Wood-plastic co-extruded wood-plastic ribbed co-extruded profile and method for producing same

Abstract

This invention discloses a wood-plastic co-extruded profile with a textured pattern and its preparation method. The profile is produced by co-extruding a core layer and a surface layer. By adding color powder and textured masterbatch to the surface layer, combined with a special feeding process, the extruded profile can produce random stripes, more closely resembling the texture of natural wood. Maleic anhydride-grafted polyethylene is added as a compatibilizer to both the core layer and the surface layer, significantly improving the interfacial bonding between wood flour or reed powder and the plastic matrix, and increasing peel strength. The core layer uses recycled HDPE as the matrix, reducing production costs and conforming to the concept of a circular economy. The profile produced by this invention has good dimensional stability, a bending strength of over 25 MPa, a surface electrostatic voltage of no more than 3 kV, and after 3000 hours of accelerated artificial aging, the product appearance shows no significant change, and the mechanical property retention rate exceeds 90%.

Description

Technical Field

[0001] This invention relates to the field of wood-plastic composite materials technology, and in particular to a wood-plastic co-extruded wood-plastic flow textured co-extruded profile and its preparation method. Background Technology

[0002] In existing technologies, co-extruded profiles with a pure plastic surface are mainly produced through a multi-layer plastic co-extrusion process. Although they possess certain mechanical properties, they suffer from the following significant drawbacks: Insufficient wood-like texture: The surface of the pure plastic co-extruded profiles is smooth, lacking the texture and feel of natural wood, resulting in a monotonous visual effect that fails to meet the demands of the high-end architectural decoration market for natural aesthetics. According to industry research, over 70% of consumers believe that the appearance simulation of existing pure plastic co-extruded products is insufficient.

[0003] Poor adhesion between the core and surface layers: The core and surface pure plastic materials of traditional co-extruded profiles with pure plastic surfaces have limited compatibility, resulting in insufficient interlayer bonding. Under long-term use or environmental stress, delamination and peeling are prone to occur. JC / T2781-2023 standard tests show that the peel strength of co-extruded profiles with pure plastic surfaces is generally lower than that of wood-plastic co-extruded wood-plastic products.

[0004] Insufficient environmental performance: Co-extruded profiles with a pure plastic surface mainly rely on virgin plastic raw materials, resulting in high resource consumption and failing to align with current green environmental protection and circular economy development concepts. In contrast, wood-plastic co-extruded wood-plastic composites can efficiently utilize agricultural and forestry waste and recycled plastics, offering significant environmental advantages.

[0005] Excessive surface static charge: Wood-plastic co-extruded flooring poses a significant risk of static electricity accumulation during production and use. Surface static voltage testing under standard conditions (temperature 23℃, relative humidity 50%) shows that the peak surface static charge can reach 10.6-12.6kV, far exceeding the recommended safe static electricity threshold for ordinary residential building materials (typically ≤3kV). The specific impacts of this characteristic include: 1. Production and processing risks: In processes such as floor cutting, grooving, and lamination, high static electricity can easily attract a large amount of dust and debris, which not only affects the precision of surface coating and embossing processes, but may also cause fire and explosion hazards in workshop environments with high dust concentrations; at the same time, electrostatic discharge may interfere with the sensor precision of CNC machining equipment, leading to an increase in the defect rate.

[0006] 2. Potential hazards in usage scenarios: In the dry winters of northern China and in enclosed office environments where air conditioning is constantly on, electrostatic discharge generated by friction from people walking around can cause a noticeable electric shock, reducing the user experience; in scenarios such as computer rooms and laboratories where electronic equipment is densely packed, 10kV-level electrostatic discharge may damage precision electronic components, causing equipment failure or data loss.

[0007] 3. Daily maintenance drawbacks: The high static electricity properties make the floor easily attract dust and hair from the air, requiring more frequent cleaning and maintenance. In addition, ordinary dry cleaning methods can actually exacerbate static electricity accumulation and increase long-term maintenance costs.

[0008] Wood-plastic composites (WPC) are composite materials made by filling thermoplastic plastics with plant fibers and forming them through processing methods such as extrusion, lamination, molding or injection molding. They combine the ecological characteristics of wood with the reprocessable properties of thermoplastic polymers.

[0009] Wood-plastic co-extrusion technology, as a processing method to improve material properties, has been applied in the field of wood-plastic composites. Wood-plastic composites with a multi-layered core-surface structure use traditional wood-plastic composites as the core layer, with a functional co-extruded surface layer coating the top, giving the material superior performance. In recent years, Chinese research institutions and manufacturing companies have successively launched co-extrusion technologies or products, and co-extruded wood-plastic composites are currently entering a period of rapid development. However, existing technologies still struggle to simultaneously solve the dual problems of wood-like texture and adhesion, necessitating an innovative technical solution. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides a wood-plastic co-extruded wood-plastic textured co-extruded profile and its preparation method. By designing the material formulation and optimizing the process parameters, the co-extruded profile with excellent wood texture and high bonding strength can be produced.

[0011] To achieve this technical objective, the present invention adopts the following solution: In a first aspect, the present invention provides a method for preparing a wood-plastic co-extruded wood-plastic textured co-extruded profile, comprising the following steps: Prepare the core layer and surface layer materials: The core layer material, by weight, includes: 26-35 parts recycled HDPE, 48-52 parts wood flour or reed powder, 2-5 parts maleic anhydride grafted polyethylene, 1.5-3 parts lubricant, 1-3 parts talc, and 0.1-0.3 parts antioxidant; The surface layer material, by weight, includes: 35-52 parts virgin HDPE, 25-48 parts wood flour or reed powder, 2-5 parts maleic anhydride grafted polyethylene, 3-5 parts lubricant, 4-6 parts color powder, 0.2-0.5 parts antioxidant, 0.2-0.5 parts UV absorber, and 2-4 parts flow pattern masterbatch. The core material is extruded using a 65 / 132 conical twin-screw extruder, and the surface material is extruded using a 45 / 100 conical twin-screw extruder or a φ45 single-screw extruder as a co-extruder. The core and surface materials are then combined and molded using a co-extrusion die, with a co-extrusion layer thickness of 1~1.5mm. The temperature settings for the 65 / 132 conical twin-screw extruder are as follows: Zone 1 185~195℃, Zone 2 170~190℃, Zone 3 125~150℃, Zone 4 125~150℃, and the confluence core 120~140℃. The temperature settings for the 45 / 100 conical twin-screw extruder are: Zone 1 180~200℃, Zone 2 175~190℃, Zone 3 165~180℃, and Zone 4 165~180℃. The φ45 single-screw extruder is equipped with a drying hopper. The temperature settings of the φ45 single-screw extruder are: Zone 1 155~170℃, Zone 2 165~180℃, Zone 3 175~190℃, and Zone 4 180~190℃.

[0012] The core layer material primarily provides structural support. Using recycled HDPE (high-density polyethylene) as the main matrix material not only reduces production costs but also aligns with the principles of a circular economy. The wood flour or reed flour content is controlled within a high proportion range of 48-52 parts, ensuring the rigidity and dimensional stability of the profile and reducing the coefficient of expansion. Maleic anhydride-grafted polyethylene acts as a compatibilizer; the maleic anhydride groups in its molecular chain can undergo esterification with the hydroxyl groups on the surface of the wood flour or reed flour. Simultaneously, the polyethylene segments have good compatibility with the HDPE matrix, significantly improving the interfacial bonding between the wood flour or reed flour and the plastic matrix, thus enhancing the material's mechanical properties. The addition of lubricants improves processing flowability and reduces energy consumption during extrusion. Talc acts as a filler and reinforcing agent, ensuring the dimensional stability of the profile. Antioxidants enhance processing stability and durability.

[0013] The surface layer primarily serves decorative and protective functions, using virgin HDPE as the matrix material to ensure surface smoothness and weather resistance. The wood flour or reed content is relatively low compared to the core layer (25-48 parts), balancing the wood-like texture with processing performance. Maleic anhydride-grafted polyethylene also acts as a compatibilizer, ensuring uniformity within the surface material. The lubricant content is higher than in the core layer (3-5 parts), which not only improves processing flowability but also promotes the formation of flow lines. Pigment provides the basic hue, while flow line masterbatch is the key component for achieving the wood-like texture; its uneven distribution during extrusion creates random striped textures, mimicking the effect of natural wood grain. Antioxidants enhance processing stability and durability. UV absorbers are used to extend the profile's lifespan.

[0014] Furthermore, the wood flour or reed flour is 80-100 mesh with a moisture content of less than 6%; the grafting rate of maleic anhydride-grafted polyethylene is 0.8-1.2%.

[0015] Furthermore, the lubricant is one or more of stearic acid, stearate, butyl stearate, oleamide, ethylene bis-stearamide, or polyethylene wax / stearic acid composite lubricant; the colorant is one or more of iron oxide red, iron oxide yellow, iron oxide black, or carbon black.

[0016] Furthermore, the antioxidant is antioxidant 168 or antioxidant 1010; the ultraviolet additive is at least one of light stabilizer 744, light stabilizer GW-540, light stabilizer AM-101, ultraviolet absorber UV-531, and ultraviolet absorber UV-9.

[0017] Furthermore, the flow pattern masterbatch is a mixture of PP resin, PE resin, color powder and functional additives, with 20-45 parts of PP resin, 30-60 parts of PE resin, 15-50 parts of color powder and 0-6 parts of functional additives by mass. The color powder is one or more of iron oxide red, iron oxide yellow, iron oxide black or carbon black. The functional additives include antioxidants and ultraviolet additives.

[0018] Furthermore, the screw speed of the 65 / 132 conical twin-screw extruder is 0~40 r / min, and the main motor power is 37 kW; the screw speed of the 45 / 100 conical twin-screw extruder is 0~45 r / min, and the main motor power is 15 kW; the screw speed of the φ45 single-screw extruder is 0~60 r / min, and the main motor power is 11 kW.

[0019] Furthermore, the 65 / 132 conical twin-screw extruder and the 45 / 100 conical twin-screw extruder are equipped with a φ25 single-screw extruder at the feed port for feeding lubricant; the 45 / 100 conical twin-screw extruder is equipped with a φ20 single-screw side feeder and an agricultural seeder at the feed port for feeding flow pattern masterbatch.

[0020] Furthermore, the 65 / 132 conical twin-screw extruder for the core layer is equipped with a φ25 single-screw extruder at the feed port for feeding lubricant; after the lubricant, flow pattern masterbatch and surface material are mixed, they are fed into the φ45 single-screw extruder for the surface layer co-extrusion in one go.

[0021] Furthermore, the core layer extrusion speed is 0.5~1.2 m / min to ensure core layer structural stability, while the surface layer co-extrusion speed is 0.6~1.5 m / min, slightly higher than the core layer speed, to ensure complete coverage. The traction speed is 0.5~1.3 m / min, matched to the extrusion speed to prevent deformation. The matching of extrusion speeds directly affects the uniformity and flow pattern effect of the co-extruded layer. The speed difference between the core layer and the surface layer is controlled within the range of 0.1~0.3 m / min to ensure good coverage while generating appropriate shear force to promote flow pattern formation.

[0022] The core extrusion system employs a 65 / 132 conical twin-screw extruder with a tapered, counter-rotating twin-screw design. The screw diameter gradually changes from 65mm at the small end to 132mm at the large end. This design allows the material depth within the screw channels to gradually decrease, facilitating material compression and degassing. The length-to-diameter ratio is controlled within the range of 16~18:1, ensuring sufficient plasticization and mixing. The main motor is a 37kW permanent magnet motor with a high-torque design. The gears and shafts are made of high-strength alloy steel and have undergone carburizing and gear grinding treatments to ensure the stability of the equipment under high-speed operation. The screw speed range is 0~40r / min, which can be flexibly adjusted according to production needs. The barrel uses an infrared heater and cooling fan, with a temperature control accuracy of ±1℃. The temperature of each section is precisely set according to the material characteristics. A vacuum degassing system is also equipped to effectively remove volatiles and moisture from the material, improving product quality.

[0023] The surface co-extrusion system can utilize a 45 / 100 conical twin-screw extruder, with screw diameters ranging from 45mm at the small end to 100mm at the large end, an L / D ratio of 16~18:1, a main motor power of 15kW, and a screw speed range of 0-45r / min. It is suitable for large-scale production, provides good mixing, and is well-suited for surface materials with high wood flour content.

[0024] This invention adds a φ25 single-screw extruder at the feed inlet of a conical twin-screw extruder, specifically for feeding lubricant. This system employs precise metering control to ensure that the lubricant is added uniformly and stably to the main extruder, promoting flow pattern formation.

[0025] This invention uses a φ20 single screw as a side feeder or agricultural seeder for feeding masterbatch. The system has the following features: it adopts a modular design and unique SFT technology, which can meet the feeding needs of different materials; the coordination between the mixing paddle and the feeding screw achieves uniform material supply; and the feeding amount can be precisely controlled to ensure the stability of the flow pattern effect.

[0026] The surface co-extrusion system can also utilize a φ45 single-screw extruder with a screw diameter of 45mm, a length-to-diameter ratio of 25:1, a main motor power of 11kW, and a screw speed range of 0-60r / min. When using a φ45 single-screw extruder, a drying hopper needs to be added to ensure the raw materials are dry and prevent moisture from affecting product quality. The lubricant, flow pattern masterbatch, and surface material are mixed and then fed into the φ45 single-screw extruder in one go. This approach simplifies equipment configuration. Pre-mixing in the mixer ensures that the lubricant and flow pattern masterbatch are evenly distributed in the surface material, forming random striped textures during extrusion. This method is suitable for small-batch, multi-variety production, with lower equipment investment and simple operation.

[0027] This invention features precise temperature control in four zones: Zone 1 is the feeding zone, where the material is preheated and begins to soften; Zone 2 is the compression zone, where the material is compressed and initially plasticized; Zone 3 is the metering zone, where the material is further plasticized and uniformly mixed; and Zone 4 is the homogenization zone, where final plasticization and stable flow are achieved. The core layer extrusion temperature is relatively low, primarily to protect the wood flour components and prevent thermal degradation; while the surface layer co-extrusion temperature is relatively high, which is beneficial for the formation of flow lines and improved surface quality. When using a φ45 single-screw extruder, a drying hopper must be added to ensure the raw material is dry and to prevent moisture from forming bubbles at high temperatures, which would affect surface quality.

[0028] The thickness of the co-extruded layer is a crucial parameter affecting product performance and cost. In this invention, the thickness of the co-extruded layer is controlled within the range of 1~1.5mm. This thickness setting is based on considerations of performance requirements, cost control, and flow pattern effects: sufficient thickness ensures surface weather resistance and wear resistance; while meeting performance requirements, the use of virgin materials is minimized; and appropriate thickness is beneficial for the formation and expression of flow patterns.

[0029] The runner design of the co-extrusion die in this invention is the same as that of pure plastic co-extrusion, but the co-extrusion layer thickness needs to be increased to 1~1.5mm to ensure good bonding between the core layer and the surface layer. The die adopts a split mandrel design to simplify the maintenance process; it is equipped with a circulating water cooling system to speed up the molding cycle; and it adopts a corrosion-resistant design to extend the die life.

[0030] Secondly, the present invention provides a wood-plastic co-extruded wood-plastic textured co-extruded profile prepared by the aforementioned method. The profile has a random striped texture, a peel strength of not less than 3.5 MPa, a flexural strength of not less than 25 MPa, a water absorption rate of less than 1.5%, and a surface electrostatic voltage of ≤3 kV. After artificial accelerated aging for 3000 hours, there is no significant change in appearance, and the mechanical properties retain more than 90%.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Significantly Enhanced Wood-like Texture: This invention adds 4-6 parts color powder and 2-4 parts flow-pattern masterbatch to the surface material, combined with a special feeding process, enabling the extruded profiles to produce random striped patterns, more closely resembling the texture of natural wood. Market research shows that 92% of consumers approve of the wood-like texture of the product, far exceeding the 65% approval rate for traditional surface-layer pure plastic co-extruded profiles. The flow-pattern masterbatch, through a specially formulated design, forms irregular flowing textures during extrusion, simulating the grain effect of natural wood, significantly enhancing the product's visual appeal and market competitiveness.

[0032] 2. Significantly Enhanced Adhesion Between Core and Surface Layers: This invention significantly improves the interfacial bonding between wood flour or reed powder and the plastic matrix by adding 2-5 parts of maleic anhydride-grafted polyethylene as a compatibilizer to both the core and surface layers. According to JC / T2781-2023 "Test Method for Peel Strength of Surface and Substrate Layers of PE Co-extruded Wood-Plastic Composites", the peel strength of the product of this invention reaches 3.5 MPa, which is approximately 60% higher than that of traditional pure plastic co-extruded profiles. The maleic anhydride groups in the maleic anhydride-grafted polyethylene molecular chain can undergo esterification with the hydroxyl groups on the surface of wood flour and reed powder. Simultaneously, the polyethylene segments have good compatibility with the HDPE matrix, forming a strong interfacial bond and effectively preventing delamination and peeling.

[0033] 3. Significantly Improved Resource Utilization Efficiency: The core layer material of this invention uses 26-35 parts recycled HDPE, which not only reduces production costs but also aligns with the principles of a circular economy. Compared to traditional co-extruded profiles with pure plastic surface layers, this invention reduces the amount of virgin plastic used by approximately 20%, while simultaneously increasing the utilization rate of agricultural and forestry waste (wood flour or reed flour). According to economic analysis, the production cost of this invention is reduced by approximately 15% compared to traditional technologies, demonstrating significant economic benefits and environmental value.

[0034] 4. Overall product performance has been comprehensively improved. The profile products of this invention, while maintaining an excellent wood-like texture, also have the following performance advantages: Weather resistance: The surface layer of new HDPE and the appropriate co-extruded layer thickness (1~1.5mm) provide good weather resistance. According to GB / T29365 "Test method for anti-aging performance of wood-plastic composites for building", after artificial accelerated aging for 3000 hours, the product appearance has no obvious changes and the mechanical properties retain more than 90%.

[0035] Mechanical properties: Optimized material formulation and interfacial compatibility give the product excellent mechanical properties, with a bending strength of over 25 MPa, which is about 10% higher than that of traditional wood-plastic composites.

[0036] Dimensional stability: The high content of wood flour or reed flour and good interfacial bonding give the product a low water absorption rate and water absorption thickness expansion rate, significantly improving dimensional stability.

[0037] Low surface electrostatic voltage: The surface electrostatic voltage of the wood-plastic co-extruded wood-plastic flow textured co-extruded profile of this invention is only 2.01kV under standard environment (23℃, relative humidity 50%), which is far lower than the electrostatic level of traditional co-extruded wood-plastic materials and ordinary indoor building materials. Attached Figure Description

[0038] Figure 1 This refers to the co-extruded profile produced in Embodiment 1 of the present invention.

[0039] Figure 2 This refers to the co-extruded profile produced in Embodiment 2 of the present invention.

[0040] Figure 3 This is the co-extruded profile produced in Comparative Example 1 of the present invention.

[0041] Figure 4 This is the co-extruded profile in Comparative Example 2 of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0043] Unless otherwise specified, the experimental methods used in the embodiments and comparative examples of this invention are conventional methods. Unless otherwise specified, the materials and reagents used are commercially available. Example 1

[0044] 1. Prepare core material and surface material Core material: 30 parts recycled HDPE, 50 parts wood flour (80 mesh, 6% moisture content), 3 parts maleic anhydride grafted polyethylene (grafting rate 1.0%), 3 parts talc, 0.3 parts antioxidant (antioxidant 1010), and 2 parts lubricant (polyethylene wax / stearic acid composite lubricant). Surface material: 45 parts new HDPE, 35 parts wood flour (100 mesh, 6% moisture content), 3 parts maleic anhydride grafted polyethylene (grafting rate 1.0%), 4 parts lubricant (polyethylene wax / stearic acid composite lubricant), 0.5 parts antioxidant (antioxidant 1010), 0.5 parts ultraviolet absorber (UV-531), 5 parts color powder (iron oxide red), 3 parts flow pattern masterbatch (30 parts PP resin + 40 parts PE resin + 30 parts iron oxide red + 1 part antioxidant 1010 + 1 part ultraviolet absorber UV-531).

[0045] 2. Equipment configuration and process parameters Core extruder: 65 / 132 conical twin-screw extruder, main motor power 37kW; Core extrusion temperature settings: Zone 1 190℃, Zone 2 180℃, Zone 3 140℃, Zone 4 140℃, and confluence core 130℃. Surface co-extrusion machine: 45 / 100 conical twin-screw extruder, main motor power 15kW; Surface co-extrusion temperature settings: Zone 1 190℃, Zone 2 185℃, Zone 3 175℃, Zone 4 175℃; Lubricant feeding device: φ25 single screw extruder, installed at the discharge port of conical twin screw extruder; Flow pattern masterbatch feeding device: φ20 single screw side feeder and agricultural seeder; Co-extrusion die: The runner design is the same as that of traditional surface pure plastic co-extrusion runner, and the co-extrusion layer thickness is 1.2mm; Auxiliary equipment: drying hopper, cooling and shaping table, traction machine, cutting machine.

[0046] Extrusion speed control: core layer extrusion speed 0.5 m / min, surface layer co-extrusion speed 0.6 m / min, traction speed 0.5 m / min.

[0047] 3. Production process Raw material pretreatment: Mix all components of the core material except lubricant in a high-speed mixer for 10 minutes according to the proportion; mix all components of the surface material except lubricant and flow pattern masterbatch in a high-speed mixer for 10 minutes according to the proportion; granulate the mixed core material and surface material separately using a parallel twin-screw granulator to fully melt the plastic with wood flour or reed powder, crush them into uniform particles by a crushing blower, and then transport them to a homogenization silo for later use.

[0048] Extrusion preparation: Start the core extruder (65 / 132 conical twin-screw extruder), heat to the set temperature, and start the screw after the temperature stabilizes, setting the speed to 25 r / min; start the surface co-extruder (45 / 100 conical twin-screw extruder), heat to the set temperature, and start the screw after the temperature stabilizes, setting the speed to 30 r / min; start the lubricant feeding device (φ25 single-screw extruder), setting the speed to 15 r / min; start the flow pattern masterbatch feeding device, setting the speed of the φ20 single-screw side feeder to 10 r / min, and the speed of the agricultural seeder to 25 r / min.

[0049] Co-extrusion molding: The core layer granules are added to the hopper of the core layer extruder, and the surface layer granules are added to the hopper of the surface layer co-extruder. Lubricant is added through the lubricant feeding device, and flow pattern masterbatch is added through the flow pattern masterbatch feeding device. Extrusion begins, and the extrusion speed is adjusted to make the core layer and surface layer melts merge in the co-extrusion die to form a co-extrusion structure. The profile is cooled and shaped by a vacuum shaping table.

[0050] Post-processing: The traction machine pulls the profile cutting machine at a set speed to cut the profile to the set length. The appearance and dimensions of the product are inspected, and qualified products are packaged and put into storage.

[0051] 4. Product Performance The performance of the profile products produced in this embodiment was tested, and the results are as follows: Appearance: The surface has a random striped texture, with a strong wood feel, closely resembling the effect of natural wood; Peel strength: 3.6 MPa (tested according to GB / T 24508-2020); Bending strength: 31.99 MPa (tested according to GB / T 24508-2020); Water absorption rate: 1.2% (after 24 hours of soaking, tested according to GB / T 24508-2020); Surface electrostatic voltage: 5.5kV, which decreases to 2.01kV after being left to stand at room temperature for one month; After 3000 hours of artificial accelerated aging (xenon lamp aging), there was no significant change in appearance, and the mechanical properties were retained at a rate of over 90%. Example 2

[0052] 1. Prepare core material and surface material Core material: 35 parts recycled HDPE, 48 parts wood flour and reed powder mixture (80 mesh, 4% moisture content), 2 parts maleic anhydride grafted polyethylene (grafting rate 0.9%), 3 parts talc, 0.3 parts antioxidant (antioxidant 168), and 1.5 parts lubricant (butyl stearate). Surface material: 40 parts new HDPE, 40 parts wood flour and reed powder mixture (100 mesh, 4% moisture content), 5 parts maleic anhydride grafted polyethylene (grafting rate 0.9%), 5 parts lubricant (butyl stearate), 0.5 parts antioxidant (antioxidant 168), 0.5 parts ultraviolet absorber (UV-9), 6 parts color powder (iron oxide black), 2 parts flow pattern masterbatch (40 parts PP resin + 50 parts PE resin + 25 parts iron oxide black + 2 parts antioxidant 168 + 2 parts ultraviolet absorber UV-9).

[0053] 2. Equipment configuration and process parameters Core extruder: 65 / 132 conical twin-screw extruder, main motor power 37kW; Core extrusion temperature settings: Zone 1 185℃, Zone 2 170℃, Zone 3 125℃, Zone 4 125℃, and confluence core 120℃. Surface co-extrusion machine: φ45 single screw extruder, main motor power 15kW, equipped with drying hopper; Surface co-extrusion temperature settings: Zone 1 160℃, Zone 2 170℃, Zone 3 180℃, Zone 4 185℃; Lubricant feeding device: φ25 single screw extruder, installed at the discharge port of conical twin screw extruder; Co-extrusion die: The runner design is the same as that of traditional surface pure plastic co-extrusion runner, and the co-extrusion layer thickness is 1.5mm; Auxiliary equipment: drying hopper, cooling and shaping table, traction machine, cutting machine.

[0054] Extrusion speed control: core layer extrusion speed 0.5 m / min, surface layer co-extrusion speed 0.6 m / min, traction speed 0.5 m / min.

[0055] 3. Production process Raw material pretreatment: All components of the core layer material, except for the lubricant, are mixed in a high-speed mixer for 10 minutes according to the specified ratio. All components of the surface layer material, except for the lubricant and flow pattern masterbatch, are mixed in a high-speed mixer for 10 minutes according to the specified ratio. The mixed core layer and surface layer materials are then granulated separately using a parallel twin-screw granulator to ensure complete melting of the plastic with wood flour or reed powder. The granules are then crushed into uniform particles by a crushing blower and conveyed to a homogenization silo for later use. The surface layer particles are then mixed with the lubricant and flow pattern masterbatch in a mixer for 15 minutes according to the specified ratio to ensure uniform distribution.

[0056] Extrusion preparation: Start the core extruder (65 / 132 conical twin-screw extruder), heat up to the set temperature, and start the screw after the temperature stabilizes, setting the speed to 20 r / min; start the surface co-extruder (φ45 single-screw extruder), heat up to the set temperature, and start the screw after the temperature stabilizes, setting the speed to 25 r / min; start the lubricant feeding device (φ25 single-screw extruder), setting the speed to 15 r / min.

[0057] Co-extrusion molding: The core layer granules are added to the hopper of the core layer extruder, and the surface layer granules are added to the hopper of the surface layer co-extruder. Lubricant is added through the lubricant feeding device, and extrusion begins. The extrusion speed is adjusted so that the core layer and surface layer melts merge in the co-extrusion die to form a co-extrusion structure. The profile is cooled and shaped by a vacuum shaping table.

[0058] Post-processing: The traction machine pulls the profile cutting machine at a set speed to cut the profile to the set length. The appearance and dimensions of the product are inspected, and qualified products are packaged and put into storage.

[0059] 4. Product Performance The performance of the profile products produced in this embodiment was tested, and the results are as follows: Appearance: The surface has a random striped texture, with a strong wood feel, closely resembling the effect of natural wood; Peel strength: 3.8 MPa (tested according to GB / T 24508-2020); Bending strength: 34.56 MPa (tested according to GB / T 24508-2020); Water absorption rate: 1.0% (after 24 hours of soaking, tested according to GB / T 24508-2020); Surface electrostatic voltage: 5.9kV, reduced to 2.32kV after standing at room temperature for one month; After 3000 hours of artificial accelerated aging (xenon lamp aging), there was no significant change in appearance, and the mechanical properties were retained at a rate of over 90%. Comparative Example 1

[0060] The traditional two-step co-extrusion molding process is adopted.

[0061] 1. Prepare core material and surface material Core material: 28 parts recycled HDPE granules, 50 parts wood flour (80 mesh, 6% moisture content), 3 parts maleic anhydride grafted polyethylene (grafting rate 1.0%), and 2 parts lubricant (polyethylene wax / stearic acid composite lubricant). Surface material: 92 parts of brand new HDPE granules and 8 parts of special color masterbatch.

[0062] 2. Equipment configuration and process parameters Core extruder: 65 / 132 conical twin-screw extruder, screw speed set at 25 r / min; Core extrusion temperature settings: feeding section 155℃, plasticizing section 170℃, homogenizing section 170℃, die head 165℃; Surface co-extrusion machine: φ35 single screw co-extrusion machine (side feed), screw speed set to 40r / min; Surface co-extrusion temperature settings: barrel 155℃, die head 160℃; Co-extrusion die: The runner design is a traditional surface pure plastic co-extrusion runner, and the co-extrusion layer thickness is 0.5mm; Auxiliary equipment: drying hopper, cooling and shaping table, traction machine, cutting machine.

[0063] Extrusion speed control: core layer extrusion speed 0.5 m / min, surface layer co-extrusion speed 0.6 m / min, traction speed 0.5 m / min.

[0064] 3. Production process Raw material pretreatment: mix wood flour and maleic anhydride grafted polyethylene compatibilizer in the core material at high speed for 3 minutes, then add recycled HDPE granules and lubricant and mix for 5 minutes. Extrude and granulate for later use. Co-extrusion molding: The core layer granules are added to the hopper of the core layer extruder, and the surface layer material is added to the hopper of the surface co-extruder. Extrusion begins. The extrusion speed is adjusted so that the core layer and surface layer melts merge in the co-extrusion die to form a co-extrusion structure. The profile is cooled and shaped by a vacuum shaping table.

[0065] Post-processing: The traction machine pulls the profile cutting machine at a set speed to cut the profile to the set length. The appearance and dimensions of the product are inspected, and qualified products are packaged and put into storage.

[0066] 4. Product Performance The performance of the profile products produced in this comparative example was tested, and the results are as follows: Appearance: The surface has random striped texture, the color is very uniform, and the wood texture is poor; Peel strength: 2.6 MPa (tested according to GB / T 24508-2020); Bending strength: 22.36 MPa (tested according to GB / T 24508-2020); Water absorption rate: 1.3% (after 24 hours of soaking, tested according to GB / T 24508-2020); Surface electrostatic voltage: 12.6kV, which drops to 10.6kV after standing at room temperature for one month; After 3000 hours of artificial accelerated aging (xenon lamp aging), there was no significant change in appearance, and the mechanical properties were retained at 85%. Comparative Example 2

[0067] This comparison uses commercially available ordinary co-extruded flooring as an example. Performance tests were conducted on it, and the results are as follows: Appearance: The surface has random striped texture and poor wood feel; Peel strength: 3.3 MPa (tested according to GB / T 24508-2020); Bending strength: 20.9 MPa (tested according to GB / T 24508-2020); Water absorption rate: 1.2% (after 24 hours of soaking, tested according to GB / T 24508-2020); Surface electrostatic voltage: 19.8kV, which decreased to 12.9kV after being left to stand at room temperature for one month. After 3000 hours of artificial accelerated aging (xenon lamp aging), there was no significant change in appearance, and the mechanical properties were retained at 85%.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should all be considered to be within the protection scope of the present invention.

Claims

1. A method for preparing a wood-plastic co-extruded wood-plastic textured co-extruded profile, characterized in that, Includes the following steps: Prepare the core layer and surface layer materials: The core layer material, by weight, includes: 26-35 parts recycled HDPE, 48-52 parts wood flour or reed powder, 2-5 parts maleic anhydride grafted polyethylene, 1.5-3 parts lubricant, 1-3 parts talc, and 0.1-0.3 parts antioxidant; The surface layer material, by weight, includes: 35-52 parts virgin HDPE, 25-48 parts wood flour or reed powder, 2-5 parts maleic anhydride grafted polyethylene, 3-5 parts lubricant, 4-6 parts color powder, 0.2-0.5 parts antioxidant, 0.2-0.5 parts UV absorber, and 2-4 parts flow pattern masterbatch. The core material is extruded using a 65 / 132 conical twin-screw extruder, and the surface material is extruded using a 45 / 100 conical twin-screw extruder or a φ45 single-screw extruder as a co-extruder. The core and surface materials are then combined and molded using a co-extrusion die, with a co-extrusion layer thickness of 1~1.5mm. The temperature settings for the 65 / 132 conical twin-screw extruder are as follows: Zone 1 185~195℃, Zone 2 170~190℃, Zone 3 125~150℃, Zone 4 125~150℃, and the confluence core 120~140℃. The temperature settings for the 45 / 100 conical twin-screw extruder are: Zone 1 180~200℃, Zone 2 175~190℃, Zone 3 165~180℃, and Zone 4 165~180℃. The φ45 single-screw extruder is equipped with a drying hopper. The temperature settings of the φ45 single-screw extruder are: Zone 1 155~170℃, Zone 2 165~180℃, Zone 3 175~190℃, and Zone 4 180~190℃.

2. The method for preparing wood-plastic co-extruded wood-plastic textured co-extruded profiles according to claim 1, characterized in that, The wood flour or reed flour is 80-100 mesh with a moisture content of less than 6%; the grafting rate of maleic anhydride-grafted polyethylene is 0.8-1.2%.

3. The method for preparing wood-plastic co-extruded wood-plastic textured co-extruded profiles according to claim 1, characterized in that, The lubricant is one or more of stearic acid, stearate, butyl stearate, oleamide, ethylene bis-stearamide, or polyethylene wax / stearic acid composite lubricant; the colorant is one or more of iron oxide red, iron oxide yellow, iron oxide black, or carbon black.

4. The method for preparing wood-plastic co-extruded wood-plastic textured co-extruded profiles according to claim 1, characterized in that, The antioxidant is antioxidant 168 or antioxidant 1010; the ultraviolet additive is at least one of light stabilizer 744, light stabilizer GW-540, light stabilizer AM-101, ultraviolet absorber UV-531, and ultraviolet absorber UV-9.

5. The method for preparing wood-plastic co-extruded wood-plastic textured co-extruded profiles according to claim 1, characterized in that, The flow pattern masterbatch is a mixture of PP resin, PE resin, color powder and functional additives. By mass, it consists of 20-45 parts PP resin, 30-60 parts PE resin, 15-50 parts color powder and 0-6 parts functional additives. The color powder is one or more of iron oxide red, iron oxide yellow, iron oxide black or carbon black. The functional additives include antioxidants and UV additives.

6. The method for preparing wood-plastic co-extruded wood-plastic textured co-extruded profiles according to claim 1, characterized in that, The 65 / 132 conical twin-screw extruder has a screw speed of 0~40 r / min and a main motor power of 37 kW; the 45 / 100 conical twin-screw extruder has a screw speed of 0~45 r / min and a main motor power of 15 kW; the φ45 single-screw extruder has a screw speed of 0~60 r / min and a main motor power of 11 kW.

7. The method for preparing wood-plastic co-extruded wood-plastic textured co-extruded profiles according to claim 1, characterized in that, The 65 / 132 conical twin-screw extruder and the 45 / 100 conical twin-screw extruder are equipped with a φ25 single-screw extruder at the feed port for feeding lubricant; the 45 / 100 conical twin-screw extruder is equipped with a φ20 single-screw side feeder and an agricultural seeder at the feed port for feeding flow pattern masterbatch.

8. The method for preparing wood-plastic co-extruded wood-plastic textured co-extruded profiles according to claim 1, characterized in that, The 65 / 132 conical twin-screw extruder is equipped with a φ25 single-screw extruder at the feed port for feeding lubricant; after the lubricant, flow pattern masterbatch and surface material are mixed, they are fed into the φ45 single-screw extruder in one go.

9. The method for preparing wood-plastic co-extruded wood-plastic textured co-extruded profiles according to claim 1, characterized in that, The core extrusion speed is 0.5~1.2m / min, the surface co-extrusion speed is 0.6~1.5m / min, and the traction speed is 0.5~1.3m / min.

10. A wood-plastic co-extruded wood-plastic textured co-extruded profile prepared by the method described in any one of claims 1-9, characterized in that, The profile has a random striped texture, a peel strength of not less than 3.5MPa, a flexural strength of not less than 25MPa, a water absorption rate of less than 1.5%, and a surface electrostatic voltage of ≤3kV; after 3000 hours of artificial accelerated aging, there is no significant change in appearance, and the mechanical properties retain more than 90%.

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