EP1741005A1

EP1741005A1 - Method for relief-printing highly conductive paths onto conducting substrates

Info

Publication number: EP1741005A1
Application number: EP05744141A
Authority: EP
Inventors: Peter Reich; Hans Hermann Kammerer
Original assignee: Hueck Folien GmbH and Co KG
Current assignee: Constantia Pirk and Co KG GmbH
Priority date: 2004-04-29
Filing date: 2005-04-25
Publication date: 2007-01-10
Also published as: WO2005106586A1

Abstract

Disclosed is a method for printing highly conductive paths or structures onto preferably conductive substrates. Substrates produced according to said method are particularly suitable for packages in which removal of the packaged object is to be detected and verified, e.g. in packages for medicaments, medical instruments, or medical aid material.

Description

Process for printing highly conductive webs in gravure printing on conductive substrates

The invention relates to a method for printing highly conductive webs on conductive substrates.

In the case of a large number of packs of the most varied objects, it is necessary or desirable that the time at which the pack is opened or tampered with can be determined. This is important, for example, when taking medication, medical instruments or aids and the like.

In particular, when taking medication regularly, it is desirable that the dispensing of the medication is checked primarily over time. Various options for checking the removal of a medicament from its packaging are already known, for example from DE-A 197 13 915, DE-A 100 60 375 or US 2003/0007421.

The control of the withdrawal time of a medicament is currently most advantageously solved by the fact that conductor tracks are applied to the packaging at the appropriate points, which provide contact information (for example pressing through or opening the packaging) to a small computer either located directly on the packaging or an external small computer or pass on a logic circuit.

Packaging of medicaments of all dosage forms, such as tablets, film-coated tablets, dragees, suppositories, infusion bags, syrups, gels, pastes and the like, are mostly produced from foils, for example electrically conductive plastic foils, metallized plastic foils, soft or hard aluminum foils or composites with aluminum foils or plastic foils, in particular the sealing layers are mostly made of such Materials made. Since these foils or composites themselves are already conductive, the conductive path or structure (circuits) applied to them must on the one hand have appropriate insulation to the conductive substrate and on the other hand have a defined resistance in order to enable appropriate transmission of the contact information to the small computer or a logic circuit ,

The object of the invention was to provide a method and an apparatus for printing highly conductive webs and structures on conductive substrates, the printed layers having both sufficient insulation from the conductive substrate and sufficient conductivity to transmit information to a small computer or a logic circuit exhibit.

The invention therefore relates to a method for printing highly conductive layers on conductive substrates, characterized in that for the printing of the highly conductive layers an intaglio cylinder is used which has been exposed to an excessive G ratio and as printing inks electrically conductive printing inks with conductive pigments whose size is matched to the structure of the impression cylinder can be used.

The geometry of the halftone dot shape is influenced by setting an increased G ratio. In particular, well volume, grid point area and web width are influenced and adapted. An increased G ratio is understood here to mean a G ratio greater than 65%.

The gravure cylinder used is exposed with an increased G-ratio. This exaggerated G ratio creates a very thin bridge, which increases the size of the cells in the surface. (Such a surface is shown in FIG. 1, where 1 denotes the cells and 2 the webs.) As a result, the cells can be filled completely with the appropriate printing ink even with larger pigments. Further the reproduction of the cell on the substrate is better due to the enlarged contact surface, since the adhesive forces of the cylinder are opposed to a larger contact surface. The thin webs between the cells are flooded by the printing ink during the printing process (printing ink exchange between the individual cells of the cylinder). This ensures the corresponding conductance or resistance.

The coordination of the pigment size to the structure of the printing cylinder is within the range of the usual tasks of the person skilled in the art.

If the pigment size is appropriate, the printing ink flows between the cells in a defined manner. The print surface thus created results in a closed or homogeneous surface on the substrate, which has an insulating function to the conductive substrate. In a further step, the conductor track surface, which acts as a closed conductor, is then applied.

As a result, the resistances of <50 ohms, preferably 29-32 ohms, required for the specific application described above are achieved per defined switching segment.

To produce the corresponding gravure cylinder, for example, a laser or electron beam is used to place one on the cylinder, for example a gravure cylinder with a core made of iron tube with a wall thickness of 20 mm, and the following layers: 5-7 μm nickel layer,

300μm copper layer; existing photosensitive layer with the corresponding patterns, shapes, lines, letters, which are connected to each other, illustrated, developed and etched in the form of the previously defined grid with excessive G-Ratio.

The cylinder is coated in the usual way with a plastic transfer wheel, or by spraying, rolling, brushing, dipping, or by means of a curtain application process, preferably in one Layer thickness of 2 - 10 μm with a commercially available photosensitive composition, for example LD 100, OHKA Kogyo Ltd.

However, all other known and commercially available compositions are also suitable. The cylinder is then covered with an overcoat with a layer thickness of 1-5 μm, for example with OC-40 (from OHKA Kogyo Ltd) or with an analogous, similar, commercially available composition.

Development takes place after exposure in the usual way, for example without contact with sodium carbonate (0.5% solution), followed by a cleaning process with water and the cylinder is dried.

The image, pattern, shapes and the like defined by the laser or electron beam imaging are reflected on the surface of the cylinder by a subsequent conventional etching process following the laser or electron beam imaging. The etching can be carried out in various ways, for example by means of an Fe (III) chloride solution or a Cu (II) chloride solution, optionally with the addition of HCl or H ₂ SO ₄ . If necessary, commercially available and known additives for flank protection can also be added to the etching solution.

The duration of the action of the etchant depends on the etchant used and is, for example when using a Cu chloride solution with the addition of an acid, about 90-2400 sec.

However, an electrochemical etching process can also be used.

After the etching process, the cylinder appears dull and optically dark. A surface treatment with the electrolytic or chemical shine enhances the impression structure and creates a brilliant surface. However, this post-treatment of the cylinder is not absolutely necessary for the application according to the invention, but it does improve the impression result. Anodizing or polishing is a valuable addition to the various polishing processes, but it is not a universal replacement for other processes. Neither all metals are suitable for this, nor can all desired surface profiles be produced with this process. These restrictive findings are important because failures and disappointments can only be avoided by marking out the limits of the application. The essence of anodic polishing, also electrolytic polishing or electropolishing, is that the surface to be polished as a positive pole, anode, in a suitable solution, the electrolyte, which has to be specially matched to the metal to be treated, more or less long, usually a few minutes to a quarter of an hour. The electropolishing process is therefore reversed like the galvanic metal deposition on the cathode. The anodically switched metal dissolves in the electrolyte, but the dissolution takes place more strongly at the micro elevations on the surface than in the depressions. This results in a gradual leveling and smoothing in the micro range, which can lead to a high gloss.

The prerequisite for the success of electropolishing is that there is a polishable metal and that the appropriate electrolyte is used. Most homogeneous metals and alloys can be polished well. For example, the process is particularly suitable for stainless chrome-nickel steels, for many hard metals, for pure aluminum and not too high-alloyed aluminum, for copper-rich brass and other copper alloys, for precious metals. Various of the metals mentioned are difficult to bring mechanically to a high gloss. In heterogeneous, multi-phase systems, such as carbon steels, zinc-rich or lead-containing brass, cast aluminum alloys, the individual phases are attacked to different degrees, so that it is usually not possible to achieve perfect high gloss with these metals by anodic polishing. However, achieving a silky sheen is often possible. The preferred attack on the areas protruding from the surface means that burrs on the workpiece are removed quickly. Electropolishing is therefore ideal for deburring workpieces, especially those that are difficult to deburr in other ways or that would require a lot of manual work. As a rule, the composition of the base metal, single-phase or multi-phase, is irrelevant for deburring, and metals and alloys that are difficult to polish per se can also be well deburred electrolytically.

In contrast to mechanical processes, anodic polishing has no mechanical effect on the surface of the workpiece; rather, superficial layers, which were deformed by a previous mechanical treatment and which received internal stresses, are removed during electropolishing, so that the unchanged basic structure of the material appears superficially.

This peculiarity of anodic polishing also means that existing surface defects, such as cavities, grooves, cracks, inclusions, are not smeared as is the case with mechanical polishing, but that these defects are more likely to appear after anodic treatment. However, this is often a very valuable feature of these processes. The flaws that are smeared during mechanical polishing or otherwise hidden only fake a flawless surface that is not actually present, but which very often reveals these defects clearly during subsequent treatment, for example in galvanic baths. The anodic polishing allows rejects to be recognized as such before further work has been done on them. For this reason, the method is often used for troubleshooting. (An example of many is the testing of turbine blades for aircraft engines for correctness.) During the anodic polishing process, metal is preferably dissolved at the points protruding from the surface. This leads to progressive smoothing and leveling. Macro roughness or unevenness remain unaffected. It is therefore not possible to produce an ideally flat surface or any other specific geometric profile by anodic polishing. If such a surface is required, the macro profile is to be produced by prior mechanical treatment, including mechanical grinding and polishing, and only then is the elimination of the micro-roughness still present and the production of high gloss by electrolysis.

Accordingly, if a slightly wavy, matt surface is electropolished, the waviness is essentially retained, even if a high gloss is achieved. If the same initial surface is mechanically ground or polished, the waviness is eliminated, but the resulting surface always shows the grinding or polishing marks according to the size of the abrasive grain used if the magnification is sufficiently strong.

Anodically polished surfaces are characterized primarily by the lack of micro-roughness. This results in various valuable properties of these surfaces that are used technically: high gloss and best reflectivity (optics, decorative use), low friction coefficient, therefore lower friction losses and reduced frictional heat and less frictional wear (gears, bearings, shafts, pistons, piston rings, etc.) ), lower adsorption capacity and absorption capacity for gases and liquids (vacuum technology), it is also important wherever particular importance is attached to great purity and cleaning options (medical devices,

Hospital facilities, dyeing tubs, pressure rollers).

Compared to mechanical processes, electropolishing has some very valuable advantages: it does not require expensive skilled manual work Forces, all sources of accidents and dangers that often exist during mechanical polishing are eliminated, even complicated shapes and metals that are difficult to polish can be easily electropolished, there is no dust nuisance.

The disadvantages to be mentioned are the non-universal applicability, the handling with often very concentrated acids, or generally the wet processing in companies that otherwise do not use wet treatment, relatively expensive systems, the accumulation of waste water that has to be specially treated, for what own Attachments are needed.

The processes can be fully automated, and the production of small parts in large quantities in specially developed devices is also possible.

The chemical shine differs from the electrolytic processes in that no external power source is required. However, the surface is removed in the same way as for anodic polishing. Instead of the direct effect of the electric current, correspondingly aggressive chemicals are used, which naturally consume the controlled degradation of the surface, that is to say continuously, and must be constantly supplemented. These solutions must also be specially tailored to each metal to be treated, which is more critical here than with the anodic polishing processes. Since there are no external power sources, the system costs are considerably lower than for electrolytic processes. On the other hand, the ongoing chemical costs, which replace the electricity costs, are usually higher.

The nature of the chemically polished surfaces is basically the same as that of anodised surfaces. With regard to the consumption of chemicals, the processes are mainly used where only small amounts of material can be removed. Because of the extremely simple handling and the cheap facilities, however, they are large technically applied. The oldest process in this series is the bright burn of brass and other copper alloys. Recently, light alloys in particular have been shined in this way.

Depending on the ink with conductive pigments, a grid of the appropriate size is selected.

Suitable electrically conductive pigments are preferred, for example

Pigments based on silver, nickel or graphite.

Paints or varnishes with metal pigments (e.g. copper, aluminum,

Silver, gold, iron, chromium and the like), metal alloys such as copper-zinc or copper-aluminum are also possible.

Furthermore, doped or non-doped semiconductors such as, for example

Silicon, germanium or ionic conductors such as amorphous or crystalline metal oxides or metal sulfides can be used as additives. Furthermore, polar or partially polar can be used to adjust the electrical properties of the layer

Compounds such as surfactants or non-polar compounds such as silicone additives or hygroscopic or non-hygroscopic salts are used or added.

The pigments can be used both in solvent-free and in solvent-containing systems, if appropriate with a binder as a paint or varnish.

Examples of suitable solvents are water or organic solvents, such as alcohols, ketones, aldehydes, aliphates or aromatics and the like.

Various natural or synthetic binders come into question as binders, for example using natural oils and resins such as phenol formaldehyde, urea, melamine, ketone, aldehyde, epoxy and polyterpene resins. Additional binders that can be used include, for example, polyesters, polyvinyl alcohols, polyvinyl acetates, ethers, propionates and chlorides, poly (methyl) acrylates, Polystyrenes, olefins, nitrocellulose, polyisocyanate, urethane systems and the like.

Conductive but also non-conductive carrier substrates can be used as carrier substrates.

Carrier substrates include, for example, carrier films, preferably flexible transparent plastic films, for example made of PI, PP, MOPP, PE, PPS, PEEK, PEK, PEI, PAEK, LCP, PEN, PBT, PET, PA, PC, COC, POM, ABS, PVC in question.

The carrier films preferably have a thickness of 5 to 700 μm, preferably 5 to 200 μm, particularly preferably 5 to 50 μm.

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.

Furthermore, woven or nonwovens, such as continuous fiber nonwovens, staple fiber nonwovens and the like, which can optionally be needled and / or calendered, can be used as carrier substrates. Such fabrics or nonwovens preferably consist of plastics, such as PP, PET, PA, PPS and the like, but fabrics or nonwovens made of natural, optionally treated fibers, such as viscose fibers, can also be used. The nonwovens or fabrics used have a weight per unit area of approximately 20 g / m ² to 500 g / m ² . If necessary, the nonwovens or fabrics must be surface-treated.

In particular, conductive carrier substrates are suitable as carrier substrates, for example metal foils, for example Al, Cu, Sn, Ni, Fe or stainless steel foils with a thickness of 5-200 μm, preferably 10 to 80 μm, particularly preferably 20-50 μm serve. The slides can too surface-treated, coated or laminated, for example with

Plastics laminated or painted,

Al foils or aluminum foils are preferred for the desired application.

Plastic composites.

Furthermore, a full-surface or partial insulating layer can be applied. The conductor tracks and the contact areas for the external evaluation unit (small computer or logic circuit) are partially applied. The contact surfaces are also suitable for SMD elements (surface mounted device). In this way, complete circuits, for example integrated circuits, diodes, transistors, capacitors, can be applied directly to the carrier substrate, the SMD elements using a conductive adhesive, for example Loctite ® Chipbonder Set, can be fixed on the carrier substrate.

Furthermore, the carrier substrates can have further functional and / or decorative layers which have visually recognizable or machine-readable properties, for example optically recognizable features, optically active features such as diffraction structures or diffractive structures, or magnetic features and the like.

The carrier substrates printed in the manner described can be used to secure and control the removal times of objects, pharmaceuticals and the like from packaging.

Claims

claims:

1) Process for printing highly conductive layers on conductive substrates, characterized in that a gravure cylinder is used for printing the highly conductive layers, which has been exposed to an excessive G-Ratio and as printing inks electrically conductive printing inks with conductive pigments, the size of the structure of the impression cylinder is matched.

2) Method according to claim 1, characterized in that a dye or varnish exchange is possible between the wells of the gravure cylinder via thin webs.

3) Method according to one of claims 1 or 2, characterized in that pigments based on silver, nickel or graphite are used as electrically conductive pigments.

4) Method according to one of claims 1 or 2, characterized in that metal pigments such as copper, aluminum, silver, gold, iron, chromium and the like or pigments made of metal alloys are used as electrically conductive pigments.

5) Method according to one of claims 1 to 4, characterized in that the gravure cylinder has been electrochemically or chemically polished after exposure and development with an excessive G ratio.

6) substrates produced by a process according to claims 1 to 5.

7) Substrates according to claim 5, characterized in that the substrates have further functional and / or decorative layers. ) Use of the substrates according to one of claims 6 or 7 for securing and checking the removal times of objects, pharmaceuticals and the like from packaging.