Polyurea-polyacrylate double-layer shell material phase change microcapsule and preparation method thereof

Abstract

The invention relates to the technical field of phase change microcapsules, in particular to a polyurea / polyacrylate double-layer shell material phase change microcapsule and a preparation method thereof. The microcapsule sequentially comprises a phase change material core material, a polyacrylate shell material and a polyurea shell material from inside to outside, and is prepared from the following raw materials: a polyisocyanate monomer, an acrylate monomer, an acrylate functional monomer, an acrylate cross-linking agent, a chain extender, an initiator, a surfactant, a phase change material and water. According to the invention, polyurea interfacial polymerization and polyacrylate suspension polymerization are combined to form a double-layer shell material for coating to prepare the phase change microcapsule, so that the phase change microcapsule has excellent sealing property, durability and high enthalpy value performance.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change microcapsules, and more specifically, to a polyurea / polyacrylate double-layer shell material phase change microcapsule and a preparation method thereof. Background Art

[0002] Microcapsule technology is a technology that uses film-forming materials to encapsulate solids or liquids into particles with core-shell structures. The resulting particles are called microcapsules. Phase change materials are dispersed into spherical small particles, and then a layer of shell materials with stable performance is encapsulated on the surface to finally form phase change microcapsules. It has been widely used in packaging, aerospace, construction, textiles, medicine, electronics and other material fields. However, in actual use, the phase change materials coated by phase change microcapsules have leakage and phase separation problems after phase change cycles. After leakage, the application environment may be corroded, which puts higher requirements on the performance and quality of phase change microcapsules. At present, the direction of more research is phase change microcapsules with polymers as shell materials. Such polymer shell materials mainly include polymers such as melamine / urea-formaldehyde / phenolic formaldehyde / polyurea / polyurethane and polyacrylate. These polymers have their own advantages and disadvantages. Melamine / urea-formaldehyde / phenolic formaldehyde shell materials are formed by interface deposition. In the preparation process, the shell materials are prone to adhesion and agglomeration, causing problems such as explosion and agglomeration, resulting in poor quality of microcapsule products, which are difficult to achieve stable process, and the formaldehyde release problem also limits its application.

[0003] Chinese invention patent CN107903877A relates to a method for preparing polyurea resin phase change microcapsules, and the obtained polyurea-coated n-octadecane phase change microcapsules have a thermal enthalpy of 95.81 J / g; polyacrylate shell materials are mainly suspended polymerization, and the process operation is relatively convenient and simple. Chinese invention patent CN117821025B relates to a phase change microcapsule and a preparation method thereof, and a high-strength phase change microcapsule with polymethyl methacrylate as the shell material is prepared, with a low coverage rate and a thermal enthalpy value of no more than 140 J / g; the sealing of these two types of shell material phase change microcapsules is poor, and thicker shell materials are often required to improve the leakage problem, which makes the coverage rate and thermal enthalpy value of the phase change microcapsules generally low. It is difficult to obtain phase change microcapsules with excellent applicability using the above-mentioned simple polymer shell materials, and composite shell material technology provides a solution. Chinese invention patent CN116920737B relates to a silicon dioxide-polyurethane composite phase change microcapsule and a preparation method thereof, and the obtained n-octadecane phase change microcapsule has a thermal enthalpy value of up to about 180 J / g; Chinese invention patent CN113881404B relates to an organic phase change microcapsule with high coverage, high thermal conductivity and high thermal cycle stability and a preparation method thereof, and a modified silicon nitride polymethyl methacrylate composite phase change microcapsule is obtained, and the thermal enthalpy value is greater than 200 J / g. This type of modified composite method belongs to organic-inorganic hybrid shell material, which enhances or gives the material extra functions, but the material is not easy, the process is complicated, and the operation is difficult, which is not suitable for industrial application production. Summary of the invention

[0004] The first aspect of the present invention provides a polyurea-polyacrylate double-layer shell material phase change microcapsule, which comprises, from the inside to the outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0005] The phase change microcapsule of the present invention includes, from the inside to the outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material. The phase change microcapsule is prepared by coating a double-layer shell material formed by combining polyurea interfacial polymerization and polyacrylate suspension polymerization, so that the phase change microcapsule has excellent sealing, durability and high enthalpy performance. The first layer (outermost layer) of polyurea shell material ensures that the experiment improves the agglomeration and explosion problems of polyacrylate polymerization, ensures the stability of the experimental process, and provides a layer of acid, alkali and weather resistance protection for the phase change microcapsule; secondly, the second layer of hydrophilic polyacrylate shell material reduces the leakage problem caused by the swelling or penetration of the hydrophobic alkane phase change material core material into the shell material; in this way, the double-layer shell material improves the sealing and durability of the phase change microcapsule.

[0006] The acrylate functional monomer can separate the polyacrylate layer and the polyurea layer and improve the compactness of the microcapsule structure.

[0007] The raw materials for preparing the phase-change microcapsules include: polyisocyanate monomers, acrylate monomers, acrylate functional monomers, acrylate crosslinking agents, chain extenders, initiators, surfactants, phase-change materials and water.

[0008] The polyisocyanate monomer includes one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanate methyl hexanoate, dicyclohexylmethane diisocyanate, and methylcyclohexyl diisocyanate.

[0009] Preferably, the polyisocyanate monomer includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate.

[0010] The acrylate monomer includes monofunctional acrylate, and the monofunctional acrylate includes one or more of acrylonitrile, methacrylonitrile, methyl methacrylate, ethyl methacrylate, methyl acrylate, butyl acrylate, n-butyl methacrylate, amyl methacrylate, isopentyl methacrylate, cyclohexyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, n-nonyl methacrylate, and isononyl acrylate.

[0011] Preferably, the monofunctional acrylate includes one or more of methyl methacrylate, ethyl acrylate and methyl acrylate.

[0012] Preferably, the weight ratio of the polyisocyanate monomer to the acrylate monomer is (5-20):(3-15).

[0013] More preferably, the weight ratio of the polyisocyanate monomer to the acrylate monomer is (6-15):(3-12).

[0014] The phase change material comprises a long-chain alkane phase change material, the general structural formula of which is C n H 2n+2 , where n>10.

[0015] Preferably, n>16.

[0016] Preferably, n is one of 16, 18, 20 and 22.

[0017] More preferably, n is 18 or 20.

[0018] The acrylate crosslinking agent includes a multifunctional acrylate, and the multifunctional acrylate includes one or more of ethylene glycol dimethacrylate, ethylene glycol diacrylate, dipropylene glycol dimethacrylate, butanediol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol diacrylate, 3-methyl 1,5-pentanediol diacrylate, hexanediol diacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, ethoxylated bisphenol A-diacrylate, propoxylated neopentyl glycol diacrylate, propoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and dipentaerythritol hexaacrylate.

[0019] Preferably, the acrylate crosslinking agent includes one or more of ethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, and trimethylolpropane triacrylate.

[0020] The acrylate functional monomer includes a compound containing a carbon-carbon double bond, and the compound containing a carbon-carbon double bond includes one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0021] Preferably, the acrylate functional monomer includes one or more of methacrylic acid, acrylic acid, and hydroxyethyl methacrylate.

[0022] The initiator includes one or more of toluoyl peroxide, lauroyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, azobisisobutyronitrile, azobisisoheptylnitrile, and azoisobutylcyanoformamide.

[0023] Preferably, the initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and toluoyl peroxide.

[0024] The amine chain extender includes one or more of ethylenediamine, hexamethylenediamine, triethylenediamine, tetraethylenetriamine, polyethyleneimine and the like.

[0025] Preferably, the amine chain extender includes one or more of ethylenediamine, hexamethylenediamine, and diethylenetriamine.

[0026] Preferably, the glass transition temperature of the acrylate monomer is greater than the melting temperature of the phase change material.

[0027] The surfactant includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, ammonium dodecylbenzene sulfonate, alkyl dimethyl sulfoethyl betaine, alkyl dimethyl sulfopropyl betaine, alkyl dimethyl hydroxypropyl phosphate betaine, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and polystyrene-maleic anhydride copolymer.

[0028] Preferably, the surfactant includes one or more of sodium dodecyl sulfate, polyethylene glycol, sodium dodecylbenzene sulfonate, and polystyrene-maleic anhydride copolymer.

[0029] Preferably, the glass transition temperature of the acrylate monomer is greater than the melting temperature of the phase change material.

[0030] The second aspect of the present invention provides a method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule, comprising the following steps:

[0031] S1, mixing polyisocyanate monomers, acrylate monomers, acrylate functional monomers, acrylate crosslinking agents, initiators, and phase change materials, and stirring evenly to form an oil phase;

[0032] S2, adding a surfactant into water and stirring evenly to form an aqueous phase;

[0033] S3, adding the water phase to the oil phase, stirring at high speed to homogenize and emulsify, to form an emulsion;

[0034] S4, adding an aqueous solution of an amine chain extender to the emulsion, stirring evenly, and reacting to form a polyurea shell phase change microcapsule suspension;

[0035] S5, heating the suspension to react in the polyurea shell to form a polyacrylate shell, thereby obtaining a polyurea-polyacrylate double-layer shell material phase change microcapsule suspension;

[0036] S6, filtering, washing and drying the polyurea-polyacrylate double-layer shell phase change microcapsule suspension to obtain.

[0037] An interpenetrating network structure can be formed at the interface between the polyurea shell material and the polyacrylate shell material, thereby further improving the air tightness of the material.

[0038] The concentration of the surfactant in the water phase is 0.5-1.5 wt %.

[0039] Preferably, the concentration of the surfactant in the aqueous phase is 0.6-1.2 wt %.

[0040] The concentration of the amine chain extender in the aqueous solution of the amine chain extender is 1-15 wt %.

[0041] Preferably, the concentration of the amine chain extender in the aqueous solution of the amine chain extender is 1-10 wt %.

[0042] The amount of the initiator added to the oil phase is 0.05-2 wt %.

[0043] Preferably, the amount of the initiator added to the oil phase is 0.08-0.2 wt %.

[0044] The amount of the acrylic acid ester functional monomer added to the oil phase is 0.1-10 wt %.

[0045] Preferably, the amount of acrylate functional monomer added to the oil phase is 0.1-4wt%

[0046] The amount of the acrylic acid ester monomer added to the oil phase is 2-20 wt %.

[0047] Preferably, the amount of acrylate monomer added to the oil phase is 3-12 wt %.

[0048] The amount of polyisocyanate monomer added to the oil phase is 5-30 wt %.

[0049] Preferably, the amount of polyisocyanate monomer added to the oil phase is 6-15wt%

[0050] The amount of the acrylic ester crosslinking agent added to the oil phase is 0.1-10 wt %.

[0051] Preferably, the amount of the acrylate crosslinking agent added to the oil phase is 0.2-1.2 wt %.

[0052] The reaction temperature in S4 is greater than 40°C, and the reaction temperature in S5 is greater than 60°C.

[0053] Preferably, the reaction temperature in S5 is at least 10° C. higher than the reaction temperature in S4.

[0054] More preferably, the reaction temperature in S4 is 40-50°C, and the reaction temperature in S5 is 60-80°C.

[0055] The dropping rate is 1.0-10 mL / min.

[0056] Preferably, the dripping rate is 1.0-8.0 mL / min.

[0057] Further preferably, the dropping rate is 1.0-5.0 mL / min.

[0058] The stirring rate of the homogenizing and emulsifying is 3000-10000 rpm.

[0059] Preferably, the stirring rate of the homogenizing emulsification is 4000-8000 rpm.

[0060] Beneficial Effects

[0061] 1. The phase-change microcapsules of the present invention have readily available raw materials for preparation, simple process operation, and are easy to realize industrial production.

[0062] 2. The phase change microcapsules of the present invention include, from the inside to the outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material. The phase change microcapsules are prepared by combining polyurea interfacial polymerization and polyacrylate suspension polymerization to form a double-layer shell material coating, so that the phase change microcapsules have excellent sealing, durability and high enthalpy performance.

[0063] 3. The glass transition temperature of the acrylate monomer is greater than the melting temperature of the phase change material, which further improves the coating barrier effect of the acrylate shell material on the phase change material, and the coating efficiency is greater than 97%.

[0064] 4. The weight ratio of polyisocyanate monomer to acrylate monomer is (5-20):(3-15), and the enthalpy value of the prepared microcapsules can reach 200 J / g.

[0065] 5. The reaction temperature in S4 is 40-50°C, and the reaction temperature in S5 is 60-80°C. The prepared microcapsules have a small loss of thermal enthalpy after 500 hot and cold cycles, and the cycle durability is >97%, which shows excellent cycle durability.

[0066] 6. The 5% thermal decomposition delay temperature of the phase change microcapsules prepared by the present invention is greater than 95°C, and the decomposition temperature is higher than

[0067] 220℃, with excellent sealing performance, meeting practical application needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is an electron microscope image of the phase change microcapsule prepared in Example 1.

[0069] Figure 2 This is a thermal cycle curve diagram of the phase change microcapsules prepared in Example 1.

[0070] Figure 3 The thermogravimetric curves of the phase change microcapsules and phase change materials prepared in Example 1 are shown. DETAILED DESCRIPTION

[0071] The present invention provides a method for preparing high enthalpy and high durability phase change microcapsules by coating phase change materials with double-layer shell materials. The phase change microcapsules are prepared by coating double-layer shell materials formed by combining polyurea interfacial polymerization and polyacrylate suspension polymerization, so that the phase change microcapsules have excellent sealing, durability and high enthalpy performance.

[0072] Example 1

[0073] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0074] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomer (toluene diisocyanate), acrylate monomer (methyl methacrylate), acrylate functional monomer (methacrylic acid), acrylate crosslinking agent (ethylene glycol dimethacrylate), chain extender (ethylenediamine), initiator (azobisisobutyronitrile), surfactant (sodium dodecyl sulfate), phase change material (n-octadecane) and water.

[0075] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0076] (1) 10 g of toluene diisocyanate, 8.5 g of methyl methacrylate, 1.0 g of methacrylic acid, 0.5 g of ethylene glycol dimethacrylate, and 0.1 g of azobisisobutyronitrile were added in sequence, mixed and stirred, and then 80 g of n-octadecane was added and stirred evenly to obtain an oil phase.

[0077] (2) Prepare 300 g of 0.6 wt% sodium dodecyl sulfate aqueous solution as the aqueous phase.

[0078] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 8000 rpm to obtain a stable emulsion, while maintaining the temperature of the emulsion system at 40°C.

[0079] (4) Add 20 mL of a 10 wt% aqueous solution of ethylenediamine to the emulsion in (3) at a dropping rate of 2.0 mL / min. After the addition is complete, heat the mixture at 40° C. for 2 h to obtain a microcapsule pre-dispersion solution.

[0080] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 70°C and kept warm for 4 hours, with a heating rate of 20°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell material phase change microcapsule aqueous suspension.

[0081] (6) filtering, washing, and drying the polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) to finally obtain a phase change microcapsule powder ( Figure 1 ), named F-1.

[0082] Example 2

[0083] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0084] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomer (isophorone diisocyanate), acrylate monomer (methyl methacrylate), acrylate functional monomer (acrylic acid), acrylate crosslinking agent (ethylene glycol dimethacrylate), chain extender (ethylenediamine), initiator (azobisisoheptonitrile), surfactant (sodium dodecyl sulfate), phase change material (n-octadecane) and water.

[0085] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0086] (1) 12 g of isophorone diisocyanate, 6.0 g of methyl methacrylate, 1.0 g of acrylic acid, 1.0 g of ethylene glycol dimethacrylate, and 0.1 g of azobisisoheptane were added in sequence, mixed and stirred, and then 80 g of n-octadecane was added and stirred evenly to obtain an oil phase.

[0087] (2) Prepare 300 g of 0.8 wt% sodium dodecyl sulfate aqueous solution as the aqueous phase.

[0088] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 6000 rpm to obtain a stable emulsion, while maintaining the temperature of the emulsion system at 40°C.

[0089] (4) Add 25 mL of a 4.0 wt% aqueous solution of ethylenediamine to the emulsion in (3) at a dropping rate of 2.0 mL / min. After the addition is complete, heat the mixture at 40° C. for 2 h to obtain a microcapsule pre-dispersion solution.

[0090] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 60°C and kept warm for 6 hours, with a heating rate of 10°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell material phase change microcapsule aqueous suspension.

[0091] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-2.

[0092] Example 3

[0093] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0094] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomer (hexamethylene diisocyanate), acrylate monomer (methyl methacrylate), acrylate functional monomer (hydroxyethyl methacrylate), acrylate crosslinking agent (dipropylene glycol dimethacrylate), chain extender (hexamethylenediamine), initiator (azobisisoheptonitrile), surfactant (sodium dodecylbenzene sulfonate), phase change material (n-eicosane) and water.

[0095] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0096] (1) 10 g of hexamethylene diisocyanate, 12 g of methyl methacrylate, 2.0 g of hydroxyethyl methacrylate, 1.0 g of dipropylene glycol dimethacrylate, and 0.1 g of azobisisoheptane were added in sequence, mixed and stirred, and then 75 g of n-eicosane was added and stirred evenly to obtain an oil phase.

[0097] (2) Prepare 300 g of 0.8 wt % sodium dodecylbenzene sulfonate aqueous solution as the aqueous phase.

[0098] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 8000 rpm to obtain a stable emulsion, while maintaining the temperature of the emulsion system at 50°C.

[0099] (4) Add 20 mL of a 1.5 wt% aqueous solution of hexamethylenediamine to the emulsion in (3) at a dropping rate of 5.0 mL / min. After the dropping is completed, heat the mixture at 50° C. for 2 h to obtain a microcapsule pre-dispersion solution.

[0100] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 60°C and kept warm for 8 hours, with a heating rate of 10°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell material phase change microcapsule aqueous suspension.

[0101] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-3.

[0102] Example 4

[0103] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0104] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomer (diphenylmethane diisocyanate), acrylate monomer (methyl methacrylate), acrylate functional monomer (hydroxyethyl methacrylate), acrylate crosslinking agent (trimethylolpropane triacrylate), chain extender (hexamethylenediamine), initiator (azobisisobutyronitrile), surfactant (polyethylene glycol), phase change material (n-eicosane) and water.

[0105] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0106] (1) 12 g of diphenylmethane diisocyanate, 10 g of methyl methacrylate, 2.0 g of hydroxyethyl methacrylate, 1.0 g of trimethylolpropane triacrylate, and 0.15 g of azobisisobutyronitrile were added in sequence, mixed and stirred, and then 75 g of n-eicosane was added and stirred evenly to obtain an oil phase.

[0107] (2) Prepare 300 g of 1.0 wt% polyethylene glycol aqueous solution as the aqueous phase.

[0108] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 4000 rpm to obtain a stable emulsion, and maintain the temperature of the emulsion system at 50°C.

[0109] (4) Add 10 mL of a 2.0 wt% aqueous solution of hexamethylenediamine to the emulsion in (3) at a dropping rate of 4.0 mL / min. After the addition is complete, heat the mixture at 50° C. for 3 h to obtain a microcapsule pre-dispersion solution.

[0110] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 70°C and kept warm for 4 hours, with a heating rate of 20°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell material phase change microcapsule aqueous suspension.

[0111] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-4.

[0112] Example 5

[0113] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0114] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomers (hexamethylene diisocyanate and isophorone diisocyanate), acrylate monomers (methyl methacrylate), acrylate functional monomers (hydroxyethyl methacrylate), acrylate crosslinking agents (trimethylolpropane triacrylate), chain extenders (diethylenetriamine), initiators (azobisisobutyronitrile), surfactants (sodium dodecylbenzene sulfonate), phase change materials (n-eicosane) and water.

[0115] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0116] (1) 10 g of hexamethylene diisocyanate, 5 g of isophorone diisocyanate, 10 g of methyl methacrylate, 4.0 g of hydroxyethyl methacrylate, 1.0 g of trimethylolpropane triacrylate, and 0.1 g of azobisisobutyronitrile were added in sequence, mixed and stirred, and then 70 g of n-eicosane was added and stirred evenly to obtain an oil phase.

[0117] (2) Prepare 300 g of 1.2 wt% sodium dodecylbenzene sulfonate aqueous solution as the aqueous phase.

[0118] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 5000 rpm to obtain a stable emulsion, and maintain the temperature of the emulsion system at 50°C.

[0119] (4) Add 10 mL of a 2.0 wt% aqueous solution of diethylenetriamine to the emulsion in (3) at a dropping rate of 2.0 mL / min. After the addition is complete, heat the mixture at 50° C. for 2 h to obtain a microcapsule pre-dispersion solution.

[0120] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 70°C and kept warm for 6 hours, with a heating rate of 20°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell material phase change microcapsule aqueous suspension.

[0121] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-5.

[0122] Example 6

[0123] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0124] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomers (hexamethylene diisocyanate and isophorone diisocyanate), acrylate monomers (methyl methacrylate), acrylate functional monomers (hydroxyethyl methacrylate), acrylate crosslinking agents (trimethylolpropane triacrylate), chain extenders (diethylenetriamine), initiators (azobisisobutyronitrile), surfactants (polystyrene-maleic anhydride copolymers), phase change materials (n-eicosane) and water.

[0125] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0126] (1) 5 g of hexamethylene diisocyanate, 5 g of isophorone diisocyanate, 8.0 g of methyl methacrylate, 1.0 g of hydroxyethyl methacrylate, 1.0 g of trimethylolpropane triacrylate, and 0.15 g of azobisisobutyronitrile were added in sequence, mixed and stirred, and then 80 g of n-eicosane was added and stirred evenly to obtain an oil phase.

[0127] (2) Prepare 300 g of a 0.6 wt% polystyrene-maleic anhydride copolymer aqueous solution as the aqueous phase.

[0128] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 6000 rpm to obtain a stable emulsion, and maintain the temperature of the emulsion system at 50°C.

[0129] (4) Add 15 mL of a 1.2 wt% aqueous solution of diethylenetriamine to the emulsion in (3) at a dropping rate of 1.0 mL / min. After the addition is complete, heat the mixture at 50° C. for 2 h to obtain a microcapsule pre-dispersion solution.

[0130] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 70°C and kept warm for 6 hours, with a heating rate of 20°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell material phase change microcapsule aqueous suspension.

[0131] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-6.

[0132] Example 7

[0133] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0134] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomers (hexamethylene diisocyanate and isophorone diisocyanate), acrylate monomers (methyl methacrylate), acrylate functional monomers (methacrylic acid), acrylate crosslinking agents (trimethylolpropane triacrylate), chain extenders (diethylenetriamine), initiators (azobisisobutyronitrile), surfactants (sodium dodecylbenzene sulfonate), phase change materials (n-octadecane) and water.

[0135] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0136] (1) 8 g of hexamethylene diisocyanate, 4 g of isophorone diisocyanate, 7.0 g of methyl methacrylate, 0.6 g of methacrylic acid, 0.4 g of trimethylolpropane triacrylate, and 0.15 g of azobisisobutyronitrile were added in sequence, mixed and stirred, and then 80 g of n-octadecane was added and stirred evenly to obtain an oil phase.

[0137] (2) Prepare 300 g of 1.0 wt% sodium dodecylbenzene sulfonate aqueous solution as the aqueous phase.

[0138] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 5000 rpm to obtain a stable emulsion, and maintain the temperature of the emulsion system at 50°C.

[0139] (4) Add 10 mL of a 3.0 wt% aqueous solution of diethylenetriamine to the emulsion in (3) at a dropping rate of 2.0 mL / min. After the addition is complete, heat the mixture at 50° C. for 2 h to obtain a microcapsule pre-dispersion solution.

[0140] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 70°C and kept warm for 6 hours, with a heating rate of 20°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell material phase change microcapsule aqueous suspension.

[0141] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-7.

[0142] Example 8

[0143] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0144] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomer (isophorone diisocyanate), acrylate monomer (methyl methacrylate and methyl acrylate), acrylate functional monomer (hydroxyethyl methacrylate), acrylate crosslinking agent (ethylene glycol dimethacrylate), chain extender (hexamethylenediamine), initiator (toluoyl peroxide), surfactant (sodium dodecylbenzene sulfonate), phase change material (n-octadecane) and water.

[0145] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0146] (1) 9 g of isophorone diisocyanate, 4.4 g of methyl methacrylate, 0.4 g of methyl acrylate, 0.4 g of hydroxyethyl methacrylate, 0.4 g of ethylene glycol dimethacrylate, 0.4 g of trimethylolpropane triacrylate, and 0.2 g of toluoyl peroxide were added in sequence, mixed and stirred, and then 85 g of n-octadecane was added and stirred evenly to obtain an oil phase.

[0147] (2) Prepare 300 g of 1.2 wt% sodium dodecylbenzene sulfonate aqueous solution as the aqueous phase.

[0148] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 6000 rpm to obtain a stable emulsion, while maintaining the temperature of the emulsion system at 40°C.

[0149] (4) Add 15 mL of a 2.0 wt% aqueous solution of hexamethylenediamine to the emulsion in (3) at a dropping rate of 1.0 mL / min. After the addition is complete, heat the mixture at 40° C. for 3 h to obtain a microcapsule pre-dispersion solution.

[0150] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 80°C and kept for 4 hours at a heating rate of 20°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension.

[0151] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-8.

[0152] Example 9

[0153] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0154] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomer (isophorone diisocyanate), acrylate monomer (methyl methacrylate and ethyl acrylate), acrylate functional monomer (methacrylic acid), acrylate crosslinking agent (ethylene glycol dimethacrylate), chain extender (hexamethylenediamine), initiator (toluoyl peroxide), surfactant (sodium dodecylbenzene sulfonate), phase change material (n-octadecane) and water.

[0155] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0156] (1) 8 g of isophorone diisocyanate, 5.4 g of methyl methacrylate, 0.4 g of ethyl acrylate, 0.2 g of methacrylic acid, 0.6 g of ethylene glycol dimethacrylate, 0.4 g of trimethylolpropane triacrylate, and 0.2 g of toluoyl peroxide were added in sequence, mixed and stirred, and then 85 g of n-octadecane was added and stirred evenly to obtain an oil phase.

[0157] (2) Prepare 300 g of 1.0 wt% sodium dodecylbenzene sulfonate aqueous solution as the aqueous phase.

[0158] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 8000 rpm to obtain a stable emulsion, while maintaining the temperature of the emulsion system at 40°C.

[0159] (4) Add 10 mL of a 2.0 wt% aqueous solution of hexamethylenediamine to the emulsion in (3) at a dropping rate of 2.0 mL / min. After the dropping is completed, heat the mixture at 40° C. for 3 h to obtain a microcapsule pre-dispersion solution.

[0160] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 80°C and kept for 4 hours at a heating rate of 20°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension.

[0161] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-9.

[0162] Example 10

[0163] A polyurea-polyacrylate double-layer shell material phase change microcapsule comprises, from inside to outside, a phase change material core material, a polyacrylate shell material and a polyurea shell material.

[0164] The raw materials for preparing the phase change microcapsules are: polyisocyanate monomers (hexamethylene diisocyanate and isophorone diisocyanate), acrylate monomers (methyl methacrylate and ethyl acrylate), acrylate functional monomers (methacrylic acid), acrylate crosslinking agents (ethylene glycol dimethacrylate), chain extenders (diethylenetriamine), initiators (toluoyl peroxide), surfactants (sodium dodecylbenzene sulfonate), phase change materials (n-octadecane) and water.

[0165] A method for preparing a polyurea-polyacrylate double-layer shell material phase change microcapsule comprises the following steps:

[0166] (1) 3 g of hexamethylene diisocyanate, 3 g of isophorone diisocyanate, 3 g of methyl methacrylate, 0.3 g of ethyl acrylate, 0.1 g of methacrylic acid, 0.3 g of ethylene glycol dimethacrylate, 0.3 g of trimethylolpropane triacrylate, and 0.2 g of toluoyl peroxide were added in sequence, mixed and stirred, and then 90 g of n-octadecane was added and stirred evenly to obtain an oil phase.

[0167] (2) Prepare 100 g of a 1.0 wt% aqueous solution of sodium dodecylbenzene sulfonate and 200 g of a 1.0 wt% aqueous solution of polyvinyl alcohol as the aqueous phase.

[0168] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 6000 rpm to obtain a stable emulsion, while maintaining the temperature of the emulsion system at 40°C.

[0169] (4) Add 10 mL of a 1.0 wt% aqueous solution of diethylenetriamine to the emulsion in (3) at a dropping rate of 2.0 mL / min. After the addition is complete, heat the mixture at 40° C. for 4 h to obtain a microcapsule pre-dispersion solution.

[0170] (5) The reaction temperature of the microcapsule pre-dispersion liquid described in (4) was adjusted to 80°C and kept for 4 hours at a heating rate of 20°C / h. After the reaction was completed, the temperature was cooled to room temperature to obtain a polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension.

[0171] (6) The polyurea / polyacrylate double-layer shell phase change microcapsule aqueous suspension obtained in (5) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named F-10.

[0172] Comparative Example 1

[0173] A phase-change microcapsule, the preparation raw materials of which are: polyisocyanate monomer (toluene diisocyanate), chain extender (ethylenediamine), surfactant (sodium dodecyl sulfate), phase-change material (n-octadecane) and water.

[0174] A method for preparing phase change microcapsules comprises the following steps:

[0175] (1) 15 g of toluene diisocyanate and then 85 g of n-octadecane were added in sequence and stirred evenly to obtain an oil phase.

[0176] (2) Prepare 300 g of 0.6 wt% sodium dodecyl sulfate aqueous solution as the aqueous phase.

[0177] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly for emulsification at an emulsification rate of 6000 rpm to obtain a stable emulsion, while maintaining the temperature of the emulsion system at 40°C.

[0178] (4) Add 20 mL of a 10 wt% aqueous solution of ethylenediamine to the emulsion described in (3) at a dropping rate of 2.0 mL / min. After the dropping is completed, the reaction temperature is raised to 40° C. and kept for 4 h, and then raised to 60° C. and kept for 4 h to obtain an aqueous suspension of polyurea shell phase change microcapsules.

[0179] (5) The aqueous suspension of the polyurea shell phase change microcapsules obtained in (4) was filtered, washed, and dried to finally obtain a phase change microcapsule powder, which was named EX-1.

[0180] Comparative Example 2

[0181] The raw materials for preparing a phase change material are: acrylate monomer (methyl methacrylate), acrylate functional monomer (methacrylic acid), acrylate crosslinking agent (ethylene glycol dimethacrylate), initiator (), surfactant (sodium dodecyl sulfate), phase change material (n-octadecane) and water.

[0182] A method for preparing a phase change material comprises the following steps:

[0183] (1) 12 g of methyl methacrylate, 1.0 g of methacrylic acid, 2.0 g of ethylene glycol dimethacrylate, and 0.15 g of azobisisobutyronitrile were added in sequence, mixed and stirred, and then 85 g of n-octadecane was added and stirred evenly to obtain an oil phase.

[0184] (2) Prepare 300 g of 0.6 wt% sodium dodecyl sulfate aqueous solution as the aqueous phase.

[0185] (3) Add the aqueous phase described in (2) to the oil phase described in (1), and stir rapidly to emulsify at a rate of 6000 rpm while maintaining the temperature at 40°C to obtain a stable emulsion. Then, increase the temperature to 70°C for 6 hours at a rate of 20°C / h.

[0186] (4) During the reaction process of the above (3), the particles agglomerated and exploded, and phase change microcapsules could not be obtained, resulting in a failed experiment.

[0187] Comparative Example 3

[0188] The specific implementation method is the same as Example 1; the difference is that in Comparative Example 3, 8.5 g of methyl methacrylate in the oil phase preparation in step (1) is replaced by 8.5 g of butyl acrylate, and the parameter processes of subsequent steps (2)(3)(4)(5)(6) remain unchanged, and the phase change microcapsule powder finally obtained is named EX-3.

[0189] Comparative Example 4

[0190] The specific implementation method is the same as Example 1; the difference is that in Comparative Example 4, 8.5 g of methyl methacrylate in the oil phase preparation in step (1) is replaced by 1.0 g of methyl methacrylate and 7.5 g of butyl acrylate, and the parameter processes of subsequent steps (2)(3)(4)(5)(6) remain unchanged, and the phase change microcapsule powder finally obtained is named EX-4.

[0191] Comparative Example 5

[0192] The specific implementation method is the same as Example 1; the difference is that in Comparative Example 5, 1.0 g of methacrylic acid in the oil phase preparation in step (1) is replaced by 1.0 g of methyl methacrylate, and the parameter processes of subsequent steps (2)(3)(4)(5)(6) remain unchanged, and the phase change microcapsule powder finally obtained is named EX-5.

[0193] Comparative Example 6

[0194] The specific implementation method is the same as Example 1; the difference is that in Comparative Example 6, the 10g toluene diisocyanate and 8.5g methyl methacrylate in the oil phase preparation in step (1) are adjusted to 4g toluene diisocyanate and 14.5g methyl methacrylate, and the parameter processes of subsequent steps (2)(3)(4)(5)(6) remain unchanged.

[0195] Comparative Example 7

[0196] The specific implementation is the same as Example 1; the difference is that in Comparative Example 7, the temperature T1 in step (4) is adjusted to 70°C, and the temperature in step (5) is adjusted to 60°C, and the parameter processes of other experimental steps (1)(2)(3)(5)(6) remain unchanged.

[0197] Comparative Example 8

[0198] The specific implementation is the same as Example 1; the difference is that in Comparative Example 8, the temperature T1 in step (4) is adjusted to 60°C, the temperature in step (5) is adjusted to 60°C, and the parameter processes of other experimental steps (1)(2)(3)(5)(6) remain unchanged.

[0199] Comparative Example 9

[0200] The specific implementation method is the same as Example 1; the difference is that in Comparative Example 9, the amount and concentration of the aqueous solution of ethylenediamine in step (4) are adjusted to 10 mL of a 30 wt% aqueous solution of ethylenediamine, and the parameters and processes of other experimental steps (1) (2) (3) (5) (6) remain unchanged.

[0201] Comparative Example 10

[0202] The specific implementation method is the same as Example 1; the difference is that in Comparative Example 10, the dropping speed in step (4) is adjusted to 20 mL / min, and the parameter processes of other experimental steps (1) (2) (3) (5) (6) remain unchanged.

[0203] Performance testing methods and data

[0204] The phase change microcapsules prepared in the examples and comparative examples were subjected to performance tests, and the test data are listed in Table 1-2.

[0205] Among them, n-octadecane: thermal enthalpy value 240.8 J / g, 5% weight loss thermal decomposition temperature 134°C; n-eicosane: thermal enthalpy value 237.7 J / g, 5% weight loss thermal decomposition temperature 157°C.

[0206] The experimental data calculation formula is as follows:

[0207] Coating efficiency = actual thermal enthalpy value / theoretical thermal enthalpy value × 100%;

[0208] Cycle durability = 500th thermal enthalpy value / 1st thermal enthalpy value × 100%;

[0209] Thermal decomposition delay temperature of coating sealing = thermal decomposition temperature of phase change microcapsule loss of 5% - thermal decomposition temperature of phase change material loss of 5%. The larger the thermal decomposition delay temperature value is, the better the coating sealing is.

[0210] Table 1

[0211]

[0212]

[0213] From the data in Table 1, it can be seen that the coating efficiency of the double-layer shell material phase change microcapsules prepared in this application is greater than 97%, which has excellent coating efficiency; moreover, Figure 2 As shown in , after 500 hot and cold cycles, the thermal enthalpy loss is small, and the cycle durability is > 97%, which has excellent cycle durability; Figure 3As shown, the 5% thermal decomposition delay temperature indicates that the phase change material is still covered by the shell material and is difficult to leak after being heated, liquefied and gasified. The higher the delay temperature, the denser the coating. The 5% thermal decomposition delay temperature of the phase change microcapsules prepared by this patent is greater than 95°C, and the decomposition temperature is higher than 220°C. It has excellent sealing properties and meets the needs of practical applications.

[0214] Table 2

[0215]

[0216] It can be seen from the data table 2 that compared with the patent examples 1-10, the cyclic stability of the pure polyurea phase change microcapsules in the comparative example 1 is 88.7% and the 5% thermal decomposition delay temperature is 16°C, and the heat resistance and durability are both low; the comparative example 2 is a pure polyacrylate shell material phase change microcapsule experiment, and no microcapsules can be obtained; the comparative examples 3 and 4 adjust butyl acrylate, and the glass transition temperature Tg is lower than the melting temperature of the phase change material. At this time, the barrier property of the polyacrylate shell material is poor, and the performance of the obtained phase change microcapsules is poor; the comparative example 5 does not contain the acrylate functional monomer, and the barrier property of the phase change material is also poor, and the obtained The cyclic stability of the phase change microcapsules is low; in Comparative Example 6, the ratio of polyurea and polyacrylate shell materials is adjusted, and the polyurea ratio is less than 40%. The viscosity of the system increases during the polymerization process, and the experiment fails; in Comparative Examples 7 and 8, the reaction temperature has reached the reaction temperature of step (5) during step (4), and the polyurea shell material does not react enough to play the role of coating and supporting the emulsion, while the polyacrylate shell material reacts too quickly, the system is unstable and easy to agglomerate, and the experiment fails; in Comparative Examples 9 and 10, the concentration of the amine chain extender and the dripping rate are adjusted, which leads to the polyurea reaction too quickly, resulting in an unstable system, and the experiment fails.

Claims

1. A polyurea-polyacrylate double-layer shell material phase change microcapsule, characterized in that: From the inside to the outside, it includes: a phase change material core material, a polyacrylate shell material and a polyurea shell material.

2. The polyurea-polyacrylate double-layer shell material phase change microcapsule according to claim 1, characterized in that: The raw materials for preparing the phase change microcapsules include: polyisocyanate monomers, acrylate monomers, acrylate functional monomers, acrylate crosslinking agents, chain extenders, initiators, surfactants, phase change materials and water, and the weight ratio of the polyisocyanate monomers to the acrylate monomers is (5-20): (3-15).

3. The polyurea-polyacrylate double-layer shell material phase change microcapsule according to claim 2, characterized in that: The polyisocyanate monomer includes one or more of diphenylmethane diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanate methyl hexanoate, dicyclohexylmethane diisocyanate, and methylcyclohexyl diisocyanate.

4. The polyurea-polyacrylate double-layer shell material phase change microcapsule according to claim 3, characterized in that: The acrylate monomer includes monofunctional acrylate, and the monofunctional acrylate includes one or more of acrylonitrile, methacrylonitrile, methyl methacrylate, ethyl methacrylate, methyl acrylate, butyl acrylate, n-butyl methacrylate, amyl methacrylate, isopentyl methacrylate, cyclohexyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, n-nonyl methacrylate, and isononyl acrylate.

5. The polyurea-polyacrylate double-layer shell material phase change microcapsule according to claim 4, characterized in that: The acrylate crosslinking agent includes a multifunctional acrylate, and the multifunctional acrylate includes one or more of ethylene glycol dimethacrylate, ethylene glycol diacrylate, dipropylene glycol dimethacrylate, butanediol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol diacrylate, 3-methyl 1,5-pentanediol diacrylate, hexanediol diacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, ethoxylated bisphenol A-diacrylate, propoxylated neopentyl glycol diacrylate, propoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and dipentaerythritol hexaacrylate.

6. The polyurea-polyacrylate double-layer shell material phase change microcapsule according to claim 5, characterized in that: The glass transition temperature of the acrylate monomer is greater than the melting temperature of the phase change material.

7. A method for preparing the polyurea-polyacrylate double-layer shell phase change microcapsule according to any one of claims 2 to 6, characterized in that: The following steps are involved: S1, mixing polyisocyanate monomers, acrylate monomers, acrylate functional monomers, acrylate crosslinking agents, initiators, and phase change materials, and stirring evenly to form an oil phase; S2, adding a surfactant into water and stirring evenly to form an aqueous phase; S3, adding the water phase to the oil phase, homogenizing and emulsifying to form an emulsion; S4, adding an aqueous solution of an amine chain extender to the emulsion, stirring evenly, and reacting to form a polyurea shell phase change microcapsule suspension; S5, heating the suspension to react in the polyurea shell to form a polyacrylate shell, thereby obtaining a polyurea-polyacrylate double-layer shell material phase change microcapsule suspension; S6, filtering, washing and drying the polyurea-polyacrylate double-layer shell phase change microcapsule suspension to obtain.

8. The method for preparing the polyurea-polyacrylate double-layer shell phase-change microcapsules according to claim 7, characterized in that: The reaction temperature in S4 is greater than 40°C, the reaction temperature in S5 is greater than 60°C, and the reaction temperature in S5 is at least 10°C higher than the reaction temperature in S4.

9. The method for preparing the polyurea-polyacrylate double-layer shell phase-change microcapsules according to claim 8, characterized in that: The dropping rate is 1.0-10 mL / min.

10. The method for preparing the polyurea-polyacrylate double-layer shell phase change microcapsule according to claim 8 or 9, characterized in that: The stirring rate of the homogenizing and emulsifying is 3000-10000 rpm.

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