Method and apparatus for recycling and reprocessing plastic foam

Abstract

This invention discloses a method and apparatus for recycling and remanufacturing plastic foam. It is suitable for classifying, preheating, and hot-pressing cut edges and waste generated in industrial processes to produce recycled plastic foam boards. The method includes classification, crushing, filling, preheating, hot-pressing, and cooling / demolding steps. By classifying according to the melting point of the material, the crushed plastic foam particles are directly filled into a mold. Hot air supplied by a preheating air unit melts the surface layer, and then the hot-pressing unit applies pressure at set temperature and pressure to shape the foam. After cooling, the foam is demolded to complete the recycling process. The apparatus includes a mold, a preheating air unit, a return air hood, a hot-pressing unit, and a lifting seat. Side air vents, top air vents, and a return air hood are provided to create hot air circulation and improve heating efficiency. The molds can be configured alternately, allowing different molds to simultaneously perform the filling, preheating, and hot-pressing processes, achieving a continuous process.

Claims

1. A method for recycling and remanufacturing plastic foam, comprising the following steps: A sorting step: sorting the plastic foam according to its material and melting point; A crushing step: crushing the plastic foam to form plastic foam fragments; A filling step: a mold is located at the filling position, a bottom template is first set inside the mold, the plastic foam fragments are then filled into the mold, and a top template is set on top to limit the plastic foam fragments; A preheating step: heating air to a temperature higher than the melting point of the plastic foam fragments using a preheating air unit, and forcibly sending the hot air into the mold to make the surface of the plastic foam fragments reach a molten state; Hot pressing step: Move the mold to the hot pressing position of a hot pressing unit, and press and shape the mold by setting the temperature and pressure of the upper heating plate and the lower heating plate; and cooling and demolding step: After the shaping is completed, raise the bottom template of the mold to the mold opening, and take it out together with the top template and the bottom template to make plastic foam board, and demold it after it cools to room temperature.

2. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, The system has at least two molds. When one mold is performing a hot pressing step, the other mold simultaneously performs a filling step and a preheating step to alternate operations and improve production efficiency. After one mold completes the cooling and demolding step, it returns to the filling position, while the other mold moves to the hot pressing position.

3. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, The plastic foam material is one of polyethylene (PE), polypropylene (PP) or ethylene propylene diene monomer (EPDM).

4. The method for recycling and remanufacturing plastic foam as described in claim 3, wherein, The main plastic foam particles are made of polyethylene, polypropylene or ethylene propylene diene monomer (EPDM) rubber, and after the crushing step, a plurality of auxiliary plastic foam particles with melting points within ±50°C of the melting point of the main plastic foam particles are added.

5. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, The mold has a plurality of side air holes on its side wall to allow hot air to be sent into the mold through the side air holes. The top plate has a plurality of upper air holes and recovers hot air through one of the return air hoods located above the mold to form a hot air circulation. The upper air holes are used to allow hot air to pass through and be guided to the return air hood.

6. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, The mold has a plurality of side air holes on its side wall to allow hot air to be sent into the mold through the side air holes. The top platen has a mesh structure and recovers the hot air through one of the return air hoods located above the mold to form a hot air circulation. The top platen has a mesh structure to allow the hot air to pass through and be guided to the return air hood.

7. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, Before the filling step, a release agent is applied to the surfaces of the top template and the bottom template.

8. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, The preheating step lasts for 10 to 40 minutes, and the hot air temperature is 20°C to 100°C higher than the melting point of the plastic foam granules.

9. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, In the hot pressing step, the set temperatures of the upper heating plate and the lower heating plate are both 20°C to 100°C higher than the melting point of the plastic foam granules.

10. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, In the hot pressing step, the upper heating plate is pressed downward by a liftable pressure seat.

11. The method for recycling and remanufacturing plastic foam as described in claim 10, wherein, In the cooling and demolding step, the bottom template is lifted upward to the mold opening by a liftable lifting seat, so that the top template, the bottom template and the recycled plastic foam board are taken out together to the cooling area.

12. The method for recycling and remanufacturing plastic foam as described in claim 11, wherein, The pressurizing seat and the lifting seat can automatically return to their original positions after the steps are completed, so that the filling and preheating steps of the next batch of plastic foam granules can be carried out simultaneously.

13. The method for recycling and remanufacturing plastic foam as described in claim 1, wherein, In the cooling and demolding step, the plastic foam board can only be demolded from the top mold and the bottom mold after it has cooled to room temperature.

14. A plastic foam recycling and reprocessing apparatus, comprising: at least one mold, including a mold cavity, and a bottom template and a top template sequentially arranged in the mold cavity, and a filler space for accommodating foam fragments; a preheating air unit, including a heater and a fan, wherein the fan forces air heated by the heater into the mold to preheat and melt the plastic foam fragments in the mold; a hot pressing unit, including a pressure seat, an upper heating plate and a lower heating plate, wherein the pressure seat drives the upper heating plate to press and shape the plastic foam fragments in the mold, the lower heating plate is disposed below the mold, and the upper heating plate and the lower heating plate maintain the fusion temperature of the foam fragments; and a lifting seat disposed below the mold to lift the bottom template of the mold to the mold opening after shaping, so that the recycled plastic foam board and the top template and the bottom template are removed together for cooling.

15. The apparatus for recycling and remanufacturing plastic foam as described in claim 14, wherein, It includes at least two molds, wherein when one of the molds is hot pressing, the other mold is preheated simultaneously, so as to perform alternating operations to improve production efficiency.

16. The apparatus for recycling and remanufacturing plastic foam as described in claim 14, wherein, The mold also includes a plurality of side air holes and a plurality of top air holes. The side air holes are formed on the side wall of the mold cavity, and the top air holes are formed on the top template. It also includes a return air hood, which is disposed on the top of the mold and communicates with the preheating air unit to recover the hot air in the mold that has passed through the top air holes of the top template to form a hot air circulation.

17. The apparatus for recycling and remanufacturing plastic foam as described in claim 14, wherein, The mold also includes a plurality of side air holes formed on the side wall of the mold cavity. The top platen has a mesh structure and also includes a return air hood, which is disposed on the top of the mold and communicates with the preheating air unit to recover the hot air in the mold that passes through the mesh structure of the top platen to form a hot air circulation.

18. The apparatus for recycling and remanufacturing plastic foam as described in claim 14, wherein, Both the top template and the bottom template have a release agent layer on their surfaces to facilitate demolding of the recycled plastic foam board.

19. The apparatus for recycling and remanufacturing plastic foam as described in claim 14, wherein, The mold base plate lifting mechanism has an automatic reset function and is linked with the hot pressing unit so that after one mold completes cooling and demolding, it automatically returns to the filling position and simultaneously starts another mold for hot pressing.

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