COMPOSITIONS, COMPRISING SILVER NANOPLATELETS

Abstract

The present invention relates to radically curable compositions, comprising (A) silver nanoplatelets, (B) one reactive diluent comprising 1 to 4 (meth)acrylate groups; (C) one, or more urethane (meth)acrylates (C), which are obtainable by reaction of the following components: (a) at least one isocyanate having two isocyanate groups, (b) at least one polyalkylene oxide polyether having at least 2 hydroxyl groups, (c) at least one hydroxy-functional (meth)acrylate having one hydroxyl group and one (meth)acrylate group, (d) at least one compound having at least one isocyanate reactive group and at least one acid function, (e) if component (d) is present, optionally at least one basic compound which is present for neutralization or partial neutralization of the acid groups of component (d), (f) optionally at least one monoalcohol having one hydroxy function, and (g) optionally at least one compound having at least one primary and/or secondary amino group; (D) one, or more photonitiators; printing inks containing the compositions and their use for the production security products. Coatings obtained after curing of the compositions, show one color, when observed in transmission and another color, when observed in reflection on both sides of the cured coating. The metal-like reflection of the coatings may be further enhanced by the presence of surfactants.

Claims

1.-15. (canceled)

16. A radically curable composition, comprising (A) silver nanoplatelets, (B) one reactive diluent comprising 1 to 4 (meth)acrylate groups; (C) one, or more urethane (meth)acrylates (C), which are obtainable by reaction of the following components: (a) at least one isocyanate having two isocyanate groups, (b) at least one polyalkylene oxide polyether having at least 2 hydroxyl groups, (c) at least one hydroxy-functional (meth)acrylate having one hydroxyl group and one (meth)acrylate group, (d) at least one compound having at least one isocyanate reactive group and at least one acid function, (e) if component (d) is present, optionally at least one basic compound which is present for neutralization or partial neutralization of the acid groups of component (d), (f) optionally at least one monoalcohol having one hydroxy function; and (g) optionally at least one compound having at least one primary and/or secondary amino group, (D) one, or more photonitiators; (E) optionally one, or more reactive diluents, which are different from component (B); (F) optionally one, or more oligomers, which are different from component (C); (G) optionally one, or more surfactants; (H) optionally one, or more polymeric binders; and (I) optionally further additives.

17. The composition according to claim 16, wherein the urethane (meth)acrylate (C) is obtainable by reaction of the following components: (a) at least one isocyanate having two isocyanate groups, (b) at least one polyalkylene oxide polyether having at least 2 hydroxyl groups, (c) at least one hydroxy-functional (meth)acrylate having one hydroxyl group and one (meth)acrylate group, (d) at least one compound having at least one isocyanate reactive group and at least one acid function, (e) if component (d) is present, optionally at least one basic compound which is present for neutralization or partial neutralization of the acid groups of component (d), (f) optionally at least one monoalcohol having one hydroxy function, and (g) optionally at least one compound having at least one primary and/or secondary amino group.

18. The composition according to claim 16, wherein component (B) is selected from octyl acrylate; decyl acrylate; lauryl acrylate, tridecyl acrylate; isodecyl acrylate; stearyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, octyl methacrylate, lauryl methacrylate, isodecyl methacrylate, tridecyl methacrylate; tetradecyl methacrylate; isodecyl methacrylate and stearyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate; isobornyl acrylate; 4-tert-butylcyclohexyl acrylate; cyclohexylmethacrylate, isobornyl methacrylate, tetrahydrofurfuryl acrylate, (5-ethyl-1,3-dioxan-5-yl)methyl acrylate, ethoxylated phenyl acrylate, ethoxylated phenyl methacrylate, nonyl phenol acrylate, nonyl phenol methacrylate, methoxy polyethyleneglycol acrylates, methoxy polyethyleneglycol methacrylates, methoxy polypropyleneglycol acrylates, methoxy polypropyleneglycol methacrylates, tetrahydrofurfuryl methacrylate, cyclic trimethylolpropane formal methacrylate, benzyl acrylate, 2-phenoxyethyl acrylate, ethoxylated (EO4) phenol acrylate; mixtures of ethoxylated (EO4) phenol acrylate and ethoxylated (EO8) nonylphenol acrylate; propoxylated (PO2) nonylphenol acrylate, ethoxylated o-phenylphenol acrylate, p-cumylphenoxylethyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, 2-(N-butylcarbamoyloxy)ethyl acrylate; and difunctional (meth)acrylates of formula ##STR00069## wherein R.sup.11 is independently in each occurrence H, or a C.sub.1-C.sub.4alkyl group. X.sup.1 is a group of formula ##STR00070## wherein m1 is 0, or 1; m2 is 0, or 1; m3 is 0, or an integer of 1 to 10; m4 is 0, or an integer of 1 to 10; m5 is 0, or an integer 1 to 8; R.sup.42 is independently in each occurrence H, or a C.sub.1-C.sub.4alkyl group; R.sup.40, R.sup.41, R.sup.43, R.sup.44, R.sup.45 and R.sup.46 are independently of each other H, or a C.sub.1-C.sub.4alkyl group; trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), ethoxylated trimethylolpropane triacrylates (in particular selected form the group consisting of ethoxylated (EO3) trimethylolpropane triacrylates, ethoxylated (EO6) trimethylolpropane triacrylates, ethoxylated (EO9) trimethylolpropane triacrylates), propoxylated trimethylolpropane triacrylates (PO3 TMPTA), ethoxylated glycerol triacrylates and propoxylated glycerol triacrylates (GPTA), pentaerythritol triacrylates (PETA, CAS no. 3524-68-3), ethoxylated pentaerythritol triacrylates, propoxylated pentaerythritol triacrylates (ethoxylated (EO3) pentaerythritol triacrylates, ethoxylated (EO6) pentaerythritol triacrylates and ethoxylated (EO9) pentaerythritol triacrylates); and tetrafunctional (meth)acrylates which are selected from bistrimethylolpropane tetraacrylate (DiTMPTA), pentaerythritol tetracrylate (PETTA), tetramethylolmethane tetramethacrylate, pentaerythritol tetramethacrylate, bistrimethylolpropane tetramethacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, ethoxylated dipentaerythritol tetraacrylate and propoxylated dipentaerythritol tetraacrylate.

19. The composition according to claim 16, wherein component B) is selected from dipropylene glycol diacrylate, tripropylene glycol diacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, octanediol diacrylate, octanediol dimethacrylate, nonanediol diacrylate, nonanediol dimethacrylate, decanediol diacrylate, decanediol dimethacrylate, cyclohexanediol diacrylate, cyclohexanediol dimethacrylate and cyclohexanedimethanol diacrylate.

20. The composition according to claim 16, wherein the photonitiator (D) is a compound of the formula ##STR00071## wherein R.sub.50 is unsubstituted cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl; or is cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl substituted by one or more halogen, C.sub.1-C.sub.12alkyl, C.sub.1-C.sub.12alkoxy, C.sub.1-C.sub.12alkylthio or by NR.sub.53R.sub.54; or R.sub.50 is unsubstituted C.sub.1-C.sub.20alkyl or is C.sub.1-C.sub.20alkyl which is substituted by one or more halogen, C.sub.1-C.sub.12alkoxy, C.sub.1-C.sub.12alkylthio, NR.sub.53R.sub.54 or by (CO)OC.sub.1-C.sub.24alkyl; R.sup.51 is unsubstituted cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl; or is cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl substituted by one or more halogen, C.sub.1-C.sub.12alkyl, C.sub.1-C.sub.12alkoxy, C.sub.1-C.sub.12alkylthio or by NR.sub.53R.sub.54; or R.sup.51 is (CO)R.sub.52; or R.sup.51 is C.sub.1-C.sub.12alkyl which is unsubstituted or substituted by one or more halogen, C1-C.sub.12alkoxy, C.sub.1-C.sub.12alkylthio, or by NR.sub.53R.sub.54; R.sup.52 and R.sub.52 independently of each other are unsubstituted cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl, or are cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl substituted by one or more halogen, C.sub.1-C.sub.4alkyl or C.sub.1-C.sub.4alkoxy; or R.sup.52 is a 5- or 6-membered heterocyclic ring comprising an S atom or N atom; R.sub.53 and R.sub.54 independently of one another are hydrogen, unsubstituted C.sub.1-C.sub.12alkyl or C.sub.1-C.sub.12alkyl substituted by one or more OH or SH wherein the alkyl chain optionally is interrupted by one to four oxygen atoms; or R.sub.53 and R.sub.54 independently of one another are C.sub.2-C.sub.12-alkenyl, cyclopentyl, cyclohexyl, benzyl or phenyl, or the photoinitiator (C) is a compound of the formula ##STR00072## wherein R.sub.29 is hydrogen or C.sub.1-C.sub.18alkoxy; R.sub.30 is hydrogen, C.sub.1-C.sub.18alkyl, C.sub.1-C.sub.12hydroxyalkyl, C.sub.1-C.sub.18alkoxy, OCH.sub.2CH.sub.2OR.sub.34, morpholino, SC.sub.1-C.sub.18alkyl, a group HC?CH.sub.2, C(CH.sub.3)?CH.sub.2, ##STR00073## D, E and f are 1-3; c is 2-10; G.sub.1 and G.sub.2 independently of one another are end groups of the polymeric structure; R.sub.34 is hydrogen, ##STR00074## R.sub.31 is hydroxy, C.sub.1-C.sub.16alkoxy, morpholino, dimethylamino or O(CH.sub.2CH.sub.2O).sub.gC.sub.1-C.sub.16alkyl; g is 1-20; R.sub.32 and R.sub.33 independently of one another are hydrogen, C.sub.1-C.sub.6alkyl, C.sub.1-C.sub.16alkoxy or O(CH.sub.2CH.sub.2O).sub.gC.sub.1-C.sub.16alkyl; or are unsubstituted phenyl or benzyl; or phenyl or benzyl substituted by C.sub.1-C.sub.12-alkyl; or R.sup.32 and R.sup.33 together with the carbon atom to which they are attached form a cyclohexyl ring; R.sub.35 is hydrogen, OR.sub.36 or NR.sub.37R.sub.38; R.sub.36 is hydrogen, C.sub.1-C.sub.12alkyl which optionally is interrupted by one or more non-consecutive O-atoms and which uninterrupted or interrupted C.sub.1-C.sub.12alkyl optionally is substituted by one or more OH, or R.sub.36 is ##STR00075## R.sub.37 and R.sub.38 independently of each other are hydrogen or C.sub.1-C.sub.12alkyl which is unsubstituted or is substituted by one or more OH; R.sub.39 is C.sub.1-C.sub.12alkylene which optionally is interrupted by one or more non-consecutive O, (CO)NHC.sub.1-C.sub.12alkylene-NH(CO) or ##STR00076## with the proviso that R.sub.31, R.sub.32 and R.sub.33 not all together are C.sub.1-C.sub.16alkoxy or O(CH.sub.2CH.sub.2O).sub.gC.sub.1-C.sub.16alkyl, or the photoinitiator is a mixture of different compounds of the formula (XII), or the photoinitiator is a mixture of compounds of the formula (XII) and (XI).

21. The composition according to claim 16, wherein the diluent (E) is selected from monofunctional (metha)acrylates, monofunctional vinylamides, monofunctional (meth)acrylamides, monofunctional vinyl esters, di(meth)acrylamides, divinyl esters, divinyl amides, trimethylolpropane formal (meth)acrylates, N-vinyloxazolidinones, N-Vinyl-caprolactam (NVC) and N-Vinyl-pyrrolidone (NVP), with the proviso that diluent (E) is different from component (B).

22. The composition according to claim 16, wherein the oligomer (F) is selected from (meth)acrylic oligomers, urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, polyether based (meth)acrylate oligomers, amine modified polyether based (meth)acrylate oligomers or epoxy (meth)acrylate oligomers, with the proviso that oligomer (F) is different from component (C).

23. The composition according to claim 16, wherein the surfactant (G) is selected from a polymer of formula
A-OR.sub.f(CF.sub.2).sub.xCFZCH.sub.2OR.sub.aC(?O)C(R.sub.bR.sub.c)X(1), wherein R.sub.f is a (per)fluoropolyoxyalkylene chain having an average number molecular weight M.sub.n ranging from 100 to 8,000, and comprising, repeating units, which may be equal to or different from one another, selected from: (i) CFYO, wherein Y is F or CF.sub.3, (ii) CFYCFYO, wherein Y, equal or different at each occurrence, is as above defined, with the proviso that at least one of Y is F, (iii) CF.sub.2CF.sub.2CW.sub.2O, wherein each of W, equal or different from each other, are F or H, (iv) CF.sub.2CF.sub.2CF.sub.2CF.sub.2O, (v) (CF.sub.2).sub.jCFZO wherein j is an integer from 0 to 3 and Z is a group of general formula ORFT, wherein Rf is a fluoropolyoxyalkene chain comprising a number of repeating units from 0 to 10, said recurring units being chosen among the followings: CFYO, CF.sub.2CFYO, CF.sub.2CF.sub.2CF.sub.2O, CF.sub.2CF.sub.2CF.sub.2CF.sub.2O, with each of each of Y being independently F or CF.sub.3 and T being a C.sub.1-C.sub.3 perfluoroalkyl group; Z is fluorine or CF.sub.3; x is 0 or 1, with the proviso that, when, x is 1, Z is F; R.sub.a is a polyoxyalkylene chain free from fluorine atoms, said chain comprising from 4 to 50 fluorine-free oxyalkylene units, said units being the same or different from one another and being selected from CH.sub.2CH.sub.2O and CH.sub.2CH(J)O, wherein J is a straight or branched alkyl or aryl; R.sub.b and R.sub.c are independently a hydrogen, a methyl or a benzyl group, with the proviso that R.sub.b and R.sub.c cannot be both hydrogen; X is a chlorine, a bromine or a iodine atom; A is R.sub.aC(?O)C(R.sub.bR.sub.c)X, wherein R.sub.a, R.sub.b, R.sub.c, and X are as defined above, or is a straight or branched C.sub.1-C.sub.4(per)fluoroalkyl group wherein one fluorine atom can be substituted by one chlorine atom or one hydrogen atom, such as, for example, a polymer of formula R.sub.f[CF.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.nC(?O)C(CH.sub.3).sub.2Br].sub.2 (n=0 to 6); a surfactant of formula R.sub.f1C.sub.2H.sub.4SO.sub.3Cat (2), wherein R.sub.f1 represents a perfluorinated aliphatic group and Cat represents a cation; a partially fluorinated surfactant of the general formula R.sub.f(CH.sub.2).sub.m6R.sub.fCOOY.sup.1 (3), wherein R.sub.f represents a perfluoroalkyl group or a perfluoroalkoxy group of 3 to 8 carbon atoms, R.sub.f represents a perfluoroalkylene of 1 to 4 carbon atoms, Y.sup.1 is NH.sub.4, Li, Na, K or H, or a linear, branched or cyclic alkyl containing 1-8 carbon atoms, and m6 is 1-3; R.sub.f(CH.sub.2).sub.n6COOM (4), where R.sub.f represents a perfluoroalkyl group or a perfluoroalkoxy group of 3 to 18 carbon atoms, n6 is from 0 to 2 and M is a monovalent cation. In case n6 is 0, R.sub.f represents a perfluoroalkyl group of 3 to 18 carbon atoms; a fluorinated surfactant of general formula R.sub.f(CH.sub.2).sub.n7(OCH.sub.2CH.sub.2).sub.m7OH (5), where R.sub.f represents a perfluoroalkyl group or a perfluoroalkoxy group of 3 to 18 carbon atoms, n7 is from 0 to 2, and m7 is from 0 to 5; in case n7 is 0, R.sub.f represents a perfluoroalkyl group of 3 to 18 carbon atoms; a perfluoropolyether of formula F(CF.sub.2).sub.m8O[CFX.sup.3CF.sub.2O].sub.n8CFX.sup.3COOA.sup.1 (6), wherein m8 is 1 to 5, X.sup.3 is F or CF.sub.3, A.sup.1 is a monovalent cation and n8 is 0 to 10; a fluorinated polyether of the formula F(CF.sub.2).sub.m8O[CFXCF.sub.2O].sub.n8CFX.sup.5COOA.sup.3 (7), wherein m8 is 3 to 10, X.sup.5 is F or a perfluoroalkyl group, n8 is 0, 1 or 2 and A.sup.3 is the counter ion of the carboxylic anion; a fluorinated polyether surfactant of formula R.sub.f2OCF.sub.2CF.sub.2X.sup.4 (8), wherein R.sub.f2 represents a linear or branched perfluoroalkyl group having 1, 2, 3 or 4 carbon atoms and X.sup.4 represents a carboxylic acid group or salt thereof; H(OCH.sub.2CH.sub.2).sub.kOCH.sub.2CF.sub.2(OCF.sub.2).sub.l(OCF.sub.2CF.sub.2).sub.m9OCF.sub.2CH.sub.2(OCH.sub.2CH.sub.2).sub.n9OH (9), wherein k is 0, 1 or 2, 1 is 2 to 150, m9 is 1 to 100, n9 is 0, 1 or 2; and mixtures thereof.

24. The composition according to claim 16, wherein the silver nanoplatelets bear a surface stabilizing agent on their surface, which is selected from surface stabilizing agents of formula ##STR00077## wherein R.sup.1 is H, C.sub.1-C.sub.18alkyl, phenyl, C.sub.1-C.sub.8alkylphenyl, or CH.sub.2COOH; R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are independently of each other H, C.sub.1-C.sub.8alkyl, or phenyl; Y is O, or NR.sup.8; R.sup.8 is H, or C.sub.1-C.sub.8alkyl; k1 is an integer in the range of from 1 to 500, k2 and k3 are independently of each other 0, or integers in the range of from 1 to 250; k4 is 0, or 1, k5 is an integer in the range of from 1 to 5, or surface stabilizing agents of formula ##STR00078## wherein R.sup.1 is H, or a C.sub.1-C.sub.8alkyl group, and k1 is 22 to 450; and surface stabilizing agents which are polymers, or copolymers, which are obtained by a process comprising the steps i1) polymerizing in a first step one or more ethylenically unsaturated monomers in the presence of at least one nitroxylether having the structural element ##STR00079## wherein X represents a group having at least one carbon atom and is such that the free radical X.Math. derived from X is capable of initiating polymerization; or i2) polymerizing in a first step one or more ethylenically unsaturated monomers in the presence of at least one stable free nitroxyl radical ##STR00080## and a free radical initiator; wherein at least one monomer used in the steps i1) or i2) is a C.sub.1-C.sub.6alkyl or hydroxyC.sub.1-C.sub.6alkyl ester of acrylic or methacrylic acid; and optionally ii) a second step, comprising the modification of the polymer or copolymer prepared under i1) or i2) by a transesterification reaction, an amidation, hydrolysis or anhydride modification or a combination thereof, or by copolymers represented by formula ##STR00081## wherein R.sup.11 and R.sup.12 are H or methyl, m, n and p are independently of each other integers from 1 to 200, o is an integer from 1 to 150; and mixtures thereof.

25. The composition according to claim 16, which comprises one, or more stabilizing agents selected from the group consisting of compounds of formula ##STR00082## wherein R.sup.21a is a hydrogen atom, a halogen atom, a C.sub.1-C.sub.8alkoxy group, or a C.sub.1-C.sub.8alkyl group, R.sup.21b is a hydrogen atom, or a group of formula CHR.sup.24N(R.sup.22)(R.sup.23), R.sup.22 and R.sup.23 are independently of each other a C.sub.1-C.sub.8alkyl, a hydroxyC.sub.1-C.sub.8alkyl group, or a group of formula [(CH.sub.2CH.sub.2)O].sub.n1CH.sub.2CH.sub.2OH, wherein n1 is 1 to 5, R.sup.24 is H or C.sub.1-C.sub.8alkyl, and compounds of formula ##STR00083## wherein R.sup.25 can be the same, or different in each occurrence and is a hydrogen atom, a halogen atom, a C.sub.1-C.sub.18alkyl group, a C.sub.1-C.sub.18alkoxy group, or a group C(?O)R.sup.26, R.sup.26 is a hydrogen atom, a hydroxy group, a C.sub.1-C.sub.18alkyl group, unsubstituted or substituted amino group, unsubstituted or substituted phenyl group, or a C.sub.1-C.sub.18alkoxy group, and n3 is a number of 1 to 4, m3 is a number of 2 to 4, and the sum of m3 and n3 is 6.

26. A security, or decorative element, comprising a substrate, which may contain indicia or other visible features in or on its surface, and on at least part of the said substrate surface, a coating, comprising the composition according to claim 16.

27. A security, or decorative element, comprising a substrate, which may contain indicia or other visible features in or on its surface, and on at least part of the said substrate surface, a coating, comprising the composition according to claim 16, wherein the security element, or decorative element comprises a substrate, a coating on at least a portion of the substrate comprising at least one liquid crystal compound, the coating being applied on the reverse side of the substrate if the substrate is transparent or translucent or on the surface side if the substrate is transparent, translucent, reflective or opaque and a further coating on at least a portion of the coating containing the liquid crystal compound or direct on the substrate if the coating containing the liquid crystal compound is placed on the reverse side of the substrate, the further coating is formed by the composition according to claim 16; or the security element, or decorative element consists of a multi-layer structure capable of interference, wherein the multilayer structure capable of interference has a reflection layer, a dielectric layer, and a partially transparent layer, wherein the dielectric layer is arranged between the reflection layer and the partially transparent layer, wherein the reflection layer is formed by a colored layer, comprising the composition according to claim 16; or the security element, or decorative element comprises a transparent carrier substrate, a layer containing a diffractive optical element (DOE) and a semi-transparent functional layer, which is formed by the composition according to claim 16; or the security, or decorative element is a blister for tablets, comprising a transparent carrier substrate that includes a semi-transparent functional layer, which is formed by the composition according to claim 16; or the security, or decorative element is a packaging comprising a plastic film shaped part and a cover film, wherein said plastic film shaped part defines the front side of the packaging and the cover film defines the rear side of the packaging, and the cover film is based on a carrier substrate provided with a semi-transparent functional layer, which is formed by the composition according to claim 16; or a security, or decorative element, comprising a substrate, a component with refractive index modulation, in particular a volume hologram, which is obtainable by exposing a recording material to actinic radiation and thereon a coating on at least a portion of the refractive index modulated layer, which is formed by the composition according to claim 16; or a security, or decorative element, comprising a substrate, an UV lacquer layer on at least part of the substrate having on at least part of its surface a nano- or microstructure, and on at least part of the UV lacquer layer and/or on at least part of the nano- or microstructure layer a coating, which is formed by the composition according to claim 16; or a security, or decorative element, capable of interference in the visible range of spectrum, comprising a substrate, optionally, carrying on at least part of its surface a nano- or microstructure, and on at least part of the substrate and/or on at least part of the nano- or microstructure, a coating, which is obtained with the compositions according to claim 16, said coating showing an interference color; or a security or decorative element, comprising i) a reflective layer, which is obtained with the compositions according to claim 16, ii) a transparent or translucent spacer layer and iii) additionally a transparent or translucent layer having a refractive index differing from refractive index of said spacer layer by at least 0.1; wherein the spacer layer ii) is located between the reflective layer i) and the layer iii) and the security, or decorative element showing an interference color.

28. A product, comprising the security or decorative element according to claim 26.

29. Use of the security or decorative element according to claim 26 for the prevention of counterfeit or reproduction, on a document of value, right, identity, a security label or a branded good.

30. A method for manufacturing of a security or decorative element, comprising the steps of: a) providing a substrate, optionally bearing a surface relief nano- or microstructure, b1) applying a composition claim 16 to at least a portion of the substrate, b2) optionally embossing a nano- or microstructure into the coating obtained in step b1), and c) curing the composition with actinic radiation.

Description

EXAMPLES

[0664] UV-Vis spectra of dispersions were recorded on Varian Cary 50 UV-Visible spectrophotometer at such concentration of dispersions as to achieve the optical density of 0.3 to 1.5 at 1 cm optical path.

[0665] TEM analysis was conducted on dispersions containing silver nanoplatelets in isopropanol using an EM 910 instrument from ZEISS, INST.109, in bright field mode at an e-beam acceleration voltage of 100 kV. At least 2 representative images with scale in different magnification (5,000?, 10,000? and 20,000?) were recorded in order to characterize the dominant particle morphology for each sample.

[0666] The number mean diameter of the silver nanoplatelets refers to the mean diameter determined by transmission electron microscopy (TEM) using Fiji image analysis software (or Image analysis software: ParticleSizer (Thorsten Wagner (2016) ij-particlesizer: ParticleSizer 1.0.9. Zenodo; 10.5281/zenodo.820296) and ImageJ version 1.53f51) based on the measurement of at least 300, especially at least 500 randomly selected silver nanoplatelets oriented parallel to the plane of a transmission electron microscopy image (TEM), wherein the diameter of a silver nanoplatelet is the maximum dimension of said silver nanoplatelet (maximal Feret diameter) oriented parallel to the plane of a transmission electron microscopy (TEM) image (recorded at magnification 20,000?).

[0667] The number mean thickness of silver nanoplatelets refers to the mean thickness determined by transmission electron microscopy (TEM) based on the measurement of at least 50, especially of at least 300 randomly selected silver nanoplatelets oriented perpendicular to the plane of the TEM image (recorded at magnification 25,000?), wherein the thickness of the silver nanoplatelet is the maximum thickness of said silver nanoplatelet. TEM analysis was conducted on dispersions containing silver nanoplatelets in isopropanol using an EM 910 instrument from ZEISS, INST.109, in bright field mode at an e-beam acceleration voltage of 100 kV.

[0668] In detail, a part of the dispersion is transferred to a smooth foil. After drying the sample is embedded in Araldit?, which is cross-linked below 60? C. Ultrathin cross-sections of the embedded sample are prepared perpendicular to the foil surface. The thickness of at least 300 randomly selected silver nanoplatelets may be determined from the cross-sectional TEM images (recorded at magnification 25,000?) by fitting ellipses to the cross-sectioned particles by the software (ParticleSizer). The minor axis (the shortest diameter) of the fitted ellipse is taken as particle thickness.

Synthesis Example 1Preparation of S-Vinylmercaptoethanol (VME) Ethoxylate

[0669] VME-ethoxylate is synthesized essentially according to Example 1h, described in EP3063188B1, with the reactant ratios described in Table 1.

TABLE-US-00001 S-vinylmercaptoethanol (VME) 25 g Potassium methylate 0.25 g Toluene 75 g Ethylene oxide 1160 g

[0670] The product had hydroxyl value of 25.5 mg KOH/g.

Synthesis Example 2Hydrolysis of VME-Ethoxylate

[0671] 844 g of VME-ethoxylate are dissolved in 770 g of de-ionized water and the temperature is brought to 50? C. 26.85 g of silver nitrate are dissolved in 50.7 g water and the resulting solution is added to the solution of VME-ethoxylate in one portion. The mixture is stirred at 50? C. for 5 min, followed by addition of 37.5 g of methanesulfonic acid. The resulting mixture is stirred for 8 h at 50? C. and then pH was brought to ca. 5 by dropwise addition of 47.5 g of 50% w/w solution of NaOH in de-ionized water. The resulting solution, containing silver complex of O-(2-mercaptoethyl)-poly(ethylene glycol), is stored at room temperature and used for the synthesis of silver nanoplatelets without further purification.

Synthesis Example 3Urethane Acrylate (UA-1)

[0672] In a four-necked flask, equipped with reflux condenser, stirrer, dropping funnel and thermometer was provided, 550 g Pluriol? 1010 E (product of BASF SE, polyethylene oxide having molecular weight 1000 g/mol), 0.9 g dimethylolpropionic acid, 102.1 g 2-hydroxyethyl acrylate, 290.4 g dipropylene glycol diacrylate (Laromer? DPGDA, commercial product of BASF SE), 0.9 g 2.6-di-tert-butyl-p-cresol and 0.44 g methyl hydroquinone were mixed at 60? C. 0.6 dibutyltin dilaurate were added as catalyst. 201 154.5 g tolylene diisocyanate (mixture of 2.4 and 2.6 isomers) (Lupranat? T80, product of BASF SE) were added drop wise to this mixture at 60 to 70? C. within 60 minutes.

[0673] Then the reaction mixture was stirred at ca. 65? C. (internal temperature) for 6 hours until the NCO value of the reaction mixture was 0.25%. Then 23.2 g dibutylamine were added and the reaction mixture was stirred at 65? C. for 2 h. The obtained polymer was then diluted with 174 dipropylene glycol diacrylate (Laromer? DPGDA, commercial product of BASF SE).

[0674] The content of the urethane acrylate in the reactive diluent was 65%. The double bond density of solvent-free urethane acrylate 1.03 moles/kg of urethane acrylate and the viscosity of the reaction mixture was 7.5 Pa s.

Example 1 (cf. Example 1 of WO2020/083794)

a) Synthesis of Silver Nanoplatelets

[0675] Preparation of Solution A: 925 g of the solution, obtained in Synthesis Example 2, are mixed with 250 g of de-ionized water. Separately, 720.5 g of silver nitrate are dissolved in 450 g of deionized water and both solutions are mixed at room temperature. 485.6 g of diethylenetriamine are added dropwise, while maintaining the temperature between 25 at 30? C. After the addition is complete, 211 g of 25% w/w ammonia solution in water and 114 g of methylglycine diacetic acid trisodium salt, 40% w/w solution in water, are added and the resulting solution is cooled to ca. +3? C.

[0676] Preparation of Solution B: 1170 g of de-ionized water are placed in a reactor and stirred at room temperature under vacuum (100 mbar) for 10 min. Vacuum is released with nitrogen gas, and the procedure is repeated another 2 times for removing the dissolved oxygen. Then 53 g of hydrazine monohydrate is added, followed by addition of 42.4 g of 25% w/w ammonia solution in water and the solution temperature is brought to 45? C. After that, 2 g of 1-octanol and 0.5 g of borane-morpholine complex are added and the mixture is stirred for 5 min at 45? C.

[0677] The whole amount of Solution A is dosed into Solution B with a constant rate over 75 min under the surface, while maintaining the temperature of Solution B at 45? C., resulting in a dispersion of silver nanoplatelets (total silver concentration 10.4% w/w).

b) Isolation and Purification

[0678] The dispersion is cooled to 25? C., then 24 g of cpd. (B-3) are added to the dispersion and the stirring is continued for 1 h. The stirrer is stopped and the dispersion is allowed to sediment for 24 h at room temperature. Then 2300 g of supernatant are pumped out with a peristaltic pump, 2200 g of de-ionized water are added and the mixture is stirred for 1 h at room temperature. After that, 230 g of anhydrous sodium sulfate are added in portions with stirring. Stirring is continued for 20 min after addition of last portion of sodium sulfate, the stirrer is stopped and the dispersion is allowed to sediment for 24 h at room temperature. Then 2900 g of supernatant are pumped out with a peristaltic pump, 1000 g of de-ionized water are added and the mixture is stirred for 1h at RT.

[0679] The dispersion is subjected to ultrafiltration with an Al.sub.2O.sub.3 membrane (50 nm pore size) until the conductivity of the permeate dropped below 10 ?S/cm.

[0680] Yield: 2360 g of silver nanoplatelets dispersion in water. Dry content of silver nanoplatelets in the resulting dispersion is 19.4% w/w, yield of silver nanoplatelets (based on total silver, introduced in reaction) is 90%.

[0681] Highest wavelength absorption maximum of the obtained silver nanoplatelets is located at 490 nm, when measured in water at ca. 5*10.sup.?5 M concentration of silver). FWHM of this maximum is 85 nm.

[0682] Mean diameter of the particles is 45?10 nm. Mean thickness of the particles is 18?2.4 nm (standard deviation is indicated after ?sign).

c) Solvent Switch

[0683] 100 g of dispersion of silver nanoplatelets in water, obtained in step b) were placed in a round-bottom flask and the solution of 0.7 g of ethyl gallate in 200 g of 1-methoxy-2-propanol is added. The mixture is concentrated on rotary evaporator to ca 40% w/w of dry content, then 100 g of 1-methoxy-2-propanol are added and the mixture is concentrated again to ca. 40% w/w of dry content. 100 g of 1-methoxy-2-propanol are added and the mixture is concentrated to ca. 45% w/w of dry content and filtered through Whatman Grande GF/B=1u filter. The dry content in filtrate is adjusted to 40% w/w by addition of 1-methoxy-2-propanol.

Example 2 (Cf. Example 1 of WO2020/224982)

[0684] a) In a 1 L double-wall glass reactor, equipped with anchor-stirrer, 365 g of de-ionized water was cooled to +2? C. 13.62 g of sodium borohydride was added, and the mixture was cooled to ?1? C. with stirring at 250 rounds per minute (RPM, Solution A).

[0685] In a 0.5 L double-wall glass reactor, equipped with anchor-stirrer, 132 g of deionized water and 4.8 g of MPEG-5000-thiol were combined, and the mixture was stirred for 10 minutes at room temperature. 72 g of the product of Example A3 of WO2006074969 was added, and the resulting mixture was stirred for another 10 minutes at room temperature for homogenization. The solution of 30.6 g of silver nitrate in 30 g of de-ionized water was added in one portion and the mixture was stirred for 10 minutes, resulting in an orange-brown viscous solution. To this solution 96 g of deionized water was added, followed by addition of 3 g of Struktol SB2080 defoamer, pre-dispersed in 36 g of de-ionized water. The resulting mixture was cooled to 0? C. with stirring at 250 RPM (Solution B).

[0686] After that, Solution B was dosed with a peristaltic pump at a constant rate over 2 h into Solution A under the liquid surface via a cooled (0? C.) dosing tube, resulting in spherical silver nanoplatelets dispersion. During pumping, the Solution A was stirred at 250 RPM.

[0687] After dosing was complete, the reaction mixture was warmed up to +5? C. within 15 minutes, and a solution of 862 mg of KCl in 10 g of deionized water was added in one portion, followed by addition of 9.6 g of ethylenediaminetetraacetic acid (EDTA) in 4 equal portions with 10 minutes time intervals.

[0688] After addition of the last EDTA portion, the reaction mixture was stirred for 15 minutes at +5? C., then warmed up to 35? C. over 30 minutes and stirred for 1 h at this temperature. Upon this time, hydrogen evolution is completed.

[0689] 3.0 mL of 30% w/w solution of ammonia in water was added, followed by addition of 5.76 g of solid NaOH, and the mixture was stirred for 15 min at 35? C. Then 180 mL of 50% w/w hydrogen peroxide solution in water were dosed with a peristaltic pump at a constant rate over 4 h into the reaction mixture under the liquid surface with stirring at 250 RPM, while maintaining the temperature at 35? C. This has led to a deep blue colored dispersion of silver nanoplatelets, which was cooled to room temperature. 1.23 g of compound of formula (B-3) was added, and the mixture was stirred for 1 h at room temperature.

b) Isolation and Purification of Ag Nanoplatelets

b1) Decantation

[0690] 9.6 g of sodium dodecylsulfate was added to the reaction mixture and then ca. 25 g of anhydrous sodium sulfate powder was added in portions with stirring until the transmission color of the dispersion changed from blue to pink. Then the mixture was kept without stirring at room temperature for 24 h, allowing the coagulated nanoplatelets to sediment at the bottom of the reactor.

[0691] 890 g of supernatant was pumped out from the reactor with a peristaltic pump, and 890 g of deionized water was added to the reactor. The mixture in reactor was stirred for 1 h at room temperature, allowing the coagulated particles to re-disperse.

b2) Decantation

[0692] Ca. 64 g of anhydrous sodium sulfate powder was added in portions with stirring until the transmission color of the dispersion changed from blue to yellowish-pink. Then the mixture was kept without stirring at room temperature for 12 h, allowing the coagulated nanoplatelets to sediment at the bottom of the reactor. 990 g of supernatant was pumped out from the reactor with a peristaltic pump, and 90 g of deionized water was added to the reactor. The resulting mixture was stirred for 30 minutes at room temperature, allowing the coagulated particles to re-disperse.

b3) Ultrafiltration in Water

[0693] The resulting dispersion of Ag nanoplatelets was subjected to ultrafiltration using a Millipore Amicon 8400 stirred ultrafiltration cell. The dispersion was diluted to 400 g weight with de-ionized water and ultrafiltered to the end volume of ca. 50 mL using a polyethersulfone (PES) membrane with 300 kDa cut-off value. The procedure was repeated in total 4 times to provide 60 g of Ag nanoplatelets dispersion in water. After ultrafiltration was completed, 0.17 g of compound (B-3) was added to the dispersion. Ag content 28.9% w/w; yield ca. 89% based on total silver amount; Solids content (at 250? C.) 33.5% w/w; Purity 86% w/w of silver based on solids content at 250? C.

b4) Ultrafiltration in Isopropanol

[0694] The dispersion was further ultrafiltered in isopropanol. 60 g of Ag nanoplatelets dispersion, obtained after ultrafiltration in water, was placed in a Millipore Amicon 8400 stirred ultrafiltration cell and diluted to 300 g weight with isopropanol. The dispersion was ultrafiltered to the volume of ca. 50 mL using a polyethersulfone (PES) membrane with 500 kDa cut-off value. The procedure was repeated in total 4 times to provide 72 g of Ag nanoplatelets dispersion in isopropanol.

[0695] Ag content 24.1% w/w; Solids content (at 250? C.) 25.7% w/w; Purity 93.5% w/w of silver based on solids content at 250? C.

[0696] The UV-Vis-NIR spectrum was recorded in water at Ag concentration of 9.8*10.sup.?5 M.

[0697] ?.sub.max=700 nm; extinction coefficient at maximum ?=10200 L/(cm*mol Ag), FWHM=340 nm.

[0698] Reference is made to FIG. 1. UV-Vis-NIR spectrum of Ag nanoplatelets from Example 1 b4). Number mean particle diameter 93+40 nm, number mean particle thickness 16?2.5 nm.

Example 3Replacement of Solvent with Dipropylene Glycol Diacrylate (DPGDA)

[0699] 100 g of the dispersion, prepared according to Step c) of Example 1, was placed in a 0.5 L round-bottom flask and 50 g of DPGDA was added. 1-methoxy-2-propanol was removed on rotary evaporator at 10 mbar pressure and 50? C. bath temperature, until no more solvent was distilled off. The solids content was adjusted to 42% by addition DPGDA to obtain the dispersion of silver nanoplatelets in DPGDA.

[0700] The dispersion of silver nanoplatelets in DPGDA was mixed with additional radically curable components and photoinitiator and homogenized thoroughly to obtain coating compositions 1 to 4. Reference is made to Table 1.

TABLE-US-00002 TABLE 1 Photoini- Component tiator (D) Ag NPs of (B) Com- Oligomer Omnirad? Example DPGDA.sup.2) ponent (C) [% by 819.sup.1) Coating 3 [% by [% by (E) [% by weight] [% by Comp. weight] weight] weight] UA-1.sup.3) weight] 1 8.7 52.7 33.9 4.7 2 8.7 30.2 22.5 33.9 4.7 TPGDA.sup.4) 3 8.7 30.2 22.5 33.9 4.7 HDDA.sup.5) 4 8.7 30.2 22.5 33.9 4.7 Divinyl ad..sup.6) .sup.1)Omnirad? 819 = phenyl-bis(2,4,6-trimethylbenzoyl)phosphine oxide .sup.2)DPGDA = dipropylene glycol diacrylate .sup.3)UA-1 = Urethane Acrylate obtained in Synthesis Example 3, excluding DPGDA .sup.4)TPGDA = tripropylene glycol diacrylate .sup.5)Laromer? HDDA = 1,6-hexandiol diacrylate .sup.6)Divinyl adipate = CH.sub.2?CHOC(?O)(CH.sub.2).sub.4C(C?O)OCH?CH.sub.2

Example 4General Procedure for Preparation of Printing Compositions 5 to 11

[0701] The radically curable monomers and photoinitiator were mixed with the dispersion, obtained in Example 2, step b4) in such proportions, as to obtain the compositions shown in Table 2 after solvent removal. The resulting mixture was concentrated on rotary evaporator at 20 mbar pressure and 50? C. bath temperature, till no more solvent was distilled off to obtain the printing compositions 5 to 11. Reference is made to Table 2.

TABLE-US-00003 TABLE 2 Component Oligomer Photoinitiator Ag NPs (B) (C) [% (D) Surfactant of DPGDA.sup.2) by Omnirad? (G) Printing Example 3 [% by Component (E) weight] 819.sup.1) [% by Comp. [% by weight] weight] [% by weight] UA-1.sup.3) [% by weight] weight] 5 7.8 56.3 30.9 5.0 6 7.8 16.6 39.5 TPGDA.sup.4) 30.8 5.3 7 7.8 16.6 39.5 Laromer? 30.8 5.3 HDDA.sup.5) 8 7.8 16.6 39.5 30.8 5.3 Divinyl adipate.sup.6) 9 13.6 55.3 27.0 4.1 10 7.8 55.8 30.4 5.0 1.0.sup.7) 11 7.8 56.2 30.7 5.0 0.3.sup.8) .sup.1)Omnirad? 819 = phenyl-bis(2,4,6-trimethylbenzoyl)phosphine oxide .sup.2)DPGDA = dipropylene glycol diacrylate .sup.3)UA-1 = Urethane Acrylate obtained in Synthesis Example 3, excluding DPGDA .sup.4)TPGDA = tripropylene glycol diacrylate .sup.5)Laromer? HDDA = 1,6-hexandiol diacrylate .sup.6)Divinyl adipate = CH.sub.2?CHOC(?O)(CH.sub.2).sub.4C(C?O)OCH?CH.sub.2 .sup.7)Fluorolink? E10H .sup.8)Perfluorononanoic acid

[0702] The term Ag nanoplatelets in Application Examples 1 to 4 refers to total solids content (excluding DPGDA) of the dispersion, obtained in Example 3. The solids includes (surface) stabilizing agents, present in the dispersion and on the surface of Ag nanoplatelets.

[0703] The term Ag nanoplatelets in Application Examples 5 to 11 refers to total solids content of the dispersion, obtained in Example 2, Step b4). The solids include (surface) stabilizing agents, present in the dispersion and on the surface of Ag nanoplatelets.

Application Examples 1 to 4

[0704] Substrate preparation: Melinex 506 PET foil substrate was coated with a UV-curable varnish Lumogen OVD 311 (commercially available from BASF SE), using K bar wired handcoater #1 and the obtained coating was cured with a medium pressure Hg lamp (total UV dose ca. 500 mJ/cm.sup.2).

[0705] The coating compositions from Table 1 were coated onto thus prepared substrate using K bar wired handcoater #1 and cured with a medium pressure Hg lamp (total UV dose ca. 500 mJ/cm.sup.2). The properties of the obtained coatings are shown in Table 3.

TABLE-US-00004 TABLE 3 Application Example 1 2 3 4 Coating Composition Property 1 2 3 4 Color of coating green- green- green- green- (frontside of substrate) gold metallic gold gold Color of coating green- green- green- green- (backside of substrate) gold gold gold gold Reflection Intensity 4 3 4 4 (frontside of substrate) Reflection Intensity 4 4 4 4 (backside of substrate) Transmission Color magenta magenta magenta magenta Quality of Transmission Color 3 3 3 3 Adhesion 3 1 1 3

Application Examples 5 to 11

[0706] Substrate preparation: Melinex 506 PET foil substrate was coated with a UV-curable varnish Lumogen OVD 311 (commercially available from BASF SE), using K bar wired handcoater #1 and the obtained coating was cured with a medium pressure Hg lamp (total UV dose ca. 500 mJ/cm.sup.2).

[0707] The coating compositions from Table 2 were coated onto thus prepared substrate using K bar wired handcoater #1 and cured with a medium pressure Hg lamp (total UV dose ca. 500 mJ/cm.sup.2). The properties of obtained coatings are shown in Table 4.

TABLE-US-00005 TABLE 4 Application Example 5 6 7 8 9 10 11 Coating Composition Property 5 6 7 8 9 10 11 Color of coating gold gold gold gold gold gold gold (frontside of substrate) Color of coating gold gold gold gold gold gold gold (backside of substrate) Reflection Intensity 3 3 3 3 4 4 4 (frontside of substrate) Reflection Intensity 3 3 3 3 4 4 4 (backside of substrate) Transmission blue blue blue blue dark blue blue Color blue Quality of 3 3 3 3 3 3 3 Transmission Color Adhesion 3 3 3 3 3 3 3

Example 5. Replacement of Solvent with Dipropylene Glycol Diacrylate (DPGDA)

[0708] 50 g (12.85 g of solids) of dispersion, obtained in Example 2, Step b4) was placed in a 250 mL round bottom flask and DPGDA (30.0 g) was added. The resulting mixture was concentrated on rotary evaporator at 20 mbar pressure and 50? C. bath temperature, till no more solvent was distilled off. The solids content was adjusted to 25% w/w by addition of DPGDA.

Application Example 12

[0709] The dispersion of silver nanoplatelets in DPGDA obtained in Example 5 was mixed with additional radically curable components and photoinitiator and homogenized thoroughly to obtain printing composition 12. Reference is made to Table 5.

TABLE-US-00006 TABLE 5 Photoinitiator Ag NPs of Component Oligomer (D) Surfactant Example 5 (B) DPGDA.sup.2) Component (C) [% by Omnirad? (G) Printing [% by [% by (E) [% by weight] 819 [% by Comp. weight] weight] weight] UA-1 [% by weight] weight] 12 7.7 49.8 38.1 4.4

[0710] Printing composition 12 was printed with a flat-bed screen press Sirimac 4560E from Eickmeyer, using a 180/31Y (180 threads per cm, each with a nominal thread diameter of 31 ?m, yellow thread) screen with a certain printing image design and mercury UV lamp for curing. Prints were dried in an oven at 80? C. for 2 minutes, followed by UV curing at 120 W/cm, 20m/minute speed of a UV dryer belt. The properties of obtained prints are shown in Table 6.

TABLE-US-00007 Application Example 12 Coating Composition Property 12 Color of coating (frontside of substrate) gold Color of coating (backside of substrate) gold Reflection Intensity (frontside of substrate) 3 Reflection Intensity (backside of substrate) 3 Transmission Color blue Quality of Transmission Color 3

[0711] Reflectivity was assessed visually according to the grayscale from 1 to 4.

[0712] Quality of transmission color was assessed visually according to the grayscale from 1 to 3.

[0713] The strength of adhesion of coatings to substrate was assessed according to a grayscale from 1 to 3 via a simplified scotch tape test:

[0714] The coatings after UV curing were left under ambient conditions for 3 days, then an adhesive tape, Lyreco Invisible Tape 184.835, was firmly applied over a portion of a coating and rapidly peeled off.

[0715] The meanings of grey scale ratings for the tests of reflectivity, transmission color quality and adhesion of the coatings are summarized in Table 7.

TABLE-US-00008 TABLE 7 Meaning of grey scale ratings for the tests of reflectivity, transmission color quality and adhesion of the coatings Quality of Rating Reflection Transmission Color Adhesion 1 No metallic Grey color Coating is fully reflection removed from substrate with scotch tape 2 Weak colored Greyish magenta Coating is metallic aspect (Appl. Ex. 1-4) or partially removed blue (Appl. Ex. 5- from substrate 12) color with scotch tape 3 Strong colored Deep magenta (Appl. Coating is not metallic reflection Ex. 1-4) or blue removed from (Appl. Ex. 5-12) substrate with color, similar to the scotch tape color of particles dispersion in THF 4 Very strong colored metallic reflection