A self-flame retardant phosphorus-containing phase change energy storage material microcapsule and its preparation process

Abstract

The present invention relates to the technical field of phase change energy storage materials, and in particular to a self-flame retardant phosphorus-containing phase change energy storage material microcapsule and a preparation process thereof, comprising the following steps: preparing a composite phase change energy storage material, preparing a phosphorus-containing wall layer material, and preparing the self-flame retardant phosphorus-containing phase change energy storage material microcapsule. In the present invention, in the process of preparing the composite phase change energy storage material, paraffin is modified using hydroxylated magnesium oxide-boron nitride powder. Under the synergistic effect of nano-magnesium oxide and nano-boron nitride, the thermal conductivity of the composite phase change energy storage material can be improved; by adding modified ammonium polyphosphate and phosphorus-containing diamine monomer components to the phosphorus-containing wall layer material, the phosphorus-containing wall layer material prepared is used as the wall layer material of the self-flame retardant phosphorus-containing phase change energy storage material microcapsule, which can not only prevent leakage of the composite phase change energy storage material, but also improve the flame retardant properties of the wall layer material of the self-flame retardant phosphorus-containing phase change energy storage material microcapsule.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change energy storage materials, and more particularly to a self-flame retardant phosphorus-containing phase change energy storage material microcapsule and a preparation process thereof. Background Art

[0002] To conserve energy and maximize energy efficiency, phase change energy storage technology, which utilizes the absorption or release of latent heat during phase changes, has gradually gained attention. Organic phase change energy storage materials are a class of organic compounds that can absorb or release large amounts of heat within a specific temperature range while simultaneously switching between solid and liquid states. These materials have the potential to be widely researched and applied to thermal energy storage solutions in various fields, including building energy conservation, solar thermal utilization, and electronic equipment thermal management. Compared to inorganic phase change materials, organic phase change materials generally offer lower costs, better biodegradability, design flexibility, and reduced environmental impact.

[0003] Common organic phase change energy storage materials include fatty acids and their derivatives, waxy substances, polymer phase change materials, etc. However, existing organic phase change energy storage materials generally have problems such as flammability, liquid leakage, and slow thermal conductivity. These problems seriously hinder the practical application of phase change energy storage materials in many fields. At present, the solution to this practical problem is to "fix" the organic phase change energy storage material so that it exhibits the properties of solid-solid phase change materials on a macro scale. This method mainly includes microencapsulation, chemical grafting, block copolymerization and physical adsorption methods. Among them, microencapsulated phase change energy storage materials can overcome many limitations of organic phase change energy storage materials. By coating with surface polymers, the leakage of phase change materials is prevented. In addition, the microcapsules have an extremely high specific surface area, which increases the thermal energy storage capacity and greatly broadens the application range of phase change energy storage materials.

[0004] Furthermore, the frequent occurrence of fires in recent years has posed a significant threat to human life and property safety. This has led to new requirements for the fire resistance of organic phase change energy storage materials in fields such as construction and textiles. Consequently, flame-retardant phase change energy storage materials have become a key research focus in the field. Currently, flame retardant modification of phase change energy storage materials is primarily achieved through the physical addition of flame retardants. However, physically added flame retardants often suffer from poor dispersion in organic phase change energy storage materials, which can easily degrade their thermal conductivity and physical properties. Summary of the Invention

[0005] In response to the shortcomings of organic phase change energy storage materials in the prior art, such as flammability, easy leakage, and slow thermal conductivity, the present invention provides a self-flame retardant phosphorus-containing phase change energy storage material microcapsule and a preparation process thereof, which utilizes a phosphorus-containing compound to form a polymer wall material, and utilizes the polymer wall material to microencapsulate the organic phase change energy storage material, so that the encapsulated organic phase change energy storage material has self-flame retardant properties, can prevent leakage of the organic phase change energy storage material, and improve the thermal conductivity of the organic phase change energy storage material.

[0006] A self-flame retardant phosphorus-containing phase change energy storage material microcapsule, characterized by comprising the following steps:

[0007] S1: Preparation of composite phase change energy storage material, immersing nano-boron nitride in magnesium nitrate solution, and obtaining magnesium oxide-boron nitride powder through impregnation, evaporation concentration, drying, grinding and calcination. The obtained magnesium oxide-boron nitride powder is subjected to hydroxylation modification treatment, and the obtained hydroxylated magnesium oxide-boron nitride powder is mixed with paraffin to obtain modified paraffin. The modified paraffin is mixed with silicate to obtain composite phase change energy storage material;

[0008] S2: Preparation of phosphorus-containing wall layer material: After heating and activating ammonium polyphosphate, melamine is grafted onto the surface of the ammonium polyphosphate to obtain modified ammonium polyphosphate; the modified ammonium polyphosphate, phosphorus-containing diamine monomer, melamine, formaldehyde solution and deionized water are mixed and reacted to obtain the phosphorus-containing wall layer material;

[0009] S3: Preparation of self-flame retardant phosphorus-containing phase change energy storage material microcapsules. Deionized water, emulsifier and composite phase change energy storage material are mixed and stirred to obtain an oil-in-water emulsion. The phosphorus-containing wall layer material is uniformly added dropwise to the oil-in-water emulsion. After heating reaction, the self-flame retardant phosphorus-containing phase change energy storage material microcapsules are obtained after reduced pressure filtration, filter residue collection, washing and drying.

[0010] Furthermore, S1: preparing a composite phase change energy storage material, specifically comprising the following steps:

[0011] S1.1: Immerse nano-boron nitride in a 30% magnesium nitrate solution with a solid-liquid mass ratio of nano-boron nitride to the 30% magnesium nitrate solution of (1-6): (30-100), ultrasonically disperse for 10-15 minutes, and then immerse for 1-3 hours. The impregnated liquid is added to a rotary evaporator and evaporated and concentrated at 50-75°C for 10-20 minutes. Then, the liquid is dried at 100-120°C for 4-8 hours. After drying, it is ground and calcined to obtain magnesium oxide-boron nitride powder;

[0012] S1.2: Add magnesium oxide-boron nitride composite powder to a 20% by mass sodium hydroxide solution, wherein the solid-liquid mass ratio of magnesium oxide-boron nitride composite powder to 20% by mass sodium hydroxide is (1-5):(50-100), and reflux under magnetic stirring in an oil bath at 100-120°C for 15-18 hours. After cooling, filtering, and drying, hydroxylated magnesium oxide-boron nitride powder is obtained;

[0013] S1.3: Add hydroxylated magnesium oxide-boron nitride powder to molten paraffin wax, wherein the amount of hydroxylated magnesium oxide-boron nitride powder added is 3-10% by weight of the paraffin wax, and stir magnetically at 60-65°C for 40-60 minutes at a speed of 500-600 rpm to obtain modified paraffin wax;

[0014] S1.4: Modified paraffin wax and silicate are mixed in a mass ratio of (1-4):(1-2), magnetically stirred at 60-65°C for 60-90 minutes, and then ultrasonically shaken for 20-40 minutes to obtain a phase change material mixture;

[0015] S1.5: Transfer the phase change material mixture to a vacuum pressure sealed glass reactor, reduce the vacuum to 0.01 MPa and maintain the vacuum for 4 to 6 hours to obtain a composite phase change energy storage material.

[0016] Furthermore, in step S1.1, the calcination operation is carried out under a nitrogen atmosphere, the calcination temperature is 380-410° C., and the calcination time is 3-4 hours.

[0017] Furthermore, step S2: preparing the phosphorus-containing wall layer material specifically comprises the following steps:

[0018] S2.1: Activate the ammonium polyphosphate by heating it to 200-280° C. for 1-3 hours, and then prepare the activated ammonium polyphosphate into a dispersed aqueous solution having a mass fraction of 1-3% ammonium polyphosphate;

[0019] S2.2: Add melamine to the ammonium polyphosphate dispersion aqueous solution, the amount of melamine is 3-6% by mass of the activated ammonium polyphosphate, and react at 200-240° C. for 1-3 hours to obtain modified ammonium polyphosphate;

[0020] S2.3: Mix modified ammonium polyphosphate, phosphorus-containing diamine monomer, melamine, 37-40% formaldehyde solution and deionized water, wherein the mass ratio of modified ammonium polyphosphate, phosphorus-containing diamine monomer, melamine, formaldehyde solution and deionized water is (0.1-0.4):(0.1-1):(1-2):(1.5-2.5):(1-6) to obtain a mixed solution, and then add triethanolamine until the pH value of the mixed solution reaches 8-8.5, and stir the reaction at 60-80°C for 1-2 hours to obtain a phosphorus-containing wall layer material.

[0021] Furthermore, the phosphorus-containing diamine monomer is at least one of a phosphorus-containing diamine monomer DAPPO, a phosphorus-containing diamine monomer PCDA, a phosphorus-containing diamine monomer BADPO, and bis[4-(3-aminophenoxy)phenyl]phenylphosphine oxide;

[0022] The structural formula of the phosphorus-containing diamine monomer DAPPO is shown below:

[0023]

[0024] The structural formula of phosphorus-containing diamine monomer PCDA is shown below:

[0025]

[0026] The structural formula of phosphorus-containing diamine monomer BADPO is shown below:

[0027]

[0028] The structural formula of bis[4-(3-aminophenoxy)phenyl]phenylphosphine oxide is shown below:

[0029]

[0030] Furthermore, step S3: preparing self-flame retardant phosphorus-containing phase change energy storage material microcapsules, specifically comprising the following steps:

[0031] S3.1: Mix deionized water, the composite phase change energy storage material, and the emulsifier, and stir at 60-70°C and 800-1500 rpm for 2-5 hours to obtain an oil-in-water emulsion;

[0032] S3.2: The phosphorus-containing wall layer material is uniformly added dropwise to the oil-in-water emulsion, and the reaction is carried out at 60-70°C for 2-4 hours. Subsequently, after reduced pressure filtration, filter residue collection, washing and vacuum drying, self-flame retardant phosphorus-containing phase change energy storage material microcapsules are obtained.

[0033] Furthermore, the mixing mass ratio of deionized water, composite phase change energy storage material and emulsifier is (2-10): (1-3): (0.01-0.08).

[0034] Furthermore, the mixing mass ratio of the phosphorus-containing wall layer material to the oil-in-water emulsion is (0.5-1):(1-6).

[0035] Furthermore, the emulsifier is at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, Span-20, Span-40, Span-60, Span-80, Tween-20, Tween-40, Tween-60, Tween-80 or TritonX-100.

[0036] A self-flame retardant phosphorus-containing phase change energy storage material microcapsule is prepared by the above-mentioned preparation process of the self-flame retardant phosphorus-containing phase change energy storage material microcapsule.

[0037] The present invention has the following advantages:

[0038] 1. In the present invention, paraffin wax is modified using hydroxylated magnesium oxide-boron nitride powder. The hydroxyl functional groups on the surface of the hydroxylated composite powder can increase the interaction between the hydroxylated magnesium oxide-boron nitride powder and the paraffin molecules, promoting the uniform distribution of the hydroxylated magnesium oxide-boron nitride powder in the paraffin wax. Furthermore, under the synergistic effect of nano-magnesium oxide and nano-boron nitride, the nano-magnesium oxide and nano-boron nitride loaded on the surface of the boron nitride can form an effective heat conduction network in the paraffin matrix, increasing the diffusion rate of thermal energy and accelerating the absorption and release of heat, thereby improving the thermal conductivity of the composite phase change energy storage material. In addition, the high thermal stability of boron nitride and magnesium oxide can provide flame retardant protection for the composite phase change energy storage material, slowing down the combustion process.

[0039] 2. In the present invention, ammonium polyphosphate is grafted with melamine to modify the surface of the ammonium polyphosphate. The obtained modified ammonium polyphosphate can effectively improve its dispersibility in the mixed liquid, thereby promoting the modified ammonium polyphosphate with melamine grafted on the surface to be more uniformly and effectively dispersed in the phosphorus-containing wall layer material, which helps to improve the flame retardant properties of the wall material of the self-flame retardant phosphorus-containing phase change energy storage material microcapsule.

[0040] 3. In the present invention, modified ammonium polyphosphate and phosphorus-containing diamine monomer, two inorganic phosphorus-containing compounds and organic phosphorus-containing compounds, are added together to form a phosphorus-containing wall material with self-flame retardant properties. The obtained phosphorus-containing wall material is used as the wall material of self-flame retardant phosphorus-containing phase change energy storage material microcapsules. Microencapsulation and coating of the composite phase change energy storage material can effectively prevent leakage of the composite phase change energy storage material and protect the composite phase change energy storage material from leakage. In addition, the microencapsulated self-flame retardant phosphorus-containing phase change energy storage material microcapsules have an extremely high specific surface area, which can effectively increase the thermal energy storage of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a flow chart of the preparation process of self-flame retardant phosphorus-containing phase change energy storage material microcapsules in an embodiment of the present invention.

[0042] Figure 2 This is a graph showing the test results of the physical and chemical properties of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules prepared in the examples and comparative examples of the present invention. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Example 1

[0045] A preparation process of self-flame retardant phosphorus-containing phase change energy storage material microcapsules, such as Figure 1 As shown, the specific steps include:

[0046] S1: Preparation of composite phase change energy storage materials,

[0047] S1.1: Immerse nano-boron nitride in a 30% magnesium nitrate solution with a solid-liquid mass ratio of 3:50. Ultrasonic dispersion is performed for 15 minutes, followed by immersion for 3 hours. The impregnated liquid is added to a rotary evaporator and evaporated and concentrated at 75°C for 20 minutes. Then, the liquid is dried at 120°C for 8 hours. After drying, the powder is ground and calcined at 400°C under a nitrogen atmosphere for 3 hours to obtain magnesium oxide-boron nitride powder.

[0048] S1.2: Add magnesium oxide-boron nitride composite powder to a 20% sodium hydroxide solution (solid-to-liquid ratio of magnesium oxide-boron nitride composite powder to 20% sodium hydroxide) at a solid-to-liquid ratio of 1:20. In an oil bath at 120°C, reflux under magnetic stirring for 18 hours. Cool, filter, and dry to obtain hydroxylated magnesium oxide-boron nitride powder.

[0049] S1.3: Add hydroxylated magnesium oxide-boron nitride powder to molten paraffin wax, wherein the amount of hydroxylated magnesium oxide-boron nitride powder added is 8% by weight of the paraffin wax, and stir magnetically at 65°C for 60 min at a speed of 600 rpm to obtain modified paraffin wax;

[0050] S1.4: Modified paraffin wax and silicate were mixed in a mass ratio of 2:1, magnetically stirred at 65°C for 90 minutes, and then ultrasonically shaken for 40 minutes to obtain a phase change material mixture;

[0051] S1.5: Transfer the phase change material mixture to a vacuum pressure sealed glass reactor, reduce the vacuum to 0.01 MPa and maintain the vacuum for 6 h to obtain a composite phase change energy storage material;

[0052] S2: Preparation of phosphorus-containing wall layer materials,

[0053] S2.1: Activate the ammonium polyphosphate by heating it to 220° C. for 3 hours, and then prepare the activated ammonium polyphosphate into a 1% by mass ammonium polyphosphate dispersed aqueous solution;

[0054] S2.2: Add melamine to the dispersed aqueous solution of ammonium polyphosphate, wherein the amount of melamine is 6% by mass of the activated ammonium polyphosphate, and react at 240° C. for 3 h to obtain modified ammonium polyphosphate;

[0055] S2.3: Modified ammonium polyphosphate, phosphorus-containing diamine monomer DAPPO, melamine, 40% formaldehyde solution, and deionized water are mixed in a mass ratio of 0.4:0.5:2:2:5 to obtain a mixed solution. Subsequently, triethanolamine is added until the pH value of the mixed solution reaches 8.5. The mixture is stirred and reacted at 80°C for 2 hours to obtain a phosphorus-containing wall layer material.

[0056] S3: Preparation of self-flame retardant phosphorus-containing phase change energy storage material microcapsules,

[0057] S3.1: Mix deionized water, sodium lauryl sulfate, and a composite phase change energy storage material in a mass ratio of 8:3:0.06, and stir at 70°C and 1500 rpm for 5 h to obtain an oil-in-water emulsion;

[0058] S3.2: The phosphorus-containing wall layer material is uniformly added dropwise to the oil-in-water emulsion, with a mass ratio of the phosphorus-containing wall layer material to the oil-in-water emulsion being 1:5. The reaction is carried out at 70°C for 4 hours. Subsequently, after reduced pressure filtration, filter residue collection, washing and vacuum drying, self-flame retardant phosphorus-containing phase change energy storage material microcapsules are obtained.

[0059] Example 2

[0060] A preparation process of self-flame retardant phosphorus-containing phase change energy storage material microcapsules, such as Figure 1 As shown, the specific steps include:

[0061] S1: Preparation of composite phase change energy storage materials,

[0062] S1.1: Immerse nano-boron nitride in a 30% magnesium nitrate solution with a solid-liquid mass ratio of 3:50. Ultrasonic dispersion is performed for 10 minutes, followed by immersion for 1 hour. The impregnated liquid is added to a rotary evaporator and evaporated and concentrated at 60°C for 10 minutes. Then, the liquid is dried at 100°C for 4 hours. After drying, the powder is ground and calcined at 380°C under a nitrogen atmosphere for 4 hours to obtain magnesium oxide-boron nitride powder.

[0063] S1.2: Add magnesium oxide-boron nitride composite powder to a 20% sodium hydroxide solution at a solid-liquid mass ratio of 1:20. In an oil bath at 100°C, reflux under magnetic stirring for 15 hours. Cool, filter, and dry to obtain hydroxylated magnesium oxide-boron nitride powder.

[0064] S1.3: Add hydroxylated magnesium oxide-boron nitride powder to molten paraffin wax, wherein the amount of hydroxylated magnesium oxide-boron nitride powder added is 8% by weight of the paraffin wax, and stir magnetically at 60°C for 40 min at a speed of 500 rpm to obtain modified paraffin wax;

[0065] S1.4: Modified paraffin wax and silicate were mixed in a mass ratio of 2:1, magnetically stirred at 60°C for 60 minutes, and then ultrasonically shaken for 20 minutes to obtain a phase change material mixture;

[0066] S1.5: Transfer the phase change material mixture to a vacuum pressure-sealed glass reactor, reduce the vacuum to 0.01 MPa, and maintain the vacuum for 4 h to obtain a composite phase change energy storage material;

[0067] S2: Preparation of phosphorus-containing wall layer materials,

[0068] S2.1: Activate the ammonium polyphosphate by heating it to 280° C. for 1 hour, and then prepare the activated ammonium polyphosphate into a 1% by mass ammonium polyphosphate dispersed aqueous solution;

[0069] S2.2: Add melamine to the dispersed aqueous solution of ammonium polyphosphate, wherein the amount of melamine is 6% by mass of the activated ammonium polyphosphate, and react at 200° C. for 1 h to obtain modified ammonium polyphosphate;

[0070] S2.3: Mixing modified ammonium polyphosphate, phosphorus-containing diamine monomer DAPPO, melamine, 40% formaldehyde solution, and deionized water in a mass ratio of 0.4:0.5:2:2:5 to obtain a mixed solution, then adding triethanolamine until the pH value of the mixed solution reaches 8.5, and stirring the mixture at 60°C for 1 hour to obtain a phosphorus-containing wall layer material;

[0071] S3: Preparation of self-flame retardant phosphorus-containing phase change energy storage material microcapsules,

[0072] S3.1: Deionized water, sodium lauryl sulfate, and a composite phase change energy storage material were mixed in a mass ratio of 8:3:0.06, and stirred at 65°C and 800 rpm for 2 h to obtain an oil-in-water emulsion.

[0073] S3.2: The phosphorus-containing wall layer material is uniformly added dropwise to the oil-in-water emulsion, the mass ratio of the phosphorus-containing wall layer material to the oil-in-water emulsion is 1:5, and the reaction is carried out at 60°C for 2 hours. Subsequently, after reduced pressure filtration, filter residue collection, washing and vacuum drying, self-flame retardant phosphorus-containing phase change energy storage material microcapsules are obtained.

[0074] Example 3

[0075] A preparation process of self-flame retardant phosphorus-containing phase change energy storage material microcapsules, such as Figure 1 As shown, the specific steps include:

[0076] S1: Preparation of composite phase change energy storage materials,

[0077] S1.1: Immerse nano-boron nitride in a 30% magnesium nitrate solution with a solid-liquid mass ratio of 1:30, ultrasonically disperse for 15 minutes, and then immerse for 3 hours. The impregnated liquid is added to a rotary evaporator and evaporated and concentrated at 75°C for 20 minutes. Then, it is dried at 120°C for 8 hours. After drying, it is ground and calcined at 400°C under a nitrogen atmosphere for 3 hours to obtain magnesium oxide-boron nitride powder;

[0078] S1.2: Add magnesium oxide-boron nitride composite powder to a 20% sodium hydroxide solution (solid-to-liquid ratio of magnesium oxide-boron nitride composite powder to 20% sodium hydroxide) at a solid-to-liquid ratio of 1:50. In an oil bath at 120°C, reflux under magnetic stirring for 18 hours. Cool, filter, and dry to obtain hydroxylated magnesium oxide-boron nitride powder.

[0079] S1.3: Add hydroxylated magnesium oxide-boron nitride powder to molten paraffin wax, wherein the amount of hydroxylated magnesium oxide-boron nitride powder added is 3% of the mass of the paraffin wax, and stir magnetically at 65°C for 60 minutes at a speed of 600 rpm to obtain modified paraffin wax;

[0080] S1.4: Modified paraffin wax and silicate were mixed in a mass ratio of 1:1, magnetically stirred at 65°C for 90 minutes, and then ultrasonically shaken for 40 minutes to obtain a phase change material mixture;

[0081] S1.5: Transfer the phase change material mixture to a vacuum pressure sealed glass reactor, reduce the vacuum to 0.01 MPa and maintain the vacuum for 6 h to obtain a composite phase change energy storage material;

[0082] S2: Preparation of phosphorus-containing wall layer materials,

[0083] S2.1: Activate the ammonium polyphosphate by heating it to 220° C. for 3 hours, and then prepare the activated ammonium polyphosphate into a 3% by mass ammonium polyphosphate dispersed aqueous solution;

[0084] S2.2: Add melamine to the dispersed aqueous solution of ammonium polyphosphate, wherein the amount of melamine is 6% by mass of the activated ammonium polyphosphate, and react at 240° C. for 3 h to obtain modified ammonium polyphosphate;

[0085] S2.3: Modified ammonium polyphosphate, phosphorus-containing diamine monomer DAPPO, melamine, 40% formaldehyde solution, and deionized water are mixed in a mass ratio of 0.1:0.1:1:1:3 to obtain a mixed solution. Subsequently, triethanolamine is added until the pH value of the mixed solution reaches 8.5. The mixture is stirred and reacted at 80°C for 2 hours to obtain a phosphorus-containing wall layer material.

[0086] S3: Preparation of self-flame retardant phosphorus-containing phase change energy storage material microcapsules,

[0087] S3.1: Mix deionized water, sodium lauryl sulfate, and a composite phase change energy storage material in a mass ratio of 5:1:0.01, and stir at 70°C and 1500 rpm for 5 h to obtain an oil-in-water emulsion;

[0088] S3.2: The phosphorus-containing wall layer material is uniformly added dropwise to the oil-in-water emulsion, with a mass ratio of the phosphorus-containing wall layer material to the oil-in-water emulsion being 1:3. The reaction is carried out at 70°C for 4 hours. Subsequently, after reduced pressure filtration, the filter residue is collected, washed and vacuum dried to obtain self-flame retardant phosphorus-containing phase change energy storage material microcapsules.

[0089] Comparative Example 1

[0090] Compared with Example 1, the difference of Comparative Example 1 is that step S1.2 is removed, and the hydroxylated magnesium oxide-boron nitride powder in step S1.3 is replaced by the magnesium oxide-boron nitride powder obtained in step S1.1, and the paraffin is modified using the magnesium oxide-boron nitride powder to obtain modified paraffin. The other steps remain unchanged to prepare self-flame retardant phosphorus-containing phase change energy storage material microcapsules, which is recorded as Comparative Example 1.

[0091] Comparative Example 2

[0092] Compared with Example 1, the difference of Comparative Example 2 is that step S1.1 is removed, the magnesium oxide-boron nitride composite powder in step S1.2 is replaced by nano-boron nitride to prepare hydroxylated boron nitride powder, the hydroxylated magnesium oxide-boron nitride powder in step S1.3 is replaced by hydroxylated boron nitride powder, and the paraffin is modified using the hydroxylated boron nitride powder to obtain modified paraffin. The other steps remain unchanged to prepare self-flame retardant phosphorus-containing phase change energy storage material microcapsules, which is recorded as Comparative Example 2.

[0093] Comparative Example 3

[0094] Compared with Example 1, the difference of Comparative Example 3 is that step S1.1 is removed, the magnesium oxide-boron nitride composite powder in step S1.2 is replaced by nano-magnesium oxide to prepare hydroxylated magnesium oxide powder, the hydroxylated magnesium oxide-boron nitride powder in step S1.3 is replaced by hydroxylated magnesium oxide powder, and the paraffin is modified using the hydroxylated magnesium oxide powder to obtain modified paraffin. The other steps remain unchanged to prepare self-flame retardant phosphorus-containing phase change energy storage material microcapsules, which is recorded as Comparative Example 3.

[0095] Comparative Example 4

[0096] Compared with Example 1, the difference of Comparative Example 4 is that the modified ammonium polyphosphate in step S2.3 is removed, and the phosphorus-containing diamine monomer DAPPO, melamine, a formaldehyde solution with a mass fraction of 40% and deionized water are stirred and mixed in a mass ratio of 0.5:2:2:5 to obtain a mixed solution. Subsequently, triethanolamine is added until the pH value of the mixed solution reaches 8.5, and the reaction is stirred at 80°C for 2h to obtain a phosphorus-containing wall layer material. The other steps remain unchanged, and self-flame retardant phosphorus-containing phase change energy storage material microcapsules are prepared, which is recorded as Comparative Example 4.

[0097] Comparative Example 5

[0098] Compared with Example 1, the difference of Comparative Example 5 is that the phosphorus-containing diamine monomer DAPPO in step S2.3 is removed, and the modified ammonium polyphosphate, melamine, 40% formaldehyde solution and deionized water are mixed in a mass ratio of 0.4:2:2:5 and stirred to obtain a mixed solution. Subsequently, triethanolamine is added until the pH value of the mixed solution reaches 8.5, and the reaction is stirred at 80°C for 2h to obtain a phosphorus-containing wall layer material. The other steps remain unchanged, and self-flame retardant phosphorus-containing phase change energy storage material microcapsules are prepared, which is recorded as Comparative Example 5.

[0099] The physicochemical properties of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules in Examples 1-3 and Comparative Examples 1-5 were tested as follows:

[0100] The phase change enthalpy values ​​of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules in the melting and solidification processes of Examples 1-3 and Comparative Examples 1-5 were tested using a differential scanning calorimeter. The test conditions were as follows: under a nitrogen atmosphere, the temperature test range was -20°C to 120°C, the heating rate was 10°C / min, and the sample weight was about 5 mg; the thermal conductivity coefficient of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules in Examples 1-3 and Comparative Examples 1-5 was measured using a thermal conductivity coefficient tester; the limiting oxygen index of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules in Examples 1-3 and Comparative Examples 1-5 was measured using an oxygen index tester. The test results are as follows: Figure 2 shown.

[0101] like Figure 2 It can be seen that the self-flame-retardant phosphorus-containing phase change energy storage material microcapsules in Examples 1-3, whether in terms of melting enthalpy, solidification enthalpy, thermal conductivity, or limiting oxygen index, all have test results superior to those of Comparative Examples 1-5. This indicates that the composite phase change energy storage material prepared using modified paraffin wax, and the addition of modified ammonium polyphosphate and phosphorus-containing diamine monomer to the phosphorus-containing wall layer material, can improve the flame retardant properties of the prepared self-flame-retardant phosphorus-containing phase change energy storage material microcapsules. Compared to the modification of paraffin wax using magnesium oxide-boron nitride powder, hydroxylated boron nitride powder, and hydroxylated magnesium oxide powder, the composite phase change energy storage material prepared using paraffin wax modified with hydroxylated magnesium oxide-boron nitride powder, and then processed to form self-flame-retardant phosphorus-containing phase change energy storage material microcapsules, the resulting self-flame-retardant phosphorus-containing phase change energy storage material microcapsules have better thermal conductivity and flame retardant properties. In addition, Examples 1-3 use phosphorus-containing wall materials added with modified ammonium polyphosphate and phosphorus-containing diamine monomer DAPPO to prepare the wall materials of self-flame retardant phosphorus-containing phase change energy storage material microcapsules, and their melting enthalpy and solidification enthalpy values ​​are both maintained above 190 J / g, indicating that the addition of two inorganic phosphorus-containing compounds and organic phosphorus-containing compounds, modified ammonium polyphosphate and phosphorus-containing diamine monomers, in the wall materials of flame-retardant phosphorus-containing phase change energy storage material microcapsules can enable the modified ammonium polyphosphate and phosphorus-containing diamine monomers to cooperate with each other, increase the thermal energy storage of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules, and enable the wall materials of the flame-retardant phosphorus-containing phase change energy storage material microcapsules to have good thermal energy storage capacity.

[0102] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A self-flame retardant phosphorus-containing phase change energy storage material microcapsule, characterized in that: The steps include: S1: Preparation of composite phase change energy storage material, immersing nano-boron nitride in magnesium nitrate solution, and obtaining magnesium oxide-boron nitride powder through impregnation, evaporation concentration, drying, grinding and calcination. The obtained magnesium oxide-boron nitride powder is subjected to hydroxylation modification treatment, and the obtained hydroxylated magnesium oxide-boron nitride powder is mixed with paraffin to obtain modified paraffin. The modified paraffin is mixed with silicate to obtain composite phase change energy storage material; S2: preparing a phosphorus-containing wall layer material, after heating and activating ammonium polyphosphate, grafting melamine on the surface of the ammonium polyphosphate to obtain modified ammonium polyphosphate, mixing the modified ammonium polyphosphate, a phosphorus-containing diamine monomer, melamine, a formaldehyde solution and deionized water for reaction, wherein the mass ratio of the modified ammonium polyphosphate, the phosphorus-containing diamine monomer, melamine, the formaldehyde solution and the deionized water is (0.1-0.4):(0.1-1):(1-2):(1.5-2.5):(1-6) to obtain a phosphorus-containing wall layer material; S3: Preparation of self-flame retardant phosphorus-containing phase change energy storage material microcapsules, deionized water, an emulsifier and a composite phase change energy storage material are mixed and stirred to obtain an oil-in-water emulsion, the phosphorus-containing wall layer material is uniformly added dropwise to the oil-in-water emulsion, heated for reaction, and then filtered under reduced pressure, the filter residue is collected, washed and dried to obtain self-flame retardant phosphorus-containing phase change energy storage material microcapsules; The preparation method of hydroxylated magnesium oxide-boron nitride powder is as follows: The magnesium oxide-boron nitride composite powder is added to a sodium hydroxide solution having a mass fraction of 20%, wherein the solid-liquid mass ratio of the magnesium oxide-boron nitride composite powder to the sodium hydroxide having a mass fraction of 20% is (1-5):(50-100), and the mixture is refluxed under magnetic stirring under condensation for 15-18 hours in an oil bath at 100-120°C, and then cooled, filtered and dried to obtain hydroxylated magnesium oxide-boron nitride powder. Step S2: Preparation of phosphorus-containing wall layer material, specifically comprising the following steps: S2.1: Activate the ammonium polyphosphate by heating it to 200-280°C for 1-3 hours, and then prepare the activated ammonium polyphosphate into a dispersed aqueous solution having a mass fraction of 1-3% ammonium polyphosphate; S2.2: Add melamine to the dispersed aqueous solution of ammonium polyphosphate, with the amount of melamine being 3-6% of the mass of the activated ammonium polyphosphate, and react at 200-240° C. for 1-3 hours to obtain modified ammonium polyphosphate.

2. The method for preparing the self-flame retardant phosphorus-containing phase change energy storage material microcapsules according to claim 1, characterized in that: Step S1: Preparation of composite phase change energy storage material, specifically including the following steps: S1.1: Immerse nano-boron nitride in a 30% by mass magnesium nitrate solution, wherein the solid-liquid mass ratio of nano-boron nitride to the 30% by mass magnesium nitrate solution is (1-6):(30-100), ultrasonically disperse for 10-15 minutes, and then immerse for 1-3 hours. The impregnated liquid is added to a rotary evaporator, evaporated and concentrated at 50-75°C for 10-20 minutes, and then dried at 100-120°C for 4-8 hours. After drying, the powder is ground and calcined to obtain magnesium oxide-boron nitride powder. S1.2: Add hydroxylated magnesium oxide-boron nitride powder to molten paraffin wax, wherein the amount of hydroxylated magnesium oxide-boron nitride powder added is 3-10% by weight of the paraffin wax, and stir magnetically at 60-65°C for 40-60 minutes at a speed of 500-600 rpm to obtain modified paraffin wax; S1.3: Modified paraffin wax and silicate are mixed in a mass ratio of (1-4):(1-2), magnetically stirred at 60-65°C for 60-90 minutes, and then ultrasonically shaken for 20-40 minutes to obtain a phase change material mixture; S1.4: Transfer the phase change material mixture to a vacuum pressure sealed glass reactor, reduce the vacuum to 0.01 MPa and maintain the vacuum for 4 to 6 hours to obtain a composite phase change energy storage material.

3. The preparation process of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules according to claim 2, characterized in that: In step S1.1, the calcination operation is carried out under a nitrogen atmosphere at a calcination temperature of 380-410° C. for 3-4 hours.

4. The preparation process of the self-flame retardant phosphorus-containing phase change energy storage material microcapsules according to claim 3, characterized in that: Step S2: Preparation of phosphorus-containing wall layer material, specifically comprising the following steps: Modified ammonium polyphosphate, phosphorus-containing diamine monomer, melamine, 37-40% formaldehyde solution and deionized water are mixed to obtain a mixed solution. Subsequently, triethanolamine is added until the pH value of the mixed solution reaches 8-8.5, and the mixture is stirred and reacted at 60-80° C. for 1-2 hours to obtain a phosphorus-containing wall layer material.

5. The process for preparing the self-flame retardant phosphorus-containing phase change energy storage material microcapsules according to claim 4, characterized in that: The phosphorus-containing diamine monomer is at least one of a phosphorus-containing diamine monomer DAPPO, a phosphorus-containing diamine monomer PCDA, a phosphorus-containing diamine monomer BADPO, and bis[4-(3-aminophenoxy)phenyl]phenylphosphine oxide.

6. The process for preparing the self-flame retardant phosphorus-containing phase change energy storage material microcapsules according to claim 4, characterized in that: Step S3: Preparation of self-flame retardant phosphorus-containing phase change energy storage material microcapsules, specifically comprising the following steps: S3.1: Mix deionized water, the composite phase change energy storage material, and the emulsifier, and stir at 60-70°C and 800-1500 rpm for 2-5 hours to obtain an oil-in-water emulsion; S3.2: The phosphorus-containing wall layer material is uniformly added dropwise to the oil-in-water emulsion, and the reaction is carried out at 60-70°C for 2-4 hours. Subsequently, after reduced pressure filtration, filter residue collection, washing and vacuum drying, self-flame retardant phosphorus-containing phase change energy storage material microcapsules are obtained.

7. The process for preparing the self-flame retardant phosphorus-containing phase change energy storage material microcapsules according to claim 6, characterized in that: The mixing mass ratio of deionized water, composite phase change energy storage material and emulsifier is (2-10): (1-3): (0.01-0.08).

8. The process for preparing the self-flame retardant phosphorus-containing phase change energy storage material microcapsules according to claim 7, characterized in that: The mixing mass ratio of the phosphorus-containing wall layer material to the oil-in-water emulsion is (0.5-1): (1-6).

9. The process for preparing the self-flame retardant phosphorus-containing phase change energy storage material microcapsules according to claim 8, characterized in that: The emulsifier is at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, Span-20, Span-40, Span-60, Span-80, Tween-20, Tween-40, Tween-60, Tween-80 or TritonX-100.

10. A self-flame retardant phosphorus-containing phase change energy storage material microcapsule, characterized in that: The microcapsule is prepared by the preparation process of a self-flame retardant phosphorus-containing phase change energy storage material microcapsule according to any one of claims 1 to 9.

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