Perylene-based UV-curable security ink composition

Abstract

The present invention relates to the field of UV-curable security ink compositions comprising a perylene-based compound, a free-radical curable monomer, an oligomer or a mixture thereof, and a free-radical photoinitiator. The invention further relates to a security feature obtained by applying or printing the security ink composition, an article or document containing said security feature and a method of making a security feature comprising the UV-curable security ink composition.

Description

Technical Field

[0001] The present invention relates to the following fields: UV curable security ink compositions based on rylene-based compounds, their use in security printing inks, and security features based on such security inks. Background Art

[0002] With the continuous improvement of the quality of color copying and printing technologies and the attempt to protect security documents such as banknotes, valuable documents or cards, transportation tickets or cards, tax banderols, and product labels, it has been a traditional practice to introduce various security features into these documents to resist replicability and prevent forgery, tampering, or illegal copying.

[0003] With the increasing threat of forgery of security documents such as currency, passports, or identity cards around the world, this situation has become a very critical issue for governments and society as a whole. For example, criminal organizations may use fake passports or identity cards to traffic people. As copying technologies become more and more sophisticated, it becomes more difficult to make a clear distinction between fake documents and original documents. Therefore, document security has a considerable impact on the economies of various countries and the victims of illegal trafficking involving forged documents.

[0004] Security features have also been introduced into (excise) stamps. The main purpose of these stamps is to provide the government with a physical means of levying taxes. Other purposes may be to provide a tamper / reuse-proof seal or as a carrier for serialized codes for item-level production monitoring and supply chain tracking and tracing.

[0005] Therefore, security features are introduced into documents to ensure their integrity. Security features can generally be classified on the one hand as "hidden" security features and on the other hand as "visible" security features. The protection provided by hidden security features relies on the concept that such features are difficult to detect and usually require professional equipment and knowledge for detection, while "visible" security features rely on the concept that they can be easily detected by the unaided human senses. For example, such features can be visible and / or detectable via the tactile sense, while still being difficult to produce and / or replicate. However, the effectiveness of visible security features depends to a large extent on their easy recognition as security features, because most users, especially those who are not previously aware of the security features of the documents or items protected by security features, will only conduct a security check based on the security features when they actually know the existence and nature of the security features.

[0006] UV curable ink compositions are known in the art and are widely used to impart security features. These are cured by rapid photoinduced polymerization. Since the UV curing process is substantially solvent-free, the need for time-consuming and expensive pollution elimination procedures is greatly reduced.

[0007] UV curable ink compositions offer several other benefits independent of thermally cured coatings. First, faster curing times provide significant economic benefits. In addition, heat-sensitive materials can be safely coated and cured with UV light without thermal degradation of the heat-sensitive substrate. Further, due to the widespread availability of UV light, it is a relatively low-cost energy source.

[0008] To impart a specific color to the UV curable ink composition, various pigments and dyes can be added. Such pigments and dyes are based on a large number of different chemical structures.

[0009] Fluorescent perylene-based dyes or pigments are known in the art for use in high-end covert security features (e.g., US20080167467). These compounds are mainly based on a perylene substructure, as described below. Examples of perylene-based dyes or pigments are perylenes, terrylenes, and quaterrylenes.

[0010] It is known to introduce polymer-grafted perylene-based compounds into security ink compositions. For example, WO2011 / 147857A1 discloses perylene-based printing ink compositions, while WO 2012 / 160182 A1 discloses terrylene-based and quaterrylene-based ink compositions. The solubility of prior art perylene dyes is increased by covalently grafting polymer phenolic groups to the perylene substructure. However, perylene-based dyes still suffer from various problems such as insufficient fluorescence, insufficient lightfastness, and poor solubility in ink compositions. In particular, up to 15 wt% amounts of polymer-grafted perylene-based compounds may be required in the colored ink composition to ensure good detection. Their high amounts and incompatibility with monomers and / or oligomers used in UV curable ink compositions result in deteriorated printing properties.

[0011] In addition to the above, it is always necessary to ensure good and uniform printability of the security ink composition and avoid (visible) printing defects while ensuring easy and reliable detection of the security feature using existing equipment. An additional economic benefit is to ensure the addition of a minimum amount of (perylene-based) dye or pigment to the ink composition to ensure the uniformity and better printability of the ink composition.

[0012] Accordingly, there is still a need for UV curable ink compositions that overcome the deficiencies of the prior art. SUMMARY OF THE INVENTION

[0013] In one aspect, the present invention relates to a UV-curable safety ink composition comprising:

[0014] a) about 40 to about 95% by weight, preferably about 60 to 95% by weight, of one or more free-radical curable monomers, one or more oligomers, or mixtures thereof;

[0015] b) about 0.1 to about 20% by weight, preferably about 1 to 15% by weight, of at least one free-radical photoinitiator;

[0016] c) about 0.005 to about 5% by weight, preferably about 0.01 to 1% by weight, of at least one compound P, wherein P is a compound having a structure selected from the group consisting of (1) and (2)

[0017]

[0018] wherein

[0019] (W) is a perylene substructure, which preferably comprises any one of a perylene, triphenylene or quaterrylene nuclear structure and comprises at least one substituent of formula (3) attached to the perylene substructure (W),

[0020]

[0021] R 1 、R 2 、R 3 are independently a carbocyclic or heterocyclic substituent, wherein R 1 and R 2 are attached to, preferably directly attached to, the imide N of the perylene substructure (W), and in the case of compound (2), R 3 is directly attached to the naphthalene ring; and

[0022] wherein

[0023] ----- represents an optionally present R 3 substituent,

[0024] Ar 4 is an aromatic substituent,

[0025] Y is a linker,

[0026] R’ is H or methyl;

[0027] d) optionally about 0.1 to about 2% by weight of at least one photosensitizer;

[0028] e) optionally about 0.1 to about 20% by weight of at least one colorant;

[0029] f) Optionally, at least one additive in an amount of from about 0.01 to about 10% by weight, preferably at least one surfactant in an amount of from about 0.01 to about 1% by weight;

[0030] % by weight is based on the total weight of the UV-curable security ink composition.

[0031] In another aspect, the present invention relates to a security feature made of a cured layer of the UV-curable security ink composition described herein.

[0032] In another aspect, the present invention relates to a security document or article comprising the security feature described herein.

[0033] In yet another aspect, the present invention relates to a method for preparing the security feature described herein, which comprises the following steps:

[0034] a) applying the UV-curable security ink composition described herein to a substrate, preferably by a printing process; and

[0035] b) at least partially curing the UV-curable security ink composition from step a), wherein the curing is preferably carried out using a UV-LED light source, more preferably having a wavelength of from about 360 nm to about 410 nm. Description of the Drawings

[0036] Figure 1 Shows a security feature in the form of a QR code obtained by printing a UV-curable security ink composition as described herein. Detailed Description

[0037] Definitions

[0038] The following definitions are used to clarify the meaning of the terms discussed in the specification and defined in the claims.

[0039] As used herein, the indefinite article "a" means one as well as more than one, and does not necessarily limit the noun it designates to being singular.

[0040] As used herein, the term "about" means that the quantity or value in question can be the specified value or some other value near it. The phrase is intended to express that similar values within ±5% of the stated value produce equivalent results or effects according to the present invention.

[0041] As used herein, the term "UV" (ultraviolet) is intended to mean irradiation having a wavelength component in the UV part of the electromagnetic spectrum; typically from 200 nm to 420 nm.

[0042] As used herein, the term "at least one" is intended to define one or more than one, such as one or two or three.

[0043] As used herein, the term "and / or" means that all or only one of the elements of the group may be present. For example, "A and / or B" shall mean "only A, or only B, or both A and B". In the case of "only A", the term also covers the possibility that B is absent, i.e., "only A without B".

[0044] As used herein, the term "comprising" is intended to be non-exclusive and open-ended. Thus, for example, a coating composition comprising compound A may include other compounds in addition to A. However, as a specific embodiment thereof, the term "comprising" also covers the more restrictive meanings of "consisting essentially of" and "consisting of", such that, for example, "a fountain solution comprising A, B and optionally C" may also (essentially) consist of A and B or (essentially) consist of A, B and C.

[0045] The term "secure document" refers to a document that is usually protected against forgery or fraud by at least one security feature. Examples of secure documents include, but are not limited to, valuable documents and valuable goods.

[0046] The term "security feature" is used to denote an image, pattern or graphic element that can be used for authentication purposes.

[0047] In cases where this specification refers to "preferred" embodiments / features, combinations of these "preferred" embodiments / features should also be considered disclosed, provided that such combinations of "preferred" embodiments / features are technically meaningful.

[0048] The term "perylene substructure" is used to denote the general structure shown below. As used herein, the term "perylene substructure" includes perylene-based compounds such as perylene, terrylene and quaterrylene moieties or even pentarylene and hexarylene derivatives. For the sake of clarity, the perylene substructure means a perylene nucleus having two diimide moieties (such as perylene), as exemplarily shown below.

[0049]

[0050] The term "Ar" is used to denote an aromatic substituent.

[0051] The term "wt%" represents the amount of the component based on the total weight of the UV-curable security ink composition.

[0052] The present invention provides a UV-curable security ink composition comprising at least one compound P as described herein.

[0053] P is a compound having a structure selected from the group consisting of (1) and (2):

[0054]

[0055] In one embodiment, as described herein, (W) is a perylene substructure, which preferably comprises any one of a perylene, a triphenylene or a quaterrylene core structure and comprises at least one substituent of formula (3):

[0056]

[0057] In a preferred embodiment, the perylene substructure (W) may be selected from the group consisting of a perylene, a triphenylene or a quaterrylene core structure, wherein the core structure bears two diimide moieties.

[0058] At least one substituent (3) is attached to the perylene substructure. Preferably, the substituents (3) are attached to the perylene, triphenylene or quaterrylene core structure at their corresponding naphthalene rings. It will be apparent to those skilled in the art that the placement of at least one substituent (3) on the naphthalene rings of the perylene substructure (W) can only occur at chemically possible positions. The perylene substructure (W) may accommodate a plurality of substituents (3) on different naphthalene rings of the perylene substructure (W), i.e., perylene substructures having two (diacrylate) or more (polyacrylate) substituents (3) are contemplated. Thus, isomeric perylene substructures (W) having substituents (3) are possible. As a result, even mixtures of isomeric substituted perylene substructures (W) are possible. In a preferred embodiment, there are at least two substituents (3) (i.e., diacrylates) on the perylene substructure (W).

[0059] At least one substituent (3) has the structure as shown above. Ar 4 The substituent may be any aromatic group. Preferably, Ar 4 group is a benzene ring. The benzene ring may or may not be substituted. If substituted, the benzene ring may further comprise C1-C6 alkyl and its isomers as substituents.

[0060] At least one substituent (3) further comprises a linker Y. The linker Y may be selected from the group consisting of -(CH2) j -, -O-(CH2) k -, -[-(CH2) l -O] m -(CH2) p and wherein j = 0 to 6, k = 1 to 6, l = 1 to 3, m = 1 to 3, p = 1 to 3. Preferably, the linker Y contains at least one -(CH2) j - group, wherein j = 1 to 6, connecting the Ar 4 moiety to the O atom as shown in formula (3).

[0061] At least one substituent (3) further contains at least one (meth)acrylate moiety. In a preferred embodiment, at least one substituent (3) contains one (meth)acrylate moiety. The group R’ can be hydrogen or methyl.

[0062] In another embodiment, at least one compound P can have structure (2) as described herein. As shown structurally, compared to the perylene substructure (W), the compound P having formula (2) lacks an imide moiety. Instead of the missing imide moiety, the compound (2) can be substituted with different substituents R 3 substituted. The structure (2) shown demonstrates this with a ---- bond pattern. Thus, the R 3 substituent is optional.

[0063] At least one compound P having structure (2) further comprises at least one substituent (3) as described herein. It should be noted that the position of at least one substituent (3) as shown in formula (2) is merely exemplary. Thus, it is not excluded that at least one substituent (3) is bonded to another naphthalene ring of the nuclear structure of formula (2). As previously mentioned, for the perylene substructure (W), there can even be more than two substituents (3). In a specific embodiment, at least one substituent (3) as described herein can be present at the position of the R 3 substituent. In this case, the R 3 substituent is absent, i.e., at least one substituent (3) replaces the R 3 substituent.

[0064] At least one compound P further comprises R 1 , R 2 or R 3 substituents, where the R 1 , R 2 and R 3 substituents are independently carbocyclic or heterocyclic substituents. In the case of R 1 and R 2 , the substituents are attached to, preferably directly attached to, the imide N of the perylene substructure (W), while in the case of R 3 , the substituent is optional and can be directly attached to the naphthalene ring as shown in formula (2).

[0065] The carbocyclic substituents R 1 , R 2 or R 3 can be selected from the group consisting of alicyclic and aromatic substituents, optionally bearing further substituents. Preferably, the substituents R 1 , R 2 or R 3Essentially aromatic and optionally substituted. Thus, in a preferred embodiment, R 1 is Ar 1 substituent, R 2 is Ar 2 substituent, and R 3 is Ar 3 substituent. In another preferred embodiment, R 1 、R 2 or R 3 is a carbocyclic substituent, even more preferably an alicyclic or aromatic substituent, which is directly attached to the imide N or indirectly attached through a methylene chain ((-CH2) z ), where z = 1 to 6, and the methylene chain is the point of attachment to the imide N of the perylene substructure (W) or the naphthalene ring of compound (2), as described above. In yet another embodiment, R 1 、R 2 or R 3 substituents can independently be heterocyclic substituents, preferably N-containing heterocyclic substituents. For clarity, it is clear to those skilled in the art that R 1 and R 2 directly bonded to the diimide-N can not be heterocycles, especially N-containing heterocyclic substituents.

[0066] In a preferred embodiment, the Ar 1-3 substituent as described herein can have the structure (4) shown below, where R 4 、R 5 and R 6 are independently hydrogen, halogen, C1-C4 alkyl and its isomers, C1-C4 alkoxy, C1-C4 aminoalkyl or (fused) aromatic groups. The term "fused aromatic" encompasses compounds (4) of the fused aromatic-alicyclic substituent type and fused bicyclic or tricyclic compounds.

[0067]

[0068] R 1 、R 2 or R 3 Some specific examples of substituents are represented by the following formula, where *— represents the point of contact with the imide N of the perylene substructure (W) or the imide N of formula (2) or with the naphthalene moiety of formula (2) (i.e., R 3The direct contact points of (), as described herein, and X represents F, Br, Cl, OCH3, OPh. Although the substituent X is shown only in some of the formulas in the table below, those skilled in the art can also consider that the said substituent is present on other formulas described herein, as long as it is chemically possible. It should be noted that the formulas listed below do not cover an exhaustive list, but those skilled in the art can consider other chemically equivalent substituents.

[0069]

[0070]

[0071]

[0072] The UV-curable security ink composition described herein contains a UV free-radical curable compound. In a preferred embodiment, the UV-curable security printing ink composition contains one or more free-radical curable monomers, or one or more free-radical curable oligomers or mixtures thereof. Alternatively, in addition to the free-radical curable compounds described herein, the UV-curable security printing ink composition described herein may further contain one or more cationic curable compounds.

[0073] The UV free-radical curable composition contains one or more free-radical curable compounds, which are cured by a free-radical mechanism composed of the energy activation of at least one free-radical photoinitiator that releases free radicals, and the free radicals then initiate polymerization to form a binder. Preferably, the free-radical curable compounds are selected from (meth)acrylates, preferably selected from the group consisting of epoxy (meth)acrylate, (meth)acrylated oil, polyester and polyether (meth)acrylate, aliphatic or aromatic urethane (meth)acrylate, silicone (meth)acrylate, acrylic (meth)acrylate and mixtures thereof. In the context of the present invention, the term "(meth)acrylate" refers to acrylate and the corresponding methacrylate.

[0074] For embodiments where the UV curable security ink composition is a screen printing ink composition, flexographic printing ink composition or gravure printing ink composition, the composition preferably comprises one or more free radical curable oligomers, preferably in an amount of about 25 wt% to about 55 wt%; one or more free radical curable monomers selected from the group consisting of tri(meth)acrylates, tetra(meth)acrylates and mixtures thereof, preferably in an amount of about 10 wt% to about 50 wt%; and optionally one or more free radical curable monomers selected from the group consisting of mono(meth)acrylates, di(meth)acrylates and mixtures thereof, preferably in an amount of about 0 wt% to about 50 wt%, more preferably about 0 wt% to about 40 wt%, even more preferably about 0 wt% to about 30 wt%.

[0075] For embodiments where the UV curable security ink composition is a non-contact fluid microdispensing process printing ink composition, preferably an inkjet printing ink composition, more preferably a drop-on-demand (DOD) inkjet printing ink composition, the composition preferably comprises one or more free radical curable monomers selected from the group consisting of mono(meth)acrylates, di(meth)acrylates, tri(meth)acrylates, tetra(meth)acrylates and mixtures thereof, preferably in an amount of about 40 wt% to about 95 wt%, more preferably about 60 wt% to about 95 wt%, and may further comprise one or more free radical curable oligomers, preferably in an amount of about 0 wt% to about 35 wt%, more preferably about 0 wt% to about 20 wt%, by weight based on the total weight of the UV curable security ink composition.

[0076] As used herein, a free radical curable oligomer refers to a relatively high molecular weight oligomeric compound having a weight average molecular weight (MW) ≥ 400 g / mol, preferably ≥ 800 g / mol, more preferably ≥ 1000 g / mol. The free radical curable oligomers described herein are preferably (meth)acrylate oligomers, which may be branched or substantially linear, and one or more (meth)acrylate functional groups may be terminal and / or side groups bonded to the oligomer backbone, respectively. Preferably, the free radical curable oligomer is a (meth)acrylic oligomer, a urethane (meth)acrylate oligomer, a polyester (meth)acrylate oligomer, a polyether-based (meth)acrylate oligomer, an epoxy (meth)acrylate oligomer and mixtures thereof.

[0077] One or more of the mono(meth)acrylate monomers described herein are preferably selected from the group consisting of: alkyl (meth)acrylates, cycloalkyl (meth)acrylates, benzyl (meth)acrylates, phenyl (meth)acrylates (including phenoxyalkyl (meth)acrylates such as phenoxyethyl acrylate), cyclic trimethylolpropane formal acrylate, tetrahydrofurfuryl acrylate, aliphatic urethane (meth)acrylates, their alkoxylated (especially ethoxylated or propoxylated) compounds, and mixtures thereof.

[0078] Suitable di(meth)acrylate monomers include, but are not limited to, ethylene glycol diacrylate, ethylene glycol dimethacrylate; 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate; 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate; 2-methyl-1,3-propanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate; 2-butyl-2-ethyl-1,3-propanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate; neopentyl glycol diacrylate, neopentyl glycol dimethacrylate; 1,9-nonanediol diacrylate; 1,9-nonanediol dimethacrylate; 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, alkoxylated (especially ethoxylated and propoxylated) 1,6-hexanediol diacrylate; propoxylated neopentyl glycol diacrylate; ethoxylated 2-methyl-1,3-propanediol diacrylate; tricyclodecane dimethanol diacrylate); diethylene glycol diacrylate, diethylene glycol dimethacrylate; dipropylene glycol diacrylate; triethylene glycol diacrylate, triethylene glycol dimethacrylate; tripropylene glycol diacrylate; tripropylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate; polyethylene glycol 200 / 400 / 600 diacrylate, polyethylene glycol 200 / 400 / 600 dimethacrylate; ethoxylated (EO2 / EO3 / EO4 / EO10) bisphenol A diacrylate and ethoxylated (EO2 / EO3 / EO4 / EO10) bisphenol A dimethacrylate.

[0079] One or more of the (meth)acrylate monomers described herein are preferably selected from the group consisting of: trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, alkoxylated (especially ethoxylated or propoxylated) trimethylolpropane triacrylate, alkoxylated (especially ethoxylated or propoxylated) trimethylolpropane trimethacrylate, alkoxylated (especially ethoxylated or propoxylated) glycerol triacrylate, pentaerythritol triacrylate, alkoxylated (especially ethoxylated or propoxylated) pentaerythritol triacrylate, and mixtures thereof, preferably selected from the group consisting of: trimethylolpropane triacrylate, alkoxylated (especially ethoxylated or propoxylated) trimethylolpropane triacrylate, alkoxylated (especially ethoxylated or propoxylated) glycerol triacrylate, pentaerythritol triacrylate, and mixtures thereof.

[0080] One or more of the tetra(meth)acrylate monomers described herein are preferably selected from the group consisting of: ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, alkoxylated (such as, for example, ethoxylated and propoxylated) pentaerythritol tetra(meth)acrylate, and mixtures thereof, preferably selected from the group consisting of: ditrimethylolpropane tetra(meth)acrylate, alkoxylated pentaerythritol tetra(meth)acrylate, and mixtures thereof.

[0081] The UV curable security ink composition described herein may further comprise one or more (meth)acrylate-modified vinyl ethers (e.g., 2-(2-vinyloxyethoxy)ethyl acrylate (CAS No. 86273-46-3)).

[0082] Examples of free radical photoinitiators are known to those skilled in the art and are preferably selected from the group consisting of: aminoketone compounds (e.g., α-aminoketone compounds), hydroxyketone compounds (e.g., α-hydroxyketone compounds), alkoxyketone compounds (e.g., α-alkoxyketone compounds), acetophenone compounds, benzophenone compounds, ketosulfone compounds, benzyl ketal compounds, benzoin ether compounds, glyoxylate compounds, phosphine oxide compounds, and mixtures thereof, preferably selected from the group consisting of phosphine oxide compounds.

[0083] The UV curable security ink composition described herein comprises from about 0.1 to about 20% by weight of at least one of the free radical photoinitiators described herein, preferably from about 1 to about 15% by weight, based on the total weight of the UV curable security ink composition.

[0084] Suitable examples of α - aminoketone compounds include those containing a benzoyl moiety, also known as α - aminophenylethanone, such as 2 - methyl - 1 - [4 - (methylthio)phenyl] - 2 - morpholinopropan - 1 - one (CAS No. 71868 - 10 - 5); 2 - benzyl - 2 - dimethylamino - 1 - (4 - morpholinophenyl) - butan - 1 - one (CAS No. 119313 - 12 - 1); and 2 - dimethylamino - 2 - (4 - methylbenzyl) - 1 - (4 - morpholin - 4 - yl - phenyl) - butan - 1 - one (CAS No. 119344 - 86 - 4).

[0085] Suitable examples of α - hydroxyketones include, but are not limited to, 2 - hydroxy - 2 - methylpropiophenone (CAS No. 7473 - 98 - 5); 2 - hydroxy - 2 - methyl - 1 - (4 - tert - butyl)phenylpropan - 1 - one (CAS No. 68400 - 54 - 4); 2 - hydroxy - 4'-hydroxyethoxy - 2 - methylpropiophenone (CAS No. 106797 - 53 - 9); 2 - hydroxy - 1 - [4 - [4 - (1 - hydroxy - 2 - methylpropionyl)phenoxy]phenyl] - 2 - methylpropan - 1 - one (CAS No. 474510 - 57 - 1); (1 - hydroxycyclohexyl)phenylmethanone (CAS No. 947 - 19 - 3); 2 - hydroxy - 1 - [4 - [4 - (1 - hydroxy - 2 - methylpropionyl)phenoxy]phenyl] - 2 - methylpropan - 1 - one (CAS No. 71868 - 15 - 0); 1 - [2,3 - dihydro - 1 - [4 - (1 - hydroxy - 2 - methyl - 1 - oxopropyl)phenyl] - 1,3,3 - trimethyl - 1H - indene - 5 - yl] - 2 - hydroxy - 2 - methyl - 1 - propanone (CAS No. 135452 - 43 - 6); ar - (1 - hydroxy - 2 - methyl - 1 - oxopropyl)(1 - methylvinyl) - benzene homopolymer (CAS No. 163702 - 01 - 0,); α - (1,1 - dimethyl - 2 - oxo - 2 - phenylethyl) - ω - hydroxy - poly(oxy - 1,2 - ethanediyl) (9CI) (CAS No. 554449 - 21 - 7); polymeric α - hydroxy - ketone (CAS No. 1842314 - 75 - 3); or mixtures thereof.

[0086] Suitable examples of phenylethanone include, but are not limited to, 2,2 - diethoxyphenylethanone (CAS No. 6175 - 45 - 7); 2 - ethylhexyl 4 - dimethylaminobenzoate (CAS No. 21245 - 02 - 3); and 2 - methoxy - 2 - phenylphenylethanone (CAS No. 3524 - 62 - 7).

[0087] Suitable examples of benzophenone compounds include, but are not limited to, benzophenone (CAS No. 119-61-9); polymeric benzophenone derivatives; 2-methylbenzophenone (CAS No. 131-58-8); 3-methylbenzophenone (CAS No. 643-65-2); 4-methylbenzophenone (CAS No. 134-84-9); 2,4,6-trimethylbenzophenone (CAS No. 954-16-5); 3,3'-dimethyl-4-methoxybenzophenone (CAS No. 41295-28-7); 4-phenylbenzophenone (CAS No. 2128-93-0); 4-chlorobenzophenone (CAS No. 134-85-0); 4,4'-bis(diethylamino)benzophenone (CAS No. 90-93-7); methyl-2-benzoylbenzoate (CAS No. 606-28-0); 4-(4-methylphenylthio)benzophenone (CAS No. 83846-85-9); 4-hydroxybenzophenone laurate (CAS No. 142857-24-7), and a mixture of 50% benzophenone (CAS 119-61-9) and 50% 1-hydroxycyclohexyl phenyl ketone (CAS No. 947-19-3).

[0088] Suitable examples of ketone sulfone compounds include, but are not limited to, 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one (CAS No. 272460-97-6).

[0089] Suitable examples of benzyl ketal compounds are not limited to 2,2-dimethoxy-2-phenylacetophenone (CAS No. 24650-42-8).

[0090] Suitable examples of benzoin ethers include, but are not limited to, 2-ethoxy-1,2-diphenylethanone (CAS No. 574-09-4); 2-isopropoxy-1,2-diphenylethanone (CAS No. 6652-28-4); 2-isobutoxy-1,2-diphenylethanone (CAS No. 22499-12-3); 2-butoxy-1,2-diphenylethanone (CAS No. 22499-11-2); 2,2-dimethoxy-1,2-diphenylethanone (CAS No. 24650-42-8); and 2,2-diethoxyacetophenone (CAS No. 6175-45-7).

[0091] Suitable examples of glyoxylate compounds include, but are not limited to, methyl 2-oxo-2-phenylacetate (CAS No. 15206-55-0); 2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl 2-oxo-2-phenylacetate (CAS No. 211510-16-6); 2-[2-hydroxy-ethoxy]-ethyl 2-oxo-phenyl-acetate (CAS No. 442536-99-4); α-(1-oxo-2-phenylacetyl)-ω-[(1-oxo-2-phenylacetyl)oxy]-poly(oxy-1,4-butanediyl) (CAS No. 1313205-82-1); and mixtures thereof; more preferably methyl 2-oxo-2-phenylacetate (CAS No. 15206-55-0); 2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl 2-oxo-2-phenylacetate (CAS No. 211510-16-6); or mixtures thereof.

[0092] Suitable examples of phosphine oxide compounds include, but are not limited to, (1,4,6-trimethylbenzoyl)diphenylphosphine oxide (CAS No. 75980-60-8); 2,4,6-trimethylbenzoyl-ethoxyphenylphosphine oxide (CAS No. 84434-11-7); phenyl-bis(2,4,6-trimethylbenzoyl)phosphine oxide (CAS No. 162881-26-7); bis(1,6-dimethoxybenzoyl)(1,4,4-trimethylpentyl)phosphine oxide (CAS No. 145052-34-2); ethyl(3-benzoyl-2,4,6-trimethylbenzoyl)(phenyl)phosphinate (CAS No. 1539267-56-5); α,α’,α”-1,2,3-propanetriyltris[ω-[[phenyl(1,4,6-trimethylbenzoyl)phosphinyloxy]oxy]-poly(oxy-1,2-ethanediyl) (CAS 1834525-17-5); or mixtures thereof, such as, for example, a mixture of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (CAS No. 75980-60-8) and 2-hydroxy-2-methylpropiophenone (CAS No. 7473-98-5), a mixture of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (CAS No. 162881-26-7) and 2-hydroxy-2-methylpropiophenone (CAS No. 7473-98-5); and a mixture of ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate (CAS No. 84434-11-7) and 2-hydroxy-2-methylpropiophenone (CAS No. 7473-98-5).

[0093] For embodiments in which the UV-curable safety ink composition comprises more than one cationically curable compound, the ink composition comprises a cationic photoinitiator.

[0094] Examples of various available photoinitiators can be found in standard textbooks such as "Chemistry & Technology of UV & EB Formulation for Coatings, Inks & Paints", Volume III, "Photoinitiators for Free Radical Cationic and Anionic Polymerization", 2nd Edition, J.V. Crivello & K. Dietliker, edited by G. Bradley and published in 1998 by John Wiley & Sons in association with SITA Technology Limited.

[0095] For effective curing, it may also be advantageously included at least one photosensitizer and more than one photoinitiator, wherein the sensitizer is preferably a thioxanthone compound. Suitable examples of sensitizers include, but are not limited to, 2-methylthioxanthone (CAS No. 15774-82-0); 2-isopropyl-9H-thioxanthen-9-one (CAS No. 5495-84-1); 4-(1-methylethyl)-9H-thioxanthen-9-one (CAS No. 83846-86-0); 2,4-diethyl-9H-thioxanthen-9-one (CAS No. 82799-44-8); 2-chloro-9H-thioxanthen-9-one (CAS No. 86-39-5); 1-chloro-4-propoxy-9H-thioxanthen-9-one (CAS No. 142770-42-1); 1,3-bis[[α-[(1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetyl]poly[oxy(1-methylethylene)]]oxy]-2,2-bis[[α-[(1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetyl]poly[oxy(1-methylethylene)]]oxymethylpropane (CAS No. 1003567-83-6); α-[2-[(9-oxothioxanthenyl)oxy]acetyl]-ω-[[2-[(9-oxothioxanthenyl)oxy]acetyl]oxy]-poly(oxy-1,4-butylene) (CAS No. 813452-37-8); 2-[2-[1-[2-[[2-(9-oxothioxanthen-2-yl)oxyacetyl]amino]-3-[1-[2-(2-propenoyloxyethoxy)ethoxy]-2-[1-[2-(2-propenoyloxyethoxy)ethoxy]methyl]propoxy]ethoxy]ethoxy]ethyl prop-2-enoate (CAS No. 1427388-03-1); α-[2-[(9-oxo-9H-thioxanthenyl)oxy]acetyl]-ω-[[2-[(9-oxo-9H-thioxanthenyl)oxy]acetyl]oxy]-poly(oxy-1,4-butylene) (CAS No. 813452-37-8); its oligomeric and polymeric compounds (CAS Nos. 515139-51-2 and 2055335-46-9); and mixtures thereof.

[0096] When present, the at least one photosensitizer is preferably present in an amount of from about 0.1 wt% to about 2 wt%, more preferably from about 0.2 wt% to about 1 wt%, based on the total weight of the UV curable security ink composition.

[0097] The UV-curable security ink composition described herein may further comprise one or more co-sensitizers, which include aliphatic or aromatic tertiary amines, wherein the amine may be triethylamine, N,N-dimethylethanolamine, N-methyl-diethanolamine, triethanolamine, 2-(dimethylamino)ethyl benzoate, ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-dimethylaminobenzoate, isopentyl-4-dimethylaminobenzoate, butoxyethyl-4-dimethylaminobenzoate, amino-modified acrylate resin or oligoaminobenzoate.

[0098] The UV-curable security ink composition described herein may further comprise one or more cationic curable compounds and one or more cationic photoinitiators. The cationic curable compounds cure by a cationic mechanism, which generally involves activating one or more compounds by radiation, and the one or more compounds release cationic species such as acids, and the cationic species in turn initiate curing to cause monomers and / or oligomers to react and / or crosslink to harden the coating composition. Preferably, the one or more cationic curable compounds are selected from the group consisting of vinyl ethers, allyl ethers, cyclic ethers such as epoxides, oxetanes, glycidyl ethers and tetrahydrofuran, lactones, cyclic thioethers, vinyl sulfides, allyl sulfides, hydroxy-containing compounds and mixtures thereof, preferably the cationic curable compounds are selected from the group consisting of vinyl ethers, allyl ethers, cyclic ethers such as epoxides, oxetanes and tetrahydrofuran, lactones and mixtures thereof, more preferably the cationic curable compounds are selected from the group consisting of vinyl ethers, cyclic ethers such as epoxides, oxetanes and tetrahydrofuran and mixtures thereof. Typical examples of cationic photoinitiators include iodonium salts, especially diaryliodonium salts, oxonium salts, especially triaryloxonium salts, sulfonium salts, especially diarylsulfonium salts and mixtures thereof.

[0099] The UV-curable security ink composition described herein may further comprise at least one colorant, such as a pigment or a dye. For the purposes of the present invention, a pigment is a colorant that is insoluble or slightly soluble in the ink composition, while a dye is completely soluble in the ink composition. Preferably, the at least one colorant is an IR-transparent organic pigment or an IR-transparent organic dye. The pigments or dyes preferably included are transparent in the IR region, especially in the near-IR region, as this allows for the further introduction of specific IR absorbers into the ink composition for the purpose of enhancing the anti-counterfeiting properties of the security features.

[0100] Suitable organic pigments include, but are not limited to, C.I. Pigment Yellow 12, C.I. Pigment Yellow 24, C.I. Pigment Yellow 42, C.I. Pigment Yellow 93, C.I. Pigment 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 138, C.I. Pigment Yellow 139, C.I. Pigment Yellow 147, C.I. Pigment Yellow 150, C.I. Pigment Yellow 155, C.I. Pigment Yellow 173, C.I. Pigment Yellow 185; C.I. Pigment Orange 34, C.I. Pigment Orange 48, C.I. Pigment Orange 49, C.I. Pigment Orange 61, C.I. Pigment Orange 71, C.I. Pigment Orange 73; C.I. Pigment Orange 77; C.I. Pigment Red 9, C.I. Pigment Red 22, C.I. Pigment Red 23, C.I. Pigment Red 67, C.I. Pigment Red 122, C.I. Pigment Red 144, C.I. Pigment Red 146, C.I. Pigment Red 168, C.I. Pigment Red 170, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 179, C.I. Pigment Red 185, C.I. Pigment Red 189, C.I. Pigment Red 190, C.I. Pigment Red 194, C.I. Pigment Red 195, C.I. Pigment Red 196, C.I. Pigment Red 202, C.I. Pigment Red 224, C.I. Pigment Red 242, C.I. Pigment Red 254, C.I. Pigment Red 255, C.I. Pigment Red 264; C.I. Pigment Brown 23, C.I. Pigment Brown 25, C.I. Pigment Brown 30, C.I. Pigment Blue 15, C.I. Pigment Blue 15:3, C.I. Pigment Blue 22, C.I. Pigment Blue 60, C.I. Pigment Blue 64, C.I. Pigment Blue 65, C.I. Pigment Violet 19, C.I. Pigment Violet 23, C.I. Pigment Violet 31, C.I. Pigment Violet 32, C.I. Pigment Violet 33, C.I. Pigment Violet 37, C.I. Pigment Green 7, C.I. Pigment Green 36, C.I. Pigment Green 47, C.I. Pigment Green 54, C.I. Pigment Black 31, C.I. Pigment Black 32, C.I. Pigment White 4, C.I. Pigment White 6, C.I. Pigment White 21 and C.I. Pigment White 22 or mixtures thereof.

[0101] Suitable organic dyes include, but are not limited to, C.I. Solvent Yellow 19, C.I. Solvent Yellow 79, C.I. Solvent Yellow 81, C.I. Solvent Yellow 82, C.I. Solvent Yellow 88, C.I. Solvent Orange 45, C.I. Solvent Orange 54, C.I. Solvent Orange 56, C.I. Solvent Orange 99, C.I. Solvent Red 8, C.I. Solvent Red 119, C.I. Solvent Red 122, C.I. Solvent Red 127, C.I. Solvent Red 130, C.I. Solvent Red 160, C.I. Solvent Red 233, C.I. Solvent Green 7, C.I. Solvent Blue 67, C.I. Solvent Blue 70, C.I. Solvent Brown 27, C.I. Solvent Brown 43, C.I. Solvent Brown 44, C.I. Solvent Black 27, C.I. Solvent Black 28, and C.I. Solvent Black 29, or mixtures thereof.

[0102] For embodiments in which the UV-curable security ink composition described herein lacks the at least one colorant (i.e., the composition contains about 0 wt% of the at least one colorant), the UV-curable security ink composition preferably contains the at least one compound P described herein in a total amount of from about 0.005 wt% to about 0.2 wt%, based on the total weight of the UV-curable security ink composition.

[0103] For embodiments in which the UV-curable security ink composition described herein contains the at least one colorant in an amount of from about 0.1 wt% to about 20 wt%, preferably from about 0.5 wt% to about 10 wt%, the UV-curable security ink composition preferably contains the at least one compound P described herein in a total amount of from about 0.1 wt% to about 1.0 wt%, based on the total weight of the UV-curable security ink composition.

[0104] The UV-curable security ink composition described herein may further comprise at least one additive, the at least one additive including, but not limited to, compounds and materials for adjusting physical, rheological, and chemical parameters of the composition such as viscosity, consistency, UV stability, adhesion properties, antistatic properties, storage stability, and the like. The additives described herein may be present in the coating composition in amounts and forms known in the art, including so-called nanomaterials, wherein at least one dimension of the additive is in the range of 1 to 1000 nm. The one or more additives are preferably miscible or dispersible with the UV-curable security ink composition, i.e., they do not phase-separate from the remainder of the composition during shelf-life.

[0105] Examples of additives include surfactants, where the surfactant can be a fluorosurfactant, siloxane, silicone, silanol, polyoxyalkyleneamine, propoxylated (poly(oxypropylene)) diamine, alkyl etheramine, nonylphenol ethoxylate, ethoxylated fatty amine, quaternized copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate, diethanolamine salt of a fluorinated organic acid, alkoxylated ethylenediamine, polyethylene oxide, polyoxyalkylene polyalkylene polyamineamine, polyoxyalkylene polyalkylene polyimine, a mixture of alkyl phosphate ethoxylates, polyoxyalkylene derivatives of propylene glycol, polyoxyethylated fatty alcohols, or mixtures thereof. The surfactant additive can be present in an amount of from about 0.01 wt% to about 1.0 wt%, by weight percentage based on the total weight of the UV curable security ink composition.

[0106] The UV curable security ink composition described herein does not contain evaporable components such as organic solvents. However, it may be advantageous to sometimes incorporate small amounts of more than one organic solvent to improve adhesion to the substrate surface after UV curing. In such cases, the more than one organic solvent added can be in any amount within a range that does not cause solvent resistance and VOC problems, and is preferably in an amount of from about 0.1 wt% to about 5.0 wt%, by weight percentage based on the total weight of the UV curable security ink composition.

[0107] The UV curable security ink composition described herein is particularly suitable for being applied to substrates such as those described herein by a printing process preferably selected from the group consisting of screen printing processes, rotogravure processes, flexographic processes, and non-contact fluid microdispensing processes, more preferably a non-contact fluid microdispensing process.

[0108] Screen printing (also known in the art as silkscreen printing) is a stencil process whereby ink is transferred through a stencil to a surface, the stencil being supported by a fine fabric mesh of silk, synthetic fiber or wire stretched on a frame. The holes in the mesh are blocked in the non-image areas and remain open in the image areas, and the image carrier is called a screen. Screen printing can be flat printing or rotary printing. During printing, ink is supplied to the frame, the ink accumulates above the screen, and then a squeegee is drawn across the screen, forcing the ink through the open holes in the screen. At the same time, the surface to be printed is kept in contact with the screen, and the ink is transferred to the surface to be printed. Screen printing is further described, for example, in: The Printing Ink Manual, R.H. Leach and R.J. Pierce, Springer Edition, 5th Edition, pages 58-62, and Printing Technology, J.M. Adams and P.A.Dolin, Delmar Thomson Learning, 5th Edition, pages 293-328.

[0109] As is known to those skilled in the art, the term "rotogravure" refers to a printing process described, for example, in "Handbook of Print Media", Helmut Kipphan, Springer Edition, page 48. Rotogravure is a printing process in which the image elements are engraved in the surface of a cylinder. The non-image areas are at a constant original level. Before printing, the entire printing plate (non-printing and printing elements) is inked and flooded with ink. Before printing, the ink is removed from the non-image areas by a wiper or doctor blade so that the ink remains only in the cells. The image is transferred from the cells to the substrate by pressure, typically in the range of 2-4 bar, and by the adhesion force between the substrate and the ink. The term "rotogravure" does not include intaglio printing processes (also known in the art as engraving or copperplate printing processes), which rely on, for example, different types of ink.

[0110] Flexographic printing methods preferably use a unit having a chamber doctor blade, an anilox roll, and a printing plate cylinder. The anilox roll advantageously has small cells, the volume and / or density of which determines the application rate of the protective varnish. The chamber doctor blade bears against the anilox roll, filling the cells while scraping off the excess protective varnish. The anilox roll transfers the ink to the printing plate cylinder, which ultimately transfers the ink to the substrate. The printing plate cylinder can be made of a polymeric or elastomeric material. Polymers are mainly used as photopolymers in the printing plate and sometimes as a seamless coating on the sleeve. A photopolymer printing plate is made of a photosensitive polymer that is hardened by ultraviolet (UV) light. The photopolymer printing plate is cut to the desired size and placed in a UV exposure unit. One side of the plate is fully exposed to UV light to harden or cure the base of the plate. The plate is then flipped, the negative of the job is mounted on the uncured side, and the plate is further exposed to UV light. This hardens the plate in the image areas. The plate is then processed to remove the unhardened photopolymer from the non-image areas, which reduces the surface of the plate in these non-image areas. After processing, the plate is dried and given a post-exposure dose of UV light to cure the entire plate. The preparation of a printing plate cylinder for flexographic printing is described in: Printing Technology, J.M. Adams and P.A. Dolin, Delmar Thomson Learning, 5th Edition, pages 359-360.

[0111] Depending on the printing process selected for producing the security features described herein, viscosity values of suitable UV-curable security ink compositions are used: screen printing inks have viscosities between about 50 mPa·s and about 3000 mPa·s at 25 °C, flexographic inks have viscosities between about 50 mPa·s and about 2000 mPa·s at 25 °C, and gravure inks have viscosities between about 50 mPa·s and about 1000 mPa·s at 25 °C, wherein the viscosity measurements of security inks having viscosity values between 100 mPa·s and 3000 mPa·s are carried out with a Brookfield viscometer (model "RVDV-I Prime"), and the spindle and rotational speed (rpm) are adjusted according to the following viscosity ranges: for viscosity values between 100 and 500 mPa·s, spindle 21 at 100 rpm; for viscosity values between 500 mPa·s and 2500 mPa·s, spindle 27 at 100 rpm; and for viscosity values between 2500 mPa·s and 3000 mPa·s, spindle 27 at 50 rpm, and wherein the viscosity measurements of security inks having viscosity values between 10 mPa·s and 100 mPa·s are carried out with a rotational viscometer DHR-2 from TA Instruments having a cone and plate geometry and a diameter of 40 mm at 25 °C and 1000 s -1Next, it is carried out at 0.3 - 60 rpm and a temperature of 45 °C using a DIN 4" cup or a Brookfield DV1 LV viscometer equipped with a spindle LV1.

[0112] The non-contact fluid microdispensing process described herein is preferably selected from the group consisting of spraying, aerosol jet printing, electrohydrodynamic printing, slot die coating, and inkjet printing, more preferably by an inkjet printing process, wherein the non-contact fluid microdispensing printing process is a variable information printing method that allows for the unique production of the security features described herein. The application process is selected based on the design and resolution of the security feature to be produced.

[0113] Spraying is a technique that involves forcing a composition through a nozzle to form a fine aerosol. It can involve a carrier gas and electrostatic charging to assist in directing the aerosol to the surface to be printed. Spraying printing allows for the printing of dots and lines. Suitable compositions for spraying printing typically have a viscosity between about 10 mPa·s and about 1 Pa·s (25 °C, 1000 s -1 ). The resolution of spraying printing is in the millimeter range. Spraying printing is described, for example, in: F.C. Krebs, Solar Energy Materials & Solar Cells (2009), 93, page 407.

[0114] Aerosol jet printing (AJP) is an emerging non-contact direct writing method aimed at producing fine features on a wide range of substrates. AJP is compatible with a wide range of materials and free-form deposition, allowing for high resolution (on the order of about 10 microns) as well as relatively large spacing distances (e.g., 1 - 5 mm), in addition to independence from orientation. This technique involves using an ultrasonic or pneumatic nebulizer to generate an aerosol from a composition that typically has a viscosity between about 1 mPa·s and about 1 Pa·s (25 °C, 1000 s -1 ). Aerosol jet printing is described, for example, in: N.J. Wilkinson et al., The International Journal of Advanced Manufacturing Technology (2019) 105: 4599 - 4619.

[0115] Electrohydrodynamic inkjet printing is a high-resolution inkjet printing technology. Electrohydrodynamic inkjet printing technology utilizes an externally applied electric field to manipulate droplet size, ejection frequency, and placement on a substrate to achieve higher resolution than traditional inkjet printing while maintaining high production speeds. The resolution of electrohydrodynamic inkjet printing is approximately two orders of magnitude higher than that of traditional inkjet printing technology; thus, it can be used for the orientation of nano- and micro-scale patterns. Electrohydrodynamic inkjet printing can be used in both DOD and continuous modes. Compositions for electrohydrodynamic inkjet printing typically have viscosities between about 1 mPa·s and about 1 Pa·s (25 °C, 1000 s -1 ). The electrohydrodynamic inkjet printing technology is described, for example, in: P.V. Raje and N.C. Murmu, International Journal of Emerging Technology and Advanced Engineering, (2014), 4(5), pages 174 - 183.

[0116] Slot die coating is a one-dimensional coating technology. Slot die coating allows for the coating of material strips, which is well-suited for the manufacture of multi-layer coatings having different material strips laminated on top of each other. Alignment of the pattern is generated by translating the coating head in a direction perpendicular to the web travel direction. The slot die coating head includes a mask that defines a slot of the coating head through which the slot die coating ink is dispersed. Examples of slot die coating heads are illustrated in: F.C. Krebs, Solar Energy Materials & Solar Cells (2009), 93, pages 405 - 406. Suitable compositions for slot die coating typically have viscosities between about 1 mPa·s and about 20 mPa·s (25 °C, 1000 s -1 ).

[0117] According to one embodiment, the UV curable security ink composition described herein is printed by an inkjet printing process, preferably a continuous inkjet (CI) printing process or a drop-on-demand (DOD) inkjet printing process, more preferably a drop-on-demand (DOD) inkjet printing process. Drop-on-demand (DOD) printing is a non-contact printing process in which droplets are generated only when printing is required and are typically generated by a jetting mechanism rather than by destabilizing a jet. Depending on the mechanism used to cause the print head to generate droplets, DOD printing is divided into piezoelectric pulse, thermal jet, valve jet (viscosity between about 1 mPa·s and about 1 Pa·s (25 °C, 1000 s -1 )) and electrostatic processes. Generally, the viscosities of DOD inkjet printing ink compositions suitable for piezoelectric and thermal DOD inkjet printing are below 30 mPa·s at 25 °C.

[0118] The viscosity of the UV-curable security ink composition described herein can be adjusted by changing the ratio between one or more radical-curable monomers and / or one or more radical-curable oligomers described herein.

[0119] The security feature described herein is prepared by a method comprising the steps of: a) applying, preferably printing, the UV-curable security ink composition described herein, and b) at least partially curing the UV-curable security ink composition from step a).

[0120] The UV-curable security ink composition described herein is particularly suitable for being applied to substrates such as those described herein by the following printing processes, which are preferably selected from the group consisting of pad printing processes, screen printing processes, rotogravure processes, flexographic processes, and non-contact fluid microdispensing processes, more preferably the non-contact fluid microdispensing process as described herein, still more preferably the inkjet printing process.

[0121] The method described herein includes step b) of at least partially curing the UV-curable security ink composition from step a), wherein the curing step is carried out with a curing unit. Suitable curing units include equipment for UV curing units that contain light-emitting diodes (LED) lamps or arc discharge lamps as actinic radiation sources, such as medium-pressure mercury arc (MPMA) or metal vapor arc lamps. According to one embodiment, the curing unit is a UV-Vis light-emitting diode (LED) curing unit. Contrary to medium-pressure mercury lamps that have emission bands in the UV-A, UV-B, and UV-C regions of the electromagnetic spectrum, UV-LED lamps emit radiation in the UV-A region, for example, in the range of about 380 nm to about 410 nm. In addition, current UV-LED lamps emit quasi-monochromatic radiation, i.e., they emit only at one wavelength, such as 365 nm, 385 nm, 395 nm, or 405 nm.

[0122] According to one embodiment, step b) of at least partially curing the UV-curable security ink composition described herein consists of: exposing the composition to one or more wavelengths between about 360 nm and about 410 nm emitted by one or more UV-LED curing units in order to form a security feature. Preferably, step b) described herein consists of: exposing the UV-curable security ink composition to a single wavelength between 365 nm and 420 nm, such as, for example, 365 nm, 385 nm, 395 nm, or 405 nm, emitted by a UV-LED source in order to form a security feature. The UV-curable security ink composition is preferably exposed to the following dose of UV light: at least 150 mJ / cm 2 of the dose, more preferably 200 mJ / cm 2The above dosage is used to cure the UV-curable security ink composition and form security features, where the dosage can be measured using a UVPower II radiometer from EIT, Inc., U.S.A. II radiometer measurement.

[0123] The present invention further provides security features obtained by the method for manufacturing security features described herein. The present invention further provides security features made of the UV-Vis curable security ink described herein, preferably UV-Vis curable continuous inkjet (CI) or drop-on-demand (DOD) inkjet printed security ink, on the substrate described herein.

[0124] According to one embodiment, the security features described herein are composed of more than one indicia. As used herein, the term "indicia" shall mean continuous and discontinuous layers composed of distinguishing marks or signs or patterns. Preferably, the more than one indicia described herein are selected from the group consisting of: codes, symbols, alphanumeric symbols, motifs, geometric patterns (such as circles, triangles, and regular or irregular polygons), letters, words, numbers, logos, pictures, portraits, and combinations thereof. Examples of codes include coded marks such as coded alphanumeric data, one-dimensional barcodes, two-dimensional barcodes, QR codes, data matrices, and IR-readable codes. The more than one indicia (x30) described herein can be solid indicia and / or raster indicia.

[0125] The substrates for the security features described herein are preferably selected from the group consisting of: paper or other fibrous materials such as cellulose (including woven and non-woven fibrous materials), paper-containing materials, glass, metal, ceramic, plastic and polymer, metallized plastic or polymer, composite materials, and mixtures or combinations of two or more thereof. Typical papers, paper-like or other fibrous materials are made of various fibers, including but not limited to, abaca, cotton, linen, wood pulp, and their blends. As is well known to those skilled in the art, cotton and cotton / linen blends are preferably used for banknotes, while wood pulp is usually used for non-banknote security documents. Typical examples of plastics and polymers include: polyolefins such as polyethylene (PE) and polypropylene (PP) including biaxially oriented polypropylene (BOPP), polyamides, polyesters such as poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(ethylene 2,6-naphthalate) (PEN), and polyvinyl chloride (PVC). As in the trademark The spunbond olefin fibers sold below can also be used as the substrate. Typical examples of metallized plastics or polymers include the above-mentioned plastic or polymer materials on which metals are deposited continuously or discontinuously on their surfaces. Typical examples of metals include, but are not limited to, aluminum (Al), chromium (Cr), copper (Cu), gold (Au), silver (Ag), their alloys, and combinations of two or more of the above metals. The metallization of the above plastic or polymer materials can be accomplished by an electrodeposition process, a high-vacuum coating process, or by a sputtering process. Typical examples of composite materials include, but are not limited to: multi-layer structures or laminates of paper and at least one plastic or polymer material such as those described above, and plastics and / or polymer fibers introduced into paper-like or fibrous materials such as those described above. Of course, the substrate can further contain additives known to those skilled in the art, such as fillers, sizing agents, brightening agents, processing aids, reinforcing or humidifying agents, etc.

[0126] The present invention further provides a security document comprising the substrate described herein and the security feature described herein or a security document comprising more than one security feature described herein. Security documents include, but are not limited to, valuable documents and valuable goods. Typical examples of valuable documents include, but are not limited to, banknotes, deeds, bills, checks, vouchers, stamps, tax labels, and agreements, etc., identity documents such as passports, identity cards, visas, driver's licenses, bank cards, credit cards, transactions cards, access documents or cards, admission tickets, and public transport tickets or titles, etc. The term "valuable goods" refers to packaging materials, especially those used in the pharmaceutical, cosmetic, electronic, or food industries, which can be protected against forgery and / or illegal reproduction in order to guarantee the contents of the package, such as genuine drugs. Examples of these packaging materials include, but are not limited to, labels, such as certified brand labels, tamper evidence labels, and seals. Preferably, the security document described herein is selected from the group consisting of: banknotes, identity documents, authorization documents, driver's licenses, credit cards, access cards, transport titles, vouchers, and security product labels. Alternatively, the security feature described herein can be produced on an auxiliary substrate, such as a security thread, security strip, foil, decal, window, or label, and thus transferred to the security document in a separate step.

[0127] For the purpose of further enhancing the security level of security documents and the resistance to forgery and illegal reproduction, the substrates described herein may include printed, coated, laser - marked or laser - perforated markings, watermarks, security threads, fibers, planchettes, luminescent compounds, windows, foils, labels, primers, and combinations of two or more thereof.

[0128] For the purpose of increasing durability by stain - resistance or chemical - resistance and cleanliness, and thereby increasing the cycle life of security documents, or for the purpose of changing their aesthetic appearance (such as optical gloss), one or more protective layers may be applied over the security features or security documents described herein. When present, one or more protective layers are typically made of a protective varnish, which may be transparent, slightly colored or colored, and may be somewhat glossy. The protective varnish may be a radiation - curable composition, a heat - drying composition, or any combination thereof. Preferably, one or more protective layers are made of a radiation - curable composition, more preferably a UV - Vis curable composition.

[0129] The security features described herein may be directly provided on the substrate, and the security features will be permanently retained on the substrate (such as for banknote applications). Alternatively, the security features may also be provided on a temporary substrate for production purposes, and then the security features are removed from the temporary substrate. Thereafter, after the UV - Vis radiation - radical - curable security ink, preferably the UV - Vis radiation - radical - curable screen - printing security ink, used to produce the security features described herein has hardened / cured, the temporary substrate can be removed from the security features.

[0130] Alternatively, in another embodiment, an adhesive layer may be present on the security feature or on the substrate containing the security feature, on the side of the substrate opposite to the side on which the security feature is provided, or on the same side as the security feature and on top of the security feature. Thus, the adhesive layer may be applied to the security feature or to the substrate, and the adhesive layer is applied after the curing step has been completed. Such articles can be attached to all kinds of documents or other articles or items without printing or other processes involving machinery and a rather high workload. Alternatively, the substrate containing the security features described herein may be in the form of a transfer foil, which can be applied to a document or an item in a separate transfer step. For this purpose, the substrate is provided with a release coating, and as described herein, the security features are produced on the release coating. One or more adhesive layers may be applied over the security features thus produced.

[0131] The present document also describes substrates, security documents, decorative elements and objects comprising more than one, i.e., two, three, four, etc. of the security features described herein. The present document also describes articles comprising the security features described herein, in particular security documents, decorative elements or objects.

[0132] As mentioned above, the security features described herein can be used to protect and authenticate security documents or decorative elements.

[0133] Typical examples of decorative elements or objects include, but are not limited to, luxury goods, cosmetic packaging, vehicle parts, electronic / electrical appliances, furniture and nail art items.

[0134] Security documents include, but are not limited to, valuable documents and valuable goods. Typical examples of valuable documents include, but are not limited to, banknotes, deeds, bills, cheques, vouchers, stamps and tax labels, and agreements, etc., identity documents such as passports, identity cards, visas, driving licences, bank cards, credit cards, transaction cards, access documents or cards, tickets of admission, public transport tickets, and academic diplomas or title deeds, etc., preferably banknotes, identity documents, authorisation documents, driving licences and credit cards. The term "valuable goods" refers to packaging materials, in particular for cosmetics, nutritional products, pharmaceuticals, alcohol, tobacco products, beverages or foodstuffs, electronic / electrical products, fabrics or jewellery, i.e., articles that should be protected against forgery and / or illegal reproduction to guarantee the contents of the packaging, such as genuine pharmaceuticals. Examples of such packaging materials include, but are not limited to, labels, such as certified brand labels, tamper-evident labels and seals. It should be noted that the disclosed substrates, valuable documents and valuable goods are given only by way of example and do not limit the scope of the present invention.

[0135] Without departing from the spirit of the present invention, those skilled in the art can envisage several modifications to the above specific embodiments. These modifications are included in the present invention.

[0136] Furthermore, all documents mentioned throughout the present specification are incorporated herein by reference in their entirety, as fully set forth herein.

[0137] Examples

[0138] The present invention will now be described in more detail with reference to non-limiting examples. The following examples provide more details on the preparation of the UV-curable security ink compositions described herein and the fluorescence intensity and lightfastness of the machine-readable security features made therefrom.

[0139] The UV-curable security ink compositions E1-E3 and C1-C6 are inks without any colourants, while the UV-curable security ink compositions E4-E6 and C7-C12 are inks with colourants.

[0140] Preparation of Compounds Mo, Mo', and M1 - M9

[0141]

[0142] To a mixture of 5,12 - dibromoanthra[2,1,9 - def:6,5,10 - d'e'f']diisoquinoline - 1,3,8,10 - tetrone (3.80 g, 6.91 mmol, purity 95% and containing a mixture of 5,12 - dibromo (Mo), 5 - 13 - dibromo (Mo') isomers and 5,12,13 - tribromo isomer (not shown)) (CAS No. 118129 - 60 - 5, from abcr GmbH) in propionic acid (6.65 g, 6.72 ml) was added 2,6 - diisopropylaniline (3.67 g, 20.7 mmol). The reaction mixture was stirred at 140 °C for 18 h. Then it was cooled to room temperature, poured into 20 mL of 2 M HCl, stirred for 30 min, and then filtered. The crude red solid was purified by MPLC chromatography on a Puriflash system (cyclohexane - dichloromethane 4:1) to give 2 g (42% yield) of 5,12 - dibromo - 2,9 - bis(2,6 - diisopropylphenyl)anthra[2,1,9 - def:6,5,10 - d'e'f']diisoquinoline - 1,3,8,10(2H,9H) - tetrone (CAS: 331861 - 94 - 0) as the main product (M1) and 5,13 - dibromo - 2,9 - bis(2,6 - diisopropylphenyl)anthra[2,1,9 - def:6,5,10 - d'e'f']diisoquinoline - 1,3,8,10(2H,9H) - tetrone (CAS: 861853 - 33 - 5) as the minor product (M1'). Purification of the diimide product by chromatography allowed removal of the 5,12,13 - tribromo isomer. The 1 1H NMR (400 MHz, CDCl3) δ 9.59 (d, J = 8.1 Hz, 2H), 9.05 (s, 2H), 8.83 (d, J = 8.1 Hz, 2H), 7.54 (t, J = 7.8 Hz, 2H), 7.39 (d, J = 7.8 Hz, 4H), 2.76 (sept, J = 6.9 Hz, 4H), 1.22 (d, J = 6.9, 24H). For M1' 1 1H NMR (400 MHz, CDCl3) δ 9.60 (d, J = 8.1, 2H), 9.05 (s, 2H), 8.84 (d, J = 8.1 Hz, 2H), 7.54 (t, J = 7.8 Hz, 2H), 7.39 (d, J = 7.8 Hz, 4H), 2.76 (sept, J = 6.9 Hz, 4H), 1.22 (d, J = 6.9, 24H). It has been through 1The ratio between the 5,12-dibromo (M1) and 5,13-dibromo (M1’) isomers was determined by ¹H-NMR to be 3:1, 75% (M1) and 25% (M1’). This mixture was used for the synthesis of all derivatives without separation. For simplicity, only the major isomer is mentioned in the following syntheses.

[0143]

[0144] To a solution of M1 (2.0 g, 2.30 mmol) in dimethyl sulfoxide (33 ml) was added 4-methoxyphenol (1.72 g, 13.8 mmol) and K₂CO₃ (1.91 g, 13.8 mmol), and the reaction mixture was stirred at 115 °C for 90 min. The reaction mixture was then poured into 2 M HCl, and the purple precipitate was filtered off. The crude product was dissolved in dichloromethane and extracted twice with 1 M NaOH. The combined organic phases were dried over magnesium sulfate, filtered, and concentrated to give 2,9-bis(2,6-diisopropylphenyl)-5,12-bis(4-methoxyphenoxy)anthra[2,1,9-def:6,5,10-d’e’f’]diisoquinoline-1,3,8,10(2H,9H)-tetrone (M2) as a red solid (2.10 g, 96%). 1 ¹H NMR (400 MHz, CDCl₃) δ 9.71 (d, J = 8.4 Hz, 2H), 8.73 (d, J = 8.4 Hz, 2H), 8.41 (s, 2H), 7.49 (t, J = 7.8 Hz, 2H), 7.34 (d, J = 7.8 Hz, 4H), 7.20 – 7.13 (m, 4H), 7.05 – 6.98 (m, 4H), 3.87 (s, 6H), 2.74 (sept, J = 6.8 Hz, 4H), 1.22 – 1.13 (m, 24H).

[0145]

[0146] Under nitrogen at 20 °C, an allylalcoholate freshly prepared from allyl alcohol (0.33 g, 5.8 mmol) and NaH (0.23 g, wt%, 5.8 mmol) in 3 ml of dimethylformamide was added to a solution of M1 (1.0 g, 1.2 mmol) in dimethylformamide (175 ml) while cooling with an ice bath. The reaction mixture was stirred for 1 minute and quickly quenched with 200 ml of water. Then it was poured into 2 M HCl and stirred at room temperature for 30 min. It was extracted several times with dichloromethane, the combined organic phases were washed with 1 M NaOH, then dried over magnesium sulfate, filtered and concentrated. Purification by silica gel column chromatography (100% dichloromethane) gave 5,12-bis(allyloxy)-2,9-bis(2,6-diisopropylphenyl)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone (M3) as a purple solid (0.24 g, 25%). 1 HNMR (400 MHz, CDCl3) δ 9.71 (d, J = 8.3 Hz, 2H), 8.73 (d, J = 8.3 Hz, 2H), 8.61 (s, 2H), 7.52 (t, J = 7.8 Hz, 2H), 7.39 (d, J = 7.8 Hz, 4H), 6.38 - 6.20 (m, 2H), 5.66 (dd, J = 17.3, 1.2 Hz, 2H), 5.51 (dd, J = 10.5, 1.2 Hz, 2H), 5.12 (d, J = 5.5 Hz, 4H), 2.80 (m, J = 6.8 Hz, 4H), 1.22 (d, J = 6.8 Hz, 24H).

[0147] Under nitrogen, allylamine (0.66 g, 12 mmol) was added to a solution of M1 (1.0 g, 1.2 mmol) in dimethylformamide (50 ml) at room temperature. The reaction mixture was stirred at 20 °C for 30 h. Another portion of allylamine (0.66 g, 12 mmol) was added and the reaction mixture was heated to 35 °C for 20 h. Then the reaction mixture was poured into 2 M HCl and stirred for 30 min. It was extracted several times with dichloromethane, the combined organic phases were washed with 1 M HCl, dried over magnesium sulfate, filtered and concentrated. Purification by silica gel column chromatography (100% dichloromethane) gave 5-(allylamino)-12-bromo-2,9-bis(2,6-diisopropylphenyl)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone (M4) as a green solid (0.16 g, 16%). 11H NMR (400 MHz, CDCl3) δ 9.53 (d, J = 8.2 Hz, 1H), 9.03 (s, 2H), 9.02 (d, J = 8.2 Hz, 1H), 8.75 (d, J = 8.2 Hz, 1H), 8.57 (d, J = 8.1 Hz, 1H), 8.35 (s, 1H), 7.57 - 7.48 (m, 2H), 7.38 (m, 4H), 6.10 (dd, J = 10.6, 5.5 Hz, 1H), 5.46 (dd, J = 17.2, 1.5 Hz, 1H), 5.38 (dd, J = 10.6, 1.5 Hz, 1H), 4.25 - 4.15 (m, 2H), 2.78 (sept, J = 6.8 Hz, 4H), 1.21 (d, J = 6.8 Hz, 24H).

[0148]

[0149] At room temperature, allyl 4-hydroxybenzoate (665 mg, 3.73 mmol) and potassium carbonate (515 mg, 3.73 mmol) were added to a solution of M1 (540 mg, 622 μmol) in dimethyl sulfoxide (8.8 ml), and the reaction mixture was stirred at 115 °C for 30 min. Then the reaction mixture was cooled to room temperature, poured into 2 M HCl, and stirred for 30 min. The orange precipitate was filtered, dissolved in dichloromethane, and extracted three times with 1 M NaOH. The combined organic phases were dried over magnesium sulfate, filtered, and concentrated to give diallyl 4,4'-((2,9-bis(2,6-diisopropylphenyl)-1,3,8,10-tetraoxo-1,2,3,8,9,10-hexahydroanthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-5,12-diyl)bis(oxy))dibenzoate (M5) as a red solid (600 mg, 96%). 1 1H NMR (400 MHz, CDCl3) δ 9.55 (d, J = 8.3 Hz, 2H), 8.73 (d, 8.3 Hz, 2H), 8.48 (s, 2H), 8.16 (d, J = 8.8 Hz, 4H), 8.07 (d, J = 8.8 Hz, 4H), 7.50 (t, J = 7.8 Hz, 2H), 7.35 (d, J = 7.8 Hz, 4H), 7.21 (d, J = 7.8 Hz, 4H), 7.16 (d, J = 7.8 Hz, 4H), 6.09 - 6.02 (m, 2H), 5.45 - 5.40 (m, 2H, 2H), 5.33 - 5.29 (m, 2H), 4.86 - 4.82 (m, 4H), 2.73 (sept, J = 6.8 Hz, 3H), 1.18 - 1.16 (m, 24H).

[0150]

[0151] At 0 °C, a solution of boron tribromide (1.31 mL, 13.8 mmol) in 5 mL of dichloromethane was added dropwise to M2 (2.20 g, 2.30 mmol) in dichloromethane (28 mL), and the reaction mixture was stirred at 20 °C for 20 h. The reaction mixture was cooled in an ice bath, hydrolyzed slowly with methanol, and then concentrated. The crude product was dissolved in methanol, precipitated by the addition of water, and then filtered. The resulting paste was dried overnight in a vacuum oven at 80 °C to give 2,9-bis(2,6-diisopropylphenyl)-5,12-bis(4-hydroxyphenoxy)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone as a purple solid (2.15 g, 93%). The crude product was used without further purification. 1 H NMR (400 MHz, acetone) δ 9.79 (d, J = 8.3 Hz, 2H), 8.70 (d, J = 8.3 Hz, 2H), 8.35 (s, 2H), 7.50 - 7.43 (m, 2H), 7.36 (d, J = 7.9 Hz, 4H), 7.26 (d, J = 8.7 Hz, 4H), 7.02 (d, J = 8.7 Hz, 4H), 2.82 (m, 4H), 1.18 - 1.11 (m, 24H).

[0152] Potassium carbonate (513 mg, 3.71 mmol) and 3-bromoprop-1-ene (321 μL, 3.71 mmol) were added to a solution of 2,9-bis(2,6-diisopropylphenyl)-5,12-bis(4-hydroxyphenoxy)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone (430 mg, 464 μmol) in acetonitrile (9.7 mL), and the reaction mixture was stirred in a microwave oven at 100 °C for 6 h. The reaction mixture was concentrated, the crude product was dissolved in dichloromethane, and extracted three times with 1 M HCl. The combined organic phases were dried over magnesium sulfate, filtered, and concentrated to give 5,12-bis(4-(allyloxy)phenoxy)-2,9-bis(2,6-diisopropylphenyl)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone (M6) as a red-pink solid (400 mg, 86%). 11H NMR (400 MHz, CDCl3) δ 9.71 (d, J = 8.3 Hz, 2H), 8.73 (d, J = 8.3 Hz, 2H), 8.42 (s, 2H), 7.52 - 7.46 (m, 2H), 7.37 - 7.30 (m, 4H), 7.18 - 7.14 (m, 4H), 7.04 - 7.0 (m, 4H), 6.10 (ddt, J = 17.3, 10.5, 5.3 Hz, 2H), 5.46 (dq, J = 17.3, 1.6 Hz, 2H), 5.38 - 5.28 (m, 4H), 4.59 (dt, J = 5.3, 1.6 Hz, 4H), 2.83 - 2.66 (m, 4H), 1.25 - 1.10 (m, 24H).

[0153]

[0154] To a solution of 2,9-bis(2,6-diisopropylphenyl)-5,12-bis(4-hydroxyphenoxy)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone (2.0 g, 2.16 mmol) in tetrahydrofuran (26 mL) was added triethylamine (1.80 mL, 12.9 mmol) and acryloyl chloride (1.05 mL, 12.9 mmol), and the reaction mixture was stirred at 20 °C for 60 minutes. The reaction mixture was then concentrated, suspended in water, and filtered. The crude product was dissolved in dichloromethane and extracted with 1 M NaOH. The combined organic phases were dried over magnesium sulfate, filtered, and concentrated. Purification by silica gel column chromatography (100% dichloromethane) afforded ((2,9-bis(2,6-diisopropylphenyl)-1,3,8,10-tetraoxo-1,2,3,8,9,10-hexahydroanthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-5,12-diyl)bis(oxy))bis(4,1-phenylene) diacrylate (M7) as a red solid (2.20 g, 85%). 1 1H NMR (400 MHz, CDCl3) δ 9.64 (d, J = 8.3 Hz, 2H), 8.74 (d, J = 8.3 Hz, 2H), 8.48 (s, 2H), 7.54 - 7.46 (m, 2H), 7.39 - 7.30 (m, 4H), 7.26 - 7.20 (m, 8H), 6.64 (dd, J = 17.3, 1.3 Hz, 2H), 6.35 (dd, J = 17.3, 10.4 Hz, 2H), 6.06 (dd, J = 10.4, 1.3 Hz, 2H), 2.75 (sept, J = 6.3 Hz, 4H), 1.19 - 1.16 (m, 24H).

[0155]

[0156] To a solution of M1 (535 mg, 616 μmol) in dimethylformamide (23.8 ml) was added K2CO3 (255 mg, 1.85 mmol) and 4-(2-hydroxyethyl)phenol (255 mg, 1.85 mmol), and the reaction mixture was stirred at 110 °C for 2 h. The reaction mixture was cooled to room temperature and then poured into 2 M HCl. The pink precipitate was filtered, dissolved in dichloromethane, and extracted twice with 1 M NaOH. The combined organic phases were dried over magnesium sulfate, filtered, and concentrated to give 2,9-bis(2,6-diisopropylphenyl)-5,12-bis(4-(2-hydroxyethyl)phenoxy)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone as a pink solid (500 mg, 82%). 1 H NMR (400 MHz, CDCl3) δ 9.65 (d, J = 8.3 Hz, 2H), 8.72 (d, J = 8.3 Hz, 2H), 8.45 (s, 2H), 7.51 - 7.47 (m, 2H), 7.39 - 7.29 (m, 8H), 7.20 - 7.12 (m, 4H), 3.93 (t, J = 6.4 Hz, 4H), 2.93 (t, J = 6.4 Hz, 4H), 2.74 (sept, J = 6.7 Hz, 1H), 1.19 - 1.15 (m, 24H).

[0157] To a solution of 2,9-bis(2,6-diisopropylphenyl)-5,12-bis(4-(2-hydroxyethyl)phenoxy)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone (570 mg, 580 μmol) in tetrahydrofuran (7 ml) at 20 °C was added dropwise triethylamine (342 μL, 2.45 mmol) and acryloyl chloride (241 μL, 2.98 mmol) diluted in 2 ml of tetrahydrofuran. The reaction mixture was stirred for 1 h. The reaction mixture was then concentrated, suspended in water, and filtered. The crude product was dissolved in dichloromethane and extracted three times with 1 M NaOH. The combined organic phases were dried over magnesium sulfate, filtered, and concentrated to give (((2,9-bis(2,6-diisopropylphenyl)-1,3,8,10-tetraoxo-1,2,3,8,9,10-hexahydroanthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-5,12-diyl)bis(oxy))bis(4,1-phenylene))bis(ethane-2,1-diyl) diacrylate (M8) as a dark pink solid (620 mg, 98% yield). 11H NMR (400 MHz, CDCl3) δ 9.66 (d, J = 8.3 Hz, 2H), 8.73 (d, J = 8.3 Hz, 2H), 8.45 (s, 2H), 7.49 (t, J = 7.8 Hz, 2H), 7.37 - 7.33 (m, 8H), 7.17 - 7.14 (m, 4H), 6.41 (dd, J = 17.3, 1.4 Hz, 2H), 6.14 (dd, J = 17.3, 10.4 Hz, 2H), 5.84 (dd, J = 10.4, 1.4 Hz, 2H), 4.42 (t, J = 6.9 Hz, 4H), 3.04 (t, J = 6.7 Hz, 4H), 2.74 (m, J = 6.7 Hz, 3H), 1.19 - 1.15 (m, 24H).

[0158]

[0159] Under argon, potassium carbonate (167 mg, 1.21 mmol) and 4-(2-hydroxyethoxy)phenol (186 mg, 1.21 mmol) were added to a solution of M1 (350 mg, 403 μmol) in dimethylformamide (3 ml), and the reaction mixture was stirred at 95 °C for 2 h. The reaction mixture was cooled to room temperature and then poured into 2 M HCl. The purple precipitate was filtered, dissolved in dichloromethane, and extracted twice with 1 M NaOH. The combined organic phases were dried over magnesium sulfate, filtered, and concentrated to give 2,9-bis(2,6-diisopropylphenyl)-5,12-bis(4-(2-hydroxyethoxy)phenoxy)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone as a purple-pink solid (318 mg, 78%). 1 1H NMR (400 MHz, CDCl3) δ 9.68 (d, J = 8.3 Hz, 2H), 8.72 (d, J = 8.3 Hz, 1H), 8.38 (s, 2H), 7.46 (t, J = 7.8 Hz, 2H), 7.31 (d, J = 7.8 Hz, 4H), 7.17 - 7.12 (m, 4H), 7.04 - 6.99 (m, 4H), 4.12 (m, 4H), 3.99 (m, 4H), 2.79 - 2.63 (m, 4H), 2.0 (t, J = 6.2 Hz, 2H), 1.21 - 1.09 (m, 24H).

[0160] To a solution of 2,9-bis(2,6-diisopropylphenyl)-5,12-bis(4-(2-hydroxyethoxy)phenoxy)anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone (300 mg, 296 μmol) in tetrahydrofuran (3.6 ml) was added dropwise diluted triethylamine (179 mg, 1.77 mmol) and acryloyl chloride (160 mg, 1.77 mmol). The reaction mixture was stirred at 20 °C for 60 min. Then the reaction mixture was concentrated, suspended in 2 M HCl, and filtered. The crude product was dissolved in dichloromethane and extracted three times with 1 M NaOH. The combined organic phases were dried over magnesium sulfate, filtered, and concentrated to give (((2,9-bis(2,6-diisopropylphenyl)-1,3,8,10-tetraoxo-1,2,3,8,9,10-hexahydroanthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-5,12-diyl)bis(oxy))bis(4,1-phenylene))bis(oxy))bis(ethane-2,1-diyl) diacrylate (M9) as a dark pink solid (300 mg, 90% yield). 1 HNMR (400 MHz, CDCl3) δ 9.67 (d, J = 8.3 Hz, 2H), 8.71 (d, J = 8.3 Hz, 2H), 8.38 (s, 2H), 7.51 - 7.43 (m, 2H), 7.32 (d, J = 7.8 Hz, 4H), 7.17 - 7.10 (m, 4H), 7.03 - 6.97 (m, 4H), 6.46 (dd, J = 17.3, 1.4 Hz, 2H), 6.17 (dd, J = 17.4, 10.4 Hz, 2H), 5.87 (dd, J = 10.4, 1.4 Hz, 2H), 4.58 - 4.50 (m, 4H), 4.28 - 4.21 (m, 4H), 2.71 (sept, J = 6.7 Hz, 6H), 1.23 - 1.09 (m, 24H).

[0161] Preparation of UV-curable safety inkjet ink composition

[0162] The viscosities of the ink carriers V1 - V4 were determined using a Brookfield DV1 LV viscometer equipped with a spindle LV1 at a rotational speed of 30 rpm and a temperature of 45 °C.

[0163] The ink carrier (V1, Table 1A) was prepared as follows: Each component was added one by one to a brown polypropylene bottle and dispersed using a high-shear mixer Silverson L5M-A equipped with a square hole screen. After each addition, the mixture was dispersed at approximately 5000 rpm for about 5 minutes. Finally, the mixture was manually filtered using a 5-μm nylon syringe filter.

[0164] Table 1A

[0165]

[0166] The ink carriers (V2 - V4, Table 1B) were independently prepared as follows: Each component was added one by one to a brown polypropylene bottle and dispersed using a high-shear mixer Silverson L5M-A equipped with a square hole screen. After each addition, the mixture was dispersed at approximately 5000 rpm for about 5 minutes. Finally, the mixture was manually filtered using a 5-μm nylon syringe filter.

[0167] Table 1B

[0168]

[0169] The security ink (Tables 2A and 2B) was prepared as follows: The markers were independently added to the ink carrier and the mixture was placed in an ultrasonic bath for 20 minutes. Then the security ink was left at room temperature for 12 to 24 hours before use.

[0170] Table 2A

[0171]

[0172] Table 2B

[0173]

[0174] Preparation of Security Features

[0175] The substrate for the preparation of security features was the black and white unsealed test sheet Leneta N2C-2 obtained from Leneta Company Inc. The white part of the substrate was non-fluorescent white paper.

[0176] A rectangular-shaped security feature with dimensions of 13 cm × 10 cm was prepared by manually printing the corresponding UV-curable security ink compositions C1-C12 and E1-E6 on the white part of a Leneta N2C-2 substrate using a semi-automatic coater (Kcontrol coater from RK print, model 001) equipped with a rod coating #1 (theoretical thickness of about 6 μm) to independently form layers. The manual printing method was used to simulate inkjet printing, particularly drop-on-demand (DOD) inkjet printing.

[0177] Then, the obtained layers were independently at least partially cured with a UV-LED light source (IST LUV20) at a dose of 385 nm and 200 mJ / cm 2 .

[0178] A security feature in the form of a QR code with dimensions of 1.5 cm × 1.5 cm was prepared as Figure 1 shown: The composition of Example E6 was applied to the white part of the substrate Leneta N2C-2 by drop-on-demand inkjet printing using a KM1024i inkjet head (Konica Minolta), and the printed composition was cured using an IST LUV20 LED-UV lamp (385 nm, 200 mJ / cm 2 ).

[0179] Performance of the security feature

[0180] Fluorescence intensity

[0181] The fluorescence intensity of the security features made from the UV-cured compositions E1-E6 and the comparative compositions C1-C12 was obtained by measuring the full fluorescence spectrum emitted by the security features on a Fluorolog III instrument (Horiba Sicientific), using the following parameters:

[0182] - R13456 photomultiplier tube (PFR Technologies LLC) (185 - 950 nm)

[0183] - Configuration: FL3-22

[0184] - Angle: 30°

[0185] - Position: Front

[0186] For each series of measurements, the excitation and detection slits were fixed and are shown in Tables 3A - 3B. Only measurements made with the same excitation and detection slits can be directly compared.

[0187] The excitation wavelength (as shown in Tables 3A and 3B) corresponds to the excitation maximum of each marker. To determine the excitation maximum, the emission spectrum is measured using an excitation wavelength close to the estimated maximum. Then the excitation spectrum is recorded at the emission maximum wavelength, and the final emission spectrum is obtained by irradiating at the determined excitation maximum.

[0188] The maximum fluorescence intensity is derived from the emission spectrum and is expressed in Tables 3A - 3B as the maximum absolute fluorescence intensity (photons / second). Relative values (%) are also given by comparison with the fluorescence intensities of compositions E1 (without colorant) and E4 - E6 (with colorant).

[0189] Light fastness

[0190] The lightfastness of a security feature made from a cured UV - curable security ink composition is determined by subjecting the security feature to the Xenotest procedure (Norm ISO 105B02). The measurement parameters are as follows.

[0191] - Device: Xenotest 220+ (Atlas MTT GmbH)

[0192] - Xenon lamp (2200W, 42W / m 2 )

[0193] - Conditions: 35 °C (test chamber), 48% (black BST panel), 40% relative humidity

[0194] - Ventilator speed: 2500 rpm

[0195] - Filter: <320 nm

[0196] The security feature is irradiated in the Xenotest device for exposure times of 3, 7, 24, 48, 72 hours. After each step, the fluorescence spectrum is recorded, the maximum fluorescence intensity is determined from the spectrum, and compared with the maximum fluorescence intensity before aging. When the measured maximum fluorescence intensity drops below 50% of the initial value, the lightfastness value is assigned between 1 and 4 according to the following scale:

[0197]

[0198]

[0199]

[0200] It is clearly seen from the data of the examples that even at low concentrations, the examples of the present invention exhibit a suitable and advantageous performance balance with respect to fluorescence intensity and more specifically improved light resistance. The examples also provide optimal printing properties, especially when incorporated into an inkjet security ink composition. The uniformity of the UV curable ink compositions E1-E6 is indicative of the compatibility of the marker in the colored or uncolored UV curable security ink composition, especially with respect to solubility.

Claims

1. A UV-curable security ink composition, comprising: a) about 40 to about 95% by weight, preferably about 60 to 95% by weight, of one or more free-radical curable monomers, one or more oligomers, or mixtures thereof; b) about 0.1 to about 20% by weight, preferably about 1 to 15% by weight, of at least one free-radical photoinitiator; c) about 0.005 to about 5% by weight, preferably about 0.01 to 1% by weight, of at least one compound P, where P is a compound having a structure selected from the group consisting of (1) and (2) wherein (W) is a perylene substructure, which preferably comprises any one of a perylene, triphenylene, or quaterrylene core structure and comprises at least one substituent of formula (3) attached to the perylene substructure (W), R 1 、R 2 、R 3 are independently a carbocyclic or heterocyclic substituent, wherein R 1 and R 2 are attached to, preferably directly attached to, the imide N of the perylene substructure (W), and in the case of compound (2), R 3 is directly attached to the naphthalene ring, wherein -----represents an optionally present R 3 Substituent Ar 4 is an aromatic substituent, Y is a linker, R’ is H or methyl; d) optionally about 0.1 to about 2% by weight of at least one photosensitizer; e) optionally about 0.1 to about 20% by weight of at least one colorant; f) optionally about 0.01 to about 10% by weight of at least one additive, preferably about 0.01 to about 1% by weight of at least one surfactant; % by weight is based on the total weight of the UV-curable security ink composition.

2. The UV-curable security ink composition according to claim 1, wherein the free-radical photoinitiator is selected from the group consisting of: aminoketone compounds, hydroxyketone compounds, alkoxyketone compounds, acetophenone compounds, benzophenone compounds, ketosulfone compounds, benzyl ketal compounds, benzoin ether compounds, glyoxylate compounds, phosphine oxide compounds, and mixtures thereof, preferably selected from the group consisting of phosphine oxide compounds.

3. The UV-curable security ink composition according to claim 1 or 2, wherein the at least one photosensitizer is a thioxanthone compound.

4. The UV-curable security ink composition according to claims 1 to 3, wherein the ink composition comprises about 0% by weight of the at least one colorant, and wherein the at least one compound P is present in a total amount of about 0.005% by weight to about 0.2% by weight, % by weight based on the total weight of the UV-curable security ink composition.

5. The UV-curable security ink composition according to claims 1 to 3, wherein the ink composition comprises about 0.1% by weight to about 20% by weight, preferably about 5 to about 10% by weight, of the at least one colorant, and wherein the at least one compound P is present in a total amount of about 0.05% by weight to about 1.0% by weight, % by weight based on the total weight of the UV-curable security ink composition.

6. The UV-curable security ink composition according to claim 5, wherein the at least one colorant is an IR-transparent pigment or an IR-transparent dye.

7. The UV curable safety ink composition according to claims 1 to 6, wherein the linker Y is selected from the group consisting of: -(CH2) j -, -O-(CH2) k -, -[-(CH2) l -O] m -(CH2) p , and wherein j = 0 to 6, k = 1 to 6, l = 1 to 3, m = 1 to 3, p = 1 to 3.

8. The UV curable safety ink composition according to any one of claims 1 to 7, wherein R 1-3 The substituent is an aromatic substituent.

9. The UV-curable safety ink composition according to claim 8, wherein R 1-3 The substituents independently have the structure (4); wherein R 4 , R 5 and R 6 are independently hydrogen, C1-C4 alkyl and its isomers, C1-C4 alkoxy, C1-C4 aminoalkyl or (fused) aromatic group.

10. The UV curable safety ink composition according to claims 1 to 7, wherein R 3 The substituent is a heterocyclic substituent, preferably an N-containing heterocyclic substituent.

11. The UV-curable security ink composition according to any one of claims 1 to 10, wherein the ink composition is a screen printing ink composition having a viscosity of about 50 mPa·s to about 3000 mPa·s at 25°C, a flexographic printing ink composition having a viscosity of about 50 mPa·s to about 2000 mPa·s at 25°C, a gravure printing ink composition having a viscosity of about 50 mPa·s to about 1000 mPa·s at 25°C, and a non-contact fluid microdispensing process ink composition having a viscosity of about 1 mPa·s to about 1000 mPa·s at 25°C.

12. The UV-curable security ink composition according to claim 11, wherein the ink composition is a non-contact fluid microdispensing process printing ink composition, preferably an inkjet printing ink composition, more preferably a drop-on-demand (DOD) inkjet printing ink composition having a viscosity below 30 mPa·s at 25°C.

13. A security feature made of a cured layer of the security ink composition according to any one of claims 1 to 12.

14. A security document or article comprising the security feature according to claim 13.

15. A method for preparing the security feature according to claim 13, comprising the following steps: a) applying the UV-curable security ink composition according to any one of claims 1 to 12 to a substrate, preferably by a printing process; and b) at least partially curing the UV-curable security ink composition from step a), wherein the curing is preferably carried out using a UV-LED light source, more preferably having a wavelength of about 360 nm to about 410 nm.

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