Composite thermal insulation material and preparation method thereof

Abstract

The present invention relates to the field of thermal insulation materials, and in particular to a composite thermal insulation material and a preparation method thereof. The composite thermal insulation material comprises, by weight, 55-75 parts of acrylonitrile-butadiene rubber, 20-40 parts of styrene-butadiene rubber, 16-32 parts of polyvinyl chloride, 5-10 parts of ethylene-vinyl acetate copolymer, 13-26 parts of modified filler, 6-12 parts of flame retardant, 1-3 parts of lubricant, 2.1-3.5 parts of vulcanizing agent, 1.5-3 parts of foaming agent and 0.6-1.2 parts of antioxidant. The composite thermal insulation material prepared by the present invention has not only excellent thermal insulation properties, but also has better strength, aging resistance and corrosion resistance than ordinary rubber and plastic materials.

Description

Technical Field

[0001] The present invention relates to the field of thermal insulation materials, and in particular to a composite thermal insulation material and a preparation method thereof. Background Art

[0002] Insulation of hot water pipes is crucial in the construction and maintenance of swimming pools. This not only affects the stability and comfort of pool water temperature but also impacts energy consumption and environmental protection. Pool hot water pipes primarily circulate heated water within the pool to maintain water temperature. Therefore, while handling high-temperature water, the pipes must also possess corrosion resistance, pressure resistance, and excellent sealing properties. In recent years, rubber-plastic insulated pipes have gained widespread application in various fields as a highly effective and environmentally friendly insulation material. Made primarily of rubber and plastic, these insulated pipes offer low thermal conductivity and excellent fire resistance, effectively reducing heat loss, maintaining stable water temperature, and enhancing safety. Furthermore, given the typically humid environment of swimming pools, rubber-plastic insulated pipes effectively prevent moisture penetration, maintaining internal dryness. The applicable temperature range for these pipes is generally between -50°C and +110°C. The typical temperature of a swimming pool's hot water system is typically below 40°C to 80°C. Therefore, from a technical perspective, the use of rubber-plastic insulated pipes is suitable for use in swimming pool hot water pipes. Within this range, the rubber-plastic insulated pipe can maintain its stable physical and chemical properties, provide excellent insulation effect and improve energy utilization efficiency.

[0003] While rubber-plastic insulated pipes offer significant advantages and are highly valuable for insulating swimming pool hot water pipes, in actual use, due to the complex composition of swimming pool water, which is generally alkaline and contains a large amount of chloride ions, long-term corrosion of rubber-plastic insulated pipes can significantly affect their insulation effectiveness and safety. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a composite thermal insulation material and a preparation method thereof.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides a composite thermal insulation material, calculated by weight, comprising:

[0007] 55-75 parts of nitrile rubber, 20-40 parts of styrene-butadiene rubber, 16-32 parts of polyvinyl chloride, 5-10 parts of ethylene-vinyl acetate copolymer, 13-26 parts of modified filler, 6-12 parts of flame retardant, 1-3 parts of lubricant, 2.1-3.5 parts of vulcanizing agent, 1.5-3 parts of foaming agent and 0.6-1.2 parts of antioxidant.

[0008] Preferably, the type of the nitrile rubber is one of NBR2707, NBR2870 and NBR3345.

[0009] Preferably, the type of the styrene-butadiene rubber is one of SBR1500E, SBR1502 and SBR1712.

[0010] Preferably, the parameters of the ethylene-vinyl acetate copolymer (EVA) are: vinyl acetate (VA) content of 18 wt % and melt index of 8 g / 10 min (190° C. / 2.16 kg).

[0011] Preferably, the melt index of the polyvinyl chloride is 13-18 g / 10 min (190°C / 2.16 kg), and the density is 1.36-1.39 g / cm 3 .

[0012] Preferably, the flame retardant is an inorganic silicon-based flame retardant, including any one of aluminum silicate, calcium silicate, and potassium aluminum silicate.

[0013] Preferably, the lubricant is any one of magnesium stearate, zinc stearate, and sodium stearate.

[0014] Preferably, the vulcanizing agent is a mixture of sulfur and zinc dimethacrylate in a mass ratio of 3-6:1.

[0015] Preferably, the foaming agent is any one of foaming agent AC, foaming agent H, and foaming agent OBSH.

[0016] Preferably, the antioxidant is any one of antioxidant 264, antioxidant 4010, antioxidant 3100, and antioxidant 4020.

[0017] Preferably, the preparation method of the modified filler comprises:

[0018] S1. Mix γ-aminopropyltriethoxysilane and ethanol solution, heat and reflux for 2-4 hours, then add allophane powder, continue to reflux for 6-10 hours, filter, wash and dry to obtain aminosilane-modified allophane;

[0019] S2. Dissolve allyl glycidyl ether in anhydrous ethanol, heat and reflux for 0.3-0.8 h, then add aminosilane-modified allophane, continue to reflux and stir for 2-6 h, filter, wash and dry to obtain allyl-modified allophane;

[0020] S3. Add allyl-modified allophane, 2-mercaptobenzimidazole and initiator into tetrahydrofuran, place under ultraviolet light and continue stirring for 1-3 hours, then filter, wash and dry to obtain a modified filler.

[0021] Preferably, in said S1, the mass fraction of the ethanol solution is 70%-90%; the particle size of the allophane powder is 7.2-8.6 μm, and the specific surface area is 55-65 m 2 / g, the SiO2 content is greater than 32%, and the Al2O3 content is greater than 50%.

[0022] Preferably, in S1, the mass volume ratio of γ-aminopropyltriethoxysilane, allophane powder and ethanol solution is (0.12-0.36) g: (1-2) g: (20-30) mL.

[0023] Preferably, in S2, the mass volume ratio of allyl alcohol glycidyl ether, aminosilane-modified allophane and anhydrous ethanol is (0.47-0.94) g: (1-1.5) g: (40-60) mL.

[0024] Preferably, in S3, the mass volume ratio of allyl-modified allophane, 2-mercaptobenzimidazole and tetrahydrofuran is (1-1.5) g: (0.52-0.86) g: (40-60) mL.

[0025] Preferably, in said S3, the initiator is dimethyl benzoate (DMPA), and the added amount is 4.5%-7.5% of 2-mercaptobenzimidazole.

[0026] In a second aspect, the present invention provides a method for preparing a composite thermal insulation material, comprising the following steps:

[0027] (1) Weighing nitrile rubber, styrene-butadiene rubber, polyvinyl chloride, and ethylene-vinyl acetate copolymer, mixing them in an internal mixer, heating them to 120-130° C., and mixing them for 10-20 minutes to obtain a first mixture;

[0028] (2) Weighing a modified filler, a flame retardant, a lubricant, and an antioxidant, adding them to the first mixture, and mixing them at 120-130° C. for 10-20 minutes to obtain a second mixture;

[0029] (3) Add the vulcanizing agent and the foaming agent to the second mixture, place it in a mold for vulcanization and foaming treatment, the treatment temperature is 135-165 ° C, the pressure is 6-10 MPa, the treatment time is 0.5-1 h, and after demolding and cooling, the desired product is obtained.

[0030] The beneficial effects of the present invention are:

[0031] The composite thermal insulation material disclosed herein is a rubber-plastic composite material, made from nitrile rubber and styrene-butadiene rubber (SBR) as the rubber raw materials and polyvinyl chloride (PVC) as the plastic raw material. Modified fillers, plasticizers, flame retardants, and other additives are added to improve the performance of the rubber-plastic composite material. The resulting composite thermal insulation material not only exhibits excellent thermal insulation properties but also possesses superior strength, aging resistance, and corrosion resistance compared to conventional rubber-plastic materials.

[0032] 2. The present invention's improvement to rubber and plastic materials primarily involves the use of modified allophane as a filler. Allophane is an aluminosilicate mineral with a large specific surface area, good strength and high-temperature resistance, and excellent adsorption properties. The present invention incorporates a series of modifications to make it suitable for use as a thermal insulation filler in rubber and plastic.

[0033] 3. The modification process of allophane according to the present invention includes: firstly carrying out aminosilane modification to graft a large number of amino groups on its surface; then using the epoxy group in allyl glycidyl ether to combine with the amino group in the aminosilane-modified allophane to obtain allyl-modified allophane; finally, a mercapto-ene click reaction occurs between the mercapto group in 2-mercaptobenzimidazole and the double bond in the allyl-modified allophane to finally prepare a modified filler.

[0034] 4. Compared with ordinary allophane, the modified allophane of the present invention has better compatibility with rubber and plastic materials. Testing of the prepared composite materials found that the performance improvement of the modified allophane on rubber and plastic materials is mainly reflected in strength, aging resistance and corrosion resistance. In addition, it can also ensure good flame retardancy and thermal insulation, thereby ensuring excellent thermal insulation effect and safety performance during use. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the presence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be regarded as the scope of the present invention.

[0036] In order to better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0037] The particle size of the allophane powder used in the embodiment of the present invention is 7.2-8.6 μm, and the specific surface area is 55-65 m 2 / g, the SiO2 content is greater than 32%, and the Al2O3 content is greater than 50%.

[0038] The present invention will be further described below with reference to the following examples.

[0039] Example 1

[0040] A composite thermal insulation material, calculated by weight, comprising:

[0041] 65 parts of nitrile rubber, 30 parts of styrene-butadiene rubber, 24 parts of polyvinyl chloride, 8 parts of ethylene-vinyl acetate copolymer, 18 parts of modified filler, 10 parts of flame retardant, 2 parts of lubricant, 2.8 parts of vulcanizing agent, 2.2 parts of foaming agent and 0.9 part of antioxidant.

[0042] The model of nitrile rubber is NBR2707; the model of styrene-butadiene rubber is SBR1500E; the parameters of ethylene-vinyl acetate copolymer (EVA) are: vinyl acetate (VA) content is 18wt%, melt index is 8g / 10min (190℃ / 2.16kg); the melt index of polyvinyl chloride is 15g / 10min (190℃ / 2.16kg), and the density is 1.37g / cm 3 The flame retardant is aluminum silicate; the lubricant is magnesium stearate; the vulcanizing agent is a mixture of sulfur and zinc dimethacrylate in a mass ratio of 4:1; the foaming agent is foaming agent AC; and the antioxidant is antioxidant 264.

[0043] The preparation method of the modified filler comprises:

[0044] S1. Mix γ-aminopropyltriethoxysilane and a 70%-90% ethanol solution by mass, heat to 70-80°C and reflux for 2-4 hours, then add allophane powder, the mass volume ratio of γ-aminopropyltriethoxysilane, allophane powder and ethanol solution is 0.24g:1.5g:25mL, continue to reflux for 8 hours, filter to obtain a residue, wash with pure water at least once, and vacuum dry to obtain aminosilane-modified allophane;

[0045] S2. Dissolve allyl alcohol glycidyl ether in anhydrous ethanol, heat to 75° C. and reflux for 0.5 h, then add aminosilane-modified allophane, the mass volume ratio of allyl alcohol glycidyl ether, aminosilane-modified allophane and anhydrous ethanol is 0.71 g:1.2 g:50 mL, continue to reflux and stir for 4 h, filter to obtain a residue, wash with ethanol at least once, and vacuum dry to obtain allyl-modified allophane;

[0046] S3. Add allyl-modified allophane and 2-mercaptobenzimidazole to tetrahydrofuran, the mass volume ratio of allyl-modified allophane, 2-mercaptobenzimidazole and tetrahydrofuran is 1.2g:0.69g:50mL, and then add photoinitiator dimethyl benzoate (DMPA) in an amount of 6% of 2-mercaptobenzimidazole. Place under ultraviolet lamp and stir continuously for 2h at a stirring speed of 200r / min. Then filter to obtain a residue, wash with ethanol at least once, and vacuum dry to obtain a modified filler.

[0047] The preparation method of the composite thermal insulation material comprises the following steps:

[0048] (1) Weighing nitrile rubber, styrene-butadiene rubber, polyvinyl chloride, and ethylene-vinyl acetate copolymer, mixing them in an internal mixer, heating to 125° C., and mixing for 15 minutes to obtain a first mixture;

[0049] (2) Weighing a modified filler, a flame retardant, a lubricant, and an antioxidant, adding them to the first mixture, and mixing at 125° C. for 15 minutes to obtain a second mixture;

[0050] (3) Add the vulcanizing agent and the foaming agent to the second mixture, place it in a mold for vulcanization and foaming treatment, the treatment temperature is 150°C, the pressure is 8MPa, and the treatment time is 0.6h. After demolding and cooling, the desired product is obtained.

[0051] Example 2

[0052] A composite thermal insulation material, calculated by weight, comprising:

[0053] 55 parts of nitrile rubber, 40 parts of styrene-butadiene rubber, 16 parts of polyvinyl chloride, 10 parts of ethylene-vinyl acetate copolymer, 13 parts of modified filler, 12 parts of flame retardant, 1 part of lubricant, 3.5 parts of vulcanizing agent, 1.5 parts of foaming agent and 1.2 parts of antioxidant.

[0054] The model of nitrile rubber is NBR2870; the model of styrene-butadiene rubber is SBR1502; the parameters of ethylene-vinyl acetate copolymer (EVA) are: vinyl acetate (VA) content is 18wt%, melt index is 8g / 10min (190℃ / 2.16kg); the melt index of polyvinyl chloride is 15g / 10min (190℃ / 2.16kg), and the density is 1.37g / cm 3 The flame retardant is calcium silicate; the lubricant is zinc stearate; the vulcanizing agent is a mixture of sulfur and zinc dimethacrylate in a mass ratio of 3:1; the foaming agent is foaming agent H; and the antioxidant is antioxidant 4010.

[0055] The preparation method of the modified filler comprises:

[0056] S1. Mix γ-aminopropyltriethoxysilane and a 70% by mass ethanol solution, heat to 70°C and reflux for 2 h, then add allophane powder, the mass volume ratio of γ-aminopropyltriethoxysilane, allophane powder and ethanol solution is 0.12 g:1 g:20 mL, continue to reflux for 6 h, filter to obtain a residue, wash with pure water at least once, and vacuum dry to obtain aminosilane-modified allophane;

[0057] S2. Dissolve allyl alcohol glycidyl ether in anhydrous ethanol, heat to 70° C. and reflux for 0.3 h, then add aminosilane-modified allophane, the mass volume ratio of allyl alcohol glycidyl ether, aminosilane-modified allophane and anhydrous ethanol is 0.47 g:1 g:40 mL, continue to reflux and stir for 2 h, filter to obtain a residue, wash with ethanol at least once, and vacuum dry to obtain allyl-modified allophane;

[0058] S3. Add allyl-modified allophane and 2-mercaptobenzimidazole to tetrahydrofuran, the mass volume ratio of allyl-modified allophane, 2-mercaptobenzimidazole and tetrahydrofuran is 1g:0.52g:40mL, and then add photoinitiator benzoin dimethyl ether (DMPA) in an amount of 4.5% of 2-mercaptobenzimidazole. Place under ultraviolet lamp and stir continuously for 1h at a stirring speed of 100r / min. Then filter to obtain a residue, wash with ethanol at least once, and vacuum dry to obtain a modified filler.

[0059] The preparation method of the composite thermal insulation material comprises the following steps:

[0060] (1) Weighing nitrile rubber, styrene-butadiene rubber, polyvinyl chloride, and ethylene-vinyl acetate copolymer, mixing them in an internal mixer, heating them to 120° C., and mixing them for 10 minutes to obtain a first mixture;

[0061] (2) Weighing a modified filler, a flame retardant, a lubricant, and an antioxidant, adding them to the first mixture, and mixing at 120° C. for 10 minutes to obtain a second mixture;

[0062] (3) Add the vulcanizing agent and the foaming agent to the second mixture, place it in a mold for vulcanization and foaming treatment, the treatment temperature is 135 ° C, the pressure is 6 MPa, the treatment time is 0.5 h, and after demolding and cooling, the desired product is obtained.

[0063] Example 3

[0064] A composite thermal insulation material, calculated by weight, comprising:

[0065] 75 parts of nitrile rubber, 40 parts of styrene-butadiene rubber, 32 parts of polyvinyl chloride, 10 parts of ethylene-vinyl acetate copolymer, 26 parts of modified filler, 12 parts of flame retardant, 3 parts of lubricant, 3.5 parts of vulcanizing agent, 3 parts of foaming agent and 1.2 parts of antioxidant.

[0066] The model of nitrile rubber is NBR3345; the model of styrene-butadiene rubber is SBR1712; the parameters of ethylene-vinyl acetate copolymer (EVA) are: vinyl acetate (VA) content is 18wt%, melt index is 8g / 10min (190℃ / 2.16kg); the melt index of polyvinyl chloride is 15g / 10min (190℃ / 2.16kg), and the density is 1.37g / cm 3 The flame retardant is potassium aluminum silicate; the lubricant is sodium stearate; the vulcanizing agent is a mixture of sulfur and zinc dimethacrylate in a mass ratio of 6:1; the foaming agent is foaming agent OBSH; and the antioxidant is antioxidant 3100.

[0067] The preparation method of the modified filler comprises:

[0068] S1. Mix γ-aminopropyltriethoxysilane and a 90% by mass ethanol solution, heat to 80°C and reflux for 4 h, then add allophane powder, the mass volume ratio of γ-aminopropyltriethoxysilane, allophane powder and ethanol solution is 0.36 g:2 g:30 mL, continue to reflux for 10 h, filter to obtain a residue, wash with pure water at least once, and vacuum dry to obtain aminosilane-modified allophane;

[0069] S2. Dissolve allyl alcohol glycidyl ether in anhydrous ethanol, heat to 80° C. and reflux for 0.8 h, then add aminosilane-modified allophane, the mass volume ratio of allyl alcohol glycidyl ether, aminosilane-modified allophane and anhydrous ethanol is 0.94 g:1.5 g:60 mL, continue to reflux and stir for 6 h, filter to obtain a residue, wash with ethanol at least once, and vacuum dry to obtain allyl-modified allophane;

[0070] S3. Add allyl-modified allophane and 2-mercaptobenzimidazole to tetrahydrofuran, the mass volume ratio of allyl-modified allophane, 2-mercaptobenzimidazole and tetrahydrofuran is 1.5g:0.86g:60mL, and then add photoinitiator benzoin dimethyl ether (DMPA) in an amount of 7.5% of 2-mercaptobenzimidazole. Place under ultraviolet lamp and stir continuously for 3h at a stirring speed of 300r / min. Then filter to obtain a residue, wash with ethanol at least once, and vacuum dry to obtain a modified filler.

[0071] The preparation method of the composite thermal insulation material comprises the following steps:

[0072] (1) Weighing nitrile rubber, styrene-butadiene rubber, polyvinyl chloride, and ethylene-vinyl acetate copolymer, mixing them in an internal mixer, heating them to 130° C., and mixing them for 20 minutes to obtain a first mixture;

[0073] (2) Weighing a modified filler, a flame retardant, a lubricant, and an antioxidant, adding them to the first mixture, and mixing at 130° C. for 20 minutes to obtain a second mixture;

[0074] (3) Add the vulcanizing agent and the foaming agent to the second mixture, place it in a mold for vulcanization and foaming treatment, the treatment temperature is 165 ° C, the pressure is 10 MPa, the treatment time is 1 hour, and after demolding and cooling, the desired product is obtained.

[0075] Comparative Example 1

[0076] A composite thermal insulation material differs from Example 1 only in that the modified filler is replaced by allophane.

[0077] Comparative Example 2

[0078] A composite thermal insulation material, which differs from Example 1 only in that the modified filler is replaced by allyl-modified hydrophobic stone (prepared in the same manner as Example 1).

[0079] Comparative Example 3

[0080] A composite thermal insulation material differs from Example 1 only in that the modified filler is replaced by a mixture of allophane and 2-mercaptobenzimidazole, and the mass ratio of allophane to 2-mercaptobenzimidazole is 1.2:0.69.

[0081] Experimental testing

[0082] The properties of the composite thermal insulation materials prepared in Example 1 and Comparative Examples 1-3 were tested. The tensile strength was determined according to GB / T 528-2009, the thermal conductivity was determined according to GB / T 11205-2009, and the oxygen index was determined according to ASTM D2863. The aging resistance test was performed under a light intensity of 550 W / m 2The steel was irradiated under a xenon lamp for 300 hours to observe whether the surface was cracked. The corrosion resistance test was: soaked in a 10wt% sodium chloride solution at 60°C for 168 hours, then the tensile strength was tested and the rate of change was calculated.

[0083] The data detection results are shown in Table 1:

[0084] Table 1 Performance results of different materials

[0085]

[0086] It can be seen from the test results in Table 1 that the strength, aging resistance and salt corrosion resistance of the composite thermal insulation material prepared in Example 1 are significantly improved. In addition, the thermal conductivity and flame retardancy are also slightly improved, indicating that it has good thermal insulation effect and safety performance when used.

[0087] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0088] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A composite thermal insulation material, characterized in that: Calculated in parts by weight, including: 55-75 parts of nitrile rubber, 20-40 parts of styrene-butadiene rubber, 16-32 parts of polyvinyl chloride, 5-10 parts of ethylene-vinyl acetate copolymer, 13-26 parts of modified filler, 6-12 parts of flame retardant, 1-3 parts of lubricant, 2.1-3.5 parts of vulcanizing agent, 1.5-3 parts of foaming agent and 0.6-1.2 parts of antioxidant; The modified filler is prepared by sequentially subjecting allophane to aminosilane modification and allyl modification, and then compounding with 2-mercaptobenzimidazole.

2. A composite thermal insulation material according to claim 1, characterized in that: The model of the nitrile rubber is one of NBR2707, NBR2870, and NBR3345; the model of the styrene butadiene rubber is one of SBR1500E, SBR1502, and SBR1712.

3. The composite thermal insulation material according to claim 1, characterized in that: The parameters of the ethylene-vinyl acetate copolymer (EVA) are: vinyl acetate (VA) content of 18 wt%, melt index of 8 g / 10 min at 190°C and 2.16 kg; the melt index of the polyvinyl chloride is 13-18 g / 10 min at 190°C and 2.16 kg, and the density is 1.36-1.39 g / cm 3 .

4. The composite thermal insulation material according to claim 1, characterized in that: The flame retardant is an inorganic silicon flame retardant, including any one of aluminum silicate, calcium silicate, and potassium aluminum silicate; the lubricant is any one of magnesium stearate, zinc stearate, and sodium stearate; and the vulcanizing agent is a mixture of sulfur and zinc dimethacrylate in a mass ratio of 3-6:

1.

5. The composite thermal insulation material according to claim 1, characterized in that: The foaming agent is any one of foaming agent AC, foaming agent H, and foaming agent OBSH; the antioxidant is any one of antioxidant 264, antioxidant 4010, antioxidant 3100, and antioxidant 4020.

6. The composite thermal insulation material according to claim 1, characterized in that: The preparation method of the modified filler comprises: S1. Mix γ-aminopropyltriethoxysilane and ethanol solution, heat and reflux for 2-4 hours, then add allophane powder, continue to reflux for 6-10 hours, filter, wash and dry to obtain aminosilane-modified allophane; S2. Dissolve allyl glycidyl ether in anhydrous ethanol, heat and reflux for 0.3-0.8 h, then add aminosilane-modified allophane, continue to reflux and stir for 2-6 h, filter, wash and dry to obtain allyl-modified allophane; S3. Add allyl-modified allophane, 2-mercaptobenzimidazole and initiator into tetrahydrofuran, place under ultraviolet light and continue stirring for 1-3 hours, then filter, wash and dry to obtain a modified filler.

7. The composite thermal insulation material according to claim 6, characterized in that: In the S1, the mass volume ratio of γ-aminopropyltriethoxysilane, allophane powder and ethanol solution is (0.12-0.36) g: (1-2) g: (20-30) mL.

8. The composite thermal insulation material according to claim 6, characterized in that: In the S2, the mass volume ratio of allyl alcohol glycidyl ether, aminosilane-modified allophane and anhydrous ethanol is (0.47-0.94) g: (1-1.5) g: (40-60) mL.

9. The composite thermal insulation material according to claim 6, characterized in that: In S3, the mass volume ratio of allyl-modified allophane, 2-mercaptobenzimidazole and tetrahydrofuran is (1-1.5) g: (0.52-0.86) g: (40-60) mL; the initiator is dimethyl benzoate (DMPA), and the added amount is 4.5%-7.5% of 2-mercaptobenzimidazole.

10. A method for preparing the composite thermal insulation material according to claim 1, characterized in that: The following steps are involved: (1) Weighing nitrile rubber, styrene-butadiene rubber, polyvinyl chloride, and ethylene-vinyl acetate copolymer, mixing them in an internal mixer, heating them to 120-130° C., and mixing them for 10-20 minutes to obtain a first mixture; (2) Weighing the modified filler, flame retardant, lubricant and antioxidant, adding them to the first mixture, and mixing them at 120-130°C for 10-20 minutes to obtain a second mixture; (3) Add the vulcanizing agent and the foaming agent to the second mixture, place it in a mold for vulcanization and foaming treatment, the treatment temperature is 135-165 ° C, the pressure is 6-10 MPa, the treatment time is 0.5-1h, and after demolding and cooling, the desired product is obtained.

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