Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/50—Amines
  • C08G59/504—Amines containing an atom other than nitrogen belonging to the amine group, carbon and hydrogen
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/02—Separating plastics from other materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/68—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the catalysts used
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/06—Recovery or working-up of waste materials of polymers without chemical reactions
  • C08J11/08—Recovery or working-up of waste materials of polymers without chemical reactions using selective solvents for polymer components
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
  • C08J11/18—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material
  • C08J11/22—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material by treatment with organic oxygen-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
  • C08J5/0405—Reinforcing macromolecular compounds with loose or coherent fibrous material with inorganic fibres
  • C08J5/043—Reinforcing macromolecular compounds with loose or coherent fibrous material with inorganic fibres with glass fibres
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/24—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs
  • C08J5/241—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs using inorganic fibres
  • C08J5/244—Impregnating materials with prepolymers which can be polymerised in situ, e.g. manufacture of prepregs using inorganic fibres using glass fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/02—Separating plastics from other materials
  • B29B2017/0213—Specific separating techniques
  • B29B2017/0293—Dissolving the materials in gases or liquids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins

Definitions

• thermoset resin compositions which are fully recyclable; as well as prepregs, composites and articles comprising it.
• the present invention also refers to a recycling process of the thermoset epoxy resin composition as well as the reinforcement phase from the composite or the article containing the recyclable thermoset epoxy resin composition.
• Composite materials usually consist of a reinforcement phase, generally comprising continuous or discontinuous fibres, and a matrix phase, generally containing a thermoset or thermoplastic polymer.
• the matrix material surrounds and supports the reinforcement material by maintaining their relative positions, meanwhile the reinforcement material imparts their special mechanical and physical properties to enhance the matrix properties.
• thermosets are typically preferred over thermoplastics in high demanding applications where mechanical and thermal stability are important.
• the crosslinked molecular structure of thermosets is responsible for their enhanced performance, but it goes at the expenses of becoming non-meltable, insoluble and unsuitable for reprocessing and/or recycling.
• thermoset composites the resin matrix cures or hardens into a given shape through an irreversible chemical reaction. Which means that once a thermoset composite is formed, it cannot be remoulded or reshaped (that is, it is not reprocesable). Because of this, the recycling of thermoset composites is extremely difficult. Usually, the resin is removed by pyrolysis to recover the reinforcement phase. This process is time and energy-consuming and not environmentally friendly. Furthermore, the properties of the reinforcement phase can be affected.
• thermoset crosslinked epoxy resins and composites/articles containing it.
• an attempt to provide reprocesable epoxy thermoset composites was performed by Leibler et al. in the US2013/0300020.
• Such composites comprise a reinforcement material and a matrix phase containing a thermosetting resin, an anhydride based hardener, and a catalyst which remains in the composite after its manufacturing.
• the recycling process of an article containing the thermoset crosslinked epoxy resin composite involves first a pulverization (grinding) step or a deformation step by the application of mechanical forces. After that, it is mixed with virgin epoxy-resin for the preparation of thermoset epoxy resin article with less demanding properties. Therefore, again the recycling process impairs and/or significantly alter the properties of the thermoset epoxy resin composition and the article obtained using it.
• thermoset crosslinked composites have been disclosed in the state of the art, which implies a chemical agent that disrupt the covalent crosslinks of the thermoset resin obtaining a soluble thermoplastic polymer.
• this method does not permit the recovery of the initial properties of the thermoset resin composition and also involves the use of strong chemical agents such as trialkyl and triaryl phosphine, and alkali metal aluminium hydride to disrupt the covalent bonds.
• CN11015544 discloses a thermoset crosslinked epoxide resin composition prepared mixing an epoxy resin, a dicarboxylic acid monomer, epoxy resin curing agent, a catalyst, and a self-healing accelerator.
• US2003064228 discloses epoxy resin compositions for a fiber-reinforced composite material containing an alicyclic epoxy resin, a polyamine and a latent acid catalyst which can dissolve in the alicyclic epoxy resin or in the polyamine.
• J. Polymer 2022, 239, 124457 it is reported a methodology to manipulate the dynamic properties of aromatic disulfide containing vitrimers by changing the hardener structure, stoichiometry or catalyst quantity.
• EP2949679 relates to epoxy composites comprising a reinforcement phase comprising fibers, and a matrix phase comprising a cured epoxy resin obtainable by mixing an epoxide-functionalized resin with a functionality equal to or higher than 2 with a cross-linking agent and curing the reaction mixture, this step being performed in the absence of a catalyst.
• J Polymer 2022, 248, 124801 discloses self-healed vitrimers from a bisphenol A type epoxy resin, suberic acid, 4,4'-diaminodiphenyl disulfide, and tetrabutylammonium bromide resulting in a carboxylic acid-extended epoxy resin containing beta-hydroxyl esters and disulfide bonds.
• thermoset crosslinked epoxy resin composition that can be recycled without compromising its physical and chemical properties and neither the properties of the reinforcement material containing fibres.
• thermoset crosslinked epoxy resin composition obtainable by a method that comprises mixing an epoxide-functionalised resin with a cross-linking agent and a catalyst; and curing the mixture thus obtained, with the proviso that the cross-linking agent comprises an aromatic disulphide bond.
• thermoset crosslinked epoxy resin composition obtainable by a process that comprises mixing an epoxide-functionalised resin with a functionality equal to or higher than 2, with a cross-linking agent of formula (I) containing an aromatic disulphide bond, and a catalyst as defined herein; and followed by a curing step, has recyclable properties without compromising its physical and chemical properties.
• thermoset resin composition of the present invention are also recovered without alteration of its physical and chemical properties under mild conditions and without the use of mechanical forces or grinding methods.
• the recycling process of a composite and/or article comprising the thermoset crosslinked epoxy resin composition of the invention is performed by separating the thermoset crosslinked epoxy resin composition from the reinforcement phase in the presence of a solvent under mild conditions without the need of using strong reducing and/or oxidizing agents, only by the use such solvents.
• thermoset crosslinked epoxy resin composition as well as the reinforcement phase thus recovered can be directly re-sold or alternative re-used and/or repurposed without hindering the quality/properties of the finally obtained composites/articles containing it.
• thermoset crosslinked epoxy resin composition of the present invention are also reprocesable, and reparable.
• the thermoset crosslinked epoxy resin composition of the present invention allows preparing re-shapable and reprocesable composites and/or articles containing them, if desired, by applying suitable temperature and/or pressure conditions, without compromising the physical, chemical, and mechanical properties of the product.
• the thermoset composites comprising the thermoset crosslinked epoxy resin composition of the present invention are also repairable by applying suitable temperature/pressure conditions on the damaged area.
• thermoset crosslinked epoxy resin composition of the present invention comprising bis(4-aminophenyl)disulphide of formula (III) further has a transient mechano-chromic behaviour. It happens when the composite containing it receives an impact, then a color change in the visible region of the EM spectrum is observed on the damaged area. This additional property confers to the composite of the invention a great value because it permits detecting damage by simple visual inspection.
• thermoset crosslinked epoxy resin composition of the present invention allows preparing intermediate prepregs for the preparation of composites that are partially or completely cured with improved handling properties.
• the prepregs pre-impregnated with thermoset crosslinked epoxy resin composition completely cured of the present invention are particularly advantageous because allows increasing the time between the manufacturing date of the prepreg and its processing date without altering the re-shapable, reprocesable and repairable properties of the thermoset resin of the present invention.
• enduring prepreg there is no time limitation, and at any time the enduring prepreg can be processed for the preparation of composites and subsequently articles containing it.
• thermoset crosslinked epoxy resin composition of the present invention and the prepregs, composites and articles containing it represent a great advance in the field of thermoset materials.
• thermoset crosslinked epoxide resin composition obtainable by a method comprising:
• Ar-S-S-Ar (I) at a molar ratio between the epoxide groups of the epoxy-functionalised resin and the epoxide-reactive functional moieties of the cross-linking agent of formula (I) from the stoichiometric to a two-fold excess of epoxide reactive functional group;
• thermoset crosslinked epoxide resin reaches a glass transition temperature value which is equal to or higher than 10°C but equal to or lower than the maximum glass transition temperature
• Ar means a ring system from 5 to 14 carbon atoms, the system comprising 1-3 rings, where:
• the rings are saturated, partially unsaturated, or aromatic
• the rings are isolated, partially, or totally fused, at least one of the carbon atoms forming the aryl moiety is substituted by an epoxide-reactive functional moiety selected from the group consisting of: -NHRw, -NH-NHRw, -CO-NH-NHRw, -COOH, -SH, -OH, -00- NHRw, -NCN-NH-NHRw, wherein the asterisk denotes the carbon atom through which the epoxide-reactive moiety binds to the ring system, and the remaining carbon atoms are optionally substituted by one or more moieties independently selected from the group consisting of (C1-C20) alkyl, (Cs-Cujaryl, -OR2, -(C0)R3, -0(C0)R4, -(SO)Rs, -NH-CO- Re, -COOR7, -NRsRg, -NO2, and halogen;
• R2 to Rio are the same or different, and are selected from the group consisting of: -H, (Ci-C2o)alkyl, and phenyl; provided that:
• Ar comprises at least one aromatic ring
• Ar is bonded to the -S- atom through the aromatic ring.
• the third aspect of the invention relates to a prepreg comprising: (a') a reinforcement phase comprising fibres, and (b’) a matrix phase comprising the thermoset crosslinked epoxide resin composition as defined in the first aspect of the invention.
• the fourth aspect of the invention relates to an article comprising the thermoset crosslinked epoxy resin.
• the article comprises one or more composites of the second aspect of the invention; or one or more prepregs of the third aspect of the invention.
• the fifth aspect of the invention relates to a process for recycling the thermoset crosslinked epoxy resin composition of the first aspect of the invention and the reinforcement phase comprising fibres from the composite of the second aspect of the invention, or the prepreg of the third aspect of the invention, or from the article of the fourth aspect of the invention, wherein the process comprises immersing the composite or the article in a solvent or mixture of solvents having a boiling temperature above the glass transition temperature of the composite and a Hansen solubility parameter (Ra) equal to or lower than 7.5 measured by equation (1):
• Ra 2 4(5DI-5D 2 ) 2 + (6P1-6P2) 2 + (6H1-6H2) 2 (eq. 1)
• thermoset crosslinked epoxy resin composition for dispersion expressed in MPa 1/2
• 5D2 the solubility parameter of the solvent or mixture of solvents for dispersion expressed in MPa 1/2
• 5P1 the solubility parameter of the thermoset crosslinked epoxy resin composition for polars expressed in MPa 1/2 ,
• thermoset crosslinked epoxy resin composition for hydrogen-bonding expressed in MPa 1/2
• thermoset crosslinked epoxy resin composition of the first aspect of the invention it is also part of the invention the processes for the preparation of the thermoset crosslinked epoxy resin composition of the first aspect of the invention, the thermoset composite of the second aspect of the invention, the prepreg of the third aspect of the invention, and the article of the fourth aspect of the invention.
• percentage (%) by weight or “% w/w” have the same meaning and are used interchangeable.
• percentage by weight refers to the percentage of an ingredient/component/compound in relation to the total weight of the final mixture/product/resin/composite. For instance, when referred to the thermoset crosslinked epoxy resin composition comprised in the matrix phase, is estimated determining the amount of the thermoset crosslinked epoxy resin composition with respect to the total weight of the matrix phase and the resulting value is multiplied by 100.
• the present invention provides a recyclable, thermoset crosslinked epoxy resin composition, prepregs, composites and articles comprising it.
• thermoset crosslinked epoxy resin composition of the present invention is separated and recovered from the reinforcement material of the composites/prepreg/articles containing it without altering its chemical and physical properties and being appropriate for its re-use. Furthermore, the thermoset crosslinked epoxy resin composition of the present invention is also reprocesable and reparable.
• thermoset crosslinked epoxy resin composition and composites/articles containing it are capable of changing its form, applying pressure and heat.
• the selection of specific pressure and heat conditions will depend on the specific nature of the material and shape of final part. Forms part of the routine tasks of the skilled person in the art the selection of appropriate pressure and heat conditions.
• the term "reparable” is to be understood as that the thermoset crosslinked epoxy resin composition and composites/articles containing it are capable of restoring the initial shape/form after suffering a damage, applying pressure and heat.
• the selection of specific pressure and heat conditions will depend on the extension and severity of the caused damage, as well as the specific nature of the material and shape of final part. Forms part of the routine tasks of the skilled person in the art the selection of appropriate pressure and heat conditions.
• the term “resin” means any polymer, oligomer or monomer comprising two or more epoxide groups.
• the term “polymer” means a molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass.
• the term “oligomer” means a molecule of intermediate relative molecular mass, the structure of which essentially comprises a small plurality of units derived, actually or conceptually, from molecules of lower relative molecular mass.
• the term “monomer” means a molecule which can undergo polymerization, thereby contributing constitutional units to the essential structure of a macromolecule.
• cross-linked or “cross-linking” refer in the synthetic polymer science field, the use of cross-links to promote a difference in the physical properties of the polymers.
• cross-links refers to bonds that link one polymer chain to another or different parts of the same polymer and these bonds can be covalent or ionic bonds.
• cross-linker or “cross-linking agent” refers to compound having the ability to cross-link the polymer chains.
• thermoset crosslinked epoxy resin composition is obtainable by the method as disclosed herein below and above.
• the expressions “obtainable”, “obtained” and equivalent expressions are used interchangeably, and in any case, the expression “obtainable” encompasses the expression “obtained”.
• thermoset crosslinked epoxy resin composition is obtainable by:
• Ar-S-S-Ar (I) at a molar ratio between the epoxide groups of the epoxy-functionalised resin and the epoxide-reactive functional moieties of the cross-linking agent of formula (I) from the stoichiometric to a two-fold excess of epoxide reactive functional group;
• thermoset crosslinked epoxide resin reaches a glass transition temperature value which is equal to or higher than 10°C but lower or equal than the maximum glass transition temperature
• Ar means a ring system from 5 to 14 carbon atoms, the system comprising 1-3 rings, where:
• the rings are saturated, partially unsaturated, or aromatic
• the rings are isolated, partially, or totally fused, at least one of the carbon atoms forming the aryl moiety is substituted by an epoxide-reactive functional moiety selected from the group consisting of: -NHRw, -NH-NHRw, -CO-NH-NHRw, -COOH, -SH, -OH, -CO- NHRw, -NCN-NH-NHRw, wherein the asterisk denotes the carbon atom through which the epoxide-reactive moiety binds to the ring system, and the remaining carbon atoms are optionally substituted by one or more moieties independently selected from the group consisting of (C1-C20) alkyl, (Cs-C jaryl, -OR2, -(C0)R3, -0(C0)R4, -(SO)Rs, -NH-CO- Re, -COOR7, -NRsRg, -NO2, and halogen;
• Ar comprises at least one aromatic ring
• Ar is bonded to the -S- atom through the aromatic ring.
• alkyl refers to a saturated straight, or branched hydrocarbon chain which contains the number of carbon atoms specified in the description or claims. Examples include, among others, the group methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl.
• halogen refers to fluorine, chlorine, and bromine.
• functionality equal to or higher than 2 when referred to the epoxide- functionalised resin, means that each resin molecule comprises at least two epoxide groups.
• molar ratio refers to the relation of moles of epoxide groups of the epoxide-functionalised resin vs. the moles of epoxide reactive functional moieties of the cross-linking agent (such as for example the compound of formula (I)) as defined in the present invention.
• the term "stoichiometric ratio" refers to such ratio that all the reagents are completely consumed during the process. Then, there is neither deficiency nor excess of reagents.
• the sentence "two-fold excess of epoxide reactive group” is determined starting from the stoichiometric ratio and multiplying the number of moles related to the epoxide reactive groups by 2. For instance, when the epoxide reactive group is a -NH2 group, the stoichiometric ratio between the epoxide groups of the resin and -NH2 is 2: 1 . From this, and considering how it is estimated, the "two-fold excess” ratio for the case that the epoxide reactive group is -NH2 will be 1 :1.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (i) the epoxide-functionalised resin with a functionality equal to or higher than 2 consists of a single epoxide-functionalised type resin.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (i) the epoxide-functionalised resin with a functionality equal to or higher than 2 consists of a single epoxide-functionalised type resin selected from the group consisting of difunctional (thus having two epoxide groups), trifunctional (thus having three epoxide groups), tetrafunctional epoxide-functionalised resins (thus having four epoxide groups).
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (i) the epoxide-functionalised resin with a functionality equal to or higher than 2 consists of a single epoxide-functionalised type resin selected from the group consisting of a difunctional epoxy resin and tetrafunctional epoxy resin.
• epoxide-functionalised resin with a functionality equal to or higher than 2 are: Bisphenol A diglycidyl ether, Bisphenol F diglycidyl ether, tetrabromobisphenol A diglycidyl ether, propylene glycol diglycidyl ether, butylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1 ,6-hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether
• Illustrative non-limitative examples of tri-functional epoxy resins with a functionality equal to or higher than 2 are: triglycidyl ether of para-aminophenol, and triglycidyl meta-aminophenol.
• Illustrative non-limitative examples of tetra-functional epoxy resins are N,N,N',N'-tetraglycidyl methylene dianiline, N,N, N', N'-tetraglycidyl-m-xylene diamine, and pentaerythritol tetraglycidyl ether.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture of two or more epoxide-functionalised resins, said resins being independently selected from the group consisting of difunctional, trifunctional, and tetrafunctional epoxide-functionalised resins.
• the functionality of the resulting mixture is calculated as the weighted average from the functionalities of the epoxide-functionalised resins forming the mixture.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a difunctional epoxy resin or a mixture comprising one or more difunctional epoxy resins.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a bisphenol epoxy resin.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide- functionalised resin with a functionality equal to or higher than 2 is a mixture of epoxy resins comprising a bisphenol epoxy resin.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is the difunctional epoxy-resin bisphenol A diglycidyl ether or bisphenol F diglycidyl ether. In one embodiment, the thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide- functionalised resin with a functionality equal to or higher than 2 is a mixture comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture of difunctional epoxy resins. In one embodiment, the thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin a mixture of difunctional epoxy resins with a functionality equal to or higher than 2 comprising a bisphenol epoxy resin. In one embodiment, the thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide- functionalised resin with a functionality equal to or higher than 2 is a mixture of two difunctional epoxy resins comprising a bisphenol epoxy resin.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture of two difunctional epoxy resins comprising a bisphenol epoxy resin from 60% to 99% by weight.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture of two difunctional epoxy resins comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether. In one embodiment, the thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture of two difunctional epoxy resins comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether % w/w from 60% to 99%.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture of two difunctional epoxy resins comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether % w/w from 70% to 90%.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether and 1 ,4-butanediol diglycidyl ether.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether and neopentyl glycol diglycidyl ether.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin is obtainable by the process comprising: (a) mixing a difunctional epoxy resin or a mixture of difunctional epoxy resins with a cross-linking agent of formula (I) as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein in step (I) the epoxide-reactive functional group of the epoxy-functionalised resin with a functionality equal to or higher than 2 is -NHRw, or -NH-NHRw, wherein Rw is as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein in step (I) the epoxide-reactive functional group of the epoxyfunctionalised resin with a functionality equal to or higher than 2 is -NH2.
• thermoset crosslinked epoxy is obtainable by a method wherein in step (I) the epoxide-reactive functional group of the epoxy-functionalised resin with a functionality equal to or higher than 2 — NH2, the molar ratio between the epoxide groups of the epoxide-functionalised resin and the epoxidereactive functional moieties of the cross-linking agent is comprised from 2:1 to 1 :1.
• the thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the crosslinking agent is a compound of formula (I) Ar-S-S-Ar wherein: Ar means a ring system from 5 to 14 carbon atoms, the system comprising 1-3 rings, where: the rings are saturated, partially unsaturated, or aromatic; the rings are isolated, partially, or totally fused, at least one of the carbon atoms forming the aryl moiety is substituted by an epoxide-reactive functional moiety selected from the group consisting of: -NHR10, -NH-NHR10, -CO-NH-NHRw, -COOH, -SH, -OH, -CO-NHRw, -NCN-NH-NHR10, wherein the asterisk denotes the carbon atom through which the epoxide-reactive moiety binds to the ring system, and the remaining carbon atoms are optionally substituted by one or more moieties
• the term “Ar” and “aryl” and “aryl moiety” have the same meaning and are used interchangeable. They refer to a ring system from 5 to 14 carbon atoms, the system comprising 1-3 rings, as defined herein above and below. Further, the term “isolated” rings means that the ring system is formed by two or three rings and said rings are bound via a bond from the atom of one ring to the atom of the other ring. The term “isolated” also embraces the embodiment in which the ring system has only one aromatic ring, such as a phenyl.
• the term "totally fused” means that the ring system is formed by two or three rings in which two or more atoms are common to two adjoining rings. Illustrative non- limitative examples are 1 ,2,3,4-tetrahydronaphthyl, 1-naphthyl, 2-naphthyl, anthryl, or phenanthryl.
• the term “partially fused” means that the ring system is formed by three rings, being at least two of said rings totally fused (i.e. two or more atoms being common to the two adjoining rings) and the remaining ring(s) being bound via a bond from the atom of one ring to the atom of one of the fused rings.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I), the compound of formula (I) is one wherein Ar is a phenyl moiety.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the compound of formula (I) is one of formula (II) wherein: R1 and R/ are independently selected from the group consisting of: -H, (Ci-C2o)alkyl, (C5-
• R2 to Rg are the same or different and are selected from the group consisting of: -H, (Ci-C2o)alkyl, and (Cs-Cujaryl; and m is 4.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (i) the compound of formula (I) is one of formula (II) wherein Ri and R/ are the same.
• thermoset epoxy resin composition is obtainable by a method wherein in step (i) the compound of formula (I) is one of formula (II) wherein the -NH2 moieties are in ortho-position.
• ortho-position refers to a compound with substituents at the positions 1 and 2 on an aromatic ring.
• the symbol for ortho- is 0- or 1,2-.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (i) the compound of formula (I) is one of formula (II) wherein R1 and R/ are hydrogen.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (i) the compound of formula (I) is a compound of formula (III), which is the bis(4-aminophenyl)disulphide:
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (i) the compound of formula (I) is a compound of formula (IV), which is the bis(2-aminophenyl)disulphide:
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (i) the compound of formula (I) is a mixture of a compound of formula (III), which is the bis(4- aminophenyl)disulphide; and the compound of formula (IV), which is the bis(2-aminophenyl)disulphide.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein step (i) comprises at least one Lewis acid catalyst.
• the term "catalyst” refers to a compound which can reduce the activation energy of a reaction without being used up itself, without itself being consumed during the reaction.
• the catalyst remains in the thermoset epoxy resin composition modifying the final recyclability of the thermoset crosslinked epoxy resin.
• thermoset crosslinked epoxy is obtainable by a method wherein in step (i) the catalyst is one or more Lewis acids.
• Lewis acids refers to an atom, ion, or molecule with an incomplete octet of electrons capable of accepting a pair of electrons of a Lewis base.
• thermoset crosslinked epoxy is obtainable by a method wherein in step (i) the catalyst is one or more Lewis acids selected from the group consisting of metal halide, metalloid halide, metal complex with carboxylate ligand, trihalide metalloid adduct, and organometallic-Lewis acid complex and the halide is selected from the group consisting of fluoride, chloride, bromide, and iodide; the metal is selected from the group consisting of an alkali metal, an alkaline earth metal, a transition metal, a lanthanoid metal, and an actinoid metal; and the metalloid is selected from the group consisting of boron, silicon, arsenic, germanium, and lead.
• the catalyst is one or more Lewis acids selected from the group consisting of metal halide, metalloid halide, metal complex with carboxylate ligand, trihalide metalloid adduct, and organometallic-Lewis acid complex and the halide is selected from the group consisting of flu
• thermoset crosslinked epoxy is obtainable by a method wherein in step (i) the catalyst is selected from the group consisting of alkali metal halide, metalloid halide, metal complex with carboxylate ligand, trihalide metalloid adduct and a mixture thereof.
• the thermoset crosslinked epoxy is obtainable by a method wherein in step (i) the catalyst is selected from the group consisting of boron trifluoride ethylamine, chromium (III) 2-ethylhexanoate, zinc chloride and zinc (II) 2-ethylhexanoate and mixture thereof.
• thermoset crosslinked epoxy is obtainable by a method wherein in step (i) the amount of the catalyst is from 0.2% to 3% weight ratio.
• thermoset crosslinked epoxy is obtainable by a method wherein step (i) is performed by mixing a mixture of difunctional epoxy resins, the mixture comprising a bisphenol epoxy resin, with a crosslinking agent of formula (I) as defined above, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (i) is performed by mixing a mixture of two difunctional epoxy resins, the mixture comprising a bisphenol epoxy resin, with a cross-linking agent of formula (I) as defined above, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (i) is performed by mixing a mixture comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether with a cross-linking agent of formula (I) as defined above, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether; and 1 ,4-butanediol diglycidyl ether, with a cross-linking agent of formula (I) as defined above, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether; and neopentyl glycol diglycidyl ether, with a cross-linking agent of formula (I) as defined above, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a difunctional epoxy resin or mixture of difunctional epoxy resins with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of difunctional epoxy resins with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of difunctional epoxy resins, the mixture comprising a bisphenol epoxy resin, with a crosslinking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of two difunctional epoxy resins, the mixture comprising a bisphenol epoxy resin, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of bisphenol A diglycidyl ether or bisphenol F diglycidyl ether; and 1 ,4-butanediol diglycidyl ether, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of bisphenol A diglycidyl ether or bisphenol F diglycidyl ether; and neopentyl glycol diglycidyl ether, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a difunctional epoxy resin or mixture of difunctional epoxy resins with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety where uniquely one carbon atom of the ring is substituted, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of difunctional epoxy resins with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of difunctional epoxy resins, the mixture comprising a bisphenol epoxy resin, with a crosslinking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of two difunctional epoxy resins, the mixture comprising a bisphenol epoxy resin, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of bisphenol A diglycidyl ether, or bisphenol F diglycidyl ether; and 1 ,4-butanediol diglycidyl ether, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of bisphenol A diglycidyl ether, or bisphenol F diglycidyl ether; and neopentyl glycol diglycidyl ether, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a difunctional epoxy resin or mixture of difunctional epoxy resins with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety where uniquely one carbon atom of the ring is substituted with an -NH2 moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of difunctional epoxy resins with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted with an -NH2 moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of difunctional epoxy resins, the mixture comprising a bisphenol epoxy resin, with a cross- linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted with an -NH2 moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of two difunctional epoxy resins, the mixture comprising a bisphenol epoxy resin, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted with an -NH2 moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of bisphenol A diglycidyl ether, or bisphenol F diglycidyl ether; and 1 ,4-butanediol diglycidyl ether, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted with an -NH2 moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy is obtainable by a method wherein step (I) is performed by mixing a mixture of bisphenol A diglycidyl ether, or bisphenol F diglycidyl ether; and neopentyl glycol diglycidyl ether, with a cross-linking agent of formula (I) as defined above, wherein Ar is a phenyl moiety, where uniquely one carbon atom of the ring is substituted with an -NH2 moiety, and a catalyst as defined above.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein the curing step (ii) comprises curing the mixture obtained in step (I) at a temperature from 10°C to 200°C for a period of time such that the thermoset crosslinked epoxide resin reaches a glass transition temperature value which is equal to or higher than 10°C but equal to or lower than the maximum glass transition temperature.
• thermoset crosslinked epoxy is obtainable by a method wherein the curing step (ii) is performed at a temperature from 10°C to 200 °C for a period of time such that the resin reaches at least 25% of the maximum Tg value to obtain a thermoset crosslinked epoxy resin composition partially cured. Commonly, the time required for reaching the at least 25% of maximum Tg value to obtain a thermoset crosslinked epoxy resin composition partially cured.
• thermoset crosslinked epoxy is obtainable by a method wherein the curing step (ii) is performed at a temperature from 10°C to 200 °C for a period of time such that the resin reaches at maximum Tg value to obtain a thermoset crosslinked epoxy resin composition completely cured.
• the term "curing” refers to the hardening of a mixture of epoxide-functionalised compounds and hardener by chemical cross-linking, brought about by chemical additives, ultraviolet radiation, electron beam, microwave, infrared radiation, or heat.
• the resin viscosity drops initially upon the application of heat, passes through a region of maximum flow, and begins to increase as the chemical reactions increase the average length and the degree of cross-linking between the constituent resins. This process continues until a continuous 3-dimensional network of polymer chains is created - this stage is termed gelation.
• vitrification is the development of the glassy state of a compound or composition (such as the thermoset crosslinked resin composition) as the curing reaction increases and the glass transition temperature (Tg) reaches the curing temperature (Tcure). It means that the vitrification occurs when the Tg and the Tcure are equal.
• the glass transition temperature (Tg) value has to be understood as the temperature at which the mechanical properties of the resin radically changed due to the internal movement of the polymer chains that form the resin.
• DSC Differential Scanning Calorimetry
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising: (a) mixing a mixture of two difunctional epoxy resins comprising a bisphenol epoxy resin, with a cross-linking agent of formula (II) as defined above, in a molar ratio from 2:1 to 1 :1, and a catalyst as defined above; and
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is a mixture of epoxide- functionalised resins comprising one or more tetrafunctional resins.
• thermoset crosslinked epoxy resin composition is obtainable by a method wherein in step (I) the epoxide-functionalised resin with a functionality equal to or higher than 2 is the tetrafunctional epoxy resin tetraglycidyl methylene dianiline.
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising: (a) mixing a mixture of two difunctional epoxy resins, one of them being a bisphenol epoxy resin, and a tetrafunctional epoxy resin, with a cross-linking agent of formula (II) as defined above, in a molar ratio from 2:1 to 1 :1, and a catalyst as defined above; and
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising: (a) mixing a mixture comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether; 1 ,4-butanediol diglycidyl ether; and a tetrafunctional epoxy resin, with a cross-linking agent of formula (III) or formula (IV) or a mixture thereof as defined above, in a molar ratio from 2:1 to 1 :1, and a catalyst as defined above; and
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising: (a) mixing a mixture of two difunctional epoxy resins, one of them being a bisphenol epoxy resin at from 20% to 80% by weight, and tetraglycidyl methylene dianiline, with a cross-linking agent of formula (II) as defined above, in a molar ratio from 2:1 to 1 :1, and a catalyst as defined above; and (b) curing the reaction mixture at a temperature from 10 °C to 200 °C.
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising: (a) mixing a mixture comprising bisphenol A diglycidyl ether or bisphenol F diglycidyl ether; neopentyl glycol diglycidyl ether; and tetraglycidyl methylene dianiline, with a cross-linking agent of formula (III) or formula (IV) or a mixture thereof as defined above, in a molar ratio from 2:1 to 1 :1, and a catalyst as defined above; and
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition is obtainable by a method comprising:
• thermoset crosslinked epoxy resin composition of the first aspect of the present invention which comprises:
• Ar-S-S-Ar (I) at a molar ratio between the epoxide groups of the epoxy-functionalised resin and the epoxide-reactive functional moieties of the cross-linking agent of formula (I) from the stoichiometric to a two-fold excess of epoxide reactive functional group;
• step (II) curing the mixture obtained in step (I) at a temperature from 10°C to 200°C for a period of time such that the thermoset crosslinked epoxide resin reaches a glass transition temperature value which is equal to or higher than 10°C but equal to or lower than the maximum glass transition temperature.
• thermoset crosslinked epoxy resin composition characterized by its preparation process of the first aspect of the present invention, also apply herein to the preparation process of the thermoset crosslinked epoxy resin.
• thermoset composite comprising:
• composite refers to a material made from two or more constituent materials with significantly different physical or chemical properties, that when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure.
• Composite materials are generally used for buildings, bridges, wind blades, aircraft and automotive structural components, boat hulls, storage tanks, among others.
• thermoset composite of the present invention comprises:
• thermoset crosslinked epoxide resin composition as defined in the first aspect of the invention, being the sum of being the sum of volumes of (a) and (b) equal to 100%.
• thermoset composite of the present invention comprises:
• thermoset crosslinked epoxide resin composition of the present invention (b) a matrix phase comprising from 50-100% by weight with respect to the total weight of the matrix phase of the thermoset crosslinked epoxide resin composition of the present invention.
• volume percentage (%) when referred to the reinforcement and matrix phases, is estimated dividing the volume of the phase with respect to the total volume of the composite and the resulting value is multiplied by 100.
• the fibre volume of a composite material may be determined by chemical matrix digestion (ASTM D3171) or resin burn-off (ASTM D2584), in which the matrix is eliminated and the fibres weighed and calculated from substituent weights and densities.
• a photomicrographic technique may be used in which the number of fibres in a given area of a polished cross section is counted and the volume fraction determined as the area fraction of each constituent.
• thermoset composite of the present invention is a multilayer composite.
• the thermoset composite of the present invention is a multi-layered composite comprising two or more layers comprising each one of the layers: a) a reinforcement phase comprising fibres, and (b) a matrix phase comprising the thermoset crosslinked epoxide resin as defined in the present invention.
• the thermoset composite of the present invention is a multi-layered composite comprising two or more layers as defined above, wherein each layer is a prepreg as defined in the present invention.
• the term "reinforcement phase comprising fibres” is a material that comprise one or more fibre layers in a discontinuous or continuous way.
• the term “fibres” encompasses woven, non-crimped, non-woven, unidirectional UD, and multi-axial textile structure form.
• Illustrative examples of woven fibre forms include plain, satin or twill weave style.
• Illustrative examples of non-crimped and multi-axial fibre forms include a number of plies and fibre orientations. Such styles and forms are well known in the composite reinforcement field and are commercially available from a number of companies.
• the composite is one wherein the (a) reinforcement phase comprises fibres selected from the group consisting of organic fibres and inorganic fibres. In one embodiment, the composite is one wherein the (a) reinforcement phase comprises fibres selected from the group consisting of glass, carbon, aramide (made of aromatic polyamides), flax, and combination thereof. In one embodiment, the composite is one wherein the (a) reinforcement phase comprises glass fibre. In one embodiment, the composite is one wherein the (a) reinforcement phase consists of glass fibre. In one embodiment, the composite is one wherein the (a) reinforcement phase comprises carbon fibre. In one embodiment, the composite is one wherein the (a) reinforcement phase consists of carbon fibre.
• the composite of the second aspect of the invention, and particularly the matrix phase of the composite further comprises one or more additional excipients or carriers.
• additional excipients or carriers include, among others, polymers different from the thermoset crosslinked epoxy resin composition of the first aspect of the invention, pigments, dyes, fillers, plasticizers, flame retardants, antioxidants, lubricants, metals, and mixtures thereof.
• Illustrative non-limitative examples of polymers include, among others, elastomers, thermoplastics, thermoplastic elastomers, impact additives, and combinations thereof.
• pigments means coloured particles that are insoluble in the thermoset crosslinked epoxy resin composition of the first aspect of the invention.
• pigments that may be used in the invention, mention may be made of titanium oxide, carbon black, carbon nanotubes, metal particles, silica, metal oxides, metal sulphides or any other mineral pigment; mention may also be made of phthalocyanines, anthraquinones, quinacridones, dioxazines, azo pigments or any other organic pigment, natural pigments (madder, indigo, crimson, cochineal, etc.) and mixtures of pigments.
• the pigments may represent from 0.05% to 15% by weight relative to the weight of the material.
• dye means molecules that are soluble in the thermoset crosslinked epoxy resin composition of the first aspect of the invention and that have the capacity of absorbing part of the visible radiation.
• thermoset crosslinked epoxy resin composition of the invention mention may be made of: trihydrate alumina, silica, clays, calcium carbonate, carbon black, kaolin, and whiskers.
• the composite of the present invention has a recycling rate of the thermoset crosslinked epoxy resin composition of the first aspect of the invention equal to or higher than 70% w/w. In an embodiment, the composite of the present invention has a recycling rate of the thermoset crosslinked epoxy resin composition of the first aspect of the invention equal to or higher than 75% w/w. In an embodiment, the composite of the present invention has a recycling rate of the thermoset crosslinked epoxy resin composition of the first aspect of the invention equal to or higher than 80% w/w. In an embodiment, the composite of the present invention has a recycling rate of the thermoset crosslinked epoxy resin composition of the first aspect of the invention equal to or higher than 85% w/w.
• the composite of the present invention has a recycling rate of the thermoset crosslinked epoxy resin composition of the first aspect of the invention equal to or higher than 90% w/w. In an embodiment, the composite of the present invention has a recycling rate of the thermoset crosslinked epoxy resin composition of the first aspect of the invention equal to or higher than 95% w/w.
• the composite of the present invention has a recycling rate of the reinforcement phase comprising fibres equal to or higher than 95% w/w. In an embodiment, the composite of the present invention has a recycling rate of the reinforcement phase comprising fibres equal to or higher than 96% w/w. In an embodiment, the composite of the present invention has a recycling rate of reinforcement phase comprising fibres equal to or higher than 97% w/w. In an embodiment, the composite of the present invention has a recycling rate of the reinforcement phase comprising fibres equal to or higher than 98% w/w. In an embodiment, the composite of the present invention has a recycling rate of the reinforcement phase comprising fibres equal to or higher than 99% w/w. In an embodiment, the composite of the present invention has a recycling rate of the reinforcement phase comprising fibres of about 100% w/w.
• the composite of the present invention has a recycling rate of the thermoset crosslinked epoxy resin composition of the first aspect of the invention equal to or higher than 70% w/w; particularly equal to or higher than 75% w/w; particularly equal to or higher than 80% w/w; particularly equal to or higher than 85% w/w; particularly equal to or higher than 90% w/w; particularly about 95% w/w; and a recycling rate of the reinforcement phase comprising fibres equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w.
• the composite of the present invention has a recycling rate of the thermoset crosslinked epoxy resin composition of the first aspect of the invention is about 95% w/w; and a recycling rate of the reinforcement phase comprising fibres of about 100% w/w.
• the composite of the present invention is one that when submitted to the recycling process of the present invention then the recycled thermoset crosslinked epoxy resin composition of the first aspect of the invention has a chemical purity equal to or higher than 95% w/w; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w.
• the composite of the present invention is one that when submitted to the recycling process of the present invention then the recycled reinforcement phase comprising fibres has a chemical purity equal to or higher than 95% w/w; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w.
• the composite of the present invention is one that when submitted to the recycling process of the present invention then the recycled thermoset crosslinked epoxy resin composition of the first aspect of the invention has a chemical purity equal to or higher than 95% w/w; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w; and the recycled reinforcement phase comprising fibres has a chemical purity equal to or higher than 95% w/w; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w.
• the composite of the present invention is one that when submitted to the recycling process of the present invention then the recycled thermoset crosslinked epoxy resin composition of the first aspect of the invention has a chemical purity equal to or higher than 95% w/w; and the recycled reinforcement phase comprising fibres has a chemical purity equal to or higher than 95% w/w.
• the composite of the present invention is one that when submitted to the recycling process of the present invention then the recycled thermoset crosslinked epoxy resin composition of the first aspect of the invention has a chemical purity equal to or higher than 95% w/w; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w; and the composite of the present invention has a recycling rate of the reinforcement phase comprising fibres equal to or higher than 95% w/w; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; and particularly about 100% w/w.
• the composite of the present invention is one that when submitted to the recycling process of the present invention then the recycled reinforcement phase comprising fibres has a chemical purity equal to or higher than 95%; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w; and a recycling rate of the reinforcement phase comprising fibres equal to or higher than 96% w/w; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w.
• the composite of the present invention is one that when submitted to the recycling process of the present invention then the recycled reinforcement phase comprising fibres has a chemical purity is about 100% w/w; and a recycling rate of the reinforcement phase comprising fibres of about 100% w/w.
• the composite of the present invention is one that when submitted to the recycling process of the present invention then the recycled thermoset crosslinked epoxy resin composition of the first aspect of the invention has a chemical purity equal to or higher than 95% w/w; particularly equal to or higher than 96% w/w; particularly equal to or higher than 97% w/w; particularly equal to or higher than 98% w/w; particularly equal to or higher than 99% w/w; particularly about 100% w/w; and the composite of the present invention has a recycling rate of the recycled thermoset crosslinked epoxy resin composition equal to or higher than 70% w/w; particularly equal to or higher than 75% w/w; particularly equal to or higher than 80% w/w; particularly equal to or higher than 85% w/w; particularly equal to or higher than 90% w/w; and particularly about 95% w/w; and when submitted to the recycling process of the present invention then the recycled reinforcement phase comprising fibres has a chemical purity equal to or higher than 95% w/w; particularly equal to or higher than 9
• the "recycling rate” refers to the dry weight of the recycled component (i.e. the recycled thermoset crosslinked epoxy resin composition or the recycled reinforcement phase comprising fibres) with respect to the dry weight of the component used as starting material ((i.e. the thermoset crosslinked epoxy resin composition or the reinforcement phase comprising fibres) for the preparation of the composite, and the resulting value is multiplied by 100.
• the "chemical purity” refers to the measurement of the amount of impurities found in a chemical sample.
• the chemical purity of the recycled thermoset crosslinked epoxy resin composition is measured as the weight of thermoset crosslinked epoxy resin with respect to the total weight of the recycled thermoset crosslinked epoxy resin (which may contain variable amounts of reinforcement phase comprising fibres) and the resulting value is multiplied by 100.
• the chemical purity of the recycled reinforcement phase comprising fibres is measured as the weight of reinforcement phase comprising fibres with respect to the total weight of recycled reinforcement phase comprising fibres (which may contain a variable amount of crosslinked epoxy resin composition) and the resulting value is multiplied by 100.
• the chemical purity can be measured by any appropriate method known in the state of the art. In the present invention, the chemical purity is measured by thermogravimetric analysis (TGA) or by Fourier transform infrared spectroscopy (FTIR).
• Sheet Moulding Compound is an integrated ready-to-mould composition of fibres, resin, and filler.
• SMC is made by metering a resin paste onto a thin plastic carrier film. The compound is made by chopping continuous fibres onto the resin paste as it is conveyed on the film. This fibre/resin mix is further covered by another layer of resin on a second carrier film. Compaction rollers knead the fibres into the resin for uniform fibre distribution and wetting. The compound sandwiched between the carrier films is gathered into rolls and stored until it matures. Upon maturation, SMC is tack free and has a leather-like consistency. The carrier film is removed and the sheet is prepared into a charge of predetermined weight and shape. The charge is placed on the bottom of two mould halves in a compression press and it cures under specific heat and pressure conditions.
• the vacuum bag technique involves the placing and sealing of a flexible bag over a composite lay-up and evacuating all the air from under the bag. The removal of air forces the bag down onto the lay-up with a consolidation pressure of up to 1 atmosphere (1 bar). The completed assembly, with vacuum still applied, is placed inside an oven or on a heated mould with good air circulation, and the composite is produced after a relatively short cure cycle.
• the autoclave technique requires a similar vacuum bag but the oven is replaced by an autoclave.
• the autoclave is a pressure vessel which provides the curing conditions for the composite where the application of vacuum, pressure, heat up rate and cure temperature are controlled.
• Compression moulding describes the process whereby a stack of prepregs is compressed between a set matched dies using a powerful press, and then cured while under compression.
• the moulds may be heated or the prepregs may be preheated and formed in relatively cool moulds.
• a diaphragm forming autoclave technique can be used.
• Diaphragm forming is an autoclave technique used solely for thermoplastic matrix composites. The laminate is laid up flat between two diaphragms (superplastic aluminium sheets or high temperature polymeric films), the diaphragms are clamped in a frame (the laminate is not clamped), then the laminate is formed using heat, vacuum, and pressure in the autoclave.
• the prepreg is a "partially (pre)-impregnated” prepreg.
• the term “partially (pre)- impregnated” means a prepreg wherein the reinforcement material layer is (pre)-impregnated with the thermoset crosslinked epoxide resin of the invention from one side.
• the prepreg is a "totally (pre)-impregnated” prepreg.
• the term “totally (pre)-impregnated” means that both sides of the reinforcement material layer are (pre)-impregnated with the thermoset crosslinked epoxide resin of the invention.
• the prepreg is one which comprises a thermoset crosslinked epoxide resin composition partially cured of the invention, partially or totally (pre)-impregnated.
• thermoset crosslinked epoxide resin composition partially cured is one obtainable by a method as defined herein above and below, wherein the curing step (ii) is performed at a temperature from 10°C to 200 °C for a period of time such that the resin reaches at least 25% of the maximum Tg value.
• the prepreg is one which comprises a thermoset crosslinked epoxide resin composition completely cured of the invention, partially or totally (pre)-impregnated.
• thermoset crosslinked epoxide resin composition completely cured is one obtainable by a method as defined herein above and below, wherein the curing step (ii) is performed at a temperature from 10°C to 200 °C for a period of time such that the resin reaches at maximum Tg value.
• prepreg comprising a thermoset crosslinked epoxide resin completely cured of the invention and "enduring prepreg” have the same meaning and are used interchangeable.
• the term “enduring prepreg” means that the prepreg has no time limitation between the manufacturing date and the processing date of the prepreg.
• the use of the "prepreg” of the present invention, and particularly the "enduring prepregs” of the present invention for the manufacture of the composites of the second aspect of the invention can be performed under different conditions depending on the nature of the prepreg and the type of composite intended to be obtained. There are well-known standard technologies in the state of the art for the manufacture of composites from prepregs as disclosed herein above (see method 8).
• the manufacturing of the composites of the present invention starting from one or more partially cured prepregs of the present invention comprises curing an moulding the prepreg simultaneously into the desired shape of the composite. In one embodiment, the manufacturing of the composites of the present invention starting from one or more enduring prepregs of the present invention comprises applying the appropriate temperature and pressure to allow the moulding into the desired shape.
• the epoxide-functionalised resin with a functionality equal to or higher than 2 is coated onto a paper substrate in a thin film.
• the reinforcement (unidirectional fibres or fabric) and the thin film obtained in the first stage are then brought together on the prepreg machine. Impregnation of the thin film obtained in the first stage into the fibre is achieved using heat and pressure from nip rollers.
• the final prepreg is then wound onto a core.
• the solvent dip method can only be used to produce fabric prepregs. In this technique, the mixture of the first stage is dissolved in a bath of solvent and reinforcing fabric is dipped into. The solvent is evaporated from the prepreg in a drying oven. This can be horizontal or vertical.
• the fourth aspect of the present invention relates to an article comprising the thermoset crosslinked epoxy resin.
• the article comprises one or more thermoset composite of the present invention comprising the thermoset crosslinked epoxy resin.
• the article comprises one or more prepregs of the present invention comprising the thermoset crosslinked epoxy resin.
• thermoset crosslinked epoxide resin particularly to the epoxide-functionalised resin, the cross-linking agent, the catalyst, and the reaction conditions of the preparation process); the composite (particularly the reinforcement phase comprising fibres, and the matrix phase), and the prepreg, also apply herein for the article of the fourth aspect of the invention.
• the articles of the present invention are useful in a wide range of technical fields, such as for example the automotive, the aerospace, the railway, the sports and goods, and the renewable energy sectors, among others.
• the fifth aspect of the invention is a process for recycling the thermoset crosslinked epoxy resin composition of the present invention as well as the reinforcement phase comprising fibres from a composite, or from a prepreg, or from an article comprising the thermoset crosslinked epoxy resin composition of the present invention.
• a composite, or prepreg, or article comprising the thermoset crosslinked epoxy resin composition of the present invention is easily recyclable under mild conditions without alteration of the physical and chemical properties of both the thermoset crosslinked epoxy resin composition and the reinforcement phase. Fact that allows its re-used and/or repurposed without hindering the quality/properties of the composites/articles containing the recycled thermoset crosslinked epoxy resin composition.
• the recycling process comprises immersing the composite, or the prepreg, or the article comprising the thermoset crosslinked epoxy resin composition of the present invention in a solvent or mixture of solvents having a boiling temperature above the glass transition temperature of the thermoset crosslinked epoxy resin composition and a Hansen solubility parameter (Ra) equal to or lower than 7.5.
• the Hansen solubility parameter (Ra) is commonly measured by equation (1):
• Ra 2 4(5DI-5D 2 ) 2 + (5PI-5P 2 ) 2 + (5HI-5H 2 ) 2 (eq. 1)
• thermoset crosslinked epoxy resin composition for dispersion expressed in MPa 1/2
• thermoset crosslinked epoxy resin composition for polars expressed in MPa 1/2
• thermoset crosslinked epoxy resin composition for hydrogen-bonding expressed in MPa 1/2
• the recycling process of the invention is performed in the absence of a base or an acid.
• suitable solvents or mixtures of solvents include, but not limited to, dimethylformamide, dimethyl sulfoxide, N-Methyl-2-pyrrolidone, gamma-Valero lactone, benzyl alcohol, methoxybenzene, cyclopentanone, cyclohexanone, N-buty l-pyrrolone, a mixture of dimethyl sulfoxide: acetone (40:60), a mixture of Dimethylformamide and methyl ethyl ketone (63:37).
• the recycling process of the invention further comprises a separation step of the thermoset crosslinked epoxy resin of the invention and the reinforcement phase comprising fibres after the immersing step consisting of removing the reinforcement phase comprising fibres from the solvent media.
• the recycling process of the invention further comprises a recovery step after the separation step.
• the recycling process of the invention further comprises a recovery step of the thermoset crosslinked epoxy resin composition after the separation step comprising removing the solvent by any of the suitable techniques known to a person skilled and known in the art (such as evaporation, centrifugation, among others).
• the recycling process of the invention further comprises a recovery step of the reinforcement after the separation step comprising drying the reinforcement. This step is commonly performed in an oven under vacuum conditions.
• thermoset crosslinked epoxide resin of the present invention It is also part of the invention a prepreg and article comprising the recyclable thermoset crosslinked epoxide resin of the present invention, which when submitted to the recycling process conditions of the process of the present invention; then, the recycling rate of the thermoset crosslinked epoxide resin, and reinforcement; as well as the chemical purity of recycled thermoset crosslinked epoxide resin, and reinforcement are those mentioned herein above for the composite of the present invention.
• Epoxy resin D.E.R 332 was purchased from Sigma-Aldrich, hardeners Diethyltoluenediamine (DETDA) and 4- bis(amino phenyl) disulphide (4-AFD) were purchased from Biosynth Carbosynth and glass fibre reinforcement (HexForce 1103 PLAIN, basis weight 290 g/m2) was purchased from Hexcel.
• D.E.R 332 (10 g), AFD (4.6 g) and the catalyst (150 mg) were fed into a 50 mL flask. The mixture was heated at 80 °C until the AFD was completely dissolved in the resin, while degassing by magnetic stirring under vacuum. Then, the mixture was poured onto a 2 mm thick mould and was allowed to cure at 130 °C for 60 minutes.
• the catalyst used in each Example is disclosed herein below:
• Comparative Example 3 was obtained following the process for the preparation of Example 1 (cf. section 2.1 .) BUT in the absence of a catalyst, falling outside the scope of the present invention.
• a release film was placed onto the part and then a layer of breather cloth was placed to soak up excess resin and ensure an adequate path for the vacuum pressure.
• the part was sealed with a vacuum bagging film and a hose connected to a vacuum pump was attached to the sealed part. Vacuum was then applied to the enclosed part which was compacted by the vacuum. Once air was evacuated, curing was carried out in an oven at 130 °C for 60 minutes.
• Comparative multilayer composites (comparative Examples 4, 5and 6) were obtained following the general preparation process for composites disclosed in section 3.1 BUT changing the thermoset crosslinked epoxy resin composition of the present invention by the comparative thermoset crosslinked epoxy resin compositions 1, 2 or 3, respectively.
• the tested composites were immersed in sodium hydroxide 1N, hydrochloric acid 1 N, tetrahydrofuran (THF), toluene and acetone separately at room temperature. After 72 hours at that temperature all samples remained unaltered.
• thermoset crosslinked epoxy resin compositions and the fibre reinforcement from the multilayer epoxy composites of the present invention (Examples 5-8) and comparative multilayer epoxy composites (comparative Examples 4-6) were performed in different solvents.
• thermoset crosslinked epoxy resins Further, the Tg of the thermoset crosslinked epoxy resins and the cleanliness level of the fibres thus separated were determined.
• Tg represents the Tg value of the thermoset crosslinked epoxy resin composition in powder form obtained after submitting the multilayer epoxy composite to the general separation (recovery) process
• the multilayer epoxy composites comprising a thermoset crosslinked epoxy resin composition of the present invention obtainable by a method that comprises mixing an epoxide-functionalised resin with a cross-linking agent and a catalyst; and curing the mixture thus obtained, with the proviso that the cross-linking agent comprises a disulphide bond are recyclable in the presence of solvents under mild conditions without the use of additional chemical agents (such as acid or bases).
• the recycling step is only performed by the use of a solvent or a mixture of solvents having a boiling temperature above the Tg of the composite to be recycled and a Hansen solubility parameter (abbreviated as HSP but commonly called Ra) below 7.5.
• HSP Hansen solubility parameter
• thermoset crosslinked epoxy resin composition of the present invention show the ability of being recyclable under mild conditions.
• both the thermoset crosslinked epoxy resin composition and the fibrous reinforcement can be separated at the end of its life and recovered maintaining its original properties, allowing its directly re-sold, re-used, or repurposed without hindering the quality/properties of the recycled composites/articles containing it.
• thermoset epoxy resin composition of the present invention also has a mechanochromic behaviour, which mean that when the thermoset crosslinked epoxy resin composition or a composite containing it receives an impact, a color change in the visible region of the EM spectrum is observed on the damaged area.
• mechanochromic behaviour is reversible and disappears in a few hours. This property confers to the composite of the invention a great value because it permits detecting damage by simple visual inspection.

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• 2023
  • 2023-07-04 EP EP23738015.9A patent/EP4551636A1/de not_active Withdrawn
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