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

Abstract

The invention relates to the technical field of multifunctional phase-change materials, in particular to a phase-change microcapsule with two-stage temperature control capacity and a preparation method of the phase-change microcapsule. The phase change microcapsule disclosed by the invention comprises the following components in parts by weight: 100 parts of methyl stearate (MS); 50 to 70 parts of polyethylene glycol (PEG); 20 to 40 parts of polycarbonate diol (PCDL); 15 to 30 parts of isophorone diisocyanate (IPDI); 5-10 parts of an emulsifier; 1-5 parts of a heat-conducting filler; and 0.5-1 part of a cross-linking agent. The phase change microcapsule takes MS as a core and triblock polyurethane consisting of IPDI, PCDL and PEG as a shell, and is endowed with two-stage temperature control capability, so that the phase change microcapsule has relatively high 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, as an ideal heat storage medium, can release or store a large amount of latent heat during isothermal phase change, thereby achieving the purpose of temperature control. However, the solid-liquid phase transition will inevitably lead to leakage of phase change materials during use.

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

[0004] The phase-change microcapsules obtained by the above method have only one phase-change temperature, which cannot meet the requirements of segmented temperature control for some products. At the same time, the 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 ability, 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 of PEG-4000, PEG-6000, PEG-8000, or a combination of two or more thereof.

[0009] Preferably, the number average molecular weight of the PCDL is 800 g / mol, the viscosity is 600 to 1200 mPa·s, and the OH value is 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 above-mentioned 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, stir at 80°C and 500 r / min under nitrogen atmosphere, and prepolymerize for 2 h to prepare an oil phase system;

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

[0017] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0018] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

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

[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 37.5-45 wt %.

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

[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 in the present invention have two-stage temperature control capabilities and are prepared by interfacial polymerization. The phase change microcapsules use MS as the core for the first phase change, and use polyurethane composed of IPDI, PCDL, and PEG as the shell to encapsulate MS. Among them, the two-block polyurethane generated by IPDI and PCDL has heat resistance and hydrolysis resistance due to the presence of carbonate groups. The introduction of PEG in the shell also gives the shell material the ability of the second phase change. The final product of the present invention has two-stage temperature control capabilities, and also has good thermal properties and thermal cycle stability.

[0029] Performance test of phase change microcapsules

[0030] The thermal properties were tested using a differential scanning calorimeter. The test method was to characterize the thermal properties of the material in the temperature range of 0 to 80°C under a nitrogen atmosphere, with a heating rate of 10°C / min.

[0031] The cyclic stability is tested using a temperature-controlled heating table. The temperature-controlled heating table consists of an intelligent temperature control box MY803-H and a 1800W cast aluminum heating plate (dimensions: 300×200×20mm). The test method is to place the sample on the heating table, raise the temperature of the heating table to 80°C for 30 minutes through program temperature control, and then cool it to 30°C for 30 minutes, repeating this process for 500 cycles, and finally analyzing its thermal properties using a differential scanning calorimeter.

[0032] The thermal conductivity was tested using a thermal conductivity meter TC3000E. The test method was to mold the sample into a 30mm×30mm×5mm sample, then press the sample onto the sensor with a 500g weight, and after thermal equilibrium, test each sample 5 times, and take the average value of the final result.

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

[0034] [Example 1]

[0035] The present 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 microcapsule with two-stage temperature control capability in this embodiment comprises the following steps:

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

[0038] S2. Disperse polyvinyl alcohol in 150 ml of deionized water, stir evenly at 80°C for later use;

[0039] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0040] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

[0041] S5, adding trimethylolpropane to the triblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in an oven at 60° C. to react for 6 hours;

[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] The present 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 dodecyl sulfate; 3 parts of aluminum oxide; and 0.7 parts of melamine.

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

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

[0048] S2. Disperse sodium dodecyl sulfate in 150 ml of deionized water, stir evenly at 80° C. for later use;

[0049] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0050] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

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

[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] The present embodiment provides a phase change microcapsule with two-stage temperature control capability, comprising the following components in parts 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 microcapsule with two-stage temperature control capability in this embodiment comprises the following steps:

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

[0058] S2, dispersing cetyltrimethylammonium bromide in 150 ml of deionized water, stirring evenly at 80° C. for later use;

[0059] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0060] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

[0061] S5, adding triethanolamine to the above triblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in an oven at 60° C. to react for 6 hours;

[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] The present 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; 1 part of boron nitride; and 0.7 parts of trimethylolpropane.

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

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

[0068] S2. Disperse polyvinyl alcohol in 150 ml of deionized water, stir evenly at 80°C for later use;

[0069] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0070] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

[0071] S5, adding trimethylolpropane to the triblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in an oven at 60° C. to react for 6 hours;

[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] The present 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 microcapsule with two-stage temperature control capability in this embodiment comprises the following steps:

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

[0078] S2. Disperse polyvinyl alcohol in 150 ml of deionized water, stir evenly at 80°C for later use;

[0079] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0080] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

[0081] S5, adding trimethylolpropane to the triblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in an oven at 60° C. to react for 6 hours;

[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] The present 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 0.5 parts of trimethylolpropane.

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

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

[0088] S2. Disperse polyvinyl alcohol in 150 ml of deionized water, stir evenly at 80°C for later use;

[0089] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0090] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

[0091] S5, adding trimethylolpropane to the triblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in an oven at 60° C. to react for 6 hours;

[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] The present 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 microcapsule with two-stage temperature control capability in this embodiment comprises the following steps:

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

[0098] S2. Disperse polyvinyl alcohol in 150 ml of deionized water, stir evenly at 80°C for later use;

[0099] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0100] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

[0101] S5, adding trimethylolpropane to the triblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in an oven at 60° C. to react for 6 hours;

[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] The present 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 microcapsule with two-stage temperature control capability in this embodiment comprises the following steps:

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

[0108] S2. Disperse polyvinyl alcohol in 150 ml of deionized water, stir evenly at 80°C for later use;

[0109] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0110] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer;

[0111] S5, adding trimethylolpropane to the triblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in an oven at 60° C. to react for 6 hours;

[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 microcapsule with two-stage temperature control capability in this embodiment comprises the following steps:

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

[0118] S2. Disperse polyvinyl alcohol in 150 ml of deionized water, stir evenly at 80°C for later use;

[0119] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

[0120] S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h 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 microcapsule with two-stage temperature control capability in this embodiment comprises the following steps:

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

[0127] S2. Disperse polyvinyl alcohol in 150 ml of deionized water, stir evenly at 80°C for later use;

[0128] S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced;

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

[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 Emulsifier 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 Example 1, the addition of thermal conductive filler in Example 2 can significantly increase the thermal conductivity of the phase change microcapsules, and the thermal conductivity coefficient is 1.18W / m·K, which is 70.3% higher than that of Example 1. Compared with Example 2, the addition of crosslinking agent in Example 2 affects the encapsulation effect of the MS core. The shell without crosslinking agent has poor compactness and exhibits low phase change enthalpy. Compared with Example 3, the construction of PEG triblock polyurethane shell material in Example 2 can provide a second phase change 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 is described in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application and its core ideas. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A phase change microcapsule with two-stage temperature control capability, characterized in that: The invention comprises the following components in parts 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.

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

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

4. The phase-change microcapsule with two-stage temperature control capability according to claim 1, characterized in that: 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.

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

6. The phase-change microcapsule 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 phase-change microcapsule 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 thereof.

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

9. A method for preparing a phase-change microcapsule having two-stage temperature control capability, characterized in that: The following steps are involved: S1. Add MS, PCDL, IPDI and thermal conductive filler into a four-necked flask, stir at 80°C and 500 r / min under nitrogen atmosphere, and prepolymerize for 2 h to prepare an oil phase system; S2. Disperse the emulsifier in 150 ml of deionized water, stir evenly at 80°C for later use; S3, adding the oil phase system dropwise into the emulsifier, stirring at 80°C with an emulsifier at 8000 r / min until a white emulsion is produced; S4, slowly adding PEG into the emulsion, stirring and reacting at 80°C and 500r / min for 4h to obtain a triblock copolymer; S5, adding the crosslinking agent to the triblock copolymer at room temperature, stirring at 500 r / min until uniformly dispersed, and then placing in an oven at 60° C. to react 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.

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