Core-loaded initiation system double-layer composite shell microcapsule and preparation method thereof

Abstract

This application provides a core-carrying initiation system with a bilayer composite shell microcapsule and its preparation method. The preparation method includes: stirring water and natural polymer evenly, then adding a mixture of initiator, accelerator, and solubilizer for emulsification to obtain an emulsified mixture; adding acid and solvent to the emulsified mixture under ice bath conditions and continuing stirring to obtain vesicular microspheres with a single layer of natural polymer as the shell; then adding a mixture of resin and crosslinking agent, replacing the nitrogen gas, heating and holding at that temperature, followed by centrifugation, filtration, and washing to obtain the core-carrying initiation system with a bilayer composite shell microcapsule. The inner barrier membrane effectively prevents leakage of the core material, while the outer resin protective shell enhances the mechanical strength and water resistance of the microspheres. The overall encapsulation is tight, balancing structural strength and protective performance, preventing premature initiation during the system's storage period, and ensuring stable and reliable effects in subsequent curing, polymerization, self-healing, and other application processes.

Description

Technical Field

[0001] This application relates to the field of polymer microsphere materials, specifically to a core-carrying initiation system bilayer composite shell microcapsule and its preparation method. Background Technology

[0002] Polymerization-initiating functional microspheres are widely used in structural adhesives, self-healing composite materials, curing coatings and inks, polymer polymerization, and many other fields. Currently, most microspheres on the market only encapsulate a single initiating agent, and generally suffer from high activation energy and defects in coating density.

[0003] Conventional single benzoyl peroxide initiation systems require stringent triggering conditions and cannot efficiently initiate polymerization reactions at low temperatures, limiting their applicability. Furthermore, existing microsphere shell structures are simple and lack sufficient encapsulation density, allowing internal initiating components to easily leak out, resulting in rapid activity loss during storage and premature failure, severely impacting practical performance. Current technologies lack synergistic composite initiation systems and struggle to achieve tight encapsulation of the reagents, failing to simultaneously meet industry demands for low-temperature controllable initiation and long-term stable storage. To address these shortcomings, this invention develops bilayer composite shell microspheres with a highly sealed encapsulation structure, incorporating a redox composite initiation system, and a preparation method thereof.

[0004] To address the issues of poor density and premature leakage leading to pre-curing of BPO in anaerobic adhesive systems, existing patents, such as CN107213859A, disclose a method for preparing BPO microcapsules. This method uses interfacial polymerization to encapsulate BPO with polyurethane as the capsule wall, achieving sustained release and isolation of the core material. However, the capsule wall's resistance to polar solvents is insufficient, leading to leakage and failure during long-term storage in adhesives containing ester-based media. CN102686208A discloses a BPO microcapsule with a natural polymer as the capsule wall, achieved through sodium alginate crosslinking. However, its capsule wall has low mechanical strength and is prone to premature rupture during use. Most existing BPO microcapsules have a single-layer capsule wall structure, failing to simultaneously achieve core material isolation stability, media resistance, and controllable rupture performance. This makes it difficult to meet the diverse application needs of polymer polymerization initiation, self-healing materials, curing adhesives, and coating / ink systems across various scenarios. Summary of the Invention

[0005] To address one of the shortcomings in the existing technology, the purpose of this application is to provide a core-carrying initiation system bilayer composite shell microcapsule and its preparation method.

[0006] According to a first aspect of this application, a method for preparing a core-carrying initiation system bilayer composite shell microcapsule is provided, comprising: After mixing water and natural polymers evenly, a mixture of initiator, accelerator and solubilizer is added and emulsified to obtain an emulsified mixture; Acid and solvent were added to the emulsion mixture under ice bath conditions, and stirring was continued to obtain vesicular microspheres with a single layer of natural polymer as the shell. A mixture of resin and crosslinking agent is then added, nitrogen is purged, the temperature is raised and maintained, and after centrifugation, filtration, and washing, a bilayer composite shell microcapsule of the core-carrying initiation system is obtained.

[0007] This application uses initiators, accelerators, and solubilizers as core materials. First, a natural polymer inner barrier film is coated onto the surface. Then, an outer resin protective shell is formed through in-situ polymerization and curing, resulting in a double-shell microcapsule with an inner natural polymer and an outer resin. In the second step of this application, the vesicle microspheres refer to microcapsules with a core-shell structure, serving as the precursor for the final preparation of the core-carried initiation system double-shell composite microcapsule. This application overcomes the shortcomings of single natural polymer or traditional single-layer resin-coated BPO microspheres, such as easy leakage, poor media resistance, and premature rupture. The microsphere wall adopts a composite double-layer structure of natural polymer and resin, employing a functional layered design: the inner layer, with its stable polymer chain configuration, encapsulates the core material, effectively preventing leakage and resisting the erosion of polar organic solvents, thus avoiding premature initiation during system storage; the outer layer, with its dense cross-linked resin structure, significantly improves the mechanical strength and water resistance of the microspheres, preventing leakage of internal components. The double-shell microcapsules prepared in this application can be widely used in pre-coated threaded anaerobic adhesives, single-component structural adhesives, self-healing composite materials, curing coatings and inks, and polymer polymerization initiation.

[0008] Optionally, after the water and natural polymer are stirred evenly, a mixture of initiator, accelerator and solubilizer is added for emulsification to obtain an emulsified mixture, wherein the natural polymer is any one of gum arabic, gelatin, sodium alginate, hyaluronic acid, gellan gum and pectin.

[0009] Optionally, after the water and natural polymer are stirred evenly, a mixture of initiator, accelerator and solubilizer is added for emulsification to obtain an emulsified mixture, wherein: the initiator is any one or a combination of tert-butyl peroxide benzoate, benzoyl peroxide and cumene hydroperoxide; The accelerator is any one or more of saccharin, N,N-diethylaniline, sodium saccharin, acetylphenylhydrazine, benzoylhydrazine, succinic acid imide, formamide, triphenylphosphine, and ascorbic acid; The solubilizer is any one or more of the following: carboxyl-terminated acrylonitrile butadiene rubber, diethylene glycol dibenzoate, dibutyl phthalate, diethyl phthalate, dioctyl adipate, and dioctyl sebacate.

[0010] Optionally, after the water and natural polymer are stirred evenly, a mixture of initiator, accelerator and solubilizer is added for emulsification to obtain an emulsified mixture, wherein the water and natural polymer have a mixing ratio of 10~25. C. Stir thoroughly; emulsify using a homogenization process at 3000~7000 rpm for 3~10 min.

[0011] Optionally, the addition of acid and solvent to the emulsion mixture under ice bath conditions, followed by continued stirring, yields vesicular microspheres with a single-layer natural polymer shell, wherein: the acid is any one or a combination of hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, citric acid, phosphoric acid, and acetic acid; The solvent is any one or a combination of ethanol, methanol, acetone, isopropanol and tetrahydrofuran.

[0012] Optionally, acid and solvent are added to the emulsion mixture under ice bath conditions, and stirring is continued to obtain vesicular microspheres with a single layer of natural polymer as the shell, wherein the stirring time is 5~10h.

[0013] Optionally, the mixture of resin and crosslinking agent is added, heated after purging nitrogen, and then held at that temperature, wherein: The resin is a commercially available general-purpose resin prepolymer, selected from at least one of melamine resin, urea-formaldehyde resin, polyurethane, phenolic resin and polyurea prepolymer; The crosslinking agent is any one or a combination of ethylene glycol dimethacrylate, phenol, resorcinol, hexamethoxymethyl melamine, bisphenol A, pentaerythritol, trimethylolpropane, glycerol, sorbitol, and 3-piperazinylpropylmethyldimethoxysilane.

[0014] Optionally, the mixture of resin and crosslinking agent is added, and after purging with nitrogen, the temperature is raised and maintained, wherein the temperature is raised to 50-80°C. C, the heat preservation time is 3~10h.

[0015] By replacing the nitrogen gas to purge the oxygen from the system, premature decomposition and failure of the initiator during the high-temperature insulation stage are prevented, and side reactions of the resin prepolymer are avoided.

[0016] Optionally, the amounts of each raw material, by weight, are as follows: water 30.0~150.0 parts, natural polymer 0.1~4.0 parts, acid (calculated as pure acid) 2.0~15.0 parts, resin 5.0~30.0 parts, crosslinking agent 0.1~2.0 parts, solubilizer 3.0~20.0 parts, initiator 2.0~20.0 parts, accelerator 0.8~17.0 parts, and solvent 10.0~20.0 parts.

[0017] This application first uses natural polymers as film-forming substrates to construct a dense inner barrier film on the surface of the core material, and then solidifies the inner barrier film through in-situ polymerization to form a resin outer protective shell, thereby obtaining a core material with an initiator, accelerator and solubilizer in the core, and a double-shell microcapsule with a natural polymer barrier layer inside and a resin reinforcement layer outside, with a particle size of 30-200 μm.

[0018] According to a second aspect of this application, a core-carrying initiation system bilayer composite shell microcapsule is provided, which is prepared using the method described in the first aspect. The microcapsule has a core-shell structure, with an initiator, accelerator, and solubilizer as the core material, and the core material is encapsulated by a bilayer composite shell structure consisting of an inner natural polymer membrane and an outer crosslinked resin shell. This bilayer composite shell microcapsule can be widely used in various scenarios such as pre-coated thread-locking anaerobic adhesives, single-component structural adhesives, self-healing composite material systems, curable coatings and inks, and polymer polymerization initiation, showing broad application prospects.

[0019] This application adopts a natural polymer-resin double-layer composite capsule structure. The inner polymer barrier layer can firmly wrap the core material, effectively blocking the leakage of the core material, while resisting the erosion of polar organic solvents. The outer cross-linked resin protective layer has excellent sealing performance, significantly improving the water resistance of the microspheres. The overall coating is tight, greatly delaying the decline of the activity of internal components and significantly improving storage stability.

[0020] This application can incorporate a composite redox initiation system of benzoyl peroxide and accelerator. Compared with a single initiator, it effectively reduces the activation energy of the reaction, enables low-temperature triggered polymerization, has stronger reaction rate controllability, and is applicable to a wider range of processes and materials.

[0021] In this application, the dual-layer shell has a clear division of functions, and the structural strength and protective performance are both taken into account. It can prevent the core material from failing prematurely due to interference from the external environment, and ensure the stable and reliable effect of subsequent curing, polymerization, self-healing and other application processes.

[0022] The method for preparing a core-carrying initiation system with a bilayer composite shell microcapsule provided in this application uses an initiator, an accelerator, and a solubilizer as the core material. First, a natural polymer inner barrier membrane is coated onto the core material's surface. Then, an outer resin protective shell is formed through in-situ polymerization and curing, resulting in a bilayer composite shell microcapsule with an inner natural polymer and an outer resin. The inner barrier membrane effectively prevents core material leakage, while the outer resin protective shell enhances the microsphere's mechanical strength and water resistance. The overall encapsulation is tight, balancing structural strength and protective performance. This method prevents premature initiation during the system's storage period and ensures stable and reliable performance in subsequent curing, polymerization, and self-healing processes.

[0023] Other technical effects resulting from the additional features will be further illustrated in the corresponding embodiments. Attached Figure Description

[0024] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart illustrating a method for preparing a core-initiated bilayer composite shell microcapsule according to an exemplary embodiment. Detailed Implementation

[0025] The present application will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all fall within the protection scope of the present application. Parts not described in detail in the following embodiments can be implemented using existing technology.

[0026] The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or devices.

[0027] Example 1 A core-carrying initiation system bilayer composite shell microcapsule is prepared from the following raw materials in parts by weight: 40.0 parts water, 1 part gelatin, 2.5 parts hydrochloric acid, 7.0 parts polyurethane resin, 0.1 parts phenol, 3.0 parts dibutyl phthalate, 2.0 parts cumene hydroperoxide, 7.0 parts acetylphenylhydrazine, and 20.0 parts ethanol.

[0028] Reference Figure 1 The preparation steps are as follows: (1) 25 After mixing water and gelatin evenly under C conditions, add a mixture of cumene hydrogen peroxide, acetylphenylhydrazine and dibutyl phthalate, emulsify using a homogenization process at 7000 rpm for 5 minutes, and then transfer to a three-necked flask. (2) Hydrochloric acid and ethanol were added under ice bath conditions, and stirring was continued for 5 hours to obtain vesicle microspheres with a single layer of natural polymer as the shell. (3) Add the mixture of polyurethane resin and phenol, replace the nitrogen gas, and then raise the temperature to 70°C. After incubation at C for 7 hours, centrifugation, filtration, and washing were performed to obtain DHB1 microcapsules with a particle size of 30~40μm.

[0029] Example 2 A core-carrying initiation system bilayer composite shell microcapsule is prepared from the following raw materials in parts by weight: 150.0 parts water, 4.0 parts sodium alginate, 15 parts citric acid, 30.0 parts melamine resin, 0.2 parts pentaerythritol, 4.0 parts diethylene glycol dibenzoate, 5.0 parts benzoyl peroxide, 16.5 parts saccharin, and 15.0 parts methanol.

[0030] Reference Figure 1 The preparation steps are as follows: (1) 15 After mixing water and sodium alginate evenly under C conditions, add a mixture of benzoyl peroxide, saccharin and diethylene glycol dibenzoate, emulsify using a homogenization process at 4000 rpm for 6 minutes, and then transfer to a three-necked flask. (2) Citric acid and methanol were added under ice bath conditions, and stirring was continued for 6 hours to obtain vesicular microspheres with a single layer of natural polymer as the shell. (3) Add the mixture of melamine resin and pentaerythritol, replace the nitrogen gas, and then heat to 50°C. After incubation at C for 6 hours, centrifugation, filtration, and washing were performed to obtain DHB2 microcapsules with a particle size of 180~200μm.

[0031] Example 3 A core-carrying initiation system bilayer composite shell microcapsule is prepared from the following raw materials in parts by weight: 100.0 parts water, 2.0 parts hyaluronic acid, 4.5 parts phosphoric acid, 17.0 parts urea-formaldehyde resin, 1.0 part pentaerythritol, 4.0 parts diethylene glycol dibenzoate, 3.0 parts benzoyl peroxide, 3.0 parts N,N-diethylaniline, and 18.0 parts acetone.

[0032] Reference Figure 1 The preparation steps are as follows: (1) 10 After mixing water and hyaluronic acid evenly under C conditions, add a mixture of benzoyl peroxide, N,N-diethylaniline and diethylene glycol dibenzoate, emulsify using a homogenization process at 4500 rpm for 8 minutes, and then transfer to a three-necked flask. (2) Phosphoric acid and acetone were added under ice bath conditions, and stirring was continued for 5 hours to obtain vesicular microspheres with a single layer of natural polymer as the shell. (3) Add the mixture of urea-formaldehyde resin and pentaerythritol, replace the nitrogen gas, and then raise the temperature to 80°C. After incubation at C for 10 hours, DHB3 microcapsules with a particle size of 100~120μm were obtained after centrifugation, filtration and washing.

[0033] Example 4 A core-carrying initiation system bilayer composite shell microcapsule is prepared from the following raw materials in parts by weight: 30.0 parts water, 1.0 part gum arabic, 2.0 parts citric acid, 13.0 parts polyurea prepolymer, 1.0 part resorcinol, 14.0 parts dioctyl adipate, 3.0 parts cumene hydrogen peroxide, 1.0 part saccharin, and 18.0 parts acetone.

[0034] Reference Figure 1 The preparation steps are as follows: (1) 22 After mixing water and gum arabic evenly under C conditions, add a mixture of cumene hydrogen peroxide, saccharin and dioctyl adipate, and emulsify using a homogenization process at 4500 rpm for 4 minutes. Then transfer to a three-necked flask. (2) Citric acid and acetone were added under ice bath conditions, and stirring was continued for 7 hours to obtain vesicular microspheres with a single layer of natural polymer as the shell. (3) Add the mixture of polyurea prepolymer and resorcinol, replace the nitrogen gas, and then raise the temperature to 65°C. After incubation at C for 8 hours, centrifugation, filtration, and washing were performed to obtain DHB4 microcapsules with a particle size of 70~80μm.

[0035] Example 5 A core-carrying initiation system bilayer composite shell microcapsule is prepared from the following raw materials in parts by weight: 70.0 parts water, 2.5 parts sodium alginate, 4.0 parts p-toluenesulfonic acid, 9.0 parts phenolic resin, 1.1 parts glycerol, 11.0 parts dibutyl phthalate, 3.0 parts benzoyl peroxide, 1.0 part benzoyl hydrazine, and 10.0 parts tetrahydrofuran.

[0036] Reference Figure 1 The preparation steps are as follows: (1) 25 After mixing water and sodium alginate evenly under C conditions, add a mixture of benzoyl peroxide, benzoyl hydrazine and dibutyl phthalate, emulsify using a homogenization process at 7000 rpm for 3 minutes, and then transfer to a three-necked flask. (2) Add p-toluenesulfonic acid and tetrahydrofuran under ice bath conditions, and continue stirring for 7 hours to obtain vesicle microspheres with a single layer of natural polymer as the shell; (3) Add the mixture of phenolic resin and glycerol, replace the nitrogen gas, and then heat to 55°C. After incubation at C for 9 hours, centrifugation, filtration, and washing were performed to obtain DHB5 microcapsules with a particle size of 30~40μm.

[0037] Example 6 A core-carrying initiation system bilayer composite shell microcapsule is prepared from the following raw materials in parts by weight: 65.0 parts water, 4.0 parts gellan gum, 10.0 parts acetic acid, 5.0 parts urea-formaldehyde resin, 1.3 parts sorbitol, 13.5 parts dioctyl sebacate, 7.0 parts benzoyl peroxide, 1.0 part succinic acid imide, and 10.0 parts tetrahydrofuran.

[0038] Reference Figure 1 The preparation steps are as follows: (1) 25 After mixing water and gellan gum evenly under C conditions, add the mixture of benzoyl peroxide, succinic acid imide and dioctyl sebacate, emulsify using a homogenization process at 3000 rpm for 4 minutes, and then transfer to a three-necked flask. (2) Acetic acid and tetrahydrofuran were added under ice bath conditions, and stirring was continued for 6 hours to obtain vesicle microspheres with a single layer of natural polymer as the shell. (3) Add the mixture of urea-formaldehyde resin and sorbitol, replace the nitrogen gas, and then raise the temperature to 65°C. After incubation at C for 7 hours, centrifugation, filtration, and washing were performed to obtain DHB6 microcapsules with a particle size of 80~90μm.

[0039] Example 7 A core-carrying initiation system bilayer composite shell microcapsule is prepared from the following raw materials in parts by weight: 115.0 parts water, 3.0 parts pectin, 2.0 parts hydrochloric acid, 11.0 parts melamine resin, 0.3 parts 3-piperazinylpropylmethyldimethoxysilane, 20.0 parts diethylene glycol dibenzoate, 2.0 parts benzoyl peroxide, 6.0 parts ascorbic acid, and 10.0 parts isopropanol.

[0040] Reference Figure 1 The preparation steps are as follows: (1) 25 After mixing water and pectin evenly under C conditions, add the mixture of benzoyl peroxide, ascorbic acid and diethylene glycol dibenzoate, emulsify using a homogenization process at 5500 rpm for 7 minutes, and then transfer to a three-necked flask. (2) Hydrochloric acid and isopropanol were added under ice bath conditions, and stirring was continued for 10 hours to obtain vesicle microspheres with a single layer of natural polymer as the shell. (3) Add a mixture of melamine resin and 3-piperazinylpropylmethyldimethoxysilane, replace the nitrogen gas, and then heat to 55°C. After incubation at C for 9 hours, centrifugation, filtration, and washing were performed to obtain DHB7 microcapsules with a particle size of 150~160μm.

[0041] Comparative Example 1 A vesicle-free initiation system, eliminating the vesicle coating structure, with the following raw materials: 40.0 parts water, 2.5 parts hydrochloric acid, 5.0 parts dibutyl phthalate, 5.0 parts cumene hydroperoxide, and 5.0 parts acetylphenylhydrazine.

[0042] Preparation steps: Water, hydrochloric acid, dibutyl phthalate, cumene hydroperoxide, and acetylphenylhydrazine were mixed at 30°C. C. Stir the mixture thoroughly to obtain the initiator component DHB8, which does not employ a vesicle structure.

[0043] Comparative Example 2 A single-layer natural polymer shell structure-initiated system of vesicle microspheres is prepared from the following raw materials in parts by weight: 80.0 parts water, 2.0 parts sodium alginate, 4.5 parts citric acid, 4.0 parts diethylene glycol dibenzoate, 5.0 parts benzoyl peroxide, 2.5 parts saccharin, and 15.0 parts methanol.

[0044] Preparation steps: (1) 15 After mixing water and sodium alginate evenly under C conditions, add a mixture of benzoyl peroxide, saccharin and diethylene glycol dibenzoate, emulsify using a homogenization process at 4000 rpm for 6 minutes, and then transfer to a three-necked flask. (2) Citric acid and methanol were added under ice bath conditions, and after stirring for 6 hours, DHB9 with a particle size of 80~100μm was obtained by centrifugation, filtration and washing.

[0045] Comparative Example 3 A single-layer melamine spherical shell structure-initiated system of vesicular microspheres is prepared from the following raw materials in parts by weight: 115.0 parts water, 2.0 parts hydrochloric acid, 11.0 parts melamine resin, 0.3 parts 3-piperazinylpropylmethyldimethoxysilane, 20.0 parts diethylene glycol dibenzoate, 2.0 parts benzoyl peroxide, and 6.0 parts ascorbic acid.

[0046] Preparation steps: (1) 25 Benzoyl peroxide, ascorbic acid and diethylene glycol dibenzoate were mixed under C and then added to water. The mixture was emulsified using a homogenization process at 3500 rpm for 4 min and then transferred to a three-necked flask. (2) After adding hydrochloric acid, add a mixture of melamine resin and 3-piperazinylpropylmethyldimethoxysilane, replace the nitrogen gas, and then raise the temperature to 75°C. After incubation at C for 9 hours, centrifugation, filtration, and washing were performed to obtain DHB10 microspheres with a particle size of 30~70μm.

[0047] Performance tests were conducted on the above embodiments and comparative examples, as detailed below: Particle size and particle size distribution instrument: laser particle size analyzer; Operation: Take 1g of washed and dried microspheres, add 20mL of deionized water, stir and sonicate for 2min, and then test on the instrument to obtain the average particle size, particle size interval ratio and particle size distribution curve; The uniformity of particle size distribution is evaluated by the coefficient of variation (CV), and the calculation formula is CV = (standard deviation / average diameter) × 100%, following the general analysis specifications of the laser particle size testing industry.

[0048] Encapsulation rate testing instruments: high-speed pulverizer, vacuum filtration device, electric vacuum drying oven, and analytical balance with a density of 0.01 g / L; Test procedure: accurately weigh the mass m1 of the dried and intact microspheres, completely crush the microspheres with the pulverizer, add sufficient acetone and repeatedly stir to extract the internal core material, and filter and wash multiple times to remove all the core material; the filter residue is pure microcapsule wall material, which is vacuum dried to constant weight and then weighed to obtain the mass m2 of the wall material; Encapsulation rate calculation: Encapsulation rate = (m1-m2) / m1×100%; The test adopts the industry-standard detection method of microcapsule solvent extraction.

[0049] Initiator activity testing instrument: High-performance liquid chromatography (HPLC); The crushed microsphere powder was fully extracted with acetone to prepare the test liquid sample solution; The content of effective initiator in the extract was quantitatively determined using the external standard method of HPLC; The measured effective initiator content was compared with the theoretical total amount of core material added during microsphere preparation to calculate the percentage of initiator activity retained in the core material; This test uses the industry-standard quantitative liquid chromatography test method for polymer microcapsule core materials.

[0050] Test methods for resistance to dimethyl carbonate immersion for 72 hours and water immersion for 72 hours: quantitative microspheres are sealed and immersed in the corresponding solvent / deionized water at room temperature and left to stand for 72 hours. After filtration and drying, the dissolution of the core material is calculated. The judgment is divided into "no leakage" and "severe leakage". The general immersion evaluation method for the media stability of microcapsules is adopted.

[0051] Room temperature storage stability test method: 25 C. Store in a light-proof, sealed container for extended periods. Periodically monitor for microsphere leakage and activity degradation. Record the longest storage time during which the microspheres remain intact and do not fail. Use the industry-standard method for evaluating long-term storage of foamed microspheres.

[0052] The performance test results are shown in Table 1.

[0053] Table 1. Performance test results of Examples 1-7 and Comparative Examples 1-3 As can be seen from the data in Table 1, compared with Comparative Examples 1-3, the microcapsules of Examples 1-7 of this application using a natural polymer-resin bilayer composite wall structure have high core material encapsulation efficiency and high initiator activity retention rate. The bilayer composite wall structure significantly improves the water resistance and solvent resistance of the microcapsules, giving them excellent long-term storage stability.

[0054] Extensive experimental research has shown that the bilayer composite shell structure initiation system of the vesicle microspheres of this application, with the following mass ratios: water 30.0~150.0 parts, natural polymer 0.1~4.0 parts, acid 2.0~15.0 parts; resin 5.0~30.0 parts, crosslinking agent 0.1~2.0 parts, solubilizer 3.0~20.0 parts; initiator 2.0~20.0 parts; accelerator 0.8~17.0 parts, solvent 10.0~20.0 parts, exhibits synergistic effects among the components within the above-mentioned ratio range, thereby improving the performance of the microcapsules.

[0055] The foregoing has described some specific embodiments of this application. It should be understood that this application is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this application. The above-described preferred features can be used in any combination without conflict.

Claims

1. A method for preparing a core-carrying initiation system bilayer composite shell microcapsule, characterized in that, include: After mixing water and natural polymers evenly, a mixture of initiator, accelerator and solubilizer is added and emulsified to obtain an emulsified mixture; Acid and solvent were added to the emulsion mixture under ice bath conditions, and stirring was continued to obtain vesicular microspheres with a single layer of natural polymer as the shell. A mixture of resin and crosslinking agent is then added, nitrogen is purged, the temperature is raised and maintained, and after centrifugation, filtration, and washing, a bilayer composite shell microcapsule of the core-carrying initiation system is obtained.

2. The method for preparing the core-carrying initiation system bilayer composite shell microcapsules according to claim 1, characterized in that, The process involves mixing water and natural polymers evenly, then adding a mixture of initiator, accelerator, and solubilizer for emulsification to obtain an emulsified mixture. The natural polymer is any one of gum arabic, gelatin, sodium alginate, hyaluronic acid, gellan gum, and pectin.

3. The method for preparing the core-carrying initiation system bilayer composite shell microcapsules according to claim 1, characterized in that, The process involves mixing water and natural polymers evenly, then adding a mixture of initiator, accelerator, and solubilizer for emulsification to obtain an emulsified mixture. The initiator is any one or a combination of tert-butyl peroxide, benzoyl peroxide, and cumene hydroperoxide. The accelerator is any one or more of saccharin, N,N-diethylaniline, sodium saccharin, acetylphenylhydrazine, benzoylhydrazine, succinic acid imide, formamide, triphenylphosphine, and ascorbic acid; The solubilizer is any one or more of the following: carboxyl-terminated acrylonitrile butadiene rubber, diethylene glycol dibenzoate, dibutyl phthalate, diethyl phthalate, dioctyl adipate, and dioctyl sebacate.

4. The method for preparing the core-carrying initiation system bilayer composite shell microcapsule according to claim 1, characterized in that, The process involves mixing water and natural polymers evenly, then adding a mixture of initiator, accelerator, and solubilizer for emulsification to obtain an emulsified mixture, wherein the water and natural polymers are mixed at a concentration of 10-25 kJ / L. C. Stir thoroughly; emulsify using a homogenization process at 3000~7000 rpm for 3~10 min.

5. The method for preparing the core-carrying initiation system bilayer composite shell microcapsule according to claim 1, characterized in that, The process involves adding acid and solvent to the emulsified mixture under ice bath conditions and continuing stirring to obtain vesicular microspheres with a single layer of natural polymer as the shell, wherein: the acid is any one or a combination of hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, citric acid, phosphoric acid, and acetic acid; The solvent is any one or a combination of ethanol, methanol, acetone, isopropanol and tetrahydrofuran.

6. The method for preparing the core-carrying initiation system bilayer composite shell microcapsules according to claim 1, characterized in that, The process involves adding acid and solvent to the emulsified mixture under ice bath conditions and continuing stirring to obtain vesicular microspheres with a single layer of natural polymer as the shell, wherein the stirring time is 5-10 hours.

7. The method for preparing the core-carrying initiation system bilayer composite shell microcapsules according to claim 1, characterized in that, The mixture of resin and crosslinking agent is then added, purged with nitrogen, heated, and held at that temperature, wherein: The resin is selected from at least one of melamine resin, urea-formaldehyde resin, polyurethane, phenolic resin and polyurea prepolymer; The crosslinking agent is any one or a combination of ethylene glycol dimethacrylate, phenol, resorcinol, hexamethoxymethyl melamine, bisphenol A, pentaerythritol, trimethylolpropane, glycerol, sorbitol, and 3-piperazinylpropylmethyldimethoxysilane.

8. The method for preparing the core-carrying initiation system bilayer composite shell microcapsules according to claim 1, characterized in that, The mixture of resin and crosslinking agent is then added, purged with nitrogen, heated, and held at that temperature, wherein the temperature is raised to 50-80°C. C, the heat preservation time is 3~10h.

9. The method for preparing the core-carrying initiation system bilayer composite shell microcapsule according to claim 1, characterized in that, According to the weight parts, the amounts of each raw material are as follows: water 30.0~150.0 parts, natural polymer 0.1~4.0 parts, acid 2.0~15.0 parts, resin 5.0~30.0 parts, crosslinking agent 0.1~2.0 parts, solubilizer 3.0~20.0 parts, initiator 2.0~20.0 parts, accelerator 0.8~17.0 parts, and solvent 10.0~20.0 parts.

10. A core-carrying initiation system with a bilayer composite shell microcapsule, characterized in that, The microcapsules are prepared using the method described in any one of claims 1 to 9. The microcapsules have a core-shell structure, with an initiator, a promoter, and a solubilizer as the core material. The core material is covered by a double-layer composite shell structure consisting of an inner natural polymer membrane and an outer cross-linked resin shell.

Images