Search

EP-4741450-A1 - A SYSTEM AND METHOD OF REMOVING IMPURITIES FROM WASTE POLYMER RAW MATERIAL

EP4741450A1EP 4741450 A1EP4741450 A1EP 4741450A1EP-4741450-A1

Abstract

A system for the removal of impurities from waste polymer raw material, characterised in that it comprises the following components: raw material racks (1), PH vessels (2), a reactor vessel (3), buffers (4), a vacuum pump unit and a cyclone (5), a silo for unsuitable material (6), a silo for purified material (7), wherein the PH vessels (2) are located above the reactor vessel (3), the buffers (4) are located under the reactor vessel (3), the vacuum pump unit and the cyclone (5) are located next to the reactor vessel (3), the silos for unsuitable material (6) and purified material (7) are located under the buffers (4). A method of removing impurities from waste polymer raw material, characterised in that it is implemented using the system for the removal of impurities from waste polymer raw material.

Inventors

  • Termanowski, Tomasz
  • Chmielnicki, Blazej

Assignees

  • T&R BIOEKO Sp. z o.o.

Dates

Publication Date
20260513
Application Date
20241108

Claims (12)

  1. A system for the removal of impurities from waste polymeric raw material, characterised in that it consists of raw material racks (1), PH vessels (2), a reactor vessel (3), buffers (4), a vacuum pump unit and a cyclone (5), a silo for unsuitable material (6) and a silo for purified material (7), wherein the PH vessels (2) are located above the reactor vessel (3), the buffers (4) are located under the reactor vessel (3), the vacuum pump unit and the cyclone (5) are located next to the reactor vessel (3), the silos for unsuitable material (6) and purified material (7) are located under the buffers (4).
  2. The system according to claim 1, characterised in that the reactor vessel (3) is made of metal.
  3. The system according to any one of claims 1 to 2, characterised in that the ratio between the height of the reactor vessel and its diameter is between 3:2 and 5:1, while the volume of the reactor vessel is between 0.1 m 3 and 7m 3 .
  4. The system according to any one of claims 1 to 4, characterised in that the bottom of reactor vessel (3) is preferably provided with a connection for the feeding of gas used in the process of the removal of impurities from the waste polymer raw material.
  5. A method for the removal of impurities from waste polymeric raw material, characterised in that it is implemented using the system according to claims 1 to 4 in accordance with the following steps: a) the raw material is hung on racks (1) and then; b) the raw material is hauled into PH vessels (2), where it is heated and cleaned of any dust, wherein the dust is fed into cyclone (5), then; c) after reaching a preset initial temperature, the raw material is discharged into reactor vessel (3); d) In vessel (3), the raw material is heated to a higher temperature in vacuum conditions, then; e) the raw material is unloaded into buffers (4) and then f) the raw material is appropriately fed into the silo for unsuitable material (6), or into the silo for purified material (7).
  6. The method according to claim 5, characterised in that the temperature of the heating process in the reactor is between the temperature 40°C lower than the melting point of waste polymer and the temperature of the melting point of the waste polymer.
  7. The method according to claim 11, characterised in that the waste polymer raw material is polyethylene terephthalate (PET) obtained from food trays and the temperature of the heating process in the reactor is between 180°C and 230°C.
  8. The method according to any one of claims 10 to 12, characterised in that the value of vacuum in the reactor chamber is between 0.1 mbar and 1 bar.
  9. The method according to any one of claims 10 to 13, characterised in that the used gas is a noble gas or an inert gas.
  10. The method according to claim 14, characterised in that the used gas is selected from a group consisting of nitrogen, argon, carbon dioxide.
  11. The method according to any one of claims 10 to 15, characterised by the fact that the flow rate of gas through the device per one unit of the reactor base area is between 100 ml/min·m 2 and 50 l/min·m 2 .
  12. The method according to any one of claims 10 to 16, characterised in that process times range from 5 min to 240 min.

Description

The present invention relates to a system for the removal of impurities from waste polymer raw material and a method of removing impurities from waste polymer raw material implemented using this system. Polyethylene terephthalate (PET) is a plastic material that belongs to the polyester group and which, due to its favourable physical properties, has found a wide range of applications, such as the production of packaging for foodstuffs, cosmetics and industrial products. PET's popularity as a packaging material derives from a number of important properties of this polymer, notably its glass-like transparency and low weight, which, combined with its flexibility and mechanical resistance, makes PET packaging shatterproof. It provides a good barrier to gases, which allows PET to be used in the production of packaging materials used for the packing and storage of carbonated beverages. PET can also be used in combination with other materials, such as textile raw materials, to enhance the strength of fabrics. Polyethylene terephthalate was first discovered in the 1950s. It was initially used for the production of thin films and was later modified and strengthened with the addition of glass fibre. New technologies were introduced in the production of PET at the start of the 1970s, which facilitated the production of a plastic material that had a triaxial orientation of the polymer structure, to achieve a product that resembles glass in appearance, but is much lighter and unbreakable. This development led to the widespread use of this plastic as a packaging material as a substitute for glass packaging. Polyethylene terephthalate, because of its high molecular weight, has good mechanical properties that give it suitable flexibility. It is also characterised by a hard surface, good sliding and dielectric properties, as well as chemical resistance to weak acids and alkaline solutions, oils and fats. It is not resistant to concentrated acids and alkaline solutions, or to prolonged exposure to hot water. The sterilisation of PET products is carried out in an ethylene oxide atmosphere, or by irradiation. PET is obtained through the reaction of terephthalic acid (PTA) or its dimethyl terephthalate (DMT) ester with ethylene glycol (EG) in the presence of a metallic catalyst. Antimony trioxide is most often used as this catalyst, although titanium, germanium, cobalt, manganese, magnesium and zinc salts can also be used. A certain amount of catalyst may remain in the final product, which must be taken into account when assessing the healthiness of products manufactured using this polymer. PET, a polymer with a high molecular weight of approximately 25,000, is obtained during the second polycondensation phase. Volatile impurities, acetaldehyde and free glycols are removed during this process. Ethylene glycol residues are removed via vacuum distillation, while terephthalic acid is removed by way of multiple crystallisation. Once the polymer has been formed, it is very difficult to remove residual impurities from it, so it is essential to use base raw materials of sufficient purity for the production of polymers, with the aim of obtaining quality levels that are required in food packaging materials. PET is usually processed by way of injection moulding at 260-290°C, while films, sheets and fibres are formed by way of extrusion. In order to improve its mechanical strength, films are subjected to biaxial orientation by way of stretching. PET belongs to the group of semi-crystalline polymers that, when heated to temperatures above approximately 70°C, melt from a hard, glass-like material into a flexible, rubber-like structure (rubbery state). In this form, macromolecular polymer chains can be formed by stretching in one direction to form fibres, or in two directions to produce films or bottles. The rapid cooling of the material results in its solidification, which allows the permanent formation of packaging such as bottles, jars, containers. Keeping the material in a stretched state at temperatures above approx. 70°C leads to its gradual crystallisation, and as a result it becomes more opaque, more brittle and less elastic. In this form, it is known as crystalline PET (CPET), a plastic that is more heat-resistant and is used in the production of trays and containers used in the catering industry as disposable packaging. The therfmoforming process involves the use of PET that contains a small amount of the isophthalic acid comonomer, or APET. APET products gradually crystallise when heated above the glass transition temperature, or when subjected to slow cooling. PETG (a copolymer of terephthalic acid with two ethylene glycols and cyclohexanedimethanol) is an amorphous polyester in all conditions. In comparison with APET, the comonomer content in PETG is higher and can reach up to 30%. PETG has good optical properties, but poorer barrier properties and is easier to process, mainly due to its lower softening point. PETG is used for t