Terpolymer-based double-layer functional microcapsule and preparation method thereof

Abstract

The invention belongs to the technical field of microcapsules, and particularly relates to a terpolymer-based double-layer functional microcapsule and a preparation method thereof. The preparation method comprises the following steps: mixing a core material, tetraethyl orthosilicate, a silane coupling agent, a first monomer, a second monomer, a third monomer, a cross-linking agent and an initiator to obtain an oil phase; dissolving an emulsifier and a dispersant in a solvent to obtain a water phase; and mixing the oil phase and the water phase, emulsifying, and sequentially carrying out a first heating reaction and a second heating reaction to obtain the terpolymer-based double-layer functional microcapsule. The double-layer functional microcapsule of the terpolymer prepared by the preparation method disclosed by the invention can realize coating of components such as perfluorohexanone and the like, and the microcapsule has excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of microcapsules, in particular to a double-layer functional microcapsule based on a terpolymer and a preparation method thereof. Background Art

[0002] Microencapsulation technology is an encapsulation technology that encapsulates solid, liquid or gaseous substances. It can protect the core material (the encapsulated substance) from environmental influences and at the same time control the release of the core material. The performance of microcapsules is closely related to the performance of the wall material. Common wall materials include polymer wall materials and inorganic compound wall materials. Organic polymer wall materials have the advantages of good film-forming properties and embedding effects, adjustable release properties and a wide range of applications, but their thermal stability, thermal conductivity and mechanical strength are poor. Inorganic wall materials have excellent thermal stability, chemical stability and mechanical strength, high thermal conductivity, non-toxicity, good biocompatibility, variety and low cost, but their shell materials are brittle, easy to form porous structures, and have poor sealing properties.

[0003] To overcome the shortcomings of both organic and inorganic wall materials, organic and inorganic wall materials can be combined to form organic-inorganic hybrid microcapsule shells. Currently, hybrid microcapsules are often prepared by incorporating inorganic materials into organic wall materials. However, even when the inorganic materials are densely packed onto the microcapsule surface, significant voids remain between the inorganic materials, preventing complete coverage of the polymer shell and further improving the barrier and mechanical properties of the microcapsules. Therefore, the preparation of microcapsules with double-shells has become a new trend in the development of microcapsules with high barrier and mechanical properties.

[0004] Double-shell microcapsules are microcapsules with two shells, each encapsulating the active ingredient. This structure offers improved encapsulation stability and controlled-release properties, making it suitable for a wide range of applications. Double-shell microcapsules typically consist of an inner shell and an outer shell. The inner shell, closest to the active ingredient, encapsulates and protects it, providing a controlled-release mechanism. The outer shell, the outer shell, enhances the stability and mechanical strength of the microcapsule and further protects the interior. Therefore, double-shell microcapsules are a functional and versatile microcapsule structure, providing an excellent solution for the stable encapsulation and controlled-release of active ingredients. During the release of active substances, double-shell microcapsules exhibit a significantly slower release rate than single-shell microcapsules, resulting in better sustained-release performance. Furthermore, compared to single-shell microcapsules, double-shell microcapsules, with the added protection of a second wall material, inherently increase the density of the capsule wall, thereby improving stability, core material retention, and long-lasting properties. While the commonly used melamine resin / urea-formaldehyde resin processes are mature and industrialized, they contain residual formaldehyde, posing environmental and health risks. Natural polymer materials (such as alginate), while environmentally friendly, suffer from low compressive strength due to their porous structure, and their morphology is difficult to control. In contrast, polymethyl methacrylate (PMMA) has become a research hotspot due to its advantages such as formaldehyde-free residues, biocompatibility, and readily available raw materials. However, in terms of the preparation process of double-layer microcapsules, the traditional step-by-step polymerization method results in a complex process and low yields, and the high temperature and high pressure conditions further increase energy costs. Furthermore, the interfacial adhesion between the organic and inorganic components of organic-inorganic hybrid double-layer microcapsules is poor, making them prone to interfacial delamination under repeated thermal expansion / contraction or mechanical stress, potentially affecting the overall mechanical properties and durability of the material. Furthermore, some double-layer phase-change microcapsules have a high polymerization initiation temperature, making them incapable of encapsulating some low-boiling-point functional substances. Therefore, there is a need to develop double-layer microcapsules that can encapsulate a wider range of functional substances and provide a stable bond between the inner and outer layers.

[0005] Perfluorohexanone is a liquid at room temperature, with a heat of evaporation 1 / 25 of that of water and a vapor pressure 25 times that of water. It is a highly effective and environmentally friendly fire extinguishing agent. However, due to its boiling point of only 49°C, its direct use as a fire extinguishing agent is still somewhat limited. Microencapsulation technology can provide a physical barrier for perfluorohexanone, reducing its contact with external environmental factors (such as oxygen and moisture), improving its stability, preventing its decomposition or deterioration, and extending its shelf life. It also facilitates the controlled release of perfluorohexanone, allowing it to precisely exert its fire extinguishing effect rather than releasing large amounts of it instantly, thereby effectively improving fire extinguishing efficiency.

[0006] Probiotics are a general term for active microorganisms that colonize the human or animal intestines and exert beneficial effects on the host. Probiotics are widely used in food, medicine, animal husbandry, textiles and other fields. The application of probiotics in the textile field is mainly reflected in the development of functional textiles. They can be used to produce fabrics with antimicrobial properties, inhibit the growth of harmful microorganisms, reduce odor, and improve wearing comfort and hygiene. However, probiotics are sensitive to external environmental factors such as temperature and humidity, so they can be encapsulated using microencapsulation technology. Microcapsules provide physical protection for probiotics, allowing them to survive and maintain activity under harsh conditions such as high temperature, high humidity, and chemical treatment during the textile processing process. At the same time, they can achieve the slow release of probiotics, prolonging their action time on the fabric and continuously exerting their beneficial effects such as antibacterial properties, thereby improving the performance durability and added value of textiles and meeting consumer demand for high-quality functional textiles.

[0007] Epoxy resins are widely used in anti-corrosion coatings and adhesives due to their strong bonding and corrosion resistance. Microencapsulation of epoxy resins is primarily driven by the following: 1. It effectively improves their stability and extends their shelf life; 2. It allows for controlled curing reactions; 3. It reduces their toxicity and irritation, making them more environmentally friendly and user-friendly; and 4. It improves their compatibility and broadens their application.

[0008] Therefore, the present invention uses a double-shelled structure combining inorganic and organic wall materials to encapsulate a core material, such as perfluorohexanone, probiotics, and epoxy resin, to produce double-shelled functional microcapsules. This extends storage life and facilitates portability, thereby expanding their application and convenience. Furthermore, the double-shelled functional microcapsules can be spun to produce functional fibers and fabrics for applications in outdoor clothing, home textiles, fire-resistant clothing, medical textiles, architectural textiles, and other fields. This not only enhances the performance and added value of textiles, meeting the diverse market and societal demands for textiles, but also promotes industrial upgrading and technological innovation to a certain extent. Summary of the Invention

[0009] In view of this, the present invention provides a double-layer functional microcapsule based on a ternary copolymer and a preparation method thereof to solve the problem that the existing preparation method of the double-layer functional microcapsule cannot meet the coating requirements of core materials such as perfluorohexanone, probiotics, and epoxy resin, as well as the problem that the existing double-layer functional microcapsules have poor performance.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] A method for preparing double-layer functional microcapsules based on a terpolymer comprises the following steps:

[0012] 1) mixing a core material, tetraethyl orthosilicate, a silane coupling agent, a first monomer, a second monomer, a third monomer, a crosslinking agent, and an initiator to obtain an oil phase;

[0013] dissolving an emulsifier and a dispersant in a solvent to obtain an aqueous phase;

[0014] 2) mixing the oil phase and the water phase for emulsification to obtain an emulsion;

[0015] 3) subjecting the emulsion obtained in step 2) to a first heating reaction and a second heating reaction in sequence to obtain double-layer functional microcapsules based on the terpolymer;

[0016] The first monomer includes one or more of methyl methacrylate, n-butyl methacrylate and ethyl methacrylate;

[0017] The second monomer includes one or more of methyl acrylate, n-butyl acrylate and isooctyl acrylate;

[0018] The third monomer includes one or more of methacrylic acid, acrylic acid and itaconic acid.

[0019] Preferably, the mass ratio of the first monomer, the second monomer and the third monomer is 5-8:1-3:1-2.

[0020] Preferably, the mass ratio of the core material, tetraethyl orthosilicate, silane coupling agent, crosslinking agent, initiator and the sum of the first monomer, the second monomer and the third monomer is 6.5-17:2-10:0.2-2.5:0.1-0.4:0.05-0.2:1.

[0021] Preferably, the core material comprises one or more of perfluorohexanone and its related fluorides, probiotics, and epoxy resin;

[0022] The silane coupling agent includes one or more of γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane and allyltrimethoxysilane;

[0023] The cross-linking agent includes one or more of pentaerythritol tetraacrylate, trimethylolpropane triacrylate and ethylene glycol dimethacrylate;

[0024] The initiator includes one or more of ferrous chloride-potassium persulfate, dibenzoyl peroxide-N,N-dimethylaniline and potassium persulfate-sodium bisulfite.

[0025] Preferably, the emulsifier is cetyltrimethylammonium bromide; the dispersant is polyvinylpyrrolidone;

[0026] The solvent is an ethanol aqueous solution.

[0027] Preferably, the mass fraction of hexadecyltrimethylammonium bromide in the aqueous phase is 0.4-2%;

[0028] The mass fraction of the polyvinyl pyrrolidone is 3-7%.

[0029] Preferably, the mass ratio of the oil phase to the water phase in step 2) is 10-21:108-130.

[0030] Preferably, the emulsification rate in step 2) is 3000-12000 rpm, and the emulsification time is 5-10 min.

[0031] Preferably, the temperature of the first heating reaction in step 3) is 30-55° C., and the time is 1.8-3.5 h;

[0032] The first heating reaction process also includes adding alkali solution;

[0033] The mass ratio of the emulsion to the alkali solution is 121-151:0.2-3.1, the mass fraction of the alkali solution is 0.14-2.48%, and the alkali solution is added 20-30 minutes after the start of the first heating reaction;

[0034] The temperature of the second heating reaction is 45-85° C., and the time is 3-5 hours.

[0035] Another object of the present invention is to provide a double-layer functional microcapsule based on a terpolymer prepared by the preparation method.

[0036] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0037] The double-layer functional microcapsules of the present invention utilize an organic-inorganic double shell as their wall material, combining the advantages of both organic and inorganic shells. This improves the mechanical strength and stability of the microcapsules, preventing the shell from cracking and core material leakage that can occur during use in single-layer microcapsules due to environmental influences such as squeezing, abrasion, acid and alkali conditions, and UV exposure. Furthermore, the release rate of the double-layer microcapsules is significantly slower than that of single-layer microcapsules, and the core material exhibits superior sustained-release properties, resulting in a long-lasting effect.

[0038] 2. The inorganic wall material selected in the present invention is silicon dioxide, which is non-toxic, environmentally friendly, has good thermal stability and relatively ideal thermal conductivity, and has the advantages of relatively simple preparation process and easy large-scale production. It is an ideal coating material; the organic wall material is polyacrylate polymer, which has the advantages of safety and non-toxicity, low cost and sufficient supply of raw materials, no formaldehyde residue, safer reaction monomers, wider sources, and easier to control polymerization reactions.

[0039] 3. The polyacrylate polymer of the present invention is a ternary copolymer. The first monomer is reasonably priced and widely used in industry. The second monomer can improve the flexibility, weather resistance and chemical corrosion resistance of the copolymer. The third monomer is a water-soluble carboxylic acid. Copolymerized with the acrylic ester monomer, it can expand the polarity difference between the monomers used to synthesize the capsule wall material and the organic phase material, thereby increasing the driving force for the polymer to precipitate from the organic phase. It can also reduce the surface tension of the system through self-emulsification and promote the stability of the emulsion. By introducing three monomers, the present invention can change the structure of the polyacrylate polymer macromolecule, thereby improving the properties of the polymer, such as glass transition temperature, elasticity, plasticity, softness, mechanical strength, melting point, solubility, surface properties, etc., promote the formation of its core-shell structure, and improve its encapsulation rate. When the core material is perfluorohexanone and its related fluorides, the carboxyl group of the third monomer can form a weak interaction with the fluorocarbon chain of perfluorohexanone through hydrogen bonding. Although it does not directly participate in the reaction, it can optimize the interfacial wettability of the microcapsule and improve its sustained release performance as a fire extinguishing agent at high temperatures. At the same time, the dense shell of the third monomer can reduce its volatilization loss during storage and maintain the rapid vaporization characteristics of the fire extinguishing agent after release.

[0040] 4. In microcapsules with polymer shell materials, an excessively high glass transition temperature improves the microcapsule's compressive strength but increases the risk of brittle fracture. An excessively low glass transition temperature enhances flexibility but can lead to fracture due to excessive deformation or temperature sensitivity. The present invention lowers the polymer's glass transition temperature by introducing a comonomer, triggering chain segment motion at relatively low temperatures and accelerating the release of the functional core material. Simultaneously, through the action of coupling agents and crosslinking agents, a dynamic balance between mechanical strength and release behavior is achieved. This approach utilizes the chain segment mobility of a low glass transition temperature while also increasing the polymer's crosslinking degree to a certain extent through the crosslinking agent, thereby preventing fracture.

[0041] 5. The polyacrylate copolymers of the present invention contain methacrylic acid or acrylic acid monomers, which have dissociable carboxyl groups in their molecular structure. When the surrounding pH changes, the carboxyl groups can gain or lose protons, thereby altering the polymer's charge state and molecular conformation. When the human body sweats after exercise, the pH of the skin changes, allowing the core material inside the microcapsule, such as probiotics, to be released more effectively, providing excellent protection for the skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0043] Figure 1This is a scanning electron microscope image of the double-layer perfluorohexanone fire extinguishing functional microcapsules prepared in Example 1 of the present invention;

[0044] Figure 2 This is a comparison diagram of the flame change process of the flame retardant experiment in Example 1 of the present invention, wherein: Figure 2 (a) is the control group, Figure 2 (b) in the figure is the wall material group. Figure 2 (c) in the figure is the core material group. Figure 2 (d) in the figure is the microcapsule group. DETAILED DESCRIPTION

[0045] The present invention provides a method for preparing double-layer functional microcapsules based on a terpolymer, comprising the following steps:

[0046] 1) mixing a core material, tetraethyl orthosilicate, a silane coupling agent, a first monomer, a second monomer, a third monomer, a crosslinking agent, and an initiator to obtain an oil phase;

[0047] dissolving an emulsifier and a dispersant in a solvent to obtain an aqueous phase;

[0048] 2) mixing the oil phase and the water phase for emulsification to obtain an emulsion;

[0049] 3) subjecting the emulsion obtained in step 2) to a first heating reaction and a second heating reaction in sequence to obtain double-layer functional microcapsules based on the terpolymer.

[0050] In the present invention, the first monomer includes one or more of methyl methacrylate, n-butyl methacrylate and ethyl methacrylate; the second monomer includes one or more of methyl acrylate, n-butyl acrylate and isooctyl acrylate; and the third monomer includes one or more of methacrylic acid, acrylic acid and itaconic acid.

[0051] In the present invention, the mass ratio of the first monomer, the second monomer and the third monomer is 5-8:1-3:1-2, preferably 5.5-7.5:1.5-2.5:1.2-1.8, more preferably 6-7:2:1.4-1.6, and further preferably 6.5:2:1.5.

[0052] In the present invention, the mass ratio of the core material, tetraethyl orthosilicate, silane coupling agent, crosslinking agent, initiator and the sum of the first monomer, the second monomer and the third monomer is 6.5-17:2-10:0.2-2.5:0.1-0.4:0.05-0.2:1, preferably 8-15:4-8:0.5-2:0.2-0.3:0.1-0.18:1, and more preferably 10-12:5-6:1:0.25:0.15:1.

[0053] In the present invention, the core material includes one or more of perfluorohexanone and its related fluorides, probiotics, and epoxy resin.

[0054] In the present invention, when the core material is probiotics, the probiotics refer to probiotics mixed with oily substances, and the oily substances include one or more of coconut oil / soybean oil (7:3m / m), coconut oil / dehydrated castor oil (5:5m / m) and coconut oil / corn oil (6:4m / m). The oily substance can act as a carrier for the probiotics, and at the same time can provide certain nutrients for the probiotics, which is beneficial to prolong the storage time of the probiotics; the types of probiotics include one or more of Bacillus coagulans, Bacillus subtilis, lactic acid bacteria and Bacillus licheniformis.

[0055] In the present invention, the silane coupling agent includes one or more of γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane and allyltrimethoxysilane; the cross-linking agent includes one or more of pentaerythritol tetraacrylate, trimethylolpropane triacrylate and ethylene glycol dimethacrylate; the initiator includes one or more of ferrous chloride-potassium persulfate (the mass ratio of ferrous chloride to potassium persulfate is preferably 1:2-3, more preferably 1:2.1), dibenzoyl peroxide-N,N-dimethylaniline (the mass ratio of dibenzoyl peroxide to N,N-dimethylaniline is preferably 5:1-3, more preferably 5:2) and potassium persulfate-sodium bisulfite (the mass ratio of potassium persulfate to sodium bisulfite is preferably 1.3-2.6:1, more preferably 1.5-2.5:1, and further preferably 2:1).

[0056] In the present invention, the emulsifier is cetyltrimethylammonium bromide; the dispersant is polyvinylpyrrolidone; and the solvent is an ethanol aqueous solution.

[0057] In the present invention, hexadecyltrimethylammonium bromide stabilizes the emulsion through electrostatic repulsion, reduces the oil-water interfacial tension, and promotes the hydrolysis and condensation of tetraethyl orthosilicate at the oil-water interface to form a dense SiO2 shell. Its hydrophobic segments are combined with the hydrophobic core material, and the hydrophilic groups are arranged outward to form a micellar structure, which wraps the core material and optimizes the uniformity of the SiO2 shell. Polyvinylpyrrolidone stabilizes the emulsion through the steric effect, and its long-chain molecules are adsorbed on the surface of the droplets to form a physical barrier to prevent particle aggregation, especially to maintain the stability of the system under high temperature or mechanical stirring; at the same time, the hydrophilic groups (pyrrolidone rings) of polyvinylpyrrolidone form hydrogen bonds with the hydroxyl groups on the SiO2 surface, enhancing the binding force between the shell and the polymethacrylate copolymer layer; and at the same time, polyvinylpyrrolidone acts as a dispersant for the polymerization of the polymethacrylate copolymer monomer, ensuring that the outer layer of the copolymer is evenly coated to form a complete double-shell structure. Combining the two can utilize their electrostatic stabilization and steric hindrance effects to synergistically reduce shell defects (such as pores or cracks), adapt to complex reaction conditions, and improve the mechanical strength and thermal stability of microcapsules.

[0058] In the present invention, the mass fraction of the hexadecyltrimethylammonium bromide is 0.4-2%, specifically 0.5%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, or 1.8%.

[0059] In the present invention, the mass fraction of the polyvinyl pyrrolidone is 3-7%, specifically 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, or 6.5%.

[0060] In the present invention, the mass ratio of the oil phase to the water phase in step 2) is 10-21:108-130, preferably 15-20:110-125, and more preferably 16-18:115-120.

[0061] In the present invention, the emulsification rate in step 2) is 3000-12000 rpm, specifically 4000 rpm, 5000 rpm, 6000 rpm, 8000 rpm, or 10000 rpm; the emulsification time is 5-10 min, specifically 6 min, 7 min, 8 min, or 9 min.

[0062] In the present invention, the temperature of the first heating reaction in step 3) is 30-55°C, specifically 35°C, 40°C, 45°C, or 50°C; the time is 1.8-3.5h, specifically 2h, 2.2h, 2.4h, 2.5h, 2.6h, 2.8h, 3h, 3.2h, or 3.4h.

[0063] In the present invention, the first heating reaction process also includes the addition of alkali solution.

[0064] In the present invention, the mass ratio of the emulsion to the alkali solution is 121-151:0.2-3.1, preferably 125-145:0.5-3, further preferably 130-140:0.8-2.5, further preferably 135:1-2, and most preferably 135:1.5; the mass fraction of the alkali solution is 0.14-2.48%, specifically 0.15%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, and 2.4%; the timing of adding the alkali solution is 20-30 minutes after the start of the first heating reaction, specifically 22 minutes, 24 minutes, 25 minutes, 26 minutes, and 28 minutes.

[0065] In the present invention, the alkali solution includes aqueous ammonia.

[0066] In the present invention, the temperature of the second heating reaction is 45-85°C, specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, and 80°C; the time is 3-5h, specifically 3.2h, 3.5h, 3.8h, 4h, 4.2h, 4.5h, and 4.8h.

[0067] The present invention also provides a double-layer functional microcapsule based on the terpolymer prepared by the preparation method.

[0068] In the present invention, the double-layer functional microcapsules can not only be directly arranged on the surface of textiles, but also be used for spinning to obtain functional fibers and fabrics, which are used in outdoor clothing, home textiles, fire-resistant clothing, medical textiles, architectural textiles and other fields.

[0069] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0070] Example 1

[0071] The preparation process of a double-layer perfluorohexanone fire extinguishing functional microcapsule is as follows:

[0072] (1) 16.75 parts of perfluorohexanone, 6.25 parts of tetraethyl orthosilicate, 1.25 parts of γ-methacryloyloxypropyltrimethoxysilane (accounting for 20% of the mass fraction of tetraethyl orthosilicate), 0.375 parts of pentaerythritol tetraacrylate, 0.05 parts of ferrous chloride-potassium persulfate (mass ratio 1:2.1), and 1 part of monomer (composed of methyl methacrylate, methyl acrylate, and acrylic acid in a mass ratio of 5:2:1) were mixed to form a uniform oil phase.

[0073] (2) The emulsifier cetyltrimethylammonium bromide (CTAB) and the dispersant polyvinylpyrrolidone (PVP) were dissolved in a mixture of ethanol and water to prepare an aqueous phase, wherein the mass fraction of cetyltrimethylammonium bromide was 0.6%, the mass fraction of polyvinylpyrrolidone was 5%, and the volume ratio of ethanol to water was 47.3:23.7.

[0074] (3) The water phase and the oil phase were mixed (oil phase:water phase = 10.27:129.89 m / m) and emulsified in a high shear emulsifier at 4000 rpm for 10 min to form a stable oil-in-water (O / W) emulsion.

[0075] (4) The emulsion was poured into a three-necked flask and placed on a magnetic stirrer. The reaction temperature was adjusted to 40°C, the stirring speed was 300 rpm, and the reaction was carried out for 20 min. Then, 1% ammonia water (ammonia water: emulsion = 1:100 m / m) was slowly added to the flask and the reaction was continued for 2 h.

[0076] (5) The reaction temperature was raised to 45°C, and the reaction was continued for 4 hours before the reaction was terminated to prepare a double-layer perfluorohexanone fire extinguishing function microcapsule. The particle size of the perfluorohexanone microcapsule prepared in Example 1 of the present invention was 13.59 μm, and its scanning electron microscope image was as shown in FIG. Figure 1 As shown by Figure 1 It can be seen that the microcapsules prepared in Example 1 are spherical in shape and the particle size is relatively uniform.

[0077] In order to study the application of microcapsules in fire extinguishing, a small-scale fire extinguishing test was carried out in the laboratory. 2 ml of ethanol was poured into a crucible, and then the wall material (excluding perfluorohexanone, which has the same preparation process as in Example 1), core material (perfluorohexanone) and microcapsules (double-layer perfluorohexanone fire extinguishing function microcapsules prepared in Example 1) were added, respectively, and recorded as the wall material group, core material group and microcapsule group, respectively. An additional control group without adding other components was set up, ethanol was ignited, and the combustion of the crucible was recorded to observe the flame changes and fire extinguishing time. The flame changes and fire extinguishing time are as follows: Figure 2 As shown in Table 1, Figure 2 (a) is the control group, Figure 2 (b) in the figure is the wall material group. Figure 2 (c) in the figure is the core material group. Figure 2 (d) in the figure is a microcapsule group. Figure 2 As shown in Table 1, the addition of wall materials, core materials and other materials to ethanol alone has little effect on the combustion of ethanol, and the flame extinction time decreases slightly. However, after the double-layer functional microcapsules prepared in Example 1 are added to ethanol, the flame becomes smaller at 20 seconds and the flame is extinguished at 40 seconds. The flame extinction time is greatly shortened, indicating that the microcapsules prepared in Example 1 have a good fire extinguishing effect.

[0078] Table 1 Flame extinction time

[0079] sample ethanol Ethanol + wall material Ethanol + core material Ethanol + microcapsules Flame extinguished / s 80 77 68 40

[0080] Comparative Example 1

[0081] The only difference between Comparative Example 1 and Example 1 is that the three monomers are replaced by methyl methacrylate in equal amounts to obtain double-layer perfluorohexanone fire extinguishing microcapsules. The mechanical strength of the microcapsules in Comparative Example 1 is 1.5 MPa.

[0082] The mechanical strength of the double-layer perfluorohexanone fire extinguishing functional microcapsules prepared in Example 1 is 2.4 MPa. Compared with Comparative Example 1, the mechanical strength of the microcapsules is greatly improved, indicating that the molecular structure of the terpolymer is changed by introducing the comonomer and the cross-linking agent, thereby enhancing the mechanical properties of the double-layer wall material.

[0083] Example 2

[0084] (1) 0.54 parts of Bacillus coagulans probiotics, 10.89 parts of coconut oil / dehydrated castor oil (coconut oil: dehydrated castor oil = 5:5 m / m), 6.25 parts of tetraethyl orthosilicate, 1.25 parts of γ-methacryloyloxypropyltrimethoxysilane (accounting for 20% of the mass fraction of tetraethyl orthosilicate), 0.19 parts of pentaerythritol tetraacrylate, 0.1 parts of ferrous chloride-potassium persulfate (mass ratio 1:2.1), and 1 part of monomer (composed of methyl methacrylate, methyl acrylate, and acrylic acid in a mass ratio of 5:2:1) were mixed under ultrasonication to form a uniform oil phase.

[0085] (2) The emulsifier cetyltrimethylammonium bromide (CTAB) and the dispersant polyvinylpyrrolidone (PVP) were dissolved in a mixture of ethanol and water to prepare an aqueous phase, wherein the mass fraction of cetyltrimethylammonium bromide was 0.6%, the mass fraction of polyvinylpyrrolidone was 5%, and the volume ratio of ethanol to water was 82:41.

[0086] (3) The aqueous phase and the oil phase were mixed (oil phase: aqueous phase = 16.17:112.93 m / m) and emulsified in a high shear emulsifier at 12,000 rpm for 5 min to form a stable oil-in-water (O / W) emulsion.

[0087] (4) The emulsion was poured into a three-necked flask and placed on a magnetic stirrer. The reaction temperature was adjusted to 55°C, the stirring speed was 300 rpm, and the reaction was carried out for 25 min. Then, 1% ammonia water (ammonia water: emulsion = 1:100 m / m) was slowly added to the flask and the reaction was continued for 2 h.

[0088] (5) The reaction temperature was raised to 80°C, and the reaction was continued for 4 hours before being terminated to prepare double-layer probiotic functional microcapsules.

[0089] The double-layer probiotic functional microcapsules prepared in this embodiment can be added to the spinning process of fibers such as viscose, modal and lyocell. The double-layer probiotic functional microcapsules prepared in this embodiment are mixed with cellulose pulp to evenly disperse the probiotic microcapsules into the cellulose spinning solution. The spinning solution is extruded through a spinneret to form a thin stream, which is coagulated in a coagulation bath, and then stretched, washed and dried to obtain a probiotic lyocell fiber. The obtained probiotic lyocell fiber was tested for its anti-mite performance, and the mite repellency rate was 77.6%, which has an anti-mite effect. The obtained probiotic lyocell fiber was tested for its antibacterial performance, and the antibacterial rate of Staphylococcus aureus was 97.4%, and the antibacterial rate of Escherichia coli was 93.1%, which has a good antibacterial effect. The method of this embodiment is also applicable to other fabrics, such as underwear, T-shirts, home textiles, medical textiles and other fields.

[0090] Example 3

[0091] (1) 7 parts of bisphenol F epoxy resin, 2.08 parts of tetraethyl orthosilicate, 0.42 parts of γ-methacryloxypropyltrimethoxysilane (accounting for 20% of the mass fraction of tetraethyl orthosilicate), 0.19 parts of pentaerythritol tetraacrylate, 0.1 parts of dibenzoyl peroxide-N,N-dimethylaniline (mass ratio 5:2), and 1 part of monomer (composed of methyl methacrylate, n-butyl acrylate, and methacrylic acid in a mass ratio of 7.5:3:1.5) were mixed to form a uniform oil phase.

[0092] (2) The emulsifier cetyltrimethylammonium bromide (CTAB) and the dispersant polyvinylpyrrolidone (PVP) were dissolved in a mixture of ethanol and water to prepare an aqueous phase, wherein the mass fraction of cetyltrimethylammonium bromide was 0.6%, the mass fraction of polyvinylpyrrolidone was 5%, and the volume ratio of ethanol to water was 82:41.

[0093] (3) The water phase and the oil phase were mixed (oil phase:water phase = 17.8:113.02 m / m) and emulsified in a high shear emulsifier at 8000 rpm for 10 min to form a stable oil-in-water (O / W) emulsion.

[0094] (4) The emulsion was poured into a three-necked flask and placed on a magnetic stirrer. The reaction temperature was adjusted to 55°C, the stirring speed was 300 rpm, and the reaction was carried out for 20 min. Then, ammonia water with a mass concentration of 1% (ammonia water: emulsion = 1:100 m / m) was slowly added to the flask, and the reaction was continued for 2 h.

[0095] (5) The reaction temperature was raised to 80°C, and the reaction was continued for 4 hours before being terminated to prepare a double-layer epoxy resin functional microcapsule. The particle size of the microcapsule prepared in this example was 23.54 μm.

[0096] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0097] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing double-layer functional microcapsules based on terpolymers, characterized in that: The steps include: 1) mixing a core material, tetraethyl orthosilicate, a silane coupling agent, a first monomer, a second monomer, a third monomer, a crosslinking agent, and an initiator to obtain an oil phase; dissolving an emulsifier and a dispersant in a solvent to obtain an aqueous phase; 2) mixing the oil phase and the water phase for emulsification to obtain an emulsion; 3) subjecting the emulsion obtained in step 2) to a first heating reaction and a second heating reaction in sequence to obtain double-layer functional microcapsules based on the terpolymer; The first monomer includes one or more of methyl methacrylate, n-butyl methacrylate and ethyl methacrylate; The second monomer includes one or more of methyl acrylate, n-butyl acrylate and isooctyl acrylate; The third monomer includes one or more of methacrylic acid, acrylic acid and itaconic acid.

2. The method for preparing double-layer functional microcapsules based on terpolymer according to claim 1, characterized in that: The mass ratio of the first monomer, the second monomer and the third monomer is 5-8:1-3:1-2.

3. The method for preparing double-layer functional microcapsules based on terpolymer according to claim 2, characterized in that: The mass ratio of the core material, tetraethyl orthosilicate, silane coupling agent, crosslinking agent, initiator and the sum of the first monomer, the second monomer and the third monomer is 6.5-17:2-10:0.2-2.5:0.1-0.4:0.05-0.2:

1.

4. The method for preparing double-layer functional microcapsules based on terpolymers according to any one of claims 1 to 3, characterized in that: The core material includes one or more of perfluorohexanone and its related fluorides, probiotics, and epoxy resin; The silane coupling agent includes one or more of γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane and allyltrimethoxysilane; The cross-linking agent includes one or more of pentaerythritol tetraacrylate, trimethylolpropane triacrylate and ethylene glycol dimethacrylate; The initiator includes one or more of ferrous chloride-potassium persulfate, dibenzoyl peroxide-N,N-dimethylaniline and potassium persulfate-sodium bisulfite.

5. The method for preparing double-layer functional microcapsules based on terpolymer according to claim 4, characterized in that: The emulsifier is cetyltrimethylammonium bromide; the dispersant is polyvinylpyrrolidone; The solvent is an ethanol aqueous solution.

6. The method for preparing double-layer functional microcapsules based on terpolymer according to claim 5, characterized in that: The mass fraction of hexadecyltrimethylammonium bromide in the aqueous phase is 0.4-2%; The mass fraction of the polyvinyl pyrrolidone is 3-7%.

7. The method for preparing double-layer functional microcapsules based on terpolymer according to claim 5 or 6, characterized in that: The mass ratio of the oil phase to the water phase in step 2) is 10-21:108-130.

8. The method for preparing double-layer functional microcapsules based on terpolymer according to claim 7, characterized in that: The emulsification rate in step 2) is 3000-12000 rpm, and the emulsification time is 5-10 minutes.

9. The method for preparing double-layer functional microcapsules based on terpolymer according to claim 8, characterized in that: In step 3), the temperature of the first heating reaction is 30-55° C. and the time is 1.8-3.5 h; The first heating reaction process also includes adding alkali solution; The mass ratio of the emulsion to the alkali solution is 121-151:0.2-3.1, the mass fraction of the alkali solution is 0.14-2.48%, and the alkali solution is added 20-30 minutes after the start of the first heating reaction; The temperature of the second heating reaction is 45-85° C., and the time is 3-5 hours.

10. Double-layer functional microcapsules based on terpolymers prepared by the preparation method according to any one of claims 1 to 9.

Images