Injection-molding-grade high-corrosion-resistance wood-plastic composite material and preparation method thereof

Abstract

The invention relates to the technical field of wood-plastic composite materials, and particularly discloses an injection molding grade high-corrosion-resistance wood-plastic composite material and a preparation method thereof.The injection molding grade high-corrosion-resistance wood-plastic composite material is prepared from, by weight, 43-75 parts of waste plastic, 10-25 parts of wood flour, 12-18 parts of pitaya peel particles, 3-7 parts of talcum powder and 4-6 parts of light calcium carbonate powder. 5-9 parts of chitosan, 2-8 parts of a coupling agent, 3-5 parts of an adhesive and 1-2 parts of an antioxidant. The injection molding grade wood-plastic composite material with high corrosion resistance, which has the characteristics of excellent injection molding property, high rigidity, high corrosion resistance, mechanical property and the like, is developed by modifying two mixed fillers, namely the pitaya peel particles and the wood flour, with a specific chitosan surface accelerant and mixing with a waste plastic matrix.

Description

Technical Field

[0001] This invention relates to the field of wood-plastic composite materials technology, and in particular to an injection-molded grade high corrosion-resistant wood-plastic composite material and its preparation method. Background Technology

[0002] The recycling of waste plastics has a broad market potential for green and environmentally friendly materials, and also provides an economical and feasible solution to the problem of white pollution. Currently, the market development focus is on wood-plastic composites and building materials, with wood-plastic composites having been extensively studied.

[0003] Wood-plastic composites (WPCs) are high-performance composite materials made by mixing waste wood, crop straw, and other plant fibers with plastics, adding additives, and processing them through hot pressing, extrusion, and injection molding. WPCs not only possess the unique woody feel of natural wood but also exhibit excellent mechanical properties, dimensional stability, water resistance, abrasion resistance, chemical corrosion resistance, insect resistance, ease of coloring, low maintenance requirements, long service life, ease of molding, and secondary processing capabilities. They can replace natural wood and solve the environmental problem of where waste plastics cannot be disposed of, thus attracting increasing attention. The processing, molding, and interface modification technologies of WPCs are core technologies related to their performance and applications, and are a hot research topic.

[0004] Currently, most wood-plastic composite materials on the market are made from waste wood, sawdust, wood branches, rice husks, crop straw, peanut shells, and sisal fibers, mixed with raw materials or recycled materials such as polypropylene, polyethylene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, and polystyrene in a certain proportion, with the addition of special processing aids. To improve the strength of wood-plastic composites, a large amount of wood flour is often added as a filler. However, the aforementioned plant fiber wood raw materials themselves have poor flowability. While they can improve the strength of waste plastics when used as fillers, processing and molding are difficult, and it is hard to ensure the uniformity of the raw materials during processing. The molding process is difficult to control, and they cannot be used as injection-molded products; only relatively simple products can be extruded, which greatly limits the application range of wood-plastic composites. Reducing the amount of wood flour to ensure flowability leads to a decrease in the strength of wood-plastic composites. How to improve the selection of raw materials to prevent a decrease in the strength of wood-plastic composites is an urgent problem to be solved. Summary of the Invention

[0005] Based on this, the purpose of this invention is to provide an injection-molded high corrosion-resistant wood-plastic composite material and its preparation method. This injection-molded high corrosion-resistant wood-plastic composite material can not only be injection molded, but also has excellent strength and strong corrosion resistance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an injection-molded, highly corrosion-resistant wood-plastic composite material, which is prepared from the following components in parts by weight: 43-75 parts waste plastic, 10-25 parts wood flour, 12-18 parts dragon fruit peel granules, 3-7 parts talc, 4-6 parts light calcium carbonate powder, 5-9 parts chitosan, 2-8 parts coupling agent, 3-5 parts adhesive, and 1-2 parts antioxidant.

[0007] As a further improvement to the above-mentioned solution of the present invention, the method for preparing the dragon fruit peel granules is as follows: clean the dragon fruit peel, cut it into pieces, dry it until the moisture content is below 5%, crush it, and sieve it to obtain dragon fruit peel granules.

[0008] As a further improvement to the above-described scheme of the present invention, the coupling agent is at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

[0009] As a further improvement to the above-described solution of the present invention, the adhesive is at least one of unsaturated polyester resin, epoxy resin, phenolic resin, amino resin, hydroxymethyl resorcinol, and vinyl resin.

[0010] As a further improvement to the above-mentioned solution of the present invention, the antioxidant is at least one of phosphite antioxidants, thioether antioxidants, thioester antioxidants, and amine antioxidants.

[0011] As a further improvement to the above-mentioned solution of the present invention, the light calcium powder is at least one of spindle-shaped calcium, cubic calcium, needle-shaped calcium, and spherical chain-shaped calcium; the talc powder has a mesh size of 500 to 5000 mesh.

[0012] As a further improvement to the above-mentioned solution of the present invention, the wood powder is at least one of coniferous wood powder, broadleaf wood powder, bamboo powder, fruit wood powder, and recycled mixed wood powder.

[0013] As a further improvement of the above-mentioned solution of the present invention, the injection-molded high corrosion-resistant wood-plastic composite material further includes the following components in parts by weight: the waste plastic is waste PVC, waste PE, waste PP or waste ABS.

[0014] This invention also provides a method for preparing the injection-molded, highly corrosion-resistant wood-plastic composite material as described above, comprising the following steps: S1. Add dragon fruit peel granules and wood flour to a high-speed mixer and mix for 10-15 minutes. Then add chitosan and continue stirring for 5-10 minutes to obtain a premix. S2. Waste plastics, talc powder, light calcium carbonate powder, coupling agent, adhesive and antioxidant are added to the premix in proportion and mixed. The mixture is then melt-blended, extruded and granulated using a twin-screw extruder to obtain injection-grade high corrosion-resistant wood-plastic composite material.

[0015] As a further improvement of the above-mentioned solution of the present invention, in step S1, before mixing, the wood powder is passed through an airflow dryer (inlet 200°C, outlet 80°C), and then an online moisture meter is used to monitor the moisture content of the wood powder in real time to ensure it is below 2%. Then, it is transferred to a sealed cooler to cool to below 30°C, and finally immediately transferred to a sealed package. Before leaving the factory, an oven method (baking at 103±2°C for 2-5 hours) is used to ensure that the moisture content is consistently below 2%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The inventors of this invention unexpectedly discovered that using dragon fruit peel particles as a filler in the preparation of wood-plastic composites can significantly improve the strength of wood-plastic composites, ensuring strength while reducing the amount of wood flour used. Dragon fruit peel is rich in fiber, containing a significant amount of coarse fiber, anthocyanins, red pigments, pectin, flavonoids, and other components. These components have good film-forming properties, resulting in films with good folding endurance and strong barrier properties. To facilitate the mixing of dragon fruit peel particles with wood flour and the plastic matrix, this invention adds a certain amount of chitosan to the raw materials. The main function of chitosan is as a high-quality pretreatment agent and interfacial compatibility promoter for biomass fillers. It pre-coats and activates the filler surface through physical adsorption and hydrogen bonding, creating optimal conditions for subsequent bonding with coupling agents and the plastic matrix, thereby significantly improving the mechanical properties, water resistance, and overall compatibility of the composite material. This invention develops an injection-grade, highly corrosion-resistant wood-plastic composite material by modifying dragon fruit peel particles with a specific chitosan surface accelerator and mixing them with waste plastic matrix. This composite material exhibits excellent injection molding properties, high rigidity, high corrosion resistance, and mechanical properties.

[0017] In this invention, the proportion of wood flour in the waste plastic matrix is ​​relatively small, which greatly improves the problem of poor processing fluidity of existing wood-plastic composite materials. The resulting wood-plastic composite material has good injection molding properties and is an injection-grade wood-plastic material that can be produced through a simple injection molding process. It can become a rare injection-grade wood-plastic material product in the current market, and its application fields are greatly broadened.

[0018] To increase lubricity, this invention also selects talc powder; in addition, light calcium carbonate powder has the characteristics of regular particle shape, narrow particle size distribution and small particle size, which can increase product volume, improve processing performance, improve dimensional stability and improve physical properties. The addition of light calcium carbonate powder ensures the processing performance of raw materials and improves dimensional stability.

[0019] This invention uses two mixed fillers, dragon fruit peel granules and wood flour, which, when mixed with waste plastic matrix, enhance the performance of wood-plastic composite materials. Dragon fruit peel granules themselves are rich in strong antibacterial substances, and together with chitosan, they can resist mold corrosion. They can withstand acidic environments with pH=3.5 and alkaline environments with pH=8.5, with corrosion rates of only 6.0% and 5.5% respectively in these two environments, demonstrating strong corrosion resistance. Furthermore, they can resist mold corrosion well without the need for added antibacterial agents, resulting in a long service life. Detailed Implementation

[0020] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Specific information on the raw materials used in the following embodiments and comparative examples is as follows: Wood powder: 60-mesh bamboo powder Mingzhu, manufactured by Lin'an Mingzhu Bamboo and Wood Powder Co., Ltd. Talc powder: 1250 talc powder, grade 90-20-A, manufactured by Guangxi Longsheng Huamei Talc Development Co., Ltd.; Light calcium carbonate powder: cubic calcium, brand name KS-700, manufactured by Keynes Nanomaterials Co., Ltd. Coupling agent: silane coupling agent, brand name KH-550, manufactured by Hangzhou Yiyuan Chemical Co., Ltd.; Adhesive: Vinyl resin, grade SH-5202P, manufactured by Hubei Longsheng Sihai New Materials; The antioxidant is a compound of phosphite antioxidants and amine antioxidants in a mass ratio of 1:1.

[0021] The above-mentioned raw materials are only for illustrating the source and composition of the reagents used in the experiments of this invention, so as to fully disclose them, and do not imply that the invention cannot be achieved by using other similar reagents or reagents provided by other suppliers.

[0022] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0023] A method for preparing an injection-molded, highly corrosion-resistant wood-plastic composite material includes the following steps: S1. Wash and cut fresh dragon fruit peel into pieces, dry until the moisture content is below 5%, and crush into dragon fruit peel granules (20 mesh); pass the wood flour through an airflow dryer (inlet 200℃, outlet 80℃), then use an online moisture meter to monitor the moisture content of the wood flour in real time to ensure it is below 2%, then transfer it to a sealed cooler to cool to below 30℃, and finally immediately transfer it to a sealed package in a moisture-proof storage room. Before use, bake it in an oven at 103±2℃ for 2-5 hours to ensure the moisture content is consistently below 2%; S2. Add dragon fruit peel granules (moisture content below 5%) and wood flour (moisture content consistently below 2%) to a high-speed mixer and stir for 10 minutes. Then add chitosan in proportion and continue stirring for 5 minutes to obtain a premix. S3. Add waste plastic, talc powder, light calcium carbonate powder, coupling agent, adhesive and antioxidant to the premix in proportion, mix and then melt blend, extrude and granulate at 180°C using a twin-screw extruder to obtain injection molding grade high corrosion resistant wood-plastic composite material.

[0024] Examples 1-7 are shown in Table 1, and the component formulations of Comparative Examples 1-8 are shown in Table 2.

[0025] Table 1. Component formulations of Examples 1-7

[0026] Table 2. Component formulations of Comparative Examples 1-8

[0027] Test case The wood-plastic composite materials prepared in the above examples and comparative examples were injection molded in an injection molding machine under the same conditions according to the standard. The injection conditions were: injection temperature 188℃, injection pressure 11MPa, injection speed 50g / s, and cooling and curing time 25s. The injection molded samples were subjected to performance tests: tensile strength test (conducted on a plastic tensile testing machine according to GB1040-79), and corrosion resistance test under different conditions (the test items and methods refer to patent CN 105131634 A). The product performance test results are shown in Table 3.

[0028] Table 3 Performance test results of injection molded samples

[0029] The results in Table 3 show that: The wood-plastic composite materials prepared in the various embodiments of the present invention exhibit excellent injection molding properties, high rigidity, high corrosion resistance, and mechanical properties, thus expanding the market application value of injection-molded wood-plastic composite materials.

[0030] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0031] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A wood-plastic composite material with high corrosion resistance for injection molding, characterized in that, It is prepared from the following components in parts by weight: 43-75 parts waste plastic, 10-25 parts wood flour, 12-18 parts dragon fruit peel granules, 3-7 parts talc, 4-6 parts light calcium carbonate powder, 5-9 parts chitosan, 2-8 parts coupling agent, 3-5 parts adhesive and 1-2 parts antioxidant.

2. The injection-molded, high-corrosion-resistant wood-plastic composite material according to claim 1, characterized in that, The method for preparing the dragon fruit peel granules is as follows: clean the dragon fruit peel, cut it into pieces, dry it until the moisture content is below 5%, crush it, and sieve it to obtain dragon fruit peel granules.

3. The injection-molded, high-corrosion-resistant wood-plastic composite material according to claim 1, characterized in that, The coupling agent is at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

4. The injection-molded, high-corrosion-resistant wood-plastic composite material according to claim 1, characterized in that, The adhesive is at least one of unsaturated polyester resin, epoxy resin, phenolic resin, amino resin, hydroxymethyl resorcinol, and vinyl resin.

5. The injection-molded, high-corrosion-resistant wood-plastic composite material according to claim 1, characterized in that, The antioxidant is at least one of phosphite antioxidants, thioether antioxidants, thioester antioxidants, and amine antioxidants.

6. The injection-molded, high-corrosion-resistant wood-plastic composite material according to claim 1, characterized in that, The light calcium carbonate powder is at least one of spindle-shaped calcium carbonate, cubic calcium carbonate, needle-shaped calcium carbonate, and spherical chain-shaped calcium carbonate; the talc powder has a mesh size of 500-5000 mesh.

7. The injection-molded, high-corrosion-resistant wood-plastic composite material according to claim 1, characterized in that, The wood flour is at least one of coniferous wood flour, broadleaf wood flour, bamboo flour, fruitwood flour, and recycled mixed wood flour.

8. The injection-molded, high-corrosion-resistant wood-plastic composite material according to claim 1, characterized in that, The waste plastics are waste PVC, waste PE, waste PP or waste ABS.

9. A method for preparing an injection-molded, highly corrosion-resistant wood-plastic composite material as described in any one of claims 1-8, characterized in that, It includes the following steps: S1. Add dragon fruit peel granules and wood flour to a high-speed mixer and mix for 10-15 minutes. Then add chitosan and continue stirring for 5-10 minutes to obtain a premix. S2. Waste plastics, talc powder, light calcium carbonate powder, coupling agent, adhesive and antioxidant are added to the premix in proportion and mixed. The mixture is then melt-blended, extruded and granulated using a twin-screw extruder to obtain injection-molded high corrosion-resistant wood-plastic composite material.

10. The method for preparing injection-molded high corrosion-resistant wood-plastic composite material according to claim 9, characterized in that, In step S1, before mixing, the wood flour is passed through an airflow dryer, and then an online moisture meter is used to monitor the moisture content of the wood flour to be below 2%. Then it is transferred to a sealed cooler to be cooled to below 30°C. Finally, it is immediately transferred to a sealed package in a moisture-proof storage room. Before use, it is baked in an oven at 103±2°C for 2-5 hours to ensure that the moisture content is stably below 2%.

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