Composite wall material of microcapsule, microcapsule using composite wall material and preparation method of microcapsule

Abstract

The invention discloses a composite wall material of a microcapsule, the microcapsule using the composite wall material and a preparation method of the microcapsule, and relates to the technical field of daily chemical products. The wall material of the microcapsule comprises polysiloxane, an epoxy-polyamine polymer and polyamide-amine, and the polysiloxane, the epoxy-polyamine polymer and the polyamide-amine are in covalent linkage. The essence microcapsule prepared from the composite wall material of the microcapsule has excellent friction aroma release performance and excellent stability.

Description

Technical Field

[0001] The invention relates to the technical field of daily chemical products, and in particular to a composite wall material of a microcapsule and a preparation method of the corresponding microcapsule. Background Art

[0002] Fragrance is an important ingredient that adds a specific aroma to products and enhances the sensory experience. It is not only used in daily chemicals, but also widely used in food, beverage, cosmetics and other industries. However, due to the high volatility and poor stability of flavors, they are prone to deterioration during storage, transportation and use, resulting in changes in fragrance and flavor, thereby reducing the utilization rate of flavors. In order to overcome these problems, microencapsulation technology is widely used in the encapsulation of flavors. This technology protects the flavors from environmental conditions such as temperature, humidity, light and oxygen by encapsulating them in tiny capsules, thereby reducing volatilization losses and oxidative deterioration. Microencapsulated flavors can maintain their original aroma and flavor, extend their service life, and improve their application value.

[0003] Microcapsule technology encapsulates active substances through a "core-wall material" structure, wherein the core material is a substance surrounded by a polymer shell, which can be a lipophilic, hydrophobic or hydrophilic compound, etc. The release rate of the core material and its diffusion through the capsule wall can be controlled by changing the wall composition and / or the crosslinking degree of the wall material, and the crosslinking degree of the wall material directly affects the strength and properties of the microcapsule wall. The wall materials used to encapsulate flavors or similar active substances usually use melamine formaldehyde, urea-formaldehyde or polyurea (Perignon, C. et al., Journal of Microencapsulation 2015, 32 (1), 1-15), because they have high mechanical strength, good impermeability and low cost, and have appropriate brittleness to break under friction pressure to release the flavor, providing a lasting and pleasant olfactory effect. However, these types of wall materials usually involve harmful substances (such as formaldehyde, isocyanate), which endanger the health of workers and users. In recent years, with the improvement of people's living standards and the enhancement of health awareness, consumers have an increasingly strong demand for alternative flavor microcapsules. Therefore, it is of great significance to develop new flavor microcapsules with good stability and good olfactory properties.

[0004] The biocompatibility and biodegradability of epoxy-polyamine polymers make them widely used in the fields of medical devices, biomedical materials and drug release systems (Li Zeyu et al., Materials Science 2024, 14 (8), 1159-1168). Patent CN118201703A discloses a core-shell microcapsule composition with certain biodegradability, wherein the microcapsule shell is mainly an epoxy-polyamine polymer formed by epoxide and polyamine, which is a type of alternative microcapsule that does not involve formaldehyde and isocyanate. Using the OECD 301F method for analysis, the polymer can be degraded by more than 60% within 45 days, showing good biodegradability. In addition, the fragrance microcapsules constructed by the epoxy-polyamine polymer also show good friction release performance, but the patent does not provide the stability data of the microcapsules constructed by the epoxy-polyamine polymer in the detergent.

[0005] In recent years, Vermenische Co., Ltd. has disclosed a type of polyamide-based fragrance microcapsules, whose microcapsule shells are mainly constructed of polyamide polymers formed by bis(poly)acyl chlorides and polyamines (CN115175759A, WO2023274788A1, CN117460573A, CN117813154A, US20240261750A1), which is another type of new microcapsules that do not involve formaldehyde and isocyanate. This type of polyamide microcapsules can still retain about 70% of the fragrance after being stored in a softener at 37°C for one month, showing a certain stability, but the stability in detergents with high surfactant content is not ideal.

[0006] The fragrance microcapsules constructed by the above-mentioned epoxy-polyamine polymer or polyamide do not involve toxic formaldehyde and isocyanate. Although they are beneficial to the environment and health, their stability and friction fragrance release performance are still far from those of microcapsules constructed by traditional materials such as melamine formaldehyde, urea-formaldehyde or polyurea, and their application is limited.

[0007] Usually, in order to enhance the heat resistance of microcapsules, researchers will use inorganic materials such as SiO2 as the wall material of microcapsules. Silica microcapsules have the characteristics of fragile capsule shells under friction pressure, good stability and environmental friendliness. However, according to research public literature (such as CN103263877B, CN113441095B, ​​CN114845804A, CN116710545A, CN117045516A, etc.), the particle size of silica microcapsules is generally less than 10μm, and there are also disadvantages such as high hardness and difficulty in adjustment. These disadvantages limit its use in the field of flavor microcapsules. However, compounding silica with organic polymer materials can overcome the shortcomings of silica microcapsules and organic wall material microcapsules to a certain extent, while retaining the advantages of both materials, thereby expanding their application range. For example, CN116920737A patent discloses a silica-polyurethane composite phase change microcapsule and its preparation method, which effectively overcomes the disadvantage of poor thermal conductivity of pure organic wall materials by combining the advantages of silica and polyurethane. This composite material not only improves the sealing and stability of the microcapsule, but also enhances its comprehensive performance; the polysiloxane, polyurethane and polyurea composite microcapsules disclosed in CN116786044A greatly improve their stability in detergents by means of interlayer covalent bonding. It can be seen that the microcapsules obtained by silica or polysiloxane composite organic wall materials combine the advantages of the two materials, not only have better thermal stability, but also effectively improve the sealing and stability of the microcapsules. This composite material can make up for the defects of the loss of core active substances caused by pores in the organic wall material, thereby improving the comprehensive performance of the microcapsules. Summary of the invention

[0008] The present invention aims to provide a microcapsule constructed of a composite wall material, wherein the composite wall material comprises polysiloxane, epoxy-polyamine polymer and polyamide-amine. The microcapsule is easy to synthesize, has the required stability in water or other challenging base materials (such as fabric washing liquid), and its polymer shell construction does not involve formaldehyde and isocyanate, and is a new type of microcapsule with excellent performance; the microcapsule can retain active substances (such as fragrances, essential oils or other oils), and the capsule shell is easy to break under friction pressure; and it has stability when stored in the form of a product before use; a basic feature of the microcapsule is to synthesize a microcapsule with a composite shell wall of polysiloxane, epoxy-polyamine polymer and polyamide-amine by interfacial polymerization and in situ polymerization, giving full play to the respective advantages of polysiloxane, epoxy-polyamine polymer and polyamide-amine materials. More specifically, the invention includes three significant features: (1) by combining polysiloxane, epoxy-polyamine polymer and polyamide-amine, the sealing performance and thermal stability of the microcapsule are enhanced, thereby preventing the core material from escaping during storage and use; (2) the composite polysiloxane, epoxy-polyamine polymer and polyamide-amine polymer materials are connected by covalent bonds, making the microcapsule shell stronger, with better sealing performance and easy to break under friction pressure, thereby improving the performance of the microcapsule in practical applications; (3) the construction of the wall material does not involve toxic substances such as formaldehyde and isocyanate, which is beneficial to the environment and health.

[0009] The present invention includes the following three aspects:

[0010] (I) Combining the respective advantages of polysiloxane, epoxy-polyamine polymer and polyamide-amine wall materials, polysiloxane, epoxy-polyamine polymer and polyamide-amine composite wall material fragrance microcapsules are constructed, giving the microcapsules excellent thermal stability and friction fragrance release performance. The microcapsules include: 1. A lipophilic / hydrophobic core; 2. A polymer wall material wrapped in the outer layer of the core; the polymer wall material includes polysiloxane, epoxy-polyamine polymer and polyamide-amine; wherein, the polysiloxane and the epoxy-polyamine polymer are covalently linked through the ring-opening reaction of the epoxy functional group in the polysiloxane and the amine active reactive group (primary amine or secondary amine functional group) in the epoxy-polyamine polymer, and the active reactive group (primary amine or secondary amine functional group) of the epoxy-polyamine part can also participate in the formation of covalent bonds between polyamide-amines. In this way, the polysiloxane, epoxy-polyamine polymer and polyamide-amine forming the wall material are connected by covalent bonds, thereby improving the coating of the wall material on the core material and the brittleness of the wall material, thereby improving its stability and friction fragrance release performance.

[0011] (II) Provide a method for preparing polysiloxane, epoxy-polyamine polymer and polyamide-amine composite wall material microcapsules. The method comprises: 1. preparing an oil-in-water (O / W) emulsion formed by an oil phase and an aqueous phase, wherein the oil phase comprises an epoxy resin compound and an alkoxysilane compound, and the aqueous phase comprises a stabilizer or an emulsifier (such as polyvinyl alcohol); 2. adding an amine compound and an acrylamide compound, heating the water-in-water emulsion under stirring, and forming a polymer capsule shell and a core encapsulated therein through interfacial polymerization and in-situ polymerization of the polymer to obtain the composite wall material microcapsule; wherein the formed polymer capsule shell comprises polysiloxane, epoxy-polyamine polymer and polyamide-amine. Specifically, alkoxysilane and tetraalkoxysilane with epoxy functional groups are used as polysiloxane sources to be hydrolyzed into silanol compounds, and dehydration condensation reaction or dealcoholization condensation reaction occurs between the silanol compounds to generate polysiloxane; epoxy-polyamine polymers are obtained by ring-opening reaction between epoxy groups and amine functional groups of epoxy resin compounds; polyamide-amines are obtained by Michael addition reaction between acrylamide and amine functional groups; polysiloxane, epoxy-polyamine polymers and polyamide-amines are connected by covalent bonds. The present invention finds that this method is applicable to a variety of active ingredients, can prepare microcapsules with excellent stability and friction release performance, and does not involve toxic substances formaldehyde and isocyanate in the process of wall material construction, which is friendly to workers and users.

[0012] (iii) Application of the microcapsules in the preparation of detergents.

[0013] Specifically, it is achieved through the following technical solutions.

[0014] Firstly, a wall material of a microcapsule is provided, which comprises polysiloxane, epoxy-polyamine polymer and polyamide-amine, wherein the polysiloxane, epoxy-polyamine polymer and polyamide-amine are covalently linked.

[0015] The polysiloxane is formed by dehydration or dealcoholization condensation reaction of an alkylsilanol compound obtained by hydrolysis of an alkoxysilane compound; the alkoxysilane compound is an alkoxysilane with an epoxy functional group, or a composition of an alkoxysilane with an epoxy functional group and a tetraalkoxysilane.

[0016] The epoxy-polyamine polymer is formed by the ring-opening reaction of the epoxy group of the epoxy resin compound and the amine compound; the epoxy resin compound is a compound having at least two epoxy functional groups, and the amine compound is a compound containing at least one primary amine or two secondary amine functional groups.

[0017] The polyamide-amine is formed by Michael addition reaction between an acrylamide compound and an amine compound; the polyamide-amine is formed by in-situ polymerization; the acrylamide compound is a compound having at least two acrylamide functional groups; the amine compound is a compound containing at least one primary amine or two secondary amine functional groups.

[0018] The polysiloxane and the epoxy-polyamine polymer are linked by a ring-opening reaction between the epoxy functional group in the polysiloxane and the primary amine or secondary amine functional group in the epoxy-polyamine polymer.

[0019] The epoxy-polyamine polymer and the polyamide-amine are covalently linked, including the epoxy functional group in the epoxy-polyamine polymer and the primary amine or secondary amine functional group in the polyamide-amine being covalently linked through a ring-opening reaction, and the acrylamide in the polyamide-amine and the primary amine or secondary amine functional group in the epoxy-polyamine polymer being covalently linked through a Michael addition reaction.

[0020] Preferably, the alkoxysilane having an epoxy functional group is selected from at least one of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane, epoxypropyltrimethoxysilane, epoxybutyltrimethoxysilane and 5,6-epoxyhexyltriethoxysilane.

[0021] Preferably, the tetraalkoxysilane is selected from at least one of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisobutoxysilane, tetraisopropoxysilane, tetra-sec-butoxysilane, di-tert-butoxydimethoxysilane, tetra(2-methoxy-1-methylethyl)silane, and tetra(2-ethylhexyloxy)silane.

[0022] Preferably, the epoxy resin compound is selected from at least one of a diepoxy functional compound, a triepoxy functional compound and a tetraepoxy functional compound.

[0023] In some specific embodiments, the epoxy resin compound can be selected from at least one of N,N,N',N'-tetraepoxypropyl-4,4'-diaminodiphenylmethane, P-(2,3-epoxypropoxy)-N,N-di(2,3-epoxypropyl)aniline, 2,2-bis-(4-glycolylaminophenyl)propane and glycidyl ether.

[0024] Preferably, the acrylamide compound has a structural formula of X-(-NH(C=O)-CH=CH2)n or X-(-NH(C=O)-C(CH3)=CH2)n, wherein n≥2, and X is a molecule connecting n acrylamide structural units.

[0025] More preferably, the acrylamide compound is selected from at least one of diacrylamide and triacrylamide.

[0026] In some specific embodiments, the acrylamide compound can be selected from at least one of N,N'-methylenebis(methyl)acrylamide, N,N'-methylenebis(acrylamide), N,N'-vinylbis(acrylamide), N,N'-vinylbis(methyl)acrylamide, 1,4-diacryloylpiperazine, and 1,3,5-triacryloylhexahydro-1,3,5-triazine.

[0027] Preferably, the amine compound is selected from alkyl monoprimary amine compounds (R-NH2); diprimary amine compounds (NH2(CH2) n NH2), wherein n is between 2 and 8, preferably n≤5; primary amine and diprimary amine compounds containing phenyl groups, such as benzylamine and p-(m-)phenylenediamine, etc.; aniline compounds, p-phenylenediamine, etc.; disecondary amine compounds and polyamine compounds and polymers containing secondary amines and primary amines, such as N,N'-dimethylethylenediamine, polyethyleneimine, etc., the average molecular weight of polyethyleneimine is 2000g / mol.

[0028] The composite wall material of the microcapsule contains 10-17% alkoxysilane compound, 14-35% epoxy resin compound, 10-23% acrylamide compound and 16-22% amine compound, based on the mass percentage of the raw materials.

[0029] In some other embodiments, the method further comprises depositing a polymer on the surface of the wall material of the microcapsule to modify the prepared microcapsule wall material. The polymer is a cationic polymer, such as quaternary ammonium salt-10, quaternary ammonium salt-2, dimethyldiallylammonium chloride / acrylamide copolymer and chitosan and its derivatives, and the addition amount thereof is 0.1-20% of the total amount of the polymer wall material.

[0030] The present invention also provides a microcapsule for encapsulating essence, comprising essence and the wall material of the microcapsule, wherein the essence is encapsulated in the wall material of the microcapsule.

[0031] Preferably, the microcapsule encapsulating the essence further comprises a core material, the core material is encapsulated in the wall material of the microcapsule, and the essence is located in the core material. More preferably, the mass ratio of the core material to the wall material is (1.2-5.4):1.

[0032] Preferably, the emulsifier is selected from at least one of gum arabic, polyvinyl alcohol, polyvinyl pyrrolidone, methyl cellulose and polyacrylamide; more preferably, polyvinyl alcohol, the alcoholysis degree of which is preferably 88% and the average molecular weight is 74800 g / mol.

[0033] The fragrance is selected from vanillin, linalool, ionone, methyl hexyl cinnamaldehyde, phenylethyl alcohol, citral, methyl dihydrojasmonate, geranyl acetate, vanillin, coumarin, peach aldehyde, coconut aldehyde, musk, propyl decalactone, ethyl vanillin, linalool, linalyl acetate, pinene, lavender oil, acetophenone, allyl hexanoate, anisyl acetate, benzyl benzoate, citronellol, benzyl alcohol, carvone, benzaldehyde, benzyl acetate, cymene, dihydrocoumarin, ethoxyethyl acetate, dihydrocoumarin, cyclohexyl acetate, 2-(benzylidene)octanol, oxy(phenyl)acetic acid 3,7-dimethylocta-2,6-dien-1-yl ester, α- Methyl-4-(1-methylethyl)phenylpropanal, (E)-3,7-dimethyl-2,6-octadien-1-ol, 3,7-dimethyl-2,6-octadien-1-yl hexadecanoate, ethyl furanone, eugenol, 4-(p-hydroxyphenyl)-2-butanone, grapefruit aldehyde, trans-2-heptenal, trans-2-hexenal, cis-3-hexenyl carboxylate, (3-methyl-4-phenylethoxybut-3-en-1-yl)benzene, isoeugenol methyl ether, p-hydroxybenzylacetone, cis-3-hexenyl acetate, cis-3-hexenol, isopropylmethylthiazole, lauric acid, linalool oxide, menthol, anthranilic acid methyl Ester, 2-methylbutyl acetate, 2-methylbutyrate, nerol, isopulegol, 3-hydroxy-4-methyl-5-ethyl-2(5H)furanone, 3-methoxy-4-((2-methoxy-2-phenylvinyl)oxy)benzaldehyde, 2-undecenal, 2-acetylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2-acetyl-2-thiazoline, methylthiopropanal, furfurylthiol, ethyl 3-methyl-3-phenylglycidate, ethyl 2-trans-4-cis-decadienoate, methyl sorbate, trans-3-(dodecylthio)-1-(2,6,6-trimethyl-3-cyclohexen-1-yl) -1-butanone, δ-decalactone, maltol, α-methyl-4-(1-methylethyl)phenylpropanal, 6-pentyl-2H-tetrahydropyran-2-one, 1-methyl-4-(1-methylethyl)-1,4-cyclohexadiene, 2-hydroxybenzoic acid hexyl ester, 3-phenyl-2-propene-1-ol, 3-hydroxy-4,5-dimethyl-2(5H)furanone, 1,1-dimethoxy-2,2,5-trimethyl-4-hexane, 2-methyl-3-furanthiol, 3-isobutyl-2-methoxypyrazine, rose oil, dipropylene glycol, 5-methylfurfural, 6,5,2-methylheptenone, and at least one of 1-methylthiohexanol.

[0034] The method for preparing the above-mentioned microcapsules encapsulating essence comprises the following steps:

[0035] (1) dissolving an emulsifier in water to prepare an aqueous phase;

[0036] (2) Mix the essence, alkoxysilane compound, and epoxy resin compound to form an oil phase; disperse the oil phase in the aqueous phase to form an oil-in-water emulsion;

[0037] (3) Add an amine compound and an acrylamide compound to the oil-in-water emulsion obtained in step (2) for curing to obtain a microcapsule slurry encapsulating the essence with a composite wall material.

[0038] Preferably, after step (3), a cationic polymer is further added to the microcapsule slurry.

[0039] Preferably, in step (3), an amine compound and an acrylamide compound are added and cured under a temperature of 40 - 70 °C with stirring.

[0040] Compared with the existing technology, the present invention has the following beneficial effects:

[0041] The present invention provides a new composite wall material for microcapsules, which can encapsulate a variety of hydrophobic / lipophilic oily core materials. The composite wall material of the microcapsules combines polysiloxane, epoxy-polyamine polymer, and polyamide-amine. The obtained microcapsules have appropriate size (29 μm < Dv50 < 58 μm) to meet the friction fragrance release performance requirements for encapsulating essence, and improve the coating property of the wall material, so that the obtained essence microcapsules still have excellent friction fragrance release ability after being stored in a laundry detergent at 45 °C for 28 days, showing excellent thermal stability; in addition, polysiloxane has good biocompatibility and is environmentally friendly, and no toxic substances such as formaldehyde and isocyanate are involved in the construction process of the epoxy-polyamine polymer and polyamide-amine wall materials, which is beneficial to the environment and health.

[0042] The microcapsules encapsulating essence in the present invention are dispersed in the aqueous phase through an oil-in-water emulsion, and a polymer wall material is formed around the oil droplets to obtain a microcapsule structure with a composite wall material coating the core material. In addition to improving the structural strength of the wall material polymer, it also greatly improves the coating property of the wall material on the core material, so as to well protect the core material from leakage and loss, and control the size of the microcapsules, so as to have better deposition effect and friction fragrance release performance on substrates such as fabrics, skin, and hair.

[0043] Therefore, the wall material of the microcapsules in the present invention and the microcapsules applied are based on a composite wall material composed of polysiloxane, epoxy-polyamine polymer, and polyamide-amine, which are connected by covalent bonds. The essence microcapsules formed by this composite wall material have excellent friction fragrance release characteristics and thermal stability. Description of the Drawings

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0045] Figure 1 This is an optical microscopic image of the microcapsule encapsulating the flavor provided in Example 1 of the present invention.

[0046] Figure 2 This is an optical microscopic image of the microcapsules encapsulating the flavor provided in Example 2 of the present invention.

[0047] Figure 3 This is an optical microscopic image of the microcapsules encapsulating the flavor provided in Example 15 of the present invention. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Table 1 lists the compound categories, names and abbreviations of the raw materials used in the examples / comparative examples.

[0050] Table 1 Comparison table of compound names and abbreviations

[0051]

[0052] In the examples and comparative examples, the composition of the essential oils used is shown in Table 2.

[0053] Table 2 Essential oil composition

[0054]

[0055]

[0056] The general procedure steps for preparing microcapsules for encapsulating flavors include:

[0057] (1) dissolving an emulsifier in water to prepare an aqueous phase W;

[0058] (2) dispersing an alkoxysilane compound and an epoxy resin compound in essential oil to obtain an oil phase O;

[0059] (3) gradually adding the oil phase O obtained in step (2) to the water phase W prepared in step (1), and using mechanical stirring to disperse the oil phase in the water phase to form an oil-in-water (O / W) emulsion;

[0060] (4) adding an amine compound and an acrylamide compound to the oil-in-water (O / W) emulsion obtained in step (3), and performing a polymerization reaction at 40-70° C. under stirring to solidify the wall material, thereby obtaining a fragrance microcapsule slurry having a composite wall material;

[0061] (5) adding the cationic polymer to the flavor microcapsule slurry obtained in step (4), and stirring to uniformly disperse the cationic polymer in the slurry;

[0062] (6) After cooling to room temperature, the material is discharged and the microcapsules are collected to obtain microcapsules encapsulating the essence.

[0063] According to the above method, microcapsules encapsulating essences of Examples 1 to 15 were prepared. In Examples 1 to 15, the amount of emulsifier PVA was 1.8 g, dissolved in 30 g of water to prepare the aqueous phase W, the amount of essential oil was 20 g, the amount of cationic polymer was 0.5 g, and the ingredients of alkoxysilane compound, epoxy resin compound, amine compound, and acrylamide compound were shown in Table 3.

[0064] Table 3 Ingredients for preparing microcapsules encapsulating flavors in Examples 1-15

[0065]

[0066]

[0067] Comparative Example

[0068] The preparation method of the microcapsules of Comparative Examples 1-3 adopts the same preparation method as that of Example 1, and the ingredients of the alkoxysilane compound, epoxy resin compound, amine compound, and acrylamide compound are shown in Table 4. Specifically, compared with Example 1, in Comparative Example 1, no acrylamide compound is added so that no polyamide-amine polymer is formed in the wall material (Note: because no acrylamide compound is added, the amine compound reacting with the acrylamide compound is correspondingly reduced relative to Example 1); in Comparative Example 2, no epoxy resin compound is added so that no epoxy-polyamine polymer is formed in the wall material (Note: because no epoxy resin compound is added, the amine compound reacting with the epoxy resin compound is correspondingly reduced relative to Example 1); in Comparative Example 3, no tetraethoxysilane (TEOS) is added so that the content of the formed polysiloxane is greatly reduced.

[0069] Table 4 Ingredients for preparing microcapsules in Comparative Examples 1-3

[0070]

[0071] Measurement of Microcapsule Particle Size

[0072] Test method: The particle size was measured using a Malvern Mastersizer 2000s particle size analyzer. 10 g of the samples of Examples 1-15 and Comparative Examples 1-3 were respectively taken and dispersed in 40 g of deionized water, and stirred evenly to form a suspension. The suspension was dropped into the degassed circulating water connected to the scattering cell and measured. Dv(50) corresponds to the median of the distribution and is used as a measure of the volume average size of the microcapsules; according to the experience of those skilled in the art, when 20 μm < Dv50 < 60 μm, the microcapsule size is more suitable for the friction fragrance release function. The specific measurement results are shown in Table 5 below.

[0073] Table 5 Dv50 Test Results of Microcapsules in Examples 1-15 and Comparative Examples 1-3

[0074]

[0075]

[0076] The optical micrograph of the microcapsules encapsulating fragrance in Example 1 is as Figure 1 shown; the optical micrograph of the microcapsules encapsulating fragrance in Example 2 is as Figure 2 shown; the optical micrograph of the microcapsules encapsulating fragrance in Example 15 is as Figure 3 shown.

[0077] As can be seen from Table 5, the microcapsules prepared by the present invention are in the range of 29 μm < Dv50 < 58 μm, indicating that this method is suitable for the preparation of fragrance microcapsules, especially suitable for the preparation of microcapsules that require friction fragrance release performance.

[0078] Microcapsule Performance Test

[0079] 1) Friction Fragrance Release Performance Test of Microcapsules

[0080] Test method: 5 g of the microcapsule samples of Examples 1-15 and Comparative Examples 1-3 were respectively taken and dispersed in 45 g of deionized water, and stirred evenly to form a suspension. 4 g of the suspension was respectively added to 96 g of the laundry detergent base without fragrance, and stirred evenly until there was no agglomeration state to obtain a series of laundry detergent samples containing microcapsules. 10 g of the laundry detergent samples were respectively dissolved in 2 L of water, a towel (30 cm × 30 cm square towel) was added thereto, soaked for 15 minutes, hand-rubbed and washed 10 times, wrung dry, rinsed twice with 2 L of water, and naturally dried (for more than 6 hours), and the fragrance of the towel before and after friction was evaluated.

[0081] The fragrance intensity was evaluated by 4 professional fragrance evaluation members, and the score for the fragrance intensity was from 0 to 5 points, and the scoring criteria are shown in Table 6 below.

[0082] Table 6 Fragrance evaluation standards

[0083] Score Fragrance level 0 No fragrance 1 A faint scent 2 Light fragrance 3 Stronger aroma 4 Rich aroma 5 Very strong fragrance

[0084] The friction fragrance-releasing performance of the microcapsules was evaluated by comparing the fragrance levels of the towels before and after friction. The specific evaluation results are shown in Table 7 below.

[0085] Table 7 Evaluation results of friction fragrance release performance of microcapsules obtained in Examples 1-15 and Comparative Examples 1-3

[0086] sample Before friction After friction sample Before friction After friction Example 1 0 4 Example 10 0 3 Example 2 0 3.5 Embodiment 11 0 4 Example 3 0 4 Example 12 0 3.5 Example 4 0 3 Embodiment 13 0 4 Example 5 0 4 Embodiment 14 0 4 Example 6 0 4 Embodiment 15 0 3.5 Example 7 0 3.5 Comparative Example 1 0 0.5 Example 8 0 3 Comparative Example 2 0 1 Example 9 0 4 Comparative Example 3 0 2

[0087] As can be seen from Table 7, the composite microcapsules prepared by the present invention have excellent friction fragrance release performance, and the fragrance scores of the towels washed and rubbed by the present invention are all above 3 points. Comparing Examples 1-4, it is found that the introduction of phenyl groups into the epoxy-polyamine polymer can improve the friction fragrance release performance; in Examples 8 and 9, it is found that the friction fragrance release performance is also weakened by reducing the thickness of the wall material. In Comparative Examples 1-3, the lack of polyamide-amine or the lack of epoxy-polyamine polymer or the reduction of polysiloxane content all affect the brittleness of the wall material, thereby reducing the friction fragrance release performance of the obtained microcapsules; this shows that the function of the microcapsule wall material requires the joint action of these materials, and reducing any one of them will affect the overall brittleness of the wall material, thereby affecting the friction fragrance release performance of the microcapsules.

[0088] 2) Stability test of microcapsules

[0089] When microcapsules are mixed into consumer products, such as laundry detergent, and stored for a period of time, if the functions of the consumer products themselves do not change and the microcapsules in the consumer products still have good friction fragrance release performance, then the microcapsules are considered to have good stability.

[0090] Test method: Place the laundry detergent sample of the microcapsule obtained above at 45°C for 28 days. Take 10g of the laundry detergent sample and dissolve it in 2L of water. Add a towel (30cm×30cm square towel) and soak it for 15 minutes. Rub it by hand and wash it 10 times. After wringing it out, rinse it twice with 2L of water. After drying it naturally (for more than 6 hours), evaluate the fragrance of the towel before and after rubbing.

[0091] The stability of the microcapsules was evaluated by comparing the fragrance levels of the towels before and after rubbing. The specific evaluation results are shown in Table 8 below.

[0092] Table 8 Evaluation results of friction fragrance release performance of microcapsules obtained in Examples 1-15 and Comparative Examples 1-3

[0093] sample Before friction After friction sample Before friction After friction Example 1 0 3.5 Example 10 0 2.5 Example 2 0 3 Embodiment 11 0 3.5 Example 3 0 2.5 Example 12 0 3 Example 4 0 2.5 Embodiment 13 0 2.5 Example 5 0 3.5 Embodiment 14 0 3.5 Example 6 0 3.5 Embodiment 15 0 2.5 Example 7 0 3 Comparative Example 1 0 0 Example 8 0 2.5 Comparative Example 2 0 0 Example 9 0 3 Comparative Example 3 0 1.5

[0094] It can be seen from the test results in Table 8 that the fragrance microcapsules involved in the present invention (whose capsule shell is composited with multiple polymer materials such as polysiloxane, epoxy-polyamine polymer and polyamide-amine, and each material is linked by a covalent bond) have a fragrance burst of more than 2.5 points in the laundry detergent samples after being placed at 45°C for 28 days, and some (Examples 1, 5, 6, 11 and 14) reach 3.5 points, showing excellent thermal stability. Comparing Example 1 and Comparative Example 3 in Tables 7 and 8, it is found that the reduction of polysiloxane materials not only affects the friction fragrance release performance of the microcapsules, but also has a great effect on the stability in the laundry detergent. Compared with other epoxy-polyamine fragrance microcapsules (Tables 7 and 8, Comparative Example 1) and polyamide-amine microcapsules (Tables 7 and 8, Comparative Example 2), the fragrance microcapsules of the present invention have better friction fragrance release performance and better stability in laundry detergent.

[0095] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A composite wall material for microcapsules, characterized in that: The invention comprises polysiloxane, epoxy-polyamine polymer and polyamide-amine, wherein the polysiloxane, epoxy-polyamine polymer and polyamide-amine are linked by covalent bonds.

2. The composite wall material of microcapsules according to claim 1, characterized in that: The polysiloxane is formed by dehydration or dealcoholization condensation reaction of alkylsilanol compounds obtained by hydrolysis of alkoxysilane compounds; the alkoxysilane compounds are alkoxysilanes with epoxy functional groups, or a combination of alkoxysilanes with epoxy functional groups and tetraalkoxysilanes.

3. The composite wall material of microcapsules according to claim 2, characterized in that: The epoxy-polyamine polymer is formed by the ring-opening reaction of the epoxy group of the epoxy resin compound and the amine compound; the epoxy resin compound is a compound having at least two epoxy functional groups, and the amine compound is a compound containing at least one primary amine or two secondary amine functional groups.

4. The composite wall material of microcapsules according to claim 3, characterized in that: The polyamide-amine is formed by Michael addition reaction between an acrylamide compound and an amine compound; the polyamide-amine is formed by in-situ polymerization; the acrylamide compound is a compound having at least two acrylamide functional groups; the amine compound is a compound containing at least one primary amine or two secondary amine functional groups.

5. The composite wall material of microcapsules according to claim 4, characterized in that: The polysiloxane and the epoxy-polyamine polymer are linked by a ring-opening reaction between the epoxy functional group in the polysiloxane and the primary amine or secondary amine functional group in the epoxy-polyamine polymer.

6. The composite wall material of microcapsules according to claim 4, characterized in that: The epoxy-polyamine polymer and the polyamide-amine are covalently linked, including the epoxy functional group in the epoxy-polyamine polymer and the primary amine or secondary amine functional group in the polyamide-amine being covalently linked through a ring-opening reaction, and the acrylamide functional group in the polyamide-amine and the primary amine or secondary amine functional group in the epoxy-polyamine polymer being covalently linked through a Michael addition reaction.

7. The composite wall material of microcapsules according to claim 2, characterized in that: The alkoxysilane having epoxy functional group is selected from at least one of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane, epoxypropyltrimethoxysilane, epoxybutyltrimethoxysilane and 5,6-epoxyhexyltriethoxysilane.

8. The composite wall material of microcapsules according to claim 2, characterized in that: The tetraalkoxysilane is selected from at least one of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisobutoxysilane, tetraisopropoxysilane, tetra-sec-butoxysilane, di-tert-butoxydimethoxysilane, tetra(2-methoxy-1-methylethyl)silane and tetra(2-ethylhexyloxy)silane.

9. The composite wall material of microcapsules according to claim 3, characterized in that: The epoxy resin compound is selected from at least one of a diepoxy functional compound, a triepoxy functional compound and a tetraepoxy functional compound.

10. The composite wall material of microcapsules according to claim 3, characterized in that: The epoxy resin compound is selected from at least one of N,N,N',N'-tetraepoxypropyl-4,4'-diaminodiphenylmethane, P-(2,3-epoxypropoxy)-N,N-di(2,3-epoxypropyl)aniline, 2,2-bis-(4-glycolylaminooxyphenyl)propane and glycidyl ether.

11. The composite wall material of microcapsules according to claim 5, characterized in that: The structural formula of the acrylamide compound is X-(-NH(C=O)-CH=CH2)n or X-(-NH(C=O)-C(CH3)=CH2)n, wherein n≥2, and X is a molecule connecting n acrylamide structural units.

12. The composite wall material of microcapsules according to claim 5, characterized in that: The acrylamide compound is selected from at least one of N,N'-methylenebis(methyl)acrylamide, N,N'-methylenebis(acrylamide), N,N'-vinylbis(acrylamide), N,N'-vinylbis(methyl)acrylamide, 1,4-diacryloylpiperazine and 1,3,5-triacryloylhexahydro-1,3,5-triazine.

13. The composite wall material for microcapsules according to any one of claims 3 to 6, characterized in that: The amine compound is selected from at least one of alkyl monoprimary amine compounds, diprimary amine compounds, phenyl-containing primary and diprimary amine compounds, aniline compounds, disecondary amine compounds, and polyamine compounds and polymers containing secondary and primary amines.

14. The composite wall material for microcapsules according to any one of claims 4 to 13, characterized in that: Calculated by the mass percentage of the raw materials, the content of the alkoxysilane compound is 10-17%, the content of the epoxy resin compound is 14-35%, the content of the acrylamide compound is 10-23%, and the content of the amine compound is 16-22%.

15. A microcapsule encapsulating a flavor, characterized in that: The invention comprises a composite wall material of a microcapsule and an essence, wherein the essence is encapsulated in the wall material of the microcapsule.

16. The method for preparing microcapsules encapsulating essence according to claim 15, characterized in that: The following steps are involved: (1) dissolving an emulsifier in water to prepare an aqueous phase; (2) mixing the essence, the alkoxysilane compound, and the epoxy resin compound to form an oil phase; dispersing the oil phase in the water phase to form an oil-in-water emulsion; (3) adding an amine compound and an acrylamide compound to the oil-in-water emulsion obtained in step (2) for solidification to obtain a microcapsule slurry having a composite wall material and encapsulating the flavor.

17. The method for preparing microcapsules encapsulating essence according to claim 16, characterized in that: After the step (3), the method further includes adding a cationic polymer to the microcapsule slurry.

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