The present invention relates to an epoxy resin composition useful as thermoset for paint, coatings or adhesives comprising a polyepoxide derived from poly(limonene carbonate), a polymer derived from biomass (free from bisphenol A and aromatic groups), and a polyamine hardener. It also relates to a polyepoxide compound useful in said composition.

BACKGROUND ART

Thermosets are three-dimensional cross-linked polymeric materials obtained by curing or hardening of a soft solid or a liquid or a viscous prepolymer resin. Such curing typically takes place using a source of heat, a source of radiation and/or a catalyst. The curing process creates extensive cross-linking between polymer chains of the components of the curable composition and produces materials that cannot be dissolved or melted. Thermosets have thus found numerous industrial applications, such as coatings, circuit components, composite materials, adhesives and packaging. Epoxy resins are typical examples of widely used thermosets because they exhibit excellent properties, such as high hardness, superior chemical and oil resistances, water and corrosion resistance as well as good insulating properties. Most commercially available epoxy formulations currently derive from bisphenol A diglycidyl ether, also called BADGE or DGEBA, that is obtained from non-renewable fossil resources and is currently being banned in certain countries for safety reasons. There is consequently a need for sustainable alternatives to fossil-based epoxy components originating for instance from biomass in order to respond to crude oil shortage and replace hazardous materials.

In this regard, Savonnet and Cramail reported in 2018 some biobased epoxy monomers based on di-, tri- or tetradiglycidyl ethers of divanillyl alcohol, which can be obtained from bio-based vanillin. When used in combination with cyclo-aliphatic diamine such as IPDA (isophorone diamine), these epoxy components produce crosslinked materials at a temperature of about 50 ^e C and having a glass transition temperature higher than 138 ^e C. The authors further report that the produced cross-linked materials exhibit similar thermomechanical properties than epoxy networks resulting from the cross-linking of DGEBA with IPDA. Also, the profile of thermal degradation of the cross-linked materials formed from vanillyl alcohol derivatives is comparable to the one of epoxy networks resulting from the cross-linking of DGEBA with IPDA. Polyglycidyl ethers of divanillyl alcohol are thus presented as suitable alternatives to DGEBA in epoxy components. The authors are however silent about the fact that the preparation of synthetic vanillin is more cost effective than the extraction of vanillin from biological sources. Other epoxies derived from bio-sourced components are known in the art. For instance, epoxies deriving from soybean oil, isosorbide, eugenol, catechin, rosin or resveratrol have been reported. In most cases, epichlorohydrin is used in the preparation of the epoxy component comprising the oxirane reactive moieties (glycidyl ethers). Epichlorohydrin is a known carcinogen, mutagen and reprotoxic product.

Limonene is a terpene compound extractable from the peel of citrus fruits and is thus available in large amounts from the food industry. Limonene is currently mainly used as a flavouring ingredient and/or fragrance for cosmetics and detergents. A molecule of limonene comprises two unsaturated double bonds, which has led scientists to develop new components based on limonene for epoxy-based thermosets, by taking advantage of the reactivity of these double bonds. For instance, Xu and co-workers reported a diepoxy compound derived from the electrophilic aromatic substitution of 1 -napthol with limonene, and whereby the hydroxyl groups of the naphthol are further reacted with epichlorhydrin to produce a diepoxy compound, whereby the fragment deriving from limonene acts as a spacing cycloaliphatic group. The prepared epoxy component proved less reactive than DGEBA towards curing. Nevertheless, the resulting polymers exhibited high glass transition temperatures (higher than 171 ^e C), thanks to the presence of rigid aromatic naphthalene rings in the epoxy component. Such component is not fully derivable from biomass.

In another approach, Couture and co-workers reported a bis-limonene oxide compound prepared from limonene. The employed synthesis does not require the use of epichlorhydrin to introduce the reactive oxirane group. Instead, authors have reported a bis-limonene oxide prepared by thiol-ene condensation of 2,2'-oxybis(ethane-1 -thiol) with two molecules of limonene oxide. The prepared epoxy component was formulated in a curable resin together with anhydride compounds such as HMPA (hexahydro-4-methylphthalic anhydride) and initiator catalysts such as 2-ethyl-methyl-imidazole (EMI). After curing 4 h at 180 ^e C, the obtained solid material exhibits a glass transition temperature of 75 ^e C. Thermal resistance of the bis-limonene oxide formulation was compared with a similar DGEBA based formulation. It was found that the DGEBA based thermoset was more resistant to heat, which is attributed to the presence of aromatic rings in the cured material. According to the authors, anhydrides provide epoxy thermosets with lower toxicity and higher glass transition temperature than thermosets formed from polyamines. However, the authors do not disclose a curable composition comprising the reported bis-limonene oxide and an oil-based polyamine hardener. Mattar and co-workers also reported the use of limonene in the preparation of a bio-based diamine useful as hardener in epoxy resin compositions based on diglycidyl ether derivative of resorcinol. The disclosed diamine is prepared by thiol-ene reaction of limonene with 2-amino- ethane-1 -thiol. The resulting thermoset was obtained after heating of the resin. It was found that the resin prepared from limonene-based diamine exhibits an improved behaviour in terms of fracture toughness and stiffness if compared with a similar thermoset resulting from curing of resorcinol-based epoxy with HMPA.

Limonene has also been used in the art as a starting material in the preparation of polymers, such as polyesters and polycarbonates. In particular, the preparation of poly(limonene)carbonate (PLC) by co-polymerization of limonene oxide with carbon dioxide has been reported by Hauenstein and co-workers. PLC is a fully bio-based thermoplastic polymer comprising in its molecular formula an additional double bond that can be used to introduce functional groups. The pendent double bond in the repeating unit of PLC has been used to introduce functional features to the polymer, thereby producing either a rubber, an antibacterial polymer, pH dependent water solubility or hydrophilicity. This functionality was introduced by the means of thiol-ene reactivity.

Li et al. used oligomeric PLC (molecular weight of about 2.8-6 kDa) as component for a thermoset based on thiol-ene chemistry in combination with multifunctional thiols, including bio-based polythiols deriving from soybean oil. The prepared compositions were cured at 160 ^e C, temperature at which thiol-ene crosslinking was optimal. The resulting thiol-ene networks exhibit glass transition temperatures higher than 100 ^e C and are transparent materials resistant to acetone, thus being suitable for coating applications. The authors are however silent about the use of PLC derivatives in amine-based epoxy resins for thermoset applications.

US Patent application number US2019/0322803 discloses the preparation of poly(limonene) carbonate oxide (PLCO). PLCO is a polymer having as repeating unit a fragment of formula (I)

This application further discloses the use of PLCO as a starting material for the formation of a cyclic carbonate from the pendent oxirane group by reaction of PLCO with carbon dioxide. The resulting poly(limonene)dicarbonate exhibits high glass transition temperature of up to 180 ^e C. The use of PLCO as epoxy in an epoxy resin composition, be it in combination with an amine hardener or an anhydride hardener, is however not disclosed.

From what is known in the art, it derives that there is still a need for providing sustainable heat curable compositions comprising epoxy components deriving from biomass, in particular from limonene, and amine hardeners.

SUMMARY OF THE INVENTION

The inventors after extensive and exhaustive research have developed a curable composition comprising a polyepoxide having as repeating unit at least an epoxide derived from limonene and an amine hardener. In particular, the inventors found that PLCO and polyepoxides deriving from PLCO, are useful as polyepoxides in the formulation of epoxy thermoset resins comprising polyamine hardeners. The inventors unexpectedly found that when PLCO and/or polyepoxides deriving from PLCO are combined with at least one polyamine hardener having an Amine Hydrogen Equivalent Weight (AHEW) within a range of 50 to 600 grams per equivalent, the resulting composition is curable and produces materials with suitable mechanical properties. It is advantageous because the produced thermoset materials are not brittle, thereby being suitable for a broad range of applications such as paints, coatings, stoving enamels and adhesives. The inventors have found in particular that when the amine hardener has a AHEW value that is below 50 or above 600 grams per equivalent, the cured material resulting from the curable composition is brittle. It is unexpected as no disclosure in the art teaches or discloses a curable composition comprising an amine hardener combined with a polyepoxide that is PLCO or derives from PLCO.

Thus, in a first aspect, the invention relates to a curable composition comprising:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II)

(I) (ID wherein, in the moiety of formula (II), the dashed bond represents the presence or absence of a covalent bond,

Ri represents a diradical selected from the group consisting of oxy, thioxy, carbonyloxy, oxycarbonyl and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl, (Ci-Ce)haloalkyl, (Ci-Ce)alkyloxy, (Ci-Ce)alkylcarbonyloxy and (Ci- Ce)alkyloxycarbonyl; when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen, (Ci-Ce)alkyl, (Ci-Ce)haloalkyl, (C1- Ce)alkyloxy, (Ci-Ce)alkylcarbonyloxy and (Ci-Ce)alkyloxycarbonyl; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, thioxy, carbonyloxy, oxycarbonyl and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl, (C1- Ce)haloalkyl, (Ci-Ce)alkyloxy, (Ci-Ce)alkylcarbonyloxy and (Ci-Ce)alkyloxycarbonyl; each of R3 and R4 independently represents a radical selected from the group consisting of hydrogen, (Ci-Ce)alkyl, (Ci-Ce)haloalkyl, (Ci-Ce)alkyloxy, (Ci-Ce)alkylcarbonyloxy and (Ci -Ce)alkyloxycarbonyl ; and wherein the number of repeating units of formula (I) comprised in the polyepoxide is larger than the number of moieties of formula (II); and

(ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups and having an amine hydrogen equivalent weight (AHEW) of between 50 and 600 grams per equivalent. Inventors have thus found that a polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) is useful as curable polyepoxide in an epoxy thermoset formulation; in particular when the polyepoxide resin is combined with a amine hardener.

In a second aspect, the invention thus relates to a use as defined in claim 24.

The inventors also found that the compositions of the first aspect can be useful as a paint or as an adhesive. In a third and a fourth aspect, the invention thus relates to uses of some compositions of the first aspect as defined in claims 25 and 26.

A fifth aspect of the invention relates to a cured composition obtained by heating the composition of the first aspect of the invention.

A sixth aspect of the invention relates to a polyepoxide having as repeating unit a moiety of formula (I) and having one or more further repeating units of formula (II), as defined in the first aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the heat flow as a function of temperature as measured by Differential Scanning Calorimetry (DSC) for different epoxy resin compositions according to the invention: (i) PLCOJeff 1 :1 before curing; (ii) PLCO:Jeff 1 :1 post-curing; (iii) PLCO:Jeff 1 :2 before curing; (iv) PLCOJeff 1 :2 post-curing; (v) PLCO:Cray 1 :1 before curing; (vi) PLCO:Cray 1 :1 postcuring; (vii) PLCO:Cray 2:1 before curing; (viii) PLCO:Cray 1 :1 post-curing; being “Jeff’ polyoxypropylenediamine (Huntsman International LLC, Jeffamine® D-400, AHEW 115 g/eq, average molecular weight 430 g/mol, CAS number 9046-10-0, hereinafter referred to as “Jeff”) and “Cray” Crayamid® 195X60 (Arkema Coatings Resins, AHEW 240 g/eq, CAS number 1380300-09-3, hereinafter referred to as “Cray”).

Figure 2 -top shows the DSC curve - enthalpy release during a period of time (y axis) as a function of temperature (x axis) - of a composition comprising PLCDE as defined in Preparative Example 2 and Jeffamine in a 1 :1 epoxide to amine ratio combined with 2% accelerator in weight (see example 3-2) cured by stoving (curve (a)) or at room temperature (curve (b)). Figure 2-bottom shows the thermogravimetric analysis expressed as a percentage of weight loss in function of temperature of the cured composition of Example 3-2 (curve (d)) and its derivative (curve (c)).

DETAILED DESCRIPTION OF THE INVENTION

All terms as used herein in this application, unless otherwise stated, shall be understood in their ordinary meaning as known in the state of the art. Other more specific definitions for certain terms as used in the present application are as set forth below and are intended to apply uniformly throughout the specification and claims, unless an otherwise expressly set out definition provides a broader definition.

For the purposes of the present invention, any ranges given include both the lower and the upper end-points of the range. Ranges given, such as temperatures, times, molar ratio and the like, should be considered approximate (this is, with a 5% margin of variation around indicated point), unless specifically stated otherwise.

In the context of the present invention, the term “AHEW” stands for Amine Hydrogen Equivalent Weight and is a parameter known in the art that reflects the reactivity of an amine hardener and is calculated as the ratio of the molecular weight, expressed in gram per mole, of the amine hardener to the number of hydrogen atoms comprised in a molecule of hardener and that are directly connected to a nitrogen atom comprised in an amine group of the molecular formula of the hardener.

In the context of the present invention, the term “EEW” stands for Epoxy Equivalent Weight and is a parameter known in the art that reflects the reactivity of a polyepoxide and is calculated as the ratio of the molecular weight, expressed in gram per mole, of the polyepoxide to the number of oxygen atoms comprised in an oxirane fragment of the molecule of polyepoxide. Thus, DGEBA, which has a molecular weight of 340 grams and two epoxy groups, would have an epoxy equivalent weight of 170 grams per equivalent.

In the context of the present invention, the term “polyepoxide” refers to a compound having in its molecular formula a plurality of oxirane molecular fragments, having the general formula whereby the wavy lines represent possible connection points with the remainder of the molecule.

In the context of the present invention, the term “oxy” refers to a diradical of formula -O-. Similarly, the term “thioxy” refers to a diradical of formula -S-.

In the context of the present invention, the term “carbonyloxy” refers to a diradical of formula -(CO)O-, being -(CO)- a carbonyl diradical. Similarly, the term “oxycarbonyl” refers to a diradical of formula -O(CO)-, being -(CO)- a carbonyl diradical.

In the context of the invention, the term “halo” or “halogen” or their plurals refer to a halogen radical or group, they thus refer to fluoro, chloro, bromo or iodo.

In the context of the present invention, the term “alkyl” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims. Examples of alkyl groups include, but are not limited to: methyl, ethyl, propyl, iso-propyl, butyl, iso-butyl, tert-butyl, pentyl, and hexyl. The term “branched alkyl” and its plural refer to a saturated hydrocarbon group having the number of carbon atoms indicated in the description or in the claims wherein at least one of the carbon atoms is tertiary or quaternary. Examples of branched alkyl groups include, but are not limited to, iso-propyl, iso-butyl, tert-butyl, isobutyl, neo-pentyl, 2-methylpentyl and 2-methylhexyl.

In the context of the present invention, the term “alkyloxy” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims which is attached to the remainder of the formula through an ether group (-O-).

In the context of the present invention, the term “alkyloxycarbonyl” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims, which is attached to the remainder of the formula through an oxycarbonyl group (that is, a group of formula G-OCO- where G is the saturated linear or branched hydrocarbon group).

In the context of the present invention, the term “alkylcarbonyloxy” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims, which is attached to the remainder of the formula through a carbonyloxy group (that is, a group of formula G-COO- where G is the saturated linear or branched hydrocarbon group).

In the context of the present invention, the term “polyamidoamine” and its plural refer to a compound comprising in its molecular formula one or more amine groups which are attached to a polyamide backbone.

In the context of the present invention, the term “polyoxoalkyleneamine” and its plural refer to a compound comprising in its molecular formula one or more amine groups which are attached to a polyoxyalkylene backbone.

In the context of the present invention, the term “mannich-type diamines or triamines” refers to a compound comprising in its molecular formula 2 or 3 amino groups having at their beta position (i.e. at a distance of two atoms) a keto group.

In the context of the present invention, the term “polyepoxide of the novolak type” and its plural refer to a polyepoxide compound comprising in its molecular formula the repeating unit of formula:

According to the first aspect of the invention, the curable composition comprises (i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) as defined above and (ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups and having an amine hydrogen equivalent weight (AHEW) of between 50 and 600 grams per equivalent.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described below, in the moiety of formula (II), at least one of R3 and R4 is hydrogen. Preferably, both R ₃ and R4 represent hydrogen.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), R1 is a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-C6)alkyloxy.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), R1 is a diradical deriving from a radical selected from methyl, ethyl and methoxy.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (C1- Ce)alkyl; preferably it is hydrogen.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (Ci-Ce)alkyl group.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), when the dashed bond represents the presence of a covalent bond, R2 represents a diradical deriving from a methyl or ethyl group.

Thus, in a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), when the dashed bond represents the absence of a covalent bond; then R ₂ is hydrogen; or, alternatively, when the dashed bond represents the presence of a covalent bond; then R ₂ is a diradical deriving from a (Ci-Ce)alkyl group.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), at least one of R3 and R4 is hydrogen, and, when the dashed bond represents the absence of a covalent bond, R ₂ represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R ₂ represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R ₂ is a diradical deriving from a (Ci-Ce)alkyl group.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), R1 is a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy, at least one of R3 and R4 is hydrogen, and, when the dashed bond represents the absence of a covalent bond, R ₂ represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R ₂ represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (C1- Ce)alkyloxy; preferably, R ₂ is a diradical deriving from a (Ci-Ce)alkyl group.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, in the moiety of formula (II), R1 is a diradical deriving from a radical selected from the group consisting of methyl, ethyl and methoxy; R ₃ and R4 are both hydrogen; and, when the dashed bond represents the absence of a covalent bond, R ₂ represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (Ci-Ce)alkyl group such as methyl or ethyl.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the moiety of formula (II) is selected from the group consisting of the moieties of formula (Ila) and (lib);

(Ha) (lib)

The moiety of formula (Ila) is a moiety of formula (II) wherein R1 is a diradical deriving from an ethyl group; the dashed bond represents the presence of a single bond; R2 is a diradical deriving from a methyl group; both R ₃ and R4 are hydrogen. The moiety of formula (lib) is a moiety of formula (II) wherein R1 is a diradical deriving from methoxy group; the dashed bond represents the absence of a covalent bond; R2 is hydrogen; both R ₃ and R4 are hydrogen.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a polyepoxide having a molecular weight of between 500 and 20000 grams per mole.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a polyepoxide having a molecular weight of between 1000 and 15000 grams per mole.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a polyepoxide having a molecular weight of between 5000 and 12000 grams per mole. When the polyepoxide is one having as further optional repeating unit the moiety of formula (Ila), it is advantageous as there is no need to carry out the previous step of de-polymerizing the polymer, as disclosed in the art by Li and co-workers.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a polyepoxide as described above wherein the number of repeating units of formula (I) comprised in the polyepoxide is between 5 to 30 times the number of moieties of formula (II); preferably the number of moieties of formula (I) is between 5 to 15 times the number of moieties of formula (II); more preferably, the number of moieties of formula (I) is about 10 times the number of moieties of formula (II).

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a polyepoxide as described above and having an EEW value of between 200 and 300 grams per equivalent.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a polyepoxide having as repeating unit the moiety of formula (la) as defined above and having preferably an average molecular weight of about 9000 grams per mole.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a polyepoxide having as repeating units the moieties of formula (la) and (II) wherein the number of moieties of formula (la) is about 10 times the number of moieties of formula (II), said polyepoxide having an average molecular weight of about 5500 grams per mole.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a polyepoxide having as repeating units the moieties of formula (la) and (Ila) wherein the number of moieties of formula (la) is about 10 times the number of moieties of formula (Ila), said polyepoxide preferably having an average molecular weight of about 5500 grams per mole.

As defined above, the curable composition of the first aspect of the invention further comprises a hardener comprising in its molecular formula a plurality of amine groups and having an amine hydrogen equivalent weight (AHEW) of between 50 and 600 grams per equivalent. Such amine hardeners are known in the art and well known to the skilled person, such as those disclosed in Coatings Formulation, 2nd. Edition, Bodo Muller & Ulrich Poth, Editorial Vincentz Network, 2011 , inserted herein by reference.

The selection of a specific range of AHEW values for the amine hardeners advantageously allows for producing films upon curing. Inventors found in particular that, when using hardeners having AHEW values outside this range, brittle and fragile materials were produced. The selection of amine hardeners with specific AHEW values thus allows producing stabled cured materials.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a hardener comprising in its molecular formula a plurality of amine groups and having an amine hydrogen equivalent weight (AHEW) of between 50 and 600 grams per equivalent that is selected from the group consisting of polyamidoamines, polyoxoalkylene amines, aliphatic, cycloaliphatic and aromatic compounds comprising in their molecular formula a plurality of primary amine groups.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a hardener comprising in its molecular formula a plurality of amine groups and having an amine hydrogen equivalent weight (AHEW) of between 60 and 550 grams per equivalent.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a hardener that is selected from the group consisting of diamines or triamines of a polyether backbone having an AHEW comprised from 115 to 514 grams per equivalent, said polyether backbone being selected from the group consisting of polyethylene oxide) (EO), polypropylene oxide) (PO), polypropylene glycol (PPG) and co-polymers thereof; aliphatic and cycloaliphatic polyamines, having an AHEW comprised from 100 to 150 grams per equivalent, Mannich-type diamines or triamines having an AHEW comprised from 50 to 115 grams per equivalent, diamines of a polyethylene glycol (PEG) backbone having an AHEW comprised from 132 to 250 grams per equivalent; diamines or triamines of a copolymer of poly(tetramethylene ether glycol) (PTMEG) with polypropylene glycol (PPG) having an AHEW of about 260 grams per equivalent; diamines or triamines of a PTMEG backbone having an AHEW of about 260 grams per equivalent; polyetheramines having an AHEW of about 67 grams per equivalent; polyamidoamines having an AHEW comprised from 130 to 280 grams per equivalent; and polyamide adducts, having an AHEW comprised from 140 to 280 grams per equivalent.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a hardener that is selected from the group consisting of diamines or triamines of a polyether backbone having an AHEW comprised from 1 15 to 514 grams per equivalent, said polyether backbone being selected from the group consisting of polyethylene oxide) (PEG), polypropylene oxide) (PPG), polypropylene glycol (PPG) and co-polymers thereof; diamines of a polyethylene glycol (PEG) backbone having an AHEW comprised from 132 to 250 grams per equivalent; diamines or triamines of a copolymer of poly(tetramethylene ether glycol (PTMEG) with polypropylene glycol (PPG) having an AHEW of about 260 grams per equivalent; diamines or triamines of a PTMEG backbone having an AHEW of about 260 grams per equivalent; polyetheramines having an AHEW of about 67 grams per equivalent; polyamidoamines having an AHEW comprised from 130 to 280 grams per equivalent; and polyamide adducts, having an AHEW comprised from 140 to 280 grams per equivalent.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a hardener that is selected from the group consisting of diamines or triamines of a polyether backbone having an AHEW comprised from 1 15 to 514 grams per equivalent, said polyether backbone being selected from the group consisting of polyethylene oxide) (PEG), polypropylene oxide) (PPG), polypropylene glycol (PPG) and co-polymers thereof; and polyamidoamines having an AHEW comprised from 130 to 280 grams per equivalent.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a hardener that is selected from the group consisting of diamines or triamines of a polyether backbone having an AHEW comprised from 320 to 480 grams per equivalent, said polyether backbone being selected from the group consisting of polyethylene oxide) (PEO), polypropylene oxide) (PPO), polypropylene glycol (PPG) and co-polymers thereof; and polyamidoamines having an AHEW comprised from 130 to 280 grams per equivalent.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises a hardener that is selected from the group consisting of polyoxypropylene diamine having a molecular weight of between 320 and 480 g per mole, and a polyamidoamine that is preferably the compound having as CAS registry number 1380300-09-3. The compound having as CAS registry number 1380300- 09-3 has an AHEW value of between 240 to 270 grams per equivalent.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) wherein, in the moiety of formula (II), Ri is a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy, at least one of R3 and R4 is hydrogen, and, when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (Ci-Ce)alkyl group; and

(ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups that is selected from the group consisting of diamines or triamines of a polyether backbone having an AHEW comprised from 1 15 to 514 grams per equivalent, said polyether backbone being selected from the group consisting of polyethylene oxide) (PEO), polypropylene oxide) (PPO), polypropylene glycol (PPG) and co-polymers thereof; diamines of a polyethylene glycol (PEG) backbone having an AHEW comprised from 132 to 250 grams per equivalent; diamines or triamines of a copolymer of poly(tetramethylene ether glycol (PTMEG) with polypropylene glycol (PPG) having an AHEW of about 260 grams per equivalent; diamines or triamines of a PTMEG backbone having an AHEW of about 260 grams per equivalent; polyetheramines having an AHEW of about 67 grams per equivalent; polyamidoamines having an AHEW comprised from 130 to 280 grams per equivalent; and polyamide adducts, having an AHEW comprised from 140 to 280 grams per equivalent.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) wherein, in the moiety of formula (II), Ri is a diradical deriving from a radical selected from the group consisting of methyl, ethyl and methoxy; R ₃ and R4 are both hydrogen; and, when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (C1- Ce)alkyl group such as methyl or ethyl, and

(ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups that is selected from the group consisting of diamines or triamines of a polyether backbone having an AHEW comprised from 1 15 to 514 grams per equivalent, said polyether backbone being selected from the group consisting of polyethylene oxide) (PEG), polypropylene oxide) (PPO), polypropylene glycol (PPG) and co-polymers thereof; diamines of a polyethylene glycol (PEG) backbone having an AHEW comprised from 132 to 250 grams per equivalent; diamines or triamines of a copolymer of poly(tetramethylene ether glycol (PTMEG) with polypropylene glycol (PPG) having an AHEW of about 260 grams per equivalent; diamines or triamines of a PTMEG backbone having an AHEW of about 260 grams per equivalent; polyetheramines having an AHEW of about 67 grams per equivalent; polyamidoamines having an AHEW comprised from 130 to 280 grams per equivalent; and polyamide adducts, having an AHEW comprised from 140 to 280 grams per equivalent.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) wherein, in the moiety of formula (II), R1 is a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Celalkyloxy, at least one of R3 and R4 is hydrogen, and, when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (Ci-Ce)alkyl group; and

(ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups that is selected from the group consisting of polyoxypropylene diamine having a molecular weight of between 320 and 480 g per mole, and a polyamidoamine that is preferably the compound having as CAS registry number 1380300-09-3.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) wherein, in the moiety of formula (II), R1 is a diradical deriving from a radical selected from the group consisting of methyl, ethyl and methoxy; R ₃ and R4 are both hydrogen; and, when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (C1- Ce)alkyl group such as methyl or ethyl, and

(ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups that is selected from the group consisting of polyoxypropylene diamine having a molecular weight of between 320 and 480 g per mole, and a polyamidoamine that is preferably the compound having as CAS registry number 1380300-09-3.

In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition is one wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the at least one hardener is from 1 :2 to 2:1. More particularly, the molar ratio of epoxy groups in the polyepoxide to amine groups in the at least one hardener is 1 :1 . In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) wherein, in the moiety of formula (II), Ri is a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy, at least one of R3 and R4 is hydrogen, and, when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (Ci-Ce)alkyl group; and (ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups that is selected from the group consisting of diamines or triamines of a polyether backbone having an AHEW comprised from 115 to 514 grams per equivalent, said polyether backbone being selected from the group consisting of polyethylene oxide) (PEO), polypropylene oxide) (PPO), polypropylene glycol (PPG) and copolymers thereof; diamines of a polyethylene glycol (PEG) backbone having an AHEW comprised from 132 to 250 grams per equivalent; diamines or triamines of a copolymer of poly(tetramethylene ether glycol (PTMEG) with polypropylene glycol (PPG) having an AHEW of about 260 grams per equivalent; diamines or triamines of a PTMEG backbone having an AHEW of about 260 grams per equivalent; polyetheramines having an AHEW of about 67 grams per equivalent; polyamidoamines having an AHEW comprised from 130 to 280 grams per equivalent; and polyamide adducts, having an AHEW comprised from 140 to 280 grams per equivalent; and wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the at least one hardener is 1 :1 .

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) wherein, in the moiety of formula (II), R1 is a diradical deriving from a radical selected from the group consisting of methyl, ethyl and methoxy; R ₃ and R4 are both hydrogen; and, when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (C1- Ce)alkyl group such as methyl or ethyl, and

(ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups that is selected from the group consisting of diamines or triamines of a polyether backbone having an AHEW comprised from 1 15 to 514 grams per equivalent, said polyether backbone being selected from the group consisting of polyethylene oxide) (PEO), polypropylene oxide) (PPO), polypropylene glycol (PPG) and co-polymers thereof; diamines of a polyethylene glycol (PEG) backbone having an AHEW comprised from 132 to 250 grams per equivalent; diamines or triamines of a copolymer of poly(tetramethylene ether glycol (PTMEG) with polypropylene glycol (PPG) having an AHEW of about 260 grams per equivalent; diamines or triamines of a PTMEG backbone having an AHEW of about 260 grams per equivalent; polyetheramines having an AHEW of about 67 grams per equivalent; polyamidoamines having an AHEW comprised from 130 to 280 grams per equivalent; and polyamide adducts, having an AHEW comprised from 140 to 280 grams per equivalent; and wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the at least one hardener is 1 :1 .

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) wherein, in the moiety of formula (II), R1 is a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy, at least one of R3 and R4 is hydrogen, and, when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (Ci-Ce)alkyl group; and (ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups that is selected from the group consisting of polyoxypropylene diamine having a molecular weight of between 320 and 480 g per mole, and a polyamidoamine that is preferably the compound having as CAS registry number 1380300-09-3; and wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the at least one hardener is 1 :1 .

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition comprises:

(i) at least one polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) wherein, in the moiety of formula (II), Ri is a diradical deriving from a radical selected from the group consisting of methyl, ethyl and methoxy; R ₃ and R4 are both hydrogen; and, when the dashed bond represents the absence of a covalent bond, R2 represents a radical selected from the group consisting of hydrogen or (Ci-Ce)alkyl; preferably it is hydrogen; or, alternatively; when the dashed bond represents the presence of a covalent bond, R2 represents a diradical selected from the group consisting of oxy, carbonyloxy and a diradical deriving from a radical selected from the group consisting of (Ci-Ce)alkyl and (Ci-Ce)alkyloxy; preferably, R2 is a diradical deriving from a (C1- Ce)alkyl group such as methyl or ethyl, and

(ii) at least one hardener comprising in its molecular formula a plurality of primary amine groups that is selected from the group consisting of polyoxypropylene diamine having a molecular weight of between 320 and 480 g per mole, and a polyamidoamine that is preferably the compound having as CAS registry number 1380300-09-3; and wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the at least one hardener is 1 :1 .

In particular embodiments of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a non-halogenated solvent.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a non-halogenated solvent selected from the group consisting of tetrahydrofuran (THF), ketones, esters, xylene, toluene, aliphatic or aromatic hydrocarbons and glycol ethers. Suitable ketones are for instance acetone or methyl ethyl ketone (MEK). A suitable ester is for instance ethyl acetate.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a non-halogenated solvent is selected from the group consisting of tetrahydrofuran (THF), methyl ethyl ketone (MEK), xylene, toluene, aliphatic or aromatic hydrocarbons and glycol ethers; and is preferably selected from xylene, methyl ethyl ketone (MEK) and a mixture thereof.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises xylene as nonhalogenated solvent.

In an even more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a non-halogenated solvent that is selected and is in such an amount that it satisfies the requirements of the Directive 2004/42/CE of the European Parliament and of the Council of European Union (inserted herein by reference). Such a composition advantageously contains a low amount of volatile organic components (also referred to herein as VOC), and is thus less harmful to health and environment.

In another more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a non-halogenated solvent in an amount of 2 millilitres per gram of the polyepoxide.

In another more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a non-halogenated solvent selected from the group consisting of tetrahydrofuran (THE), methyl ethyl ketone (MEK), xylene, toluene, aliphatic or aromatic hydrocarbons and glycol ethers; and is preferably selected from xylene, methyl ethyl ketone (MEK) and a mixture thereof and is used in an amount of 2 millilitres per gram of the polyepoxide.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a levelling agent. Suitable levelling agents are known in the art and will become apparent to the skilled in the art person. Those include, among others, benzyl alcohol, silicone-based agents such as polydimethylsiloxane (PDMS), acrylate-based agents such as polyacrylates, fluorocarbon-based agents, and hydrocarbon-based levelling agents. Preferably, the levelling agent is benzyl alcohol. Also preferably, the levelling agent is used in an amount of 0.5 to 3 % in weight of the composition.

In a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a catalyst for opening the oxirane groups in the moieties of formula (I) and (II). Suitable catalysts for opening the oxirane groups in the moieties of formula (I) and (II) are known in the art and will become apparent to the skilled in the art person. Those include, among others, nonyl phenol and its isomers, [2,4,6- tris(dimethylaminomethyl)phenol], benzyl dimethylamine and triethanolamine. Preferably, the catalyst for opening the oxirane groups in the moieties of formula (I) and (II) is [2,4,6- tris(dimethylaminomethyl)phenol]. Also preferably, the composition comprises the catalyst for opening the oxirane groups in the moieties of formula (I) and (II) in an amount of between 0.1 % and 3% by weight of the polyepoxide resin.

It is also contemplated that the composition of the first aspect of the invention further comprises one or more additional polyepoxide compounds. Suitable additional polyepoxide compounds for curable compositions are known in the art and will become apparent to the skilled person. Such compounds include those disclosed in Coatings Formulation, 2nd. Edition, Bodo Muller & Ulrich Poth, Editorial Vincentz Network, 201 1 , inserted herein by reference. Consequently, it is contemplated that the polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) is used as a replacement of known polyepoxide compounds in known curable compositions of polyepoxide compounds with amine hardeners. This is advantageous as the environmental footprint of the resulting composition is reduced because the polyepoxide having as repeating unit a moiety of formula (I) and, optionally, one or more further repeating units of formula (II) incorporates carbon dioxide molecules (carbon dioxide is a gas with strong greenhouse effect) as well as biomass-derived building blocks, deriving from limonene, in the moiety of formula (I).

Thus, in a particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises an additional polyepoxide selected from the group consisting of polyepoxides comprising at least two glycidyl moieties in their molecular formula, cycloaliphatic epoxides and epoxidized vegetable oils. Polyepoxides having at least two glycidyl moieties comprised in their molecular formula are known in the art and include, among others, polyepoxides derived from bis-phenol A such as bisphenol A diglycidyl ether (DGEBA), polyepoxides of the novolak type, aliphatic glycidyl epoxy resins and aliphatic glycidyl epoxy amines.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises an additional polyepoxide comprising at least two glycidyl moieties in its molecular formula.

In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises an additional polyepoxide selected from the group consisting of polyepoxides derived from bisphenol A such as bisphenol A diglycidyl ether (DGEBA), polyepoxides of the novolak type, cycloaliphatic epoxides, epoxidized vegetable oils, aliphatic glycidyl epoxy resins and aliphatic glycidyl epoxy amines.

In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises an additional polyepoxide selected from the group consisting of polyepoxides derived from bis-phenol A such as bisphenol A diglycidyl ether (DGEBA), polyepoxides of the novolak type, epoxidized vegetable oils and aliphatic glycidyl epoxy resins.

In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises an additional polyepoxide that is DGEBA.

The additional polyepoxide comprised in the composition according to the first aspect of the invention may in particular have an epoxy equivalent weight value of between 100 and 4000 grams of epoxy per equivalent. More particularly, it may have an epoxy equivalent weight value of between 120 and 300 grams of epoxy per equivalent. For instance, DGEBA has an EEW value of about 190 grams of epoxy per equivalent.

In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises an additional polyepoxide as defined above and the weight ratio of the polyepoxide comprising the repeating unit of formula (I) and, optionally, one or more further repeating units of formula (II) to the additional polyepoxide is comprised from 1 :20 to 1 :1.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises an additional polyepoxide as defined above and the weight ratio of the polyepoxide comprising the repeating unit of formula

(I) and, optionally, one or more further repeating units of formula (II) to the additional polyepoxide is from 1 :1 to 1 :4; preferably, the weight ratio of the polyepoxide comprising the repeating unit of formula (I) and, optionally, one or more further repeating units of formula (II) to the additional polyepoxide is 1 :1 or 1 :4. A weight ratio of 1 :4 of the polyepoxide comprising the repeating unit of formula (I) and, optionally, one or more further repeating units of formula

(II) to the additional polyepoxide corresponds to a situation where the polyepoxide comprising the repeating unit of formula (I) and, optionally, one or more further repeating units of formula (II) is in the presence of one gram per each fours grams of the additional polyepoxide. A weight ratio of 1 :1 of the polyepoxide comprising the repeating unit of formula (I) and, optionally, one or more further repeating units of formula (II) to the additional polyepoxide corresponds to a situation where the polyepoxide comprising the repeating unit of formula (I) and, optionally, one or more further repeating units of formula (II) is in the presence of one gram per each gram of the additional polyepoxide.

In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition is one wherein the polyepoxide has as repeating unit a moiety of formula (I) and one or more further repeating units of formula (II) as defined in any one of the embodiments described above. Such a composition is advantageous because, when the polyepoxide of the curable composition comprises one or more repeating units of formula (II), it allows a faster curing of the composition in an unexpected manner. Without being bound to theory, it is believed that the reduced curing time is associated to the reactivity of the oxirane functional groups in the polyepoxide with nucleophiles, such as amine groups of hardener components. In particular, it is believed that the oxirane moiety comprised in the repeating unit of formula (II) - which is based on a tertiary and a secondary carbon atom - is more reactive towards nucleophilic opening than the oxirane moiety comprised in the repeating unit of formula (I) - which is based on a quaternary and a secondary carbon atom. In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a pigment. Pigments suitable for curable epoxy compositions are well known in the art and will become apparent to the skilled person. Suitable pigments include, among others, titanium dioxide, carbon black, phthalocyanines, iron oxides, aluminum and zinc flakes, and pearlescent pigments.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a pigment that is titanium dioxide. Curable compositions comprising a pigment may be useful as coating or as a paint.

When the curable composition of the first aspect of the invention comprises a pigment, said pigment may be present in an amount of from 0.1% to 10% in weight. Preferably, when the curable composition of the first aspect of the invention comprises a pigment, said pigment may be present in an amount of from 2% to 5% in weight.

In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a filler. Fillers suitable for curable epoxy compositions are well known in the art and will become apparent to the skilled person. Suitable fillers include, among others, silica, silicates such as talc, quartz, kaolin, mica or wollastonite, carbonate salts and sulphate salts.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a filler that is silica nanoparticles.

When the curable composition of the first aspect of the invention comprises a filler, said filler may in particular be present in an amount of from 10% to 70% in weight. Preferably, when the curable composition of the first aspect of the invention comprises a filler, said filler may be present in an amount of from 10% to 50% in weight.

In another particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises an additive selected from the group consisting of defoamers, wetting agents, dispersing agents, anti-aging agents, antimicrobial agents, anti-corrosion agents, plasticizers, lubricants, fire or flame retardants. The composition according to any one of claims 1 to 22 further comprising an additive selected from the group consisting of defoamers, wetting agents, dispersing agents, anti-aging agents, anti-microbial agents, anti-corrosion agents, plasticizers, lubricants, fire or flame retardants. Such additives are well-known in the art and will become apparent to the skilled person.

In a more particular embodiment of the first aspect of the invention, optionally in combination with one or more of the preferred embodiments of the first aspect of the invention described above and below, the curable composition further comprises a defoamer. Defoamer compounds are known in the art and suitable defoamers will become apparent to the skilled in the art person. These include for instance, BYK A500 (CAS 1 12938-56-4), BYK 525 (CAS 155808-19-8), BYK 066N (CAS 871694-48-3), BYK W966 (CAS 223251 -74-9) and BYK 530 (CAS 63148-53-8.) More particularly, said defoamer is the compound having as CAS number 63148-53-8 (commercial name: BYK A530). When the curable composition of the first aspect of the invention comprises a defoamer, said defoamer may in particular be present in an amount of from 0.1% to 5% in weight. Preferably, when the curable composition of the first aspect of the invention comprises a defoamer, said defoamer may be present in an amount of from 1% to 2% in weight.

When the curable composition of the first aspect of the invention comprises a wetting agent, said wetting agent may in particular be present in an amount of from 0.1% to 5% in weight. Similarly, when the curable composition of the first aspect of the invention comprises a dispersing agent, said dispersing agent may in particular be present in an amount of from 0.1% to 5% in weight. Similarly, when the curable composition of the first aspect of the invention comprises an anti-aging agent, said anti-aging agent may in particular be present in an amount of from 0.1 % to 5% in weight. Similarly, when the curable composition of the first aspect of the invention comprises an anti-microbial agent, said anti-microbial agent may in particular be present in an amount of from 0.1% to 5% in weight. Similarly, when the curable composition of the first aspect of the invention comprises an anti-corrosion agent, said anti-corrosion agent may in particular be present in an amount of from 10 % to 80% in weight. Similarly, when the curable composition of the first aspect of the invention comprises a plasticizer, said plasticizer may in particular be present in an amount of from 0.1% to 5% in weight. Similarly, when the curable composition of the first aspect of the invention comprises a lubricant, said lubricant agent may in particular be present in an amount of from 0.1% to 5% in weight. Similarly, when the curable composition of the first aspect of the invention comprises a fire or flame retardant, said fire or flame retardant may in particular be present in an amount of from 2% to 5% in weight.

In another particular embodiment of the first aspect of the invention, the curable composition consists of a polyepoxide having as repeating unit a moiety of formula (I) as defined above and polyoxypropylenediamine (Huntsman International LLC, Jeffamine® D-400, AHEW 1 15 g/eq, average molecular weight 430 g/mol, CAS number 9046-10-0, hereinafter referred to as “Jeff”) as hardener, wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the hardener is 1 :1 or 1 :2. Said curable composition may further optionally comprise a catalyst consisting of Accelerator® 960-1 (CAS number 90-72-2) in an amount of from 1 to 3% in weight of the total amount by weight of the polyepoxide resin, preferably 2% in weight.

In another particular embodiment of the first aspect of the invention, the curable composition consists of a polyepoxide having as repeating unit a moiety of formula (I) as defined above and Crayamid® 195X60 (Arkema Coatings Resins, AHEW 240 g/eq, CAS number 1380300- 09-3, hereinafter referred to as “Cray”) as hardener, wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the hardener is 1 :1 or 2:1 . Said curable composition may further optionally comprise a catalyst consisting of Accelerator® 960-1 (CAS number 90-72- 2) in an amount of from 1 to 3% in weight of the total amount by weight of the polyepoxide resin, preferably 2% in weight.

In another particular embodiment of the first aspect of the invention, the curable composition consists of a polyepoxide having in its molecular formula a repeating unit a moiety of formula (I) and a further repeating unit of formula (Ila) as defined above, whereby the number of repeating units of formula (I) is about 10 times the number of moieties of formula (Ila) and polyoxypropylenediamine (Jeffamine® D-400, AHEW 1 15 g/eq, average molecular weight 430 g/mol, CAS number 9046-10-0, hereinafter referred to as “Jeff”) as hardener, wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the hardener is 1 :1. Said composition may further optionally comprise a catalyst consisting of Accelerator® 960-1 (CAS number 90-72-2) in an amount of from 1 to 3% in weight of the total amount by weight of the polyepoxide resin, preferably 2% in weight.

In another particular embodiment of the first aspect of the invention, the curable composition consists of:

- a component A consisting of a mixture of a polyepoxide having in its molecular formula a repeating unit a moiety of formula (I) and a further repeating unit of formula (Ila) as defined above, whereby the number of repeating units of formula (I) is about 10 times the number of moieties of formula (Ila) with DGEBA, such that the weight ratio of the polyepoxide to DGEBA is 1 :1 or 1 :4;

- and a component B that is polyoxypropylenediamine (Jeffamine® D-400, AHEW 1 15 g/eq, average molecular weight 430 g/mol, CAS number 9046-10-0, hereinafter referred to as “Jeff”) as hardener, wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the hardener is 1 :1 . Said composition may further optionally comprise a catalyst consisting of Accelerator® 960-1 (CAS number 90-72-2) in an amount of from 1 to 3% in weight of the total amount by weight of component A, preferably 2% in weight.

In another particular embodiment of the first aspect of the invention, the curable composition is a bi-component paint composition consisting of: (i) a component A consisting of:

- a polyepoxide having in its molecular formula a repeating unit a moiety of formula (I), that is PLCO, in an amount of 8,46% by weight,

- a polyepoxide comprising at least two glycidyl moieties in its molecular formula that is DGEBA and is present in an amount of 33,82% by weight,

- a pigment, that is titanium dioxide, in an amount of 5,01 % by weight,

- a filler, that is silica nanoparticles, in an amount of 48,67%,

- an additive, that is the defoamer agent having as CAS number 63148-53-8, in an amount of 2,02% by weight,

- benzyl alcohol, as a solvent, in an amount of 2,02% by weight, and

(ii) a component B consisting of polyoxypropylenediamine (Jeffamine® D-400, AHEW 115 g/eq, average molecular weight: 430 g/mol, herein referred to as “Jeff”), as an amine hardener, in an amount of 14,75 grams per each 100 grams of component A.

Such a composition is useful as two epoxy components paint formulation and advantageously presents a reduced environmental footprint than the corresponding formulation comprising DGEBA as sole epoxide.

As defined above, a second aspect of the invention relates to the use of a polyepoxide compound having a plurality of repeating units of formula (I) and, optionally, one or more further repeating units of formula (II) as defined above as curable polyepoxide in an epoxy resin formulation.

In a more particular embodiment of the second aspect of the invention, the polyepoxide compound comprises one or more further repeating units of formula (II) as defined above. More particularly, Ri, R ₂ , R3, R4, and the dashed bond of the moiety of formula (II) are as defined in any one of the single and combined particular embodiments of the first aspect of the invention defined above for these parameters. As mentioned above, such polyepoxide is advantageous because it allows reducing the curing time of the curable composition, which is attributed to a higher reactivity of the polyepoxide towards nucleophilic attack by the amine groups of the hardener.

As defined above, a third aspect of the invention refers to the use of the composition of the first aspect of the invention as adhesive. The compositions of the first aspect of the invention whereby the polyepoxide compound comprises one or more further repeating units of formula (II) as defined above are particularly useful for adhesive applications. In such compositions, Ri, R ₂ , R3, R4, and the dashed bond of the moiety of formula (II) are as defined in any one of the single and combined particular embodiments of the first aspect of the invention defined above for these parameters. Such compositions may also further comprise a catalyst for accelerating the curing of the composition, such as Accelerator® 960-1 .

The third aspect of the invention thus relates in a particular embodiment to the use as adhesive of the composition consisting of:

- a component A consisting of a polyepoxide having in its molecular formula a repeating unit a moiety of formula (I) and a further repeating unit of formula (Ila) as defined above, whereby the number of repeating units of formula (I) is about 10 times the number of moieties of formula (Ha);

- and a component B that is polyoxypropylenediamine (Jeffamine® D-400, AHEW 1 15 g/eq, average molecular weight 430 g/mol, CAS number 9046-10-0, hereinafter referred to as “Jeff”) as hardener, wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the hardener is 1 :1 ,

- optionally a catalyst consisting of Accelerator® 960-1 (CAS number 90-72-2) in an amount of 2% in weight of the total amount by weight of the polyepoxide.

The third aspect of the invention thus relates in a particular embodiment to the use as adhesive of the composition consisting of:

- a component A consisting of a mixture of a polyepoxide having in its molecular formula a repeating unit a moiety of formula (I) and a further repeating unit of formula (Ila) as defined above, whereby the number of repeating units of formula (I) is about 10 times the number of moieties of formula (Ila), with DGEBA, such that the weight ratio of the polyepoxide to DGEBA is 1 :1 or 1 :4;

- and a component B that is polyoxypropylenediamine (Jeffamine® D-400, AHEW 1 15 g/eq, average molecular weight 430 g/mol, CAS number 9046-10-0, hereinafter referred to as “Jeff”) as hardener, wherein the molar ratio of epoxy groups in the polyepoxide to amine groups in the hardener is 1 :1 ,

- optionally a catalyst consisting of Accelerator® 960-1 (CAS number 90-72-2) in an amount of 2% in weight of the total amount by weight of the polyepoxide.

As defined above, a fourth aspect of the invention refers to the use of the composition of the first aspect of the invention as paint. The compositions of the first aspect of the invention comprising one or more component selected from the group consisting of a pigment, a filler, an additive, a catalyst and a mixture thereof, said components being as defined above in any particular embodiment of the first aspect of the invention, are particularly useful as paint formulations. More particularly, the compositions of the first aspect of the invention comprising at least a pigment and a filler are useful as paint formulations, said components being as defined above in any particular embodiment of the first aspect of the invention.

The fourth aspect of the invention thus relates in a particular embodiment to the use as paint of the composition consisting of:

(i) a component A consisting of:

- a polyepoxide having in its molecular formula a repeating unit a moiety of formula (I), that is PLCO, in an amount of 8,46% by weight,

- a polyepoxide comprising at least two glycidyl moieties in its molecular formula that is DGEBA and is present in an amount of 33,82% by weight,

- a pigment, that is titanium dioxide, in an amount of 5,01% by weight,

- a filler, that is silica nanoparticles, in an amount of 48,67%,

- an additive, that is the defoamer agent having as CAS number 63148-53-8, in an amount of 2,02% by weight,

- benzyl alcohol, as a solvent, in an amount of 2,02% by weight, and

(ii) a component B consisting of polyoxypropylenediamine (Jeffamine® D-400, AHEW 115 g/eq, average molecular weight: 430 g/mol, herein referred to as “Jeff”), as an amine hardener, in an amount of 14,75 grams per each 100 grams of component A.

The invention also relates in a fifth aspect to a cured composition obtained by heating the composition according to any one of the particular and preferred embodiments of the first aspect of the invention. Such heating step may in particular be carried out at a temperature ranging from 10 ^e C to 200 ^e C. It was found that increasing the temperature allows accelerating the curing of the composition.

In a particular embodiment, the fifth aspect of the invention relates to the cured composition obtained by heating the compositions described in any embodiment of the third or fourth aspect of the invention. The cured composition obtained by heating a composition as described in the third aspect of the invention is suitable for adhesive applications. The cured composition obtained by heating a composition as described in the fourth aspect of the invention is suitable for paint applications.

In other embodiments, the fifth aspect of the invention relates to a cured composition suitable for stoving enamels. Such cured composition may be obtained by heating a composition comprising two epoxy components, as defined above.

In other embodiments, the fifth aspect of the invention relates to a cured composition suitable for heat resistant stoving adhesives.

In more particular embodiments of the fourth and fifth aspects of the invention, when the curable composition comprises a catalyst consisting of Accelerator® 960-1 (CAS number 90- 72-2), the heating step leading to the formation of the cured composition may advantageously be carried out at a temperature of between 10 ^e C and 35 ^e C, preferably at room temperature. This is particularly useful when the composition is used as a coating, a paint or an adhesive, as there is no need to further heat the composition above room temperature for it to cure.

In more particular embodiments of the fourth and fifth aspects of the invention, the cured composition has a glass transition temperature comprised between 10 ^e C and 100 ^e C.

In other more particular embodiments of the fourth and fifth aspects of the invention, the cured composition has a Young modulus of between 300 and 800 MPa, maximum tensile strength of between 10 and 50 MPa, and an elongation at break of between 1 and 50 %, as measured by the tensile strength of industrial standard UNE-EN-ISO 527:2020.

In other more particular embodiments of the fifth aspect of the invention, the cured composition has an adhesive force of between 2 and 10 MPa, as measured by pull-off test UNE-EN- ISO4624:2016. Such compositions are particularly advantageous as adhesive compositions.

In a sixth aspect, as defined above, the invention relates to a polyepoxide having as repeating unit a moiety of formula (I) and having one or more further repeating units of formula (II), said polyepoxide being as defined in any one of the particular and preferred embodiments described above. In particular, the polyepoxide compound of the sixth aspect of the invention is one wherein, in the repeating units of formula (II), Ri, R2, R3, R4, and the dashed bond of the moiety of formula (II) are as defined in any one of the single and combined particular embodiments of the first aspect of the invention defined above for these parameters. Such polyepoxide compounds are advantageous because they provide a faster curing, attributed to the presence of the moieties of formula (II) in the molecular formula of the epoxide. Without being bound to theory, it is believed that the oxirane functional group in the moiety of formula (II) is more reactive towards nucleophilic attacks, e.g. by amine groups of hardeners, than the oxirane functional group in the moiety of formula (I) because the oxirane moiety comprised in the repeating unit of formula (II) is based on a tertiary and a secondary carbon atom while the oxirane moiety comprised in the repeating unit of formula (I) is based on a quaternary and a secondary carbon atom.

Thus, in preferred embodiments, the sixth aspect of the invention relates to a polyepoxide having as repeating unit a moiety of formula (I) and having one or more further repeating units of formula (II), wherein the moiety of formula (II) is selected from the group consisting of the moieties of formula (Ila) and (lib)

(Ha) (Hb)

Throughout the description and claims the word “comprises" and variations of the word, are not intended to exclude other technical features, additives, components or steps. Furthermore, the word “comprise” encompasses the case of “consisting of”. Additional objects, advantages and features of the present invention will become apparent to those skilled in the art upon examination of the description or may be learned by practice of the present invention. The following examples are provided by way of illustration, and they are not intended to be limiting of the present invention. Furthermore, the present invention covers all possible combinations of particular and preferred embodiments described herein.

The research leading to this invention has received funding from “la Caixa” Foundation under the grant agreement LCF/PR/PR20/51150010 and from Ministerio de Ciencia e Innovacion (MICINN) and Fondo Europeo de Desarrollo Regional (FEDER): “A way to make Europe” (grant number RTI2018-098951 -B-I00). EXAMPLES

General considerations

All water-sensitive operations were carried out under a nitrogen atmosphere using an MBraun glovebox, standard vacuum-line, and Schlenk techniques. Solvents were purchased from Sigma-Aldrich (HPLC grade) and dried using an MBraun MBSPS800 purification system. All reagents were purchased from commercial suppliers (Aldrich) and used as received unless stated otherwise. NMR spectra were recorded on a Broker AV-300, AV-400 and AV-500 spectrometers and referenced to the residual NMR solvent signals. ¹ H NMR spectra are referenced to the residual solvent peak at 5 7.26 ppm for CDCI3. Differential scanning calorimetry (DSC) analyses for determination of the glass transition temperatures (T _g ) were measured under a N ₂ atmosphere using a Mettler Toledo equipment (model DSC822e). Samples were weighed into 40 pL aluminum crucibles and subjected to three heating cycles that covered the range from 30 to 150 °C at a heating rate of 10 °C/min. Thermogravimetric analyses (TGA) were recorded under a N ₂ atmosphere using a Mettler Toledo equipped model TGA/SDTA851 . Number-average molar mass (M _n ), mass-average molar mass (M _w ) and their distributions (D) of the terpolymers were determined by gel permeation chromatography (GPC). GPC analyses were carried out with a PSS SDV Linear M (300 x 8 mm, 5 pm nominal particle size). Measurements were performed at 30 °C at a flow rate of 1 mL/min using a Rl detector (Agilent, model G1362A) and using THF as solvent. Samples were analyzed at a concentration of 1 mg-mL" ¹ . M _n , M _w , and M _w /M _n (D) data were derived from the Rl signal by a calibration curve based on polystyrene standards.

Commercial CO ₂ was obtained from Air Liquide and used without further purification. The commercially available epoxide substrates 3-vinyl-7-oxabicyclo[4.1 .0]heptane (mixture of isomers) and cis/trans-(R)-limonene oxide (LO, cis/trans (4F?)-1 -methyl-4-(prop-1 -en-2-yl)-7- oxabicyclo[4.1.0]heptane) and nucleophilic additive bis(triphenylphosphine)iminium chloride (PPNCI) or bis(triphenyl-l5-phosphaneylidene)-l4-azane chloride salt were used as received. Tris(3,5-dimethyl-2-hydroxybenzyl)amine and its aluminum complex (AIMe) were prepared as described in Supporting Information document for J. Am. Chem. Soc. 2013, 135, 1228-1232 - page S2, inserted herein by reference, starting from the ligand as prepared in J. Am. Chem. Soc. 2000, 122, 1067-1068 (compound 5), inserted herein by reference, and used after drying under vacuum at 40 °C for 24 h.

Diglycidyl ether of bisphenol A (DGEBA, Sigma-Aldrich, M _w 340.4 g/mol, EEW 172-176 g/eq) was used as received. Diethylenetriamine (DETA, Sigma-Aldrich); branched polyethylenimine (Lupasol PR 8515, BASF SE, M _w 2000 g/mol, AHEW 37 g/eq, hereinafter referred to as “PEI”), polyoxypropylenediamine (Jeffamine® D-400, Huntsman International LLC, AHEW 1 15 g/eq, average molecular weight 430 g/mol, CAS number 9046-10-0, hereinafter referred to as “Jeff”) and Crayamid® 195X60 (Arkema Coatings Resins, AHEW 240 g/eq, CAS number 1380300- 09-3, hereinafter referred to as “Cray”) were used as hardeners; and Accelerator® 960-1 (CAS number 90-72-2) was used as catalyst. Solvents used in the present study were all supplied from Panreac Chemical Spain, in analytical grade. For the high-solid epoxy formulation, the following materials were employed: benzyl alcohol (ReagentPlus®, Sigma-Aldrich Corporation), titanium dioxide (Oxined bianco, Euro Pigments), defoamer/air release agent (BYK-A 530, CAS number 63148-53-8, BYK Additives & Instruments), and silica nanoparticles (Si-NPs) prepared following the procedure described in Stober, W., Fink, A. i Bohn, E. Controlled growth of monodisperse silica spheres in the micron size range. A: Journal of Colloid and Interface Science 1968, Vol. 26, num. 1 , p. 62, incorporated herein by reference. Aluminium sheets (AA2024 alloy, 5.0 x 1.5 x 0.3 cm ³ ) were used as substrates for electrochemical impedance spectroscopy (EIS) tests. Saloclean 667N (Klintex Insumos Industriais Ltda.) was the degreasing agent used for the pre-treatment of aluminium sheets.

Preparative Example 1 : Preparation of Doly(limonene) carbonate oxide (PLCO)

All reactions were prepared in a glovebox using a 1 L Mettler Toledo Labmax reactor. In a typical experiment, (S)-3-vinyl-7-oxabicyclo[4.1 .0]heptane

(650 g, 700 mL, 4.27 mol, 1 equiv.), the catalyst [Al-Me] (22.0 g, 42.7 mmol, 0.01 equiv., 10 mol%) and the cocatalyst/nucleophile PPNCI (12.3 g, 21.4 mmol, 0.005 equiv., 5 mol%) were mixed in in a 1000 mL steel vessel equipped with a magnetic stirring bar, placed in a stainless-steel reactor. This reactor was connected to a 300 mL stainless steel reactor which was filled with CO2. Three cycles of pressurization and depressurization of the reactor with CO2 (5 bar) at room temperature (r.t.) were carried out before finally stabilizing the pressure at 15 bar. The reaction was stirred at 45 °C for 118 h at 640 rpm. Finally, the reaction was stopped, and the reactor was allowed to cool down to room temperature before venting. The crude reaction mixture was dissolved in DCM (1 L). An aliquot was analyzed by ¹ H NMR spectroscopy to determine the conversion to polymer. The reaction mixture was concentrated (890 g) and was poured dropwise into methanol (8.5 L) under stirring. A whitish sticky solid was obtained. Supernatant was removed and after solvent evaporation stones were obtained. The stones were reduced to powder and were poured into MeOH. The mixture was stirred for 16 h, the solid was filtered, washed with MeOH and dried at 50 °C in vacuum for 20 h to yield the product as a white solid.

Conversion = 50%. Yield = 32.5%.

M _n = 5.56 kDa, M _w = 7.60 kDa, B = 1 .36.

T _g = 103.3 and 106.2 °C.

¹ H NMR (400 MHz, CDCI ₃ ) 6 5.22 - 4.94 (m, 1 H), 4.78 - 4.64 (m, 2H), 2.50 - 2.30 (m, 1 H), 2.30 - 2.1 1 (m, 1 H), 1 .96 - 1 .81 (m, 1 H), 1.80 - 1 .66 (m, 5H), 1.66 - 1 .57 (m, 1 H), 1.52 - 1 .45 (m, 3H), 1 .44 - 1 .28 (m, 1 H) ppm.

¹³ C NMR (101 MHz, CDCI ₃ ) 5 152.1 , 148.8, 109.5, 81.9, 75.5, 37.7, 31.0, 30.7, 26.0, 21.7, 20.8 ppm.

In a typical procedure, ( 1S,2S)-2-methoxy-2-methyl-5-(prop-1 -en-2-yl)cyclohexyl methyl carbonate (5.0 g, 25.5mmol, 1 equiv.) was dissolved in DCM (100 mL) and the flask placed in a water bath. 3-chlorobenzoperoxoic acid (m-CPBA) (8.56 g, 77% wt., 38.2mmol, 1.5 equiv.) was added portion-wise as a solid. The mixture was stirred at 25 °C for 20 h. The formed suspension was filtered and then 120 mL saturated NasSOs solution was added under vigorous stirring for 30 min to quench the excess of m-CPBA. Phases were separated and saturated NaHCOs solution was added to the organic phase under vigorous stirring. After phase separation, the organic phase was washed with brine, dried over MgSC and all volatiles were removed in vacuo. The polymer was additionally purified by precipitation with MeOH from DCM, obtaining the product as a slight yellow solid. A second precipitation was performed by dissolving the solid in DCM and adding onto MeOH, obtaining 4.45 g of solid.

Conversion = 97%. Yield = 82.3%.

M _n = 6.00 kDa, M _w = 8.03 kDa, B = 1 .33.

T _g = 125.9 and 125.4 °C. ¹ H NMR (500 MHz, CDCI ₃ ) 6 5.22 - 4.93 (m, 1 H), 2.68 - 2.48 (m, 2H), 2.46 - 2.24 (m, 1 H), 2.00 - 1 .79 (m, 1 H), 1 .78 - 1 .52 (m, 4H), 1.52 - 1 .42 (m, 3H), 1 .40 - 1 .29 (m, 1 H), 1 .27 - 1.15 (m, 3H) ppm.

Example 1 : Preparation of a polvepoxide deriving from a polycarbonate copolymer of limonene oxide and vi oxide PLCDE n:m ca. 10:1

In a typical experiment, a mixture of 3-vinyl-7-oxabicyclo[4.1 ,0]heptane (1.34 g, 10.8 mmol, 0.1 equiv.) and (F?)-1 -methyl-4-(prop-1 -en-2-yl)-7-oxabicyclo[4.1.0]heptane (16.4 g, 17.7 mL, 108 mmol, 1 equiv.) was azeotropically distilled with dry toluene (2 x 1 mL) prior to addition into a Teflon vessel equipped with a cross-magnetic stirring bar and containing the catalyst [Al-Me] (651 mg, 1.20 mmol, 0.01 equiv., 10 mol%), the co-catalyst/nucleophile bis(triphenylphosphine)iminium chloride PPNCI (344 mg, 600 pmol, 0.005 equiv., 5 mol%) and the remaining dry toluene (3 mL). Three cycles of pressurization and depressurization of the reactor with CO2 (5 bar) at room temperature were carried out before finally stabilizing the pressure at 15 bar. The reaction was stirred at 45 °C (55 °C outside the reactor) with a metallic heating block for 68 h at 600 rpm. Finally, the reaction was stopped, and the autoclave was allowed to cool down to room temperature before venting. The crude reaction mixture was dissolved into a minimum amount of DCM. An aliquot was analyzed by ¹ H NMR spectroscopy to determine the conversion to polymer. The reaction mixture was concentrated (40 mL) and was poured dropwise into acidified methanol (440 mL) under stirring. A yellow sticky solid was obtained. Supernatant was removed and after solvent evaporation a yellow foam was obtained.

Conversion = 71% of LO and full conv. of vinyl epoxide. Yield = 54.5%.

M _n = 3.85 kDa, M _w = 5.33 kDa, D = 1 .38.

T _g = 74.50 and 75.17 °C.

¹ H NMR (300 MHz, CDCI ₃ ) 6 5.88 - 5.65 (bs, 0.1 H), 5.09 (d, J = 19.5 Hz, 1 H), 4.94 - 4.85 (m, 0.1 H), 4.85 - 4.59 (m, 2H), 2.53 - 2.30 (m, 1 H), 2.30 - 2.12 (m, 1 H), 1 .98 - 1 .80 (m, 2H), 1.80 - 1 .67 (m, 4H), 1 .67 - 1 .53 (m, 2H), 1.53 - 1 .43 (m, 2H), 1 .43 - 1 .27 (m, 1 H) ppm.

In a typical procedure, 2-(((((1 S,2S)-2-methoxy-2-methyl-5-(prop-1 -en-2- yl)cyclohexyl)oxy)carbonyl)oxy)-5-vinylcyclohexyl acetate (12.5 g, 56.3/58.7 mmol, 1 equiv.) was dissolved in DCM (200 mL) and the flask placed in a water bath. 3- chlorobenzoperoxoic acid (m-CPBA) (17.1 g, 77% Wt, 76.3 mmol, 1.3 equiv.) was added portion-wise as a solid. The mixture was stirred at 25 °C for 20 h. The formed suspension was filtered and then 120 mL saturated NasSOs solution was added under vigorous stirring for 30 min to quench the excess of m-CPBA. Phases were separated and saturated NaHCOs solution was added to the organic phase under vigorous stirring. After phase separation, the organic phase was washed with brine, dried over MgSC and all volatiles were removed in vacuo. The polymer was additionally purified by precipitation with MeOH from DCM, obtaining the product PLCDE as a slight yellow solid.

Conversion = 99%. Yield = 92%.

M _n = 4.17 kDa, M _w = 5.88 kDa, £> = 1.41.

T _g = 132 °C.

¹ H NMR (300 MHz, CDCI ₃ ) 6 5.21 - 4.97 (m, 1 H), 4.97 - 4.85 (m, 0.2H), 4.85 - 4.74 (m, 0.2H), 2.87 - 2.71 (m, 0.5H), 2.71 - 2.49 (m, 3H), 2.49 - 2.16 (m, 1 H), 2.04 - 1 .80 (m, 2H), 1.80 - 1.52 (m, 8H), 1.52 - 1.44 (m, 3H), 1.34 - 1.15 (m, 5H) ppm. lm preparation from PLCO and thermoset curinq for the of a heat-curable resin The compositions of polyepoxide:hardener were defined taking into account the epoxy equivalent weight - EEW - of PLCO (216 g/eq) or DGEBA (172-176 g/eq) and the amine hydrogen equivalent weight - AHEW - of the hardeners . Samples were prepared using the stoichiometric proportions of 2:1 , 1 :1 and 1 :2 for polyepoxide:hardener, i.e. the theoretically necessary amount of both components in order to have each epoxy group reacting with one amine functionality in case of 1 :1 ratio; or an excess of hardener in case of 1 :2 ratio; or an excess of epoxy, in case of 2:1 ratio. The amount of Accelerator® 960-1 catalyst was constant for all formulations in which it was tested (2 % by weight). Table 1 summarizes the main properties of the raw materials used in the preparation of heat-curable resin compositions. To prepare the composition, polyepoxide PLCO or DGEBA (component A, 100 mg) was initially dissolved in a small proportion of xylene (50 pL/g of epoxy) and, after dissolution, it was mixed with the necessary amount of hardener (component B, Table 2). The components A and B (and, when present, the catalyst) were vigorously stirred at room temperature. The mixture was then poured into a glass Petri dish, covered by Teflon films, and left overnight in a ventilation hood for solvent evaporation. The samples were then pre-cured under vacuum for 2 hours at 120 °C in order to activate the initial cross-linking process and remove all residual hydrocarbon solvent.

Table 1 . Chemical data for the raw material used in the present work.

„ _x . , Aspect M _w ^a) EEW ^b > AHEW ^C >

Raw material . . . . . . . .

(g/mol) (g/eq) (g/eq)

PLCO Powder ~ 9000 216-220

DGEBA ^d > Viscous Liquid 340.4 172-176

DETA ^d > Liquid 103.5 - 21

PEI ^d > Liquid 2000 - 37

Jeff ^d > Liquid 430 - 1 15

Cray ^d) Liquid - - 240-270 ^a) Data acquired by gel permeation chromatography; ^b) calculated by M _w /n, being “n” the number of epoxy units; ^c) calculated by M _w /n, being “n” the number of reactive hydrogens from amine groups; ^d) information available from commercial datasheets.

Table 2. Proportions of the components used in the studied compositions.

Molar Epoxy Hardener Solvent

Entry Epoxy:Hardener ratio amount amount volume

(mg) (mg) (pL)

1 PLCO:Jeff 1 :1 100 46.3 50

2 PLCO:Jeff 1 :2 100 92.6 50

3 PLCO:Cray 1 :1 100 11 1.0 50

4 PLCO:Cray 2:1 100 55.5 50

5 DGEBA:Jeff 1 :1 100 66.1 50

6 DGEBA:Cray 1 :1 100 138.1 50

7 PLCO:DETA 1 :1 100 9.5 50

8 PLCO:PEI 1 :1 100 17.2 50

Entries 5, 6, 7 and 8 are comparative examples: entries 5 and 6 use a polyepoxide falling outside the scope of the invention (DGEBA) and entries 7 and 8 employ a hardener having AHEW values outside the scope of the invention. Materials obtained from the compositions of entries 7 and 8 after curing were found too brittle and of insufficient quality in terms of film stability.

After curing, thermoset chemical composition was evaluated with Fourier-transform infrared (FTIR) spectroscopy. A Jasco 4100 spectrophotometer, coupled with an attenuated total reflection accessory (Specac model MKII Golden Gate Heated Single Reflection Diamond ATR), allowed the monitoring of the crosslinking reactions among polyepoxide and hardener. Cured thermoset films were characterized by isothermal FTIR-ATR, and compared with the FTIR-ATR spectra of raw materials, showing the formation of the molecular fragment and - NR-CH ₂ -C(OH)- by opening of the oxirane moiety.

Dynamic DSC tests were carried out with the pre-cured samples in order to assess the final curing temperature for each composition (T _g °°), identified by an exothermal peak in the first thermal sweep of the specimens. The kinetics of the curing have been evaluated by calorimetry, using a TA Instruments Q100 series equipped with a refrigerated cooling system and operating under nitrogen atmosphere. First, the films have been cured isothermally at 120 ^e C for 2 hours. After that, two dynamic scans have been performed from - 90 to 200 - 250 ^e C (depending on the stability of the samples), at 10 ^e C/min. In the first scan, the initial glass transition temperature (T _g °) has been determined, and in the second scan the ultimate T _g (T _g °°) has been obtained. Figure 1 shows the first and second heating curves from non-isothermal DSC curves of the biobased thermoset materials of entries 1 to 4 of Table 2.

For the isothermal experiments, the protocol consisted in heating the pre-cured samples (2 hours at 120 °C) until the temperature in which the curing exothermal peak was first observed (first sweep in dynamic measurements) at 10 °C/min. Once this temperature was reached, it was maintained for two hours in order to promote an isothermal curing and assure the full curing of the polymers. The integration of the observed curing peak during the isothermal curing step provided the curing degree of the studied compositions. After two hours of isothermal curing, the samples were cooled to - 80 °C and heated at 10 °C/min until sample degradation was observed. The total heat of curing (AC _P ) can be measured in the isothermal curing step carried out in the calorimeter. The degree of epoxy conversion (%) was calculated from the isothermal DSC, following the equation 1 :

A

DC _t = x 100 Eq. (1 ) where DC _t is the degree of epoxy conversion, in %, at the time t, A _t is the area of the curing peak at the time t and A is the area of the entire curing peak after full curing is achieved. The calorimetry data are described in Table 3. Thermogravimetry (TGA) was performed under nitrogen atmosphere with a Q50 (TA Instruments) equipment at 10° C/min in the range between 30 ^e C and 600 °C. This test was carried out with fully cured samples to evaluate the thermal stability of the thermosets. The maximum decomposition temperatures (T _d , _ma x) are described in Table 3.

Table 3

Observing the T _g values, it is possible to certify that the polymer chain mobility within the cured material is determined by each of the curing agent or the composition ratio of PLCO:hardener mixtures. For example, using Jeff as hardener, PLCOJeff (1 :1 ) is more rigid (T _g °° of 61.5 ^e C) than PLCOJeff (1 :2) and more rigid than DGEBAJeff (1 :1 ) cured at room temperature, which is attributed to the constrained chemical structure of poly(limonene carbonates) (PLC). Additionally, an increase content of Jeff leads to an abrupt decay on the glass transition temperature from 61.5 ^e C (PLCOJeff 1 :1 ) to 12.3 ^e C (PLCOJeff 1 :2), giving rise to more flexible thermoset chains at room temperature. By contrary, when Cray is used as hardener in the proportion of 1 :1 , i.e. the PLCO:Cray (1 :1 ), it has thermal properties similar to PLCOJeff (1 :2), including the time necessary to reach 100 % of epoxy conversion (41 min and 37 min, respectively), determined by isothermal DSC.

These results suggest that PLCO is more reactive with polyetheramines (such as Jeff), with which a stoichiometric ratio of 1 :1 is completely cured after 30 min.

The shortest curing times were observed for DGEBA: Cray 2:1 (1 1 min), followed by PLCOJeff 1 :1 (30 min); whereas the lowest reactivity was obtained for PLCO:Cray 2:1 (59 min). Calorimetry studies indicate a higher reactivity for the Jeff-containing compositions than for the Cray-based thermosets, as the complete curing was achieved after shorter periods for the former than for the latter. Polyetheramines such as Jeff are thus preferred hardeners when high reactivity of the composition is sought. When comparing the composition according to the invention with the ones based on the synthetic polyepoxide DGEBA (three last rows of Table 3), although the latter is a more reactive polyepoxide at room temperature, PLCO offers similar thermal properties for the curable composition as DGEBA. Consequently, PLCO is a suitable polyepoxide for applications such as stoving enamels, which are paints that cure at elevated temperatures. Moreover, PLCOJeff and PLCO:Cray can resist to degradation temperatures (T _d , _ma x) as high as 220-250 ^e C, in compliance with the effective stoving temperatures for stoving enamels, that is typically between 80 ^e C and 250 ^e C. Finally, the VOC content (in g/L) used to dissolve the PLCO powder does not increase if compared to the DGEBA formulations known in the art, representing another interesting advantage to replace low molecular weight DGEBA resin (many times supplied previously dispersed in xylene), by solid epoxy PLCO product (high molecular mass). PLCO may thus be used as a substitute for DGEBA in curable compositions comprising amine hardeners as defined above.

The mechanical properties were evaluated at room temperature, using a universal testing machine (Zwick BZ2.5/TN1 S) with specially designed grips. The specimens were sized in rectangular shape of 30 x 3 mm ² and variable thicknesses. The experiments were performed at a crosshead speed of 5 mm/min and with a preload of 0.05 MPa. The results were expressed as strength versus elongation at break curves and are further disclosed in Table 4.

Table 4

. . . Molar CT _max Young modulus s _b r _e ak

Epoxy:Hardener

^{K J} ratio (MPa) (MPa) (%)

PLCOJeff 1 :1 26.3 ± 1.3 5.2 ± 1.0 19.6 ± 5.8

PLCOJeff 1 :2 3.9 ± 1.5 - 68.0 ± 8.8

PLCO:Cray 1 :1 7.2 ± 1.2 2.1 ± 0.1 3.5 ± 0.5

PLCO:Cray 2:1 4.1 ± 0.7 2.8 ± 0.1 1.5 ± 0.2

Inventors found in particular that, when the amount of polyepoxide PLCO is increased, the resulting material exhibits increased stiffness. Also, it was found that, when the amount of hardener is increased, the resulting cured material becomes more flexible. The cured material based on PLCOJeff in a 1 :1 ratio exhibits a high value of maximum tensile strength, which makes this material particularly suitable for protective epoxy coating applications. These data also suggest that increasing the AHEW of the amine component produces more brittle materials. It is thus possible to modulate the mechanical behaviour of bio-based thermoset materials according to the invention by combining different molar ratios of hardeners and/or AHEW values of hardeners. Compositions comprising a super-stoichiometric amount of hardeners are preferred for adhesives and coil coating applications because it is known in the art that an excess of hardener in the resin formulation provides enhanced adhesion at the expense of solvent resistance. On the other hand, a resin comprising a super-stoichiometric amount of the polyepoxide (such as PLCO) is suitable for protective coating applications, because the produced thermoset material typically exhibits a high Young modulus.

In order to assess the polymer permeability as a primer, samples for EIS tests were prepared using AA2024 alloy substrates and PLCO:Jeff in a molar ratio 1 :1. These substrates were polished to #2500 grit and went through an alkaline degreasing procedure (pH 9.4, 70g/L, 70 ^e C) during 5 minutes, followed by rinsing with deionized water and drying. Afterwards, a nanometric layer of ZrO ₂ was applied in each sample to create a passivating layer for further polymer anchoring. The inorganic layer was deposited with electrochemical method, by using an aqueous solution prepared with 100 mg of H ₂ ZrF ₆ in 1 L of water (0.015% v/v, pH 3.5), and applying a potential of -1 .0V for 4 minutes. Then, the thermoset film was applied on the metallic substrates and followed the abovementioned curing procedure. The dry film thickness was 238 ± 20 pm.

The EIS experiments were carried out using an Autolab PGSTAT302N potentiostat/galvanostat (Ecochemie). A three-electrode cell configuration was used, with a Ag | AgCI (KCI, 3 M) reference electrode and a platinum counter electrode with 0.05 M NaCI as electrolyte. The coated aluminium sheet was the work electrode in this setup. An area of 0,785 cm ² was used for the measurements. After 30 minutes of open circuit potential stabilization an alternate potential with 10 mV amplitude was applied in frequencies ranging from 10 ⁵ to 10 ^-1 Hz, with 10 measurements per decade in logarithmic distribution. The measurements were performed after specific periods of exposure of the sample to the electrolyte, which were: 1 , 3, 5, 9, 12 and 15 hours.

The experimental data were fitted with the Randles circuit (R _s [Rc-CPE _c ]) to achieve the electrical equivalent circuit (EEC) parameters expressed in Table 5.

Table 5 posure R _s R _c CPE _c e (h) (Q cm ² ) (Q cm ² ) (F-cm ^-2 -s ⁿ ' ¹ ) ^ncPE

1 368 1.13 x 10 ¹¹ 5.03 x 10 ¹¹ 0.96

3 321 5.79 x 10 ¹⁰ 5.80 x 10' ¹¹ 0.96

5 390 3.35 x 10 ¹⁰ 6.49 x 10 ¹¹ 0.95

9 345 1.92 x 10 ¹⁰ 7.02 x 10 ¹¹ 0.95

12 340 1.65 x 10 ¹⁰ 8.19 x 10 ¹¹ 0.94 15 366 1.28 x 10 ¹⁰ 8.32 x 10 ¹¹ 0.94 The results of Table 5 indicate that the coating resistance (R _c ) has been reduced by one order of magnitude only after 3 hours of immersion and then remains in the same range up to 15 hours of immersion, which represents a minimal loss of insulating properties of the film. Moreover, the non-ideal capacitance (CPE _c , constant phase element), which is the parameter attributed to the surface reactivity, surface heterogeneity, and roughness regarding to current and potential distribution, is maintained very low all along the immersion. These results suggest that PLCO:Jeff (1 :1 ) is a promising candidate for coatings and adhesive technologies.

Example 3: Epoxy film preparation from PLCDE and thermoset curing

Preparation procedure 1 : The total weight mass prepared of Component A (mixture of polyepoxides) was 50 g. An amount of PLCDE and, optionally of DGEBA, was poured into a disperser vessel (250 mL) (Dispermat TU, VMA Getzmann GmbH) equipped with a cowles disperser blade, and mixed with 2 mL of xylene per gram of polyepoxide for homogenization, thereby producing component A. Afterwards, curing agent Jeff (23,45 g, 24,1 mL) was incorporated to component A and left to stir with the epoxy predispersion. Adjustment of the cowles disperser to a speed of 8000 rpm and 15 min of time produced the solvent-borne epoxy resin. Optionally, an accelerator agent Accelerator® 960-1 (2 weight % with respect to polyepoxide) is added and the mixture is left to stir 5 min, to avoid solidification inside the reactor vessel. Finally, the solution is turned over Teflon (Teflon is PTFE) moulds for drying and curing processes.

For the stoving drying process, the moulds were left in an oven at 120 ^e C for 1 h in a first step and at 150 ^e C for 2 h for a second step in order to achieve the complete crosslinking. Alternatively, when the catalyst (accelerator agent) is added, the films dry to touch after 24 h at room temperature and relative humidity of 85 %. The complete curing was achieved after 7 days at r.t., according to calorimetry analysis.

The following formulations were prepared according to the abovementioned procedure (Table 6):

Table 6 Differential scanning calorimetry (DSC) at temperatures from -60 °C to 200 °C was performed using a Perkin Elmer model Pyris I instrument equipped with a refrigerated cooling system operating under nitrogen atmosphere (50 mL/min). Samples were heated from -60 to 200 °C, at a constant heating rate of 10 °C/min, working with 5 mg of samples placed in sealed aluminium pans. Second order transitions (T _g ) were determined by the StepScan DSC technique that yields enhanced characterization information by separating out the reversible and irreversible thermal events. The glass transition temperature (Tg”) of each cured sample was determined by the second heating scan (20°C/min). Thermogravimetric analysis (TGA) was carried out with a Mettler Toledo TGA2 equipment from 30 °C to 600 °C at a heating rate of 10°C/min, under nitrogen atmosphere, and by placing 10 mg of cured sample in the holder. The results of these experiments are shown in Figure 2.

As shown in Figure 2, the enthalpy released per gram of sample (AC _P ) is similar for both samples, whether cured at room temperature or by stoving. If compared to the PLCDE prepolymer and DGEBA commercial resin (132 ^e C and 100 ^e C, respectively), the low T _g ” of PLCDE:Jeff (1 :1 ) of about 50 ^e C is advantageous, because working at higher temperatures can lead to loss of chemical resistance. In adhesive technology, it is indeed preferred to apply the epoxy above its T _g , as it makes the bonding more shock and vibration resistant. Moreover, the epoxy is also less likely to damage fragile components as a result of its lower rigidity.

The suitability for adhesive applications of the formulations of examples 3-2, 3-3 and 3-4 was then studied. The adhesion strength of the formulations of examples 3-2, 3-3, 3-4 deposited on AA2024 rectangular pieces (40x30x3 mm ³ ) was determined by pull-off test by using a KN- 10 adhesion equipment (Neurtek S.A.) and following UNE-EN-ISO 4624 standard. For dry adhesion the thus produced coated panels and dolly (20 mm in diameter), were bonded using a two-component epoxy adhesive Araldite® 2020 (Product code Huntsmann: 00052144, Mixture consisting of 30-60% bisphenol A-(epichlorhydrin) epoxy resin (number average molecular weight < 700 - CAS: 25068-38-6) and 30-60% 1 ,4-bis(2,3-epoxypropoxy)butane as epoxy component A; and Product code Huntsmann 00047541 , Mixture consisting of 30-60% 3-aminomethyl-3,5,5-trimethylcyclohexylamine and 13-30% trimethylhexane-1 ,6-diamine as hardener component B). After 24 h of adhesive cure, a slot was cut around the dolly at the substrate boundary to avoid the effect of peripheral coatings. At least ten independent measurements for each system were made, those with interfacial failure were considered and the minimum force to detach the coatings from substrate was recorded accordingly. The pull- off strength force average for each system is reported in Table 7, together with the film thickness. Table 7

Thickness and Adhesion force Type of

^Xam P ^e deviation(pm) (MPa)

3-2 46.3 ± 8.1 3.70 ± 0.87

3-3 56.3 ± 17.7 2.30 ± 0.79

3-4 38.1 ± 8.7 1.91 ± 0.42 ^a) -/Y, according to UNE-EN-ISO 4624 standard, refers to adhesive break between the last coating layer and the adhesive.

The mechanical properties of the bio-based epoxy thermosets were evaluated through stressstrain assays with a Zwick Z2.5/TN1 S testing machine. Plate samples with a length of 30 mm, a width of 3 mm and a thickness of 100-250 pm were cut out from films deposited on Teflon and cured according to the procedure described above. The deformation rate was 10 mm-min ^{_ 1} . All the mechanical parameters reported below were obtained by averaging the results obtained from ten independent measurements. The values of elastic modulus, maximum tensile stress and elongation at break are reported in Table 8.

Table 8

._ , ._. _x . . , . Maximum tensile Elongation at rupture

Example Elastic modulus (MPa)

^{K v} _{x X1} ' strength (MPa) (%)

3-2 663.5 ± 98.9 26.3 ± 1.3 20.8 ± 9.7

3-3 345.6 ± 63.8 10.2 ± 1.1 16.9 ± 5.8

3-4 758.5 ± 78.4 17.8 ± 1.3 3.3 ± 0.2

As all of the tested samples presented adhesive type failure (Table 7), the measured strength refers to the adhesion between the commercial epoxy adhesive used for such purpose, and the biobased epoxy film. The highest values were obtained for the PLCDE:Jeff (1 :1 ) sample (3.70 ± 0.87 MPa), which also has the highest tensile strength (26.3 ± 1 .3 MPa) and elongation at break (20.8 ± 9.7 %), see Table 8 (Example 3-2). The adhesion for the DGEBA-free formulation is comparable to other DGEBA-based epoxy coatings and surpasses that of other partially biobased epoxy systems known in the art. Moreover, reduction on PLCDE content respect to DGEBA component, leads to a worsening of the mechanical properties of the films, which becomes more rigid and more brittle (high elastic modulus and low elongation at break) (Example 3-4). Example 4: Preparation of solvent-free two components partially bio-based epoxy paint formulation

A paint formulation suitable for self-levelling of building structures, coating mineral substrates, mortars and concrete or as anti-corrosion coatings for steel structures was prepared as follows: 8.46 g of PLCO (solid) were mixed with 33.82 g of DGEBA (liquid), without solvent. This proportion was intended calculated to have 20 weight % of biobased epoxy (PLCO) respect to 80 weight % of synthetic one (DGEBA). Afterwards, 5.01 g of TiOs (white pigment) and 48.67 g of silica nanoparticles (fine powder used as filler) were added, followed by 2.02 g of BYK A530 (liquid defoamer, 41 pL) and 2.02 g of benzyl alcohol (solvent, 38 pL). Then the mixture was milled with a mortar, until obtaining a homogenous and consistent paste, thereby producing a component A (total weight mass equal to 100 g). Then, 14.75 g of a hardener (Jeffamine hardener Jeff, 0,313 mL), representing component B, was added and left to react with Component A for 30 min, while mixing by hand. The resulting paste was then applied to a Teflon substrate to get films for physical-chemistry evaluation. The films were post-cured in an oven, at 150 ^e C for 2 hours, to ensure the complete curing of the less reactive PLCO molecules. Optionally, 2 wt. % of catalyst Accelerator® 960-1 (CAS number 90-72-2, 2 grams of catalyst per each 100 grams of polyepoxide) can be added to accelerate the curing process without stoving conditions. Table 9 shows the chemical formulation in weight percentage of the prepared Component A for the epoxy resin formulation (wt. %), without catalyst.

Moreover, the classification “solvent-free coating” is based on a very low content of the solvent (< 2 pbw - parts by weight), which is indispensable to prepare a homogeneous paste and advantageously allows minimalizing the VOC footprint of the epoxy formulation.

The infrared and TGA characterization were performed with the same equipment and procedures explained above (Example 2).

Table 9 The solid film obtained after post-curing treatment does not present any specific coloration. The absence of coloration is desirable for certain applications such as mortars or cements. In addition, comparing the thermal stability of the PLCO/DGEBA:Jeff new coating of this Example 4 with that of pure PLCO:Jeff (1 :1 ) composition (Example 1 ), the results corroborates the previous thermal results of Example 2. Two degradation steps are observed: a first one at 248 ^e C and a second one, more prominent, at 359 ^e C. The first decomposition decay (248 ^e C) is attributed to the PLCO content, and it is proportional to the amount added in the paste formulation. The second step can be related to the DGEBA-PLCO blend, because it coincides with the Td.max showed for PLCOJeff (1 :1 ) and is slightly inferior to the pure DGEBA:Jeff (1 :1 ) thermoset composition. The high-solid content is evidenced by the char yield at 600 ^e C (47%), which correspond to the sum of TiOs and filler. This Example shows that a bio-based polyepoxide as defined in the first aspect of the invention can also be used as partial replacement of synthetic epoxides (such as DGEBA) in commercial formulations of epoxy resins without causing the cured material any loss of thermal stability. Since PLCO derives from both biomass (limonene) and carbon dioxide, such formulations advantageously exhibit a reduced environmental footprint.

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