Process for recycling of polyurethane or polyisocyanurate foam

Abstract

In a first aspect, the invention is directed to a process for recycling of polyurethane or polyisocyanurate foam which comprises a phosphine oxide based flame retardant by depolymerization, thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant. A second aspect of the invention relates to a polyol composition (PC) obtained or obtainable from a glycolysis of the first aspect, a third aspect of the invention is directed to a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I), wherein the at least one component having OH group(s) comprises at least one structural carbamate element ····HN-C(=O)-O···. In a fourth aspect, the invention relates to the use of the polyol composition (PC) of the second aspect of the invention or of the polyol composition (PC) of the third aspect of the invention for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane rigid foam or a polyisocyanurate rigid foam. A sixth aspect of the invention is directed to a method for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane or polyisocyanurate rigid foam, the method comprising reacting the polyol composition (PC) of the second aspect of the invention or the polyol composition (PC) of the third aspect of the invention with an isocyanate composition and optionally with at least one further polyol.

Description

[0001] 240243W001

[0002] Process for recycling of polyurethane or polyisocyanurate foam

[0003] In a first aspect, the invention is directed to a process for recycling of polyurethane or polyisocyanurate foam which comprises a phosphine oxide based flame retardant by depolymerization, thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant. A second aspect of the invention relates to a polyol composition (PC) obtained or obtainable from the process of the first aspect, a third aspect of the invention is directed to a polyol composition (PC) comprising at least one component having OH group(s) and / or, preferably and, at least a part of the phosphine oxide based flame retardant of formula (I). In a fourth aspect, the invention relates to the use of the polyol composition (PC) of the second aspect of the invention or of the polyol composition (PC) of the third aspect of the invention for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane rigid foam or a polyisocyanurate rigid foam. A sixth aspect of the invention is directed to a method for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane or polyisocyanurate rigid foam, the method comprising reacting the polyol composition (PC) of the second aspect of the invention or the polyol composition (PC) of the third aspect of the invention with an isocyanate composition and optionally with at least one further polyol.

[0004] Recycling of polyurethane rigid foams or polyisocyanurate rigid foams, in particular chemical recycling, is an essential technology to advance towards a circular economy in the construction industry. Said recycling to valuable monomeric compounds and recovery of the additives however still remains challenging. It is known that generally, the polyol compound and amine can be recovered and recycled by glycolysis or hydrolysis but also by hydrogenation in the presence of a hydrogenation catalyst is known. For example, US 4,196,148 A describes a method for hydrolysis of a polyurethane foam and recovery of diamines and polyethers (or polyesters) from the hydrolysate carried out near atmospheric pressure and temperatures above 185 °C.

[0005] However, state-of-the-art polyurethane rigid foams as well as polyisocyanurate rigid foams contain flame retardants. From the known flame retardants, especially phosphorous containing compounds like tris(2-chloro-1 -methylethyl) phosphate (TCPP) and triethyl phosphate (TEP) were found to be not compatible with existing methods of chemical recycling such as glycolysis and hydrolysis. The presence of these phosphorous containing flame retardants interferes with the recycling process and inhibits the desired lysis reactions. Furthermore, the degradation of these phosphorus containing flame retardants, with view to a recycling of the polyol containing compositions obtained as lysis reaction products, diminishes it's flame retarding properties and the acidic degradation products deteriorate the foaming process once these polyol containing compositions are reused for preparation of new polyurethane rigid foams or polyisocyanurate rigid foams.

[0006] Another problem associated with the reuse of the obtained polyol containing compositions for preparation of new polyurethane rigid foams or polyisocyanurate rigid foams is their behavior when used, for example, in the production of sandwich panels via a double-belt process. The production of sandwich panels containing polyurethane foam via the double-belt process requires a thorough adjustment of the polymerization reactions. On the one hand, the reaction 240243W001

[0007] - 2 - mixture must fill the sandwich panel completely leaving no major cavities by sufficient foam expansion. On the other hand, any foam expansion after filling the space between the lower and upper layer will induce an anisotropy of the cells leading to a deterioration of the foam and panel properties. Furthermore, the reaction mixture must expand to the upper belt (contact time) before reaching its gel time to ensure satisfactory adhesion to the cover sheet. Hence, the post-expansion of polyurethane rigid foam after reaching its gel time is an unfavorable process. The post-expansion of polyurethanes can be evaluated by the needle height test, wherein a needle height as low as possible is desired.

[0008] Therefore, it was an object of the present invention to provide a process for depolymerization of a flame retardant containing polyurethane rigid foam or polyisocyanurate rigid foam, which results in polyol containing compositions not having or leading to the above identified disadvantages. Another problem associated therewith was thus the identification of polyurethane rigid foam and / or polyisocyanurate rigid foam, suitable for such a depolymerization reaction.

[0009] In a first aspect, the problem was solved by a process for recycling of polyurethane or polyisocyanurate foam comprising a) Providing a polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) and which comprises a phosphine oxide based flame retardant of formula (I) wherein R1, R2and R3are independently of each other selected from the group consisting of branched and unbranched C1 to C10 alkyl group and C6 to C12 aryl group; b) Depolymerization of the polyurethane or polyisocyanurate of the material provided in step a), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I).

[0010] It was surprisingly found that polyurethane or polyisocyanurate, especially polyurethane rigid foam or polyisocyanurate rigid foam, equipped with phosphine oxide based flame retardant of formula (I), can be depolymerized by means of chemolysis reactions. The phosphine oxide based flame retardant of formula (I) does surprisingly neither decompose during nor interfere with the depolymerization processes like glycolysis and hydrolysis and is therefore compatible with the lysis process. Furthermore, as indicated in more detail herein below, reuse of the polyol containing composition, obtained as lysis product, in the preparation of new polyurethane or polyisocyanurate, especially new polyurethane or polyisocyanurate rigid foam, is advantageous.

[0011] According to the present invention, a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I) is obtained in step b). Preferably, the polyol composition (PC) obtained in step b) comprises at least 40 weight-%, preferably at least 50 weight-%, 240243W001

[0012] - 3 - more preferably at least 60 weight-%, more preferably at least 65 weight-% of the phosphine oxide based flame retardant of formula (I), relative to the amount of the phosphine oxide based flame retardant of formula (I) in the polyurethane or polyisocyanurate material provided according to a) being 100 weight-%.

[0013] If one or more of the residues R1, R2, R3of the phosphine oxide based flame retardant of formula (I) comprise(s) a reactive functional group, especially a hydroxyl group, amino group, and / or thio group, the polyol composition (PC) obtained in step b) preferably comprises at the outmost the above-identified amounts, i.e. preferably at least 40 weight-%, more preferably at least 50 weight-%, more preferably at least 60 weight-%, more preferably at least 65 weight-% of the phosphine oxide based flame retardant of formula (I) are comprised in the polyol composition (PC) obtained in step b), relative to the amount of the phosphine oxide based flame retardant of formula (I) in the polyurethane or polyisocyanurate material provided according to a) being 100 weight-%.

[0014] If none of the residues R1, R2, R3of the phosphine oxide based flame retardant of formula (I) comprises a reactive functional group, especially a hydroxyl group, amino group, and / or thio group, the polyol composition (PC) obtained in step b) preferably comprises at the above-identified amounts, i.e. preferably at least 40 weight-%, more preferably at least 50 weight-%, more preferably at least 60 weight-%, more preferably at least 65 weight-%, but further also more preferably at least 90 weight-%, more preferably at least 94 weight-%, more preferably at least 96 weight-%, more preferably at least 97 weight-%, more preferably at least 98 weight-%, more preferably at least 99 weight-%, of the phosphine oxide based flame retardant of formula (I) are comprised in the polyol composition (PC) obtained in step b), relative to the amount of the phosphine oxide based flame retardant of formula (I) in the polyurethane or polyisocyanurate material provided according to a) being 100 weight-%.

[0015] Phosphine oxide based flame retardant

[0016] According to the present invention, a phosphine oxide based flame retardant of formula (I) wherein R1, R2and R3are independently of each other selected from the group consisting of branched and unbranched C1 to C10 alkyl group and C6 to C12 aryl group, is comprised in the polyurethane or polyisocyanurate material provided in step a). Preferably, a branched and unbranched C1 to C10 alkyl group is unsubstituted or substituted with a least one substituent selected from the group consisting of hydroxyl group, amino group, and thio group, more preferably unsubstituted or substituted with a least one hydroxyl group.

[0017] Preferably, a C6 to C12 aryl group is unsubstituted or substituted with at least one substituent selected from hydroxyl group, amino group, thio group and branched and unbranched C1 to C10 alkyl group, wherein a C6 to C12 aryl group is more preferably unsubstituted. 240243W001

[0018] - 4 -

[0019] In some embodiments, the residues R1, R2and R3are preferably independently of each other a branched or unbranched C1 to C5 alkyl group, wherein the branched or unbranched C1 to C5 alkyl group independently for each of R1, R2,R3is unsubstituted or substituted, more preferably unsubstituted or substituted with at least one hydroxyl group.

[0020] In some embodiments, the residues R1, R2and R3are preferably independently of each other a C6 aryl group, wherein each C6 aryl group is unsubstituted or substituted with at least one substituent selected from hydroxyl group, amino group, thio group and branched and unbranched C1 to C5 alkyl group, more preferably each C6 aryl group is unsubstituted.

[0021] Preferably, the phosphine oxide based flame retardant of formula (I) is selected from triphenylphosphine oxide (TPPO), isobutyl di(hydroxypropyl)phosphine oxide and mixtures of triphenylphosphine oxide and isobutyl di(hydrox- ypropyl)phosphine oxide.

[0022] Preferably, the polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) provided in step a) comprises in the range of from 0.1 to 50 weight-%, more preferably in the range of from 0.5 to 10 weight- % of phosphine oxide based flame retardant of formula (I), based on the total weight of the polyurethane or polyisocyanurate material being 100 weight-%.

[0023] Phosphorous ester-based flame retardants, halogen containing compounds

[0024] According to the present invention, a phosphine oxide based flame retardant of formula (I) as detailed above is comprised in the polyurethane or polyisocyanurate material provided in step a). Preferably, the polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) provided in step a) comprises less than 1 weight-% of a phosphorous ester-based flame retardant, based on the total weight of the polyurethane or polyisocyanurate material being 100 weight-%. Preferably, the phosphorous ester-based flame retardant is selected from the group consisting of tris(2-chloroethyl)phosphate, tris(chloroisopropyl)phosphate, tris(1,3-dichloro-2-propyl)phosphate, tris(2- ethylhexyl)phosphate, tricresylphosphate, tris-(2,3-dibromo)phosphate, tetrakis-(2-chlorethyl)-ethylenediphosphate, dimethylphosphonate, dimethylpropylphosphonate, diphenylcresylphosphate, triethylphosphate, diethyl (hydroxyme- thy l)phosphonate, resorcinol bis(diphenyl phosphate), and mixtures of two or more thereof.

[0025] According to the present invention, a phosphine oxide based flame retardant of formula (I) as detailed above is comprised in the polyurethane or polyisocyanurate material provided in step a). Preferably, the polyurethane or polyisocyanurate material is halogen-free. "Halogen-free” means that the material contains less than 0.2 weight-% of halogen, determined by combustion ion chromatography according to ASTM D7359-23 or determined by elementary analysis.

[0026] As commonly known state-of-the-art techniques allow a sorting of polymeric materials based on spectroscopic and / or spectrometric analysis, it is possible to identify and select suitable polyurethane or polyisocyanurate materials, which 240243W001

[0027] - 5 - do comprise phosphine oxide based flame retardant of formula (I) as detailed above but which do not contain >1 weight-% of a phosphorous ester-based flame retardant and / or which are halogen-free.

[0028] Polyurethane or polyisocyanurate material

[0029] According to the present invention, a polyurethane or polyisocyanurate material is provided in step a). Preferably, the polyurethane or polyisocyanurate material comprises or is a polyurethane or polyisocyanurate rigid foam.

[0030] In some embodiments, the polyurethane rigid foam is preferably an aromatic isocyanate-based polyurethane rigid foam, preferably a methylenedi(phenylisocyanate)-based polyurethane rigid foam, more preferably a PMDI-based polyurethane rigid foam.

[0031] In some embodiments, the polyisocyanurate rigid foam is preferably an aromatic isocyanate-based polyisocyanurate rigid foam, preferably a methylenedi(phenylisocyanate)-based polyisocyanurate rigid foam, more preferably a PMDI- based polyisocyanurate rigid foam.

[0032] Preferably, the polyurethane rigid foam or polyisocyanurate rigid foam, preferably the polyisocyanurate rigid foam, has an index >200. The "index” is defined as the excess of isocyanate over an equivalent reaction with all active H expressed as a percentage, i.e. isocyanate index = isocyanate equivalent I polyol equivalent.

[0033] According to the invention, a polyurethane or polyisocyanurate material is provided in step a), which is obtained from at least one polyol (P 1). Preferably, the polyol (P1) is selected from the group consisting of polyether polyol (p1 ), polyester polyol (p2), and mixtures of two or more thereof.

[0034] The polyol (P) is preferably selected from the group consisting of polyether polyols (p1 ), polyester polyols (p2) or mixtures thereof, preferably polyesterols (p2) or mixtures of polyetherols (p1) and polyesterols (p2). Preferably, polyetherols (p1) and polyesterols (p2) have a number-average molecular weight of 150 to 15,000 g / mol, preferably 150 to 5,000 g / mol and particularly preferably 200 to 2,000 g / mol. In addition to polyetherols and polyesterols, further compounds (p), for example, low molecular weight chain extenders and / or crosslinking agents known in polyurethane chemistry are optionally used. Preferably, these compounds (p) have a number-average molecular weight of 62 to 15,000 g / mol and / or have a number-average functionality of at least 1.7, particularly preferably at least 2. Preferably, the polyetherols (p1) and / or polyesterols (p2) have a number-average functionality of at least 1.7, more preferably of at least 2.0.

[0035] Preferably, the polyols (P) comprise at least one polyether polyol (p1) and / or at least one polyester polyol (p2), preferably at least one polyester polyol (p2), optionally in combination with at least one polyether polyol (p1 ). Preferably, the proportion by weight of polyetherol (p1) is 0 to 30% by weight, more preferably 0 to 20% by weight and in particular 1 to 15% by weight, and of polyesterol (p2) is preferably 70 to 100% by weight, more preferably 80 to 100% by 240243W001

[0036] - 6 - weight and in particular 85 to 99% by weight, in each case based on the total weight of polyetherol (p1) and polyesterol (p2). In the context of the present disclosure, the terms "polyester polyol” and “polyesterol” are synonymous, as are the terms "polyether polyol” and “polyetherol” .

[0037] The polyetherols (p1) are obtained by known methods, for example by anionic polymerization of alkylene oxides with the addition of at least one starter molecule containing 1 to 8, preferably 2 to 6 reactive hydrogen atoms bound, or a starter molecule mixture which contains 1 .5 to 8, preferably 2 to 6 reactive hydrogen atoms bound, averaged over all the starters present, in the presence of catalysts. If mixtures of starter molecules with different functionalities are used, fractional functionalities are preferably obtained.

[0038] Influences on the functionality, for example due to side reactions, are not taken into account in the nominal functionality. Alkali hydroxides, such as sodium or potassium hydroxide, or alkali alcoholates, such as sodium methylate, sodium or potassium ethylate or potassium isopropylate, or Lewis acids, such as antimony pentachloride, boron trifluoride etherate or bleaching earth, are preferably used as catalysts in cationic polymerization. Aminic alkoxylation catalysts such as dimethylethanolamine (DMEOA), imidazole and imidazole derivatives can also be used. Furthermore, double metal cyanide compounds, so-called DMC catalysts, can also be used as catalysts.

[0039] Preferably, the alkylene oxides used are one or more compounds having 2 to 4 carbon atoms in the alkylene radical, such as tetrahydrofuran, 1 ,2-propylene oxide, ethylene oxide, 1,2- or 2,3-butylene oxide, in each case alone or in the form of mixtures. Preferably, ethylene oxide and / or 1 ,2-propylene oxide are used, particularly preferably ethylene oxide.

[0040] The starter molecules used are compounds containing hydroxyl groups or amine groups, for example ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1 ,3-propanediol, bisphenol-A, bisphenol-F, glycerol, trimethylolpropane, pentaerythritol, sugar derivatives such as sucrose, hexitol derivatives such as sorbitol, methylamine, ethylamine, isopropylamine, butylamine, benzylamine, aniline, toluidine, toluene diamine (TDA), naphthylamine, ethylenediamine, methylenedianiline, 2,2'-diaminodiphenylmethane (2,2-MDA) 2,4'-diaminodiphenylmethane (2,4-MDA), 4,4'-diaminodiphenylmethane (4,4-MDA), diethylenetriamine, 4, 4'-methylenedianiline, 1 ,3, -propanediamine, 1 ,6-hex- anediamine, ethanolamine, diethanolamine, triethanolamine and other di- or polyhydric alcohols or mono- or polyhydric amines or water. Since the highly functional compounds are often present in solid form under the usual reaction conditions of alkoxylation, it is common practice to alkoxy late them together with co-initiators. Suitable co-initiators include water, polyfunctional lower alcohols, e.g. glycerol, trimethylolpropane, pentaerythritol, diethylene glycol, ethylene glycol, propylene glycol and their homologs. Other possible co-initiators include organic fatty acids or monofunctional fatty alcohols, fatty acid monoesters or fatty acid methyl esters such as oleic acid, stearic acid, oleic acid methyl esters, stearic acid methyl esters or biodiesel, which are used to improve blowing agent solubility in the production of rigid polyisocyanurate foams. 240243W001

[0041] - 7 -

[0042] Preferred starter molecules for preparing the polyether polyols (p1) are sorbitol, sucrose, ethylenediamine, TDA, trimethylolpropane, pentaerythritol, glycerol, biodiesel, nonylphenol, ethylene glycol and diethylene glycol. Further preferred starter molecules are all starters or starter mixtures with an average total functionality of < 3, particularly preferred glycerol, trimethylolpropane, biodiesel, nonylphenol, ethylene glycol, diethylene glycol, propylene glycol and bisphenol-A, especially ethylene glycol, diethylene glycol and glycerol.

[0043] The polyether polyols used in component (p1) preferably have an average functionality of from 1.5 to 6 and in particular from 2.0 to 4.0 and number-average molecular weights of preferably from 150 to 3000, particularly preferably from 150 to 1500 and in particular from 250 to 800 g / mol. The OH number of the polyether polyols of component (p1) is preferably from 1200 to 50, preferably from 600 to 100 and in particular from 300 to 150 mg KOH / g.

[0044] Polyester polyols (p2) are preferably prepared from organic dicarboxylic acids with 2 to 12 carbon atoms, preferably aromatic, or mixtures of aromatic and aliphatic dicarboxylic acids and polyhydric alcohols, preferably diols, with 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms.

[0045] The following dicarboxylic acids are particularly suitable: succinic acid, glutaric acid, adipic acid, cork acid, azelaic acid, sebacic acid, decandicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid. The dicarboxylic acids are preferably used both individually and in mixtures. Instead of the free dicarboxylic acids, the corresponding dicarboxylic acid derivatives, such as dicarboxylic acid esters of alcohols with 1 to 4 carbon atoms or dicarboxylic acid anhydrides, can also be used. The aromatic dicarboxylic acids or acid derivatives preferably used are phthalic acid, phthalic anhydride, terephthalic acid and / or isophthalic acid in a mixture or alone. The aliphatic dicarboxylic acids preferably used are dicarboxylic acid mixtures of succinic, glutaric and adipic acid in quantitative ratios of, for example, 20 to 35 : 35 to 50 : 20 to 32 parts by weight, and in particular adipic acid. Particularly preferred polyesterols (p2) are exclusively those obtained by using exclusively aromatic dicarboxylic acid or derivatives thereof. Preferably, at least one compound selected from the group consisting of terephthalic acid, dimethyl terephthalate (DMT), polyethylene terephthalate (PET), phthalic acid, phthalic anhydride (PSA) and isophthalic acid is used as the aromatic dicarboxylic acid, particularly preferably at least one compound from the group consisting of terephthalic acid, di-methyl terephthalate (DMT), polyethylene terephthalate (PET) and phthalic anhydride (PSA) and in particular phthalic acid and / or phthalic anhydride.

[0046] Examples of polyhydric alcohols, in particular diols, are: monoethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,2- or 1 ,3-propanediol, dipropylene glycol, polyopropylene glycol, 1 ,4-butanediol, 1,5-pentane- diol, 1 ,6-hexanediol, 1 ,10-decanediol, glycerol, trimethylolpropane and pentaerythritol, as well as alkoxylates of the same starters. Preferably used are monoethylene glycol, diethylene glycol, triethylene glycol, 1,2- or 1 ,3-propanediol, dipropylene glycol, as well as ethoxylates of the same starters, for example ethoxylated glycerol, or mixtures of at least one of the diols mentioned. In particular, monoethylene glycol, diethylene glycol, glycerol and ethoxylates of the same starters, or mixtures of at least two of the diols mentioned, especially diethylene glycol, are used. Polyester 240243W001

[0047] - 8 - polyols from lactones, e.g. epsilon-caprolactone or hydroxycarboxylic acids, e.g. omega-hydroxycaproic acid, can also be used.

[0048] To prepare the polyester polyols (p2), the aliphatic and aromatic polycarboxylic acids and / or derivatives and polyhydric alcohols are preferably polycondensed in the melt at temperatures of 150 to 280 °C, preferably 180 to 260 °C, preferably in the presence of esterification catalysts, expediently in an atmosphere of inert gas such as nitrogen, if necessary under reduced pressure, to the desired acid number, which is advantageously less than 10, preferably less than 2. Suitable esterification catalysts include, for example, iron, cadmium, cobalt, lead, zinc, antimony, magnesium, titanium and tin catalysts in the form of metals, metal oxides or metal salts. However, the polycondensation can also be carried out in the liquid phase in the presence of diluents and / or entraining agents, such as benzene, toluene, xylene or chlorobenzene, for azeotropic distillation of the condensation water.

[0049] To prepare the polyester polyols (p2), the organic polycarboxylic acids and / or derivatives and polyhydric alcohols are advantageously polycondensed in a molar ratio of 1 : 1 to 2.2, preferably 1 : 1.05 to 2.1 and particularly preferably 1 : 1.1 to 2.0.

[0050] The polyester polyols (p2) obtained generally have a number-average molecular weight of 200 to 3000, preferably 300 to 1000 and in particular 400 to 800.

[0051] The polyurethane or polyisocyanurate to be depolymerized is based on the above describes polyol (P) and a polyisocyanate, wherein all polyisocyanates known for the production of polyurethanes are comprised. Preferably, the polyisocyanate is selected from the group of aliphatic, cycloaliphatic and aromatic divalent or polyvalent isocyanates known from the prior art as well as any mixtures thereof. Examples are 2,2'-, 2,4'- and 4,4'-dipheny Imethane diisocyanate, the mixtures of monomeric diphenylmethane diisocyanates and higher-core homologues of diphenylmethane diisocyanate (polymer MDI), isophorone diisocyanate (IPDI) or oligomers thereof, 2,4- or 2,6-toluene diisocyanate (TDI) or mixtures thereof, tetramethylene diisocyanate or oligomers thereof, hexamethylene diisocyanate (HDI) or oligomers thereof, naphthylene diisocyanate (NDI) or mixtures thereof. These preferably contain toluene diisocyanate isomers (TDI isomers) and isomers of methyl diphenylene diisocyanate and its higher-nuclear homologs (referred to as MDI). Particularly preferred as an aromatic polyisocyanate is a mixture comprising 2,4'-MDI, 4,4'-MDI and higher- nuclear homologs of MDI (hereinafter referred to as "polymer MDI” or “PMDI”). PMDI preferably has a structure as shown below, wherein n is zero or a number in the range of from 1 to 5.

[0052] Modified isocyanates, such as isocyanates formed by incorporating groups starting from isocyanate groups in which polyisocyanates are formed, can also be used. Examples of such groups are allophanate, carbodiimide, uretonimine, 240243W001

[0053] - 9 - isocyanurate, urea and biuret groups. In a preferred embodiment, the proportion of 2,4'-diphenylmethane diisocyanate is preferably 5 to 30% by weight and of 4,4'-dipheny Imethane diisocyanate is preferably 40 to 80% by weight, in each case based on the total weight of the aromatic polyisocyanates (a). In a preferred embodiment, the proportion of higher-core homologs of the diphenylmethane diisocyanate is 3 to 30% by weight, particularly preferably 5 to 25% by weight.

[0054] The aromatic polyisocyanates can also be used in the form of prepolymers. For this purpose, the aromatic polyisocyanates described above are reacted in excess with compounds containing compounds which are reactive towards isocyanates. Preferably, the compounds mentioned under (a) with at least two isocyanate-reactive hydrogen atoms are used as isocyanate-reactive compounds. If isocyanate prepolymers are used as aromatic isocyanates, they preferably have an NCO content of 16 to 31% by weight.

[0055] For preparing the polyurethane or polyisocyanurate, polyol component and polyisocyanate component are preferably mixed at a temperature in the range between 15 and 120 °C, preferably 20 and 80 °C. Further components used for preparing the polyurethane or polyisocyanurate are selected from the group consisting of catalyst, foaming agent, auxiliary, additive and mixtures of two or more thereof. These further components are known to the skilled person and are described, for example, in WO 2024 / 110395 A1 as well as in Kunststoffhandbuch (Plastics Handbook), Volume 7, Polyurethanes, edited by Gunter Oertel, Carl-Hanser-Verlag, Munich, 3rd edition 1993.

[0056] Step b)

[0057] According to the invention, depolymerization of the polyurethane or polyisocyanurate of the material provided in step a) is done in step b), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I).

[0058] Preferably, the depolymerization according to step b) is carried out by a method selected from the group consisting of glycolysis, hydrolysis, alcoholysis, aminolysis, and ammonolysis, more preferably the depolymerization according to step b) is carried out by glycolysis or by hydrolysis. These depolymerization methods are in principle known to the person skilled in the art.

[0059] Preferably, step (b) comprises b.1 ) optionally size reduction of the polyurethane or polyisocyanurate material provided in step a), thereby obtaining a size reduced polyurethane or polyisocyanurate material; b.2) Depolymerization of the polyurethane or polyisocyanurate of the material provided in step a) or of the size reduced material obtained in b.1 ), which is obtained from at least one polyol (P1) and at least one isocyanate (11), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s), at least a part of the phosphine oxide based flame retardant of formula (I), and optionally at least one amine component or amine derivative from the isocyanate 11 . 240243W001

[0060] - 10 -

[0061] Size reduction in step b.1) is preferably done mechanically, more preferably by a method selected from the group consisting of shredding, tearing, cutting, grinding and mixed forms of two or more thereof. Step b.1 ) is conducted in order to reduce the material's size to an appropriate level for further processing and in order to open up the foam cells to release any foaming agent captured therein before further processing.

[0062] In some embodiments, it is also preferred to conduct prior to step a) a sorting step x), wherein polymeric material is sorted and selected so that a suitable polyurethane or polyisocyanurate material, which do comprise phosphine oxide based flame retardant of formula (I) as detailed above but which do not contain >1 weight-% of a phosphorous ester- based flame retardant and / or which are halogen-free is provided in step a). Suitable methods allowing a sorting of polymeric materials based on spectroscopy and / or spectrometry analysis are in principle known to the person skilled in the art.

[0063] Step b) - Glycolysis

[0064] In some embodiments of the process, the depolymerization according to step b) or b.2) is preferably carried out by glycolysis. Glycolysis is as such known to the skilled person.

[0065] Glycolysis in the context of the present invention is preferably carried out with at least one glycol selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, oligomer thereof, polymer thereof and mixtures of two or more thereof. An oligomer comprises in the range of from 2 to 10 repeating units based on the respective monomer, a polymer comprises > 10 repeating units based on the respective monomer.

[0066] According to the invention, depolymerization of the polyurethane or polyisocyanurate of the material provided in step a) is done in step b) or b.2), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I).

[0067] In these embodiments where depolymerization in step b) or b.2) is done by glycolysis, the at least one component having OH group(s) comprised in the polyol composition (PC) obtained in b) comprises at least one polycarbamatpol- yol, which is based on the polyisocyanate residue comprised in the polyurethane or polyisocyanurate of the material provided in step a) and the at least one glycol used for glycolysis. The polyol composition (PC) preferably further comprises a remainder of any polyetherpolyol (p1) and / or of any polyester polyol (p2) comprised in the polyurethane or polyisocyanurate of the material provided in step a). The remainder of a polyester polyol (p2) may comprise the organic polycarboxylic acid and / or derivative thereof and polyhydric alcohol as used for the preparation of the polyurethane or polyisocyanurate of the material provided in step a). In other words: Glycolysis of a PIR foam, which is based on a polyesterol results in transesterification with the glycol used for glycolysis. If, for example, a polyesterpol- 240243W001

[0068] - 11 - yol based on phthalic anhydride (PSA) and diethyleneglycol (DEG) had been the basis of the PIR foam with, for example, 4 repeating units, glycolysis with DEG yields a PSA-DEG ester with fewer repeating units and / or a lower molecular weight. In principle, free glycols, the original polyol(s) and carbamate(s) of the glycol or mixed carbamates that still contain polyol residues can be retained in the glycolysis polyol.

[0069] Preferably, glycolysis in step b) or b.2) is carried out in the presence of a component selected from the group consisting of catalyst, deamination agent, additive and mixtures of two or more thereof. Preferably, the catalyst comprises a metal containing catalyst, preferably selected from the group consisting of titanium alkoxide, alkali earth salt, alkaline earth salt and mixtures of two or more thereof, wherein the salts are preferably selected from the group consisting of oxide, hydroxide, carbonate, hydrogen carbonate, phosphate and mixtures of two or more thereof.

[0070] Preferably, the deamination agent is selected from the group consisting of aldehyde, epoxide, isocyanate, anhydride and mixtures of two or more thereof; and / or the additive is preferably selected from the group consisting of carboxylic acid, carboxylic acid ester, plant oil, oil and mixtures of two or more thereof.

[0071] Preferably, the glycolysis in step b) or b.2) is carried out with a mass based ratio glycol (mgiyCOi) to polyurethane or polyisocyanurate (mpu, PIR) in the range of from 1 :5 to 5:1 , preferably in the range of from 1 :2 to 2:1 , more preferably in the range of from 1 :0.8 to 2:1 , more preferably in the range of from 1 : 1 to 1.5:1.

[0072] Preferably, the glycolysis is carried out in step b) or b.2) at a temperature in the range of from 100°C to a temperature below the boiling point of the glycol, preferably in the range of from 150°C to below the boiling point of the glycol, more preferably at a temperature in the range of from 180 to 220°C.

[0073] Glycolysis in step b) or b.2) is preferably carried out continuously, discontinuously (batch wise) or semi-batch-wise.

[0074] Step b) - Hydrolysis

[0075] In some embodiments, the depolymerization according to step b) or b.2) is preferably carried out in the presence of water by hydrolysis, wherein hydrolysis more preferably is a method selected from the group consisting of hydrolysis, hydroalcoholysis, hydroaminolysis, hydroammonolysis and mixtures of two or more thereof.

[0076] Hydrolysis is preferably carried out in the presence of a catalyst, more preferably a basic catalyst, more preferably a basic catalyst selected from the group consisting of alkali metal hydroxide, amine (such as pyridine, triethylenediamine, MDA, or TDA) and mixtures of two or more thereof.

[0077] According to the invention, depolymerization of the polyurethane or polyisocyanurate of the material provided in step a) is done in step b) or b.2), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I). 240243W001

[0078] - 12 -

[0079] In these embodiments where depolymerization in step b) or b.2) is done by hydrolysis, the at least one component having OH group(s) comprised in the polyol composition (PC) obtained in step b) or b.2) comprises at least one remainder of any polyetherpolyol (p1) and / or of any polyester polyol (p2) comprised in the polyurethane or polyisocy- anurate of the material provided in step a).

[0080] The remainder of any polyetherpolyol (p1) may comprise the polyetherpolyol (p1 ). The remainder of a polyester polyol (p2) may comprise the organic polycarboxylic acid and / or derivative thereof and polyhydric alcohol as used for the preparation of the polyurethane or polyisocyanurate of the material provided in step a).

[0081] Preferably, hydrolysis is carried out with a molar based ratio water (nwater) to the sum of urethane groups and urea groups (nu) in the polyurethane or to the sum of urethane groups and urea groups and the threefold amount of isocy- anurate groups (nu) in the polyisocyanurate in the range of from 1 :1 to 1000:1, more preferably in the range of from 1.5:1 to 100:1, more preferably in the range of from 2:1 to 50:1.

[0082] Hydrolysis is preferably carried out continuously, discontinuously (batch wise) or semi-batch-wise.

[0083] Hydroal koholysis

[0084] In some embodiments, hydrolysis in step b) or b.2) is preferably carried out in the presence of an alcohol compound (hydroalkoholysis), more preferably selected from the group consisting of monovalent alcohol, polyvalent alcohol and mixture thereof, more preferably a glycol selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, oligomer thereof, polymer thereof and mixtures of two or more thereof (hydroglycolysis).

[0085] Hydroaminolysis

[0086] In some embodiments, hydrolysis in step b) or b.2) is preferably carried out in the presence of an amine compound, preferably selected from the group consisting of ammonia, aliphatic diamine, aromatic diamine (such as TDA or PMDA), polyamine alkanol amines and mixtures of two or more thereof (hydroaminolysis).

[0087] Preferably, hydrolysis, especially hydroaminolysis, in step b) or b.2) is carried out in the presence of ammonia (NH3), wherein hydrolysis especially hydroaminolysis, is preferably carried out with a molar based ratio ammonia (UNHS) to the sum of urethane groups und urea groups (nu) in the polyurethane or polyisocyanurate in the range of from 1 :1 to 1000:1, more preferably in the range of from 1.5:1 to 100:1, more preferably in the range of from 2:1 to 50:1.

[0088] Hydrolysis especially hydroaminolysis, is preferably carried out in the presence of a solvent, more preferably an organic solvent, more preferably an aromatic organic solvent, more preferably toluene. 240243W001

[0089] - 13 -

[0090] Hydrolysis especially hydroaminolysis, is preferably carried out under autogenous pressure, more preferably in a closed vessel, more preferably in an autoclave.

[0091] Hydrolysis especially hydroaminolysis, is preferably carried out at a temperature of more than 150°C, preferably in the range of from 150 to 400°C, more preferably in the range of from 200 to 300°C.

[0092] 2ndaspect - Polyol composition (product-by-process)

[0093] A second aspect of the invention is directed to a polyol composition (PC) obtained or obtainable from the process of the first aspect of the invention as described herein above. Preferably, the polyol composition (PC) is obtained or obtainable from a glycolyis according to the first aspect of the invention as described herein above.

[0094] Preferably, the polyol composition (PC) comprises at least one component having OH group(s). Components having OH group(s) formed due to the process of the first aspect of the invention as described herein above are at least partially the same or comparable poylols as used in the synthesis of the polyurethane or polyisocyanurate. Furthermore, at least partially one or more component(s) having OH group(s) are formed in the process, especially when glycolysis is carried out, which are reaction products of the glycol (s) used for glycolysis and the remainder of the polyisocya- nate(s) used in the synthesis of the polyurethane or polyisocyanurate. Preferably, a carbamate bond is formed between the glycol(s) and the remainder of the polyisocyanate(s). For example, if a polyurethane material based on a polyether polyol and PMDI is subjected to a glycolysis with diethylene glycol as glycol according to the first aspect of the invention as described herein above, at least a part of polyether polyol is set free but also a polyurethane polyol is at least partially formed, which has formula (X) shown below and which contains three structural carbamate elements ■ ■ ■ ■ HN-C(=O)-O- ■ ■, wherein the dotted bond (■ ■ ■) on the left and on the right side respectively represents the bond to the respective neighboring atom:

[0095] (X)

[0096] Alternatively, if a polyisocyanurate material based on polyester polyol(s) and PMDI is subjected to a glycolysis with diethylene glycol as glycol according to the first aspect of the invention as described herein above, at least a part of polyester polyol(s) is / are set free but also a polyurethane polyol is at least partially formed, which has formula (X) shown above and which contains three structural carbamate elements ■ ■ ■ ■ HN-C(=0)-O" . 240243W001

[0097] - 14 -

[0098] Preferably, the at least one structural carbamate element ■ ■ ■ ■ HN-C(=O)-O- - - constitutes at least 0.1 weight-%, preferably at least 0.5 weight-%, more preferably at least 1 .0 weight-%, more preferably at least 1 .5 weight-% of the polyol composition (PC), based on the total weight of the polyol composition being 100 weight-%. Preferably, the at least one structural carbamate element ■ ■ ■ -HN-C(=O)-O- ■ ■ constitutes at most 24 weight-%, preferably at most 21 weight- %, more preferably at most 18 weight-%, more preferably at most 15 weight-%, more preferably at most 12 weight-% of the polyol composition (PC), based on the total weight of the polyol composition being 100 weight-%.

[0099] Preferably, the at least one structural carbamate element ■ ■ ■ ■ HN-C(=O)-O- ■ ■ is identified and quantitatively determined by13C-NMR spectroscopy using a suitable internal reference such as for example dimethyl terephthalate (CAS: 120-61-6) or 1 ,3,5-trimethoxy benzene (CAS: 621-23-8). The at least one structural carbamate element ■ ■ ■ ■HN-C(=O)-O- ■ ■ is quantified by comparing the peak integral of the carbonyl carbon shift in a quantitative13C- NMR measurement with the peak of the respective internal reference, preferably determined according to Reference Example 5.

[0100] Preferably, the polyol composition (PC) comprises at least a part of the phosphine oxide based flame retardant of formula (I).

[0101] All details, embodiments described herein above with respect to the first aspect of the invention also apply to the second aspect of the invention.

[0102] 3rdaspect - Polyol composition

[0103] A third aspect of the invention is directed to a polyol composition (PC) comprising at least one component having OH group(s) and / or, preferably and, at least a part of the phosphine oxide based flame retardant of formula (I).

[0104] All details, embodiments described herein above with respect to the first aspect of the invention or with respect to the second aspect of the invention also apply to the third aspect of the invention.

[0105] 4thaspect - Use

[0106] A fourth aspect of the invention is directed to a use of the polyol composition (PC) of the second aspect of the invention as described herein above or of the polyol composition (PC) of the third aspect of the invention as described herein above for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane rigid foam or a polyisocyanurate rigid foam. 240243W001

[0107] - 15 -

[0108] All details, embodiments described herein above with respect to the first aspect of the invention or with respect to the second aspect of the invention or with respect to the third aspect of the invention also apply to the fourth aspect of the invention.

[0109] 5thaspect - Method for preparation of a polyurethane or polyisocyanurate material

[0110] A fifth aspect of the invention is directed to a method for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane or polyisocyanurate rigid foam, the method comprising reacting the polyol composition (PC) of the second aspect of the invention as described herein above or the polyol composition (PC) of the third aspect of the invention as described herein above with an isocyanate composition and optionally with at least one further polyol. Preferably, the isocyanate composition comprises at least one diisocyanate. Preferably, the at least one further polyol is selected from the group of polyesterpolyol and polyetherpolyol.

[0111] All details, embodiments described herein above with respect to the first aspect of the invention or with respect to the second aspect of the invention or with respect to the third aspect of the invention with respect to the fourth aspect of the invention also apply to the fifth aspect of the invention.

[0112] It was surprisingly found that using the respective polyol composition (PC) for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane or polyisocyanurate rigid foam, presumably due to the presence of the phosphine oxide based flame retardant of formula (I) in the a polyol composition (PC) results in polyurethane rigid foams or polyisocyanurate rigid foams having improved flame retarding properties. It was also found that polyurethane rigid foams or polyisocyanurate rigid foams obtained from the polyol composition (PC) have a lower heat release rate at 180 s to 360 s in the cone calorimeter test compared to polyurethane or polyisocyanurate rigid foams obtained from polyol containing compositions obtained from depolymerization of polyurethane or polyisocyanurate rigid foams, which contain phosphorous ester-based flame retardants such as TCPP. Surprisingly, the use of the inventive polyol composition (PC) [which comprises a part of the phosphine oxide based flame retardant of formula (I)] also leads to lower needle heights compared to polyurethane or polyisocyanurate rigid foams obtained from polyol containing compositions obtained from depolymerization of polyurethane or polyisocyanurate rigid foams, which contain phosphorous ester-based flame retardants such as TCPP.

[0113] The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The process of any one of embodiments 1 to 4", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The process of any one of embodiments 1, 2, 3 and 4". Further, it is explicitly noted that the following set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention. 240243W001

[0114] - 16 -

[0115] 1 . A process for recycling of polyurethane or polyisocyanurate foam comprising a) Providing a polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) and which comprises a phosphine oxide based flame retardant of formula (I) wherein R1, R2and R3are independently of each other selected from the group consisting of branched and unbranched 01 to C10 alkyl group and C6 to C12 aryl group; b) Depolymerization of the polyurethane or polyisocyanurate of the material provided in step a), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I).

[0116] 2. The process according to embodiment 1, wherein the polyol composition (PC) obtained in step b) comprises at least 40 weight-%, preferably at least 50 weight-%, more preferably at least 60 weight-%, more preferably at least 65 weight-%, of the phosphine oxide based flame retardant of formula (I), relative to the amount of the phosphine oxide based flame retardant of formula (I) in the polyurethane or polyisocyanurate material provided according to a) being 100 weight-%.

[0117] 3. The process of embodiment 1 or 2, wherein a branched and unbranched C1 to C10 alkyl group is unsubstituted or substituted with a least one substituent selected from the group consisting of hydroxyl group, amino group, and thio group, preferably unsubstituted or substituted with a least one hydroxyl group.

[0118] 4. The process of any one of embodiments 1 to 3, wherein a C6 to 012 aryl group is unsubstituted or substituted with at least one substituent selected from hydroxyl group, amino group, thio group and branched and unbranched 01 to C10 alkyl group, wherein a 06 to 012 aryl group is preferably unsubstituted.

[0119] 5. The process of any one of embodiments 1 to 4, wherein R1, R2and R3are independently of each other a branched or unbranched 01 to 05 alkyl group, wherein the branched or unbranched 01 to 05 alkyl group independently for each of R1, R2,R3is unsubstituted or substituted, preferably unsubstituted or substituted with at least one hydroxyl group.

[0120] 6. The process of any one of embodiments 1 to 5, wherein R1, R2and R3are independently of each other a 06 aryl group, wherein each 06 aryl group is unsubstituted or substituted with at least one substituent selected from hydroxyl group, amino group, thio group and branched and unbranched 01 to 05 alkyl group, preferably each 06 aryl group is unsubstituted. 240243W001

[0121] - 17 -

[0122] 7. The process of any one of embodiments 1 to 6, wherein the phosphine oxide based flame retardant of formula (I) is selected from triphenylphosphine oxide (TPPO), isobutyl di(hydroxypropyl)phosphine oxide and mixtures of triphenylphosphine oxide and isobutyl di(hydroxypropyl)phosphine oxide.

[0123] 8. The process of any one of embodiments 1 to 7, wherein the polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) provided in step a) comprises in the range of from 0.1 to 50 weight- %, preferably in the range of from 0.5 to 10 weight- % of phosphine oxide based flame retardant of formula (I), based on the total weight of the polyurethane or polyisocyanurate material being 100 weight-%.

[0124] 9. The process of any one of embodiments 1 to 8, wherein the polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) provided in step a) comprises less than 1 weight-% of a phosphorous ester-based flame retardant, based on the total weight of the polyurethane or polyisocyanurate material being 100 weight-%.

[0125] 10. The process according to embodiment 9, wherein the phosphorous ester-based flame retardant is selected from the group consisting of tris(2-chloroethyl)phosphate, tris(chloroisopropyl)phosphate, tris(1 ,3-dichloro-2- propyl)phosphate, tris(2-ethylhexyl)phosphate, tricresylphosphate, tris-(2,3-dibromo)phosphate, tetrakis-(2- chlorethyl)-ethylenediphosphate, dimethylphosphonate, dimethylpropylphosphonate, diphenylcresylphosphate, triethylphosphate, diethyl (hydroxymethyl)phosphonate, resorcinol bis(diphenyl phosphate), and mixtures of two or more thereof.

[0126] 11 . The process according to any one of embodiments 1 to 10, wherein the polyurethane or polyisocyanurate material is halogen-free.

[0127] 12. The process according to any one of embodiments 1 to 11, wherein the polyurethane or polyisocyanurate material is a polyurethane or polyisocyanurate rigid foam.

[0128] 13. The process according to embodiments 12, wherein polyurethane rigid foam is an aromatic isocyanate-based polyurethane rigid foam, preferably a methylenedi (phenylisocyanate)-based polyurethane rigid foam, more preferably a PMDI-based polyurethane rigid foam.

[0129] 14. The process according to embodiments 12, wherein polyisocyanurate rigid foam is an aromatic isocyanatebased polyisocyanurate rigid foam, preferably a methylenedi(phenylisocyanate)-based polyisocyanurate rigid foam, more preferably a PMDI-based polyisocyanurate rigid foam.

[0130] 15. The process according to any one of embodiments 12 to 14, wherein the polyurethane rigid foam or polyisocyanurate rigid foam, preferably the polyisocyanurate rigid foam, has an index >200. 240243W001

[0131] - 18 -

[0132] 16. The process according to any one of embodiments 1 to 15, wherein the polyol (P1) is selected from the group consisting of polyether polyol (p1 ), polyester polyol (p2), and mixtures of two or more thereof.

[0133] 17. The process according to any one of embodiments 1 to 16, wherein the depolymerization according to step b) is carried out by a method selected from the group consisting of glycolysis, hydrolysis, alcoholysis, aminolysis, and ammonolysis, preferably glycolysis or hydrolysis.

[0134] 18. The process according to embodiment 17, wherein step (b) comprises b.1 ) optionally size reduction of the polyurethane or polyisocyanurate material provided in step a), thereby obtaining a size reduced polyurethane or polyisocyanurate material; b.2) Depolymerization of the polyurethane or polyisocyanurate of the material provided in step a) or of the size reduced material obtained in b.1 ), which is obtained from at least one polyol (P1) and at least one isocyanate (11), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s), at least a part of the phosphine oxide based flame retardant of formula (I), and optionally at least one amine component or amine derivative from the isocyanate 11 .

[0135] 19. The process according embodiment 17 or 18, wherein the depolymerization according to step b) or b.2) is carried out by glycolysis.

[0136] 20. The process according embodiment 19, wherein glycolysis is carried out with at least one glycol selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, oligomer thereof, polymer thereof and mixtures of two or more thereof.

[0137] 21. The process according embodiment 19 or 20, wherein the at least one component having OH group(s) comprised in the polyol composition (PC) obtained in b) comprises at least one polycarbamatpolyol, which is based on the polyisocyanate residue comprised in the polyurethane or polyisocyanurate of the material provided in step a) and the at least one glycol used for glycolysis.

[0138] 22. The process according to any one of embodiments 19 to 21 , wherein glycolysis is carried out in the presence of a component selected from the group consisting of catalyst, deamination agent, additive and mixtures of two or more thereof.

[0139] 23 The process according to embodiment 22, wherein the catalyst comprises a metal containing catalyst, preferably selected from the group consisting of titanium alkoxide, alkali earth salt, alkaline earth salt and mixtures of two or more thereof, wherein the salts are preferably selected from the group consisting of oxide, hydroxide, carbonate, hydrogen carbonate, phosphate and mixtures of two or more thereof. 240243W001

[0140] - 19 -

[0141] 24. The process according to embodiment 22 or 23, wherein the deamination agent is preferably selected from the group consisting of aldehyde, epoxide, isocyanate, anhydride and mixtures of two or more thereof; and / or the additive is preferably selected from the group consisting of carboxylic acid, carboxylic acid ester, plant oil, oil and mixtures of two or more thereof.

[0142] 25. The process according to any one of embodiments 19 to 24, wherein glycolysis is carried out with a mass based ratio glycol (mgiycoi) to polyurethane or polyisocyanurate (mpu, PIR) in the range of from 1 :5 to 5:1, preferably in the range of from 1 :2 to 2:1, more preferably in the range of from 1:0.8 to 2:1, more preferably in the range of from 1 :1 to 1.5:1.

[0143] 26. The process according to any one of embodiments 19 to 25, wherein glycolysis is carried out at a temperature in the range of from 100°C to a temperature below the boiling point of the glycol, preferably in the range of from 150°C to below the boiling point of the glycol, more preferably at a temperature in the range of from 180 to 220°C.

[0144] 27. The process according to any one of embodiments 19 to 26, wherein glycolysis is carried out continuously, discontinuously (batch wise) or semi-batch-wise.

[0145] 28. The process according to embodiment 17 or 18, wherein the depolymerization according to step b) or b.2) is carried out in the presence of water by hydrolysis, wherein hydrolysis preferably is a method selected from the group consisting of hydrolysis, hydroalcoholysis, hydroaminolysis, hydroammonolysis and mixtures of two or more thereof.

[0146] 29. The process according to embodiment 28, wherein the at least one component having OH group(s) comprised in the polyol composition (PC) obtained in b) comprises at least one remainder of any polyetherpolyol (p1) and / or of any polyester polyol (p2) comprised in the polyurethane or polyisocyanurate of the material provided in step a).

[0147] 30. The process according to embodiment 28 or 29, wherein hydrolysis is carried out with a molar based ratio water (nwater) to the sum of urethane groups und urea groups (nu) in the polyurethane or to the sum of urethane groups and urea groups and the threefold amount of isocyanurate groups (nu) in the polyisocyanurate in the range of from 1 :1 to 1000:1, more preferably in the range of from 1.5:1 to 100:1, more preferably in the range of from 2:1 to 50:1.

[0148] 31 . The process according to any one of embodiments 28 to 30, wherein hydrolysis is carried out continuously, discontinuously (batch wise) or semi-batch-wise. 240243W001

[0149] - 20 -

[0150] 32. The process according to any one of embodiments 28 to 31 , wherein hydrolysis is carried out in the presence of an alcohol compound (hydroalkoholysis), preferably selected from the group consisting of monovalent alcohol, polyvalent alcohol and mixture thereof, more preferably a glycol selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, oligomer thereof, polymer thereof and mixtures of two or more thereof (hydroglycolysis).

[0151] 33. The process according to any one of embodiments 28 to 31 , wherein hydrolysis is carried out in the presence of an amine compound, preferably selected from the group consisting of ammonia, aliphatic diamine, aromatic diamine (such as TDA or PMDA), polyamine alkanol amines and mixtures of two or more thereof (hydroaminolysis).

[0152] 34. The process according to embodiment 33, wherein hydrolysis is carried out in the presence of ammonia (NH3), wherein hydrolysis is preferably carried out with a molar based ratio ammonia (nm) to polyurethane or polyisocyanurate in the range of from 1 :1 to 1000: 1 , more preferably in the range of from 1.5:1 to 100:1 , more preferably in the range of from 2: 1 to 50: 1 .

[0153] 35. The process according to embodiment 33 or 34, wherein hydrolysis is carried out in the presence of a solvent, preferably an organic solvent, more preferably an aromatic organic solvent, more preferably toluene.

[0154] 36. The process according to any one of embodiments 33 to 35, wherein hydrolysis is carried out under autogenous pressure, preferably in a closed vessel, more preferably in an autoclave.

[0155] 37. The process according to any one of embodiments 33 to 36, wherein hydrolysis is carried out at a temperature of more than 150°C, preferably in the range of from 150 to 400°C, more preferably in the range of from 200 to 300°C.

[0156] 38. Polyol composition (PC) obtained or obtainable from the process of any one of embodiments 1 to 37, preferably obtained or obtainable from a glycolyis of any one of embodiments 1 to 37.

[0157] 39. The polyol composition (PC) according to embodiment 38 comprising at least one component having OH group(s).

[0158] 40. The polyol composition (PC) according to embodiment 38 or 39 comprising at least a part of the phosphine oxide based flame retardant of formula (I).

[0159] 41 . A polyol composition (PC) comprising at least one component having OH group(s) and / or, preferably and, at least a part of the phosphine oxide based flame retardant of formula (I). 240243W001

[0160] - 21 -

[0161] 42. The polyol composition according to any one of embodiments 38 to 40 or 41 , wherein the at least one component having OH group(s) comprises at least one structural carbamate element ■ ■ ■ ■ HN-C(=O)-O ' .

[0162] 43. The polyol composition according to embodiment 42, wherein the at least one structural carbamate element

[0163] ■ ■ ■ -HN-C(=O)-O- ■ ■ constitutes at least 0.1 weight-%, preferably at least 0.5 weight-%, more preferably at least 1.0 weight-%, more preferably at least 1 .5 weight-% of the polyol composition, based on the total weight of the polyol composition being 100 weight-%; and / or, preferably and, the at least one structural carbamate element ■ ■ ■ -HN-C(=O)-O- ■ ■ constitutes at most 24 weight-%, preferably at most 21 weight-%, more preferably at most 18 weight-%, more preferably at most 15 weight-%, more preferably at most 12 weight-% of the polyol composition (PC), based on the total weight of the polyol composition being 100 weight-%.

[0164] 44. Use of the polyol composition (PC) of any one of embodiments 38 to 43 for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane rigid foam or a polyisocyanurate rigid foam.

[0165] 45. Method for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane or polyisocyanurate rigid foam, the method comprising reacting the polyol composition (PC) of any one of embodiments 38 to 44 with an isocyanate composition and optionally with at least one further polyol.

[0166] 46. Method according to embodiment 45, wherein the isocyanate composition comprises at least one diisocyanate.

[0167] 47. Method according to embodiment 45 or 46, wherein the at least one further polyol is selected from the group of polyesterpolyol and polyetherpolyol.

[0168] The present invention is further illustrated by the following reference examples, comparative examples, and examples.

[0169] Examples

[0170] Reference Example 1 : Polyisocyanurate rigid foam preparation

[0171] A1-1 : Polyesterol based on aromatic dicarboxylic acids and diethylene glycol with an OH number of 240 mgKOH / g

[0172] A1-2: Polyetherol based on ethylene oxide with an OH number of 180 mgKOH / g

[0173] A2-1 : Polyether siloxane

[0174] A3-1 : Potassium formate solution (40 wt%) in monoethylene glycol (54 wt%) and water (6 wt%)

[0175] A3-2: Mixture of 19 wt% N, N, N’, N”, N’-pentamethyldiethylenetriamine in polypropylene glycol (M = 450 g / mol) 240243W001

[0176] - 22 -

[0177] A4-1 : Formic acid and water (mass ratio 85:15)

[0178] A4-2: n-Pentane and / so-pentane with a mass ratio of 80:20 flame retardants:

[0179] A5-1 : Tris-(2-chloroisopropyl) phosphate (TCPP)

[0180] A5-2: Triphenylphosphine oxide (TPPO) from Sigma Aldrich

[0181] A5-3: isobutyl di(hydroxypropyl)phosphine oxide (Amgard 1243)

[0182] B-1 : polymeric 4,4'-dipheny Imethane diisocyanate (MD I), average functionality in the range of from 2.8 to

[0183] 2.9 (Lupranat M 50)

[0184] Polyisocyanurate rigid foams (PIR foams) were prepared based on a composition as in Table 1.

[0185] Table 1

[0186] PIR foam recipe with varying phosphorus flame retardants acomparable examplebinventive example

[0187] Reference Example 2: Chemical recycling

[0188] A glycolysis was carried out in a temperature-controlled 2-liter glass reaction vessel with a thermostatic jacket equipped with a stirrer, reflux condenser and dosing funnel in a nitrogen atmosphere. The respective polyalcohol was heated to a temperature of 210 °C together with optionally a catalyst. Then the respective PIR foam in powder form was added in portions so that the reaction mixture could still be stirred. After adding the last portion, stirring continued until a clear reaction product was obtained. 240243W001

[0189] - 23 -

[0190] Reference Example 3: Needle height test

[0191] The post-expansion of a respective PIR foam was evaluated by the needle height test. Therefore, 80 g of a reaction mixture for the preparation of the respective PIR foam were mixed in a cardboard cup having a volume of 0.735 1. At the time of the gel time, a pin was pressed into the foam at the upper edge of the cup. After the rising process of the polyurethane foam mold had ended, the difference in length between cup edge and needle was read off with a ruler.

[0192] Reference Example 4: Compressive Strength 3D corrected

[0193] Nine specimens measuring 50 mm x 50 mm x 50 mm were taken to determine compressive strength according to DIN EN 844. The compression strength was measured against the foam rise direction (top) and perpendicular to the foam rise direction (X and Y direction, respectively). Each orientation was measured three times, the geometrical mean was calculated and corrected based on a density of 35 kg / m3.

[0194] Reference Example 5: Quantitative13C NMR

[0195] The content of urethane functional groups in the samples was determined by quantitative13C-NMR spectroscopy. All NMR spectra were recorded at T = 298.2 K on a Bruker Avance III 500 spectrometer operating at 500.13 MHz for1H and 125.77 MHz for13C. The spectrometer was equipped with a 10 mm z-gradient BBO room temperature probe (broadband observe probe optimized for heteronuclear detection). Chemical shifts are referenced to tetramethylsilane (TMS, <5(TMS) = 0 ppm).13C 1 D spectra were recorded under quantitative conditions using the zgig pulse program (inverse-gated proton decoupling) with a recording of 64k data points, the relaxation delay D1 was chosen as 10 seconds (which was sufficient due to the presence of a paramagnetic relaxation agent), and 2048 transients were summed up per spectrum. For processing in the Bruker TopSpin 4.0.9 software, 32k data points were used (no zero filling), an exponential window function with a line broadening of 1 .0 Hz was applied. Automatic baseline correction with a polynomial of 5 was performed, phase correction was performed manually by the user.

[0196] Samples were prepared by exact weighting (Mettler-Toledo XP205DR analytical balance) of the internal standard dimethyl terephthalate (DMT, Sigma-Aldrich Supelco, traceCert) and the analyte in a suitable vial, followed by dissolution in deuterated tetrahydrofuran (THF-ds) with traces of TMS as internal reference for the chemical shift and 10 mg / ml chromium(lll) acetylacetonate (CrHI(acac)3) as paramagnetic relaxation agent. The samples were transferred into 10 mm NMR tubes for measurement. Deuterated solvents and TMS were purchased from Euriso-Top GmbH.

[0197] The content of urethane functional groups was calculated by using the following equation: 240243W001

[0198] - 24 -

[0199] In this equation, w = mass fraction of the analyte in the sample [g / 100 g], = peak intensity of the analyte, / st = peak intensity of the standard, EP = sample mass [g], Est = mass of the standard [g], AK = protons / molecule of analyte, Ast = protons / molecule of the standard, MK = molecular weight of the analyte [g / mol], Mst = molecular weight of the standard [g / mol], and Rst = purity of the standard [g / 100 g].

[0200] For quantification, triplicate determinations were conducted. Evaluation was performed by using 2 carbon atoms / mol- ecule of the internal standard DMT (at approx. 165.5 ppm) and 1 carbon atom / urethane functional group of the analyte (at approx. 153.2 ppm). The validity of the assignment was furthermore confirmed by NMR structure elucidation using1H and13C 1 D NMR spectroscopy in combination with 2d correlation experiments (HSQC, HMBC).

[0201] In cases where the spectral region for DMT was occupied by signals arising from the sample, e.g. due to a content of terephthalic acid in the samples, other internal standards (preferably 1 ,3,5-trimethoxy benzene (CAS: 621-23-8) or tetrachloronitrobenzene (CAS: 117-18-0)) could be used.

[0202] Comparative Example 1 : Glycolysis (atempt) of PIR foam 1

[0203] The production of a recycled polyol A1-R1 was carried out as described above in Reference Example 1 . For this purpose, 750 g of diethylene glycol and 1.5 g of 1,4-diazabicyclo[2.2.2]octane were heated to 210 °C. After the addition of two portions of PIR foam 1 powder, which correspond to a total of 114 g of PIR foam 1 powder (this corresponds to a theoretical content of PIR foam 1 in the reaction mixture of 13% by mass), no complete degradation could be achieved and a further dosage of PIR powder was not possible to add due to the limited stirring ability of the reaction mixture. On the other hand, a heterogeneous reaction mixture with swollen PIR foam 1 particles was obtained, which were not further degraded. An increase in the reaction temperature from 210 °C to 235 °C did not lead to any change. The attempt was aborted unsuccessfully after 12 hours.

[0204] Comparative Example 2: Glycolysis of PIR foam 1

[0205] The production of a recycled polyol A1-R2 was carried out as described above in Reference Example 1 . For this purpose, 950 g of triethylene glycol and 25 g of potassium carbonate were heated to 210 °C. After the addition of six portions of PIR foam 1 powder, which correspond to a total of 1000 g of the PIR foam 1 powder, a complete degradation could be achieved. After a reaction time of 6 h, a clear polyol was obtained. However, NMR analysis (31P{1H}) confirmed that the flame retardant (TCPP) did not remain stable in the glycolysis reaction. The TCPP-specific31P signal was missing. In contrast, new signals around 0 ppm were measured which indicated the formation of acidic P- O groups.

[0206] Example 1 : Glycolysis of PIR foam 2 240243W001

[0207] - 25 -

[0208] The production of a recycled polyol A1-R3 was carried out as described above in Reference Example 1 . For this purpose, 763 g of triethylene glycol were heated to 210 °C. After the addition of six portions of PIR foam 2 powder, which correspond to a total of 800 g of the PIR foam 2 powder, a complete degradation could be achieved. After a reaction time of 6 h, a clear polyol was obtained. NMR analysis (31P{1H}) of the obtained polyol confirmed that the flame retardant (TPPO) remained stable through the glycolysis reaction and was recovered quantitatively by31P NMR. The calculated carbamate content of recycled polyol A1-R3 was 3.5 weight-%, determined based on quantitative13C NMR according to Reference Example 5.

[0209] Example 2: Glycolysis of PIR foam 3

[0210] The production of the recycled polyol A1-R4 was carried out as described above in Reference Example 1 . For this purpose, 763 g of triethylene glycol were heated to 210 °C. After the addition of six portions of PIR foam 3 powder, which correspond to a total of 800 g of the PIR foam 3 powder, a complete degradation could be achieved. After a reaction time of 6 h, a clear polyol was obtained. NMR analysis (31P{1H}) of the polyol confirmed that the flame retardant (Amgard 1243) remained stable through the glycolysis reaction. The calculated carbamate content of recycled polyol A1-R3 was 3.8 weight-%, determined based on quantitative13C NMR according to Reference Example 5.

[0211] The results of Comparative Example 1 and Examples 1 and 2 are summarized in Table 2 below:

[0212] Table 2

[0213] Glycolysis results of the PIR foams

[0214] Example 3: Hydroaminolysis of PIR foam 3

[0215] PIR foam 3 was milled and 5 g were filled into a 3.5 litre stirred pressure autoclave. About 50 g toluene, 50 g water and 15 g NH3 were added and the reactor was heated-up to 220°C and held at these conditions for 8 hours to allow hydroaminolysis of the foam. Afterward the reactor was cooled down to room temperature and was depressurized.

[0216] A two-phase reaction mixture was taken from the reactor and allowed to separate. About 45 g of a upper organic phase and 47 g of a lower aqueous phase was withdrawn. Elementary analysis of the aqueous phase showed a phosphor content of 0.089g P / 100g according to 0.17 g phosphine oxide based flame retardant. NMR analysis (31P{1H}) confirmed, that the flame retardant remained stable in the hydroaminolysis reaction. Elementary analysis of milled PIR foam 3 used in the reaction showed 3.66 weight-% phosphor according to 0.18 g flame retardant. So more 240243W001

[0217] - 26 - than 94 % of the flame retardant could be recovered via the aqueous phase. Another 1 .7% could be found in the organic phase. The other parts were probably mass losses during the lab procedure.

[0218] Example 4: Preparation of Polyisocyanurate rigid foams with recycled polyols

[0219] A1-2: Polyetherol based on ethylene oxide with an OH number of 180 mgKOH / g

[0220] A1-3: Polyesterol based on aromatic dicarboxylic acids and diethylene glycol with an OH number of 215 mgKOH / g

[0221] A1-R2: recovered polyol from Comparative Example 2 (phosphine oxide-free)

[0222] A1-R3: recovered polyol from Example 1 (containing phosphine oxide, TPPO)

[0223] A1-R4: recovered polyol from Example 2 (containing phosphine oxide, Amgard 1243)

[0224] A2-2: Polyether siloxane

[0225] A3-1 : Potassium formate solution (40 wt%) in monoethylene glycol (54 wt%) and water (6 wt%)

[0226] A3-3: Mixture of 16.8 wt% bis[2-(N,N-dimethylamino)ethyl] ether in polypropylene glycol (M = 450 g / mol)

[0227] A4-1 : Formic acid and water (mass ratio 85:15)

[0228] A4-2: n-Pentane and / so-pentane with a mass ratio of 80:20

[0229] A5-1 : Tris-(2-chloroisopropyl) phosphate

[0230] B-1 : polymeric 4,4'-dipheny Imethane diisocyanate (MDI), average functionality in the range of from 2.8 to

[0231] 2.9 (Lupranat M 50)

[0232] Polyisocyanurate rigid foams (PIR foams) were prepared based on a recipe as in Table 3. The properties were determined as indicated in Table 3.

[0233] Table 3

[0234] PIR foams recipe and properties with varying phosphorus flame retardants 240243W001

[0235] - 27 - acomparable examplebinventive example

[0236] * The "gel time" is measured by repeatedly inserting a metal rod into the foamed reaction mixture and abruptly detecting a significantly increased resistance of the reaction mixture, which indicates the end point of the gel time. ** determined according to Reference Example 3

[0237] *** determined according to Reference Example 4

[0238] **** determined according to DIN EN ISO 11925-2

[0239] "Gel time” indicates the transition of the reaction mixture from a liquid to a solid state. Gel time for PUR foams is de- termined / determinable according to ASTM D7487-18, while for PIR foams, as indicated above, gel time is measured by repeatedly inserting a metal rod into the foamed reaction mixture and abruptly detecting a significantly increased resistance of the reaction mixture, which indicates the end point of the gel time. 240243W001

[0240] - 28 -

[0241] Due to incomplete degradation of PIR foam 1 in the preparation of comparable example A1-R1, polyol A1-R1 was unsuited for the preparation of PU or PI rigid foam.

[0242] A comparison of PIR foam 4 with PIR foam 5 and PIR foam 6 showed improved material properties when using a phosphine oxide containing recycled polyol. PIR foam 5 and foam 6, respectively, had a decreased needle height with respect to PIR foam 4. Furthermore, a lower heat release rate was measured in the cone calorimetry test with PIR foam 5 and PIR foam 6 compared to PIR foam 4.

Claims

240243W001- 29 -Claims1 . A process for recycling of polyurethane or polyisocyanurate foam comprising a) Providing a polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) and which comprises a phosphine oxide based flame retardant of formula (I)wherein R1, R2and R3are independently of each other selected from the group consisting of branched and unbranched C1 to C10 alkyl group and C6 to C12 aryl group; b) Depolymerization of the polyurethane or polyisocyanurate of the material provided in step a), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I).

2. The process according to claim 1 , wherein the polyol composition (PC) obtained in step b) comprises at least 40 weight-%, preferably at least 50 weight-%, more preferably at least 60 weight-%, more preferably at least 65 weight-% of the phosphine oxide based flame retardant of formula (I), relative to the amount of the phosphine oxide based flame retardant of formula (I) in the polyurethane or polyisocyanurate material provided according to a) being 100 weight-%.

3. The process of claim 1 or 2, wherein R1, R2and R3are independently of each other a branched or unbranched C1 to C5 alkyl group, wherein the branched or unbranched C1 to 05 alkyl group independently for each of R1, R2, R3is unsubstituted or substituted, preferably unsubstituted or substituted with at least one hydroxyl group; and / or wherein R1, R2and R3are independently of each other a 06 aryl group, wherein each 06 aryl group is unsubstituted or substituted with at least one substituent selected from hydroxyl group, amino group, thio group and branched and unbranched 01 to 05 alkyl group, preferably each 06 aryl group is unsubstituted.

4. The process of any one of claims 1 to 3, wherein the phosphine oxide based flame retardant of formula (I) is selected from triphenylphosphine oxide (TPPO), isobutyl di(hydroxypropyl)phosphine oxide and mixtures of triphenylphosphine oxide and isobutyl di(hydroxypropyl)phosphine oxide.

5. The process of any one of claims 1 to 4, wherein the polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) provided in step a) comprises in the range of from 0.1 to 50 weight-%, preferably in the range of from 0.5 to 10 weight-% of phosphine oxide based flame retardant of formula (I), based on the total weight of the polyurethane or polyisocyanurate material being 100 weight-%.240243W001- 30 -6. The process of any one of claims 1 to 5, wherein the polyurethane or polyisocyanurate material which is obtained from at least one polyol (P1) provided in step a) comprises less than 1 weight-% of a phosphorous ester-based flame retardant, based on the total weight of the polyurethane or polyisocyanurate material being 100 weight-%; wherein the phosphorous ester-based flame retardant is preferably selected from the group consisting of tris(2-chloroethy I )phosphate, tri s(ch loroisopropy l)phosphate, tris(1 , 3-d ich loro-2-propy I) phosphate, tris(2-ethylhexyl)phosphate, tricresylphosphate, tris-(2,3-dibromo)phosphate, tetrakis-(2-chlorethyl)- ethylenediphosphate, dimethylphosphonate, dimethylpropylphosphonate, diphenylcresylphosphate, triethylphosphate, diethyl (hydroxymethyl)phosphonate, resorcinol bis(diphenyl phosphate), and mixtures of two or more thereof.

7. The process according to any one of claims 1 to 6, wherein the polyurethane or polyisocyanurate material is halogen-free.

8. The process according to any one of claims 1 to 7, wherein the depolymerization according to step b) is carried out by a method selected from the group consisting of glycolysis, hydrolysis, alcoholysis, aminolysis, and ammonolysis, preferably glycolysis or hydrolysis.

9. The process according to any one of claims 1 to 8, wherein step (b) comprises b.1 ) optionally size reduction of the polyurethane or polyisocyanurate material provided in step a), thereby obtaining a size reduced polyurethane or polyisocyanurate material; b.2) Depolymerization of the polyurethane or polyisocyanurate of the material provided in step a) or of the size reduced material obtained in b.1 ), which is obtained from at least one polyol (P1) and at least one isocyanate (11), thereby obtaining a polyol composition (PC) comprising at least one component having OH group(s), at least a part of the phosphine oxide based flame retardant of formula (I), and optionally at least one amine component or amine derivative from the isocyanate 11 .

10. The process according claim 8 or 9, wherein the depolymerization according to step b) or b.2) is carried out by glycolysis.11 . The process according to claim 8 or 9, wherein the depolymerization according to step b) or b.2) is carried out in the presence of water by hydrolysis, wherein hydrolysis preferably is a method selected from the group consisting of hydrolysis, hydroalcoholysis, hydroaminolysis, hydroammonolysis and mixtures of two or more thereof.

12. Polyol composition (PC) obtained or obtainable from a glycolysis of any one of claims 1 to 11 comprising at least one component having OH group(s) and at least a part of the phosphine oxide based flame retardant of formula (I), wherein the at least one component having OH group(s) comprises at least one structural carbamate element ■ ■ ■ ■ HN-C(=O)-O ' , wherein preferably the at least one structural carbamate element240243W001- 31 -■ ■ ■ ■ HN-C(=O)-O- ■ ■ constitutes at least 0.1 weight-%, preferably at least 0.5 weight-%, more preferably at least 1.0 weight-%, more preferably at least 1 .5 weight-% of the polyol composition, based on the total weight of the polyol composition being 100 weight-%; and / or, preferably and, the at least one structural carbamate element ■ ■ ■ -HN-C(=O)-O- ■ ■ constitutes at most 24 weight-%, preferably at most 21 weight-%, more preferably at most 18 weight-%, more preferably at most 15 weight-%, more preferably at most 12 weight-% of the polyol composition (PC), based on the total weight of the polyol composition being 100 weight-%.

13. Use of the polyol composition (PC) of claim 12 for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane rigid foam or a polyisocyanurate rigid foam.

14. Method for preparation of a polyurethane or polyisocyanurate material, preferably a polyurethane or polyisocyanurate rigid foam, the method comprising reacting the polyol composition (PC) of claim 12 with an isocyanate composition and optionally with at least one further polyol.

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