Method for determining the content of additives in tobacco paper for electronic cigarettes

Abstract

The invention relates to a method for determining the additive content (vol-% or wt-%) in a tobacco paper for an electronic cigarette, which is produced from a pulp-like mass of additives, water, aroma substances and tobacco, wherein the pulp-like mass is dried into a single-layered tobacco paper, wherein the tobacco paper is measured in at least one microwave resonator, which has two resonance modes with two resonance frequencies, the smaller of the two resonance frequencies being in a frequency range of less than 1 GHz and the larger of the two resonance frequencies being in a microwave range of more than 2 GHz, for each of the two resonance modes a density-independent moisture value is calculated and from the two density-independent moisture values the additive content is determined.

Description

Technical Field

[0001] This invention relates to a method for determining the content of additives in tobacco paper used in electronic cigarettes. Background Technology

[0002] Glycerin (E422) is an additive used as a humectant in tobacco products. In cigarette tobacco (Zigarettentabak) and pipe tobacco (Pfeifentabak), the humectant primarily serves to extend the product's shelf life and prevent it from drying out. In hookah tobacco (Shisha-Tabak), a large amount of humectant is mixed into the tobacco to both prevent combustion and produce the densest possible vapor. Additionally, glycerin is used in e-cigarettes, where it forms a dense, white vapor when heated.

[0003] In manufacturing a specific type of electronic cigarette, glycerin, binders, flavorings, tobacco, and other aerosol-forming additives are mixed into a slurry. This slurry is rolled and dried, thereby producing what is known as tobacco paper. This tobacco paper is then rolled and processed into filaments, for example, in a rolling mill. A prescribed proportion of glycerin is added during the slurry preparation. However, an uncertain proportion of glycerin may be lost during the drying process. Therefore, subsequent control of the glycerin content is crucial for ensuring the quality of the final product.

[0004] A method for measuring the humidity value F of a dielectric material using at least one microwave resonator is known from DE102007041429A1. This method involves evaluating the shift of the resonant frequency A for at least two resonant modes, each with a different resonant frequency, and calculating a density-independent humidity value from the measured resonant frequency shift. It is known that the resonant frequency shift is measured for resonant frequencies that are far apart from each other. Here, the measurement is performed at one resonant frequency below 1 GHz, while the other resonant frequency shift is measured at a frequency above 7 GHz.

[0005] According to WO2017 / 080982A1, an apparatus and method for determining the proportion of at least one additive in a tobacco-containing substance are known. To determine the proportions of tobacco and water, two measurement parameters are obtained by an alternating electromagnetic field. Further explanation: To determine the proportion of at least one other additive, additional measurement parameters must be obtained by measurement with a second alternating electromagnetic field at a second measurement frequency. By measuring the measurement parameters—for example, the value and phase of the alternating electromagnetic field or the resonance shift and resonance broadening—at two independent measurement frequencies, a total of four measurement parameters are obtained, from which inferences about the weight proportions of tobacco, water, and said at least one additive can be derived. It is also noted that three measurement parameters are, in principle, sufficient to determine tobacco, water, and additives; however, four measurement parameters further improve the accuracy of the measurement. This method, known from the prior art, advantageously uses these at least four measurement parameters determined in a data processing device to determine humidity and the weight proportions of tobacco and additives as the optimal solution to an overdetermined system of equations, for example, the optimal solution with the least square error. Here, in addition to the humidity and weight proportion of tobacco, the weight proportion of additives can also be determined. Summary of the Invention

[0006] The object of this invention is to provide a method for measuring the content of additives in tobacco paper, the method providing the most accurate values ​​possible in a simple manner.

[0007] According to the present invention, the objective is achieved by a method according to the present invention for measuring the content of additives in tobacco paper for use in electronic cigarettes.

[0008] The method according to the invention aims to measure the additive content in tobacco paper for use in electronic cigarettes as accurately as possible. The additive content is determined in volume percent or weight percent. The tobacco paper is manufactured from additives, water, aromatic substances, and a pulpy substance of tobacco, wherein, preferably, the pulpy substance is dried into a single layer of tobacco paper after a winding step. Unpredictable amounts of additives and water escape during the drying process, thus necessitating measurement to determine the additive content of the tobacco paper. The measurement is performed using at least one microwave resonator having two resonant modes with two different resonant frequencies. The smaller of the two resonant frequencies is in a frequency range less than 1 GHz, and the larger of the two resonant frequencies has a value greater than 2 GHz, wherein the lower range can be in the lower microwave range of 800 MHz. For each of the two resonant frequencies, a density-independent humidity value is calculated, wherein the additive content is determined based on these two density-independent humidity values. The density-independent humidity values ​​are preferably density-independent humidity angles. The corresponding density-independent humidity values ​​are characterized in that they are independent of density and indicate the humidity in the measured material. Unlike existing techniques, instead of assembling four measurements into a system of equations, the values ​​obtained through the two resonance modes are processed into density-independent humidity values. By determining the additive content independently of tobacco content via a density-independent parameter (e.g., humidity angle), significantly more accurate values ​​can be obtained. Physically speaking, this means that evaluating state parameters, which appear as dense state variables, provides significantly better results compared to evaluating a wide range of state parameters.

[0009] Preferably, glycerol is used as an additive in the tobacco processing industry. It is precisely for glycerol that the moisture content, independent of density, provides very accurate results.

[0010] In a preferred embodiment, the glycerol content g is linearly determined by two humidity angles and an offset value. Importantly for the glycerol content g, both humidity values—that is, two humidity values ​​from resonant frequencies not only in the high-frequency range but also in the microwave range—contribute to the glycerol content.

[0011] In a further, preferred improvement, the humidity of the tobacco paper is measured based on the humidity value at the higher frequency. It is important to recognize that the measurement of the humidity of the tobacco paper depends only on the density-independent humidity value at the higher frequency, and any contribution from the lower resonant frequency is negligible. This characteristic is not observed precisely in the measurement of glycerol content, as the glycerol content depends on both humidity values.

[0012] In a preferred further improvement, the at least one microwave resonator is configured as a planar sensor. The planar sensor has a field emanating from the resonator that interacts with the object being measured. When using the planar sensor, tobacco paper is filtered on the flat sensor surface and conveyed through the measurement field.

[0013] In addition to planar sensors, gap sensors can also be provided in principle, in which tobacco paper is conveyed through the resonant cavity via a gap.

[0014] In one feasible implementation, the measurement can be performed directly on a single layer of tobacco paper. However, it has been found that the measurement can also be performed on tobacco paper wound into a tube. In principle, it is also feasible to perform both measurements sequentially. Alternatively or additionally, the measurement can also be performed during the drying process or directly after the drying process. Here, the measurement can be performed after the drying process is completed or at defined time points during the drying process.

[0015] In a preferred embodiment, it is feasible to measure the glycerol content of the tobacco paper before it is further processed into a bundle, i.e., before it enters the rolling machine.

[0016] The measurement method according to the invention is highly reliable and allows for control of the addition of water and / or glycerol to the slurry based on the measured humidity value. In this way, desired values ​​for both glycerol and humidity content can be adjusted.

[0017] In a preferred further improvement, the humidity value is a humidity angle. The humidity angle is determined as the quotient of the resonant frequency shift and the broadening of the half-value width. For the resonant frequency shift, the change in frequency (in Hertz) is compared between an empty resonator and a filled resonator. The half-value width of the resonance curve when the resonator is unfilled is also taken into consideration. Instead of the half-value width, other parameters caused by the damping of the resonance, such as the amplitude of the resonance curve, can also be considered. It has proven advantageous to determine the humidity angle as the arctangent of the density-independent quotient of the resonant frequency shift and the broadening of the half-value width. Attached Figure Description

[0018] The method according to the present invention will be described in more detail below with the aid of embodiments. In the figures:

[0019] Figure 1 The schematic diagram illustrates the location used for glycerol measurement in the initial stage.

[0020] Figure 2 This shows the possible locations for glycerin measurement in the winding machine.

[0021] Figure 3The measurements of the humidity angle for both modes, in relation to humidity content and glycerol content, are shown.

[0022] Figure 4 The results of the glycerol measurement are shown. Detailed Implementation

[0023] Figure 1 A mixer 10 is shown schematically, in which glycerol is mixed with water, binders, flavorings, other aerosol-forming additives, and tobacco to form a slurry for use in electronic cigarettes. This embodiment is based on glycerol, but other additives, with or without glycerol, can also be used and measured in the same manner. These ingredients are added in precisely defined proportions and processed in the mixer into a homogeneous mixture in slurry form. The resulting slurry is rolled in a roll press 12 and fed as a flat material to a dryer 14. The drying process takes place in the dryer 14, during which an indeterminate amount of water and glycerol is lost from the tobacco paper. The dried tobacco paper is rolled into a bobbin in 16. Possible measurement locations MP, for example, are in the dryer 14, along the path of the dried tobacco paper from the dryer 14 to the bobbin 16, and directly at the bobbin 16, for controlling humidity and measuring glycerol content. The obtained values ​​for glycerol content and / or humidity content can be reported back to the mixer 10 so that the glycerol content can be adjusted to the desired value. The humidity content can also be adjusted. The measured values ​​can also be used to match the parameters of the drying process to the desired values ​​for humidity and glycerin.

[0024] Figure 2 The diagram schematically illustrates how tobacco paper 18 unfolds from bobbin 16 along the conveying direction T. The tobacco paper is fed to winding machine 20 via conveyor roller 18. Paper 22 is also fed to winding machine 20 for bundling, forming a bundle in zone 24. A possible measuring position MP is located along the path from bobbin to winding machine 20, where additional paper is supplied to form the bundle.

[0025] Figure 3 The humidity values ​​(humidity content, in %) are plotted with respect to the humidity angle Φ for two frequencies: 0.9 GHz and 5.6 GHz. The humidity angle Φ is formed as the arctangent of the quotient B / A, where A describes the resonant frequency shift and B describes the broadening of the resonant curve.

[0026] The measurements were performed at different glycerol and humidity levels. The second measurement was conducted on the same material at a higher frequency.

[0027] Measurements at 5.6 GHz show that the humidity angle Φ is independent of the glycerol content of the sample and depends only on the humidity content. This is due to the proportionality of the humidity angle to the humidity content under different glycerol contents. Therefore, Figure 3 The regression line shown can be used as a calibration for humidity measurements that are independent of glycerol.

[0028] In contrast, measurements at 0.9 GHz show that the measured humidity angle Φ is related to both humidity content and glycerol content. Samples with the same glycerol content are characterized in the figure by separate linear regressions. To compensate for the effects of material humidity variations, humidity angle Φ at two frequencies must be considered for glycerol content measurements.

[0029] Figure 4 The results of the evaluation are shown, where a reference value for glycerol content is plotted relative to the measured glycerol values. Calculations were performed using the calibration equations listed below, with the humidity angle Φ at two frequencies. Good agreement between the individual values ​​and the fitted straight line can be clearly seen, where the measured values ​​deviate from the reference value by only a few percentage points.

[0030] For humidity measurement, a high-frequency Φ device is used. H The measured value of the resonant mode. One way to use it for the humidity value u is:

[0031] u=a1·Φ H +a2

[0032] Here, a1 and a2 represent calibration coefficients. If the calibration coefficients are determined, they can be derived from the measured humidity angle Φ. H Determine the humidity value directly.

[0033] Two humidity angle models were used to determine the glycerol content:

[0034] g=b1·Φ L +b2·Φ H +b3

[0035] Where b1, b2, and b3 are calibration coefficients. Importantly, both humidity angles are included as mass-independent parameters in the determination of glycerol content, and therefore the measurements of humidity and glycerol content are independent of the mass of the product being tested. Determining the mass fraction of the product being tested through potentially overdetermined equations, as in the prior art, compromises measurement accuracy. The additional determination of the tobacco fraction cannot be performed in the manner according to the invention (which is based on mass-independent measurement parameters).

Claims

1. A method for measuring the content of additives in tobacco paper for use in electronic cigarettes, said tobacco paper being made of additives, water, aromatic substances, and a pulpy substance of tobacco, wherein, The slurry material is dried into a single layer of tobacco paper, characterized in that the tobacco paper is measured with at least one microwave resonator having two resonant modes with two resonant frequencies, the smaller of the two resonant frequencies being in a frequency range of less than 1 GHz and the larger of the two resonant frequencies being in a microwave range of more than 2 GHz, and for each of the two resonant modes, a humidity value independent of density is calculated, and the glycerol content is determined based on the two humidity values.

2. The method according to claim 1, characterized in that, The additive consists entirely or partially of glycerol.

3. The method according to claim 1 or 2, characterized in that, The additive content depends linearly on two humidity values ​​and an offset value that are independent of density.

4. The method according to claim 1 or 2, characterized in that, The humidity of tobacco paper is measured based on a density-independent humidity value at the larger resonant frequency.

5. The method according to claim 1 or 2, characterized in that, The additive content is determined regardless of the quality of the tobacco paper.

6. The method according to claim 1 or 2, characterized in that, The at least one microwave resonator has a planar sensor.

7. The method according to claim 1 or 2, characterized in that, The at least one microwave resonator has a gap sensor.

8. The method according to claim 1 or 2, characterized in that, The measurements were performed on a single layer of tobacco paper.

9. The method according to claim 1 or 2, characterized in that, The measurements were taken on tobacco paper wound into a tube.

10. The method according to claim 1 or 2, characterized in that, The measurements are performed in the dryer or directly after the dryer.

11. The method according to claim 1 or 2, characterized in that, The measurement is performed in front of the rolling equipment.

12. The method according to claim 1 or 2, characterized in that, Water and / or glycerin are added to the paste based on at least one of the humidity values ​​that are independent of density.

13. The method according to claim 1 or 2, characterized in that, The humidity value is determined as the quotient of the widening of the half-value width and the resonant frequency shift, wherein empty resonators and filled resonators are compared with each other respectively.

14. The method according to claim 1 or 2, characterized in that, The humidity value is obtained as the arctangent of the quotient of the half-value width and the resonant frequency offset.

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