Lightweight anti-radiation wood-plastic composite material and preparation method and co-extrusion equipment thereof

Abstract

The invention provides a light anti-radiation wood-plastic composite material as well as a preparation method and co-extrusion equipment thereof, belongs to the field of wood-plastic material preparation, and solves the problems of low preparation efficiency, insufficient anti-radiation performance and the like of an existing wood-plastic composite material. The material is formed by sequentially distributing a metal coating microbead blending modified surface co-extrusion layer, a superfine barium sulfate prefabricated master batch modified wood-plastic base material and a metal coating microbead modified polystyrene foam filling cavity from outside to inside. The method comprises the steps of wood-plastic granulation material preparation, wood-plastic base material forming, co-extrusion granulation material preparation, surface co-extrusion layer forming, polystyrene foam filling cavity forming, semi-finished product composite forming and post-processing forming. The co-extrusion equipment comprises a customized mold, a high-speed mixer, a flat double granulator, a first elevator, a main extruder, two injection machines, a co-extrusion device, a spiral side feeder, a second elevator and a mixing and granulating all-in-one machine. The composite material disclosed by the invention is high in preparation efficiency, stable in preparation process and excellent in anti-radiation performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of wood-plastic material preparation, and relates to a lightweight radiation-proof wood-plastic composite material, in particular to a lightweight radiation-proof wood-plastic composite material, a preparation method thereof, and a co-extrusion device. Background Art

[0002] The lightweight radiation-proof wood-plastic composite material is a high-performance material that combines wood fibers and a plastic matrix, and has received extensive attention in recent years in fields such as construction, medical treatment, and aerospace. Its background technology involves cross-innovation in material science, radiation protection, and processing technology. The following is an analysis of the key background technology.

[0003] Limitations of traditional wood-plastic composite materials: Insufficient radiation protection: It is difficult to be used in scenarios such as nuclear facilities and medical shielding. Contradiction between density and mechanical properties: Adding heavy metals (lead, barium) or minerals (hematite) can improve radiation protection, but it will cause a sharp increase in the material density (>3 g / cm³), losing the lightweight characteristics of WPC (the density of traditional WPC is 1.2 - 1.4 g / cm³). Interface compatibility problem: The polarity difference between wood fibers and plastics is large, and simple blending easily leads to interface defects, affecting the mechanical strength and the dispersion of radiation-proof fillers.

[0004] Therefore, the key bottlenecks of the lightweight radiation-proof wood-plastic composite material (WPC) lie in filler selection, structural design, and equipment technology. Based on this, we propose a lightweight radiation-proof wood-plastic composite material, a preparation method thereof, and a co-extrusion device, which have high composite preparation efficiency, stable roll pressing output, and excellent product performance. Summary of the Invention

[0005] The purpose of the present invention is to address the above problems existing in the prior art, and propose a lightweight radiation-proof wood-plastic composite material, a preparation method thereof, and a co-extrusion device. The technical problem to be solved by this invention is: how to achieve efficient and stable composite preparation and roll pressing output of the lightweight radiation-proof wood-plastic composite material, while ensuring that the prepared product has excellent properties such as radiation protection, low density, and lightweight.

[0006] The purpose of the present invention can be achieved by the following technical solutions: This lightweight radiation-proof wood-plastic composite material is composed of a metal-coated microbead blend-modified surface co-extrusion layer, an ultrafine barium sulfate prefabricated masterbatch-modified wood-plastic substrate, and a metal-coated microbead-modified foaming agent filling cavity, which are distributed in sequence from the outside to the inside. Multiple groups of metal-coated microbead-modified foaming agent filling cavities are arranged in parallel in the ultrafine barium sulfate prefabricated masterbatch-modified wood-plastic substrate; The material density of the metal-coated microbead blend-modified surface co-extrusion layer is not greater than 0.90 g / cm 3 ; the density of the metal-coated microbead-modified foaming agent filling cavity after curing is not greater than 0.80 g / cm 3; The density of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate is not greater than 1.35 g / cm 3 ; The metal-coated microsphere blended modified surface co-extrusion layer, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate, and the metal-coated microsphere modified foaming glue filled cavity cooperate to prevent radiation; the density of the lightweight radiation-proof wood-plastic composite material is not greater than 1.20 g / cm 3 , and the lead equivalent to X-rays is 1.0 - 1.7 mmPb / c.

[0007] With the above scheme, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microsphere blended modified surface co-extrusion layer cooperate to prevent radiation, and the overall density of the prepared wood-plastic composite material is lower than 1.35 g / cm 3 When it can meet the standard requirements of medical radiation-proof building materials.

[0008] The ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate is prepared by compounding raw materials with the following mass ratios: biomass fiber 40% - 65%, ultrafine barium sulfate prefabricated masterbatch 20% - 50%, plastic matrix 5% - 25%, interfacial compatibilizer 2% - 10%, lubricant 0.5% - 5%; The ultrafine barium sulfate prefabricated masterbatch is prepared by compounding raw materials with the following mass ratios: ultrafine barium sulfate of 800 mesh and above 30% - 60%, coupling agent 3% - 8%, lubricating dispersant 1.5% - 5.0%, surfactant 0.5% - 2%, plastic matrix 35% - 55%; The metal-coated microsphere modified foaming glue filled cavity is prepared from raw materials with the following mass ratios: moisture-curing polyurethane foaming glue 60% - 85%, metal-coated microspheres 15% - 40%; The metal-coated microsphere blended modified surface co-extrusion layer is prepared by compounding raw materials with the following mass ratios: metal-coated microspheres 4% - 10%, plastic matrix 40% - 80%, ionomer 4% - 20%, functional filler 5% - 30%.

[0009] The plastic matrix in the ultrafine barium sulfate prefabricated masterbatch, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate, and the metal-coated microsphere blended modified surface co-extrusion layer is at least one of polyethylene, polypropylene, polyvinyl chloride, and polystyrene; The metal-coated microspheres in the metal-coated microsphere modified foaming glue filled cavity and the metal-coated microsphere blended modified surface co-extrusion layer are based on fly ash hollow spheres, and at least one of lead, copper, aluminum, iron, or tungsten metals is deposited and coated on the surface of the microspheres by magnetron sputtering technology. The particle size of the metal-coated microspheres is 0.5 - 30 μm, the thickness of the metal coating of the metal-coated microspheres is not less than 0.1 μm, and the bulk density is not greater than 0.85 g / cm 3 .

[0010] The coupling agent in the ultrafine barium sulfate prefabricated masterbatch is at least one of silane, titanate, and aluminate coupling agents; the lubricating dispersant is at least one of zinc stearate, calcium stearate, distilled monoglyceride stearate, pentaerythritol stearate, hyperbranched polyester, and hyperbranched polyamide; the surfactant is at least one of oleic acid, lauric acid, white oil, and mineral oil.

[0011] The biomass fiber in the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate is at least one of wood, bamboo, cotton, hemp, rice husk, wheat straw, soybean hull, oil-tea fruit shell, coffee grounds, peanut shell, and coconut shell fiber; the interfacial compatibilizer is at least one of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, glycidyl methacrylate grafted polyethylene, titanate, aluminate, and silane coupling agents; the lubricant is at least one of PE wax, stearic acid, calcium stearate, zinc stearate, oxidized polyethylene, and ethylene bis-stearamide; The ionomer in the metal-coated microbead blend modified surface co-extrusion layer is at least one of sodium ion polymer, zinc ion polymer, and lithium sodium ion polymer; the functional filler is at least one of toughening modification, wear resistance modification, anti-slip modification, anti-aging modification, and flame retardant modification fillers; the functional filler imparts any one of high impact toughness, ultraviolet reflection, infrared reflection, anti-slip, flame retardant, wear resistance, and scratch resistance to the surface co-extrusion layer. For the various functions imparted by the functional filler to the surface co-extrusion layer, the raw materials used are all publicly available prior art and commercially available raw materials.

[0012] Adopting the above scheme, the ultrafine barium sulfate prefabricated masterbatch effectively improves the dispersion uniformity of barium sulfate in the wood-plastic matrix. Compared with direct mixing, the barium sulfate usage of the same-effect product can be reduced by more than 30%; the metal-coated microbeads in the metal-coated microbead blend modified surface co-extrusion layer can cause the rays entering the sphere to be repeatedly refracted and absorbed, and endowing the co-extrusion layer with excellent radiation protection performance with a filling mass ratio of less than 10%.

[0013] The preparation method of this lightweight radiation-proof wood-plastic composite material is as follows: S1. Prepare wood-plastic pellets. Inject the raw materials of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate: biomass fiber, ultrafine barium sulfate prefabricated masterbatch, plastic matrix, interfacial compatibilizer, and lubricant according to the ratio into a high-speed mixer for uniform mixing to obtain a mixture, and then introduce the mixture into a flat double granulator to make wood-plastic pellets; S2. Form the wood-plastic substrate. Introduce the wood-plastic pellets prepared in S1 into the main extruder for plasticization and melting, and then transport them to the wood-plastic substrate forming part of a customized mold to form an ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate; S3. Prepare the co-extrusion granulated material by blending and modifying the raw materials of the surface co-extrusion layer with metal-coated microbeads: plastic matrix, ionomer, and functional additives, and first make the co-extrusion granulated material by a mixing and granulating integrated machine; S4. Surface co-extrusion layer forming: Introduce the co-extrusion granulated material prepared in S3 into the high-shear kneading section of the co-extrusion device to complete plasticization, melting, and blending, forming the front melt. Subsequently, inject the metal-coated microbeads into the low-shear mixing section of the co-extrusion device in a spiral side-feeding form to mix with the front melt. After the metal-coated microbeads are evenly dispersed in the melt, enter the uniform feeding section of the co-extrusion device and be transported to the surface co-extrusion plastic forming section of the customized mold to form a metal-coated microbead blended and modified surface co-extrusion layer; S5. Foaming adhesive filling cavity forming: The raw materials for filling the cavity with metal-coated microbead modified foaming adhesive: metal-coated microbeads and moisture-curing polyurethane foaming adhesive are respectively introduced into the modified foaming adhesive forming section of the customized mold through two different high-temperature resistant polytetrafluoroethylene tubes by two injection machines to form a metal-coated microbead modified foaming adhesive filling cavity; S6. Wood-plastic composite semi-finished product composite forming: The ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microbead blended and modified surface co-extrusion layer are first compounded in the detachable straight section mold of the customized mold, and then compounded with the metal-coated microbead modified foaming adhesive filling cavity at the customized die orifice of the customized mold to form a wood-plastic composite semi-finished product; S7. Post-processing forming of wood-plastic composite: The wood-plastic composite semi-finished product finally undergoes surface embossing, cooling and shaping, grinding and wire drawing, fixed-length cutting, and stacking and standing to prepare a lightweight radiation-proof wood-plastic composite.

[0014] In S5, the metal-coated microbeads enter the customized mold through a polytetrafluoroethylene tube with high-speed and high-humidity air as the carrier, and the moisture-curing polyurethane foaming adhesive enters the customized mold in a high-pressure injection form through a polytetrafluoroethylene tube. The metal-coated microbeads and the moisture-curing polyurethane foaming adhesive come into contact and are mixed evenly, and the moisture in the high-humidity air promotes the curing and shaping of the moisture-curing polyurethane foaming adhesive.

[0015] The co-extrusion equipment for this lightweight radiation-proof wood-plastic composite includes a customized mold, a high-speed mixer, a twin-screw extruder for granulation, a first elevator, a main extruder, two injection machines, a co-extrusion device, a spiral side-feeding machine, a second elevator, and a mixing and granulating integrated machine. The main extruder and the co-extrusion device are connected to the left and right sides of the customized mold. The high-speed mixer, the twin-screw extruder for granulation, and the first elevator are connected in sequence by pipelines, and there is a pipeline connection between the first elevator and the main extruder. The mixing and granulating integrated machine is located at the rear of the customized mold. The mixing and granulating integrated machine, the second elevator, and the co-extrusion device are connected in sequence by pipelines. The spiral side-feeding machine is arranged above the co-extrusion device, and there is a pipeline connection between the spiral side-feeding machine and the co-extrusion device. The two injection machines are located in front of the customized mold, and both of the two injection machines are connected to the customized mold through polytetrafluoroethylene tubes.

[0016] Working principle of the present invention: The raw materials for modifying the wood-plastic substrate with ultrafine barium sulfate prefabricated masterbatch, namely biomass fiber, ultrafine barium sulfate prefabricated masterbatch, plastic matrix, interfacial compatibilizer and lubricant, are injected into a high-speed mixer according to the ratio for uniform mixing to obtain a mixture. The mixture is introduced into a twin-screw pelletizer to form wood-plastic pellets; The prepared wood-plastic pellets are introduced into a main extruder through a first elevator for plasticization and melting, and then transported to a customized mold to form a wood-plastic substrate modified with ultrafine barium sulfate prefabricated masterbatch; The raw materials for the metal-coated bead co-blended modified surface co-extrusion layer, namely plastic matrix, ionomer and functional filler, are first made into co-extrusion pellets by a mixing and pelletizing integrated machine; It enters the co-extrusion device through a second elevator to complete plasticization, melting and blending to form a front melt. Subsequently, the metal-coated beads are injected into the co-extrusion device through a spiral side feeder to be mixed with the front melt. After the metal-coated beads are uniformly dispersed in the melt, it is transported to a customized mold to form a metal-coated bead co-blended modified surface co-extrusion layer; The raw materials for the metal-coated bead modified foaming adhesive filled cavity, namely metal-coated beads and moisture-curing polyurethane foaming adhesive, are respectively introduced into a customized mold through two injection machines by two different high-temperature resistant polytetrafluoroethylene tubes to form a metal-coated bead modified foaming adhesive filled cavity; The wood-plastic substrate modified with ultrafine barium sulfate prefabricated masterbatch and the metal-coated bead co-blended modified surface co-extrusion layer are first compounded in a customized mold, and then compounded with the metal-coated bead modified foaming adhesive filled cavity in the customized mold to form a semi-finished wood-plastic composite material; Finally, the semi-finished wood-plastic composite material undergoes surface embossing, cooling and shaping, grinding and wire drawing, fixed-length cutting and stacking and standing to prepare a lightweight radiation-proof wood-plastic composite material.

[0017] The customized mold includes a double-output speed reducer, a customized lower mold, a wood-plastic substrate forming part, a surface co-extruded plastic forming part, a modified foaming adhesive forming part and a guiding forming component. Composite motors are arranged at both ends of the double-output speed reducer and are in transmission connection with it. Two symmetrically arranged extrusion rollers are rotatably arranged inside the customized lower mold. The two output shafts of the double-output speed reducer are respectively in transmission connection with the extrusion rollers on the same side. The customized upper mold is detachably arranged at the upper end of the customized lower mold. Main feed port sections are arranged on both the left and right sides between the customized upper mold and the customized lower mold. A number of adjusting baffle plates are arranged in the middle of the customized lower mold and extend into the inside of the customized lower mold. A detachable straight section mold is slidably arranged at the lower end of the customized lower mold. A handle is arranged on the front side of the detachable straight section mold. Two rows of left-right symmetrically arranged guide wheels are arranged at the lower end of the detachable straight section mold. A number of temperature sensors are arranged on the detachable straight section mold. A customized die is detachably arranged at the lower end of the detachable straight section mold.

[0018] With the above structure, the double-output speed reducer, the customized lower die, and the composite motor are placed on the storage platform. According to the requirements of the finished product, the heights of several adjustable blanking plates are adjusted to adjust the thickness of the output material of the customized lower die. A detachable straight section die is slidably arranged at the lower end of the customized lower die, and a detachable straight section die with a corresponding size can be replaced according to needs. The handle is used to pull out and slide the detachable straight section die in and out of the lower end of the customized lower die for disassembly. The guide wheel is used to abut against the storage platform to facilitate the pulling out and placing of the detachable straight section die. The output shaft of the composite motor drives the input shaft of the double-output speed reducer on the same side to rotate, so that the two output shafts of the double-output speed reducer respectively drive the extrusion rollers on the same side to rotate synchronously and reversely inside the customized lower die. The ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-plated microbead co-mixed modified surface co-extrusion layer respectively enter between the customized upper die and the customized lower die from the main feed port section, and are conveyed downward by the extrusion rollers to the detachable straight section die, so that the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-plated microbead co-mixed modified surface co-extrusion layer are compounded. After compounding, they enter the customized die orifice. The metal-plated microbead modified foaming glue filling cavity enters the customized die orifice for compounding to form a wood-plastic composite semi-finished product, and then enters the guiding and forming assembly for roll pressing and output.

[0019] The customized die orifice includes a die orifice main body, which is detachably arranged at the lower end of the detachable straight section die, and the die orifice main body is communicated with the detachable straight section die. A side feed port section is arranged on the right side of the die orifice main body, and a composite outlet section is arranged at the lower part of the die orifice main body.

[0020] With the above structure, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-plated microbead co-mixed modified surface co-extrusion layer are compounded and enter the die orifice main body. The metal-plated microbead modified foaming glue filling cavity enters the die orifice main body from the side feed port section and is compounded with the composite body of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-plated microbead co-mixed modified surface co-extrusion layer to form a wood-plastic composite semi-finished product, and then is output downward from the composite outlet section.

[0021] The wood-plastic substrate forming part is connected to the discharge end of the main extruder. The wood-plastic substrate forming part is connected and abuts against the main feed port section on the left side. The surface co-extrusion plastic forming part is connected and abuts against the main feed port section on the right side. The modified foaming glue forming part and the guiding and forming assembly are both arranged above the surface co-extrusion plastic forming part. The modified foaming glue forming part is connected and abuts against the side feed port section. The wood-plastic substrate forming part and the surface co-extrusion plastic forming part have the same structure, and the wood-plastic substrate forming part, the surface co-extrusion plastic forming part, and the modified foaming glue forming part are all T-shaped extrusion die heads.

[0022] With the above structure, the main extruder transports the raw materials of the modified wood-plastic base material with ultrafine barium sulfate prefabricated masterbatch to the wood-plastic base material forming section. After forming, it is injected into the main feed port section on the left. The raw materials of the surface co-extrusion layer modified by blending with metal-coated microbeads are injected into the surface co-extrusion plastic forming section. After forming, it is injected into the main feed port section on the right. The raw materials of the modified foaming adhesive filled cavity with metal-coated microbeads are injected into the modified foaming adhesive forming section. After forming, it is injected into the side feed port section. The T-shaped extrusion die head is used for injection molding.

[0023] The guiding and forming assembly is located below the customized die. The guiding and forming assembly includes a guiding frame. A first roller, a second roller, and a third roller are sequentially rotatably arranged on the guiding frame from left to right. A guiding motor is fixed to the side of the guiding frame. The output shaft of the guiding motor is fixedly connected to the rotating shaft of the second roller. The composite outlet section is located between the first roller and the second roller.

[0024] With the above structure, after the composite of the modified foaming adhesive filled cavity with metal-coated microbeads, the modified wood-plastic base material with ultrafine barium sulfate prefabricated masterbatch, and the surface co-extrusion layer modified by blending with metal-coated microbeads is compounded, a semi-finished wood-plastic composite material is formed. The semi-finished wood-plastic composite material is output downward from the composite outlet section, first enters between the first roller and the second roller, and then enters between the second roller and the third roller. The output shaft of the guiding motor drives the rotating shaft of the second roller to rotate, stably roller-pressing and transporting the semi-finished wood-plastic composite material.

[0025] The mixing and granulating integrated machine includes a granulator main body. A discharge valve one and a discharge motor one are fixed above the granulator main body. The output shafts of the discharge valve one and the discharge motor one are in transmission connection. A mixing tank one is fixed to the upper end of the discharge valve one. A mixing motor one and a feed hopper one connected thereto are fixed to the upper end of the mixing tank one. A feeding rod is rotatably arranged inside the mixing tank one. The feeding rod is in transmission connection with the output shaft of the mixing motor one. A spiral discharge rod is fixed to the lower end of the feeding rod.

[0026] With the above structure, the raw materials of the surface co-extrusion layer modified by blending with metal-coated microbeads: plastic matrix, ionic polymer, and functional fillers are injected into the mixing tank one via the feed hopper one. The output shaft of the mixing motor one drives the feeding rod to rotate inside the mixing tank one. The feeding rod drives the spiral discharge rod to rotate. The feeding rod stably mixes the raw materials. After mixing, the spiral discharge rod injects the mixed raw materials into the discharge valve one, completing discharging while mixing. The output shaft of the discharge motor one drives the discharge valve one to work, injecting the mixed raw materials into the granulator main body for granulation, obtaining co-extrusion granulated materials, and then entering the co-extrusion device through the second elevator.

[0027] The co-extrusion device includes a number of support frames. A co-extrusion twin-screw assembly is provided on the number of support frames. A synchronous reverse double-output member and a granulation motor are fixed on the rightmost support frame. The output shaft of the granulation motor is drivingly connected to the input shaft of the synchronous reverse double-output member. The two output shafts of the synchronous reverse double-output member are drivingly connected to the co-extrusion twin-screw assembly. A discharge valve II and a discharge motor II are fixed on the co-extrusion twin-screw assembly. The output shaft of the discharge valve II is drivingly connected to the output shaft of the discharge motor II. A feed hopper II communicating therewith is provided at the upper end of the discharge valve II. A discharge die is provided at the discharge end of the co-extrusion twin-screw assembly. The discharge die is in contact connection with the surface co-extrusion plastic forming part. A number of temperature controllers are provided outside the co-extrusion twin-screw assembly.

[0028] With the above structure, the co-extrusion granulation material of the metal-coated microbead co-blended modified surface co-extrusion layer is injected into the feed hopper II through the second elevator. The output shaft of the discharge motor II drives the discharge valve II to work, and injects the co-extrusion granulation material into the co-extrusion twin-screw assembly. The two output shafts of the synchronous reverse double-output member drive the co-extrusion twin-screw assembly to work for plasticization, melting and blending. A number of temperature controllers control the temperature to ensure the quality of plasticization, melting and blending, and form a front melt. Subsequently, the metal-coated microbeads are injected into the co-extrusion device through a spiral side feeder to be mixed with the front melt. After the metal-coated microbeads are evenly dispersed in the melt, they are transmitted from the discharge die to the surface co-extrusion plastic forming part.

[0029] The co-extrusion twin-screw assembly includes two co-extrusion pipes that are detachably assembled up and down. Two co-extrusion screws are rotatably provided between the two co-extrusion pipes. The co-extrusion screws are drivingly connected to the two output shafts of the synchronous reverse double-output member. The co-extrusion screws are successively provided with a guide thread, a high-shear thread I, a high-shear thread II, a high-shear thread III, a low-shear thread and a uniform feeding thread from right to left. The co-extrusion twin-screw assembly is successively provided with a feeding area, a high-shear mixing section, a low-shear mixing section and a uniform feeding section from right to left. The discharge valve II and the guide thread are located in the feeding area. The high-shear thread I, the high-shear thread II and the high-shear thread III are located in the high-shear mixing section. The low-shear thread is located in the low-shear mixing section. The uniform feeding thread is located in the uniform feeding section; The support frames, the surface co-extrusion plastic forming part and the modified foaming glue forming part are all rotatably provided with feeding rollers.

[0030] With the above structure, the two output shafts of the synchronous reverse dual output parts drive the two co-extrusion screws to rotate synchronously in the opposite direction, and the co-extruded granulated material of the metal-coated microbeads blended and modified surface co-extrusion layer enters the two co-extrusion tubes, and successively enters the injection area, the high shear mixing section, the low shear mixing section and the uniform feeding section, that is, the guide thread stably transports it, and the high shear thread one, the high shear thread two, and the high shear thread three perform stable high shear mixing to achieve rapid melting and uniform mixing of the plastic matrix, the ion polymer and the functional additives, the low shear thread realizes uniform dispersion of the metal-coated microbeads in the front melt, and ensures that the spherical hollow microbeads are not squeezed and crushed, and the uniform feeding thread realizes uniform and quantitative transmission of the composite melt of the plastic matrix, the ion polymer, the functional additive and the metal-coated microbeads.

[0031] The spiral side feeder includes a mounting plate, which is fixed on the upper ends of several support frames, and three output shaft boxes are fixed on the mounting plate, and a feeding motor is fixed on the three output shaft boxes, and the output shaft of the feeding motor is drivingly connected to the input shaft of the three output shaft boxes, and a feeding pipe is fixed on the three output shaft boxes, and the discharge end of the feeding pipe is provided with a discharge pipe, and the discharge pipe is connected above the co-extrusion pipe of the low shear mixing section, and two feeding screws are provided for internal rotation of the feeding pipe, and the feeding screws are drivingly connected to two synchronous and reverse output shafts on the lower side of the three output shaft boxes, and a mixing tank 2 connected thereto is provided at the upper end of the feeding pipe, and another output shaft of the three output shaft boxes extends into the interior of the mixing tank 2, and a mixing rack rod 2 is fixed on another output shaft of the three output shaft boxes, and a mixing motor 2 is fixed on the mixing tank 2, and a mixing rack rod 1 is provided for internal rotation of the mixing tank 2, and the output shaft of the mixing motor 2 is drivingly connected to the mixing rack rod 1, and a feeding pipe is provided at the upper end of the mixing tank 2.

[0032] By adopting the above structure, the metal-coated microbeads are injected into the mixing tank 2 through the feeding pipe, the output shaft of the mixing motor 2 drives the mixing rack rod 1 to rotate inside the mixing tank 2, and the metal-coated microbeads are stably transferred, the output shaft of the feeding motor drives the input shaft of the three-output shaft box to rotate, and the other output shaft of the three-output shaft box drives the mixing rack rod 2 to rotate for stable transfer, and the two synchronously reversed output shafts on the lower side of the three-output shaft box drive the feeding screw to rotate synchronously in the opposite direction inside the feeding pipe, and the metal-coated microbeads are uniformly and quantitatively introduced into the discharge pipe, thereby being injected into the co-extrusion pipe of the low shear mixing section, mixed with the front melt, and after the metal-coated microbeads are evenly dispersed in the melt, they are transmitted from the discharge die to the surface co-extrusion plastic molding section.

[0033] The filling machine includes a filling vehicle body. There is a vehicle handle above the rear side of the filling vehicle body. A feeding pump is fixed on the filling vehicle body. An inclined extrusion pipe is also fixed on the filling vehicle body. The lower discharging end of the extrusion pipe is provided with a discharging joint. The upper end of the extrusion pipe is fixed with a feeding hopper. A filling motor is fixed on the feeding hopper. A sealing extrusion roller is fixed on the output shaft of the filling motor. The sealing extrusion roller is rotatably arranged inside the extrusion pipe. The output end of the feeding pump is connected to the extrusion pipe through a pipeline. The discharging joints of two filling machines are both connected to the feeding end of the modified foaming glue forming part through a polytetrafluoroethylene pipe.

[0034] With the above structure, the raw materials for filling the cavity of the metal-coated microbead modified foaming glue, namely metal-coated microbeads and moisture-curing polyurethane foaming glue, are respectively added into two filling machines, or poured into the feeding hopper or injected into the inside of the extrusion pipe through the feeding pump. The output shaft of the filling motor drives the sealing extrusion roller to rotate inside the extrusion pipe, and the materials are led out through the discharging joint. The metal-coated microbeads enter the modified foaming glue forming part through the polytetrafluoroethylene pipe with high-speed and high-humidity air as the carrier. The moisture-curing polyurethane foaming glue enters the modified foaming glue forming part in the form of high-pressure injection through the polytetrafluoroethylene pipe. The metal-coated microbeads and the moisture-curing polyurethane foaming glue contact and mix evenly at the die orifice of the modified foaming glue forming part. The moisture in the high-humidity air promotes the curing and shaping of the moisture-curing polyurethane foaming glue.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This lightweight radiation-proof wood-plastic composite material can meet the requirements of medical radiation-proof building materials standards. It has synergistic radiation protection by the metal-coated microbead co-blended modified surface co-extrusion layer, the ultra-fine barium sulfate prefabricated masterbatch modified wood-plastic substrate, and the metal-coated microbead modified foaming glue filling cavity. It has a small density, is lightweight, and has a good radiation protection effect.

[0036] 2. The co-extrusion equipment of the present invention cooperates with a high-speed mixer, a flat double granulator, a first elevator, and a main extruder, and then cooperates with a wood-plastic substrate forming part to achieve the rapid and efficient preparation of an ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate; through a mixing and granulating all-in-one machine, a second elevator, and a co-extrusion device, and the cooperation of the co-extrusion device and a spiral side feeder, and then cooperating with a surface co-extruded plastic forming part, the rapid and efficient preparation of a metal-coated microbead blended modified surface co-extruded layer is achieved; through two injection machines and a modified foaming glue forming part, the rapid and efficient preparation of a metal-coated microbead modified foaming glue filling cavity is achieved; through a customized mold, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microbead blended modified surface co-extruded layer are quickly compounded, and then the metal-coated microbead modified foaming glue filling cavity and the composite of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microbead blended modified surface co-extruded layer are compounded to achieve the stable and efficient preparation of a semi-finished wood-plastic composite material; through the cooperation of a guiding forming component and a customized die, stable roll pressing output is achieved, and then cooperating with the modified foaming glue forming part, the surface co-extruded plastic forming part, and a support frame, stable output is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a front-side three-dimensional structural schematic diagram of the equipment layout in the present invention.

[0038] Figure 2 It is a front-side three-dimensional structural schematic diagram of the equipment layout in the present invention.

[0039] Figure 3 It is a three-dimensional structural schematic diagram of the customized mold in the present invention.

[0040] Figure 4 It is a partial upper-side three-dimensional structural schematic diagram of the customized mold in the present invention.

[0041] Figure 5 It is a partial lower-side three-dimensional structural schematic diagram of the customized mold in the present invention.

[0042] Figure 6 It is a structural schematic diagram of some components of the customized mold in the present invention.

[0043] Figure 7 It is a structural schematic diagram of some equipment in the present invention.

[0044] Figure 8 It is a structural schematic diagram of the mixing and granulating all-in-one machine in the present invention.

[0045] Figure 9 It is a structural schematic diagram of the co-extrusion device in the present invention.

[0046] Figure 10 It is a structural schematic diagram of the co-extrusion twin-screw assembly in the present invention.

[0047] Figure 11 It is a schematic structural diagram of the spiral side feeder in the present invention.

[0048] Figure 12 It is a schematic structural diagram of the injection machine in the present invention.

[0049] Figure 13 It is a schematic process flow diagram of the preparation method in the present invention.

[0050] Figure 14 It is a schematic structural diagram of the lightweight radiation-proof wood-plastic composite material in the present invention.

[0051] In the figure, 1. Customized mold; 2. High-speed mixer; 3. Parallel twin pelletizer; 4. First elevator; 5. Main extruder; 6. Injection machine; 7. Surface co-extrusion plastic molding part; 8. Co-extrusion device; 9. Spiral side feeder; 10. Second elevator; 11. Mixing and pelletizing integrated machine; 12. Modified foaming glue molding part; 13. Composite motor; 14. Double-output reducer; 15. Customized mold body; 16. Guide forming component; 17. Customized upper mold; 18. Extrusion roller; 19. Adjusting baffle; 20. Customized die; 21. Customized lower mold; 22. Main feed port section; 23. Handle; 24. Temperature sensor; 25. Side feed port section; 26. Die body; 27. Composite outlet section; 28. Removable straight section mold; 29. Guide wheel; 30. First roller; 31. Second roller; 32. Guide frame; 33. Third roller; 34. Guide motor; 35. Feeding hopper 1; 36. Mixing motor 1; 37. Mixing tank 1; 38. Stirring rod; 39. Spiral discharge rod; 40. Discharge valve 1; 41. Discharge motor 1; 42. Pelletizer body; 43. Discharge die; 44. Support frame; 45. Temperature controller; 46. Co-extrusion twin-screw component; 47. Feeding hopper 2; 48. Discharge valve 2; 49. Discharge motor 2; 50. Synchronous reverse double-output part; 51. Pelletizing motor; 52. Co-extrusion pipe; 53. Uniform feeding thread; 54. Low-shear thread; 55. High-shear thread 3; 56. High-shear thread 2; 57. High-shear thread 1; 58. Guide feeding thread; 59. Co-extrusion screw; 60. High-shear internal mixer part; 61. Low-shear mixing part; 62. Uniform feeding part; 63. Feeding motor; 64. Mixing motor 2; 65. Mixing tank 2; 66. Feeding pipe; 67. Mixing rack bar 1; 68. Mixing rack bar 2; 69. Installation plate; 70. Discharge pipe; 71. Feeding pipe; 72. Feeding screw; 73. Three-output shaft box; 74. Handlebar; 75. Injection machine body; 76. Feeding pump; 77. Discharge joint; 78. Extrusion pipe; 79. Feeding hopper; 80. Injection motor; a. Metal-coated microsphere modified foaming glue filling cavity; b. Ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate; c. Metal-coated microsphere co-blended modified surface co-extrusion layer. Specific embodiments

[0052] The following are specific embodiments of the present invention. In combination with the accompanying drawings, the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0053] In the present invention, by adjusting the components in the lightweight radiation-proof wood-plastic composite material, namely the metal-coated microbead blended modified surface co-extrusion layer, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate, and the metal-coated microbead modified foaming glue filling cavity, embodiments 1-9 and comparative examples 1-3 are formed, and the corresponding composite materials are prepared. In addition, the raw materials used in the present invention are all raw materials that can be purchased on the market and developed by the company.

[0054] Embodiment 1 The lightweight radiation-proof wood-plastic composite material, its structural schematic diagram is as Figure 14 shown, and it is composed of a metal-coated microbead blended modified surface co-extrusion layer c, an ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate b, and a metal-coated microbead modified foaming glue filling cavity a, which are distributed in sequence from the outside to the inside.

[0055] The metal-coated microbead blended modified surface co-extrusion layer, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate, and the metal-coated microbead modified foaming glue filling cavity cooperate to prevent radiation. The density of the lightweight radiation-proof wood-plastic composite material is 1.20 g / cm 3 , and the lead equivalent to X-rays is 1.5 mmPb / c.

[0056] The material density of the metal-coated microbead blended modified surface co-extrusion layer is not greater than 0.90 g / cm 3 ; the density of the metal-coated microbead modified foaming glue filling cavity after curing is not greater than 0.80 g / cm 3 ; the density of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate is not greater than 1.35 g / cm 3 .

[0057] Among them, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate is prepared by compounding raw materials with the following mass ratios: biomass fiber 41%, ultrafine barium sulfate prefabricated masterbatch 35%, plastic matrix 15%, interfacial compatibilizer 6%, lubricant 3%. The ultrafine barium sulfate prefabricated masterbatch is prepared by compounding raw materials with the following mass ratios: ultrafine barium sulfate of 800 mesh and above 45%, coupling agent 5.5%, lubricating dispersant 3.3%, surfactant 1.2%, plastic matrix 45%.

[0058] The metal-coated microbead modified foaming glue filling cavity is prepared from 75% of wet-curing polyurethane foaming glue and 25% of metal-coated microbeads with the following mass ratio.

[0059] The metal-coated microbead blended modified surface co-extrusion layer is prepared from 7% of metal-coated microbeads, 60% of plastic matrix, 12% of ionomer, and 21% of functional additives with the following mass ratio.

[0060] As Figure 13 shown, the preparation steps of the lightweight radiation-proof wood-plastic composite material are as follows: S1. Prepare wood-plastic pellets. Inject the raw materials of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate: biomass fiber, ultrafine barium sulfate prefabricated masterbatch, plastic matrix, interfacial compatibilizer and lubricant into a high-speed mixer according to the ratio, and carry out uniform mixing to obtain a mixture. Then, the mixture is introduced into a flat double granulator to make wood-plastic pellets; S2. Molding of the wood-plastic substrate. Introduce the wood-plastic pellets prepared in S1 into the main extruder for plasticization and melting, and then transport them to the wood-plastic substrate forming part of the customized mold to form an ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate; S3. Prepare co-extrusion pellets. The raw materials of the metal-coated microbead co-blended modified surface co-extrusion layer: plastic matrix, ionomer and functional filler are first made into co-extrusion pellets by a mixing and granulating integrated machine; S4. Molding of the surface co-extrusion layer. Introduce the co-extrusion pellets prepared in S3 into the high-shear kneading part of the co-extrusion device to complete plasticization, melting and blending to form a front melt. Subsequently, the metal-coated microbeads are injected into the low-shear mixing part of the co-extrusion device in a spiral side feeding form to be mixed with the front melt. After the metal-coated microbeads are uniformly dispersed in the melt, they enter the uniform feeding part of the co-extrusion device and are transported to the surface co-extrusion plastic forming part of the customized mold to form a metal-coated microbead co-blended modified surface co-extrusion layer; S5. Molding of the foaming adhesive-filled cavity. The raw materials of the metal-coated microbead modified foaming adhesive-filled cavity: metal-coated microbeads and moisture-curing polyurethane foaming adhesive are respectively introduced into the modified foaming adhesive forming part of the customized mold through two different high-temperature-resistant polytetrafluoroethylene tubes by two injection machines to form a metal-coated microbead modified foaming adhesive-filled cavity; S6. Composite molding of the wood-plastic composite semi-finished product. The ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microbead co-blended modified surface co-extrusion layer are first compounded in the detachable straight section mold of the customized mold, and then compounded with the metal-coated microbead modified foaming adhesive-filled cavity at the customized orifice mold of the customized mold to form a wood-plastic composite semi-finished product; S7. Post-processing molding of the wood-plastic composite material. The wood-plastic composite semi-finished product finally undergoes surface embossing, cooling and shaping, grinding and wire drawing, fixed-length cutting and stacking and standing to prepare a lightweight radiation-proof wood-plastic composite material.

[0061] In S5, the metal-coated microbeads enter the customized mold through the polytetrafluoroethylene tube with high-speed and high-humidity air as the carrier, and the moisture-curing polyurethane foaming adhesive enters the customized mold in a high-pressure injection form through the polytetrafluoroethylene tube. The metal-coated microbeads and the moisture-curing polyurethane foaming adhesive come into contact and are mixed evenly, and the moisture in the high-humidity air promotes the curing and shaping of the moisture-curing polyurethane foaming adhesive.

[0062] Example 2 The difference between Example 2 and Example 1 of the present invention lies in that the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate is prepared from raw materials with the following component ratios: biomass fiber 55%, ultrafine barium sulfate prefabricated masterbatch 20%, plastic matrix 15%, interfacial compatibilizer 6%, lubricant 3%.

[0063] Example 3 The difference between Example 3 and Example 1 of the present invention lies in that the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate is prepared from raw materials with the following component ratios: biomass fiber 40%, ultrafine barium sulfate prefabricated masterbatch 50%, plastic matrix 5%, interfacial compatibilizer 3%, lubricant 2%.

[0064] Example 4 The difference between Example 4 and Example 1 of the present invention lies in that the ultrafine barium sulfate prefabricated masterbatch is prepared from raw materials with the following component ratios: ultrafine barium sulfate of 800 mesh and above 30%, coupling agent 8%, lubricating and dispersing agent 5.0%, surfactant 2%, plastic matrix 55%.

[0065] Example 5 The difference between Example 5 and Example 1 of the present invention lies in that the ultrafine barium sulfate prefabricated masterbatch is prepared from raw materials with the following component ratios: ultrafine barium sulfate of 800 mesh and above 60%, coupling agent 3%, lubricating and dispersing agent 1.8%, surfactant 1.2%, plastic matrix 35%.

[0066] Example 6 The difference between Example 6 and Example 1 of the present invention lies in that the metal-coated bead modified foaming adhesive filled cavity is prepared from raw materials with the following component ratios: moisture-curing polyurethane foaming adhesive 60%, metal-coated beads 40%.

[0067] Example 7 The difference between Example 7 and Example 1 of the present invention lies in that the metal-coated bead modified foaming adhesive filled cavity is prepared from raw materials with the following component ratios: moisture-curing polyurethane foaming adhesive 85%, metal-coated beads 15%.

[0068] Example 8 The difference between Example 8 and Example 1 of the present invention lies in that the metal-coated bead blended and modified surface co-extrusion layer is prepared from raw materials with the following component ratios: metal-coated beads 4%, plastic matrix 63%, ionomer 12%, functional filler 21%.

[0069] Example 9 The difference between Example 9 and Example 1 of the present invention lies in that the metal-coated microbead blend-modified surface co-extruded layer is prepared from raw materials with the following component ratios: 10% metal-coated microbeads, 57% plastic matrix, 12% ionomer, and 21% functional filler.

[0070] Comparative Example 1 The difference between Comparative Example 1 and Example 1 lies in that the ultrafine barium sulfate preformed masterbatch-modified wood-plastic substrate is prepared from raw materials with the following component ratios: 80% biomass fiber, 0% ultrafine barium sulfate preformed masterbatch, 15% plastic matrix, 3% interfacial compatibilizer, and 2% lubricant.

[0071] Comparative Example 2 The difference between Comparative Example 2 and Example 1 lies in that the metal-coated microbead-modified foaming adhesive-filled cavity is prepared from raw materials with the following component ratios: 100% moisture-curing polyurethane foaming adhesive, 0 metal-coated microbeads.

[0072] Comparative Example 3 The difference between Comparative Example 3 and Example 1 lies in that the metal-coated microbead blend-modified surface co-extruded layer is prepared from raw materials with the following component ratios: 0 metal-coated microbeads, 67% plastic matrix, 12% ionomer, and 21% functional filler.

[0073] The composite materials prepared in the above Examples 1-9 and Comparative Examples 1-3 were subjected to material property tests, and the test data of the density and radiation protection lead equivalent of the materials are shown in Table 1.

[0074] Lead equivalent test: The radiation protection board is compared with a pure lead standard sheet. Under the condition of achieving the same X-ray transmittance, the thickness of the pure lead standard sheet is used as the lead equivalent.

[0075] Table 1 Performance test data of the composite materials prepared in Examples 1-9 and Comparative Examples 1-3

[0076] It can be seen from Table 1 that the radiation protection performance of the lightweight radiation protection composite material of the present invention is significantly enhanced, and the three structures work together synergistically, and this radiation protection effect can play a synergistic role within the mixing ratio range of the present invention.

[0077] Such as Figures 1 - 12As shown in the figure, in the technical solution of the present invention, a co-extrusion device for lightweight radiation-proof wood-plastic composite materials is provided, including a customized mold 1, a high-speed mixer 2, a twin-screw pelletizer 3, a first elevator 4, a main extruder 5, two injection machines 6, a co-extrusion device 8, a spiral side feeder 9, a second elevator 10 and a mixing and pelletizing integrated machine 11. The main extruder 5 and the co-extrusion device 8 are connected to the left and right sides of the customized mold 1. The high-speed mixer 2, the twin-screw pelletizer 3 and the first elevator 4 are connected in sequence through pipelines, and the first elevator 4 is connected to the main extruder 5 through a pipeline. The mixing and pelletizing integrated machine 11 is located at the rear side of the customized mold 1. The mixing and pelletizing integrated machine 11, the second elevator 10 and the co-extrusion device 8 are connected in sequence through pipelines. The spiral side feeder 9 is arranged above the co-extrusion device 8, and the spiral side feeder 9 is connected to the co-extrusion device 8 through a pipeline. The two injection machines 6 are located in front of the customized mold 1, and both the two injection machines 6 and the customized mold 1 are connected through polytetrafluoroethylene tubes.

[0078] Inject the raw materials for the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate: biomass fiber, ultrafine barium sulfate prefabricated masterbatch, plastic matrix, interfacial compatibilizer and lubricant into the high-speed mixer 2 according to the ratio for uniform mixing to obtain a mixed material. Then, the mixed material is introduced into the twin-screw pelletizer 3 to make wood-plastic pellets. The prepared wood-plastic pellets are introduced into the main extruder 5 through the first elevator 4 for plasticization and melting, and then transported to the customized mold 1 to form the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate. The raw materials for the metal-coated microbead co-mixed modified surface co-extrusion layer: plastic matrix, ionomer and functional filler are first made into co-extrusion pellets by the mixing and pelletizing integrated machine 11. It enters the co-extrusion device 8 through the second elevator 10 to complete plasticization, melting and co-mixing to form a front melt. Subsequently, the metal-coated microbeads are injected into the co-extrusion device 8 through the spiral side feeder 9 to be mixed with the front melt. After the metal-coated microbeads are evenly dispersed in the melt, it is transported to the customized mold 1 to form the metal-coated microbead co-mixed modified surface co-extrusion layer. The raw materials for the metal-coated microbead modified foaming glue filled cavity: metal-coated microbeads and moisture-curing polyurethane foaming glue are respectively introduced into the customized mold 1 through two injection machines 6 by two different high-temperature resistant polytetrafluoroethylene tubes to form the metal-coated microbead modified foaming glue filled cavity. The ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microbead co-mixed modified surface co-extrusion layer are first compounded in the customized mold 1, and then compounded with the metal-coated microbead modified foaming glue filled cavity in the customized mold 1 to form a semi-finished wood-plastic composite material. Finally, the semi-finished wood-plastic composite material undergoes surface embossing, cooling and shaping, grinding and wire drawing, fixed-length cutting and stacking and standing to prepare the lightweight radiation-proof wood-plastic composite material.

[0079] The customized mold 1 includes a dual-output speed reducer 14, a customized lower mold 21, a wood-plastic substrate forming part, a surface co-extruded plastic forming part 7, a modified foaming adhesive forming part 12, and a guiding forming assembly 16. Both ends of the dual-output speed reducer 14 are provided with compound motors 13 drivingly connected thereto. Inside the customized lower mold 21, two symmetrically arranged material extrusion rollers 18 are rotatably provided. The two output shafts of the dual-output speed reducer 14 are respectively drivingly connected to the material extrusion rollers 18 on the same side. The upper end of the customized lower mold 21 is detachably provided with a customized upper mold 17. Main feed port sections 22 are provided on both the left and right sides between the customized upper mold 17 and the customized lower mold 21. In the middle of the customized lower mold 21, a number of adjustable baffle plates 19 are provided. The adjustable baffle plates 19 extend into the inside of the customized lower mold 21. A detachable straight section mold 28 is slidably provided at the lower end of the customized lower mold 21. A handle 23 is provided on the front side of the detachable straight section mold 28. Two rows of left-right symmetrically arranged guide wheels 29 are provided at the lower end of the detachable straight section mold 28. A number of temperature sensors 24 are provided on the detachable straight section mold 28. A customized die orifice 20 is detachably provided at the lower end of the detachable straight section mold 28.

[0080] Place the dual-output speed reducer 14, the customized lower mold 21, and the compound motor 13 on the storage platform. According to the finished product requirements, adjust the height of a number of adjustable baffle plates 19, so as to adjust the thickness of the material output by the customized lower mold 21. A detachable straight section mold 28 is slidably provided at the lower end of the customized lower mold 21. The detachable straight section mold 28 of the corresponding size can be replaced as needed. The handle 23 is used to pull out and slide the detachable straight section mold 28 in and out of the lower end of the customized lower mold 21 for disassembly. The guide wheels 29 are used to abut against the storage platform to facilitate pulling out and placing the detachable straight section mold 28. The output shaft of the compound motor 13 drives the input shaft of the dual-output speed reducer 14 on the same side to rotate. Thus, the two output shafts of the dual-output speed reducer 14 respectively drive the material extrusion rollers 18 on the same side to rotate synchronously and reversely inside the customized lower mold 21. The ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microbead blended modified surface co-extruded layer respectively enter between the customized upper mold 17 and the customized lower mold 21 from the main feed port sections 22, and are conveyed downward by the material extrusion rollers 18 to the detachable straight section mold 28, so that the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microbead blended modified surface co-extruded layer are compounded. After compounding, they enter the customized die orifice 20. The metal-coated microbead modified foaming adhesive filling cavity enters the customized die orifice 20 for compounding to form a wood-plastic composite semi-finished product, and then enters the guiding forming assembly 16 for roll pressing and output.

[0081] The customized die orifice 20 includes a die orifice main body 26. The die orifice main body 26 is detachably provided at the lower end of the detachable straight section mold 28, and the die orifice main body 26 is communicated with the detachable straight section mold 28. A side feed port section 25 is provided on the right side of the die orifice main body 26. A composite outlet section 27 is provided at the lower part of the die orifice main body 26.

[0082] The prefabricated masterbatch of ultrafine barium sulfate modified wood-plastic substrate and the composite of the metal-coated microbead modified surface co-extrusion layer enter the main body 26 of the die through compounding. The metal-coated microbead modified foaming adhesive filling cavity enters the main body 26 of the die from the side feeding port section 25 and is compounded with the composite of the prefabricated masterbatch of ultrafine barium sulfate modified wood-plastic substrate and the metal-coated microbead modified surface co-extrusion layer to form a semi-finished wood-plastic composite material, which is output downward from the composite outlet section 27.

[0083] The wood-plastic substrate forming part is connected to the discharging end of the main extruder 5. The wood-plastic substrate forming part is connected and abutted against the main feeding port section 22 on the left side. The surface co-extruded plastic forming part 7 is connected and abutted against the main feeding port section 22 on the right side. The modified foaming adhesive forming part 12 and the guiding forming assembly 16 are both arranged above the surface co-extruded plastic forming part 7. The modified foaming adhesive forming part 12 is connected and abutted against the side feeding port section 25. The wood-plastic substrate forming part has the same structure as the surface co-extruded plastic forming part 7, and the wood-plastic substrate forming part, the surface co-extruded plastic forming part 7 and the modified foaming adhesive forming part 12 are all T-shaped extrusion dies. The main extruder 5 transports the raw material of the prefabricated masterbatch of ultrafine barium sulfate modified wood-plastic substrate to the wood-plastic substrate forming part. After forming, it is injected into the main feeding port section 22 on the left side. The raw material of the metal-coated microbead modified surface co-extrusion layer is injected into the surface co-extruded plastic forming part 7. After forming, it is injected into the main feeding port section 22 on the right side. The raw material of the metal-coated microbead modified foaming adhesive filling cavity is injected into the modified foaming adhesive forming part 12. After forming, it is injected into the side feeding port section 25. The T-shaped extrusion die is used for injection molding.

[0084] The guiding forming assembly 16 is located below the customized die 20. The guiding forming assembly 16 includes a guiding frame 32. A first roller 30, a second roller 31 and a third roller 33 are sequentially rotatably arranged on the guiding frame 32 from left to right. A guiding motor 34 is fixed on the side part of the guiding frame 32. The output shaft of the guiding motor 34 is fixedly connected to the rotating shaft of the second roller 31. The composite outlet section 27 is located between the first roller 30 and the second roller 31.

[0085] After the metal-coated microbead modified foaming adhesive filling cavity is compounded with the composite of the prefabricated masterbatch of ultrafine barium sulfate modified wood-plastic substrate and the metal-coated microbead modified surface co-extrusion layer, a semi-finished wood-plastic composite material is formed. The semi-finished wood-plastic composite material is output downward from the composite outlet section 27, first enters between the first roller 30 and the second roller 31, and then enters between the second roller 31 and the third roller 33. The output shaft of the guiding motor 34 drives the rotating shaft of the second roller 31 to rotate, and stably roller presses and transports the semi-finished wood-plastic composite material.

[0086] The mixing and granulating integrated machine 11 includes a granulator main body 42. Above the granulator main body 42, a discharge valve one 40 and a discharge motor one 41 are fixed. The output shafts of the discharge valve one 40 and the discharge motor one 41 are in transmission connection. At the upper end of the discharge valve one 40, a mixing tank one 37 is fixed. At the upper end of the mixing tank one 37, a mixing motor one 36 and a feed hopper one 35 communicated therewith are fixed. Inside the mixing tank one 37, a material stirring rod 38 is rotatably provided. The material stirring rod 38 is in transmission connection with the output shaft of the mixing motor one 36. At the lower end of the material stirring rod 38, a spiral discharge rod 39 is fixed. The raw materials of the metal-coated microbead co-blended modified surface co-extrusion layer: plastic matrix, ionic polymer and functional filler are injected into the mixing tank one 37 through the feed hopper one 35. The output shaft of the mixing motor one 36 drives the material stirring rod 38 to rotate inside the mixing tank one 37. The material stirring rod 38 drives the spiral discharge rod 39 to rotate. The material stirring rod 38 stably mixes the raw materials. After mixing, the spiral discharge rod 39 injects the mixed raw materials into the discharge valve one 40, completing discharging while mixing. The output shaft of the discharge motor one 41 drives the discharge valve one 40 to work, injecting the mixed raw materials into the granulator main body 42 for granulation, obtaining the co-extrusion granulation material, and then entering the co-extrusion device 8 through the second elevator 10.

[0087] The co-extrusion device 8 includes a plurality of support frames 44. On the plurality of support frames 44, a co-extrusion twin-screw assembly 46 is provided. On the rightmost support frame 44, a synchronous reverse double-output member 50 and a granulation motor 51 are fixed. The output shaft of the granulation motor 51 is in transmission connection with the input shaft of the synchronous reverse double-output member 50. The two output shafts of the synchronous reverse double-output member 50 are in transmission connection with the co-extrusion twin-screw assembly 46. On the co-extrusion twin-screw assembly 46, a discharge valve two 48 and a discharge motor two 49 are fixed. The output shafts of the discharge valve two 48 and the discharge motor two 49 are in transmission connection. At the upper end of the discharge valve two 48, a feed hopper two 47 communicated therewith is provided. At the discharge end of the co-extrusion twin-screw assembly 46, a discharge die 43 is provided. The discharge die 43 is in contact connection with the surface co-extrusion plastic forming part 7. Outside the co-extrusion twin-screw assembly 46, a plurality of temperature controllers 45 are provided. The co-extrusion granulation material of the metal-coated microbead co-blended modified surface co-extrusion layer is injected into the feed hopper two 47 through the second elevator 10. The output shaft of the discharge motor two 49 drives the discharge valve two 48 to work, injecting the co-extrusion granulation material into the co-extrusion twin-screw assembly 46. The two output shafts of the synchronous reverse double-output member 50 drive the co-extrusion twin-screw assembly 46 to work, performing plasticization, melting and co-blending. The plurality of temperature controllers 45 control the temperature to ensure the quality of plasticization, melting and co-blending, forming a front melt. Subsequently, the metal-coated microbeads are injected into the co-extrusion device 8 through the spiral side feeder 9 and mixed with the front melt. After the metal-coated microbeads are uniformly dispersed in the melt, they are transmitted from the discharge die 43 to the surface co-extrusion plastic forming part 7.

[0088] The co-extrusion twin-screw assembly 46 includes two co-extrusion pipes 52 that can be disassembled and assembled vertically. Between the two co-extrusion pipes 52, two co-extrusion screws 59 are rotatably provided. The co-extrusion screws 59 are drivingly connected to the two output shafts of the synchronous reverse double-output member 50. From right to left, the co-extrusion screws 59 are successively provided with a feeding thread 58, a high-shear thread I 57, a high-shear thread II 56, a high-shear thread III 55, a low-shear thread 54, and a uniform feeding thread 53. The co-extrusion twin-screw assembly 46 is successively provided with a feeding area, a high-shear mixing section 60, a low-shear mixing section 61, and a uniform feeding section 62 from right to left. The discharge valve II 48 and the feeding thread 58 are located in the feeding area. The high-shear thread I 57, the high-shear thread II 56, and the high-shear thread III 55 are located in the high-shear mixing section 60. The low-shear thread 54 is located in the low-shear mixing section 61. The uniform feeding thread 53 is located in the uniform feeding section 62. Feeding rollers are rotatably provided on the support frame 44, the surface co-extrusion plastic forming section 7, and the modified foaming adhesive forming section 12.

[0089] The two output shafts of the synchronous reverse double-output member 50 drive the two co-extrusion screws 59 to rotate synchronously in opposite directions. The co-extrusion granulation material of the metal-coated microbead co-blended modified surface co-extrusion layer enters the interiors of the two co-extrusion pipes 52, and successively passes through the feeding area, the high-shear mixing section 60, the low-shear mixing section 61, and the uniform feeding section 62. That is, the feeding thread 58 stably conveys it, and the high-shear thread I 57, the high-shear thread II 56, and the high-shear thread III 55 perform stable high-shear mixing to achieve the rapid melting and uniform mixing of the plastic matrix, ionomer, and functional filler. The low-shear thread 54 realizes the uniform dispersion of the metal-coated microbeads in the front melt and ensures that the spherical hollow microbeads are not crushed by extrusion. The uniform feeding thread 53 realizes the uniform and quantitative transmission of the composite melt of the plastic matrix, ionomer, functional filler, and metal-coated microbeads.

[0090] The spiral side feeder 9 includes a mounting plate 69. The mounting plate 69 is fixed to the upper ends of several support frames 44. A three-output shaft box 73 is fixed on the mounting plate 69. A feeding motor 63 is fixed on the three-output shaft box 73. The output shaft of the feeding motor 63 is drivingly connected to the input shaft of the three-output shaft box 73. A feeding pipe 71 is fixed on the three-output shaft box 73. The discharging end of the feeding pipe 71 is provided with a discharging pipe 70. The discharging pipe 70 is connected above the co-extrusion pipe 52 of the low-shear mixing section 61. Two feeding screws 72 are rotatably provided inside the feeding pipe 71. The feeding screws 72 are drivingly connected to the two synchronously reverse output shafts on the lower side of the three-output shaft box 73. The upper end of the feeding pipe 71 is provided with a mixing tank II 65 connected thereto. Another output shaft of the three-output shaft box 73 extends into the interior of the mixing tank II 65, and a mixing rod II 68 is fixed on another output shaft of the three-output shaft box 73. A mixing motor II 64 is fixed on the mixing tank II 65. A mixing rod I 67 is rotatably provided inside the mixing tank II 65. The output shaft of the mixing motor II 64 is drivingly connected to the mixing rod I 67. The upper end of the mixing tank II 65 is provided with a feeding pipe 66.

[0091] The metal-coated microbeads are injected into the interior of the second mixing tank 65 through the feed pipe 66. The output shaft of the second mixing motor 64 drives the first mixing rod 67 to rotate inside the second mixing tank 65 to stably feed the metal-coated microbeads. The output shaft of the feeding motor 63 drives the input shaft of the triple output shaft box 73 to rotate. Another output shaft of the triple output shaft box 73 drives the second mixing rod 68 to rotate for stable feeding. The two synchronously reverse output shafts on the lower side of the triple output shaft box 73 drive the feeding screw 72 to rotate synchronously and reversely inside the feed pipe 71, and uniformly and quantitatively introduce the metal-coated microbeads into the interior of the discharge pipe 70, so as to be injected into the co-extrusion pipe 52 of the low-shear mixing part 61 and mixed with the front melt. After the metal-coated microbeads are evenly dispersed in the melt, they are transferred from the discharge die 43 to the surface co-extrusion plastic forming part 7.

[0092] The injection machine 6 includes an injection vehicle body 75. Above the rear side of the injection vehicle body 75, there is a vehicle handle 74. A feeding pump 76 is fixed on the injection vehicle body 75. An inclined extrusion pipe 78 is also fixed on the injection vehicle body 75. At the lower discharge end of the extrusion pipe 78, there is a discharge joint 77. The upper end of the extrusion pipe 78 is fixed with a feeding hopper 79. A injection motor 80 is fixed on the feeding hopper 79. A sealing extrusion roller is fixed on the output shaft of the injection motor 80. The sealing extrusion roller is rotatably arranged inside the extrusion pipe 78. The output end of the feeding pump 76 is connected to the extrusion pipe 78 through a pipeline. The discharge joints 77 of the two injection machines 6 are both connected to the feed end of the modified foamed rubber forming part 12 through polytetrafluoroethylene pipes.

[0093] The raw materials for filling the cavity of the metal-coated microbead modified foamed rubber: metal-coated microbeads and moisture-curing polyurethane foamed rubber are respectively added to the two injection machines 6, or poured into the feeding hopper 79 or injected into the interior of the extrusion pipe 78 through the feeding pump 76. The output shaft of the injection motor 80 drives the sealing extrusion roller to rotate inside the extrusion pipe 78, and the material is led out from the discharge joint 77. The metal-coated microbeads enter the modified foamed rubber forming part 12 through the polytetrafluoroethylene pipe with high-speed and high-humidity air as the carrier. The moisture-curing polyurethane foamed rubber enters the modified foamed rubber forming part 12 in the form of high-pressure injection through the polytetrafluoroethylene pipe. The metal-coated microbeads and the moisture-curing polyurethane foamed rubber contact and mix evenly at the die orifice of the modified foamed rubber forming part 12, and the moisture in the high-humidity air promotes the curing and shaping of the moisture-curing polyurethane foamed rubber.

[0094] The working principle of the present invention: S1. Prepare the wood-plastic granule. The raw materials for modifying the wood-plastic base material with the ultrafine barium sulfate prefabricated masterbatch: biomass fiber, ultrafine barium sulfate prefabricated masterbatch, plastic matrix, interfacial compatibilizer and lubricant are injected into the high-speed mixer 2 according to the ratio for uniform mixing to obtain a mixture, and the mixture is then introduced into the flat double granulator 3 to make the wood-plastic granule; S2. Molding of the wood-plastic base material: The prepared wood-plastic pellets are introduced into the main extruder 5 through the first elevator 4 for plasticization and melting. The main extruder 5 transports the raw material of the wood-plastic base material modified by the ultrafine barium sulfate prefabricated masterbatch to the wood-plastic base material molding section. After forming the wood-plastic base material modified by the ultrafine barium sulfate prefabricated masterbatch, it is injected into the main feed port section 22 on the left side. S3. Preparation of the co-extrusion granulation material: The raw materials for the metal-coated microbead co-blended modified surface co-extrusion layer, namely the plastic matrix, ionomer, and functional filler, are injected into the first mixing tank 37 through the first feed hopper 35. The output shaft of the first mixing motor 36 drives the stirring rod 38 to rotate inside the first mixing tank 37. The stirring rod 38 drives the spiral discharge rod 39 to rotate. The stirring rod 38 stably mixes the raw materials. After mixing, the spiral discharge rod 39 injects the mixed raw materials into the first discharge valve 40 to complete discharging while mixing. The output shaft of the first discharge motor 41 drives the first discharge valve 40 to work, injecting the mixed raw materials into the granulator main body 42 for granulation to obtain the co-extrusion granulation material. S4. Molding of the surface co-extrusion layer: The co-extrusion granulation material of the metal-coated microbead co-blended modified surface co-extrusion layer is injected into the second feed hopper 47 through the second elevator 10. The output shaft of the second discharge motor 49 drives the second discharge valve 48 to work, injecting the co-extrusion granulation material into the co-extrusion twin-screw assembly 46. The two output shafts of the synchronous reverse double-output member 50 drive the two co-extrusion screws 59 to rotate synchronously in the reverse direction. The co-extrusion granulation material of the metal-coated microbead co-blended modified surface co-extrusion layer enters the two co-extrusion pipes 52, successively passing through the injection area, high-shear kneading section 60, low-shear mixing section 61, and uniform feeding section 62. A number of temperature controllers 45 control the temperature, and the guiding thread 58 stably transports it. The high-shear thread one 57, high-shear thread two 56, and high-shear thread three 55 perform stable high-shear kneading to achieve rapid melting and uniform mixing of the plastic matrix, ionomer, and functional filler, forming the front melt. The metal-coated microbeads are injected into the second mixing tank 65 through the feed pipe 66. The output shaft of the second mixing motor 64 drives the first mixing rod 67 to rotate inside the second mixing tank 65 to stably stir the metal-coated microbeads. The output shaft of the feeding motor 63 drives the input shaft of the three-output shaft box 73 to rotate. Another output shaft of the three-output shaft box 73 drives the second mixing rod 68 to rotate for stable stirring. The two synchronous reverse output shafts on the lower side of the three-output shaft box 73 drive the feeding screw 72 to rotate synchronously in the reverse direction inside the feeding pipe 71, uniformly and quantitatively guiding the metal-coated microbeads into the discharge pipe 70, and then injecting them into the co-extrusion pipe 52 of the low-shear mixing section 61. The low-shear thread 54 realizes the uniform dispersion of the metal-coated microbeads in the front melt and ensures that the spherical hollow microbeads are not crushed by extrusion. The uniform feeding thread 53 realizes the uniform and quantitative transmission of the composite melt of the plastic matrix, ionomer, functional filler, and metal-coated microbeads, and is transmitted from the discharge die 43 to the surface co-extrusion plastic molding section 7 to form the metal-coated microbead co-blended modified surface co-extrusion layer, which is injected into the main feed port section 22 on the right side. S5. Foaming adhesive fills the cavity to form. The raw materials for filling the cavity with metal-coated bead modified foaming adhesive: metal-coated beads and moisture-curing polyurethane foaming adhesive are respectively added to two injection machines 6, or poured into the feeding hopper 79 or injected into the inside of the extrusion pipe 78 through the feeding pump 76. The output shaft of the injection motor 80 drives the sealed extrusion roller to rotate inside the extrusion pipe 78, and the material is discharged through the material discharge joint 77. The metal-coated beads enter the modified foaming adhesive forming part 12 through a polytetrafluoroethylene tube with high-speed and high-humidity air as the carrier. The moisture-curing polyurethane foaming adhesive enters the modified foaming adhesive forming part 12 in the form of high-pressure injection through a polytetrafluoroethylene tube. The metal-coated beads and the moisture-curing polyurethane foaming adhesive contact and mix evenly at the die of the modified foaming adhesive forming part 12. The moisture in the high-humidity air promotes the curing and shaping of the polyurethane foaming adhesive, forming a metal-coated bead modified foaming adhesive filled cavity; S6. Composite forming of the wood-plastic composite semi-finished product. The ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated bead co-blended modified surface co-extrusion layer respectively enter the inside of the customized upper die 17 and the customized lower die 21 from the main feeding port sections 22 on the left and right sides, and are conveyed downward by the extrusion roller 18 to the detachable straight section die 28, so that the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated bead co-blended modified surface co-extrusion layer are compounded. After compounding, they enter the die body 26. The metal-coated bead modified foaming adhesive filled cavity enters the die body 26 from the side feeding port section 25 and is compounded with the composite body of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated bead co-blended modified surface co-extrusion layer to form a wood-plastic composite semi-finished product, and then is output downward from the composite outlet section 27. First, it enters between the first roller 30 and the second roller 31, and then enters between the second roller 31 and the third roller 33. The output shaft of the guiding motor 34 drives the rotating shaft of the second roller 31 to rotate, stably roller-pressing and conveying the wood-plastic composite semi-finished product. The wood-plastic composite semi-finished product is sequentially output from the rotating feeding rollers on the right support frame 44, the surface co-extrusion plastic forming part 7 and the modified foaming adhesive forming part 12; S7. Post-processing forming of the wood-plastic composite. The wood-plastic composite semi-finished product finally undergoes surface embossing, cooling and shaping, grinding and wire drawing, fixed-length cutting and stacking and standing to prepare a lightweight radiation-proof wood-plastic composite.

[0095] In summary, by the cooperation of the high-speed mixer 2, the twin-screw pelletizer 3, the first elevator 4 and the main extruder 5, and then in cooperation with the wood-plastic base material forming section, the rapid and efficient preparation of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic base material is realized; by the cooperation of the mixing and pelletizing integrated machine 11, the second elevator 10 and the co-extrusion device 8, and the cooperation of the co-extrusion device 8 and the screw side feeder 9, and then in cooperation with the surface co-extruded plastic forming section 7, the rapid and efficient preparation of the metal-coated bead blended modified surface co-extruded layer is realized; by the cooperation of the two injection machines 6 and the modified foaming adhesive forming section 12, the rapid and efficient preparation of the metal-coated bead modified foaming adhesive filled cavity is realized; by the customized mold 1, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic base material and the metal-coated bead blended modified surface co-extruded layer are quickly compounded, and then the metal-coated bead modified foaming adhesive filled cavity and the composite of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic base material and the metal-coated bead blended modified surface co-extruded layer are compounded, so as to realize the stable and efficient preparation of the semi-finished wood-plastic composite material; by the cooperation of the guiding forming assembly 16 and the customized die 20, the stable roll pressing output is achieved, and then in cooperation with the modified foaming adhesive forming section 12, the surface co-extruded plastic forming section 7 and the support frame 44, the stable output is achieved.

[0096] The lightweight radiation-proof wood-plastic composite material of the present invention can meet the requirements of the medical radiation-proof building material standard. The metal-coated bead blended modified surface co-extruded layer and the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic base material cooperate with each other for radiation protection, have a small density, are lightweight, and have a good interfacial compatibility effect.

[0097] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A lightweight radiation-proof wood-plastic composite material, characterized in that, It is composed of a surface co-extruded layer modified by blending metal-coated microbeads, a wood-plastic substrate modified by an ultrafine barium sulfate prefabricated masterbatch, and a cavity filled with a metal-coated microbead modified foaming adhesive, which are distributed in sequence from the outside to the inside. Multiple groups of cavities filled with the metal-coated microbead modified foaming adhesive are arranged in parallel in the wood-plastic substrate modified by the ultrafine barium sulfate prefabricated masterbatch; The material density of the metal-plated microbead blend-modified surface co-extruded layer is not greater than 0.90 g / cm 3 ; The density of the metal-plated microbead modified foaming glue filled cavity after curing is not greater than 0.80 g / cm 3 ; The density of the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate is not greater than 1.35 g / cm 3 ; The metal-coated microbead blended and modified surface co-extrusion layer, the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate, and the metal-coated microbead modified foaming adhesive filled cavity cooperate to prevent radiation; the density of the lightweight radiation-proof wood-plastic composite material is not greater than 1.20 g / cm 3 , and the lead equivalent for X-rays is 1.0 - 1.7 mmPb / c.

2. The lightweight radiation-proof wood-plastic composite material according to claim 1, wherein The wood-plastic substrate modified by the ultrafine barium sulfate prefabricated masterbatch is prepared by compounding raw materials with the following mass ratios: biomass fiber 40% - 65%, ultrafine barium sulfate prefabricated masterbatch 20% - 50%, plastic matrix 5% - 25%, interfacial compatibilizer 2% - 10%, lubricant 0.5% - 5%; The ultrafine barium sulfate prefabricated masterbatch is prepared by compounding raw materials with the following mass ratios: ultrafine barium sulfate of 800 mesh and above 30% - 60%, coupling agent 3% - 8%, lubricating and dispersing agent 1.5% - 5.0%, surfactant 0.5% - 2%, plastic matrix 35% - 55%; The cavity filled with the metal-coated microbead modified foaming adhesive is prepared from raw materials with the following mass ratios: moisture-curing polyurethane foaming adhesive 60% - 85%, metal-coated microbeads 15% - 40%; The surface co-extruded layer modified by blending metal-coated microbeads is prepared by compounding raw materials with the following mass ratios: metal-coated microbeads 4% - 10%, plastic matrix 40% - 80%, ionomer 4% - 20%, functional additive 5% - 30%.

3. The lightweight radiation-proof wood-plastic composite material according to claim 2, characterized in that, The plastic matrix in the ultrafine barium sulfate prefabricated masterbatch, the wood-plastic substrate modified by the ultrafine barium sulfate prefabricated masterbatch, and the surface co-extruded layer modified by blending metal-coated microbeads is at least one of polyethylene, polypropylene, polyvinyl chloride, and polystyrene; The metal-coated microbeads in the metal-coated microbead modified foaming adhesive filled cavity and the co-extruded surface layer modified by blending the metal-coated microbeads are made with fly ash hollow as the matrix, and at least one of lead, copper, aluminum, iron or tungsten metal is deposited and coated on the surface of the microbeads through magnetron sputtering technology. The particle size of the metal-coated microbeads is 0.5 - 30 μm, the thickness of the metal coating of the metal-coated microbeads is not less than 0.1 μm, and the bulk density is not more than 0.85 g / cm 3 .

4. The lightweight radiation-proof wood-plastic composite material according to claim 3, characterized in that, The coupling agent in the ultrafine barium sulfate prefabricated masterbatch is at least one of silane, titanate, and aluminate coupling agents; the lubricating and dispersing agent is at least one of zinc stearate, calcium stearate, distilled monoglyceride stearate, pentaerythritol stearate, hyperbranched polyester, and hyperbranched polyamide; the surfactant is at least one of oleic acid, lauric acid, white oil, and mineral oil.

5. The lightweight radiation-proof wood-plastic composite material according to claim 4, characterized in that, The biomass fiber in the wood-plastic substrate modified by the ultrafine barium sulfate prefabricated masterbatch is at least one of wood, bamboo, cotton, hemp, rice husk, wheat straw, soybean skin, oil-tea fruit shell, coffee residue, peanut shell, and coconut shell fiber; the interfacial compatibilizer is at least one of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, glycidyl methacrylate grafted polyethylene, titanate, aluminate, and silane coupling agents; the lubricant is at least one of PE wax, stearic acid, calcium stearate, zinc stearate, oxidized polyethylene, and ethylene bis-stearamide. The ionomer in the surface co-extruded layer modified by blending metal-coated microbeads is at least one of sodium ion polymers, zinc ion polymers, and lithium-sodium ion polymers; the functional additive is at least one of toughening modification, wear resistance modification, anti-slip modification, anti-aging modification, and flame retardant modification additives; the functional additive imparts any one of high impact toughness, ultraviolet reflection, infrared reflection, anti-slip, flame retardant, wear resistance, and scratch resistance to the surface co-extruded layer.

6. A preparation method of the lightweight radiation-proof wood-plastic composite material according to any one of claims 1-5, characterized in that, The specific preparation steps are as follows: S1. Prepare the wood-plastic granulate. Inject the raw materials for the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate, namely biomass fiber, ultrafine barium sulfate prefabricated masterbatch, plastic matrix, interfacial compatibilizer and lubricant, into a high-speed mixer according to the ratio, and uniformly mix them to obtain a mixed material. Then, introduce the mixed material into a flat double granulator to make the wood-plastic granulate; S2. Form the wood-plastic substrate. Introduce the wood-plastic granulate prepared in S1 into the main extruder for plasticization and melting, and then transport it to the wood-plastic substrate forming part of a customized mold to form the ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate; S3. Prepare the co-extrusion granulate. First, use a mixing and granulating integrated machine to make the co-extrusion granulate from the raw materials for the metal-coated microbead co-blended modified surface co-extrusion layer, namely plastic matrix, ionomer and functional filler; S4. Form the surface co-extrusion layer. Introduce the co-extrusion granulate prepared in S3 into the high-shear kneading part of the co-extrusion device to complete plasticization, melting and blending to form a front melt. Subsequently, inject the metal-coated microbeads into the low-shear mixing part of the co-extrusion device in the form of screw side feeding to mix with the front melt. After the metal-coated microbeads are evenly dispersed in the melt, enter the uniform feeding part of the co-extrusion device and be transported to the surface co-extrusion plastic forming part of the customized mold to form the metal-coated microbead co-blended modified surface co-extrusion layer; S5. Form the cavity filled with foaming adhesive. The raw materials for the cavity filled with the metal-coated microbead modified foaming adhesive, namely metal-coated microbeads and moisture-curing polyurethane foaming adhesive, are respectively introduced into the modified foaming adhesive forming part of the customized mold through two different high-temperature resistant polytetrafluoroethylene tubes by two injection machines to form the cavity filled with the metal-coated microbead modified foaming adhesive; S6. Composite form the semi-finished wood-plastic composite. The ultrafine barium sulfate prefabricated masterbatch modified wood-plastic substrate and the metal-coated microbead co-blended modified surface co-extrusion layer are first compounded in the detachable straight section mold of the customized mold, and then compounded with the cavity filled with the metal-coated microbead modified foaming adhesive at the customized die orifice of the customized mold to form a semi-finished wood-plastic composite; S7. Post-process and form the wood-plastic composite. The semi-finished wood-plastic composite finally undergoes surface embossing, cooling and shaping, grinding and wire drawing, fixed-length cutting and stacking and standing to prepare the lightweight radiation-proof wood-plastic composite.

7. The preparation method of the lightweight radiation-proof wood-plastic composite material according to claim 6, characterized in that, In step S5, the metal-coated microbeads enter the customized mold through a polytetrafluoroethylene tube with high-speed and high-humidity air as the carrier, and the moisture-curing polyurethane foaming adhesive enters the customized mold in the form of high-pressure injection through a polytetrafluoroethylene tube. The metal-coated microbeads and the moisture-curing polyurethane foaming adhesive come into contact and are evenly mixed, and the moisture in the high-humidity air promotes the curing and shaping of the moisture-curing polyurethane foaming adhesive.

8. A co-extrusion device for preparing the lightweight radiation-proof wood-plastic composite material according to any one of claims 1-5, characterized in that, It includes a customized mold (1), a high-speed mixer (2), a twin-screw pelletizer (3), a first elevator (4), a main extruder (5), two injection feeders (6), a co-extrusion device (8), a spiral side feeder (9), a second elevator (10) and a mixing and pelletizing integrated machine (11). The main extruder (5) and the co-extrusion device (8) are connected to the left and right sides of the customized mold (1). The high-speed mixer (2), the twin-screw pelletizer (3) and the first elevator (4) are connected in sequence by pipelines, and there is a pipeline connection between the first elevator (4) and the main extruder (5). The mixing and pelletizing integrated machine (11) is located at the rear side of the customized mold (1). The mixing and pelletizing integrated machine (11), the second elevator (10) and the co-extrusion device (8) are connected in sequence by pipelines. The spiral side feeder (9) is arranged above the co-extrusion device (8), and there is a pipeline connection between the spiral side feeder (9) and the co-extrusion device (8). The two injection feeders (6) are located at the front side of the customized mold (1), and both of the two injection feeders (6) are connected to the customized mold (1) by polytetrafluoroethylene pipes.

9. The co-extrusion device for a lightweight radiation-proof wood-plastic composite material according to claim 8, characterized in that, The customized mold (1) includes a double-output speed reducer (14), a customized lower mold (21), a wood-plastic base material forming part, a surface co-extruded plastic forming part (7), a modified foaming glue forming part (12) and a guiding forming component (16). Composite motors (13) are arranged at both ends of the double-output speed reducer (14) and are in transmission connection with it. Two symmetrically arranged extrusion rollers (18) are rotatably arranged inside the customized lower mold (21). The two output shafts of the double-output speed reducer (14) are respectively in transmission connection with the extrusion rollers (18) on the same side. The customized upper mold (17) is detachably arranged at the upper end of the customized lower mold (21). Main feed port sections (22) are arranged on the left and right sides between the customized upper mold (17) and the customized lower mold (21). A number of adjusting baffle plates (19) are arranged in the middle of the customized lower mold (21), and the adjusting baffle plates (19) extend into the inside of the customized lower mold (21). A detachable straight section mold (28) is slidably arranged at the lower end of the customized lower mold (21). A handle (23) is arranged on the front side of the detachable straight section mold (28). Two rows of left-right symmetrically arranged guide wheels (29) are arranged at the lower end of the detachable straight section mold (28). A number of temperature sensors (24) are arranged on the detachable straight section mold (28). A customized die (20) is detachably arranged at the lower end of the detachable straight section mold (28); The customized die (20) includes a die body (26). The die body (26) is detachably arranged at the lower end of the detachable straight section mold (28), and the die body (26) is communicated with the detachable straight section mold (28). A side feed port section (25) is arranged on the right side part of the die body (26). A composite outlet section (27) is arranged at the lower part of the die body (26); The wood-plastic base material forming part is connected to the discharge end of the main extruder (5). The wood-plastic base material forming part is connected and abutted against the main feed port section (22) on the left side. The surface co-extruded plastic forming part (7) is connected and abutted against the main feed port section (22) on the right side. The modified foaming adhesive forming part (12) and the guiding forming component (16) are both arranged above the surface co-extruded plastic forming part (7). The modified foaming adhesive forming part (12) is connected and abutted against the side feed port section (25). The wood-plastic base material forming part has the same structure as the surface co-extruded plastic forming part (7), and the wood-plastic base material forming part, the surface co-extruded plastic forming part (7) and the modified foaming adhesive forming part (12) are all T-shaped extrusion dies; The guiding forming component (16) is located below the customized die (20). The guiding forming component (16) includes a guiding frame (32). A first roller (30), a second roller (31) and a third roller (33) are sequentially rotatably arranged on the guiding frame (32) from left to right. A guiding motor (34) is fixed to the side of the guiding frame (32). The output shaft of the guiding motor (34) is fixedly connected to the rotating shaft of the second roller (31). The composite outlet section (27) is located between the first roller (30) and the second roller (31).

10. The co-extrusion device of a lightweight radiation-proof wood-plastic composite material according to claim 9, characterized in that, The mixing and granulating integrated machine (11) includes a granulating machine main body (42). A discharge valve one (40) and a discharge motor one (41) are fixed above the granulating machine main body (42). The output shafts of the discharge valve one (40) and the discharge motor one (41) are in transmission connection. The upper end of the discharge valve one (40) is fixed with a mixing tank one (37). The upper end of the mixing tank one (37) is fixed with a mixing motor one (36) and a feed hopper one (35) communicated therewith. A material stirring rod (38) is rotatably arranged inside the mixing tank one (37). The material stirring rod (38) is in transmission connection with the output shaft of the mixing motor one (36). The lower end of the material stirring rod (38) is fixed with a spiral discharge rod (39); The co-extrusion device (8) includes a plurality of support frames (44). A co-extrusion twin-screw assembly (46) is arranged on the plurality of support frames (44). A synchronous reverse double-output part (50) and a granulating motor (51) are fixed on the rightmost support frame (44). The output shaft of the granulating motor (51) is in transmission connection with the input shaft of the synchronous reverse double-output part (50). The two output shafts of the synchronous reverse double-output part (50) are in transmission connection with the co-extrusion twin-screw assembly (46). A discharge valve two (48) and a discharge motor two (49) are fixed on the co-extrusion twin-screw assembly (46). The output shafts of the discharge valve two (48) and the discharge motor two (49) are in transmission connection. The upper end of the discharge valve two (48) is provided with a feed hopper two (47) communicated therewith. The discharge end of the co-extrusion twin-screw assembly (46) is provided with a discharge die (43). The discharge die (43) is in contact connection with the surface co-extruded plastic forming part (7). A plurality of temperature controllers (45) are arranged outside the co-extrusion twin-screw assembly (46); The co-extrusion twin-screw assembly (46) includes two co-extrusion pipes (52) that can be disassembled and assembled vertically. Between the two co-extrusion pipes (52), two co-extrusion screws (59) are rotatably arranged. The co-extrusion screws (59) are drivingly connected to the two output shafts of the synchronous reverse double-output member (50). The co-extrusion screws (59) are successively provided with a feeding thread (58), a high-shear thread one (57), a high-shear thread two (56), a high-shear thread three (55), a low-shear thread (54), and a uniform feeding thread (53) from right to left. The co-extrusion twin-screw assembly (46) is successively provided with a feeding area, a high-shear kneading section (60), a low-shear mixing section (61), and a uniform feeding section (62) from right to left. The discharging valve two (48) and the feeding thread (58) are located in the feeding area. The high-shear thread one (57), the high-shear thread two (56), and the high-shear thread three (55) are located in the high-shear kneading section (60). The low-shear thread (54) is located in the low-shear mixing section (61). The uniform feeding thread (53) is located in the uniform feeding section (62). On the support frame (44), the surface co-extrusion plastic molding section (7), and the modified foaming glue molding section (12), there are rotatably arranged feeding rollers. The spiral side feeder (9) includes a mounting plate (69). The mounting plate (69) is fixed to the upper ends of several support frames (44). A three-output shaft box (73) is fixed on the mounting plate (69). A feeding motor (63) is fixed on the three-output shaft box (73). The output shaft of the feeding motor (63) is drivingly connected to the input shaft of the three-output shaft box (73). A feeding pipe (71) is fixed on the three-output shaft box (73). The discharging end of the feeding pipe (71) is provided with a discharging pipe (70). The discharging pipe (70) is connected above the co-extrusion pipe (52) of the low-shear mixing section (61). Inside the feeding pipe (71), two feeding screws (72) are rotatably arranged. The feeding screws (72) are drivingly connected to the two synchronously reverse output shafts on the lower side of the three-output shaft box (73). The upper end of the feeding pipe (71) is provided with a mixing tank two (65) connected thereto. Another output shaft of the three-output shaft box (73) extends into the interior of the mixing tank two (65), and a mixing rack rod two (68) is fixed on the other output shaft of the three-output shaft box (73). A mixing motor two (64) is fixed on the mixing tank two (65). Inside the mixing tank two (65), a mixing rack rod one (67) is rotatably arranged. The output shaft of the mixing motor two (64) is drivingly connected to the mixing rack rod one (67). The upper end of the mixing tank two (65) is provided with a feeding pipe (66). The material injection machine (6) includes a material injection vehicle body (75). Above the rear side of the material injection vehicle body (75), there is a vehicle handle (74). A feeding pump (76) is fixed on the material injection vehicle body (75). An inclined extrusion pipe (78) is also fixed on the material injection vehicle body (75). The lower discharging end of the extrusion pipe (78) is provided with a discharging joint (77). The upper end of the extrusion pipe (78) is fixed with a feeding hopper (79). A material injection motor (80) is fixed on the feeding hopper (79). A sealing extrusion roller is fixed on the output shaft of the material injection motor (80). The sealing extrusion roller is rotatably arranged inside the extrusion pipe (78). The output end of the feeding pump (76) is connected to the extrusion pipe (78) through a pipeline. The discharging joints (77) of the two material injection machines (6) are both connected to the feeding end of the modified foaming glue forming part (12) through polytetrafluoroethylene pipes.

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