High-performance PVC (polyvinyl chloride) composite board and preparation process thereof

Abstract

The invention discloses a high-performance PVC composite board and a preparation process thereof.The high-performance PVC composite board is composed of PVC resin, nano boehmite, amino-modified nano silicon dioxide, a silane coupling agent KH560, an acrylate impact modifier ACR and the like, the bottleneck of synergistic interaction among the components is broken through, a multi-layer functional network is constructed, and the high-performance PVC composite board is prepared. Finally, the PVC composite board is greatly improved in the aspects of heat insulation, flame retardance, aging resistance, mechanical properties and the like, and the performance of the composite board is comprehensively improved.

Description

Technical Field

[0001] This invention relates to the field of PVC composite board production technology, specifically to a high-performance PVC composite board and its preparation process. Background Technology

[0002] In the fields of architectural decoration, outdoor facilities, and home building materials, PVC composite panels are widely used due to their lightweight, ease of processing, and low cost, such as exterior wall panels, outdoor leisure tables and chairs, and interior partitions. However, while traditional PVC panels have advantages such as lightweight and corrosion resistance, their inherent shortcomings—poor flame retardancy, poor weather resistance, and insufficient mechanical strength—severely restrict their application in key scenarios such as high-end exterior wall panels and fireproof partitions. Especially with the continuous improvement of green building standards, there is an urgent need to develop new PVC-based composite materials that combine efficient heat insulation, self-flame retardancy, aging resistance, and high strength and toughness. Existing modification technologies often focus on improving a single performance metric, such as adding flame retardants to enhance the flame retardancy of the board. However, simply adding flame retardants often damages the mechanical properties of the board. Similarly, adding large amounts of UV absorbers or light stabilizers to improve weather resistance, while delaying aging, fails to significantly improve the mechanical strength of the material itself and may even introduce migration and precipitation problems. Conversely, filling large amounts of calcium carbonate or toughening agents to enhance mechanical properties, while improving the rigidity and toughness of the board, may significantly degrade its flame retardancy and thermal stability. These technical solutions struggle to achieve synergistic optimization of multi-dimensional performance and cannot meet the comprehensive service capabilities required by complex and demanding operating conditions. Therefore, overcoming the bottleneck of synergistic effects between components and constructing a multi-layered functional network has become the core challenge in developing next-generation high-performance PVC composite boards. Summary of the Invention

[0003] To address the aforementioned challenges, one objective of this application is to provide a high-performance PVC composite board, comprising the following components by weight: 45-65 parts PVC resin, 21-29 parts calcium carbonate, 1-3 parts PE wax, 2-4 parts stearic acid, 6-8 parts nano-boehmite, 3-7 parts amino-modified nano-silica, 0.5-1.5 parts silane coupling agent KH560, and 1.5-2.5 parts acrylate impact modifier ACR.

[0004] Another objective of this application is to provide a process for preparing high-performance PVC composite panels, characterized by comprising the following steps: Preparation of amino-modified nano-silica; To obtain mixture a: Mix 45-65 parts of PVC resin, 21-29 parts of calcium carbonate, 1-3 parts of PE wax, 2-4 parts of stearic acid, 3-7 parts of amino-modified nano-silica, 0.5-1.5 parts of silane coupling agent KH560 and 1.5-2.5 parts of acrylate impact modifier ACR are mixed evenly according to the mass ratio to obtain mixture a; To obtain mixture b: Add 6-8 parts of nano-boehmite to mixture a by atomization spraying to obtain mixture b; Mixture b is fed into a twin-screw extruder; then the twin-screw extruder is heated to melt mixture b, which is then extruded and pressed, cooled and shaped to obtain the finished product.

[0005] Preferably, the preparation of amino-modified nano-silica includes the following steps: according to the mass fraction, 15-25 parts of tetraethyl orthosilicate and 55-75 parts of anhydrous ethanol are mixed, ultrasonically dispersed for 25-35 min, 6-10 parts of water are added, and hydrolysis reaction is carried out for 1-2 h under high-speed magnetic stirring, then 3-7 parts of ammonia are added, and the reaction is continued for 3-4 h, then 1-3 parts of APTES are added, and the reaction is heated and stirred at 55-65℃ for 3-4 h, and dried to obtain the amino-modified nano-silica.

[0006] Preferably, obtaining mixture b specifically includes the following steps: transferring mixture a to a mixing tank equipped with a high-efficiency atomizing spray system, stirring mixture a at 100-300 rpm / min, loading 6-8 parts of nano-boehmite into the hopper of the spray system, starting the atomizing spray system, adjusting the nozzle pressure to 0.3-0.5 MPa, and the atomized particle size to 30-50 μm, uniformly spraying the nano-boehmite onto the agitated mixture a at a constant rate, and continuing to stir for 3-5 minutes after spraying to obtain mixture b. Using a high-temperature, high-shear mixing method can cause the nano-boehmite to agglomerate and damage its properties. Atomizing spraying and low-speed stirring ensure that the sprayed nano-boehmite is uniformly dispersed in mixture a in an extremely fine particle state, which not only greatly protects the nano-boehmite but also ensures a high degree of consistency in the quality of the composite board, significantly improving its flame retardancy and aging resistance.

[0007] Preferably, the temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 110~120℃; Zone 2: 120~130℃; Zone 3: 130~140℃; Zone 4: 145~155℃; Zone 5: 155~165℃; Zone 6: 165~175℃; Zone 7: 180~190℃; and the die temperature: 205~215℃. This reasonable extrusion temperature gradient ensures the gradual melting and plasticization of the PVC resin, avoiding localized overheating that could lead to resin decomposition or insufficient melting due to excessively low temperatures.

[0008] Preferably, the cooling and shaping process employs a gradient cooling method, using an airflow with a wind speed of 10~15m / s and a cooling rate of 10~15℃ / min for ventilation cooling. The gradient cooling method can effectively reduce the internal stress generated during the cooling process, prevent the board from warping and deforming, and control the wind speed and cooling rate can avoid cracks or spots caused by uneven surface cooling.

[0009] Preferably, before feeding mixture b into the twin-screw extruder, it is first subjected to vacuum degassing treatment at a vacuum degree of -0.06 to -0.08 MPa for a treatment time of 5 to 10 minutes. Vacuum degassing promptly removes water vapor generated during the dehydration of nano-boehmite and volatiles generated by other components, resulting in a denser structure and better mechanical properties in the finished product.

[0010] Preferably, the screw speed of the twin-screw extruder is 200~300 r / min. If the speed is too low, the shear force is insufficient, and the PVC resin cannot be completely melted and plasticized. If the speed is too high, the frictional shear heat will increase sharply, causing some PVC resin to decompose and destroying the nano-boehmite. A suitable screw speed is beneficial to improving the mechanical properties, flame retardancy, and aging resistance of the composite board.

[0011] The beneficial effects are as follows: This application achieves comprehensive performance improvement of the composite board by constructing a multi-level synergistic network through various components. In terms of flame retardancy, γ-Al2O3 particles generated by the stepwise dehydration of nano-boehmite are embedded in PVC resin to form a heat-reflective network, reducing the thermal conductivity of the composite board to 0.12 W / (m·K). In addition, when the composite board burns at high temperatures, the γ-Al2O3 particles can form a Si-O-Al cross-linked structure with the silane coupling agent KH-560 and construct a three-dimensional network structure with amino-modified nano-silica, achieving rapid ceramicization to block heat transfer. In terms of aging resistance, the amino-modified nano-silica, after being bridged by KH-560, forms a Si-OC three-dimensional network with PVC to block the photo-oxidation chain reaction. At the same time, the γ-Al2O3 particles generated by the dehydration of nano-boehmite are anchored in the three-dimensional network to form an ultraviolet reflective layer. The two work synergistically. This process significantly improves the aging resistance of the composite board. Regarding mechanical properties, firstly, the silane coupling agent KH-560 improves the compatibility of amino-modified nano-silica with PVC resin, significantly enhancing the dispersibility of nanoparticles in the system. Then, the aforementioned components are used to construct a three-dimensional network, improving the structural stability of the composite board. Simultaneously, components such as calcium carbonate and amino-modified nano-silica are anchored within the three-dimensional network to enhance its rigidity. Furthermore, KH-560 bridges the carboxyl group reaction between nano-SiO2 and ACR, forming a rigid core and flexible shell interface structure. This results in a flexural strength exceeding 90 MPa and a tensile strength exceeding 75 MPa for the composite board. Finally, the combination of atomized spraying technology and multi-stage temperature-controlled extrusion ensures uniform dispersion of components, stepwise dehydration, and synchronous network construction, ultimately achieving efficient synergy in the PVC composite board's thermal insulation, flame retardancy, aging resistance, and mechanical properties. Detailed Implementation

[0012] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0013] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the specific embodiments of the invention without inventive effort are within the protection scope of the invention.

[0014] In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0015] Raw material source: Polyvinyl chloride (PVC) resin, models SG-3, SG-5, and SG-8, were purchased from Wuhan Jiyesheng Chemical Co., Ltd. Calcium carbonate, purchased from Hebei Maikemaini Mineral Products Co., Ltd. Polyethylene wax (PE wax) was purchased from Hubei Qibajiu Chemical Co., Ltd. Stearic acid, purchased from Guangzhou Aobosheng Chemical Co., Ltd.; Nano-boehmite (γ-AlOOH), purchased from Xuancheng Jingrui New Materials Co., Ltd.; Acrylic ester impact modifier ACR was purchased from Shandong Shangguan New Material Technology Co., Ltd. Silane coupling agent KH560 was purchased from Shandong Yuanjin New Materials Co., Ltd. Tetraethyl orthosilicate (TEOS), Shanghai Runjie Chemical Reagent Co., Ltd.; Ammonia solution, with a mass fraction of 25%~28%, was purchased from Xilong Scientific Co., Ltd. Anhydrous ethanol, purity 99.7%, analytical grade, purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd. 3-Aminopropyltriethoxysilane (APTES), purchased from Sinopharm Chemical Reagent Co., Ltd. Tetraethyl orthosilicate, purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd. All other reagents were commercially available.

[0016] Example 1 A process for preparing high-performance PVC composite boards includes the following steps: Preparation of amino-modified nano-silica: 25 parts by mass of tetraethyl orthosilicate and 55 parts by anhydrous ethanol were mixed and ultrasonically dispersed for 25 min. 10 parts by mass of water were added and hydrolyzed for 1 h under high-speed magnetic stirring. Then 7 parts by mass of ammonia were added and the reaction was continued for 3 h. Then 3 parts by mass of APTES were added and the reaction was heated and stirred at 55 °C for 3 h. The mixture was then dried to obtain amino-modified nano-silica. To obtain mixture a: Mix 45 parts PVC resin, 29 parts calcium carbonate, 3 parts PE wax, 4 parts stearic acid, 7 parts amino-modified nano silica, 1.5 parts silane coupling agent KH560 and 2.5 parts acrylate impact modifier ACR are mixed evenly according to the mass ratio to obtain mixture a. To obtain mixture b: Transfer mixture a to a mixing tank equipped with a high-efficiency atomizing spray system. Stir mixture a at 100 rpm / min. Load 8 parts of nano-boehmite into the hopper of the spray system. Start the atomizing spray system, adjust the nozzle pressure to 0.3 MPa, and the atomized particle size to 30 μm. Spray the nano-boehmite evenly onto the agitated mixture a at a constant rate. After spraying is complete, continue stirring for 3 minutes to obtain mixture b. Transfer mixture b to a vacuum degassing device, start the vacuum pump, and perform vacuum degassing treatment on it. Evacuate to the set vacuum level of -0.06MPa and maintain it for 5 minutes. Slight vibration can be applied during the degassing process to improve the degassing efficiency. The vacuum-degassed mixture b is fed into a twin-screw extruder; then the twin-screw extruder is heated to melt the mixture b, which is then extruded by the twin-screw extruder and pressed, cooled and shaped to obtain the finished product; The twin-screw extruder has a screw speed of 200 r / min and the temperatures of each zone are as follows: Zone 1: 110℃, Zone 2: 120℃, Zone 3: 130℃, Zone 4: 145℃, Zone 5: 155℃, Zone 6: 165℃, Zone 7: 180℃, and the die temperature is 205℃. The cooling and shaping process adopts a gradient cooling method, with an airflow of 10 m / s and a cooling rate of 10℃ / min.

[0017] Example 2 A process for preparing high-performance PVC composite boards includes the following steps: Preparation of amino-modified nano-silica: 20 parts by mass of tetraethyl orthosilicate and 65 parts by anhydrous ethanol were mixed and ultrasonically dispersed for 30 min. 8 parts by mass of water were added and hydrolyzed for 1.5 h under high-speed magnetic stirring. 5 parts by mass of ammonia were added and the reaction continued for 3.5 h. 2 parts by mass of APTES were added and the mixture was heated and stirred at 60 °C for 3.5 h. The mixture was then dried to obtain amino-modified nano-silica. Mixture a is obtained by mixing 55 parts PVC resin, 25 parts calcium carbonate, 2 parts PE wax, 3 parts stearic acid, 5 parts amino-modified nano silica, 1 part silane coupling agent KH560 and 2 parts acrylate impact modifier ACR in proportion to mass. To obtain mixture b: Transfer mixture a to a mixing tank equipped with a high-efficiency atomizing spray system. Stir mixture a at 200 rpm / min. Load 7 parts of nano-boehmite into the hopper of the spray system. Start the atomizing spray system, adjust the nozzle pressure to 0.4 MPa, and the atomized particle size to 40 μm. Spray the nano-boehmite evenly onto the agitated mixture a at a constant rate. After spraying is complete, continue stirring for 4 minutes to obtain mixture b. Transfer mixture b to a vacuum degassing device, start the vacuum pump, and perform vacuum degassing treatment on it. Evacuate to the set vacuum level of -0.07MPa and maintain it for 8 minutes. Slight vibration can be applied during the degassing process to improve the degassing efficiency. The vacuum-degassed mixture b is fed into a twin-screw extruder; then the twin-screw extruder is heated to melt the mixture b, which is then extruded by the twin-screw extruder and pressed, cooled and shaped to obtain the finished product; The twin-screw extruder has a screw speed of 250 r / min and the temperatures of each zone are as follows: Zone 1: 115℃, Zone 2: 125℃, Zone 3: 135℃, Zone 4: 150℃, Zone 5: 160℃, Zone 6: 170℃, Zone 7: 185℃, and the die temperature is 210℃. The cooling and shaping process adopts a gradient cooling method, with an airflow of 13 m / s and a cooling rate of 13℃ / min.

[0018] Example 3 A process for preparing high-performance PVC composite boards includes the following steps: Preparation of amino-modified nano-silica: 15 parts by mass of tetraethyl orthosilicate and 75 parts by anhydrous ethanol were mixed and ultrasonically dispersed for 35 min. 6 parts by mass of water were added and hydrolyzed for 2 h under high-speed magnetic stirring. 3 parts by mass of ammonia were added and the reaction continued for 4 h. 1 part by mass of APTES was added and the reaction was heated and stirred at 65 °C for 4 h. The mixture was then dried to obtain amino-modified nano-silica. To obtain mixture a: Mix 65 parts PVC resin, 21 parts calcium carbonate, 1 part PE wax, 2 parts stearic acid, 3 parts amino-modified nano silica, 0.5 parts silane coupling agent KH560 and 1.5 parts acrylate impact modifier ACR are mixed evenly according to the mass ratio to obtain mixture a. To obtain mixture b: Transfer mixture a to a mixing tank equipped with a high-efficiency atomizing spray system. Stir mixture a at 300 rpm / min. Load 6 parts of nano-boehmite into the hopper of the spray system. Start the atomizing spray system, adjust the nozzle pressure to 0.5 MPa, and the atomized particle size to 50 μm. Spray the nano-boehmite evenly onto the agitated mixture a at a constant rate. After spraying is complete, continue stirring for 5 minutes to obtain mixture b. Transfer mixture b to a vacuum degassing device, start the vacuum pump, and perform vacuum degassing treatment on it. Evacuate to the set vacuum level of -0.08MPa and maintain it for 10 minutes. Slight vibration can be applied during the degassing process to improve the degassing efficiency. The vacuum-degassed mixture b is fed into a twin-screw extruder; then the twin-screw extruder is heated to melt the mixture b, which is then extruded by the twin-screw extruder and pressed, cooled and shaped to obtain the finished product; The twin-screw extruder has a screw speed of 300 r / min and the temperatures of each zone are as follows: Zone 1: 120℃, Zone 2: 130℃, Zone 3: 140℃, Zone 4: 155℃, Zone 5: 165℃, Zone 6: 175℃, Zone 7: 190℃, and the die temperature is 215℃. The cooling and shaping process adopts a gradient cooling method, with an airflow of 15 m / s and a cooling rate of 15℃ / min.

[0019] Comparative Example 1 The difference between this comparative example and Example 2 is that 1 part of silane coupling agent KH550 is replaced with 1 part of silane coupling agent KH560 in Example 2. All other components and experimental procedures are the same as in Example 2.

[0020] Comparative Example 2 The difference between this comparative example and Example 2 is that 7 parts of aluminum hydroxide were used to replace 7 parts of nano-boehmite in Example 2, while the other components and experimental procedures were the same as in Example 2.

[0021] Comparative Example 3 The difference between this comparative example and Example 2 is that 5 parts of nano-silica were replaced with 5 parts of amino-modified nano-silica in Example 2, while the other components and experimental steps were the same as in Example 2.

[0022] Comparative Example 4 The difference between this comparative example and Example 2 is that, instead of using an atomized spray method to add 6-8 parts of nano-boehmite to mixture a to obtain mixture b, 6-8 parts of nano-boehmite were directly stirred with mixture a to obtain mixture b.

[0023] Comparative Example 5 The difference between this comparative example and Example 2 is that the temperature of each zone of the twin-screw extruder and the die temperature are maintained at 230°C.

[0024] The composite plate samples obtained in Examples 1-3 and Comparative Examples 1-5 were tested.

[0025] Test method: The bending strength test method shall be carried out in accordance with GB / T142082-2009 using a universal testing machine; The tensile strength test method shall be performed using a universal testing machine in accordance with GB / T 1040.1-2006; The aging resistance test method was conducted according to GB / T16422.2-2014 "Laboratory Light Source Exposure Test Methods for Plastics - Part 2: Xenon Arc Lamp". Artificial aging tests were performed on each sample using a UV2000 fluorescent ultraviolet aging test chamber (UVB-313 lamp tube), with a test irradiance of 0.55 W / m². 2 The tensile properties of the sample were determined at 340 nm, 50 °C, and for 7 days. The thermal conductivity was tested according to GB / T3399-2022 "Test Method for Thermal Conductivity of Plastics - Transient Plane Heat Source Method"; The flame retardancy test method is in accordance with UL94 standard; The static elimination performance test method is conducted in accordance with the national standard "Electrostatics Part 2-3: Test Methods for Resistance and Resistivity of Antistatic Solid Planar Materials"; Table 1. Performance Test Results of Diffuser Plate

[0026] As shown in Table 1, the flexural strength of each embodiment of this application reaches over 90 MPa, the tensile strength reaches 75 MPa, and the tensile strength remains above 70 MPa after aging. The thermal conductivity decreases to below 0.15, the flame retardancy reaches V0 level, and the surface resistivity decreases to 10. 8 Ω / sq, wherein Example 2 is slightly better than Example 1 and Example 3; Further comparative analysis of the data from Example 1 and the five comparative examples revealed that in Comparative Example 1, replacing silane coupling agent KH560 with silane coupling agent KH550 significantly reduced the flame retardancy and mechanical properties of the composite board. This may be because although the amino group of KH-550 can improve the interfacial compatibility between nanoparticles and PVC, it lacks epoxy groups, thus failing to achieve covalent bonding with ACR and unable to form Si-O-Al ceramic barrier with γ-Al2O3 particles at high temperatures, resulting in a significant decrease in the flame retardancy of the composite board. Furthermore, KH-550 lacks methacryloyloxy and siloxane groups, meaning it cannot undergo free radical copolymerization with the carboxyl groups in ACR, nor can it undergo condensation reaction with the hydroxyl groups on the surface of amino-modified nano-silica to form a rigid core with ACR as the flexible core. The composite interface of the shell is reinforced, which leads to a significant decrease in the mechanical properties of the composite board. In Comparative Example 2, after replacing nano-boehmite with aluminum hydroxide, the flame retardancy and mechanical properties of the composite board decreased. This may be because aluminum hydroxide has a low decomposition temperature and will decompose into the final product α-Al2O3 in large quantities in the processing temperature range of the twin-screw extruder. In contrast, nano-boehmite has a relatively high decomposition temperature and can dehydrate stepwise to generate γ-Al2O3 particles with high specific surface area and mesoporous structure. Due to the large difference in particle structure between α-Al2O3 and γ-Al2O3, the heat reflection effect of α-Al2O3 is far inferior to that of γ-Al2O3. Furthermore, α-Al2O3 is difficult to effectively form the key Si-O-Al cross-linking structure with other components and rapidly ceramize under high temperature conditions, thus resulting in a decrease in the heat insulation and flame retardant properties of the composite board.Furthermore, the abundant hydroxyl groups on the surface of γ-Al₂O₃ particles facilitate the reaction with the silane coupling agent KH560 to form strong bonds, thereby constructing a more stable three-dimensional network with amino-modified nano-silica. In contrast, the surface of α-Al₂O₃, due to its high crystallinity and low surface activity, has a relatively small number of surface hydroxyl groups, making it difficult to form a stable three-dimensional network, leading to a decline in the mechanical properties of the composite board and poor aging resistance. In Comparative Example 3, after replacing amino-modified nano-silica with nano-silica, the mechanical properties of the composite board deteriorated and it became less resistant to aging. This may be because the surface of nano-silica has a large number of hydrophilic silanol groups (-Si-OH), which have poor compatibility with hydrophobic polymers such as PVC. The presence of agglomerates in nano-silica leads to uneven dispersion within the matrix, thus reducing the mechanical properties of the composite board. Amino-modified nano-silica, by introducing -NH2 functional groups, allows for chemical reactions with PVC and the silane coupling agent KH-560, significantly improving the compatibility and interfacial bonding between nanoparticles and the polymer matrix. Furthermore, due to the lack of -NH2 functional groups, nano-silica's bonding strength with components such as the silane coupling agent KH-560 and ACR is far less than that of amino-modified nano-silica, failing to form a more stable three-dimensional network. The γ-Al2O3 particles generated from the dehydration of nano-boehmite also cannot stably anchor within this three-dimensional network to form a complete ultraviolet reflective layer, resulting in compromised composite properties. The aging resistance of the board deteriorated. In Comparative Example 4, instead of using atomized spraying to add 6-8 parts of nano-boehmite to mixture a to obtain mixture b, 6-8 parts of nano-boehmite were directly stirred with mixture a to obtain mixture b. This resulted in a decrease in both the flame retardant and mechanical properties of the composite board. This may be because nano-boehmite has a high specific surface area and surface energy, making it prone to local agglomeration during conventional stirring. If the boehmite is unevenly distributed, the γ-Al2O3 particles cannot be uniformly embedded in the PVC matrix to form a continuous and effective heat reflective layer, leading to an increase in the thermal conductivity of the composite board and a decrease in flame retardant performance. At the same time, due to the uneven distribution of nano-boehmite, it cannot react with KH-560 and amino-modified sodium... The stable and uniform three-dimensional network structure constructed by components such as silica and ACR leads to a decrease in the mechanical properties of the composite board. In Comparative Example 5, the temperature of each zone and the die head of the twin-screw extruder were maintained at 230℃, resulting in a decrease in the mechanical properties of the composite board, poor heat insulation and flame retardancy, and poor aging resistance. This may be because the extrusion temperature was maintained at 230℃ for a long time, causing the components to mix at high temperature for a long time, which led to the premature decomposition of PVC resin, destruction of the structure of components such as coupling agent KH560 and ACR, and inability to effectively construct a three-dimensional network structure. The photo-oxidation chain reaction was difficult to block, the dehydration of nano-boehmite was incomplete, and γ-Al2O3 particles could not be uniformly anchored in the three-dimensional network, resulting in the inability to form a complete ultraviolet reflective layer.

[0027] In summary, this application achieves comprehensive performance enhancement of the composite board by constructing a multi-level synergistic network among its components. Regarding flame retardancy, γ-Al₂O₃ particles generated from the stepwise dehydration of nano-boehmite are embedded in the PVC resin to form a heat-reflective network, reducing the thermal conductivity of the composite board to 0.12 W / (m·K). Furthermore, when the composite board burns at high temperatures, the γ-Al₂O₃ particles can form a Si-O-Al cross-linked structure with the silane coupling agent KH-560 and construct a three-dimensional network structure with amino-modified nano-silica, achieving rapid ceramicization to block heat transfer. Regarding aging resistance, amino-modified nano-silica, bridged by KH-560, forms a Si-OC three-dimensional network with PVC to block the photo-oxidation chain reaction. Simultaneously, γ-Al₂O₃ particles generated from the dehydration of nano-boehmite are anchored in the three-dimensional network to form an ultraviolet reflective layer. The synergistic effect of these two processes significantly improves the overall performance of the composite board. To improve the aging resistance of composite panels, in terms of mechanical properties, the silane coupling agent KH-560 is first used to improve the compatibility of amino-modified nano-silica with PVC resin, significantly enhancing the dispersibility of nanoparticles in the system. Then, the above components are used to construct a three-dimensional network to improve the structural stability of the composite panel. At the same time, components such as calcium carbonate and amino-modified nano-silica are anchored in the three-dimensional network to enhance its rigidity. KH-560 also bridges the carboxyl reaction between nano-SiO2 and ACR to form a rigid core and flexible shell interface structure, thus enabling the composite panel to achieve a bending strength of over 90 MPa and a tensile strength of over 75 MPa. Furthermore, the combination of atomized spraying process and multi-stage temperature-controlled extrusion ensures uniform dispersion of each component, stepwise dehydration, and synchronous network construction, ultimately achieving efficient synergy in the PVC composite panel in terms of heat insulation, flame retardancy, aging resistance, and mechanical properties.

[0028] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A high-performance PVC composite board, characterized in that, The product is composed of the following components by weight: 45-65 parts PVC resin, 21-29 parts calcium carbonate, 1-3 parts PE wax, 2-4 parts stearic acid, 6-8 parts nano boehmite, 3-7 parts amino-modified nano silica, 0.5-1.5 parts silane coupling agent KH560 and 1.5-2.5 parts acrylate impact modifier ACR.

2. A process for preparing a high-performance PVC composite board as described in claim 1, characterized in that, Includes the following steps: Preparation of amino-modified nano-silica; To obtain mixture a: Mixture a is prepared by uniformly mixing 45-65 parts of PVC resin, 21-29 parts of calcium carbonate, 1-3 parts of PE wax, 2-4 parts of stearic acid, 3-7 parts of amino-modified nano-silica, 0.5-1.5 parts of silane coupling agent KH560 and 1.5-2.5 parts of acrylate impact modifier ACR according to the mass ratio. To obtain mixture b: add 6-8 parts of nano boehmite to mixture a by atomization spraying to obtain mixture b; The mixture b is fed into a twin-screw extruder; then the twin-screw extruder is heated to melt the mixture b, which is then extruded by the twin-screw extruder and pressed, cooled and shaped to obtain the finished product.

3. The high-performance PVC composite board preparation process according to claim 2, characterized in that, Preparation of the amino-modified nano-silica The process includes the following steps: Mix 15-25 parts by weight of tetraethyl orthosilicate and 55-75 parts by weight of anhydrous ethanol, disperse the mixture by ultrasonication for 25-35 minutes, add 6-10 parts by weight of water, and hydrolyze the mixture for 1-2 hours under high-speed magnetic stirring. Then add 3-7 parts by weight of ammonia water and continue the reaction for 3-4 hours. Next, add 1-3 parts by weight of APTES, and heat and stir the mixture at 55-65°C for 3-4 hours. Dry the mixture to obtain the amino-modified nano-silica.

4. The high-performance PVC composite board preparation process according to claim 2, characterized in that, Obtaining mixture b specifically includes the following steps: transferring mixture a to a mixing tank equipped with a high-efficiency atomizing spray system, stirring mixture a at 100~300 rpm / min, loading 6~8 parts of nano-boehmite into the hopper of the spray system, starting the atomizing spray system, adjusting the nozzle pressure to 0.3~0.5 MPa, and the atomized particle size to 30~50 μm, uniformly spraying the nano-boehmite onto the agitated mixture a at a constant rate, and continuing to stir for 3~5 min after spraying to obtain mixture b.

5. The high-performance PVC composite board preparation process according to claim 2, characterized in that, The temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 110-120℃; Zone 2: 120-130℃; Zone 3: 130-140℃; Zone 4: 145-155℃; Zone 5: 155-165℃; Zone 6: 165-175℃; Zone 7: 180-190℃; and the die temperature is 205-215℃.

6. The high-performance PVC composite board preparation process according to claim 2, characterized in that, The cooling system employs a gradient cooling method, using an airflow with a wind speed of 10~15m / s and a cooling rate of 10~15℃ / min for ventilation cooling.

7. The high-performance PVC composite board preparation process according to claim 2, characterized in that, Before feeding mixture b into the twin-screw extruder, it is first subjected to vacuum degassing treatment with a vacuum degree of -0.06 to -0.08 MPa and a treatment time of 5 to 10 minutes.

8. The high-performance PVC composite board preparation process according to claim 2, characterized in that, The screw speed of the twin-screw extruder is 200~300 r / min.

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