CA2761755A1 - Ink-receiving layer having a recess - Google Patents
Ink-receiving layer having a recess Download PDFInfo
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- CA2761755A1 CA2761755A1 CA2761755A CA2761755A CA2761755A1 CA 2761755 A1 CA2761755 A1 CA 2761755A1 CA 2761755 A CA2761755 A CA 2761755A CA 2761755 A CA2761755 A CA 2761755A CA 2761755 A1 CA2761755 A1 CA 2761755A1
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H19/00—Coated paper; Coating material
- D21H19/66—Coatings characterised by a special visual effect, e.g. patterned, textured
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M5/00—Duplicating or marking methods; Sheet materials for use therein
- B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
- B41M3/14—Security printing
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- Credit Cards Or The Like (AREA)
- Printing Methods (AREA)
Abstract
The invention relates to a security paper (7) for producing valuable documents, comprising a substrate (8) having an optically variable security element (2), which can be detected when at least a first side of the substrate is observed, and an ink-receiving layer (6), which is arranged at least on the first side of the substrate, wherein the ink-receiving layer has a first layer thickness in a first substrate area lying outside the area of the optically variable security element and a recess or a reduced layer thickness compared to the first layer thickness in a second substrate area (3) in which the optically variable security element is arranged.
Description
f 7 Ink-receiving layer having a recess The invention relates to a security paper for producing valuable documents, having an optically variable security element and an ink-receiving layer having a recess, a method for producing such a security paper and an apparatus for implementing the production method, and also a valuable document produced from the security paper.
Valuable documents in the sense of the present invention are, for example, banknotes, shares, loan documents, certificates, coupons, checks, lottery tickets, high-value entry tickets, passports, identity papers, credit cards and other flat articles of value.
Such articles of value can, however, also be packaging for possibly high-value products. The term security paper in the sense of the present invention comprises precursor stages of such valuable documents which, for example, are not suitable to be circulated. The security paper can be present in quasi endless form and processed further at a later time.
Such valuable documents are often provided with security elements as a safeguard, which permit the authenticity of the valuable documents to be checked and at the same time serve as a safeguard against forbidden reproduction. In order to increase security against forgery and to make imitation more difficult, such valuable documents comprising security elements are frequently covered with a further printed image.
The optically variable security element can already be part of the security paper used for the production.
The security element used is, for example, optically variable elements, whereby, in the sense of the present invention, an optically variable security element is understood as an optical element of which the visual
Valuable documents in the sense of the present invention are, for example, banknotes, shares, loan documents, certificates, coupons, checks, lottery tickets, high-value entry tickets, passports, identity papers, credit cards and other flat articles of value.
Such articles of value can, however, also be packaging for possibly high-value products. The term security paper in the sense of the present invention comprises precursor stages of such valuable documents which, for example, are not suitable to be circulated. The security paper can be present in quasi endless form and processed further at a later time.
Such valuable documents are often provided with security elements as a safeguard, which permit the authenticity of the valuable documents to be checked and at the same time serve as a safeguard against forbidden reproduction. In order to increase security against forgery and to make imitation more difficult, such valuable documents comprising security elements are frequently covered with a further printed image.
The optically variable security element can already be part of the security paper used for the production.
The security element used is, for example, optically variable elements, whereby, in the sense of the present invention, an optically variable security element is understood as an optical element of which the visual
- 2 - PCT/EP2010/056496 impression given to an observer depends on the viewing direction, which means the viewing angle of the observer onto the optical element and possibly also the direction of incidence of any illuminating light beam.
In order that the optically variable effect can be detected, which means can be perceived visually by an observer or detected by a machine, the optically variable element must either be arranged directly on the substrate surface of the security paper or it may be covered only by layers having a sufficiently high transparency. Therefore, it is generally a problem if, for example in order to produce a valuable document, the security paper is to be printed with one or more further printed layers above such an optically variable security element, since in this case the ability to detect the optically variable effect can be impaired or prevented completely. In order nevertheless to ensure the ability to detect the optically variable effect, a recess in the region of the optically variable security element could be provided in the further printed layer.
However, this would firstly impair the stylistic freedom of the printed image to be applied. Secondly, this would lead to a clearly visible edge in the printed image additionally to be applied, which would interfere with the optical impression of the valuable document and is therefore undesired.
This is additionally problematic if the exact position of the optically variable security element on the substrate surface can vary, as is the case for example in security threads, which quite possibly have intentional registration fluctuations. In such a case, the recess would have to cover all the possible positions of the optically variable security element in order to ensure the ability to detect the optically variable effect, which would lead to a very large recess in the printed image to be applied.
In order that the optically variable effect can be detected, which means can be perceived visually by an observer or detected by a machine, the optically variable element must either be arranged directly on the substrate surface of the security paper or it may be covered only by layers having a sufficiently high transparency. Therefore, it is generally a problem if, for example in order to produce a valuable document, the security paper is to be printed with one or more further printed layers above such an optically variable security element, since in this case the ability to detect the optically variable effect can be impaired or prevented completely. In order nevertheless to ensure the ability to detect the optically variable effect, a recess in the region of the optically variable security element could be provided in the further printed layer.
However, this would firstly impair the stylistic freedom of the printed image to be applied. Secondly, this would lead to a clearly visible edge in the printed image additionally to be applied, which would interfere with the optical impression of the valuable document and is therefore undesired.
This is additionally problematic if the exact position of the optically variable security element on the substrate surface can vary, as is the case for example in security threads, which quite possibly have intentional registration fluctuations. In such a case, the recess would have to cover all the possible positions of the optically variable security element in order to ensure the ability to detect the optically variable effect, which would lead to a very large recess in the printed image to be applied.
- 3 - PCT/EP2010/056496 In order to increase the ink-receiving capacity for a printing ink forming such a printed image, which is advantageous in the case of film composite banknotes, for example, or in order to configure the ink-receiving capacity of the substrate surface of the security paper in a uniform manner, which is advantageous in the case of paper banknotes with an optically variable security element applied or incorporated, for example, it is further known to provide an ink-receiving or print-receiving layer on the substrate surface of the security paper. In order to obtain an ink-receiving capacity to the desired extent, it is frequently necessary to provide the ink-receiving layer with a layer thickness which has a matting effect. This matting effect is barely disruptive outside optically variable security elements. Above optically variable security elements, the optically variable effect thereof can, however, be reduced or suppressed entirely as a result.
It is therefore an object of the present invention to specify a security paper on which a printed image can be applied over the entire area in order to produce a valuable document, wherein at the same time a sufficient ability to detect the optically variable effect of an optically variable security element arranged in the security paper is ensured. It is also an object of the present invention to specify a method for producing such a security paper, an apparatus for implementing the production method and also a valuable document produced from the security paper.
This object is achieved by a security paper, a valuable document, a production method and an apparatus for implementing the production method having the features of the independent claims. The dependent claims relate to preferred refinements and developments of the invention.
The security paper according to the invention for producing valuable documents comprises a substrate having an optically variable security element, which can be detected when at least a first side of the substrate is observed, and an ink-receiving layer, which is arranged on the first side of the substrate in front of the optically variable security element in the viewing direction, wherein the ink-receiving layer has a first layer thickness in a first area of the substrate surface, which is located outside the area in which the optically variable security element is arranged, and a recess or a reduced layer thickness as compared with the first layer thickness in a second area of the substrate surface, which circumscribes the area in which the optically variable security element is or possibly can be located.
In the sense of the present invention, a detectable optically variable security element is understood to mean an optical element the optically variable effect of which can be detected by a machine or perceived visually by an observer. Examples of such optically variable security elements are diffraction structures which, in particular by means of the reconstruction of optically perceivable patterns, generate a visual impression that depends on viewing angle, such as embossed or volume holograms and other kinegrams such as achromatic matt structures. A further example of such optically variable elements is optical elements which exhibit what is known as a color tilt effect, such as single-layer or multilayer thin layer interference layers or liquid crystal layers, which can in each case be present as a continuous layer or in pigment form (what are known as effect pigments, such as iriodine) Further examples are lens or micro--mirror structures within the optically variable element.
Single-layer or multilayer substrates can be used as security paper. In the case of single-layer substrates, any type of paper or paper-like material is suitable, in particular cotton-vellum paper. It is also possible to use paper which contains a certain proportion x of a polymer material in the range between 0 and 100% by weight. Furthermore, a plastic film, for example a polyester film, can be used as substrate.
This film can additionally be monoaxially or biaxially oriented. Such an orientation of the film leads, amongst other things, to it being given polarizing characteristics, which are used as a further security feature in the optically variable security element.
A multilayer composite which, for example, has a layer of paper or paper-like material can be used as a multilayer substrate. A transparent plastic or polymer layer is laminated onto this layer, for example from both sides, which means that such a multilayer composite exhibits extraordinarily high stability and durability. In this case, security papers with plastic-coated or polymer-coated paper layers are used for producing film composite banknotes. Conversely, the multilayer composite can also have a central layer made of a plastic or polymer material, which is coated on both sides with a layer of paper or of paper-like material in each case. A multilayer, paper-free composite material can also be used as a multi_layer substrate material.
The materials used in such single-layer or multilayer substrates can have additives which serve as a further authenticity feature, such as luminescent substances, which are preferably transparent in the visible wavelength range and can be excited in the non-visible wavelength range by a suitable auxiliary means, for example a radiation source emitting UV or IR radiation, in order to generate luminescence that is visible or at least detectable by auxiliary means.
In the case of a film composite banknote the surface of which is formed by a plastic or polymer layer, for example, which has only a low ink-receiving capacity, the ink-receiving capacity can be improved by the use of an additional print-receiving or ink-receiving layer, or an adequate ink-receiving capacity for the printing ink of the printed image additionally to be applied can be created for the first time.
In the sense of the present invention, the term ink-receiving layer is also understood to mean layers which promote improved adhesion to the substrate surface, in particular to the plastic or polymer layer of a film composite banknote. The ink-receiving layer can also be built up from a plurality of partial layers. For example, a partial layer arranged directly on the substrate surface primarily promotes increased adhesion of a further partial layer to the security paper, while the further partial layer primarily ensures the ink-receiving capacity of the printing ink forming the further printed image. The partial layer arranged directly on the substrate surface and having an adhesive capacity is also designated a primer layer.
The printing ink of the ink-receiving layer and the partial layers possibly present is preferably composed of silica gel, a flow additive, a crosslinker and a binding agent.
Such ink-receiving layers are substantially colorless and frequently exhibit a matting effect with increasing layer thickness. Typically, an ink-receiving layer is applied to the entire surface of the substrate and - at least in the first substrate area in the sense of the invention - has a constant layer thickness. Ideally, the ink-receiving layer has no detectable structures and imparts no information to the observer - as opposed to other colored layers - for example in the form of characters, graphic symbols or colors. An ink-receiving layer in the sense of the invention instead forms a visually inconspicuous uniform base for the printing ink of a further printed image, for example to be applied in order to produce a valuable document.
The further printed image can be applied with the aid of the offset process or another suitable printing process. It can also be a background print:.
In the case of a paper banknote which is composed of a single-layer substrate made of paper or paper-like material, the optically variable security element is at least partly arranged on the surface of the substrate and, for example, comprises a film element. Thus, the substrate surface of the security paper has different materials area by area and correspondingly different ink-receiving capacities. As a result of the use of an ink-receiving layer, a uniform ink-receiving capacity of the substrate surface of a paper banknote can be ensured and, if appropriate, the ink-receiving capacity thereof can be increased.
The security element can be produced directly on the substrate of a security paper or a valuable document to be secured, or pro-prepared on a separate carrier.
Such a separate carrier preferably has plastic or polymer material and, for example, can be or have a film material, in particular a transfer material.
Plastics such as PET (polyethylene terephthalate), PUT
(polybutylene terephthalate), PEN (polyethylene naphthalate), PP (polypropylene), PA (polyamide) and PE
(polyethylene) are suitable for the film material.
This film can also be monoaxially or biaxially oriented.
The security element forms a transfer element and can be applied in endless form to a carrier material.
Here, the security element is fixed to the substrate with the aid of an adhesive layer, a hot-melt adhesive preferably being used for this purpose. Following the transfer of the security element to the substrate, the carrier material is possibly pulled off again, so that:
only the security element remains on the substrate.
The optically variable security element can be formed as a patch or label and, for example, have a two-dimensional form, with comparable length dimensions in all directions on the substrate surface, or an elongated form, for example the form of a strip, as in the case of security threads. If such an optically variable security element is formed as a transfer element with a possibly transparent film as carrier element, then it is also designated a film element, film patch or film strip. Such a strip is applied to the surface of a substrate, for example, in the form of what is known as a lead strip. Film elements can also be applied over a recess in the form of a hole in the substrate and thus be used as a hole covering, which at the same time ensures visibility of the optically variable security element from both sides of the substrate. On the other hand, the optically variable security element can also be partly embedded in the substrate material, for example in the form of a security thread, and come to the surface only in some areas, as is the case, for example, in what are known as window security threads, in which the security thread comes to the surface on only one side of the substrate, in some areas and possibly periodically, and what are known as pendulum security threads, in which the security thread comes to the surface alternately on both sides of the substrate.
In the case of multilayer substrates, such as film composite banknotes, the optically variable security element is arranged on the central layer made of paper or paper-like material or embedded in the latter. The optically variable security element is thus located within the two plastic or polymer layers laminated on both sides and is protected by said layers. Here, these two plastic or polymer layers laminated on exhibit a sufficiently high transparency, which ensures an adequate ability to detect the optically variable effect of the optically variable security element.
Thus, the optically variable security element: is arranged behind the transparent plastic or polymer layer in the viewing direction, and the ink-receiving layer is arranged in front of the transparent layer in the viewing direction.
The exact position of the optically variable security element in the substrate of the security paper is often not defined exactly and/or exhibits fluctuations. Such registration fluctuations are entirely intended, for example in the case of security threads, since the security thread gives rise to a thickening of the substrate material. To improve the stacking capacity of valuable documents having security threads, for example banknotes, it is therefore advantageous if the position of the security thread varies at right angles to the longitudinal direction of the security thread.
The overall area in which the security thread can come to lie is also designated a wobble area, and this area is understood as a second substrate area in the sense of the present invention.
As a result of the use according to the invention of a reduced layer thickness of the ink-receiving layer in this second substrate area, firstly the matting which results from the use of the ink-receiving layer is reduced and therefore the ability to detect the optically variable effect is already improved. In addition, the reduced layer thickness of the ink-receiving layer in the second substrate area results in a reduced ink-receiving capacity of the substrate surface of the security thread, which also means that the level of coverage of a layer of printing ink forming a printed image to be applied is reduced and also, as a result, the ability to detect the optically variable effect of the optically variable security element lying underneath is improved. The layer thickness within the second substrate area can diminish to zero, with which a complete recess in the ink-receiving layer is created in the second substrate area. In this case, the ink-receiving capacity depends on the surface properties of the substrate of the security paper which, in particular in the case of film composite banknotes, the surface of which is formed by a plastic or polymer layer, is very low.
The present invention is based on the finding that the optically variable effect of an optically variable security element can still be detected if an ink-receiving layer with reduced layer thickness and an ink layer with a correspondingly reduced level of coverage are located in front of the optically variable element in the viewing direction.
Advantageously, the further printed image to be applied during the production of the valuable document can be printed over the entire area, without taking any account of the position of the optically variable security element in the substrate of the security paper, by which means the production process is simplified and the stylistic freedom for the further printed image increases.
Advantageously, the ink-receiving layer is applied to the substrate of the security paper by gravure printing. The printing form used for this purpose, for example a press cylinder or printing plate, has a first and a second printing area which, during the gravure printing, in each case come to lie in the first and second substrate area of the security paper. The second printing area of the printing form has a printing ink receiving capacity for the printing ink from which the ink-receiving layer is produced that is reduced compared with the first printing area.
The printing ink receiving capacity is established by using depressions in the printing form. These depressions can be milled, for example by means of a CNC machine, as is usual in steel gravure printing, or etched, as is usual in intaglio printing.
In an advantageous embodiment, the depressions are present in the form of cells, and the second printing area has a cell size that is reduced as compared with the first printing area, an increased cell spacing and/or a reduced cell depth.
In an advantageous refinement of the security paper according to the invention, the layer thickness of the ink-receiving layer within the second substrate area, starting from the first layer thickness in the first substrate area, has a course which decreases in the form of a staircase or continuously, preferably with a constant gradient.
The course of the layer thickness of the ink-receiving layer, decreasing in the form of a staircase or continuously in the second substrate area, follows seamlessly on from the first layer thickness in the first substrate area. Such a course, having a three-dimensional gradient, has the advantage that, in the edge region between the first and the second substrate area, no disruptive edges occur which impair the optical impression of the valuable document to be produced. In the case of a course of the layer thickness that decreases in the form of a staircase within the second substrate area, the step height of the staircase-like course is preferably chosen to be so small that these steps are imperceptible to an observer.
In order to produce such a gradually decreasing course of the layer thickness of the ink-receiving layer within the second substrate area, the printing form has a corresponding gradual course in the printing ink receiving capacity in the second printing area thereof.
This can be ensured by a corresponding configuration of the depressions in the printing form. If the printing form has depressions in the form of cells, then the cell size is reduced gradually, the cell spacing is increased gradually and/or the cell depth is reduced gradually. The gradual course of cell size, cell spacing and/or cell depth can be configured to be continuous. The production of the printing form is simplified if the course of the printing ink receiving capacity of the printing form has a constant gradient, in which cell size, cell spacing and/or cell depth are preferably varied with a constant gradient.
The production of the printing form is also simplified if, additionally or alternatively, the printing ink receiving capacity of the printing form has a course that is staircase-like and thus constant in some areas.
The depressions in the printing form are configured in such a way that, in some areas, a uniform printing ink receiving capacity is achieved, areas having a different, gradually decreasing printing ink receiving capacity being arranged immediately beside one another.
The printing ink receiving capacity of directly adjacent areas preferably differs only slightly, so that the step height of the staircase-like course is so small that these cannot be perceived visually by an observer in the resultant ink-receiving layer. In the case of a staircase-like course, the gradient results from the positions and heights of the steps.
In a particularly preferred refinement, a multilayer ink-receiving layer is printed onto the substrate of the security paper in that a plurality of printing forms, preferably a plurality of press cylinders arranged one after another, in each case print a partial layer of the ink-receiving layer onto the substrate of the security paper. Here, each printing form has the above-described staircase-like course of the printing ink receiving capacity. The position of the steps of the respective staircase-like courses is, however, offset relative to one another in the various printing forms, so that an ink-receiving layer is produced on the substrate which has a high number of steps each having a low step height. The number of steps of the layer thickness of the ink-receiving layer on the substrate of the security paper is equal to the sum of the steps of the staircase-like course of the printing ink receiving capacity over all the printing forms used. This has the advantage that, by using only a few graduations in the printing ink receiving capacity in each of the printing forms, a high number of steps can be produced in the layer thickness of the ink-receiving layer on the substrate of the security paper, which firstly simplifies the production of the printing forms and secondly reduces or completely suppresses the visual perceptibility of the staircase-like course of the layer thickness of the ink-receiving layer on the substrate. With the aid of such a multilayer ink-receiving layer, it is additionally possible, in particular in the first substrate area, to achieve improved homogeneity of the ink-receiving layer and of the printed image to be applied.
The layer thickness of the ink-receiving layer within the second substrate area has a minimum value. This minimum value can be zero or different from zero and, for example, can amount to 25% of the first layer thickness in the first substrate area. This minimum value can be assumed in a two-dimensional area within the second substrate area. If the second substrate area has an elongated shape, as is true for example in the case of a security thread as an optically variable security element, then the minimum value of the layer thickness within the second substrate area is =
a preferably assumed only in a linear area. If the second substrate area has comparable length dimensions in all directions on the substrate surface, as is true for example in the case of a two-dimensional patch, then the layer thickness of the ink-receiving layer has the minimum value preferably only in a point-like area.
Advantageously, the course of the layer thickness of the ink-receiving layer is symmetrical with respect to the area in which the minimum value is assumed. This has the advantage that the perceptibility of the gradual course of the layer thickness within the second substrate area is reduced further.
In an advantageous refinement, the security paper forms the precursor stage of a film composite banknote. In this case, a transparent plastic or polymer film is laminated onto both sides of a central layer made of a paper or a paper-like material. The optically variable security element is arranged in the area of the central layer of paper or paper-like material and is thus located behind the transparent plastic or polymer layer in the viewing direction. The ink-receiving layer is arranged directly on this transparent layer and is therefore in front of the transparent layer in the viewing direction.
In a further preferred refinement of the document, the optically variable security element can also be perceived visually when observing a second side of the substrate, located opposite the first side of the substrate. This can be implemented, for example, by means of a pendulum security thread, which can be detected section by section from the front side and reverse of a valuable document, or else by means of a security element which forms a hole covering of a recess in the substrate.
Further exemplary embodiments and advantages of the invention will be explained below by way of example by using the accompanying figures. The examples constitute preferred embodiments, which in no way restrict the invention. The figures shown are schematic representations which do not reflect the real proportions but are used for improved clarity of the various exemplary embodiments.
In detail:
Fig. 1 shows a banknote having an optically variable security element;
Fig. 2 shows a cross section through a first exemplary embodiment of a security paper having an ink-receiving layer;
Fig. 3 shows a cross section through a second exemplary embodiment of a security paper having an ink-receiving layer; and Fig. 4 shows a cylindrical press cylinder.
In fig. 1, a banknote 1 is illustrated as a valuable document, having a window security thread 2 as optically variable security element. The security thread 2 has a strip width of 3 to 5 man and, as a result of registration fluctuations, is located at an arbitrary point within what is known as the wobble area 3, which has a strip width of about 1 cm.
In fig. 2, a first exemplary embodiment of a security paper 7, which is used to produce a film composite banknote 1 as illustrated in fig. 1, is illustrated in cross section along the line A-A' in fig. 1. The substrate 8 of the security paper 7 comprises a central paper layer 4 and transparent PET films 5 laminated onto both sides. Also illustrated is the security thread 2, which, in the sectional drawing shown (along the line A-A'), comes to the surface of the paper layer
It is therefore an object of the present invention to specify a security paper on which a printed image can be applied over the entire area in order to produce a valuable document, wherein at the same time a sufficient ability to detect the optically variable effect of an optically variable security element arranged in the security paper is ensured. It is also an object of the present invention to specify a method for producing such a security paper, an apparatus for implementing the production method and also a valuable document produced from the security paper.
This object is achieved by a security paper, a valuable document, a production method and an apparatus for implementing the production method having the features of the independent claims. The dependent claims relate to preferred refinements and developments of the invention.
The security paper according to the invention for producing valuable documents comprises a substrate having an optically variable security element, which can be detected when at least a first side of the substrate is observed, and an ink-receiving layer, which is arranged on the first side of the substrate in front of the optically variable security element in the viewing direction, wherein the ink-receiving layer has a first layer thickness in a first area of the substrate surface, which is located outside the area in which the optically variable security element is arranged, and a recess or a reduced layer thickness as compared with the first layer thickness in a second area of the substrate surface, which circumscribes the area in which the optically variable security element is or possibly can be located.
In the sense of the present invention, a detectable optically variable security element is understood to mean an optical element the optically variable effect of which can be detected by a machine or perceived visually by an observer. Examples of such optically variable security elements are diffraction structures which, in particular by means of the reconstruction of optically perceivable patterns, generate a visual impression that depends on viewing angle, such as embossed or volume holograms and other kinegrams such as achromatic matt structures. A further example of such optically variable elements is optical elements which exhibit what is known as a color tilt effect, such as single-layer or multilayer thin layer interference layers or liquid crystal layers, which can in each case be present as a continuous layer or in pigment form (what are known as effect pigments, such as iriodine) Further examples are lens or micro--mirror structures within the optically variable element.
Single-layer or multilayer substrates can be used as security paper. In the case of single-layer substrates, any type of paper or paper-like material is suitable, in particular cotton-vellum paper. It is also possible to use paper which contains a certain proportion x of a polymer material in the range between 0 and 100% by weight. Furthermore, a plastic film, for example a polyester film, can be used as substrate.
This film can additionally be monoaxially or biaxially oriented. Such an orientation of the film leads, amongst other things, to it being given polarizing characteristics, which are used as a further security feature in the optically variable security element.
A multilayer composite which, for example, has a layer of paper or paper-like material can be used as a multilayer substrate. A transparent plastic or polymer layer is laminated onto this layer, for example from both sides, which means that such a multilayer composite exhibits extraordinarily high stability and durability. In this case, security papers with plastic-coated or polymer-coated paper layers are used for producing film composite banknotes. Conversely, the multilayer composite can also have a central layer made of a plastic or polymer material, which is coated on both sides with a layer of paper or of paper-like material in each case. A multilayer, paper-free composite material can also be used as a multi_layer substrate material.
The materials used in such single-layer or multilayer substrates can have additives which serve as a further authenticity feature, such as luminescent substances, which are preferably transparent in the visible wavelength range and can be excited in the non-visible wavelength range by a suitable auxiliary means, for example a radiation source emitting UV or IR radiation, in order to generate luminescence that is visible or at least detectable by auxiliary means.
In the case of a film composite banknote the surface of which is formed by a plastic or polymer layer, for example, which has only a low ink-receiving capacity, the ink-receiving capacity can be improved by the use of an additional print-receiving or ink-receiving layer, or an adequate ink-receiving capacity for the printing ink of the printed image additionally to be applied can be created for the first time.
In the sense of the present invention, the term ink-receiving layer is also understood to mean layers which promote improved adhesion to the substrate surface, in particular to the plastic or polymer layer of a film composite banknote. The ink-receiving layer can also be built up from a plurality of partial layers. For example, a partial layer arranged directly on the substrate surface primarily promotes increased adhesion of a further partial layer to the security paper, while the further partial layer primarily ensures the ink-receiving capacity of the printing ink forming the further printed image. The partial layer arranged directly on the substrate surface and having an adhesive capacity is also designated a primer layer.
The printing ink of the ink-receiving layer and the partial layers possibly present is preferably composed of silica gel, a flow additive, a crosslinker and a binding agent.
Such ink-receiving layers are substantially colorless and frequently exhibit a matting effect with increasing layer thickness. Typically, an ink-receiving layer is applied to the entire surface of the substrate and - at least in the first substrate area in the sense of the invention - has a constant layer thickness. Ideally, the ink-receiving layer has no detectable structures and imparts no information to the observer - as opposed to other colored layers - for example in the form of characters, graphic symbols or colors. An ink-receiving layer in the sense of the invention instead forms a visually inconspicuous uniform base for the printing ink of a further printed image, for example to be applied in order to produce a valuable document.
The further printed image can be applied with the aid of the offset process or another suitable printing process. It can also be a background print:.
In the case of a paper banknote which is composed of a single-layer substrate made of paper or paper-like material, the optically variable security element is at least partly arranged on the surface of the substrate and, for example, comprises a film element. Thus, the substrate surface of the security paper has different materials area by area and correspondingly different ink-receiving capacities. As a result of the use of an ink-receiving layer, a uniform ink-receiving capacity of the substrate surface of a paper banknote can be ensured and, if appropriate, the ink-receiving capacity thereof can be increased.
The security element can be produced directly on the substrate of a security paper or a valuable document to be secured, or pro-prepared on a separate carrier.
Such a separate carrier preferably has plastic or polymer material and, for example, can be or have a film material, in particular a transfer material.
Plastics such as PET (polyethylene terephthalate), PUT
(polybutylene terephthalate), PEN (polyethylene naphthalate), PP (polypropylene), PA (polyamide) and PE
(polyethylene) are suitable for the film material.
This film can also be monoaxially or biaxially oriented.
The security element forms a transfer element and can be applied in endless form to a carrier material.
Here, the security element is fixed to the substrate with the aid of an adhesive layer, a hot-melt adhesive preferably being used for this purpose. Following the transfer of the security element to the substrate, the carrier material is possibly pulled off again, so that:
only the security element remains on the substrate.
The optically variable security element can be formed as a patch or label and, for example, have a two-dimensional form, with comparable length dimensions in all directions on the substrate surface, or an elongated form, for example the form of a strip, as in the case of security threads. If such an optically variable security element is formed as a transfer element with a possibly transparent film as carrier element, then it is also designated a film element, film patch or film strip. Such a strip is applied to the surface of a substrate, for example, in the form of what is known as a lead strip. Film elements can also be applied over a recess in the form of a hole in the substrate and thus be used as a hole covering, which at the same time ensures visibility of the optically variable security element from both sides of the substrate. On the other hand, the optically variable security element can also be partly embedded in the substrate material, for example in the form of a security thread, and come to the surface only in some areas, as is the case, for example, in what are known as window security threads, in which the security thread comes to the surface on only one side of the substrate, in some areas and possibly periodically, and what are known as pendulum security threads, in which the security thread comes to the surface alternately on both sides of the substrate.
In the case of multilayer substrates, such as film composite banknotes, the optically variable security element is arranged on the central layer made of paper or paper-like material or embedded in the latter. The optically variable security element is thus located within the two plastic or polymer layers laminated on both sides and is protected by said layers. Here, these two plastic or polymer layers laminated on exhibit a sufficiently high transparency, which ensures an adequate ability to detect the optically variable effect of the optically variable security element.
Thus, the optically variable security element: is arranged behind the transparent plastic or polymer layer in the viewing direction, and the ink-receiving layer is arranged in front of the transparent layer in the viewing direction.
The exact position of the optically variable security element in the substrate of the security paper is often not defined exactly and/or exhibits fluctuations. Such registration fluctuations are entirely intended, for example in the case of security threads, since the security thread gives rise to a thickening of the substrate material. To improve the stacking capacity of valuable documents having security threads, for example banknotes, it is therefore advantageous if the position of the security thread varies at right angles to the longitudinal direction of the security thread.
The overall area in which the security thread can come to lie is also designated a wobble area, and this area is understood as a second substrate area in the sense of the present invention.
As a result of the use according to the invention of a reduced layer thickness of the ink-receiving layer in this second substrate area, firstly the matting which results from the use of the ink-receiving layer is reduced and therefore the ability to detect the optically variable effect is already improved. In addition, the reduced layer thickness of the ink-receiving layer in the second substrate area results in a reduced ink-receiving capacity of the substrate surface of the security thread, which also means that the level of coverage of a layer of printing ink forming a printed image to be applied is reduced and also, as a result, the ability to detect the optically variable effect of the optically variable security element lying underneath is improved. The layer thickness within the second substrate area can diminish to zero, with which a complete recess in the ink-receiving layer is created in the second substrate area. In this case, the ink-receiving capacity depends on the surface properties of the substrate of the security paper which, in particular in the case of film composite banknotes, the surface of which is formed by a plastic or polymer layer, is very low.
The present invention is based on the finding that the optically variable effect of an optically variable security element can still be detected if an ink-receiving layer with reduced layer thickness and an ink layer with a correspondingly reduced level of coverage are located in front of the optically variable element in the viewing direction.
Advantageously, the further printed image to be applied during the production of the valuable document can be printed over the entire area, without taking any account of the position of the optically variable security element in the substrate of the security paper, by which means the production process is simplified and the stylistic freedom for the further printed image increases.
Advantageously, the ink-receiving layer is applied to the substrate of the security paper by gravure printing. The printing form used for this purpose, for example a press cylinder or printing plate, has a first and a second printing area which, during the gravure printing, in each case come to lie in the first and second substrate area of the security paper. The second printing area of the printing form has a printing ink receiving capacity for the printing ink from which the ink-receiving layer is produced that is reduced compared with the first printing area.
The printing ink receiving capacity is established by using depressions in the printing form. These depressions can be milled, for example by means of a CNC machine, as is usual in steel gravure printing, or etched, as is usual in intaglio printing.
In an advantageous embodiment, the depressions are present in the form of cells, and the second printing area has a cell size that is reduced as compared with the first printing area, an increased cell spacing and/or a reduced cell depth.
In an advantageous refinement of the security paper according to the invention, the layer thickness of the ink-receiving layer within the second substrate area, starting from the first layer thickness in the first substrate area, has a course which decreases in the form of a staircase or continuously, preferably with a constant gradient.
The course of the layer thickness of the ink-receiving layer, decreasing in the form of a staircase or continuously in the second substrate area, follows seamlessly on from the first layer thickness in the first substrate area. Such a course, having a three-dimensional gradient, has the advantage that, in the edge region between the first and the second substrate area, no disruptive edges occur which impair the optical impression of the valuable document to be produced. In the case of a course of the layer thickness that decreases in the form of a staircase within the second substrate area, the step height of the staircase-like course is preferably chosen to be so small that these steps are imperceptible to an observer.
In order to produce such a gradually decreasing course of the layer thickness of the ink-receiving layer within the second substrate area, the printing form has a corresponding gradual course in the printing ink receiving capacity in the second printing area thereof.
This can be ensured by a corresponding configuration of the depressions in the printing form. If the printing form has depressions in the form of cells, then the cell size is reduced gradually, the cell spacing is increased gradually and/or the cell depth is reduced gradually. The gradual course of cell size, cell spacing and/or cell depth can be configured to be continuous. The production of the printing form is simplified if the course of the printing ink receiving capacity of the printing form has a constant gradient, in which cell size, cell spacing and/or cell depth are preferably varied with a constant gradient.
The production of the printing form is also simplified if, additionally or alternatively, the printing ink receiving capacity of the printing form has a course that is staircase-like and thus constant in some areas.
The depressions in the printing form are configured in such a way that, in some areas, a uniform printing ink receiving capacity is achieved, areas having a different, gradually decreasing printing ink receiving capacity being arranged immediately beside one another.
The printing ink receiving capacity of directly adjacent areas preferably differs only slightly, so that the step height of the staircase-like course is so small that these cannot be perceived visually by an observer in the resultant ink-receiving layer. In the case of a staircase-like course, the gradient results from the positions and heights of the steps.
In a particularly preferred refinement, a multilayer ink-receiving layer is printed onto the substrate of the security paper in that a plurality of printing forms, preferably a plurality of press cylinders arranged one after another, in each case print a partial layer of the ink-receiving layer onto the substrate of the security paper. Here, each printing form has the above-described staircase-like course of the printing ink receiving capacity. The position of the steps of the respective staircase-like courses is, however, offset relative to one another in the various printing forms, so that an ink-receiving layer is produced on the substrate which has a high number of steps each having a low step height. The number of steps of the layer thickness of the ink-receiving layer on the substrate of the security paper is equal to the sum of the steps of the staircase-like course of the printing ink receiving capacity over all the printing forms used. This has the advantage that, by using only a few graduations in the printing ink receiving capacity in each of the printing forms, a high number of steps can be produced in the layer thickness of the ink-receiving layer on the substrate of the security paper, which firstly simplifies the production of the printing forms and secondly reduces or completely suppresses the visual perceptibility of the staircase-like course of the layer thickness of the ink-receiving layer on the substrate. With the aid of such a multilayer ink-receiving layer, it is additionally possible, in particular in the first substrate area, to achieve improved homogeneity of the ink-receiving layer and of the printed image to be applied.
The layer thickness of the ink-receiving layer within the second substrate area has a minimum value. This minimum value can be zero or different from zero and, for example, can amount to 25% of the first layer thickness in the first substrate area. This minimum value can be assumed in a two-dimensional area within the second substrate area. If the second substrate area has an elongated shape, as is true for example in the case of a security thread as an optically variable security element, then the minimum value of the layer thickness within the second substrate area is =
a preferably assumed only in a linear area. If the second substrate area has comparable length dimensions in all directions on the substrate surface, as is true for example in the case of a two-dimensional patch, then the layer thickness of the ink-receiving layer has the minimum value preferably only in a point-like area.
Advantageously, the course of the layer thickness of the ink-receiving layer is symmetrical with respect to the area in which the minimum value is assumed. This has the advantage that the perceptibility of the gradual course of the layer thickness within the second substrate area is reduced further.
In an advantageous refinement, the security paper forms the precursor stage of a film composite banknote. In this case, a transparent plastic or polymer film is laminated onto both sides of a central layer made of a paper or a paper-like material. The optically variable security element is arranged in the area of the central layer of paper or paper-like material and is thus located behind the transparent plastic or polymer layer in the viewing direction. The ink-receiving layer is arranged directly on this transparent layer and is therefore in front of the transparent layer in the viewing direction.
In a further preferred refinement of the document, the optically variable security element can also be perceived visually when observing a second side of the substrate, located opposite the first side of the substrate. This can be implemented, for example, by means of a pendulum security thread, which can be detected section by section from the front side and reverse of a valuable document, or else by means of a security element which forms a hole covering of a recess in the substrate.
Further exemplary embodiments and advantages of the invention will be explained below by way of example by using the accompanying figures. The examples constitute preferred embodiments, which in no way restrict the invention. The figures shown are schematic representations which do not reflect the real proportions but are used for improved clarity of the various exemplary embodiments.
In detail:
Fig. 1 shows a banknote having an optically variable security element;
Fig. 2 shows a cross section through a first exemplary embodiment of a security paper having an ink-receiving layer;
Fig. 3 shows a cross section through a second exemplary embodiment of a security paper having an ink-receiving layer; and Fig. 4 shows a cylindrical press cylinder.
In fig. 1, a banknote 1 is illustrated as a valuable document, having a window security thread 2 as optically variable security element. The security thread 2 has a strip width of 3 to 5 man and, as a result of registration fluctuations, is located at an arbitrary point within what is known as the wobble area 3, which has a strip width of about 1 cm.
In fig. 2, a first exemplary embodiment of a security paper 7, which is used to produce a film composite banknote 1 as illustrated in fig. 1, is illustrated in cross section along the line A-A' in fig. 1. The substrate 8 of the security paper 7 comprises a central paper layer 4 and transparent PET films 5 laminated onto both sides. Also illustrated is the security thread 2, which, in the sectional drawing shown (along the line A-A'), comes to the surface of the paper layer
4 and can thus be detected from above when the security paper 7 in fig. 2 is observed. The security thread 2 shows an optically variable effect. In the exemplary embodiment shown in fig. 2, it is arranged centrally within the wobble area 3. However, its position varies arbitrarily within the wobble area 3 in the security paper 7 and thus from banknote 1 to banknote 1.
Applied to the surface of the PET film 5 shown at the top in fig. 2 is an ink-receiving layer 6. Outside the wobble area 3, said ink-receiving layer 6 has a first uniform layer thickness. Within the wobble area 3, the layer thickness of the ink-receiving layer 6 decreases continuously down to a minimum value, starting arom the edge region of the wobble area 3. Such an ink-receiving layer can be created by common coating and application methods, for example with the aid of a press cylinder in gravure printing, the printing ink receiving capacity of which, in an area which comes to lie on the wobble area 3 of the security paper 7 during the gravure printing, shows a correspondingly continuous course of the printing ink receiving capacity.
The second exemplary embodiment, shown in fig. 3, differs from the first exemplary embodiment, shown in fig. 2, in a course of the layer thickness of the ink-receiving layer 6 within the wobble area 3 that is like a staircase instead of continuous. An ink-receiving layer 6 configured in this way can in principle likewise be produced during gravure printing with the aid of a press cylinder which shows a correspondingly staircase-like course of the printing ink receiving capacity.
However, in the exemplary embodiment illustrated in fig. 3, the print-receiving layer 6, at least outside the wobble area 3, comprises three partial layers 6a, 6b, 6c, which each have a layer thickness of about one third of the total layer thickness of the ink-receiving =
Applied to the surface of the PET film 5 shown at the top in fig. 2 is an ink-receiving layer 6. Outside the wobble area 3, said ink-receiving layer 6 has a first uniform layer thickness. Within the wobble area 3, the layer thickness of the ink-receiving layer 6 decreases continuously down to a minimum value, starting arom the edge region of the wobble area 3. Such an ink-receiving layer can be created by common coating and application methods, for example with the aid of a press cylinder in gravure printing, the printing ink receiving capacity of which, in an area which comes to lie on the wobble area 3 of the security paper 7 during the gravure printing, shows a correspondingly continuous course of the printing ink receiving capacity.
The second exemplary embodiment, shown in fig. 3, differs from the first exemplary embodiment, shown in fig. 2, in a course of the layer thickness of the ink-receiving layer 6 within the wobble area 3 that is like a staircase instead of continuous. An ink-receiving layer 6 configured in this way can in principle likewise be produced during gravure printing with the aid of a press cylinder which shows a correspondingly staircase-like course of the printing ink receiving capacity.
However, in the exemplary embodiment illustrated in fig. 3, the print-receiving layer 6, at least outside the wobble area 3, comprises three partial layers 6a, 6b, 6c, which each have a layer thickness of about one third of the total layer thickness of the ink-receiving =
5 - 17 - PCT/EP2010/056496 layer 6. Within the wobble area, the partial layers 6b and 6c have recesses, while the partial layer 6a has no recess and is applied to the entire area of the security paper V. Thus, in the second exemplary embodiment illustrated, within the wobble area a minimum value of the layer thickness of the ink-receiving layer 6 is assumed which corresponds to the layer thickness of the partial layer 6a, that is to say of about one third of the layer thickness outside the wobble area 3. The three partial layers 6a, 6b and 6c are applied by three different press cylinders DW1, DW2, DW3 to the banknote 1, the press cylinder which prints the partial layer 6a showing no recesses in the printing ink receiving capacity, the press cylinder which produces the partial layer 6b having a printing ink receiving capacity of zero in a printing area which is narrower than the wobble area 3, and the press cylinder which produces the partial layer 6c havinq a printing ink receiving capacity of zero in a printing area the width of which corresponds to the width of the wobble area 3. The three press cylinders are arranged suitably in relation to one another, so that the staircase-like course of the layer thickness of the print-receiving layer 6, illustrated in fig. 2, is produced within the wobble area 3. The upper partial layers 6b and 6c are primarily used to improve the reception of the printing ink forming the printed image still to be applied. They are also designated print-receiving layers. The lower partial layer 6a, arranged directly on the surface of the substrate 8, is primarily used to improve the mechanical adhesion of the partial layers 6b and 6c lying above to the substrate surface of the security paper. To this end, the partial layer 6a exhibits a suitable adhesive capacity. It is also designated a primer layer.
In an exemplary embodiment that is not illustrated, each of the three press cylinders has a staircase-like graduation of the printing ink receiving capacity. The printing ink receiving capacity in two of the three press cylinders DW2, DW3 has five graduations with 0, 25, 50, 75 or 100% of the maximum printing ink receiving capacity, which means that on each of these press cylinders four steps are produced during the transition from 100% to 0% printing ink receiving capacity. In the third press cylinder. DWI, the printing ink receiving capacity has only four graduations with 25, 50, 75 or 100% of the maximum printing ink receiving capacity, which means that in this press cylinder three steps are produced during the transition from 100% to 25% printing ink receiving capacity. The steps of the staircase-like courses of the three press cylinders are arranged offset suitably relative to one another, so that the resulting overall ink-receiving layer has a total of eleven steps that are uniform with respect to height and position. Here, the layer thickness of the ink-receiving layer decreases gradually from a unit-free value of 300 outside the wobble area 3 to a minimum value of 25.
The fine staircase-like graduation resulting from this in the layer thickness can no longer be perceived by an observer, by which means edges interfering optically with the visual impression of the resulting banknote 1 are avoided but, at the same time, the ability to detect the optically variable effect of the security thread 2 is ensured. The course of the printing ink receiving capacity of the three press cylinders DW1, DW2 and DW3 and also the resultant total layer thickness of the ink-receiving layer. 6 are reproduced numerically in the following table.
Total 300 300 300 275 250 225 200 175 150 125 100 75 50 25 In fig. 4, a press cylinder for gravure printing is illustrated perspectively. It contains depressions in the form of cells 9 for receiving the printing ink forming the ink-receiving layer 6. In a printing area 10, the size of the cells 9 decreases continuously down to a minimum value, and the printing ink receiving capacity of the press cylinder exhibits a corresponding three-dimensionally gradual course. During gravure printing, the printing area 10 comes to lie on the wobble area 3 of the security thread 2 of the security paper 7. The length of the printing area 10 in the 1.0 direction of the axis of the press cylinder is less than or equal to the width of the wobble area 3 on the substrate 8 of the security paper 7. By using the press cylinder illustrated, it is thus possible to produce an ink-receiving layer 6 which has a reduced layer thickness within the wobble area 3. In particular, as a result, to a good approximation continuous courses of the layer thickness of the ink-receiving layer 6 can be implemented within the wobble area 3. A plurality of press cylinders are preferably combined in order to implement a plurality of partial layers of the ink-receiving layer 6.
In an exemplary embodiment that is not illustrated, instead of a press cylinder, use is made of a printing plate having a correspondingly gradual course of the printing ink receiving capacity. While in the case of the press cylinder the gradual course of the printing ink receiving capacity is present only in the axial direction, the printing plate exhibits such a gradual course in various directions on the surface of the printing plate, it being possible for the gradients to be different in different directions. Thus, the area in which there is a gradual course of the printing ink receiving capacity on the printing plate can be matched to the shape of the optically variable security element to be overprinted. This permits, for example, the overprinting of an optically variable security element in the form of a two-dimensional patch or a label.
z ti In a further exemplary embodiment, not illustrated, the ink-receiving layer comprises a total of 4 partial layers, three print-receiving layers, which are primarily used to improve the reception (absorption) of the printing ink forming the printed image to be applied, and a primer layer, which is primarily used to improve the mechanical adhesion of the print-receiving layers to the substrate surface of the security paper, the substrate surface consisting of a PET film and the primer layer being arranged directly on the latter.
The three print-receiving layers have, besides one or various silica gels as flow additive, a longer-chain alcohol, for example Dowanoltype or tertiary butoxypropanol, pentaerythrityl glycidyl ether as cross linker, and an aqueous polyurethane or polyacrylate or urethane acrylate dispersion as binder. If appropriate, further additives such as waxes, surface additives, anti-foam additives can be used. The print-receiving layers have 0 - 5% crosslinker, 0 - 5% flow additive, 5 - 50%, preferably 10 - 25%, silica gel and 40 - 80%, preferably 65 - 75%, binder.
The composition of the three print-receiving layers can vary. For instance, the uppermost layer on the security paper has a lower quantity of silica gel than the layers lying underneath. This has the advantage that the uppermost print-receiving layer is stable with respect to abrasion and at the same time is still sufficiently porous to let the printing ink of the printed image to be applied through to the print-receiving layers lying underneath. The print-receiving layers lying underneath have higher proportions of silica gel and therefore act like a sponge, a possibly lower stability with respect to abrasion being of no consequence.
The primer layer likewise has, besides one or various silica gels as flow additive, a longer-chain alcohol, for example Dowanoltype or tertiary butoxypropanol, polyfunctional aziridine as crosslinker, and an aqueous acrylate, styrene acrylate or PU dispersion, for example Alberdingk U 520, as binder. The primer layer has 0 - 5% crosslinker, 0 - 1.0% flow additive, 0 - 20%, preferably 0 - 10%, silica gel, and 80 - 100%, preferably 85 - 90%, binder.
By means of a suitable, for example chemical, pre-treatment of the PET film of the security paper for a film composite banknote, adequate adhesion of the print-receiving layers can also be achieved directly on the PET film, which means that the primer layer can be dispensed with.
In an exemplary embodiment that is not illustrated, each of the three press cylinders has a staircase-like graduation of the printing ink receiving capacity. The printing ink receiving capacity in two of the three press cylinders DW2, DW3 has five graduations with 0, 25, 50, 75 or 100% of the maximum printing ink receiving capacity, which means that on each of these press cylinders four steps are produced during the transition from 100% to 0% printing ink receiving capacity. In the third press cylinder. DWI, the printing ink receiving capacity has only four graduations with 25, 50, 75 or 100% of the maximum printing ink receiving capacity, which means that in this press cylinder three steps are produced during the transition from 100% to 25% printing ink receiving capacity. The steps of the staircase-like courses of the three press cylinders are arranged offset suitably relative to one another, so that the resulting overall ink-receiving layer has a total of eleven steps that are uniform with respect to height and position. Here, the layer thickness of the ink-receiving layer decreases gradually from a unit-free value of 300 outside the wobble area 3 to a minimum value of 25.
The fine staircase-like graduation resulting from this in the layer thickness can no longer be perceived by an observer, by which means edges interfering optically with the visual impression of the resulting banknote 1 are avoided but, at the same time, the ability to detect the optically variable effect of the security thread 2 is ensured. The course of the printing ink receiving capacity of the three press cylinders DW1, DW2 and DW3 and also the resultant total layer thickness of the ink-receiving layer. 6 are reproduced numerically in the following table.
Total 300 300 300 275 250 225 200 175 150 125 100 75 50 25 In fig. 4, a press cylinder for gravure printing is illustrated perspectively. It contains depressions in the form of cells 9 for receiving the printing ink forming the ink-receiving layer 6. In a printing area 10, the size of the cells 9 decreases continuously down to a minimum value, and the printing ink receiving capacity of the press cylinder exhibits a corresponding three-dimensionally gradual course. During gravure printing, the printing area 10 comes to lie on the wobble area 3 of the security thread 2 of the security paper 7. The length of the printing area 10 in the 1.0 direction of the axis of the press cylinder is less than or equal to the width of the wobble area 3 on the substrate 8 of the security paper 7. By using the press cylinder illustrated, it is thus possible to produce an ink-receiving layer 6 which has a reduced layer thickness within the wobble area 3. In particular, as a result, to a good approximation continuous courses of the layer thickness of the ink-receiving layer 6 can be implemented within the wobble area 3. A plurality of press cylinders are preferably combined in order to implement a plurality of partial layers of the ink-receiving layer 6.
In an exemplary embodiment that is not illustrated, instead of a press cylinder, use is made of a printing plate having a correspondingly gradual course of the printing ink receiving capacity. While in the case of the press cylinder the gradual course of the printing ink receiving capacity is present only in the axial direction, the printing plate exhibits such a gradual course in various directions on the surface of the printing plate, it being possible for the gradients to be different in different directions. Thus, the area in which there is a gradual course of the printing ink receiving capacity on the printing plate can be matched to the shape of the optically variable security element to be overprinted. This permits, for example, the overprinting of an optically variable security element in the form of a two-dimensional patch or a label.
z ti In a further exemplary embodiment, not illustrated, the ink-receiving layer comprises a total of 4 partial layers, three print-receiving layers, which are primarily used to improve the reception (absorption) of the printing ink forming the printed image to be applied, and a primer layer, which is primarily used to improve the mechanical adhesion of the print-receiving layers to the substrate surface of the security paper, the substrate surface consisting of a PET film and the primer layer being arranged directly on the latter.
The three print-receiving layers have, besides one or various silica gels as flow additive, a longer-chain alcohol, for example Dowanoltype or tertiary butoxypropanol, pentaerythrityl glycidyl ether as cross linker, and an aqueous polyurethane or polyacrylate or urethane acrylate dispersion as binder. If appropriate, further additives such as waxes, surface additives, anti-foam additives can be used. The print-receiving layers have 0 - 5% crosslinker, 0 - 5% flow additive, 5 - 50%, preferably 10 - 25%, silica gel and 40 - 80%, preferably 65 - 75%, binder.
The composition of the three print-receiving layers can vary. For instance, the uppermost layer on the security paper has a lower quantity of silica gel than the layers lying underneath. This has the advantage that the uppermost print-receiving layer is stable with respect to abrasion and at the same time is still sufficiently porous to let the printing ink of the printed image to be applied through to the print-receiving layers lying underneath. The print-receiving layers lying underneath have higher proportions of silica gel and therefore act like a sponge, a possibly lower stability with respect to abrasion being of no consequence.
The primer layer likewise has, besides one or various silica gels as flow additive, a longer-chain alcohol, for example Dowanoltype or tertiary butoxypropanol, polyfunctional aziridine as crosslinker, and an aqueous acrylate, styrene acrylate or PU dispersion, for example Alberdingk U 520, as binder. The primer layer has 0 - 5% crosslinker, 0 - 1.0% flow additive, 0 - 20%, preferably 0 - 10%, silica gel, and 80 - 100%, preferably 85 - 90%, binder.
By means of a suitable, for example chemical, pre-treatment of the PET film of the security paper for a film composite banknote, adequate adhesion of the print-receiving layers can also be achieved directly on the PET film, which means that the primer layer can be dispensed with.
Claims (13)
1. A security paper for producing valuable documents, comprising a substrate having an optically variable security element, which can be detected when at least a first side of the substrate is observed, and an ink-receiving layer, which is arranged at least on the first side of the substrate, wherein the ink-receiving layer has a first layer thickness in a first substrate area lying outside the area of the optically variable security element and a recess or a reduced layer thickness compared to the first layer thickness in a second substrate area in which the optically variable security element is arranged.
2. The security paper as claimed in claim 1, characterized in that the layer thickness within the second substrate area, starting from the first layer thickness in the first substrate area, has a course which decreases in the form of a staircase or continuously, preferably with a constant gradient.
3. The security paper as claimed in claim 2, characterized in that the layer thickness has a minimum value within the second substrate area, preferably in a point-like or linear area.
4. The security paper as claimed in one of the preceding claims, characterized in that the substrate comprises a layer of paper or paper-like material, which is preferably coated, particularly preferably on both sides, with a transparent plastic or polymer layer.
5. The security paper as claimed in one of the preceding claims, characterized in that the security element of the security paper is formed as a security thread, preferably as a window security thread, as a film patch or as a film strip.
6. The security paper as claimed in one of the preceding claims, characterized in that the optically variable security element can also be detected when observing a second side of the substrate, located opposite the first side of the substrate, wherein the optically variable security element is preferably formed as a pendulum security thread or as a covering over a cut-out in the substrate.
7. A valuable document comprising a security paper as claimed in one of claims 1 to 6, wherein the valuable document has a printing ink layer arranged on the ink-receiving layer.
8. A method for producing a security paper for producing valuable documents, comprising the steps:
- providing a substrate having an optically variable security element which can be detected when at least a first side of the substrate is observed, and - applying an ink-receiving layer to at least the first side of the substrate in such a way that the ink-receiving layer has a first layer thickness in a first substrate area lying outside the area of the optically variable security element and a recess or a reduced layer thickness compared to the first layer thickness in a second substrate area in which the optically variable security element is arranged.
- providing a substrate having an optically variable security element which can be detected when at least a first side of the substrate is observed, and - applying an ink-receiving layer to at least the first side of the substrate in such a way that the ink-receiving layer has a first layer thickness in a first substrate area lying outside the area of the optically variable security element and a recess or a reduced layer thickness compared to the first layer thickness in a second substrate area in which the optically variable security element is arranged.
9. The method as claimed in claim 8, characterized in that the ink-receiving layer is applied by gravure printing using a printing form which has a first and a second printing area which, during the gravure printing, in each case come to lie on the first and second substrate area, wherein the second printing area has a reduced printing ink receiving capacity compared with the first printing area.
10. The method as claimed in claim 9, characterized in that the printing form has cells which, in the second printing area, have a reduced size, a reduced spacing and/or a reduced depth as compared with the first printing area.
11. The method as claimed in claim 9 or 10, characterized in that the printing ink receiving capacity within the second printing area, starting from the printing ink receiving capacity in the first printing area, has a course that decreases in the form of a staircase or continuously, preferably with a constant gradient.
12. The method as claimed in claim 11, characterized in that the application of the ink-receiving layer is carried out by a plurality of printing forms in a plurality of partial steps, wherein the plurality of printing forms in the respective second printing areas have a staircase-like course of the printing ink receiving capacity that is respectively offset relative to the remaining printing forms.
13. An apparatus for implementing a method as claimed in one of claims 8 to 12, which preferably has a multiplicity of press cylinders for applying an ink-receiving layer, wherein the multiplicity of press cylinders have a staircase-like course of a printing ink receiving capacity that is respectively offset relative to the remaining press cylinders.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102009020846.1 | 2009-05-12 | ||
| DE200910020846 DE102009020846A1 (en) | 2009-05-12 | 2009-05-12 | Ink receiving layer with recess |
| PCT/EP2010/056496 WO2010130755A2 (en) | 2009-05-12 | 2010-05-11 | Ink-receiving layer having a recess |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2761755A1 true CA2761755A1 (en) | 2010-11-18 |
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| CA2761755A Expired - Fee Related CA2761755C (en) | 2009-05-12 | 2010-05-11 | Ink-receiving layer having a recess |
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| CN (1) | CN102459759B (en) |
| AU (1) | AU2010247373C1 (en) |
| BR (1) | BRPI1014303A2 (en) |
| CA (1) | CA2761755C (en) |
| DE (1) | DE102009020846A1 (en) |
| ES (1) | ES2619841T3 (en) |
| MX (1) | MX2011011936A (en) |
| RU (1) | RU2572126C2 (en) |
| WO (1) | WO2010130755A2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114127362A (en) * | 2019-08-07 | 2022-03-01 | 捷德货币技术有限责任公司 | Method for producing security paper and security paper obtainable thereby |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102179966A (en) * | 2011-01-20 | 2011-09-14 | 中国人民银行印制科学技术研究所 | Anti-counterfeiting element and anti-counterfeiting product |
| GB2542786B (en) * | 2015-09-29 | 2018-02-28 | De La Rue Int Ltd | Security print media and method of manufacture thereof |
| GB2542783B (en) * | 2015-09-29 | 2018-02-07 | De La Rue Int Ltd | Security print media and method of manufacture thereof |
| MA43351A (en) * | 2015-09-29 | 2018-08-08 | De La Rue Int Ltd | SAFETY PRINTING DEVICE AND ITS MANUFACTURING PROCESS |
| GB2542784B (en) * | 2015-09-29 | 2018-08-01 | De La Rue Int Ltd | Security print media and method of manufacture thereof |
| DE102016015546A1 (en) * | 2016-12-27 | 2018-06-28 | Giesecke+Devrient Currency Technology Gmbh | Multilayer value document substrate |
| DE102017003795A1 (en) | 2017-04-19 | 2018-10-25 | Giesecke+Devrient Currency Technology Gmbh | Polymeric value document substrate, security element, value document and manufacturing method |
| AU2018271143B2 (en) | 2017-05-17 | 2023-05-11 | Ccl Secure Pty Ltd | A banknote and a method of producing a banknote |
| DE102019007696A1 (en) | 2019-11-06 | 2021-05-06 | Giesecke+Devrient Currency Technology Gmbh | Value document |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| EP0343104A3 (en) * | 1988-05-18 | 1990-08-08 | De La Rue Giori S.A. | Perfecting web-fed press, particularly for bank notes |
| DE4002979A1 (en) * | 1990-02-01 | 1991-08-08 | Gao Ges Automation Org | Banknote with optically variable security elements - are transformed and pressed onto smooth surface to form hologram or relief pattern |
| ITMI920068A1 (en) * | 1992-01-16 | 1993-07-16 | Francesco Bosisio | PROCEDURE FOR THE PROTECTION OF WRITINGS ON PAPER DOCUMENTS IN SPECIFIC BANK CHECKS |
| FR2687417A1 (en) * | 1992-02-13 | 1993-08-20 | Arjo Wiggins Sa | PRINTABLE SHEET INFALSIFIABLE BY MECHANICAL METHODS. |
| FR2814476B1 (en) * | 2000-09-11 | 2003-04-11 | Arjo Wiggins Sa | SAFETY SHEET HAVING A TRANSPARENT OR TRANSLUCENT LAYER |
| DE10124630A1 (en) * | 2001-05-18 | 2002-11-21 | Giesecke & Devrient Gmbh | Security, especially banknote, with printed symbols and security element, is coated with mat protective varnish except over security element |
| RU2322695C2 (en) * | 2001-12-21 | 2008-04-20 | Гизеке Унд Девриент Гмбх | Sheet material, and also devices and methods for manufacturing and processing such sheet material |
| DE102009007779C5 (en) * | 2009-02-04 | 2017-07-27 | Bundesdruckerei Gmbh | A method for producing a visually perceptible without technical aids security feature, security feature for plastic-based value or security document and document with at least one such security feature |
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- 2009-05-12 DE DE200910020846 patent/DE102009020846A1/en not_active Withdrawn
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- 2010-05-11 ES ES10718994.6T patent/ES2619841T3/en active Active
- 2010-05-11 WO PCT/EP2010/056496 patent/WO2010130755A2/en active Application Filing
- 2010-05-11 CA CA2761755A patent/CA2761755C/en not_active Expired - Fee Related
- 2010-05-11 BR BRPI1014303A patent/BRPI1014303A2/en not_active Application Discontinuation
- 2010-05-11 MX MX2011011936A patent/MX2011011936A/en active IP Right Grant
- 2010-05-11 RU RU2011150113/05A patent/RU2572126C2/en not_active IP Right Cessation
- 2010-05-11 AU AU2010247373A patent/AU2010247373C1/en not_active Withdrawn - After Issue
- 2010-05-11 CN CN201080031391.3A patent/CN102459759B/en active Active
- 2010-05-11 EP EP10718994.6A patent/EP2430237B1/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114127362A (en) * | 2019-08-07 | 2022-03-01 | 捷德货币技术有限责任公司 | Method for producing security paper and security paper obtainable thereby |
| CN114127362B (en) * | 2019-08-07 | 2023-08-04 | 捷德货币技术有限责任公司 | Method for producing security papers and security papers obtainable thereby |
Also Published As
| Publication number | Publication date |
|---|---|
| ES2619841T3 (en) | 2017-06-27 |
| DE102009020846A1 (en) | 2010-11-25 |
| AU2010247373C1 (en) | 2014-10-23 |
| RU2011150113A (en) | 2014-06-20 |
| RU2572126C2 (en) | 2015-12-27 |
| AU2010247373A1 (en) | 2011-12-01 |
| MX2011011936A (en) | 2011-12-06 |
| CA2761755C (en) | 2014-03-04 |
| CN102459759A (en) | 2012-05-16 |
| CN102459759B (en) | 2014-08-20 |
| EP2430237A2 (en) | 2012-03-21 |
| WO2010130755A2 (en) | 2010-11-18 |
| AU2010247373B2 (en) | 2013-07-11 |
| WO2010130755A3 (en) | 2011-01-06 |
| EP2430237B1 (en) | 2017-01-25 |
| BRPI1014303A2 (en) | 2016-04-05 |
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| EEER | Examination request | ||
| MKLA | Lapsed |
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| MKLA | Lapsed |
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