Composite nanofiber membrane, preparation method thereof and cigarette

Abstract

The present application relates to cigarette flavoring technology field, especially to composite nanofiber membrane and its preparation method and cigarette. The preparation method of the composite nanofiber membrane comprises the following steps: a), a high molecular polymer is added to a solvent, heated and dissolved to obtain a polymer solution; b), essence, graphene oxide and mesoporous silica are added to the polymer solution and uniformly dispersed to obtain a spinning emulsion; c), the spinning emulsion is electrospun to obtain a composite nanofiber membrane. The composite nanofiber membrane prepared by the method can stably store essence under low temperature conditions and slowly and uniformly release essence under high temperature environment, so that the effect of controlled release of essence is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cigarette flavoring, in particular to a composite nanofiber membrane, a preparation method thereof and a cigarette. BACKGROUND

[0002] Research has found that flavored tobacco products are more popular with consumers. The current market commonly used flavoring methods include tobacco flavoring, filter flavoring, cigarette paper flavoring and packaging material flavoring. Compared with other flavoring methods, filter flavoring can reduce the interception of tobacco on flavorings, reduce the peculiar smell caused by the burning of flavorings in tobacco, and also bring fresh smoking experience to the experimenter. As a kind of volatile substance, flavoring can be quickly perceived by the human body, but the molecular weight of cigarette flavoring ingredients is generally small, the boiling point is low, and it is easy to volatilize. Therefore, it is easy to volatilize during storage, and the situation of rich flavor in the early stage and disappearance of aroma in the later stage during cigarette burning is easy to occur. That is, the flavor is released quickly and unevenly, the stability of cigarette aroma is poor, and the persistence is poor, which reduces the experience of consumers.

[0003] The controlled release technology is a substance controlled release technology, which makes the target substance slowly or controllably release in the release medium through a certain treatment of the target substance or depending on the special property of the auxiliary material. By controlling the release of flavoring, the release time of flavoring can be prolonged. At present, the controlled release of flavoring mainly adopts microcapsule technology, which is a protection technology that uses a film-forming material (wall material) to form a small particle of liquid flavoring (core material). The commonly used preparation methods of flavoring microcapsules mainly include single condensation method, complex condensation method, spray drying method, in-situ polymerization method, interfacial polymerization method and the like. After the flavoring is microencapsulated, the release rate of the flavoring can be artificially controlled under certain conditions. The wall material of the flavoring microcapsule usually uses some natural or synthetic high molecular materials as the capsule wall, such as natural gum arabic, gelatin, chitosan, beta-cyclodextrin and cellulose, and the microcapsule form is a small particle. The existing flavoring microcapsules have a certain positive effect on the slow release of flavoring, but they still have the following problems: firstly, the retention rate of flavoring in the microcapsule decreases rapidly with time at room temperature, that is, the locking effect of flavoring at room temperature needs to be improved; secondly, the aroma release is not uniform and the taste is unstable in a high temperature environment. SUMMARY

[0004] To solve or partially solve the problems in the related art, the present application provides a composite nanofiber membrane, a preparation method thereof and a cigarette.

[0005] The present application provides a preparation method of a composite nanofiber membrane, which comprises:

[0006] Step a), adding a high molecular polymer into a solvent, heating and dissolving to obtain a polymer solution;

[0007] Step b), adding the essence, graphene oxide and mesoporous silica into the polymer solution, uniformly dispersing to obtain a spinning emulsion;

[0008] Step c), electrospinning the spinning emulsion to obtain a composite nanofiber membrane.

[0009] Further, the high molecular polymer is one or a mixture of several of polyvinyl alcohol, polyethylene oxide, polylactic acid and cellulose acetate.

[0010] Further, the concentration of the polymer emulsion is 5wt%-25wt%.

[0011] Further, step b) is specifically: adding the essence, graphene oxide and mesoporous silica into the polymer solution, ultrasonic dispersing to obtain a spinning emulsion.

[0012] Further, the essence is one or a mixture of several of mint essential oil, citral essential oil, lavender essential oil, rose essential oil, sweet orange essential oil and myrcia essential oil.

[0013] Further, the weight ratio of the essence, graphene oxide and high molecular polymer in the essence / graphene oxide / polymer emulsion is (12-24):(1-10):(1-10):100.

[0014] Further, in step c), the spinning voltage is 15kV-30kV, the feeding rate is 0.1mL / h-5mL / h, and the receiving distance is 10cm-35cm.

[0015] Further, the diameter of the composite nanofiber membrane is 100nm-1000nm.

[0016] The application also provides a composite nanofiber membrane prepared by any one of the above methods.

[0017] The application also provides a cigarette, wherein the filter stick contains the above composite nanofiber membrane.

[0018] The preparation method of the composite nanofiber membrane provided by the application can have the following beneficial effects:

[0019] The prepared composite nanofiber membrane takes a polymer as a loading material, takes graphene oxide and mesoporous silica as an adsorbent of essence, and the graphene oxide also serves as a heat conductor. The composite nanofiber membrane is obtained by electrospinning of the essence / graphene oxide / mesoporous silica / polymer emulsion. In the prepared composite nanofiber membrane, due to the wrapping property of the polymer and the adsorption property of the graphene oxide and the mesoporous silica to the essence, the diffusion of the essence molecules is limited, that is, the locking effect of the fiber product on the essence at room temperature can be improved, and the release of the essence at room temperature is reduced. In addition, the graphene oxide has good heat conduction performance, and the graphene oxide is uniformly dispersed in the fiber, so that when the cigarette is heated / combusted, heat can be quickly introduced to each part of the fiber, so that the aroma release of each part of the fiber is more uniform, and finally the essence is stably stored at low temperature and slowly and uniformly released at high temperature, so that the effect of controllable release of the essence is achieved.

[0020] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0021] The exemplary embodiments of the present application will be described in more detail by combining the accompanying drawings.

[0022] Figure 1 is a scanning electron microscope image of the composite nanofiber membrane prepared in Comparative Example 1 of the present application;

[0023] Figure 2 is a scanning electron microscope image of the composite nanofiber membrane prepared in Example 1 of the present application;

[0024] Figure 3 is a scanning electron microscope image of the composite nanofiber membrane prepared in Example 2 of the present application;

[0025] Figure 4 is a scanning electron microscope image of the composite nanofiber membrane prepared in Example 3 of the present application;

[0026] Figure 5 is a curve graph of the retention rate of essence of different samples prepared in the present application with time at room temperature;

[0027] Figure 6 is a curve graph of the aroma value of different samples prepared in the present application with time;

[0028] Figure 7 is a curve graph of the retention rate of essence of different samples prepared in the present application with time. DETAILED DESCRIPTION

[0029] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0030] The terminology used in the present application is merely for the purpose of describing particular embodiments and is not intended to limit the present application. As used in the present application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0031] It should be understood that, although the terms "first", "second", "third", etc. can be employed in the present application to describe various information, the information should not be limited to these terms. These terms are only used to distinguish one piece of information from another piece of information of the same type. For example, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information, without departing from the scope of the present application. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0032] The present application provides a preparation method of a composite nanofiber membrane, comprising the following steps:

[0033] Step a), adding a high molecular polymer into a solvent, heating and dissolving to obtain a polymer solution;

[0034] Step b), adding essence, graphene oxide and mesoporous silica into the polymer solution, uniformly dispersing to obtain a spinning emulsion;

[0035] Step c), electrospinning the spinning emulsion to obtain a composite nanofiber membrane.

[0036] Firstly, the present application inventors consider using electrospinning method to prepare nanofiber membrane, and encapsulate the essence in the polymer to realize the slow release of essence. The present application uses emulsion electrostatic method to prepare nanofiber membrane, which is macroscopically dense film and microscopically polymer nanofiber layer. Compared with traditional essence microcapsules, the specific surface area is larger, and the loading capacity of essence is also more. The prepared nanofiber is a membrane material, and the structure of the wall material is more reliable, and is not easy to fall off or break, and the blocking effect of essence is more reliable. Secondly, graphene oxide and mesoporous silica are added to the nanofiber raw material, which can improve the loading capacity and uniformity of essence in the fiber, and make the fragrance release more balanced. Specifically:

[0037] In the composite nanofiber membrane prepared by the present application, the polymer is the main loading material, which forms the wall material of nanofiber and encapsulates the essence in the fiber. The addition of graphene oxide and mesoporous silica has the following effects: on the one hand, the high specific surface area of mesoporous silica and the characteristics of the oxidation groups of graphene oxide which are easy to combine with the hydroxyl and carboxyl groups on the essence molecules are used to synergistically adsorb the essence molecules, which helps the essence to disperse more uniformly in the polymer solution system, increases the loading capacity of the polymer to the essence, avoids the collision and combination between the small droplets of essence, controls the size of the essence droplets, avoids the influence of the large volume of essence droplets on the continuity of subsequent spinning, thereby improves the loading capacity and uniformity of the essence in the prepared nanofiber material, and is beneficial to improve the spinnability of the spinning process; after the product is formed, the good adsorption of graphene oxide and mesoporous silica to the essence can further limit the diffusion of essence molecules at room temperature, that is, it can improve the locking effect of the fiber product to the essence at room temperature, and reduce the release of essence at room temperature; on the other hand, graphene oxide has good thermal conductivity, and the uniform dispersion of graphene oxide in the fiber makes the heat quickly introduced to each part of the fiber when the cigarette is heated / combusted, so that the fragrance release of each part of the fiber is more uniform.

[0038] In the above preparation method, step a) is a process of dissolving the high molecular polymer to obtain a polymer solution. In order to improve the speed and uniformity of polymer dissolution, this step is carried out under heating conditions. The above polymer is preferably a degradable polymer, and preferably one or a mixture of several of polyvinyl alcohol, polyethylene oxide, polylactic acid, and cellulose acetate; the solvent is preferably one or a mixture of several of formic acid, deionized water, ethanol, and dichloromethane; and the heating temperature is preferably 30-110°C. In order to further accelerate the dissolution speed and improve the dissolution uniformity, this step can also be carried out under stirring conditions, and the stirring speed is preferably 1000-10000 r / min. More preferably, the polymer is polylactic acid and the solvent is dichloromethane, or the polymer is polyvinyl alcohol and the solvent is deionized water. For the former, the further preferred heating temperature is 40-60°C; for the latter, the further preferred heating temperature is 60-90°C. The polymer concentration in the polymer solution obtained in this step is preferably 5-25 wt%, more preferably 10-15 wt%, and most preferably 11-13 wt%.

[0039] Step b) above is a step of mixing raw materials to prepare a spinning emulsion. In the process of dispersion mixing, the fragrance molecules are combined with graphene oxide and mesoporous silica, and the three are dispersed in the high molecular polymer and wrapped by the high molecular polymer. In order to improve the uniformity of the dispersion of the fragrance molecules, graphene oxide and mesoporous silica, this step preferably uses ultrasonic dispersion method, and the ultrasonic frequency is preferably 25 kHz. The fragrance can be one or a mixture of several of peppermint essential oil, citral essential oil, lavender essential oil, rose essential oil, sweet orange essential oil, and spice leaf essential oil. The graphene oxide can be single-layer graphene oxide or multi-layer graphene oxide. The particle size of the mesoporous silica is preferably 20 nm. The obtained fragrance / graphene oxide / mesoporous silica / polymer emulsion is the above-mentioned spinning emulsion. The weight ratio of the fragrance, graphene oxide and high molecular polymer in the spinning emulsion is preferably (12-24):(1-10):(1-10) 100. The spinning emulsion with this mixing ratio has suitable spinning performance, as well as high fragrance loading and uniformity. More preferably, the weight ratio of the fragrance, graphene oxide, mesoporous silica and high molecular polymer is (12-16):(1-3):(1-3):100, and further preferably the weight ratio of the fragrance, graphene oxide, mesoporous silica and high molecular polymer is 15:2:2:100.

[0040] The step c) is a step of preparing the composite nanofiber membrane by electrostatic emulsion spinning the spinning emulsion prepared in step b), i.e., the spinning emulsion. The electrostatic spinning method can be used to prepare a membrane composed of nanofiber to microfiber, which has a high surface area to volume ratio and high membrane porosity, which is beneficial to the full and uniform contact of the high-temperature flue gas with the slow-release fiber, thereby improving the uniformity and stability of the aroma release. The process conditions of this step are preferably as follows: the spinning voltage is 15 kV to 30 kV, the feeding rate is 0.1 mL / h to 5 mL / h, and the receiving distance is 10 cm to 35 cm. The process conditions cooperate with the ratio of the spinning emulsion to prepare a nanofiber with good spinning performance while ensuring high loading capacity and uniformity of the essence, and the prepared nanofiber has a suitable size and a large specific surface area. Most preferably, the spinning voltage is 22 kV, the feeding rate is 1 mL / h, and the receiving distance is 12 cm. The diameter of the prepared composite nanofiber membrane is preferably 10 nm to 1000 nm, and more preferably 50 nm to 1000 nm. After electrostatic spinning, a water washing and drying step is also preferably performed. The water washing and drying function is to remove the dust adsorbed on the surface of the fiber during the electrostatic spinning process.

[0041] As can be seen from the above, the composite nanofiber membrane prepared by the present application uses a high molecular polymer as a loading material, and uses graphene oxide and mesoporous silica as an essence adsorbent. The graphene oxide also serves as a heat conductor. The essence / graphene oxide / mesoporous silica / polymer emulsion is electrospun to obtain a composite nanofiber membrane. Due to the wrapping property of the polymer and the adsorption property of the graphene oxide and mesoporous silica to the essence, the diffusion of the essence molecules is limited, i.e., the locking effect of the fiber product on the essence at room temperature can be improved, and the release of the essence at room temperature is reduced. In addition, the graphene oxide has good heat conduction performance, and the graphene oxide is uniformly dispersed in the fiber, so that when the cigarette is heated / burned, the heat can be quickly introduced to each part of the fiber, making the aroma release of each part of the fiber more uniform, and finally making the essence stably stored at low temperature and slowly and uniformly released at high temperature, thereby achieving the effect of controllable release of the essence.

[0042] Another embodiment of the present application also provides a composite nanofiber membrane prepared by the method provided in the above embodiment, which uses a polymer as a loading material, and wraps essential oil, graphene oxide and mesoporous silica inside. Due to the wrapping property of the polymer and the adsorption property of graphene oxide and mesoporous silica to essential oil, the diffusion of essential oil molecules is limited, that is, the locking effect of the fiber product on essential oil at room temperature can be improved, and the release of essential oil at room temperature is reduced. In addition, graphene oxide has good thermal conductivity, and graphene oxide is uniformly dispersed in the fiber, so that when the cigarette is heated / combusted, heat can be quickly introduced to each part of the fiber, making the aroma release of each part of the fiber more uniform, and finally making the essential oil stably stored at low temperature and slowly and uniformly released at high temperature, so as to achieve the effect of controllable release of essential oil.

[0043] Another embodiment of the present application also provides a cigarette, which includes a filter stick containing the composite nanofiber membrane described above. Since the composite nanofiber membrane has the advantages described above, the cigarette accordingly has the advantages of small loss at room temperature, uniform aroma release at high temperature and balanced taste.

[0044] The technical solutions of the present application will be further described below in combination with specific embodiments:

[0045] Comparative Example 1

[0046] A PLA solution with a mass fraction of 13% was prepared, and dichloromethane was used as a solvent, and stirring was performed at 50℃ for 4h at a stirring speed of 300rpm. Then, essential oil with a relative PLA mass fraction of 15% was added to the PLA solution, and ultrasonic treatment was performed for 20min at an ultrasonic frequency of 25kHz to uniformly mix the solution, and a spinning solution was prepared. The spinning solution was poured into a liquid supply device of an electrospinning machine for spinning, and a feeding speed of about 1.0mL / min was set, a spinning distance of 15cm was set, and a voltage of 25kV was set. The composite nanofiber membrane was prepared by the above method, and was numbered as sample 1. The diameter of the prepared composite nanofiber membrane was 620nm, and a scanning electron microscope image is shown in Figure 1 .

[0047] Example 1

[0048] A PLA solution with a mass fraction of 13% was prepared using dichloromethane as the solvent. The solution was stirred at 50°C for 4 hours at a stirring speed of 300 rpm. Then, peppermint oil (15% relative to the mass fraction of PLA), GO (purchased from Dazhan Nano (Guangdong) Co., Ltd., model DZ-898, the same applies to subsequent examples), and mesoporous SiO2 (purchased from Bangrui New Materials Technology Co., Ltd., model SiO2-1, particle size below 20 nm, the same applies to subsequent examples) (2% relative to the mass fraction of PLA) were added to the PLA solution. The solution was then sonicated for 20 minutes at a frequency of 25 kHz to obtain a spinning emulsion. The spinning emulsion was poured into the liquid supply device of an electrospinning machine for spinning. The feed rate was set to 1.0 mL / min, the spinning distance to 12 cm, and the voltage to 22 kV. A composite nanofiber membrane was prepared using the above method, designated as Sample 2. The diameter of the obtained composite nanofiber membrane was 560 nm. A scanning electron microscope image is shown below. Figure 2 As shown.

[0049] Example 2

[0050] A 13% PLA solution was prepared using dichloromethane as the solvent and stirred at 50°C for 4 hours at a stirring speed of 300 rpm. Then, 15% rose essential oil (relative to PLA mass fraction), 2% GO (relative to PLA mass fraction), and 2% SiO2 (relative to PLA mass fraction) were added to the PLA solution, and the mixture was sonicated for 20 minutes at a frequency of 25 kHz to obtain a spinning emulsion. The spinning emulsion was poured into the liquid supply device of an electrospinning machine for spinning, with a feed rate of 1.0 mL / min, a spinning distance of 12 cm, and a voltage of 22 kV. A composite nanofiber membrane, designated as Sample 3, was prepared using this method. The diameter of the prepared composite nanofiber membrane was 700 nm. A scanning electron microscope image is shown below. Figure 3 As shown.

[0051] Example 3

[0052] A PVA solution with a mass fraction of 11% was prepared using deionized water as the solvent. The solution was stirred at 80°C for 3 hours at a stirring speed of 300 rpm. Then, peppermint oil (15% relative to PVA mass fraction), GO (2% relative to PVA mass fraction), and SiO2 (2% relative to PVA mass fraction) were added to the PVA solution, and the mixture was sonicated for 20 minutes at a frequency of 300 kHz to obtain a spinning emulsion. This spinning emulsion was then fed into the liquid supply device of an electrospinning machine for spinning. The feed rate was set to 1.0 mL / min, the spinning distance to 12 cm, and the voltage to 22 kV. A composite nanofiber membrane, designated as sample 4, was prepared using this method. The diameter of the prepared composite nanofiber membrane was 600 nm. A scanning electron microscope image is shown below. Figure 4 As shown.

[0053] From the above Figures 1 to 4It can be seen that the peppermint essential oil and rose essential oil can form uniform spinning emulsion with PLA and PVA, and have certain emulsion stability, and the surface smooth and uniform-thickness nanofiber can be formed by electrospinning. The addition of GO and SiO2 does not destroy the stability of the emulsion system, and has little effect on the morphology of the fiber.

[0054] The initial fragrance loadings of the above sample 1 to sample 4 are tested; the temperature rising rate is set to 3℃ / min, and the corresponding loadings at 50℃ are tested, and the test results are listed in Table 1:

[0055] Table 1 Fragrance loadings of composite nanofiber membrane

[0056] Sample 1 Sample 2 Sample 3 Sample 4 Room temperature loading 45％ 62％ 60％ 61％ 50°C loading 22％ 16％ 18％ 17％

[0057] It can be seen from Table 1 that by adding graphene oxide and mesoporous silica, the fragrance loading can be increased, and the release rate of the fragrance in a high-temperature environment can be increased.

[0058] After sample 1 to sample 4 are placed at room temperature for 30 days, the fragrance retention rates in the samples are 78%, 95%, 96% and 95% respectively. The fragrance retention rate of different samples changes with time under room temperature conditions as shown in Figure 5 It can be seen from Figure 5 that the composite nanofiber membrane prepared by the method of the application has better locking effect on the fragrance at room temperature.

[0059] The fragrance value of different samples changes with time under 50℃ conditions as shown in Figure 6 The fragrance retention rate of different samples changes with time as shown in Figure 7 Under 50℃ conditions:

[0060] Sample 1: Under 50℃ conditions, the initial fragrance value is 150, the fragrance value reaches 460 after 1min, the fragrance value is 230 after 10min, and the fragrance retention rate is 22%.

[0061] Sample 2: Under 50℃ conditions, the initial fragrance value is 120, the fragrance value reaches 525 after 1min, the fragrance value is 535 after 10min, and the fragrance retention rate is 16%.

[0062] Sample 3: Under 50℃ conditions, the initial fragrance value is 100, the fragrance value reaches 525 after 1min, the fragrance value is 530 after 10min, and the fragrance retention rate is 18%.

[0063] Sample 4: Under 50℃ conditions, the initial fragrance value is 110, the fragrance value reaches 540 after 1min, the fragrance value is 537 after 10min, and the fragrance retention rate is 17%.

[0064] Therefore, the composite nanofiber membrane prepared by the method has more balanced aroma release, and is beneficial to improving the stability of smoking taste of the cigarette.

[0065] Embodiments of the application have been described above, with the understanding that these embodiments are illustrative only and are not restrictive in nature. Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the disclosed embodiments, the application can be practiced otherwise than as specifically described. The above description is intended to be illustrative, and not restrictive. Many embodiments of the application will be apparent to an ordinarily skilled artisan upon reviewing this document. The scope of the application should, therefore, be determined not with reference to the above description, but instead with reference to the appended claims, along with their full scope of equivalents.

Claims

1. A method for preparing a composite nanofiber membrane, characterized in that, include: Step a) Add the polymer to a solvent, heat to dissolve, and obtain a polymer solution; Step b) Add fragrance, graphene oxide and mesoporous silica to the polymer solution and disperse by ultrasonication to obtain a spinning emulsion; the weight ratio of fragrance, graphene oxide, mesoporous silica and polymer is (12~16):(1~3):(1~3):

100. Step c) Electrospinning the spinning emulsion to obtain a composite nanofiber membrane.

2. The preparation method according to claim 1, characterized in that, The polymer is one or a mixture of several of the following: polyvinyl alcohol, polyethylene oxide, polylactic acid, and cellulose acetate.

3. The preparation method according to claim 2, characterized in that, The concentration of the polymer emulsion is 5wt% to 25wt%.

4. The preparation method according to claim 1, characterized in that, The fragrance is one or a mixture of several of the following: peppermint essential oil, citral essential oil, lavender essential oil, rose essential oil, sweet orange essential oil, and geranium essential oil.

5. The preparation method according to claim 1, characterized in that, In step c), the spinning voltage is set to 15kV~30kV, the liquid feeding rate is 0.1mL / h~5mL / h, and the receiving distance is 10cm~35cm.

6. The preparation method according to claim 1, characterized in that, The diameter of the composite nanofiber membrane is 100 nm to 1000 nm.

7. A composite nanofiber membrane, characterized in that, It is prepared according to the method of any one of claims 1 to 6.

8. A cigarette, characterized in that, Its filter rod contains the composite nanofiber membrane as described in claim 7.

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