A heated cigarette core material and preparation method thereof

Abstract

The present invention relates to the technical field of tobacco products, and discloses a heated cigarette core material and a preparation method thereof. The present invention prepares a self-heating organic porous adsorbent, sequentially loads flavors and spices, tobacco raw materials, etc. on the porous adsorbent for granulation, and mixes wax raw materials therein, thereby obtaining a core material that can quickly release fragrance at a relatively low temperature, and the core material has the characteristics of a high fragrance loading rate.

Description

Technical Field

[0001] The invention relates to the technical field of tobacco products, and in particular to a heated cigarette core material and a preparation method thereof. Background Art

[0002] In recent years, there have been more and more reports on research on heated cigarettes in China. As the most important component of heated cigarettes, the research on heated cigarette core materials has attracted much attention.

[0003] Heated cigarettes are different from traditional cigarettes in that they burn at high temperatures. They rely on high-temperature heat sources to heat the air flowing through them, and use hot air distillation to atomize the tobacco filling after the heat source. The maximum temperature is generally not higher than 400°C. Through the heat conduction function of the heat source, the smoke inhaled by consumers meets their smoking habits and sensory needs, reducing the possibility of harmful substances produced by high-temperature combustion of cigarettes, thereby reducing the harm of cigarettes.

[0004] However, since heated cigarettes are heated at low temperatures, this type of tobacco requires that the flavors be released quickly at relatively low temperatures, but existing heated cigarette core materials often have difficulty meeting this requirement.

[0005] In the prior art, as disclosed in Chinese patent CN110477436A, a preparation method and application of slow-release particles of tobacco flavors are disclosed. The invention is based on the existing tobacco flavor raw materials, by fusing tobacco flavors into the solid phase, forming a moderate release of aroma substances, thereby stabilizing the adverse stimulation brought by the whole flavor, alleviating the difference of the front-heavy and back-light brought by the sensory system process, and the prepared slow release can better volatilize the aroma of tobacco flavors smoothly and gently, and is suitable for use in different tobacco products. However, the fixed phase carrier used to load spices has poor thermal conductivity, which can cause spices to be unable to be completely released at working temperature when used as a carrier of spices, and the fragrance release rate is relatively slow, resulting in the smoke fragrance not being strong enough.

[0006] Therefore, in order to solve the problem of achieving rapid release of heated cigarette flavors at lower temperatures, this research team aims to develop a new method for preparing heated cigarette core materials to achieve rapid release of tobacco flavors under low-temperature heating conditions. Summary of the invention

[0007] In order to solve the technical problem of achieving rapid release of heated cigarette flavors at a relatively low temperature, the present invention provides a heated cigarette core material and a preparation method thereof. The present invention prepares a self-heating organic porous adsorbent, sequentially loads flavors and spices, tobacco raw materials, etc. on the porous adsorbent for granulation, and mixes wax raw materials therein to obtain a core material capable of rapidly releasing flavors, and the core material has the characteristics of a high flavor loading rate.

[0008] The specific technical scheme of the present invention is:

[0009] The present invention provides a method for preparing a heated cigarette core material, comprising the following steps:

[0010] (1) Preparing a heat-generating adsorbent skeleton: under heating conditions, adding a magnetic substance, a crosslinking agent and an initiator to an N-isopropylacrylamide monomer solution while stirring to initiate prepolymerization, and continuing to stir during the polymerization process to obtain an N-isopropylacrylamide oligomer;

[0011] (2) preparing a heat-generating adsorbent: adding a saturated polyvinyl alcohol solution to the N-isopropylacrylamide oligomer obtained in (1), and adding a cross-linking agent, stirring to dissolve, and then adding an initiator to react, cooling, and washing to obtain a porous heat-generating adsorbent;

[0012] (3) preparing a fragrance-generating content: adding flavors and fragrances and smoke-generating agents to the exothermic adsorbent obtained in step (2), stirring, and freeze-drying to obtain a fragrance-generating content;

[0013] (4) Preparing a cigarette core material: mixing the aroma content obtained in step (3) with tobacco raw materials and waxy materials to obtain the heated cigarette core material.

[0014] In the method for preparing the heated cigarette core material provided by the present invention, specifically:

[0015] First, in step (1), a preliminary structure of poly (N-isopropylacrylamide) is formed, which is a copolymer with a certain degree of crosslinking. The copolymer is the preliminary skeleton of the adsorbent, and magnetic material is added during the process of forming the preliminary skeleton of the adsorbent to be embedded in the skeleton. However, the organic skeleton structure prepared in step (1) is unstable, and the magnetic material also has a tendency to escape from the adsorbent skeleton. Therefore, further, in step (2), a polyvinyl alcohol solution is added for secondary crosslinking. Under the action of the initiator, the hydrogen atoms in the hydroxyl groups of the polyvinyl alcohol are ionized to generate a large number of crosslinking points for the self-crosslinking of the polyvinyl alcohol. The three-dimensional network structure formed after the self-crosslinking of the polyvinyl alcohol and the interlacing effect between the poly (N-isopropylacrylamide) network firmly wrap the magnetic material to prepare a porous heat-generating adsorbent.

[0016] During the secondary cross-linking reaction, polyvinyl alcohol can be interspersed in the network cross-linking structure of the N-isopropylacrylamide oligomer prepolymer to play a reinforcing role. Therefore, the strength and toughness of the final organic adsorbent will be better, and the porosity of the adsorbent will be high. At the same time, during the network cross-linking process, the magnetic substance can be more firmly fixed in the adsorbent skeleton. However, this research team found that in the process of forming the adsorbent, if the N-isopropylacrylamide monomer solution and the polyvinyl alcohol solution are added to the system at the same time for direct cross-linking, the degree of hybridization in the obtained organic polymer is too high. Although it is beneficial to the fixation of the magnetic substance, the adsorption effect on flavors and fragrances and tobacco is poor. Therefore, the preparation method of the present invention chooses to cross-link the N-isopropylacrylamide monomer solution and the polyvinyl alcohol solution in steps.

[0017] Thereafter, in step (3), flavors and fragrances are added to the heat-generating adsorbent so that they are adsorbed on the heat-generating adsorbent. Since the heat-generating adsorbent prepared in steps (1) to (2) has a high porosity and a large specific surface area, the adsorption rate of the flavors and fragrances, i.e., the fragrance carrying rate, is high. Finally, in step (4), tobacco raw materials and wax materials are added to obtain a heated cigarette core material that can quickly release fragrance. The wax material can form a wax film therein, which can prevent the heated cigarette core material from losing its fragrance due to environmental factors during the shelf life. At the same time, the wax material can quickly melt when heated and smoked, thereby quickly releasing the fragrance.

[0018] The heated cigarette heats the cigarette core material by inserting a heating element into the cigarette stick, and is provided with a magnetic induction unit. When the heated cigarette core material prepared by the above steps (1) to (4) provided by the present invention is applied to the heated cigarette for smoking, the magnetic induction unit heats the magnetic substance in the heating adsorbent, thereby accelerating the release of the flavor substance, so that the flavor can be released quickly at a lower temperature. Furthermore, the magnetic field strength can be adjusted by the magnetic induction unit to control the heat generation of the magnetic substance, so as to achieve the purpose of regulating the intensity and rate of flavor release.

[0019] As a preferred embodiment of the above technical solution of the present invention, in step (1), the concentration of the N-isopropylacrylamide monomer solution is 50-60 wt %.

[0020] As a preferred embodiment of the above technical solution of the present invention, in step (1), the magnetic material is one or more of carbon steel powder, iron powder, and nickel-iron alloy powder.

[0021] As a preferred embodiment of the above technical solution of the present invention, the mass ratio of N-isopropylacrylamide monomer to magnetic substance is 40-50:1.

[0022] As a preferred embodiment of the above technical solution of the present invention, in step (2), the reaction temperature is 70 to 85° C., and the reaction time is 2 to 4 hours.

[0023] The interaction between the polyvinyl alcohol molecular chain and the poly (N-isopropylacrylamide) network is mainly physical entanglement and hydrogen bonding. In addition, when synthesizing the poly (N-isopropylacrylamide) / poly (Vinyl alcohol) interpenetrating network adsorbent, due to the use of a saturated solution of polyvinyl alcohol, when the microenvironment of the system changes, polyvinyl alcohol crystals will be precipitated. The precipitated polyvinyl alcohol and the poly (N-isopropylacrylamide) matrix are combined by a large number of hydrogen bonds. One of the functions of adding magnetic substances is to ultimately give the prepared cigarette core material self-heating properties. Another function is to prevent excessive bonding between polyvinyl alcohol and the poly (N-isopropylacrylamide) matrix in this process, so that a porous network interpenetrating adsorbent cannot be obtained, thereby preventing the adsorbent from being too dense and failing to meet the ideal fragrance-carrying requirements.

[0024] As a preferred embodiment of the above technical solution of the present invention, the Mn of the polyvinyl alcohol in step (2) is 80,000-130,000, and the alcoholysis rate is >99%.

[0025] As a preferred embodiment of the above technical solution of the present invention, the mass ratio of the N-isopropylacrylamide monomer to the polyvinyl alcohol is 5:0.16-0.18.

[0026] The use of polyvinyl alcohol with a higher viscosity is beneficial to the interaction with the poly (N-isopropylacrylamide) network.

[0027] As a preferred embodiment of the above technical solution of the present invention, in step (1) and step (2), the cross-linking agent is dimethyl imine ester.

[0028] When preparing the heat-generating adsorbent, a cross-linking agent, dimethyl imine ester, is added to ensure that the skeleton of the adsorbent has a certain degree of chemical bond cross-linking and a certain strength. The reaction time should not be too long or too short. If the reaction time is too short, the degree of polymerization is not high and the strength of the gel carrier framework is insufficient. The reaction time should not be too long either. If the reaction time is too long, the polymer will have too high a degree of cross-linking and it will be impossible to form a stock solution to cool and obtain a heat-generating adsorbent. Alternatively, although the adsorbent is cooled and solidified in time, it will be too hard and too dense to carry fragrance.

[0029] As a preferred embodiment of the above technical solution of the present invention, in step (1), the temperature of the heating condition is 75-85°C.

[0030] As a preferred embodiment of the above technical solution of the present invention, in step (1) and step (2), the initiator is potassium persulfate.

[0031] As a preferred embodiment of the above technical solution of the present invention, the waxy material is one or more of soybean wax, rice bran wax, sugarcane wax, coconut wax, candelilla wax and palm wax.

[0032] The selection requirements for wax materials are that the wax materials need to have a natural smell, be coordinated with the tobacco flavor, and have the characteristics of low melting temperature. Among them, the melting point of soybean wax is 52°C, the melting point of rice bran wax is 60-85°C, the melting point of sugarcane wax is 70-84°C, the melting point of coconut wax is 40-45°C, the melting point of candelilla wax is 68-73°C, and the melting point of palm wax is 81-86°C.

[0033] As a preferred embodiment of the above technical solution of the present invention, the smoke generating agent in step (3) is selected from propylene glycol and glycerol.

[0034] As a preferred embodiment of the above technical solution of the present invention, the flavors and fragrances in step (4) are selected from tobacco, floral, and fruity essential oils. Specifically, they can be selected from tobacco, lemon, mint, coffee, strawberry, blueberry, pineapple, peach, apple, orange, watermelon, red dates, dark plum, and olive flavors and fragrances, but are not limited thereto.

[0035] Compared with the prior art, the present invention has the following technical effects:

[0036] The heated cigarette core material prepared by the preparation method provided by the present invention can reasonably use the magnetic induction unit provided on the heating element of the cigarette, so that the core material has self-heating performance when smoking. Based on this, the heated cigarette core material prepared by the present invention can well overcome the problem of slow and incomplete release of fragrances due to the poor thermal conductivity of the carrier itself when using polymer materials as carriers to load fragrances in the prior art. Due to magnetic induction heating, the heated cigarette core material prepared by the present invention can start from the inside of the heating adsorbent, heat from the inside to the outside, and perform a self-heating process of the core material. In combination with the external heating of the smoking device, the flavors and fragrances can be quickly released at a lower temperature, with a strong fragrance and complete fragrance release. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the embodiments.

[0038] Example 1

[0039] (1) Preparation of saturated polyvinyl alcohol solution: 160 mg of polyvinyl alcohol was added to 150 mL of water, heated to 85° C. in a water bath, and stirred for 4 h until the polyvinyl alcohol no longer dissolved, thereby obtaining a saturated polyvinyl alcohol solution.

[0040] (2) Preparation of a heat-generating adsorbent skeleton: 45 g of N-isopropylacrylamide monomer was added to pure water to obtain a 50 wt% N-isopropylacrylamide monomer solution, and then 1 g of nickel-iron alloy powder, 0.4 g of dimethylimide and 10 g of initiator potassium persulfate were added under stirring at 80° C. to initiate prepolymerization. Stirring was continued during the polymerization process to obtain an N-isopropylacrylamide oligomer.

[0041] (3) Preparation of exothermic adsorbent: When the viscosity of N-isopropylacrylamide oligomer increases, quickly add it to (1) to obtain a saturated polyvinyl alcohol solution, and add 0.2 g of dimethyl imine ester. After stirring and dissolving at 70°C, add 2 g of initiator potassium persulfate, react for 3 hours, cool, and wash with ethanol twice to obtain a exothermic adsorbent.

[0042] (4) Preparation of aroma content: Add 10 g of black plum essence and 500 g of propylene glycol to the exothermic adsorbent obtained in (3), stir and soak for 6 h, and then freeze-dry to obtain the aroma content.

[0043] (5) Preparing a core material: The aroma content obtained in step (4) is mixed with 20 g of K326 tobacco extract and 8 g of coconut wax, and the mixture is granulated by screw extrusion and passed through a 20-mesh sieve to obtain a core material, i.e., the core material for heated cigarettes.

[0044] Example 2

[0045] (1) Preparation of saturated polyvinyl alcohol solution: 170 mg of polyvinyl alcohol was added to 150 mL of water, heated to 85° C. in a water bath, and stirred for 4 h until the polyvinyl alcohol no longer dissolved, thereby obtaining a saturated polyvinyl alcohol solution.

[0046] (2) Preparation of a heat-generating adsorbent skeleton: 40 g of N-isopropylacrylamide monomer was added into pure water to obtain a 55 wt% N-isopropylacrylamide monomer solution, and then 1 g of iron powder, 0.4 g of dimethylimide and 10 g of initiator potassium persulfate were added under stirring at 75° C. to initiate prepolymerization. Stirring was continued during the polymerization process to obtain an N-isopropylacrylamide oligomer.

[0047] (3) Preparation of exothermic adsorbent: When the viscosity of N-isopropylacrylamide oligomer increases, quickly add it to (1) to obtain a saturated polyvinyl alcohol solution, and add 0.2 g of dimethyl imine ester. After stirring and dissolving at 80°C, add 2 g of initiator potassium persulfate, react for 2 h, cool, and wash twice with ethanol to obtain an exothermic adsorbent.

[0048] (4) Preparation of aroma content: Add 10 g of peppermint essential oil and 500 g of propylene glycol to the exothermic adsorbent obtained in (3), stir and soak for 6 h, and then freeze-dry to obtain the aroma content.

[0049] (5) Preparing a core material: The aroma content obtained in step (4) is mixed with 20 g of K326 tobacco extract and 8 g of soybean wax, and the mixture is granulated by screw extrusion and passed through a 40-mesh sieve to obtain a core material, i.e., the core material of the heated cigarette.

[0050] Example 3

[0051] (1) Preparation of saturated polyvinyl alcohol solution: 180 mg of polyvinyl alcohol was added to 150 mL of water, heated in a water bath to 85° C., and stirred for 4 h until the polyvinyl alcohol no longer dissolved, thereby obtaining a saturated polyvinyl alcohol solution.

[0052] (2) Preparation of a heat-generating adsorbent skeleton: 50 g of N-isopropylacrylamide monomer was added into pure water to obtain a 60 wt% N-isopropylacrylamide monomer solution. Then, 1 g of carbon steel powder, 0.4 g of dimethylimide and 10 g of initiator potassium persulfate were added at 85°C while stirring to initiate prepolymerization. Stirring was continued during the polymerization process to obtain an N-isopropylacrylamide oligomer.

[0053] (3) Preparation of exothermic adsorbent: When the viscosity of N-isopropylacrylamide oligomer increases, quickly add it to (1) to obtain a saturated polyvinyl alcohol solution, and add 0.2 g of dimethyl imine ester. After stirring and dissolving at 85°C, add 2 g of initiator potassium persulfate, react for 4 hours, cool, and wash twice with ethanol to obtain an exothermic adsorbent.

[0054] (4) Preparation of aroma content: Add 10 g of orchid essential oil and 500 g of propylene glycol to the exothermic adsorbent obtained in (3), stir and soak for 6 hours, and then freeze-dry to obtain the aroma content.

[0055] (5) Preparing a core material: The aroma content obtained in step (4) is mixed with 20 g of K326 tobacco extract and 8 g of palm wax, and the mixture is granulated by screw extrusion and passed through a 20-mesh sieve to obtain a core material, i.e., the core material for heated cigarettes.

[0056] Comparative Example 1 (the main difference from Example 1 is that polyvinyl alcohol is not added for network crosslinking)

[0057] (1) Preparation of a heat-generating adsorbent skeleton: 45 g of N-isopropylacrylamide monomer was added to pure water to obtain a 50 wt% N-isopropylacrylamide monomer solution, and then 1 g of nickel-iron alloy powder, 0.4 g of dimethylimide and 10 g of initiator potassium persulfate were added under stirring at 80°C to initiate prepolymerization. Stirring was continued during the polymerization process. The polymerization reaction lasted for 3 hours, cooled, and washed twice with ethanol to obtain a heat-generating adsorbent.

[0058] (2) Preparation of aroma content: Add 10 g of black plum essence and 500 g of propylene glycol to the exothermic adsorbent obtained in (1), stir and soak for 6 h, and then freeze-dry to obtain the aroma content.

[0059] (3) Preparing a core material: The aroma content obtained in step (4) is mixed with 20 g of K326 tobacco extract and 8 g of coconut wax, and the mixture is granulated by screw extrusion and passed through a 20-mesh sieve to obtain a core material, i.e., the heated cigarette core material.

[0060] Comparative Example 2 (the main difference from Example 1 is that the N-isopropylacrylamide monomer solution is directly mixed with the polyvinyl alcohol solution for cross-linking)

[0061] (1) Preparation of saturated polyvinyl alcohol solution: 160 mg of polyvinyl alcohol was added to 150 mL of water, heated to 85° C. in a water bath, and stirred for 4 h until the polyvinyl alcohol no longer dissolved, thereby obtaining a saturated polyvinyl alcohol solution.

[0062] (2) Preparation of a heat-generating adsorbent skeleton: 45 g of N-isopropylacrylamide monomer was added to pure water to obtain a 50 wt% N-isopropylacrylamide monomer solution, which was quickly added to (1) to obtain a saturated polyvinyl alcohol solution. Then, 1 g of nickel-iron alloy powder, 0.6 g of dimethylimide and 12 g of initiator potassium persulfate were added at 80°C while stirring to initiate prepolymerization. Stirring was continued during the polymerization process. The polymerization reaction lasted for 3 hours, cooled, and washed twice with ethanol to obtain a heat-generating adsorbent.

[0063] (3) Preparation of aroma content: Add 10 g of black plum essence and 500 g of propylene glycol to the exothermic adsorbent obtained in (2), stir and soak for 6 h, and then freeze-dry to obtain the aroma content.

[0064] (4) Preparing a core material: The aroma content obtained in step (3) is mixed with 20 g of K326 tobacco extract and 8 g of coconut wax, and the mixture is granulated by screw extrusion and passed through a 20-mesh sieve to obtain a core material, i.e., the heated cigarette core material.

[0065] Comparative Example 3 (the main difference from Example 1 is that the adsorbent does not carry magnetic material)

[0066] (1) Preparation of saturated polyvinyl alcohol solution: 160 mg of polyvinyl alcohol was added to 150 mL of water, heated to 85° C. in a water bath, and stirred for 4 h until the polyvinyl alcohol no longer dissolved, thereby obtaining a saturated polyvinyl alcohol solution.

[0067] (2) Preparation of adsorber skeleton: 45 g of N-isopropylacrylamide monomer was added into pure water to obtain a 50 wt% N-isopropylacrylamide monomer solution, and then 0.4 g of dimethylimide and 10 g of initiator potassium persulfate were added under stirring at 80° C. to initiate prepolymerization, and stirring was continued during the polymerization process to obtain N-isopropylacrylamide oligomer.

[0068] (3) Preparation of adsorbent: When the viscosity of N-isopropylacrylamide oligomer increases, quickly add it to (1) to obtain a saturated polyvinyl alcohol solution, and add 0.2 g of dimethyl imine ester. After stirring and dissolving at 70°C, add 2 g of initiator potassium persulfate, react for 3 hours, cool, and wash with ethanol twice to obtain a heat-generating adsorbent.

[0069] (4) Preparation of aroma content: Add 10 g of black plum essence and 500 g of propylene glycol to the exothermic adsorbent obtained in (3), stir and soak for 6 h, and then freeze-dry to obtain the aroma content.

[0070] (5) Preparing a core material: The aroma content obtained in step (4) is mixed with 20 g of K326 tobacco extract and 8 g of coconut wax, and the mixture is granulated by screw extrusion and passed through a 20-mesh sieve to obtain a core material, i.e., the core material for heated cigarettes.

[0071] Comparative Example 4 (the main difference from Example 1 is that no coconut wax granulation is added)

[0072] (1) Preparation of saturated polyvinyl alcohol solution: 160 mg of polyvinyl alcohol was added to 150 mL of water, heated to 85° C. in a water bath, and stirred for 4 h until the polyvinyl alcohol no longer dissolved, thereby obtaining a saturated polyvinyl alcohol solution.

[0073] (2) Preparation of a heat-generating adsorbent skeleton: 45 g of N-isopropylacrylamide monomer was added to pure water to obtain a 50 wt% N-isopropylacrylamide monomer solution, and then 1 g of nickel-iron alloy powder, 0.4 g of dimethylimide and 10 g of initiator potassium persulfate were added under stirring at 80° C. to initiate prepolymerization. Stirring was continued during the polymerization process to obtain an N-isopropylacrylamide oligomer.

[0074] (3) Preparation of exothermic adsorbent: When the viscosity of N-isopropylacrylamide oligomer increases, quickly add it to (1) to obtain a saturated polyvinyl alcohol solution, and add 0.2 g of dimethyl imine ester. After stirring and dissolving at 70°C, add 2 g of initiator potassium persulfate, react for 3 hours, cool, and wash with ethanol twice to obtain a exothermic adsorbent.

[0075] (4) Preparation of aroma content: Add 10 g of black plum essence and 500 g of propylene glycol to the exothermic adsorbent obtained in (3), stir and soak for 6 h, and then freeze-dry to obtain the aroma content.

[0076] (5) Preparing a core material: The aroma content obtained in step (4) is mixed with 20 g of K326 tobacco extract, granulated by screw extrusion, and passed through a 20-mesh sieve to obtain a core material, i.e., the core material for the heated cigarette.

[0077] Performance Evaluation

[0078] The heated cigarette core materials obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were respectively filled into cigarettes, and the cigarettes were smoked using a matching electric heating smoking device, which was the smoking device product disclosed in the prior patent CN114287675A of this unit, and the smoking device had a magnetic induction unit and a heating element, specifically Example 1. Among them, the flavor aroma is the sensory evaluation test result of the quantity and quality of the flavor and fragrance, and the start time is the recorded start time of the comprehensive fruit aroma. The results are shown in Table 1.

[0079] Spices Start time / s Example 1 Rich fragrance, comfortable and long-lasting fragrance 5.1 Example 2 Rich fragrance, comfortable and long-lasting fragrance 5.0 Example 3 Rich fragrance, comfortable and long-lasting fragrance 5.9 Comparative Example 1 Light fragrance, comfortable scent 7.1 Comparative Example 2 Light fragrance, comfortable scent 7.0 Comparative Example 3 Rich fragrance, comfortable and long-lasting fragrance 13.5 Comparative Example 4 Light fragrance, comfortable scent 7.0

[0080] As can be seen from Table 1, the heated cigarette core material prepared by the preparation method provided by the present invention releases fragrance quickly, and the smell of flavors and spices can be felt within only 0.3 seconds. At the same time, the fragrance of the flavors and spices is rich and comfortable, indicating that the heated cigarette core material prepared by the present invention has a high fragrance carrying rate.

[0081] Compared with Example 1, Comparative Example 1 does not add polyvinyl alcohol for network crosslinking, and the fragrance of the flavors and fragrances felt is weak, indicating that the network crosslinking of polyethanol is beneficial to the fragrance of the adsorbent and improves the richness of the fragrance. Further analysis shows that the addition of polyvinyl alcohol for network crosslinking can increase the adsorption rate of the heat-generating adsorbent for flavors and fragrances, which should be based on the increase in contact area, that is, the network crosslinking of polyvinyl alcohol can increase the porosity of the heat-generating body and increase the surface area.

[0082] Compared with Example 1, in Comparative Example 2, the N-isopropylacrylamide monomer solution is directly mixed with the polyvinyl alcohol solution for cross-linking, and the fragrance of the flavors and spices felt is weak, indicating that the step-by-step cross-linking of the N-isopropylacrylamide monomer solution and the polyvinyl alcohol solution is beneficial to the aroma of the adsorbent and improves the richness of the aroma. Further analysis shows that directly mixing the N-isopropylacrylamide monomer solution with the polyvinyl alcohol solution for cross-linking may cause the cross-linked heat-generating adsorbent to be too dense, and the aroma of the heat-generating adsorbent is greatly reduced.

[0083] Compared with Example 1, the adsorbent in Comparative Example 3 does not contain any magnetic material, and the time when the flavors and fragrances begin to be felt is greatly delayed, indicating that loading magnetic material to make the cigarette core material self-heat from the inside out can greatly increase the aroma release rate of the material.

[0084] Compared with Example 1, Comparative Example 4 does not add coconut wax granulation, and the fragrance of the flavors and spices felt is weak, indicating that the flavors and spices in Comparative Example 4 have a certain loss, so the fragrance felt is weak. Further analysis shows that Comparative Example 4 does not add wax material, and the cigarette core material lacks a wax film to isolate the volatile substances in the cigarette core material from the air. Due to the lack of the wax film interface, the volatile substances in the cigarette core material, such as flavors and spices, are more volatile and will be greatly lost during a long period of storage.

[0085] The polyvinyl alcohol used in the above-mentioned embodiments of the present invention, i.e., the comparative examples, has an Mn of 80,000 to 130,000, and an alcoholysis rate of >99%.

[0086] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0087] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a heated cigarette core material, characterized in that: The following steps are involved: (1) Preparing a heat-generating adsorbent skeleton: under heating conditions, adding a magnetic substance, a crosslinking agent and an initiator to an N-isopropylacrylamide monomer solution while stirring to initiate prepolymerization, and continuing to stir during the polymerization process to obtain an N-isopropylacrylamide oligomer; wherein the mass ratio of the N-isopropylacrylamide monomer to the magnetic substance is 40-50:1; (2) Preparing a heat-generating adsorbent: adding a saturated polyvinyl alcohol solution to the N-isopropylacrylamide oligomer obtained in (1), and adding a cross-linking agent, stirring to dissolve, and then adding an initiator to react, cooling, and washing to obtain a heat-generating adsorbent; (3) preparing the aroma content: adding flavors and fragrances and smoke generating agents to the exothermic adsorbent obtained in (2), stirring, and freeze-drying to obtain the aroma content; (4) Preparing a core material: mixing the aroma content obtained in step (3) with tobacco raw materials and waxy materials, and molding them to obtain a core material, i.e., the core material of the heated cigarette.

2. The method for preparing a heated cigarette core material according to claim 1, characterized in that: In step (1), the heating temperature is 75-85°C.

3. The method for preparing a heated cigarette core material according to claim 1, characterized in that: In step (1), the concentration of the N-isopropylacrylamide monomer solution is 50-60 wt %.

4. The method for preparing a heated cigarette core material according to claim 1, characterized in that: In step (1), the magnetic material is one or more of carbon steel, iron, and nickel-iron alloy.

5. The method for preparing a heated cigarette core material according to claim 1, characterized in that: In step (2), the reaction temperature is 70-85° C. and the reaction time is 2-4 h.

6. The method for preparing a heated cigarette core material according to claim 1, characterized in that: The average molecular weight of the polyvinyl alcohol is 80,000-130,000.

7. A method for preparing a heated cigarette core material according to claim 1 or 6, characterized in that: The mass ratio of the N-isopropylacrylamide monomer to the polyvinyl alcohol is 5:0.16-0.

18.

8. The method for preparing a heated cigarette core material according to claim 1, characterized in that: In step (4), the wax material is one or more of soybean wax, rice bran wax, sugarcane wax, coconut wax, candelilla wax, and palm wax.

9. A heated cigarette core material prepared by the preparation method according to any one of claims 1 to 8.