PLASTIC MATERIALS AND WASTE RECYCLING DEVICE

Abstract

A device for recycling plastic materials and waste comprising: a compactor (2) for feeding a first single-screw extruder (3) and a second twin-screw extruder (5) connected to the outlet of the first extruder (3) by means of a molten material pump (4), characterized in that it further comprises at least a first filter (A) at the outlet of the first extruder (3) before the molten material pump (4) and at least a second filter (C) at the outlet of the second extruder (5).

Description

PLASTIC MATERIALS AND WASTE RECYCLING DEVICE TECHNICAL SECTOR The present invention relates to a device for recycling plastic materials and waste in film format, shredded or not, with very low densities and / or high moisture content (up to 12% w / w). STATE OF THE ART United States patent application number US 2022 / 0009140 A1 describes an injection device for a molding machine that includes a molding compound hopper and an injection unit. The molding compound hopper is configured to supply a plasticized mass and to eject the plasticized mass through a discharge opening. A connecting device is coupled to the discharge opening of the molding compound hopper and a feed opening of the injection unit, and is configured to direct the plasticized mass from the molding compound hopper to the injection unit. The connecting device includes a hinged element, and the hinged element allows relative movement between the molding compound hopper and the injection unit. This document essentially describes a plastic injection molding machine that incorporates a plasticizing screw which literally melts the plastic material. The molten material then passes through a filtration device and subsequently through a degassing device. The filtration stage cleans the material, while the degassing stage removes the gas created by contamination of the recycled plastic material. This solution is suitable for rigid plastics, but it is not suitable for film-formed plastics, which constitute the majority of post-consumer plastics and are also the most difficult to recycle. Therefore, a device and method are required to recycle these types of plastics. Document CN 107745462 A relates to a system and method for the treatment and recycling of plastics. The described system comprises a mixer connected to a screw feeder (a compactor for feeding), followed by the first single-screw or twin-screw extruder, which is provided with a first filter at its outlet. Following the first filter is the molten material pump, followed by a filter connected to the first main feed port of the second twin-screw extruder. The feeding machine is connected to the second feed port. The discharge port of the second twin-screw extruder is connected to the pelletizing die head, which is in turn followed by the pelletizing die and the pelletizer. The pelletizer is provided with an air blower. However, this document does not describe a filter at the outlet of the second extruder. EXPLANATION OF THE INVENTION The object of the present invention is a tandem extrusion device, where the first extruder is a single-screw extruder and the second extruder is a twin-screw extruder. Before the first extruder, the device includes a compactor, making it possible to work with plastic films. In the prior art, a single filter is used between the first and second extruders, so that, once the material is filtered, the molten material is passed to the second twin-screw extruder to improve the product's quality. The present invention advantageously includes at least one additional filter, preferably continuous, at the end of the twin-screw extruder to obtain superior quality extruded material. Furthermore, another filter is advantageously added after the first filter and the molten material pump, just before the material enters the second extruder. Thanks to this additional filter, less contaminated material is obtained before entering the second extruder, which could optionally have a filter at its end. Finally, in a particular embodiment, a degassing device is added between the first and second extruders. Throughout the description and claims, the word "comprises" and its variants are not intended to exclude other technical features, additives, components, or steps. For those skilled in the art, other objects, advantages, and features of the invention will become apparent partly from the description and partly from the practice of the invention. The following examples and drawings are provided for illustrative purposes and are not intended to restrict the present invention. Furthermore, the present invention covers all possible combinations of the particular and preferred embodiments indicated herein. BRIEF DESCRIPTION OF THE FIGURES Next, a series of drawings are briefly described that help to better understand the invention and that are expressly related to an embodiment of said invention that is presented as a non-limiting example thereof. Figure 1 - Shows the plastic materials and waste recycling device of the invention. EXPLANATION OF ONE WAY OF CARRYING OUT THE INVENTION As shown in the attached figure, the device of the invention comprises a feed belt 1 that feeds a compactor 2 to feed a first single-screw extruder 3, with the particularity that, before the molten material pump 4, there is a filter A, preferably a continuous filter. In one particular embodiment, an additional filter B is provided after the molten material pump 4 and before the second twin-screw extruder 5. Finally, a filter C is advantageously incorporated at the outlet of the second extruder 5 to improve the quality of the resulting product. Optionally, a degassing device may be placed between the first extruder 3 and the second extruder 5. However, in another particular embodiment of the invention, it is possible to place one or more degassing devices in the first extruder 3 and / or in the second extruder 5.

Claims

1. A device for recycling plastic materials and waste comprising: a compactor (2) for feeding a first single-screw extruder (3) and a second twin-screw extruder (5) connected to the outlet of the first extruder (3) by means of a molten material pump (4), characterized in that it further comprises at least a first filter (A) at the outlet of the first extruder (3) before the molten material pump (4) and at least a second filter (C) at the outlet of the second extruder (5).

2. The device according to claim 1 comprising a third filter (B) at the outlet of the molten material pump (4) before the inlet of the second twin-screw extruder (5).

3. The device according to claim 1 or 2 comprising a degassing device between the first extruder (3) and the second extruder (5). 4.The device according to any one of claims 1 to 3 comprising one or more degassing devices in the first extruder (3), in the second extruder (5), or in the first and second extruder (3, 5).