Lasting, stable and slow-release fragrance-releasing antibacterial microcapsule as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of functional porous carbon microcapsule preparation, and relates to a lasting, stable and slow-release fragrance-releasing antibacterial microcapsule as well as a preparation method and application thereof. The air purifying agent comprises the following components in percentage by weight: 30-60% of porous carbon microspheres, 10-30% of micromolecular essential oil, 20-50% of an organic matrix and 10-30% of an inorganic salt solution. According to the aroma-releasing antibacterial microcapsule, the bio-based porous carbon microspheres are adopted to load natural micromolecular essential oil, and organic-inorganic mineralization coating on the surfaces of the microspheres is realized through an organic matrix and an inorganic salt solution, so that the hardness, heat resistance and other properties of microsphere particles are improved, stable slow release of aromatic active substances is realized, and the time can last for more than 2 years.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of functional porous carbon microcapsules, and relates to a fragrance-releasing and antibacterial microcapsule with persistent and stable slow release, a preparation method thereof and an application thereof. Background Art

[0002] Traditional wood-based panels have long been criticized for problems such as formaldehyde release from adhesives, TVOC (total volatile organic compounds) pollution and odor problems. Although low-formaldehyde production has been achieved through technologies such as formaldehyde-free adhesives and formaldehyde scavengers, the pursuit of natural and healthy functions by consumers still drives the industry to transform towards high added value. Currently, with the upgrading of the demand for indoor environmental health and safety, the technical demand for antibacterial and fragrance-releasing functional wood-based panels is becoming increasingly prominent.

[0003] Natural plant extracts, with their natural antibacterial properties (such as the antibacterial rate of Artemisia argyi essential oil against Escherichia coli and Staphylococcus aureus > 99%) and fragrance-releasing characteristics (the fragrance retention time reaches several months), have become the core functional carriers. However, the characteristics of easy volatility and strong thermal sensitivity of plant extracts make the traditional direct addition method have problems such as poor stability and easy loss of active ingredients, which limits its application scope. Microcapsule technology isolates active ingredients through a core-shell structure to achieve a slow release function, and has currently been widely used in the coating of traditional Chinese medicine extracts (such as Artemisia argyi, Isatis indigotica, etc.), and has been extended to fields such as waterborne coatings and sprays.

[0004] In the manufacture of wood-based panels, adding fragrance-releasing and antibacterial microcapsules to adhesives can endow the panels with antibacterial (inhibiting the growth of bacteria inside and outside the panels) and fragrance-releasing (purifying odors) functions; for example, Guangdong Aigo Smart Home Co., Ltd. successfully developed the "Aixiang Board" that meets the LY / T 3230-2020 standard through the compound technology of adding Chinese herbal medicine powder and essential oil microcapsules, achieving the standard release of TVOC and high-efficiency antibacterial; the Mogan Mountain Plant Source · Fragrance-Releasing Board developed by Zhejiang Shenghua Yunfeng Mogan Mountain Co., Ltd. uses a fragrance-locking technology to retain the natural fragrance of lavender, and the antibacterial rate is still > 99.99% after 5000 washes, and the TVOC release concentration meets the Class I standard, and has health care functions such as helping sleep and relieving pain.

[0005] Due to the high temperature, high pressure and acid-base environment in the wood-based panel processing process, it is easy to cause the collapse of the traditional microcapsule wall material, resulting in the instantaneous release or dissociation of active ingredients, and it is difficult to achieve a lasting effect. For example, although Chinese Patent CN112176451 A adopts a double-layer wall capsule microcapsule structure (inner layer β-cyclodextrin, outer layer porous starch), which effectively reduces the loss of encapsulated substances, its capsule wall still has problems of insufficient pressure resistance and heat resistance.

[0006] The existing technology faces three major challenges: First, the mechanical strength of the microcapsule shell material is low, making it difficult to resist processing stress; second, the heat resistance stability is poor, and it is prone to failure at high temperatures; third, the slow-release efficiency is insufficient and cannot meet the long-term functional requirements. It is difficult for a single organic or inorganic shell material to balance the performance, and its materials and processes need to be further improved. Summary of the Invention

[0007] One object of the present invention is to provide a fragrance-releasing and antibacterial porous carbon microsphere with persistent and stable slow release to solve the problem that the existing microcapsules are not pressure-resistant and not high-temperature resistant. It uses bio-based porous carbon microspheres to load small molecule essential oils, and realizes organic-inorganic mineralization coating on the surface through an organic matrix and an inorganic salt solution to improve the hardness, heat resistance, corrosion resistance and other properties of the microcapsules, and at the same time has persistent and stable slow release of fragrance-releasing and antibacterial active substances, and can be applied to the artificial board adhesive system. The second object of the present invention is to provide a preparation method of a fragrance-releasing and antibacterial microcapsule with persistent and stable slow release.

[0008] The third object of the present invention is to provide an application of a fragrance-releasing and antibacterial microcapsule with persistent and stable slow release in the preparation process of artificial board adhesives or paint films.

[0009] To achieve the first object of the invention, the present invention can be realized by the following technical solutions: A fragrance-releasing and antibacterial microcapsule with persistent and stable slow release, calculated by mass percentage, includes the following components in the following contents: Porous carbon microspheres 30-60%, small molecule essential oils 10-30%, organic matrix 20-50% and inorganic salt solution 10-30%.

[0010] The beneficial effects of adopting the above technical solutions are: (1) The present invention uses bio-based porous carbon microspheres to load natural small molecule essential oils, and realizes organic-inorganic mineralization coating on the surface of the microspheres through an organic matrix and an inorganic salt solution to improve the hardness, heat resistance and other properties of the microsphere particles, and realizes stable slow release of aromatic active substances, and the time can last for more than 2 years.

[0011] (2) The present invention uses natural plant essential oil as the fragrance-releasing and antibacterial active substance, self-assembles plant-derived or animal-derived fibers into porous microspheres, and obtains porous carbon microsphere adsorption carriers through hydrothermal carbonization-activation. Due to the high hardness, porosity, and high specific surface area of ​​the porous carbon microspheres, they can load more essential oil active substances and provide mechanical strength during the hot pressing process. At the same time, the thermal conductivity of the carbon is low, and the biologically active components loaded inside it will play a role in high temperature protection under short-term high temperature conditions during the material manufacturing process. Then, polysaccharides or proteins are used. The organic matrix is ​​coated, and finally an inorganic salt solution is introduced into the matrix to form an organic-inorganic mineral layer on the surface of the microspheres. On the one hand, the mineral layer containing inorganic ions can play a synergistic antiviral effect. At the same time, the mineral layer with hardness, heat resistance, acid and alkali resistance further improves the physical and mechanical properties and chemical stability of the porous carbon microspheres, thereby achieving dual protection of loaded active substances. The mineralized modified porous carbon microcapsules of the present invention can be widely used in the adhesive system and paint film system of artificial boards, achieving long-lasting and stable slow-release antibacterial and fragrance-releasing effects, with a validity period of several years.

[0012] In a specific embodiment of the present invention, the porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing an organic precursor; the organic precursor includes a plant source rich in cellulose or an animal source rich in organic matter; the plant source includes any one of wood fiber, straw and plant residue; the animal source includes any one of chitin, animal bones and cuticle. In a specific embodiment of the present invention, the porous carbon microspheres are prepared by the following method: (11) crushing and grinding the plant source or animal source, and then acid washing and / or alkali washing to obtain pretreated product I; (12) adding a binder to the pretreated product I, mixing them evenly, and then spheroidizing them to obtain spherical particles with a diameter in the micrometer scale, thereby obtaining a pretreated product II; (13) The pretreated product II is then carbonized in nitrogen or argon at 500-1000°C for 1-10 hours to obtain a spherical material with a spherical diameter of 30-50 μm, a mesopore diameter of 2-50 nm, and a specific surface area of ​​300-1500 m 2 / g porous carbon microspheres; (14) The porous carbon microspheres are then activated and dried to obtain the final porous carbon microspheres.

[0013] In a specific embodiment of the present invention, the pickling agent is hydrochloric acid or sulfuric acid, the pickling agent concentration is 1M-5M, and the reaction time is 1-3 hours; The alkaline washing agent is sodium hydroxide or potassium hydroxide; the reaction pH value is 11-12, the reaction temperature is 60-90° C., and the reaction time is 2-4 hours.

[0014] In a specific embodiment of the present invention, the addition amount of the binder is 5-30%; the binder includes any one or a mixture of several of polypropylene, polyethylene, polylactic acid, starch, gum arabic and gelatin. In a specific embodiment of the present invention, the spheroidization treatment includes wet spheroidization, spray drying spheroidization, extrusion molding, rotary spheroidization, oscillating spheroidization or spray cooling spheroidization.

[0015] In a specific embodiment of the present invention, the activation treatment includes physical activation and / or chemical activation; the physical activation includes high-temperature steam or nitrogen activation; the reagents used in the chemical activation include sodium hydroxide, potassium hydroxide or hydrogen peroxide.

[0016] In a specific embodiment of the present invention, the small molecule essential oil is an oil compound extracted from plants, and its molecular weight < 300; the plant is any one of mint, tea tree, rosemary, thyme and eucalyptus.

[0017] In a specific embodiment of the present invention, the organic matrix is a polysaccharide or a protein, including any one of gelatin, sodium alginate, hyaluronic acid and carboxymethyl cellulose.

[0018] In a specific embodiment of the present invention, the inorganic salt solution is a cation solution, including any one of sodium chloride, copper sulfate, potassium nitrate, sodium carbonate or calcium chloride.

[0019] In order to achieve the second invention object, the present invention can be realized by the following technical solutions: providing a preparation method of a fragrance-releasing and antibacterial microcapsule with persistent, stable and slow release, including: Load the small molecule essential oil in the formula amount on the porous carbon microspheres respectively, and then coat the organic matrix and the inorganic salt solution on the porous carbon microspheres loaded with the small molecule essential oil in sequence to obtain the fragrance-releasing and antibacterial microcapsule with persistent, stable and slow release.

[0020] The beneficial effects of adopting the above technical solution are as follows: The present invention uses bio-based porous carbon microspheres loaded with natural small molecule essential oils, and realizes the organic-inorganic mineralization coating on the surface of the microspheres through an organic matrix and an inorganic salt solution to improve the hardness, heat resistance and other properties of the microsphere particles, and realizes the stable slow release of aromatic active substances for a time of more than 2 years; in the present invention, the essential oil molecules interact with the surface of the porous carbon microspheres through van der Waals forces and hydrogen bonds, and the essential oil molecules can be adsorbed on the surface or pores of the carbon microspheres to ensure the loading and stability of the essential oils; the organic matrix layer is coated on the surface of the porous carbon microspheres to enhance the encapsulation and release control of the essential oils and avoid the rapid volatilization of the essential oils; the organic matrix layer provides an attachment surface for the inorganic mineralization layer, and the inorganic mineralization layer is stably coated on the matrix layer by chemical reaction or physical deposition to improve the heat resistance stability and slow release performance of the overall composite material; this capsule can be stably and durably miscible with the adhesives and surface coatings used in wood-based panels to achieve a long-lasting and stable antibacterial and fragrance-releasing effect without producing toxic side effects.

[0021] In a specific embodiment of the present invention, a method for preparing a fragrance-releasing and antibacterial microcapsule with long-lasting and stable slow release is provided, including: (1) Prepare porous carbon microspheres; (2) Mix the porous carbon microspheres, small molecule essential oils, deionized water and ethanol, and disperse them evenly at 5000 - 8000 r / min for 2 - 10 min to obtain porous carbon microspheres loaded with small molecule essential oils; the mass ratio of the porous carbon microspheres, small molecule essential oils, deionized water and ethanol is 1:0.1 - 1:1 - 3:10 - 20.

[0022] (3) Add an organic matrix solution with a mass fraction of 20 - 50% to the product obtained in step (2), then add a coupling agent with a mass fraction of 0.5 - 1.5% and a dispersant with a mass fraction of 0.5 - 1.5% and mix them, stir until the organic matrix is completely dissolved, and then homogenize and disperse at 5000 - 8000 r / min for 5 - 15 minutes; (4) Add an inorganic salt solution with a mass fraction of 10 - 30% to the product obtained in step (3), then stir and disperse at 800 - 1000 r / min for 2 - 4 h, and after filtration and drying, obtain a fragrance-releasing and antibacterial microcapsule with a long-lasting and stable slow release and an organic-inorganic mineralization layer on the surface shell.

[0023] The beneficial effects of adopting the above technical solutions are as follows: In the present invention, natural plant essential oils are used as fragrance-releasing and antibacterial active substances. Porous microspheres are self-assembled from plant-derived or animal-derived fibers and then hydrothermally carbonized and activated to obtain a porous carbon microsphere adsorption carrier. Due to the high hardness, multi-porosity, and high specific surface area characteristics of the porous carbon microspheres, a larger amount of essential oil active substances can be loaded, and mechanical strength can be provided during the hot pressing process. At the same time, the thermal conductivity of carbon is relatively low, which can play a role in protecting the bioactive components loaded inside from high temperatures under short-term high-temperature conditions during the material production process. Then, a polysaccharide-based or protein-based organic matrix is used for coating, and finally, an inorganic salt solution is introduced onto this matrix to form an organic-inorganic mineralized layer on the surface of the microspheres. On the one hand, the mineralized layer containing inorganic ions can play a synergistic antiviral effect, and the mineralized layer with hardness, heat resistance, and acid and alkali resistance further improves the physical and mechanical properties and chemical stability of the porous carbon microspheres, realizing double protection of the loaded active substances. Due to the addition of coupling agents, dispersants, surfactants, etc. during the preparation process, good interfacial compatibility with water is maintained. This mineralized modified porous carbon microcapsule can be widely applied to the adhesive system and paint film system of wood-based panels, achieving a long-lasting and stable slow-release antibacterial and fragrance-releasing effect, with an effective period of up to several years.

[0024] In a specific embodiment of the present invention, the coupling agent is a mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane, with a mass ratio of 2:1; the dispersant is sodium polyacrylate.

[0025] To achieve the third invention object, the present invention provides the application of a long-lasting and stable slow-release fragrance-releasing and antibacterial microcapsule in the preparation of wood-based panel adhesives or paint films.

[0026] The beneficial effects of adopting the above technical solutions are as follows: The fragrance-releasing and antibacterial microcapsules of the present invention can be widely applied to the adhesive system and paint film system of wood-based panels, achieving a long-lasting and stable slow-release antibacterial and fragrance-releasing effect for wood-based panel products, with an effective period of up to several years; the active substances (such as natural fragrances and antibacterial agents) inside the microcapsules are released gradually, and by utilizing the control performance of the outer shell, their rapid release at the initial stage is avoided, thus ensuring that they can continuously play their effects during long-term use.

[0027] In the adhesive system, the carrier of the microcapsules encapsulates the fragrance and antibacterial components, and these components are slowly released in the glued boards through the degradation or dissolution of the microcapsule outer shell. This can not only achieve the antibacterial effect but also continuously release fragrance, improve the indoor air quality, and increase the added value of wood-based panels; when the wood-based panel is glued and cured, the fragrance and antibacterial components inside the microcapsules will be gradually released during the use of the board. This slow-release characteristic can ensure long-term effective antibacterial and fragrance-releasing effects, extend the service life of the product, and reduce odors.

[0028] In the paint film system, microcapsules can provide a long-lasting and stable antibacterial and aroma release effect through a similar slow-release principle; adding microcapsules to the paint can enable the cured paint film to gradually release antibacterial components and aromas, thereby providing antibacterial protection and fresh aroma for the painted surface.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By using porous carbon microspheres to load natural small-molecule organic essential oils, it has the characteristics of stable spherical structure, high-efficiency loading and high loading capacity. Compared with the traditional microcapsule coating technology, it effectively overcomes the problems of microcapsule damage caused by external stress and low utilization of raw materials during the preparation process.

[0030] (2) Adopt organic-inorganic secondary mineralization to coat the porous carbon microspheres loaded with active substances, layer-by-layer compression from the outside to the inside, reduce the structural damage of the extract components during the short-term high-temperature and high-pressure process, and slowly release the active ingredients of the essential oil through mesoporous and microporous channels to achieve the effects of long-lasting antibacterial and aroma release.

[0031] (3) Due to the existence of the mineralized layer, it ensures that the microspheres can stably exist in some acidic and alkaline environments, making it well applicable to the adhesive system and the surface paint film system during the processing of wood-based panels, enhancing the performance of adhesives and paint films, and endowing certain flame retardant, antibacterial and aroma release functions. Specific embodiments

[0032] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0033] Example 1 A fragrance-releasing and antibacterial microcapsule with long-lasting and stable slow release. Based on the total mass of the microcapsule raw materials being 100%, the components and mass percentages of the raw materials are as follows: 30% of porous carbon microspheres, 30% of small-molecule essential oil, 20% of organic matrix, and 20% of inorganic salt solution; The preparation method of the above-mentioned fragrance-releasing and antibacterial microcapsule with long-lasting and stable slow release includes the following steps: (1) Preparation of porous carbon microspheres: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fiber, straw and plant residues; the animal sources include any one of chitin, animal bones and cutin; the specific preparation process includes: (11) Select wood fiber as the raw material, crush and grind it to obtain uniform fiber powder, and perform chemical pretreatment on it, which usually includes pickling, alkali washing or combined use to remove impurities, hemicellulose and other non-fiber components; Pickling: Mix the fiber powder with hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 1M; Perform pickling at 50°C - 80°C at room temperature or under heating conditions, and the reaction time is usually 1 - 3 hours; Thoroughly wash the fiber with deionized water until the washing liquid is neutral; Dehydrate the pickled fiber, which can be carried out by vacuum filtration or centrifugal separation to remove the excess acid solution; Alkali washing: Mix the fiber powder with sodium hydroxide solution, adjust the pH to about 12, and react at 60 - 90°C under heating conditions for 2 - 4 hours. Wash it repeatedly with deionized water until the pH of the washing liquid is neutral, and then perform dehydration treatment; (12) Mix the obtained pretreatment product (1) evenly with 5% binder polypropylene by mass, and make spherical particles with a diameter in the micron scale through spray drying spheronization technology; (13) Carbonize the obtained product (2) at 500 - 1000°C for 1 - 10 h in nitrogen or argon to obtain porous carbon microspheres with good sphericity, a sphere diameter of 30 - 50 μm, a pore diameter of mesopores of 2 - 50 nm, and a specific surface area of 300 - 1500 m 2 / g; (14) Perform high-temperature steam activation treatment on the reaction product (3). Mainly utilize the reaction of chemical reagents with carbon to break some carbon-carbon bonds of carbon, generate oxides and other chemical products. These products carry away carbon atoms in the carbon, leaving a large number of pores; Chemical reagents usually react with carbon materials to generate volatile products, remove unnecessary impurities in the carbon, and wash and remove residual salts or activators, and then dry to obtain the final porous carbon microspheres; (2) Take 6 g of the porous carbon microspheres prepared in step (1) with a pore diameter of 30 nm, good sphericity, a total pore volume of 0.412 cm 3 / g and a specific surface area of 323 m 2 / g. Dissolve 6 g of agarwood essential oil in a mixed solvent of 102 g of ethanol / deionized water. After mixing with a glass rod, homogenize and disperse it at a speed of 5000 rpm for 10 min using a homogenizer; The mass ratio of small molecule essential oil, ethanol, and deionized water is 1:15:2.

[0034] (3)After the dispersion liquid prepared in step (2) is left standing to defoam, 4 g of sodium alginate solution, 0.2 g of a mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane, and 0.2 g of sodium polyacrylate are added thereto. Then, it is magnetically stirred at 60 °C until all the sodium alginate is dissolved, and homogenously dispersed at 8000 rpm for 15 min; the mass ratio of the mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane is 2:1; (4)After the dispersion liquid prepared in step (3) is left standing to defoam, 4 g of calcium chloride solution is added thereto, and it is mechanically stirred and dispersed at 1000 rpm for 4 h to obtain the product.

[0035] Example 2 A fragrance-releasing and antibacterial microcapsule with long-lasting stability and slow release. Based on the total mass of the microcapsule raw materials being 100%, the components and mass percentages of the raw materials are as follows: porous carbon microspheres 60%, small molecule essential oils 10%, organic matrix 20%, inorganic salt solution 10%; The preparation method of the above-mentioned fragrance-releasing and antibacterial microcapsule with long-lasting stability and slow release includes the following steps: (1) Preparation of porous carbon microspheres: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fibers, straws, and plant residues; the animal sources include any one of chitin, animal bones, and cutin; the specific preparation process includes: (11) Select wood fibers as raw materials, crush and grind them to obtain uniform fiber powder, and perform chemical pretreatment on it, usually including pickling, alkali washing or combined use, to remove impurities, hemicellulose and other non-fiber components; Pickling: Mix the fiber powder with hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 5 M; Perform pickling at 50 °C - 80 °C at room temperature or under heating conditions, and the reaction time is usually 1 - 3 hours; Thoroughly wash the fiber with deionized water until the washing liquid is neutral; Dehydrate the pickled fiber, which can be carried out by vacuum filtration or centrifugal separation to remove the excess acid solution; Alkali washing: Mix the fiber powder with sodium hydroxide solution, adjust the pH to about 12, and react at 60 °C - 90 °C under heating conditions for 2 - 4 hours. Wash it repeatedly with deionized water until the pH of the washing liquid is neutral, and perform dehydration treatment; (12) Mix the obtained pretreatment product (1) evenly with the binder polylactic acid with a mass fraction of 5%, and form spherical particles with a diameter in the micron scale through spray drying and spheronization technology; (13) The obtained product (2) is carbonized in nitrogen or argon at 500 - 1000 °C for 1 - 10 h to obtain porous carbon microspheres with good sphericity, a sphere diameter of 30 - 50 μm, a mesopore diameter of 2 nm - 50 nm, and a specific surface area of 300 - 1500 m 2 / g; (14) The reaction product (3) is subjected to nitrogen activation treatment, mainly by the reaction of chemical reagents with carbon, to break some carbon - carbon bonds in the carbon, generating oxides and other chemical products. These products carry away carbon atoms in the carbon, leaving a large number of pores; chemical reagents usually react with carbon materials to generate volatile products, removing unnecessary impurities in the carbon, and washing to remove residual salts or activators, and then drying to obtain the final porous carbon microspheres; (2) Take 6 g of the porous carbon microspheres prepared in step (1) with a pore diameter of 28 nm, good sphericity, a total pore volume of 0.498 cm 3 / g, and a specific surface area of 417 m 2 / g. Dissolve 1 g of agarwood essential oil in a mixed solvent of 17 g of ethanol / deionized water. After mixing with a glass rod, homogenize and disperse at a speed of 5000 rpm for 10 min using a homogenizer; the mass ratio of the small - molecule essential oil, ethanol, and deionized water is 1:15:2.

[0036] (3) After the dispersion obtained in step (2) is allowed to stand and defoamed, add 2 g of sodium alginate solution, 0.2 g of a mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane, and 0.2 g of sodium polyacrylate thereto. Stir magnetically at 60 °C until the sodium alginate is completely dissolved, and homogenize and disperse at 8000 rpm for 15 min; the mass ratio of the mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane is 2:1; (4) After the dispersion obtained in step (3) is allowed to stand and defoamed, add 1 g of calcium chloride solution thereto, and stir and disperse mechanically at 1000 rpm for 4 h to obtain the product.

[0037] Example 3 A fragrance - releasing and antibacterial micro - capsule with persistent and stable slow - release. Based on the total mass of the micro - capsule raw materials being 100%, the components and their mass percentages in the raw materials are as follows: porous carbon microspheres 50%, small - molecule essential oil 10%, organic matrix 20%, inorganic salt solution 20%; The preparation method of the above-mentioned fragrance-releasing and antibacterial microcapsules with persistent and stable slow release includes the following steps: (1) Preparation of porous carbon microspheres: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fiber, straw and plant residues; the animal sources include any one of chitin, animal bones and cutin; the specific preparation process includes: (11) Select wood fiber as the raw material, crush and grind it to obtain uniform fiber powder, and perform chemical pretreatment on it, usually including pickling, alkali washing or combined use, to remove impurities, hemicellulose and other non-fiber components; Pickling: Mix the fiber powder with hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 3 M; Carry out pickling at 50°C - 80°C at room temperature or under heating conditions, and the reaction time is usually 1 - 3 hours; Wash the fiber thoroughly with deionized water until the washing liquid is neutral; Dehydrate the pickled fiber, which can be carried out by vacuum filtration or centrifugal separation to remove the excess acid solution; Alkali washing: Mix the fiber powder with sodium hydroxide solution, adjust the pH to about 12, and react at 60°C - 90°C under heating conditions for 2 - 4 hours. Wash repeatedly with deionized water until the pH of the washing liquid is neutral, and carry out dehydration treatment; (12) Mix the obtained pretreatment product (1) evenly with 10% binder polypropylene by mass, and make spherical particles with a diameter in the micron scale through spray drying and spheronization technology; (13) Carbonize the obtained product (2) at 500 - 1000°C for 1 - 10 h in nitrogen or argon to obtain porous carbon microspheres with good sphericity, a sphere diameter of 30 - 50 μm, a mesopore diameter of 2 - 50 nm, and a specific surface area of 300 - 1500 m 2 / g; (14) Carry out high-temperature steam activation treatment on the reaction product (3), mainly using the reaction of chemical reagents with carbon to break some carbon-carbon bonds of carbon, generate oxides and other chemical products, and these products carry away carbon atoms in the carbon, leaving a large number of pores; Chemical reagents usually react with carbon materials to generate volatile products, remove unnecessary impurities in the carbon, and wash and remove residual salts or activators, and then dry to obtain the final porous carbon microspheres; (2) Take 5 g of the porous carbon microspheres prepared in step (1) with a pore diameter of 21 nm, good sphericity, a total pore volume of 0.502 cm 3 / g, and a specific surface area of 531 m 2For the porous carbon microspheres of 1 g, dissolve 1 g of agarwood essential oil in a mixed solvent of 17 g of ethanol / deionized water. After mixing with a glass rod, homogenize and disperse it at a speed of 5000 rpm for 10 min using a homogenizer; for the small molecule essential oil, ethanol, and deionized water, the mass ratio is 1:15:2.

[0038] (3) After the dispersion liquid prepared in step (2) is left to stand and defoamed, add 2 g of sodium alginate solution, 4 g of a mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane, and 2 g of sodium polyacrylate thereto. Stir magnetically at 60 °C until all the sodium alginate is dissolved, and homogenize and disperse at 8000 rpm for 15 min; the mass ratio of the mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane is 2:1; (4) After the dispersion liquid prepared in step (3) is left to stand and defoamed, add 2 g of calcium chloride solution thereto, and stir and disperse mechanically at 900 rpm for 3 h to obtain.

[0039] Example 4 A fragrance-releasing and antibacterial microcapsule with persistent stability and slow release. Based on the total mass of the microcapsule raw materials being 100%, the components and mass percentages in the raw materials are as follows: porous carbon microspheres 40%, small molecule essential oil 10%, organic matrix 40%, inorganic salt solution 10%; The preparation method of the above-mentioned fragrance-releasing and antibacterial microcapsule with persistent stability and slow release includes the following steps: (1) Prepare porous carbon microspheres: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fiber, straw, and plant residues; the animal sources include any one of chitin, animal bones, and cutin; the specific preparation process includes: (11) Select wood fiber as the raw material, crush and grind it to obtain uniform fiber powder, and perform chemical pretreatment on it, usually including pickling, alkali washing or combined use to remove impurities, hemicellulose, and other non-fiber components; Pickling: Mix the fiber powder with hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 1 M; Perform pickling at 50 °C - 80 °C at room temperature or under heating conditions, and the reaction time is usually 1 - 3 hours; Wash the fiber thoroughly with deionized water until the washing liquid is neutral; Dehydrate the pickled fiber, which can be carried out by vacuum filtration or centrifugal separation to remove the excess acid solution; Alkali washing: Mix the fiber powder with sodium hydroxide solution, adjust the pH to about 12, react at 60 °C - 90 °C under heating conditions, the reaction time is 2 - 4 hours, wash repeatedly with deionized water until the pH of the water washing liquid is neutral, and perform dehydration treatment; (12) The obtained pretreated product (1) is uniformly mixed with a binder polypropylene with a mass fraction of 5%, and spherical particles with a diameter in the micron scale are made by spray drying and spheronization technology; (13) The obtained product (2) is carbonized in nitrogen or argon at 500 - 1000 °C for 1 - 10 h to obtain porous carbon microspheres with good sphericity, a sphere diameter of 30 - 50 μm, a mesopore diameter of 2 - 50 nm, and a specific surface area of 300 - 1500 m 2 / g; (14) The reaction product (3) is subjected to high-temperature steam activation treatment, mainly using the reaction of chemical reagents with carbon to break some carbon-carbon bonds of carbon, generating oxides and other chemical products. These products carry away carbon atoms in the carbon, leaving a large number of pores; chemical reagents usually react with carbon materials to generate volatile products, removing unnecessary impurities in the carbon, and washing to remove residual salts or activators, and then drying to obtain the final porous carbon microspheres; (2) Take 4 g of the porous carbon microspheres prepared in step (1) with a pore diameter of 18 nm, good sphericity, a total pore volume of 0.687 cm 3 / g and a specific surface area of 582 m 2 / g. Dissolve 1 g of agarwood essential oil in a mixed solvent of 17 g of ethanol / deionized water, mix with a glass rod, and then homogenize and disperse at a speed of 5000 rpm for 10 min using a homogenizer; the mass ratio of the small molecule essential oil, ethanol, and deionized water is 1:15:2.

[0040] (3) After the dispersion liquid prepared in step (2) is allowed to stand and defoamed, add 4 g of sodium alginate, 0.2 g of a mixture of a silane coupling agent isocyanatopropyltriethoxysilane and a silane coupling agent vinyltrimethoxysilane, and 0.2 g of sodium polyacrylate thereto, and stir magnetically at 60 °C until the sodium alginate is completely dissolved, and then homogenize and disperse at 8000 rpm for 15 min; the mass ratio of the mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane is 2:1; (4) After the dispersion liquid prepared in step (3) is allowed to stand and defoamed, add 1 g of calcium chloride solution thereto, and stir and disperse mechanically at 900 rpm for 3 h to obtain.

[0041] Example 5 A fragrance-releasing and antibacterial microcapsule with persistent and stable slow release. Based on the total mass of the microcapsule raw materials being 100%, the components and mass percentages of the raw materials are as follows: porous carbon microspheres 45%, small molecule essential oil 15%, organic matrix 20%, inorganic salt solution 20%; The preparation method of the above-mentioned fragrance-releasing and antibacterial microcapsules with persistent and stable slow release includes the following steps: (1) Preparation of porous carbon microspheres: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fiber, straw and plant residues; the animal sources include any one of chitin, animal bones and cutin; the specific preparation process includes: (11) Select wood fiber as the raw material, crush and grind it to obtain uniform fiber powder, and carry out chemical pretreatment on it, usually including pickling, alkali washing or combined use, to remove impurities, hemicellulose and other non-fiber components; Pickling: Mix the fiber powder with hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 1 M; Carry out pickling at 50°C - 80°C at room temperature or under heating conditions, and the reaction time is usually 1 - 3 hours; Wash the fiber thoroughly with deionized water until the washing liquid is neutral; Carry out dehydration treatment on the pickled fiber, which can be carried out by vacuum filtration or centrifugal separation to remove the excess acid solution; Alkali washing: Mix the fiber powder with sodium hydroxide solution, adjust the pH to about 12, and carry out the reaction at 60°C - 90°C under heating conditions for 2 - 4 hours, wash it repeatedly with deionized water until the pH of the washing liquid is neutral, and carry out dehydration treatment; (12) Mix the obtained pretreatment product (1) evenly with 10% binder polypropylene by mass fraction, and make spherical particles with a diameter in the micron scale through spray drying and spheronization technology; (13) Carbonize the obtained product (2) in nitrogen or argon at 500 - 1000°C for 1 - 10 h to obtain porous carbon microspheres with good spherical shape, a sphere diameter of 30 - 50 μm, a pore diameter of mesopores of 2 - 50 nm, and a specific surface area of 300 - 1500 m 2 / g; (14) Carry out high-temperature steam activation treatment on the reaction product (3), mainly using the reaction of chemical reagents with carbon to break some carbon-carbon bonds of carbon, generate oxides and other chemical products, and these products carry away carbon atoms in the carbon, leaving a large number of pores; Chemical reagents usually react with carbon materials to generate volatile products, remove unnecessary impurities in the carbon, and wash and remove residual salts or activators, and then dry to obtain the final porous carbon microspheres; (2) Take 4.5 g of the porous carbon microspheres prepared in step (1) with a pore diameter of 7 nm, good sphericity, a total pore volume of 0.793 cm 3 / g and a specific surface area of 665 m 2For the porous carbon microspheres of 1.5 g, dissolve 1.5 g of agarwood essential oil in 25.5 g of a mixed solvent of ethanol / deionized water. After mixing with a glass rod, use a homogenizer to homogenize and disperse at a speed of 5000 rpm for 10 min; for the small molecule essential oil, ethanol, and deionized water, the mass ratio is 1:15:2.

[0042] (3) After the dispersion liquid prepared in step (2) is left to stand and defoamed, add 2 g of sodium alginate, 0.2 g of a mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane, and 0.2 g of sodium polyacrylate thereto. Stir magnetically at 60 °C until all the sodium alginate is dissolved, and homogenize and disperse at 8000 rpm for 15 min; the mass ratio of the mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane is 2:1; (4) After the dispersion liquid prepared in step (3) is left to stand and defoamed, add 2 g of calcium chloride solution thereto, and stir and disperse mechanically at 800 rpm for 2 h to obtain.

[0043] Example 6 A kind of fragrance-releasing and antibacterial microcapsule with persistent stability and slow release. Based on the total mass of the microcapsule raw materials being 100%, the components and mass percentages in the raw materials are as follows: porous carbon microspheres 35%, small molecule essential oil 20%, organic matrix 20%, inorganic salt solution 25%; The preparation method of the above-mentioned fragrance-releasing and antibacterial microcapsule with persistent stability and slow release includes the following steps: (1) Prepare porous carbon microspheres: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fibers, straws, and plant residues; the animal sources include any one of chitin, animal bones, and cutin; the specific preparation process includes: (11) Select wood fibers as raw materials, crush and grind them to obtain uniform fiber powder, and perform chemical pretreatment on it, usually including pickling, alkali washing or combined use to remove impurities, hemicellulose, and other non-fiber components; Pickling: Mix the fiber powder with hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 1 M; perform pickling at 50 °C - 80 °C at room temperature or under heating conditions, and the reaction time is usually 1 - 3 hours; wash the fiber thoroughly with deionized water until the washing liquid is neutral; dehydrate the pickled fiber, which can be carried out by vacuum filtration or centrifugal separation to remove the excess acid solution; Alkali washing: Mix the fiber powder with sodium hydroxide solution, adjust the pH to about 12, react at 60 °C - 90 °C under heating conditions, the reaction time is 2 - 4 hours, wash repeatedly with deionized water until the pH of the washing liquid is neutral, and perform dehydration treatment; (12) The obtained pretreated material (1) is uniformly mixed with binder polypropylene with a mass fraction of 5%, and spherical particles with a diameter in the micron scale are formed by spray drying and spheronization technology. (13) The obtained product (2) is carbonized in nitrogen or argon at 500 - 1000 °C for 1 - 10 h to obtain porous carbon microspheres with good sphericity, a sphere diameter of 30 - 50 μm, a mesopore diameter of 2 - 50 nm, and a specific surface area of 300 - 1500 m 2 / g. (14) The reaction product (3) is subjected to high-temperature steam activation treatment. By mainly using the reaction of chemical reagents with carbon, some carbon-carbon bonds of the carbon are broken to generate oxides and other chemical products. These products carry away carbon atoms in the carbon, leaving a large number of pores. Chemical reagents usually react with carbon materials to generate volatile products, removing unnecessary impurities in the carbon, and washing to remove residual salts or activators, and then drying to obtain the final porous carbon microspheres. (2) Take 3.5 g of the porous carbon microspheres prepared in step (1) with a pore diameter of 5 nm, good sphericity, a total pore volume of 0.774 cm 3 / g, and a specific surface area of 633 m 2 / g. Dissolve 2 g of agarwood essential oil in a mixed solvent of 34 g of ethanol / deionized water. After mixing with a glass rod, homogenize and disperse at a speed of 5000 rpm for 10 min using a homogenizer. The mass ratio of small molecule essential oil, ethanol, and deionized water is 1:15:2.

[0044] (3) After the dispersion liquid prepared in step (2) is allowed to stand and defoamed, add 2 g of sodium alginate solution, 4 g of a mixture of silane coupling agent isocyanatopropyltriethoxysilane and silane coupling agent vinyltrimethoxysilane, and 2 g of sodium polyacrylate thereto. Stir magnetically at 60 °C until all the sodium alginate is dissolved, and homogenize and disperse at 8000 rpm for 15 min. The mass ratio of the mixture of silane coupling agent isocyanatopropyltriethoxysilane and silane coupling agent vinyltrimethoxysilane is 2:1. (4) After the dispersion liquid prepared in step (3) is allowed to stand and defoamed, add 2.5 g of calcium chloride solution thereto, and stir and disperse mechanically at 800 rpm for 2 h to obtain the product.

[0045] Comparative Example 1 A fragrance-releasing and antibacterial microcapsule with persistent and stable slow release. Based on the total mass of the microcapsule raw materials being 100%, the components and mass percentages of the raw materials are as follows: porous carbon microspheres 50%, small molecule essential oil 10%, organic matrix 20%, and inorganic salt solution 20%. The preparation method of the above-mentioned fragrance-releasing and antibacterial microcapsules with persistent and stable slow release includes the following steps: (1) Preparation of porous carbon microspheres: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fiber, straw and plant residues; the animal sources include any one of chitin, animal bones and cutin; the specific preparation process includes: (11) Select wood fiber as the raw material, crush and grind it to obtain uniform fiber powder, and carry out chemical pretreatment on it, usually including pickling, alkali washing or combined use, to remove impurities, hemicellulose and other non-fiber components; Pickling: Mix the fiber powder with hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 3 M; Carry out pickling at 50°C - 80°C at room temperature or under heating conditions, and the reaction time is usually 1 - 3 hours; Wash the fiber thoroughly with deionized water until the washing liquid is neutral; Carry out dehydration treatment on the pickled fiber, which can be carried out by vacuum filtration or centrifugal separation to remove the excess acid solution; Alkali washing: Mix the fiber powder with sodium hydroxide solution, adjust the pH to about 12, carry out the reaction at 60°C - 90°C under heating conditions, the reaction time is 2 - 4 hours, wash it repeatedly with deionized water until the pH of the water washing liquid is neutral, and carry out dehydration treatment; (12) Mix the obtained pretreatment product (1) evenly with 5% binder polypropylene by mass fraction, and make spherical particles with a diameter in the micron scale through spray drying and spheronization technology; (13) Carbonize the obtained product (2) at 500 - 1000°C in nitrogen or argon for 1 - 10 h to obtain porous carbon microspheres with good sphericity, a sphere diameter of 30 - 50 μm, a mesopore diameter of 2 - 50 nm, and a specific surface area of 300 - 1500 m 2 / g; (14) Carry out high-temperature steam activation treatment on the reaction product (3), mainly using the reaction of chemical reagents with carbon to break some carbon-carbon bonds of carbon, generate oxides and other chemical products, and these products take away carbon atoms in carbon, leaving a large number of pores; Chemical reagents usually react with carbon materials to generate volatile products, remove unnecessary impurities in carbon, and wash and remove residual salts or activators, and then dry to obtain the final porous carbon microspheres; (2) Take 5 g of the porous carbon microspheres prepared in step (1) with a pore diameter of 21 nm, good sphericity, a total pore volume of 0.502 cm 3 / g and a specific surface area of 531 m 2For the porous carbon microspheres of 1 g, dissolve 1 g of agarwood essential oil in a mixed solvent of 17 g of ethanol / deionized water. After mixing with a glass rod, homogenize and disperse it at a speed of 5000 rpm for 10 min using a homogenizer; for small molecule essential oil, ethanol, and deionized water, the mass ratio is 1:15:2.

[0046] The difference between Comparative Example 1 and Example 3 is that only the emulsified essential oil loading in Step 1 is carried out.

[0047] Comparative Example 2 A fragrance-releasing and antibacterial microcapsule with persistent stability and slow release. Based on the total mass of the microcapsule raw materials being 100%, the components and mass percentages of the raw materials are as follows: porous carbon microspheres 50%, small molecule essential oil 10%, organic matrix 20%, inorganic salt solution 20%. The preparation method of the above-mentioned fragrance-releasing and antibacterial microcapsule with persistent stability and slow release includes the following steps: (1) Prepare porous carbon microspheres: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fiber, straw, and plant residues; the animal sources include any one of chitin, animal bones, and cutin; the specific preparation process includes: (11) Select wood fiber as the raw material, crush and grind it to obtain uniform fiber powder, and carry out chemical pretreatment on it, usually including pickling, alkali washing or combined use to remove impurities, hemicellulose, and other non-fiber components; Pickling: Mix the fiber powder with hydrochloric acid solution, and the concentration of the hydrochloric acid solution is 3 M; Carry out pickling at 50°C - 80°C at room temperature or under heating conditions, and the reaction time is usually 1 - 3 hours; Thoroughly wash the fiber with deionized water until the washing liquid is neutral; Dehydrate the pickled fiber, which can be carried out by vacuum filtration or centrifugal separation to remove the excess acid solution. Alkali washing: Mix the fiber powder with sodium hydroxide solution, adjust the pH to about 12, react at 60°C - 90°C under heating conditions, the reaction time is 2 - 4 hours, wash repeatedly with deionized water until the pH of the washing liquid is neutral, and carry out dehydration treatment. (12) Mix the obtained pretreatment product (1) evenly with 5% binder polypropylene, and make spherical particles with a diameter in the micron scale through spray drying and spheronization technology. (13) Carbonize the obtained product (2) at 500 - 1000°C for 1 - 10 h in nitrogen or argon to obtain porous carbon microspheres with good spherical shape, a sphere diameter of 30 - 50 μm, a pore diameter of mesopores of 2 - 50 nm, and a specific surface area of 300 - 1500 m 2 / g; (14) The reaction product (3) is subjected to high-temperature steam activation treatment, mainly by using the reaction of chemical reagents with carbon to break some carbon-carbon bonds in the carbon, generating oxides and other chemical products. These products carry away carbon atoms in the carbon, leaving a large number of pores. Chemical reagents usually react with carbon materials to form volatile products, remove unnecessary impurities in the carbon, and wash away residual salts or activators, and then dry to obtain the final porous carbon microspheres. (2) Take 5 g of the porous carbon microspheres prepared in step (1) with a pore size of 21 nm, good sphericity, a total pore volume of 0.502 cm 3 / g, and a specific surface area of 531 m 2 / g. Dissolve 1 g of agarwood essential oil in a mixed solvent of 17 g of ethanol / deionized water. After mixing with a glass rod, homogenize and disperse it at a speed of 5000 rpm for 10 min using a homogenizer. The mass ratio of small molecule essential oil, ethanol, and deionized water is 1:15:2.

[0048] (3) After the dispersion obtained in step (2) is allowed to stand and defoamed, add 2 g of sodium alginate solution, 0.2 g of a mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane, and 0.2 g of sodium polyacrylate thereto. Stir magnetically at 60 °C until all the sodium alginate is dissolved, and homogenize and disperse at 8000 rpm for 15 min. The mass ratio of the mixture of the silane coupling agent isocyanatopropyltriethoxysilane and the silane coupling agent vinyltrimethoxysilane is 2:1.

[0049] The difference between Comparative Example 2 and Example 3 is that only the organic layer coating in step 2 is carried out.

[0050] The properties of the products prepared in Examples 1-6 of the present invention and the products of Comparative Examples 1-2 are shown in Table 1: Table 1 Technical parameters of porous carbon microspheres

[0051] It can be seen from Table 1 that: the prepared samples of the examples and comparative examples all have good spherical morphology, the particle size remains at 10-40 μm, and the content of the aroma substances contained remains at 5-30%; the thermal decomposition temperature of the microspheres treated by the organic matrix and inorganic mineralization has been significantly increased and remains at 300-500 °C, while the thermal decomposition temperature of those with only organic matrix coating and without coating has decreased significantly.

[0052] To further illustrate that the porous carbon microspheres of the present invention have high temperature resistance, high pressure resistance, fragrance release, and antibacterial effects, samples of Examples 1-6 and Comparative Examples 1-2 were respectively added to the glue for impregnated film paper, and the addition amount was 0.5% of the adhesive. After the impregnated film paper was impregnated for 30 s, dried in an oven at 105 °C for 10 min, and then pasted on the ecological board, hot-pressed at 180 °C for 10 min, and left for 30 days, antibacterial tests were carried out. The results are shown in Table 3; referring to the forestry industry standard LY / T 3236-2020 "Classification and Evaluation Method of Odors of Wood-Based Panels and Their Products", after the samples treated by accelerated slow release at 60 °C for different times were enriched in a dryer for 24 h, the olfactory personnel used the method of manual olfaction to conduct sensory grading of the odors, and the fragrance release scores were recorded at a fixed location and time. The number of repeated specimens for each condition was 3, and 3-4 olfactory personnel participated. The results were averaged. This method can be used to guide the evaluation of fragrance release in a closed space, as shown in Table 2; Table 2 Test Results of Fragrance Release Performance of Porous Carbon Microspheres Used in Ecological Boards

[0053] It can be seen from the data in Table 2 that the porous carbon microspheres prepared in Examples 1-6 still had obvious woody and floral scents after being used in ecological boards and accelerated slow release at 60 °C for 480 h. For Comparative Example 1, the sample prepared from porous carbon microspheres only loaded with antibacterial essential oil had significantly weakened woody and fragrant scents, only reaching 0.3 level; for the sample prepared from porous carbon microspheres coated with an organic layer in Comparative Example 2, the slow release effect was better than that of Comparative Example 1, but inferior to Examples 1-3.

[0054] Table 3 Test Results of Antibacterial Activity of Porous Carbon Microspheres Used in Ecological Boards

[0055] It can be seen from the data in Table 3 that the porous carbon microspheres prepared in Examples 1-6 still had the effects of resisting Escherichia coli E. coli and Staphylococcus aureus S. aureus after being used in ecological boards; it can be seen from Comparative Examples 1-2 that the antibacterial effect of the ecological board prepared from porous carbon microspheres only loaded with antibacterial essential oil was significantly weakened; and the antibacterial performance of the porous carbon microspheres coated with an organic layer was improved, but still lower than that of the porous carbon microspheres after organic-inorganic mineralization.

[0056] In summary, the present invention provides a preparation method of a porous carbon microcapsule with good pressure resistance, heat resistance, corrosion resistance, and high-load natural active fragrance release and antibacterial substances with persistent and stable slow release. The bio-based porous carbon microspheres are used to load natural small molecule essential oils, and organic-inorganic mineralization coating on the surface is realized through an organic matrix and an inorganic salt solution to improve the hardness, heat resistance, corrosion resistance, etc. of the microsphere particles and the persistent and stable slow release of fragrance release and antibacterial active substances, which can be applied to the production process of wood-based panel adhesives.

Claims

1. A long-lasting, stable and sustained-release antibacterial microcapsule, characterized in that: Calculated by mass percentage, it includes the following components: Porous carbon microspheres 30-60%, small molecule essential oils 10-30%, organic matrix 20-50% and inorganic salt solution 10-30%.

2. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 1 are characterized in that: The porous carbon microspheres are bio-based porous carbon microspheres, which are prepared by carbonizing organic precursors; the organic precursors include plant sources rich in cellulose or animal sources rich in organic matter; the plant sources include any one of wood fibers, straws and plant residues; the animal sources include any one of chitin, animal bones and cuticles.

3. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 2 are characterized in that: The porous carbon microspheres are prepared by the following method: (11) crushing and grinding the plant source or animal source, and then acid washing and / or alkali washing to obtain pretreated product I; (12) adding a binder to the pretreated product I, mixing them evenly, and then spheroidizing them to obtain spherical particles with a diameter in the micrometer scale, thereby obtaining a pretreated product II; (13) The pretreated product II is then carbonized in nitrogen or argon at 500-1000°C for 1-10 hours to obtain a spherical material with a spherical diameter of 30-50 μm, a mesopore diameter of 2-50 nm, and a specific surface area of ​​300-1500 m 2 / g porous carbon microspheres; (14) The porous carbon microspheres are then activated and dried to obtain the final porous carbon microspheres.

4. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 3 are characterized in that: The pickling agent is hydrochloric acid or sulfuric acid, the pickling agent concentration is 1-5M, and the reaction time is 1-3 hours; The alkaline washing agent is sodium hydroxide or potassium hydroxide; the reaction pH value is 11-12, the reaction temperature is 60-90° C., and the reaction time is 2-4 hours.

5. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 3 are characterized in that: The addition amount of the binder is 5-30%; the binder includes any one or a mixture of several of polypropylene, polyethylene, polylactic acid, starch, gum arabic and gelatin.

6. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 3 are characterized in that: The spheroidization treatment includes wet spheroidization, spray drying spheroidization, extrusion molding, spheronization, oscillation spheroidization or spray cooling spheroidization.

7. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 3 are characterized in that: The activation treatment includes physical activation and / or chemical activation; the physical activation includes high-temperature steam or nitrogen activation; the reagent used for the chemical activation includes sodium hydroxide, potassium hydroxide or hydrogen peroxide.

8. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 1 are characterized in that: The small molecule essential oil is an oil compound extracted from a plant, and its molecular weight is less than 300; the plant is any one of mint, tea tree, rosemary, thyme and eucalyptus.

9. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 1 are characterized in that: The organic matrix is ​​polysaccharide or protein, including any one of gelatin, sodium alginate, hyaluronic acid and carboxyl cellulose.

10. The long-lasting, stable and sustained-release antibacterial microcapsules according to claim 1 are characterized in that: The inorganic salt solution is a cationic solution, including any one of sodium chloride, copper sulfate, potassium nitrate, sodium carbonate or calcium chloride.

11. A method for preparing the long-lasting, stable and sustained-release antibacterial microcapsules according to any one of claims 1 to 10, characterized in that: include: The formulated amount of small molecule essential oil is loaded on the porous carbon microspheres, and then the organic matrix and the inorganic salt solution are coated on the porous carbon microspheres loaded with the small molecule essential oil in turn to obtain the long-lasting, stable and sustained-release aroma-releasing antibacterial microcapsules.

12. The method for preparing the long-lasting, stable and sustained-release antibacterial microcapsules according to claim 11, characterized in that: include: (1) Preparation of porous carbon microspheres; (2) mixing the porous carbon microspheres, small molecule essential oil, deionized water and ethanol, and uniformly dispersing them at 5000-8000 r / min for 2-10 min to obtain porous carbon microspheres loaded with small molecule essential oil; the mass ratio of the porous carbon microspheres, small molecule essential oil, deionized water and ethanol is 1:0.1-1:1-3:10-20; (3) adding 20-50% by mass of an organic matrix solution to the product obtained in step (2), and then adding 0.5-1.5% by mass of a coupling agent and 0.5-1.5% by mass of a dispersant, mixing, stirring until the organic matrix is ​​completely dissolved, and then homogenizing and dispersing at 5000-8000 r / min for 5-15 minutes; (4) Adding 10-30% by mass of an inorganic salt solution to the product obtained in step (3), stirring and dispersing at 800-1000 r / min for 2-4 h, filtering and drying, to obtain a long-lasting, stable, sustained-release, antibacterial microcapsule with an organic-inorganic mineral layer as the surface shell.

13. The method for preparing the long-lasting, stable and sustained-release antibacterial microcapsules according to claim 12, characterized in that: The coupling agent is a mixture of silane coupling agent isocyanate propyl triethoxysilane and silane coupling agent vinyl trimethoxysilane, with a mass ratio of 2:1; the dispersant is sodium polyacrylate.

14. Use of the long-lasting, stable and sustained-release aroma-releasing antibacterial microcapsules according to any one of claims 1 to 10 in the preparation of adhesives or paint films for artificial boards.

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