Microcapsules, methods of making and using the same

Abstract

The present application relates to the field of microcapsules, in particular to a microcapsule, a preparation method and application thereof.The present application provides a preparation method of a microcapsule, comprising the following steps: (1) obtaining esterified carbon nanomaterials by esterification reaction of active group modified carbon nanomaterials; (2) obtaining esterified microcapsule wall materials by esterification reaction of first microcapsule wall materials; (3) obtaining microcapsule wall material intermediates by reaction of the esterified carbon nanomaterials, the esterified microcapsule wall materials, bismaleimide and third organic solvents; (4) obtaining the microcapsules by reaction, filtration of the microcapsule wall material intermediates, second microcapsule wall material raw materials, essence and solvents.The microcapsules obtained by the preparation method provided by the present application have effectively improved thermal conductivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microcapsules, in particular to a microcapsule and a preparation method and application thereof. BACKGROUND

[0002] Microcapsules containing aroma components are widely used for flavoring of cigarette products, reducing the irritability of cigarettes, and improving the smoking quality, which has a great market demand. However, the wall materials currently used for the preparation of such microcapsules are mainly organic molecules, which results in low thermal conductivity of the microcapsules, uneven heating of the cigarette tobacco containing aroma microcapsules, and thus insufficient release of effective components in the tobacco and aroma components in the microcapsules. Therefore, materials with high thermal conductivity (such as graphene) are proposed to be introduced into the microcapsules for improving the heating degree of the microcapsules and the tobacco. However, the problem is that such materials are physically mixed and loaded into the microcapsules, which has the problems of uneven distribution, low loading rate and uncontrollable preparation, and limited effect on improving the thermal conductivity of the microcapsules. SUMMARY

[0003] Therefore, the technical problem to be solved by the present application is to overcome the limited effect of the microcapsules containing thermal conductive materials on improving the thermal conductivity of the microcapsules in the prior art, and to provide a microcapsule and a preparation method and application thereof.

[0004] The present application provides a preparation method of a microcapsule, comprising the following steps:

[0005] (1) mixing an active group modified carbon nanomaterial, furan carboxylic acid or a derivative thereof, and a first organic solvent to perform an esterification reaction, to obtain an esterified carbon nanomaterial;

[0006] (2) mixing a first microcapsule wall material, furan carboxylic acid or a derivative thereof, and a second organic solvent to perform an esterification reaction, to obtain an esterified microcapsule wall material;

[0007] (3) mixing the esterified carbon nanomaterial, the esterified microcapsule wall material, bismaleimide, and a third organic solvent to perform a reaction, to obtain a microcapsule wall material intermediate;

[0008] (4) mixing the microcapsule wall material intermediate, a second microcapsule wall material raw material, a fragrance, and a solvent to perform a reaction, and filtering, to obtain the microcapsule.

[0009] The derivative of furan carboxylic acid includes 5-hydroxymethyl-2-furan carboxylic acid.

[0010] Preferably, the preparation method of the microcapsule comprises the following steps:

[0011] (1) mixing the active group modified carbon nanomaterial, furan carboxylic acid or its derivative and the first organic solvent to perform esterification reaction, and then performing centrifugation, water washing and filtration to obtain the esterified carbon nanomaterial;

[0012] (2) mixing the first microcapsule wall material, furan carboxylic acid or its derivative and the second organic solvent to perform esterification reaction, and then performing centrifugation, water washing and filtration to obtain the esterified microcapsule wall material;

[0013] (3) mixing the esterified carbon nanomaterial, the esterified microcapsule wall material, bismaleimide and the third organic solvent to perform reaction, and then performing centrifugation, water washing and filtration to obtain the microcapsule wall material intermediate;

[0014] (4) mixing the microcapsule wall material intermediate, the second microcapsule wall material raw material, the essence and the solvent to perform reaction, and then performing filtration to obtain the microcapsule.

[0015] Preferably, the active group modified carbon nanomaterial is a hydroxyl group modified carbon nanomaterial.

[0016] Preferably, the active group modified carbon nanomaterial is graphene oxide; or the active group modified carbon nanomaterial is obtained by acid oxidation of carbon nanomaterial.

[0017] The active group modified carbon nanomaterial is graphene oxide; or the active group modified carbon nanomaterial is obtained by acid oxidation of carbon nanomaterial.

[0018] Preferably, the step of acid oxidation of carbon nanomaterial comprises: mixing carbon nanomaterial, hydrochloric acid, nitric acid and water to perform reaction; the reaction temperature is 50-70℃, the reaction time is 12-36h; the adding ratio of the carbon nanomaterial, hydrochloric acid, nitric acid and water is (1-2) : (10-20) : (10-20) : (10-20), the ratio unit is g:ml:ml:ml.

[0019] Preferably, the concentration of the hydrochloric acid is 36%-38%.

[0020] Preferably, the concentration of the nitric acid is 68-69%.

[0021] Preferably, the particle size of the carbon nanomaterial is 5-500nm.

[0022] Preferably, the carbon nanomaterial is selected from carbonization products of biomass.

[0023] Preferably, the step of acid oxidation of carbon nanomaterial comprises: mixing carbon nanomaterial, hydrochloric acid, nitric acid and water to perform reaction, and then performing centrifugation, water washing and drying to obtain the active group modified carbon nanomaterial.

[0024] Optionally, the preparation method of the carbonized product of the biomass comprises the following steps: heating the biomass under a protective gas atmosphere at a heating rate of 1-10 ℃ / min to 600-700 ℃, maintaining for 1-2 hours, then heating at a heating rate of 1-10 ℃ / min to 800-900 ℃, maintaining for 1-2 hours, and naturally cooling to obtain the carbonized product of the biomass;

[0025] Optionally, the preparation method of the carbonized product of the biomass comprises the following steps: mixing the biomass with NiCl2·6H2O, then heating at a heating rate of 1-10 ℃ / min to 600-700 ℃ under a protective gas atmosphere, maintaining for 1-2 hours, then heating at a heating rate of 1-10 ℃ / min to 800-900 ℃, maintaining for 1-2 hours, and naturally cooling to obtain the carbonized product of the biomass;

[0026] Optionally, the protective gas is selected from one of nitrogen and inert gas;

[0027] Optionally, the mass ratio of the biomass to NiCl2·6H2O is (90-120):(0.2-1).

[0028] Preferably, the biomass is lignin.

[0029] Preferably, step (1) further comprises the step of adding a catalyst to the reaction solution.

[0030] The adding ratio of the active group modified carbon nanomaterial, the furan carboxylic acid or its derivative, the first organic solvent, and the catalyst is (1-2):(0.5-1):(10-30):(0.1-0.2), and the unit of the ratio is g: g: ml: ml.

[0031] The reaction temperature is 100-120 ℃, and the reaction time is 14-16 h.

[0032] The first organic solvent is toluene.

[0033] The catalyst is sulfuric acid, and preferably, the concentration of the sulfuric acid is 98-99%.

[0034] Preferably, step (2) further comprises the step of adding a catalyst to the reaction solution.

[0035] The adding ratio of the first microcapsule wall material, the furan carboxylic acid or its derivative, the second organic solvent, and the catalyst is (1-2):(0.5-1):(10-30):(0.1-0.2), and the unit of the ratio is g: g: ml: ml.

[0036] The reaction temperature is 100-120 ℃, and the reaction time is 14-16 h.

[0037] The second organic solvent is toluene;

[0038] The catalyst is sulfuric acid, preferably, the concentration of the sulfuric acid is 98-99%;

[0039] Preferably, the first microcapsule wall material is selected from compounds containing hydroxyl functional groups.

[0040] Preferably, the first microcapsule wall material is selected from at least one of beta-cyclodextrin, chitosan, gum arabic.

[0041] Preferably, in step (3), the addition ratio of the esterified carbon nanomaterial, the esterified microcapsule wall material, the bismaleimide and the third organic solvent is (0.9-1.1) :(0.9-1.1) :(0.4-0.6) :(10-30), the ratio unit is g: g: g: ml;

[0042] In step (3), the reaction temperature is 50-70℃, and the reaction time is 10-14h;

[0043] Preferably, the third organic solvent is selected from tetrahydrofuran;

[0044] Preferably, the general structure of the bismaleimide is:

[0045]

[0046] Wherein, R1-R4 are each independently selected from hydrogen, C1-C10 alkyl, and R is selected from C1-C6 alkylene;

[0047] Preferably, R1-R4 are selected from hydrogen; and R is selected from ethylene.

[0048] Preferably, in step (4), the mass ratio of the microcapsule wall material intermediate, the essence, the second microcapsule wall material raw material and the solvent is (0.02-0.5) :(0.1-0.5) :(1-2) :(20-40); the reaction temperature is 40-65℃, and the reaction time is 3-6h;

[0049] Preferably, the solvent is water;

[0050] Preferably, in step (4), the second microcapsule wall material raw material is selected from at least one of beta-cyclodextrin, chitosan, gum arabic; and the essence is selected from one of menthol, apple essence, lemon essence.

[0051] The application provides a microcapsule prepared by the preparation method.

[0052] The application provides application of the microcapsule in a cigarette product.

[0053] The technical scheme of the present application has the following advantages:

[0054] The preparation method of the microcapsule provided by the present application comprises the following steps: (1) mixing active group modified carbon nanomaterials with furan carboxylic acid or its derivatives to perform esterification reaction, to obtain esterified carbon nanomaterials; (2) mixing first microcapsule wall materials with furan carboxylic acid or its derivatives to perform esterification reaction, to obtain esterified microcapsule wall materials; (3) mixing the esterified carbon nanomaterials, the esterified microcapsule wall materials, bismaleimide and an organic solvent to perform reaction, to obtain microcapsule wall material intermediates; (4) mixing the microcapsule wall material intermediates, second microcapsule wall material raw materials, essence and a solvent to perform reaction, and filtering, to obtain the microcapsule.

[0055] The active group modified carbon nanomaterials and the first microcapsule wall material raw materials have reaction groups and can be mixed with furan carboxylic acid or its derivatives to perform esterification reaction, to obtain esterified carbon nanomaterials and esterified microcapsule wall materials respectively; the esterified carbon nanomaterials have better dispersibility than the carbon nanomaterials; the esterified carbon nanomaterials and the esterified microcapsule wall materials perform reaction (Diels-Alder (4+2) addition reaction) with bismaleimide, to obtain a complex of maleimide furan groups connecting carbon nanomaterials and the first microcapsule wall materials (i.e. microcapsule wall material intermediates); the microcapsule wall material intermediates, essence, second microcapsule wall material raw materials and a solvent are mixed to perform reaction, to obtain the microcapsule; the carbon nanomaterials in the complex of maleimide furan groups connecting carbon nanomaterials and the first microcapsule wall materials are more stably combined with the matrix, so as to reduce the interfacial thermal resistance and improve the overall thermal conductivity of the material; in addition, the carbon nanomaterials in the complex of maleimide furan groups connecting carbon nanomaterials and the first microcapsule wall materials are uniformly distributed in the wall material matrix, which also helps to improve the thermal conductivity of the microcapsule;

[0056] In summary, the microcapsule obtained by the preparation method provided by the present application has effectively improved thermal conductivity;

[0057] Further, the complex of maleimide furan groups connecting carbon nanomaterials and the first microcapsule wall materials formed by Diels-Alder (4+2) addition reaction will undergo reverse Diels-Alder ring-opening reaction at about 100-150℃, so as to make the microcapsule wall of the complex collapse, so as to realize accurate release of the fragrance material coated by the microcapsule within a certain temperature range;

[0058] Further, since the combination of the carbon nanomaterial and the matrix in the complex of the maleimide furan group connecting the carbon nanomaterial and the first microcapsule wall material is more stable, the carbon nanomaterial with high thermal conductivity is not easy to precipitate during use, reducing the adverse effects of carbon nanomaterial precipitation on human health. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0060] Figure 1 Transmission electron microscopy particle size characterization diagram of graphene oxide used in the examples and comparative examples of the present application;

[0061] Figure 2 Scanning electron microscope macroscopic morphology diagram of the carbon nanomaterial uniformly distributed microcapsules prepared in Example 1 of the present application;

[0062] Figure 3 Scanning electron microscope micro-morphology diagram of the carbon nanomaterial uniformly distributed microcapsules prepared in Example 1 of the present application;

[0063] Figure 4 Fourier transform infrared spectrogram of the carbon nanomaterial uniformly distributed microcapsules prepared in Example 1 of the present application;

[0064] Figure 5 Thermogravimetric (TG), differential scanning calorimetry curve (DSC), and derivative thermogravimetric analysis curve (DTG) of the carbon nanomaterial uniformly distributed microcapsules prepared in Example 1 of the present application;

[0065] Figure 6 Low-magnification transmission electron micrograph of the complex of the maleimide furan group connecting graphene oxide and β-cyclodextrin in Example 1 of the present application. DETAILED DESCRIPTION

[0066] The following examples are provided to better further understand the present application and are not limited to the best mode, and do not constitute a limitation on the content and scope of protection of the present application. Any person under the inspiration of the present application or the combination of the present application with other prior art features can obtain any product identical or similar to the present application, which falls within the scope of protection of the present application.

[0067] The specific experimental steps or conditions are not indicated in the examples, which can be carried out according to the conventional experimental steps or conditions described in the literature in the art. The reagents or instruments used are not indicated by the manufacturer, which are conventional reagent products that can be obtained by purchase.

[0068] The active group modified carbon nanomaterial used in the examples and comparative examples of the present application is graphene oxide (particle size characterization as shown in Figure 1 The graphene oxide used in the examples and comparative examples of the present application is purchased from aladdin company, model G139803;

[0069] The β-cyclodextrin used in the examples and comparative examples of the present application is purchased from macklin company, model: C11993584;

[0070] The menthol used in the examples and comparative examples of the present application is purchased from macklin company, model: 218-690-9;

[0071] The lignin used in examples 2 and 3 of the present application is purchased from macklin company, product number: L832292.

[0072] Example 1

[0073] The present example provides a preparation method of microcapsules, comprising the following steps:

[0074] (1) 1g of graphene oxide and 0.5g of furan carboxylic acid are placed in 20ml of toluene, 0.1ml of sulfuric acid with a concentration of 98.3% is added as a catalyst to carry out esterification reaction, and then centrifugation, water washing and drying are carried out to obtain esterified graphene oxide, wherein the esterification reaction temperature is 110℃, and the esterification reaction time is 16h;

[0075] (2) 1g of β-cyclodextrin and 0.5g of furan carboxylic acid are placed in 20ml of toluene, 0.1ml of sulfuric acid with a concentration of 98.3% is added as a catalyst to carry out esterification reaction, and then centrifugation, water washing and drying are carried out to obtain esterified β-cyclodextrin, wherein the esterification reaction temperature is 110℃, and the esterification reaction time is 16h;

[0076] (3) 1g of esterified graphene oxide prepared in step (1), 1g of esterified β-cyclodextrin prepared in step (2), and 0.5g of 1,2-dimalimide ethane are dispersed in 20ml of tetrahydrofuran to carry out Diels-Alder (4+2) addition reaction at 60℃ for 12h, and then centrifugation, water washing and drying are carried out to obtain a complex of maleimide furan group connected with graphene oxide and β-cyclodextrin (i.e. microcapsule wall material intermediate);

[0077] (4) 100 mg of the maleimide furan group connected graphene oxide and β-cyclodextrin complex prepared in step (3), 1 g of menthol, 3 g of β-cyclodextrin were dissolved in 50 ml of water, and reacted at 50°C for 4 h. After filtration, the microcapsules were obtained.

[0078] The obtained microcapsules with uniform distribution of carbon nanomaterials were analyzed in terms of morphology, infrared spectrum, particle size, and thermodynamic properties.

[0079] Figure 2 The scanning electron microscope macroscopic morphology of the microcapsules is shown in Figure 1.

[0080] Figure 3 The scanning electron microscope micro-morphology of the microcapsules is shown in Figure 2.

[0081] Figure 4 The Fourier transform infrared spectrum of the microcapsules is shown in Figure 3.

[0082] Figure 5 The thermogravimetric (TG), differential scanning calorimetry (DSC), and derivative thermogravimetric analysis (DTG) curves of the microcapsules are shown in Figure 4. The TG ordinate is mass fraction (%), the DSC curve ordinate is heat flow rate (mW / mg), and the DTG curve ordinate is weight loss rate (mg / min). The test temperature ramp rate of TG and DSC is 10°C / min.

[0083] Figure 6 The low magnification transmission electron micrograph of the maleimide furan group connected graphene oxide and β-cyclodextrin complex is shown in Figure 5.

[0084] Example 2

[0085] The present embodiment provides a method for preparing microcapsules, comprising the following steps:

[0086] (1) 100 g of lignin was placed in a tube furnace and heated to 600°C at a rate of 3°C / min under a nitrogen atmosphere. After holding for 1 hour, the temperature was increased to 900°C at a rate of 2°C / min. After holding for 2 hours, the carbonized product of lignin (particle size 5-500 nm) was obtained.

[0087] (2) 10 g of the carbonized lignin obtained in step (1) was mixed with 166 ml of 37% concentrated hydrochloric acid, 166 ml of 68% concentrated nitric acid, and 166 ml of water. The mixture was subjected to an oxidation reaction at 60°C for 24 hours. After centrifugation, water washing, and drying, the hydroxyl-modified carbonized product of lignin was obtained.

[0088] (3) 1 g of the carbonized product of hydroxyl-modified lignin obtained in step (2) and 0.5 g of furan carboxylic acid were placed in 20 ml of toluene, and 0.1 ml of sulfuric acid having a concentration of 98.3% was added as a catalyst to perform esterification, followed by centrifugation, water washing, and drying, thereby obtaining the carbonized product after esterification, wherein the esterification temperature was 110°C, and the esterification time was 16 h;

[0089] (4) 1 g of β-cyclodextrin and 0.5 g of furan carboxylic acid were placed in 20 ml of toluene, and 0.1 ml of sulfuric acid having a concentration of 98.3% was added as a catalyst to perform esterification, followed by centrifugation, water washing, and drying, thereby obtaining the β-cyclodextrin after esterification, wherein the esterification temperature was 110°C, and the esterification time was 16 h;

[0090] (5) 1 g of the carbonized product after esterification prepared in step (3), 1 g of the β-cyclodextrin after esterification prepared in step (4), and 0.5 g of 1,2-dimalimide ethane were dispersed in 20 ml of tetrahydrofuran to perform Diels-Alder (4+2) addition reaction at 60°C for 12 h, followed by centrifugation, water washing, and drying, thereby obtaining a complex of the carbonized product and the β-cyclodextrin to which maleimide furan groups were attached;

[0091] (6) 100 mg of the complex of the carbonized product and the β-cyclodextrin to which maleimide furan groups were attached prepared in step (3), 1 g of menthol, and 3 g of β-cyclodextrin were dissolved in 50 ml of water, and the mixture was reacted at 50°C for 4 h, followed by filtration, thereby obtaining the microcapsule.

[0092] Example 3

[0093] The present embodiment provides a method for preparing a microcapsule, comprising the following steps:

[0094] (1) 100 g of lignin and 0.5 g of NiCl2·6H2O were mixed by grinding with a mortar, and then placed in a tube furnace, and heated to 600°C at a temperature increasing rate of 3°C / min under a nitrogen atmosphere, and then heated to 900°C at a temperature increasing rate of 2°C / min after maintaining the temperature for 1 h, and then maintained the temperature for 2 h, thereby obtaining a carbonized product of lignin (having a particle size of 5-500 nm);

[0095] (2) 10 g of the carbonized product of lignin obtained in step (1), 166 ml of hydrochloric acid having a concentration of 37%, 166 ml of nitric acid having a concentration of 68%, and 166 ml of water were mixed, and then subjected to an oxidation reaction at 60°C for 24 h, followed by centrifugation, water washing, and drying, thereby obtaining a carbonized product of hydroxyl-modified lignin;

[0096] (3) 1 g of the carbonized product of the hydroxyl-modified lignin obtained in step (2) and 0.5 g of furan carboxylic acid were placed in 20 ml of g-toluene, 0.1 ml of 98.3% sulfuric acid was added as a catalyst for esterification, and then centrifugation, water washing, and drying were performed to obtain the esterified carbonized product, wherein the esterification temperature was 110°C and the esterification time was 16 h;

[0097] (4) 1 g of β-cyclodextrin and 0.5 g of furan carboxylic acid were placed in 20 ml of g-toluene, 0.1 ml of 98.3% sulfuric acid was added as a catalyst for esterification, and then centrifugation, water washing, and drying were performed to obtain the esterified β-cyclodextrin, wherein the esterification temperature was 110°C and the esterification time was 16 h;

[0098] (5) 1 g of the esterified carbonized product prepared in step (3), 1 g of the esterified β-cyclodextrin prepared in step (4), and 0.5 g of 1,2-dimalimide ethane were dispersed in 20 ml of g-tetrahydrofuran and subjected to Diels-Alder (4+2) addition reaction at 60°C for 12 h, and then centrifugation, water washing, and drying were performed to obtain a complex of the carbonized product and the β-cyclodextrin to which a maleimide furan group was attached;

[0099] (6) 100 mg of the complex of the carbonized product and the β-cyclodextrin to which a maleimide furan group was attached prepared in step (3), 1 g of menthol, and 3 g of β-cyclodextrin were dissolved in 50 ml of water and reacted at 50°C for 4 h, and then filtration was performed to obtain the microcapsule.

[0100] Comparative Example 1

[0101] The present comparative example provides a method for preparing a microcapsule, comprising the following steps:

[0102] (1) 1 g of β-cyclodextrin and 0.5 g of furan carboxylic acid were placed in 20 ml of g-toluene, 0.1 ml of 98.3% sulfuric acid was added as a catalyst for esterification, and then centrifugation, water washing, and drying were performed to obtain the esterified β-cyclodextrin, wherein the esterification temperature was 110°C and the esterification time was 16 h;

[0103] (2) 1 g of graphene oxide, 1 g of the esterified β-cyclodextrin prepared in step (1), and 0.5 g of 1,2-dimalimide ethane were dispersed in 20 ml of tetrahydrofuran and subjected to Diels-Alder (4+2) addition reaction at 60°C for 12 h, and then centrifugation, water washing, and drying were performed to obtain a microcapsule wall material intermediate;

[0104] (3) 100 mg of the microcapsule wall material intermediate prepared in step (2), 1 g of menthol, and 3 g of β-cyclodextrin were dissolved in 50 ml of water, and the mixture was reacted at 50°C for 4 h. After filtration, the microcapsule was obtained.

[0105] Comparative Example 2

[0106] The present comparative example provides a method for preparing a microcapsule, comprising the following steps:

[0107] (1) 1 g of graphene oxide and 0.5 g of furan carboxylic acid were placed in 20 ml of toluene, and 0.1 ml of sulfuric acid with a concentration of 98.3% was added as a catalyst for esterification reaction. After centrifugation, water washing, and drying, the esterified graphene oxide was obtained, wherein the esterification reaction temperature was 110°C, and the esterification reaction time was 16 h;

[0108] (2) 1 g of the esterified graphene oxide prepared in step (1), 1 g of β-cyclodextrin, and 0.5 g of 1,2-dimalimide ethane were dispersed in 20 ml of tetrahydrofuran, and a Diels-Alder (4+2) addition reaction was performed at 60°C for 12 h. After centrifugation, water washing, and drying, the microcapsule wall material intermediate was obtained;

[0109] (3) 100 mg of the microcapsule wall material intermediate prepared in step (2), 1 g of menthol, and 3 g of β-cyclodextrin were dissolved in 50 ml of water, and the mixture was reacted at 50°C for 4 h. After filtration, the carbon microcapsule was obtained.

[0110] Comparative Example 3

[0111] The present comparative example provides a method for preparing a microcapsule, comprising the following steps:

[0112] (1) 1 g of graphene oxide and 0.5 g of furan carboxylic acid were placed in 20 ml of toluene, and 0.1 ml of sulfuric acid with a concentration of 98.3% was added as a catalyst for esterification reaction. After centrifugation, water washing, and drying, the esterified graphene oxide was obtained, wherein the esterification reaction temperature was 110°C, and the esterification reaction time was 16 h;

[0113] (2) 1 g of β-cyclodextrin and 0.5 g of furan carboxylic acid were placed in 20 ml of toluene, and 0.1 ml of sulfuric acid with a concentration of 98.3% was added as a catalyst for esterification reaction. After centrifugation, water washing, and drying, the esterified β-cyclodextrin was obtained, wherein the esterification reaction temperature was 110°C, and the esterification reaction time was 16 h;

[0114] (3) 1 g of the esterified graphene oxide prepared in step (1), 1 g of the esterified β-cyclodextrin prepared in step (2), and were dispersed in 20 ml of tetrahydrofuran, and the mixture was treated at 60°C for 12 h to obtain a microcapsule wall material intermediate.

[0115] (4) 100 mg of the microcapsule wall material intermediate prepared in step (3), 1 g of menthol, and 3 g of β-cyclodextrin were dissolved in 50 ml of water, and reacted at 50°C for 4 h. After filtration, the microcapsule was obtained.

[0116] Comparative Example 4

[0117] The present comparative example provides a method for preparing a microcapsule, comprising the following steps: 50 mg of graphene oxide, 1 g of menthol, and 3.05 g of β-cyclodextrin were dissolved in 50 ml of water, and reacted at 50°C for 4 h. After filtration, the microcapsule was obtained.

[0118] Test Example

[0119] Thermal conductivity test

[0120] The thermal conductivities of the microcapsules prepared in the examples and comparative examples were tested by the Hot Disk method / transient plane heat source method, and the results are shown in Table 1.

[0121] Table 1

[0122]

[0123] Obviously, the above examples are merely examples for the purpose of clarity, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can also be made by those of ordinary skill in the art. It is not necessary or possible to exhaust all embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for preparing microcapsules, characterized in that, The method comprises the following steps: (1) mixing the active group modified carbon nanomaterial, furan carboxylic acid or its derivative and a first organic solvent to perform an esterification reaction, to obtain an esterified carbon nanomaterial; (2) mixing the first microcapsule wall material, furan carboxylic acid or its derivative and a second organic solvent to perform an esterification reaction, to obtain an esterified microcapsule wall material; (3) mixing the esterified carbon nanomaterial, the esterified microcapsule wall material, bismaleimide and a third organic solvent to perform a reaction, to obtain a microcapsule wall material intermediate; (4) mixing the microcapsule wall material intermediate, a second microcapsule wall material raw material, a fragrance and a solvent to perform a reaction, and filtering, to obtain the microcapsule. The active group modified carbon nanomaterial is a hydroxyl group modified carbon nanomaterial. The first microcapsule wall material is selected from a compound containing a hydroxyl functional group. In step (4), the second microcapsule wall material raw material is selected from at least one of β-cyclodextrin, chitosan and gum arabic.

2. The production method according to claim 1, characterized by, The active group modified carbon nanomaterial is graphene oxide; or the active group modified carbon nanomaterial is obtained after acid oxidation of the carbon nanomaterial.

3. The production method according to claim 2, characterized by, The step of acid oxidation of the carbon nanomaterial comprises mixing the carbon nanomaterial, hydrochloric acid, nitric acid and water to perform a reaction; the reaction temperature is 50-70°C, and the reaction time is 12-36h; the addition ratio of the carbon nanomaterial, hydrochloric acid, nitric acid and water is (1-2):(10-20):(10-20):(10-20), the ratio unit being g:ml:ml:ml.

4. The production method according to claim 3, characterized by, The concentration of the hydrochloric acid is 36%-38%.

5. The preparation method according to claim 3, characterized in that, The concentration of the nitric acid is 68-69%.

6. The preparation method according to claim 3, characterized in that, The particle size of the carbon nanomaterial is 5-500 nm.

7. The preparation method according to claim 4, characterized in that, The carbon nanomaterial is selected from a carbonization product of biomass.

8. The preparation method according to claim 7, characterized in that, The biomass is lignin.

9. The method of claim 1, wherein, In step (1), a step of adding a catalyst to the reaction solution is further included. The addition ratio of the active group modified carbon nanomaterial, furan carboxylic acid or its derivative, the first organic solvent and the catalyst is (1-2):(0.5-1):(10-30):(0.1-0.2), the ratio unit being g:g:ml:ml; The reaction temperature is 100-120°C, and the reaction time is 14-16h; The first organic solvent is toluene; The catalyst is sulfuric acid.

10. The method of claim 9, wherein, The concentration of the sulfuric acid is 98-99%.

11. The method of claim 1, wherein, In step (2), a step of adding a catalyst to the reaction solution is further included. The addition ratio of the first microcapsule wall material, furan carboxylic acid or its derivative, the second organic solvent and the catalyst is (1-2):(0.5-1):(10-30):(0.1-0.2), the ratio unit being g:g:ml:ml; The reaction temperature is 100-120°C, and the reaction time is 14-16h; The second organic solvent is toluene; The catalyst is sulfuric acid.

12. The method of claim 11, wherein, The concentration of the sulfuric acid is 98-99%.

13. The method of claim 1, wherein, The first microcapsule wall material is selected from at least one of β-cyclodextrin, chitosan and gum arabic.

14. The method of claim 1, wherein, In step (3), the adding ratio of the esterified carbon nanomaterial, the esterified microcapsule wall material, the bismaleimide and the third organic solvent is (0.9-1.1):(0.9-1.1):(0.4-0.6):(10-30) g: g: g: ml. In step (3), the reaction temperature is 50-70℃, and the reaction time is 10-14 h.

15. The method of claim 14, wherein, The third organic solvent is selected from tetrahydrofuran.

16. The method of claim 14, wherein, The general structure of the bismaleimide is: wherein R1-R4 are independently selected from hydrogen, C1-C10 alkyl, and R is selected from C1-C6 alkylene.

17. The method of claim 16, wherein, R1-R4 are selected from hydrogen, and R is selected from ethylene.

18. The method of claim 1, wherein, In step (4), the mass ratio of the microcapsule wall material intermediate, the essence, the second microcapsule wall material raw material and the solvent is (0.02-0.5):(0.1-0.5):(1-2):(20-40), the reaction temperature is 40-65℃, and the reaction time is 3-6 h.

19. The method of claim 18, wherein, The solvent is water.

20. The method of claim 18, wherein, The essence is selected from one of menthol, apple essence and lemon essence.

21. A microcapsule characterized in that, The microcapsule is prepared by the preparation method of any one of claims 1-20, and the thermal conductivity of the microcapsule is (0.30-0.45) W / (m•k).

22. The microcapsule of claim 21 is applied in a cigarette product.

Images