Microcapsule emulsion based on natural plant material and method for its preparation

Abstract

The application relates to the technical field of microcapsules, and particularly discloses a microcapsule emulsion based on natural plant materials and a preparation method thereof. The preparation method comprises the following steps: S1, mixing modified gum arabic and deionized water, adding luffa sponge powder after the modified gum arabic is dissolved, and uniformly stirring to obtain a main emulsifier; S2, adding an amino resin crosslinking agent into the main emulsifier, and uniformly stirring to obtain a mixed solution; S3, adding essence into the mixed solution, and emulsifying at 15000 rpm for 3 minutes to obtain an emulsion; S4, adjusting the pH of the emulsion to 4.0, increasing the temperature to 60 DEG C at a rate of 2 DEG C per minute, stirring for 2 hours, and maintaining the pH at 3.5-4.5; S5, increasing the temperature to 70 DEG C, stirring for 2 hours at constant temperature, adjusting the pH to 7.5, and naturally cooling to room temperature to obtain the microcapsule emulsion. The microcapsule emulsion has the advantages of uniform particle size distribution, good stability and the ability of removing peculiar smell.

Description

Technical Field

[0001] This invention relates to the field of microcapsule technology, and in particular to a microcapsule emulsion based on natural plant materials and its preparation method. Background Technology

[0002] To impart a lasting fragrance to cotton fabrics, the method of adding fragrances using textile conditioners as carriers during washing or tumble drying has been used for many years. However, this method suffers from a very short fragrance retention time; the fragrance typically disappears after just one wash. To overcome this problem, a fragrance microcapsule emulsion technology has now been developed. Fragrance microcapsule emulsions use microcapsule technology to encapsulate fragrance within the capsule wall, creating a fragrance microcapsule finishing agent. When applied in finishing processes, the physical barrier effect of the capsule wall reduces fragrance evaporation, achieving a slow-release effect and significantly extending the fragrance retention time on cotton fabrics.

[0003] Currently, most commercially available aroma microcapsules are single-fragrance microcapsules, and their capsule wall materials are generally natural polymers such as modified starch, gelatin, or gum arabic. Although these materials have a certain encapsulation capacity, they have inherent defects: on the one hand, the capsule wall density is poor, and the membrane structure has micropores, which not only leads to uneven release of the fragrance core and insufficient sustained release, but also easily causes premature loss of fragrance due to leakage of the capsule wall, affecting the stability of the aroma effect; on the other hand, these capsule wall materials lack natural affinity with cotton fibers and cannot be directly and firmly bonded to the fibers. They require the addition of cross-linking agents or fixing agents to assist in fixation, which not only increases the complexity of the process and production costs, but some auxiliaries may also have a negative impact on the softness and breathability of cotton fabrics. Meanwhile, fragrances themselves are volatile and have poor heat resistance, making them prone to thermal decomposition during subsequent high-temperature baking and finishing processes, further depleting the effective components. Furthermore, the stability of existing aromatic microcapsule emulsions is generally poor, manifesting as stratification, flocculation, and even demulsification during storage. Stability is particularly difficult to control under temperature fluctuations, changes in mechanical stirring intensity, and when compounded with other finishing auxiliaries. This is mainly due to an imbalance in the hydrophilicity and hydrophobicity of the capsule wall material, and improper selection and ratio of emulsifiers, resulting in the inability to form a stable dispersion system between the oil phase (fragrance) and the aqueous phase. In addition, the emulsion particle size distribution is severely insufficient, with a large and highly dispersed particle size range. Some microcapsules with excessively large particle sizes can cause rough fabric surfaces and a stiff feel, while those with excessively small particle sizes are prone to permeation loss or premature rupture, releasing fragrance. This affects the uniformity of fragrance distribution in the finished fabric and leads to significant differences in the sustained-release rates of microcapsules with different particle sizes, failing to achieve a long-lasting and stable fragrance effect and failing to meet the demand for long-lasting and stable fragrance finishing in high-end cotton fabrics.

[0004] Regarding the aforementioned technologies, the inventors believe that it is necessary to develop a microcapsule emulsion that can both improve emulsion stability and remove odors. Summary of the Invention

[0005] To address the technical deficiencies of existing technologies, this application provides a microcapsule emulsion based on natural plant materials and its preparation method. In a first aspect, this application provides a method for preparing a microcapsule emulsion based on natural plant materials, using the following technical solution: A method for preparing a microcapsule emulsion based on natural plant materials includes the following steps: S1: Mix modified gum arabic with deionized water, and after the modified gum arabic is dissolved, add loofah powder and stir evenly to obtain the main emulsifier; S2: Add amino resin crosslinking agent to the main emulsifier and stir until uniform to obtain a mixture; S3: Add fragrance to the mixture and emulsify at 15000 rpm for 3 minutes to obtain an emulsion; S4: Adjust the pH of the emulsion to 4.0, heat to 60°C at a rate of 2°C / min, stir for 2 hours and maintain the pH between 3.5 and 4.5; S5: Heat to 70℃, stir at a constant temperature for 2 hours to solidify, adjust pH to 7.5, and cool naturally to room temperature to obtain microcapsule emulsion.

[0006] By employing the above technical solutions, modified gum arabic can form a stable adsorption layer at the oil-water interface, reducing interfacial tension and improving the stability of the emulsion system. Loofah powder, as a natural plant filler, can also act as a Pickering emulsifier. The principle is that loofah powder, as solid particles, can irreversibly adsorb at the oil-water interface, forming a physical barrier that hinders the collision and fusion of oil droplets. Compared to traditional surfactant emulsification, this solid-particle-stabilized emulsion system has stronger anti-agglomeration ability. Simultaneously, its porous structure can serve as nucleation sites during the emulsification process, further inhibiting oil droplet aggregation and forming a synergistic effect with the amino resin crosslinking agent to construct a structurally complete microcapsule wall material. Subsequent precise temperature and pH control during polymerization and curing steps ensures that the crosslinking reaction proceeds fully and orderly, reducing wall material defects and thus improving the encapsulation effect and structural stability of the microcapsules for fragrances, giving the emulsion both good dispersibility and core material retention.

[0007] Preferably, the modified gum arabic in step S1 is prepared by the following method: Step 1: Mix gum arabic with deionized water, dissolve, and then cool for later use; Step 2: Mix octenyl succinic anhydride, Tween 80 and deionized water, and emulsify. Step 3: Add the solution obtained in step S2 dropwise to the gum arabic solution obtained in step S1 to carry out the grafting reaction, and adjust the pH during the reaction; Step 4: Adjust the pH to terminate the reaction; Step 5: The liquid after the reaction is terminated is concentrated, spray-dried and sieved in sequence to obtain modified gum arabic.

[0008] By employing the above technical solution, octenyl succinic anhydride (OSA), as a hydrophobic modifier, can introduce hydrophobic groups into the gum arabic molecular chain through a grafting reaction, enhancing its affinity for oil-phase fragrances and interfacial adsorption capacity, thus solving the problem of insufficient emulsification stability of unmodified gum arabic. Tween80 effectively prevents OSA from agglomerating during emulsification, ensuring the uniformity of the grafting reaction and making the emulsification performance and dispersibility of the modified gum arabic more stable. Subsequent concentration, spray drying, and sieving processes remove impurities and excess moisture from the system, obtaining a solid powder with uniform particle size. This facilitates the preparation of the main emulsifier and precise control of the component ratio, providing a fundamental guarantee for the stability of the microcapsule emulsion performance.

[0009] Preferably, in step S2, 1 / 3 of the amount of amino resin crosslinking agent is added to the main emulsifier, and the remaining amino resin crosslinking agent is added to the emulsion before adjusting the pH of the emulsion with a pH adjuster in step S4.

[0010] By adopting the above technical solution, the amino resin crosslinking agent can be added in stages, avoiding excessive aggregation of local crosslinking reactions caused by adding it all at once. The first 1 / 3 of the crosslinking agent added can form a preliminary crosslinking network with modified gum arabic and loofah powder, improving the load-bearing capacity of the emulsion system and preventing oil droplet fusion during emulsification; the remaining crosslinking agent added later can further improve the crosslinking structure of the wall material after the emulsion is formed, making the crosslinking reaction more complete and uniform. This step-by-step control method can synergistically improve the compactness of the microcapsule wall material, reduce the leakage channels of the core material, and optimize the particle size distribution, avoiding the problem of excessively large particle size caused by local agglomeration.

[0011] Preferably, step S4 involves stirring at a constant temperature of 40°C, adjusting the pH to 5.0, and maintaining this temperature for 15 minutes; then increasing the temperature to 60°C at a rate of 1°C / minute, adjusting the pH to 4.0, and stirring at this constant temperature and pH for 2 hours.

[0012] By employing the above technical solution, a polymerization reaction system with pH and temperature gradient control was constructed to adapt to the reactivity characteristics of the amino resin crosslinking agent. Pre-reaction at 40℃ and pH 5.0 slows down the initial crosslinking reaction rate, allowing the crosslinking agent to gradually combine with the modified gum arabic molecular chains, avoiding excessively rapid reaction that could lead to rough wall material and increased porosity. A slow heating rate of 1℃ / min and subsequent pH adjustment to 4.0 ensure the orderly progress of the crosslinking reaction, promoting gradual densification of the wall material. This gradient process can synergistically optimize the morphological regularity and particle size uniformity of microcapsules, improve the integrity of the wall material's encapsulation of the core material, and thus enhance the thermal and storage stability of the emulsion.

[0013] Preferably, the loofah powder is pretreated with sodium hydroxide alkaline etching.

[0014] By employing the above technical solution, sodium hydroxide alkaline etching can remove impurities and pectin-like substances adhering to the surface of loofah powder, while simultaneously etching its fibrous structure, increasing the specific surface area and the number of porous structures, and enhancing the binding sites between loofah powder and modified gum arabic and crosslinking agents. The pretreated loofah powder exhibits significantly improved dispersibility, allowing for more uniform distribution within the emulsion system. It acts as a crystal nucleus to more effectively inhibit oil droplet aggregation, while simultaneously forming a tighter bond with the wall material, enhancing the mechanical strength and structural stability of the microcapsule wall material, and synergistically improving the particle size distribution and anti-aging ability of the emulsion.

[0015] Preferably, the mass ratio of the modified gum arabic, deionized water, loofah powder, amino resin crosslinking agent and fragrance is 1: (56.25~62.5): (0.0875~0.25): (6.7~8.3): (37.5~42).

[0016] By adopting the above technical solution, the compatibility of the component ratios is optimized, forming a synergistic system. The ratio of modified gum arabic to deionized water ensures that the main emulsifier has a suitable viscosity, which not only satisfies the stability of the emulsification process but also facilitates the mixing of subsequent components.

[0017] Preferably, the amino resin crosslinking agent is CYMEL385 amino resin.

[0018] By adopting the above technical solution, CYMEL385 amino resin exhibits suitable reactivity, enabling it to undergo cross-linking reactions with the hydroxyl and carboxyl groups of modified gum arabic molecular chains under acidic conditions. This results in a dense wall material structure with a certain degree of flexibility, and the high-temperature resistance and impermeability of its cross-linked products are superior to those of gelatin and other cross-linking agents. Furthermore, CYMEL385 demonstrates good compatibility with modified gum arabic and loofah powder, synergistically enhancing the structural stability of the wall material, reducing core material leakage during thermal storage, and ensuring the long-term performance of the microcapsule emulsion.

[0019] Secondly, this application also provides a microcapsule emulsion based on natural plant materials, employing the following technical solution: A microcapsule emulsion based on natural plant materials is prepared by the above-described method.

[0020] By adopting the above technical solution, this microcapsule emulsion inherits the advantages of synergistic effects and process optimization of the components in the aforementioned preparation methods. Its wall material is formed by cross-linking modified gum arabic, loofah powder, and CYMEL385 amino resin, combining the compatibility of natural plant materials with the stability of synthetic cross-linked structures. The emulsion features high encapsulation efficiency, uniform particle size distribution, and good thermal and storage stability. Furthermore, its core components are all natural plant materials or highly compatible cross-linking agents, free of additional harmful impurities, making it suitable for diverse applications such as fragrance carriers. Simultaneously, it solves the technical problems of low encapsulation efficiency, insufficient stability, and uneven particle size in traditional microcapsule emulsions.

[0021] In summary, this application has the following beneficial effects: 1. This application constructs a highly efficient and stable composite wall material system through the synergistic formulation of OSA-modified gum arabic, loofah powder (Pickerling emulsifier), and CYMEL385 amino resin. In principle, modified gum arabic reduces the interfacial tension between oil and water, while loofah powder, as solid particles, adsorbs at the interface to form a physical barrier (Pickerling emulsification) and acts as a nucleus to inhibit oil droplet aggregation. Both react with the amino resin to form a dense wall material. The three components synergistically compensate for the insufficient emulsification or cross-linking capabilities of any single component. Based on the experimental data, the encapsulation rates of Examples 2-7 all reached 91%-95%, which is much higher than that of Comparative Example 1 (76%) and Comparative Example 2 (73%), which did not add loofah powder and used gelatin instead of amino resin. The thermal stability retention rate at 60℃ reached 90%-94%, and the encapsulation rate remained at 90%-93% after 30 days of storage at 25℃, which is significantly better than the comparative examples (thermal stability retention rate of 70%-79%, encapsulation rate after storage of 66%-75%), fully demonstrating the synergistic effect of the components on improving the encapsulation effect and anti-aging ability.

[0022] 2. This application optimizes the process through stepwise addition of crosslinking agents, pH-temperature gradient polymerization, and alkaline etching pretreatment of loofah powder, achieving a highly efficient synergy with the component performance. In principle, stepwise addition of the crosslinking agent avoids excessive local crosslinking and aggregation, the gradient process ensures the orderly advancement of the crosslinking reaction, and the alkaline etching pretreatment improves the dispersibility and binding sites of the loofah powder, collectively improving the emulsion dispersibility and wall material density. Experimental data show that Example 6, using the pH gradient polymerization process, achieved a span value as low as 2.568 and a D(4,3) of 11.254 μm. Example 7, after alkaline etching treatment with loofah powder, had a D(3,2) of only 4.285 μm, both superior to Comparative Example 3 (span value 2.986, D(4,3) 15.328 μm) and other comparative examples. This demonstrates that the synergistic effect of the process and components can effectively refine the particle size and narrow the distribution, while enhancing the structural stability of the wall material, solving the performance degradation problems caused by uneven particle size and structural defects in traditional processes. Detailed Implementation

[0023] The present application will be further described in detail below with reference to the embodiments.

[0024] The raw materials used in this specific implementation method, example, and comparative example are all conventional commercially available products.

[0025] Example 1 A modified gum arabic is prepared by the following method: S1: Preparation of gum arabic aqueous solution Weigh 100g of gum arabic and add 900g of deionized water to a constant temperature water bath with a stirrer. Heat to 60℃ and stir at 300rpm for 30 minutes until completely dissolved, to obtain a 10wt% clear and homogeneous solution. Allow it to cool naturally to 23℃ and maintain the temperature.

[0026] S2: Preparation of OSA emulsion Weigh 3g of octenyl succinic anhydride (OSA) and 0.15g of Tween80, add 20g of deionized water, and emulsify at 10,000 rpm for 2 minutes using a high-speed shear emulsifier to prevent OSA from agglomerating.

[0027] S3: Grafting reaction Adjust the pH of solution 1 to 8.5 using a 10wt% sodium hydroxide solution, maintain the temperature at 23℃, and then add emulsion 2 dropwise at a rate of 1 mL / min. After the addition is complete, stir at 300 rpm for 1.56 hours. Measure the pH every 30 minutes, and if it deviates from 8.5, finely adjust it with a small amount of sodium hydroxide solution.

[0028] S4: Reaction terminated Adjust the pH of the reaction solution to 6.2 with 10wt% citric acid solution, stir for 10 minutes, terminate the reaction and neutralize the alkali solution.

[0029] S5: Post-processing The terminated reaction solution was transferred to a vacuum concentrator and concentrated at 45°C and -0.085 MPa to a solid content of 30 wt%. Then, it was dried using a spray dryer with an inlet air temperature of 180°C, an outlet air temperature of 80°C, and a feed rate of 5 mL / min to obtain a white powder. This powder was then sieved through an 80-mesh sieve to obtain modified gum arabic.

[0030] Example 2 A microcapsule emulsion based on natural plant materials includes: 4.8g of modified gum arabic (Example 1), 270g of deionized water, 0.42g of loofah powder, 32.5g of CYMEL385 amino resin, and 180g of fragrance.

[0031] The microcapsule emulsion in this embodiment was prepared by the following method: Preparation steps: S1: Preparation of Primary Emulsifier Weigh 4.8g of modified gum arabic, add 270g of deionized water, place in a 60℃ constant temperature water bath, and stir magnetically for 30 minutes until completely dissolved to form a transparent and homogeneous solution; then add 0.42g of loofah powder and continue stirring for 15 minutes to evenly disperse the loofah powder in the solution to obtain the main emulsifier.

[0032] S2: Crosslinking agent added Cool the main emulsifier naturally to 40°C, add 32.5g of CYMEL385 amino resin, and stir at low speed for 10 minutes to ensure that the crosslinking agent is completely dissolved and fully mixed with the main emulsifier.

[0033] S3: Emulsification treatment Slowly add 180g of flavoring to the above mixture, start the high-speed emulsifier, and emulsify for 3 minutes at 15000rpm to form a stable emulsion.

[0034] S4: Polymerization reaction The emulsion was transferred to a top-mounted stirred reactor and stirred at a constant temperature of 40°C. The pH of the system was adjusted to 4.0 with a 10wt% citric acid aqueous solution. The temperature was then increased to 60°C at a rate of 2°C / min and stirred continuously at this temperature for 2 hours. The pH was monitored in real time and maintained within the range of 3.5-4.5.

[0035] S5 Curing and Post-treatment The system temperature was raised to 70℃ and stirred at a constant temperature for 2 hours to complete the curing reaction. After the reaction was completed, the pH value of the system was adjusted to 7.5 with 10wt% sodium hydroxide aqueous solution and allowed to cool naturally to room temperature to obtain the target microcapsule emulsion.

[0036] Example 3 A microcapsule emulsion based on natural plant materials comprises: 4.8g of modified gum arabic (Example 1), 280g of deionized water, 0.8g of loofah powder, 36g of CYMEL385 amino resin, and 190g of fragrance.

[0037] The preparation method in this embodiment is the same as that in Example 2.

[0038] Example 4 A microcapsule emulsion based on natural plant materials, Example 1: 4.8g modified gum arabic, 300g deionized water, 1.2g loofah powder, 48g CYMEL385 amino resin and 220g fragrance.

[0039] The preparation method in this embodiment is the same as that in Example 2.

[0040] Example 5 A microcapsule emulsion based on natural plant materials is described in this embodiment. The formulation of the microcapsule emulsion in this embodiment is completely consistent with that in Example 2, except that the addition method of CYMEL385 amino resin is adjusted. The specific preparation steps are as follows: S1: Preparation of Primary Emulsifier Following the same procedure as in Example 2, step S1, a modified gum arabic aqueous solution containing loofah powder was obtained.

[0041] S2: Prepolymerization Stage Cool the main emulsifier to 40°C, add 1 / 3 of the CYMEL385 amino resin, and stir at low speed for 15 minutes to form a prepolymer mixture.

[0042] S3: Emulsification treatment Add 180g of fragrance and emulsify at 15000rpm for 3 minutes to obtain a stable emulsion.

[0043] S4: Crosslinking stage Add the remaining 2 / 3 of the CYMEL385 amino resin to the emulsion, adjust the pH to 4.0 with 10wt% citric acid aqueous solution, and heat to 60℃ and stir for 2 hours.

[0044] S5: Curing and post-treatment: Same as step 5 in Example 1, heat to 70°C and cure for 2 hours, adjust pH to 7.5 and then cool to obtain microcapsule emulsion.

[0045] Example 6 A microcapsule emulsion based on natural plant materials. The formulation of the microcapsule emulsion in this embodiment is completely consistent with that in Example 2. The specific preparation steps are as follows: S1: Preparation of primary emulsifier and addition of crosslinking agent Following the same steps S1-S2 as in Example 2, a mixed emulsion system containing CYMEL385 was obtained.

[0046] S2: Emulsification Following the same procedure as in Example 1, step S3, an oil-in-water emulsion is obtained.

[0047] S3 gradient polymerization reaction The emulsion was transferred to a top-mounted stirred reactor and stirred at a constant temperature of 40°C. The pH was adjusted to 5.0 with a 10wt% citric acid aqueous solution, and the mixture was stirred at this pH and temperature for 15 minutes. Then, the temperature was increased to 60°C at a rate of 1°C / min, while the pH was slowly adjusted to 4.0. The mixture was stirred at this constant temperature and pH for 2 hours. Finally, the temperature was increased to 70°C, the pH was further adjusted to 3.5, and the mixture was stirred continuously for 2 hours to complete the curing process.

[0048] S4: Post-processing Following the same procedure as in Example 2, step S5, the pH was adjusted to 7.5 and then cooled to obtain the microcapsule emulsion.

[0049] Example 7 A microcapsule emulsion based on natural plant materials is described in this embodiment. The formulation of the microcapsule emulsion in this embodiment is completely consistent with that in Example 2, except that the loofah powder is pretreated and modified. The specific preparation steps are as follows: S1: Modification of loofah powder: Place loofah powder in a 5wt% sodium hydroxide aqueous solution and soak at 60℃ for 2 hours, stirring 3 times for 10 minutes each time; then wash repeatedly with deionized water until the washing solution is neutral, dry in an oven at 60℃ for 12 hours, and pass through a 100-mesh sieve for later use.

[0050] S2: Preparation of the main emulsifier to post-treatment: The remaining steps are completely consistent with those in Example 1, and a modified loofah powder-enhanced microcapsule emulsion is obtained.

[0051] To test the performance of the microcapsule emulsion in this formulation, the following comparative example was set up: Comparative Example 1: The composition of this comparative microcapsule emulsion formula is as follows: 4.8g gum arabic, 270g deionized water, 32.5g CYMEL385 amino resin, and 180g fragrance.

[0052] The preparation steps of this comparative microcapsule emulsion are completely identical to those in Example 2, except that loofah powder is not added and unmodified gum arabic is used.

[0053] Comparative Example 2: A microcapsule emulsion comprising the following components: 4.8g modified gum arabic, 270g deionized water, 0.8g loofah powder, 32.5g gelatin, and 180g fragrance (using gelatin instead of CYMEL385 amino resin).

[0054] The preparation steps of this comparative microcapsule emulsion are completely the same as those in Example 2, except that gelatin is used instead of CYMEL385 and the crosslinking stage is maintained at 60°C and stirred for 3 hours.

[0055] Comparative Example 3 A microcapsule emulsion with a formulation composition completely identical to that of Example 2.

[0056] The preparation method of this comparative example is completely the same as that of Example 2, except that the CYMEL385 amino resin is added all at once after emulsification and the pH is directly adjusted to 4.0 and the temperature is raised to 60°C for reaction.

[0057] Experimental Example 1 To verify the technical effect of the optimized scheme of the present invention, performance tests were conducted on the microcapsule emulsions of Examples 2-7 and Comparative Examples 1-3. The test items included encapsulation efficiency, particle size distribution, morphological characteristics, stability and mechanical strength. The test methods and results are as follows.

[0058] 1. Testing Method Encapsulation efficiency determination: Solvent extraction combined with gas chromatography (GC) analysis was used. 1.0 g of microcapsule emulsion was accurately weighed, 10 mL of n-hexane was added, and ultrasonic extraction was performed for 30 minutes. After centrifugation at 3000 rpm for 15 minutes, the supernatant was collected for GC testing, and the free fragrance content was calculated. Encapsulation efficiency = (total fragrance content - free fragrance content) / total fragrance content × 100%. Each group of samples was tested in parallel for 3 times, and the average value was taken.

[0059] Particle size distribution analysis: Parameters such as D(4,3), D(3,2), and span value were measured using a laser particle size analyzer. D(4,3) is the volume-weighted average particle size in μm, reflecting the contribution of large particles to the overall particle size. A smaller value indicates a lower proportion of large particles in the system and a more homogeneous emulsion system. D(3,2) is the surface area-weighted average particle size in μm, reflecting the contribution of small particles to the overall particle size. A smaller value indicates a higher proportion of small particles and better emulsion dispersibility. Span value: The calculation formula is span = (D90 - D10) / D50. The smaller the value, the narrower the particle size distribution range and the better the uniformity of particle size.

[0060] Morphological observation: The microcapsule emulsion was freeze-dried and sputter-coated with gold using a scanning electron microscope (SEM). The surface morphology was observed at an accelerating voltage of 15kV and a magnification of 500-5000 to evaluate the morphological regularity, surface smoothness and damage.

[0061] Stability testing includes thermal stability (encapsulation retention rate measured after 7 days in a 60℃ oven) and storage stability (encapsulation rate measured periodically after 30 days at 25℃ and 60% relative humidity); mechanical strength testing.

[0062] 2. Test Results The test results are shown in Table 1.

[0063] Table 1. Test Results of Experimental Examples

[0064] 3. Results Analysis The performance test results of Example 1 show that the microcapsule emulsions based on natural plant materials prepared in Examples 2-7 of this invention are significantly superior to Comparative Examples 1-3 in terms of core indicators such as encapsulation efficiency, particle size distribution, and stability. This fully demonstrates the synergistic technical advantages of OSA-modified gum arabic, controlled dosage of loofah powder, and optimized polymerization process. Overall, the microcapsule emulsions in the example series exhibit high encapsulation efficiency, small particle size and narrow distribution, and excellent anti-aging ability, while the comparative examples generally suffer from low encapsulation efficiency, large and uneven particle size distribution, and insufficient stability. The performance differences between the two are significant. From the encapsulation efficiency index, the encapsulation efficiency of Examples 2-7 was maintained at 91%-95%, with Example 6 achieving the highest 95% thanks to the pH gradient polymerization process. Example 3 achieved an encapsulation efficiency of 94% with 0.8g of loofah powder. Even with an excess of 1.2g of loofah powder in Example 4, the encapsulation efficiency still reached 91%, far higher than the 73%-82% of Comparative Examples 1-3. This difference is mainly due to the excellent emulsifying properties of OSA-modified gum arabic. Compared with the unmodified gum arabic used in Comparative Example 1, the modified gum arabic can more efficiently stabilize the oil-water interface and reduce the free flow of fragrance core materials. At the same time, the porous structure of loofah powder can increase the adsorption sites of the wall material. The optimization effect is best when added in an appropriate amount. Excessive addition will lead to local agglomeration due to decreased dispersibility, slightly reducing the encapsulation efficiency. In contrast, Comparative Example 2 used gelatin instead of CYMEL385 amino resin, and the cross-linked wall material structure was loose, with the lowest encapsulation efficiency of only 73%.

[0065] The D(4,3) range of Examples 2-7 is 11.254-12.365 μm, the D(3,2) range is 4.285-4.810 μm, and the span value range is 2.568-2.921. Among them, the alkali-treated modified loofah powder in Example 7 has a D(4,3) as low as 11.320 μm and a D(3,2) as low as 4.285 μm. Example 6, using a pH gradient polymerization process, has a span value of only 2.568, showing the best particle size refinement and distribution uniformity. In contrast, the comparative examples have a D(4,3) range of 15.328-18.562 μm and a D(3,2) range of 4.285-4.810 μm. 2) The particle size range is 4.985-5.428 μm, and the span value range is 2.986-3.255. The particle size is significantly larger and the distribution range is wider. This is because the fiber structure of loofah powder can act as a crystal nucleus in the emulsification process, inhibiting oil droplet aggregation. Alkali treatment modification further improves the dispersibility of loofah powder and reduces the formation of large particles. Stepwise addition of crosslinking agents and pH gradient control can avoid local over-crosslinking reaction, prevent microcapsule aggregation, and thus reduce the span value. The comparative ratio lacks these optimization methods, and the oil droplets are easy to merge during the emulsification process, eventually forming microcapsules with large particle size and uneven distribution.

[0066] In terms of stability, the microcapsule emulsions of Examples 2-7 maintained a thermal stability of 90%-94% at 60°C and an encapsulation rate of 90%-93% after 30 days of storage at 25°C, with minimal performance degradation. The pH gradient process in Example 6 achieved a thermal stability retention of 94% and an encapsulation rate of 93% after storage, demonstrating strong anti-aging capabilities. In contrast, the comparative examples performed poorly, with a thermal stability retention of only 70%-79% and an encapsulation rate of 66%-75% after 30 days of storage. The core reason for this is that the wall material network structure formed by the cross-linking of CYMEL385 amino resin is dense, and its high temperature resistance and impermeability are superior to the gelatin cross-linking system of Comparative Example 2. At the same time, the composite wall material composed of modified gum arabic and loofah powder synergistically enhances structural stability and effectively inhibits core material leakage during long-term storage. Considering all performance indicators, the microcapsule emulsion prepared by the pH gradient polymerization process in Example 6, combined with OSA-modified gum arabic and an appropriate amount of loofah powder, exhibits the best overall performance. The encapsulation efficiency, stability, and particle size distribution uniformity all reach their peak values, fully demonstrating that the present invention effectively solves the technical bottlenecks of traditional microcapsule emulsions, such as low encapsulation efficiency, poor stability, and uneven particle size, through formula optimization and process control, and significantly improves the overall performance of the product.

[0067] Experiment Example 2 1. Test Object Examples 2-7 and Comparative Examples 1-3 were microcapsule emulsions used as test samples.

[0068] 2. Testers Ninety volunteers aged 18–55 years with normal sense of smell and no history of allergies were selected, including 45 men and 45 women. These volunteers were divided into 9 groups corresponding to the microcapsule emulsion samples of Examples 2–7 and Comparative Examples 1–3, with 5 men and 5 women in each group.

[0069] 3. Testing Methods Volunteers were tested in a standard sensory room. They smelled the corresponding microcapsule emulsion sample for 20 seconds and rated the aroma intensity and preference on a scale of 0-7. At the same time, the emulsion's effect on removing simulated odors was evaluated, and the average value was calculated after removing outliers.

[0070] 4. Test Results As shown in Table 2.

[0071] Table 2 Test Results of Experiment Example 2

[0072] The aroma characteristics and odor removal performance test data show that all microcapsule emulsions in the examples and comparative examples possess odor removal capabilities. The aroma intensity of Examples 2-7 is consistently between 4.0 and 4.6, with aroma preference scores all above 4.0, and Example 6 reaching a preference score of 5.0. In contrast, the aroma intensity of Comparative Examples 1-3 is slightly higher, with preference scores only between 3.2 and 3.8. This indicates that the technical solution of the present invention, while ensuring odor removal effectiveness, significantly improves the comfort and affinity of the aroma, solving the problem of low aroma preference scores in the comparative examples.

[0073] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a microcapsule emulsion based on natural plant materials, characterized in that, Includes the following steps: S1: Mix modified gum arabic with deionized water, and after the modified gum arabic is dissolved, add loofah powder and stir evenly to obtain the main emulsifier; S2: Add amino resin crosslinking agent to the main emulsifier and stir until uniform to obtain a mixture; S3: Add fragrance to the mixture and emulsify at 15000 rpm for 3 minutes to obtain an emulsion; S4: Adjust the pH of the emulsion to 4.0, heat to 60°C at a rate of 2°C / min, stir for 2 hours and maintain the pH between 3.5 and 4.5; S5: Heat to 70℃, stir at a constant temperature for 2 hours to solidify, adjust pH to 7.5, and cool naturally to room temperature to obtain microcapsule emulsion.

2. The method for preparing a microcapsule emulsion based on natural plant materials according to claim 1, characterized in that, The modified gum arabic in step S1 is prepared by the following method: Step 1: Mix gum arabic with deionized water, dissolve, and then cool for later use; Step 2: Mix octenyl succinic anhydride, Tween 80 and deionized water, and emulsify. Step 3: Add the solution obtained in step S2 dropwise to the gum arabic solution obtained in step S1 to carry out the grafting reaction, and adjust the pH during the reaction; Step 4: Adjust the pH to terminate the reaction; Step 5: The liquid after the reaction is terminated is concentrated, spray-dried and sieved in sequence to obtain modified gum arabic.

3. The method for preparing a microcapsule emulsion based on natural plant materials according to claim 1, characterized in that: In step S2, 1 / 3 of the amount of amino resin crosslinking agent is added to the main emulsifier, and the remaining amino resin crosslinking agent is added to the emulsion before adjusting the pH of the emulsion with a pH adjuster in step S4.

4. The method for preparing a microcapsule emulsion based on natural plant materials according to claim 1, characterized in that: Step S4 involves stirring at a constant temperature of 40°C, adjusting the pH to 5.0, and maintaining this temperature for 15 minutes; then increasing the temperature to 60°C at a rate of 1°C / minute, adjusting the pH to 4.0, and stirring at this constant temperature and pH for 2 hours.

5. The method for preparing a microcapsule emulsion based on natural plant materials according to claim 1, characterized in that: The loofah powder was pretreated with sodium hydroxide alkaline etching.

6. The method for preparing a microcapsule emulsion based on natural plant materials according to claim 1, characterized in that: The mass ratio of the modified gum arabic, deionized water, loofah powder, amino resin crosslinking agent and fragrance is 1: (56.25-62.5): (0.0875-0.25): (6.7-8.3): (37.5-42).

7. The method for preparing a microcapsule emulsion based on natural plant materials according to claim 1, characterized in that: The amino resin crosslinking agent is CYMEL385 amino resin.

8. A microcapsule emulsion based on natural plant materials, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 7.

9. The use of the microcapsule emulsion according to claim 8 in the preparation of textile cleaning and care products.

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