Reversibly color-changing pellet and method of making and using same

Abstract

The application provides a reversible color-changing pill core and a preparation method and application thereof. The reversible color-changing pill core is composed of a pill core core layer and a pill core shell layer in a mass ratio of 20: (1-3). The pill core shell layer is composed of a thermochromic pigment, a binder, a high-thermal-conductivity material and a low-thermal-conductivity material. By changing the proportion and amount of the high-thermal-conductivity material and the low-thermal-conductivity material, a pill core shell layer with different thermal conductivities can be obtained, so that the color-changing speed is controlled. The pill core core layer is composed of low, medium and high-thermal-conductivity materials and a binder. By changing the amount of the several components, the thermal conductivity of the pill core core layer is controlled, so that the color-reverting speed is controlled. Therefore, the reversible color-changing pill core realizes controllable color-changing and color-reverting speeds through the synergistic effect of the components in the pill core core layer, the synergistic effect of the components in the pill core shell layer and the synergistic effect of the pill core core layer and the pill core shell layer, and has good roundness and low friability.

Description

Technical Field

[0001] This invention relates to the field of functional materials, specifically to a reversible color-changing pellet core, its preparation method, and its application. Background Technology

[0002] With the development of society and the economy, the demand for cigarettes is constantly changing. To meet the increasingly diverse needs of consumers and enhance the consumer experience, various color-changing cigarette filters have emerged. These color-changing cigarette filters primarily involve adding color-changing particles to a transparent, hollow cigarette filter. The color-changing particles applied to the transparent filter allow consumers to visually perceive a reversible or irreversible color change effect in response to temperature, light, or the pH value of the smoke when smoking. This creates a unique type of special cigarette filter, where the color change serves as a visual signal and simultaneously increases the sensory enjoyment of smoking.

[0003] For example, Chinese invention patent application CN 115109320A discloses a color-changing granule for cigarettes, its preparation method, and its uses. The method involves mixing, extrusion molding, drying, and sieving to obtain the color-changing granules, which are then placed in a transparent hollow filter rod. This allows consumers to clearly perceive the granule color changing with temperature, light, or pH while smoking cigarettes. While this patent application achieves reversible color-changing functionality in the filter rod during cigarette smoking, it lacks technology for controlling the color-changing / returning speed. Summary of the Invention

[0004] The purpose of this invention is to provide a reversible color-changing pellet core that can freely control the color-changing and color-returning speed of the pellet core.

[0005] The second objective of this invention is to provide a method for preparing a reversible color-changing pellet core that allows for free control of the color-changing and color-returning speeds of the pellet core.

[0006] The third objective of this invention is to provide an application of the above-mentioned reversible color-changing pellet core in cigarettes to enhance the cigarette consumption experience.

[0007] To achieve the objective, the technical solution adopted by this invention is as follows:

[0008] A reversible color-changing pellet core is composed of a pellet core layer and a pellet core shell layer in a mass ratio of 20:(1-3). The pellet core layer is mainly composed of the following components in parts by weight: 10-98 parts of a first low thermal conductivity material, 1-50 parts of a medium thermal conductivity material, 1-50 parts of talc powder, 0-0.5 parts of a first high thermal conductivity material, and 0.1-1 parts of a first binder. The pellet core shell layer is mainly composed of the following components in parts by weight: 1-10 parts of a thermochromic pigment, 1-5 parts of a second high thermal conductivity material, 0-5 parts of a second low thermal conductivity material, and 0.1-1 parts of a second binder. The thermal conductivity of the first and second low thermal conductivity materials is less than 0.05 W / m*K, the thermal conductivity of the medium thermal conductivity material is 0.1-1.0 W / m*K, and the thermal conductivity of the first and second high thermal conductivity materials is 100-300 W / m*K.

[0009] If the amount of core layer is large, and the mass ratio of the two is greater than 20:1, the reversible color-changing core will return color quickly, and the color change may not be easily observed, making the color return speed uncontrollable. If the amount of shell layer is large, and the mass ratio of the two is less than 20:3, the reversible color-changing core will return color slowly. Even if the reversible color-changing core is used in cigarettes, it will be difficult to observe the color return of the reversible color-changing core until the cigarette is finished. Therefore, the preferred mass ratio of the core layer to the shell layer is 20:(1-3).

[0010] In this process, various thermally conductive materials in the core layer work together to regulate the color return rate of the reversible color-changing pellet. Similarly, various thermally conductive materials in the shell layer work together to regulate the color change rate of the reversible color-changing pellet.

[0011] The first and second low thermal conductivity materials have a thermal conductivity of less than 0.05 W / m*K, and can be fumed silica, fumed titanium dioxide, or any combination of both. To further improve the ability to control the color return and color change speed, and to facilitate moisture protection of the reversible color-changing pellet core, the first and second low thermal conductivity materials are more preferably those with a thermal conductivity of 20-400 μm. 2 Hydrophobic fumed silica or fumed titanium dioxide with a specific surface area of ​​150-400 m² / g 2 / g of hydrophobic fumed silica. The first and second low thermal conductivity materials may be the same or different.

[0012] The medium thermal conductivity material has a thermal conductivity of 0.1-1.0 W / m*K, and it also assists in regulating the color return rate and promotes pellet formation. It can be chitosan, sucrose, starch, cellulose, or any combination thereof. Chitosan is preferred as the medium thermal conductivity material, as it improves pellet formation performance while meeting the requirements of medium thermal conductivity.

[0013] Talc has a thermal conductivity of 0.1-1.0 W / m*K. In addition to meeting the requirements of medium thermal conductivity, it can also improve the roundness of the core layer of the pellet and enhance the fluidity and other properties during the processing of the core layer, thereby improving the roundness qualification rate of reversible color-changing pellets.

[0014] The thermal conductivity of the first and second high thermal conductivity materials is 100-300 W / m*K, and they can be nano-boron nitride, nano-aluminum nitride, or any combination of both. The first and second high thermal conductivity materials can be the same or different.

[0015] The primary function of the first adhesive is to fully bond the various raw materials in the core layer together into a spherical shape and to enhance the strength of the core layer. It can be carboxymethyl cellulose, carboxymethyl starch, or any combination of both. Carboxymethyl cellulose has stronger adhesion and better stability, which is beneficial for improving the strength and stability of the core; therefore, the first adhesive is preferably carboxymethyl cellulose. Furthermore, if the amount of the first adhesive is less than 0.1 parts by weight, the resulting core layer is prone to powdering and increased brittleness; if it exceeds 1 part by weight, the core layer has relatively high strength but is not easy to form into spheres, affecting the roundness of the core layer and consequently impacting the roundness qualification rate of the reversible color-changing core.

[0016] The second adhesive can fully bond the various raw materials in the core shell layer together to form a spherical shape and improve the strength of the reversible color-changing core. It can be polyvinylpyrrolidone (PVP), polyvinyl alcohol 0588 (PVA 0588), or any combination of both. PVP has better stability and the least impact on pigment color. The first adhesive is preferably polyvinylpyrrolidone K12 type (PVP K12). Furthermore, if the amount of the second adhesive is less than 0.1 parts by weight, the resulting core shell layer is prone to powdering and increased brittleness; if it exceeds 1 part by weight, the core shell layer has higher strength but is not easy to spherize, affecting the roundness qualification rate of the core layer and significantly impacting the pigment color.

[0017] The thermochromic pigment is an existing type, including heat-decolorizing and heat-developing types. The heat-decolorizing type exhibits color at low temperatures; when the temperature rises to the color-changing temperature, the pigment changes from colored to colorless. The heat-developing type does not show color at low temperatures; when the temperature rises to the color-changing temperature, the pigment changes from colorless to colored. To enable the reversible color-changing pellet core to be used in cigarette filters and to control the reversible color-changing speed, the color-changing temperature of both the heat-decolorizing and heat-developing thermochromic pigments is 30-50℃. To improve the sensitivity of the reversible color-changing pellet core to color change and color return with smoke, the color-changing temperature of the thermochromic pigment is preferably 35-45℃.

[0018] To facilitate the placement of the reversible color-changing pellet core in the transparent cavity of the cigarette filter rod, the particle size of the reversible color-changing pellet core is preferably 10-100 mesh. In particular, when the particle size of the reversible color-changing pellet core is 12-25 mesh, the visual observation effect in the transparent cavity of the cigarette filter rod is better.

[0019] The reversible color-changing core can also be loaded with functional ingredients, including flavorings, humectants, or any combination of both, which give it flavor-enhancing and humectant effects, thereby improving the characteristics and quality of cigarette products.

[0020] The main reason why the reversible color-changing pellet core provided by the present invention can achieve reversible color-changing speed control is that: (1) The pellet core shell is composed of thermochromic pigment, adhesive, high thermal conductivity material and low thermal conductivity material; when cigarette smoke passes through the pellet core shell, in addition to the smoke temperature, its color-changing speed is directly related to the thermal conductivity of the pellet core shell. By changing the ratio and amount of high thermal conductivity material and low thermal conductivity material, pellet core shells with different thermal conductivity can be obtained, thereby achieving the control of color-changing speed; (2) The pellet core core is composed of low, medium and high thermal conductivity materials and adhesive. When the cigarette is finished smoking, as the pellet core temperature decreases, the color of the pellet core shell will gradually change color. Its color change speed is directly related to the thermal conductivity of the pellet core core. By changing the amount of several components, the thermal conductivity of the pellet core core can be controlled, thereby achieving the control of color change speed.

[0021] Therefore, the above-mentioned reversible color-changing pellet core achieves controllable color change and color return speed through the synergistic effect between the components in the pellet core core layer formula, the synergistic effect between the components in the pellet core shell layer formula, and the synergistic effect between the pellet core core layer and the pellet core shell layer. Moreover, it has a high roundness qualification rate and low brittleness.

[0022] A method for preparing the above-mentioned reversible color-changing pellet core employs existing core-shell structure preparation methods. This preparation method may include the following steps:

[0023] (1) Preparation of pellet core layer

[0024] First, the components of the above-mentioned core layer are uniformly mixed with water, and then the core layer is formed into a predetermined shape; for example, the core layer is formed into a circle using the existing extrusion spheroidization method. Specifically, 10-98 parts of a first low thermal conductivity material, 1-50 parts of a medium thermal conductivity material, 1-50 parts of talc powder, 0-0.5 parts of a first high thermal conductivity material, 0.1-1 parts of a first binder, and 100-200 parts of water are mixed evenly, and then the core layer is formed using the extrusion spheroidization method.

[0025] (2) Preparation of finished pellet cores

[0026] First, the components of the above-mentioned pellet core shell layer are uniformly mixed with water to prepare a coating solution; then, the coating solution is used to coat the pellet core layer with the coating solution to form a pellet core shell layer, thereby obtaining the reversible color-changing pellet core. Specifically, 1-10 parts of thermochromic pigment, 1-5 parts of a second high thermal conductivity material, 0-5 parts of a second low thermal conductivity material, 0.1-1 parts of a second binder, and 50-100 parts of water are mixed uniformly to prepare the coating solution; then, the coating solution is used to coat the pellet core layer with the coating solution to form a pellet core shell layer, thereby obtaining the finished reversible color-changing pellet core.

[0027] Furthermore, functional ingredients such as fragrances and moisturizers can be sprayed onto the core shell using methods such as spraying to obtain a reversible color-changing core loaded with functional ingredients.

[0028] The method for preparing the reversible color-changing core provided by this invention is simple, easy to operate, and can be industrialized. Furthermore, the reversible color-changing core obtained by the above method has the characteristics of controllable color-changing and color-returning speed, low brittleness, and high roundness qualification rate, which can meet the different application processing needs of cigarette filter rods.

[0029] This invention also provides an application of the above-mentioned reversible color-changing pellet core in cigarettes. The cigarette includes a filter rod with a transparent cavity, and the reversible color-changing pellet core is filled in the transparent cavity. To ensure visual effect, the amount of the reversible color-changing pellet core added to the transparent cavity is 10-60 mg / cigarette, more preferably 20-50 mg / cigarette.

[0030] Since the reversible color-changing core can achieve controllable color change and color return speed, it can meet different consumption habits and improve the cigarette consumption experience. Attached Figure Description

[0031] Figure 1 This is a photograph of the reversible color-changing pill provided in Embodiment 1 of the present invention at room temperature. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0033] Unless otherwise specified, all terms used in this invention are commonly used in the relevant field. Raw materials, equipment, preparation processes, testing methods, etc., used in the embodiments, unless otherwise specified, are all prior art in the relevant field. The thermochromic pigments used in the following embodiments were all purchased from Dongguan Biansefeng New Materials Co., Ltd.; the fumed silica used in the following embodiments had a surface area of ​​200-250 m². 2 / g of hydrophobic fumed silica, and fumed titanium dioxide with a surface area of ​​40-50m². 2 / g of hydrophobic vapor phase titanium dioxide.

[0034] Examples 1-10: Reversible color-changing pills and their preparation methods

[0035] Examples 1-10 of this invention each provide a reversible color-changing pellet with a particle size of 12-25 mesh, comprising a core layer and a shell layer, wherein the mass ratio of the core layer to the shell layer and the raw materials of the core layer and the shell layer are shown in Table 1 and Table 2. In Table 1, "core-shell mass ratio" refers to the mass ratio of the core layer to the shell layer.

[0036] Table 1. Composition of raw materials by mass fraction of pellet core layer

[0037]

[0038]

[0039] Table 2. Composition of Raw Material Mass Parts for Pellet Core Shell Layer

[0040]

[0041] The embodiments of the present invention also provide a method for preparing the above-mentioned reversible color-changing pellet, comprising: (1) preparation of the pellet core layer, wherein the raw materials for the pellet core layer are uniformly mixed first, and then the pellet core layer is prepared by extrusion spheronization method; (2) preparation of the pellet shell layer, wherein the raw materials for the pellet shell layer are uniformly mixed first to obtain a coating liquid, and then the coating liquid is coated on the pellet core layer by a coating machine to form a pellet shell layer, thereby obtaining the finished reversible color-changing pellet core. A photograph of the reversible color-changing pellet core obtained in Example 1 is shown below. Figure 1 As shown.

[0042] Example 9

[0043] This embodiment provides a reversible color-changing core with aroma-enhancing function. The main difference between this embodiment and Embodiment 1 is that 0.5g of tobacco flavoring is sprayed onto 100g of the reversible color-changing core provided in Embodiment 1 using a spray method. After drying, a reversible color-changing core with aroma-enhancing function is obtained.

[0044] Example 10

[0045] This embodiment provides a reversible color-changing pellet core with a moisturizing function. The main difference between this embodiment and Embodiment 5 is that 1g of propylene glycol is sprayed onto 100g of the reversible color-changing pellet core provided in Embodiment 5 using a spray method, and after drying, a reversible color-changing pellet core with a moisturizing function is obtained.

[0046] Comparative Example 1

[0047] Based on Example 1, the amount of carboxymethyl cellulose in the core layer of the pellet was increased to 1.1 parts, while other conditions remained unchanged.

[0048] Comparative Example 2

[0049] Based on Example 4, the amount of PVP K12 in the pellet core shell was reduced to 0.08 parts, while other conditions remained unchanged.

[0050] Comparative Example 3

[0051] Based on Example 6, the talc powder in the core layer of the pellet was replaced with an equal weight of gypsum powder, while other conditions remained unchanged.

[0052] Comparative Example 4

[0053] Based on Example 6, the amount of boron nanonitride in the core layer of the pellet was increased to 0.6 parts, while other conditions remained unchanged.

[0054] Comparative Example 5

[0055] Based on Example 6, the amount of fumed silica in the pellet core shell was increased to 5.5 parts, while other conditions remained unchanged.

[0056] Performance verification

[0057] The brittleness and roundness of the reversible color-changing pellet cores provided in Examples 1-10 and Comparative Examples 1-5 of the present invention were tested, and the test results are shown in Table 3.

[0058] Friability: Friability of reversible color-changing pellets reflects their resistance to wear and vibration, and is one of their important characteristics. It not only affects the coating quality but also has a significant impact on pellet transportation and subsequent applications. Low friability indicates good coating quality and less powder formation, thus facilitating transportation and subsequent applications and reducing transportation and application difficulties. Considering the general industrial requirements for the friability of existing pellet products and the application of the reversible color-changing pellets provided by this invention in cigarette filter rods, a friability of <0.8% is considered acceptable for reversible color-changing pellet products.

[0059] The friability of reversible color-changing pellet cores was tested using a friability tester. The test method was as follows: the fine powder adhering to the surface of the reversible color-changing pellet core was brushed off, weighed, and placed in the drum of the friability tester. After the drum rotated at a speed of 25 r / min for 4 minutes, the reversible color-changing pellet core was removed and weighed, and the friability was calculated. Friability = (mass of reversible color-changing pellet core before test - mass of reversible color-changing pellet core after test) / mass of reversible color-changing pellet core before test × 100%.

[0060] Roundness pass rate: The roundness of the pellet core is one of its important characteristics, reflecting the quality of reversible color-changing pellet core formation. The roundness of the pellet core directly affects the deposition and formation of surface materials on the pellet core surface, thus affecting the coating quality and consequently the color-changing, aroma-enhancing, and moisture-retaining functional properties of the reversible color-changing pellet core. High roundness and uniform size and shape of the pellet core are ideal conditions for preparing reversible color-changing pellet cores.

[0061] The method for determining the roundness of reversible color-changing pellet cores is as follows: Under a microscope, measure the minimum diameter and the maximum diameter of the reversible color-changing pellet cores. The closer the ratio of the minimum diameter to the maximum diameter is to 1, the better the roundness. Usually, a ratio greater than 0.8 is considered acceptable. The roundness pass rate = (number of particles with a minimum diameter to maximum diameter ratio greater than 0.8) / (total number of particles sampled) × 100%.

[0062] Table 3 Performance Verification of Reversible Color-Changing Pellet Cores

[0063]

[0064]

[0065] As can be seen from Table 3, the roundness qualification rate of the reversible color-changing pellet cores provided in Examples 3 and 6 is 66% and 75%, respectively. This is mainly because, compared with other medium-temperature thermal conductivity materials, chitosan also has the effect of promoting the sphericity of the pellet core layer, which is beneficial to improving the roundness of the reversible color-changing pellet core.

[0066] The roundness qualification rate of the reversible color-changing pellet core provided in Comparative Example 1 was 58%, which was much lower than the 95% roundness qualification rate of the pellet core in Example 1. This is mainly because as the amount of adhesive used in the pellet core core layer increases, the viscosity of the pellet core core layer increases and the plasticity decreases during the molding process, resulting in a lower roundness qualification rate.

[0067] The reversible color-changing pellet core provided in Comparative Example 2 had a friability of 1.3%, which is a substandard product; this is higher than the 0.61% of Example 4, which is a qualified product. This is mainly because as the amount of adhesive used in the pellet core shell decreases, the bonding effect of the pellet core shell weakens, making it easier to shed powder and increasing friability.

[0068] The roundness qualification rate of the reversible color-changing pellet core provided in Comparative Example 3 was 65%, which was less than the 75% roundness qualification rate of the pellet core in Example 6. This is mainly because talc not only has the properties of a medium thermal conductivity material, but also improves the material fluidity and promotes the formation of pellets, thereby effectively improving the roundness of the reversible color-changing pellet core.

[0069] Therefore, the reversible color-changing pellet core provided in this embodiment of the invention, through the synergistic effect of controlling the mass ratio of the pellet core layer and the pellet core shell layer, the raw materials and dosage of the pellet core layer, and the raw materials and formulation of the pellet core shell layer, enables the reversible color-changing pellet core to change color and revert to its original color under different conditions depending on the different thermochromic materials contained therein. Furthermore, the synergistic effect among the raw materials in the reversible color-changing pellet core provided in this embodiment of the invention results in a friability of less than 0.8% and a roundness qualification rate exceeding 60%.

[0070] Application Examples

[0071] This application provides one cigarette containing a corresponding reversible color-changing core in each of Examples 1-10 and Comparative Examples 1-5. The cigarette is a medium-length cigarette, and its filter rod is a ternary composite filter rod with a transparent cavity. The transparent cavity is filled with the reversible color-changing cores provided in Examples 1-10 and Comparative Examples 1-5, respectively. In this application, the filter rod has dimensions of 15mm + 5mm + 10mm (tobacco end), the length of the transparent cavity is 5mm, and the amount of each reversible color-changing core added is 40mg per cigarette. Examples 1-10 and Comparative Examples 1-5 are labeled as Test Cigarettes 1-10 and Control Cigarettes 1-5, respectively, as the cigarette samples to be tested.

[0072] (1) Cigarette color change / return speed test: The color change time and return time of the reversible color-changing cartridge core were used to reflect its color change and return speed, respectively. Longer color change and return times reflected slower color change and return speeds, respectively, while shorter color change and return times reflected faster color change and return speeds, respectively. The cigarette samples used (medium-length cigarettes typically have about 6 puffs) were equilibrated for 48 hours at a temperature of (22±1)℃ and a relative humidity of (60±2)%. Then, they were sorted by weight (average weight ±0.02g) and draw resistance (average draw resistance ±49Pa) to select the test cigarettes that met the standards. The cigarette smoking test was conducted on a smoking machine according to the standard smoking conditions. The color change speed of the cartridge core was observed. After smoking, the return time of the cartridge core was timed and observed. The "color change time" was marked by the number of puffs from which the color change started, and the "return time" was the time required for the cartridge core to return to its original color after smoking. The results are shown in Table 4.

[0073] Table 4 Results of color change and color return rates of sample cigarette cores

[0074]

[0075]

[0076] As shown in Table 4, the pellet cores in different embodiments have different color-changing speeds and color-returning speeds. Comparing test cigarettes 1 and 2, their color-changing speeds are the same, but the color-returning speed of test cigarette 1 is slightly slower. This is mainly because the thermal conductivity of fumed silica in the core layer of the pellet is slightly lower, resulting in a slightly longer color-returning time and a slightly slower color-returning speed.

[0077] The color return time of test cigarette 6 was 10 seconds, significantly longer than the 1-second color return time of control cigarette 4. This means that the color return speed of the reversible color-changing cartridge provided by control cigarette 4 was too fast, making it difficult to observe the color-changing effect. This is mainly due to the increased amount of high thermal conductivity material in the cartridge core layer, which leads to a faster temperature drop after smoking, and consequently, a shorter color return time.

[0078] Compared to test cigarette 6, the control cigarette 5 used an increased amount of fumed silica in its core shell. The color-changing time during inhalation was the sixth puff, significantly longer than the fourth puff in example 6. The color-changing speed was too slow, making it difficult to observe the effect. This is mainly due to the increased amount of low thermal conductivity material in the core shell, which slows heat transfer during inhalation, resulting in a longer color-changing time and a slower color-changing speed.

[0079] Therefore, the reversible color-changing pellet core provided by this invention changes color and returns to its original color under different conditions, thereby achieving controllable speed of color change and return of the reversible color-changing pellet core; when applied to cigarettes, it will make it easy for consumers to observe color change and return, enhancing the consumer experience.

[0080] (2) Sensory evaluation: The current standards were used to conduct sensory evaluation of the test cigarettes 1, 5 and 9-10.

[0081] Compared to test cigarette 1, which uses the reversible color-changing core provided in Example 1, test cigarette 9 uses the reversible color-changing core with aroma-enhancing function provided in Example 9, which enhances aroma and improves cigarette quality. Compared to test cigarette 5, which uses the reversible color-changing core provided in Example 5, test cigarette 10 uses the reversible color-changing core with moisture-retaining function provided in Example 10, which reduces off-flavors and irritation and improves comfort.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A reversible color-changing pellet core, characterized in that: It consists of a core layer and a shell layer in a mass ratio of 20:(1-3); The core layer of the pellet is mainly composed of the following components in parts by weight: 10-98 parts of a first low thermal conductivity material, 1-50 parts of a medium thermal conductivity material, 1-50 parts of talc powder, 0-0.5 parts of a first high thermal conductivity material, and 0.1-1 parts of a first binder; The core shell of the pellet is mainly composed of the following components in parts by weight: 1-10 parts of thermochromic pigment, 1-5 parts of second high thermal conductivity material, 0-5 parts of second low thermal conductivity material, and 0.1-1 parts of second adhesive. Wherein, the thermal conductivity of the first low thermal conductivity material and the second low thermal conductivity material is less than 0.05 W / m*K, the thermal conductivity of the medium thermal conductivity material is 0.1-1.0 W / m*K, and the thermal conductivity of the first high thermal conductivity material and the second high thermal conductivity material is 100-300 W / m*K.

2. The reversible color-changing pellet core according to claim 1, characterized in that: The reversible color-changing pellet core has a particle size of 10-100 mesh.

3. The reversible color-changing pellet core according to claim 2, characterized in that: The reversible color-changing pellet core has a particle size of 12-25 mesh.

4. The reversible color-changing pellet core according to claim 1, characterized in that: The first and second low thermal conductivity materials are fumed silica, fumed titanium dioxide, or any combination of the two.

5. The reversible color-changing pellet core according to claim 4, characterized in that: The first and second low thermal conductivity materials have a thermal conductivity of 20-400 μm. 2 Hydrophobic fumed silica or fumed titanium dioxide with a specific surface area of ​​ / g.

6. The reversible color-changing pellet core according to any one of claims 1-5, characterized in that: The material with medium thermal conductivity is chitosan, sucrose, starch, or cellulose, or any combination thereof.

7. The reversible color-changing pellet core according to any one of claims 1-5, characterized in that: The first high thermal conductivity material and the second high thermal conductivity material are nano boron nitride, nano aluminum nitride, or any combination of the two.

8. The reversible color-changing pellet core according to any one of claims 1-5, characterized in that: The first adhesive is carboxymethyl cellulose, carboxymethyl starch, or any combination thereof.

9. The reversible color-changing pellet core according to any one of claims 1-5, characterized in that: The second adhesive is polyvinylpyrrolidone, polyvinyl alcohol 0588, or any combination of the two.

10. The reversible color-changing pellet core according to claim 9, characterized in that: The second adhesive is polyvinylpyrrolidone K12 type.

11. The reversible color-changing pellet core according to any one of claims 1-5 or claim 10, characterized in that: The thermochromic pigment is either a heat-decolorizing thermochromic material or a heat-generating thermochromic material.

12. The reversible color-changing pellet core according to claim 11, characterized in that: The color-changing temperature of the thermochromic pigments is 30-50℃.

13. The reversible color-changing pellet core according to claim 12, characterized in that: The color-changing temperature of the thermochromic pigment is 35-45℃.

14. The reversible color-changing pellet core according to any one of claims 1-5, or claim 10, or claim 12, or claim 13, characterized in that: The core shell of the pellet also carries functional ingredients, which include fragrances, humectants, or any combination of both.

15. A method for preparing the reversible color-changing pellet core according to claim 1, comprising the following steps: Preparation of the core layer: First, the components of the core layer are uniformly mixed with water, and then the core layer of the predetermined shape is formed. Preparation of finished pellet core: First, the components of the pellet core shell are uniformly mixed with water to obtain a coating solution; then, the coating solution is coated onto the pellet core layer using a coating machine to form the pellet core shell layer, thus obtaining the reversible color-changing pellet core.

16. The preparation method according to claim 15, characterized in that: It also includes using a spraying method to spray functional components onto the shell layer of the pellet core to obtain a reversible color-changing pellet core loaded with the functional components; wherein, the functional components include fragrances, humectants, or any combination of both.

17. The use of the reversible color-changing pellet core according to any one of claims 1-14 in cigarettes.

18. The application according to claim 17, characterized in that: The cigarette includes a filter rod with a transparent cavity, and the reversible color-changing core is filled in the transparent cavity.

19. The application according to claim 18, characterized in that: The amount of the reversible color-changing pellet added to the transparent cavity is 10-60 mg per cigarette.

20. The application according to claim 19, characterized in that: The amount of the reversible color-changing pellet added to the transparent cavity is 20-50 mg per cigarette.

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