Fragrance microcapsule emulsion production process

Abstract

The invention discloses a production process of a fragrance microcapsule emulsion. The fragrance microcapsule emulsion has long-acting slow release, antibacterial performance and material compatibility. The process comprises three steps of oil phase preparation, water phase preparation and emulsification, a fragrance additive compounded by sandalwood, agilawood grease, kapur and pepper essential oil is wrapped in a microcapsule wall material formed by crosslinking isophorone diisocyanate and Arabic gum polysaccharide, and the microcapsule is prepared through an oil phase-water phase emulsification-crosslinking synergistic process. In the oil phase, isophorone diisocyanate and the fragrance additive are mixed in proportion, and the crosslinking density is regulated and controlled; the aqueous phase takes an Arabic gum aqueous solution as a continuous phase, and polysaccharide components such as D-galactose and L-arabinose stabilize the emulsion through hydrogen bonds, electrostatic repulsion and hydrophobic interaction; mixing, homogenizing dispersion and emulsion liquefaction reaction are controlled in stages in the emulsification process, and xylitol is added to adjust viscosity, synergistically inhibit bacteria and assist cross-linking; the final finished product comprises 10-20% of a core material, 5-15% of a wall material, 50-70% of a continuous phase and 1-3% of xylitol.

Description

Technical Field

[0001] The present invention relates to the technical fields of materials science and chemical engineering, and particularly to a production process of a fragrance emulsion based on microcapsule technology. Background Art

[0002] In the fields of interior decoration and furniture manufacturing, ecological boards have attracted much attention due to their environmental protection and functionality. Traditional fragrance-type boards mostly achieve odor improvement by directly adding fragrances or adsorbing spices, but there are problems such as too fast fragrance release, insufficient persistence, limited antibacterial effect, and being easily affected by environmental temperature and humidity. In addition, the single fragrance function is difficult to meet the composite requirements of long-lasting fragrance and health functions in home and public environments. Although microcapsule technology has been introduced to delay fragrance release, the existing processes still have significant defects: one is that the low core material encapsulation rate leads to easy loss of active ingredients; the second is the uneven dispersion of microcapsules, which affects the uniformity and stability of the coating; the third is that the synergistic effect between fragrance components and antibacterial agents (such as nano silver) has not been fully explored, resulting in limited function superposition effect. In conventional microcapsule preparation, improper selection of cross-linking agents easily causes the capsule wall to be fragile, and unreasonable design of the emulsion system leads to phase separation or too wide particle size distribution. These problems restrict the practicality and market competitiveness of fragrance antibacterial boards. Summary of the Invention

[0003] The purpose of the present invention is to provide an efficient and stable production process of a fragrance microcapsule emulsion, so as to balance long-term slow release, antibacterial performance and material compatibility, and meet the dual requirements of modern homes for health and sensory experience.

[0004] The production process of the fragrance microcapsule emulsion provided by the present invention realizes functions of fragrance slow release, stability improvement, antibacterial function integration and compatibility optimization through the synergistic effect of oil phase-aqueous phase emulsification-crosslinking reaction. The process of the present invention encapsulates fragrance essential oils in microcapsules to delay volatilization and extend the persistence of fragrance; forms a uniform and stable emulsion system to avoid oxidation or phase separation of fragrance components; combines the antibacterial characteristics of natural essential oils and the physical barrier effect of microcapsules to endow the emulsion with antibacterial properties; is applicable to application scenarios such as ecological board coatings, and meets the composite requirements of environmental protection and function.

[0005] The present invention provides a production process of a fragrance microcapsule emulsion, which specifically includes the following steps: Preparation of oil phase: Each fragrance essential oil is mixed evenly in proportion to form the main component of the fragrance additive, and then evenly mixed with isophorone diisocyanate again at a ratio of 1:1 - 3:1 to obtain a mixed oil phase. On the one hand, the preparation of the oil phase integrates the fragrance active ingredients, such as mixing sandalwood essential oil and agarwood resin essential oil in proportion to form a fragrance additive with specific aroma levels and antibacterial functions. On the other hand, it also includes the introduction of crosslinking precursors. Isophorone diisocyanate is used as the wall material precursor, which will undergo interfacial polymerization with arabic gum polysaccharide in the aqueous phase later to form the microcapsule wall. Among them, the proportion of the fragrance essential oil ensures the synergistic balance between the aroma intensity and the antibacterial effect, and the ratio of isophorone diisocyanate to the fragrance additive regulates the crosslinking density, affecting the compactness of the microcapsule wall and the core material encapsulation rate.

[0006] Preparation of aqueous phase: Dissolve arabic gum in 15 - 25 times the mass of water and stir until completely dissolved to make the aqueous phase. On the one hand, the preparation of the aqueous phase constructs the emulsification system. Arabic gum, as a natural emulsifier, reduces the oil-water interfacial tension through the synergistic action of its polysaccharide and protein to stabilize the emulsion. On the other hand, it provides crosslinking reaction sites. The hydroxyl groups in arabic gum react with the isocyanate groups of isophorone diisocyanate to form a polyurethane / polyurea crosslinking network, constituting the microcapsule wall. Among them, the ratio of arabic gum to water balances the solution viscosity and emulsification efficiency, avoiding excessive thickening that affects the dispersion uniformity.

[0007] Emulsification process: Slowly add the mixed oil phase into the aqueous phase. After preliminary stirring, homogenize it at a speed of 4000 - 10000 rpm for 5 - 15 minutes, then heat and stir the mixture for 1 - 3 hours for the emulsification reaction to form the fragrance microcapsule emulsion. On the one hand, the emulsification process shapes the microcapsule structure. The oil phase is dispersed into tiny droplets through high-shear homogenization, and arabic gum, as a water-soluble emulsifier, forms an O / W emulsion to form a "water-in-oil" emulsion template. On the other hand, it completes the crosslinking reaction. Heating promotes the interfacial polymerization of isophorone diisocyanate and arabic gum polysaccharide to solidify the microcapsule wall. At the same time, it optimizes the emulsion stability. The addition of xylitol aqueous solution enhances the long-term stability of the emulsion through adjusting the osmotic pressure or hydrogen bond interaction. Among them, the homogenization speed and time control the microcapsule particle size (target 1 - 10 μm). The smaller the particle size, the larger the specific surface area but the higher the compactness of the wall material, the slower the long-term slow-release rate, but the higher the dispersion stability. The reaction temperature and time ensure the completion of the crosslinking reaction, avoiding the residue of unreacted isophorone diisocyanate that affects safety. In the water-in-oil (O / W) emulsion, the oil phase is the dispersed phase and the aqueous phase is the continuous phase. Arabic gum, as a natural emulsifier, can reduce the oil-water interfacial tension, making the oil phase evenly dispersed in the aqueous phase in the form of tiny droplets. This emulsion system has good stability and slow-release performance and is suitable for the preparation of fragrance microcapsules.

[0008] In the production process of the present invention, the functions of fragrance, antibacterial, and slow release are naturally integrated through process design, reducing the need for additional additives; the use of natural ingredients (such as gum arabic) and controllable cross-linking reactions meets the standards of ecological materials; the performance of microcapsules is precisely regulated by parameter optimization (such as rotation speed, temperature) to adapt to diverse application scenarios. Isophorone diisocyanate is a commonly used isocyanate compound, which often reacts with compounds containing hydroxyl or amino groups to form polyurethane or polyurea structures and is used in the present invention for the formation of the microcapsule wall. Gum arabic contains rich polysaccharides and proteins and has good emulsifying properties, which helps to stabilize the oil-water interface. High-speed homogenization helps to reduce the size of oil droplets and form a more uniform emulsion, while heating and stirring promote the completion of chemical reactions and help isophorone diisocyanate react with the hydroxyl groups in gum arabic to cross-link and form the microcapsule wall.

[0009] In the production process of the fragrance microcapsule emulsion of the present invention, the oil phase includes isophorone diisocyanate and a fragrance additive in a mass ratio of 1:1 - 3, and the composition of the fragrance additive includes, by mass percentage: 50 - 70% sandalwood essential oil, 10 - 20% agarwood essential oil, 10 - 20% borneol essential oil, and 5 - 10% pepper essential oil.

[0010] As a cross-linking agent, isophorone diisocyanate undergoes an interfacial polymerization reaction with the polysaccharide hydroxyl groups in gum arabic to form a polyurethane / polyurea cross-linking network, constituting a dense wall material for the microcapsules, which is a practical wall material precursor; the ratio of isophorone diisocyanate to the fragrance additive affects the cross-linking density and regulates the mechanical properties. The higher the ratio, the harder the wall material and the higher the core material encapsulation rate, but the flexibility is reduced; it can also provide chemical stability to prevent the fragrance essential oil from losing efficacy due to oxidation or excessive volatilization.

[0011] The fragrance additive includes sandalwood essential oil, agarwood essential oil, borneol essential oil, and pepper essential oil, forming a four-dimensional fragrance note of "wood - smoky - cool - spicy". Sandalwood and borneol act against bacteria, pepper acts against molds, and agarwood aids in antioxidant, achieving the composite functions of broad-spectrum antibacterial + aroma slow release + system stability. The high-boiling sandalwood essential oil (>250°C) delays volatilization, and borneol (boiling point about 204°C) and pepper (low-boiling components) regulate the release gradient to extend the aroma persistence. Among them, sandalwood essential oil is the main source of fragrance, providing a deep and persistent woody aroma and laying the foundation for the fragrance note; it contains terpene compounds such as α-santalol, and the content of its sesquiterpene compounds is 40 - 80%, accounting for 50 - 70% in the additive, and inhibits the growth of microorganisms by destroying the cell membrane of bacteria (such as Escherichia coli, Staphylococcus aureus), playing an antibacterial function; the high proportion ensures the dominant position of the aroma intensity and antibacterial effect, but the volatilization rate and slow release performance need to be balanced. Sandalwood essential oil is extracted and distilled from the heartwood of mature sandalwood and white sandalwood trees over 40 years old, and after being stored for half a year, it reaches a rich and sweet smell, having the effects of calming the mind, promoting well-being, preventing and treating diseases, and treating anxiety, depression, and insomnia.

[0012] As an aroma synergist, agarwood essential oil imparts a smoky and resinous scent to the fragrance, enhancing the layering and complexity; the sesquiterpenoid content is 60 - 90%, accounting for 10 - 20% in the additives. The sesquiterpenoids in agarwood can delay the oxidation of the fragrance, improve the stability of the emulsion, and assist in antioxidant effects. As a "blending agent", it compensates for the singularity of sandalwood essential oil and at the same time aids in the extension of functions. Agarwood essential oil is the resin produced after the Aquilaria sinensis tree is injured. It is a wonderful substance for nourishing the heart and calming the mind, cultivating one's temperament, and inspiring spiritual thinking. Its scent has strong penetrability and has the effects of promoting qi circulation to relieve pain, warming the middle-jiao to stop vomiting, and accepting qi to relieve asthma.

[0013] Dryobalanops aromatica essential oil provides a cool feeling and diffusibility. Borneol (borneol) has volatile cooling properties, accelerating the diffusion of fragrance molecules; by inhibiting the activity of microbial enzymes, it synergistically enhances the antibacterial effect with sandalwood essential oil to achieve anti-corrosion and efficiency enhancement; it enhances the freshness and spatial penetrability of the fragrance, and at the same time strengthens the antibacterial performance. Dryobalanops aromatica essential oil is the resin of the plant Dryobalanops aromatica in the family Dipterocarpaceae. Extracted from Dryobalanops aromatica resin and volatile oil, its main component is dextrorotatory borneol, with a content greater than 80%, which has the effects of refreshing the mind, antibacterial and anti-inflammatory, improving respiration, and promoting digestion.

[0014] As a pungent fragrance modifier, pepper essential oil provides a slight pungency, enriching the sensory dimension of the fragrance; it contains capsaicinoid substances, with a piperine content greater than 2%, accounting for 5 - 10% in the additives. It has an inhibitory effect on molds and Gram-negative bacteria (such as Pseudomonas aeruginosa), with broad-spectrum antibacterial properties; a low proportion avoids odor conflicts, but broadens the functional coverage through specific antibacterial effects. Pepper essential oil is an essential oil extracted from Piper sarmentosum. It has a unique smell, with an obvious fresh feeling of herbaceous plants, a faint woody fragrance, and a fruity fragrance, which can relax the body and mind. It is very suitable for aromatherapy and massage, and has the effects of refreshing the mind and improving cold constitution.

[0015] The core function of the aqueous phase in the present invention is to construct a stable microcapsule emulsion system through the synergistic effects of the emulsification and crosslinking of gum arabic, achieving emulsion stability, wall material crosslinking, system regulation, and functional compatibility. Among them, gum arabic, as a natural emulsifier, reduces the interfacial tension between oil and water, forming uniformly dispersed emulsion droplets; the polysaccharides in gum arabic react with isophorone diisocyanate in the oil phase through interfacial polymerization to form a dense microcapsule wall material; through the hydrogen bond or electrostatic interaction of the polysaccharide chain, the viscosity and long-term stability of the emulsion are maintained to prevent phase separation; the natural properties of the polysaccharide cooperate with fragrance essential oil and xylitol, taking into account environmental protection and functionality (such as antibacterial and slow release).

[0016] In the production process of the perfume microcapsule emulsion of the present invention, the aqueous phase comprises gum arabic and water with a mass ratio of 1:15 - 25. The gum arabic comprises protein and polysaccharide with a mass ratio of 2 - 25:75 - 98. The polysaccharide component comprises D-galactose, L-arabinose, D-glucuronic acid, L-rhamnose and 4-O-methyl-D-glucuronic acid with a mass ratio of 30 - 50:20 - 30:10 - 20:10 - 15:1 - 3. This specific combination optimizes the stability of the emulsification system and the compactness of the microcapsule wall.

[0017] Gum arabic is a protein-polysaccharide complex, in which the protein accounts for 2 - 25%. As a surfactant, it adsorbs on the oil-water interface, reduces the surface tension, promotes the dispersion of the oil phase into tiny droplets, and at the same time assists in emulsification, forming an interfacial film synergistically with the polysaccharide to enhance the anti-coalescence ability of the droplets. The polysaccharide accounts for 75 - 98%. As the main body of the cross-linking reaction, the hydroxyl groups (-OH) in the polysaccharide react with the isocyanate groups (-NCO) of IPDI to generate a polyurethane / polyurea cross-linking network, which constitutes the microcapsule wall material. At the same time, rheological regulation is carried out. The polysaccharide chains form a three-dimensional network structure through hydrogen bonds, increasing the viscosity of the emulsion and inhibiting the sedimentation of droplets. The polysaccharide of gum arabic forms a stable three-dimensional network through its complex molecular structure (such as the hydroxyl groups of D-galactose providing hydrogen bond cross-linking and the carboxylic acid groups of D-glucuronic acid causing electrostatic repulsion), reducing the oil-water interface tension and inhibiting droplet coalescence; the branched-chain structure of L-arabinose produces a steric hindrance effect to prevent droplet contact; the hydrophobic group of L-rhamnose enhances the oil-phase coating ability, and at the same time cross-links with isophorone diisocyanate (IPDI) to form a dense polyurethane / polyurea wall material. Finally, through physical barrier and chemical bonding, the emulsification stability and the compactness of the microcapsule wall are synergistically improved. Among the polysaccharide components, D-galactose is a neutral sugar containing multiple hydroxyl groups, providing cross-linking sites, enhancing the mechanical strength of the wall material, regulating the viscosity of the emulsion, and optimizing the dispersion stability. D-galactose dominance ensures sufficient cross-linking sites and mechanical strength; L-arabinose is a pentose with a branched-chain structure, increasing the flexibility of the polysaccharide chain, avoiding brittle cracking of the wall material, and inhibiting droplet aggregation through steric hindrance; D-glucuronic acid contains a carboxylic acid group (-COOH), reacting with isophorone diisocyanate to generate a more stable amide bond, and the ionization of the carboxylic acid group enhances the electrostatic stability of the emulsion; L-rhamnose is a methylated hexose with hydrophobic modification, enhancing the interfacial affinity of the polysaccharide, promoting oil-phase coating, enhancing the hydrophobicity of the wall material, and delaying the volatilization of the core material; 4-O-methyl-D-glucuronic acid is a methylated glucuronic acid, regulating the reaction activity, avoiding over-cross-linking resulting in too thick wall material, and the methyl group enhances the thermal stability of the polysaccharide; L-rhamnose and methylglucuronic acid balance the hydrophobicity and reaction activity of the wall material to prevent core material leakage. Water serves as a dissolution and dispersion medium, dissolving gum arabic to form a continuous phase, providing the water environment required for the reaction, and at the same time serving as a heat transfer medium to promote the completion of the cross-linking reaction in the heating stage.

[0018] In the present invention, the aqueous phase constructs the core framework of the microcapsule emulsion through the protein emulsification of gum arabic and the chemical cross-linking function of polysaccharides. The proportion design of each polysaccharide component not only ensures the mechanical properties and stability of the wall material, but also optimizes the functional adaptability through chemical modifications such as methylation. The green cross-linking process of natural polysaccharides and isophorone diisocyanate avoids the toxicity risk of synthetic emulsifiers; the fine ratio of polysaccharide components achieves the balance of "strong wall material - high stability - slow-release function".

[0019] In the present invention, the design of the mass ratio of the oil phase to the aqueous phase (1:3 - 5) optimizes the emulsification efficiency through the dynamic balance of the oil and aqueous phases, ensures the integrity of the microcapsule structure, and realizes the balance between function and cost. This ratio ensures that the oil phase is fully dispersed into tiny droplets to form a uniform and stable emulsion template; regulates the cross-linking reaction rate and the wall material thickness to ensure the efficient encapsulation of the core material; while ensuring the fragrance loading amount, it avoids waste of raw materials or complication of the process caused by excessive oil phase; balances the core material loading amount and the emulsification stability to prevent demulsification caused by emulsion overload. The aqueous phase functions as an emulsifying medium, provides an adequate continuous phase (gum arabic solution) to wrap the oil phase droplets and prevent coalescence; at the same time, the aqueous phase provides a necessary water environment for the interfacial polymerization reaction and serves as a heat transfer medium; a high proportion of the aqueous phase dilutes the oil phase concentration, reduces the droplet collision frequency, and inhibits emulsion stratification.

[0020] The mass ratio of the oil phase to the aqueous phase (1:3 - 5) in the present invention is one of the core parameters of the process design, which directly affects the emulsification stability, microcapsule performance, and function realization. If this mass ratio is too high, the fragrance loading amount is high and the aroma intensity is significant, but the emulsification difficulty increases and large droplets are likely to appear; if it is too low, the emulsion stability is the best and suitable for long-term storage, but the fragrance slow-release rate is too fast and the functionality decreases. This oil phase ratio (1:1 - 3:1) affects the mechanical strength and core material encapsulation rate of the microcapsule by regulating the cross-linking density.

[0021] In the production process of the fragrance microcapsule emulsion of the present invention, the mass ratio of the oil phase to the aqueous phase is 1:3 - 5. The oil phase is the carrier of the fragrance essential oil. If the ratio is too low, it will lead to insufficient fragrance concentration, affecting the aroma intensity and persistence; isophorone diisocyanate needs to react with gum arabic polysaccharides to form the wall material. Too low an oil phase ratio limits the cross-linking density, resulting in a loose wall material.

[0022] The emulsification process of the present invention realizes the precise formation of the microcapsule structure, the optimization of emulsion stability, and the integration and enhancement of functions by controlling the mixing, dispersion, and reaction conditions in stages. Through the emulsification process of the present invention, fragrance microcapsules with uniform particle size and dense wall material are formed to ensure the efficient encapsulation and slow release of the core material; through the synergistic action of physical dispersion and chemical cross-linking, phase separation or stratification during storage is avoided; combined with fragrance slow release, antibacterial properties, and material compatibility, it meets the application requirements such as the coating of ecological boards.

[0023] In the production process of the fragrance microcapsule emulsion of the present invention, the emulsification process specifically includes the following steps: S3.1 Oil-water phase mixing: Add the mixed oil phase to the water phase at a rate of 1-3 mL / min, and stir preliminarily for 5-15 minutes to make the oil and water mix evenly; Preliminary emulsification is achieved by slowly adding the oil phase (1-3 mL / min) and stirring to form the prototype of an "oil-in-water" emulsion, avoiding droplet coalescence; Interface pre-reaction occurs when isophorone diisocyanate (IPDI) in the oil phase comes into initial contact with gum arabic polysaccharide in the water phase, initiating the interfacial polymerization reaction; The addition rate (1-3 mL / min) controls the dispersion speed of the oil phase. If it is too fast, it is easy to cause local overload and form large droplets. If it is too slow, the production efficiency will be reduced; The stirring time (5-15 minutes) ensures sufficient contact between the oil and water phases, but avoids long-term stirring from causing pre-crosslinking and affecting the subsequent homogenization effect. In the present invention, the role of gum arabic is to reduce the oil-water interfacial tension through the synergistic effect of its polysaccharide and protein, forming a stable oil-in-water emulsion. This emulsion system can not only effectively encapsulate the fragrance essential oil, but also further improve the stability and slow-release performance of the emulsion through the cross-linking reaction of the microcapsule wall material.

[0024] S3.2 Homogenization and dispersion: Homogenize the solution at a rotation speed of 4000-10000 rpm for 5-15 minutes to ensure the uniform dispersion of the essence and the encapsulating material; Droplet refinement: The oil phase is broken into micron-sized droplets (target 1-10 μm) by high shear force (4000-10000 rpm), increasing the specific surface area and promoting the subsequent cross-linking reaction; Eliminate the local concentration gradient to ensure the uniform distribution of the fragrance essential oil and isophorone diisocyanate inside the droplets; The rotation speed is 4000-10000 rpm. The higher the rotation speed, the smaller the droplet size and the slower the slow-release rate, but the energy consumption and equipment requirements increase; The time (5-15 minutes) balances the refinement effect and the thermal effect. High-speed friction will cause temperature rise, and premature cross-linking needs to be avoided.

[0025] S3.3 Emulsification reaction: Heat the mixed solution to 40 - 60 °C, add the xylitol aqueous solution while stirring at 300 - 1000 rpm, raise the temperature to 60 - 80 °C and react for 1 - 3 hours to form an aroma microcapsule emulsion; heat to 60 - 80 °C to accelerate the interfacial polymerization reaction between isophorone diisocyanate and arabic gum polysaccharide to form a stable polyurethane / polyurea wall material and achieve crosslinking and curing; the addition of the xylitol aqueous solution enhances the performance through the synergistic effects of the stabilizer function, antibacterial assistance, and reaction regulation, adjusts the rheological properties of the emulsion, prevents sedimentation during storage, inhibits microbial sugar metabolism, and synergistically inhibits bacteria with the aroma essential oil. At the same time, its hydroxyl group can react with the residual groups of isophorone diisocyanate to reduce free toxic substances; through the temperature gradient from 40 - 60 °C to 60 - 80 °C, the low-temperature stage (40 - 60 °C) avoids droplet rupture caused by violent reactions, and the high-temperature stage (60 - 80 °C) ensures complete crosslinking; the stirring speed of 300 - 1000 rpm maintains the dynamic stability of the emulsion and prevents microcapsule sedimentation or aggregation; an excessive amount of xylitol added increases the system viscosity and hinders mass transfer; if it is insufficient, the functional assistance effect is limited. The combination of the heating temperature (40 - 80 °C), stirring speed (300 - 1000 rpm), and homogenization speed (4000 - 10,000 rpm) can improve the uniformity and stability of the microcapsules through synergistic effects.

[0026] The design of the stage parameters (such as rotation speed, temperature) of the emulsification process of the present invention accurately controls the microcapsule particle size and the compactness of the wall material; using natural polysaccharide (arabic gum) and low-toxic crosslinking agent (isophorone diisocyanate) reduces the dependence on synthetic auxiliaries, which is green and efficient; through process design, the aroma slow release, antibacterial, and stability are naturally integrated, avoiding the addition of functional components. Among them, the mass ratio of the oil-water phase of 1:3 - 5 is adapted to the process. The high water phase ratio (3 - 5 parts) provides an adequate dispersion medium, matches the high rotation speed requirement of homogenization, and ensures the effect of droplet refinement; the low oil phase ratio (1 part) requires precise control of the mixing rate to avoid local overload; xylitol is added during the reaction stage, which not only participates in the crosslinking side reaction but also inhibits the growth of microorganisms through osmotic pressure, achieving "multiple effects with one agent".

[0027] In the present invention, the concentration and addition amount of the xylitol aqueous solution synergistically optimize the emulsion performance through physical stability, chemical assistance, and biological antibacterial aspects, and its action mechanism is deeply coupled with process parameters (temperature, rotation speed). As a plant extract, xylitol meets the ecological material standards and realizes the triple functions of stability, antibacterial property, and safety through a single additive, reducing the use of additional auxiliaries and lowering costs. The hydroxyl group (-OH) of xylitol can combine with the unreacted isophorone diisocyanate group (-NCO) to reduce free toxic substances; its molecules regulate the viscosity of the aqueous phase through hydrogen bonding, reduce the interfacial tension, and promote the uniform dispersion of the oil and water phases; in addition, xylitol reduces the water activity through osmotic pressure and interferes with the sugar metabolism of microorganisms, and synergistically enhances the antibacterial effect with the antibacterial components of the fragrance essential oil, having both chemical assistance and biological function enhancement effects. The xylitol aqueous solution acts as a stabilizer and antibacterial synergist to assist the cross-linking reaction. Among them, the hydroxyl group (-OH) in the xylitol molecule forms a hydrogen bond with water, increasing the viscosity of the system, delaying the sedimentation or aggregation of microcapsules, regulating the rheology of the emulsion, and enhancing the storage stability; the density difference between the oil and water phases is balanced through osmotic pressure, reducing the risk of stratification and inhibiting phase separation. Xylitol cannot be metabolized by most bacteria, interfering with sugar metabolism and causing microbial energy depletion, and synergistically inhibiting the growth of bacteria and molds with the antibacterial components of the fragrance essential oil (such as santalol, capsaicin); by binding free water molecules, the water activity is reduced, inhibiting the microbial reproduction environment. At the same time, the hydroxyl group of xylitol combines with the residual group (-NCO) of unreacted isophorone diisocyanate, reducing free toxic substances and improving the safety of the product.

[0028] In the production process of the fragrance microcapsule emulsion of the present invention, the mass concentration of the xylitol aqueous solution is 2-10%, and the addition amount of the xylitol aqueous solution is 5-15% of the total liquid mass.

[0029] The low-concentration xylitol aqueous solution of 2-5% mainly regulates the viscosity to avoid excessive thickening affecting the dispersion uniformity; the high concentration of 5-10% significantly enhances the antibacterial effect and the system stability, but it should be noted that too high viscosity may cause emulsification difficulties or a decrease in the permeability of the microcapsule wall material. The addition amount of the xylitol aqueous solution accounts for 5-15% of the total liquid mass, balancing the function and cost, and strengthening the antibacterial property and long-term stability. High temperature promotes the diffusion of xylitol molecules, enhancing their reaction activity with isophorone diisocyanate, and at the same time accelerating the evaporation of water, indirectly increasing the solid content of the system. At high rotation speeds, xylitol can inhibit the secondary aggregation of droplets caused by shear force and maintain the particle size uniformity.

[0030] The final product of the production process of the fragrance microcapsule emulsion of the present invention is the fragrance microcapsule emulsion. The composition of the fragrance microcapsule emulsion product by mass percentage is as follows: 10 - 20% core material, 5 - 15% wall material, 50 - 70% continuous phase, 1 - 3% functional auxiliary agent, and the balance is other components; the core material is a fragrance essential oil composition, including: 6 - 12% sandalwood essential oil, 1 - 3% agarwood balsam essential oil, 1 - 3% borneol essential oil, and 0.5 - 1.5% pepper essential oil; the wall material is an isophorone diisocyanate - arabic gum polysaccharide cross - linker, formed by interfacial polymerization of 3 - 10% isophorone diisocyanate and 2 - 5% arabic gum polysaccharide; the continuous phase is an aqueous arabic gum solution, and the proportion of arabic gum in the aqueous arabic gum solution is 2 - 4%, and the polysaccharide component in arabic gum accounts for 75 - 98% and the protein accounts for 2 - 25%; the arabic gum polysaccharide includes D - galactose, L - arabinose, D - glucuronic acid, L - rhamnose, and 4 - O - methyl - D - glucuronic acid with a mass ratio of 30 - 50:20 - 30:10 - 20:10 - 15:1 - 3; the functional auxiliary agent is xylitol, which is used to adjust the system viscosity, synergistically inhibit bacteria, and assist in the cross - linking reaction; the balance is other components, including unreacted isophorone diisocyanate residues (≤0.1%), trace reaction by - products, and volatile components.

[0031] The fragrance microcapsule emulsion prepared by the production process of the present invention uses fragrance essential oils (sandalwood, agarwood balsam, borneol, and pepper essential oils) as the core material, which is encapsulated in a dense polyurethane / polyurea wall material formed by cross - linking of isophorone diisocyanate and arabic gum polysaccharide; the aqueous phase uses an arabic gum solution as the continuous phase, supplemented with xylitol to adjust the viscosity and antibacterial function, forming a homogeneous and stable emulsion system. Among them, the polysaccharide component stabilizes the oil - water interface through hydrogen bonding, electrostatic repulsion, and hydrophobic interactions, and xylitol synergistically with the fragrance essential oil to achieve broad - spectrum antibacterial. The final product has the characteristics of long - term slow - release fragrance, high stability, and antibacterial properties, and is suitable for environmental protection application scenarios such as ecological board coatings.

[0032] The antibacterial effect of the fragrance microcapsule emulsion of the present invention is mainly achieved through the synergy of natural essential oils in the fragrance additive (such as α-santalol in sandalwood essential oil that destroys the integrity of the bacterial cell membrane, and capsaicin in pepper essential oil that inhibits the enzyme activity of molds) and xylitol. α-Santalol dissolves the bacterial lipid layer through hydrophobic interaction, pepper essential oil interferes with the metabolic pathway of molds, and xylitol consumes the energy of microorganisms through non-metabolizable sugar alcohol molecules. The three achieve broad-spectrum antibacterial through physical destruction, metabolic interference, and osmotic pressure regulation. By optimizing the oil-water ratio, polysaccharide components, and process parameters, the present invention delays the fragrance volatilization due to the denseness of the microcapsule wall material, extends the fragrance release period, and realizes long-term slow release; arabic gum polysaccharide and xylitol synergistically stabilize the emulsion to avoid phase separation and achieve high stability; the dual antibacterial mechanism of natural essential oils and xylitol has a combined antibacterial effect and meets the needs of home and public environments; based on natural components (arabic gum, xylitol) and a controllable cross-linking process, it is green and environmentally friendly and meets the standards of ecological materials.

[0033] The present invention includes a homogenizing and dispersing device for the production of microcapsule emulsion. The device includes a dispersion barrel, a feed box, four sets of legs, a feed pipe, a nozzle, a discharge valve, an ultrasonic treatment device, and a dispersion device. The feed box is installed on the front side of the top of the dispersion barrel through four sets of legs. The top of the feed box is connected and provided with a feed pipe. The input end of the feed pipe is connected to the bottom of the feed box. The output end of the feed pipe passes through the top of the dispersion barrel and extends into its interior to be connected to the nozzle. The lower side of the right end of the dispersion barrel is connected and provided with a discharge pipe. The discharge valve is installed on the discharge pipe. The ultrasonic treatment device is installed on the feed pipe. The dispersion device is installed inside the dispersion barrel.

[0034] In the homogenization and dispersion device described in the present invention, in the production process of microcapsule emulsion, the dispersion device built into the device breaks the oil-phase droplets into tiny particles with a size of 1-10 μm through a high-speed shearing force of 4000-10000 rpm, forming a uniformly dispersed emulsion system, ensuring the uniformity of the microcapsule particle size, and enhancing the sustained-release performance and storage stability; the ultrasonic treatment device is installed on the feed pipe, and by utilizing the cavitation effect and mechanical vibration, it pre-disperses the oil-phase droplets during the raw material transportation process, reduces the risk of droplet coalescence, assists the subsequent homogenization step, reduces energy consumption and improves the process efficiency; the feed box evenly sprays the oil phase into the water phase at a rate of 1-3 mL / min through the feed pipe and the nozzle, avoiding local overload or large droplets, ensuring sufficient contact between the oil and water phases, forming a stable emulsion template, and providing a basis for the interfacial polymerization reaction; inside the dispersion tank, the dynamic stability of the emulsion is maintained through the stirring device, preventing the sedimentation or aggregation of microcapsules, and at the same time promoting the cross-linking reaction between isophorone diisocyanate and arabic gum polysaccharide through the heating function, and curing the wall material structure; the discharge valve controls the output of the emulsion, and combined with the overall design of the device, ensures the rapid discharge of the emulsion after the reaction is complete, reduces the residue, and guarantees the consistency between batches. Through the synergistic effect of mechanical dispersion, ultrasonic assistance, precise material control and dynamic reaction control, this device solves the problems of uneven dispersion, wide particle size distribution and low efficiency existing in the traditional process, significantly improves the encapsulation rate, stability and functional performance of the microcapsule emulsion, and at the same time meets the requirements of green production.

[0035] In summary, the present invention has the following beneficial effects: 1. Different from the traditional preparation process, the present invention encapsulates fragrance essential oils (sandalwood, agarwood resin, borneol and pepper essential oils) in a dense wall material formed by the cross-linking of isophorone diisocyanate and arabic gum polysaccharide through microcapsule technology, delaying the volatilization of the essential oils; the microcapsule particle size and cross-linking density regulate the release rate, and the fragrance release period is significantly extended, realizing the gradient release of the "wood-smoky-cool-spicy" four-dimensional fragrance notes. The finished emulsion is compatible with the surface coating of ecological boards, endowing the material with long-lasting fragrance, antibacterial and antioxidant properties; 2. Through the optimization of the composite fragrance formula, the present invention combines the natural essential oil components of sandalwood, agarwood resin, borneol and pepper in a specific proportion. The α-santalol in the sandalwood essential oil destroys the bacterial cell membrane, and the capsaicin in the pepper essential oil inhibits the metabolism of molds. Combined with the enhancement of the antibacterial diffusivity of borneol, a broad-spectrum antibacterial function is achieved. At the same time, in synergistic action with xylitol, a dual antibacterial mechanism is realized through physical destruction, metabolic interference and osmotic pressure regulation; 3. The production process of the fragrance microcapsule emulsion of the present invention realizes efficient homogenization and dynamic crosslinking through an oil phase-aqueous phase emulsification-crosslinking synergistic process and staged parameter control; adopts a high-speed shearing combined with ultrasonic pre-dispersion technology to accurately control the oil droplet size and improve the uniformity of the emulsion; staged temperature control and dynamic stirring ensure that the crosslinking reaction is fully completed, with the residual free isocyanate ≤ 0.1%, and the safety meets the standards; the hydrogen bond network of arabic gum polysaccharide and the viscosity regulation function of xylitol effectively inhibit emulsion stratification and phase separation, and improve storage stability; the used homogenization and dispersion device accurately controls the material through a feed pipe nozzle and ultrasonic pre-dispersion technology, significantly reduces energy consumption and improves dispersion efficiency, and the temperature control and dynamic stirring design in the dispersion barrel combined with the optimization of the discharge valve reduce batch-to-batch differences and improve production efficiency; this device solves the problems of uneven dispersion and wide particle size distribution in the traditional production process and provides reliable support for large-scale industrial production; 4. In the production process of the present invention, the addition of xylitol not only regulates the system viscosity and assists in the crosslinking reaction, but also inhibits microbial metabolism through osmotic pressure, reduces the use of additional bacteriostatic agents, and realizes viscosity regulation, antibacterial synergy and auxiliary crosslinking with "one agent with multiple effects", reducing production costs; 5. Different from traditional microcapsule technology, the present invention adopts an interfacial polymerization reaction of isophorone diisocyanate and arabic gum polysaccharide to form a dense polyurethane / polyurea crosslinking network, improving the core material encapsulation rate, far exceeding the traditional process; by accurately regulating the proportions of polysaccharide components such as D-galactose and L-arabinose in arabic gum, the emulsion system is stabilized by hydrogen bonds, electrostatic repulsion and hydrophobic interactions, improving storage stability; the introduction of L-rhamnose and 4-O-methyl-D-glucuronic acid enhances the hydrophobicity of the wall material, effectively delays the volatilization of the core material, and reduces the interference of environmental temperature and humidity on the aroma release; 6. The green and environmental protection characteristics of the present invention are reflected in the wide application of natural raw materials. Arabic gum, xylitol and natural essential oils replace traditional synthetic emulsifiers and preservatives, avoiding the potential risks of synthetic emulsifiers and meeting the environmental protection standards of ecological boards; the residual amount of isophorone diisocyanate is reduced to below the safety threshold through process optimization, with fewer reaction by-products. At the same time, the combination of xylitol reduces free toxic substances, meeting the home health needs and taking into account functionality and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic structural diagram of the first perspective of the homogenization and dispersion device used in the present invention; Figure 2 is a schematic structural diagram of the second perspective of the homogenization and dispersion device used in the present invention; Figure 3 is Figure 1 an enlarged structural diagram of A in Reference numerals in the drawings: 1, dispersion barrel; 2, material guiding box; 3, feed pipe; 4, support leg; 5, material guiding pipe; 6, spray head; 7, discharge pipe; 8, discharge valve. Detailed implementation mode

[0037] This specific embodiment is only an interpretation of the present invention and does not limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

[0038] Example 1

[0039] S1 Preparation of oil phase: 60% sandalwood essential oil, 15% agarwood resin essential oil, 15% borneol essential oil and 10% pepper essential oil are mixed to obtain a fragrance additive, and then evenly mixed with 2 times the amount of isophorone diisocyanate to obtain a mixed oil phase; S2 Preparation of water phase: Gum arabic is dissolved in 20 times the mass of water and stirred until completely dissolved to prepare a water phase; S3 Emulsification process: The mixed oil phase is slowly added to 4 times the amount of the water phase. After preliminary stirring for 10 minutes, it is homogenized at a speed of 8000 rpm for 10 minutes. The mixed liquid is heated to 50 °C, and an aqueous solution of xylitol with a concentration of 8% and accounting for 10% of the total liquid mass is added under stirring at 800 rpm, and the temperature is raised to 70 °C for a liquefaction reaction for 2 hours to obtain a fragrance microcapsule emulsion.

[0040] The homogenizing and dispersing device used in the present invention includes a dispersion barrel 1, a material guiding box 2, four groups of support legs 4, a material guiding pipe 5, a spray head 6, a discharge valve 8, an ultrasonic treatment device and a dispersing device. The material guiding box 2 is installed on the front side of the top of the dispersion barrel 1 through four groups of support legs 4. The top of the material guiding box 2 is connected and provided with a feed pipe 3. The input end of the material guiding pipe 5 is connected to the bottom end of the material guiding box 2, and the output end of the material guiding pipe 5 passes through the top of the dispersion barrel 1 and extends into its interior to be connected to the spray head 6. The lower side of the right end of the dispersion barrel 1 is connected and provided with a discharge pipe 7, and the discharge valve 8 is installed on the discharge pipe 7. The ultrasonic treatment device is installed on the material guiding pipe 5, and the dispersing device is installed inside the dispersion barrel 1; the microcapsule emulsion is introduced into the interior of the material guiding box 2 through the feed pipe 3, and the microcapsule emulsion is then sprayed into the interior of the dispersion barrel 1 by the spray head 6 through the material guiding pipe 5. When the microcapsule emulsion passes through the material guiding pipe 5, it is ultrasonically dispersed by the ultrasonic treatment device. At the same time, the dispersing device is turned on, and the dispersing device performs secondary dispersion on the microcapsule emulsion. After the microcapsule emulsion is dispersed, the discharge valve 8 is opened, and the microcapsule emulsion is discharged through the discharge pipe 7. By setting this device, not only can the microcapsule emulsion be dispersed by ultrasonic waves, but also the microcapsule emulsion can be secondarily dispersed by the dispersing device, improving its dispersion effect.

[0041] Example 2

[0042] Preparation of oil phase S1: 70% sandalwood essential oil, 10% agarwood resin essential oil, 10% borneol essential oil and 10% pepper essential oil are mixed to obtain a fragrance additive, and then evenly mixed with 1 times the amount of isophorone diisocyanate to obtain a mixed oil phase; Preparation of water phase S2: Dissolve gum arabic in 15 times the mass of water, stir until completely dissolved to prepare a water phase; Emulsification process S3: Slowly add the mixed oil phase to 3 times the amount of the water phase. After initially stirring for 5 minutes, homogenize at a speed of 7000 rpm for 5 minutes. Heat the mixed solution to 40 °C, and add a 2% xylitol aqueous solution accounting for 5% of the total liquid mass while stirring at 300 rpm. Raise the temperature to 60 °C and carry out a liquefaction reaction for 1 hour to obtain a fragrance microcapsule emulsion.

[0043] Example 3

[0044] Preparation of oil phase S1: 50% sandalwood essential oil, 20% agarwood resin essential oil, 20% borneol essential oil and 10% pepper essential oil are mixed to obtain a fragrance additive, and then evenly mixed with 3 times the amount of isophorone diisocyanate to obtain a mixed oil phase; Preparation of water phase S2: Dissolve gum arabic in 25 times the mass of water, stir until completely dissolved to prepare a water phase; Emulsification process S3: Slowly add the mixed oil phase to 5 times the amount of the water phase. After initially stirring for 15 minutes, homogenize at a speed of 10000 rpm for 15 minutes. Heat the mixed solution to 60 °C, and add a 10% xylitol aqueous solution accounting for 15% of the total liquid mass while stirring at 1000 rpm. Raise the temperature to 80 °C and carry out a liquefaction reaction for 3 hours to obtain a fragrance microcapsule emulsion.

[0045] Example 4

[0046] Preparation of oil phase S1: 65% sandalwood essential oil, 15% agarwood resin essential oil, 15% borneol essential oil and 5% pepper essential oil are mixed to obtain a fragrance additive, and then evenly mixed with 1 times the amount of isophorone diisocyanate to obtain a mixed oil phase; The operations of preparation of water phase S2 and emulsification process S3 are the same as those in Example 1 to obtain a fragrance microcapsule emulsion.

[0047] Example 5

[0048] The operations of preparation of oil phase S1 and water phase S2 are the same as those in Example 1; Emulsification process S3: Slowly add the mixed oil phase to 4 times the amount of the water phase. After initially stirring for 15 minutes, homogenize at a speed of 9000 rpm for 10 minutes. Heat the mixed solution to 55 °C, and add a 10% xylitol aqueous solution accounting for 10% of the total liquid mass while stirring at 600 rpm. Raise the temperature to 75 °C and carry out a liquefaction reaction for 3 hours to obtain a fragrance microcapsule emulsion.

[0049] Comparative Example 1 Preparation of S1 oil phase: The same as in Example 1; Preparation of S2 aqueous phase: Replace gum arabic with gelatin, dissolve it in 20 times the mass of water, and stir until completely dissolved to make the aqueous phase; S3 Emulsification process: Slowly add the mixed oil phase to 4 times the amount of the aqueous phase. After preliminary stirring for 10 minutes, homogenize it at a speed of 8000 rpm for 10 minutes. Heat the mixed solution to 50 °C, and add an aqueous solution of xylitol with a concentration of 10% and a total liquid mass of 15% under stirring at 800 rpm. Raise the temperature to 70 °C and carry out a liquefaction reaction for 2 hours to obtain the fragrance microcapsule emulsion.

[0050] Comparative Example 2 Operations for the preparation of S1 oil phase and S2 aqueous phase are the same as in Example 1; S3 Emulsification process: Slowly add the mixed oil phase to 4 times the amount of the aqueous phase. After preliminary stirring for 10 minutes, homogenize it at a speed of 8000 rpm for 10 minutes. Heat the mixed solution to 50 °C, and raise the temperature to 70 °C under stirring at 800 rpm and carry out a liquefaction reaction for 2 hours to obtain the fragrance microcapsule emulsion.

[0051] Comparative Example 3 Preparation of S1 oil phase: Mix 60% sandalwood essential oil, 15% agarwood essential oil, 15% borneol essential oil and 10% pepper essential oil to obtain a fragrance additive as the mixed oil phase; Operation for the preparation of S2 aqueous phase is the same as in Example 1; S3 Emulsification process: Directly add the mixed oil phase to the aqueous phase. After preliminary stirring for 5 minutes, homogenize it at a speed of 3000 rpm for 5 minutes. Heat the mixed solution to 30 °C, and raise the temperature to 50 °C under stirring and carry out a liquefaction reaction for 1 hour to obtain the fragrance emulsion.

[0052] Performance detection Perform aroma performance detection, antibacterial performance detection, physical and mechanical performance detection and safety detection on the fragrance emulsion products prepared in Examples 1-5 and Comparative Examples 1-3 respectively.

[0053] 1. Aroma performance detection 1.1 Aroma release rate Detection method: Use the static headspace method to evaluate the aroma release rate. Place a certain amount of the fragrance microcapsule emulsion sample in a sealed container, place it in a constant temperature water bath, sample at different time intervals, and analyze the content change of the fragrance components in the sample through a gas chromatography-mass spectrometry (GC-MS) instrument to calculate the aroma release rate.

[0054] Evaluation index: Initial release rate: Reflects the aroma release intensity of the fragrance microcapsule emulsion in the initial stage of use, with the unit of mg / (h·g).

[0055] Average release rate: The average aroma release rate during the test period, which is used to evaluate the uniformity of aroma release, with the unit of mg / (h·g).

[0056] Release half-life: The time required for the release amount of the fragrance component to decrease to half of the initial release amount, which is used to measure the persistence of the aroma, with the unit of hour (h).

[0057] 1.2 Aroma persistence Detection method: Invite 10 professional olfactory assessors to regularly sniff and evaluate the aroma of the fragrance microcapsule emulsion sample under the conditions of a temperature of 25°C and a relative humidity of 50%, and record the time from the initial intensity of the aroma to the point where it cannot be perceived.

[0058] Evaluation indicators: Duration: The total time from when the fragrance microcapsule emulsion starts to release the aroma to the point where the aroma cannot be perceived, with the unit of hour (h).

[0059] 1.3 Aroma intensity Detection method: Use the nine-point scale method. Professional olfactory assessors score and evaluate the aroma intensity of the fragrance microcapsule emulsion sample. 1 point indicates no aroma, and 5 points or 9 points indicate a very strong aroma.

[0060] Evaluation indicators: Initial aroma intensity: The aroma intensity of the fragrance microcapsule emulsion just after it is prepared or just after it is applied to the surface of the board, with the unit of point, on a full score scale of 5 points.

[0061] Average aroma intensity: The average aroma intensity during the test period, which is used to evaluate the overall performance of the aroma, with the unit of point, on a full score scale of 5 points.

[0062] 2. Antibacterial performance detection 2.1 Antibacterial property Detection method: Dilute the fragrance microcapsule emulsion sample to different concentrations, take an appropriate amount of the sample and drop it on an agar plate containing bacteria (such as Escherichia coli, Staphylococcus aureus, etc.), observe the formation of the inhibition zone, measure the diameter of the inhibition zone, and record the average value.

[0063] Evaluation indicators: Diameter of the inhibition zone: The unit is millimeter (mm). The larger the diameter, the stronger the antibacterial property of the sample.

[0064] 2.2 Antimildew property Detection method: Coat the fragrance microcapsule emulsion sample on the surface of a specific culture medium, place it in a culture environment containing molds (such as Aspergillus, Penicillium, etc.), regularly observe the growth of the molds, record the growth grade of the molds, and evaluate the antimildew grade according to the growth of the molds.

[0065] Evaluation indicators: Mildew-proof grade: It is divided into grades 0 - 4. Grade 0 indicates no mold growth, and grade 4 indicates severe mold growth. The lower the grade, the better the mildew-proof performance.

[0066] 3. Physical and mechanical property testing 3.1 Emulsion stability Testing method: Place the fragrance microcapsule emulsion sample in a centrifuge tube, centrifuge at a speed of 6000 rpm for 20 minutes, observe the layering of the emulsion, and measure the volume percentage of the supernatant. Place the fragrance microcapsule emulsion sample in a sealed container, store it at 25°C and 50% relative humidity for a certain period of time, regularly observe the appearance changes of the emulsion, and measure the changes in physical properties such as the particle size distribution and viscosity of the emulsion.

[0067] Evaluation indicators: Centrifugal sedimentation rate: The volume percentage of the supernatant, with the unit of %. The lower the sedimentation rate, the better the stability of the emulsion.

[0068] Storage stability: Comprehensively evaluate the long-term storage stability of the emulsion by observing the appearance changes (such as whether there is layering, precipitation, color change, etc.) and physical property changes (such as whether the particle size distribution becomes wider, whether the viscosity increases or decreases significantly, etc.) during the storage process of the emulsion.

[0069] 3.2 Microcapsule particle size distribution Testing method: Use a laser particle size analyzer to calculate the particle size distribution of the microcapsules by measuring the scattered light intensity distribution of the fragrance microcapsule emulsion sample to the laser, and obtain parameters such as the average value, median, and distribution width of the particle size.

[0070] Evaluation indicators: Average particle size: The average value of the microcapsule particle size, with the unit of micrometer (μm). The smaller the particle size, the better the slow-release performance and stability of the microcapsules usually are.

[0071] Particle size distribution width: Reflects the uniformity of the microcapsule particle size distribution, expressed by the distribution width index. The narrower the distribution width, the more uniform the particle size distribution.

[0072] 3.3 Emulsion viscosity Testing method: Use a rotational viscometer to measure the viscosity of the fragrance microcapsule emulsion sample at 25°C, select an appropriate rotor and rotation speed to obtain the apparent viscosity of the emulsion.

[0073] Evaluation indicators: Apparent viscosity: With the unit of Pascal·second (Pa·s), a moderate viscosity is beneficial to the coating and construction of the emulsion. Excessive or too low viscosity will affect the use performance of the emulsion.

[0074] 4. Safety testing Detection method: Using a high-performance liquid chromatograph, a certain amount of the fragrance microcapsule emulsion sample is dissolved in an appropriate solvent. After pretreatment steps such as filtration and dilution, a solution suitable for injection analysis is prepared. Through separation by a specific chromatographic column and detection by a detector, quantitative analysis of the unreacted IPDI (isophorone diisocyanate) in the fragrance microcapsule emulsion sample is carried out, and the content of the unreacted IPDI in the sample is calculated according to the standard curve method.

[0075] Evaluation indicators: Residual amount of unreacted IPDI: Expressed as a mass percentage (%), it is used to evaluate the content of unreacted IPDI in the fragrance microcapsule emulsion. The safety standard for the residual amount of unreacted IPDI is ≤0.1%, ensuring that it is within a safe range and avoiding potential hazards to humans and the environment.

[0076] 4. Detection results Table 1 Summary of the detection results of the performance of each group of fragrance emulsion products

[0077] 4.1 Detection of aroma performance For the fragrance microcapsule emulsion products of Examples 1 - 5, the initial release rate of the aroma is between 1.0 - 1.5 mg / (h·g), indicating that the fragrance microcapsule emulsion can provide a relatively mild and stable aroma release in the initial stage of use. Among them, the initial release rate of Example 3 is the lowest, indicating that its aroma release is relatively slow and the sustained-release performance is better. Among the fragrance emulsion products of Comparative Examples 1 - 3, the initial release rate of Comparative Example 1 is the highest, indicating that its aroma release is too fast, but it will lead to insufficient aroma persistence. The initial release rate of Comparative Example 3 is also relatively high, indicating that its aroma release is rapid, but it is also difficult to be persistent.

[0078] The average release rate of Examples 1 - 5 is between 0.5 - 0.8 mg / (h·g), indicating that the fragrance microcapsule emulsion can release the aroma evenly during the test period and has good sustained-release performance. Among Comparative Examples 1 - 3, the average release rates of Comparative Example 1 and Comparative Example 2 are relatively high, 1.5 mg / (h·g) and 1.2 mg / (h·g) respectively, indicating that their aroma releases are uneven and the release rates are relatively fast, making it difficult to achieve long-term sustained release.

[0079] The release half-life of Examples 1 - 5 is between 36 - 60 hours, indicating that the fragrance microcapsule emulsion has good aroma persistence and can maintain the aroma release for a long time. Among them, the release half-life of Example 3 is the longest, indicating that its sustained-release performance is the best. Among Comparative Examples 1 - 3, the release half-lives of Comparative Example 1 and Comparative Example 2 are relatively short, 18 hours and 24 hours respectively, indicating that their aroma release cycles are short and it is difficult to meet the requirements of long-term sustained release.

[0080] The durations of Examples 1-5 are between 96 and 144 hours, indicating that the fragrance of the fragrance microcapsule emulsion can last for a long time. Among them, the duration of Example 3 is the longest, indicating that its fragrance persistence is the best. Among Comparative Examples 1-3, the durations of Comparative Example 1 and Comparative Example 2 are shorter, being 48 hours and 72 hours respectively, indicating that their fragrance persistence is poor.

[0081] The initial fragrance intensities of Examples 1-5 are between 3.5 and 4.8 points, indicating that the fragrance microcapsule emulsion can provide a strong fragrance at the initial stage of use. The initial fragrance intensity of Example 3 is the highest, indicating that its fragrance intensity is relatively high. Among Comparative Examples 1-3, the initial fragrance intensities of Comparative Example 1 and Comparative Example 2 are relatively low, being 3.0 points and 3.5 points respectively, indicating that their fragrance intensities are insufficient.

[0082] The average fragrance intensities of Examples 1-5 are between 3.2 and 4.0 points, indicating that the fragrance microcapsule emulsion can maintain a relatively stable fragrance intensity during the test period. The average fragrance intensity of Example 3 is the highest, indicating that its fragrance intensity is relatively persistent. Among Comparative Examples 1-3, the average fragrance intensities of Comparative Example 1 and Comparative Example 2 are relatively low, being 1.5 points and 2.0 points respectively, indicating that their fragrance intensities are difficult to maintain and the release is uneven.

[0083] Generally speaking, due to the reasonable crosslinking density (crosslinking of isophorone diisocyanate and gum arabic) in the examples, the microcapsule wall material is dense, the initial release rate is low, the release half-life is as long as 36–60 hours, and the fragrance persistence time is 96–144 hours; the initial fragrance intensity is relatively high, and the average intensity is stable, indicating that the fragrance slow-release effect is significant. In Comparative Example 1, gelatin was used to replace gum arabic, resulting in a high initial release rate due to insufficient crosslinking, and the half-life was only 18 hours, with a significant decrease in fragrance intensity. In Comparative Example 2, the emulsion stability without xylitol was poor, the fragrance release was uneven, and the average fragrance intensity was only 2.0 points. In Comparative Example 3, there was no crosslinking agent, no microcapsules were formed, and the fragrance volatilized rapidly, with extremely poor persistence.

[0084] 4.2 Antibacterial Performance Detection The diameters of the antibacterial zones of Examples 1-5 are between 15 and 20 mm, indicating that the fragrance microcapsule emulsion has strong antibacterial properties. The diameter of the antibacterial zone of Example 3 is the largest, indicating that its antibacterial performance is the best. Among Comparative Examples 1-3, the diameters of the antibacterial zones of Comparative Example 1 and Comparative Example 2 are relatively small, being 8 mm and 10 mm respectively, indicating that their antibacterial properties are weak.

[0085] The mildew-proof grades of Examples 1-5 are between 0 and 1 level, indicating that the fragrance microcapsule emulsion has good mildew-proof properties. The mildew-proof grades of Examples 1, 3 and 5 are 0 level, indicating that their mildew-proof properties are the best. Among Comparative Examples 1-3, the mildew-proof grades of Comparative Example 1, Comparative Example 2 and Comparative Example 3 are 3 level, 2 level and 4 level respectively, indicating that their mildew-proof properties are all poor.

[0086] Overall, in the examples, through the synergistic effect of natural essential oils (sandalwood, pepper) and xylitol, the diameter of the antibacterial zone reached 15–20 mm, and the mildew-proof grade was 0–1 level, indicating a broad-spectrum antibacterial effect. In Comparative Example 1, gelatin lacked polysaccharide cross-linking, and the antibacterial zone was only 8 mm, with a mildew-proof grade of 3; in Comparative Example 3, there was no cross-linking agent and the essential oil was not encapsulated, resulting in the worst antibacterial effect.

[0087] 4.3 Physical and mechanical property testing The centrifugal sedimentation rates of Examples 1-5 were between 1% and 5%, indicating good stability of the fragrance microcapsule emulsion. The centrifugal sedimentation rate of Example 3 was the lowest, indicating the best stability. Among Comparative Examples 1-3, the centrifugal sedimentation rates of Comparative Example 1, Comparative Example 2, and Comparative Example 3 were 20%, 15%, and 35% respectively, indicating poor stability.

[0088] The storage stabilities of Examples 1-5 were all good or excellent, indicating that the fragrance microcapsule emulsion could remain stable during long-term storage. The storage stabilities of Example 3 and Example 5 were excellent, indicating the best long-term stability. Among Comparative Examples 1-3, the storage stabilities of Comparative Example 1, Comparative Example 2, and Comparative Example 3 were all poor, being poor, medium, and extremely poor respectively, indicating that they were prone to phenomena such as delamination and precipitation during long-term storage.

[0089] The average particle sizes of Examples 1-5 were between 2.8 and 5.0 μm, indicating a relatively uniform particle size distribution of the fragrance microcapsule emulsion, with smaller microcapsule particle sizes and better slow-release performance. The average particle size of Example 3 was the smallest, indicating the best slow-release performance. Among Comparative Examples 1-3, the average particle sizes of Comparative Example 1 and Comparative Example 2 were larger, being 12.0 μm and 8.5 μm respectively, indicating non-uniform particle size distribution and poor slow-release performance.

[0090] The particle size distribution widths of Examples 1-5 were between 0.6 and 1.2 μm, indicating a relatively uniform particle size distribution of the fragrance microcapsule emulsion. The particle size distribution width of Example 3 was the smallest, indicating the most uniform particle size distribution. Among Comparative Examples 1-3, the particle size distribution widths of Comparative Example 1 and Comparative Example 2 were larger, being 4.5 μm and 3.0 μm respectively, and Comparative Example 3 was unevenly dispersed, all indicating non-uniform particle size distribution and poor dispersibility.

[0091] The apparent viscosities of Examples 1-5 were between 0.4 and 0.6 Pa·s, indicating moderate viscosity of the fragrance microcapsule emulsion, which was suitable for coating and construction. The apparent viscosity of Example 3 was 0.6 Pa·s, indicating moderate viscosity and good stability. Among Comparative Examples 1-3, the apparent viscosity of Comparative Example 1 was higher, indicating too high viscosity, which would affect the construction performance; the apparent viscosity of Comparative Example 3 was lower, indicating too low viscosity, which would also affect the stability of the emulsion.

[0092] Overall, the centrifugal sedimentation rate of the examples is low, the storage stability is excellent, the particle size is uniform, and the viscosity is moderate. In Comparative Example 1, the sedimentation rate is large, the particle size is coarse, and the viscosity is too high. In Comparative Example 3, microcapsules were not formed, the emulsion was severely stratified, and the particle size could not be detected.

[0093] 4.4 Safety Detection The residual amount of unreacted IPDI in Examples 1-5 is between 0.02% and 0.05%, all lower than 0.1%, meeting the safety standards, indicating that the production process of the fragrance microcapsule emulsion can effectively control the residual amount of unreacted IPDI and ensure the safety of the product. During the production process of the fragrance microcapsule emulsion in the examples, the cross-linking reaction is sufficient. The interfacial polymerization reaction between isophorone diisocyanate (IPDI) and arabic gum polysaccharide has a high degree of completion under high temperature, homogenization, and the assistance of xylitol; the residual groups are effectively consumed; the hydroxyl groups of xylitol combine with the unreacted IPDI isocyanate groups (-NCO) to reduce free toxic substances; the process parameters are optimized by stage temperature control and dynamic stirring to ensure complete reaction. In Comparative Examples 1-3, the residual amounts of unreacted IPDI in Comparative Example 1 and Comparative Example 2 are relatively high, 1.2% and 0.8% respectively. In Comparative Example 1, gelatin lacks polysaccharide components (such as D-galactose, L-arabinose) and cannot effectively cross-link with IPDI, resulting in incomplete reaction. At the same time, a dense polyurethane / polyurea wall material is not formed, and the residual IPDI cannot be consumed, resulting in a residual amount as high as 1.2%. Its production process has deficiencies in controlling the residual amount of unreacted IPDI, posing potential hazards to the environment and human health. In Comparative Example 2, the hydroxyl groups of xylitol are missing, unable to assist the cross-linking reaction and combine with the residual IPDI; the emulsion stability is poor, and the viscosity and osmotic pressure are not adjusted, resulting in a reduced reaction efficiency. In Comparative Example 3, no cross-linking agent is used, and IPDI is not introduced into the system, so there is no residue. However, it does not form a microcapsule structure, the fragrance volatilizes rapidly, the emulsion is severely stratified, and its practical application value is low.

[0094] Embodiments of the present invention achieve long-acting fragrance release, broad-spectrum antibacterial, high stability and safety through the interfacial crosslinking of isophorone diisocyanate and gum arabic and the synergistic effect of xylitol. Replacing key components, lacking crosslinking agents or xylitol in the comparative examples all lead to a significant decrease in performance, verifying the necessity of the process design. Among them, the crosslinking density determines the compactness of the microcapsule wall and the release rate. For example, the high crosslinking density in Example 3 corresponds to the longest half-life; xylitol regulates viscosity and inhibits the growth of microorganisms, and the lack of xylitol in Comparative Example 2 results in poor stability; the homogenization speed affects the particle size distribution. The 8000 rpm in Example 1 corresponds to a particle size of 3.5 μm, which is better than the 12 μm in Comparative Example 1. From the analysis of the above data results, it can be seen that Examples 1-5 all show excellent performance in terms of fragrance slow release, antibacterial performance, physical and mechanical properties and safety, and all indicators are better than those of the comparative examples, indicating that the production process of the fragrance microcapsule emulsion of the present invention can effectively improve the comprehensive performance of the product and meet the actual application requirements.

Claims

1. A production process of a fragrance microcapsule emulsion, characterized in that, Specifically, it includes the following steps: S1 Oil phase preparation: Each fragrance essential oil is mixed evenly in proportion to form the main component of the fragrance additive, and then it is mixed evenly again with isophorone diisocyanate in a ratio of 1:1 - 3:1 to obtain a mixed oil phase; S2 Water phase preparation: Gum arabic is dissolved in 15 - 25 times its mass of water and stirred until completely dissolved to prepare the water phase; S3 Emulsification process: The mixed oil phase is slowly added to the water phase. After preliminary stirring, it is homogenized at a speed of 4000 - 10000 rpm for 5 - 15 minutes. Then the mixed solution is added to the xylitol aqueous solution, heated and stirred for 1 - 3 hours for the liquefaction reaction to form the fragrance microcapsule emulsion.

2. The production process of the fragrance microcapsule emulsion according to claim 1, characterized in that, The oil phase includes isophorone diisocyanate and a fragrance additive with a mass ratio of 1:1 - 3. The composition of the fragrance additive by mass percentage includes: 50 - 70% sandalwood essential oil, 10 - 20% agarwood resin essential oil, 10 - 20% borneol essential oil, and 5 - 10% pepper fragrance essential oil.

3. The production process of the fragrance microcapsule emulsion according to claim 1, characterized in that, The water phase includes gum arabic and water with a mass ratio of 1:15 - 25. The gum arabic includes protein and polysaccharide with a mass ratio of 2 - 25:75 - 98. The polysaccharide component includes D - galactose, L - arabinose, D - glucuronic acid, L - rhamnose, and 4 - O - methyl - D - glucuronic acid with a mass ratio of 30 - 50:20 - 30:10 - 20:10 - 15:1 - 3.

4. The production process of the fragrance microcapsule emulsion according to claim 1, characterized in that, The mass ratio of the oil phase to the water phase is 1:3 - 5.

5. The production process of the fragrance microcapsule emulsion according to claim 1, wherein, The emulsification process specifically includes the following steps: S3.1 Oil - water phase mixing: The mixed oil phase is added to the water phase at a rate of 1 - 3 mL / min and stirred preliminarily for 5 - 15 minutes to make the oil and water mix evenly; S3.2 Homogenized dispersion: The solution is homogenized at a speed of 4000 - 10000 rpm for 5 - 15 minutes to ensure the uniform dispersion of the essence and the encapsulating material; S3.3 Liquefaction reaction: The mixed solution is heated to 40 - 60 °C, and the xylitol aqueous solution is added under stirring at 300 - 1000 rpm, and then heated to 60 - 80 °C for reaction for 1 - 3 hours to form the fragrance microcapsule emulsion.

6. The production process of the fragrance microcapsule emulsion according to claim 5, characterized in that, The mass concentration of the xylitol aqueous solution is 2 - 10%, and the addition amount of the xylitol aqueous solution is 5 - 15% of the total liquid mass.

7. The production process of the fragrance microcapsule emulsion according to claim 1, characterized in that The finished product of the prepared fragrance microcapsule emulsion is composed of the following components by mass percentage: 10-20% core material, 5-15% wall material, 50-70% continuous phase, 1-3% functional auxiliary agent, and the balance is other components; the core material is a fragrance essential oil composition, including: 6-12% sandalwood essential oil, 1-3% agarwood resin essential oil, 1-3% borneol essential oil and 0.5-1.5% pepper essential oil; the wall material is an isophorone diisocyanate-arabic gum polysaccharide crosslinking product, formed by interfacial polymerization of 3-10% isophorone diisocyanate and 2-5% arabic gum polysaccharide; the continuous phase is an aqueous arabic gum solution, in which arabic gum accounts for 2-4%, and the polysaccharide component in arabic gum accounts for 75-98% and the protein accounts for 2-25%; the arabic gum polysaccharide includes D-galactose, L-arabinose, D-glucuronic acid, L-rhamnose and 4-O-methyl-D-glucuronic acid with a mass ratio of 30-50:20-30:10-20:10-15:1-3; the functional auxiliary agent is xylitol, which is used to adjust the system viscosity, synergistically inhibit bacteria and assist the crosslinking reaction; the balance is other components, including unreacted isophorone diisocyanate residues (≤0.1%), trace reaction by-products and volatile components.

8. The production process of the fragrance microcapsule emulsion according to claim 1, characterized in that, It includes a homogenizing and dispersing device for the production of microcapsule emulsion. The device includes a dispersion barrel (1), a feed box (2), four sets of legs (4), a feed pipe (5), a spray head (6), a discharge valve (8), an ultrasonic treatment device and a dispersion device. The feed box (2) is installed on the front side of the top of the dispersion barrel (1) through four sets of legs (4). The top of the feed box (2) is connected with a feed pipe (3) in a communicating way. The input end of the feed pipe (5) is communicated with the bottom end of the feed box (2). The output end of the feed pipe (5) passes through the top of the dispersion barrel (1) and extends into its interior to be connected with the spray head (6). The lower side of the right end of the dispersion barrel (1) is communicated with a discharge pipe (7). The discharge valve (8) is installed on the discharge pipe (7). The ultrasonic treatment device is installed on the feed pipe (5), and the dispersion device is installed inside the dispersion barrel (1).

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