Continuous dry-forming thermal insulation composite material and preparation method and application thereof

Abstract

This invention relates to the field of thermal insulation materials, and discloses a continuous dry-molding thermal insulation composite material, its preparation method, and its application. The thermal insulation composite material comprises the following raw materials: 20-55 wt% glass fiber, 5-10 wt% basalt fiber, 3-7 wt% PP fiber, 15-25 wt% hydrophobic SiO2 particles, 7-16.5 wt% hollow ceramic microspheres, and 1.5-5.5 wt% powder binder; the powder binder is double-layer PVDF-coated titanium dioxide. The thermal insulation composite material of this invention simultaneously possesses high structural stability, high thermal insulation performance, and high compression resilience. The thermal insulation composite material of this invention can be obtained through a continuous dry molding process, which is simple, has high production efficiency, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials, and in particular to a continuous dry-molded thermal insulation composite material, its preparation method, and its application. Background Technology

[0002] Currently, most mainstream battery thermal management systems use aerogel felt materials for insulation. Aerogel felt materials are mainly prepared and molded using supercritical processes to ensure their high thermal insulation performance (e.g., CN202510759591.9). The disadvantages of supercritical processes are low production efficiency and high cost. In addition, the pore structure formed by supercritical processes in the resulting aerogel felt materials is not stable. Under the influence of external forces or high temperatures, the structure is prone to collapse, leading to a significant decrease in its thermal insulation performance during long-term use.

[0003] Another type of fiber insulation material, which is formed by traditional wet bonding and dry hot pressing processes, has problems such as low porosity and poor recovery after being compressed (generally <40%) (in the field of power batteries, insulation sheets need to maintain high compression recovery performance under certain pressure conditions during use).

[0004] In summary, there is a need to develop a thermal insulation material that simultaneously possesses high structural stability, high thermal insulation performance, and high compression resilience. Furthermore, the preparation method of this thermal insulation material needs to be simple, have high production efficiency, and be suitable for large-scale industrial production. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a continuous dry-molding thermal insulation composite material, its preparation method, and its applications. The thermal insulation composite material of this invention simultaneously possesses high structural stability, high thermal insulation performance, and high compression resilience. This thermal insulation composite material can be obtained through a continuous dry molding process, which is simple, has high production efficiency, and is suitable for large-scale industrial production.

[0006] The specific technical solution of the present invention includes: In a first aspect, the present invention provides a continuous dry-molded thermal insulation composite material, comprising the following raw materials: 20-55 wt% glass fiber, 5-10 wt% basalt fiber, 3-7 wt% PP fiber, 15-25 wt% hydrophobic SiO2 particles, 7-16.5 wt% hollow ceramic microspheres, and 1.5-5.5 wt% powder binder. The powder binder is double-layer PVDF-coated titanium dioxide.

[0007] In the above formulation of the present invention, the characteristics and functions of each raw material are as follows: Glass fiber and basalt fiber: as the main materials, they can be intertwined to form the base material of thermal insulation composite materials. Glass fiber and basalt fiber have good mechanical properties and thermal insulation properties.

[0008] PP fiber: As a fibrous "adhesive," PP fiber, unlike ordinary adhesives, melts locally when heated. Unlike liquid adhesives, it does not flow and block the material's pores, thus preventing a decrease in thermal insulation performance. During the molding process, PP fiber can entangle with and bond with inorganic fibers to create bonding nodes, forming a stable pore structure that increases the material's thermal insulation stability and compression resilience. Hydrophobic SiO2 particles and hollow ceramic microspheres: As thermal insulation fillers, they can be combined to form pore structures of different sizes.

[0009] Powder binder: A double-layer PVDF-coated titanium dioxide. The titanium dioxide acts as a light-shielding agent, preventing radiative heat penetration and further improving thermal insulation performance and stability. Due to the presence of the PVDF coating, titanium dioxide particles can stack and cross-link with other inorganic particles and fibers to form a self-healing porous structure. Specifically, the PVDF coating undergoes fiberization during the extrusion shearing process after mixing (i.e., the PVDF coating is drawn into filaments under shear force), serving as a bonding point with other powders and fibers, thus forming a multi-morphological network structure. This structure exhibits excellent stability, not only increasing the bonding rate between powders and fibers but also enhancing the material's compression resilience. The reason for using a double-layer PVDF coating for titanium dioxide in this invention is that we found that single-layer PVDF is unstable in fiberization during shearing, with a fiberization rate of only about 50%; while the fiberization rate of double-layer PVDF can be increased to over 85% under the same conditions, thus significantly enhancing the material's mechanical properties (especially compression resilience).

[0010] In summary, under the shear force during the preparation process, the thermal insulation composite material prepared from the above-mentioned raw materials of this invention possesses an interpenetrating network three-dimensional skeleton: under the action of PP fiber adhesive, the intertwined inorganic fibers serve as the skeleton, and powders of different particle sizes construct a richer pore structure. The thermal insulation composite material of this invention not only possesses high porosity, high structural stability, and high thermal insulation properties, but the presence of double-layer PVDF-coated titanium dioxide also endows it with excellent compressive resilience.

[0011] Furthermore, this invention has discovered that the content of PP fiber and double-layer PVDF-coated titanium dioxide has a significant impact on various properties of the thermal insulation composite material. Specifically, if the PP fiber content is too low, it will lead to a decrease in strength; conversely, if its content is too high, it will lead to an increase in thermal conductivity, affecting the thermal insulation effect. If the content of double-layer PVDF-coated titanium dioxide is too low, it cannot effectively bind the powder, and its improvement on the compression resilience of the thermal insulation composite material is not significant; if its content is too high, it will easily reduce the porosity of the thermal insulation composite material, resulting in poor thermal insulation performance.

[0012] Preferably, the particle size D50 of the double-layer PVDF-coated titanium dioxide is 10-15 μm; the thickness of the inner PVDF layer is 2.5-3.5 μm, and the thickness of the outer PVDF layer is 1-2 μm.

[0013] Through repeated experiments, it was found that controlling the particle size of the double-layer PVDF-coated titanium dioxide and the thickness of the inner / outer PVDF layers within the above-mentioned range resulted in the best improvement effect on the compression resilience of the thermal insulation composite material.

[0014] Preferably, the basalt fiber has a diameter of 7-9 μm and a tensile strength ≥2500 MPa after heat treatment at 650℃.

[0015] Preferably, the glass fiber has a diameter of 2-4 μm, a SiO2 content of ≥96 wt%, and a softening point of ≥1650℃.

[0016] Preferably, the diameter of the PP fiber is 3-8 μm.

[0017] Preferably, the hydrophobic SiO2 particles have a D50 of 0.01-0.03 μm and a specific surface area of ​​300-500 m². 2 / g. Preferably, the wall thickness / diameter ratio of the hollow ceramic microspheres is 1:15-25.

[0018] Preferably, the hydrophobic SiO2 particles are SiO2 particles that have been surface modified with a silane coupling agent. The preparation method includes: heating an aqueous solution containing 3-7 wt% silane coupling agent to 55-65°C, adding SiO2 particles in batches under stirring, and spray-drying the resulting liquid to obtain hydrophobic SiO2 particles.

[0019] Preferably, the hollow ceramic microspheres undergo plasma surface treatment under the following conditions: nitrogen plasma is used, with a power of 15-250W and a time of 10-20min.

[0020] By modifying the surface of hydrophobic SiO2 particles and hollow ceramic microspheres, the electrostatic force and van der Waals force between particles can be reduced, the friction between particles can be reduced, and the particles can be prevented from agglomerating during the preparation process, resulting in a more uniform pore structure between particles after molding.

[0021] Secondly, the present invention provides a method for preparing a continuous dry-molded thermal insulation composite material, which includes the following steps: 1) Titanium dioxide powder was surface-treated with tridecafluorooctyltriethoxysilane and spray-dried to obtain modified titanium dioxide powder; the modified titanium dioxide powder was dispersed in a solvent containing PVDF, and the resulting slurry was dropped into water under heating and stirring, and after post-treatment, an inner layer of PVDF-coated titanium dioxide was obtained; the inner layer of PVDF-coated titanium dioxide was dispersed in a solvent containing PVDF, and the resulting slurry was dropped into water under heating and stirring, and after post-treatment, a double layer of PVDF-coated titanium dioxide was obtained.

[0022] 2) Mix all raw materials into a dough-like consistency, and then process and extrude the dough using a screw extruder to obtain sheet-like heat-insulating composite material.

[0023] This invention prepares thermal insulation composite materials through a continuous dry molding process. By optimizing the ratio of PP fiber to powder binder, it achieves the elimination of secondary compression molding (allowing for the one-time molding of ultra-thin thermal insulation sheets). Therefore, the method of this invention is simple, has high production efficiency, and is suitable for large-scale industrial production.

[0024] Preferably, in step 1), the solvent is N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP).

[0025] The advantage of using the above solvents is that they have high boiling points and high solubility for PVDF.

[0026] Preferably, in step 1), the concentration of PVDF in the solvent containing PVDF is 15-20 wt% during the first drop addition; and the concentration of PVDF in the solvent containing PVDF is 10-14 wt% during the second drop addition.

[0027] Preferably, in step 1), the solvent containing PVDF further contains: 0.05-0.15 wt% polyvinylpyrrolidone (PVP) or 0.03-0.07 wt% sodium dodecyl sulfate (SDS).

[0028] The above-mentioned substances can act as space / charge stabilizers to prevent secondary agglomeration of modified titanium dioxide powder.

[0029] Preferably, in step 1), the dripping rate of the slurry is 0.8-1.2 mL / min; and the mass ratio of the slurry to water is 1:8-12.

[0030] Preferably, in step 2), the die width of the screw extruder is >200mm and the thickness is 1-3mm.

[0031] Thirdly, the present invention provides the application of the above-mentioned continuously dry-molded thermal insulation composite material as a battery thermal insulation sheet.

[0032] Compared with the prior art, the beneficial effects of the present invention are: (1) The thermal insulation composite material of the present invention has an interpenetrating network three-dimensional skeleton: under the action of PP fiber adhesive, the intertwined inorganic fibers serve as the skeleton, and powders of different particle sizes construct a richer pore structure. The thermal insulation composite material of the present invention has the characteristics of high structural stability and high thermal insulation.

[0033] (2) This invention uses double-layer PVDF-coated titanium dioxide as a powder binder. Titanium dioxide acts as a light-shielding agent, preventing radiative heat penetration and further improving thermal insulation performance and stability. The PVDF coating layer can fiberize under shear force, promoting the stacking and cross-linking of titanium dioxide particles with other inorganic particles and fibers to form a self-healing porous structure. This structure has excellent stability, not only increasing the bonding rate of powder and fibers but also increasing the compressive resilience of the material.

[0034] (3) The present invention prepares thermal insulation composite material through a continuous dry molding process. By optimizing the ratio of PP fiber to powder binder, it achieves the elimination of secondary compression molding (ultra-thin thermal insulation sheet can be formed in one step). Therefore, the method of the present invention is simple, has high production efficiency, and is suitable for large-scale industrial production. Attached Figure Description

[0035] Figure 1 The image shows a scanning electron microscope (SEM) image (scale bar 100 μm) of the thermal insulation composite material prepared in Example 2.

[0036] Figure 2 The image shows a scanning electron microscope (SEM) image (scale bar 10 μm) of the thermal insulation composite material prepared in Example 2. Detailed Implementation

[0037] The present invention will be further described below with reference to embodiments.

[0038] General Implementation Examples First, a continuous dry-forming thermal insulation composite material comprises the following raw materials: 20-55 wt% glass fiber, 5-10 wt% basalt fiber, 3-7 wt% PP fiber, 15-25 wt% hydrophobic SiO2 particles, 7-16.5 wt% hollow ceramic microspheres, and 1.5-5.5 wt% powder binder. The powder binder is double-layer PVDF-coated titanium dioxide.

[0039] In some embodiments, the particle size D50 of the double-layer PVDF-coated titanium dioxide is 10-15 μm; the thickness of the inner PVDF layer is 2.5-3.5 μm, and the thickness of the outer PVDF layer is 1-2 μm.

[0040] In some embodiments, the basalt fiber has a diameter of 7-9 μm and a tensile strength ≥2500 MPa after heat treatment at 650℃.

[0041] In some embodiments, the glass fiber has a diameter of 2-4 μm, a SiO2 content of ≥96 wt%, and a softening point of ≥1650℃.

[0042] In some embodiments, the diameter of the PP fiber is 3-8 μm.

[0043] In some embodiments, the hydrophobic SiO2 particles have a D50 of 0.01-0.03 μm and a specific surface area of ​​300-500 m². 2 / g. In some embodiments, the wall thickness / diameter ratio of the hollow ceramic microspheres is 1:15-25.

[0044] In some embodiments, the hydrophobic SiO2 particles are SiO2 particles that have been surface modified with a silane coupling agent. The preparation method includes: heating an aqueous solution containing 3-7 wt% silane coupling agent to 55-65°C, adding SiO2 particles in batches while stirring, and spray-drying the resulting liquid to obtain hydrophobic SiO2 particles.

[0045] In some embodiments, the hollow ceramic microspheres undergo plasma surface treatment under the following conditions: nitrogen plasma is used, with a power of 15-250W and a time of 10-20 minutes.

[0046] Secondly, a method for preparing a continuous dry-molded thermal insulation composite material includes the following steps: 1) Titanium dioxide powder was surface-treated with tridecafluorooctyltriethoxysilane and spray-dried to obtain modified titanium dioxide powder; the modified titanium dioxide powder was dispersed in a solvent containing PVDF, and the resulting slurry was dropped into water under heating and stirring, and after post-treatment, an inner layer of PVDF-coated titanium dioxide was obtained; the inner layer of PVDF-coated titanium dioxide was dispersed in a solvent containing PVDF, and the resulting slurry was dropped into water under heating and stirring, and after post-treatment, a double layer of PVDF-coated titanium dioxide was obtained.

[0047] The formation principle of the inner and outer PVDF layers is as follows: when the slurry is dropped into water, the solvent diffuses rapidly → PVDF precipitates in situ and coats the modified titanium dioxide powder, thereby forming the inner and outer PVDF layers respectively.

[0048] In some embodiments, in step 1), the solvent is N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP).

[0049] In some embodiments, in step 1), the concentration of PVDF in the solvent containing PVDF is 15-20 wt% during the first drop addition; and the concentration of PVDF in the solvent containing PVDF is 10-14 wt% during the second drop addition.

[0050] In some embodiments, in step 1), the solvent containing PVDF further contains: 0.05-0.15 wt% polyvinylpyrrolidone (PVP) or 0.03-0.07 wt% sodium dodecyl sulfate (SDS).

[0051] In some implementations, in step 1), the dripping rate of the slurry is 0.8-1.2 mL / min; the mass ratio of the slurry to water is 1:8-12.

[0052] 2) Mix all raw materials into a dough-like consistency, and then process and extrude the dough using a screw extruder to obtain sheet-like heat-insulating composite material.

[0053] In some implementations, in step 2), the die width of the screw extruder is >200mm and the thickness is 1-3mm.

[0054] Finally, a battery heat insulation sheet was prepared using the above-mentioned continuous dry molding method.

[0055] Specific embodiments and comparative examples (I) Effect of different powder binder (double-layer PVDF-coated titanium dioxide) contents on the performance of thermal insulation composite materials The formulations of Examples 1-3 and Comparative Examples 1-3 are shown in Table 1: Table 1 The specifications of the raw materials in the table above are as follows: Glass fiber: diameter 2-4μm, SiO2 content ≥96wt%, softening point ≥1650℃, Shandong Glass Fiber HS2-96; Basalt fiber: monofilament diameter 7-9μm, tensile strength ≥2500MPa after heat treatment at 650℃, Zhejiang Shijin BF10-650; PP fiber: diameter 3-8μm; Hydrophobic SiO2 particles: D50≈0.02μm, specific surface area approximately 380m² 2 / g, Cabot, CAB-I-SIL®TS-530; Hollow ceramic microspheres: particle size D50=3-5μm, wall thickness / diameter ratio 1:20, 3M TM C-Bubbles iM30K (custom grade); Double-layer PVDF-coated titanium dioxide: particle size D50≈12μm; inner PVDF layer thickness approximately 3μm, outer PVDF layer thickness approximately 1.5μm.

[0056] The preparation method of the above-mentioned thermal insulation composite material includes the following steps: 1) Surface modification of hydrophobic SiO2 particles: Prepare 70 kg of 5 wt% KH-560 aqueous solution, heat to 60℃, stir at 1500 rpm, add 10 kg of SiO2 particles to the stirring liquid in 3 batches, with an interval of 10 minutes between each addition. After the SiO2 particles are added, continue stirring for 30 minutes and then stop heating. Allow to cool naturally, pour the liquid into a spray drying equipment for spray drying, collect the powder, and obtain hydrophobic SiO2 particles.

[0057] 2) Plasma surface treatment of hollow ceramic microspheres: Three jet heads are installed in the center of the drum to spray plasma onto the surrounding drum walls. The hollow ceramic microspheres are loaded into the drum, the rotation speed is 2000 rpm, the plasma composition is nitrogen (N2), the power is 200W, and the treatment time is 15 minutes.

[0058] 3) Preparation of double-layer PVDF-coated titanium dioxide: Preparation of modified titanium dioxide powder: Prepare 7000g of 5wt% tridecafluorooctyltriethoxysilane aqueous solution, heat to 60℃, stir at 1500rpm, add 70g of Triton-100, stir for 5 minutes, then add 1000g of titanium dioxide powder with D50=6um in 3 batches, with an interval of 10 minutes between each addition. After the powder is added, continue stirring for 30 minutes, stop heating, allow to cool naturally, pour the liquid into a spray drying device for spray drying, collect the powder, and obtain modified titanium dioxide powder.

[0059] Preparation of the inner PVDF layer: 20 g PVDF (Mw≈440 kDa) and 0.1 g polyvinylpyrrolidone (PVP) were dissolved in 97 g DMF and stirred at 50 °C until clear. 100 g modified titanium dioxide powder was added and dispersed by high-speed shearing (8000 rpm, 5 min). The resulting slurry was added dropwise at 1 mL / min to 10 times its volume of deionized water (55 °C, stirring at 600 rpm). Stirring was continued for 30 min, followed by centrifugation (4000 rpm, 10 min), washing twice with deionized water and twice with ethanol, and vacuum drying at 60 °C for 1 h to obtain a single layer of PVDF-coated titanium dioxide.

[0060] Preparation of the outer PVDF layer: 15 g PVDF (Mw≈440 kDa) and 0.1 g polyvinylpyrrolidone (PVP) were dissolved in 97 g DMF and stirred at 50 °C until clear. 100 g of monolayer PVDF-coated titanium dioxide was added and dispersed by high-speed shearing (8000 rpm, 5 min). The resulting slurry was added dropwise at 1 mL / min to 10 times its volume of deionized water (55 °C, stirring at 600 rpm). Stirring was continued for 30 min, followed by centrifugation (4000 rpm, 10 min), washing twice with deionized water and twice with ethanol, and vacuum drying at 60 °C for 2 h to obtain a double-layer PVDF-coated titanium dioxide.

[0061] 4) Continuous dry molding: All raw materials are added to a high-speed shear mixer according to the specified ratio and mixed at 4500 rpm for 90 seconds until a dough-like consistency is formed. The dough-like product is cut into small pieces and fed into the screw extruder feeding system, which is heated to 60°C. The screw extruder die is selected with a width of 224 mm. After extrusion, a sheet-like thermal insulation composite material with a thickness of 2 mm is obtained.

[0062] Figure 1 The image shows a scanning electron microscope (SEM) image of the thermal insulation composite material prepared in Example 2 (scale bar 100 μm). Figure 2 The image shows a scanning electron microscope (SEM) image (scale bar 10 μm) of the thermal insulation composite material prepared in Example 2.

[0063] The properties of the thermal insulation composite materials obtained in Examples 1-3 and Comparative Examples 1-3 are shown in Table 2.

[0064] Table 2 As shown in Table 2, the thermal conductivity of the resulting thermal insulation composite material increases with the increasing content of the double-layer PVDF-coated titanium dioxide. However, when the content reaches 7.5 wt%, the high thermal conductivity leads to poor insulation performance. Simultaneously, the tensile strength and compressive resilience of the resulting thermal insulation composite material gradually increase with the increasing content of the double-layer PVDF-coated titanium dioxide. Therefore, considering all three indicators, controlling the content of the double-layer PVDF-coated titanium dioxide between 1.5 and 5.5 wt% yields the best results.

[0065] (II) Effects of titanium dioxide, single-layer PVDF-coated titanium dioxide, and double-layer PVDF-coated titanium dioxide on the performance of thermal insulation composite materials Comparative Example 4 The difference from Example 2 is that titanium dioxide is used instead of double-layer PVDF-coated titanium dioxide. The preparation method of its thermal insulation composite material includes the following steps: 1) Surface modification of hydrophobic SiO2 particles: Prepare 70 kg of 5 wt% KH-560 aqueous solution, heat to 60℃, stir at 1500 rpm, add 10 kg of SiO2 particles to the stirring liquid in 3 batches, with an interval of 10 minutes between each addition. After the SiO2 particles are added, continue stirring for 30 minutes and then stop heating. Allow to cool naturally, pour the liquid into a spray drying equipment for spray drying, collect the powder, and obtain hydrophobic SiO2 particles.

[0066] 2) Plasma surface treatment of hollow ceramic microspheres: Three jet heads are installed in the center of the drum to spray plasma onto the surrounding drum walls. The hollow ceramic microspheres are loaded into the drum, the rotation speed is 2000 rpm, the plasma composition is nitrogen (N2), the power is 200W, and the treatment time is 15 minutes.

[0067] 3) Continuous dry molding: All raw materials are added to a high-speed shear mixer according to the specified ratio and mixed at 4500 rpm for 90 seconds until a dough-like consistency is formed. The dough-like product is cut into small pieces and fed into the screw extruder feeding system, which is heated to 60°C. The screw extruder die is selected with a width of 224 mm. After extrusion, a sheet-like thermal insulation composite material with a thickness of 2 mm is obtained.

[0068] Comparative Example 5 The difference from Example 2 is that a single layer of PVDF-coated titanium dioxide is used instead of a double layer of PVDF-coated titanium dioxide. The preparation method of its thermal insulation composite material includes the following steps: 1) Surface modification of hydrophobic SiO2 particles: Prepare 70 kg of 5 wt% KH-560 aqueous solution, heat to 60℃, stir at 1500 rpm, add 10 kg of SiO2 particles to the stirring liquid in 3 batches, with an interval of 10 minutes between each addition. After the SiO2 particles are added, continue stirring for 30 minutes and then stop heating. Allow to cool naturally, pour the liquid into a spray drying equipment for spray drying, collect the powder, and obtain hydrophobic SiO2 particles.

[0069] 2) Plasma surface treatment of hollow ceramic microspheres: Three jet heads are installed in the center of the drum to spray plasma onto the surrounding drum walls. The hollow ceramic microspheres are loaded into the drum, the rotation speed is 2000 rpm, the plasma composition is nitrogen (N2), the power is 200W, and the treatment time is 15 minutes.

[0070] 3) Preparation of single-layer PVDF-coated titanium dioxide: Preparation of modified titanium dioxide powder: Prepare 7000g of 5wt% tridecafluorooctyltriethoxysilane aqueous solution, heat to 60℃, stir at 1500rpm, add 70g of Triton-100, stir for 5 minutes, then add 1000g of titanium dioxide powder with D50=6um in 3 batches, with an interval of 10 minutes between each addition. After the powder is added, continue stirring for 30 minutes, stop heating, allow to cool naturally, pour the liquid into a spray drying device for spray drying, collect the powder, and obtain modified titanium dioxide powder.

[0071] Preparation of monolayer PVDF-coated titanium dioxide: 20 g PVDF (Mw≈440 kDa) and 0.1 g polyvinylpyrrolidone (PVP) were dissolved in 97 g DMF and stirred at 50 °C until clear. 100 g modified titanium dioxide powder was added and dispersed by high-speed shearing (8000 rpm, 5 min). The resulting slurry was added dropwise at 1 mL / min to 10 times its volume of deionized water (55 °C, stirring at 600 rpm). Stirring was continued for 30 min, followed by centrifugation (4000 rpm, 10 min), washing twice with deionized water and twice with ethanol, and vacuum drying at 60 °C for 1 h to obtain monolayer PVDF-coated titanium dioxide.

[0072] 4) Continuous dry molding: All raw materials are added to a high-speed shear mixer according to the specified ratio and mixed at 4500 rpm for 90 seconds until a dough-like consistency is formed. The dough-like product is cut into small pieces and fed into the screw extruder feeding system, which is heated to 60°C. The screw extruder die is selected with a width of 224 mm. After extrusion, a sheet-like thermal insulation composite material with a thickness of 2 mm is obtained.

[0073] The properties of the thermal insulation composite materials obtained in Example 2 and Comparative Examples 4-5 are shown in Table 3.

[0074] Table 3 As can be seen from the data comparison in Table 3, in Comparative Examples 4 and 5, after replacing the double-layer PVDF-coated titanium dioxide with titanium dioxide and single-layer PVDF-coated titanium dioxide respectively, the data of tensile strength and compressive resilience both showed a significant decrease.

[0075] (III) Effect of different PP fiber contents on the performance of thermal insulation composite materials The formulations of Examples 2 / 4-5 and Comparative Examples 6-8 are shown in Table 5: Table 5 The properties of the thermal insulation composite materials obtained in Examples 2, 4-5 and Comparative Examples 6-8 are shown in Table 6.

[0076] Table 6 As shown in Table 6, the tensile strength and compressive resilience of the resulting thermal insulation composite material gradually increase with increasing PP fiber content. When the PP fiber content is below 1 wt%, the tensile strength and compressive resilience of the thermal insulation composite material are poor. Simultaneously, the thermal conductivity of the resulting thermal insulation composite material shows an upward trend with increasing PP fiber content. When the PP fiber content reaches 9 wt%, the thermal conductivity is too high, making it difficult to meet the thermal insulation requirements of the composite material. Considering all three indicators, controlling the PP fiber content between 3-7 wt% yields the best results.

[0077] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A continuous dry-molded thermal insulation composite material, characterized in that... Including the following raw materials: 20-55 wt% glass fiber 5-10 wt% basalt fiber PP fiber 3-7wt%, 15-25 wt% hydrophobic SiO2 particles Hollow ceramic microspheres 7-16.5 wt%, Powder binder 1.5-5.5 wt%; The powder binder is a double-layer PVDF-coated titanium dioxide.

2. The continuous dry-molded thermal insulation composite material according to claim 1, characterized in that: The particle size D50 of the double-layer PVDF-coated titanium dioxide is 10-15 μm; The thickness of the inner PVDF layer is 2.5-3.5 μm, and the thickness of the outer PVDF layer is 1-2 μm.

3. The continuous dry-molded thermal insulation composite material according to claim 1, characterized in that: The basalt fiber has a diameter of 7-9 μm and a tensile strength ≥2500 MPa after heat treatment at 650℃. The glass fiber has a diameter of 2-4 μm, a SiO2 content of ≥96wt%, and a softening point of ≥1650℃; The diameter of the PP fiber is 3-8 μm; The hydrophobic SiO2 particles have a D50 of 0.01-0.03 μm and a specific surface area of ​​300-500 m². 2 / g; the wall thickness / diameter ratio of the hollow ceramic microspheres is 1:15-25.

4. The continuous dry-molded thermal insulation composite material according to any one of claims 1-3, characterized in that: The hydrophobic SiO2 particles are SiO2 particles that have been surface modified with a silane coupling agent. The preparation method includes: heating an aqueous solution containing 3-7 wt% silane coupling agent to 55-65°C, adding SiO2 particles in batches under stirring, and spray-drying the resulting liquid to obtain hydrophobic SiO2 particles.

5. The continuous dry-molded thermal insulation composite material according to any one of claims 1-3, characterized in that: The hollow ceramic microspheres undergo plasma surface treatment under the following conditions: nitrogen plasma is used, with a power of 15-250W and a time of 10-20min.

6. A method for preparing a continuous dry-molded thermal insulation composite material according to any one of claims 1-5, characterized in that... include: 1) Titanium dioxide powder was surface-treated with tridecafluorooctyltriethoxysilane and spray-dried to obtain modified titanium dioxide powder; Modified titanium dioxide powder was dispersed in a solvent containing PVDF, and the resulting slurry was dropped into water under heating and stirring. After post-treatment, an inner layer of PVDF-coated titanium dioxide was obtained. The inner layer of PVDF-coated titanium dioxide was dispersed in a solvent containing PVDF, and the resulting slurry was dropped into water under heating and stirring. After post-treatment, a double layer of PVDF-coated titanium dioxide was obtained. 2) Mix all raw materials into a dough-like consistency, and then process and extrude the dough using a screw extruder to obtain sheet-like heat-insulating composite material.

7. The preparation method according to claim 6, characterized in that: In step 1), The solvent is N,N-dimethylformamide or N-methylpyrrolidone; During the first addition, the concentration of PVDF in the solvent containing PVDF was 15-20 wt%; during the second addition, the concentration of PVDF in the solvent containing PVDF was 10-14 wt%. The solvent containing PVDF also contains: 0.05-0.15 wt% polyvinylpyrrolidone or 0.03-0.07 wt% sodium dodecyl sulfate.

8. The preparation method according to claim 6 or 7, characterized in that: In step 1), The dripping rate of the slurry is 0.8-1.2 mL / min; The mass ratio of the slurry to water is 1:8-12.

9. The preparation method according to claim 6, characterized in that: In step 2), the die width of the screw extruder is >200mm and the thickness is 1-3mm.

10. The application of the continuous dry-molded thermal insulation composite material according to any one of claims 1-5 or the continuous dry-molded thermal insulation composite material obtained by the preparation method according to any one of claims 6-9 as a battery thermal insulation sheet.

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