A new method for recycling polyisocyanurates.

Abstract

The present invention relates to a process for the depolymerization of polyisocyanurates, in particular flexible and rigid polyisocyanurate foams, by which the valuable raw material of polyisocyanurates can be recovered in high yield and in good quality, i.e. in a quality that allows the use of the recycled raw material for the production of new polyurethanes, preferably polyurethane foams, or polyisocyanurates, preferably polyisocyanurate foams.

Description

[Technical Field]

[0001] The present invention relates to a process for the depolymerization of polyisocyanurates, in particular rigid polyisocyanurate foams, by which the valuable raw material of polyisocyanurates can be recovered in high yield and good quality, i.e. in a quality that allows the use of the recycled raw material for the production of new chemicals, in particular new polyurethanes, preferably polyurethane foams or polyisocyanurates, preferably polyisocyanurate foams.

[0002] Polyurethanes are highly useful materials in the production of rigid and flexible foams, curable and microcellular elastomers, sealants, coatings, and adhesives. Their versatility, relatively low cost, and excellent properties have led to rapid growth of the polyurethane industry over the past 50 years. Currently, thousands of tons of polyurethane are produced annually worldwide, and various methods have been developed for chemical recycling of polyurethanes, including glycolysis, ammonolysis, aminolysis, acidolysis, and hydrolysis. These methods have in common that they cleave not only primarily urethane and urea groups, but also adjacent uretdione, carbodiimide, allophanate, and biuret groups.

[0003] Polyisocyanurate polymers differ from polyurethanes in that they contain isocyanurate groups, which, due to their ring structure, are more stable and less reactive than the functional groups that are cleaved during the chemical degradation of polyurethanes. Another difference between polyurethanes and polyisocyanurates is that polyurethanes are typically formed by the reaction of polyisocyanates with polyether polyols, whereas polyisocyanurates are obtained by the reaction of polyisocyanates with polyester polyols. In contrast to polyether groups, polyester groups are also cleaved during chemical degradation. Therefore, chemical methods developed and used for polyurethane recycling cannot be applied to polyisocyanurates.

[0004] Due to their higher chemical stability, polyisocyanurate foams are used as insulating boards in applications with particularly high demands on strength and flame retardancy. Those skilled in the art have long known that the high chemical stability of polyisocyanurates can be achieved by a large number of isocyanurate groups. The prevailing view in the art has been that in chemical recycling to recover raw materials for polyisocyanurate foams, especially in recycling processes based on hydrolysis, polyisocyanurate foams cannot be cut and the isocyanurate structure is largely preserved.

[0005] PNGribkova et al., "Degradation of a polyisocyanurate obtained by polycyclotrimerization of 4,4'-di-isocyanatodiphenylmethan," Polymer Science USSR, Vol. 22, pp. 299-304, compares the thermal decomposition, thermohydrolysis, and thermooxidative decomposition of isocyanurates. Under all conditions, homolytic decomposition and the formation of CO and H2 were observed, and it was found that high yields of raw materials could not be obtained. This confirms the prevailing view in the art that polyisocyanurates cannot be recycled into monomers that can be reused to produce new polyisocyanurates or polyurethanes.

[0006] As a result of the high chemical stability of polyisocyanurates, the development of chemical recycling methods to date has focused on polyurethane foams containing polyether polyols and having an isocyanate index of less than 150.

[0007] Resource scarcity, climate change, environmental impacts, and growing awareness of eco-friendly products are leading to an increased demand for new technologies to recycle plastics. This is especially true for polyurethanes, but also for polyisocyanurates, due to the large amounts present on the market.

[0008] There is therefore a strong need to provide an efficient and sustainable method for recycling polyisocyanurates in order to recover valuable raw materials in good yield and in good quality, i.e., preferably in a quality that allows their reuse as raw material for new polyurethanes and polyisocyanurates.

[0009] It was therefore an object of the present invention to provide a new process for the depolymerization of polyisocyanurates and a process for isolating and recovering the recycled hydrolysis product, preferably for reuse in producing chemicals. In particular, it is an object of the present invention to provide a new process for the depolymerization of polyisocyanurates, in which ring cleavage of the polyisocyanurates and urethane bond scission occurs.

[0010] A particular object of the present invention was to provide a process that can be carried out in standard equipment, i.e. a steel reactor.

[0011] Another particular problem of the present invention was to provide a process that can be carried out at lower temperatures and with good yields.

[0012] Another particular object of the present invention was to provide a method that allows for the easy separation of the hydrolysis reactants, including any phase transfer catalyst, from the recovered raw materials used to prepare the products of the hydrolysis, i.e., the isocyanurates. Separation should be possible under mild conditions.

[0013] Another particular object of the present invention was to provide a method with good yield and almost no side reactions. The method of the present invention should enable the cleavage of more than 85%, preferably more than 90%, particularly preferably more than 95%, and even more preferably 100% of the existing isocyanurate groups of the raw material. In this context, cleavage of isocyanurate groups means that the first bond of the isocyanurate group is cleaved and ring opening occurs.

[0014] The method of the present invention should be applicable to polyisocyanurates having a high isocyanate index of preferably 150 or more, preferably >150, more preferably >250.

[0015] A further specific problem to be solved by the present invention was to provide a method that allows for the recovery of polyols and / or amines and / or polyamines in a quality very close to that of the raw materials used to produce the polyisocyanurates that were subjected to hydrolysis. It should be possible to use a high proportion of the recovered polyols and / or amines and / or polyamines for the production of new chemicals, preferably isocyanates, polyurethanes, polyisocyanurates or polyureas, or for reuse in other applications, such as as epoxy curing agents or crosslinking agents for other polymers.

[0016] Further issues not explicitly mentioned above can be derived from the ensuing description, examples and the overall content of the claims.

[0017] The inventors have surprisingly discovered a method for hydrolyzing polyisocyanurates, which comprises the steps of: The polyisocyanurate is prepared by reacting one or more polyols selected from the group consisting of polyester polyols, mixtures of polyester polyols, and mixtures of polyester polyols and polyether polyols with an excess of one or more isocyanates selected from the group consisting of organic isocyanates, mixtures of organic isocyanates, organic polyisocyanates, mixtures of organic polyisocyanates, and mixtures of organic isocyanate(s) and organic polyisocyanate(s); and The hydrolysis is carried out by contacting the polyisocyanurate with water in the presence of a base, one or more carboxylic acids containing two or more carboxylic acid groups per molecule and corresponding to the carboxylic acid(s) used to prepare the polyester polyol(s) used to prepare the polyisocyanurate; one or more polyols corresponding to the polyol(s) used to prepare the polyester polyol(s) used to prepare the polyisocyanurate; one or more organic amines and / or polyamines corresponding to the organic isocyanates or polyisocyanates used to prepare the polyisocyanurates; Generate and The base is Contains alkali metal cations and / or ammonium cations and has a pK of 1 to 10 at 25°C b a base having a value of 0, preferably free of primary, secondary and / or tertiary amino groups; pK <1 at 25°C b and a strong inorganic base having a value wherein the method comprises: It has been found that this makes it possible to recover the raw materials for polyisocyanurates, i.e., carboxylic acid(s) and / or polyol(s) and / or organic amine(s) and / or organic polyamine(s), in high yield and purity.

[0018] The process of the present invention provides a particularly high cleavage rate of the existing isocyanurate groups, of more than 85%, preferably more than 90%, particularly preferably more than 95%, and even more preferably 100%, based on the initial amount of isocyanurate groups present in the raw material. The cleavage percentage is measured using TMS as a standard. 13 It can be determined by the disappearance of a signal at about 150 ppm in C NMR.

[0019] In addition to the ring cleavage of the existing isocyanurate groups, the method of the present invention also results in the cleavage of the polyester polyol used to prepare the polyisocyanurate into its raw materials, i.e., the corresponding carboxylic acid(s) and polyol(s) can be recovered. These reaction products can be easily separated from the resulting amine formed as a further reaction product. This will allow the recovery of recycled raw materials with high purity.

[0020] The recycled amine component of the isocyanurate, preferably the aromatic amine component, can be recovered in a purity that allows, for example, phosgenation to polyisocyanate. The polyol(s) and carboxylic acid(s) can also be obtained in a purity that allows reuse for the production of polyurethane or polyisocyanurate, or for use in other applications such as polyester. In particular, fine-celled, uniform, low-interference foams that meet all requirements, for example, in terms of density, strength, or drainage, can be produced. Advantageously, the recycled product of the present invention can be used to prepare new polyurethane or polyisocyanurate foams without adversely affecting the foam's properties.

[0021] This method is particularly beneficial because it allows for the recycling of polyester polyol-based polyisocyanurate foams having a high Isocyanate Index of 150 or greater, preferably >150, and more preferably >250, which was not previously possible.

[0022] A wide variety of inexpensive and / or less corrosive or non-corrosive bases can be used in the process of the present invention to effectively depolymerize polyisocyanurates, particularly bases containing alkali metal and / or ammonium cations with a pK of 1 to 10 at 25°C. bThe base having a value of 0.1 to 1.0, preferably free of primary, secondary and / or tertiary amino groups, is a weak inorganic base, preferably a weak non-corrosive inorganic base, which allows the process of the present invention to be carried out in standard equipment under less corrosive or non-corrosive conditions.

[0023] In a preferred embodiment, a phase transfer catalyst is added during hydrolysis, i.e., a base-catalyst combination is used. The use of such a base-catalyst combination improves the room temperature yield but increases the effort required to separate and purify the reaction product. This is because the phase transfer catalyst is an additional component that must be separated from the reaction product. The use of a phase transfer catalyst also incurs additional costs. Nevertheless, the improvement in room-time yield may more than compensate for the disadvantages of using a phase transfer catalyst. The method of the present invention is highly flexible, allowing those skilled in the art to optimize the method by using a base alone or a base-catalyst combination.

[0024] The method of the present invention therefore provides a method for hydrolyzing a polyisocyanurate, comprising the steps of: The polyisocyanurate is prepared by reacting one or more polyols selected from the group consisting of polyester polyols, mixtures of polyester polyols, and mixtures of polyester polyols and polyether polyols with an excess of one or more isocyanates selected from the group consisting of organic isocyanates, mixtures of organic isocyanates, organic polyisocyanates, mixtures of organic polyisocyanates, and mixtures of organic isocyanate(s) and organic polyisocyanate(s); The hydrolysis is carried out by contacting the polyisocyanurate with water in the presence of a base-catalyst combination comprising a base and a catalyst, the base-catalyst combination being selected from the group consisting of base-catalyst combination (I), (II), or (III), one or more carboxylic acids containing two or more carboxylic acid groups per molecule and corresponding to the carboxylic acid(s) used to prepare the polyester polyol(s) used to prepare the polyisocyanurate; one or more polyols corresponding to the polyol(s) used to prepare the polyester polyol(s) used to prepare the polyisocyanurate; one or more organic amines and / or polyamines corresponding to the organic isocyanates or polyisocyanates used to prepare the polyisocyanurates; Generate The base-catalyst combination (I) comprises a base containing an alkali metal cation and / or an ammonium cation and having a pKb value of 1 to 10 at 25°C, preferably free of primary, secondary and / or tertiary amino groups, and a catalyst selected from the group consisting of quaternary ammonium salts containing ammonium cations containing 6 to 30 carbon atoms and organic sulfonates containing at least 7 carbon atoms; and The base-catalyst combination (II) comprises a strong inorganic base having a pKb value of <1 at 25°C and, as a catalyst, a quaternary ammonium salt containing an ammonium cation containing 6 to 14 carbon atoms, preferably 6 to 12 carbon atoms, when the ammonium cation contains a benzyl residue; and The base-catalyst combination (III) comprises a strong inorganic base having a pKb value of <1 at 25°C and, as a catalyst, a quaternary ammonium salt containing an ammonium cation containing 15 to 30 carbon atoms, preferably 15 to 28, more preferably 15 to 24, even more preferably 16 to 22, and most preferably 16 to 20 carbon atoms; Preferably, the process comprises a method that allows the raw materials for the polyisocyanurate, i.e., the carboxylic acid(s) and / or polyol(s) and / or organic amine and / or organic polyamine, to be recovered in high yield and purity.

[0025] The present inventors have found that it is preferable to use ammonium cations as phase transfer catalysts. Ammonium cations with a low number of carbon atoms, i.e., less than 15, can be used as effectively as those with a higher number of carbon atoms, i.e., 15 to 30. The use of such phase transfer catalysts allows for increased yields and increased flexibility in terms of reaction temperature.

[0026] Without being bound by any theory, the inventors believe that the particular mild reaction conditions that can be applied in the processes of the present invention, particularly those involving the use of base-catalyst combinations (I), (II) and (III), avoid the formation of by-products that can cause problems during reuse of the recovered products.

[0027] Further advantages will become apparent from the ensuing description, examples, claims and drawings.

[0028] MODE FOR CARRYING OUT THE INVENTION Before describing the present invention in more detail, some important terms are defined below.

[0029] As used in this specification, examples, and claims, the verb "to comprise" and its conjugations are used in an open-ended sense to mean that the items following the word are included, but items not specifically mentioned are not excluded. In its preferred embodiment, "comprising" includes "consisting of," which means that the items following the word "comprising" are included without additional items not specifically mentioned.

[0030] A reference to an element with the indefinite article "a" or "an" does not exclude the possibility that more than one element is present, unless the context clearly requires that one and only one element is present. Thus, the indefinite article "a" or "an" normally means "one or more."

[0031] The terms "catalyst" and "activator" are used interchangeably in this invention.

[0032] In the context of the present invention, polyurethane (PU) is understood to mean a product obtainable by the reaction of a polyisocyanate and a polyol or a compound having an isocyanate-reactive group. Polyurethanes that can be used in the process of the present invention are polyurethanes prepared from polyethers and polyisocyanates containing active hydrogen. Polyurethanes of this type are well known and are described, for example, in Ulrich, "Urethane Polymers," in Encyclopedia of Chemical Technology, Vol. 23, pp. 576-608 (1983) and Backus et al., "Polyurethanes," in Encyclopedia of Polymer Science and Technology, Vol. 13, pp. 243-303 (1988). Any known polyurethane can be used in the process of the present invention; preferably, the polyurethane is polyurethane waste.

[0033] In the context of the present invention, polyisocyanurate (PIR) is understood to mean a product obtainable by reacting a polyol component with an excess of a polyisocyanate component, the polyol component comprising a polyester polyol or a mixture of polyester and polyether polyols. Preferably, the isocyanate index of the PIR is 150 or greater. During the reaction of the polyol component with the excess of the polyisocyanate component, urethane structures are formed as a result of the reaction of isocyanates with compounds of the polyol component that have reactive hydrogen atoms, and through the reaction of the isocyanate groups themselves, there is the formation of isocyanurate structures or further structures resulting from the reaction of isocyanate groups with other groups, such as polyurethane groups. Polyisocyanurates have likewise been known for a long time and are described in the prior art.

[0034] Isocyanate Index as used herein should be understood as the molar ratio of polyisocyanate component to polyol component multiplied by 100, or in other words, the molar ratio of isocyanate groups to isocyanate-reactive groups multiplied by 100.

[0035] Preferably, rigid PIR foams are used in the present invention. "Rigid foam" is a well-established technical term. The well-known and fundamental difference between flexible and rigid foams is that flexible foams exhibit elastic behavior and therefore deformation is reversible. Rigid foams, on the other hand, are permanently deformed. Further information on rigid foams can also be found in "Kunststoffhandbuch, Band 7, Polyurethane", Carl Hanser Verlag, 3rd edition 1993, chapter 6. The terms "Hartfoam" or "rigid foam" are treated synonymously within the meaning of the present invention.

[0036] The method of the present invention is preferably a method for hydrolyzing a polyisocyanurate, comprising the steps of: the polyisocyanurate is produced by reacting one or more polyols selected from the group consisting of polyester polyols, mixtures of polyester polyols, and mixtures of polyester polyols and polyether polyols with an excess of one or more isocyanates selected from the group consisting of organic isocyanates, mixtures of organic isocyanates, organic polyisocyanates, mixtures of organic polyisocyanates, and mixtures of organic isocyanate(s) and organic polyisocyanate(s); The hydrolysis is carried out by contacting the polyisocyanurate with water in the presence of a base or base-catalyst combination (I), (II), or (III), one or more carboxylic acids containing two or more carboxylic acid groups per molecule and corresponding to the carboxylic acid(s) used to prepare the polyester polyol(s) used to prepare the polyisocyanurate; one or more polyols corresponding to the polyol(s) used to prepare the polyester polyol(s) used to prepare the polyisocyanurate; one or more organic amines and / or polyamines corresponding to the organic isocyanates or polyisocyanates used to prepare the polyisocyanurates; The method is characterized by generating The base is a base containing an alkali metal cation and / or an ammonium cation and having a pKb value of 1 to 10 at 25°C, preferably free of primary, secondary and / or tertiary amino groups; Strong inorganic bases with pKb values ​​<1 at 25°C and one or more bases selected from the group consisting of: and The base-catalyst combination (I) contains an alkali metal cation and / or an ammonium cation and has a pK of 1 to 10 at 25°C. ba base having a value of 0.01 to 0.01, preferably free of primary, secondary and / or tertiary amino groups, and a catalyst selected from the group consisting of quaternary ammonium salts containing ammonium cations containing 6 to 30 carbon atoms and organic sulfonates containing at least 7 carbon atoms, and The base-catalyst combination (II) has a pK of <1 at 25°C. b and as a catalyst, a quaternary ammonium salt containing an ammonium cation containing 6 to 14 carbon atoms, preferably 6 to 12 carbon atoms, when the ammonium cation contains a benzyl residue, and The base-catalyst combination (III) has a pK of <1 at 25°C. b and a quaternary ammonium salt containing an ammonium cation containing 15 to 30 carbon atoms, preferably 15 to 28, more preferably 15 to 24, even more preferably 16 to 22, and most preferably 16 to 20 carbon atoms, as a catalyst.

[0037] Preferred PIR, more preferably PIR foam, even more preferably rigid PIR foam to be used in the method of the present invention is a) one or more polyols selected from the group consisting of a polyester polyol, a mixture of polyester polyols, and a mixture of polyester polyols and polyether polyols, the polyols containing isocyanate-reactive groups, preferably OH groups, selected from OH groups, SH groups, NH groups, NH groups, and mixtures thereof, b) an excess of one or more isocyanates selected from the group consisting of organic isocyanates, mixtures of organic isocyanates, organic polyisocyanates, mixtures of organic polyisocyanates, and mixtures of organic isocyanate(s) and organic polyisocyanate(s); c) a catalyst that catalyzes the reaction of isocyanate-reactive groups with isocyanate groups and / or with each other, provided that at least one trimerization catalyst is included; d) optionally, a foam stabilizer e) optionally a propellant f) optionally further additives It is prepared by reacting in the presence of

[0038] Preferably, at least one polyol component a) contains two or more isocyanate-reactive groups, preferably OH groups, selected from the group consisting of OH, SH, NH, NH2, and mixtures thereof. More preferably, the polyol or mixture of polyols used as component a) has, in total, an average of 1.8 to 8, preferably 1.9 to 5, more preferably 2 to 3, and most preferably 2, said isocyanate-reactive groups, and an average of 2 to 12, preferably 2 to 10, more preferably 2 to 6 carbon atoms. A functionality that is not an integer, such as 1.8, can result from the fact that at least one polyol having a higher functionality, such as 2 or more, is mixed with at least one polyol having a functionality of 1, for example.

[0039] The polyol(s) may contain ether and / or carbonate functionality, preferably polyether polyols or polyether carbonate polyols.

[0040] Preferred polyester polyols are based on esters of polybasic aliphatic or aromatic carboxylic acids or mixtures of aromatic and aliphatic carboxylic acids, in which carboxylic acid(s) having 2 to 12, preferably 4 to 10, and more preferably 6 to 10 carbon atoms are used as component a) with 2 or 3, more preferably 2, carboxylic acid groups per molecule. Preferred aliphatic carboxylic acids are succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, and fumaric acid. Preferred aromatic carboxylic acids are phthalic acid, preferably (ortho)phthalic acid, isophthalic acid, terephthalic acid, and the isomeric naphthalenedicarboxylic acids. Polyester polyols are obtained by condensation of these polybasic carboxylic acids with polyols, i.e., polyhydric alcohols, preferably diols or triols having 2 to 12, more preferably 2 to 6 carbon atoms. Diols based on glycols and / or glycol ethers having a molecular weight of less than 180 g / mol, preferably less than 140 g / mol, are particularly preferred, with monoethylene glycol and / or diethylene glycol being most preferred. Preferably, the polyester polyol used to prepare the PIR contains an excess of polyhydric alcohol so that the polyhydric alcohol can also be present in an unbound form in the polyol component. Particularly preferred polyester polyols contain a high content of aromatic monomers. PIR made from such polyester polyols exhibit very high flame retardancy.

[0041] In a preferred embodiment, at least 90% by weight, preferably at least 95% by weight, more preferably at least 98% by weight of the polyol component used to prepare the polyisocyanurate is a polyester polyol having a hydroxyl number, measured according to DIN 53240, of 100 to 450 mg KOH / g, preferably 120 to 400 mg KOH / g, more preferably 140 to 350 mg KOH / g.

[0042] In addition to polyester polyols, one or more polyols selected from the group consisting of polyether polyols, polyether polycarbonate polyols, natural oil-based polyols (NOP; as described in WO 2005 / 033167, U.S. Patent Application Publication Nos. 2006 / 0293400, 2006 / 094227, 2004 / 096882, U.S. Patent Application Publication Nos. 2002 / 0103091, 2006 / 116456, and EP 1678232), filled polyols, and prepolymer-based polyols can be used in step a).

[0043] As the isocyanate b), any isocyanate or polyisocyanate containing at least two isocyanate groups can be used. Suitable isocyanates and polyisocyanates for the present invention are all organic isocyanates having two or more isocyanate groups. In general, aliphatic, cycloaliphatic, arylaliphatic, and mixtures thereof having two or more, preferably 2 to 4, isocyanate groups can be used. Such aromatic polyfunctional isocyanates are known per se. Preferably, alkylene diisocyanates having 4 to 12 carbon atoms in the alkylene group, such as dodecane 1,12-diisocyanate, 2-ethyltetramethylene 1,4-diisocyanate, 2-methylpentamethylene 1,5-diisocyanate, tetramethylene 1,4-diisocyanate, pentamethylene diisocyanate (PDI) and preferably hexamethylene 1,6-diisocyanate (HMDI), cyclohexane 1,3- and 1,4-diisocyanate and any mixtures of these isomers, 4,4'-methylenedicyclohexyl diisocyanate (H12MDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), Cycloaliphatic diisocyanates, such as toluene 2,4- and 2,6-diisocyanate (IPDI for short), hexahydrotolylene 2,4- and 2,6-diisocyanate and the corresponding isomer mixtures, and preferably aromatic diisocyanates and polyisocyanates, such as toluene 2,4- and 2,6-diisocyanate (TDI) and the corresponding isomer mixtures, naphthalene diisocyanate, diethyltoluene diisocyanate, mixtures of diphenylmethane 4,4', 2,4'- and 2,2'-diisocyanate (MDI), and polyphenylpolymethylene polyisocyanate (PMDI, also known as polymeric and crude MDI) and their higher condensed analogues with an average functionality of 2 to 4, are used. A further example is a mixture of crude MDI with toluene diisocyanate (TDI). The organic diisocyanates and polyisocyanates can be used individually or in the form of their mixtures.It is also possible to use the corresponding "oligomers" of diisocyanates (IPDI trimers based on isocyanurates, biurets, and uretdione). Furthermore, prepolymers based on the above isocyanates can be used. It is also possible to use isocyanates modified by incorporating urethane, uretdione, isocyanurate, allophanate, and other groups, so-called modified isocyanates. Examples of particularly suitable isocyanates are listed, for example, in EP 1712578, EP 1161474, WO 00 / 58383, U.S. Patent Application Publication No. 2007 / 0072951, EP 1678232, and WO 2005 / 085310, which are incorporated by reference in their entirety.

[0044] Most preferred are the organic polyisocyanate isomers of toluene diisocyanate (toluene 2,4- and 2,6-diisocyanate (TDI) in pure form or as isomeric mixtures of varying composition), diphenylmethane 4,4'-diisocyanate (MDI), "crude MDI" or "polymeric MDI" (which includes the 4,4' isomer of MDI, but also the 2,4' and 2,2' isomers and products with three or more rings), and the two-ring products referred to as "pure MDI", which consist primarily of a mixture of the 2,4' and 4,4' isomers, and prepolymers derived therefrom. Examples of particularly suitable isocyanates are detailed, for example, in EP 1712578, EP 1161474, WO 00 / 58383, U.S. Patent Application Publication No. 2007 / 0072951, EP 1678232 and WO 2005 / 085310, which are hereby incorporated by reference in their entirety.

[0045] As catalyst(s) c), any compound capable of accelerating the reaction of isocyanates with OH, NH or other isocyanate-reactive groups and with isocyanates themselves can be used. Here, conventional catalysts known in the art can be preferably used, including, for example, amines (cyclic, acyclic; monoamines, diamines, oligomers with one or more amino groups), ammonium compounds, organometallic compounds and metal salts, preferably salts of potassium, tin, iron, zinc or bismuth. It is also preferred to use a mixture of two or more of these catalysts.

[0046] Foam stabilizers (d) and their use in the production of PIR foams are known to those skilled in the art. As foam stabilizers, particularly surface-active compounds (surfactants) can be used. Although the use of foam stabilizers is optional, foam stabilizers are preferably used in the production of PIR foams. Foam stabilizers can be used to optimize the desired cell structure and foaming process. These compounds are well known in the art. Siloxanes are described, for example, in the following patent specifications, but their use is only described in classic PU foams (e.g., as molded foams, mattresses, insulating materials, building foams, etc.): CN 103665385, CN 103657518, CN 103055759, CN 103044687, US Patent Application Publication No. 2008 / 0125503, US Patent Application Publication No. 2015 / 0057384, EP 1520870, EP 1211279, EP 0867464, EP 0867465, EP 0275563. In addition to surface-active Si-containing compounds, Si-free surfactants can also be used. For example, EP 2295485 describes the use of lecithin, and US Patent 3746663 describes the use of vinylpyrrolidone-based structures as foam stabilizers, but only for the production of PU rigid foams. Further Si-free foam stabilizers are described, for example, in EP 2511328, DE 1020011007479, DE 3724716, EP 0734404, EP 1985642, DE 2244350 and US Patent 5236961.

[0047] The use of blowing agents to produce PIR foams is also well known in the art. It is possible to work with chemical and physical blowing agents. The choice of blowing agent strongly depends on the nature of the system. Depending on the amount of blowing agent used, foams with higher or lower densities are produced. Thus, a density of 5 kg / m is often used. 3 ~900kg / m 3 , preferably 5 to 350, more preferably 8 to 200 kg / m3 , especially 8 to 150 kg / m 3 Foams having densities of 0.1 to 1.0 can be prepared.

[0048] The preferred physical blowing agent used can be the corresponding compound with a suitable boiling point.Examples of blowing agents include liquefied CO2, nitrogen, air, volatile liquids, such as hydrocarbons with 3, 4 or 5 carbon atoms, preferably cyclo-, iso- and n-pentane, hydrofluorocarbons, preferably HFC245fa, HFC134a and HFC365mfc, hydrochlorofluorocarbons, preferably HCFC141b, hydrofluoroolefins (HFOs) or hydrohaloolefins, such as 1234ze, 1234yf, 1233zd(E) or 1336mzz, methyl formate, ketones, preferably acetone, ethers, preferably oxygen-containing compounds such as dimethoxymethane, or chlorinated hydrocarbons, preferably dichloromethane and 1,2-dichloroethane.

[0049] Likewise, it is possible to use chemical blowing agents, such as water or formic acid, which react with the NCO groups to liberate a gas, such as water or formic acid. As chemical blowing agents, one or more compounds can be used which react with the NCO groups by releasing a gas, such as water or formic acid, or which release a gas upon increasing the temperature during the reaction, such as sodium bicarbonate.

[0050] Optional additives f) which may be contained in the PIR include all substances known from the prior art and used in the production of polyisocyanurates, in particular polyisocyanurate foams, such as crosslinkers and chain extenders, stabilizers against oxidative degradation (known as antioxidants), flame retardants, surfactants, biocides, cell-refining additives, cell openers, solid fillers, antistatic additives, nucleating agents, thickeners, dyes, pigments, color pastes, fragrances and emulsifiers.

[0051] The process for producing rigid PIR foams can be carried out by known methods, for example by hand mixing, or preferably by means of a foaming machine. When the process is carried out by using a foaming machine, it is possible to use high-pressure or low-pressure machines.

[0052] Preferably, the polyisocyanurates used in the process of the present invention have an isocyanate index of 150 or greater, preferably >180, more preferably >250, and most preferably >250-500. Such polyisocyanates are particularly stable and have very high chemical and / or flame resistance. Therefore, such polyisocyanurates exhibit the highest market potential for the PIR recycling process of the present invention.

[0053] In a first particularly preferred embodiment of the present invention, the hydrolysis is carried out by contacting the PIR with water in the presence of a base, without the use of a phase transfer catalyst.

[0054] Preferably, the base used in this first particular preferred embodiment is containing alkali metal cations and / or ammonium cations, and having a pK at 25°C of 1 to 10, preferably 1 to 8, more preferably 1 to 7, and most preferably 1.5 to 6 b a base having a value of 0, 1 or 2, preferably free of primary, secondary and / or tertiary amino groups, and pK <1 at 25°C b Strong inorganic bases with values and more preferably, the nucleic acid comprises one or more bases selected from the group consisting of:

[0055] Contains alkali metal and / or ammonium cations with a pK of 1 to 10 at 25°C bMore preferred bases having a value are weak bases, low or non-corrosive bases. Also preferably, the base does not contain primary, secondary, and / or tertiary amino groups. Particularly preferably, the base used in the first particularly preferred embodiment is selected from the group consisting of alkali metal phosphates, alkali metal hydrogen phosphates, alkali metal carbonates, alkali metal silicates, alkali metal hydrogen carbonates, alkali metal acetates, alkali metal sulfites, ammonium hydroxide, and mixtures thereof. Even more preferably, the base is selected from the group consisting of alkali metal phosphates, alkali metal carbonates, alkali metal silicates, ammonium hydroxide, and mixtures thereof. Most preferably, the base is selected from the group consisting of alkali metal carbonates, alkali metal silicates, and mixtures thereof.

[0056] In a first particular preferred embodiment, the ammonium cation in the base used is NH4 + , NHR3 + , NH2R2 + , NH3R + For example, ammonium hydroxide includes NH4OH, NHR3OH, NH2R2OH, and NHROH, where R represents an organic residue, and the residues R in the ammonium cation can be the same or different. Preferably, the ammonium cation of the base is NH4 + Particularly preferably, the base does not contain alkaline earth metal cations due to the limited solubility of such bases in water.

[0057] Preferred alkali metals are selected from the group consisting of Na, K and Li and mixtures thereof, most preferably Na and K and mixtures thereof.

[0058] Preferably, the weak base is used in this first particularly preferred embodiment in the form of a base solution comprising a base and water, even more preferably as a saturated base solution. When a saturated base solution is used, the weight ratio of the saturated base solution to the polyisocyanurate, calculated at 25°C, is preferably in the range of 0.5 to 25, more preferably 0.5 to 15, even more preferably 1 to 10, and most preferably 2 to 7.

[0059] The aforementioned bases, i.e., containing alkali metal cations and / or ammonium cations, have a pK of 1 to 10 at 25°C. b The use of a base having a value of 0.1 to 100% and preferably free of primary, secondary and / or tertiary amino groups makes it possible to carry out the process of the present invention in standard equipment, preferably in steel reactors, without special corrosion protection, thus contributing significantly to reducing the investment costs of the plant.It is also possible to use very inexpensive bases, which contributes to reducing operating costs.

[0060] When strong inorganic base(s) are used, a pK at 25°C of <1, more preferably 0.5 to -4, even more preferably 0.25 to -3.5, and most preferably 0 to -2.9 b Preferably, the strong inorganic base(s) have a value of 0. It is further preferred that the strong inorganic base does not contain a C-H bond and / or a primary, secondary and / or tertiary amino group.

[0061] Particularly preferably, the strong inorganic base is selected from the group consisting of alkali metal hydroxides, alkali metal oxides, alkaline earth metal hydroxides, alkaline earth metal oxides, and mixtures thereof. Preferred alkali metals are selected from the group consisting of Na, K, and Li, and mixtures thereof, most preferably Na and K, and mixtures thereof. Preferred alkaline earth metals are selected from the group consisting of Be, Mg, Ca, Sr, Ba, and mixtures thereof, most preferably Mg and Ca, and mixtures thereof.

[0062] The use of a strong inorganic base as described above allows the process of the present invention to be carried out at lower temperatures and with very high yields, thus contributing significantly to reduced operating costs.

[0063] The strong inorganic base is preferably used in the form of a base solution containing the strong inorganic base and water. For efficient conversion, the concentration of the base in the base solution is particularly preferably 5 weight percent or more, preferably 5 to 70 weight percent, more preferably 5 to 60 weight percent, even more preferably 10 to 50 weight percent, particularly preferably 15 to 40 weight percent, and most preferably 20 to 40 weight percent, based on the weight of the base solution.

[0064] The amount of base in the reaction mixture should be sufficient to catalyze the desired hydrolysis of PIR at a practical rate. Preferably, the weight ratio of base to PIR is 0.01 to 25, more preferably 0.1 to 15, even more preferably 0.2 to 10, and most preferably 0.5 to 5.

[0065] In a second particularly preferred embodiment, the hydrolysis is carried out by contacting the PIR with water in the presence of a base-catalyst combination (I), the base comprising an alkali metal cation and / or an ammonium cation and having a pK of 1 to 10 at 25°C. b value, and the catalyst is selected from the group consisting of quaternary ammonium salts containing an ammonium cation containing 6 to 30 carbon atoms and organic sulfonates containing at least 7 carbon atoms.

[0066] In this second particularly preferred embodiment, the base used contains an alkali metal cation and / or an ammonium cation and has a pK of 1 to 10, preferably 1 to 8, more preferably 1 to 7, and most preferably 1.5 to 6 at 25°C. bThe base has a value of 0.05 to 0.05%. Preferably, a low or non-corrosive base is used. Also preferably, the base does not contain primary, secondary, and / or tertiary amino groups. Particularly preferably, the base is selected from the group consisting of alkali metal phosphates, alkali metal hydrogen phosphates, alkali metal carbonates, alkali metal silicates, alkali metal hydrogen carbonates, alkali metal acetates, alkali metal sulfites, ammonium hydroxide, and mixtures thereof. Even more preferably, the base is selected from the group consisting of alkali metal phosphates, alkali metal carbonates, alkali metal silicates, ammonium hydroxide, and mixtures thereof. Most preferably, the base is selected from the group consisting of alkali metal carbonates, alkali metal silicates, and mixtures thereof.

[0067] The ammonium cation in the base used in this second particularly preferred embodiment of the invention is NH + , NHR3 + , NH2R2 + , NH3R + For example, ammonium hydroxide includes NH4OH, NHR3OH, NH2R2OH, and NHROH, where R represents an organic residue, and the residues R in the ammonium cation can be the same or different. Preferably, the ammonium cation of the base is NH4 + Particularly preferably, the base of the present invention does not contain alkaline earth metal cations due to the limited solubility of such bases in water.

[0068] Preferred alkali metals are selected from the group consisting of Na, K and Li and mixtures thereof, most preferably Na and K and mixtures thereof.

[0069] The use of the aforementioned bases makes it possible to carry out the process of the present invention in standard equipment, preferably in steel reactors, without special corrosion protection, thus contributing significantly to reducing the investment costs of the plant. It is also possible to use very cheap bases, which contributes to reducing operating costs.

[0070] The amount of base in the reaction mixture of this second particularly preferred embodiment should be sufficient to catalyze the desired hydrolysis of PIR at a practically acceptable rate. Preferably, the weight ratio of base to PIR is in the range of 0.01 to 50, more preferably 0.1 to 25, and most preferably 0.5 to 20. Preferably, the base is used in the form of a base solution containing base and water, and even more preferably as a saturated base solution. When a saturated base solution is used, the weight ratio of the saturated base solution to polyisocyanurate, calculated at 25°C, is preferably in the range of 0.5 to 25, more preferably 0.5 to 15, even more preferably 1 to 10, and most preferably 2 to 7.

[0071] In a third particularly preferred embodiment, the hydrolysis is carried out by contacting the PIR with water in the presence of a base-catalyst combination (II), the base having a pK of <1 at 25°C. b The catalyst is a strong inorganic base having a value of 0.05 to 1.0, and the catalyst is a quaternary ammonium salt containing an ammonium cation containing 6 to 14 carbon atoms, preferably 6 to 12 carbon atoms, when the ammonium cation contains a benzyl residue.

[0072] The strong inorganic bases used in this third particularly preferred embodiment preferably have a pK at 25°C of less than 1, preferably between 0.5 and -4, more preferably between 0.25 and -3.5, and most preferably between 0 and -2.9. b Preferred strong inorganic bases are those that do not contain C—H bonds and / or primary, secondary and / or tertiary amino groups.

[0073] Particularly preferably, the strong inorganic base used in this third particularly preferred embodiment is selected from the group consisting of alkali metal hydroxides, alkali metal oxides, alkaline earth metal hydroxides, alkaline earth metal oxides, and mixtures thereof. Preferred alkali metals are selected from the group consisting of Na, K, and Li, and mixtures thereof, most preferably Na and K, and mixtures thereof. Preferred alkaline earth metals are selected from the group consisting of Be, Mg, Ca, Sr, Ba, and mixtures thereof, most preferably Mg and Ca, and mixtures thereof. Most preferably, an alkali metal is used that is selected from the group consisting of potassium or sodium, and mixtures thereof.

[0074] The use of the aforementioned bases allows the process of the present invention to be carried out at lower temperatures and with much higher yields, thus contributing significantly to reduced operating costs.

[0075] The amount of base in the reaction mixture must be sufficient to catalyze the desired hydrolysis of PIR at a practical rate. Preferably, the weight ratio of base to PIR is 0.01 to 25, more preferably 0.1 to 15, even more preferably 0.2 to 10, and most preferably 0.5 to 5. The base is preferably used in the form of a base solution containing base and water. For efficient conversion, the concentration of base in the base solution is particularly preferably 5% by weight or more, preferably 5 to 70% by weight, more preferably 5 to 60% by weight, even more preferably 10 to 50% by weight, particularly preferably 15 to 40% by weight, and most preferably 20 to 40% by weight, based on the weight of the base solution.

[0076] In a fourth particularly preferred embodiment, the hydrolysis is carried out by contacting PIR with water in the presence of a base-catalyst combination (III), the base having a pK of <1 at 25°C. bThe catalyst is a strong inorganic base having a value of 0.05 to 1.0, and the catalyst is a quaternary ammonium salt containing an ammonium cation containing 15 to 30 carbon atoms, preferably 15 to 28, more preferably 15 to 24, even more preferably 16 to 22, and most preferably 16 to 20 carbon atoms.

[0077] The strong inorganic base in the base-catalyst combination (III) preferably has a pK at 25°C of less than 1, preferably 0.5 to -4, more preferably 0.25 to -3.5, and most preferably 0 to -2.9. b Preferred strong inorganic bases are those that do not contain C—H bonds and / or primary, secondary and / or tertiary amino groups.

[0078] More preferably, the strong inorganic base is selected from the group consisting of alkali metal hydroxides, alkali metal oxides, alkaline earth metal hydroxides, alkaline earth metal oxides, and mixtures thereof. Even more preferably, the alkali metal of the base is selected from the group consisting of Na, K, and Li, and mixtures thereof, most preferably Na and K, and mixtures thereof, and / or the alkaline earth metal is selected from the group consisting of Be, Mg, Ca, Sr, Ba, and mixtures thereof, preferably Mg and Ca, and mixtures thereof. Most preferably, an alkali metal selected from the group consisting of potassium or sodium, and mixtures thereof, is used.

[0079] The use of the aforementioned base in this fourth particularly preferred embodiment makes it possible to carry out the process of the invention at lower temperatures and with much higher yields, thus contributing significantly to reduced operating costs.

[0080] In this fourth particularly preferred embodiment, the amount of base in the reaction mixture must be sufficient to catalyze the desired hydrolysis of PIR at a practically acceptable rate. Preferably, the weight ratio of base to PIR is 0.01 to 25, more preferably 0.1 to 15, even more preferably 0.2 to 10, and most preferably 0.5 to 5. The base is preferably used in the form of a base solution containing base and water. For efficient conversion, the concentration of base in the base solution is particularly preferably 5 to 70 weight percent, more preferably 5 to 60 weight percent, even more preferably 10 to 50 weight percent, particularly preferably 15 to 40 weight percent, and most preferably 20 to 40 weight percent, based on the weight of the base solution.

[0081] Preferably, the base or base-catalyst combinations (I), (II), and (III) or the reaction mixture during hydrolysis do not contain nonionic organic amine bases. "Nonionic" means that the base is not in the form of a salt, i.e., does not contain anions or cations, before being added to the reaction mixture. "Organic amine bases" are compounds that contain nitrogen in addition to carbon and hydrogen and react with acids to form salt-like compounds. Preferably, "organic amine bases" contain one or more C-H bonds. Nonionic organic amine bases are obtained in the same phase as the amines obtained as reaction products during hydrolysis, which increases the effort required to separate the amines obtained as reaction products.

[0082] The quaternary ammonium salts used as phase transfer catalysts in the base-catalyst combinations (I), (II) and (III) preferably have the general structure R1R2R3R4NX, where R1, R2, R3 and R4 are the same or different and are hydrocarbyl groups selected from alkyl, aryl and arylalkyl, and X is selected from the group consisting of halides, preferably chloride and / or bromide, hydrogen sulfate, alkyl sulfates, preferably methyl sulfate and ethyl sulfate, carbonate, hydrogen carbonate, carboxylate, preferably acetate, or hydroxide.

[0083] In a first particularly preferred embodiment using the base-catalyst combination (I), R1, R2, R3 and R4 and X are defined as follows: - R1 and R2 are the same or different and are alkyl groups having 1 to 12, preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 6, particularly preferably 1 to 5, and most preferably 1 to 4 carbon atoms, which alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear, saturated alkyl groups; R3 is selected from the group consisting of alkyl groups having 1 to 12, preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 6, particularly preferably 1 to 5, and most preferably 1 to 4 carbon atoms, aryl groups having 6 to 14, preferably 6 to 12, and most preferably 6 to 10 carbon atoms, and aralkyl groups having 7 to 14, preferably 7 to 12, and most preferably 7 to 10 carbon atoms, wherein the alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear; R4 is selected from the group consisting of alkyl groups having 3 to 12, preferably 3 to 10, more preferably 3 to 7, and most preferably 4 to 6 carbon atoms, aryl groups having 6 to 14, preferably 6 to 12, and most preferably 6 to 10 carbon atoms, and aralkyl groups having 7 to 14, preferably 7 to 12, and most preferably 7 to 10 carbon atoms, wherein the alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear and saturated; X is selected from the group consisting of halides, preferably chloride and / or bromide, hydrogen sulfate, alkyl sulfate, preferably methyl sulfate and ethyl sulfate, carbonate, hydrogen carbonate, acetate or hydroxide.

[0084] Even more preferable R1 to R4 are the total number of carbon atoms in the quaternary ammonium cation is 6 to 14, preferably 7 to 14, and more preferably 8 to 13; or The total number of carbon atoms in the quaternary ammonium cation is 15 to 30, preferably 15 to 28, more preferably 15 to 24, even more preferably 16 to 22, and most preferably 16 to 20. are selected from the definitions given above.

[0085] In a second particularly preferred embodiment using the base-catalyst combination (II), R1, R2, R3 and R4 and X are defined as follows: R1 to R3 are the same or different and are alkyl groups having 1 to 6, preferably 1 to 5, more preferably 1 to 4, even more preferably 1 to 3, particularly preferably 1 or 2, and most preferably 1 carbon atom, which alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear, saturated alkyl groups; R4 is selected from the group consisting of alkyl groups having 3 to 11, preferably 3 to 10, more preferably 3 to 8, and most preferably 4 to 6 carbon atoms, aryl groups having 6 to 11, preferably 6 to 10, and most preferably 6 to 8 carbon atoms, and aralkyl groups having 7 to 11, preferably 7 to 10, and most preferably 7 to 9 carbon atoms, wherein the alkyl groups may be linear, branched, cyclic, saturated, or unsaturated, and are most preferably linear, saturated alkyl groups; X is selected from the group consisting of halides, preferably chloride and / or bromide, hydrogen sulfate, alkyl sulfate, preferably methyl sulfate and ethyl sulfate, carbonate, hydrogen carbonate, acetate or hydroxide.

[0086] Even more preferable R1 to R4 are When R4 is different from a benzyl residue, R1 to R4 are selected so that the total number of carbon atoms in the quaternary ammonium cation is 6 to 14, preferably 7 to 14, more preferably 8 to 13; or When R4 is a benzyl residue, R1 to R3 are selected so that the total number of carbon atoms in the quaternary ammonium cation is 6 to 12, preferably 7 to 12, more preferably 8 to 11. The above definitions are selected as follows:

[0087] In a third particularly preferred embodiment using the base-catalyst combination (III), R1, R2, R3 and R4 and X are defined as follows: - R1 and R2 are the same or different and are alkyl groups having 1 to 12, preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 6, particularly preferably 1 to 5, and most preferably 1 to 4 carbon atoms, which alkyl groups may be linear, branched, cyclic, saturated or unsaturated, most preferably linear, saturated alkyl groups; R3 is selected from the group consisting of alkyl groups having 1 to 12, preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 6, particularly preferably 1 to 5, and most preferably 1 to 4 carbon atoms, aryl groups having 6 to 14, preferably 6 to 12, and most preferably 6 to 10 carbon atoms, and aralkyl groups having 7 to 14, preferably 7 to 12, and most preferably 7 to 10 carbon atoms, wherein the alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear; R4 is selected from the group consisting of alkyl groups having 3 to 12, preferably 3 to 10, more preferably 3 to 7, and most preferably 4 to 6 carbon atoms, aryl groups having 6 to 14, preferably 6 to 12, and most preferably 6 to 10 carbon atoms, and aralkyl groups having 7 to 14, preferably 7 to 12, and most preferably 7 to 10 carbon atoms, wherein the alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear and saturated; X is selected from the group consisting of halides, preferably chloride and / or bromide, hydrogen sulfate, alkyl sulfate, preferably methyl sulfate and ethyl sulfate, carbonate, hydrogen carbonate, acetate or hydroxide.

[0088] Even more preferably, R1 to R4 are selected from the above definitions such that the total number of carbon atoms in the quaternary ammonium cation is 15 to 30, preferably 15 to 28, more preferably 15 to 24, even more preferably 16 to 22, and most preferably 16 to 20.

[0089] When quaternary ammonium salts are used as phase transfer catalysts, the addition of even trace amounts of these phase transfer catalysts accelerates the hydrolysis rate, but it is preferred to use at least 0.5 weight percent, more preferably 0.5 to 15 weight percent, even more preferably 1 to 10 weight percent, especially more preferably 1 to 8 weight percent, very preferably 1 to 7 weight percent, and most preferably 2 to 6 weight percent of phase transfer catalyst, based on the weight of the polyisocyanurate.

[0090] Water functions as a reactant in the hydrolysis reaction of the present invention, and therefore need not be present in stoichiometric excess relative to the isocyanurate functional groups in the polymer being hydrolyzed; it is generally desirable to utilize a substantial amount of water, as it can conveniently serve as a reaction medium and solvent or carrier for the strong base and activator. For these reasons, water is preferably present in condensed (liquid) form. Typically, the weight ratio of PIR to water is 3:1 to 1:15.

[0091] Preferably, the polyisocyanurate is reacted with water and a base, or with water, a base and a phase transfer catalyst, At a temperature of 90°C to 220°C, preferably 100°C to 210°C, more preferably 110°C to 200°C, and most preferably 120°C to 190°C and / or 30 minutes to 20 hours, preferably 30 minutes to 16 hours, more preferably 30 minutes to 14 hours, even more preferably 45 minutes to 10 hours, particularly preferably 60 minutes to 8 hours, and very preferably 60 minutes to 6 hours and / or The contact is carried out at 1 to 30 bara, preferably 2 to 20 bara, more preferably 3 to 15 bara.

[0092] These reaction conditions offer economic benefits in terms of energy consumption and space-time yield. If the temperature is too low, the conversion may be incomplete or the reaction time may be too long. If the reaction temperature is too high or the reaction time is extended outside the aforementioned range, increased formation of by-products is observed, increasing energy consumption to unacceptable levels. The formation of by-products may result in undesirable coloration of the recovered product, which creates the need for additional purification steps. It has been found that conducting the reaction under elevated pressure shortens the reaction time and allows operation at lower temperatures.

[0093] To facilitate handling of the PIR, preferably a PIR foam, it is desirable to chop, powder, pulverize, or otherwise comminute the PIR so that it is in the form of relatively small particles or granules. If the PIR is a foam, it can be partially or fully compressed before contacting with water and the organic amine base. If the PIR is in solid form, an initial powdering step is highly advantageous for maximizing the surface area available for reaction (thereby shortening the reaction time required to achieve the desired level of hydrolysis).

[0094] The process of the present invention results in the efficient hydrolytic cleavage of the isocyanurate linkages present in the PIR being treated. Under reaction conditions, the polyester polyol obtained after ring cleavage of the isocyanurate linkages is further hydrolyzed to give the associated carboxylic acid and polyol.

[0095] Therefore, in the method of the present invention, one or more carboxylic acids containing two or more carboxylic acid groups per molecule and corresponding to the carboxylic acid(s) used to prepare the polyester polyol(s) used to prepare the polyisocyanurate, and one or more polyols corresponding to the polyol(s) used to prepare the polyester polyol(s) used to prepare the polyisocyanurate, and one or more organic amines and / or polyamines corresponding to the organic isocyanates or polyisocyanates used to prepare the polyisocyanurates is obtained.

[0096] Preferably, the one or more carboxylic acids obtained after hydrolysis are selected from the group consisting of phthalic acid, preferably (ortho)phthalic acid, terephthalic acid, isophthalic acid and the isomeric naphthalenedicarboxylic acids, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid and mixtures thereof.

[0097] Also preferred polyol(s) obtained after hydrolysis are diols based on glycols and / or glycol ethers having a molecular weight of less than 180 g / mol, preferably less than 140 g / mol, particularly preferred are monoethylene glycol and / or diethylene glycol.

[0098] More preferably, the one or more organic amines and / or polyamines obtained after hydrolysis are dodecane 1,12-diamine, 2-ethyltetramethylene 1,4-diamine, 2-methylpentamethylene 1,5-diamine, tetramethylene 1,4-diamine, pentamethylene diamine (PDA) and preferably hexamethylene 1,6-diamine (HMDA), cyclohexane 1,3- and 1,4-diamine and any mixtures of these isomers, 4,4'-methylenedicyclohexyl diisocyanate (H12MDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl Cycloaliphatic diamines such as cyclohexane (isophorone diamine or IPDA for short), hexahydrotolylene 2,4- and 2,6-diamine and the corresponding isomeric mixtures, and preferably aromatic diamines and polyamines, such as toluene 2,4- and 2,6-diamine (TDA) and the corresponding isomeric mixtures, naphthalenediamine, diethyltoluenediamine, mixtures of diphenylmethane 4,4',2,4'- and 2,2'-diamine (MDA) and polyphenylpolymethylenepolyamines and their more highly condensed analogues with an average functionality of 2 to 4.

[0099] The hydrolysis reaction can be carried out as a batch, continuous, or semi-continuous process in any suitable vessel or other apparatus (e.g., a stirred tank reactor or a screw extruder). Agitation or stirring of the reaction components is generally preferred to ensure intimate contact, a rapid rate of hydrolysis, and adequate temperature control.

[0100] After completion of the hydrolysis step, the reaction products are preferably separated from each other and, optionally, subjected to a purification step. Preferred separation and purification methods are selected from the group consisting of filtration, membrane separation, phase separation, chromatographic methods, distillation, extraction, and combinations of the above methods. Preferably, the amine component obtained as the reaction product of the hydrolysis is separated from other components by distillation or extraction, more preferably by distillation.

[0101] The recovered products of the process of the present invention, particularly one or more carboxylic acids and / or polyols and / or organic amines and / or polyamines, can be reused for the production of new chemicals, preferably polyurethanes, preferably polyurethane foams, or polyisocyanurates, preferably polyisocyanurate foams. The inventors have found that the recovered products of the process of the present invention can be used to produce high-quality PIR polyurethane foams, even without or with only minor additions of virgin polyols. This is a significant achievement.

[0102] The recovered amines can be converted to organic polyisocyanates by conventional processes and similarly used as components of polyurethanes or PIRs.

[0103] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following examples, therefore, should be construed as merely illustrative, and not limitative of the claims or the remainder of the disclosure in any way whatsoever.

[0104] Example Preparation of recycled PIR foam The formulations listed in Table 1 were used to prepare the PIR foams used in the hydrolysis tests described in Examples 1, 2, and 4 below, respectively, and the formulation listed in Table 2 for Example 3. The PIR foams were prepared by manual mixing. To this end, the polyol, flame retardant, catalyst, water, foam stabilizer, and blowing agent were weighed into a beaker and mixed with a disk stirrer (6 cm diameter) at 1000 rpm for 30 seconds. The amount of blowing agent evaporated during the mixing operation was determined by reweighing and replenished. Subsequently, the isocyanate (MDI) was added, and the reaction mixture was stirred with the described stirrer at 3000 rpm for 5 seconds. In the case of pour-in-place foaming, foaming was performed in the beaker itself; otherwise, the mixture was transferred to a paper-lined box with a base area of ​​27 × 14 cm.

[0105] [Table 1] * Stepanpol® PS 3152 from Stepan, OH value 315 mg KOH / g ** POLYCAT® 5 (pentamethyldiethylenetriamine) from Evonik Operations GmbH *** KOSMOS® 70LO from Evonik Operations GmbH **** TEGOSTAB® B8411 from Evonik Operations GmbH ***** Fyrol® PCF from ICL Industrial Products ****** Polymeric MDI, 200mPa*s, 31.5% NCO, functionality 2.7.

[0106] [Table 2] * POLYCAT® 5 from Evonik Operations GmbH ** KOSMOS® 70LO from Evonik Operations GmbH *** TEGOSTAB® B8411 from Evonik Operations GmbH **** Polymeric MDI, 200mPa*s, 31.5% NCO, functionality 2.7.

[0107] Example 1 The PIR foam prepared as described above was ground. 200 g of the ground PIR foam was mixed with 2083 g of aqueous K2CO3 solution (w(K2CO3) = 40%) and 12.5 g of tetra-n-butylammonium hydrogen sulfate. The resulting suspension was transferred to a 5 L pressure reactor. The mixture was heated to 170 °C and stirred for 5 hours. A pressure of approximately 7 bar was created. 2096 g of a two-phase product was obtained. The mixture was completely liquid, with no solid components visible.

[0108] The upper phase (130 g) is brown and, according to H-NMR studies, consists of 75-80% MDA.

[0109] C-NMR shows that only traces of urethane, urea and isocyanurate groups are present and that the conversion is >98%.

[0110] Example 2 The PIR foam prepared as described above was milled. 70 g of the milled PIR foam was combined with 700 g of aqueous NaOH (w(NaOH)=20%) and 7 g of tetra-n-butylammonium hydrogen sulfate. The resulting suspension was transferred to a 2 L pressure reactor equipped with a PTFE inliner. The mixture was heated to 150°C and stirred for 14 hours. A two-phase product was obtained. The upper oil layer (38 g) was separated. The mixture was completely liquid, with no solid components visible.

[0111] The oil phase is brown in color and, according to H-NMR studies, consists of 75–80% MDA.

[0112] C-NMR shows that only traces of urethane, urea and isocyanurate groups are present and that the conversion is >98%.

[0113] Example 3 The PIR foam prepared as described above was milled. 70 g of the milled PIR foam was combined with 700 g of aqueous NaOH (w(NaOH)=20%) and 7 g of tetra-n-butylammonium hydrogen sulfate. The resulting suspension was transferred to a 2 L pressure reactor equipped with a PTFE inliner. The mixture was heated to 150°C and stirred for 14 hours. A two-phase product was obtained. The upper oil layer (38 g) was separated. The mixture was completely liquid, with no solid components visible.

[0114] The oil phase is brown in color and, according to H-NMR studies, consists of 75–80% MDA.

[0115] C-NMR shows that only traces of urethane, urea and isocyanurate groups are present and that the conversion is >98%.

[0116] Example 4 The PIR foam prepared as described above was milled. 200 g of the milled PIR foam was mixed with 2080 g of an aqueous K2CO3 solution (w(K2CO3) = 40%). The resulting suspension was transferred to a 5 L pressure reactor. The mixture was heated to 170 °C and stirred for 5 hours. A pressure of approximately 7 bar was created. 2080 g of a two-phase product was obtained. The mixture was completely liquid, with no solid components visible.

[0117] The upper phase (130 g) is brown and consists of >80% MDA according to H-NMR studies.

[0118] C-NMR shows that only traces of urethane, urea and isocyanurate groups are present and that the conversion is >97%.

[0119] Example 4 shows that the process of the present invention can also be carried out in good yield without a phase transfer catalyst.

Claims

1. 1. A method for hydrolyzing a polyisocyanurate, comprising: preparing the polyisocyanurate by reacting one or more polyols selected from the group consisting of polyester polyols, mixtures of polyester polyols, and mixtures of polyester polyols and polyether polyols with an excess of one or more isocyanates selected from the group consisting of organic isocyanates, mixtures of organic isocyanates, organic polyisocyanates, mixtures of organic polyisocyanates, and mixtures of organic isocyanates and organic polyisocyanates; and the hydrolysis is carried out by contacting the polyisocyanurate with water in the presence of a base, thereby producing one or more carboxylic acids containing two or more carboxylic acid groups per molecule and corresponding to the carboxylic acids used to prepare the polyester polyol used to prepare the polyisocyanurate; one or more polyols corresponding to the polyols used to prepare the polyester polyols used to prepare the polyisocyanurates; one or more organic amines and / or polyamines corresponding to the organic isocyanates or polyisocyanates used to prepare the polyisocyanurates; The method is characterized by obtaining The base is containing alkali metal cations and / or ammonium cations and having a pK of 1 to 10 at 25°C ｂ a base having a value of 0, preferably free of primary, secondary and / or tertiary amino groups; pK<1 at 25°C ｂ and a strong inorganic base having a value The method of claim 1, further comprising one or more bases selected from the group consisting of:

2. the hydrolysis is carried out by contacting the polyisocyanurate with water in the presence of a base-catalyst combination comprising the base and a catalyst; the base-catalyst combination is selected from the group consisting of base-catalyst combinations (I), (II) or (III); and The base-catalyst combination (I) contains an alkali metal cation and / or an ammonium cation and has a pK of 1 to 10 at 25°C. ｂ a base having a value of 0.1 to 1.0, preferably free of primary, secondary and / or tertiary amino groups, and a catalyst selected from the group consisting of quaternary ammonium salts containing ammonium cations containing 6 to 30 carbon atoms and organic sulfonates containing at least 7 carbon atoms, and The base-catalyst combination (II) has a pK of <1 at 25°C. ｂ and as a catalyst, a quaternary ammonium salt containing an ammonium cation containing 6 to 14 carbon atoms, preferably 6 to 12 carbon atoms, when the ammonium cation contains a benzyl residue, and The base-catalyst combination (III) has a pK of <1 at 25°C. ｂ and as a catalyst, a quaternary ammonium salt containing an ammonium cation containing 15 to 30 carbon atoms, preferably 15 to 28, more preferably 15 to 24, even more preferably 16 to 22, and most preferably 16 to 20 carbon atoms, The method of claim 1.

3. pK of 1-10 at 25°C ｂ 3. The method of claim 1 or 2, characterized in that the base containing an alkali metal cation, which comprises and has a value, is selected from the group consisting of alkali metal phosphates, alkali metal hydrogen phosphates, alkali metal carbonates, alkali metal silicates, alkali metal hydrogen carbonates, alkali metal acetates, alkali metal sulfites, ammonium hydroxide and mixtures thereof.

4. 4. The method of claim 3, wherein the alkali metal is selected from the group consisting of Na, K and Li and mixtures thereof, most preferably Na and K and mixtures thereof.

5. 3. The process of claim 1 or 2, characterized in that the strong inorganic base is selected from the group consisting of alkali metal hydroxides, alkali metal oxides, alkaline earth metal hydroxides, alkaline earth metal oxides and mixtures thereof.

6. 6. The method of claim 5, wherein the alkali metals are selected from the group consisting of Na, K and Li and mixtures thereof, most preferably Na and K and mixtures thereof, and / or the alkaline earth metals are selected from the group consisting of Be, Mg, Ca, Sr, Ba and mixtures thereof, preferably Mg and Ca and mixtures thereof.

7. The phase transfer catalyst has the general structure R １ R ２ R ３ R ４ NX, wherein R １ , R ２ , R ３ and R ４ The process according to any one of claims 2 to 6, wherein X is the same or different and is a hydrocarbyl group selected from alkyl, aryl and arylalkyl, and X is selected from the group consisting of halide, preferably chloride and / or bromide, hydrogen sulfate, alkyl sulfate, preferably methyl sulfate and ethyl sulfate, carbonate, hydrogen carbonate, carboxylate, preferably acetate, or hydroxide.

8. For base-catalyst combinations (I) and (III), the catalyst has the general structure R １ R ２ R ３ R ４ NX, -R １ and R ２ are the same or different and are alkyl groups having 1 to 12, preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 6, particularly preferably 1 to 5, and most preferably 1 to 4 carbon atoms, which alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear, saturated alkyl groups; -R ３ is selected from the group consisting of alkyl groups having 1 to 12, preferably 1 to 10, more preferably 1 to 7, even more preferably 1 to 6, particularly preferably 1 to 5, and most preferably 1 to 4 carbon atoms, aryl groups having 6 to 14, preferably 6 to 12, and most preferably 6 to 10 carbon atoms, and aralkyl groups having 7 to 14, preferably 7 to 12, and most preferably 7 to 10 carbon atoms, said alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear; -R ４ is selected from the group consisting of alkyl groups having 3 to 12, preferably 3 to 10, more preferably 3 to 7, and most preferably 4 to 6 carbon atoms, aryl groups having 6 to 14, preferably 6 to 12, and most preferably 6 to 10 carbon atoms, and aralkyl groups having 7 to 14, preferably 7 to 12, and most preferably 7 to 10 carbon atoms, said alkyl groups may be linear, branched, cyclic, saturated or unsaturated, and are most preferably linear and saturated; X is selected from the group consisting of halides, preferably chloride and / or bromide, hydrogen sulfate, alkyl sulfate, preferably methyl sulfate and ethyl sulfate, carbonate, hydrogen carbonate, acetate or hydroxide, and / or For base-catalyst combination (II), the catalyst has the general structure R １ R ２ R ３ R ４ NX, -R １ ~R ３ are the same or different and are alkyl groups having 1 to 6, preferably 1 to 5, more preferably 1 to 4, even more preferably 1 to 3, particularly preferably 1 or 2, and most preferably 1 carbon atom, said alkyl groups may be linear, branched, cyclic, saturated or unsaturated, most preferably linear, saturated alkyl groups; -R ４ is selected from the group consisting of alkyl groups having 3 to 11, preferably 3 to 10, more preferably 3 to 8, and most preferably 4 to 6 carbon atoms, aryl groups having 6 to 11, preferably 6 to 10, and most preferably 6 to 8 carbon atoms, and aralkyl groups having 7 to 11, preferably 7 to 10, and most preferably 7 to 9 carbon atoms, said alkyl groups may be linear, branched, cyclic, saturated, or unsaturated, and are most preferably linear, saturated alkyl groups; 8. The process according to claim 7, wherein X is selected from the group consisting of halides, preferably chloride and / or bromide, hydrogen sulfate, alkyl sulfate, preferably methyl sulfate and ethyl sulfate, carbonate, hydrogen carbonate, acetate or hydroxide.

9. For the base-catalyst combination (I): R １ ~R ４ is selected so that the total number of carbon atoms in said quaternary ammonium cation is 6 to 14, preferably 7 to 14, more preferably 8 to 13; or R １ ~R ４ is selected so that the total of carbon atoms in said quaternary ammonium cation is from 15 to 30, preferably from 15 to 28, more preferably from 15 to 24, even more preferably from 16 to 22, and most preferably from 16 to 20.

10. For the base-catalyst combination (II): R ４ is different from a benzyl residue, and R １ ~R ４ is selected so that the total number of carbon atoms in said quaternary ammonium cation is 6 to 14, preferably 7 to 14, more preferably 8 to 13; or R ４ is a benzyl residue, and R １ ~R ３ is selected so that the total number of carbon atoms in said quaternary ammonium cation is 6 to 12, preferably 7 to 12, more preferably 8 to 11.

11. 11. The method according to any one of claims 2 to 10, wherein at least 0.5 weight percent, more preferably 0.5 to 15 weight percent, even more preferably 1 to 10 weight percent, especially more preferably 1 to 8 weight percent, very preferably 1 to 7 weight percent, and most preferably 2 to 6 weight percent of said quaternary ammonium salt is used as phase transfer catalyst, based on the weight of the polyisocyanurate.

12. The hydrolysis At a temperature of 90°C to 220°C, preferably 100°C to 210°C, more preferably 110°C to 200°C, most preferably 120°C to 190°C and / or 30 minutes to 20 hours, preferably 30 minutes to 16 hours, more preferably 30 minutes to 14 hours, even more preferably 45 minutes to 10 hours, particularly preferably 60 minutes to 8 hours, and most preferably 60 minutes to 6 hours and / or At atmospheric pressure or under elevated pressure, in particular at a pressure of 1 to 30 bara, preferably 2 to 20 bara, more preferably 3 to 15 bara The method according to any one of claims 1 to 11, wherein

13. The polyisocyanurate is a) OH group, SH group, NH group, NH ２ a polyester polyol or a mixture of polyester polyols or a mixture of polyester polyols and polyether polyols, containing isocyanate-reactive groups, preferably OH groups, selected from groups and mixtures thereof, b) an excess of one or more isocyanates selected from the group consisting of organic isocyanates, mixtures of organic isocyanates, organic polyisocyanates, mixtures of organic polyisocyanates, and mixtures of organic isocyanate(s) and organic polyisocyanate(s); c) a catalyst that catalyzes the reaction of said isocyanate-reactive groups with said isocyanate groups and / or with each other, provided that at least one trimerization catalyst is included. d) optionally, a foam stabilizer e) optionally, a propellant f) Optionally, further additives The method according to any one of claims 1 to 12, characterized in that the compound is produced by reacting in the presence of

14. The polyester polyol is one or more aromatic or aliphatic carboxylic acids or mixtures of aromatic and aliphatic carboxylic acids, said carboxylic acids having 2 or 3, more preferably 2, carboxylic acid groups and having from 2 to 12, preferably from 4 to 10, more preferably from 6 to 10 carbon atoms per molecule, A polyol or a mixture of polyols, at least one of which contains OH, SH, NH, NH groups. ２ 14. The method according to any one of claims 1 to 13, characterized in that the polyol or mixture of polyols has two or more isocyanate-reactive groups, preferably OH groups, selected from the group consisting of groups and mixtures thereof, and the polyol or mixture of polyols has in total an average of 1.8 to 8, preferably 1.9 to 5, more preferably 2 to 3 and most preferably 2, said isocyanate-reactive groups, and the polyol(s) has an average of 2 to 12, preferably 2 to 10, more preferably 2 to 6 carbon atoms, and the polyol(s) may comprise ether and / or carbonate functional groups, preferably polyether polyols or polyether carbonate polyols.

15. The aromatic carboxylic acid is selected from the group consisting of phthalic acid, preferably (ortho)-phthalic acid, isophthalic acid, terephthalic acid and the isomeric naphthalenedicarboxylic acids. and / or The aliphatic carboxylic acid is selected from the group consisting of succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, and fumaric acid.

15. The method of claim 14.

16. at least 90% by weight, preferably at least 95% by weight, more preferably at least 98% by weight of the polyol component used to prepare the polyisocyanurate is a polyester polyol having a hydroxyl number of 100 to 450 mg KOH / g, preferably 120 to 400 mg KOH / g, more preferably 140 to 350 mg KOH / g; and / or the organic isocyanate and / or polyisocyanate(s) is / are selected from the group consisting of monomeric, oligomeric or polymeric, aliphatic, cycloaliphatic, arylaliphatic or aromatic isocyanates having two or more, preferably two to four, isocyanate groups and mixtures thereof; and / or the polyisocyanurate has an isocyanate index of 150 or greater, preferably >180, more preferably >250, and most preferably >250 to 500; and / or The polyisocyanurate is foamed, preferably a rigid foam. The method according to claims 1 to 15, characterized in that

17. the one or more carboxylic acids obtained after the hydrolysis are selected from the group consisting of phthalic acid, preferably (ortho)-phthalic acid, terephthalic acid, isophthalic acid and the isomeric naphthalenedicarboxylic acids, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid and mixtures thereof, and / or the one or more polyols obtained after the hydrolysis are diols based on glycols and / or glycol ethers, particularly preferably monoethylene glycol and / or diethylene glycol, having a molecular weight of less than 180 g / mol, preferably less than 140 g / mol; and / or The one or more organic amines and / or polyamines obtained after the hydrolysis are selected from the group consisting of dodecane 1,12-diamine, 2-ethyltetramethylene 1,4-diamine, 2-methylpentamethylene 1,5-diamine, tetramethylene 1,4-diamine, pentamethylene diamine (PDA) and preferably hexamethylene 1,6-diamine (HMDA), cyclohexane 1,3- and 1,4-diamine and any mixtures of their isomers, 4,4'-methylenedicyclohexyl diisocyanate (H12MDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl silane (MDI), methyl ... cycloaliphatic diamines such as cyclohexane (isophoronediamine or IPDA for short), hexahydrotolylene 2,4- and 2,6-diamine and the corresponding isomeric mixtures, and preferably aromatic diamines and polyamines, for example toluene 2,4- and 2,6-diamine (TDA) and the corresponding isomeric mixtures, naphthalenediamine, diethyltoluenediamine, mixtures of diphenylmethane 4,4', 2,4'- and 2,2'-diamine (MDA) and polyphenylpolymethylenepolyamines and their more highly condensed analogues having an average functionality of 2 to 4. The method according to any one of claims 1 to 16, characterized in that

18. 18. The method according to any one of claims 1 to 17, comprising the additional step of separating and recovering and optionally purifying the reaction product of said hydrolysis, preferably said separation and purification method being selected from the group consisting of filtration, membrane separation, phase separation, chromatographic methods, distillation, extraction and combinations of said methods.

19. 19. The method according to any one of claims 1 to 18, wherein the hydrolysis results in a cleavage rate of existing isocyanurate groups of more than 85%, preferably more than 90%, particularly preferably more than 95%, even more preferably 100%.

20. 20. Use of one or more carboxylic acids and / or polyols and / or organic amines and / or polyamines obtainable by the process according to any one of claims 1 to 19 for the production of new chemical substances, preferably polyurethanes, preferably polyurethane foams, or polyisocyanurates, preferably polyisocyanurate foams.

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