preceding claim, wherein treating the ground tobacco fibres comprises a soaking process or a spraying process.

8. The method of claim 7, when the ground tobacco fibres are treated by soaking, wherein the treating of the ground tobacco fibres further comprises a drying step performed after the soaking process, said drying step being realised under atmospheric condition between 5 mins to 8 hrs, preferably between 15 mins to 30 mins, and at a temperature ranging from 15 °C to 60 °C, preferably ranging from 40 °C to 60 °C, and wherein a moisture content of the treated tobacco fibres after the drying step ranges between 5 and 20 % by weight of the total weight of the treated ground tobacco fibres.

9. The method of any preceding claim, wherein the treated tobacco fibres are heated at 140 to 200 °C.

10. The method of any preceding claim, prior to applying the treatment solution, the method further comprising a step of using steam explosion of the ground tobacco fibres to obtain nanofibres having an average diameter of less than 500 nm.

11 . The method of any preceding claim, the method further comprising a step of refining the ground tobacco fibres.

12. The method of any preceding claim, prior to the grinding step, the method further comprising the steps of: mixing tobacco leaves with water to form a tobacco mixture; and dehydrating the tobacco mixture to obtain a tobacco concentrate and the tobacco material for grinding, wherein the tobacco concentrate is recombined with the phosphorous-treated tobacco fibres in the processing step.

13. A fire repellent reconstituted tobacco component, the fire repellent reconstituted tobacco component comprising 0.1 % to 10 % phosphorous groups by weight of the total weight of the fire repellent reconstituted tobacco component, preferably 0.5 % to 3 %, and wherein the phosphorous groups comprise an inositol phosphate moiety.

14. The fire repellent reconstituted tobacco component of claim 13, wherein the phosphorous groups are covalently grafted to ground tobacco fibres of the reconstituted tobacco component.

15. The fire repellent reconstituted tobacco component of claims 13 or 14 comprising: ground tobacco fibres comprising microfibres having an average diameter less than 400 pm, and/or nanofibres having an average diameter of less than 500 nm.

16. An aerosol generating article for its use with a heat-not-burn aerosol generating device, the aerosol generating article comprises an aerosol-generating substrate comprising a tobacco material wrapped in cigarette paper to form a tobacco rod, said tobacco material comprises the fire repellent reconstituted tobacco component according to claim 13 to 15.