Method for producing plant-based sheet material

Abstract

The present invention relates to a method for producing a sheet of plant-based material, said method comprising:-providing a plant-based powder material and a cellulose-based sheet former,-determining the moisture content of the plant-based material,-mixing the plant-based powder material, the cellulose-based sheet former and an amount of water to form a slurry, drying the slurry to form a plant-based sheet material, wherein the amount of water added for forming the slurry is calculated based on the determined moisture content of the plant-based powder material. Such a method allows the amount of water added to form the slurry to be adjusted based on the determined moisture content of the plant-based powder material.

Description

Technical Field

[0001] The present invention relates to a method for producing a plant-based sheet. The present invention also relates to an apparatus configured for producing a plant-based sheet. Background Art

[0002] Plant-based materials such as tobacco are natural products and usually show great differences in their properties between different batches. Use these plant-based materials and sheet-forming agents such as cellulose and water to produce a slurry for producing a sheet of plant-based materials. Due to the variation in properties between different batches of plant-based materials, this mixing process is usually very difficult and time-consuming. Drying the slurry is usually very energy-consuming and time-consuming. In addition, due to the abrasive nature of the powder particles, long-term processing of plant-based materials in powder form may cause great wear and tear on the machine. Summary of the invention

[0003] It is desirable to provide a method for producing a plant-based sheet that provides an easy to handle solution. Furthermore, it is desirable to provide a method for producing a plant-based sheet that allows easy and fast drying of the slurry to produce the plant-based sheet. Furthermore, it is desirable to provide a method for producing a plant-based sheet that consumes less energy.

[0004] According to one embodiment of the present invention, a method for producing a plant-based material sheet is provided. The method may include providing a plant-based powder material and a cellulose-based sheet forming agent. The method may also include determining the moisture content of the plant-based material. The method may include mixing the plant-based powder material, the cellulose-based sheet forming agent and a certain amount of water to form a slurry. The method may also include drying the slurry to form a plant-based sheet. The amount of water added to form the slurry may be calculated based on the determined moisture content of the plant-based powder material.

[0005] Another embodiment of the present invention provides a method for producing a plant-based material sheet. The method includes providing a plant-based powder material and a cellulose-based sheet forming agent. The method also includes determining the moisture content of the plant-based material. The method includes mixing the plant-based powder material, the cellulose-based sheet forming agent, and a certain amount of water to form a slurry. The method also includes drying the slurry to form a plant-based sheet. The amount of water added to form the slurry is calculated based on the determined moisture content of the plant-based powder material.

[0006] Such a method may provide a simpler way to dry the slurry to form the plant-based sheet. This may be due to the slurry having a more uniform moisture content taking into account the moisture content of the plant-based powder material. The method may produce a slurry having a more uniform moisture content in different batches of plant-based powder material having different moisture contents. This may simplify the handling of the slurry during the production of the plant-based material sheet. This may reduce the processing time in the machine during the drying of the slurry. This may reduce the wear and tear of the machine.

[0007] The moisture content of the plant-based powder material may in particular be the water content of the plant-based powder material. This moisture content may vary between different batches of plant-based powder material. This different moisture content may hinder a more uniform treatment of the plant-based powder material during the manufacture of the plant-based material sheet. The method of the present invention may allow these different moisture contents of different batches to be taken into account when producing a slurry with a more uniform moisture content.

[0008] The slurry may have a predetermined target moisture content range. The amount of water added to form the slurry may be calculated so that the slurry reaches a moisture content within the predetermined target moisture content range.

[0009] This can allow different batches of slurry to be within the same predetermined target moisture content range despite the plant-based materials having different moisture contents. This can facilitate more uniform processing and drying of the slurry to form the plant-based sheet.

[0010] Based on the total weight of the slurry, the predetermined target water content of the slurry may range from 55 wt% to 85 wt% water. Preferably, based on the total weight of the slurry, the target water content of the slurry may range from 60 wt% to 80 wt% water.

[0011] Such a predetermined target moisture content range may be easily achieved considering the moisture content of the plant-based powder material.Such a predetermined target moisture content range of the slurry may allow for more uniform and easy drying of the slurry to form a plant-based sheet.

[0012] A predetermined target moisture content between 55 wt % and 85 wt % can reduce the occurrence of defects in the plant-based sheet, which may occur if the moisture content is below the lower limit of 55 wt %. Similarly, a moisture content outside this predetermined target moisture content may result in a decrease in the tensile strength of the plant-based sheet and may complicate the handling of the plant-based sheet.

[0013] A plant material moisture detector may be used to determine the moisture content of plant-based materials.

[0014] The plant-based powder material may be dispersed on a conveyor belt. The radiation emitted from the plant material moisture detector may be located on one side of the conveyor belt, and the radiation receiver of the plant material moisture detector may be located on the opposite side of the conveyor belt. This may allow the radiation of the plant material moisture detector to pass through the plant-based powder material.

[0015] This may allow the plant-based powder material to be transported on a conveyor belt while the moisture content of the plant-based material is determined.

[0016] The plant material moisture detector may be one of a microwave detector or an infrared detector. Preferably, the plant material moisture detector may be a microwave detector.

[0017] The microwave detector may include a transmitting antenna and a receiving antenna. The transmitting antenna may transmit microwave radiation, and the receiving antenna may receive the microwave radiation sent from the transmitting antenna through the plant-based powder. The plant-based powder material may be arranged between the transmitting antenna and the receiving antenna of the microwave detector and may be transported on a conveyor belt.

[0018] This may allow the plant-based powder material to be conveyed to form a slurry. This may allow the moisture content of the plant-based powder material to be easily determined while the plant-based powder material is being conveyed on a conveyor belt.

[0019] The microwave detector may be a microwave detector sold by Berthold Technologies GmbH & Co. KG as MicroPolar LB 567 / LB 568 Microwave Moisture Analyzer.

[0020] Preferably, the plant-based powder material may comprise tobacco powder.The plant-based powder material may be tobacco powder and the sheet of material may be a sheet of an aerosol-forming substrate.

[0021] As used herein, the term "aerosol-forming substrate" relates to a substrate capable of releasing one or more volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may suitably be part of an aerosol-generating article or a smoking article.

[0022] Aerosol formation substrate can comprise solid aerosol formation substrate.Aerosol formation substrate can comprise both solid component and liquid component.Aerosol formation substrate can comprise tobacco-containing material, and described tobacco-containing material contains volatile tobacco flavor compounds released from substrate when heating.Aerosol formation substrate can comprise non-tobacco material.Aerosol formation substrate can comprise aerosol forming agent that contributes to dense and stable aerosol formation.The example of suitable aerosol forming agent is glycerine and propylene glycol.

[0023] Aerosol formation substrate can be solid aerosol formation substrate, in some embodiments, solid aerosol formation substrate can comprise one or more of the following: powder, granule, pellet, fragment, thin strip, strip or sheet, it contains one or more of the following: herbaceous plant leaf, tobacco leaf, the fragment of tobacco leaf rib, reconstituted tobacco, homogenized tobacco, extruded tobacco, cast leaf tobacco and expanded tobacco.Solid aerosol formation substrate can be in loose form, or can be provided in suitable container or tube.Alternatively, solid aerosol formation substrate can contain the extra tobacco or non-tobacco volatile aroma compounds released when substrate is heated.Solid aerosol formation substrate can also contain capsule, and described capsule for example comprises extra tobacco or non-tobacco volatile aroma compounds, and such capsule can melt during the heating period of solid aerosol formation substrate.

[0024] As used herein, homogenized tobacco refers to the material formed by agglomerating particle tobacco.Homogenized tobacco can be in the form of sheet.The homogenized tobacco material can have an aerosol forming agent with a dry weight content greater than 5%.Alternately, the homogenized tobacco material can have an aerosol forming agent with a dry weight content between 5 weight % and 30 weight %.The sheet of homogenized tobacco material can be formed by agglomerating particle tobacco, and the particle tobacco can be obtained by grinding one or both of tobacco leaf blade and tobacco leaf stem or otherwise combining.Alternately or in addition, the sheet of homogenized tobacco material can include one or more of tobacco dust, cigarette dust and other particle tobacco byproducts formed during, for example, disposal, processing and transportation of tobacco. The sheet of homogenized tobacco material may include one or more intrinsic binders as tobacco endogenous binders, one or more non-intrinsic binders as tobacco exogenous binders, or a combination thereof to help particulate tobacco agglomerate; alternatively or in addition, the sheet of homogenized tobacco material may include other additives, including but not limited to tobacco and non-tobacco fibers, aerosol formers, humectants, plasticizers, flavorings, fillers, aqueous solvents and non-aqueous solvents, and combinations thereof.

[0025] In a particularly preferred embodiment, the aerosol-forming substrate comprises the gathered curled sheet of homogenized tobacco material. As used herein, the term "curled sheet" means a sheet with a plurality of substantially parallel ridges or folds. Preferably, when the aerosol-generating article has been assembled, the substantially parallel ridges or folds extend along or parallel to the longitudinal axis of the aerosol-generating article. This advantageously promotes the gathering of the curled sheet of homogenized tobacco material to form an aerosol-forming substrate. However, it should be understood that the curled sheet of the homogenized tobacco material included in the aerosol-generating article can alternatively or additionally have a plurality of substantially parallel ridges or folds that are arranged at an acute angle or an obtuse angle with the longitudinal axis of the aerosol-generating article when the aerosol-generating article has been assembled. In certain embodiments, the aerosol-forming substrate can comprise the gathered sheet of homogenized tobacco material, and the gathered sheet is substantially uniformly textured on substantially its entire surface. For example, the aerosol-forming substrate may comprise a gathered crimped sheet of homogenised tobacco material comprising a plurality of substantially parallel ridges or corrugations that are substantially evenly spaced across the width of the sheet.

[0026] The aerosol-forming substrate may be used in an aerosol-generating article. The aerosol-generating article may be used with an aerosol-generating device. The aerosol-generating device may include a cavity configured to receive the aerosol-generating article. The aerosol-generating device may include a heating element configured to heat the aerosol-generating article received in the cavity. The aerosol-generating device of the present invention may be configured to heat the aerosol-forming substrate to a temperature that is below the combustion temperature of the aerosol-forming substrate but at or above the temperature at which one or more volatile compounds of the aerosol-forming substrate are released to form an inhalable aerosol.

[0027] Plant-based powder material, preferably tobacco powder, can have the average particle size between 20 microns and 200 microns, preferably the average particle size between 50 microns and 100 microns.The average particle size can be determined by laser scattering.The average particle size of plant-based powder material can be adjusted to a predetermined average particle size range by grinding in a mill.The average particle size of plant-based powder material can be adjusted before forming a slurry.

[0028] This can simplify the formation of the slurry. This can provide a more homogeneous slurry.

[0029] The average particle size of the plant-based powder material may be determined before the moisture content of the plant-based material is determined. The average particle size of the plant-based powder material may affect the moisture content of the plant-based powder material. Therefore, the average particle size of the plant-based powder material may be adjusted to a predetermined average particle size range between 20 microns and 200 microns before the moisture content is determined.

[0030] When determining the average particle size of the plant-based powder material, a particle size sensor may be employed. The particle size sensor may be a laser scattering particle size distribution analyzer, such as a Horiba LA-950.

[0031] A water flow rate controller may be employed. The flow rate controller may control the amount of water added to form the slurry based on the determined moisture content of the plant-based powder material.

[0032] This can provide a simple way of controlling the amount of water added to form the slurry.

[0033] An open loop control system may be employed. The open loop control system may adjust the pump speed of the flow rate controller based on the determined moisture content of the plant-based powder material. This may allow the flow rate controller to control the amount of water added to form the slurry.

[0034] The cellulose-based sheet forming agent may include cellulose fibers. Preferably, a water / cellulose fiber pulp is prepared and then the pulp is mixed with a plant-based powder material. The water / cellulose pulp may include cellulose fibers with an average length between 0.2 mm and 4 mm. Preferably, the average length of the cellulose fibers may be between 1 mm and about 3 mm. Preferably, the cellulose fibers are softwood fibers.

[0035] Before being added to the slurry, the water-cellulose fiber pulp may have a cellulose fiber concentration between 3 wt% and 5 wt% of the total weight of the pulp. After the pulp is mixed with water and the plant-based powder material, the total amount of cellulose fibers in the slurry is between 1 wt% and 3 wt%, preferably between 1.2 wt% and 2.4 wt% of the dry weight of the slurry.

[0036] The slurry may be dried to form a plant-based sheet, wherein the plant-based sheet has a moisture content of between 7% and 15% of the dry weight of the sheet. Preferably, the plant-based sheet may be dried to have a moisture content of between 8% and 12% of the dry weight of the sheet.

[0037] Can prepare slurry in slurry tank. Subsequently, slurry can be transferred to casting box. This can allow casting slurry by the casting knife on movable conveyor belt. Conveyor belt can be made of heat-conducting material, particularly made of steel. After drying, can form continuous plant-based material sheet with thickness between 500 microns and 700 microns. If plant-based powder material comprises tobacco powder, then plant-based material sheet can be continuous sheet of tobacco cast leaf. These tobacco cast leaf materials can be wound into tube and can be further processed to produce aerosol generation products comprising tobacco cast leaf material as a part of aerosol formation substrate.

[0038] It is also possible to form a sheet of a gel-like material comprising tobacco, rather than forming a tobacco cast sheet.

[0039] The slurry arranged on the conveyor belt can be dried by subjecting it to dry air in the drying device. In addition, steam can be provided from below the conveyor belt to dry the plant-based material sheet in a more uniform manner. The slurry can be transported through the drying device on the conveyor belt. The temperature of the dry air can be between 90 degrees Celsius and 140 degrees Celsius. In one embodiment, the drying device may include different drying sections. The temperature of the dry air, the flow rate of the dry air, and the flow rate distribution of the dry air can be independently controlled in different drying sections of the drying device. The flow rate of the dry air in the drying device can be between 80 kg / hour and 300 kg / hour. The length of the drying device can be several hundred meters.

[0040] This can allow for a prolonged drying process of the slurry as it passes through the drying device on a conveyor belt. This can allow for a slow and controlled reduction of moisture, thereby producing a plant-based sheet.

[0041] This may allow the moisture of the slurry to be reduced in a controlled manner without subjecting the plant-based material sheet formed from the slurry to excessively high temperatures or moisture differentials.

[0042] One or both of a thickener and an aerosol former may be added to form a slurry. The thickener may include guar gum. The aerosol former is any suitable known compound or mixture of compounds that promotes the formation of a dense and stable aerosol in use and is substantially resistant to thermal degradation at the operating temperature of the system. Suitable aerosol formers are well known in the art and include, but are not limited to: polyols such as triethylene glycol, 1,3-butylene glycol and glycerol; esters of polyols such as glycerol monoacetate, glycerol diacetate or glycerol triacetate; and aliphatic esters of monocarboxylic acids, dicarboxylic acids or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. The aerosol former may be a polyol or a mixture thereof, such as triethylene glycol, 1,3-butylene glycol and glycerol. The aerosol former may be propylene glycol. The aerosol former may include both glycerol and propylene glycol. Preferably, the aerosol former may include one or more of triethylene glycol, 1,3-butylene glycol and glycerol.

[0043] An exemplary slurry composition can include water between 70% and 78% by weight, plant-based powders between 17% and 22% by weight, particularly tobacco powder. This exemplary slurry composition can also include glycerine between 3% and 6% by weight as an aerosol forming agent. Cellulose fiber can be added in an amount of 0.5% to 4% by weight. Optional thickeners can exist in an amount of 0% to 1% by weight. All weight percentage ranges indicated are based on the gross weight of the exemplary slurry composition.

[0044] The slurry may have a predetermined target moisture content range. The sum of the determined moisture content of the plant-based powder material and the amount of water added to form the slurry may result in a moisture content of the slurry within the target moisture content range.

[0045] Another embodiment of the method of the present invention may further include a method step of determining the moisture content of the cellulose-based sheet forming agent. In this case, the sum of the determined moisture content of the plant-based powder material, the amount of water added to form the slurry, and the moisture content of the cellulose-based sheet forming agent may result in a slurry having a moisture content within a target moisture content range.

[0046] This embodiment of the method of the present invention can take into account not only the moisture content of the plant-based powder material but also the moisture content of the cellulose-based sheet-forming agent when determining the total amount of water to be added to form the slurry. This can provide a method that can more accurately adjust the water to be added to be within a predetermined target moisture content range.

[0047] In another embodiment of the method of the present invention, the moisture content of one or both of the thickener and the aerosol forming agent may be determined. In this case, the determined moisture content of the plant-based powder material, the amount of water added to form the slurry, the moisture content of the cellulose-based sheet forming agent, and the moisture content of one or both of the thickener and the aerosol forming agent may result in a final slurry having a moisture content within a target moisture content range.

[0048] In this embodiment of the method of the present invention, the moisture content of the aerosol former, thickener and cellulose-based sheet former may also be determined and may be considered together with the moisture content of the plant-based powder material when calculating the amount of water to be added to form the slurry.

[0049] This may provide a method of more accurately adjusting the final moisture content of the slurry to be formed.

[0050] The moisture content of the cellulose-based sheet former, aerosol former and thickener can be determined in the same manner as the moisture content of the plant-based powder material. In particular, a cellulose moisture detector such as a microwave detector or an infrared detector can be used to determine the moisture content of the cellulose-based sheet former.

[0051] In particular, a cellulose fiber feed and preparation line can be used to prepare the above-mentioned water / cellulose pulp. The cellulose fiber feed and preparation line may include a cellulose conveyor belt for conveying raw cellulose fiber materials such as boards, sheets or loose fibers to a pulper to prepare water / cellulose pulp. A cellulose moisture detector may be present on the cellulose conveyor belt. The cellulose moisture detector may be configured to determine the moisture content of the raw cellulose fiber materials. The cellulose fiber feed and preparation line may also include a water line configured to introduce water into the pulper. The flow rate of water through the water line may be controlled by a cellulose flow rate controller. The cellulose flow rate controller may be configured to receive data about the moisture content of the raw cellulose fiber materials from the cellulose moisture detector. The cellulose flow rate controller may adjust the speed of the pump in consideration of the moisture content of the raw cellulose fiber materials and the moisture content of the plant-based powder material to prepare the water / cellulose pulp. Then, the water / cellulose pulp may be mixed with the plant-based powder material to prepare the final slurry. Therefore, the moisture content of the water / cellulose pulp will also affect the final moisture content of the slurry to be prepared.

[0052] The step of mixing water and cellulose fibers may last between 20 minutes and 60 minutes. The temperature in the pulper may be between 15 degrees Celsius and 40 degrees Celsius. The storage time of the water / cellulose pulp before mixing with the plant-based powder material may be between 0.1 days and 7 days.

[0053] Preferably, the water / cellulose pulp may be mixed with additional water prior to mixing with the plant-based powder material. This mixing step of the water / cellulose pulp with additional water may last between about 120 minutes and 180 minutes. The temperature during mixing may be between 15 degrees Celsius and 40 degrees Celsius, more preferably between 18 degrees Celsius and 25 degrees Celsius.

[0054] The weight percentage of water, particularly the final water content range of the slurry comprising the plant-based powder material, the cellulose-based sheet forming agent, the thickener and the aerosol forming agent, can be calculated as follows:

[0055] The weight percentage of water in the slurry = [amount of water added to the slurry + water content of cellulose + water content of aerosol former + water content of thickener + water content of plant-based powder material] / [(amount of thickener + water content of thickener) + (amount of aerosol former + water content of aerosol former) + (amount of plant-based material + water content of plant-based material) + amount of water added to the slurry].

[0056] Another embodiment of the present invention provides an apparatus configured to produce plant-based material sheets. The apparatus may include a mixing tank including an agitator. The mixing tank may be configured to mix plant-based powder material and a cellulose-based sheet forming agent to form a slurry. The apparatus may include a plant material moisture detector configured to determine the moisture content of the plant-based powder material. The apparatus may also include a water flow rate controller. The water flow rate controller may be configured to control the flow rate of water to the mixing tank. The water flow rate controller may be connected to a water pipe. The water pipe may be configured to transport water to a slurry container to form a slurry. The water flow rate controller may also be configured to provide a certain amount of water to the mixing tank to form a slurry. The amount of water may be calculated based on the determined moisture content of the plant-based powder material. The apparatus may include a drying device for drying the slurry to form a plant-based sheet.

[0057] Yet another embodiment of the present invention provides an apparatus configured for producing plant-based material sheets. The apparatus includes a mixing tank including an agitator. The mixing tank is configured to mix a plant-based powder material and a cellulose-based sheet forming agent to form a slurry. The apparatus also includes a plant material moisture detector. The plant material moisture detector is configured to determine the moisture content of the plant-based powder material. The apparatus also includes a water flow rate controller. The water flow rate controller is configured to provide water to the mixing tank. The water flow rate controller is also configured to provide a certain amount of water to the mixing tank to form a slurry, wherein the amount of water is calculated based on the determined moisture content of the plant-based powder material. The apparatus also includes a drying device for drying the slurry to form a plant-based sheet.

[0058] Such an apparatus may be configured to carry out a method for forming a sheet of plant-based material as discussed herein.The apparatus may readily be capable of controlling the amount of water added to form the slurry via a water flow rate controller.

[0059] The apparatus may further include an open loop control system. The open loop control system may be configured to adjust a pump speed of the flow rate controller based on the determined moisture content of the plant-based powder material.

[0060] The apparatus may include a data processing unit. The data processing unit may include a module for communicating with a plant material moisture detector. The data processing unit may include a module for calculating an amount of water to be added to form a slurry based on the determined moisture content of the plant-based material. The data processing unit may include at least a portion of a control system.

[0061] This may simplify the addition of an appropriate amount of water to form a slurry based on the determined moisture content of the plant-based powder material.

[0062] The slurry may have a predetermined target moisture content range. The open loop control system may be configured to provide an amount of water to the mixing tank such that the sum of the determined moisture content of the plant-based powder material and the amount of water added to form the slurry results in a moisture content of the slurry within the target water range.

[0063] Such an apparatus may be readily capable of taking into account the determined moisture content of the plant-based powder material when calculating the amount of water to be added to form the slurry, such that the moisture content of the slurry is within a target moisture content range.

[0064] The apparatus may further include a cellulose moisture detector configured to determine the moisture content of the cellulose-based sheet forming agent. The open loop control system of the apparatus may then be configured to provide such an amount of water to the mixing tank that the sum of the determined moisture content of the plant-based powder material, the determined moisture content of the cellulose-based sheet forming agent and the amount of water added to form the slurry results in a moisture content of the slurry within a target moisture content range.

[0065] The apparatus may also take into account the moisture content of the cellulose-based sheet forming agent when calculating the amount of water to be added to form the slurry.

[0066] The apparatus may further include one or both of a thickener moisture detector and an aerosol former moisture detector configured to determine the moisture content of one or both of the thickener and the aerosol former.

[0067] The open-loop control system of the apparatus may then be configured to provide such an amount of water to the mixing tank that the sum of the determined moisture content of the plant-based powder material, the determined moisture content of the cellulose-based sheet forming agent, one or both of the moisture contents of the thickener and the aerosol forming agent, and the amount of water added to form the slurry results in a moisture content of the slurry within a target moisture content range.

[0068] Such an apparatus may be configured to take into account the moisture content of all major components of the slurry when calculating the amount of water to be added to form the slurry.

[0069] A non-exhaustive list of non-limiting examples is provided below.Any one or more features of these examples may be combined with any one or more features of another example, embodiment or aspect described herein.

[0070] Example E1: A method for producing a sheet of plant-based material, the method comprising:

[0071] - providing a plant-based powder material and a cellulose-based sheet-forming agent,

[0072] - Determine the moisture content of plant-based materials,

[0073] - mixing the plant-based powder material, the cellulose-based sheet-forming agent and a certain amount of water to form a slurry,

[0074] - drying the slurry to form a plant-based sheet,

[0075] - wherein the amount of water added to form the slurry is calculated based on the determined moisture content of the plant-based powder material.

[0076] Example E2: The method of Example E1, wherein the slurry has a predetermined target moisture content range, and wherein the amount of water added to form the slurry is calculated so that the slurry reaches a moisture content within the predetermined target moisture content range.

[0077] Example E3: The method according to any of the preceding examples, wherein a plant material moisture detector is used to determine the moisture content of the plant-based material, preferably wherein the plant material moisture detector is one of a microwave detector or an infrared detector.

[0078] Example E4: A method according to the previous example, wherein the plant-based powder material is dispersed on a conveyor belt, and wherein the radiation emitter of the plant material moisture detector is located on one side of the conveyor belt and the radiation receiver of the plant material moisture detector is located on the opposite side of the conveyor belt so that the radiation of the plant material moisture detector passes through the plant-based powder material.

[0079] Example E5: The method according to any of the preceding examples, wherein the plant-based powder material comprises tobacco powder, preferably wherein the plant-based powder material is tobacco powder and wherein the sheet of material is a sheet of an aerosol-forming substrate.

[0080] Example E6: The method according to any of the preceding examples, wherein the plant-based powder material is adjusted to a particle size between 20 μm and 200 μm, preferably to a particle size of 50 μm to 100 μm, before forming the slurry.

[0081] Example E7: The method according to any of the preceding examples, wherein the particle size of the plant-based powder material is determined, preferably wherein the particle size of the plant-based material is determined before determining the moisture content of the plant-based material.

[0082] Example E8: The method of any of the preceding examples, wherein a water flow rate controller is employed, wherein the flow rate controller controls the amount of water added to form the slurry based on the determined moisture content of the plant-based powder material.

[0083] Example E9: The method of the preceding example, wherein an open loop control system is employed that adjusts a pump speed of the flow rate controller based on the determined moisture content of the plant-based powder material.

[0084] Example E10: A method according to any of the preceding examples, wherein the cellulose-based sheet forming agent comprises cellulose fibers, preferably wherein a water / cellulose fiber pulp is prepared and mixed with a plant-based powder material, more preferably wherein the water / cellulose fiber pulp comprises cellulose fibers having an average length between 0.2 mm and 4 mm, more preferably between 1 mm and about 3 mm.

[0085] Example E11: A method according to any of the preceding claims, wherein the predetermined target moisture content of the slurry ranges from 55 wt% to 85 wt% water, based on the total weight of the slurry, preferably wherein the target moisture content of the slurry ranges from 60 wt% to 80 wt% water.

[0086] Example E12: A method according to any of the preceding examples, wherein the slurry is dried to form a plant-based sheet, wherein the plant-based sheet has a moisture content between 7% and 15% of the dry weight of the sheet, preferably wherein the plant-based sheet has a moisture content between 8% and 12% of the dry weight of the sheet.

[0087] Example E13: The method according to any of the preceding examples, wherein one or both of a thickener and an aerosol former are added to form a slurry, preferably wherein the thickener comprises guar gum and wherein the aerosol former comprises one or more of triethylene glycol, 1,3-butanediol and glycerol.

[0088] Example E14: The method of any of the preceding examples, wherein the slurry has a predetermined target moisture content range, and wherein the sum of the determined moisture content of the plant-based powder material and the amount of water added to form the slurry results in a moisture content of the slurry within the target moisture content range.

[0089] Example E15: A method according to the previous example, wherein the moisture content of the cellulose-based sheet forming agent is determined, and wherein the sum of the determined moisture content of the plant-based powder material, the amount of water added to form the slurry and the moisture content of the cellulose-based sheet forming agent results in a moisture content of the slurry within a target moisture content range.

[0090] Example E16: According to the method of the previous example, also subordinate to Example E13, wherein the moisture content of one or both of the thickener and the aerosol former is determined, and wherein the sum of the determined moisture content of the plant-based powder material, the amount of water added to form the slurry, the cellulose-based sheet forming agent and the moisture content of one or both of the thickener and the aerosol former results in the moisture content of the slurry being within the target moisture content range.

[0091] Example E17: An apparatus configured to produce a sheet of plant-based material, the apparatus comprising

[0092] - a mixing tank comprising an agitator, the mixing tank being configured to mix the plant-based powder material and the cellulose-based sheet forming agent to form a slurry,

[0093] - a plant material moisture detector configured to determine the moisture content of a plant-based powder material,

[0094] - a water flow rate controller configured to provide water to the mixing tank, wherein the water flow rate controller is further configured to provide an amount of water to the mixing tank to form a slurry, wherein the amount of water is calculated based on the determined moisture content of the plant-based powder material, and

[0095] - Drying means for drying the slurry to form the plant-based sheet.

[0096] Example E18: The apparatus of the preceding example, comprising an open loop control system configured to adjust a pump speed of the flow rate controller based on the determined moisture content of the plant-based powder material.

[0097] Example E19: Apparatus according to the preceding example, wherein the slurry has a predetermined target moisture content range and wherein the open-loop control system is configured to provide an amount of water to the mixing tank such that the sum of the determined moisture content of the plant-based powder material and the amount of water added to form the slurry results in a moisture content of the slurry within the target moisture content range.

[0098] Features described with respect to one embodiment may be equally applicable to other embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] The present invention will be further described, by way of example only, with reference to the accompanying drawings, in which:

[0100] Figure 1 A schematic diagram showing one embodiment of an apparatus for producing a sheet of plant-based material, the apparatus including a plant material moisture detector;

[0101] Figure 2 A more detailed schematic diagram of a radiation emitter and a radiation receiver of a plant material moisture detector is depicted relative to a plant-based powder material whose moisture content is to be determined. DETAILED DESCRIPTION

[0102] In the following, elements having the same function are provided with the same reference numerals in all the figures.

[0103] Figure 1 A schematic diagram of one embodiment of an apparatus 30 for producing a sheet of plant-based material is shown. Preferably, the apparatus 30 is configured for producing a sheet of tobacco-based material for forming an aerosol-forming substrate.

[0104] The apparatus 30 includes a conveyor belt 14 for conveying the plant-based powder material 10 to the plant-based powder material hopper 15. There is a plant material moisture detector 12. The plant material moisture detector 12 is configured to determine the moisture content of the plant-based powder material. The plant material moisture detector 12 is connected to a flow rate controller 26. The flow rate controller 26 can determine the amount of water to be added to form a slurry based on the determined moisture content of the plant-based powder material. The flow rate controller 26 can control the water inlet 20 to control the total amount of water added to form the slurry. The water inlet 20 is part of a first delivery line 20A for water to be added to form a slurry and for delivering a cellulose-based sheet forming agent. There is a second delivery line 22A controlled by a separate water inlet 22. The second delivery line 22A delivers a thickener such as guar gum and an aerosol forming agent to a mixer 18 to form a slurry. The plant-based powder material hopper 15 delivers the plant-based powder material to a silo 16A via a first conveyor belt 17A for storage. The plant-based powder material is then further conveyed by a second conveyor belt 17B to a mixer 16B, which ultimately conveys the plant-based powder material to a slurry mixer 18. The mixer 16B can receive the plant-based powder material and a certain amount of water to produce a mixture of the plant-based powder material and water. The mixture can then be added to the slurry mixer 18. In the slurry mixer 18, the plant-based powder material is mixed with the amount of water, the cellulose-based sheet forming agent, the thickener, and the aerosol forming agent determined by the flow rate controller to form a slurry. Such an apparatus allows the water flow rate of the water to be added to form the slurry to be adjusted based on the calculated moisture content of the plant-based material determined via the plant material moisture detector 12.

[0105] Figure 2A schematic diagram of a plant material moisture detector 12 having a radiation transmitter 12A and a radiation receiver 12B is depicted. The microwave radiation indicated by the dotted line is emitted by the radiation transmitter 12A of the plant material moisture detector 12. This emitted microwave radiation passes through the plant-based powder material 10 located on the conveyor belt 14 and is received by the radiation receiver 12B. This microwave radiation passing through the plant-based powder material can be used to calculate the moisture content of the plant-based powder material. The moisture in the plant-based powder material will cause the attenuation and phase shift of the microwave radiation passing through the material. The comparison of the microwave radiation received by the radiation receiver and the microwave radiation emitted by the radiation transmitter allows the determination of the overall attenuation and phase shift of the microwave radiation due to the interaction of the microwave radiation with the plant-based powder material and the moisture content of the material. The flow rate controller 26 includes a module 26A for calculating the moisture content and a module 26B for communicating between the data processing unit and the plant material moisture detector 12. The communication module 26B can communicate with a modem 32 for communication. The modem 32 can also communicate with a data processing unit 34. The data processing unit is also configured to control equipment configured for producing sheets of plant-based material. There may be a conveyor belt compensation device 36 that is capable of generating a compensation signal due to any accidental absorption of microwaves by the material of the conveyor belt. The compensation device can provide a compensation signal in the range of 4 mA to 20 mA. The arrow represented by "1" shows the communication line for amplitude attenuation. The arrow represented by "2" shows the communication line for phase shift. These two communication lines provide further information about amplitude attenuation and phase shift, which are caused only by the plant-based powder material and not by the moisture content of the material. This allows module 26A to calculate the moisture content to correctly determine the amplitude attenuation and phase shift of the microwave radiation caused only by moisture and not by the plant-based material itself. This allows the moisture content of the plant-based powder material to be accurately determined.

Claims

1. A method for producing a plant-based material sheet, the method comprising: - providing a plant-based powder material and a cellulose-based sheet-forming agent, - Determine the moisture content of plant-based materials, - mixing the plant-based powder material, the cellulose-based sheet-forming agent and a certain amount of water to form a slurry, - drying the slurry to form a plant-based sheet, - wherein the amount of water added to form the slurry is calculated based on the determined moisture content of said plant-based powder material.

2. The method of claim 1, wherein the slurry has a predetermined target moisture content range, and wherein the amount of water added to form the slurry is calculated so that the slurry reaches a moisture content within the predetermined target moisture content range.

3. A method according to any one of the preceding claims, wherein a plant material moisture detector is used to determine the moisture content of the plant-based material, preferably wherein the plant material moisture detector is one of a microwave detector or an infrared detector.

4. A method according to the preceding claim, wherein the plant-based powder material is dispersed on a conveyor belt, and wherein the radiation emitter of the plant material moisture detector is located on one side of the conveyor belt and the radiation receiver of the plant material moisture detector is located on the opposite side of the conveyor belt so that the radiation of the plant material moisture detector passes through the plant-based powder material.

5. A method according to any one of the preceding claims, wherein the plant-based powder material comprises tobacco powder, preferably wherein the plant-based powder material is tobacco powder and wherein the sheet of material is a sheet of an aerosol-forming substrate.

6. The method according to any one of the preceding claims, wherein the plant-based powder material is adjusted to a particle size between 20 μm and 200 μm, preferably to a particle size between 50 μm and 100 μm, before forming the slurry.

7. The method according to any one of the preceding claims, wherein the particle size of the plant based powder material is determined, preferably wherein the particle size of the plant based material is determined before determining the moisture content of the plant based material.

8. The method according to any one of the preceding claims, wherein a water flow rate controller is employed, wherein the flow rate controller controls the amount of water added to form the slurry based on the determined moisture content of the plant-based powder material.

9. A method according to any one of the preceding claims, wherein the cellulose-based sheet forming agent comprises cellulose fibres, preferably wherein a water / cellulose fibre pulp is prepared and mixed with the plant-based powder material, more preferably wherein the water / cellulose fibre pulp comprises cellulose fibres having an average length between 0.2 mm and 4 mm, more preferably between 1 mm and about 3 mm.

10. The method according to any one of the preceding claims, wherein the predetermined target moisture content of the slurry ranges from 55 wt% to 85 wt% water, based on the total weight of the slurry, preferably wherein the target moisture content of the slurry ranges from 60 wt% to 80 wt% water.

11. A method according to any one of the preceding claims, wherein the slurry is dried to form the plant-based sheet, wherein the plant-based sheet has a moisture content between 7% and 15% of the dry weight of the sheet, preferably wherein the plant-based sheet has a moisture content between 8% and 12% of the dry weight of the sheet.

12. The method of any one of the preceding claims, wherein the slurry has a predetermined target moisture content range, and wherein the sum of the determined moisture content of the plant-based powder material and the amount of water added to form the slurry results in a moisture content of the slurry within the target moisture content range.

13. The method according to the preceding claim, wherein the moisture content of the cellulose-based sheet forming agent is determined, and wherein the sum of the determined moisture content of the plant-based powder material, the amount of water added to form the slurry and the moisture content of the cellulose-based sheet forming agent results in a moisture content of the slurry within the target moisture content range.

14. An apparatus configured for producing a sheet of plant-based material, the apparatus comprising - a mixing tank comprising an agitator, the mixing tank being configured to mix the plant-based powder material and the cellulose-based sheet-forming agent to form a slurry, - a plant material moisture detector configured to determine the moisture content of said plant-based powder material, - a water flow rate controller configured to provide water to the mixing tank, wherein the water flow rate controller is further configured to provide an amount of water to the mixing tank to form a slurry, wherein the amount of water is calculated based on the determined moisture content of the plant-based powder material, and - Drying means for drying said slurry to form a plant-based sheet.

15. Apparatus according to the preceding claim, comprising an open loop control system configured for adjusting the pump speed of the flow rate controller based on the determined moisture content of the plant-based powder material.

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