Body-enhanced nano thermal insulation board and preparation method thereof

Abstract

The invention belongs to the technical field of nano composite thermal insulation materials, and particularly relates to a body-enhanced nano thermal insulation board and a preparation method thereof.The body-enhanced nano thermal insulation board is prepared by pre-coating high-temperature-resistant filler with methyl cellulose to form microsphere particles, uniformly dispersing the microsphere particles in raw materials in the dry-method mixing stage, and conducting low-temperature mold pressing and thermal treatment to enable the methyl cellulose to be crosslinked and cured in the board. A three-dimensional reinforced network penetrating through the fibers and the powder is formed. According to the method, surface coating or high-pressure treatment is not needed, the body strength (tensile strength / bending strength / interlayer strength is improved by 100% +) is directly improved, the proper density (200-600 kg / m) and the excellent heat insulation performance (the increase of the heat conductivity coefficient is smaller than or equal to 5%) are kept, the cost is low, the process is simple, and the method is suitable for industrial continuous production.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite thermal insulation materials technology, specifically relating to a bulk-reinforced nano-thermal insulation board and its preparation method. Technical Background

[0002] Nano-insulation panels are a type of high-efficiency thermal insulation material that has been developed in the last two years. They are made based on the excellent thermal insulation properties of nanoporous materials. Traditional nano-insulation panels are made by dry mixing of inorganic nanoparticles (such as aerogel, fumed silica, etc.), reinforcing fibers, light-blocking agents, and high-temperature resistant fillers, followed by low-pressure molding.

[0003] Existing technologies, such as Chinese Patent Publication No. CN118894710B, provide a nano-silica microporous insulation board and its preparation method. By adding composite ceramic fibers and a composite binder, the mechanical properties of the microporous insulation board can be improved. The bonding ability of the composite binder at high temperatures avoids the shrinkage and cracking problem of the microporous insulation board caused by high temperatures, thus solving the problems of insufficient compressive strength and thermal insulation performance of existing nano-microporous insulation boards. At the same time, it can still maintain good mechanical properties under high-temperature conditions. However, existing nano-insulation materials have the following technical problems: First, the inherent strength of nano-insulation materials is weak. They rely solely on physical pressing to form a bond between raw materials, lacking effective chemical connections between the fibers and powder. This results in most nano-insulation materials having tensile strength less than 0.4 MPa, flexural strength less than 0.6 MPa, and interlayer strength (peel strength) less than 0.3 MPa. Consequently, the prepared insulation boards are prone to breakage and powdering during use. Existing patents related to nano-insulation boards focus on optimizing insulation performance or pressing equipment, without addressing the issue of inherent strength. Second, surface coatings have limitations. Existing coatings only improve... While improving the surface strength of the board is important, it cannot improve the bonding force between the fiber and powder interface inside the board, resulting in low interlayer strength. Therefore, delamination and powder shedding occur during use. Thirdly, there is a performance contradiction: the coating of existing boards is too thick (generally >50μm), increasing production costs and thermal conductivity by >15%. While high-pressure pressing (generally >3MPa) in existing technologies can improve strength, it leads to excessive board density (>600kg / m³), increasing thermal conductivity by more than 30%, severely affecting the board's insulation performance. Therefore, there is an urgent need to develop a nano-insulation board with sufficient body strength while also possessing high strength and low thermal conductivity. Summary of the Invention

[0004] The purpose of this invention is to provide a bulk-reinforced nano-insulation board and its preparation method. By using a special bulk reinforcing agent, the bonding force between fibers and powders in the raw materials can be enhanced, thereby increasing the strength of the nano-insulation board and reducing its thermal conductivity.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A bulk-reinforced nano-insulation panel comprises the following components by weight fraction: 50–70% inorganic nanoparticles; 1–40% reinforcing fibers; 1–30% light-blocking agent; and 1–5% bulk reinforcing agent.

[0006] Furthermore, the inorganic nanoparticles are nano-silica aerogels or fumed silica.

[0007] Furthermore, the reinforcing fiber is a ceramic fiber or a high-silica fiber, and the length of the reinforcing fiber is 1-6 mm.

[0008] Furthermore, the light-blocking agent is silicon carbide or titanium dioxide.

[0009] Furthermore, the bulk reinforcing agent comprises methylcellulose and high-temperature resistant filler, wherein the mass ratio of methylcellulose to high-temperature resistant filler is 1:5–1:10, the high-temperature resistant filler comprises hollow aluminum silicate microspheres, and the particle size of the bulk reinforcing agent is 10-50 μm.

[0010] This invention also provides a method for preparing a bulk-reinforced nano-insulation plate, comprising the following steps: Step 1: Mix methylcellulose and high-temperature resistant filler according to the mass ratio, add deionized water and stir to prepare bulk reinforcing agent; Step 2: Weigh the raw materials according to the proportions and then mix them using a high-speed dry method to form a mixture; Step 3: Load the mixture into a mold, press it into a green sheet at a low temperature, and dry the green sheet to make a heat insulation board.

[0011] Furthermore, in step one, the amount of deionized water added is 40-60% of the total mass of methylcellulose and high-temperature resistant filler, the stirring temperature is 50-60℃, and the stirring time is 30-60min.

[0012] Furthermore, in step two, the mixing speed is 200-400 rpm and the mixing time is 8-15 min.

[0013] Furthermore, in step three, the pressing temperature is 40-60℃, the pressing pressure is 0.5-1.5MPa, and the pressing time is 10-25s.

[0014] Furthermore, in step three, the drying temperature is 100-120℃ and the drying time is 10-20 minutes.

[0015] Beneficial effects: 1. In the preparation process of this invention, the bulk reinforcing agent is heat-treated, which enables the MC-coated microspheres to form a continuous network inside the board, enhancing the fiber-powder interface bonding force and increasing the interlayer strength to ≥0.3MPa (peel strength), solving the interlayer delamination problem. The tensile / flexural strength reaches 0.3–0.5MPa / 0.5–0.7MPa, with typical values ​​as shown in Example 1, tensile strength 0.44 MPa, and flexural strength 0.66 MPa, which is more than 100% higher than the traditional method.

[0016] 2. In this invention, the amount of methylcellulose used is only 1–3%, which is much lower than the amount of coating (15–40 g / m²). It does not fill the nanopores and can reduce the increase in thermal conductivity by ≤5% (0.019→0.020 W / (m·K)), which is far superior to the coating solution (increase >15%).

[0017] 3. Compared with using resin coating as a bulk reinforcing agent, the bulk reinforcing agent in this invention is inexpensive, requires no spraying equipment or infrared drying during preparation, can be seamlessly integrated with existing dry production lines, only requires the addition of an MC pretreatment unit, has a curing time of ≤20 minutes, and the board density is stable at 200–600 kg / m³, making it suitable for new energy battery packs, industrial furnaces, building insulation and other scenarios.

[0018] 4. Compared with traditional coating solutions (thermal conductivity increase >15%) or high-pressure molding (density >600 kg / m³), this invention achieves double the body strength while maintaining low density and ultra-low thermal conductivity, solving the technical problem of 'strength-lightweight-thermal insulation'. Detailed Implementation

[0019] The technical solution of this application is further illustrated below through specific embodiments.

[0020] Unless otherwise specified, all raw materials used in this application are derived from commercially available materials.

[0021] Example 1 This embodiment provides a bulk-reinforced nano-insulation board, comprising the following components by weight: 60% inorganic nanoparticles, 30% reinforcing fibers, 5% light-blocking agent, and 5% bulk reinforcing agent. The inorganic nanoparticles are selected from nano-silica aerogel, the reinforcing fibers are ceramic fibers with a length of 6 mm, the light-blocking agent is silicon carbide, and the bulk reinforcing agent is a mixture of methylcellulose and aluminum silicate hollow microspheres at a ratio of 1:8.

[0022] This embodiment also provides a method for preparing a bulk-reinforced nano-insulation plate, including the following steps: Methylcellulose (MC) and hollow aluminum silicate microspheres were mixed at a ratio of 1:8, and 55% of the total solid mass of deionized water was added. The mixture was stirred at 55°C for 45 minutes to obtain a bulk reinforcing agent. Then, the raw materials were weighed according to the above weight fractions and mixed at 300 rpm for 10 minutes to ensure uniform mixing. After uniform mixing, the mixture was placed in a mold and pressed at 1.0 MPa and 50°C for 20 seconds, followed by drying in a hot air environment at 110°C for 15 minutes to obtain a nano-insulation board. Testing showed that the nano-insulation board prepared in this embodiment had a tensile strength of 0.44 MPa, a flexural strength of 0.66 MPa, an interlaminar strength of 0.33 MPa, a thermal conductivity of 0.020 W / (m·K), no powder shedding during use, and a density of 310 kg / m³.

[0023] Example 2 This embodiment provides a bulk-reinforced nano-insulation board, comprising the following components by weight: 68% inorganic nanopowder, 25% reinforcing fiber, 4% light-blocking agent, and 3% bulk reinforcing agent. The inorganic nanopowder is fumed silica, the reinforcing fiber is high-silica fiber with a length of 3 mm, the light-blocking agent is titanium dioxide, and the bulk reinforcing agent is a mixture of methylcellulose and aluminum silicate hollow microspheres in a 1:6 ratio.

[0024] This embodiment also provides a method for preparing a bulk-reinforced nano-insulation plate, including the following steps: Methylcellulose (MC) and hollow aluminum silicate microspheres were mixed at a ratio of 1:6, and 50% of the total solid mass of deionized water was added. The mixture was stirred at 55°C for 40 min to obtain a bulk reinforcing agent. Then, the raw materials were weighed according to the above weight fractions and mixed at 350 rpm for 12 min to ensure uniform mixing. After uniform mixing, the mixture was placed in a mold and pressed at 0.8 MPa and 50°C for 15 s, followed by drying in a hot air environment at 110°C for 12 min to obtain a nano-insulation board. Testing showed that the nano-insulation board prepared in this embodiment had a tensile strength of 0.38 MPa, a flexural strength of 0.61 MPa, an interlaminar strength of 0.31 MPa, and a thermal conductivity of 0.0195 W / (m·K). No powder was shed during use, and the density of the prepared nano-insulation board was 280 kg / m³.

[0025] Example 3 This embodiment provides a bulk-reinforced nano-insulation board, comprising the following components by weight: inorganic nanopowder: 50%, reinforcing fiber: 40%, light-blocking agent: 7%, and bulk reinforcing agent: 3%. The inorganic nanopowder is selected from nano-SiO2 aerogel, the reinforcing fiber is ceramic fiber (6mm), the light-blocking agent is silicon carbide, and the bulk reinforcing agent is a mixture of methylcellulose and aluminum silicate hollow microspheres at a ratio of 1:10.

[0026] This embodiment also provides a method for preparing a bulk-reinforced nano-insulation plate, including the following steps: Methylcellulose (MC) and hollow aluminum silicate microspheres were mixed at a ratio of 1:10, and 60% of the total solid mass of deionized water was added. The mixture was stirred at 60°C for 60 min to obtain a bulk reinforcing agent. Then, the raw materials were weighed according to the above weight fractions and mixed at 220 rpm for 15 min to ensure uniform mixing. After uniform mixing, the mixture was placed in a mold and pressed at 0.5 MPa and 40°C for 25 s, followed by drying in a hot air environment at 120°C for 20 min to obtain a nano-insulation board. Testing showed that the nano-insulation board prepared in this embodiment had a tensile strength of 0.32 MPa, a flexural strength of 0.52 MPa, an interlaminar strength of 0.28 MPa, a thermal conductivity of 0.020 W / (m·K), no powder shedding during use, and a density of 580 kg / m³.

[0027] Comparative Example 1 The difference between this comparative example and the embodiment is that methylcellulose coating was not used, while the other components and their weight fractions are the same. The specific preparation process is as follows: The raw materials were weighed according to the following mass fractions: 60% inorganic nanoparticles; 30% reinforcing fibers; 3% opacifier; and 7% aluminum silicate hollow microspheres. The mixture was then stirred at 300 rpm for 10 minutes to ensure uniform mixing. After uniform mixing, the mixture was placed in a mold and pressed at 1.0 MPa and 50°C for 20 seconds. Subsequently, it was dried in a hot air environment at 110°C for 15 minutes to obtain the nano-insulation board. Testing showed that the nano-insulation board prepared in this comparative example had a tensile strength of 0.19 MPa, a flexural strength of 0.27 MPa, an interlaminar strength of 0.12 MPa, and a thermal conductivity of 0.019 W / (m·K).

[0028] Comparative Example 2 The difference between this comparative example and Example 1 lies in the preparation method. The specific preparation method is as follows: Methylcellulose (MC) and hollow aluminum silicate microspheres were mixed at a ratio of 1:8. Then, the raw materials were weighed according to the following weight fractions: 60% inorganic nanopowder, 30% reinforcing fiber, 3% opacifier, and 7% bulk reinforcing agent. The mixture was stirred at 300 rpm for 10 minutes to ensure uniform mixing. After uniform mixing, the mixture was placed in a mold and pressed at 1.0 MPa and 50°C for 20 seconds. Subsequently, it was dried in a hot air environment at 110°C for 15 minutes to obtain a nano-insulation board. Testing showed that the nano-insulation board prepared in this embodiment had a tensile strength of 0.32 MPa, a flexural strength of 0.041 MPa, an interlaminar strength of 0.19 MPa, and a thermal conductivity of 0.021 W / (m·K).

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and not restrictive in all respects. Furthermore, it should be understood that although this specification describes embodiments, it does not encompass only one technical solution. This descriptive method is merely for clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A bulk-reinforced nano-insulation panel, characterized in that: It comprises the following components: 50–70% inorganic nanoparticles; 1–40% reinforcing fibers; 1–30% opacifier; and 1–5% bulk reinforcing agent.

2. The bulk-reinforced nano-insulation panel according to claim 1, characterized in that: The inorganic nanopowder is nano-silica aerogel or fumed silica.

3. The bulk-reinforced nano-insulation panel according to claim 1, characterized in that: The reinforcing fiber is a ceramic fiber or a high-silica fiber, and the length of the reinforcing fiber is 1-6 mm.

4. The bulk-reinforced nano-insulation panel according to claim 1, characterized in that: The light-blocking agent is silicon carbide or titanium dioxide.

5. The bulk-reinforced nano-insulation panel according to claim 1, characterized in that: The bulk reinforcing agent comprises methylcellulose and high-temperature resistant filler, wherein the mass ratio of methylcellulose to high-temperature resistant filler is 1:5–1:10, the high-temperature resistant filler comprises high-temperature resistant inorganic hollow microspheres, and the particle size of the bulk reinforcing agent is 10-50 μm.

6. The method for preparing the bulk-reinforced nano-insulation plate according to any one of claims 1-5, characterized in that: Step 1: Mix methylcellulose and high-temperature resistant filler according to the mass ratio, add deionized water and stir to prepare bulk reinforcing agent; Step 2: Weigh the raw materials according to the proportions and then mix them using a high-speed dry method to form a mixture; Step 3: Load the mixture into a mold, press it into a green sheet at a low temperature, and dry the green sheet to make a heat insulation board.

7. The method for preparing the bulk-reinforced nano-insulation plate according to claim 6, characterized in that: In step one, the amount of deionized water added is 40-60% of the total mass of methylcellulose and high-temperature resistant filler, the stirring temperature is 50-60℃, and the stirring time is 30-60min.

8. The method for preparing the bulk-reinforced nano-insulation plate according to claim 6, characterized in that: In step two, the mixing speed is 200-400 rpm and the mixing time is 8-15 min.

9. The method for preparing the bulk-reinforced nano-insulation plate according to claim 6, characterized in that: In step three, the pressing temperature is 40-60℃, the pressing pressure is 0.5-1.5MPa, and the pressing time is 10-25s.

10. The method for preparing the bulk-reinforced nano-insulation plate according to claim 6, characterized in that: In step three, the drying temperature is 100-120℃ and the drying time is 10-20 minutes.