Phase change microcapsule with two-stage temperature control capability and preparation method thereof

Abstract

The present disclosure relates to the technical field of multifunctional phase change material, and particularly relates to a phase change microcapsule with two-stage temperature control capability and a preparation method thereof.The phase change microcapsule in the present disclosure comprises the following components by weight: methyl stearate (MS) 100 parts; polyethylene glycol (PEG) 50-70 parts; polycarbonate diol (PCDL) 20-40 parts; isophorone diisocyanate (IPDI) 15-30 parts; emulsifier 5-10 parts; heat-conducting filler 1-5 parts; crosslinking agent 0.5-1 part.The phase change microcapsule takes MS as the core, and takes the three-block polyurethane composed of IPDI, PCDL and PEG as the shell, and is endowed with the two-stage temperature control capability, so that it has great application value in the field of lithium battery thermal management.

Description

Technical Field

[0001] The present disclosure relates to the technical field of multifunctional phase change materials, and in particular to a phase change microcapsule with two-stage temperature control capability and a preparation method thereof. Background Art

[0002] Phase change materials (PCMs) are ideal heat storage media, releasing or storing large amounts of latent heat during isothermal phase transitions, thereby achieving temperature control. However, the solid-liquid phase transition inevitably causes leakage during use.

[0003] Phase-change microcapsules are a special type of composite material that encapsulates phase-change materials in tiny capsules to improve their leakage, phase separation, and thermal performance. Traditional phase-change microcapsules often use organic or inorganic materials as the shell, encapsulating a single phase-change material core through emulsion polymerization or interfacial polymerization.

[0004] The phase-change microcapsules obtained by this method only have one phase-change temperature, which cannot meet the requirements of segmented temperature control for some products. Furthermore, phase-change microcapsules with a single phase-change temperature have a low fault tolerance rate. If they fail after multiple thermal cycles, they may cause irreversible damage to the product. Summary of the Invention

[0005] In view of the deficiencies or problems existing in the prior art, the present disclosure provides a phase-change microcapsule with two-stage temperature control capability and a preparation method thereof. The phase-change microcapsule also has good thermal performance and thermal cycle stability.

[0006] The technical solution adopted by the present disclosure to solve the above technical problems is: a phase change microcapsule with two-stage temperature control capability, comprising the following components by weight: 100 parts of methyl stearate (MS); 50-70 parts of polyethylene glycol (PEG); 20-40 parts of polycarbonate diol (PCDL); 15-30 parts of isophorone diisocyanate (IPDI); 5-10 parts of emulsifier; 1-5 parts of thermal conductive filler; and 0.5-1 part of cross-linking agent.

[0007] Preferably, the melting point of the MS is 38-44°C, and the density at 25°C is 0.86 g / cm 3 .

[0008] Preferably, the PEG is one or a combination of two or more of PEG-4000, PEG-6000, and PEG-8000.

[0009] Preferably, the PCDL has a number average molecular weight of 800 g / mol, a viscosity of 600 to 1200 mPa·s, and an OH value of 200 to 250 mgKOH / g.

[0010] Preferably, the IPDI has a molecular weight of 222.32 g / mol, a viscosity of 10 mPa·s, and an isocyanate content of 37.5 to 45 wt%.

[0011] Preferably, the emulsifier is one or a combination of two or more of polyvinyl alcohol, sodium lauryl sulfate, and cetyltrimethylammonium bromide.

[0012] Preferably, the thermally conductive filler is one or a combination of two or more of aluminum nitride, boron nitride, and aluminum oxide.

[0013] Preferably, the cross-linking agent is one or a combination of two or more of trimethylolpropane, triethanolamine and melamine.

[0014] The phase change microcapsule with two-stage temperature control capability comprises the following steps:

[0015] S1. Add MS, PCDL, IPDI, and thermal conductive filler into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0016] S2. Disperse the emulsifier in 150 ml of deionized water at 80°C and stir evenly for later use;

[0017] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0018] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0019] S5. Add the crosslinking agent to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. to react for 6 h;

[0020] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0021] Preferably, in S1, the melting point of the MS is 38-44°C, and the density at 25°C is 0.86 g / cm 3 .

[0022] The PCDL has a number average molecular weight of 800 g / mol, a viscosity of 600 to 1200 mPa·s, and an OH value of 200 to 250 mgKOH / g.

[0023] The IPDI has a molecular weight of 222.32 g / mol, a viscosity of 10 mPa·s, and an isocyanate content of 37.5 to 45 wt %.

[0024] The thermal conductive filler is one of aluminum nitride, boron nitride, and aluminum oxide, or a combination of two or more.

[0025] Preferably, in S2, the emulsifier is one or a combination of two or more of polyvinyl alcohol, sodium lauryl sulfate, and cetyltrimethylammonium bromide.

[0026] Preferably, in S4, the PEG is one or a combination of two or more of PEG-4000, PEG-6000, PEG-8000, and PEG-10000.

[0027] Preferably, in S5, the cross-linking agent is one or a combination of two or more of trimethylolpropane, triethanolamine, and melamine.

[0028] Compared with the prior art, the phase-change microcapsules disclosed herein have a two-stage temperature-control capability and are prepared by interfacial polymerization. The phase-change microcapsules use MS as the core for the first phase change, and a polyurethane shell composed of IPDI, PCDL, and PEG to encapsulate MS. The two-block polyurethane generated by IPDI and PCDL exhibits heat and hydrolysis resistance due to the presence of carbonate groups. The introduction of PEG into the shell also imparts the shell material with the ability to undergo a second phase change. The resulting product of the present disclosure has a two-stage temperature-control capability and also exhibits good thermal performance and thermal cycling stability.

[0029] Performance test of phase change microcapsules

[0030] Thermal properties were tested using a differential scanning calorimeter (DSC) in a nitrogen atmosphere over a temperature range of 0 to 80°C at a heating rate of 10°C / min.

[0031] Cyclic stability is tested using a temperature-controlled heating stage. This stage consists of an intelligent temperature control chamber (MY803-H) and an 1800W cast aluminum heating plate (dimensions: 300×200×20mm). The test method involves placing the sample on the heating stage and programming the temperature to 80°C for 30 minutes, followed by cooling to 30°C for 30 minutes. This cycle is repeated 500 times, and thermal performance is analyzed using a differential scanning calorimeter.

[0032] Thermal conductivity was tested using a TC3000E thermal conductivity meter. The sample was molded into a 30mm x 30mm x 5mm strip, which was then pressed against a sensor using a 500g weight. After thermal equilibrium was reached, each sample was tested five times, and the average result was calculated.

[0033] The present invention is described in detail below through specific embodiments. DETAILED DESCRIPTION

[0034] [Example 1]

[0035] This embodiment provides a phase-change microcapsule with two-stage temperature control capability, comprising the following components in parts by weight: 100 parts of MS; 50 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of polyvinyl alcohol; 3 parts of boron nitride; and 0.7 parts of trimethylolpropane.

[0036] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0037] S1. Add MS, PCDL, IPDI, and boron nitride into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0038] S2. Disperse polyvinyl alcohol in 150 ml of deionized water at 80° C. and stir until uniform;

[0039] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0040] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0041] S5. Add trimethylolpropane to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. for reaction for 6 h;

[0042] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0043] For the convenience of comparison, the experimental results are listed in Table 1.

[0044] [Example 2]

[0045] This embodiment provides a phase change microcapsule with two-stage temperature control capability, comprising the following components in parts by weight: 100 parts of MS; 60 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of sodium lauryl sulfate; 3 parts of aluminum oxide; and 0.7 parts of melamine.

[0046] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0047] S1. Add MS, PCDL, IPDI, and alumina into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0048] S2. Disperse sodium lauryl sulfate in 150 ml of deionized water at 80° C. and stir until uniform;

[0049] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0050] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0051] S5. Add melamine to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. to react for 6 h;

[0052] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0053] For the convenience of comparison, the experimental results are listed in Table 1.

[0054] [Example 3]

[0055] This embodiment provides a phase change microcapsule with two-stage temperature control capability, comprising the following components by weight: 100 parts of MS; 70 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of cetyltrimethylammonium bromide; 3 parts of aluminum nitride; and 0.7 parts of triethanolamine.

[0056] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0057] S1. Add MS, PCDL, IPDI, and aluminum nitride into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0058] S2. Disperse cetyltrimethylammonium bromide in 150 ml of deionized water, stir evenly at 80° C. and set aside;

[0059] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0060] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0061] S5. Add triethanolamine to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. to react for 6 h;

[0062] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0063] For the convenience of comparison, the experimental results are listed in Table 1.

[0064] [Example 4]

[0065] This embodiment provides a phase change microcapsule with two-stage temperature control capability, comprising the following components by weight: 100 parts of MS; 60 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of polyvinyl alcohol; 1 part of boron nitride; and 0.7 parts of trimethylolpropane.

[0066] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0067] S1. Add MS, PCDL, IPDI, and boron nitride into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0068] S2. Disperse polyvinyl alcohol in 150 ml of deionized water at 80° C. and stir until uniform;

[0069] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0070] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0071] S5. Add trimethylolpropane to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. for reaction for 6 h;

[0072] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0073] For the convenience of comparison, the experimental results are listed in Table 1.

[0074] [Example 5]

[0075] This embodiment provides a phase change microcapsule with two-stage temperature control capability, comprising the following components in parts by weight: 100 parts of MS; 60 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of polyvinyl alcohol; 5 parts of boron nitride; and 0.7 parts of trimethylolpropane.

[0076] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0077] S1. Add MS, PCDL, IPDI, and boron nitride into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0078] S2. Disperse polyvinyl alcohol in 150 ml of deionized water at 80° C. and stir until uniform;

[0079] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0080] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0081] S5. Add trimethylolpropane to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. for reaction for 6 h;

[0082] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0083] For the convenience of comparison, the experimental results are listed in Table 1.

[0084] [Example 6]

[0085] This embodiment provides a phase change microcapsule with two-stage temperature control capability, comprising the following components by weight: 100 parts of MS; 60 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of polyvinyl alcohol; 3 parts of boron nitride; and 0.5 parts of trimethylolpropane.

[0086] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0087] S1. Add MS, PCDL, IPDI, and boron nitride into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0088] S2. Disperse polyvinyl alcohol in 150 ml of deionized water at 80° C. and stir until uniform;

[0089] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0090] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0091] S5. Add trimethylolpropane to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. for reaction for 6 h;

[0092] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0093] For the convenience of comparison, the experimental results are listed in Table 1.

[0094] [Example 7]

[0095] This embodiment provides a phase change microcapsule with two-stage temperature control capability, comprising the following components in parts by weight: 100 parts of MS; 60 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of polyvinyl alcohol; 3 parts of boron nitride; and 1 part of trimethylolpropane.

[0096] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0097] S1. Add MS, PCDL, IPDI, and boron nitride into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0098] S2. Disperse polyvinyl alcohol in 150 ml of deionized water at 80° C. and stir until uniform;

[0099] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0100] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0101] S5. Add trimethylolpropane to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. for reaction for 6 h;

[0102] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0103] For the convenience of comparison, the experimental results are listed in Table 1.

[0104] [Comparative Example 1]

[0105] This embodiment provides a phase-change microcapsule with two-stage temperature control capability, comprising the following components in parts by weight: 100 parts of MS; 60 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of polyvinyl alcohol; and 0.7 parts of trimethylolpropane.

[0106] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0107] S1. Add MS, PCDL, and IPDI into a four-necked flask and stir at 80°C and 500 rpm under nitrogen atmosphere for prepolymerization for 2 h to prepare an oil phase system.

[0108] S2. Disperse polyvinyl alcohol in 150 ml of deionized water at 80° C. and stir until uniform;

[0109] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0110] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0111] S5. Add trimethylolpropane to the triblock copolymer at room temperature, stir at 500 r / min until uniformly dispersed, and then place in an oven at 60° C. for reaction for 6 h;

[0112] S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0113] For the convenience of comparison, the experimental results are listed in Table 1.

[0114] [Comparative Example 2]

[0115] This embodiment provides a phase-change microcapsule with two-stage temperature control capability, comprising the following components in parts by weight: 100 parts of MS; 60 parts of PEG; 30 parts of PCDL; 20 parts of IPDI; 8 parts of polyvinyl alcohol; and 3 parts of boron nitride.

[0116] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0117] S1. Add MS, PCDL, IPDI, and boron nitride into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0118] S2. Disperse polyvinyl alcohol in 150 ml of deionized water at 80° C. and stir until uniform;

[0119] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0120] S4. Slowly add PEG to the emulsion, and continue stirring at 80°C and 500 rpm for 4 h to obtain a triblock copolymer;

[0121] S5. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0122] For the convenience of comparison, the experimental results are listed in Table 1.

[0123] [Comparative Example 3]

[0124] This embodiment provides a phase change microcapsule with two-stage temperature control capability, comprising the following components in parts by weight: 100 parts of MS; 30 parts of PCDL; 20 parts of IPDI; 8 parts of polyvinyl alcohol; 3 parts of boron nitride; and 0.7 parts of trimethylolpropane.

[0125] The preparation method of the phase-change microcapsules with two-stage temperature control capability in this embodiment includes the following steps:

[0126] S1. Add MS, PCDL, IPDI, and boron nitride into a four-necked flask, and prepolymerize at 80°C and 500 rpm for 2 h under a nitrogen atmosphere to prepare an oil phase system.

[0127] S2. Disperse polyvinyl alcohol in 150 ml of deionized water at 80° C. and stir until uniform;

[0128] S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced;

[0129] S4, adding trimethylolpropane to the above diblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in a 60° C. oven to react for 6 h;

[0130] S5. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

[0131] For the convenience of comparison, the experimental results are listed in Table 1.

[0132] Table 1 (to be continued)

[0133] MS PEG PCDL IPDI emulsifiers Thermally conductive fillers crosslinking agent Example 1 100 50 30 20 8 3 0.7 Example 2 100 60 30 20 8 3 0.7 Example 3 100 70 30 20 8 3 0.7 Example 4 100 60 30 20 8 1 0.7 Example 5 100 60 30 20 8 5 0.7 Example 6 100 60 30 20 8 3 0.5 Example 7 100 60 30 20 8 3 1 Comparative Example 1 100 60 30 20 8 - 0.7 Comparative Example 2 100 60 30 20 8 3 - Comparative Example 3 100 - 30 20 8 3 0.7

[0134] Table 1 (continued)

[0135]

[0136] As can be seen from Table 1, compared with Comparative Example 1, Example 2 shows that the addition of thermally conductive fillers can significantly increase the thermal conductivity of the phase change microcapsules, with a thermal conductivity of 1.18 W / m·K, an increase of 70.3% compared with Comparative Example 1. Compared with Comparative Example 2, Example 2 shows that the addition of a crosslinking agent affects the encapsulation effect of the MS core. The shell without a crosslinking agent has poor density and exhibits a low phase change enthalpy. Compared with Comparative Example 3, Example 2 shows that the construction of the PEG triblock polyurethane shell material can provide a second phase transition temperature at 61.7°C, and has a higher phase change enthalpy and better thermal cycling stability (ΔH m =165.3J / g, ΔH m-500 =158.7 J / g)

[0137] The present application has been described in detail above. Specific examples have been used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is intended only to facilitate understanding of the present application and its core concepts. It should be noted that, without departing from the principles of the present application, a number of improvements and modifications may be made to the present application by a person skilled in the art, and such improvements and modifications shall fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing phase-change microcapsules with two-stage temperature control capability, characterized in that: The following steps are involved: S1. Add 100 parts of methyl stearate, 20-40 parts of polycarbonate diol, 15-30 parts of isophorone diisocyanate, and 1-5 parts of thermally conductive filler into a four-necked flask, stir at 80°C and 500 rpm under a nitrogen atmosphere, and prepolymerize for 2 hours to prepare an oil phase system; S2. Disperse 5-10 parts of emulsifier in 150 ml of deionized water at 80°C, stir evenly and set aside; S3. Add the oil phase system dropwise to the emulsifier, stir at 80°C with an emulsifier at 8000 rpm until a white emulsion is produced; S4. Slowly add 50 to 70 parts of polyethylene glycol to the emulsion, and continue stirring at 80° C. and 500 rpm for 4 hours to obtain a triblock copolymer; S5. Add 0.5 to 1 part of a crosslinking agent to the triblock copolymer at room temperature, stir at 500 rpm until uniformly dispersed, and then place in an oven at 60°C for 6 hours; S6. After the above product is dried, it is washed with water, washed with alcohol, and filtered to obtain phase change microcapsules with two-stage temperature control capabilities.

2. The method for preparing phase-change microcapsules with two-stage temperature control capability according to claim 1, characterized in that: The melting point of the methyl stearate is 38-44°C, and the density at 25°C is 0.86 g / cm 3 .

3. The method for preparing phase-change microcapsules with two-stage temperature control capability according to claim 1, characterized in that: The polyethylene glycol is one of PEG-4000, PEG-6000, PEG-8000, and PEG-10000, or a combination of two or more thereof.

4. The method for preparing phase-change microcapsules with two-stage temperature control capability according to claim 1, characterized in that: The polycarbonate diol has a number average molecular weight of 800 g / mol, a viscosity of 600 to 1200 mPa·s, and an OH value of 200 to 250 mgKOH / g.

5. The method for preparing phase-change microcapsules with two-stage temperature control capability according to claim 1, characterized in that: The isophorone diisocyanate has a molecular weight of 222.32 g / mol, a viscosity of 10 mPa·s, and an isocyanate content of 37.5 to 45 wt %.

6. The method for preparing phase-change microcapsules with two-stage temperature control capability according to claim 1, characterized in that: The emulsifier is one or a combination of two or more of polyvinyl alcohol, sodium lauryl sulfate, and cetyltrimethylammonium bromide.

7. The method for preparing phase-change microcapsules with two-stage temperature control capability according to claim 1, characterized in that: The thermal conductive filler is one of aluminum nitride, boron nitride, and aluminum oxide, or a combination of two or more.

8. The method for preparing phase-change microcapsules with two-stage temperature control capability according to claim 1, characterized in that: The cross-linking agent is one or a combination of two or more of trimethylolpropane, triethanolamine and melamine.

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