A method and system for recycling waste plastics

Abstract

The application discloses a kind of waste plastics recycling processing method and system, belong to environmental protection technical field, solve the mechanical blending recycling technology of existing waste plastics, and many defects are caused to system due to containing different categories of incompatible plastics, reduce the service performance of the problem of workpiece, the system includes: mixed module: for mixing waste plastics, the module of getting blend material;Hot pressing module: for the module that blend material is pressed into board material by heating mould;Cutting module: for the module that the board material is cut into several rectangular blocks;Stretching module: for the module that the several rectangular blocks are stretched into recyclable material.The application is applicable to the recycling processing and reusing scene of waste plastics.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology, and specifically relates to a method for recycling waste plastics. Background Technology

[0002] Since their invention, polymer materials have rapidly penetrated various industries due to their low price, superior processing performance, and outstanding comprehensive application properties. While the widespread use of plastic products has brought convenience to human life, it has also led to a daily increase in waste plastics.

[0003] Existing methods for recycling waste plastics include mechanical recycling, gasification decomposition to obtain fuel for heating and power generation, and thermal cracking to refine oil.

[0004] Mechanical recycling methods require relatively pure raw materials and the addition of numerous additives to improve the performance of the finished products. Furthermore, the meticulous sorting and classification of waste plastics is a costly and expensive process, making conventional mechanical recycling uneconomical. Gasification and pyrolysis methods also face the problems of high cost and low yield.

[0005] Currently, most waste plastics on the market are polyethylene and polypropylene products, and these two materials are incompatible. Since most recycled plastics are not sorted, directly processing mixtures of different types of plastics using existing processes will result in the final product being prone to breakage and poor mechanical properties due to easy interface separation caused by the incompatibility of different components. Therefore, there is an urgent need in this field for a processing method that can effectively improve the mechanical properties of polymer products while suppressing the development of internal micropore defects.

[0006] Solid-state stretching is a solid-state processing method for polymer materials. Simply put, it is a processing technology that stretches materials from a mold in a solid state to adjust the microstructure and properties of the materials.

[0007] Die-drawing technology is widely used in automobile manufacturing, furniture production, textile manufacturing, and other production fields. Compared with extrusion, which also uses molds, this technology does not require heating materials to a molten state, thus saving a significant amount of energy. Its development is still in its infancy. Therefore, we will research and develop new methods for processing waste plastics using die-drawing technology, thereby opening up new avenues for global waste plastic processing technology and related products, accelerating the consumption of waste plastics, reducing pollution, and promoting the recovery of a healthy global environment. Summary of the Invention

[0008] This invention addresses the problem that existing mechanical blending recycling technologies for waste plastics often result in numerous defects in the recycled parts due to the presence of incompatible plastics of different types, thus reducing the performance of the parts. The invention proposes a novel processing method for preparing waste plastic parts based on solid-state die-drawing technology.

[0009] A waste plastic recycling and processing system includes:

[0010] Mixing module: A module used to mix waste plastics to obtain blends;

[0011] Hot pressing module: a module used to press the blended material into a sheet using a heated mold;

[0012] Cutting module: A module used to cut the sheet material into several rectangular blocks;

[0013] Stretching module: A module used to stretch the plurality of rectangular blocks into recyclable material.

[0014] Furthermore, the waste plastics include: waste polyethylene and polypropylene;

[0015] Furthermore, the mixing of waste plastics refers to mixing the waste polyethylene and polypropylene in any proportion;

[0016] Furthermore, the method involves adding nano-inorganic calcium carbonate and other particles to the waste plastic mixture to enhance its compatibilization.

[0017] Furthermore, the mixing module includes a front-mounted cavity for mixing the waste plastic;

[0018] Furthermore, the heating mold is located behind the front placement cavity and is used to heat and press the blend material;

[0019] Furthermore, the stretching module includes a clamp located at the discharge port of the heating mold for stretching the plurality of rectangular blocks;

[0020] Furthermore, the thickness of the plate is 5mm, the width is 5mm, and the length is 13cm;

[0021] Furthermore, the stretching temperature range for stretching the plurality of rectangular blocks using a fixture is from room temperature to the melting point of the waste plastic.

[0022] The present invention also provides a method for recycling and processing waste plastics, comprising:

[0023] Mixing step: The step used to mix waste plastics to obtain a blend;

[0024] Hot pressing step: a step used to press the blend into several rectangular blocks using a heated mold;

[0025] Stretching step: A step used to stretch the plurality of rectangular blocks into recyclable material.

[0026] The beneficial effects of this invention are:

[0027] Existing technologies for recycling waste plastics mainly rely on mechanical recycling, gasification and decomposition to obtain fuel for heating and power generation, and pyrolysis for refining. However, the recycled parts often contain incompatible plastics, leading to numerous defects and reduced performance. The solid-state molding process proposed in this invention is a technique that balances tension and compression. During molding, the material spontaneously forms necks, creating an oriented structure that enhances the mechanical properties of the parts.

[0028] The waste plastic recycling and processing method proposed in this invention is mainly aimed at products made from the two most widely used types of plastics in the world, namely polyethylene (PE) and polypropylene (PP) products. This invention is used for their mixed recycling and processing.

[0029] By using nano-inorganic calcium carbonate and other particles to compatibilize waste polyethylene and polypropylene systems, the process of sorting and recycling waste polyethylene and polypropylene materials is eliminated. Furthermore, solid-state molding technology is used to suppress the generation of material defects and overcome the disadvantage of easy breakage when the material is freely stretched, so as to prepare high-performance and diversified waste plastic products.

[0030] The solid-state molding technique proposed in this invention can effectively suppress the nucleation and expansion of micropores inside polymer materials.

[0031] The method proposed in this invention does not require adjusting the mixing ratio of waste plastics; waste plastics of any ratio can be recycled and processed using this invention.

[0032] This invention is applicable to the recycling, processing, and reuse of waste plastics. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the solid-state die stretching technology described in Embodiment 3, where 1 is a hot-pressing die, 2 is a clamp, and 3 is the stretching direction;

[0034] Figure 2 Photographs of the polypropylene and polyethylene blend (5:5) described in Embodiment 6 after solid molding and free stretching at 70°C;

[0035] Figure 3 The tensile stroke and tensile force curves of the polypropylene and polyethylene blend (5:5) described in Embodiment 6 under solid molding and free stretching at 70°C are shown. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] Implementation Method 1:

[0038] The waste plastic recycling and processing system described in this embodiment includes:

[0039] Mixing module: A module used to mix waste plastics to obtain blends;

[0040] Hot pressing module: a module used to press the blended material into a sheet using a heated mold;

[0041] Cutting module: A module used to cut the sheet material into several rectangular blocks;

[0042] Stretching module: A module used to stretch the plurality of rectangular blocks into recyclable material.

[0043] Specifically:

[0044] The waste plastics described in this embodiment include products made from waste polyethylene (PE) and waste polypropylene (PP).

[0045] The mixing of waste plastics described in this embodiment refers to mixing the waste polyethylene and polypropylene in any proportion.

[0046] The plate described in this embodiment has a thickness of 5mm, a width of 5mm, and a length of 13cm, and the rectangular blocks are different rectangular strips.

[0047] The board material described in this embodiment can also be a board material with a thickness * width * length of 10cm * 10cm * 30cm.

[0048] This embodiment proposes a waste plastic recycling and processing system based on solid-state molding technology. Solid-state molding is a processing technique that combines stretching and compression. During molding, the material spontaneously forms necks, and this necking process creates an oriented structure, improving the mechanical properties of the finished part. Furthermore, the waste plastic recycling and processing system proposed in this embodiment eliminates the need for special adjustment of the ratio of polypropylene and polyethylene products when mixing the waste plastics, making the process convenient and simple. It also eliminates the need for further sorting of polyethylene and polypropylene during waste sorting.

[0049] Implementation Method Two:

[0050] This embodiment is a further example illustrating the mixing of waste plastics in a waste plastic recycling and processing system described in Embodiment 1.

[0051] The method described in this embodiment involves adding nano-inorganic calcium carbonate and other particles to the waste plastic mixture to enhance compatibilization. Alternatively, polyethylene and polypropylene can be blended separately.

[0052] By using nano-inorganic calcium carbonate and other particles to compatibilize waste polyethylene and polypropylene systems, the process of sorting and recycling waste polyethylene and polypropylene materials is eliminated. Furthermore, solid-state molding technology is used to suppress the generation of material defects and overcome the disadvantage of easy breakage when the material is freely stretched, so as to prepare high-performance and diversified waste plastic products.

[0053] Implementation Method 3:

[0054] Reference Figure 1 This implementation method is described below.

[0055] This embodiment is a further illustrative example of a waste plastic recycling and processing system described in Embodiment 1.

[0056] The mixing module of the waste plastic recycling and processing system described in this embodiment includes a pre-positioning chamber for mixing the waste plastic to obtain the blend.

[0057] The heating mold is located at the rear outlet of the front placement cavity and is used to heat and press the blended material, which is then cut to obtain the several rectangular blocks.

[0058] The stretching module includes a clamp located at the discharge port of the heating mold, used to stretch the plurality of rectangular blocks in the direction of stretching along the discharge direction of the hot pressing mold.

[0059] Implementation Method Four:

[0060] This embodiment is a further example illustrating the stretching of the plurality of rectangular blocks using a clamp in a waste plastic recycling and processing system described in Embodiment 1.

[0061] In this embodiment, the stretching temperature range for stretching the plurality of rectangular blocks using a fixture is from room temperature to the melting point of the waste plastic.

[0062] Specifically:

[0063] The ambient temperature described in this embodiment is 25°C. The melting point of the waste plastic is the maximum melting point of the polyethylene material and the polypropylene material, that is: the maximum melting point of the polyethylene material is 110°C and the maximum melting point of the polypropylene material is 170°C.

[0064] The temperature range described in this embodiment is 25°C to 170°C.

[0065] Implementation Method 5:

[0066] The waste plastic recycling and processing method described in this embodiment includes:

[0067] Mixing step: The step used to mix waste plastics to obtain a blend;

[0068] Hot pressing step: a step used to press the blend into a sheet material using a heated mold;

[0069] Cutting step: A step used to cut the sheet material into several rectangular blocks;

[0070] Stretching step: A step used to stretch the plurality of rectangular blocks to obtain recyclable material.

[0071] Implementation Method Six:

[0072] Reference Figure 2 , Figure 3 This implementation method is described below.

[0073] This embodiment compares the processing effect of solid-state molding technology on blended polyethylene and polypropylene by freely stretching solid-state molded fish.

[0074] See macro photos Figure 2 , Figure 2 In the middle, the upper part is the sample processed by solid-state die stretching technology, and the lower part is the sample processed by free stretching. It can be seen that the sample processed by solid-state die stretching can be continuously stretched without breaking, but the sample processed by free stretching breaks randomly in the early stage of stretching.

[0075] For specific tensile curves, see [link / details]. Figure 3 Solid-state molding can successfully process polyethylene and polypropylene blends, overcoming the drawback of easy breakage during free stretching.

[0076] Therefore, solid-state molding technology can serve as a new method for the recycling and processing of waste polyethylene and polypropylene plastics in different proportions.

Claims

1. A waste plastic recycling and processing system, characterized in that, The system includes: Mixing module: A module used to mix waste plastics to obtain blends; Hot pressing module: a module used to press the blended material into a sheet using a heated mold; Cutting module: A module used to cut the sheet material into several rectangular blocks; Stretching module: A module used to stretch the plurality of rectangular blocks to obtain recyclable materials; The materials of the waste plastics include: waste polyethylene and polypropylene; The mixing of waste plastics involves mixing waste polyethylene and polypropylene in any proportion, and adding a particle compatibilizing blending system of nano-inorganic calcium carbonate during the mixing of waste plastics. The mixing module includes a front-mounted chamber for mixing the waste plastic; The heating mold is located on one side of the discharge port of the front cavity. The mixed material flowing out of the discharge port of the front cavity enters the heating mold for heating and pressing. The stretching module includes a clamp, which is located at the discharge port of the heating mold and is used to stretch the plurality of rectangular blocks using a mold for solid-state stretching processing. The stretching temperature range for stretching the rectangular blocks using a fixture is from room temperature to the melting point of the waste plastic.

2. The waste plastic recycling and processing system according to claim 1, characterized in that, The plate has a thickness of 5mm, a width of 5mm, and a length of 13cm.

3. A method for recycling and processing waste plastics, characterized in that, The method using a waste plastic recycling and processing system as described in any one of claims 1-2 includes: Mixing step: The step used to mix waste plastics to obtain a blend; Hot pressing step: a step used to press the blend into a sheet material using a heated mold; Cutting step: A step used to cut the sheet material into several rectangular blocks; Stretching step: A step used to stretch the plurality of rectangular blocks to obtain recyclable material; The materials of the waste plastics include: waste polyethylene and polypropylene; The mixing of waste plastics refers to mixing the waste polyethylene and polypropylene in any proportion; The mixing module includes a front-mounted chamber for mixing the waste plastic; The heating mold is located on one side of the discharge port of the front cavity. The mixed material flowing out of the discharge port of the front cavity enters the heating mold for heating and pressing. The stretching module includes a clamp, which is located at the discharge port of the heating mold and is used to stretch the plurality of rectangular blocks; The stretching temperature range for stretching the rectangular blocks using a fixture is from room temperature to the melting point of the waste plastic.

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