EP3763541A1

EP3763541A1 - Data carrier and a method of production of the data carrier

Info

Publication number: EP3763541A1
Application number: EP20184544.3A
Authority: EP
Inventors: Slawomir Ziólkowski
Original assignee: Polska Wytwornia Papierow Wartosciowych SA
Current assignee: Polska Wytwornia Papierow Wartosciowych SA
Priority date: 2019-07-10
Filing date: 2020-07-07
Publication date: 2021-01-13
Anticipated expiration: 2040-07-07
Also published as: PL430543A1; PL3763541T3; EP3763541B1

Abstract

The object of the invention is a data carrier comprising a layer at least partially coated with a layer of material with optically variable properties, the layer of material with optically variable properties being transparent, wherein
at least part of the area coated with the material with optically variable properties (401) is transparent,
wherein the carrier further comprises an at least partially transparent laser-markable layer (104) wherein markings capable of being made with a laser can be applied, such that the markings after being applied will be visible from both sides of the carrier,
wherein the laser-markable layer (104) is located so that the laser-made marking (501) after application thereof will partially obscure the visibility of the coating with optically variable properties (401) from one side (601) of the carrier, and from the other side (602) of the carrier it will provide a contrasting background for the coating with optically variable properties (401), therefore providing the marking (501), seen from the laser-unmarked side (602) of the carrier, with optically variable properties.

The invention further relates to a method of production of the multi-layered data carrier according to the invention.

Description

Technical field

The present invention relates to a data carrier, comprising a layer coated at least in part with a layer of material with optically variable properties and to a method of production of such a multi-layer data carrier.

Background art

Data carriers, such as documents, in form of a laminate of several layers are known, the carriers possibly comprising various types of security features. This applies in particular to carriers that must be protected against forgery, such as passports, visa documents, identification documents, driving licences, vehicle registration cards, bank cards and documents, certificates, banknotes, etc. Data carriers may comprise various types of markings, such as general markings (e.g. document name, etc.) and/or individual markings (e.g. personal data, photograph, document number, etc.).
In security features, materials with optically variable properties are often used, which give different optical impressions (related to e.g. changes in colour or its shades) depending on the angle at which the material is perceived. Such materials include, among others, iridescent or interference dyes and pigments or liquid crystal paints. A known technical problem with the use of a liquid crystal layer with optically variable properties is the fact that to make the optically variable properties visible it is required to observe this layer on a contrasting, for example dark or black, background. For this reason, the solutions described in the prior art include documents observed from one side wherein a substrate providing a contrasting background is placed underneath the optically variable layer or an external contrasting background is required for observation.
Technologies simultaneously using laser marking require an additional layer susceptible of laser marking that is sensitive to laser radiation because it contains at least one compound that reacts to laser radiation (e.g. carbon black) or is susceptible to being engraved with laser beams. Laser marking is usually carried out after the individual layers have been joined by lamination, with the laser beams passing through the individual layers of the carrier reaching the layer susceptible to laser marking. If a layer with optically variable properties is used simultaneously, it is necessary to use such a layer with optically variable properties that is permeable to light, in particular permeable to the laser wavelengths used (as described e.g. in PL196736). The intensity of laser radiation should also be selected so that the layer with optically variable properties is not altered under its influence. In practice, many materials with optically variable properties absorb a portion of laser radiation and many interference pigments react to some extent to laser exposure, which may affect the optically variable effect obtained and/or the visibility of markings underneath the optically variable layer (e.g. markings made by laser) ( WO2015189404 ).
EP1281538 describes a multi-layered document comprising a layer with optically variable properties on a semi-transparent substrate and a metallic layer lying underneath those, fragments of which are removed to form a marking. This marking gives a different impression depending on which side of the document it is observed, and the properties of the optically variable layer can be observed against the background of the unremoved metallic layer.
EP1778501 describes a document containing an element comprising a liquid crystal material which, in transmitted light, provides a first optical impression, while in light falling against a predetermined and easily accessible background, which is created by a highly absorbent dark surface, provides a second optical impression which is significantly different from the first optical impression, namely, firstly, the authenticity feature in light falling on a highly absorbent dark surface shows an optically variable effect, and secondly, in light falling on a highly absorbent dark surface, the appearance or information content of the patterns, signs or codings of the authenticity feature is significantly altered, or the patterns, signs or codings disappear completely.
In turn, document WO2015189404 describes a technology in which a security comprises a laser-marked layer, with some markings being observable through an optically variable layer and some not, giving a different optical effect. Laser marking is carried out through the optically variable layer and is observed on one side of the document, and different impressions are caused by the possibility of observation of a portion of the markings through the optically variable layer, as well as by the use of additional markings made by means of printing with a paint or pigment which are susceptible to laser irradiation.
EP2114690 describes a document comprising at least one transparent layer. The document has a determined section allowing to look through, with the transparent area containing markings, for example, made by laser marking, placed between two types of material with different properties when exposed to UV. Due to these two types of material, the markings observed in ultraviolet rays on one side provide a different impression than when observed from the other side.
On the other hand, international application WO2014187825 discloses a data carrier with laser-crafted markings, observed against a semi-reflective layer, so that those markings are visible in reflected light on one side of the document but not on the other, but can be observed on both sides of the document in transmitted light.
The present inventors have developed a way to produce a security feature utilising a layer with optically variable properties and a technique of laser marking, as well as a method of production of a multi-layer, secured data carrier such as a document, for example an ID card or a personalised passport page that contains this security feature.
The present invention therefore relates to a data carrier comprising a layer at least partially coated with a layer of material with optically variable properties, the layer of material with optically variable properties being transparent,
wherein at least part of the area coated with the material with optically variable properties is transparent,
wherein the carrier further comprises an at least partially transparent laser-markable layer wherein markings capable of being made with a laser can be applied, such that the markings after being applied will be visible from both sides of the carrier,
wherein the laser-markable layer is located so that the laser-made marking after application thereof will partially obscure the visibility of the coating with optically variable properties from one side of the carrier, and from the other side of the carrier will provide a contrasting background for the coating with optically variable properties, therefore providing the marking, seen from the laser-unmarked side of the carrier, with optically variable properties.
In a preferred embodiment of the data carrier according to the invention, between the coating with optically variable properties and the laser-markable layer is at least one transparent layer that is non-laser-markable, wherein preferably the coating with optically variable properties is located between transparent layers that are non-laser-markable.
Preferably, the carrier includes a laser-markable layer, with laser-applied markings visible from both sides of the carrier, with the laser-markable side of the carrier showing a marking, preferably black or dark, contrasting with the surroundings, which at least partially obscures the visibility of the coating with optically variable properties, wherein the same marking observed on the opposite, laser-unmarked side of the carrier, i.e. the side with the visible coating with optically variable properties, creates a contrasting, preferably black or dark, background for the coating with optically variable properties, providing the marking seen on the laser-unmarked side of the carrier with optically variable properties.
In a preferred embodiment of the data carrier according to the invention, the markings capable of being made with a laser are laser-engraved markings.
In a preferred embodiment of the data carrier according to the invention, it contains an inner layer which is at least semi-transparent or opaque, preferably bright, e.g. white, wherein the inner layer is covered on both sides by transparent outer layers, and only in a portion of the area of the carrier there is an opening in the inner layer, wherein the area of the opening is at least partly covered by a coating with optically variable properties from one, laser-unmarked, side of the carrier and with laser markings from the other, laser-markable, side of the carrier.
Preferably, the opening is filled with transparent filling material.
Preferably, a coating with optically variable properties is located in the area of the transparent filling, wherein between the coating with optically variable properties and the laser-markable layer is an at least one transparent layer that is non-laser-markable, wherein preferably the coating with optically variable properties is located between transparent layers that are not laser-markable.
Preferably, the height of the filling differs by at most +/- 10% from the height of the opening.
The invention further relates to a method of production of a multi-layer data carrier, the method comprising the following steps:

a) applying a transparent material with optically variable properties to at least a portion of the area of one of the layers of a multi-layer data carrier structure, wherein at least a portion of the area coated with the material with optically variable properties is transparent;
b) combining, preferably in a process of lamination, layers of the multi-layer data carrier structure, including the layer coated at least partially with the material with optically variable properties obtained in step a), and a laser-markable layer, wherein the laser-markable layer is placed such that the markings can be applied with a laser from one side of the carrier so that the laser beams can reach the laser-markable layer without passing through the material with optically variable properties.

In a preferred embodiment of the method according to the invention, in step b), between the layer coated at least partially with the material with optically variable properties obtained in step a) and the laser-markable layer, a transparent layer which is non-laser-markable is arranged.
In a preferred embodiment of the method according to the invention, the method additionally includes, after step b), step c) of applying markings in the laser-markable layer with a laser, wherein during marking, the laser beam does not pass through the material with optically variable properties, and at least a portion of the markings thus applied is visible from both sides of the carrier, wherein from the laser-markable side of the carrier which is subjected to laser marking, the marking at least partially obscures the visibility of the layer with optically variable properties, and the same marking observed from the opposite, laser-unmarked side of the carrier, that is, the side with the visible layer with optically variable properties, creates a contrasting, preferably black or dark, background for the layer with optically variable properties, which ensures optically variable properties for the marking seen from the laser-unmarked side of the carrier.
In a preferred embodiment of the method according to the invention, the application of markings in step c) is carried out by means of laser engraving.
In a preferred embodiment of the method according to the invention, in step b), the individual layers of the data carrier are connected by placing the layer with optically variable properties between transparent layers that are non-laser-markable layers.
Preferably, the method according to the invention further includes, prior to step a), a step of making an opening in one of the layers of the multi-layer structure of the data carrier when at least one of the layers of the multi-layer structure of the data carrier is opaque, wherein in step a), the material with optically variable properties is applied to at least a portion of the area of the opening prepared as above, and wherein optionally in step c), markings are applied by laser to at least a portion of the area of the opening prepared as above.
Preferably, the opening is filled with transparent filling material.
Preferably, the coating with optically variable properties is placed in the area of the transparent filling between transparent layers that are non-laser-markable.
Preferably, the filling height differs by at most +/- 10% from the depth of the opening.
The subject matter according to the invention involves applying a coating of material with optically variable properties 401 on one of the layers of a multi-layer structure of a data carrier (for example, a document), wherein the carrier further includes a laser-markable layer 104 (Fig. 1). The application of the coating with optically variable properties can be achieved, for example, by printing a transparent liquid crystal ink with optically variable properties or by applying a transparent film with such properties to one of the layers of the multi-layer document structure or by another method known to one skilled in the art. The coating made of material with optically variable properties can therefore be applied, for example, using well-known printing techniques such as screen printing, flexographic printing, pad printing. The optically variable properties of a material, such as an ink or a film, are revealed when the material is placed on a contrasting, preferably black, background. The individual layers of the multi-layer structure are combined in a way that is known in the art, e.g. using an adhesive, cold lamination, hot lamination, etc. For example, a hot lamination process can be used that requires the right temperature, pressure and time. Then, using a laser with an appropriate wavelength, for example within the range of 1060-1070 nm, markings 501 can be applied, preferably in black or dark (e.g. grey scale) colour, for example as graphic elements, numbers and/or personal data such as e.g. a photo. The markings can be applied with lasers as known in the field, for example with an Nd:YAG 1064 nm laser. The laser-markable layer 104 can be made from any suitable material known in the art. Exemplary materials include polycarbonate (PC), polyethylene terephthalate (PET/PETG), polypropylene (PP), poly(vinyl chloride) PVC, a PC and PETG composite (PEC). Markings are applied in the laser-markable layer 104 so that the laser beam does not pass through the printed or applied coating with optically variable properties 401.
Thus, the laser-markable layer 104 is placed from one side of the data carrier, above the coating with optically variable properties 401, and due to this the laser-markable layer 104 can absorb all the energy of the laser, hence the beam thereof not changingg the properties of the coating with optically variable properties 401, but only causing blackening in the area of the laser-markable layer 104, for example, susceptible of laser engraving. The markings 501 applied by laser may take a form of fixed graphic elements e.g. images, marks, logos or may contain personalized data such as, for example, a photo, first name, surname, expiry date of the document or date of birth. Laser markings can be markings in positive or negative and can include elements such as fine guilloche lines or microtexts.
This method of application of laser markings, from the laser-markable side 601 of the carrier, with the laser-markable layer 104, results in an image contrasting with the surroundings, preferably in black or shades of grey, which at least partially obscures the visibility of the layer with optically variable properties 401. The same image, observable from the opposite, laser-unmarked side 602 of the carrier, i.e. the side with visible coating with optically variable properties 401, creates a contrasting, preferably dark or black background for the coating with optically variable properties 401, due to this the image visible on this side of the carrier acquiring optically variable properties. In addition, a dark image is visible when observing in transmitted light.
Thus, in the data carrier according to the invention, two sides can be distinguished:

a laser-markable side 601, closer to the laser-markable layer 104 and
a laser-unmarked side 602, closer to the coating with optically variable properties 401.

The laser markings 501 can therefore be made so that the laser beam does not pass through the printed or applied coating with optically variable properties 401 and does not change the properties of the coating. The resulting data carrier according to the invention can therefore be provided with the markings 501 visible from both sides of the carrier as well as in transmitted light.
Particularly preferably, the coating with optically variable properties 401 is located so that a transparent, non-laser-markable layer is placed between the coating with optically variable properties 401 and the laser-markable layer 104. Preferably, the coating with optically variable properties 401 is placed between transparent layers that are not susceptible to laser marking (e.g. engraving). Such a transparent layer, which is not laser-markable, may comprise various materials known to one skilled in the art, such as polycarbonate (PC), polyethylene (PE), polypropylene (PP), poly(vinyl chloride) (PVC), or various resins such as phenolic, phenol-formaldehyde resins, etc. wherein the materials do not include an addition of laser-sensitive pigments such as carbon black (non-engravable films). Person skilled in the art will be able to choose convenient materials from the commonly known in the art.
The individual layers forming the data carrier according to the invention may comprise materials well known to the person skilled in the art, such as, but not limited to, plastic or synthetic materials, thermoplastic or thermosetting materials and plastics, for example: polycarbonate (PC), polyethylene (PE), polypropylene (PP), poly(vinyl chloride) (PVC), or various resins, for example: phenolic, phenol-formaldehyde resins, etc.
Materials with optically variable properties are well known in the art. Such materials include, among others, opalescent or interference dyes and pigments or liquid crystal paints, for example, liquid crystal paints known in the art, e.g. SICPA OASIS® (manufactured by SICPA), COLORCRYPT® LC (manufactured by MERCK), or dyes and pigments known in the art, e.g. Iriodin, Pyrisma, Colorstream, Miraval - MERCK, Mearlin, Lumina, Firemist, Magnapearl - BASF. For example, but not exclusively, such materials are described in US 5,084,351 ; US 5,171,363 ; US 5,653,792 ; US 5,279,657 ; US 5,571,624 ; US 5,569,535 ; US 5,383,995 ; US 5,059,245 ; US 4,838,648 .
In embodiments of the invention, the entire data carrier is transparent. In alternative embodiments, the data carrier further contains an inner layer (core) 101 which is at least translucent or opaque (preferably bright, e.g. white). The carrier further comprises transparent outer layers 102. In this embodiment, only in a certain portion of the carrier area, an opening 201 is made in the inner layer 101 (Fig. 2). The opening 201 can be made using a plotter, a laser or any other method known in the art. In a preferred embodiment, the opening 201 is furthermore filled with transparent filling material 301. The filling can be made from a material similar to the other layers of the data carrier, e.g. it is preferable when the body of the data carrier and the filling are made of the same material, e.g. polycarbonate.
Preferably, the filling 301 is matched in shape and thickness to the opening 201. Preferably the individual dimensions of the filling are smaller than the corresponding dimensions of the opening 201, which enables easy and precise placement of the filling in the opening. Preferably, the height of the filling 301 differs by at most +/- 10% from the depth of the opening 201.
The coating of material with optically variable properties 401 is applied (e.g., by printing or any other method known in the art) at least in the area of the opening 201, for example, over the lower or upper surface of one of the transparent outer layers 102 or over the lower or upper surface of the transparent outer filling 301 filling the opening 201 or over the lower or upper surface of one of the outer layers of the transparent filling 301 (Fig. 3). Particularly preferably, the coating with optically variable properties 401 is located in the area of the transparent filling 301 between transparent layers that are not susceptible to laser marking (e.g. engraving). The material with optically variable properties 401 may therefore be applied as a continuous layer or coating, or may cover only a portion of the surface area of the data carrier, but at least the portion comprising the opening 201. The carrier side closer to the coating with optically variable properties 401 is the laser-unmarked side 602 of the carrier.
The data carrier of the embodiment further comprises, from the side opposite to the laser-unmarked side 602 of the carrier, at least above the opening 201, at least one layer that may be subject to laser marking 104, for example, laser-engravable, allowing laser marking and the application of contrasting, preferably dark or black markings, which may form the background for the coating with optically variable properties 401. The laser-markable layer 104 is located on the laser-markable side 601 of the data carrier, above the coating with optically variable properties 401, as a result of which it can absorb all the energy of the laser, its beam then not changing the properties of the optically variable coating, but only causing blackening in the area of the layer that may be susceptible to laser marking 104, for example, susceptible to laser engraving.
Therefore, the method developed by the present inventors allows to obtain a data carrier having a security feature, providing a completely different optical impression when observed from two sides of the data carrier containing the feature. Moreover, the subject matter of the invention provides the possibility of using the markings with optically variable properties in a transparent element (without the need for a contrast layer, e.g. dark substrate). Production with the method according to the invention is relatively simple and does not require the laser parameters to be adjusted to the characteristics of the material with optically variable properties, as the laser marking is made in such a way that the laser beam does not pass through the material with optically variable properties.
The structure of the data carrier is not limited to the layout of layers as shown in the embodiments. Person skilled in the art will appreciate that as long as the possibility is maintained of making laser markings in such a way that the laser beams does not pass through the material with optically variable properties and the laser markings made can be observed from both sides of the carrier (from the side of the application of laser markings and from the side of the layer of the material with optically variable properties), the remaining layers possibly present may have a different order or layout.

Description of figures

Fig. 1 shows a data carrier according to the invention comprising a layer of material with optically variable properties and a layer that can be laser-marked.
Fig. 2 presents a data carrier, comprising an opening in a semi-transparent or opaque inner layer.
Fig. 3 shows a data carrier according to a preferred embodiment of the invention as shown in Fig. 2 comprising a layer of material with optically variable properties and a layer that can be laser-marked.

EXAMPLES

Fig. 1 is a schematic view of a cross-section of a data carrier containing a security feature with optically variable properties according to an embodiment of the invention. The carrier has a layered structure, wherein individual layers are transparent. The carrier comprises a layer coated with a coating of material with optically variable properties, wherein the layer of material with optically variable properties 401 is transparent. The carrier further comprises a laser-markable layer 104, above the coating with optically variable properties 401, due to which the laser-markable layer 104 can absorb all the energy of the laser, the laser beam therefore not changing the properties of the coating with optically variable properties 401, but only causing a blackening in the area of the laser-markable layer 104, for example, susceptible to laser engraving. The markings 501 applied by laser, after application thereof, partially obscure the visibility of the coating with optically variable properties from one side 601 of the carrier, and from the other side 602 of the carrier provide a contrasting background for the coating with optically variable properties 401, which provides the marking 501 being seen from the laser-unmarked side 602 of the carrier with optically variable properties.
In other words, this method of application of markings makes it possible to observe, under incident light, a contrasting, preferably dark or black marking, from the laser-markable side 601 of the carrier while providing a different impression of an optically variable image depending on the angle of observation from the laser-unmarked side 602 of the carrier, from the coating with optically variable properties 401. In addition, a dark image is visible when observing in transmitted light.
Fig. 2 is a schematic view of across-section of another embodiment of a data carrier containing a security feature with optically variable properties according to an embodiment of the invention. The carrier has a layered structure and contains one inner layer 101 (core), which is opaque (white) and on both sides having a transparent outer layer 102, which completely transmits light. The inner layer 101 in the area of the security feature contains an opening 201 made with a cutting plotter equipped with a knife. The inner layer 101, in the area of the opening, contains a filling 301, compensating for differences in thickness, consisting of transparent layers forming a window in the opaque card body. The filling 301 is adjusted to the shape and thickness of the opening 201.
Fig. 3 is a schematic view of a cross-section of a data carrier at the location of the optically variable security feature according to an embodiment of the invention. The coating with optically variable properties 401 is produced by printing. The coating 401 is applied at the place of the transparent filling 301 between transparent layers that are not susceptible to laser engraving. The data carrier includes at least one laser markable layer 104, in the example being susceptible to laser engraving, allowing laser marking and the application of contrasting dark markings that provide a background for the coating with optically variable properties. The laser-markable layer 104 is placed from the laser-markable side 601 of the data carrier, above the coating with optically variable properties 401, due to which it can absorb all the energy of the laser, the laser beam therefore not changing the properties of the optically variable coating, but only causing a blackening in the area of the layer that may be laser-marked 104, for example, susceptible to laser engraving. The laser-applied markings 501 may take form of fixed graphic elements e.g. images, marks, logos or contain personalised data such as, for example, a photo, first name, surname, expiry date of the document or date of birth.
The laser applied markings are applied from the laser-markable side 601 of the carrier with a visible layer susceptible to laser marking. This method of marking application makes it possible to observe, under incident light, a contrasting, preferably dark or black marking, from the laser-markable side 601 of the carrier while providing a different impression of an optically variable image depending on the angle of observation from the laser-unmarked side 602 of the carrier, from the coating with optically variable properties 401. In addition, a dark image is visible when observing in transmitted light.

Claims

A data carrier comprising a layer at least partially coated with a layer of material with optically variable properties, the layer of material with optically variable properties being transparent, characterized in that
at least part of the area coated with the material with optically variable properties (401) is transparent,
wherein the carrier further comprises an at least partially transparent laser-markable layer (104) wherein markings capable of being made with a laser can be applied, such that the markings after being applied will be visible from both sides of the carrier,
wherein the laser-markable layer (104) is located so that the laser-made marking (501) after application thereof will partially obscure the visibility of the coating with optically variable properties (401) from one side (601) of the carrier, and from the other side (602) of the carrier it will provide a contrasting background for the coating with optically variable properties (401), therefore providing the marking (501), seen from the laser-unmarked side (602) of the carrier, with optically variable properties.
The data carrier according to claim 1, characterized in that between the coating with optically variable properties (401) and the laser-markable layer (104) is at least one transparent layer that is non-laser-markable, wherein preferably the coating with optically variable properties (401) is located between transparent layers that are non-laser-markable.
The data carrier according to claim 1 or 2, characterized in that it includes a laser-markable layer (104), with laser-applied markings (501), the markings (501) being visible from both sides of the carrier,
with the laser-markable side (601) of the carrier showing a marking (501), preferably black or dark, contrasting with the surroundings, which at least partially obscures the visibility of the coating with optically variable properties (401), wherein the same marking (501) observed from the opposite, laser-unmarked side (602) of the carrier, i.e. the side with the visible coating with optically variable properties (401), creates a contrasting, preferably black or dark, background for the coating with optically variable properties (401), providing the marking (501) seen from the laser-unmarked side (602) of the carrier with optically variable properties.
The data carrier according to any of claims 1-3, characterized in that the laser-applied markings (501) are laser engraved markings.
The data carrier according to any of claims 1-4, characterized in that it contains an inner layer (101) which is at least semi-transparent or opaque, preferably bright, e.g. white, wherein the inner layer (101) is covered on both sides by transparent outer layers (102), and only in a portion of the area of the carrier there is an opening (201) in the inner layer (101), wherein the area of the opening is at least partly covered by a coating with optically variable properties (401) from one, laser-unmarked, side (602) of the carrier and with laser markings (501) from the other, laser-markable (601), side of the carrier.
The data carrier according to claim 5, characterized in that the opening (201) is filled with a transparent filling material (301).
wherein preferably a coating with optically variable properties (401) is located in the area of the transparent filling (301), wherein between the coating with optically variable properties (401) and the laser-markable layer (104) is an at least one transparent layer that is non-laser-markable, wherein preferably the coating with optically variable properties (401) is located between transparent layers that are not laser-markable.
The data carrier according to claim 6, characterized in that the height of the filling (301) differs by at most +/- 10% from the depth of the opening (201).
A method of production of a multi-layer data carrier, characterized in that the method comprises the following steps:
a) applying a transparent material with optically variable properties to at least a portion of the area of one of the layers of a multi-layer data carrier structure, wherein at least a portion of the area coated with the material with optically variable properties is transparent;

b) combining, preferably in a process of lamination, layers of the multi-layer data carrier structure, including the layer coated at least partially with the material with optically variable properties obtained in step a), and a laser-markable layer,
wherein the laser-markable layer is placed such that the markings can be applied with a laser from one side of the carrier so that the laser beams can reach the laser-markable layer without passing through the material with optically variable properties.
The method according to claim 8, characterized in that in step b), between the layer coated at least partially with the material with optically variable properties obtained in step a) and the laser-markable layer, a transparent layer which is non-laser-markable is arranged.
The method according to claim 8 or 9, characterized in that, after step b), it further comprises a step:
c) applying markings in the laser-markable layer with a laser, wherein during marking, the laser beam does not pass through the material with optically variable properties, and at least a portion of the markings thus applied is visible from both sides of the carrier, wherein from the laser-markable side of the carrier which is subjected to laser marking, the marking at least partially obscures the visibility of the layer with optically variable properties, and the same marking observed from the opposite, laser-unmarked side of the carrier, that is, the side with the visible layer with optically variable properties, creates a contrasting, preferably black or dark, background for the layer with optically variable properties, which ensures optically variable properties for the marking seen from the laser-unmarked side of the carrier.
The method according to any of claims 8-10, characterized in that the application of markings in step c) is carried out by means of laser engraving.
The method according to any of claims 9-12, characterized in that in step b), the individual layers of the data carrier are connected by placing the layer with optically variable properties between transparent layers that are non-laser-markable layers.
The method according to any of claims 8-12, characterized in that it further includes, prior to step a), a step of making an opening in one of the layers of the multi-layer structure of the data carrier, when at least one of the layers of the multi-layer structure of the data carrier is opaque, wherein in step a), the material with optically variable properties is applied to at least a portion of the area of the opening prepared as above, and wherein optionally in step c), markings are applied by laser to at least a portion of the area of the opening prepared as above.
The method according to claim 13, characterized in that the opening is filled with a transparent filling material.
wherein preferably the coating with optically variable properties is placed in the area of the transparent filling between transparent layers that are non-laser-markable.
The method according to claim 14, characterized in that the height of the filling differs by at most +/- 10% from the depth of the opening.