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WO-2026093656-A1 - REMOVAL OF FLAME RETARDANTS FROM RECYCLED PLASTICS

WO2026093656A1WO 2026093656 A1WO2026093656 A1WO 2026093656A1WO-2026093656-A1

Abstract

A method is disclosed for removing flame retardants from recycled plastics mate- rial. The method comprises obtaining recycled plastics material in a particulate form. The recycled plastics material in the particulate form is subjected to a first solvent extraction step with a first solution containing alkali metal hydroxide in an 5 amount of 1 to 10 wt-%, wherein the first solvent extraction step is performed at an absolute pressure of 1 to 6 bar, preferably above 1 bar, at a temperature of 90 to 160 oC, and above the glass transition temperature of the recycled plastics ma- terial, to extract flame retardants from the recycled plastics material to the first solution thereby reducing the flame retardants content of the recycled plastics ma-10 terial. The recycled plastics material having a reduced flame retardants content may then be recovered e.g. by filtering.

Inventors

  • KUUTTI, LAURI
  • KARJALAINEN, Erno
  • PELTO, JANI
  • Tenhunen-Lunkka, Anna
  • Rytöluoto, Ilkka
  • KOKKONEN, JUHA

Assignees

  • TEKNOLOGIAN TUTKIMUSKESKUS VTT OY

Dates

Publication Date
20260507
Application Date
20251031
Priority Date
20241101

Claims (20)

  1. 1. A method for removing flame retardants from recycled plastics material, obtaining recycled plastics material in a particulate form; subjecting the recycled plastics material in the particulate form to a first solvent extraction step with a first solution containing alkali metal hydroxide in an amount of 1 to 10 wt-%, wherein the first solvent extraction step is performed at an absolute pressure of 1 to 6 bar, at a temperature of 90 to 160 °C, and above the glass transition temperature of the recycled plastics material, to extract flame retardants from the recycled plastics material to the first solution thereby reducing the flame retardants content of the recycled plastics material; and recovering the recycled plastics material having a reduced flame retardants content.
  2. 2. A method according to claim 1, wherein the first solution contains alkali metal hydroxide in an amount of 3 to 8 wt-%.
  3. 3. A method according to claim 1 or 2, wherein the first solvent extraction step is performed at a temperature of 100 to 150 °C.
  4. 4. A method according to any preceding claim, wherein the obtained recycled plastics material in the particulate form has an average particle size in a range of 0.25 mm to 5 mm, preferably 0.5 mm to 2 mm.
  5. 5. A method according to any preceding claim, comprising recovering the recycled plastics material having the reduced flame retardants content by filtration, decantation, or centrifugation.
  6. 6. A method according to any preceding claim, wherein after the first solvent extraction step, the method comprises subjecting the recovered recycled plastics material having the reduced flame retardants content to at least one further solvent extraction step with a further solution containing alkali metal hydroxide, and/or one or more Cl to C4 alcohol, in a total amount of 1 to 20 wt-%, wherein the at least one further solvent extraction step is performed at an absolute pressure of 1 to 6 bar, at a temperature of 90 to 160 °C, and above the glass transition temperature of the recycled plastics material, to further extract flame retardants from the recycled plastics material to the further solution thereby further reducing the flame retardants content of the recycled plastics material; and recovering the recycled plastics material having a further reduced flame retardants content.
  7. 7. A method according to claim 6, wherein the further solution contains alkali metal hydroxide in an amount of 1 to 10 wt-%, preferably 3 to 8 wt-%, wherein the at least one further solvent extraction step is performed at a temperature of 100 to 160 °C preferably 100 to 150 °C.
  8. 8. A method according to claim 6, wherein the further solution contains one or more Cl to C4 alcohol in an amount of 1 to 10 wt-%, preferably 3 to 8 wt-%, wherein the at least one further solvent extraction step is performed at a temperature of 90 to 100 °C.
  9. 9. A method according to claim 6 or 8, wherein the Cl to C4 alcohol is one or more of ethanol and isopropanol, preferably isopropanol.
  10. 10. A method according to claim 6, 7, 8 or 9, comprising recovering the recycled plastics material having the further reduced flame retardants content by filtration, decantation, or centrifugation.
  11. 11. A method according to claim 6, 7, 8, 9 or 10, comprising grinding the recycled plastics material having the reduced flame retardants content to an average particle size of 0.25 to 1 mm before the further solvent extraction step.
  12. 12. A method according to any preceding claim, wherein the recycled plastics material contains one or more of ABS, PS, Hl-PS, PE, PP, and PET.
  13. 13. A method according to any preceding claim, wherein the method comprises crushing recycled plastics by using a grinder or a pulverizer to obtain the particulate form of the recycled plastics material.
  14. 14. A method according to any preceding claim, wherein the flame retardants comprise brominated flame retardants.
  15. 15. A method according to any preceding claim, wherein upon the brominated flame retardants content of the recycled plastics material being 5000 ppm or less, the method comprises subjecting the recycled plastics material to the first solvent extraction step and optionally to at least one further solvent extraction step.
  16. 16. A method according to any preceding claim, wherein upon the brominated flame retardants content of the recycled plastics material being above 5000 ppm, the method comprises subjecting the recycled plastics material to the first solvent extraction step and at least one further solvent extraction step.
  17. 17. A method according to any preceding claim, wherein the method comprises extracting flame retardants from the recycled plastics material to the solution without dissolving the recycled plastics material.
  18. 18. A method according to any preceding claim, wherein the method comprises recycling at least part of the first solution, or further solution to the first or further solvent extraction step.
  19. 19. A method according to any preceding claim, wherein the method comprises conducting each solvent extraction step for 1 to 2 hours, preferably about 1 hour.
  20. 20. A method according to any preceding claim, wherein the alkali metal hydroxide is at least one of NaOH and KOH, preferably NaOH.

Description

REMOVAL OF FLAME RETARDANTS FROM RECYCLED PLASTICS FIELD OF THE INVENTION The present invention relates to a method of removing flame retardants from recycled plastics. BACKGROUND ART Polymers are widely used materials. Polymers are found especially in consumer products such as electronics and packaging materials. In Europe 25.8 million tonnes of plastics waste is generated annually. Less than 30 wt% of the plastics waste is collected for recycling. A significant share of the plastics waste is exported from the European Union to other countries for processing. Landfilling (30 wt%] and incineration (39 wt%] are the most common methods for treating plastics waste. Thus, a large amount of valuable material is lost from circulation. Flame retardants are chemical compounds added to plastics in order to prevent or delay the ignition and burning of plastics and to slow down the spread of fire. Halogenated flame retardants may include materials such as bromine and chlorine compounds. Halogenated flame retardants release halogen gases when exposed to high temperatures, interfering with the combustion process, thus actively preventing the fire from spreading. BRIEF DESCRIPTION The scope of protection sought for various example embodiments is set out by the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments. According to an aspect, there is provided a method for removing flame retardants from recycled plastics material, comprising obtaining recycled plastics material in a particulate form, subjecting the recycled plastics material in the particulate form to a first solvent extraction step with a first solution containing alkali metal hydroxide in an amount of 1 to 10 wt-%, wherein the first solvent extraction step is performed at an absolute pressure of 1 to 6 bar, at a temperature of 90 to 160 °C, and above the glass transition temperature of the recycled plastics material, to extract flame retardants from the recycled plastics material to the first solution thereby reducing the flame retardants content of the recycled plastics material, and recovering the recycled plastics material having a reduced flame retardants content. BRIEF DESCRIPTION OF THE DRAWINGS In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which Figure 1 illustrates a method according to an embodiment; Figure 2 shows recycled ABS viscosity measurements results after solvent extraction compared to ABS reference sample; Figure 3 shows recycled PP/PE viscosity measurements results after solvent extraction compared to PP/PE reference sample. DETAILED DESCRIPTION OF EMBODIMENTS The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment's), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Exposure to halogenated flame retardants is associated with a wide range of adverse effects in humans and animals, including lowered IQ (intelligence quotient) in children, cancer, hormone disruption, and other serious health problems. Currently, obstacles for efficient utilization of recycled plastics include safety concerns, low quality of the recycled material, and low recycling rates. The industry is also lacking standards for plastics recycling. A safety concern in plastics recycling is the presence of hazardous substances such as flame retardants including brominated flame retardants, BFR. Therefore, a challenge is to address the presence of hazardous substances such as brominated flame retardants, BFR, in the recycled feedstocks, and provide methods to effectively and safely debrominate the waste for new products. BFR content in plastics waste may be even up to 15 to 20 wt-%. BFRs are mostly hazardous substances, and their circulations is prohibited by legislation. To be able to circulate these challenging yet valuable waste plastics streams, effective debromination without destroying the polymer is desired. It may be desired to decrease the bromine, antimony, and chlorine contents of recycled plastics below the legislative limit (EU) 1000 ppm. It is typically easier to decrease the antimony and chlorine levels from 1300 ppm to below 200 ppm. A more difficult task is to decrease the concentration of bromine compounds in the plastics waste to be below 1000 ppm or below, or 500 ppm or below. Technical plastics typically have higher prices, and current recycling capacity is typically sold out. The movement of legislation towards mandatory recy- clate-content is increasing the demand for technical plastic r