High-toughness waste plastic and wood fiber composite material and preparation method thereof

Abstract

The invention discloses a high-toughness waste plastic and wood fiber composite material and a preparation method thereof, and relates to the technical field of environmental protection. The preparation method comprises the following steps: carrying out sorting pretreatment on the municipal solid waste, and carrying out pretreatment such as crushing, cleaning, drying, grinding and granulating on the screened film plastic and hard plastic; the waste wood material is subjected to grinding and drying pretreatment, and wood powder is prepared; putting the pretreated waste plastics, wood fibers and other auxiliaries into a high-speed mixer for mixing; granulating the uniformly mixed material subjected to high-speed mixing by using a granulating machine; and extruding the granules through an exhaust type double-screw extruder, and carrying out air cooling and sizing to obtain the high-performance composite material profile. The preparation method disclosed by the invention is environment-friendly, simple, economical, low in investment, low in operation cost, high in comprehensive utilization rate and recycling degree, basically free from secondary pollution and obvious in environmental and social benefits, and opens up a new way for recycling urban garbage.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technology, in particular to the field of solid waste resource utilization technology, and specifically to a method for preparing high-performance composite profiles using mixed waste plastics and waste wood materials in urban domestic waste as raw materials. Background Art

[0002] In the fields of resource recycling and environmentally friendly material development, the reuse of waste plastics and wood fiber has long been a research hotspot. Traditional methods for disposing of waste plastics, mostly through landfill or incineration, not only consume significant land resources but also produce hazardous substances like dioxins during the incineration process, causing environmental pollution. Furthermore, waste wood materials, if not properly utilized, also result in a waste of resources. Traditional wood-plastic composites, which primarily utilize a single type of plastic and fresh wood fiber, underutilize resources, resulting in high costs and limited environmental benefits.

[0003] While some existing patents focus on the reprocessing of waste plastics and wood fibers, they fall short in improving material properties and optimizing production processes. Some patents employ a single approach to pre-processing waste plastics and wood fibers, resulting in suboptimal composite material performance. Others generate significant amounts of waste during the production process, leading to low resource utilization. Summary of the Invention

[0004] The present invention aims to provide a high-toughness waste plastic / wood fiber composite material and a preparation method thereof. The method is environmentally friendly, simple, and economical, with low investment, low operating costs, high comprehensive utilization rate and resource recovery, and substantially no secondary pollution. The method has significant environmental and social benefits and opens up a new path for the resource recovery of urban waste. The method comprises the following specific steps:

[0005] S1. Separate film plastics and hard plastic products from municipal solid waste and perform crushing and drying pretreatment;

[0006] S2, grinding and drying the waste wood materials to prepare wood powder;

[0007] S3, placing the pretreated plastic, wood material and additives in a high-speed mixer for mixing;

[0008] S4, granulating the uniform mixture after high mixing using a granulator;

[0009] S5. The pellets are extruded through a venting twin-screw extruder, air-cooled and sized to obtain high-performance composite material profiles.

[0010] Furthermore, the film plastic in step S1 is low-density polyethylene, and the hard plastic is polypropylene.

[0011] Furthermore, in step S1, the crushing and drying pretreatment is: sending the sorted film plastics and hard plastic products into a special plastic crusher for crushing, and mechanically cleaning and drying the crushed plastics.

[0012] Furthermore, step S1 further includes: grinding the crushed and dried hard plastic to 100 mesh using a high-speed vortex grinder, and granulating the crushed and dried film plastic using a plastic recycling granulator.

[0013] Furthermore, the wood material in step S2 includes sawdust, miscellaneous wood powder, bamboo powder, rice husks, peanut shells, rice bran and straw.

[0014] Furthermore, in step S2, the grinding is to grind the wood material into wood powder with a particle size of more than 20 meshes using a wood grinder, and the wood powder can be dried by simply drying it naturally in sunlight.

[0015] Furthermore, the adding method in step S3 is automatic metering feeding, and the additives include compatibilizers and plasticizers. The pretreated plastic, wood material, compatibilizer, and plasticizer are added first, and then other additives are added; the wood material is added twice, the first time in the feeding hopper and the second time at the middle side feeding port.

[0016] Furthermore, step S4 is: the granulator is equipped with a fast electric filter changing device and automatic temperature control, and the pelletizer adopts a speed regulating motor and a discharge speed of the extruder to synchronize the pelletizing.

[0017] Furthermore, step S5 is: feeding the cut particles into a vented, counter-rotating twin-screw extruder, using heating and screw shearing action to convert the plastic into a melt, and directly preparing a continuous profile by molding under pressure.

[0018] The present invention has achieved the following beneficial effects:

[0019] 1. The present invention significantly improves resource utilization. It effectively utilizes waste mixed plastics and various waste wood materials in municipal solid waste, while recycling waste generated during the production process. This greatly improves resource utilization, has good social and environmental benefits, and is in line with the concept of sustainable development.

[0020] 2. The composite profiles prepared by the present invention have excellent performance. Through scientific raw material pretreatment and mixing methods, the final composite material has high toughness, which broadens its application range in the fields of construction, packaging, etc.

[0021] 3. This invention further optimizes the existing production process. In the granulation and extrusion stages, it is equipped with a fast electric filter-changing device, a speed-regulating motor, and other equipment, achieving automation and precision in the production process, improving production efficiency and ensuring the stability of product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a process flow chart for preparing high-performance composite profiles according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below. All features disclosed in this specification, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any manner. Specific embodiments

[0025] A method for preparing a high-toughness waste plastic and wood fiber composite material comprises the following steps:

[0026] S1. Waste samples were collected from a municipal waste treatment plant in southern China. A multi-stage sorting process was used to separate film plastics (such as low-density polyethylene (LDPE)) and rigid plastics (such as polypropylene (PP)) from the municipal waste. The separated LDPE and PP were crushed in a specialized plastic crusher. The crushed waste plastics were then soaked in a hot alkaline solution for a period of time before being transferred to a water tank equipped with a mechanical agitator. This mechanical agitator further removed loose dirt, such as sand and soil, adhering to the plastic surface, allowing it to sink to the bottom of the tank. The cleaned, crushed waste plastics were then centrifuged and dried in an airflow dryer. Finally, the cleaned and dried rigid plastics were ground to 100 mesh using a high-speed vortex mill, while the film flakes were granulated using a plastic recycling granulator.

[0027] S2. Sawdust is selected as waste wood material, and is made into wood powder with a particle size of 20 mesh using a wood powder machine, and is naturally dried in sunlight.

[0028] S3. Place the rigid plastic abrasive, film flake particles, wood flour, compatibilizer (silane coupling agent), and other additives in a high-speed mixer for mixing. Automatic metering is used for addition in the following order: plastic, wood flour, compatibilizer (silane coupling agent), antioxidant (2-6-di-tert-butyl-p-cresol), and lubricant (stearic acid). The material ratios are 100:30:0.75:1.5:0.5, with a mass ratio of LDPE to PP of 5:2. The wood flour is added in two steps: the first at the hopper and the second at the center side feed port.

[0029] S4. The homogeneous mixture after high mixing is pelletized by a pelletizer. The pelletizer is equipped with a fast electric filter changing device and automatic temperature control. The pelletizer uses a speed regulating motor to synchronize the pelletizing speed with the extruder discharge speed.

[0030] S5. The cut particles are fed into a vented, counter-rotating twin-screw extruder. Heating and the shearing action of the screws convert the plastic into a melt, which is then molded under pressure to produce a continuous profile. The profile extruded from the mold is cooled and sized using dry sizing and air cooling. After sizing and cooling, a haul-off machine is installed to ensure stable and continuous production. During the product processing, some wood-plastic material waste is generated. This waste is ground in a high-speed turbo plastic grinder and then re-extruded into the twin-screw extruder along with the other components, resulting in virtually no waste throughout the entire process.

[0031] After testing, the high-toughness waste plastic / wood fiber composite material produced has excellent performance, meets the expected design requirements, and shows good applicability in actual application scenarios.

[0032] The above-described embodiments merely represent specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-toughness waste plastic and wood fiber composite material, characterized in that: The following steps are involved: S1. Separate film plastics and hard plastic products from municipal solid waste and perform crushing and drying pretreatment; S2, grinding and drying the waste wood materials to prepare wood powder; S3, placing the pretreated plastic, wood material and additives in a high-speed mixer for mixing; S4, granulating the uniform mixture after high mixing using a granulator; S5. The pellets are extruded through a venting twin-screw extruder, air-cooled and sized to obtain high-performance composite material profiles.

2. The preparation method according to claim 1, characterized in that The film plastic in step S1 is low-density polyethylene, and the hard plastic is polypropylene.

3. The preparation method according to claim 1, characterized in that In step S1, the crushing and drying pretreatment is as follows: the sorted film plastics and hard plastic products are sent to a special plastic crusher for crushing, and the crushed plastics are mechanically cleaned and dried.

4. The preparation method according to claim 1, characterized in that Step S1 also includes: grinding the crushed and dried hard plastic to 100 mesh using a high-speed vortex grinder, and granulating the crushed and dried film plastic using a plastic recycling granulator.

5. The preparation method according to claim 1, characterized in that The wood materials in step S2 include sawdust, miscellaneous wood powder, bamboo powder, rice husks, peanut shells, rice bran and straw.

6. The preparation method according to claim 1, characterized in that In step S2, the wood material is ground into wood powder with a particle size of more than 20 meshes using a wood grinder, and the wood powder can be dried by naturally drying in sunlight.

7. The preparation method according to claim 1, characterized in that The adding method in step S3 is automatic metering feeding. The additives include compatibilizers and plasticizers. The pretreated plastic, wood material, compatibilizer, and plasticizer are added first, and then other additives are added; the wood material is added twice, the first time in the feeding hopper and the second time at the middle side feeding port.

8. The preparation method according to claim 1, characterized in that Step S4 is: the granulator is equipped with a fast electric filter changing device and automatic temperature control, and the pelletizer adopts a speed regulating motor and the extruder discharge speed to synchronize the pelletizing.

9. The preparation method according to claim 1, characterized in that Step S5 is: feeding the cut particles into a venting, counter-rotating twin-screw extruder, using heating and screw shearing action to convert the plastic into a melt, and directly preparing a continuous profile through molding under pressure.

10. A composite material prepared according to the preparation method according to any one of claims 1 to 9.

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