Printing inks

Abstract

The invention provides an oxidative drying intaglio ink.

Description

[0001] PRINTING INKS

[0002] Field of the invention

[0003] The present invention relates to the field of oxidative drying inks suitable for intaglio printing of value documents and intaglio printing processes using oxidative drying inks.

[0004] Background of the invention

[0005] With the constantly improving quality of color photocopies and prints and, in an attempt, to protect security documents such as banknotes, value documents or cards, transportation tickets or cards, tax banderols, and product labels that have no reproducible effects against counterfeiting, falsifying or illegal reproduction, it has been the conventional practice to incorporate various security features in such documents.

[0006] Intaglio printing processes refer to printing methods and processes used in particular in the field of value documents. The intaglio printing process is known to be the most consistent and high-quality printing process for producing fine tapering lines and is therefore the printing technology of choice for fine design in the field of security documents, in particular banknotes and stamps. One of the distinguishing features of the intaglio printing process is that the thickness of the ink transferred to the substrate may be varied from a few micrometers to several tens of micrometers by using correspondingly shallow or deep engravings on the intaglio printing plate. The thickness of intaglio printed security features thus allows a relatively high amount of material on the substrate which can be useful for detection and sensing.

[0007] Oxidative drying inks are commonly used for intaglio printing processes. These inks dry by oxidation in the presence of oxygen, in particular in the presence of the oxygen of the atmosphere. During the drying process, the oxygen combines with one or more components of the ink vehicle, converting the ink to a semi-solid or a solid state. The process may be accelerated by the use of driers also referred in the art as catalysts, siccative agents, desiccatives or desiccators, such as metallic salts, and / or by the application of a thermal treatment.

[0008] Oxidative drying intaglio inks may suffer from a so-called “set-off’ problem which is the transfer of ink from one printed sheet to the back side of the following printed sheet in the stack, or to the back of an endless sheet in a web. Although this problem may be encountered with any industrial printing process using oxidative drying inks, the pronounced relief of intaglio printed patterns (i.e. thickness) may accentuate the problem of set-off. With state-of-the-art oxidative drying intaglio inks, the set-off issue has been reduced mainly through optimization of the ink formulation.

[0009] There remains a need for intaglio printing processes using oxidative drying intaglio for producing security feature exhibiting good drying performance and set-off characteristics so as to avoid set-off problems.

[0010] Summary of the invention

[0011] In a first aspect, the invention provides an oxidative drying intaglio ink, comprising:

[0012] (1) one or more oxidative drying varnishes;

[0013] (2) one or more driers;

[0014] (3) one or more waxes of general Formula I: wherein a is an integer from 6 to 24, b is an integer from 2 to 6, c is an integer from 2 to 6, m is 1 to 6, n is 8 to 15, and the CH2groups designated with an asterisk (*) and / or a dagger (t) may have one hydrogen replaced with a Ci_2-alkyl substituent;

[0015] (4) one or more fillers and extenders; and

[0016] (5) one or more solvents.

[0017] In a second aspect, the invention provides a process for producing a security feature on a substrate by an intaglio printing process, said process comprising the steps:

[0018] A) inking an intaglio engraved printing plate with an oxidative drying intaglio ink, said oxidative drying intaglio ink comprising:

[0019] (1) one or more oxidative drying varnishes;

[0020] (2) one or more driers; and

[0021] (3) one or more waxes of general Formula I: wherein a is an integer from 6 to 24, b is an integer from 2 to 6, c is an integer from 2 to 6, m is 1 to 6, n is 8 to 15, and the CH2groups designated with an asterisk (*) and / or a dagger (t) may have one hydrogen replaced with a Ci.2-alkyl substituent;

[0022] (4) one or more fillers and extenders; and

[0023] (5) one or more solvents;

[0024] B) removing excess of oxidative drying intaglio ink; C) transferring the oxidative drying intaglio ink in the form of the security feature on the substrate; and

[0025] D) drying the oxidative drying intaglio ink in the presence of air so as to form the security feature.

[0026] In a third aspect, the invention provides a security feature made by the process of the invention.

[0027] In a fourth aspect, the invention provides a security feature made using the oxidative drying intaglio ink of the invention.

[0028] Detailed description

[0029] The following definitions are to be used to interpret the meaning of the terms discussed in the description and recited in the claims.

[0030] As used herein, the article "a" indicates one as well as more than one and does not necessarily limit its referent noun to the singular.

[0031] As used herein, the terms “about” means that the amount or value in question may be the value designated or some other value about the same. The phrases are intended to convey that similar values within a range of ±5% of the indicated value promote equivalent results or effects according to the invention.

[0032] As used herein, the term “and / or” or “or / and” means that either all or only one of the elements of said group may be present. For example, “A and / or B” shall mean “only A, or only B, or both A and B”.

[0033] As used herein, the term “at least one” is meant to define one or more than one, for example one or two or three.

[0034] The term “security feature” is used to denote an image, pattern or graphic element that can be used for authentication purposes.

[0035] As used herein, the expression “eq PS” means “equivalent to polystyrene” and is used to indicate that the quoted molecular weight is measured using GPC against polystyrene standards.

[0036] As used herein “molecular weight” refers to the number average molecular weight (Mn).

[0037] Abbreviations

[0038] PS polystyrene

[0039] GPC gel permeation chromatography

[0040] PVC poly(vinylchloride)

[0041] TW transparent white The present invention provides oxidative drying intaglio inks suitable for intaglio printing processes, in particular for intaglio printing processes for producing security features on value documents. The inventors have surprisingly found that when the oxidative drying intaglio inks comprise a wax of general Formula I, excellent set-off and counter-pressure resistance result.

[0042] The various ingredients of the inks of the invention will now be described in greater detail.

[0043] Oxidative drying varnish

[0044] The inks of the invention comprise one or more oxidative drying varnishes. The term “varnish” is also referred to in the art as resin, binder or ink vehicle. The at least one oxidative drying varnish is preferably present in the oxidative drying intaglio inks of the invention in an amount from at or about 10 to at or about 80 wt%, more preferably at or about 20 to at or about 60 wt%, when the ink does not comprise pigments, and from about 5 to about 60 wt%, more preferably about 10 to about 50 wt% when the ink comprises pigment, the weight percents being based on the total weight of the oxidative drying intaglio ink.

[0045] Preferred oxidative drying varnishes are polymers comprising unsaturated fatty acid residues, saturated fatty acids residues or mixtures thereof, as generally known in the art. Preferably the oxidative drying varnishes used in the inks of the invention comprise unsaturated fatty acid residues to ensure the air-drying properties. Particularly preferred oxidative drying varnishes are resins comprising unsaturated acid groups, even more preferred are resins comprising unsaturated carboxylic acid groups. However the resins may also comprise saturated fatty acids residues. Preferably the oxidative drying varnishes used in the inks of the invention comprise acid groups, i.e. the oxidative drying varnishes are selected from acid-modified resins. The oxidative drying varnishes used in the inks of the invention may be selected from the group consisting of alkyd resins, vinyl polymers, polyurethane resins, polyesters, hyperbranched resins, rosin-modified maleic resins, rosin-modified phenol resins, rosin esters, petroleum resin-modified rosin esters, petroleum resin-modified alkyd resins, alkyd resin- modified rosin / phenol resins, alkyd resin-modified rosin esters, acrylic-modified rosin / phenol resins, acrylic-modified rosin esters, urethane-modified rosin / phenol resins, urethane- modified rosin esters, urethane-modified alkyd resins, epoxy-modified rosin / phenol resins, epoxy-modified alkyd resins, terpene resins, nitrocellulose resins, polyolefins, polyamides, acrylic resins and combinations or mixtures thereof. The expressions “polymer” and “resin” are used interchangeably herein.

[0046] Saturated and unsaturated fatty acid compounds are usually obtained from animal or vegetal sources. Examples of animal sources include animal fat, butter fat, fish oil, lard, liver fats, tuna fish oil, sperm whale oil and / or tallow oil. Examples of plant sources include oils such as vegetable oils and / or non-vegetable oils. Examples of plant oils include without limitation bitter gourd, borage, calendula, canola, castor (that may be dehydrated in a separate step), China wood, coconut, conifer seed, corn, cottonseed, flaxseed, grape seed, Jacaranda mimosifolia seed, linseed oil, palm, palm kernel, peanut, pomegranate seed, rapeseed, safflower, snake gourd, soya (bean), sunflower, tall, tung and wheat germ. Suitable fatty acids obtained therefrom by chemical processes include, for example, myristoleic acid (C14H26O2, CAS No 544-64-9), palmitoleic acid (Ci6H3o02, CAS No 373-49-9), oleic acid (C18H34O2, CAS No 1 12- 80-1), a-eleostearic acid (C18H30O2, CAS No 506-23-0), licanic acid (C18H28O3, CAS No 623- 99-4), linoleic acid (C18H32O2, CAS No 60-33-3), linolenic acid (C18H30O2, CAS No 463-40-1), stearidonic acid (CI8H28O2, CAS No 20290-75-9), arachidonic acid (C20H32O2, CAS No 506- 32-1), ricinoleic acid (C18H34O3, CAS No 141-22-0), erucic acid (C22H42O2, CAS No 1 12-86-7), gadoleic acid (C20H38O2, CAS No 29204-02-2), clupanodonic acid (C22H34O2, CAS No 24880- 45-3), nisinic acid (C24H36O2, CAS No 68378-49-4) and mixtures thereof. Such fatty acids are typically used in the form of mixtures.

[0047] In one embodiment, the oxidative drying varnish is a polyester, preferably a partially neutralized acidified polyester. In one embodiment, the oxidative drying varnish is a partially neutralized acidified polyester which is a condensation product of conjugated fatty acids, one or more diacids, and one or more polyols.

[0048] In another embodiment, the oxidative drying varnish is a product of conjugated sunflower oil fatty acids, isophthalic acid, tetrahydrophthalic anhydride, trimethylolpropane and pentaerythritol.

[0049] In another embodiment, the oxidative drying varnish is a product of conjugated sunflower oil fatty acids at about 32.8 wt%, isophthalic acid at about 13.1 wt%, tetrahydrophthalic anhydride at about 12.8 wt%, trimethylolpropane at about 8.6 wt%, and pentaerythritol at about 7.4 wt%, neutralized with potassium hydroxide and dodecyl benzenesulfonic acid salt of 2-amino- propane, the weight percents being based on the total weight of the oxidative drying varnish.

[0050] Driers

[0051] The inks of the invention comprise one or more driers. Oxidative drying inks dry by oxidation in the presence of oxygen, in particular in the presence of the oxygen in the atmosphere. During the drying process, the oxygen combines with one or more components of the ink, setting off a chain of reactions that convert the ink to a solid state. The inks of the invention comprise one or more driers (also referred in the art as catalysts, siccatives and siccative agents) to speed up the oxidation process. Examples of driers include inorganic or organic salts of metal(s), metallic soaps of organic acids, metal complexes and metal complex salts. Suitable salts of metal(s) include salts containing cobalt, calcium, copper, zinc, iron, zirconium, manganese, barium, zinc, strontium, lithium, vanadium and potassium as the cation(s); and halides, nitrates, sulphates, carboxylates like acetates, ethylhexanoates, neodecanoates, octanoates and naphtenates or acetoacetonates as the anion(s) such as for example ethylhexanoates or neodecanoates of cobalt, manganese and zirconium. Suitable examples of metal complexes and metal complex salts include manganese, vanadium and iron compounds (i.e. manganese complexes, manganese complex salts, vanadium complexes, vanadium complex salts, iron complexes and iron complex salts).

[0052] In a preferred embodiment, the drier is a mixture of manganese(ll) salts and cobalt(ll) salts, particularly a mixture of 2-ethylhexanoate salts of Mn++and Co++.

[0053] In another preferred embodiment, the drier is chloro[ / 'e / -1 ,5-dimethyl (1 R,2S,4R,5S)-9,9- dihydroxy-3-methyl-2,4-di(2-pyridinyl-K / \ / )-7-[(2-pyridinyl-K / \ / )methyl]-3,7- diazabicyclo[3.3.1]nonane-1 ,5-dicarboxylate-K / \ / 3,K / \ / 7]-iron (1 +) chloride (1 :1) (CAS 478945- 46-9) sold by Borchers as Borchi® OXY-Coat 1410, in particular together with Mn and / or Zr salts, in particular Mn neodecanoates and Zr neodecanoates.

[0054] The one or more driers used in the inks of the invention are preferably present in a total amount from at or about 0.01 wt% to about 10 wt%, more preferably in a total amount from at or about 0.1 wt% to about 5 wt%, the weight percents being based on the total weight of the oxidative drying intaglio ink.

[0055] In a particularly preferred embodiment, the drier is a mixture of 2-ethylhexanoate salts of Mn++and Co++, used at at or about 0. 1 to at or about 5 wt%, based on the total weight of the oxidative dying intaglio ink.

[0056] Waxes

[0057] The inks of the invention comprise one or more waxes of general Formula I: wherein a is an integer from 6 to 24, b is an integer from 2 to 6, c is an integer from 2 to 6, m is 1 to 6, n is 8 to 15, and the CH2 groups designated with an asterisk (*) and / or a dagger (t) may have one hydrogen replaced with a Ci.2-alkyl substituent.

[0058] In a preferred embodiment, a is an integer from 6 to 22, more preferably 10 to 20, particularly preferably a is 16. In a preferred embodiment, b is an integer from 2 to 4, more preferably 2 to 3. In a particularly preferred embodiment, b is 2. In another particularly preferred embodiment, b is 3.

[0059] In another preferred embodiment, b is 2, and one of the carbons designated with an asterisk (*) in each C2 linkage bears a methyl group.

[0060] In a preferred embodiment, c is an integer from 2 to 4, more preferably 2 to 3. In a particularly preferred embodiment, c is 2. In another particularly preferred embodiment, c is 3.

[0061] In another preferred embodiment, c is 2, and one of the carbons designated with a dagger (t) in each C2linkage bears a methyl group.

[0062] In a preferred embodiment, b and c are both 2. In another preferred embodiment, b and c are both 3.

[0063] In another preferred embodiment, b and c are both 2, and one of the carbons designated with an asterisk (*) in each C2linkage and one of the carbons designated with a dagger (t) in each C2linkage bears a methyl group.

[0064] In another preferred embodiment, b and c are both 3, and none of the carbons designated with an asterisk (*) or a dagger (t) bears an alkyl group.

[0065] In one embodiment, m is about 1.5 to about 4, preferably m is about 1.75 to about 3.5, more preferably m is about 1 .8 to about 2.9.

[0066] In one embodiment, n is about 8 to about 12, preferably n is about 8.5 to about 11 , more preferably n is about 9.5 to about 10.7.

[0067] In one embodiment, m is about 1.5 to about 4, preferably m is about 1.75 to about 3.5, more preferably m is about 1.8 to about 2.9, and n is about 8 to about 12, preferably n is about 8.5 to about 11 , more preferably n is about 9.5 to about 10.7.

[0068] In one embodiment, m is about 1 .8 to about 2.9 and n is about 9.5 to about 10.7.

[0069] In one embodiment, a is 16, b and c are 2, one of the carbons designated with an asterisk (*) in each C2linkage and one of the carbons designated with a dagger (t) in each C2linkage bear a methyl group, n is about 9 to about 10, and m is about 2 to about 2.2. In another embodiment, a is 16, b and c are 3, n is about 10 to about 11 , and m is about 1.8 to about 2.1.

[0070] In another embodiment, a is 16, b and c are 2, n is about 9.8 to about 10, and m is about 2.6 to about 3.

[0071] In another embodiment, the one or more waxes is a copolymer of saturated Ci8-dioic acid and polypropylene glycol, OH-terminated, i.e. general Formula I, wherein a=16, b=c=2 (with one carbon in each C2linkage bearing a methyl group), m is about 2.12 and n is about 9.63.

[0072] In another embodiment, the one or more waxes is a copolymer of saturated Ci8-dioic acid and poly(1 ,3-propane diol), OH-terminated, i.e. general Formula I, wherein a=16, b=c=3, m is about 1.91 and n is about 10.63.

[0073] In another embodiment, the one or more waxes is a copolymer of saturated Ci8-dioic acid and polyethylene glycol, OH-terminated, i.e. general Formula I, wherein a=16, b=c=2, m is about 2.88 and n is about 9.91.

[0074] The one or more waxes of general Formula I preferably has a number average molecular weight of from about 3,500 g / mol eq PS to about 6,000 g / mol eq PS, more preferably from about 3,900 g / mol eq PS to about 5,000 g / mol eq PS, particularly preferably from about 4,000 g / mol eq PS to about 4,500 g / mol eq PS.

[0075] The number average molecular weights (Mn) of the waxes of general Formula I can be determined by GPC (gel permeation chromatography) according to OECD test method 118. In a specific example, a Malvern Viskotek GPCmax was used. The device is equipped with an isocratic pump, a degasser, an autosampler, the detector being a differential refractometer. A calibration curve [log(molecular mass) vs f(retention volume)] is established using six polystyrene standards (with molecular masses ranging from 472 to 512,000 g / mol) and n- hexylbenzene being used for as the standard for the smallest molecular mass (M = 162 g / mol). Two columns Viskotek TM4008L (column length 30.0 cm, internal diameter 8.0 mm) are coupled in series. The stationary phase is made of a styrene-divinylbenzene copolymer with a particle size of 6 pm and a maximum pore size of 3000 A. During the measurement, the temperature is fixed at 35°C. The analyzed samples contain 10 mg / mL of wax of general Formula I dissolved in THF, and are injected at a rate of 1 mL / min. The molecular mass of the waxes of general Formula I is calculated from the chromatogram as a polystyrene-equivalent number average molecular weight (PS eq Mn) using the following formula: where H, is the level of the detector signal (differential refractometer) from the baseline for the retention volume , / W, is the molecular mass of the polymer fraction at the retention volume Vi and n is number of data points. Omnisec 5.12 as provided with the device can be used as a software.

[0076] The one or more waxes of general Formula I preferably has a melting point of from about 50 to about 85°C, more preferably from about 55 to about 80°C.

[0077] The one or more waxes is preferably used at about 2 to about 10 wt%, more preferably at about 3 to about 7 wt%, more particularly preferably at about 4 to about 6 wt%, based on the total weight of the oxidative drying intaglio ink.

[0078] Pigment

[0079] The oxidative drying intaglio inks of the invention may be white, transparent or colored inks allowing the preparation of white, transparent or colored security features. According to one embodiment, the oxidative drying intaglio inks of the invention are white inks. According to one embodiment, the oxidative drying intaglio inks of the invention are transparent inks. According to one embodiment, the oxidative drying intaglio inks of the invention are colored inks.

[0080] The oxidative drying intaglio inks of the invention optionally comprise one or more pigments. The pigments may be color constant or they may be optically variable, i.e. they may be selected from optically variable pigments, color constant pigments, color constant dyes and mixtures thereof, preferably selected from color constant organic pigments, color constant inorganic pigments and mixtures thereof.

[0081] In a preferred embodiment, the oxidative drying intaglio inks of the invention are color constant inks and may be white, transparent or colored inks. According to one embodiment, the oxidative drying intaglio inks of the invention are color constant white inks. According to one embodiment, the oxidative drying intaglio inks of the invention are color constant composition inks preferably comprising a) one or more dyes, and / or b) inorganic pigments, organic pigments or mixtures thereof. Dyes suitable for inks are known in the art and are preferably selected from the group comprising reactive dyes, direct dyes, anionic dyes, cationic dyes, acid dyes, basic dyes, food dyes, metal-complex dyes, solvent dyes and mixtures thereof. Typical examples of suitable dyes include without limitation coumarines, cyanines, oxazines, uranines, phtalocyanines, indolinocyanines, triphenylmethanes, naphtalocyanines, indonanaphtalo-metal dyes, anthraquinones, anthrapyridones, azo dyes, rhodamines, squarilium dyes, croconium dyes. Typical examples of dyes suitable for the present invention include without limitation C.l. Acid Yellow 1, 3, 5, 7, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 54, 59, 61, 70, 72, 73, 75, 76, 78, 79, 98, 99, 110, 111, 121, 127, 131, 135, 142, 157, 162, 164, 165, 194, 204, 236, 245; C.l. Direct Yellow 1 , 8, 11, 12, 24, 26, 27, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 106, 107, 110, 132, 142, 144; C.l. Basic Yellow 13, 28, 65; C.l. Reactive Yellow 1,2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25, 26, 27, 37, 42; C.l. Food Yellow 3, 4; C.l. Acid Orange 1, 3, 7, 10, 20, 76, 142, 144; C.l. Basic Orange 1, 2, 59; C.l.

[0082] Food Orange 2; C.l. Orange B; C.l. Acid Red 1, 4, 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 37, 42,

[0083] 51, 52, 57, 73, 75, 77, 80, 82, 85, 87, 88, 89, 92, 94, 97, 106, 111, 114, 115, 117, 118, 119, 129, 130, 131, 133, 134, 138, 143, 145, 154, 155, 158, 168, 180, 183, 184, 186, 194, 198,

[0084] 209, 211, 215, 219, 221, 249, 252, 254, 262, 265, 274, 282, 289, 303, 317, 320, 321, 322,

[0085] 357, 359; C.l. Basic Red 1,2, 14, 28; C.l. Direct Red 1, 2, 4, 9, 11, 13, 17, 20, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 80, 81, 83, 84, 89, 95, 99, 113, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230, 231, 253; C.l. Reactive Red 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 15,

[0086] 16, 17, 19, 20, 21, 22, 23, 24, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46,

[0087] 49, 50, 58, 59, 63, 64, 108, 180; C.l. Food Red 1, 7, 9, 14; C.l. Acid Blue 1, 7, 9, 15, 20, 22,

[0088] 23, 25, 27, 29, 40, 41, 43, 45, 54, 59, 60, 62, 72, 74, 78, 80, 82, 83, 90, 92, 93, 100, 102, 103,

[0089] 104, 112, 113, 117, 120, 126, 127, 129, 130, 131, 138, 140, 142, 143, 151, 154, 158, 161,

[0090] 166, 167, 168, 170, 171, 182, 183, 184, 187, 192, 193, 199, 203, 204, 205, 229, 234, 236,

[0091] 249, 254, 285; C.l. Basic Blue 1, 3, 5, 7, 8, 9, 11, 55, 81; C.l. Direct Blue 1,2, 6, 15, 22, 25,

[0092] 41, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 120, 123, 158, 160, 163, 165, 168, 192, 193,

[0093] 194, 195, 196, 199, 200, 201, 202, 203, 207, 225, 226, 236, 237, 246, 248, 249; C.l. Reactive Blue 1, 2, 3, 4, 5, 7, 8, 9, 13, 14, 15, 17, 18, 19, 20, 21, 25, 26, 27, 28, 29, 31, 32, 33, 34, 37, 38, 39, 40, 41, 43, 44, 46, 77; C.l. Food Blue 1, 2; C.l. Acid Green 1, 3, 5, 16, 26, 104; C.l. Basic Green 1, 4; C.l: Food Green 3; C.l. Acid Violet 9, 17, 90, 102, 121; C.l. Basic Violet 2, 3, 10, 11, 21; C.l. Acid Brown 101, 103, 165, 266, 268, 355, 357, 365, 384; C.l. Basic Brown 1; C.l. Acid Black 1, 2, 7, 24, 26, 29, 31, 48, 50, 51, 52, 58, 60, 62, 63, 64, 67, 72, 76, 77, 94,

[0094] 107, 108, 109, 110, 112, 115, 118, 119, 121, 122, 131, 132, 139, 140, 155, 156, 157, 158, 159, 191, 194; C.l. Direct Black 17, 19, 22, 32, 39, 51, 56, 62, 71, 74, 77, 94, 105, 106, 107,

[0095] 108, 112, 113, 117, 118, 132, 133, 146, 154, 168; C.l. Reactive Black 1, 3, 4, 5, 6, 8, 9, 10, 12, 13, 14, 18, 31; C.l. Food Black 2; C.l. Solvent Yellow 19, C.l. Solvent Orange 45, C.l. Solvent Red 8, C.l. Solvent Green 7, C.l. Solvent Blue 7, C.l. Solvent Black 7; C.l. Disperse Yellow 3, C.l. Disperse Red 4, 60, C.l. Disperse Blue 3, and metal azo dyes disclosed in US 5,074,914, US 5,997,622, US 6,001,161, JP 02-080470, JP 62-190272, JP 63-218766. Suitable dyes for the present invention may be infrared absorbing dyes or luminescent dyes. When present, the one or more dyes used in the oxidative drying intaglio ink of the invention are preferably present in a total amount from about 1 wt%, to about 20 wt%, the weight percents being based on the total weight of the oxidative drying intaglio ink.

[0096] Typical examples of organic and inorganic pigments include without limitation carbon black, C.l. Pigment Yellow 12, C.l. Pigment Yellow 42, C.l. Pigment Yellow 93, C.l. Pigment 109, C.l. Pigment Yellow 110, C.l. Pigment Yellow 147, C.l. Pigment Yellow 173, C.l. Pigment Orange 34, C.l. Pigment Orange 48, C.l. Pigment Orange 49, C.l. Pigment Orange 61 , C.l. Pigment Orange 71 , C.l. Pigment Orange 73, C.l. Pigment Red 9, C.l. Pigment Red 22, C.l. Pigment Red 23, C.l. Pigment Red 67, C.l. Pigment Red 122, C.l. Pigment Red 144, C.l. Pigment Red 146, C.l. Pigment Red 170, C.l. Pigment Red 177, C.l. Pigment Red 179, C.l. Pigment Red 185, C.l. Pigment Red 202, C.l. Pigment Red 224, C.l. Pigment Brown 6, C.l. Pigment Brown 7, C.l. Pigment Red 242, C.l. Pigment Red 254, C.l. Pigment Red 264, C.l. Pigment Brown 23, C.l. Pigment Blue 15, C.l. Pigment Blue 15:3, C.l. Pigment Blue 60, C.l. Pigment Violet 19, C.l. Pigment Violet 23, C.l. Pigment Violet 32, C.l. Pigment Violet 37, C.l. Pigment Green 7, C.l. Pigment Green 36, C.l. Pigment Black 7, C.l. Pigment Black 11 , Pigment Black 31 , Pigment Black 32, C. I. Pigment White 4, C.l Pigment White 6, C.l. Pigment White 7, C.l. Pigment White 21 , C. I. Pigment White 22, antimony yellow, lead chromate, lead chromate sulfate, lead molybdate, ultramarine blue, cobalt blue, manganese blue, chrome oxide green, hydrated chrome oxide green, cobalt green, cerium sulfide, cadmium sulfide, cadmium sulfoselenides, zinc ferrite, bismuth vanadate, Prussian blue, mixed metal oxides, azo, azomethine, methine, anthraquinone, phthalocyanine, perinone, perylene, diketopyrrolopyrrole, thioindigo, thiazinindigo, dioxazine, iminoisoindoline, iminoisoindolinone, quinacridone, flavanthrone, indanthrone, anthrapyrimidine and quinophthalone pigments. When present, the inorganic pigments, organic pigments or mixtures thereof described herein are preferably present in a total amount from about 0.1 wt% to about 45 wt%, the weight percents being based on the total weight of the oxidative drying intaglio ink.

[0097] For embodiments wherein the oxidative drying intaglio inks of the invention are transparent inks, said inks typically do not comprise any dyes or pigments such as those described herein. For embodiments wherein the oxidative drying intaglio inks of the invention are white, said inks comprise one or more pigments preferably selected from the group consisting of C.l. Pigment White 4, C.l Pigment White 6, C.l. Pigment White 7, C.l. Pigment White 21 and C. I. Pigment White 22.

[0098] According to one embodiment of the present invention, the oxidative drying intaglio inks of the invention are optically variable inks and comprise optically variable pigments or a mixture of different optically variable pigments. Optically variable inks may further comprise one or more color constant pigments. Optically variable inks preferably comprise optically variable pigments or a mixture of different optically variable pigments, wherein the optically variable pigments are preferably selected from the group consisting of thin film interference pigments, interference coated pigments, cholesteric liquid crystal pigments and mixtures thereof. When present, the optically variable pigments are preferably comprised in the oxidative drying intaglio ink of the invention in a total amount between about 5 wt% and about 40 wt% and more preferably in a total amount between about 10 wt% and about 35 wt%, the weight percents being based on the total weight of the oxidative drying intaglio ink.

[0099] Suitable thin film interference pigments exhibiting optically variable characteristics are known to those skilled in the art and disclosed in US 4,705,300; US 4,705,356; US 4,721 ,271 ; US 5,084,351 ; US 5,214,530; US 5,281 ,480; US 5,383,995; US 5,569,535, and US 5,571624. When at least a part of the optically variable pigments consists of thin film interference pigments, it is preferred that the thin film interference pigments comprise a Fabry-Perot reflector / dielectric / absorber multilayer structure and more preferably a Fabry-Perot absorber / dielectric / reflector / dielectric / absorber multilayer structure, wherein the absorber layers are partially transmitting and partially reflecting, the dielectric layers are transmitting and the reflective layer is reflecting the incoming light. Preferably, the reflector layer is selected from the group consisting of metals, metal alloys and combinations thereof, preferably selected from the group consisting of reflective metals, reflective metal alloys and combinations thereof and more preferably selected from the group consisting of aluminum (Al), chromium (Cr), nickel (Ni), and mixtures thereof and still more preferably aluminum (Al). Preferably, the dielectric layers are independently selected from the group consisting of magnesium fluoride (MgF2), silicium dioxide (SiO2) and mixtures thereof and more preferably magnesium fluoride (MgF2). Preferably, the absorber layers are independently selected from the group consisting of chromium (Cr), nickel (Ni), metallic alloys and mixtures thereof and more preferably chromium (Cr). When at least a part of the optically variable pigments consists of thin film interference pigments, it is particularly preferred that the thin film interference pigments comprise a Fabry-Perot absorber / dielectric / reflector / dielectric / absorber multilayer structure consisting of a Cr / MgF2 / AI / MgF2 / Cr multilayer structure.

[0100] Thin film interference pigments described herein are typically manufactured by vacuum deposition of the different required layers onto a web. After deposition of the desired number of layers, the stack of layers is removed from the web, either by dissolving a release layer in a suitable solvent, or by stripping the material from the web. The so-obtained material is then broken down to flakes which have to be further processed by grinding, milling or any suitable method. The resulting product consists of flat flakes with broken edges, irregular shapes and different aspect ratios.

[0101] Suitable interference coated pigments include without limitation structures consisting of a substrate selected from the group consisting of metallic cores such as titanium, silver, aluminum, copper, chromium, iron, germanium, molybdenum, tantalum or nickel coated with one or more layers made of metal oxides as well as structure consisting of a core made of synthetic or natural micas, other layered silicates (e.g. talc, kaolin and sericite), glasses (e.g. borosilicates), silicium dioxides (SiO2), aluminum oxides (AI2O3), aluminum oxides / hydroxides (boehmite), titanium oxides (TiO2), graphites and mixtures thereof coated with one or more layers made of metal oxides (e.g. titanium oxide, zirconium oxide, tin oxide, chromium oxide, nickel oxide, copper oxide, iron oxide and iron oxide / hydroxide). The structures described hereabove have been described for example in Chem. Rev. 99 (1999), G. Pfaff and P. Reynders, pages 1963-1981 and W02008 / 083894A2. Typical examples of these interference coated pigments include without limitation silicium oxide cores coated with one or more layers made of titanium oxide, tin oxide and / or iron oxide; natural or synthetic mica cores coated with one or more layers made of titanium oxide, silicium oxide and / or iron oxide, in particular mica cores coated with alternate layers made of silicium oxide and titanium oxide; borosilicate cores coated with one or more layers made of titanium oxide, silicium oxide and / or tin oxide; and titanium oxide cores coated with one or more layers made of iron oxide, iron oxide / hydroxide, chromium oxide, copper oxide, cerium oxide, aluminum oxide, silicium oxide, bismuth vanadate, nickel titanate, cobalt titanate and / or antimony-doped, fluorine-doped or indium- doped tin oxide; aluminum oxide cores coated with one or more layers made of titanium oxide and / or iron oxide.

[0102] Liquid crystals in the cholesteric phase exhibit a molecular order in the form of a helical superstructure perpendicular to the longitudinal axes of its molecules. The helical superstructure is at the origin of a periodic refractive index modulation throughout the liquid crystal material, which in turn results in a selective transmission I reflection of determined wavelengths of light (interference filter effect). Cholesteric liquid crystal polymers can be obtained by subjecting one or more cross-linkable substances (nematic compounds) with a chiral phase to alignment and orientation. The particular situation of the helical molecular arrangement leads to cholesteric liquid crystal materials exhibiting the property of reflecting a circularly polarized light component within a determined wavelength range. The pitch can be tuned in particular by varying selectable factors including the temperature and solvents concentration, by changing the nature of the chiral component(s) and the ratio of nematic and chiral compounds. Crosslinking under the influence of UV radiation freezes the pitch in a predetermined state by fixing the desired helical form so that the color of the resulting cholesteric liquid crystal materials is no longer depending on external factors such as the temperature. Cholesteric liquid crystal materials may then be shaped to cholesteric liquid crystal pigments by subsequently comminuting the polymer to the desired particle size. Examples of films and pigments made from cholesteric liquid crystal materials and their preparation are disclosed in US 5,211 ,877; US 5,362,315 and US 6,423,246 and in EP 1 213 338 A1 ; EP 1 046 692 A1 and EP 0 601 483 A1 , the respective disclosure of which is incorporated by reference herein.

[0103] The oxidative drying intaglio inks of the invention may further comprise one or more machine readable components preferably selected from the group consisting of magnetic materials, luminescent materials, electrically conductive materials, infrared-absorbing materials and mixtures thereof.

[0104] The oxidative drying intaglio inks of the invention may further comprise one or more forensic markers and / or one or more taggants.

[0105] The oxidative drying intaglio inks of the invention may further comprise one or more additives including without limitation compounds and materials which are used for adjusting physical, rheological and chemical parameters of the composition such as the viscosity, the consistency (e.g. anti-settling agents and plasticizers), the foaming properties (e.g. antifoaming agents and deaerators), UV stability (photostabilizers), adhesion properties, etc. Additives described herein may be present in the oxidative drying intaglio inks disclosed herein in amounts and in forms known in the art, including in the form of so-called nano-materials where at least one of the dimensions of the particles is in the range of 1 to 1000 nm.

[0106] Fillers

[0107] The oxidative drying intaglio inks of the invention comprise one or more fillers and / or extenders preferably selected from the group consisting of talcs, limestone, micas (e.g. muscovites), montmorillonites, bentonites, wollastonites, halloysites, calcined clays, China clays, carbonates (e.g. calcium carbonate, magnesium carbonate), silicates (e.g. magnesium silicate, aluminum silicate), vermiculites, amorphous silica (e.g. fumed silica, precipitated silica, silica flour), wood flours (sawdust), natural fibers, synthetic fibers (such as carbon fibers or carbon nanotubes) and mixtures thereof; preferably selected from the group consisting of talcs, micas, wollastonites, calcined clays, carbonates, amorphous silica and mixtures thereof. The one or more fillers or extenders are preferably present in a total amount from about 10 wt% to about 60 wt%, more preferably from about 25 wt% to about 55 wt%, even more preferably from about 30 wt% to about 50 wt%, the weight percents being based on the total weight of the oxidative drying intaglio ink.

[0108] In a preferred embodiment, the ink of the invention comprises talc and calcium carbonate, preferably about 1 to about 5 wt% talc, more preferably about 2 wt% talc, and preferably about 20 to about 50 wt% calcium carbonate, more preferably about 42 wt% calcium carbonate.

[0109] Solvent

[0110] The oxidative drying intaglio inks of the invention comprise one or more solvents. Such solvents may be of vegetable or mineral origin. Mineral solvents are usually derived from petroleum and preferred examples include without limitation low aromatic or non-aromatic linear or branched hydrocarbons preferably having a boiling point at 760 mm Hg of more than 140°C, preferably more than 160°C, and even more preferably more than 180°C. Preferably, the low aromatic or non-aromatic hydrocarbon solvents are linear alkanes having more than 10 carbon atoms, for example mineral oil, more preferable n-undecane. Examples of solvents of vegetal origin include high-boiling point esters obtained from the condensation of saturated or unsaturated linear fatty acids, comprising between 10 and 18 carbon atoms obtained from e.g. soybean oil, coconut oil, palm oil, olive oil, linseed oil, cottonseed oil, safflower oil, sunflower oil, tung oil, tar oil, rapeseed oil, dehydrated castor oil, sesame oil and the like, and a linear or branched monoalcohol bearing between 2 and 8 carbon atoms. Such fatty acids esters are liquid at room temperature and preferably have a boiling point at 760 mmHg of more than 240°C, more preferably more than 260°C, and even more preferably more than 280°C, making them essentially non-volatile and odorless under the required printing conditions. Examples include isopropyl laurate (boiling point 280°C), 2-ethylhexyl oleate (b.p. > 300°C), butyl oleate (b.p. >300°C), 2-ethylhexyl stearate (b.p. > 300°C) and 2-ethylhexyl laurate (b.p. >300°C). The total amount of the one or more solvents in the oxidatively drying intaglio ink of the invention is preferably between about 1 wt% and 25 wt%, preferably between about 2 wt% and 20 wt%, and more preferably between about 5 wt% and 15 wt%.

[0111] In a preferred embodiment, the solvent comprises mineral oil.

[0112] Other optional ingredients

[0113] The oxidative drying intaglio inks of the invention may further comprise one or more surfactants, in particular hydrophilic macromolecular surfactants such as those described e.g. in EP 0 340 163 B1. The role of the optional surfactants is to help wiping off the excess of ink present on the printing cylinder just before contacting said printing cylinder with the substrate. This process of wiping off the excess of ink is part of any high-speed industrial intaglio printing process and is carried out using a tissue or a paper roll (“calico”) or a polymer wiping cylinder and a cleansing water-based solution (“wiping solution”). In this case, the optional surfactants are used to emulsify the excess of ink in the cleansing solution. Said surfactants may be nonionic, anionic or cationic as well as zwitterionic ones. In the case of hydrophilic macromolecular surfactants, the functional groups are for example carboxylic or sulfonic acid groups, hydroxyl groups, ether groups or primary, secondary, tertiary or quaternary amino groups. The acid groups may be neutralized with amines, alcanolamines or preferably inorganic bases, or combinations thereof. Primary, secondary and tertiary amino groups may be neutralized with inorganic or organic acids such as sulfonic acids, formic acid, acetic acid, trifluoroacetic acid and others. Particularly preferred are anionic macromolecular surfactants (AMS), such as those described in EP 2 014 729 A1 .

[0114] Viscosity

[0115] Preferably the oxidative drying intaglio ink of the invention has a viscosity in the range of about 3 to about 60 Pa s at 40°C and 1000 s-1, more preferably 3 to 16 Pa s, particularly preferably 3 to 11 Pa s, when measured using a Haake Roto Visco RV1 rotational rheometer, using a cone plate of 20 mm diameter and a 0.5° geometry.

[0116] Printing processes

[0117] In one aspect, the invention provides a process for producing a security feature on a substrate by an intaglio printing process, said process comprising the steps:

[0118] A) inking an intaglio engraved printing plate with an oxidative drying intaglio ink, said oxidative drying intaglio ink comprising:

[0119] (1) one or more oxidative drying varnishes;

[0120] (2) one or more driers; and

[0121] (3) one or more waxes of general Formula I: wherein a is an integer from 6 to 24, b is an integer from 2 to 6, c is an integer from 2 to 6, m is 1 to 6, n is 8 to 15, and the CH2groups designated with an asterisk (*) and / or a dagger (t) may have one hydrogen replaced with a Ci.2-alkyl substituent;

[0122] (4) one or more fillers and extenders; and

[0123] (5) one or more solvents;

[0124] B) removing excess oxidative drying intaglio ink;

[0125] C) transferring the oxidative drying intaglio ink in the form of the security feature on the substrate; and

[0126] D) drying the oxidative drying intaglio ink in the presence of air so as to form the security feature.

[0127] In one embodiment, wiping in step B) is carried out by wiping using a paper or a tissue wiping system or using a polymeric wiping cylinder and cleaning said polymeric wiping cylinder with an alkaline aqueous wiping solution in combination with one or more mechanical means. The wiping cylinder is typically made of polymeric material, in particular PVC or rubber. The aqueous alkaline wiping solution typically comprises between about 0.3 wt% and about 1.2 wt% (weight percent) of a strong base, such as e.g. sodium hydroxide NaOH, and between about 0.3 wt% and about 1 wt% (weight percent) of a surfactant, such as e.g. sulphonated castor oil (SCO), the weight percents being based on the total weight of the alkaline aqueous wiping solution.

[0128] The oxidative drying intaglio inks of the invention are suitable for the production of security features on a substrate using intaglio printing processes. Examples of substrates include papers or other fibrous materials (including woven and non-woven fibrous materials), such as cellulose, paper-containing materials, glasses, metals, ceramics, plastics and polymers, metallized plastics or polymers, composite materials and mixtures or combinations of two or more thereof. Typical paper, paper-like or other fibrous materials are made from a variety of fibers including without limitation abaca, cotton, linen, wood pulp, and blends thereof. As is well known to those skilled in the art, cotton and cotton / linen blends are preferred for banknotes, while wood pulp is commonly used in non-banknote value documents. Typical examples of plastics and polymers include polyolefins such as polyethylene (PE) and polypropylene (PP) including biaxially oriented polypropylene (BOPP), polyamides (PA), polyesters such as polyethylene terephthalate) (PET), polyethylene terephthalate glycol- modified (PETG) including polyethylene glycol-co-1 ,4-cyclohexanedimethanol terephthalate), poly(1 ,4-butylene terephthalate) (PBT), poly(ethylene 2,6-naphthoate) (PEN) and polyvinylchlorides (PVC). Spunbond olefin fibers such as those sold under the trademark Tyvek® may also be used as substrate. Typical examples of metalized plastics or polymers include the plastic or polymer materials described hereabove having a metal disposed continuously or discontinuously on their surface. Typical example of metals include without limitation aluminum (Al), chromium (Or), copper (Cu), gold (Au), silver (Ag), alloys thereof and combinations of two or more of the aforementioned metals. The metallization of the plastic or polymer materials described hereabove may be done by an electrodeposition process, a high- vacuum coating process or by a sputtering process. Typical examples of composite materials include without limitation multilayer structures or laminates of paper and at least one plastic or polymer material such as those described hereabove as well as plastic and / or polymer fibers incorporated in a paper-like or fibrous material such as those described hereabove. Of course, the substrate can comprise further additives that are known to the skilled person, such as fillers, sizing agents, Whiteners, processing aids, reinforcing or wet strengthening agents, etc. With the aim of further increasing the security level and the resistance against counterfeiting and illegal reproduction of value documents, the substrate may contain watermarks, security threads, fibers, planchettes, luminescent compounds, windows, foils, decals, coatings and combinations thereof. The invention relates as well to value documents comprising one or more security features made with the oxidative drying intaglio ink of the invention. Preferably, the value document is selected from banknotes, deeds, tickets, checks, vouchers, fiscal stamps, agreements, identity documents such as passports, identity cards, visas, driving licenses, bank cards, credit cards, transactions cards, access documents, and cards, entrance tickets, public transportation tickets, academic diploma, and academic titles. More preferably the value document is a banknote.

[0129] The security document may further comprise one or more additional layers or coatings either below or on top of the security feature made of the oxidative drying intaglio ink of the invention. Should the adhesion between the substrate and the security feature be insufficient, for example, due to the substrate material, a surface unevenness or a surface inhomogeneity, an additional layer, coating or a primer between the substrate and the security feature might be applied as known for those skilled in the art.

[0130] With the aim of increasing the durability through resistance against soiling or chemicals and the cleanliness and thus the circulation lifetime of security documents, one or more protective layers may be applied on top of the one or more security features. When present, the one or more protective layers are typically made of protective varnishes which may be transparent or slightly colored or tinted and may be more or less glossy. Protective varnishes may be radiation curable compositions, thermal drying compositions or any combination thereof. Preferably, the one or more protective layers are made of radiation curable, more preferably UV-Vis curable compositions.

[0131] Process of manufacture

[0132] The invention also relates to processes for producing the oxidative drying intaglio inks of the invention. The oxidative drying intaglio inks of the invention may be prepared by mixing all the ingredients except the one or more driers and dispersing or grinding them using for example a three-roll mill and subsequently adding and mixing the one or more driers.

[0133] Preferred embodiments of the invention

[0134] 1. An oxidative drying intaglio ink, comprising:

[0135] (1) one or more oxidative drying varnishes;

[0136] (2) one or more driers;

[0137] (3) one or more waxes of general Formula I: wherein a is an integer from 6 to 24, b is an integer from 2 to 6, c is an integer from 2 to 6, m is 1 to 6, n is 8 to 15, and the CH2groups designated with an asterisk (*) and / or a dagger (t) may have one hydrogen replaced with a Ci.2-alkyl substituent;

[0138] (4) one or more fillers and extenders; and

[0139] (5) one or more solvents.

[0140] 2. The oxidative drying intaglio ink of embodiment 1 , wherein a is an integer from 6 to 22, preferably 10 to 20, more preferably a is 16.

[0141] 3. The oxidative drying intaglio ink of embodiment 1 or 2, wherein b is an integer from 2 to 4, preferably 2 to 3, more preferably b is 2 or 3.

[0142] 4. The oxidative drying intaglio ink of embodiment 1 , 2 or 3, wherein b is 2, and one of the carbons designated with an asterisk (*) in each C2linkage bears a methyl group.

[0143] 5. The oxidative drying intaglio ink of any one preceding embodiment, wherein c is an integer from 2 to 4, preferably 2 to 3, more preferably c is 2 or 3.

[0144] 6. The oxidative drying intaglio ink of any one preceding embodiment, wherein c is 2, and one of the carbons designated with a dagger (t) in each C2linkage bears a methyl group.

[0145] 7. The oxidative drying intaglio ink of any one preceding embodiment, wherein b and c are both 2, or b and c are both 3.

[0146] 8. The oxidative drying intaglio ink of any one preceding embodiment, wherein b and c are both 2, and one of the carbons designated with an asterisk (*) in each C2linkage bears a methyl group, and one of the carbons designated with a dagger (t) in each C2linkage bears a methyl group. 9. The oxidative drying intaglio ink of any one preceding embodiment, wherein b and c are both 3, and none of the carbons designated with an asterisk (*) or designated with a dagger (t) bears an alkyl group.

[0147] 10. The oxidative drying intaglio ink of any one preceding embodiment, wherein m is about 1 .5 to about 4, preferably m is about 1.75 to about 3.5, more preferably m is about 1 .8 to about 2.9.

[0148] 11 . The oxidative drying intaglio ink of any one preceding embodiment, wherein n is about 8 to about 12, preferably n is about 8.5 to about 11 , more preferably n is about 9.5 to about 10.7.

[0149] 12. The oxidative drying intaglio ink of any one preceding embodiment, wherein m is about 1 .8 to about 2.9 and n is about 9.5 to about 10.7.

[0150] 13. The oxidative drying intaglio ink of any one preceding embodiment, wherein m is about 1.5 to about 4, preferably m is about 1.75 to about 3.5 and n is about 8 to about 12, preferably n is about 8.5 to about 11.

[0151] 14. The oxidative drying intaglio ink of any one preceding embodiment, wherein a is 16, b and c are 2, one of the carbons designated with an asterisk (*) in each C2linkage and one of the carbons designated with a dagger (t) in each C2linkage bear a methyl group, n is about 9 to about 10, and m is about 2 to about 2.2.

[0152] 15. The oxidative drying intaglio ink of any one preceding embodiment, wherein a is 16, b and c are 3, n is about 10 to about 11 , and m is about 1 .8 to about 2.1.

[0153] 16. The oxidative drying intaglio ink of any one preceding embodiment, wherein a is 16, b and c are 2, n is about 9.8 to about 10, and m is about 2.6 to about 3.

[0154] 17. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more waxes of general Formula I has a number average molecular weight of from about

[0155] 3.500 g / mol eq PS to about 6,000 g / mol eq PS, preferably from about 3,900 g / mol eq PS to about 5,000 g / mol eq PS, more preferably from about 4,000 g / mol eq PS to about

[0156] 4.500 g / mol eq PS. 18. The oxidative drying intaglio ink of embodiment 17, wherein the number average molecular weight of the one or more waxes is determined by GPC (gel permeation chromatography) according to OECD test method 118.

[0157] 19. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more waxes of general Formula I has a melting point of from about 50 to about 85°C, more preferably from about 55 to about 80°C.

[0158] 20. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more waxes is present at about 2 to about 10 wt%, preferably at about 3 to about 7 wt%, more preferably at about 4 to about 6 wt%, based on the total weight of the oxidative drying intaglio ink.

[0159] 21 . The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish is present in an amount from at or about 10 to at or about 90 wt%, more preferably at or about 20 to at or about 60 wt%, when the ink does not comprise pigments, and from about 5 to about 30 wt%, more preferably about 10 to about 20 wt% when the ink comprises pigment, the weight percents being based on the total weight of the oxidative drying intaglio ink.

[0160] 22. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish comprises unsaturated fatty acid residues.

[0161] 23. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish comprises an acid-modified resin.

[0162] 24. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish is selected from the group consisting of alkyd resins, vinyl polymers, polyurethane resins, polyesters, hyperbranched resins, rosin-modified maleic resins, rosin-modified phenol resins, rosin esters, petroleum resin-modified rosin esters, petroleum resin-modified alkyd resins, alkyd resin-modified rosin / phenol resins, alkyd resin-modified rosin esters, acrylic-modified rosin / phenol resins, acrylic-modified rosin esters, urethane-modified rosin / phenol resins, urethane-modified rosin esters, urethane- modified alkyd resins, epoxy-modified rosin / phenol resins, epoxy-modified alkyd resins, terpene resins, nitrocellulose resins, polyolefins, polyamides, acrylic resins and combinations or mixtures thereof. 11

[0163] 25. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish comprises saturated and unsaturated fatty acid compounds obtained from natural and / or artificial sources.

[0164] 26. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish comprises saturated and unsaturated fatty acid compounds obtained from animal fat, butter fat, fish oil, lard, liver fats, tuna fish oil, sperm whale oil and / or tallow oil.

[0165] 27. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish comprises saturated and unsaturated fatty acid compounds obtained from vegetable oils selected from those obtained from bitter gourd, borage, calendula, canola, castor, China wood, coconut, conifer seed, corn, cottonseed, dehydrated castor, flaxseed, grape seed, Jacaranda mimosifolia seed, linseed oil, palm, palm kernel, peanut, pomegranate seed, rapeseed, safflower, snake gourd, soya (bean), sunflower, tall, tung, wheat germ and mixtures thereof.

[0166] 28. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish comprises saturated and unsaturated fatty acid compounds obtained from myristoleic acid (C14H26O2, CAS No 544-64-9), palmitoleic acid (C16H30O2, CAS No 373-49-9), oleic acid (C18H34O2, CAS No 112-80-1), a-eleostearic acid (C18H30O2, CAS No 506-23-0), licanic acid (CI8H28O3, CAS No 623-99-4), linoleic acid (C18H32O2, CAS No 60-33-3), linolenic acid (C18H30O2, CAS No 463-40-1), stearidonic acid (CI8H28O2, CAS No 20290-75-9), arachidonic acid (C20H32O2, CAS No 506-32-1), ricinoleic acid (C18H34O3, CAS No 141-22-0), erucic acid (C22H42O2, CAS No 112-86-7), gadoleic acid (C20H38O2, CAS No 29204-02-2), clupanodonic acid (C22H34O2, CAS No 24880-45-3), nisinic acid (C24H36O2, CAS No 68378-49-4) and mixtures thereof.

[0167] 29. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish is a polyester, preferably a partially neutralized acidified polyester.

[0168] 30. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish is a partially neutralized acidified polyester which is a condensation product of conjugated fatty acids, one or more diacids, and one or more polyols. 31 . The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish is a product of conjugated sunflower oil fatty acids, isophthalic acid, tetrahydrophthalic anhydride, trimethylolpropane and pentaerythritol.

[0169] 32. The oxidative drying intaglio ink of any one preceding embodiment, wherein the at least one oxidative drying varnish is a product of conjugated sunflower oil fatty acids at about 32.8 wt%, isophthalic acid at about 13.1 wt%, tetrahydrophthalic anhydride at about 12.8 wt%, trimethylolpropane at about 8.6 wt%, and pentaerythritol at about 7.4 wt%, neutralized with potassium hydroxide and dodecyl benzenesulfonic acid salt of 2-amino- propane, the weight percents being based on the total weight of the oxidative drying varnish.

[0170] 33. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more driers is selected from inorganic or organic salts of metal(s), metallic soaps of organic acids, metal complexes and metal complex salts.

[0171] 34. The oxidative drying intaglio ink of embodiment 33, wherein the salts of metal(s) are selected from salts containing cobalt, calcium, copper, zinc, iron, zirconium, manganese, barium, zinc, strontium, lithium, vanadium and potassium as the cation(s); and halides, nitrates, sulphates, carboxylates like acetates, ethylhexanoates, octanoates and naphtenates or acetoacetonates as the anion(s).

[0172] 35. The oxidative drying intaglio ink of embodiment 33 or 34, wherein the salts of metal(s) are selected from ethylhexanoates of cobalt, manganese and zirconium.

[0173] 36. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more driers is a mixture of manganese(ll) salts and cobalt(ll) salts, particularly a mixture of 2-ethylhexanoate salts of Mn++and Co++.

[0174] 37. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more driers is present in a total amount from at or about 0.01 wt% to about 10 wt%, preferably in a total amount from at or about 0.1 wt% to about 5 wt%, the weight percents being based on the total weight of the oxidative drying intaglio ink.

[0175] 38. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more driers is a mixture of 2-ethylhexanoate salts of Mn++and Co++, used at or about 0.1 to at or about 5 wt%, based on the total weight of the oxidative dying intaglio ink. 39. The oxidative drying intaglio ink of any one preceding embodiment, wherein the ink is white, transparent or colored.

[0176] 40. The oxidative drying intaglio ink of any one preceding embodiment, which additionally comprises one or more pigments, selected from color constant pigments and dyes, optically variable pigments, and mixtures thereof.

[0177] 41 . The oxidative drying intaglio ink of any one preceding embodiment, comprising:

[0178] (1) about 10 to about 80 wt%, preferably about 15 to about 35 wt% of one or more oxidative drying varnishes;

[0179] (2) about 0.01 wt% to about 10 wt%, preferably about 0.1 wt% to about 5 wt% of one or more driers;

[0180] (3) about 2 to about 10 wt%, preferably about 3 to about 7 wt%, more preferably about 4 to about 6 wt% of one or more waxes of general Formula I, wherein the weight percents are based on the total weight of the oxidative drying intaglio ink.

[0181] 42. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more fillers and / or extenders is selected from the group consisting of talcs, limestone, micas (e.g. muscovites), montmorillonites, bentonites, wollastonites, halloysites, calcined clays, China clays, carbonates (e.g. calcium carbonate, magnesium carbonate), silicates (e.g. magnesium silicate, aluminum silicate), vermiculites, amorphous silica (e.g. fumed silica, precipitated silica, silica flour), wood flours (sawdust), natural fibers, synthetic fibers (such as carbon fibers or carbon nanotubes) and mixtures thereof.

[0182] 43. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more fillers and / or extenders is selected from the group consisting of talcs, micas, wollastonites, calcined clays, carbonates, amorphous silica and mixtures thereof.

[0183] 44. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more fillers or extenders are preferably present in a total amount from about 10 wt% to about 60 wt%, more preferably from about 25 wt% to about 55 wt%, even more preferably from about 30 wt% to about 50 wt%, the weight percents being based on the total weight of the oxidative drying intaglio ink. 45. The oxidative drying intaglio ink of any one preceding embodiment, comprising talc and calcium carbonate, preferably about 1 to about 5 wt% talc, more preferably about 2 wt% talc, and preferably about 20 to about 50 wt% calcium carbonate, more preferably about 42 wt% calcium carbonate.

[0184] 46. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more solvents is of vegetable or mineral origin.

[0185] 47. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more solvents is selected from low aromatic or non-aromatic linear or branched hydrocarbons having a boiling point at 760 mmHg of more than 140°C, preferably more than 160°C, and even more preferably more than 180°C.

[0186] 48. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more solvents is selected from alkanes having more than 10 carbon atoms.

[0187] 49. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more solvents is selected from high-boiling point esters obtained from the condensation of saturated or unsaturated linear fatty acids, comprising between 10 and 18 carbon atoms obtained from soybean oil, coconut oil, palm oil, olive oil, linseed oil, cottonseed oil, safflower oil, sunflower oil, tung oil, tar oil, rapeseed oil, dehydrated castor oil, or sesame oil, and a linear or branched monoalcohol bearing between 2 and 8 carbon atoms.

[0188] 50. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more solvents is selected from fatty acids esters which are liquid at room temperature and have a boiling point at 760 mmHg of more than 240°C, more preferably more than 260°C, and even more preferably more than 280°C.

[0189] 51 . The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more solvents is selected from isopropyl laurate, 2-ethylhexyl oleate, butyl oleate (b.p. >300°C), 2-ethylhexyl stearate (b.p. > 300°C) and 2-ethylhexyl laurate (b.p. >300°C).

[0190] 52. The oxidative drying intaglio ink of any one preceding embodiment, wherein the one or more solvents is present at between about 1 wt% and 25 wt%, preferably between about 2 wt% and 20 wt%, and more preferably between about 5 wt% and 15 wt%. 53. A security document printed using the oxidative drying intaglio ink of any one preceding embodiment.

[0191] Examples

[0192] The invention is illustrated with the following non-limiting examples.

[0193] The ingredients used in comparative inks C1-C6 and inventive inks E1-E3 are listed in Table

[0194] 1.

[0195] The waxes used in comparative inks C1-C6 and inventive inks E1-E3 are detailed in Table 2.

[0196] 1DSC ASTM D 938

[0197] 2ASTM D 664

[0198] 3ISO3681

[0199] 4ASTM D 4274

[0200] 5calculated from min. and max. chain length

[0201] Molecular weights of waxes of general Formula I

[0202] The number average molecular weights (Mn) of the waxes of general Formula I were determined by GPC (gel permeation chromatography) according to OECD test method 118. A Malvern Viskotek GPCmax was used. The device was equipped with an isocratic pump, a degasser, an autosampler and a differential refractometer. A calibration curve [log(molecular mass) vs f(retention volume)] was established using six polystyrene standards (with molecular masses ranging from 472 to 512,000 g / mol) and n-hexylbenzene being used for as the standard for the smallest molecular mass (M = 162 g / mol). The equation of the calibration curve obtained from the chromatograms was as follows: y = -0.3218x + 10.25 (R2= 0.9977) with y = log(molecular mass) and x = retention volume in ml.

[0203] Two columns Viskotek TM4008L (column length 30.0 cm, internal diameter 8.0 mm) were coupled in series. The stationary phase was a styrene-divinylbenzene copolymer with a particle size of 6 pm and a maximum pore size of 3000 A. During the measurement, the temperature was fixed at 35°C. The analyzed samples contained 10 mg / mL of wax of general Formula I dissolved in THF, and were injected at a rate of 1 mL / min. The molecular mass of the wax of general Formula I was calculated from the chromatogram as a polystyrene- equivalent number average molecular weight (PS eq Mn) using the following formula: where H, is the level of the detector signal (differential refractometer) from the baseline for the retention volume V, / W, is the molecular mass of the polymer fraction at the retention volume Vi and n is number of data points. Omnisec 5.12, as provided with the device, was used as software.

[0204] Preparation of oxidative drying intaglio inks (E1 - E3 and C1 - C6)

[0205] Inks according to the invention are designated with an “E” (E1-E3) and comparative inks are designated with a “C” (C1-C6).

[0206] Oxidative drying intaglio inks (E1 - E3 and C1 - C6, see Table 3) were prepared from three compositions: a black pigment paste (see Table 3), a transparent white composition (TW1 - TW9, see Table 4) and a blend of drying agents (see Table 5). With the exception of ink C1 (comparative ink devoid of wax), all inks comprised a wax. When present, the wax (W1-W8) was added during the production of the transparent white compositions (TW1-TW9) as described in Table 4.

[0207] The blend of drying agents was added to the dispersed mixture of the transparent white compositions (TW1 - TW9) and the black pigment paste, to generate the final intaglio inks (E1-E3 and C1-C6), in the proportions listed in Table 6. The final compositions of the inks are shown in Table 7.

[0208] To prepare the pigment paste, the ingredients listed in Table 3 were mixed at room temperature using a Speedmixer for 3 minutes at 2500 rpm. They were then ground on a Buehler three-roll mill in three passes with pressures of 5, 11 and 11 bars, so at to produce the black pigment paste.

[0209] The transparent whites (TW1 - TW9) were prepared by mixing the ingredients listed in Table 4 using a Speedmixer (3 minutes at 2,500 rpm), then ground on a Buehler three-roll mill in three passes with pressures of 5, 11 , and 11 bars.

[0210]

[0211] The drying mixture was prepared by mixing the ingredients listed in Table 5 at room temperature for ten minutes.

[0212] The oxidative drying intaglio inks (E1-E3 and C1-C6) described in Table 7 were prepared according to the following steps:

[0213] The black pigment paste and the respective transparent white compositions (TW1-TW9) were mixed using a Speedmixer at room temperature for 90 seconds at 2,500 rpm.

[0214] The drying mixture was added to the dispersed pastes obtained in the previous step and further mixed with the Speedmixer for 3 minutes at 2,500 rpm. The mixing proportions for all inks are listed in Table 6.

[0215] The viscosities of the oxidative drying intaglio inks (E1-E3 and C1-C6) were measured using a Haake Roto Visco RV1 rotational rheometer, using a cone plate of 20 mm diameter and a 0.5° geometry, at a shear rate of 1 ,000 s-1and a temperature of 40°C. The results are reported in Table 7.

[0216]

[0217]

[0218] Preparation of printed samples

[0219] The oxidative drying intaglio inks (E1-E3 and C1-C6) were applied by hand using an Ormag intaglio proof-press. An intaglio engraved printing plate was used to prepare the intaglio printed samples. The plate comprised a set of “U”-shaped engravings of various depths (from about 20 pm to about 100 pm) and widths (from about 60 pm to about 500 pm) so as to mimic an intaglio printed feature on a banknote. The image comprised the following regions:

[0220] • a “face” region that had thin and shallow engraving lines. These lines will be easier to dry and less incline to generate set-off;

[0221] • a “hat” portion that had thicker and deeper engraving lines. These lines will be more difficult to dry and are likely to generate higher set-off, and

[0222] • a guilloche portion that had very thick and deep lines. These lines require high drying performance in order to avoid or reduce set-off.

[0223] The engraved printing plate was inked with each of the oxidative drying intaglio inks (E1-E3 and C1-C6) using a polymer hand-roller (Step A). The plate had a printing plate temperature of about 65°C.

[0224] Excess ink was manually wiped off the printing plate with paper, leaving ink only in the engravings (Step B).

[0225] The plate was used to apply the oxidative drying intaglio inks (E1-E3 and C1-C6) on a blank sheet of cotton fiduciary paper (Louisenthal) (Step C).

[0226] The inks were dried in air (Step D). For each example and comparative example, ten samples were printed.

[0227] Assessment of set-off and counterpressure resistance Set-off

[0228] Immediately after the printing process, five printed samples carrying the image described above were stacked to form a pile with an interleaved blank sheet between each print. The pile was placed between two glass plates and was kept for 24 hours at 22°C and 50% RH under 3 kg pressure to mimic a pile of 1 ,500 prints. The prints were then removed from the pile and the interleaved blank sheet corresponding to each print was assessed in terms of setoff characteristics according to the scale shown in Table 8: The inks were evaluated using the image described above, that had thin and shallow engraving lines that are easy to dry and will be less inclined to generate set-off, as well as thicker and deeper engraving lines that are more difficult to dry and are likely to generate higher set-off, and finally, portions with very thick and deep lines that require high drying performance from the ink in to avoid or reduce set-off. Such a mosaic of thin and thick, shallow and deep engraving lines represents the blend of engraving lines to be found on banknotes as well as on other documents of value such as passports or stamps. For each example and comparative example, the five prints were independently assessed for set-off, the values presented in Table 9 are the average of the five prints. A value of 3.5 or greater is deemed acceptable.

[0229] Counterpressure

[0230] For all examples (E1-E3) and comparative examples (C1-C6), the remaining printed samples were left in the dark for 24 hours at room temperature to dry, then a piece of blank substrate was placed on the printed side of each of them and the two sheets were submitted to a pressure of 800-1000 bar at 65°C using the ORMAG Intaglio Proof Press.

[0231] To precisely determine the counterpressure value, a Fujifilm Prescale HS film (having a sensitivity between 50 and 130 MPa) was pressed at 25°C in the ORMAG Intaglio Proof Press. The optical density of the film (ODmax) was measured at ten randomly chosen points using a Techkon SpectroDens densitometer (illuminant: D65 at 10°, reference white: unused film, density filter: ISO E, CMYK mode, polarizing filter: auto). An average value was calculated and compared with the scale provided by Fujifilm. The calculated average value of ODmax corresponded to a pressure of about 92 MPa. Assuming an error margin of ±10%, the pressure was finally calculated to be about 83-101 MPa, i.e. about 800-1000 bar.

[0232] The substrate carrying the printed and dried image and the piece of blank substrate were separated and counterpressure was independently assessed for five prints of each example (E1-E3) and comparative example (C1-C6). Counterpressure test results were assessed according to the 1-5 scale shown in Table 8: Results were averaged for the five prints of each example (E1-E3) and comparative example (C1-C6) and reported in Table 9. A value of 3.5 or greater is deemed acceptable. Hence, to be considered acceptable, the tested oxidatively drying intaglio inks must exhibit a value of at least 3.5 in both the set-off and the counterpressure tests. The oxidatively drying intaglio inks C1 (no wax) and C5 (paraffin 80°C) are insufficient in both the set-off and the counterpressure tests. The inks C2 (carnauba), C3 (rice bran wax) and C4 (paraffin 60°C) exhibit insufficient set-off test results. Ink C6 (wax = C18 dioic acid, dimethyl ester) exhibits insufficient counterpressure test results. In contrast, oxidatively drying intaglio inks E1-E3 according to the invention, exhibit good results in both tests, which means that substrates printed with inks E1-E3 can be stacked in piles after an intaglio printing run without problematic set-off and that they can withstand the very high pressure of a second intaglio printing run (i.e. to print the back side of the substrate) after a reasonable drying time.

Claims

1. Claims1. An oxidative drying intaglio ink, comprising:(1) one or more oxidative drying varnishes;(2) one or more driers;(3) one or more waxes of general Formula I:wherein a is an integer from 6 to 24, b is an integer from 2 to 6, c is an integer from 2 to 6, m is 1 to 6, n is 8 to 15, and the CH2groups designated with an asterisk (*) and / or a dagger (t) may have one hydrogen replaced with a Ci_2-alkyl substituent; and(4) one or more fillers and extenders; and(5) one or more solvents.

2. The oxidative drying intaglio ink of claim 1 , wherein a is an integer from 6 to 22, preferably 10 to 20, more preferably a is 16.

3. The oxidative drying intaglio ink of claim 1 or 2, wherein b is an integer from 2 to 4, preferably 2 to 3, more preferably b is 2 or 3.

4. The oxidative drying intaglio ink of claim 1 , 2 or 3, wherein b is 2, and one of the carbons designated with an asterisk (*) in each C2linkage bears a methyl group.

5. The oxidative drying intaglio ink of any one preceding claim, wherein c is an integer from 2 to 4, preferably 2 to 3, more preferably c is 2 or 3.

6. The oxidative drying intaglio ink of any one preceding claim, wherein c is 2, and one of the carbons designated with a dagger (t) in each C2linkage bears a methyl group.

7. The oxidative drying intaglio ink of any one preceding claim, wherein b and c are both 2, or b and c are both 3.

8. The oxidative drying intaglio ink of any one preceding claim, wherein b and c are both 2, and one of the carbons designated with an asterisk (*) in each C2linkage bears amethyl group, and one of the carbons designated with a dagger (t) in each C2linkage bears a methyl group.

9. The oxidative drying intaglio ink of any one preceding claim, wherein b and c are both 3, and none of the carbons designated with an asterisk (*) or designated with a dagger (t) bears an alkyl group.

10. The oxidative drying intaglio ink of any one preceding claim, wherein m is about 1 .5 to about 4, preferably m is about 1.75 to about 3.5.

11. The oxidative drying intaglio ink of any one preceding claim, wherein n is about 8 to about 12, preferably n is about 8.5 to about 11.

12. The oxidative drying intaglio ink of any one preceding claim, wherein m is about 1 .5 to about 4, preferably m is about 1 .75 to about 3.5 and n is about 8 to about 12, preferably n is about 8.5 to about 11 .

13. The oxidative drying intaglio ink of any one preceding claim, wherein a is 16, b and c are 2, one of the carbons designated with an asterisk (*) in each C2linkage and one of the carbons designated with a dagger (t) in each C2linkage bear a methyl group, n is about 9 to about 10, and m is about 2 to about 2.2.

14. The oxidative drying intaglio ink of any one preceding claim, wherein a is 16, b and c are 3, n is about 10 to about 11 , and m is about 1.8 to about 2.1.

15. The oxidative drying intaglio ink of any one preceding claim, wherein a is 16, b and c are 2, n is about 9.8 to about 10, and m is about 2.6 to about 3.

16. The oxidative drying intaglio ink of any one preceding claim, wherein the one or more waxes of general Formula I has a melting point of from about 50 to about 85°C, more preferably from about 55 to about 80°C.

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