A simple preparation method of solid microcapsules with high encapsulation efficiency

Abstract

The application relates to a simple preparation method of solid microcapsules with high encapsulation efficiency, and the steps are as follows: (1) core phase a is added into continuous phase b, and pre-dispersion is carried out into emulsion E1 at a shearing rate of not less than 4000 r / min; (2) intermediate phase c is added into the emulsion E1 to obtain emulsion E2; (3) the emulsion E2 is dispersed at a shearing rate of not less than 4000 r / min to obtain emulsion E3; (4) the emulsion E3 is subjected to photo-crosslinking solidification to obtain solid microcapsules; the core phase a, the continuous phase b and the intermediate phase c are mutually immiscible; the intermediate phase c comprises photo-crosslinkable shell material monomers or photo-crosslinkable polymers; the sum of the interfacial tension of the intermediate phase c and the core phase a and the interfacial tension of the intermediate phase c and the continuous phase b is less than the interfacial tension of the core phase a and the continuous phase b; the average diameter of the solid microcapsules is 1-20 mu m, and the encapsulation efficiency of the solid microcapsules is more than 95%. The method is simple, and the size of the prepared product is controllable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microcapsules, and relates to a simple preparation method of solid microcapsules with high encapsulation efficiency. BACKGROUND

[0002] In order to avoid the loss of active functional components in practical application, the encapsulation of active components has great research and application value in medicine, pesticide, food, textile, cosmetics, building materials and printing and the like. The microcapsule technology is a method of encapsulating core materials by using film-forming materials as wall materials, which can effectively isolate the core materials from the external environment and prevent the influence of the external environment.

[0003] The microcapsule preparation methods are generally divided into physical methods, chemical methods and physical-chemical methods. In industrialized batch preparation, emulsification technology is usually used. These methods are usually prepared in a water-oil two-phase system, the hydrophobic phase is dispersed in the aqueous medium or the aqueous phase is dispersed in the hydrophobic oil or wax medium to form an emulsion, a stirrer or a homogenizer is used to emulsify the two phases, a surfactant, a lipid or a polymer emulsifier is used at the interface to stabilize, and a polymer monomer is cross-linked and deposited on the surface of the droplet in the dispersed phase or the continuous phase to form a film. The boundary is not clear, and a clear core-shell structure cannot be formed, resulting in low encapsulation efficiency. Or the monomers are located in the two phases, and the polymer is formed by polymerization between the two phases to encapsulate the substances to be encapsulated. However, the film formed will hinder the further polymerization of the polymer monomer, affecting the film thickness. In patent CN110062779A, microcapsules are prepared by using different viscosities. However, the morphology of the microcapsules in the emulsion cannot be accurately controlled, and a semi-coated state may be formed, resulting in low encapsulation efficiency of the microcapsules.

[0004] In addition, these methods have a relatively complicated process, high equipment requirements, many process parameter influencing factors, and produce microcapsules with large particle size and polydispersity, which are not easy to control the particle size. SUMMARY

[0005] The purpose of the application is to solve the above problems in the prior art, and provide a simple preparation method of solid microcapsules with high encapsulation efficiency.

[0006] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0007] A simple preparation method of solid microcapsules with high encapsulation efficiency, comprising the following steps:

[0008] (1) adding core material phase a into continuous phase b, and pre-dispersing into a continuous phase emulsion containing core material phase droplets at a certain shear rate, denoted as emulsion E1;

[0009] (2) adding intermediate phase c into emulsion E1, usually drop by drop, to obtain a double emulsion, denoted as emulsion E2;

[0010] (3) high speed shearing dispersion is performed on the emulsion E2, so that the intermediate phase c droplets diffuse to the surface of the core material phase a droplets under the driving of the interfacial tension to form a stable dispersed core-shell coated configuration, to obtain a double emulsion containing droplets with controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0011] (4) the emulsion E3 is subjected to photo-crosslinking curing to obtain solid microcapsules with core-shell structure dispersed in the continuous phase b, and then water washing, filtration and drying are performed to obtain the solid microcapsules;

[0012] The core material phase a and the continuous phase b in step (1), and the intermediate phase c in step (2) are mutually immiscible; the immiscibility between the core material phase a and the continuous phase b can avoid the migration of the active ingredient from the core material phase a to the continuous phase b; the immiscibility between the intermediate phase c and the core material phase a can avoid the migration of the active ingredient in the core material phase a to the intermediate phase b; and the immiscibility between the intermediate phase c and the continuous phase b can prevent the mixing between the intermediate phase c and the continuous phase b, thereby maintaining the stability of the emulsion E2;

[0013] The intermediate phase c contains a photo-crosslinkable shell material monomer or a photo-crosslinkable polymer;

[0014] The sum of the interfacial tensions of the intermediate phase c with the core material phase a and with the continuous phase b is less than the interfacial tension between the core material phase a and the continuous phase b (the interfacial tension between liquids is determined by a full-automatic surface tension instrument);

[0015] The shearing speed in step (1) and the shearing speed in step (3) are both not less than 4000 r / min;

[0016] The average diameter of the solid microcapsules is 1-20 μm, preferably 2-10 μm (measured by optical microscopy or by TEM or by light diffusion technology), and the encapsulation efficiency of the solid microcapsules is above 95% (the encapsulation efficiency is calculated by the ratio of the actual core material encapsulation rate to the theoretical core material encapsulation rate).

[0017] The present application is based on the relationship between the interfacial tension determining the emulsion configuration, different interfacial tension relationships can form different emulsion configurations, thereby the required interfacial tension relationship of the core-shell configuration can be used to encapsulate the required substances to form microcapsules with high encapsulation efficiency. In the prior art, encapsulation is completed by using different viscosities, but the interfacial tension between them is not clearly defined and described, if the interfacial tension does not meet the requirements of the core-shell coated configuration, a semi-coated state may be formed, resulting in incomplete encapsulation, thereby leading to low encapsulation efficiency of the microcapsules.

[0018] As a preferred technical solution:

[0019] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, in step (1), the temperature of the core phase a is 0-100℃, preferably 10-80℃, preferably 20-60℃, and the temperature of the continuous phase b is 0-100℃, preferably 10-80℃, preferably 20-60℃; in order to ensure that the interfacial tension in the actual operation is consistent with that measured by the instrument (measured at a certain temperature), preferably, the temperature of the core phase a is the same as that of the continuous phase b, and the consistent temperature of the other two is also conducive to the accurate optimization of the process conditions, and the different temperatures may deviate from the theoretical mechanism, affecting the encapsulation efficiency; in step (2), the temperature of the intermediate phase c is 20-60℃, and the temperature of the emulsion E1 is 20-60℃.

[0020] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, the core phase a is a liquid active material that needs to be encapsulated or a solution containing an active material in a dissolved form;

[0021] The continuous phase b comprises at least one branched polymer, and the branched polymer can increase the viscosity of the continuous phase, and the number average molecular weight of the branched polymer is greater than 5000 g / mol;

[0022] The intermediate phase c further comprises an initiator, or further comprises a surfactant and a crosslinking agent, and the crosslinking agent can make the formed shell material more dense.

[0023] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, the viscosity of the continuous phase b is higher than that of the core phase a, which can slow down the de-stabilization rate of the pre-dispersed core phase a droplets and improve the stability of the emulsion droplets obtained after pre-dispersion; the viscosity of the intermediate phase c is higher than that of the core phase a, which slows down the de-stabilization rate of the emulsion E2, allowing the encapsulation structure of the microcapsule to polymerize before the emulsion is de-stabilized, and once the polymerization is completed, it is thermodynamically stable.

[0024] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, the volume ratio of the core phase a to the continuous phase b is 1:5-20, preferably 1:6-10; the volume ratio of the intermediate phase c to the core phase a is between 1:10 and 10:1, preferably between 1:3 and 5:1, more preferably between 1:3 and 3:1, which can be used to control the shell material thickness of the polymerized microcapsule.

[0025] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, the mass content of the photo-crosslinkable shell material monomer or the photo-crosslinkable polymer in the intermediate phase c is 55-99%, the mass content of the initiator is 0.5-5%, the mass content of the surfactant is 0-20%, and the mass content of the crosslinking agent is 0-20wt%.

[0026] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, the photo-crosslinkable shell material monomer is a monomer with a reactive functional group, the photo-crosslinkable polymer is a polyether, polyurethane, polyester, polyethylene glycol, polypropylene glycol, polyimide, polyamide, polyolefin, polydimethylsiloxane, polyacetal, polyurea or polysulfide with a reactive functional group, the reactive functional group refers to one or more of the reactive functional groups contained in acrylate, methacrylate, vinyl ether, N-vinyl ether, mercaptoester, thioalkene, siloxane, epoxy, oxetane, urethane, isocyanate and peroxide; the initiator is an ultraviolet light initiator or a blue light initiator, the surfactant is an anionic surfactant, a non-ionic surfactant, an anionic-non-ionic surfactant, an amphoteric surfactant or an anionic-cationic mixed surfactant, including, for example, stearic acid, sodium dodecylbenzenesulfonate, sodium carboxymethylcellulose, fatty acid sorbitan (Span), polysorbate (Tween), sodium dodecyl sulfate and the like; the crosslinking agent is a compound with two or more functional groups capable of crosslinking the photo-crosslinkable shell material monomer and / or the photo-crosslinkable polymer.

[0027] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, the ultraviolet light initiator is 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone or azobisisobutyronitrile, and the blue light initiator is camphorquinone, 1-phenyl-1,2-propanedione or 4-(dimethylamino)ethyl benzoate.

[0028] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, the shear rate in step (1) is 4000-15000 r / min; the shear rate in step (3) is 4000-15000 r / min; and the photo-crosslinking in step (4) refers to exposing the emulsion E3 to a light source capable of initiating photo-polymerization of the intermediate phase c for 3-20 min.

[0029] The simple preparation method of the solid microcapsule with high encapsulation efficiency as described above, the light source is an ultraviolet high-pressure mercury lamp with a power of 250 W and a center wavelength at 365 nm, or a blue light LED lamp with a power of 200 W and a center wavelength at 425 nm.

[0030] The principle of the present application is as follows:

[0031] The method of the present application uses the shell material phase as an intermediate phase, disperses the core material phase to obtain sufficient interface area, uses interfacial tension to drive spontaneous diffusion to the interface formed, forms a thermodynamically stable core-shell encapsulation configuration, then crosslinks the intermediate phase by light irradiation to complete encapsulation, and the microcapsules obtained have a high encapsulation efficiency, with an encapsulation efficiency of more than 95%. The encapsulation efficiency is calculated by the ratio of the actual core material encapsulation rate to the theoretical core material encapsulation rate. The actual encapsulation rate is the measured core material content in the microcapsules / the amount of core material. The theoretical encapsulation rate is the mass of core material / (the mass of core material+the mass of shell material).

[0032] The method of the present application allows the production of controllable size, in particular less than 20 μm, of a population of double emulsion droplets on an industrial scale. The size control of the capsules obtained by the method of the present application is achieved by controlling the size of the dispersed droplets, which is changed by the input shear force. The greater the shear force received by the droplets, the greater the surface tension is insufficient to maintain the original state of the droplets, and the larger droplets will be split into small droplets, thereby reducing the size of the droplets.

[0033] Advantages:

[0034] (1) The reaction system of the present application is simple, the equipment requirement is low, the process operation is simple and fast, the cost is low, and it is suitable for industrialized batch production;

[0035] (2) The method of the present application has high encapsulation efficiency, regular morphology, and dense and smooth surface of the microcapsules prepared;

[0036] (3) The method of the present application is easy to realize the control of particle size and shell thickness;

[0037] (4) The method of the present application uses the reconstruction of the three-phase emulsion, and under the driving of the interfacial tension in the emulsion, a core-shell encapsulation configuration is formed, with a clear boundary and structure. BRIEF DESCRIPTION OF DRAWINGS

[0038] Fig. 1 A polarizing microscope (POM) image of a solid microcapsule with high encapsulation efficiency prepared in Example 1 of the present application;

[0039] Fig. 2 A scanning electron microscope (SEM) image of a solid microcapsule with high encapsulation efficiency prepared in Example 1 of the present application under different magnifications; the left image has a magnification of 500 times, and the right image has a magnification of 4500 times;

[0040] Fig. 3 A differential scanning calorimeter (DSC) curve of a solid microcapsule with high encapsulation efficiency prepared in Example 1 of the present application;

[0041] Fig. 4Thermogravimetric (TGA) curve of a solid microcapsule with high encapsulation efficiency prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0042] The present application will be further described in conjunction with specific embodiments. It should be understood, however, that these embodiments are intended to illustrate the present application and are not intended to limit the scope of the present application. Moreover, it should be understood that various modifications and changes can be made to the present application by those skilled in the art upon reading the contents of the present application, and such equivalent forms are also within the scope of the appended claims.

[0043] The test methods and equipment involved in the examples are as follows:

[0044] (1) A FLEX300 scanning electron microscope is used to observe the surface morphology of the dried and gold-sprayed solid microcapsule;

[0045] (2) A differential scanning calorimeter (DSC) of American Perkin is used to test the heat storage performance of the solid microcapsule. Under the protection of nitrogen, the temperature is raised from 0°C to 70°C at a rate of 5°C / min, and then cooled to 0°C after holding for 3 min. The DSC curve during the test is recorded, and the phase transition temperature and latent heat value of the solid microcapsule are calculated and obtained;

[0046] (3) A thermal gravimetric analyzer (TGA8000) of American Perkin is used to test the thermal stability performance of the solid microcapsule. Under the protection of nitrogen, the temperature is raised from 50°C to 800°C at a rate of 10°C / min, and the TGA curve during the test is recorded. The core material content in the solid microcapsule is calculated.

[0047] Example 1

[0048] A simple preparation method of a solid microcapsule with high encapsulation efficiency, the specific steps are as follows:

[0049] (1) Preparation of raw materials;

[0050] Core phase a: n-octadecane;

[0051] Continuous phase b: 5wt% PVA aqueous solution, the number average molecular weight of PVA is 20000g / mol;

[0052] Intermediate phase c: composed of polyethylene glycol diacrylate and 2-hydroxy-2-methyl-1-phenyl-1-propanone, the mass content of polyethylene glycol diacrylate in the intermediate phase c is 98%, and the mass content of 2-hydroxy-2-methyl-1-phenyl-1-propanone is 2%;

[0053] (2) The core phase a at 60°C is added to the continuous phase b at 60°C to pre-disperse into a continuous phase emulsion containing core phase droplets at a shear rate of 6000 r / min, denoted as emulsion E1; wherein the volume ratio of the core phase a to the continuous phase b is 1:6;

[0054] (3) The intermediate phase c at 60°C is added to the emulsion E1 at 60°C to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core phase a to the intermediate phase c is 10:3;

[0055] (4) The emulsion E2 is subjected to high-speed shear dispersion at a shear rate of 10000 r / min to obtain a double emulsion containing droplets with controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0056] (5) The emulsion E3 is exposed to a UV high-pressure mercury lamp with a power of 250 W and a center wavelength at 365 nm for irradiation for 20 min for photocrosslinking curing, and then subjected to water washing, filtration and drying to obtain solid microcapsules;

[0057] As shown in Figs. 1-4 , the prepared solid microcapsules have a smooth surface, a core-shell structure, a spherical morphology, a phase change latent heat value of 170 J / g, excellent heat storage performance, an average diameter of 5.23 μm, a solid microcapsule core material content of 69%, and an encapsulation efficiency of 99%.

[0058] Example 2

[0059] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0060] (1) Preparation of raw materials;

[0061] Core phase a: n-octadecane;

[0062] Continuous phase b: PVA aqueous solution with a concentration of 3 wt%, and the number average molecular weight of PVA is 20000 g / mol;

[0063] Intermediate phase c: composed of 1,6-hexanediol diacrylate, 2-hydroxy-2-methyl-1-phenyl-1-propanone and Span-80, the mass content of 1,6-hexanediol diacrylate in the intermediate phase c is 97%, the mass content of 2-hydroxy-2-methyl-1-phenyl-1-propanone is 2%, and the mass content of Span-80 is 1%;

[0064] (2) The core phase a at 60°C is added to the continuous phase b at 60°C to pre-disperse into a continuous phase emulsion containing core phase droplets at a shear rate of 6000 r / min, denoted as emulsion E1; wherein the volume ratio of the core phase a to the continuous phase b is 1:6;

[0065] (3) adding the intermediate phase c with a temperature of 60℃ into the emulsion E1 with a temperature of 60℃ to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core phase a and the intermediate phase c is 10:3;

[0066] (4) high-speed shearing dispersion of the emulsion E2 at a shearing rate of 10000 r / min to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0067] (5) exposing the emulsion E3 to a UV high-pressure mercury lamp with a power of 250W and a center wavelength at 365nm for irradiation for 20min to perform photocrosslinking curing, and then washing with water, filtering and drying to obtain solid microcapsules;

[0068] The prepared solid microcapsules have a smooth surface, a phase change latent heat value of 173.4 J / g, an average diameter of 5.31 μm, and an encapsulation efficiency of 98.3%.

[0069] Example 3

[0070] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0071] (1) preparation of raw materials;

[0072] core phase a: n-octadecane;

[0073] continuous phase b: PVA aqueous solution with a concentration of 5wt%, and the number average molecular weight of PVA is 20000 g / mol;

[0074] intermediate phase c: composed of polyethylene glycol diacrylate and 2-hydroxy-2-methyl-1-phenyl-1-propanone, the mass content of polyethylene glycol diacrylate in the intermediate phase c is 98%, and the mass content of 2-hydroxy-2-methyl-1-phenyl-1-propanone is 2%;

[0075] (2) adding the core phase a with a temperature of 60℃ into the continuous phase b with a temperature of 60℃ to pre-disperse into a continuous phase emulsion containing core phase droplets at a shearing rate of 6000 r / min, denoted as emulsion E1; wherein the volume ratio of the core phase a and the continuous phase b is 1:6;

[0076] (3) adding the intermediate phase c with a temperature of 60℃ into the emulsion E1 with a temperature of 60℃ to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core phase a and the intermediate phase c is 10:3;

[0077] (4) high-speed shearing dispersion of the emulsion E2 at a shearing rate of 6000 r / min to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0078] (5) exposing the emulsion E3 to a light source of a UV high-pressure mercury lamp with a power of 250 W and a center wavelength at 365 nm, irradiating for 20 min, performing photo-crosslinking curing, and then obtaining the solid microcapsules after washing with water, filtering, and drying;

[0079] The prepared solid microcapsules have a smooth surface, a latent heat of phase transition of 169.5 J / g, an average diameter of 7.37 μm, and an encapsulation efficiency of 98.7%.

[0080] Example 4

[0081] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0082] (1) Preparation of raw materials;

[0083] Core phase a: n-octadecane;

[0084] Continuous phase b: a PVA aqueous solution with a concentration of 5 wt%, and the number average molecular weight of PVA is 20000 g / mol;

[0085] Intermediate phase c: composed of polyethylene glycol diacrylate and 2-hydroxy-2-methyl-1-phenyl-1-propanone, the mass content of polyethylene glycol diacrylate in the intermediate phase c is 98%, and the mass content of 2-hydroxy-2-methyl-1-phenyl-1-propanone is 2%;

[0086] (2) The core phase a with a temperature of 60℃ is added to the continuous phase b with a temperature of 60℃, and pre-dispersed into a continuous phase emulsion containing core phase droplets at a shear rate of 6000 r / min, denoted as emulsion E1; wherein the volume ratio of the core phase a to the continuous phase b is 1:6;

[0087] (3) The intermediate phase c with a temperature of 60℃ is added to the emulsion E1 with a temperature of 60℃, to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core phase a to the intermediate phase c is 10:3;

[0088] (4) The emulsion E2 is subjected to high-speed shear dispersion at a shear rate of 14000 r / min, to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0089] (5) exposing the emulsion E3 to a light source of a UV high-pressure mercury lamp with a power of 250 W and a center wavelength at 365 nm, irradiating for 20 min, performing photo-crosslinking curing, and then obtaining the solid microcapsules after washing with water, filtering, and drying;

[0090] The prepared solid microcapsules have a smooth surface, a latent heat of phase transition of 169.5 J / g, an average diameter of 7.37 μm, and an encapsulation efficiency of 98.7%.

[0091] Example 5

[0092] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0093] (1) Preparation of raw materials;

[0094] Core phase a: n-octadecane;

[0095] Continuous phase b: 2wt% PVA aqueous solution, the number average molecular weight of PVA is 20000g / mol;

[0096] Intermediate phase c: composed of 1,6-hexanediol diacrylate, 2-hydroxy-2-methyl-1-phenyl-1-propanone and Span-80, the mass content of 1,6-hexanediol diacrylate in the intermediate phase c is 97%, the mass content of 2-hydroxy-2-methyl-1-phenyl-1-propanone is 2%, and the mass content of Span-80 is 1%;

[0097] (2) The core phase a with a temperature of 60℃ is added to the continuous phase b with a temperature of 60℃, and pre-dispersed into a continuous phase emulsion containing core phase droplets at a shear rate of 6000r / min, denoted as emulsion E1; wherein the volume ratio of core phase a to continuous phase b is 1:6;

[0098] (3) The intermediate phase c with a temperature of 60℃ is added to the emulsion E1 with a temperature of 60℃, to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of core phase a to intermediate phase c is 10:5;

[0099] (4) The emulsion E2 is subjected to high-speed shear dispersion at a shear rate of 10000r / min, to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0100] (5) The emulsion E3 is exposed to an ultraviolet high-pressure mercury lamp with a power of 250W and a center wavelength at 365nm, and irradiated for 20min, to perform photocrosslinking curing, and then washed with water, filtered and dried to obtain solid microcapsules;

[0101] The prepared solid microcapsules have a smooth surface, a phase change latent heat value of 145.6J / g, an average diameter of 4.9μm, and an encapsulation efficiency of 98%.

[0102] Example 6

[0103] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0104] (1) Preparation of raw materials;

[0105] Core phase a: n-octadecane;

[0106] Continuous phase b: PVA aqueous solution with a concentration of 5wt%, the number average molecular weight of PVA is 20000g / mol;

[0107] Intermediate phase c: composed of polyethylene glycol diacrylate and camphorquinone, the mass content of polyethylene glycol diacrylate in the intermediate phase c is 99%, and the mass content of camphorquinone is 1%;

[0108] (2) The core material phase a with a temperature of 60℃ is added to the continuous phase b with a temperature of 60℃, and pre-dispersed into a continuous phase emulsion containing core material phase droplets at a shear rate of 6000r / min, recorded as emulsion E1; wherein the volume ratio of core material phase a to continuous phase b is 1:6;

[0109] (3) The intermediate phase c with a temperature of 60℃ is added to the emulsion E1 with a temperature of 60℃, to obtain a double emulsion, recorded as emulsion E2; wherein the volume ratio of core material phase a to intermediate phase c is 10:7;

[0110] (4) The emulsion E2 is subjected to high-speed shear dispersion at a shear rate of 10000r / min, to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, recorded as emulsion E3;

[0111] (5) The emulsion E3 is exposed to a blue light LED lamp with a power of 200W and a center wavelength at 425nm, irradiated for 20min, and subjected to photo-crosslinking curing, and then washed with water, filtered and dried to obtain solid microcapsules;

[0112] The prepared solid microcapsules have a smooth surface, a phase change latent heat value of 117.7J / g, an average diameter of 4.29μm, and an encapsulation efficiency of 96%.

[0113] Example 7

[0114] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0115] (1) Preparation of raw materials;

[0116] Core material phase a: n-eicosane;

[0117] Continuous phase b: PVA aqueous solution with a concentration of 2wt%, the number average molecular weight of PVA is 20000g / mol;

[0118] Intermediate phase c: composed of 1,4-butanediol diacrylate, 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, Span-80 and pentaerythritol tetraacrylate, the mass content of 1,4-butanediol diacrylate in the intermediate phase c is 74.5%, the mass content of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide is 0.5%, the mass content of Span-80 is 20%, and the mass content of pentaerythritol tetraacrylate is 5wt%;

[0119] (2) The core material phase a with a temperature of 50°C is added to the continuous phase b with a temperature of 50°C, and pre-dispersed into a continuous phase emulsion containing core material phase droplets at a shear rate of 4000r / min, denoted as emulsion E1; wherein the volume ratio of the core material phase a to the continuous phase b is 1:6;

[0120] (3) The intermediate phase c with a temperature of 50°C is added to the emulsion E1 with a temperature of 50°C, to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core material phase a to the intermediate phase c is 10:5;

[0121] (4) The emulsion E2 is subjected to high-speed shear dispersion at a shear rate of 4000r / min, to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0122] (5) The emulsion E3 is exposed to a UV high-pressure mercury lamp with a power of 250W and a center wavelength at 365nm, and irradiated for 3min, to perform photocrosslinking curing, and then washed with water, filtered and dried to obtain solid microcapsules;

[0123] The prepared solid microcapsules have a smooth surface, a phase change latent heat value of 148J / g, an average diameter of 8.6μm, and an encapsulation efficiency of 95%.

[0124] Example 8

[0125] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0126] (1) Preparation of raw materials;

[0127] Core material phase a: n-eicosane;

[0128] Continuous phase b: PVA aqueous solution with a concentration of 2wt%, and the number average molecular weight of PVA is 17000g / mol;

[0129] Intermediate phase c: composed of 1,4-butanediol diacrylate, azobisisobutyronitrile, Span-80 and pentaerythritol tetraacrylate, the mass content of 1,4-butanediol diacrylate in the intermediate phase c is 77%, the mass content of azobisisobutyronitrile is 1%, the mass content of Span-80 is 2%, and the mass content of pentaerythritol tetraacrylate is 20wt%;

[0130] (2) The core material phase a at a temperature of 30°C is added to the continuous phase b at a temperature of 30°C to be pre-dispersed into a continuous phase emulsion containing core material phase droplets at a shear rate of 6000 r / min, denoted as emulsion E1; wherein the volume ratio of the core material phase a to the continuous phase b is 1:6;

[0131] (3) The intermediate phase c at a temperature of 50°C is added to the emulsion E1 at a temperature of 50°C to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core material phase a to the intermediate phase c is 10:5;

[0132] (4) The emulsion E2 is subjected to high-speed shear dispersion at a shear rate of 6000 r / min to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0133] (5) The emulsion E3 is exposed to a blue light LED lamp with a power of 200W and a center wavelength at 425nm for irradiation for 5min to perform photocrosslinking curing, and then the solid microcapsules are obtained after water washing, filtration and drying;

[0134] The prepared solid microcapsules have a smooth surface, a phase change latent heat value of 154.4 J / g, an average diameter of 6.9 μm, and an encapsulation efficiency of 99%.

[0135] Example 9

[0136] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0137] (1) Preparation of raw materials;

[0138] Core material phase a: n-eicosane;

[0139] Continuous phase b: a PVA aqueous solution with a concentration of 2wt%, and the number average molecular weight of PVA is 25000 g / mol;

[0140] Intermediate phase c: composed of 1,4-butanediol diacrylate, 1-phenyl-1,2-propanedione, Span-80 and pentaerythritol tetraacrylate, the mass content of 1,4-butanediol diacrylate in the intermediate phase c is 91%, the mass content of 1-phenyl-1,2-propanedione is 2%, the mass content of Span-80 is 5%, and the mass content of pentaerythritol tetraacrylate is 2wt%;

[0141] (2) The core phase a at a temperature of 40°C is added to the continuous phase b at a temperature of 40°C to pre-disperse into a continuous phase emulsion containing core phase droplets at a shear rate of 8000 r / min, denoted as emulsion E1; wherein the volume ratio of the core phase a to the continuous phase b is 1:6;

[0142] (3) The intermediate phase c at a temperature of 60°C is added to the emulsion E1 at a temperature of 60°C to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core phase a to the intermediate phase c is 10:5;

[0143] (4) The emulsion E2 is subjected to high-speed shear dispersion at a shear rate of 8000 r / min to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0144] (5) The emulsion E3 is exposed to a blue light LED lamp with a power of 200 W and a central wavelength at 425 nm for irradiation for 7 min for photocrosslinking curing, and then subjected to water washing, filtration and drying to obtain solid microcapsules;

[0145] The prepared solid microcapsules have a smooth surface, a phase change latent heat value of 151.5 J / g, an average diameter of 6.1 μm, and an encapsulation efficiency of 97%.

[0146] Example 10

[0147] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0148] (1) Preparation of raw materials;

[0149] Core phase a: n-eicosane;

[0150] Continuous phase b: PVA aqueous solution with a concentration of 5 wt%, and the number average molecular weight of PVA is 20000 g / mol;

[0151] Intermediate phase c: composed of pentanediol diacrylate and 4-(dimethylamino) benzoic acid ethyl ester, the mass content of pentanediol diacrylate in the intermediate phase c is 96%, and the mass content of 4-(dimethylamino) benzoic acid ethyl ester is 4%;

[0152] (2) The core phase a at a temperature of 60°C is added to the continuous phase b at a temperature of 60°C to pre-disperse into a continuous phase emulsion containing core phase droplets at a shear rate of 9000 r / min, denoted as emulsion E1; wherein the volume ratio of the core phase a to the continuous phase b is 1:12;

[0153] (3) The intermediate phase c at a temperature of 60°C is added to the emulsion E1 at a temperature of 60°C to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core phase a to the intermediate phase c is 10:7;

[0154] (4) with the shearing rate of 9000 r / min, the emulsion E2 was subjected to high-speed shearing dispersion to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0155] (5) the emulsion E3 was exposed to a blue light LED lamp with a power of 200 W and a central wavelength at 425 nm for 10 min of irradiation for photocrosslinking curing, and then the solid microcapsules were obtained after water washing, filtration and drying;

[0156] The prepared solid microcapsules have a smooth surface, a latent heat of phase transition of 130.4 J / g, an average diameter of 5.5 μm, and an encapsulation efficiency of 97%.

[0157] Example 11

[0158] A simple preparation method of solid microcapsules with high encapsulation efficiency, the specific steps are as follows:

[0159] (1) preparation of raw materials;

[0160] core material phase a: n-eicosane;

[0161] continuous phase b: a PVA aqueous solution with a concentration of 5 wt%, and the number average molecular weight of PVA is 20000 g / mol;

[0162] intermediate phase c: composed of pentanediol diacrylate and 4-(dimethylamino)ethyl benzoate, the mass content of pentanediol diacrylate in the intermediate phase c is 95%, and the mass content of 4-(dimethylamino)ethyl benzoate is 5%;

[0163] (2) the core material phase a with a temperature of 70 ℃ was added to the continuous phase b with a temperature of 70 ℃, and pre-dispersed into a continuous phase emulsion containing core material phase droplets with a shearing rate of 12000 r / min, denoted as emulsion E1; wherein the volume ratio of the core material phase a to the continuous phase b is 1:18;

[0164] (3) the intermediate phase c with a temperature of 60 ℃ was added to the emulsion E1 with a temperature of 60 ℃ to obtain a double emulsion, denoted as emulsion E2; wherein the volume ratio of the core material phase a to the intermediate phase c is 10:9;

[0165] (4) with the shearing rate of 14000 r / min, the emulsion E2 was subjected to high-speed shearing dispersion to obtain a double emulsion containing droplets of controllable size dispersed in the continuous phase b, denoted as emulsion E3;

[0166] (5) the emulsion E3 was exposed to a blue light LED lamp with a power of 200 W and a central wavelength at 425 nm for 18 min of irradiation for photocrosslinking curing, and then the solid microcapsules were obtained after water washing, filtration and drying;

[0167] The prepared solid microcapsules have smooth surface, latent heat of phase transition value of 117 J / g, average diameter of 2.1 μm, and encapsulation efficiency of 99%.

Claims

1. A simple method for the preparation of solid microcapsules with high encapsulation efficiency, characterized in that, The method comprises the following steps: (1) adding core phase a into continuous phase b, and pre-dispersing into a continuous phase emulsion containing core phase droplets at a certain shear rate, denoted as emulsion E1; (2) adding intermediate phase c into emulsion E1 to obtain a double emulsion, denoted as emulsion E2; (3) performing high-speed shear dispersion on emulsion E2 to obtain a double emulsion containing droplets with controllable size dispersed in continuous phase b, denoted as emulsion E3; (4) performing photo-crosslinking solidification on emulsion E3, and then performing water washing, filtration and drying to obtain solid microcapsules; The core phase a in step (1) and the continuous phase b, and the intermediate phase c in step (2) are mutually immiscible; The intermediate phase c comprises a photo-crosslinkable shell material monomer or a photo-crosslinkable polymer; The sum of the interfacial tension of the intermediate phase c and the core phase a and the continuous phase b is less than the interfacial tension of the core phase a and the continuous phase b; The shear rate in step (1) is 4000-15000 r / min; the shear rate in step (3) is 4000-15000 r / min; The average diameter of the solid microcapsules is 1-20 μm, and the encapsulation efficiency of the solid microcapsules is more than 95%.

2. A simple method for preparing solid microcapsules with high encapsulation efficiency according to claim 1, characterized in that, In step (1), the temperature of the core phase a is 0-100℃, and the temperature of the continuous phase b is 0-100℃; in step (2), the temperature of the intermediate phase c is 20-60℃, and the temperature of the emulsion E1 is 20-60℃.

3. A simple method for preparing solid microcapsules with high encapsulation efficiency according to claim 1, characterized in that, The core phase a is an active material liquid or a solution containing an active material in a dissolved form; The continuous phase b comprises at least one branched polymer, and the number average molecular weight of the branched polymer is greater than 5000 g / mol; The intermediate phase c further comprises an initiator.

4. The simple preparation method of the solid microcapsule with high encapsulation efficiency according to claim 3, characterized in that, The intermediate phase c further comprises a surfactant and a crosslinking agent.

5. The simple preparation method of the solid microcapsule with high encapsulation efficiency according to claim 3 or 4, characterized in that, The viscosity of the continuous phase b is higher than that of the core phase a; the viscosity of the intermediate phase c is higher than that of the core phase a.

6. The simple method for preparing solid microcapsules with high encapsulation efficiency according to claim 5, characterized in that, The volume ratio of the core phase a to the continuous phase b is 1:5-20; the volume ratio of the intermediate phase c to the core phase a is between 1:10 and 10:

1.

7. The simple method for preparing solid microcapsules with high encapsulation efficiency according to claim 4, characterized in that, The mass content of the photo-crosslinkable shell material monomer or the photo-crosslinkable polymer in the intermediate phase c is 55-99%, the mass content of the initiator is 0.5-5%, the mass content of the surfactant is 0-20%, and the mass content of the crosslinking agent is 0-20 wt%.

8. The simple method for preparing solid microcapsules with high encapsulation efficiency according to claim 7, characterized in that, The photo-crosslinkable shell material monomer is a monomer having a reactive functional group, the photo-crosslinkable polymer is a polyether, polyurethane, polyester, polyethylene glycol, polypropylene glycol, polyimide, polyamide, polyolefin, polydimethylsiloxane, polyacetal, polyurea or polysulfide having a reactive functional group, the reactive functional group refers to one or more of the reactive functional groups contained in acrylic ester, methacrylic ester, vinyl ether, N-vinyl ether, mercapto ester, thio olefin, siloxane, epoxy, oxetane, urethane, isocyanate and peroxide; the initiator is an ultraviolet light initiator or a blue light initiator, the surfactant is an anionic surfactant, a non-ionic surfactant, an anionic-non-ionic surfactant, an amphoteric surfactant or an anionic cationic mixed surfactant; the crosslinking agent is a compound having two or more functional groups capable of crosslinking the photo-crosslinkable shell material monomer and / or the photo-crosslinkable polymer.

9. The simple method for preparing solid microcapsules with high encapsulation efficiency according to claim 8, characterized in that, The ultraviolet light initiator is 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone or azobisisobutyronitrile, and the blue light initiator is 1-phenyl-1,2-propanedione, camphorquinone or 4-(dimethylamino)ethyl benzoate.

10. The simple method for preparing solid microcapsules with high encapsulation efficiency according to claim 1, characterized in that, The photo-crosslinking in step (4) refers to exposing the emulsion E3 to a light source capable of initiating photo-polymerization of the intermediate phase c for 3-20 min.

11. A simple method for preparing solid microcapsules with high encapsulation efficiency according to claim 10, characterized in that, The light source is an ultraviolet high-pressure mercury lamp with a power of 250 W and a center wavelength at 365 nm, or a blue light LED lamp with a power of 200 W and a center wavelength at 425 nm.

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