Lightweight building heat insulation board and preparation method thereof

Abstract

The invention provides a light building heat insulation board and a preparation method thereof, and belongs to the technical field of building energy-saving materials. The composite phase-change material is dispersed in the polyurethane matrix, and comprises silicon dioxide aerogel, silicon dioxide aerogel, silicon dioxide sol, silicon dioxide sol, silicon dioxide sol, silicon dioxide sol and silicon dioxide sol; the disodium hydrogen phosphate dodecahydrate is loaded in the silicon dioxide aerogel. According to the invention, the light and efficient building heat insulation board is prepared by synergistically integrating the efficient heat insulation and stable packaging of the silicon dioxide aerogel, the phase change heat storage function of the disodium hydrogen phosphate dodecahydrate and the good mechanical and processing properties of the polyurethane matrix.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building energy-saving materials, and particularly relates to a light building thermal insulation board and a preparation method thereof. BACKGROUND

[0002] With the increasing requirement of building energy saving, thermal insulation materials play an increasingly important role in green building and low-carbon construction. Traditional building insulation materials, such as polystyrene foam, extruded polystyrene board and polyurethane hard foam, have certain thermal insulation performance, but their heat capacity is low, the temperature adjusting capacity is limited, and they are difficult to cope with the use environment with large diurnal or seasonal temperature difference, which easily leads to significant indoor temperature fluctuation and increases the energy consumption of heating, ventilation and air conditioning system.

[0003] To improve the thermal energy storage capacity of the insulation material, phase change materials are introduced into the field of building insulation. Among them, hydrated salt phase change materials, such as dodecahydrate disodium hydrogen phosphate, show good application prospects due to their high phase change enthalpy, suitable phase change temperature and low cost. However, such materials have problems such as easy leakage, phase separation and poor cycle stability in actual application, which seriously restricts their promotion in actual engineering.

[0004] To overcome the above-mentioned defects, existing research usually encapsulates phase change materials with porous carriers, such as expanded perlite, diatomite and mesoporous silicon oxide. However, when conventional porous materials are compounded with polymer matrix (such as polyurethane), the mechanical properties of the materials are often reduced due to poor interfacial compatibility and uneven dispersion, which even affects the overall effect of thermal insulation. In addition, in the existing composite insulation board with polyurethane as the matrix, the introduction of phase change materials is usually by physical blending, which easily leads to leakage and aggregation of effective components, reducing the service life and thermal performance stability of the material. SUMMARY

[0005] In view of the above situation, to overcome the defects of the prior art, the purpose of the present application is to provide a light building thermal insulation board and a preparation method thereof, to at least partially solve the problems raised in the background art.

[0006] The technical solutions adopted by the present application are as follows: The present application provides a light building thermal insulation board, comprising: a polyurethane matrix; and a composite phase change material dispersed in the polyurethane matrix, the composite phase change material comprising: silica aerogel and dodecahydrate disodium hydrogen phosphate, the dodecahydrate disodium hydrogen phosphate being loaded in the silica aerogel.

[0007] In some embodiments of the present application, the mass ratio of the composite phase change material to the polyurethane matrix is 1:10 to 5:10.

[0008] In some embodiments of the present application, the mass ratio of the silica aerogel to the disodium hydrogen phosphate dodecahydrate in the composite phase change material is 5:1 to 3:1.

[0009] In some embodiments of the present application, the silica aerogel is prepared from a precursor composed of diphenylmethane bismaleimide and 3-mercaptopropyl triethoxysilane.

[0010] In some embodiments of the present application, the polyurethane matrix is formed from a reaction system comprising: a polyether polyol; a polyphenyl polymethylene polyisocyanate; a foaming agent; a crosslinking agent; and a foam stabilizer.

[0011] In some embodiments of the present application, the polyether polyol is polyethylene glycol, the foaming agent is cyclopentane, the crosslinking agent is diethylene glycol, and the foam stabilizer is dimethyl silicone oil.

[0012] A second aspect of the present application provides a method for preparing a light building thermal insulation board, comprising the following steps: adding a composite phase change material, a foaming agent, a crosslinking agent, and a foam stabilizer to a polyether polyol, stirring until mixed uniformly, then adding a polyphenyl polymethylene polyisocyanate, rapidly stirring to perform a foaming reaction, and then pouring the foamed mixture into a mold to solidify, thereby obtaining the light building thermal insulation board.

[0013] In some embodiments of the present application, the method for preparing the composite phase change material comprises the following steps: dissolving disodium hydrogen phosphate dodecahydrate in deionized water, heating to complete dissolution, and obtaining a solution; adding silica aerogel to the solution, stirring for 30-60 min, and then placing in a vacuum drying oven to perform vacuum drying, thereby obtaining the composite phase change material.

[0014] In some embodiments of the present application, the method for preparing the silica aerogel comprises the following steps: dissolving diphenylmethane bismaleimide and 3-mercaptopropyl triethoxysilane in tetrahydrofuran, adding a catalyst triethylamine, and stirring to react at room temperature for 10-12 h, thereby obtaining a precursor; dissolving the precursor in a mixed solvent of ethanol and tetrahydrofuran, adding deionized water and hydrochloric acid, stirring until uniform, and standing until gelation, thereby obtaining a gel; performing vacuum drying on the gel, and grinding through a 200-mesh sieve, thereby obtaining the silica aerogel.

[0015] In some embodiments of the present application, the molar ratio of the diphenylmethane bismaleimide to 3-mercaptopropyl triethoxysilane is 1:1.8 to 1:2.2.

[0016] The present application has the following beneficial effects: The present application solves the technical problems of single function of traditional thermal insulation materials, easy leakage of phase change materials, and poor compatibility of phase change materials with matrix, and exhibits important application value in the field of building energy saving by synergistic integration of high-efficiency thermal insulation and stable packaging of silica aerogel, phase change heat storage function of disodium hydrogen phosphate dodecahydrate, and good mechanical and processing properties of polyurethane matrix. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art. In addition, any method and material similar or equivalent to those described herein can be used in the present application. The preferred implementation methods and materials described herein are only used for demonstration, but cannot limit the content of the present application.

[0019] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The ranges and values should be construed to be approximations that allow for significant variation. For ranges, the endpoints are provided as a roughly correct indication of the range but are not to be construed as limiting to the range. For example, a range of 1 to 6 should be interpreted to include not only the precise ranges of 1-6 and 2-5, but also other ranges such as 1.5-4.8 and 2.2-4.4, etc. Similarly, whole ranges provided should be interpreted as not only the stated ranges but also to include major subdivisions within the stated ranges and also include individual points or values within the stated ranges. For example, a range of 1-10 should be interpreted to include not only the precise ranges of 1-10, but also other ranges such as 2-9, 3-8, 4-7, etc., as well as individual points or values within the stated ranges, such as 2, 3, 4, 5, 6, 7, 8, 9, and 10, etc.

[0020] To solve the problems proposed in the background art, the first aspect of the embodiments of the present application proposes a light-weight building thermal insulation board, comprising: a polyurethane matrix; and a composite phase change material dispersed in the polyurethane matrix, the composite phase change material comprising: silica aerogel and disodium hydrogen phosphate dodecahydrate, the disodium hydrogen phosphate dodecahydrate being loaded in the silica aerogel.

[0021] The light building thermal insulation board provided by the embodiment of the present application has significant technical progress in thermal insulation performance, thermal regulation capacity, stability and comprehensive application performance through innovative composite design and function synergy of polyurethane matrix and composite phase change material. The core is to select disodium hydrogen phosphate dodecahydrate as the phase change energy storage material, and innovatively use silica aerogel as the carrier and stabilizer to successfully build a high-efficiency heat storage-thermal insulation integrated functional system. In the system, the silica aerogel greatly prolongs the heat conduction path and significantly improves the overall thermal insulation performance of the material due to its extremely low thermal conductivity and three-dimensional nano-porous structure; and the disodium hydrogen phosphate dodecahydrate absorbs and releases a large amount of latent heat through the solid-liquid phase change process, effectively stabilizes the environmental temperature fluctuation, and gives the board active thermal regulation capacity.

[0022] Meanwhile, the present application successfully solves the technical bottleneck of easy leakage and phase separation of inorganic hydrated salt phase change material through the carrier design and surface characteristics of silica aerogel. The abundant mesoporous structure and large specific surface area of fumed silica provide sufficient adsorption sites for disodium hydrogen phosphate dodecahydrate, which is stably confined in the pores thereof through capillary force, surface tension and hydrogen bond interaction, thereby ensuring the shape stability and functional reliability of the material during long-term use, and fundamentally overcoming the phase separation and performance degradation problems of traditional phase change materials and polymer matrix simple blending.

[0023] In addition, the thermal insulation board realizes the integration and enhancement of functions through the ingenious combination of composite phase change material and polyurethane matrix. The polyurethane matrix itself has good mechanical strength, adhesion and processability, providing a stable support frame and good construction adaptability for the composite material; and the composite phase change material uniformly dispersed therein cooperatively contributes efficient thermal insulation and heat storage functions. The light thermal insulation board is suitable for building external wall insulation, cold storage insulation and special occasions requiring constant temperature environment, and the board form is convenient for installation and does not affect the flexibility of building design. The cured board is light in quality, high in strength, and has excellent passive thermal insulation and active temperature regulation capacity.

[0024] In summary, the present application integrates the efficient thermal insulation and stable packaging of silica aerogel, the phase change heat storage function of disodium hydrogen phosphate dodecahydrate, and the good mechanical and processing properties of polyurethane matrix to prepare a light and efficient building thermal insulation board, which solves the technical problems of single function of traditional thermal insulation materials, easy leakage of phase change materials and poor compatibility with matrix, and has important application value in the field of building energy saving.

[0025] In some embodiments, the mass ratio of the composite phase change material to the polyurethane matrix is 1:10 to 5:10. If the content of the composite phase change material in the polyurethane matrix is too high, the continuity of the polyurethane matrix will be damaged, and the phenomena of cell collapse and expansion will occur, which will significantly reduce the mechanical strength of the material. If the content of the composite phase change material in the polyurethane matrix is too low, the latent heat storage capacity provided by the composite phase change material will be insufficient, and the temperature fluctuation cannot be effectively smoothed. Therefore, by setting the mass ratio of the composite phase change material to the polyurethane matrix to 1:10 to 5:10, the insulation board can have excellent thermal insulation performance and mechanical properties.

[0026] In some embodiments, in the composite phase change material, the mass ratio of the silica aerogel to the disodium hydrogen phosphate dodecahydrate is 5:1 to 3:1. By setting the mass ratio of the silica aerogel to the disodium hydrogen phosphate dodecahydrate to 5:1 to 3:1, the silica aerogel can form a complete three-dimensional network structure to effectively wrap the disodium hydrogen phosphate dodecahydrate crystals, and at the same time, the phase change composite material can still maintain a relatively high phase change enthalpy value and has better thermal stability.

[0027] In some embodiments, the silica aerogel is prepared from a precursor composed of diphenylmethane bismaleimide and 3-mercaptopropyl triethoxysilane. The mercapto group on the 3-mercaptopropyl triethoxysilane can react with the maleimide group on the diphenylmethane bismaleimide, thereby forming a precursor containing organic segments and reactive siloxane groups. This structure greatly improves the compatibility of the aerogel with the polyurethane, reduces the phase separation phenomenon, and improves the dispersion performance of the aerogel in the polymer matrix.

[0028] In some embodiments, the polyurethane matrix is formed from a reaction system comprising: a polyether polyol; a polyphenyl polymethylene polyisocyanate; a foaming agent; a crosslinking agent; and a foam stabilizer.

[0029] In some embodiments, the polyether polyol is polyethylene glycol, the foaming agent is cyclopentane, the crosslinking agent is diethylene glycol, and the foam stabilizer is dimethyl silicone oil. The foaming agent cyclopentane is a low-boiling liquid, and the heat released during the reaction causes it to vaporize, generating bubbles, which is one of the main driving forces for foam expansion. The foam stabilizer dimethyl silicone oil can reduce the surface tension of the system, help the nucleation and stable growth of bubbles, prevent cell merging and collapse, and form a uniform and fine cell structure. The diethylene glycol contains two -OH groups, which can react with -NCO to connect the molecular chains, increase the crosslinking density and rigidity of the foam, and thus enhance the mechanical strength.

[0030] The second aspect of the present application provides a preparation method of a lightweight building thermal insulation board, comprising the following steps: adding a composite phase change material, a foaming agent, a crosslinking agent and a foam stabilizer into polyether polyol, stirring until mixed uniformly, then adding a polyphenyl polymethylene polyisocyanate, rapidly stirring to perform a foaming reaction, then pouring the foamed mixture into a mold to solidify, and obtaining the lightweight building thermal insulation board. A one-step method is adopted, that is, all raw materials (polyol, catalyst, foaming agent, foam stabilizer, etc.) are pre-mixed as component A, then component B (isocyanate) is rapidly mixed and poured into a mold, and the reaction and foaming are simultaneously performed. This method is simple in operation and high in efficiency.

[0031] In some embodiments, the preparation method of the composite phase change material comprises the following steps: dissolving disodium hydrogen phosphate dodecahydrate in deionized water, heating to completely dissolve, and obtaining a solution; adding silica aerogel into the solution, stirring for 30-60 min, and placing in a vacuum drying box after stirring to perform vacuum drying, and obtaining the composite phase change material. The disodium hydrogen phosphate dodecahydrate in the solution naturally penetrates into the porous network of the silica aerogel by capillary action, and the disodium hydrogen phosphate dodecahydrate crystallizes in the pores of the silica aerogel after cooling, thereby obtaining the composite phase change material.

[0032] In some embodiments, the preparation method of the silica aerogel comprises the following steps: dissolving diphenylmethane bismaleimide and 3-mercaptopropyl triethoxysilane into tetrahydrofuran, adding a catalyst triethylamine, stirring at room temperature for 10-12 h to obtain a precursor; dissolving the precursor in a mixed solvent of ethanol and tetrahydrofuran, adding deionized water and hydrochloric acid, stirring uniformly, and standing until gelation to obtain a gel; performing vacuum drying on the gel, and grinding through a 200-mesh sieve to obtain the silica aerogel.

[0033] In the tetrahydrofuran solvent, the maleimide groups of the diphenylmethane bismaleimide and the mercapto groups of the 3-mercaptopropyl triethoxysilane undergo a click chemistry reaction under the catalysis of triethylamine to generate an organically modified silane precursor. Subsequently, the ethoxyl groups in the 3-mercaptopropyl triethoxysilane are hydrolyzed into silicon hydroxyl groups under the catalysis of water and hydrochloric acid, and these silicon hydroxyl groups further condense to form an inorganic network skeleton of Si-O-Si, while the organic bridging structure provided by the diphenylmethane bismaleimide is integrated into the three-dimensional network. Finally, a gel with an organic-inorganic hybrid structure is formed through a sol-gel process.

[0034] In some embodiments, the molar ratio of the diphenylmethane bismaleimide to the 3-mercaptopropyl triethoxysilane is 1:1.8 to 1:2.2. By setting the molar ratio of the diphenylmethane bismaleimide to the 3-mercaptopropyl triethoxysilane to 1:1.8 to 1:2.2, a precursor with high crosslinking degree can be formed, and the mechanical strength of the aerogel is improved.

[0035] The application will be further described in the following with specific examples.

[0036] The experimental methods in the following examples are all conventional methods in the prior art, unless otherwise specified; the experimental materials used in the following examples are all purchased from commercial channels, unless otherwise specified.

[0037] Example 1 Diphenylmethane bismaleimide and 3-mercaptopropyl triethoxysilane were dissolved into tetrahydrofuran according to a molar ratio of 1:1.8, a catalyst triethylamine was added, and the reaction was stirred at room temperature for 10 h. After the reaction was completed, the remaining tetrahydrofuran and triethylamine were evaporated to obtain a precursor; The precursor was dissolved in a mixed solvent of ethanol and tetrahydrofuran, deionized water and hydrochloric acid were added, and stirred until uniform. After standing until gelation, a gel was obtained. The gel was vacuum dried and ground through a 200-mesh sieve to obtain a silica aerogel.

[0038] Sodium phosphate dibasic dodecahydrate was dissolved in deionized water and heated until completely dissolved to obtain a solution; The silica aerogel was added to the solution, and the mass ratio of the silica aerogel to sodium phosphate dibasic dodecahydrate was 5:1. After stirring for 30 min, the mixture was placed in a vacuum drying oven for vacuum drying to obtain a composite phase change material.

[0039] According to weight parts, 60 parts of polyether polyol were added with 10 parts of the composite phase change material, 0.5 parts of a foaming agent, 0.5 parts of a crosslinking agent, and 0.1 parts of a foam stabilizer, and stirred until uniform. Then, 40 parts of a polyphenyl polymethylene polyisocyanate was added, and the mixture was quickly stirred for foaming reaction. Then, the foamed mixture was poured into a mold for solidification to obtain a lightweight building thermal insulation board.

[0040] Example 2 Diphenylmethane bismaleimide and 3-mercaptopropyl triethoxysilane were dissolved into tetrahydrofuran according to a molar ratio of 1:2.2, a catalyst triethylamine was added, and the reaction was stirred at room temperature for 12 h. After the reaction was completed, the remaining tetrahydrofuran and triethylamine were evaporated to obtain a precursor; The precursor was dissolved in a mixed solvent of ethanol and tetrahydrofuran, deionized water and hydrochloric acid were added, and stirred until uniform. After standing until gelation, a gel was obtained. The gel was vacuum dried and ground through a 200-mesh sieve to obtain a silica aerogel.

[0041] Sodium phosphate dibasic dodecahydrate was dissolved in deionized water and heated until completely dissolved to obtain a solution; The silica aerogel is added into the solution, the mass ratio of the silica aerogel to the disodium hydrogen phosphate dodecahydrate is 3:1, stirring for 60 min, and then placed in a vacuum drying oven for vacuum drying to obtain the composite phase change material.

[0042] According to the weight parts, 60 parts of polyether polyol are added with 20 parts of the composite phase change material, 0.5 parts of the foaming agent, 0.5 parts of the crosslinking agent and 0.1 parts of the foam stabilizer, stirring until mixed uniformly, then 40 parts of the polyphenyl polymethylene polyisocyanate is added, and the foaming reaction is carried out by rapid stirring, and then the foamed mixture is poured into a mold for curing to obtain a lightweight building thermal insulation board.

[0043] Example 3: Diphenylmethane bismaleimide and 3-mercaptopropyl triethoxysilane are dissolved into tetrahydrofuran according to a molar ratio of 1:2, a catalyst triethylamine is added, and stirring is carried out at room temperature for 10 h, and then the remaining tetrahydrofuran and triethylamine are evaporated to obtain a precursor; The precursor is dissolved in a mixed solvent of ethanol and tetrahydrofuran, deionized water and hydrochloric acid are added, and stirring is carried out until uniform, and then the gel is obtained by standing until gelation. The gel is vacuum dried and ground through a 200-mesh sieve to obtain the silica aerogel.

[0044] The disodium hydrogen phosphate dodecahydrate is dissolved in deionized water, heated until completely dissolved to obtain a solution; The silica aerogel is added into the solution, the mass ratio of the silica aerogel to the disodium hydrogen phosphate dodecahydrate is 4:1, stirring for 60 min, and then placed in a vacuum drying oven for vacuum drying to obtain the composite phase change material.

[0045] According to the weight parts, 60 parts of polyether polyol are added with 30 parts of the composite phase change material, 0.5 parts of the foaming agent, 0.5 parts of the crosslinking agent and 0.1 parts of the foam stabilizer, stirring until mixed uniformly, then 40 parts of the polyphenyl polymethylene polyisocyanate is added, and the foaming reaction is carried out by rapid stirring, and then the foamed mixture is poured into a mold for curing to obtain a lightweight building thermal insulation board.

[0046] Example 4: The preparation method of the composite phase change material is consistent with that of Example 3, and the difference is that: According to the weight parts, 60 parts of polyether polyol are added with 40 parts of the composite phase change material, 0.5 parts of the foaming agent, 0.5 parts of the crosslinking agent and 0.1 parts of the foam stabilizer, stirring until mixed uniformly, then 40 parts of the polyphenyl polymethylene polyisocyanate is added, and the foaming reaction is carried out by rapid stirring, and then the foamed mixture is poured into a mold for curing to obtain a lightweight building thermal insulation board.

[0047] Example 5: The preparation method of the composite phase change material is the same as in Example 3, except that: According to the weight parts, add 50 parts of composite phase change material, 0.5 parts of foaming agent, 0.5 parts of crosslinking agent and 0.1 parts of foam stabilizer to 60 parts of polyether polyol, stir until uniformly mixed, then add 40 parts of polyphenyl polymethylene polyisocyanate, stir quickly to carry out foaming reaction, and then pour the foamed mixture into a mold to cure, thus obtaining a lightweight building thermal insulation board.

[0048] Comparative Example 1: Consistent with Example 1, except that no composite phase change material is added to the lightweight building insulation board.

[0049] Comparative Example 2: Consistent with Example 1, except that the silica aerogel prepared in Example 1 is used instead of the composite phase change material.

[0050] Tests were conducted on Examples 1-5 and Comparative Examples 1 and 2. The specific test contents are as follows: Thermal insulation performance test: The hot plate method was used according to the national standard GB / T 10294. Before testing, a pair of specimens with matching dimensions and flat surfaces were cut from the plate to be tested and placed in a constant temperature and humidity environment for at least 48 hours to acclimatize them and eliminate the influence of historical temperature and humidity. Subsequently, the average thickness and density of the specimens were accurately measured. During the formal test, the two specimens were symmetrically placed against both sides of the central heating unit of the hot plate apparatus, and the required average test temperature was set to 70°C. After starting the equipment, the system precisely controlled the temperature to allow heat to pass vertically through the specimens and continuously monitored until the heat flow and temperature change rate reached a steady state. Under steady-state conditions, the instrument automatically recorded the data and calculated the thermal conductivity of the specimens according to the formula. The test results are shown in Table 1.

[0051] Limiting oxygen index test: The test was conducted according to the national standard GB / T 2406.2. The sample size was 100mm × 10mm × 10mm. Before being placed in the testing instrument, the sample needed to be conditioned for at least 88 hours at 23±2℃ and 50±5% relative humidity. During the test, the sample was vertically fixed in the combustion chamber, and oxygen-nitrogen mixed gases of different concentrations were introduced. The top was ignited using an igniter, and the critical oxygen concentration was determined using the "lifting method". The test results are shown in Table 1.

[0052] Table 1

[0053] Referring to the test results in Table 1, Comparative Example 1, which lacks the composite phase change material compared to Example 3, showed an increase in thermal conductivity from 0.16 W / (m·K) to 0.38 W / (m·K). This indicates that the addition of the composite phase change material can significantly reduce the thermal conductivity of the insulation board and enhance its thermal insulation performance. Simultaneously, the limiting oxygen index decreased from 31.2% to 17.8%, indicating that the addition of the composite phase change material also enhances the flame-retardant effect of the insulation board.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A lightweight building thermal insulation board, characterized in that, include: Polyurethane matrix; as well as A composite phase change material is dispersed in the polyurethane matrix. The composite phase change material comprises silica aerogel and disodium hydrogen phosphate dodecahydrate, wherein the disodium hydrogen phosphate dodecahydrate is loaded in the silica aerogel.

2. The lightweight building thermal insulation board according to claim 1, characterized in that, The mass ratio of the composite phase change material to the polyurethane matrix is ​​1:10 to 5:

10.

3. The lightweight building thermal insulation board according to claim 1, characterized in that, In the composite phase change material, the mass ratio of silica aerogel to disodium hydrogen phosphate dodecahydrate is 5:1 to 3:

1.

4. The lightweight building thermal insulation board according to claim 1, characterized in that, The silica aerogel was prepared from a precursor composed of diphenylmethane bismaleimide and 3-mercaptopropyltriethoxysilane.

5. The lightweight building thermal insulation board according to claim 1, characterized in that, The polyurethane matrix is ​​formed from a reaction system comprising the following components: Polyether polyols; Polyphenyl polymethylene polyisocyanate; Foaming agent; Crosslinking agent; and Foam stabilizer.

6. The lightweight building thermal insulation board according to claim 5, characterized in that, The polyether polyol is polyethylene glycol, the foaming agent is cyclopentane, the crosslinking agent is diethylene glycol, and the foam stabilizer is dimethyl silicone oil.

7. A method for preparing a lightweight building thermal insulation board according to any one of claims 1-6, characterized in that, Includes the following steps: A composite phase change material, a foaming agent, a crosslinking agent, and a foam stabilizer are added to a polyether polyol and stirred until the mixture is homogeneous. Then, polyphenyl polymethylene polyisocyanate is added and stirred rapidly to carry out a foaming reaction. The foamed mixture is then poured into a mold and cured to obtain the lightweight building thermal insulation board.

8. The method for preparing the lightweight building thermal insulation board according to claim 7, characterized in that, The preparation method of the composite phase change material includes the following steps: Dissolve disodium hydrogen phosphate dodecahydrate in deionized water and heat until completely dissolved to obtain a solution. Add silica aerogel to the solution and stir for 30-60 minutes. After stirring, place the mixture in a vacuum drying oven for vacuum drying to obtain the composite phase change material.

9. The method for preparing the lightweight building thermal insulation board according to claim 8, characterized in that, The method for preparing the silica aerogel includes the following steps: Diphenylmethane bismaleimide and 3-mercaptopropyltriethoxysilane were dissolved in tetrahydrofuran, and triethylamine was added as a catalyst. The mixture was stirred at room temperature for 10-12 h to obtain the precursor. The precursor was dissolved in a mixed solvent of ethanol and tetrahydrofuran, deionized water and hydrochloric acid were added, the mixture was stirred until homogeneous, and allowed to stand until gelation was achieved to obtain a gel. The gel was vacuum dried and ground through a 200-mesh sieve to obtain the silica aerogel.

10. The method for preparing the lightweight building thermal insulation board according to claim 8, characterized in that, The molar ratio of diphenylmethane bismaleimide to 3-mercaptopropyltriethoxysilane is from 1:1.8 to 1:2.2.

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