DE102006008247A1 - Laser-marked safety features for protecting valuable objects, has laser-marked marking substance with core-covering-particles, and one of the material of the core and covering absorbs the radiation of the marking laser - Google Patents

Abstract

The features has a laser-marked marking substance with core-covering-particles (20,30). One of the material of the core (22,32) and covering (24) absorbs the radiation of the marking laser and the other materials of core and covering does not absorb the radiation of the marking laser. Independent claims are also included for the following: (1) a method for manufacturing of a laser-marked safety features (2) a safety paper for the manufacturing of protective cover or value document (3) a data carrier e.g. branded articles, value documents.

Description

The The invention relates to a laser-markable security element for Protection of valuables, a method for producing such a security element and a security paper and a data carrier with such a security element.

Disk, like Value or identity documents, or other valuables, such as Branded articles are often provided with security elements for protection provided a review of the Authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction. Such security elements can for example in the form of a security thread embedded in a banknote, a tear thread for product packaging, an applied safety strip or a self-supporting Transfer element may be formed, such as a patch or a label, which is applied to a value document after its production.

For individual marking of the security elements laser inscribers are used, for example, based on CO ₂ lasers, Nd: YAG lasers or UV lasers. Depending on the wavelength of the marking laser used, however, there are restrictions with regard to the usable laser-markable feature substances. For example, currently used luminescent materials and many IR absorbers absorbing in the range below 1000 nm or above 1300 nm are markable with Nd: YAG lasers.

outgoing One of the objects of the invention is a laser-markable one Specify security element of the type mentioned, the Disadvantages of the prior art avoids. In particular, a safety element is intended for the safety element size A range of laser-markable feature substances and substance complexes for UV and near-infrared lasers for producing visually and / or machine-detectable UV or IR marks are provided.

These Task is by the laser markable security element with the Characteristics of the independent Claim solved. A method for producing such a security element, a security paper and a data carrier with such a security element are given in the independent claims. further developments The invention are the subject of the dependent claims.

According to the invention contains a generic laser markable Security element a laser-markable feature substance with core-shell particles, wherein one the materials of core and shell absorbs the radiation of one marking laser and the other the materials of core and shell does not absorb the radiation of the marking laser.

In a preferred embodiment, the feature substance of the security element can be marked by laser radiation in the near infrared, in particular at wavelengths of about 1.06 μm. For marking, it is then advantageously possible to use Nd: YAG lasers or related types of lasers, such as Nd: glass or Nd: YVO ₄ lasers. In a further, likewise preferred embodiment, the feature substance can be marked by laser radiation in the ultraviolet spectral range.

at a first variant of the invention forms the non-laser absorbing Material the core of the core-shell particles. The markability of the core-shell particles is added this variant produced by a laser-absorbing Hüllenmate rial. alternative The non-laser absorbing material forms the shell of the Core-shell particles. In this variant of the invention, the laser-absorbent core material imparts the core-shell particle the laser markability.

The non-laser absorbing material of the core-shell particles comprises with advantage one or more luminescent substances. Suitably, the core-shell particles are of an organic or inorganic protective cover surrounded to prevent material separation during laser marking.

Of the In addition to the core-shell particles, feature substance may additionally have one or more not coated with laser absorbing material Contain luminescent substance. The coated and uncoated Luminescent substances can each according to the desired Effect at the same wavelength or be excitable at different wavelengths.

Also Advantageously, the non-laser absorbing material may be one or more have multiple infrared absorber. For marking with an Nd: YAG laser The infrared absorbers are advantageous for absorption in the wavelength range between 800 nm and 1000 nm and / or in the range of 1300 nm to 1600 nm designed. Also in this variant, the core-shell particles of the feature substance are useful from surrounded by an organic or inorganic protective cover, to material separation to prevent the laser marking.

To Another variant of the invention is the non-laser absorbing Material a colored pigment, such as Yellow 13 or Red 48. By coating with a laserablatierbaren shell This results in a colorful, laser-markable feature substance.

In all designs come as laser-absorbent materials ever at the choice of the marking laser, luminescent substances, IR absorbers, UV absorbers or colored pigments into consideration.

The Invention contains also a method for producing a laser-markable security element, in which a laser-markable feature substance of core-shell particles is generated by either a laser absorbing material with a non-laser absorbing material is encapsulated, or a non-laser absorbing material with a laser absorbing Material is encapsulated.

One Security paper for the production of security or value documents, such as banknotes, checks, ID cards, certificates or the like, is preferably with a Laser-markable security element of the type described above fitted. The security paper can in particular be a carrier substrate made of paper or plastic. The invention further contains a data carrier, in particular a branded article, a value document or the like, which with equipped a security element of the type described above is.

Further embodiments as well as advantages of the invention are described below with reference to FIGS explained. For better clarity, the figures refer to a scale and proportionally true representation omitted.

It demonstrate:

1 a schematic representation of a banknote with a security element according to the invention,

2 in (a) to (c) embodiments of core-shell particles according to embodiments of the invention,

3 schematically in (a) a surface printed with a feature substance according to the invention, and in (b) the surface after laser marking with a Nd: YAG laser, and

4 a combination of printed and lasered markings.

The invention will now be explained using the example of a banknote. 1 shows a schematic representation of a banknote 10 that with a security element according to the invention 12 Is provided.

For laser marking with a Nd: YAG laser contains the security element 12 at least one Nd: YAG laser-ablatable luminescent feature substance. Depending on the desired application, the luminescence of the feature substance can be visually visible or lie outside the visible spectral range. The term luminescence encompasses both fluorescence and phosphorescence.

In a first, in 2 (a) illustrated feature of the invention contains the feature substance core-shell particles 20 whose core 22 is formed by a luminescent substance with the desired luminescence behavior. As the luminescent 22 Even if Nd: YAG laser ablatable, it will be coated with a Nd: YAG laser ablatable sheath 24 capsuled. For this purpose, for example, a dissolved infrared absorber for 1064 nm is grown on the luminescent substance and dried. Alternatively, the IR absorber can also be applied to the luminescent substance by means of plasma coating.

The reverse sequence of luminescent substance and IR absorber is possible, as in 2 B) shown. In the core-shell particle shown there 30 is a laser ablatable core 32 , For example, from an IR absorber for 1064 nm, with a self-laserablatierbaren luminescent 34 coated with desired luminescence properties.

The core-shell particles of luminescent substance and IR absorber may additionally contain one or more protective sheaths 26 have, as in 2 (c) shown to prevent material separation during laser marking. The protective sheaths may be inorganic, for example of SiO _x , or organic.

In order to ensure the markability with Nd: YAG lasers, the dyes known as ADS990MC or ADS1065A of the American Dye Source can be used as the laser-ablatable substances, for example. The dye ADS990MC with the composition C ₃₂ H ₃₀ N ₂ S ₄ Ni has an absorption maximum in the near infrared at 990 nm, the dye ADS1065A having the composition C ₆₂ H ₉₂ N ₆ F ₁₂ Sb ₂ has an absorption maximum in methanol at 1060 nm.

Suitable luminescent substances for the various applications are known to the person skilled in the art. For example only, luminescent LUMILUX ^® CD 135 and CD 140 may be mentioned by Honeywell. LUMILUX ^® CD 135 with the composition ZnS: Mn fluoresces orange after excitation with UV radiation, LUMILUX ^® CD 140 with the composition ZnS: Cu exhibits a yellowish green phosphorescence after excitation with UV radiation. Both luminescent substances are themselves not Nd: YAG laser ablatable, but form in the inventive combination with a laserablatierbaren shell or a laser-ablatable core an Nd: YAG-markable feature substance.

3 shows in (a) a surface printed with a feature substance according to the invention 42 for the laser marking with a Nd: YAG laser at 1064 nm. The feature substance in the exemplary embodiment contains a luminescent at 1500 nm luminescent substance itself at 1064 nm not absorbed, but encapsulated in the manner described above with an IR absorber for 1064 nm is. In laser marking with the Nd: YAG marking laser, the luminescent feature substance is ablated in regions in the form of a desired marking, as indicated by the reference numeral 44 in 3 (b) indicated. The inscribed marking can then be read later in the luminescence light with a suitable sensor for 1500 nm.

The invention also allows for the combination of printed and laser engraved markings as in 4 shown. 4 (a) shows a printed label 52 in which the printing ink contains a feature substance according to the invention. The printed label can therefore be characterized by exposure to the infrared radiation of an Nd: YAG marker laser with further labeling 54 be provided. While the first mark 52 usually visually identifiable, may be the further labeling 54 be visible visually or even by machine with a suitable sensor. It is particularly appropriate to the printed label 52 to use as static code that is the same for a variety of security elements while the lasered label 54 represents a in individual coding, which identifies the respective security element or a valuable object provided with it individually.

It is understood that the feature substances according to the invention also more complex can be constructed as previously described for illustration. For example, the Feature substance a mixture of two or more, coated with IR absorber Contain luminescent substances that are excited at the same wavelength become. The non-ablated areas show luminescence a corresponding mixed color, the ablated areas remain without luminescence.

In other embodiments are only certain of the plurality of luminescent substances encapsulated with IR absorber while other luminescent substances of the feature substance remain uncoated and therefore not ablated during laser marking. For example the feature substance can be a yellow and a red luminescent substance both excited at the same wavelength and from where only the yellow luminescent material is encapsulated with IR absorber. Laser marking thus only the yellow luminescent substance eroded, leaving the imprint in the ablated areas red luminescent, in the non ablated areas, however, in the Mixed color orange.

It can also short and long wavelength stimulable luminescent substances combined be either with only the short-wave or only the long-wave excitable Luminescent substance is encapsulated with IR absorber. Depending on the excitation wavelength is the inscribed identification then recognizable in the luminescent light or not.

Also a combination of fluorescent and phosphorescent luminescent substances comes in question, where either only the fluorescent or only the phosphorezierende Material is encapsulated with IR absorber. In the former case disappears the marking in the luminescence light shortly after the excitation, im second case, it appears after the decay of the first dominant Fluorescent radiation.

Instead of The luminescent substance may also be used as a non-ablatable material a second IR absorber can be used which is not at the wavelength of the Marking laser absorbed. For example, the first IR absorber, as described above, for the label is designed with a Nd: YAG laser at 1064 nm, while the second IR absorber in the spectral range between 800 nm and 1000 nm absorbed.

With a Nd: YAG marker laser can then be in the printed area a label, such as a barcode label, is inscribed, the more common IR sensors for the near infrared can be read. The second IR absorber of course also for Absorption at other wavelengths, for example, at about 1500 nm.

As described above, the two IR absorbers can additionally have one or more protective sheaths in order to prevent material separation during laser inscription. The protective sheaths may be inorganic, for example of SiO _x , or organic.

A further design options consists of using single or multiple colored pigments, such as for example, Yellow 13 or Red 48, as non-ablatable material. The Colored pigments are coated or coated with a laser dye, to form a laser-ablatable feature substance. These too Core-shell particles can be provided with an organic or inorganic protective cover.

Let a UV laser be used as the marking laser are set, is used as a laser absorbing material tuned to the wavelength of the laser UV absorber. The UV absorber may also be a luminescent substance. Non-laser-absorbable materials include various luminescent substances, IR absorbers or colored pigments.

Claims (16)

Laser-markable security element for protection of valuables, characterized in that the security element is a laser markable Contains feature substance with core-shell particles, wherein one of the materials of core and shell the radiation of a marking laser absorbed and the other of the materials of the core and shell the Radiation of the marking laser is not absorbed. Laser-markable security element according to claim 1, characterized in that the feature substance by laser radiation in the near infrared, in particular at wavelengths of about 1.06 microns, markable is. Laser-markable security element according to claim 1, characterized in that the feature substance by laser radiation can be marked in the ultraviolet spectral range. Laser-markable security element according to at least one of the claims 1 to 3, characterized in that the non-laser absorbing material the core of the core-shell particles forms. Laser-markable security element according to at least one of the claims 1 to 3, characterized in that the non-laser absorbing material the case the core-shell particle forms. Laser-markable security element according to at least one of the claims 1 to 5, characterized in that the non-laser absorbing material comprises one or more luminescent substances. Laser-markable security element according to claim 6, characterized in that the core-shell particles of the feature substance surrounded by an organic or inorganic protective cover, to material separation to prevent the laser marking. Laser-markable security element according to claim 6 or 7, characterized in that the feature substance additionally at least a luminescent material not coated with laser-absorbing material contains. Laser-markable security element according to at least one of the claims 1 to 5, characterized in that the non-laser absorbing material having one or more infrared absorbers. Laser-markable security element according to claim 9, characterized in that the infrared absorber on absorption in the wavelength range between 800 nm and 1000 nm and / or in the range of 1300 nm to 1600 nm designed are. Laser-markable security element according to claim 9 or 10, characterized in that the core-shell particles of the feature substance surrounded by an organic or inorganic protective sheath are to prevent material separation during laser marking. Laser-markable security element according to at least one of the claims 1 to 5, characterized in that the non-laser absorbing material is a colored pigment. Laser-markable security element according to at least one of the claims 1 to 12, characterized in that the laser-absorbing material Ma a luminescent substance, an IR absorber, a UV absorber or a Is colored pigment. Method for producing a laser-markable Security elements to secure valuables, in a laser-markable feature substance of core-shell particles is produced by either a laser absorbing material with a not encapsulated in a laser-absorbing material, or not laser absorbing material with a laser absorbing material is encapsulated. Security paper for the production of security or value documents, such as banknotes, checks, identity cards, certificates or the like, with a security element according to at least one of the claims 1 to 14 is equipped. disk, in particular branded articles, documents of value or the like, with a security element according to at least one of claims 1 to 14 is equipped.