High-flame-retardant low-smoke environment-friendly PVC foamed wallboard and preparation method thereof

Abstract

The application relates to a high-flame-retardant low-smoke environment-friendly PVC foamed wallboard and a preparation method thereof, and belongs to the technical field of PVC foamed wallboards. The high-flame-retardant low-smoke environment-friendly PVC foamed wallboard is mainly prepared from the following components: 100 parts of PVC resin, 5-8 parts of calcium-zinc composite heat stabilizer, 2-5 parts of epoxy soybean oil, 8-15 parts of modified magnesium-aluminum hydrotalcite-based synergistic flame retardant, 5-12 parts of zinc stannate, 10-20 parts of aluminum hydroxide, 3-8 parts of zinc borate, 10-20 parts of nano calcium carbonate, 3-6 parts of acrylate impact modifier, 4-6 parts of PVC foaming regulator, 0.8-1.2 parts of polyethylene wax and 0.8-1.5 parts of PVC foaming agent. The PVC wallboard prepared by the application has the advantages of high flame retardancy, low smoke and the like, reaches the standard of difficult-to-burn materials, and has high impact strength and bending strength.

Description

Technical Field

[0001] This invention belongs to the technical field of PVC foamed wall panels, and relates to a high flame retardant, low smoke, and environmentally friendly PVC foamed wall panel and its preparation method. Background Technology

[0002] PVC foam board, also known as Chevron board or Andy board, is chemically composed of polyvinyl chloride, hence it is also called foamed PVC board. PVC foam board possesses properties such as corrosion resistance, moisture resistance, mildew resistance, non-absorbency, drillability, sawability, planability, ease of thermoforming, and hot bending. Based on its hardness, it can be divided into soft PVC and rigid PVC; based on its manufacturing process, it can be divided into PVC skinned foam board and PVC free-foam board. PVC foam board is widely used in passenger car and train carriage roofs, core layers of boxes, interior decoration panels, building exterior wall panels, interior decoration panels, office, residential, and public building partitions, commercial decorative racks, cleanroom panels, ceiling panels, screen printing, computer lettering, advertising signs, exhibition boards, signage, photo album boards, and other industries. It is also used in chemical anti-corrosion projects, thermoformed parts, cold storage panels, special cold insulation projects, environmental protection panels, sports equipment, aquaculture materials, coastal moisture-proof facilities, water-resistant materials, art materials, and various lightweight partitions to replace glass ceilings.

[0003] PVC foam board is a new type of green and environmentally friendly material with properties such as light weight, acid and alkali resistance, moisture resistance, water resistance, heat insulation, and sound insulation, making it an ideal alternative to wood, aluminum, and composite boards. Although rigid PVC itself has certain flame-retardant properties, the foaming process significantly reduces the flame-retardant performance of PVC materials—it rapidly pulverizes after burning in an open flame at high temperatures, making it difficult to extinguish the flame and producing large amounts of dense smoke, causing serious loss of life and property. While adding flame retardants significantly improves the material's flame retardancy, it also affects the foaming process and cell structure, reducing the foaming ratio and disrupting the uniformity of the cells. Traditional PVC foam boards typically use halogenated flame retardants such as antimony trioxide and decabromodiphenyl ether, which produce large amounts of toxic fumes and corrosive gases during combustion, leading to environmental problems. Furthermore, the synergistic effect of a single flame retardant is insufficient, and there are blind spots in the combustion temperature control range.

[0004] Therefore, developing a PVC foamed wall panel formulation and preparation method that combines high flame retardancy, low smoke emission, and environmental friendliness is of significant practical importance and market value. Summary of the Invention

[0005] The main objective of this invention is to provide a PVC foamed wall panel and its preparation method, which has advantages such as high flame retardancy, low smoke, and environmental friendliness.

[0006] The present invention employs the following technical solutions to achieve the above objectives: A high flame-retardant, low-smoke, environmentally friendly PVC foam wall panel is mainly made from the following components: 100 parts PVC resin, 5-8 parts calcium-zinc composite heat stabilizer, 2-5 parts epoxidized soybean oil, 8-15 parts modified magnesium-aluminum hydrotalcite-based synergistic flame retardant, 5-12 parts zinc stannate, 10-20 parts aluminum hydroxide, 3-8 parts zinc borate, 10-20 parts nano calcium carbonate, 3-6 parts acrylate impact modifier, 4-6 parts PVC foaming regulator, 0.8-1.2 parts polyethylene wax, and 0.8-1.5 parts PVC foaming agent.

[0007] Specifically, The preparation method of the modified magnesium-aluminum hydrotalcite-based synergistic flame retardant is as follows: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter referred to as DOPO) was added to ethanol, heated to 80-100℃, and stirred at 200 rpm until DOPO was completely dissolved. Then, ethanol-diluted silane coupling agent was added, the temperature was raised to 120-150℃, and the reaction was carried out at a constant temperature for 2-3 hours. Then, the temperature was lowered to 80℃ and stirred for 20-30 minutes to obtain the reactant. Magnesium aluminum hydrotalcite and ammonium polyphosphate were added to the reactant, the temperature was raised to 120-140℃, and the reaction was carried out at a constant temperature for 2-3 hours with stirring at 200-250 rpm. Then, the mixture was cooled to room temperature, centrifuged, and the precipitate was collected, washed with ethanol-water solution, dried, and ball-milled to a particle size of 100-150 mesh to obtain the modified magnesium aluminum hydrotalcite-based synergistic flame retardant.

[0008] In a further preferred embodiment, the amounts of each raw material used in the preparation method of the modified magnesium-aluminum hydrotalcite-based synergistic flame retardant are as follows: DOPO 8-10 parts by weight, silane coupling agent KH570 2-3 parts by weight, magnesium-aluminum hydrotalcite 75-80 parts by weight, and ammonium polyphosphate 2-5 parts by weight.

[0009] The preparation method of the PVC foaming agent is as follows: Stearic acid and titanate coupling agent are mixed and sprayed onto the surface of sodium bicarbonate. The mixture is then mixed at 90-100℃ and 1200-1500r / min for 20-30min to obtain coated sodium bicarbonate. Azodicarbonamide and coated sodium hydroxide were stirred and mixed at 150-200 r / min for 10-15 min. Zinc oxide, sodium acryloyl dimethyl taurate copolymer and calcium stearate were added. The mixture was heated to 80-90℃ and stirred at 200-220 r / min for 20-30 min to obtain the mixture. The mixture is fed into a granulator, extruded and granulated, dried, and ball-milled to obtain PVC foaming agent; More preferably, the amounts of each raw material used in the PVC foaming agent preparation method are as follows: 70-85 parts by weight of azodicarbonamide, 10-20 parts by weight of coated sodium hydroxide, 1.5-3.5 parts by weight of zinc oxide, 1.5-2 parts by weight of sodium acryloyldimethyl taurate copolymer, and 1-2.5 parts by weight of calcium stearate.

[0010] More preferably, the amounts of each raw material used in the preparation of the coated sodium bicarbonate are as follows: Stearic acid 1.5~2.5 parts by weight, titanate coupling agent 0.5~1 parts by weight, sodium bicarbonate 100 parts by weight.

[0011] The preparation method of the PVC foaming regulator is as follows: Pentaerythritol stearate was heated to 80-90℃ and stirred at a constant temperature of 120-150 rpm until completely melted. Oleic diethanolamide was added and stirred at a constant temperature of 150-180 rpm for 40-60 min to obtain a mixture. Talc and polyethylene glycol were added to the mixture and stirred at a constant temperature of 200-220 rpm for 10-15 min. Then, butylated hydroxytoluene, calcium carbonate, and stearic acid were added. The mixture was heated to 90-100℃ and stirred at a constant temperature of 250-300 rpm for 30-40 min. Epoxidized soybean oil was then added and stirred for another 20-30 min to obtain a molten material. The molten material was fed into a granulator, extruded and granulated, dried, and ball-milled to obtain a PVC foaming stabilizer.

[0012] More preferably, the amounts of each raw material used in the PVC foaming regulator preparation method are as follows: Pentaerythritol stearate 45-50 parts by weight, oleic acid diethanolamide 25-30 parts by weight, talc 2-4 parts by weight, polyethylene glycol 1-2 parts by weight, butylated hydroxytoluene 1-3 parts by weight, calcium carbonate 5-8 parts by weight, stearic acid 2-4 parts by weight, and epoxidized soybean oil 3-8 parts by weight.

[0013] This invention provides a method for preparing the high flame-retardant, low-smoke, environmentally friendly PVC foamed wall panel, comprising the following steps: First, the raw materials are mixed. Add calcium-zinc composite heat stabilizer and epoxidized soybean oil to PVC resin while stirring, mix well and then heat up. When the temperature rises to 80~90℃, add modified magnesium aluminum hydrotalcite-based synergistic flame retardant, zinc stannate, aluminum hydroxide, and zinc borate, mix well, and then raise the temperature. When the material temperature reaches 100~110℃, add nano calcium carbonate, acrylate impact modifier, PVC foaming regulator, and polyethylene wax, mix well, and then raise the temperature. When the material temperature reaches 115~120℃, add PVC foaming agent, continue mixing for 30~60s, cool, and obtain the mixture. Secondly, plasticize and extrude. The mixture is fed into an extruder, where it is plasticized and melted to form a uniform melt, which is then extruded. Finally, molding and cooling. The extruded melt enters the shaping and cooling device, where the shape and size are fixed by the shaping mold, and cold water is circulated for cooling to shape the wall panel. During the cooling process, the wall panel is pulled by a traction machine, and the traction speed is consistent with the extrusion speed. After shaping and cooling, the wall panel is cut into the preset size to obtain the finished PVC foam wall panel.

[0014] More preferably, the total mixing time in the raw material mixing step is controlled at 8 to 12 minutes, and the temperature of the mixed materials is controlled at 115 to 125°C.

[0015] In a further preferred embodiment, during the plasticizing and extrusion step, the temperatures of each section of the extruder are set as follows: feeding section 150~160℃, compression section 165~175℃, metering section 170~180℃, and die head temperature 165~170℃; the screw speed is controlled at 180~220 r / min.

[0016] Compared with the prior art, the present invention has the following beneficial effects: High flame retardant performance: By constructing a multi-component synergistic halogen-free flame retardant system with DOPO modified magnesium aluminum hydrotalcite, zinc stannate, aluminum hydroxide and zinc borate as the core, the product oxygen index can reach more than 50%, which meets the standard of flame-retardant materials. Moreover, the flame retardant does not contain halogens and does not produce corrosive gases when burning.

[0017] Low smoke and environmentally friendly: The smoke-suppressing effect of the constructed multi-component synergistic halogen-free flame retardant system can significantly reduce the smoke density when PVC is burning. The product as a whole meets environmental protection requirements, with no formaldehyde release and heavy metal content that meets RoHS standards.

[0018] Excellent mechanical properties: By optimizing the composition of foaming agent and foaming regulator, the board has sufficient bending strength and impact resistance while maintaining low density.

[0019] Good processing stability: The synergistic stabilization system of calcium-zinc composite heat stabilizer and epoxidized soybean oil provides a stable thermal environment for the foaming process, resulting in uniform and fine cells and excellent product surface quality. Attached Figure Description

[0020] Figure 1 The wall panel appearance is as follows: A is the wall panel of Example 1, B is the wall panel of Example 2, C is the wall panel of Example 3, D is the wall panel of Comparative Example 1, E is the wall panel of Comparative Example 2, and F is the wall panel of Comparative Example 3. Detailed Implementation

[0021] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope of protection of the claims of this application.

[0022] Example 1: A high flame-retardant, low-smoke, environmentally friendly PVC foamed wall panel and its preparation method, comprising the following steps: Step 1: Raw material preparation and pretreatment 1. Preparation of modified magnesium aluminum hydrotalcite-based synergistic flame retardant: First, commercially available magnesium aluminum hydrotalcite (Mg4Al2(OH)·12H2O) was dried in an oven at 110℃ for 5 hours, cooled to room temperature, pulverized, and passed through a 200-mesh sieve to obtain pretreated magnesium aluminum hydrotalcite for later use; 3 parts by weight of commercially available silane coupling agent KH570 were mixed with ethanol at a volume ratio of 1:1 to obtain the diluted coupling agent. Next, add 10 parts by weight of DOPO to an appropriate amount of ethanol, heat to 100℃, and stir at 200 rpm until the DOPO is completely dissolved to form a homogeneous solution; then slowly add the diluted coupling agent (1~2 drops / s). After the addition is complete, heat to 150℃ and react at a constant temperature for 3 hours; keep the reaction under reflux to prevent solvent evaporation and raw material loss; after the reaction is complete, cool to 80℃ and stir for 30 minutes to ensure uniform dispersion of the reactants; Finally, 80 parts by weight of pretreated magnesium aluminum hydrotalcite and 5 parts by weight of ammonium polyphosphate were slowly added to the above reactants. The mixture was heated to 140°C and stirred at a constant temperature of 200 r / min for 3 h (the stirring speed was adjusted to 250 r / min as needed during the reaction). After stirring, the mixture was stopped and cooled to room temperature. The precipitate was centrifuged, washed repeatedly with an ethanol-water solution with a volume ratio of 1:1, dried, and ball-milled to a particle size of 100-150 mesh to obtain the modified magnesium aluminum hydrotalcite-based synergistic flame retardant. 2. Preparation of PVC foaming agent First, mix 2.5 parts by weight of stearic acid and 1 part by weight of titanate coupling agent TC-201 evenly, then spray it onto the surface of 100 parts by weight of sodium bicarbonate under stirring. Mix at 100°C and 1200 r / min for 30 min to obtain coated sodium bicarbonate for later use. Then, 70 parts by weight of azodicarbonamide and 10 parts by weight of coated sodium hydroxide were stirred and mixed at 150 r / min for 15 min. 1.5 parts by weight of zinc oxide, 1.5 parts by weight of sodium acryloyl dimethyl taurate copolymer, and 1 part by weight of calcium stearate were added. The mixture was heated to 80℃ and stirred at a constant temperature of 200 r / min for 30 min to obtain a mixture. The mixture was fed into a granulator, and the granulation temperature was controlled at 110℃ and the screw speed at 200 r / min. The mixture was extruded, dried, and ball-milled to a particle size of 100~150 mesh to obtain a PVC foaming agent. 3. Preparation of PVC foaming regulator First, heat 50 parts by weight of pentaerythritol stearate to 80°C and stir at 150 r / min until completely melted; then slowly add 30 parts by weight of oleic acid diethanolamide and stir at 180 r / min for 40 min to obtain a mixture. Next, add 4 parts by weight of talc powder and 2 parts by weight of polyethylene glycol to the mixture, stir at 220 r / min for 10 min, then add 3 parts by weight of dibutylhydroxytoluene, 8 parts by weight of calcium carbonate and 4 parts by weight of stearic acid, heat to 100℃, stir at 300 r / min for 30 min, then add 8 parts by weight of epoxidized soybean oil, and continue stirring for 20 min to obtain the molten material. Finally, the molten material is fed into a granulator, extruded and granulated, dried, and ball-milled to a particle size of 100-150 mesh to obtain a PVC foaming stabilizer. Step 2: High-speed mixing 100 parts by weight of PVC resin were put into a high-speed mixer. 5 parts by weight of calcium-zinc composite heat stabilizer and 2 parts by weight of epoxidized soybean oil were added in sequence under low-speed stirring. After mixing evenly, the mixture was heated. After the temperature rises to 90℃, add 8 parts by weight of modified magnesium aluminum hydrotalcite-based synergistic flame retardant, 12 parts by weight of zinc stannate, 10 parts by weight of aluminum hydroxide, and 8 parts by weight of zinc borate, mix at high speed and heat up. When the material temperature reaches 110℃, add 20 parts by weight of nano calcium carbonate, 3 parts by weight of acrylic ester impact modifier, 6 parts by weight of PVC foaming regulator, and 0.8 parts by weight of polyethylene wax, mix at high speed and heat up. When the material temperature reaches 120℃, add 1.5 parts by weight of PVC foaming agent and continue mixing for 30 seconds; The total high-speed mixing time is controlled within 8-12 minutes, and the final mixture temperature is controlled between 115-125℃. Once the material reaches the preset temperature, it is discharged into a cold mixer to cool to below 40℃ for later use. Step 3: Plasticize and extrude The cooled mixture is fed into a parallel twin-screw extruder. The temperatures of each section of the extruder are set as follows: feeding section 160℃, compression section 175℃, metering section 180℃, and die head temperature 170℃. The screw speed is controlled at 220 r / min. The material is fully plasticized and melted to form a uniform melt and then extruded. Step 4: Molding and Cooling The extruded melt enters the shaping and cooling device, where the shape and size are fixed by the shaping mold. At the same time, cold water (30℃) is circulated for cooling to shape the wall panel. During the cooling process, the wall panel is pulled by a traction machine, and the traction speed is consistent with the extrusion speed (3m / min). After shaping and cooling, the wall panel is cut into the preset size to obtain the finished PVC foam wall panel.

[0023] Example 2: A high flame-retardant, low-smoke, environmentally friendly PVC foamed wall panel and its preparation method, comprising the following steps: Step 1: Raw material preparation and pretreatment 1. Preparation of modified magnesium aluminum hydrotalcite-based synergistic flame retardant: First, commercially available magnesium aluminum hydrotalcite (Mg4Al2(OH)·12H2O) was dried in an oven at 110℃ for 5 hours, cooled to room temperature, pulverized, and passed through a 200-mesh sieve to obtain pretreated magnesium aluminum hydrotalcite for later use; 3 parts by weight of commercially available silane coupling agent KH570 were mixed with ethanol at a volume ratio of 1:1 to obtain the diluted coupling agent. Next, add 8 parts by weight of DOPO to an appropriate amount of ethanol, heat to 80°C, and stir at 200 rpm until the DOPO is completely dissolved to form a homogeneous solution; then slowly add the diluted coupling agent (1~2 drops / s). After the addition is complete, heat to 120°C and react at a constant temperature for 2 hours; keep the reaction under reflux to prevent solvent evaporation and raw material loss; after the reaction is complete, cool to 80°C and stir for 20 minutes to ensure uniform dispersion of the reactants. Finally, 75 parts by weight of pretreated magnesium aluminum hydrotalcite and 2 parts by weight of ammonium polyphosphate were slowly added to the above reactants. The mixture was heated to 120°C and stirred at a constant temperature of 200 r / min for 2-3 hours (the stirring speed was adjusted to 250 r / min as needed during the reaction). After stirring, the mixture was stopped and cooled to room temperature. The precipitate was centrifuged, washed repeatedly with an ethanol-water solution with a volume ratio of 1:1, dried, and ball-milled to a particle size of 100-150 mesh to obtain the modified magnesium aluminum hydrotalcite-based synergistic flame retardant. 2. Preparation of PVC foaming agent First, mix 1.5 parts by weight of stearic acid and 0.5 parts by weight of titanate coupling agent TC-201 evenly, then spray the mixture onto the surface of 100 parts by weight of sodium bicarbonate under stirring. Mix at 90°C and 1500 r / min for 20 min to obtain coated sodium bicarbonate for later use. Then, 85 parts by weight of azodicarbonamide and 20 parts by weight of coated sodium hydroxide were stirred and mixed at 200 r / min for 10 min. Then, 3.5 parts by weight of zinc oxide, 2 parts by weight of sodium acryloyl dimethyl taurate copolymer and 2.5 parts by weight of calcium stearate were added. The mixture was heated to 90℃ and stirred at 220 r / min for 20 min to obtain a mixture. The mixture was fed into a granulator, and the granulation temperature was controlled at 130℃ and the screw speed was 150 r / min. The mixture was extruded and granulated, dried, and ball-milled to a particle size of 100~150 mesh to obtain PVC foaming agent. 3. Preparation of PVC foaming regulator First, heat 45 parts by weight of pentaerythritol stearate to 90°C and stir at 120 r / min until completely melted; then slowly add 25 parts by weight of oleic acid diethanolamide and stir at 150 r / min for 60 min to obtain a mixture. Next, add 2 parts by weight of talc powder and 1 part by weight of polyethylene glycol to the mixture, stir at 200 r / min for 15 min, then add 1 part by weight of dibutylhydroxytoluene, 5 parts by weight of calcium carbonate and 2 parts by weight of stearic acid, heat to 90℃, stir at 250 r / min for 40 min, then add 3 parts by weight of epoxidized soybean oil, and continue stirring for 30 min to obtain the molten material. Finally, the molten material is fed into a granulator, extruded and granulated, dried, and ball-milled to a particle size of 100-150 mesh to obtain a PVC foaming stabilizer. Step 2: High-speed mixing 100 parts by weight of PVC resin were put into a high-speed mixer. 8 parts by weight of calcium-zinc composite heat stabilizer and 5 parts by weight of epoxidized soybean oil were added sequentially under low-speed stirring. After mixing evenly, the mixture was heated. After the temperature rises to 80℃, add 15 parts by weight of modified magnesium aluminum hydrotalcite-based synergistic flame retardant, 5 parts by weight of zinc stannate, 20 parts by weight of aluminum hydroxide, and 3 parts by weight of zinc borate, mix at high speed and heat up. When the material temperature reaches 100℃, add 10 parts by weight of nano calcium carbonate, 6 parts by weight of acrylic ester impact modifier, 4 parts by weight of PVC foaming regulator, and 1.2 parts by weight of polyethylene wax, mix at high speed and heat up. When the material temperature reaches 115℃, add 0.8 parts by weight of PVC foaming agent and continue mixing for 60 seconds; The total high-speed mixing time is controlled within 8-12 minutes, and the final mixture temperature is controlled between 115-125℃. Once the material reaches the preset temperature, it is discharged into a cold mixer to cool to below 40℃ for later use. Step 3: Plasticize and extrude The cooled mixture is fed into a parallel twin-screw extruder. The temperatures of each section of the extruder are set as follows: feeding section 150℃, compression section 165℃, metering section 170℃, and die head temperature 165℃. The screw speed is controlled at 180 r / min. The material is fully plasticized and melted to form a uniform melt and then extruded. Step 4: Molding and Cooling The extruded melt enters the shaping and cooling device, where the shape and size are fixed by the shaping mold. At the same time, cold water (20℃) is circulated for cooling to shape the wall panel. During the cooling process, the wall panel is pulled by a traction machine, and the traction speed is kept consistent with the extrusion speed (2m / min). After shaping and cooling, the wall panel is cut into the preset size to obtain the finished PVC foam wall panel.

[0024] Example 3: A high flame-retardant, low-smoke, environmentally friendly PVC foamed wall panel and its preparation method, comprising the following steps: Step 1: Raw material preparation and pretreatment 1. Preparation of modified magnesium aluminum hydrotalcite-based synergistic flame retardant: First, commercially available magnesium aluminum hydrotalcite (Mg4Al2(OH)·12H2O) was dried in an oven at 110℃ for 4 hours, cooled to room temperature, pulverized, and passed through a 200-mesh sieve to obtain pretreated magnesium aluminum hydrotalcite for later use; 2 parts by weight of commercially available silane coupling agent KH570 were mixed with ethanol at a volume ratio of 1:1 to obtain the diluted coupling agent. Next, add 9 parts by weight of DOPO to an appropriate amount of ethanol, heat to 90°C, and stir at 200 rpm until the DOPO is completely dissolved to form a homogeneous solution; then slowly add the diluted coupling agent (1~2 drops / s). After the addition is complete, heat to 130°C and react at a constant temperature for 3 hours; keep the reaction under reflux to prevent solvent evaporation and raw material loss; after the reaction is complete, cool to 80°C and stir for 20 minutes to ensure uniform dispersion of the reactants. Finally, 80 parts by weight of pretreated magnesium aluminum hydrotalcite and 3 parts by weight of ammonium polyphosphate were slowly added to the above reactants. The mixture was heated to 140°C and stirred at a constant temperature of 200 r / min for 2-3 hours (the stirring speed was adjusted to 250 r / min as needed during the reaction). After stirring, the mixture was stopped and cooled to room temperature. The precipitate was centrifuged, washed repeatedly with an ethanol-water solution with a volume ratio of 1:1, dried, and ball-milled to a particle size of 100-150 mesh to obtain the modified magnesium aluminum hydrotalcite-based synergistic flame retardant. 2. Preparation of PVC foaming agent First, mix 2.0 parts by weight of stearic acid and 0.8 parts by weight of titanate coupling agent TC-201 evenly, then spray the mixture onto the surface of 100 parts by weight of sodium bicarbonate under stirring. Mix at 100°C and 1500 r / min for 20 min to obtain coated sodium bicarbonate for later use. Then, 80 parts by weight of azodicarbonamide and 15 parts by weight of coated sodium hydroxide were stirred and mixed at 200 r / min for 10 min. 2.5 parts by weight of zinc oxide, 2 parts by weight of sodium acryloyl dimethyl taurate copolymer, and 2.0 parts by weight of calcium stearate were added. The mixture was heated to 90℃ and stirred at 200 r / min for 30 min to obtain a mixture. The mixture was fed into a granulator, and the granulation temperature was controlled at 130℃ and the screw speed at 150 r / min. The mixture was extruded, dried, and ball-milled to a particle size of 100~150 mesh to obtain a PVC foaming agent. 3. Preparation of PVC foaming regulator First, heat 50 parts by weight of pentaerythritol stearate to 90°C and stir at 150 r / min until completely melted; then slowly add 25 parts by weight of oleic acid diethanolamide and stir at 180 r / min for 40 min to obtain a mixture. Next, add 3 parts by weight of talc powder and 2 parts by weight of polyethylene glycol to the mixture, stir at 220 r / min for 10 min, then add 2 parts by weight of dibutylhydroxytoluene, 6 parts by weight of calcium carbonate and 3 parts by weight of stearic acid, heat to 100℃, stir at 300 r / min for 30 min, then add 5 parts by weight of epoxidized soybean oil, and continue stirring for 30 min to obtain the molten material; Finally, the molten material is fed into a granulator, extruded and granulated, dried, and ball-milled to a particle size of 100-150 mesh to obtain a PVC foaming stabilizer.

[0025] Step 2: High-speed mixing 100 parts by weight of PVC resin were put into a high-speed mixer. 6 parts by weight of calcium-zinc composite heat stabilizer and 3 parts by weight of epoxidized soybean oil were added in sequence under low-speed stirring. After mixing evenly, the mixture was heated. After the temperature rises to 90℃, add 12 parts by weight of modified magnesium aluminum hydrotalcite-based synergistic flame retardant, 10 parts by weight of zinc stannate, 15 parts by weight of aluminum hydroxide, and 5 parts by weight of zinc borate, mix at high speed and heat up. When the material temperature reaches 110℃, add 15 parts by weight of nano calcium carbonate, 5 parts by weight of acrylic ester impact modifier, 5 parts by weight of PVC foaming regulator, and 1.0 part by weight of polyethylene wax, stir at high speed and heat up. When the material temperature reaches 120℃, add 1.2 parts by weight of PVC foaming agent and continue mixing for 40 seconds; The total high-speed mixing time is controlled within 8-12 minutes, and the final mixture temperature is controlled between 115-125℃. Once the material reaches the preset temperature, it is discharged into a cold mixer to cool to below 40℃ for later use. Step 3: Plasticize and extrude The cooled mixture is fed into a parallel twin-screw extruder. The temperatures of each section of the extruder are set as follows: feeding section 160℃, compression section 175℃, metering section 180℃, and die head temperature 170℃. The screw speed is controlled at 220 r / min. The material is fully plasticized and melted to form a uniform melt and then extruded. Step 4: Molding and Cooling The extruded melt enters the shaping and cooling device, where the shape and size are fixed by the shaping mold. At the same time, cold water (20℃) is circulated for cooling to shape the wall panel. During the cooling process, the wall panel is pulled by a traction machine, and the traction speed is kept consistent with the extrusion speed (2m / min). After shaping and cooling, the wall panel is cut into the preset size to obtain the finished PVC foam wall panel.

[0026] Comparative Example 1: A high flame-retardant, low-smoke, environmentally friendly PVC foamed wall panel and its preparation method, comprising the following steps: Step 1: Raw material preparation and pretreatment 1. Preparation of modified magnesium aluminum hydrotalcite-based synergistic flame retardant: First, commercially available magnesium aluminum hydrotalcite (Mg4Al2(OH)·12H2O) was dried in an oven at 110℃ for 4 hours, cooled to room temperature, pulverized, and passed through a 200-mesh sieve to obtain pretreated magnesium aluminum hydrotalcite for later use; 2 parts by weight of commercially available silane coupling agent KH570 were mixed with ethanol at a volume ratio of 1:1 to obtain the diluted coupling agent. Next, add 9 parts by weight of DOPO to an appropriate amount of ethanol, heat to 90°C, and stir at 200 rpm until the DOPO is completely dissolved to form a homogeneous solution; then slowly add the diluted coupling agent (1~2 drops / s). After the addition is complete, heat to 130°C and react at a constant temperature for 3 hours; keep the reaction under reflux to prevent solvent evaporation and raw material loss; after the reaction is complete, cool to 80°C and stir for 20 minutes to ensure uniform dispersion of the reactants. Finally, 80 parts by weight of pretreated magnesium aluminum hydrotalcite and 3 parts by weight of ammonium polyphosphate were slowly added to the above reactants. The mixture was heated to 140°C and stirred at a constant temperature of 200 r / min for 2-3 hours (the stirring speed was adjusted to 250 r / min as needed during the reaction). After stirring, the mixture was stopped and cooled to room temperature. The precipitate was centrifuged, washed repeatedly with an ethanol-water solution with a volume ratio of 1:1, dried, and ball-milled to a particle size of 100-150 mesh to obtain the modified magnesium aluminum hydrotalcite-based synergistic flame retardant. 2. Preparation of PVC foaming agent First, mix 2.0 parts by weight of stearic acid and 0.8 parts by weight of titanate coupling agent TC-201 evenly, then spray the mixture onto the surface of 100 parts by weight of sodium bicarbonate under stirring. Mix at 100°C and 1500 r / min for 20 min to obtain coated sodium bicarbonate for later use. Then, 80 parts by weight of azodicarbonamide and 15 parts by weight of coated sodium hydroxide were stirred and mixed at 200 r / min for 10 min. 2.5 parts by weight of zinc oxide, 2 parts by weight of sodium acryloyl dimethyl taurate copolymer, and 2.0 parts by weight of calcium stearate were added. The mixture was heated to 90℃ and stirred at 200 r / min for 30 min to obtain a mixture. The mixture was fed into a granulator, and the granulation temperature was controlled at 130℃ and the screw speed at 150 r / min. The mixture was extruded, dried, and ball-milled to a particle size of 100~150 mesh to obtain a PVC foaming agent. Step 2: High-speed mixing 100 parts by weight of PVC resin were put into a high-speed mixer. 6 parts by weight of calcium-zinc composite heat stabilizer and 3 parts by weight of epoxidized soybean oil were added in sequence under low-speed stirring. After mixing evenly, the mixture was heated. After the temperature rises to 90℃, add 12 parts by weight of modified magnesium aluminum hydrotalcite-based synergistic flame retardant, 10 parts by weight of zinc stannate, 15 parts by weight of aluminum hydroxide, and 5 parts by weight of zinc borate, mix at high speed and heat up. When the material temperature reaches 110℃, add 15 parts by weight of nano calcium carbonate, 5 parts by weight of acrylic ester impact modifier, and 1.0 part by weight of polyethylene wax, stir at high speed and heat up. When the material temperature reaches 120℃, add 1.2 parts by weight of PVC foaming agent and continue mixing for 40 seconds; The total high-speed mixing time is controlled within 8-12 minutes, and the final mixture temperature is controlled between 115-125℃. Once the material reaches the preset temperature, it is discharged into a cold mixer to cool to below 40℃ for later use. Step 3: Plasticize and extrude The cooled mixture is fed into a parallel twin-screw extruder. The temperatures of each section of the extruder are set as follows: feeding section 160℃, compression section 175℃, metering section 180℃, and die head temperature 170℃. The screw speed is controlled at 220 r / min. The material is fully plasticized and melted to form a uniform melt and then extruded. Step 4: Molding and Cooling The extruded melt enters the shaping and cooling device, where the shape and size are fixed by the shaping mold. At the same time, cold water (20℃) is circulated for cooling to shape the wall panel. During the cooling process, the wall panel is pulled by a traction machine, and the traction speed is kept consistent with the extrusion speed (2m / min). After shaping and cooling, the wall panel is cut into the preset size to obtain the finished PVC foam wall panel.

[0027] Comparative Example 2: A high flame-retardant, low-smoke, environmentally friendly PVC foamed wall panel and its preparation method, comprising the following steps: Step 1: Raw material preparation and pretreatment 1. Preparation of modified magnesium aluminum hydrotalcite-based synergistic flame retardant: First, commercially available magnesium aluminum hydrotalcite (Mg4Al2(OH)·12H2O) was dried in an oven at 110℃ for 4 hours, cooled to room temperature, pulverized, and passed through a 200-mesh sieve to obtain pretreated magnesium aluminum hydrotalcite for later use; 2 parts by weight of commercially available silane coupling agent KH570 were mixed with ethanol at a volume ratio of 1:1 to obtain the diluted coupling agent. Next, add 9 parts by weight of DOPO to an appropriate amount of ethanol, heat to 90°C, and stir at 200 rpm until the DOPO is completely dissolved to form a homogeneous solution; then slowly add the diluted coupling agent (1~2 drops / s). After the addition is complete, heat to 130°C and react at a constant temperature for 3 hours; keep the reaction under reflux to prevent solvent evaporation and raw material loss; after the reaction is complete, cool to 80°C and stir for 20 minutes to ensure uniform dispersion of the reactants. Finally, 80 parts by weight of pretreated magnesium aluminum hydrotalcite and 3 parts by weight of ammonium polyphosphate were slowly added to the above reactants. The mixture was heated to 140°C and stirred at a constant temperature of 200 r / min for 2-3 hours (the stirring speed was adjusted to 250 r / min as needed during the reaction). After stirring, the mixture was stopped and cooled to room temperature. The precipitate was centrifuged, washed repeatedly with an ethanol-water solution with a volume ratio of 1:1, dried, and ball-milled to a particle size of 100-150 mesh to obtain the modified magnesium aluminum hydrotalcite-based synergistic flame retardant. 2. Preparation of PVC foaming regulator First, heat 50 parts by weight of pentaerythritol stearate to 90°C and stir at 150 r / min until completely melted; then slowly add 25 parts by weight of oleic acid diethanolamide and stir at 180 r / min for 40 min to obtain a mixture. Next, add 3 parts by weight of talc powder and 2 parts by weight of polyethylene glycol to the mixture, stir at 220 r / min for 10 min, then add 2 parts by weight of dibutylhydroxytoluene, 6 parts by weight of calcium carbonate and 3 parts by weight of stearic acid, heat to 100℃, stir at 300 r / min for 30 min, then add 5 parts by weight of epoxidized soybean oil, and continue stirring for 30 min to obtain the molten material; Finally, the molten material is fed into a granulator, extruded and granulated, dried, and ball-milled to a particle size of 100-150 mesh to obtain a PVC foaming stabilizer.

[0028] Step 2: High-speed mixing 100 parts by weight of PVC resin were put into a high-speed mixer. 6 parts by weight of calcium-zinc composite heat stabilizer and 3 parts by weight of epoxidized soybean oil were added in sequence under low-speed stirring. After mixing evenly, the mixture was heated. After the temperature rises to 90℃, add 12 parts by weight of modified magnesium aluminum hydrotalcite-based synergistic flame retardant, 10 parts by weight of zinc stannate, 15 parts by weight of aluminum hydroxide, and 5 parts by weight of zinc borate, mix at high speed and heat up. When the material temperature reaches 110℃, add 15 parts by weight of nano calcium carbonate, 5 parts by weight of acrylic ester impact modifier, 5 parts by weight of PVC foaming regulator, and 1.0 part by weight of polyethylene wax, stir at high speed and heat up. When the material temperature reaches 120℃, add 1.2 parts by weight of commercially available AC foaming agent and continue mixing for 40 seconds; The total high-speed mixing time is controlled within 8-12 minutes, and the final mixture temperature is controlled between 115-125℃. Once the material reaches the preset temperature, it is discharged into a cold mixer to cool to below 40℃ for later use. Step 3: Plasticize and extrude The cooled mixture is fed into a parallel twin-screw extruder. The temperatures of each section of the extruder are set as follows: feeding section 160℃, compression section 175℃, metering section 180℃, and die head temperature 170℃. The screw speed is controlled at 220 r / min. The material is fully plasticized and melted to form a uniform melt and then extruded. Step 4: Molding and Cooling The extruded melt enters the shaping and cooling device, where the shape and size are fixed by the shaping mold. At the same time, cold water (20℃) is circulated for cooling to shape the wall panel. During the cooling process, the wall panel is pulled by a traction machine, and the traction speed is kept consistent with the extrusion speed (2m / min). After shaping and cooling, the wall panel is cut into the preset size to obtain the finished PVC foam wall panel.

[0029] Comparative Example 3: A high flame-retardant, low-smoke, environmentally friendly PVC foamed wall panel and its preparation method, comprising the following steps: Step 1: High-speed mixing 100 parts by weight of PVC resin were put into a high-speed mixer. 6 parts by weight of calcium-zinc composite heat stabilizer and 3 parts by weight of epoxidized soybean oil were added in sequence under low-speed stirring. After mixing evenly, the mixture was heated. After the temperature rises to 90°C, add 10 parts by weight of zinc stannate, 15 parts by weight of aluminum hydroxide, and 5 parts by weight of zinc borate, mix at high speed and heat up. When the material temperature reaches 110℃, add 15 parts by weight of nano calcium carbonate, 5 parts by weight of acrylate impact modifier, 0.2 parts by weight of zinc oxide, and 1.0 part by weight of polyethylene wax, stir at high speed and heat up; When the material temperature reaches 120℃, add 1.2 parts by weight of commercially available AC foaming agent and continue mixing for 40 seconds; The total high-speed mixing time is controlled within 8-12 minutes, and the final mixture temperature is controlled between 115-125℃. Once the material reaches the preset temperature, it is discharged into a cold mixer to cool to below 40℃ for later use. Step 2: Plasticizing and extruding The cooled mixture is fed into a parallel twin-screw extruder. The temperatures of each section of the extruder are set as follows: feeding section 160℃, compression section 175℃, metering section 180℃, and die head temperature 170℃. The screw speed is controlled at 220 r / min. The material is fully plasticized and melted to form a uniform melt and then extruded. Step 3: Molding and Cooling The extruded melt enters the shaping and cooling device, where the shape and size are fixed by the shaping mold. At the same time, cold water (20℃) is circulated for cooling to shape the wall panel. During the cooling process, the wall panel is pulled by a traction machine, and the traction speed is kept consistent with the extrusion speed (2m / min). After shaping and cooling, the wall panel is cut into the preset size to obtain the finished PVC foam wall panel.

[0030] Performance testing I. Appearance Morphology of PVC Foamed Wall Panels Obtained by Different Preparation Methods PVC foamed wall panel samples were prepared according to the methods described in Examples 1-3 and Comparative Examples 1-3. After liquid nitrogen treatment, the samples were brittle and fractured. The surfaces were then sprayed with gold, and the morphology of the foam cells in the cross-section was observed using a scanning electron microscope. At the same time, the mechanical properties of the wall panels were measured.

[0031] since Figure 1 The results show that the PVC foamed wall panels prepared in Examples 1-3 have dense, moderately sized, and uniformly distributed cells; the PVC wall panels prepared in Comparative Example 1 have larger, fewer, and unevenly distributed cells. Comparative Example 1 lacks a PVC foaming regulator, which cannot effectively regulate the foaming efficiency. The presence of the flame retardant affects the foaming process, resulting in uneven foaming; the PVC wall panels prepared in Comparative Example 2 have dense cells with smaller pore sizes. Comparative Example 2 uses a foaming agent, resulting in poor foaming effect, with excessively dense cells and small pore sizes; the PVC wall panels prepared in Comparative Example 3 have uneven cell morphology, with some cells having thick walls and some areas without cells. Comparative Example 3 uses a traditional wall panel preparation method, resulting in poor foaming effect.

[0032] As can be seen from the results in Table 1, the impact strength and flexural strength of Examples 1-3 in Comparative Example 1 are significantly better than those of Comparative Example 2 and Comparative Example 3. The PVC foamed wall panels prepared in Comparative Examples 2 and 3 have poor impact strength and flexural strength due to different cell sizes and uneven cell distribution. The PVC wall panels prepared in Comparative Example 1 have small and dense cells, resulting in excessively high density. Although the impact strength and flexural strength are enhanced, they are not suitable for lightweight decoration.

[0033] Table 1 Comparison of the performance of PVC foamed wall panels II. Flame retardant properties of PVC foamed wall panels prepared by different methods PVC foamed wall panel samples were prepared according to the methods described in Examples 1-3 and Comparative Examples 1-3, and their flame retardant and combustion performance was determined.

[0034] The PVC foamed wall panels prepared in Examples 1-3 and Comparative Examples 1-2 can self-extinguish in a short time without dripping. However, overall, the foamed wall panels prepared in Examples 1-3 have the shortest self-extinguishing time, while the PVC foamed wall panels prepared in Comparative Example 3 have the longest self-extinguishing time and dripping occurs.

[0035] Table 2 Comparison of the combustion performance of PVC foam wall panels

Claims

1. A high flame-retardant, low-smoke, environmentally friendly PVC foam wall panel, characterized in that, It is mainly prepared from the following components: 100 parts PVC resin, 5-8 parts calcium-zinc composite heat stabilizer, 2-5 parts epoxidized soybean oil, 8-15 parts modified magnesium-aluminum hydrotalcite-based synergistic flame retardant, 5-12 parts zinc stannate, 10-20 parts aluminum hydroxide, 3-8 parts zinc borate, 10-20 parts nano calcium carbonate, 3-6 parts acrylate impact modifier, 4-6 parts PVC foaming regulator, 0.8-1.2 parts polyethylene wax, and 0.8-1.5 parts PVC foaming agent.

2. The PVC foamed wall panel as described in claim 1, characterized in that, The preparation method of the modified magnesium-aluminum hydrotalcite-based synergistic flame retardant is as follows: DOPO was added to ethanol, heated to 80-100℃, and stirred at 200 rpm until the DOPO was completely dissolved. Then, ethanol-diluted silane coupling agent was added, the temperature was raised to 120-150℃, and the reaction was carried out at a constant temperature for 2-3 hours. The temperature was then lowered to 80℃, and the mixture was stirred for 20-30 minutes to obtain the reactant. Magnesium aluminum hydrotalcite and ammonium polyphosphate were added to the reactant, the temperature was raised to 120-140℃, and the mixture was stirred at 200-250 rpm for 2-3 hours. The mixture was then cooled to room temperature, centrifuged, and the precipitate was collected. The precipitate was washed with an ethanol-water solution, dried, and ball-milled to a particle size of 100-150 mesh to obtain the modified magnesium aluminum hydrotalcite-based synergistic flame retardant.

3. The PVC foamed wall panel as described in claim 2, characterized in that, The amounts of each raw material used in the preparation method of the modified magnesium aluminum hydrotalcite-based synergistic flame retardant are as follows: DOPO 8~10 parts by weight, silane coupling agent KH570 2~3 parts by weight, magnesium aluminum hydrotalcite 75~80 parts by weight, and ammonium polyphosphate 2~5 parts by weight.

4. The PVC foamed wall panel as described in claim 1, characterized in that, The preparation method of the PVC foaming agent is as follows: Stearic acid and titanate coupling agent are mixed and sprayed onto the surface of sodium bicarbonate. The mixture is then stirred at 90-100℃ and 1200-1500 rpm for 20-30 minutes to obtain coated sodium bicarbonate. Azodicarbonamide and coated sodium hydroxide are stirred and mixed at 150-200 rpm for 10-15 minutes. Zinc oxide, sodium acryloyl dimethyl taurate copolymer, and calcium stearate are added. The mixture is heated to 80-90℃ and stirred at 200-220 rpm for 20-30 minutes to obtain a mixture. The mixture is fed into a granulator, extruded and granulated, dried, and ball-milled to obtain a PVC foaming agent.

5. The PVC foamed wall panel as described in claim 4, characterized in that, The amounts of each raw material used in the PVC foaming agent preparation method are as follows: 70-85 parts by weight of azodicarbonamide, 10-20 parts by weight of coated sodium hydroxide, 1.5-3.5 parts by weight of zinc oxide, 1.5-2 parts by weight of sodium acryloyldimethyl taurate copolymer, and 1-2.5 parts by weight of calcium stearate.

6. The PVC foamed wall panel as described in claim 5, characterized in that, The amounts of each raw material used in the preparation of the coated sodium bicarbonate are as follows: Stearic acid 1.5~2.5 parts by weight, titanate coupling agent 0.5~1 parts by weight, sodium bicarbonate 100 parts by weight.

7. The PVC foamed wall panel as described in claim 1, characterized in that, The preparation method of the PVC foaming regulator is as follows: Pentaerythritol stearate was heated to 80-90℃ and stirred at a constant temperature of 120-150 rpm until completely melted. Oleic diethanolamide was added and stirred at a constant temperature of 150-180 rpm for 40-60 min to obtain a mixture. Talc and polyethylene glycol were added to the mixture and stirred at a constant temperature of 200-220 rpm for 10-15 min. Then, butylated hydroxytoluene, calcium carbonate, and stearic acid were added. The mixture was heated to 90-100℃ and stirred at a constant temperature of 250-300 rpm for 30-40 min. Epoxidized soybean oil was then added and stirred for another 20-30 min to obtain a molten material. The molten material was fed into a granulator, extruded and granulated, dried, and ball-milled to obtain a PVC foaming stabilizer.

8. The PVC foamed wall panel as described in claim 7, characterized in that, The amounts of each raw material used in the PVC foaming regulator preparation method are as follows: Pentaerythritol stearate 45-50 parts by weight, oleic acid diethanolamide 25-30 parts by weight, talc 2-4 parts by weight, polyethylene glycol 1-2 parts by weight, butylated hydroxytoluene 1-3 parts by weight, calcium carbonate 5-8 parts by weight, stearic acid 2-4 parts by weight, and epoxidized soybean oil 3-8 parts by weight.

9. The PVC foamed wall panel according to any one of claims 1 to 8, characterized in that, The method for preparing the PVC foamed wall panel includes the following steps: First, mix the ingredients: Add calcium-zinc composite heat stabilizer and epoxidized soybean oil to PVC resin while stirring, mix well and then heat up. When the temperature rises to 80~90℃, add modified magnesium aluminum hydrotalcite-based synergistic flame retardant, zinc stannate, aluminum hydroxide, and zinc borate, mix well, and then raise the temperature. When the material temperature reaches 100~110℃, add nano calcium carbonate, acrylate impact modifier, PVC foaming regulator, and polyethylene wax, mix well, and then raise the temperature. When the material temperature reaches 115~120℃, add PVC foaming agent, continue mixing for 30~60s, cool, and obtain the mixture. Secondly, plasticize and extrude: The mixture is fed into an extruder, where it is plasticized and melted to form a uniform melt, which is then extruded. Finally, molding and cooling: The extruded melt enters the shaping and cooling device, where the shape and size are fixed by the shaping mold, and cold water is circulated for cooling to shape the wall panel. During the cooling process, the wall panel is pulled by a traction machine, and the traction speed is consistent with the extrusion speed. After shaping and cooling, the wall panel is cut into the preset size to obtain the finished PVC foam wall panel.

10. The PVC foamed wall panel as described in claim 9, characterized in that, In the raw material mixing step, the total mixing time is controlled at 8-12 minutes, and the temperature of the mixed material is controlled at 115-125℃. In the plasticizing and extrusion step, the temperatures of each section of the extruder are set as follows: feeding section 150-160℃, compression section 165-175℃, metering section 170-180℃, and die head temperature 165-170℃. The screw speed is controlled at 180-220 r / min.

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