Method for separating different polymeric spectacle lens materials in a mixture

Abstract

The invention provides a method 100 for separating different polymeric spectacle lens materials in a mixture comprising at least two different polymeric spectacle lens materials by separating at least one polymeric spectacle lens material of the at least two different polymeric spectacle lens materials by using their different physical behavior and / or chemical behavior, wherein the at least two different polymeric spectacle lens materials are selected from the group consisting of polyallyl carbonate, polyurea, polyurethane, polyurethane / polyurea, polycarbonate, polyepisulfide and polythiourethane. The invention further provides a method for separating at least one polythiourethane from a mixture comprising at least two different polythiourethanes by thiolysis.

Description

[0001] Method for separating different polymeric spectacle lens materials in a mixture

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method for separating different polymeric spectacle lens materials in a mixture comprising at least two different polymeric spectacle lens materials. The present invention further relates to a method for separating at least one polythiourethane from a mixture comprising at least two different polythiourethanes.

[0004] BACKGROUND ART

[0005] A wide variety of plastic materials are used in the optical industry today, particularly in the manufacture of spectacle lenses. Most of these are network polymers, more precisely duromers, and the others are thermoplastic materials. Typical network polymers are polyallyl carbonates such as polyallyl diglycol carbonates (PADC), polyurethanes (PUR), polyurethanes / polyureas (PUR / PUA), polythiourethanes (PTU) and polyepisulfides. Typical thermoplastic materials are polycarbonates and polyamides. The table shown in Fig. 2 lists typical materials and their optical properties.

[0006] During the production of the final optical articles, various types of mixed material waste are produced at different points in the manufacturing process, which are nowadays mainly incinerated or sent to landfill. This waste occurs in different qualities and quantities. This mainly includes scrap lenses, lens fragments as well as milling and grinding waste. The above-mentioned types of disposals have a negative impact both ecologically and economically.

[0007] The above-mentioned materials are resistant to environmental influences and thus contribute to the accumulation of such materials, including microplastics, in the environment, while incineration releases the carbon stored in the materials into the atmosphere as the greenhouse gas CO2. This also increases the GWP (global warming potential) of these products. Finally, potentially valuable resources are lost through the incineration or disposal of these waste streams. The endeavor to recycle this waste and using it to create value is therefore obvious and desirable and contributes to a functioning circular economy.

[0008] The state of the art describes various recycling processes of the above-mentioned materials, whereby a distinction should be made between thermoplastics and network polymers.

[0009] Thermoplastics, such as the typical bisphenol A-based polycarbonate, are soluble under appropriate conditions, but can also be melted and processed into new products. The recovery of polycarbonates by solvent-based, selective dissolution and subsequent precipitation with good purities and the preservation of polymer properties is described, for example, in WEEDEN, G.S. et. Al. Method for Efficient Recovery of High-Purity Polycarbonates from Electronic Waste. Environ. Sci. Technol., 2015, 49, 4, pages 2425- 2433 or ACHILIAS, D.S. et al. Chemical Recycling of Polymers from Waste Electric and Electronic Equipment. J. Appl. Polym. Sci. 2009, 114, pages 212-221.

[0010] Network polymers are insoluble and cannot be melted. Therefore, in addition to their use as fillers or for thermal utilization, chemical recycling processes are the main option for this polymer class. Chemical recycling methods are known for pure or slightly contaminated network polymers to recover monomers or polymerizable degradation products from the network polymers.

[0011] For example, US 2023 / 0 365 770 A1, describes a process that converts a polythiourethanes material, e.g., milling / grinding waste, into a polymerizable polythiol mixture by means of alcoholysis or aminolysis resulting in depolymerization. Hybrid materials made of polythiourethane, and other polymers are also mentioned, however the mass fraction of polythiourethanes should preferably be at least 80%, more preferably at least 90%.

[0012] Furthermore, HUANG, S. et al. Chemical recycling of poly(thiourethane) thermosets enabled by dynamic thiourethane bonds. Polym. Chem., 2020, 11, pages 6879-6883 describes the depolymerization of a polythiourethane material by means of basecatalyzed thiolysis to form repolymerizable oligomeric polythiols. The applicability to polythiourethanes other than the structures used and the applicability to material mixtures are not addressed.

[0013] JOHANSEN, M.B. et al. tert-Amyl Alcohol-Mediated Deconstruction of Polyurethane for Polyol and Aniline Recovery. ACS Sustainable Chem. Eng, 2022, 10, 34, pages 11191- 11202 describes the alcoholysis of various polyurethane materials and the recovery of polyols and polyamines as depolymerization products. US 6 489 373 B2 discloses a method of recovering a polyamine compound and / or a polyol compound useful for the starting materials of polyurethane resin in an industrially advantageous manner by chemically decomposing scraps generated in the process of fabricating polyurethane resin products, or from waste generated after the use of the polyurethane products. However, in both publications only pure substances and, in the case of US 6489 373 B2, at least no non-polyurethanes are processed.

[0014] Publications on depolymerization for polyallyl diglycol carbonates are not known. However, there are other publications that deal with the depolymerization of other polycarbonates. Due to the structural similarity regarding the carbonate group, these other publications might nevertheless be relevant. For example, WO 2022 / 218 914 A1 describes the aminolysis and alcoholysis of bisphenol A-based polycarbonate. Similar alcoholysis processes are disclosed in QUARANTA, E. et al. Depolymerization of poly(bisphenol A carbonate) under mild conditions by solvent-free alcoholysis catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene as a recyclable organocatalyst: a route to chemical recycling of waste polycarbonate. Green Chem, 2017, 19, pages 5422-5434 and US 2023 / 0 383 089 A1. However, both publications only describe the recycling of pure substances.

[0015] Thus, according to the state of the art, there are no chemical recycling techniques for material flows comprising a mixture of polymeric materials as mentioned in the beginning and listed in table 1 , in particular if milling and grinding residues occur as the material mixture or waste. Furthermore, according to the state of the art, there are no methods for separating typical and, for example, mixed grinding and milling waste from the optical industry into its single components. Such waste therefore represents a waste stream that can neither be used as a mixture nor separated into its components.

[0016] WO 20231276 975 A1 , which represents the closest state of the art, provides a resin scrap management method that can manage resin scrap in a manner that makes it easy to determine the treatment, e.g. disposal or recycling, that should be applied to the resin scrap by use of databases, and a resin scrap recovery method that can recover the resin scrap managed by this management method. The waste to be treated should comprise a main component of at least 50 %, preferably at least 60 % or even better at least 80 %. Preferably, the resin scraps contain at least one selected from the group consisting of a polythiourethane resin, an episulfide resin, a polycarbonate resin, a poly(meth)acrylate resin, and an allyl diglycidyl carbonate resin. Other components such as additives for resins, water, oil, abrasives, surfactants, acids, alkalis, and the like may be present. If recycling is recommended, a further database can be used to determine the chemical decomposition method for the resin waste.

[0017] WO 20231276 975 A1 describes a method that will only consider waste streams with sufficient purity for chemical recycling. Mixed waste, such as that typically produced in the manufacture of spectacle lenses, however, often contains significantly less than 50 % of a single component leading to non-recycling according to the described method. Thus, according to the prior art, it is only possible to recycle pure substances or mixtures of substances with very limited mixing ratios.

[0018] SUMMARY OF THE INVENTION

[0019] With respect to the mentioned state of the art, it is an objective of the present invention to provide an improved method for separating different polymeric spectacle lens materials in a mixture comprising at least two different polymeric spectacle lens materials, which allows for better recycling and reuse of the materials. It would be desirable to process typical material mixtures such as mixtures without a main component, i.e. , each component having a mass fraction of less than 50 %, in various forms and to generate valuable products as a result.

[0020] The objective is achieved by a method for separating different polymeric spectacle lens materials in a mixture comprising at least two different polymeric spectacle lens materials as claimed in claim 1 and a method for separating at least one polythiourethane material from a mixture as claimed in claim 15.

[0021] Throughout this specification the following definitions apply:

[0022] The term “alcohol” typically refers to an organic compound that carries at least one hydroxy (-OH) functional group bound to a saturated carbon atom, e. g. R3COH. Phenols are compounds having at least one hydroxy functional group where the hydroxy group is attached to a benzene ring or other arene ring. In the following, the term alcohol refers to alcohols in the typical sense and phenols alike.

[0023] The term “alcoholysis” refers to a solvolysis, i.e., a reaction with a solvent, or with a lyonium ion or lyate ion involving the rupture of one or more bonds in the reacting solute, wherein the solvent is an alcohol ('solvolysis' in IUPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1 , 2019. https: / / doi.org / 10.1351 / goldbook.S05762) and wherein the solute can be a solid or a liquid.

[0024] The term “aliphatic” refers to an acyclic or cyclic, saturated, or unsaturated carbon compound, excluding aromatic compounds ('aliphatic compounds' in IUPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1 , 2019. https: / / doi.org / 10.1351 / goldbook.A00217).

[0025] The term “aprotic solvent” refers to a solvent without an acidic proton. Such solvents lack hydroxyl and amine groups and are typically aliphatic or aromatic hydrocarbons containing at least one heteroatom such as oxygen, nitrogen, or sulfur.

[0026] The term “chemical behavior” refers to the behavior of a material or substance due to its chemical properties, e.g., its chemical reactivity, upon a certain chemical condition, such as added reactant.

[0027] The term ’’chemical reactivity” refers to the ability of a chemical substance, e.g., a material contained in the waste, to interact chemically or to undergo a chemical reaction with another chemical substance. The term expresses a kinetic property. A species is said to be more reactive or to have a higher reactivity in some given context than some other (reference) species if it has a larger rate constant for a specified elementary reaction ('reactive (reactivity)' in IUPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1 , 2019. https: / / doi.Org / 10.1351 / goldbook. R05180).

[0028] The term “drying” refers to a process of removing liquids, especially water, from a substance, composition, or object, e.g., the mixture comprising different polymeric spectacle lens materials, by evaporation, vaporization, the use of drying agents, or other technical and chemical applications. Drying is therefore characterized by the reduction of moisture through a generally thermal-physical transformation of the liquid to be removed, usually a phase transformation into the gaseous state.

[0029] The term “glycol" refers to dihydric alcohols (diols) in which the two hydroxy groups are on different carbon atoms, usually but not necessarily adjacent ('glycols' in IUPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1 , 2019. https: / / doi.org / 10.1351 / goldbook.G02654).

[0030] The term “hydrocarbon” refers to a compound consisting of carbon and hydrogen only ('hydrocarbons' in IIIPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1, 2019. https: / / doi.org / 10.1351 / goldbook.H02889). The term “chlorinated hydrocarbon” refers to a compound consisting of carbon, hydrogen, and chlorine only.

[0031] The term “lysis product” refers to the reaction product obtained by depolymerization, i.e. , the depolymerized phase or a component of the depolymerized phase. Depolymerization can, for example, be achieved by thiolysis and / or alcoholysis.

[0032] The term ’’material" refers to a substance or mixture of substances that constitutes an object, e.g., the waste.

[0033] The term “physical behavior” refers to the behavior of a material or substance due to its physical properties, e.g., melting point, boiling point, solubility, density, upon a certain physical condition, such as temperature, pressure, added solvent.

[0034] The term “polar solvent” refers to a solvent with polar molecules, i.e., molecules having a net dipole as a result of opposing charges from polar bonds arranged asymmetrically.

[0035] The term “polyacrylate” refers to a polymer manufactured by polymerization of an acrylate monomer, i.e., esters of acrylic acid.

[0036] The term “polyallyl carbonate” refers to a thermoset, i.e., crosslinked, polymer manufactured by polymerization of allyl carbonate monomers. Specifically, the term “polyallyl diglycol carbonate” (PADC, CAS 25656-90-0) refers to a polymer manufactured by polymerization of allyl diglycol carbonate monomers, such as CR39.

[0037] The term “polycarbonate” (PC) refers to a group of thermoplastic polymers containing carbonate groups -O-(C=O)-O- in their chemical structures. Specifically, the term “polycarbonate” may refer to polycarbonates based on bisphenols, such as bisphenol A.

[0038] The term “polyepisulfide” refers to a group of polymers manufactured by polymerization of monomers that contain at least one episulfide group.

[0039] The term “polyisocyanate” refers to a class of compounds that contain two or more isocyanate groups -NCO in their structure.

[0040] The terms "polymer" and "polymeric" refer to natural or synthetic substances composed of macromolecules composed of many repeating subunits. They comprise homopolymers and copolymers.

[0041] The term “polymeric material” as used herein encompasses different polymers of a particular class of material, e.g., the material polythiourethane may consist of a number of chemically distinct polythiourethanes.

[0042] The term “polyol” refers to a class of compounds that contain two or more alcohol groups or hydroxy groups -OH in their structure.

[0043] The term “polythiol” refers to a class of compounds that contain two or more thiol groups -SH in their structure. In contrast, a “monothiol” only contains a single thiol group.

[0044] The term “polythiourethane” (PTU) refers to a class of polymers composed of organic units joined by thiourethane links -S-(C=O)-(NH)-. A polythiourethane is typically produced by reacting a polyisocyanate with a polythiol.

[0045] The term “polyurea” (PUA) refers to a polymer that is derived from the reaction product of an isocyanate component and an amine component and / or a class of polymers composed of organic units joined by urea links -(NH)-(C=O)-(NH)-.

[0046] The term “polyurethane” (PUR) refers to a class of polymers composed of organic units joined by carbamate (urethane) links -O-(C=O)-(NH)-. A polyurethane is typically produced by reacting a polyisocyanate with a polyol.

[0047] The term “shredding” refers to a process for reducing the size of a material or object by physical interaction such as cutting, grinding, milling, shredding etc.

[0048] The term "spectacle lens" refers to an ophthalmic lens worn in front of, but not in contact with, the eyeball (ISO 13666:2019(E), section 3.5.2), where an ophthalmic lens is a lens intended to be used for purposes of measurement, correction and / or protection of the eye, or for changing its appearance (ISO 13666:2019(E), section 3.5.1).

[0049] The term “spectacle lens material” refers to a material that is used for manufacturing of a spectacle lens, e.g., the material of the spectacle lens substrate. The term "spectacle lens substrate" refers to a piece of optical material that is used during the manufacturing process of a spectacle lens, i.e. precursors of a finished lens (ISO 13666:2019(E), section 3.8.7), an uncut lens (ISO 13666:2019(E), section 3.8.8) or an edged lens (ISO 13666:2019(E), section 3.8.9). Suitable precursors of the finished lens are for example semi-finished lens blanks, wherein the term "semi-finished lens blank" refers to a piece of optical material with one optically finished surface for the making of a spectacle lens (ISO 13666:2019(E), section 3.8.1).

[0050] The term “strong basic catalyst” refers to organic catalysts featuring a pka (in acetonitrile) of the conjugate acid of 10 or higher wherein pka is the negative base-10 logarithm of the acid dissociation constant Ka of the solution (in acetonitrile).

[0051] The term "substance" refers to a chemical substance which is a form of matter having a constant chemical composition and which is best characterized by the entities (molecules, formula units, atoms) it is composed of. Physical properties such as density, refractive index, electric conductivity, melting point etc. characterize the chemical substance by characteristic properties ('chemical substance' in IIIPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1 , 2019. https: / / doi.org / 10.1351 / goldbook.C01039).

[0052] The term “thiol” refers to an organosulfur compound that carries at least one thiol functional group -SH bound to a saturated carbon atom, e.g., R3CSH, where R represents an alkyl or other organic substituent. Thiophenols are compounds having at least one thiol functional group where the thiol group is attached to a benzene ring or other arene ring. In the following, the term thiol refers to thiols in the typical sense and thiophenols alike. Thiols are sulfur analogues of alcohols, i.e., sulfur takes the place of oxygen in the hydroxyl group of an alcohol.

[0053] The term “thiol-ene reaction” refers to a chemical reaction between a thiol R-SH and an alkene R2C=CR2 to form a thioether R-S-R'.

[0054] The term “thiolysis” refers to a solvolysis, i.e., a reaction with a solvent, or with a lyonium ion or lyate ion involving the rupture of one or more bonds in the reacting solute, wherein the solvent is a thiol ('solvolysis' in IUPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1 , 2019. https: / / doi.org / 10.1351 / goldbook.S05762) and wherein the solute can be a solid or a liquid.

[0055] The term “temperature control” refers to running a chemical reaction, such as thiolysis, at a specified reaction temperature or by applying a specified temperature profile.

[0056] The term “time control” refers to running a chemical reaction, such as thiolysis, for a specified period of time. After expiry of this time period, the reaction is stopped and already reacted material, e.g., depolymerized material, can be separated from materials un-reacted.

[0057] The term “waste” refers to materials, substances, or by-products to be eliminated or discarded as no longer useful or required. Waste from the manufacture of polymeric spectacle lenses may include scrap lenses and manufacturing residues such as grinding and milling residues. Waste of polymeric spectacle lenses may include spectacle lenses no longer needed, for example due to damage or altered ophthalmic diseases.

[0058] The articles "a", "an", and "the" as used in this specification and the appended claims include plural referents unless expressly and unequivocally limited to one referent.

[0059] The term "and / or" as used herein, when used in a series of two or more elements, means that any of the listed elements may be used alone, or any combination of two or more of the listed elements may be used. For example, when describing the usage of methods A, B, and / or C, method A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination may be used.

[0060] The term ..comprising" means various compositions, compounds, steps and the like can be conjointly employed in the present invention. Accordingly, the term “comprising” encompasses the more restrictive terms “consisting essentially of” and “consisting of”. The terms “comprising” and “containing” may be used synonymously.

[0061] A basic idea of the invention is to enable the value-adding use or recycling of mixed plastic waste, including grinding and milling waste as well as swarf from the optical industry, especially the manufacturing of polymeric spectacle lenses. This is achieved by exploiting the different behavior towards different chemical environments of the polymers present in the mixed waste. For example, concepts known from the literature, such as thiolysis and alcoholysis, are optimized and combined. As a result, the substance classes present in the mixture can be selectively extracted one after the other. In a first aspect, the invention provides a method for separating different polymeric spectacle lens materials in a mixture comprising at least two different polymeric spectacle lens materials.

[0062] In a specific development, the method may be used for separating polymeric materials contained in waste of polymeric spectacle lenses and / or waste from the manufacture of polymeric spectacle lenses. The at least two different polymeric spectacle lens materials are selected from the group consisting of polyallyl carbonate, such as polyallyl diglycol carbonate, polyurea, polyurethane, polyurethane / polyurea, polycarbonate, polyepisulfide and polythiourethane.

[0063] It is suggested that at least one polymeric spectacle lens material of the at least two different polymeric spectacle lens materials is separated by using the different physical behavior, i.e. , different physical properties such as solubility in a certain solvent, e.g., an alcohol such as glycol, or the density, and / or chemical behavior of the polymeric materials. Separating at least one polymeric material of the at least two polymeric materials means that any number, e.g., one, two or all, polymeric materials comprised in the mixture can be separated. For example, as the material polythiourethane may comprise a number of chemically distinct polythiourethanes, all these chemically distinct polythiourethanes may be separated from the other materials in the mixture, i.e., at least two polymeric material classes are separated from each other.

[0064] The group of polymers contained in the mixture to be treated is not particularly limited, i.e., the mixture may comprise further polymers apart from the above-mentioned polymers such as polyacrylates or polyethylene terephthalates. Further examples of other polymers are: a polyolefin film that protects the surface of a spectacle lens substrate for spectacle lens production, a hard coat or a primer coat that protects the surface of a spectacle lens substrate and / or spectacle lens, an abrasive agent used for grinding a spectacle lens substrate for spectacle lens production, a tape or tape glue that is used for immobilizing the glass mold used in the preparation of a spectacle lens substrate for spectacle lens production.

[0065] The mixture or waste to be treated may in addition contain at least one additional material or substance selected from the group consisting of a polymerization catalyst, a metal, a UV absorber, an internal mold release agent, a plasticizer, a dye, a machine oil, and water.

[0066] The proposed method is particularly suitable for waste containing polythiourethane and at least one of polyallyl carbonate, such as polyallyl diglycol carbonate, polyurea, polyurethane or polyurethane / polyurea. Additionally, polycarbonate may be present.

[0067] The present invention provides a method for separating mixed polymers of polymeric spectacle lens materials, for example polymers contained in polymer waste, into certain compound groups or their lysis products or for enriching certain compound groups to process them elsewhere, for example, where processing without prior enrichment was not feasible or profitable. The lysis products obtained can be used in a valuable way to produce downstream products. The same applies to the use of the separated polycarbonates, if any. Separated polycarbonate can also be converted into new products, for example as a 100% recycled material, in combination with non-recycled materials or as composite materials. This invention thus closes a gap on the road to a circular economy.

[0068] The proposed method enables the recycling of mixed polymers of various forms and compositions. For example, mixtures without a main component, i.e., a component with a mass fraction of at least 50 % of the mixture, or, in other words, mixtures wherein each component of the mixture has a mass fraction of less than 50 % can be processed. Especially, mixed waste from the optical industry can be recycled and is not disposed of as waste. If the waste is reused, the waste disposal process step can be eliminated. As the mixed waste is the largest mass compared to separated waste, there is great potential for savings through reduced disposal costs and the production of valuable recycled products.

[0069] In a specific development of the inventive method, the method may comprise at least two steps selected from the group consisting of a physical dissolution step, a thiolysis step, and an alcoholysis step.

[0070] Preferably, the physical dissolution step can be carried out before, e.g., directly before, the thiolysis step and / or the alcoholysis step, i.e., if the method comprises a thiolysis step but no alcoholysis step, the physical dissolution step is carried out before the thiolysis step; if the method comprises an alcoholysis step but no thiolysis step, the physical dissolution step is carried out before the alcoholysis step; if the method comprises both a thiolysis step and an alcoholysis step, the physical dissolution step is carried out once before both lysis steps.

[0071] Preferably, the thiolysis step can be carried out before, e.g., directly before, the alcoholysis step.

[0072] Within the thiolysis step, a polymeric compound contained in the mixture to be treated is cleaved by adding at least one thiol. Using thiolysis, polythiourethane materials, which are not physically soluble due to their network structure, can be chemically depolymerized and separated. By using different thiolysis conditions, it is possible to separate polythiourethane materials into subgroups exhibiting a different affinity to depolymerization under the given thiolysis conditions.

[0073] For performing thiolysis, the waste or remaining residue obtained from previous treatment steps may be mixed with a solvent or mixture of solvents, i.e. , thiolysis can be carried out with or without a solvent. Further, a thiolysis reagent is added. Moreover, a catalyst for promoting thiolysis can be added. The mixture is stirred at a certain temperature, e.g., a temperature within the range from 20 °C to 100 °C, preferably from 50 °C to 65 °C, for a certain time, e.g., a time period within the range from 30 minutes to 7 days, preferably 30 minutes to 8 hours, with the aim of depolymerizing polythiourethanes, preferably at least to such an extent that polythiourethanes are completely dissolved and can consequently be separated from the remaining solid substances in a downstream filtration step.

[0074] Possible catalysts for promoting thiolysis are basic organic catalysts, such as but not limited to catalysts that are also suitable for transesterifications. Suitable basic organic catalysts may feature a pka (in acetonitrile) of the conjugate acid of 10 or higher such as but not limited to triazabicyclodecanes like 1 ,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) or 7- methyl-1,5,7-triazabicyclo(4.4.0)dec-5-ene, diazabicycloundecenes like 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU), 1 ,1 ,3,3-tetramethylguanidine, 1,5- diazabicyclo[4.3.0]non-5-ene, 1 ,4-diazabicyclo[2.2.2]octane, 1 ,4- diazabicyclo[2.2.2]octane, or 2,2,6,6-tetramethylpiperidin. Triazabicyclodecenes such as TBD (CAS: 5807-14-7) are preferred due their suiting combination of basicity and limited nucleophilicity, thus, increasing thiolysis efficiency while preventing side reactions.

[0075] Possible solvents may be organic polar aprotic solvents, which are typically aliphatic or aromatic hydrocarbons containing at least one heteroatom such as oxygen, nitrogen, sulfur and are non-protogenic under the given conditions. Example compounds are N,N- dimethylformamide (DMF), dimethyl sulfoxide (DMSO) or 1-Methylpyrrolidin-2-one (NMP) and others, but these may sometimes lead to unwanted side reactions such as oxidation and formation of disulfides. A preferred solvent that can be used for thiolysis is pyridine as pyridine rarely leads to unwanted side reactions. All above mentioned solvents may be used alone or in combinations of at least two different solvents.

[0076] Preferably, pyridine can be used as solvent in all method steps using a solvent. Hence, drying after each method step might be omitted as the same solvent would be added anyways. For example, both thiolysis and alcoholysis can be carried out in pyridine.

[0077] The thiolysis reagent may be at least one selected from the group consisting of monothiols, dithiols, trithiols, and tetrathiols. Preferred thiolysis reagents are polythiols, i.e. , thiols with two or more thiol groups, more preferably dithiols or trithiols. Thus, at least one dithiol or at least one trithiol or a mixture of dithiols and trithiols can be preferably used as a thiolysis reagent. Using polythiols may enable easier processing of the thiolysis products into new materials as more reactive groups are introduced into the thiolysis products. The use of a monothiol may facilitate its separation, if needed, due to its high volatility as compared to polythiols.

[0078] Preferably, aliphatic thiols can be used as thiolysis reagents as aliphatic thiols exhibit a higher reactivity compared to other thiols such as aromatic thiols. Possible thiolysis reagents that are suitable for the thiolysis are thiols such as but not limited to ethylene glycol bis-mercaptoacetate, ethylene glycol bis(3-mercaptopropionate), 1 , 1 , 1 -tris(3- mercaptopropionyloxymethyl)propane, pentaerythritol tetra(3-mercaptopropionate), ethane-1 ,2-dithiol, 2,2'-[propane-1,3-diylbis(oxy)]di(ethane-1-thiol), 2,3-bis((2- mercaptoethyl)thio)-1 -propanethiol, (bis(2-(2-mercaptoethylthio)-3- mercaptopropyl)sulfide). If a polythiol is used as thiolysis reagent, the resulting lysis products are polythiols.

[0079] As described above, materials prone to thiolysis can be further subdivided, whereby the reactivities of the subgroups differ. For example, certain polythiourethanes can be depolymerized more quickly under the prevailing conditions or go into solution. As a result, the lysis products of the subgroups can be separated by time and / or temperature control. Thus, the lysis products of the individual subgroups can be better recycled separately than in the form of a depolymerization mixture of all subgroups. For example, the lysis products of the polythiourethanes MR7 and MR8 can be obtained separately. A separation ratio of 80 % ist possible, i.e. , at least 80 wt% of a certain PTU can be separated from a mixture of several PTUs.

[0080] For example, MR7 and MR8 can be separated by running thiolysis under time control. Temperature control may be additionally applied to enhance the separation effect. For example, MR7 can be depolymerized by thiolysis at a temperature of about 30 °C after a reaction time of about 30 minutes - 60 minutes. MR8 can be depolymerized by thiolysis at a temperature of about 60 °C after a reaction time of about 100 minutes - 7 hours. If thiolysis is carried out at a temperature of about 30 °C for a time period of about 60 minutes - 100 minutes, a mixed thiolysis product of MR7 and MR8 is obtained. Thus, if separation of MR7 and MR8 is required, such conditions should be avoided. A separation of the mixed thiolysis product of MR7 and MR8 is needed by a filtration procedure before a subsequent thiolysis to depolymerize MR8 is performed.

[0081] To further enhance the separation effect, the particle size of the materials to be separated can be adjusted prior to thiolysis, e.g., by shredding. The more homogeneous the particle size distribution, the better the separation effect, because the influence of the particle size on the thiolysis reaction is minimized. In a specific development of the inventive method, at least one thiol which is chemically identical to a thiol used for the synthesis of a material, e.g., a polythiourethane material, to be separated by thiolysis is used as a thiolysis reagent.

[0082] In other words, the thiol or thiol mixture used as thiolysis reagent can be selected from the group of polythiols that was also used to produce the material to be separated by thiolysis, e.g., polythiourethanes. This leads to the formation of thiols as thiolysis products that contain structural elements identical to the polythiourethane material subjected to thiolysis. Such thiols can subsequently be reacted to new, but chemically identical polythiourethanes. This enables the recovery of materials with a similar or even identical chemical composition, for example polythiourethanes. Such recovered polythiourethanes can be incorporated into any manufacturing process that uses polythiols as raw material, such as the manufacture of polythiourethane resins, thiole-ene resins, thiol-epoxy resins. This may contribute to less consumption of new materials. The suggested method may further include an alcoholysis step. Preferably, the alcoholysis step is performed after, for example directly after, the thiolysis step.

[0083] Within the alcoholysis step, a polymeric compound contained in the mixture to be treated is cleaved by adding at least one alcohol. Using alcoholysis, polyallyl carbonates, polyurea and polyurethane materials, which are not physically soluble due to their network structure, can be chemically depolymerized and separated. However, these materials are generally inert to thiolysis.

[0084] To separate polythiourethane materials from polyallyl carbonates, polyurea and polyurethane materials, alcoholysis should be carried out only after thiolysis since otherwise the polythiourethanes would be depolymerized under alcoholysis as well and thus could not be separated.

[0085] For performing alcoholysis, the mixture or remaining residue obtained from the previous treatment step, e.g., thiolysis, is mixed with an alcoholysis reagent. A solvent may be added, i.e., alcoholysis can be carried out with or without adding a solvent or solvent mixture. Moreover, a catalyst for promoting alcoholysis can be added. The mixture is stirred at a certain temperature, e.g., a temperature within the range from 20 °C to 160 °C, preferably from 130 °C to 145 °C, for a certain time, e.g., a time period within the range from 90 minutes to 8 hours, with the aim of depolymerizing polyallyl diglycol carbonate, polyurea and polyurethane materials, if contained, at least to such an extent that they are completely dissolved and can consequently be separated from the remaining substances in a downstream filtration step.

[0086] Possible catalysts for promoting alcoholysis are basic organic catalysts, such as but not limited to catalysts that are also suitable for transesterifications. Suitable basic organic catalysts may feature a pka (in acetonitrile) of the conjugate acid of 10 or higher for instance triazabicyclodecanes like 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) or 7-methyl- 1 ,5,7-triazabicyclo(4.4.0)dec-5-ene, diazabicycloundecenes like 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU),, 1 ,1 ,3,3-tetramethylguanidine, 1,5- diazabicyclo[4.3.0]non-5-ene, or 1,4-diazabicyclo[2.2.2]octanetriazabicylodecenes, 1,4- diazabicyclo[2.2.2]octane, or 2,2,6, 6-tetramethylpiperidin. Triazabicyclodecenes such as 1 ,3,4,6,7,8-hexahydro-2H-pyrimido[1,2- a]pyrimidine (TBD, (CAS: 5807-14-7) are preferred due to their suiting combination of basicity and limited nucleophilicity. Possible solvents may be organic polar aprotic solvents, which are typically aliphatic or aromatic hydrocarbons containing at least one heteroatom such as oxygen, nitrogen, sulfur and are non-protogenic under the given conditions. Example compounds are N,N- dimethylformamide (DMF), dimethyl sulfoxide (DMSO) or 1-Methylpyrrolidin-2-one (NMP) and others. A preferred solvent that can be used for alcoholysis is pyridine. The use of pyridine significantly reduces the required reaction temperature and reaction time. All above mentioned solvents may be used alone or in combinations of at least two different solvents.

[0087] Preferred alcoholysis reagents are polyols, i.e. , alcohols with two or more alcohol groups to enable processing of the alcoholysis products into new materials, i.e., at least one diol or at least one triol or a mixture of diols and triols can be used as alcoholysis reagent. Further preferred alcoholysis reagents are glycols, i.e., at least one glycol can be used as an alcoholysis reagent. In this case, alcoholysis can be named glycolysis. The advantage of glycols is their good availability. More preferably, diethylene glycol can be used as alcoholysis reagent. Further, if a polyol is used as alcoholysis reagent, the resulting lysis products are polyols.

[0088] In a specific embodiment, at least one alcohol, e.g., glycol, which is chemically identical to an alcohol used for the synthesis of a material to be separated by alcoholysis is used as an alcoholysis reagent.

[0089] In other words, the alcohol or alcohol mixture used as alcoholysis reagent can be selected from the group of polyols. This enables the recovery of materials that can be incorporated into the manufacturing process for polymer materials that use polyols as raw material such as the manufacture of polyurethane resins or polyester resins or as feedstock for other applications.

[0090] The suggested method may further include a physical dissolution step.

[0091] Within the physical dissolution step, a polymeric compound contained in the mixture, e.g., waste, to be treated is physically dissolved by adding at least one solvent. Using physical dissolution, polycarbonate materials, such as bisphenol A-based polycarbonates, can be physically dissolved using a suitable solvent due to their linear structure.

[0092] For performing physical dissolution, the mixture or remaining residue obtained from previous treatment steps, if any, may be mixed with a solvent and stirred at a certain temperature, e.g., a temperature within the range from 20 °C to 80 °C, preferably from 30 °C to 50 °C, for a certain time, e.g., a time period within the range from 30 minutes to 4 hours, with the aim of dissolving polycarbonates at least to such an extent that polycarbonates are completely dissolved and can consequently be separated from the remaining substances in a downstream filtration step.

[0093] The solvent used for physical dissolution may be selected from the group of aliphatic or aromatic hydrocarbons, chlorinated hydrocarbons, hydrocarbons containing heteroatoms such as oxygen, sulfur, or nitrogen, dimethylformamide, dimethylacetamide, and pyridine.

[0094] Preferred solvents and conditions are chlorinated solvents such as dichloromethane and chloroform, or heterocyclic, aromatic solvents such as pyridine, with a boiling point below 120 °C, which are preferably used at temperatures below 60 °C, more preferably at 40 °C. Polar solvents such as dimethylformamide or dimethylacetamide with a boiling point above 120 °C are also conceivable, but not preferred.

[0095] Apart from polycarbonates, further physically soluble materials such as impurities may be removed by physical dissolution. For example, the waste may be washed with a solvent or solvent mixture, such as but not limited to water or aqueous solutions, to remove the further physically soluble materials apart from polycarbonates in a first physical dissolution step. The solvent or solvent mixture used in the first physical dissolution step should dissolve the further physically soluble materials, but not the polycarbonates. After this first physical dissolution step, the remaining solids can be filtered off, washed and dried.

[0096] Alternatively, a solvent or solvent mixture can be selected that dissolves both the polycarbonates and the further physically soluble materials. This can be advantageous e.g., if either hardly any polycarbonates are present in the waste mixture besides the further physically soluble materials and recovery of polycarbonates is not worthwhile, or if selective precipitation of polycarbonates from the common solution of polycarbonates and further physically soluble materials is more efficient than stepwise dissolution. For example, a joint dissolution, precipitation of polycarbonates and drying of polycarbonates could represent a three-step process, while a two-step dissolution followed by precipitation of polycarbonates and drying represents a four-step process. The choice of variant may depend on the further physically soluble materials being present in the mixture, the required purity of polycarbonates and the amount available. Preferred solvents and conditions for a common dissolution of polycarbonates and further physically soluble materials are aliphatic or aromatic hydrocarbons, chlorinated hydrocarbons, or hydrocarbons containing heteroatoms such as oxygen and nitrogen, which can be used at room temperature.

[0097] Subsequently, polycarbonates are then dissolved from the remaining mixture in a second physical dissolution step, unless polycarbonates have been dissolved as described above or polycarbonates are not present in the mixture.

[0098] After alcoholysis, materials that can neither be physically dissolved nor depolymerized under given thiolysis and alcoholysis conditions remain and can be either disposed of or otherwise utilized.

[0099] In a further specific development of the inventive method, the method may include obtaining information on a composition of the mixture and deriving instructions for carrying out the separation of the different polymeric spectacle lens materials based on the obtained information.

[0100] Preferably, these two steps can be carried out before the actual treatment of the mixture.

[0101] The obtained information can be used to assess the economic efficiency of the process and to decide whether all process steps should be carried out or only a selection. In addition, the information about the composition enables the calculation of the necessary quantities of solvents, catalyst and / or other reagents. Thus, detailed instructions for carrying out the separation of the different materials can be derived leading to a more efficient separation process, e.g., in terms of chemicals and energy consumption. Moreover, separation products of better quality, e.g., purity, can be obtained.

[0102] In a further specific development of the inventive method, the method may include a shredding step.

[0103] Preferably, shredding may be carried out as the first method step. Alternatively or additionally, shredding may be carried out after a drying step. Shredding may enhance the efficiency of the subsequent method steps. For example, shredding can reduce drying times or reaction times by increasing the surface area and thus reduce the time required and energy costs. A particle size of < 2 mm may be preferred. The use of cryomilling for shredding can also be advantageous, as it makes it easier to achieve small particles as the material is becoming more brittle. Furthermore, it may be advisable to carry out the shredding step in a temperature-controlled manner, preferably at temperatures below 100 °C or more preferably at temperatures below 60 °C, to prevent undesirable changes to the material.

[0104] In a further specific development of the inventive method, the method may include a drying step.

[0105] Preferably, drying can be carried out before carrying out any of the physical dissolution step, the thiolysis step and / or the alcoholysis step. The process may begin, possibly after the shredding step, with a drying process or with a washing step after which the drying is carried out to reduce any water contained, for example to a maximum water content of 5 wt%, preferably 2 wt%, more preferably 1 wt%. Drying may facilitate the further separation steps. For example, unwanted side reactions due to water may be avoided and / or corrosion of equipment can be reduced.

[0106] During the drying step, the material may be subjected to heating. More specifically, the material may be subjected to temperatures up to 100 °C, more preferably to up to 80 °C and even more preferably to up to 60 °C in order to avoid degradation of the material. Further, during drying, the material may be subjected to a vacuum, i.e. , a pressure of below 1 atm. Further, during drying, the material may be subjected to agitation, i.e., the material may be moved by mechanisms such as stirring or shaking in order to ease the release of compounds that are volatile under the drying conditions.

[0107] In a further specific development of the inventive method, the method may include producing a reaction product, e.g., a polymer, selected from the group of polythiourethanes, thiol-epoxy resins and reaction products of a thiol-ene reaction using a thiolysis product obtained from the thiolysis step.

[0108] In addition to the solvent or solvent mixture, the catalyst or catalyst mixture and the thiolysis reagent used in the thiolysis step, the solution obtained in the thiolysis step also contains thiourethane compounds. These thiourethane compounds are polythiol compounds. The resulting solution can be purified, and the solvent removed to obtain a polymerizable polythiol mixture. This polythiol mixture can be converted back into valuable products in typical reactions. These are, for example, polythiourethanes, thiolepoxy resins, reaction products of a thiol-ene reaction.

[0109] Thus, the thiolysis products can be reused and contribute to a functioning circular economy.

[0110] In a further specific development of the inventive method, the method may include producing a reaction product, e.g., a polymer, selected from the group of polyurethanes, epoxy resins and polyesters from an alcoholysis product obtained from the alcoholysis step.

[0111] In addition to the solvent or solvent mixture, the catalyst or catalyst mixture and the alcoholysis reagent used in the alcoholysis step, the solution obtained in the alcoholysis step may also contain polycarbonate compounds, polyurethane compounds, polyurea compounds or combinations of polyurethane and polyurea compounds. The polycarbonate compounds, polyurethane compounds, polyurea compounds or combinations of polyurethane and polyurea compounds are polyol compounds. The resulting solution can be purified, and the solvent removed to obtain a polymerizable polyol mixture. This can be converted back into valuable products in typical reactions. These are, for example, polyurethanes, epoxy resins and polyesters.

[0112] Thus, the alcoholysis products can be reused and contribute to a functioning circular economy.

[0113] In a further specific development of the inventive method, the method may include producing a solid polycarbonate from a solution obtained from the physical dissolution step.

[0114] In addition to the solvent or solvent mixture used in the physical dissolution step, the solution obtained in the physical dissolution step may also contain dissolved polycarbonate. This dissolved polycarbonate can subsequently be converted back into a pure polycarbonate solid in a suitable non-solvent or by removing the solvent, the molecular weight and dispersity of which largely corresponds to that of the starting polymer before dissolution. The changes presumably result mainly from small losses of particularly soluble or insoluble components depending on the molecular weight distribution. Thus, the product of the physical dissolution step can be reused and contribute to a functioning circular economy.

[0115] In a further aspect, the invention provides a method for separating at least one polythiourethane from a mixture comprising at least two different polythiourethanes by thiolysis. The polythiourethane material may be a spectacle lens material.

[0116] By using the suggested method, a number of chemically distinct polythiourethanes can be separated from each other.

[0117] A thiolysis reagent which is at least one selected from the group consisting of monothiols, dithiols, trithiols, and tetrathiols can be used in thiolysis.

[0118] The thiolysis reagent may comprise at least one thiol, wherein the at least one thiol is identical to a thiol used for the synthesis of the at least one polythiourethane to be separated by thiolysis.

[0119] Further, a strong basic catalyst and / or a polar aprotic solvent can be used in thiolysis.

[0120] In a specific development, thiolysis is carried out under time control and / or temperature control.

[0121] For example, MR7 and MR8 can be separated by running thiolysis under time control. Temperature control may be additionally applied to enhance the separation effect.

[0122] To further enhance the separation effect, the particle size of the materials to be separated can be adjusted prior to thiolysis, e.g, by shredding. The more homogeneous the particle size distribution, the better the separation effect, because the influence of the particle size on the thiolysis reaction is minimized.

[0123] In a specific development, the mixture comprising at least two different polythiourethanes may further comprise at least one polymeric material selected from the group consisting of polyallyl carbonate, polyurea, polyurethane, polyurethane / polyurea, polycarbonate, polyepisulfide, and polythiourethane. At least one of the polymeric materials may be a spectacle lens material.

[0124] In a further development, the mixture consists of spectacle lens materials. For further aspects concerning the thiolysis to separate the at least one polythiourethane from the mixture comprising at least two different polythiourethanes, it is referred to the above description of the thiolysis step. Some or all of the other method steps described above may be incorporated into the method for separating the at least one polythiourethane as appropriate.

[0125] BRIEF DESCRIPTION OF THE DRAWINGS

[0126] Further features, properties and advantages of the present invention will become clear from the following description of embodiments in conjunction with the accompanying drawings.

[0127] Figure 1 shows a table (table 1) listing typical materials used in the optical industry, the associated material classes, and optical parameters.

[0128] Figure 2 shows a flowchart illustrating a method for separating different spectacle lens materials in a mixture comprising at least two different polymeric spectacle lens materials.

[0129] Figure 3 shows a table (table 2) listing parameters of several examples of the proposed method.

[0130] Figure 4 shows a reaction scheme of a thiolysis step using a dithiol as thiolysis reagent including a potential usage of the thiolysis product in the reaction with a diisocyanate.

[0131] Figure 5 shows a reaction scheme of a thiolysis step using a trithiol as thiolysis reagent including a potential usage of the thiolysis product in the reaction with a diisocyanate.

[0132] Figure 6 shows a flowchart illustrating a method for separating at least one polythiourethane from a mixture comprising at least two different polythiourethanes.

[0133] Figure 7 shows an IR spectrum of the mixture of polymeric lens materials in example A.

[0134] Figure 8 shows an IR spectrum of the PTU MR7 to be removed from the starting mixture in example A.

[0135] Figure 9 shows an IR spectrum of the PTU MR8 to be removed from the starting mixture in example A.

[0136] Figure 10 shows an IR spectrum of the filtered of solids after thiolysis.

[0137] Figure 11 shows an IR spectrum of pure CR39 for reference.

[0138] Figure 12 shows an IR spectrum of pure MR174 for reference.

[0139] Figure 13 shows an IR spectrum of the filtrate containing the dissolved PTU material.

[0140] Figure 14 shows an IR spectrum of thiolysis reagent as reference.

[0141] Figure 15 shows an IR spectrum of the filtered off solids after glycolysis.

[0142] Figure 16 shows an IR spectrum of the filtrate containing the dissolved CR39.

[0143] Figure 17 shows an IR spectrum of glycolysis reagent as reference.

[0144] Figure 18 shows a table (table 3) summarizing the results of separation of MR7 and MR8.

[0145] With reference to figure 2, an exemplary method 100 for separating different polymeric spectacle lens materials in a mixture is explained in more detail. The mixture consists of waste of polymeric spectacle lenses and / or waste from the manufacture of polymeric spectacle lenses, however, other mixtures comprising at least two different polymeric spectacle lens materials can be processed in the same way. The aim is to enable the value-adding use or recycling of mixed plastic waste, including grinding and milling waste, from the manufacture of polymeric spectacle lenses as well as waste of polymeric spectacle lenses. This is achieved by exploiting the different behavior of the materials contained in the waste towards different chemical environments. Concepts known from the literature, such as thiolysis and alcoholysis, are optimized and combined for the desired problem solution. As a result, the substance or material classes present in the mixture can be selectively extracted from the mixture one after the other.

[0146] First, the above-mentioned substance classes are further classified. The first group is thermoplastic polycarbonate as defined above, preferably bisphenol A-based polycarbonate, referred to below as PC. PCs can be physically dissolved using a suitable solvent due to its linear structure.

[0147] The second group consists of polythiourethane materials, referred to below as PTU. PTUs are not physically soluble due to their network structure. In addition, they can be chemically depolymerized, both by using a thiolysis process and by using an alcoholysis process. The second group can be further divided into subgroups, each with a different affinity to depolymerize under given thiolysis conditions.

[0148] The third group consists of polyallyl diglycol carbonate, preferably polyallyl diglycol carbonate, referred to below as PADC, polyureas, polyurethanes and polyurethanes. These materials are also network polymers and can be depolymerized by alcoholysis. However, they are inert to thiolysis, at least under certain process conditions.

[0149] The fourth group consists of materials which, in addition to the materials already mentioned, can also be contained in the waste mixture and can neither be physically dissolved nor depolymerized under given thiolysis and glycolysis conditions, such as polyepisulfides.

[0150] The fifth group consists of materials which, in addition to the materials already mentioned, may also be contained in the waste mixture and which can also be physically dissolved, whether under the same conditions as the PC or under other conditions. This classification and composition of the waste is used in the method described below to enable the waste to be separated and valuable products to be obtained.

[0151] In a first method step SO, information on the composition of the waste is obtained in order to derive instructions for carrying out the separation of the different materials in method step S1. For example, it can be decided whether all method steps should be carried out or only a selection. Moreover, the economic efficiency of the process may be assessed. In addition, the information about the composition enables the calculation of the necessary quantities of solvent, catalyst and / or other reagents. The qualitative and / or quantitative information on the composition of the waste may be obtained by performing chemical or physical analysis such as infrared spectroscopy, solubility tests, determination of density, elemental analysis, determination of melting point, if any. The waste treatment begins with a shredding step S2 to achieve a higher efficiency for the subsequent method steps. Shredding reduces reaction times by increasing the surface area and thus reduces the time required and energy costs. A particle size of < 2 mm is preferred. In a specific embodiment, shredding is performed using cryomilling making it easier to achieve small particles. The temperature during shredding is kept below 60 °C to prevent undesirable changes to the materials. The shredding step S2 can be left out if the material already exhibits the preferred particle size.

[0152] After drying, the waste is then dried in a drying step S3 to reduce any water contained to a maximum water, e.g. a water content of about 5 wt%. However, the drying step S3 can be left out if the material already has a water content below the maximum water content. The shredding step S2 and drying step S3 can also be performed in reverse order.

[0153] Method step S4 is a physical dissolution step which can either be performed as one single step S4 or separated into a first physical dissolution step S4a and a second physical dissolution step S4b.

[0154] If two physical dissolution steps are used the shredded waste is washed with a solvent or solvent mixture to remove impurities of the fifth material group from the mixture during the physical dissolution step S4a. The solvent or solvent mixture should dissolve out materials of group 5, but not materials of the first group, i.e., polycarbonates. After the first physical dissolution step S4a, the remaining solids are filtered off, washed and dried.

[0155] If one single physical dissolution step S4 is used a solvent or solvent mixture is selected that dissolves materials of the first and fifth. This can be advantageous if either hardly any PCs are present in the waste and recovery of PCs is not worthwhile, or if selective precipitation of PCs from the solution of PCs and materials of the fifth group is more efficient than stepwise dissolution. For example, a joint physical dissolution in a single physical dissolution step S4, precipitation of PCs and drying of PCs could represent a three-step process, while a two-step dissolution followed by precipitation of PCs and drying represents a four-step process. The choice of variant here depends on the materials of the fifth group contained in the waste, the required purity of PCs and the amount available. Preferred solvents and conditions are aliphatic hydrocarbons, which can be used at room temperature.

[0156] In the second physical dissolution step S4b, PCs are then dissolved from the remaining waste, unless PCs have been dissolved as described above in the common physical dissolution step S4 or PCs are not present in the mixture. Preferred solvents and conditions are chlorinated solvents such as dichloromethane and chloroform, or heterocyclic, aromatic solvents such as pyridine, with a boiling point below 120 °C, which are preferably used at temperatures below 60 °C, more preferably at 40 °C. Polar solvents such as dimethylformamide or dimethylacetamide with a boiling point above 120 °C are also conceivable. After dissolving the materials of the first group, i.e. , PCs, the remaining solid is filtered off, washed and dried. The IR spectrum of the separated PC resembles the spectrum of virgin PC after drying confirming the nature of the dissolved material.

[0157] Method step S5 is the thiolysis step. In this step S5, materials of the second group are depolymerized. The solid obtained after the physical dissolution step S4 is mixed with solvent, catalyst and thiolysis reagent and stirred at a certain temperature for a certain time with the aim of depolymerizing the materials of the second group at least to such an extent that these materials are completely dissolved and can consequently be separated from materials of the third group in a downstream filtration step. Preferred conditions are listed in table 2 of fig. 3, Example I. Examples II and III represent alternative thiolysis conditions. After thiolysis, the remaining solid is filtered off, washed and dried.

[0158] As described above, the materials of the second group can be further subdivided, whereby the reactivities of the subgroups differ. For example, certain PTUs can be depolymerized more quickly under the prevailing conditions or go into solution. As a result, the lysis products of the subgroups can be separated by time control. Advantageously, the lysis products of the individual subgroups can be better recycled separately than in the form of a depolymerization mixture of all subgroups of the second group. For example, the lysis products of MR7 and MR8 can be obtained separately.

[0159] Method step S6 is the alcoholysis step, preferably glycolysis. In this step, the materials of the third group are depolymerized. The solid from method step S5 is mixed with solvent, catalyst and glycolysis reagent and stirred at a certain temperature for a certain time with the aim of depolymerizing the materials of the third group at least to such an extent that they are completely dissolved and can therefore be separated from the materials of the fourth group in a downstream filtration step. Preferred conditions are shown in table 2 of fig. 3, Example V. After dissolving the materials of the third group, the remaining solid is filtered off, washed and dried.

[0160] Method step S7 comprises the handling of the materials of the fourth group, if any, which cannot be chemically recycled during the proposed method 100 and should either be disposed of or otherwise utilized.

[0161] The method 100 described above can also be carried out only partially, depending on the application objective and initial composition of the waste. Although the general sequence should be followed, the thiolysis step S5 can be omitted, for example, if no PTU is contained in the waste. If the aim of the method 100 is to enrich the materials of the third group for another subsequent process, the method can be aborted after the thiolysis step S5. Further conceivable variations depending on the aim of the method 100 and the composition are possible.

[0162] The liquid products obtained in the individual steps S4 to S6 are defined in more detail below. The solution / suspension obtained in the method step S4 consists of the solvent or solvent mixture used and any auxiliary substances used during processing, such as abrasives and lubricants or other low-molecular compounds. In the case of the combined dissolution of materials of the first and fifth group, PC is also contained in the solution.

[0163] If two physical dissolution steps S4a, S4b are used, the solution obtained after the second physical dissolution step S4b contains the solvent or solvent mixture used and the dissolved PC. PC can subsequently be converted back into a pure PC solid in a suitable non-solvent or by removing the solvent, the molecular weight and dispersity of which largely corresponds to that of the starting PC polymer before dissolution. The changes presumably result mainly from small losses of particularly soluble or insoluble components depending on the molecular weight distribution. The above also applies if the PC is precipitated from the solution obtained in a common physical dissolution step S4.

[0164] In addition to the solvent or solvent mixture used, the catalyst or catalyst mixture used and the thiolysis reagent, the solution obtained in the thiolysis step S5 also contains thiourethane compounds. These thiourethane compounds are polythiol compounds. The resulting solution can be purified, and the solvent removed to obtain a polymerizable polythiol mixture. The viscosity of the resulting solution was 3.7 Pa*s. This polythiol mixture can be converted back into valuable products in typical reactions. These products are, for example, PTUs, thiol-epoxy resins, reaction products of a thiol-ene reaction. The solution obtained in the alcoholysis step S6 contains, in addition to the solvent or solvent mixture used, the catalyst or catalyst mixture used and the glycolysis reagent, polycarbonate compounds, polyurethane compounds, polyurea compounds or combinations of polyurethane and polyurea compounds. The polycarbonate compounds, polyurethane compounds, polyurea compounds or combinations of polyurethane and polyurea compounds are polyol compounds. The viscosity of the resulting solution was 0.06 Pa*s, the OH content was 5.4 mmol (OH) / g (sample). The resulting solution can be purified, and the solvent removed to obtain a polymerizable polyol mixture. This polyol mixture can be converted back into valuable products in typical reactions. These are, for example, PLIRs, epoxy resins and polyesters.

[0165] It is to be noted that some of the method steps described with respect to figure 2 can be left out or additional steps may be added as appropriate. For example, the shredding step S2 can be left out if the particle size is already small enough. The physical dissolution step S4 can be left out if no materials are present which can be dissolved physically. The drying step S3 can be left out, for example, if the water content is already low enough.

[0166] Table 2 shown in figure 3 lists examples I to V of single-origin materials, examples A and B of material mixtures and one counter-example. For each example, its composition with respect to the materials of the 1stto 5thgroup and the conditions for their separation, i.e., process chemicals and processing parameters such as catalyst, depolymerizing reagent, solvent, and temperature are given. Moreover, the coloration of the depolymerized phase is mentioned. The dried spectacle lens material was added as milling chips to a glass reactor and mixed with the process chemicals given in figure 3, columns “I” to “V”. The formed suspension was heated under continuous stirring. The mixture was stirred until the material was dissolved. Subsequently, the mixture was filtered to obtain a filtrate containing the dissolved material. The filtrate was measured by IR spectroscopy confirming the expected signals of lysis reagent and dissolved material.

[0167] Examples I, II, III, and IV use different mass fractions of materials of the 2ndgroup, i. e. MR7 or MR8 as polythiourethanes, that are treated by thiolysis using a thiolysis reagent, i.e. either 4-(mercaptomethyl)-3,6-dithia-1,8-octanedithiol in different mass fractions (examples I to III) or Ethylenbis(3-mercaptopropionat) (example IV). Pyridine was used as solvent and Triazabicyclodecene was added as catalyst in different mass fractions as shown in figure 3. Thiolysis was performed by either 65 °C or 85 °C. Example I represents preferred thiolysis conditions as the PTU material was depolymerized and dissolved within 7 h and a clear, yellowish depolymerized phase could be obtained. Examples II and

[0168] III represent alternative thiolysis conditions: the PTU materials were depolymerized and dissolved more quickly as compared to example I. However, the material balance is less favorable, i.e. , a higher proportion of thiolysis reagent and / or solvent is required. Example

[0169] IV represents alternative thiolysis conditions using a different thiolysis reagent, however, the reaction time was much longer as compared to examples I to III. Thus, the preferred thiolysis reagent is 4-(mercaptomethyl)-3,6-dithia-1 ,8-octanedithiol.

[0170] Example V contains material of the 3rdgroup, i.e., CR39, and is thus treated by alcoholysis using diethylene glycol as alcoholysis reagent. Pyridine was used as solvent. Within 8 h, depolymerization took place leading to a dark brown colored depolymerized phase.

[0171] The counter example shows that materials of the 3rdgroup are not prone to thiolysis, i.e., no depolymerization took place. The dried spectacle lens material was added as milling chips to a glass reactor and mixed with the process chemicals given in figure 3, column “counter-example”. The formed suspension was heated under continuous stirring. The mixture was stirred for 8 h during which the material was not dissolved. Thus, a mixture of materials of the 2ndand 3rdgroup can be separated be thiolysis which leads to depolymerization of the materials of the 2ndgroup, but not of the materials of the 3rdgroup.

[0172] Examples A and B represent material mixtures with mass fractions as shown in figure 3 that belong to a sequential experiment. In a first step, thiolysis was performed on mixture A consisting of materials of the 2nd, 3rd, and 4thgroup, namely MR7 and MR8 of the 2ndgroup, CR39 of the 3rdgroup and MR174 of the 4thgroup. Figure 7 shows an IR spectrum of the polymeric lens material mixture A.

[0173] The dried mixture of spectacle lens materials was added as milling chips to a glass reactor and mixed with the process chemicals given in figure 3, column “material mixture A”. The formed suspension was heated under continuous stirring to 65 °C. The mixture was stirred at 65 °C for 7h. Subsequently, the mixture was filtered to obtain a filtrate containing the dissolved materials of the 2ndgroup and a solid containing the materials of the 3rdand 4thgroup. A clear, yellow colored depolymerized phase as filtrate and a solid residue of about 15 wt% was obtained under the reaction conditions mentioned above and shown in figure 3.

[0174] The filtrate was measured by IR spectroscopy confirming the expected signals of thiolysis reagent and dissolved materials of the 2ndgroup. Figure 8 shows a reference IR spectrum of MR7, which is to be removed as material of the 2ndgroup. Most relevant signals to look at are - 3280 cm-1, - 1640 cm-1, - 1490 cm-1, and - 1190 cm-1. Figure 9 shows a reference IR spectrum of MR8, which is to be removed as material of the 2ndgroup. Most relevant signals to look at are - 3295 cm-1, - 2940 cm-1, - 1735 cm-1, - 1650 cm-1, -1510 cm-1, and - 1190 cm-1. Figure 13 shows the IR spectrum of the filtrate containing the dissolved PTU materials, i.e., MR7 and MR8. As expected, signals of the dissolved MR7 and MR8 as well as thiolysis reagent are visible. Most relevant signals to look at are - 3300 cm’1, - 2915 cm’1, - 2540 erm1, - 1735 erm1, - 1660 erm1, - 1500 erm1, - 1195 erm1. For reference, figure 14 shows the IR spectrum of the thiolysis reagent.

[0175] The solid was washed with pyridine, dried and measured by IR spectroscopy confirming the expected signals of the materials of the 3rdand 4thgroup. Figure 10 shows the corresponding IR spectrum of the filtered of solids after thiolysis, which mainly resembles the IR spectrum of CR 39 (please see figure 11 for reference). Prominent signals of MR7 and MR8 are not visible anymore indicating the successful thiolysis and separation.

[0176] Figure 12 shows a reference IR spectrum of MR174. MR174 is also contained in the solid and thus reflected by the IR spectrum shown in figure 10. However, due to its low intensity signals and low content in the mixture it is not distinguishable. The determined mass of the dried solid of 15 % of the mass of the initially added spectacle lens material confirmed the inertness of the materials of the 3rdand 4thgroup under thiolysis conditions and their remaining for further recycling.

[0177] The solid residue comprising the materials of the 3rdand 4thgroup represents mixture B, namely CR39 of the 3rdgroup and MR174 of the 4thgroup. Mixture B was subsequently treated under alcoholysis conditions. Mixture B was subjected to a glass reactor together with the respective process chemicals given in figure 3, column “material mixture B” for the alcoholysis or glycolysis step, respectively. The formed suspension was heated under continuous stirring to 145 °C and stirred at 145 °C for 1.5 h. Subsequently, the mixture was filtered to obtain a filtrate containing the dissolved materials of the 3rdgroup, i.e., CR39 and a solid containing the material of the 4thgroup, i.e., MR174. By alcoholysis using diethylene glycol as alcoholysis reagent, the material of the 3rdgroup was depolymerized and only little residue (materials of the 4thgroup) of less than 2 wt% was obtained. The filtrate was measured by IR spectroscopy confirming the expected signals of glycolysis reagent and dissolved materials of the 3rdgroup. Figure 16 shows the IR spectrum of the filtrate after glycolysis containing the dissolved CR39. As expected, signals of the dissolved material from the 3rd group, i.e., CR39, as well as glycolysis reagent are visible. Most relevant signals to look at are ~ 3340 cm-1, ~ 2860 cm-1, ~ 1745 cm-1, ~ 1273 cm-1, ~ 1050 cm-1. Figure 17 shows the IR spectrum of the glycolysis reagent as reference.

[0178] The solid was washed with pyridine, dried and measured by IR spectroscopy confirming the expected signals of the material of the 4thgroup. Figure 15 shows the corresponding IR spectrum of the filtered off solids, containing mainly MR174 besides traces of CR39 which are well visible due to the low intensity of the MR174 material. Prominent signals of MR174 are visible at ~ 2895 cm-1, ~ 1400 cm-1, signals of trace CR39 are visible at ~ 1735 cm-1, ~ 1240 cm-1. The area 2245 cm-1to 2418 cm-1showed a prominent signal of CO2, which was attributed to the surrounding atmosphere. This signal was excluded from the spectrum to increase visibility while maintaining the validity of the data. The determined mass of the dried solid of < 2 % of the mass of the initially added spectacle lens material confirmed the inertness of the materials of the 4thgroup under glycolysis conditions and their remaining for further potential recycling.

[0179] The depolymerized phase obtained after thiolysis can be used to produce a reaction product which is at least one selected from the group consisting of polythiourethanes, thiol-epoxy resins and reaction products of a thiol-ene reaction. The depolymerized phase obtained after alcoholysis can be used to produce a reaction product which is at least one selected from the group consisting of polyurethanes, epoxy resins and polyesters.

[0180] A further experiment has been carried out to confirm the behaviour of the polyepisulfide MR174 under thiolysis conditions. The IR spectrum of the remaining solid after attempted thiolysis resembles virgin MR174 mixed with the thiolysis reagent Thiocure, whereas the IR spectrum of the filtrate resembles the thiolysis reagent without visible signals of MR174, confirming that no lysis of MR174 took place.

[0181] Figure 4 shows a reaction scheme of a thiolysis step using a dithiol as thiolysis reagent. The first reaction shown represents the synthesis of a polythiourethane (III) from trithiols (I) and diisocyanates (II). Such polythiourethanes (III) may be present in waste of polymeric spectacle lenses and / or waste from the manufacture of polymeric spectacle lenses as materials of the second group which are prone to thiolysis. Thus, polythiourethanes (III) can be depolymerized by using a thiolysis reagent and separated from the remaining waste.

[0182] As shown in figure 4, a dithiol (IV) can be used as thiolysis reagent. Upon adding the dithiol (IV) to the polythiourethane (III) depolymerization takes place.

[0183] The depolymerization product (V), which may be an oligomer, can be separated from insoluble waste components, such as polyepisulfides, as it is soluble in the chosen solvent, e.g., pyridine. Thereafter, the depolymerization product (V) can react, with an isocyanate (VI) different to the isocyanate (II) to build a new polythiourethane network polymer (VII), i.e., a polythiourethane other than the previous polythiourethane (III), as shown in figure 4. Alternatively or additionally, the depolymerization product (V) can react with the same isocyanate (II) to also obtain a polythiourethane other than the previous polythiourethane (III). Moreover, other reactions of the depolymerization product (V), e.g., with epoxys, olefines, alkynes etc. are possible resulting in other polymer materials.

[0184] Figure 5 shows a reaction scheme of a thiolysis step using a trithiol as thiolysis reagent. The first reaction shown represents the synthesis of a polythiourethane (III) from trithiols (I) and isocyanates (II) in agreement with the reaction scheme of figure 4. Such polythiourethanes (III) may be present in waste of polymeric spectacle lenses and / or waste from the manufacture of polymeric spectacle lenses as materials of the second group which are prone to thiolysis. Thus, polythiourethanes (III) can be depolymerized by using a thiolysis reagent and separated from the remaining waste.

[0185] As shown in figure 5, a trithiol (I) can be used as thiolysis reagent instead of the dithiol (IV) used in the reaction scheme of figure 4. As shown in figure 5, trithiols that are identical to the trithiol (I) used for the synthesis of a material to be separated by thiolysis can be used to enable the recovery of polythiourethanes with identical structural elements as the starting PTU (III). Upon adding the trithiol (I) to the polythiourethane (III), depolymerization takes place. The depolymerization product (XI), which may be an oligomer, can be separated from insoluble waste components, such as polyepisulfides, as it is soluble in the chosen solvent, e.g., pyridine.

[0186] If the trithiols (I) used as thiolysis reagent is chemically identical to the thiol (I) used for the synthesis of the polythiourethane (III), it is possible to almost exactly recover the polythiourethane (III) by reaction of the depolymerization product (XI) with further isocyanate (II), i.e. , an identical polymer can be obtained. Alternatively, the depolymerization product (XI) can be reacted with a different isocyanate and / or a different thiol may be used as thiolysis reagent to obtain a different polythiourethane.

[0187] It is to be understood that PTUs consisting not only of two components, but also, for example, are made using two different thiols and / or different isocyanates or, in other words, PTUs made from a mixture of polythiols and a mixture of polyisocyanates can be equally processed.

[0188] With reference to figure 6, an exemplary method 200 for separating at least one polythiourethane from a mixture comprising at least two different polythiourethanes is explained in more detail. The mixture consists of waste of polymeric spectacle lenses and / or waste from the manufacture of polymeric spectacle lenses, however, other mixtures comprising at least two different polythiourethanes can be processed in the same way. The aim is to enable the value-adding use or recycling of mixed plastic waste, including grinding and milling waste, from the manufacture of polymeric spectacle lenses as well as waste of polymeric spectacle lenses. This is achieved by exploiting the different behavior of the materials contained in the waste.

[0189] In the exemplary method 200, a mixture comprising the polythiourethanes MR7, MR8, and the polyallylcarbonate CR39 is treated such that these two polythiourethanes and the CR39 are separated from each other.

[0190] The method 200 starts with a pretreatment step 20. Within the pretreatment step 20, one or more pretreatments including washing, shredding, drying etc. may be carried out as appropriate. Moreover, the pretreatment step 20 may comprise obtaining information on the compostion of the mixture. For more details, it is referred to the above description of method steps SO to S4a.

[0191] After the pretreatment step S20, a 1stthiolysis step S21 is carried out for separating MR7 from MR8 and CR39. The reaction conditions of the 1stthiolysis step 21 may be as follows: thiolysis reagent: 4-(mercaptomethyl)-3,6-dithia-1 ,8-octanedithiol, catalyst: 1 ,3,4,6,7,8-hexahydro-2H-pyrimido[1 ,2- a]pyrimidine, solvent: pyridine, reaction time: 20 - 60 min, preferably 30 - 45 min, temperature: 20 °C - 40 °C, preferably 30 °C.

[0192] During the 1stthiolysis step S21 , MR7 is at least partly depolymerized and becomes a liquid whereas MR8 and CR39 remain solid and can be separated, e.g., by filtration.

[0193] After 1stthiolysis step S21 , a 2ndthiolysis step S22 is carried out for separating MR8 from CR39. The reaction conditions of the 2stthiolysis step 22 may be as follows: thiolysis reagent: 4-(mercaptomethyl)-3,6-dithia-1 ,8-octanedithiol, catalyst: 1 ,3,4,6,7,8-hexahydro- 2H-pyrimido[1 ,2- a]pyrimidine, solvent: pyridine, reaction time: 100 min - 420 min, preferably 200 min - 300 min, temperature: 40 °C - 80 °C, preferably 50 - 70 °C.

[0194] During the 2ndthiolysis step S22, MR8 is at least partly depolymerized and becomes a liquid whereas CR39 remains solid and can be separated, e.g., by filtration. Optionally, an alcoholysis step can be carried out to depolymerize CR39.

[0195] Optionally, the reaction conditions of the 2ndthiolysis step S22 and possibly any further thiolysis steps may be the same as for the 1stthiolysis step with the exception of reaction time / and or temperature. In other words, thiolysis may be carried out under time control and / or temperature control.

[0196] Subsequently, reaction products which are at least one selected from the group consisting of polythiourethanes, thiol-epoxy resins and reaction products of a thiol-ene reaction can be produced from the (partly) depolymerized polythiourethanes.

[0197] For further details on thiolysis, it is referred to the above description of method step S5.

[0198] For further details on alcoholysis, it is referred to the above description of method step S6.

[0199] Preferably, an intermediate step may be added after the 1stthiolysis step and before the 2ndthiolysis step for separating a mixture comprising thiolysis products of MR7 and MR8. The reaction conditions of the 2stthiolysis step 22 may be as follows: thiolysis reagent: 4- (mercaptomethyl)-3,6-dithia-1 ,8-octanedithiol, catalyst: 1 ,3,4,6,7,8-hexahydro-2H- pyrimido[1 ,2- a]pyrimidine, solvent: pyridine, reaction time: 60 min - 100 min, temperature: 30 °C. During the intermediate step, some MR7 and some MR8 is at least partly depolymerized and becomes a liquid mixed product whereas the major part of MR8 remains solid as well as CR39 and can be separated, e.g., by filtration. The solid residue can further be treated by thiolysis according to the 2ndthiolysis step S22 to separate MR8.

[0200] Please note that all method steps described herein were performed under atmospheric pressure, i.e., a pressure of 101 ,325 Pa, unless otherwise stated. A pressure other than atmospheric pressure may be used by adjusting the specified temperatures.

[0201] With reference to figure 18, an examplary method 200 for the separation of MR7 and MR8 is described in detail. The starting mixture consisted of 9.5 wt% MR7, 9.5 wt% MR8, 34.3 wt% 4-(mercaptomethyl)-3,6-dithia-1 ,8-octanedithiol , 0.4 wt% 1 ,3,4,6,7,8-hexahydro-2H- pyrimido[1 ,2- a]pyrimidine, and 46.3 wt% pyridine corresponding to the following initial weights: 35.26 g MR7, 35.26 g MR8, 126.92 g 4-(mercaptomethyl)-3,6-dithia-1 ,8- octanedithiol, 1.54 g 1 ,3,4,6,7,8-hexahydro-2H-pyrimido[1 ,2- a]pyrimidine, and 171.54 g pyridine.

[0202] For carrying the 1stseparation step, the reaction mixture was stirred for 90 minutes at 30 °C. The suggested range of reaction time is 60 - 120 minutes, more preferably 80 - 100 minutes, even more preferably 90 minutes. The suggested range of reaction temperature is 20 °C - 40 °C, more preferably 30 °C. Samples were taken every 15-30 minutes. After the 1stseparation step, the mixture was filtered using a pressurized filter unit and the solids were washed with pyridine. The liquid fractions were concentrated in vacuo and analyzed using ATR-FT-IR spectroscopy and Raman spectroscopy. The solids were dried in a vacuum drying oven and also analyzed. The remaining solid content after the 1stseparation step was 34.15 g.

[0203] For carrying out the 2ndseparation step, the remaining solid of the 1stseparation step was mixed with 126.92 g 4-(mercaptomethyl)-3,6-dithia-1 ,8-octanedithiol, 1.54 g 1 , 3, 4, 6,7,8- hexahydro-2H-pyrimido[1 ,2- a]pyrimidine, and 171.54 g pyridine. The reaction mixture was stirred for 60 minutes at 30 °C. The suggested range of reaction time is 30 - 90 minutes, more preferably 50 - 70 minutes, even more preferably 60 minutes. The suggested range of reaction temperature is 20 °C - 40 °C, more preferably 30 °C. Samples were taken every 15 minutes. After the 2ndseparation step, the mixture was filtered using a pressurized filter unit and the solids were washed with pyridine. The liquid fractions were concentrated in vacuo and analyzed using ATR-FT-IR spectroscopy and Raman spectroscopy. The solids were dried in a vacuum drying oven and also analyzed. The remaining solid content after the 2ndseparation step was 25.9 g.

[0204] For carrying out the 3rdseparation step, the remaining solid of the 2ndseparation step was mixed with 126.92 g 4-(mercaptomethyl)-3,6-dithia-1 ,8-octanedithiol, 1.54 g 1 , 3, 4, 6,7,8- hexahydro-2H-pyrimido[1 ,2- a]pyrimidine, and 171.54 g pyridine. The reaction mixture was stirred for 7 hours at 30 °C. The suggested range of reaction time is 5 - 10 hours, more preferably 6 - 8 hours, even more preferably 7 hours. The suggested range of reaction temperature is 20 °C - 40 °C, more preferably 30 °C. Samples were taken every 15 minutes. After the 3rdseparation step, the mixture was filtered using a pressurized filter unit and the solids were washed with pyridine. The liquid fractions were concentrated in vacuo and analyzed using ATR-FT-IR spectroscopy and Raman spectroscopy. The solids were dried in a vacuum drying oven and also analyzed. The remaining solid content after the 3rdseparation step was 9 g.

[0205] For carrying out the 4thseparation step, the remaining solid of the 3rdseparation step was mixed with 16.2 g 4-(mercaptomethyl)-3,6-dithia-1 ,8-octanedithiol, 0.2 g 1 , 3, 4, 6,7,8- hexahydro-2H-pyrimido[1 ,2- a]pyrimidine, and 21.9 g pyridine. The reaction mixture was stirred for 7 hours at 60 °C. The suggested range of reaction time is 5 - 10 hours, more preferably 6 - 8 hours, even more preferably 7 hours. The suggested range of reaction temperature is 50 °C - 70 °C, more preferably 60 °C. Samples were taken every 15 minutes. After the 3rdseparation step, the mixture was filtered using a pressurized filter unit and the solids were washed with pyridine. The liquid fractions were concentrated in vacuo and analyzed using ATR-FT-IR spectroscopy and Raman spectroscopy. After the 4thseparation step, no solids remained.

[0206] From table 3 of figure 18, it can be concluded that an accumulation of more than 80 % of each material, i.e. , MR7 and MR8, can be achieved in the corresponding thiolysis mixtures using low temperatures, i.e., the averaged content of MR7 in the liquid fraction after the 1stseparation step was 0.81 (mass fraction) and the content of MR8 in the liquid fraction after the 4thseparation step was 94 wt%. The ratio of MR8 to the total amount of PTU in solution was calculated by the ratio of the ester band to the PTU bands in comparison to the full conversion of materials. The conversion of MR8 was calculated using the integral of the ester band. The conversion of MR7 was calculated using the integral of the aromatic band in comparison to the full conversion. The line “depolymerization of swarf by gravimetry [%]” in table 3 refers to the amount (wt%) of depolymerized solids with respect to the initial amount of solids determined by weighing.

[0207] List of reference numerals

[0208] 100 method

[0209] SO obtaining information on a composition of the mixture S1 deriving instructions for carrying out the separation of the different materials

[0210] 52 shredding step

[0211] 53 drying step

[0212] 54 physical dissolution step

[0213] S4a first physical dissolution step S4b second physical dissolution step

[0214] 55 thiolysis step

[0215] 56 alcoholysis step

[0216] 57 handling of remaining materials 200 method

[0217] 520 pretreatment step

[0218] 521 1stthiolysis step

[0219] 522 2ndthiolysis step

Claims

1. Claims1 . A method (100) for separating different polymeric spectacle lens materials in a mixture comprising at least two different polymeric spectacle lens materials, characterized by separating at least one polymeric spectacle lens material of the at least two different polymeric spectacle lens materials by using their different physical behavior and / or chemical behavior, wherein the at least two different polymeric spectacle lens materials are selected from the group consisting of polyallyl carbonate, polyurea, polyurethane, polyurethane / polyurea, polycarbonate, polyepisulfide, and polythiourethane.

2. The method (100) as claimed in claim 1, characterized by comprising at least two steps selected from the group consisting of: a physical dissolution step (S4), a thiolysis step (S5), and an alcoholysis step (S6).

3. The method (100) as claimed in claim 2, characterized by carrying out the physical dissolution step (S4) before the thiolysis step (S5) and / or the alcoholysis step (S6), and / or by carrying out the thiolysis step (S5) before the alcoholysis step (S6).

4. The method (100) as claimed in claim 2 or 3, characterized by using in the thiolysis step (S5) a thiolysis reagent which is at least one selected from the group consisting of monothiols, dithiols, trithiols, and tetrathiols.

5. The method (100) as claimed in any one of claims 2 to 4, characterized by using in the thiolysis step (S5) a thiolysis reagent comprising at least one thiol, wherein the at least one thiol is identical to a thiol used for the synthesis of a polythiourethane material to be separated by thiolysis.

6. The method (100) as claimed in any one of claims 2 to 5, characterized in that the thiolysis step (S5) and / or the alcoholysis step (S6) uses a strong basic catalyst.

7. The method (100) as claimed in any one of claims 2 to 6, characterized in that the thiolysis step (S5) and / or the alcoholysis step (S6) uses a polar aprotic solvent.

8. The method (100) as claimed in any one of claims 2 to 7, characterized in that the mixture of the different polymeric spectacle lens materials comprises at least two different polythiourethane materials, and each of the at least two different polythiourethane materials are separated in the thiolysis step (S5) by carrying out the thiolysis step (S5) under time control and / or temperature control.

9. The method (100) as claimed in any one of claims 2 to 8, characterized by using in the physical dissolution step (S4) a solvent which is at least one selected from the group consisting of aliphatic hydrocarbons, chlorinated hydrocarbons, hydrocarbons containing at least one oxygen, sulfur and / or nitrogen heteroatom, dimethylformamide, dimethylacetamide, and pyridine.

10. The method (100) as claimed in any one of claims 1 to 9, characterized by further comprising: obtaining information on a composition of the mixture (SO), and deriving instructions for carrying out the separation of the different polymeric spectacle lens materials based on the obtained information (S1).1 1 . The method (100) as claimed in any one of claims 1 to 10, characterized by further comprising a shredding step (S2) of the mixture.

12. The method (100) as claimed in any one of claims 1 to 11 , characterized by further comprising a drying step (S3).

13. The method (100) as claimed in any one of claims 2 to 12, characterized by further comprising: producing a reaction product which is at least one selected from the group consisting of polythiourethanes, thiol-epoxy resins and reaction products of a thiolene reaction using a thiolysis product obtained from the thiolysis step (S5).

14. The method (100) as claimed in any one of claims 2 to 13,characterized by further comprising: producing a reaction product which is at least one selected from the group consisting of polyurethanes, epoxy resins and polyesters using an alcoholysis product obtained from the alcoholysis step (S6).

15. A method (200) for separating at least one polythiourethane from a mixture comprising at least two different polythiourethanes, characterized by separating the at least one polythiourethane material by thiolysis.

16. The method (200) as claimed in claim 15, characterized by using in thiolysis a thiolysis reagent which is at least one selected from the group consisting of monothiols, dithiols, trithiols, and tetrathiols.

17. The method (200) as claimed in claim 15 or 16, characterized by using in thiolysis a thiolysis reagent comprising at least one thiol, wherein the at least one thiol is identical to a thiol used for the synthesis of the at least one polythiourethane to be separated by thiolysis.

18. The method (200) as claimed in any one of claims 15 to 17, characterized by using a strong basic catalyst in thiolysis.

19. The method (200) as claimed in any one of claims 15 to 18, characterized by using a polar aprotic solvent in thiolysis.

20. The method (200) as claimed in any one of claims 15 to 19, characterized by carrying out thiolysis under time control and / or temperature control.21 . The method (200) as claimed in any one of claims 15 to 20, characterized in that the at least one polythiourethane is a spectacle lens material.

22. The method (200) as claimed in any one of claims 15 to 21, characterized in that the mixture comprising at least two different polythiourethanes further comprises at least one polymeric material selected from the group consisting of polyallyl carbonate, polyurea, polyurethane, polyurethane / polyurea, polycarbonate, polyepisulfide, and polythiourethane.

23. The method (200) as claimed in claim 22, characterized in that the at least one polymeric material is a spectacle lens material.

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