Heat conduction reinforced phase change microcapsule, preparation method thereof and application of microcapsule in preparation of oil-based phase change cooling liquid

Abstract

The invention provides a heat conduction reinforced phase change microcapsule, a preparation method thereof and an application of the microcapsule in preparation of an oil-based phase change cooling liquid. The method comprises the following steps: dissolving an inorganic substance reaction precursor, an organic resin monomer, an oil-soluble heat-conducting filler, a cross-linking agent and an initiator in a molten phase-change material to prepare a dispersed phase; preparing a continuous phase by dispersing an emulsifier and a water-soluble heat-conducting material in a polar solvent; dispersing the dispersed phase into the continuous phase, and emulsifying to obtain microemulsion; the inorganic substance reaction precursor is subjected to an interface reaction, then the organic resin monomer is subjected to a polymerization reaction, and finally the phase change microcapsule is obtained through separation. The phase change microcapsule is further compounded with an oil-based cooling liquid to prepare the oil-based phase change material cooling liquid. The heat conduction reinforced phase change microcapsule prepared by the invention has the characteristics of good temperature control effect, simple preparation process and the like, and can be widely applied to the fields of thermal control of electronic products and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of phase change energy storage materials, and specifically relates to a heat conductivity enhanced phase change microcapsule and a preparation method thereof and an application thereof in the preparation of an oil-based phase change coolant. Background Art

[0002] In recent years, with the rapid development of the electronics and semiconductor industries, electronic components have shown a trend of high integration. In order to solve the mismatch in time and space between high-power electronic components in a small space, advanced thermal management materials with good thermal conductivity and temperature control capabilities are in urgent need of development. Phase change materials are a type of material that can absorb or release energy from the outside in the form of latent heat through phase transition. They have good energy storage (cold storage, heat storage) performance and have been widely used in aerospace, building energy conservation, industrial waste heat recovery and other fields in recent years.

[0003] "Liquid cooling" is a cooling method with high heat exchange efficiency. If phase change materials are mixed into the coolant, the temperature control effect can be further optimized in the form of latent heat, reducing the temperature fluctuation of the coolant system, thereby achieving a continuous temperature control effect. However, phase change materials often flow during the phase change process, so in order to avoid fusion in the coolant, they must be encapsulated during actual application. The "microencapsulation" method is considered to be a very effective micro-encapsulation method. With the deepening of research, the preparation method of phase change microcapsules has also made great progress. In recent years, a variety of phase change microcapsules have been developed, and have shown good application prospects in the fields of building energy conservation and constant temperature clothing, expanding the application field of phase change materials.

[0004] In recent years, relevant patents have been published on phase change microcapsules and their preparation technology. According to the classification of wall materials, they can usually be divided into three types: organic, inorganic and organic / inorganic hybrid wall materials. Among them, organic / inorganic hybrid wall material phase change microcapsules have excellent structural stability and solvent resistance compared to single component wall materials, and can be used for oil-based coolants. However, traditional organic / inorganic hybrid wall materials are usually composite materials of resin polymers and inorganic substances, and their thermal conductivity is low, resulting in a large thermal resistance at the interface between the phase change material and the oil-based coolant. Therefore, the development of phase change microcapsules with high thermal conductivity can greatly improve the temperature control efficiency of oil-based coolants. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, the present invention provides a method for preparing a thermally conductive enhanced phase change microcapsule in a first aspect, the method comprising the following steps:

[0006] 1) preparing a dispersed phase, wherein the dispersed phase is prepared by dissolving an inorganic reaction precursor, an organic resin monomer, an oil-soluble thermal conductive filler, a crosslinking agent and an initiator in a molten phase change material;

[0007] 2) preparing a continuous phase, wherein the continuous phase is prepared by dispersing an emulsifier and a water-soluble thermally conductive material in a polar solvent;

[0008] 3) dispersing the dispersed phase in the continuous phase to obtain a microemulsion by emulsification;

[0009] 4) causing the inorganic reaction precursor in the microemulsion to undergo an interfacial reaction at a first temperature, and then initiating a polymerization reaction of the organic resin monomer in the microemulsion using the initiator in the presence of the crosslinking agent at a second temperature, and then separating the phase change microcapsules as a solid phase product.

[0010] In a second aspect, the present invention provides phase change microcapsules prepared by the preparation method described in the first aspect of the present invention.

[0011] In a third aspect, the present invention provides a method for preparing a thermally conductive enhanced phase change coolant, the method comprising the steps of adding phase change microcapsules to an oil-based coolant and mixing them evenly to prepare the thermally conductive enhanced phase change coolant, wherein the phase change microcapsules are prepared by the preparation method described in the first aspect of the present invention.

[0012] The present invention, in a fourth aspect, provides a heat-conductivity-enhanced phase-change coolant prepared by the method described in the third aspect of the present invention.

[0013] In a fifth aspect, the present invention provides use of the phase change microcapsules described in the second aspect of the present invention in preparing a phase change coolant.

[0014] The method of the present invention has the following advantages:

[0015] (1) The core material and the wall material of the phase change microcapsule of the present invention are respectively composed of heat conductive materials to form a heat conductive network, which greatly improves the heat exchange efficiency of the phase change microcapsule;

[0016] (2) The surface of the phase change microcapsule of the present invention is composed of inorganic / organic dual components and has good solvent resistance.

[0017] (3) The coverage rate of the phase change microcapsules of the present invention on the phase change material is high, even up to 90% or more.

[0018] (4) The oil-based phase change coolant of the present invention has excellent thermal conductivity and is a thermally conductive enhanced oil-based phase change coolant. Moreover, the amount of phase change material added therein can reach more than 10%, and has a good temperature control effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a process flow chart for preparing the phase change microcapsules.

[0020] Figure 2This is a SEM image of the phase change microcapsules prepared in Example 1 of the present application.

[0021] Figure 3 This is a comparison of the temperature rise curves of the oil-based coolant prepared by the phase change microcapsules obtained in Examples 1, 7, 8, and 9 of the present application under the condition of a heat source power of 28 W. Curve 1 is the temperature rise curve of Example 1; Curve 2 is the temperature rise curve of Example 7; Curve 3 is the temperature rise curve of Example 8; Curve 4 is the temperature rise curve of Example 9. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In a first aspect, the present invention provides a method for preparing a thermally conductive enhanced phase change microcapsule, the method comprising the following steps:

[0024] (1) preparing a dispersed phase, wherein the dispersed phase is prepared by dissolving an inorganic reaction precursor, an organic resin monomer, an oil-soluble thermal conductive filler, a crosslinking agent and an initiator in a molten phase change material;

[0025] (2) preparing a continuous phase, wherein the continuous phase is prepared by dispersing an emulsifier and a water-soluble thermally conductive material in a polar solvent;

[0026] (3) dispersing the dispersed phase in the continuous phase to obtain a microemulsion by emulsification;

[0027] (4) causing an inorganic reaction precursor in the microemulsion to undergo an interfacial reaction at a first temperature, and then initiating a polymerization reaction of the organic resin monomer in the microemulsion using the initiator in the presence of the crosslinking agent at a second temperature, and then separating the phase change microcapsules as a solid phase product.

[0028] In some preferred embodiments, the oil-soluble thermally conductive filler is at least one selected from the group consisting of expanded graphite, carbon nanotubes, and graphene.

[0029] In other preferred embodiments, the water-soluble thermally conductive material is at least one selected from the group consisting of carboxyl carbon nanotubes, graphene oxide, aluminum oxide nanoparticles, magnesium oxide nanoparticles, and iron oxide nanoparticles.

[0030] In some preferred embodiments, the mass ratio of the total mass of the oil-soluble thermal conductive filler to the phase change material is 1:0.1-100 (e.g., 1:0.1, 1, 5, 10, 20, 50 or 100), preferably 1:1-50; and / or

[0031] In other preferred embodiments, the mass ratio of the total mass of the water-soluble thermally conductive material to the polar solvent is 1:0.1-100 (for example, 1:0.1, 1, 5, 10, 20, 50 or 100), preferably 1:1-50.

[0032] In some embodiments, the inorganic reaction precursor is selected from at least one of the group consisting of tetrabutyl titanate, tetraisopropyl titanate, ethyl orthosilicate, epoxypropyl trimethoxysilane, phenyl triethoxysilane, methacryloxypropyl trimethoxysilane, methacryloxypropyl triethoxysilane, aminopropyl trimethoxysilane, aminopropyl triethoxysilane, phenyl trimethoxysilane, n-octyl triethoxysilane, tetrabutyl stannate, tetrabutyl zirconate, triisopropyl aluminate, and benzyl aluminate.

[0033] In other embodiments, the organic resin monomer is selected from C n H 2n At least one of the group consisting of olefins (wherein n is an integer and 2≤n≤20, such as n=2, 3, 5, 10, 15 or 20), styrene, methylstyrene, methyl methacrylate, ethyl methacrylate, butyl methacrylate, tert-butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, tert-butyl acrylate and isooctyl acrylate.

[0034] In other embodiments, the crosslinking agent is a multiolefin type crosslinking agent, and more preferably, the crosslinking agent is at least one selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, butylene glycol dimethacrylate and hexanediol dimethacrylate.

[0035] In other embodiments, the initiator is at least one selected from the group consisting of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide.

[0036] In other embodiments, the phase change material is a solid-liquid phase change material. More preferably, the phase change material is selected from at least one of the group consisting of alcohol compounds, organic acid compounds, ester compounds, and alkane compounds; preferably, the alcohol compound is selected from at least one of the group consisting of propylene glycol, butanetetraol, dodecanol, tetradecanol, hexadecanol, and erythritol; further preferably, the organic acid compound is selected from at least one of the group consisting of caprylic acid, capric acid, dodecanoic acid, tetradecanol, hexadecanoic acid, octadecanoic acid, lauric acid, myristic acid, palmitic acid, and stearic acid; further preferably, the ester compound is selected from at least one of the group consisting of cellulose laurate and hexadecyl stearate; further preferably, the alkane compound is selected from at least one of the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons with a carbon number of 8 to 100 (e.g., 8, 10, 20, 50 or 100) (e.g., n-octadecane), and paraffin with a melting point of 14°C to 80°C (e.g., 15, 20, 40, 60 or 80).

[0037] In other embodiments, the mass ratio of the inorganic reaction precursor to the organic resin monomer is 1:0.1 to 100 (for example, 1:0.1, 1, 5, 10, 50 or 100), preferably 1:1 to 50. In addition, preferably, the mass ratio of the total mass of the inorganic reaction precursor and the organic resin monomer to the phase change material is 1:0.1 to 100 (for example, 1:0.1, 1, 5, 10, 20, 50 or 100), preferably 1:1 to 50.

[0038] In some preferred embodiments, the emulsifier is selected from at least one of the group consisting of sodium salt hydrolyzate of vinyl methyl ether-maleic anhydride copolymer, sodium salt hydrolyzate of isobutylene-maleic anhydride copolymer, sodium salt hydrolyzate of styrene-maleic anhydride copolymer, sodium salt hydrolyzate of ethylene-maleic anhydride copolymer, copolymers obtained by copolymerization of acrylic acid or methacrylic acid with styrene, ethylene, vinyl alcohol, vinyl acetate, methacrylamide, isobutylene, acrylate, methacrylate or acrylonitrile, polyvinyl benzene sulfonic acid, sodium polyvinyl benzene sulfonate, octylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, Tween 20 (Tween20), Tween 60 (Tween60), Tween 80 (Tween80), polyethylene glycol octylphenyl ether X-100 (Triton X-100), sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide and sodium dioctyl persulfonate.

[0039] In some preferred embodiments, the polar solvent is at least one selected from the group consisting of water, methanol, tetrahydrofuran, and N,N-dimethylformamide.

[0040] In some preferred embodiments, the mass ratio of the emulsifier to the polar solvent is 1:1-100 (eg, 1:1, 5, 10, 20, 50 or 100); preferably 1:50-100.

[0041] In some preferred embodiments, the volume ratio of the dispersed phase to the continuous phase is 1:1 to 100 (e.g., 1:1, 5, 10, 20, 50 or 100); preferably 1:1 to 50. In addition, preferably, the emulsifier accounts for 0.5 to 30% (e.g., 0.5, 1, 5, 10, 20 or 30%) of the mass of the emulsion, preferably 1 to 20%.

[0042] In some preferred embodiments, the emulsification is achieved by shear emulsification. Preferably, the shear rate of the shear emulsification is in the range of 1000 rpm to 25000 rpm (for example, 1000, 5000, 10000, 15000, 20000 or 25000 rpm), and the shear time is in the range of 0.5 min to 30 min (for example, 0.5, 1, 5, 10, 15, 20 or 30 minutes).

[0043] In other preferred embodiments, the emulsification is achieved by ultrasonic emulsification. Preferably, the ultrasonic frequency of the ultrasonic emulsification is in the range of 1000 Hz to 40000 Hz (for example, 1000, 5000, 10000, 20000, 30000 or 40000 Hz), and the ultrasonic emulsification time is in the range of 10 minutes to 60 minutes (for example, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 minutes).

[0044] In some preferred embodiments, the first temperature is 10°C to 30°C (e.g., 20°C), and the reaction time is 0.5 to 72 hours (e.g., 0.5, 1, 3, 6, 9, 12, 24, 36, 48, 60, or 72 hours). The second temperature is 50°C to 80°C (e.g., 60 or 70°C), and the reaction time is 0.5 to 72 hours (e.g., 0.5, 1, 3, 6, 9, 12, 24, 36, 48, 60, or 72 hours).

[0045] In some preferred embodiments, in step (2), the step of adjusting the pH value of the continuous phase to 1 to 14 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14), preferably to 2 to 12, is further included. The present invention has no particular limitation on the selection of the acid or base used to adjust the pH value and its concentration, as long as it is applicable to the reaction system described in the present invention. As an example, the acid can be selected from at least one of the group consisting of hydrochloric acid, sulfuric acid and nitric acid, and the base can be selected from at least one of the group consisting of sodium hydroxide, potassium hydroxide and aqueous ammonia.

[0046] In some preferred embodiments, in step (4), the solid phase product is further washed and dried. In some preferred embodiments, the separation is carried out by centrifugation, and the centrifugal speed is 3000-15000 rpm (e.g., 5000 or 10000 rpm), and the centrifugal time is 2-30 minutes (e.g., 5, 10, 15, 20, 25 or 30 minutes). In some preferred embodiments, the separation is carried out by suction filtration, and the filter paper pore size used for the suction filtration is 50 μm-500 μm (50, 100, 200, 300, 400 or 500 μm).

[0047] In some preferred embodiments, the dispersion described in step (2) and step (3) can be independently achieved by high-speed shearing. Preferably, the shearing speed of the dispersion can be independently 1000 rpm to 25000 rpm (for example, 1000, 5000, 10000, 15000, 20000 or 25000 rpm), and the shearing time can be independently 0.5 minute to 30 minutes (for example, 0.5, 1, 5, 10, 15, 20 or 30 minutes).

[0048] In some preferred embodiments, the dispersion in step (2) and step (3) can be independently achieved by ultrasound. Preferably, the ultrasonic frequency of the ultrasonic dispersion can be in the range of 1000 Hz to 40000 Hz (e.g., 1000, 5000, 10000, 20000, 30000 or 40000 Hz), and the ultrasonic treatment time can be 10 minutes to 60 minutes (e.g., 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 minutes).

[0049] In a second aspect, the present invention provides phase change microcapsules prepared by the preparation method described in the first aspect of the present invention.

[0050] In addition, the phase change microcapsules of the present invention are thermally conductive enhanced phase change microcapsules, and the phase change temperature can be 14 to 80°C (for example, 15, 20, 25, 30, 35, 40, 45 or 50°C); preferably 50 to 70°C; the phase change latent heat can be 30 J / g to 240 J / g (for example, 30, 40, 50, 60, 70, 80, 90, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230 or 240 J / g), preferably 100 J / g to 230 J / g.

[0051] The thermally conductive enhanced phase-change microcapsules prepared by the method of the present invention include a core material and a wall material; the core material contains a phase-change material or is composed of a phase-change material, and contains a lipophilic thermally conductive material; the wall material is a hybrid wall material obtained by hybridizing an inorganic material and an organic material, and the thermally conductive enhanced material is evenly distributed on the surface; the enthalpy value retention rate of the thermally conductive enhanced phase-change microcapsules can be 75% to 99%, preferably 80% to 93%.

[0052] According to the present invention, the hybrid wall material includes an inorganic wall material and a polymer wall material. The inorganic wall material can be SiO 2 、TiO 2 SnO 2 、ZrO 2 and Al 2 O 3 The organic wall material may be at least one of the group consisting of polystyrene, polymethyl methacrylate, polyethyl methacrylate, and polybutyl methacrylate.

[0053] In the present invention, the enthalpy retention rate of the phase change microcapsules coated with the hybrid wall material is consistent with the coating rate and the core material content, and can be calculated by the melting enthalpy or crystallization enthalpy, and the calculation method is as follows:

[0054] Enthalpy retention rate = coverage rate = core material content = ΔH m / ΔH m0 ×100%;

[0055] Wall material content = 100% - core material content;

[0056] Where ΔH m0 is the phase change point enthalpy of the core material of the phase change microcapsule, ΔH m is the phase change point enthalpy of phase change microcapsules.

[0057] In addition, the phase change temperature of the thermally conductive enhanced phase change microcapsules prepared by the method of the present invention can be 14 to 52°C (for example, 15, 20, 25, 30, 35, 40, 45 or 50°C); preferably 20 to 40°C; the phase change latent heat can be 30 J / g to 240 J / g (for example, 30, 40, 50, 60, 70, 80, 90, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230 or 240 J / g), preferably 100 J / g to 230 J / g.

[0058] In a third aspect, the present invention provides a method for preparing a thermally conductive enhanced phase change coolant, the method comprising the steps of adding phase change microcapsules to an oil-based coolant and mixing them evenly to prepare the thermally conductive enhanced phase change coolant, wherein the phase change microcapsules are prepared by the preparation method described in the first aspect of the present invention, i.e., the phase change microcapsules described in the second aspect of the present invention.

[0059] In some preferred embodiments, the oil-based coolant is selected from at least one of dimethyl silicone oil, octamethyltrisiloxane, 3# white oil, 5# white oil, 7# white oil, and 10# white oil.

[0060] In some preferred embodiments, the phase change microcapsules of the phase change coolant prepared by the method of the present invention may account for 0.5-30% (eg, 0.5, 1, 5, 10, 20 or 30%), preferably 1-20% of the mass of the phase change coolant finally prepared.

[0061] As described above, the present invention adopts an inorganic reaction precursor and obtains a phase change material coated with an inorganic-organic hybrid wall material through a two-step reaction on the emulsion interface. Since the thermal conductive material is compounded in both the core material and the wall material, the oil-based phase change coolant prepared by the phase change microcapsule has a significantly reduced thermal resistance at the interface between the phase change material and the oil-based coolant, and can be widely used in the field of temperature control of high-power electronic equipment.

[0062] Therefore, the present invention provides, in a fourth aspect, a thermally conductive enhanced phase change coolant prepared by the method described in the third aspect of the present invention.

[0063] In a fifth aspect, the present invention provides the use of the phase change microcapsules described in the second aspect of the present invention in the preparation of phase change coolants. The organic / inorganic hybrid wall material of conventional phase change microcapsules is usually a composite material of resin polymers and inorganic substances, and has a low thermal conductivity. If it is used to prepare an oil-based phase change coolant with an oil-based coolant, there is a problem that the temperature control efficiency of the oil-based phase change coolant is insufficient. However, the thermal conductivity of the organic / inorganic hybrid wall material is limited by the poor resistance to oil-based coolants, and it is very difficult to improve. Generally, a thermal conductive material is added to the oil-based coolant to solve this problem. However, such an operation will cause the thermal conductive material to damage the phase change microcapsules, and there is a large thermal resistance at the interface between the phase change material and the oil-based coolant, and the improvement in temperature control efficiency is limited. The phase change microcapsules prepared by the present invention solve the above problems.

[0064] Therefore, the development of phase change microcapsules with high thermal conductivity can greatly improve the temperature control efficiency of oil-based coolants.

[0065] Example

[0066] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content recorded in the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the present invention equally.

[0067] Example 1

[0068] Take 5g of tetrabutyl titanate, 1g of styrene, 0.1g of divinylbenzene, 0.1g of azobisisobutyronitrile and 2g of expanded graphite and add them to 30g of molten n-octadecane, mix them thoroughly and use them as dispersed phase. Take 2.5g of sodium dodecyl sulfate and 0.25g of carboxyl carbon nanotubes and add them to 50g of water as continuous phase, and adjust the pH of the continuous phase to 5 with hydrochloric acid at a concentration of 2M. Add the dispersed phase to the continuous phase, emulsify it by high-speed shearing, the emulsification time is 20min, the shear rate is 10000rpm, and then transfer the obtained emulsion to a three-necked flask. After reacting for 6 hours at 20°C, the system is heated to 70°C and reacted at 70°C for 12 hours. The product is separated by centrifugation at 12000rpm, washed with deionized water, and then dried in vacuo to obtain a phase change microcapsule powder. The phase change latent heat data of the thermally conductive enhanced phase change microcapsules prepared in this embodiment are shown in Table 1.

[0069] 20 g of the thermally conductive enhanced phase change microcapsules prepared in this example were dispersed in 85 g of 3# white oil by high-speed shearing (20,000 rpm) to obtain a high thermal conductive oil-based phase change coolant.

[0070] Example 2

[0071] Take 5g of aminopropyltrimethoxysilane, 1g of styrene, 0.1g of divinylbenzene, 0.05g of azobisisobutyronitrile and 5g of carbon nanotubes and add them to 20g of molten n-hexadecane, mix them thoroughly and use them as the dispersed phase. Take 1g of Tween 80 and 2g of alumina nanopowder and add them to 50g of water as the continuous phase. Add the dispersed phase to the continuous phase and emulsify it with ultrasound at a frequency of 3000Hz for 30min. Transfer the resulting emulsion to a three-necked flask and react at 30°C for 6 hours. Then, heat the system to 70°C and react at 70°C for 12 hours. Separate the product by centrifugation at 12000rpm, wash with deionized water, and then vacuum dry to obtain thermally conductive enhanced phase change microcapsules.

[0072] 10 g of the phase-change microcapsules with enhanced thermal conductivity prepared in this example were dispersed in 100 g of 5# white oil by high-speed shearing (10000 rpm) to obtain a high thermal conductivity oil-based phase-change coolant.

[0073] Example 3

[0074] Take 10g of tetraethyl orthosilicate, 3g of methyl methacrylate, 1.5g of divinylbenzene, 0.05g of azobisisobutyronitrile, and 3g of graphene and add them to 50g of molten n-octadecane, mix them thoroughly and use them as the dispersed phase. Take 1g of CTAB (hexadecyltrimethylammonium bromide) and 0.5g of carboxyl carbon nanotubes and add them to 50g of water as the continuous phase, and adjust the pH value of the continuous phase to 10 with 1M ammonia water. Add the dispersed phase to the continuous phase, use a high-speed shear emulsifier to shear and emulsify at 10000rpm for 10min, transfer the resulting emulsion to a three-necked flask, react at 30°C for 12 hours, heat the system to 50°C, and react at 50°C for 12 hours. Separate the product by centrifugation at 12000rpm, wash with deionized water, and obtain a phase change microcapsule powder with enhanced thermal conductivity by vacuum drying.

[0075] 20 g of the thermally conductive enhanced phase change microcapsules prepared in this example were dispersed in 800 g of 3# white oil by high-speed shearing (20,000 rpm) to obtain a highly thermally conductive oil-based phase change coolant.

[0076] Example 4

[0077] Take 8g of tetrabutyl titanate, 2g of butyl methacrylate, 0.2g of ethylene glycol dimethyl diacrylate, 0.05g of benzoyl peroxide and 3g of expanded graphite and add them to 30g of molten n-eicosane, and mix them thoroughly as the dispersed phase. Take 1g of polyethylene glycol octylphenyl ether X-100 (Triton X-100) and 0.2 graphene oxide and add them to 50g of water as the continuous phase, and adjust the pH of the continuous phase to 5 using 2M hydrochloric acid. Add the dispersed phase to the continuous phase, use a high-speed shear emulsifier to shear and emulsify at 10000rpm for 10min, transfer the resulting emulsion to a three-necked flask, react at 30°C for 6 hours, heat the system to 70°C, and react at 70°C for 12 hours. The product is separated by centrifugation at 12000rpm, washed with deionized water, and then dried in vacuum to obtain a phase change microcapsule powder. The phase change latent heat data of the thermally conductive enhanced phase change microcapsules prepared in this embodiment are shown in Table 1.

[0078] 18 g of the phase-change microcapsules with enhanced thermal conductivity prepared in this example were dispersed in 100 g of 3# white oil by high-speed shearing (20,000 rpm) to obtain a high thermal conductivity oil-based phase-change coolant.

[0079] Example 5

[0080] Take 4.5g of methacryloyloxypropyl trimethoxysilane, 2g of propylene, 0.1g of divinylbenzene, 0.05g of azobisisobutyronitrile and 3g of carbon nanotubes and dissolve them in 28g of molten n-eicosane, mix them thoroughly and use them as the dispersed phase. Take 1g of hexadecyltrimethylammonium bromide and 1g of carboxyl carbon nanotubes and add them to 50g of water as the continuous phase, and adjust the pH of the continuous phase to 10 with dilute ammonia water with a concentration of 0.5M. Add the dispersed phase to the continuous phase, emulsify the above mixture with ultrasound for 30min, transfer the resulting microemulsion to a three-necked flask, react at 25°C for 12 hours, heat the system to 70°C, and react at 70°C for 12 hours. The product is separated by suction filtration, washed with deionized water, and then vacuum dried to obtain thermally conductive enhanced phase change microcapsules. The phase change latent heat data of the thermally conductive enhanced phase change microcapsules prepared in this embodiment are shown in Table 1.

[0081] 20 g of the phase-change microcapsules with enhanced thermal conductivity prepared in this example were dispersed in 200 g of 5# white oil by high-speed shearing (20,000 rpm) to obtain a high thermal conductivity oil-based phase-change coolant.

[0082] Example 6

[0083] Take 6g of tetrabutyl titanate, 3g of butyl methacrylate, 0.5g of ethylene glycol dimethyl diacrylate, 0.05g of benzoyl peroxide, and 5g of graphene and dissolve them in 25g of molten tetradecanol, and mix them thoroughly as the dispersed phase. Take 1g of Tween and 0.2g of graphene oxide and add them to 45g of water as the continuous phase, and adjust the pH of the continuous phase to 6 using 1M hydrochloric acid. Add the dispersed phase to the continuous phase, use a high-speed shear emulsifier to shear and emulsify at 10000rpm for 10min, transfer the resulting emulsion to a three-necked flask, react at 30°C for 1 hour, heat the system to 70°C, and react at 70°C for 12 hours. The product is separated by centrifugation at 15000rpm, washed with deionized water, and then dried in vacuo to obtain a phase change microcapsule powder. The phase change latent heat data of the thermally conductive enhanced phase change microcapsules prepared in this embodiment are shown in Table 1.

[0084] 20 g of the phase-change microcapsules with enhanced thermal conductivity prepared in this example were dispersed in 200 g of 5# white oil by high-speed shearing (20,000 rpm) to obtain a high thermal conductivity oil-based phase-change coolant.

[0085] Example 7

[0086] The method is basically the same as that of Example 1, except that no thermal conductive material is added during the preparation of the dispersed phase and the continuous phase.

[0087] Example 8

[0088] The method was basically the same as that of Example 1, except that no oil-soluble thermally conductive filler was added to the dispersed phase, and 0.5 g of graphene oxide was introduced during the preparation of the continuous phase.

[0089] Example 9

[0090] The method was basically the same as that of Example 1, except that 3 g of expanded graphite was added as an oil-soluble thermally conductive filler during the preparation of the dispersed phase, and no thermally conductive material was added during the preparation of the continuous phase.

[0091] The inventors measured the phase change temperature and enthalpy retention rate of the phase change microcapsules prepared in each embodiment and the cooling efficiency of the high thermal conductivity oil-based phase change coolant.

[0092] The enthalpy retention rate of the phase change temperature of the phase change microcapsule is consistent with the coverage rate and the core material content, so it is calculated by the melting enthalpy or crystallization enthalpy. The calculation method is as follows:

[0093] Enthalpy retention rate = coverage rate = core material content = ΔH m / ΔH m0 ×100%;

[0094] Wall material content = 100% - core material content;

[0095] Where ΔH m0 is the phase change point enthalpy of the core material of the phase change microcapsule, ΔH m is the phase change point enthalpy of phase change microcapsules.

[0096] The cooling efficiency of high thermal conductivity oil-based phase change coolant is determined as follows: each oil-based phase change coolant is heated by a heat source power of 28W, and the temperature rise of the phase change coolant is measured by a thermocouple, and a curve is drawn as follows: Figure 3 shown.

[0097] Table 1. Properties of the phase change composite materials prepared in various embodiments.

[0098]

[0099]

[0100] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing thermally conductive enhanced phase change microcapsules, characterized in that: The method comprises the following steps: (1) preparing a dispersed phase, wherein the dispersed phase is prepared by dissolving an inorganic reaction precursor, an organic resin monomer, an oil-soluble thermal conductive filler, a crosslinking agent and an initiator in a molten phase change material; (2) preparing a continuous phase, wherein the continuous phase is prepared by dispersing an emulsifier and a water-soluble thermally conductive material in a polar solvent; (3) dispersing the dispersed phase in the continuous phase to obtain a microemulsion by emulsification; (4) causing an inorganic reaction precursor in the microemulsion to undergo an interfacial reaction at a first temperature, and then initiating a polymerization reaction of the organic resin monomer in the microemulsion using the initiator in the presence of the crosslinking agent at a second temperature, and then separating the phase change microcapsules as a solid phase product.

2. The preparation method according to claim 1, characterized in that: The oil-soluble thermally conductive filler is at least one selected from the group consisting of expanded graphite, carbon nanotubes, and graphene; and / or The water-soluble thermally conductive material is at least one selected from the group consisting of carboxyl carbon nanotubes, graphene oxide, aluminum oxide nanoparticles, magnesium oxide nanoparticles, and iron oxide nanoparticles.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the total mass of the oil-soluble thermal conductive filler to the phase change material is 1:0.1 to 100, preferably 1:1 to 50; and / or The mass ratio of the total mass of the water-soluble thermally conductive material to the polar solvent is 1:0.1-100, preferably 1:1-50.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The inorganic reaction precursor is selected from at least one of the group consisting of tetrabutyl titanate, tetraisopropyl titanate, ethyl orthosilicate, epoxypropyl trimethoxysilane, phenyl triethoxysilane, methacryloxypropyl trimethoxysilane, methacryloxypropyl triethoxysilane, aminopropyl trimethoxysilane, aminopropyl triethoxysilane, phenyl trimethoxysilane, n-octyl triethoxysilane, tetrabutyl stannate, NW-2 stannate coupling agent, tetrabutyl zirconate, triisopropyl aluminate, and benzyl aluminate; The organic resin monomer is selected from C n H 2n At least one of the group consisting of olefins, styrene, methylstyrene, methyl methacrylate, ethyl methacrylate, butyl methacrylate, tert-butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, tert-butyl acrylate and isooctyl acrylate, wherein n is an integer and 2≤n≤20; The crosslinking agent is a multiolefin crosslinking agent, and more preferably, the crosslinking agent is at least one selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, butylene glycol dimethacrylate, ethylene glycol dimethacrylate and hexanediol dimethacrylate; The initiator is selected from at least one of the group consisting of azobisisobutyronitrile, azobisisoheptylnitrile and benzoyl peroxide; the phase change material is a solid-liquid phase change material, and more preferably, the phase change material is selected from at least one of the group consisting of alcohol compounds, organic acid compounds, ester compounds, and alkane compounds; preferably, the alcohol compound is selected from at least one of the group consisting of propylene glycol, butanetetraol, dodecanol, tetradecanol, hexadecanol, and erythritol; further preferably, the organic acid compound is selected from at least one of the group consisting of octanoic acid, decanoic acid, dodecanoic acid, tetradecanol, hexadecanoic acid, octadecanoic acid, lauric acid, myristic acid, palmitic acid, and stearic acid; further preferably, the ester compound is selected from at least one of the group consisting of cellulose laurate and hexadecyl stearate; further preferably, the alkane compound is selected from at least one of the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons with a carbon number of 8 to 100 such as n-octadecane, and paraffin with a melting point of 14°C to 80°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The mass ratio of the inorganic reaction precursor to the organic resin monomer is 1:0.1 to 100, preferably 1:1 to 50; The mass ratio of the total mass of the inorganic reaction precursor and the organic resin monomer to the mass ratio of the phase change material is 1:0.1-100, preferably 1:1-50.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The emulsifier is selected from at least one of the group consisting of sodium salt hydrolyzate of vinyl methyl ether-maleic anhydride copolymer, sodium salt hydrolyzate of isobutylene-maleic anhydride copolymer, sodium salt hydrolyzate of styrene-maleic anhydride copolymer, sodium salt hydrolyzate of ethylene-maleic anhydride copolymer, copolymers obtained by copolymerization of acrylic acid or methacrylic acid with styrene, ethylene, vinyl alcohol, vinyl acetate, methacrylamide, isobutylene, acrylate, methacrylate or acrylonitrile, polyvinylbenzenesulfonic acid, sodium polyvinylbenzenesulfonate, octylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, Tween 20, Tween 60, Tween 80, polyethylene glycol octylphenyl ether X-100, sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide and sodium dioctyl sulfonate of acrylonitrile; and / or The polar solvent is at least one selected from the group consisting of water, methanol, tetrahydrofuran, and N,N-dimethylformamide.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The mass ratio of the emulsifier to the polar solvent is 1:1 to 100, preferably 1:50 to 100; and / or The volume ratio of the dispersed phase to the continuous phase is 1:1-100, preferably 1:1-50.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The first temperature is 10°C to 30°C, and the reaction time is 0.5 hours to 72 hours; and / or The second temperature is 50° C. to 80° C., and the reaction time is 0.5 hour to 72 hours.

9. A method for preparing a thermally conductive enhanced phase change coolant, characterized in that: The method comprises the steps of adding phase change microcapsules into an oil-based coolant and mixing them uniformly to prepare the thermally conductive enhanced phase change coolant, wherein the phase change microcapsules are prepared by the preparation method described in any one of claims 1 to 8; Preferably, the oil-based coolant is selected from at least one of dimethyl silicone oil, octamethyltrisiloxane, 3# white oil, 5# white oil, 7# white oil, and 10# white oil. 10 . The thermally conductive enhanced phase-change microcapsules prepared by the preparation method according to any one of claims 1 to 8 or the thermally conductive enhanced phase-change coolant prepared by the method according to claim 9 .

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