Environment-friendly insulation board and preparation method thereof

Abstract

The invention belongs to the field of building materials, and relates to an environment-friendly insulation board and a preparation method thereof. The environment-friendly insulation board is prepared from the following raw materials: 280 to 400 parts of dihydric phosphate, 130 to 160 parts of magnesium oxide, 3 to 5 parts of retarder, 40 to 70 parts of hydrophobic modified nano clay, 100 to 140 parts of polystyrene foam particles, 200 to 250 parts of water, 20 to 40 parts of basalt chopped fiber and 2 to 8 parts of silane coupling agent. The dihydric phosphate and magnesium oxide system provided by the invention has excellent chemical stability and CO2 erosion resistance, and can effectively prevent efflorescence, crystallization and pulverization in a high-temperature and high-humidity environment. The silane coupling agent can form a bridging structure between an inorganic phase and an organic component, enhance the interface bonding force and reduce microcracks, an interface microcell is filled with the hydrophobically modified nano-clay, a water barrier layer can be formed, and the hydrophobicity of polystyrene foam particles is combined, so that the water absorption rate can be remarkably reduced, and the freeze-thaw durability of the insulation board is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to an environment-friendly insulation board and a preparation method thereof. BACKGROUND

[0002] An insulation board is a kind of building material with low thermal conductivity, usually made of lightweight porous materials or composite structures, such as polystyrene foam board, extruded polystyrene board, rock wool board, foamed cement board, and new nano-composite insulation materials. With the increasing demand for building energy saving, insulation boards have been widely used in the external wall, roof and ground insulation systems of industrial and civil buildings, playing a role in reducing heat transfer and maintaining indoor temperature stability.

[0003] Although insulation boards play a key role in building energy saving, there is a common problem of difficulty in coordinating functionality. Traditional organic insulation boards have excellent insulation performance, but their fireproofing level is usually only B1 grade, which poses a fire hazard. Inorganic insulation boards can achieve A-level fireproofing standards, but their thermal conductivity is relatively high, resulting in relatively poor insulation performance.

[0004] Composite insulation boards developed in recent years attempt to balance the above contradictions. For example, the invention patent with publication number CN113248229A discloses a graphite inorganic composite polystyrene foam insulation board, in which magnesium sulfate, magnesium oxide and water cooperate with each other to form a gel system, making the insulation board have good flame retardant performance. Silicon aerogel and polystyrene foam particles are added to the gel system to reduce its thermal conductivity without compromising its flame retardant performance, so that the insulation board has good insulation performance and flame retardant performance at the same time.

[0005] However, the above technical solution still has the following problems:

[0006] First, the system composed of magnesium sulfate and magnesium oxide is not stable, and it is easy to appear halogen return crystallization phenomenon in long-term hot and humid environment. Free Mg 2+ ions are easy to react with CO2 in the air to form loose basic magnesium carbonate, causing surface powdering and falling off.

[0007] Second, the interface bonding between polystyrene foam particles and inorganic matrix is relatively poor, and a network of micron-sized cracks is easily formed. These small cracks provide a channel for water intrusion, resulting in high water absorption of the insulation board. When subjected to environmental effects such as freeze-thaw cycles, the water infiltrated into the material will undergo repeated freezing and thawing, which will further cause volume expansion and shrinkage changes, resulting in fluctuations in insulation performance. This high water absorption not only affects the stability of the insulation material in low temperature environment, but also further weakens its durability.

[0008] Therefore, it is necessary to provide an insulation board that is resistant to heat and humidity and has good interface bonding. SUMMARY

[0009] (1) Technical issues to be solved

[0010] In view of the above technical problems, in order to solve the problems in the prior art that the insulation board has poor stability in a hot and humid environment, poor interface bonding resulting in high water absorption and weak durability, the present invention provides an environmentally friendly insulation board and a preparation method thereof.

[0011] (2) Technical solution

[0012] In order to achieve the above objectives, the main technical solutions adopted by the present invention include:

[0013] The present invention provides an environmentally friendly thermal insulation board. The raw materials for preparing the environmentally friendly thermal insulation board include, by weight, 280-400 parts of dihydrogen phosphate, 130-160 parts of magnesium oxide, 3-5 parts of a retarder, 40-70 parts of hydrophobically modified nanoclay, 100-140 parts of polystyrene foam particles, 200-250 parts of water, 20-40 parts of basalt chopped fibers, and 2-8 parts of a silane coupling agent.

[0014] In the environmentally friendly thermal insulation board as described above, preferably, the dihydrogen phosphate is potassium dihydrogen phosphate or sodium dihydrogen phosphate.

[0015] In the environmentally friendly thermal insulation board as described above, preferably, the retarder is borax, citric acid or sodium hexametaphosphate.

[0016] In the environmentally friendly thermal insulation board as described above, preferably, the average diameter of the chopped basalt fibers is 10-15 μm, and the average length is 6-10 mm.

[0017] For the environmentally friendly thermal insulation board as described above, preferably, the preparation method of the hydrophobically modified nanoclay is as follows:

[0018] Nano-sized sodium montmorillonite powder is dispersed in deionized water to obtain a sodium montmorillonite slurry; an ethanol solution of hexadecyltrimethoxysilane is added to the sodium montmorillonite slurry under stirring conditions, and the mixture is continuously stirred and reacted at a certain temperature. After filtering, washing, and drying, hydrophobically modified nanoclay is obtained.

[0019] In the environmentally friendly thermal insulation board as described above, preferably, the mass ratio of hexadecyltrimethoxysilane to nano-scale sodium montmorillonite powder is 0.05-0.1:1, and the particle size of the nano-scale sodium montmorillonite powder is 100-200 nm;

[0020] Add the ethanol solution of hexadecyltrimethoxysilane to the sodium montmorillonite slurry and stir continuously at 60-80° C. for 3-6 hours.

[0021] The environmentally friendly insulation board as described above, preferably, in the polystyrene foam particles, the particles with an average particle size of 0.5-1mm account for 35-45wt%, the particles with an average particle size of 1-3mm account for 30-40wt%, and the particles with an average particle size of 3-5mm account for 20-30wt%.

[0022] The environmentally friendly insulation board as described above, preferably, the silane coupling agent is a mixture of KH550 and KH560, and the mass ratio of KH550 to KH560 is 1:2-2:1.

[0023] The present application also provides a preparation method of the above-mentioned environmentally friendly insulation board, comprising the following steps:

[0024] S1: Dissolve the dihydrogen phosphate salt in water, add magnesium oxide and a retarder, and stir uniformly to obtain a gel;

[0025] S2: Add the silane coupling agent, the hydrophobically modified nanoclay and the basalt short-cut fiber into the gel, and stir uniformly to obtain a mixture;

[0026] S3: Stir the polystyrene foam particles and the mixture uniformly, pour into a mold, and pressurize and form under a pressure of 2-5MPa, then demold, steam cure at 35-45℃ for 24-48h, and dry to obtain the environmentally friendly insulation board.

[0027] (III) Beneficial effects

[0028] Firstly, the dihydrogen phosphate salt and magnesium oxide are used as the inorganic gelling system in the present application, and compared with the traditional magnesium sulfate and magnesium oxide system, the dihydrogen phosphate salt and magnesium oxide system has higher chemical stability and CO2 corrosion resistance, which effectively prevents the halogen return and surface powdering of the insulation material in the long-term high-temperature and high-humidity environment.

[0029] Secondly, the silane coupling agent and the hydrophobically modified nanoclay are introduced to cooperate in the present application. The silane coupling agent can be chemically bonded with the polystyrene foam particles and the dihydrogen phosphate salt matrix respectively, forming a bridging structure of "inorganic phase-coupling agent-organic component", which greatly enhances the interfacial bonding force and effectively improves the microcrack network problem caused by poor interfacial bonding of the traditional composite insulation board. The nanoclay filled in the organic / inorganic interface microzone after hydrophobic treatment has excellent hydrophobic properties, which can form a water barrier layer on the pore wall surface of the insulation board, combined with the hydrophobicity of the polystyrene foam particles, to reduce the water absorption of the insulation material and effectively block the water intrusion channel through the crack network, thereby significantly improving the durability of the insulation material in the freeze-thaw environment. Through detection, the volume water absorption of the insulation board of the present application is less than 3%, the thermal conductivity fluctuation is less than 3% after 20 freeze-thaw cycles, and the compressive strength loss rate is less than 7%, which significantly improves the stability and durability of the insulation board in the low-temperature environment.

[0030] Thirdly, the present application also constructs a through type reinforcing network structure by adding basalt short fibers, which can not only improve the bending resistance and fracture toughness of the thermal insulation board, but also effectively inhibit the expansion of micro-cracks through crack deflection effect, thereby improving the overall mechanical properties and structural integrity. DETAILED DESCRIPTION

[0031] In order to better explain the present application, the present application is described in detail below in combination with specific embodiments.

[0032] The present application provides an environment-friendly thermal insulation board, according to weight parts, the preparation raw materials of the environment-friendly thermal insulation board include 280-400 parts of dihydrogen phosphate, 130-160 parts of magnesium oxide, 3-5 parts of a retarder, 40-70 parts of hydrophobically modified nano-clay, 100-140 parts of polystyrene foam particles, 200-250 parts of water, 20-40 parts of basalt short fibers and 2-8 parts of silane coupling agent.

[0033] The present application uses dihydrogen phosphate and magnesium oxide as an inorganic cementing system, compared with the traditional magnesium sulfate and magnesium oxide system, the dihydrogen phosphate and magnesium oxide system of the present application has higher chemical stability and CO2 corrosion resistance, effectively preventing the halogen return crystallization and surface powdering phenomenon of the thermal insulation material in the long-term high temperature and high humidity environment. It is verified by accelerated aging test that after being stored for 90 days under the condition of 70 DEG C and 95 RH% relative humidity, the material surface does not show any crystallization or powdering, the compressive strength retention rate is more than 95%, which fully reflects its superior hygrothermal stability.

[0034] The present application introduces silane coupling agent and hydrophobically modified nano-clay for synergistic effect. Among them, the silane coupling agent can be chemically bonded with the polystyrene foam particles and the dihydrogen phosphate matrix respectively, forming a bridging structure of "inorganic phase-coupling agent-organic component", greatly enhancing the interfacial bonding force, and effectively improving the microcrack network problem of the traditional composite thermal insulation board caused by poor interfacial bonding. The nano-clay treated by hydrophobicity is filled in the organic / inorganic interface micro area, and its excellent hydrophobic property can form a water barrier layer on the pore wall surface of the thermal insulation board, combined with the hydrophobicity of the polystyrene foam particles, to reduce the water absorption of the thermal insulation material, and effectively block the water intrusion channel through the crack network, thereby significantly improving the durability of the thermal insulation material in the freeze-thaw environment. The volume water absorption of the thermal insulation board of the present application is less than 3%, after 20 freeze-thaw cycles, the thermal conductivity fluctuation is less than 3%, and the compressive strength loss rate is less than 7%, which significantly improves the stability and durability of the thermal insulation board in low temperature environment.

[0035] The application also constructs a through type reinforcing network structure by adding basalt short fibers, which can not only improve the bending resistance and fracture toughness of the insulation board, but also effectively inhibit the expansion of micro-cracks through crack deflection effect, and improve the overall mechanical properties and structural integrity.

[0036] The insulation board has excellent thermal insulation performance and flame retardant performance, the fireproof grade of which can reach A1 level, the thermal conductivity is less than or equal to 0.033 W / (m·K), the compressive strength is greater than or equal to 0.3 MPa, the volume water absorption of the insulation board is less than 3%, and after 20 freeze-thaw cycles, the fluctuation of the thermal conductivity is less than 3%, and the loss rate of the compressive strength is less than 7%.

[0037] Preferably, the dihydrogen phosphate in the application can be potassium dihydrogen phosphate or sodium dihydrogen phosphate, and the retarder is used to control the reaction rate between the dihydrogen phosphate and magnesium oxide, so as to avoid rapid condensation leading to uneven structure or internal stress concentration, and can specifically select borax, citric acid or sodium hexametaphosphate.

[0038] Preferably, the average diameter of the basalt short fiber is 10-15 μm, and the average length is 6-10 mm. If the diameter of the basalt short fiber is too small, it is easy to be wrapped and invalid, and if the diameter is too large, the dispersibility is reduced, and the diameter range of 10-15 μm can balance the interfacial bonding force and the dispersibility. If the length of the basalt short fiber is too small, it may be difficult to cross the micro-cracks, and if the length is too long, it is easy to agglomerate and be broken during pressing.

[0039] Preferably, the preparation method of the hydrophobically modified nano clay in the application is as follows:

[0040] The nanoscale sodium-based montmorillonite powder is dispersed in deionized water to obtain a sodium-based montmorillonite slurry, wherein the mass ratio of hexadecyl trimethoxysilane to nanoscale sodium-based montmorillonite powder is 0.05-0.1:1, and the particle size of the nanoscale sodium-based montmorillonite powder is 100-200 nm. The ethanol solution of hexadecyl trimethoxysilane is added to the sodium-based montmorillonite slurry under stirring, and the continuous stirring reaction is carried out at 60-80 DEG C for 3-6 h, and the hydrophobically modified nano clay is obtained after filtration, washing and drying.

[0041] When the hexadecyl trimethoxysilane is added to the aqueous sodium-based montmorillonite slurry, the hexadecyl trimethoxysilane will hydrolyze and condense with the hydroxyl groups on the surface of the sodium-based montmorillonite to form a covalent bond. With the reaction, the long-chain alkyl group of hexadecyl trimethoxysilane gradually covers the surface of the sodium-based montmorillonite, giving it new hydrophobic properties.

[0042] Preferably, in the polystyrene foam particles, the particles with an average particle size of 0.5-1 mm account for 35-45 wt%, the particles with an average particle size of 1-3 mm account for 30-40 wt%, and the particles with an average particle size of 3-5 mm account for 20-30 wt%. The present application forms a more compact and effective multi-level pore structure inside the insulation board by mixing particles of different sizes. Smaller particles can fill the gaps between larger particles, while larger particles provide the main skeleton support. This combination helps to reduce the ineffective space in porosity and improve the stability of the material.

[0043] Further preferably, the silane coupling agent of the present application is a mixture of KH550 and KH560, and the mass ratio of KH550 to KH560 is 1:2-2:1.

[0044] The present application also provides a preparation method of the environment-friendly insulation board, comprising the following steps:

[0045] S1: Dissolve the dihydrogen phosphate salt in water, add magnesium oxide and a retarder, and stir uniformly to obtain a gel.

[0046] S2: Add the silane coupling agent, the hydrophobically modified nano-clay, and the basalt short-cut fiber to the gel, and stir uniformly to obtain a mixture.

[0047] S3: Stir the polystyrene foam particles and the mixture uniformly, pour into a mold, press and form under a pressure of 2-5 MPa, steam cure at 35-45℃ for 24-48 h after demolding, and dry to obtain the environment-friendly insulation board.

[0048] In order to further clarify the present application and its technical progress, the following specific examples and technical effects are described.

[0049] Example 1

[0050] The present application provides a preparation method of the environment-friendly insulation board, comprising the following steps:

[0051] S1: Dissolve 340 parts of potassium dihydrogen phosphate in 225 parts of water, add 150 parts of magnesium oxide and 4 parts of borax, and stir uniformly to obtain a gel.

[0052] S2: Add 5 parts of silane coupling agent, 55 parts of hydrophobically modified nano-clay, and 30 parts of basalt short-cut fiber to the gel, and stir uniformly to obtain a mixture. The average diameter of the basalt short-cut fiber is 12 μm, and the average length is 8 mm.

[0053] S3: Stir 120 parts of polystyrene foam particles and the mixture uniformly, pour into a mold, press and form under a pressure of 3 MPa, steam cure at 40℃ for 36 h after demolding, and dry to obtain the environment-friendly insulation board.

[0054] The polystyrene foam particles in this embodiment include 40 wt% of particles with an average particle size of 0.5-1 mm, 35 wt% of particles with an average particle size of 1-3 mm, and 25 wt% of particles with an average particle size of 3-5 mm. The silane coupling agent in this embodiment is a mixture of KH550 and KH560, and the mass ratio of KH550 to KH560 is 1:1.

[0055] The method for preparing the hydrophobically modified nanoclay is as follows:

[0056] The nanoscale sodium-based montmorillonite powder is dispersed in deionized water to obtain a sodium-based montmorillonite slurry, wherein the mass ratio of hexadecyl trimethoxysilane to the nanoscale sodium-based montmorillonite powder is 0.08:1, and the average particle size of the nanoscale sodium-based montmorillonite powder is 150 nm. The ethanol solution of hexadecyl trimethoxysilane is added to the sodium-based montmorillonite slurry under stirring, and continuous stirring reaction is carried out at 70℃ for 4 h. After filtration, washing, and drying, the hydrophobically modified nanoclay is obtained.

[0057] Example 2

[0058] The embodiment provides a preparation method of an environmentally-friendly thermal insulation board, which comprises the following steps:

[0059] S1: 280 parts of sodium dihydrogen phosphate are dissolved in 200 parts of water, 130 parts of magnesium oxide and 3 parts of citric acid are added, and stirring is uniformly carried out to obtain a gel.

[0060] S2: 2 parts of a silane coupling agent, 40 parts of the hydrophobically modified nanoclay, and 20 parts of basalt short-cut fibers are added to the gel, and stirring is uniformly carried out to obtain a mixture. The average diameter of the basalt short-cut fibers is 10 μm, and the average length is 6 mm.

[0061] S3: 10 parts of polystyrene foam particles are uniformly stirred with the mixture, injected into a mold, and pressed and formed under a pressure of 2 MPa. After demolding, steam curing is carried out at 35℃ for 24 h, and drying is carried out to obtain the environmentally-friendly thermal insulation board.

[0062] The polystyrene foam particles in this embodiment include 40 wt% of particles with an average particle size of 0.5-1 mm, 35 wt% of particles with an average particle size of 1-3 mm, and 25 wt% of particles with an average particle size of 3-5 mm. The silane coupling agent in this embodiment is a mixture of KH550 and KH560, and the mass ratio of KH550 to KH560 is 1:1.

[0063] The method for preparing the hydrophobically modified nanoclay is as follows:

[0064] The nanoscale sodium-based montmorillonite powder is dispersed in deionized water to obtain a sodium-based montmorillonite slurry, wherein the mass ratio of hexadecyl trimethoxysilane to the nanoscale sodium-based montmorillonite powder is 0.05:1, and the average particle size of the nanoscale sodium-based montmorillonite powder is 100 nm. The ethanol solution of hexadecyl trimethoxysilane is added to the sodium-based montmorillonite slurry under stirring, and the reaction is continuously stirred at 60°C for 3 h. After filtration, washing, and drying, the hydrophobically modified nanoclay is obtained.

[0065] Example 3

[0066] The present embodiment provides a preparation method of an environmentally friendly insulation board, comprising the following steps:

[0067] S1: 400 parts of potassium dihydrogen phosphate are dissolved in 250 parts of water, 160 parts of magnesium oxide and 5 parts of sodium hexametaphosphate are added, and the mixture is stirred uniformly to obtain a gel.

[0068] S2: 8 parts of a silane coupling agent, 70 parts of hydrophobically modified nanoclay, and 40 parts of basalt chopped fiber are added to the gel, and the mixture is stirred uniformly to obtain a mixture. The average diameter of the basalt chopped fiber is 15 μm, and the average length is 10 mm.

[0069] S3: 140 parts of polystyrene foam particles are uniformly stirred with the mixture, injected into a mold, and pressed into shape under a pressure of 5 MPa. After demolding, the mixture is steam cured at 45°C for 48 h, and then dried to obtain an environmentally friendly insulation board.

[0070] In the polystyrene foam particles of the present embodiment, the particles with an average particle size of 0.5-1 mm account for 45 wt%, the particles with an average particle size of 1-3 mm account for 30 wt%, and the particles with an average particle size of 3-5 mm account for 25 wt%. The silane coupling agent of the present embodiment is a mixture of KH550 and KH560, and the mass ratio of KH550 to KH560 is 2:1.

[0071] The preparation method of the hydrophobically modified nanoclay is as follows:

[0072] The nanoscale sodium-based montmorillonite powder is dispersed in deionized water to obtain a sodium-based montmorillonite slurry, wherein the mass ratio of hexadecyl trimethoxysilane to the nanoscale sodium-based montmorillonite powder is 0.1:1, and the average particle size of the nanoscale sodium-based montmorillonite powder is 200 nm. The ethanol solution of hexadecyl trimethoxysilane is added to the sodium-based montmorillonite slurry under stirring, and the reaction is continuously stirred at 80°C for 6 h. After filtration, washing, and drying, the hydrophobically modified nanoclay is obtained.

[0073] Example 4

[0074] The present embodiment provides a preparation method of an environmentally friendly insulation board, comprising the following steps:

[0075] S1: 300 parts of potassium dihydrogen phosphate was dissolved in 210 parts of water, 145 parts of magnesium oxide and 3.5 parts of citric acid were added, and a gel was obtained after stirring uniformly.

[0076] S2: 4 parts of silane coupling agent, 50 parts of hydrophobically modified nanoclay and 25 parts of basalt chopped fiber were added into the gel, and a mixture was obtained after stirring uniformly. The basalt chopped fiber had an average diameter of 11 μm and an average length of 7 mm.

[0077] S3: 110 parts of polystyrene foam particles were stirred uniformly with the mixture, injected into a mold, and molded by pressing under a pressure of 3.3 MPa. After demolding, steam curing was performed at 38°C for 28 h, and an environmentally friendly insulation board was obtained after drying.

[0078] In the polystyrene foam particles of this embodiment, particles with an average particle size of 0.5-1 mm accounted for 40 wt%, particles with an average particle size of 1-3 mm accounted for 40 wt%, and particles with an average particle size of 3-5 mm accounted for 20 wt%. The silane coupling agent of this embodiment was a mixture of KH550 and KH560, and the mass ratio of KH550 to KH560 was 1:2.

[0079] In this embodiment, the hydrophobically modified nanoclay was prepared by the same method as in Example 1.

[0080] Example 5

[0081] This embodiment provides a method for preparing an environmentally friendly insulation board, comprising the following steps:

[0082] S1: 320 parts of potassium dihydrogen phosphate was dissolved in 240 parts of water, 135 parts of magnesium oxide and 5 parts of citric acid were added, and a gel was obtained after stirring uniformly.

[0083] S2: 7 parts of silane coupling agent, 60 parts of hydrophobically modified nanoclay and 35 parts of basalt chopped fiber were added into the gel, and a mixture was obtained after stirring uniformly. The basalt chopped fiber had an average diameter of 13 μm and an average length of 8 mm.

[0084] S3: 130 parts of polystyrene foam particles were stirred uniformly with the mixture, injected into a mold, and molded by pressing under a pressure of 2.5 MPa. After demolding, steam curing was performed at 37°C for 48 h, and an environmentally friendly insulation board was obtained after drying.

[0085] The polystyrene foam particles in this embodiment have 40 wt% of particles with an average particle size of 0.5-1 mm, 30 wt% of particles with an average particle size of 1-3 mm, and 30 wt% of particles with an average particle size of 3-5 mm. The silane coupling agent in this embodiment is a mixture of KH550 and KH560, and the mass ratio of KH550 to KH560 is 2:1.

[0086] In this embodiment, the hydrophobically modified nanoclay is prepared by the same method as in Example 1.

[0087] Comparative Example 1

[0088] This comparative example provides a method for preparing an environmentally friendly insulation board, which differs from Example 1 in that no silane coupling agent is added.

[0089] Comparative Example 2

[0090] This comparative example provides a method for preparing an environmentally friendly insulation board, which differs from Example 1 in that no hydrophobically modified nanoclay is added.

[0091] Comparative Example 3

[0092] This comparative example provides a method for preparing an environmentally friendly insulation board, which differs from Example 1 in that no basalt short fiber is added.

[0093] The fire resistance, thermal conductivity, compressive strength, and water absorption of the insulation boards prepared in Examples 1-5 and Comparative Examples 1-3 are detected, and Table 1 is obtained.

[0094] Table 1: Performance statistics of the insulation boards prepared in Examples 1-5 and Comparative Examples 1-3

[0095]

[0096]

[0097] As can be seen from Table 1, in Comparative Example 1, the interface microcracks increase due to the absence of silane coupling agent, causing some organic components to be exposed, increasing the local burning behavior, and reducing the fire resistance of the insulation board from A1 to A2. At the same time, the thermal conductivity increases slightly, and the compressive strength decreases significantly due to the poor organic / inorganic interface bonding, and the water absorption increases. In Comparative Example 2, the absence of hydrophobically modified nanoclay causes the organic / inorganic interface microzone to lack fillers, resulting in a decrease in compressive strength, and the inability to form a water barrier layer, resulting in a significant increase in water absorption. In Comparative Example 3, the absence of basalt short fibers significantly reduces the compressive strength, and slightly increases the water absorption.

[0098] The thermal conductivity fluctuation rate and the compressive strength loss rate of the thermal insulation boards prepared in Examples 1-5 and Comparative Examples 1-3 were detected after 20 freeze-thaw cycles, and the results are shown in Table 2.

[0099] Table 2 Freeze-thaw durability statistics of the thermal insulation boards prepared in Examples 1-5 and Comparative Examples 1-3

[0100]

[0101] The thermal conductivity fluctuation rate of the thermal insulation boards of Examples 1-5 was less than 3% and the compressive strength loss rate was less than 7% after 20 freeze-thaw cycles, while the thermal conductivity fluctuation rate and the compressive strength loss rate of the thermal insulation boards of Comparative Examples 1-3 were significantly higher than those of Examples 1-5.

[0102] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An environmentally friendly insulation board, characterized in that: Calculated by weight, the raw materials for preparing the environmentally friendly insulation board include 280-400 parts of dihydrogen phosphate, 130-160 parts of magnesium oxide, 3-5 parts of retarder, 40-70 parts of hydrophobically modified nanoclay, 100-140 parts of polystyrene foam particles, 200-250 parts of water, 20-40 parts of basalt chopped fibers, and 2-8 parts of silane coupling agent.

2. The environmentally friendly insulation board according to claim 1, characterized in that: The dihydrogen phosphate is potassium dihydrogen phosphate or sodium dihydrogen phosphate.

3. The environmentally friendly insulation board according to claim 1, characterized in that: The retarder is borax, citric acid or sodium hexametaphosphate.

4. The environmentally friendly insulation board according to claim 1, characterized in that: The average diameter of the basalt chopped fibers is 10-15 μm, and the average length is 6-10 mm.

5. The environmentally friendly thermal insulation board according to claim 1, characterized in that: The preparation method of hydrophobically modified nanoclay is as follows: Nano-sized sodium montmorillonite powder is dispersed in deionized water to obtain a sodium montmorillonite slurry; an ethanol solution of hexadecyltrimethoxysilane is added to the sodium montmorillonite slurry under stirring conditions, and the mixture is continuously stirred and reacted at a certain temperature. After filtering, washing, and drying, hydrophobically modified nanoclay is obtained.

6. The environmentally friendly thermal insulation board according to claim 5, characterized in that: The mass ratio of hexadecyltrimethoxysilane to nano-sized sodium montmorillonite powder is 0.05-0.1:1, and the particle size of the nano-sized sodium montmorillonite powder is 100-200 nm; Add the ethanol solution of hexadecyltrimethoxysilane to the sodium montmorillonite slurry and stir continuously at 60-80° C. for 3-6 hours.

7. The environmentally friendly thermal insulation board according to claim 1, characterized in that: Among the polystyrene foam particles, particles with an average particle size of 0.5-1 mm account for 35-45 wt%, particles with an average particle size of 1-3 mm account for 30-40 wt%, and particles with an average particle size of 3-5 mm account for 20-30 wt%.

8. The environmentally friendly thermal insulation board according to claim 1, characterized in that: The silane coupling agent is a mixture of KH550 and KH560, and the mass ratio of KH550 to KH560 is 1:2-2:

1.

9. A method for preparing the environmentally friendly thermal insulation board according to any one of claims 1 to 8, characterized in that: The steps include: S1: dissolving dihydrogen phosphate in water, adding magnesium oxide and retarder, and stirring evenly to obtain a gel; S2: adding a silane coupling agent, hydrophobically modified nanoclay, and basalt chopped fibers to the gel and stirring to obtain a mixture; S3: The polystyrene foam particles are mixed evenly with the mixture, injected into a mold, and pressed into shape at a pressure of 2-5 MPa. After demolding, the mixture is steam-cured at 35-45°C for 24-48 hours, and dried to obtain an environmentally friendly insulation board.

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