Organic-inorganic hybrid slow-release fragrance microcapsule and preparation method thereof

Abstract

This invention relates to the field of microencapsulation technology, and more specifically, to an organic-inorganic hybrid sustained-release fragrance microcapsule and its preparation method. By weight percentage, the components include: 10-35% fragrance oil, 1-10% silane precursor, 0.01-2% silane coupling agent, 1-15% polyisocyanate, 0.01-10% emulsifier, 0.01-10% polyamine compound, and deionized water to make up the balance. Through the combination of sol-gel and interfacial polymerization methods, the stability of the fragrance is improved, making it less prone to volatilization or decomposition during long-term storage or under different environments, effectively preventing direct contact between the fragrance and air, thereby prolonging the duration of the aroma. During use, the organic-inorganic hybrid fragrance microcapsule releases active substances through sustained release, reducing environmental pollution and diffusion.

Description

Technical Field

[0001] This invention relates to the field of microcapsule technology, specifically to an organic-inorganic hybrid sustained-release flavor microcapsule and its preparation method. Background Technology

[0002] Fragrances, with their pleasant aromas, can eliminate odors and improve people's quality of life, and are widely used in daily chemicals, food, healthcare, textiles, and clothing. However, fragrances are generally highly volatile substances, characterized by low boiling points, high volatility, short-lasting scents, and chemical reactivity. This makes the preservation of fragrances and their stability in added products a crucial issue of widespread concern. Fragrance microencapsulation utilizes modern technology to encapsulate fragrances, plant essential oils, and other raw materials using special materials and scientific methods to form microcapsule emulsions. This technology leverages the sealing effect of the capsule wall to effectively inhibit fragrance volatilization and improve the stability of fragrances during storage and use. Due to limitations imposed by the properties of fragrances and their intended use, the choice of shell materials is often limited. Existing technologies using suitable shell materials such as chitosan-gum arabic, lecithin, starch, and cellulose to prepare fragrance microcapsules suffer from low encapsulation efficiency, poor stability, and low fragrance loading capacity. Fragrance microcapsules prepared from organic polymers such as polyurea and polyurethane exhibit poor scent persistence.

[0003] Chinese invention patent CN106281676A discloses a microcapsule sustained-release fragrance. The fragrance is filled within the porous structure of a nano-core material, and a coating material encapsulates the fragrance-filled nano-core material to form the microcapsule sustained-release fragrance. The composition and content of the microcapsule sustained-release fragrance, by weight, are as follows: 5-15 parts nano-core material, 5-15 parts fragrance, and 70-90 parts coating material; the nano-core material is a porous resin or nano-silica; the coating material is pharmaceutical-grade PEG or monoglyceride. While the microcapsule sustained-release fragrance preparation method provided by this invention is simple and uses environmentally friendly raw materials, it suffers from poor shell-forming properties, a porous structure, and poor retention of low-molecular-weight fragrance active ingredients. Summary of the Invention

[0004] The first aspect of this invention provides an organic-inorganic hybrid sustained-release fragrance microcapsule, comprising, by weight percentage: 10-35% fragrance oil, 1-10% silane precursor, 0.01-2% silane coupling agent, 1-15% polyisocyanate, 0.01-10% emulsifier, 0.01-10% polyamine compound, and deionized water to make up the balance.

[0005] Preferably, by weight percentage, the components include: 20-35% essential oil, 1-4% silane precursor, 0.2-2% silane coupling agent, 1-6% polyisocyanate, 0.5-3% emulsifier, 0.5-2% polyamine compound, and deionized water to make up the balance.

[0006] Preferably, the content of the essential oil in the suspension of the microcapsules is 20-30 wt%.

[0007] More preferably, the content of the essential oil in the suspension of the microcapsules is 22-26 wt%.

[0008] Preferably, the weight ratio of the silane precursor to the silane coupling agent is 2:(0.2-2).

[0009] More preferably, the weight ratio of the silane precursor to the silane coupling agent is 2:(0.2-1.5).

[0010] The weight ratio of the polyisocyanate to the polyamine compound is (4-4.5):(0.5-2).

[0011] Preferably, the weight ratio of the polyisocyanate to the polyamine compound is (4-4.5):(0.8-1).

[0012] This study found that by limiting the weight ratio of polyisocyanate to polyamine compound to (4-4.5):(0.5-2), the uniformity of capsule shell particle size and thermal stability can be improved. This may be because the addition of polyamine can not only react with isocyanate to form a polymer shell, but also catalyze the hydrolysis-condensation reaction of precursor and silane coupling agent to form a silica shell on the droplet surface. The two reactions occur simultaneously, forming a specific organic-inorganic shell.

[0013] The essential oils include at least one of lavender essence, apple essence, rose essence, lemon essence, and fresh marine essence.

[0014] The silane precursor includes one or more of tetraethyl silicate, tetramethoxysilane, tetrapropyl silicate, tetramethylsilane, polydimethylsiloxane, polymethylsiloxane, and polyethyl silicate.

[0015] Preferably, the silane precursor comprises tetraethyl silicate and / or tetramethoxysilane.

[0016] The silane coupling agent includes one or more of methyltrimethoxysilane, methyltriethoxysilane, 3-aminopropyltriethoxysilane, and γ-aminopropylmethyldiethoxysilane.

[0017] Preferably, the silane coupling agent comprises methyltrimethoxysilane and / or 3-aminopropyltriethoxysilane.

[0018] The polyisocyanates include one or more of the following: isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, methylcyclohexane diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, phenyl diisocyanate, methylcyclohexyl diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate dimer, hexamethylene diisocyanate trimer, hexamethylene diisocyanate prepolymer, hexamethylene diisocyanate biuret, isophorone diisocyanate dimer, isophorone diisocyanate trimer, and diphenylmethane diisocyanate prepolymer.

[0019] Preferably, the polyisocyanate includes isophorone diisocyanate and / or hexamethylene diisocyanate trimer.

[0020] The emulsifier includes one or more of the following: polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, pectin, gum arabic, gelatin, Tween 80, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, phosphate, sodium polyacrylate, sodium carboxymethyl cellulose, dodecyl ammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, styrene-maleic anhydride copolymer, polyacrylamide, dimethyl diallyl ammonium chloride homopolymer, acrylamide and diallyl dimethyl ammonium chloride copolymer, and ethoxylated alkyl sulfate.

[0021] Preferably, the emulsifier comprises polyvinyl alcohol and / or hexadecyltrimethylammonium bromide.

[0022] Preferably, the polyvinyl alcohol comprises one of the following grades: Kuraray Co., Ltd. (Japan), PVA-217e; Guangzhou Zhonggao Chemical Co., Ltd., 088-10(1788); Shanghai Xiangpu-Mitsubishi Chemical eT-350; Tianjin Sindema Group Co., Ltd., Pertex 8850; and Tianjin Sindema Group Co., Ltd., Pertex 9213.

[0023] The polyamine compounds include one or more of the following: hexamethylenediamine, ethylenediamine, tetramethylethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenetetramine, diethylenetriamine, tris(2-aminoethyl)amine, dicyclohexylmethanediamine, methylcyclohexanediamine, 2,2-dimethyl-1,3-propanediamine, 1,3-cyclohexanedimethylenediamine, 1,2-diaminopropane, o-phenylenediamine, p-phenylenediamine, m-phenylenediamine, and polyethyleneimine.

[0024] Preferably, the polyamine compound includes 1,2-diaminopropane and / or polyethyleneimine.

[0025] Preferably, the polyethyleneimine includes one of the following grades: SP-006, SP-012, SP-018 from Shanghai Hanluo New Materials Co., Ltd.; GBK-PEI900, GBK-PEI7010 from Gongbike New Materials Technology (Shanghai) Co., Ltd.

[0026] A second aspect of this invention provides a method for preparing organic-inorganic hybrid sustained-release flavor microcapsules, comprising the following steps:

[0027] The silane precursor and silane coupling agent are mixed and pre-hydrolyzed using 15%-25% by weight of deionized water to obtain a mixed solution.

[0028] Polyisocyanate and essential oil are stirred and mixed evenly to form an oil phase. The emulsifier is dissolved by stirring with 20%-30% by weight of deionized water to form the first aqueous phase. The polyamine compound is dissolved by stirring with the remaining deionized water to form the second aqueous phase.

[0029] The oil phase is added to the mixed solution, followed by the first aqueous phase. The mixture is homogenized and emulsified to form an emulsion. The second aqueous phase is added dropwise to the emulsion, and the mixture is heated to carry out the reaction, resulting in a microcapsule suspension containing essential oils.

[0030] After the reaction is complete, the mixture is cooled, washed with water, filtered, and dried to obtain the flavor microcapsules.

[0031] The heating process includes a step-by-step heating process, specifically: the initial temperature is 20-35℃, and the temperature is increased by 8-12℃ for each subsequent step, followed by a holding time of 0.75-1.5h, until the temperature reaches 50-70℃.

[0032] Preferably, the initial temperature is 30-35℃, and for every 10℃ increase, the temperature is maintained for 0.75-1.5 hours until the temperature reaches 60-70℃.

[0033] A further preferred method is to start at 30°C, and hold for 1 hour for every 10°C increase in temperature, until the temperature reaches 60°C.

[0034] Beneficial effects

[0035] 1. By using a limited formula containing 10-35% essential oil, 1-10% silane precursor, 0.01-2% silane coupling agent, 1-15% polyisocyanate, 0.01-10% emulsifier, 0.01-10% polyamine compound, and deionized water to make up the balance, safe, non-toxic, biocompatible, and durable microcapsules are obtained.

[0036] 2. By limiting the weight ratio of silane precursor to silane coupling agent to 2:(0.2-2), the fragrance loading can be increased to 20-30wt%.

[0037] 3. By limiting the weight ratio of polyisocyanate to polyamine compound to (4-4.5):(0.5-2), the uniformity of capsule shell particle size and heat resistance can be improved.

[0038] 4. By combining sol-gel and interfacial polymerization methods, the stability of fragrances is improved, making them less prone to volatilization or decomposition during long-term storage or under different environments. This effectively prevents fragrances from directly contacting the air, thereby extending the duration of the aroma.

[0039] 5. This application prepares an organic-inorganic hybrid shell-coated fragrance oil, which provides dual protection for easily volatile oily fragrances, making the fragrance microcapsules usable in daily necessities, personal care products, textiles, pharmaceuticals and cosmetics. Attached Figure Description

[0040] Figure 1 The image shows a scanning electron microscope (SEM) image of the microcapsules prepared in Example 1.

[0041] Figure 2 The image shows the thermal analysis (TGA) diagram of the microcapsules prepared in Example 1. Detailed Implementation

[0042] Polyvinyl alcohol used in the examples: Guangzhou Zhonggao Chemical Co., Ltd., 088-10(1788); Polyethyleneimine: Shanghai Hanluo New Materials Co., Ltd., SP-012.

[0043] Example 1

[0044] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 26% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 1% silane coupling agent (methyltrimethoxysilane), 4% polyisocyanate (hexamethylene diisocyanate trimer and isophorone diisocyanate in a weight ratio of 1:1), 1.2% emulsifier (polyvinyl alcohol), 1% polyamine compound (polyethyleneimine, molecular weight 1200), and deionized water to make up the balance.

[0045] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0046] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0047] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 10wt% polyamine compound.

[0048] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0049] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0050] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0051] Example 2

[0052] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetramethoxysilane), 1% silane coupling agent (methyltrimethoxysilane), 4% polyisocyanate (hexamethylene diisocyanate trimer and isophorone diisocyanate in a weight ratio of 1:1), 1.2% emulsifier (polyvinyl alcohol), 1% polyamine compound (polyethyleneimine, molecular weight 1200), and deionized water to make up the balance.

[0053] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0054] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0055] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 10wt% polyamine compound.

[0056] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0057] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0058] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0059] Example 3

[0060] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 1.5% silane coupling agent (methyltrimethoxysilane), 4% polyisocyanate (hexamethylene diisocyanate trimer and isophorone diisocyanate in a weight ratio of 1:1), 1.2% emulsifier (polyvinyl alcohol), 1% polyamine compound (polyethyleneimine, molecular weight 1200), and deionized water to make up the balance.

[0061] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0062] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0063] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 10wt% polyamine compound.

[0064] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0065] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0066] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0067] Example 4

[0068] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 1% silane coupling agent (methyltrimethoxysilane), 4% polyisocyanate (hexamethylene diisocyanate trimer and isophorone diisocyanate in a weight ratio of 1:1), 1% emulsifier (hexadecyltrimethylammonium bromide), 1% polyamine compound (polyethyleneimine, molecular weight 1200), and deionized water to make up the balance.

[0069] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0070] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0071] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 10wt% polyamine compound.

[0072] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0073] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0074] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0075] Example 5

[0076] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 1% silane coupling agent (methyltrimethoxysilane), 4% polyisocyanate (hexamethylene diisocyanate trimer and isophorone diisocyanate in a weight ratio of 1:1), 1% emulsifier (hexadecyltrimethylammonium bromide), 0.8% polyamine compound (1,2-diaminopropane), and deionized water to make up the balance.

[0077] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0078] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0079] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 10wt% polyamine compound.

[0080] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0081] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0082] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0083] Example 6

[0084] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 0.2% silane coupling agent (methyltrimethoxysilane), 4.5% polyisocyanate (hexamethylene diisocyanate trimer and isophorone diisocyanate in a weight ratio of 2.5:2), 1.2% emulsifier (polyvinyl alcohol), 1% polyamine compound (polyethyleneimine, molecular weight 1200), and deionized water to make up the balance.

[0085] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0086] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0087] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 5wt% polyamine compound.

[0088] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0089] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0090] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0091] Example 7

[0092] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 0.2% silane coupling agent (3-aminopropyltriethoxysilane), 4.5% polyisocyanate (hexamethylene diisocyanate trimer and isophorone diisocyanate in a weight ratio of 2.5:2), 1% emulsifier (hexadecyltrimethylammonium bromide), 0.8% polyamine compound (polyethyleneimine, molecular weight 1200), and deionized water to make up the balance.

[0093] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0094] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0095] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 5wt% polyamine compound.

[0096] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0097] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0098] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0099] Example 8

[0100] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 0.2% silane coupling agent (3-aminopropyltriethoxysilane), 4.5% polyisocyanate (hexamethylene diisocyanate trimer and isophorone diisocyanate in a weight ratio of 2.5:2), 1% emulsifier (hexadecyltrimethylammonium bromide), 0.8% polyamine compound (1,2-diaminopropane), and deionized water to make up the balance.

[0101] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0102] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0103] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 5wt% polyamine compound.

[0104] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0105] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0106] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0107] Example 9

[0108] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 1% silane coupling agent (3-aminopropyltriethoxysilane), 4% polyisocyanate (hexamethylene diisocyanate trimer), 1.2% emulsifier (hexadecyltrimethylammonium bromide), 1% polyamine compound (polyethyleneimine, molecular weight 1200), and deionized water to make up the balance.

[0109] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0110] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0111] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 10wt% polyamine compound.

[0112] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0113] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0114] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0115] Example 10

[0116] An organic-inorganic hybrid sustained-release fragrance microcapsule, by weight percentage, comprises: 22% fragrance oil (lavender fragrance), 2% silane precursor (tetraethyl silicate), 1% silane coupling agent (3-aminopropyltriethoxysilane), 4% polyisocyanate (isophorone diisocyanate), 1.2% emulsifier (hexadecyltrimethylammonium bromide), 1% polyamine compound (polyethyleneimine, molecular weight 1200), and deionized water to make up the balance.

[0117] A method for preparing organic-inorganic hybrid sustained-release flavor microcapsules comprises the following steps:

[0118] (1) Mix the silane precursor and silane coupling agent, and pre-hydrolyze them with deionized water to obtain a mixed solution;

[0119] (2) Mix the polyisocyanate and essential oil evenly to form an oil phase. Dissolve the emulsifier with deionized water to form a first aqueous phase. Dissolve the polyamine compound with deionized water to prepare a second aqueous phase with a concentration of 10wt% polyamine compound.

[0120] (3) Add the oil phase to the mixed solution, then add the first aqueous phase, homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion, add the second aqueous phase dropwise to the emulsion while stirring at 500 rpm, and heat the reaction for 24 h to obtain a microcapsule suspension containing essential oils.

[0121] (4) After the reaction is complete, cool, wash with water, filter and dry to obtain the flavor microcapsules.

[0122] The heating is carried out in stages, specifically: the initial temperature is 30°C, and the temperature is increased by 10°C for 1 hour, until the temperature reaches 60°C.

[0123] Comparative Example 1

[0124] A polyurea shell fragrance microcapsule comprises the following raw materials in weight percentages: 22 wt% fragrance oil (lavender fragrance), 5 wt% isophorone diisocyanate, 0.8 wt% sodium dodecyl sulfate, 1.0 wt% polyethyleneimine (molecular weight 1200), and 71.2 wt% deionized water.

[0125] The preparation method of the above flavor microcapsules is as follows:

[0126] (1) Isophorone diisocyanate and fragrance are stirred evenly to form an oil phase.

[0127] (2) Sodium dodecyl sulfate is added to deionized water to form the first aqueous phase; polyethyleneimine is added to deionized water to prepare a polyethyleneimine solution with a concentration of 10wt% as the second aqueous phase for later use.

[0128] (3) Add the oil phase described in step (1) to the mixed solution in step (2), homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion. Pour the emulsion into a flask, stir at 500 rpm, slowly add polyethyleneimine solution, gradually raise the temperature to 70°C and stir for 12 h to obtain polyurea fragrance microcapsules.

[0129] Comparative Example 2

[0130] A sol-gel precursor for preparing silica-shell fragrance microcapsules comprises the following raw materials by mass percentage: 22 wt% fragrance oil (lavender fragrance), 5 wt% tetraethyl silicate, 0.6 wt% hexadecyltrimethylammonium chloride, and 72.4 wt% deionized water.

[0131] The preparation method of the above flavor microcapsules is as follows:

[0132] (1) Add hexadecyltrimethylammonium chloride to deionized water to form an aqueous phase.

[0133] (2) Mix the essential oil and tetraethyl silicate to form an oil phase.

[0134] (3) Add the oil phase to the aqueous phase and stir until homogeneous. Homogenize and emulsify at 3000 rpm for 5 min to form an O / W emulsion. Pour the emulsion into a flask, stir at 500 rpm, and react at 35°C for 48 h to obtain silica fragrance microcapsules.

[0135] Performance testing methods and data

[0136] The microcapsules prepared in Example 1 were characterized by electron microscopy and thermal analysis, such as... Figure 1 As shown, the microcapsule particle size distribution is uniform, such as Figure 2 As shown, the microcapsule decomposition temperature is approximately 300℃, which indicates the synthesis of organic-inorganic hybrid sustained-release flavor microcapsules.

[0137] Fragrance intensity evaluation: The sample was added to the base of unscented laundry detergent for evaluation: Fragrance microcapsule slurry (0.5wt%) was added to the base and stirred evenly to obtain microcapsule laundry detergent. 20g of microcapsule laundry detergent was added to 5L of water and poured into a small drum washing machine. A 40g 30×30cm cotton towel was placed inside and washed using the quick wash mode. After spin-drying, the towel was placed on a clothes rack and air-dried naturally in a clean, odor-free laboratory. Five experimenters checked the fragrance of the towel on days 1, 2, 3, 4, 5, 6, and 7, and rubbed the towel (a small area) to rate the fragrance intensity (5-point scale: 1 = very weak, 2 = weak, 3 = medium, 4 = strong, 5 = very strong). The rubbing force and number of times were kept consistent for each test. The scores from the five experimenters were tallied, and the average was calculated to obtain the comprehensive score. The fragrance intensity evaluation results obtained from the fragrance release test are shown in Table 1.

[0138] Table 1

[0139]

[0140] Table 1 shows that Examples 1-10 of this application achieved excellent aroma 7 days before and after kneading.

Claims

1. An organic-inorganic hybrid sustained-release flavor microcapsule, characterized in that, By weight percentage, the components include: 20-35% essential oil, 1-4% silane precursor, 0.2-2% silane coupling agent, 1-6% polyisocyanate, 0.5-3% emulsifier, 0.5-2% polyamine compound, and deionized water to make up the balance. The essential oil content in the microcapsule suspension is 20-30 wt%. The weight ratio of the silane precursor to the silane coupling agent is 2:(0.2-2). The weight ratio of the polyisocyanate to the polyamine compound is (4-4.5):(0.5-2); The organic-inorganic hybrid sustained-release fragrance microcapsule is described above. A method for preparing the organic-inorganic hybrid sustained-release fragrance microcapsule includes the following steps: The silane precursor and silane coupling agent are mixed and pre-hydrolyzed using 15%-25% by weight of deionized water to obtain a mixed solution. Polyisocyanate and essential oil are stirred and mixed evenly to form an oil phase. The emulsifier is dissolved by stirring with 20%-30% by weight of deionized water to form the first aqueous phase. The polyamine compound is dissolved by stirring with the remaining deionized water to form the second aqueous phase. The oil phase is added to the mixed solution, followed by the first aqueous phase. The mixture is homogenized and emulsified to form an emulsion. The second aqueous phase is added dropwise to the emulsion, and the mixture is heated to carry out the reaction, resulting in a microcapsule suspension containing essential oils. After the reaction is complete, the mixture is cooled, washed with water, filtered, and dried to obtain the flavor microcapsules. The heating process includes a step-by-step heating process, specifically: the initial temperature is 20-35℃, and the temperature is increased by 8-12℃ for each step, followed by a holding time of 0.75-1.5h, until the temperature reaches 50-70℃; The silane precursor includes one or more of tetraethyl silicate, tetramethoxysilane, tetrapropyl silicate, and tetramethylsilane.

2. The organic-inorganic hybrid sustained-release flavor microcapsule according to claim 1, characterized in that, The silane coupling agent includes one or more of methyltrimethoxysilane, methyltriethoxysilane, 3-aminopropyltriethoxysilane, and γ-aminopropylmethyldiethoxysilane.

3. The organic-inorganic hybrid sustained-release flavor microcapsule according to claim 1 or 2, characterized in that, The polyisocyanates include one or more of the following: isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, methylcyclohexane diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, phenyl diisocyanate, methylcyclohexyl diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate dimer, hexamethylene diisocyanate trimer, hexamethylene diisocyanate prepolymer, hexamethylene diisocyanate biuret, isophorone diisocyanate dimer, isophorone diisocyanate trimer, and diphenylmethane diisocyanate prepolymer.

4. The organic-inorganic hybrid sustained-release flavor microcapsule according to claim 3, characterized in that, The emulsifier includes one or more of the following: polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, pectin, gum arabic, gelatin, Tween 80, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, phosphate, sodium polyacrylate, sodium carboxymethyl cellulose, dodecyl ammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, styrene-maleic anhydride copolymer, polyacrylamide, dimethyl diallyl ammonium chloride homopolymer, acrylamide, diallyl dimethyl ammonium chloride copolymer, and ethoxylated alkyl sulfate.

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