EP1318016B1 - Method for superposing several layers printed in register - Google Patents

Description

The invention relates to a method for the production of registered printed multilayer structures in various printing units.

In the production of multiple functional layers by means of different printing processes, it may be necessary to interrupt the printing process and then introduce the already printed web in another printing unit to apply more layers on the already printed web. However, these additional layers must be applied register-accurate in the longitudinal and side register.

In the EP-A 504 486 a method for register accurate, multi-color printing of a web is described, in which the web is passed through a plurality of printing units, each printing cylinder imprinted a partial print image in a particular ink, on the web markings (marks and lines) are mitaufgedruckt to the Detecting the relative pressure position of the printing cylinder to the web transversely to the transport direction are scanned optically by sensors, in which case the respective pressure cylinder is displaced accordingly.
If the printing process has to be interrupted, the procedure is not sufficient. Since the complexity of the process steps due to the ever-increasing required precision and properties of the webs, especially in security elements, increasing more often, a printing process is often no longer sufficient on presses with 10 commissioned works.

The object of the invention was therefore to provide a method in which it is possible to apply to a provided unprinted substrate printing layers with the highest precision and then to these layers in a separate operation both in the longitudinal and in the transverse direction register within the smallest tolerances to apply further layers.

The invention therefore provides a method according to claim 1.

The already printed web has registration marks and control lines which are measured inline to determine the exact registration distances by means of optical sensors.

If the distance between the register marks is greater than the required register length, shrinking by means of a dryer, for example by heating by means of an IR dryer, a heating roller or a convection dryer preshrunk the printed material web to the required length, the distance between the register marks is less than the required register length, the printed web is suitably between two draw groups or several times in succession with several pull groups pre-stretched to the appropriate length.

Before the first printing unit, the material web thus adjusted to the corresponding length is subsequently fed in via a register roller. In the side register, the correct control takes place via a path control or via a swivel frame, as well as via a displaceable cylinder. Subsequently, the printing process is carried out with longitudinal and side register control.

By this method, it is possible to apply several layers register accurate, both in the longitudinal and in the side register and both on the front and on the back optionally using a turning station within the smallest tolerances. Furthermore, when using an additional laminating two or more printed films can be laminated register accurate.

As a material web are, for example, carrier films, preferably flexible plastic films, for example, from Pl, PP, MOPP, PE, PPS, PEEK, PEK, PEI, PSU, PAEK, LCP, PEN, PBT, PET, PA, PC, COC, POM, ABS, PVC in question. The carrier films preferably have a thickness of 5 to 700 .mu.m, preferably 8 to 200 .mu.m, more preferably 12 to 50 .mu.m.

Furthermore, metal foils, for example Al, Cu, Sn, Ni, Fe or stainless steel foils having a thickness of 5-200 μm, preferably 10 to 80 μm, particularly preferably 20-50 μm, may also serve as the carrier substrate. The films can also be surface-treated, coated or laminated, for example with plastics, or painted.
Further, as carrier substrates also paper or composites with paper, for example, composites with plastics with a grammage 20-500 g / m ^2, preferably 40-200 g / m ^2. be used.

Further, as carrier substrates, woven or nonwoven fabrics, such as continuous fiber fabrics or nonwovens, staple fiber fabrics or nonwovens, and the like, which may optionally be needled or calendered, may be used. Preferably, such fabrics or webs of plastics, such as PP, PET, PA, PPS and the like, but it can also be woven or nonwovens of natural, optionally treated fibers, such as viscose fiber fabric or nonwoven fabrics used. The fabrics or nonwovens used have a basis weight of about 20 g / m ² to 500 g / m ² .

The layer already present on the carrier substrate may be a paint or lacquer layer, a surface-structured layer, a metal layer, a partially (positively or negatively) metallized layer, a conductive layer, a magnetic layer and the like. These layers can be applied both over the entire surface as well as partially.

The application of the layer may be effected by any method such as gravure, flexo, screen, offset, digital (inkjet, dry and liquid), and the like, with register marks for the longitudinal register and control lines for the register to determine register length Page registers were taken.

These register marks are then measured inline by means of optical sensors and the material web already provided with one or more layers is introduced via a registration roller into the first printing unit and printed with one or more further layers.

The further layer may in turn be a paint or lacquer layer, a surface-structured layer, a metal layer, a conductive layer, a magnetic layer and the like. These layers can in turn be applied both over the entire surface as well as partially.

The printed layer (s) already present on the material web or the layers applied in the further separate steps may correspond or be different and will be described below.

As color or lacquer layers in each case a wide variety of compositions can be used. The composition of the individual layers may in particular vary according to their purpose, that is to say whether the individual layers serve exclusively for decorative purposes or should represent a functional layer or whether the layer should be both a decoration layer and a functional layer.

The layers to be printed may be pigmented or unpigmented. As the pigments, there may be used any known pigments, for example, inorganic-based pigments such as titanium dioxide, zinc sulfide, kaolin, ITO, ATO, FTO, aluminum, chromium and silicon oxides, or organic-based pigments such as phthalocyanine blue, i-indolidine yellow, dioxazine violet and the like It is also possible to use colored and / or encapsulated pigments in chemically, physically or reactively drying binder systems. Examples of suitable dyes are 1,1- or 1,2-chromium-cobalt complexes.
Solvent-containing paint and / or paint systems, aqueous and solvent-free paint systems can be used.
Suitable binders are various natural or synthetic binders.

For example, the functional layers may have certain electrical, magnetic, chemical, physical and also optical properties.

For adjusting electrical properties, for example conductivity, graphite, carbon black, conductive organic or inorganic polymers, metal pigments (for example copper, aluminum, silver, gold, Iron, chromium and the like), metal alloys such as copper-zinc or copper-aluminum or amorphous or crystalline ceramic pigments such as ITO, FTO, ATO and the like may be added. Furthermore, doped or non-doped semiconductors such as, for example, silicon, germanium, gallium arsenide, arsenic or ion conductors such as amorphous or crystalline metal oxides or metal sulfides can also be used as an additive. Furthermore, polar or partially polar compounds such as surfactants or nonpolar compounds such as silicone additives or hygroscopic or non-hygroscopic salts can be used or added to adjust the electrical properties of the layer. Likewise, intrinsically conductive organic polymers such as polyaniline, polyacetylene, Polyethylendioxythiophen and / or polystyrene sulfonate can be added.

To adjust the magnetic properties, paramagnetic, diamagnetic and also ferromagnetic substances, such as iron, nickel, barium, and cobalt or their compounds or salts (for example, oxides or sulfides) can be used. Particularly suitable are Fe (II) and Fe (III) oxides, barium or cobalt ferrites, rare earths and the like.

The optical properties of the layer can be visualized by visible colors or pigments, luminescent dyes or pigments which fluoresce or phosphoresce in the visible, in the UV region or in the IR range, heat-sensitive inks or pigments, effect pigments, such as liquid crystals, pearlescent pigments. , Bronze and / or multilayer color change pigments influence. These can be used in all possible combinations.

Various properties can also be combined by adding various additives mentioned above. Thus, it is possible to use colored and / or conductive magnetic pigments. All mentioned conductive additives can be used.
Especially for the dyeing of magnetic pigments it is possible to use all known soluble and non-soluble dyes or pigments. So can For example, a brown magnetic paint by the addition of metals in their color metallic, for example, be set silvery.

For printing soluble layers, the paint or varnish used may be soluble in a solvent, preferably water, but a dye soluble in any solvent, for example in alcohol, esters and the like may also be used. The paint or lacquer may be conventional compositions based on natural or artificial macromolecules. The color may be pigmented or unpigmented. As pigments, all known pigments can be used. Particularly suitable are TiO ₂ , ZnS, kaolin and the like.
If a soluble (partial) color layer is used, it may optionally be removed after application of another layer in the process according to the invention by a suitable solvent adapted to the composition of the color layer in order to produce codes in the form of characters and / or patterns of any possible kind to be able to, for example in DE 101 43 523 described.

But it can also be applied intermediate layers of a metal, a metal compound, an alloy or an insulator. As the metal layer, layers of Al, Cu, Fe, Ag, Au, Cr, Ni, Zn and the like are suitable. Examples of suitable metal compounds are oxides or sulfides of metals, in particular TiO ₂ , Cr oxides, ZnS, ITO, ATO, FTO, ZnO, Al ₂ O ₃ or silicon oxides. Suitable alloys are, for example, Cu-Al alloys, Cu-Zn alloys and the like. As insulators, for example, organic substances and their derivatives and compounds, such as paint and lacquer systems, such as epoxy, polyester, rosin, acrylate, alkyd, melamine, PVA, PVC, isocyanate, urethane, the radiation-curing can be, for example, by heat or UV or electron radiation suitable.

All dyes and pigments may be used singly or in combination with various natural or synthetic binders, e.g. natural oils and resins such as phenol-formaldehyde, urea, melamine, ketone, aldehyde, epoxy, polyterpene resins. As additional binders, for example, polyesters, polyvinyl alcohols, polyvinyl acetates, ethers, propionates and chlorides, poly (methyl) acrylates, polystyrenes, olefins, nitrocellulose, polyisocyanate, urethane systems and others can be used.

All of these layers can be applied by known methods such as sputtering, sputtering, printing (gravure, flexo, screen, digital offset, and the like), spraying, electroplating, and the like.

Before application of these layers, the web can be treated by means of an in-line plasma (low pressure or atmospheric plasma), corona or flame process. The surface is activated, producing terminal polar groups on the surface and cleaning the surface. This improves the adhesion of metals, paints and varnishes to the surface.

Optionally, simultaneously with or after the application of the plasma or corona or flame treatment, a thin metal or metal oxide layer can be applied as adhesion promoter, for example by sputtering or vapor deposition. Particularly suitable are Cr, Al, Ag, Ti, Cu, TiO ₂ , Si oxides or chromium oxides. This adhesion promoter layer generally has a thickness of 0.1 nm-5 nm, preferably 0.2 nm-2 nm, particularly preferably 0.2 to 1.0 nm

As a result, the adhesion of the partially or completely applied optionally structured functional layer is further improved. This is a prerequisite for the production of functional layers with high precision and good adhesion.

However, it is also possible for a layer which has or has a surface structure, for example a diffraction structure or a surface relief, to be applied, wherein this structure is preferably embossed into a radiation-curable lacquer layer.
Furthermore, further layers can be applied by known methods, for example direct metallization methods, partial metallization methods register-accurate, over the entire area or partially.

These layers may each have encodings or negative encodings in the form of patterns, characters, micro and macro lines, letters, images, mathematically definable line elements, reliefs, guilloches, as well as machine-readable elements and the like.

The superimposed layers may have different properties. By combining different properties of the individual layers, for example layers having different conductivity, magnetizability, optical properties, absorption behavior and the like, it is possible to produce, for example, security elements having a plurality of precise authenticity features.

Optionally, the coated material web thus produced can also be protected by a protective lacquer layer or further refined, for example, by laminating or the like.

Due to the high precision of the dimensions of the applied layers, the material webs produced according to the invention are, in particular, optionally after cutting into strips or bands, for example with a width of 0.2 to 75 mm, as security elements, in particular in value documents and data carriers, for example banknotes, securities, identification documents , Cards and the like used or as security elements or security labels in packaging, textiles, seals and the like and used as tear threads.

Due to the excellent precision and the possibility of producing multilayer, very thin films by the process according to the invention, the products according to the invention are also particularly suitable for embedding in banknotes and the like. For this purpose, the printed material web is initially cut register exactly according to the applied layers in strips, strips or other formats and then embedded or applied.

Optionally, the product can be applied with a sealable adhesive, such as a hot or cold seal adhesive or a pressure-sensitive adhesive to the corresponding substrate, or embedded in paper for security papers by conventional methods, for example. If appropriate, the seal adhesives can likewise be applied in the described method according to the invention.

These sealants can be equipped with visible or visible in the UV light, fluorescent, phosphorescent or laser and IR radiation absorbing and reflecting features to increase the security against counterfeiting. These features can also be present in the form of patterns or characters or show color effects, any number of colors or color mixtures, preferably 1 to 12 colors or color mixtures printed in register are possible.

The carrier substrate may be removed after application or remain on the product in one-sided coating. In this case, the carrier film may optionally be specially equipped on the uncoated side, for example, scratch-resistant, antistatic and the like. The same applies to a possible lacquer layer on the carrier substrate.

In Fig. 1 the process of the invention is shown.

1, the material web coming from the mother roll, 2 the length measuring device (sensors), 3 a dryer, 4 the first drawing group, 4a the second drawing group, 5 the register scanning and length control, 6 the register roll before the first printing unit and 7 the printing unit.

The provided by the parent roll with register marks and control lines and already arbitrarily printed material web is guided over a guide roller by the length measuring device, which preferably consists of 2 sensors.

Depending on the result of the length measurement, i. the evaluation of the distance between two or more register marks, then the web is set either by shrinkage by means of a dryer or by stretching between two or more train groups to the corresponding register length.

The control of the distance between the register marks is carried out via a control loop, in particular a register controller, which scans the distance between the register marks and controls and triggers a corresponding control of the two train groups.

Subsequently, the set with a control loop, such as a register controller, set to the correct register length material web is controlled via a register roller in the printing unit.
The correct control of the side register is carried out simultaneously via a web control and / or a swing frame, the fine control is effected by lateral displacement of the printing cylinder.

In the printing unit, the already printed material web thus printed is subsequently printed in registration and registration.

In this way, one or more times printed material webs in different printing units each optionally with interruption of the operation can be easily and inexpensively printed register and register exactly on the front and back as often as desired with different or similar layers. Furthermore, if another laminating unit is used, two or more printed film webs can also be laminated inline in register.

Particularly good results are achieved when using a carrier substrate, such as a film, a paper and the like with limited and reproducible shrinkage-expansion behavior.

An example of a product produced by the process according to the invention is in Fig. 2 represented here, where two previously separated with different layers register printed material webs were then laminated register accurate.

1 is a heat-sealable adhesive, 2 is a PET film, 3 is a primer, 4 is a surface-structured layer, 5 is a partial metallic layer, for example an Al layer, 6 is a magnetic layer, 7 is an adhesive layer and 8 a to 8 d is a fluorescent color layer with a color gradient ,

Claims (7)

1. Method for producing multilayer structures which are printed in register, also in a plurality of print operations which are independent of one another on a material web which has already been coated or printed with register marks and control lines, measuring being carried out between two or more register marks according to the length via a measuring device (2) which is positioned in front, and the necessary register length being set between two or more actuated pulling groups (4, 4a), the correct register length being determined by inline measurement of the register marks and the correct register length being carried out by shrinking by means of a dryer or stretching between the two or more pulling groups, and the material web which has already been provided with a defined printed layer with register marks and control lines being controlled in register subsequently by a regulating circuit, in particular a register regulator, via a register roll in front of the first printing unit, the lateral register being pilot-controlled via a web controller and/or being controlled via a pivoting frame, whereupon the material web is printed with one or more functional or decorative layers in registration and register with respect to the coating which is already present on the material web.
2. Method according to Claim 1, a plurality of functional ink layers and/or metallic layers and/or surface-structured layers and/or conductive and/or magnetic layers and/or optical layers being printed in sequence in one work operation or in different printing units.
3. Method according to either of Claims 1 and 2, the specified method steps being repeated once or multiple times to apply different layers.
4. Method according to one of Claims 1 to 3, the layers being printed in registration on the front side and on the rear side, optionally with the use of a turning station.
5. Method according to one of Claims 1 to 4, two or more printed material webs being laminated in register using a laminating unit.
6. Method according to one of Claims 1 to 5, the produced material webs subsequently being cut in register into tapes, strips or other formats.
7. Use of the method according to one of Claims 1 to 6 for producing security elements, in particular in documents of value and data carriers, for example banknotes, papers of value, identity documents, maps or security elements or security labels in packagings, textiles, seals and as tear-open thread.

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