WO2024099751A1

WO2024099751A1 - Aqueous radiation curable composition

Info

Publication number: WO2024099751A1
Application number: PCT/EP2023/079466
Authority: WO
Inventors: Elodie Siband; Michel Tielemans
Original assignee: Allnex Belgium, S.A.
Priority date: 2022-11-10
Filing date: 2023-10-23
Publication date: 2024-05-16

Abstract

An aqueous radiation curable composition obtained by: a) mixing at least one ethylenically unsaturated compound (A) with at least one reactive ionic external emulsifier (B), wherein the reactive ionic external emulsifier (B) is represented by the general formula (I): D-O-(R1O)n-X (I) wherein: D is a moiety comprising an ethylenically unsaturated group (E); R1 is a linear or branched C2-C6 alkylene group; X is an ionic moiety; and n is in a range from 4 to 50, thereby obtaining a premix; and b) adding water to the premix until a phase inversion occurs.

Description

AQUEOUS RADIATION CURABLE COMPOSITION Technical Field [0001] The present invention relates to an aqueous radiation curable composition and to a coating composition comprising said aqueous radiation curable composition. Background [0002] Plastics coatings represent a significant and high growth segment of the coating industry and target the challenging demand for advanced surface finish technologies covering aesthetics as well as additional protective and functional features. Coatings for the so-called 3C applications - which include computer, communication and consumer electronics – are particularly challenging to formulate as those make use of various low surface energy substrates comprising e.g. polycarbonate and additional synthetic polymers or fibres, and which are known to be difficult to bond substrates. [0003] With the enforcement of evermore stringent VOC emission regulations across the globe, the demand for low VOC coating solutions is growing fast. In that context, waterborne radiation curable coating compositions have become increasingly popular in replacement of solvent borne resins. However, the aqueous radiation curable coating compositions known in the art are known to have limited use for challenging plastic applications due in particular to unsatisfactory adhesion performance. [0004] A partial solution is described e.g. in US 2020/0181451A1 (Su et al.). Without contesting the technical advantages associated with the solutions known in the art, there is still a need for a low VOC radiation curable composition which overcomes at least partially the above-mentioned deficiencies. Summary [0005] According to one aspect, the present disclosure relates to an aqueous radiation curable composition obtained by: a) mixing at least one ethylenically unsaturated compound (A) with at least one reactive ionic external emulsifier (B), wherein the reactive ionic external emulsifier (B) is represented by the general formula (I): D-O-(R1O)n-X (I) wherein: D is a moiety comprising an ethylenically unsaturated group (E); R1 is a linear or branched C2-C6 alkylene group; X is an ionic moiety; and n is in a range from 4 to 50, thereby obtaining a premix; and b) adding water to the premix until a phase inversion occurs. [0006] According to another aspect, the present disclosure is directed to a coating composition comprising an aqueous radiation curable composition as described above. [0007] In still another aspect of the present disclosure, it is provided a process for the manufacturing of an aqueous radiation curable composition, comprising the steps of: a) mixing at least one ethylenically unsaturated compound (A), as described above, with at least one reactive ionic external emulsifier (B), as described above, thereby obtaining a premix; and b) adding water to the premix until a phase inversion occurs. [0008] According to yet another aspect, the present disclosure relates to the use of an aqueous radiation curable composition or a coating composition as described above in computer, communication and consumer electronics, dual cure applications, coating applications, composite applications, three dimensional (3D) applications, printing applications, adhesive applications, paper impregnation applications or thick pigmented systems. Detailed description [0009] According to a first aspect, the present disclosure relates to an aqueous radiation curable composition obtained by: a) mixing at least one ethylenically unsaturated compound (A) with at least one reactive ionic external emulsifier (B), wherein the reactive ionic external emulsifier (B) is represented by the general formula (I): D-O-(R1O)n-X (I) wherein: D is a moiety comprising an ethylenically unsaturated group (E); R1 is a linear or branched C2-C6 alkylene group; X is an ionic moiety; and n is in a range from 4 to 50, thereby obtaining a premix; and b) adding water to the premix until a phase inversion occurs. [0010] In the context of the present disclosure, it has been surprisingly found that an aqueous radiation curable composition as described above is provided with excellent colloidal stability, even under stringent ageing conditions, as well as advantageous formulation flexibility. [0011] It has no less surprisingly been found that an aqueous radiation curable composition as described above is particularly suitable for forming coatings provided with excellent characteristics and performance attributes as regard to adhesion to challenging-to-bond plastic substrates (in particular polycarbonate, acrylonitrile butadiene styrene and combinations thereof), hot water resistance, hydrolysis resistance, visual aesthetics even in complex formulations (such as e.g. metallic or matte formulations), abrasion resistance and low VOC features. [0012] Without wishing to be bound by theory, it is believed that these excellent characteristics and attributes are due in particular to the use of a specific combination of: (a) at least one ethylenically unsaturated compound (A), and (b) at least one reactive ionic external emulsifier (B) as defined above; wherein the aqueous radiation curable composition is specifically obtained by premixing compound (A) with compound (B) and adding water to the obtained premix until a phase inversion occurs. [0013] More specifically, it is believed that this specific combination of components together with the premixing aspect as detailed above contributes to providing the aqueous radiation curable composition with advantageous characteristics, in particular relatively high solid content, relatively small particle size and excellent viscosity features, which in turn result into coatings provided with the excellent characteristics and performance attributes as detailed above. It is further believed that the reactive ionic external emulsifier (B), due in particular to the presence of the ethylenically unsaturated group (E) and the ionic moiety (X) in its structure and to the fact that it is provided with a particular advantageous balance of hydrophilic properties (through its polyalkylene oxide segments (R1O)) and hydrophobic properties (through its moiety (D)), critically contributes to providing the aqueous radiation curable composition with advantageous characteristics as detailed above. The presence of the ethylenically unsaturated group (E) in the structure of the reactive ionic external emulsifier (B) is also believed to prevent (or at least substantially reduce) the presence of free emulsifier after polymerization. The presence of these free or mobile emulsifiers after curing is known to detrimentally affect various properties of the resulting coating, in particular its visual aspect, due to unwanted migration of these free emulsifiers through the coating layer up to its external surface. [0014] As such, the aqueous radiation curable composition of the present disclosure is outstandingly suitable for forming coatings for use in 3C applications. [0015] In the context of the present disclosure, the expression “reactive ionic external emulsifier” is meant to designate an emulsifier which has the ability to copolymerize with monomers through radical polymerizable groups present in the molecule, which further comprises an ionic moiety and which is externally added to stabilize an emulsion. [0016] The aqueous radiation curable composition of the present disclosure comprises, as a first component, at least one ethylenically unsaturated compound (A). [0017] Ethylenically unsaturated compounds (A) for use herein are not particularly limited. Suitable ethylenically unsaturated compounds (A) for use herein will be easily identified by those skilled in the art in the light of the present disclosure. [0018] Compounds (A) for use herein comprise at least one, and typically at least two polymerizable ethylenically unsaturated groups per molecule, also referred to herein as “ethylenically unsaturated functional groups” or “ethylenically unsaturated groups”. By “polymerizable ethylenically unsaturated groups” throughout the present disclosure is meant to designate carbon-carbon double bonds which can undergo radical polymerization under the influence of irradiation. Examples of such groups are (meth)acryloyl, (meth)acrylamide, vinyl, vinylether, allyl, styrenyl, methylstyrenyl, maleyl or fumaryl functional groups. The polymerizable ethylenically unsaturated groups for use herein are generally chosen from (meth)acryloyl groups and/or allyl groups, preferably they are (meth)acryloyl groups, more preferably acryloyl groups. In the present disclosure, the term “(meth)acryloyl” is to be understood as to encompass both acryloyl and methacryloyl groups or derivatives as well as mixtures thereof. [0019] Compounds (A) for use in the present disclosure may be monomeric, oligomeric and/or polymeric ethylenically unsaturated compounds. Blends of monomeric, oligomeric and/or polymeric ethylenically unsaturated compounds (A) may also be used. [0020] Typically, ethylenically unsaturated compounds (A) are monomeric or oligomeric in nature. Advantageously, the compounds (A) for use herein are oligomeric. Typical monomeric compounds (A) have a weight average molecular weight (M_w) in a range from 50 to 300 g/mol, from 100 to 250 g/mol, or even from 100 to 200 g/mol, when measured by conventional gel permeation chromatography (GPC) techniques. Typical oligomeric compounds (A) have a weight average molecular weight (Mw) in a range from 300 to 20,000 g/mol, from 500 to 15,000 g/mol, from 500 to 10,000 g/mol, or even from 800 to 5,000 g/mol, when measured by conventional gel permeation chromatography (GPC) techniques. [0021] In one advantageous aspect, ethylenically unsaturated compounds (A) for use herein are water-insoluble compounds. By “a water-insoluble compound” is meant to designate in the present disclosure an ethylenically unsaturated compound that is not self-emulsifiable or self- dispersible, but forms emulsions or dispersions in water or in aqueous solutions in the presence of one or more reactive ionic external emulsifiers (B) as defined above. More in particular, and according to this advantageous aspect of the disclosure, compounds (A) are non-self- dispersible, non-self-emulsifiable, non-water-dilutable compounds. Typically, compounds (A) of the invention are not self-dispersible compounds. By a “self-dispersible compound” is meant to designate in the present disclosure a compound that, when mixed with water, forms a stable two-phase system of small particles dispersed in water without the aid of an additional emulsifier. By a “self-emulsifiable compound” is meant to designate in the present disclosure a compound that, when mixed with water, forms a stable two-phase system of small droplets dispersed in water without the aid of an additional emulsifier. By “stable” is meant to designate herein that there is substantially no coalescence (droplets) nor flocculation (particles) leading to phase separation, creaming or sedimentation of the heterogeneous system after 2 or more days, typically 4 or more days, preferably not even after 10 days at 60° C. Typically, compounds (A) for use herein are not water-dilutable compounds. By a “water-dilutable compound” is meant to designate in the present disclosure a compound that permits to form a homogeneous, single phase mixture when the compound is mixed with water over a concentration range of 5 to 75 wt % of water in the total mass of water and the compound, and this in the absence of emulsifiers. [0022] Compounds (A) are typically characterized by an amount of copolymerizable ethylenically unsaturated groups of at least 1 meq/g, at least 2 meq/g, at least 3 meq/g, at least 4 meq/g, at least 5 meq/g, at least 6 meq/g, at least 7 meq/g, at least 8 meq/g, or even at least 9 meq/g. Typically this amount does not exceed 13 meg/g or even 12 meq/g. The amount of ethylenically unsaturated groups is typically measured by nuclear magnetic resonance spectroscopy (NMR) according to techniques well known in the art, and is expressed in meq per g of solid material. [0023] In an exemplary aspect, ethylenically unsaturated compounds (A) for use herein comprise at least 2, at least 4, at least 6, at least 8, or even at least 10 or more ethylenically unsaturated functional groups per molecule. [0024] Advantageously, the compounds (A) combine a functionality and degree of unsaturation as indicated above. In particular, preferred compounds (A) for use herein are characterized by a functionality of at least 2, at least 4, at least 6, at least 8, or even at least 10 or more ethylenically unsaturated groups per molecule; and by an amount of ethylenically unsaturated groups of at least 4 meq/g, at least 6 meq/g, at least 8 meq/g, or even at least 9 meq/g. [0025] According to an exemplary aspect, ethylenically unsaturated compounds (A) for use in the present disclosure are (meth)acrylated compounds, in particular selected from the group consisting of urethane (meth)acrylates (A1), polyester (meth)acrylates (A2), polyepoxy (meth)acrylates (A3), polycarbonate (meth)acrylates (A4), polyether (meth)acrylates (A5), and polyacrylic (meth)acrylates (A6). Exemplary ethylenically unsaturated compounds (A) for use herein are amply detailed in U.S. Patent Application US2014/0377466-A1 (Tielemans et al.), the content of which is fully incorporated herein by reference. [0026] According to an advantageous aspect of the disclosure, the ethylenically unsaturated compound (A) for use herein is selected from the group consisting of urethane (meth)acrylates (A1), polyester (meth)acrylates (A2), epoxy (meth)acrylates (A3), and any combinations or mixtures thereof. [0027] In a preferred aspect, the ethylenically unsaturated compound (A) is selected from the group consisting of urethane (meth)acrylates (A1). Urethane (meth)acrylates have surprisingly been found to provide excellent compatibility with the reactive ionic external emulsifier (B), excellent stability of the aqueous radiation curable composition (and of the resulting water- based emulsion), which in turn result into enhanced characteristics and performance attributes of the corresponding radiation cured coating or article. Moreover, the use of urethane (meth)acrylates (A1) as ethylenically unsaturated compound (A) has been found to provide outstanding adhesion performance on challenging-to-bond plastic substrates (in particular polycarbonate, and acrylonitrile butadiene styrene, and any combinations thereof) which are particularly used in 3C applications. [0028] In a beneficial aspect of the aqueous radiation curable composition of the present disclosure, the ethylenically unsaturated compound (A) for use herein further comprises ionic functional groups. Advantageously, the ionic functional groups for use herein can be at least partly neutralized by an (organic or inorganic) neutralizing agent (C) to provide a salt therefrom. [0029] Advantageously, the ionic functional groups for use herein are anionic functional groups, in particular anionic salts groups derived from acidic functional groups in particular selected from the group consisting of carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, and any combinations or mixtures thereof. Accordingly, preferred anionic salts groups for use herein are selected from carboxylate, sulfonate and phosphonate salt groups. [0030] More advantageously, the ionic functional groups for use herein are pendant hydrophilic groups, which may render the corresponding ethylenically unsaturated compound (A) at least partially self-dispersible, self-emulsifiable, water-soluble or water-dilutable. [0031] According to an advantageous aspect, the ethylenically unsaturated compound (A) further comprising acidic (anionic) functional groups has an acid value of at least 5 mgKOH/g, at least 10 mgKOH/g, at least 20 mgKOH/g, at least 50 mgKOH/g, or even at least 100 mgKOH/g, when the acid value is determined according to ASTM D974-64 standard test method. [0032] In the context of the present disclosure, it has been found that ethylenically unsaturated compound (A) further comprising ionic functional groups (in particular anionic groups derived from acidic functional groups) not only provide excellent compatibility/affinity with the reactive ionic external emulsifier (B), but also advantageously affect the overall stability of the aqueous radiation curable composition (and of the resulting water-based emulsion) by facilitating the obtaining of relatively small particle size, which in turn result into enhanced characteristics of the corresponding radiation cured coating or article. Without wishing to be bound by theory, it is believed that the presence of the ionic functional groups in compound (A) provides an additional “internal” stabilization of the aqueous radiation curable composition, which together with the “external” stabilization provided by the reactive ionic emulsifier (B), contributes to provide an advantageous dual stabilization effect. [0033] It has been further found that ethylenically unsaturated compounds (A), in particular those derived from acrylic oligomers, may be advantageously used in dual (radiation and thermal) curing applications. [0034] Ethylenically unsaturated compounds (A) further comprising ionic functional groups are well known in the art, and are either commercially available as such, or may be obtained according to conventional techniques also well known to those skilled in the art. Exemplary ethylenically unsaturated compounds (A) further comprising ionic functional groups for use herein, methods for obtaining thereof, including neutralization steps of hydrophilic functional groups with typical neutralizing agents, are amply described e.g. in PCT Application WO 2022/128462 (Tielemans), the content of which is fully incorporated herein by reference. Typical neutralizing agents for use herein comprise organic tertiary amines (such as e.g. triethylamine) and inorganic bases (such as e.g. sodium hydroxide). [0035] In another beneficial aspect of the aqueous radiation curable composition of the present disclosure, the ethylenically unsaturated compound (A) for use herein is at least partially bio- based, and has in particular a biobased content of more than 10%, more than 20%, more than 40%, more than 50%, more than 60%, or even more than 80% by weight of total carbon content of the ethylenically unsaturated compound (A), when the biobased content is determined according to ASTM D6866 standard test method. Exemplary bio-based ethylenically unsaturated compounds (A) for use herein and methods for obtaining thereof, are also amply described in PCT Application WO 2022/128462 (Tielemans), the content of which is fully incorporated herein by reference. [0036] The aqueous radiation curable composition of the present disclosure comprises, as a second component, at least one reactive ionic external emulsifier (B), wherein the reactive ionic external emulsifier (B) is represented by the general formula (I): D-O-(R1O)_n-X (I) wherein: D is a moiety comprising an ethylenically unsaturated group (E); R1 is a linear or branched C₂-C₆ alkylene group; X is an ionic moiety; and n is in a range from 4 to 50. [0037] Reactive ionic external emulsifiers (B) for use herein are not particularly limited, as long as they satisfy the above-described general formula (I). Suitable reactive ionic external emulsifiers (B) for use herein will be easily identified by those skilled in the art in the light of the present disclosure. [0038] In the context of the present disclosure, it has been found that when the number of repeating alkylene oxide groups (R¹O), which is represented by integer n in general formula (I), is specifically kept within the range from 4 to 50, a particular advantageous balance of hydrophilic properties (through its polyalkylene oxide segments (R1O)) and hydrophobic properties (through its moiety (D)) is achieved which critically contributes to providing the aqueous radiation curable composition with advantageous characteristics as detailed hereinbefore. Furthermore, the formation of water pockets is minimized due to the lower content of the emulsifier (B) which can be used, while still maintaining excellent colloidal stability of the aqueous radiation curable composition and excellent performance attributes of the resulting cured coating or article such as e.g. (hot) water resistance, hydrolysis resistance and visual appearance. [0039] More specifically, when integer n is below 4, the reactive ionic external emulsifier (B) is inadequate in terms of hydrophilicity, which detrimentally affects the overall stability of the aqueous radiation curable composition. Moreover, the mechanical stability of the resulting cured coating or article proves to be unsatisfactory. [0040] Further, when integer n is greater than 50, the hydrophilicity of the reactive ionic external emulsifier (B) is too high which leads to increased formation of water pockets and reduced water release, which again detrimentally affects not only the overall stability of the aqueous radiation curable composition but also various performance attributes of the resulting cured coating or article such as e.g. (hot) water resistance, hydrolysis resistance and visual appearance. [0041] In an advantageous aspect of the reactive ionic external emulsifier (B), integer n is no greater than 50, no greater than 45, no greater than 40, no greater than 35, no greater than 30, no greater than 25, no greater than 20, no greater than 15, or even no greater than 10. [0042] More advantageously, n is in a range from 4 to 45, from 4 to 40, from 4 to 35, from 4 to 30, from 5 to 30, from 5 to 25, from 5 to 20, from 6 to 20, from 6 to 15, from 8 to 15, from 8 to 12, or even from 9 to 11. [0043] In another advantageous aspect, R₁ is a linear or branched C₂-C₄ alkylene group, in particular a linear C2-C4 alkylene group, more in particular a linear C2-C3 alkylene group, even more in particular a linear C₂ alkylene group. Preferably, R₁ is selected to be ethylene. [0044] According to still another advantageous aspect of the reactive ionic external emulsifier (B), the ethylenically unsaturated group (E) which is comprised in moiety (D) is selected from the group consisting of allyl group, vinyl group, propenyl group, allyloxy, vinyloxy, propenyloxy, allyloxymethyl vinyloxymethyl, propenyloxymethyl, (meth)acryloyl, and any combinations or mixtures thereof. Preferably, the ethylenically unsaturated group (E) for use herein is selected from the group consisting of allyl group, vinyl group, propenyl group, and any combinations or mixtures thereof. [0045] In yet another advantageous aspect of the reactive ionic external emulsifier (B), the moiety (D) for use herein is selected from the group of linear or branched alkyl groups, linear or branched aryl groups, linear or branched alkyl ether groups, linear or branched aryl ether groups, additionally substituted with the ethylenically unsaturated group (E). [0046] According to a more advantageous aspect, the moiety (D) for use herein is represented by the general formula (II): R3-O-CH₂-CHR2- (II) wherein: R2 is : -CH₂-O-CH₂-CH=CH₂; R3 is a linear or branched (C8-C14) alkyl group, in particular a linear (C10-C12) alkyl group; or by the general formula (III): R3-CH 2 2-CHR - (III) wherein: R2 is : -CH2-O-CH2-CH=CH2; R³ is a linear or branched (C8-C14) alkyl group, in particular a linear (C10-C12) alkyl group; or by the general formula (IV): (E)_m1

wherein: (E) is: -CH=CR4-CH₃; or -CH -CR4 2 =CH2 wherein R4 is H or a linear or branched (C1-C6) alkyl group; (R5) is: and

[0047] In yet another advantageous aspect of the reactive ionic external emulsifier (B), the ionic moiety (X) for use herein is an anionic moiety preferably selected from the group consisting of sulfate groups, sulphonate groups, phosphate groups, phosphonate groups, phosphite groups, and any combinations or mixtures thereof. Preferably, the ionic moiety (X) for use herein is selected from sulfate groups. [0048] As it will be easily apparent to those skilled in the art, the ionic moiety (X) will typically be associated with a suitable counterion. Exemplary counterions for use herein are typically selected from the group of sodium cation, ammonium cation, quaternary ammonium cations, and any mixtures thereof. Preferably, the counterion for use herein is selected to be ammonium cation as the later provides the corresponding coating with outstanding (hot) water resistance. [0049] In the context of the present disclosure, the use of an ionic emulsifier as detailed above has been found to be absolutely critical to provide stable aqueous radiation curable compositions according to the present disclosure. In contrast, the use of nonionic emulsifiers, including reactive nonionic emulsifiers, does not permit obtaining stable aqueous radiation curable compositions. [0050] According to another more advantageous aspect, the reactive ionic external emulsifier (B) for use herein is selected from the group consisting of (ethylenically unsaturated derivatives of) polyoxyethylene alkyl ether sulfate (ammonium) salts, and polyoxyethylene aryl ether sulfate (ammonium) salts, in particular polyoxyethylene styrenated phenyl ether sulfate (ammonium) salts. [0051] According to an even more advantageous aspect, the reactive ionic external emulsifier (B) for use herein is selected from the group consisting of polyoxyethylene (allyloxymethyl) alkyl ether sulfate (ammonium) salts, polyoxyethylene (allyloxymethyl) alkoxy ether sulfate (ammonium) salts, polyoxyethylene (propenyl) aryl ether sulfate (ammonium) salts, in particular polyoxyethylene styrenated phenyl (propenyl) ether sulfate (ammonium) salts. [0052] According to a particularly preferred aspect, the reactive ionic external emulsifier (B) for use in the aqueous radiation curable compositions according to the present disclosure is selected from the group consisting of: ; and wherein:

m3 is 1 or 2; and R³ and n are as defined hereinbefore. [0053] A further exemplary reactive ionic external emulsifier (B) for use herein is represented by the following formula: wherein R3 and n are as defined hereinbefore. [0054] Suitable reactive ionic external emulsifiers (B) for use herein are commercially available under the trade designation Hitenol® or Reasop®. [0055] In one advantageous aspect, the aqueous radiation curable composition of the present disclosure is (substantially) free of (reactive and/or non-reactive) non-ionic (external) emulsifiers, in particular (substantially) free of reactive non-ionic (external) emulsifiers. [0056] In another advantageous aspect, the aqueous radiation curable composition of the present disclosure comprises exclusively (reactive and non-reactive) ionic (external) emulsifiers. [0057] In still another advantageous aspect of the present disclosure, the aqueous radiation curable composition comprises exclusively reactive ionic external emulsifiers (B) represented by the general formula (I). In other words, and according to this particular aspect, the (reactive) emulsifiers comprised in the aqueous radiation curable composition are exclusively reactive ionic external emulsifiers (B) represented by the general formula (I). [0058] The aqueous radiation curable composition of the present disclosure may further comprise as an additional, but optional component, a further compound (F). [0059] Compounds (F) for use herein are not particularly limited. Suitable compounds (F) for use herein will be easily identified by those skilled in the art in the light of the present disclosure. Compounds (F) will be typically selected depending on the additional properties that are sought after and/or targeted applications for the aqueous radiation curable composition. Compounds (F) can be oligomeric or polymeric in nature, and can bear various functional groups such as e.g. acrylic, silicone and halogen functional groups. [0060] Compounds (F) may be added at various steps of the water-based emulsion formation. In a typical aspect, they are mixed with the at least one ethylenically unsaturated compound (A) and the at least one reactive ionic external emulsifier (B), thereby obtaining a premix. In an alternative aspect, the compounds (F) may be subsequently added to the premix formed by mixing the at least one ethylenically unsaturated compound (A) and the at least one reactive ionic external emulsifier (B). Alternatively still, the compounds (F) may be added after the water-based emulsion has been formed following suitable phase inversion. [0061] In an advantageous aspect, the compound (F) for use herein is selected from the group of co-emulsifiers and additional surfactants. More advantageously, the compound (F) for use herein has the ability to modify, in particular increase, the overall pH of the aqueous radiation curable composition. Particularly advantageous compound (F) for use herein includes acrylic- based and alkyd/acrylic-based resins, in particular acrylic resins. [0062] As indicated hereinbefore, the aqueous radiation curable composition is obtained by adding water to a premix obtained by mixing the at least one ethylenically unsaturated compound (A) with the at least one reactive ionic external emulsifier (B). More specifically, the water is added until a phase inversion occurs. [0063] The expression “phase inversion” is well known in the art of emulsion chemistry, and it is well within the capabilities of those skilled in the art to achieve phase inversion in aqueous systems, thereby obtaining water-based emulsions. Phase inversion emulsification is amply described e.g. in scientific publication “Phase inversion emulsification: Current understanding and applications”, A. Perazzo, V. Preziosi, S. Guido; Advances in Colloid and Interface Science, 222 (2015), 581–599; and in reference book : “Nanoemulsions: Formulation, Applications, and Characterization” (2018), edited by Seid Mahdi Jafari, D. Julian McClements, Chapter 3 (Catastrophic Phase Inversion Techniques for Nanoemulsification) by Perazzo, Antonio and Valentina Preziosi. [0064] In a typical aspect of the aqueous radiation curable composition according to the present disclosure, water is added to the premix until a phase inversion occurs resulting into forming a water-based emulsion. Advantageously, water is added to the premix until a catastrophic phase inversion occurs. [0065] In an advantageous aspect of the present disclosure, the phase inversion resulting from the addition of water into a premix obtained by mixing the at least one ethylenically unsaturated compound (A) with the at least one reactive ionic external emulsifier (B) occurs without using forced emulsification techniques, i.e. without applying substantial pressure to the mixture. In particular, the phase inversion occurs without using high shear force or high pressure treatment, which are typically assisted with high pressure and/or high shear homogenizers or emulsifying equipment. In other words, the water-based emulsion resulting from the phase inversion described in the present disclosure does not correspond to a forced emulsification type. [0066] In the context of the present disclosure, the sequence of addition of water, compound (A) and emulsifier (B) has been found to be absolutely critical to provide stable aqueous radiation curable compositions according to the present disclosure. Indeed, it has surprisingly been found that - in order to obtain suitable phase inversion and a resulting stable aqueous radiation curable composition - the initial formation of a premix comprising the compound (A) and the emulsifier (B) is required before actually adding water. In contrast, when water is first mixed with the emulsifier (B) followed by the addition of the compound (A), a suitable phase inversion cannot be achieved and therefore a stable aqueous radiation curable composition ( emulsion) cannot be obtained. Without wishing to be bound by theory, it is believed that the ambivalent range around the phase inversion, involving the transition from water-in-oil to oil- in-water, is particularly suitable for achieving droplet size reduction towards stable emulsions with high droplet surface area. [0067] According to an advantageous aspect, the at least one reactive anionic external emulsifier (B) is (pre-)diluted in water prior to mixing with the at least one ethylenically unsaturated compound (A), thereby forming the premix comprising the compound (A) and the (diluted) emulsifier (B). Typically, water will then be added to this premix until a phase inversion occurs. The predilution of the emulsifier in water prior to mixing with the at least one ethylenically unsaturated compound (A), has been found to advantageously affect not only the formation of the phase inversion, but also the overall stability of the resulting aqueous radiation curable composition (emulsion). [0068] In one advantageous aspect, the aqueous radiation curable composition of the present disclosure has a particle (droplet) size no greater than 800 nm, no greater than 600 nm, no greater than 400 nm, no greater than 350 nm, no greater than 300 nm, no greater than 250 nm, no greater than 200 nm, no greater than 150 nm, no greater than 100 nm, or even no greater than 80 nm, when determined by DLS measurements according to the test method described in the experimental section. [0069] In another advantageous aspect, the aqueous radiation curable composition has a particle (droplet) size in a range from 50 to 1000 nm, from 60 to 800 nm, from 65 to 600 nm, from 65 to 400 nm, from 65 to 350 nm, from 70 to 300 nm, from 70 to 250 nm, from 70 to 200 nm, from 70 to 150 nm, or even from 70 to 100 nm, when determined by DLS measurements according to the test method described in the experimental section. [0070] In still another advantageous aspect, the aqueous radiation curable composition has a solid content greater than 30 wt.%, greater than 35 wt.%, greater than 40 wt.%, greater than 45 wt.%, greater than 50 wt.%, greater than 55 wt.%, greater than 60 wt.%, or even greater than 65 wt.%, when determined by gravimetric method according to the test method described in the experimental section. [0071] In yet another advantageous aspect, the aqueous radiation curable composition has a solid content in a range from 35 to 65 wt.%, from 40 to 55 wt.%, from 45 to 55 wt.%, or even from 50 to 55 wt.%, when determined by gravimetric method according to the test method described in the experimental section. [0072] According to another beneficial aspect, the aqueous radiation curable composition as described herein has a viscosity greater than 10 mPa.s, greater than 50 mPa.s, greater than 100 mPa.s, greater than 200 mPa.s, greater than 400 mPa.s, greater than 600 mPa.s, greater than 800 mPa.s, greater than 1000 mPa.s, or even greater than 1500 mPa.s, when determined according to the test method described in the experimental section. [0073] According to more beneficial aspect, the aqueous radiation curable composition has a viscosity in a range from 5 to 1500 mPa.s, from 5 to 1000 mPa.s, from 10 to 800 mPa.s, from 50 to 800 mPa.s, from 50 to 600 mPa.s, from 100 to 600 mPa.s, or even from 100 to 400 mPa.s, when determined according to the test method described in the experimental section. [0074] The aqueous radiation curable composition of the present disclosure is provided with advantageous characteristics, in particular relatively high solid content, relatively small particle size and relatively low viscosity, which not only beneficially affects its overall stability, but also contributes to providing the corresponding coatings and articles with the excellent characteristics and performance attributes as detailed hereinbefore. [0075] Advantageously, the aqueous radiation curable composition as described herein may be at least partially bio-based, and has in particular a biocarbon content of more than 10%, more than 20%, more than 40%, more than 50%, more than 60%, or even more than 80% by weight of total carbon content of the composition, when the biobased content is determined according to ASTM D6866 standard test method. [0076] In a typical aspect, the aqueous radiation curable composition of the present disclosure comprises at least 0.5 wt.%, at least 1 wt.%, at least 2 wt.%, at least 3 wt.%, at least 4 wt.%, or even at least 5 wt.%, of reactive ionic external emulsifiers (B), based on the total weight of compounds (A) and (B). [0077] In another typical aspect, the aqueous radiation curable composition of the present disclosure comprises from 0.5 to 30 wt.%, from 0.5 to 25 wt.%, from 1 to 25 wt.%, from 2 to 25 wt.%, from 2 to 20 wt.%, from 3 to 20 wt.%, from 5 to 15 wt.%, or even from 5 to 10 wt.%, of reactive ionic external emulsifiers (B), based on the total weight of compounds (A) and (B). [0078] In another typical aspect, the aqueous radiation curable composition of the present disclosure comprises from 70 to 99.5 wt.%, from 75 to 99.5 wt.%, from 75 to 99 wt.%, from 75 to 98 wt.%, from 80 to 98 wt.%, from 80 to 97 wt.%, from 85 to 95 wt.%, or even from 90 to 95 wt.%, of ethylenically unsaturated compounds (A), based on the total weight of compounds (A) and (B). [0079] As customary in the technical field, the aqueous radiation curable composition of the present disclosure may further comprise various additional ingredients depending on the targeted applications and properties for such composition. In a typical aspect, the aqueous radiation curable composition further comprises at least one additive selected from the group consisting of photo-initiators, inhibitors, anti-oxidants, biocides, UV stabilizers, UV absorbers, nanoparticles, dispersing agents, slip aids, fillers, plasticizing agents, flow additives, anti- foaming additives, rheology modifiers, anti-settling agents, wetting agents, defoaming agents, fire retardant agents, leveling agents, slip agents, water scavengers, matting agents, waxes, pigments, dyes, co-solvents, resinous materials dispersed or solubilized in the composition, and any combinations or mixtures thereof. [0080] In one advantageous aspect, the aqueous radiation curable composition may further comprise one or more external thermal crosslinkers that allow dual cure (radiation and thermal). Examples of suitable crosslinkers are (blocked) polyisocyanates, polyaziridines, polycarbodiimides, polyepoxides, polyalkoxysilanes and metal salts like zirconium ammonium carbonate. Particularly suitable are polyisocyanates, in particular hydrophilic polyisocyanates commercially available from Covestro AG under trade designation BAYHYDUR. [0081] The aqueous radiation curable composition of the present disclosure can be prepared in various ways according to techniques well known to those skilled in the art. In a typical procedure, the composition is prepared by blending compounds (A), (B), optionally (F) and possibly other ingredients at a temperature between 20 and 80°C under high shear using for instance a cowless propeller at 20 to 2000 rpm (depending on the cowless diameter, the vessel diameter and the volume to be stirred). Water is added during a period of time of between 5 and 60 minutes at a temperature of between 15 and 80°C in such an amount to obtain an aqueous composition with a solid content corresponding to the phase inversion, typically near 80%. [0082] Typically, aqueous radiation curable composition of the present disclosure can be referred to as an aqueous emulsion, more typically an oil-in-water emulsion. The aqueous radiation curable composition as disclosed herein typically comprises from 25 to 95 wt.%, more typically from 35 to 60 wt.% of water, based on the total weight of the composition. The compositions according to the present disclosure typically comprises less than 25 wt.%, less than 20 wt.%, less than 15 wt.%, less than 10 wt.%, less than 5 wt.%, or even less than 1 wt.%, of organic solvents and volatile organic compounds (VOC), based on the total weight of the composition. Advantageously, the aqueous radiation curable compositions according to the present disclosure are free of organic solvents and volatile organic compounds. [0083] According to another aspect, the present disclosure is directed to a coating composition comprising an aqueous radiation curable composition as described above. The aqueous radiation curable compositions disclosed herein are indeed particularly well suited for preparing coatings. All particular and preferred aspects relating to, in particular, the ethylenically unsaturated compounds (A) and the reactive ionic external emulsifiers (B), and described hereinbefore in the context of the aqueous radiation curable composition, are fully applicable to the coating composition. [0084] Advantageously, the coatings obtained from the aqueous radiation curable composition as described are provided with excellent characteristics and performance attributes as regard to adhesion to challenging-to-bond plastic substrates (in particular polycarbonate and acrylonitrile butadiene styrene), hot water resistance, hydrolysis resistance, visual appearance and gloss level even in complex formulations (such as e.g. metallic or matte formulations), abrasion resistance and low VOC features. [0085] In an advantageous aspect, the coating composition is a hardcoat composition. As such, the aqueous radiation curable composition of the present disclosure is outstandingly suitable for forming coatings for use in 3C applications, which are of particular interest in the context of the present disclosure. The product applications in this industry segment are indeed endless and they can be typically associated to consumer electronics (like mobile phone, computer, television, compact disk), to automotive plastics for interior application (like dashboard, trim) or exterior application (like headlight, mirror, bumper, wheel cover) and to industrial plastics (like film, label, box, toy, sport equipment, garden furniture). [0086] The aqueous radiation curable compositions according to the present disclosure are also suitable for use in overprint varnishes, inks, adhesives and for coating three-dimensional articles. [0087] According to yet another aspect, the present disclosure therefore relates to an ink (e.g. inkjet), overprint varnish, adhesive or three-dimensional article comprising an aqueous radiation curable composition or a coating composition as described above. [0088] Yet another aspect of the disclosure relates to an article or substrate coated, printed or treated, at least partially, with an aqueous radiation curable composition, a coating composition, an ink, an overprint, a varnish or an adhesive as described above. [0089] In still another aspect of the present disclosure, it is provided a process for the manufacturing of an aqueous radiation curable composition, comprising the steps of: a) mixing at least one ethylenically unsaturated compound (A), as described above, with at least one reactive ionic external emulsifier (B), as described above, thereby obtaining a premix; and b) adding water to the premix until a phase inversion occurs. [0090] In an advantageous aspect of this process, the mixing step a) comprises mixing the at least one ethylenically unsaturated compound (A) with the at least one reactive ionic external emulsifier (B) and with a further compound (F), wherein the compound (F) is in particular selected from the group of co-emulsifiers and additional surfactants. [0091] Advantageously still, the process for the manufacturing of an aqueous radiation curable composition further comprises the step of (pre-)diluting the at least one reactive ionic external emulsifier (B) in water prior to performing the step of mixing with the at least one ethylenically unsaturated compound (A). [0092] According to yet another aspect, the present disclosure relates to a process for coating an object or a substrate, comprising the steps of: a) providing an aqueous radiation curable composition or a coating composition as described above, b) applying the composition onto at least part of the surface of the object or the substrate, and c) curing the composition by subjecting the coated surface to actinic radiation and/or thermal energy. [0093] Typically the curing step is preceded by a step of evaporating water. Typically at least 98% of the water, preferably at least 99%, preferably all of the water is evaporated. The active energy rays used for curing preferably are ultraviolet rays, electron beam, X-rays, radioactive rays or high frequency waves. Ultraviolet rays having a wavelength of from 180 to 400 nm are particularly preferred from economical viewpoint. Curing by irradiation may be followed, or alternatively replaced, by thermal curing in the presence of suitable external (thermal) crosslinkers. [0094] In a particular aspect of the invention the article or substrate comprises plastic, more in particular is made from plastic. In another particular execution, the article or substrate comprises wood. [0095] Aqueous radiation curable compositions or a coating compositions as described above are typically cured by ultraviolet irradiation, generally in the presence of photo-initiator. Alternatively, they can also be cured by electron-beam irradiation, allowing the use of compositions free of photo-initiator. The compositions according to the invention are providing extremely rapid curing characterized by a higher reactivity allowing higher line speed or less irradiative energy curing and increased productivity. Low energy ultraviolet light sources can also be used (LED lamps). [0096] According to yet another aspect, the present disclosure relates to the use of an aqueous radiation curable composition or a coating composition as described above in computer, communication and consumer electronics, dual cure applications, (wood and flexible) coating applications, composite applications, three dimensional (3D) applications, (inkjet) printing applications, adhesive applications, paper impregnation applications or thick pigmented systems.

EXAMPLES [0097] The present disclosure is further illustrated by the following examples. These examples are merely for illustrative purposes only and are not meant to be limiting on the scope of the appended claims. [0098] Throughout the present disclosure and example section, the following test and measurement methods are used to characterize the exemplary aqueous radiation curable compositions and the coatings obtained therefrom. Test Methods: A) Particle size [0099] Dynamic light scattering (DLS) measurements are used to characterize the hydrodynamic size of particles in the various aqueous compositions. Prior to the DLS measurements, the concentrated compositions are diluted using deionized distilled water, thereby obtaining a particle concentration of 0.05 w/w%. The diluted composition are then filtered. Subsequently, DLS measurements are performed at 23 °C using a Delsa Nano-c particle analyzer of Beckman–Coulter. Incident monochromatic light used in the DLS measurement has a wavelength of λ = 658 nm. Scattered light is detected in near-backscattering geometry at an angle of 165°. The z-average particle size along with the polydispersity index is determined from a second-order cumulant analysis of the electric-field auto-correlation function. The single-particle diffusion coefficient is then estimated from the average decay constant. Therefrom, using Stokes’ relationship, a median particle diameter d50 can be derived. B) Solid content [0100] The solid content (SC) of the various aqueous compositions is determined by gravimetric method. For the radiation-curable emulsions, the gravimetric method comprises drying for 2 hours at 120°C. C) Viscosity [0101] The viscosity of the various aqueous compositions is measured at 23°C with a cone and plate type rheometer MCR092 (Paar-Physica) according to test method DIN EN ISO 3219. A fixed shear rate of 25 s-1 is used. D) Colloidal stability [0102] The colloidal stability of the various aqueous compositions is assessed at 23°C by visually observing the decantation and/or phase separation (expressed in percent of the total height) on samples weighing 20g and placed in an oven at 60°C. The colloidal stability is herein reported as the number of days before a sedimentation exceeding 2% of the total height of the sample. In the context of the present disclosure, a good colloidal stability is achieved when no product deterioration is observed during 10 days at 60°C. E) Molecular weight and polydispersity [0103] The number-average molecular weight (Mn), the weight-average molecular weight (Mw) and polydispersity (D) are determined by conventional gel permeation chromatography (GPC) with Polystyrene standards EasyCal from Polymer Laboratories (Molecular Weight range: 200 – 400.000 g/mol). The samples are dissolved (1.0% wt./wt.) in tetrahydrofuran (THF) containing 0.5% toluene as Flow rate marker. The analysis are performed by liquid chromatography (Merck-Hitachi L7100) equipped with 3 PLGel Mixed-D LS polystyrene-divinylbenzene GPC columns (300 X 7.5mm X 5µm). The components of the sample are separated by the GPC columns based on their molecular size in solution and detected by a Refractive Index detector. The data are gathered and processed by Polymer Laboratories Cirrus GPC software. F) Gloss level [0104] The evaluation of the gloss level is carried out on the coating formed on Leneta™ Plain White Chart. The gloss level values are given in gloss units [GU] for an angle of 60° and determined according to Test Method DIN EN ISO 2813. G) Adhesion [0105] Adhesion performance (initial adhesion ADH) of the coatings to the surface of the corresponding substrate is assessed using a cross hatch test according to Test Method ASTM D3359 B. In each case, 5 parallel cuts of 1cm long and spaced by 1mm, are first made in the coating using a knife. Then, 5 parallel cuts of 1cm long and spaced by 1mm, are made in the transversal direction. Subsequently, an adhesive tape (Scotch®) is firmly pressed on the cross- cut coating and removed rapidly. The damage to the cross-cut surface area of the coating, which us due to adhesion loss, is expressed in a 0B-5B scale, wherein a score of 5 corresponds to the best adhesion. H) Hot water resistance [0106] This resistance test is performed only on those coatings presenting an excellent initial adhesion (ADH test = 5B). The coating is immersed in hot water (temperature of 80 or 85°C) for a period of 30 or 60 minutes. The cross hatch tape adhesion performance is re-evaluated on the dried coating according to the procedure described hereinbefore. The hot water resistance test is passed when at least a score of 4B is obtained. I) Hydrolysis resistance [0107] This resistance test is performed only on those coatings presenting an excellent initial adhesion (ADH test = 5B) and according to industry test standard VW TL 226 (Volkswagen AG). The coated substrate is placed in a humidity chamber for a period of 96 hours at 60°C and 95% relative humidity. The coating of the coated substrate is then evaluated on visual damage, gloss level and cross hatch adhesion after humidity testing. The hydrolysis resistance test is considered passed when the coating is not visually damaged and when the same level of gloss and adhesion is achieved before and after the test. J) Scratch resistance [0108] The scratch resistance is determined using Resistant Coating to Abrasion (RCA) abrader – Norman Tool Tester according to test method ASTM F-2357. The RCA test is performed using a Standard paper as the abrading material. Abrasion is made by pressing the standard paper on the coated polycarbonate substrate with the specific load (175 g). The paper is in contact with the rubber ring on the reverse side. The result is expressed as the number of cycles necessary before the coated substrate starts to visually show damage, haze or white areas. The higher the number of cycles, the better is the abrasion resistance. K) Hardness [0109] The measurement method relates to the surface hardness. A coating having a thickness of 120 micrometres when applied wet to a glass substrate is dried for 5 minutes at 40°C, then 5 minutes at 80°C and finally cured 3 times under an UV-lamp (Hg) of 80 W/cm at a speed corresponding to the reactivity. The coated samples are stabilized during 24 hours in a conditioned room (20°C, 50% humidity) and a pendulum hardness (Persoz) is determined in seconds on 3 places of the surface. The mean value is calculated. Raw materials: [0110] In the examples, the following raw materials and starting products are used: Ebecryl®1290 is a hexafunctional aliphatic urethane acrylate oligomer, commercially available from Allnex Germany GmbH. Referred to hereinafter referred as E-1290. Ebecryl®5129 is a hexafunctional aliphatic urethane acrylate oligomer, commercially available from Allnex Germany GmbH. Referred to hereinafter referred as E-5129. IRR 1094 is an hexafunctional aliphatic urethane acrylate oligomer, obtained from Allnex GmbH, Germany. Ebecryl®1872 is a polyester acrylate resin, commercially available from Allnex Germany GmbH. Referred to hereinafter referred as E-1872. Ebecryl®838 is a polyester acrylate resin, commercially available from Allnex Germany GmbH. Referred to hereinafter referred as E-838. Ebecryl®3700 is an epoxy acrylate resin, commercially available from Allnex Germany GmbH. Referred to hereinafter referred as E-3700. Ebecryl®5848 is an epoxy acrylate resin based in part on renewable resources, and commercially available from Allnex Germany GmbH. Referred to hereinafter referred as E- 5848. RAS-1 is a reactive anionic surfactant of the ether sulfate type, based on a polyoxyethylene alkyl ether ammonium sulfate comprising 10 oxyethylene units, and commercially available from Adeka Co., Japan under the trade designation Reasop® SR series. RAS-2 is a reactive anionic surfactant based on a polyoxyethylene styrenated phenyl ether ammonium sulfate, and commercially available from by DKS Co. Ltd, Japan under the trade designation Hitenol® AR series. RAS-3 is a reactive anionic surfactant of the ether sulfate type, based on a polyoxyethylene alkyl ether ammonium sulfate comprising 30 oxyethylene units, and commercially available from Adeka Co., Japan under the trade designation Reasop® SR series. RNAS-C is a comparative reactive nonionic surfactant based on a polyoxyethylene alkyl ether comprising 30 oxyethylene units, and commercially available from Adeka Co., Japan under the trade designation Reasop® ER series. Maxemul®7101 is a non-ionic surfactant, commercially available from Croda, UK. Referred to hereinafter referred as M-7101. Rhodafac®RS-610/A25 is a phosphated non-reactive anionic surfactant based on a ammonium phosphate, polyoxyethylene tridecyl ether, and commercially available from Solvay. Referred to hereinafter referred as R-610. HDDA is 1,6-Hexanediol diacrylate, commercially available from Allnex GmbH, Germany.. EOEOEA is an ethoxy ethoxy ethyl acrylate, commercially available from Rahn USA Corp., under the trade designation Miramer M170. ZAY 6840 is an alkyd/acrylic-based resin obtained from Allnex GmbH, Germany. IPDI is isophorone diisocyanate, commercially available from Sigma-Aldrich. Additol®HDMAP (a.k.a photoinitiator 1173) is a photoinitiator, commercially available from Allnex Germany GmbH. Referred to hereinafter referred as A-HDMAP. Omnirad 500 is a photoinitiator commercially available from IGM Resins. Referred to hereinafter referred as OMN-500. Additol®XL250 is a is a wetting and dispersing agent, commercially available from Allnex GmbH, Germany. Referred to hereinafter referred as A-XL250. Tafigel® PUR40 is non-ionic polyurethane butyl triglycol/water, associative thickener, commercially available from Münzing. Referred to hereinafter referred as T-PUR40. Tafigel® PUR80 is non-ionic polyurethane butyl triglycol/water, associative thickener, commercially available from Münzing. Referred to hereinafter referred as T-PUR80. BYK®349 is a polyether-modified siloxane defoamer, commercially available from BYK. NIPSIL E1011 is a matting agent, commercially available from Tosoh, Japan. Referred to hereinafter referred as N-E1011. Additol®XL 250 is a an anionic wetting agent and dispersion agent phosphine commercially available from Allnex GmbH, Germany. Referred to hereinafter referred as A-XL250. Additol®TPO is a phosphine oxide based photoinitiator, commercially available from Allnex GmbH, Germany. SBC AQJ6911 is an aluminum paste, commercially available from Changzhou Yale, China. Butyl Cellosolve (BCS) is commercially available from Dow Chemicals. Propylene glycol monomethyl ether (PGME) is commercially available from Dow Chemicals. N,N-Dimethylethanolamine (DMEA) is commercially available from BASF. Examples: Example 1: General preparation of the exemplary aqueous radiation curable compositions (Ex.1 to Ex.12) and comparative examples (Ex.C1 to Ex.C5). [0111] The ethylenically unsaturated compounds (A), the reactive ionic external emulsifiers (B), which might be prediluted in water, and any additional ingredients (such as e.g. co- surfactants) are charged in a double-wall stainless steel vessel at 23°C. A first portion of water W1 is then added, and the blend that is formed is then progressively stirred at a rotation speed of 1000 rpm with a cowless propeller having a diameter of 60 mm until the phase inversion point (corresponding to a maximum of the viscosity) is achieved, thereby forming a water-based emulsion. Stirring at 1000 rpm is continued for at least 1.5 h to further reduce the particle size of the emulsion. A second portion of water W2 is then added at 23°C to the mixture at a constant flow rate during about 5 minutes using a peristaltic pump, while the cowless rotation speed is progressively decreased to 500 rpm and the temperature decreased to 23°C in order to finalize the emulsion. Table 1: Formulation of exemplary aqueous radiation curable compositions (Ex.1 to Ex.6) and comparative examples (Ex.C1 to Ex.C2). Components Ex.1 Ex.C1 Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Ex.C2 i 5 0 8 [ erall

composition).

Table 2: Formulation of exemplary aqueous radiation curable compositions (Ex.7 to Ex.12) and comparative examples (Ex.C3 to Ex.C5). Components Ex.7 Ex.C3 Ex.C4 Ex.8 Ex.9 Ex.10 Ex.11 Ex.C5 Ex.12 8 0 0 ^[

erall composition). [2] the values represented correspond to the dry content of the co-surfactant (in wt.% of the overall composition). Example 2: General preparation of the exemplary aqueous radiation curable compositions (Ex.13 and Ex.14). [0112] The ethylenically unsaturated compound (A) comprising ionic (carboxylate) functional groups is first prepared by charging the epoxy acrylate resin E-5848 and succinic acid in a double-wall stainless steel vessel at 23°C. Agitation within the reactor is started and the reactor jacket is heated at 80 °C with air sparging. The reaction is maintained for 4-7 hours while measuring partial and total acid values over time. Then, IPDI is added in the reaction mixture at 80°C and the reaction is further continued for about 2 hours. The reaction mixture is then cooled down to 50-60°C, and then the reactive ionic external emulsifier (B), which might be prediluted in water, is added under moderate agitation until completely homogenous. The neutralizing agent solution is then added at 50-60°C under moderate agitation until completely homogenous. The emulsion is thereafter made by phase inversion. For that purpose, the agitation is stopped and a first portion of water (typically one third of total water) is added before switching-on the high-shear agitation. If necessary, some additional water portion is added to reach the phase inversion point (corresponding to the highest viscosity). The maximum mixing energy is applied at that stage during 15 minutes before proceeding to the addition of the residual water in order to finalize the emulsion. The temperature is then cooled down below 35°C and add the biocide. Table 3: Formulation of exemplary aqueous radiation curable compositions (Ex.13 to Ex.14). Components [

e va ues ep ese e co espo o e dry content of the emulsifier (in wt.% of the overall composition). Example 3: Characteristics and stability of exemplary aqueous radiation curable compositions (Ex.1 to Ex.6) and comparative examples (Ex.C1 to Ex.C2). [0113] The characteristics and stability performance of the emulsions according to Ex.1 to Ex.6 and comparative examples Ex.C1 to Ex.C2 have been determined according to the test methods described hereinbefore. The exemplary compositions of Ex.1 to Ex.6 and comparative examples Ex.C1 to Ex.C2 are all based on urethane acrylates used as ethylenically unsaturated compound (A). The composition of comparative example Ex.C1 comprises a copolymerisable non-ionic surfactant, whereas the composition of comparative example Ex.C2 comprises a conventional non-ionic surfactant. The results are presented in Table 4 below. Table 4: Characteristics and stability performance of exemplary aqueous radiation curable compositions (Ex.1 to Ex.6) and comparative examples (Ex.C1 to Ex.C2). Ex.1 Ex.C1 Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Ex.C2 5 D

Example 4: Characteristics and stability of exemplary aqueous radiation curable compositions (Ex.7 to Ex.12) and comparative examples (Ex.C3 to Ex.C5). [0114] The characteristics and stability performance of the emulsions according to Ex.7 to Ex.12 and comparative examples Ex.C3 to Ex.C5 have been determined according to the test methods described hereinbefore. The exemplary compositions of Ex.7 and Ex.12, as well as comparative examples Ex.C3 to Ex.C4 are all based on urethane acrylates used as ethylenically unsaturated compound (A). The composition of comparative example Ex.C3 comprises a reactive non-ionic surfactant, whereas the composition of comparative example Ex.C4 comprises a conventional non-reactive anionic surfactant. The exemplary compositions of Ex.8 to Ex.10 are all based on polyester acrylates used as ethylenically unsaturated compound (A). The exemplary compositions of Ex.11 and comparative example Ex.C5 are based on epoxy acrylates used as ethylenically unsaturated compound (A). The composition of comparative example Ex.C5 comprises a copolymerisable non-ionic surfactant. The results are presented in Table 5 below. Table 5: Characteristics and stability performance of exemplary aqueous radiation curable compositions (Ex.7 to Ex.12) and comparative examples (Ex.C3 to Ex.C5). Ex.7 Ex.C3 Ex.C4 Ex.8 Ex.9 Ex.10 Ex.11 Ex.C5 Ex.12 4 3 0D

ND : not determined Example 5: Characteristics and stability of the exemplary aqueous radiation curable composition (Ex.12) and comparative example (Ex.C6). [0115] The characteristics and stability performance of the emulsion according to Ex.12 and comparative example Ex.C6 have been determined according to the test methods described hereinbefore. The exemplary composition of Ex.12 is as described hereinbefore. The composition of comparative example Ex.C6 has the exact same composition as that of Ex.12, at the exception that a premix comprising the ethylenically unsaturated compound (A) and reactive ionic external emulsifier (B) has not been pre-formed before water is added to the premix. In contrast, the composition of comparative example Ex.C6 has been formed by first mixing water with the reactive ionic external emulsifier (B), and then adding the ethylenically unsaturated compound (A) to the pre-formed aqueous mixture. The results are presented in Table 6 below. Table 6: Characteristics and stability performance of exemplary aqueous radiation curable composition (Ex.12) and comparative example (Ex.C6). Ex.12 Ex.C6 P i l i 1 4 A nnot be obtained.

Example 6: Characteristics and stability of the exemplary aqueous radiation curable compositions (Ex.13 to Ex.14). [0116] The characteristics and stability performance of the emulsions according to Ex.13 and Ex.14 have been determined according to the test methods described hereinbefore. The exemplary compositions of Ex.13 and Ex. 14 are prepared using an ethylenically unsaturated compound (A) further comprising ionic (carboxylate) functional groups. The results are presented in Table 7 below. Table 7: Characteristics and stability performance of exemplary aqueous radiation curable compositions (Ex.13 to Ex.14). Ex.13 Ex.14

[0117] As can be seen from the results shown in Tables 4 to 7, the aqueous radiation curable compositions according to the present disclosure (Ex.1 to Ex.14) are provided with excellent colloidal stability, even under stringent ageing conditions, as well as advantageous characteristics, in particular relatively small particle size and relatively high solid content. In contrast, it can be seen that the performance and characteristics obtained using comparative aqueous radiation curable compositions not according to the present disclosure (Ex.C1 to Ex.C6) are much less advantageous. In particular, the comparative compositions are typically deficient in terms of colloidal stability or have undesired particle size. [0118] The aqueous radiation curable compositions of Ex.13 and Ex.14 have a calculated biocarbon content of about 75%, based on the total carbon content of the compositions, and present therefore excellent sustainability characteristics. These compositions provide easy application, good drying and film formation, and deliver a wet-on-touch coating before cure. After UV curing, the resulting coatings provide a coating with a Persoz hardness of 75 seconds and a solvent resistance greater than 100 acetone double rubs. The aqueous radiation curable compositions of Ex.13 and Ex.14 are found particularly suitable as primer coatings on wood substrates to which they offers a good adhesion and substrate wetting in combination with attractive gloss and anfeuerung. They can also be used for paper impregnation. Example 7: General preparation of the exemplary coating compositions (Ex.16 to Ex.17) and

compositions, first the exemplary aqueous radiation curable composition of Ex.15 and the comparative aqueous radiation curable composition of Ex.C8 have to be prepared. The exemplary composition of Ex.15 and the comparative composition of Ex.C8 are prepared according to the general procedure described in Example 1 above and based on the formulations described in Table 8 below. Table 8: Formulation of exemplary aqueous radiation curable composition (Ex.15) and comparative composition (Ex.C8). Components Ex.15 Ex.C8 i [ he dry content of the emulsifier (in wt.% of the overall

composition). [0120] An exemplary clear coating composition according to Ex.16 and a comparative clear coating according to Ex.C7 are further prepared based on the formulations described in Table 9 below. Table 9: Formulation of exemplary clear coating composition (Ex.16) and comparative clear coating composition (Ex.C7). Components

[0121] The coating formulations are applied on a polycarbonate substrate using a bar coater, thereby obtaining 50 micrometers wet coating layers. The applied formulations are dried for 6 minutes at 50°C, and the coatings are cured under UV lights at a cure speed of 5 m/min using 80 Watt/cm2 Hg lamps. The cured coatings are then used for further testing. [0122] An exemplary metallic coating composition according to Ex.17 and a comparative metallic coating according to Ex.C9 are further prepared based on the formulations described in Table 10 below. Table 10: Formulation of the exemplary metallic coating composition (Ex.17) and the comparative metallic coating composition (Ex.C9). Components Ex 17 ExC9

[0123] The metallic coating formulations are applied on a plastic substrate (PC or ABS) using a spray coater. The applied formulations are dried for 10 minutes at 60°C, thereby obtaining a dry film thickness (DFT) of about 10 micrometers. The coatings are subsequently cured under UV lights at a cure speed of 5 m/min using 80 Watt/cm2 Hg lamps. The cured coatings are then used for further testing. Example 8: Performance attributes of the exemplary clear coating (Ex.16) and the comparative clear coating (Ex.C7). [0124] Various performance attributes of the exemplary clear coating composition (Ex.16) and the comparative clear coating (Ex.C7), in particular adhesion to polycarbonate substrate, hot water resistance and hydrolysis resistance, have been determined according to the test methods described hereinbefore. The results are presented in Table 11 below. Table 11: Performance attributes of the exemplary clear coating (Ex.16) and the comparative clear coating (Ex.C7). Ex.16 Ex.C7

[0125] As can be seen from the results shown in Table 11, a clear coating according to the present disclosure (Ex.16) is provided with excellent performance attributes as regard to adhesion to polycarbonate substrate, hot water resistance and hydrolysis resistance, even under stringent conditions. In contrast, it can be seen that the performance and characteristics obtained using a comparative clear coating not according to the present disclosure (Ex.C7) are less advantageous. In particular, the comparative clear coating is typically deficient in terms of hot water resistance and hydrolysis resistance. Example 9: Performance attributes of the exemplary metallic coating (Ex.17) and the comparative metallic coating (Ex.C9). [0126] Various performance attributes of the exemplary metallic coating (Ex.17) and the comparative metallic coating (Ex.C9), in particular adhesion to polycarbonate and ABS substrates, hot water resistance, scratch resistance and gloss level, have been determined according to the test methods described hereinbefore. The results are presented in Table 12 below. Table 12: Performance attributes of the exemplary metallic coating (Ex.17) and the comparative metallic coating (Ex.C9). Ex.17 Ex.C9

[0127] As can be seen from the results shown in Table 12, a metallic coating according to the present disclosure (Ex.17) is provided with excellent performance attributes as regard to adhesion to polycarbonate and ABS substrates, hot water resistance, scratch resistance and gloss level. In contrast, it can be seen that the performance and characteristics obtained using a comparative metallic coating not according to the present disclosure (Ex.C9) are less advantageous. In particular, the comparative metallic coating is typically deficient in terms of hot water resistance, scratch resistance and gloss level.

Claims

CLAIMS 1. An aqueous radiation curable composition obtained by: a) mixing at least one ethylenically unsaturated compound (A) with at least one reactive ionic external emulsifier (B), wherein the reactive ionic external emulsifier (B) is represented by the general formula (I): D-O-(R1O)n-X (I) wherein: D is a moiety comprising an ethylenically unsaturated group (E); R1 is a linear or branched C2-C6 alkylene group; X is an ionic moiety; and n is in a range from 4 to 50, thereby obtaining a premix; and b) adding water to the premix until a phase inversion occurs.

2. A composition according to claim 1, wherein n is no greater than 50, no greater than 45, no greater than 40, no greater than 35, no greater than 30, no greater than 25, no greater than 20, no greater than 15, or even no greater than 10.

3. A composition according to any one of claim 1 or 2, wherein the ethylenically unsaturated group (E) is selected from the group consisting of allyl group, vinyl group, propenyl group, allyloxy, vinyloxy, propenyloxy, allyloxymethyl vinyloxymethyl, propenyloxymethyl, (meth)acryloyl, and any combinations or mixtures thereof.

4. A composition according to any one of the preceding claims, wherein the ionic moiety (X) is an anionic moiety preferably selected from the group consisting of sulfate groups, sulphonate groups, phosphate groups, phosphonate groups, phosphite groups, and any combinations or mixtures thereof.

5. A composition according to any one of the preceding claims, wherein the moiety (D) is selected from the group of linear or branched alkyl groups, linear or branched aryl groups, linear or branched alkyl ether groups, linear or branched aryl ether groups, additionally substituted with the ethylenically unsaturated group (E).

6. A composition according to any one of the preceding claims, wherein the moiety (D) is represented by the general formula (II): R3-O-CH₂-CHR2- (II) wherein: R2 is : -CH2-O-CH2-CH=CH2; R3 is a linear or branched (C8-C14) alkyl group, in particular a linear (C10- C₁₂) alkyl group; or by the general formula (III): R³-CH₂-CHR²- (III) wherein: R2 is : -CH₂-O-CH₂-CH=CH₂; R3 is a linear or branched (C8-C14) alkyl group, in particular a linear (C10- C₁₂) alkyl group; or by the general formula (IV):

wherein: (E) is: -CH=CR⁴-CH₃; or -CH 4 2-CR =CH2 wherein R4 is H or a linear or branched (C₁-C₆) alkyl group; (R5) is:

and wherein m1 and m2 are independently 1 or 2.

7. A composition according to any one of the preceding claims, wherein the reactive ionic external emulsifier (B) is selected from the group consisting of (ethylenically unsaturated derivatives of) polyoxyethylene alkyl ether sulfate (ammonium) salts, and polyoxyethylene aryl ether sulfate (ammonium) salts, in particular polyoxyethylene styrenated phenyl ether sulfate (ammonium) salts.

8. A composition according to any one of the preceding claims, wherein the reactive ionic external emulsifier (B) is selected from the group consisting of: ; and wherein:

m3 is 1 or 2; and R3 and n are as defined in claims 1 and 6.

9. A composition according to any one of the preceding claims, wherein the ethylenically unsaturated compound (A) further comprises ionic functional groups, that are in particular at least partly neutralized by a neutralizing agent (C).

10. A composition according to claim 9, wherein the ionic functional groups are acidic functional groups, in particular selected from the group consisting of carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, and any combinations or mixtures thereof.

11. A composition according to any one of the preceding claims, which has a particle size no greater than 800 nm, no greater than 600 nm, no greater than 400 nm, no greater than 350 nm, no greater than 300 nm, no greater than 250 nm, no greater than 200 nm, no greater than 150 nm, no greater than 100 nm, or even no greater than 80 nm, when determined by DLS measurements according to the test method described in the experimental section.

12. A composition according to any one of the preceding claims, which has a solid content greater than 30 wt.%, greater than 35 wt.%, greater than 40 wt.%, greater than 45 wt.%, greater than 50 wt.%, greater than 55 wt.%, greater than 60 wt.%, or even greater than 65 wt.%, when determined by gravimetric method according to the test method described in the experimental section.

13. A coating composition comprising an aqueous radiation curable composition according to any one of the preceding claims.

14. A process for the manufacturing of an aqueous radiation curable composition, comprising the steps of: a) mixing at least one ethylenically unsaturated compound (A), as described in any one of claims 1 to 10, with at least one reactive ionic external emulsifier (B), as described in any one of claims 1 to 8, thereby obtaining a premix; and b) adding water to the premix until a phase inversion occurs.

15. Use of an aqueous radiation curable composition or a coating composition according to any one of claims 1 to 13 in computer, communication and consumer electronics, dual cure applications, coating applications, composite applications, three dimensional (3D) applications, (inkjet) printing applications, adhesive applications, paper impregnation applications or thick pigmented systems.