A method of reducing the temperature of a cigarette burn cone

Abstract

The application discloses a method for reducing the temperature of a cigarette burning cone, which comprises adding calcium acetate solution into tobacco, drying the tobacco to obtain added tobacco, and rolling the added tobacco into a cigarette which can be ignited and smoked, wherein the calcium acetate solution is a saturated water solution containing calcium acetate, the mass fraction of calcium acetate in the saturated water solution is 30-37%, and the content of calcium acetate in the added tobacco is 10-40% of the mass of the tobacco. The method can greatly reduce the temperature of the cigarette burning cone by adding calcium acetate into the tobacco, thereby greatly reducing the release of harmful components of the cigarette product. The method does not damage the shape of the cigarette, can solve the problem that the added substances cannot fall off along with the burning of the cigarette, and is simple in preparation method, can utilize the existing equipment in production, and is easy to realize in process.

Description

Technical Field

[0001] This invention belongs to the field of cigarette technology, specifically relating to a method for reducing the temperature of a cigarette combustion cone. Background Technology

[0002] Smoking is harmful to health, and reducing the release of harmful components from cigarette products has been a technical challenge that those skilled in the art have long sought to solve. There are many ways to solve this problem, and lowering the temperature of the cigarette combustion cone is one effective method to reduce the release of harmful components. CN106723324B discloses a method for preparing cooled cigarettes, which involves sintering ground metal powder into metal rods according to certain process parameters, then wrapping them with tobacco and cigarette paper before connecting them to a filter to obtain the cigarette product. This method lowers the combustion cone temperature and simultaneously reduces the release of harmful substances in the smoke. Advantages include lowering the combustion cone temperature through heat conduction, and the fact that dense metal can fall off with the ash. However, those skilled in the art can easily recognize that while this method can be implemented in a laboratory, it cannot be efficiently mass-produced using machinery. This is because existing cigarette forming processes involve axial wrapping along the length, preventing the axial addition of a heat-conducting mechanism. In other words, only filamentous materials such as tobacco and stems can be wrapped with cigarette paper, not both rod-shaped and filamentous materials simultaneously. Even if machines are used to simultaneously wrap rod-shaped and filamentous materials, new problems arise, such as low production efficiency and poor stability of cigarette parameters (weight, draw resistance, ventilation rate). CN 111700307 A discloses a cigarette capable of reducing the temperature at the center of the combustion cone. Without adding external heat-conducting materials, it simply rearranges the tobacco shreds by adding thin tobacco sticks to the tobacco rod, enhancing the heat dissipation capacity at the center and reducing the temperature at the center of the combustion cone. It is foreseeable that the efficiency of producing this cigarette by machine may not be high enough. CN 109222224 A discloses a method for reducing the temperature of the cigarette combustion cone by adding metal foil filaments to the tobacco or fixing metal foil strips to the cigarette paper, achieving heat conduction. However, the technique of adding metal foil filaments to the tobacco cannot effectively solve the technical problems in this regard, because the cigarette is prone to extinguishing. Using metal foil strips fixed to cigarette paper, according to the instruction manual, involves aluminum, copper, silver, or gold foil strips. This significantly increases costs, and these heat-conducting materials have high melting points and cannot detach during cigarette combustion (although aluminum foil, with its lowest melting point, may not have this problem, its surface easily forms alumina with very low thermal conductivity, potentially hindering cooling). CN209768965U discloses a cigarette cooling sheet comprising a substrate layer and several coatings. The potassium citrate coating, when heated, can form organic potassium salts with biomolecules in the sheet, decomposing at high temperatures and then further burning, thus reducing the cigarette combustion temperature. The study "The Role of Potassium Salts in Tobacco Combustion" concludes that adding potassium salts to tobacco allows the heat generated during combustion to be released in batches, lowering the combustion temperature. The study "The Influence of Potassium Nitrate and Potassium Citrate on the Pyrolysis Kinetics and Combustion Characteristics of Typical Flue-cured Tobacco" shows that when the potassium ion addition ratio is 2%, potassium citrate reduces the maximum combustion temperature of flue-cured tobacco by 11.7%.These documents all indicate that potassium citrate can reduce the combustion temperature of cigarettes. However, it can be seen that although potassium citrate can reduce the combustion temperature of cigarettes, the reduction is very small and has no practical industrial application value in this field.

[0003] Calcium acetate is a food additive with good safety profile and is listed in the "YQ52—2015 List of Additives Permitted for Use in Tobacco Products". CN 1296789 A discloses a method for producing pollution-free cigarettes, which uses calcium acetate to react with nicotine to form harmless nicotine acetate, but it is ineffective against other harmful components generated at high temperatures. CN112501953 A describes the use of calcium acetate as a filler in cigarette paper to improve the whiteness of cigarette ash, but does not mention its use in reducing harm due to temperature variations. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for reducing the temperature of the cigarette combustion cone, which can reduce the release of harmful components from cigarette products.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention discloses a method for reducing the temperature of a cigarette combustion cone, comprising the following steps:

[0007] A calcium acetate solution is added to tobacco shreds and dried to obtain conditioned tobacco shreds, which are then rolled into cigarettes that can be lit and smoked.

[0008] In actual operation, the tobacco shreds are dried to a state close to that before feeding, and the allowable deviation of the moisture content compared with that before feeding is ±0.5%.

[0009] The inventors made an unexpected discovery: adding calcium acetate to tobacco can significantly reduce the temperature of the cigarette combustion cone, thereby greatly reducing the release of harmful components from cigarette products.

[0010] During the experimental exploration, the inventors also tried a series of additives such as potassium acetate, magnesium acetate, calcium citrate, calcium chloride, potassium citrate, and potassium carbonate. The inventors found that no matter how they added them, their overall effect was not as good as that of calcium acetate in this invention. Only by using calcium acetate can the resulting cigarettes not only significantly reduce the temperature of the cigarette combustion cone, but also avoid excessive flame retardancy which would destroy the temperature conditions for the self-sustaining combustion of the tobacco, and ultimately extinguish the cigarette.

[0011] Preferably, the calcium acetate solution is a saturated aqueous solution containing calcium acetate, wherein the mass fraction of calcium acetate in the saturated aqueous solution is 30% to 37%. In this invention, a saturated aqueous solution is used to reduce the amount of water added to the tobacco, thereby reducing energy consumption in the drying process.

[0012] Preferably, the calcium acetate content in the added tobacco is 10%-40% of the tobacco mass.

[0013] In a further preferred embodiment, the calcium acetate content in the added tobacco shreds is 20%-40% of the mass of the tobacco shreds.

[0014] More preferably, the calcium acetate content in the added tobacco is 30%-40% of the mass of the tobacco.

[0015] Preferably, the method for adding calcium acetate solution to tobacco is by uniform spraying.

[0016] The inventors discovered that when a calcium acetate solution is sprayed onto tobacco shreds using a spraying device, the metal salt precipitates on the surface of the tobacco shreds after drying and adheres to it to form a thin layer with very good uniformity.

[0017] Preferably, the drying temperature is 50℃-80℃.

[0018] Preferably, the number of temperature points in the high-temperature zone of 600℃-1000℃ during smoking of the cigarette is no higher than 60% of that of cigarettes without added calcium acetate.

[0019] The beneficial effects of this invention are:

[0020] 1. The preparation method is simple, and existing equipment can be used in production, making the process easy to implement.

[0021] 2. It can solve the problem of insufficient production efficiency.

[0022] 3. It does not damage the shape of the cigarette and can solve the problem that the substances added in existing technologies cannot be detached during the combustion of the cigarette.

[0023] 4. Production costs are significantly reduced. Attached Figure Description

[0024] Figure 1 The combustion cone temperature of cigarettes with different amounts of calcium acetate added to cigarette paper and tobacco is shown in green, with the high-temperature zone above 600℃ marked in green.

[0025] Figure 2 A line graph showing the temperature of the cigarette combustion cone in the embodiment.

[0026] Figure 3 Appearance of tobacco with calcium acetate added in different ways.

[0027] Figure 4 SEM images of tobacco shreds with calcium acetate added in different ways.

[0028] Figure 5 Graph of thermal analysis (TG / DSC) experimental results.

[0029] Figure 6The combustion cone temperature diagrams of cigarettes in Example 1 and Comparative Examples 1 and 3 show the high-temperature zone above 700℃ marked in green. Detailed Implementation

[0030] The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the invention to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and conventional methods in the art without departing from the above-described methodological spirit of the invention should be included within the scope of the invention.

[0031] Example 1

[0032] A saturated aqueous solution of calcium acetate is evenly sprayed onto the tobacco shreds, so that the amount of calcium acetate added is 10% of the weight of the tobacco shreds before adding the additive. The tobacco shreds are dried at 50°C until they are close to the state of the tobacco shreds before adding the additive, and then rolled into cigarettes using a cigarette rolling machine.

[0033] Example 2

[0034] A saturated aqueous solution of calcium acetate is evenly sprayed onto the tobacco shreds, so that the amount of calcium acetate added is 20% of the weight of the tobacco shreds before adding the additive. The tobacco shreds are dried at 60°C until they are close to the state of the tobacco shreds before adding the additive, and then rolled into cigarettes using a cigarette rolling machine.

[0035] Example 3

[0036] A saturated aqueous solution of calcium acetate is evenly sprayed onto the tobacco shreds, so that the amount of calcium acetate added is 30% of the weight of the tobacco shreds before adding the additive. The tobacco shreds are dried at 70°C until they are close to the state of the tobacco shreds before adding the additive, and then rolled into cigarettes by a cigarette rolling machine.

[0037] Example 4

[0038] A saturated aqueous solution of calcium acetate is evenly sprayed onto the tobacco shreds, so that the amount of calcium acetate added is 40% of the weight of the tobacco shreds before adding the additive. The tobacco shreds are dried at 80°C until they are close to the state of the tobacco shreds before adding the additive, and then rolled into cigarettes using a cigarette rolling machine.

[0039] Data detection:

[0040] Figure 1 The image shown is of a combustion cone captured by an infrared thermal imager. When the smoke extractor aspirates for 1 second, the high-temperature zone above 600℃ is marked in green. The image clearly shows that the area of ​​the high-temperature zone with added cooling agent is smaller compared to the blank sample. The degree of reduction can be quantified by counting the number of temperature points. A line graph was plotted based on the number of temperature points in different temperature ranges. Figure 2 As can be seen, the number of temperature points in the blank sample is higher in most temperature ranges, which is consistent with the phenomenon observed in the experiment. With increasing calcium acetate content, the number of high-temperature points above 600℃ decreases.

[0041] Table 1. Number of temperature points corresponding to the combustion cones of cigarettes with different amounts of calcium acetate added to the tobacco in different temperature ranges.

[0042]

[0043] Table 1 shows the number of temperature points on the combustion cone of cigarette samples prepared with tobacco containing 0%, 10%, 20%, 30%, and 40% calcium acetate, corresponding to different temperature ranges. Adding calcium acetate to the tobacco reduces the number of temperature points between 600℃ and 1000℃ on the combustion cone, indicating a decrease in temperature. Compared to the blank control (0%), when calcium acetate was added at 20%, 30%, and 40%, the percentage of temperature points between 600℃ and 1000℃ on the combustion cone was less than 50%.

[0044] Table 2. Number of temperature points corresponding to the combustion cones of cigarettes with different amounts of calcium acetate added to cigarette paper in different temperature ranges.

[0045]

[0046] Table 2 shows the number of temperature points on the combustion cone of cigarette samples prepared by adding 0%, 10%, 20%, 30%, and 40% calcium acetate to cigarette paper, corresponding to different temperature ranges. After adding calcium acetate to the cigarette paper, the number of temperature points on the combustion cone between 600℃ and 1000℃ did not decrease significantly, indicating minimal temperature change. This is likely due to the low proportion of added calcium acetate in the total amount of substances involved in combustion. Since the amount of tobacco in a cigarette is at least ten times the weight of the cigarette paper, cigarette paper is unsuitable as a carrier for calcium acetate in cigarettes, and the method of adding calcium acetate to cigarette paper to lower the combustion cone temperature is not feasible.

[0047] In addition to the above embodiments, the inventors also specifically investigated the effects of many metal salts on cigarette combustion. This invention lists the cooling effects of representative acetates (magnesium acetate, potassium acetate), representative calcium salts (calcium citrate, calcium chloride), and potassium salts (potassium citrate) on the combustion cone, and investigated the effects of different feeding methods on the cooling effect of the combustion cone.

[0048] The overall procedure of the experiment was to first add ingredients to the blank tobacco and then roll it into a cigarette.

[0049] Addition Method: The metal salt to be added is mixed into the tobacco shreds. The addition method varies depending on the solubility of the metal salt. For sparingly soluble salts, they are first ground into powder, passed through a 200-mesh sieve, and then weighed out in appropriate amounts according to the addition ratio, directly mixed mechanically with the tobacco shreds. For easily soluble metal salts, they are dissolved in water to prepare a saturated aqueous solution, which is then evenly sprayed onto the tobacco shreds and dried until they are close to the state of the tobacco shreds before addition. The allowable deviation in moisture content compared to before addition is ±0.5%. Using a saturated aqueous solution reduces the amount of water added to the tobacco shreds, thereby reducing energy consumption in the drying process.

[0050] Experiments have shown that 1. Whether the addition of metal salts to tobacco is uniform is a key condition for obtaining a significant cooling effect. The way metal salts are added to tobacco greatly affects the uniformity. The uniformity is very different when added in powder form and when added by solution spraying. Therefore, the properties of the metal salts themselves determine whether they can be added uniformly, which mainly refers to water solubility. (1) When metal salts that are difficult to dissolve in water are added to tobacco in powder form, some of the added material cannot adhere to the surface of the tobacco, resulting in uneven distribution in the cigarette space, with some parts having less and some parts having more. During the smoking process, when the cigarette burns to the part with less metal salt, it cannot play a role in reducing the temperature of the combustion cone; when it burns to the part with more metal salt, the salt will hinder the combustion of tobacco. Some salts are difficult to burn on their own, and some salts that have certain combustion-supporting properties will also weaken their combustion-supporting ability due to local aggregation. This is because the number of reaction sites on their own surface is insufficient, and the tobacco is blocked from contact with oxygen, which hinders the combustion of tobacco. At this point, the cigarette is very easy to extinguish, resulting in a quality defect. (2) Calcium acetate is a relatively water-soluble metal salt with a solubility of 30g-37g (0℃-100℃). After dissolving in water, it is sprayed onto the tobacco in the form of a solution using a spray device. After drying, the metal salt precipitates on the surface of the tobacco and adheres to it to form a thin layer with much better uniformity. Of course, there are also metal salts with even higher solubility, such as calcium chloride with a solubility of 59.5g-159g (0℃-100℃). However, the inventors conducted a large number of metal salt addition experiments and found that metal salts with particularly high solubility often have strong hygroscopicity. After being added to the tobacco and dried, they will absorb moisture from the air. Since water has a high specific heat capacity, it will greatly enhance the flame retardancy, making the cigarette very easy to extinguish.

[0051] To clarify the effect of additive uniformity on self-sustaining combustion, this invention investigated different additive methods. Figure 3 The images show the appearance of tobacco shreds with calcium acetate added in different ways. A. The blank control is a normal yellow color. B. The blank control, dried with water, is obtained by adding water to the tobacco shreds in the same way as the calcium acetate solution and then drying them; the color of the tobacco shreds is slightly darker. C. Adding 10% calcium acetate as anhydrous powder involves weighing dry calcium acetate powder and adding it to the tobacco shreds, then mechanically mixing it. Some calcium acetate will adhere to the surface of the tobacco shreds, making the tobacco shreds appear whiter. The tobacco shreds with 10% calcium acetate added appear slightly grayish-white, while the tobacco shreds with 40% calcium acetate added are whiter, indicating that more calcium acetate powder adheres. However, about one-third of the calcium acetate does not adhere to the tobacco shreds, and the actual amount added is much lower than the designed value. D. Adding 10% calcium acetate as an aqueous solution and F. Adding 40% calcium acetate as an aqueous solution both involve dissolving calcium acetate in water and then uniformly adding it to the tobacco shreds, then drying it in a 60℃ oven to a moisture content of 11%-13%. Figure 3As can be seen, the surface of the dried tobacco shreds is not white, but rather the original yellow has become a darker brown, indicating that powdered calcium acetate and solution calcium acetate adhere to the tobacco shreds in completely different ways. Figure 4 SEM images of tobacco shreds with calcium acetate added in different ways. Figure 4 Scanning electron microscopy results also confirmed the above statement.

[0052] 2. The flame-retardant properties of the metal salt itself are another crucial factor in determining whether it can be used to reduce the combustion cone temperature. Most non-combustible metal salts hinder tobacco combustion. Numerous experiments have shown that whether it's water-soluble sodium chloride and potassium chloride, or water-insoluble calcium carbonate and calcium citrate, cigarettes are prone to extinguishing. If flame retardancy is the sole approach to reducing the combustion cone temperature, the problem of cigarette extinguishing arises. The self-sustaining combustion of most substances generally occurs above 300℃; low-temperature combustion below 300℃ requires external heating, such as low-calorific-value gases produced in metallurgy and petrochemicals, or catalytic combustion of precious metals. Therefore, our goal is to find a substance to add to tobacco that promotes combustion at low combustion cone temperatures to prevent extinguishing, while inhibiting combustion at higher temperatures (during inhalation) to prevent further temperature increases. It is well known that the combustion cone temperature of a cigarette in a static state is approximately 600℃-700℃. During inhalation, the large amount of air inhaled promotes tobacco combustion, causing the combustion cone temperature to rise sharply, reaching instantaneous highs of over 900℃. Thermal analysis of calcium acetate shows that it decomposes at a relatively low temperature of 400℃-500℃. The decomposition product, acetone, is combustible and is an exothermic reaction. This prevents excessive flame retardation, which would disrupt the self-sustaining combustion temperature conditions of the tobacco, ultimately causing the cigarette to extinguish. At higher temperatures, it decomposes to form calcium carbonate, which inhibits combustion. The inventors discovered that calcium carbonate decomposes at 700℃ to produce carbon dioxide, inhibiting combustion and preventing the temperature of the combustion cone from rising during cigarette inhalation.

[0053] 3. Regarding potassium acetate, the inventors discovered through experiments that adding even a very small amount causes the cigarette to extinguish, likely due to its extremely strong hygroscopic properties. Regarding potassium citrate, the inventors found that adding a small amount does have a certain cooling effect, but the reduction is far less than that of calcium acetate. Table 3 shows that when the amount of potassium citrate added reaches 10% or more, a noticeable extinguishing phenomenon begins to appear. This is because it has a certain degree of hygroscopicity (see Table 4), and adding a slightly larger amount will cause the formation of water crystals due to moisture absorption, hindering the combustion of the tobacco. Its flame-retardant properties outweigh its combustion-supporting properties, therefore it cannot be added in large quantities. Calcium acetate does not cause cigarettes to extinguish significantly; even adding up to 40% will not result in a large number of extinguishings. The main reason can be seen from... Figure 5The search was conducted using DSC results. The experimental procedure was as follows: 2-5 mg of cooling agent sample was tested on a simultaneous thermal analyzer. The protective gas was helium at a flow rate of 60 mL / min, and the purge gases were air and helium at a flow rate of 20 mL / min. The heating rate was set to 20 °C / min. The water loss process and thermal decomposition changes of the cooling agent as the temperature increased were examined. Figure 5 As can be seen, acetone, an intermediate product of the thermal decomposition of calcium acetate, is flammable. Therefore, calcium acetate can be considered to have a certain degree of combustibility. Compared with potassium citrate and magnesium acetate, even with a larger addition amount of calcium acetate, flameout does not occur. The DSC results of magnesium acetate and potassium citrate did not show a large amount of exothermic phenomena between 400-500℃, indicating that they did not produce intermediate products that can burn or exothermically promote the combustion of the added tobacco, as calcium acetate does.

[0054] Therefore, it can be considered that potassium citrate has a limited effect on reducing the combustion cone temperature and is not industrially practical. Only calcium acetate, due to its own combustibility, can be added to a level of more than 30% without causing the cigarette to extinguish. This ensures that only calcium acetate can effectively reduce the combustion cone temperature of the cigarette, while also avoiding excessive flame retardancy that would destroy the self-sustaining combustion temperature conditions of the tobacco and ultimately cause the cigarette to extinguish.

[0055] Table 3. Effects of metal salts with different solubilities on cigarette extinguishing.

[0056]

[0057] 4. In addition, the inventors further investigated the deliquescence of different metal salts and conducted a hygroscopic weighing experiment in an environment of 40℃ and 80%RH. The results showed that calcium acetate had the lowest hygroscopicity, as shown in Table 4.

[0058] Table 4. Moisture absorption and weight gain of several metal salts at 40℃ and 80%RH

[0059] Potassium acetate Potassium citrate Calcium acetate Magnesium acetate 1min 1.74％ 0.10％ 0.19％ 0.14％ 10min 10.55％ 2.50％ 1.32％ 1.98％ 30min 23.16％ 5.99％ 1.46％ 4.38％ 60min 47.04％ 10.30％ 1.30％ 7.62％

[0060] Comparative Example 1

[0061] Other conditions were the same as in Example 1, except that the additive was potassium citrate, and the smoking results of the obtained cigarette were as follows. Figure 6 As shown.

[0062] Comparative Example 2

[0063] The other conditions are the same as in Example 2, except that the additive is potassium citrate, and the resulting cigarette cannot be smoked and goes out directly.

[0064] Comparative Example 3

[0065] Other conditions were the same as in Example 1, except that the additive was magnesium acetate, and the smoking results of the resulting cigarette were as follows. Figure 6As shown.

Claims

1. A method for reducing the temperature of a cigarette combustion cone, characterized in that: Includes the following steps: A calcium acetate solution is added to tobacco shreds and dried to obtain conditioned tobacco shreds, which are then rolled into cigarettes that can be lit and smoked. The calcium acetate solution is a saturated aqueous solution containing calcium acetate, wherein the mass fraction of calcium acetate in the saturated aqueous solution is 30% to 37%. The calcium acetate content in the added tobacco is 10%-40% of the tobacco mass; The method for adding calcium acetate solution to tobacco is to spray it evenly.

2. The method for reducing the temperature of a cigarette combustion cone according to claim 1, characterized in that: The calcium acetate content in the added tobacco is 20%-40% of the tobacco mass.

3. The method for reducing the temperature of a cigarette combustion cone according to claim 1, characterized in that: The drying temperature is 50℃-80℃.

4. The method for reducing the temperature of a cigarette combustion cone according to claim 1, characterized in that: When the cigarette is smoked, the number of temperature points in the high-temperature zone of 600℃-1000℃ in the combustion cone is no higher than 60% of that in cigarettes without added calcium acetate.

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