Slow-release nanofiber, preparation method thereof, and cigarette

Abstract

The present invention relates to the field of cigarette flavoring technology, and in particular to slow-release nanofibers, their preparation method, and cigarettes. The slow-release nanofiber preparation method comprises: step a) dissolving a high molecular weight polymer in a solvent under heating and stirring conditions to obtain a polymer solution; step b) dispersing a flavor and graphene oxide in the polymer solution to obtain a flavor / graphene oxide / polymer emulsion; and step c) electrospinning the flavor / graphene oxide / polymer emulsion to obtain slow-release nanofibers. The slow-release nanofibers prepared by this method can stably store the flavor at low temperatures and slowly and evenly release it at high temperatures, thereby achieving controlled flavor release.

Description

Technical Field

[0001] The present invention relates to the technical field of cigarette flavoring, in particular to slow-release nanofibers and a preparation method thereof, and cigarettes. Background Art

[0002] Studies have found that flavored tobacco products are more popular with consumers. Common flavoring methods currently used in the market include tobacco flavoring, filter flavoring, cigarette paper flavoring, and packaging material flavoring. Compared to other flavoring methods, filter flavoring can reduce the retention of flavorings by tobacco, reduce the odor caused by the burning of flavorings in tobacco, and also provide a fresh smoking experience for the user. Flavorings, as a highly volatile substance, can be quickly perceived by the human body. However, cigarette flavoring components generally have a small molecular weight, a low boiling point, and are easily volatile. Therefore, they are prone to volatility during storage, and it is easy for the flavor to be strong in the early stages of the cigarette burning process and disappear in the later stages. These problems, namely, rapid and uneven flavor release, result in poor stability and persistence of the cigarette aroma, reducing the consumer experience.

[0003] Controlled-release technology is a substance-controlled release technology that enables the slow or controlled release of a target substance from a release medium by treating the target substance or relying on the special properties of auxiliary materials. By subjecting flavors and fragrances to controlled-release treatment, the duration of fragrance release can be extended. Currently, the controlled-release of flavors primarily utilizes microencapsulation technology. Microencapsulation of flavors involves using a film-forming material (wall material) to protect the liquid flavor (core material) by forming tiny particles. Common methods for preparing flavor microcapsules include simple coacervation, complex coacervation, spray drying, in-situ polymerization, and interfacial polymerization. Microencapsulation of flavors allows the release rate to be controlled under certain conditions. Flavor microcapsules typically utilize natural or synthetic polymers as their wall materials, such as natural gum arabic, gelatin, chitosan, β-cyclodextrin, and cellulose. The microcapsules are in the form of tiny particles. Existing flavor microcapsules have a certain positive effect on the sustained release of flavors, but they still have the following problems: first, the retention rate of the flavor in the microcapsule at room temperature decreases rapidly over time, that is, the locking effect of the flavor at room temperature needs to be improved; second, the aroma release is not uniform under high temperature conditions and the taste is unstable. Summary of the Invention

[0004] In order to solve or partially solve the problems existing in the related art, the present invention provides a slow-release nanofiber, a preparation method thereof, and a cigarette.

[0005] The present invention provides a method for preparing slow-release nanofibers, which comprises:

[0006] Step a), dissolving the high molecular weight polymer in a solvent under heating and stirring conditions to obtain a polymer solution;

[0007] Step b), dispersing the essence and graphene oxide in the polymer solution to obtain an essence / graphene oxide / polymer emulsion;

[0008] Step c), electrospinning the essence / graphene oxide / polymer emulsion to obtain slow-release nanofibers.

[0009] Furthermore, the high molecular weight polymer is a degradable polymer.

[0010] Furthermore, the heating temperature in step a) is 30° C. to 110° C., and the stirring speed is 1000 r / min to 10000 r / min.

[0011] Furthermore, the concentration of the polymer emulsion is 6 wt% to 20 wt%.

[0012] Furthermore, the step b) adopts ultrasonic dispersion method.

[0013] Furthermore, the essence is one or a mixture of peppermint essential oil, citral essential oil, lavender essential oil, and rose essential oil.

[0014] Furthermore, the weight ratio of the essence, graphene oxide and high molecular polymer in the essence / graphene oxide / polymer emulsion is (2-200):(1-5):100.

[0015] Furthermore, in the step c), the spinning voltage is set to 15 kV to 30 kV, the liquid feeding rate is set to 0.1 mL / h to 5 mL / h, and the receiving distance is set to 10 cm to 35 cm.

[0016] The present invention also provides a slow-release nanofiber, which is prepared according to any one of the above methods.

[0017] The present invention also provides a cigarette, the filter segment of which contains the above-mentioned slow-release nanofiber.

[0018] The method for preparing the sustained-release nanofibers provided by the present invention can have the following beneficial effects:

[0019] The slow-release nanofibers prepared by the present invention use a high molecular weight polymer as a loading material and graphene oxide as a flavor adsorbent and thermal conductor. The slow-release nanofibers are obtained by electrospinning a flavor / graphene oxide / polymer emulsion. In the prepared slow-release nanofibers, the polymer's encapsulation and the graphene oxide's adsorption of the flavor restrict the diffusion of flavor molecules, thereby enhancing the fiber's ability to lock the flavor at room temperature and reducing the release of the flavor at room temperature. Furthermore, graphene oxide has excellent thermal conductivity and is evenly dispersed within the fibers. This allows heat to be quickly transferred to all parts of the fiber during heating / burning of the cigarette, resulting in more uniform aroma release from all locations. Ultimately, the flavor is stably stored at low temperatures and slowly and evenly released at high temperatures, achieving controlled flavor release.

[0020] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0022] Figure 1 is a scanning electron microscope image of the sustained-release nanofiber prepared in Comparative Example 1 of the present invention;

[0023] Figure 2 is a scanning electron microscope image of the sustained-release nanofiber prepared in Example 1 of the present invention;

[0024] Figure 3 is a scanning electron microscope image of the sustained-release nanofiber prepared in Example 2 of the present invention;

[0025] Figure 4 is a scanning electron microscope image of the sustained-release nanofiber prepared in Example 3 of the present invention;

[0026] Figure 5 is a graph showing the change in flavor retention rate over time at room temperature for different samples prepared in an embodiment of the present invention;

[0027] Figure 6 is a graph showing the change in aroma values ​​of different samples prepared in an embodiment of the present invention over time;

[0028] Figure 7 3 is a graph showing the change in flavor retention rate of different samples prepared in accordance with an embodiment of the present invention over time. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] 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.

[0031] 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.

[0032] The present invention provides a method for preparing slow-release nanofibers, which comprises the following steps:

[0033] Step a), dissolving the high molecular weight polymer in a solvent under heating and stirring conditions to obtain a polymer solution;

[0034] Step b), dispersing the essence and graphene oxide in the polymer solution, stirring at high speed to obtain an essence / graphene oxide / polymer emulsion;

[0035] Step c), electrospinning the essence / graphene oxide / polymer emulsion to obtain slow-release nanofibers.

[0036] First, the inventors of this application considered using electrospinning to prepare nanofibers, encapsulating the flavor in a high molecular polymer to achieve a sustained release of the flavor. The present invention uses an emulsion electrostatic method to prepare nanofibers, which appear as dense films in macroscopic terms and as polymer nanofiber layers in microscopic terms. Compared with traditional flavor microcapsules, they have a larger specific surface area and can carry more flavors. The prepared nanofibers are membranous materials with a relatively firm wall structure that is not easily detached or damaged, and thus have a more reliable effect on blocking the flavor. Secondly, graphene oxide is also added to the nanofiber raw material to increase the flavor loading and distribution uniformity in the fiber, and to make the aroma release more balanced. Specifically:

[0037] In the slow-release nanofibers prepared by the present invention, high molecular polymer is the main load material, which forms the wall material of the nanofiber and encapsulates the essence inside the fiber. The addition of graphene oxide has the following effects: on the one hand, during the mixing process, the oxidized groups on the graphene oxide combine with the hydroxyl and carboxyl groups on the flavor molecules, embedding the flavor molecules into the carbon ring structure of the graphene oxide. This makes the flavor more evenly dispersed in the polymer solution system, increasing the polymer's flavor loading capacity while preventing collision and binding between small flavor droplets. This helps control the size of the flavor droplets, preventing excessive flavor droplet volume from affecting the continuity of subsequent spinning. This improves the flavor loading capacity and distribution uniformity in the prepared nanofiber material and helps improve the fiber formation process. After the product is formed, the good adsorption of graphene oxide for flavor can further limit the diffusion of flavor molecules at room temperature, that is, it can improve the fiber product's ability to lock the flavor at room temperature and reduce the release of the flavor at room temperature. On the other hand, graphene oxide has good thermal conductivity. Graphene oxide is evenly dispersed in the fiber, allowing heat to be quickly introduced to all parts of the fiber during heating / burning, resulting in more uniform aroma release from all parts of the fiber.

[0038] In the above preparation method, step a) is the process of first dissolving the polymer to obtain a polymer solution. In order to improve the speed and uniformity of polymer dissolution, this step is carried out under heating and stirring conditions. The above polymer is preferably a degradable polymer, preferably a mixture of one or more of polyvinyl alcohol, polyethylene oxide, polylactic acid, and cellulose acetate; the solvent is preferably a mixture of one or more of formic acid, water, ethanol, dichloromethane, N,N-dimethylformamide, and acetone; the heating temperature is preferably 30°C to 110°C, and the stirring speed is preferably 1000r / min to 10000r / min. More preferably, the polymer is polyvinyl alcohol and the solvent is deionized water, or the polymer is cellulose acetate and the solvent is N,N-dimethylformamide and acetone (volume ratio of 7:3). For the former, it is further preferred that the heating temperature is 60°C to 90°C. For the latter, it is further preferred that the heating temperature is 50°C to 70°C. The polymer concentration in the polymer solution obtained in this step is preferably 6 wt % to 20 wt %, more preferably 10 wt % to 15 wt %, and most preferably 11 wt % to 12 wt %.

[0039] Step b) is the step of mixing the raw materials to prepare a spinning emulsion. During the dispersion and mixing process, the fragrance molecules combine with the graphene oxide, and both are dispersed in the polymer and encapsulated by the polymer. To improve the uniformity of the dispersion of the fragrance molecules and graphene oxide, this step preferably utilizes ultrasonic dispersion, with the ultrasonic frequency preferably being 20 kHz. The fragrance can be one or a mixture of peppermint essential oil, citral essential oil, lavender essential oil, or rose essential oil. The graphene oxide can be a single layer or a multilayer. The weight ratio of fragrance, graphene oxide, and polymer in the resulting fragrance / graphene oxide / polymer emulsion is preferably (2-200):(1-5):100, more preferably (5-50):(1-5):100. This mixing ratio provides a spinning emulsion with suitable spinning performance, high fragrance loading, and uniform loading. More preferably, the weight ratio of flavor, graphene oxide and polymer is (8-20):(2-3):100, and further preferably, the weight ratio of flavor, graphene oxide and polymer is 10:2:100.

[0040] Step c) involves electrostatically spinning the spinning emulsion prepared in step b), namely the fragrance / graphene oxide / polymer emulsion, to produce slow-release nanofibers. Electrospinning can produce membranes composed of nanometer- to micrometer-sized fibers with a high surface-to-volume ratio and high membrane porosity, facilitating full and uniform contact between high-temperature flue gas and the slow-release fibers, thereby improving the uniformity and stability of fragrance release. The process conditions for this step are preferably set as follows: a spinning voltage of 15kV to 30kV, a liquid feed rate of 0.1mL / h to 5mL / h, and a receiving distance of 10cm to 35cm. These process conditions, combined with the aforementioned spinning emulsion ratio, ensure high and uniform fragrance loading while also exhibiting good spinning properties. The resulting nanofibers are of suitable size and have a large specific surface area. Most preferably, the spinning voltage is 20kV, the liquid feed rate is 1mL / h, and the receiving distance is 15cm. The diameter of the prepared slow-release nanofibers is preferably 50 nm to 3000 nm, more preferably 100 nm to 1000 nm. After electrospinning, a washing and drying step is preferably performed to remove dust adsorbed on the fiber surface during the electrospinning process.

[0041] As can be seen from the above, the slow-release nanofibers prepared by the present invention use a high molecular weight polymer as a loading material and graphene oxide as an adsorbent and thermal conductor for the flavor, and are obtained by electrospinning a flavor / graphene oxide / polymer emulsion. In the prepared slow-release nanofibers, the polymer's encapsulation and the graphene oxide's adsorption of the flavor restrict the diffusion of the flavor molecules, thereby improving the fiber's ability to lock the flavor at room temperature and reducing the release of the flavor at room temperature. In addition, graphene oxide has good thermal conductivity and is evenly dispersed in the fiber. This allows heat to be quickly introduced into all parts of the fiber during heating / burning of the cigarette, resulting in more uniform aroma release from all parts of the fiber. Ultimately, the flavor is stably stored at low temperatures and slowly and evenly released at high temperatures, thereby achieving the effect of controlled flavor release.

[0042] Another embodiment of the present invention also provides a slow-release nanofiber, which is prepared according to the method provided in the above embodiment. The slow-release nanofiber uses a high molecular polymer as a loading material, and wraps flavor and graphene oxide inside. Due to the wrapping property of the polymer and the adsorption property of graphene oxide on the flavor, the diffusion of flavor molecules is restricted, that is, the locking effect of the fiber product on the flavor at room temperature can be improved, and the release of the flavor at room temperature can be reduced; in addition, graphene oxide has good thermal conductivity. Graphene oxide is evenly dispersed in the fiber, so that when the cigarette is heated / burned, heat can be quickly introduced into various parts of the fiber, making the aroma release of various parts of the fiber more uniform, and ultimately making the flavor stably stored under low temperature conditions and slowly and evenly released under high temperature conditions, thereby achieving the effect of controlled release of the flavor.

[0043] Another embodiment of the present invention provides a cigarette having a filter segment containing the above-mentioned slow-release nanofibers. Due to the above-mentioned advantages of the slow-release nanofibers, the cigarette has the advantages of small aroma loss at room temperature and uniform aroma release and balanced taste at high temperature.

[0044] The technical solution of the present invention will be further described below in conjunction with specific embodiments:

[0045] Comparative Example 1

[0046] Prepare a PVA solution with a mass fraction of 11%, using deionized water as the solvent, stir at 80°C for 3 hours at a stirring speed of 200 rpm to fully dissolve the PVA, then add peppermint essential oil with a mass fraction of 10% relative to PVA to the above PVA solution, ultrasonically treat for 20 minutes at an ultrasonic frequency of 20 kHz to mix the solution evenly, and prepare a spinning solution. Pour the spinning solution into the liquid supply device of the electrospinning machine for spinning, set the feed rate to 0.9 mL / min, the spinning distance to 18 cm, and the voltage to 23 kV, and prepare slow-release nanofibers using the above method, numbered: Sample 1. The diameter of the obtained slow-release nanofibers is 650 nm, and the scanning electron microscope image is as shown below. Figure 1 shown.

[0047] Example 1

[0048] Prepare a PVA solution with a mass fraction of 11%, using deionized water as the solvent, stir at 80°C for 3 hours at a stirring speed of 200rpm to fully dissolve the PVA. Then add peppermint essential oil with a mass fraction of 10% relative to PVA and GO with a mass fraction of 2% relative to PVA (purchased from Shenzhen Guoheng Technology Co., Ltd., model GH-G00202G, the same as in the following examples) to the above PVA solution, and ultrasonically treat for 20 minutes at an ultrasonic frequency of 20kHz to mix the solution evenly to prepare a spinning solution. Pour the spinning solution into the liquid supply device of the electrospinning machine for spinning, set the feed rate to 1.0mL / min, the spinning distance to 15cm, and the voltage to 20kV, and use the above method to prepare slow-release nanofibers, numbered: Sample 2. The diameter of the obtained slow-release nanofibers is 600nm, and the scanning electron microscope image is as shown below. Figure 2 shown.

[0049] Example 2

[0050] Prepare a PVA solution with a mass fraction of 11%, using deionized water as the solvent, stir at 80°C for 3 hours at a stirring speed of 200 rpm to fully dissolve the PVA, then add rose essential oil with a mass fraction of 10% relative to PVA and GO with a mass fraction of 2% relative to PVA to the above PVA solution, perform ultrasonic treatment for 20 minutes at an ultrasonic frequency of 20 kHz to mix the solution evenly, and prepare a spinning solution. Pour the spinning solution into the liquid supply device of the electrospinning machine for spinning, set the feed rate to 1.0 mL / min, the spinning distance to 15 cm, and the voltage to 20 kV, and prepare slow-release nanofibers using the above method, numbered: Sample 3. The diameter of the obtained slow-release nanofibers is 680 nm, and the scanning electron microscope image is as shown below. Figure 3 shown.

[0051] Example 3

[0052] Prepare a 12% mass fraction of cellulose acetate (CA) solution, the solvent is N,N-dimethylformamide and acetone (volume ratio of 7:3), stir at 60℃ for 4h, stirring speed is 200rpm, so that CA is fully dissolved. Then add peppermint essential oil with a mass fraction of 10% relative to CA and GO with a mass fraction of 2% relative to CA to the above CA solution, ultrasonically treat for 20min, the ultrasonic frequency is 20kHz, so that the solution is evenly mixed to prepare a spinning solution. Pour the spinning solution into the liquid supply device of the electrospinning machine for spinning, set the feed rate to 1.0mL / min, the spinning distance to 16cm, the voltage to 22kV, and prepare slow-release nanofibers using the above method, numbered: Sample 4. The diameter of the obtained slow-release nanofibers is 700nm, and the scanning electron microscope image is as shown below. Figure 4 shown.

[0053] From the above Figures 1 to 4The results show that the emulsion system formed by peppermint essential oil, rose essential oil, PVA, and CA is relatively stable, and nanofibers with uniform thickness are formed through spinning. Graphene oxide can be evenly dispersed in the spinning solution, and no graphene oxide agglomeration is observed in the nanofibers.

[0054] The initial flavor loading of samples 1 to 4 was tested. The heating rate was set at 3°C / min, and the corresponding loading when the temperature was raised to 50°C was tested. The test results are listed in Table 1:

[0055] Table 1. Loading amount of flavor in slow-release nanofibers

[0056] Sample 1 Sample 2 Sample 3 Sample 4 Room temperature load 42％ 55％ 54％ 57％ 50℃ load capacity 20％ 14％ 14％ 15％

[0057] It can be seen from Table 1 that by adding graphene oxide, not only the loading amount of flavor can be increased, but also the release rate of flavor in a high temperature environment can be increased.

[0058] After samples 1 to 4 were placed at room temperature for 30 days, the flavor retention rates in the test samples were 74%, 95%, 95%, and 96% respectively. The flavor retention rate curves of different samples at room temperature over time are shown in Figure 2. Figure 5 As shown. Figure 5 It can be seen that the slow-release nanofibers prepared by the method of the present invention have a better effect of locking the flavor at room temperature.

[0059] The aroma value of different samples changes with time under the test condition of 50℃. Figure 6 As shown in the figure, the variation curves of flavor retention rate of different samples over time are as follows Figure 7 shown. Under 50℃ conditions:

[0060] Sample 1: The initial aroma value was 200, and after 1 minute the aroma value reached 470. After 10 minutes, the aroma value dropped to 220, and the aroma retention rate was 20%.

[0061] Sample 2: At 50°C, the initial aroma value was 130, which reached 535 after 1 minute. After 10 minutes, the aroma value still reached 535, and the aroma retention rate was 15%.

[0062] Sample 3: At 50°C, the initial aroma value was 125, which reached 535 after 1 minute. After 10 minutes, the aroma value was 530, and the aroma retention rate was 16%.

[0063] Sample 4: At 50°C, the initial aroma value was 135, which reached 530 after 1 minute, and 537 after 10 minutes. The aroma retention rate was 16%.

[0064] It can be seen from this that the sustained-release nanofibers prepared by the method of the present invention release aroma more evenly, which is beneficial to improving the stability of the smoking taste of cigarettes.

[0065] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not 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 selected to best explain the principles of the embodiments, their practical applications, or improvements to existing technologies, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing sustained-release nanofibers, characterized in that: include: Step a), dissolving a high molecular weight polymer in a solvent under heating and stirring conditions to obtain a polymer solution; the high molecular weight polymer is polyvinyl alcohol or cellulose acetate; Step b), ultrasonically dispersing the essence and graphene oxide in the polymer solution to obtain an essence / graphene oxide / polymer emulsion; the ultrasonic dispersion frequency is 20 kHz, and the time is 20 min; the weight ratio of the essence, graphene oxide and polymer is 10:2:100; the essence is one or a mixture of several of peppermint essential oil, citral essential oil, lavender essential oil and rose essential oil; Step c), electrospinning the essence / graphene oxide / polymer emulsion, setting the spinning voltage to 20 kV, the liquid feeding rate to 0.1 mL / h~5 mL / h, and the receiving distance to 10 cm~35 cm to obtain slow-release nanofibers.

2. The preparation method according to claim 1, characterized in that The heating temperature in step a) is 30° C. to 110° C., and the stirring speed is 1000 r / min to 10000 r / min.

3. The preparation method according to claim 1, characterized in that The concentration of the polymer emulsion is 6 wt % to 20 wt %.

4. A sustained-release nanofiber, characterized in that It is prepared according to the method according to any one of claims 1 to 3.

5. A cigarette, characterized in that: The filter segment contains the slow-release nanofiber according to claim 4.

Images