Base-induced chemical recycling of epoxy resins

Abstract

Provided herein are methods for the disassembly of epoxy-based polymers (EBPs) or fiber-reinforced EBPs (FREBPs). The methods may comprise any one or more of the following: (1) subjecting a raw material comprising one or more epoxy-based polymers to a particle size reduction step, thereby producing a particulate starting material; (2) combining a particulate starting material comprising an epoxy -based polymer with a solvent component and a base component to produce a reaction mixture; (3) removing the solvent from the reaction mixture to produce a solid reaction mixture; (4) conducting a solid-phase reaction within the solid reaction mixture, thereby producing a product mixture; and (5) recovering one or more desirable chemical products from the product mixture.

Description

BASE-INDUCED CHEMICAL RECYCLING OF EPOXY RESINSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 717,319, filed on November 7, 2024, the entire disclosure of which is hereby incorporated by reference in its entirety.FIELD

[0002] The present disclosure generally relates to methods for chemical recycling of epoxy resins. For example, provided herein are methods wherein a starting material comprising an epoxy resin is contacted with a solvent and a base, and wherein one or more desirable chemical constituents of the starting material are recovered.BACKGROUND

[0003] Fiber-reinforced epoxy-based polymers are lightweight, highly durable composite materials commonly used in multiple industries, including in the construction of automobiles, boats, airliners and wind turbine blades. Unfortunately, until recently, few commercially viable methods for recycling epoxy -based polymers were known in the art. There is increasing global concern about the environmental impact of composite materials after their useful service life has ended, and increasing interest in solutions that would reduce or eliminate the need to send such components to landfills.

[0004] In 2021, the wind turbine producer Siemens Gamesa introduced turbine blades based on epoxy resin system that allows the separation of embedded fibers from the resins under acidic conditions. Unfortunately, the epoxy fraction recovered using this technology is suitable only for a limited range of uses, such as a filler material.

[0005] One recent approach to the disassembly of EBPs is described in WO 2023 / 152245 Al to Ahrens et al. (“Ahrens”), the entire disclosure of which is hereby incorporated herein by reference. The method disclosed by Ahrens comprises contacting an EBP with an organometallic catalyst in an organic solvent mixture, thereby allowing for recycling of one or more chemical constituents of the epoxy -based polymer.

[0006] Another approach to the disassembly of EBPs is described in WO 2024 / 074703A1 to Sun et al. (“Sun”), the entire disclosure of which is hereby incorporated herein by reference. The method disclosed by Sun comprises contacting an EBP with a solvent system comprising at least one aprotic apolar organic solvent and an oxygen-containing base,thereby allowing for recycling of one or more chemical constituents of the epoxy-based polymer.

[0007] There is a need in the art for additional methods for disassembly of EBPs, and in particular methods that enable recycling the constituents of EBPs that would otherwise largely be deposited in landfills. In particular, there is a need in the art for methods that are capable of recovering a variety of desirable chemical constituents from EBPs, and which require less initial capital costs, require less operating costs, provide an improved safety profile, and / or are capable of recovering certain chemical constituents in a higher yield than previously disclosed methods.SUMMARY

[0008] In one aspect, provided herein are methods for the disassembly of epoxy-based polymers (EBPs) or fiber-reinforced EBPs (FREBPs). The methods may comprise any one or more of the following: (1) subjecting a raw material comprising one or more epoxy-based polymers to a particle size reduction step, thereby producing a particulate starting material; (2) combining a particulate starting material comprising an epoxy-based polymer with a solvent component and a base component to produce a reaction mixture; (3) removing the solvent from the reaction mixture to produce a solid reaction mixture; (4) conducting a solid-phase reaction within the solid reaction mixture, thereby producing a product mixture; and (5) recovering one or more desirable chemical products from the product mixture

[0009] For example, provided herein is a method for deconstructing an epoxy -based polymer, the method comprising (1) combining a particulate starting material comprising an epoxy-based polymer with a solvent component and a base component to produce a homogenous reaction mixture; (2) removing at least about 50 % by weight of the solvent component from the reaction mixture, thereby producing a solid reaction mixture; and (3) conducting a solid-phase reaction within the solid reaction mixture, thereby producing a product mixture.

[0010] Other objects and features will be in part apparent and in part pointed out hereinafter.DETAILED DESCRIPTION

[0011] Provided herein are methods for the disassembly of epoxy-based polymers (EBPs) or fiber-reinforced EBPs (FREBPs). The methods may comprise any one or more of the following: (1) subjecting a raw material comprising one or more epoxy-based polymers toa particle size reduction step, thereby producing a particulate starting material; (2) combining a particulate starting material comprising an epoxy-based polymer with a solvent component and a base component to produce a reaction mixture; (3) removing the solvent from the reaction mixture to produce a solid reaction mixture; (4) conducting a solid-phase reaction within the solid reaction mixture, thereby producing a product mixture; and (5) recovering one or more desirable chemical products from the product mixture.

[0012] Without being bound to a particular theory, embodiments of the methods provided herein may provide one or more advantages as compared to methods of deconstructing EBPs previously known in the prior art. For example, embodiments of the methods provided herein may provide a relatively high yield of desirable chemical products such as bisphenol A (BP A).

[0013] While a catalyst may optionally be employed in the methods provided herein, it has been discovered that commercially useful yields may be achieved even in the absence of a catalyst, and in particular without the need for an expensive metal catalyst or transition metal catalyst. Accordingly, the methods may be performed in the absence of a catalyst, such as a metal catalyst.

[0014] Additionally, the methods provided herein may advantageously be carried out using common, inexpensive solvents that present a relatively low risk to health and safety. For example, the methods provided herein may utilize a solvent comprising a Ci-Ce aliphatic alcohol, such as ethanol.Definitions

[0015] As used herein, the term “polymer” refers to a chemical compound composed of multiple linked repeating units having similar or identical structures (e.g., monomers).

[0016] As used herein, the term “monomer” refers to a compound that can react with other identical compounds, or with structurally similar compounds falling within the same chemical genus, to form extended structures comprising a plurality of repeating units (e.g., polymers). The term “monomer” may also be used herein to refer to the chemical structure that represents a repeating unit of a polymer. For example, the methods provided herein utilize monomers that comprise organic compounds that have been functionalized with epoxides and are useful to form epoxy-based polymers.

[0017] As used herein, the term “epoxy resin” means a composition that possesses one or more vicinal epoxy groups per molecule (for example, at least one 1,2-epoxy group per molecule). Examples of suitable epoxy resins are discussed in further detail below.

[0018] As used herein, the term “epoxy-based polymer” or “EBP” refers to a polymer formed by the reaction of at least one class of monomers comprising an epoxide functional group (also referred to as an epoxy functional group). The monomers may react with themselves and / or with other co-reactants, optionally in the presence of a catalyst, to form the epoxy-based polymer. For example, an epoxy-based polymer may be prepared by reacting an epoxy resin with itself and / or with other co-reactants, optionally in the presence of a catalyst.

[0019] As used herein, the term “fiber reinforced epoxy-based polymer” or “FREBP” refers to a composite material comprising at least one epoxy-based polymer and at least one fibrous material. As a non-limiting example, fiber reinforced epoxy -based polymer may be a composite material comprising one or more fibrous materials, and optionally one or more other materials, embedded within an epoxy-based polymer matrix. FREBPs are commonly used in multiple industries, including in the construction of automobiles, boats, airliners and wind turbines, among others.

[0020] As used herein, the term “fibrous material” refers to any non-spherical material which may be cured together with an epoxy-based polymer to improve the structural and / or durable integrity of the composite material, compared to the cured polymer without the presence of the fibrous material. Non-limiting examples of fibrous materials within the meaning of the present disclosure include glass, cellulose, plastic, steel, metal, and carbon fibers.

[0021] As used herein, the term “crosslinker” (or equivalently, “cross-linker”) refers any class of compounds that can react to connect two or more polymer chains. The term “crosslinker” may also be used to refer to the chemical structures connecting two or more polymer chains within a polymer network. For example, crosslinkers as defined herein include molecules that may react with epoxide-functionalized bisphenol derivatives to form epoxy-based polymers.

[0022] As used herein, the term “disassembly” refers generally to a chemical process that converts a starting a material ABCD into a product mixture comprising at least one of its base constituents A, B, C, or D, thereby allowing the recovery of at least one of A, B, C, or D. For purposes of the present disclosure, the term “disassembly” may be used interchangeably with “deconstruction,” “deconvolution,” and “degradation.”Epoxy-Based Polymers

[0023] The method provided herein may utilize a raw material and / or particulate starting material comprising one or more epoxy-based polymers. In general, the epoxy-based polymer may be produced by the polymerization of any well-known epoxy resin. For example, the epoxy resin may comprise a saturated or unsaturated aliphatic, cycloaliphatic, aromatic or heterocyclic compound which possesses at least one 1,2-epoxy group. Such a compound can be substituted, if desired, with one or more non-interfering substituents, such as halogen atoms, hydroxy groups, ether radicals, lower alkyls and the like.

[0024] Epoxy Resins

[0025] Epoxy resins useful to produce epoxy-based polymers include monoepoxides, diepoxides, polyepoxides, and mixtures thereof. Illustrative compounds are described in the Handbook of Epoxy Resins by H. E. Lee and K. Neville published in 1967 by McGraw-Hill, New York; and in U.S. Pat. No. 4,066,628, both of which are incorporated herein by reference.

[0026] The epoxy resin may comprise a compound having two vicinal epoxy groups. For example, the epoxy resin may comprise a compound having the following formula:Formula I wherein n has an average value of generally 0 or more, preferably from 0 to about 100, and more preferably from about 0.1 to about 50.

[0027] Exemplary compounds that may be present in epoxy resins include the glycidyl polyethers of polyhydric phenols and polyhydric alcohols. Non-limiting examples of epoxy resins include the diglycidyl ethers of resorcinol, catechol, hydroquinone, bisphenol, bisphenol A, bisphenol AP ( 1,1 -bi s(4-hydroxylphenyl)-l -phenyl ethane), bisphenol F, bisphenol K, tetrabromobisphenol A, phenol-formaldehyde novolac resins, alkyl substituted phenolformaldehyde resins, phenol-hydroxybenzaldehyde resins, cresol-hydroxybenzaldehyde resins, dicyclopentadiene-phenol resins, dicyclopentadiene-substituted phenol resins tetramethylbiphenol, tetramethyl-tetrabromobiphenol, tetramethyltribromobiphenol, tetrachlorobisphenol A; and any combination thereof.

[0028] Examples of diepoxides include diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of 2,2-bis(3,5-dibromo-4-hydroxyphenyl) propane (generally referred to as tetrabromobisphenol A). Other diepoxides include the diglycidyl ethers of dihydric phenols, such as those described in U.S. Pat. Nos. 5,246,751; 5,115,075; 5,089,588; 4,480,082 and 4,438,254, all of which are incorporated herein by reference; or the diglycidyl esters of dicarboxylic acids such as those described in U.S. Pat. No. 5,171,820, incorporated herein by reference. Other suitable diepoxides include for example, aco- diglycidyloxyisopropylidene-bisphenol-based epoxy resins such as those commercially known as D.E.R.® 300 and 600 series epoxy resins, which are available products from Olin Corporation. Mixtures of any two or more diepoxides can also be used.

[0029] Epoxy resins may also be prepared either by reaction of diglycidyl ethers of dihydric phenols with dihydric phenols or by reaction of dihydric phenols with epichlorohydrin (also known as “taffy resins”).

[0030] Preferred epoxy resins include, for example, the diglycidyl ethers of bisphenol A; 4,4'-sulfonyldiphenol; 4,4-oxydiphenol; 4,4'-dihydroxybenzophenone; resorcinol; hydroquinone; 9,9'-bis(4-hydroxyphenyl)fluorene; 4,4'-dihydroxybiphenyl or 4,4'-dihydroxy- a-methylstilbene and the diglycidyl esters of the dicarboxylic acids mentioned previously.

[0031] Cycloaliphatic epoxides may also be used to prepare epoxy-based polymers. A cycloaliphatic epoxide consists of a saturated carbon ring having an epoxy oxygen bonded to two vicinal atoms in the carbon ring for example as illustrated by the following general formula:Formula II wherein R is a hydrocarbon group optionally comprising one or more heteroatoms (such as, without limitation thereto Cl, Br, and S), or an atom or group of atoms forming a stable bond with carbon (such as, without limitation thereto, Si, P and B) and wherein n is greater than or equal to 1.

[0032] The cycloaliphatic epoxide may be a monoepoxide, a diepoxide, a polyepoxide, or a mixture of those. For example, any of the cycloaliphatic epoxide described in U.S. Pat. No. 3,686,359, incorporated herein by reference, may be used to prepare an epoxy-based polymer. As an illustration, the cycloaliphatic epoxides that may be used in the presentinvention include, for example, (3,4-epoxycyclohexyl-methyl)-3,4-epoxy-cyclohexane carboxylate, bis-(3,4-epoxycyclohexyl) adipate, vinylcyclohexene monoxide and mixtures thereof.

[0033] Particularly common epoxy-based polymers are those obtained using a bisphenol diglydicyl ether as a starting material, for example bisphenol A diglycidyl ether.Formula HIEpoxy-based polymers obtained using bisphenol A diglycidyl ether as a starting material are referred to herein as “bisphenol A based polymers.” In such embodiments, the useful compounds recovered by the methods provided herein may include bisphenol A (BP A).

[0034] The epoxy-based polymer may comprise a chemical moiety having one of the following structures:Formula IV Formula IV-i wherein Xi is selected from the group consisting of H, R, and -C(=O)R, wherein R is selected from the group consisting of Ci-Ce alkyl, Ci-Ce heteroalkyl, Ci-Ce alkoxy, Ci-Ce allyl, Ci-Ce heteroallyl, C4-Cs cycloalkyl, C4-Cs heterocycloalkyl, C4-Cs aryl, and C4-Cs heteroaryl, each of which may be optionally independently substituted with one or more substituents selected from the group consisting of -OH, -NH2, -L, -CL3, and -OCH3, wherein L is a halogen; andX2 is selected from the group consisting of C4-Cs cycloalkyl, C4-Cs heterocycloalkyl, C4-Cs aryl, and C4-Cs heteroaryl, each of which may be optionally independently substituted with one or more substituents selected from the group consisting of -OH, -NH2, -Q, -CQ3, and - OCH3, wherein each Q is independently selected from the group consisting of hydrogen, halogen, methyl, phenyl, and benzyl.

[0035] Xi may be selected from the group consisting of hydrogen and Ci-Ce alkyl. For example, Xi may be selected from the group consisting of hydrogen and methyl. For example, Xi may be hydrogen.

[0036] X2 may be an optionally substituted C4-C8 aryl. For example, X2 may be an aromatic Ce aryl (e.g., phenyl), which may be optionally independently substituted with one or more substituents selected from the group consisting of -OH, -NH2, -Q, -CQ3, and -OCH3, wherein each Q is independently selected from the group consisting of hydrogen, halogen, methyl, phenyl, and benzyl. For example, X2 may be selected from the group consisting of phenyl, benzyl, tolyl, phenol, and phenoxy.

[0037] For example, the epoxy-based polymer may comprise a chemical moiety having the following structure:Formula IVa wherein Xi and X2 are selected as described above, and wherein n is an integer greater than 1. For example, n may be an integer of at least 2, at least 5, at least 10, at least 50, at least 100, at least 200, at least 500, at least 1,000, or at least 10,000. For example, n may be an integer between 1 and 1000, between 1 and 500, between 1 and 400, between 1 and 300, between 1 and 200, or between 1 and 100. As a further example, n may be an integer between 50 and 100, s between 100 and 200, between 200 and 300, between 300 and 500, between 500 and 700, or between 700 and 1000.

[0038] As a further example, the epoxy-based polymer may comprise a chemical moiety having one of the following structures:Formula V Formula V-i wherein Xi and X2 are selected as described above, and wherein X3 is selected from the group consisting of-CR2- -NZ-, -O-, and -S-, wherein R is selected from the group consisting of Ci-Ce alkyl, Ci-Ce heteroalkyl, Ci-Ce alkoxy, Ci-Ce allyl, Ci-Ce heteroallyl, C4-C8 cycloalkyl, C4-C8 heterocycloalkyl, C4-C8 aryl, and C4-C8 heteroaryl, each of whichmay be optionally independently substituted with one or more substituents selected from the group consisting of -OH, -NH2, -L, -CL3, and -OCH3, wherein L is a halogen, and wherein NZ represents an amine based crosslinker and / or hardener selected from the group consisting of poly amide resins, poly(oxypropylene)diamine, 3-aminomethyl-3,5,5- trimethylcyclohexylamine, triethylenetetramines, tetraethylene-pentamines, trimethylolpropane tris[poly(propylene glycol), amine terminated] ether (T-403), and mixtures thereof.

[0039] X3 may be selected from the group consisting of -O- and -NZ-. For example, X3 may be -O-. Alternatively, X3 may be selected from the group consisting of poly amide resins, poly(oxypropylene)diamine, 3-aminomethyl-3,5,5- trimethylcyclohexylamine, triethylenetetramines, tetraethylene-pentamines, trimethylolpropane tris[poly(propylene glycol), amine terminated] ether (T-403), and mixtures thereof.

[0040] For example, the epoxy-based polymer may comprise a chemical moiety having the following structure:Formula Va wherein Xi, X2, X3, and n are selected as described above. Preferably, Xi is hydrogen, X2 is an optionally substituted C4-Cs aryl, and X3 is selected from -O- and -NZ-, wherein NZ may be selected as described above.

[0041] As a further example, the epoxy-based polymer may comprise a chemical moiety having one of the following structures:Formula Vb Formula Vc wherein Xi, X2, X3, and n are selected as described above.

[0042] As a still further example, the epoxy-based polymer may comprise a chemical moiety having the following structure:Formula VI wherein Xi and n are selected as described above, and R is selected from the group of C4-Cs aryl and bisphenol, each of which may be optionally independently substituted with one or more substituents selected from the group consisting of -OH, -NH2, -L, -CL3, and -OCH3, wherein L is a halogen. For example, in Formula VI, R may be bisphenol or a derivative thereof having the following structure:Formula Vl-i wherein Ri, R2, R3, R4, Rs, and Re are each independently selected from the group consisting of-H, -F, -Cl, -Br, -OH, -CH3, -CF3, -OCF3, phenyl, pyridyl, -CN, -NO2, and Ci-C6alkyl, and wherein Ri and R2 may alternatively come together to form a cyclohexyl moiety optionally substituted with one or more substituents selected from the group consisting of - CH3 and -CF3, and wherein the broken bonds of Formula VI-I represent the positions of the phenolic oxygens of bisphenol. Preferably, each of Ri, R2, R3, R4, Rs, and Re of Formula Vl-i are independently selected from the group consisting of-H, -F, -Cl, -Br, -OH, -CH3, -CF3, and phenyl.

[0043] As a still further example, the epoxy-based polymer may comprise a chemical moiety having the following structure:Formula VII wherein the moiety of Formula VII optionally comprises from 1 to 4 of each of R3 and R4, and wherein Ri, R2, R3, and R4 are each individually selected from the group consisting of - H, Ci-Ce alkyl, Ci-Ce alkenyl, -CF3, -F, -Cl, -Br, -OH, -NO2, -NH2, and phenyl, or wherein Ri and R2 come together to form a Ce cycloalkyl, and wherein Rs is selected from the group consisting of O and -NZ-, wherein NZ is selected as described above. Optionally, Rs may be further connected to another bisphenol entity of another epoxy polymer chain, thereby resulting in extensive crosslinking.

[0044] As a still further example, the epoxy-based polymer may comprise a chemical moiety having the following structure.wherein Rs is selected from the group consisting of O and -NZ-, wherein NZ is selected as described above, and wherein each Ar is independently selected from the group consisting of C4-C10 aryl, each of which may be optionally independently substituted with one or more substituents selected from the group consisting of -OH, -NH2, -L, -CL3, and -OCH3, wherein L is a halogen. For example, each Ar may be independently selected from the group consisting of phenyl and napththyl. Each Ar may be optionally independently substituted or cross-linked in the polymer, such as representing yet another bisphenol or bisphenol diglycidyl ether derived moiety.

[0045] The epoxy-based polymer may comprise a monomer selected from the group consisting of bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC, bisphenol Z, and derivatives thereof.

[0046] For example, epoxy-based polymer may comprise a monomer selected from the group consisting of bisphenol A and derivatives thereof.

[0047] The epoxy-based polymer may be selected from the group consisting of bisphenol A based polymers, bisphenol AP based polymers, bisphenol AF based polymers, bisphenol B based polymers, bisphenol BP based polymers, bisphenol C based polymers, bisphenol C based polymers, bisphenol E based polymers, bisphenol F based polymers, bisphenol G based polymers, bisphenol M based polymers, bisphenol S based polymers, bisphenol P based polymers, bisphenol PH based polymers, bisphenol TMC based polymers, bisphenol Z based polymers, and mixtures thereof. In another embodiment, the epoxy-based polymer is a bisphenol A based polymer.

[0048] Crosslinkers

[0049] The epoxy-based polymer may comprise one or more crosslinkers. Suitable crosslinkers for epoxy resins (also referred to as hardeners) are generally known to those skilled in the art. Non-limiting examples of crosslinkers that may be present in the epoxy-based polymers include poly amide resins, poly(oxypropylene)diamine, 3-aminomethyl-3,5,5- trimethylcyclohexylamine, triethylenetetramines, tetraethylene-pentamines, trimethylolpropane tris[poly(propylene glycol), amine terminated] ether (T-403), and mixtures thereof.Solvent Component

[0050] The method provided herein may utilize a solvent component comprising at least one solvent. For example, the solvent component may comprise an organic solvent.

[0051] Preferably, the solvent component comprises a polar protic solvent. For example, the solvent component may comprise a protic solvent having a dielectric constant of at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, or at least about 20.

[0052] Preferably, the solvent component is miscible with water. For example, the solvent component may consist of one or more polar, protic solvents that are miscible with water.

[0053] The solvent component may comprise an organic alcohol. For example, the solvent component may comprise an aliphatic organic alcohol (e.g., an aliphatic Ci-Cs alcohol). Non-limiting examples of suitable alcohols include methanol, ethanol, n-propanol, isopropanol, butanol, hexanol, heptanol, and mixtures thereof. For example, the solventcomponent may comprise methanol. As a further example, the solvent component may comprise ethanol.

[0054] Non-limiting examples of suitable solvents include methanol, ethanol, propanol, butanol, hexanol, heptanol, ethylene glycol, propylene glycol, butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, Dowanol DB (diethylene glycol monobutyl ether), Dowanol DPM (dipropylene glycol methyl), Dowanol PM (propylene glycol methyl ether), and mixtures thereof.Base Component

[0055] The method provided herein may utilize a base component comprising at least one base that mediates the disassembly of an epoxy-based polymer present in the particulate starting material. Preferably, the base component comprises at least one base in the form of a particulate solid.

[0056] While the base component may generally comprise particles of any size, it has been observed that the use of smaller particles facilitates more homogeneous mixing of the base component and the starting material, and additionally facilitates a faster solid-phase reaction. The base component may, as a non-limiting example, comprise a solid particulate base having a particle size distribution characterized by D90 of from about 100 pm to about 10 mm. More typically, the solid particulate base has a particle size distribution characterized by a D90 of less than about 10 mm, less than about 5 mm, less than about 2 mm, or less than about 1 mm. The solid particulate base typically has a particle size distribution characterized by a D50 of less than about 5 mm, less than about 2 mm, or less than about 1 mm.

[0057] For example, the base component may comprise a solid particulate base having a particle size distribution characterized by a D90 of less than about 1000 pm, for example, less than about 900 pm, less than about 800 pm, less than about 700 pm, less than about 600 pm, less than about 500 pm, less than about 400 pm, less than about 300 pm, less than about 200 pm, or even less than about 100 pm. The solid particulate base typically has a particle size distribution characterized by a D90 of at least about 50 pm, for example, at least about 75 pm, at least about 100 pm, at least about 200 pm, at least about 250 pm, or at least about 500 pm. The solid particulate base may have a particle size distribution characterized by a D90 that falls within a range bounded by any two values listed above. For example, the solid particulate base may have a particle size distribution characterized by a D90 that falls within a range of from about 100 pm to about 1000 pm, or from about 200 pm to about 500 pm.

[0058] For example, the base component may comprise a solid particulate base having a particle size distribution characterized by a Dso of less than about 500 pm, for example, less than about 400 pm, less than about 300 pm, less than about 250 pm, less than about 225 pm, less than about 200 pm, less than about 175 pm, less than about 150 pm, less than about 125 pm, or even less than about 100 pm. The solid particulate base typically has a particle size distribution characterized by a Dso of at least about 25 pm, for example, at least about 50 pm, at least about 75 pm, at least about 100 pm, at least about 150 pm, or at least about 200 pm. The solid particulate base may have a particle size distribution characterized by a Dso that falls within a range bounded by any two values listed above. For example, the solid particulate base may have a particle size distribution characterized by a Dso that falls within a range of from about 50 pm to about 300 pm, from about 75 pm to about 200 pm, or from about 100 pm to about 175 pm.

[0059] The base component may comprise an oxygen-containing base. For example, the base component may comprise a hydroxide base. Non-limiting examples of hydroxide bases include NaOH, LiOH, KOH, CsOH, RbOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2. The base component may comprise an alkoxide base. Non-limiting examples of alkoxide bases include butoxide, tert-butoxide, methoxide, ethoxides, isopropoxide, and salts thereof.

[0060] The oxygen-containing base may be present in the form of a salt comprising a cation selected from the group consisting of alkali metals and alkaline earth metals. For example, the oxygen-containing base may be present in the form of a sodium salt or a potassium salt. Non-limiting examples of suitable bases include NaOH, KOH, NaOBu, and NaOtBu. For example, the oxygen-containing base may be selected from the group consisting of NaOH and KOH. As a specific example, the oxygen-containing base may be NaOH. Alternatively, the oxygen-containing base may be KOH.

[0061] The base component may comprise a nitrogen-containing base. For example, the base component may comprise an amide. Non-limiting examples of amide bases include lithium diisopropylamide (LDA), lithium diethylamide (LDEA), sodium amide, and lithium bis(trimethylsilyl)amide. Alternatively, the base component may comprise an amine. Nonlimiting examples of amine bases include triethylamine, trimethylamine, diethylamine, dimethylamine, isopropylamine, pyridine and ammonia.Raw Material

[0062] The method provided herein may utilize a raw material comprising one or more epoxy-based polymers (for example, one or more fiber reinforced epoxy-based polymers).

[0063] The raw material may comprise, for example, an epoxy-based material present in a wind energy product. For example, the raw material may comprise an epoxy -based material recovered from a wind energy product that has been discarded and / or reached the end of its useful life. Non-limiting examples of wind energy products that comprise epoxy-based materials that may be useful raw materials in the context of the present disclosure include wind turbine blades and wind turbine nacelles.

[0064] The raw material may comprise, for example, an epoxy-based material present in an automotive product. For example, the raw material may comprise an epoxy-based material recovered from an automotive product that has been discarded and / or reached the end of its useful life. Non-limiting examples of automotive products that comprise epoxy-based materials that may be useful raw materials in the context of the present disclosure include automotive car body components, structural or semi -structural automotive parts, aerodynamic parts, composite battery boxes, composite fuel / gas tank systems, composite pressure vessels, composite rims, high roofs, composite springs, composite trucks and parts of the same, and composite trailers and parts of the same.

[0065] The raw material may comprise, for example, an epoxy-based material present in an aerospace product. For example, the raw material may comprise an epoxy-based material recovered from an aerospace product that has been discarded and / or reached the end of its useful life. Non-limiting examples of aerospace products that comprise epoxy-based materials that may be useful raw materials in the context of the present disclosure that comprise epoxybased materials that may be useful raw materials in the context of the present disclosure include aircraft wings, aircraft fuselage components, horizontal / vertical tailplanes, flaps, interior parts, nacelles, composite fuel / gas tank systems, and composite pressure vessels

[0066] The raw material may comprise, for example, an epoxy-based material present in a sporting goods product. For example, the raw material may comprise an epoxy-based material recovered from a sporting goods product that has been discarded and / or reached the end of its useful life. Non-limiting examples of sporting goods products that comprise epoxybased materials that may be useful raw materials in the context of the present disclosure include fishing rods, bicycle frames, tennis rackets, golf clubs, surfboards, kiteboads, foilboards, sailboats, and leisure and professional boats.

[0067] The raw material may comprise, for example, an epoxy-based material present in a civil engineering or construction product. For example, the raw material may comprise an epoxy -based material recovered from a civil engineering or construction product that has been discarded and / or reached the end of its useful life. Non-limiting examples of civil engineering or construction products that comprise epoxy-based materials that may be useful raw materials in the context of the present disclosure include composite rebar, composite structural reinforcement members, composite architectural elements, composite panels, epoxy castings, epoxy floorings, and other decorative, structural, and architectural epoxy coatings.

[0068] The raw material may comprise, for example, an epoxy-based material present in an industrial or consumer electronics product. For example, the raw material may comprise an epoxy -based material recovered from an industrial or consumer electronics product that has been discarded and / or reached the end of its useful life. Non-limiting examples of industrial or consumer electronics products that comprise epoxy-based materials that may be useful raw materials in the context of the present disclosure include printed circuit boards, switches, housings, composite insulators, and electrical castings.The raw material may comprise, for example, an epoxy-based material present in a general industrial or infrastructure product. For example, the raw material may comprise an epoxybased material recovered from a general industrial or infrastructure product that has been discarded and / or reached the end of its useful life. Non-limiting examples of general industrial or infrastructure products that comprise epoxy-based materials that may be useful raw materials in the context of the present disclosure include poles, utility poles, composite tanks, composite pressure vessels, composite pipes, composite machinery frames, and composite robotic parts.Particle Size Reduction

[0069] The method provided herein may comprise subjecting a raw material comprising one or more epoxy-based polymers to a particle size reduction step, thereby producing a particulate starting material.

[0070] Epoxy -based polymers, and particularly fiber reinforced epoxy -based polymers, are generally insoluble or only sparingly soluble in most solvents. Without being bound to a particular theory, it is believed that the reaction rate of a base-mediated disassembly of an epoxy-based polymer is limited by the surface area of the particulate. It is therefore desirable to reduce the particle size of the epoxy-based polymer prior to contacting it with the basecomponent, in order to provide a larger overall surface area where the base-mediated reaction may occur.

[0071] The particle size reduction step may comprise subjecting the raw material to any suitable process known in the art for producing a particulate composition, such as shredding, grinding, filing, and / or milling (e.g., ball milling).

[0072] Powders or granulates of polymers may be characterized by standard techniques known to persons of ordinary skill in the field of physical sciences, such as e.g., dynamic light scattering according to 18013320:2020, and expressed in numerical values such as Dso and D90 (or another number between 1 and 100). As such, the value of Dnrefers the particle size of which n % of the measured sample is smaller.

[0073] While the particulate starting material may generally comprise particles of any size, it has been observed that the use of smaller particles facilitates more homogeneous mixing of the base component and the particulate starting material, and additionally facilitates a faster solid-phase reaction. The particulate starting material may, as a non-limiting example, have a particle size distribution characterized by D90 of from about 100 pm to about 10 mm. More typically, the particulate starting material has a particle size distribution characterized by a D90 of less than about 10 mm, less than about 5 mm, less than about 2 mm, or less than about 1 mm. The particulate starting material typically has a particle size distribution characterized by a D50 of less than about 5 mm, less than about 2 mm, or less than about 1 mm.

[0074] For example, the particulate starting material may have a particle size distribution characterized by a D90 of less than about 1000 pm, for example, less than about 900 pm, less than about 800 pm, less than about 700 pm, less than about 600 pm, less than about 500 pm, less than about 400 pm, less than about 300 pm, less than about 200 pm, or even less than about 100 pm. The particulate material typically has a particle size distribution characterized by a D90 of at least about 50 pm, for example, at least about 75 pm, at least about 100 pm, at least about 200 pm, at least about 250 pm, or at least about 500 pm. The particulate material may have a particle size distribution characterized by a D90 that falls within a range bounded by any two values listed above. For example, the particulate material may have a particle size distribution characterized by a D90 that falls within a range of from about 100 pm to about 1000 pm, or from about 200 pm to about 500 pm.

[0075] For example, the particulate starting material may have a particle size distribution characterized by a D50 of less than about 500 pm, for example, less than about 400 pm, less than about 300 pm, less than about 250 pm, less than about 225 pm, less than about200 pm, less than about 175 pm, less than about 150 pm, less than about 125 pm, or even less than about 100 pm. The particulate material typically has a particle size distribution characterized by a Dso of at least about 25 pm, for example, at least about 50 pm, at least about 75 pm, at least about 100 pm, at least about 150 pm, or at least about 200 pm. The particulate material may have a particle size distribution characterized by a Dso that falls within a range bounded by any two values listed above. For example, the particulate material may have a particle size distribution characterized by a Dso that falls within a range of from about 50 pm to about 300 pm, from about 75 pm to about 200 pm, or from about 100 pm to about 175 pm.Preparation of a Reaction Mixture

[0076] The method provided herein may comprise mixing a particulate starting material comprising an epoxy-based polymer with a solvent component and a base component to produce a reaction mixture.

[0077] The reaction mixture preferably comprises the base component in molar excess relative to the epoxy-based polymer. Stated equivalently, the reaction mixture preferably comprises the base component and the epoxy -based polymer in a molar ratio of at least 1 : 1. For example, the reaction mixture may comprise the base component and the epoxy-based polymer in a molar ratio of at least about 2: 1, at least about 3: 1, at least about 4: 1, at least about 5: 1, or at least about 6: 1 or greater. To avoid excess base at the completion of the reaction, the reaction mixture typically comprises the base component and the epoxy-based polymer in a molar ratio of no greater than about 10: 1, for example, no greater than about 8: 1, no greater than about 6: 1, or no greater than about 4: 1. The reaction mixture may comprise the base component and the epoxy-based polymer in a molar ratio that falls within a range bounded by any two values listed above. As non-limiting examples, the reaction mixture may comprise the base component and the epoxy -based polymer in a molar ratio of from 1 : 1 to about 8: 1, from about 2: 1 to about 6: 1, or from about 2: 1 to about 4: 1.

[0078] The reaction mixture preferably comprises a sufficient amount of solvent to homogenously disperse the particulate starting material within the reaction mixture. As an example, the reaction mixture may comprise the solvent component and the particulate starting material in a mass ratio of at least about 1 : 1, at least about 1.25: 1, at least about 1.5: 1, at least about 1.75: 1, at least about 2: 1, or at least about 2.5: 1. To avoid excessive solvent use, the reaction mixture typically comprises the solvent and the particulate starting material in a mass ratio of no greater than about 10: 1, for example, no greater than about 8: 1, no greater than about6: 1, no greater than about 4: 1, or no greater than about 3: 1. The reaction mixture may comprise the solvent component and the particulate starting material in a mass ratio that falls within a range bounded by any two values listed above. As non-limiting examples, the reaction mixture may comprise the solvent component and the particulate starting material in a mass ratio of from about 1 : 1 to about 10: 1, from about 1.5: 1 to about 6: 1, or from about 1.75: 1 to about 3: 1.

[0079] Homogenization of the Reaction Mixture

[0080] Preferably, the reaction mixture is a homogenous reaction mixture. As used herein, a reaction mixture is “homogenous” if it exhibits no visible separation between liquid phases, and any solid particulate phase (if present) is evenly distributed throughout the mixture.

[0081] The homogenous reaction mixture may, for example, be in form of an aqueous colloidal suspension wherein a solid particulate phase comprising an epoxy-based polymer is evenly suspended in an aqueous liquid phase.

[0082] The homogenous reaction mixture may be prepared by a homogenization step wherein the reaction mixture is heated. The reaction mixture is preferably heated to a temperature of at least about 100 °C. For example, the reaction mixture may be heated to a temperature of at least about 110 °C, at least about 120 °C, at least about 130 °C, at least about 140 °C, at least about 150 °C, at least about 160 °C, at least about 170 °C, or at least about 180 °C. The reaction mixture is typically heated to a temperature of no greater than about 300 °C, for example, no greater than about 275 °C, no greater than about 250 °C, no greater than about 225 °C, no greater than about 210 °C, or no greater than about 200 °C. The reaction mixture may be heated to a temperature that falls within a range bounded by any two values listed above. As non-limiting examples, the reaction mixture may be heated to a temperature of from about 100 °C to about 300 °C, from about 150 °C to about 250 °C, or from about 160 °C to about 200 °C.

[0083] The reaction mixture should be heated for a period sufficient to produce a homogenous mixture (e.g., a homogeneous colloidal suspension). For example, the homogenization step may comprise heating the reaction mixture for a period of at least about 5 minutes, at least about 10 minutes, at least about 15 minutes, at least about 30 minutes, at least about 45 minutes, at least about 1 hour, at least about 2 hours, at least about 3 hours, at least about 4 hours, or at least about 8 hours or more. Typically the homogenization step comprises heating the reaction mixture for no longer than about 24 hours, for example, no longer than about 12 hours, no longer than about 8 hours, or no longer than about 6 hours. Thehomogenization step may comprise heating the reaction mixture for a period of time bounded by any two values listed above. As non-limiting examples, the homogenization step may comprise heating the reaction mixture for a period of from about 5 minutes to about 8 hours, from about 1 hour to about 8 hours, or from about 3 hours to about 6 hours.

[0084] The homogenization step may comprise mixing the reaction mixture. The reaction mixture may be mixed using any appropriate technique known to those skilled in the art to promote an even, uniform distribution of the components of the mixture. For example, the homogenization step may comprise stirring the reaction mixture (for example, using a stir bar), vortexing the reaction mixture, or utilizing any other similar technique until an even distribution of the components is achieved.Solvent Removal

[0085] The method provided herein may comprise a solvent removal step wherein a solvent is removed from the reaction mixture, thereby producing a solid reaction mixture.

[0086] The solvent removal step preferably comprises removing most (at least about 50 % by weight) of the solvent component from the reaction mixture. For example, the solvent removal step may comprise removing at least about 50 %, at least about 60 %, at least about 70 %, at least about 80 %, at least about 85 %, at least about 90 %, or at least about 95 % by weight of the solvent component present in the reaction mixture.

[0087] The solvent may be removed using any suitable process known in the art. For example, the solvent may be removed by spray drying, film evaporation techniques (such as falling film evaporation, thin film evaporation, or wiped film evaporation), distillation techniques (such as vacuum distillation or rotary distillation), centrifugal evaporation, convection oven drying, or any other technique known to those skilled in the art.

[0088] As a non-limiting example, the solvent may be removed by heating the reaction mixture to a temperature sufficient to evaporate the desired fraction of the solvent. The reaction mixture may, for example, be heated to a temperature at or above the boiling point of the solvent.

[0089] For example, the solvent removal step may comprise heating the reaction mixture to a temperature of at least about 50 °C, at least about 60 °C, at least about 70 °C, at least about 80 °C, at least about 90 °C, at least about 100 °C, at least about 110 °C, or at least about 120 °C. The reaction mixture is typically heated to a temperature of no greater than about 200 °C during the solvent removal step, for example, no greater than about 170 °C, no greaterthan about 150 °C, no greater than about 140 °C, no greater than about 130 °C, no greater than about 120 °C, no greater than about 110 °C, or no greater than about 100 °C. The reaction mixture may be heated to a temperature that falls within a range bounded by any two values listed above. As non-limiting examples, the reaction mixture may be heated to a temperature of from about 50 °C to about 200 °C, from about 50 °C to about 150 °C, or from about 80 °C to about 100 °C. The reaction mixture should be heated for a period sufficient to evaporate the desired fraction of the solvent (for example, at least about 50 % by weight of the solvent). For example, the solvent removal step may comprise heating the reaction mixture for a period of at least about 5 minutes, at least about 10 minutes, at least about 15 minutes, at least about 30 minutes, at least about 45 minutes, at least about 1 hour, at least about 2 hours, at least about 3 hours, at least about 4 hours, or at least about 8 hours or more. Typically the solvent removal step comprises heating the reaction mixture for no longer than about 24 hours, for example, no longer than about 12 hours, no longer than about 8 hours, or no longer than about 6 hours. The solvent removal step may comprise heating the reaction mixture for a period of time bounded by any two values listed above. As non-limiting examples, the solvent removal step may comprise heating the reaction mixture for a period of from about 5 minutes to about 8 hours, from about 1 hour to about 8 hours, or from about 2 hours to about 6 hours.

[0090] The solvent removal step may be performed prior to the solid-phase reaction, which is described in further detail below. Alternatively, the solvent removal step and the solidphase reaction may be carried out simultaneously (i.e., as a single step). In such embodiments, the solvent removal step will be carried out at an elevated temperature as described below with respect to the solid-phase reaction (e.g., a temperature of at least about 200 °C) and for a duration as described below with respect to the solid-phase reaction (e.g., a period of at least about 5 minutes).Solid-Phase Reaction

[0091] The method provided herein may comprise conducting a solid-phase reaction within the solid reaction mixture, thereby producing a product mixture.

[0092] The solid-phase reaction step may comprise heating the solid-phase reaction mixture to an elevated temperature (for example, inside an oven). For example, the method may comprise heating the solid reaction mixture to a temperature of at least about 200 °C during the solid-phase reaction. For example, the solid-phase reaction mixture may be heated to a temperature of at least about 210 °C, at least about 220 °C, at least about 230 °C, at leastabout 240 °C, at least about 250 °C, at least about 260 °C, at least about 270 °C, or at least about 280 °C. The solid-phase reaction mixture is typically heated to a temperature of no greater than about 500 °C during the solid-phase reaction, for example, no greater than about 450 °C, no greater than about 400 °C, no greater than about 375 °C, no greater than about 350 °C, no greater than about 325 °C, or no greater than about 300 °C. The solid-phase reaction mixture may be heated to a temperature that falls within a range bounded by any two values listed above. As non-limiting examples, the solid-phase reaction mixture may be heated to a temperature of from about 200 °C to about 400 °C, from about 200 °C to about 325 °C, or from about 220 °C to about 300 °C.

[0093] The solid-phase reaction mixture is preferably heated for a period sufficient to drive the solid-phase reaction substantially to completion. For example, the method may comprise heating the solid-phase reaction mixture for a period of at least about 5 minutes, at least about 10 minutes, at least about 15 minutes, at least about 30 minutes, at least about 45 minutes, at least about 1 hour, at least about 2 hours, at least about 3 hours, at least about 4 hours, or at least about 8 hours or more. Typically the method comprises heating the solidphase reaction mixture for no longer than about 24 hours, for example, no longer than about 12 hours, no longer than about 8 hours, or no longer than about 6 hours. The method may comprise heating the solid-phase reaction mixture for a period of time bounded by any two values listed above. As non-limiting examples, the method may comprise heating the solidphase reaction mixture for a period of from about 5 minutes to about 4 hours, from about 15 minutes to about 3 hours, or from about 30 minutes to about 2 hours.Product Mixture

[0094] The methods provided herein may comprise recovering one or more desirable chemical products from the product mixture.

[0095] Non-limiting examples of desirable products that may be present in the product mixture include bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC, bisphenol Z, and derivatives thereof. For example, the product mixture may comprise bisphenol A.

[0096] Without being bound to a particular theory, it has been observed that conducting a solid-phase reaction as described herein will produce a relatively higher yield of desirable products (such as BP A) and a relatively lower yield of undesirable byproducts (such as phenol)as compared to liquid-phase processes previously known in the art. For example, the reaction may produce a BPA yield of at least about 10 %, at least about 25 %, at least about 50 %, at least about 75 %, at least about 80 %, at least about 85 %, at least about 90 %, or at least about 95 %, expressed as a fraction of the total potentially recoverable BPA present in the particulate starting material.

[0097] The following examples illustrate various aspects of the present invention. The examples should, of course, be understood to be merely illustrative of only certain embodiments of the invention and not to constitute limitations upon the scope of the invention which is defined by the claims that are appended at the end of this description.

[0098] Having described the disclosure in detail, it will be apparent that modifications and variations are possible without departing from the scope of the claims.EXAMPLES

[0099] The following non-limiting examples are provided to further illustrate the present disclosure.Example 1

[0100] A clear cast epoxy polymer was prepared by combining AIRSTONE 760E (epoxy resin) and AIRSTONE 766H (hardener) in a weight ratio of 100:32 according to the technical manual. The resulting polymer was ground using a Baltringen milling process to produce a particulate starting material having particle sizes within a range of from 100 pm to 3 mm.

[0101] Step la: Homogenization

[0102] The particulate starting material solvent (200 g) was combined with sodium hydroxide (100 g) and ethanol (700 g) in a reaction vessel and flushed with nitrogen. The mixture was stirred, and heat was applied until the mixture became homogenous. The resulting liquid reaction mixture was an almost clear, slightly yellow and homogeneous liquid.

[0103] Step lb: Solvent Removal

[0104] The liquid reaction mixture was dried in a rotary evaporator at 90 °C and a vacuum of 30 mbar. The mixture was observed to foam strongly while inside the evaporator. After 2 hours, a homogeneous yellowish solid was obtained.

[0105] Step 1c: Solid Phase Reaction

[0106] The homogeneous solid produced in Step lb was placed in an oven and exposed to a temperature of 270 °C for 90 minutes, during which a solid-phase reaction was conducted. The resulting product mixture was analyzed found to contain bisphenol A. Surprisingly, no byproducts such as phenol, isopropenylphenol or p-cumenol were present at observable levels in the product mixture.Example 2: Effect of Process Parameters on Bisphenol A Yield

[0107] A series of experiments was conducted to determine the effect of various process parameters on the yield of bisphenol A recovered from epoxy resin. The experiments followed a general procedure similar to that described in Example 1, with specific variations in reaction parameters as detailed below.

[0108] General Procedure

[0109] A clear cast epoxy polymer was prepared by combining AIRSTONE 760E (epoxy resin) and AIRSTONE 766H (hardener) in a weight ratio of 100:32 according to the technical manual. The resulting polymer was ground to produce a particulate starting material having particle sizes of either 250 pm or 800 pm.

[0110] Step 2a: Homogenization[OHl] The particulate starting material (approximately 2 g) was combined with a base component (approximately 1 g) and a solvent component (approximately 7 g) in a PTFE insert containing a magnetic stirring bar. The vessel was flushed with argon for 2 minutes, sealed in an autoclave, and placed in a preheated oven. The magnetic stirrer was set to 250 rpm. The homogenization temperature ranged from 155 °C to 195 °C , and the homogenization time was 4 hours.

[0112] Step 2b: Solvent Removal

[0113] After cooling overnight, the reaction product was transferred to a round bottom flask and washed three times with approximately 10 ml of ethanol. The solvent was removed using a rotary evaporator at 90 °C , 100 rpm, and 650 mbar until dryness (approximately 10 minutes), followed by 90 °C , 100 rpm, and 450 mbar for 7 minutes.

[0114] Step 2c: Solid Phase Reaction

[0115] The round bottom flask containing the dried reaction mixture was placed in a preheated oven where offgases were directed outside the oven. The solid-phase reaction was conducted at a temperature between approximately 220 °C and 260 °C for a period ranging from 3 to 8 hours, as specified in each experiment. After the specified reaction time, the flask was allowed to cool overnight in the oven.

[0116] Step 2d: Product Analysis

[0117] The reaction mixture was dissolved in 15 g of water and transferred to a 100 ml Duran bottle. The flask was washed three times with 8 g of water, and the washings were added to the bottle. 25 ml of methyl isobutyl ketone (MIBK) was added, followed by 6.8 g of 4N HC1 (or more if necessary). The mixture was extracted in an oven at 70 °C for 15 minutes with stirring at 1100 rpm. After cooling, the MIBK phase was separated, weighed, and analyzed by gas chromatography to determine the yield of bisphenol A.Example 3: Solvent Selection

[0118] The effect of solvent type on the yield of bisphenol A was investigated following the general procedure described in Example 2. Ethanol (96%) and methanol were compared as solvents while keeping other parameters constant. The results are presented in Table 1 below.Table 1: Effect of Solvent Type on Bisphenol A Yield

[0119] As shown in Table 1, both methanol and ethanol were effective to yield bisphenol A. It was also observed that methanol consistently yielded higher amounts of bisphenol A compared to ethanol under otherwise identical reaction conditions.Example 4: Base Selection

[0120] The effect of base type on the yield of bisphenol A was investigated following the general procedure described in Example 2. Sodium hydroxide (NaOH) and potassium hydroxide (KOH) were compared while keeping other parameters constant. The results are presented in Table 2 below.Table 2: Effect of Base Type on Bisphenol A Yield

[0121] As shown in Table 2, both sodium hydroxide (NaOH) and potassium hydroxide (KOH) were effective for the deconstruction of epoxy-based polymers under the conditions tested. It was also observed that yields of bisphenol A using NaOH were typically above 84%, while yields using KOH were substantially lower, ranging from approximately 10% to 28%. Example 5: Effect of Homogenization Temperature

[0122] The effect of homogenization temperature on the yield of bisphenol A was investigated following the general procedure described in Example 2. Homogenizationtemperatures of 155 °C, 175 °C , and 195 °C were compared while keeping other parameters constant. The results are presented in Table 3 below.Table 3: Effect of Homogenization Temperature on Bisphenol A YieldExample 6: Effect of Solid-Phase Reaction Time and Temperature

[0123] The effect of solid-phase reaction time and temperature on the yield of bisphenol A was investigated following the general procedure described in Example 2. Reaction times ranging from 3 to 8 hours and temperatures from 220 °C to 260 °C were compared while keeping other parameters constant. The results are presented in Table 4 below.Table 4: Effect of Solid-Phase Reaction Time on Bisphenol A Yield

[0124] As shown in Table 4, the duration of the solid-phase reaction affected the yield of bisphenol A. Extended reaction times beyond 6 hours appeared to result in lower yields, with the optimal reaction time being approximately 4-5 hours, where yields peaked at 95.1%. Without being bound to a particular theory, it is believed that the decrease in yield with longer reaction times may be attributable to decomposition of the desired product or formation of secondary products at elevated temperatures over extended periods.Example 7: Effect of Particle Size

[0125] The effect of epoxy resin particle size on the yield of bisphenol A was investigated following the general procedure described in Example 2. Particle sizes of 250 pm and 800 pm were compared while keeping other parameters constant. The results are presented in Table 5.Table 5: Effect of Particle Size on Bisphenol A Yield

[0126] As shown in Table 5, the particle size of the epoxy resin did not impact the yield of bisphenol A under the conditions tested. Both 250 pm and 800 pm particle sizes resulted in high yields of bisphenol A, explainable by the fact that in all experiments, clear or almost clear single-phase liquids were present after the homogenization step. This finding is significant because it suggests that extensive grinding or milling of the epoxy resin may not be necessary to achieve high yields, potentially reducing the energy consumption and cost associated with the particle size reduction step in an industrial process.Example 8: Effect of Base-to-Resin Ratio

[0127] The effect of the base-to-resin ratio on the yield of bisphenol A was investigated following the general procedure described in Example 2. Different amounts of sodium hydroxide were used while keeping other parameters constant. The results are presented in Table 6.Table 6: Effect of Base-to-Resin Ratio on Bisphenol A Yield

[0128] As shown in Table 6, the base-to-resin ratio had a substantial impact on the yield of bisphenol A. When the ratio was below 2, yields were significantly reduced, particularly at longer reaction times. Optimal results were achieved with a base-to-resin ratio higher than 3, where yields consistently exceeded 80 % and often reached above 90 %. These findings indicate that an adequate amount of base is crucial for efficient deconstruction of epoxy -based polymers, but excessive amounts do not necessarily improve yields and may even be slightly detrimental. Example 9: Effect of Solvent-to-Resin Ratio

[0129] The effect of the solvent-to-resin ratio on the yield of bisphenol A was investigated following the general procedure described in Example 2. Different amounts ofethanol were used while keeping other parameters constant. The results are presented in Table 7.Table 7: Effect of Solvent-to-Resin Ratio on Bisphenol A Yield

[0130] As shown in Table 7, the solvent-to-resin ratio had a notable impact on the yield of bisphenol A. Unexpectedly, it was observed that lower solvent-to-resin ratios (around 1.7- 2.0) appeared to result in higher yields compared to standard (around 3.5) or elevated (around 7.0) ratios, particularly when the solid-phase reaction time was 4 hours. The highest yield (99.7%) was achieved with a solvent-to-resin ratio of 2.05.

[0131] In view of the above, it will be seen that the several objects of the disclosure are achieved and other advantageous results attained. As various changes could be made in theabove products and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

[0132] When introducing elements of the present disclosure or the preferred embodiment s) thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. Additionally, references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0133] The terms “upstream” and “downstream” are understood relatively to the normal direction of circulation of a fluid in a conduit.

[0134] The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The term “consisting of’ is intended to be exclusive and to encompass only the listed elements. It will be understood that if an embodiment is described as “comprising” one or more elements, an embodiment “consisting of’ the same elements is also within the scope of the present disclosure as if expressly described herein.

[0135] The phrases, unless otherwise specified, “consists essentially of’ and “consisting essentially of’ do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the present disclosure, additionally, they do not exclude impurities and variances normally associated with the elements and materials used.

[0136] Numerical ranges used herein include the numbers recited in the range. For example, the numerical range “from 1 weight percent to 10 weight percent” includes 1 weight percent and 10 weight percent within the recited range.

[0137] For the sake of brevity, only some ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its ownlower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0138] All numerical values within the detailed description herein are modified by “about” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.

[0139] The specific embodiments described herein have been illustrated by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

[0140] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for (perform)ing (a function)...” or “step for (perform)ing (a function)...”, it is intended that such elements are to be interpreted under 35 U.S.C. § 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. § 112(f).

[0141] While the present disclosure has been described with respect to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the present disclosure.

Claims

CLAIMSWhat is claimed is:

1. A method for deconstructing an epoxy -based polymer, the method comprising:(1) combining a particulate starting material comprising an epoxy-based polymer with a solvent component and a base component to produce a homogenous reaction mixture;(2) removing at least about 50 % by weight of the solvent component from the reaction mixture, thereby producing a solid reaction mixture; and(3) conducting a solid-phase reaction within the solid reaction mixture, thereby producing a product mixture.

2. The method of claim 1 wherein the solvent component comprises a polar protic solvent.

3. The method of claim 1 or 2 wherein the solvent component is miscible with water.

4. The method of any one of claims 1 to 3 wherein the solvent component comprises an aliphatic Ci-Cs alcohol.

5. The method of claim 4 wherein the solvent component comprises methanol.

6. The method of claim 4 wherein the solvent component comprises ethanol.

7. The method of any one of claims 1 to 6 wherein the base component comprises an aqueous base.

8. The method of claim 7 wherein the base component comprises an oxygen-containing base.

9. The method of claim 8 wherein the base component comprises a base selected from the group consisting of sodium hydroxide and potassium hydroxide.

10. The method of claim 7 wherein the base component comprises a nitrogen-containing base.

11. The method of claim 10 wherein the base component comprises a base selected from the group consisting of lithium diisopropylamide (LDA), lithium diethylamide (LDEA), sodium amide, lithium bis(trimethylsilyl)amide, triethylamine, trimethylamine, diethylamine, dimethylamine, isopropylamine, pyridine and ammonia.

12. The method of any one of claims 1 to 11 wherein the particulate starting material has a particle size distribution characterized by a D90 of less than about 1000 pm.

13. The method of any one of claims 1 to 12 wherein the particulate starting material comprises a bisphenol A based polymer.

14. The method of claim 13 wherein the product mixture comprises bisphenol A.

15. The method of any one of claims 1 to 14 comprising: removing at least about 80 % by weight of the solvent component from the reaction mixture, thereby producing a solid reaction mixture.

16. The method of any one of claims 1 to 15 wherein removing the solvent component from the reaction mixture comprises heating the reaction mixture to a temperature of from about 50 °C to about 150 °C for a period of from about 1 hour to about 8 hours.

17. The method of any one of claims 1 to 16 wherein the solid-phase reaction comprises heating the solid reaction mixture to a temperature of at least about 200 °C.

18. The method of claim 17 wherein the solid-phase reaction comprises heating the solid reaction mixture to a temperature of from about 200 °C to about 325 °C for a period of from about 30 minutes to about 2 hours.

19. The method of any one of claims 1 to 18 wherein the particulate starting material is obtained by subjecting a raw material comprising one or more epoxy -based polymers to a particle size reduction step.

20. The method of any one of claims 1 to 19 further comprising recovering bisphenol A from the product mixture.

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