Characterization method for moisture interaction rule of components in dynamic moisture absorption process of cigarette

Abstract

The invention discloses a characterization method for a moisture interaction rule of each component in a cigarette dynamic moisture absorption process, which comprises the following steps of: detecting moisture in the whole cigarette and each component by adopting a low-field nuclear magnetic resonance technology and a nuclear magnetic resonance imaging technology, and constructing a relation model of the water absorption rate and the moisture absorption time of the cigarette; and a correlation model of the moisture peak areas of the whole cigarette and each component is established, so that the characterization method of the moisture interaction rule of each component in the dynamic moisture absorption process of the cigarette is established. The method provided by the invention is convenient and efficient, effectively solves the problem that the moisture content of each part of the cigarette is difficult to nondestructively detect and effectively predict, and provides technical support for processing and storage of the cigarette.

Description

Technical Field

[0001] The invention belongs to the field of online detection of cigarette moisture, and in particular relates to a method for characterizing the interaction law of moisture in various components during the dynamic moisture absorption process of cigarettes. Background Art

[0002] Cigarettes are usually composed of tobacco particles / tobacco shreds, paper tubes, filters and other components. Among them, tobacco particles / tobacco shreds are the core raw materials of tobacco products. Because they contain highly hydrophilic chemical components and pore structures, they are very easy to absorb moisture and regain moisture under different temperature and humidity environments, which has an adverse effect on the processing, production, transportation and storage of cigarette products. The wrapping of paper tubes can prevent tobacco particles / tobacco shreds from absorbing moisture from the environment to a certain extent, but the paper tube itself also has certain hygroscopic properties and can absorb moisture from wet tobacco particles / tobacco shreds, causing deterioration in the appearance of cigarettes. Therefore, clarifying the interaction of moisture in each component of a cigarette during the moisture absorption process plays an important guiding role in its quality evaluation, process design, and preservation methods.

[0003] As a fast, non-destructive and environmentally friendly moisture detection technology, Low Field Nuclear Magnetic Resonance (LF-NMR) can explain the moisture state and migration change rules inside the material from a microscopic perspective by analyzing the differences in the transverse relaxation time (T2) of the sample. Low-field nuclear magnetic resonance imaging (MRI) technology converts the moisture distribution data in the sample into a visual image, which can visually observe the moisture distribution inside the sample and detect the moisture flow inside the material in real time. It is of great significance for studying the migration and distribution of moisture inside the material.

[0004] At present, low-field nuclear magnetic resonance technology is mostly used in the tobacco field to determine the moisture content of tobacco. For example, patent CN106468670A discloses a tobacco moisture content test method based on time-domain nuclear magnetic resonance inversion peak area, and patent CN103837560A discloses a method for measuring tobacco moisture content using low-field nuclear magnetic resonance. Both do not involve research on the interaction of moisture in various components of cigarettes during dynamic moisture absorption.

[0005] Therefore, developing a simple and efficient method to characterize the interaction between moisture components in the dynamic moisture absorption process of cigarettes is of great significance to the production, processing and stable storage of cigarette products. Summary of the invention

[0006] The present invention provides a method for characterizing the interaction law of moisture in various components during the dynamic moisture absorption process of cigarettes. The method is convenient and efficient, and effectively solves the problem that the moisture status of various components in the existing cigarette moisture absorption process is difficult to detect non-destructively, and provides technical support for cigarette processing and storage.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A method for characterizing the interaction between moisture of various components in a cigarette during dynamic moisture absorption, which is characterized by: using low-field nuclear magnetic resonance technology to detect the entire cigarette and its components during the dynamic moisture absorption process, and constructing a correlation equation y1 between the water absorption rate of the cigarette and its components and the water adsorption peak area; by online testing the water peak area value during the dynamic moisture absorption process, the water absorption rate of the cigarette during the dynamic moisture absorption process is calculated based on y1, and the model is fitted with the moisture absorption time t to establish a correlation equation y2 between the water absorption rate and the moisture absorption time during the dynamic moisture absorption process of the cigarette; by the water peak area of ​​the cigarette and its components at different moisture absorption times, a correlation equation y3 between the water peak area of ​​the cigarette and its components is established, and the water peak area of ​​each component is calibrated with the water peak area of ​​the whole cigarette; using y1 and y3, a correlation equation y4 between the water absorption rate and the moisture absorption time of each component of the cigarette during the dynamic moisture absorption process is established; integrating the above fitting models, establishing a characterization model M1 for the interaction between moisture of various components in the cigarette during moisture absorption, and verifying the reliability of the model through low-field nuclear magnetic resonance imaging technology. Specifically including the following steps:

[0009] (1) Low-field nuclear magnetic resonance (LF-NMR) instrument calibration: Use the FID pulse sequence to measure the standard oil sample, calibrate the center frequency of the time domain nuclear magnetic resonance instrument and the pulse width of the 90° pulse, and clarify the instrument's sampling frequency, sampling times, sampling waiting time, analog gain, digital gain and accumulation times to ensure the stability and accuracy of the FID signal;

[0010] (2) Initial moisture detection of samples: Place the cigarette and its disassembled component samples in the magnet coil of a low-field nuclear magnetic resonance analyzer, select the CPMG sequence to collect the signal of the sample, invert the CPMG sequence attenuation spectrum obtained by software, calculate the moisture peak area A0 of the sample, and record the initial mass m0 of the sample;

[0011] (3) Construction of the correlation equation between the water absorption rate of cigarettes and their components after disassembly and the water adsorption peak area: the cigarettes to be tested and their components after disassembly are placed in LF-NMR sample tubes respectively, and the sample tubes containing the samples to be tested are placed in a drying dish containing the required distilled water or saturated salt solution. The sample tubes are taken out every 4 hours, weighed on an electronic balance and the mass m is recorded, and the water absorption rate of the sample to be tested after moisture absorption is calculated to be WA = (m-m0) / m0; the samples are placed in the LF-NMR magnet coil, and the CPMG sequence is selected to collect the signal of the samples. The obtained CPMG sequence attenuation spectrum is inverted by software to obtain the inversion spectrum, and then the corresponding transverse relaxation time-signal amplitude distribution curve and the total peak area A are obtained; the model is used to fit the correlation equation y1 between the water absorption rate WA of cigarettes and their components and the water adsorption peak area A-A0;

[0012] (4) Online moisture detection during dynamic moisture absorption process:

[0013] a) Relative humidity calibration of humidity control sample tube: Place the required distilled water or saturated salt solution in the tray of the humidity control sample tube, and use the humidity real-time detection device to calibrate the relative humidity in the sample tube. The calibration range is 0-100%;

[0014] b) Sample preparation: Place the cigarette to be tested in a low-field NMR humidity-controlled sample tube; Place distilled water or saturated salt solution in a tray in the humidity-controlled sample tube to provide the required moisture absorption environment, with an ambient humidity range of 10 to 98%; Place a rubber stopper on the mouth of the sample tube to seal it;

[0015] c) Online moisture detection: Place the sample to be tested in the magnet coil of a low-field nuclear magnetic resonance analyzer, select the CPMG sequence to perform automatic timed signal acquisition on the sample, with a specific time interval of 1 hour, and perform online continuous detection for 120 hours; Invert the CPMG sequence decay spectrum obtained by software to obtain an inversion spectrum, and then obtain the corresponding transverse relaxation time-signal amplitude distribution curve and moisture peak area;

[0016] (5) Analysis of the relationship between water absorption rate and moisture absorption time in the dynamic moisture absorption process: The water peak area obtained during the dynamic moisture absorption process of cigarettes is used to calculate the water absorption rate during the dynamic moisture absorption process of cigarettes according to the correlation equation y1, and the model is fitted with the moisture absorption time to establish the correlation equation y2 between the water absorption rate and moisture absorption time during the dynamic moisture absorption process of cigarettes;

[0017] (6) Dynamic relationship detection of moisture peak area of ​​cigarettes and their components during moisture absorption:

[0018] a) Relative humidity correction in hygroscopic environment: Place distilled water or saturated salt solution under the tray of a sealed drying dish, and use a real-time humidity detection device to calibrate the relative humidity in the sample tube. The calibration range is 10-98%;

[0019] b) Sample preparation: Place the cigarettes to be tested in a drying dish with constant humidity to absorb moisture and seal with white vaseline;

[0020] c) Sample moisture detection: After absorbing moisture for 0 to 120 hours, the cigarettes to be tested are taken out and placed in the magnet coil of a low-field nuclear magnetic resonance analyzer. The CPMG sequence is selected to collect signals from the samples. The obtained CPMG sequence attenuation spectrum is inverted by software to obtain an inversion spectrum, and then the corresponding transverse relaxation time-signal amplitude distribution curve and moisture peak area are obtained; then the cigarettes are split into cigarette particles and paper tubes, and the cigarette particles and paper tubes are placed in the magnet coil of a low-field nuclear magnetic resonance analyzer respectively, and the same method as above is used for detection;

[0021] d) establishing a correlation equation y3 of the moisture peak areas of the cigarette and its components through the moisture peak areas of the cigarette and its components at different moisture absorption times, and calibrating the moisture peak area of ​​each component with the moisture peak area of ​​the whole cigarette;

[0022] (7) Calculate the water absorption rate of the corresponding cigarette particles and paper tubes during the continuous dynamic moisture absorption process of the whole cigarette through y1 and y3, fit it with the time t, and obtain the correlation equation y4 between the water absorption rate and moisture absorption time of each component of the cigarette during the dynamic moisture absorption process;

[0023] (8) Integrate y1, y2, y3 and y4 to establish a characterization model M1 for the interaction between moisture components during the dynamic moisture absorption process of cigarettes;

[0024] (9) Using low-field nuclear magnetic resonance imaging technology, the HSE sequence was selected to record the moisture distribution of cigarettes during the dynamic moisture absorption process to verify the reliability of the moisture interaction law.

[0025] Furthermore, the specific parameters of the CPMG sequence are set as follows: magnetic field center temperature 32.00±0.02℃; main frequency = 21MHz; sampling frequency = 100kHz; analog gain = 20.0dB; digital gain = 3; RF delay = 0.08ms; 180° pulse width = 8.40μs; sampling waiting time = 6500ms; echo time = 0.4ms; number of echoes = 16000; accumulation times = 16; pre-amplification gear = 1; select the number of iterations of 10 million times for data inversion to obtain the inversion spectrum, and then obtain the corresponding transverse relaxation time-signal amplitude distribution curve and combined water peak area.

[0026] Furthermore, the specific parameters of the HSE sequence are set as follows: FlipAngle=90.0deg; RefocusFlip Angle=180deg; RG=10.0dB; PRG=3; DRG=5dB; Phase Encoding Duration=1.00ms; Sweep Width=40KHz; Dummy Scan=0; TR=500.00ms; TE=2.44ms; Average=4; Read Size=256; Phase Size=192; Echo Position=10%, and the obtained signal graph is dyed to obtain the corresponding cigarette moisture distribution graph.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The method of the present invention is convenient and efficient, and effectively solves the problem that it is difficult to non-destructively detect the moisture content of each component during the moisture absorption process of existing cigarettes, and provides technical support for cigarette processing and storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is the relationship between the water absorption rate of cigarettes and the water adsorption peak area;

[0030] Figure 2 is the relationship between the water absorption rate of smoke particles and the water adsorption peak area;

[0031] Figure 3 is the relationship between the water absorption rate of the paper tube and the water adsorption peak area;

[0032] Figure 4 The relationship between the moisture peak area and the moisture absorption time of the continuous moisture absorption of cigarettes;

[0033] Figure 5 The relationship between the water absorption rate of continuous hygroscopic smoke particles and the hygroscopic time;

[0034] Figure 6 The relationship between the water absorption rate and the absorption time of the continuous moisture absorption paper tube;

[0035] Figure 7 is the relationship between the peak area of ​​moisture in smoke particles and the peak area of ​​moisture in whole smoke;

[0036] Figure 8 is the relationship between the moisture peak area of ​​the paper tube and the moisture peak area of ​​the whole cigarette;

[0037] Fig. 9 These are the nuclear magnetic resonance images of cigarettes after different moisture absorption times. DETAILED DESCRIPTION

[0038] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0039] Example 1: Characterization of the interaction between the moisture content of whole cigarette and its components during the dynamic moisture absorption process of cigarette at 95% relative humidity

[0040] (1) Instrument calibration: The standard oil sample is measured using the FID pulse sequence to calibrate the center frequency of the time domain nuclear magnetic resonance instrument and the pulse width of the 90° pulse. Among them, the sampling frequency is 100 khz, the center frequency of the nuclear magnetic resonance instrument is 21 MHz, the 90° pulse width is 4 to 6 μs, the number of sampling points is 1024, the interval between adjacent repeated scans is 1000 ms, the RF delay is 0.08 ms, the analog gain is 20 db, the digital gain is 3, and the number of accumulations is 8.

[0041] (2) Moisture detection of initial cigarettes and their components: Place unmoistened cigarettes, cigarette particles and paper tube samples in the magnet coil of a low-field nuclear magnetic resonance analyzer, respectively, and select the CPMG sequence to collect signals from the samples. The specific parameters of the CPMG sequence are as follows: magnetic field center temperature 32.00±0.02℃; main frequency = 21MHz; sampling frequency = 100kHz; RF delay = 0.08ms; 180° pulse width = 8.40μs; waiting time = 6500ms; echo time = 0.4ms; number of echoes = 16000; accumulation times = 16; pre-release gear = 1. Select the number of iterations to perform data inversion for 10 million times to obtain the inversion spectrum, and then calculate the total peak area A0 of the cigarette and its components (the complete cigarette is recorded as A T0 , smoke particles are recorded as A TG0 , the paper tube is marked as A TP0 ); In addition, weigh the initial mass m0 of the unmoisturized sample (the complete cigarette is recorded as m T0 , smoke particles are denoted as m TG0 , the paper tube is denoted as m TP0 ).

[0042] (3) Construction of the correlation equation between the water absorption rate of cigarettes and their components and the water adsorption peak area: The sample to be tested is placed in an LF-NMR sample tube, and the sample tube containing the sample to be tested is placed in a drying dish containing distilled water (the measured humidity is 95%). The sample tube is taken out every 4 hours, and it is placed on an electronic balance for weighing and the water absorption rate of the sample to be tested after moisture absorption is calculated; it is placed in the LF-NMR magnet coil, and the CPMG sequence is selected to collect the signal of the sample. The obtained CPMG sequence attenuation spectrum is inverted by software to obtain the inversion spectrum, and then the corresponding transverse relaxation time-signal amplitude distribution curve and total peak area A (the complete cigarette is recorded as A T , smoke particles are recorded as A TG , the paper tube is marked as A TP ). The model fitting is used to construct the correlation between the water absorption rate WA ((m-m0) / m0) and the water adsorption peak area ΔA (A-A0). Through fitting, it is obtained that the relationship y1 between the water absorption rate of the whole cigarette and the water adsorption peak area is: y 1T =8185.39135x+346.46765, R 2 =0.99752( Figure 1 ), the relationship between smoke particle water absorption rate and water adsorption peak area 1TG is: y = 4493.47097x + 53.05408, R 2 =0.99584( Figure 2 ), the relationship between the water absorption rate of the paper tube and the water adsorption peak area y1 is: y 1TP =3137.5516x+69.17746, R 2=0.99939( Figure 3 ), where x is the water absorption rate of a single whole cigarette, cigarette particles and paper tube (g / g), and y is the corresponding water adsorption peak area. The determination coefficients of the linear fitting curves are all greater than 0.99, indicating that there is a good correspondence between the water adsorption peak area and the water absorption rate, and its change trend can be predicted by the linear fitting model.

[0043] (4) Online moisture detection during dynamic moisture absorption process:

[0044] a) Relative humidity calibration of humidity control sample tube: Distilled water is placed in the tray of the humidity control sample tube, and the relative humidity in the sample tube is calibrated using a USB-logger. After calibration, the equilibrium humidity is 95%.

[0045] b) Sample preparation: Place the cigarettes to be tested in a low-field NMR humidity-controlled sample tube. Place distilled water in the tray of the humidity-controlled sample tube to provide an ambient humidity of 95%; Place a rubber stopper on the mouth of the sample tube to seal it.

[0046] c) Online moisture detection: Place the sample tube to be tested in the magnet coil of the low-field nuclear magnetic resonance analyzer, and use the Q-FID sequence to debug the standard oil sample; select the CPMG sequence to perform timed automatic signal acquisition on the sample, with a specific time interval of 1h, and online continuous detection for 120h. The specific parameters of the CPMG sequence are set as follows: magnetic field center temperature 32.00±0.02℃; main frequency = 21MHz; sampling frequency = 100kHz; RF delay = 0.08ms; 180° pulse width = 8.40μs; waiting time = 6500ms; echo time = 0.4ms; number of echoes = 16000; pre-release gear = 1; accumulation times = 16. Select the number of iterations of 10 million times to perform data inversion to obtain the inversion spectrum, and then obtain the corresponding transverse relaxation time-signal amplitude distribution curve and moisture peak area. In an environment of 95% relative humidity, the relationship between the moisture peak area and moisture absorption time obtained during the continuous moisture absorption process of cigarettes is y = 901.31617x 0.28899 , R 2 =0.99518( Figure 4 ), where y is the moisture peak area and x is the moisture absorption time (h).

[0047] (5) Analysis of the relationship between water absorption rate and moisture absorption time in dynamic moisture absorption process: The water peak area obtained in the dynamic moisture absorption process of cigarettes is calculated according to the correlation equation y 1T , the water absorption rate of cigarettes in the dynamic moisture absorption process is calculated, and the model is fitted with the moisture absorption time to establish the correlation equation y2 between the water absorption rate and moisture absorption time in the dynamic moisture absorption process of cigarettes: y2 = 0.0659x 0.36678 -0.10052, R 2=0.99762. Where y is the water absorption rate of the whole cigarette, and x is the moisture absorption time (h).

[0048] The determination coefficient of the linear fitting curve is greater than 0.99, which indicates that the relationship between the moisture peak area and water absorption rate during the moisture absorption process of cigarettes and the moisture absorption time conforms to the fitting function, and the model can be established well.

[0049] (6) Dynamic relationship detection of moisture peak area of ​​cigarettes and their components during moisture absorption:

[0050] a) Relative humidity correction in hygroscopic environment: Distilled water is placed under the tray of a sealed drying dish, and the relative humidity in the sample tube is corrected using a USB-logger. After correction, the equilibrium humidity is 95%.

[0051] b) Sample moisture absorption: Place the cigarette sample to be tested in a drying dish at a relative humidity of 95% to absorb moisture, and seal the drying dish with white vaseline;

[0052] c) Sample moisture detection: After absorbing moisture for 0 to 120 hours, the cigarettes to be tested are taken out and placed in the magnet coil of a low-field nuclear magnetic resonance analyzer. The CPMG sequence is used to collect signals from the samples. The obtained CPMG sequence attenuation spectrum is inverted by software to obtain an inversion spectrum, and then the corresponding transverse relaxation time-signal amplitude distribution curve and moisture peak area are obtained. The cigarettes are then split into cigarette particles and paper tubes. The cigarette particles and paper tubes are placed in the magnet coil of a low-field nuclear magnetic resonance analyzer respectively, and the same method as above is used for detection.

[0053] d) Establish the correlation equation y3 of the moisture peak area of ​​the cigarette and its components at different moisture absorption times, and calibrate the moisture peak area of ​​each component with the moisture peak area of ​​the whole cigarette. Where:

[0054] The fitting equation for the moisture peak area of ​​whole smoke and smoke particles is: y = (3.9846E-8) x 3 -(5.18797E-4)x 2 +2.26326x-1212.92168,R 2 =0.99152( Figure 7 ), where x is the peak area of ​​moisture in the whole smoke and y is the peak area of ​​moisture in the smoke particles;

[0055] The fitting equation for the moisture peak area of ​​whole cigarette and paper tube is: y = (1.00919E-4) x 2 -0.15413x+264.58425, R 2 =0.99026( Figure 8 ), where x is the moisture peak area of ​​the whole cigarette, and y is the moisture peak area of ​​the paper tube;

[0056] The determination coefficients of the linear fitting curves are all greater than 0.99, which indicates that during the moisture absorption process of cigarettes, the moisture peak area of ​​the entire cigarette and the moisture peak area of ​​each component have an obvious regularity, which can be well summarized by the above function.

[0057] (7) Using y1 and y3, the water absorption rate of the corresponding cigarette particles and paper tubes during the continuous dynamic moisture absorption process of the whole cigarette is calculated and fitted with time t to obtain the correlation equation y4 between the water absorption rate and moisture absorption time of each component of the cigarette during the dynamic moisture absorption process, where:

[0058] The correlation equation between smoke particle water absorption rate and moisture absorption time is: R 2 =0.9984( Figure 5 ), where y is the water absorption rate and x is the moisture absorption time (h).

[0059] The correlation equation between the water absorption rate of paper tube and the moisture absorption time is: y = 0.00209x - 0.0027, R 2 =0.99607( Figure 6 ), where y is the water absorption rate and x is the moisture absorption time (h).

[0060] The determination coefficients of the linear fitting curves are all greater than 0.99, which indicates that the fitting equation can better express the relationship between the water absorption rate and moisture absorption time of each component of the cigarette.

[0061] (8) Through y1, y2, y3 and y4, the model M1 for calibrating the moisture content of each component with the moisture content of the whole cigarette can be obtained as follows:

[0062] a) During the continuous moisture absorption process of cigarettes in an environment with a relative humidity of 95%, the relationship between the water absorption rate of cigarettes and their components and the moisture absorption time is:

[0063] WA T =0.0659t 0.36678 -0.10052

[0064]

[0065] WA TP =0.00209t-0.0027

[0066] Among them, WA T is the water absorption rate of the whole cigarette, WA TG is the water absorption rate of smoke particles, WA T is the water absorption rate of the paper tube, t is the moisture absorption time. The linear range of t is 8-120h.

[0067] b) Correlation of the moisture peak area of ​​the whole cigarette and its components during dynamic moisture absorption:

[0068]

[0069] Among them A T is the moisture peak area of ​​the whole cigarette, A TG is the moisture peak area of ​​smoke particles, A TP is the moisture peak area of ​​the paper tube. The linear range of AT is 1033-4046. This set of equations is suitable for measuring the moisture peak area of ​​cigarettes and can predict the change trend of the moisture peak area of ​​cigarette particles and paper tubes under different relative humidity and moisture absorption time.

[0070] c) Correlation between low-field nuclear magnetic water adsorption peak area and water absorption rate of cigarettes and their components:

[0071] ΔA T =8185.39135WA T +346.46765

[0072] ΔA TG =4493.4709WA TG +53.05408

[0073] ΔA TP =3137.5516WA TP +69.17746

[0074] Where ΔA T is the moisture adsorption peak area of ​​the whole cigarette, i.e. A T -A T0 ; ΔA TG is the water adsorption peak area of ​​smoke particles, that is, A TG -A TG0 ; ΔA TP is the moisture peak area of ​​the paper tube, i.e. A TP -A TP0 WA T is the water absorption rate of the whole cigarette, WA TG is the water absorption rate of smoke particles, WA T It is the water absorption rate of paper tube.

[0075] (9) After 0-24 hours of moisture absorption, the cigarette samples to be tested are taken out and placed in the magnet coil of a low-field nuclear magnetic resonance analyzer. The HSE sequence is used to collect signals from the samples. The image is the 1H proton density image during the moisture absorption process of the cigarette, which can represent the moisture distribution in the cigarette sample. Fig. 9 The figure shows the moisture distribution of the cigarette after 0-24 hours of moisture absorption. It can be seen that both the cigarette particles and the paper tube have hygroscopic properties, and the cigarette particles have a stronger ability to adsorb moisture. In addition, the paper tube part close to the cigarette particles shows a stronger moisture signal.

[0076] Comparative Example 1 Prediction of water absorption rate of each component of heated cigarette during moisture absorption at 95% relative humidity

[0077] (1) Initial mass of cigarette and its components: The initial mass of the unmoistened cigarette, tobacco particles and paper tube was weighed separately. The initial mass of the complete cigarette was recorded as m T0 , smoke particles are denoted as m TG0 , the paper tube is denoted as m TP0 .

[0078] (2) Sample moisture absorption: The cigarette sample to be tested is placed in a drying dish at a relative humidity of 95% to absorb moisture, and the drying dish is sealed with white vaseline.

[0079] (3) The sample to be tested is placed in a drying dish at a relative humidity of 95%, and the sample is taken out after every 24 hours and 48 hours, respectively. The sample is placed on an electronic balance for weighing and the water absorption rate of the cigarette sample to be tested after dynamic moisture absorption is calculated as WA = (m-m0) / m0.

[0080] (4) Prediction and analysis of water absorption rate of whole cigarettes and their components during continuous moisture absorption of cigarettes As shown in Table 1, the same batch of samples continuously absorbed moisture under the same relative humidity of 95%. The actual test results were similar to the predicted results calculated by the model in Example 1, which proved that the model can better predict the water absorption rate of heated cigarettes.

[0081] Table 1: Model prediction and actual measurement results of continuous moisture absorption of heated cigarettes (water absorption rate)

[0082]

[0083] Comparative Example 2 Prediction of moisture peak area of ​​whole cigarette and each component of heated cigarette at different relative humidity

[0084] The experimental method includes the following steps:

[0085] (1) Instrument calibration: Use FID pulse sequence to measure standard oil samples, calibrate the center frequency of the time domain nuclear magnetic resonance instrument and the pulse width of the 90° pulse. Among them, the sampling frequency is 100khz, the center frequency of the nuclear magnetic resonance instrument is 21MHz, the 90° pulse width is 4-6μs, the number of sampling points is 1024, the interval between adjacent repeated scans is 1000ms, the RF delay is 0.08ms, the analog gain is 20db, the digital gain is 3, the accumulation times is 8, and the pre-stage gear is 1.

[0086] (2) Sample moisture absorption: The cigarette sample to be tested is placed in a drying dish at a relative humidity of 10-95% to absorb moisture, and the drying dish is sealed with white vaseline.

[0087] (3) Sample moisture detection: After absorbing moisture, the cigarette samples to be tested are taken out and placed in the magnet coil of a low-field nuclear magnetic resonance analyzer. The CPMG sequence is selected to collect signals from the samples. The CPMG sequence attenuation spectrum obtained is inverted by software to obtain the inversion spectrum, and then the corresponding transverse relaxation time-signal amplitude distribution curve and moisture peak area are obtained. After the whole cigarette measurement is completed, the whole cigarette is split into paper shell, cigarette particles, and other components, and the moisture peak area of ​​each component is measured in the same way.

[0088] (4) The prediction analysis of the moisture peak area of ​​the whole cigarette and its components during the dynamic moisture absorption process of cigarettes is shown in Table 2. The same batch of samples absorbed moisture under different relative humidity conditions, and the moisture peak area of ​​the cigarette particles and paper tubes was calculated by combining the low-field nuclear magnetic resonance moisture peak area of ​​the whole heated cigarette with the model in Example 1. The prediction results are very close to the actual measurement results, proving that this model can be applied to non-destructive moisture detection of heated cigarette components.

[0089] Table 2 Model prediction and actual measurement results of dynamic moisture absorption of heated cigarettes (peak area)

[0090]

[0091] The above embodiments are all exemplary embodiments of the present invention and are not intended to limit the present invention in any way. Therefore, according to the overall concept of the present invention, any adjustment or modification made by a person skilled in the art to the described process parameters shall fall within the protection scope of the present invention as long as it does not deviate from the concept of the invention or exceed the scope defined by the claims.

Claims

1. A method for characterizing the interaction between moisture components of a cigarette during dynamic moisture absorption, characterized in that: During the dynamic moisture absorption process, low-field nuclear magnetic resonance technology was used to detect the cigarette as a whole and each component, and the correlation equation y1 between the water absorption rate of the cigarette and each component of the cigarette and the moisture adsorption peak area was constructed; the water absorption rate of the cigarette in the dynamic moisture absorption process was calculated based on y1 by online testing of the moisture peak area value during the dynamic moisture absorption process, and the model was fitted with the moisture absorption time t to establish the correlation equation y2 between the water absorption rate and the moisture absorption time during the dynamic moisture absorption process of the cigarette; the moisture peak area correlation equation y3 of the cigarette and its components at different moisture absorption times was established, and the moisture peak area of ​​each component was calibrated with the moisture peak area of ​​the whole cigarette; the correlation equation y4 between the water absorption rate and moisture absorption time of each component of the cigarette in the dynamic moisture absorption process was established using y1 and y3; the above fitting models were integrated to establish a characterization model M1 for the moisture interaction law of each component in the cigarette moisture absorption process, and the reliability of the model was verified by low-field nuclear magnetic resonance imaging technology.

2. The method for characterizing the interaction law of moisture in each component of a cigarette during dynamic moisture absorption according to claim 1, characterized in that: The steps include: (1) Low-field nuclear magnetic resonance (LF-NMR) instrument calibration: Use the FID pulse sequence to measure the standard oil sample, calibrate the center frequency of the time domain nuclear magnetic resonance instrument and the pulse width of the 90° pulse, and clarify the instrument's sampling frequency, sampling times, sampling waiting time, analog gain, digital gain and accumulation times to ensure the stability and accuracy of the FID signal; (2) Initial moisture detection of samples: Place the cigarette and its disassembled component samples in the magnet coil of a low-field nuclear magnetic resonance analyzer, select the CPMG sequence to collect the signal of the sample, invert the CPMG sequence attenuation spectrum obtained by software, calculate the moisture peak area A0 of the sample, and record the initial mass m0 of the sample; (3) Construction of the correlation equation between the water absorption rate of cigarettes and their components after disassembly and the water adsorption peak area: the cigarettes to be tested and their components after disassembly are placed in LF-NMR sample tubes respectively, and the sample tubes containing the samples to be tested are placed in a drying dish containing the required distilled water or saturated salt solution. The sample tubes are taken out every 4 hours, weighed on an electronic balance and the mass m is recorded, and the water absorption rate of the sample to be tested after moisture absorption is calculated to be WA = (m-m0) / m0; the samples are placed in the LF-NMR magnet coil, and the CPMG sequence is selected to collect the signal of the samples. The obtained CPMG sequence attenuation spectrum is inverted by software to obtain the inversion spectrum, and then the corresponding transverse relaxation time-signal amplitude distribution curve and the total peak area A are obtained; the model is used to fit the correlation equation y1 between the water absorption rate WA of cigarettes and their components and the water adsorption peak area A-A0; (4) Online moisture detection during dynamic moisture absorption process: a) Relative humidity calibration of humidity control sample tube: Place the required distilled water or saturated salt solution in the tray of the humidity control sample tube, and use the humidity real-time detection device to calibrate the relative humidity in the sample tube. The calibration range is 0-100%; b) Sample preparation: Place the cigarette to be tested in a low-field NMR humidity-controlled sample tube; Place distilled water or saturated salt solution in a tray in the humidity-controlled sample tube to provide the required moisture absorption environment, with an ambient humidity range of 10 to 98%; Place a rubber stopper on the mouth of the sample tube to seal it; c) Online moisture detection: Place the sample to be tested in the magnet coil of a low-field nuclear magnetic resonance analyzer, select the CPMG sequence to perform automatic timed signal acquisition on the sample, with a specific time interval of 1 hour, and perform online continuous detection for 120 hours; Invert the CPMG sequence decay spectrum obtained by software to obtain an inversion spectrum, and then obtain the corresponding transverse relaxation time-signal amplitude distribution curve and moisture peak area; (5) Analysis of the relationship between water absorption rate and moisture absorption time in the dynamic moisture absorption process: The water peak area obtained during the dynamic moisture absorption process of cigarettes is used to calculate the water absorption rate during the dynamic moisture absorption process of cigarettes according to the correlation equation y1, and the model is fitted with the moisture absorption time to establish the correlation equation y2 between the water absorption rate and moisture absorption time during the dynamic moisture absorption process of cigarettes; (6) Dynamic relationship detection of moisture peak area of ​​cigarettes and their components during moisture absorption process: a) Relative humidity correction in hygroscopic environment: Place distilled water or saturated salt solution under the tray of a sealed drying dish, and use a real-time humidity detection device to calibrate the relative humidity in the sample tube. The calibration range is 10-98%; b) Sample preparation: Place the cigarettes to be tested in a drying dish with constant humidity to absorb moisture and seal with white vaseline; c) Sample moisture detection: After absorbing moisture for 0 to 120 hours, the cigarettes to be tested are taken out and placed in the magnet coil of a low-field nuclear magnetic resonance analyzer. The CPMG sequence is selected to collect signals from the samples. The obtained CPMG sequence attenuation spectrum is inverted by software to obtain an inversion spectrum, and then the corresponding transverse relaxation time-signal amplitude distribution curve and moisture peak area are obtained; then the cigarettes are split into cigarette particles and paper tubes, and the cigarette particles and paper tubes are placed in the magnet coil of a low-field nuclear magnetic resonance analyzer respectively, and the same method as above is used for detection; d) establishing a correlation equation y3 of the moisture peak areas of the cigarette and its components through the moisture peak areas of the cigarette and its components at different moisture absorption times, and calibrating the moisture peak area of ​​each component with the moisture peak area of ​​the whole cigarette; (7) Calculate the water absorption rate of the corresponding cigarette particles and paper tubes during the continuous dynamic moisture absorption process of the whole cigarette through y1 and y3, fit it with the time t, and obtain the correlation equation y4 between the water absorption rate and moisture absorption time of each component of the cigarette during the dynamic moisture absorption process; (8) Integrate y1, y2, y3 and y4 to establish a characterization model M1 for the interaction between moisture components during the dynamic moisture absorption process of cigarettes; (9) Using low-field nuclear magnetic resonance imaging technology, the HSE sequence was selected to record the moisture distribution of cigarettes during the dynamic moisture absorption process to verify the reliability of the moisture interaction law.

3. The method for characterizing the interaction law of moisture in each component of a cigarette during dynamic moisture absorption according to claim 2, characterized in that: The specific parameters of the CPMG sequence are as follows: magnetic field center temperature 32.00±0.02℃; main frequency = 21MHz; sampling frequency = 100kHz; analog gain = 20.0dB; digital gain = 3; RF delay = 0.08ms; 180° pulse width = 8.40μs; sampling waiting time = 6500ms; echo time = 0.4ms; number of echoes = 16000; accumulation times = 16; pre-amplification gear = 1; select the number of iterations of 10 million times for data inversion to obtain the inversion spectrum, and then obtain the corresponding transverse relaxation time-signal amplitude distribution curve and combined water peak area.

4. The method for characterizing the interaction law of moisture in each component of a cigarette during dynamic moisture absorption according to claim 2, characterized in that: The specific parameter settings used in the HSE sequence are as follows: FlipAngle = 90.0deg; Refocus FlipAngle = 180deg; RG=10.0dB; PRG=3; DRG=5dB; Phase Encoding Duration=1.00ms; Sweep Width=40KHz; Dummy Scan=0; TR=500.00ms; TE=2.44ms; Average=4; Read Size=256; PhaseSize=192; Echo Position = 10%, the obtained signal graph is dyed to obtain the corresponding cigarette moisture distribution graph.

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