Core-sheath structure fragrant line, preparation method thereof and cigarette filter stick

Abstract

The invention relates to the technical field of cigarette perfuming, in particular to a core-sheath structure perfumed thread, a preparation method thereof and a cigarette filter stick. The preparation method comprises the following steps: by taking beta-cyclodextrin as a wall material and essence as a core material, preparing beta-cyclodextrin / essence microcapsules by adopting an inclusion method; dissolving the beta-cyclodextrin / essence microcapsule and polylactic acid in a solvent to obtain a core layer spinning solution; polylactic acid is dissolved in a solvent, and a sheath spinning solution is obtained; wet spinning is adopted for coaxial spinning, the center shaft spinning solution is the core layer spinning solution, the outer shaft spinning solution is the sheath layer spinning solution, and the core-sheath structure fragrant thread is obtained. Spinning is carried out by combining microcapsule embedding with a wet spinning integrated technology, the prepared incense thread has the stable essence adding and releasing capacity, when high-temperature smoke passes through the incense thread, raspberry ketone can be released from microgaps in the wall of the microcapsule, and therefore the durability of cigarette fragrance is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of cigarette flavoring technology, and in particular to a core-sheath structure flavoring thread, its preparation method, and a cigarette filter rod. Background Technology

[0002] In traditional cigarette flavoring technology, the impregnation method is a common way to load flavoring. It involves soaking cellulose substrates, such as viscose fiber and cellulose acetate, in a flavoring solution. The flavoring is loaded onto the fiber surface and pores through physical adsorption or simple chemical bonding. After drying, it is embedded in the cigarette filter. This technology is simple and requires low equipment. It is widely used in the preparation of low-cost flavoring threads and is suitable for industrial production. For example, Chinese patent document CN106387994A discloses a cigarette filter rod containing a slow-release flavoring core thread. This scheme uses the impregnation method to load the flavoring onto the fabric fiber core thread. It does not require complicated equipment and can load a variety of flavoring components. Although the impregnation method is widely used, it has the following key technical bottlenecks, which seriously affect the persistence and stability of cigarette aroma. The following problems exist: (1) The flavoring is only adsorbed on the fiber surface and shallow pores and cannot penetrate into the fiber interior, resulting in a low effective loading rate; (2) The adsorption process is limited by the specific surface area of ​​the fiber. For example, the specific surface area of ​​viscose fiber is usually <0.5m². 2 / g, flavorings are easily lost through volatilization during the drying process; (3) impregnated flavorings are mainly physically adsorbed, and the binding structure is not stable enough. They are deactivated at high temperatures during cigarette processing (such as drying and rolling) or combustion; (4) flavoring release depends on diffusion through fiber pores, resulting in an overly strong aroma in the first few puffs and a sudden decrease in the later stages. Summary of the Invention

[0003] To solve or partially solve the problems existing in related technologies, the present invention provides a core-sheath structure fragrance thread, its preparation method, and a cigarette filter rod.

[0004] This invention provides a method for preparing a core-sheath structure incense thread, comprising:

[0005] Step a) Using β-cyclodextrin as the wall material and fragrance as the core material, β-cyclodextrin / fragrance microcapsules were prepared by inclusion method;

[0006] Step b) Dissolve the β-cyclodextrin / fragrance microcapsules and polylactic acid in a solvent to obtain a core spinning solution; dissolve the polylactic acid in a solvent to obtain a sheath spinning solution;

[0007] Step c) Coaxial spinning is performed using wet spinning, with the spinning solution for the central axis being the core layer spinning solution and the spinning solution for the outer axis being the sheath layer spinning solution, to obtain a core-sheath structure fragrance thread.

[0008] Further, in step a), the flavoring is raspberry ketone, and the β-cyclodextrin / flavoring microcapsules are β-cyclodextrin / raspberry ketone microcapsules.

[0009] Further, step a) specifically includes:

[0010] Step a1) Dissolve β-cyclodextrin in water and stir in a heated water bath to prepare a wall material solution with a concentration of 1% to 6%;

[0011] Step a2) Mix raspberry ketone with surfactant, add to deionized water, and homogenize and emulsify to form raspberry ketone emulsion; the concentration of raspberry ketone in the raspberry ketone emulsion is 5% to 15%, and the mass ratio of surfactant to raspberry ketone is 1 to 5:100.

[0012] Step a3) Add the raspberry ketone emulsion to the wall material solution and stir to emulsify. The mass ratio of raspberry ketone to β-cyclodextrin in the mixed emulsion is 1:3 to 9.

[0013] Step a4) After the emulsified solution was cooled to room temperature, it was centrifuged, washed and dried to obtain β-cyclodextrin / raspberry ketone microcapsules.

[0014] Further, in step a1), the water bath temperature is 50–70°C; and / or, in step a2), the surfactant is Span 80, the homogenization speed is 8000–10000 rpm, and the time is 2–5 min.

[0015] Further, in step a3), the stirring speed for emulsification is 500-800 rpm and the temperature is 30-60°C; and / or, in step a4), the drying is freeze drying.

[0016] Further, in step b), the solvent is dichloromethane, and the mass ratio of β-cyclodextrin / fragrance microcapsules, polylactic acid and dichloromethane in the core spinning solution is 5-15:10-25:60-90; the mass ratio of polylactic acid and dichloromethane in the sheath spinning solution is 10-15:85-90.

[0017] Further, in step c), the size of the central shaft needle is 18-20G, and the size of the outer shaft needle is 14-16G; the flow rate of the central shaft spinning solution is 0.8-1.5mL / h, and the flow rate of the outer shaft spinning solution is 2-4mL / h.

[0018] Further, in step c), the coagulation bath is an ethanol solution with a concentration of 50-100% and a temperature of 15-35°C.

[0019] The present invention also provides a core-sheath structure incense thread, which is prepared according to any one of the methods described above.

[0020] The present invention also provides a cigarette filter rod having the above-mentioned core-sheath structure fragrance thread.

[0021] The core-sheath structure incense thread and its preparation method provided by this invention can have the following beneficial effects:

[0022] 1. This method first uses β-cyclodextrin as the wall material to encapsulate the fragrance into microcapsules. Then, the microcapsules are coaxially wet-spun with polylactic acid using a blending method to construct a core-sheath structure. The core layer contains microcapsules, and the sheath layer is pure polylactic acid. When flue gas passes through, the gaps in the microcapsule walls of the core layer are heated. Under the action of β-cyclodextrin locking the fragrance molecules through van der Waals forces, the fragrance is slowly released. The dense PLA layer of the sheath layer physically blocks the rapid escape of the fragrance and slows down the release rate.

[0023] 2. Wet spinning is employed, preventing the fragrance from being heated during the spinning process and suppressing the problem of fragrance volatilization and decomposition due to heat during processing. The polylactic acid sheath layer encapsulating the fragrance microcapsule core reduces fragrance loss during daily storage. Both polylactic acid and β-cyclodextrin are biodegradable materials, meeting the green standards of the tobacco industry.

[0024] 3. This invention uses microcapsule embedding combined with wet spinning integrated technology to prepare fragrance thread with stable ability to add and release fragrance. When high-temperature smoke passes through the fragrance thread, raspberry ketone can be released from the micro gaps on the microcapsule wall, thereby ensuring the persistence of cigarette aroma.

[0025] 4. Experiments have shown that β-cyclodextrin inclusion complexation improves the retention rate of raspberry ketone at 30℃ to 95%, which is 47% higher than direct addition. During the inhalation process, the release rate accounts for more than 50% in the first 3 puffs, and the release rate remains stable in the last 4 puffs, with a significant improvement in aroma uniformity.

[0026] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0027] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts.

[0028] Figure 1 These are the encapsulation efficiency test results of the β-cyclodextrin / raspberry ketone microcapsules prepared in step 1 of Examples 1-3 of the present invention;

[0029] Figure 2 These are the encapsulation efficiency test results of the β-cyclodextrin / raspberry ketone microcapsules prepared in step 1 of Examples 1 and 4-6 of this invention;

[0030] Figure 3These are the encapsulation efficiency test results of the β-cyclodextrin / raspberry ketone microcapsules prepared in step 1 of Examples 1 and 7-8 of this invention;

[0031] Figure 4 This is a bar chart showing the particle size distribution of the β-cyclodextrin / raspberry ketone microcapsules prepared in step 1 of Example 1 of this invention;

[0032] Figure 5 This is a scanning electron microscope image of the fragrance thread prepared in Example 1 of this invention;

[0033] Figure 6 This is a scanning electron microscope image of the fragrance thread prepared in Comparative Example 4 of this invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The singular forms "a," "the," and "the" used in this invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0036] It should be understood that although the terms "first", "second", "third", etc. may be used to describe various information in the present invention, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0037] This invention provides a method for preparing a core-sheath structure incense thread, which includes the following steps:

[0038] Step a) Using β-cyclodextrin as the wall material and fragrance as the core material, β-cyclodextrin / fragrance microcapsules were prepared by inclusion method;

[0039] Step b) Dissolve the β-cyclodextrin / fragrance microcapsules and polylactic acid in a solvent to obtain a core spinning solution; dissolve the polylactic acid in a solvent to obtain a sheath spinning solution;

[0040] Step c) Coaxial spinning is performed using wet spinning, with the spinning solution for the central axis being the core layer spinning solution and the spinning solution for the outer axis being the sheath layer spinning solution, to obtain a core-sheath structure fragrance thread.

[0041] Step a) above describes the preparation of β-cyclodextrin / fragrance microcapsules. This step utilizes the hydrophobic cavities of β-cyclodextrin (β-CD) to encapsulate fragrance molecules, forming core-shell microcapsules. This structure isolates the fragrance from the external environment, enhancing its thermal stability and sustained-release properties. β-cyclodextrin is chosen as the wall material in this step. Its cavity structure allows for the encapsulation of fragrance molecules through its internal hydrophobic cavities. However, using β-cyclodextrin as a wall material eliminates the need for cross-linking agents, thus complicating the preparation process.

[0042] As a preferred embodiment, the flavoring is raspberry ketone, and correspondingly, the β-cyclodextrin / flavoring microcapsules prepared in this step are β-cyclodextrin / raspberry ketone microcapsules. Raspberry ketone is a key component of tobacco flavoring, and its molecular size has a high degree of matching with the β-CD cavity, making it easy to be encapsulated.

[0043] The preferred embodiment of step a) is as follows:

[0044] Step a1) Dissolve β-cyclodextrin in water and stir in a heated water bath to prepare a wall material solution with a concentration of 1% to 6%;

[0045] Step a2) Mix raspberry ketone with surfactant, add to deionized water, and homogenize and emulsify to form raspberry ketone emulsion; the concentration of raspberry ketone in the raspberry ketone emulsion is 5% to 15%, and the mass ratio of surfactant to raspberry ketone is 1 to 5:100.

[0046] Step a3) Add the raspberry ketone emulsion to the wall material solution and stir to emulsify. The mass ratio of raspberry ketone to β-cyclodextrin in the mixed emulsion is 1:3 to 9.

[0047] Step a4) After the emulsified solution was cooled to room temperature, it was centrifuged, washed and dried to obtain β-cyclodextrin / raspberry ketone microcapsules.

[0048] Step a1) is the process of preparing the wall material solution. Heating promotes the complete dissolution of β-CD, forming a homogeneous wall material solution. The preferred water bath temperature is 50–70°C. The concentration of β-CD in the wall material solution is 1%–6%, with 6% being the most preferred.

[0049] Step a2) is the oil-phase emulsification step. The surfactant reduces the interfacial tension between raspberry ketone and water, and high-speed homogenization disperses the fragrance into submicron-sized oil droplets, forming a stable emulsion that provides a basis for subsequent inclusion. The concentration of raspberry ketone in the emulsion is 5%–15%, more preferably 15%. In this step, the surfactant is preferably Span 80, as it has weaker competitive activity and does not preferentially occupy cavities. The mass ratio of surfactant to raspberry ketone is 1–5:100. The preferred speed for homogenization and emulsification is 8000–10000 rpm, and the preferred time is 2–5 min.

[0050] Step a3) is the inclusion reaction step. Stirring and emulsification ensure sufficient contact between the raspberry ketone emulsion and the wall material solution. The stirring speed is preferably 500–800 rpm. Heating promotes the movement of β-CD molecules and facilitates the capture of raspberry ketone molecules by the hydrophobic cavities. The heating temperature is preferably 30–60°C; the heating time is preferably 1–3 h. More preferably, the heating temperature is 50–60°C and the time is 2–3 h. The mass ratio of raspberry ketone to β-cyclodextrin is 1:3–9, preferably 1:3–6. Most preferably, the mass ratio of raspberry ketone to cyclodextrin is 3:1, the heating temperature is 50°C, and the time is 2 h.

[0051] Step a4) is the separation and purification step of the formed microcapsules. The lower layer precipitate is separated by centrifugation and then washed, specifically by deionization washing, to remove free fragrance and surfactant. Finally, the microcapsules are dried to obtain β-cyclodextrin / raspberry ketone microcapsules. Freeze drying is preferred to avoid fragrance loss caused by heat drying.

[0052] Step b) is the preparation of the spinning solution. The core spinning solution comprises β-cyclodextrin / fragrance microcapsules, polylactic acid (PLA), and a solvent. The microcapsules are uniformly dispersed in the PLA solution, allowing the fragrance microcapsules to embed into the fiber core. The sheath spinning solution comprises PLA and a solvent. The pure PLA solution forms an outer encapsulation structure, which, after solidification, constitutes a dense sheath, physically preventing premature escape of the fragrance from the core and enhancing storage stability. PLA is chosen as the main component of the fragrance thread because it primarily provides mechanical support and has excellent degradability and recyclability. Dichloromethane is preferably used as the solvent. The mass ratio of β-cyclodextrin / fragrance microcapsules, PLA, and dichloromethane in the core spinning solution is 5–15:10–25:60–90, preferably 10–15:10–12:73–80. β-Cyclodextrin / fragrance microcapsules, polylactic acid, and dichloromethane are preferably uniformly dispersed and mixed by ultrasonication for a preferred time of 10–40 min. In the sheath spinning solution, the mass ratio of polylactic acid to dichloromethane is 10–15:85–90. Polylactic acid and dichloromethane are preferably uniformly dispersed and mixed by ultrasonication for a preferred time of 20–30 min.

[0053] Step c) involves coaxial spinning using wet spinning. Wet spinning allows for the direct preparation of single fibers of the desired diameter; it can be performed at room temperature, is not demanding on preparation conditions, and exhibits high compatibility; the structure is designable; and it is performed at low temperatures, avoiding the decomposition of fragrance caused by the high temperatures of melt spinning. Coaxial spinning completely encapsulates the core layer (containing microcapsules) with a sheath layer (pure PLA), forming a core-sheath sustained-release structure. Preferably, in this step, the central spindle needle size is 18–20 G, and the outer spindle needle size is 14–16 G; the central spindle spinning solution flow rate is 0.8–1.5 mL / h, and the outer spindle spinning solution flow rate is 2–4 mL / h. More preferably, the central spindle needle size is 16 G, and the outer spindle needle size is 120 G; the central spindle spinning solution flow rate is 1 mL / h, and the outer spindle spinning solution flow rate is 3 mL / h. The coagulation bath solidifies the PLA fibers through phase separation and completely removes the solvent. Preferably, the coagulation bath is an ethanol solution with a concentration of 50-100% and a temperature of 15-35°C. More preferably, the coagulation bath is an ethanol solution with a concentration of 90% and a temperature of 20°C.

[0054] Another embodiment of the present invention provides a core-sheath structure incense thread, which is prepared according to the method described in any one of the above embodiments. The specific implementation method is the same as that of the foregoing embodiments, and will not be repeated here.

[0055] Another embodiment of the present invention provides a cigarette filter rod having the aforementioned core-sheath structure aroma thread. The filter rod can be a cellulose acetate filter rod, a polypropylene filter rod, or a paper filter rod. The cigarette can be a conventional cigarette or a heated cigarette.

[0056] The core-sheath structure incense thread and its preparation method provided in this invention have the following advantages:

[0057] 1. This method first uses β-cyclodextrin as the wall material to encapsulate the fragrance into microcapsules. Then, the microcapsules are coaxially wet-spun with polylactic acid using a blending method to construct a core-sheath structure. The core layer contains microcapsules, and the sheath layer is pure polylactic acid. When flue gas passes through, the gaps in the microcapsule walls of the core layer are heated. Under the action of β-cyclodextrin locking the fragrance molecules through van der Waals forces, the fragrance is slowly released. The dense PLA layer of the sheath layer physically blocks the rapid escape of the fragrance and slows down the release rate.

[0058] 2. Wet spinning is employed, preventing the fragrance from being heated during the spinning process and suppressing the problem of fragrance volatilization and decomposition due to heat during processing. The polylactic acid sheath layer encapsulating the fragrance microcapsule core reduces fragrance loss during daily storage. Both polylactic acid and β-cyclodextrin are biodegradable materials, meeting the green standards of the tobacco industry.

[0059] 3. This invention uses microcapsule embedding combined with wet spinning integrated technology to prepare fragrance thread with stable ability to add and release fragrance. When high-temperature smoke passes through the fragrance thread, raspberry ketone can be released from the micro gaps on the microcapsule wall, thereby ensuring the persistence of cigarette aroma.

[0060] 4. Experiments have shown that β-cyclodextrin inclusion complexation improves the retention rate of raspberry ketone at 30℃ to 95%, which is 47% higher than direct addition. During the inhalation process, the release rate accounts for more than 50% in the first 3 puffs, and the release rate remains stable in the last 4 puffs, with a significant improvement in aroma uniformity.

[0061] The technical solution of the present invention will be further described below in conjunction with specific embodiments:

[0062] Example 1

[0063] 1. Raspberry ketone was mixed with Span 80 (1% of raspberry ketone by mass), and deionized water (final raspberry ketone concentration 15%) was added. The mixture was homogenized and emulsified at 10,000 rpm for 3 min to form a homogeneous emulsion. β-Cyclodextrin was dissolved in water to a concentration of 6%. The raspberry ketone flavor emulsion was slowly added dropwise, resulting in a final mixed emulsion with a raspberry ketone:β-cyclodextrin mass ratio of 1:3. The mixture was stirred at 800 rpm for 2 h in a constant temperature water bath at 50°C. After returning to room temperature, the precipitate was collected by centrifugation, washed with deionized water, filtered, and freeze-dried to obtain β-cyclodextrin / raspberry ketone microcapsules.

[0064] 2. Mix β-cyclodextrin / raspberry ketone microcapsules, polylactic acid, and dichloromethane at a mass ratio of 15:10:75 until homogeneous, then ultrasonically disperse for 20 minutes and inject into syringe 1. Mix polylactic acid and dichloromethane at a mass ratio of 15:85 until homogeneous, then inject into syringe 2.

[0065] 3. Connect syringes 1 and 2 to coaxial needles 20G / 16G, with syringe 1 connected to the central shaft 20G needle and syringe 2 connected to the outer shaft 16G needle. The core flow rate of the wet spinning machine injection pump is 1mL / h, the sheath flow rate is 3mL / h, the coagulation bath is 90% ethanol solution, and the temperature is 20℃. After coagulation, wash with water and dry to obtain a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0066] Example 2

[0067] The only difference from Example 1 is that the mass ratio of raspberry ketone to β-cyclodextrin in the mixed emulsion in step 1 is adjusted to 1:6, while the rest remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0068] Example 3

[0069] The only difference from Example 1 is that the mass ratio of raspberry ketone to β-cyclodextrin in the mixed emulsion in step 1 is adjusted to 1:9, while the rest remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0070] Example 4

[0071] The only difference from Example 1 is that the temperature of the constant temperature water bath in step 1 is adjusted to 30°C, while the rest remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0072] Example 5

[0073] The only difference from Example 1 is that the temperature of the constant temperature water bath in step 1 is adjusted to 40°C, while the rest remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0074] Example 6

[0075] The only difference from Example 1 is that the temperature of the constant temperature water bath in step 1 is adjusted to 60°C, while the rest remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0076] Example 7

[0077] The only difference from Example 1 is that the stirring time of the mixed emulsion in the constant temperature water bath in step 1 is adjusted to 1 hour, while the rest remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0078] Example 8

[0079] The only difference from Example 1 is that the stirring time of the mixed emulsion in the constant temperature water bath in step 1 is adjusted to 3 hours, while the rest remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0080] Example 9

[0081] The only difference in Example 1 is that the mass ratio of β-cyclodextrin / raspberry ketone microcapsules, polylactic acid and dichloromethane in step 2 is adjusted to 10:12:78. Everything else remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0082] Comparative Example 1

[0083] The difference from Example 1 is that step 1 is omitted; the spinning solution injected into syringe 1 in step 2 is:

[0084] The raspberry ketone, polylactic acid and dichloromethane were mixed evenly in a mass ratio of 15:10:75 and then ultrasonically dispersed for 20 minutes to obtain the final product.

[0085] Everything else remained the same as in Example 1, resulting in a polylactic acid composite core-sheath structure fragrance thread.

[0086] Comparative Example 2

[0087] The difference from Example 1 is that the preparation of the sheath spinning solution is omitted in step 2. Instead, the mixed spinning solution of β-cyclodextrin / raspberry ketone microcapsules, polylactic acid and dichloromethane (with the same ratio as step 2 in Example 1) is directly injected into the syringe for wet spinning. The process parameters are as follows: 16G syringe needle, injection pump flow rate of 3 mL / h, coagulation bath of 90% ethanol solution, temperature of 20°C, and after coagulation, the product is washed with water and dried to obtain polylactic acid composite fragrance thread containing raspberry ketone microcapsules.

[0088] Comparative Example 3

[0089] The difference from Example 1 is that the order of adding the oil and water phases in Example 1 is adjusted, and the β-cyclodextrin aqueous solution is added dropwise to the raspberry ketone oil phase. Everything else remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0090] Comparative Example 4

[0091] The difference from Example 1 is that the flow rate of the core and sheath of the injection pump in step 3 of Example 1 is adjusted to 1 mL / h, while the rest remains the same as in Example 1, resulting in a core-sheath structure fragrance thread containing raspberry ketone microcapsules.

[0092] The Influence of Plasma-to-Wall Ratio, Encapsulation Temperature, and Stirring Time on Flavor Encapsulation Efficiency

[0093] The encapsulation efficiency of the β-cyclodextrin / raspberry ketone microcapsules prepared in step 1 of Examples 1-3 was tested to investigate the effect of different plasmolysis ratios (mass ratio of β-cyclodextrin to raspberry ketone) on the encapsulation efficiency. The test results are as follows: Figure 1 As shown.

[0094] The encapsulation efficiency of the β-cyclodextrin / raspberry ketone microcapsules prepared in Step 1 of Examples 1 and 4-6 was tested, and the effect of different encapsulation temperatures (temperature of the constant-temperature water bath) on the encapsulation efficiency was studied. The test results are as follows: Figure 2 As shown.

[0095] The encapsulation efficiency of the β-cyclodextrin / raspberry ketone microcapsules prepared in Step 1 of Examples 1 and 7-8 was tested, and the effect of different stirring times on the encapsulation efficiency was studied. The test results are as follows: Figure 3 As shown.

[0096] Depend on Figure 1-3 It can be seen that the optimal preparation conditions for microcapsules are as follows:

[0097] The mass ratio of raspberry ketone to cyclodextrin is 3:1, the reaction temperature is 50℃, and the emulsification time is 2h; or, the mass ratio of raspberry ketone to cyclodextrin is 6:1, the reaction temperature is 60℃, and the emulsification time is 3h.

[0098] The above conditions result in a high microcapsule encapsulation rate, leading to a higher fragrance content in the prepared fragrance thread under the same conditions. Considering energy optimization, the parameters in Example 1 were selected as the optimal parameters.

[0099] [Particle size distribution of microcapsules]

[0100] A laser particle size analyzer (Brookhaven, ZetaPlus) was used. The particle size of the β-cyclodextrin / raspberry ketone microcapsules prepared in step 1 of Example 1 was tested, and the particle size distribution is shown in the figure. Figure 4 As shown.

[0101] Depend on Figure 4 It can be seen that the particle size of the raspberry microcapsules prepared in Example 1 is mostly distributed between 200-500 nm, which will not affect the subsequent wet spinning process.

[0102] The effect of spinning solution flow rate on fiber morphology

[0103] Scanning electron microscope (SEM) images of the fragrance threads prepared in Example 1 and Comparative Example 4 are shown below. Figure 5 and Figure 6 As shown. By Figure 5 and Figure 6 It can be seen that the flow rate of the spinning solution in the core and sheath layers affects the diameter distribution of the fibers. The fragrance yarn spun in Example 1 has a uniform diameter distribution. Figure 5 However, if the flow rates of both the core and sheath are adjusted to 1 mL / h, uneven distribution of the sheath on the fiber surface and obvious internal pores will occur. Figure 6 ).

[0104] [Incense Thread Thermal Stability Test]

[0105] The fragrance thread samples prepared in Examples 1, 9, 1, and 2 were designated as A, B, C, and D, respectively. The thermal stability of the four fragrance thread samples was tested: the fragrance thread samples were placed in a thermogravimetric analyzer [fully automatic thermogravimetric analyzer (Mettler TGA2)], and the holding temperature was set to 30, 50, 80, and 100°C for 6 hours. The volatile matter of the fragrance was then tested, as detailed in Table 1.

[0106] Table 1. Fragrance evaporation (mg) of four types of incense sticks at different temperatures.

[0107]

[0108]

[0109] As can be seen from Table 1, the coating of β-cyclodextrin and the core-sheath structure can significantly improve the thermodynamic stability of raspberry ketone and effectively improve its stability at room temperature. However, it also reduces the release of fragrance during the extraction process to some extent. The loss caused by the β-cyclodextrin wall material and core-sheath structure can be compensated by increasing the content of raspberry ketone microcapsules.

[0110] [Aroma Release Uniformity Test]

[0111] The flavored cigarette samples prepared in Examples 1, 9, Comparative Example 1, and Comparative Example 2 were added to cigarette filters (the amount added was 1.2% of the filter weight), and cigarette samples A, B, C, and D containing flavored cigarettes were rolled. After being stored at room temperature for one month, the smoke from the cigarettes with added flavored cigarettes was inhaled one puff at a time using a linear smoking machine. The specific inhalation parameters were: inhalation volume 50 mL, inhalation duration 2 s, and inhalation interval 30 s. The content of raspberry ketone in the mainstream smoke was tested, and the test results are shown in Table 2.

[0112] Table 2 Flavor content (%) in each puff of smoke for four types of cigarette products

[0113]

[0114] As can be seen from Table 2, the fragrance threads A and B prepared in the embodiments of the present invention have good thermal stability, and the fragrance is released more evenly and for a longer period of time during inhalation.

[0115] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a core-sheath structure incense thread, characterized in that, include: Step a) Using β-cyclodextrin as the wall material and fragrance as the core material, β-cyclodextrin / fragrance microcapsules were prepared by inclusion method; Step b) Dissolve the β-cyclodextrin / fragrance microcapsules and polylactic acid in a solvent to obtain a core spinning solution; dissolve the polylactic acid in a solvent to obtain a sheath spinning solution; Step c) Coaxial spinning is performed using wet spinning, with the spinning solution for the central axis being the core layer spinning solution and the spinning solution for the outer axis being the sheath layer spinning solution, to obtain a core-sheath structure fragrance thread.

2. The preparation method according to claim 1, characterized in that, In step a), the flavoring is raspberry ketone, and the β-cyclodextrin / flavoring microcapsules are β-cyclodextrin / raspberry ketone microcapsules.

3. The preparation method according to claim 2, characterized in that, Step a) specifically refers to: Step a1) Dissolve β-cyclodextrin in water and stir in a heated water bath to prepare a wall material solution with a concentration of 1% to 6%; Step a2) Mix raspberry ketone with surfactant, add to deionized water, and homogenize and emulsify to form raspberry ketone emulsion; the concentration of raspberry ketone in the raspberry ketone emulsion is 5% to 15%, and the mass ratio of surfactant to raspberry ketone is 1 to 5:

100. Step a3) Add the raspberry ketone emulsion to the wall material solution and stir to emulsify. The mass ratio of raspberry ketone to β-cyclodextrin in the mixed emulsion is 1:3 to 9. Step a4) After the emulsified solution was cooled to room temperature, it was centrifuged, washed and dried to obtain β-cyclodextrin / raspberry ketone microcapsules.

4. The preparation method according to claim 3, characterized in that, In step a1), the water bath temperature is 50–70°C; and / or, in step a2), the surfactant is Span 80, the homogenization speed is 8000–10000 rpm, and the time is 2–5 min.

5. The preparation method according to claim 3, characterized in that, In step a3), the stirring speed for emulsification is 500-800 rpm and the temperature is 30-60℃; and / or, in step a4), the drying is freeze drying.

6. The preparation method according to claim 3, characterized in that, In step b), the solvent is dichloromethane, and the mass ratio of β-cyclodextrin / fragrance microcapsules, polylactic acid and dichloromethane in the core spinning solution is 5-15:10-25:60-90; the mass ratio of polylactic acid and dichloromethane in the sheath spinning solution is 10-15:85-90.

7. The preparation method according to claim 1, characterized in that, In step c), the size of the central shaft needle is 18-20G, and the size of the outer shaft needle is 14-16G; the flow rate of the central shaft spinning solution is 0.8-1.5mL / h, and the flow rate of the outer shaft spinning solution is 2-4mL / h.

8. The preparation method according to claim 1, characterized in that, In step c), the coagulation bath is an ethanol solution with a concentration of 50-100% and a temperature of 15-35°C.

9. A core-sheath structure incense thread, characterized in that, It is prepared according to the method described in any one of claims 1-8.

10. A cigarette filter rod, characterized in that, It is provided with the core-sheath structure incense thread as described in claim 9.

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