Low-density high-strength thermal insulation board and method for manufacturing the same

Abstract

The application discloses a kind of low-density high-strength heat insulation plate and preparation method thereof, the low-density high-strength heat insulation plate includes the following mass percentage of components: poly (4-methyl-1-pentene) 40%~80%, hollow glass microsphere 1%~40%, natural fiber 1%~40%, coupling agent 0.1%~2%.The application selects hollow glass microsphere to reduce the specific gravity and thermal conductivity of poly (4-methyl-1-pentene), improve the hardness and high temperature resistance of TPX, reduce the breakage rate of hollow glass microsphere by natural fiber, so that the heat insulation plate prepared can be used at high temperature (≥150 DEG C), and has the performance of recyclable, light, low thermal conductivity, low deformation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermoplastic polymer material modification, and particularly relates to a low-density high-strength heat insulation plate and a preparation method thereof. BACKGROUND

[0002] Heat insulation plates are often used in aerospace, automobiles, buildings and homes. The existing heat insulation plates commonly use phenolic resin and other thermosetting resins. Thermosetting resins are not environmentally friendly and are difficult to recycle and reuse. The density of thermoplastic plates such as nylon, polycarbonate and ABS plates is too large, and they are not popular in the era of pursuing lightweight. The strength of micro-foamed plastic is not enough, which limits the application of thermoplastic resins in lightweight heat insulation plates.

[0003] Poly(4-methyl-1-pentene) is abbreviated as TPX, which is a polymer of 4-methyl-pentene produced by Mitsui Chemicals Co., Ltd. of Japan. The density of TPX ranges from 0.82 to 0.83 g / cm 3 , which is the lowest density plastic. The water absorption rate is extremely low, which is 0.01%. The Vicat softening point is between 160 DEG C and 170 DEG C. Lightweight, heat resistance, transparency and easy peelability are the most obvious characteristics of TPX.

[0004] Hollow glass microspheres are hollow spheres made of borosilicate glass, which have low density, high strength, self-lubrication, heat insulation, corrosion resistance, fire resistance and other characteristics, and are widely used in heat insulation and sound insulation materials. Hollow glass microspheres can be combined with thermosetting resins and thermoplastic resins to reduce the density of the resins. When blended with engineering plastics, the isotropy of hollow microspheres can also improve the surface leveling of the product, and can alleviate the phenomenon of fiber exposure in the product.

[0005] However, in fact, when hollow glass microspheres are blended with plastics during processing, they often do not reduce the density, but rather increase the density of the plastics. This is because the hollow glass microspheres are broken during the extrusion process, which increases the density of the material. The pressure that hollow glass microspheres can withstand is currently tested in a laboratory environment. However, in actual production, the extrusion and shearing of the hollow glass microspheres by the screw is the main cause of their breakage, because the hollow glass microspheres have a small stress area and a high probability of breakage under this condition. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the technical defects of the background art and provide a low-density high-strength heat insulation plate and a preparation method thereof. In order to design a low-density high-strength heat insulation plate, the present application provides a TPX heat insulation plate, which has the properties of lightweight, high strength and low thermal conductivity. Through the improvement of the process end, the integrity of the hollow glass microspheres is maintained.

[0007] The present application solves the above technical problems by adopting the technical scheme as follows:

[0008] A low-density high-strength thermal insulation board, comprising the following components by mass percentage:

[0009]

[0010] Preferably, the low-density high-strength thermal insulation board comprises the following components by mass percentage:

[0011]

[0012] More preferably, the low-density high-strength thermal insulation board comprises the following components by mass percentage:

[0013]

[0014] Preferably, the compressive strength (80% retention) of the hollow glass microsphere is ≥ 20 MPa.

[0015] Preferably, the natural fiber is selected from any one or both of bamboo fiber and corn straw fiber.

[0016] Preferably, the coupling agent is selected from any one or more of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

[0017] A preparation method of a low-density high-strength thermal insulation board as described above, comprising the following steps:

[0018] (1) Put the natural fiber into a dehumidifying drying box for drying; put the hollow glass microsphere into a dehumidifying drying box for drying;

[0019] (2) Weigh poly(4-methyl-1-pentene) and natural fiber according to the weight ratio, and put them into a high-speed mixer for uniform mixing;

[0020] (3) Take out the mixed material of step (2), and place it in a co-rotating twin-screw extruder for extrusion and granulation to obtain blended granules;

[0021] (4) Put the blended granules obtained in step (3) into a liquid nitrogen freezing mill for freezing and grinding, and screen the blended powder with a mesh size > 40 mesh using a screen;

[0022] (5) Put the dried hollow glass microspheres of step (1) into an ethanol aqueous solution, add the weighed coupling agent, and ultrasonically disperse. After filtration, dry the dispersed hollow glass microspheres;

[0023] (6) Put the blended powder obtained in step (4) and the hollow glass microspheres obtained in step (5) into a tumbling mixer and mix uniformly;

[0024] (7) Put the mixture obtained in step (6) into a mold, and press into a plate material in a mold pressing machine to obtain a low-density high-strength thermal insulation plate.

[0025] Preferably, in step (1), the temperature during drying of the natural fibers is set to 60-120℃, and the duration is 2-12h.

[0026] Preferably, in step (1), the temperature during drying of the hollow glass microspheres is set to 100-150℃, and the duration is 2-12h.

[0027] Preferably, in step (2), the rotation speed of the high-speed mixer is set to 100-600rpm, and the high-speed stirring is performed for 2-30min.

[0028] Preferably, in step (3), the rotation speed of the extruder is set to 100-400rpm, the extrusion temperature is set to 150-300℃, and the die temperature is set to 100-300℃.

[0029] Preferably, in step (5), the concentration of the aqueous ethanol solution is 90wt%.

[0030] Preferably, in step (5), the ultrasonic dispersion conditions are 60-120℃, and the dispersion is performed for 1-10h.

[0031] Preferably, in step (5), the drying temperature is set to 80-150℃, and the duration is 30-240min.

[0032] Preferably, in step (6), the rotation speed of the tumbling mixer is set to 10-60rpm, and the mixing time is set to 5-20min.

[0033] Preferably, in step (7), the mold pressing temperature of the mold pressing machine is set to 200-250℃, and the mold pressing time is set to 20-180min.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] (1) Hollow glass microspheres are easily broken under the shearing action of the screw, and the present application does not place the hollow glass microspheres in the extruder for shearing, but only performs one hot-pressing molding, thereby maximizing the integrity of the hollow glass microspheres;

[0036] (2) The true density of natural fibers is low (0.5-0.7g / cm 3 ), which not only reduces the density of TPX, but also enhances the mechanical strength of TPX and improves the heat resistance of TPX;

[0037] (3) Hollow glass microspheres are broken by extrusion with each other, and the natural fibers can buffer the hollow glass microspheres and reduce the breakage of the hollow glass microspheres during the extrusion;

[0038] (4) The natural fibers and the plastic are hot-pressed to form a product, and the product is broken due to the uneven distribution of the fibers and the stress concentration; the natural fibers are first blended with the TPX resin and then hot-pressed with the hollow glass microspheres, and the fibers are uniformly distributed in the plate prepared by the process;

[0039] (5) The TPX and the hollow glass microspheres are combined to reduce the toughness of the material, greatly increase the notch sensitivity of the composite material, and easily break when the material is damaged and subjected to an instantaneous impact; the inorganic fibers have a high aspect ratio and are embedded in the TPX resin, and the composite material can pull the resin when it is cracked to reduce the notch sensitivity of the composite material;

[0040] (6) The ordinary grinding machine generates a large amount of heat during operation, which causes the degradation of the high molecular material during grinding, and the natural fibers are easily yellowed or blackened due to heating during grinding; the liquid nitrogen grinding technology is selected to maximize the integrity of the molecular chains of the TPX plastic and the natural fibers, and the natural fibers are not yellowed or blackened during grinding. DETAILED DESCRIPTION

[0041] In order to better understand the content of the present application, the following further describes in combination with specific examples. It should be understood that these examples are only used to further illustrate the present application, and are not used to limit the scope of the present application. In addition, it should be understood that after reading the content described in the present application, the person skilled in the art makes some non-essential modifications or adjustments to the present application, which still belongs to the protection scope of the present application.

[0042] Example 1

[0043] A low-density high-strength thermal insulation plate is composed of the following components:

[0044]

[0045] The poly(4-methyl-1-pentene) selected in the embodiment is purchased from Mitsui Chemical, and the brand is RT18, the density is 0.833 g / cm 3 ; the hollow glass microspheres are purchased from Maanshan Mining Institute New Material Technology Co., Ltd. of China Steel Group, and the brand is 32P4000, the true density is 0.32 g / cm 3 , and the compressive strength (80% retention) is 28 MPa; the true density of the bamboo fiber is 0.679 g / cm 3 .

[0046] The preparation method of the low-density high-strength thermal insulation plate as described above is as follows:

[0047] (1) Bamboo fibers were placed in a dehumidifying drying oven and dried at a temperature of 80°C for 4h. Hollow glass microspheres were placed in a dehumidifying drying oven and dried at a temperature of 120°C for 4h;

[0048] (2) Poly(4-methyl-1-pentene) and bamboo fibers were weighed according to the weight ratio and put into a high-speed mixer, and the rotation speed of the high-speed mixer was set to 200 rpm, and high-speed stirring was performed for 5 min;

[0049] (3) The mixed material of step (2) was taken out and placed in a co-rotating twin-screw extruder, and the rotation speed of the extruder was set to 200 rpm, the extrusion temperature was set to 200°C, and the die temperature was set to 190°C to obtain blended granules;

[0050] (4) The blended granules obtained in step (3) were ground by a liquid nitrogen cryogenic mill, and the blended powder with a mesh size of >40 meshes was screened out;

[0051] (5) The hollow glass microspheres dried in step (1) were placed in a 90wt% ethanol aqueous solution, and a weighed silane coupling agent KH550 was added, and ultrasonic dispersion was performed at 80°C for 2h. The dispersed hollow glass microspheres were filtered and dried for 120 min at a temperature of 120°C;

[0052] (6) The blended powder obtained in step (4) and the hollow glass microspheres obtained in step (5) were placed in a tumbling mixer, and the rotation speed was set to 20 rpm, and the mixing time was set to 10 min;

[0053] (7) The mixed material obtained in step (6) was placed in a mold, and a plate material was pressed in a mold pressing machine, and the mold pressing temperature was set to 220°C, and the mold pressing time was set to 60 min, to obtain a low-density high-strength thermal insulation plate;

[0054] (8) The low-density high-strength thermal insulation plate obtained in step (7) was punched into a standard sample bar for testing.

[0055] Example 2

[0056] A low-density high-strength thermal insulation plate, which is composed of the following components:

[0057]

[0058] The poly(4-methyl-1-pentene) used in this example was purchased from Mitsui Chemical, with a brand name of RT18, and a density of 0.833 g / cm 3 ; The hollow glass microspheres were purchased from Maanshan Mining Institute New Material Technology Co., Ltd. of China Steel Group, with a brand name of GS40, and a true density of 0.4 g / cm 3, compressive strength (80% retention) 28 MPa; corn stalk fiber true density 0.811 g / cm 3 .

[0059] A method for preparing a low-density high-strength thermal insulation board as described above, the steps being as follows:

[0060] (1) Dry the corn stalk fibers in a desiccator at a temperature of 70°C for 6 hours. Dry the hollow glass microspheres in a desiccator at a temperature of 120°C for 6 hours;

[0061] (2) Weigh the poly(4-methyl-1-pentene) and corn stalk fibers according to the weight ratio, and place them in a high-speed mixer. Set the speed of the high-speed mixer to 300 rpm, and stir at high speed for 10 minutes;

[0062] (3) Take out the mixed material from step (2) and place it in a co-rotating twin-screw extruder. Set the speed of the extruder to 250 rpm, the extrusion temperature to 200°C, and the die temperature to 190°C. Obtain the blended granules;

[0063] (4) Grind the blended granules obtained in step (3) in a liquid nitrogen cryogenic grinder, and screen the blended powder with a mesh size of >40 mesh using a screen;

[0064] (5) Place the dried hollow glass microspheres from step (1) in a 90wt% ethanol aqueous solution, and add the weighed silane coupling agent KH560. Ultrasonically disperse at 90°C for 2 hours. Dry the dispersed hollow glass microspheres by suction filtration for 120 minutes at a temperature of 120°C;

[0065] (6) Place the blended powder from step (4) and the hollow glass microspheres from step (5) in a tumbling mixer. Set the speed to 15 rpm, and mix for 15 minutes;

[0066] (7) Place the mixed material from step (6) in a mold, and press it into a board material in a molding machine. Set the molding temperature to 220°C, and the molding time to 60 minutes. Obtain the low-density high-strength thermal insulation board;

[0067] (8) Punch the low-density high-strength thermal insulation board obtained in step (7) into standard samples for testing.

[0068] Example 3

[0069] A low-density high-strength thermal insulation board, composed of the following components:

[0070]

[0071] The poly(4-methyl-1-pentene) selected in this embodiment is purchased from Mitsui Chemical, with the trade name DX820, and the density is 0.832 g / cm 3 ; the hollow glass microbeads are purchased from Maanshan Mining Institute New Material Technology Co., Ltd. of China Steel Group, with the trade name 38P5500, and the true density is 0.38 g / cm 3 , and the compressive strength (80% retention) is 38 MPa; the true density of the bamboo fiber is 0.679 g / cm 3 .

[0072] The preparation method of the low-density high-strength thermal insulation board as described above, the steps are as follows:

[0073] (1) The bamboo fiber is placed in a desiccator for drying, and the drying temperature is set to 80℃, and the time is 4h; the hollow glass microbeads are placed in a desiccator for drying, and the drying temperature is set to 130℃, and the time is 4h;

[0074] (2) The poly(4-methyl-1-pentene) and the bamboo fiber are weighed according to the weight ratio and put into a high-speed mixer, and the rotation speed of the high-speed mixer is set to 400 rpm, and the high-speed stirring time is 5 min;

[0075] (3) The mixed material of step (2) is taken out and placed in a co-rotating twin-screw extruder, and the rotation speed of the extruder is set to 250 rpm, the extrusion temperature is set to 210℃, and the die temperature is set to 200℃, to obtain a blended granular material;

[0076] (4) The blended granular material obtained in step (3) is ground by a liquid nitrogen cryogenic grinding machine, and the blended powder with a mesh size of >40 is screened out by a screen;

[0077] (5) The hollow glass microbeads dried in step (1) are placed in a 90wt% ethanol aqueous solution, and the silane coupling agent KH550 is added, and the ultrasonic dispersion is carried out at 80℃ for 2h, and the dispersed hollow glass microbeads are filtered and dried for 120 min, and the temperature is set to 120℃;

[0078] (6) The blended powder obtained in step (4) and the hollow glass microbeads obtained in step (5) are placed in a reversing mixer, and the rotation speed is set to 20 rpm, and the mixing time is set to 15 min;

[0079] (7) The mixed material obtained in step (6) is placed in a mold, and a plate material is pressed in a mold pressing machine, and the mold pressing temperature is set to 220℃, and the mold pressing time is set to 80 min, to obtain a low-density high-strength thermal insulation board;

[0080] (8) The low-density high-strength thermal insulation board obtained in step (7) is punched into a standard sample bar for testing.

[0081] Comparative Example 1

[0082] A thermal insulation board consisting of the following components:

[0083] Poly(4-methyl-1-pentene) 72 kg;

[0084] Bamboo fiber 12 kg;

[0085] Silane coupling agent KH550 1 kg.

[0086] The poly(4-methyl-1-pentene) used in this comparative example was purchased from Mitsui Chemical, brand RT18, density 0.833 g / cm 3 ; the true density of the bamboo fiber was 0.679 g / cm 3 .

[0087] The method for preparing the thermal insulation board as described above, the steps are as follows:

[0088] (1) Put the bamboo fiber into the desiccant drying oven and dry, set the drying temperature to 80℃, and the time to 4h;

[0089] (2) According to the weight ratio, weigh the poly(4-methyl-1-pentene) and bamboo fiber, and put them into a high-speed mixer, set the speed of the high-speed mixer to 200 rpm, and high-speed stir for 5 min;

[0090] (3) Take out the mixed material of step (2) and place it in a co-rotating twin-screw extruder, set the speed of the extruder to 200 rpm, the extrusion temperature to 200℃, and the die temperature to 190℃, to obtain a blended granule;

[0091] (4) Put the blended granule obtained in step (3) into a liquid nitrogen cryogenic mill for cryogenic grinding, and screen the blended powder with a mesh size >40 mesh using a screen;

[0092] (5) Add the silane coupling agent KH550 to the blended powder obtained in step (4), and place it in a tumbling mixer, set the speed to 20 rpm, and the mixing time to 10 min;

[0093] (6) Put the mixed material obtained in step (5) into a mold, and press it into a board material in a molding machine, set the molding temperature to 220℃, and the molding time to 60 min, to obtain a thermal insulation board;

[0094] (7) Punch the thermal board obtained in step (6) into a standard sample bar for testing.

[0095] Comparative Example 2

[0096] A thermal insulation board consisting of the following components:

[0097] Poly(4-methyl-1-pentene) 66 kg;

[0098] Hollow glass microsphere 18kg;

[0099] Silane coupling agent KH560 1kg.

[0100] The poly(4-methyl-1-pentene) used in the present comparative example was purchased from Mitsui Chemical, with trade name RT18, density 0.833g / cm 3 ; Hollow glass microsphere was purchased from Maanshan Mining Institute New Material Technology Co., Ltd. of China Steel Group, with trade name GS40, true density 0.4g / cm 3 , compressive strength (80% retention) 28MPa.

[0101] The preparation method of the heat insulation plate as described above, the steps are as follows:

[0102] (1) Put the hollow glass microspheres into the desiccant drying oven and dry, dry at 120℃ for 6h;

[0103] (2) According to the weight ratio, the poly(4-methyl-1-pentene) was weighed and put into the high-speed mixer, the speed of the high-speed mixer was set to 300rpm, and the high-speed stirring was 10min;

[0104] (3) The material of step (2) was taken out and placed in a co-rotating twin screw extruder, the speed of the extruder was set to 250rpm, the extrusion temperature was set to 200℃, and the die temperature was set to 190℃, to obtain granules;

[0105] (4) The granules obtained in step (3) were put into a liquid nitrogen freezing mill for freezing and powdering, and the powder with a mesh size of >40 mesh was screened out with a screen;

[0106] (5) The dried hollow glass microspheres of step (1) were placed in 90wt% ethanol aqueous solution, and the weighed silane coupling agent KH560 was added, and ultrasonic dispersion was carried out at 90℃ for 2h, and the dispersed hollow glass microspheres were filtered and dried for 120min, with the temperature set to 120℃;

[0107] (6) The powder obtained in step (4) and the hollow glass microspheres obtained in step (5) were placed in a tumbling mixer, the speed was set to 15rpm, and the mixing time was set to 15min;

[0108] (7) The mixed material obtained in step (6) was placed in a mold, and a plate material was pressed in a mold pressing machine, the mold pressing temperature was set to 220℃, and the mold pressing time was set to 60min, to obtain a heat insulation plate;

[0109] (8) The heat insulation plate obtained in step (7) was punched into a standard sample bar for testing.

[0110] Comparative Example 3

[0111] A thermal insulation board is composed of the following components:

[0112] Poly(4-methyl-1-pentene) 52.7 kg.

[0113] The poly(4-methyl-1-pentene) used in the present comparative example was purchased from Mitsui Chemical, with the trade name of DX820, and the density of 0.832 g / cm 3 .

[0114] The preparation method of the thermal insulation board as described above, with the following steps:

[0115] (1) The poly(4-methyl-1-pentene) was weighed and put into a high-speed mixer, with the rotation speed of the high-speed mixer set to 400 rpm, and high-speed stirring for 5 min;

[0116] (2) The mixed material in step (1) was taken out and put into a co-rotating twin-screw extruder, with the rotation speed of the extruder set to 250 rpm, the extrusion temperature set to 210℃, and the die temperature set to 200℃, to obtain granules;

[0117] (3) The granules obtained in step (2) were put into a liquid nitrogen freezing mill for freezing and grinding, and the powder with a mesh size >40 mesh was screened out by a screen;

[0118] (4) The powder obtained in step (3) was put into a tumbling mixer, with the rotation speed set to 20 rpm, and the mixing time set to 15 min;

[0119] (5) The material obtained in step (4) was put into a mold and pressed into a board material in a mold pressing machine, with the mold pressing temperature set to 220℃ and the mold pressing time set to 80 min, to obtain a thermal insulation board;

[0120] (6) The thermal insulation board obtained in step (5) was punched into a standard sample bar for testing.

[0121] The test data of the standard sample bars of the thermal insulation boards prepared in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1.

[0122] Table 1 Summary of test data of standard sample bars of thermal insulation boards prepared in Examples 1-3 and Comparative Examples 1-3

[0123]

[0124] As can be seen from the data in Table 1, the addition of hollow glass microspheres and natural fibers can improve the high temperature resistance and hardness of TPX, and can also reduce the density and thermal conductivity of TPX; it can be concluded from Example 1 and Comparative Example 1 that the addition of hollow glass microspheres greatly reduces the density of TPX; it can be concluded from Example 2 and Comparative Example 2 that the presence of natural fibers protects the hollow glass microspheres, which can alleviate the problem of increased density of TPX caused by the extrusion and crushing of hollow glass microspheres; in addition, natural fibers can also enhance the notched impact strength of TPX, and alleviate the problem of brittleness of materials caused by hollow glass microspheres.

[0125] The hollow glass microspheres are selected to reduce the specific gravity and thermal conductivity of poly(4-methyl-1-pentene), improve the hardness and high temperature resistance of TPX, and reduce the breakage rate of hollow glass microspheres through natural fibers, so that the prepared heat insulation plate can be used at high temperature (≥ 150℃), and has the performance of recyclability, light weight, low thermal conductivity and low deformation.

[0126] The above description is not a limitation of the present application, and the present application is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary skilled in the art within the scope of the present application should also be within the protection scope of the present application.

Claims

1. A low-density, high-strength thermal insulation board, characterized in that, The components include the following mass percentages: Poly(4-methyl-1-pentene) 40%~80%; Hollow glass microspheres: 1%~40%; Natural fibers: 1%~40%; Coupling agent 0.1%~2%; Furthermore, the method for preparing the low-density, high-strength thermal insulation board includes the following steps: (1) Dry the natural fibers in a dehumidifying drying oven; dry the hollow glass microspheres in a dehumidifying drying oven; (2) Weigh out poly(4-methyl-1-pentene) and natural fiber according to the weight ratio, and put them into a high-speed mixer to mix evenly; (3) Take out the mixed material from step (2), place it in a co-rotating twin-screw extruder, extrude and granulate it to obtain blended granules; (4) The blended granules obtained in step (3) are subjected to cryogenic grinding in a liquid nitrogen cryogenic grinding mill, and the blended powder with a mesh size > 40 mesh is screened out. (5) Place the hollow glass microspheres dried in step (1) into an ethanol aqueous solution, add the weighed coupling agent, disperse by ultrasonication, filter the dispersed hollow glass microspheres and dry them. (6) Place the blended powder obtained in step (4) and the hollow glass microspheres obtained in step (5) into a rotary mixer and mix them evenly; (7) Place the mixture obtained in step (6) into a mold and press it into a sheet material in a molding press to obtain a low-density high-strength heat insulation board.

2. The low-density, high-strength thermal insulation board as described in claim 1, characterized in that, The compressive strength of the hollow glass microspheres is ≥20 MPa.

3. The low-density, high-strength thermal insulation board as described in claim 1, characterized in that, The natural fiber is selected from any one or two of bamboo fiber and corn stalk fiber.

4. A method for preparing a low-density, high-strength thermal insulation board as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Dry the natural fibers in a dehumidifying drying oven; dry the hollow glass microspheres in a dehumidifying drying oven; (2) Weigh out poly(4-methyl-1-pentene) and natural fiber according to the weight ratio, and put them into a high-speed mixer to mix evenly; (3) Take out the mixed material from step (2), place it in a co-rotating twin-screw extruder, extrude and granulate it to obtain blended granules; (4) The blended granules obtained in step (3) are subjected to cryogenic grinding in a liquid nitrogen cryogenic grinding mill, and the blended powder with a mesh size > 40 mesh is screened out. (5) Place the hollow glass microspheres dried in step (1) into an ethanol aqueous solution, add the weighed coupling agent, disperse by ultrasonication, filter the dispersed hollow glass microspheres and dry them. (6) Place the blended powder obtained in step (4) and the hollow glass microspheres obtained in step (5) into a rotary mixer and mix them evenly; (7) Place the mixture obtained in step (6) into a mold and press it into a sheet material in a molding press to obtain a low-density high-strength heat insulation board.

5. The method for preparing a low-density, high-strength thermal insulation board as described in claim 4, characterized in that, In step (1), the temperature of the natural fiber during drying is set to 60~120 ℃ and the time is 2~12 h; the temperature of the hollow glass microspheres during drying is set to 100~150 ℃ and the time is 2~12 h.

6. The method for preparing a low-density, high-strength thermal insulation board as described in claim 4, characterized in that, In step (2), the speed of the high-speed mixer is set to 100~600 rpm, and the high-speed mixing is carried out for 2~30 min.

7. The method for preparing a low-density, high-strength thermal insulation board as described in claim 4, characterized in that, In step (3), the extruder speed is set to 100~400 rpm, the extrusion temperature is set to 150~300 ℃, and the die temperature is set to 100~300 ℃.

8. The method for preparing a low-density, high-strength thermal insulation board as described in claim 4, characterized in that, In step (5), the ultrasonic dispersion conditions are 60~120 ℃ and dispersion time is 1~10 h; the drying temperature is set to 80~150 ℃ and the duration is 30~240 min.

9. The method for preparing a low-density, high-strength thermal insulation board as described in claim 4, characterized in that, In step (6), the rotation speed of the rotary mixer is set to 10~60 rpm and the mixing time is set to 5~20 min.

10. The method for preparing a low-density, high-strength thermal insulation board as described in claim 4, characterized in that, In step (7), the molding temperature of the molding machine is set to 200~250 ℃ and the molding time is set to 20~180 min.

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