Straw aerogel composite insulation board and preparation method thereof

Abstract

The invention belongs to the technical field of thermal insulation materials, and particularly relates to a straw aerogel composite thermal insulation board and a preparation method thereof, the composite thermal insulation board is prepared from the following raw materials: 80-100 parts of a straw modifier, 65-85 parts of an aerogel compound, 15-35 parts of an antioxidant hydrophobic substance, 30-45 parts of phenolic resin and 30 parts of a silane coupling agent; the straw modifier and the aerogel compound are used as main materials, the straw modifier and the phenolic resin are combined through hydrogen bonds by virtue of hydroxyl functional groups to realize mutual support, and the aerogel compound and the phenolic resin synergistically enhance the thermal insulation performance and keep stable by virtue of physical combination; the straw modifier and the aerogel compound also form a toughening-reinforcing complementary structure; the silane coupling agent improves the compatibility between the materials and partially enhances the crosslinking effect of the phenolic resin, the anti-oxidation hydrophobic substance is sprayed on the surface to improve the surface property of the insulation board, and the strength, the heat preservation property and the hydrophobicity of the prepared insulation board are remarkably improved compared with those of an existing insulation material.

Description

Technical Field

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

[0002] With the continuous development of the construction industry and industrial insulation field, the performance requirements for insulation boards are increasing.

[0003] Among the existing insulation boards, some organic insulation boards have certain insulation properties, but they often have problems such as insufficient strength, easy aging, poor insulation performance and poor water resistance, which makes them unreliable during long-term use and poses safety hazards. At the same time, their insulation effect will be greatly reduced when they are in a humid environment for a long time; and inorganic insulation boards, although they have good fire resistance and water resistance, are usually brittle and have poor toughness. They are prone to damage during installation and use, resulting in a decrease in insulation performance; traditional insulation boards have gradually exposed many limitations in actual applications and are difficult to meet diverse usage needs.

[0004] In view of the various shortcomings of the above existing insulation boards, there is an urgent need to develop a new insulation board that can comprehensively overcome these defects and has good strength, excellent thermal insulation performance and outstanding hydrophobicity. Summary of the Invention

[0005] In order to overcome the defects of the existing technology, the straw aerogel composite insulation board proposed in the present invention uses straw modifications and aerogel composites as the main materials. The straw modifications achieve mutual support with the phenolic resin through hydrogen bonding by virtue of the hydroxyl functional groups. The former provides physical support for the latter and makes the pore filling more dense. The aerogel composite and the phenolic resin synergistically enhance the thermal insulation performance and maintain stability by physical bonding. The straw modifications also form a toughening-reinforcement complementary structure with the aerogel composite; the silane coupling agent improves the compatibility between materials and partially enhances the cross-linking effect of the phenolic resin. The surface is sprayed with an antioxidant hydrophobic agent, and the temperature resistance is improved by aluminum oxide, and the hydrophobicity is ensured by plant wax. The insulation board has significantly improved performance in strength, thermal insulation and hydrophobicity compared with existing insulation materials.

[0006] To achieve the above-mentioned object, the technical solution adopted by the present invention is a straw aerogel composite insulation board, which is prepared from the following raw materials in parts by weight: 80-100 parts of straw modification, 65-85 parts of aerogel composite, 15-35 parts of antioxidant hydrophobic material, 30-45 parts of phenolic resin, and 30 parts of silane coupling agent; Furthermore, the preparation method of the antioxidant hydrophobe comprises the following steps: (a) weighing natural rubber and adding it to a mixed solution of tetrahydrofuran and toluene, wherein the mass ratio of natural rubber to the mixed solution is 2-4:25, and the volume percentages of tetrahydrofuran and toluene in the mixed solution are 20%:80%, heating the mixture to 50°C and stirring at 500 r / min for 30 minutes to obtain a homogenized rubber solution; (β) Weighing 4-6 parts of aluminum oxide, drying them at 65° C. for 2 hours, and grinding them to obtain aluminum oxide powder, adding the aluminum oxide powder to the homogenizing solution obtained in step (α), and stirring at a speed of 500 r / min for 30 minutes to obtain an antioxidant homogenizing solution; (γ) Weighing 5 parts of vegetable wax and adding it to the antioxidant homogeneous glue solution obtained in step (β), heating it to 90-110° C. using a cooling reflux device, stirring it at a speed of 500 r / min for 60 minutes, and sealing it for 5 hours to obtain an antioxidant hydrophobic substance.

[0007] Furthermore, the method for preparing the aerogel composite comprises the following steps: (I) Weighing 3.5-5.5 parts of graphene powder and 4.5 parts of nano-silicon dioxide into 15 parts of anhydrous ethanol, stirring at a speed of 300 r / min for 30 minutes to obtain a carbon-silicon mixed dispersion; (II) Weighing 6-9 parts of methyltrimethoxysilane, adding it to the carbon-silicon mixed dispersion obtained in step (I), adding 1-3 parts of acid solution, stirring at a speed of 500 r / min for 40 minutes, sealing and standing at 25°C for 24 hours to obtain an aerogel composite.

[0008] Graphene powder and nano-silica are physically adsorbed through van der Waals forces, and the two structurally cooperate with each other. Graphene provides a supporting framework for nano-silica, which is conducive to the construction of a stable three-dimensional network structure; nano-silica and methyltrimethoxysilane undergo hydrolysis and condensation under acid catalysis to form Si-O-Si bonds, thereby modifying the surface of nano-silica; these interactions jointly promote the formation and performance construction of aerogel composites.

[0009] Furthermore, the method for preparing the modified straw comprises the following steps: (a) Weighing 15-20 parts of straw, drying them at 80°C for 6 hours, crushing them, and sieving them through a 20-mesh screen to obtain straw powder. The obtained straw powder was added to 50 parts of deionized water, and the pH was adjusted to neutral by adding salt solution. The powder was washed with deionized water five times and dried at 80°C for 12 hours to obtain alkalized straw powder. Weighing 8-12 parts of clay, drying them at 110°C for 12 hours, grinding them, and sieving them through an 80-mesh screen to obtain clay fine powder. (b) Weigh 10-12 parts of epoxy resin, heat to 80°C, and stir at 500 r / min for 30 minutes, add 3 parts of rosin, heat to 120°C, and stir at 500 r / min for 20 minutes to obtain a mixed solution I; (c) adding 9-15 parts of graphite powder to the mixed solution I obtained in step (b), ultrasonically treating the mixture at a power of 0.5 kW for 30 minutes, heating the mixture to 110° C., and stirring the mixture at a speed of 500 rpm for 30 minutes to obtain a substrate mixture; (d) adding the alkalized straw powder obtained in step (a) to the base mixture, heating to 90° C., and stirring at a rotation speed of 500 r / min for 30 min to obtain a straw modified material precursor; (e) adding the clay powder obtained in step (a) to the straw modified product precursor obtained in step (d), heating the mixture to 60° C., stirring the mixture at a rotation speed of 500 r / min for 2 h, and introducing a gas at a flow rate of 120 ml / min, wherein the gas is either argon or nitrogen, to obtain a straw modified product.

[0010] Filling the pores of straw with clay prevents the pores from affecting the strength and improves the overall thermal insulation performance. Straw contains rich hydroxyl functional groups, which can form hydrogen bonds with the hydroxyl groups of epoxy resin molecules. The hydrogen bonding effect helps the resin molecules adhere to the surface of the straw, thereby achieving straw modification.

[0011] The present invention also provides a method for preparing a straw aerogel composite insulation board, comprising the following steps: Step 1: Weigh 80-100 parts of the modified straw and 65-85 parts of the aerogel composite, add them to 30 parts of a silane coupling agent, and stir at a speed of 1500 r / min for 1 hour to obtain a mixture I; Step 2: Add 55-80 parts of phenolic resin to the mixture I obtained in step 1, and stir at a speed of 1500 r / min for 30 minutes to obtain a paste; Step 3: Pour the paste obtained in step 2 into a mold, and cure it at room temperature of 25°C under a cold pressing pressure of 10 MPa for 1 hour to obtain a solidified product; Step 4: Weigh 15-35 parts of antioxidant hydrophobic material and spray it evenly onto the surface of the solidified material. Then, perform secondary cold pressing and solidification at room temperature of 25°C and a cold pressing pressure of 15 MPa for 2 hours to obtain a straw aerogel composite insulation board blank. Step 5: Place the straw aerogel composite insulation board blank obtained in step 4 in a ventilated environment for cross-linking for 72 hours, and place it in an oven at a temperature of 110-150° C. for 8 hours to obtain a straw aerogel composite insulation board.

[0012] Straw modifications and aerogel composites were selected as the main materials. The straw modifications and phenolic resins were initially combined and supported each other through hydrogen bonding. The former provided physical support for the latter, and the latter filled the pores of the former to make it denser. The aerogel composite and phenolic resin synergistically enhanced the thermal insulation performance and maintained stability through physical bonding. The straw modifications served as toughening insulation materials and complemented the structures of the aerogel composite reinforced insulation materials. The silane coupling agent played an interfacial modification role, improving the compatibility between the straw modifications, aerogel composites and phenolic resins, and at the same time partially enhancing the cross-linking effect of the phenolic resin. In order to improve the antioxidant and waterproof properties of the straw aerogel composite insulation board, antioxidant hydrophobic material was sprayed on the surface. The presence of aluminum oxide improved the temperature resistance of the surface. At the same time, plant wax, as a natural hydrophobic material, ensured the hydrophobicity of the surface.

[0013] The straw aerogel composite insulation board prepared by the present invention has greatly improved performance in terms of strength, thermal insulation and hydrophobicity compared with the insulation materials in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram of the preparation method of the straw aerogel composite insulation board proposed in the present invention; Figure 2 This is a material distribution plan of the straw aerogel composite insulation board proposed in the present invention; Figure 3 Graph showing the strength test of the straw aerogel composite insulation board prepared in Examples and Comparative Examples; Figure 4 This is a test diagram of thermal conductivity of the straw aerogel composite insulation board prepared in the embodiment and comparative example; Figure 5 These are test graphs of the loss rate and hydrophobicity of the straw aerogel composite insulation boards prepared in the examples and comparative examples.

[0015] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods and materials similar or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0018] The preparation methods and material distribution in the following examples are referenced to Figure 1 and Figure 2 Unless otherwise specified, conventional methods are used. Materials used in the following examples are calculated by weight unless otherwise specified. All materials used are new materials purchased from the market, and saturated solutions are prepared according to the solubility of the materials at 25°C.

[0019] Example 1: A straw aerogel composite insulation board is prepared from the following raw materials in parts by weight: 80 parts of straw modification, 65 parts of aerogel composite, 15 parts of antioxidant hydrophobic material, 30 parts of phenolic resin, and 30 parts of KH550 (γ-aminopropyltriethoxysilane); The preparation method of the antioxidant hydrophobe comprises the following steps: (a) Weighing 2 parts of natural rubber and adding it to a mixed solution of 25 parts of tetrahydrofuran and toluene, wherein the volume percentages of tetrahydrofuran and toluene in the mixed solution are 20%:80%, heating the mixture to 50°C and stirring at 500 r / min for 30 minutes to obtain a homogenized rubber solution; (β) Weighing 4 parts of aluminum oxide, drying them at 65° C. for 2 hours, and grinding them to obtain aluminum oxide powder, adding the aluminum oxide powder to the homogenizing solution obtained in step (α), and stirring at a speed of 500 r / min for 30 minutes to obtain an antioxidant homogenizing solution; (γ) Weigh 5 parts of carnauba wax and add it to the antioxidant homogeneous glue solution obtained in step (β). Heat it to 90° C. using a cooling reflux device and stir it at a speed of 500 r / min for 60 min. Then seal and store it for 5 h to obtain an antioxidant hydrophobic substance.

[0020] The preparation method of the aerogel composite comprises the following steps: (I) Weighing 3.5 parts of graphene powder and 4.5 parts of nano-silicon dioxide into 15 parts of anhydrous ethanol, stirring at a speed of 300 r / min for 30 minutes to obtain a carbon-silicon mixed dispersion; (II) Weighing 6 parts of methyltrimethoxysilane, adding it to the carbon-silicon mixed dispersion obtained in step (I), adding 1 part of glacial acetic acid, stirring at a speed of 500 r / min for 40 minutes, sealing and standing at 25°C for 24 hours to obtain an aerogel composite.

[0021] The preparation method of the modified straw comprises the following steps: (a) Weigh 15 parts of corn straw, dry them at 80°C for 6 h, grind them, and sieve them through a 20-mesh screen to obtain straw powder. The obtained straw powder is added to 50 parts of deionized water, the pH is adjusted to neutral by adding saturated sodium carbonate solution, washed with deionized water five times, and dried at 80°C for 12 h to obtain alkalized straw powder. Weigh 8 parts of kaolin, dry them at 110°C for 12 h, grind them, and sieve them through an 80-mesh screen to obtain clay fine powder. (b) 10 parts of epoxy resin were weighed, heated to 80°C, and stirred at 500 r / min for 30 min. 3 parts of rosin were added, and the mixture was heated to 120°C and stirred at 500 r / min for 20 min to obtain a mixed solution I. (c) Weighing 9 parts of graphite powder, adding it to the mixed solution I obtained in step (b), ultrasonically treating it at a power of 0.5 kW for 30 minutes, heating it to 110° C., and stirring it at a speed of 500 rpm for 30 minutes to obtain a base mixture; (d) adding the alkalized straw powder obtained in step (a) to the base mixture, heating to 90° C., and stirring at a rotation speed of 500 r / min for 30 min to obtain a straw modified material precursor; (e) adding the clay powder obtained in step (a) to the straw modified product precursor obtained in step (d), heating the mixture to 60° C., stirring the mixture at a rotation speed of 500 r / min for 2 h, and introducing argon gas at a flow rate of 120 ml / min to obtain a straw modified product.

[0022] This embodiment also provides a method for preparing a straw aerogel composite insulation board, comprising the following steps: Step 1: Weigh 80 parts of the modified straw and 65 parts of the aerogel composite into 30 parts of KH550, and stir at a speed of 1500 r / min for 1 hour to obtain a mixture I; Step 2: Add 30 parts of phenolic resin to the mixture I obtained in step 1, and stir at a speed of 1500 r / min for 30 minutes to obtain a paste; Step 3: Pour the paste obtained in step 2 into a mold, and cure it at room temperature of 25°C under a cold pressing pressure of 10 MPa for 1 hour to obtain a solidified product; Step 4: Weigh 15 parts of antioxidant hydrophobic material and spray it evenly onto the surface of the solidified material. At room temperature of 25°C, perform secondary cold pressing and solidification at a cold pressing pressure of 15 MPa for 2 hours to obtain a straw aerogel composite insulation board blank. Step 5: Place the straw aerogel composite insulation board blank obtained in step 4 in a ventilated environment for cross-linking for 72 hours, and place it in an oven at a temperature of 110° C. for 8 hours to obtain a straw aerogel composite insulation board.

[0023] Embodiment 2: a straw aerogel composite thermal insulation board is prepared from the following raw materials by weight: 90 parts of straw modifier, 75 parts of aerogel composite, 25 parts of antioxidant hydrophobic material, 38 parts of phenolic resin, and 30 parts of KH550; The preparation method of the antioxidant hydrophobic material comprises the following steps: (α) 3 parts of natural rubber are weighed and added into a mixed solution of 25 parts of tetrahydrofuran and toluene, wherein the volume percentage of tetrahydrofuran and toluene in the mixed solution is 20:80%, the temperature is heated to 50°C, and stirring is performed at a speed of 500 r / min for 30 min to obtain a uniform glue solution; (β) 5 parts of alumina are weighed and dried at 65°C for 2 h, and then ground to obtain alumina powder particles, which are added into the uniform glue solution obtained in step (α) and stirred at a speed of 500 r / min for 30 min to obtain an antioxidant uniform glue solution; (γ) 5 parts of carnauba wax are weighed and added into the antioxidant uniform glue solution obtained in step (β), heated to 100°C by using a cooling reflux device, and stirred at a speed of 500 r / min for 60 min, and then sealed and stored to obtain an antioxidant hydrophobic material.

[0024] The preparation method of the aerogel composite comprises the following steps: (I) 4.5 parts of graphene powder and 4.5 parts of nano-silicon dioxide are weighed and added into 15 parts of anhydrous ethanol, and stirred at a speed of 300 r / min for 30 min to obtain a carbon-silicon mixed dispersion; (II) 7.5 parts of methyltrimethoxysilane are weighed and added into the carbon-silicon mixed dispersion obtained in step (I), 2 parts of glacial acetic acid are added, and stirring is performed at a speed of 500 r / min for 40 min, and then sealed and placed at 25°C for 24 h to obtain an aerogel composite.

[0025] The preparation method of the straw modifier comprises the following steps: (a) 18 parts of corn straw are weighed and dried at 80°C for 6 h, crushed, and sieved by using a 20-mesh screen to obtain straw powder particles, which are added into 50 parts of deionized water, a saturated sodium carbonate solution is added to adjust the pH to neutral, the deionized water is washed for 5 times, and then dried at 80°C for 12 h to obtain alkalized straw powder particles, 10 parts of kaolin are weighed and dried at 110°C for 12 h, ground, and sieved by using an 80-mesh screen to obtain clay powder; (b) 11 parts of epoxy resin are weighed, heated to 80°C, and stirred at a speed of 500 r / min for 30 min, 3 parts of rosin are added, the temperature is increased to 120°C, and stirring is performed at a speed of 500 r / min for 20 min to obtain a mixed solution I; (c) weighing 12 parts of graphite powder and adding it to the mixed solution I obtained in step (b), ultrasonically treating the mixture at a power of 0.5 kW for 30 minutes, heating the mixture to 110° C., and stirring the mixture at a speed of 500 rpm for 30 minutes to obtain a substrate mixture; (d) adding the alkalized straw powder obtained in step (a) to the base mixture, heating to 90° C., and stirring at a rotation speed of 500 r / min for 30 min to obtain a straw modified material precursor; (e) adding the clay powder obtained in step (a) to the straw modified product precursor obtained in step (d), heating the mixture to 60° C., stirring the mixture at a rotation speed of 500 r / min for 2 h, and introducing argon gas at a flow rate of 120 ml / min to obtain a straw modified product.

[0026] This embodiment also provides a method for preparing a straw aerogel composite insulation board, comprising the following steps: Step 1: Weigh 90 parts of the modified straw and 75 parts of the aerogel composite into 30 parts of KH550, and stir at a speed of 1500 r / min for 1 hour to obtain a mixture I; Step 2: Add 38 parts of phenolic resin to the mixture I obtained in step 1, and stir at a speed of 1500 r / min for 30 min to obtain a paste; Step 3: Pour the paste obtained in step 2 into a mold, and cure it at room temperature of 25°C under a cold pressing pressure of 10 MPa for 1 hour to obtain a solidified product; Step 4: Weigh 25 parts of antioxidant hydrophobic material and spray it evenly on the surface of the solidified material. At room temperature of 25°C, perform secondary cold pressing and solidification at a cold pressing pressure of 15 MPa for 2 hours to obtain a straw aerogel composite insulation board blank. Step 5: Place the straw aerogel composite insulation board blank obtained in step 4 in a ventilated environment for cross-linking for 72 hours, and place it in an oven at a temperature of 130° C. for 8 hours to obtain a straw aerogel composite insulation board.

[0027] Example 3: A straw aerogel composite insulation board is prepared from the following raw materials in parts by weight: 100 parts of straw modification, 85 parts of aerogel composite, 35 parts of antioxidant hydrophobic material, 45 parts of phenolic resin, and 30 parts of KH550; The preparation method of the antioxidant hydrophobe comprises the following steps: (a) Weighing 4 parts of natural rubber and adding it to 25 parts of a mixed solution of tetrahydrofuran and toluene, wherein the volume percentages of tetrahydrofuran and toluene in the mixed solution are 20%:80%, heating the mixture to 50°C and stirring at 500 r / min for 30 minutes to obtain a homogenized rubber solution; (β) Weighing 6 parts of aluminum oxide, drying them at 65° C. for 2 hours, and grinding them to obtain aluminum oxide powder, adding the aluminum oxide powder to the homogenizing solution obtained in step (α), and stirring at a speed of 500 r / min for 30 minutes to obtain an antioxidant homogenizing solution; (γ) Weigh 5 parts of carnauba wax and add it to the antioxidant homogeneous glue solution obtained in step (β). Heat it to 110° C. using a cooling reflux device and stir it at a speed of 500 r / min for 60 minutes. Seal it and store it for 5 hours to obtain an antioxidant hydrophobic substance.

[0028] The preparation method of the aerogel composite comprises the following steps: (I) Weighing 5.5 parts of graphene powder and 4.5 parts of nano-silicon dioxide into 15 parts of anhydrous ethanol, stirring at a speed of 300 r / min for 30 minutes to obtain a carbon-silicon mixed dispersion; (II) Weigh 9 parts of methyltrimethoxysilane and add it to the carbon-silicon mixed dispersion obtained in step (I), add 3 parts of glacial acetic acid, stir at a speed of 500 r / min for 40 minutes, seal and let it stand at 25°C for 24 hours to obtain an aerogel composite.

[0029] The preparation method of the modified straw comprises the following steps: (a) Weigh 20 parts of corn straw, dry them at 80°C for 6 h, grind them, and sieve them through a 20-mesh screen to obtain straw powder. The obtained straw powder is added to 50 parts of deionized water, the pH is adjusted to neutral by adding saturated sodium carbonate solution, washed with deionized water five times, and dried at 80°C for 12 h to obtain alkalized straw powder. Weigh 12 parts of kaolin, dry them at 110°C for 12 h, grind them, and sieve them through an 80-mesh screen to obtain clay fine powder. (b) Weigh 12 parts of epoxy resin, heat to 80°C, and stir at 500 r / min for 30 min. Add 3 parts of rosin, raise the temperature to 120°C, and stir at 500 r / min for 20 min to obtain a mixture I. (c) weighing 15 parts of graphite powder and adding it to the mixed solution I obtained in step (b), ultrasonically treating the mixture at a power of 0.5 kW for 30 minutes, heating the mixture to 110° C., and stirring the mixture at a speed of 500 rpm for 30 minutes to obtain a substrate mixture; (d) adding the alkalized straw powder obtained in step (a) to the base mixture, heating to 90° C., and stirring at a rotation speed of 500 r / min for 30 min to obtain a straw modified material precursor; (e) adding the clay powder obtained in step (a) to the straw modified product precursor obtained in step (d), heating the mixture to 60° C., stirring the mixture at a rotation speed of 500 r / min for 2 h, and introducing argon gas at a flow rate of 120 ml / min to obtain a straw modified product.

[0030] This embodiment also provides a method for preparing a straw aerogel composite insulation board, comprising the following steps: Step 1: Weigh 100 parts of the modified straw and 85 parts of the aerogel composite, add them to 30 parts of KH550, and stir at a speed of 1500 r / min for 1 hour to obtain a mixture I; Step 2: Add 45 parts of phenolic resin to the mixture I obtained in step 1, and stir at a speed of 1500 r / min for 30 min to obtain a paste; Step 3: Pour the paste obtained in step 2 into a mold, and cure it at room temperature of 25°C under a cold pressing pressure of 10 MPa for 1 hour to obtain a solidified product; Step 4: Weigh 35 parts of antioxidant hydrophobic material and spray it evenly onto the surface of the solidified material. Then, perform secondary cold pressing and solidification at a temperature of 25°C and a cold pressing pressure of 15 MPa for 2 hours to obtain a straw aerogel composite insulation board blank. Step 5: Place the straw aerogel composite insulation board blank obtained in step 4 in a ventilated environment for cross-linking for 72 hours, and place it in an oven at a temperature of 150° C. for 8 hours to obtain a straw aerogel composite insulation board.

[0031] The difference between Example 4 and Example 2 is that argon gas is replaced by nitrogen gas, and the rest is the same as Example 2.

[0032] Comparative Example: The difference between Comparative Example 1 and Example 2 is that no straw modification was added, and the rest of the process was the same as Example 2; The difference between Comparative Example 2 and Example 2 is that no aerogel composite is added, and the rest of the components are the same as Example 2; The difference between Comparative Example 3 and Example 2 is that no antioxidant hydrophobic substance is added, and the rest is the same as Example 2.

[0033] The performance of the straw aerogel composite insulation board obtained in the embodiment and the comparative example was tested respectively. Figure 3 This is a strength test diagram of the straw aerogel composite insulation board. It can be seen that the compressive strength and tensile strength of the straw aerogel composite insulation board prepared in the embodiment are better than those of the comparative example as a whole; Figure 4 Figure 2 is a test chart of thermal conductivity of the straw aerogel composite insulation board prepared in the embodiment and the comparative example. The overall thermal conductivity of the straw aerogel composite insulation board prepared in the embodiment is close to 0.01 W / m·K, showing high thermal insulation performance. The thermal conductivity test refers to GB / T 10294-2008. Figure 5 The loss rate and hydrophobicity test chart of the straw aerogel composite insulation board prepared for the examples and comparative examples is shown in the following table. The test conditions of the loss rate are as follows: the prepared straw aerogel composite insulation board is placed in an environment of 180℃ for 24h of continuous heating. It can be seen that the loss rate of the straw aerogel composite insulation board prepared in the examples is maintained within 2%, indicating that the material has good performance in heat resistance and oxidation resistance. The hydrophobicity test of the straw aerogel composite insulation board refers to GB / T 17657-2013, and the test results are shown in the following table. Figure 5 The data obtained by the test shows that the hydrophobicity of the straw aerogel composite insulation board reaches 99.5%, indicating excellent hydrophobicity. In addition, the data analysis and comparison of Example 4 and Example 2 do not change significantly when the argon is replaced by nitrogen, indicating that nitrogen can be used as an inert gas in the preparation process.

[0034] In summary, the straw aerogel composite insulation board prepared has good performance in strength, thermal insulation, oxidation resistance and hydrophobicity.

[0035] Obviously, the above comparative examples and examples are only a part of the comparative examples and examples of the present application, and the reference comparative examples and examples based on them are also within the scope of the present application.

[0036] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

[0037] The above describes the present application and its embodiments, which is not restrictive, and the embodiments shown in the drawings are only one of the embodiments of the present application, and the actual application is not limited thereto. In summary, if a person skilled in the art is inspired by it, without departing from the purpose of the present application, without creative design, similar ways and examples of the technical solution should belong to the protection scope of the present application.

Claims

1. A straw aerogel composite insulation board, characterized in that: The invention is prepared from the following raw materials in parts by weight: 80-100 parts of straw modification, 65-85 parts of aerogel compound, 15-35 parts of antioxidant hydrophobic material, 30-45 parts of phenolic resin and 30 parts of silane coupling agent; The raw materials for preparing the straw modified material include straw, carbon-based material, clay, epoxy resin and rosin, and the mass ratio of the straw, carbon-based material, clay, epoxy resin and rosin is 15-20:9-15:8-12:10-12:3; The raw materials for preparing the aerogel composite include graphene powder, nano-silica and methyltrimethoxysilane, and the mass ratio of the graphene powder, nano-silica and methyltrimethoxysilane is 3.5-5.5:4.5:6-9; The raw materials for preparing the antioxidant hydrophobic compound include aluminum oxide, natural rubber and vegetable wax, and the mass ratio of the aluminum oxide, natural rubber and vegetable wax is 4-6:2-4:

5.

2. The straw aerogel composite insulation board according to claim 1, characterized in that: The method for preparing the modified straw comprises the following steps: (a) weighing straw, drying, crushing, and sieving to obtain straw powder, adding the obtained straw powder to deionized water, adding salt solution to adjust the pH, washing, and drying to obtain alkalized straw powder, weighing clay, drying, grinding, and sieving to obtain clay fine powder; (b) Weighing epoxy resin, heating and stirring, adding rosin, and heating and stirring to obtain a mixed solution I; (c) weighing a carbon-based material and adding it to the mixed solution I obtained in step (b), sonicating, heating, and stirring to obtain a substrate mixture; (d) adding the alkalized straw powder obtained in step (a) to the base mixture, heating and stirring to obtain a straw modified material precursor; (e) adding the clay powder obtained in step (a) to the straw modified product precursor obtained in step (d), heating and stirring, to obtain a straw modified product.

3. The straw aerogel composite insulation board according to claim 2, characterized in that: The straw described in step (a) is corn straw, the clay is kaolin, the salt solution is a saturated sodium carbonate solution, the pH is neutral, the straw screening mesh is 20 mesh, the clay screening mesh is 80 mesh, and the carbon-based material described in step (c) is graphite powder.

4. The straw aerogel composite insulation board according to claim 1, characterized in that: The method for preparing the aerogel composite comprises the following steps: (I) weighing graphene powder and nano-silicon dioxide, adding them to anhydrous ethanol, and stirring to obtain a carbon-silicon mixed dispersion; (II) Weighing methyltrimethoxysilane and adding it to the carbon-silicon mixed dispersion obtained in step (I), adding acid solution, stirring, sealing and allowing to stand, to obtain an aerogel composite.

5. The straw aerogel composite insulation board according to claim 4, characterized in that: The acid solution in step (II) is glacial acetic acid, the standing temperature is 25° C., and the standing time is 24 h.

6. The straw aerogel composite insulation board according to claim 1, characterized in that: The preparation method of the antioxidant hydrophobe comprises the following steps: (a) weighing natural rubber and adding it to a mixed solution of tetrahydrofuran and toluene, heating and stirring to obtain a homogeneous rubber solution; (β) weighing aluminum oxide, drying it, and grinding it to obtain aluminum oxide powder, adding the aluminum oxide powder to the homogenizing solution obtained in step (α), and stirring to obtain an antioxidant homogenizing solution; (γ) Weighing the vegetable wax and adding it to the antioxidant homogeneous glue solution obtained in step (β), heating and stirring, and sealing and storing to obtain an antioxidant hydrophobic substance.

7. The straw aerogel composite insulation board according to claim 6, characterized in that: The volume percentages of tetrahydrofuran and toluene in the mixed solution of tetrahydrofuran and toluene in step (α) are 20%:80%, and the plant wax in step (γ) is carnauba wax.

8. A method for preparing a straw aerogel composite insulation board according to any one of claims 1 to 7, characterized in that: The steps include: Step 1: weighing the modified straw and the aerogel composite, adding them to a silane coupling agent, and stirring to obtain a mixture I; Step 2: adding phenolic resin to the mixture I obtained in step 1, stirring to obtain a paste; Step 3: pour the paste obtained in step 2 into a mold, and cold press and solidify it to obtain a solidified product; Step 4: Weighing an antioxidant hydrophobic substance and spraying it onto the surface of the solidified material, and then cold-pressing and solidifying it for a second time to obtain a straw aerogel composite insulation board; Step 5: Place the straw aerogel composite insulation board blank obtained in step 4 in a ventilated environment for cross-linking, and place it in an oven for treatment to obtain a straw aerogel composite insulation board.

9. The method for preparing a straw aerogel composite insulation board according to claim 8, characterized in that: The silane coupling agent described in step 1 is KH550, the cold pressing pressure in step 3 is 10MPa, the cold pressing time is 1h, the secondary cold pressing pressure in step 4 is 15MPa, the cold pressing time is 2h,, the cross-linking time in step 5 is 72h, the oven temperature is 110-150℃, and the heating time is 8h.

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