Preparation method of high-filling PE co-extrusion wood-plastic floor

Abstract

The invention belongs to the technical field of building decoration materials, and particularly relates to a preparation method of a high-filling PE co-extrusion wood-plastic floor. According to the method disclosed by the invention, no less than 60wt% of pre-infiltrated wood powder is used in the raw materials of the surface layer, so that the wood texture and the skid resistance of the floor are improved on the premise of ensuring the mechanical property and the water resistance. In the preferable scheme, the PVC core is used, the bonding strength of the highly-filled PE surface layer and the PVC layer is improved through the MAPE welding layer, and the dimensional stability and the mechanical property after water absorption are further improved. In addition, the Tinuvin 328, the Chimassorb 944 and the rutile type titanium dioxide are matched, so that the anti-ultraviolet effect of the surface layer of the floor is improved; the fumed silica, the nanoscale alpha-aluminum oxide and the rutile type titanium dioxide are matched, so that the wear resistance of the surface layer of the floor is improved, and the problem that anti-skid textures on the surface layer of the PE wood-plastic floor are easy to wear is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of building decoration materials, and particularly relates to a preparation method of a highly filled PE co-extruded wood-plastic floor. Background Art

[0002] Wood plastic composite decking was originally specifically referred to as a board made by melting and extruding a mixture of wood powder and PE powder. With the development of technology, the plastics used are no longer limited to PE, and the fillers are no longer limited to wood powder. Classified according to the plastic matrix, it can be divided into PE-based, PVC-based, PP-based, blend-based, etc. Classified according to the fillers, it can be divided into wood-based fillers, non-wood-based fillers (such as calcium carbonate), functional fillers (metal oxides, conductive carbon black), etc. Based on the balance of product performance and cost control, the most common ones are PE-based and PVC-based. Among them, the PVC-based has the lowest cost and good water resistance, but its heat resistance and weather resistance are average. According to its properties, it is usually extruded with calcium carbonate powder to prepare indoor floors; it is also divided into rigid SPC (Stone Plastic Composite) floors and flexible sports plastic floors (more plasticizers need to be added) according to usage requirements. The PE-based has a slightly higher cost, relatively better heat resistance and weather resistance, and is usually made into outdoor floors according to its properties. In the PE-based wood-plastic floor, the higher the wood powder content, the closer the shape of the floor is to wood, but at the same time, the water absorption problem becomes more prominent, and the mechanical properties also decrease significantly. When the content of PE resin increases, the plastic texture of the floor gradually rises, and the surface becomes smoother, especially prone to causing people to slip and fall on rainy days. Therefore, there is usually an optimal range to balance various performances.

[0003] The invention patent with the application number CN 2022113076963 discloses a wood-plastic floor and its preparation method. The floor is divided into a surface layer and a bottom layer. The bottom layer uses carbonized wood powder as a filler, and the addition amount is about 65wt%, which significantly increases the usage amount of wood powder and shows good water resistance; the surface layer uses a conventional formula, and the plastic powder reaches about 60wt% to ensure mechanical properties and water resistance. However, the surface layer uses a conventional formula. Although the mechanical properties and water resistance are good, since the plastic powder reaches about 60wt%, the plastic feeling is relatively heavy and the anti-slip property is poor; in addition, due to the carbonization of the wood powder, the wood texture of the floor is missing. Summary of the Invention

[0004] To solve the above technical problems, on the one hand, the present invention provides a preparation method of a PE co-extruded wood-plastic floor. In the wood-plastic floor preparation method of the present invention, the surface layer uses a PE base. Based on the improvement of the dispersion of wood powder in PE resin, no less than 60wt% of wood powder is used, thereby improving the wood texture and anti-slip property of the floor.

[0005] The technical solution of the present invention to solve the above problems is as follows: A preparation method of a PE co-extruded wood-plastic floor, comprising the following steps: S1. Melting the first raw material to form a first melt, and pushing the first melt into the main runner of the co-extrusion die; S2. Melting the second raw material to form a second melt, and pushing the second melt into the side runner of the co-extrusion die; S3. Pushing the second melt so that it converges from the side runner into the main runner, and making it at least flow along the upper surface of the core layer precursor during the convergence process. The core layer precursor is gradually solidified from the first melt during the process of flowing towards the outlet end of the co-extrusion die in the main runner; S4. Pushing the second melt and the core layer precursor so that the second melt combines with the core layer precursor and is gradually solidified to form a surface layer precursor covering at least the upper surface of the core layer precursor during the process of flowing towards the outlet end of the co-extrusion die in the main runner, obtaining a floor precursor; S5. Simultaneously pushing the floor precursor with a material flow at the inlet end of the co-extrusion die and pulling it with a device at the outlet end of the co-extrusion die to obtain a floor; The second raw material is a mixture composed of 65-80 parts by mass of pre-infiltrated wood powder and 20-35 parts by mass of a resin premix, or a masterbatch obtained by further extrusion granulation of the mixture; The pre-infiltrated wood powder is prepared by first drying the wood powder, then spraying it with a low molecular weight polypropylene emulsion while stirring, and then heating and drying them; The resin premix contains HDPE resin and 5-10% of a compatibilizer, 3-10% of hydrated lime, 0.5-1.0% of UVA, and 0.3-0.5% of HALS based on the remaining mass; the remaining mass is the total mass excluding the pre-infiltrated wood powder; The matrix resin of the first raw material is polyolefin.

[0006] In this technical solution, the remaining mass is the total mass of the resin premix.

[0007] As a preference of the above technical solution, 3-5% of rutile titanium dioxide, 0.5-1.5% of fumed silica, and 1-2% of nano-scale α-aluminum oxide are further added to the pre-infiltrated wood powder. In this technical solution, the remaining mass is the total mass of the resin premix, rutile titanium dioxide, fumed silica, and nano-scale α-aluminum oxide.

[0008] As a preference of the above technical solution, the hydrated lime, rutile titanium dioxide, fumed silica, and nano-scale α-aluminum oxide are all surface-treated with a silane coupling agent in advance.

[0009] As a preference of the above technical solution, for the surface treatment with silane coupling agent, first prepare an aqueous solution, alcohol solution or water-alcohol mixed solution with a concentration of 5% - 25% of the silane coupling agent, and then spray the solution containing the silane coupling agent into the powder of rutile titanium dioxide, fumed silica or nano-scale α-aluminum oxide under stirring.

[0010] As a preference of the above technical solution, the compatibilizer is maleic anhydride grafted polyethylene.

[0011] As a preference of the above technical solution, the UVA is Tinuvin 328.

[0012] As a preference of the above technical solution, the HALS is Chimassorb 944.

[0013] As a preference of the above technical solution, the first raw material is a mixture composed of 65 - 80 parts by mass of pre-impregnated wood powder and 20 - 35 parts by mass of a second resin premix, or a masterbatch obtained by further extrusion granulation of the mixture; the pre-impregnated wood powder is obtained by first drying the wood powder, then spraying a low molecular weight polypropylene emulsion while stirring, and then heating them to 150 - 180 °C for drying; the second resin premix contains HDPE resin, 5 - 10% of maleic anhydride grafted polyethylene based on the remaining mass, and 5 - 10% of hydrated lime; the remaining mass is the total mass excluding the pre-impregnated wood powder.

[0014] In the second aspect, the present invention provides another method for preparing a highly filled PE co-extruded wood-plastic floor.

[0015] A method for preparing a highly filled PE co-extruded wood-plastic floor, comprising the following steps: S1. Provide a prefabricated core of the wood-plastic floor, and push the prefabricated core into the main runner of the co-extrusion die. S2. Melt maleic anhydride grafted polyethylene to form a first melt, and push the first melt into the first side runner of the co-extrusion die. S3. Push the first melt so that it converges from the first side runner into the main runner, and make it flow and spread on the peripheral surface of the prefabricated core during the convergence. S4. Push the first melt and the prefabricated core so that the first melt combines with the prefabricated core and gradually solidifies to form a welded layer covering the periphery of the prefabricated core during the flow of the main runner towards the outlet end of the co-extrusion die, obtaining a coated core. S5. Melt a second raw material to form a second melt, and push the second melt into the second side runner of the co-extrusion die. S6. Push the second melt to make it flow from the second side channel into the main channel, and make it flow and spread around the coated core during the process of merging; S7. Push the second melt and the coated core, so that the second melt combines with the coated core and gradually solidifies to form a surface precursor covering the coated core during the process of flowing towards the co-extrusion die outlet end in the main channel, obtaining a floor precursor; S8. At the same time, push the floor precursor with a material flow at the co-extrusion die inlet end and pull it with equipment at the co-extrusion die outlet end to obtain a floor; The second raw material is a mixture composed of 65 - 80 parts by mass of pre-wetted wood powder and 20 - 35 parts by mass of resin premix, or a masterbatch obtained by further extrusion granulation of the mixture; The pre-wetted wood powder is prepared by first drying the wood powder, then spraying it with a low molecular weight polypropylene emulsion while stirring, and then heating them to 150 - 180 °C for drying; The resin premix contains HDPE resin and 5 - 10% compatibilizer, 0.5 - 1.0% UVA, 0.3 - 0.5% HALS based on the remaining mass; the remaining mass is the total mass excluding the pre-wetted wood powder; The prefabricated core includes a core body and a shell layer that encloses and coats the core body from the four surfaces of up, down, left, and right; The material of the core body is rigid foamed PVC, and the material of the shell layer is low foamed or non-foamed PVC.

[0016] As a preference of the above technical solution, the thickness of the welding layer is 0.2 - 2.0 mm.

[0017] As a preference of the above technical solution, the outer surface of the shell layer is provided with a welding groove.

[0018] As a preference of the above technical solution, the prefabricated core contains the following components in mass percentage: 80 - 100 mesh wood powder 10 - 20%, Grey calcium 30 - 40%, Titanate coupling agent 1 - 3%, Calcium-zinc composite stabilizer 2 - 4%, ACR processing aid 1 - 2%, Zinc stearate 0.1 - 1%, The balance is PVC resin.

[0019] In summary, through the core layer - surface layer co-extrusion structure and the pre-wetted wood powder technology, the present invention takes into account the high wood powder filling, mechanical properties, and waterproof properties of the wood-plastic floor; and has the following beneficial effects: 1. Functional partition design: The surface layer focuses on functionality, considering waterproofing, abrasion resistance, and UV resistance; the core layer focuses on mechanical support and can be filled with low-cost fillers; the surface layer covers the core layer to avoid direct exposure of the core layer and problems such as UV degradation. 2. Pre-infiltrated wood flour process: The dried wood flour can quickly absorb the low-molecular-weight polypropylene emulsion, and then be dried by heating to 150-180 °C, so that the polypropylene emulsion absorbed by the wood flour loses the aqueous phase to form a melt that fills the inside of the wood flour and / or wraps the wood flour, and solidifies when cooled; significantly increases the amount of wood flour used without causing problems such as wood flour agglomeration and uneven dispersion in the matrix resin, improves the stability of the wood flour in the extrusion granulation process and the interfacial compatibility with the matrix resin, and improves the waterproofness of the surface layer. 3. Dynamic layered curing: The core layer and the surface layer melt are combined during flow to reduce interfacial defects. 4. MAPE is added to the matrix resin, which improves the polarity of the matrix resin, enhances the interfacial compatibility of the pre-infiltrated wood flour in the matrix resin, and enhances the interfacial compatibility of other fillers in the matrix resin. 5. The combination of Tinuvin 328, Chimassorb 944, and rutile titanium dioxide. Rutile titanium dioxide reflects light for physical blocking, Tinuvin 328 absorbs ultraviolet rays in the 300-400 nm band and converts them into heat energy, and Chimassorb 944 inhibits the photooxidation chain reaction by capturing free radicals. The three substances improve the UV resistance of the floor surface layer from three levels. 6. The combination of fumed silica, nano-scale α-aluminum oxide, and rutile titanium dioxide and their reasonable dosage ratios, pretreated with silane coupling agent, can improve the abrasion resistance of the floor surface layer on the premise of ensuring interfacial compatibility, and solve the pain point problem of non-abrasive PE wood-plastic floors. 7. The combination of fumed silica, MAPE, silane coupling agent, and wood flour pre-infiltration process significantly enhances the interfacial compatibility between materials. 8. In the second solution of the present invention, the core layer uses a PVC base; a welding layer is used to solve the problem of poor interfacial compatibility between PE and PVC; the surface layer is the same as the first solution. The PVC-based core layer can significantly increase the dosage of hydrated lime without causing compatibility problems compared with the first solution due to the difference in the matrix resin, so it also has lower cost and better water resistance. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of the wood-plastic floor in Example 1; Figure 2 is a schematic structural diagram of the wood-plastic floor in Example 2; Figure 3 is Figure 2 a partial enlarged view of; In the figure, the component names represented by each label are as follows: 1 - High - filled PE wood - plastic core 2 - High - filled PE wood - plastic surface layer 3 - Welding layer 4 - Core 41 - Shell layer 42 - PVC rigid foam core Specific implementation mode

[0021] The present invention will be further explained and illustrated below with reference to the accompanying drawings.

[0022] This specific implementation mode is only an interpretation of the present invention and does not limit the present invention. Any changes made by those skilled in the art after reading the specification of the present invention, as long as they are within the scope of the claims, will be protected by the patent law.

[0023] Example 1 A high - filled PE co - extruded wood - plastic floor, as Figure 1 shown, includes a high - filled PE wood - plastic core 1 and a high - filled PE wood - plastic surface layer 2 covering the high - filled PE wood - plastic core 1. The thickness of the high - filled PE wood - plastic core 1 is about 1 mm, and the thickness of the high - filled PE wood - plastic surface layer 2 is about 19 mm.

[0024] Specifically, the preparation method of the high - filled PE co - extruded wood - plastic floor is as follows: S1. Melt the first raw material to form a first melt, and push the first melt into the main runner of the co - extrusion die; The first raw material is specifically: pre - infiltrated wood powder∶remaining mass = 70∶30 (mass ratio); The pre - infiltrated wood powder is obtained by first drying 70 parts by mass of wood powder, then spraying with a low - molecular - weight polypropylene emulsion while stirring, and then heating them to 180 °C for drying; The second resin premix (remaining mass) contains HDPE resin, maleic anhydride - grafted polyethylene accounting for 8% of the remaining mass, and 7% of hydrated lime; the hydrated lime is pre - treated with a silane coupling agent KH - 550 (extra added outside the formula, included in the mass of hydrated lime); S2. Melt the second raw material to form a second melt, and push the second melt into the side runner of the co - extrusion die; The second raw material is specifically: pre - infiltrated wood powder∶remaining mass = 70∶30 (mass ratio); The pre - infiltrated wood powder is the same as that in step S1; Resin premix (remaining mass), comprising HDPE resin and 8% of maleic anhydride grafted modified polyethylene, 7% of lime calcium, 0.67% of Tinuvin 328, and 0.33% of Chimassorb 944; S3, pushing the second melt to make it merge into the main flow channel from the side flow channel, and making it flow on the upper surface and part of the side surface of the core layer precursor during the merging process, wherein the core layer precursor is formed by gradually solidifying the first melt in the main flow channel during the flow toward one end of the co-extrusion die outlet; S4, pushing the second melt and the core layer precursor, so that the second melt combines with the core layer precursor in the main flow channel and gradually solidifies to form a surface layer precursor covering the upper surface and part of the side surface of the core layer precursor, thereby obtaining a floor precursor; S5. At the same time, the floor precursor is pushed by a material flow at one end of the co-extrusion die inlet and pulled by a device at one end of the co-extrusion die outlet to obtain a high-filled PE co-extruded wood-plastic floor, numbered ST2025-PE-01.

[0025] The specific amounts of the raw materials used in this example are shown in Table 1.

[0026] Table 1 Material list of Example 1 Core - First Raw Material (parts by mass) Surface Layer - Second Raw Material (parts by mass) Pre - infiltrated Wood Flour 70 70 HDPE 25.5 25.2 MA - g - PE 2.4 2.4 Hydrated Lime 2.1 2.1 Tinuvin 328 (UVA) - 0.2 Chimassorb 944 (HALS) - 0.1 Example 2 The method is basically the same as Example 1, except that rutile titanium dioxide, fumed silica and nano-sized α-alumina are also added to the pre-impregnated wood powder of the second raw material. Specifically, the pre-impregnated wood powder is first prepared, and then the rutile titanium dioxide, fumed silica and nano-sized α-alumina are mixed with the pre-impregnated wood powder. The advantage of adding the functional filler to the pre-impregnated wood powder first instead of directly adding it to the resin is that it can promote their dispersion and distribution uniformity.

[0027] Specifically, the formula of the second raw material is shown in Table 2: Table 2 Material list of Example 2 Core - First Raw Material (parts by mass) Surface Layer - Second Raw Material (parts by mass) Pre - infiltrated Wood Flour 70 70 HDPE 25.5 23.2 MA - g - PE 2.4 2.4 Hydrated Lime 2.1 2.1 Rutile Titanium Dioxide - 1.2 Fumed Silica - 0.3 Nanoscale α - Alumina - 0.5 Tinuvin 328 (UVA) - 0.2 Chimassorb 944 (HALS) - 0.1 This example is a highly filled PE co-extruded wood plastic floor, numbered ST2025-PE-02.

[0028] Example 3 A highly filled PE co-extruded wood plastic floor, such as Figures 2 - 3As shown in the figure, it includes a core body 4, a welding layer 3 covering the core body, and a highly filled PE wood-plastic surface layer 2 covering the welding layer. The core body 4 includes a PVC rigid foam core 42 and a shell layer 41 that encloses and covers the PVC rigid foam core from four surfaces: top, bottom, left, and right. The density of the PVC rigid foam core 42 is about 0.8 g / cm³, and the thickness is about 15 mm. The thickness of the shell layer 41 is about 1 mm, with grooves on the surface. The groove depth is about 0.5 mm, the groove opening width is about 0.6 mm, and the groove bottom width is about 0.7 mm. The main thickness of the welding layer 3 (excluding the part embedded in the groove) is about 0.5 mm; the thickness of the highly filled PE wood-plastic surface layer 2 is about 1 mm.

[0029] The highly filled PE wood-plastic surface layer 2 is the same as that in Example 1.

[0030] The welding layer 3 is maleic anhydride grafted modified polyethylene.

[0031] Specifically, the preparation method of the highly filled PE co-extruded wood-plastic floor includes the following steps: S1. Wood powder with a mesh size of 80 - 100 is dried in an oven at 105°C for 4 hours until the moisture content < 1.5%, and surface modified with a titanate coupling agent to improve its compatibility with PVC. S2. Gray calcium powder is dried at 120°C for 2 hours and surface treated with silane coupling agent KH-550 (extra added outside the formula, included in the mass of gray calcium) to improve its compatibility with PVC. S3. Feed materials into a high-speed mixer in the following order (by mass percentage): PVC resin (43%) → calcium-zinc stabilizer (3%) → ACR processing aid (1.5%) → zinc stearate (0.5%) → modified wood powder (37%, including 35% wood powder) → activated gray calcium (15%); Mixing parameters: temperature 95°C, rotation speed 1000 rpm, time 8 minutes. S4. Extruder section control: The temperature of the twin-screw extruder (screw length-diameter ratio 44:1, equipped with a supercritical nitrogen injection system) is controlled in sections as shown in Table 3. Table 3 Temperature control table for the extruder section of Example 3 Section Temperature (°C) Function Description Feeding Section 145~150 Prevent Wood Flour Carbonization at Low Temperature Compression Section 1 Area 155~160 Initial Plasticization Compression Section 2 Area 165~170 Nitrogen Injection Point (Pressure 8 Mpa) Homogenization Section 170~175 Maintain Melt Fluidity Die Head Section 175~180 The Channel Narrows to Form a High - Pressure Area (12 Mpa) to Inhibit Pre - foaming Note: Nitrogen flow rate: 3.2 - 3.5 L / h; Temperature control: Maintain the supercritical state; S5. Die head section control: (175 - 180°C) Mold internal structure control: The initial diameter of the expansion cavity (transitioning to the pressure flow channel through an annular inclined plane) is the same as that of the pressure flow channel, and the diameter linearly expands until it becomes constant at the end (the constant section is about 150 mm). The final port diameter is about 2.5 times the initial diameter, and the total length is about 350 mm; This promotes the growth of foam cells. Temperature control: A cooling jacket is added to the rear section of the expansion cavity (to make the temperature difference between the core layer and the surface layer material flow reach more than 30 °C), and the temperature difference induces rapid cooling of the surface layer; Drawing speed: 0.8 - 1.2 m / min (If the speed is too fast, the cell growth will be uneven, and the skin layer will become thinner. The skin layer is controlled at about 1 mm); S6. Cooling section control: A sizing die and a water cooling tank are added at the die outlet to cool the skin layer to below 80 °C when it exits the sizing die, and cool the core layer slowly to 50 °C in the water cooling tank to lock the cells; Cut to obtain a prefabricated core; S7. Grooves are cut on the surface of the prefabricated core, with a groove depth of about 0.5 mm, a groove opening width of about 0.6 mm, and a groove bottom width of about 0.7 mm; S8. The prefabricated core is pushed into the main runner of the co - extrusion die; S9. Maleic anhydride - grafted polyethylene is melted to form a first melt, and the first melt is pushed into the first side runner of the co - extrusion die; S10. The first melt is pushed, so that it converges into the main runner from the first side runner, and it flows and spreads on the peripheral surface of the prefabricated core during the convergence process; S11. The first melt and the prefabricated core are pushed, so that the first melt combines with the prefabricated core and gradually solidifies to form a welded layer covering the periphery of the prefabricated core during the process of flowing towards the co - extrusion die outlet end in the main runner, obtaining a coated core; S12. The second raw material is melted to form a second melt, and the second melt is pushed into the second side runner of the co - extrusion die; The second raw material is the same as that in Example 1; S13. The second melt is pushed, so that it converges into the main runner from the second side runner, and it flows and spreads on the periphery of the coated core during the convergence process; S14. The second melt and the coated core are pushed, so that the second melt combines with the coated core and gradually solidifies to form a surface layer precursor covering the coated core during the process of flowing towards the co - extrusion die outlet end in the main runner, obtaining a floor precursor; S15. While pushing the floor precursor with a material flow at the co - extrusion die inlet end and pulling it with equipment at the co - extrusion die outlet end, a floor is obtained, numbered ST2025 - PE / PVC - 01.

[0032] Example 4 It is basically the same as Example 3, except that: in the pre-impregnated wood flour of the second raw material, rutile titanium dioxide, fumed silica and nano-scale α-aluminum oxide are also added. Specifically, the pre-impregnated wood flour is first prepared, and then rutile titanium dioxide, fumed silica and nano-scale α-aluminum oxide are mixed with the pre-impregnated wood flour. Adding the functional fillers to the pre-impregnated wood flour first instead of directly adding them to the resin has the advantage of promoting their dispersion and uniform distribution.

[0033] Specifically, the formula of the second raw material is shown in Table 2: Table 4 Bill of Materials for Example 4 Surface Layer - Second Raw Material (parts by mass) Pre - infiltrated Wood Flour 70 HDPE 23.2 MA - g - PE 2.4 Hydrated Lime 2.1 Rutile Titanium Dioxide 1.2 Fumed Silica 0.3 Nanoscale α - Alumina 0.5 Tinuvin 328 (UVA) 0.2 Chimassorb 944 (HALS) 0.1 This high-filled PE co-extruded wood-plastic floor is numbered ST2025-PE / PVC -02.

[0034] Comparative Example 1 A PE co-extruded wood-plastic floor has the same structure as that of Example 1, except that the wood-plastic formula is different. It includes a PE wood-plastic core and a PE wood-plastic surface layer covering the PE wood-plastic core. The thickness of the PE wood-plastic core is about 1 mm, and the thickness of the PE wood-plastic surface layer is about 19 mm.

[0035] Specifically, the preparation method of the PE co-extruded wood-plastic floor is as follows: S1. Melt the first raw material to form a first melt, and push the first melt into the main runner of the co-extrusion die; S2. Melt the second raw material to form a second melt, and push the second melt into the side runner of the co-extrusion die; S3. Push the second melt so that it converges from the side runner into the main runner, and make it at least flow on the upper surface of the core layer precursor during the convergence process. The core layer precursor is gradually solidified from the first melt flowing in the main runner towards the outlet end of the co-extrusion die; S4. Push the second melt and the core layer precursor so that the second melt combines with the core layer precursor and is gradually solidified to form a surface layer precursor covering at least the upper surface of the core layer precursor during the process of the second melt flowing in the main runner towards the outlet end of the co-extrusion die, obtaining a floor precursor; S5. At the same time, push the floor precursor with a material flow at the inlet end of the co-extrusion die and pull it with equipment at the outlet end of the co-extrusion die to obtain a floor, numbered ST2025-PE-D1.

[0036] The specific dosages of each raw material in Comparative Example 1 are shown in Table 5.

[0037] Table 5 Bill of Materials for Comparative Example 1 Core - First Raw Material (parts by mass) Surface Layer - Second Raw Material (parts by mass) Wood Flour 40 40 PE Wax 2 2 HDPE 53.5 53.2 MA - g - PE 2.4 2.4 Hydrated Lime 2.1 2.1 Tinuvin 328 (UVA) - 0.2 Chimassorb 944 (HALS) - 0.1 The following tests were conducted on the wood-plastic floors provided in the above Examples 1 to 4 and Comparative Example 1: 1. Water absorption test: Tested according to the water absorption test method in GB / T 17657-2013; ST2025 - PE - 01 ST2025 - PE - 02 ST2025 - PE / PVC - 01 ST2025 - PE / PVC - 02 ST2025 - PE - D1 1.82 1.81 1.81 1.81 1.7 2. Dimensional change rate after water absorption: Tested according to the dimensional change rate after water absorption test method in GB / T 24508-2020; ST2025 - PE - 01 ST2025 - PE - 02 ST2025 - PE / PVC - 01 ST2025 - PE / PVC - 02 ST2025 - PE - D1 Length Direction 0.98 0.94 0.97 0.96 1.02 Width Direction 0.18 0.18 0.17 0.16 0.20 Thickness Direction 2.56 2.55 2.54 2.53 2.70 3. Mechanical property test: Tested according to the three-point bending test method in GB / T 17657-2013; The test results are as follows: ST2025 - PE - 01 ST2025 - PE - 02 ST2025 - PE / PVC - 01 ST2025 - PE / PVC - 02 ST2025 - PE - D1 28.3 MPa 29.1 MPa 30.7 MPa 31.2 MPa 27.05 MPa As can be seen from the above table, the PE co-extruded wood-plastic floor of the present invention still exhibits good water resistance and dimensional stability after using a high filling amount of wood powder. Moreover, it also has good mechanical properties at the same time.

Claims

1. A method for preparing a highly filled PE co-extruded wood plastic floor, comprising the following steps: S1, melting a first raw material to form a first melt, and pushing the first melt into a main channel of a co-extrusion die; S2, melting the second raw material to form a second melt, and pushing the second melt into the side runner of the co-extrusion die; S3, pushing the second melt to make it merge into the main flow channel from the side flow channel, and making it at least flow on the upper surface of the core layer precursor during the merging process, wherein the core layer precursor is formed by gradually solidifying the first melt in the main flow channel during the flow toward one end of the co-extrusion die outlet; S4, pushing the second melt and the core layer precursor, so that the second melt combines with the core layer precursor in the main channel and gradually solidifies to form a surface layer precursor covering at least the upper surface of the core layer precursor in the process of flowing toward one end of the co-extrusion die outlet, thereby obtaining a floor precursor; S5, simultaneously pushing the floor precursor at one end of the co-extrusion die inlet with a material flow and pulling it at one end of the co-extrusion die outlet with a device to obtain a floor; The second raw material is a mixture of 65-80 parts by mass of pre-impregnated wood powder and 20-35 parts by mass of a resin premix, or a masterbatch obtained by further extrusion granulation of the mixture; The pre-impregnated wood powder is prepared by first drying the wood powder, then spraying the wood powder with a low molecular weight polypropylene emulsion while stirring, and then heating the wood powder to 150-180° C. and drying the wood powder; The resin premix comprises HDPE resin and 5-10% of the remaining mass of a compatibilizer, 5-10% of lime, 0.5-1.0% of UVA, and 0.3-0.5% of HALS; the remaining mass is the total mass excluding the pre-impregnated wood powder; The base resin of the first raw material is polyolefin.

2. The method for preparing a highly filled PE co-extruded wood plastic floor according to claim 1, characterized in that: The pre-impregnated wood powder is further added with 3-5% of the remaining mass of rutile titanium dioxide, 0.5-1.5% of fumed silicon dioxide and 1-2% of nano-grade α-alumina.

3. The method for preparing a highly filled PE co-extruded wood plastic floor according to claim 2, characterized in that: The limestone, rutile titanium dioxide, fumed silica and nano-scale alpha-alumina are all surface-treated with a silane coupling agent in advance.

4. The method for preparing a highly filled PE co-extruded wood plastic floor according to claim 3, characterized in that: The surface treatment with silane coupling agent is to first prepare the silane coupling agent into a 5% to 25% concentration aqueous solution, alcohol solution or water-alcohol mixed solution, and then spray the solution containing the silane coupling agent into the rutile titanium dioxide, fumed silica or nano-grade α-alumina powder under stirring.

5. The method for preparing a highly filled PE co-extruded wood plastic floor according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted modified polyethylene.

6. The method for preparing a highly filled PE co-extruded wood plastic floor according to claim 1, characterized in that: The UVA is Tinuvin 328.

7. The method for preparing a highly filled PE co-extruded wood plastic floor according to claim 1, characterized in that: The HALS is Chimassorb 944.

8. A method for preparing a highly filled PE co-extruded wood plastic floor, comprising the following steps: S1, providing a prefabricated core of the wood plastic floor, and pushing the prefabricated core into the main channel of the co-extrusion mold; S2, melting the maleic anhydride grafted modified polyethylene to form a first melt, and pushing the first melt into a first side flow channel of a co-extrusion die; S3, pushing the first melt to make it merge into the main flow channel from the first side flow channel, and making it flow on the surrounding surface of the prefabricated core during the merging process; S4, pushing the first melt and the prefabricated core, so that the first melt combines with the prefabricated core in the main channel while flowing toward one end of the co-extrusion die outlet and gradually solidifies to form a fusion layer covering the periphery of the prefabricated core, thereby obtaining a coated core; S5, melting the second raw material to form a second melt, and pushing the second melt into a second side flow channel of the co-extrusion mold; S6, pushing the second melt to make it merge into the main flow channel from the second side flow channel, and making it flow around the clad core during the merging process; S7, pushing the second melt and the coating core, so that the second melt combines with the coating core in the process of flowing toward one end of the co-extrusion die outlet in the main channel and gradually solidifies to form a surface layer precursor covering the coating core, thereby obtaining a floor precursor; S8, simultaneously pushing the floor precursor at one end of the co-extrusion die inlet with a material flow and pulling it at one end of the co-extrusion die outlet with a device to obtain a floor; The second raw material is a mixture of 65-80 parts by mass of pre-impregnated wood powder and 20-35 parts by mass of a resin premix, or a masterbatch obtained by further extrusion granulation of the mixture; The pre-impregnated wood powder is prepared by first drying the wood powder, then spraying the wood powder with a low molecular weight polypropylene emulsion while stirring, and then heating the wood powder to 150-180° C. and drying the wood powder; The resin premix comprises HDPE resin and 5-10% of the remaining mass of a compatibilizer, 0.5-1.0% of UVA, and 0.3-0.5% of HALS; the remaining mass is the total mass excluding the pre-impregnated wood powder; The prefabricated core comprises a core body and a shell layer that seals and covers the core body from four surfaces: top, bottom, left and right; The material of the core is hard foamed PVC, and the material of the shell is low-foamed or non-foamed PVC.

9. The method for preparing a highly filled PE co-extruded wood plastic floor according to claim 8, characterized in that: The thickness of the welding layer is 0.2-2.0 mm.

10. The method for preparing a highly filled PE co-extruded wood plastic floor according to claim 8, characterized in that: The prefabricated core comprises the following components in percentage by mass: 80~100 mesh wood powder 10~20%, Ash calcium 30~40%, Titanate coupling agent 1~3%, Calcium zinc composite stabilizer 2~4%, ACR processing aid 1~2%, Zinc stearate 0.1~1%, The balance is PVC resin.

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