Method for separating and recycling waste composite plastic board

Abstract

The application discloses a method for separating and recycling waste composite plastic plate materials, which comprises the following steps: removing impurities on the surface of the waste plate materials by high-pressure air blowing matrix, and removing hard impurities such as sand and metal on the surface of the plate materials; then, the material quality of the plate materials is classified and collected by using a recognition device, and the plate materials of different materials are accurately separated; the classified plate materials are washed by high-pressure spraying water to remove oil, and are dried at low temperature to remove surface oil stains and moisture; then, the interlayer adhesive layer of the plate materials is softened by using a differential low-temperature hot air activation process according to the material quality of the plate materials; the plastic base material and the film and aging adhesive layer are separated by low-speed tearing and flexible rubbing; the separated materials are subjected to gravity sedimentation and separation and intelligent air separation to remove light and heavy impurities, and pure base material fragments are obtained; the base material fragments are subjected to ultrasonic cleaning and low-temperature drying to completely remove trace adhesive residues and stains; finally, the clean base material is crushed, extruded, granulated and water-cooled to form high-quality regenerated plastic particles.

Description

Technical Field

[0001] This invention patent relates to the field of waste plastic resource recycling, specifically a method for interlayer separation and resource recycling of waste composite plastic sheets. Background Technology

[0002] PVC, PP, and PE laminated composite plastic sheets are widely used in advertising decoration, building materials, industrial protection and other fields. These sheets use rigid plastic as the base material and the surface is coated with a functional film made of polyurethane, acrylate and hot melt adhesive. The interlayer bonding strength is high and the structure is stable. There is a large amount of waste and an urgent need for recycling.

[0003] Currently, there is no complete production line for recycling waste composite plastic boards in China. The initial sorting process often relies on manual sorting to identify the type of board, which can easily lead to mixing and low subsequent stratification and purification rates. At the same time, existing waste composite plastic board recycling processes often use organic solvent dissolution and / or high-temperature pyrolysis. These processes have high reagent costs and require explosion-proof sites. Under the ring of high-temperature chemical decomposition, the plastic substrate is prone to degradation, which in turn leads to a decline in mechanical properties. In addition, the environmental protection and maintenance pressure of chemical decomposition recycling is enormous, making it difficult for small and medium-sized enterprises to implement. Summary of the Invention

[0004] The purpose of this invention is to provide a method for interlayer separation and resource recycling of waste composite plastic sheets, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, this invention provides the following technical solution: a method for interlayer separation and resource recycling of waste composite plastic sheets, comprising the following steps: S1: The sheet material is conveyed through the high-pressure air blowing matrix via a conveyor line for surface impurity removal; S11: The conveyor line transports the plate through one side of the grinding equipment for side grinding. The grinding equipment is set on the same side as the identification equipment in step 2. The grinding equipment is a grinding wheel machine or a belt sander; The impurity removal process involves using high-pressure airflow to blow away dust, sand, glass, and metal debris adhering to the surface of the board. S2: The impurity-removed boards are conveyed to the identification equipment by the conveyor line for material classification and identification, and then different types of boards are conveyed to the corresponding designated storage areas for collection via the conveyor line branch lines. S3: After collection, the boards are sent to a high-pressure spray water washing and degreasing equipment through a conveyor line to remove surface oil, dust and attachments, and then sent to a low-temperature hot air drying channel to remove residual moisture. S31: The board material is soaked in a soaking tank to soften stubborn stains; S32: Multi-angle high-pressure spraying washes the surface of the board, thoroughly removing oil, mud and aged glue from the surface of the board. S321: Multi-angle high-pressure airflow blows onto the surface of the board to remove free moisture from the board surface; S33: The board is sent into the low-temperature hot air drying channel to thoroughly dry the residual moisture on the board surface.

[0006] S4: Depending on the type of board material, use low-temperature hot air with corresponding temperature parameters to activate and soften the interlayer adhesive layer, and then tear it at low speed and gently knead it to achieve the interlayer loosening and separation of the plastic substrate and the surface film and aged adhesive layer. S5: The dissociated mixture is fed into a combination of gravity flotation separator and intelligent air separator. Through gradient separation based on density and weight differences, the film, glue blocks, dust and light and heavy impurities are removed to obtain pure plastic substrate fragments. S51: The board is sent into a low-temperature hot air activation furnace for low-temperature hot air activation and softening. If the board is a PVC coated plastic board, the activation temperature is 75-85℃; If the board is a PP film-coated plastic board, the activation temperature is 80-90℃; If the board is a PE coated plastic board, the activation temperature is 70-80℃; S52: The activated board is fed into a low-speed shredder for uniform sheet cutting; The preferred speed of the low-speed shredder is 80-120 r / min, and the cut sheet material is in the shape of a 5-8 cm square sheet. S53: The cut sheet is fed into a flexible kneading machine to gently break it up and knead it. The bottom vibrating screen removes loose residual glue and film debris in real time, so that the rigid plastic substrate is completely separated from the surface film and aged glue layer. The whole process is a purely physical operation with no damage to the substrate and no glue layer embedded. S6: The sorted plastic substrate fragments are sent to an ultrasonic fine cleaning machine to remove trace amounts of residual adhesive and fine stains from the surface and crevices. After fine cleaning, the surface is dried at low temperature to remove residual moisture. Furthermore, after the plastic substrate fragments are removed by high-frequency vibration in an ultrasonic cleaning machine, they are first rinsed with running water to remove surface deposits, and then dried at low temperature to remove moisture. S7: Clean and dry plastic substrate fragments are crushed into uniform particles by a pulverizer, then fed into an extruder for melting and extrusion, and finally processed by water cooling to obtain recycled plastic granules.

[0007] Preferably, the conveyor lines for the low-speed shredding sections in steps S1 to S4 are all roller conveyor lines, the conveyor lines from the low-speed shredding section in step S4 to step S7 are all belt conveyor lines, and the conveyor lines for the crusher sections in steps S5 to S7 are mesh belt conveyor lines.

[0008] The beneficial effects achieved by this invention patent are as follows: High-pressure air blowing matrix removes sand, dust, and metal impurities from the surface of the board. Adaptive elastic guide grinding structure straightens the sides of the board, removing burrs, residual glue, and other interfering defects. Near-infrared material identification equipment accurately distinguishes PVC, PP, and PE boards. Automatic classification and collection are achieved through branch line conveyor, effectively avoiding the problems of large errors and serious mixing caused by manual sorting. This ensures the effect of subsequent layered purification from the source and significantly improves the finished product recovery rate and material uniformity.

[0009] Customized low-temperature activation parameters are set for the heat resistance characteristics of different boards, effectively softening composite adhesive layers such as polyurethane, acrylate, and hot melt adhesive, causing the adhesive layers to loosen and detach. At the same time, the low-temperature operation throughout the process will not cause the substrate to deform or degrade due to heat, thus preserving the mechanical properties of the original substrate to the greatest extent. This completely solves the problem of performance degradation of recycled materials in traditional processes, and significantly improves the quality and application value of recycled plastic granules.

[0010] By employing a dissociation method that combines low-speed shearing with biaxial flexible kneading and online impurity removal using a vibrating screen, the substrate, coating, and residual adhesive can be gently separated into layers without substrate damage or embedded adhesive layers. This results in low material loss, high effective recovery rate, simple overall process, and convenient operation and maintenance. It completely solves the problems of high investment and difficult implementation of traditional processes, making it suitable for mass production scenarios of large, medium, and small enterprises.

[0011] The process involves soaking and softening, multi-angle high-pressure spraying, and airflow purging to thoroughly remove oil, mud, and aged adhesive from the surface of the board. It also utilizes density and weight differences to remove heavy impurities and light coating debris and adhesive powder in layers. Finally, ultrasonic high-frequency vibration is used to peel away trace amounts of residual adhesive and stubborn stains from the substrate gaps. After rinsing and drying, high-purity plastic substrate fragments are obtained. This multi-stage precision impurity removal effectively solves the defects of traditional recycled materials, such as high levels of residual impurities and insufficient purity, providing a high-quality raw material guarantee for high-quality granulation.

[0012] This process involves no chemical additives or high-temperature pyrolysis reactions, and produces no toxic or harmful pollutants. It only generates conventional solid debris and impurities, which can be collected and treated uniformly without secondary pollution. Furthermore, the energy consumption of each process is controllable and the operation is clean, which greatly reduces the environmental protection operation and maintenance costs of enterprises and fully complies with the green production standards and environmental protection policy requirements for solid waste recycling. Attached Figure Description

[0013] Figure 1 This is a flowchart of the method for separating and recycling waste composite plastic sheets in Example 1. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings.

[0015] like Figure 1As shown, this invention patent discloses a method for interlayer separation and resource recycling of waste composite plastic sheets, including the following steps: S1: The conveyor line transports the sheet material through a high-pressure air blowing matrix for surface impurity removal; The conveyor line passes through the middle of the high-pressure air blowing matrix, and the output ends of the high-pressure nozzles evenly arranged inside the high-pressure air blowing matrix are all inclined from the outside to the inside towards the input end of the high-pressure air blowing matrix. The high-pressure air blowing matrix is ​​connected to an external high-pressure air source. Surface cleaning includes removing dust, sand, glass, and metal particles adhering to the surface of the board. S11: The conveyor line transports the sheet material through one side of the grinding equipment for side grinding; The conveyor line is equipped with elastic guide plates on both sides. The two elastic guide plates guide the plates on the conveyor line, and the distance between the two elastic guide plates changes with the width of the plates. One of the guide plates has an opening in the middle for the grinding equipment to contact the side of the plate. Preferably, the grinding equipment is either a grinding wheel machine or a belt sander; S2: The conveyor line transports the sheet material to the identification equipment for classification and identification, and then transports different types of sheet material to the designated storage area through the conveyor line branch lines; Film-coated composite plastic sheets include PVC, PP, and PE film-coated plastic sheets; The identification device uses a near-infrared plastic material identification machine and is set at the side of the conveyor line. The identification device and the grinding device are set on the same side. When the board passes through the identification device, the side of the board that is being ground is detected by the identification device. S3: The conveyor line sends the identified and collected boards into a high-pressure spray water washing and degreasing equipment to remove oil, dust and attachments from the surface of the plastic boards. After cleaning, the conveyor line sends the boards to a low-temperature hot air dryer to remove residual moisture. S31: The board material is soaked in a soaking tank to soften stubborn stains; S32: Multi-angle high-pressure spraying washes the surface of the board, thoroughly removing oil, mud and aged glue from the surface of the board. S321: Multi-angle high-pressure airflow blows onto the surface of the board to remove free moisture from the board surface; S33: The board is sent into a low-temperature hot air drying channel to thoroughly dry any residual moisture on the board surface; S4: Based on the current board material category, a differentiated low-temperature hot air activation and softening method is used to soften the interlayer adhesive layer. After activation, the layers are slowly torn apart and gently kneaded to achieve the interlayer loosening and separation of the board substrate, surface coating, and aged adhesive layer. S41: The board is sent into a low-temperature hot air activation furnace for low-temperature hot air activation and softening. If the board is a PVC coated plastic board, the activation temperature is 75-85℃ and the constant temperature activation time is 35-50 minutes. This is to specifically soften the polyurethane and acrylic composite adhesive layer. After the adhesive layer is softened, it is in a relaxed state and does not have curing brittleness. If the board is a PP film-coated plastic board, the activation temperature is 80-90℃ and the constant temperature activation time is 30-45 minutes, which is suitable for the high heat resistance of PP board and softens the surface composite hot melt adhesive. If the board is a PE coated plastic board, the activation temperature is 70-80℃, the constant temperature activation time is 40-50min, and the low temperature slow softening is used to avoid the PE substrate from softening and deforming due to heat. S42: The activated board is fed into a low-speed shredder for uniform sheet cutting; The optimal rotational speed for a low-speed shredder is 80–120 r / min; The cut sheet material is in the form of square sheets of 5-8 cm. S43: The cut sheet is fed into a flexible kneading machine to gently break it up and knead it. The bottom vibrating screen removes loose residual glue and film debris in real time, so that the rigid plastic substrate is completely separated from the surface film and aged glue layer. The whole process is a purely physical operation with no damage to the substrate and no glue layer embedded. Preferably, the flexible kneading machine is a dual-shaft flexible kneading machine; S5: The dissociated mixture is fed into a combination of gravity flotation separator and intelligent air separator. Through gradient separation based on density and weight differences, the detached film, glue blocks, dust and light and heavy impurities are removed to obtain pure plastic substrate fragments. Specifically, the conveyor line evenly distributes the dissociated mixture into a gravity flotation separator. By utilizing the density difference between the plastic substrate and the adhesive layer and impurities, the pure plastic substrate floats up while the heavy adhesive blocks and mud and sand impurities sink down, thus completing the complete separation of heavy impurities. Among them, after the pure material floats to the surface and is drained, it is sent to an intelligent variable frequency air separator. The air speed is automatically adjusted according to the particle size of the material to blow away lightweight coating debris, fine adhesive powder and surface dust, and finally produce plastic substrate sheets. S6: The conveyor line sends the sorted plastic substrate sheets into the ultrasonic cleaning machine to remove trace amounts of residual adhesive and fine stains from the surface. After the cleaning is completed, the sheets are dried at low temperature to remove water. Specifically, the ultrasonic cleaning machine uses high-frequency ultrasonic vibration to clean the sorted plastic substrate sheets, thereby removing trace amounts of residual adhesive, fine dust, and stubborn stains from the surface and crevices of the substrate. After cleaning, the plastic substrate sheets are sent to a low-temperature drying channel to remove surface moisture. Preferably, after the plastic substrate sheet has been thoroughly cleaned, it is rinsed with running water to remove surface deposits and then sent into a low-temperature drying channel to remove surface moisture. S7: Clean and dry plastic substrate fragments are fed into a crusher via a conveyor line and crushed into uniform particles. Then, they are conveyed by a conveyor belt to an extrusion granulator for melting and extrusion, followed by water cooling to prepare recycled plastic granules.

[0016] Preferably, the conveyor lines for the low-speed shredding sections in steps S1 to S4 are all roller conveyor lines, the conveyor lines from the low-speed shredding section in step S4 to step S7 are all belt conveyor lines, and the conveyor lines for the crusher section in steps S5 to S7 are mesh belt conveyor lines.

[0017] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for interlayer separation and resource recycling of waste composite plastic sheets, characterized in that: Includes the following steps: S1: The sheet material is conveyed through the high-pressure air blowing matrix via a conveyor line for surface impurity removal; The impurity removal process involves using high-pressure airflow to blow away dust, sand, glass, and metal debris adhering to the surface of the board. S2: The impurity-removed boards are conveyed to the identification equipment by the conveyor line for material classification and identification, and then different types of boards are conveyed to the corresponding designated storage areas for collection via the conveyor line branch lines. S3: After collection, the boards are sent to a high-pressure spray water washing and degreasing equipment through a conveyor line to remove surface oil, dust and attachments, and then sent to a low-temperature hot air drying channel to remove residual moisture. S4: Depending on the type of board material, use low-temperature hot air with corresponding temperature parameters to activate and soften the interlayer adhesive layer, and then tear it at low speed and gently knead it to achieve the interlayer loosening and separation of the plastic substrate and the surface film and aged adhesive layer. S5: The dissociated mixture is fed into a combination of gravity flotation separator and intelligent air separator. Through gradient separation based on density and weight differences, the film, glue blocks, dust and light and heavy impurities are removed to obtain pure plastic substrate fragments. S6: The sorted plastic substrate fragments are sent to an ultrasonic fine cleaning machine to remove trace amounts of residual adhesive and fine stains from the surface and crevices. After fine cleaning, the surface is dried at low temperature to remove residual moisture. S7: Clean and dry plastic substrate fragments are crushed into uniform particles by a pulverizer, then fed into an extruder for melting and extrusion, and finally processed by water cooling to obtain recycled plastic granules.

2. The recycling process for waste coated composite plastic sheets according to claim 1, characterized in that: Step S1 further includes sub-step S11: the conveyor line transports the plate through one side of the grinding equipment for side grinding, and the grinding equipment is set on the same side as the identification equipment in step 2.

3. The recycling process for waste coated composite plastic sheets according to claim 2, characterized in that: The grinding equipment is a grinding wheel machine or a belt sander.

4. The recycling process for waste coated composite plastic sheets according to claim 1, characterized in that: Step S3 includes the following sub-steps: S31: The board material is soaked in a soaking tank to soften stubborn stains; S32: Multi-angle high-pressure spraying washes the surface of the board, thoroughly removing oil, mud and aged glue from the surface of the board. S33: The board is sent into the low-temperature hot air drying channel to thoroughly dry the residual moisture on the board surface.

5. The recycling process for waste coated composite plastic sheets according to claim 3, characterized in that: Step S32 further includes sub-step S321: blowing high-pressure airflow at multiple angles onto the surface of the board to remove free moisture from the surface of the board.

6. The recycling process for waste coated composite plastic sheets according to claim 1, characterized in that: Step S4 includes the following sub-steps: S51: The board is sent into a low-temperature hot air activation furnace for low-temperature hot air activation and softening. S52: The activated board is fed into a low-speed shredder for uniform sheet cutting; S53: The cut sheet is fed into a flexible kneading machine to gently break it up and knead it. In conjunction with the bottom vibrating screen, loose residual glue and film debris are removed in real time, so that the rigid plastic substrate is completely separated from the surface film and aged glue layer. The whole process is a purely physical operation with no damage to the substrate and no glue layer embedded.

7. The recycling process for waste coated composite plastic sheets according to claim 5, characterized in that: In step S51: If the board is a PVC coated plastic board, the activation temperature is 75-85℃; If the board is a PP film-coated plastic board, the activation temperature is 80-90℃; If the board is a PE coated plastic board, the activation temperature is 70-80℃.

8. The recycling process for waste coated composite plastic sheets according to claim 5, characterized in that: In step S52, the preferred speed of the low-speed shredder is 80-120 r / min, and the cut sheet material is in the shape of a square sheet of 5-8 cm.

9. The recycling process for waste coated composite plastic sheets according to claim 1, characterized in that: In step S6, after the plastic substrate fragments are cleaned by high-frequency vibration of an ultrasonic cleaning machine, they are first rinsed with running water to remove surface deposits, and then dried at low temperature to remove moisture.

10. The recycling process for waste coated composite plastic sheets according to any one of claims 1-9, characterized in that: The conveyor lines for the low-speed shredding sections in steps S1 to S4 are all roller conveyor lines, the conveyor lines from the low-speed shredding section in step S4 to step S7 are all belt conveyor lines, and the conveyor lines for the crusher sections in steps S5 to S7 are mesh belt conveyor lines.

Images