Microcapsules and composite fibers prepared therewith

Abstract

This invention discloses a microcapsule and a composite fiber prepared therefrom. The microcapsule comprises aerogel particles loaded with essential oils and a skin layer covering the aerogel particles, the skin layer being an organosilicon film. Utilizing the porous nature of the aerogel particles, aromatic essential oils are loaded under negative pressure. Then, a negatively charged surfactant is used to make the surface of the aerogel particles negatively charged, followed by the adsorption of amino silicone oil and the addition of epoxy-modified silicone oil. The high reactivity of the amino-epoxy groups allows the amino silicone oil and epoxy-modified silicone oil to react, thereby forming an organosilicon film on the surface of the aerogel particles. This formed organosilicon film encapsulates the porous aerogel particles. This microcapsule not only possesses a long-lasting and uniform aroma release function but also exhibits excellent mechanical and chemical stability, which is beneficial for preparing composite fibers and their products with aroma release function.

Description

[0001] This invention is a divisional application of Chinese invention patent application filed on October 25, 2023, with application number 2023113910004 and titled "A microcapsule and its preparation method and composite fiber". Technical Field

[0002] This invention relates to the field of microcapsules, and more particularly to microcapsules with a long-lasting and uniform aroma sustained-release function and composite fibers containing the microcapsules, specifically to a microcapsule and composite fibers prepared therefrom. Background Technology

[0003] With improved living standards and changing lifestyles, people desire improvements in the slow-release and volatile substance control functions of existing textiles. This has led to the development of slow-release functional fibers with aromatic, mosquito-repellent, and antibacterial effects. Aromatic slow-release fibers and related textiles are particularly popular with consumers. Some aromatic substances not only enhance appearance, relieve fatigue, and improve image, but also possess disinfecting, antibacterial, anti-inflammatory, and analgesic properties. Aromatic fibers are made by loading aromatic substances onto fibers or textiles through finishing processes such as impregnation and microencapsulation. However, impregnated aromatic substances are highly volatile, release rapidly, and have poor durability. Microencapsulation, on the other hand, encapsulates the aromatic substances to prevent rapid release, thus achieving slow release and longer-lasting effects. Therefore, microencapsulation of aromatic substances is currently a commonly used method.

[0004] Currently, there are two main methods for using microencapsulated aromatic substances (such as aromatic essential oil microcapsules) in the preparation of aromatic textiles:

[0005] (1) Using microcapsule fragrance finishing technology, aromatic essential oil microcapsules are adhered to fibers through post-finishing methods to make aromatic fibers, and then aromatic textiles are prepared.

[0006] (2) Add aromatic essential oil microcapsules to the spinning solution and spin them into aromatic fibers by blending, composite spinning and other methods, and then make aromatic textiles.

[0007] Theoretically, method (2) is relatively better in terms of the persistence of sustained release of aromatic essential oils because the aromatic essential oil microcapsules are located in the fiber, reducing the microcapsule shedding caused by friction during washing or wearing. However, the microcapsule wall material (or shell material) currently commonly used is a layer of polymer membrane, which has poor mechanical stability and is prone to breakage due to compression deformation during fiber forming and textile processing. However, the spinning process not only involves high temperature, but also requires high heat resistance of the wall material. In particular, the spinning pressure is high, so it is difficult to avoid the wall material being squeezed, which places high demands on the spinning process. Based on this, there are also schemes that use inorganic materials as wall materials to improve mechanical properties and shape stability, such as using silica as the shell layer. However, on the one hand, it is not easy to obtain a highly dense shell layer when preparing silica shell layer. On the other hand, since the shell is an inorganic material, its dispersion stability in the spinning solution is poor, which is not conducive to spinning high-quality fibers. In addition, the existing aromatic essential oil microcapsules have insufficient release persistence and uneven release (the release is high and fast in the early stage, and low and slow in the middle and late stages). Summary of the Invention

[0008] The purpose of this invention is to overcome one or more shortcomings in the prior art and provide a novel microcapsule that not only has a long-lasting and uniform aroma sustained-release function, but also has excellent mechanical and chemical stability.

[0009] The present invention also provides a composite fiber comprising the aforementioned microcapsules dispersed in a fiber matrix.

[0010] To achieve the above objectives, the present invention provides a technical solution: a method for preparing microcapsules, the method comprising:

[0011] Silica aerogel particles with a porous structure are added to a container, and a vacuum is drawn to a negative pressure condition. Then, aromatic essential oils are added to the container. After the aromatic essential oils penetrate into the porous structure of the silica aerogel particles, they are taken out, washed, and the aerogel particles loaded with essential oils are obtained.

[0012] The aerogel particles loaded with essential oil are mixed with a surfactant to obtain a first intermediate aerogel particle, the surface of which is adsorbed with the surfactant; wherein, after the surfactant is ionized in water, some of the groups that play a surface-active role are negatively charged.

[0013] The first intermediate aerogel particles and amino silicone oil are mixed to obtain a second intermediate aerogel particles, the surface of which is coated with the amino silicone oil.

[0014] The second intermediate aerogel particles and epoxy-modified silicone oil are mixed and reacted at 40-60°C to generate the microcapsules.

[0015] According to some preferred aspects of the present invention, the particle size of the silica aerogel particles is preferably controlled to be 0.5-10 μm, and the porosity is 65%-95%. If the particle size is less than 0.5 μm, the pore structure is too small, which is not conducive to loading. If the particle size is greater than 10 μm, it will be not conducive to the preparation of composite fibers, resulting in the microcapsule size in the composite fibers being too large, and phenomena such as protrusions appearing. High porosity is conducive to improving the loading capacity, while too low porosity is not conducive to controlling the loading capacity.

[0016] Furthermore, the particle size of the silica aerogel particles is 1-5 μm.

[0017] Furthermore, the porosity of the silica aerogel particles is 85%-95%.

[0018] According to some preferred aspects of the present invention, the negative pressure condition satisfies a relative vacuum degree of -0.1 to -0.04 MPa.

[0019] According to some preferred aspects of the present invention, the mass ratio of the aromatic essential oil to the silica aerogel particles is 0.5-10:1.

[0020] According to some preferred aspects of the invention, the washing is performed using water during the preparation of the oil-loaded aerogel particles.

[0021] According to some preferred aspects of the invention, the washing is carried out under normal pressure during the preparation of the oil-loaded aerogel particles.

[0022] According to some preferred aspects of the present invention, the surfactant is added in the form of an aqueous surfactant solution, the amino silicone oil is added in the form of an aqueous amino silicone oil solution, and the epoxy modified silicone oil is added in the form of an aqueous epoxy modified silicone oil solution.

[0023] The mass percentage concentrations of the surfactant aqueous solution, the amino silicone oil aqueous solution, and the epoxy modified silicone oil aqueous solution are 0.1%-5.0%, respectively. Controlling their concentrations helps to ensure that the skin layer formed during the preparation process has an ideal thickness and helps to control the release rate of aromatic substances.

[0024] The ratios of the mass of the oil-loaded aerogel particles to the volume of the surfactant aqueous solution, the ratio of the mass of the first intermediate aerogel particles to the volume of the amino silicone oil aqueous solution, and the ratio of the mass of the second intermediate aerogel particles to the volume of the epoxy-modified silicone oil aqueous solution, in g / mL, are 0.005-0.05, respectively.

[0025] According to some preferred aspects of the present invention, the surfactant is one or more selected from sodium polyoxyethylene dodecyl ether sulfate, sodium oleate, and sodium rosinate.

[0026] According to some preferred and specific aspects of the present invention, the amino silicone oil has the following structural formula:

[0027] In formula (Ⅰ): R0 is a hydrocarbon group or a hydrocarbon oxygen group, and R1 is a C group. 1-6 Alkylene, n and m independently range from 1 to 200.

[0028] In some preferred embodiments of the present invention, the amino silicone oil has an ammonia value of 0.3-0.6 mmol / g.

[0029] According to some preferred aspects of the present invention, the epoxy-modified silicone oil has the following structural formula:

[0030] In formula (II): R2 is a hydrocarbon group or hydrocarbon group, R3 is a C1-6 alkylene group, and a and b are independently 1-200.

[0031] In some preferred embodiments of the present invention, the reaction time between the second intermediate aerogel particles and the epoxy-modified silicone oil is controlled to be 5-60 min.

[0032] In some preferred embodiments of the present invention, the preparation of the microcapsules includes:

[0033] Silica aerogel particles with a porous structure are added to a container, and the container is evacuated to a negative pressure condition. Then, aromatic essential oils are added dropwise to the container and left to stand until the aromatic essential oils penetrate into the porous structure of the silica aerogel particles. Then, the container is removed, mixed with water under normal pressure, stirred, and filtered to obtain aerogel particles loaded with essential oils.

[0034] The aerogel particles loaded with essential oil were added to an aqueous solution of surfactant, stirred and dispersed, filtered, washed with water, and filtered again to obtain the first intermediate aerogel particles.

[0035] The first intermediate aerogel particles were added to an amino silicone oil aqueous solution, stirred and dispersed, filtered, washed with water, and filtered again to obtain the second intermediate aerogel particles.

[0036] The second intermediate aerogel particles were added to an epoxy-modified silicone oil aqueous solution, reacted, and filtered to obtain the microcapsules.

[0037] Another technical solution provided by the present invention: a microcapsule, wherein the microcapsule is prepared by the microcapsule preparation method described above.

[0038] Another technical solution provided by the present invention: a composite fiber, the composite fiber comprising a fiber matrix and aromatic sustained-release capsules dispersed in the fiber matrix, the aromatic sustained-release capsules comprising the microcapsules described above.

[0039] According to some preferred aspects of the invention, the fiber matrix is ​​modal fiber;

[0040] The method for preparing the composite fiber includes:

[0041] The aromatic sustained-release capsules are dispersed in modal spinning solution, and then the composite fiber is obtained by wet spinning modal fibers using a known method and post-treatment. During the post-treatment process, the desulfurization bath temperature and the water washing bath temperature are controlled to be less than 60°C, which helps to prevent excessive volatilization of aromatic essential oils at high temperatures.

[0042] In some preferred embodiments of the present invention, the amount of the aromatic sustained-release capsules added accounts for 3%-12% of the solute mass of the modal spinning solution by weight, which is beneficial to ensure that the composite fiber has a sufficient amount of aromatic substances. Further, the amount of the aromatic sustained-release capsules added accounts for 5%-10% of the solute mass of the modal spinning solution by weight.

[0043] In some preferred embodiments of the present invention, the post-treatment process is controlled such that the desulfurization bath temperature is 45-60°C and the water washing bath temperature is 45-60°C.

[0044] The basic principle of this invention for preparing microcapsules is as follows: Utilizing the porous (honeycomb-like) characteristics of aerogel particles, aromatic essential oils are loaded under negative pressure. Then, an organosilicon film is used to encapsulate the aerogel particles with open surfaces, thereby reducing the release rate of aromatic substances. Furthermore, a negatively charged surfactant is first used to make the surface of the aerogel particles loaded with aromatic essential oils negatively charged. Then, amino silicone oil (the presence of amino groups allows it to carry a positive charge) is adsorbed. The high reactivity of the amino-epoxy groups allows the amino silicone oil and epoxy-modified silicone oil to react, thereby forming a film on the surface of the aerogel particles, achieving the goal of forming an effective skin layer on the surface of the aerogel particles loaded with aromatic essential oils.

[0045] Furthermore, the microcapsules with long-lasting and uniform aroma sustained-release function prepared above are used to be mixed with polymers and spun to prepare composite fibers with aroma sustained-release function.

[0046] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0047] This invention addresses the shortcomings of existing aromatic essential oil microcapsules, such as poor mechanical stability, high requirements for spinning processes, and inconsistent and unsustainable release. It innovatively uses commercially available silica aerogel particles as a carrier. By expelling air from the silica aerogel particles through negative pressure, the aromatic essential oil can penetrate into the pore structure of the silica aerogel particles under negative pressure, achieving a high loading rate. Even after the negative pressure is removed, the tiny pores of the silica aerogel particles effectively lock the aromatic essential oil inside, allowing it to evaporate only through the pores. This achieves high loading of the aromatic essential oil while simultaneously reducing the evaporation rate.

[0048] Furthermore, the present invention forms an organosilicon film as a skin layer on the silica aerogel particles using a specific method, which can encapsulate the silica aerogel particles with open surfaces. This not only reduces the release rate of the loaded aromatic essential oils, but also, unexpectedly, ensures that the release rate is basically uniform.

[0049] Meanwhile, the presence of silica aerogel particles with rigid properties can also act as a mechanical filling structure inside the organosilicon film, giving the overall microcapsule particles high mechanical stability and preventing the destruction of the overall microcapsule structure during compression; the coexistence of organosilicon film and silica aerogel particles also gives the whole body good chemical stability, making it less susceptible to chemical reactivity, erosion, etc.

[0050] In addition, using commercially available silica aerogel particles as a carrier is low-cost and readily available, which greatly shortens the production process and reduces the difficulty of production; moreover, the size of silica aerogel particles is very easy to control, and they can be purchased as needed in the market, thereby allowing for stable control of the overall size of the microcapsules to match the fiber size. Attached Figure Description

[0051] Figure 1 This is an electron microscope image of the aerogel particles loaded with essential oil in Example 1 of the present invention;

[0052] Figure 2 This is an electron microscope image of the microcapsules obtained after encapsulation in Example 1 of the present invention;

[0053] Figure 3 Thermogravimetric curves of silica aerogel particles without any processing and microcapsules obtained after coating in Example 1 of the present invention;

[0054] Figure 4 Electron microscope image of the composite fiber prepared in Example 1 of the present invention;

[0055] Figure 5The aromatic substance sustained-release curves of the composite fiber prepared using aerogel particles that are not coated with the skin layer and only loaded with essential oil and the composite fiber prepared using skin-coated microcapsules in Application Example 1 of the present invention.

[0056] Figure 6 This is an electron microscope image of the composite fiber prepared in Example 2 of the present invention;

[0057] Figure 7 This is an electron microscope image of the composite fiber prepared in Example 3 of the present invention. Detailed Implementation

[0058] The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0059] Unless otherwise specified in the following examples, all raw materials were commercially available.

[0060] In the following description, the average diameter and porosity of the silica aerogel particles were obtained through actual testing after purchase; the amino silicone oil had an ammonia value of 0.53 mmol / g and was purchased from Guangzhou Xumei Chemical Technology Co., Ltd., grade WT1650CN; the epoxy modified silicone oil had an epoxy value of 0.25 mmol / g and was purchased from Qingdao Baisenmao New Materials Co., Ltd., grade BSM-204; sodium polyoxyethylene dodecyl ether sulfate (CAS No.: 9004-82-4), sodium oleate (CAS No.: 143-19-1), and sodium rosinate (CAS No.: 14351-66-7) were all purchased from Hangzhou Mike Chemical Instrument Co., Ltd.

[0061] Example 1

[0062] This example provides a method for preparing microcapsules and the prepared microcapsules. The method for preparing the microcapsules includes:

[0063] (1) Preparation of aerogel particles loaded with essential oils

[0064] Commercially available silica aerogel particles with an average diameter of 5 μm and a porosity of 72% were added to a sealed container. The container was then evacuated to a relative vacuum of -0.09 MPa. Commercially available osmanthus fragrance (the mass ratio of osmanthus fragrance to silica aerogel particles was 5:1) was then added dropwise to the silica aerogel particles under this vacuum environment. The container was left to stand for 15 minutes. After the essential oil had penetrated into the aerogel particles, the container was removed and water was added under normal pressure. The mixture was stirred for 5 minutes and then filtered to obtain aerogel particles loaded with essential oil.

[0065] (2) Preparation of microcapsules

[0066] Prepare aqueous solutions of polyoxyethylene dodecyl ether sodium sulfate, amino silicone oil, and epoxy modified silicone oil, each containing 1.0% by mass of solute.

[0067] Then proceed with the following steps:

[0068] a) The above-mentioned aerogel particles loaded with essential oil were added to a 1.0% sodium polyoxyethylene dodecyl ether sulfate aqueous solution, stirred and dispersed at room temperature for 5 min, filtered, washed with water and filtered again to obtain the first intermediate aerogel particles; wherein, the ratio of the mass of the aerogel particles loaded with essential oil to the volume of the sodium polyoxyethylene dodecyl ether sulfate aqueous solution was 0.01 (g / mL).

[0069] b) Then, the first intermediate aerogel particles were added to an amino silicone oil aqueous solution with a solute mass percentage of 1.0%, stirred at room temperature for 5 min, filtered, washed with water, and filtered again to obtain the second intermediate aerogel particles; wherein, the mass ratio of the first intermediate aerogel particles to the volume of the amino silicone oil aqueous solution was 0.01 in g / mL.

[0070] c) Then, the second intermediate aerogel particles were added to an epoxy-modified silicone oil aqueous solution with a solute mass percentage of 1.0%, and a film-forming reaction was carried out at 55°C for 15 min. After filtration, the microcapsules with skin coating were obtained. The mass ratio of the second intermediate aerogel particles to the volume of the epoxy-modified silicone oil aqueous solution was 0.01, in g / mL.

[0071] In this example, the electron microscope image of the aerogel particles loaded with essential oil obtained before coating is shown below. Figure 1 As shown in the figure, the electron microscope images of the microcapsules obtained after encapsulation are as follows. Figure 2 As shown in the figure, the comparison between the two figures shows that the surface of the coated microcapsules is denser and has smaller and fewer pores, which helps the aerogel microcapsules to obtain more durable and uniform sustained-release performance.

[0072] According to thermogravimetric analysis, such as Figure 3 As shown, Figure 3 In the figure, the curve before loading represents the thermogravimetric curve of silica aerogel particles without any operation, and the curve after loading fragrance represents the thermogravimetric curve of microcapsules processed in this example. The results show that the loading rate of osmanthus fragrance (mass percentage of osmanthus fragrance in the microcapsule mass) of the microcapsules processed in this example is 22.5%.

[0073] Example 2

[0074] This example provides a method for preparing microcapsules and the prepared microcapsules. The method for preparing the microcapsules includes:

[0075] (1) Preparation of aerogel particles loaded with essential oils

[0076] Commercially available silica aerogel particles with an average diameter of 0.65 μm and a porosity of 85% were added to a sealed container. The container was then evacuated to a relative vacuum of -0.085 MPa. Commercially available lavender essential oil (with a mass ratio of lavender essential oil to silica aerogel particles of 8.5:1) was then added dropwise to the silica aerogel particles under this vacuum environment. The container was left to stand for 15 minutes. After the essential oil had penetrated into the aerogel particles, the container was removed and water was added under normal pressure. The mixture was stirred for 5 minutes and then filtered to obtain aerogel particles loaded with essential oil.

[0077] (2) Preparation of microcapsules

[0078] Prepare aqueous solutions of sodium oleate (2.0% by mass), amino silicone oil (4.5% by mass), and epoxy-modified silicone oil (4.5% by mass) respectively.

[0079] Then proceed with the following steps:

[0080] a) Take the above-mentioned aerogel particles loaded with essential oil and add them to a sodium oleate aqueous solution with a solute mass percentage of 2.0%. Stir and disperse at room temperature for 5 minutes, filter, wash with water and filter again to obtain the first intermediate aerogel particles; wherein, the ratio of the mass of the aerogel particles loaded with essential oil to the volume of the sodium oleate aqueous solution is 0.04 in g / mL.

[0081] b) Then, the first intermediate aerogel particles were added to an amino silicone oil aqueous solution with a solute mass percentage of 4.5%, stirred at room temperature for 5 min, filtered, washed with water, and filtered again to obtain the second intermediate aerogel particles; wherein, the mass ratio of the first intermediate aerogel particles to the volume of the amino silicone oil aqueous solution was 0.04 in g / mL.

[0082] c) Then, the second intermediate aerogel particles were added to an epoxy-modified silicone oil aqueous solution with a solute mass percentage of 4.5%, and a film-forming reaction was carried out at 45°C for 45 min. After the reaction was carried out by suction filtration, microcapsules with skin coating were obtained. The ratio of the mass of the second intermediate aerogel particles to the volume of the epoxy-modified silicone oil aqueous solution was 0.04, in g / mL.

[0083] Implementation effect analysis: In this case, microcapsules with uniform surface coating were obtained; thermogravimetric analysis showed that the loading rate of lavender essential oil (the mass percentage of lavender essential oil in the microcapsules) was 45.5%.

[0084] Example 3

[0085] This example provides a method for preparing microcapsules and the prepared microcapsules. The method for preparing the microcapsules includes:

[0086] (1) Preparation of aerogel particles loaded with essential oils

[0087] Commercially available silica aerogel particles with an average diameter of 10 μm and a porosity of 92% were added to a sealed container. The container was then evacuated to a relative vacuum of -0.07 MPa. Commercially available rose essential oil (with a mass ratio of rose essential oil to silica aerogel particles of 9:1) was then added dropwise to the silica aerogel particles under this vacuum environment. The container was left to stand for 15 minutes. After the essential oil had penetrated into the aerogel particles, the container was removed and water was added under normal pressure. The mixture was stirred for 5 minutes and then filtered to obtain aerogel particles loaded with essential oil.

[0088] (2) Preparation of microcapsules

[0089] Prepare aqueous solutions of sodium rosinate (0.3% by mass), amino silicone oil (0.3% by mass), and epoxy-modified silicone oil (0.3% by mass) respectively.

[0090] Then proceed with the following steps:

[0091] a) Take the above-mentioned aerogel particles loaded with essential oil and add them to a sodium rosinate aqueous solution with a solute mass percentage of 0.3%. Stir and disperse at room temperature for 5 minutes, filter, wash with water and filter again to obtain the first intermediate aerogel particles; wherein, the ratio of the mass of the aerogel particles loaded with essential oil to the volume of the sodium rosinate aqueous solution is 0.0056 in g / mL.

[0092] b) Then, the first intermediate aerogel particles were added to an amino silicone oil aqueous solution with a solute mass percentage of 0.3%, stirred at room temperature for 5 min, filtered, washed with water, and filtered again to obtain the second intermediate aerogel particles; wherein, the mass ratio of the first intermediate aerogel particles to the volume of the amino silicone oil aqueous solution was 0.0056 in g / mL.

[0093] c) Then, the second intermediate aerogel particles were added to an epoxy-modified silicone oil aqueous solution with a solute mass percentage of 0.3%, and a film-forming reaction was carried out at 58°C for 8 min. After filtration, the microcapsules with skin coating were obtained. The mass ratio of the second intermediate aerogel particles to the volume of the epoxy-modified silicone oil aqueous solution was 0.0056, in g / mL.

[0094] Implementation effect analysis: In this case, microcapsules with uniform surface coating were obtained; thermogravimetric analysis showed that the loading rate of rose essential oil (the percentage of rose essential oil in the mass of the microcapsules) was 65.3%.

[0095] Example 4

[0096] This example provides a method for preparing microcapsules and the prepared microcapsules. The method for preparing the microcapsules includes:

[0097] (1) Preparation of aerogel particles loaded with essential oils

[0098] Commercially available silica aerogel particles with an average diameter of 2 μm and a porosity of 68% were added to a sealed container. The container was then evacuated to a relative vacuum of -0.05 MPa. Commercially available ambroxol flavoring (the mass ratio of ambroxol flavoring to silica aerogel particles was 0.8:1) was then added dropwise to the silica aerogel particles under this vacuum environment. After standing for 15 minutes, once the essential oil had penetrated into the aerogel particles, the container was removed. Water was added under normal pressure, and the mixture was stirred for 5 minutes. The mixture was then filtered to obtain aerogel particles loaded with essential oil.

[0099] (2) Preparation of microcapsules

[0100] Prepare aqueous solutions of sodium rosinate (4.5% by mass), amino silicone oil (2.5% by mass), and epoxy-modified silicone oil (2.5% by mass) respectively.

[0101] Then proceed with the following steps:

[0102] a) Take the above-mentioned aerogel particles loaded with essential oil and add them to a sodium rosinate aqueous solution with a solute mass percentage of 4.5%. Stir and disperse at room temperature for 5 minutes, filter, wash with water and filter again to obtain the first intermediate aerogel particles; wherein, the ratio of the mass of the aerogel particles loaded with essential oil to the volume of the sodium rosinate aqueous solution is 0.0167 in g / mL.

[0103] b) Then, the first intermediate aerogel particles were added to an amino silicone oil aqueous solution with a solute mass percentage of 2.5%, stirred at room temperature for 5 min, filtered, washed with water and filtered again to obtain the second intermediate aerogel particles; wherein, the mass ratio of the first intermediate aerogel particles to the volume of the amino silicone oil aqueous solution was 0.0167 in g / mL.

[0104] c) Then, the second intermediate aerogel particles were added to an epoxy-modified silicone oil aqueous solution with a solute mass percentage of 2.5%, and a film-forming reaction was carried out at 50°C for 20 min. After filtration, the microcapsules with skin coating were obtained. The mass ratio of the second intermediate aerogel particles to the volume of the epoxy-modified silicone oil aqueous solution was 0.0167, in g / mL.

[0105] Implementation effect analysis: In this example, microcapsules with uniform surface coating were obtained; thermogravimetric analysis showed that the loading rate of ambroxol flavor (the mass percentage of ambroxol flavor in the microcapsules) was 18.1%.

[0106] Example 5

[0107] This example provides a method for preparing microcapsules and the prepared microcapsules. The method for preparing the microcapsules includes:

[0108] (1) Preparation of aerogel particles loaded with essential oils

[0109] Commercially available silica aerogel particles with an average diameter of 1.2 μm and a porosity of 70% were added to a sealed container. The container was then evacuated to a relative vacuum of -0.042 MPa. Commercially available sweet orange essential oil (with a mass ratio of sweet orange essential oil to silica aerogel particles of 0.6:1) was then added dropwise to the silica aerogel particles under this vacuum environment. The container was left to stand for 15 minutes. After the essential oil had penetrated into the aerogel particles, the container was removed, water was added under normal pressure, and the mixture was stirred for 5 minutes. The mixture was then filtered to obtain aerogel particles loaded with essential oil.

[0110] (2) Preparation of microcapsules

[0111] Prepare aqueous solutions of polyoxyethylene dodecyl ether sodium sulfate, amino silicone oil, and epoxy modified silicone oil, each containing 0.15% by mass of solute.

[0112] Then proceed with the following steps:

[0113] a) Take the above-mentioned aerogel particles loaded with essential oil and add them to a sodium polyoxyethylene dodecyl ether sulfate aqueous solution with a solute mass percentage of 0.15%. Stir and disperse at room temperature for 5 min, filter, wash with water and filter again to obtain the first intermediate aerogel particles; wherein, the ratio of the mass of the aerogel particles loaded with essential oil to the volume of the sodium polyoxyethylene dodecyl ether sulfate aqueous solution is 0.04 (g / mL).

[0114] b) Then, the first intermediate aerogel particles were added to an amino silicone oil aqueous solution with a solute mass percentage of 0.15%, stirred at room temperature for 5 min, filtered, washed with water, and filtered again to obtain the second intermediate aerogel particles; wherein, the mass ratio of the first intermediate aerogel particles to the volume of the amino silicone oil aqueous solution was 0.04 in g / mL.

[0115] c) Then, the second intermediate aerogel particles were added to an epoxy-modified silicone oil aqueous solution with a solute mass percentage of 0.15%, and a film-forming reaction was carried out at 45°C for 60 min. After filtration, the microcapsules with skin coating were obtained. The mass ratio of the second intermediate aerogel particles to the volume of the epoxy-modified silicone oil aqueous solution was 0.04, in g / mL.

[0116] Implementation effect analysis: In this case, microcapsules with uniform surface coating were obtained; thermogravimetric analysis showed that the loading rate of sweet orange essential oil (the mass percentage of sweet orange essential oil in the microcapsules) was 16.5%.

[0117] Comparative Example 1

[0118] The process is basically the same as in Example 5, except that "sodium polyoxyethylene dodecyl ether sulfate aqueous solution with a solute mass percentage of 0.15%" is replaced with "dodecyl trimethylammonium salt aqueous solution with a solute mass percentage of 0.15%".

[0119] The prepared microcapsules had an indistinct outer layer and were relatively thin.

[0120] Comparative Example 2

[0121] The method is basically the same as in Example 5, except that "aqueous amino silicone oil with a solute mass percentage of 0.15%" is replaced with "aqueous dimethyl silicone oil with a solute mass percentage of 0.15%".

[0122] The prepared microcapsules had an indistinct outer layer and were relatively thin.

[0123] Comparative Example 3

[0124] The process is basically the same as in Example 5, except that the temperature of the film-forming reaction is changed to 27°C.

[0125] The prepared microcapsules had an indistinct outer layer and were relatively thin.

[0126] Comparative Example 4

[0127] The procedure was essentially the same as in Example 5, except that commercially available sweet orange essential oil was added dropwise to the silica aerogel particles under normal pressure and then mixed. Thermogravimetric analysis showed that the loading rate of sweet orange essential oil (the percentage of sweet orange essential oil by mass of the microcapsules) was 2.3%. This indicates that under normal pressure, the essential oil has difficulty penetrating the interior of the aerogel particles with their surface micropores.

[0128] Application Example 1

[0129] This example provides a composite fiber comprising a fiber matrix and aromatic sustained-release capsules dispersed in the fiber matrix. The aromatic sustained-release capsules are microcapsules prepared in Example 1, and the fiber matrix is ​​modal fiber.

[0130] The preparation method of this composite fiber includes:

[0131] Aromatic sustained-release capsules are dispersed in modal spinning solution, spun according to known modal fiber spinning methods, and treated with the post-processing conditions specified in this document to obtain composite fibers.

[0132] Of which, by mass percentage, the amount of aromatic sustained-release capsules added accounts for 8% of the solute mass of the modal spinning solution;

[0133] The spinning process is as follows: pulp raw material → alkalization → aging → xanthation → dissolution → filtration → addition of microcapsules → degassing → maturation → wet spinning → drawing → post-treatment → drying → winding and packaging.

[0134] Alkalization: Dissolve the pulp raw material in a NaOH aqueous solution with a mass fraction of 18% and a temperature of 50℃ at a pulp / alkali solution mass-volume ratio of 1:20;

[0135] Old method: Keep the pulp alkaline solution at 30℃ for 20 hours to allow the macromolecules to oxidize and depolymerize;

[0136] Yellowing: CS2 is introduced at a mass ratio of 30% to pulp raw material to carry out the yellowing reaction. The initial reaction temperature is 20℃, the final temperature is 28℃, and the reaction time is 1.5h.

[0137] Dissolving, filtering, and adding microcapsules: The xanthated product is dissolved in a 7.0% NaOH aqueous solution, the insoluble matter is removed by filtration, and then microcapsules are added at a certain mass fraction.

[0138] Maturation: After degassing, place at 15°C for 24 hours to allow some macromolecules to saponify and hydrolyze;

[0139] Wet spinning: spinning hole diameter 80μm, spinning speed 32m / s, coagulation bath composition 72g / L sulfuric acid, 78g / L zinc sulfate, 170g / L sodium sulfate, coagulation bath temperature 50℃, immersion time of filament in coagulation bath is 1 second;

[0140] Stretch: The elongation rate is 55%;

[0141] The post-treatment includes desulfurization and water washing. A mixture of sodium sulfite and sodium hydroxide is used as the desulfurizing agent, and a desulfurization bath is prepared with penetrant JFC and water. The concentration of sodium sulfite is 12 g / L, the concentration of sodium hydroxide is 2 g / L, the concentration of penetrant JFC is 1.5 g / L, the desulfurization bath temperature is 58℃, and the water washing bath temperature is 45℃.

[0142] This example yielded a composite fiber with a uniform structure, a strength of 2.3 cN / dtex, and containing aromatic sustained-release capsules (electron microscope image shown). Figure 4(As shown); the composite fiber has a strong osmanthus fragrance, and even after being left at room temperature for 6 months, the fiber still retains a distinct osmanthus fragrance. After being left at room temperature for 11 months, the residual rate of fragrance substances in the fiber is still as high as 50.3%, while the residual rate of fragrance substances in the composite fiber prepared by adding aerogel particles that are not coated with the skin layer and only loaded with essential oils is only 10.1% (the sustained-release curve of the aromatic fiber measured by the above thermogravimetric analysis method is shown in Figure 1). Figure 5 As shown in the figure, the composite fiber prepared by this method releases its fragrance substances much more slowly and for a longer period of time.

[0143] Application Example 2

[0144] The application is basically the same as in Example 1, except that the aromatic sustained-release capsules are microcapsules prepared in Example 2, and the amount of aromatic sustained-release capsules added accounts for 3.5% of the solute mass of the modal spinning solution by mass percentage.

[0145] In the post-treatment process conditions: the desulfurization bath temperature is 50℃, and the water washing bath temperature is 50℃.

[0146] This example yielded a composite fiber with a uniform structure, a strength of 2.9 cN / dtex, and containing aromatic sustained-release capsules (electron microscope image shown). Figure 6 (As shown); the composite fiber has a strong lavender essential oil fragrance, and even after being placed at room temperature for 6 months, the fiber still has a faint lavender essential oil fragrance. After being placed at room temperature for 11 months, the content of aromatic substances in the fiber was tested by thermogravimetric analysis. The residual rate of aromatic substances in the fiber obtained in this example was still as high as 32.5%, while the residual rate of aromatic substances in the composite fiber prepared by adding aerogel particles that are not coated with the skin layer and only loaded with essential oil was only 10.7%. It can be seen that the composite fiber prepared by this method has a significantly slower and longer-lasting release of aromatic substances.

[0147] Application Example 3

[0148] The application is basically the same as in Example 1, except that the aromatic sustained-release capsules are microcapsules prepared in Example 3, and the amount of aromatic sustained-release capsules added accounts for 11.5% of the solute mass of the modal spinning solution by mass percentage.

[0149] In the post-treatment process conditions: the desulfurization bath temperature is 45℃, and the water washing bath temperature is 45℃.

[0150] This example yielded a composite fiber with a uniform structure, a strength of 1.8 cN / dtex, and containing aromatic sustained-release capsules (electron microscope image shown). Figure 7(As shown); the composite fiber has a strong rose essential oil fragrance, and the fiber still has a distinct rose essential oil fragrance after being placed at room temperature for 6 months. After being placed at room temperature for 11 months, the content of aromatic substances in the fiber was tested by thermogravimetric analysis. The residual rate of aromatic substances in the fiber obtained in this example was still as high as 53.3%, while the residual rate of aromatic substances in the composite fiber prepared by adding aerogel particles that are not coated with the skin layer and only loaded with essential oil was only 9.6%. It can be seen that the composite fiber prepared by this method has a significantly slower and longer-lasting release of aromatic substances.

[0151] Application Example 4

[0152] The application is basically the same as in Example 1, except that the aromatic sustained-release capsules are microcapsules prepared in Example 4, and the amount of aromatic sustained-release capsules added accounts for 7.0% of the solute mass of the modal spinning solution by mass percentage.

[0153] In the post-treatment process conditions: the desulfurization bath temperature is 45℃, and the water washing bath temperature is 55℃.

[0154] This example yielded a composite fiber with a uniform structure, a strength of 2.5 cN / dtex, and containing aromatic sustained-release capsules. The composite fiber has a strong ambroxol aroma, and even after being stored at room temperature for 6 months, the fiber still retains a certain amount of ambroxol aroma. After being stored at room temperature for 11 months, the content of aromatic substances in the fiber was tested using thermogravimetric analysis. The residual rate of aromatic substances in the fiber obtained in this example was still as high as 45.2%, while the residual rate of aromatic substances in the composite fiber prepared by adding aerogel particles that are not coated with a skin layer and are only loaded with essential oils was only 8.8%. It can be seen that the composite fiber prepared by this method has a significantly slower and longer-lasting release of aromatic substances.

[0155] Application Example 5

[0156] The application is basically the same as in Example 1, except that the aromatic sustained-release capsules are microcapsules prepared in Example 5, and the amount of aromatic sustained-release capsules added accounts for 3.5% of the solute mass of the modal spinning solution by mass percentage.

[0157] In the post-treatment process conditions: the desulfurization bath temperature is 58℃, and the water washing bath temperature is 58℃.

[0158] This example yielded a composite fiber with a uniform structure, a strength of 3.1 cN / dtex, and containing aromatic sustained-release capsules. The composite fiber has a certain concentration of sweet orange fragrance, and even after being placed at room temperature for 6 months, the fiber still retains a faint sweet orange fragrance. After being placed at room temperature for 11 months, the content of aromatic substances in the fiber was tested using thermogravimetric analysis. The residual rate of aromatic substances in the fiber obtained in this example was still as high as 30.1%, while the residual rate of aromatic substances in the composite fiber prepared by adding aerogel particles that are not coated with a cortex and only loaded with essential oils was only 7.7%. It can be seen that the composite fiber prepared by this method has a significantly slower and longer-lasting release of aromatic substances.

[0159] Application Comparative Example 1

[0160] The application is basically the same as in Example 5, except that the aromatic sustained-release capsules are microcapsules prepared in Comparative Example 1.

[0161] The fragrance of the resulting composite fiber was almost non-existent after 5 weeks at room temperature, indicating that the fragrance substances in the microcapsules were released too quickly. Analysis suggests that this is because dodecyltrimethylammonium salt, a cationic surfactant, carries a positive charge and repels the positively charged amino silicone oil. This hinders the enrichment and coating of these substances on the surface of the aerogel particles, making it difficult for them to react in sufficient quantities with the epoxy-modified silicone oil to form a skin of ideal thickness.

[0162] Application Comparative Example 2

[0163] The application is basically the same as in Example 5, except that the aromatic sustained-release capsules are microcapsules prepared in Comparative Example 2.

[0164] The fragrance of the resulting composite fiber was very weak after being left at room temperature for 5 weeks, indicating that the fragrance substances in the microcapsules were released too quickly. Analysis suggests that this is because dimethyl silicone oil is electrically neutral and lacks electrostatic attraction with positively charged amino silicone oil, which is not conducive to the enrichment and coating of these substances on the surface of aerogel particles. Consequently, it is difficult for these substances to react in sufficient quantities with epoxy-modified silicone oil to form a skin layer of ideal thickness.

[0165] Application Comparative Example 3

[0166] The application is basically the same as in Example 5, except that the aromatic sustained-release capsules are microcapsules prepared in Comparative Example 3.

[0167] The fragrance of the resulting composite fiber was almost nonexistent after being left at room temperature for 5 weeks, indicating that the fragrance substances in the microcapsules were released too quickly. Analysis suggests that the reaction temperature was too low, making it difficult to achieve a complete reaction within the limited time, resulting in an unsatisfactory skin layer thickness and thus causing the excessively rapid release.

[0168] Application Comparative Example 4

[0169] The application is basically the same as in Example 5, except that the aromatic sustained-release capsules are microcapsules prepared in Comparative Example 4. The resulting composite fibers have virtually no fragrance, which is believed to be due to the small amount of fragrance substances loaded onto the microcapsules.

[0170] Application Comparative Example 5

[0171] The application is basically the same as in Example 5, except that the desulfurization bath temperature is adjusted to 75°C, which is commonly used in the preparation of modal fibers, and the water bath temperature is 75°C.

[0172] The resulting composite fiber has a weak fragrance, which becomes very faint after being left at room temperature for 5 weeks. The fragrance substances in the microcapsules are lost due to excessive volatilization during the fiber preparation process.

[0173] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0174] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A microcapsule, characterized in that, The microcapsule comprises aerogel particles loaded with essential oil and a skin layer covering the aerogel particles loaded with essential oil, the skin layer being an organosilicon membrane. The oil-loaded aerogel particles are prepared by loading aromatic essential oils onto silica aerogel particles with a porous structure under negative pressure. The silica aerogel particles have a particle size of 0.5-10 μm and a porosity of 65%-95%. The method for preparing the organosilicon film includes: The aerogel particles loaded with essential oil are mixed with a surfactant to obtain a first intermediate aerogel particle. The surface of the first intermediate aerogel particle is adsorbed with the surfactant. After the surfactant is ionized in water, some of the groups that play a surface-active role are negatively charged. The first intermediate aerogel particles and amino silicone oil are mixed to obtain a second intermediate aerogel particles, the surface of which is coated with the amino silicone oil. The second intermediate aerogel particles and epoxy-modified silicone oil are mixed and reacted at 40-60°C.

2. A microcapsule, characterized in that, The microcapsule comprises aerogel particles loaded with essential oil and a skin layer covering the aerogel particles loaded with essential oil, the skin layer being an organosilicon membrane. The method for preparing the microcapsules includes: (1) Preparation of aerogel particles loaded with essential oils Silica aerogel particles with a porous structure are added to a container, and the container is evacuated to a negative pressure condition. Then, aromatic essential oils are added dropwise to the container and allowed to stand until the aromatic essential oils penetrate into the porous structure of the silica aerogel particles. The container is then removed, mixed with water under normal pressure, stirred, and filtered to obtain aerogel particles loaded with essential oils. The particle size of the silica aerogel particles is 0.5-10 μm, and the porosity is 65%-95%. (2) Preparation of microcapsules The aerogel particles loaded with essential oils were added to an aqueous solution of surfactant, stirred and dispersed, filtered, washed with water, and filtered again to obtain the first intermediate aerogel particles; the surfactant in the aqueous solution had negatively charged groups that were active after ionization in water. The first intermediate aerogel particles were added to an amino silicone oil aqueous solution, stirred and dispersed, filtered, washed with water, and filtered again to obtain the second intermediate aerogel particles. The second intermediate aerogel particles were added to an epoxy-modified silicone oil aqueous solution and reacted at 40-60°C. After the reaction was completed, the mixture was filtered to obtain the microcapsules coated with the skin layer.

3. The microcapsule according to claim 1 or 2, characterized in that, The silica aerogel particles have a particle size of 1-5 μm.

4. The microcapsule according to claim 1 or 2, characterized in that, The porosity of the silica aerogel particles is 85%-95%.

5. The microcapsule according to claim 1 or 2, characterized in that, The negative pressure condition satisfies a relative vacuum degree of -0.1 to -0.04 MPa, and the mass ratio of the aromatic essential oil to the silica aerogel particles is 0.5-10:

1.

6. The microcapsule according to claim 2, characterized in that, The mass percentage concentrations of the surfactant aqueous solution, the amino silicone oil aqueous solution, and the epoxy modified silicone oil aqueous solution are 0.1%-5.0%, respectively.

7. The microcapsule according to claim 6, characterized in that, The ratios of the mass of the oil-loaded aerogel particles to the volume of the surfactant aqueous solution, the ratio of the mass of the first intermediate aerogel particles to the volume of the amino silicone oil aqueous solution, and the ratio of the mass of the second intermediate aerogel particles to the volume of the epoxy-modified silicone oil aqueous solution, in g / mL, are 0.005-0.05, respectively.

8. The microcapsule according to claim 1 or 2, characterized in that, The surfactant is selected from one or more of sodium polyoxyethylene dodecyl ether sulfate, sodium oleate, and sodium rosinate; The structural formula of amino silicone oil is: In formula (Ⅰ): R0 is a hydrocarbon group or a hydrocarbon oxygen group, and R1 is a C group. 1-6 Alkylene, n and m are independently 1-200; The structural formula of epoxy-modified silicone oil is: In formula (II): R2 is a hydrocarbon group or hydrocarbon group, R3 is a C1-6 alkylene group, and a and b are independently 1-200.

9. A composite fiber, characterized in that, The method for preparing the composite fiber includes: The aromatic sustained-release capsules were dispersed in modal spinning solution, and the composite fiber was obtained by spinning and post-treatment. The aromatic sustained-release capsule comprises the microcapsules according to any one of claims 1-8; During the post-treatment process, the desulfurization bath temperature is 45-60℃ and the water washing bath temperature is 45-60℃.

10. The composite fiber according to claim 9, characterized in that, A desulfurizing bath is prepared by using a mixture of sodium sulfite and sodium hydroxide as a desulfurizing agent, and by combining it with penetrant JFC and water; and / or, by mass percentage, the amount of the aromatic sustained-release capsules added accounts for 3%-12% of the solute mass of the modal spinning solution.

Images