Process for removing lead from plastics material, in particular from PVC recyclates

Abstract

In order to remove lead from plastics material (4), in particular PVC recyclates, the plastics material (4) brought into contact with an alkali hydroxide solution (6) in order to extract lead contained in the plastics material (4) as an alkali plumbate (9) dissolved in the alkali hydroxide solution (6). The alkali hydroxide solution (6) is removed from the plastics material (4) together with the alkaline plumbate (9) dissolved therein, and the lead is separated from the removed alkali hydroxide solution (6) without using ammonia.

Description

[0001] REHBERG HÜPPE + PARTNER - 1 - Originally submitted version 22278PCT 09.01.2026

[0002] RHP Ref.: 22278PCT ZAS6

[0003] Patent application: File number not yet assigned

[0004] Priority 1: 08.01.2025 (DE 102025000056.1)

[0005] Priority 2: 20.02.2025 (DE 102025000623.3)

[0006] Title: Method for removing lead from plastic, especially from recycled PVC

[0007] Applicant: D&G Recycling GmbH

[0008] METHOD FOR REMOVING LEAD FROM PLASTICS, IN PARTICULAR FROM PVC RECYCLATES

[0009] TECHNICAL AREA OF INVENTION

[0010] The invention relates to a method for removing lead from plastic. The plastic in question is, in particular, polyvinyl chloride (PVC).

[0011] Since 2015, lead-based stabilizers have no longer been used in PVC in the European Union. However, PVC originating outside the EU and older PVC sometimes contain significant amounts of the heavy metal lead, up to 5% by weight in flexible PVC and even more than 5% by weight in rigid PVC. This poses a major problem when reusing PVC from recycled sources, as the EU has imposed a limit of 0.1% by weight for lead in most products, including those made from recycled PVC, since November 29, 2023.

[0012] Therefore, there is interest in methods for removing lead from plastic, especially PVC.

[0013] At the same time, there is an interest in isolating the lead contained in plastic, especially PVC, in the purest possible form, in order not only to remove it from the plastic product cycle, but also to be able to recycle it.

[0014] STATE OF THE ART

[0015] A process for the selective recovery of lead, zinc, and calcium from materials containing them as water-insoluble oxides or salts is known from DE 4033232 A1. REHBERG HÜPPE + PARTNER - 2 - Originally filed version 22278PCT 09.01.2026

[0016] Materials are leached with an ammonium solution at boiling temperature. The insoluble solid is separated. The resulting solution is treated with carbon dioxide and ammonia to precipitate lead, zinc, and calcium carbonate separately. The carbon dioxide is recovered from the carbonates by calcination or by leaching in acids. The use of ammonia in this process is considered problematic from an environmental perspective. Released ammonia spreads in the air, reacts with other air pollutants, and forms particulate matter. Ammonia itself and the particulate matter formed in the air endanger human health and damage plants and ecosystems.

[0017] A process for recycling PVC products, particularly PVC flooring and wall coverings, is known from WO 2024 / 134371 A1. The PVC products undergo solvent-based extraction in an extraction vessel to extract, among other things, heavy metals such as lead. Specifically, the PVC products can be brought into contact with a complexing agent, particularly EDTA, which can be carried out in an extruder. The EDTA and the dissolved heavy metal can then be separated from the extruded melt. EDTA is a very slow-degrading compound. EDTA and the metals it complexes accumulate in water bodies when released. Therefore, there is ongoing discussion about limiting the industrial use of EDTA.

[0018] TASK OF INVENTION

[0019] The invention is based on the objective of demonstrating a method for removing lead from plastic, in particular PVC, which uses as few harmful chemicals as possible and yet can, on the one hand, safely reduce the lead content of PVC to a maximum of 0.1 wt.% and, on the other hand, recover the lead in a form suitable for recycling as metal or lead salt.

[0020] SOLUTION

[0021] The object of the invention is achieved by a method with the features of independent claim 1. The dependent claims relate to preferred embodiments of the method according to the invention. REHBERG HÜPPE + PARTNER - 3 - Originally filed version 22278 PCT 09.01.2026

[0022] DESCRIPTION OF THE INVENTION

[0023] In the process according to the invention, the plastic, in particular PVC, is presented to an alkali hydroxide solution, i.e., contacted with the alkali hydroxide solution, in order to extract the lead contained in the plastic as alkali plumbate dissolved in the alkali hydroxide solution. The lead is then deposited or precipitated as a metal or lead salt from the alkali hydroxide solution subsequently removed from the plastic.

[0024] The alkali hydroxide solution can contain sodium or potassium hydroxide. Preferably, it is a sodium hydroxide solution.

[0025] Surprisingly, it has been shown that phthalates and other substances soluble in the alkali hydroxide solution from plasticized PVC recyclates do not impede the process according to the invention. For example, no precipitation of lead phthalate was observed. The process according to the invention is therefore available for the removal or recovery of lead from plasticized PVC recyclates, such as cable recyclates, but also recyclates from roofing membranes and floor coverings. For reasons of durability, these PVC products often contain up to 5% by weight of lead, although its use in these applications has been prohibited for many years.

[0026] Stearates and other substances soluble in the alkali hydroxide solution from plasticizer-free PVC recyclates do not hinder the extraction and separation of lead. For example, no precipitation of lead erate was observed. The process according to the invention can therefore also be used to recover lead from PVC recyclates made of rigid PVC, such as window profiles and pipes.

[0027] The alkali hydroxide solution can be aqueous and have a pH value < 10. Preferably, the pH value of the alkali hydroxide solution is at least 12; thus, the alkali hydroxide solution is preferably strongly alkaline. However, adjusting the pH of the alkali hydroxide solution to a value greater than 14 is generally not necessary.

[0028] Instead of an aqueous solution, the alkali hydroxide solution can be a solution of sodium hydroxide in alcohol, in alcohol and water, or in alcohol and THF. However, the potential health and environmental impacts of THF must be considered. These potential impacts must also be taken into account when selecting the alcohol. This is REHBERG HÜPPE + PARTNER - 4 - Originally submitted version 22278PCT 09.01.2026

[0029] preferably with readily available and easy-to-handle ethanol. In the alcohol, or the alcohol and water, or the alcohol and THF, at least 8 wt%, and even more preferably at least 10 wt%, of alkali hydroxide is dissolved, based on the total weight.

[0030] In the process according to the invention, the separation of lead from the alkali hydroxide solution can be carried out easily without the use of ammonia by introducing carbon dioxide into the alkali hydroxide solution and / or adding alkali carbonate, such as soda ash, to the alkali hydroxide solution. The lead then precipitates as basic lead carbonate. No ammonia is required for this process. Although lead carbonate is toxic, it is a water-insoluble solid and therefore easy to handle safely.

[0031] Alternatively, the lead can be electroplated in metallic form directly from the alkali hydroxide solution in which the lead is dissolved as plumbate. This is presumably due to the low concentration of hydrogen cations in the alkali hydroxide solution.

[0032] To extract the lead from the plastic as completely as possible using the alkali hydroxide solution, the plastic typically needs to be in contact with the solution for at least 15 minutes. Often, it is preferable to contact the plastic with the alkali hydroxide solution for approximately 30 minutes. The required contact time to achieve a residual lead concentration of no more than 0.1 wt%—with the inventive method, residual lead concentrations in the range of 0.05 wt% down to 0.001 wt% are easily achievable—depends not only on the specific composition of the plastic but also on its relative surface area, i.e., the particle size and the resulting diffusion pathways. The relative amount of alkali hydroxide solution, whether the solution is applied countercurrently, as well as the pressure and temperature of the alkali hydroxide solution, also influence the optimal contact time between the plastic and the alkali hydroxide solution.A contact time of 45 minutes is generally sufficient, and it is not advisable to expose the plastic to the alkali hydroxide solution for more than 60 minutes to prevent alkali damage or unwanted dissolution. Furthermore, a limited process time is preferable from an economic standpoint.

[0033] The process according to the invention can be carried out at atmospheric pressure and at a temperature elevated above room temperature in a range of approximately 50 °C to 100 °C. REHBERG HÜPPE + PARTNER - 5 - Originally filed version 22278PCT 09.01.2026

[0034] In any case, the temperature should remain below the boiling point of the alkali hydroxide solution at the prevailing pressure. Preferably, the temperature remains between 5 K and 15 K, i.e., about 10 K, below this boiling point.

[0035] In another embodiment of the process according to the invention, the plastic is contacted with the alkali hydroxide solution under an increased pressure of at least 0.5 MPa, preferably at least 1.0 MPa. The increased pressure raises the boiling point and allows for an increased temperature of the liquid alkali hydroxide solution of, for example, at least 150 °C and preferably at least 160 °C, which accelerates the extraction of the lead with the alkali hydroxide solution. As a rule, however, the pressure used will not significantly exceed 100 MPa and the temperature will not significantly exceed the plasticizing temperature of the plastic, also because a significantly increased pressure and temperature of the alkali hydroxide solution would increase the complexity of the process according to the invention and the equipment required for its implementation.

[0036] In a specific embodiment of the inventive method, the plastic, in the form of particles, is contacted with the alkali hydroxide solution. The particles can have sizes ranging from 1.0 mm to 100 mm. This applies to all particle dimensions, although for ease of handling, the particles should ideally have approximately the same dimensions, preferably no more than 10 mm in all dimensions. Rod- or scale-shaped particles can also be processed. In the alkali hydroxide solution, the introduced particles can break down into smaller particles. However, care must be taken to ensure that no significant portions of the plastic dissolve. Therefore, the introduced particles preferably do not break down into particles smaller than 0.5 mm.When the plastic, in particle form, comes into contact with the alkali hydroxide solution, the extraction temperature should not reach the plasticizing temperature of the plastic to prevent clumping. Furthermore, when particles come into contact, the weight ratio of plastic to alkali hydroxide solution is typically between 1:0.05 and 1:0.25. Therefore, the dispersion of particles in the alkali hydroxide solution exhibits a relatively high particle loading.

[0037] In another specific embodiment of the process according to the invention, the plastic is plasticized in an extruder, and the alkali hydroxide solution is dispersed in the plasticized plastic to bring the plastic into contact with the alkali hydroxide solution. Typically REHBERG HÜPPE + PARTNER - 6 - Originally filed version 22278 PCT 09.01.2026

[0038] The plasticization of the plastic in the extruder takes place at an elevated temperature, at which the alkali hydroxide solution remains liquid only under increased pressure (see above). However, unlike the extraction of lead from particles, the temperature in the extruder will reach and may even exceed the plasticization temperature of the plastic. The high temperature in the extruder, combined with the short diffusion paths resulting from the dispersion of the alkali hydroxide solution, leads to a rapid mass transfer of the lead from the plastic into the alkali hydroxide solution, which can occur within a few seconds. Surprisingly, this applies to all lead compounds found in recycled PVC, such as lead oxide, lead sulfate, lead phosphate, and lead erate, which, despite their varying and low mobility, are transferred sufficiently quickly into the alkali hydroxide solution used as the extraction solvent.In this embodiment of the process according to the invention, the plastic can therefore be in contact with the alkali hydroxide solution for a significantly shorter time than 15 minutes, for example, for only 5 to 20 seconds or preferably from about 8 to 10 seconds. This contact duration falls within the range of typical residence times of the plastic in the extruder or a stage of the extruder in which, in this embodiment, the extraction of the lead from the plastic takes place.

[0039] In this embodiment of the inventive process, the plastic is contacted with the alkali hydroxide solution in a typically small weight ratio of 1:0.01 to 1:0.05. Thus, only a small amount of the alkali hydroxide solution, from 1 to 5 wt.%, is dispersed in the plastic.

[0040] The alkali hydroxide solution, containing dissolved alkali plumbate, is removed from the plastic in liquid form within the extruder. The plastic, however, can be shaped into a profile as it exits the extruder through a die, or cut into granules as it emerges from the die.

[0041] Due to the viscosity difference between the plasticized plastic and the alkali hydroxide solution, the specific energy input for adjusting the degree of dispersion of the alkali hydroxide solution within the plasticized plastic is crucial to enable rapid mass transfer into the alkali hydroxide solution. For this purpose, the insertion of pins into the extrusion cylinder, i.e., the use of a so-called pin extruder, and an axial movement of an extruder screw superimposed on the screw rotation have proven advantageous. REHBERG HÜPPE + PARTNER - 7 - Originally submitted version 22278 PCT 09.01.2026

[0042] Multi-screw extruders are particularly advantageous with regard to mass transport, especially for discharging the alkali hydroxide solution from the extraction zone. The use of an extruder cascade, e.g., consisting of a single-screw extruder with axial screw movement and a downstream multi-screw extruder as the extraction zone and pressure build-up zone for granulation on a perforated die, is also very advantageous with respect to the required concentration of alkali hydroxide solution as the extraction solvent and the achievable residual lead concentration in PVC.

[0043] Advantageous further developments of the invention result from the patent claims, the description and the drawings.

[0044] The advantages of features and combinations of features mentioned in the description are merely exemplary and can have an effect alternatively or cumulatively, without the advantages necessarily having to be achieved by embodiments according to the invention.

[0045] Regarding the disclosure content—not the scope of protection—of the original application documents and the patent, the following applies: Further features can be seen in the drawings—in particular, the relative arrangement and functional connection of several components. The combination of features from different embodiments of the invention or from features of different claims is also possible, deviating from the chosen cross-references in the claims, and is hereby encouraged. This also applies to features that are illustrated in separate drawings or mentioned in their description. These features can also be combined with features from different claims. Likewise, features listed in the claims can be omitted for further embodiments of the invention, but this does not apply to the independent claims of the granted patent.

[0046] The features mentioned in the patent claims and the description are to be understood, with regard to their number, as meaning that exactly that number or a greater number than the stated number is present, without the need for an explicit use of the adverb "at least". Thus, for example, when an extruder is mentioned, this is to be understood as meaning that REHBERG HÜPPE + PARTNER - 8 - Originally filed version 22278PCT 09.01.2026

[0047] Exactly one extruder, two extruders, or more extruders are present. The features listed in the patent claims may be supplemented by further features or may be the only features that the subject matter of the respective patent claim possesses.

[0048] The reference numerals contained in the patent claims do not constitute a limitation of the scope of the subject matter protected by the patent claims. They merely serve the purpose of making the patent claims easier to understand.

[0049] BRIEF DESCRIPTION OF THE FIGURES

[0050] The invention will now be further explained and described with reference to preferred embodiments shown in the figures.

[0051] Fig. 1 is a flowchart for carrying out a first embodiment of the method according to the invention and

[0052] Fig. 2 is a flowchart for carrying out a second embodiment of the method according to the invention.

[0053] FIGURE DESCRIPTION

[0054] Fig. 1 illustrates the process of a first embodiment of the inventive method for removing lead from plastic in the form of a flowchart, which is also a simplified block diagram of a system for carrying out the inventive method. Particles 3 made of plastic 4, in particular PVC 5, and an alkali hydroxide solution 6 are placed in a stirred tank 1 equipped with an agitator 2. In the stirred tank 1, the particles 3 are dispersed in the alkali hydroxide solution 6, which serves as the extraction agent 7, and stirred by the agitator 2. This is done at elevated temperature and optionally elevated pressure to prevent the extraction agent 7 from boiling. Through contact between the plastic 4 and the alkali hydroxide solution 6 as the extraction agent 7, lead is extracted from the plastic 4 and dissolved as alkali plumbate in the alkali hydroxide solution 6.

[0055] In a separation device 8, the alkali hydroxide solution 6 with the dissolved alkali plumbate 9 is separated from the plastic particles 4, which now only have a residual concentration of REHBERG HÜPPE + PARTNER - 9 - Originally submitted version 22278PCT 09.01.2026

[0056] less than 0.1 wt% lead. In a precipitation device 10, carbon dioxide 11 is blown into the alkali hydroxide solution 6 containing the dissolved alkali plumbate 9 and dispersed. The precipitation device 10 may also include an agitator for this purpose. In the precipitation device 10, the lead precipitates from the alkali hydroxide solution 6 as insoluble lead carbonate 12 and can thus be removed separately from the alkali hydroxide solution 6 directly from the precipitation device 10 or using a further separation device. The lead carbonate 12, as well as the plastic particles 3 4 with a residual lead concentration of less than 0.1 wt%, are suitable for recycling.

[0057] Instead of the drop device 10, a separation device for the electroplating of metallic lead directly from the alkali hydroxide solution 6 could be provided. The lead would then be available in metallic form for recycling.

[0058] The embodiment of the process according to the invention, illustrated in a flowchart in Fig. 2, where the flowchart is also a block diagram of a system suitable for carrying out the process, is largely carried out in an extruder 13, which in this case is an extruder cascade 14. The extruder cascade 14 has an inlet-side single-screw extruder 15 with an extruder screw 16 that is driven both rotaryally and in a reciprocating axial motion. In the single-screw extruder 15, the thermoplastic material 4, introduced in the form of particles 3, is plasticized. Downstream of the single-screw extruder 15, the extruder cascade 14 has a multi-screw extruder 16 in which the alkali hydroxide solution 6, serving as the extraction agent 7, is added to the plasticized material 4 and dispersed therein.The extraction of lead from the plastic 4 in the multi-screw extruder 16 takes place at a pressure typically increased to at least 1 MPa and at a temperature typically increased to at least 150 °C. Upon fine dispersion of the liquid alkali hydroxide solution 6 in the plasticized plastic 4, a rapid mass transfer of the lead from the plastic 4 into the extraction solvent 7 occurs. This solvent, along with the dissolved alkali plumbate 9, is then discharged into the precipitation unit 10. The plastic 4, without the alkali hydroxide solution 6 and with a residual lead concentration reduced to less than 0.1 wt%, exits the multi-screw extruder 16 in strands through a perforated plate 17. These strands are then cut into granules 19 by a rotating blade 18.In the case device 10, the alkali hydroxide solution 6 with the alkali plumbate 9 dissolved therein is used here alternatively or additionally to REHBERG HÜPPE + PARTNER - 10 - Originally submitted version 22278PCT 09.01.2026.

[0059] to the carbon dioxide 11 alkali carbonate 20, for example soda, in order to precipitate the lead as lead carbonate 12.

[0060] Here too, instead of the failure device 10, a separation device for the electroplating of metallic lead from the alkali hydroxide solution 6 can be used.

[0061] The following embodiments 1 to 5 of the process according to the invention can be implemented in the embodiment shown in Fig. 1, wherein normal pressure prevails during the extraction for approximately 30 minutes and the temperature of the alkali hydroxide solution remains 10 K below its respective boiling point. A residual lead concentration in the range of 0.001 wt.% to 0.05 wt.% is achieved. The further embodiments 6 to 8 of the process according to the invention can be implemented in the embodiment shown in Fig. 2, wherein the alkali hydroxide solution 6 is in contact with the plastic 4 in the extruder 13 for only about 8 to 10 seconds.

[0062] Example 1

[0063] PVC recyclate: Cable fraction. Reaction medium / extraction solvent: Aqueous sodium hydroxide solution (pH > 13). Extraction technique: Stirred tank reactor.

[0064] Precipitating agent: Carbon dioxide

[0065] Product: PbCO3

[0066] Example 2

[0067] PVC recyclate: Recyclate from PVC roofing membranes. Reaction medium / extraction agent: saturated potassium hydroxide solution in ethanol / THF mixture (1:2)

[0068] Extraction technique: Stirred tank

[0069] Precipitating agent: Soda

[0070] Product: PbCO3

[0071] Example 3

[0072] PVC recyclate: Recyclate from PVC roofing membranes. Reaction medium / extraction agent: saturated sodium hydroxide solution in water / THF mixture (1:1). REHBERG HÜPPE + PARTNER - 11 - Originally submitted version 22278PCT 09.01.2026

[0073] Extraction technique: Stirred tank

[0074] Precipitating agent: Soda

[0075] Product: PbCO3

[0076] Example 4

[0077] PVC recyclate: Recyclate from PVC window profiles. Reaction medium / extraction agent: saturated sodium hydroxide solution in ethanol / THF (1:2)

[0078] Extraction technique: Stirred tank

[0079] Electroplating: Voltage > 0.125 V,

[0080] Current density of 0.05 - 0.12 A / cm² 2

[0081] Product: Pb

[0082] Example 5

[0083] PVC recyclate: Recyclate from PVC flooring. Reaction medium / extraction agent: aqueous sodium hydroxide solution (0.5 wt%). Extraction technique: counter-rotating twin-screw extruder. Precipitating agent: soda.

[0084] Product: PbCO3

[0085] Example 6

[0086] PVC recyclate: PVC from pipe waste with 5.5 wt% lead. Reaction medium / extraction agent: 70 wt% water, 20 wt% ethanol, 10 wt%

[0087] Sodium hydroxide

[0088] Extraction technology: Cascade consisting of a single-screw pin extruder and a subsequent single-screw extruder for extraction

[0089] Temperature: 175 °C in the extraction area

[0090] Discharge pressure: 10 bar in the extraction area. Residual concentration: < 0.1 wt% lead (measured by X-ray fluorescence spectroscopy).

[0091] Precipitating agent: Soda

[0092] Product: PbCO3REHBERG HÜPPE + PARTNER - 12 - Originally submitted version 22278PCT 09.01.2026

[0093] Example 7

[0094] PVC recyclate: PVC from edgebanding with 6 wt% lead. Reaction medium / extraction agent: 90% water, 10% sodium hydroxide. Extraction technology: Cascade consisting of a co-rotating twin-screw extruder and a downstream single-screw extruder for extraction. Temperature: 185 °C in the extraction zone.

[0095] Discharge pressure: 25 bar in the extraction area. Residual concentration: < 0.1 wt% lead (measured by X-ray fluorescence spectroscopy).

[0096] Precipitating agent: Soda

[0097] Product: PbCO3

[0098] Example 8

[0099] PVC recyclate: PVC from cable duct with 5.0 wt% lead. Reaction medium / extraction solvent: 50% ethanol, 50% sodium hydroxide solution (10%). Extraction technology: co-rotating twin-screw extruder and subsequent melt pump.

[0100] Temperature: 170 °C in the extraction area

[0101] Discharge pressure: 17 bar in the extraction area.

[0102] Residual concentration: < 0.1 wt% lead (measured by X-ray fluorescence spectroscopy)

[0103] Electroplating: Voltage > 0.125 V

[0104] Current density of 0.05 - 0.12 A / cm2

[0105] Product: PbREHBERG HÜPPE + PARTNER - 13 - Originally submitted version 22278PCT 09.01.2026

[0106] REFERENCE MARK LIST

[0107] 1 mixing bowl

[0108] 2 agitator

[0109] 3 particles

[0110] 4 plastic

[0111] 5 PVC

[0112] 6 Alkali hydroxide solution

[0113] 7 Extraction solvents

[0114] 8 Separating device

[0115] 9 Alkali plumbate

[0116] 10 failover device

[0117] 11 Carbon dioxide

[0118] 12 Lead carbonate

[0119] 13 extruders

[0120] 14 Extruder cascade

[0121] 15 single-screw extruders

[0122] 16 multi-screw extruders

[0123] 17 perforated plate

[0124] 18 rotating knives

[0125] 19 granules

[0126] 20 Alkali carbonate

Claims

REHBERG HÜPPE + PARTNER - 14 - Originally submitted version 22278PCT 09.01.2026 PATENT CLAIMS 1. Method for removing lead from plastic (4) comprising the steps Contacting the plastic (4) with an alkali hydroxide solution (6) to extract lead contained in the plastic (4) as alkali plumbate (9) dissolved in the alkali hydroxide solution (6), removing the alkali hydroxide solution (6) with the alkali plumbate (9) dissolved therein from the plastic (4) and Separation of the lead from the removed alkali hydroxide solution (6).

2. The method of claim 1, wherein the alkali hydroxide solution (6) comprises sodium and / or potassium hydroxide and is optionally a sodium hydroxide solution.

3. Method according to claim 1 or 2, wherein the alkali hydroxide solution (6) is an aqueous solution with a pH value > 10, preferably a pH value between 12 and 14.

4. Method according to claim 1 or 2, wherein the alkali hydroxide solution (6) is a solution of sodium hydroxide in alcohol or in alcohol and water or in alcohol and THF, wherein the alkali hydroxide solution (6) optionally contains at least 8 wt%, preferably at least 10 wt% sodium hydroxide.

5. Method according to any one of the preceding claims, wherein the deposition of the lead from the alkali hydroxide solution (6) without the use of ammonia and / or by introducing carbon dioxide (11) and / or with the addition of alkali carbonate (20) and / or galvanic This has been done.

6. A method according to any of the preceding claims, wherein the plastic (4) is contacted with the alkali hydroxide solution (6) under a pressure of at least 0.5 MPa, preferably at least 1.0 MPa, and at most 100 MPa, and a temperature of at least 150 °C, preferably at least 160 °C, and at most 220 °C. REHBERG HÜPPE + PARTNER - 15 - Originally filed version 22278 PCT 09.01.2026 7. Method according to one of the preceding claims, wherein the plastic (4) in the form of particles (3) is contacted with the alkali hydroxide solution (6), wherein the particles (3) have particle sizes in the range of 1.0 mm to 100 mm, wherein the plastic (4) is optionally contacted with the alkali hydroxide solution (6) in a weight ratio of 1:0.05 to 1:0.

25.

8. Method according to one of the preceding claims, wherein the plastic (4) is contacted with the alkali hydroxide solution (6) for at least 15 minutes and at most 60 minutes, preferably at most 45 minutes.

9. Method according to any one of claims 1 to 6, wherein the plastic (4) is plasticized in an extruder and the alkali hydroxide solution (6) is dispersed in the plasticized plastic (4) to contact the plastic (4) with the alkali hydroxide solution (6), wherein the plastic (4) is optionally contacted with the alkali hydroxide solution (6) in a weight ratio of 1:0.01 to 1:0.

05.

10. Method according to one of the preceding claims, wherein the plastic (4) is contacted with the alkali hydroxide solution (6) for 5 seconds to 20 seconds, preferably for 8 seconds to 10 seconds.

11. Method according to claim 9 or 10, wherein the alkali hydroxide solution (6) with the alkali plumbate (9) dissolved therein is removed from the plastic (4) in the extruder (13) and wherein the plastic (4) is formed into a profile or cut into granules (19) as it exits the extruder (13) through a perforated disc (17).

12. Method according to claim 9, 10 or 11, wherein the extruder (13): a single-screw extruder (15) and / or a pen extruder and / or a multi-screw extruder (16) and / or an extruder cascade (14) and / or a rotary and axially movable extruder screw (16) exhibits.

13. A method according to any of the preceding claims, wherein the plastic (4) is a PVC (5) and optionally a recycled PVC. REHBERG HÜPPE + PARTNER - 16 - Originally filed version 22278 PCT 09.01.2026 14. Method according to any of the preceding claims, wherein the plastic (4) contains plasticizers and optionally originates from cable sheaths and / or roofing membranes and / or floor coverings.

15. Method according to one of the preceding claims, wherein the plastic (4) is plasticizer-free and optionally originates from plastic window profiles and / or plastic tubes.

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