A flame-retardant PVC wood-plastic wall panel, its preparation method and application

Abstract

This invention relates to a flame-retardant PVC wood-plastic composite wall panel, belonging to the technical field of wood-plastic composite products. The flame-retardant PVC wood-plastic composite wall panel comprises a surface layer and a core layer, with the surface layer bonded to the surface of the core layer. The surface layer is mainly prepared from polyvinyl chloride, stabilizers, chlorinated polyethylene, saline resin, phosphorus and nitrogen flame retardants, smoke suppressants, low-melting-point glass powder, kaolin, and polyethylene wax. The core layer is mainly prepared from polyvinyl chloride, wood flour, calcium carbonate, antimony white, foaming agent, foaming regulator, stabilizers, stearic acid, and polyethylene wax. This invention, through its self-developed surface and core layers, forms a flame-retardant PVC wood-plastic composite wall panel that meets the testing requirements of the Korean flame-retardant standard KS F ISO 5660-2015, ensures the mechanical properties of the flame-retardant PVC wood-plastic composite wall panel, and simultaneously reduces weight per meter, lowering the production cost of the product.

Description

Technical Field

[0001] This invention relates to the field of wood-plastic composite products technology, and in particular to a flame-retardant PVC wood-plastic wall panel, its preparation method, and its application. Background Technology

[0002] Technicians have conducted extensive research on the flame retardancy of PVC wood-plastic composite foam. However, this research has largely focused on the flame retardant effect of the product, with less attention paid to surface cracking after combustion. As PVC wood-plastic products burn, surface cracks occur, and these cracks can penetrate the entire product, making it impossible for PVC wood-plastic products to meet the testing requirements of the Korean flame retardant standard KS FISO 5660-2015.

[0003] To avoid cracking after combustion, some researchers have proposed using a ceramicization method to solve this problem. This involves adding ceramic fillers, ceramic fluxes, and flame retardants to polymer materials to create ceramic-compatible flame-retardant materials. However, this method results in PVC wood-plastic wall panels with a high content of inorganic fillers. A complete and hard surface only appears after combustion when the filler content reaches 67% or higher. Excessive fillers reduce the mechanical properties of flame-retardant PVC, increase the product's weight per meter, and consequently increase product costs. Other researchers have suggested adding low-melting-point glass powder, approximately 20-40 parts per unit area. However, this low-melting-point glass powder is expensive, and using a large amount significantly increases the overall cost of the product. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a flame-retardant PVC wood-plastic wall panel. This flame-retardant PVC wood-plastic wall panel is formed using self-developed surface and core layers. It not only meets the testing requirements of the Korean flame-retardant standard KS F ISO 5660-2015, but also ensures the mechanical properties of the flame-retardant PVC wood-plastic wall panel, while simultaneously reducing weight per meter and lowering the production cost of the product.

[0005] To achieve the above objectives, the present invention provides a flame-retardant PVC wood-plastic wall panel, comprising a surface layer and a core layer, wherein the surface layer is bonded to the surface of the core layer;

[0006] The surface layer is mainly prepared from the following raw materials in the following weight ratios:

[0007]

[0008] The core layer is mainly prepared from the following raw materials in the following weight ratios:

[0009]

[0010] During their research, the inventors discovered that conventional PVC foam flame-retardant products fail to meet the testing requirements of the Korean flame-retardant standard KS FISO 5660-2015, exhibiting cracks that penetrate the entire product after combustion. This is because, during combustion, under the influence of high heat and oxygen, the polymer molecular chains rapidly contract and break down, causing surface cracks. If ceramicization is used to address these cracks by simply introducing ceramic fillers into the system, a large proportion of ceramic fillers is required to achieve a good crack-resistant effect. However, a large proportion of ceramic fillers leads to a decrease in mechanical properties, an increase in weight per meter, and an increase in production costs. Therefore, the inventors propose preparing flame-retardant PVC wood-plastic wall panels (such as...) through a combination of a surface layer and a core layer. Figure 1 As shown, the surface layer is prepared with a formula that does not contain foaming raw materials, which has a good flame retardant effect. The core layer is prepared with a formula that contains foaming raw materials, which can reduce the overall weight per meter of the flame retardant PVC wood-plastic wall panel. Through the combination of raw materials in the surface layer and the core layer, the prepared flame retardant PVC wood-plastic wall panel can not only meet the test requirements of the Korean flame retardant standard KS F ISO 5660-2015, and will not have cracks that run through the entire product after burning, but also has good mechanical properties and reduces the weight per meter of the product.

[0011] In one embodiment, the core layer is a foamed layer, and the bonding is achieved through co-extrusion.

[0012] In one embodiment, the thickness of the surface layer is ≥2.5mm.

[0013] When the thickness of the surface layer reaches the above-mentioned level, the resulting flame-retardant PVC wood-plastic wall panel has good flame-retardant properties.

[0014] In one embodiment, the density of the core layer is 0.5 g / cm³. 3 -0.9g / cm 3 .

[0015] In one embodiment, the surface layer is a non-foamed layer.

[0016] In one embodiment, the phosphorus-nitrogen flame retardant includes an acid source and a gas source, wherein the acid source includes ammonium polyphosphate and the gas source includes melamine; the mass ratio of the acid source to the gas source is (2-4):1.

[0017] During the research process, the inventors further discovered that existing flame-retardant wall panels are typically prepared using a single formulation and lack a layered structure. Therefore, flame retardants are often directly added to the formulation to impart good flame-retardant properties to the wall panels. However, the present invention aims to prepare a flame-retardant PVC wood-plastic wall panel with a layered structure of surface and core layers. If the approach of directly adding flame retardants is still followed, the surface and core layers will delaminate when the flame-retardant PVC wood-plastic wall panel is prepared using co-extrusion technology due to the high proportion of flame retardant added. Therefore, the inventors propose introducing phosphorus-nitrogen flame retardants, low-melting-point glass powder, and kaolin into the surface layer formulation. The phosphorus-nitrogen flame retardants contain only acid and gas sources, without carbon sources. This allows the flame-retardant PVC wood-plastic wall panel to generate gas during combustion, causing the low-melting-point glass powder and other ceramic-like substances in the formulation to expand and ceramicize, forming a foamed ceramic-like substance. This results in the flame-retardant PVC wood-plastic wall panel achieving a hard, ceramic-like surface after combustion, preventing cracking, and also blocking the transmission of oxygen and heat through the foamed ceramic-like substance, thus giving the surface layer excellent flame-retardant properties. The above-mentioned surface layer formulation design requires the ceramic filler to have good sintering properties, and the low-temperature glass powder and ceramic filler to reach a certain proportion. Therefore, the inventors selected kaolin, combining it with low-temperature glass powder and phosphorus-nitrogen flame retardants, while adjusting the amounts of low-temperature glass powder and kaolin to ensure the formation of the foamed ceramic-like substance after combustion.

[0018] In one embodiment, the stabilizers in the surface layer and core layer include at least one of lead salt stabilizers, calcium-zinc stabilizers, rare earth stabilizers, and organotin stabilizers;

[0019] The foaming agent includes at least one of azodicarbonamide, sodium bicarbonate, and zinc oxide.

[0020] The smoke suppressant includes at least one of ammonium octanoate and molybdenum trioxide;

[0021] The foaming regulator includes acrylate copolymers.

[0022] In one embodiment, the foaming agent comprises azodicarbonamide, sodium bicarbonate, and zinc oxide, wherein the mass ratio of azodicarbonamide, sodium bicarbonate, and zinc oxide is 1:(2-4):(0.05-0.15).

[0023] In one embodiment, the polyvinyl chloride in the surface layer and the core layer includes at least one of SG-7 type polyvinyl chloride resin and SG-8 type polyvinyl chloride resin;

[0024] The sarin resin is an ionic polymer of ethylene-(meth)acrylate zinc salt with a melt flow index of 2-4 g / 10 min;

[0025] The melting point of the low-melting-point glass powder is 300–500°C;

[0026] The intrinsic viscosity (25°C) of the acrylate copolymer is 8.0-9.0 dL·g. -1 .

[0027] In one embodiment, the intrinsic viscosity (25°C) of the acrylate copolymer is 8.3 dL·g. -1 .

[0028] In one embodiment, the low-melting-point glass powder has a melting point of 350°C.

[0029] The present invention also provides a method for preparing the flame-retardant PVC wood-plastic wall panel, comprising the following steps:

[0030] Preparation of surface layer mixture: Weigh the raw materials for the surface layer, mix them, and mix them under cooling conditions to obtain the surface layer mixture;

[0031] Preparation of core layer mixture: Weigh the raw materials for the core layer, mix wood flour and calcium carbonate, add polyvinyl chloride, antimony white, stabilizer and foaming regulator, mix, add foaming agent, polyethylene wax and stearic acid, mix, mix under cooling conditions to obtain core layer mixture;

[0032] Preparation of flame-retardant PVC wood-plastic wall panels: The surface layer mixture and the core layer mixture are co-extruded and cooled to obtain flame-retardant PVC wood-plastic wall panels.

[0033] In one embodiment, in the step of preparing the surface layer mixture, the raw materials for the surface layer are weighed, mixed to a temperature of 120-130°C, and then mixed to a temperature of 35-45°C under cooling conditions;

[0034] In the step of preparing the core layer mixture, the raw materials for the core layer are weighed, wood flour and calcium carbonate are mixed to a temperature of 85-95℃, polyvinyl chloride, antimony white, stabilizer and foaming regulator are added, and the mixture is mixed to a temperature of 100-105℃, foaming agent, polyethylene wax and stearic acid are added, and the mixture is mixed to a temperature of 120-130℃, and then mixed to a temperature of 35-45℃ under cooling conditions.

[0035] In one embodiment, in the step of preparing flame-retardant PVC wood-plastic wall panels, the co-extrusion is achieved by a co-extruder, and the temperatures of each section from the hopper to the confluence core are: 120-140℃, 130-155℃, 150-165℃, 160-180℃, and 170-185℃; the temperatures of each section from the hopper to the die are: 120-140℃, 130-155℃, 150-165℃, 155-170℃, 160-180℃, and 185-195℃.

[0036] The operating conditions of the main unit include: the screw speed is 9-13 r / min, and the speed of the main feed hopper screw is 15-30 r / min;

[0037] The co-extruder operating conditions include: screw speed of 6-9 r / min and main feed hopper feed screw speed of 13-20 r / min.

[0038] The present invention also provides the application of the flame-retardant PVC wood-plastic wall panel in building materials.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] This invention discloses a flame-retardant PVC wood-plastic wall panel, its preparation method, and its application. The flame-retardant PVC wood-plastic wall panel is formed using a self-developed surface layer and core layer. The core layer is prepared using PVC wood-plastic foaming technology, which reduces the density and weight per meter of the product, thereby lowering production costs while providing thermal insulation. The surface layer uses a flame-retardant PVC material formula, ensuring that the wall panel meets the required mechanical and flame-retardant properties. The resulting flame-retardant PVC wood-plastic wall panel has a density of 0.5 g / cm³. 3 -0.9g / cm 3 With a density close to that of solid wood, it has good heat insulation properties; at the same time, the product meets the testing requirements of the Korean flame retardant standard KS F ISO 5660-2015; after the flame retardant test, no cracks appeared on the product surface. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of the flame-retardant PVC wood-plastic composite board of the present invention, wherein 1 is the surface layer and 2 is the core layer;

[0042] Figure 2 This is a schematic diagram of surface cracking after combustion in Comparative Example 2;

[0043] Figure 3 This is a schematic diagram of the surface condition after combustion in Example 2. Detailed Implementation

[0044] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0046] source:

[0047] Unless otherwise specified, all reagents, materials, and equipment used in this embodiment are commercially available; unless otherwise specified, all test methods are conventional test methods in this field.

[0048] Example 1

[0049] A flame-retardant PVC wood-plastic wall panel and its preparation method.

[0050] The specific preparation method is as follows:

[0051] I. Weigh the materials according to the following formula:

[0052] 1. Surface material:

[0053]

[0054]

[0055] 2. Core material:

[0056]

[0057] In this embodiment, the foaming agent is a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator is an acrylate copolymer with an intrinsic viscosity (25°C) of 8.3 dL·g. -1 .

[0058] II. Preparation of flame-retardant PVC wood-plastic wall panels.

[0059] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0060] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0061] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0062] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 2.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 2.5mm.

[0063] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0064] Example 2

[0065] A flame-retardant PVC wood-plastic wall panel and its preparation method.

[0066] The specific preparation method is as follows:

[0067] I. Weigh the materials according to the following formula:

[0068] 1. Surface material:

[0069]

[0070] 2. Core material:

[0071]

[0072] In this embodiment, the foaming agent is a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator is an acrylate copolymer with an intrinsic viscosity (25°C) of 8.3 dL·g. -1 .

[0073] II. Preparation of flame-retardant PVC wood-plastic wall panels.

[0074] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0075] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0076] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0077] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 2.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 2.5mm.

[0078] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0079] Example 3

[0080] A flame-retardant PVC wood-plastic wall panel and its preparation method.

[0081] The specific preparation method is as follows:

[0082] I. Weigh the materials according to the following formula:

[0083] 1. Surface material:

[0084]

[0085] 2. Core material:

[0086]

[0087] In this embodiment, the foaming agent is a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator is an acrylate copolymer with an intrinsic viscosity (25°C) of 8.3 dL·g. -1 .

[0088] II. Preparation of flame-retardant PVC wood-plastic wall panels.

[0089] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0090] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0091] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0092] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 2.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 2.5mm.

[0093] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0094] Example 4

[0095] A flame-retardant PVC wood-plastic wall panel and its preparation method.

[0096] The specific preparation method is as follows:

[0097] I. Weigh the materials according to the following formula.

[0098] 1. Surface material:

[0099]

[0100] 2. Core material:

[0101]

[0102]

[0103] In this embodiment, the foaming agent is a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator is an acrylate copolymer with an intrinsic viscosity (25°C) of 8.3 dL·g. -1 .

[0104] II. Preparation of flame-retardant PVC wood-plastic wall panels.

[0105] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0106] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0107] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0108] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 2.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 2.5mm.

[0109] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0110] Example 5

[0111] A flame-retardant PVC wood-plastic wall panel and its preparation method.

[0112] The specific preparation method is as follows:

[0113] I. Weigh the materials according to the following formula:

[0114] 1. Surface material:

[0115]

[0116]

[0117] 2. Core material:

[0118]

[0119] In this embodiment, the foaming agent is a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator is an acrylate copolymer with an intrinsic viscosity (25°C) of 8.3 dL·g. -1 .

[0120] II. Preparation of flame-retardant PVC wood-plastic wall panels.

[0121] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0122] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0123] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0124] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 2.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 2.5mm.

[0125] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0126] Example 6

[0127] A flame-retardant PVC wood-plastic wall panel and its preparation method.

[0128] The specific preparation method is as follows:

[0129] I. Weigh the materials according to the following formula:

[0130] 1. Surface material:

[0131]

[0132] 2. Core material:

[0133]

[0134] In this embodiment, the foaming agent is a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator is an acrylate copolymer with an intrinsic viscosity (25°C) of 8.3 dL·g. -1 .

[0135] II. Preparation of flame-retardant PVC wood-plastic wall panels.

[0136] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0137] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0138] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0139] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 1.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 1.5mm.

[0140] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0141] Example 7

[0142] A flame-retardant PVC wood-plastic wall panel and its preparation method.

[0143] The specific preparation method is as follows:

[0144] I. Weigh the materials according to the following formula:

[0145] 1. Surface material:

[0146]

[0147] 2. Core material:

[0148]

[0149] In this embodiment, the foaming agent is a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator is an acrylate copolymer with an intrinsic viscosity (25°C) of 8.3 dL·g. -1 .

[0150] II. Preparation of flame-retardant PVC wood-plastic wall panels.

[0151] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0152] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0153] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0154] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 1.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 1.5mm.

[0155] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0156] Example 8

[0157] 1. Weigh the materials according to the following formula.

[0158] Surface material:

[0159]

[0160] 2. Core material:

[0161]

[0162]

[0163] In this embodiment, the foaming agent is a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator is an acrylate copolymer with an intrinsic viscosity (25°C) of 8.3 dL·g. -1 .

[0164] II. Preparation of flame-retardant PVC wood-plastic wall panels.

[0165] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0166] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0167] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0168] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 1.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 1.5mm.

[0169] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0170] Comparative Example 1

[0171] A PVC wood-plastic wall panel and its preparation method.

[0172] The specific preparation method is as follows:

[0173] I. Weigh the materials according to the following formula:

[0174]

[0175] II. Preparation of PVC wood-plastic wall panels.

[0176] 1. Put the above materials into a high-speed mixer and mix until the material temperature reaches 120°C; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40°C to obtain the flame-retardant wall panel mixture.

[0177] 2. Add the mixed material to the hopper of the conical twin extruder. Set the temperatures of each section of the main extruder from the hopper to the die as follows: Zone 1 130℃, Zone 2 140℃, Zone 3 165℃, Zone 4 170℃, confluence core 170℃, and die 185℃. The screw speed of the main extruder is 11 r / min, and the speed of the feed screw of the main feed hopper is 30 r / min.

[0178] 3. The material is extruded through a twin-screw extruder and flows through a die (without a co-extrusion layer, the overall wall thickness of the product is 7mm) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain flame-retardant PVC wall panels.

[0179] 4. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0180] Comparative Example 2

[0181] A PVC wood-plastic wall panel and its preparation method.

[0182] The specific preparation method is as follows:

[0183] I. Weigh the materials according to the following formula.

[0184]

[0185] In this comparative example, the foaming agent was a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator was an acrylate copolymer with an intrinsic viscosity (25℃) of 8.3 dL·g. -1 .

[0186] II. Preparation of PVC wood-plastic wall panels.

[0187] 1. Place the oak powder, low melting point glass powder, and kaolin from the formula into a high-speed mixing pot and mix until the temperature reaches 90°C; add polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator, and mix at high speed until the material temperature reaches 105°C; add foaming agent, polyethylene wax, and stearic acid, and continue stirring until the temperature reaches 120°C; transfer the material to a cold mixing pot and continue mixing until the material temperature drops to 40°C to obtain the PVC wood-plastic wall panel mixture.

[0188] 2. Add the mixed material to the hopper of the conical twin extruder. Set the temperatures of each section of the main extruder from the hopper to the die as follows: Zone 1 130℃, Zone 2 140℃, Zone 3 165℃, Zone 4 170℃, confluence core 170℃, and die 185℃. The screw speed of the main extruder is 9 r / min, and the speed of the feed screw of the main feed hopper is 20 r / min.

[0189] 3. The material is extruded through a twin-screw extruder and flows through a die (without a co-extrusion layer, the overall wall thickness of the product is 7mm) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain flame-retardant PVC wall panels.

[0190] 4. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0191] Comparative Example 3

[0192] A PVC wood-plastic wall panel and its preparation method.

[0193] The specific preparation method is as follows:

[0194] I. Weigh the materials according to the following formula.

[0195] 1. Surface material:

[0196]

[0197] 2. Core material:

[0198]

[0199] In this comparative example, the foaming agent was a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator was an acrylate copolymer with an intrinsic viscosity (25℃) of 8.3 dL·g. -1 .

[0200] II. Preparation of PVC wood-plastic wall panels.

[0201] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0202] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0203] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0204] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 2.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 2.5mm.

[0205] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0206] Comparative Example 4

[0207] A PVC wood-plastic wall panel and its preparation method.

[0208] The specific preparation method is as follows:

[0209] I. Weigh the materials according to the following formula.

[0210] 1. Surface material:

[0211]

[0212] 2. Core material:

[0213]

[0214]

[0215] In this comparative example, the foaming agent was a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator was an acrylate copolymer with an intrinsic viscosity (25℃) of 8.3 dL·g. -1 .

[0216] II. Preparation of PVC wood-plastic wall panels.

[0217] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0218] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are placed in a high-speed mixing pot and mixed to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the core layer mixture.

[0219] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0220] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 2.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 2.5mm.

[0221] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0222] Comparative Example 5

[0223] A PVC wood-plastic wall panel and its preparation method.

[0224] The specific preparation method is as follows:

[0225] I. Weigh the materials according to the following formula.

[0226] 1. Surface material:

[0227]

[0228]

[0229] 2. Core material:

[0230]

[0231] In this comparative example, the foaming agent was a composite foaming agent composed of azodicarbonamide, sodium bicarbonate, and zinc oxide in a mass ratio of 1:3:0.1; the foaming regulator was an acrylate copolymer with an intrinsic viscosity (25℃) of 8.3 dL·g. -1 .

[0232] II. Preparation of PVC wood-plastic wall panels.

[0233] 1. Preparation of surface layer mixture: Put the surface layer material into a high-speed mixer and mix until the material temperature reaches 120℃; put the high-temperature material into a cold mixing pot and continue mixing until the material temperature drops to 40℃ to obtain the surface layer mixture;

[0234] 2. Preparation of core layer mixture: Oak powder and light calcium carbonate in the core layer material are mixed in a high-speed mixing pot to a temperature of 90°C; polyvinyl chloride, antimony white, calcium zinc stabilizer, and foaming regulator are added, and the mixture is mixed at high speed until the material temperature reaches 105°C; foaming agent, polyethylene wax, and stearic acid are added, and the mixture is stirred continuously until the temperature reaches 120°C; the mixture is then transferred to a cold mixing pot and mixed until the material temperature drops to 40°C to obtain the flame-retardant wall panel core layer mixture.

[0235] 3. Preparation of Flame-Retardant PVC Wood-Plastic Wall Panels: The mixed surface layer material is added to the hopper of the conical twin extruder, and the core layer material is added to the hopper of the conical twin extruder main unit. The temperatures of each section of the co-extruder from the hopper to the confluence core are set as follows: Zone 1 130℃, Main Unit Zone 2 150℃, Main Unit Zone 3 165℃, Main Unit Zone 4 180℃, Confluence Core 185℃; the temperatures of each section of the main extruder from the hopper to the die are set as follows: Zone 1 130℃, Main Unit Zone 2 140℃, Main Unit Zone 3 165℃, Main Unit Zone 4 170℃, Confluence Core 170℃, Die 185℃. The screw speed of the main unit is 9 r / min, the screw speed of the main feed hopper is 20 r / min, the screw speed of the co-extruder is 6 r / min, and the screw speed of the main feed hopper is 13 r / min.

[0236] 4. The material is extruded through a twin-screw extruder and flows through a die (the overall wall thickness of the product is 7mm, of which the co-extruded layer is 1.5mm thick) to form a blank. After exiting the die, the blank enters the sizing table for cooling to obtain a flame-retardant PVC foam wall panel with a surface layer thickness of 1.5mm.

[0237] 5. The formed flame-retardant PVC foam wall panels are continuously conveyed forward by the traction unit and cut into standard sizes at the cutting table.

[0238] Experimental Example

[0239] The performance of the PVC wood-plastic wall panels prepared in the above embodiments and comparative examples was tested, and the results are shown in the table below.

[0240] Table 1. Performance test results of PVC wood-plastic wall panels prepared in each embodiment and comparative example.

[0241]

[0242]

[0243] Comparative Example 2 showed surface cracking after combustion, such as Figure 2 As shown, the surface condition after combustion in Example 2 is as follows. Figure 3 As shown.

[0244] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0245] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A flame-retardant PVC wood-plastic wall panel, characterized in that, It includes a surface layer and a core layer, wherein the surface layer is bonded to the surface of the core layer; The surface layer is mainly prepared from the following raw materials in the following weight ratios: The core layer is mainly prepared from the following raw materials in the following weight ratios:

2. The flame-retardant PVC wood-plastic wall panel according to claim 1, characterized in that, The core layer is a foamed layer, and the bonding is achieved through co-extrusion.

3. The flame-retardant PVC wood-plastic wall panel according to claim 1, characterized in that, The thickness of the surface layer is ≥2.5mm.

4. The flame-retardant PVC wood-plastic wall panel according to claim 1, characterized in that, The phosphorus-nitrogen flame retardant comprises an acid source and a gas source, wherein the acid source includes ammonium polyphosphate and the gas source includes melamine; the mass ratio of the acid source to the gas source is (2-4):

1.

5. The flame-retardant PVC wood-plastic wall panel according to claim 1, characterized in that, The stabilizers in the surface layer and core layer include at least one of lead salt stabilizers, calcium-zinc stabilizers, rare earth stabilizers, and organotin stabilizers. The foaming agent includes at least one of azodicarbonamide, sodium bicarbonate, and zinc oxide. The smoke suppressant includes at least one of ammonium octamolybdate and molybdenum trioxide; The foaming regulator includes acrylate copolymers.

6. The flame-retardant PVC wood-plastic wall panel according to claim 5, characterized in that, The foaming agent includes azodicarbonamide, sodium bicarbonate, and zinc oxide, with a mass ratio of azodicarbonamide, sodium bicarbonate, and zinc oxide of 1:(2-4):(0.05-0.15).

7. The method for preparing the flame-retardant PVC wood-plastic wall panel according to any one of claims 1-6, characterized in that, Includes the following steps: Preparation of surface layer mixture: Weigh the raw materials for the surface layer, mix them, and mix them under cooling conditions to obtain the surface layer mixture; Preparation of core layer mixture: Weigh the raw materials for the core layer, mix wood flour and calcium carbonate, add polyvinyl chloride, antimony white, stabilizer and foaming regulator, mix, add foaming agent, polyethylene wax and stearic acid, mix, mix under cooling conditions to obtain core layer mixture; Preparation of flame-retardant PVC wood-plastic wall panels: The surface layer mixture and the core layer mixture are co-extruded and cooled to obtain flame-retardant PVC wood-plastic wall panels.

8. The preparation method according to claim 7, characterized in that, In the step of preparing the surface layer mixture, the raw materials for the surface layer are weighed, mixed to a temperature of 120-130℃, and then mixed to a temperature of 35-45℃ under cooling conditions; In the step of preparing the core layer mixture, the raw materials for the core layer are weighed, wood flour and calcium carbonate are mixed to a temperature of 85-95℃, polyvinyl chloride, antimony white, stabilizer and foaming regulator are added, and the mixture is mixed to a temperature of 100-105℃, foaming agent, polyethylene wax and stearic acid are added, and the mixture is mixed to a temperature of 120-130℃, and then mixed to a temperature of 35-45℃ under cooling conditions.

9. The preparation method according to claim 7, characterized in that, In the step of preparing flame-retardant PVC wood-plastic wall panels, the co-extrusion is achieved through a co-extruder. The temperatures of each section from the hopper to the confluence core are: 120-140℃, 130-155℃, 150-165℃, 160-180℃, and 170-185℃, respectively; the temperatures of each section from the hopper to the die are: 120-140℃, 130-155℃, 150-165℃, 155-170℃, 160-180℃, and 185-195℃, respectively. The operating conditions of the main unit include: the screw speed is 9-13 r / min, and the speed of the main feed hopper screw is 15-30 r / min; The co-extruder operating conditions include: screw speed of 6-9 r / min and main feed hopper feed screw speed of 13-20 r / min.

10. The application of the flame-retardant PVC wood-plastic wall panel according to any one of claims 1-6 in building materials.

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