Curable composition comprising a polythiol

Abstract

The present invention relates to curable compositions comprising a) a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups and b) a component comprising one or more ethylenically unsaturated compounds. The invention also relates to a method of making cured compositions, comprising curing the curable composition, and their use for adhesives, inks, 3D printing materials, sealants, coatings, photosensible materials, composites, among other potential applications.

Description

CURABLE COMPOSITION COMPRISING A POLYTHIOLFIELD OF THE INVENTION

[0001] This invention relates to curable compositions comprising a) a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups and b) a component comprising one or more ethylenically unsaturated compounds. The invention also relates to a method of making cured compositions, comprising curing the curable composition, and their use for adhesives, inks, 3D printing materials, sealants, coatings, photosensible materials, and composites, among other potential applications.BACKGROUND

[0002] In the past few years, there has been a notable increase in the utilization of cured resin products, particularly those incorporating thiol compounds, across a diverse array of industries. These resin formulations, having undergone a curing process, offer enhanced properties such as durability, strength, and chemical resistance, making them versatile for numerous applications. Thiol compounds, characterized by their sulfhydryl (-SH) functional groups, play a pivotal role in these formulations, imparting specific attributes such as rapid cross-linking, delayed gelation, reduced shrinkage and reduced stress.

[0003] Despite their advantages, the use of thiols presents significant drawbacks, notably the limited stability of the curable compositions, which can adversely affect shelf-life stability of the compositions incorporating them. Indeed, commercially available polythiols, commonly employed in photocurable thiol-ene formulations, are prone to premature dark polymerization. The addition of a high quantity and / or specific stabilizers is one of the most used solutions, but itself comes with the major drawback that it may involve coloration / yellowing issue.

[0004] The stability of thiol-ene compositions has been reported to improve with the use of secondary polythiols. Showa Denko (now Resonac) commercializes the pentaerythritol tetrakis (3- mercaptobutylate) poly thiol under the tradename KarenzMT™ PEI, manufactured via the esterification of 3-mercapto butyric acid with polyols. However, the presence of ester functions has been shown to result in lower thermal and water / alkali resistance, leading to degradation of the material and potentially compromising its performance in applications where thermal stability and resistance to moisture or alkaline environments are crucial.

[0005] In order to solve these issues, JP2012153794A and JP2011032201 A describe the use of ester- free and / or ether free poly thiols.

[0006] In particular, JP2012153794A (SAKAI CHEMICAL INDUSTRY CO) describes a resin composition and a cured resin product, where the resin product is presented as having an improved water resistance. The resin composition includes a cyclic thiol compound and a compound having any of a vinyl group, a vinyl ether group, an acrylate group, a methacrylate group, an allyl ether group, or an epoxy group. More precisely, the cyclic thiol compound is represented by the following formula:wherein A is a ring structure, Ri and R2 represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, n represents an integer from 0 to 4, m represents an integer from 2 to 6. Ring structures with a benzene ring, a cyclohexane ring, a tetrahydrodicyclopentadiene ring, or an isocyanurate ring are essentially described and preferred. The resin compositions in the examples include an epoxy compound or a trimetho xyvinylsilane, in combination with one of the five following thiols:However, polythiols (2), (5) and (6) derived respectively from a tetrahydrodicyclopentadiene ring (DPT), cyclohexane ring (DMCH), and a benzene ring (MXDT), are dithiols that do not promote the formation of highly crosslinked (dense) networks, resulting in lower glass-transition temperature (Tg) and diminished thermal and mechanical properties. Furthermore, compound (6) is particularly prone to yellowing, especially due to its aromatic nature. Additionally, compounds (3) to (6) are primary thiols, inherently exhibiting lower stability.

[0007] As far as JP2011032201 A (RESONAC HOLDINGS CORP) is concerned, it relates to aromatic ether-based polyfunctional secondary thiols used in the resin composition presented as havingwater resistance, alkali resistance and heat resistance when used in photosensitive thiol-ene compositions. More precisely, the document relates to a thiol compound of formula (1):wherein R1represents an alkyl group having 1 to 3 carbon atoms, R2represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms which may have a substituent, R3represents an optionally substituted alkyl group having 1 to 4 carbon atoms or an optionally substituted alkoxy group having 1 to 4 carbon atoms, m is an integer of 1 to 2, and a is an integer of 0 or 1 to 2, b is an integer of 2 to 4, c is an integer of 0 or 1 to 2, and a + b is 4. The example describes ultraviolet-curing of tris (4- (2- mercaptopropoxy) phenyl) methane (TPT) and trimethylolpropane triacrylate (TMP3A) in the presence of a photopolymerization initiator. However, the polythiols described in this document are highly aromatic, leading to potential yellowing issues. Additionally, they are very viscous and ether-based, which may also contribute to lower thermal and alkali resistance.

[0008] US2021206922A1 (RESONAC HOLDINGS CORP) also describes the use of primary or secondary polythiols to be used in thiol-ene curable compositions. The curable composition comprises a compound (A) having an isocyanuric skeleton and at least two mercapto groups in one molecule, and at least one of a compound (B) including diallyl maleate and diallyl fumarate. More precisely, the compound (A) is at least of the following thiols: l,3,5-tris(3-mercapto butyryloxyethyl ethyl)-l ,3,5- triazine-2,4,6 (1H, 3H, 5H)-trione, tris [(3-mercapto-propionyloxy)-ethyl]-isocyanurate and tris (mercaptopropyl) isocyanurate, that is highly aromatic and ester-based compounds, which make them subject to various drawbacks as discussed previously.

[0009] US9340716B2 (CHEVRON PHILLIPS CHEMICAL CO LP) discloses a polythiol composition derived from cyclododecatriene comprising sulfur-containing compounds, in particular processes for forming the polythiol composition starting from cyclododecatriene. The polythiol compositions disclosed in the document can be used as curing agents for epoxy and urethane adhesives and other articles, which can be used with, or can contain, metal (e.g., aluminum, steel, copper, etc.), wood, glass, ceramic, and plastic substrates, including combinations of these substrates.

[0010] One of the objects of the present invention is to provide a curable composition which may be efficiently cured when exposed to radiation and / or heat, present a high conversion rate and presents improved performance in terms of shelf-life stability.BRIEF SUMMARY

[0011] In a first aspect, the present invention provides a curable composition comprising: a) a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups; and b) a component comprising one or more ethylenically unsaturated compounds.

[0012] In some embodiments, the at least three -SH groups in the polythiol a) are secondary thiol groups.

[0013] In some embodiments, the at least three -SH groups are directly bonded to carbon atoms forming said cycloaliphatic ring.

[0014] In some embodiments, the polythiol a) is the trimercaptocyclododecane (also called cyclododecanetrithiol) .

[0015] In some embodiments, the component b) is an electron-deficient component and comprises at least one compound comprising one or several polymerizable group(s), preferably an acrylate functional group ( — O-C(O)-CH=CH2), a methacrylate functional group ( — O-C(O)-C(CH3)=CH2), an acrylamide functional group ( — NH-C(O)-CH=CH2), a methacrylamide functional group ( — N H-C(O)- C(CH3)=CH2), a vinyl sulfone functional group (-SO2-CH=CH2), a maleimide functional group or mixture thereof, and more preferably an acrylate functional group and / or a methacrylate functional group.

[0016] In some embodiments, the component b) is an electron-rich component, and preferably comprises at least one compound comprising a vinyl group ( — CH=CH2), a vinyl ether group ( — O- CH=CH2), an allyl group ( — CH2-CH=CH2), an allyl ether group ( — O-CH2-CH=CH2), or any mixtures thereof.

[0017] The terms “electron-deficient component” refer to a component comprising an electrondeficient double bond. The terms “electron-rich component” refer to a component comprising an electron-rich double bond.

[0018] In a second aspect, the present invention also provides the use of the curable composition of the present invention for an adhesive, an ink, a 3D printing material, a sealant, a coating, a photosensible material or a composite.

[0019] In a third aspect, the present invention provides a method of using the curable composition of the present invention for an adhesive, an ink, a 3D printing material, a sealant, a coating, a photosensible material or a composite.

[0020] In a fourth aspect, the present invention provides method of making a cured composition, comprising curing the curable composition of the present invention, for example comprising exposing the curable composition to UV / EB radiation and / or heat.

[0021] In a fifth aspect, the present invention provides a cured composition obtained by curing the curable composition of the present invention.

[0022] In a sixth aspect, the present invention provides the use of a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups, preferably the cyclododecanetrithiol, as a crosslinker agent and / or chain transfer agent for thiol-ene systems.DETAILED DESCRIPTION

[0023] In the present application:- the expression “comprised between ... and ...” should be understood as including the limits;- any description, even though described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present invention;- where an element or component is said to be included in and / or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list; and- any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents.Definitions

[0024] The term “C1-C4” as used herein refers to the number of carbon atoms comprised in a specific group or substitution. For example, a C1-C4 alkyl is an alkyl comprising from 1 to 4 carbon atoms.

[0025] The term “alkyl” as used herein means a monovalent saturated acyclic hydrocarbon group of formula -CnH2n+i wherein n is 1 to 100. An alkyl may be linear or branched. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, 2-methylbutyl, 2,2- dimethylpropyl, n-hexyl, 2-methylpentyl, 2,2-dimethylbutyl, n-heptyl, 2-ethylhexyl, and the like.

[0026] The term “aliphatic compound or group” as used herein means a non-aromatic compound or group. Compounds or groups comprising a cycloaliphatic ring (i.e. a non-aromatic ring) are encompassed by the term aliphatic compound or group. It may be linear or branched, saturated orunsaturated, cyclic or acyclic. It may be substituted by one or more groups, for example selected from alkyl, hydroxyl, halogen (Br, Cl, I), isocyanate, carbonyl (=0), amine, carboxylic acid, -C(=O)-OR’, - C(=O)-O-C(=O)-R’, each R’ being independently a C1-C6 alkyl. It may comprise one or more bonds selected from ether, ester, amide, urethane, urea, carbonate, organosiloxane, and mixtures thereof.

[0027] The term “aromatic compound or group” as used herein means a compound or a group comprising at least one aromatic ring (i.e. a ring respecting Hiickel’s aromaticity rule, such as a phenyl), in particular one, two or three, preferably one or two, aromatic rings. Araliphatic compounds, groups or linkers, i.e. comprising both an aromatic moiety and a non-aromatic moiety, are encompassed by the term aromatic compound or group. It may be substituted by one or more groups as defined for the term “aliphatic compound or group”. It may comprise one or more bonds as defined for the term “aliphatic compound or group”.

[0028] The term “urethane bond” used herein means a -NH-C(=O)-O- bond.

[0029] The term “polyisocyanate” used herein means a compound comprising at least two isocyanate groups.

[0030] The term “ethylenically unsaturated compound” used herein refers to a compound comprising at least one ethylenic unsaturation, i.e., at least one carbon-carbon (C=C) double bond, in particular at least one carbon-carbon double bond capable of participating in a free radical reaction wherein at least one of the carbon atoms of the double bond becomes covalently bonded to another atom, in particular a carbon atom (C-C) or a sulfur atom (C-S), in a second molecule. Such compound may comprise several ethylenic unsaturations.

[0031] As used herein, the term “(meth)acrylate group” refers indifferently to an acrylate group or a methacrylate group.

[0032] As used herein, the term “(meth)acrylate-functionalized monomer” means a monomer comprising one or several (meth)acrylate group(s). The term “(meth)acrylate-functionalized oligomer” means an oligomer comprising one or several (meth)acrylate group(s).

[0033] In the context of the present invention, the term “organic solvent” means a solvent having carbon atoms.Curable composition

[0034] The present invention relates to a curable composition which may be efficiently cured when exposed to radiation and / or heat and presents improved performance in terms of shelf-life stability. The curable composition comprises at least two components: a polythiol component and a so-called ethylenically unsaturated component.

[0035] More precisely, the curable composition of the present invention comprises a) a polythiol comprising at least three sulfhydryl (-SH) groups, wherein the polythiol is in the form of acycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups; and b) a component comprising one or more ethylenically unsaturated compounds (also called herein “ethylenically unsaturated component”).

[0036] Curing may involve exposing the composition of the present invention to a radiation source, such as visible or UV light, infrared radiation, and / or electron beam radiation and / or by heating the composition. The radiation source is preferably visible or UV light. Such curing reactions, including polymerization reactions, may result in the incorporation of the components of the composition in a network, a matrix or a polymeric chain (all terms used interchangeably herein).

[0037] The curable composition of the present invention is characterized in that the type of ethylenically unsaturated components and weight ratio of each component in the composition may be specifically adjusted to promote distinct and / or combined curing mechanisms and / or adjust the mechanical properties of the cured composition.

[0038] In particular, the selection of the type of component comprising one or more ethylenically unsaturated compounds may be tailored to suit the desired curing method.

[0039] In some embodiments, the ethylenically unsaturated component is selected to be an “ene” component, also called interchangeably herein an electron-rich component. In the thiol-ene reaction, the sulfur atoms of the -SH groups of the polythiol react with the double bonds of the ethylenically unsaturated component, forming a new carbon-sulfur (C-S) bond and breaking the carbon-carbon (C=C) double bond. In these embodiments, the curing mechanism is predominantly based on propagation and chain transfer steps. The polymerization occurs under “step-growth” mechanism.

[0040] In some other embodiments, the ethylenically unsaturated compounds of component b) are selected to incorporate one or several polymerizable group(s) (e.g., homopolymerizable groups) and is called herein polymerizable component or electron-deficient component. In such embodiments, the ethylenically unsaturated components may react either with a carbon centered radical (obtained from the polymerization of polymerizable components) forming a new carbon-carbon (C-C) bond and / or they may react with a sulfur centered radical (obtained from the reaction of the polythiol with the double bonds of the polymerizable component) forming a new carbon-sulfur (C-S) bond, and breaking the carbon-carbon (C=C) double bonds. In these embodiments, the curing mechanism relies on both propagation and chain transfer steps, wherein propagation can occur through either step-growth mechanism or chain growth polymerization.

[0041] In such curing mechanisms, polythiols offer the advantage of circumventing oxygen inhibition, an issue occurring in polymerization processes where the presence of oxygen can hinder efficient curing.Polythiol

[0042] The curable composition of the present invention is characterized in that it comprises a polythiol a) comprising three or more sulfhydryl (-SH) groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups. With three or more sulfhydryl (-SH) groups, the polythiol used in the context of the present invention qualifies as a high functional polythiol (f > 3).

[0043] Within the framework of the present invention, the polythiol used in the curable composition of the present invention may act as a chain transfer agent in thiol-ene compositions and / or as crosslinker agent (or crosslinking agent) in polymerizable compositions. As such, the polythiol contributes to the controlled curing process while simultaneously facilitating the formation of interconnected molecular networks, thereby enhancing the overall performance and durability of the cured composition.

[0044] In some preferred embodiments, the at least three -SH groups in the polythiol a) are secondary thiol groups.

[0045] In some preferred embodiments, the at least three -SH groups are directly bonded to carbon atoms forming said cycloaliphatic ring.

[0046] In some embodiments, the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, for example between 10 and 13 carbon atoms, for example 11 or 12 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups.

[0047] In some preferred embodiments, the polythiol is derived from humulene or from cyclododecatriene, even more preferably cyclododecatriene. In particular, the polythiol is obtained from the reaction between cyclododecatriene and a sulfhydryl donor such as H2S or thioacetic acid (protected sulfhydryl group which can be then deprotected), for example as described in the document WO 2024 / 200981.

[0048] In some preferred embodiments, the polythiol is unsubstituted, e.g., it is not substituted by any C1-C4 alkyl group.

[0049] In some preferred embodiments, the polythiol a) is the cyclododecanetrithiol.

[0050] The polythiol used in the composition of the present invention may have a viscosity at 25°C of less than 2,000 mPa.s., preferably less than 1,000 mPa.s, for example ranging from 1 mPa.s to 1000 mPa.s or from 100 mPa.s to 1,000 mPa.s. The viscosity of the polythiol may be measured on a Brookfield viscometer.

[0051] The polythiol described herein may be prepared using methods that are readily available or commonly employed in the field. Reference may notably be made to the process described in GB1352527 filed by Ciba Geigy or in WO 2024 / 200981.Ethylenically unsaturated component

[0052] The curable composition of the present invention is characterized in that it comprises a component b) comprising one or more ethylenically unsaturated compounds.

[0053] Different classes of ethylenically unsaturated compounds may be used in the context of the present invention. In particular, three classes of ethylenically unsaturated compounds are defined below.

[0054] In some embodiments, the ethylenically unsaturated component b) comprises at least one compound comprising one or several polymerizable group(s) and is called herein polymerizable component or electron-deficient component. In these embodiments, the component b) may comprise at least one compound comprising an acrylate functional group ( — O-C(O)-CH=CH2), a methacrylate functional group ( — O-C(O)-C(CH3)=CH2), an acrylamide functional group ( — NH-C(O)-CH=CH2). a methacrylamide functional group ( — NH-C(O)-C(CH3)=CH2), a vinyl sulfone functional group (-SO2- CH=CH2), a maleimide functional group or mixture thereof; preferably an acrylate functional group ( — O-C(O)-CH=CH2) and / or a methacrylate functional group ( — O-C(O)-C(CH3)=CH2).

[0055] In some other embodiments, the ethylenically unsaturated component b) is an “ene” component, also called interchangeably herein electron-rich component. In these embodiments, the component b) may comprise at least one compound comprising a vinyl group ( — CH=CH2), a vinyl ether group ( — O-CH=CH2), an allyl group ( — CH2-CH=CH2), an allyl ether group ( — O-CH2- CH=CH2), or any mixtures thereof.

[0056] In some embodiments, the ethylenically unsaturated component b) comprises compounds comprising both polymerizable group(s), as well as group(s) comprising vinylic and / or allylic functions as described above. Such components may be monomers, oligomers, or mixtures thereof. Such monomers or oligomers may comprise one or several allylic groups, for example two or three allylic groups. They may comprise one or several (meth)acrylate group(s). For example, such monomer or oligomer may comprise at least two allylic groups and at least one (meth)acrylate group. Suitable examples of oligomers falling in this class of component b) are (meth)acrylated non- hydrogenated polydiene polyol oligomers (multi-(meth)acrylated), for example (meth)acrylated non-hydrogenated polydiene diol oligomers (di(meth)acrylated), bearing in the backbone (internal) cis / trans ethylenic insaturation (defined as an internal allylic insaturation). These oligomers may be based on homopolymers or copolymers of dienes, for example butadiene and / or isoprene. More specifically, a suitable example of such component b) is a polybutadiene diol di(meth)acrylate. More particularly, (meth)acrylated poly diene polyol oligomers, preferably poly diene diol oligomers, may be selected from the group consisting of (meth)acrylated polyols of poly butadiene, polyisoprene and random or block copolymers of butadiene or isoprene, preferably random or block copolymers with a comonomer selected from styrene, methylstyrene and famesene (including 3,7,ll-trimethyl-l,3,6,10- dodecatetraene and (3 7,ll-dimethyl-3-methylene-l,6,10-dodecatriene).

[0057] All combinations of ethylenically unsaturated compounds are possible within the scope of the present invention. In particular, the curable composition of the present invention may comprise a component b) comprising:- one type only of ethylenically unsaturated compounds (i.e., within a single class);- several distinct ethylenically unsaturated compounds within the same class; or- several distinct ethylenically unsaturated compounds within different classes.

[0058] In some embodiments, the component b) is at least one of a (meth)acry late -functionalized monomer, a (meth)acrylate-functionalized oligomer, or mixtures thereof.

[0059] The component b) may comprise one (meth)acrylate-functionalized monomer or a mixture of (meth)acry late-functionalized monomers.

[0060] A (meth)acrylate-functionalized monomer may have a molecular weight of less than 600 g / mol, in particular from 100 to 550 g / mol, more particularly from 200 to 500 g / mol.

[0061] A (meth)acry late -functionalized monomer may have 1 to 6 (meth)acrylate groups, in particular 1 to 3 (meth)acrylate groups.

[0062] The component b) may comprise one mono(meth)acrylate-functionalized monomer or a mixture of (meth)acrylate-functionalized monomers, for example having different functionalities. For example, the component b) may comprise a mixture of a (meth)acrylate-functionalized monomer containing a single acrylate or methacrylate group per molecule (referred to herein as “mono(meth)acrylate-functionalized compounds”) and a (meth)acry late -functionalized monomer containing 2 or more, preferably 2 or 3, acrylate and / or methacrylate groups per molecule (referred to herein as “poly(meth)acrylate-functionalized compounds”).

[0063] Examples of suitable mono(meth)acrylate-functionalized monomers include, but are not limited to, mono-(meth)acrylate esters of aliphatic alcohols (wherein the aliphatic alcohol may be straight chain, branched or alicyclic and may be a mono-alcohol, a di-alcohol or a poly alcohol, provided only one hydroxyl group is esterified with (meth)acrylic acid); mono-(meth)acrylate esters of aromatic alcohols (such as phenols, including alkylated phenols); mono-(meth)acrylate esters of alkylaryl alcohols (such as benzyl alcohol); mono-(meth)acrylate esters of oligomeric and polymeric glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol); mono-(meth)acrylate esters of monoalkyl ethers of glycols and oligoglycols; mono-(meth)acrylate esters of alkoxylated (e.g., ethoxylated and / or propoxylated) aliphatic alcohols (wherein the aliphatic alcohol may be straight chain, branched or alicyclic and may be a mono-alcohol, a di-alcohol or a polyalcohol, provided only one hydroxyl group of the alkoxylated aliphatic alcohol is esterified with (meth)acrylic acid); mono-(meth)acrylate esters of alkoxylated (e.g., ethoxylated and / or propoxylated) aromatic alcohols (such as alkoxylated phenols); caprolactone mono(meth)acrylates; and the like.

[0064] The following compounds are specific examples of mono(meth)acrylate-functionalized monomers suitable for use in component b): methyl (meth)acrylate; ethyl (meth)acrylate; n-propyl (meth)acrylate; n-butyl (meth) aery late; isobutyl (meth)acrylate; n-hexyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; n-octyl (meth)acrylate; isooctyl (meth)acrylate; n-decyl (meth)acrylate; n-dodecyl (meth)acrylate; tridecyl (meth)acrylate; tetradecyl (meth)acrylate; hexadecyl (meth)acrylate; 2- hydroxyethyl (meth)acrylate; 2- and 3-hydroxypropyl (meth)acrylate; 2-methoxyethyl (meth)acrylate; 2 -ethoxyethyl (meth)acrylate; 2- and 3-ethoxypropyl (meth)acrylate; tetrahydrofurfuryl (meth)acrylate; alkoxylated tetrahydrofurfuryl (meth)acrylate; 2-(2-ethoxyethoxy)ethyl (meth)acrylate; cyclohexyl (meth)acrylate; glycidyl (meth)acrylate; isodecyl (meth) aery late; lauryl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; alkoxylated phenol (meth)acrylates; alkoxylated nonylphenol (meth)acrylates; cyclic trimethylolpropane formal (meth)acrylate; isobornyl (meth) acrylate; tricyclodecanemethanol (meth)acrylate; tert-butylcyclohexanol (meth)acrylate; trimethylcyclohexanol (meth)acrylate; diethylene glycol monomethyl ether (meth)acrylate; diethylene glycol monoethyl ether (meth)acrylate; diethylene glycol monobutyl ether (meth)acrylate; triethylene glycol monoethyl ether (meth)acrylate; ethoxylated lauryl (meth)acrylate; methoxy polyethylene glycol (meth)acrylates; hydroxyl ethyl-butyl urethane (meth)acrylates; 3-(2-hydroxyalkyl)oxazolidinone (meth)acrylates; and combinations thereof.

[0065] The component b) may comprise a poly(meth)acry late-functionalized monomer.

[0066] A poly(meth)acrylate-functionalized monomer may have from 2 to 6 (meth)acrylate groups, in particular from 2 to 6 acrylate groups.

[0067] Examples of suitable poly(meth)acrylate-functionalized monomers include acrylate and methacrylate esters of polyols. Examples of suitable polyols are aliphatic polyol optionally substituted with one or more groups selected from alkyl, cycloalkyl, and a halogen atom, as well as optionally substituted aromatic polyol. Such polyols may be fully or partially esterified (with (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride or the like), provided they contain at least two (meth)acrylate functional groups per molecule.

[0068] Exemplary poly(meth)acrylate-functionalized monomers may include bisphenol A di(meth)acrylate; hydrogenated bisphenol A di(meth)acrylate; ethylene glycol di(meth)acrylate; diethylene glycol di(meth)acrylate; triethylene glycol di(meth)acrylate; tetraethylene glycol di(meth)acrylate; polyethylene glycol di(meth)acrylate; propylene glycol di(meth)acrylate; dipropylene glycol di(meth)acrylate; tripropylene glycol di(meth)acrylate; tetrapropylene glycol di(meth)acrylate; polypropylene glycol di(meth)acrylate; polytetramethylene glycol di(meth)acrylate; 1,2 -butane diol di(meth)acrylate; 2,3 -butanediol di(meth)acrylate; 1,3-butanediol di(meth)acrylate; 1,4-butanediol di(meth)acrylate; 1,5 -pentanediol di(meth)acrylate; 1,6-hexanediol di(meth)acrylate; 1 ,8-octanediol di(meth)acrylate; 1,9 -nonane diol di(meth)acrylate; 1,10-nonanediol di(meth)acrylate; 1,12- dodecanediol di(meth)acrylate; neopentyl glycol di(meth)acrylate; 2-methyl-2,4-pentanediol di(meth)acrylate; polybutadiene di(meth)acrylate; cyclohexane-l,4-dimethanol di(meth)acrylate;tricyclodecane dimethanol di(meth)acrylate; metallic di(meth)acrylates; modified metallic di(meth)acrylates; glyceryl di(meth)acrylate; glyceryl tri(meth)acrylate; trimethylolethane tri(meth)acrylate; trimethylolethane di(meth)acrylate; trimethylolpropane tri(meth)acrylate; trimethylolpropane di(meth)acrylate; pentaerythritol di(meth)acrylate; pentaerythritol tri(meth)acrylate; pentaerythritol tetra(meth)acrylate, di(trimethylolpropane) diacrylate; di(trimethylolpropane) triacrylate; di(trimethylolpropane) tetraacrylate; sorbitol penta(meth)acrylate; di(pentaerythritol) tetraacrylate; di(pentaerythritol) pentaacrylate; di(pentaerythritol) hexa(meth)acrylate; tris (2-hydroxyethyl) isocyanurate tri(meth)acrylate; as well as the alkoxylated (e.g., ethoxylated and / or propoxy lated) derivatives thereof; and combinations thereof.

[0069] The component b) may comprise from 0 to 100 wt.%, in particular from 5 to 98 wt.%, more particularly from 10 to 95 wt.%, even more particularly from 15 to 90 wt.%, more particularly still from 20 to 85 wt.% of (meth)acry late-functionalized monomer, relative to the total weight of the component b). In some embodiments, the component b) may comprise from 50 to 100 wt.% or from 55 to 99.5 wt.% or 60 to 99 wt.% or 65 to 98.5 wt.% or 70 to 98 wt.% of (meth)acry late -functionalized monomer, relative to the total weight of the component b). In some other embodiments, the component b) may comprise from 20 to 60 wt.% or from 25 to 55 wt.% or 30 to 50 wt.% or 32 to 48 wt.% or 35 to 45 wt.% of (meth)acry late-functionalized monomer, relative to the total weight of the component b).

[0070] The component b) may comprise one (meth)acry late-functionalized oligomer or a mixture of(meth)acry late -functionalized oligomers .

[0071] A (meth)acrylate functionalized oligomer may have 1 to 18 (meth) aery late groups, in particular 2 to 6 (meth)acrylate groups, more particularly 2 to 6 acrylate groups.

[0072] A (meth)acrylate functionalized oligomer may have a number average molecular weight equal or more than 600 g / mol, in particular 800 to 15,000 g / mol, more particularly 1,000 to 5,000 g / mol.

[0073] In particular, the component b) may comprise a (meth)acrylate-functionalized oligomer selected from the group consisting of epoxy (meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates (including aliphatic urethane acrylates), (meth)acrylated poly(meth)acrylates and mixtures thereof; preferably, epoxy (meth)acrylates, urethane (meth)acrylates and mixtures thereof.

[0074] Non-limiting examples of epoxy (meth)acrylates are the reaction products of an epoxide (such as glycidyl ethers, glycidyl esters, cycloaliphatic epoxides or epoxides obtained by epoxidation of mono- and / or polyunsaturated compounds) with a (meth)acrylating agent (such as (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride or combinations thereof). The epoxide may be an epoxide selected from 1,2,3,4-diepoxybutane; 1,2,4,5-diepoxypentane; 1,2,5,6-diepoxyhexane; 1, 2,7,8- diepoxy octane; 1,2, 9, 10-diepoxy decane; bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol Fdiglycidyl ether, brominated bisphenol S diglycidyl ether, epoxy novolak resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, 2-(3,4-epoxycyclohexyl-5,5- spiro-3,4-epoxy)cyclohexane-l,4-dioxane, bis(3,4-epoxycyclohexylmethyl)adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate,3,4-epoxy-6- methylcyclohexy l-3',4'-epoxy-6'-methylcyclohexanecarboxylate, methylenebis(3,4- epoxycyclohexane), dicyclopentadiene diepoxide, di(3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylenebis(3, 4-epoxycyclohexanecarboxylate), ethylene glycol diglycidyl ether, 1,2- or 1,3- propylene glycol diglycidyl ether, 1,2-, 1,3- or 1,4-butanediol diglycidyl ether, 1,5 -pentanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,7-hexanediol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,9-nonanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, 1,12-dodecanediol diglycidyl ether, 2-methyl- 1,3 -propanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 2,2- diethyl-l,3-propane diol diglycidyl ether, 3 -methyl- 1,5 -pentanediol diglycidyl ether, 3, 3 -dimethyl- 1,5- pentanediol diglycidyl ether, 2,4-diethyl-l,5-pentanediol diglycidyl ether, 3,3-butylethyl-l,5-pentane diol diglycidyl ether, di-, tri- or tetra(ethylene glycol) glycidyl ether, di-, tri- or tetra(l,2-propylene glycol) diglycidyl ether, di-, tri- or tetra( 1,3 -propylene glycol) diglycidyl ether, di-, tri- or tetra(l,4- butylene glycol) diglycidyl ether, a polyethylene glycol) diglycidyl ether, a polypropylene glycol) diglycidyl ether, a poly(trimethylene glycol) diglycidyl ether, a poly(tetramethylene glycol) diglycidyl ether, a polyethylene glycol-co-propylene glycol) diglycidyl ether, glycerol triglycidyl ether, a polyglycerol polyglycidyl ether, trimethylolmethane triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, di(trimethylolpropane) tetraglycidyl ether, pentaerythritol tetraglycidyl ether, diglycidyl cyclohexanedicarboxylate, cyclohexane diglycidyl ether, cyclohexane- 1,4-dimethanol diglycidyl ether, tricyclodecane dimethanol diglycidyl ether, isosorbide diglycidyl ether, pyrocatechol diglycidyl ether, resorcinol diglycidyl ether, cardol diglycidyl ether, phloroglucinol triglycidyl ether, pyrogallol triglycidyl ether, tris(hydroxyphenyl)methane triglycidyl ether, tris(hydroxyphenyl)ethane triglycidyl ether, diglycidyl phthalate, diglycidyl terephthalate, diglycidyl isophthalate, polyglycidyl ethers of a polyether polyol obtained by the addition of one or more alkylene oxides to an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol, and glycerol, diglycidyl esters of aliphatic long-chain (C6-C22) dibasic acids, monoglycidyl ethers of aliphatic higher alcohols, monoglycidyl ethers of phenol, cresol, butyl phenol, or polyether alcohols obtained by the addition of alkylene oxide to these compounds, glycidyl esters of higher fatty acids, an epoxidized vegetable oil (such as epoxidized soybean oil and epoxidized linseed oil), epoxybutylstearic acid, epoxyoctylstearic acid, epoxidized polybutadiene, triglycidyl isocyanurate and the like.

[0075] Non-limiting examples of polyester (meth)acrylates are the reaction products of a hydroxyl group-terminated polyester polyol with a (meth)acrylating agent (such as (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride or combinations thereof). The reaction process maybe conducted such that a significant concentration of residual hydroxyl groups remain in the polyester (meth)acrylate or may be conducted such that all or essentially all of the hydroxyl groups of the polyester polyol have been (meth)acrylated. The polyester polyols can be made by polycondensation reactions of a polyhydroxyl functional component (in particular a diol) and a poly carboxy lie acid functional compound (in particular, a dicarboxylic acid or anhydride). To prepare the polyester (meth)acrylates, the hydroxyl groups of the polyester polyol are then partially or fully esterified by reacting with the (meth)acrylating agent. Polyester (meth)acrylates may also be synthesized by reacting a hydroxyl-containing (meth)acrylate such as a hydroxyalkyl (meth)acrylate (e.g., hydroxyethyl acrylate) with a polycarboxylic acid. The polyhydroxyl functional and polycarboxylic acid functional components can each have linear, branched, cycloaliphatic or aromatic structures and can be used individually or as mixtures.

[0076] Non-limiting examples of poly ether (meth) acrylates are the condensation reaction products of a polyetherol which is a polyether polyol with a (meth)acrylating agent (such as (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride or combinations thereof). Suitable polyetherols can be linear or branched substances containing ether bonds and terminal hydroxyl groups. Polyetherols can be prepared by ring opening polymerization of epoxides and other oxygen-containing heterocyclic compounds (e.g., ethylene oxide, 1,2-propylene oxide, butene oxide, tetrahydrofuran and combinations thereof) with a starter molecule. Suitable starter molecules include water, hydroxyl functional materials, polyester polyols and amines. Polyetherols may also be obtained by the condensation of diols such as glycols.

[0077] Non-limiting examples of urethane (meth)acrylates are the condensation reaction products of at least one polyisocyanate (e.g., diisocyanate, triisocyanate), at least one polyol (such as a polyether polyol or a polyester polyol) and a hydroxyl-functionalized (meth)acrylate (such as 2-hydroxyethyl (meth)acrylate or 3 -hydroxy propyl (meth)acrylate) to provide terminal (meth)acrylate groups. For example, the urethane (meth)acrylate may contain two, three, four or more (meth)acrylate groups per molecule. The order of addition of the components to prepare the urethane (meth)acrylate is well known in the art. For example, the hydroxyl-functionalized (meth)acrylate may first reacted with the polyisocyanate to obtain an isocyanate-functionalized (meth)acrylate, which is then reacted with the polyol. In yet another embodiment, the polyisocyanate may be first reacted with the polyol to obtain an isocyanate-functionalized polyol, which is thereafter reacted with a hydroxyl-functionalized (meth)acrylate. Alternatively, all the components may be combined and reacted at the same time.

[0078] Examples of suitable polyisocyanates include 2,2,4-trimethylhexamethylene-l,6- diisocyanate, hexamethylene-l,6-diisocyanate (HDI), cyclohexyl- 1,3 -diisocyanate, cyclohexyl-1,4- diisocyanate, 2,4-diisocyanato-l -methylcyclohexane, 2,6-diisocyanato-l-methylcyclohexane 4,4'- methylene-bis(cyclohexyl isocyanate), l,l'-methylenebis(4-isocyanato)cyclohexane, isophorone diisocyanate, norbornane diisocyanate 1,4-tetramethylene diisocyanate, 1,5 -pentamethylenediisocyanate, 1,12-dodecane diisocyanate, meta- and para-xylylene diisocyanate, meta- and paratetramethylxylylene diisocyanate, 1,4-phenylene diisocyanate, 2,6- and 2,4-toluene diisocyanate, 1,5- naphthylene diisocyanate, 2,4' and 4,4'-diphenylmethane diisocyanate, and mixtures thereof.

[0079] Any (meth)acrylate type endcap having a terminal hydroxyl group and an acrylic or methacrylic moiety can be used to prepare urethane (meth) acrylates. Examples of suitable hydroxylfunctionalized (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3 -hydroxy propyl (meth)acrylate, caprolactone mono(meth)acrylate, glycerol di(meth)acrylate and / or trimethylolpropane di(meth)acrylate. Particularly preferred are 2-hydroxyethyl methacrylate (HEMA) and / or 2-hydroxyethyl acrylate (HEA).

[0080] Non-limiting examples of (meth)acrylated poly(meth)acrylates are substances having an oligomeric (meth)acrylic backbone which is functionalized with one or more (meth)acrylate group(s) (which may be at a terminus of the oligomer or pendant to the acrylic backbone). The (meth)acrylic backbone may be a homopolymer, random copolymer or block copolymer comprised of repeating units of (meth)acrylic monomers. The (meth)acrylic monomers may be any monomeric (meth)acrylate such as C1-C6 alkyl (meth)acrylates as well as functionalized (meth)acrylates such as (meth)acrylates bearing hydroxyl, carboxylic acid and / or epoxy groups. Meth)acrylated poly(meth)acrylates may be prepared using any procedures known in the art, such as by oligomerizing (meth)acrylic monomers, at least a portion of which are functionalized with hydroxyl, carboxylic acid and / or epoxy groups (e.g., hydroxyalkyl(meth)acrylates, (meth)acrylic acid, glycidyl (meth)acrylate) to obtain a functionalized poly(meth)acrylate, which is then reacted with one or more (meth)acrylate-containing reactants to introduce the desired (meth)acrylate functional groups.

[0081] The component b) may comprise from 1 to 100 wt.%, in particular from 5 to 90 wt.%, more particularly from 10 to 80 wt.%, even more particularly from 15 to 70 wt.%, more particularly still from 16 to 65 wt.% of (meth)acry late -functionalized oligomer, relative to the total weight of the component b). In particular, the component b) may comprise from 0.1 to 70 wt.%, from 1.5 to 68 wt.%, from 5 to 65 wt.%, from 9 to 63 wt.% or 11 to 61 wt.% of (meth)acrylate-functionalized oligomer, relative to the total weight of the component b).

[0082] In some preferred embodiments, the component b) is a mixture of at least one (meth)acry late- functionalized monomer and at least one (meth)acry late -functionalized oligomer. In some examples, the component b) may comprise at least one mono(meth)acry late -functionalized monomer and at least one urethane (meth)acrylate (including aliphatic urethane acrylate). In some other examples, the component b) may alternatively comprise at least one poly(meth)acry late-functionalized monomer (for example one or two poly(meth)acrylate-functionalized monomer(s)) and at least one urethane (meth)acrylate (including aliphatic urethane acrylate).

[0083] In some embodiments, the component b) may comprise one or more of the following ethylenically unsaturated compounds:poly vinylic and / or poly ally lie monomers (in particular divinyl benzene, 1,4-butanediol divinyl ether, tri(ethylene glycol) divinyl ether, diallyl ether, glycerol diallyl ether, glycerol triallyl ether, trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, diallyl phthalate, triallyl isocyanurate, 2,4,6-triallyloxy- 1,3,5-triazine, glyoxal bis(dially 1 acetal) and mixtures thereof); vinyl esters of carboxylic acids (in particular vinyl acetate, vinyl propionate, vinyl hexanoate, vinyl 2-ethylhexanoate, vinyl octanoate, vinyl pelargonate, vinyl laurate, vinyl stearate, a vinyl ester of versatic acid and mixtures thereof); vinyl ethers (in particular vinyl methyl ether, vinyl ethyl ether, vinyl n-butyl ether, vinyl isobutyl ether and mixtures thereof, ethylene glycol divinyl ether, triethylene glycol divinyl ether and trimethylolpropane trivinyl ether); cycloaliphatic vinyl monomers (in particular vinylcyclohexane); olefins (in particular ethylene, propene, 1-butene, isobutylene, diisobutylene, 1-nonene, 1- decene and mixtures thereof); conjugated dienes (in particular butadiene, isoprene, pentadiene, chlorodiene and mixtures thereof); vinyl aromatic monomers (in particular styrene, alpha-methylstyrene, tert-butylstyrene, ortho-, meta-, and para-methylstyrene, ortho-, meta- and para-ethylstyrene, o-methyl-p- isopropylstyrene, p-chlorostyrene, p-bromostyrene, o,p-dichlorostyrene, o,p-dibromostyrene, ortho-, meta- and para-methoxy styrene, optionally substituted indenes, optionally substituted vinylnaphthalenes, acenaphthylene, diphenylethylene, vinyl anthracene and mixtures thereof); mono- or dicarboxylic acid monomers, cyclic anhydride monomers and salts thereof (in particular 3-butenoic acid, crotonic acid, vinyl acetic acid, fumaric acid, maleic acid, maleic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, itaconic acid, mesaconic acid, citraconic acid, glutaconic acid, muconic acid and mixtures thereof); unsaturated polymers such as poly butadiene; as well as the alkoxylated (e.g., ethoxylated and / or propoxylated) derivatives thereof; and mixtures thereof.In addition to component (b), the curable composition may comprise other polymerizable compound(s) (e.g., independently polymerizable). In a specific embodiment, the curable composition does not substantially comprise epoxy-containing compounds; more particularly, the curable composition does not comprise epoxy-containing compound(s).Weight and molar ratios

[0084] Various weight and molar ratios of polythiol can be employed in the composition of the present invention, depending on the nature and function of the ethylenically unsaturated component b) and the curing mechanism.

[0085] In embodiments where the component b) is an electron-deficient component (i.e., wherein b) may comprise at least one compound comprising an acrylate functional group, a methacrylate functional group, an acrylamide functional group, a methacrylamide functional group, a vinyl sulfone functional group (-SO2-CH=CH2), a maleimide functional group or mixture thereof), the composition may comprise between 0.1 and 50 wt.% of polythiol a), relative to the total weight of the composition, preferably between 0.2 and 40 wt.%, between 0.3 and 30 wt.%, between 0.4 and 20 wt.% and more preferably between 0.1 and 10 wt.%.

[0086] In embodiments where the component b) is an electron-rich component (i.e., wherein b) may comprise at least one compound comprising a vinyl group, a vinyl ether group, an allyl group, an allyl ether group, or any mixtures thereof), the composition may comprise 0.5 to 10 molar equivalent of -SH groups per double bond, for example 1 to 8 molar equivalent of 2 to 6 molar equivalent of -SH groups per double bond.Inhibitor

[0087] The curable composition of the invention may comprise an inhibitor. The curable composition may comprise one or more inhibitor(s).

[0088] The composition may comprise from 10 ppm to 5 wt.% of one or more inhibitors, for example from 20 ppm to 4 wt.%, from 50 ppm to 3 wt.%, from 100 ppm to 1 wt.%, or from 120 ppm to 0.1 wt.%, relative to the total weight of the curable composition.

[0089] Inhibitors may be introduced in the curable composition in order to provide adequate storage stability and shelf life. As described above, an inhibitor may typically retard or prevent reaction or curing of functional groups present in a composition, notably in the absence of radiation.

[0090] Any of the inhibitors known in the art related to ethylenically unsaturated compounds may be utilized in the composition of the invention. Quinones represent a particularly preferred type of inhibitor which can be employed in the context of the present invention. As used herein, the term "quinone" includes both quinones and hydroquinones as well as ethers thereof such as monoalkyl, monoaryl, monoaralkyl and bis(hydroxyalkyl) ethers of hydroquinones. Hydroquinone monomethyl ether is an example of a suitable inhibitor which can be utilized. Other inhibitors known in the art include as hydroquinone (HQ), 4-methoxyphenol (MEHQ), 4-tert-butylcatechol (TBC), 3,5-di- tertiobutyl-4-hydroxytoluene (BHT), phenothiazine (PTZ), pyrogallol, phosphite compounds, triphenyl antimony and tin(II) salts.Initiator

[0091] The curable composition may comprise an initiator, for example an initiator selected from a free radical initiator, and combinations thereof. The curable composition may comprise one or more initiator(s). The curable composition may comprise a mixture of a free radical initiator and a cationic initiator.

[0092] Alternatively, the curable composition may be free from initiator, or may comprise an amount of initiator which is less than 1 wt.%, relative to the total weight of the curable composition. According to such embodiments, the amount of initiator(s) in the composition may be less than 0.8 wt.%, less than 0.6 wt.%, less than 0.4 wt.%, less than 0.2 wt.%, less than 0.1 wt.%, or even less than 0.01 wt.%, relative to the total weight of the curable composition.

[0093] In embodiments where the composition comprises one or several initiators, the total amount of initiator(s) may be varied as may be appropriate depending on the initiator(s) selected, the amounts and types of component b) present in the curable composition, the radiation source and the radiation conditions used, among other factors. Typically, however, the total amount of initiator(s) may be from 0 to 10 wt.%, in particular from 0.1 to 9 wt.%, more particularly from 0.5 to 8 wt.%, even more particularly from 1 to 6 wt.%, relative to the total weight of the curable composition. For example, the total amount of initiator(s) may be from 0 to 5 wt.%, from 0.02 to 3 wt.%, from 0.05 to 2 wt.%, from 0.1 to 1.5 wt.% or from 0.2 to 1 wt.%, relative to the total weight of the curable composition. In another example, the amount of photoinitiator(s) may be from 1 to 5 wt.%, from 1.5 to 5 wt.%, from 2 to 5 wt.%, from 2.5 to 5 wt.% or from 3 to 5 wt.%, relative to the total weight of the curable composition.

[0094] Initiators are generally divided into two classes, depending on their mode of action: free radical initiators and cationic initiators.

[0095] Free radical initiators encompass both photoinitiators and thermal initiators.

[0096] Photoinitiators are compounds that can generate free radicals upon exposure to light of an appropriate wavelength and / or intensity. Photoinitiators can adopt two different modes of action, and are classified by mode of action as Norrish Type I and Norrish Type II photoinitiators. As used herein, the term “activity” with reference to Norrish Type I and Norrish Type II activity is intended to relate to Norrish photoinitiation and analogous reactions. For instance, a photoinitiator having Norrish Type I activity within the scope of this invention would be a photoinitiator characterized by a cleavage reaction into two radical fragments of the original photoinitiator on exposure to light. For an initiator having Norrish Type II activity, exposure to light causes the abstraction of an atom, such as hydrogen, to generate the radical.

[0097] Thermal initiators are compounds that can generate free radicals upon exposure to heat and / or in the presence of a reducing agent or a base.

[0098] Cationic initiators are often salts, for instance iodonium and sulfonium salts. When these salts are activated (i.e., by irradiation with actinic radiation such as light), they undergo homolytic bond cleavage forming radicals that react with a proton donor to give a Bronsted or Lewis acid. The generated acid then initiates the polymerization.

[0099] The curable composition may comprise a free radical initiator which is a photoinitiator, in particular a photoinitiator having Norrish type I activity and / or Norrish type II activity, more particularly a free radical initiator having Norrish type I activity.

[0100] Non-limiting types of photoinitiators suitable for use in the curable compositions of the present invention include, for example, benzoins, benzoin ethers, acetophenones, a-hydroxy acetophenones, benzyl, benzyl ketals, anthraquinones, phosphine oxides, acylphosphine oxides, a- hydroxyketones, phenylglyoxylates, a-aminoketones, benzophenones, thioxanthones, xanthones, acridine derivatives, phenazene derivatives, quinoxaline derivatives, triazine compounds, benzoyl formates, aromatic oximes, metallocenes, acylsilyl or acylgermanyl compounds, camphorquinones, polymeric derivatives thereof, and mixtures thereof.

[0101] Examples of suitable photoinitiators include, but are not limited to, 2-methylanthraquinone, 2-ethylanthraquinone, 2 -chloroanthraquinone, 2-benzyanthraquinone, 2-t-butylanthraquinone, 1,2- benzo-9,10-anthraquinone, benzyl, benzoins, benzoin ethers, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, alpha-methylbenzoin, alpha-phenylbenzoin, Michler’s ketone, acetophenones such as 2,2-dialkoxybenzophenones and 1-hydroxyphenyl ketones, benzophenone, 4,4’- bis-(diethylamino) benzophenone, acetophenone, 2,2-diethyloxyacetophenone, diethyloxyacetophenone, 2-isopropylthioxanthone, thioxanthone, diethyl thioxanthone, 1,5- acetonaphthylene, benzil ketone, a-hydroxy keto, 2,4,6-trimethylbenzoyldiphenyl phosphine oxide, benzyl dimethyl ketal, 2,2-dimethoxy-l,2-diphenylethanone, 1 -hydroxy cylclohexyl phenyl ketone, 2- methy 1-1 -[4-(methylthio) phenyl] -2-morpholinopropanone-l , 2-hydroxy-2-methyl-l -phenylpropanone, oligomeric a-hydroxy ketone, benzoyl phosphine oxides, phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenyl phosphinate, anisoin, anthraquinone, anthraquinone-2-sulfonic acid, sodium salt monohydrate, (benzene) tricarbonylchromium, benzil, benzoin isobutyl ether, benzophenone / l-hydroxycyclohexyl phenyl ketone, 50 / 50 blend, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4-benzoylbiphenyl, 2-benzyl- 2-(dimethylamino)-4'-morpholinobutyrophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'- bis(dimethylamino)benzophenone, camphorquinone, 2-chlorothioxanthen-9-one, dibenzosuberenone, 4,4'-dihydroxybenzophenone, 2,2-dimethoxy-2-phenylacetophenone, 4-(dimethylamino)benzophenone, 4,4'-dimethylbenzil, 2,5-dimethylbenzophenone, 3,4- dimethylbenzophenone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide / 2-hydroxy-2- methylpropiophenone, 50 / 50 blend, 4'-ethoxyacetophenone, 2,4,6-trimethylbenzoyldiphenylphophine oxide, phenyl bis(2,4,6-trimethyl benzoyl)phosphine oxide, ferrocene, 3'-hydroxyacetophenone, 4'-hydroxyacetophenone, 3-hydroxybenzophenone, 4-hydroxybenzophenone, 1 -hydroxy cyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-methylbenzophenone, 3-methylbenzophenone, methybenzoylformate, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, phenanthrene quinone, 4'-phenoxyacetophenone, (cumene)cyclopentadienyl iron(ii) hexafluorophosphate, 9,10-diethoxy and 9,10-dibutoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, thioxanthen-9-one and combinations thereof.

[0102] In particular, the photoinitiator may comprise a photoinitiator selected from a benzophenone such as SpeedCure® BP (benzophenone), SpeedCure® 7005 (polymeric benzophenone), SpeedCure® 7006 (polymeric benzophenone), SpeedCure® EMK (4,4’-bis(diethylamino)benzophenone) or SpeedCure® BMS (4-benzoyl-4’ -methyldiphenyl sulphide); a thioxanthone such as SpeedCure® 7010 (polymeric thioxanthone), SpeedCure® ITX (isopropyl thioxanthone), SpeedCure® DETX (2,4- diethylthioxanthone) or SpeedCure® CPTX (l-chloro-4-propoxythioxanthone); an a-hydroxy acetophenone; an acylphosphine oxide such as SpeedCure® BPO (phenyl bis(2,4,6-trimethylbenzoyl)- phosphine oxide), SpeedCure® TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide) or SpeedCure® TPO-L (ethyl (2,4,6-trimethylbenzoyl)phenyl phosphinate); a phenylglyoxylate such as SpeedCure® MBF (methylbenzoylformate); and mixtures thereof.

[0103] The curable composition may comprise a free radical initiator which is a thermal initiator.

[0104] Thermal initiators are well known in the art and include, for example, peroxides (i.e., a compound comprising an oxygen-oxygen single bond), especially inorganic persulfate compounds such as ammonium persulfate, potassium persulfate and sodium persulfate; hydrogen peroxide; organic peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide; peracids such as peracetic acid and perbenzoic acid; redox initiators wherein a reducing agent such as a ferrous compound promotes the decomposition of a peroxide; as well as other free radical producing materials such as an azo-initiator (i.e., a compound comprising an nitrogennitrogen double bond), for example 2,2'-azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid) or 2,2’- azobis(2-methylbutyronitrile); and combinations thereof.

[0105] When utilizing an initiator to initiate photopolymerization (curing), it is generally advisable to employ a wavelength that corresponds to the absorption wavelength of the initiator. A high pressure mercury lamp, a medium pressure mercury lamp, an excimer lamp, a low pressure mercury lamp or an LED light source can be used for this purpose.Solvent(s) / Diluent(s)

[0106] The curable composition may comprise a solvent or a diluent (used interchangeably herein). The curable composition may comprise one or more non-reactive solvent(s), for example organic solvent(s), and / or non-reactive diluent(s).

[0107] Suitable organic solvents include, but are not limited to, primary and secondary alcohols such as methanol, ethanol, propanol, isopropanol, and other organic solvents such as ethyl acetate, dioxane, methyl acetate, acetone, tert-butyl methyl ether, D-limonene, terpineol, geraniol, acetonitrile, dichloromethane, chloroform, chlorobenzene, difluorobenzene, tetrahydrofuran, dimethyl sulfoxide, dimethyl formamide.

[0108] Advantageously, the curable composition of the present invention may be formulated to be solvent-free. For example, the curable composition of the present invention may contain little or no solvent, e.g., less than 10 %, or less than 5 %, or less than 1 %, or even 0 % by weight of solvent, based on the total weight of the curable composition.Additives (e.g., fillers, elastomers)

[0109] The curable compositions of the present invention may comprise one or more additives selected from the group consisting of antioxidants, ultraviolet absorbers, stabilizers, foam inhibitors, flow or leveling agents, colorants, dyes, pigments, dispersants (wetting agents), slip additives, fillers, elastomers, tougheners, thixotropic agents, matting agents, waxes, any additive conventionally utilized in coating, sealant, adhesive, ink or molding compositions, and combinations thereof.

[0110] In some embodiments, the curable compositions of the invention comprise one or more fillers. Examples of fillers include glass particles, quartz, graphite powder, carbon black, aluminum oxide powder and silica.

[0111] In some embodiments, the curable compositions of the invention comprise one or more elastomers. Examples of elastomers include RTV rubber and silicone rubber.

[0112] In some embodiments, the curable compositions of the invention comprise one or more stabilizer (also called herein “stabilizing agent”), for example a free radical scavenger selected from hindered phenolic or hindered amine compounds. The stabilizer can be C1-C4 di-substituted phenols in alpha position vs OH or hindered cyclic amines having double substitution by C1-C4 alkyls in alpha position from the amine in the cycle, as HALS amines (Hindered amine light stabilizers) like 2, 2,6,6- tetramethyl piperidine derivatives.Viscosity of the composition

[0113] The composition of the present invention may have a viscosity at 25°C ranging from lOO mPa.s to 500,000 mPa.s. The viscosity of the compositions may be measured on a Brookfield viscometer.

[0114] In some embodiments, the curable compositions have a viscosity at 25 °C ranging from 100 mPa.s to 500,000 mPa.s, for example from 1,000 mPa.s to 300,000 mPa.s.End-use applications

[0115] The curable compositions of the invention are useful for an adhesive, an ink, a 3D printing material, a sealant, a coating, a photosensible material, or a composite.

[0116] The present invention is therefore directed to the use of the curable composition described herein (or to a method of using the curable composition described herein) for an adhesive, an ink, a 3D printing material, a sealant, a coating, a photosensible material or a composite.

[0117] Such use of the curable composition described herein (or the method of using the curable composition described herein) is particularly adapted in the dental, optic, electronics, automotive and construction fields.

[0118] Cured compositions may be especially useful for, among others, dental resins or composites, outdoor (coating) materials, in housings for electronic products, microelectronics, optical materials, home electric appliances and precision apparatuses such as cameras and watches or for adhesive and sealant materials especially in automotive, aerospace / aircraft and construction.Method of making a cured composition

[0119] The method of making a cured composition of the invention comprises curing the curable composition as described herein. The cured composition presents mechanical performances which are well-suited for many applications as listed herein.

[0120] Curing may be accelerated or facilitated by supplying energy to the composition, such as by exposing the composition to a radiation source, such as visible or UV light, infrared radiation, and / or electron beam radiation and / or by heating the composition. The cured composition is the reaction product obtained from curing the curable composition described herein.

[0121] In some embodiments, the method of making a cured composition comprises exposing the curable composition to ultraviolet light (UV) radiation, electron beam (EB) radiation and / or heat. Combination of UV and heat may be used for dual systems.

[0122] The curable compositions of the present invention are particularly well suited to being cured using LED (Light Emitting Diode) curing, e.g., UV LED curing, using radiation from a UV LED device, as well as heat, e.g., temperatures ranging from 30 to 200 °C.

[0123] In particular, thermal curing may take place at temperatures ranging from 15°C to 200°C. The temperatures selected for thermal curing may notably depend on the type of curing agents which may be used in the compositions to be cured. In some embodiments, the thermal curing is carried out at a temperature ranging from 50°C to 100°C, for example ranging from 60°C to 95°C. In some other embodiments, the thermal curing is carried out at a temperature ranging from 100°C to 150°C, for example ranging from 110°C to 145°C. In some other embodiments yet, the thermal curing is carried out at a temperature ranging from 150°C to 200°C, for example ranging from 155°C to 195°C.

[0124] When utilizing an initiator to initiate photopolymerization (curing), it is generally advisable to employ a wavelength that corresponds to the absorption wavelength of the initiator. A high-pressure mercury lamp, a medium pressure mercury lamp, a low-pressure mercury lamp, an excimer lamp or an LED light source can be used for this purpose.Cured composition

[0125] The present invention also relates to a cured composition or finished cured product, which results from the cure of the curable composition described herein.

[0126] More particularly, the cured composition or finished cured product may be selected from the group consisting of coatings, inks, adhesives, and varnishes.

[0127] The cured composition or finished cured product may typically be obtained by curing the curable composition described herein.Polythiol and various uses

[0128] The present invention also relates to the use of a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups, preferably the cyclododecanetrithiol, in combination with a component comprising one or more ethylenically unsaturated compounds, to prepare a curable composition.

[0129] The present invention also relates to the use of a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups, preferably the trimercaptocyclododecane, as a crosslinker agent and / or chain transfer agent for thiol-ene systems or compositions comprising ethylenically unsaturated compounds.

[0130] The present invention additionally relates to a crosslinker agent comprising, or consisting essentially of, the polythiol described herein, which may be used in combination with a polymerizable component comprising one or more ethylenically unsaturated compounds.

[0131] The present invention additionally relates to a chain transfer agent for thiol-ene systems comprising, or consisting essentially of, the polythiol described herein, which may be used in combination with an ene component comprising one or more ethylenically unsaturated compounds.ASPECTS OF THE INVENTION

[0132] The invention may be according to the following aspects.

[0133] Aspect 1. A curable composition comprising:a) a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups; and b) a component comprising one or more ethylenically unsaturated compounds.

[0134] Aspect 2. The composition of aspect 1, wherein the at least three -SH groups in the polythiol a) are secondary thiol groups.

[0135] Aspect 3. The composition of aspect 1 or 2, wherein the at least three -SH groups are directly bonded to carbon atoms forming said cycloaliphatic ring.

[0136] Aspect 4. The composition of any one of the preceding aspects, wherein the polythiol a) is the cyclododecanetrithiol.

[0137] Aspect 5. The composition of any one of the preceding aspects, wherein the component b) comprises at least one compound comprising an acrylate functional group ( — O-C(O)-CH=CH2), a methacrylate functional group ( — O-C(O)-C(CH3)=CH2), an acrylamide functional group ( — NH-C(O)-CH=CH2), a methacrylamide functional group ( — NH-C(O)-C(CH3)=CH2), a vinyl sulfone functional group (-SO2-CH=CH2), a maleimide functional group, a vinyl group ( — CH=CH2), a vinyl ether group ( — O-CH=CH2), an allyl group ( — CH2-CH=CH2), an allyl ether group ( — O-CH2-CH=CH2) or a mixture thereof.

[0138] Aspect 6. The composition of any one of the preceding aspects, wherein the component b) is at least one of a (meth)acry late-functionalized monomer, a (meth)acrylate-functionalized oligomer, or mixtures thereof.

[0139] Aspect 7. The composition of any one of the preceding aspects, wherein the component b) is an electron-deficient component and comprises at least one compound comprising one or several polymerizable group(s), preferably an acrylate functional group ( — O-C(O)-CH=CH2), a methacrylate functional group ( — O-C(O)-C(CH3)=CH2), an acrylamide functional group ( — NH- C(O)-CH=CH2), a methacrylamide functional group ( — NH-C(O)-C(CH3)=CH2), a vinyl sulfone functional group (-SO2-CH=CH2), a maleimide functional group or mixture thereof.

[0140] Aspect 8. The composition of any one of the preceding aspects, wherein the component b) comprises at least one compound comprising an acrylate functional group and / or a methacrylate functional group.

[0141] Aspect 9. The composition of any one of the preceding aspects, wherein the component b) is at least one of a (meth)acry late-functionalized monomer, a (meth)acrylate-functionalized oligomer, or mixtures thereof.

[0142] Aspect 10. The composition of any one of the preceding aspects, wherein the composition comprises between 0.1 and 50 wt.% of poly thiol a), relative to the total weight of the composition.

[0143] Aspect 11. The composition of any one of the preceding aspects, wherein the composition comprises between 0.2 and 40 wt.% of poly thiol a), relative to the total weight of the composition.

[0144] Aspect 12. The composition of any one of the preceding aspects, wherein the composition comprises between 0.3 and 30 wt.% of poly thiol a), relative to the total weight of the composition.

[0145] Aspect 13. The composition of any one of the preceding aspects, wherein the composition comprises between 0.4 and 20 wt.% of poly thiol a), relative to the total weight of the composition.

[0146] Aspect 14. The composition of any one of the aspects 1-10, wherein the composition comprises between 0.1 and 10 wt.% of poly thiol a), relative to the total weight of the composition.

[0147] Aspect 15. The composition of any one of the aspects 1-5, wherein the component b) is an electron-rich component, and preferably comprises at least one compound comprising a vinyl group ( — CH=CH2), a vinyl ether group ( — O-CH=CH2), an allyl group ( — CH2-CH=CH2), an allyl ether group ( — O-CH2-CH=CH2), or any mixtures thereof.

[0148] Aspect 16. The composition of aspect 15, wherein the composition comprises from 0.5 to 10 molar equivalent of -SH groups per double bond.

[0149] Aspect 17. The composition of aspect 15 or 16, wherein the composition comprises from 1 to 8 molar equivalent of -SH groups per double bond.

[0150] Aspect 18. The composition of any one of aspects 15-17, wherein the composition comprises from 2 to 6 molar equivalent of -SH groups per double bond.

[0151] Aspect 19. The composition of any one of the preceding aspect s, further comprising at least one of: c) an inhibitor; d) an initiator selected from a free radical initiator, a cationic initiator, and combinations thereof; e) a solvent; and / or f) an additive selected from the group consisting of antioxidants, ultraviolet absorbers, stabilizers, foam inhibitors, flow or leveling agents, colorants, dyes, pigments, dispersants (wetting agents), slip additives, fdlers, elastomers, tougheners, thixotropic agents, matting agents, waxes, and combinations thereof.

[0152] Aspect 20. Use of the curable composition of any one of aspects 1-19, for an adhesive, an ink, a 3D printing material, a sealant, a coating, a photosensible material or a composite. Aspect 21. Method of using the curable composition of any one of aspects 1-19 for an adhesive, an ink, a 3D printing material, a sealant, a coating, a photosensible material or a composite. Aspect 22. Method of making a cured composition, comprising curing the curable composition of any one of aspects 1-19.

[0153] Aspect 23. The method of aspect 22, comprising exposing the curable composition to UV / EB radiation and / or heat.

[0154] Aspect 24. A cured composition obtained by curing the curable composition of any one of aspects 1-19.

[0155] Aspect 25. Use of a polythiol comprising at least three -SH groups, wherein the poly thiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups, preferably the cyclododecanetrithiol, as a crosslinker agent and / or chain transfer agent for thiol-ene systems.

[0156] Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, one of skill in the art will appreciate that certain changes and modifications may be practiced within the scope of the appended claims. In addition, each reference provided herein is incorporated by reference in its entirety to the same extent as if each reference was individually incorporated by reference. Where a conflict exists between the instant application and a reference provided herein, the instant application shall dominate.EXAMPLES

[0157] The following examples illustrate the invention without limiting it.

[0158] Raw materialsTable 1*l,2,4-tris(2-mercaptoethyl)cyclohexane was obtained from 1,2,4-Trivinylcyclohexane provided by Sigma Aldrich (Merck), according to the preparation process used for the preparation of CDT-3SH from cyclododecatriene described below.

[0159] Preparation process of CDT-3SH

[0160] The polythiol was prepared according to the following steps:

[0161] Stage a):

[0162] 774.0 g (10.17 mol) of TAA are introduced into a 3-litre jacketed reactor. The medium is placed under stirring at 5°C and then 142.0 g (3.08 mol) of ethanol are rapidly added. Air is bubbled into the reaction medium via a frit at a flow rate of approximately 0.4 Nl / h and nitrogen is passed into the headspace of the reactor at a flow rate of approximately 4 Nl / h.

[0163] 500 g (3.08 mol) of 1,5,9-cyclododecatriene are subsequently added dropwise via a peristaltic pump over approximately 4h30. Once the addition is finished, 851.7g (18.49 mol) of ethanol are added to the reaction medium.

[0164] The reaction medium is kept stirred at 5 °C approximately overnight.

[0165] A GC / FID analysis shows complete conversion of the 1,5,9-cyclododecatriene.

[0166] The air supply is cut off.

[0167] Stage b) of acidic deprotection:

[0168] The reaction medium temperature is raised to 20°C and 1478.6 g (30.81 mol) of EtOH 96% are added to the reaction medium. The medium is heated to 40°C, and 910.9 g (9.24 mol) of 37% HC1 are added dropwise via a peristaltic pump and then the medium is heated at reflux under nitrogen for 22 h.

[0169] Recovery stage:

[0170] The reaction medium is subsequently cooled to 30°C, the organic phase comprising the thiols is withdrawn and 261.7 g (3.08 mol) of dichloromethane are subsequently added to it.

[0171] The obtained organic phase is then washed four times with 110.9 g (6.16 mol) of water and then concentrated on a rotary evaporator.

[0172] A GC / FID analysis shows complete conversion of the trithioacetate. A polythiol composition comprising 94.84% of trimercaptocyclododecane.Table 2

[0173] Example 1 - Stability and curing time of curable compositions

[0174] The stability of three curable compositions (uncured) was assessed by visual aspect change and viscosity measurement at 25°C. The curing time of the compositions was then assessed after application using a cubic fdm puller to form a 200 pm fdm after curing. The fdm was cured under a 36W LED (365+405 nm) lamp for a certain period (lapse) of time and the surface quality and tackiness were evaluated by rubbing / touching the fdm using a gloved fingerprint. The surface is considered as “cured” when the surface is tack-free. The curing time is the time required to consider the film as “cured”. Detailed compositions and results are presented in Table 2 below.

[0175] Table 3

[0176] The composition containing CDT-3SH exhibits a stability of 9 days at 25°C and requires a curing time of 60 seconds. The poly thiol CDT-3SH therefore represents a favorable compromise compared to the established benchmarks polythiols Thiocure® 340 and KarenzMT™ PEI.

[0177] Example 2 - Viscosity, mechanical properties, aging of cured compositions

[0178] The formulations of the two compositions tested in this example are detailed in Table 4.Table 4

[0179] First, the viscosity at 25 °C and storage stability of the two curable compositions (uncured) were assessed in accordance with the following test methods:Viscosity measurements:• The viscosity of the compositions was measured at 0.5 rpm and 5 rpm using a Brookfield viscometer;• The viscosity change between 0.5 and 5 rpm allow the calculation of the thixotropic index;Storage stability:• The curable compositions were placed in a light-shielded container and allowed to stand at 80°C for 24 hours;• The storage stability was evaluated by measuring the change in viscosity relative to the initial viscosity.

[0180] The wt.% of the polythiol in inventive composition 2.2 was adjusted to match the viscosity of comparative composition 2.1 at 5 rpm.

[0181] Each composition was shaped into a sheet approximately 1 mm thick, then irradiated with UV light using a UV irradiation device of an electrodeless metal halide lamp type (FOTOCURE TFL- 150, manufactured by Tokyo Foton Ltd. ; base-lamp distance d=53 mm; integral of light of UV-A wave: about 7000 mJ / cm) to provide a cured composition.

[0182] The mechanical properties and aging of the two cured compositions were assessed according to the following test methods:Hardness A• Sheets of a UV-cured resin product having a thickness of about 1 mm were laminated on each other to produce a specimen having a thickness of about 10 mm. The Shore hardness A of the specimen was measured using a type-A durometer (manufactured by Kobunshi Keiki Co., Ltd.) at 23 °C.Compression Set• Sheets of a UV-cured resin product cut into a 25-mm square piece were laminated on each other to produce a specimen having a thickness of about 5 mm. The specimen was compressed at a compression ratio of 50% and then determined on the compression recovery performance under the condition of a test temperature of 23°C or 70°C during 22 hours in accordance with JIS K 6253.Tensile properties (Tensile Strength at Break, Percentage of Elongation)• A l mm-thick sheet of a UV-cured resin product was punched into a dumbbell No. 3 shape in accordance with JISK 6251 to produce a test specimen.• A tensile test was carried out under the conditions of a test temperature of 23° C and a tension speed of 100 m / min, and a tensile strength at break and a percentage of elongation were measured.• Tensile strength at break [MPa]=breaking strength / cross-sectional area of fdm• Percentage of elongation [%]=(quantity of breaking elongation / reference length [20 mm]) xlOOAging was assessed by measuring the tensile properties at time to and after aging of 200 hours, 400 hours, 600 hours according to two following conditions• At 85°C and 95% relative humidity, and• At 100°CTable 5* TS: Tensile Strength (in MPa) / RR: Retention Rate (in %, RR= [TS(t)-TS(initial) / TS(initial)]xl00)

[0183] With a lower dosage of polythiol (wt. % and mol. %), the cured composition 2.2 (inventive) nevertheless exhibits enhanced mechanical performances / durability, compared to the cured composition 2.1 (comparative), more precisely: a similar hardness A;a better compression set (capacity of a material or structure to withstand loads tending to reduce size) even at higher temperature; a better flexibility; and a better resistance to hydrolysis and temperature aging.

[0184] This demonstrates that the compositions of the present invention are well-suited to be used as materials for e.g., applications subjected to mechanical stress or harsh environmental conditions.

[0185] The measurement of the tensile strength (TS) and retention rate (RR) after 500 h or 1000 h of aging at 100°C demonstrates the improved durability of the cured compositions of the present invention.

[0186] Example 3 - Curing properties and mechanical performances of cured compositions

[0187] The curing properties and mechanical performances of cured compositions comprising various polythiol contents were assessed as detailed below.

[0188] Samples were exposed simultaneously to the IR analytical beam and to the UV irradiation of LED at 405nm (intensity: 110mW / cm2).

[0189] The following test methods were used:RT-FTIR: the photopolymerization process was monitored using a JASCO 4600 real-time Fourier transform infrared spectroscope (RT-FTIR) operating in transmission mode with a spectral resolution of 8cm1;Surface tackiness: as in example 1;Hardness A: the shore A hardness of 3 mm thick samples was determined using a Shore hardness tester (SAUTER Test HBA Stand);DSC: DSC study for cured thick samples was carried out at a heating and cooling rate of 10°C / min in N2atmosphere using Metier Toledo’s DSC thermal instrument (DSC 1 Star System). All samples underwent a thermal heating ramp starting at -50°C up to 200°C before cooling back down to -50°C, then followed by a second heat cycle -50 to 200°C; andDMA: Dynamic mechanical thermal properties of the samples were measured using a DMA / SDTA861 by Mettler Toledo. The experiments were carried out at a frequency of 1 Hz. The measurements were taken over the temperature range of -50 to 200°C, at a heating rate of 2°C / min and a strain amplitude of 5 pm. The storage modulus and loss modulus, as well as tan(delta), were measured for all the samples under identical conditions.Table 6* Resin: 60 wt.% of CN9002 + 40 wt.% of SR339 + 1 phr TPO-L

[0190] With a lower dosage, the cured compositions of the invention (3.5 to 3.7) exhibit comparable curing behavior and mechanical performances, compared to the cured composition 3.1 to 3.4 (comparative).

[0191] The use of the CDT-3SH polythiol in combination with the mono(meth)acrylate- functionalized monomer and the aliphatic urethane acrylate demonstrates comparable properties than the polythiols typically used in the field, however with a lower dosage, which makes the compositions of the invention significantly more cost effective. Lowering the dosage of polythiols in the composition also helps reduce odors.

Claims

CLAIMS1. A curable composition comprising: a) a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups; and b) a component comprising one or more ethylenically unsaturated compounds.

2. The composition of claim 1, wherein the at least three -SH groups in the polythiol a) are secondary thiol groups.

3. The composition of claim 1 or 2, wherein the at least three -SH groups in the polythiol a) are directly bonded to carbon atoms forming said cycloaliphatic ring.

4. The composition of any one of the preceding claims, wherein the polythiol a) is the cyclododecanetrithiol.

5. The composition of any one of the preceding claims, wherein the component b) is an electron-deficient component and comprises at least one compound comprising one or several polymerizable group(s), preferably an acrylate functional group ( — O-C(O)-CH=CH2), a methacrylate functional group ( — O-C(O)-C(CH3)=CH2), an acrylamide functional group ( — NH-C(O)-CH=CH2), a methacrylamide functional group ( — NH-C(O)-C(CH3)=CH2), a vinyl sulfone functional group (-SO2-CH=CH2), a maleimide functional group or mixture thereof, and more preferably an acrylate functional group and / or a methacrylate functional group.

6. The composition of any one of the preceding claims, wherein the component b) is at least one of a (meth)acrylate-functionalized monomer, a (meth)acrylate-functionalized oligomer, or mixtures thereof.

7. The composition of any one of the preceding claims, wherein the composition comprises between 0.1 and 50 wt.% of polythiol a), relative to the total weight of the composition.

8. The composition of any one of the claims 1-4, wherein the component b) is an electron-rich component, and preferably comprises at least one compound comprising a vinyl group ( — CH=CH2), a vinyl ether group ( — O-CH=CH2), an allyl group ( — CH2-CH=CH2), an allyl ether group ( — O-CH2-CH=CH2), or any mixtures thereof.

9. The composition of claim 8, wherein the composition comprises from 0.5 to 10 molar equivalent of -SH groups per double bond.

10. The composition of any one of the preceding claims, further comprising at least one of: c) an inhibitor; d) an initiator selected from a free radical initiator, a cationic initiator, and combinations thereof; e) a solvent; and / or f) an additive selected from the group consisting of antioxidants, ultraviolet absorbers, stabilizers, foam inhibitors, flow or leveling agents, colorants, dyes, pigments, dispersants (wetting agents), slip additives, fdlers, elastomers, tougheners, thixotropic agents, matting agents, waxes, and combinations thereof.

11. Use of the curable composition of any one of claims 1-10, for an adhesive, an ink, a 3D printing material, a sealant, a coating, a photosensible material or a composite.

12. Method of making a cured composition, comprising curing the curable composition of any one of claims 1-10.

13. The method of claim 12, comprising exposing the curable composition to UV / EB radiation and / or heat.

14. A cured composition obtained by curing the curable composition of any one of claims 1-10.

15. Use of a polythiol comprising at least three -SH groups, wherein the polythiol is in the form of a cycloaliphatic ring comprising between 7 to 15 carbon atoms, optionally substituted by one or several C1-C4 alkyl groups, preferably the cyclododecanetrithiol, as a crosslinker agent and / or chain transfer agent for thiol-ene systems.

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