Method and apparatus for recycling and reuse plastic foam

Abstract

This invention discloses a method and apparatus for recycling plastic foam, comprising steps such as sorting, crushing, filling, preheating, hot pressing, and cooling demolding. The method involves directly filling plastic foam particles sorted according to their melting points into a mold with side vents. A preheating air unit provides hot air above the melting point, which is introduced into the mold cavity through the side vents, melting the surface of the particles. The hot air is then guided back through a return air hood above the mold, forming a hot air circulation system to improve heating efficiency and reduce energy consumption. The mold is then moved to a hot pressing unit, where a liftable pressure seat drives a heating plate to apply corresponding pressure and temperature for melting and pressing, fusing the plastic foam particles into a dense and strong recycled plastic foam board. This recycling process does not require the addition of foaming agents or new raw materials, simplifying operation, reducing energy consumption, and possessing good industrial applicability.

Claims

1. A method for recycling plastic foam, comprising the following steps: a sorting step: sorting the plastic foam according to its melting point and material; a crushing step: crushing the plastic foam to form plastic foam fragments; a filling step: filling the mold with the plastic foam fragments located at the filling position; and a preheating step: heating air to a temperature higher than the melting point of the plastic foam fragments using a preheating air unit, wherein... The mold has a plurality of side air holes on its side wall, and hot air is forced into the mold through the plurality of side air holes to make the surface of the plastic foam particles reach a molten state. The hot air is also recovered through a return air hood set above the mold, so that the hot air passes through and is guided to the return air hood to form a hot air circulation. Hot pressing step: The mold is hot pressed to shape by a heating plate with set pressure and temperature. Cooling and demolding step: After the shaping is completed, the plastic foam board is taken out.

2. The method for recycling 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).

3. The method for recycling plastic foam as described in claim 2, 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.

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

5. The method for recycling plastic foam as described in claim 1, wherein, The return air hood has multiple air holes to guide hot air through and promote hot air circulation.

6. The method for recycling plastic foam as described in claim 1, wherein, In the hot pressing step, the set temperature of the upper heating plate is 20°C to 100°C higher than the melting point of the plastic foam granules.

7. The method for recycling 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.

8. A method for recycling plastic foam as described in claim 1, wherein, Prior to the filling step, a release agent is applied to the bottom of the mold cavity.

9. A method for recycling plastic foam as described in claim 1, wherein, In the hot pressing step, the bottom of the upper heating plate of a hot pressing unit is coated with a release agent.

10. A device for recycling plastic foam, comprising: at least one mold, including a mold cavity and a filler space for accommodating foam fragments, and further including a plurality of side air holes formed on the sidewall of the mold cavity; a preheating air unit, including a heater and a fan, the fan forcibly sending air heated by the heater into the mold to preheat and melt the plastic foam fragments in the mold; a return air hood, disposed on the top of the mold and connected to the preheating air unit, for recovering hot air in the mold to form a hot air circulation; and a hot pressing unit, including a pressure seat and an upper heating plate, the pressure seat driving the upper heating plate to pressurize and shape the plastic foam fragments in the mold, the upper heating plate maintaining the melting temperature of the foam fragments.

11. The apparatus for recycling plastic foam as described in claim 10, wherein, The return air hood has a plurality of air holes to guide hot air through and promote hot air circulation.

12. The plastic foam recycling apparatus as described in claim 10, wherein, The bottom of the mold cavity is coated with a release agent.

13. The plastic foam recycling apparatus as described in claim 10, wherein, The bottom of the upper heating plate of the hot pressing unit is coated with a release agent.

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