Multi-layer composite extruded sheet and preparation method thereof

Abstract

The invention relates to the field of extruded sheets, and provides a multi-layer composite extruded sheet and a preparation method thereof. The multi-layer composite extruded sheet comprises a functional surface layer, a middle layer and an inner layer, the functional surface layer is prepared from the following raw materials in parts by weight: 45-55 parts of polystyrene, 25-35 parts of graphite modified polystyrene, 4-6 parts of nano silicon dioxide, 8-12 parts of a flame retardant, 1-2 parts of an antioxidant and 2-4 parts of a lubricant; the middle layer is prepared from the following raw materials in parts by weight: 60-70 parts of polystyrene, 14-16 parts of glass fiber chopped strands, 5-7 parts of graft modified glass fibers, 8-12 parts of a flame retardant, 2-4 parts of a coupling agent and 1.5-2.5 parts of a foaming nucleating agent. According to the multi-layer composite extruded sheet provided by the invention, by designing a reasonable hierarchical structure, the balance between heat preservation and structural strength is realized, and the requirement of multiple functions is met.

Description

Technical Field

[0001] The present invention relates to the technical field of extruded boards, and specifically, to a multi-layer composite extruded board and a preparation method thereof. Background Art

[0002] As a high-performance building insulation material, the extruded board has been widely used in the construction field due to its characteristics such as light weight, high compressive strength, water non-absorbency, air non-permeability, wear resistance, and heat insulation. Especially in wall insulation and low-temperature storage floors, the extruded board has become one of the preferred construction materials due to its advantages of good quality and low price. However, with the continuous development of the construction industry, the performance requirements for the extruded board are also constantly increasing, and traditional extruded boards are difficult to meet the market demand in some aspects.

[0003] The extruded board is a material formed by continuous extrusion and foaming. The hard film formed on its surface is uniform and flat, and the internal fully closed-cell foaming is continuous and uniform, showing a honeycomb structure. This structure endows the extruded board with excellent physical and chemical properties. For example, its high compressive strength enables it to bear large loads without deformation; the light weight characteristic facilitates transportation and construction; the water non-absorbency and air non-permeability characteristics effectively prevent the penetration of moisture and air, thereby improving the insulation and moisture-proof performance of buildings.

[0004] At present, the production technology of the extruded board has been relatively mature, but there are still some problems in actual applications. For example, there is still room for improvement in the insulation performance, structural strength, and multifunctionality of traditional extruded boards. In addition, with the rise of prefabricated buildings and modular buildings, new requirements have also been put forward for the dimensional accuracy, installation convenience, and environmental protection performance of the extruded board.

[0005] Although traditional extruded boards have excellent insulation performance, they still have deficiencies in structural strength. Especially in some buildings that need to bear large loads or are in special environments, a single-layer extruded board is difficult to meet the requirements. And with the development of the construction industry, the functional requirements for the extruded board are getting higher and higher. For example, it is required that the extruded board simultaneously has multiple functions such as heat insulation, sound insulation, and fire prevention. However, traditional extruded boards have obvious deficiencies in multifunctionality. Based on this, the present invention proposes a multi-layer composite extruded board and a preparation method thereof. Summary of the Invention

[0006] The present invention proposes a multi-layer composite extruded board and a preparation method thereof. By designing a reasonable hierarchical structure, the balance between heat insulation and structural strength is achieved, meeting the requirements of multiple functions such as heat insulation, sound insulation, and fire prevention.

[0007] The technical solution of the present invention is as follows: In the first aspect, the present invention proposes a multi-layer composite extruded board, including a functional surface layer, an intermediate layer, and an inner layer; The functional surface layer is composed of the following raw materials in parts by weight: 45-55 parts of polystyrene, 25-35 parts of graphite-modified polystyrene, 4-6 parts of nano-silica, 8-12 parts of flame retardant, 1-2 parts of antioxidant, and 2-4 parts of lubricant; The intermediate layer is composed of the following raw materials in parts by weight: 60-70 parts of polystyrene, 14-16 parts of short glass fiber filaments, 5-7 parts of graft-modified glass fiber, 8-12 parts of flame retardant, 2-4 parts of coupling agent, and 1.5-2.5 parts of foaming nucleating agent; The inner layer is composed of the following raw materials in parts by weight: 50-60 parts of polystyrene, 25-35 parts of CO2 supercritical foaming agent, 4-6 parts of zinc oxide-coated montmorillonite, 0.4-0.6 parts of carbon nanotubes, and 2-3 parts of quaternary ammonium salt antistatic agent.

[0008] As a further technical solution, the thickness ratio of the functional surface layer, intermediate layer, and inner layer is 14-16:35-45:42-48.

[0009] As a further technical solution, the preparation method of the graft-modified glass fiber includes: ultrasonically dispersing 2-3 g of octavinylsilsesquioxane in 200-220 mL of ethanol, adding 0.1-0.2 g of benzoyl peroxide initiator, and magnetically stirring to dissolve to obtain a grafting solution; immersing the silylated glass fiber therein, heating to 60-70 °C under nitrogen protection, stirring and reacting at 700-900 rpm for 5-7 h, controlling the dosage ratio of silylated glass fiber to grafting solution to be 1:20-24 g / mL. After the reaction, ultrasonically clean with ethanol and deionized water 3-5 times in sequence, and vacuum dry at 60-80 °C for 12-14 h to obtain the graft-modified glass fiber.

[0010] As a further technical solution, the preparation method of the silylated glass fiber includes: heating the glass fiber to 550-600 °C at a rate of 3-4 °C / min and holding for 2-3 h to obtain pretreated glass fiber; mixing a silane coupling agent, ethanol, and water with a volume ratio of 1:18-20:2, adjusting the pH to 4-5 with acetic acid; then immersing the pretreated fiber therein, ultrasonically oscillating at 60-70 °C and 40-50 kHz for 30-40 min, standing for 22-24 h, and vacuum drying at 60-80 °C for 6-10 h to obtain the silylated glass fiber.

[0011] As a further technical solution, the preparation method of the zinc oxide-coated montmorillonite includes: dissolving zinc acetate dihydrate in ethanol, adding sodium hydroxide to adjust the pH to 9-11, ultrasonically dispersing at 50-60 °C for 5-7 hours to obtain zinc oxide sol, mixing montmorillonite with zinc oxide sol, adding a hydrazine hydrate solution, ultrasonically stirring at 70-80 °C for 6-7 hours, and then reacting at 165-175 °C for 22-24 hours, followed by suction filtration, washing, and drying to obtain it.

[0012] As a further technical solution, the weight ratio of zinc acetate dihydrate: ethanol: montmorillonite and hydrazine hydrate solution is 10-20: 30-50: 1-3: 1.5-3.5.

[0013] As a further technical solution, the flame retardants in the functional surface layer include ammonium polyphosphate and pentaerythritol with a weight ratio of 2-3: 4-6, the antioxidant is antioxidant 1010, and the lubricant is calcium stearate.

[0014] As a further technical solution, the average length of the short cut glass fiber filaments in the intermediate layer is 3-5 mm, the flame retardants include magnesium hydroxide and aluminum hydroxide with a weight ratio of 1: 3-4, the silane coupling agent is silane coupling agent KH550, and the foaming nucleating agent is talcum powder; the quaternary ammonium salt antistatic agent in the inner layer is octadecyl trimethyl ammonium chloride.

[0015] In the second aspect, the present invention provides a method for preparing a multi-layer composite extruded board, and the steps include: mixing the raw materials of the functional surface layer, the intermediate layer and the inner layer respectively, controlling the die head temperature to be 105-110 °C, using three-layer co-extrusion foaming to extrude a prefabricated board, controlling the roller temperature to be 80-90 °C, pressing the board through a three-roll calender to make the board thickness 20-100 mm, and the ratio of the calendering speed to the extrusion speed is 1: 1.2; performing plasma treatment at a power of 4-6 kW and a speed of 2.5-3.5 m / min, and after slitting, curing at a constant temperature of 55-65 °C for 23-25 h to obtain the multi-layer composite extruded board.

[0016] As a further technical solution, the temperature of the functional surface layer extruder: zone 1 is 185-195 °C, zone 2 is 195-205 °C, zone 3 is 205-215 °C; the temperature of the intermediate layer extruder: zone 1 is 175-185 °C, zone 2 is 190-200 °C, zone 3 is 200-210 °C; the temperature of the inner layer extruder: zone 1 is 170-180 °C, zone 2 is 180-190 °C, zone 3 is 190-200 °C; and the injection pressure of the inner layer foaming agent is 12-15 MPa.

[0017] The working principle and beneficial effects of the present invention are as follows: In the present invention, the multi-layer composite extruded board adopts a three-layer structure design. Among them, the functional surface layer is mainly responsible for fire prevention, weather resistance and anti-aging; the intermediate layer mainly provides mechanical support and heat preservation performance; the inner layer forms a uniform cell structure through supercritical foaming technology to further improve the heat preservation performance. And this structure design makes the material have more balanced and excellent performance as a whole; the functional surface layer (high density), the intermediate layer (fiber reinforced) and the inner layer (porous) form an acoustic impedance gradient to gradually attenuate the acoustic wave energy layer by layer.

[0018] In the functional surface layer of the present invention, the two materials, polystyrene and graphite-modified polystyrene, have good heat insulation performance, and the addition of graphite-modified polystyrene can further improve the thermal stability and conductivity of the materials, contributing to enhancing the overall weather resistance and fire resistance. As a nano-level filler, nano-silica can effectively enhance the mechanical properties and heat resistance of the materials, while improving the anti-aging performance of the materials. The combined use of ammonium polyphosphate and pentaerythritol can form an effective flame retardant system, reducing the burning rate and burning temperature of the materials and improving the fire resistance. In the intermediate layer, the short cut glass fibers and graft-modified glass fibers can significantly improve the mechanical properties and dimensional stability of the materials, and at the same time, the heat conductivity of the glass fibers also helps to evenly distribute heat and improve the heat insulation performance.

[0019] In the present invention, the intumescent flame retardant ammonium polyphosphate and pentaerythritol in the surface layer are compounded to form an expanded carbon layer (heat insulation and oxygen isolation) at high temperature and release incombustible gases to dilute oxygen; the compounding of the inorganic flame retardants magnesium hydroxide and aluminum hydroxide in the intermediate layer can decompose endothermically and release water vapor to dilute combustible gases, effectively improving the flame retardancy of the extruded board.

[0020] The inner layer material of the present invention uses a CO2 supercritical foaming agent to create a uniform microporous closed-cell structure (with tiny and evenly distributed pore diameters). The thermal conductivity of the gas in these closed cells is extremely low, effectively suppressing heat convection and conduction. The nano-sheet structure of montmorillonite coated with zinc oxide constructs a "labyrinth effect" in the matrix, extending the heat transfer path. The intercalated structure of montmorillonite further reduces the thermal conductivity of the material. As a layered silicate, when zinc oxide nanoparticles are evenly coated on the surface of montmorillonite, its ability to block the heat conduction path is further enhanced. The layered structure significantly reduces the heat conduction efficiency by increasing the tortuosity of the heat flow path. Zinc oxide itself has a low thermal conductivity, and after being compounded with montmorillonite, a multi-level barrier effect is formed. In addition, the graft-modified glass fibers form a three-dimensional network structure in the intermediate layer, reducing the continuity of the polymer matrix and inhibiting phonon conduction; the spatial complementarity between the layered barrier of montmorillonite-zinc oxide in the inner layer and the fiber network in the intermediate layer makes the heat have to bypass the double obstacles of the fiber network and the layered filler, thereby further enhancing the heat insulation performance.

[0021] At the microscopic level, zinc oxide forms a heterojunction on the surface of montmorillonite, improving the ultraviolet absorption efficiency; the organic-inorganic interface of the grafted fibers enhances the stress transfer. The fiber network in the intermediate layer and the montmorillonite sheets in the inner layer jointly form a hierarchical barrier structure, and the phosphate produced by the decomposition of the surface layer flame retardant and the fiber network in the intermediate layer jointly build a continuous fire barrier. The foamed structure in the inner layer reduces the convective heat loss through the closed-cell design. Therefore, the graft-modified glass fibers and zinc oxide-coated montmorillonite can achieve synergistic enhancement of performance.

[0022] In the present invention, a flexible organosilicon segment is formed on the surface of glass fiber grafted with octavinylsilsesquioxane, enhancing the interfacial bonding with the polystyrene matrix and reducing the reflection loss of sound waves at the interface. At the same time, the fiber network dissipates sound energy through friction, and the short-cut fibers (3-5 mm) can effectively disrupt the propagation of medium and high-frequency sound waves. Moreover, the nano-interlayer voids of montmorillonite and the piezoelectric effect of zinc oxide work together: the interlayer voids absorb low-frequency sound waves through viscous damping, and the microcurrent generated by zinc oxide under the sound wave pressure converts mechanical energy into heat energy. It forms a wide-band sound absorption coverage with the intermediate layer fiber network.

[0023] In terms of fire retardancy, after the silanized glass fiber is grafted with octavinylsilsesquioxane, it decomposes to form a Si-O-C cross-linked network at high temperature, which synergistically acts with the water vapor generated by the decomposition of magnesium hydroxide / aluminum in the intermediate layer to promote the formation of a dense carbon layer. The grafted organosilicon segment can improve the thermal stability of the carbon layer; while zinc oxide is converted to ZnO at high temperature, and together with the montmorillonite sheets, it constructs a physical barrier to delay the diffusion of combustible gases. The free radicals captured in the montmorillonite interlayer and the photocatalytic activity of ZnO synergistically inhibit the combustion chain reaction. In addition, in terms of low-temperature weather resistance, the hydroxyl groups on the surface of the glass fiber treated with silane coupling agent undergo free radical grafting with the vinyl groups of octavinylsilsesquioxane to form C-Si-O covalent bonds. The hydrophobicity of the fiber grafting layer reduces the frost heaving stress caused by water penetration. Detailed implementation mode

[0024] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention. It should be noted that the model of the graphite-modified polystyrene in the present invention is SEPS.

[0025] Embodiment 1 In this embodiment, a multi-layer composite extrusion board is provided, including a functional surface layer, an intermediate layer and an inner layer with a thickness ratio of 3:8:9; The functional surface layer is composed of the following raw materials in parts by weight: 50 parts of polystyrene, 30 parts of graphite-modified polystyrene, 5 parts of nano-silica, 10 parts of flame retardant, 1.5 parts of antioxidant and 3 parts of lubricant; The intermediate layer is composed of the following raw materials in parts by weight: 65 parts of polystyrene, 15 parts of short-cut glass fiber filaments, 6 parts of graft-modified glass fiber, 10 parts of flame retardant, 3 parts of coupling agent, 2 parts of foaming nucleating agent; The inner layer is composed of the following raw materials in parts by weight: 55 parts of polystyrene, 30 parts of CO2 supercritical foaming agent, 5 parts of zinc oxide-coated montmorillonite, 0.5 part of carbon nanotube and 2.5 parts of quaternary ammonium salt antistatic agent; Among them, the glass fiber is heated to 570 °C at a rate of 3.5 °C / min and held for 2.5 h to obtain pretreated glass fiber; silane coupling agent KH550, ethanol and water with a volume ratio of 1:19:2 are mixed, and the pH is adjusted to 4.5 with acetic acid; subsequently, the pretreated fiber is impregnated therein, ultrasonicated at 65 °C and 45 kHz for 35 min, then left standing for 23 h, and vacuum dried at 70 °C for 8 h to obtain silanized glass fiber; 2.5 g of octavinylsilsesquioxane is ultrasonically dispersed in 210 mL of ethanol, 0.15 g of benzoyl peroxide initiator is added, and magnetically stirred and dissolved to obtain a grafting solution; the silanized glass fiber is immersed therein, heated to 65 °C under nitrogen protection, stirred and reacted at 800 rpm for 6 h, controlling the dosage ratio of silanized glass fiber to grafting solution to be 1:22 g / mL. After the reaction, it is ultrasonically cleaned 4 times with ethanol and deionized water in sequence, and vacuum dried at 70 °C for 13 h to obtain graft-modified glass fiber; Among them, the preparation method of zinc oxide-coated montmorillonite includes: dissolving zinc acetate dihydrate in ethanol, adding sodium hydroxide to adjust the pH to 10, ultrasonically dispersing at 55 °C for 6 hours to obtain zinc oxide sol, mixing montmorillonite with zinc oxide sol, adding hydrazine hydrate solution, ultrasonically stirring at 75 °C for 6.5 hours, then reacting at 170 °C for 23 hours, filtering, washing and drying to obtain it; the weight part ratio of zinc acetate dihydrate: ethanol: montmorillonite and hydrazine hydrate solution is 15:40:2:2.5; Among them, the flame retardant in the functional surface layer includes ammonium polyphosphate and pentaerythritol with a weight part ratio of 2.5:5, the antioxidant is antioxidant 1010, and the lubricant is calcium stearate; the average length of the short cut glass fiber in the intermediate layer is 4 mm, the flame retardant includes magnesium hydroxide and aluminum hydroxide with a weight part ratio of 1:3.5, the silane coupling agent is silane coupling agent KH550, and the foaming nucleating agent is talc powder; the quaternary ammonium salt antistatic agent in the inner layer is octadecyltrimethylammonium chloride; The preparation method of this multi-layer composite extruded board includes the steps of: mixing the raw materials of the functional surface layer, intermediate layer and inner layer respectively, controlling the die head temperature to be 107 °C, using three-layer co-extrusion foaming to extrude prefabricated boards, controlling the roller temperature to be 85 °C, pressing the boards through a three-roll calender to make the board thickness 50 mm, and the calendering speed to extrusion speed ratio is 1:1.2; performing plasma treatment at a power of 5 kW and a speed of 3 m / min, slitting and then curing at a constant temperature of 60 °C for 24 h to obtain a multi-layer composite extruded board; among them, the temperature of the functional surface layer extruder: zone 1 is 190 °C, zone 2 is 200 °C, zone 3 is 210 °C; the temperature of the intermediate layer extruder: zone 1 is 180 °C, zone 2 is 195 °C, zone 3 is 205 °C; the temperature of the inner layer extruder: zone 1 is 175 °C, zone 2 is 185 °C, zone 3 is 195 °C; and the injection pressure of the inner layer foaming agent is 13 MPa.

[0026] Example 2 In this embodiment, a multi-layer composite extrusion board is provided, including a functional surface layer, an intermediate layer, and an inner layer with a thickness ratio of 14:35:42; The functional surface layer is composed of the following raw materials in parts by weight: 45 parts of polystyrene, 25 parts of graphite-modified polystyrene, 4 parts of nano-silica, 8 parts of flame retardant, 1 part of antioxidant, and 2 parts of lubricant; The intermediate layer is composed of the following raw materials in parts by weight: 60 parts of polystyrene, 14 parts of short glass fiber filaments, 5 parts of graft-modified glass fiber, 8 parts of flame retardant, 2 parts of coupling agent, and 1.5 parts of foaming nucleating agent; The inner layer is composed of the following raw materials in parts by weight: 50 parts of polystyrene, 25 parts of CO2 supercritical foaming agent, 4 parts of zinc oxide-coated montmorillonite, 0.4 part of carbon nanotube, and 2 parts of quaternary ammonium salt antistatic agent; Among them, the glass fiber is heated to 550 °C at a rate of 3 °C / min and kept warm for 2 h to obtain pretreated glass fiber; a mixture of silane coupling agent KH550, ethanol, and water with a volume ratio of 1:18:2 is mixed, and the pH is adjusted to 4 with acetic acid; then the pretreated fiber is impregnated therein, ultrasonic oscillation is carried out at 60 °C and 40 kHz for 30 min, then left standing for 22 h, and vacuum dried at 60 °C for 6 h to obtain silanized glass fiber; 2 g of octavinyl silsesquioxane is ultrasonically dispersed in 200 mL of ethanol, 0.1 g of benzoyl peroxide initiator is added, and magnetic stirring is carried out to dissolve to obtain a grafting solution; the silanized glass fiber is immersed therein, heated to 60 °C under nitrogen protection, and stirred and reacted at 700 rpm for 5 h, controlling the dosage ratio of silanized glass fiber to grafting solution to be 1:20 g / mL. After the reaction, it is ultrasonically cleaned 3 times with ethanol and deionized water in sequence, and vacuum dried at 60 °C for 12 h to obtain graft-modified glass fiber; Among them, the preparation method of zinc oxide-coated montmorillonite includes: dissolving zinc acetate dihydrate in ethanol, adding sodium hydroxide to adjust the pH to 9, ultrasonically dispersing at 50 °C for 5 hours to obtain zinc oxide sol, mixing montmorillonite with zinc oxide sol, adding hydrazine hydrate solution, ultrasonically stirring at 70 °C for 6 hours, then reacting at 165 °C for 22 hours, filtering, washing, and drying to obtain it; the weight part ratio of zinc acetate dihydrate: ethanol: montmorillonite and hydrazine hydrate solution is 10:30:1:1.5; Among them, the flame retardant in the functional surface layer includes ammonium polyphosphate and pentaerythritol with a weight part ratio of 2:4, the antioxidant is antioxidant 1010, and the lubricant is calcium stearate; the average length of the short glass fiber filaments in the intermediate layer is 3 mm, the flame retardant includes magnesium hydroxide and aluminum hydroxide with a weight part ratio of 1:3, the silane coupling agent is silane coupling agent KH550, and the foaming nucleating agent is talc powder; the quaternary ammonium salt antistatic agent in the inner layer is octadecyltrimethylammonium chloride; The preparation method of this multi-layer composite extruded board comprises the following steps: mixing the raw materials of the functional surface layer, the intermediate layer and the inner layer respectively, controlling the die head temperature at 105°C, using three-layer co-extrusion foaming to extrude a prefabricated board, controlling the roller temperature at 80°C, pressing the board through a three-roll calender to make the board thickness 50mm, and the ratio of the calendering speed to the extrusion speed is 1:1.2; performing plasma treatment at a power of 4kW and a speed of 2.5m / min, and after slitting, curing at a constant temperature of 55°C for 23h to obtain the multi-layer composite extruded board; wherein, the temperature of the functional surface layer extruder: zone 1 is 185°C, zone 2 is 195°C, zone 3 is 205°C; the temperature of the intermediate layer extruder: zone 1 is 175°C, zone 2 is 190°C, zone 3 is 200°C; the temperature of the inner layer extruder: zone 1 is 170°C, zone 2 is 180°C, zone 3 is 190°C; and the injection pressure of the inner layer foaming agent is 12MPa.

[0027] Example 3 In this example, a multi-layer composite extruded board is provided, which includes a functional surface layer, an intermediate layer and an inner layer with a thickness ratio of 16:45:48; The functional surface layer is composed of the following raw materials in parts by weight: 55 parts of polystyrene, 35 parts of graphite-modified polystyrene, 6 parts of nano-silica, 12 parts of flame retardant, 2 parts of antioxidant and 4 parts of lubricant; The intermediate layer is composed of the following raw materials in parts by weight: 70 parts of polystyrene, 16 parts of short glass fiber strands, 7 parts of graft-modified glass fiber, 12 parts of flame retardant, 4 parts of coupling agent, 2.5 parts of foaming nucleating agent; The inner layer is composed of the following raw materials in parts by weight: 60 parts of polystyrene, 35 parts of CO2 supercritical foaming agent, 6 parts of zinc oxide-coated montmorillonite, 0.6 part of carbon nanotube and 3 parts of quaternary ammonium salt antistatic agent; Among them, the glass fiber is heated to 600°C at a rate of 4°C / min and kept at this temperature for 3h to obtain pretreated glass fiber; mix silane coupling agent KH550, ethanol and water in a volume ratio of 1:20:2, and adjust the pH to 5 with acetic acid; then immerse the pretreated fiber in it, perform ultrasonic oscillation at 70°C and 50kHz for 40min, then let it stand for 24h, and dry it in vacuum at 80°C for 10h to obtain silanized glass fiber; ultrasonically disperse 3g of octavinylsilsesquioxane in 220mL of ethanol, add 0.2g of benzoyl peroxide initiator, and stir magnetically to dissolve to obtain a grafting solution; immerse the silanized glass fiber in it, heat it to 70°C under nitrogen protection, stir and react at 900rpm for 7h, control the dosage ratio of silanized glass fiber to the grafting solution to be 1:20g / mL, after the reaction is completed, ultrasonically clean it 5 times with ethanol and deionized water in turn, and dry it in vacuum at 80°C for 14h to obtain graft-modified glass fiber; Among them, the preparation method of zinc oxide-coated montmorillonite includes: dissolving zinc acetate dihydrate in ethanol, adding sodium hydroxide to adjust the pH to 11, ultrasonically dispersing at 60°C for 7 hours to obtain zinc oxide sol, mixing montmorillonite with the zinc oxide sol, adding hydrazine hydrate solution, ultrasonically stirring at 80°C for 7 hours, then reacting at 175°C for 24 hours, filtering, washing, and drying to obtain it; the weight ratio of zinc acetate dihydrate: ethanol: montmorillonite and hydrazine hydrate solution is 20:50:3:3.5; Among them, the flame retardant in the functional surface layer includes ammonium polyphosphate and pentaerythritol with a weight ratio of 3:6, the antioxidant is antioxidant 1010, and the lubricant is calcium stearate; the average length of the short cut glass fibers in the intermediate layer is 5 mm, the flame retardant includes magnesium hydroxide and aluminum hydroxide with a weight ratio of 1:4, the silane coupling agent is silane coupling agent KH550, and the foaming nucleating agent is talc powder; the quaternary ammonium salt antistatic agent in the inner layer is octadecyltrimethylammonium chloride; The preparation method of this multi-layer composite extrusion board includes the steps of: mixing the raw materials of the functional surface layer, intermediate layer and inner layer respectively, controlling the die head temperature at 110°C, using three-layer co-extrusion foaming to extrude prefabricated boards, controlling the roller temperature at 90°C, pressing the boards through a three-roll calender to make the board thickness 50 mm, and the ratio of the calendering speed to the extrusion speed is 1:1.2; performing plasma treatment at a power of 6 kW and a speed of 3.5 m / min, and thermally curing at 65°C for 25 h after slitting to obtain the multi-layer composite extrusion board; among them, the temperature of the functional surface layer extruder: zone 1 is 195°C, zone 2 is 205°C, zone 3 is 215°C; the temperature of the intermediate layer extruder: zone 1 is 185°C, zone 2 is 200°C, zone 3 is 210°C; the temperature of the inner layer extruder: zone 1 is 180°C, zone 2 is 190°C, zone 3 is 200°C; and the injection pressure of the inner layer foaming agent is 15 MPa.

[0028] Example 4 In this example, a multi-layer composite extrusion board is provided, including a functional surface layer, an intermediate layer and an inner layer with a thickness ratio of 14:45:42; The functional surface layer is composed of the following raw materials in parts by weight: 45 parts of polystyrene, 35 parts of graphite-modified polystyrene, 4 parts of nano-silica, 12 parts of flame retardant, 1 part of antioxidant and 4 parts of lubricant; The intermediate layer is composed of the following raw materials in parts by weight: 60 parts of polystyrene, 16 parts of short cut glass fibers, 5 parts of graft-modified glass fibers, 12 parts of flame retardant, 2 parts of coupling agent, 2.5 parts of foaming nucleating agent; The inner layer is composed of the following raw materials in parts by weight: 50 parts of polystyrene, 35 parts of CO2 supercritical foaming agent, 4 parts of zinc oxide-coated montmorillonite, 0.6 part of carbon nanotube and 2 parts of quaternary ammonium salt antistatic agent; Among them, the glass fiber was heated to 550 °C at a rate of 4 °C / min and held for 3 h to obtain pretreated glass fiber; silane coupling agent KH550, ethanol and water with a volume ratio of 1:18:2 were mixed, and the pH was adjusted to 5 with acetic acid; then the pretreated fiber was impregnated therein, sonicated at 60 °C and 50 kHz for 30 min, allowed to stand for 24 h, and vacuum dried at 60 °C for 10 h to obtain silanized glass fiber; 2 g of octavinylsilsesquioxane was ultrasonically dispersed in 220 mL of ethanol, 0.1 g of benzoyl peroxide initiator was added, and dissolved by magnetic stirring to obtain a grafting solution; the silanized glass fiber was immersed therein, heated to 70 °C under nitrogen protection, and stirred and reacted at 700 rpm for 7 h, controlling the dosage ratio of silanized glass fiber to grafting solution to be 1:20 g / mL. After the reaction, it was ultrasonically cleaned 5 times with ethanol and deionized water in sequence, and vacuum dried at 60 °C for 14 h to obtain graft-modified glass fiber; Among them, the preparation method of zinc oxide-coated montmorillonite includes: dissolving zinc acetate dihydrate in ethanol, adding sodium hydroxide to adjust the pH to 9, ultrasonically dispersing at 60 °C for 5 h to obtain zinc oxide sol, mixing montmorillonite with zinc oxide sol, adding hydrazine hydrate solution, ultrasonically stirring at 80 °C for 6 h, and then reacting at 175 °C for 22 h, followed by suction filtration, washing and drying to obtain; the weight part ratio of zinc acetate dihydrate: ethanol: montmorillonite and hydrazine hydrate solution is 20:30:1:3.5; Among them, the flame retardant in the functional surface layer includes ammonium polyphosphate and pentaerythritol with a weight part ratio of 2:6, the antioxidant is antioxidant 1010, and the lubricant is calcium stearate; the average length of the short cut glass fiber in the intermediate layer is 3 mm, the flame retardant includes magnesium hydroxide and aluminum hydroxide with a weight part ratio of 1:3, the silane coupling agent is silane coupling agent KH550, and the foaming nucleating agent is talc powder; the quaternary ammonium salt antistatic agent in the inner layer is octadecyltrimethylammonium chloride; The preparation method of this multi-layer composite extrusion board includes the steps of: mixing the raw materials of the functional surface layer, intermediate layer and inner layer respectively, controlling the die head temperature at 110 °C, using three-layer co-extrusion foaming to extrude a prefabricated board, controlling the roll temperature at 80 °C, pressing the board through a three-roll calender to make the board thickness 50 mm, and the calendering speed to extrusion speed ratio is 1:1.2; performing plasma treatment at a power of 6 kW and a speed of 2.5 m / min, and thermally curing at 65 °C for 23 h after slitting to obtain a multi-layer composite extrusion board; among them, the temperature of the functional surface layer extruder: zone 1 is 195 °C, zone 2 is 195 °C, zone 3 is 215 °C; the temperature of the intermediate layer extruder: zone 1 is 175 °C, zone 2 is 200 °C, zone 3 is 210 °C; the temperature of the inner layer extruder: zone 1 is 180 °C, zone 2 is 190 °C, zone 3 is 200 °C; and the injection pressure of the inner layer foaming agent is 12 MPa.

[0029] Comparative Example 1 Based on Example 1 with adjustments, the difference from Example 1 is that the graft-modified glass fiber is replaced by silanized glass fiber.

[0030] Comparative Example 2 Based on Example 1 with adjustments, the difference from Example 1 is that the graft-modified glass fiber is replaced by chopped glass fiber.

[0031] Comparative Example 3 Based on Example 1 with adjustments, the difference from Example 1 is that the graft-modified glass fiber is not added to the intermediate layer raw material.

[0032] Comparative Example 4 Based on Example 1 with adjustments, the difference from Example 1 is that the zinc oxide-coated montmorillonite is replaced by zinc oxide.

[0033] Comparative Example 5 Based on Example 1 with adjustments, the difference from Example 1 is that the zinc oxide-coated montmorillonite is replaced by montmorillonite.

[0034] Comparative Example 6 Based on Example 1 with adjustments, the difference from Example 1 is that the graft-modified glass fiber is not added to the inner layer raw material.

[0035] Test Example 1: The following tests were carried out on the multi-layer composite extruded boards prepared in the foregoing Examples 1-4 and Comparative Examples 1-6: 1. Thermal insulation: Tested with reference to GB / T 10294-2008 Guarded hot plate method to measure the thermal conductivity of the extruded board at an average temperature of 25°C; 2. Sound insulation: Tested with reference to GB / T 19889.3-2005 Laboratory measurement of airborne sound insulation to measure the sound insulation amount of the extruded board in the frequency band of 125 - 4000 Hz; 3. Flame retardancy: Tested with reference to GB / T 2406.2-2009; 4. Weather resistance: Maintained at -20°C for 12 h and at room temperature for 12 h, and cycled 30 times to evaluate the cracking of the extruded board. The cracking is divided into 5 grades, with Grade 1 having almost no cracking and Grade 5 having very serious cracking.

[0036] The results are shown in Table 1 below: Table 1

[0037] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-layer composite extrusion board, characterized in that, It includes a functional surface layer, an intermediate layer and an inner layer; The functional surface layer is composed of the following raw materials in parts by weight: 45-55 parts of polystyrene, 25-35 parts of graphite-modified polystyrene, 4-6 parts of nano-silica, 8-12 parts of flame retardant, 1-2 parts of antioxidant and 2-4 parts of lubricant; The intermediate layer is composed of the following raw materials in parts by weight: 60-70 parts of polystyrene, 14-16 parts of short glass fiber filaments, 5-7 parts of graft-modified glass fiber, 8-12 parts of flame retardant, 2-4 parts of coupling agent, 1.5-2.5 parts of foaming nucleating agent; The inner layer is composed of the following raw materials in parts by weight: 50-60 parts of polystyrene, 25-35 parts of CO2 supercritical foaming agent, 4-6 parts of zinc oxide-coated montmorillonite, 0.4-0.6 parts of carbon nanotube and 2-3 parts of quaternary ammonium salt antistatic agent.

2. The multi-layer composite extrusion board according to claim 1, wherein The thickness ratio of the functional surface layer, the intermediate layer and the inner layer is 14-16:35-45:42-48.

3. The multi-layer composite extrusion board according to claim 2, wherein The preparation method of the graft-modified glass fiber includes: ultrasonically dispersing 2-3 g of octavinylsilsesquioxane in 200-220 mL of ethanol, adding 0.1-0.2 g of benzoyl peroxide initiator, and magnetically stirring and dissolving to obtain a grafting solution; immersing the silanized glass fiber therein, heating to 60-70 °C under nitrogen protection, stirring and reacting at 700-900 rpm for 5-7 h, controlling the dosage ratio of the silanized glass fiber to the grafting solution to be 1:20-24 g / mL, after the reaction is completed, ultrasonically cleaning with ethanol and deionized water 3-5 times in sequence, and vacuum drying at 60-80 °C for 12-14 h to obtain the graft-modified glass fiber.

4. The multi-layer composite extrusion board according to claim 3, characterized in that, The preparation method of the silanized glass fiber includes: heating the glass fiber to 550-600 °C at 3-4 °C / min and holding for 2-3 h to obtain the pretreated glass fiber; mixing the silane coupling agent, ethanol and water with a volume ratio of 1:18-20:2, adjusting the pH to 4-5 with acetic acid; then impregnating the pretreated fiber therein, ultrasonically oscillating at 60-70 °C and 40-50 kHz for 30-40 min, standing for 22-24 h, and vacuum drying at 60-80 °C for 6-10 h to obtain the silanized glass fiber.

5. A multi-layer composite extrusion board according to claim 1, characterized in that, The preparation method of the zinc oxide-coated montmorillonite includes: dissolving zinc acetate dihydrate in ethanol, adding sodium hydroxide to adjust the pH to 9-11, ultrasonically dispersing at 50-60 °C for 5-7 h to obtain zinc oxide sol, mixing the montmorillonite with the zinc oxide sol, and adding a hydrazine hydrate solution, ultrasonically stirring at 70-80 °C for 6-7 h, and then reacting at 165-175 °C for 22-24 h, followed by suction filtration, washing and drying to obtain it.

6. The multi-layer composite extrusion board according to claim 5, characterized in that, The weight part ratio of the zinc acetate dihydrate: ethanol: montmorillonite and the hydrazine hydrate solution is 10-20:30-50:1-3:1.5-3.

5.

7. The multi-layer composite extrusion board according to claim 6, characterized in that, The flame retardant in the functional surface layer includes ammonium polyphosphate and pentaerythritol with a weight part ratio of 2-3:4-6, the antioxidant is antioxidant 1010, and the lubricant is calcium stearate.

8. The multi-layer composite extrusion board according to claim 1, characterized in that The average length of the chopped glass fibers in the intermediate layer is 3-5 mm. The flame retardant includes magnesium hydroxide and aluminum hydroxide with a weight ratio of 1:3-4. The silane coupling agent is silane coupling agent KH550, and the foaming nucleating agent is talc powder; the quaternary ammonium salt antistatic agent in the inner layer is octadecyltrimethylammonium chloride.

9. A method for preparing a multi-layer composite extrusion board according to any one of claims 1-8, characterized in that the steps It includes: Mix the raw materials of the functional surface layer, intermediate layer and inner layer respectively, control the die head temperature at 105-110°C, use a three-layer co-extrusion foaming process to extrude prefabricated plates, control the roll temperature at 80-90°C, press the plates through a three-roll calender to make the plate thickness 20-100 mm, and the calendering speed to extrusion speed ratio is 1:1.2; conduct plasma treatment at a power of 4-6 kW and a speed of 2.5-3.5 m / min, and after slitting, cure at a constant temperature of 55-65°C for 23-25 h to obtain the multi-layer composite extrusion board.

10. The preparation method of a multi-layer composite extrusion board according to claim 9, characterized in that, The temperature of the functional surface layer extruder: zone 1 is 185-195°C, zone 2 is 195-205°C, zone 3 is 205-215°C; the temperature of the intermediate layer extruder: zone 1 is 175-185°C, zone 2 is 190-200°C, zone 3 is 200-210°C; the temperature of the inner layer extruder: zone 1 is 170-180°C, zone 2 is 180-190°C, zone 3 is 190-200°C; and the injection pressure of the inner layer foaming agent is 12-15 MPa.

Images