UV-VIS radiation-curable security ink for manufacturing dichroic security features

Abstract

The present invention provides a UV-Vis radiation-curable security ink for manufacturing security features for securing value documents, wherein the security features appear blue when viewed under transmitted light and metallic yellow when viewed under incident light. The UV-Vis radiation-curable security ink comprises a silver nanoplatelet comprising a cationic-curable or hybrid-curable ink vehicle and a surface stabilizer of the following general formula (I): (I) In the above formula, The residue RA is a C2-C4 alkyl group substituted with a hydroxyl group; Residue RB is selected from C2-C4 alkyl groups substituted with hydroxyl groups and C1-C4 alkyl groups; Cat+ is an ammonium cation of the general formula +NH2RCRD, where residue RC is a C2-C4 alkyl group substituted with hydroxyl groups; and residue RD is selected from C2-C4 alkyl groups substituted with hydroxyl groups and C1-C4 alkyl groups.

Description

Technology Field

[0001] The present invention relates to the technical field of security ink for manufacturing dichroic security features for securing value documents, wherein the dichroic security feature exhibits a first color when viewed under transmitted light and a second color different from the first color when viewed under incident light. Background Technology

[0002] In attempts to protect security documents such as banknotes, documents of value or cards, tax banderols, and product labels—which lack reproducible effects against forgery, alteration, or piracy—due to the continuously improving quality of color copying and printing, it has been common practice to incorporate various security features into these documents.

[0003] Security features, for example in the case of security documents, can generally be classified into "covert" security features and "overt" security features. The protection provided by covert security features relies on the concept that these features are difficult to detect and generally require specialized equipment and knowledge for detection, whereas "overt" security features rely on the concept that they can be easily detected by human senses without assistance; for example, these features may be visible and / or detectable through touch, while still being difficult to manufacture and / or copy. However, the effectiveness of overt security features depends heavily on whether they are easily recognized as security features, because most users, especially those without prior knowledge of the security features of a document or its items, will actually perform a security check based on the security features only when they have actual knowledge of their existence and characteristics.

[0004] A special role in securing valuable documents is played by dichroic security features that display a first color when viewed under transmitted light and a second color distinct from the first when viewed under incident light. To provide a striking effect and attract public attention, the first and second colors must be visually prominent, such as blue, metallic yellow, magenta, and green, as well as exhibit significant color contrast (e.g., blue / metallic yellow, green / metallic yellow, purple / metallic yellow).

[0005] Dichroic security features that appear blue when viewed under transmitted light and metallic yellow when viewed under incident light can be obtained from a silver platelet containing ink.

[0006] International Patent Application Publication No. WO2011064162A2 describes a solvent-based ink containing silver platelets for manufacturing dichroic security, a UV radical curable ink, or a decorative element that exhibits a gold / copper color upon reflection and a blue color upon transmission. The ink contains a high concentration of silver platelets characterized by a weight ratio of 3:1.1 between the silver platelets and the binder. The high concentration of silver platelets or decorative elements in the ink used for security described in WO2011064162A2 is detrimental to the mechanical resistance of the produced security or decorative element and also makes the production process of the element expensive. Furthermore, the mechanical resistance of the security or decorative element described in WO2011064162A2 is compromised by the use of UV radical curable inks or solvent-based inks, which is well known to those skilled in the art and provides a cured coating with limited mechanical resistance. Since mechanical resistance is an essential characteristic of security elements and the manufacturing process described in WO2011064162A2 is time-consuming and somewhat expensive, the ink and manufacturing process described herein are not suitable for the industrial production of value documents with dichroic security features having acceptable mechanical resistance.

[0007] International patent application publication number WO2013186167A2 describes the use of a UV-curable ink containing silver platelets, a radical-curable binder, and a significant amount of organic solvent for coating the surface of a holographic structure. The coated holographic structure exhibits a blue color with high saturation when transmitted to an embossed surface and a yellow color with low saturation when reflected. Although the UV-curable ink described in WO2013186167A2 contains a lower concentration of silver platelets compared to the UV radiation radical-curable ink described in WO2011064162A2, the ink is still not suitable for the industrial production of dichroic features on value documents because, on the one hand, the increased amount of organic solvent is not environmentally friendly and requires an additional air drying step prior to the UV curing step, and on the other hand, the coating obtained with the ink has limited mechanical resistance as well as low saturation when reflected.

[0008] Generally, the industrial printing of value documents requires a high printing speed of 8,000 sheets / hour, and a significant number of value documents are produced from each sheet. For example, in the field of banknote printing, up to 55 value documents, each containing one or more security features, can be manufactured from a single sheet. To be suitable for implementation on a production line, it is essential that the production process of each printable security feature present in the value documents complies with the requirement of the high speed of industrial printing of value documents.

[0009] Therefore, a stable security ink is required to manufacture dichroic security features on value documents at high speeds (i.e., industrial speeds), with improved mechanical resistance, appearing blue under transmitted light and metallic yellow under incident light.

[0010] Summary of the Invention

[0011] Accordingly, the object of the present invention is to provide a UV-Vis radiation cation-curable security ink and a UV-Vis radiation hybrid-curable security ink for producing a dichroic security feature on a value document at a high speed (i.e., industrial speed), having improved mechanical resistance, and exhibiting blue when viewed under transmitted light and metallic yellow when viewed under incident light. This is achieved by the UV-Vis radiation-curable security ink claimed herein, the ink comprising:

[0012] a) As silver nanoplatelets of about 7.5 wt% to about 20 wt%, having an average diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, an average thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and an average aspect ratio greater than 2.0, wherein the average diameter is determined by transmission electron microscopy and the average thickness is determined by transmission electron microscopy,

[0013] The following general formula ( I Silver nanoplatelet comprising a surface stabilizer of );

[0014] ( I )

[0015] In the above formula,

[0016] Remaining R A is a C2-C4 alkyl group substituted with a hydroxyl group;

[0017] Remaining R B is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0018] Cat + is a general formula + NH 2 R C R D It is an ammonium cation of, and residueR C is a C2-C4 alkyl group substituted with a hydroxyl group; residue R D is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0019] b) About 45 weight% to about 80 weight% of a cycloaliphatic epoxide or a mixture of a cycloaliphatic epoxide and one or more UV-Vis radiation-curable compounds;

[0020] c) One or more cationic photoinitiators;

[0021] d) A perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl;

[0022] e) About 3 weight% to about 12 weight% of a polyvinyl chloride copolymer containing at least 60 weight% of vinyl chloride; and optionally,

[0023] f) Up to about 25 weight percent of organic solvent; where weight percent is based on the total weight of the UV-Vis radiation-curable security ink.

[0024] An additional aspect according to the present invention relates to a method for manufacturing a security feature for securing a value document that appears blue when viewed in transmitted light and metallic yellow when viewed in incident light, the method comprising the following steps:

[0025] A) A step of providing an ink layer by printing the UV-Vis radiation-curable security ink claimed and described herein onto a transparent or partially transparent area of ​​a substrate of a value document, preferably by screen printing, rotogravure, or flexography; and

[0026] B)step A) A step of forming security features by UV-Vis curing the ink layer obtained from. Specific details for implementing the invention

[0027] details

[0028] definition

[0029] The following definitions will be discussed in the detailed description and used to interpret the meanings of the terms cited in the claims.

[0030] As used herein, the article "a / an" indicates not only more than one but also one, and does not necessarily limit its reference noun to the singular.

[0031] As used herein, the term “about” means that the amount or value may be a specified specific value or some other value in the vicinity thereof. Generally, the phrase “about” indicating a specific value is intended to indicate a range within ±5% of that value. For example, the phrase “about 100” indicates a range of 100 ± 5, i.e., a range from 95 to 105. Preferably, the range indicated by the term “about” indicates a range of ±3% of the value, more preferably ±1%. Generally, when the term “about” is used, it can be expected that similar results or effects according to the present invention can be obtained within a range of ±5% of the indicated value.

[0032] As used herein, the term “and / or” means that all or only one of the elements of a group may be present. For example, “A and / or B” means “only A, or only B, or both A and B.” In the case of “only A,” it is a term that also encompasses the possibility that B is absent, that is, the possibility that “only A is present and B is absent.”

[0033] The term “comprising” as used herein is intended to be non-exclusive and open. Thus, for example, a solution comprising compound A may comprise other compounds other than A. However, since the term “comprising” also includes the more restrictive meanings of “essentially composed” and “composed” as specific embodiments thereof, for example, a “solution comprising A, B and optionally C” may also be (essentially) composed of A and B, or (essentially) composed of A, B, and C.

[0034] Where this description refers to a "preferred" embodiment / feature, combinations of such "preferred" embodiments / features are also deemed to be disclosed, insofar as the "preferred" embodiment / feature is technically meaningful.

[0035] As used in this specification, the term “one or more” means one, two, three, four, etc.

[0036] The terms "UV-Vis curable" and "UV-Vis curing" refer to radiation curing by photopolymerization under the influence of irradiation having wavelength components in the UV or the UV and visible portions of the electromagnetic spectrum (generally 100 to 800 nm, preferably 150 to 600 nm, more preferably 200 to 400 nm).

[0037] surprisingly,

[0038] a) As silver nanoplatelets of about 7.5 wt% to about 20 wt%, having an average diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, an average thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and an average aspect ratio greater than 2.0, wherein the average diameter is determined by transmission electron microscopy and the average thickness is determined by transmission electron microscopy,

[0039] The following general formula ( I Silver nanoplatelet comprising a surface stabilizer of );

[0040] ( I )

[0041] In the above formula,

[0042] Remaining R A is a C2-C4 alkyl group substituted with a hydroxyl group;

[0043] Remaining R B is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0044] Cat + is a general formula + NH 2 R C R D It is an ammonium cation of, and

[0045] Remaining R C is a C2-C4 alkyl group substituted with a hydroxyl group;

[0046] Remaining R D is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0047] b) About 45 weight% to about 80 weight% of a cycloaliphatic epoxide or a mixture of a cycloaliphatic epoxide and one or more UV-Vis radiation-curable compounds;

[0048] c) One or more cationic photoinitiators;

[0049] d) A perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl;

[0050] e) About 3 weight% to about 12 weight% of a polyvinyl chloride copolymer containing at least 60 weight% of vinyl chloride; and optionally,

[0051] f) Up to approximately 25 weight percent of organic solvent

[0052] It has been found that a UV-Vis radiation-curable security ink, comprising, wherein weight % is based on the total weight of the UV-Vis radiation-curable security ink, enables the rapid and economical manufacture of security features having improved mechanical resistance and exhibiting blue under projected light and metallic yellow under incident light. The general formula described herein ( ICertain silver nanoplatelets comprising a surface stabilizer and certain ink vehicles described herein enable the silver nanoplatelets contained in an ink layer obtained by printing the security ink according to the present invention along the interface between the ink layer and air and the interface between the ink layer and the substrate and along the straight line of the interfaces to form a thin reflective layer, thereby producing metallic yellow upon reflection and blue upon transmission, independent of the thickness of the printed ink layer. The rapid development of metallic yellow upon reflection and blue upon transmission cannot be achieved with inks described in the prior art. The cationic curable binder or hybrid curable binder contained in the UV-Vis radiation-curable security ink claimed herein provides dichroic security features obtained from an ink having high mechanical resistance. The striking visual appearance and the contrast between the blue color in transmitted light and the metallic yellow color in incident light represent security features created by the ink according to the present invention. This helps to focus the attention of general users on the security features, assists in locating and recognizing the security features in value documents, and helps authenticate value documents containing the security features. The UV-Vis radiation-curable ink according to the present invention exhibits excellent shelf stability. Therefore, the UV-Vis radiation-curable security ink according to the present invention is stable, complies with the requirement of high speed for industrial printing of value documents, and provides dichroic security features with striking visual appearance, high value recognition, and excellent mechanical resistance.

[0053] A security feature made of the UV-Vis radiation-curable security ink claimed herein exhibits blue when viewed in transmitted light, i.e., in transmission. For the purposes of the present invention, viewing in transmitted light means that the security feature is illuminated from one side and seen from the opposite side by holding the security feature in front of a light source, for example, with respect to daylight. Blue is observed separately from the side of the security feature that is seen in transmitted light. For the purposes of the present invention, a security feature exhibiting blue refers to a security feature exhibiting blue that is characterized by a chroma value C* (corresponding to a measure of color intensity or color saturation) greater than 20. Intense to very intense blue is characterized by a chroma value C* greater than 30. The chroma value C* is calculated from the a* and b* values ​​according to the CIELAB (1976) color space, and the formula is as follows:

[0054] .

[0055] The a* and b* values ​​in the transmitted light are measured using a Datacolor 650 spectrophotometer (parameters: integrating sphere, diffuse illumination (pulsed xenon D65) and 8˚ viewing, analyzer SP2000 with a dual 256 diode array for a wavelength range of 360 to 700 nm, and a transmission sampling aperture of size 22 nm).

[0056] A security feature made of the UV-Vis radiation-curable security ink claimed herein exhibits a metallic yellow or gold color when viewed in incident light, i.e., reflection. In this patent application, the terms "metallic yellow" and "gold" are used interchangeably. For the purposes of the invention, "viewed in incident light" means that the security feature is illuminated on a surface printed with the security ink claimed herein and is viewed from the same surface. For the purposes of the invention, a security feature exhibiting a metallic yellow or gold color refers to a security feature exhibiting a yellow color characterized by a chroma value C* (corresponding to a measure of color intensity or chroma) calculated from the a* and b* values ​​according to the CIELAB (1976) color space being greater than 20, and the formula is as follows:

[0057] .

[0058] The a* and b* values ​​of the security features were measured at 0° relative to the normal with an illumination angle of 22.5° using a goniometer (Goniometric Spectrophotometer Codec WI-10 5&5 from Phyma GmbH Austria).

[0059] The UV-Vis radiation-curable security ink claimed and described in this specification is preferably selected from screen printing security ink, rotogravure security ink and flexography security ink. Preferably, the UV-Vis radiation-curable security ink claimed herein is characterized by having a viscosity of about 50 mPa·s to about 2000 mPa·s at 25°C, a Brookfield viscometer ("DV-1 Prime Model") equipped with spindle S27 at 100 rpm or a Brookfield viscometer equipped with spindle S21 at 50 rpm is used to measure a viscosity between 500 and 2000 mPa·s, and a Brookfield viscometer equipped with spindle S21 at 100 rpm is used to measure a viscosity of less than 500 mPa·s. The UV-Vis radiation-curable screen printing security ink claimed herein is characterized by having a viscosity of about 50 mPa·s to about 1000 mPa·s at 25°C, preferably about 100 mPa·s to about 1000 mPa·s at 25°C.

[0060] As is known to those skilled in the art, the term rotogravier is, for example, Handbook of Print MediaIt refers to the printing process described in Helmut Kipphan, Springer Edition, page 48. Rotogravure is a printing process that engraves image elements onto the surface of a cylinder. The non-image area is at a certain original level. Before printing, the entire printing plate (non-image and printing elements) is coated with ink and filled with ink. Before printing, ink is removed from the non-image using a wiper or blade so that the ink remains only in the cells. The image is transferred from the cells to the substrate by pressure generally within the range of 2 to 4 bar and the adhesion between the substrate and the ink. The term rotogravure does not include, for example, intaglio printing processes that rely on other types of ink (also referred to in the art as engraved steel die or copper plate printing processes).

[0061] The flexographic printing process preferably uses a device equipped with a chambered doctor blade, anilox roller, and a plate cylinder. It is advantageous for the anilox roller to have small cells, the volume and / or density of which determine the ink or varnish application rate. The chambered doctor blade is placed against the anilox roller to fill the cells while simultaneously scraping off excess ink or varnish. The anilox roller transfers the ink to the plate cylinder, which ultimately transfers the ink to the substrate. The plate cylinder can be made of polymer or elastomeric material. Polymers are primarily used as photopolymers in plates and sometimes as seamless coatings for sleeves. Photopolymer plates are made of photosensitive polymers that cure under ultraviolet (UV) light. The photopolymer plate is cut to the required size and placed in a UV light exposure device. One side of the plate is fully exposed to UV light to harden or cure the base of the plate. Then, the plate is flipped over, the negative of the work is mounted on the uncured side, and the plate is further exposed to UV light. This process cures the plate in the image area. Then, the plate is processed to remove uncured photopolymer from the non-image area, lowering the plate surface in these non-image areas. After processing, the plate is dried, and a quantitative irradiation is performed after exposure to UV light to cure the entire plate. The preparation of the plate cylinder for flexography is Printing Technology , JM Adams and P. A. Dolin, Delmar Thomson Learning, 5th Edition, It is explained on pages 359-360.

[0062] As is well known to those skilled in the art, screen printing (also known as silkscreen printing in the art) is a printing technique that uses a screen made of woven mesh to support an ink-blocking stencil. The attached stencil forms an open area of ​​the mesh that transfers the ink onto the substrate as a sharp-edged image. A squeegee moves across the screen with the ink-blocking stencil, allowing the ink to pass through the threads of the woven mesh in the open area. An important feature of screen printing is that ink can be applied to the substrate in a thicker thickness than in other printing techniques. Therefore, screen printing is desirable even when ink deposits with a thickness of about 10 to 50 μm or greater, which cannot be (easily) achieved with other printing techniques, are required. Generally, the screen is made of a piece of porous, finely woven fabric called a mesh, stretched over a frame, for example, of aluminum or wood. Currently, most meshes are made of synthetic materials, such as synthetic or steel threads. The preferred synthetic material is nylon or polyester thread.

[0063] In addition to screens made based on woven meshes based on synthetic or metal threads, screens are developed from solid metal steel having a grid of holes. Such screens are manufactured by a method comprising the steps of forming a screen frame on a matrix provided with a separator in a first electrolytic cell, peeling the formed screen frame from the matrix, and electrolyzing the screen frame in a second electrolytic cell to deposit metal on the frame to electrolyze the metal screen.

[0064] There are three types of screen printing presses: flat-bed, cylinder, and rotary. Flat-bed and cylinder screen printing presses are similar in that they both perform printing operations using a flat screen and a three-stage reciprocating process. The screen first moves to a position on the substrate, then a squeegee is pressed against the mesh and pulled over the image area, and then the screen is lifted from the substrate to complete the process. For flat-bed presses, the substrate to be printed is typically placed on a horizontal printing bed parallel to the screen. For cylinder presses, the substrate is mounted on a cylinder. Flat-bed and cylinder screen printing processes are discontinuous, and therefore speeds are generally limited to a maximum of 45 m / min in web processes or 3,000 sheets / hour in sheet-fed processes.

[0065] Conversely, rotary screen presses are designed for continuous high-speed printing. The screen used in a rotary screen press is a thin metal cylinder, typically obtained using the aforementioned electroforming method or made of woven steel threads. The open-ended cylinder is capped at both ends and fitted into a block on the side of the press. During printing, ink is pumped into one end of the cylinder to ensure a constant supply of new ink. A squeegee is fixed inside the rotating screen, and the squeegee pressure is maintained and adjusted for good and consistent print quality. An advantage of the rotary screen press is that it can easily reach speeds of 150 m / min in the web or 10,000 sheets / hour in the sheet-feed process.

[0066] Screen printing is, for example, The Printing Ink Manual , RH Leach and RJ Pierce, Springer Edition, 5th Edition, pp. 58-62; Printing Technology, JM Adams and PA Dolin, Delmar Thomson Learning, 5th Edition, pp. 293–328 and Handbook of Print Media , H. Kipphan, Springer, pp. 409-422 and 498-499, as further explained.

[0067] More preferably, the UV-Vis radiation-curable security ink claimed and described herein is a screen-printed security ink. Because this UV-Vis radiation-curable screen-printed security ink enables ultra-high-speed printing of dichroic security features having a thickness of at least about 4 μm, it is particularly useful for the industrial production of dichroic security features on value documents.

[0068] The UV-Vis radiation-curable ink claimed and described in this specification a) The following general formula ( I It contains about 7.5 wt% to about 20 wt%, preferably about 7.5 wt% to about 15 wt%, more preferably about 10 wt% to about 13 wt% of silver nanoplatelets comprising a surface stabilizer of ):

[0069] ( I )

[0070] In the above formula,

[0071] Remaining R A is a C2-C4 alkyl group substituted with a hydroxyl group;

[0072] Remaining R B is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0073] Cat + is a general formula + NH 2 R C R D It is an ammonium cation of, and

[0074] Remaining R C is a C2-C4 alkyl group substituted with a hydroxyl group;

[0075] Remaining R D is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups.

[0076] General formula ( IThe silver nanoplatelets described herein, comprising a surface stabilizer, can be easily dispersed within the vehicle of the UV-Vis radiation-curable security ink claimed herein. Upon printing, the silver nanoplatelets described herein migrate from the ink layer mass obtained with the UV-Vis radiation-curable security ink claimed herein at the interface between the ink layer and air and at the interface between the ink layer and the substrate, and align to form a thin layer of silver nanoplatelets at the interface, thereby inducing a rapid development of metallic yellow coloration observed in incident light. This characteristic of the UV-Vis radiation-curable security ink claimed herein is particularly advantageous because, on the one hand, the time required for the development of metallic yellow coloration is compatible with the requirement of high speed in industrial printing of value documents, and on the other hand, it enables the production of dichroic security features with an ink containing as little as 7.5 wt% of silver nanoplatelets, thereby significantly reducing the production cost of dichroic security features, particularly those having a large thickness of at least about 4 μm. Depending on the thickness of the dichroic security feature to be produced and the composition of the ink vehicle, the amount of silver nanoplatelets in the UV-Vis radiation-curable security ink can be adjusted so that the metallic yellow in reflected light develops quickly without affecting the hue and saturation of the blue in transmitted light.

[0077] The silver nanoplatelets contained in UV-Vis may be in the form of a disk, a regular hexagon, a triangle, particularly an equilateral triangle, and a truncated triangle, particularly a truncated equilateral triangle, or a mixture thereof. They are preferably in the form of a disk, a truncated triangle, a hexagon, or a mixture thereof.

[0078] The average diameter of the silver nanoplatelets is within the range of 50 to 150 nm, preferably 60 to 140 nm, more preferably 70 to 120 nm, with a standard deviation of less than 60%, preferably less than 50%. The diameter of the silver nanoplatelets is the longest dimension of the silver nanoplatelets and corresponds to the maximum dimension of the silver nanoplatelets when oriented parallel to the plane of the transmission electron microscope (TEM) image. As used herein, the term “average diameter of silver nanoplatelets” refers to the average diameter measured by transmission electron microscope (TEM) using Fiji image analysis software based on measurements of at least 300 randomly selected silver nanoplatelets oriented parallel to the plane of the transmission electron microscope (TEM), and the diameter of the silver nanoplatelets is the maximum dimension of the silver nanoplatelets oriented parallel to the plane of the transmission electron microscope (TEM) image. TEM analysis was performed using a ZEISS EM 910 instrument in bright field mode at an e-beam acceleration voltage of 100 kV. A dispersion of silver nanoplatelets in isopropanol at a suitable concentration, preferably less than 24.1 wt%, was used to perform TEM analysis.

[0079] The average thickness of the silver nanoplatelets is within the range of 5 to 30 nm, preferably 7 to 25 nm, more preferably 8 to 25 nm, with a standard deviation of less than 50%, preferably less than 30%. The thickness of the silver nanoplatelets is the shortest dimension of the nanoplatelets and corresponds to the maximum thickness of the silver nanoplatelets. As used herein, the term “average thickness of silver nanoplatelets” refers to the average thickness determined by transmission electron microscopy (TEM) based on manual measurements of at least 50 randomly selected silver nanoplatelets oriented perpendicular to the plane of the TEM image, and the thickness of the silver nanoplatelets is the maximum thickness of the silver nanoplatelets. TEM analysis was performed using a ZEISS EM 910 instrument in bright-field mode at an e-beam acceleration voltage of 100 kV. A dispersion of silver nanoplatelets in isopropanol at a suitable concentration, preferably less than 24.1 wt%, was used to perform TEM analysis.

[0080] The average aspect ratio of the silver nanoplatelets (defined as the ratio between the average diameter and the average thickness) is greater than 2.0, preferably greater than 2.2, and more preferably greater than 2.5.

[0081] Preferably, the average diameter of the silver nanoplatelets is in the range of 70 to 120 nm with a standard deviation of less than 50%, the average thickness of the silver nanoplatelets is in the range of 8 to 25 nm with a standard deviation of less than 30%, and the average aspect ratio of the silver nanoplatelets is greater than 2.5.

[0082] The silver nanoplatelets used in the UV-Vis radiation-curable ink described herein are characterized by having a maximum value of the maximum absorption wavelength between 560 and 800 nm, preferably between 580 and 800 nm, and more preferably between 600 and 800 nm. The maximum value of the maximum absorption wavelength is approximately 5 x 10⁻¹⁰ using a Varian Cary 50 UV-Vis spectrophotometer. -5Measurements were taken in water at a silver concentration of M (mol / L). The absorbance peak has a full width at half maximum (FWHM) value within the range of 50 to 500 nm, preferably 70 to 450 nm, and more preferably 80 to 450 nm. The molar extinction coefficient of the silver nanoplatelet measured at the maximum absorption wavelength is 4000 L / (cm*mol Ag Exceeding ) 5000 L / (cm*mol) Ag Exceeding ) very, especially 6000 L / (cm*mol Ag It exceeds )

[0083] The silver nanoplatelets contained in the UV-Vis radiation-curable ink claimed in this specification are of the following general formula ( I Includes a stabilizer of ):

[0084] ( I )

[0085] In the above formula, the residue R A is a C2-C4 alkyl group substituted with a hydroxyl group; residue R B is selected from C2-C4 alkyl groups substituted with hydroxyl groups and C1-C4 alkyl groups; Cat + is a general formula + NH 2 R C R D It is an ammonium cation of, and residue R C is a C2-C4 alkyl group substituted with a hydroxyl group; residue R D is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups. Without being bound by theory, the general formula ( IIn addition to preventing the aggregation and sedimentation of silver nanoplatelets in the security ink claimed herein, the surface stabilizer is believed to help facilitate the migration of silver nanoplatelets from the mass of the ink layer obtained with the security ink claimed herein at the interface between the ink layer and air and at the interface between the ink layer and the substrate.

[0086] General formula ( I The surface stabilizer of the silver nanoplatelet may be present in an amount of about 0.5% to about 5%, preferably about 0.5% to about 4%, and more preferably 3% with respect to the weight% of the silver nanoplatelet.

[0087] As used herein, the term “C1-C4 alkyl group” refers to a saturated straight-chain or branched-chain monovalent hydrocarbon radical having 1 to 4 carbon atoms (C1-C4). Examples of C1-C4 alkyl groups are methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl ( n -Pr, n -Profile, -CH2CH2CH3), 2-Profile( i -Pr, iso -propyl, -CH(CH3)2), 1-butyl( n -Bu, n -butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl( i -Bu, i -butyl, -CH2CH(CH3)2), 2-butyl( s -Bu, s -butyl, -CH(CH3)CH2CH3) and 2-methyl-2-propyl( t -Bu, t It includes -butyl, -C(CH3)3).

[0088] The term “hydroxyl group substituted C2-C4 alkyl group” refers to a straight-chain or branched-chain alkyl group having 2 to 4 carbon atoms substituted with a hydroxyl group (-OH). The C2-C4 alkyl group may be substituted with one or two hydroxyl groups.

[0089] General formula (I In ), residue R A can be a C2-C4 alkyl group substituted with two hydroxyl groups and a residue R B It can be a C1-C4 alkyl group.

[0090] In a preferred embodiment according to the present invention, residue R A and R B is a C2-C4 alkyl group independently substituted with a hydroxyl group, preferably one hydroxyl group. Accordingly, in an embodiment according to the present invention, the residue R A and R B The residues are independently selected from the group consisting of -CH2CH2OH, -CH2CH(OH)CH3, -CH2CH2CH2OH, -CH(CH3)(CH2OH), -CH2CH(OH)CH2CH3, -CH2CH2CH(OH)CH3-CH2CH2CH2CH2OH, -CH(CH3)CH(OH)CH3, -CH(CH2OH)CH2CH3, -CH(CH3)CH2CH2OH, -CH2CH(CH2OH)CH3, -CH2C(CH3)(OH)CH3, -CH2CH(CH3)CH2(OH), -CH2C(OH)(CH3)2 and -CH2C(CH3)(CH2OH), and more preferably selected from the group consisting of -CH2CH2OH, -CH2CH(OH)CH3 and -CH2CH2CH2OH. R A and R B It may be the same or different.

[0091] General formula ( I In ), residue R C can be a C2-C4 alkyl group substituted with two hydroxyl groups and a residue R D It can be a C1-C4 alkyl group.

[0092] In a preferred embodiment according to the present invention, residue R C and R D is a C2-C4 alkyl group independently substituted with a hydroxyl group, preferably one hydroxyl group. Accordingly, in an embodiment according to the present invention, the residue R C and R D The residues are independently selected from the group consisting of -CH2CH2OH, -CH2CH(OH)CH3, -CH2CH2CH2OH, -CH(CH3)(CH2OH), -CH2CH(OH)CH2CH3, -CH2CH2CH(OH)CH3-CH2CH2CH2CH2OH, -CH(CH3)CH(OH)CH3, -CH(CH2OH)CH2CH3, -CH(CH3)CH2CH2OH, -CH2CH(CH2OH)CH3, -CH2C(CH3)(OH)CH3, -CH2CH(CH3)CH2(OH), -CH2C(OH)(CH3)2 and -CH2C(CH3)(CH2OH), and more preferably selected from the group consisting of -CH2CH2OH, -CH2CH(OH)CH3 and -CH2CH2CH2OH. R C and R D It may be the same or different.

[0093] Preferably, general formula ( I Residuals in ) R A , R B , R C and R D is a C2-C4 alkyl group independently substituted with a single hydroxyl group. More preferably, the general formula ( I Residuals in ) R A , R B , R C and R D is independently selected from the group consisting of -CH2CH2OH, -CH2CH(OH)CH3, and -CH2CH2CH2OH. More preferably, the general formula ( I Residuals in ) R A , R B , R C and R D represents -CH2CH2OH.

[0094] To prevent aggregation and sedimentation of silver nanoplatelets during storage, the silver nanoplatelets may include an additional surface stabilizer on their surface.

[0095] In a preferred embodiment, silver nanoplatelets have the following general formula ( II Includes an additional surface stabilizer of ):

[0096] ( II )

[0097] In the above formula,

[0098] R 1 H, C1-C 18 It is alkyl, phenyl, C1-C8alkylphenyl, or CH2COOH;

[0099] R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are independently H, C1-C8 alkyl or phenyl;

[0100] Y is O or NR 8 And;

[0101] R 8 is H or C1-C8 alkyl;

[0102] k1 is an integer within the range of 1 to 500;

[0103] k2 and k3 are independently 0 or integers within the range of 1 to 250;

[0104] k4 is 0 or 1 and;

[0105] k5 is an integer within the range of 1 to 5. Preferably, the general formula ( II )at Y represents O. Also preferably, the general formula ( II )at k4 is 0.

[0106] General formula ( II Average molecular weight (M) of the surface stabilizer n ) is preferably 1,000 to 20,000 [g / mol], more preferably 1,000 to 10,000 [g / mol], and most preferably 1,000 to 6,000 [g / mol].

[0107] For example, general formula ( I When the surface stabilizer of ) includes ethylene oxide units (EO) and propylene oxide units (PO), the order of (EO) and (PO) may be fixed (block copolymer) or not fixed (random copolymer).

[0108] Preferably, general formula ( II )at, R 1 H or C1-C 18 It is alkyl, and R 2 , R 3 , R 4 , R 5 , R 6 and R 7 They are independently H, CH3, or C2H5, and k1is an integer within the range of 22 to 450, and k2 and k3 are independently 0 or integers in the range of 1 to 250, and k4 is 0 or 1, and k5 is an integer within the range of 1 to 5. More preferably, the general formula ( II )at R 1 It is H or C1-C4 alkyl, and R 2 , R 3 , R 4 , R 5 , R 6 and R 7 They are independently H or CH3, and k1 is an integer within the range of 22 to 450, and k2 and k3 are independently 0 or integers in the range of 1 to 100, and k4 is 0, and k5 is an integer within the range of 1 to 4.

[0109] The most desirable general formula ( II The surface stabilizer of ) is the following general formula ( II-a has:

[0110] ( II-a )

[0111] In the above formula,

[0112] R 1 is H or a C1-C8 alkyl group, particularly H or CH3, and

[0113] k1 It is an integer within the range of 22 to 450, particularly 22 to 150.

[0114] General formula ( IIA desirable surface stabilizer of ) is, for example, an average molecular weight (M) of 2,000 to 6,000, such as MPEG 2000 thiol, MPEG 3000 thiol, MPEG 4000 thiol, MPEG 5000 thiol, and MPEG 6000 thiol. n MPEG thiols (poly(ethylene glycol)methyl ether thiols) having ), for example, PEG 2000 thiol, PEG 3000 thiol, PEG 4000 thiol, PEG 5000 thiol, PEG 6000 thiol, with an average M of 2000 to 6000. n It is derived from PEG thiol (O-(2-mercaptoethyl)-poly(ethylene glycol)) having.

[0115] The silver nanoplatelets contained in the security ink may further comprise a surface stabilizer which is a polymer or copolymer described in WO200674969A1, and this can be obtained by a method comprising the following steps:

[0116] i-1) Structural elements A step of polymerizing one or more ethylene-based unsaturated monomers in the first step in the presence of at least one nitroxyl ether having,

[0117] X represents a group having at least one carbon atom X A step in which a free radical X· derived from can initiate polymerization; or

[0118] i-2) At least one stable free nitroxyl radical and a step of polymerizing one or more ethylene-based unsaturated monomers in the first step in the presence of a free radical initiator;

[0119] Step here i-1) or i-2) At least one monomer used in is a C1-C6 alkyl or hydroxy C1-C6 alkyl ester of acrylic acid or methacrylic acid; optionally

[0120] ii) i-1) or i-2) A second step comprising modifying the polymer or copolymer prepared according to by an ester exchange reaction, amidation, hydrolysis, or anhydride modification, or a combination thereof.

[0121] step i-1) or i-2) The monomer in is preferably 4-vinyl-pyridine or pyridinium-ion, 2-vinyl-pyridine or pyridinium-ion, 1-vinyl-imidazole or imidazolinium-ion, or formula CH 2 =C(R a )-(C=Z)-R b It can be selected from the compounds of,

[0122] R a is hydrogen or methyl;

[0123] R b is NH2, O - (Me + ), unsubstituted C1-C 18 Alkoxy, C2-C hindered by at least one N and / or O atom 100 Alkoxy or hydroxy-substituted C1-C 18 Alkoxy, unsubstituted C1-C 18 Alkylamino, unsubstituted di(C1-C 18 Alkyl)amino, hydroxy-substituted C1-C 18 alkylamino or hydroxy-substituted di(C1-C 18 Alkyl)amino, -O(CH2) y NR 15 R 16 or -O(CH2) y N + HR 15 R 16 An - , -N(CH2) y NR 15 R 16 or -N(CH2) y N + HR15 R 16 An - And,

[0124] An - is an anion of a monovalent organic or inorganic acid;

[0125] y is an integer from 2 to 10;

[0126] R 15 It is a saturated or unsaturated, straight-chain or branched-chain alkyl with 1 to 22 carbon atoms;

[0127] R 16 It is a saturated or unsaturated, straight-chain or branched-chain alkyl with 1 to 22 carbon atoms;

[0128] Me + is a monovalent metal atom or an ammonium ion;

[0129] Z is oxygen or sulfur.

[0130] Phase 2 ii) is preferably an ester exchange reaction. Step ii) In this case, alcohol is preferably a food R c -[O-CH 2 -CH 2 -] c -OH It is an ethoxylate of, R c is a saturated or unsaturated, straight-chain or branched-chain alkyl with 1 to 22 carbon atoms, or an alkylaryl or dialkylaryl with up to 24 carbon atoms, and c It is 1 to 150.

[0131] Preferably, step i-1) or i-2)The process is performed twice and a block copolymer is obtained, wherein in the first or second radical polymerization step, the monomer or monomer mixture contains 50 to 100 weight percent of a C1-C6 alkyl ester of acrylic acid or methacrylic acid based on the total monomer, and in each of the second or first radical polymerization step, the ethylene-based unsaturated monomer or monomer mixture contains at least one monomer without primary or secondary ester bonds.

[0132] In the first polymerization step, the monomer or monomer mixture contains 50 to 100 weight% of a C1-C6 alkyl ester of acrylic acid or methacrylic acid based on the total monomer (first monomer), and in the second polymerization step, the ethylene-based unsaturated monomer or monomer mixture comprises 4-vinyl-pyridine or pyridinium-ion, 2-vinyl-pyridine or pyridinium-ion, vinyl-imidazole or imidazolinium-ion, 3-dimethylaminoethylacrylamide, 3-dimethylaminoethylmethacrylamide or the corresponding ammonium ion, 3-dimethylaminopropylacrylamide or the corresponding ammonium ion, or 3-dimethylaminopropylmethacrylamide or the corresponding ammonium ion (second monomer).

[0133] Preferably, the nitroxyl ether has a structure has

[0134] The surface stabilizer is preferably a copolymer that can be obtained by a method comprising the following steps:

[0135] i-2) Structural elements A step of polymerizing, in the presence of at least one nitroxyl ether having, a first monomer which is a hydroxy C1-C6 alkyl ester of C1-C6 alkyl, acrylic acid, or methacrylic acid, and a second monomer selected from 4-vinyl-pyridine or pyridinium-ion, 2-vinyl-pyridine or pyridinium-ion, 1-vinyl-imidazole or imidazolinium-ion, 3-dimethylaminoethylacrylamide, 3-dimethylaminoethylmethacrylamide, 3-dimethylaminopropylacrylamide, and 3-dimethylaminopropylmethacrylamide in the first step; and

[0136] ii) i-1) The step of modifying a polymer or copolymer prepared according to [the method] by an ester exchange reaction, wherein the step ii) Alcohol in [location] is [food] R c -[O-CH 2 -CH 2 -] c -OH It is an ethoxylate of, R c is a saturated or unsaturated, straight-chain or branched-chain alkyl with 1 to 22 carbon atoms, or an alkylaryl or dialkylaryl with up to 24 carbon atoms, and c 1 to 150 people, Stage 2.

[0137] Preferably, the surface stabilizer obtained through the method described herein is of the following formula ( III It is a copolymer of:

[0138] ( III )

[0139] In the above formula,

[0140] R 17a , R 17b and R 17c are independently H or methyl;

[0141] R 18a and R 18b is H or methyl;

[0142] R 19a is a saturated or unsaturated, straight-chain or branched-chain alkyl having 1 to 22 carbon atoms;

[0143] R 19b is R c -[O-CH2-CH2-] c -O- and;

[0144] R 19c Is

[0145] , , , , , , -C(=O)-NH-(CH2) y NR 15 R 16 or -C(=O)-NH-(CH2) y N + HR 15 R 16 An - And;

[0146] An - is an anion of a monovalent organic or inorganic acid;

[0147] y is an integer from 2 to 10;

[0148] R 15 It is a saturated or unsaturated, straight-chain or branched-chain alkyl with 1 to 22 carbon atoms;

[0149] R 16 It is a saturated or unsaturated, straight-chain or branched-chain alkyl with 1 to 22 carbon atoms;

[0150] R c is a saturated or unsaturated, straight-chain or branched-chain alkyl having 1 to 22 carbon atoms, or an alkylaryl or dialkylaryl having up to 24 carbon atoms, and c is 1 to 150;

[0151] y1 , y2 and y3 are independent integers from 1 to 200. General formula( III The exponent in ) y1 and y2 Regarding this, the order of monomers may be fixed (block copolymer) or not fixed (random copolymer).

[0152] General formula ( III A surface stabilizer of ) is described in International Patent Application Publication No. WO200674969A1.

[0153] Desirable general formula ( III The surface stabilizer of ) is the following general formula ( III-a It is a compound of:

[0154] ( III-a )

[0155] In the above formula,

[0156] R 18a and R 18b is H or methyl;

[0157] y1 , y2 and y3 are independent integers from 1 to 200;

[0158] c is an integer from 1 to 150. The exponent y1 and y2 Regarding this, the order of monomers may be fixed (block copolymer) or not fixed (random copolymer).

[0159] An example of a preferred copolymer used as a surface stabilizer is WO200674969A1. Example A3 and Example A6 It is a copolymer described in

[0160] To improve the stability of the optical properties of silver nanoplatelets upon storage or thermal exposure, silver nanoplatelets are provided with the following general formula ( IV It may include an additional surface stabilizer of ):

[0161] ( IV )

[0162] In the above formula,

[0163] R 9 is a hydrogen atom or formula -CHR 11 -N(R 12 )(R 13 It is the basis of );

[0164] R 10 is a hydrogen atom, a halogen atom, a C1-C8 alkoxy group, or a C1-C8 alkyl group;

[0165] R 11 is H or C1-C8 alkyl;

[0166] R 12 and R 13 They are independently C1-C8 alkyl, hydroxyC1-C8 alkyl groups, or the formula -[(CH2CH2)-O] n1 It is a -CH2CH2-OH group, and n1 It is 1 to 5.

[0167] ceremony( IV Examples of compounds of ) include, but are not limited to, the following:

[0168] , , , , , and .

[0169] A dispersion of silver nanoplatelets used for the manufacture of the UV-Vis radiation-curable security ink claimed herein can be obtained using a method comprising the following steps:

[0170] 1) The following formula ( II A step of preparing a solution containing a silver precursor, which is a compound of );

[0171] ( II )

[0172] In the above formula,

[0173] R 1 H, C1-C 18 It is alkyl, phenyl, C1-C8alkylphenyl, or CH2COOH;

[0174] R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are independently H, C1-C8 alkyl or phenyl;

[0175] Y is O or NR 8 And;

[0176] R 8 is H or C1-C8 alkyl;

[0177] k1 is an integer within the range of 1 to 500;

[0178] k2 and k3 are independently 0 or integers within the range of 1 to 250;

[0179] k4 is 0 or 1 and;

[0180] k5 is an integer within the range of 1 to 5;

[0181] A polymer or copolymer obtainable by a method comprising the following steps:

[0182] i-1) Structural elements A step of polymerizing one or more ethylene-based unsaturated monomers in the first step in the presence of at least one nitroxyl ether having,

[0183] X A step in which represents a group having at least one carbon atom and a free radical X· derived from X can initiate polymerization; or

[0184] i-2) At least one stable free nitroxyl radical and a step of polymerizing one or more ethylene-based unsaturated monomers in the first step in the presence of a free radical initiator, wherein the step i-1) or i-2) A step in which at least one monomer used is a C1-C6 alkyl or hydroxy C1-C6 alkyl ester of acrylic acid or methacrylic acid; and optionally

[0185] ii) i-1) or i-2) A second step comprising modifying the polymer or copolymer prepared according to by an ester exchange reaction, amidation, hydrolysis, or anhydride modification, or a combination thereof.

[0186] Water and optionally a defoamer;

[0187] 2) A step of preparing a solution comprising a reducing agent containing at least one boron atom within a molecule and water;

[0188] 3) step 1) The solution obtained from step 2) A step of adding to a solution obtained from and adding one or more complexing agents;

[0189] 4) Step of adding a hydrogen peroxide solution to water; and

[0190] 5) step 4)A step of adding one or more surface stabilizers to the mixture obtained from.

[0191] The silver precursor is selected from the group consisting of: AgNO3; AgClO4; Ag2SO4; AgCl; AgF; AgOH; Ag2O; AgBF4; AgIO3; AgPF6; R 200 is unsubstituted or substituted C1-C 18 Alkyl, unsubstituted or substituted C 5- -C8-cycloalkyl, unsubstituted or substituted C7-C 18 Aralkyl, unsubstituted or substituted C6-C 18 Aryl or unsubstituted or substituted C2-C 18 Heteroaryl R 200 CO2Ag, R 200 SO3Ag; a silver(I) compound selected from the group consisting of dicarboxylic acids, tricarboxylic acids, polycarboxylic acids, polysulfonic acids, Ag salts of P-containing acids and mixtures thereof, preferably: silver nitrate, silver acetate, silver perchlorate, silver methanesulfonate, silver benzenesulfonate, silver toluenesulfonate, silver trifluoromethanesulfonate, silver sulfate, silver fluoride and mixtures thereof, more preferably silver nitrate.

[0192] The reducing agent is selected from the group consisting of alkali or alkaline earth metal borohydrides such as sodium borohydride, alkali or alkaline earth metal acyloxyborohydrides such as sodium triacetoxyborohydride, alkali or alkaline earth metal alkoxy- or aryloxyborohydrides such as sodium trimethoxyborohydride, aryloxyboranes such as catecholborane, and amine-borane complexes such as diethylaniline borane, tert-butylamine borane, morpholine borane, dimethylamine borane, triethylamine borane, pyridine borane, ammonia borane, and mixtures thereof. Sodium borohydride is most preferred.

[0193] One or more complexing agents are selected from the group of chlor-containing compounds capable of releasing chloride ions under reaction conditions, such as metal chlorides, alkyl or arylammonium chlorides, and phosphonium chlorides; primary or secondary amines such as methylamine or dimethylamine and corresponding ammonium salts; ammonia and corresponding ammonium salts; and aminocarboxylic acids such as ethylenediaminetetraacetic acid and salts thereof.

[0194] Non-limiting examples of complexing agents are ammonia, methylamine, dimethylamine, ethylamine, ethylenediamine, diethylenetriamine, ethylene-diamine-tetraacetic acid (EDTA); ethylenediamine N,N'-disuccinic acid (EDDS); methyl glycine diacetic acid (MGDA); diethylenetriamine pentaacetic acid (DTPA); propylene diamine tetraacetic acid (PDTA); glutamic acid N,N-diaacetic acid (N,N-dicarboxymethyl glutamic acid tetrasodium salt (GLDA)); nitrilotriacetic acid (NTA) and any salts thereof; For example, it includes N-hydroxyethylethylenediaminetri-acetic acid (HEDTA), triethylenetetraaminehexaacetic acid (TTHA), N-hydroxyethyliminodiacetic acid (HEIDA), dihydroxyethylglycine (DHEG), ethylenediaminetetrapropionic acid (EDTP) and derivatives thereof, such as trisodium salt of methylglycine diacetic acid (Na3MGDA) and tetrasodium salt of EDTA.

[0195] Antifoaming agents are compounds or compositions capable of inhibiting foam formation in reaction mixtures, such as commercially available TEGO® Foamex 1488, 1495, 3062, 7447, 800, 8030, 805, 8050, 810, 815N, 822, 825, 830, 835, 840, 842, 843, 845, 855, 860, 883, K3, K7, K8, N, Sigma’s Antifoam SE-15, Struktol SB-2080, etc. The amount of defoaming agent is within the range of 0.00001% to 5% by weight, preferably 0.0001% to 3% by weight, and more preferably 0.001% to 2% by weight, based on the total weight of the reaction mixture before the addition of hydrogen peroxide.

[0196] The antifoaming agent is a step 1) Solution and / or step prepared in 2) It can be added to a solution manufactured in.

[0197] The silver nanoplatelet formation reaction is carried out by gradually adding a silver precursor solution to a reducing agent solution, while the temperature of both solutions is between -3°C and 40°C and the gradual addition is completed within 15 minutes to 24 hours.

[0198] step 4) and / or 5) The silver nanoplatelets obtained from may be subjected to further purification and / or separation methods such as decantation, (ultra)filtration, (ultra)centrifugation, reversible or irreversible aggregation, phase transfer by an organic solvent, and combinations thereof. The dispersion of silver nanoplatelets may contain up to 99 weight%, preferably 5 weight% to 99 weight%, more preferably 5 weight% to 90 weight% of silver nanoplatelets based on the total weight of the dispersion.

[0199] Starting from silver nanoplatelets obtained by purification and / or separation, general formula ( I Silver nanoplatelets containing a stabilizer of ) can be manufactured by the following:

[0200] i) In the presence of nanoplatelets, CS2 is expressed in equation R A R B React with an amine of NH and then R C R D Step to process as NH or

[0201] ii) CS2 is the formula R A R B React with an amine of NH and then R C R D general formula by processing with NH ( I Step of reacting the dithiocarbamate of ) with silver nanoplatelets.

[0202] General formula ( I Silver nanoplatelets containing ) dithiocarbamate can be obtained starting from silver nanoplatelets subjected to the following purification and / or separation methods:

[0203] iii) In the presence of nanoplatelets, CS2 is expressed in equation R A R B A step of reacting with an amine of NH; or

[0204] iv) CS2 is the formula R A R B By reacting with an amine of NH, the general formula ( I ) dithiocarbamate ( I Step of reacting with silver nanoplatelets after obtaining ).

[0205] The silver nanoplatelets described in this specification are disclosed by European patent application no. 20206698.1, titled “Composition comprising silver nanoplatelets,” filed by BASF SE on November 10, 2020.

[0206] The UV-Vis radiation-curable security ink claimed in this specification b) It contains about 45 weight% to about 80 weight% of a cycloaliphatic epoxide or a mixture of a cycloaliphatic epoxide and one or more UV-Vis radiation-curable compounds. One or more UV-Vis radiation-curable compounds may comprise one or more cationic curable monomers and / or one or more radical curable monomers and / or oligomers. Where one or more UV-Vis radiation-curable compounds comprise one or more radical curable monomers and / or oligomers, the UV-Vis radiation-curable security ink claimed herein g) It further comprises one or more free radical photoinitiators. Accordingly, the present invention relates to a UV-Vis radiation-curable security ink for producing a security feature that exhibits blue when viewed under transmitted light and metallic yellow when viewed under incident light, said ink comprising the following:

[0207] a) As silver nanoplatelets of about 7.5 wt% to about 20 wt%, having an average diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, an average thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and an average aspect ratio greater than 2.0, wherein the average diameter is determined by transmission electron microscopy and the average thickness is determined by transmission electron microscopy,

[0208] The following general formula ( I Silver nanoplatelet comprising a surface stabilizer of );

[0209] ( I )

[0210] In the above formula,

[0211] Remaining R A is a C2-C4 alkyl group substituted with a hydroxyl group;

[0212] Remaining R B is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0213] Cat + is a general formula + NH 2 R C R D It is an ammonium cation of, and

[0214] Remaining R C is a C2-C4 alkyl group substituted with a hydroxyl group;

[0215] Remaining R D is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0216] b) b-1) About 45 weight% to about 80 weight% of cycloaliphatic epoxide;

[0217] b-2) A mixture of about 45% by weight to about 80% by weight of a cycloaliphatic epoxide and one or more cationic curable monomers;

[0218] b-3) A mixture of about 45 weight% to about 80 weight% of a cycloaliphatic epoxide and one or more radical-curable monomers and / or oligomers; or

[0219] b-4) A mixture of a cycloaliphatic epoxide, one or more cationic curable monomers, and one or more radical curable monomers and / or oligomers, in an amount of about 45% to about 80% by weight, preferably about 45% to about 65% by weight;

[0220] c) One or more cationic photoinitiators;

[0221] d)A perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl;

[0222] e) About 3 weight% to about 12 weight% of a polyvinyl chloride copolymer containing at least 60 weight% of vinyl chloride; and optionally,

[0223] f) Up to approximately 25 weight percent of organic solvent; provided that the security ink b-3) or b-4) If it includes, security ink is g) It further comprises one or more free radical photoinitiators; weight % is based on the total weight of the UV-Vis radiation-curable security ink.

[0224] A preferred embodiment according to the present invention relates to a UV-Vis radiation cation-curable security ink for producing a security feature that exhibits blue when viewed under transmitted light and metallic yellow when viewed under incident light (i.e., an ink containing only a cation-curable monomer and not a radical-curable monomer / oligomer), wherein the ink comprises the following:

[0225] a) As silver nanoplatelets of about 7.5 wt% to about 20 wt%, having an average diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, an average thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and an average aspect ratio greater than 2.0, wherein the average diameter is determined by transmission electron microscopy and the average thickness is determined by transmission electron microscopy,

[0226] The following general formula ( I Silver nanoplatelet comprising a surface stabilizer of );

[0227] ( I )

[0228] In the above formula,

[0229] Remaining R A is a C2-C4 alkyl group substituted with a hydroxyl group;

[0230] Remaining R B is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0231] Cat + is a general formula + NH 2 R C R D It is an ammonium cation of, and

[0232] Remaining R C is a C2-C4 alkyl group substituted with a hydroxyl group;

[0233] Remaining R D is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0234] b) b-1) About 45 weight% to about 80 weight% of alicyclic epoxide; or

[0235] b-2) A mixture of about 45% by weight to about 80% by weight of a cycloaliphatic epoxide and one or more cationic curable monomers;

[0236] c) One or more cationic photoinitiators;

[0237] d) A perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl;

[0238] e) About 3 weight% to about 12 weight% of a polyvinyl chloride copolymer containing at least 60 weight% of vinyl chloride; and optionally,

[0239] f) Up to approximately 25 wt% of organic solvent; the wt% is based on the total weight of the UV-Vis radiation cationic curable security ink. The UV-Vis radiation cationic curable security ink b-2) When containing a mixture of alicyclic epoxide and one or more cationic curable monomers in an amount of about 45% to about 80% by weight, it is preferable that the ratio between the total weight percentage of one or more cationic curable monomers and the weight percentage of the alicyclic epoxide be less than 1.4:1, preferably less than 1:1, and more preferably less than 0.9:1.

[0240] An alternative preferred embodiment according to the present invention relates to a UV-Vis radiation hybrid curable security ink for producing a security feature that exhibits blue when viewed under transmitted light and metallic yellow when viewed under incident light (i.e., an ink comprising both a cationic curable monomer and a radical curable monomer / oligomer), wherein the ink comprises the following:

[0241] a) As silver nanoplatelets of about 7.5 wt% to about 20 wt%, having an average diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, an average thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and an average aspect ratio greater than 2.0, wherein the average diameter is determined by transmission electron microscopy and the average thickness is determined by transmission electron microscopy,

[0242] The following general formula ( I Silver nanoplatelet comprising a surface stabilizer of );

[0243] ( I )

[0244] In the above formula,

[0245] Remaining R A is a C2-C4 alkyl group substituted with a hydroxyl group;

[0246] Remaining R B is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0247] Cat + is a general formula + NH 2 R C R D It is an ammonium cation of, and

[0248] Remaining R C is a C2-C4 alkyl group substituted with a hydroxyl group;

[0249] Remaining R D is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups;

[0250] b) b-3) A mixture of about 45 weight% to about 80 weight% of a cycloaliphatic epoxide and one or more radical-curable monomers and / or oligomers; or

[0251] b-4) A mixture of a cycloaliphatic epoxide, one or more cationic curable monomers, and one or more radical curable monomers and / or oligomers, in an amount of about 45% to about 80% by weight, preferably about 45% to about 65% by weight;

[0252] c) One or more cationic photoinitiators;

[0253] d) A perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl;

[0254] e)About 3 weight% to about 12 weight% of polyvinyl chloride copolymer containing at least 60 weight% of vinyl chloride;

[0255] g) One or more free radical photoinitiators; and optionally

[0256] f) Up to approximately 25 weight percent of organic solvent;

[0257] Weight % is based on the total weight of the UV-Vis radiation hybrid curable security ink. The hybrid ink claimed herein b-3) Where a mixture of alicyclic epoxide and one or more radical-curable monomers and / or oligomers comprises about 45 weight% to about 80 weight%, the ratio between the total weight% of one or more radical-curable monomers and / or oligomers and the weight% of the alicyclic epoxide is preferably less than 1.6:1, more preferably less than 1:1, and even more preferably less than 0.5:1. The hybrid ink claimed herein b-4) In the case of containing a mixture of alicyclic epoxide, one or more cationic curable monomers and one or more radical curable monomers and / or oligomers, of about 45% to about 80% by weight, preferably about 45% to about 65% by weight, the ratio between the total weight% of one or more radical curable monomers and / or oligomers and the sum of the weight% of alicyclic epoxide and the total weight% of one or more cationic curable monomers is preferably less than 1.6:1, more preferably less than 1:1, and even more preferably less than 0.5:1, and the ratio between the weight% of one or more cationic curable monomers and the weight% of alicyclic epoxides is preferably less than 1.4:1, more preferably less than 1:1, and even more preferably less than 0.9:1.

[0258] Advantageously, the UV-Vis radiation cation-curable security ink and the UV-Vis radiation hybrid-curable security ink claimed herein provide security features having improved mechanical resistance properties compared to security features known in the art obtained by UV radical-curable inks or solvent-based inks, particularly UV radical-curable inks or solvent-based inks containing a high concentration of silver nanoplatelets.

[0259] As is known to those skilled in the art, cationic curable monomers are cured by a cationic mechanism consisting of activation by UV-Vis light of one or more photoinitiators that release a cationic species, such as an acid, to form a cured binder, and then initiate the polymerization of the compound.

[0260] As is well known to those skilled in the art, a cycloaliphatic epoxide comprises at least one substituted or unsubstituted epoxycyclohexyl residue It is a cationic curable monomer containing . Preferably, the alicyclic epoxide described herein comprises at least one cyclohexane ring and at least two epoxide groups. More preferably, the alicyclic epoxide is of the following general formula ( V It is a compound of:

[0261] ( V )

[0262] In the above formula -L- represents a divalent group containing one or more atoms or a single bond. General formula ( V ) cycloaliphatic epoxides are (methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyl, s -Butyl, t - One or more linear or branched alkyl radicals containing 1 to 10 carbon atoms (such as butyl, hexyl, octyl, and decyl) and preferably (methyl, ethyl,n - Profile and i -Propyl) is optionally substituted by one or more linear or branched alkyl radicals containing 1 to 3 carbon atoms.

[0263] General formula ( V In ), 2 is -L- It may be a straight-chain or branched-chain alkylene group comprising 1 to 18 carbon atoms. Examples of straight-chain or branched-chain alkylene groups include, but are not limited to, methylene groups, methylmethylene groups, dimethylmethylene groups, ethylene groups, propylene groups, and trimethylene groups.

[0264] General formula ( V In ), 2 is -L- It may be a divalent alicyclic hydrocarbon group such as a 1,2-cyclopentylene group, a 1,3-cyclopentylene group, a cyclopentylidene group, a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, a 1,4-cyclohexylene group, and a cyclohexylidene group, or a cycloalkylidene group.

[0265] General formula ( V )at, -L- ... may be a divalent group comprising one or more oxygen-containing linkage groups, wherein the oxygen-containing linkage groups are selected from the group consisting of -C(=O)-, -OC(=O)O-, -C(=O)O-, and -O-. Preferably, the alicyclic epoxide is, -L- A general formula ( V It is a cycloaliphatic epoxide of ), and more preferably, as defined below, the general formula ( Va ), ( Vb ) or ( Vc It is a cycloaliphatic epoxide of:

[0266] ( Va )

[0267] In the above formula,

[0268] L 1 It may be the same or different in each case (methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyl, s -Butyl, t - A linear or branched alkyl radical containing 1 to 10 carbon atoms (such as butyl, hexyl, octyl, and decyl), preferably (methyl, ethyl, n - Profile and i - (like propyl) a linear or branched alkyl radical containing 1 to 3 carbon atoms;

[0269] L 2 It may be the same or different in each case (methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyl, s -Butyl, t - A linear or branched alkyl radical containing 1 to 10 carbon atoms (such as butyl, hexyl, octyl, and decyl), preferably (methyl, ethyl, n - Profile and i - (like propyl) a linear or branched alkyl radical containing 1 to 3 carbon atoms;

[0270] I 1 and I 2 are integers included independently between 0 and 9, preferably between 0 and 3;

[0271] ( Vb )

[0272] In the above formula,

[0273] L 1 It may be the same or different in each case (methyl, ethyl, n-profile, i -profile, n -Butyl, i -Butyl, s -Butyl, t - A linear or branched alkyl radical containing 1 to 10 carbon atoms (such as butyl, hexyl, octyl, and decyl), preferably (methyl, ethyl, n - Profile and i - (like propyl) a linear or branched alkyl radical containing 1 to 3 carbon atoms;

[0274] L 2 It may be the same or different in each case (methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyl, s -Butyl, t - A linear or branched alkyl radical containing 1 to 10 carbon atoms (such as butyl, hexyl, octyl, and decyl), preferably (methyl, ethyl, n - Profile and i - (like propyl) a linear or branched alkyl radical containing 1 to 3 carbon atoms;

[0275] I 1 and I 2 are integers included independently between 0 and 9, preferably between 0 and 3;

[0276] -L 3 - is a linear or branched divalent hydrocarbon group containing 1 to 10 carbon atoms, preferably 3 to 8, such as a single bond or an alkylene group including trimethylene, tetramethylene, hexamethylene, and 2-ethylhexylene, a cycloalkylene group such as a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, and a 1,4-cyclohexylene group, and a cyclohexylidene group;

[0277] ( Vc )

[0278] In the above formula,

[0279] L 1 It may be the same or different in each case, and methyl, ethyl, n - Profile and i - It is a linear or branched alkyl radical containing 1 to 3 carbon atoms, such as propyl;

[0280] L 2 It may be the same or different in each case, and methyl, ethyl, n - Profile and i - It is a linear or branched alkyl radical containing 1 to 3 carbon atoms, such as propyl;

[0281] I 1 and I 2 is an integer included between 0 and 9, preferably between 0 and 3, independently of each other.

[0282] General formula ( Va A preferred cycloaliphatic epoxide of ) includes, but is not limited to, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methyl-cyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, 3,4-epoxy-2-methyl-cyclohexylmethyl-3,4-epoxy-2-methyl-cyclohexanecarboxylate and 3,4-epoxy-4-methyl-cyclohexylmethyl-3,4-epoxy-4-methylcyclohexanecarboxylate.

[0283] General formula ( Vb The preferred cycloaliphatic epoxides of ) include, but are not limited to, bis(3,4-epoxycyclohexylmethyl)adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, bis(3,4-epoxycyclohexylmethyl)oxalate, bis(3,4-epoxycyclohexylmethyl)pimelate and bis(3,4-epoxycyclohexylmethyl)sebacate.

[0284] General formula ( Vc The preferred cycloaliphatic epoxide of ) is 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane.

[0285] Additional cycloaliphatic epoxides are (methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyl, s -Butyl, t - One or more linear or branched alkyl groups containing 1 to 10 carbon atoms (such as butyl, hexyl, octyl, and decyl), and preferably (methyl, ethyl, n - Profile and i - As with the propyl) optionally substituted with one or more linear or branched alkyl groups containing 1 to 3 carbon atoms, the following general formula ( VI-a ) cycloaliphatic epoxide and the following general formula ( VI-b It includes cycloaliphatic epoxides of ).

[0286] ( VI-a )

[0287] ( VI-b )

[0288] The cycloaliphatic epoxides described herein may be hydroxy modified or (meth)acrylate modified. Examples are commercially available as Cyclomer A400 (CAS: 64630-63-3) and Cyclomer M100 (CAS No.: 82428-30-6) by Daicel Corp., or as TTA 15 and TTA16 46 by TetraChem / Jiangsu.

[0289] One or more cationic curable monomers described herein are selected from the group consisting of vinyl ethers, prophenyl ethers, cyclic ethers other than alicyclic epoxides, lactones, cyclic thioethers, vinyl thioethers, prophenyl thioethers, hydroxyl-containing compounds, and mixtures thereof, preferably from the group consisting of vinyl ethers, cyclic ethers other than alicyclic epoxides, and mixtures thereof. Cyclic ethers other than alicyclic epoxides include epoxides other than alicyclic epoxides, oxetanes, and tetrahydrofurans. Preferably, the ratio between the total weight% of one or more cationic curable monomers and the weight% of alicyclic epoxides is less than 1.4:1, more preferably less than 1:1, most preferably less than 0.9:1, and particularly preferably less than 0.8:1.

[0290] Vinyl ethers are known in the art to promote curing and reduce tackiness, thereby limiting the risk of blocking and set-off when stacking printed sheets immediately after printing and curing. This also improves the physical and chemical resistance of printed security elements and enhances the flexibility and adhesion of the printed and cured ink layer to the substrate, making it particularly advantageous for printing on plastic and polymer substrates. Vinyl ethers also help reduce the viscosity of the ink during strong copolymerization with the ink vehicle. Preferred vinyl ethers for use in the security inks claimed herein include methyl vinyl ether, ethyl vinyl ether, n -Propyl vinyl ether, n -Butyl vinyl ether, Iso -Butyl vinyl ether, ethylhexyl vinyl ether, octadecyl vinyl ether, dodecyl vinyl ether, isopropyl vinyl ether, Burst -Butyl vinyl ether, Burst-Amyl vinyl ether, cyclohexyl vinyl ether, cyclohexanedimethanol monovinyl ether, cyclohexanedimethanol divinyl ether, 4-(vinyloxymethyl)cyclohexylmethyl benzoate, phenyl vinyl ether, methylphenyl vinyl ether, methoxyphenyl vinyl ether, 2-chloroethyl vinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, 1,6-hexanediol monovinyl ether, ethylene glycol divinyl ether, ethylene glycol monovinyl ether, 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, 4-(vinyloxy)butyl benzoate, bis[4-(vinyloxy)butyl]adipate, Bis[4-(vinyloxy)butyl]succinate, Bis[4-(vinyloxymethyl)cyclohexylmethyl]glutarate, 4-(vinyloxy)butyl stearate, Trimethylolpropane trivinyl ether, Propylene carbonate prophenylene ether, Diethylene glycol monovinyl ether, Diethylene glycol divinyl ether, Ethylene glycol butylvinyl ether, Dipropylene glycol divinyl ether, Triethylene glycol divinyl ether, Triethylene glycol methyl vinyl ether, Triethylene glycol monobutyl vinyl ether, Tetraethylene glycol divinyl ether, Poly(tetrahydrofuran) divinyl ether, Polyethylene glycol-520 methyl vinyl ether, Plurilol-E200 divinyl ether, Tris[4-(vinyloxy)butyl]trimellitate, Includes 1,4-bis(2-vinyloxyethoxy)benzene, 2,2-bis(4-vinyloxyethoxyphenyl)propane, bis[4-(vinyloxy)methyl]cyclohexyl]methyl]terephthalate, and bis[4-(vinyloxy)methyl]cyclohexyl]methyl]isophthalate. Suitable vinyl ethers are commercially sold by BASF under the names EVE, IBVE, DDVE, ODVE, BDDVE, DVE-2, DVE-3, CHVE, CHDM-di, and HBVE.One or more vinyl ethers described herein may be hydroxy-modified or (meth)acrylate-modified (e.g., VEEA of Nippon Shokubai, 2-(2-vinyloxyethoxy)ethyl acrylate (CAS: 86273-46-3)).

[0291] Oxetane is known in the art to promote curing and reduce tack, thereby limiting the risk of blocking and set-off when stacking printed sheets immediately after printing and curing. It also helps reduce the viscosity of the ink during strong copolymerization with the ink vehicle. Preferred examples of oxetane include trimethylene oxide, 3,3-dimethyloxetane, trimethylolpropane oxetane, 3-ethyl-3-hydroxymethyl oxetane, 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, 3,3-dicyclomethyl oxetane, 3-ethyl-3-phenoxymethyl oxetane, bis([1-ethyl(3-oxetanyl)]methyl) ether, 1,4-bis[3-ethyl-3-oxetanyl methoxy)methyl]benzene, and 3,3-dimethyl-2( p -methoxy-phenyl)-oxetane, 3-ethyl-[(tri-ethoxysilylpropoxy)methyl]oxetane, 4,4-bis(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl and 3,3-dimethyl-2( p It includes -methoxy-phenyl)oxetane. One or more oxetanes described herein may be hydroxy-modified or (meth)acrylate-modified (e.g., Lambson’s UVi-Cure S170 (CAS: 37674-57-0)).

[0292] The use of epoxides in UV-Vis radiation-curable inks helps not only to reduce the viscosity of the ink during strong copolymerization with the ink vehicle, but also to promote curing and reduce tackiness. Preferred examples of epoxides other than alicyclic epoxides, such as those described herein, include cyclohexanedimethanol diglycidyl ether, poly(ethylene glycol) diglycidyl ether, poly(propylene glycol) diglycidyl ether, butanediol diglycidyl ether, hexanediol diglycidyl ether, bisphenol-A diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, pentaerythritol tetraglycidyl ether, butyl glycidyl ether, p - Burst -Butylphenylglycidyl ether, hexadecyl glycidyl ether, 2-ethyl-hexyl glycidyl ether, octyl glycidyl ether, decyl glycidyl ether, dodecyl glycidyl ether, tetradecyl glycidyl ether, C 12 / C 14 -alkyl glycidyl ether, C 13 / C 15 - Alkyl glycidyl ethers and mixtures thereof are included but not limited thereto. Epoxides other than suitable alicyclic epoxides are commercially sold by EMS Griltech under the trademark Grilonit® (e.g., Grilonit® V51-63 or RV 1806).

[0293] The radical-curable monomers described herein are selected from the group consisting of mono(meth)acrylate, di(meth)acrylate, tri(meth)acrylate, tetra(meth)acrylate, and mixtures thereof, preferably from the group consisting of tri(meth)acrylate, tetra(meth)acrylate, and mixtures thereof. In the context of the present invention, the term “(meth)acrylate” refers to acrylate as well as the corresponding methacrylate.

[0294] Preferred examples of mono(meth)acrylates include the following mixtures as well as 2(2-ethoxyethoxy)ethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, C 12 / C 14 Alkyl (meth)acrylate, C 16 / C 18 Alkyl (meth)acrylate, Caprolactone (meth)acrylate, Cyclic Trimethylolpropane Formal (meth)acrylate, Nonylphenol (meth)acrylate, Isobornyl (meth)acrylate, Isodecyl (meth)acrylate, Lauryl (meth)acrylate, Stearyl (meth)acrylate, Octyldecyl (meth)acrylate, Tridecyl (meth)acrylate, Methoxypoly(ethylene glycol) (meth)acrylate, Polypropylene glycol (meth)acrylate, Tetrahydrofurfuryl (meth)acrylate, 1,3-Butylene Glycol Di(meth)acrylate, 1,4-Butanediol Di(meth)acrylate, 1,6-Hexanediol Di(meth)acrylate, 3-Methyl-1,5-Pentanediol Di(meth)acrylate, It also includes alkoxylated di(meth)acrylates and esterdiol di(meth)acrylates.

[0295] Preferred examples of di(meth)acrylates include the following mixtures as well as bisphenol A di(meth)acrylate, alkoxylated bisphenol A di(meth)acrylate (such as ethoxylated and propoxylated), bisphenol A diglycidyl ether di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and tricyclodecane dimethanol di(meth)acrylate.

[0296] Preferred examples of tri(meth)acrylates include, in addition to the following mixtures, trimethylolpropane tri(meth)acrylate, alkoxylated trimethylolpropane tri(meth)acrylate (e.g., ethoxylated and propoxylated), alkoxylated glycerol tri(meth)acrylate (e.g., ethoxylated and propoxylated), pentaerythritol tri(meth)acrylate, alkoxylated pentaerythritol tri(meth)acrylate, and alkoxylated pentaerythritol tri(meth)acrylate (e.g., ethoxylated and propoxylated).

[0297] Preferred examples of tetra(meth)acrylates include ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, alkoxylated pentaerythritol tetra(meth)acrylate (such as ethoxylated and propoxylated ones), and mixtures thereof, preferably selected from the group consisting of ditrimethylolpropane tetra(meth)acrylate and alkoxylated pentaerythritol tetra(meth)acrylate as well as the following mixtures.

[0298] As used herein, the term “radical-curable oligomer” refers to a radical-curable (meth)acrylate oligomer that may be branched or essentially linear and may have terminal and / or pendant (meth)acrylate functional groups. The radical-curable oligomer is preferably selected from the group consisting of (meth)acrylate oligomers, urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, polyether-based (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, and mixtures thereof, more preferably polyester (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, and mixtures thereof.

[0299] Suitable examples of epoxy (meth)acrylate oligomers include, but are not limited to, aliphatic epoxy (meth)acrylate oligomers, in particular mono(meth)acrylate, di(meth)acrylate, and tri(meth)acrylate, and aromatic epoxy (meth)acrylate oligomers. Suitable examples of aromatic epoxy (meth)acrylate oligomers include, for example, alkoxylated bisphenol-A mono(meth)acrylate, alkoxylated bisphenol-A di(meth)acrylate, and alkoxylated bisphenol-A tri(meth)acrylate, preferably alkoxylated bisphenol-A di(meth)acrylate (as ethoxylated or propoxylated), as well as alkoxylated bisphenol-A (meth)acrylate oligomers such as bisphenol-A mono(meth)acrylate, bisphenol-A di(meth)acrylate, and bisphenol-A tri(meth)acrylate.

[0300] The security ink claimed in this specification is c) It contains one or more cationic photoinitiators. Preferably, the amount of one or more cationic photoinitiators in the UV-Vis radiation cationic curable security ink claimed herein (i.e., an ink containing only cationic curable monomers and not radical curable monomers) is about 1 wt% to about 10 wt%, preferably about 1.1 wt% to about 8 wt%, more preferably about 1.1 wt% to about 6 wt%, where the wt% is based on the total weight of the UV-Vis radiation cationic curable ink. Preferably, the amount of one or more cationic photoinitiators in the UV-Vis radiation hybrid curable security ink claimed herein (i.e., an ink containing both cationic curable monomers and radical curable monomers) is 1 wt% to about 6 wt%, where the wt% is based on the total weight of the UV-Vis radiation cationic curable ink.

[0301] One or more cationic photoinitiators described herein (also referred to in the art as photo-acid generators) are preferably onium salts selected from the group consisting of azonium salts, oxonium salts, iodonium salts, sulfonium salts and mixtures thereof, more preferably oxonium salts, iodonium salts, sulfonium salts and mixtures thereof, and even more preferably sulfonium salts, iodonium salts and mixtures thereof.

[0302] The iodine salts described herein have a cationic moiety and an anionic moiety, wherein the anionic moiety is preferably BF4 - , B(C6F5)4 - , PF6 - , AsF6 - , SbF6 - or CF3SO3 - , more preferably SbF6 - The cationic moiety is preferably an aromatic iodinium ion, more preferably an iodinium ion containing two aryl groups, wherein the two aryl groups may be independently substituted with one or more alkyl groups (e.g., methyl, ethyl, isobutyl, tertbutyl), one or more alkoxy groups, one or more nitro groups, one or more halogen-containing groups, one or more hydroxyl groups, or a combination thereof, preferably one or more alkyl groups. Iodium salts particularly suitable for the present invention are commercially available under the names DEUTERON UV 1240, DEUTERON UV 1242, DEUTERON UV 2257, DEUTERON UV 1250, and DEUTERON UV 3100, all available from DEUTERON; OMNICAT 250, OMNICAT 440, and OMNICAT 445, all available from IGM Resins; and SpeedCure 937, SpeedCure 938, and SpeedCure 939, all available from Lambson.

[0303] The sulfonium salts described herein have a cationic moiety and an anionic moiety, wherein the anionic moiety is preferably BF4 - , B(C6F5)4 - , PF6 - , (PF 6-h (C j F 2j-1 ) h ) - ( h is an integer from 1 to 5, and j is an integer from 1 to 4), AsF6 - , SbF6 - , CF3SO3 - , perfluoroalkyl sulfonate or pentafluorohydroxyantimonate, more preferably SbF6 -The cationic moiety is preferably an aromatic sulfonium ion, more preferably a sulfonium ion comprising two or more aryl groups, wherein the two or more aryl groups may be independently substituted with one or more alkyl groups (e.g., methyl, ethyl, isobutyl, tertbutyl, etc.), one or more alkoxy groups, one or more aryloxy groups, one or more halogen-containing groups, one or more hydroxyl groups, or a combination thereof. Suitable examples of sulfonium ions comprising two or more aryl groups include, but are not limited to, triarylsulfonium ions, diphenyl[4-(phenylthio)phenyl]sulfonium ions, bis[4-(diphenylsulfonio)phenyl]sulfonium ions, triphenylsulfonium ions, and tris[4-(4-acetylphenyl)sulfanylphenyl]sulfonium ions. Examples of sulfonium salts particularly suitable for the present invention are commercially available under the names SpeedCure 976, SpeedCure 976D, and SpeedCure 992, all available from Lambson; ESACURE 1187, OMNICAT 270, OMNICAT 320, OMNICAT 432, and OMNICAT 550, all available from IGM Resins; and DoubleCure 1176, DoubleCure 1190, and DoubleCure 1172, all available from DoubleBond.

[0304] The oxonium salts described herein have a cationic moiety and an anionic moiety, wherein the anionic moiety is preferably BF4 - , B(C6F5)4 - , PF6 - , AsF6 - , SbF6 - or CF3SO3 - , more preferably BF4 -The cationic moiety is preferably an aromatic oxonium ion, more preferably a pyrillium ion substituted with one or more aryl groups, wherein the one or more aryl groups may be independently substituted with one or more alkyl groups (e.g., methyl, ethyl, isobutyl, tertbutyl, etc.), one or more alkoxy groups, one or more nitro groups, one or more halogen groups, one or more hydroxyl groups, or a combination thereof. An oxonium salt particularly suitable for the present invention is 2,4,6-triphenylpyrillium tetrafluoroborate.

[0305] Other examples of useful cationic 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, by J.V. Crivello & K. Dietliker (edited by G. Bradley and published by John Wiley & Sons in 1998 in collaboration with SITA Technology Limited).

[0306] In addition, the hybrid security ink claimed in this specification g) It contains one or more free radical photoinitiators. Preferably, the amount of one or more free radical photoinitiators in the UV-Vis radiation hybrid curable ink described herein is about 1% by weight to about 6% by weight, and the percentage is based on the total weight of the UV-Vis radiation hybrid curable ink.

[0307] One or more free radical photoinitiators as used in this specification are preferably selected from the group consisting of hydroxyketones (e.g., alpha-hydroxyketones), alkoxyketones (e.g., alpha-alkoxyketones), acetophenones, benzophenones, ketosulfones, benzyl ketals, benzoin ethers, phosphine oxides, phenylglyoxylates, thioxantones, and mixtures thereof, more preferably phosphine oxides, hydroxyketones, thioxantones, and mixtures thereof.

[0308] Suitable alpha-hydroxyketones include, but are not limited to, (1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one), 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-hydroxy-2-methyl-1-(4-tert-butyl)phenylpropan-1-one, 2-hydroxy-1-[4-[[4-(2-hydroxy-2-methylpropanoyl)phenyl]methyl]phenyl]-2-methylpropan-1-one, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropanoyl)phenoxy]phenyl]-2-methylpropan-1-one and oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone]. does not.

[0309] Suitable acetophenones include, but are not limited to, 2,2-diethoxyacetophenone and 2-methoxy-2-phenylacetophenone.

[0310] Suitable benzophenones include, but are not limited to, benzophenone, polymeric benzophenone derivatives, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-phenylbenzophenone, 4-chlorobenzophenone, methyl-2-benzoylbenzoate, 4-(4-methylphenylthio)benzophenone, 4-hydroxybenzophenone laurate, and mixtures of 50% benzophenone and 50% 1-hydroxycyclohexylphenyl ketone.

[0311] Suitable ketosulfones include, but are not limited to, 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one.

[0312] Suitable benzyl ketal includes, but is not limited to, 2,2-dimethoxy-2-phenylacetophenone.

[0313] Suitable benzoin ethers include, but are not limited to, 2-ethoxy-1,2-diphenylethanolone, 2-isopropoxy-1,2-diphenylethanolone, 2-isobutoxy-1,2-diphenylethanolone, 2-butoxy-1,2-diphenylethanolone, 2,2-dimethoxy-1,2-diphenylethanolone and 2,2-diethoxyacetophenone.

[0314] Suitable phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl phenyl(2,4,6-trimethylbenzoyl)phenylphosphine oxide, phenyl-bis(2,4,6-trimethylbenzoyl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, substituted acyl-phosphine oxides, mixtures of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and 2-hydroxy-2-methylpropiophenone, mixtures of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 2-hydroxy-2-methylpropiophenone, mixtures of ethyl(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2-hydroxy-2-methylpropiophenone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine. It includes, but is not limited to, a mixture of oxide and ethyl phenyl(2,4,6-trimethylbenzoyl)phenylphosphinate.

[0315] Suitable thioxantones include, but are not limited to, 2-methyl thioxantone, 2,4-diethyl thioxantone, 2-isopropyl thioxantone, 1-chloro-4-propoxythioxantone and polymeric thioxantone derivatives.

[0316] Suitable phenylglyoxylates include, but are not limited to, methyl benzoyl formate, 2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl 2-oxo-2-phenylacetate and a mixture of 2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl 2-oxo-2-phenylacetate and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester.

[0317] Preferably, one or more free radical photoinitiators are phosphine oxides as described herein, and more preferably, a mixture of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and ethyl phenyl(2,4,6-trimethylbenzoyl)phenylphosphinate.

[0318] The UV-Vis radiation-curable security ink described in this specification d) It contains a perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl, preferably two or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl. Surprisingly, using a perfluoropolyether functionalized with one or more, preferably two or more, functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl as a surfactant in the UV-Vis radiation-curable ink described herein has been found to be essential for producing a security feature that exhibits a metallic yellow color when viewed under incident light. For example Table 3c and Table 4c As demonstrated by, only UV-Vis radiation-curable inks containing a perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl provide the security feature of exhibiting a metallic yellow color when viewed under incident light. UV-Vis radiation-curable inks without surfactants (e.g., ink C8UV-Vis radiation-curable inks comprising ) or perfluoropolyether surfactants without functional groups (e.g., ink C1 UV-Vis radiation-curable inks containing a surfactant without a perfluoropolyether backbone (e.g., ink) C2-C7 ) exhibits a brown to dark brown color that does not attract the attention of the general public when reflected, and therefore is not suitable for dichroic security features to secure valuable documents.

[0319] A perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl comprises a perfluoropolyether backbone and one or more, preferably two or more, terminal functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl, and has an average molecular weight (M nIt is characterized by having a value of less than about 2000 [g / mol]. As used herein, the perfluoropolyether backbone represents a residue of a perfluoropolyether polymer comprising randomly distributed repeating units selected from perfluoromethyleneoxy (-CF2O-) and perfluoroethyleneoxy (-CF2-CF2O-). The perfluoropolyether residue is connected directly to the terminal functional group or through a spacer selected from straight-chain or branched-chain hydrocarbon groups containing one or more urethane groups or one or more amide groups, and optionally one or more cyclic moiety comprising a saturated cyclic moiety (e.g., cyclohexylene) and an aromatic cyclic moiety (e.g., phenylene), which is fluorinated at the carbon atom connecting the spacer to the perfluoropolyether residue, and optionally a spacer comprising one or more urethane groups or one or more amide groups, and optionally one or more cyclic moiety comprising a saturated cyclic moiety (e.g., cyclohexylene) and an aromatic cyclic moiety (e.g., phenylene). Preferably, the perfluoropolyether surfactant is functionalized with one or more hydroxyl functional groups.

[0320] In a further preferred embodiment, a perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl has an average molecular weight of about 1200 [g / mol] to about 2000 [g / mol] according to the following general formula ( VII It is a compound of ).

[0321] ( VII )

[0322] In the above formula,

[0323] f and eare integers selected independently from 1, 2, and 3;

[0324] FG 1 and FG 2 is -OH, -OC(O)CH=CH2, -OC(O)C(CH3)=CH2 and -Si(OR 20 A terminal functional group independently selected from the group consisting of )3;

[0325] R 20 is a C1-C4 alkyl group;

[0326] -S 1 - is a single bond or

[0327] , , , and Represents a spacer selected from;

[0328] -J 1 - silver

[0329] , , , and Selected from,

[0330] j 1 is an integer included between 1 and 12, preferably between 4 and 10;

[0331] L 5 may be the same or different in each case and is a linear or branched alkyl radical containing 1 to 10 carbon atoms (e.g., methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyl s -Butyl, t-butyl, hexyl, octyl, and decyl), and preferably linear or branched alkyl radicals containing 1 to 3 carbon atoms (e.g., methyl, ethyl, n - Profile and i -Profile) and;

[0332] L 6 It may be the same or different in each case and is a linear or branched alkyl radical containing 1 to 10 carbon atoms (e.g., methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyl s -Butyl, t -butyl, hexyl, octyl, and decyl), and preferably linear or branched alkyl radicals containing 1 to 3 carbon atoms (e.g., methyl, ethyl, n - Profile and i -Profile) and;

[0333] I 5 and I 6 are integers included independently between 0 and 4, preferably between 0 and 1;

[0334] -J 3 - is selected from -O-, -CH2-, -CH(CH3)- and -C(CH3)2-;

[0335] -J 2 - Is

[0336] , and Selected from;

[0337] a is an integer included between 1 and 6, preferably between 1 and 3;

[0338] b is an integer included between 1 and 6, preferably between 2 and 4;

[0339] -S 2 - is a single combination or

[0340] , , , and Represents a spacer selected from;

[0341] -J 4 - Is

[0342] , , , and Selected from;

[0343] j 4 is an integer included between 1 and 12, preferably between 4 and 10;

[0344] L 7 It may be the same or different in each case and is a linear or branched alkyl radical containing 1 to 10 carbon atoms (e.g., methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyl s -Butyl, t -butyl, hexyl, octyl, and decyl), and preferably linear or branched alkyl radicals containing 1 to 3 carbon atoms (e.g., methyl, ethyl, n - Profile and i -Profile) and;

[0345] L 8 It may be the same or different in each case and is a linear or branched alkyl radical containing 1 to 10 carbon atoms (e.g., methyl, ethyl, n -profile, i -profile, n -Butyl, i -Butyls -Butyl, t -butyl, hexyl, octyl, and decyl), and preferably linear or branched alkyl radicals containing 1 to 3 carbon atoms (e.g., methyl, ethyl, n - Profile and i -Profile) and;

[0346] I 7 and I 8 are integers included independently between 0 and 4, preferably between 0 and 1;

[0347] -J 6 - is selected from -O-, -CH2-, -CH(CH3)- and -C(CH3)2-;

[0348] -J 5 - Is

[0349] , and Selected from;

[0350] r is an integer included between 1 and 6, preferably between 1 and 3;

[0351] w is an integer included between 1 and 6, preferably between 2 and 4;

[0352] s and t is a general formula ( VII It is an integer selected such that the average molecular weight of the compound is about 1200 [g / mol] to about 2000 [g / mol].

[0353] Preferably, general formula ( VII )at, FG 1 and FG 2 represents -OC(O)CH=CH2 or -OC(O)C(CH3)=CH2 independently of each other;

[0354] -S 1 - silver Represents, b has the meaning defined in this specification;

[0355] -S 2 - Is Represents, w has the meaning defined in this specification.

[0356] Also preferably, general formula ( VII )at, FG 1 and FG 2 represents -OH;

[0357] -S 1 - is a single bond or Represents, a has the meaning defined in this specification;

[0358] -S 2 - is a single combination or Represents, r ...has the meaning defined in this specification; o and r The sum of is between 3 and 9.

[0359] Also preferably, general formula ( VII )at, FG 1 and FG 2 is -Si(OR 20 Representing )3;

[0360] R 20 is a C1-C4 alkyl group, preferably an ethyl group;

[0361] -S 1 - silver Representing, b has the meaning defined in this specification;

[0362] -S 2 - Is Representing, w has the meaning defined in this specification. Accordingly, a preferred perfluoropolyether surfactant is the following general formula ( VII-a It is a compound of:

[0363] ( VII-a )

[0364] In the above formula,

[0365] b and w is an integer included between 1 and 6, preferably between 2 and 4;

[0366] s is an integer between 2 and 6;

[0367] q is an integer between 2 and 4.

[0368] Particularly suitable examples of perfluoropolyether surfactants for the present invention, functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl, are commercially available from Solvay under the names Fluorolink® E10H, Fluorolink® MD700, Fluorolink® AD1700, Fluorolink® E-series, and Fluorolink® S10. The UV-Vis radiation-curable security ink of the present invention preferably comprises about 0.025 weight% to about 5 weight% of a perfluoropolyether surfactant, where weight% is based on the total weight of the UV-Vis radiation-curable security ink.

[0369] The UV-Vis radiation-curable security ink claimed in this specification e)It contains about 3% to about 12% by weight of a polyvinyl chloride copolymer containing at least 60% by weight of vinyl chloride, preferably at least 63% by weight of vinyl chloride. UV-Vis radiation-curable security inks that do not contain polyvinyl chloride copolymers are not suitable for use in producing security features that have a color that does not attract attention, such as brown or dark brown, and provide a low saturation value C* when viewed in incident light, and consequently exhibit a metallic yellow color in incident light.

[0370] It is preferable that the polyvinyl chloride copolymer contains up to 90 weight percent of vinyl chloride.

[0371] Preferably, a polyvinyl chloride copolymer containing at least 60 weight% of vinyl chloride is present in the security ink claimed herein in an amount of about 4.9 weight% to about 11.6 weight%, and most preferably about 6 weight% to about 8.6 weight%, with the weight% based on the total weight of the UV-Vis radiation-curable ink.

[0372] Preferably, the polyvinyl chloride copolymer is selected from the group consisting of vinyl chloride-vinyl acetate copolymers, vinyl chloride-hydroxyalkyl acrylate copolymers such as vinyl chloride-2-hydroxypropyl acrylate copolymer, and vinyl chloride-hydroxyalkyl acrylate-Z-alkylenedioic acid, dialkyl ester copolymers such as vinyl chloride-2-hydroxypropyl acrylate-2-butenediioic acid(Z)-, dibutyl ester copolymer. The average molecular weight of the polyvinyl chloride copolymer, determined by size-exclusion chromatography using polystyrene as a standard and tetrahydrofuran as a solvent, is preferably 3 × 10⁻⁶. 4 g / mol to about 8 x 10⁻⁶ 4It is between g / mol. Particularly suitable examples of polyvinyl chloride copolymers for the present invention are commercially available from Wacker under the names Vinnol® H14 / 36, Vinnol® E22 / 48A, Vinnol® E15 / 40A and Vinnol® H40 / 50.

[0373] The UV-Vis radiation-curable security ink claimed in this specification f) It may contain up to about 25 weight percent of an organic solvent, and the weight percent is based on the total weight of the UV-Vis radiation-curable ink. The boiling point of the solvent is greater than 100°C. Suitable organic solvents used in the UV-Vis radiation-curable ink described herein include, but are not limited to, the following: ethyl-3-ethoxypropionate, 2-methoxy-1-methylethyl acetate, propylene glycol monomethyl ether, cyclopentanone, cyclohexanone, n - Butanol, cyclohexanol, ethylene carbonate, propylene carbonate, butylene carbonate, and mixtures thereof.

[0374] In a preferred embodiment according to the present invention, the UV-Vis radiation-curable security ink is solvent-free. The use of solvent-free ink in the industrial printing process of value documents is receiving high interest because it generally prevents the release of volatile organic compounds that have a negative impact on the environment and are harmful to human health.

[0375] The UV-Vis radiation-curable security inks claimed herein may further comprise one or more photosensitizers in combination with one or more photoinitiators described herein for efficient curing. Suitable examples of photosensitizers are known to those skilled in the art (e.g., Industrial Photoinitiators, WA Green, CRC Press, 2010, Table 8.1, page 170). Preferred photosensitizers are those capable of achieving efficient and rapid curing with a UV-LED light source, such as thioxantone derivatives, anthracene derivatives, and naphthalene derivatives (e.g., 9,10-diethoxyanthracene sold as Anthracure UVS-1101 by Kawasaki Kasei Chemicals Ltd and 9,10-dibutyloxyanthracene sold as Anthracure UVS-1331) and titanocene derivatives (e.g., Irgacure 784 sold by BASF). Particularly preferred are thioxantone derivatives including, but not limited to, isopropyl-thioxantone (ITX), 1-chloro-2-propoxy-thioxantone (CPTX), 2-chloro-thioxantone (CTX), and 2,4-diethyl-thioxantone (DETX) and mixtures thereof. Alternatively, thioxantone photosensitizers may be used in the form of oligomers or polymers (e.g., Omnipol TX sold by IGM Resins, Genopol* TX-2 sold by Rahn, or Speedcure 7010 sold by Lambson). Where present, one or more photosensitizers are present in an amount of about 0.1 wt% to about 2 wt%, more preferably about 0.2 wt% to about 1 wt%, with the wt% being based on the total weight of the UV-Vis radiocurable ink.

[0376] The UV-Vis radiation-curable ink claimed in this specification may additionally include one or more antifoaming agents in an amount of less than about 2 weight percent, preferably less than about 1 weight percent.

[0377] Another aspect according to the present invention relates to a method for manufacturing a security feature for securing a value document, wherein the security feature exhibits blue when viewed in transmitted light and metallic yellow when viewed in incident light, and the method comprises the following steps:

[0378] A) Preferably, a step of providing an ink layer by printing the UV-Vis radiation-curable security ink claimed herein by screen printing, rotogravure, or flexography onto a transparent or partially transparent area of ​​a substrate of a value document; and

[0379] B) step A) A step of UV-Vis curing the ink layer obtained from to form security features.

[0380] The original manufacturing method claimed herein enables access to security features that exhibit metallic yellow in incident light and blue, particularly intense blue to very intense blue, in a single printing step. As used herein, the term “printing” refers to any printing process suitable for printing the UV-Vis radiation-curable ink described herein onto a substrate of a value document. In particular, the term “printing” refers to a printing process selected from the group consisting of: screen printing, rotogravure, flexography, pad printing, inkjet printing, and spray printing. Preferably, the UV-Vis radiation-curable security ink is printed onto a transparent or partially transparent area of ​​the substrate of a value document by screen printing, rotogravure, or flexography, more preferably by screen printing.

[0381] As used herein, “transparent or partially transparent area of ​​the substrate of the value document” refers to an area of ​​the substrate of the value document, characterized in that the area has an average transmittance in a visible range of at least 50%, preferably at least 70%, and more preferably at least 90%. The transparent or partially transparent area of ​​the substrate and the remaining area of ​​the substrate may be made of the same material or different materials. Removing one or more layers in a multilayer structure, or applying a transparent or partially transparent material to a hole in the substrate made of a material different from the transparent or partially transparent material, provides a value document substrate in which the transparent or partially transparent area of ​​the substrate and the remaining area of ​​the substrate are made of different materials.

[0382] Materials for inscribing value documents include, but are not limited to, fibrous materials such as paper or cellulose, paper-containing materials, plastics and polymers, composite materials, and mixtures or combinations thereof. Common paper, paper-like, or other fibrous materials are made of various fibers including, but not limited to, 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, whereas wood pulp is generally used for security documents that are not banknotes. Common examples of plastics and polymers include polyolefins such as polypropylene (PP), including polystyrene, polycarbonate, polyethylene (PE), and biaxially oriented polypropylene (BOPP); polyamides (PA); polyesters such as poly(ethylene terephthalate) (PET); and poly(ethylene glycol- coIt includes polyethylene terephthalate glycol-modified (PETG) and polyvinyl chloride (PVC), comprising -1,4-cyclohexanedimethanol terephthalate, poly(1,4-butylene terephthalate) (PBT), and poly(ethylene 2,6-naphthoate) (PEN). General examples of composite materials include, but are not limited to, multilayer structures or laminates of paper and at least one plastic or polymer material as described above. Materials suitable for transparent or partially transparent areas of the substrate include polyolefins such as polystyrene, polycarbonate, polyethylene (PE), and polypropylene (PP), including biaxially oriented polypropylene (BOPP); polyamides (PA); polyesters such as poly(ethylene terephthalate) (PET); and poly(ethylene glycol- co Polyethylene terephthalate glycol-modified (PETG) and polyvinyl chloride (PVC) including 1,4-cyclohexanedimethanol terephthalate, poly(1,4-butylene terephthalate) (PBT), and poly(ethylene 2,6-naphthoate) (PEN), but not limited thereto. Transparent or partially transparent areas of the value document may have a primer layer on top of where the UV-Vis radiation-curable ink is printed. The primer layer can be obtained by UV-Vis curing a varnish containing all components of the UV-Vis radiation-curable ink described herein, excluding silver nanoplatelets.

[0383] Steps of the original manufacturing method claimed in this specification B) In, step A)The ink layer obtained is exposed to UV-Vis curing to form a security feature. As used herein, the term “UV-Vis curing” refers to the radiation curing of an ink layer by photopolymerization under the influence of irradiation having a wavelength component in UV or the visible part of the UV and electromagnetic spectrum (generally 100 nm to 800 nm, preferably 150 to 600 nm, more preferably 200 to 400 nm). Cationic curable monomers are cured by a cationic mechanism consisting of UV-Vis light activation of one or more photoinitiators that release cationic species, such as acids, to form a cured binder and subsequently initiate the polymerization of the compound. Radical curable monomers and oligomers are cured by a free radical mechanism consisting of UV-Vis light activation of one or more photoinitiators that release free radicals and subsequently initiate the polymerization process. Optionally, one or more photosensitizers may be present. The photosensitive material is activated by one or more wavelengths emitted by a UV-Vis light source and reaches an excited state. The photosensitive material in the excited state transfers energy to one or more photoinitiators (in free radical polymerization) or electrons (in cationic polymerization). Both processes subsequently initiate the polymerization process.

[0384] Preferably, step B) is a step A)The method comprises the step of exposing the ink layer obtained from to UV-Vis light emitted by a UV-Vis light source selected from the group consisting of: a mercury lamp, preferably a medium-pressure mercury lamp, a UV-LED lamp, and a sequence thereof. A typical sequence includes using one or more UV-LED lamps to partially cure the UV-Vis radiation composition in the first step and using one or more medium-pressure mercury lamps in the second step. Mercury lamps advantageously emit at a wide range of wavelengths within the UV-A, UV-B, and UV-C ranges. Thus, various photoinitiators or combinations of photoinitiators / photosensitive materials can be selected having absorption spectra that match at least one emission band of the mercury lamp. Since UV-LEDs have a more limited wavelength range, only a limited selection of photoinitiators or combinations of photoinitiators / photosensitive materials is sufficiently efficient at industrial printing speeds. On the other hand, UV-LEDs are less expensive, require less energy (in particular, require a much less demanding thermal dissipation system), do not tend to form ozone, and have a much longer lifespan.

[0385] To provide a value document having resistance to soil and / or to protect security features from physical and chemical attacks of the environment, the manufacturing method claimed herein preferably comprises the step B) The following steps performed thereafter C) and D) Includes additionally:

[0386] C) Preferably, a step of forming a varnish layer by applying a curable protective varnish onto a substrate by a printing process;

[0387] D) step C) A step of curing the varnish layer obtained from to form a protective coating.

[0388] step C)Examples of suitable hardening protective varnishes used in and / or examples of methods for applying a curable protective varnish onto a substrate and curing the varnish layer are described in International Patent Application Publication No. WO2020234211A1, International Patent Application Publication No. WO2013127715A2 and International Patent Application Publication No. WO2014067715A1.

[0389] Preferably, the value document is selected from banknotes, certificates, tickets, checks, vouchers, financial stamps, contracts, identification documents such as passports, ID cards, visas, and driver's licenses, bank cards, credit cards, transaction cards, access documents and cards, admission tickets, public transport tickets, academic diplomas, and academic titles. More preferably, the value document is a banknote. The security ink claimed herein may also be used to manufacture security features directly on the value product. The term “value product” refers to packaging materials that can be protected against counterfeiting and / or piracy to guarantee the contents of the packaging, such as genuine drugs, for example, particularly packaging materials for the pharmaceutical, cosmetic, electronic products, or food industries.

[0390] Examples

[0391] The present invention is now described in more detail with reference to non-limiting embodiments. The following embodiments E1-E26 and comparative example C1-C8 This specification provides a more detailed description of the manufacturing of UV-Vis radiation-curable screen printing security ink and the optical properties of the security features obtained therefrom.

[0392] A. Analytical Method

[0393] A-1. UV-Vis Spectroscopy

[0394] The UV-Vis spectrum of the dispersion was recorded on a Varian Cary 50 UV-Vis spectrophotometer at dispersion concentrations that achieve an optical density of 0.3 to 1.5 in an optical path of 1 cm.

[0395] A-2. TEM Analysis

[0396] TEM analysis of the dispersions was performed in bright-field mode on a Zeiss EM 910 instrument at an e-beam acceleration voltage of 100 kV. At least two representative images at different magnifications were recorded to characterize the dominant particle morphology for each sample.

[0397] The average diameter of the silver nanoplatelets was determined by transmission electron microscopy (TEM) using Fiji image analysis software based on measurements of at least 300 randomly selected silver nanoplatelets oriented parallel to the plane of the transmission electron microscopy (TEM) image, and the diameter of the silver nanoplatelets is the maximum dimension of the silver nanoplatelets oriented parallel to the plane of the transmission electron microscopy (TEM) image.

[0398] The average thickness of the silver nanoplatelets was determined by transmission electron microscopy (TEM) based on manual measurements of at least 50 randomly selected silver nanoplatelets oriented perpendicular to the plane of the TEM image, and the thickness of the silver nanoplatelets is the maximum thickness of the silver nanoplatelets.

[0399] B. Preparation and Characterization of Ag Nanoplate Dispersions D1 and D2

[0400] B-1. Synthesis of Raw Materials

[0401] In a 1 L double-walled glass reactor equipped with an anchor stirrer, 365 g of deionized water was cooled to +2°C. 13.62 g of sodium borohydride was added, and the mixture was cooled to -1°C while stirring at 250 revolutions per minute (RPM) (Solution A).

[0402] In a 0.5 L double-walled glass reactor equipped with an anchor stirrer, 132 g of deionized water and 4.8 g of MPEG-5000-thiol were mixed, and the mixture was stirred at room temperature for 10 minutes. 72 g of the product of Example A3 of WO2006074969 was added, and the resulting mixture was stirred further at room temperature for 10 minutes to homogenize it. A solution of 30.6 g of silver nitrate dissolved in 30 g of deionized water was added all at once, and the mixture was stirred for 10 minutes to produce an orange-brown viscous solution. After adding 96 g of deionized water to this solution, 3 g of Struktol SB 2080 antifoaming agent pre-dispersed in 36 g of deionized water was added. The resulting mixture was cooled to 0°C while stirring at 250 RPM (Solution B).

[0403] Subsequently, solution B was injected into solution A below the liquid surface through a cooled (0°C) dosing tube using a peristaltic pump at a constant rate over 2 hours to produce a dispersion of spherical silver nanoplatelets. During pumping, solution A was stirred at 250 RPM.

[0404] After the injection was completed, the reaction mixture was heated to +5°C within 15 minutes, and a solution of 862 mg of KCl dissolved in 10 g of deionized water was added all at once, followed by the addition of 9.6 g of ethylenediaminetetraacetic acid (EDTA) in four portions at 10-minute intervals.

[0405] After adding the final amount of EDTA, the reaction mixture was stirred at +5°C for 15 minutes, then heated to 35°C over 30 minutes, and stirred at this temperature for 1 hour. At this time, hydrogen release was completed.

[0406] 30 mL of a 30 wt% ammonia solution dissolved in water was added, followed by the addition of 5.76 g of solid NaOH, and the mixture was stirred at 35°C for 15 minutes. Subsequently, 180 mL of a 50 wt% hydrogen peroxide solution dissolved in water was injected into the reaction mixture below the liquid surface at a constant rate using a peristaltic pump over 4 hours while stirring at 250 RPM, while maintaining the temperature at 35°C. This produced a dispersion of dark blue silver nanoplatelets, which was then cooled to room temperature. Formula 1.23 g of the compound (a mixture of CAS 80584-88-9 and 80584-89-0) was added, and the mixture was stirred at room temperature for 1 hour.

[0407] B-2. Separation and Purification of Ag Nanoplatelets

[0408] B-2a. First Decantation

[0409] After adding 9.6 g of sodium dodecyl sulfate to the reaction mixture, about 25 g of anhydrous sodium sulfate powder was added in portions while stirring until the transmission color of the dispersion changed from blue to pink. Then, the mixture was left at room temperature for 24 hours without stirring to allow aggregated nanoplatelets to settle at the bottom of the reactor.

[0410] 890 g of supernatant was pumped from the reactor using a peristaltic pump, and 890 g of deionized water was added to the reactor. The mixture in the reactor was stirred at room temperature for 1 hour to redisperse the solidified particles.

[0411] B-2b. Second Decantation

[0412] Approximately 64 g of anhydrous sodium sulfate powder was added in portions while stirring until the transmittance of the dispersion changed from blue to yellowish-pink. The mixture was then left unstirred at room temperature for 12 hours to allow aggregated nanoplatelets to settle at the bottom of the reactor. 990 g of the supernatant was pumped from the reactor using a peristaltic pump, and 90 g of deionized water was added to the reactor. The resulting mixture was stirred at room temperature for 30 minutes to redisperse the aggregated particles.

[0413] B-2c. Ultrafiltration in water

[0414] The dispersion of the generated Ag nanoplatelets was ultrafiltered using a Millipore Amicon 8400 stirred ultrafiltration cell. The dispersion was diluted with deionized water to a weight of 400 g and ultrafiltered using a polyethersulfone (PES) membrane with a cut-off value of 300 kDa to a final volume of approximately 50 mL. This procedure was repeated a total of four times to provide a 60 g dispersion of Ag nanoplatelets dissolved in water. After completing ultrafiltration, the formula 0.17 g of the compound (a mixture of CAS 80584-88-9 and 80584-89-0) was added to the dispersion.

[0415] Ag content 28.9 wt%; yield of about 89% based on total silver content; solid content (at 250°C) 33.5 wt%; silver with a purity of 86 wt% based on solid content at 250°C.

[0416] B-2d. Ultrafiltration in isopropanol

[0417] The dispersion was further ultrafiltered in isopropanol. 60 g of silver nanoplatelet dispersion obtained after ultrafiltration in water was placed in a Millipore Amicon 8400 stirred ultrafiltration cell and diluted with isopropanol to a weight of 300 g. The dispersion was ultrafiltered to a volume of approximately 50 mL using a polyethersulfone (PES) membrane with a cut-off value of 500 kDa. This procedure was repeated a total of four times to provide 72 g of Ag nanoplatelet dispersion dissolved in isopropanol.

[0418] Ag content 24.1 wt%; solid content (at 250°C) 25.7 wt%; silver with a purity of 93.5 wt% based on solid content at 250°C.

[0419] UV-Vis-NIR spectrum 9.8*10 -5 It was recorded in water at the Ag concentration of M. λ max = 700 nm; maximum absorption coefficient ε = 10200 L / (cm*mol Ag), FWHM = 340 nm.

[0420] Average diameter of silver nanoplatelets 93±40 nm, average thickness of silver nanoplatelets 16±2.5 nm.

[0421] Preparation of B-3 dispersion D1

[0422] a) Surface deformation of Ag nanoplatelets

[0423] item B-2d 50 g (12.85 g of solid) of Ag nanoplatelet dispersion obtained as described in was placed in a 250 mL round-bottom flask under an argon atmosphere at 23°C. 2.05 g of a 5 wt% carbon disulfide solution dissolved in absolute ethanol was added and the mixture was stirred for 5 minutes, after which 2.77 g of a 5 wt% diethanolamine solution dissolved in absolute ethanol was added. The mixture was stirred at 23°C for 1 hour, after which 2.77 g of a 5 wt% diethanolamine solution dissolved in absolute ethanol was added and the mixture was stirred continuously for 30 minutes.

[0424] The UV-Vis-NIR spectrum is 9.8*10 -5 It was recorded in water at an Ag concentration of M. λ max = 704 nm.

[0425] b) Solvent conversion

[0426] step a) 15.0 g of ethyl 3-ethoxypropionate was added to the dispersion obtained from. The resulting mixture was concentrated in a rotary evaporator at a pressure of 40 mbar and a bath temperature of 40°C until no more solvent was distilled. Ethyl 3-ethoxypropionate (corresponding to a calculated total solid content of 41.2 wt%) was added to adjust the weight of the resulting dispersion to 32.1 g.

[0427] Preparation of B-4 dispersion D2

[0428] a) Surface deformation of Ag nanoplatelets

[0429] item B-2d 50 g (12.85 g of solid) of Ag nanoplatelet dispersion obtained as described in was placed in a 250 mL round-bottom flask under an argon atmosphere at 23°C. 2.05 g of a 5 wt% carbon disulfide solution dissolved in absolute ethanol was added and the mixture was stirred for 5 minutes, after which 2.77 g of a 5 wt% diethanolamine solution dissolved in absolute ethanol was added. The mixture was stirred at 23°C for 1 hour, after which 2.77 g of a 5 wt% diethanolamine solution dissolved in absolute ethanol was added and the mixture was stirred continuously for 30 minutes.

[0430] The UV-Vis-NIR spectrum is 9.8*10 -5 It was recorded in water at an Ag concentration of M. λ max = 704 nm.

[0431] b) Solvent conversion

[0432] step a)15.0 g of 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate (CAS: 2386-87-0) was added to the dispersion obtained from. The resulting mixture was concentrated in a rotary evaporator at a pressure of 40 mbar and a bath temperature of 40°C until no more solvent was distilled. The weight of the resulting dispersion was adjusted to 32.1 g by adding 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate (CAS: 2386-87-0) (corresponding to a calculated total solid content of 41.2 wt%).

[0433] C. Examples (E1-E26), Comparative Examples (C1-C8) and the manufacture of their printed security features

[0434] Description of the components of Examples (E1-E26) and Comparative Examples (C1-C8)

[0435] Table 1. ingredient

[0436]

[0437]

[0438] a) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyl dithiocarbamate in ethyl-3-ethoxypropionate (763-69-9).

[0439] b) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyl dithiocarbamate in 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate (Uvacure 1500, 2386-87-0).

[0440] C1. Manufacturing of security inks (E1-E8) according to the present invention and their dichroic security features

[0441] C1a. Manufacture of Hybrid Security Ink E1-E8

[0442] do Table 2a The ingredients provided are independently mixed and dispersed at room temperature using Dispermat CV-3 at 2000 rpm for 10 minutes to form the ink. E1-E8I obtained 50 g.

[0443] Table 1a. UV-Vis radiation-curable screen printing ink E1-E8 Composition of

[0444]

[0445]

[0446] a) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyl dithiocarbamate in ethyl-3-ethoxypropionate (763-69-9).

[0447] b) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyl dithiocarbamate in 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate (Uvacure 1500, 2386-87-0).

[0448] C1b. Manufacture of security features

[0449] UV-Vis Radiation-Curing Screen Printing Hybrid Security Ink E1-E8 It was independently applied onto a portion of a transparent polymer substrate (PET Hostaphan® RN, thickness 50 μm, supplied by Putz GmbH + Co. Folien KG) using a 160 thread / cm screen (405 mesh). The size of the printed pattern was 5 cm x 5 cm. 10 seconds after the printing step, the portion of the printed substrate was placed in an IST Metz GmbH dryer (2 lamps: iron-coated mercury lamps 200 W / cm²). 2 + Mercury lamp 200 W / cm 2 Security features were created by independently curing at room temperature by exposing to UV-Vis light at a speed of 100 m / min twice.

[0450] C1c. Results of security features (optical properties)

[0451] item C1bThe optical properties of each security feature obtained were independently evaluated upon reflection, transmission, and visual inspection using the three tests described below. The results are Table 1c It was summarized in.

[0452] Reflectance measurements were performed using a goniometer (Codec WI-10 5&5 goniometer from Phyma GmbH, Austria). The L*a*b* values ​​of the printed security features were determined at 0° relative to the normal at an illumination angle of 22.5° from the side of the printed transparent polymer substrate. The C* value (corresponding to a measure of chroma, color intensity, or color saturation) was calculated from the a* and b* values ​​according to the CIELAB (1976) color space, and the formula is as follows:

[0453]

[0454] The C* value (reflection 22.5 / 0˚) is as follows Table 1c It is displayed in.

[0455] Transmission measurements were performed using a Datacolor 650 spectrophotometer (parameters: integrating sphere, diffuse illumination (pulsed xenon D65), and 8˚ viewing angle, Analyzer SP2000 with a dual 256 diode array for a wavelength range of 360 to 700 nm, and a transmission sampling hole of size 22 nm). The C* values ​​(transmission 8˚) are as follows: Table 1c It is displayed in.

[0456] Visual evaluation was performed by visually observing each security feature upon reflection from a diffuse source (such as light entering through a window without direct sunlight when an observer faces the wall opposite the window). The following colors were observed:

[0457] - Matte appearance and brown to dark brown without metallic effect;

[0458] - Gold color with a glossy appearance and metallic effect (i.e., metallic yellow). The metallic effect appears when the saturation value C* at reflection 22.5 / 0˚ is greater than approximately 20.

[0459] In addition, a visual evaluation was performed by visually observing each security feature upon transmission. The following colors were observed:

[0460] - Faint blue: Weak blue tint (though visible);

[0461] - Blue (saturation value C* at 8˚ transmission of about 20 or more) to dark blue (saturation value C* at 8˚ transmission of 30 or more): blue coloring is intense to very intense.

[0462] Table 1c As shown in [figure], the ink according to the present invention E1-E8 The security features obtained from it showed a gold color upon reflection and a blue to dark blue color upon transmission.

[0463] Table 1c. ink E1-E8 Color characteristics of security features obtained from

[0464]

[0465] Table 1c As demonstrated by, a solvent-containing hybrid security ink according to the present invention comprising a mixture of an alicyclic epoxide and a radical-curable monomer / oligomer or a mixture of an alicyclic epoxide, a radical-curable monomer / oligomer, and a cationic-curable monomer. E1-E7 and solvent-free hybrid security ink according to the present invention E8 It provides security features with excellent visual aspects and a high saturation value C* in both reflected and transmitted light.

[0466] C2. Manufacturing of security inks (E9-E15) according to the present invention and their dichroic security features

[0467] C2a. Preparation of cationic curable security inks E9-E15

[0468] Table 2aMix and disperse the provided ingredients at room temperature using Dispermat CV-3 at 2000 rpm for 10 minutes to make the ink E9-E15 50 g of each were obtained.

[0469] Table 2a. UV-Vis radiation-curable screen printing ink E9-E15 Composition of

[0470]

[0471] a) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyl dithiocarbamate in ethyl-3-ethoxypropionate (763-69-9).

[0472] b) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyl dithiocarbamate in 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate (Uvacure 1500, 2386-87-0).

[0473] C2b. Manufacture of security features

[0474] UV-Vis radiation-curable screen printing ink E9-E15 It was independently applied onto a portion of a transparent polymer substrate (PET Hostaphan® RN, thickness 50 μm, supplied by Putz GmbH + Co. Folien KG) using a 160 thread / cm screen (405 mesh). The size of the printed pattern was 5 cm x 5 cm. 10 seconds after the printing step, the portion of the printed substrate was placed in an IST Metz GmbH dryer (2 lamps: iron-coated mercury lamps 200 W / cm²). 2 + Mercury lamp 200 W / cm 2 Security features were created by independently curing at room temperature by exposing to UV-Vis light at a speed of 100 m / min twice.

[0475] C2c. Results of security features (optical properties)

[0476] item C2b The optical characteristics of the security features obtained from the item C1c It was independently evaluated during reflection, transmission, and visual inspection using the tests described in [link].

[0477] Comparative ink according to the present invention E9-E15 The color upon reflection, color upon transmission, and C* value (reflection 22.5 / 0˚ and transmission 8˚) indicated by the security feature manufactured using Table 2c It is displayed in (below).

[0478] Table 2c. ink E9-E15 Color characteristics of security features obtained from

[0479]

[0480] Table 2c As demonstrated by, the cationic curable solvent-free security ink according to the present invention comprising an alicyclic epoxide, or an alicyclic epoxide and other cationic curable monomers E9-E12 and cationic curable solvent-containing security ink according to the present invention E13-E15 It provides security features with excellent visual aspects and a high saturation value C* in both reflected and transmitted light.

[0481] C3. A study on the effect of surfactants on optical properties exhibited by security features (comparative inks C1-C7 and inks E16-E18 according to the present invention)

[0482] To evaluate the effect of a surfactant on the optical properties exhibited by security features, a comparative ink according to the present invention C1-C7 and ink E16-E18 Manufactured.

[0483] C3a. Preparation of Inks C1-C7 and E16-E18

[0484] Table 3a Mix and disperse the provided ingredients at room temperature using Dispermat CV-3 at 2000 rpm for 10 minutes to make the ink C1-C7 and E16-E18 50 g were obtained for each.

[0485] Table 3a.UV-Vis radiation-curable screen printing ink C1-C7 and E18-E20 Composition of

[0486]

[0487] a) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyl dithiocarbamate in ethyl-3-ethoxypropionate (763-69-9).

[0488] C3b. Manufacture of security features

[0489] UV-Vis radiation-curable screen printing ink C1-C7 and E16-E18 It was independently applied onto a portion of a transparent polymer substrate (PET Hostaphan® RN, thickness 50 μm, supplied by Putz GmbH + Co. Folien KG) using a 160 thread / cm screen (405 mesh). The size of the printed pattern was 5 cm x 5 cm. 10 seconds after the printing step, the portion of the printed substrate was placed in an IST Metz GmbH dryer (2 lamps: iron-coated mercury lamps 200 W / cm²). 2 + Mercury lamp 200 W / cm 2 Security features were created by independently curing at room temperature by exposing to UV-Vis light at a speed of 100 m / min twice.

[0490] C3c. Results of security features (optical properties)

[0491] item C3b The optical characteristics of security features in the item C1c It was independently evaluated during reflection, transmission, and visual inspection using the tests described in [link].

[0492] ink C1-C7 and E16-E18 The color upon reflection, color upon transmission, and C* value (reflection 22.5 / 0˚ and transmission 8˚) indicated by the security feature manufactured using the following Table 3c It is displayed in.

[0493] Table 3c. ink C1-C7 and E16-E18 Color characteristics of security features obtained from

[0494]

[0495] Table 3c As shown in [figure], functionalized with a hydroxyl group (Fluorolink E10H: ink E16 ), functionalized with (meth)acrylate groups (Fluorolink MD700: ink E17 ), functionalized with silane groups (Fluorolink S10: ink E18 The security feature obtained from the ink according to the present invention, comprising a perfluoropolyether surfactant, exhibits a gold color upon reflection and a deep blue color upon transmission. In comparison, a perfluoropolyether surfactant without the functional group (Fluorolink F10: comparative ink) C1 ) or BYK 330 (comparison ink C2 ), BYK 371(comparison ink C3 ), TEGO RAD 2300(comparison ink C4 ), TEGO RAD 2700(comparison ink C5 ), Dynasylan F8815 (comparison ink) C6 ) and Dynasylan F8261 (comparison ink) C7 Security features obtained from inks containing surfactants without perfluoropolyether chains, such as ), exhibit a faint blue to blue color upon transmission but a dark brown to brown color with low saturation upon reflection. The dark brown to brown color with low saturation upon reflection does not attract attention and is therefore not suitable for dichroic security features to secure valuable documents.

[0496] C4. A study on the effect of the amount of perfluoropolyether surfactant on the optical properties exhibited by the security features (comparative ink C8 and inks E19-E23 according to the present invention)

[0497] To evaluate the effect of the amount of perfluoropolyether surfactant described herein on the optical properties exhibited by the security features, the ink according to the present invention C8 and E19-E23 It was manufactured as described below.

[0498] C4a. Preparation of Inks C8 and E19-E23

[0499] Table 4a Mix and disperse the provided ingredients at room temperature using Dispermat CV-3 at 2000 rpm for 10 minutes to make the ink C8 and E19-E23 50 g were obtained for each.

[0500] Table 4a. UV-Vis radiation-curable screen printing ink C8 and E19-E23 Composition of

[0501]

[0502] a) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyl dithiocarbamate in ethyl-3-ethoxypropionate (763-69-9).

[0503] C4b. Manufacture of security features

[0504] UV-Vis radiation-curable screen printing ink C8 and E19-E23 It was independently applied onto a portion of a transparent polymer substrate (PET Hostaphan® RN, thickness 50 μm, supplied by Putz GmbH + Co. Folien KG) using a 160 thread / cm screen (405 mesh). The size of the printed pattern was 5 cm x 5 cm. 10 seconds after the printing step, the portion of the printed substrate was placed in an IST Metz GmbH dryer (2 lamps: iron-coated mercury lamps 200 W / cm²). 2 + Mercury lamp 200 W / cm 2 Security features were created by independently curing at room temperature by exposing to UV-Vis light at a speed of 100 m / min twice.

[0505] C4c. Results of security features (optical properties)

[0506] item C4b The optical characteristics of the security features obtained from the item C1c It was independently evaluated during reflection, transmission, and visual inspection using the tests described in [link].

[0507] ink C8 and E19-E23 The color upon reflection, color upon transmission, and C* value (reflection 22.5 / 0˚ and transmission 8˚) indicated by the security feature manufactured using the following Table 4c It is displayed in.

[0508] Table 4c. ink C8 and E19-E23 Color characteristics of security features obtained from

[0509]

[0510] Table 4c As shown in [the example], using about 0.05 weight% to about 5 weight% of a perfluoropolyether surfactant as described in this specification (e.g., ink E19-E23 Ensures that the secure features of Fluorolink E10H used in exhibit a highly saturated metallic yellow upon reflection and a deep blue upon transmission (ink E19-E23 ). In comparison, ink that does not contain surfactants C8 The security feature obtained from the experiment performed by [the company] exhibits a dark brown to brown color with low saturation values ​​upon reflection. This color does not attract the attention of the general public and cannot be used as a security feature to secure valuable documents.

[0511] C5. A study on the effect of the type of polyvinyl chloride copolymer on the optical properties exhibited by the security features (inks E1 and E24-E26 according to the present invention)

[0512] To evaluate the effect of the type of polyvinyl chloride copolymer on the optical properties exhibited by the security features, the ink according to the present invention E1 and E24-E26 It was manufactured as described below.

[0513] C5a. Preparation of Inks E1 and E24-E26

[0514] Table 5a Mix and disperse the provided ingredients at room temperature using Dispermat CV-3 at 2000 rpm for 10 minutes to make the ink E1 and E24-E26 50 g were obtained for each.

[0515] Table 5a. UV-Vis radiation-curable screen printing ink E1 and E24-E26 Composition of

[0516]

[0517] a) Polyvinyl chloride / polyvinyl acetate (85.6% / 14.4%) (9003-22-9), K value 35±1, molecular mass 3-4·10 4 Dalton (Wacker, size-exclusion chromatography)

[0518] b) Polyvinyl chloride / polyvinyl acetate (63% / 37%) (9003-22-9), K value 50±1, molecular mass 6-8·10 4 Dalton

[0519] c) Polyvinyl chloride / (acrylic acid / 1,2-propanediol copolymer) (57495-45-1) (84% / 16%), K value 39±1, molecular mass 4-5·10 4 Dalton

[0520] d) Polyvinyl chloride / (acrylic acid / 1,2-propanediol / butendodiic acid dibutyl ester copolymer) (114653-42-8) (75% / 25%), K value 48±1, molecular mass 6-8·10 4 Dalton

[0521] e) 41.2 wt% Ag nanoplatelets stabilized with diethanolammonium dihydroxyethyldithiocarbamate in ethyl-3-ethoxypropionate (763-69-9)

[0522] C5b. Manufacture of security features

[0523] UV-Vis radiation-curable screen printing ink E1 and E24-E26It was independently applied onto a portion of a transparent polymer substrate (PET Hostaphan® RN, thickness 50 μm, supplied by Putz GmbH + Co. Folien KG) using a 160 thread / cm screen (405 mesh). The size of the printed pattern was 5 cm x 5 cm. 10 seconds after the printing step, the portion of the printed substrate was placed in an IST Metz GmbH dryer (2 lamps: iron-coated mercury lamps 200 W / cm²). 2 + Mercury lamp 200 W / cm 2 Security features were created by independently curing at room temperature by exposing to UV-Vis light at a speed of 100 m / min twice.

[0524] C5c. Results of security features (optical properties)

[0525] item C5b The optical characteristics of the security features obtained from the item C1c It was independently evaluated during reflection, transmission, and visual inspection using the tests described in [link].

[0526] ink E1 and E24-E26 The color upon reflection, color upon transmission, and C* value (reflection 22.5 / 0˚ and transmission 8˚) indicated by the security feature manufactured using the following Table 5c It is displayed in.

[0527] Table 5c. ink E1 and E24-E26 Color characteristics of security features obtained from

[0528]

[0529] Table 5c As demonstrated by the color characteristics of the security features shown in the invention, the security ink claimed herein, comprising a polyvinyl chloride copolymer containing at least about 60 weight%, preferably at least about 63 weight%, of vinyl chloride, provides security features that exhibit blue to dark blue upon reflection and metallic yellow upon reflection.

[0530] C6. A study on the stability of UV-Vis radiation-curable security ink E2 according to the present invention through accelerated aging experiments

[0531] To evaluate the safety of the ink according to the present invention over time, 10 g of ink E2 ( Table 1a As described in) the cup (SpeedMixer provided by Hauschild & Co. KG) TM The newly manufactured ink was placed in a 60 mL white polypropylene cup, completely sealed, and stored in a laboratory oven (Kendro Laboratory Products, T6060) at 60°C for 5 months. E2 was used as the comparison standard. For each month, the ink stored in the oven E2 After cooling the sample at room temperature for 6 hours, it was applied onto a portion of a transparent polymer substrate (PET Hostaphan® RN, thickness 50 μm, supplied by Putz GmbH + Co. Folien KG) using a 160 thread / cm screen (405 mesh). The size of the printed pattern was 5 cm x 5 cm. Ten seconds after the printing step, the portion of the printed substrate was placed in an IST Metz GmbH dryer (2 lamps: iron-coated mercury lamps 200 W / cm²). 2 + Mercury lamp 200 W / cm 2 Security features were generated by curing at room temperature through two exposures to UV-Vis light at a speed of 100 m / min. The optical properties of the security features obtained each month are item C1c It was independently evaluated at reflection and visually using the test described in. Table 6 It summarizes the color upon reflection, the color upon transmission, and the C* value (reflection 22.5 / 0˚) represented by the security feature.

[0532] Table 6. Color characteristics of security features

[0533]

[0534] a)The security feature is the newly manufactured ink according to the present invention. E2 It was manufactured as.

[0535] Table 6 As demonstrated by the optical properties of the security features shown in, the ink according to the present invention E2 It remains stable for extended periods at high temperatures, which is an indicator of excellent shelf stability at room temperature.

Claims

Claim 1 As a UV-Vis radiation-curable security ink for manufacturing security features that appear blue when viewed under transmitted light and metallic yellow when viewed under incident light, a) As silver nanoplatelets of about 7.5 wt% to about 20 wt%, having an average diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, an average thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and an average aspect ratio greater than 2.0, wherein the average diameter is determined by transmission electron microscopy and the average thickness is determined by transmission electron microscopy, and the following general formula ( I Silver nanoplatelets containing a surface stabilizer of ); ( I In the above formula, residue R A is a C2-C4 alkyl group substituted with a hydroxyl group; and a residue R B is selected from C2-C4 alkyl groups substituted with hydroxyl groups and C1-C4 alkyl groups; Cat + is a general formula + NH2R C R D It is an ammonium cation of, and residue R C is a C2-C4 alkyl group substituted with a hydroxyl group; residue R D is selected from C2-C4 alkyl groups and C1-C4 alkyl groups substituted with hydroxyl groups; b) About 45 weight% to about 80 weight% of a cycloaliphatic epoxide or a mixture of a cycloaliphatic epoxide and one or more UV-Vis radiation-curable compounds; c) One or more cationic photoinitiators; d) A perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of hydroxyl, acrylate, methacrylate, and trialkoxysilyl; e) About 3 weight% to about 12 weight% of a polyvinyl chloride copolymer containing at least 60 weight% of vinyl chloride; and optionally, f) UV-Vis radiation-curable security ink comprising up to about 25 weight% of an organic solvent, wherein the weight% is based on the total weight of the UV-Vis radiation-curable security ink. Claim 2 A UV-Vis radiation-curable security ink according to claim 1, wherein the security ink is selected from screen printing security ink, rotogravure security ink, and flexography security ink. Claim 3 A UV-Vis radiation-curable security ink according to claim 1 or 2, wherein the average diameter of the silver nanoplatelets is within the range of 70 to 120 nm with a standard deviation of less than 50%, the average thickness of the silver nanoplatelets is within the range of 8 to 25 nm with a standard deviation of less than 30%, and the average aspect ratio of the silver nanoplatelets is greater than 2.

5. Claim 4 In paragraph 1 or 2, the general formula ( I The surface stabilizer of ) a) UV-Vis radiation-curable security ink containing silver nanoplatelets in an amount of about 0.5% to about 5% by weight. Claim 5 In paragraph 1 or 2, the residue R A and R B UV-Vis radiation-curable security ink in which C2-C4 alkyl groups are independently substituted with hydroxyl groups. Claim 6 In paragraph 1 or 2, the silver nanoplatelet is of the following general formula ( II UV-Vis radiation-curable security ink containing an additional surface stabilizer of: ( II In the above formula, Silver represents a bond to silver; R 1 H, C1-C 18 It is alkyl, phenyl, C1-C8alkylphenyl, or CH2COOH; R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are independently H, C1-C8 alkyl or phenyl; Y is O or NR 8 And; R 8 is H or C1-C8 alkyl; k1 is an integer within the range of 1 to 500; k2 and k3 are independently 0 or integers within the range of 1 to 250; k4 is 0 or 1 and; k5 is an integer within the range of 1 to 5. Claim 7 In paragraph 1 or 2, the silver nanoplatelet is of the following general formula ( III UV-Vis radiation-curable security ink containing an additional surface stabilizer of: ( III In the above formula, R 17a , R 17b and R 17c are independently H or methyl; R 18a and R 18b is H or methyl; R 19a is a saturated or unsaturated, straight-chain or branched-chain alkyl having 1 to 22 carbon atoms; R 19b is R c -[O-CH2-CH2-] c -O- and; R 19c Is , , , , , , -C(=O)-NH-(CH2) y NR 15 R 16 or -C(=O)-NH-(CH2) y N + HR 15 R 16 An - And; An - is an anion of a monovalent organic or inorganic acid; y is an integer from 2 to 10; R 15 is a saturated or unsaturated, straight-chain or branched-chain alkyl having 1 to 22 carbon atoms; R 16 It is a saturated or unsaturated, straight-chain or branched-chain alkyl with 1 to 22 carbon atoms; R c is a saturated or unsaturated, straight-chain or branched-chain alkyl having 1 to 22 carbon atoms, or an alkylaryl or dialkylaryl having up to 24 carbon atoms, and c is 1 to 150; y1 , y2 and y3 are independent integers from 1 to 200. Claim 8 In paragraph 1 or 2, the silver nanoplatelet is of the following general formula ( IV UV-Vis radiation-curable security ink containing an additional surface stabilizer of: ( IV In the above formula, R 9 is a hydrogen atom or formula -CHR 11 -N(R 12 )(R 13 It is the basis of ); R 10 is a hydrogen atom, a halogen atom, a C1-C8 alkoxy group, or a C1-C8 alkyl group; R 11 is H or C1-C8 alkyl; R 12 and R 13 are independently C1-C8 alkyl, C1-C8 alkyl groups substituted with hydroxyl groups, or the formula -[(CH2CH2)-O] n1 It is a -CH2CH2-OH group, and n1 It is 1 to 5. Claim 9 A UV-Vis radiation-curable security ink according to claim 1 or 2, wherein one or more UV-Vis radiation-curable compounds comprise one or more cationic-curable monomers selected from the group consisting of vinyl ether, prophenyle ether, cyclic ether other than alicyclic epoxide, lactone, cyclic thioether, vinyl thioether, prophenyle thioether, hydroxyl-containing compounds, and mixtures thereof. Claim 10 In claim 1 or 2, one or more UV-Vis radiation-curable compounds comprise one or more radical-curable monomers and / or oligomers, and UV-Vis radiation-curable security ink g) UV-Vis radiation-curable security ink further comprising one or more free radical photoinitiators. Claim 11 A UV-Vis radiation-curable security ink according to claim 1 or 2, comprising about 0.025 weight% to about 5 weight% of a perfluoropolyether surfactant, wherein the weight% is based on the total weight of the UV-Vis radiation-curable security ink. Claim 12 UV-Vis radiation-curable security ink according to claim 1 or 2, which is solvent-free. Claim 13 A method for manufacturing a security feature for securing a value document that appears blue when viewed under transmitted light and metallic yellow when viewed under incident light, A) A step of providing an ink layer by printing a UV-Vis radiation-curable security ink according to claim 1 or 2 onto a transparent or partially transparent area of ​​the substrate of a value document; and B) step A) A method comprising the step of UV-Vis curing an ink layer obtained from to form security features. Claim 14 In paragraph 13, the method in which the document of value is selected from banknotes, certificates, tickets, checks, vouchers, financial stamps, contracts, and identification documents. Claim 15 In paragraph 13, the method in which the value document is selected from a passport, identification card, visa, driver's license, bank card, credit card, transaction card, access document and card, admission ticket, public transport ticket, academic diploma and academic title.

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