Water-based radiation hardening components

Abstract

1. An aqueous radiation-curable composition comprising: a) 45 to 80% by weight of at least one (polymerizable) (water-insoluble) ethylenically unsaturated compound (A); and b) 20 to 55% by weight of at least one (polymerizable) ethylenically unsaturated polyurethane polymer (B), comprising: i. at least one polyisocyanate compound (i); ii. at least one polymerizable polyol (ii); iii. at least one (non-polymerizable) hydrophilic compound comprising at least one reactive group capable of reacting with an isocyanate group and at least one group capable of dispersing the polyurethane polymer (B) in an aqueous medium, either directly or after reaction with a neutralizing agent, to provide a salt. an ethylenically unsaturated polyurethane polymer (B) obtained from the reaction of (A), (i), (ii), (iii), (iv), (iii), (iv), (iv) at least one compound (iv) comprising at least one (essentially one) reactive group capable of reacting with an isocyanate group and further comprising at least one ethylenically unsaturated group, and v. optionally at least one (non-polymerizable) compound (v) comprising at least one (essentially one) reactive group capable of reacting with an isocyanate group, wherein compounds (A), (i), (ii), (iii), (iv), and (v) are all different from one another, and the weight percentages are based on the total dry content of the radiation curable composition.

Description

[Technical Field]

[0001] The present invention relates to an aqueous radiation-curable composition and a coating composition comprising said aqueous radiation-curable composition. [Background technology]

[0002] Plastic coatings are an important and high-growth segment of the coatings industry, targeting challenging requirements for advanced surface finishing techniques that encompass aesthetics as well as additional protective and functional features. Coatings in so-called 3C applications, including computers, communications, and consumer electronics, are particularly challenging to formulate as they utilize a variety of low surface energy substrates, including, for example, polycarbonates and additional synthetic polymers or fibers, which are notoriously difficult to bond to.

[0003] As stricter VOC emission regulations are implemented worldwide, the demand for low-VOC coating solutions is rapidly increasing. In this context, waterborne radiation-curable coating compositions are becoming increasingly popular as an alternative to solvent-based resins. However, waterborne radiation-curable coating compositions known in the art are known to be limited in their use in difficult plastic applications, particularly due to poor adhesion performance.

[0004] Partial solutions are described, for example, in U.S. Patent Application Publication No. 2020 / 0181451 (Su et al.). There remains a need for low-VOC radiation-curable compositions that at least partially overcome the above-mentioned shortcomings without disputing the technical advantages associated with solutions known in the art. Summary of the Invention [Means for solving the problem]

[0005] According to one aspect, the present disclosure provides an aqueous radiation curable composition comprising: a) 45 to 80% by weight of at least one ethylenically unsaturated compound (A); b) 20 to 55% by weight of at least one ethylenically unsaturated polyurethane polymer (B), i. at least one polyisocyanate compound (i); ii. at least one polymerizable polyol (ii); iii. at least one hydrophilic compound (iii) comprising at least one reactive group capable of reacting with an isocyanate group and at least one group capable of dispersing the polyurethane polymer (B) in an aqueous medium, either directly or after reaction with a neutralizing agent, to give a salt; iv. at least one compound (iv) containing at least one reactive group capable of reacting with an isocyanate group and further containing at least one ethylenically unsaturated group; and v. optionally, at least one compound (v) comprising at least one reactive group capable of reacting with an isocyanate group, and The present invention relates to an aqueous radiation curable composition wherein compounds (A), (i), (ii), (iii), (iv), and (v) are all different from one another, and the weight percentages are based on the total dry content of the radiation curable composition.

[0006] According to another aspect, the present disclosure relates to a coating composition comprising the above-described aqueous radiation-curable composition.

[0007] In yet another aspect of the present disclosure, there is provided a method for producing an aqueous radiation curable composition, comprising: a) mixing and reacting compounds (i), (ii), (iii), and optionally compound (vi) as described above; b) reacting the product of step a) with compound (iv) described above, thereby obtaining an ethylenically unsaturated polyurethane polymer (B); c) adding at least one ethylenically unsaturated compound (A) as described above; d) optionally reacting compound (iii) with a neutralizing agent to convert the hydrophilic group provided by compound (iii) into an anionic salt; e) dispersing the ethylenically unsaturated polyurethane polymer (B) obtained in step b) or optional step d) in an aqueous medium; f) optionally reacting the ethylenically unsaturated polyurethane polymer (B) obtained in step e) with compound (v) as described above.

[0008] According to yet another aspect, the present disclosure relates to the use of the above-described waterborne radiation curable compositions or coating compositions in computer, communications, and consumer electronics applications, dual cure applications, or thick pigmented systems. DETAILED DESCRIPTION OF THE INVENTION

[0009] According to a first aspect, the present disclosure provides an aqueous radiation curable composition comprising: a) 45 to 80% by weight of at least one ethylenically unsaturated compound (A); b) 20 to 55% by weight of at least one ethylenically unsaturated polyurethane polymer (B), i. at least one polyisocyanate compound (i); ii. at least one polymerizable polyol (ii); iii. at least one hydrophilic compound (iii) comprising at least one reactive group capable of reacting with an isocyanate group and at least one group capable of dispersing the polyurethane polymer (B) in an aqueous medium, either directly or after reaction with a neutralizing agent, to give a salt; iv. at least one (polymerizable) compound (iv) containing at least one reactive group capable of reacting with an isocyanate group and further containing at least one ethylenically unsaturated group, and v. optionally, at least one (non-polymerizable) compound (v) comprising at least one (essentially one) reactive group capable of reacting with an isocyanate group, and The present invention relates to an aqueous radiation curable composition wherein compounds (A), (i), (ii), (iii), (iv), and (v) are all different from one another, and the weight percentages are based on the total dry content of the radiation curable composition.

[0010] In the context of the present disclosure, it has surprisingly been found that the above-described aqueous radiation-curable compositions possess excellent colloidal stability even under severe aging conditions, as well as advantageous formulation flexibility.

[0011] Quite surprisingly, it has been found that the above-described waterborne radiation curable compositions are particularly suitable for forming coatings with excellent properties and performance attributes with respect to adhesion to difficult-to-bond plastic substrates (specifically polycarbonate, acrylonitrile butadiene styrene, and any combination thereof), hot water resistance, hydrolysis resistance, visual aesthetics in complex formulations (such as, for example, metallic or matte formulations), abrasion resistance, stain resistance, and low VOC characteristics.

[0012] Without wishing to be bound by theory, these superior properties and attributes are believed to be specifically due to the use of a specific combination of (a) at least one ethylenically unsaturated compound (A) and (b) at least one ethylenically unsaturated polyurethane polymer (B) obtained as described above, wherein compound (A) and polyurethane polymer (B) are included in the radiation curable composition in the specific ranges detailed above.

[0013] More specifically, it is believed that this specific combination of ingredients in the particular weight ranges detailed above contributes to providing an aqueous radiation curable composition with advantageous properties, specifically relatively small particle size and excellent viscosity characteristics, resulting in coatings with the excellent properties and performance attributes detailed above.

[0014] Without wishing to be further bound by theory, it is further believed that the polyurethane polymer (B) obtained as described above, when used in combination with at least one ethylenically unsaturated compound (A) in the range of 45 to 80% by weight based on the total dry content of the radiation-curable composition, formally acts as an effective internal stabilizer (or emulsifier) ​​for a relatively high proportion of the ethylenically unsaturated compound (A), and has a beneficial effect on the stability of the resulting aqueous radiation-curable composition.

[0015] This is a particularly surprising and groundbreaking finding considering that aqueous compositions containing more than 30% by weight of such ethylenically unsaturated compounds (A) are generally recognized to have poor stability and poor aging resistance.

[0016] The specific ethylenically unsaturated polyurethane polymer (B) also allows for excellent design flexibility, thus making it possible to obtain aqueous radiation-curable compositions and coatings obtained therefrom with finely tuned characteristics and excellent formulation flexibility. Furthermore, the presence of ethylenic unsaturation in the structure of the polyurethane polymer (B) is also believed to prevent (or at least substantially reduce) the presence of free stabilizers (or emulsifiers) after polymerization. The presence of such free or mobile stabilizers after curing is known to actually adversely affect various characteristics of the resulting coating, in particular its (hot) water resistance and hydrolysis resistance, and thus negatively impact the visual aesthetics due to the unwanted migration of these free stabilizers through the coating layer to its outer surface.

[0017] As such, the aqueous radiation curable compositions of the present disclosure are well suited for forming coatings for use in 3C applications.

[0018] The aqueous radiation-curable composition of the present disclosure comprises, as a first component, at least one (polymerizable) ethylenically unsaturated compound (A) in an amount of 45 to 80% by weight based on the total dry content of the radiation-curable composition.

[0019] In one advantageous embodiment, the aqueous radiation curable composition comprises more than 45 wt.%, more than 50 wt.%, more than 55 wt.%, more than 60 wt.%, more than 65 wt.%, more than 70 wt.%, or even more than 75 wt.% of at least one ethylenically unsaturated compound (A), based on the total dry content of the radiation curable composition.

[0020] In another advantageous embodiment of the present disclosure, the aqueous radiation curable composition comprises 45 to 75 wt. %, 45 to 70 wt. %, or even 50 to 70 wt. % of at least one ethylenically unsaturated compound (A), based on the total dry weight content of the radiation curable composition.

[0021] The ethylenically unsaturated compound (A) used herein is not particularly limited. Suitable ethylenically unsaturated compounds (A) used herein will be easily identified by those skilled in the art in light of the present disclosure.

[0022] As used herein, compound (A) contains at least one, typically at least two, polymerizable ethylenically unsaturated groups per molecule, also referred to herein as "ethylenically unsaturated functional group" or "ethylenically unsaturated group." Throughout this disclosure, "polymerizable ethylenically unsaturated group" refers to a carbon-carbon double bond capable of undergoing radical polymerization under the influence of irradiation. Examples of such groups are (meth)acryloyl, (meth)acrylamide, vinyl, vinyl ether, allyl, styrenyl, methylstyrenyl, maleyl, or fumaryl functional groups. As used herein, the ethylenically unsaturated group is generally selected from (meth)acryloyl and / or allyl groups, preferably (meth)acryloyl groups, and more preferably acryloyl groups. In this disclosure, the term "(meth)acryloyl" should be understood to encompass both acryloyl and methacryloyl groups or derivatives thereof, as well as mixtures thereof.

[0023] The compound (A) used in the present disclosure can be a monomer, an oligomer, and / or a polymerizable ethylenically unsaturated compound. Blends of monomers, oligomers, and / or polymerizable ethylenically unsaturated compounds (A) can also be used.

[0024] Typically, the ethylenically unsaturated compound (A) is monomeric or oligomeric in nature. Advantageously, the compound (A) used herein is oligomeric. Typical monomeric compounds (A) have a weight average molecular weight (M) in the range of 50 to 300 g / mol, 100 to 250 g / mol, or even 100 to 200 g / mol, as measured by conventional gel permeation chromatography (GPC) techniques. w Typical oligomeric compounds (A) have a weight average molecular weight (M) in the range of 300 to 20,000 daltons, 500 to 15,000 daltons, 500 to 10,000 daltons, or even 800 to 5,000 daltons, as measured by conventional gel permeation chromatography (GPC) techniques. w )

[0025] According to an advantageous embodiment, the at least one ethylenically unsaturated compound (A) used herein has a weight average molecular weight (Mw) of at most 3000 g / mol, at most 2500 g / mol, at most 2000 g / mol, at most 1500 g / mol, at most 1200 g / mol, at most 1000 g / mol, at most 800 g / mol, at most 600 g / mol, at most 500 g / mol, at most 400 g / mol, at most 300 g / mol, or even at most 200 g / mol.

[0026] In another advantageous embodiment, the ethylenically unsaturated compound (A) as used herein is a water-insoluble compound. In the present disclosure, the term "water-insoluble compound" refers to an ethylenically unsaturated compound that is neither self-emulsifying nor self-dispersing, but forms an emulsion or dispersion in water or an aqueous solution in the presence of one or more reactive ionic external emulsifiers (B) as defined above. More specifically, according to this advantageous embodiment of the present disclosure, the compound (A) is a non-self-dispersing, non-self-emulsifying, non-water-dilutable compound. Typically, the ethylenically unsaturated compound (A) as used herein is not a self-dispersing compound. In the present disclosure, the term "self-dispersing compound" refers to 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. In the present disclosure, the term "self-emulsifying compound" refers to 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. "Stable" as used herein refers to the substantial absence of coalescence (droplets) or aggregation (particles) that would result in phase separation, creaming, or sedimentation of a heterogeneous system after 2 days or more, typically 4 days or more, and preferably 10 days at 60°C. Typically, compound (A) as used herein is not a water-dilutable compound. In this disclosure, "water-dilutable compound" refers to a compound that, when mixed with water in a concentration range of 5 to 75% by weight based on the total mass of water and the compound, allows the formation of a homogeneous single-phase mixture, in the absence of an emulsifier.

[0027] In typical embodiments, the ethylenically unsaturated compound (A) of the present disclosure has a solubility at 25° C. of less than 50 g / L, less than 40 g / L, less than 30 g / L, less than 25 g / L, less than 20 g / L, less than 10 g / L, less than 5 g / L, or even less than 1 g / L.

[0028] The ethylenically unsaturated compound (A) is 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 meq / 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 / g of solid material.

[0029] In exemplary embodiments, the ethylenically unsaturated compound (A) used herein contains 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.

[0030] Advantageously, compound (A) combines the functionality and degree of unsaturation indicated above. Specifically, preferred compounds (A) used 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 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.

[0031] According to an exemplary embodiment, the ethylenically unsaturated compound (A) used in the present disclosure is specifically a (meth)acrylated compound 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 polyacryl (meth)acrylates (A6). Exemplary ethylenically unsaturated compounds (A) used herein are extensively detailed in U.S. Patent Application No. 2014 / 0377466 (Tielemans et al.), the contents of which are incorporated herein by reference in their entirety.

[0032] According to one particular aspect of the present disclosure, the ethylenically unsaturated compound (A) used herein is selected from the group consisting of urethane (meth)acrylates (A1), polyester (meth)acrylates (A2), epoxy (meth)acrylates (A3), (meth)acrylic (meth)acrylates (A4), and any combination or mixture thereof.

[0033] In a preferred embodiment, the ethylenically unsaturated compound (A) is selected from the group consisting of urethane (meth)acrylates (A1), which have surprisingly been found to provide outstanding adhesive performance to difficult-to-bond plastic substrates, particularly those used in 3C applications, such as polycarbonate and acrylonitrile butadiene styrene, and any combination thereof.

[0034] In another preferred embodiment, the ethylenically unsaturated compound (A) is selected from the group of (meth)acrylated compounds that do not contain a reactive group capable of reacting with an isocyanate group, in particular from the group of (meth)acrylated compounds that contain at least two (meth)acrylic groups.

[0035] In a particularly preferred embodiment, the ethylenically unsaturated compound (A) is selected from the group consisting of hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, di-pentaerythritol hexa(meth)acrylate, and their (poly)ethoxylated and / or (poly)propoxylated equivalents, as well as any combination or mixture thereof.

[0036] In an alternative embodiment, the ethylenically unsaturated compound (A) is selected from the group of (meth)acrylated compounds comprising reactive groups capable of reacting with isocyanate groups, in particular from the group of (meth)acrylated compounds comprising at least two (meth)acrylic groups and one or more additional functional groups, in particular hydroxyl functional groups, which additional functional groups typically provide additional features to the aqueous radiation-curable composition.

[0037] In another beneficial aspect of the aqueous radiation-curable composition of the present disclosure, the ethylenically unsaturated compound (A) used herein is at least partially bio-based, specifically having a bio-based content of more than 10%, more than 20%, more than 40%, more than 60%, or even more than 80% by weight of the total carbon content of the ethylenically unsaturated compound (A), when the bio-based content is determined according to the ASTM D6866 standard test method. Exemplary bio-based ethylenically unsaturated compounds (A) used herein, and methods for obtaining them, are also broadly described in WO 2022 / 128462 (Tielemans), the contents of which are incorporated herein by reference in their entirety.

[0038] The aqueous radiation-curable composition of the present disclosure comprises, as a second component, at least one (polymerizable) ethylenically unsaturated polyurethane polymer (B) obtained from the reaction of at least one polyisocyanate compound (i), which is intended to refer to an organic compound containing at least two isocyanate groups.

[0039] The polyisocyanate compound (i) used herein is not particularly limited. A suitable polyisocyanate compound (i) used herein will be easily identified by a person skilled in the art in light of the present disclosure. The polyisocyanate compound (i) typically contains 3 or less isocyanate groups. Advantageously, the polyisocyanate compound (i) is a diisocyanate.

[0040] In a typical embodiment, the at least one polyisocyanate compound (i) is selected from aliphatic and cycloaliphatic polyisocyanates, specifically diisocyanates. Examples of aliphatic and cycloaliphatic polyisocyanates are 1,6-diisocyanatohexane (HDI), 1,1'-methylenebis[4-isocyanatocyclohexane] (H12MDI), and 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane (isophorone diisocyanate, IPDI). Aliphatic polyisocyanates containing more than two isocyanate groups are derivatives of the above-mentioned diisocyanates, such as 1,6-diisocyanatohexane biuret and isocyanurate. Examples of aromatic polyisocyanates include 1,4-diisocyanate benzene (BDI), 2,4-diisocyanate toluene (TDI), 1,1'-methylenebis[4-isocyanate benzene] (MDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), 1,5-naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), and p-phenylene diisocyanate (PPDI). 1,1'-methylenebis[4-isocyanate cyclohexane] (H12MDI), isophorone diisocyanate (IPDI), and tetramethylxylylene diisocyanate (TMXDI) are particularly preferred.

[0041] The amount of polyisocyanate compound (i) used in the synthesis of the ethylenically unsaturated polyurethane polymer (B) is typically comprised in the range of 5 to 60 wt%, 10 to 50 wt%, 15 to 40 wt%, or even 20 to 30 wt%, based on the total weight of the at least one ethylenically unsaturated polyurethane polymer (B).

[0042] The ethylenically unsaturated polyurethane polymer (B) is obtained from the reaction of at least one further polymerizable polyol (ii). In the context of the present disclosure, the term "polymerizable polyol" refers to a polymer comprising at least two hydroxyl groups and a polymerizable backbone, the polymerizable backbone typically having a weight average molecular weight (M) of at least 500 g / mol. w)

[0043] The polymerizable polyol (ii) used herein is not particularly limited. Suitable polymerizable polyols (ii) will be easily identified by those skilled in the art in light of the present disclosure. Advantageously, the polymerizable polyol (ii) can be selected from high molecular weight polyols and low molecular weight polyols. Advantageously, the polymerizable polyol (ii) is selected from high molecular weight polyols.

[0044] In an exemplary embodiment, the at least one polymerizable polyol (ii) has a weight average molecular weight (M) of greater than 500 g / mol, greater than 600 g / mol, greater than 700 g / mol, greater than 800 g / mol, greater than 900 g / mol, or even greater than 1000 g / mol. w )

[0045] More typically, the at least one polymerizable polyol (ii) has a weight average molecular weight (M) of 5000 g / mol or less, 4000 g / mol or less, 3000 g / mol or less, 2000 g / mol or less, 1500 g / mol or less, or even 1000 g / mol or less. W )

[0046] According to an exemplary embodiment, the at least one polymerizable polyol (ii) is selected from the group consisting of polycarbonate polyols, polyester polyols, polyether polyols, fatty dimer diols, polybutadiene polyols, polyacrylate polyols, silicone polyols, and any combination or mixture thereof.

[0047] Suitable polyacrylate polyols include those prepared by radical polymerization of (meth)acrylic and / or (meth)acrylamide monomers initiated by a thermal radical initiator in the presence of a hydroxylated mercaptan, followed by end-group transesterification with a short-chain diol such as 1,4-butanediol.

[0048] Suitable polyether polyols include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, or block copolymers thereof. Suitable fatty dimer diols are obtained from the hydrogenation of dimer acids, preferably those containing 36 carbon atoms.

[0049] In an advantageous embodiment, the at least one polymerizable polyol (ii) is selected from polycarbonate polyols, polyester polyols, and any combination or mixture thereof.

[0050] Suitable polyester polyols are, in particular, those obtained from the ring-opening polymerization of lactones, as well as the hydroxyl-terminated reaction products of polyhydric, preferably dihydric, alcohols with polycarboxylic acids, preferably dicarboxylic acids, or their corresponding anhydrides. The polycarboxylic acids that can be used to form these polyester polyols can be aliphatic, cycloaliphatic, aromatic, and / or heterocyclic, and can be substituted, saturated, or unsaturated. Polyhydric alcohols that can be used to prepare the polyester polyols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, dibutylene glycol, 2-methyl-1,3-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, an ethylene oxide or propylene oxide adduct of bisphenol A, or hydrogenated bisphenol A. Polyols such as glycerin, trimethylolethane, trimethylolpropane, di-trimethylolethane, di-trimethylolpropane, and pentaerythritol may also be used. Particularly advantageous polyester polyols are those made from the polycondensation of neopentyl glycol with adipic acid and / or isophthalic acid.

[0051] According to a particularly advantageous embodiment of the present disclosure, the at least one polymerizable polyol (ii) is selected from the group of polycarbonate polyols, in particular those obtained by reacting diols (such as ethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, or tetraethylene glycol) with phosgene, dialkyl carbonates (such as dimethyl carbonate), diaryl carbonates (such as diphenyl carbonate), or cyclic carbonates (such as ethylene and / or propylene carbonate). Particularly advantageous polycarbonate polyols are aliphatic polycarbonate diols, in particular those sold by Covestro under the trade name Desmophen® series.

[0052] The use of polycarbonate polyols has been found to provide outstanding adhesive performance to difficult-to-bond plastic substrates, particularly those used in 3C applications, such as polycarbonate and acrylonitrile butadiene styrene, and any combination thereof.

[0053] The amount of polymerizable polyol (ii) used in the synthesis of the ethylenically unsaturated polyurethane polymer (B) is typically comprised in the range of 2 to 50 wt%, 3 to 30 wt%, 5 to 25 wt%, or even 7 to 25 wt%, based on the total weight of the at least one ethylenically unsaturated polyurethane polymer (B).

[0054] The ethylenically unsaturated polyurethane polymer (B) is obtained from the reaction of at least one further (non-polymerizable) hydrophilic compound (iii) comprising at least one reactive group capable of reacting with an isocyanate group and at least one group capable of making the polyurethane polymer (B) dispersible in an aqueous medium, either directly or after reaction with a neutralizing agent, to give a salt.

[0055] The hydrophilic compound (iii) used herein is not particularly limited as long as it satisfies the above requirements. Suitable hydrophilic compounds (iii) will be easily identified by those skilled in the art in light of the present disclosure. The hydrophilic compound (iii) is typically a polyol, specifically a diol, containing a functional group that can exhibit ionic or non-ionic hydrophilic properties.

[0056] In one advantageous embodiment, the at least one hydrophilic compound (iii) is a non-polymerizable compound (in particular a compound that does not contain any ethylenically unsaturated groups), in particular chosen from the group of polyols comprising one or more anionic salt groups, such as carboxylate and sulfonate salt groups, or acid groups that can be converted into anionic salt groups, such as carboxylate or sulfonate groups.

[0057] In a preferred embodiment, at least one hydrophilic compound (iii) has the general formula (HO) x R(COOH) y wherein R represents a straight or branched chain hydrocarbon residue having 1 to 12 carbon atoms, and x and y are independently integers of 1 to 3. Examples of these hydroxycarboxylic acids include citric acid, malic acid, lactic acid, and tartaric acid. Particularly preferred hydroxycarboxylic acids are α,α-dimethylolalkanoic acids, where x=2 and y=1 in the above general formula.

[0058] In a more preferred embodiment, the at least one hydrophilic compound (iii) is selected from the group consisting of 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid.

[0059] The amount of hydrophilic compound (iii) used in the synthesis of the ethylenically unsaturated polyurethane polymer (B) is typically comprised in the range of 1 to 25 wt%, 2 to 20 wt%, 3 to 15 wt%, or even 4 to 10 wt%, based on the total weight of the at least one ethylenically unsaturated polyurethane polymer (B).

[0060] The ethylenically unsaturated polyurethane polymer (B) results from the reaction of at least one further (polymerizable) compound (iv) which comprises at least one (essentially one) reactive group capable of reacting with an isocyanate group and further comprises at least one ethylenically unsaturated group.

[0061] The compound (iv) used in this specification is not particularly limited as long as it satisfies the above requirements. Suitable compounds (iv) will be easily identified by those skilled in the art in light of the present disclosure.

[0062] Advantageously, at least one compound (iv) comprises essentially one reactive group capable of reacting with an isocyanate group and further comprises at least one, in particular at least two, ethylenically unsaturated groups. Typically, compound (iv) comprises at least one nucleophilic functional group capable of reacting with an isocyanate group.

[0063] In a more advantageous embodiment, the reactive group of at least one compound (iv) comprises a hydroxyl group and the ethylenically unsaturated group of at least one compound (iv) is a (meth)acrylic group. (Meth)acryloyl mono-hydroxy compounds, more particularly poly(meth)acryloyl mono-hydroxy compounds, are preferred.

[0064] Useful compounds (iv) include esterification products of aliphatic and / or aromatic polyols with (meth)acrylic acid having a residual average hydroxyl functionality of about 15. Partially esterified products of (meth)acrylic acid with trihydric, tetrahydric, pentahydric, or hexahydric polyols or mixtures thereof are preferred. In this context, it is also possible to use reaction products of such polyols with ethylene oxide and / or propylene oxide or mixtures thereof, or reaction products of such polyols with lactones that add to these polyols in a ring-opening reaction. Examples of suitable lactones are γ-butyrolactone, specifically δ-valerolactone and ε-caprolactone. These modified or unmodified polyols are usually partially esterified with acrylic acid, methacrylic acid, or mixtures thereof until the desired residual hydroxyl functionality is reached. Compounds (iv) obtained from the reaction of (meth)acrylic acid with aliphatic, cycloaliphatic, or aromatic compounds having epoxy functionality along with at least one (meth)acrylic functionality can also be used. Other suitable compounds are (meth)acrylic acid esters with linear and branched polyols in which at least one hydroxy functionality remains free, such as hydroxyalkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group. Preferred molecules in this class are hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate.

[0065] In a preferred embodiment, the at least one compound (iv) is selected from the esterification products of aliphatic and / or aromatic polyols with (meth)acrylic acid having a residual average hydroxyl functionality of about 1.

[0066] In a more preferred embodiment, the at least one compound (iv) is selected from the group of poly(meth)acryloyl mono-hydroxy compounds, in particular from the group consisting of glycerol di(meth)acrylate, trimethylolpropane di(meth)acrylate, glycerol di(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and their (poly)ethoxylated and / or (poly)propoxylated equivalents, as well as any combination or mixture thereof. Even more preferably, the at least one compound (iv) is selected from the group consisting of pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and any combination or mixture thereof.

[0067] The amount of compound (iv) used in the synthesis of the ethylenically unsaturated polyurethane polymer (B) is typically comprised in the range of 10 to 60 wt%, 20 to 60 wt%, 15 to 55 wt%, 20 to 55 wt%, or even 30 to 50 wt%, based on the total weight of the at least one ethylenically unsaturated polyurethane polymer (B).

[0068] The ethylenically unsaturated polyurethane polymer (B) may be obtained from the reaction of at least one further optional (non-polymerizable) compound (v) containing at least one reactive group capable of reacting with an isocyanate group. The compound (v) used herein is not particularly limited and will be easily identified by those skilled in the art in light of the present disclosure.

[0069] In a typical embodiment, at least one compound (v) is a non-polymerizable compound (specifically, a compound that does not contain any ethylenically unsaturated groups) that contains at least one reactive group capable of reacting with an isocyanate group.

[0070] Typically, the compound (v) used herein contains at least one nucleophilic functional group capable of reacting with an isocyanate group. More typically, the reactive group capable of reacting with an isocyanate group can react with the free (or residual) isocyanate end group of the ethylenically unsaturated polyurethane polymer (B), thereby resulting in chain extension of the polyurethane polymer (B). Therefore, the compound (v) used herein can also be referred to as a chain extender.

[0071] In the context of the present disclosure, it has surprisingly been found that the chain-extended ethylenically unsaturated polyurethane polymer (B) resulting from the use of at least one compound (v) leads to aqueous radiation-curable compositions with improved colloidal stability, especially for aqueous compositions having a relatively high content of ethylenically unsaturated compound (A), for example typically greater than 55 wt. %, greater than 60 wt. %, greater than 65 wt. %, or even 70 wt. %, based on the total dry weight content of the radiation-curable composition.

[0072] Without wishing to be bound by theory, it is believed that the improved colloidal stability is promoted by ensuring better compatibility with the chain-extended ethylenically unsaturated polyurethane polymer (B) with a relatively high content of ethylenically unsaturated compound (A) present in the aqueous radiation-curable composition, thereby improving the aging stability of the resulting composition.

[0073] The chain-extended ethylenically unsaturated polyurethane polymer (B) is also believed to favorably influence the abrasion resistance of coatings obtained from the corresponding aqueous radiation-curable compositions.

[0074] In an advantageous embodiment, the at least one compound (v) is selected from the group of active amino group-containing compounds. More advantageously, the at least one compound (v) used herein is selected from the group of (water-soluble) aliphatic, cycloaliphatic, aromatic or heterocyclic primary or secondary polyamines or hydrazines having up to 60, in particular up to 12, carbon atoms.

[0075] In a more advantageous embodiment, the at least one compound (v) is selected from the group consisting of meta-xylylenediamine, ethylenediamine, diethylenetriamine, piperazine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 2-methylpentamethylenediamine, triethylenetriamine, isophoronediamine (or 1-amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane), bis(4-aminocyclohexyl)methane, bis(4-amino-3-methylcyclohexyl)methane, polyethyleneamines, polyoxyethyleneamines, and polyoxypropyleneamines, hydrazine, as well as any combination or mixture thereof.

[0076] In an even more advantageous embodiment, the at least one compound (v) is selected from the group consisting of meta-xylylenediamine, ethylenediamine, diethylenetriamine, any combination or mixture thereof.

[0077] In a particularly advantageous embodiment of the present disclosure, at least one compound (v) is selected to be meta-xylylenediamine. In the context of the present disclosure, it has actually been surprisingly found that ethylenically unsaturated polyurethane polymers (B) chain-extended with meta-xylylenediamine favorably influence the abrasion resistance as well as the non-yellowing properties of coatings obtained from the corresponding aqueous radiation-curable compositions.

[0078] When used in the synthesis of the ethylenically unsaturated polyurethane polymer (B), the amount of compound (v) is typically comprised in the range of 0 to 5 wt%, 0.1 to 5 wt%, 0.2 to 3 wt%, 0.5 to 3 wt%, 0.5 to 2 wt%, 1 to 2 wt%, or even 1 to 1.5 wt%, based on the total weight of the at least one ethylenically unsaturated polyurethane polymer (B).

[0079] The ethylenically unsaturated polyurethane polymer (B) may be obtained from the reaction of at least one further optional (polymerizable) ethylenically unsaturated polyurethane polymer (B), which is obtained from the reaction of at least one further compound (vi), which comprises at least two reactive groups capable of reacting with isocyanate groups and further comprises at least two ethylenically unsaturated groups, wherein compounds (A), (i), (ii), (iii), (iv), (v) and (vi) are all different from each other. The compound (vi) used herein is not particularly limited and will be easily identified by those skilled in the art in light of the present disclosure.

[0080] Typically, the optional compounds (vi) used herein contain at least two nucleophilic functional groups capable of reacting with isocyanate groups and further contain at least two ethylenically unsaturated groups. Advantageously, at least one compound (vi) contains a hydroxyl group and the ethylenically unsaturated group is a (meth)acrylic group.

[0081] More preferably, the at least one compound (vi) is selected from the reaction products of aliphatic and aromatic diglycidyl compounds with (meth)acrylic acid. Aliphatic diglycidyl compounds derived from α,ω diols having 4 to 12 carbon atoms or from polyoxyalkylene diols, particularly polyethylene glycols, polypropylene glycols, or mixtures thereof containing oxyalkylene groups, can be used. For example, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and hydrogenated bisphenol F diglycidyl ether, as well as their ethoxylated and / or propoxylated equivalents, are preferred. Diglycidyl esters such as diglycidyl hexahydrophthalate can also be used. Aromatic diglycidyl compounds derived from bisphenol A and bisphenol F are preferred.

[0082] In a particularly advantageous embodiment, the at least one compound (vi) is selected from the diacrylate esters of bisphenol A and bisphenol F diglycidyl ethers, and their ethoxylated and / or propoxylated equivalents, as well as any combination or mixture thereof. Diglycidyl esters such as diglycidyl phthalate, N,N-diglycidylaniline, and N,N-diglycidyl-4-glycidyloxyaniline can also be used. Diacrylate esters of bisphenol A diglycidyl ether are particularly preferred.

[0083] When used in the synthesis of the ethylenically unsaturated polyurethane polymer (B), the amount of compound (vi) is typically comprised in the range of 0 to 30 wt%, 0.5 to 30 wt%, 1 to 20 wt%, 2 to 15 wt%, or even 3 to 10 wt%, based on the total weight of the at least one ethylenically unsaturated polyurethane polymer (B).

[0084] According to advantageous embodiments, the aqueous radiation curable composition of the present disclosure comprises 25 to 55 wt. %, 30 to 55 wt. %, or even 30 to 50 wt. % of at least one ethylenically unsaturated polyurethane polymer (B), based on the total dry content of the radiation curable composition.

[0085] According to a particular embodiment, the at least one ethylenically unsaturated polyurethane polymer (B) used herein is i. 5 to 60 wt.%, 10 to 50 wt.%, 15 to 40 wt.%, or even 20 to 30 wt.% of at least one polyisocyanate compound (i), ii. 2 to 50 wt.%, 3 to 30 wt.%, 5 to 25 wt.%, or even 7 to 25 wt.% of at least one polymerizable polyol (ii); iii. 1 to 25 wt. %, 2 to 20 wt. %, 3 to 15 wt. %, or even 4 to 10 wt. % of at least one hydrophilic compound (iii) comprising at least one reactive group capable of reacting with an isocyanate group and at least one group capable of dispersing the polyurethane polymer (B) in an aqueous medium either directly or after reaction with a neutralizing agent to provide a salt, iv. 10 to 60%, 20 to 60%, 15 to 55%, 20 to 55%, or even 30 to 50% by weight of at least one compound (iv) containing at least one (essentially one) reactive group capable of reacting with an isocyanate group and further containing at least one ethylenically unsaturated group; v. optionally, 0-5 wt. %, 0.1-5 wt. %, 0.2-3 wt. %, 0.5-3 wt. %, 0.5-2 wt. %, 1-2 wt. %, or even 1-1.5 wt. % of at least one (non-polymerizable) compound (v) comprising at least one (essentially one) reactive group capable of reacting with an isocyanate group, and vi. optionally obtained from the reaction of 0-30%, 0.5-30%, 1-20%, 2-15%, or even 3-10% by weight of at least one compound (vi) comprising at least two reactive groups capable of reacting with isocyanate groups and further comprising at least two ethylenically unsaturated groups; Compounds (i), (ii), (iii), (iv), (v), and (vi) are all different from one another, and the weight percentages are based on the total weight of the at least one ethylenically unsaturated polyurethane polymer (B).

[0086] In a typical embodiment, the ethylenically unsaturated polyurethane polymer (B) is a (meth)acrylated polyurethane polymer (B), where the ethylenically unsaturated functional site is a (meth)acrylic group.

[0087] In another exemplary embodiment, the ethylenically unsaturated polyurethane polymer (B) contains less than 0.20 meq / g, less than 0.15 meq / g, less than 0.10 meq / g, less than 0.05 meq / g, or even less than 0.01 meq / g of allophanate groups.

[0088] According to an exemplary embodiment, the ethylenically unsaturated polyurethane polymer (B) has a weight average molecular weight (M) of greater than 3000 g / mol, greater than 5000 g / mol, greater than 8000 g / mol, greater than 10,000 g / mol, or even greater than 15,000 g / mol. w )

[0089] More typically, the ethylenically unsaturated polyurethane polymer (B) has a weight average molecular weight (M) in the range of 2500 to 25,000 g / mol, 3000 to 20,000 g / mol, 5000 to 20,000 g / mol, 8000 to 20,000 g / mol, 8000 to 15,000 g / mol, or even 10,000 to 15,000 g / mol. w )

[0090] According to a particular embodiment, in which the ethylenically unsaturated polyurethane polymer (B) is chain extended by reaction with at least one compound (iv) comprising at least one reactive group capable of reacting with an isocyanate group and further comprising at least one ethylenically unsaturated group, the resulting ethylenically unsaturated polyurethane polymer (B) has a weight average molecular weight (M) of more than 20,000 g / mol, more than 30,000 g / mol, more than 50,000 g / mol, more than 80,000 g / mol, more than 100,000 g / mol, more than 120,000 g / mol, more than 150,000 g / mol, more than 180,000 g / mol, or even more than 200,000 g / mol. w )

[0091] More specifically, the at least one ethylenically unsaturated (chain extended) polyurethane polymer (B) has a weight average molecular weight (M) in the range of 25,000 to 300,000 g / mol, 30,000 to 280,000 g / mol, 50,000 to 250,000 g / mol, 50,000 to 230,000 g / mol, 80,000 to 230,000 g / mol, 100,000 to 200,000 g / mol, or even 150,000 to 200,000 g / mol. w )

[0092] In one advantageous aspect, the aqueous radiation curable composition of the present disclosure has a particle (droplet) size of 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or even 100 nm or less, as determined by DLS measurements according to the test methods described in the Examples.

[0093] In another advantageous embodiment, the aqueous radiation curable composition has a particle (droplet) size in the range of 80 to 350 nm, 80 to 300 nm, 80 to 250 nm, 85 to 200 nm, 85 to 150 nm, or even 90 to 120 nm, as determined by DLS measurements according to the test methods described in the examples.

[0094] In other advantageous embodiments, the aqueous radiation curable composition has a solids content in the range of 20 to 50 wt. %, 30 to 50 wt. %, 30 to 40 wt. %, or even 35 to 40 wt. %, as determined gravimetrically according to the test methods described in the Examples.

[0095] According to another beneficial aspect, the aqueous radiation curable compositions described herein have a viscosity of 500 mPa s or less, 400 mPa s or less, 300 mPa s or less, 200 mPa s or less, 150 mPa s or less, 100 mPa s or less, or even 50 mPa s or less, as determined according to the test methods described in the Examples.

[0096] According to more advantageous embodiments, the aqueous radiation curable composition has a viscosity in the range of 10 to 500 mPa s, 20 to 400 mPa s, 50 to 300 mPa s, 50 to 250 mPa s, 50 to 200 mPa s, 50 to 150 mPa s, or even 50 to 100 mPa s, as determined according to the test methods described in the examples.

[0097] The aqueous radiation curable compositions of the present disclosure possess advantageous properties, particularly relatively small particle size and relatively low viscosity, which not only beneficially affect overall stability but also contribute to providing corresponding coatings and articles with the superior properties and performance attributes detailed above.

[0098] Advantageously, the aqueous radiation curable compositions described herein are at least partially bio-based, in particular having a biocarbon content of more than 5%, more than 10%, more than 15%, or even more than 20% by weight of the total carbon content of the composition, where the bio-based content is determined according to the ASTM D6866 standard test method.

[0099] As is conventional in the art, the aqueous radiation-curable compositions of the present disclosure may further comprise a variety of additional ingredients, depending on the targeted application and features of such compositions. In a typical embodiment, the aqueous radiation-curable composition further comprises at least one additive selected from the group consisting of photoinitiators, inhibitors, antioxidants, biocides, UV stabilizers, UV absorbers, nanoparticles, dispersants, slip aids, fillers, plasticizers, flow additives, antifoam additives, rheology modifiers, anti-settling agents, wetting agents, defoamers, flame retardants, leveling agents, slip agents, water scavengers, matting agents, waxes, pigments, dyes, cosolvents, resinous materials dispersed or solubilized in the composition, and any combination or mixture thereof.

[0100] In an advantageous embodiment, the aqueous radiation-curable composition may further comprise one or more external thermal crosslinkers that allow for dual curing (radiation and heat). Examples of suitable crosslinkers are (blocked) polyisocyanates, polyaziridines, polycarbodiimides, polyepoxides, polyalkoxysilanes, and metal salts such as ammonium zirconium carbonate. Polyisocyanates are particularly suitable, in particular hydrophilic polyisocyanates commercially available from Covestro AG under the trade name BAYHYDUR.

[0101] The aqueous radiation-curable composition of the present disclosure can be prepared in a variety of ways according to techniques well known to those skilled in the art. In a typical procedure, the composition is prepared by reacting compounds (i), (ii), and (iii), optionally compound (vi), and optionally other ingredients, in a suitable solvent at a temperature of 20 to 80°C with stirring until a suitable isocyanate content is reached. The resulting reaction product is then further reacted with compound (iv) to obtain an ethylenically unsaturated polyurethane polymer (B). The resulting polymer (B) may be chain-extended according to conventional procedures, particularly with optional compound (v).

[0102] The aqueous radiation-curable compositions disclosed herein typically contain 25 to 95 wt. % water, more typically 35 to 60 wt. % water, based on the total weight of the composition. Compositions according to the present disclosure typically contain 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. % organic solvents and volatile organic compounds (VOCs), 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.

[0103] According to another aspect, the present disclosure relates to a coating composition comprising the aqueous radiation-curable composition described above. The aqueous radiation-curable composition disclosed herein is in fact particularly well suited for preparing coatings. All the specific preferred aspects described above in the context of the aqueous radiation-curable composition, particularly with regard to the ethylenically unsaturated compound (A) and the ethylenically unsaturated polyurethane polymer (B), are fully applicable to the coating composition.

[0104] Advantageously, coatings obtained from the described waterborne radiation curable compositions possess excellent properties and performance attributes with respect to adhesion to difficult-to-bond plastic substrates (specifically polycarbonate and acrylonitrile butadiene styrene), hot water resistance, hydrolysis resistance, visual aesthetics in complex formulations (such as metallic or matte formulations), abrasion resistance, stain resistance, and low VOC characteristics.

[0105] In an advantageous embodiment, the coating composition is a hard coat composition.Therefore, the aqueous radiation curable composition of the present disclosure is very suitable for forming coatings used in 3C applications, which are of particular interest in the context of the present disclosure.The product applications in this industry segment are practically limitless, and can typically be related to consumer electronics (such as mobile phones, computers, televisions, compact discs, etc.), automotive plastics for interior applications (such as dashboards, trims, etc.) or exterior applications (such as headlights, mirrors, bumpers, wheel covers, etc.), and industrial plastics (such as films, labels, boxes, toys, sports equipment, garden furniture, etc.).

[0106] 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.

[0107] Therefore, according to another aspect, the present disclosure relates to an ink (e.g., inkjet), overprint varnish, adhesive, or three-dimensional article comprising the above-described water-based radiation curable composition or coating composition.

[0108] Yet another aspect of the present disclosure relates to an article or substrate that is at least partially coated, printed, or treated with the waterborne radiation curable composition, coating composition, ink, overprint, varnish, or adhesive described above.

[0109] In yet another aspect of the present disclosure, there is provided a method for producing an aqueous radiation curable composition, comprising: a) mixing and reacting compounds (i), (ii), (iii), and optionally compound (vi) as described above; b) reacting the product of step a) with compound (iv) described above, thereby obtaining an ethylenically unsaturated polyurethane polymer (B); c) adding at least one ethylenically unsaturated compound (A) as described above; d) optionally reacting compound (iii) with a neutralizing agent to convert the hydrophilic group provided by compound (iii) into an anionic salt; e) dispersing the ethylenically unsaturated polyurethane polymer (B) obtained in step b) or optional step d) in an aqueous medium; f) optionally reacting the ethylenically unsaturated polyurethane polymer (B) obtained in step e) with compound (v) as described above.

[0110] When compound (v) is used as a chain extender, it is typically added after the optional neutralization step of the hydrophilic groups provided by compound (iii) and after dispersion of the ethylenically unsaturated polyurethane polymer (B). Chain extension of the ethylenically unsaturated polyurethane polymer (B) is carried out according to conventional procedures well known to those skilled in the art.

[0111] According to yet another aspect, the present disclosure provides a method for coating an object or substrate, comprising: a) providing an aqueous radiation curable composition or coating composition as described above; b) applying the composition to at least a portion of a surface of an object or substrate; and c) curing the composition by subjecting the coated surface to actinic radiation and / or thermal energy.

[0112] Typically, a water evaporation step is carried out before the curing step. Typically, at least 98%, preferably at least 99%, and preferably all of the water is evaporated. The active energy rays used for curing are preferably ultraviolet light, electron beam, X-ray, radioactive, or high-frequency light. Ultraviolet light with a wavelength of 180 to 400 nm is particularly preferred from an economical standpoint. Curing by irradiation may be followed by, or alternatively replaced by, thermal curing in the presence of a suitable external (thermal) crosslinker.

[0113] In certain aspects of the present invention, the article or substrate comprises plastic, and more particularly is made from plastic.

[0114] The aqueous radiation-curable compositions or coating compositions described above are typically cured by ultraviolet radiation, generally in the presence of a photoinitiator. Alternatively, they can be cured by electron beam radiation, allowing the use of photoinitiator-free compositions. The compositions according to the present invention offer extremely rapid curing, characterized by higher reactivity, which allows for higher line speeds or less radiation energy curing, and improved productivity. Low-energy ultraviolet light sources (LED lamps) can also be used.

[0115] According to yet another aspect, the present disclosure relates to the use of the above-described waterborne radiation curable or coating compositions in computer, communications, and consumer electronics applications, dual cure applications, or thick pigmentation systems. [Example]

[0116] The present disclosure is further illustrated by the following examples, which are for illustrative purposes only and are not intended to limit the scope of the appended claims.

[0117] Throughout this disclosure and the examples, the following test and measurement methods are used to characterize exemplary aqueous radiation curable compositions and coatings obtained therefrom.

[0118] Test Method: A) Particle size Dynamic light scattering (DLS) measurements are used to characterize the hydrodynamic size of particles in various aqueous compositions. Prior to DLS measurements, concentrated compositions are diluted with deionized distilled water to obtain a particle concentration of 0.05 w / w%. The diluted compositions are then filtered. DLS measurements are then performed at 23°C using a Beckman-Coulter Delsa Nano-c particle analyzer. The wavelength of incident monochromatic light used in DLS measurements is λ = 658 nm. Scattered light is detected at an angle of 165° in a near-backscattering configuration. The z-average particle size, along with the polydispersity index, is determined from second-order cumulant analysis of the electric field autocorrelation function. The single-particle diffusion coefficient is then estimated from the average decay constant. From there, the median particle size d is calculated using the Stokes' relationship. 50 can be derived.

[0119] B) Solid content The solids content (SC) of the various aqueous compositions is determined by a gravimetric method including a drying step at 120° C. for 2 hours.

[0120] C) Viscosity The viscosity of the various aqueous compositions is measured at 23° C. using a cone-plate rheometer MCR092 (Paar-Physica) according to test method DIN EN ISO 3219. A fixed shear rate of 25 s −1 is used.

[0121] D) Colloidal stability Colloidal stability of various aqueous compositions is assessed at 23°C by visually observing decantation and / or phase separation (expressed as a percentage of the total height) in samples weighing 20 g and placed in an oven at 60°C. Colloidal stability is reported herein as the number of days until settling exceeds 2% of the total height of the sample. In the context of this disclosure, good colloidal stability is achieved if no degradation of the product is observed for at least 10 days at 60°C.

[0122] E) Molecular weight and polydispersity The number-average molecular weight (Mn), weight-average molecular weight (Mw), and polydispersity (D) were determined by conventional gel permeation chromatography (GPC) using Polymer Laboratories EasyCal polystyrene standards (molecular weight range: 200-400,000 g / mol). Samples were dissolved in tetrahydrofuran (THF) containing 0.5% toluene as a flow marker (1.0% wt. / wt.). Analysis was performed by liquid chromatography (Merck-Hitachi L7100) equipped with three PLGel Mixed-D LS polystyrene-divinylbenzene GPC columns (300 x 7.5 mm x 5 μm). Sample components were separated by the GPC columns based on molecular size in solution and detected by a refractive index detector. Data were collected and processed using Polymer Laboratories Cirrus GPC software.

[0123] F) Glossiness Gloss evaluation is carried out on coatings formed on Leneta Plain White Chart. Gloss values ​​are given in gloss units at an angle of 60° [GU] and are determined in accordance with test method DIN EN ISO 2813.

[0124] G) Adhesiveness The adhesive performance of the coatings to the surface of the corresponding substrate (initial adhesion ADH) is evaluated using a crosshatch test according to test method ASTM D3359 B. In each case, five parallel cuts, 1 cm long and 1 mm apart, are first made in the coating using a knife. Next, five parallel cuts, 1 cm long and 1 mm apart, are made transversely. An adhesive tape (Scotch®) is then firmly pressed onto the cross-cut coating and quickly removed. Damage to the cross-cut surface area of ​​the coating due to loss of adhesion is expressed on a scale of 0B to 5B, with a score of 5 corresponding to the best adhesion.

[0125] H) Hot water resistance This resistance test is performed only on coatings that show good initial adhesion (ADH test = 5B). The coating is immersed in hot water (temperature 80 or 85°C) for 30 or 60 minutes. The adhesive performance of the crosshatch tape is re-evaluated on the coating, which has been dried according to the procedure described above. The hot water resistance test is passed if it achieves a score of at least 4B.

[0126] I) Hydrolysis resistance This resistance test is performed according to industry test standard VW TL 226 (Volkswagen AG) on only those coatings that exhibit excellent initial adhesion (ADH test = 5B). The coated substrates are placed in a humidity chamber at 60°C and 95% relative humidity for 96 hours. The coatings on the coated substrates are then evaluated for visual damage, gloss, and crosshatch adhesion after the humidity test. The hydrolysis resistance test is considered to have passed if the coating is not visually damaged and achieves the same level of gloss and adhesion before and after the test.

[0127] J) Scratch resistance Scratch resistance is determined using a Resistant Coating to Abrasion (RCA) abrader - Norman Tool Tester, according to test method ASTM F-2357. The RCA test is performed using standard paper as the abrasive. Abrasion is performed by pressing the standard paper onto the coated polycarbonate substrate with a specific load (175 g). The back side of the standard paper is in contact with a rubber ring. The results are expressed as the number of cycles required until the coated substrate begins to show visual damage, cloudiness, or white areas. The higher the number of cycles, the better the abrasion resistance.

[0128] K) Stain resistance The stain resistance of the coatings is evaluated after applying a 50-micrometer wet layer to a nonporous substrate (white opacity chart, Leneta) sheet with a Mayer bar, followed by drying at 50°C for 6 minutes and UV curing with an 80 W / cm Hg lamp at a conveyor speed of 5 m / min. The stain resistance is evaluated 24 hours after the coating has cured by applying a glass microfiber filter strip saturated with the test substance onto the coating or by contacting the coating with a black alcohol marker with reference number Artline N70 for 16 hours. The test substances used are mustard, coffee, eosin, isobetadine, methyl blue, and ammonia (10% solution in water). The stain is then cleaned by rubbing several times with a tissue saturated with water or isopropanol. The remaining stain is visually evaluated using a scale of 1 to 5, with 5 = no stain remaining. The average stain resistance scores are shown below. A high stain resistance (at least a score of 4) is expected to provide the best coating protection against spills of any household product.

[0129] Raw materials: In this example, the following raw materials and starting products are used: H12MDI is 4,4'-methylenedicyclohexyl diisocyanate commercially available from Covestro. IPDI is isophorone diisocyanate available from Evonik. Desmophen® C 2102 is a polycarbonate diol with a molecular weight of 1000 g / mol, commercially available from Covestro, hereafter referred to as PC-1000. DMPA is dimethylolpropionic acid, commercially available from Geo Specialty Chemicals, Inc. DPHA is a mixture of dipentaerythritol penta- and hexaacrylates with an IOH range of 45-75, commercially available from Allnex Germany GmbH. PETIA is pentaerythritol triacrylate commercially available from Allnex Germany GmbH. IRR 1094 is a hexafunctional aliphatic urethane acrylate oligomer available from Allnex Germany GmbH. Ebecryl® 140 is ditrimethylolpropane tetraacrylate commercially available from Allnex Germany GmbH, hereafter referred to as E-140. TMPTA is trimethylolpropane triacrylate available from Allnex Germany GmbH. HDDA is 1,6-hexanediol diacrylate commercially available from Allnex Germany GmbH. EOEOEA is ethoxyethoxyethyl acrylate commercially available from Rahn USA Corp. under the trade name Miramer M170. MXDA is meta-xylylenediamine commercially available from Huntsman. Ebecryl® 600 is an acrylic acid adduct of bisphenol A diglycidyl ether, available from Allnex GmbH, hereafter referred to as E-600. Additol® HDMAP (also known as Photoinitiator 1173) is a photoinitiator commercially available from Allnex GmbH, Germany, hereafter referred to as A-HDMAP. BYK® 349 is a polyether-modified siloxane defoamer commercially available from BYK. Valikat Bi 2010 is a bismuth carboxylate-based PU catalyst commercially available from Umicore, hereafter referred to as VB-2010. BHT is butylated hydroxytoluene commercially available from Brenntag. TEA is triethylamine commercially available from BASF. Tafigel® PUR40 is a non-ionic polyurethane butyl triglycol / water associative thickener commercially available from Munzing, hereafter referred to as T-PUR40. Tafigel® PUR65 is a non-ionic polyurethane butyl triglycol / water associative thickener commercially available from Munzing, hereafter referred to as T-PUR80. Additol® XL250 is an anionic wetting and dispersing phosphine available from Allnex Germany GmbH, hereafter referred to as A-XL250. Omnirad 500 is a photoinitiator commercially available from IGM Resins, hereafter referred to as OMN-500. Additol® TPO is a phosphine oxide photoinitiator commercially available from Allnex GmbH, Germany, hereafter referred to as A-TPO. NIPSIL E1011 is a matting agent commercially available from Tosoh Corporation of Japan, hereinafter referred to as N-E1011. 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.

[0130] example: Example 1: Basic Preparation of Exemplary Aqueous Radiation Curable Compositions (Examples 1-8) and Comparative Example (Example C1) A double-walled glass reactor equipped with a mechanical stirrer, thermocouple, steam condenser, and dropping funnel is charged with polymerizable polyol (ii), optionally compound (vi), hydrophilic compound (iii), polyisocyanate compound (i), acetone, and catalyst (VB-2010 or DBTL). The reaction mixture is heated to 60°C with stirring and maintained under reflux until the appropriate isocyanate content is reached. Compound (iv) is then added to the reactor, and the reaction mixture is maintained under reflux until the appropriate isocyanate content is reached. The ethylenically unsaturated compound (A) is then added to the reaction mixture and stirred until a homogeneous mixture is obtained. The mixture is further cooled to 45°C, and triethylamine is added with stirring. The resulting mixture is then slowly added to room temperature water under high shear stirring until a stable aqueous composition is obtained. In the aqueous radiation-curable compositions according to Examples 1 to 7 and Comparative Example C1, which include a chain extension step, compound (v) is added immediately after this stabilization step. Acetone is stripped off under vacuum at a temperature of 50° C. until the level is less than 0.15% by weight by gas chromatography. [Table 1]

[0131] Example 2: Properties and Stability Performance of Exemplary Waterborne Radiation Curable Compositions (Examples 1-8) The properties and stability performance of exemplary aqueous radiation-curable compositions (Examples 1-8) were determined according to the test methods described above. The exemplary compositions of Examples 1-7 all contain a chain-extended ethylenically unsaturated polyurethane polymer (B), while the exemplary composition of Example 8 contains a non-chain-extended ethylenically unsaturated polyurethane polymer (B). The results are shown in Table 2 below. [Table 2]

[0132] As can be seen from the results shown in Table 2, the aqueous radiation-curable compositions according to the present disclosure (Examples 1-8) exhibit excellent colloidal stability even under severe aging conditions, as well as advantageous properties, such as relatively small particle size and relatively high solids content.

[0133] Example 3: Basic Preparation of Exemplary Clear Coating Compositions (Examples 9-16) and Comparative Clear Coating Composition (Example C2) Exemplary clear coating compositions according to Examples 9 to 16, and a comparative clear coating according to Example C2, are further prepared based on the formulations set forth in Table 3 below. The comparative clear coating according to Example C2 is prepared based on the comparative formulation of Example C1, which contains 14.5 wt. % of Compound (A) based on the dry weight content of the composition of Example C1. [Table 3]

[0134] The clear coating formulation is applied to a polycarbonate substrate using a bar coater, thereby obtaining a 50 micrometer wet coating layer. The applied formulation is dried at 50°C for 6 minutes and then heated to 80 watts / cm. 2 The coating is cured under UV light using a 1000 kJ Hg lamp at a curing speed of 5 m / min. The cured coating is then used for further testing.

[0135] Example 4: Basic Preparation of Exemplary Metal Coating Compositions (Examples 17-19) Exemplary metal coating compositions according to Examples 17-19 are further prepared based on the formulations set forth in Table 4 below. [Table 4]

[0136] The metal coating formulation is applied to a plastic substrate (PC or ABS) using a spray coater. The applied formulation is dried at 60°C for 10 minutes, thereby obtaining a dry film thickness (DFT) of approximately 10 micrometers. The coating is then cured under UV light using an 80 watt / cm2 Hg lamp at a curing speed of 5 m / min. The cured coating is then used for further testing.

[0137] Example 5: Stain Resistance Performance of Exemplary Clear Coatings (Examples 9-13) The stain resistance performance of the exemplary clear coatings (Examples 9-13) was determined according to the test methods described above, and the results are shown in Table 5 below. [Table 5]

[0138] As can be seen from the results shown in Table 5, the clear coatings according to the present disclosure (Examples 19 to 13) have excellent stain resistance against various types of stains.

[0139] Example 6: Adhesion and Hot Water Resistance of Exemplary Clear Coatings (Examples 11-16) and Comparative Clear Coating (Example C2) The adhesion to polycarbonate substrates, as well as the hot water resistance performance, of the exemplary clear coatings (Examples 11-16) and the comparative clear coating (Example C2) were determined according to the test methods described above, and the results are shown in Table 6 below. [Table 6]

[0140] As can be seen from the results shown in Table 6, clear coatings according to the present disclosure (Examples 11-16) exhibit excellent performance attributes with respect to adhesion to polycarbonate substrates and hot water resistance, even under stringent conditions. In contrast, the performance and properties obtained with a comparative clear coating not according to the present disclosure (Example C2) are less favorable. In particular, the comparative clear coating typically exhibits poor hot water resistance.

[0141] Example 7: Hydrolysis Resistance Performance of Exemplary Clear Coatings (Examples 14 and 16) and Comparative Clear Coating (Example C2) The adhesion of the exemplary clear coatings (Examples 14 and 16) and the comparative clear coating (Example C2) to polycarbonate substrates, as well as the hot water resistance performance, were determined according to the test methods described above. The results are shown in Table 7 below. [Table 7]

[0142] As can be seen from the results shown in Table 7, the clear coatings according to the present disclosure (Examples 11 and 16) have excellent hydrolysis resistance even under harsh conditions. In contrast, the comparative clear coating (Example C2) not according to the present disclosure exhibits poor hydrolysis resistance.

[0143] Example 8: Performance Attributes of Exemplary Metal Coatings (Examples 17-19) Various performance attributes of the exemplary metal coatings (Examples 17-19), specifically adhesion to polycarbonate substrates, scratch resistance, and gloss, were determined according to the test methods described above, and the results are shown in Table 8 below. [Table 8]

[0144] As can be seen from the results shown in Table 8, the metal coatings according to the present disclosure (Examples 17-19) have excellent performance attributes with respect to adhesion to polycarbonate substrates, scratch resistance, and gloss.

Claims

1. 1. An aqueous radiation-curable composition comprising (A) and (B): a) 45 to 80% by weight of at least one ethylenically unsaturated compound (A); b) 20 to 55% by weight of at least one ethylenically unsaturated polyurethane polymer (B), i. at least one polyisocyanate compound (i); ii. at least one polymerizable polyol (ii); iii. At least one hydrophilic compound (iii) containing at least one reactive group capable of reacting with an isocyanate group and at least one group capable of dispersing the polyurethane polymer (B) in an aqueous medium, either directly or after reaction with a neutralizing agent, to provide a salt; iv. at least one compound (iv) containing at least one reactive group capable of reacting with an isocyanate group and further containing at least one ethylenically unsaturated group; and v. optionally, at least one compound (v) containing at least one reactive group capable of reacting with an isocyanate group; an ethylenically unsaturated polyurethane polymer (B) obtained by the reaction of compounds (A), (i), (ii), (iii), (iv), and (v) are all different from one another, and the weight percentages are based on the total dry weight content of the radiation curable composition; Aqueous radiation curable composition.

2. 10. The aqueous radiation curable composition of claim 1, comprising more than 45 wt.%, more than 50 wt.%, more than 55 wt.%, more than 60 wt.%, more than 65 wt.%, more than 70 wt.%, or even more than 75 wt.% of the at least one ethylenically unsaturated compound (A), said wt.% being based on the total dry content of the radiation curable composition.

3. 3. The aqueous radiation curable composition according to claim 1, wherein the at least one ethylenically unsaturated compound (A) is selected from the group consisting of monomers, oligomers, polymers, in particular oligomers, and any combination or mixture thereof.

4. 4. The aqueous radiation curable composition of claim 1, wherein the at least one ethylenically unsaturated compound (A) is selected from the group consisting of urethane (meth)acrylates (A1), polyester (meth)acrylates (A2), epoxy (meth)acrylates (A3), (meth)acrylic (meth)acrylates (A4), and any combination or mixture thereof.

5. The at least one polymerizable polyol (ii) has a weight average molecular weight (M ｗ 5. The aqueous radiation curable composition of claim 1, wherein

6. 6. The aqueous radiation curable composition of any one of claims 1 to 5, wherein the at least one polymerizable polyol (ii) is selected from the group consisting of polycarbonate polyols, polyester polyols, polyether polyols, fatty dimer diols, polybutadiene polyols, polyacrylate polyols, silicone polyols, and any combination or mixture thereof.

7. 7. The aqueous radiation curable composition according to any one of claims 1 to 6, wherein the at least one hydrophilic compound (iii) is a non-polymerizable compound selected in particular from the group of polyols comprising one or more anionic bases.

8. 8. The aqueous radiation curable composition according to any one of claims 1 to 7, wherein the at least one compound (iv) comprises essentially one reactive group capable of reacting with an isocyanate group and further comprises at least one, in particular at least two, ethylenically unsaturated groups.

9. 9. The aqueous radiation curable composition according to any one of claims 1 to 8, wherein the at least one compound (v) is selected from the group of aliphatic, cycloaliphatic, aromatic, or heterocyclic primary or secondary polyamines or hydrazines having up to 60, in particular up to 12, carbon atoms.

10. 10. The aqueous radiation curable composition of any one of claims 1 to 9, wherein the at least one ethylenically unsaturated polyurethane polymer (B) is obtained from the reaction of at least one further compound (vi) comprising at least two reactive groups capable of reacting with isocyanate groups and further comprising at least two ethylenically unsaturated groups, and wherein compounds (A), (i), (ii), (iii), (iv), (v), and (vi) are all different from one another.

11. 11. The aqueous radiation curable composition of any one of claims 1 to 10, comprising 25 to 55 wt.-%, 30 to 55 wt.-%, or even 30 to 50 wt.-%, of the at least one ethylenically unsaturated polyurethane polymer (B), based on the total dry weight content of the radiation curable composition.

12. 12. The aqueous radiation curable composition of any one of claims 1 to 11, having a particle size of 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or even 100 nm or less, as determined by DLS measurement according to the test method described in the examples.

13. A coating composition comprising the aqueous radiation curable composition of any one of claims 1 to 12.

14. 1. A method for producing an aqueous radiation curable composition, comprising: a) mixing and reacting compounds (i), (ii), (iii) and optionally compound (vi) according to any one of claims 1 to 10; b) reacting the product of step a) with a compound (iv) according to any one of claims 1 to 10, thereby obtaining an (end-capped) ethylenically unsaturated polyurethane polymer (B); c) adding at least one ethylenically unsaturated compound (A) according to any one of claims 1 to 10; d) optionally reacting said compound (iii) with a neutralizing agent to convert the hydrophilic group provided by compound (iii) into an anionic salt; e) dispersing the ethylenically unsaturated polyurethane polymer (B) obtained in step b) or optional step d) in an aqueous medium; f) optionally reacting the ethylenically unsaturated polyurethane polymer (B) obtained in step e) with a compound (v) according to any one of claims 1 to 10; A method comprising:

15. Use of the aqueous radiation curable or coating composition according to any one of claims 1 to 13 in computer, communication and consumer electronics applications, dual cure applications or thick pigmented systems.

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