METHOD AND DEVICE FOR ADDING A SECURITY ELEMENT AND A BLUND OF AN IDENTIFICATION, VALUE OR SECURITY DOCUMENT

Abstract

Method for joining a security element (206) and a blank (202) of an identification, value or security document (200), comprising the steps: - Providing the blank (202) and the security element (206), - Applying a radiation-curable adhesive to a surface of the blank (202) and / or to a surface of the safety element (206), wherein the radiation-curable adhesive comprises a plurality of different photoinitiators activatable by actinic radiation from the ultraviolet spectrum, - Applying the security element (206) to the blank (202) such that the adhesive is located between the blank (202) and the security element (206), and - Curing of the adhesive by means of a drying device (110) comprising at least one UV LED (112) which emits light in at least two different, discrete ultraviolet wavelength ranges adapted to the respective photoinitiators, wherein the UV LED (112) emits light in a first wavelength range from 350 nanometers to 380 nanometers and light in a second wavelength range from 385 nanometers to 415 nanometers.

Description

[0001] The invention relates to a method for joining a security element and a blank of an identification, valuable, or security document by bonding. The invention also relates to a device for carrying out this method.

[0002] Identification, valuables, or security documents serve to verify the identity of a person or object or a claim, for example, to payment of money or the release of a product or provision of a service. To this end, it must be ensured that the document cannot be imitated, forged, or falsified, or only with considerable effort. Therefore, the document is often provided with security elements or features that are extremely difficult or even practically impossible to imitate.For this purpose, it is known, for example, to apply a security element to a blank of an identification, valuables, or security document. This element can be provided with an imprint using special colors, for example, luminescent or optically variable colors, optical elements such as tilt images, kinegrams, lens or prism arrays, as well as guilloche patterns, mottled fibers, security threads, and other decorations. Security elements can also include holograms, preferably formed as volume reflection holograms.

[0003] To ensure a secure bond between the security element and the blank of the ID, valuables, or security document, it is known to cure the adhesive in a drying device, thereby forming a bond between the blank and the security element that cannot be removed without destruction. For this purpose, a radiation-curable adhesive is used, for example, which cures when irradiated with light from a visible or non-visible wavelength spectrum. To achieve the desired curing of the adhesive, lamps such as mercury vapor lamps, which emit light with a very broad spectrum, are used. The use of conventional UV lamps has proven to be sensible and practical, as the UV drying of the adhesive with conventional lamps is very rapid, thus enabling high throughput in the production of ID, valuables, or security documents.However, since the adhesive usually only needs to cure under light from a narrow wavelength band, it can happen that broadband light sources radiate wavelengths into the material of the blank or the security element that lead to damage to the materials.

[0004] DE 10 2018 112 652 A1 presents a method for producing a laminated body in which a radiation-curable adhesive is applied to a laminating film before the laminated film is bonded to a transfer film using the adhesive. This involves a laminating film to which the radiation-curable adhesive layer is selectively applied using a printing device before a decorative layer is applied.

[0005] DE 10 2015 112 909 B3 describes a very similar process to that contained in DE 10 2018 112 652 A1. This also describes a process for producing a multilayer film using a UV-curable adhesive, whereby the adhesive is applied using a printing process. A UV LED is used for curing.

[0006] DE 10 2008 021 944 A1 describes a method and device for applying strip-shaped continuous films to a substrate web. The substrate web is bonded to the continuous film, with a cascade of UV lamps present to cure the adhesive between the two webs.

[0007] It is therefore the object of the present invention to provide a method and a device for joining a security element and a blank of an identification, value or security document, which overcome the above-mentioned disadvantage.

[0008] This object is achieved by a method having the features of claim 1 and by a device having the features of claim 8. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0009] The method for joining a security element and a blank of an identification, value or security document comprises in particular the following steps: - Providing the blank and the security element, - applying a radiation-curable adhesive to a surface of the blank and / or to a surface of the security element, wherein the adhesive comprises at least one photoinitiator activatable by actinic radiation from the ultraviolet spectrum, - applying the security element to the blank in such a way that the adhesive is located between the blank and the security element, and - Curing the adhesive by means of a drying device comprising at least one UV LED which emits light in an ultraviolet wavelength range adapted to the at least one photoinitiator of the adhesive.

[0010] This offers the advantage that a light-emitting diode (UV LED) emitting in the ultraviolet spectrum, or an array of several such UV LEDs, is used to cure the adhesive. The present invention is therefore based on and incorporates the finding that, while UV drying with a conventional UV lamp could result in a shorter curing time than with UV drying using the UV LED according to the invention, this longer curing time is deliberately accepted because drying the adhesive using the UV LED results in a significantly lower penetration of wavelengths not involved in drying the adhesive into the material of the security element.

[0011] Unlike conventional UV mercury vapor lamps, the ambient oxygen is not converted into ozone due to the strong irradiation, which would have to be constantly extracted. In addition, UV LEDs have a shorter warm-up phase than conventional UV mercury vapor lamps, meaning the device is ready for use more quickly. UV LEDs are also subject to significantly smaller intensity fluctuations than mercury vapor lamps. Another key advantage is the narrowband radiation characteristic of UV LEDs, which means that a smaller proportion of radiation from a wavelength range not required for curing reaches the loose composite of the blank, adhesive layer, and security element.

[0012] According to the invention, the radiation-curable adhesive comprises a plurality of different photoinitiators that are activated during the curing step by actinic radiation from the UV LED, which in turn emit light in at least two different ultraviolet wavelength ranges matched to the respective photoinitiators. By using an adhesive with different types of photoinitiators, improved curing can be achieved than would be the case with just one photoinitiator, i.e., only one wavelength range used for curing. In this way, the UV LED is designed as a type of "UV combination LED" that uses the available installation space more efficiently due to its smaller size. This allows the exposure section of the drying device to be designed more compactly, while the effective exposure time is increased.Improved hardening also results in a security element that is more difficult to remove from the blank of the identification, valuables or security document, thus increasing its security against forgery.

[0013] If photoinitiators are used that can be activated in a wavelength range between 200 nm and 600 nm, the invention provides that the UV LED emits light in a first wavelength range from 350 nm to 380 nm and light in a second wavelength range from 385 nm to 415 nm. Preferably, the UV LED emits light in a first wavelength range from 360 nm to 370 nm and light in a second wavelength range from 395 nm to 410 nm. These two wavelength ranges have proven advantageous when using a radiation-curable adhesive formed with corresponding photoinitiators. The curing efficiency is further increased by the UV LED emitting light at 365 nm and light at 400 nm. It is understood that the specified wavelengths represent the peak wavelengths and may be subject to certain fluctuations.

[0014] In order to provide a process-reliable exposure or drying section, it has proven advantageous if the drying device comprises a cascade of a first lamp head and at least one further lamp head, that the lamp heads each comprise at least one UV LED, and that the adhesive present between the blank and the security element is first partially dried with the UV LED of the first lamp head and then cured with the UV LED of the at least one further lamp head. In this way, the loose composite can be continuously transported, since the cascade causes the adhesive to cure successively. By using such a cascade, the exposure time can be increased, which leads to improved resistance of the end product to various media. This configuration also makes it possible to increase the machine speed and thus increase production throughput.

[0015] It has proven advantageous if the method is implemented as a continuous process. In this way, it is possible for the blank to be transported by means of a transport device to an adhesive application device, for an adhesive layer to be applied to the surface of the blank by means of the adhesive application device, for the blank provided with the adhesive layer to be transported by means of the transport device to an application device, for the security element to be applied to the blank provided with the adhesive layer by means of the application device, whereby the adhesive is located between the blank and the security element, for the blank provided with the adhesive layer and the security element to be transported to the drying device, and for the adhesive to be partially dried or cured by irradiation with the light from the UV LED of the drying device.

[0016] For improved implementation of a continuous process, it has proven advantageous if the transport device comprises a circulating, in particular motor-driven, conveyor belt which is driven in a clocked or continuous manner.

[0017] The blank of the ID, valuables, or security document is preferably in a card format. Examples of suitable formats include ID1, ID2, ID3, or another format. The blank itself is generally formed as a laminate made up of multiple document layers that are precisely bonded together under heat and increased pressure. These products should meet standardized requirements, such as ISO 10373, ISO / IEC 7810, and ISO 14443. The individual layers are preferably made of a carrier material suitable for lamination, preferably made of polycarbonate. The blank is a component or forms the precursor of an ID, valuables, or security document. It is intended for further processing, such as subsequent printing, embossing, coating, or the like.It is not necessary that the application of the security element already results in the finished, completed or final identification, valuables or security document; however, the latter would still be possible.

[0018] A possible security element to be applied could be, for example, a section of a hologram film exposed with a volume reflection hologram. This can be provided, for example, on a carrier foil, from which it can be manually or automatically removed and then applied to the blank provided with the adhesive layer under pressure.

[0019] The advantages, advantageous configurations, and effects explained in connection with the method according to the invention apply equally to the device according to the invention. This includes, in particular: - A transport device having a circulating conveyor belt, - an adhesive application device configured to apply an adhesive layer of a radiation-curable adhesive to a surface of the blank, wherein the adhesive comprises at least one photoinitiator activatable by actinic radiation from the ultraviolet spectrum, - an application device which is designed to apply the security element to the blank provided with the adhesive layer in such a way that the adhesive is located between the blank and the security element, and - a drying device having at least one UV LED, which is configured to partially dry or cure the adhesive by irradiation with the light of the UV LED, wherein the UV LED is configured to emit light in an ultraviolet wavelength range adapted to the at least one photoinitiator of the adhesive.

[0020] This device enables increased production throughput with reduced cycle times, and the end products manufactured with this device exhibit greater resistance to a wide range of media. In addition, the use of UV LEDs prevents environmentally harmful ozone formation, while targeted irradiation with the narrowband LED lamps significantly reduces material damage caused by UV radiation. By using UV LEDs, which emit light in at least two different ultraviolet wavelength ranges tailored to the respective photoinitiators, the various photoinitiators in the adhesive can be specifically stimulated, reducing energy loss in the adhesive, for example, due to chemical side reactions. UV LEDs enable greater process stability, which can reduce scrap.

[0021] With regard to the design of the method, the sequence of the aforementioned process steps is expedient, but not mandatory. The raw materials do not necessarily have to be provided simultaneously, as the security element is only brought into contact with the blank after the adhesive has been applied. Another exemplary design option provides for the adhesive to first be partially dried using at least one UV LED to specifically adjust its viscosity before the security element is applied to the blank. Only then does the adhesive fully cure.

[0022] The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figure, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also considered to be encompassed and disclosed by the invention that are not explicitly shown or explained in the figure, but which emerge and can be produced through separate feature combinations from the explained embodiments.

[0023] Further advantages, features, and details of the invention will become apparent from the claims, the following description of preferred embodiments, and the drawings. Herein: Fig. 1 a schematic representation of a device for joining by gluing a security element to a blank of an identification, value or security document, which is designed to carry out the method according to the invention.

[0024] In Fig.1 shows a device 100 for joining a security element 206 and a blank 202 of an identification, valuable, or security document 200 by gluing. The blank 202 is provided on the input side (left) and picked up by a circulating conveyor belt 104 of a transport device 102. The device 100 also comprises an adhesive application device 106 configured to apply an adhesive layer 204 of a radiation-curable adhesive to a surface of the blank 202. Additionally, an application device 108 is provided, configured to apply the security element 206 to the blank 202 provided with the adhesive layer 204. The device 100 also comprises a drying device 110, in whose dryer housing, in the present case, a cascade 116 of individual lamp heads 114 is present.Each of the lamp heads 114 comprises a surface emitter formed with an array of a plurality of UV LEDs 112. The UV LEDs are formed in this case as combined UV LEDs 112 (UV combination LEDs) that emit light in at least two, but in this case exactly two different discrete wavelength ranges of the ultraviolet. Due to the use of the UV surface emitters shown here, a greater packing density of the lamp heads 114 within the drying device 110 or its housing is possible than is the case with conventional UV dryers. In this case, six of the lamp heads 114 are present in the cascade 116, although a different number of lamp heads 114 or UV surface emitters is possible.

[0025] The adhesive used is radiation-curable and, in this case, comprises at least two different photoinitiators that can be activated by actinic radiation from the ultraviolet spectrum. The photoinitiators and the wavelengths emitted by the UV LEDs 112 are matched to one another and result in more efficient curing of the radiation-curable adhesive. The UV LEDs are configured to emit light in a first wavelength range from 350 nm to 380 nm and light in a second wavelength range from 385 nm to 415 nm. Preferably, the UV LEDs are configured to emit light in a wavelength range from 360 nm to 370 nm and in the second wavelength range from 395 nm to 405 nm, with the peak wavelengths being at 365 nm and 400 nm, respectively.By using this narrow-band UV LED 112, targeted irradiation in the ultraviolet spectrum is possible, so that less energy is introduced into the materials, which could lead to undesirable chemical side reactions.

[0026] The operation of the device 100 shown is discussed below using a card-shaped blank 202 of an identification, valuables, or security document 200, to which a security element 206 of a portion of a hologram film exposed with a volume reflection hologram is to be applied. First, the blank 202 is provided, which is transported by means of the conveyor belt 104 of the conveyor device 102 to the adhesive application device 106. There, the radiation-curable adhesive is applied to the surface of the blank 202, wherein the blank 202 provided with the adhesive layer 204 is immediately transported by the conveyor device 102 to the application device 108. The application device 108 is provided with the security element 206 formed as a hologram, which is applied by the application device 108 to the blank 202 provided with the adhesive layer 204.The security element 206 is placed on the blank 202 such that the adhesive is located between the blank 202 and the security element 206. The transport device 102 then transports the blank 202, provided with the adhesive layer 204 and the security element 206, to the drying device 110, which has corresponding openings through which the conveyor belt 104 is guided. During the continuous, i.e., ongoing transport of the loose composite of the blank 202, the adhesive layer 204, and the security element 206, the adhesive is successively cured by irradiation with the UV surface radiators and is present on the output side (right) either as a finished identification, value, or security document 200 or as an intermediate product that can then be subjected to further processing steps.

[0027] As a result, the present invention provides an improvement in the product quality and durability of finished identification, value or security documents 200, wherein the machine performance of the device 100 is increased by the use of the UV LEDs 112 for curing end-product-relevant materials. LIST OF REFERENCE SYMBOLS 100 device 102 Transport device 104 Conveyor belt 106 Adhesive application device 108 Application setup 110 Drying device 112 UV LEDs / UV combo LEDs 114 Lamp head 116 Cascade 200 identification, valuables or security documents 202 blank 204 Adhesive layer 206 Security element

Claims

[1] Method for joining a security element (206) and a blank (202) of an identification, value or security document (200), comprising the steps: - Providing the blank (202) and the security element (206), - applying a radiation-curable adhesive to a surface of the blank (202) and / or to a surface of the security element (206), wherein the radiation-curable adhesive comprises a plurality of different photoinitiators that can be activated by actinic radiation from the ultraviolet spectrum, - applying the security element (206) to the blank (202) such that the adhesive is located between the blank (202) and the security element (206), and - Curing the adhesive by means of a drying device (110) comprising at least one UV LED (112) which emits light in at least two different, discrete ultraviolet wavelength ranges adapted to the respective photoinitiators, wherein the UV LED (112) emits light in a first wavelength range from 350 nanometers to 380 nanometers and light in a second wavelength range from 385 nanometers to 415 nanometers. [2] Method according to claim 1, characterized by that the UV LED (112) emits light at 365 nanometers and light at 400 nanometers. [3] Method according to claim 1 or 2, characterized bythat the drying device (110) comprises a cascade (116) of a first lamp head (114) and at least one further lamp head (114), that the lamp heads (114) each comprise at least one of the UV LEDs (112), and that the adhesive present between the blank (202) and the security element (206) is first partially dried with the UV LED (112) of the first lamp head (114) and then cured with the UV LED (112) of the at least one further lamp head (114). [4] Method according to one of claims 1 to 3, characterized by , that the blank (202) is transported by means of a transport device (102) to an adhesive application device (106), that an adhesive layer (204) is applied to the surface of the blank (202) by means of the adhesive application device (106), that the blank (202) provided with the adhesive layer (204) is transported by means of the transport device (102) to an application device (108), that the security element (206) is applied to the blank (202) provided with the adhesive layer (204) by means of the application device (108), whereby the adhesive is located between the blank (202) and the security element (206), that the blank (202) provided with the adhesive layer (204) and the security element (206) is transported to the drying device (110), and that the adhesive is partially dried or cured by irradiation with the light of the UV LED (112) of the drying device (110). [5] Method according to claim 4, characterized by that the transport device (102) comprises a circulating conveyor belt (104) which is driven in a clocked or continuous manner. [6] Method according to one of claims 1 to 5, characterized by that the blank (202) of the identification, value or security document (200) is in a card format. [7] Method according to one of claims 1 to 6, characterized by that the security element (206) is a section of a hologram film exposed with a volume reflection hologram. [8] Device (100) for joining a security element (206) and a blank (202) of an identification, value or security document (200), namely for carrying out the method according to one of claims 1 to 7, comprising: - a transport device (102) having a circulating conveyor belt (104), - an adhesive application device (106) configured to apply an adhesive layer (204) of a radiation-curable adhesive to a surface of the blank (202), wherein the radiation-curable adhesive comprises a plurality of different photoinitiators activatable by actinic radiation from the ultraviolet spectrum, - an application device (108) which is designed to apply the security element (206) to the blank (202) provided with the adhesive layer (204) in such a way that the adhesive is located between the blank (202) and the security element (206), and - a drying device (110) having at least one UV LED (112) which is configured to partially dry or cure the adhesive by irradiation with the light of the UV LED (112), wherein the UV LED (112) is configured to emit light in at least two different, discrete ultraviolet wavelength ranges adapted to the respective photoinitiators, wherein the UV LED (112) emits light in a first wavelength range from 350 nanometers to 380 nanometers and light in a second wavelength range from 385 nanometers to 415 nanometers.

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